ARCHIVED REPORTS XR0000283 - Laserfiche WebLink

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Maximum methyl tert-butyl ether (MTBE) concentrations of 277 and 99 µg/l have been detected in groundwater samples analyzed by EPA Test Methods 8020 and 8260, respectively Historical groundwater flow beneath the Site is directed to the east and southeast A summary of historical analytical groundwater data is tabulated in Appendix A ' In February 2000, the mass of petroleum hydrocarbons in soil was estimated at approximately 485 Pounds for TPHg and 8 pounds for benzene The mass of petroleum hydrocarbons in groundwater ' beneath the Site was estimated to be approximately 2 grams of TPHg and 0 7 grams of benzene The groundwater plume beneath the Site may extend beneath B Street Review of the historical soil analytical data indicates petroleum hydrocarbon impacts at intervals between 35 and 66 feet below the ground surface (bgs) with the exception of the tank removal soil samples collected between 12 and 14 feet bgs Approximate locations of the groundwater monitoring wells are depicted on Figure 2 ' FIELD ACTIVI'T'IES Death to Groundwater Measurements, On March 18, 2003, representatives of Geocon measured the depth to groundwater in monitoring wells MW-1 through MW-12, VW-1 and VW-2 using a battery operated water level meter The measurements were obtained from a surveyed reference point at the top of the well casing (TOC) The approximate well locations and site features are depicted on Figure 2, Groundwater Elevation Map -March 2003 1 During the First Quarter - 2003, the depth to groundwater in wells MW-1 through MW-12, VW-1 and VW-2 was recorded between 50 36 and 52 02 feet below TOC Based on the March 2003 groundwater elevation data, the groundwater beneath the Site appears to be directed toward the southeast at an approximate gradient of 0 003, which is consistent with historical groundwater flow A review of the last reported groundwater level measurements for the Site indicates that from ' December 2002 to March 2003 the groundwater levels in each of the wells increased an average of 1 I feet A summary of the TOC elevations, depth to groundwater measurements and Mean Sea Level groundwater elevations is presented on Table 1 ' Well Pureing and Samphn>� ' On March 18, 2003, approximately three well volumes of water (30 to 61 gallons) were extracted from each well utilizing a 2-inch diameter submersible pump During the well purging activities, the groundwater was monitored for pH, electrical conductivity, temperature and turbidity This information is included on the Monitoring Well Sampling Data Sheets presented in Appendix B Following the purging activities, groundwater samples were collected from the wells and decanted into four 40-milliliter volatile organic analysis vials and one one-liter amber glass bottle The samples were sealed, labeled, placed in an ice chest containing ice, and subsequently transported to the laboratory using standard chain-of-custody protocol The extracted groundwater was placed into 14 Department of Transportation-approved, 17-H, 55- gallon drums and temporarily stored onsite pending receipt of laboratory analysis The drums were transported by ABCO Environmental Services to an appropriate disposal facility in April 2003 Project No S8475-06-24D -2- April 28,2003