ARCHIVED REPORTS XR0006114 - Laserfiche WebLink

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PURPOSE-AND-SCOPE- The following report documents the First Quarter 2004 groundwater monitoring Depth to water measurements and groundwater sampling was conducted on January 15, 2004 SITE LOCATION AND DESCRIPTION The site address is 1876 Country Club Blvd , Stockton, CA It is located at the southeast corner of the intersection of Mission Street and Country Club Blvd (Figure 1) The property is located in projected Section 4, TIN, R6E of the MDB&M at approximately five feet above mean sea level The north corner of the property at Country Club Blvd and Mission Road is at N370 58 044' Latitude and WI 210 19 393' Longitude (Delorme sa 7 0) On May ], 2001 Land Surveyors Kjeldsen, Sinnock & Neudeek, Inc surveyed the positions, top of casing and surface elevations of all wells associated with this site, see Appendix B Figures 3 has been revised to this new survey along with Table 1 All associated figures showing site conditions are based on the new Figure 3 The property previously contained two 1000 gallon gasoline Underground Storage Tanks (UST's), product dispensers, and associated underground piping (Figure 3) The UST's, dispensers, and piping were removed from tha site in 1989 Over-excavation of gasoline contaminated soils associated with the USTs and former pump islands occurred during the month of February 2003, removing an estimated 638 tons of gasoline contaminated soils from above and below the water table (maximum depth of excavation 30 feet below surface) The property owner originally installed five onsite monitoring wells Three additional cluster wells and four piezometers were installed to aid in the investigation of soil and groundwater conditions at the site Prior to over-excavation monitor well MWI was destroyed by over drilling and during excavating cluster wells RIA and RIB along with piezometers PZIA, PZ1B, PZ2A and PZ213 were removed by excavating, removing all well materials At the current time the following are the remaining active wells for this site MW2, MW3, MW4, MWS, MW6A, MW6B, MW7A and MW7B LOCAL GEOLOGY AND HY DROGEOLOGY The site is located on surface soils belonging to the Stockton Adobe Clay and Honeycut Clay series They are derived from Recent alluvial fan and floodplain deposits The 40 feet of explored section consisted of clay and silt overlying interbedded lenses of silty and clayey sands below 12 feet This first sandy formation has been designated the A zone aquifer The base of the A zone is at approximately 17 - 18 feet below ground surface (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 3 Sanchez QM 1 ST 2004