ARCHIVED REPORTS XR0004682 - Laserfiche WebLink

Home Browse Search

Ground Water Aquifer Pumping Test Report - May 2001 Former CHASE CHEVROLET Madison Facility 423 North Madison Avenue, Stockton, California 1.0. INTRODUCTION ' Advanced GeoEnvironmental,Inc (AGE)has preparedthis groundwater aquifer ort for 423 North Madison Avenue, Stockton, California The site setting is Illustrated onFggure lintestes e structures and monitoring well locations are depicted on Figure 2 Tliis report is prepared in 1 accordance with guidelines established by the California Regional Water Quality Control Board - Central Valley Division for investigation of underground storage tank (UST) sites ' The objective of the work was to obtain general groundwater aquifer characteristics and to evaluate aquifer response to ground water extraction at a constant pumping rate Based on previous ' investigations, AGE has identified two potential hydrogeologic units informally identified as the upper and lower water zones These two zones are separated by approximately 10 to 15 feet of clay and silty clay generally lying between 35 feet and 50 feet bsg It is not known how effectively the ' intervening fine grained interval hydrologically separates the informal hydrogeologic units though some contarnination has migrated through or around thein. Site background information was summarized in Revised Corrective Action Plan - February 1997, Site investigation Repo -rt LIST' ' No 8, dated 10 February 1998 and Quarterly Report - August 1998, dated 08 December 1998, prepared by AGE 1 'f 2.0. GROUND WATER AQUIFER PUMPING TEST ' On 24 May 2001,a ground water aquifer pumping test was performed at the site to assess the general ground water aquifer characteristics and to assess aquifer response to ground water extraction at a constant pumping rate Monitoring wells screened in the upper water zone (EW-2, MW-19A, ' MW-20A and MW-21A) and lower water zones (MW-19B, MW-20B and MW-21B) were utilized as observation wells, purged ground water was containerized in an on-site 6,500-gallon poly tank (Baker tank) Table 1 suns narizes well construction specifications 1 21 8-HOUR AQUIFER PUMPING TEST The pumping test consisted of extracting upper zone ground water from extraction well EW-1 at a ' rate of 6 gprn utilizing a 4-inch diameter submersible Grundfos Redi-flo initially extracted at 5 for a period of 45 minutes, pump Ground water was when it was determmed bm y field observations that the aquifer could support he was igher Pur toui6 gpm pip g ate Advanced GeaF,nvironnuntai,Inc v r ' s l P