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ENVIRONMENTAL HEALTHI)EPARTMENT
<br /> SAN JOAQUIN COUNTY
<br /> Donna K. Heron, R.E.H.S. Unit Supervisors
<br /> Director 304 East Weber Avenue,Third Floor Carl Borgman,R.E.H.S.
<br /> �,•-� `• AI Olsen, R.E.H.S. Stockton,California 95202-2708 Mike Huggins,R.E.H.S., R.D.I.
<br /> Program Manager Telephone: (209)468-3420 Douglas W.Wilson,R.E.H.S.
<br /> Laurie A. Cotulla, R.E.H.S. Margaret Lagorio,R.E.H.S.
<br /> Program Manager Fax: (209)464-0138 Robert McClellan, R.E.H.S.
<br /> Website:www.sjgov.org/ehd/ Jeff Carruesco,R.E.H.S.
<br /> D CHARLES SKOBRAK DEC 2 7 2005
<br /> 9947 EAST HIGHWAY 26
<br /> STOCKTON CA 95215
<br /> RE: Larry's Auto SITE CODE: 1122
<br /> 308 North Grant Street RO: 194
<br /> Stockton, CA 95202
<br /> San Joaquin County Environmental Health Department (EHD) has reviewed Soil Vapor Extraction
<br /> Pilot Test dated November 30, 2005, and Groundwater Monitoring Schedule dated December 5,
<br /> 2005, submitted by Advanced GeoEnviromnental, Inc. (AGE)on your behalf.
<br /> AGE proposes to perform a soil vapor extraction (SVE) pilot test to determine whether SVE is a
<br /> feasible remediation method for this site. The pilot test will be conducted for approximately eight
<br /> to ten hours by using an internal-combustion unit to apply a vacuum to vapor well VW5A, screened
<br /> at 13 to 23 feet below ground surface(bgs), and VW5B, screened at 26.5 to 41.5 feet bgs. EHD has
<br /> inferred that the vacuum will be applied to both VW5A and VW5B, simultaneously. Instead, EHD
<br /> recommends that the vacuum be applied to each vapor well separately to monitor the sphere of
<br /> influence for each vapor well and the lithology in its screened interval. AGE also proposes to
<br /> measure the vacuum's influence at vapor wells VW2 through VW5 and unidentified monitoring
<br /> wells. Recent data show that groundwater is currently at approximately 34.5 feet bgs, and as all
<br /> five monitoring wells are screened at depths of 40 feet and deeper,none of the monitoring wells can
<br /> be used to measure the vacuum's influence. Only vapor wells VW2A, screened at 25 to 40 feet
<br /> bgs, possibly VW4 screened at 34 to 54 feet bgs, and water extraction well EWl, screened at 30 to
<br /> 50 feet bgs, can be used to measure the vacuum's influence. Also, AGE proposes to collect four air
<br /> samples at approximately two-hour intervals. Instead, EHD recommends that eight vapor samples
<br /> be collected, four samples from VW5A and four samples from VW5B. In addition to analyzing the
<br /> vapor samples for total petroleum hydrocarbons as gasoline(TPH-g),TPH-diesel; benzene,toluene,
<br /> ethyl benzene, and total xylenes (BTEX); methyl tertiary-butyl ether (MTBE), ethyl tertiary-butyl
<br /> ether (ETRE), tertiary-amyl methyl ether (TAME), tertiary butyl alcohol (TBA), and di-isopropyl
<br /> ether (RIPE), also analyze the air samples for 1,2-dichloroethane (1,2-DCA), and 1,2-
<br /> dibromoethane (EDB). EHD approves the SVE pilot test. Please complete this fieldwork by
<br /> February 28,2006.
<br /> AGE proposes a reduction of sampling vapor wells onsite in Groundwater Monitoring Schedule.
<br /> Instead of collecting quarterly groundwater samples from vapor wells VW-2B, VW-3, VW-4, VW-
<br /> 5B, and VW-5C, these wells will be sampled annually during the fourth quarter (October,
<br /> November, or December) and results will be reported for the entire suite of compounds by
<br /> Environmental Protection Agency (EPA) SW-846 Method 8260. AGE also proposes that
<br /> monitoring wells MW-1, MW-2, MW-3, MW4, and MW-7 be analyzed for the entire suite of EPA
<br /> SW-846 Method 8260 compounds during the fourth quarter, and analyzed for TPH-g, TPH-diesel,
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