SITE INFORMATION AND CORRESPONDENCE

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r TABLE 1 - CHECKLIST OE REQUIRED Dr%rA FOR NO FURTHER ACTION REQUESTS AT UNDERGROUND TANK SITES Site Name and Location: Independent Trucking,401 South Lincoln street,Stockton,San Joaquin County A well receptor survey identified three water supply Y 1. Distance to production wells for municipal, domestic,agriculture, ells within 2,000 feet of the site. The nearest well is industry and other uses within 2000 feet of the site; approximately 1,440 feet southeast of the site. site maps are provided in 2. Site maps, to scale, of area impacted showing locations of former an existing tank systems, tine various reports. Two excavation contours and sample locations, boring and monitoring well elevation contours, USTs were removed from gradients, and nearby surface waters, buildings,streets, and subsurfac utilities; the site. cross section treatment system diagra s; Boring logs show silty clay and silty sand to 3.Figures depicting lithology( ). 30 feet, the total depth completed. The disposition f excavated soil during UST removal was not 4. Stockpiled soil disposed off-site(quantify); presented. it was likely returned to the tank pit excavation. 5. Monitoring wells remaining on-site, fate; Three monitoring wells remain on-site. The wells will be properly destroyed pending site closure. Groundwater levels varied from 12 to 15 feet below a6. Tabulated results of all groundwater elevations and depths to water, Around surface, and flow is to the northeast 7.Tabulated results of a!1 sampling and analyses: Samples collected in January 2001 show TPHd at 210 pg/l In only one Y of the three on-site monitoring wells. All other constituents including, Q 0 Detection limits for confirmation sampling MtBE,and other fuel oxygenates are non-detect at acceptable Lead analyses detection limits. Groundwater samples analyzed in October 2001, © reported lead at<5pg/l. The highest concentrations of soil Y 8. Concentration contours of contaminants found and those remaining in soil contamination were identified at 25 to 30 and groundwater, and both on-site and off-site: feet in one boring. The depth to © Lateral and Yn Vertical extent of sol/contamination groundwater varied from 12 to.15 feet Lateral and ❑ Vertical extent of groundwater contamination below ground surface. 19 Based on the limited contamination, site 9.Zone of influence calculated and assumptions used for subsurface remediation beyond UST removal was not Qremediation system and the zone of capture attained for the soil and required. groundwater remediation system; 10.Reports/information y❑ Unauthorized Release Form 19 QAIRs(12199, 6/00, 10/00, 1/01,and 10/01) 0 Boring logsPAR FRP ther(No Further Action Request) F1 El8A used or explanation for not using BAT,. Remove the USTs to eliminate the source of Y� 11.Best Available Technology(BAT) p contamination. TPHd contamination r mains in groundwater in one monitoring well. The Y� 12.Reasons why background wasfis remaining contamination does not present a significant threat to water quality. unattainable using BAT, t1 Based on the limited groundwater contamination, the remaining mass of 13.Mass balance calculation of substance contamination in soil nd groundwater was not required. treated versus that remaining; ased on the limited groundwater contamination,a risk 14.Assumptions,parameters, calculations and model used in risk ssessment was not required. assessments, and fate and transport modeling; ted in extent,and 15. Rationale why conditionsor her beneficial uses;and oncentrations ning contamination decreasing.lContamination will FTlimpact water quality,health, aturall degrade, By: Comments:Independent Trucking and Delta Paper formerly ccupied the site. One 550-gallon gasoline UST was MH removed in September 1999, and another UST of unknown uantity and volume was removed prior to 1984. Soil and in Sept mber 1999 showed contamination, and multiple borings and groundwater samples collected during UST removal three monitoring wells were installed in December 1999. Th wells were monitored from December 1999 to Date: January 2001 to 210 my during the four quarters of mon tori g.PHd was confirmedin one of the BMtBEmonitoring wa�dentiified at aentrations of TPHd decreased maximum off 1.4 pg/1 n one well 1/31102 from 8i0 Ng/! Ng/l in December 1999,but it was not confirmed in the following ampling events. The remaining contamination n groundwater is limited in extent, and will naturally degrade. Based on the site investigation and activities completed to date, Board staff concur with San Joaquin County's closure ecommndation.