ARCHIVED REPORTS_XR0008884 - Laserfiche WebLink

Home Browse Search

' In October 1992, Remediation Services, Inc (RSI) drilled and sampled two soil borings one • boring in the former tank excavation (B-1), and one boring approximately roximatel ten feet north of ' the excavation (the latter was completed as groundwater monitoring well MW-4) The results of the soil samples analyzed indicated that TPH as diesel was present to a depth of 70 feet bgs In the soil boring B-1 (13 mg/Kg TPH as diesel) and to a depth of 60 feet bgs in the soil boring MW-4 (2100 mg/Kg TPH as diesel) None of the chlorinated organic compounds previously detected during the tank excavation sampling were detected in either boring (Figures 4 and 5) In February 1993, additional soil investigation conducted by RSI included sampling and characterization of four soil borings (B-101 through B-104) drilled to depths of 75 feet bgs (Figure 2) TPH as diesel was detected at a maximum concentration of 1 i mg/Kg at a depth of 55 feet bgs in boring B-103 (Figures 4 and 5) In December of 1993, RSI installed two additional groundwater monitoring wells (MW-5 and MW-6) Monitoring wells MW-5 and MW-6 are screened between 70 and 90 feet bgs, and together with MW-4 were being monitored and sampled on a quarterly basis for TPH as diesel and BTEX by BSK and Associates (Figures 4 and 5) In May 1995, an interim corrective action consisting of the excavation of approximately 330 cubic yards of petroleum-impacted soil from the former UST pit and vicinity was performed by rr Figures 2 to 6 present the lateral and vertical extent of the excavation The native soil in the vicinity of the previously removed tanks appeared to be impacted primarily with TPH as diesel Associated aromatic hydrocarbons (toluene, ethyl benzene and total xylenes) were also present in soil at very low concentrations No detectable concentrations of TPH as gasoline or benzene were detected. Tins suggested that there was no gasoline-impacted soil in the vicinity of the tank pit excavation A vapor observation point was constructed at the base of the excavation The excavation was subsequently backfilled with clean imported fill material and capped. In August 1995, rr drilled and sampled two soil borings (SB-1 and SB-2, both to 64 5 feet bgs) to assess site conditions and provide a framework for recommending further action (Figure 2 and 6) Sample analysis included chemical, bioassay, and geotechnical testing Results indicated that there has not been further lateral migration of TPH as diesel or BTEX compounds, and that TPH as diesel concentrations have decreased over tune Bioassessment tests suggested that intrinsic bioremediation activity is occurring at the site MZ4&13-97/VDBF/'97-0009 BK 2