SITE INFORMATION AND CORRESPONDENCE_CASE 2

Home Browse Search

I ti � TABL - CHECKLIST OF REQUIRED D E f FOR NO FURTHER ACTION REQUESTS AT UNDERGROUND TANK SITES Site Name and Location; Conti Trucking, 2660 Loomis Road, Stockton, San Joaquin County 1. Distance to production wells for municipal, domestic, agriculture, A receptor survey was not co eted. The nearest industry and other•uses within 2000 feet of the site; well is an onsite domestic 11 approximately 150 feet R northeast of the former U s. 2. Site maps, to scale, of area impacted showing locations of former and existing tank system , Two diesel USTs removed in excavation contours and sample locations, boring and monitoring well elevation contours, September 1999. Site maps gradients, and nearby surface waters, buildings, streets, and subsurface utilities; provided. Y� 3. Figures depicting lithology(cross section), treatment system diagrams; Boring l gs show predominantly sand and silt. 4. Stockpiled soil Temaining on-site or off-site disposal(quantity); Approxi telt'750 cubic yards of stockpiled soil remain on-site. Soil will be backfilled following Count approval. 0 5. Monitoring wells remaining on-site, fate; Monitoring wells were no installed. _.. _�6.,Tabulated..results of_allgroundwater_ele.vations,and_depths,_to_wate Depth to water is estimated at 60 feet with an easterly flow Groundivafer was not encountered.-`-' 71 7.ID Tabulated results of all sampling and analyses: Maximum s !results in mg/kg show TPHd at 13,000,and toluene at 0.005 at th tank pit. Results of three soil borings in mg/kg show non Detection limits for confirmation sampling detect for all constituents except toluene at 0.070,and xylenes at N� Lead analyses 0.026. tBE was reported at<0.05 mg/kg by 8020. y� 8. Concentration contours of contaminants found and thos remaining in soil Lateral and vertical extent of contamination and groundwater,Mand both on-site and off-site: is defined. Latera!and Vertical extent of soil co tamination Lateral and Vertical extent of grou water contamination i 9.Zone of influence calculated and assumptions u ed for subsurface A remediation system was not operated at remediation system and the zone of capture attai ed for the soil and this site. groundwater reme,"diation system; Y❑ 10.Reports/information Y❑ Unauthorized Blease Form FN 1 QMRs Boring logsPAR 0 FRP Other(PIER, March 2000) 11.Best Available Technology(BAT)us or an explanation for not using BAT,• Remove USTs,natural atten tion. 12.Reasons why background was/is �\ .unattainable using IBAT• 1TPHd and BTEX constituents remain in on-site sails. k' 13.Mass balance calculation of s bstance treated versus that'rerriaining; ' A mass balance was not presented, n �, 0 14.Assumptions,parameters calculations and model used in risk k assessments, and fate and nsport modeling, A risk assessment was not completed. is I 15. Rationale why pondi ons remaining at site will not adversely Remaining contamination is limited to the tank pit area. 0 impact•water quality, he lth, or other beneficial uses;and Contamination will naturally attenuate. By: Comments Two diesel USTs were removed from the site in September 1999. Tank pit samples show soil contamination.- Three geoprobe borings were completed to 30 feet bgs in February 2000, and only low concentrations of toluene and xylenes were identified in soils. MtBE analyzed by 8020 was not identified at this site. An on-site water f supply well isaocated northeast of the former USTs, and sample results were not provided for this well. Although Date: groundwater is estimated at 60 feet, if is in the best interest of Conti Trucking to sample their well for petroleum hydrocarbons. Based on the limited extent of site contamination,and the absence of fuel oxygenates, Board staff concurs with San Joaquin County's closure recommendation. I 1,