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ESA Environmental <br /> Science <br /> Associate; t1` 1 E D D) <br /> JUL 3 0 2001 <br /> July 26, 2001 <br /> IiR,0N AE"N r �r�r��r�� <br /> EN <br /> PERM IT/SERVIU ES <br /> Ms. Dot Lofstrom,R.G. <br /> San Joaquin County Public Health Services <br /> Environmental Health Division <br /> 304 East Weber Street <br /> Stockton, California 95202 <br /> I <br /> Subject: Proposed Groundwater Monitoring Well Locations <br /> Former Underground.Storage Tank:Site, <br /> University of the Pacific(UOP)Physical.Plant <br /> 1081 W.Mendocino Avenue, Stockton,California <br /> Dear Ms. Lofstrom: I <br /> I <br /> Environmental Science Associates (ESA)has prepared the attached map showing the proposed locations of <br /> four groundwater monitoring wells at the site referenced above. The purpose of the proposed wells is to <br /> further delineate the extent of methyl tertiary-butyl ether(MTBE) in soil and groundwater. MTBE was first <br /> detected at the bottom of the former UST excavation following the removal of a 4,000-gallon gasoline tank <br /> in April 2000. Concentrations of petroleum hydrocarbons(gasoline) were either not detected or at very low <br /> concentrations. The July 2000 soil and groundwater investigation detected concentrations of up to 1,200 <br /> micrograms per liter(µg(L)MTBE in boring TP-4, and 160 gg/L in boring TP-5. ESA's subsequent soil and <br /> groundwater investigation in January 2001 did not detect concentrations of MTBE in 10 borings installed <br /> outside of the former tank pit. <br /> I <br /> Based upon the results of previous investigations and in response to San Joaquin County Environmental <br /> Health Division (SJCEHD) well installation request dated April 25, 2001,ESA is proposing to install four <br /> groundwater monitoring wells at the locations shown on the attached map. Well locations were selected to <br /> monitor potential MTBE concentrations upgradient,downgradient,and crossgradient of the former tank pit. <br /> An additional well is proposed near boring TP-4 to monitor previously detected concentrations of MTBE in. <br /> the former tank pit. ESA is submitting the proposed well location map in order to expedite future SJCEHD <br /> —review of"the weli`nstall`ation woikplan. <br /> I <br /> We have appreciated your assistance and the help we have received from your department throughout the <br /> course of this project. Following SJCEHD approval of well locations,ESA will submit a well installation <br /> workplan describing the proposed field work, well specifications, and field methodologies. If you require <br /> additional information or have questions, please call Ms. Jennifer Schulte or me at(415) 896.5900. <br /> Sincerely,. <br /> Peter B. Hudson, G. <br /> cc: John Forsythe,ESA Sacramento <br /> Crystal Stech,ESA Sacramento <br /> 225 Bush Street,Suite 1700 San Francisco,California 94104 (415)896-5900 fax 896-0332 email:esa.sf@esassoc.com <br />