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TABLE 1 - CHECKLIST OF REQUIRED DATA FOR NO FURTHER ACTION REQUESTS AT UNDERGROUND TANK SITES
<br /> Site Name and Location: Montgomery Wards/Unocal Station#5098, 5400/5606 Pacific Ave., Stockton, San Joaquin County
<br /> (RB#390215 and 3900014). Both sites were investigated and remediated as one Site after 2000.
<br /> y 1. Distance to production wells for municipal, domestic, A 2001 sensitive receptor survey identified no supply
<br /> a riculture, indust and other uses within 2000 feet of the site. wells located within 2000'of the Site.
<br /> y 2. Site maps, to scale, of area impacted showing locations of From June 1986 through June 1988, two 10,000-gallon
<br /> any former and existing tank systems, excavation contours and gasoline, one 550-gallon waste oil, and two 1,000-gallon
<br /> sample locations, boring and monitoring well elevation and one 500-gallon bulk oil USTs were removed from the
<br /> contours, gradients, and nearby surface waters, buildings, Wards site. In July 1985, two 10,000-gallon gasoline and
<br /> streets, and subsurface utilities, one waste oil USTs were removed from the Unocal site.
<br /> Y 3. Figures depicting lithology(cross section), treatment system Site lithology consists of clay,silt, and sand to 110'bgs,
<br /> diagrams; the total depth investigated.
<br /> Y1 4. Stockpiled soil remaining on-site or o(/-site disposal(quantity); Approximately 200 yds of excavated soil was
<br /> transported offsite by Unocal.
<br /> y 5. Monitoring wells Thirty eight monitoring wells(MW-1 through MW-7, MW-8D,MW-9R, MW-10, MW-10A, MW-11
<br /> remaining on-site, fate; through MW-14, MW-14A, MW-15R,MW-16 through MW-18, MW-18D, MW-195, MW-19D, MW-21S,
<br /> MW-21D, MW-225, MW-22D, MW-235, MW-23D, MW-24S, MW-24D, MW-255, MW-25D, and MW-27
<br /> through MW-31), three vapor wells (SV-1 through SV-3), and forty eight remediation wells (VEW-
<br /> 1A/B through VEW-13A/B, VEW-16, VEW-19, VEW-22, and SP-1A/B, SP-2 through SP-6, SP-7A/B,
<br /> SP-8, AS-14 throw h AS-21, and AS-26) were properly abandoned on 1 February-2011.
<br /> 6. Tabulated results of all groundwater Depth to groundwater varied from 28'to 60'bgs. Groundwater flow
<br /> elevations and depths to water, direction varied from southwest to southeast. Groundwater gradient
<br /> varied from 0.002 to 0.004 ft/ft.
<br /> 7. Tabulated results of all sampling All data adequately tabularized in various reports, including closure report.
<br /> and analyses:
<br /> Y❑ Detection limits for confirmation
<br /> sampling
<br /> �Y 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 shown in applicable
<br /> reports.
<br /> ElLateral and 0 Vertical extent of soil contamination
<br /> Lateral and FiVertical extent of groundwatercontamination
<br /> 9. Zone of influence calculated and assumptions used for subsurface romediation Over-excavation, soil vapor extraction
<br /> system and the zone of capture attained for the soil and groundwater remediation and air sparging were the engineered
<br /> system; remediation.
<br /> 10.Reports/info motion Y Unauthorized Release Form EY QMRs 2/89 to 8/10
<br /> My Well and boring logs Ey PAR FY] FRP ❑y Other Soil Vapor and Risk Assessment(12-10)
<br /> Closure Report 4.11
<br /> Yj 11.Best Available Technology(BAT) used or an explanation for not USTs removal, over-excavation, S VE/AS, and natural
<br /> using BAT; attenuation.
<br /> _yj 12. Reasons why background was/is Minor residual soil and groundwater contamination remains on-site.
<br /> ttainable using BAT,
<br /> y 13.Mass balance calculation of substance The consultant estimates 12,000 lbs of TPHg were present at Wards prior
<br /> treated versus that remaining, to remediation and 11,638 lbs of TPHg were removed by SVE from soil.
<br /> Approximately 356 lbs of TPHg remain in soil and groundwater.
<br /> }, 14. Assumptions, parameters, calculations A 2010 soil vapor survey failed the Region 2 commercial vapor ESLs and
<br /> and model used in risk assessments, and fate CaIEPA CHHSLs; but passed a TIER 2 risk assessment. Residual TPHg
<br /> and transport modeling; and benzene in soil exceeded the ESLs, but is located below 15'b s.
<br /> Z 15. Rationale why conditions remaining at site Soil and groundwater contamination reportedly is limited in extent. Land
<br /> will not adversely impact water quality, health, use(commercial)is not expected to change in the foreseeable future.
<br /> or other beneficial uses; and Vapor intrusion and soil risk has been addressed. Water quality goals will
<br /> be reached in 2038.
<br /> By: JLB Comments: From June 1986 through June 1988, two 10,000-gallon gasoline, one 550-gallon waste oil,and two
<br /> 1,000-gallon and one 500-gallon bulk oil USTs were removed from the Wards site. In July 19857 two 10,000-
<br /> Date: gallon gasoline and one waste oil USTs were removed from the Unocal site. Based upon 71 quarters of
<br /> 4/12/2012 groundwater monitoring showing a stable plume with declining concentrations, no foreseeable changes in
<br /> land use, and limited threats from groundwater,soil and soil vapor intrusion, Regional Board staff
<br /> recommend UST case closure for Wards and Unocal.
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