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W;-"-.-'" 'I'a i'l'f'C'•• :.u."- -}s^:--.h.-' •', j Jl e •'.•i'..,'-i' - I - -.. • j ',1 I II 111 _ . , " 'i'l"l!ll"'i'll!ll-i'!-ll'!l;l ' ' ' ' iifyiiiiiiii I.: Vs. V U5593 ./JV. .*'"',;!: . • " • • • - Jl' "^ " • • ' • • ' . > i . , , 1 • • • ' - » - . ' 1 ' V I - • " 1, J 1 . 1 - * - • , . « . * • f • ' _ •• ^ ' - • - • • - . • " - • * . , - • . • i ' , V • , J . . I l l * * , . i • • f - " , J 11 \Mmi i n s i i I)^ RI PORI \ I R ' i l \ | s | \ \ | ) ( 111 \ii( \1 sill SI ( R()|\ I s \ | R ( , | \ M \\1)S r V - J i S C T t . jc- z:.i :.-;Zi-.-;L>.i.-._-i.">.c-' .... . - - f « ' , . / rf^^'Nv.' / ' • " • * * , * I • 1 . , V--- . - . . i ^•>-'.'", ) . ; . ^ I . J / f ,^ '^^ •• 400001 I Golder Associates Inc. 1951 Old Cuthbert Road, Suite 301 Cherry Hill, NJ 08034 Telephone (856) 616-8166 Fax (856) 616-1874 , Golder Associates FEASIBILITY STUDY REPORT . VIRGESl ISLAND CHEMICAL SITE ST. CROIX, U.S. VIRGIN ISLANDS P Prepared for: Berlex Laboratories, Inc. 15049 San Pablo Avenue P.O. Box 4099 Richmond, CA 94804 and Pharmacia & Upjohn 7171 Portage Road Kalamazoo, MI 49001 W DISTRIBUTION: 5 Copies 1 Copy ICopy 1 Copy 2 Copies June 2001 US Environmental Protection Agency Berlex Laboratories, Inc. Pharmacia & Upjohn Norma Eichlin Golder Associates Inc. Project No.: 003-6016 OFFICES ACROSS ASIA, AUSTRALASIA, EUROPE, NORTH AMERICA, SOUTH AMERICA 400002 • % p ^ June 2001 - i - 003-6016 TABLE OF CONTENTS Table of Contents i SECTION PAGE 1.0 INTRODUCTION 1 1.1 Overview 1 1.2 Site Description and History 2 2.0 CONCEPTUAL SITE MODEL 5 2.1 Site Geologic / Hydrogeologic Model. 5 2.2 Nature and Extent of Contamination 9 22.1 Soil Quality 9 2.2.2 Groundwater Quality 11 2.3 Natural Attenuation 13 2.3.1 General 13 2.3.2 Assessment of Natural Attenuation Processes 14 2.3.3 Trend Analysis 20 2.3.4 Fate and Transport Modeling 20 2.4 Summary of Site Risks 29 3.0 REMEDIAL ACTION OBJECTIVES 32 3.1 Preliminary Remediation Goals 32 3.1.1 ARARs and TBCs , 32 3.1.2 Preliminary Remediation Goals 34 4.0 DEVELOPMENT AND SCREENING OF ALTERNATIVES 35 4.1 General Response Actions 35 4.2 Screening of Technology and Process Options 35 4.3 Development of Alternatives 48 5.0 ALTERNATIVES RETAINED FOR DETAILED EVALUATION 50 5.1 Alternative 1: No Further Action 50 5.2 Alternative 2: Monitored Natural Attenuation (MNA) with Institutional Controls 50 5.3 Alternative 3: Source Control (SVE/AS) with Monitored Natural Attenuation 51 5.4 Alternative 4: SVE/AS with Groundwater Extraction and Treatment 53 5.5 Alternative 5: Groundwater Extraction and Treatment with MNA and Institutional Controls 55 6.0 NCP EVALUATION CRITERIA 56 7.0 DETAILED EVALUATION OF ALTERNATIVES 58 7.1 Alternative 1: No Action 58 7.2 Alternative 2: MNA with Institutional Controls 59 7.3 Alternative 3: Source Control (SVE/AS) with MNA 63 7.4 Alternative 4: SVE/AS With Groundwater Extraction and Treatment 66 7.5 Alternative 5: Groundwater Extraction and Treatment with MNA 69 7.6 Comparative Evaluation .' 72 8.0 REFERENCES :...76 Golder Associates 400003 % p ^ June 2001 - ii - 003-6016 TABLE OF CONTENTS (continued) LIST OF TABLES Table 1 Summary of Calculated Risks Table 2 Preliminary Remediation Goals Table 3 Estimated Drawdown, Pumping Rate, and Well Spacing in FPP Area Table 4 Estimated Drawdown, Pumping Rate, and Well Spacing in AST Area Table 5 Preliminary Cost Estimate - No Action Table 6 Preliminary Cost Estimate - Monitored Natural Attenuation Table 7 Preliminary Cost Estimate - Air Sparging/SVE/Natural Attenuation Table 8 Preliminary Cost Estimate - Groundwater Extraction/Treatment with SVE/AS Table 9 Preliminary Cost Estimate - Groundwater Extraction/Treatment with MNA LIST OF FIGURES Figure 1 Site Location Map Figure 2 Facility Layout Figure 3 Monitoring Well Location Map Figure 4 Composite Hydrogeologic Section A-A' Figure 5 Hydrographs for Shallow and Deep Wells in FPP Area Figure 6 Hydrographs for Shallow and Deep Wells in AST Area Figure 7 Shallow Groundwater Contour Map, 10/21/98 Figure 8 Deep Groundwater Contour Map, 10/21/98 Figure 9 Shallow Groundwater Contour Map 1/31/00 Figure 10 Shallow Groundwater Contour Map 3/6/00 Figure 11 Deep Groundwater Contour Map 3/6/00 Figure 12 Estimated Areal Extent of Impacted Soil - AST Area Figure 13 Estimated Areal Extent of Xylene Impacted Shallow Groundwater - AST Area Figure 14 Estimated Areal Extent of Ethylbenzene Impacted Shallow Groundwater - AST Area Figure 15 Estimated Areal Extent of Chloroform Impacted Shallow Groundwater - Process Pit Area Figure 16 Historic VOCs at FPP Area Figure 17 Historic VOCs at AST Area Figure 18 Model vs. Actual Xylene Concentrations Downgradient of Source Figure 19 Predicted Xylene Concentrations Downgradient of MW-6 Figure 20 Model vs. Actual Ethylbenzene Concentrations Downgradient of Source Figure 21 Predicted Ethylbenzene Concentrations Downgradient of MW-6 Figure 22 Model vs. Actual Chloroform Concentrations Downgradient of Source Figure 23 Predicted Chloroform Concentrations Downgradient of GWPP-27 Figure 24 Xylene Concentration Along Plume Centerline Figure 25 Total Xylenes Model Mass Balance Figure 26 Ethylbenzene Concentration Along Plume Centerline Figure 27 Ethylbenzene Model Mass Balance Figure 28 Chloroform Concentration Along Plume Centerline Figure 29 Chloroform Model Mass Balance Figure 30 Transient Bioscreen Analysis - Xylene: Input Data Figure 31 Transient Bioscreen Analysis - Xylene: 2000 Data Match Golder Associates 400004 I h June 2001 ni 003-6016 TABLE OF CONTENTS (continued) % LIST OF FIGURES Figure 32 Transient Bioscreen Analysis Figure 33 Transient Bioscreen Analysis Figure 34 Transient Bioscreen Analysis Figure 35 Transient Bioscreen Analysis Figure 36 Transient Bioscreen Analysis Figure 37 Transient Bioscreen Analysis Figure 38 Transient Bioscreen Analysis Simulation Figure 39 Chloroform Pulse Simulation: Figure 40 Chloroform Pulse Simulation: Figure 41 Chloroform Pulse Simulation: Figure 42 Conceptual Remediadon Plan: Figure 43 Conceptual Remediation Plan: Figure 44 Conceptual Remediation Plan SVE/AS Figure 45 Conceptual Remediation Plan - Xylene: Time to Compliance Simulation - Ethylbenzene: Data Input - Ethylbenzene: 2000 Data Match - Ethylbenzene: Time to Compliance Simulation - Chloroform (FPP Area): Data Input - Chloroform (FPP Area): 2000 Data Match - Chloroform (FPP Area): Time to Compliance Data Input 3-Year Travel Time 9-Year Travel Time with 40 ppb at MW-11 Monitored Natural Attenuation SVE/AS with MNA - Groundwater Extraction/Treatment with - Groundwater Extraction/Treatment with MNA P LIST OF APPENDICES Appendix A Detailed Cost Information Appendix B EPA Presumptive Remedy Guidance Golder Associates 400005 I p w June 2001 - 1 - 003-6016 LO INTRODUCTION 1.1 Overview This Feasibility Study (FS) Report for the Virgin Island Chemical (VICHEM) Site, St. Croix, U.S. Virgin Islands, has been prepared by Golder Associates, Inc. (Golder), on behalf of Berlex Laboratories, Inc. (Berlex) and Pharmacia & Upjohn Company (P&U). The FS Report is submitted in accordance with the requirements of the 1994 Administrative Order on Consent (AOC) entered between the U.S. Environmental Protection Agency (USEPA), Berlex, and others. The FS builds upon the results of the Remedial Investigation (RI) for the Site, conducted principally by Harding Lawson Associates (1995 to 1997) and McLaren/Hart (M/H) (1997 to 2000), as well as a Treatability Study conducted by M/H in Spring 2000. The purpose of the RI/FS process is to gather sufficient information to support informed risk management decisions and enable USEPA to select a remedy that will be protective of human health and the environment, consistent with the National Contingency Plan (NCP). Specifically, the primary objectives of an FS are to: • develop a sound Conceptual Site Model, including the nature, extent, fate and transport of contamination; • support the identification of preliminary remediation goals (PRGs) for the media that have been identified as impacted with constituents of concem (COCs); • develop general response actions (GRAs); • identify, screen, and select remedial technologies and process options applicable to the impacts associated with the Site; and • develop and analyze potential remedial action altematives for the Site. The FS screening and a preliminary evaluation of altematives was conducted and summarized in a Feasibility Study Technical Memorandum (FS Tech Memo) submitted in March 1999 (M/H, 1999). This FS Report includes the results and conclusions of the FS Tech Memo, as modified by USEPA's comments, together with focused development of remedial alternatives and the detailed evaluation ofthese altematives against the criteria contained in the NCP. Golder Associates 400006 I P W June 2001 - 2 - 003-6016 The remainder of the FS Report is organized as follows: • Section 1 provides a brief background of the Site setting, operational history, and regulatory history; • Section 2 provides the Conceptual Site model, including a characterization of the Site- specific and regional geology and hydrogeology. The model includes a discussion of the nature and extent of soil and groundwater contamination at the Site, and summarizes the resulting risks as defined in the Risk Assessment included in the Revised Final RI Report (2000); • Section 3 describes the Remedial Action Objectives for the Site, which are used to develop and evaluate Site-specific remedial altematives. This section also includes a discussion of preliminary remedial goals based on applicable or relevant and appropriate requirements (ARARs) and other "To Be Considered" (TBC) standards; • Section 4 provides a discussion and summary of the general response actions, screening of technology and process options, and development and screening of altematives based upon the previous FS Tech Memo; • Section 5 provides a detailed description of the remedial altematives that were retained for further analysis; • Section 6 contains a listing and brief description of the seven NCP evaluation criteria considered in this FS; and, • Section 7 provides a detailed and comparative evaluation of each of the retained altematives, including analyses against each of the criteria defined in Section 6. Cost esdmates for each altemative are also included. 1.2 Site Description and History Site Description The VICHEM Site is located on Plot 13Q of Estate Bethlehem Middle Works in the south-central portion of St. Croix in the U.S. Virgin Islands (see Figure 1). Site access is via Route 66, which traverses the island east and west and abuts the south-southwest boundary of the Site. The Site is bordered to the north and east by an intermittent stream, the River Gut, which originates north of the Site and drains to the Caribbean Sea. Land use surrounding the VICHEM Site includes a mix of commercial and industrial purposes. A water service company and an undeveloped lot exist immediately to the west and northwest of the Site. A concrete batch plant and two automobile repair shops are locaited east-northeast of the Site, on the opposite side of the River Gut, while two paving companies are located north- Golder Associates 400007 I p w June 2001 - 3 - 003-6016 northwest of the Site across the River Gut. The Henry Rohlsen Airport is situated approximately 1500 feet south of the Site with a prison 0.25 miles to the northwest. Two residential properties are located approximately 0.33 miles north and 0.75 miles northwest of the Site, respectively (M/H, 2000). The VICHEM Site itself was initially developed during the early 1970's and a variety of pharmaceutical manufacturing and blending operations, under a number of different corporate entities, occurred until 1982. However, specific timeframes for the operation of the manufacturing processes are uncertain. In general, toluene, pyridine, and quinidine (chemicals used by many of the occupants) represent the historically largest volume spills or other releases at the Site. The Site is owned by the Charles H. Steffey Holding Corporation and is currently abandoned and overgrown with heavy vegetation. A chain-link fence was installed in Spring 2000 to encompass the Site boundary and secure the area. A layout of the Facility is shown on Figure 2. Several stmctures remain on-site, including: laboratory/warehouse building; maintenance building; nine reportedly empty (M/H, 2000) aboveground storage tanks (ASTs) identified as T-3 through T-11, an unlabeled AST, and eleven concrete pads at former AST locations; production area; stainless-steel and glass reactor areas; loading dock (former location of laboratory pit); concrete storage pad adjacent to the loading dock and next to the scalehouse; cooling towers; generator building; generator and fire pump building; and one 250,000-gallon fire water AST. Two storm drains are located on-site. The Central Storm Drain runs beneath the paved area between the laboratory and maintenance buildings. The Southern Storm Drain, where observed, is a concrete-lined depression along the southern wall of the maintenance building and the edge of the reactor area. Both storm drains discharge to the River Gut (M/H, 2000). Two former production wells, P-1 and P-2, are also located on Site as shown on Figure 3. P-1 was sealed during RI activities in Spring 2000. Further details about the Site, its operational history, and surrounding land and water use are included in the Revised Final Remedial Investigation Report (2000). Golder Associates 400008 I p \ June 2001 - 4 - 003-6016 Site Regulatory History In October 1982, EPA was notified of the facility's impending closure and off-site removal of waste materials. Between 1984 and 1991, several investigations were conducted at the Site by USEPA, Island Chemical Company, and the VICHEM Company. The following six areas of environmental concem were identified through this investigative work: • Laboratory and Warehouse Building; • AST Area; • Former Process Pit (FPP) Area; • Loading Dock/Former Laboratory Pit Area; • Soil Beneath Concrete Pad Near ASTs (northem comer of the Site); and • Concrete Storage Pad (north of the Laboratory and Warehouse Buildings). During the initial assessment stages of the VICHEM Site by the regulatory agencies, several response activities were conducted by both USEPA and Berlex. These activities included soil excavation with on-site treatment (e.g., drying trays) or off-site disposal, drum removals, and off- site disposal of the AST contents ( 2000). The VICHEM Site was placed on the National Priorifies List (NPL) on January 18, 1994. On October 6, 1994, the U.S. Environmental Protection Agency (EPA) entered into an Administrative Order on Consent (AOC), Index No. II CERCLA-94-0401, with Berlex, one of the Respondents to the AOC. Pursuant to Section 106(a) of the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), as amended, 42 U.S.C. §9606(a), the AOC required the performance of a Remedial Investigation/Feasibility Study (RI/FS) at the Site. Golder Associates 400009 I p w June 2001 - 5 - 003-6016 2.0 CONCEPTUAL SITE MODEL Four phases of RI field work took place between 1995 and 2000 to further assess potential impacts in the previously identified areas of concem. The Phase FV RI work was supplemented in Spring 2000 with the abandonment and replacement of former Production Well P-1 (Golder, 2000). Based upon the results of the RI (M/H, 2000 and Golder, 2000), a Conceptual Site Model has been developed that includes the geology, hydrogeology, nature and extent of contamination, and exposure pathways/risks. 2.1 Site Geologic / Hydrogeologic Model Physical Setting The Site is located in the southern lowland valley portion of the River Gut, which is the largest intermittent stream on St. Croix (M/H, 2000) encompassing a drainage area of approximately 11 square miles. The Site falls entirely within the 100-year floodplain of the River Gut, as mapped by the Federal Emergency Management Agency. In the vicinity of the Site, the River Gut extends across the southern plain of St. Croix, and at its confluence with the Bethlehem Gut (located approximately 800 feet to the southeast of the Site), it becomes the Fair Plains Gut. All of the stream channels in the drainage basin are identified as intermittent. The River Gut drains to the Caribbean Sea, via the Fair Plains Gut and Manning Bay, located approximately one mile southeast of the Site. In the vicinity of the Site, topographic ridges are present to the southwest and northeast of the Site. These ridges rise to an elevation of approximately 200 feet mean sea level (MSL). The existing land surface elevation at the Site ranges from approximately 30 feet MSL in the southwestem portion of the Site to approximately 40 feet MSL in the northeastern portion. The land surface bordering the east-northeast Site boundary slopes steeply downward approximately 12 to 15 feet into the River Gut. A comparison was made of present topographic contours to those from 1963 (i.e., prior to Site development). The current ground surface at the Site has been regraded from its original topography by as much as five feet in some areas (e.g., eastem comer of Site and the FPP area). In addition, the relocation of the course of the River Gut is clearly evident. Golder Associates 400010 I p w June 2001 - 6 - 003-6016 Regional Geology and Hydrogeology St. Croix is underlain by rocks of Cretaceous to Pliocene Age. Stmcturally, the island is basically comprised of parallel fault-blocked ridges trending northeast to southwest. Superimposed on these structures is a northeast- to southwest-trending, trough-like sedimentary basin. The older volcaniclastic and igneous intrusive rocks outcrop in the northem and eastem highland areas of the island. The central basin is underlain by the Jealousy Formation (Pliocene), which is overlain by the Kingshill Formation. The Kingshill Formation consists of a carbonate sequence of variable texture and composition. The interbedded lithologies of the Kingshill Formation include a sandy to conglomerate marl composed of terrigeneous material and calcareous skeletal debris, indurated chalks , and calcareous sandstones. The chalks and marls are the dominant lithology types of the Kingshill Formation (M/H, 2000). Recent Alluvial deposits mantle much of the area underlain by the Kingshill Formation. The maximum thickness of the Alluvium is estimated to be approximately 100 feet at the mouth of the River Gut. The Alluvium is composed mostly of montmorillonite clay of low permeability. In certain locations, it is difficult to distinguish the Alluvial clay from the underlying marl of the Kingshill Formation. Interbedded with the clays are thin (two to four feet) lenses of terrigeneous sand and gravel. The coarse material is more prevalent in the river valleys, but the layers of coarse material are isolated and limited in horizontal extent (M/H, 2000). The Kingshill Formation is considered the principal water-bearing deposit on St. Croix. The maximum saturated thickness of the Kingshill Formation is 200 feet, and in some areas, where the entire formafion is screened, it can yield as much as 100 gallons per minute (gpm). In general, however, the Kingshill Formation is a poor-producing formation due to its fine-grained texture and high total dissolved solids (TDS) and chloride content. The Alluvium is tapped by many private and public supply wells and is the principal aquifer in the Fair Plains, Golden Grove, and Adventure well fields. Like the Kingshill Formation, yields within the Alluvium are highly variable. Due to the stratigraphic nature of the Alluvium (i.e., interbedded clay and sands), hydraulic conductivity contrasts between beds result in greater horizontal than vertical hydraulic conductivity, with the Alluvium typically exhibiting confined or semiconfined aquifer conditions. This is especially prevalent in the deeper deposits; whereas the shallow, coarser material found near the River Gut may exhibit unconfined properties (M/H, 2000). Golder Associates 400011 I % p V June 2001 - 7 - 003-6016 Site Geology The Site geology is characterized by approximately 85 feet of fill and Alluvial material overlying the clayey marl of the Kingshill Formation. Figure 3 presents the location of the existing Site monitoring wells and the location of the geologic cross-section. Figure 4 presents a geologic cross-section across the Site and indicates the interpreted original ground surface based on the historic topography and interpreted from the lithologic descriptions contained in boring logs. Much of the fill appears to be reworked natural material and so its composition is very similar to the Alluvium described below. The Alluvium at the Site is comprised of olive brown sandy-clay to sandy-silt, to clayey-sand with occasional amounts of clayey-gravel and sand in the upper 30 to 40 feet. Between a depth of approximately 30 feet to 60 feet, the Alluvium is comprised mainly of a medium brown to gray clay with only occasional trace fine sand and gravel. From approximately 60 feet to 90 feet, the Alluvium consists of silty-clay and sand to medium to coarse sand and clay. A cobble zone was intercepted between an elevation of-3 9 feet MSL and -AS feet MSL in monitoring wells MW-7, MW-8 and MW-9. At each location, this zone appeared to be approximately 2 feet thick. Beneath the Alluvium, the Kingshill Formation was intercepted at several deep borings across the Site including MW-12 and MW-14. At these locations, the contact between the Alluvium and the Kingshill Formation is not well defined, however below approximately 100 feet bgs, the Kingshill Formation is described as a light brown to white clay. Site Hydrogeology The water table is typically encountered approximately 10 to 30 feet below ground surface and is subject to significant fluctuation due to seasonal changes and precipitation. Based on the groundwater data presented in the Revised Final RI Report (2000) there are two distinct water bearing zones within the Alluvium. The hydrographs presented in Figures 5 and 6 present data collected at shallow/deep well pairs MW-2 and MW-7 in the FPP Area, and MW-6 and MW-8 in the AST Area. Hydrographs for these well pairs are presented for the period from lanuary 22, 1998 to Febmary 11, 1998. At each location, the hydrograph for the deeper wells (i.e., MW-7 and MW-8) clearly show a response to off-site pumping, which appears to cycle on and off on a daily basis. In contrast, the shallow wells at each location show a general decline in head over the monitoring period, but with no response to pumping. Similarly, during the development of deep well MW-9, no drawdown was observed in the adjacent shallow well MW-4 (M/H, 2000). This information demonstrates that the Alluvial clay acts as an aquitard such that the upper and lower water bearing zones within the Alluvium are not in hydraulic communication within the Site area. Golder Associates 400012 I P W June 2001 - 8 - 003-6016 Interpreted groundwater elevation contours for the shallow and deep Alluvium (October 21, 1998), as presented in the RI Report, are shown in Figures 7 and 8. For comparison, interpreted groundwater elevation contours for more recent data, under high groundwater conditions, are shown on Figure 9 (January 31, 2000), and Figure 10 (March 6, 2000). These figures show the predominant flow direction within the upper Alluvium is generally southward in the central part of the Site, consistent with the results of earlier RI investigations. As indicated in Figures 9 and 10, in the immediate vicinity of the AST area, flow is inidally towards the east and south away from the vicinity of MW-6. The easterly component of flow is not significant and likely only results in an easterly groundwater flow component of approximately 100 to 150 feet before the predominant south-southeasterly flow direction retums. It is notable that this easterly flow direction does not occur under the highest groundwater conditions (i.e., November 30, 1999), or for the majority of measured events presented in the RI Report, indicating that this is a transient phenomenon. Interpreted groundwater elevation contours for the deep Alluvial zone are shown on Figure 11 (March 6, 2000). This figure shows a flow potential within the deeper Alluvium as generally southeasterly. The previous RI investigations indicate that the deep zone exhibits a generally southerly flow potential, similar to that of the shallow zone (M/H, 2000). Horizontal hydraulic gradients in the upper Alluvium in the AST area ranged from approximately 0.002 feet per foot [ft/ft] to 0.008 ft/ft, with an average value of 0.006 ft/ft. hi the FPP area, horizontal hydraulic gradients ranged from 0.009 ft/ft to 0.014 ft/ft with an average of 0.012 ft/ft. Horizontal hydraulic gradients within the lower Alluvium were slightly lower ranging from 0.003 ft/ft to 0.014 ft/ft. Vertical hydraulic gradients between the upper and lower Alluvium are consistently downward. In the AST area, the vertical hydraulic gradients ranged from -0.005 ft/ft to -0.09 ft/ft. hi the FPP area, the vertical hydraulic gradients ranged from -.008 ft/ft to -0.11 ft/ft. Slug testing was completed in numerous wells at the Site throughout various phases of the RI in the shallow and deep Alluvium, and the Kingshill Formation. Within the AST area, the geometric mean hydraulic conductivity on the shallow Alluvium is 6.3x10'^ cm/sec, and in the FPP area, the geometric mean conductivity is 5.9x10"'' cm/sec for the same unit. Golder Associates 4 0 0 0 1 3 I P W June 2001 - 9 - 003-6016 In summary, the Site hydrogeology is characterized by the presence of a largely unconfined to semi-confined shallow (uppermost) Alluvium aquifer with a predominant flow direction to the south-southeast. Underlying the shallow aquifer is an aquitard or aquitards, comprised of a stiff clay which confines the lower Alluvium and acts as a significant hydraulic barrier isolating the upper Alluvium from the lower Alluvium aquifer and the underlying Kingshill Formation. The lower Alluvium aquifer exhibits a predominant flow direction to the southeast. 2.2 Nature and Extent of Contamination Soil samples from approximately 100 borings and groundwater samples from about 45 temporary and permanent wells were analyzed for Target Compound List Volatile Organic Compounds (VOCs) and Semi-volatile Organics (SVOCs), Target Analyte List metals, and field parameters during the RI. The following sections summarize the nature and extent of contamination, defined by this program. Discussion is focused on those constituents that exceed background, USEPA Soil Screening Level (SSL) concentrations' or risk-based concentrations (RBCs) where SSLs have not been established, for soil and Maximum Contaminant Levels (MCLs) for groundwater. A more comprehensive presentation and analysis of all detected concentrations is contained in the RI Report. Areas of concem originally identified for the Site included the Former Laboratory Pit Area and Former Dmm Areas; the RI data established that these areas were not in fact impacted. 2.2.1 Soil Quality Surface soil in the AST Area shows evidence of VOC contamination at relatively low levels (e.g., 30 ppb). Subsurface Soil in the AST Area is impacted by ethylbenzene and xylenes at depths up to 24 feet below ground surface (bgs). Concentrations of ethylbenzene and xylenes exceeded MGW SSLs. The portion of the AST Area impacted by ethylbenzene and xylenes in subsurface soil is shown on Figure 12, where the majority of the contamination is located in the former vicinity of Tanks 7, 8, and 9 Shallow soil samples from the FPP Area are not impacted, however, chloroform was detected at levels up to 410 ppb (estimated values) in soil samples between 21 ft to 27 ft bgs at or below the groundwater table. The assumed zone of chlorofonn impacts in the FPP Area encompasses a 5- foot interval (approximately 20 to 25 feet bgs) within a 400 square-foot surface area (M/H, 2000). Golder Associates 400014 I p w June 2001 -10- 003-6016 Pentachlorophenol and isophorone were also detected in surface soils above the MGW SSL. However, pentachlorophenol was not detected in groundwater and was not consequently considered to be of concem. Isophorone, which was detected in the Southern Storm Drain above the MGW SSL, was eliminated as a surface soil concem in the Human Health Risk Assessment (HHRA) because of its minor contribution to carcinogenic/non-carcinogenic risk for exposure to groundwater (M/H, 2000). Methylene chloride concentrations previously reported in Site soil samples are artifacts resulting from blank contamination (laboratory method blanks, field blanks, and trip blanks) and do not represent field conditions. Therefore, methylene chloride should not be considered a Constituent of Concem (COC) for the Site. A detailed explanation follows: • In past data validation reports, blank action levels were not properly calculated. The blank action levels must include trip blanks and field blanks in addition to method blanks. Previous data validators attempted to isolate samples by method blanks and did not use the other quality control (QC) blanks in calculating action levels. Since methylene chloride and acetone are common laboratory contaminants, it is inappropriate to rely on one method blank for assessing potential contamination. • Previously, blank action levels were not applied correctly. Many soil and groundwater samples were highly diluted due to concentrations of other constituents in the sample matrix. In such cases, the data validator must adjust the blank action levels by the dilution factor. Since this was not done, blank contaminants were erroneously reported as detected constituents in these samples. • Previously, results attributable to blank contamination were not properly qualified. In accordance with USEPA Region II data validation Standard Operating Procedures (USEPA 1996), results that are attributable to blank contamination should be qualified as non-detect ("U") and treated as such. Results below the sample quantitation limits (SQLs) should be changed to the SQL and qualified as U. Results above the SQL are not changed and are qualified as U. In either case, the constituent should have appropriately been considered as undetected in the sample. The methylene chloride and acetone data presented in the Final RI Report (M/H, 2000) showed results below the Contract Required Quantitation Limit that were neither changed to the SQL nor correctly qualified. Qualifiers of "BJ", "B" or simply "J" were used rather than the correct qualifier, which is "U." Examination ofthese data by Golder revealed that methylene chloride is not present in groundwater or soil, and that acetone detections are limited to low levels. Acetone ' SSLs were established using a Dilution and Attenuation Factor (DAF) of 20 in the RI, subsequent comparisons use a DAF of 10 as agreed with USEPA. Subsurface soil data was also compared to Migration to Groundwater (MGW) SSLs. Golder Associates 400015 I p w June 2001 - 1 1 - 003-6016 was detected in thirteen samples at concentrations ranging from 17 ppb to 580 ppb. However, these data are below the soil screening level and acetone should therefore not be considered a COC for the Site. Regardless, the inclusion or exclusion of acetone and methylene chloride data does not materially affect the Risk Assessment results. Background levels of arsenic in surface soil range from 0.7 parts per million (ppm) to 1.3 ppm. In general, arsenic detections in surface soil, soil/sediment from the Gut System, and subsurface soil samples were consistent with the background screening criterion of 1.64 ppm except for two surface soil samples from the Central Storm Drain that had arsenic at 3.7 ppm and 8.8 ppm. These levels (including background) exceed the arsenic soil screening level (SSL) for ingestion of 0.4 ppm. Arsenic also exceeded this SSL (at a concentration of 0.87 ppm) in the Southern Storm Drain. Background levels of chromium in surface soil range from 9.8 ppm to 13.6 ppm. In general, chromium detections in surface soil samples did not exceed the background screening criteria except for a sample from the Central Storm Drain that contained chromium at 32 ppm. The detected concentrations of chromium, however, did not exceed any SSLs. Surface soil samples in some areas of the Site (e.g., the AST Area) exhibited concentrations of iron and manganese (naturally occurring minerals) greater than background levels. As noted in Section 2.1, some areas of the Site contain fill which was used for regrading. However, since fill had not likely been placed in the areas where background samples were collected during the RI, background fill concentrations of iron and manganese are not known. Several samples exceeded the MGW SSL for iron and manganese. Other metals detected in surface soils and which were classified as COCs include vanadium and zinc. Based on a comparison to MGW SSLs and groundwater data, no SVOCs or metals detected in subsurface soils were considered to be of significant concem. 2.2.2 Groundwater Quality In general, the following VOCs were detected above Maximum Contaminant Levels (MCLs) in groundwater: ethylbenzene, total xylenes, and chloroform. Several metals (antimony, arsenic, Golder Associates 400016 I p w June 2001 -12- 003-6016 barium, chromium, iron, lead, manganese, vanadium) were detected in groundwater but did not generally exceed MCLs (M/H, 2000). Shallow groundwater in the AST Area exhibits contamination by ethylbenzene and xylenes in excess of MCLs. Groundwater isoconcentrations for the 1998 data (reflecting the maximum concentrations detected) are provided on Figures 13 and 14. Current concentrations are reduced, as measured in the Spring 2000 sampling event, and are noted on the figures. Shallow groundwater in the FPP area contains chloroform at concentrations in excess of MCLs^. Groundwater isoconcentrations for the 1998 data (reflecting the maximum concentrations detected) are provided on Figure 15. Current concentrations are generally lower, as measured in the Spring 2000 sampling event, and are noted on the figure. Concentrations up to 4 ppm were detected in a geoprobe sample located near the Former Process Pit in 1998. Shallow well MW-2, in the same area, exhibited a chloroform concentration of 2.4 ppm during the March 1998 sampling event. However, the current concentration of chloroform in this well, as measured during the Spring 2000 event, was two orders of magnitude lower. In the deep Alluvial groundwater, MCLs have not been exceeded at any wells. No SVOCs have been detected in the .deep Alluvium or the Production Wells P-1 and P-2. The Kingshill Formation groundwater, characterized by wells MW-12 and MW-14 and Hydropunch samples, does not exhibit concentrations of any Site Target Compounds above MCLs. Arsenic has been sporadically detected in groundwater on Site. The March and January 1998 sampling events were the most recent events in which metals samples were collected. During these events, arsenic was detected in wells MW-3, MW-7, and upgradient well MW-10^, with the highest concentration in MW-10. Arsenic levels did not exceed the MCL of 50 ppb. Likewise, the highest concentrations of chromium and lead during the January and March 1998 sampling events were detected in upgradient well MW-10. Total lead was detected above its Treatment Technique Action Level (TTAL) of 15 ppb twice in MW-5, at concentrations of 17 The MCL for total trihalomethanes is 100 ppb. In the 1994 Proposed Rule for Disinfectants and Disinfection By- products, a total THM number of 80 ppb was proposed. In the Final RI Report, a value of 80 ppb was used as the screening criteria. References to "upgradienf well MW-10 here and elsewhere signify that MW-10 was upgradient at the time of sampling, based on water level measurements taken at the time of the sampling event. Golder Associates 4 0 0 0 1 7 I P W June 2001 - 1 3 - 003-6016 and 20 ppb. Total lead was also detected above the TTAL in one sample at MW-10, at a concentration of 50.7 ppb. However, lead was not detected in monitoring wells MW-1 and MW- 6 during the same sampling event. Antimony was quantified at 6.2 ppb in one sample at MW-6, which is slighfly above the MCL of 6 ppb. No other samples exceed the MCL for antimony. 2.3 Natural Attenuation 2.3.1 General The reduction in contaminant mass, concentration, volume, mobility or toxicity which has been identified as the basis of the natural attenuation of contaminants in groundwater can occur through a number of physical, chemical and microbiological processes. The dominant attenuating process within a contaminant plume will depend on given site conditions and on the interaction of the major contaminant with other co-existent contaminants. The term 'natural attenuation' is, however, commonly used interchangeably with the idea of biodegradation and the remediating effects of microbes. Specific lines of evidence are assessed to determine the extent of natural attenuation at a particular site. These include comprehensive site wide analysis of the biogeochemistry of the groundwater system and fate and transport modeling studies to confirm and quantify the rates of remediation by natural attenuation. The following natural attenuation analyses have been performed for the VICHEM Site: • An evaluation of natural attenuation processes within the aquifer to delineate areas of aerobic and anaerobic conditions, and identify the natural attenuation mechanisms occurring within the aquifer using natural attenuation indicator parameter data from site- specific sampling; A trend analysis of select constituents to document the decrease in concentrations over time at locadons both downgradient of the Site as well as near source areas; and. Solute transport modeling, using 1- and 2-dimensional (ID and 2D) analytical models, to estimate contaminant mass reductions with time downgradient of the contaminant sources. The following sections provided an analysis of each ofthese three lines of evidence. Golder Associates 400018 I P ^ June 2001 -14- 003-6016 2.3.2 Assessment of Natural Attenuation Processes Aromatic Compounds Biodegradation Mechanisms: ASTArea The biodegradation of petroleum hydrocarbons (e.g., ethylbenzene and xylene) occurs through their use by microorganisms as primary substrates (sources of carbon and energy). During the metabolism process, electrons are transferred from the hydrocarbon to facilitate the release of energy. The hydrocarbon is therefore termed an "electron donor". The process also requires an "electron acceptor" for the transferred electrons, and nutrients such as nitrate or phosphate. Typical electron acceptors are oxygen, nitrate, iron III, sulfate, and carbon dioxide, which are utilized strictly in that order. Under some circumstances, manganese FV or chlorinated solvents may also be used as electron acceptors. The degradation of petroleum hydrocarbons occurs most effectively under aerobic (oxygen reducing) conditions, and reaction efficiency reduces significantly down the scale of electron acceptors. Howard et. al., 1991 provide aerobic half-lives for the Site constituents xylene and ethylbenzene of 3 to 10 days and 7 to 28 days, respectively. The efficient biodegradation of petroleum hydrocarbons has been commonly considered not to occur under anaerobic (particularly sulfate reducing and methanogenic) conditions, although it is now becoming recognized that in terms of total mass removal, the slower but more prevalent anaerobic degradation processes may be significant. The degradation process is limited by the supply of electron acceptors, but since these are generally present in abundance in the natural environment, the biodegradation of petroleum hydrocarbons under anaerobic conditions typically proceeds to complete degradation to non-toxic by-products. Howard et. al., 1991 provide anaerobic half-lives for the Site constituents xylene and ethylbenzene of 176 to 228 days and 182 to 365 days, respectively At the AST Area, the aromatic hydrocarbons are susceptible to degradation under aerobic and anaerobic conditions. Toluene, xylene and ethylbenzene are the most bioavailable of the BTEX compounds to act as substrate, and in fact are degraded at appreciable rates and quantities within the plume boundary. The degree to which all natural attenuation mechanisms (dispersion, dilution, sorption and biodegradation) contribute to plume containment at the AST Area is significant, based on a plume that has been delineated by 5 years of sampling, (see Figures 14 and 15) and whose overall length is only of the range of 120 feet to 150 feet even though the plume may be more than 20 or so years old. Based on the hydraulic characterization, ethylbenzene Golder Associates 4 0 0 0 1 9 I p w June 2001 - 1 5 - 003-6016 and xylene subject to sorption but not biodegradation would have traveled 688 feet, if the plume were assumed to be 20 years old. Chlorinated Solvents Biodegradation Mechanisms: FPP Area The process of biodegradation of chlorinated solvents can occur in three ways: • Where the chlorinated solvent acts as electron donor. Under aerobic and occasionally under ferric iron reducing conditions, this is the primary mechanism for the biodegradation of the less chlorinated solvents in the field but is not considered to be effective for the more highly chlorinated compounds such as PCE or Chloroform. The oxidation of vinyl chloride is the only known example of chlorinated solvents acting as an electron donor under anaerobic conditions; • Where the chlorinated solvent acts as electron acceptor. In this process, known as reductive dehalogenation, chlorine atoms are replaced sequentially with hydrogen atoms so that, for example, carbon tetrachloride degrades to chloroform, which degrades further to dichloromethane. [Note: half-lives for reductive dehalogenation of carbon tetrachloride and chloroform are estimated at 7 to 28 days, Howard et.al., 1991] Reductive dehalogenation is the most important process for the natural biodegradation of the more highly chlorinated solvents, and occurs best under reducing conditions (sulfate reducing and methanogenic, and occasionally iron III or nitrate reducing conditions). Reductive dehalogenation also occurs for the less chlorinated solvents (dichloromethane is known to degrade to chloromethane and then to methane via this pathway at half-lives of 1 to 4 months, Howard et.al., 1991); and • Where the chlorinated solvent is degraded fortuitously by an enzyme or co-factor produced during the microbial metabolism of another compound (co-metabolism). The co-metabolic process is described as slow and incomplete, and may be limited under natural conditions although dichloromethane and chloromethane have been noted as readily and very efficiently co-metabolized under aerobic conditions. [Note: half-lives for aerobic cometabolism of dichloromethane and chloromethane are estimated at 7 to 28 days, Howard et.al., 1991] At the FPP Area of the Site, chloroform is the primary constituent of concem, with only an occasional historic detect of BTEX compounds at low levels (<10ug/L), and no BTEX detections during air sparge test sampling in the Spring of 2000 (see Draft SVE/AS Pilot Study Report, Golder, October 2000). For the FPP area, concentradons of chloroform appear to be diminishing very rapidly in the anaerobic and reducing groundwater environment that is present at this area of the Site. The mechanism for biodegradation of the chloroform in this area is most likely a reductive dehalogenation process. The degree to which all natural attenuation mechanisms (dispersion, dilution, sorption and biodegradation) contribute to plume containment at the FPP Area is significant, based on a plume that has been delineated by 5 years of sampling, (see Figure 15) and whose overall length is only of the range of 80 feet to 100 feet, even though the plume Golder Associates 400020 I June 2001 16 003-6016 may be more than 20 or so years old. Based on hydraulic characterization, chloroform subject to sorption but not biodegradation would have traveled 457 feet, if the plume were assumed to be 20 years old. Natural Attenuation Indicator Parameters As described in Section 1.1, the evaluation of natural attenuation involves the interpretation of several key chemical and geochemical parameters. In addition to the VOC data typically available for sites, select "natural attenuation indicator" analytical parameters are collected as part of the groundwater sampling effort to demonstrate the degree to which natural attenuation is occurring at the Site. The following focused list of natural attenuation indicator parameters to be assessed was developed by Golder for the Site using Site-specific information, the information from studies provided by the United States Environmental Protection Agency (USEPA, 1999), and industry guidance on the evaluation of natural attenuation (Wiedemeier, 1997). The natural attenuation indicator parameters are listed below: P \ Parameter Primary spill contaminants Degradation products of primary spill contaminants Dissolved Oxygen (DO) Eh Total Organic Carbon Nitrate Nitrite Iron III Indication/Reason Assists in the delineation of the contaminant plume and contaminant concentrations. Evidence for the biodegradation of the primary contaminant. Dichloromethane is an indicator of chloroform degradation. Similarly, the ratio of o-xylene to the m and p isomers would be expected to increase as BTEX degrades. The electron acceptor most thermodynamically favored by micro- organisms for the degradation of natural or anthropogenic organic carbon. Concentrations less than 1 mg/1 generally indicate an anaerobic environment. At DO greater than about 0.5 mg/1 anaerobic bacteria generally cannot function, and reductive dehalogenation of chlorinated solvents is unlikely to occur. It will not occur at concentrations greater than 1 mg/1. Petroleum hydrocarbons and vinyl chloride may be oxidized aerobically at DO concentrations in excess of 1 mg/1. Indicates the redox state of the groundwater and hence the types of attenuation processes which may occur. <-F50 mV indicates reductive pathway is possible. Carbon and energy source for aerobic respiration and electron donor' for anaerobic reductive dechlorination. Substrate for microbial respiration (electron acceptor) if oxygen is depleted. At concentrations in excess of 1 mg/1, nitrate may compete with reductive pathway. Results from nitrate reduction (denitrification). An analysis of biologically available iron III can be used to estimate the potential for attenuation where iron III is reduced. Iron III may be used as an electron acceptor during anaerobic degradation of electron donors where dissolved oxygen and nitrate are depleted. Golder Associates 400021 I June 2001 17- 003-6016 Iron II Sulfate Sulfide Methane/Ethane/Ethene Iron II may indicate the anaerobic biodegradation of petroleum hydrocarbons where dissolved oxygen, nitrate and manganese are depleted (iron III is used as an electron acceptor), although precipitation when combined with other substances may lead to an underestimate of the quantities produced. At concentrations greater than about 1 mg/1, reductive pathway is possible. Substrate for anaerobic microbial respiration (electron acceptor). At concentrations in excess of 20 mg/1, sulfate may compete with reductive pathway. Results from sulfate reduction. At concentrations greater than about 1 mg/1, reductive pathway is possible. May not be detected even if sulfate-reducing bacteria are active because it can react with various oxygenated chemical species and metals. Indicators of complete dechlorination of spill solvents. Methane is produced under methanogenic conditions (Eh < -240 mV) from BTEX degradation, and is the end product of degradation of the chloromethane sequence. Ethane and ethene are produced from chlorinated ethane and ethene degradation. p Geochemical parameters were sampled during RI sampling events (M/H,2000), and during air sparge testing during the Spring of 2000. The Spring 2000 data are included in the Draft SVE/AS Pilot SUidy Report (Golder, 2000). Natural Attenuation Indicator Parameters: ASTArea Dissolved Oxygen (DO) For the shallow monitoring wells (MW-1 and MW-6), DO concenfrations ranged from 0.24 mg/L to 0.52 mg/L prior to sparge testing, which is indicative of oxygen consumption. Post-sparge testing of samples in MW-1 showed a significant increase in DO (from 0.41 mg/1 to 9.64 mg/1), implying that the groundwater in the impacted area of the AST plume is indeed under-saturated with respect to DO and that the sparge test was successful in adding this electron acceptor. Oxidation-Reduction Potential (Eh) Eh measurements for the shallow monitoring wells were reported as ranging from - 291mV to +52 mV prior to sparge testing, indicating sfrongly reducing (or anaerobic) conditions. These values characterize the aquifer conditions as an iron reducing to sulfate reducing environment. w Total Organic Carbon (TOO TOC in AST area soils ranges from 1650 mg/kg to 23,000 mg/kg (M/H, 1999). No AST area groundwater samples have been analyzed for TOC, though these high soil concentrations are indicative of available carbon substrate for aerobic respiration. Golder Associates 400022 I p w June 2001 -18- 003-6016 Nitrate/Nitrite Nitrite (a by-product of nitrate reduction) was not detected in shallow wells at the AST area. Ferrous Iron (Fe ) Ferrous iron (a by-product of ferric iron reduction) was observed in both shallow wells (MW-1 and MW-6) at 0.9 mg/1 and 3.1 mg/L, respectively, prior to sparge testing. As supported by the corresponding Eh conditions (see above), iron reduction may be a significant biodegradation mechanism at the Site. Sulfate/Sulfide Sulfate concenfrations in the contaminated areas show markedly lower concentrations than background. Prior to sparge testing, in MW-10 (a background well), sulfate was detected at 286 mg/L, while in MW-1 and MW-6, sulfate was non-detect and 47 mg/L, respectively, indicating significant sulfate reduction occurring in the AST contaminated area. Sulfide (a by-product of sulfate reduction) was detected in both shallow wells (MW-1 and MW-6) at 0.51 mg/1 and 0.11 mg/L, respectively,. As presented in Section 1.2.2, the efficient biodegradation of pefroleum hydrocarbons is commonly considered not to occur under anaerobic (particularly sulfate reducing and methanogenic) conditions, although it is now widely recognized that in terms of total mass removal, the slower but more prevalent anaerobic degradation processes are significant. Along with the sulfide detections. Eh conditions (-291 mV to -275 mV) at wells MW-1 and MW-6 indicate that sulfate reduction is likely an anaerobic biodegradation mechanism at the AST area. Methane/Ethane/Ethene Light hydrocarbon analyses have not been performed at the AST area of the Site. Natural Attenuation Indicator Parameters: FPP Area Dissolved Oxvgen (DO) For the shallow monitoring wells (MW-2, MW-3, MW-11 and MW-13), DO concentrations ranged from below detection to 2.22 mg/L prior to sparge testing, which is indicative of oxygen consumption. The single post-sparge testing sample in a shallow well (MW-2) showed a marked increase in DO (from 0.36 mg/1 to 3.04 mg/1), implying that the groundwater in the impacted area of the FPP plume is indeed deficient in DO and that the sparge test was successful in adding this electron acceptor. Golder Associates 400023 J I P W June 2001 -19- 003-6016 Oxidation-Reduction Potential (Eh) Eh measurements for the shallow monitoring wells were reported as ranging from -120 mV to +63 mV prior to sparge testing, indicating reducing (or anaerobic) conditions. These values characterize the aquifer conditions as an iron reducing to sulfate reducing environment. Total Organic Carbon (TOC) TOC ranges from 3.4 mg/L to 4.4 mg/L (RI Report). These concentrations are acceptable for sustaining reductive dechlorination with TOC acting as a carbon and energy source. Nitrate/Nitrite Nitrite (a by-product of nitrate reduction) was detected in one shallow groundwater sample (MW- 2) at a concentration of 0.01 mg/L in the FPP area of the Site, coincident with the area of highest chloroform concenfration. Nifrate was lower (potentially indicating nitrate consumption) in the three shallow wells (MW-2, MW-3 and MW-11) within the impacted plume area compared to those wells outside the plume at the FPP area. Ferrous Iron (Fe^ ) Ferrous iron (a by-product of ferric iron reduction) was observed in one shallow well (MW-3) at 4.6 mg/L, prior to sparge testing. In 1998, dissolved iron (an indicator of ferrous iron) was reported ranging from 0.18 mg/1 to 1.25 mg/1 in shallow wells. As supported by the corresponding Eh conditions (see above), iron reduction may be the most significant biodegradation mechanism at the Site. Sulfate/Sulfide Sulfate concenfrations in the shallow contaminated areas are moderately lower than background concentrations and at the fringe of the plume. In MW-3, MW-11, and MW-13, which are background and plume fringe wells, sulfate was detected at 182-243 mg/L, while in MW-2, a shallow source area well, sulfate was detected at 151 mg/L, suggesting sulfate reduction may be occurring. Sulfide (a by-product of sulfate reduction) was detected in MW-2 at a concenfration of 0.02 mg/L in the FPP Area, coincident with the area of highest chlorofonn concenfration. Methane/Ethane/Ethene Light hydrocarbon analyses have not been performed at the FPP area of the Site. Golder Associates 400024 • p w June 2001 -20- 003-6016 2.3.3 Trend Analysis Figures 16 and 17 provide the time trends for VOC contamination at the FPP and AST areas, respectively. As shown on Figure 16, chloroform has significantly decreased in the FPP near source area well MW-2, from 5990 ug/1 in 1996 to three measurements less than or equal to about 40 ug/1 in the Spring of 2000 (37, 40.7 and 21.1 ug/1, respectively). Downgradient, at MW-11, data only exists since 1998, showing a slight increase in chloroform from 3 ug/1 to 40.4 ug/1. Two-dimensional modeling suggests that such minor increases can occur under transient conditions (see Section 2.3.4). Importantly however, of the twenty-eight (28) samples taken in the FPP area since January 2000 (including duplicates), all but one are below 100 ug/l'*. Only VMP-ID (sparge test monitoring probe) in the source area had a concenfration of 137 ug/1 on May 1,2000. Concentrations of the principal VOCs in the AST area (ethylbenzene and xylene) are shown on Figure 17^. Of particular interest is the sharp decline in VOC concentrations at MW-1 in response to the SVE/AS test conducted in April 2000. Concenfrations of total xylenes in groundwater decreased from 108,000 ug/1 to 8,700 ug/1, then rebounded after testing to 40,100 ug/1. For ethylbenzene, concentrations decreased from 21,600 ug/1 to 1,040 ug/1, then rebounded after testing to 7,680 ug/1. These results imply that in the AST Area, where the permeabilities allow for vapor fransfer, significant improvement in the groundwater conditions can be achieved by sparging and vapor phase extraction as well as by the infroduction of oxygen to permit the faster aerobic biodegradation mechanism. 2.3.4 Fate and Transport Modeling To assess whether the groundwater constituents at the Site have reached a steady state condition as a result of mass removal by natural attenuation, solute fransport analysis was performed. The objective of solute fransport analysis is to evaluate the contribution of biodegradation to the overall attenuation rate. This is accomplished by using an analytical solution that represents advection, dispersion, sorption, dilution, and decay (biodegradation). Analyses have been conducted for: •* The MCL for total trihalomethanes is 100 ug/1. The proposed THM limit of 80 ug/1 is only exceeded in one additional sample at the same location. ^ The first two sample dates for MW-1 are qualified E&D indicating that the instmment calibration range was exceeded for a diluted sample; these results may therefore be underestimated. Golder Associates 400025 I p w June 2001 - 2 1 - 003-6016 • Ethylbenzene and total xylenes in the AST area, and • Chlorofomi in the FPP area. One-Dimensional Solute Transport Modeling (de Marsily) The analytical model selected for this evaluation is presented in "Quantitative Hydrogeology" prepared by de Marsily (1986). The solution of the one-dimensional advection-dispersion equation for groundwater flow and solute transport utilized accounts for degradation of the constituents by natural attenuation (a first order reaction rate for the sum of natural chemical and biological processes). The parameter used to estimate the rate of degradation is the half-life time (i.e., the amount of time it takes for the concenfration of a compound to decrease by one-half due to degradation processes). The solution appropriately accounts both for constituents released into the groundwater (mass increase) and constituents treated through natural attenuation processes (mass decrease). Steady state conditions occur when the mass of constituents dissolved into groundwater at the source is balanced by the mass removed, or treated, through natural attenuation processes. Following de Marsily (1986), a one-dimensional case is chosen to model the concentration of a constituent in a semi-infinite medium. The goveming equation is: '—Y-U—^coR{ ox dx dt (1) where: C = concenfration (ug/L); t = time (days); X = distance (feet); U = Darcy velocity (considered constant for one-dimensional flow) (feet'day); D = the dispersion coefficient (considered constant, using only longitudinal dispersion for one-dimensional model) (ft^/day); (o = porosity; R = the retardation factor of the constituent due to adsorption; and, A = the coefficient of exponential decay (day"'). Here, X is determined from: C = Co/2 = Coexp(-/l ti/2) Golder Associates 400026 I June 2001 where: Co tl/2 22- 003-6016 initial concenfration; and, half-life of constituent; The solute fransport model input parameters are Darcy velocity, porosity, dispersion coefficient, retardation factor, bulk density, and half-life time. Site-specific hydrogeologic and fate and fransport parameters used in the analysis are listed in the following tables, along with the source of the data: ASTArea: P w Parameter Hydraulic Conductivity, K Hydraulic Gradient, I Effective porosity, n^ Seepage velocity, v Value 6.3 X 10' 0.006 20 196 Units cm/sec ft/ft % ft/yr Source Section 2.1 Section 2.1 Estimate for sandy clayey silts v = Ki/ne FPP Area: Parameter Hydraulic Conductivity, K Hydraulic Gradient, I Effective porosity, n^ Seepage velocity, v Value 5.9 X 10"'* 0.012 20 36.6 Units cm/sec ft/ft % ft/yr Source Section 2.1 Section 2.1 Estimate for sandy clayey silts v = Ki/n, Chemical Information: Parameter K„c (L/Kg)' foe ( - ) • Soil Density, (g/ml)^ Bulk pb Retardation Coefficient, R^ (-) Chloroform 31 Ethylbenzene 240 Total Xylenes 240 0.0027 0.0027 0.0027 1.44 1.44 1.44 1.6 5.7 5.7 'USEPA, 1986 ^M/H 2000 (RI) 'R = I + Koc*foc*pb/n A starting point for estimating longitudinal dispersivity, aL, was determined using the well- known formula by Xu and Eckstein (Xu and Eckstein, 1995) which is dependent on the plume length. In the AST area, QL was modified to reflect the hydrogeology of the AST area in which Golder Associates 400027 I p w June 2001 - 2 3 - 003-6016 groundwater direction likely changes in response to seasonal or climatic variations in rainfall, drought conditions, etc. This variability increases the "smearing" of the plume front, thus, in effect, increasing the aL value. A value of 50 ft was used for aL in the AST area. The Xu and Eckstein formula was used in the FPP area and the calculated value for aLwas 10.4 ft, assuming a plume length of 180 ft. Models were calibrated utilizing the October 1998 RI data. Calibration of the rtiodel consisted of iteratively fitting the model predictions to field measurements using the degradation half-life as the fitting parameter and assuming steady-state conditions. The model produces a centerline concentration output chart, depicting concentration over distance at a given time. This concentration profile was compared to the field values and adjusted accordingly until the best fit, using engineering judgment, was achieved. Figures 18 and 19 provide the results of xylene modeling and Figures 22 and 23 provide results for ethylbenzene modeling. Figures 22 and 23 provide the results of chloroform modeling. The simulations resulted in the following calibrated half-lives: • xylene 150 days; • ethylbenzene 100 days; and,. • chloroform 100 days. These values are consistent with literature values (see Section 1.2), and indicate a significant attenuation rate for both Areas of the Site. As shown on Figures 19, 21, and 23, the distance at which applicable Site remediation standards (MCLs) are met were estimated by interpreting the distance from a source area point (i.e., MW-6 for the AST Area and GWPP-27 for the FPP Area) at which the concentration curve intersects the concenfration represented by the MCL for that compound. The MCLs that are used as point of compliance target concentrations are 700 ug/L for ethylbenzene, 10,000 ug/L for total xylenes and 100 ug/L for chloroform. As discussed above, the 1-D model was used to initially solve for the decay rate rather than the distance to compliance, based on field data. Golder Associates 400028 I p V June 2001 -24- 003-6016 Based on the results of 1-D modeling, the distance at which compliance is attained for each COC is as follows: • xylene 110 ft; • ethylbenzene 125 ft; and, • chloroform 60 ft. For comparison, in the AST Area, the Site boundary (at Route 66) in the direction of groundwater flow is approximately 300 feet. Historical analytical results in the AST Area show evidence of groundwater contamination approximately fifty feet beyond the Site fenceline immediately adjacent to this Area in the "upgradienf direction. This may be the result of historical seasonal variations in groundwater flow (i.e., temporary flow gradients to the northeast). To account for this possibility, the input parameter for longitudinal dispersivity was modified as discussed above. The compliance distances listed above are applicable to the predominant direction of groundwater flow. In the FPP Area, the Site boundary (assumed coincident with the fenceline) in the direction of groundwater flow, is approximately 100 feet. Two-Dimensional Solute Transport Modeling (Bioscreen) To further assess whether the groundwater constituents at a site are undergoing biodegradation of mass, 2-D solute transport analysis was performed. The objective of this 2-D solute fransport analysis is to evaluate the confribution of biodegradation to the natural attenuation mechanisms believed to be occurring at the Site as well as to verify the results of 1-D modeling. The primary objectives of this modeling effort are to: • constmct a calibrated model based on Site-specific information and conservative assumptions that can be used to simulate the natural attenuation of the COCs; • using the calibrated model, estirhate the distance at which COCs would naturally attenuate to levels below regulatory benchmarks; • using the calibrated model in a transient analysis, estimate the mass of source COCs present at the Sites; and. • using the calibrated model in a transient analysis, predict the time to compliance for the entire plume length. The model used for this exercise is Bioscreen - Natural Attenuation Decision Support System: Version 1.4 (USEPA 1997). The Bioscreen model is endorsed by the U.S. Environmental Golder Associates 400029 I % p w June 2001 - 2 5 - 003-6016 Protection Agency (EPA) Center for Subsurface Modeling Support (CSMoS) (http://www.epa.gov/ada/ csmos.html). The Bioscreen model is considered especially useful in screening-level modeling for dissolved hydrocarbons and similar-type organic chemicals. The model is based on the same analytical equation for advection, dispersion, adsorption, and decay of constituents in groundwater as was used in the 1-D modeling. Bioscreen requires infonnation about Site hydrogeology, dispersion/dispersivity, adsorption characteristics for the COCs, chemical biodegradation data for the COCs, and Site-specific concentrations and source dimensions. These parameter values were consistent with those used in the 1-D modeling, presented above. Bioscreen can incorporate a source mass value ("soluble mass") for estimating the time to source depletion, assuming a source depletion rate, an internal Bioscreen parameter that is keyed to the magnitude of the source mass. The soluble mass in the source was estimated by multiplying the average soil and groundwater concentrations by the estimated affected soil and groundwater volumes. M/H estimated that 1,338 lb of ethylbenzene and 6,239 lb of xylene are present in the source areas. These estimates were incorporated into the steady-state Bioscreen model mns for mass balance calculations (see Figures 25 and 27). For chloroform, an infinite source mass was assumed in the steady-state Bioscreen mns, as this is the most conservative assumption and it is consistent with the continuing source assumption used in the 1-D model. Steady State Bioscreen Model Results Results of the calibration modeling for these constituents are shown on Figures 24 through 29 for each COC. The calibrated half-lives for the three models are as follows: • xylene 200 days; • ethylbenzene 160 days; and, • chlorofonn 200 days. The calibrated half-lives are slightly higher in the 2-D model due to the effects of fransverse dispersion on the centerline concenfrations. Based on the results of 2-D modeling, the distance at which compliance is attained for each COC is as follows: • xylene • ethylbenzene • chlorofonn 80 ft; 110 ft; and. 60 ft. Golder Associates ^ ^ -» « 400030 I p w June 2001 -26- 003-6016 Combining these results with the 1-D model results reveals that, using the most conservative estimates, compliance for xylene and ethylbenzene contamination in the AST Area is anticipated at 110 feet and 125 feet, respectively, from well MW-1. In the FPP Area, compliance for chloroform is anticipated at 60 feet from well MW-2. Plume mass analysis by Bioscreen revealed that 88%, 96%, and 97% of the chloroform, total xylenes and ethylbenzene mass, respectively, that has left the source areas has been biodegraded. The source masses of xylene and ethylbenzene are shown to degrade by 20% and 33% (whereas an infinite source of chlorofonn was assumed in the model). Thus, the model indicates that for these compounds, concenfrations at the source would still exceed MCLs at the time compliance is achieved at the distances stated above. However, the source mass estimates used in this model were likely overpredicted, as discussed below. Further, the transient Bioscreen model mns show depletion of the source mass below MCLs within the timeframes to attain full compliance over the plume lengths, as discussed below. The Bioscreen output for the steady-state results is provided in Figures 25, 27, and 29 for xylene, ethylbenzene and chloroform, respectively. Transient Bioscreen Modeling and Results Transient analyses were performed in Bioscreen to estimate the mass of COCs present at the Sites, and to predict the time to compliance along the entire length of the plume(s). Source mass estimates were obtained by matching the two sets of analytical data available for 1998 and 2000. The 1998 data was used as initial conditions and the source mass was calibrated to obtain a match with the 2000 data. Using the calibrated mass, extended simulations were mn to determine the estimated time to full compliance. At the request of USEPA, the hydraulic gradient in the AST area was reduced by 50 percent (i.e., to 0.003 ft/ft) to account for possible intermittent variations in the groundwater flow direction. The half-life of chloroform was also modified from 0.55 years to 0.25 years in order to fit the downgradient data accurately. The results of the simulations are included in Figures 30 to 35 for xylene and ethylbenzene in the AST area, and Figures 36 and 38 for chloroform in the FPP area. Three figures are presented for each COC: the first figure presents the data input; the second presents the centerline concentrations after two years (to show the 2000 data matching); and the third figure presents the centerline concenfrations after full compliance has been attained. Golder Associates 400031 I % p \ June 2001 -27- 003-6016 The times to attain full compliance over the plume lengths for each COC as predicted by the model are the following: • xylene 20 years; • ethylbenzene 21 years; and, • chloroform 2.5 years. The estimated source masses for each COC which best fit the data are the following: • xylene 528 pounds (AST Area); • ethylbenzene 95 pounds (AST Area); and, • chloroform 0.26 pounds (FPP Area). The total mass of xylene and ethylbenzene in the AST area is estimated to be 623 pounds. These source mass estimates are discussed further in the following section. The change in chloroform concenfration in MW-11 (FPP Area), noted in Section 2.3.3, is consistent with the results of transient modeling using Bioscreen. Figure 39 presents the input data for a simulation in which the initial concentration was set to 4 ppm, which is used (the measured concentration in the FPP source area in 1998) with a simulation time of 8 years. After three years, a pulse of chloroform was present at a distance of 80 feet from the source (Figure 40) and by year 8 (Figure 41), the pulse had traveled a distance of 180 feet from the source and reached a concenfration of 40 ug/1 (i.e., the distance and concenfration corresponding to MW-11). At that time, source area concentrations of chloroform in the model are essentially zero. This simulation indicates that small fransient increases in concentration can occur at selected locations such as MW-11, but this is not indicative of escalating concenfrations in the FPP Area or an expanding plume, considering such increases are anticipated to be of short duration. Source Mass Estimates The mass estimates previously made by M/H and the source mass estimates based on the transient Bioscreen modeling are in very close agreement for the FPP Area but differ in the AST Area. In relative terms, the mass estimates of ethylbenzene in the AST Area is estimated to be greater than xylene by both methods but the Bioscreen estimates are lower by an order of magnitude. The original mass analysis performed by M/H utilized conservative assumptions that are expected to result in an overprediction of the source masses for total xylenes and ethylbenzene. The soil concentration data used included seven soil borings over an estimated 112-foot by 76-foot Golder Associates 400032 I p \ .Iune2001 -28- 003-6016 impacted area for which two to three samples per boring were collected in 2-foot intervals over a depth of 20 feet in the unsaturated zone. The arithmetic mean of seven borings was used to represent the average concenfration over the entire impacted soil volume. However, the data are highly variable, ranging from 0.006 to 1,800 mg/kg of xylene, with most samples less than 200 mg/kg, and the calculation method will likely overestimate mass. For example, the concentration of xylene used at soil boring SBB-17, 1800 mg/kg, was an average of estimated results based on two sampling intervals (14-16 ft and 20-22 ft). The results had been estimated due to an exceedance of the calibration range of the instmment of the analytical laboratory. This concentration was then assumed to represent the entire depth (i.e., 20 feet) of the impacted soil. The contribution to the overall mass estimate based on this boring alone is 65% of the total mass estimate. Further, the averaging approach assumes that each boring represents one-seventh of the total area, or 1216 ft^. In the above example, due to the proximity of nearby borings, the area over which SBB-17 should more realistically be apphed is approximately 400 ft^. This adjustment would reduce the source mass attributable to SBB-17 by 67%. Similarly, the second most contaminated boring, SBB-4, exhibiting an "average" concenfration of 583 mg/kg, should more appropriately represent 500 ft^ in area. The effect of these two changes alone would reduce the M/H total mass estimate for xylene by about 60%. The approach used by M/H is therefore considered likely to overpredict the source mass of total xylenes and ethylbenzene in the AST Area. Whereas M/H's total mass estimate for ethylbenzene plus xylenes was 7580 lb, a more realistic prediction would be about 25%) of this estimate, or 1900 lb. The transient Bioscreen model indicated a source mass estimate of 708 lb of ethylbenzene plus xylenes. In order to reflect this uncertainty, subsequent calculations of cleanup time in this FS utilize a total source mass estimate of 1300 lb of total xylenes and ethylbenzene in the AST Area. Since the two approaches were in agreement for chloroform, a total source mass estimate for chloroform in the FPP Area remains assumed as 0.26 lb. Summary Strong evidence exists that natural attenuation processes are occurring in the shallow groundwater system. Major electron acceptors (dissolved oxygen, nifrate, ferric iron and sulfate) all appear to be involved in Site processes, and are coincident with the observed oxidation-reduction state. Trend analysis has shown significantly decreasing concenfrations of chlorofonn to below MCLs and steady concentrations of xylene and ethylbenzene. Mathematical modeling calibrated to the Site data indicates half-lives of the order of 100 to 200 days for these three compounds, indicative Golder Associates 400033 I l» p \ June 2001 -29- 003-6016 of a very robust natural attenuation environment. Both measured and modeled extent of the plumes indicates the plumes are currently contained and off-site migration is not expected. 2.4 Summary of Site Risks The Revised Final Human Health Risk Assessment (HHRA) (2000) considered the following current and future use scenarios and receptors: Current Use Scenario • Residential (adult and child) exposure to groundwater via off-site wells was evaluated. This pathway was deemed incomplete as no constituents of potential concem (COPCs) were identified in groundwater from off-site wells. • Trespasser (pre-adolescent and adult) exposure to COPCs in the surface soil/sediment collected from the Site and the sfream system (Gut System) was evaluated for three pathways (ingestion, dermal contact, and inhalation of particulates). Pre-adolescent children are assumed to be those between 7 and 12 years of age. Future Use Scenario • Industrial/Commercial (adult) exposures on-site to COPCs in groundwater, surface soil and sediment were evaluated for three pathways (ingestion, dermal contact, and inhalation of particulates or VOC vapors). • Constmction worker (adult) exposures on-site to COPCs in surface soil, sediment, and subsurface soil (up to 12 feet bgs) were evaluated for three pathways (ingestion, dermal contact, and inhalation of particulates). • Off-site residential (adult and child) exposures to COPCs in groundwater were evaluated for three pathways (ingestion, dermal contact, and inhalation of particulates or VOC vapors). For the purposes of the future off-site residential scenario, the Risk Assessment assumed that the on-site concenfrations could be present in an off-site well for the entire exposure duration. In reality, no COPCs were detected in the off-site wells or in the wells at the edge of the Site nor are they expected to reach these areas in the future (see Section 2.3). Therefore, the exposure assumptions used in this scenario are exfremely conservative. Summary of Health Risks The HHRA presented two risk calculations, based on Reasonable Maximum Exposure (RME) and the Central Tendency (CT) exposures. RME risks are based upon reasonable maximum Golder Associates 400034 I V p w June 2001 -30- 003-6016 exposures and, necessarily, use conservative default exposure assumptions. CT risk calculations are based upon more realistic Site-specific exposure assumptions which are more representative. CT risks were calculated only for those exposure scenarios where the calculated risks based on RME were greater than 1E-06 for carcinogens and the Hazard Index (HI) was greater than 1. Trespassers Calculated risks to an adult trespasser result from the presence of arsenic in surface soil in the Central Storm Drain area. As shown on Table 1, the carcinogenic risk from arsenic is not unacceptable and is at the lower end of the USEPA acceptable risk range (lE-06). There were no unacceptable non-carcinogenic risks to adult trespassers (Hazard Index less than 1). There are no unacceptable carcinogenic or non-carcinogenic risks to pre-adolescent trespassers. Industrial/Commercial Worker The risks to future on-site industrial or commercial workers result primarily from exposure to chloroform and arsenic*" in groundwater. The exposure scenario assumed that the on-site groundwater would be used as a potable water source for drinking and bathing. As shown by Table 1, the risks from on-site groundwater yield carcinogenic risks greater than lE-04 for both the RME and CT set of calculations. Additionally, the His for both the RME and the CT calculations exceed 1 (331 and 330, respectively), due to the concentrations of chloroform in groundwater. Exposures to surface soil and sediment do not result in unacceptable calculated carcinogenic or noti-carcinogenic risks. Construction Worker As indicated in Table 1, there are no unacceptable carcinogenic risks to future constmction workers at the Site. Non-carcinogenic risks to future on-site constmction workers are primarily based upon exposure to iron and manganese in surface soil. As shovra by Table 1, the cumulative non-carcinogenic hazard index is 1.2 for surface soil based on RME assumptions. CT calculated risks and RME risks for the Gut system soil/sediment are within acceptable ranges. Future Off-Site Residential Use Calculated risks to future residents primarily result from chloroform, iron, manganese, and arsenic in groundwater. As shown in Table 1, the risks to adult and child residents from exposure Calculated risks due to arsenic are based on data from well MW-10, which is upgradient of the Site, and may therefore not represent Site-related risks. Golder Associates 400035 I h p h June 2001 - 3 1 - 003-6016 to Site groundwater yield carcinogenic risks greater than lE-04 for the RME set of calculations, while the CT set of calculations yields risks in the 9E-05 to lE-04 ranges for adults and children, respectively. Additionally, the hazard indices for both the RME and the CT calculations exceed 1 for both the adult and child receptors due to chloroform in the groundwater. As noted previously, this exposure scenario assumed that on-site concentrations would be present off-site. This is not the case, nor can be it be anticipated in the future, and so the calculated risks (both RME and CT) are extremely conservative. Screening Ecological Risk Assessment (SERA) The Screening Ecological Risk Assessment (SERA), conducted as part of the RI, focused on the drainage channels adjacent and downstream of the Site including the River Gut, Bethlehem Gut, and Fairplains Gut. The SERA was developed using data obtained through a surface soil/sediment sampling program conducted within the three drainage channels (M/H, 2000). In general, aluminum exposure may potentially impact herbivorous, insectivorous, and piscivorous wildlife foraging in the Gut System. Aluminum and several other constituents of potential ecological concem (COPECs), identified for plants, measured adjacent to or downstream of the Site were found at similar or lower concenfrations to those measured at the upsfream reference location. This suggests that the COPECs have been transported from upgradient sources. Soil data from 1986 and 1997 at the Cenfral and Southern Storm Drains suggest that several metals (e.g., aluminum, manganese, and zinc) may have been historically discharged to downstream areas of the River Gut (M/H, 2000). The potential confribution of aluminum to the Gut System has decreased with time, as evidenced by a substantial reduction in concenfrations in 1997. The aluminum concenfrations measured in soil from storm drains in 1997 were similar to those measured in soil collected from the River Gut upstream of the drain discharge points. Therefore, it is unlikely that there is a current on-Site source of aluminum to the River Gut. The Bethlehem Gut contained the next highest concenttation of aluminum. However, a bauxite plant is located in close proximity to the Site and may serve as a source of aluminum (M/H, 2000). The concentrations of manganese and zinc were elevated in 1997 soil samples from the Storm Drains. The SERA showed that these concenfrations, if discharged to the Gut System, would results in minimal to negligible risk to ecological receptors in the drainage channels (M/H, 2000). Golder Associates 4 0 0 0 3 6 I < • p w June 2001 -32- 003-6016 3.0 REMEDIAL ACTION OBJECTIVES Based on the Conceptual Site Model and the results of the risk assessment, the following specific'' Remedial Action Objectives (RAOs) have been established: • Mitigate the toxicity, mobility and/or volume of VOCs (notably ethylbenzene and xylene) in soils in the AST area so as to minimize continued leaching to groundwater; • Mitigate the toxicity, mobility and/or volume of VOCs (notably ethylbenzene and xylene) in shallow groundwater in the AST area and downgradient so as to protect potential future groundwater users; • Mitigate the toxicity, mobility and/or volume of chloroform in shallow groundwater in the FPP area and downgradient so as to protect future potential groundwater users; • Restrict groundwater use on-site for potable purposes until the quality is restored to MCLs; and, • Restrict the use of the Site to non-residential purposes until the quality of soil and groundwater media are restored. 3.1 Preliminary Remediation Goals 3.1.1 ARARs and TBCs Section 121(d) of CERCLA requires that remedial actions at CERCLA sites comply with legally applicable or relevant and appropriate cleanup standards, standards of confrol, and other substantive environmental protection requirements, criteria or limitations promulgated under Federal or State/U.S. Territorial law, which are collectively referred to as "ARARs", unless such ARARs are waived under CERCLA § 121(d)(4). "Applicable" requirements are those cleanup standards, standards of confrol, and other substantive environmental protection requirements, criteria or limitations promulgated under Federal or State law that specifically address a hazardous substance, pollutant, contaminant, remedial action, location, or other circumstance at a CERCLA site. "Relevant and appropriate" requirements are those requirements that, while not legally "applicable", address problems or situations sufficienfly similar to those encountered at the site that their use is well suited to the particular site. Only those State/U.S. Territory standards that are promulgated, are identified by These RAOs are consistent with those previously identified in the FS Tech Memo but provide greater specificity based on the results of the Final RI Report, including the Addendum, and the Final Risk Assessment. Golder Associates 400037 I % • I June 2001 - 3 3 - 003-6016 the State/U.S. Tenitory in a timely manner, and are more sfringent than Federal requirements may be applicable or relevant and appropriate. ARARs may relate to the substances addressed by the remedial action (chemical-specific), to the location of the site (location-specific), or the manner in which the remedial action is implemented (action-specific). In addition to applicable or relevant and appropriate requirements, the lead agency may, as appropriate, identify other advisories, criteria, or guidance to be considered for a particular release. The "to be considered" (TBC) category consists of advisories, criteria, or guidance that were developed by USEPA, other federal agencies or states/territories that may be useful in developing CERCLA remedies. The following discussion identifies chemical-specific ARARs and TBCs for the Site which are then used to establish the Preliminary Remediation Goals (PRGs). Location-specific and action- specific ARARs and TBCs are discussed in Section 7 (Detailed Evaluation of Altematives). Chemical-Specific ARARs and TBCs Chemical-specific ARARs and TBCs represent health or risk-based concenfration limits in various environmental media for specific contaminants. They are used to establish cleanup criteria for remedial actions in order to protect human health and the environment. Generally, State/U.S. Territorial ARARs are used only where they are more stringent than the Federal ARAR-equivalent. As such, where equivalent Federal and State/U.S. Territorial ARARs exist, only the Federal ARARs are cited. The following chemical-specific standards are available for the media covered by the RAOs; • National Primary Drinking Water Standards (40 CFR Part 141) establishes primary maximum contaminant levels (MCLs) for public water systems measured at the tap based on protection of health and consideration of technical and economic feasibility. The MCLs provides the standards for groundwater and are applicable to the Site. USEPA Soil Screening Levels (SSLs) (EPA 1996) are unpromulgated and as such are not ARAR but are classified as "To Be Considered" (TBC). As stated in the USEPA Soil Screening Guidance: User's Guide (USEPA, July 1996) the "SSLs are not national cleanup standards. SSLs alone do not frigger the need for a response actions or define 'unacceptable' levels or contaminants in soil". Golder Associates 400038 I % # I June 2001 - 34 - 003-6016 3.1.2 Preliminary Remediation Goals Preliminary Remediation Goals (PRGs) derived from the ARARs and TBCs are provided in Table 2 for the key constituents of concem (COCs) identified in the Risk Assessment. The PRGs consist of numerical targets for the COCs in a specific media and are intended to guide the development of remedial altematives^ Based on correspondence between Berlex, P&U, M/H, and USEPA during the RI process, a Site-specific Dilution and Attenuation Factor (DAF) of 10 was developed and agreed upon by the parties. This value has been utilized for the development of the PRGs reflected in Table 2. Performance standards (as distinct from PRGs) will be established following remedy selection by USEPA. Golder Associates 400039 I % # June 2001 - 3 5 - 003-6016 4.0 DEVELOPMENT AND SCREENING OF ALTERNATIVES 4.1 General Response Actions Existing response actions at the VICHEM Site are described in the Revised Final RI Report (2000). These generally include removal of waste materials and contaminated soils. In addition, a security fence was installed around the Site in early 2000. For the purposes of the identification and screening of potential final remedial technologies, general response actions (GRAs) are developed in accordance with the remedial action objectives (see Section 3.1). GRAs are those that, singly or in combination, satisfy the RAOs for the identified media by reducing the concenfration of hazardous substances or reducing the likelihood of contact with hazardous substances. Typical GRAs include tteatment, containment, institutional confrols, excavation, extraction, disposal, or combinations of these methods. The Feasibility Study Technical Memorandum (M/H, March 1999) identified the following GRAs for the VICHEM Site: • No action; • Institutional controls; • Containment; • Removal/collection; • Treatment; and, • Disposal/discharge. These GRAs were further investigated and screened for specific technologies and process options. 4.2 Screening of Technology and Process Options FS Technical Memorandum The FS Tech Memo includes a preliminary screening of technologies and process options for groundwater and soil. I Golder Associates 400040 I % » \t June 2001 -36- 003-6016 Soil Based on the FS Tech Memo, the following remedial technologies and process options for soil were retained for further evaluation: Remedial Technology Process Option None (No Action) Not applicable Access / Use Restrictions Land use restrictions, deed/zoning restrictions, fencing Environmental Monitoring All media Surface Controls All processes Excavation All processes Structure Dismantling / Demolition All processes Biological (In-Situ) Bioventing, biodegradation Chemical / Physical (In-Situ) Soil vapor exfraction Biological (Ex-Situ) Solid phase Thermal (Ex-Situ) Incineration, thermal desorption On-site Disposal Staging, backfill freated material After further evaluation of implementability and cost, the following process options were eliminated from further consideration: bioventing, biodegradation, incineration, and thermal desorption. USEPA CERCLA guidance (USEPA, 1993) states that soil vapor exfraction (SVE), thermal desorption, and incineration are the presumptive remedies for Superfund sites with VOC- contaminated soil, provided that the site characteristics meet certain criteria. In the present case, SVE is the presumptive remedy for the VOC-contaminated soils (e.g., ethylbenzene and xylene in the AST Area) at the VICHEM Site. Although the use of a presumptive remedy typically precludes the need for identification and screening of altematives, the screening work performed in this FS has been included for completeness. EPA's presumptive remedy guidance references the BTEX compounds, among others, as those amenable to SVE. In accordance with the evaluation criteria in this guidance, the presence of VOCs has been confirmed in soil and a Site-specific SVE pilot study has been performed that indicates that SVE is feasible for the AST Area. The Spring 2000 SVE pilot study description, results, and conclusions are contained in the Draft SVE/AS Pilot Study Report (Golder, 2000), the results and conclusions of which are discussed below and in Section 5.3. Golder Associates 400041 I % p ! » June 2001 -37- 003-6016 Groundwater The FS Tech Memo identified the following remedial technologies and process options for groundwater to be retained for further evaluation: Remedial Technology Process Option None (No Action) Not Applicable Access / Use Resfriction Groundwater use restrictions, deed/zoning restrictions Altemate Water Supply All processes Monitored Natural Attenuation Groundwater monitoring Environmental Monitoring All Media Exttaction Extraction Wells Biological (In-Situ) Bioventing, chemical bioaugmentation Physical (In-Situ) Air sparging, vertical recirculation wells, air or steam sfripping Physical (Ex-Situ) Sedimentation, filfration Chemical(Ex-Situ) Carbon adsorption, precipitation/coagulation/flocculation On-site Discharge Surface water, injection wells, infiltration Off-site Discharge Publicly Owned Treatment Works (POTW) After further evaluation of implementability and cost, the following process options were eliminated from further consideration: vertical recirculation wells, steam stripping, injection wells, infiltration, and off-site discharge to POTW.' Air Sparging Evaluation The field Treatability Study conducted by M/H in Spring 2000 included the evaluation of air sparging (AS) as a potential technology to be used in conjunction with SVE to enhance the removal of VOCs in groundwater. The results of this study, plus additional groundwater sampling conducted concurrentty with the SVE/AS Treatability Study (see RI Addendum, Golder, 2000), provided the basis for additional analysis of potential groundwater remedial altematives. The results of this study are presented and discussed in detail in the Draft SVE/AS Pilot Study Report (Golder, 2000) and include vacuum/pressure responses in the vapor probes, dissolved oxygen levels in groundwater, mass removal rates of COCs, and changes in concentration of Site COCs in groundwater during testing. The SVE/AS Pilot Study Report also includes figures depicting the layout of SVE and AS wells and monitoring probes, the process schematic, and well/probe constmction details. ' In subsequent correspondence, USEPA indicated that discharge to POTW should be retained. Golder Associates 400042 I h p % June 2001 -38- 003-6016 Evidence of the effectiveness of the air sparging system in the AST Area during the pilot test includes reduction in groundwater concentrations and attainment of significant mass removal rates. A 92% reduction in total ethylbenzene and xylene concenfrations in groundwater was achieved during the SVE/AS test in the AST Area, based on data from monitoring well MW-1 (i.e., pre-test value of 130 ppm and post-test value of 10 ppm). Data collected during the pilot test indicated minimum removal rates of 8 lb/day'° for a single air sparge well. Pilot testing conducted with air sparging and SVE together showed much higher removal rates compared with SVE alone. Based on a total estimated mass of ethylbenzene and xylenes in soil and groundwater of 1300 pounds and a removal rate of 8 lb/day, remediation of the AST Area could potentially be achieved within six months. Given that removal of residual mass would be increasingly controlled by diffusion, rather than by advection, over time, the actual cleanup time would likely be somewhat greater. However, the effects of natural attenuation via biodegradation would be expected to significantly reduce the estimated cleanup time. Therefore, for the purposes of this FS evaluation, an estimated cleanup time of one year has been assumed. The total mass removal of chloroform over the three-day extended SVE/AS pilot test was estimated to be 11 grams, which is small, but is approximately 9% of the total estimated source mass of 0.26 pounds. Vapor pressures and dissolved oxygen measurements indicate that the radius of influence in the FPP Area was substantially less than the AST Area. This is likely due to the difference in subsurface soil conditions between the FPP Area and the AST Area. The borehole logs from SVE wells in the AST Area indicate that there is a more permeable, sandy layer from approximately 7-16 feet bgs, which is within the screened interval of the SVE wells. Vapor probes screened at 15 feet bgs indicated the sfrongest pressure responses. In confrast, a mostly uniform clay was indicated to a depth of 18 feet bgs in the FPP Area. As discussed further in Section 2.3, biodegradation of chloroform in the FPP Area is occurring under anaerobic conditions. The infroduction of oxygen via air sparging in the FPP Area would be counterproductive by altering the subsurface biogeochemical conditions such that natural attenuation processes may be dismpted in that Area. This rate is approximate due to uncertainty in the velocity measurements. Golder Associates 400043 I ^ li June 2001 -39- 003-6016 Therefore, based on the results of the SVE/AS Treatability Study and the natural attenuation conditions of the FPP Area subsurface, the use of air sparging as a remedial technology for groundwater in the FPP Area was eliminated on the basis of limited effectiveness, and was retained in the AST Area on the basis of cost, effectiveness, and implementability. SVE could be used for source freatment (control) of chloroform in the FPP Area; however, remaining source amounts are minimal (e.g., 0.26 lb). Groundwater Extraction and Treatment Evaluation At the request of USEPA, groundwater extraction and freatment ("pump and treat") was retained as a process for further detailed evaluation. The investigation performed by M/H in Spring 2000, which involved the replacement of former production well P-1 and Site-wide groundwater sampling, verified that neither the deep Alluvial aquifer nor the Kingshill aquifer are impacted. Therefore, the pump and tteat evaluations for both the AST and FPP Areas consider the upper Alluvium only. Further, the sampling and modeling data indicate that the shallow groundwater plumes in both Areas are not growing and have attenuated significantly. This is evidenced by the limited extent of contamination and by reductions in source concenh-ations compared to those measured in the earlier phases of the RI. The latest RI investigations also show that shallow aquifer contamination above MCLs does not extend to off-Site receptors, nor is it expected to do so in the future. Regardless, the pump and freat evaluation for both Areas was conducted in a conservative manner, using the historical RI data that indicates higher concentrations and a greater extent of impacts than recent groundwater data would suggest. FPP Area The constituent of concem in the groundwater in the FPP Area is chloroform, the historical soil and groundwater concentrations of which are provided in the RI Report (McLaren/Hart, 2000). For this evaluation, a worst-case design concentration of 1000 ppb of chloroform in groundwater was used. This value is on the order of the highest detected groundwater concentrations during 1998 in the FPP Area, but is conservative compared to the highest detected concenfrations in the most recent Spring 2000 monitoring event (i.e., 40 ppb, which is below the MCL). I Golder Associates 400044 I % p June 2001 -40- 003-6016 A pump and treat system for the FPP Area would conceptually comprise a pumping system (i.e., extraction wells with submersible pumps), an ex-situ treatment train to degrade or remove chloroform from the water, and a freated water discharge system. The number of extraction wells and their combined pumping rate was estimated to effect sufficient capture of the groundwater within the upper alluvium in the FPP Area, since only the shallow groundwater in the FPP Area has contained chloroform at concentrations in excess of MCLs. An appropriate pumping rate to achieve reasonable drawdown over the required capture zone was estimated using the following steady-state solution from Todd (1980): gin — where: h = hydraulic head at radial distance r from the pumping well [L] Ho = Initial hydraulic head [L] = saturated thickness Q = Pumping rate [LVT] ro = Radius of influence [L] = J.^ R = Precipitation recharge [L^/T] r = Radial distance [L] k = Horizontal hydraulic conductivity [L/T] The horizontal hydraulic conductivity was taken from the slug test analysis for MW-2 in conjunction with a recharge rate of 2.64 inches per year, and a saturated thickness of 15 feet based on remedial investigation data (M/H, 2000). Based on this analysis, an estimated pumping rate 0.8 gpm from each of two wells spaced approximately 100 feet apart, was selected. The primary exfraction well would be located in the source area where the highest concenfrations of chloroform in groundwater have been historically encountered. The capture zone exhibited by this well would essentially include the entire plume of impacted groundwater. The secondary extraction well would be located Golder Associates 400045 I ^ p I June 2001 - 4 1 - 003-6016 downgradient of the source area within the historical chloroform plume area, in order to capture residual chloroform contamination that has already migrated beyond the source area, and as a backup for the primary extraction well. The calculations and combined drawdown cone established by superposition, as shown on Table 3, indicate a minimum drawdown of 2 feet between the wells, and approximately 0.8 feet at a distance of 100 feet from each well. The stagnation point (i.e., the point furthest downgradient from which a particle of water will be drawn back into the well), and the width of the capture zone were estimated from the following formulae, which consider the effects of horizontal hydraulic gradient on the width of the capture zone: ITTTI where: x = Stagnation point distance [L] i = Horizontal hydraulic gradient [dim] T= Aquifer transmissivity [L^T] = KHQ and: Q y ITi where: y = half-width of the capture zone [L] These calculations confirm that these pumping rates would produce a capture zone of sufficient size (theoretically, about 285 feet in width and 46 feet to stagnation point). Several factors may affect the ultimate pumping rate of the extraction system. Aquifer heterogeneities, as seen in the variability in hydraulic conductivity, may result in slightly higher or lower pumping rates. During constmction of some Site wells, increased water yields were noted (e.g., MW-15), however the storage of any potential zones of higher transmissivity is not likely to be high, therefore the increased yields may not be sustainable. The average design exfraction rate would be refined and established in design but was assumed to be 1.6 gpm for the purpose of the FS. A worst-case pumping rate of 3 gpm was also assumed. Golder Associates 4 0 0 0 4 6 I % p % June 2001 -42- 003-6016 Three tteatment trains for the extracted groundwater were evaluated: (1) air sfripping; (2) aeration and filfration with granular activated carbon (GAC) adsorption; and, (3) ulfraviolet inadiation/oxidation (UV/ox). Air Stripping Air stripping would be accomplished with a low-profile tray air sfripper. The extracted groundwater would be pumped to a storage/equalization tank and then to the air sfripper where it would flow across multiple aeration trays. Air is blown countercurrently through small holes in the aeration frays, forming a froth of bubbles to provide a large mass fransfer surface area where the contaminants are volatilized. Because of the scouring produced by the froth, the frays are relatively resistant to fouling by iron. In addition, the frays can be cleaned with pressure-washing wands via cleanout ports at each tray level. The air stripper is expected to remove 99.9%) of the chloroform in the contaminated groundwater to achieve an effluent concenfration below 1 ppb. Based on an assumed influent concenfration of 1000 ppb (based on RI data) and a 3 gpm flow rate, the worst-case (i.e., 100% stripping efficiency) emissions of chloroform would be 0.0015 Ib/hr (0.007 tons per year) or 0.5 ppmv. This mass loading is well below the Tide V major source thresholds for hazardous air pollutants (40 CFR 51; Subpart Q 51.322) and is also less than the limits imposed by VIDPNR at other remedial sites in the Virgin Islands. Aeration and Filtration with GAC Adsorption Aeration is necessary to remove contaminants, such as iron, that may interfere with the effectiveness of the GAC in removing chloroform. Conversion of ferrous iron to the ferric state occurs rapidly upon aeration. The resulting ferric hydroxide would removed by filfration using a bag filter system. If such contaminants were to remain in the water, they would adsorb to the GAC and consume much of the available surface area for chloroform adsorption. In addition, a portion of the dissolved solids in the groundwater would deposit on the carbon, thereby increasing the pressure drop associated with the carbon unit. Thus, the effective life of the GAC would be greatly reduced, and material and operational costs would magnify. With aeration as prefreatment, these problems are reduced; however, this pretreatment step would infroduce operational and maintenance costs associated with aeration equipment (e.g., blower and diffusers or mechanical agitator), and changing and disposing of the bag filters. Golder Associates 400047 I ^ p Iune2001 - 4 3 - 003-6016 Following aeration, the water would be pumped to the GAC system. Chloroform is poorly absorbed to carbon and so requires an extended contact time compared to other organic contaminants. A GAC system comprising two 55-gallon dmms of carbon (approximately 165 pounds of carbon in each) in a lead-lag configuration has been evaluated. Each dmm would provide about 15 minutes of contact time, for a total of 30 minutes. With this contact time, the GAC is expected to remove the chloroform in the groundwater to non-detect levels. The worst-case air emissions of chloroform would be lower than for air sfripping and so off-gas confrols are not expected to be required. Based on the design assumptions and a 50% working efficiency of the carbon as compared to equilibrium conditions, the expected life of a carbon unit would be 2-3 weeks, or 18 units per year. The spent carbon would require off-site disposal or regeneration. Monitoring would also be required to evaluate breakthrough of chloroform. In addition, the spent bag filters, containing iron precipitate and sediments, would require frequent changing and disposal. Based on the relatively high operations and maintenance requirements and associated expense for this system, it has been eliminated from further consideration. Ultra Violet Irradiation/Oxidation In the ulfraviolent irradiation/oxidation (UV/OX) process, UV radiation is emitted into the contaminated water, and an oxidizing agent (such as hydrogen peroxide) is added. The UV light activates the oxidizing agent to form oxidizing species called hydroxyl radicals, which then desfroy the organic compounds in the water. In the case of chloroform destmction, a catalyst may be required. There are no air emissions from this process. The 1.6 gpm flow rate expected from the groundwater exfraction wells is not high enough to produce the turbulence needed for effective UV/ox. Thus, the groundwater would be pumped to a batch tank and then mn through the UV/ox system in intermittent batches at 15 gpm. The UV/ox system would consist of a skid mounted 30 kW system with built-in programmable logic confroller. Secondary containment and a safety shower with eyewash would be required. Wastes generated would include spent UV bulbs and empty hydrogen peroxide containers. I Golder Associates 400048 I % • I June 2001 -44- 003-6016 Capital costs for the UV/ox system are high and as this is an energy-intensive process, the operational costs are also high. These costs are anticipated to be much higher than the costs for the other technologies. For this reason, UV/ox has been eliminated from further evaluation. Three options were considered for the disposal of the treated water: (1) surface water discharge to the River Gut; (2) groundwater discharge via on-site reinfilfration pond; and, (3) discharge to a publicly-owned freatment works (POTW). Surface Water Discharge Discharge to the River Gut involves pumping the freated groundwater from the freatment plant to the River Gut that runs along the eastem and southem borders of the property. The discharge water quality will need to meet or exceed the USEPA's National Recommended Water Quality Criteria for Priority Toxic Pollutants; the level for chloroform, based on human health criteria is 5.7 |dg/L. All of the treatment train altematives discussed above are expected to achieve this criterion. This option is therefore feasible and economical. Reinfdtration Reinfiltration would be accomplished via a bermed re-infilfration pond that would be constmcted in a location with sufficient surface area. An estimate for the approximate area required for the recharge basin was established using the following formula: Ki where: A = Area of the recharge basin [L^/T]; Q = Discharge rate of exfraction system [L"'/T]; K = hydraulic conductivity [L/T]; and, i = hydraulic gradient [L/L]. The vertical hydraulic conductivity used in this estimation was assumed to be ten percent of the horizontal value derived from the slug test results for MW-2 (i.e., 1.04 x 10'^ cm/sec). To account for potential clogging of the basin, this value was reduced by twenty percent (i.e., 8.3 x Golder Associates 400049 I % p June 2001 - 4 5 - 003-6016 10"^ cm/sec). As described above, the average discharge rate of the exfraction system was estimated to be 1.6 gpm from two wells. Throughout most of the year, the depth to groundwater is between twenty and thirty feet below ground surface, and therefore infiltration would not be expected to result in excessive mounding. Consequently, the vertical hydraulic gradient was assumed to be equal to 1. Using these input parameters, a basin measuring approximately 36 feet by 36 feet would be of sufficient size to infilfrate the freated groundwater. Factors that may affect the required size of the basin are the hydraulic conductivity of the shallow alluvium in the area where the basin is constructed and the degree of clogging that the basin undergoes with time. For example, the actual hydraulic conductivity may be lower than that of the strata represented by MW-2. In light of the vicinity of the local airport, operating a surface water unit on this Site is not preferable, as the water would attract animals and fowl, which may interfere with airport operations. POTW Discharge There is one POTW on the island of St. Croix. The closest sewer manhole to the site is approximately 1/8 mile from the site, across the River Gut. Approval from the Department of Public Works would be required in order to discharge to the POTW, and prefreatment standards would likely correspond to MCLs. Since the treatment frains described above would meet the more stringent surface water quality criteria, and since the River Gut is much closer to the treatment facility than the sewer, this option was eliminated from further consideration. Cleanup Time The time required for cleanup of the chloroform impacted groundwater was estimated using the batch flush analytical model developed by USEPA (National Academy Press, 1994). This model allows the estimation of cleanup time based on the number of pore volumes required to be pumped from the contaminated groundwater in order to attain the desired cleanup goal. This approach assumes simple advective displacement of contaminated water, neglecting dispersive fransport. The other significant assumption is that the extracted pore volume is replaced with clean influent water, which instantaneously reaches equilibrium with the remaining sorbed contaminant mass. The equation to determine the number of required pore volumes is as follows: I Golder Associates 400050 I % • % June 2001 - 4 6 - 003-6016 P V = - R l n C , , , / C v . o where PV =Number of pore volumes R = Retardation factor Cvr = Cleanup concenfration Cwo = Initial contaminant concenfration For chloroform, the retardation factor used was 1.6 (see Section 2.3.4), the initial concenfration was 1000 ppb, and the cleanup concenfration was 80 ppb. This resulted in a calculated requirement of 4 pore volumes. The plume was estimated to encompass a volume of approximately 480,000 cubic feet, based on 1998 RI Data as shown in Figure 15. Based on 20% porosity and a pumping rate of 1.6 gpm, the estimated time required for cleanup based on this model would be 3.4 years. In general, this model will underestimate cleanup time, therefore, this estimate should be considered as the minimum practicable cleanup time, given the assumptions outlined above. More importantly, this model does not account for heterogeneities in soil, which are significant in the FPP Area since contaminant migration is likely to be more diffusion-confrolled than advection-controlled given the clayey nature of the Alluvium at these depths. Conversely, some conservative assumptions were built into the calculations, including the areal extent of the plume (200 feet by 120 feet) and the initial concentration of 1000 ppb, in order to develop a more realistic estimate. For the purposes of this FS, including costing, a cleanup time of 5 years has been assumed. A groundwater pump and freat system would be a relatively aggressive means of source removal; however, the implementation in the FPP Area of an aggressive method of hydraulic containment and/or source removal of chlorofonn is not warranted for the following reasons: • The Site data suggests the chloroform plume is not growing, has attenuated significanfly, and does not pose a risk to off-site receptors. • As described earlier in Section 2.0, the chloroform plume is naturally attenuating via anaerobic reductive dechlorination. The action of pumping groundwater will dismpt the anaerobic geochemical environment that currently supports natural attenuation processes, due to the influx of oxygenated water from upgradent as a result of the groundwater extraction. • The Spring 2000 data shows significant reductions in chloroform over the last two years, and only one monitoring point that slightly exceeds MCLs. Golder Associates 400051 I % p ^ June 2001 -47- 003-6016 • The influx of clean water caused by pumping will likely increase the rate of attenuation by dilution, and, as noted by USEPA, may result in the exfraction of water that - untreated - would probably meet the cleanup goals from the start. • Based on the results of the fransient Bioscreen modeling, full compliance with cleanup goals for chloroform would be achieved by natural attenuation in less time as would be required for pump and freat in the FPP Area. ASTArea At the request of USEPA, a detailed pump and freat evaluation was conducted for the AST Area in the same manner as the evaluation for the FPP Area. The constituents of concem in the AST Area groundwater are xylene and ethylbenzene. Based on the RI Report data from 1998 (McLaren/Hart, 2000), reasonable worst-case influent concenfrations of 23 ppm and 110 ppm for ethylbenzene and xylene, respectively, were assumed for this evaluation. The analysis for groundwater exfraction rates and capture zone was conducted in the same manner as described above for the FPP Area. The average horizontal hydraulic conductivity was taken from the slug test analysis for MW-6 in conjunction with a recharge rate of 2.64 inches per year and a saturated thickness of 15 feet. The results, as shown on Table 4, indicate that two extraction wells each pumping at an average rate of 3.5 gpm (5 gpm worst-case), spaced 100 feet apart, will produce a minimum 2-foot drawdown between the wells and over one foot of drawdown at a distance of 100 feet from the well. The stagnation point was calculated to be 67 feet. As discussed above, intermittent zones of higher fransmissivity may contribute to higher exfraction rates, but these higher yields are not expected to be sustainable and were therefore not factored into the design pumping rates. Based on the results of the treatment frain evaluation conducted for the FPP Area, and given the much higher concenfrations of xylene and ethylbenzene in groundwater than chloroform, as well as the chemical properties of these compounds, a freatment frain of equalization followed by air sfripping was selected. Based on a 2-fray low profile air sfripper, an air flow of 150 scfm would be required for removal of these constituents in order to meet discharge standards (assumed to be 3100 ppb for ethylbenzene based on the National Recommended Water Quality Criteria and 10,000 ppb for xylene based on the MCL). The estimated air effluent concenfration would be 212 ppmv or 0.53 pounds per hour, and off-gas confrols were assumed not to be required. Golder Associates 400052 I % p I June 2001 -48- 003-6016 Based on the same rationale as for the FPP Area, direct surface water discharge of the freated water to the nearby River Gut was selected based on feasibility, cost-effectiveness, and maintenance considerations. The time required for cleanup of impacted groundwater in the AST Area was estimated using the same analysis described for the FPP Area. A retardation factor of 5.7 was used for both ethylbenzene and xylene, and MCLs were used as the cleanup concenfrations. The estimated number of required pore volumes to be exfracted was 19.9 for ethylbenzene and 13.7 for xylene. Based on an ethylbenzene impacted plume volume of approximately 396,000 cubic feet (which effectively contains the xylene plume see Figure 14), 20% porosity, and 7 gpm pumping rate, the estimated cleanup time was 3.2 years. Again, this number likely represents a minimum practicably achievable cleanup time, due to the assumptions inherent in this approach. In addition to the heterogeneous nature of the soil, the other significant factor in the AST Area is the continuing leaching of ethylbenzene and xylene from the vadose zone into the groundwater, which is not accounted for in this model. These two factors together likely result in an underestimated cleanup time in the AST Area. For the purposes of FS, costing, a cleanup time of 5 years has been assumed. Although the minimum estimated cleanup times (i.e., 3-4 years) for both Areas are relatively short, the presence of geologic heterogeneities in both the AST and FPP Areas, as well as the presence of a significant source mass above the water table in the AST Area, could extend the estimated cleanup time by anywhere from a few years to more than 100 years and render these cleanup time predictions highly uncertain (National Academy Press, 1994). 4.3 Development of Alternatives Based on the foregoing discussion, the following altematives are retained for detailed analysis: • Altemative 1: No further action (required by the NCP); • Altemative 2: Monitored Natural Attenuation (MNA) with the institutional confrols (deed resfrictions on groundwater and property use); • Altemative 3: Source confrol via soil vapor exfraction/air sparging in the AST Area, combined with MNA and institutional controls. SVE would be retained as a contingent remedy for MNA in the FPP Area, if needed; Golder Associates 400053 I % June 2001 -49- 003-6016 • Altemative 4: SVE/AS in AST Area combined with Groundwater Exfraction and Treatment in FPP Area and institutional confrols; and, • Altemative 5: Groundwater Extraction and Treatment in AST Area combined with MNA and institutional controls. P I Golder Associates 400054 I % p ! » June 2001 -50- 003-6016 5.0 ALTERNATIVES RETAINED FOR DETAILED EVALUATION 5.1 Alternative 1: No Further Action The consideration of a No Further Action remedial altemative is required under the NCP. This option would not include the initiation of any new response actions. Under this option, the security fence installed in Spring 2000 would remain and be maintained, but the existing soil vapor exfraction / air sparging system that was installed for the Treatability Study in Spring 2000 would be rendered non-operational. 5.2 Alternative 2: Monitored Natural Attenuation (MNA) with Institutional Controls This altemative would include monitored natural attenuation (MNA) for COCs in groundwater in the AST Area and FPP Area. There is sfrong evidence to suggest that natural attenuation is effectively occurring and expected to continue at these two areas. A detailed discussion of natural attenuation indicator parameters, and evaluation of existing conditions provided in Section 2.3. A conceptual remediation plan for this altemative is depicted in Figure 42. This remedial altemative would include monitoring of shallow groundwater conditions over a period of 15 years using existing wells at the Site, plus additional monitoring wells at the AST and FPP Areas. The following parameters would be monitored: ethylbenzene and xylene isomers (AST Area only), chloroform and dichloromethane (FPP Area only), dissolved oxygen, redox potential, total organic carbon, ferrous iron, sulfate, sulfide, and methane. As shown on Figure 42, approximately three shallow groundwater monitoring wells would be added at the AST Area, and two shallow wells would be added at the FPP Area for performance monitoring of MNA. The locations of these new wells are conceptual, and final locations would be determined during design, with respect to Site topography and other physical features. Recent data through Spring 2000 indicate that the deeper Alluvium is not impacted above MCLs by any Site COCs. Therefore, vertical groundwater profiles would be obtained during drilling of select shallow wells in order to verify no impacts to the deeper zone as well as to identify appropriate screen locations. Therefore, the conceptual network of monitoring wells for performance monitoring would initially include a total of 15 new and existing shallow and deep wells (i.e., MW-1, 6, 8, 10, 18, 19, and 20 in the AST Area; and MW-2, 3, 7, 11, 12, 15, 16, and 17 in the FPP Area) at which natural attenuation parameters and concentrations of Site COCs would be monitored. This network may be refined during design and over time based on frends in the analytical data. For Golder Associates 400055 I h P % June 2001 - 5 1 - 003-6016 the purposes of this FS, the monitoring frequency is assumed to consist of quarterly sampling during the first year, semiannual sampling for the second and third years, and annual sampling thereafter of the entire network. Institutional confrols, which are implemented to reduce the potential for human exposure to constituents, would be a further component of this remedial altemative. For example, the security fence installed in 2000 would be maintained as an institutional confrol to discourage on-Site trespassers. A second institutional confrol would be continued industrial zoning use of the Site. Based on discussions with the Virgin Islands Department of Planning and Natural Resources (VIDPNR), the VICHEM Site is currenfly zoned as 1-2 (Light hidustiy). VIDPNR has indicated that the draft zoning plan for St. Croix proposes that the Site and surrounding area remain zoned as industnal (M/H, 2000). A third institutional confrol includes use and access resfrictions. Such resfrictions would include a deed notice that would mn with the land prohibiting installation of exfraction wells on-site and any residential use of the Site. The current Amended Agreement between Berlex, P&U, and CHS Holding Corporation (i.e., current property owner) states that CHS will "refrain from using the Site in any manner, or engage in any other activities that would interfere with or adversely affect the integrity or protectiveness of the remedial measures implemented or to be implemented at the Site." The Site owner also agreed to record the Amended Agreement in the St. Croix land records office, as well as to record end use deed resfrictions to resfrict future ownership or operation of the Site. Under this Agreement, the owner will also provide prior notification to Berlex and P&U of any anticipated changes in Site ownership or operation. 5.3 Alternative 3: Source Control (SVE/AS) with Monitored Natural Attenuation In addition to the institutional confrols identified in Section 5.2, this remedial altemative consists of two primary components, (1) an SVE/AS system to remediate source zone groundwater, saturated soil and vadose zone soil at the AST area and Monitored Natural Attenuation for residual groundwater contamination and (2) a Monitored Natural Attenuation (MNA) remedy for the remediation of groundwater in the FPP area and downgradient. SVE would be available for source control (freatment) in the FPP Area, if needed. A conceptual remediation plan for this altemative is depicted in Figure 43. Golder Associates 400056 I % • I Iune2001 -52- 003-6016 For the AST Area, this remedial altemative includes an air sparging system for volatilizing VOCs in shallow groundwater and saturated soil and a soil vapor exfraction system to capture sparged vapors and to volatilize and capture vadose zone soil VOC contamination. MNA would be implemented for low-level residual VOC contamination in downgradient groundwater. The SVE/AS system would freat the contaminated soil and underlying groundwater in the AST tank area as described in the Draft Final Treatability Study Workplan (M/H, 1999b). Periodic monitoring of pressure or vacuum response in SVE wells and vapor monitoring points would occur. In addition, field measurements of total organics (e.g., with a photoionization detector) and oxygen at each SVE well, as well as dissolved oxygen in groundwater, would be taken in order to balance the system and assess performance. Periodic samples of the exfracted gas would be analyzed either by an on-site mobile laboratory or off-site laboratory for individual VOC analytes. Removal rates would be estimated in the final design and during operations in order to determine compliance with the applicable air emissions standards and/or permit requirements. If emissions limits are likely to be exceeded, then appropriate off-gas confrols or operational modifications would be instituted in order to comply with applicable emissions limits. SVE/AS system design parameters will be updated based on pilot SVE/AS field tests performed in Spnng 2000 (refer to Draft SVE/AS Pilot Study Report, Golder, 2000). SVE would be accomplished using a blower equipped with a moisture separator and filter to protect the blower in conjunction with the currently installed configuration of six SVE wells. Pilot test results indicated that the SVE radius of influence (ROI) was approximately 30-40 feet. The SVE wells are located at 35-foot centers (Figure A-1). The total SVE system flow rate during pilot testing was approximately 100-150 standard cubic feet per minute (scfm). Sparging would be accomplished using an oil-free air compressor able to deliver 70 scfm at pressures of up to 200 psi. The design sparge rate would be established in the final design but is likely to be approximately 4-7 scfm per well. The design sparge (compressor) pressure would be approximately 150 psi. The final remedial design would consider the effective ROI for air sparge and SVE wells and any appropriate system upgrades. Pilot tests conducted with sparging and SVE together showed much higher removal rates compared with SVE alone. The mass removed during the pilot test demonsfrates the effectiveness ofthese technologies. Although the VOC mass is primarily in the soil phase, much of the soil contamination is located at depths greater than 20 feet (M/H, 2000), which, during the Golder Associates 400057 I \ p ! » June 2001 - 5 3 - 003-6016 pilot test, was below the water table. As the water table may be higher than 20 feet for a significant portion of the year, sparging of the groundwater would be an integral component of this remedial altemative. Cycling (on and off) of the sparge flow is known to produce higher mass removal rates than a constant sparge flow (Marley and Bruell, 1995). Cycling, which was not utilized in the pilot tests, will be considered as an enhancement during the final remedial design. Other enhancements will be considered, such as automation of the system in terms of data collection and operational confrols. For the reasons discussed in Section 4.0, AS is not considered appropriate for the FPP Area and may be counterproductive. The absence of a chloroform source in FPP vadose-zone soils does not warrant the use of SVE in this area for active removal; nevertheless, this source confrol technology is available for use in the FPP Area, if needed, in conjunction with MNA. Monitored natural attenuation to treat groundwater is therefore proposed in this remedial altemative for the FPP Area, as discussed in Section 5.2. For costing purposes, the same network and sampling scheme for groundwater monitoring as stated in Altemative 2 would be employed for an assumed 15 years. 5.4 Alternative 4: SVE/AS with Groundwater Extraction and Treatment In addition to the institutional confrols identified in Section 5.2, this remedial altemative includes two additional primary components, (1) SVE/AS to remediate source zone groundwater, saturated soil and vadose zone soil at the AST Area and Monitored Natural Attenuation for residual groundwater contamination, and (2) groundwater exfraction and treatment system for the remediation of impacted groundwater at the FPP Area. A conceptual remediation plan for this altemative is depicted in Figure 44. The SVE/AS portion of the remedy in the AST Area would be the same as described in Section 5.3. At the FPP Area, the groundwater exfraction system would be comprised conceptually of two extraction wells, located approximately 70 feet apart, each with a average design pumping rate of Golder Associates 400058 I h p ^ June 2001 - 54 - 003-6016 0.8 gpm and a worst-case pumping rate of 1.5 gpm. The wells would each be equipped with a submersible pump. The exfraction system is described further in Section 4.2. As shown on Figure 44, the primary exfraction well (EW-1) would be located in the source area where the highest concenfrations of chloroform in groundwater have been historically encountered. The capture zone exhibited by this well would essentially include the entire plume of impacted groundwater. The secondary exfraction well (EW-2) would be located downgradient of the source area within the historical chlorofonn plume area, in order to capture residual chloroform contamination that has already migrated beyond the source area, and as a backup for the primary extraction well. These locations are considered to be conceptual in nature; final locations would be determined during design, with respect to Site topography and other physical features. The freatment system would consist of an storage/equalization tank, from which groundwater would be pumped to a low profile air stripper for removal of chloroform. Treated water would be discharged via pipeline to the River Gut. System monitoring would include pre- and post-air stripper water sampling in order to evaluate removal efficiency in the air stripper and compliance with surface water discharge limits. Also, an air flow indicator would be monitored periodically to ensure sufficient air flow from the blower for mass fransfer in the sfripper. Differential pressure across the air stripper would also be monitored, in addition to periodic visual inspection of the frays, to evaluate whether fouling or other impediments to air flow have occurred. Mass emissions from the air sfripper would be calculated by using the measured concentrations of chloroform in the influent water and freated water and the flow rate from the storage tank to the stripper. The cone of depression and extent of the capture zone induced by the extraction wells would be assessed by measuring water levels at new and existing groundwater monitoring wells. For costing purposes, the same network of wells and sampling frequency described in Altemative 2 has been assumed initially. Although MNA is not an explicit component of this altemative for the FPP Area, natural attenuation parameters would be monitored periodically in the FPP Area to assess the effects of the pumping system on anaerobic biodegradation processes. However, it is expected that the network of wells to be monitored for chloroform would be reduced over time, given that Spring 2000 data suggest only a very localized area of contamination slightly exceeding the MCL. Also, the monitoring is expected to continue only through the duration of Golder Associates 400059 I % p June 2001 - 5 5 - 003-6016 the operation of the extraction system (i.e., until the attainment of cleanup goals), plus two years of post-shutdown monitoring. 5.5 Alternative 5: Groundwater Extraction and Treatment with MNA and Institutional Controls In addition to the institutional confrols identified in Section 5.2, this remedial altemative includes two additional primary components, (1) Monitored Natural Attenuation for impacted groundwater in the FPP Area, and (2) a groundwater exfraction and freatment system to capture and freat impacted groundwater at the AST Area. A conceptual remediation plan for this altemative is depicted in Figure 45. At the FPP Area, the MNA portion of the remedy would be the same as described in Section 5.2. At the AST Area, the groundwater exfraction system would consist of two exfraction wells, as depicted in Figure 45. Each well would have a design flow rate of 3.5 gpm and a worst-case flow rate of 5 gpm. The two wells (EW-3 and EW-4) are located within the zone of highest xylene and ethylbenzene impacts. The expected combined capture zones of these wells would encompass the entire AST Area and extent of the xylene and ethylbenzene plumes (both on-Site and off-Site). The freatment system would be comprised of the same components and be subject to the same monitoring scheme as described in Section 5.4. Treated water would be discharged to the River Gut at a location northeast of the AST Area. For costing purposes, the network of monitoring wells and sampling frequencies has been assumed to be the same as identified in Altemative 2. The duration of monitoring in the FPP Area would be 15 years, and in the AST Area would be 7 years (i.e., five years during extraction system operation and two years of post-shutdown monitoring). I Golder Associates 400060 I P W June 2001 -56- 003-6016 6.0 NCP EVALUATION CRITERIA The selection of a remedial altemative is based on an evaluation of nine criteria established in the NCP. Two criteria (state acceptance and community acceptance) will not be evaluated in this report because they will be evaluated during the public comment period. The remaining seven criteria are listed below. Threshold criteria are those which miast be met in order for a remedy to be eligible for selection. The two threshold criteria are described below. • Overall Protection of Human Health and the Environment Under this criterion, an altemative should be assessed to determine whether it can adequately protect human health and the environment, in both the short-term and long- term, from unacceptable risks posed by hazardous substances, pollutants or contaminants present at the site, by eliminating, reducing or confrolling exposures to levels established during development of remediation goals. This criterion is an overall assessment of protection based on a composite of factors assessed under other evaluation criteria, especially long-term effectiveness and permanence, short-term effectiveness, and compliance with ARARs. • Compliance with ARARs This criterion evaluates whether and how the altemative attains applicable or relevant and appropriate requirements under federal environmental laws and state environmental or facility siting laws, or provides grounds for invoking the legal waiver of such requirements. Primary Balancing criteria are used to weigh the altematives in order to determine the best selection for the Site. The 5 balancing criteria are described below. • Short-Term Effectiveness This criterion evaluates the impacts of the altemative during implementation with respect to human health and the environment. The short-term impacts of an altemative shall be assessed considering: short-term risks that might be posed to the community during implementation of an altemative; potential impacts on workers during remedial action and the effectiveness and reliability of protective measures; potential environmental impacts of the remedial action and the effectiveness and reliability of mitigative measures during implementation. Golder Associates 400061 I p w June 2001 -57- 003-6016 • Reduction of Toxicity, Mobility, and Volume Through Treatment Under this criterion, the degree to which an altemative employs recycling or freatment that reduces toxicity, mobility, or volume shall be assessed, including how freatment is used to address the principal threats posed at the site. Factors that shall be considered include: the freatment or recycling processes; the altematives employed and the materials they will freat; the amount of hazardous substances, pollutants or contaminants that will be desfroyed, freated, or recycled; the degree of expected reduction in toxicity, mobility or volume of the waste due to freatment or recycling and the specification of which reduction(s) are occurring; the degree to which the freatment is irreversible; the type and quantity of residuals that will remain following treatment considering the persistence, toxicity, mobility, and propensity to bio-accumulate of such hazardous substances and their constituents; and the degree to which freatment reduces the inherent hazards posed by principal threats at the site. • Long-Term Effectiveness and Permanence Under this criterion, an altemative shall be assessed for the long-term effectiveness and permanence it affords, along with the degree of uncertainty that the altemative will prove successful. Factors that shall be considered, as appropriate, include: the magnitude of residual risk remaining from unfreated waste or freatment residuals remaining at the conclusion of the remedial activities; and the adequacy and reliability of confrols such as containment systems and institutional confrols that are necessary to manage freatment residuals and unfreated waste. • Implementability This criterion addresses the technical and administrative feasibility of implementing the altemative as well as the availability of various services and materials required. • Cost Cost items evaluated include capital and operation and maintenance expenditures to implement the altemative, presented as a present worth analysis. Golder Associates 400062 I p w June 2001 -58- 003-6016 7.0 DETAILED EVALUATION OF ALTERNATIVES 7.1 Alternative!: No Action Overall Protection of Human Health and the Environment The No Action remedy would be adequately protective of human health and the environment under current conditions because there are no unacceptable risks posed by the Site. However, under future exposure scenarios, a No Action remedy provides no reduction in potential risk to human health posed by hypothetical future exposure of on-site workers to COCs in groundwater. Natural attenuation processes would continue to remediate groundwater but this would not be verifiable given the absence of environmental monitoring. Compliance with ARARs The No Action option relies upon natural attenuation for attainment of groundwater ARARs. Given adequate time, this option is expected to meet these standards. There are no ARARs for soil and so compliance is not an issue for this medium. Short-Term Effectiveness No additional short-term risks to the community, workers, or the environment are posed by implementation of this option. Natural attenuation processes will require a period of years to be fully effective. Long-Term Effectiveness and Permanence Natural attenuation of groundwater constituents is an effective long-term measure that utilizes permanent treatment. Migration to groundwater of contaminants in subsurface soils within the AST Area would be a long-term concem. Because Site contaminants would be left in place, a five-year review would be required to assess the continued effectiveness of this option. Reduction of Toxicity, Mobility, and Volume Through Treatment Natural attenuation processes, under favorable conditions, act without human intervention to reduce the mass, toxicity, mobility, volume, or concenfration of contaminants in soil or groundwater. These processes include biodegradation, dispersion, dilution, sorption, volatilization chemical or biological stabilization and fransformation, among others (USEPA Golder Associates 400063 • w p w June 2001 -59- 003-6016 1999). Ongoing natural attenuation processes at the Site, in particular biodegradation, will effectively freat and reduce the volume, toxicity, and mobility of chloroform, ethylbenzene and xylene in groundwater. Some degradation by-products, such as dichloromethane, do exhibit similar toxicity; however, the expected half-lives of these by-products are short and are not present on-Site at concenfrations above MCLs. The progress of natural attenuation would not be verifiable under this altemative, given the absence of environmental monitoring. Also, mobility of subsurface soil contaminants in the AST Area into groundwater would not be addressed. Implementability The No Action option is straightforward to implement. Cost A cost estimate for this remedial altemative is showTi in Table 5. The only costs associated with this remedy would be those associated with the Site security fence. The total present worth cost for this altemative is $57,000, based upon 30 years of maintenance. 7.2 Alternative 2: MNA with Institutional Controls Overall Protection of Human Health and the Environment The MNA with Institutional Confrols remedial altemative will provide short-term and long-term protection of human health and the environment. The mass of VOCs in groundwater in the AST and FPP Areas would be permanently reduced over time by natural physical and biological processes that have been shown to be occurring. Evaluation of the historical groundwater concenfrations and natural attenuation geochemical parameters measured at the Site reveal that conditions are favorable for the anaerobic degradation of chloroform in the FPP Area, and that degradation of ethylbenzene and xylene will also proceed anaerobically in the AST Area. Institutional confrols will provide the necessary protection while natural attenuation processes effectively freat and mitigate VOCs in groundwater. Continued monitoring of reduction in groundwater concentrations and of natural attenuation indicator parameters at both the AST and FPP Areas would provide assurance and verification of the protectiveness of this remedial altemative. Golder Associates ^ ««,>.. , 400064 I p w June 2001 -60- 003-6016 Compliance with ARARs MNA is expected to achieve compliance with chemical-specific groundwater ARARs over time. Action-Specific ARARs On-site actions (i.e., within the areal extent of contamination and all suitable areas in very close proximity to the contamination necessary for implementation of the response action) need comply only with the substantive aspects of ARARs, not with the corresponding adminisfrative requirements (e.g., consultation, issuance of permits, documentation, record keeping and enforcement). Actions for this remedial altemative will include: installation, sampling, and potential decommissioning of wells, and generation of contaminated media waste. Potential action-specific ARARs, therefore, include: • Virgin Islands Well Driller Requirements (VIC, Title 12, 157) requires well drillers to obtain a license and for all non-private wells to be drilled by a licensed driller. Permits are also required for new wells. • Virgin Islands Requirements for Sealing Wells (VIC, Title 12, 161) requires effective sealing of well if highly mineralized water is encountered or well is abandoned. • Virgin Islands Solid and Hazardous Waste Management Act (VIC, Title 19, Part IV, Chapter 58) provides for the establishment of regulations for the storage, collection, transportation, and disposal of solid and hazardous waste (e.g., drill cuttings). • Department of Transportation Rules for the Transportation of Hazardous Materials (49 CFR Parts 107, 171.1 through 171.500) specify the procedures for packing, labeling manifesting, and fransporting hazardous materials from point of generation to the point of freatment, storage or disposal. • Occupational Safety and Health Standards for Hazardous Response Contractors (29 CFR 1926) establish worker health and safety program goals for CERCLA cleanup projects. Location-Specific ARARs Location-specific ARARs set resfrictions on the conduct of remedial activities in particular locations (e.g., floodplains). Generally, State/U.S. Territorial ARARs are used only where they are more sfringent than the federal ARAR-equivalent. As such, where equivalent Federal and State/U.S. Territorial ARARs exist, only the Federal ARARs are cited. Potential location-specific ARARs therefore include: • Executive Orders on Floodplain Management and Wetlands Protection (CERCLA Floodplain and Weflands Assessments-EO 11988 and 11990) require federal agencies to assess potential effects of remediation on surrounding weflands and in the floodplain. Weflands have been identified within the River Gut Channel adjacent to the Site, and are Golder Associates 400065 I p w June 2001 - 61 - 003-6016 classified as a "PF03A" wefland (M/H, 2000). This remedial altemative is not expected to impact wetlands. In the event that wetlands were to be impacted by the implementation of this remedial altemative, a wetlands assessment would be conducted in accordance with EPA's 1985 "Statement of Policy on Floodplains/Wetlands Assessments for CERCLA Actions, which includes: Weflands delineation; Discussion of the respective impacts of the remedial altemative; Characterization of existing flora and fauna; Discussion of the effects of contaminants on wetlands resources; Measures to minimize potential adverse impacts that cannot be avoided; A mitigation plan, if necessary; and. Post-mitigation monitoring plan. Since the Site lies within the 100-year floodplain of the River Gut, a floodplain assessment would need to be conducted, if constmction were to occur in the floodplain, to minimize or avoid the adverse effects of the 100 and 500-year flooding event. The assessment would include a discussion of the effects of the remedial altemative on the floodplain, a comparison to the effects of the non-selected altematives on the floodplain, possible measures to minimize potential adverse floodplain impacts, and measures undertaken to prevent spreading of Site contamination by a flooding event during implementation of this remedial altemative. Coastal Zone Management Act (16 USC 1451, 15 CFR 298, 40 CFR 6.302(d) requires approval that the remedial action be consistent with the policies of the Virgin Island Coastal Zone Management Plan (CZMP) for actions affecting the coastal zone, including lands thereunder and adjacent shorelands. The Site falls outside the designated coastal zone and so actions must only comply with the general goals of the CZMP. Archaeological National Historic Preservation Act (16 USC 469; 40 CFR 6.301(c)) requires actions to recover and preserve artifacts if alteration of tenain threatens significant scientific, prehistorical, historical, or archeological data. EPA has determined that the majority of the site area has already been disturbed. Any actions that occur in undisturbed areas could require a Cultural Resource Survey, however, this is not expected as a part of this altemative. Earth Change plans and permits (VIC Tide 12, Chapter 13, Sections 533 and 534) requires approval of an earth change plan and issuance of and earth change permit for clearing, grading, filling, or otherwise disturbing real property for any purpose. As noted above, compliance with the substantive requirements only is required. Design and implementation of this alternative is expected to comply with ARARs. Short-Term Effectiveness MNA will require a period of years to become fully effective. No additional short-term risks are posed to the community, workers or the environment by implementation of this altemative. Golder Associates 400066 I p b June 2001 -62- 003-6016 Appropriate measures would be taken to protect on-site personnel during constmction of monitoring wells and groundwater sampling activities. The use of the existing Site security fence as part of the institutional confrols provide short-term effectiveness to discourage frespassers from accessing the Site. Long-Term Effectiveness and Permanence This remedial altemative will provide long-term permanent protection of human health and the environment by permanently treating the mass of VOC contaminants in groundwater at the AST and FPP Areas, which will restore the groundwater conditions to acceptable levels. In addition, long-term monitoring would be an integral part of the MNA remedial altemative to ensure the continued effectiveness of the remedy. PRGs for soil in the AST Area would not be attained for a number of years. The Institutional Confrols described in Section 5.0 are expected to be effective in the long-term to prevent unauthorized access to the Site and future use of the Site for other than indusfrial purposes. Reduction of Toxicity, Mobility, and Volume Through Treatment The natural biochemical and physical freatment associated with the ongoing natural attenuation processes at the Site will permanently reduce the toxicity, mobility, and volume of Site contaminants in groundwater and satisfies the statutory preference for treatment. Currently, the low groundwater velocity combined with natural attenuation has effectively imposed a steady state condition of the contamination such that the plumes in both Areas are not expanding in areal extent or depth. Intermediate degradation products of natural attenuation have very short half- lives and are not expected to confribute to future exposure risks. Modeling of the AST Area indicates that 99% and 97% of the ethylbenzene and total xylenes, respectively, that have left the source areas have already biodegraded. Modeling of the chloroform plume in the FPP Area indicates that 88% of the chloroform mass that has left the source area has been biodegraded. Implementability The MNA remedial altemative is easily implementable, since it relies on natural biochemical processes that are already existing and that do not require enhancement. The services and materials required to implement this altemative are standard within the industry and readily available. Golder Associates A r^ r. ^ , 400067 I p w June 2001 - 6 3 - 003-6016 Cost A preliminary cost estimate for the MNA remedial altemative is presented in Table 6. The estimated capital costs and O&M costs for this altemative are $161,560 and $545,530, respectively. The total estimated present worth cost is $707,000. The MNA aspect of this cost includes the installation/replacement of monitoring wells and annual monitoring for 15 years. 7.3 Alternative 3: Source Control (SVE/AS) with MNA Overall Protection of Human Health and the Environment The Source Control (SVE/AS) with MNA remedial altemative will provide short-term and long- term protection of human health and the environment. Active in-situ treatment of the groundwater and subsurface soil in the AST Area will rapidly and permanently reduce the mass of VOCs in the saturated/unsaturated soil and groundwater. This action will also increase the effectiveness of aerobic biodegradation processes in the area of SVE and air sparging. Aerobic and anaerobic natural attenuation processes for groundwater VOC contamination beyond the influence of the SVE/AS system will address residual groundwater contamination, considering that ethylbenzene and xylene readily biodegrade. SVE will effectively freat the source to prevent any potential further groundwater contamination caused by migration of soil contaminants to groundwater. In the FPP Area, this remedial altemative would adequately protect human health and the environment by the reduction of the mass of chlorofonn by natural physical and biological processes that have been documented at the Site. Drastic decreases in maximum concenfrations within the FPP Area over the past two years indicate that sfrong natural attenuation processes are at work. Evaluation of the historical natural attenuation geochemical parameters measured at the Site confirms that conditions are favorable for the anaerobic degradation of chloroform. Continued monitoring of reduction in groundwater concentrations and of natural attenuation indicator parameters at both the AST and FPP Areas would provide assurance and verification of the protectiveness of this remedial altemative. SVE would also be available as a contingency measure if further source confrol were needed should MNA performance monitoring data indicate a residual source concenfration that was not protective of groundwater. Golder Associates 400068 I p V June 2001 -64- 003-6016 Compliance with ARARs The SVE/AS and MNA altemative is expected to achieve compliance with chemical-specific ARARs for groundwater. Action-Specific ARARs In addition to the action-specific ARARs identified for the MNA altemative above, the following potential action-specific ARARs apply for the SVE/AS aspects of this altemative: • Virgin Islands Air Pollution Confrol (VIC, Title 12, Chapter 9, Section 206-20) requires permitting of confrolled air discharges to atmosphere. During remedial activities at the Site, emissions must be confrolled and treated, if necessary, to comply with these standards. • Clean Air Act National Emissions Standards for Hazardous Air Pollutants (NESHAPS, 40 CFR Pt 61) establishes emissions standards for various hazardous contaminants. Soil vapor exfraction and groundwater air sparging will involve air emissions of Hazardous Air Pollutants (xylenes, ethylbenzene) and the resulting discharges must meet these emission standards. • Control of Air Emissions from Superfund Air Sfrippers at Superfund Groundwater Sites (OSWER Directive 9355.0-28) establishes guidance confrol of air emissions from air strippers used at Superfund Sites for groundwater freatment and established procedures for implementation. Although this guidance applies to air sfrippers, USEPA recognizes the potential for applicability to other VOC sources in this document. Generally, the guidelines described for air sfrippers are suitable for VOC air emissions from other vented exfraction techniques such as soil vapor exfraction. This directive is unpromulgated and as such is not ARAR but as "To Be Considered" (TBC) requirement. Location-Specific ARARs Location-specific ARARs are the same as for the MNA Altemative discussed above. Design and implementation of this Altemative is expected to comply with ARARs. Short-Term Effectiveness Consfruction activities associated with the Source Confrol with MNA altemative infroduce limited short-term risks but the remedy itself will be effective in a relatively short time-frame, as demonstrated by the Pilot Study Results (Golder, 2000). Appropriate health and safety measures would be taken to protect workers during constmction of the SVE/AS system, and subsequent monitoring. A major portion of the SVE/AS system has been consfructed already for the Spring 2000 Treatability Study. Golder Associates . „ ^ 400069 I p l» June 2001 - 6 5 - 003-6016 The existing security fence provides short-term protectiveness and discourages frespassers from accessing the Site. Long-Term Effectiveness and Permanence The Source Control with MNA remedial altemative provides long-term permanent protection of human health and the environment by permanently reducing the mass of VOC contaminants in the subsurface soils and groundwater in the AST Area, which will enhance the effectiveness of the natural attenuation remedy for groundwater and restore the soil and groundwater conditions to acceptable levels. Chloroform contamination in groundwater at the FPP Area will continue to undergo natural attenuation. The degradation processes involved in natural attenuation in both Areas will permanently reduce levels of the Site COCs. Operation, inspection, monitoring, and maintenance will be regularly conducted to ensure the continued long-term effectiveness of the SVE/AS and MNA aspects of the remedy. Reduction of Toxicity, Mobility, and Volume Through Treatment The soil vapor extraction (SVE) and groundwater air sparging will rapidly reduce the toxicity, mobility and volume of VOC contaminants in the subsurface soils and groundwater in the AST area. For example, the Spring 2000 Treatability Study showed a 92% reduction in groundwater concenfrations of ethylbenzene and xylenes in an AST Area shallow monitoring well following short-term air sparging. Natural attenuation of residual contamination in the groundwater, will also reduce the toxicity, mobility, and volume of remaining low-level VOCs in the groundwater. Chloroform contamination in groundwater at the FPP Area will continue to undergo natural attenuation reducing its toxicity, mobility, and volume. Cunently, the low groundwater velocity combined with natural attenuation has effectively imposed a steady state condition of the contamination such that the plumes in both Areas are not expanding in areal extent or depth. Intermediate degradation products of natural attenuation have short half-lives and are not expected to confribute to future exposure risks. Implementability Implementation of the Source Confrol with MNA remedial altemative utilizes established practices and the services and materials needed are standard within the industry and readily available. Moreover, these process technologies have been implemented successfully at the Site. Golder Associates 400070 I p ^ June 2001 -66- 003-6016 The basic infrastmcture and most of the equipment needed to perform this remedial altemative was installed during the Treatability Study, although some system upgrades are envisioned. Other than a slightly lengthened implementation schedule due to the remote location of the Site, no technical or adminisfrative problems are envisioned which would adversely affect the constmction or schedule for implementation of this altemative. Similarly, long-term operation and maintenance requirements can be readily performed, although the availability of personnel, equipment, and spare parts is exfremely limited on the Island. Cost A preliminary cost estimate for the Source Control with MNA remedial altemative is presented in Table 7. The estimated capital costs and O&M costs for this altemative are $850,760 and $565,860, respectively. The total estimated present worth cost is $1,417,000. The SVE/AS aspect of the cost includes the installation of additional wells, one year of SVE/AS operation, and three years of groundwater monitoring in the AST Area (i.e., quarterly during Year 1 and semiannually during Years 2 and 3). The MNA component includes 15 years of groundwater monitoring in the FPP Area with the same frequency as the AST Area for Years 1 -3 and annually thereafter. 7.4 Alternative 4: SVE/AS With Groundwater Extraction and Treatment Overall Protection of Human Health and the Environment This remedial altemative will provide short-term and long-term protection of human health and the environment. Active freatment of the groundwater in both the AST and FPP Areas will permanently reduce the mass of VOCs in the saturated zone. Further, active freatment of soil by SVE in the AST Area will also rapidly and permanently reduce the mass of VOCs in the unsaturated zone. Natural attenuation processes for groundwater VOC contamination beyond the influence of the SVE/AS system will address residual groundwater contamination. SVE will effectively prevent any potential further groundwater contamination caused by migration of soil contaminants to groundwater. Continued monitoring of reductions in groundwater concenfrations in both Areas would provide assurance and verification of the protectiveness of this remedial altemative. Golder Associates 4 0 0 0 7 1 I p w June 2001 -67- 003-6016 Compliance with ARARs The Groundwater Extraction and Treatment with SVE/AS altemative is expected to achieve compliance with chemical-specific ARARs for groundwater. Action-Specific ARARs The action-specific ARARs include those listed above in Section 7.2 for MNA, Section 7.3 for the SVE/AS aspects of this altemative as well as the following: • Federal and Virgin Islands requirements for National Pollution Discharge Elimination System (NPDES) discharges to surface water Location-Specific ARARs The location-specific ARARs are the same as for the MNA altemative described in Section 7.2 above. Design and implementation of this Altemative is expected to comply with ARARs. Short-Term Effectiveness Consfruction activities associated with this altemative infroduce limited short-term risks, but the remedy itself will be effective in a relatively short time frame. Appropriate health and safety measures would be taken to protect workers during consfruction of the SVE/AS system, consfruction of the exfraction and treatment system, and subsequent monitoring. A major portion of the SVE/AS system has been constmcted already for the Spring 2000 Treatability Study. The groundwater extraction system would conceptually involve two additional exfraction wells, and the installation of the equipment required for the freatment system units and appurtenances (tank, air sfripper, blower, pumps, housing) is straightforward, but would require labor and materials from the mainland. The existing security fence provides short-term protectiveness and discourages frespassers from accessing the Site. Long-Term Effectiveness and Permanence This altemative provides long-term permanent protection of human health and the environment by permanently reducing the mass of VOC contaminants in the subsurface soils and groundwater in the AST Area, which will restore the soil and groundwater conditions to acceptable levels. Golder Associates 400072 I P W June 2001 -68- 003-6016 Permanent reductions in the mass of chloroform will also be permanently achieved in the long- term at the FPP Area via groundwater exfraction, although these reductions are not expected to exceed the magnitude or rate that will be attained by natural attenuation alone in the absence of groundwater exfraction. Operation, inspection, monitoring, and maintenance will be regularly conducted to ensure the continued long-term effectiveness of the SVE/AS and groundwater exfraction/treatment aspects of the remedy. Reduction of Toxicity, Mobility, and Volume Through Treatment The SVE and AS will rapidly reduce the toxicity, mobility, and volume of VOC contaminants in the subsurface soils and groundwater in the AST Area, as evidenced by the Spring 2000 Treatability Study results. Natural attenuation processes, including biodegradation, of residual groundwater contamination will also reduce the toxicity, mobility and volume of any remaining low-level VOCs in the groundwater. The groundwater exfraction and freatment system will also reduce the toxicity, mobility, and volume of chloroform in groundwater at the FPP Area due to mass removal via exfraction wells. However, Spring 2000 monitoring data indicate that minimal mass remains, with groundwater concenfrations below or near MCLs. Therefore, any reductions in toxicity and volume via pump and freat in the FPP Area would be minimal. Ongoing anaerobic biodegradation processes that are currently responsible for the natural attenuation of chloroform in the FPP Area are expected to diminish due to the introduction of oxygenated water associated with the pumping action. This net effect is likely to be no additional reduction of toxicity, mobility, and volume beyond that which will occur due to natural biodegradation alone in the absence of groundwater exfraction. Implementability Implementation of this remedial altemative utilizes established practices and the services and materials needed are standard within the industry and readily available. In the case of SVE/AS, these technologies have been implemented successfully at the Site. The basic stmcture of this system was installed during the Treatability Study, and minor upgrades are envisioned. For the groundwater extraction and freatment system, a lengthened implementation schedule would be expected due to the remote location of the Site. Also, certain units such as the Golder Associates 400073 I p w June 2001 -69- 003-6016 equalization tank and air sfripper system would likely need to be manufactured and shipped from the U.S. mainland, which may extend the implementation schedule. However, no technical or adminisfrative problems are envisioned which would adversely affect the constmction of this altemative. For both groundwater exfraction/freatment and SVE/AS, long-term operation and maintenance requirements can be readily performed, although the availability of personnel, equipment, and spare parts is exfremely limited on the Island. Cost A preliminary cost estimate for this remedial altemative is presented in Table 8. The estimated capital costs and O&M costs for this altemative are $1,219,240 and $877,330, respectively. The total estimated present worth cost is $2,097,000 based on one year of SVE/AS operation and five years of groundwater exfraction and freatment. Cost include the installation of additional wells and MNA groundwater monitoring in the FPP Area for 15 years according to the following schedule: quarterly for Year 1, semiannually for Years 2 and 3, annually from Years 3 to 15; costs for groundwater monitoring in the AST Area for three years are included (i.e., one year of SVE/AS operation and two years of post-shutdown monitoring). 7.5 Alternative 5: Groundwater Extraction and Treatment with MNA Overall Protection of Human Health and the Environment The Groundwater Extraction and Treatment with MNA remedial altemative will provide short- term and long-term protection of human health and the environment. Active freatment of the groundwater in the AST Area will permanently reduce the mass of VOCs in the saturated zone. The remaining source mass in the AST Area vadose zone would be subject to anaerobic biodegradation processes, and a portion of this source mass would leach to groundwater for ultimate capture and removal by the active groundwater exfraction and treatment system. In the FPP Area, this remedial altemative would adequately protect human health and the environment by the reduction of the mass of chloroform by natural physical and biological processes that have been documented at the Site, as discussed in Sections 2 and 7.3 above. Continued monitoring of reductions in groundwater concenfrations in both Areas, and natural attenuation parameters in the FPP Area, would provide assurance and verification of the protectiveness of this remedial altemative. Golder Associates 400074 I h P V June 2001 -70- 003-6016 Compliance with ARARs The Groundwater Exfraction and Treatment with MNA altemative is expected to achieve compliance with chemical-specific ARARs for groundwater. Action-Specific ARARs The action-specific ARARs include those listed above in Section 7.4 above. Location-Specific ARARs The location-specific ARARs are the same as described in Section 7.2 above. Design and implementation of this Altemative is expected to comply with ARARs. Short-Term Effectiveness Consfruction activities associated with the Groundwater Exfraction and Treatment with MNA Altemative infroduce limited short-term risks, but the remedy itself will likely be effective in a relatively short time frame. Appropriate health and safety measures would be taken to protect workers during constmction of the groundwater exfraction and treatment system, and subsequent monitoring. The exfraction system would only involve two additional extraction wells, and the installation of the equipment required for the freatment system units and appurtenances (tank, air stripper, blower, pumps, housing) is sfraightforward, but would require labor and materials from the U.S. mainland. The existing security fence provides short-term protectiveness and discourages frespassers from accessing the Site. Long-Term Effectiveness and Permanence The Groundwater Extraction and Treatment with MNA altemative provides long-term permanent protection of human health and the environment by permanently reducing the mass of VOC contaminants in the groundwater in the AST Area. Preliminary remedial goals for soils in the AST Area would not be attained for many years and migration to groundwater would continue. Also, the long-term effectiveness of pump and freat is uncertain, considering the heterogeneous nature of subsurface strata on-Site. Chloroform contamination in groundwater in the FPP Area will continue to undergo natural attenuation, which will permanently reduce levels of chloroform over a short time period. Golder Associates 4 n n n "7 c I P W June 2001 - 7 1 - 003-6016 Operation, inspection, monitoring, and maintenance would be regularly conducted to optimize the long-term effectiveness of the groundwater extraction/treatment aspects of the remedy. Continued monitoring of groundwater concenfrations of chloroform and natural attenuation parameters in the FPP Area will be regularly conducted to ensure the continued long-term effectiveness of the MNA aspect of the remedy. Reduction of Toxicity, Mobility, and Volume Through Treatment The groundwater exfraction/treatment will reduce the toxicity, mobility, and volume of VOC contaminants in the groundwater in the AST Area. Natural attenuation processes, including biodegradation, of residual soil contamination will also reduce the toxicity, mobility and volume of remaining VOCs in the vadose zone. Spring 2000 groundwater monitoring results indicate that the remaining plume mass of chloroform is minimal with concenfrations generally below MCLs. Therefore, any reduction in toxicity and volume by pump and freat in the FPP Area would be minimal. Similarly, chloroform contamination in the FPP Area groundwater will continue to undergo rapid natural attenuation reducing its toxicity, mobility, and volume. Implementability Implementation of the Groundwater Extraction and Treatment with MNA remedial altemative utilizes established practices and the services and materials needed are standard within the industry and readily available. For the groundwater exfraction and treatment system, a lengthened implementation schedule would be expected due to the remote location of the Site. Also, certain units such as the equalization tank and air sfripper system would likely need to be manufactured and shipped from the U.S. mainland, which may extend the implementation schedule. However, no technical or adminisfrative problems are envisioned which would adversely affect the consfruction of this altemative. For both groundwater exfraction/treatment and MNA, long-term operation and maintenance requirements can be readily performed, although the availability of personnel, equipment, and spare parts is exfremely limited on the Island. Cost A preliminary cost estimate for the Groundwater Extraction and Treatment with MNA remedial altemative is presented in Table 9. The estimated capital costs and O&M costs for this altemative are $1,121,480 and $1,030,370, respectively. The total estimated present worth cost is Golder Associates 4 0 0 0 7 ^ I P W June 2001 -72- 003-6016 $2,152,000. The MNA aspect of the cost includes the installation of additional wells and groundwater monitoring for 15 years according to the following schedule: quarterly for Year 1, semiannually for Years 2 and 3, annually from Years 3 to 15. The groundwater extraction and treatment aspect of the cost includes the installation of two extraction wells, materials and installation of the freatment and discharge system, groundwater monitoring at the same frequency as described above, and 5 years of operation. 7.6 Comparative Evaluation Overall Protection of Human Health and the Environment Under the current use scenario, all five altematives provide a similar degree of protection of human health and the environment. However, the No Action altemative does not address risks to future on-site workers, and the lack of any institutional control other than the security fence would potentially allow unresfricted future use of the Site. The remaining altematives all include a monitoring component that would provide a means to evaluate the protectiveness of the remedy. Although natural attenuation would still occur under the No Action altemative, there would be no verification or measure of the extent to which these processes are occurring. Altemative 3 would be more efficient than MNA alone (e.g., Altematives 2) in overall protection of human health, since the inclusion of SVE/AS would remove mass from the AST source area more quickly, and reduce the amount of time to achieve remedial goals. Similarly, Altemative 3 would be more efficient than Altemative 5 in three ways: (1) SVE will rapidly remove and reduce the source mass in the vadose zone whereas groundwater extraction does not address the vadose zone; (2) AS is expected to be much more effective at removing mass than groundwater extraction, and will better facilitate aerobic biodegradation processes via infroduction of air; and (3) SVE/AS could be more readily implemented considering operational system costs. Each of the five altematives is expected to fully protect human health and the environment. With respect to Altemative 4, and as noted previously, cleanup in the FPP Area is expected to occur no more rapidly than via natural attenuation by itself (included as a component in Altematives 1, 2 3 and 5). Further, groundwater data from Spring 2000 show that only one monitoring well cunenfly exhibits chloroform concentrations above MCLs, which indicates that Golder Associates 400077 I p V June 2001 - 7 3 - 003-6016 natural attenuation is adequately protective without the need for any active exfraction system. As noted by USEPA, the Spring 2000 data indicates that exfracted groundwater may potentially meet discharge standards, as extracted, with no freatment. Therefore, implementing an active extraction system (i.e., Altemative 4) will not likely be any more effective or more protective than allowing natural attenuation to continue to remediate the low residual mass of chloroform in the FPP Area. Compliance with ARARs Although the No Action altemative is expected to eventually comply with chemical-specific ARARs for groundwater, there would be no monitoring component to verify attainment. All five altematives can be implemented to achieve compliance with chemical-specific, action-specific, and location-specific ARARs. Short-Term Effectiveness All five altematives are effective in the short-term. Altematives 3, 5, and 4, in this order, provide increasingly greater degrees of on-Site and subsurface consfruction, and therefore present increasing concem with short-term effectiveness as it pertains to worker health and safety. However, Altematives 3 and 5 are more effective than Altematives 1 and 2 in the short-term, since they provide for more aggressive source removal of Site contaminants in the soil and/or groundwater in the AST Area. Altemative 3 is more effective in the short-term than Altematives 4 and 5, considering it can be readily implemented. Altemative 4 is unlikely to be significantly more effective than the other Altematives in the FPP Area in the short-term, given the low mass of chloroform and the cunent rate of natural biodegradation. Long-Term Effectiveness and Permanence All five altematives afford a similar degree of long-term effectiveness and permanence for groundwater. However, Altemative 1 does not provide a monitoring component to verify the long-term effectiveness of natural attenuation. Altematives 2 and 5 will allow Site contaminants to remain in the AST Area for a greater period of time than Altematives 3 and 4; however, off- Site risks to human health and the environment are not expected with any Altemative. A permanent remedy will be achieved more quickly by Altematives 3, and 4, since a large mass of contaminants will be removed more quickly from the soil and groundwater rather than by reliance on natural biological and physical processes. Altematives 3 and 4 are expected to perform similarly in the long term. Golder Associates 400078 I p w June 2001 -74- 003-6016 Reduction of toxicity, mobility, and volume through treatment All five remedial altematives provide reduction of toxicity, mobility and volume through treatment by natural biodegradation processes to convert ethylbenzene, xylene, and chloroform to intermediate fransformation products, and eventually, to non-toxic final products. For Altematives 3, 4, and 5, active removal will occur via SVE/AS and/or groundwater exfraction, but freatment may not be required to comply with emissions standards. For example, based on Spring 2000 data, it is likely that groundwater extracted from the FPP Area (i.e., Altemative 4) may already meet discharge standards without freatment. Consequently, minimal benefit in reducing toxicity aiid volume would be realized through groundwater exfraction and freatment. Also, chloroform emissions from the air sfripper are not expected to require freatment. Natural attenuation, which is a component of Altematives 1, 2, 3, and 5, will not result in mass transfer of contaminants from groundwater to as part of the freatment processes. Implementability In general, all five altematives are implementable. Altemative 1 is the simplest to implement, followed in order of ease by Altematives 2, 3, 5, and 4, considering that an operational system for Altemative 3 exists.. However, materials, services, and equipment associated with the implementation of each remedial altemative are generally available on the mainland and on larger islands such as Puerto Rico. More specialized equipment such as the low profile air stripper (i.e., Altematives 4 and 5) and associated spare parts are somewhat less widely available, and would need to be manufactured and shipped from the U.S. Therefore, a longer lead time would be required for certain equipment. Also, Altematives 3, 5, and 4 (in that order) are increasingly more intensive in terms of operations and maintenance than Altematives 1 and 2. Finally, although a Site security fence is present and would be maintained under all Altematives, vandalism and theft are significant concems at the Site; therefore, the installation of any additional equipment under Altematives 3, 4, and 5 will increase the risk of loss due to theft/vandalism and potentially inhibit the implementability ofthese altematives. Cost Costs for each remedial altemative increase in the following order: Altemative 1, Altemative 2, Altemative 3, Altemative 5, and Altemative 4. However, most of the costs for the SVE/AS system associated with Altematives 3 and 4 have already been incurred as a result of the Treatability Study. Golder Associates 400079 I I I I I I I p I I I I I I I I June 2001 - 7 5 - 003-6016 Summary The following table provides a summary of the relative rankings of the five remedial altematives for each of the seven NCP criteria. Altematives assigned a rank of "First" were considered to be the most preferable in the associated category (i.e., least cost, most effective, most easily implemented, etc.). Relative Ranliing First* Second Tfiird Fourtfi Fiftii Protection of Human Health and Environment Alt. 3, 4 - Alt. 5 Alt. 2 Alt. 1 Compliance With ARARs Alt. 2, 3, 4, 5 - - - Alt. 1 Short-Term Effective- ness Alt. 3 Alt. 5 Alt. 4 Alt. 2 Ah. 1 Long-Term Effective- Ness Alt. 3,4 - Ah. 5 Alt. 2 Alt. 1 Reduction of Toxicity, Mobility, Volume Alt. 3, 4 (AST Area) Alt. 3 (FPP Area) Alt. 4 Alt. 5 Alt. 1,2 - Implementability Alt. 1 Alt. 2 Alt. 3 Alt. 5 Alt. 4 Cost Alt. 1 Alt. 2 Alt. 3 Alt. 5 Alt. 4 * Indicates most preferable alternative(s) in given category. g:\projects\003-6016\golder\feas.study(fs)\fs report\fs-june 200I\fstext.doc Golder Associates 400080 I I I I I I t I I I I I I I I I June 2001 -76- 003-6016 8.0 REFERENCES 2000. Revised Final Remedial Investigation Report. Prepared for Berlex Laboratories and Pharmacia & Upjohn, October 2000. Altematives for Ground Water Cleanup. National Academy Press: Washington, D.C, 1994. de Marsily, G, 1986, Quantitative Hydrogeology: Groundwater Hydrology for Engineers, Academic Press Inc. Golder Associates Inc., 2000, Remedial Investigation Addendum, July 2000. Golder, 2000. Draft Soil Vapor Exfraction / Air Sparging (SVE/AS) Pilot Study Report, October 2000. Harding-Lawson Associates, 1994. Remedial Investigation Draft Work Plan, Virgin Island Chemical Site, August 5, 1994. Harding-Lawson Associates, 1995. Draft Phase li Remedial Investigation Work Plan, Virgin Island Chemical Site, November 21, 1995. Harding-Lawson Associates, 1997. Draft Remedial Investigation Work Plan Addendum - Phase III, Virgin Island Chemical Site, January 20, 1997. Harding-Lawson Associates, 1997. Revised Draft Remedial Investigation Work Plan - Phase III, Virgin Island Chemical Site, July 25, 1997. Howard, P.H, R.S. Boethling, W.F. Jarvis, W.H. Meylan, E.M. Michalenko, "Handbook of Environmental Degradation Rates", CRC Press LLC, 1991. Mackay, D. and Shiu, Wan-Ying, A Critical Review of Henry's Law Constants for Chemicals of Environmental Interest, J. Phys. Chem. Ref Data, v. 10, n.4, 1981. Marley, M.C. and Bruell, C.J., In Situ Air Sparging: Evaluation of Pefroleum Industry Sites and Consideration for Applicability, Design and Operation. API Publication #4609, April, 1995. McCarty, P. L., 1997. Biotic and Abiotic Transformations of Chlorinated Solvents in Ground Water. In Proceedings of the Symposium on Natural Attenuation of Chlorinated Organics in Ground Water, USEPA ORD Document EPAy540/R-97/504, May 1997. pp7-l 1. McLaren/Hart, Inc., 1999. Feasibility Study Technical Memorandum, Virgin Island Chemical Site, March 1999. McLaren/Hart, Inc., 1999b. Draft Final Treatability Study Work Plan, Virgin Island Chemical Site, May 1999. McLaren/Hart, Inc., 2000. Final Remedial Investigation Report, Virgin Island Chemical Site, St. Croix, U.S. Virgin Islands, February, 2000. [Portions of this report were modified by Golder and submitted, unatfributed, as the Revised Final Remedial Investigation Report in October 2000]. Golder Associates 400081 I p i I June 2001 -77- 003-6016 Nyer, Evan U. and Suthersan, Suthan S., 1993, "Air Sparging: Savior of Ground Water Remediations or Just Blowing Bubbles in the Bath Tub?" Ground Water Monitoring and Remediation, Fall 1993, p. 87-91. Presumptive Remedy: Supplemental Bulletin Multi Phase Extraction Technology for VOCs in Soil and Groundwater, USEPA Directive No. 9355.0-68FS, Apnl 1997. USEPA, 1986. Superfund Public Health Evaluation Manual. Office of Emergency and Remedial Response. EPA/540/1-86/060. October, 1986. USEPA, "Confrol of Air Emissions from Superfund Air Sfrippers at Superfund Groundwater Sites", OSWER Directive 9355.0-28, June 15, 1989 USEPA, 1993. "Presumptive Remedy: Site Characterization and Technology Selection for CERCLA Sites With Volatile Organic Compounds in Soils," USEPA Directive No. 9355.0-48FS, September 1993. USEPA, 1996. Soil Screening Guidance: Users Guide, 2"'' Ed, USEPA Publication 9355.4-23, July 1996. USEPA, 1996. USEPA Region 11 Standard Operating Procedure "CLP Organics Data Review and Preliminary Review" SOP# HW-6, Rev II, June 1996. USEPA, 1997. Bioscreen -Natural Attenuation Decision Support System : Version 1.4. United States Environmental Protection Agency. Office of Research and Development. EPA/600/R- 96/087. Washington, DC 20460. July 1997. USEPA OSWER, 1999, "Use of Monitored Natural Attenuation at Superfund, RCRA Corrective Action and Underground Storage Tank Sites". Directive Number 9200.4-17. USEPA, 2000. "A Guide to Developing and Documenting Cost Estimates During the Feasibility Study." EPA 540-R-00-002, July 2000. Wiedemeier, T.H., M.A. Swanson, D. E. Moutoux, J. T. Wilson, D. H. Kampbell, J. E. Hansen and P. Haas, 1997, "Overview of the Technical Protocol for Natural Attenuation of Chlorinated Aliphatic Hydrocarbons in Ground Water Under Development for the U.S. Air Force Center for Environmental Excellence". In Proceedings of the Symposium on Natural Attenuation of Chlorinated Organics in Ground Water, USEPA ORD Document EPA/540/R-97/504, May 1997. pp37-61. Xu, Moujun and Eckstein, Y. "Use of Weighted Least-Squares Method in Evaluation of the Relationship Between Dispersivity and Scale," Joumal of Ground Water Vol. 33, No. 6, pp. 905 - 908.1995. Golder Associates 400082 % r November 2000 Table 1 Summary of Calculated Risks Virgin Island Chemical Site 003.6016 o o o 00 OJ Receptor Cun-ent - Adult Trespasser Cun-ent - Pre-adolescent Trespasser Future - Adult Resident Future - Child Resident Future - Adult and Child Resident' Future - Industrial/Commercial Worker Future - Consloiction Worker Reasonable Maximum Exposure I Cancer Risk/ Hazard Index 1.E-06 Hl= 5.3E.Q2 3.E.07 Hl= 2.5E-02 5.E-07 Hl= 1.6E-01 1.E-07 Hl= 7.5E.02 8.E^)4 Hl= 2.5E+02 4.E-04 Hl= 6.0E+02 1.E^)3 9.E-04 Hl= 3.3E+02 3.E-06 HI=1.3E.01 6.E-07 HI=6.1E-02 7.E-07 Hl= i.2E+oa 2.E-07 HI=5.6E-01 Media Analyzed Surface Soil Soil/Sediment (Gut System) Surface Soil Soil/Sediment (Gut System) Groundwater Groundwater Groundwater Groundwater Surface Soil Soil/Sediment (Gut System) Surface Soil Soil/Sediment (Gut System) Contaminants' with Significant Risk Arsenic - - Chloroform Arsenic Iron Manganese Methylene Chloride Chlorofomi Methylene Chloride Arsenic Iron Manganese Chloroform Methylene Chloride Arsenic Chloroform Methylene Chloride Arsenic Arsenic - 7 - Exposure Pathways Ingestion^ Damnal Contact inhalation Ingestion Demial Contact Inhalation Ingestion Demial Contact Inhalation Ingestion Dermal Contact Inhalation Ingestion^ Demial Contact^ Inhalation^ Ingestion^ Dermal Contact Inhalation^ Ingestion^ Dennal Contact^ Inhalatiort' Ingestion^ Demial Contact^ Inhalation' Ingestion^ Demial Contact Inhalation Ingestion Dermal Contact Inhalation Ingestion Dermal Contact Inhalation Ingestion Dermal Contact Inhalation Central Tendency | Cancer Risk/ Hazard Index 1.E-07 NC NC NC 9.E-05 HI=8.2E+01 1.E-04 1-11= 2.0E+02 2.E-04 2.E-04 Hl= 3.3E+02 5.E-07 NC NC NC NC HI=2.5E-01 NC NC Media Analyzed Surface Soil Soil/Sediment Surface Soil Soil/Sediment Groundwater Groundwater Groundwater Groundwater Surface Soil Soil/Sediment Surface Soil Soil/Sediment Contaminants' with Significant Risk - - - - Chlorofomi Manganese Arsenic Chlorofomi Methylene Chloride Arsenic Iron Manganese Chloroform Methylene Chloride Arsenic Iron Chlorofonm Arsenic - - - - Exposures Pathways Ingestion Dermal Contact Inhalation Ingestion Dermal Contact Inhalation Ingestion Demial Contact Inhalation Ingestion Dermal Contact Inhalation Ingestion' Dermal Contact' Inhalation' Ingestion' Demial Contact Inhalatior^ Ingestion' Demial Contact' Inhalation' Ingestion' Demial Contact' Inhalatiorf^ Ingestion Dermal Contact Inhalation Ingestion Dermal Contact Inhalation Ingestion Demial Contact Inhalation Ingestion Dermal Contact Inhalation Notes: 1. Only those contaminants exceeding a 1E-6 cancer risk or HI = 1 are listed. 2. Denotes exposure pathways within a media where the calculated risk exceeded a 1E-6orHI = V 3. - indicates no contaminants are contributing significant risk to the receptor. 4. Pre-adolescent trespassers are those between 7 and 12 years of age. 5. Risks and hazards include contributions from the contribution of methylene chloride and acetone. The presence of these analytes in samples is a result of blank contamination and does not represent site conditions, 6. MC indicates the central tendency risks/hazards were not calculated because the RME risks were below benchmartt levels. 7. Although in cumulative risk exceeds 1. individual risks are all <1. 8. Cumulative non-carcinogenic risks for adult and child residents are calculated separately. p:/003.6016;goldef/ts/ Tl)n xls revised: Octobr 24, 2000 Golder Associates I June 2001 W 003-6016 Table 2 Preliminary Remediation Goals VICHEM Site, St. Croix, USVI Constituent of Concern Groundwater Chloroform Arsenic Ethylbenzene Methylene Chloride Xylene Surface Soil Arsenic Iron Manganese Subsurface Soil i Acetone Ethylbenzene Xylenes Preliminary Remediation Goal 80 ug/I 50 ug/I 700 ug/I 5 ug/I 10,000 ug/I 3.83 mg/kg 31,933 mg/kg 1,600 mg/kg 8,000 ug/kg 6,500 ug/kg 90,000 ug/kg Reference Agreement between USEPA, Berlex, and P&U; Proposed MCL 40 CFR Part 141 - Primary MCLs 40 CFR Part 141 - Primary MCLs 40 CFR Part 141 - Primary MCLs <'' 40 CFR Part 141 - Primary MCLs Risk Based Calculation based on future industrial worker exposure *^' Two times background concentration per Final Rl Report McLaren/Hart, 2000) Risk Based Calculation (via ingestion) (McLaren/Hart, 2000) SSL DAF 10 SSLDAF 10 No SSL has been established for total xylenes so the most conservative isomer (o-xylene) has been used; DAF 10 Notes: (1) - The methylene chloride data presented in the Final Rl Report (M/H, 2000) showed results below the Contract Required Quantitation Limit that were neither changed to the Sample Quantitation Limits nor correctly qualified. Qualifiers of "BJ", "B", or simply "J" were used rather than the correct qualifier, which is "U" (non-detect). (2) - The PRG is a site-specific, risk-based concentration developed using site-specific exposure assumptions for the future industrial/commercial worker. The PRG was calculated using the intake value from Table 8.11a of the Risk Assessment, using a 1E-06 end point and a ratio of the intake. See also "Summary of Calculated Risks" table herein. ^ 003-6016\FSReporl\FSJune2001\Tbl2.xls Golder Associates Page 1_of 1_ 400084 November r J w ^ % r 003-6016 TABLE 3 ESTIMATED DRAWDOWN, PUMPING RATE AND WELL SPACING IN FPP AREA Hydraulic Conductivity Thickness Transmissivily Well Pumping Rate Hydraulic Gradient Stagnation Point Coordinates (y=0) Width of Capture Zone Precipitation Recharge forRo Calculation Radius of Influence Water Level above Base of Aquifer No Pumping Conditions Pumping Conditions Drawdown Distance for Well 1 Pumping Yes Well Diam,=| O.SO Distance for Well 2 Pumping Reinjection 2y ro = IQJW R)l Ho h h = [Ho'-Qln(ro/r);(iiK)]" D = Ho-h Well Spacing 100.00 [fl/sl I lft/day| I [cm/sT |ft'/day] |gpm| llff/day) [WU] M. m ifti [ft/day| I [inch/year J L UNCONFINED AQUIFER 3,4E-05 2,95 1 04E-03 150 44,23 0,80 154 0012 46 145 290 6,0E-04 264 285 15.00 jo Overall Drawdown (by superposition)! 10,93 10,14 10.59 10,93 11,21 11,46 11.69 11.91 12,11 12.31 12,49 12.68 12,85 13,03 13,20 13,36 13,53 13,69 13,85 14.01 14,16 14.32 14,47 14,52 14.77 14.92 -4,07 -4,86 -4,41 -4,07 -3,79 -3.54 -3,31 -3,09 -2,89 -2,69 -2.51 -2.32 -2,15 -1,97 -1.60 -1.64 -1,47 -1,31 -1,15 -0.99 -0,84 -0,68 -0.53 -0,38 -0.23 -0.08 0,60 0,18 0.32 0,50 0.73 1,02 1.41 1.91 2,57 3,42 4,52 5,96 7,83 10.25 13,41 17,52 22,85 29,79 38,81 50,53 65,77 85,68 111,33 144.81 188,34 244,92 -0,50 -0,18 -0,32 -0,50 -0,73 -1,02 -1,41 -1,91 -2,57 -3.42 -4,52 -5.96 -7.83 -10,26 -13,41 -17,52 -22,85 -29,79 -38,81 -50.53 -65.77 -85,58 -111,33 -144.81 -188.34 -244,92 100,50 100,18 100,32 100.50 100,73 101,02 101,41 101.91 102.57 103.42 104,52 105,96 107,83 110,26 113,41 117,52 122,85 129.79 138.81 150.53 165,77 185,58 211.33 244,81 288.34 344.92 99,50 9982 99,58 99,50 99,27 98,98 98.59 98.09 97,43 95,58 95,48 94,04 92,17 89,74 86,59 82,46 77,15 70.21 61,19 49,47 34.23 14,42 -11,33 -44,81 -88,34 -144,92 o o o 00 cn G:\003-6016\golder\FS\PufnpsindTr1\FPP wells upper alluvium.xls\Drawdown Unconfined Golder Associates November 1^ r 003-6016 TABLE 4 ESTIMATED DRAWDOWN, PUMPING RATE AND WELL SPACING IN AST AREA Hydraulic Conductivity Thickness Transmissivity Well Pumping Rate Hydraulic Gradient Stagnation Point Coordinates (y=0) Width of Capture Zone Precipitation Recharge forRo Calculation Radius of Influence Water Level above Base of Aquifer No Pumping Conditions Pumping Conditions Drawdown Distance for Well 1 Pumping Well Diam.= 0 50 Yes Distance lor Well 2 Pumping Reinjeclion T = K b 2y ro = [Q/(n R)] • Ho h h = lHo'-Qlii(ro/r))(itK)l ° D = Ho-h Well Sapcing 100 00 |(t/5| I ItUdayj I |Cfn/s| JUL (fl'/day) Igpml H'l^/day- |ft;fi| l"l l»l I l"l (ft/day) [(inch/year l"l _EL JEL J L J L J L UNCONFINED AQUIFER 2,1E-04 17,86 6 30E-03 150 267,91 3 60 673.8 0«16 67 210 419 6.0E-04 264 ', 595 100,0 Distance Iteetl oOverall Drawdown (by superposition) 11,83 11,31 11,60 11,83 12,02 12,19 12,34 12.49 12,63 12,77 12,90 13,03 13.15 13,27 13,40 13,51 13,63 13,75 13,85 13,98 14,09 14,20 14.31 14,42 14,53 -3,17 -3,69 -3.40 -3,17 -2,98 -2,81 -2,66 -2.51 -2.37 -2,23 -2,10 -1,97 -1,85 -1,73 -1,60 -1,49 -1,37 •1,25 -1,14 -1,02 -0,91 -0,80 -0,69 -0,58 -0,47 0,50 0.18 0,32 0,50 0,73 1.02 1.41 1,91 2,57 3,42 4,52 5.95 7.83 10.26 13,41 17,52 22.85 29.79 38,81 50,53 65.77 85.58 111.33 144.81 188,34 -0,50 -0,18 -0,32 -0,50 -0,73 -1,02 -1,41 -1,91 -2,57 -3.42 -4.52 -5,95 -7,83 -10,26 -13,41 -17,52 -22,85 -29,79 -38,81 -50.53 -65,77 -85,58 -111,33 -144.81 -188.34 100.50 100,18 100,32 100,50 100.73 101,02 101,41 101,91 102,57 103,42 104,52 105,96 107,83 110,26 113,41 117,52 122,85 129,79 138,81 150.53 165,77 185,58 211,33 244,81 288,34 99,50 99,82 99,68 99.50 99.27 98,98 98.59 98.09 97.43 96,58 95,48 94,04 92,17 89.74 86,59 82,48 77,15 70.21 61,19 49,47 34 23 14.42 -11.33 -44,81 -88,34 o o o 00 003.6016\Gol(lei\FS\PumpandTft\AST wells upper alluvium,xIS\Drawr]own Unconfined Golder Associates Page: Page OF IJ I June 2001 003-6016 w Table 5 Preliminary Cost Estimate - Alternative No. 1 No Action Virgin Island Chemical Site P Activity Estimated Cost EXISTING DIRECT CAPITAL COSTS | Fence Installation Total Existing Direct Capital Costs TOTAL DIRECT CAPITAL COST ESTIMATED INDIRECT CAPITAL COSTS Gen. Engineering Services (15%) Permitting/Regulatory Coordination (3%) Implement Health & Safety Plan (20%) Construction Oversight/QA/QC (20%) Contingency (30%) TOTAL CAPITAL COSTS O & M COSTS General Site Maintenance Fence Repair TOTAL ANNUAL Site Maintenance O & M COST PRESENT WORTH General Site Maintenance (30 YEARS @ 7%) TOTAL O&M COST FOR THIS ALTERNATIVE COST OF REMEDY $45,000 $45,000 $0 $0 $0 $0 $0 $45,000 $1,000 $1,000 $12,000 $12,000 $57,000 ^ 003-6016\FS\FS-June2001\Tbles5-7REV,xls, Table 5 Golder Associates Paae 1 of 1 400087 I June 2001 W Table 6 Preliminary Cost Estimate - Alternative No.2 Monitored Natural Attenuation Virgin Island Chemical Site 003-6016 P V Activity Cost EXISTING DIRECT CAPITAL COSTS | Fence Installation Total Existing Direct Capital Costs ESTIMATED DIRECT CAPITAL COSTS Monitored Natural Attenuation Monitoring Wells (5) General IVlobilization/Demobilization for Drilling TOTAL DIRECT CAPITAL COST ESTIMATED INDIRECT CAPITAL COSTS Gen. Engineering Services (15%) Permitting/Regulatory Coordination (3%) Implement Healtli & Safety Plan (20%) Construction Oversight/QA/QC (20%) Contingency (30%) TOTAL CAPITAL COSTS O & M COSTS General Site Maintenance Fence Repair TOTAL ANNUAL Site Maintenance O & M COST PRESENT WORTH General Site Maintenance (30 YEARS @ 7%) Monitored Natural Attenuation - Annual Mobilization/Demobilization IDW Disposal TOTAL ANNUAL MNA Mob/Demob and IDW Costs PRESENT WORTH MNA Mob/Demob and IDW (15 Years @ 7%) Sampling (15-well network at $1,913/well/event): Year 1, quarterly: Present Worth (1 yr @7%) Years 2-3, semiannually: Present Worth (2 yrs@7%) Years 4-15, annually: Present Worth (12 yrs @ 7%) TOTAL PRESENT WORTH, Annual Sampling Monitored Natural Attenuation O & M COSTS One Time - Yr Seven Well Rehabilitation TOTAL One Time Monitored Natural Attenuation O & M COST PRESENT WORTH (7th YEAR @ 7%) TOTAL O&M COST FOR THIS ALTERNATIVE COST OF REMEDY $45,000 $45,000 $12,000 $50,000 $62,000 $9,300 $1,860 $12,400 $12,400 $18,600 $161,560 $1,000 $1,000 $12,410 $10,000 $5,000 $15,000 $138,620 $107,000 $97,000 $186,000 $390,000 $10,400 $10,400 $6,500 $545,530 $707,000 003-60l6\FS\FSJune2001\Tbles5-7REV.xls. Table 6 Golder Associates Paae 1 of 1 400088 I June 2001 P Table 7 Preliminary Cost Estimate - Alternative No. 3 Air Sparging/SVE and Monitored Natural Attenuation Virgin Island Chemical Site Activity EXISTING DIRECT CAPITAL COSTS Fence Installation Existing SVE Pilot System (actual costs incurred) Total Existing Direct Capital Costs ESTIMATED DIRECT CAPITAL COSTS A i r S p a r q e / S V E Wells & Accessories Below Ground Conveyance System Mechanical & Controls Compressor & Blowers Monitored Natural Attenuation MNA and Groundwater Monitoring Wells (5) General Mobilization/Demobilization for Drilling TOTAL DIRECT CAPITAL COST ESTIMATED INDIRECT CAPITAL COSTS Gen. Engineering Services (15%) Permitting/Regulatory Coordination (3%) Implement Health & Safety Plan (20%) Construction Oversight/QA/QC (20%) Contingency (30%) TOTAL CAPITAL COSTS O & M COSTS General Site Maintenance Fence Repair TOTAL ANNUAL Site Maintenance O & M COST PRESENT WORTH General Site Maintenance (30 YEARS @ 7%) Cost $45,000 $520,000 $565,000 $40,000 $5,000 $20,000 $25,000 $12,000 $50,000 $152,000 $22,800 $4,560 $30,400 $30,400 $45,600 $850,760 $1,000 $1,000 $12,410 003-6016 I 003-6016\FS\FSJljne200nTbles5-7REV.xls, Table 7 Golder Associates Page 1. of 2 . 400089 I June 2001 W Table 7 Preliminary Cost Estimate - Alternative No. 3 Air Sparging/SVE and Monitored Natural Attenuation Virgin Island Chemical Site 003-6016 P Activity Soil Vaoor Extraction/Air Sparqinq: O & M cost for Year 1 Mobilization/Demobilization Monitoring and Testing - soil vapor, off-gas, dissolved oxygen, pressures, flows Trailer Utility Services (Gas/Electric) TOTAL ANNUAL SVE/ AIR SPARGING O & M COST PRESENT WORTH SVE/AIR SPARGING (1 yr @7%) Monitored Natural Attenuation Mobilization/Demobilization IDW Disposal TOTAL ANNUAL MNA Mob/Demob and IDW O & M COST PRESENT WORTH Monitored Natural Attenuation (15 YEARS @ 7%) Monitored Natural Attenuation - Samplina Year 1, quarterly: Present Worth (1 yr @ 7%) - AST and FPP Areas Years 2-3, semiannually: Present Worth (2 yrs @ 7%) - AST and FPP Areas Years 4-15, annually: Present Worth (12 yrs @ 7%) - FPP Area only TOTAL PRESENT WORTH MNA Sampling Monitored Natural Attenuation O & M COSTS One Time - Yr Seven Well Rehabilitation TOTAL One Time Monitored Natural Attenuation O & M COST PRESENT WORTH (7th YEAR @ 7%) TOTAL O&M COST FOR THIS ALTERNATIVE COST OF REMEDY Cost $20,000 $15,000 $10,000 $3,210 $42,000 $90,210 $84,350 $10,000 $5,000 $15,000 $136,620 $107,000 $97,000 $122,000 $326,000 $10,400 $10,400 $6,480 $565,860 $1,417,000 b 003-6016\FS\FSJune2001\Tbles5-7REV.xls, Table 7 Golder Associates Paae.2.of2 400090 I June 2001 003-6016 w p Table 8 Preliminary Cost Estimate - Alternative 4 Air Sparging/SVE/Groundwater Extraction and Treatment Virgin Island Chemical Site 1 Activity EXISTING DIRECT CAPITAL COSTS Fence Installation Existinq SVE Pilot System (actual costs incurred) TOTAL EXISTING DIRECT CAPITAL COSTS ESTIMATED DIRECT CAPITAL COSTS Air Soarqe/SVE Wells & Accessories (3 new AS wells) Below Ground Conveyance System Mechanical & Controls Compressor & Blowers Groundwater Extraction and Treatment Extraction and Discharge Treatment Setup Monitoring Wells General Mobilization/Demobilization for Drilling TOTAL DIRECT CAPITAL COST ESTIMATED INDIRECT CAPITAL COSTS Gen. Engineering Services (15%) Permitting/Regulatory Coordination (3%) Implement Health & Safety Plan (20%) Construction Oversite/QA/QC (20%) Contingency (30%) TOTAL CAPITAL COSTS O & M COSTS General Site Maintenance Fence Repair TOTAL ANNUAL Site Maintenance O & M COST PRESENT WORTH General Site Maintenance (30 YEARS @ 7%) Soil VaDor Extraction/Air Sparqinq: O & M cost for 1 year Mobilization/Demobilization Analytical Testing Trailer Utility Services (Gas/Electric) TOTAL ANNUAL SVE/ AIR SPARGING O & M COST PRESENT WORTH SVE/AIR SPARGING (1 YEARS @ 7%) Cost $45,000 $520,000 $565,000 $24,000 $3,000 $12,000 $25,000 $150,000 $69,000 $15,000 $50,000 $348,000 $52,200 $10,440 $69,600 $69,600 $104,400 $1,219,240 $1,000 $1,000 $12,410 $6,000 $10,000 $7,500 $3,210 $42,000 $68,710 $84,240 % G:/003.6016/FS/FSJune200l/lbl8«9REV,Klsfrabte 8 . GETiAS Golder Associates 400091 I June 2001 003-6016 % Table 8 Preliminary Cost Estimate - Alternative 4 Air Sparging/SVE/Groundwater Extraction and Treatment Virgin Island Chemical Site Activity Extraction and Air Stripping Equipment O&M Cost Mobilization/Demobilization Compliance/Performance Monitoring and Sampling - soil vapor, off-gas and (pre-) treated water IDW Disposal Trailer Utility Services (Gas/Electric) Permits TOTAL ANNUAL Extraction and Air Stripping O & M COST PRESENT WORTH Extraction and Air Stripping (5 YEARS @ 7%) Groundwater Monitoring (MNA and Extraction System) -Year 1, quarterly: Present Worth (1 yr @ 7%) -Years 2-3, semi-annually. Present Worth (2 yrs @ 7%) -Years 4-7, annually, 8 wells only, Present Worth (4 yrs @ 7%) PRESENT WORTH Annual Sampling Cost $26,000 $15,000 $75,000 $5,000 $3,210 $10,000 $1,000 $135,210 $554,360 $107,000 $97,000 $42,320 $246,320 TOTAL O&M COST FOR THIS ALTERNATIVE COST OF REMEDY $877,330 $2,097,000 p h G:/003-6016;FS/FSJune2001/lbl8i9REV,xls/Table 8 - GETSAS Golder Associates 400092 I % June 2001 Table 9 Preliminary Cost Estimate - Alternative 5 MNA/Groundwater Extraction and Treatment Virgin Island Chemical Site 003-6016 P ^ Activity EXISTING DIRECT CAPITAL COSTS Fence Installation Existinq SVE Pilot Svstem (actual costs incurred) TOTAL EXISTING DIRECT CAPITAL COSTS ESTIMATED DIRECT CAPITAL COSTS MNA Monitoring Wells Groundwater Extraction and Treatment Extraction and Discharge "Freatment Setup Monitoring Wells General Mobilization/Demobilization for Drilling TOTAL DIRECT CAPITAL COST ESTIMATED INDIRECT CAPITAL COSTS Gen. Engineering Services (15%) Permitting/Regulatory Coordination (3%) Implement Health & Safety Plan (20%) Construction Oversite/QA/QC (20%) Contingency (30%) TOTAL CAPITAL COSTS O & M COSTS General Site Maintenance Fence Repair TOTAL ANNUAL Site Maintenance O & M COST PRESENT WORTH General Site Maintenance (30 YEARS @ 7%) Monitored Natural Attenuation Mobilization/Demobilization IDW Disposal TOTAL ANNUAL Mob/Demob & IDW O & M COST PRESENT WORTH Mob/Demob & IDW (15 YEARS @ 7%) Monitored Natural Attenuation - Annual Sampling (8 wells) -Year 1, quarterly: Present Worth (1 yr @ 7%) -Years 2-3, semi-annually. Present Worth (2 yrs @ 7%) -Years 4-15, annually. Present Worth (12 yrs @ 7%) PRESENT WORTH Annual Sampling Cost $45,000 $520,000 $565,000 $12,000 $150,000 $69,000 $15,000 $50,000 $296,000 $44,400 $8,880 $59,200 $59,200 $88,800 $1,121,480 $1,000 $1,000 $12,410 $10,000 $5,000 $15,000 $136,620 $57,000 $52,000 $99,000 $208,000 G:/FS/FSReport/FSJune2001/tbl8&9REV.xls/Table 9 . GETSIUINA Golder Associates 400093 I June 2001 w Table 9 Preliminary Cost Estimate - Alternative 5 MNA/Groundwater Extraction and Treatment Virgin Island Chemical Site 003-6016 P Activity Monitored Natural Attenuation O & M COSTS One Time - Yr Seven Well Rehabilitation TOTAL One Time Monitored Natural Attenuation O & M COST PRESENT WORTH (7 YEARS @ 7%) Extraction and Air Strippinq Equipment O&M Cost Mobilization/Demobilization Monitoring and Sampling IDW Disposal Trailer Utility Services (Gas/Electric) Permits TOTAL ANNUAL Extraction and Air Stripping O & M COST PRESENT WORTH Extraction and Air Stripping (5 YEARS @ 7%) Groundwater Extraction/ Treatment Monitorlnq (7 wells) -Year 1, quarterly: Present Worth (1 yr @ 7%) -Years 2-3, semi-annually. Present Worth (2 yrs @ 7%) -Years 4-7, annually. Present Worth (4 yrs @ 7%) PRESENT WORTH Annual Sampling Cost $12,000 $12,000 $7,480 $26,000 $10,000 $75,000 $5,000 $3,210 $10,000 $1,000 $130,210 $533,860 $50,000 $45,000 $37,000 $132,000 1 TOTAL O&M COST FOR THIS ALTERNATIVE COST OF REMEDY $1,030,370 $2,152,000 w G:/FS/FSReporVFSJune2001/lbl8&9REV,xls/Table 9 . GET&MNA Golder Associates 400094 I p w REFERENCE 1.) MAP TAKEN FROM U.S.G.S. 7.5 MINUTE QUADRANGLE OF CHRISTIANSTED. VIRGIN ISLANDS. 2000 scale 2000 feet 003-6016 AM ^ 0 ^ E AS SHOWN 11/07/00 US01-029 DR SUBHUE: 03 GoUer Associaies SITE LOCATION MAP VIRGIN ISLAND CHEMICAL SITE 1 m a\ o o o I p < T . O CD X CO > LLI K ^ r i r~i I 7 I l - l l - l 1^1 1 1 1— m 1 1— 1 r^ 1 1— 00 1 1— 1 ^- 0 1 1— 1 AST AREA r~i r-1 r"n r~i r'n r~i r~i r~i n PAD IC!| f2l 1*1 121 ISl IC:| 121 121 ISl ' l^il l^i.1 leil \^\ \<!-\ \ l \ \<!-\ l^il IH^I L . J t - J U . J U . J U . J C J U . J U - J L._J CONCRETE PADS n / I ' / EARTHEN BERM DRIVEWAY UNPAVEO GENERATOR BUILDING [7- SUMP AD I d ¥ ^ FORMER R/0 UNIT AND WATER STORAGE MAINTENANCE BUILDING PADS I PAD I D CONCRETE I TRENCH COOLING TOWER // I) LL •TOWER I OPEN I REACTOR [Q _L ° I FORMER PROCESS PIT (FPP) AREA COOLING _ L . TOWER ffl FORMER LABORATORY PIT- LABORATORY UNPAVED ' / CONCRETE I iLOADING DOCK EXCAVATED AREA, L_. CISTERN WAREHOUSE STORAGE PAD SCALE '1 PAD D PIT ^ - / / / / LEGEND STORMWATER INLET EXISTING ABOVEGROUND STORAGE TANK LOCATION CZD / \ FORMER ABOVEGROUND STORAGE TANK \ \ LOCATION REFERENCE 1.) DRAWING BASED ON FIGURE 2 - 2 OF THE R.I. REPORT ENTITLED "MONITORING WELL LOCATION MAP" DATED 1 / 1 1 / 9 9 , BY McLAREN/HART, INC. 50 scale 50 feet k «'^.r..«.S' 003-6016 AM .>0'^ IT AS SHOWN 06/18/01 US01-027 DR SUBTITLE: 03 Golder Associates FACILITY LAYOUT VIRGIN ISLAND CHEMICAL SITE 400096 I p >• < X o CO (O (/) UJ \ TW-5 X ."rw-4 MW-10 LEGEND / PRODUCTION WELL LOCATION SHALLOW MONITORING WELL LOCATION DEEP MONITORING WELL LOCATION STORMWATER INLET EXISTING ABOVEGROUND STORAGE TANK LOCATION FORMER ABOVEGROUND STORAGE TANK LOCATION < A > < ^ NOTES CROSS-SECTION LOCATION 1.) MONITORING WELL LOCATIONS ARE APPROXIMATE. REFERENCE 1.) DRAWING BASED ON FIGURE 3 - 7 OF THE R.I. REPORT ENTITLED "MONITORING WELL LOCATION MAP" DATED 1/11/99, BY McLAREN/HART. INC. 50 scale 50 feet WVER GUT / 003-6016 AM So^ AS SHOWN Ql/TI/tX> US01-026 D« SUBTITIZ: 03 Golder Associates MONITORING WELL LOCATION MAP VIRGIN ISLAND CHEMICAL SITE o\ o o o I A NW AST T-10 MW-6 PROJECTED 25 ft. N 40-1 SBAST-10 30 20 I < > 10- P 0 - -10- - 2 0 - - 3 0 k - 4 0 - ^ PROJECTED 30 ft. N TW-02 TW-03 ''^p>^^m^^^- 30 0 30 LOWER ALLUVIAL AQUIFER WAREHOUSE FENCE APPROXIMATE ORIGINAL TOPOGRAPHY RIVER GUT A' SE - 3 0 CLAY (INCLUDES SANDY CLAY, CLAYEY SAND, AND SILTY CLAY AND ADMIXTURES) ^ GRAVEL GEOLOGIC CONTACT UNDETERMINED APPROXIMATE ORIGINAL GROUND SURFACE FROM U.S. GEOLOGICAL SURVEY OPEN FILE REPORT WRl 82-262 (1963) NOTE: PATTERNS FOR LITHOLOGIC UNITS OVERLAY EACH OTHER IN UNITS WITH MIXED LITHOLOGY. •.-^p 40 20 10 Ul I < > LU 10 - - 2 0 - - 3 0 - 4 0 horizontal scale 10 0 feet 10 A \ CROSS SECTION A-A' vertical scale feet JOB No,: 003-6016 AM OQ,.. i£_ AS SHOWN 07/27/00 US01-030 OR SUBTITLE: 03 Golder Associates COMPOSITE HYDROGEOLOGIC SECTION A-A" VIRGIN ISLAND CHEMICAL SITE 400098 I p w Hydrographs for wells in FPP Area -4 I—a •—I , 1—m B—\—B. 1/22/98 1/24/98 1/26/98 1/28/98 1/30/98 2/1/98 Date a B- 2/3/98 2/5/98 2ni9a 0.00 2/9/98 2/11/98 •MW-7 (Deep) + MW-2 (Shallow) —»-Rainfall JOB No: DRBY; CHK BY: REV BY: 003-6016 DSL DSL SAS SCALE AS SHOWN ^''^^ 07/27/00 ''""^''° Hydrographs.XLS DIRECTORY: Golder\FS\Hydrogeo Golder Associates HYDROGRAPHS FOR SHALLOW AND DEEP WELLS IN FPP AREA VIRGIN ISLAND CHEMICAL SITE 1'''°^'^^ 5 cn a\ o o o I p w Hydrographs for wells in AST Area 0.5 4 I—& 0.18 0.00 1/22/98 1/24/98 1/26/98 1/28/98 1/30/98 2/1/98 Date 2/3/98 2/5/98 2/7/98 2/9/98 2/11/98 • MW-8 (Deep) + MW-6 (Shallow) - Rainfall JOB No,: DRBY: CHK BY: REV BY: 003-6016 DSL DSL SAS SCALE: AS SHOWN DATE: ,__,»„ 07/27/00 FILE No Hydrographs.XLS DIRECTORY: Golder\FS\Hydrogeo Golder Associates HYDROGRAPHS FOR SHALLOW AND DEEP WELLS IN AST AREA VIRGIN ISLAND CHEMICAL SITE FIGURE: /» o o H O o 'Si* I CARINO PROPERTY / ® MW-10 (10.65) \ CLEME^" QNTRON (PROPERTY OWNER) \ X r— X X X ITI I7I 7 l-^l l^^l K UJ UJ L J / UNPAVED \ | ] M W - 8 ^ MV^-6 (10,5§)~ *s> CD _ l ^ MW-6 (10,53) 0 S 0 B @ S TANK FARM! J > MW-1 I ^ ^ (10,58) ^•^ r-1 n n r i r-i r-i r-i n IS!1 121 1*1 ISl ISl I t I ISl 121 ISl l^il Ihil 1^1 Ifil l»l| 1.11 l.il l»i-l l.i.1 U J I—J U J U J I . J l^J U J U J U J CONCRETE PADS PAD P-2 / 1 1 yji EARTHEN BERM , DRIVEWAY P a: o UJ b \ \ bU^ \ F GENERATOR BUILDING MW-13 / O COOUNG ^ .=^ TOWER ^^^ ^ ^ 1 /' / WATER \ " ^ ^ " ^ ^ \ I MAINTEN/llCE BUILOIIIG / CONCRETE n I 4 A / I TRENCH / I I OPEN I I , REJCTOR , I 10^- O I °PT 1°"^ o \ 'n ni I PROCESS I V J V ^ * ! /PRi ROCESS PIT AREA ^ , J h — LABORATORY UNPAVED CONCRETE _MW-^ dW-g I ] ""[=-,=11 « Jl MW-4 (10.56) EXCAVATED AREA i < .LOADING * l DOCK WAREHOUSE A R E ^ ' - ^ — ^ - ^ \ k ^ ^ - 2 ^ CENTRIFUGE L I PAD SCALE LEGEND / / I I I CHARUE'S CONCRETE PRODUCTION WELL LOCATION SHALLOW MONITORING WELL LOCATION DEEP MONITORING WELL LOCATION STORMWATER INLET (16.42) EXISTING ABOVEGROUND STORAGE TANK LOCATION FORMER ABOVEGROUND STORAGE TANK LOCATION SHALLOW GROUNDWATER CONTOUR SHALLOW GROUNDWATER ELEVATION (FT MSL) D \ MW-12 [ ] ^~~~~;M^y-11 (a98)"~ •V- PUMP BUILDING BUILDING ^ M \ ^ W (9,45) \ \ MW-5 / 1 0 . 6 5 GROUNDWATER ELEVATION (FT MSL) REFERENCE 1.) DRAWING TAKEN FROM FIGURE 4 - 6 OF THE R.I. REPORT ENTITLED "SHALLOW GROUNDWATER ELEVATION CONTOURS OCTOBER 2 1 , 1998" DATED 2 / 1 7 / 9 8 , AND WATER LEVEL MEASUREMENTS TAKEN ON OCTOBER 2 1 , 1998 BY McLAREN/HART, INC. li <K / 50 scale feet « ^ ? . - - ' ' / CHARUE'S CONCRETE 003-6016 AM CHK BY: 50- E AS SHOWN 07/28/00 US01-038 DR SUBTITLE: 03 Golder Assodales SHALLOW GROUNDWATER CONTOUR MAP -10/21/98 VIRGIN ISLAND CHEMICAL SITE - I GOLDEN GROVE ADULT CORRECTIONAL FACILITY ZENON C05TRUCTI0N COMPANY CATCHMENT AREA N i LEGEND dl BUILDING STREAM = ^ ^ ^ ROAD • • - — TREE LINE •^ APPROX. LOCATION OF OFFSITE WELLS -(j^ SHALLOW MONITORING WELL LOCATION ® ONSITE PRODUCTION WELL LOCATION n DEEP MONITORING WELL LOCATION — GROUNDWATER CONTOUR (FEET MSL) 7.75 GROUNDWATER ELEVATION (FEET MSL) REFERENCE 1.) DRAWING TAKEN FROM FIGURE 4 - 9 OF R.I. REPORT ENTITLED "DEEP GROUNDWATER ELEVATION CONTOURS OCTOBER 21, 1998". DATED 02/17/00 AND WATER LEVEL MEASUREMENTS TAKEN ON 10/21/98 BY McLAREN/HART, INC. 150 scale 150 feet CAD BY: CHK BY: REV BY: 003-6016 AM v; AS SHOWN 07/28/00 FILE No.: US01-037 DR SUBTITLE: 03 DEEP GROUNDWATER CONTOUR MAP -10/21/98 o o o Gcdder VIRGIN ISLAND CHEMICAL SITE 8 I w p b i to X 9 u / / - - 5 t ^ x UNPAVED \ \ \ y []MW-8 / t ^ ^ — X X x -— X X / - X 5 X ^ ^ ® MW-6_(18,51]_ ' / I ® MW-10 (18.37) ( - X X X X X X X - y K r i r i r—1 j — i r~i r i r n r—i<i—I r~l r~l •"-i i—» r~» r~\ r i r i r i r i r i 'PAD u ^ UJ L_J L_J ,L_J LJ LJ >L_J LJ CU LJ u j U J u j u j u j ^ J i.j u j C J \ ^ 1 \ ^ TANK FARhw M \ M W - 1 CONCRETE P A M T i ^ O J ^ ^(18.02) ^ P A W \ 1 DRIVE' s: <5» <3^ \ \ \ \ u N P A V E D \ SUMP PAD F k^ UNPAVED MW-13 ^ GENERA BUILDING \ I V t W - T J ^ \ (15.82) _ - . \ MW-14 ;A\R I nw^. \ MAINTENANCE BUILDING ^TOWER ^ _RE*CTOR I AR? I PROCESS AREA X / "7/ / TRENCH PROCESS PIT AREA CENTRIFUGE -a MW-: BUILDING (16.60) / UNPAVED CONCRETE 1W-9I] II MW-4 (17,33) EXCAVATED AREAJI <| .LOADING * l DOCK asTERtr* WAREHOUSE PAD crsffRiT*"''^ STORAPE / / SCALE \ • 11 \ • LEGEND / / / / . PAD„,-<- "-i / D PIT / 9 D S B CZZ) I \ \ I (16.42) NOTES PRODUCTION WELL LOCATION SHALLOW MONITORING WELL LOCATION DEEP MONITORING WELL LOCATION STORMWATER INLET EXISTING ABOVEGROUND STORAGE TANK LOCATION FORMER ABOVEGROUND STORAGE TANK LOCATION SHALLOW GROUNDWATER CONTOUR SHALLOW GROUNDWATER ELEVATION (FT MSL) .UNPAVED I W(1£ ' (15.23) MW-5 (16.44) / / 1.) FORMER PRODUCTION WELL P-1 IS ABANDONED. REFERENCE 1.) DRAWING BASED ON FIGURE 3 - 7 OF THE R.I. REPORT ENTITLED "MONITORING WELL LOCATION MAP" DATED 1/11/99, AND WATER LEVEL MEASUREMENTS TAKEN ON JANUARY 31, 2000 BY McLAREN/HART, INC. / / / 50 scale 50 feet 3*^t.-.uS' / JOB No.: 003-6016 CAD BY: AM CHK BY: REV BY: ^ 0 ' SCALE: AS SHOWN DATE: on/Ti/m n i £ No.: US01-033 OR SUBTITLE: 03 G<dder Associaies SHALLOW GROUNDWATER CONTOUR MAP -1/31/00 VIRGIN ISLAND CHEMICAL SITE n o o o •«4< I \ \ -x^ ^ — X \ \ \ A V ^ UNPAVED o 1/J2 \ \ \ -A f » DRIVEWAY \ r - \ r i I T I N I ^ I I -^ I I •'^ I U J c u \ * A in V [] MW-8 " sl.^1vi^-"6Tr7:iS)~ ® WW / / J - 10 (17.26) \ >. « MW-6 li''JO) 7 k i I d ° ^ >^"i i"i 1*1 i"i i"i i t i ISl 121 181 ^ K r r k J — - ^ i-i '•^i i-i i-i i^^i i-i i-i i-i i-i L J L J L J L_J u J UJ y~J ^ j UJ UJ UJ UJ U J y^j INK FARM M \ M W - 1 CONCRETE PADS PAD P-2 MW-1 (16,76) ^ :ARTHEN EARTHEN BERM / < \ t o " ^ I I ' ^ ^ \ \ \ UNPAVED •X. k \ \ SUMP » GENERATOR I BUILDING F \ MW-13® \ r y (14.92) „ V \ MW-14 MW-15 I—I I ] PADS ^•^D / i-^OWER : ^ • ^ X \ MAINTENANCE BUILDING \ \ AT • ^ CONCRETE \ \ I TRENCH N TRENCH |0"»Jo SlQ Js = I. , PROCESS ' I ^ ^ AREA I PROCESS PIT AREA I — : ^ ^ _ X'^iT"MW-7 \ LABORATORY RAMP \/ED/ / C0»I<^T1 lETE 1W-9 I] t ^ MW-4 (16,42) EXCAVATED A R E A ! < .LOADING * l DOCK \ \ aSTERN io_Qi < ^ n Mw^ - I >> i ( 1 5 , 6 2 ) ^ WAREHOUSE :n z. STORAGE PAD / / \ • —II fr I I SCALE / / LEGEND I; I ll I I PAD i \ ^ , 0 » I MW-12 I ] ^~-->lV\M1 V ^ (14.05) -*' \ \ b /I / D CZ] / \ \ / (16.42) NOTES PRODUCTION WELL LOCATION SHALLOW MONITORING WELL LOCATION DEEP MONITORING WELL LOCATION STORMWATER INLET EXISTING ABOVEGROUND STORAGE TANK LOCATION FORMER ABOVEGROUND STORAGE TANK LOCATION SHALLOW GROUNDWATER CONTOUR SHALLOW GROUNDWATER ELEVATION (FT MSL) / 1.) FORMER PRODUCTION WELL P - 1 IS ABANDONED. / / * / REFERENCE 1.) DRAWING BASED ON FIGURE 3 - 7 OF THE R.I. REPORT ENTITLED "MONITORING WELL LOCATION MAP" DATED 1/11/99, AND WATER LEVEL MEASUREMENTS TAKEN ON MARCH 6, 2000 BY McLAREN/HART. INC. / 50 scale 50 feet AS SHOWN 07/27/00 ni£ No.: US01-034 DR SUBTITLE: 03 Golder Associaies SHALLOW GROUNDWATER CONTOUR MAP - 3/6/00 VIRGIN ISLAND CHEMICAL SITE RGURE 10 o H O O I « MW-10 LEGEND P PRODUCTION WELL LOCATION SHALLOW MONITORING WELL LOCATION DEEP MONITORING WELL LOCATION STORMWATER INLET EXISTING ABOVEGROUND STORAGE TANK LOCATION FORMER ABOVEGROUND STORAGE TANK LOCATION SHALLOW GROUNDWATER CONTOUR SHALLOW GROUNDWATER ELEVATION (FT MSL) 1.) GROUNDWATER ELEVATION FOR WELL MW-15 WAS NOT USED IN CONTOURING, AS THIS WELL MAY NOT HAVE BEEN FULLY RECOVERED AT TIME OF MEASUREMENT. 2.) FORMER PRODUCTION WELL P-1 ABANDONED. REFERENCE 1.) DRAWING BASED ON RGURE 3 - 7 OF THE R.I. REPORT ENTITLED "MONITORING WELL LOCATION MAP" DATED 1/11/99. AND WATER LEVEL MEASUREMENTS TAKEN ON MARCH 6, 2000 BY McLAREN/HART, INC. 50 scale 50 feet w RW/ER GUT X 003-6016 MJS X ) i E AS SHOWN 07/27/00 US01-035 DR SUBTITLE: 03 Golder Assodafes DEEP GROUNDWATER CONTOUR MAP - 3/6/00 VIRGIN ISLAND CHEMICAL SITE 11 ID O H O O I ® MW-10 P CD CD O >- < X o X (/) z < > LU > r NOTES b 1.) SOIL BORING LOCATIONS ARE APPROXIMATE. 2.) SOIL BORINGS SHOWN WITHIN SHADED AREA EXHIBITED DETECTIONS OF ETHYLBENZENE AND XYLENE ABOVE MGW SSLS (DAF=10) REFERENCE 1.) DRAWING BASED ON RGURE 4-11 OF THE R.I. REPORT ENTITLED "ESTIMATED AREAL EXTENT OF IMPACTED SOIL - AST AREA" DATED 2/17/00, PROVIDED BY McLAREN/HART. INC. SBAST-10 SBAST-6 MW-8 SBAST-7 SBAST-1 I r~T SBAST-12 I <H I I K, I I T I I T I I - I I - I L_J L_J ^SBB-6 MW-1/SBB-1 SBAST-9 ,SBAST-3 r~i r~i r~T i 7 I I"-1 L_J EARTHEN BERM SBB-16 SBB-15 MW-15 D LEGEND D I \ \ I PRODUCTION WELL LOCATION SHALLOW MONITORING WELL LOCATION DEEP MONITORING WELL LOCATION SOIL BORING SAMPLE LOCATION EXISTING ABOVEGROUND STORAGE TANK LOCATION FORMER ABOVEGROUND STORAGE TANK LOCATION APPROXIMATE AREA OF IMPACTED SOIL ABOVE SSLs 40 scale 40 feet 003-6016 MJS 'JO ^^ AS SHOWN 11/07/00 US01-022 DR SUBTITLE: 03 Golder Associaies ESTIMATED AREAL EXTENT OF IMPACTED SOIL - AST AREA VIRGIN ISLAND CHEMICAL SITE RGURE 12 vo o H o o • l» .TW-4 TW-2 TW-5, TW-3 ® MW-10 'TW-1 P b (10 u) MW-81] ® (5^4)00) r 1 I -J r 1 i^ J r 1 r ~l I J i J r 1 I J r 1 I J I 1 I I 1 TANK FARM M W - 1 . '(40.1( I J I J CONCRETE PADS f 1 o CM I H- l > PAD P-2 / / / / / \ \ \ ,GWPP-34 WALL X T ^ • • ^ - ^ MAINTENANCE BUILDING ^ y CONCRETE EARTHEN BERM ) RAMP CONCRETE UNPAVED SCALE STORAGE PAD / / / / / / / SAMPLE ID MW-1 MW-6 MW-8 MW-10 P-2 GWPP-34 DEPTH (ft bgs) 23-33 17.4-26.7 63-73 22-32 UNKNOWN 32-35 CONCENTTiATION (ppb) TOLUENE - 460 UJ ETHYLBENZENE - 16,000 XYLENE - BO.OOO TOLUENE - 600 UJ ETHYLBENZENE - 20,000 XYLENE - 98,000 TOLUENE - 0.2 UJ ETHYLBENZENE - 17 XYLENE - 79 TOLUENE - 1 U ETHYLBENZENE - 0.8 UJ XYLENE - 5 U TOLUENE - 1 U ETHYLBENZENE - 1 U XYLENE - 7 U TOLUENE - 8 ETHYLBENZENE - 10 U XYLENE - 13 SAMPLE ID 1W-1* TW-2* TW-3* TW-4* TW-5* DEPTH (ft bgs) 19-29 19-29 19-29 22-32 20-30 CONCENTTATION (ppb) TOLUENE - 5 U ETHYLBENZENE - 8,000 E XYLENE - 15,000 E TOLUENE - 5 U ETHYLBENZENE - 5 U XYLENE - 5 U TOLUENE - 5 U ETHYLBENZENE - 7Z0 J XYLENE - 5 U TOLUENE - 5 U ETHYLBENZENE - 5 U XYLENE - 5 U TOLUENE - 5 U ETHYLBENZENE - 3 J XYLENE - 5 U NOTES: J U E 18,000 ESTIMATED CONCENTRATION ANALYTE NOT DETECTED ABOVE REPORTING LIMIT ESTIMATED CONCENTRATION CONCENTRATION EXCEEDS MCL (ETHYLBENZENE - 700 ppb, XYLENE - 10,000 ppb) CONCENTRATIONS FROM TEMPORARY WELLS ARE SCREENING RESULTS FROM ONSITE GC (SEPTEMBER 1997) ALL RESULTS ARE FROM MARCH/APRIL 1998 INVESTIGATION EXCEPT SCREENING RESULTS FROM TEMPORARY WELLS (SEPTEMBER 1997) LEGEND E PRODUCTION WELL LOCATION SHALLOW MONITORING WELL LOCATION DEEP MONITORING WELL LOCATION - ^ GEOPROBE GROUNDWATER SAMPLE LOCATION X TEMPORARY WELL LOCATION — 5 — XYLENE CONTOUR (ppb) ( ) EXISTING ABOVEGROUND STORAGE TANK LOCATION C U D FORMER ABOVEGROUND STORAGE TANK LOCATION NOTES 1.) FOR COMPARISON. CONCENTRATIONS FROM THE MAY 2000 SAMPUNG EVENT ARE REPORTED IN PARENTHESES NEXT TO WELL ID. ALL UNITS ARE ppb. REFERENCE 1.) DRAWING BASED ON RGURE 4 - 1 2 OF THE R.I. REPORT ENTITLED "ESTIMATED AREAL EXTENT OF XYLENE-IMPACTED SHALLOW GROUNDWATER - AST AREA" DATED 2 / 1 7 / 0 0 , PROVIDED BY McLAREN/HART. INC. 30 scale 30 feet 003-6016 MJS •bQ-v AS SHOWN 11/07/00 RLE No.: US01-023 DR SUBTITLE 03 Golder Associates ESTIMATED AREAL EXTENT OF XYLENE-IMPACTED SHALLOW GROUNDWATER IN 1998 - AST AREA o iH O O VIRGIN ISLAND CHEMICAL SITE 13 I ^ 9 W TW-5, .TW-4 ® MW-10 TW-2 MAINTENANCE BUILDING SAMPLE ID MW-1 MW-6 MW-8 MW-10 P-2 GWPP-34 DEPTH (ft bgs) 23-33 17.4-26.7 63-73 22-32 UNKNOWN 32-35 CONCENTRATION (ppb) TOLUENE - 460 UJ ETHYLBENZENE - 18,000 XYLENE - 80.000 TOLUENE - 600 UJ ETHYLBENZENE - 20,000 XYLENE - 98.000 TOLUENE - 0.2 UJ ETHYLBENZENE - 17 XYLENE - 79 TOLUENE - 1 U ETHYLBENZENE - 0.8 UJ XYLENE - 5 U TOLUENE - 1 U ETHYLBENZENE - 1 U XYLENE - 7 U TOLUENE - 8 ETHYLBENZENE - 10 U XYLENE - 13 SAMPLE ID TW-1* TW-2* TW-3* TW-4* TW-5* DEPTH (ft bgs) 19-29 19-29 19-29 22-32 20-30 CONCENTRATION (ppb) TOLUENE - 5 U ETHYLBENZENE - 8,000 E XYLENE - 15,000 E TOLUENE - 5 U ETHYIBFNZENE - 5 U XYLENE - 5 U TOLUENE - 5 U ETHYLBENZENE - 720 J XYLENE - 5 U TOLUENE - 5 U ETHYLBENZENE - 5 U XYLENE - 5 U TOLUENE - 5 U ETHYLBENZENE - 3 J XYLENE - 5 U NOTES: J U E 18.000 r 1 i > r 1 r 1 oo T L J I J CONCRETE PADS t 1 o I I— >• J PAD 7 p-2 / / I I I I UNPAVED / / CONCRETE SCALE STORAGE PAD / / / ESTIMATED CONCENTRATION ANALYTE NOT DETECTED ABOVE REPORTING LIMIT ESTIMATED CONCENTRATION CONCENTRATION EXCEEDS MCL (ETHYLBENZENE - 700 ppb, XYLENE - 10,000 ppb) CONCENTRATIONS FROM TEMPORARY WELLS ARE SCREENING RESULTS FROM ONSITE GC (SEPTEMBER 1997) ALL RESULTS ARE FROM MARCH/APRIL 1998 INVESTIGATION EXCEPT SCREENING RESULTS FROM TEMPORARY WELLS (SEPTEMBER 1997) LEGEND PRODUCTION WELL LOCATION SHALLOW MONITORING WELL LOCATION DEEP MONITORING WELL LOCATION ^ GEOPROBE GROUNDWATER SAMPLE LOCATION X TEMPORARY WELL LOCATION —700— ETHYLBENZENE CONTOUR (ppb) ( ) EXISTING ABOVEGROUND STORAGE TANK LOCATION C I I ] FORMER ABOVEGROUND STORAGE TANK LOCATION NOTES 1.) FOR COMPARISON. CONCENTRATIONS FROM THE MAY 2000 SAMPUNG EVENT ARE REPORTED IN PARENTHESES NEXT TO WELL ID. ALL UNITS ARE ppb. REFERENCE 1.) DRAWING BASED ON FIGURE 4 - 1 3 OF THE R.I. REPORT ENTITLED "ESTIMATED AREAL EXTENT OF ETHYLBENZENE-IMPACTED SHALLOW GROUNDWATER - AST AREA" DATED 2 / 1 7 / 0 0 . PROVIDED BY McLAREN/HART. INC. 30 scale 30 feet 003-6016 MJS V^r AS SHOWN 11/07/00 US01-024 DR SUBTITLE: 03 Gidder Associates ESTIMATED AREAL EXTENT OF ETHYLBENZENE-IMPACTED SHALLOW GROUNDWATER IN 1998 - AST AREA VIRGIN ISLAND CHEMICAL SITE 14 00 o H O O I % p w SAMPLE ID GWPP-7 GWPP-8 GWPP-9 GWPP-10 GWPP-11 GWPP-12 GWPP-13 GWPP-14 GWPP-15 GWPP-16 GWPP-17 GWPP-19 GWPP-20 GWPP-21 GWPP-23 GWPP-24 GWPP-25 GWPP-26 GWPP-27 GWPP-28 GWPP-29 * GWPP-30 GWPP-31 GWPP-32 GWPP-33* GWPP-34 GWPP-35 GWOR-1 MW-2 MW-3 MW-7 MW-11 MW-12 MW-13 MW-14 P-1 MW-15 DEPTH (ft bgs) 20-25 20-25 22-27 28-33 21-26 26-31 22-30 21-24 8-10 27-30 27-32 8-12 23-28 21-26 22-27 23-28 24-29 6-10 24-29 26-31 31-34 34-37 22-27 23-28 31-34 32-35 27-30 22-29 18.9-28.2 18.5-28.5 64-74 30-40 137-147 30-40 124-134 UNKNOWN 88-98 CHLOROFORM CONCENTRATION (ppb) ND ND 318 94 74 78 157 ND 1,178 ND 3 480 7 ND 1,000 53 3 54 3.994 234 96 ND 1.661 6 63 ND 29 31 2,400 ND 4 3J ND ND ND 46E SEE NOTE 1 NOTES: E J ND 1,700 * MW-13© ^ •' (10 u) ^ / MW-14 I ] , GWPP (10 U) MW-15 n (9.4 J) "J LEGEND EXCEEDS CALIBRATION RANGE OF INSTRUMENT ESTIMATED CONCENTRATION NON DETECTED CONCENTRATION EXCEEDS MCL (80 ppb) FOR PREPARATION OF PLUME MAP, RESULTS FROM SCREENING POINTS GWPP-29 AND GWPP-33 WERE REPLACED WITH RESULTS FROM MONITORING WELLS MW-11 AND MW-13 RESPECTIVELY. THESE PERMANENT POINTS ARE ASSUMED TO BE MORE REPRESENTATIVE OF ACTUAL GROUNDWATER CONDITIONS. ALL RESULTS ARE FROM MARCH/APRIL 1998 INVESTIGATION EXCEPT MONITORING WELLS MW-11 THROUGH MW-14 (OCTOBER 1998) AND MW-15 (MAY 2000). ^ PRODUCTION WELL LOCATION ® SHALLOW MONITORING WELL LOCATION C DEEP MONITORING WELL LOCATION •^ GEOPROBE GROUNDWATER SAMPLE LOCATION -80— CHLOROFORM CONTOUR (ppb) NOTES 1.) FOR COMPARISON, CONCENTRATIONS FROM THE MARCH AND MAY 2000 SAMPUNG EVENT ARE REPORTED IN PARENTHESES NEXT TO WELL ID. ALL UNITS ARE ppb. REFERENCE 1.) DRAWING BASED ON RGURE 4 - 1 6 OF THE R.I. REPORT ENTITLED "ESTIMATED AREAL EXTENT OF CHLOROFORM-IMPACTED SHALLOW GROUNDWATER - AST AREA" DATED 2 / 1 7 / 0 0 . PROVIDED BY McLAREN/HART, INC. 30 scale 30 feet 003-6016 MJS 5o. E AS SHOWN 11/07/00 US01-025 DR SUBTITLE: 03 Golder Associates ESTIMATED AREAL EXTENT OF CHLOROFORM-IMPACTED SHALLOW GROUNDWATER IN 1998 - PROCESS PIT AREA o H o o VIRGIN ISLAND CHEMICAL SITE 15 Novembi Diirooo Figures 00^016 Historic VOCs at FPP Area 7000 o o h-» l-» o •MW-2: Chloroform 28-Oct-95 15-May-96 Ol-Dec-96 19-Jun-97 05-Jan-98 24-Jul-98 09-Feb-99 28-Aug-99 15-Mar-OO 01-Oct-OO Date Figs16&17,xlsFIG16 Golder Associates August ^mo Figur^r7 OOTB016 o o 140000 120000 100000 3 s o 80000 « 60000 s o U 40000 20000 15-Jun-94 Historic VOCs at AST Area •—MW-1: Ethylbenzene MW-1: Xylene j ; . . MW-6: Ethylbenzene ^i MW-6: Xylene ^^ Sparge Test Sparge Test Begins 28-Oct-95 ll-Mar-97 24-Jul-98 Date 6-Dec-99 19-Apr-Ol Golder Associates August c 111 Figures c Model vs. Actual Xylene Concentrations Downgradient of Source 1-D Advection/Dispersion with Linear Sorption (upper curve), with First-Order Decay (half-life = 150 days) 140000 120000 100000 D) C 0 ra *^ c 0) 0 c 0 0 80000 60000 MW-1 40000 - 20000 INTERPRETED INTERPRETED GWPP-34 50 100 150 Distance from MW-6 [ft] 200 250 o o M M to ast-xyl.XLS Degradation t1/2 = 150 days Advection/Dispersion/Sorption • Mar-29-00 • 10/98 Xylene Cone. Along Plume Axis • Mar-09-00 9 May-03-00 Golder Associates I August 2000 Figure 19 Predicted Xylene Concentrations Downgradient of MW-6 c ( x , / ) = Steady State One-Dimensional Advection/Dispersion = e x d • 2 \ 2 D ) exp{- Bx)eifc where; x - t ^ ( U / < i a R F -¥4AD/aiR 2^Dt/a]R B = . J ( U / 2 D y -\-(A,caR/Dj Model with Reaction Terms (Degradation + exj^Bx)erfc x - \ - t ^ ( U / o j R F -i-4AD/ajR 2^Dt/eaR p Darcy Velocity Dispersivity Dispersion Coefficient Effective Porosity Initial Concentration Partition Coeficient Bulk Density Fraction of Organic Carbon Retardation Factor Decay Coefficient Half-Life Time Simulation Time Model Input Parameters U = KI Q L D = aL*U (0 Co Koc Pb Foe R = 1 + Koc*Foc* Pb/n X =(ln2)/t„2 tl/2 tl/2 t t 1.07E-01 50 5.36 0.2 120000 240 1.44 0.0027 5.67 0.004621 150 0.41 7300 20 [ft/day] [ft] [ft^/day] [Dimensionless] [ug/I] [cm'/g] [g/cm^ [Dimensionless] [Dimensionless] [day-'] [days] [years] [days] [years] i5:*?:i^6ob(iih •: lobboo:;- Wi/M ;;i::'^;;8oooo;j •:.v:..:\.>....:y.:: Wmm jiigjijebbpbj • : o . A m K y : ;;:;|i:;:-;:2bbbb;;H y : :;•': •.:,•,.;:;•.•.::•;.; :•;•••••', •';• W'-'-'-'-'-'^.'^^-y^-^. ] i W'^^'^^'-Wli iilas-i W : m : 9 S . y ^ f 0 y ^ ' W : y ^ W§§MM::::f^^ WfKIm 2^^:^^^ Cpnceim^rr „ ' : ^ : i >L^i^ i : :?;;:: ^"'^;••^^.^:•^•M •ityyyX^^yy^'yy^^^^^^ :•:•••:•:•'.- •'•'•• ' ' ^ ^ '••^•^'i^^V.v-'v/-;;:^' ' ^ y - : ' : . ' : : y^'-'V. > ]yiypyy:/<y: .-:• •:---:::\-:-y}:-y>:-:'- • % . . • " , • . . • . • " • • . . . :-y:mi:'''!y if:;:«,j,::|:::,:;.;:,:::.:::,:;.:S.x:;.^^ •::•••••;•:• •>i-:-:-:'?:-,r:::o..>':>::::.'::;: % \ . y . . . y y ' . . y y : ' . y . ' V y y / y y . :•. : Sii 4000;;; ii'ljlzbbb- •;;^:;iqpbp:;- ;;;|;;|jipbb:'y i::;;S;;;4bbb; ;5S;2o6pi ;;Si;;i;J;-;i;;:;i ':yW'':'yrf:::' ;;4 4; Expjbded^yi W::;??:S-g? ji^ ;:••.:;. ::MeLCoricentnition • :y:-;:y|;/ y : : ; N:'i'l-:4^v;i|4-i|i:i:;if;2;:^^ 5t?i4w|;;.;••. • SOyi '.i :: 1 ;4,:1 Op::, is• : j .fl'SOy ,>:* ';::s::;g*:;H:;:g:j4!5::.y..:;;;y ;;::':':>;:;:: yDistance:frqm'-MWi6'tfqx: ywrnm^sff^^^^^^^^^ : • : • : • : • : • : • ; • : • : . ; - : - : - : - y - > ^ ^ • • • • • ; . • • • • • • • , • . . . • . . „ : , • „ : . . : • , , • > , , : : : • . • • y-tMNyyy^^^^ ;;;:••:::;• J;i:::/:r.;;V-;x.f:;y?4HSi:?-l^ 4i4:::i;;*i;::j;::;;;:4:K:4.4^^C~:"^^^^ •\: •:' ,;l poi;; y-:' ':•: 'yy; '[gH': Jj; SL:!15b;:s||;; :y;,; • ;;||i: ^vi ;• ;;:-SJ-lpistartdgfiiiim^MW-i^[ft]7^ : :f' ill!!^i4t;-J^i--;;S: :i- i.20b: ii::::.:::::.:.i.i-iiiF-;;::4; WMSMi:. ;i:ii200:i:i4j,:i-:i',; ^j;i;'iliili-:;;|i|:4i -i-^'-Ji ••iiSiii2 y.\i 5oii; "'SBfM '•//...yM y . t / y j::y.:::' S S y lyy-M:: & • & • • • • ifiv;i;-ii;j ;,.; : V^; :1Vi^'2 'Oil b File: ast-xyl.XLS Golder Associates 400113 August ' 1^ Figur^O 10^016 Model vs. Actual Ethylbenzene Concentrations Downgradient of Source 1-D Advection/Dispersion with Linear Sorption (upper curve), with First-Order Decay (half-life = 100 days) 30000 25000 20000 o c o 2 15000 *^ c a> u c o 10000 5000 MW-1 MWr6 ISTBRJPRETED ""•GWPP^„ wf'isawssfli-iswsjsj.'a.'*.,,; 50 100 150 Distance from MW-6 [ft] 200 250 o o H J-* ast-ethl2.XLS — Degradation tl/2 = 200 days —Advection/Dispersion/Sorption A IVIar-29-00 • 10/98 Ethylbenzene Cone. Along Plume Axis • Mar-08-00 # May-08-00 Golder Associates I August 2000 Figure 21 Predicted Ethylbenzene Concentrations Downgradient of MW-6 C{x,t) = Steady State One-Dimensional Advection/Dispersion where: x - t . j ( U / a j R y -i-4XD/aJ{ 2 ^ D t / o ^ B = y j ( U / 2 D ) ^ -t-CAeaR/D) Model with Reaction Terms (Degradation + exp{Bx)eifc x-\-t4(U/coR)^ + 4 A D / a J t 24Dt/caR ) p •30000: 25000'. :ii;i'2pooo:i 15000- i10000; Darcy Velocity Longitudinal Dispersivity Dispersion Coefficient Effective Porosity Initial Concentration Partition Coeficient Bulk Density Fraction of Organic Carbon Retardation Factor Decay Coefficient Half-Life Time Simulation Time Model Input Parameters U = K I « L D = H L ' U (0 Co Koc Pb Foe R = 1 + Koc*Foc* •k = ( l n 2 ) / t , c t „ 2 t „ 2 t t Pb/n 1.07E-01 50 5.36 0.2 28000 240 1.44 0.0027 5.67 0.0069315 100 0.27 7300 20 [ft/day] [ft] [ft^/day] [Dimensionless] [ug/I] [cm^/g] [g/cm^ [Dimensionless] [Dimensionless] [day-^] [days] [years] [days] [years] ::20oo; :.i:i500: \.^^y:y.[,y\y ;:™::::loopi : " siSOOx ':Expiodedi:View-^: yyyyyyyyKy. '.-'- .yy^/ypyy.-.MCLCohcehtriition::' yyyyyyy-Siv. ,>:i\;i00;:;:.--::-,;;;:?:.::150::;:,:-: i:;pistanOBiTromiMWi^6j[ft]S .250:; :i:¥^ • ^ v ' VMCL-Cbhcciitratioil X ::50' ::i:lpb:S:;:?:i::H:':;-i:;i::s;vii:-:^:::si::::>: iJ:i::.i3ist|nci:ifromiMWT6i'[fq 2p0i f25p:^ w File: ast-ethl2.XLS Golder Associates 400115 August ^ ^ Figur?22 Dubois Model vs. Actual Chloroform Concentrations Downgradient of Source 1-D Advection/Dispersion with Linear Sorption (upper curve), with First-Order Decay (half-life = 100 days) 4500 4000 it 3500 3000 3 r 2500 .2 cs I. I 2000 o c o o 1500 1000 500 GWPP-27 I MW-2 \INTERPRETED QWP-IO A 50 GWPP-24 MW-11 GWPP-29 100 150 200 Disance from GWPP-27 [ft] 250 o o M M — Degradation tl/2 = 100 days Advection/Dispersion/Sorption • Mar-31-00 • 10/98 Chloroform Cone. Along Plume Axis • Mar-08-00 ® May-08-00 fpp-clfrm-100.XLS Golder Associates 7/28/00 2;56 PM I August 2000 003-6016 Figure 23 Predicted Chloroform Concentrations Downgradient of GWPP-27 C { x , t S t e a d y S t a t e O n e - D i m e n s i o n a l A d v e c t i o n / D i s p e r s i o n > 2 H^«J exp{— Bxjerfc where: x - t y j ( U / a ^ ) ^ -i-4AD/eaR 2 y l D t / a 3 R B = y j ( U / 2 D ) ^ + ( X o } R / D ) M o d e l w i t h R e a c t i o n T e r m s ( D e g r a d a t i o n + exp{Bx)erfc x - i - t ^ t U / c o R ) ^ + 4 M ) / a J i \ 2^Dt/iaR 1 p :i'i;-^5P0?T i:Ti:ii4bob' i*.iS3500i' :gi3bpp' "5). yyyy. ' ^ y y i=;: 25bbii :;i5oo: : ::;500: m^yy yX-y -y y>yyy y : Darcy Velocity Dispersivity Dispersion Coefficient Effective Porosity Initial Concentration Partition Coeficient Bulk Density Fraction of Organic Carbon Retardation Factor Decay Coefficient Half-Life Time Simulation Time Model Input Parameters U = K I " L D = aL*U (0 Co Koc Pb Foe R = 1 + Koc*Foc* X = ( l n 2 ) / t „ 2 t,/2 tl/2 t t Pb/n 2.01 E-02 1.04E+01 0.21 0.2 4000 31.00 1.44 0.0027 1.60 0.0069315 100 0.27 7300 20 [ft/day] [ft] [ft^/day] [Dimensionless] [ug/I] [cm'/g] [g/cm'] [Dimensionless] [Dimensionless] [day-'] [days] [years] [days] [years] =:Sl4b;: |;i;;12bii^ c^.ilbbi. : 0 . . • • • • • . . • : • : :^w':80^ % • : & '&yyAa\ •yyi-yyOy yMyyy[pyyypy.Mpy:y-yy .•••;•;'::•••• •^''•'••,'• :::'|-.- . - ^ P y y . y y y \\.y:UCt\Cmcama\Mmyy:,^:,yyy' .y ;•:50:.,:;:;;:?iijsi:;:;;;• AOOy;.v; •::::i:i:;:;iso;::..;• r-; i i-;i?;ii|iif bistanceiif rom ; G W P j ^ ^ 200:: ;;:250:: : ; M C L Concoitratibri :;.1op:;:;}.;:: •;;.;"t•.>•:;;• •' ; y y ' y y ^ s O y p Q i s t a n c x f r q m i l i ^ :;:250::, b File: fpp-clfrm-100.XLS Golder Associates H H o o August 2000 Figure 24 003-6016 XYLEl^E CpNCElVTRATrON ALONG PLUMK CFM KKLINT (IIIK/I. at /^O) ^_ X TYPE OF MODEL -,. " N o Degradation ,, 1st Order Decay '. Inst. Reaction • Field Data from Site , ' " ' • 0 .'• 119.475 119.475 119.475 98.000 I p.- l'-^ . .ip,:;l:-' 93.065 77.556 93.065 ;-'/i>20.£:|\ 74.761 51.706 74 761 80.000 ;;.;;;^.;:V%- 30 64 600 37 082 64 600 Distance from Source (ft) .C.40 : r 57 930 27.601 57 930 50.000 ^ • 5 0 - - ' 53 100 21 001 53.100 60 49 350 16.212 49.380 70 46 395 12.646 46 395 80 43 925 9.941 43.926 10.000 90 41 837 7 862 41 837 0.013 100 40 037 6.248 40.037 e o 1-^ ^ ex E s u u s o U 140 ^ 1st Order Decay -. ..V f=^Instantaneous Reaction 'No Degradation .ss'• FleldData from'.Site. 40 • •• - . 60 E)istancc From Source (ft) 80 1 0 0 '•• 120. % Calculate Animation I ime: 20 Years Return to Input Recalculate This Sheet O o H !-» CO Gxyie, Golder Associates August 2000 Figure 25 Total Xylenes Model Mass Balance 003-6016 Tmrisverse l>t&tance0 Model toptspiar__ f~~No Degradation I IVIodel \ ._- , / f ' l s t Order Decay \ I /Wode/ __ J Instantaneous ] Reaction M o d e l _ j ra Plume Mass if No Biodegradation [ H z l O ^ ^ ^ ^ (96 ^/i) CHan.e in Electron A o c e p | ^ ^ ^ ^ f / , ' / , y , ' / y M " ' ' " " j _ • Contam. Mass tn oouivc IL-- . , —^j^cT^ Corrtam Mass in source NOW (t=^20Years)LlllM (Kg) (Kg; plot r'". DJita (ft) 240 320 360 current Volume of Groundwater ir. ^ i " " ; ^ P ^ j l ^ J a X ; Flowrate ofWater Through source Z o n e L i i l L J ^ _ ^^ 1 Recalculate j rvlass HELP / plot D8t; ;ta > 1 arge- O o H H XI. „t - /inn ft for this calculation. Note: Model length set - 400 tt Tor in. Gxylene.xls Golder Associates August 2000 Figure 26 003-6016 V ETHYLBENZENE CONCENTRATION ALONG PLIMK CENTERLINE (mg/L at /.=«) Distance from Source (ft) TYPE OF MODEL No Degradation 1st Order Decay Inst. Reaction Field Data from Site 0 27 915 27.915 27.915 20.000 20 12 516 8.124 12 516 18.000 40 10.489 _ 4.402 10.489 60 •' ' 9 320 2.529 9.320 80 8.506 1.493 8 506 1.000 100 7 896 0.897 7.896 0.001 120 7415 0.545 7.415 140 7 023 0.334 7 023 160 6 695 0.207 6 695 180 6415 0.128 6415 200 6 169 0 080 6.169 3.0.000 25.000 u Calculate Animation FleldData frdmrSite-k' u 50 100 150 Distance From Source (ft) Time: 20 Years Return to Input 100 Recalculate This Sheet 250 o o h» to o Golder Associates July 2000 % Figure 27 Ethylbenzene Model Mass Balance 003-6016 o o h-» t o l-» Dht9nc0(f(} i 10Q 50 0 ^60 -10Q MASS FLWC (mofd^y) Q 0.000 0.000 27.915 0.000 OOOO 3.4E+4 Time;; 40 0.002 0.727 4.402 0.727 0.002 9.8E+3 JDISS<JI,.¥EP BVM0CAI5BOX CONCIN'I'HATIONS m FLUME inipLat 7Mn Dhtmc^ trom Sowce fft$ m 0.014 0.475 1.493 0 475 " 0014 4.1 E+3 1 20 Years | 120 0.019 0.236 0.545 0.236 0~019"" 1 8E+3 160 iiiiiiQiii 0 015 0.009 0.107 0.046 0.207 0.080 0.107 0.046 0.015 : 0.009 7.5E+2 1 3.2E+2 Target Level: iiiiiii 1 0 . 7 0 0 ^ 240 0.005 0.020 0.032 0.020 0.005 1 4E+2 280 0.002 0.008 320 0.001 0.004 0.013 • 0.005 0.008 0.004 36D 0.001 0.001 0.002 0.001 0.002 i 0.001 j 0.001 5.7E+1 1 2.4E+1 1 1.0E+1 mg/L Displayed ft*odel: 400 0.000 0.001 0.001 0.001 0.000 4.3E+0 list Order Decay Mtid0}txf0isp}$iy: r~ No Degradation Model I 1st Order Decay Model 1 ^ - Instantaneous Reaction Model . y J 30 000 [ Plot Paid :> Target ] 360 -100 Plume md $ourc^ Mm$m (Ofd^f-xtf^Mmf^tude Acum^cyj Flume Mass. if No Biodegradation] 203 9 \(Kg} ~ Actual Plume Mass] 5 5 \(Kg) * Plume Mass Removed tjy Btodeg 198.4 (Kg; (97 %> Change it> Electron Aceeptor/Svproduct Masses; Oxygen Nitrate Iron If Sulfate Methane na y.y,y-r.y^i'.y,yiy,y,y,yy,y,y,y,y,y,y,y,S'.y,y,it.y., na I na T"" na I na IfKg) Contam* Mass in Source (t*0 Years) Contam, Mass in Source Now (t=20YearB} Current Volume of GroiHidwater VR Plume Flowrate of Water Through Source Zone; L Mais HELP 608.0 404.1 3.1 0.691 r" ' 1 Re im (m (aa~ft) (ac-ff/yr) calculate Golder Associates August 2000 Figure 28 • • • • jam 003-6016 CHLOROFORM CONCENTRATION ALONG PLUME CENTERLINE (mg/L at Z=0) : TYPE OF MODEL No Degradation 1st Order Decay Inst Reaction Field Data from Site 0 4.000 _ 4.000 4.000 4.000 20 1.677 0.767 1.677 0.900 40 _ J.339 0.280 1.339 0.094 60 1.174 0.112 1.174 Distance from Source (ft) . 80 1.066 0.047 1.066 0.075 im 0.986 0.020 0.986 120 0.923 0.008 0.923 0.053 140 . 0.871 0.004 0.871 - 160 0.828 0.002 0.828 , 180 0.790 0.001 0.790 0.096 : 200 0.756 0.000 0.756 4.500 4.000 e S.500 I ^-^^^ % ^-500 S B-OOO o 1.500 ^ 1.000 0.500 0.000 1st Order Decay '^^^^^^ Instantaneous Reaction No Degradation FleldData from Site 50 100 150 Oistancc From Source (ft) Calculate Animation Time: 20 Years Return to Input 200 Recalculate This Sheet 250 o o M to to Golder Associates August 2000 " » Figure 29 Chlorofornn IVIodel Mass Balance 003-6016 Tr9fiW0r$0 mfimt\'£i} HVDMOCABBOX C0NCINTHATION& m n i M K (XDg/I.M IMX Di$t»m0 1^ 6Q 25 0 ' ' ^ -60 MASS FIWC (mg/ciay) (m 0 0.000 0.100 4.000 0.100 oooo 1 OE+3 Ttme; 20 OOOO 0.093 1 0.767 0 093 OOOO 5 8E+2 40 0 001 0 050 0.280 0 050 0 001 2 3E+2 1 20 Years 60 0.001 0.027 0.112 0.027 0.001 1 OE+2 Ta Dt$tmc0 i5ram So«r<?e (ft) 80 0.001 0.014 0.047 0.014 0 001 4 6E+1 rfet Level: 100 oooo 0.007 0.020 0.007 oooo 2 1E+1 1 0.100 120 oooo 0.003 0.008 0.003 OOOO 9.6E+0 mg/L 140 0.000 160 0.000 0.002 i 0.001 0.004 0.002 0.000 4.4E+0 0.002 0.001 oooo 2.0E+0 Displayed *utodel: 180 0.000 0.000 0.001 0.000 0.000 9 2E-1 200 0.000 0.000 0.000 oooo 0.000 4.2E-1 |lst Order Decay M0d$}p D}$pt&y: __ No Degradation Model 1st Order Decay Model ^... Instantaneous r ^ Reaction Model ^ -50 Plume md Smrc^ Ma$$^$ iOf4$f-i^f*Mmf^itud0 4ccaf8g>i^ Plume Nass if No Siodegradationj 7.6 \(Kg) - Actual Pll^me Massj 0 9 \(Kg) « Plume Mass Removed fiy Biodeg 6.7 im (88 %> Change in Electron Acceptor/Svproduct Masses; Oxygen Nitrate Iran It Sulfate Methane na ''lyyi^yyyv'^y^yii^yffymiffyy^iviy^yi __ 1 na I na I na I/Kg) 9ifff9>y'yi>09S9& Contam. Mass in Source (t««0 Years) Contam. Mass in Source Now (t=20Yeafs) Current Volume of Groundwater m Plume Flowrate of Water •^roagh Source Zone infinite Infinite 1 9 0.463 (m (ac-ft) (ac-ft/yr) -r I Recalculate F o o i-» to Golder Associates Novem^Booo ^ ^ ^ ^ ^ ^ H • • M j j ^ • • m • • • • WtM a i H ^ ^ ^ ^ ^ ^ ^ F FIG^PSO ^ " ^ ^ " ^ " ^ P " • • Transient BioscreeWknalysis - Xylene ^ ^ 6 0 1 6 Input Data o o M to BIOSCREEN Natural Attenuation Decision Support Svstem A}r force OenW for envtrmmemi Exc^fiBft^ L?.*:ry. ?>y«Xem 0.0 ^ 5.6 A)r Force Oentsr for £nvttmmeftt0l Exc^Hmoet 1, HYOROGEOIOOY Seepage Velocity* y^ or Hydraufio Conductive K Hydrauiic Gradient i Porosity f^ 2ril"lSJf»ER§rdN" ™^™^., ,,,- lon^ftydinal DisperaM^* stphan Transverse Dispersivity* alpha y Vertical Df^ersivity* ^ptja ^ Of Estin^afed piyme Length i ^ Retardaliot^ Factor* jF^ or Soil Bulk Denaty r/jo Partition Coefficient Koc FracteonOr^antcCarbon foe 4. BIObEGftADATldN ~" " 1st Order Decay Oo^ff* tamba^ or $olu^ Half-life t-h$}f orinstmtaa^ous /fea*^w» ftJorffef DelteOxysw* D Q Delta Nitrate* ^05 Ofa$erv6d Ferrous Iron* Fe^-i- Delta sulfate* $ Q 4 Observed Methane* ^^4 G./003-6Q16/Golder/FS Report/ Draft2/G)cyl98-00.xls/lnput V&r&iOfi 1.4 1 97.8 bfr-^^^=— 1 e.sE-dijI l O j O Q ^ ^""^2 {ft/yr) 4cm/$ec) m) 50.0 2.0 m (ft) MUm 1.44 240 0.002^7 1 26 IilLJfy»«''> (peryrj (mg/L) (nig/L) (mg/l) (m/Q (mg/L) Island Chemical IXWene ) 993-00 5, OE?\^eRAU Mojteled^ea Length* Modeled ^ e a Width* Simutatioft Time' B^niiSfp^ 200 200 '~2""" m ^ (») w {yr) ^ Data input Instructiortsr" Q H D 1. Snter value directly . or ^^ 2. CafCuM^ by flfttng tn grey cells bBlow. (To restore p ^ u s ^ j f r ^ U y l r i 'modeF'^' Variahte* _ V^itue ca/c(i/afed"i>y mod©/, 6»'SOiiftCE DATA " '~~ "~^~ ""• ~' — ^ — - (Poo'^enfer^nydafe), , > . . . , . ":^^.^*'"^*- . . . - " - a n d Input Concentration!, A w,Hth. 6 5 ' ' af?d Input Concentrations & Widths 1,2. and 3 Jn^ayrpBj^APL, Soj! 7. FIELD DATA FOR COJVtPARJSON Concenlratiofj <mg/g| 63 0^^400' Dist. from Source {fi)mKKSMmMSGr Vi&WQf Plume tvokmg Down Obs&md Cmt&rlme Condt^ntration^ st Monitoring Weth ffNo Data Leave Blank er Enter "0" ^' >5"?.^^?2^P^ ^P OUTPUT TO $€£: I """ i RUN ARRAY RUN CENTERLINE ^^.j L .^'®^.?"*P"* J ( View Output 1 Golder Associates ! f Recalcuiate f iils^ Paste Example Dataset ^ _ _ _ _ _ _ _ _ _ _ _ ^ J Restore Formulas for Vs, \ Pispersivities, R, lambda, other 1 November 2000 % Figure 31 Transient Bioscreen Analysis 2000 Data Match Xylene 003-6016 XYLENE CONCENTRATION ALOiycrPLlJiVIECENTERl.lNE (ing/L iit /=0) ' Distance from Source (ft) . • TYPE OF MODEL No Degradation 1st Order Decay Inst. Reaction Field Data from Site ' i : . " o •• - 63.526__ 63.526 , 63 526 63.000 20 39 630 35 913 39 630 40.000 40 28.876 18.244 28 876 60 18 252 8.478 18 252 ' '•-• 8 0 ' : -. 10 894 3911 10 894 x 100 6 058 1 758 6 058 0.001 - . 1 2 0 3 108 0.758 3 108 140 1 461 0.309 1 461 160 0 626 0.118 0 626 180 0 244 0 042 0 244 200 0 086 0.014 0.086 70 -I B g t e o U Calculate Animation •1st Order Decay Instantaneous Reaction • • No Degradation Field Data from Site 50 . 100 • •' 150 Distance From Source (ft) 200 250 Time: 2 Years Return to Input Recalculate This Sheet o o to cn Draft2/Gxyl98-00.xls/Centerline Output Golder Associates November 2000 Figure 32 Transient Bioscreen Analysis - Xylene Time to Compliance Simulation 003-6016 ,;..'" >;,. ;:t;;;,•'i"i-."'" .l"-' ' .'-. X Y L E N E CONCENTRArriON>L"ONG-^^^ (m«/L iit /=0) TYPE OF MODEL No Degradation 1st Order Decay Inst. Reaction Prelim. Remed. Goal . ? v , • ' • . , ' V < < 3 . ' - : 7 974 7.974 7.974 10.000 '5 / < ,. 20 : _ 7 976_ 4.617 7.976 10.000 40 , 7 667 2.495 7.667 10.000 ' •-. 60 7 586 1.391 7.586 10.000 Distance from Source (ft) 80- 7 679 0.795 7.679 10.000 *.>:;-ioo •;- J 889 0.462 7.889 10.000 -•'- ,120 8 184 0.272 8.184 10.000 140 ^8.541 0.162 8.541 10.000 160 8 945 0.097 8.945 10.000 180 9 385 0.059 9.385 10.000 200 9.849 0.035 9.849 10.000 &£ U s o ^ 1st Order Decay Instantaneous Reaction No Degradation PRG 50 100 -150 Distance From Source (ft) 200 250 Calculate Animation Time: 20 Years Return to Input Recalculate This Sheet o o UJ to G:/003-6016/Golder/FSReport/Draft2/ Fig32.xis/Centerline Output Golder Associates -I» November 2000 Figure 33 Transient Bioscreen Analysis - Ethylbenzene Data Input 003-6016 BIOSCREEN Natural Attenuation Decision Support System AirForc^ C^M^r for Bnvironrmntst Bxc^fhnc^ 1, HYDROGEOLOGY Seepage Velocity* or Hydraulic Conductivity Hydraulic Qradjeni Porosity 2. DISPERSION Longitudinal Dispersivtty* Transverse Disper^vily* Verftcal Disperst\4ty* or Estfmated Plume Length 3. ADSORPTION Retardation Factor* Of Salt Bulk Deiisity Partition Coefficient FracttonOrganfcCafbon Vs H f alpha X alpha y alpha z Lf> R rhe Koc foe 97.8 $.3e-03 0,003 0.2 50.0 5-Q- 00 # or 120 22 4 ^ or 1.44 ?1Q0 00027 (ft/yr) ((toy$« {ft/ft} {-) (fi) m m m (') {kg/}} (Ukg) « 4. 6l6DeGR"«3[Att6N 1 st Order Decay CoefP tamMa [ J 26 J (psr yr) er 1 ^ Solute Half-Life t-half j 0,$5 Uy^ar) or fftstanianeeue R^mtten ModBt Delta Oxygen* 0 0 Delta Nitra-te* N03 Observed ferrous Iron* /^e2+ Delta Sulfate* S04 Observed Methane* CH4 „ (mgA.) (rttg/L) {rng/l} (mg/L) V^r$fon 1 4 $. GEif7£RAL Modeled Area Length* Modeled Area Widtt^* Sfmutatiorj Time* \lsland Chemical \Ethvlbenzene 98-00 200 200_ 2 m f (ft) W {yr) * Run Name L Q02 Pma tnput fh$tnt<ftfims: ."..nil] 1. £nter value directly...,ar 2 Caleutate by filling in grey c0fls below. (Ta restore fo^rmuin% M hutton Mew) Variatjie* ^aiajisjed directly in model W m calculated by model (Dany enter any dat&J e. SOURCE DATA Source Thickness in Sat^^one* Source Zones; Width* ffl> Conc.(mg/Ly ^9....m Vertical Plane Source Look at Plume Cross-Section and Input Concentrations & Widths for Zones 1, 2, and 3 Soltiile Mass tn Source N/ifL, Soil View of Plume Loofang Daw/7 Observed Oenteriim Cancentr^iens at Momfodng Welts tfNQ Data leave Blank or Enter "0" 7. FIELD DATA FOR COMPARISON Concentration (mg/L)J Pjst Itom Source (ft)| 145 61 *, CHOOSE TYPE OF OMTPyT TO SEE? RUN CENTERLINE View Output I RUN ARRAY | V „ „..J 1^ View Output Recalculate This j Sheet J Paste Example Dataset ] y \._... /;; Restore Formulas for Vs, Dispersivities R, lambda, other ^ o o H G:/003-6016/Golder/FS Report/Draft2 Gethy98-00.xls/lnput Golder Associates November 2000 - » Figure 34 Transient Bioscreen Analysis - Ethylbenzene 2000 Data Match r 003-6016 ^••EtHYLBENZErHE-CaNCENTRATldN ALONG PLUME-CENTERLINE (mg/L';at:Z=0)'^ i TYPE OF MODEL ; No Degradation 1st Order Decay Inst, Reaction Field Data from Site 0 14,466 14.466 14.466 14.500 - 1 • - 20 - 6.011 4.258 6.011 - -- . _ ' - . ' ' Z ' - i • i .>-40 •'''! 2.209 0.868 2.209 . 1 ' . , - : ~ 3 0.577 0.152 0.577 0 100 Distance from Source (ft) .' '--80'' 0.103 0.021 0.103 100- 0.012 0.002 0.012 0.001 120 0.001 _ 0.000 0.001 , .~ 140•' - OOOO 0.000 0.000 .•:, :'.^.'160_,. 0 000 0.000 0.000 ...180;^;' 0.000 0.000 0.000 - 200 oooo 0.000 0.000 c o e <u w s o U DD '1st Order Decay Instantaneous Reaction • No Degradation Field Data from Site -o- 50 100 150 Distance From Source (ft) 200 250 Calculate Animation .Tiihe:i. .'• 2.0 Years V. Return to Input Recalculate This Sheet o o M IO 00 G:/003-6016/Golder/FS Report/Draft2 Gethy98-00.xls/Centerline Output Golder Associates November 2000 Figure 35 Transient Bioscreen Analysis - Ethylbenzene Time to Compliance Simulation 003-6016 ETHYLBENZENE CONCENTRATION ALONG P-LUiVlE.CENTERLINE (mg/L at Z=0) -. • i " c •i. o .4-t c '. 4> W s o • u ^ 0X1 != Instantaneous Reaction,. No Degradation 50 ' 100 150 Distance From Source (ft) 200 TYPE OF MODEL . No Degradation 1st Order Decay Inst. Reaction Prelim. Remed. Goal 0 0.667 0.667 0.667 0 700 20 0 925 0.316 0.925 0.700 " ."" \ " " ,' 40 1 577 0.156 1.577 0.700 ., 60 2 706 0.079 2.706 0.700 Distance from Source (ft) 80 4 591 0.041 4.591 0 700 100 5.634 0.015 5.634 0.700 ,. - . -120 4 381 0.004 4.381 0.700 140 3 324 0.001 3.324 0.700 160 2 455 0.000 2.455 0.700 180 1 761 0.000 1.761 0.700 200 1 225 0.000 1.225 0.700 250 Calculate Animation -Time: 21.0 Years Return to Input 'Recalculate This Sheet 1 ^ o o l-» t o vo G:/003-6016/Golder/FS Report/Draft2 Flg35.xls/Centerline Output Golder Associates Noven^KoOO F I G ^ p 3 6 Transient Bioscreen A n a l ^ ^ Chloroform (FPP Area) Data Input ^ K o i o BIOSCREEN Natural Attenuation DecUion Support System Atr Force CefitdrforSnm'cnmeeifal Bxceii^tice o o M U> O 1, HYOROGEOtOOY Seepage Velocity* or Hy<*a(^ Conducfivity Hydf au8o Gradient Porosity 2;i>lSPERSiON™ ™ Longtfi,idinal Disper sMty* Transverse Dispersivity* Verfical DJ^eravity* or Estimated PJyme length jrApioRpTiofr""'"' Retardation Factor* or Soil Bulk Density Partition Coefficient FracljonOrganicCarfeon 4. BtODEGRADATtON 1st Order Decay Coeff* O f Solute Half-life Vs K i n — ™ , „ ™„ fttphax affray ^ f ^ ^ Z i p • ' • " ~ * " - " ' R rho Koc foe fambtiB t-haff orinstantatKOUs fivatitfon Mottei Delta Oxygen* Delta Nitrate* Observed Ferrous fron* Delta Satfat^* Observed Methane* ' G:/003-6016/Golder/FS Gchlor98-00.xls/lnput. 0 0 N03 FeZ+ S04 QH4 Report/: 36.6 W 5.9e-04 %^\z \(m) {-) 0.2 (ft/yr) (cn^sec) I 10.4 0.0 I 180 V^V^^i^^^^^WV^ 1.6 5fr 1.44 31 0.0O267 1 2 77 0.2$ (ff) (ft) (ft) ('} {m} (Ukg) ('} (peryrj (y&^r) (mg/L) (mgJL) (mgA.) {mg/L} (mg/L) Ver&hn f.4 {Island Chemical Ichloroform 1998-00 Run N^me $. OENERAL Modeled Area length* Modeled Aiea Width* Simulation Tjme* 67 s6URCi"DATA 100 Ioo_ ' 2 (ft) f m w iyr} ^ Data tnputiastruetions: } 115 i 1. Ef^fer value direcUy.. or W , 2. CatCutat's by fiittng tn grey { 002 Vailable* SI Source Tliteliy^e$amSatZqne*j 15 }(#} Source Zones: „ , . ^ IConc,{mfl/ir cellsbelovi. {Torestore formutas, hit biMon betoW}^^^^^ Data used direcUy m model Value cakuikted by model. (Q&n't enter any data}. Vertical Plane Source Look at Plume Cross-Section and Input Concentrations & Widths for Zones 1, 2, and 3 jnsi R^saot Sfliubte ft/jass] In gggrpB NAPt.|. Soil _ _ _ 77 FJELD DATA FOR COMPARISON Concentratioft (rngll) Dist. from Source (ft) I B S ». CHOOSE TYPE OF OUTPUT TO SEE; \ RUN 1 ; CENTERLINE I Vi^w of Plume Looking Down Qb90rved Centedfne Concentrations at Monitoring Weth If No Data Leave Blank or Enter "0" RUN ARRAY Help fRecalculate This K. Sheet View Output \. View Output 1 Paste Example Dataset Restore Formulas for Vs, Dispersivities, R, lambda, other Golder Associates Novemi ifBoo I G ^ B 7 FIG( Transient Bioscreen AnaJy?!^ Chloroform (FPP Area) 2000 Data Match ^ • 6 0 1 6 CHLOROFORM CONCENTRATION ALONG PLUME CENTERLINE (mg/L at Z=0) Distance from Source (ft) TYPE OF MODEL No Degradation 1st Order Decay Inst. Reaction ' Field Data from Site 0 0.166 0.166 0.166 10 0.224 0.127 0.224 0.100 20 0.332 0.102 0.332 0.020 30 0.506 0.088 0.506 40 0.758 0.079 0.758 : 50 0.820 0.054 0.820 60 0.557 0.025 0.557 70 0.354 0.011 0.354 80 0.209 0.005 0.209 90 0.114 0.002 0.114 100 0.057 0.001 0.057 E c u B O U 0.90 0.80 0.70 0.60 0.50 0.40 0.30 0.20 0.10 0.00 Calculate Animation •1st Order Decay Instantaneous Reaction m • No Degradation Field Data from Site 1 ..- • , • ' ' ' • ' ".•. 20 40 60 Distance From Source (ft) 80 100 120 Time: 2.0 Years Return to Input jRecalculate This Sheet o o H u> G:/003-6016/Golder/FS Report/Draft2/ Gchlor98-00.xls/Centerline Output Golder Associates Noven^^EoOO Transient Bioscreen Ana^Br- Chloroform (FPP Area) Time to Compliance Simulation ^ B ? 0 1 6 CHLOROFORM CONCENTRATION ALONG PLDME CENTERLINE (mg/L at Z=0) TYPE OF MODEL No Degradation 1st Order Decay • ; Inst. Reaction • Prelim. Remed. Goal 0 0 075 0.075 0.075 0 080 L 10 0.106 _ 0.057 0.106 0 080 20 0.161 0.046 0.161 0.080 30 _0 257 0.040 0.257 0 080 Distance from Source (ft) 40 50 0 411 ' 0.643 0.036 0.411 0 080 0.033 0.643 0.080 : • ' 6 0 , - / 0.808 0.026 0.808 0.080 , - 'X , "'"';7o.'- 0.582 0.012 0.582 0.080 - , " • . ' 80 - r 0 397 _ 0.006 0.397 0.080 90 0 256 0.003 0.256 0.080 100 0 155 0.001 0.155 0 080 B O B u B O U E 0.20 0.15 0.10 0 05 0.00 Calculate Animation '1st Order Decay Instantaneous Reaction., IJ'-'No Degradation •.•J,- PRG 20 40 60 Distance From Source (ft) 80 100 120 Time: 2.5 Years Return to Input Recalculate This Sheet G:/003-6016/Golder/FSReport/Draft2/ Fig38.xls/Centerline Output Golder Associates 00 lo Noven^HoOO F I G ^ p 3 9 Chloroform Pulse Simulation Data Input 6016 BroSCREEN Natural Attenuation Decision Support System Air Force Cefit0rfor£nvim}menta} BxceHence 1. HYDROQEOLOOY Seepage Velocity* or Hydf au8e Conductivity Hydf auiic Gradient Porosity Z. DISPERSION Un^tfirfdinal DispersjvJty* Transverse Dispersivity* VerlicaJ Di^ersivity* or Estimated Phime length i . ADSORPfidf^ Retardaliof^ factor* or Soil Bulk Denwty Partition Coefffctent FractionOrgantcCarfeon Vs K afphay Lp R rho Koc foe 4, BIOOEGRADATJON 1st Order Decay Coeff* iambtta or Solute Half-life f-ha/f orJnstantanedUs ReaCttxth Modet Delta Oxygen* DO Delta Nitrate* N03 Observed F^rrwsf ron* F B 2 + DeJta Sulfate* S04 0|)3erved Methajje* CH4 36.6 TfT 5.9E-04 0.012 0.2 (cm'sec) (m) '0 104 1.0 0.0 w I ISO (ff) (fi) (ft) (fi) \(y^^<-} (mg/L) (nig/L) (m^/L) (mg/L} (mg/L) Ver&kfft 1.4 "iToENERAL Modeled ^ e a length* Modeled Anea Width* Simulation Time* Island Chemical chloroform pulse Run N^me 200 100 . _ _ „ . . . . . (ft) f (S) W (yr) + Data inputiastruciioas'. PTis' [ 0 02 6. SOURCE DATA Source Thicknesa in Sat.Zom* Source Zones: Variable* m 1. Bnter value directly - or 2. Calculate by Mtng in grey cells below. {To restore formiilas, hit btMqnbefow), Data used directly in model, "value cahittated by model (Qm't enf&r m y data). Width* (ft) 12 19 5 Cone, fmfl/U* 0.1 0.5 4 " 1 Vertical Plane Source Look at Plume Cross-Section and Input Concentrations & Widths for Zones 1, 2, and 3 Source Haffllfe (see Help); In&t, React ^ ^ ' ' j ^ Is-tOrderj Soluble Mass] jnScjMrpB NAPi, Spit _ 7. FJEUD DAfA FOR CO CAPARISON Concentration (mg/l)l i Dist from Sottrc^ ( l t ] i | K I &. CHOOSE TYPE OF OUTPUT TO SEE; f RUN View of Plume Looking Down Observ&d Centerline^ Concentrations at Monttonng Wells tfNo Data Leave Blank or Writer "Q" 04 100 120 140 160 180 200 CENTERLINE v.... r" L. RUN ARRAY fe/i "N /", / " • • View Output ^ 1^ View Output j Paste Example Dataset Recalculate This Sheet •" " S j ^,.. Restore Formulas for Vs, Dispersivities, R, lambda, other j ..J o o M Ui U) G:\PROJECTS\003-6016\Golder\Feas.Study(FS)\FS Report \Draft2\Bioscreen\Gchlor_pulse.xls/lnput Golder Associates |40 Chloroform f^fSe Simulation 3-year Travel Time CHLOROFORM CONCENTRATION ALONG PLO'ME CENTERLINE (ing/L at Z=0) Distance from Source (ft) TYPE OF MODEL No Degradation 1st Order Decay Inst. Reaction Field Data fmm Site 0 0.084 _ 0.084 0.084 0.100 20 0.092 0.075 0.092 0.020 40 0.195 0.132 0.195 60 0.401 0.235 0.401 80 0.388 0.204 0.388 100 0.192 0.093 0,192 [ 120 0.077 0.035 0.077 140 0.025 0.011 0.025 160 _ 0.006_ 0.003 0.006 180 0.001 0.001 0.001 0.040 200 0.000 0.000 0.000 '1st Order Decay Instantaneous Reaction No Degradation :s Field Data from Site 50 100 Distance From Source (ft) 150 Calculate Animation Time: 3.0 Years Return to Input 200 Recalculate This Sheet^ 250 1 ^ o o G:\PROJECTS\003-6016\Golder\Feas.Study(FS)\FS Report\ Draft2\Bioscreen\Gchlor_pulse.xls/Centerline Output Golder Associates Novel 000 F I G ^ V 4 1 Chloroform Ptnse Simulation 8-year Travel Time with 40 ppb at MW-11 - I G ^ W 4 'm Ptnse J ^P-6016 CHLOROFORivi CONCENTRApON ALONG FLUME CENTERLJJSE(mg/L at Z- Distance from Source (ft) TYPE OF MODEL No Degradation 1st Order Decay InsL Reaction ' ••-, Field Data from Site 0 OOOO 0.000 0.000 0.100 ,..20 oooo 0.000 0.000 0 020 . . .40 oooo 0.000 0.000 ... 60 0 001 0.000 0.001 - 80„ 0 003 0.001 0.003 100" 0 008 0.002 0.008 120,:; 0 021 0.005 0.021 140/ ._ 0055 0.011 , 0.055 -. 160,-,;., _ 0 137 1 0.022 0.137 1 8 0 . ; 0323 0.046 0.323 0.040 • 200 ; 0 287 0.036 0.287 s s •o 0.35 0.30 0.25 0.20 0.15 0.10 0.05 0.00 0 Calculate Animation • • • • 1st Order Decay • i Instantaneous Reaction No Degrada - r ; • • H . ion MW-11 -i :: Field Data from Site 1 , . 50 100 150 Distance From Source (ft) 200 250 Time: 8.0 Years Return to j Input J Recalculate This Sheet; o o M Ui Ol G.\PROJECTS\003-6016\Golder\Feas.Stucly(FS)\FSReport\ Draft2\Bloscreen\Fig41 .xls/Centerline Output Golder Associates I APPENDIX A DETAILED COST INFORMATION i» ^ 400140 I June 2001 P V Table A-1 Cost Worksheet Virgin Island Chemical Site SVE/Air Sparging Activity ESTIMATED DIRECT CAPITAL COSTS Air Sparqe/SVE Wells & Accessories Air Injection Wells (depth 50', 1" diameter, 2' screen) Pressure Gauge Flow Meter Body Check Valve Provision and Installation of all FittingsA/alvesAA/ell Head Assemblies (15% of Well Costs) Protective Enclosure for Air Injection Wells SVE Well Modifications " ' Below Ground Conveyance System Excavate Trench (1'xl') Backfill forTrench{rx1') Geotextile to line Trench Piping (assume 2" PVC, Schedule 40, Connection Piping) 2" PVC, 90 Degree Elbow Misc. conveyance pipe fittings -15% of pipe and fitfings cost It/lechanical & Controls Mechanical & Electrical Installation - 40% of Well & Accessory Cost System Checkout & Cut off to Old System (20% Well & Accessory Cost) Blowers & Treatment Blower (30.0 HP, 580 SCFM Vapor Extraction) Air Compressor for Air Sparging General Mobilization/Demobilization for Drilling ''' TOTAL DIRECT CAPITAL COST ESTIMATED INDIRECT CAPITAL COSTS Gen. Engineering Services (15%) Permitting/Regulatory Coordination (3%) Implement Health & Safety Plan (20%) Construction Oversite/QA/QC (20%) Contingency (30%) O & M COSTS Soil Vaoor Extraction/Air Sparqinq: O&Mcostforl year(10%) Mobilization/Demobilization Analytical Testing - soil vapor, off-gas Trailer Utility Services (Gas/Electric) Unit Costs $3,888 $120 $844 $192 $756.61 $296 $625 $16.56 $25 $0.26 $3.89 $24.33 $63.43 $8,816.47 $2,075.25 $8,858 $14,184 $50,000 $107,408 $21,482 $143,211 $143,211 $214,817 $5,665.60 $10,000 $7,500 $3,210 $42,000 Units per well per well per well per well per well per well per well CY CY SF LF Each % % % Each Lump sum Lump Sum % % % % % Year Year Year Year Year Quantity 3 3 3 3 3 3 6 3 3 270 90 3 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 Estimated Cost $11,665 $359 $2,531 $577 $2,270 $889 $3,750 $50 $75 $71 $350 $73 $63 $8,816 $2,075 $8,858 $14,184 $50,000 $716,056 $107,408 $21,482 $143,211 $143,211 $214,817 $5,666 $10,000 $7,500 $3,210 $42,000 Notes and Assumptions: 1. Assume all drilling will occur uncJer one mobilization and demobilization fee, 2. Cost estimate sources include Means (with 25% additional cost due to remote location), previous Golder projects, and vendor quotes G:/6016/FSRepoil/FSJune2001/TBL-A1&2.Kls/A-l air sparging Golder Associates 400141 I June 2001 003-6016 Table A-2 Cost Worksheet Virgin Island Chemical Site Monitored Natural Attenuation i» Activity ESTIIVIATED DIRECT CAPITAL COSTS Monitored Natural Attenuation Monitoring Wells General Mobilization/Demobilization for Drilling''' ESTIIVIATED INDIRECT CAPITAL COSTS Gen. Engineering Sen/ices (15%) Permitting/Regulatory Coordination (3%) Implement Health & Safety Plan (20%) Construction Oversite/QA/QC (20%) Contingency (30%) Monitored Natural Attenuation Mobilization/Demobilization IDW Disposal Monitored Natural Attenuation -Annual Samplinq Annual Sampling - unit cost one round of sampling -Year 1, quarterly: Present Wortti (1 yr @ 7%) -Years 2-3, semi-annually, Present Worth (2 yrs @ 7%) -Years 4-15, annually, Present Worth (12 yrs @ 7%) PRESENT WORTH Annual Sampling Monitored Natural Attenuation 0 & M COSTS One Time - Yr Seven Well Rehabilitation Unit Costs $2,350 $50,000 $99,262.79 $19,852.56 $132,350.38 $132,350.38 $198,525.57 $10,000 $300 $1,913 $28,688 $28,688 $28,688 Units Each Lump Sum % % % % % Year Well/Year Well Round Round Round $800 Well Quantity 5 1 1 15 15 4 2 1 15 Estimated Cost $11,752 $50,000 $99,263 $19,853 $132,350 $132,350 $198,526 $10,000 $4,500 $107,000 $97,000 $186,000 $390,000 $12,000 Notes and Assumptions: 1. Assume all drilling will occur under one mobilization and demobilization fee. ^ G:/FSReport/FSJune2001/TBL-AlS2.xls/A.2 mon natural alien Golder Associates 400142 I Table A-3 Cost Estimate Focused Feasibility Study Pump & Treat (Extraction from Shallow Aquifer, Air Stripping, and Discharge to River Gut) l» w Activity ESTIMATED DIRECT CAPITAL COSTS Mobil ization/DelVlobilization For Drilling Wells Extraction Well Submersible p u m p plus spares Pitless adapter Pressure Transducer and Indicating Tramsitter plus spares Flow Meter Leak Detection System Monitoring Well Electrical Electrical vaults - 3' by 3' Mechanical / electrical installation Control panel Monitoring panel Control wiring and 1" to control Panel Electrical wiring in 7 ' conduit to Monitoring panel conduit affixtures 25% cost of conduits Power distribution {new breal<er and service) N e w plione service inc. autodialer Convevance 1" Polypropiene Pipe Misc. conveyance pipe fittings • 15% of pipe and fittings cost Trencti excavation (1 ft wide by 1 ft higti) Place and spread excavated soil Clean baci<fill, compacted in trench (pea gravel) Geotextile used in trench as separation Treatment Setup 10,000 gallon holding tanit Steel Dil<e for tanl< Misc. holding tank fittings (30% of tank cost) Air Stripper with Blower (no air control) Discharge Permits/Applications TOTAL DIRECT CAPITAL COST O & M COSTS Mobilization/Demobilization Pavement Inspection/Repairs G W Extraction Well Maintenance and System Balancing Monitoring - G W sampling, off-gas sampling, water levels, flow rates Air Stripper & Blower Maintenance Treatment/Annual Discharge Fees Permits Utilities (electric, phone) Paint tank/Repairs Startup Systems (5% equipment cost) Unit Costs $50,000 $6,250 $2,000 $2,065 $1,400 $675 $10 $7,000 $4,675 $15,000 $1,000 $120 $8.69 $8,688 $477.83 $10,000 $5,000 $4.46 $167.34 $16.56 $9.00 $25.00 $0.26 $8,899 $9,769 $2,669.63 $15,000 $10,000 Units Lump Sum Each Each Each Each ^ Each LF Each Each Lump Sum Each Each LF LF Lump Sum Lump Sum Lump Sum LF Lump Sum cy cy cy St Eacti Eacli % Each Lump Sum $10,000 $5,000 $22,000 $75,000 $10,000 $0 $1,000 $5,000 $1,667 $8,800 Year Year Year Year Year Year Year Year year Each Quantity 1 2 4 2 4 2 250 2 1 1 1 1 20 200 1 1 1 250 1 2625 2625 2625 760 1 1 1 1 1 Estimated Cost $50,000 $12,500 $8,000 $4,130 $5,500 $1,350 $2,500 $14,000 $4,575 $15,000 $1,000 $120 $174 $1,738 $478 $10,000 $5,000 $1,116 $167 $43,470 $23,625 $65,625 $195 $8,899 $9,769 $2,570 $15,000 $10,000 $316,799 $10,000 $5,000 $22,000 $75,000 $10,000 $0 $1,000 $5,000 $1,667 $8,800 Notes and Assumptions: 1. Assume al! drilling will occur under one mob/demob fee. 2. Cost estimate sources include Means (with 25% additional cost due to remote location), previous Golder projects, and vendor quotes G:\PROJECTS\OO3-6016\GOLDER\FEAS.STUDY(FS}\PUMP8:03PMRT\P8:03PMCOST,XLS 400143 I APPENDIX B EPA PRESUMPTIVE REMEDY GUIDANCE i» W 400144 S-EPA Var United States Environmental Protection Agency Office of Direaive; 9355.0-48FS Solid Waste and EPA 54C>-F-93-048 Emergency Response PB 93-963346 September 1993 Presumptive Remedies: Site Characterization and Technology Selection For CERCLA Sites With Volatile Organic Compounds In Soils Office of Emergency and Remedial Response Hazardous Site Control Division 5203G Quick Reference Fact Sheet P Since Superfund's inception in 1980, tbe retoedial and removal programs have found that certain categories of sites have similar characteristics, such as types of contaminants present types of disposal practices, or bow environmental media are affected. Based on infonnation acquired from evaluating and cleaning up these sites, the Superfund program is undertaking an initiative to develop presumptive remedies to accelerate future cleanups ai these types of sites. The presumptive remedy approach is one tool of acceleradon within the Superfund Accelerated Cleanup Model (SA.CM). Presumptive remedies are preferred technologies for common categories of sites, based on historical patterns of remedy selecdon and EPA's scientific and engineering evaluadon of performance data on technology implementadon. The objecnve of the presumptive remedies initiarive is to use the program's past experience to streamline site investigation and speed up selection of cleanup actions. Over time presumptive remedies are expected to ensure consistency in remedy selection and reduce the cost and time required to clean up similar types of sites. Presumptive remedies are expected to be used at all appropriate sites except under unusual site-specific circumstances. This directive identifies the presumptive remedies for Comprehensive Eoviroimiental Response, Con^)ensation, and Liability Act (CERCLA) sites with soils contaminated by volatile organic compounds (VOCs). In addition, EPA is developing guidance on presumptive remedies for wood treatment, municipal landfill, PCB, grain storage, coal gasification, and contaminated ground-water sites. EPA has also developed a directive entiUed Presumptive Remedies: Policy and Procedures, (Directive 9355.0-47FS) which outlines and addresses tbe issues common to all presumptive remedies (e.g., role of innovative technologies, consistency with the NCP, State, community involvement). W PURPOSE The purpose of this directive is to provide guidance on selecting a presumptive remedy at sites with soils contaminated with VOCs. Spec^cally this guidance: • Presents the presumptive remedies for this site type; • Describes the prer.umptive remedy process in terms of site characterization aod technology screening steps: and • Outlines the dau required to select these presumptive remedies. Since a presumptive remedy is a technology that EPA believes, based upon its past experience, generally will be the most appropriate remedy for a specified type of site, the presumptive remedy approach will accelerate site-specific analysis of remedies by focusing the feasibility study efforts. Where several presumptive remedies are identified, EPA believes that all deserve substanrial consideration before unlizing the presumptive remedy approach. EPA penonnel should review the directive entitled Presumptive Remedies: Policy and Procedures (Directive 9355.0-47FS) for general information on tbe presumptive remedy process. Soil vapor extraction (SVE), thermal desorption, and incineration are the presumptive remedies for Superfund sites with VOC-contaminated soil assoming the site characteristics meet certain criteria. Table I provides a brief description of each ofthese presumptive remedies. The decision to establish these technologies as presumptive remedies for this site type is based on EPA's collective knowledge about site investigation and remedy selection for VOC-contaminated soils. in 1-1 o o NOV 3.J993 TABLE 1 Presumptive Remedies for VOCs in Soil Soil Vapor Extraction • Soil vapor extraction (SVE) is an in-srtu or ex-situ process wtiich physically removes contaminants from vadose zone soils by inducing air flow through the soil matrix. The flowing air strips volatile compounds from the solids and carries them to extraction wells. The recovered vapors may require further treatment In-situ SVE is the primary focus of this document. Thermal Desorption •Thennal desorption is an ex- situ process that uses direct or indirect heat exchange to vaporize organic contaminants from soil, sediment sludge orother solid and semisolid matrices. The vapors are then condensed or otherwise collected for further treatment incineration - Incineration is an ex-situ engineered process that employs thermal decomposition via oxidation at temperatures usually greaterthan 900 "C to destroy the organic fraction of the waste. The major difference between thermal desorption and incineration is that incineration oxidizes organic compounds, thereby destroying the hazardous material. Thermal desorption volatilizes contaminants, then concentratesthem. Thermal desorption reduces the volume of contamination, buttheconcentrated waste stream st1i requires treatment. Disposal or treatment of residual waste stream, ash, and concentrated VOC effluent is not covered by this directive. Options sijch as off-site disposal/regeneration or reuse should be considered. including field experience from tbe Superfiind, Resource Conservation and Recovery Act (RCRA), aod Underground Storage Tank (UST) programs. In addition, EPA conducted an analysis of FY86 to FY91 Records of Decision (RODs) for sites where VOC contamination drove remedy selection. Tbe results of this analysis, which are provided in Appendix A, demonstrate that these three technologies represent over 90% of the remedies selected in the RODs analyzed. USE OF DOCUMENT This directive is primarily intended for use by Superfiind site managers. However, site managers in other programs (such as RCRA corrective action, die UST program. States), and the private sector, may also use this directive. This directive is not a "stand alone" document To ensure a fiill understanding of VOC site characterization and remedy selection, site managers should refer to all documents cited in the directive. For assistance in understanding complex site conditions, an experienced site maiuger, the i^esutnptive remedy expen t^am the Superfund Technical Assistance aiKl Response Team (START) team, or the Environmental Response Team should be consulted. ANTICIPATED BENEFITS OF PRESUMPTIVE REMEDIES Use of this directive will reduce cost aixl nm^ in remedy selection at VOC sites in the following ways: 1. The directive facilitates identification of the ptesuziKd or likely remedial options eariy in the investigation process, hence allowing for amore focused collection of data during the remedial investigation (RI) or removal site evaluation. In addition, knowledge of the presumptive remedy may facilitate collection of some remedial design data befwe tbe ROD or action memo, thereby allowing the action to proceed more quickly after signamre of tbe decision document 2. This directive eliminates tbe need for the initial step of identifying and screening a variety of alternatives during the Feasibility Smdy. AdditionaUy, it will reduce the number of technologies identified and analyzed in the EE/CA. The National Oil and Hazardous Substances Pollution Contingency Plan (NCP) (Section 300.430(e)(1)) states that "the lead agency shall include an altematives screening step, when needed (emphasis added) to select a reasonable number of alternatives f a det^uled analysis." EPA's analysis of feasibility sudies for V(DC-contazninated soil sites (see Appendix A) found that certain technologies are routinely screened out based on e^ectiveness, implementability, or excessive costs, consistent with NCP Section 300.430(e)(7). Accordingly, EPA has determined that when using presumptive remedies at VOC-contaminated sites, site-specific identification and screening of altematives is not necessary. However, this directive and supporting documentation (see Teasibility Study Analysis for CERCLA Sites witfi Volatile Organic Compounds in Soils") should be included in the Administrative Record for all sites that use the presumptive reiiiedy(ies) to document the basis for eliminating the "site-specific identiflcation and I <l ^ 400146 i I I p w TABLE 2 Typical VOCs Addressed by this Directive Haloqenated Volatile Organics Carbon Tetrachloride Chlorobenzene Chloroethane Chloroform 1.1-Dichloroethane 1,1-Dichloroethylene 1,2-Dichlorobenzene 1,2-Dichloroethane 1,2-Dichloroethylene 1.2-Dichloropropane 1.4-Dichlorot)enzene 1,1,1-Trichloroethane 1,1,2-Trichloroethane 1,1,2,2-Tetrachloroethane Ethylene Dibromide Methylene Chloride Tetrachloroethyiene Trichloroethylene Vinyl Chloride Non-Halogenated Volatile Organics Ketones/Furans Acetone Methyl Ethyl Ketone Methyl Isobutyl Ketone Aromatics Benzene Ethyl Benzene Styrene Toluene m-Xylene o-Xylene p-Xylene Note: Other compounds that have physical/chemical characteristics similar to the compounds listed may also be addressed by the presumptive remedy process. screening of technologies" section. In addition, other supporting materials (e.g., FS reports included in the analysis, technical reports) will be made available at EPA Headquarters and are available for inclusion in the Administrative Record if needed This directive streamlines the detailed analysis portion of the FS.J^emedial altematives developed for a site must be evaluated against the nine criteria (required under NCP Section 300.430(e)(9)). Under this presumptive remedy approach, the detailed analysis can be limited to the three presumptive remedies (in addition to the no-action altemative), thereby streamlining that portion of the FS. Appendix B provides a generic evaluation of the presumptive remedies for seven of the nine criteria. This evaluation may serve as a basis for each detailed analysis conducted under the presumptive remedy process and should be augmented as needed, to address site- specific conditions. One ofthese presumptive remedies is expected to be used for all V(X) sites except under tmusual circumstances. Such circumstances may include unusual site soil characteristics, demonstration of significant advantages of alternate (or other innovative) technologies over the presumptive remedies, or extraordinary community and state concems. If such circumstances are encountered, additional analyses may be necessary or a more conventional detailed RI/FS may be performed. PRESUMPTIVE REMEDIES PROCESS This section and the accompanying diagram (Figure 1) describe the sequence of steps involved in tbe presumptive remedy process (site characterization and technology selection) for sites containing soil contaminated with VOCs. While the process is not mandatory, EPA believes that following the steps outlined below will expedite the clean-up process for this category of sites. SVE is the primary presumptive remedy. SVE has been selected most firequentiy to address VC)C contamination at Superfund sites and initial performance data indicate that it effectively treats waste in place at a relatively low cost In cases where SVE will not work or where there is very highly concentrated contamination, thermal desorption may be the more appropriate response technology. In a limited number of situations, incineration may be more appropriate. The numbered paragraphs below correspond to the numbered steps in Figure 1 and provide a detailed discussion of each step. 1. Are VOCs Present in the Soil? The first step is to determine whetiier VCXIs are the major contaminam present in soil at the site. Table 2 lists die VOCs that are amenable to tbe presumptive remedies outlined in tills directive. If VOCs are present at levels of concem (see forthcoming guidance on soil screening levels), then tbe presumptive remedies outlined in this directive may be applicable. However, if it is confirmed (at this point or at any later point during the presumptive remedy prtxess) that there are no VOCs present in the soil, then this directive is cot applicable for use in technology selection at the site. 400147 I FIGURE 1 Decision Tree for investigating and Selecting a Remedy at Solvent Sites ^ ® Initiate •arty PRP, State, and community invoivtcnent if presumptive remeijy approach is appropiiate. Assemble Administra- tive Record This fact sheet is not Review awanagss/ liniitaliar)sta6elor prtsumptive lemeites. SeeTaNsZ ^ i Ci>- © Q Conduct iime<Tiiical (emovil aoioa < neoessarir. See'Practical ConsiderakxB' (AdiitimuJ TactiwiagiesI NoRirtier Action PiDceed eift tKtmiagy andmiew i f i i I I I ConsidBQtions* s«tiort «i PtQCBBdwrtfi ROD or Action M#(no tno w 400148 I w p 3. w Most likely, this analysis will occur during scoping of the RLFS or EE/CA. However, there may be only limited information available at that time about the site. Therefore, whatever infwmation is available should be used to determine whether VCXZs are present or suspeaed in the soil based on prior use. Chemical use at a site can be ascertained fitjm a number of sources such as facility records, previous sampling efforts by local or State agencies or through Information Request letters. Are Non-VOC Contaminants Present That Preclude the Use of Presumptive Remedies? In addition to determining whether VCX^ are present in tbe soil, it is also necessary to identify other non-VOC contaminants, if any, present in the soil. The site characterization and technology selection procedures oudined in this directive are recommended for use primarily on soil containing VOCs only. See Table 2 for VOCs that are amenable to the presumptive remedies. For sites containing a mixmre of VOCs and other contaminants in soil, the presumptive remedies should be considered only if they can also be effective in removing the aon-VOC contaminants or combined with other, non-presumptive remedies in a treatment train, assuming the presumptive remedies do not exacerbate the problems presented by the noo- VOCs. For exanqjle, sites with VOCs and metals commingled in soil may be effectively remediated by employing SVE to remove V(Xs followed by fixation or solidification to address the metal contamination. In contrast, a VOC and polyaromatic hydrocarbons (PAHs) contaminant combination may be created more appropriately with a single biological oeatment scheme that would be effective for both the VOCs and PAHs. Note that sites containing mixtures of VCXIs and non-VOCs are varied, and for this reason, remedy selection may be more complicated than the fiamework presented in this directive; therefore, the presumptive remedy analysis may need to be supplemented or modi5ed on a site-specific basis. Initiate Eariy Community, State, and Potentially Responsible Party (PRP) Involvement. As early in the clean-up process as possible, EPA should notify the community. State, and any PRPs thatapresumptive remedy is being considered for the site. It is important for all stakeholders to understand completely how the presumptive remedy process vanes from the usual clean-up process and the benefits of using the presumptive remedies process. Early identification of State applicable or relevant and appropriate requirements (ARARs) also is a critical pan of this process. Because the presumption set forth in this directive is national in scope, it does not take into account State ARARs. For this reason. State ARARs relating to die presumptive remedies should be considered on a site-specific basis. Regions may want to supplement this directive by compiling the requirements of the States in their Regions that are likely to be associated with the use of the presumptive remedies and placing them in the admitustrative record for a site where presumptive remedies are being considered This directive along with the Teasibility Smdy Analysis for CERCIA Sites with Volatile Organic Compounds in Soils" should be included in the administrative record for tbe site if one of the presumptive remedies is proposed for aparticular VOC-contaminated site. Review Advantages/Limitations of the Presumptive Remedies. During initial site characterization. Table 3 should be reviewed to consider the advantages and limitations of the presumptive remedies. This information may be useful in preparing for and/or modifying the site characterization or altematives analysis process. The "Practical Considerations" section of this directive should also be reviewed at this time to ensure a comprehensive site characterization and remedy evaluation. Condua Site Charaaerization. Site characterization for sites using VOC presumptive remedies should be designed to: » Positively identity the site type (i.e., VOC site): • Obtaindatatodetermine whether the presumptive remedy is feasible for tbe site; « Focus (and possibly streamline) site characterization by collecting data to support the selection of presumptive remedy(ies) only (e.g., volume and cost information); and, o Collect some design data (Le., pilot studies to determine radius of influence and flow rates of SVE), tiiereby streamlining datacoUection during the remedial design stage. Table 4 lists the dau that are required for characterization of sites with soil contaminated with VOCs. This table also includes the rationale for collecting these data and references for established collection methods. Note that bench-scale and pilot/ treatability studies should be performed whenever possible concurrent with site characterization todefine the parameters that will be important to designing tbe system. In areas with low organic content soil (e.g., alluvial basins), or where there are impediments to obtaining soil samples (e.g., under buildings), soil gas sampling 400149 is highly recommended as a site characterization techiuque. In addition, the use of soil gas sampling during implementation of SVE and confirmatory soil sampling afterward is less expensive than cc:; >iantiy installing new soil borings, especialh ji deep contamination. If incineration or thermal desorption is under serious consideration, bench-scale treatability smdies may be conducted especially if metals or other inorganic compounds are present Thermal desorption generally shoiUd be considered if concentrations of VOCs are less than S to 10 percent incineration may be appropriate if VOC concentrations exceed S to 10 percent Note that excavation and mixing of soil can produce a desorber input of less than 10 percent contaminant concentration and ;dlow thermal desorption to be chosen. Additionally, the feasibility of excavation should be determined by evaluating surfeux conditions and depth of contaminants as well as the potential for any air emissions associated with the excavation. Test digs should be monitored closely to assure protection of the public and tbe environment. It is important to note that during the site- characterization, the volume and concentration of waste constimting the principal threats at the site should be identified. The NCP (Section 300.430(a)(l)(iii)(A)andAGui<i«to/>nncipa/77ifear and Low Level Threat Wastes, SuperfundPublication: 9380.3-O6FS, November 1991, define principal threats as source materials, including liquids, that are highly toxic or highly mobile wastes which generally cannot be reliably contained or would present a significant risk to human health and or environment should exposure occur. In accordance with NCP expectations, waste constimting "principal threats" posed by a site generally are expected to be treated The site manager is encouraged to characterize the site in terms of principal and low-level threat areas to determine materials to be targeted for treatment and containment 6. Identify Potential ARARs, To Be Considered (TBCs), andPreliminaryRemediationCoals(PRGs). Potential Federal and State ARARs and pertinent TBCs information should be identified on a ciiemical-, location-, and action-specific basis concurrent with site characterization. For a more detailed ARARs discussion, refer to tbe various ARARs fact sheets. (Sec Compendium of CERCLA ARARs Faasheets and Directives, EPA Publication 9347.3-15, October 1991). At this step, PRGs should also be identified (NCP Section 300.430(eX2)(c)). Note that different health risk-based PRGs are often set for soils, depending on depth. Shallow soil levels are usually based both on direct contact exposure aod protection of ground water, while levels for deeper soils are generally based only on mass ffansport modeling of effects on ground water. Ecological effects may also be important to consider in setting PRGs. 7. ConduaTime-CriticalRemovalAction(ifnecessary). During initial site characterization, data will be gathered to determine whether atime-critical removal action will be needed and to determine whether the contaminants present are amenable to the presumptive remedies. Time-critical removal actions, such as drum removal or actions addressing highly contaminaied(typical]y small volumes)of soil, should be conducted in accordance with current guidance aod regulations. The decision to take a time-critical removal action may be made by the Regional Decision Team (RDT) or if time does not permit by an On- Scene Coordinator (OSC) or a Remedial Projea Manager (RPM) in consultation with an OSC. 8. IsThereaThreatPosedby the Site? A risk assessment must be conducted to determine if a sufficient health or environmental threat exists to warrant a removal or remedial action. (fLefer to Risk Assessment Guidance for Superfund, Volumes I and II. EPA/540/1-89/002 andEPA/540/l-89AX}l). Where it is determined that such a threat exists, site-specific exposure data can be used to modify the PRGs identified in Step 6 (NCP . Section 300.430(eX2)(i)). If it is determined that such a threat does not exist no further action at the site will be required. 9. Proceed With Technology Assessment and Review 'Practical Considerations" seaion. If the analysis described in step 8 confirms that the contaminants are a threat to human health and/or the environment a proposed remedy should then be identified, If this project is a remedial action, a detailed analysis using the nine criteria will be required under NCP Section 300.430(e)(9)) to justify tbe selection of remedy decision. Appendix B provides an analysis of SVE. thermal desorption, and incineration against seven of tbe nine selection criteria. In addition to the seven criteria discussed in Appendix B, community, and State acceptance must also be evaluated Ifa non- time critical removal action is planned, tbe streamlined analysis described in the EE/CA guidance will be required that uses the duee criteria of effectiveness, implementability, and cost During tbe technology assessment the factors listed in the 'Practical Considerations" section of this directive should be reviewed to ensure a comprehensive evaluation of altematives. I «l ^ 400150 1 I I I I I I I P I I I I I I % II 10. Does the Pilot /Treatability Study Indicate that SVE is Feasible? SVEistheprimarypresumptiveremedy. Pilot/treatability smdy testing of SVE should be conducted prior to final remedy selection. Such testing will provide information on the rate of removal of contaminants. EPA/540/2-91/091A cited in the References section of this directive provides guidance on conducting the pilot/treatability study. Removal efficiencies and treatment effectiveness must be carefully considered alongside die PRGs identified in die FS to estimate tbe potential for successful remedial action using SVE. 11. Is Thermal Desorption Feasible? If SVE will not be sufficientiy effective in achieving PRGs due to low permeability, lithology or insufficient removal of contamination during tbe pilot study, thermal desorption should be considered as the primary ex- sini presumptive remedy. Thermal desorption technologies cover a variety of vendors and processes. However, ample data are available to substantiate remedy selection of thermal desorption for soil contaminated solely with VOCs. 12. Is Incineration Feasible? If contaminant concentrations and bench-scale testing indicate- thermal desorption will not achieve desired PRG levels, incineration is the second ex-siu presumptive remedy. If incineration is planned and a substantial number of inorganic contaminants are expected to be present based on site characterization data, materials handling problems, or slagging problems are likely. If none of the diree presumptive remedies is considered to be feasible at a particular site, it will be necessary to consider other technologies. (For more information, refer to the Practical Considerations section below.) 13. Select Remedy for Remedial/Removal Action. Atttus point there should be enough data to identify a preferred remedy in the proposed plan and disoibute the plan for public comment Once the remedy has been selected in tbe ROD, the user can proceed to do a limited design which relies largely on the substantial amount of design-related data collected during the RL Tbe exten'. of additional or supplemental data required will be determined on a site-specific basis. Practical Considerations The following faaors should be considered prior to taking any remedial action. Enforcement: This directive applies to fiind-lead sites as well as to sites where a PRP is conducting the investigation and/or response action. In tbe event that there is an ongoing PRP-lead RI/FS, the scope of work may be amended to reflect the presumptive remedy approach to site characterization and remedy selection. The potential savings in time and money to be gained by using the presumptive remedy approach are expected to outweigh the burden of modifying the scope of work in tnany cases. Initial Site Actions: If the VOC material is SQ\L in original, intact containers, it may be returned to the manufacturer (if tbe manufacturer is willing to accept these contair^rs), assuming this response is a cost-effective and feasible action as opposed to treating the material. Reuse of material (i.e., process liquids and relocation of equipment to other permitted facilities) should also be considered. Further.phaseseparationshouldbeconducted and recycling considered depending on the purity of the recovered phase or for any existing liquids that are high enough in concentration. Refer to Appendix C for alist of the currentiy recognized waste exchanges. Site Characterization: Site characterization should proceed as a single, multi-media activity whenever possible. Field screening methods should be integrated into tbe sampling and analysis plan in order to accelerate information gathering. Data quality must refiea the ultimate use of the information. Ground Water: Tbe decision maker should consider tte ground-water strategy for the site since soil clean-up levels are often set to protect ground-water quality. Therefore, ground-water clean-up levels may have adirea impaa on the selected clean-up levels for soil. (See forthcoming guidance on Soil Screening Levels and the directive entitied Presumptive Remedies: Remedial Strategy and Treatment Technologies for CERCLA Sites with Contaminated Ground Water.) It should be noted that of the VCX^-type contaminants, listed in Table 2, the balogeoated volatiles are dense nonaqueous phase liquids (dense NAPLs or DNAPLs) and many of the others are light NAPLs (LNAPLs) in their pure liquid form. If LN APLs are present, it may be possible to address tiiem by lowering the water table, removing free product (if present), and applying SVE. To address DNAPLs contamination, refer to tbe above mentioned ground-water guidance. Management of Different Soils: A siniation may arise where highly contaminated shallow material cannot be addressed by SVE. The action to address this contamination may differ from the rest of the soil contamination and will most likely involve incineration or thermal desorptioiL If it is suspected that soil contamination existing at greater depths will also be treated in tills manner, then the excavated shaUow material should be staged and stored in order to treat it with the deep material Another situation may arise where V0(3s are mixed with metals, and none of the presumptive remedies can address both sets of contaminants. The action to address this siniation may consist of a treatment train where VCXls are 400151 addressed through SVE or thermal desorption and the metals are addressed through fixation. Finally, the site manager should be aware of situations where a mixture of principal aod low-level threat wastes call for the use of treatment (i.e.. SVE or thermal treamient) of principal threat waste and containment (cs^ing) of low-level contamination. (See A Guide to Principal Threat and Low-Level Wastes in Reference Section). OfT-Site Disposal: In general, it may not be cost-effective to ship quantities of contaminated soil in excess of 5,000 cubic yards for off-site disposal. For this reason, preoeatment of soil and water may be required prior to shipment or discharge to another treatment facility. Capping: Capping alone is not recommended to control the migration of VOCs. However, capping can improve the effectiveness of SVE by decreasing the rate of infiltration of residual VCXs tlurougb the vadose zone into the ground water as well as possibly increasing the radius of influence and preventing "shon circuiting" of air pathways in the vicinity of the extraction well. C^>ping can also be used to address non-principal threat waste unless it is more cost-effective to treat this waste along with more highly contaminated materials. Patents: SVEisapaiented technology. Royalty payments may be required under certain conditions of implementation. Attaiiunent of Remediation Goals: It should be noted that, like other in-sioi technologies, it is difficult to ascertain with confidence whether SVE will attain remediation goals until die action is actually iii^)lemented However, tbe lower cost and ease of SVE implementation will often weigh heavily in its favor, as long as protection of human health and lbt environment is ensured Additional Technologies: If for some reason none of the presumptive remedies is applicable to a particular site, the site manager is encouragwl to refer to EPA's forthcoming document entitied Contaminants and Remedial Options at Solvent Sites foradiscussicn of additional VOC treamient technologies. It should be noted that this comprehensive document which identifies additional VOCs and technologies, may be appropriate to consider on a site- specific basis. Thermal Treatment Technologies: Tbe site manager should refer to EPA's Draft Strategy for Combustion of Hazardous Waste (May 18,1993) when considering any thermal treatment technologies at a particular site. Conclusion For sites containing VOC-contaminated soil and appropriate soil characteristics, SVE is a relatively inexpensive and efficient technology. If material needs to be excavated, thermal desorption is preferred. In a few cases, incineration may be the most appropriate remedy - - for example, where SVE and thermal desorption will not meet clean-up criteria based on contaminam concentrations or composition. As remedies other than SVE, thermal desorption and incineration become more widely used in the fiiture, this directive may be modified to reflect these trends. For further assistance on presumptive remedy related activities consult the Regional Presumptive Reniedies contact ^ Notice: The policies set out in this document are Intended solely as guidance to the U.S. Environmental Protection Agency (EPA) personnel; they are not final EPA actions and do not constitute rulemaking. These policies are not intended, nor can they be relied upon, to create any rights enforceable t>y any party in litigation with the United States. EPA officials may decide to follow the guidance provided in this document or to act at variance with the guidance, based on an analysis of specific site circumstances. EPA also reserves the right to change this guidance at any time without public notice. % 4 400152 % TABLE 3 Comparison of Technologies for VOC Sites »o o o Ul Ui c -J3 O "E iD o n i > 1 c & To g .c ^ c o •X3 s 4> c G £3 PERFORMANCE^^* Can be as high as 99% removal of VOC contaminants but Is typically lower than other lechnologies with range 0185-99% 95-99% removal ol VOCs >99% removal ol VOCs ADVANTAGES • High level ol effectiveness in removing VOCs. • Relatively inexpensive. • Little site dlstutfoance; no excavation required. • Effective lor waste under buildings or other conslrucllon. . • All compounds that are listed on Table 2 are readily treated by thermal desorption. • Because ol lower IrealmenI temperatures and often lower oxygen levels, thermal desoibers should produce less nitrogen oxides and sulfur dioxide than Inclneralors. • Process can be peilonned onsite or offsite. t Lower temperatures produce fewer products ol kicomplele combustion (PICs). ' Capable of accepting a wide range ol media. • Processes can be performed onsite or offsite. * Metals can be concentrated in the residuals. LIMITATIONS * Soil that is tight or has high moisture conleni (>50%) has a reduced pemieabllity lo air, hindering Ihe operation of SVE. • Soil with a high degree of helerogeneily has highly variable penneabilities. resulting in uneven delivery of gas flow to the conlaminated regions, which In tum reduces removal rates by SVE. • Soil with high organic content or that is extremely dry has a high sorption capacity for VOCs, which results in reduced removal rates. • SVE may requite treating residual soil tailings, liquids, and spent aclivaled caibon. * Air emissions musi be controlled lo eliminate possible harm to the public and the environment. * SVE is not efleclive in the saturated zone. However, lowering the aquifer can expose more media to SVE (this may address concems regarding LNAPLs). * Requires excavation. If contaminalion is very deep or below Ihe water table, excavation may be difficult and expensive. • Mercury, if present, can be removed from soil by thermal desorption and hnpose additional freatment costs lor Ihe oHgas. * Soil containing high fractions of clay or silt may result in a high percentage ol particulate carry- over Irom Ihe desoiber Wo downstream IreatmenI devices. * Soil that contains constituents greater than 1 lo 2 Inches In diameter will require screening or cnishing lo prevent jamming the mechanical equipment. • Soil wHh a high moisture content (>30%) can result in low processing rates, high operating costs, and difficulty in materials handling * High or low pH wastes may corrode the metal components of Ihe system, requiring pretreatment. * Potential process residuals are treated solids, oversized debris, condensed contaminants and water, particulate control system solids, and contaminated aclivaled caibon. * Air pollution control system required. • Requires excavation. 11 conlamnalion is v e ^ deep or below the water table, excavation may be difficult and expensive. • Soil containing high fractions ol clay or sill may result in a hig^ percentage of particulate carry- over Irom Ihe Incinerator into downstream IrealmenI devices. • Air pollution control equipment is required • High treatment temperatures, as compared lo Ihemial desorption, can produce nitrogen oxides, sulfur dioxides, and PICs. • Solids wHh volatile metals may require additional treatment or more elaborate air pollution equipment. COSTS*'* $10-150rton $200-300Aon $200- 1700rton NOTES: (I) Actual performance and cost lor any remediation lechnolooy is highly sHe specific. Both depend inxin the original and target clean-up level concentrations ol contaminants, soil quantity to be treated, soU characteristics, and ttie d e s ^ andoperation of Ihe remediation lecnnology equipment used. o o H cn TABLE 4 Information Required for Characterization and TecfinoKogy Selection at VOC Sites INFORMATION RATIONALE FOR COLLECTING ^FORMATION REFERENCE All Technologies: Site Geology USQSScilClasslficalbn SoHMolslure Depth to Gioijnd W^ter Caitamhar< Msntity and Propeilles SVE Is irost effective In porous, permeable, homogeneous sol. Hl^ly heterogeneous soil Oe., fractured poibus lock or sands Interspersed with day tenses) may eDdilbit airRowchannelng hough NgHypeimeabfe soils. Abo, desorption Mnelios may be slow h some sluaticns (i.e., Nghorganic content a h i ^ clay content sol). In these cases, HBss transfer khelicsmay reduce Ihe raie of removal of SVE bebwthal whbhis expected by calctiallcns wlh a locd equlibritin model or pilot scab experhtents cairind od lor only a lew days. Often difuslon kinelbs Imitations can be substantiaiy icdUcedby proper des^n d ihe SVE facility. F a SVE to be effective, the sol must have siif icienl pneunalic permeabiity (>10'' cm^) to permi a^ lo move through Ihemedum. Sand/, gravely solb are tie nest oondjctlve to SVE, whib days and sifts are less ccnductive. However, remedaticns using SVE inchys and sifts have been successlul. Sdl permeablity may need to be measuredin tfie field. Hgh mdsture ccnieni h soil may dasticany decrease hs air permeaUlily and Vius, the effectiveness of SVE. The site must be sufficiently weft dahedtoprevent ihe severe leductlon inair penneabillty, which occifs when the peicent water ssturdbn d the sdl Is greater than 50%. Conveisdy, oiganics can be sliongly adsorbed onto exiiemely diy soib, which also inpedes SVE. The motsture content ol the sol will allect the amount d energy reqjired to heat Ihe sol, Ihe target teirperaluie and Ihe handling pioperlies d fine^grahedsdl. Theimal desoiplion requires that Ihe moisture center! ollhe sdl be less than 30%. SVE Is not effective In saturated sdl. However, the water table can be loweredby punplng. Theimal desoiplion and hclneratbn are more expensive lor Ngh moisture soil. Boling Pohl -Theimal desoiplion tarqet temperature is dependent on contamhan boiing poir<. \6pQr Pressuie • SVE is effective lor compounds iwilh a vapor pressure greater than 0.5 mm Hq at sol temperatures. Dhiensiorless Henry's Constant • SVE Is elteclive lor compounds wilh a dmenslonless Henry's conslant hlf^er than O.OI al soil tenpeiatures. Water Sdubility - SVE is more successlul lor compounds wilh lower solibilties. (Jquld and Vbpcr Oeteily • A conlaninant wilh a density areater tian water may form a DNAPL. A contamhant wlh a density less than water may torn an LNAPL. The nowcharacierlslicsof a compound:; vapor (or SVE Is a function d its vapor density. GuUance lor Conducting Remedial Investigations and FeeBlbilty audes under CERCLA ^p. 3-3 lo 3-20) EPA«40/G-89An4 ASTM D 2487 ASTM D 2488 ASTM D 2216 ASTMD30t7 GuUance lor Conducting Remedial kwestigations and Feaslbiity Sludes under CERCLA (pp. 3-3 to 3-20) EPA«40/Qfl9/D04 CFCChembalHandbod< o o l-» U l cn * » TABLE 4 Information Required for Characterization and Technology Selection at VOC Sites (Continued) INFORMATION- RATIONALE FOR COLLECTING INFORMATION REFERENCE Al Technologies: (continued) Contamlnarl Concentration, . Location, Vdume, and Depth Presence d Pipes a Sibsurfaca Material These data can be gathered via sdl mairix and'cr soil gas sampling. Soil gas sampling, both shallcw andat depths, may be mae aFpropilale, given depth to gound wder and sirallgaphy Thepresencaof water or electrical conddls. sol fractire Ibes. debris, or any other cbjocts thai are more permeable than the sunomdng sdl will be Ihe preferred pathway lor Ihe advecting gases. Gudance for Condiding Remedial trwesllgdbnsand Feaslbiity Studes Under CERCLA (pp. 3-3 to 3-201 EPA/54Q'G-89/004 Gedechdcal Techrtques SVE Only: Soll/AJr Filled Porosity Soll/Atr Permeability Soft Temperature Soil Humic Cod ent Contamlnari SollSoiplion Coofficled Kd (Since Kd Is less readlyavalable,Koc. the oqulibrium between cortaminanis soibed orto aganic carbon versus Ihe goundwaierisused.) Conlaminart Adsorption Characteristics on Aclivaled . Carbon Porosity shouldbe less than 40%lor SVE lobe effective. Soll/air permeablity shouU be geater than 10*^ cn^ lor air lo move Ihrou^ut the cortamlnated soft. SVE Is poledlally eRective In less peimeable soil (I e.. between 10 -6lo 10* 0 cn^), but further pibl-scale lest hg and^or mathematical modeing b recommendedlobelter predd Ihe ttne for deanup (vOiich Is llltely to be prolonged for lower permeability soil). Conlamharl vapor pressure, dknensloriess Henry's Law constart. water solibilly, and phase density are strong functions of temporal ire. Solvents adhere stron^y to sdl with high humb oortenl. which decreases Ihe eflediveness of SVE, Thb parameter describes the tendency of the sdvert to sorbodo sdl or organic matter In the sdl. Higher Koc's Indicate thai a subsurface Is more Ikely lobind to carbon rich meda (1 e. sol^ than lo remain In rater. Thb parameter Is related lo Ihe leaslbllty d remoUng contambarts from residuals by carbon adsoiptlon TNs parameter b Important since compounds such as MEK beoomeunstable as they areadsoibed onto caiboa Gubance for Conduding Remedial Ifwesligatbnsand Feaslbiity Studes Under CERCLA (pp 3^3 lo 3-20) EPA^54»G-89/004 Guidance for Conduding Remedial Imestigalbnsand Feasibilty Studes Under CERCLA (pp. 3-3 to 3-20) EPA/54»G-89/004 GuUance for Conduding Remedial Investlgalbnsand Feasiblity Sludes Under CERCLA (pp 3^3 to 3-20) EPA/54aG-89/D04 GuUance lor Conduding Remedial Irwestlgdbns and Feaslblily Studes Under CERCLA (pp. 3^310 3-20) EPA/540/G-8W004 RREL Treatability Database RREL Treatablllty Database o o CTl cr> M TABLE 4 information Required for Characterization and Technology Selection at VOC Sites (Continued) INFORMATION RATIONALE FOR COLLECTING INFORMATION REFERENCE Incineration and Thermal Desorption Only: Son PlaslicHy Soil BTU Content Contaminant Combustion Characteristics Son Particle Size Distribution Aficaline Metal Safts (e.g..NaS04,KS04) Volatile Metals Content (e.g..Hg,Pb,Cd,Zn,Sn) Plaslic soil, when subjected to compressive forces, can become molded Into large particles that are difficult to heat. The soil BTU content detemilnes Ihe luel requirements lor thermal desorption and indneration. Informalion on combuslion characleristics of a VOC Is required In order to determine the combuslbn characterlslics of the Incinerator. Thermal desorplion usually requires that soil be prelrealed to a maximum soil paiticte size ranging Irom 1 lo 2 Inches. Alkaline metal safts may cause relradory attack and slagging al high temperatures. High metal content may cause ash leaching and stack emissions problems. Guidance (or Conduding Remedial Investigations and Feasfeility Studies under CERCLA (pp. 3-3 to 3-20) EPA/540/G-89/004 ASTM D 3286 BencWPitot Testing ASTM D 422 Percentage of Na,K Heavy Metals Analysis 1 BTU s British Thermal Units LNAPL B Light Nonaqueous Phase Lk^uld DNAPL s Dense Nonaqueous Phase Lk]uid mm Hg « millimeters of mercury pressure NAPL e Nonaqueous Phase Llqiild PIC s Products of Inconqilete Combuslbn 3 APPENDIX A TECHNICAL BASIS FOR PRESUMPTIVE REMEDIES P W This Appendbc summarizes the analyses that EPA conducted of Record of Decision (ROD) and Feasibility Study (FS) data from VOC-contaminated sites which led to establishing soil vapor extraction (SVE), thenmal desorption, and incineration as the presumptive remedies for Superfund sites with VOC- contaminated soil. The analyses consisted of: • Identifying VOC-contaminated sites • Detenmining the frequency of technology selection for VOC sites • Identifying sites for ttie feasibility study (FS) analysis • Conducting the FS analysis. Results ofthese analyses, along with the scientific and engineering analysis of the performance data on technology application (Primary Reference document), provide a supportforthe decision to eliminate the initial altematives identification and screening step for this site type. These technical reviews found that certain technologies are appropriately screened out based on effectiveness, implementability, or excessive costs. Review of technologies against the nine criteria led to elimination of additional altematives. Provided below is a discussion of each analysis. Identification of VOC-Contamtnated Sites The first analysis involved generating a list of signed Records of Decision (RODs) (post-SARA), documenting VOC contamination, from which data could be used for subsequent analyses. The ROD Information Directory database was used for this purpose. Of the 821 signed FY86-FY91 RODs, 418 are identified in the database as containing VOC contamination in source material. This list of RODs was subsequently divided into two lists: RODs wttere VOCs were the only contaminants of concem identified in the source material and RODs containing VOCs, as well as other contamination, in source material. For those RODs involving VOC plus other contaminants, a review of the ROD document was conducted to identify cases where only VOCs were driving tJie selection of remedy. To make this determination, the Remedial Response Objectives and Selected Remedy sections of the ROD were reviewed to identify specific language indicating that the remedial action was designed to address only the VOCs at the site. In addition, if cleanup goals were specified only for VOCs, the assumption was made that VOCs were driving the remedy. As a result of this analysis, 88 RODs were identified as VOC-onty RODs or VOCs plus other contaminants RODs where a clear detenmination could be made that VOCs were driving the selection of remedy. Frequency of Technology Selection for VOC-Contaminated Sttes Table 1 presents the distiibution of the 88 FY86-FY91 RODs among the treatment technologies used to address VOCs in soil. This table demonstrates that the three presumptive remedies (SVE, themnal desorption, and incineration) together were selected more often (over 90% of the RODs analyzed) than the otiier applicable technologies. Presumptive Remedies were also those remedies where a fair amount of performance data on technology implementation was available. Furthermore, SVE, chosen in over two-thiras of tiie RODs analyzed, was the primary presumptive remedy selected. Identification of Sites for Feasibilftv Studv_Analvsis The purpose of the FS analysis was to document the technology screening step in FSs of VOC- contaminated soil/sludge sites and identify the principal reasons given for eliminating technologies from further consideration. To achieve a representative sample of FSs for the analysis, sites were selected using ROD data according to the following criteria: 13 400157 APPENDIX A TECHNICAL BASIS FOR PRESUMPTIVE REMEDIES (Continued) Table 1 Presumptive Remedy VOC Site Treatment Summary Table, FY86-FY91* TECHNOLOGIES USED TO ADDRESS VOCs IN SOIL Bioremediation <' Incineration Soil FlushingA/Vashing <" 1 Soil Vapor Extraction Thermal Treatinent •'' Total TOTAL 3 11 3 62 9 88 Source: Notes: ROD Information Directory (RID), FY86 - FY91 (1) Relatively limited amount of periormance data available for these technologies versus the presumptive remedies. (2) Thermal ti-eatment includes RODs employing thermal desorption, thermal aeration, low-temperatijre themial desorption, and the generic remedy thermal ti'eatmenf. A population of 418 RODs was identified for this study based on the parameters: FY 1986-1991, and VOC contamination of source media. Sites were chosen, based on the selected remedy, to ensure an even distribution among the five treatment technologies for VOCs in soil (i.e., bioremediation, incineration, SVE, soil flushing, and thermal tiBatment). Whenever possible, both VOC-oniy sites and VOC and otiier contamination sites were represented under each technology. Sites were selected to ensure an even distribution in geographic location, ROD signature date, and site size. Feasibility Study Analysis The FS analysis involves a review of the technology screening phase, including any pre-screening steps, followed by a review of the detailed analysis and comparative analysis phases in each FS and ROO. Information derived from each review was dcxnjmented on site-specific data collection forms, which are available for evaluation as part of the Administrative Record for this directive. (See 'Feasibility Study Analysis for CERCLA Sites with Volatile Organic Compounds in Soils', September 1993, available at EPA Headquarters and Regional Offices.) I 400158 14 I APPENDIX A TECHNICAL BASIS FOR PRESUMPTIVE REMEDIES (Continued) P For the screening phase, tiie full range of technologies considered was listed on the data collection forms, along with the key reasons given for eliminating technologies from further consideration. These reasons were categorized according to the screening criteria: cost effectiveness, or implementability. The frequency with which specific reasons were given for eliminating a technology from further consideration was ttien tallied and compiled into a screening phase summary table (Table 2). For the detailed analysis and comparative analysis, information on the relative performance of each technology/alternative with respect to the nine NCP criteria was documented on the site-specific data collection forms. The advantages and disadvantages associated with each dean-up option were highlighted. In some cases, a VOC technology was combined with one or more technologies that address minor site contaminants into one or more altematives. Only the component of the altemative which addressed the VOC contamination was evaluated in this analysis. The disadvantages of a technology/ altemative were then compiled into a detailed analysis/comparative analysis summary table, under the assumption that these disadvantages contributed to non-selection. All summary tables are available for review as part of the Administrative Record. The FS analysis has been completed for 21 sites (representing approximately 25% of universe studied). The information from these FSs has been compiled and summarized in Table 2. Additional FS analysis is planned and will be added to the Administi-ative Record, when available. Table 2 demonsti^ates tiiat technologies, other than the presumptive remedies, are consistently eliminated from further consideration in the screening phase due to effectiveness, implementability, or excessive costs. In addition, the analysis indicates that, although certain technologies routinely passed the screening phase, tiiese technologies were selected infrequentiy because ttiey did not provide the best overall performance with respect to the nine criteria. Together these analyses (Appendbc A to tills directive and "Feasibility Study Analysis for CERCLA Sites with Volatile Organic Compounds in Soils'), along with the scientific analysis of performance data (USEPA (In Progress) Contaminants and Remedial Options at Solvent Sites) will supporf the decision of using presumptive remedies and bypassing the technology identification and screening step for a particular site. As previously indicated, this factsheet and accompanying analysis should be part of tiie Administrative Record for the site. Further supporting materials, not found in the Regional files, can be provided by Headquarters, as needed. W 15 400159 TABLE 2 • SUMMARY OF SCREENING AND DETAILED ANALYSIS FOR VOC SITES' _ y ^ y^^\/^^ y ^ y ^ iFs«wh«r» y ' y " REMEDIAL A ^ J ^ y ^ S ^ y ^ ^ y crii.rioncontribui.d y y . TECHNOLOGY X ^ r f . * ! ^ . J ^ X . # \ > l ^ K-^^V^ TO Scr»«ning OUI •^^«'^ y S Z ^ y 1 ^^''XM^^^^^^^y'f'^ Capping Ollsite Nonharardous 1 nnrilill aisile RCRA Disposal Onsite Encapsulation Onslle Nonhazardous Landfill Onslle RCRA Landfill Activated Sludge Composting Land Farming Bioremediation (unspecilled) Ex-situ Bioremediation In-sllu Bioremediation Dechlorination/ APEQ 2t 4 16 3 2 14 1 4 3 6 7 tt 3 e 0 12 1 0 1 0 1 0 0 t 1 0 7 2 4 2 1 It 1 3 3 6 6 to 3 6 2 2 0 1 2 0 0 0 . 0 0 0 0 1 0 1 t 0 0 0 0 0 0 2 2 0 6 2 3 1 1 B t a t 5 5 9 3 2 1 3 0 1 7 0 0 0 0 2 0 0 0 0 0 0 0 1 0 0 e 0 to 1 0 1 0 1 0 0 0 0 0 5 0 3 0 0 0 0 0 0 0 0 0 0 y ^ » RODS Wliere Criterion Contributed lo Non-Selecilon / * 3 0 6 0 0 0 0 0 0 0 0 0 0 ' ^ ' 7 0 7 1 0 1 0 0 0 0 0 0 0 ^ 6 0 3 0 0 0 0 0 0 0 0 0 0 ^ ^ 6 0 9 0 0 1 0 1 0 0 0 0 0 3 0 5 0 0 1 0 [ 0 0 0 0 0 0 1 0 7 0. 0 0 0 1 0 0 0 0 0 [ ^ " " " " - • • " • • " - • • • • • • '^ " " " " " " " " " " " " " 3 % o o TABLE 2 • SUMMARY OF SCREENING AND DETAILED ANALYSIS FOR VOC SITES (Continued)' REMEDIAL TECHNOLOGY OR TREATMENT' Other Chemical Destruction Reduction NeulraNzalion Oxidation Ollsile Inclnerallon (unspecilled) Onsite 1 Inclnerallon 1 (unspecified) Ruidlied Bed 1 Inlrared 1 Pyrolysis Multiple Hearth Rolary Kiln other Incineration other Thermal Treatment 3 7 6 6 16 7 5 5 3 ] 5 It 13 6 y y^^y^K y y iFsswi)«» y y y ^ J ^ y ^ y ^ J ^ y ^ ^ y Crll.rtonConti1bul.<J y y C 0 0 0 1 7 1 0 t 0 0 6 1 0 3 6 6 5 B 1 ^ 4 4 3 4 3 12 6 0 1 0 0 1 0 1 0 0 1 2 0 0 0 0 0 -0 5 2 3 2 2 2 3 5 2 3 5 S 4 5 3 1 2 1 4 2 6 4 0 t 0 0 2 5 2 1 1 1 3 5 3 0 0 0 0 0 0 0 1 0 0 2 1 0 0 0 0 1 7 1 0 0 0 0 4 0 0 0 0 0 0 2 0 0 0 0 0 t 0 0 y V 0 0 0 0 0 0 0 0 0 0 0 0 0 1 RODS Where CrHerlon Contributed to Non-Selectlon w ^ 0 0 0 0 1 0 0 0 0 0 0 1 0 0 v*-"^ k^-^- 0 0 0 0 0 0 0 0 0 0 0 j 0 0 k^ 0 0 0 t 7 , 1 0 0 0 0 5 0 0 CP* 0 0 0 1 6 1 0 0 0 0 3 0 0 \y 0 0 0 t 2 0 0 0 0 0 4 0 0 VS^ " " " " " • • - " • • " " ^ " • •• " •• I TABLE 2 • SUMMARY OF SCREENING AND DETAILED ANALYSIS FOR VOC SITES (Continued)' RFUFmti / Jv y r ^ y s ^ y ^ i ^ y Cflt»rton ContitbutMl / / 0" y ^ i ^ y ^ y ^ ^ y . ^ X » V / ^ ^ ^ ^ ^ ^ ^ < A 1 ThEAT«ENT»/^,^gii^^?'''^>^C^,,^ Viliification Wet Air Oxidation Low Temperature Thermal Desoip/ Stripping In situ Steam Stripping Sofl Flushing Sol Washing InsRu Vacuum Extraction B.E.S.T. Process LIquilied Gas other Physical Extraction Fixation StabBlzation/ Solldincallon Aeration 12 6 t3 3 15 14 17 1 1 4 7 13 12 1 0 1 10 2 3 2 11 0 0 0 1 2 2 11 5 3 1 12 12 6 1 1 4 6 7 10 1 0 0 0 0 0 0 0 0 0 0 4 0 2 1 1 0 0 1 0 0 1 0 0 0 1 8 4 1 1 9 10 6 1 1 3 6 6 9 5 3 2 0 5 9 2 0 1 0 0 2 2 0 0 3 2 0 0 10 0 0 0 0 0 1 0 1 7 0 3 2 2 0 0 0 1 2 1 0 0 2 0 1 0 0 0 0 0 0 0 0 y ^ 1 n0D$ Where CrHerlon Contributed lo Non-Selection , s > ^ 0 0 1 0 1 0 0 0 0 0 0 0 0 ^ \'-* 0 0 t 0 t t 0 0 0 0 1 2 0 ^»!^ v ^ " ' - 0 1 2 0 2 0 1 0 0 0 1 2 • , ^ ^ 0 1 7 0 2 2 0 0 0 0 0 2 1 d ^ 0 1 3 0 1 2 0 0 0 0 1 0 1 • 0 0 4 0 3 1 2 0 0 0 1 2 0 ^ •• •• -- •• -• -- • • •• •• -- -- •• •• ^ • • • • • • • • • • • • • • • • • • -- -- •• •• 3 1 vo TABLE 2 • SUMMARY OF SCREENING AND DETAILED ANALYSIS FOR VOC SITES (Continued)' 1 y yy^y*. y y iFSiWh«ri / y REMEDIAL y J» ><^*/l'3v^ .s'V^ crti«rionContrib^^ / y T R E A T M E N T ' / ^ , ^ ^ ^ ^ : ^ ^ ^ ^ ; ^ In-silu 1 Hydrolysis Soil Slurries 4 1 0 0 4 1 0 0 0 0 3 t 2 0 0 0 0 0 0 0 ^ y f RODt Whsr* Criterion Contributed to Non-Selection 0 0 0 0 ^ 0 0 , ^ ^ 0 0 ^ 0 0 ^ 0 0 ^ " " ^ ' " " o o H C\ Ui ^ This study was conducted on 21 RODs and their corresponding FSs. 2 This does no! the Include the noacliofl or institutional control only alletnatives. No RODs selected either ol these as remedies. 3 FSs and RODs may contain mora than one criterion lor screening or non-selection ol tachnotogy. Also, some FSs did not luily explain Ihe criteria lor screening out a technology. Thus, the totals lor screening and non-selection criteria are not equal to Ihe nunter of FSs end RODs considered. * tntonrallon on Stale and community concerns wes not Included in this enalysls because FSs do not contain this inloimallon and RODs generally only relerence supporting documentation (i.a.. State concurrence letter and responsiveness summary). o o M s;5> APPENDIX B Criteria Evaluation for Technologies Used to Treat VOC-Contaminated Soil g y o < H UJ CC 2 ^ Ll o (/) CRITERIA Overali Protection of Human Health and the Environment • Provides boti short- andlong-lemn . protection by redudng concentration and exposure lo VOCs in soil. • Depending on site- specHic oindRlons, prevenlsfuifier gotnd water oontamhalion. Compliance With Federal ARARs • Does not trigger LORS because 1 does not involve ptacemeilol waste. • Because wasle is removed h place tiiDiighl'imiled construction and no excavation, lewlmpads lo welands.lboc^lalns.or water quality are Ihely. • DependngonsHe-spedlic condlions. treatswaslesto levels IhalwnpiBvem 1 exceedance o( goundwater clean-up levels • Emission coniroisiffe needed b ensure ccmpTiance wHh air qieity standards. Long-Term Effectiveness and Permanence • Elecliveiy removes contamination souice. • Isawell-demonslraled lectniquelorremovng VOCsliomsoil'sludge. • Requires some treatnenl d residuals (spent carbon or concentialed VOC wasle stream) generany t i r o j ^ regeneralnnordisposal. * Hazardous wastes leil h placewin require 5-year review. Reduction of Toxicity, Mobility, or Volume Through Treatment • SigiHicanJy reduces toxicity, mobility, or volume through IreatmenI • Produces lew waste streams. Short-Term Effectiveness • Does not present substantive li^stoonsltewoiltersa community; potential (or some dust generation during wellinstallc(tan. • Potential air emissions are easily controlled throu^ activated carbon adsorption or other technologies. • Generally irwolvesrelallvely shot lime liame to achieve clean-up levels: however. difficulty in estimating timeframe ma/ exist due to site uncertainties (e.g. irregular soil permeabBif es). • Ellective lor treating waste under buildings. Can be perfoimed on ea\jB lacilities. • Hardware, such as vacuum blower, is readily available from many sources, but SVG system perfwmance Is highly dependent upon Vie lithology ollhe site arid system design. Implementabiilly • Few admlnlstraliva dUffcuftles. Technology b readily availsbleliDmmary sources. • lised suocessfrilty 8t numerous Superiund sHes lo address VOC contamination. • Instanhg and operating exTactlonweffs requires (ewer engifieering controls than other technoioaies (i.e., excavation andf Incheralion). • Requires series d sol gas sampling b deleimiie when dean-if) levels are achieved. 1 Co.l<" $10-15(Vton $5tyion avg 1. Note: Aclial cosi of a lemedalicn technology Is highly ste-speclic. II Is dependent upon Ihe orlgbal and target clean-up level conoedratlons ol cortamlnanls. sol characteristics, and Ihe deslgi and opetalbn d fie remedialbn technology used. 3 '#• • % APPENDIX B Crileiia Evaluation for Technologies Used to Treat VOC-Contaminated Soil (continued) K i o o cn g o U) UJ o i z iC lU z H CRITERIA Overall Protection of Human Health and ihe Environment • Provides both shoit- and tong-term prdectionby elhiindingexpostrelo VOCshsoiVsludgB. * Prevents lurther gcundwaler contaminalion and dlsHemigialion. * Requires measures lo prdecl workers and commiriy during excavation, handing, and IreatmenI. Compliance Wilh Federal ARARs 1 4*WV I B I ^ ^ l l r ^ l l l V • Reqiires compliance with RCRA removal, IrealmenI, l'ansportalion(il ollsite teabierl), and land dsposal regulations (il a ha zaidous waste). • Excavation, consliuclbn, and operation oi onsite t^eabtenl unit may reqiira compfiance with wetlands anddherbcation-speciic ARARs. • Treats hazardous waste lo BDATtovels;lhu$,lhereis no LOR problem wJh residuals. • Generally, tresis wastes lo levels ttalwil prevent exceecbnce oi groutd- wdercleanup levels. • EmissnnconliDlsare needed to ensure compliance with air quality standanJs. Long-Term Effectiveness and Permanence • Elleclively removes contamnalion source. • Is a weR-demonstrated technique lor removing VOCs Irom soil/studge. • bvdves some IreatmenI or disposal ol residuals generally Ihrou^ used caibon acfcoiption' regeneration or dsposal. Reduction of Toxicity, Mobility, or Volume 111 rough Treatment * Signilicantly reduces toxicity, mobility, or w l i m e d contaminants tirough freabied. ' Generally requires test rms to ensure ellective treatment. Short-Term Effectiveness b l l v V ( l W l l V W ^ • Presents potential short- term risks b workers and community Irom air release during excavation and IredmenI (H onsile IreatmenI). ' Involves pdediai short-term riskslrom handling and transporting waste (tf ollsile treatment). • Relatively short limdrame lo achieve clean-up levels. Implementability * Constmction and substantia permit requirements ol an onsite liealmer< unit may presert somedllicullies. Mobile bcineralion units b r onsile treatment are available. • LimHed ollsile IredmenI capacity exists. * Usedsuccesslullyddher • Superiund steslo address solvent contambdbn. * Requires engineering measures looodrol air emissbns.lugitivedust, run-di.erosbnand sedmentaf on, site access; andtransportatioa C o , . " ' $200-300/ ton $2504on avg. t. Note: Actual cost of a remeddion lechndogy is highly sHe-spedf c I is depended if)on Ihe orignaland target clean-up level concenlratkns d oortaminads, soil charaderislks, and Ihe desi^i and opeiaf on ol Ihe remedaticn technobgy used. o o M a\ ^ APPENDIX B Criteria Evaluation for Technologies Used to Treat VOC-Contaminaled Soil (continued) ai Q 5 oc IU z o 2 CRITERIA Overall Protection of Human Health and Ihe Environment • Provides bdh short-and bng-term proleciion by efiminallng exposure lo sdvent contaminants In sdl. • Prevents luilher ground- water conlamlnatbn and ofslemtgafon. • Requires measures to piotedwortrersand community durbg ecavalbn, handng, and treatment. Compliance Wilh Federal ARARs f « w w i ( i i ' ^ i > n i 10 • Reqdres compliance wifi RCRA removal, treatment, IransportatbnCilollate IrealmenI), and land disposal regddbns (da hazardous waste). * Excavatkn, construdbn, and operalbn d onsite bclnerdors may require complance wVi wetlands and otier bcdnn-specilb ARARs. • Treats hazardous waste lo BOATtovels;t)us.^ereis no IDR problem wlb residuals. * Treats wastes b tovels Ihal wipievenl exceedance d ground-walerdeanHip tevels. • Emissioncodrobmaybe needed b ensure compliance wib air quality standards durbg excavalbn andconskuctbn. Long-Tenn Effectiveness and Pennanence • Elleclively destroys source oloontaminadon. • Is a well-demonstrated ledidque br Ireaing VOCs h soiVsludge. • No organic residuals codamlnatbnwIBexblil tredbgsoA/sludge cortaminatedortywith VOCs. Reduction of Toxicity, Mobility, or Volume Through TVeatmenI • Signilicanlly reduces loxfcily.mobilily.or vdume dcontambants throu^ treatment. Short-Term Effectiveness . Presenbpdental short- leim risks b wortcers and community from air release during excavaScn and treatment (il onsite treatment). • Involves pdentld short- term risks Irom handng and transporting waste (H ollsile tredmeni). . Relatively short timelrame to achieve clean-up toveb. Impiementabliily * Construdbn and subsiantve permit raquiremenbolan onslle incberalor may besonoewhatdiicul. Mobile bclnerdors are raadily avaUdble. . LbiHed dlsHe hcineiatbn capacAy exists. • Used successlully at ober Sif>eriund sites toadiessVOC coniamlnatbn. t C O . . ' " $200-1700/ ton $40(ytonavg 1. Note: Actual cod ol a nemedlalbn technobgw is hi^ly sle-specilb and depended upon the o r l ^ d and target dean-up level conoenlrdkns ol codambants. so8 characteristics, and Ihe design and operaton ot the remedallon technobgy used. 4. 3 % . ^ I w p w APPENDIX C II U.S. Waste CALIFORNIA WASTE EXCHANGE Rotjert McCormick Department of Health Services Toxic Substances Control Division 400 P Street Sacramento, CA 95812 (916)324-1807 INDIANA WASTE EXCHANGE Environmental Quality Control 1220 Waterway Boulevard P.O. Box 1220 Indianapolis, IN 46206 (317)232-8188 INDUSTRIAL MATERIAL EXCHANGE SERVICE Diane Shocicey 2200 Churchill Road, #31 Springfield, IL 62794-9276 (217) 782-0450 FAX: (217)782-9142 INDUSTRIAL MATERIALS EXCHANGE Bill Lawrence 172 20th Avenue Seattle, WA 98122 (206) 296-4899 FAX: (206)296-0188 PACIFIC MATERIALS EXCHANGE Bob Smee 1522 North Washington Street, Suite 202 Spoicane, WA 99205 (905) 325-0551 I FAX: (509) 325-2086 NATIONAL WASTE EXCHANGE NETWORK 1-800-858-6625 RENEW Hope Castillo Texas Water Commission P.O. Box 13087 Austin, TX 78711 (512) 463-7773 FAX: (512)463-8317 Exctianges INDUSTRIAL WASTE INFORMATION EXCHANGE William E. Payne New Jersey Chamtser of Commerce 5 Commerce Street Newark, NJ 07102 (201)623-7070 MONTANA INDUSTRIAL WASTE EXCHANGE Don Ingles Montana Ctiamber of Commerce P.O. Box 1730 Helena, MT 59624 (406) 442-2405 NORTHEAST INDUSTRIAL WASTE EXCHANGE Lewis M. Culter 90 Presidential Plaza, Suite 122 Syracuse, NY 13202 (315) 422-6572 FAX: (315)422-9051 SOUTHEAST WASTE EXCHANGE Maxi May Urban Institute Department of Civil Engineering University of North Carolina Charlotte, NC ?n??.3 (704) 547-2307 SOUTHERN WASTE INFORMATION EXCHANGE Gene Jones P.O. Box 960 Tallahassee. FL .??313 (904)644-5516 FAX: (904)574-6704 • 23 400167 APPENDIX D GLOSSARY ^pplJcableorRelevantandApptT)priate Requirements £AEA^-CERCLA Section 121(d) aad the NCPrequiie liiat onsite remedial actions must attain (or justify a waiver of)requirements of enviroiimeDtallaws ttiaiaie deiermii^ to t>e Federal or more stringent State applicable or relevant and appropriate requirements. Dense Non.Aqt»eoiisPha5;efjQuidfDNAPT.UDNAPI.< are iaimiscible bydrocari>OD liquids ttm are denser tiiaa water, such as chlorinated solvents (either as a single component or as mixtures of solvents), wood preservative wastes, coal tar wastes, PCBs and some pesticides. DNAPLs can sink to great depths, can penetrate into bedrock fracmres, can move as a liquid in a direcdon different from the flow of groundwater and can act as a continual source of groundwater contaminadon over dme. Engineering Evaluation/Cost Assessment CEE/CA) - An analysis of removal alternatives for non-time chdcal removal acdons. Ex-Situ Treatment- Removal of material from the ground for treatment Feasibility Study (TS") - A description and analysis of the potential clean-up altemauves for a site. It is generally conducted concurrently with the remedial invesdgation (RI); together the smdies are referred to as an RI/FS. (See remedial invesngadon.) In-Situ Treatment - The treatinent or remediation of media occurring in-place. Innovative TreatmentTechnologies - Technologies that have been tested, selected, or used for treatment of hazardous substances or contaminated materials but lack well-documented cost aod performance data underavariety of operating condidons. Land Disposal Pf^rtricrinn^ fr.DRO - Tbe Hazardous and Solid Waste AmeoduKots (HSWA) to tbe Resource Conservation and Recovery Aa (RCRA) include specific restrictions on die land disposal of RCRA hazardous wastes. These restrictions, known as LDRs, prohibit tbe land disposal of restricted RCRA hazardous wastes unless these wastes meet treatment standards specified io 40 CFR 268 of other compliance options. Light Non-Aqueous Phase Liquids (LNAPL) • Like DNAPLs, LNAPLs are immiscible liquids, butare lighter than water and therefore float on water. As they are lighter than water, they are most frequendy found at the ground- water table/vadoze zone inter&ce. Record of Decision (ROD) - A public document that explains tbe basis for selecting the clean-up altemaDve(s) that will be taken or served under CERCLA. Remedial Design (RD^-The remedial action that involves designing and testing to determine whether the remedy wUl be effective at a site. Remedial Investigation fRT - An in-dgprh sniriy >W4gn>H to gather the data necessary to determine the nature and extent of the threat posed by contamination at a Superfund site. It also helps to establish the preliminary criteria for cleaning up die site in the FS aod supports the technical and cost analyses of the altematives. It is generally completed and combined with the FS and rcfisrred to as tlw RI/FS. Risk Assessment - The qualitative and/or quantitative evaluation performed in an effon to define the risk posed to human health and/or the enviroimient by actual and potential exposures to specific pollutants in air, water, soil or other media. Superfund Accelerated Cleanup Model rSAOVi^. An inicaiive designed to accelerate all aspects of the S uperfund clean-up process. Vadose Zone - The zone in soil that lies above the pennanent water table. Volatile Organic Compounds (VOCs) - Any organic compound which readily dissipates into the air. 400168 24 I p V REFERENCES Primary Reference: U.S. EPA Gn-Progress). Contaminants and Remedial Options at Solvent Sites. Compound Properties: RREL Treatability Data Base • Available dirough AXnC (Contact Glenn Shaiil (513) 569-7408) General Site Investigations: U.S. EPA. 1986. A Compendium of Superfund Field Operation Mediods. EPA/540/87/001. U.S. EPA. 1988. Guidance for Conducting Remedial Investigations and Feasibility Studies Under (TRCLA. EPA/540/G-89/004. October. U.S. EPA. 1989. Guide for Conducting Treatability Studies Under UbRG-A, Interim Final. EPA/540-2-89/. 058. U.S. EPA, 1991. Soil Sampling and Analysis for Volatile Organic Compounds. EPA/540/4-91/001. Incineration: Dempsey, CJt and Oppett. E.T., "Incineration of Ha7ardous Waste: A Critical Review Update". Intemanonal Journal of Air Pollution Control and Ha7;)rdous Waste Management. Volume 43, January 1993, pp. 25-73. U.S. EPA, 1990. MobUe/Transportable Incineration Treatment Engineering Bulletin. EPA/540/2-90/014, February. Presinnptive Remedies: U.S. EPA (In-Progress). Presumptive Remedies: Policy and Procedures. U.S. EPA (In-Progrcss). Presumptive Remedies: Remedial Strategy and Treatment Technologies for CERCLA Sites witii Contaminated Groundwater. Soli Vapor Extraction: U.S. EPA, 1991. Soil Vapor Extraction Technology Reference Handbook. EPA/540/2-91/003, February. U.S. EPA, 1991. In-Sinj Soil Vapor Extraction Treatment Engineering Bulletin. EPA/540/2-91/006, May. U.S. EPA, 1991. Guide for Conducting Treatability Studies Under CtKCLA: Soil Vapor Extraction. EPA/540/2-91/091 A, September. U.S. EPA, 1992. A Technology Assessment of Soil Vapor Extraction and Air Sparging. EPA/600/R- 92/173. September Thermal Desorption: U.S. EPA. 1991. Thermal Desorption Treatment Engineering Bulletin. EPA/540/2-91/008, February. U.S. EPA, 1991. Guide for Conducting Treatability Studies Under LtRCLA: Thermal Desorption Remedy Selection - Interim Guidance. EPA/540/R- 92/074A, September. Additional References: U.S. EPA. 1991. A Guide to Principal Threat and Low Level Threat Wastes. Superfund Publication 9380.3-O6FS. U.S. EPA. 1991. Risk Assessment Guidance for Superfund, Volume I: Human Health Evaluation Manual, Part A. EPA/540/1-89/002. December. U.S. EPA, 1989. Risk Assessment Guidance for Superfund, Volume II: Environmental Evaluation Manual. EPA/540/1-89/001, March. U.S. EPA. 1991. Compendium of CLRCLA ARARs Factsheets and Directives. EPA Publication 9347.3-15, October. 25 400169 I 4 «l ?,BA United States Environmental Protection Agency Washington. D.C. 20460 Official Business Penalty for Private Use S300 d 400170 ^^