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a Project No. S8080-06-02 '� s September 30, 1994 Page } a the site by Texaco in 1979. Although excavated soil was reportedly aerated for-several;months after the tanks:were removed, no soil sampling or analytical test results were deported.. aI Petroleum hydrocarbon soil_impacts at the site were initially reported by Uriah Incorporated in. April 1991, at depths between 15 and 20'feet below the existing ground surface(bgs)in boring SB=-. located near the f. rted location of the former Texaco USTs Uriah subsequently performed eight additional borings (SB-4 through SB-11) and converted thkee of the borings into groundwater monitoring wells_WW-1,1vT'UV-2 and MW-3)at the locations depicted vn Figure 2. Uriah reported i the presence of residual totalpetroleum hydrocarbons as gasoline(TPHg) and diesel(TPHdjin sosl. between the depths of approximately 15 and 35'feet.bgs and detected the presence ofTPHg,methyl. tert-butly ether>(1V IME, .a.;gasofine additive) and halogenated volatile organic.cotripounds in the groundwater at a depth of approximately 55 feet:bgs. Uriah and.EP 1 f Technologies installed one vapor extraction well in,the vicinity of`boring EB-11 which had the.. highest detected TPHg and TPHd concentrations of 11,000 and 2,400 mg/fig; respectively.: Boring EB41 and the vapor extraction well are;located near the,reported location of the former Texaco USTs as depicted do Figure 2. A vapor extraction system`was optrated at the .site between June 1993 and March 1994 and reportedly removed.approximately 3,333 pounds of . - gasoline.. ;: a Ceocon measured the relative groundwater elevations in the Qnsitemonitoring wells.MW-1, MW12 and MW-3 on July 1 and 27, 1994: Groundwater was generally encountered between the depths of 55and 57 feet bgs with a calculated hydraulic gradient of 6;002 directed to the southwest. The monitoring wells were sampled on July 1, 1994. TPHg as gasoline was detected at a doOd ntraddi of 64 ug/L in MW-3. MISE and P( >U were reported in each well at concentrations:between 2.1 and 150 ug/L, and. 1.9 and.12 ug/L, respectively. Geocon excavated five continuous-core exploratory borings(G8-1 through,:O 5)within the parking lot area of the site on July 13 and 14, 1:.994. Soil samples obtained from.borings t'..,B-1, GB-3 and GB-S indicated the presence fTPlg at maximum reported concentrations between 1,600 and 3,100 mg/Kg between depths of approximately 27.5 and 42.5 feet bgs. TPHd. concentrations were reported between 3.4 and 250 mg/Kg in borings GB-1 and GA-3 at depths between 18 and 32=5 feet bgs. Nondetected concentrations of the target compounds were reported for soil samples obtained from borings GB-2 and GB4 A summary of the historical soil and groundwater analytical results are presented on the attached Tables I, II and IV. A summary of the historical reported groundwater elevation data is presented on the attached Fable III. The TPHg soil impacts appear to be bounded on the northwest,west and southern site boundaries by borings GB4, EB-7, EB-4 and EB-6 as depicted on Figure 2. The vertical distribution of the soil impacts encountered generally extend between depths of 15 to 45 feet bgs. �l PURPOSE The purpose of the scope of:services presented herein is to further delineate the lateral and vertical extent of residual TPH in soil.and groundwater at the site and within.the adjacent ptbltc streets to a x i j