SITE INFORMATION AND CORRESPONDENCE

Home Browse Search

N-/FABLE 1 -CHECKLIST OF REQUIRED DAT) / FOR NO FURTHER ACTION REQUESTS AT UNDERGROUND TANK SITES Site Name and Location: City of Tracy/Delta Disposal, 99 West Sixth Street, Tracy,San Joaquin County(RB#390510) Y 1. Distance to production wells for municipal, domestic, A 2003 sensitive receptor survey reported one water agriculture, industry and other uses within 2000 feet of the supply well(1000'southeast), one domestic well(1900' site. south),and one irrigation well(1200'west)within 2,000'of the Site. The wells are not threatened by this release. Y 2. Site maps, to scale, of area impacted showing locations of any former In 1985(exact date unknown), one 550-gallon and existing tank systems, excavation contours and sample locations, gasoline and one 350-gallon diesel USTs were boring and monitoring well elevation contours, gradients, and nearby removed. surface waters, buildings, streets, and subsurface utilities; Y 3. Figures depicting lithology(cross section), treatment system diagrams; Site lithology consists of clay,silt,and sand to 26.5, the total depth investigated. N 14. Stockpiled soil remaining on-site or off-site disposal The fate of excavated soil was not discussed in the available (quantity); reports. Y] 5. Monitoring wells remaining on-site, fate; Three(3)monitoring wells(MW-1 through MW-3)will be properly destroyed. 6. Tabulated results of all groundwater Depth to groundwater varied from 15'bgs to 17'bgs. Groundwater flow direction elevations and depths to water, I varied from north to northwest. Groundwater gradient was not calculated. 7. Tabulated results of all sampling All data adequately tabularized in various reports,including closure report. and analyses: ElDetection limits for confirmation sampling EN Lead analyses 8. Concentration contours of contaminants found and those remaining in The extent of the identified contamination is soil and groundwater, and both on-site and off-site: described in the available reports. 0 Lateral and LU Vertical extent of soil contamination Lateral and nY Vertical extent of groundwater contamination 9. Zone of influence calculated and assumptions used for subsurface An engineered remediation was not required remediation system and the zone of capture attained for the soil and by the regulatory agency. groundwater remediation system; 10.Reports/information QY Unauthorized Release Form QY QMRs(3) 12-08 to 8-09 FY] Well and boring logs �Y PAR FRP ❑Y Other Closure Report(9-10), Closure Report Addendum 11-10 Y J 11.Best Available Technology(BAT) used or an explanation USTs removal and natural attenuation. for not using BAT; Y 12. Reasons why background wasps unattainable Residual soil contamination remains under Sixth Street. gr BAT, Y 13.Mass balance calculation of substance treated Consultant estimated approximately 167 gal. of TPH remains in soil and 0.0004 gal. of TPH remains in groundwater. versus that balance remaining; Y 14. Assumptions,parameters, calculations and Soil vapor was-not-tested.-Soil failed Region 2 ESLs for TPHg and 7 model used in risk assessments, and fate and TPHd at 16.5'bgs. Tanks were under Sixth St. Consultant states transport modeling; site does not represent a significant risk. Y115. Rationale why conditions remaining at site will Soil contamination reportedly is limited in extent. Groundwater not adversely impact water quality, health, or other plume has reached non-detect. Land use(public street)is not beneficial uses;and expected to change in the foreseeable future. TPH has reached WQGs. By: JLB Comments:In 1985(exact date unknown), one 550-gallon gasoline and one 350-gallon diesel USTs were removed at the subject site(Sixth Street).Residual soil contamination remains under Sixth Street. Based Date: upon the limited extent of contamination reported in soil,groundwater reaching WQGs,no foreseeable 9/11/2012 changes in future land use(public street), and minimal risks from soil vapor and soil,Regional Board staff concur with San Joaquin County's Closure Recommendation.