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1 LCA <br /> ENVIRONMENTAL 2Q C�RYat�xE P1A7 • PCJRT BEACH;CAUF©R:vL1 9266{ <br /> H <br /> J CONSULTANTS ,,� ENVIRONMENTAL HEA1 DIVISION <br /> Jbi TEL:(949)6f4 0 Ftiz:(949)64x•2691 <br /> R 0. Box 388, Stockton CA 85201-0388 - <br />} Approved <br /> j }`n <br /> Denied <br /> Conditions ' t f c: , 1 fc w e f/S prr c z <br /> ray .) � / <br /> Date f 7 byl \ <br /> October 19 1 \ �xaf`°:fh°51t&e) q <br /> 99 <br /> Public Health Services\fi�an Jvagvi i County <br /> Attn: Ms Carol Oz � <br /> 304 East Weber Avenue, Thir ear <br /> Stockton, California '.5201 �` <br /> Subject. (Revised)Wdck Plan for Groundwa#er Assessmen#Nand Manitoring 1e[1 Irtstallatiort , <br /> at Joe's Truck Stop, at 15600 South Harlan Road, Lathrop, California. <br /> M.54 Viz: i <br /> Pursuant to your:request, Avalon.Environmental Consultants (Avalon,) is Teased to submit this. <br /> work plan to perform a Groundwater assessment and Monitoring W611 Installation at Joe's <br /> Truck Strep at `1.5600 South Harlan Road in Lathrop, County of San Oaquin, California. This <br /> investigation will ist of installing six groundwater monitoring wells on the subject <br /> property. The purpose of this investigation is to establish the groundwater gradient, and to <br /> monitor levels of Methyl Tertiary Butyl Ether (MTBE) and other hydrocarbon contamination <br /> in the groundwater. The impact W45previously identified through groundwater grab samples <br /> collected by Avalon, during a Phase 11 Site Assessment dated december 17; 198. Elevated <br /> levels of diesel at Ill . .0 parts per billion (ppb) and 5;200 ppb were identified in the ' <br /> groundwater samples from two. borings In the area of the former diesel tank it in the southern <br /> I <br /> portion of the property. Elevated levels.•of 1vt`TBE, were identified in ;groundwater samples- <br /> taken from borings io the northern'tarik pit area. Levels imthe groundwater were as high as <br /> 1.,700 ppb. Due to these elevated levels of hydrocarbons, adder"{nal"characterization was <br /> recomrrrended by the' <br /> consultants. <br /> This investigation wi:ll consist of drilling and sampling s'rx groUndvivater monitoring wells on <br /> the subject property. The levels of contamination identified in Avalon's Phase ll report <br /> suggests.that.the gradient is to the north, however,:a true gradient +direction:on: the subject <br /> property has not been established. Wi .recommend placing g one monitoring well in the center <br /> of each of the tank areas (Cine in the northern tank area and one in the southern tank area). <br /> Additionally, one monitoring well is recommended north of the northern tank area and three <br /> monitoring wells are recommended in the remaining three corners of the property. Once <br /> monitoring well construction is complete,.and the monitoring wells have been developed,the <br /> locations and top of:casings will be surveyed by a State Licensed Laird Surveyor. Once this <br /> is complete, the well's will be given one week to stabilize, prior to measuring and sampling. <br /> This will allow groundwater levels:to stabilize, thereby giving;accurate data. <br /> :i <br /> I <br /> F <br />