ARCHIVED REPORTS_XR0007232 - Laserfiche WebLink

Home Browse Search

sand, which extends to 25 or 30 feet in all borings A relatively widespread clay or clayey silt bed is present from 35 to 40 feet, but below 30 feet the dominant lithology is sand in all borings The base occurs at 78 feet in MW-5 Greenish gray silt is present to the bottom of the boring at 85 feet The depth to groundwater ranged from 72 to 73 feet in January 1994 The calculated elevation of this surface was anomalously low in MW-5 Therefore, the depths to groundwater were remeasured in February 1994 The elevation of water in MW-5 was again anomalously low. The gradient averages apprommately 0 003 ft/ft directed S 10° W for both monitoring events This gradient is more shallow than the previous gradient of 0 05 ft/ft directed westward (November 1992) TPas gasoline asoline was detected in the water sample from MW-2 at 85 ppb Benzene was detected in samples from MW-2 and MW-6 Toluene was detected in MW-2 and MW-5 3.0 PROCEDURES 3.1 Monitoring Well Purge Procedures On May 4, 1994, the water levels in all six wells were measured relative to the top of the casing using a Solinst water level meter (Table 1) After water levels were measured, a PVC bailer was used to purge approximately 4 to 6 gallons (minimum of three well volummes) of water from each well 'Temperature, pH and conductivity were measured at one-gallon intervals Stabilization data and field logs are included in Appendix A The purge water was stored in 55-gallon drums on-site 3.2 Groundwater Sample Collection and Analysis Water samples were collected from each well using new disposable plastic bailers Three 40- ml EPA vials of water were collected from each well and transported in a chilled container to McCampbell Analytical, Inc in Pacheco (MAI) Each sample was analyzed for total petroleum hydrocarbons (TPH) as gasoline and purgeable aromatics (BTE&X) in accordance with EPA methods 8015m and 602 Laboratory reports and chain-of-custody forms are presented in Appendix B 3.3 Soil Disposal On May 11, 1994, 17 drums of soil were removed from the site and transported to 11490 North Alpine Road The drums contained auger returns from bonngs MW-5, MW-6, B-7 ' and B-8 Analytical results from these borings indicated that the soil was not impacted by petroleum hydrocarbons The soil was spread next to the driveway near the residence at 11490 North Alpine Road —1-P-1 wee„S..Is. 5 L-W-1d Bft o awes-M40-S