SITE INFORMATION AND CORRESPONDENCE_3

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TABLE 1 -CHECKLIST OF REQUIRED DATA FOR NO FURTHER ACTION REQUESTS AT UNDERGROUND TANK SITES Site Name and Location: Del Monte 33/Dlsco UST 110 N.Filbert St., Stockton San Joaquin County(RB#390812) :Yj 1. Distance to production wells for municipal,domestic, A 2009 sensitive receptor survey stated no wells are agriculture,industry and other uses within 2000 feet of the site. located within 2,000'of the Site. 2. Site maps, to scale, of area impacted showing locations of In October 1985,three 10,000-gallon gasoline USTs were any former and existing tank systems, excavation contours and removed from the former Disco service station. sample locations, boring and monitoring well elevation contours, gradients, and nearby surface waters, buildings, streets and subsurface utilities; Y 13. Figures depicting lithology(cross section), treatment system Site lithology consists of clay,slit,sand,and gravel to diagrams; 185', the total depth investigated. Y1 4. Stockpiled soil remaining on-site or off-site disposal(quantity); The excavated soil was aerated onsite down to TPH concentration of 1,000 mg/kg and placed back Into the tank pit yj 5. Monitorin wells remainingon-site, fate; FNry three wells in 48 borings(5 nested)will be properly abandoned. 8. Tabulated results of all groundwater Depth to groundwater varied from 39'to 58'bgs. Groundwater/low elevations and depths to water, direction varied from north to east to south. Groundwater gradient was not calculated -- - - - - — 7. Tabulated results of all sampling All date adequately tabulartzed In various reports,Including closure report. and analyses: FYI Detection limits for confirmation sampling ❑Y Lead analyses 8. Concentration contours of contaminants found and those remaining in soil and The extent of the identified groundwater, and both on-site and off-site: contamination Is shown In applicable reports. it Lateral and Y❑Vertical extent of soil contamination FYI Lateral and M Vertical extent of groundwatercontamination 9. Zone of influence calculated and assumptions used for subsurface remediation Over-excavation,soil aeration and vapor system and the zone of capture attained for the soil and groundwater remediation extraction,and air and ozone sparging system" were the engineered remediation. 10.Reports/information Y Unauthorized Release Form [0QMRs 57 from 7191 to 3/09 ❑Y Well and boring logs QY PAR FRP Other Closure Report(10(09) Yj 11.Best Available Technology(BAT)used or an explanation for not USTs removal, SVE/AS,and natural attenuation. us! 8AT 12. Reasons why background wasfis Minor residual soil and groundwater contamination remain on-site. Y itainable using SAT - 1-3 Mass rox/mate/y 9,810 pounds o1 TPH were rwnowal by SVE and ozone sparg ng. The eonsulte�stim Upounds of7Pfrramwln-ft4w versus that remaining; and groundwater. Y 14. Assumptions,parameters, calculations and The consultant stated results of soil vapor samples did not exceed model used in risk assessments, and fate and ESLs,and do not pose a risk from vapor Intrusion.After soil samples transport modeling," did not exceed ESLs. 15. Rationale why conditions remaining at site Sol/end groundwater contamination reportedly are limited In extent. will not adversely impact water quality, health, or Land use(commercial)Is not expected to change In the foreseeable other beneficial uses;and I future. WQGs will be reached In 17.7 years. By.- JLB Comments:In October 1985,three 10,000-gallon gasoline USTs were removed from the former Disco service station..Based upon 57 quarter of groundwater monitoring showing a stable plume with declining Date: concentrations, the limited extent of contamination remaining In soil and groundwater,no foreseeable 4/1/2010 changes in land use,and minimal threats from soil vapor Intrusion,Regional Board staff concur with San Jos uln Coun s Closure Recommendation.