ARCHIVED REPORTS XR0006997 - Laserfiche WebLink

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approximately 2 feet between September 18, 1997 and December 31, 1997 Groundwater elevation contours estimated using the depth-to-water measureme,irts collected on December 31, 1997 indicated that groundwater flow at the site was generally consistent with the estimated flow on September 18, 1997 On March 27, 1998, Condor personnel were on site to conduct quarterly groundwater monitoring Laboratory analyses of groundwater samples collected from the site monitor wells indicated that BTEX, TPH-G and the selected gasoline oxygenates/additives were not detected at or above the laboratory reported detection limits in the sample collected from MW-I Ethanol, tertiary-butanol, DIPE, ETBE, and TAME were not detected at or above the laboratory reported detection limits in any of the groundwater samples Detection limits for the analysis of the samples collected from MW-2 and MW-3 were i aised, however, due to relatively high concentrations of M 1 BI in the samples collected from those wells (as described below) Benzene and TPH-G were not detected at or above raised detection limits and low concentrations of TEX constituents were detected in the sample collected from MW-2 M t BE was detected at 1 10,000 pg/l in the MW-2 sample B FCX and TPH-G were not detected at or above the laboratory reported detection limits in the sample collected from MW-3 MTBE was detected at 1,900 4g/1 in the MW-3 sample TPH-G and BTEX constituents were detected in the sample collected from MW-4 MTBE was not detected at or above the laboratory reported detection limit in the MW-4 sample. No floating product, sheen, or petroleum hydrocarbon odor was noted in the monitor wells Laboratory analytical results of the groundwater samples for the first quarter, 1998, monitoring event were generally corisistcrit with historical quarterly groundwater analytical data MTBE concentrations in samples from MW-2, however, increased by more than two orders of magnitude during the three sampling events conducted at the site IGroundwater elevation measurements collected at the site on March 27, 1998, indicated that the average depth to groundwater was approximately 5 feet bgs l lie average depth to water at the site increased by approximately l foot bet%%een December 31, 1997 and March 27, 1998 Groundwater elevation contours estimated using the depth-to-water mcasuremcntS collected oin March 27, 1998, iridicatcd that groundwater gradient at the site is generally consistent NVrth the cstimatcd gradient on Scptcmber 18, 1997 and December 3 1, 1997 In a telf.plione conversation on March 23, 1998, Mr Ronald Rowe of the San Joaquin ( ounty Public Health Services/l,nvironmcntal Health Department (PI iS/EfID) indicated that based on his review of the report dated December 11, 1997 (referenced above), he was requesting that quarterly groundwater monitoring continue at the site Furthermore, he requested that a work plan be prepared for conducting quarterly surface water sampling and additional investigation of the gasoline oxygenate/additive plume to the east of monitor well MW-2 Condor subsequently prepared the Work Plan - Additional.Soil and Groundwater Investigation/Surfuce Water Samphng dated May 27 1998 In a faxed note dated June 1, 1998, Mr Rowe approved the work plan with the stipulation that a work plan addendum be prepared describing installation of additional borings to those proposed in the work plan and grab sampling of the Herman & Helen's Marina drinking water source Condor subsequently prepared the Work Plan Addendum, dated July 9, 1998 In a tax dated July 27, 1998, Mr Ron Rowe approved the work plan addendum adding that both the facility pre-treated drinking water and the post- treatment water should be sampled and analyzed by appropriate methods