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CLEARWATER <br /> G R 0 1- P I N C <br /> Envi onmentci Srrv�ces <br /> QUARTERLY GROUNDWATER MONITORING REPORT- SECOND QUARTER 1997 <br /> AND <br /> VAPOR WELL INSTALLATION REPORT <br /> Ruiz Grocery,4491 West Durham Ferry Road,Tracy, CA <br /> May 26, 1997 <br /> BACKGROUND <br /> Two gasoline USTs and dispensers were removed from the site in 1988 Seven monitoring wells (MW-1 <br /> through MW-7), one groundwater recovery well (RW-1), three soil vapor extraction wells (VW-1 <br /> through VW-3), and two air sparge wells (SW-1 and SW-2) have been installed at the site A domestic <br /> well (DW), screened in a deeper water bearing zone, has also been installed at the site The extent of <br /> soil and water contamination has been delineated Pilot testing has been completed and a remedial <br /> action plan prepared based on results <br /> The work presented here was conducted as part of scheduled quarterly groundwater monitoring as <br /> requested by the San Joaquin County Public Health Services / Environmental Health Division <br /> (SJCPHS/EHD) and installation of an additional vapor extraction well to affect vadose and capillary- <br /> fringe contamination in the area between wells VW-3 and MW-1 Clearwater Group, Inc (Clearwater) <br /> submitted a workplan for installation this well dated February 28, 1997, which was approved by the <br /> . SJCPHS/EHD in correspondence dated March 11, 1997 All work was conducted in accordance with <br /> Clearwater's Field Procedures attached <br /> GROUNDWATER MONITORING FIELD ACTIVITIES <br /> Date of field activities 4/22/97 <br /> Wells monitored/sampled MW-1 to MW-7, and the domestic well <br /> Analytes tested TPHg, BTEX, and MTBE <br /> Analytical methods EPA Methods 8015/8020 (modified) <br /> Laboratory American Environmental Network, Inc of Pleasant Hill, CA <br /> Remarks Groundwater samples mistakenly labeled 4/21/97 instead of real <br /> sample date of 4/22/97 <br /> GROUNDWATER MONITORING RESULTS <br /> Depth to water 15 03 to 16 69 feet below ground surface(bgs) <br /> Flow direction/gradient Southwest at 0 0015 ft/ft <br /> SPH - wells/thicknesses <0 01-foot thick sheen in MW-1 & MW-2 <br /> TPHg concentration range <50 gg/L (DW,MW-3,4,5,6, and 7) to 38,000 gg/L (MW-1) <br /> Benzene concentration range <0 5 �tg/L (DW,MW-3,4,5,6,and 7) to 3,400 gg/L (MW-2) <br /> MTBE concentration range <5 0 gg/L (DW,MW-3,4,5, and 6) to 1,200 gg/L (MW-2) <br /> Remarks Groundwater flow direction (to the southwest) is inconsistent with the <br /> flow directions typically observed at the site (to the northwest - <br /> northeast) The change in flow direction may be the result of local <br /> agricultural water uses However, groundwater elevations are <br /> generally consistent with previous observations and the dissolved- <br /> phase plume remains delineated The domestic well remains free of <br /> detectable contamination <br />