ARCHIVED REPORTS_XR0011815 - Laserfiche WebLink

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On May 5, 1995, a soil vapor extraction system consisting of an R.S.I. SAVE system was installed at the subject site. The vapor extraction system was installed per San Joaquin Valley Unified Air Pollution Control District (SJVUAPCD)Permit conditions. The vapor extraction system consists of an internal combustion engine with catalytic converters mounted on the exhaust. The system was set up such that soil vapors could be extracted from either vapor well VW-1 and/or monitoring well MW-1. The system was started on May 5, 1995, and has operated through October 4, 1995, at which time it was temporarily removed from site. On November 27, 1995, the system was returned to the subject site and restarted. An air sparge system was installed for use in conjunction with the vapor extraction system. The air sparge system consists of a one horse power electric motor which powers a 10-cubic feet per minute (CFM) oil-less compressor. The compressor injects air through an air sparge point located midway between VW-1 and MW-1 (Figure 2). The air sparge system was started on May 31, 1995 and operated intermittently through August 30, 1995, at which time its operation began to coincide with the operation of the R.S.I. system. On April 29, 1997, Apex received permission from the San Joaquin County Environmental Health Division(SJCEHD) to shut down the air sparge and vapor extraction system due to low influent soil vapor concentrations to the vapor extraction system. As of April 29, 1997, the remediation system has extracted a total of 1,730 pounds of total petroleum hydrocarbons (TPH), as gasoline, and 19.9 pounds of benzene. PROPOSED EXCAVTION Apex proposes to remove the loading rack and then excavate out the petroleum impacted soil and groundwater prior to the proposed removal and replacement of the nine USTs (Figure 2). The excavation of the petroleum impacted soil will continue until: the lateral limits shown on Figure 2 have been reached; all petroleum impacted soil registering greater than 100 ppm by HNU photoionization detector screening has been removed- or until the excavation reaches a point that it starts to undermine the building, utilities, or the road. Based on the proposed area of excavation shown on Figure 2, Apex proposes to excavate a maximum 710 cubic yards of soil. The proposed vertical extent of the excavation will be to two feet below groundwater(which was present at ten feet below grade (bg) on August 13, 1997). The anticipated total vertical depth of the proposed excavation will be to 12 feet bg. All fieldwork will be conducted according to Apex Standard Operating Procedures (SOP) included in Appendix A. Soil samples will be screened in the field with the use of an HNU photoionization detector during all excavating activities. If the reading on the HNU is less than 100 parts per million (ppm), then the lateral excavation in that direction will terminate. The lateral limits of the proposed excavation will not exceed the lateral limits shown on Figure 2 or 710 cubic yards.