Laserfiche WebLink
1 <br /> 45 E Harding Way, Stockton, California September 1, 1993 <br /> Chevron USA Products Company Page 5 <br /> extracted from each well by these methods This technique Insures an even sand filter pack, removes <br /> fines, and rehabilrtates the borehole sides The fines are drawn from the well by the bailer until the well <br /> ' water Is visibly clear The development water was stored in a DOT-approved purge water trailer and <br /> transported to the Chevron refinery In Richmond, California for recycling <br /> 3.6 GROUNDWATER MONITORING <br /> On July 23, 1993, the water table in monitoring wells MWA, MW-2, and MW-7 through MW-13 was <br /> gauged from top-of-casing to determine the static level and thickness of any separate-phase <br /> hydrocarbons (SP) Well MW-3 could not be located Wells MWA, MW-2, MW-7 and MW-8 were dry, <br /> and MWA MW-5 and MW-6 were not accessible The water table level was measured using an ORS <br /> ' Environmental Equipment INTERFACE PROBE7m Well Monitoring System, consisting of a dual optical <br /> sensor and electrical conductivity probe, that distinguishes between water and petroleum products No <br /> SP was present in any of the wells monitored The data collected during the July 23 monitoring event <br /> were used to prepare a potentiometnc surface map that depicts an east-northeast groundwater flow <br /> direction at a gradient of approximately 0 003 (Figure 3) <br /> 3.7 GROUNDWATER SAMPLING <br /> 1 <br /> Only wells MW-9 through MW-13 could be sampled because the remaining wells were either dry or not <br /> ' accessible Prior to sampling, the wells were purged of approximately three well casing volumes The <br /> groundwater samples were collected using a Teflon sampler cleaned with an industrial-strength <br /> detergent and distilled water Immediately prior to the collection of the water samples, a distilled water <br /> nnsate blank was collected from the Teflon sampler as a quality control check on the cleanliness of the <br /> ' sampler A tnp/lab blank was also collected for quality control Each sample was acidified, labeled, and <br /> placed on Ice In an Insulated container for delivery to a State-certified laboratory The samples were <br /> ' accompanied by a chain-of-custody manifest during transport and analyzed for TPH-G and BTEX by <br /> EPA methods 5030/8020/8015 Purge water generated during the sampling process was stored in a <br /> DOT-approved purge water trailer and transported to the Chevron refinery in Richmond, California for <br /> ' recycling <br /> J� GROUNDWATER <br /> t3399EAR RPT TECHNOLOGY <br />