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ENVIRONMENTAL HEALTH DEPARTMENT
<br /> " SAN JOAQUIN COUNTY
<br /> Unit Supervisors
<br /> Donna K.Heran,R.E.H.S. Carl Borgman,R.E.H.S.
<br /> __. 304 East Weber Avenue, Third Floor
<br /> DirectorMike Huggins,R.E.H.S.,R.D.I.
<br /> "1 At Olsen,R.E.H.S. Stockton, California 95202-2708 Douglas W.Wilson,R.E.H.S.
<br /> Program Manager Telephone: (209) 468-3420 Margaret Lagorio,R.E.H.S.
<br /> 9 i'F Oaf` Laurie A.Cotulla,R.E.H.S. Robert McClellan,R.E.H.S.
<br /> Program Manager Fax: (209) 464-0138 Mark Barcellos,R.E.H.S.
<br /> KAREN PETRYNA AUG 1 ZOO4
<br /> EQUILON ENTERPRISES LLC
<br /> P O BOX 7869
<br /> BURBANK CA 91510-7869
<br /> SINGH, SUKH C & PERMINDER K
<br /> 880 VICTOR RD
<br /> LODI, CA 95240
<br /> RE: SHELL SERVICE STATION SITE CODE: 1746
<br /> 880 VICTOR ROAD
<br /> LODI CA 95240
<br /> Three off-site monitoring wells MW-8,M�V-9,M%V-10,and one on-site monitoring well MW-11 were
<br /> installed in July 2003 in an effort to define the lateral and vertical extent of the contamination plume.
<br /> MW-8 thm MW-10 were screened from 45 feet to 60 feet below surface grade (bsg),and MW-11 was
<br /> screened from 90 feet to 100 feet bsg. The two proposed off-site wells MW-12 and M%V-13 east of
<br /> the property have not been installed to date due to denial of the access by the property owner(Teresi
<br /> Trucking). Four quarters of sampling events have been conducted. San Joaquin County
<br /> Environmental Health Department(EHD) has reviewed the latest quarterly monitoring report
<br /> Groundwater Monitoring Report—Second Quarter 2004 dated August 4,2004 prepared by Cambria
<br /> Environmental Technology,Inc. (Cambria). Analytical results of methyl tert-butyl ether(MTBE)in
<br /> the groundwater samples from the on-site deep well M%V-11 were 3.0 micrograms per liter(ug/1)in
<br /> -detect at less than 0.50 ug/1 in both February and
<br /> August 2003,2.4 ug/l in November 2003,and non
<br /> June 2004 samples. Results of other analytes including Total petroleum hydrocarbons as gasoline,
<br /> benzene,toluene,ethyl benzene,xylenes,di-isopropyl ether (RIPE), ethyl tertiary butyl ether(ETBE),
<br /> tertiary amyl methyl ether(TAME),and tertiary butyl alcohol(TBA) of MW-8 dirt MW-11
<br /> groundwater samples for all four sampling events were all non-detect. Concentrations of TBA in the
<br /> highest impacted monitoring points MW-4 and P-1 continued to increase and MTBE continued to
<br /> decrease. Analytical results of TBA in June 2004 rose from 54,000 ug/1 to 77,000 ug/I in Tule/-4,and
<br /> from 160,000 ug/I to 240,000 ug/I in P-1;in contrast,analytical results of MTBE in June 2004
<br /> dropped from 2,800 ug/l to 1,600 ug/l in MW-4,and from 13,000 ug/l to 6,700 ug/l in P-1.
<br /> EHD has been most concerned with high concentration of oxygenates at the site,and the possible
<br /> conversion of MTBE in groundwater to its biodegradation product TBA. TBA is a compound that
<br /> is potentially more difficult to remediate in groundwater than both MTBE and benzene due to
<br /> TBA's miscible solubility and significantly lower Henry's Constant(the ability to volatilize from
<br /> dissolved phase). As a result,Equilon Enterprises (Equilon)was directed on multiple occasions,first
<br /> in a letter dated March 22,2002,and subsequently in a letter dated March 21,2003,to submit and
<br /> implement an interim remediation work plan that will continuously reduce the oxygenate mass,
<br /> hydraulically control the spread of the plume,and prevent further degradation of groundwater. In a
<br /> Response Letter dated May 2,2003,Equilon challenged the EHD directive to implement a continuous
<br /> remediation system,and proposed implementing 3 short-termed five-day extraction events before
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