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California RVonal Water Quality C -ntrol Board .: <br /> Central Valley Region <br /> Robert Schneider,Chair <br /> Alan C.Lloyd Ph.D Arnold Schwarzenegger <br /> Secretary for 11020 Sun Center Drive#200 Rancho Cordova,CA 95670-6114(916)464-3291 Governor <br /> Environmental http://www.swrcb.ca.gov/rwgcb5 <br /> Protection <br /> TO: Brian Newman <br /> Supervising Water Resources Control Engineer <br /> UST Program Manager <br /> UST Case Files <br /> FROM: James Barton `�ANU <br /> Engineering Geologist <br /> DATE: 16 February 2005 - <br /> SUBJECT.• RESPONSE TO PETITION, CHAPINBROTHERS INVESTMENTS,INC., <br /> 1766 MONTE DL4BL0 AVENUE,STOCKTON,SAN JOAQUIN COUNTY <br /> I reviewed the file, including the 10 August 2004 Closure Report(Report)submitted by ATC Associates Inc., <br /> the 23 November 2004 Petition for State Water Resources Control Board Review of Chapin Brothers Investment <br /> Inc.Property at 1766 Monte Diablo Avenue, Stockton, California(Petition),the 5 January 2005 letter from the <br /> State Water Resources Control Board(SWRCB)to San Joaquin County Environmental Health Department <br /> (SJCEHD)concerning notification of the Petition, and the two SJCEHD response letters dated <br /> 14 and 25 January 2005. In their 14 January 2005 letter, SJCEHD 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 Underground Storage Tanks (USTs) cleanup is currently handled by SJCEHD under their authority pursuant <br /> to the Local Oversight 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 from Tom Blanchard, 1975-85. USTs removals by Shell Oil Company included one 8,000-gallon <br /> gasoline UST in 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 pending sale for the decommissioned service station. On 4 August 1993,one 550-gallon waste oil,three <br /> 1,000-gallon gasoline,two 4,000-gallon gasoline,and two 8,000-gallon USTs were removed by the Petitioner. <br /> Subsequently soil contamination was found from 15 to 25 feet bgs, extending laterally offsite under Buena Vista <br /> Ave to the west(see attached map). Depth to groundwater was reported as approximately 21.5 feet bgs at the time <br /> of the USTs removal. Up to three feet of free product was reported in monitoring well MW-1, screened 17 to <br /> 30 feet bgs, on 6 August 1993. SJCEHD requested free product be removed from MW-1,which occurred on <br /> 16 August, 19 August, and 2 September of 1993, and then once quarterly until no free product was detected in <br /> March 1996. Three 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 /> December 1993. While SVE and air sparging(AS)tests were conducted during June 1994 and January 1995, <br /> actual operation of the AS system and SVE system did not begin until March and April 1997,respectively. By that <br /> time the depth to groundwater had risen from 20 feet bgs to 15 feet bgs into a silty zone, limiting the effectiveness <br /> California Environmental Protection Agency <br /> �d Recycled Paper <br />