SITE INFORMATION AND CORRESPONDENCE

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4, TABLE 1 - CHECKLIST OF REQUIRED DATA � FOR NO FURTHER ACTION REQUESTS AT UNDERGROUND D TA NK SITES � 13336 E. H 88, Lockeford, San Joaquin County Site Name and Location: Former Town 8�Country Chevron, Hwy. q h► L Mokelumne River 1 mi North and West Na 1:Distance to production wells for municipal, domestic, agriculture, industry and Bear Creek 3/4 mi southeast i other uses within 2000 feet of the site; 2. Site maps to scale of area impacted showinglocations of farmer and existing tank systems need subsurface u00-7,s excavation contours and sami2le location , boring and monitoring well elevation contours, 10,000 gal reg., 5,000-7,000- gradients, and nearby surface wafers, buildings, streets: and subsurface utilities; gallon unleaded, 550-gallon waste oil removed 1991 EYD 3. Figures depicting lithology(cross section), treatment system diagrams; on-site geologic logs contain limited into. Regional geologic logs complete t 'k a 4. Stockpiled soil remaining on-site or off-site disposal(quantity); Unknown'amount disposed off-site 6 barrels of soil(drill cuttings)disposed at Forward 6 borings_destroyed --5.'Monitoring wells remaining.on=site;•fate;..` Borings 0 to 30 ft bgs ground water not encountered 6. Tabulated results of a!!groundwater elevations and depths to water, SJ Closure Summary 70-100 ft bgs E, 7.Tabulated results of all sampling and analyses: MTBE Defection limits 0.105 to 36 mg/kg needs to be 0.05 mg/kg Other oxygenated detection limits 0.4 to 8 mg/kg Y�Defection limits for confirmation sampling FLead analyses NA 8. Co ion contours of contaminants found and those remaining(ri s i TPH-g and BTEX extend laterally beyond and groundwater, and both on-site and off-site: 8-3,4,and 5, beneath Maintenance Shop N Lateral and N Vertical extent of soil contamination and extend vertically beyond 26 ft bgs in B-1 and 21 ft in B-5 Vertical extent of L'J Latera!andN Vertical extent of groundwater contamination initial release not defined NA 9.Zone of influence calculated and assumptions used for subsurface remediation system and the zone of capture attained for the soil and groundwater remediation system; 0 10.Reports/information Fl Unauthorized Release Form 2/17/88 8 8/27/91 ❑N QMRs(Dates) Welland boring logs Other(report name) Subsurface Environmental Investigation 918197& 11/9/97 ABest Available Technology(BA 7) used&-6" i explanation for hot using BAT, `�contarriinatecJ "soil remainsladdiiionai'��"—=' remediation may be required 1FN 12.Reasons why background was Contamination beneath bldg, and portion not beneaths unattainable using BAT; bldg. extends to greater than 26 ft bgs. 0 13.Mass balance calculation of substance treated versus that remaining; Vertical extent of contamination unknown 14.Assumptions, parameters, calculations and model used in risk RBCA needs to be conducted to determine the effect of assessments, and fate and transport modeling; benzene on indoor air quality 015' .Rationale why conditions remaining at site will not adversely Vertical extend of contamination is greater than 26 ft impact water quality, health, or other beneficial uses,and bgs. Wafer table 70-100 ft bgs. Contamination could extend to'�water table. KI 16.WET or TCLP results Need to determine the concentration of contaminated water migrating through the vadose zone to potentially impact gw By. Comments: Board staff do not concur with San Joaquin County. Further investigation is needed at this site to determine the vertical extent of soil contamination due to the initial release of petroleum contaminants. Da The initial contamination may have impacted ground water. I4