ARCHIVED REPORTS XR0006094 - Laserfiche WebLink

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(bgs) An aquitard consisting of silty clay approximately 3 to 4 feet thick separates the silty clayey sand A zone aquifer from the B zone aquifer that is found at approximately 21 feet bgs and is approximately 6 to 7 feet thick The B zone aquifer consists of cleaner moderately sorted fine to coarse sand that shows graded bedding (fine to coarse with depth) Beneath the B zone aquifer is stiff clay that extends from approximately 27 feet bgs to 40 feet bgs The original five monitor wells did not encounter groundwater in the A zone aquifer when initially drilled and sampled. Depth to water measurements taken between 1993 and February 1996 indicate that the A zone aquifer was dry (depth to water greater than 17 feet bgs) MW through MW5 are screened across both the A and B zone aquifers Sometime after February 1996 depth to groundwater measurements indicated that groundwater was in contact with the A zone aquifer, see Table 1 and Figures 8 and 9 The groundwater in the vicinity of the site is semiconfined Groundwater elevation at the site varies from a wet year high of 7 feet bgs (silty clay formation above the A zone) to about 22 - 23 feet bgs (B zone) during the previous drought period Groundwater flow direction in the A zone at the site has generally been to the west since December 1997 The B zone shows a similar flow direction, which would be expected due to the connection between zones at wells MW 1 through MW5 IST O UAIlB')I'IER 2003 SYT E ACTIVITIES TIES Groundwater samples were obtained from all active wells associated with 1876 Country Club Blvd during this quarter (January 31, 2003) As requested by San Joaquin County Health, WEGE and Advanced GeoEnvironmental, Inc (AGE) coordinated to obtain depth to water and groundwater samples on the same date WEGE monitored and sampled wells associated with the Sanchez Property, 1876 Country Club Boulevard and AGE sampled and monitored wells associated with Country Club Food and Fuel, 1856 Country Club Boulevard Figure 3 - Site Base Map has been expanded to show the relative positions of the Country Club Food and Fuel wells to the Sanchez Property wells Field notes from site monitoring and sampling can be found in Appendix A January 6, 2003 Well MW 1 destroyed January 7, 2003 Temporary Piezometers PZ 1 A, PZ 1 B, PZ2A and PZ2B installed January 13-17, 2003 Background measurements of groundwater conditions January 17, 2003 Delivery of 21,000 gallon Baker Tank and 4 water carbon units January 20-25, 2003 Pump test January 31, 2003 Groundwater Samples from all existing Sanchez wells February 4, 2003 Started discharge to sewer, water stored in Baker tank from pump test and quarterly samplings February 5, 2003 USRA constructed impound for holding excavated contaminated soils and sludge February 6, 2003 USRA removed surface of area to be excavated, readied area for excavating 4 QM IST 2003