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1 v <br /> A S S O C I A T E S I N C <br /> l <br /> The wells were located on the map according to "well location" descnptlon provided on the well <br /> ' construction logs Available well construction details are included on the well logs included in <br /> Appendix D <br /> The closest well is approximately 300 feet north of the site on North Walnut Avenue, located in <br /> the downgradient direction This well is identified as Well 4 (labeled Well No 4 on the map) and <br /> is in operation by the City of Ripon The well is 257 feet deep and the casing is 14 inches in <br /> 1 diameter to 150 feet where it is reduced to 10 inches in diameter Extracted water is treated with <br /> a sand filter and granular activated carbon <br /> 1 Approximately 1,800 feet east of the site at 334 East Main Street, the logs indicated four <br /> monitoring wells are present at a gasoline service station (labeled Well No l on the map) These <br /> ' wells are located hydrologically cross gradient from the site and are used for monitoring purposes <br /> only <br /> Approximately 1,800 feet south of the site near Fourth Street and Elm Street is a municipal well <br /> identified as Well 6 (labeled Well No 3 on the map) The well is 340 feet deep, 16 inches in <br /> diameter, and screened from 84 feet to 338 feet below ground surface A sanitary seal is present <br /> from the surface to 54 feet bgs The well is upgradient hydrologically from the site <br /> Three other wells were identified within 2,000-foot radius during the survey Each well has been <br /> ' properly abandoned <br /> 6.0 CONCLUSIONS/RECOMMENDATIONS <br /> 1 Based on the analytical results and field observations, TPHg, BTEX or oxygenate fuel additives <br /> were not detected in soil and groundwater along the perimeter of the-site and at depth beneath the <br /> former UST The estimated lateral extent of TPHg in soil is generally limited to the vicinity of the <br /> former USTs The estimated lateral extent of TPHg in groundwater is limited to the vicinity of <br /> the site The estimated vertical extent of impacted groundwater appears to be limited to the <br /> 1 shallow aquifer and is present at depths less than 45 feet bgs <br /> ' The well survey revealed that the City of Ripon Well No 4 is approximately 300 feet north of the <br /> site on North Walnut Avenue The well is 257 feet deep but no other information on perforations <br /> or a sanitary seal was provided Extracted water is treated with a sand filter and granular <br /> activated carbon so if the contaminant plume were to migrate toward the well, it would not be an <br /> immediate threat to human health <br /> ATC recommends continued quarterly groundwater monitoring with analysis of samples for <br /> 1 TPHg and BTEX ATC also recommends performing a groundwater extraction pilot test to <br /> evaluate this alternative for remediation of the site and to prevent future off-site migration of the <br /> plume <br /> w\149811reponslAdd_Inv doc 5 <br />