ARCHIVED REPORTS_XR0011298 - Laserfiche WebLink

Home Browse Search

Geological Technia lnc. Page 7 ' Additional Site Characterization and 31 Quarter Groundwater Monitoring • Project No.989.2 October 31,2002 ' 3.1 Analytical Results SOIL In summary: • Minor concentrations of BTEX constituents and TPH-G were found near the capillary fringe in the 10,5 to 11 foot sample from MW-101. ' • The 30.5 to 31 foot sample from MW-101 was non-detect for all analyzed constituents. • MTBE was non-detect in all samples collected from MW-101. 1 • MW-7 and MW-9 were non-detect for all analyzed constituents. • Soil samples were not able to be collected from MW-8 since it had to be drilled with the mast of the drill rig down. GROUNDWATER In summary: ' • Trace levels of BTEX and low levels of TPH-G were detected in MW-1. • MW-2, MW-7 and MW-101 were non-detect for all analyzed constituents. • Fuel oxygenates including MTBE were non-detect in MW-1, MW-2, MW-3, MW-7 and MW-101. I • MW-3 had a trace detection of xylene, otherwise non-detect for all analyzed constituents. • MW-4 had trace levels of BTEX and low levels of both MTBE and TPH-G. • MW-5, MW-6, MW-8 and MW-9 show the presence of MTBE and are non-detect for all ' other analyzed constituents. The highest concentration of MTBE is in MW-6. 3.2 Geology and Field Observations The following section discusses the subjective field observations and geology documented ' during this investigation based on the interpretations of the field geologist. • The geology between 0 and 10 feet bgs is characterized by clay and silt, primarily brown ' in color with varied degrees of plasticity. • A sand layer was between 10 and 30 feet bgs. This layer is primarily tan in color with abundant organic material. The grain size is fine to medium and poorly sorted. ' • A clay layer was encountered between 31 and 42 feet bgs. The clay is blueish-gray in color with moderate plasticity. 3.3 Hydrology of Site On August 22, 2002, the depth to groundwater was measured in the new monitoring wells (MW-7, 8, 9 and 10 1) prior to purging. On September 26, 2002, the depth to groundwater was measured in monitoring wells MW-1 through MW-6. Depths to groundwater in the shallow monitoring wells ranged from a high of 7.64 feet below the top of casing to a low of 9.18 feet below the top of casing. The average depth to water in the shallow wells was 8.49 feet below the top of casing and is consistent with historical data at this site. Groundwater elevation has been updated using the data gathered from the October GPS surveying event. The average groundwater elevation for the 3' quarter event was 1.11 feet below mean sea level (MSL). Previous groundwater elevations recorded at this site have