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M. I STE ASSESSNEENT IMK PUSN Shell Station 420 U. Kettleman Lane Lodi, California Aegis Projeet No. 99.013 page 5 2.2 Previous Work In October, 1989 Aegis submitted a "PreTank Replacement Site Assessment Results Report." The findings are as follows: 2.2.1 Soil Conditions A total of fifteen soil borings were drilled, sampled and logged, according to approved methods. Five soil borings were in t;b vicinity of the existing tank basin and associated plumbing system, eight were located in the proposed tank field, and two at the western fuel island as identified in figure 3. In summary, soil types are relatively consistent across the site, silt (Unified Soil Classification System symbol ML) was the predominant soil type encountered with sand lenses occurring sporatically throughout the soil borings. Gasoline odor observations, PID readings, and •.soil sample analytical laboratory results-do not indicate marked impact to the subsurface adjacent to the existing + ,k 1--s2n and prrduct. lines. The presence of hydrocarbons .; ,s noted in the northwestern boring (B-8) adjacent. to the storm drain closest to the intersection. The source of ' petroleumhydrocarbons in a soil at a concentration of 1,060ppm ! of Total .Petroleum Hydrocarbons as Gasoline in such a confined, i area may have .resulted from the exisitng vapor linea and/or a �i -,thef,..::port associated.with Shell's underground.storage system. For detailed.information please refer to section 3.O of Aegis "PreTank Replacement .Site Assessment Results Report" (Aegis, ! { October, 1989) : - f: ! 2.2.2 Groundwater Conditiljns f Data collected from Monitoring Wells installed within a 1/2 mile radius of the siteindicates that groundwater is at approximately j 50 feet below grade. j 3.0-WORK PT.IAN I A total of three soil borings will be advanced according to San Joaquin County and:Tri--Regional guidelines at the approximate ' locations shown.on figure 4. Final borehole placement will be i subsequent to location ofsubsurface utilities ,by USA alert and facility employees. The soil.borings are located to further -..__ -- -- r.- ---,---evaluate-potential-undergraund-'storac}e-.tanlr"and .associated piping -- releases, and converswion. to monitoring wells will assist in : establishing the direction :of groundwater .flow and hydraulic gradient on-site. Actual depth of the wells/soil borings will be E J dependant upon depth to .ground water. The three soil borings will be converted to monitoring wells according to methods in - - -- 112