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',,ABLE 1 -CHECKLIST OF REQUIRED DATA_-
<br /> FOR
<br /> FOR NO FURTHER ACTION REQUESTS AT UNDERGROUND TANK SITES
<br /> Site Name and Location: ARCO Station#4493, 205 Center St., Stockton, San Joaquin County(RB#390586)
<br /> Y 1. Distance to production wells for municipal, domestic, A 2004 sensitive receptor survey stated eight municipal
<br /> agriculture, industry and other uses within 2000 feet of the site. +wells are located within 2,000 of the Site. The nearest
<br /> well is 1,000'southeast of the site.
<br /> Y 2. Site maps, to scale, of area impacted showing locations of In February 1999, three 12,000-gallon gasoline and one
<br /> any former and existing tank systems, excavation contours and 300-gallon waste oil USTs were removed.
<br /> sample locations, boring and monitoring well elevation
<br /> contours, gradients, and nearby surface waters, buildings,
<br /> streets, and subsurface utilities;
<br /> Y1 3. Figures depicting lithology(cross section), treatment system Site lithology consists of clay, silt,and sand to 80, the
<br /> diagrams; total depth investigated.
<br /> Y 4. Stockpiled soil remaining on-site or off-site disposal(quantity); Approximately 367 tons of excavated soil was
<br /> transported to BFl/VASCO in Livermore, TPS TECH in
<br /> Richmond,and CHEM WASTE in Kettleman Hills.
<br /> 5. Monitoring ing wells remaining on-site, fate; Nineteen monitoring wells(MW-1 through MW-7, MW-8M through MW-13M,
<br /> and MW-8D through MW-130)will be properly abandoned.
<br /> Depth to groundwater varied from 11'to 27'bgs. Groundwater flow
<br /> 6. Tabulated results of all groundwater
<br /> �- -elevations and-depths-to-water, directionwas primarily towards the northeast. Groundwater gradient
<br /> _
<br /> 7. Tabulated results of all sampling All data adequately tabu larized in various reports,including closure report.
<br /> and analyses:
<br /> FY Detection limits for confirmation
<br /> sampling
<br /> Lead analyses
<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 shown in applicable .
<br /> reports.
<br /> Lateral and Y❑Vertical extent of soil contamination
<br /> NJ Lateral and FY Vertical extent of groundwater contamination
<br /> 9. ,Zone of influence calculated and assumptions used for subsurface remediation Over-excavation of soil was the
<br /> system and the zone of capture attained for the soil and groundwater remediation approved remediation.
<br /> system;
<br /> YJ 10.Reports/information 0 Unauthorized Release Form 0 QMRs 38 from 12/99 to 1110
<br /> CY Well and boring logs ❑y PAR R FRP RY Other Closure Report(8106)and Revised Closure Report
<br /> 10/06
<br /> Y 11.Best Available Technology(BAT) used or an explanation for not UST removal, aver-excavation, and natural
<br /> using BAT; attenuation.
<br /> Y 12. Reasons why background wads Minor residual soil and groundwater contamination remain on-site.
<br /> _- ttainable-using-BA-T;.
<br /> Wy 13.Mass balance calculation of substance treated The consultant estimates 35 lbs..of TPH remain in soil and 11 lbs, of
<br /> TPN remains in groundwater.
<br /> versus that remaining;
<br /> Y 14. Assumptions, parameters, calculations and The site and adjacent property where soil and groundwater
<br /> 7
<br /> model used in risk assessments, and fate and contamination remain are both open land in a City of Stockton
<br /> transport modeling; waterfront park, will not be redeveloped with buildings;and as such,
<br /> residual soil and groundwater does not pose a risk from vapor
<br /> intrusion.All soil contamination encountered during redevelopment
<br /> was property addressed with CA-DTSC and County oversight.
<br /> Y 15: Rationale why conditions remaining at site Soil and groundwater contamination reportedly are limited in extent
<br /> will not adversely impact water quality, health, or Land use(City waterfront park entrance)is not expected to change in
<br /> other beneficial uses;and the foreseeable future. WQGs will be reached in 10-30 years.
<br /> By: JLB Comments:In February 1999, three 12,000-gallon gasoline and one 300-gallon waste oil USTs were removed.
<br /> from the subject site. Based upon 38 quarters of groundwater monitoring showing a stable plume with
<br /> Date: declining concentrations, the limited extent of contamination remaining in soil and groundwater, no
<br /> 6/2412 0 1 0 foreseeable changes in land use,and minimal threats from soil vapor intrusion, direct contact, and gross
<br /> contamination Regional Board staff concur with San Joaquin County's Closure Recommendation.
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