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Sent By: REGIONAL BOARD ANNEX; 916 2553164; Feb-24-r 10:47; Page 3
<br /> Ca, ifornia R innnl Water Quality (I. )>ntrol Board
<br /> I Central Valley Region
<br /> Robert Schneider,Chair
<br /> Alan C.t.tnyd Ph.D Arnold SChwarcenegger
<br /> Secretaryfoe 11020 Sun Center urivc#200 Rancho Cordova,CA 95670.6114(916)464-3291 0avernur
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<br /> Protection
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<br /> TO: BrianNewman
<br /> Supervising Water Resources Control Engineer
<br /> UST Program Manager
<br /> UST Case F iles --
<br /> FROM: James Barton
<br /> Engineering(ecologist
<br /> DATE: 16 February 2005
<br /> SUBJECT- ESPONSE TO PETITION, CHAPIN BROTHERS INVESTMENTS,INC.,
<br /> 766 MONTE DIABLO AVENUE,STOCKTON,SAN JOAQUIN COUNTY
<br /> I reviewed the Ille, including the 10 August 2004 Closure Report(Report)submitted by ATC Associates Tnc.,
<br /> the 23 Novem r 2004 Petition for,State Water Resources Control Board Review of Chapin Brothers Investment
<br /> Inc. Properly a,1766 Monte Diablo Avenue, Stockton, California(Petition),the 5 January 2005 letter from the
<br /> State Water Re ources Control Board(SWRCB)to San Joaquin County Environmental Health Department
<br /> (SJCEiID)con erning notification of the Petition,and the two SJCEHD response letters dated
<br /> 14 and 25 Janu iry 2005. In their I4 January 2005 letter, SJCLTAT) requested that Regional Board staff provide
<br /> comments to the Petition. By email dated 25 January 2005, SWRCB also requested our comments by
<br /> 18 February 2005.
<br /> Background-
<br /> This Undergro nd Storage Tanks(USTs) cleanup is currently handled by SJCEHD under their authority pursuant
<br /> to the Local O ersight Program contract with SWRCB. The service station was built by Shell Oil Company in the
<br /> 1930's. Prior to acquiring the site in 1985,the Petitioner subleased the service station, from Shell Oil Company,
<br /> 1941-75 and f m Tom Blanchard, 1975-85. UST's removals by Shell Oil Company included ono 8,000-gallon
<br /> gasoline UST i 1 1963 and one 8,000-gallon gasoline UST in 1972. One groundwater monitoring well(MW-1)
<br /> screened from 17 to 30 feet below ground surface(bgs)was installed in December 1990,to assess groundwater
<br /> before a pendit g sale for the decommissioned service station. On 4 August 1993,one 550-gallon waste oil, three
<br /> 1,000-gallon g soline, two 4,000-gallon gasoline,and two 8,000-gallon USTs were removed by the Petitioner.
<br /> Subsequently s it contamination was found from 15 to 25 feet bgs,extending laterally offsite under Buena Vista
<br /> Ave to the wed (see attached ural)). Deptli to gruundwat.er was reported as approximately 21.5 feet bgs at the time
<br /> of the U STs rei noval. 11p to three fleet of tree product was reported in monitoring well MW-1, screened 17 to
<br /> 30 feet bgs,on 6 August 1993. SJCEI ID requested free product be removed from MWA,which occurred on
<br /> 16 August, 19 'kugust,and 2 September of 1993,and then once quarterly until no free product was detected in
<br /> March 1996. 1 hree additional first water groundwater monitoring wells(MW-2 to MW-4), screened from 15 to
<br /> 35 feet bgs,and one soil vapor extraction(SVE) well(VW-1),screened 5 to 20 feet bgs,were installed in
<br /> Decembcr 19^ `x'!i',� `,rr' a yI "_S)tt:ts were col�ducted during June 1994 and January 1995,
<br /> actual operation of the AS system and SVE system did not begin until March and April 1997,respwively. By that
<br /> time the depth:o groundwater had risen from 20 feet bgs to IS feet hg.,;into a silty zone, limiting the effectiveness
<br /> California Environmental Protection Agency
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