WORK PLANS - Laserfiche WebLink

Home Browse Search

' • • Soil Investigation Work Plan Pilkington North America,Inc. ' October 27,2010 Page 2 the excavation, and transported the product to their facility in Newark for recycling. Periodic pumping of ' the excavation resulted in the recovery of approximately 3,000 gallons of diesel and an additional approximately 2,000 gallons of mixed diesel and water. Subsequent efforts to install additional trenches for product recovery were unsuccessful due to unstable soil conditions and the presence of underground ' utilities. Based on the initial diesel release investigation and available Site information, an undetermined volume of diesel fuel was released in the vicinity of the underground product piping. The product piping was subsequently removed from service and abandoned in place by removing the remaining product and filling the piping with cement. The soil beneath the piping was impacted with diesel from approximately ' one foot bgs down to the water table at approximately 13 feet below ground surface. Condor prepared the Soil and Groundwater Investigation Work Plan, dated November 5, 1996 in response to a SJCEHD request to investigate the extent of soil and groundwater impacted by the diesel ' fuel release. On December 3 and 4, 1996, Condor supervised a Geoprobe investigation to evaluate the extent of diesel-impacted soil and groundwater in the vicinity of the supply line. The investigation included the placement of 11 Geoprobe borings around the impacted area (Figure 2, Attachment A). ' Results of the groundwater analyses indicated that dissolved diesel was present in groundwater at all locations sampled and that floating product or a heavy sheen was present at four of the sample locations; GPI, GP4, GP5, and GP6. Soil samples collected from the capillary fringe at a depth of approximately ' ten feet bgs indicated that diesel was present in the soil at the GP 1,GP4, and GP6 boring locations. On June 10 and 11, 1999, six diesel recovery wells (RW-1 through RW-6) were installed in accordance with the Work Plan — Standby Generator Diesel Supply Line/Installation of Product Recovery Wells, dated March 23, 1999. Three monitoring wells were installed concurrently with the recovery well (RW) installations as originally proposed by the Work Plan - Standby Generator Diesel Supply Line/Product Recovery System Installation and Monitoring Well Installation, dated June 23, 1997. The well installations were conducted with the approval of Mr. Philip Isorena of the Regional Water Board. ' An active diesel skimmer was installed at RW-2 on June 18, 1999. Between June 18 and September 29, 1999, approximately 3.1 gallons of diesel were removed from RW-2. Diesel recovery at RW-2 waned to virtually nothing during the final weeks of this period and, consequently, diesel recovery operations at ' RW-2 were discontinued. In the quarterly monitoring report describing the monitoring results and diesel recovery efforts dated ' October 13, 1999, Condor recommended discontinuation of diesel skimming, continued quarterly monitoring of monitoring wells MW-1, MW-2 and MW-3, quarterly monitoring of two facility basement sumps, and quarterly monitoring of natural attenuation parameters at MW-3 and RW-1. In a letter dated May 11, 2000, Mr. Isorena concurred with the proposal to sample the basement sumps but also indicated that the proposed actions were insufficient to address down-gradient and natural attenuation monitoring at the Site. In the letter dated May 31, 2000 Condor responded to Mr. Isorena's comments by indicating that MW-2 would also be monitored for natural attenuation parameters and that down-gradient ' monitoring, in the form of diesel product measurements at RW-2 and sample collection at the facility basement sumps, would continue. In addition, Condor proposed that monthly, intermittent diesel skimming at RW-2 be initiated based on recent diesel thickness measurements indicating that approximately two feet of diesel product had accumulated in the well since diesel recovery operations were discontinued on September 29, 1999. %44�.n ' i1� CONDOR