ARCHIVED REPORTS_XR0002126 - Laserfiche WebLink

Home Browse Search

Sod Excaysaon Resuft Ripon 909 Hamner Lane Stoddon Caldomia Five groundwater monitoring wells (MW-1 through MW-5) were drilled in 1986 and 1987 '. In 1990, wells MW-6, MW-7, and MW-8 were drilled in the vicinity of wells MW-3, MW-4, and MW-5, respectively, because the latter went dry The wells have been sampled periodically since 1986 Groundwater has varied from a depth of approximately 47 feet in 1987 to approximately 60 feet in September 1992 None of the groundwater samples from the wells have contained detectable petroleum hydrocarbon concentrations since 1991 Wells MW-3, MW-4, and MW-7 could not be located during the most recent groundwater sampling event in June 1993 Depth to groundwater varied from 54 62 to 55 98 in June 1993 EA Engineering submitted a workplan in November 1992 to drill and sample three soil borings to confirm soil remediation The San Joaquin County Environmental Health Department (County) approved the workplan, and agreed to recommend site closure to the Central Valley Regional Water Quality Control Board if the boring soil samples confirm remediation Aegis drilled and sampled the borings in June 1993 Petroleum hydrocarbons were only detected in one boring (SB-9 on Figure 2) at depths ranging from 16 to 36 feet below grade The highest concentrations were noted at 21 feet below grade This work, and all previous site soil and groundwater sampling results, was documented in Aegis' 'Remediation Confirmation Sampling Results and Closure Recommendation" report, dated September 9, 1993 In November 1993, Aegis submitted a workplan to excavate hydrocarbon-impacted soils • remaining in the vicinity of soli boring SB-9 PROCEDURES AND RESULTS On November 22, 1993, Aegis supervised the excavation of remaining soils impacted by residual petroleum hydrocarbons in the area around SB-9 The work was conducted according to Aegis' County-approved workplan and health & safety plan, dated November 9, 1993, and the standard operating procedures included as Attachment 1 Laboratory reports and chain-of-custody forms are included as Attachment 2 Mr Harlin Knoll of San Joaquin County observed the final excavation extent and soil sampling results The extent of the excavation was determined by inspecting soil samples for evidence of petroleum hydrocarbons by sight, odor, and with a photoionization detector These observations were verified by analyzing selected samples for total petroleum hydrocarbons (TPH) as gasoline, benzene, ethylbenzene, toluene, and total xylenes The samples were analyzed on site with a state-certified mobile laboratory An estimated total of 180 to 200 cubic yards of soil were removed and stockpiled on site, on and under plastic sheeting, pending waste characterization and disposal arrangements The soil was characterized as non-hazardous waste and hauled to Laidlaw's Class II disposal facility in Buttonwillow, California Disposal documentation is included as Attachment 3 93 005A FZER 2