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I ABLE 1 -CHECKLIST OF REQUIRED DATA O
<br /> i FOR NO FURTHER ACTION REQUESTS AT UNDERGROUND TANK SITES 7`Grf.l4�
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<br /> rSiteNamend Location: Ed's MuNler—Cox 8 Cox Bros., 595 E. 11v St., Tracy, San'Joaquin County(RB 11390479)
<br /> nce to production wells)for municipal, domestic, A sensitive receptor survey In 1999 identified one
<br /> lture, industry and other uses within 2000 feet of the site. municipal supply well(1,000'southwest)and one
<br /> 4 domestic well 1,900'south within 2,000'of the Site.
<br /> Y 2. Site maps, to scale, of area impacted showing locations of Two 4,000-gallon regular gasoline, one 7,500 gallon and
<br /> any former and existing tank systems, excavation contours and one 8;000-gallon unleaded gasoline,and one 1,000-gallon
<br /> sample locations, boring and monitoring well elevation - waste oil USTs and associated piping were removed 1/90.
<br /> contours, gradients, and nearby surface waters, buildings,
<br /> streets, and subsurface utilities;
<br /> Y1 3. Figures depicting litho/o '' ) y Site litholo consists of clay,9 P 9 gy(cross section), stem 9Y y,silt, and sand to 30; the
<br /> diagrams; total depth investigated. `
<br /> Y1 4. Stockpiled soil remaining on-site or off-site disposal(quantity); In 3/04, 900 cubic yards of soil was over-excavated and
<br /> dis osed at Forward Landfill in Manteca.
<br /> Y 5. Monitoring wells remaining on-site, fate; Nine monitoring wells(MW-1, MW-2, MW-3R, and MW-4 through MW-8 and
<br /> , MW-9R, installed 1994 and 2004, will be ro erl abandoned.
<br /> YJ 6. Tabulated results of all groundwater Depth to groundwater varied from 7'to 9'bgs. Groundwater flow
<br /> elevations and de ths'to water ii direction was towards the north,gradient varied from 0.002.to 0.003 ft/ft.
<br /> =`• 7. Taoulated-results-of'alhsam lm - -In.119O-the US-Ts-removal-confirmation-maximum-soil-concentrations-were TPHd,---. - �
<br /> and analyses: j 29,800 mg/kg;toluene, 1097 mg/kg;ethylbenzene,323 mg/kg;and xylenes,
<br /> '! 2,602 mg/kg;and from soil borings advanced in 2001, TPHg, 8,300 mg/kg and
<br /> Y❑ Detection limits for confirmation benzene, 37 mg/kg. In 3/04, maximum soil confirmation results(sidewalls)were
<br /> sampling TPHg, 10,000 mg/kg;benzene, 5.9 mg/kg;toluene, 200 mg/kg;ethylbenzene,
<br /> 160 mg/kg;and xylenes, 900 mg/kg. In 1996, maximum grab groundwater results
<br /> FYI Lead analyses were TPHg, 1,900 ug/L;toluene, 7.4 ug/L;ethylbenzene, 64 ug/L;and xylenes,
<br /> 74 ug/L;and 10/01,maximum groundwater monitoring result for benzene was
<br /> 3.1 ug/L. In 10/08,maximum groundwater monitoring results were TPHg, 130 ug/L;
<br /> and TPHd, 130 u L. MTBE and 1,2-DCA were not detected in soil or groundwater.
<br /> 8. Concentration.contours of contaminants found and those remaining in soil and The extent of the identified
<br /> groundwater, and both on-site and off-site: contamination is described in the
<br /> ❑Latera/and
<br /> Y M'! extent of soil contamination reports. F
<br /> Lateral and Vertical extent of groundwater contamination
<br /> 9. Zone of influence calculated and assumptions used for subsurface remediation Over-excavation of soil with open pit
<br /> system and the zone of capture;attained for the soil and groundwater remediation groundwater pumping, treatment and
<br /> system; " disposal into City sewer,as required by
<br /> I the lead agency.
<br /> 10.Reports/in/ornation �Y Unauthorized Release Form FYIOMRS 48 from 9/94 to 10/08
<br /> FY Well and bwirg logs PAR FY FRP FY Other Add. SI(7/96); Soil Gas Rpt. (6/07);NFAR(7/99;3/08) l
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<br /> YJ 11.Best Available I Technology(BAT) used or an explanation for not using USTs removal,soil over-excavation with
<br /> BAT,' batch open pit groundwater
<br /> _ __removal/treatment,-and-natural attenuation..._
<br /> Y 12. Reasons why'background wasrs unattainable Minor residual soil and groundwater contamination remain on-site.
<br /> BA T'.
<br /> Y 13.Mass balance calculation of substance treated In 10/04, calculated mass removed was TPHg, 788 gal.and benzene,
<br /> versus that remaining; 4.2 gal. (soil);and TPHg, 2.3 gal. and benzene, 0.21 gal. (groundwater).
<br /> In 3/08, estimated remaining mass was TPHg, 32 gal.and benzene,
<br /> - 0.03 gal. (soil); with TPHg, 13 gal.and benzene 0.01 gal. (groundwater)
<br /> �, 14. Assumptions,,parameters, calculations and 2007 soil gas sample results show residential Region 2 ESLs were not
<br /> model used in risk assessments, and fate and exceeded. The site is a business in a mixed residential/commercial
<br /> transport modeling; I1 1 area of Tracy.
<br /> Y 15. Rationale why conditions rdmaining at site will Soil and groundwater contamination reportedly is limited in extent
<br /> not adversely impact water quality, health, or other Land use(residential/commercial)is not expected to change in the
<br /> beneficial uses;and II foreseeable future.
<br /> By: JLB Comments: Two 4,000-gallon regular gasoline, one 7,500 gallon and one 8,000-gallon unleaded gasoline,and
<br /> one 1,,000-gallon waste oil USTs and associated piping were removed 1/90 from the subject site. Over-
<br /> Date: excavation of soillto the maximum practical extent and batch removal of over 239,000 gallons of pit water in
<br /> 5/11//2009 2004 have significantly reduced contamination leaching to groundwater. Based upon 48 quarters of
<br /> groundwater monitoring showing a stable plume with declining concentrations, the limited extent of
<br /> contamination remaining in soil and groundwater, no foreseeable changes in land use, and no applicable
<br /> ESLs exceeded, Regional Board staff concur with San Joaquin County's Closure Recommendation. kk
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