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y GROUND ZERO ANALYSIS, INC. <br /> 1714 Main Street <br /> Escalon, California 95320-1927 <br /> Telephone: (209)838-9888 no, <br /> Facsimile: (209)838-9883 <br /> June 25, 2007 JUIV 2 62007 <br /> E1VV1RO1U1,9E1VT <br /> San Joaquin County Environmental Health Department PERMIT�SERVhiETN <br /> ICES <br /> 600 East Main Street <br /> Stockton, CA 95202 <br /> Subject: Workplan for Soil Boring Investigation <br /> Knowles Property, 1140-1148 W. Hammer Lane, Stockton, CA <br /> (APN # 077-490-11 & 26) <br /> Dear Mr. Knoll: <br /> We are writing on behalf of Mr. Edwin H. Clock to present a workplan for a Phase II <br /> Environmental Site Assessment at the subject property. The proposed work is intended to <br /> evaluate if subsurface conditions of environmental concern may be present. This work is in <br /> anticipation of the possible sale of the property. The location of the property is shown on Figure <br /> 1. Parcel boundaries and proposed soil boring locations are shown on Figure 2. <br /> Background and Purpose <br /> The parcel (APN # 077-490-27) immediately to the east of the subject parcels formerly operated <br /> as a retail filling station with six underground storage tanks (USTs), associated piping and <br /> dispensers. Soil contamination was discovered in 1987 during UST removal activities. <br /> Subsequently, subsurface investigations determined that groundwater was impacted. Although <br /> excavation removed most contaminated soil in the vadose zone, residual impacted soil may <br /> remain in the zone of historical water table fluctuation (approximately 35- 55 feet below grade). <br /> Groundwater typically has been measured to flow toward the east or southeast, away from the <br /> parcels of interest. Two groundwater monitoring wells (MW6 and MW7) formerly were located <br /> in the southwest and northwest corners of parcel 077-490-27. These wells were free of dissolved <br /> contaminants from 1991 until their destruction in 2001. Soil samples collected at depths of 15 <br /> feet and 50 feet during the drilling of these wells in 1989 were non-detect for all contaminants. <br /> The proposed workscope is intended to verify current soil and groundwater conditions along the <br /> eastern property line where parcel 26 abuts the UST leak site and along the western property line <br /> of parcel 11 which is the hydraulically upgradient point on the property. <br /> G:\GROUNDZE\CLoCKkworkplan.doc <br />