USVI Public Records

Document text

UNITED STATES ENVIRONMENTAL PROTECTION AQENCY NOV231994 DATE: Biological Technical Assistance Group Meeting 3JECT: Pnase u Remedial Investigation for Tutu Wells FROM: Shari Stevens, Coordinator Biological Technical Assistance Group (ESD-SMB) TO: Caroline Kwan, Remedial Project Manager New York/Caribbean Super fund Branch 2 (NYCSB2-E) The following comments represent the consensus of the Region II Biological Technical Assistance Group (BTAG) review as discussed during the BTAG meeting of November 17, 1994. The document reviewed by the group was the "Phase II Remedial Investigation," dated August 1994 and prepared by Geraghty and Miller, Incorporated, for the Tutu Wells site in St. Thomas, U.S. Virgin Islands. The BTAG has previously raised a concern regarding the possible presence of a wetland system downgradient of the groundwater plumes and Turpentine Run. Since you have confirmed that a forested wetland does exist south of the site, it will be necessary to include documentation of groundwater discharge points in the vicinity of this wetland, along with a description of the wetland itself. If groundwater is not discharging into the wetland, this should be documented in the RI. However, if groundwater is entering the wetland, contamination may be transported from the site to this valuable habitat. This is especially a concern since the groundwater plume is travelling south toward the wetland, with a probable DNAPL present. In order to comply with federal wetland ARARs, the three parameter method should be used if delineation of the wetlands becomes necessary. Also note that a wetlands assessment and restoration plan will be needed for any wetlands impacted or disturbed by contamination or remedial activities. Should you require additional information regarding wetland issues, the BTAG and/or John Cantilli (212-264-6081) of the Marine and Wetlands Protection Branch are available for assistance. "The Upper Turpentine Run, which drains the Tutu Wells site from north to south, has been channelized in a storm sewer as part of the development of the valley" (page 3-2) . The installation date of this enclosed storm sewer is not provided in this report. It is not clear whether the Run had previously been an open system, allowing site contamination to be transported downstream through the surface water. Turpentine Run is another possible route of contaminant transport into the downstream wetland area that may need to be considered. The Phase I RI previously included the collection of surface soil samples from three locations on this site (SS-3 through SS-6) . Although these surface soil sampling locations are depicted in Figure 1-3, it ,is still unclear where the high surface VOC and , , /.«• I I'- F' ' •' s ,' ' : V^:'- \ \ • • " REGION II FORM 132O-1 (9/86) '' TUT 006 0562 *64621* 64621 SVOC concentrations exist. Tetrachloroethylene was detected at a maximum concentration of 440 ppm in the surface soil (Table 2-2 of the Endangerment Assessment EA). However, it is not stated at what sample location this was detected. A table of the individual contaminant concentrations detected in the four surface soil samples should be included in this RI. This will enable an accurate assessment to be made of the extent of surface soil contamination and any possible ecological exposure risks. It will also help us determine whether the extent of surface soil contamination has been adequately defined and whether any further sampling may be necessary. It should be noted that Figures 5-2, 5-6, and 5-11 in this RI, which depict the surface soil sampling results, do not contain any of the high hits of surface soil VOCs or SVOCs that were reported in the Endangerment Assessment for these four surface soil sampling locations. This discrepancy should be clarified. It is stated on page 5-5 that "for metals and other inorganic compounds, impact to soil for a particular constituent was considered if the analytical result exceeded the background value by at least one order of magnitude...11 This use of a multiplier is inappropriate when screening for ecological contaminants of concern. Site contaminant levels should instead be compared to the average detected background concentrations. This is a more conservative approach for the initial screening of site contamination. The criteria for determining whether a property had soil impacted by VOCs or petroleum products, and thus whether soil remediation is warranted, are listed on pages 5-3 through 5- 5. There is no consideration of ecological toxicity values for terrestrial receptors reflected in these criteria. This needs to be addressed when considering surface soil remediation. The STAG is interested in reviewing any future documents pertaining to this site. We are also interested in obtaining feedback regarding the usefulness of our comments. If you have any questions, comments, or require further information, please contact me at (908) 906-6994. cc: Carole Petersen, ERRD-NYCSB2 Mel Hauptman, ERRD-NYCSB2-E Mark Sprenger, HQ-ERT Gina Ferreira, ERRD-PSB John Cantilli, WMD-MWPB Diane Wehner, NOAA Felix Lopez, USFWS Bob Witte, OPM-EIB Karen Kraco, TAT Jane McGuire, ESAT TUT 006 O563