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Workplan Addemdum Letter for a Limited Subsurface Site Investigation
<br /> Moore Petroleum, 5491 F Street,Banta,California
<br /> Page 2
<br /> monitoring well MW-1. The system was started on May 5, 1995, and operated through October
<br /> 4, 1995, at which time it was temporarily removed from the site. On November 27, 1995, the
<br /> system was returned to the subject site and restarted.
<br /> On May 31, 1995 an air sparge system was started and operated intermittently through August
<br /> 30, 1995, at which time its operation began to coincide with the operation of the R.S.I. system.
<br /> The air sparge system was installed for use in conjunction with the SVE system. The air sparge
<br /> system consisted of a one-horse power electric motor which powers a 10-cubic feet per minute
<br /> (cfm) oil-less compressor. The compressor injected air through an air sparge point located
<br /> midway between VEW-1 and MW-1 (Figure 2). The air sparge system was started on May 31,
<br /> 1995 and operated intermittently through August 30, 1995,
<br /> On April 29, 1997, Apex received permission from the SJCEHD to shut down the air sparge and
<br /> vapor extraction system due to low influent soil vapor concentrations to the SVE system. As of.
<br /> April 29, 1997, the remediation system had extracted a total of 1,730 pounds of total petroleum
<br /> hydrocarbons (TPH),.as gasoline, and 19.9 pounds of benzene.
<br /> On September 10, 1997 Apex submitted the report titled, Over Excavation & Groundwater
<br /> Removal Workplan, proposing over excavation, de-watering and sampling of the bulk loading
<br /> rack and tank basins during the removal of nine underground storage tanks (UST).
<br /> On August 17, 1998 and September 8, 1998, Apex supervised the removal of two 350 gallon
<br /> USTs, T-8 and T-9 (kerosene and cleaning solvent, respectively). Also, seven 10,000 gallon
<br /> USTs were removed on September 8, 1998. Results of the UST removal were documented by
<br /> Apex in the report titled, Tank Closure Results and Recommendations Report, dated December
<br /> 23, 1998.
<br /> On December 23, 1998, Apex submitted a report titled, Tank Closure-Results and
<br /> Recommendations Report, giving the results of all soil and water sampling conducted since the
<br /> removal of T-9. Following the removal of T-9, soil was over excavated and an exploratory
<br /> trench was dug. Apex collected two soil samples and one groundwater sample from the over-
<br /> excavation and exploratory trench. One soil sample was collected from beneath T-8. After the
<br /> removal of the seven 10,000 gallon USTs, Apex collected four soil samples and one groundwater
<br /> sample from the tank pit. Apex then collected six additional soil samples and two additional
<br /> water samples from beneath the tank basin. Nine soil samples from the area beneath the former
<br /> bulk loading rack were submitted for analysis.
<br /> On April 8 and 9, 1999, Apex personnel supervised the advancement of eight soil borings at the
<br /> subject property. The results of all soil and water sampling were documented in the report titled,
<br /> Results Report for Subsurface Investigation and Second Quarter 1999 Groundwater Monitoring,
<br /> dated June 1, 1999.
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