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<br /> E TABLY1 - CHECKLIST OF REQUIRED DVA
<br /> FOR NO FURTHER ACTION REQUESTS AT UNDERGROUND TANK SITES
<br /> E
<br /> ite Name and Location: Ruiz Grocery,4491 West Durham Ferry Road, Tracy, San Joaquin County
<br /> 0 1. Distance to production wells for municipal, domestic, agrloulfa e, Twelve water supply wells identified within 2,000 feet
<br /> industry and other uses within 2000 feet of the site; of the former USTs. The nearest well ls.on-site
<br /> approximately 80 feet north of the former USTs.
<br /> 0 2. Site maps, to scale, of area impacted showing locations of former and existing tank systems, Two USTs were removed in
<br /> excavation contours and sample locations, boring and monitoring well elevation contours, 1989. Site maps provided.
<br /> gradients, and nearby surface waters, buildings, streets, and subsurface utilities,
<br /> Y� 3. Figures depicting lithology(cross section), treatment system diagrams; . Boring logs and cross-sections show sand and
<br /> silt with minor clay.
<br /> 0 4. Stockpiled soil remaining on-site or off-site disposal(quantify); No report of excavated soils.
<br /> 5. Monitoring-wells_remaining.on-sites.fate;• One recovery, seven monitoring, four SVE, and two air sparge wells exist on-
<br /> ' s#e The—wells will lie properly destroyed'pending site-closure:
<br /> 0 6. Tabulated results of all groundwater elevations and depths to wafer; Groundwater levels varied from 9 to 17 feet below
<br /> ground surface, and flow has varied from NE to SW. }
<br /> 7. Tabulated results of all sampling and analyses: Maximum groundwater monitoring results for July 2000 in!rg/l show
<br /> Detection limits for confirmation sampling TPHg at 220,benzene at 0.55, toluene at a0.5, ethyl benzene at 3.0,
<br /> total xylenes at 20, and MtBE at 150. Other oxygenates are non-detect
<br /> Lead analyses by 8260B analysis. No indication of lead analysis.
<br /> F7Y 8. Concentration contours of contaminants found and those remaining in soil The lateral and vertical extent of soil
<br /> and groundwater, and both on-site and off-site: contamination has been defined.
<br /> © Latera!and
<br /> Y❑ Vertical extent of soil contamination Groundwater contamination has not been
<br /> Latera!and ��{ Vertical extent of groundwater contamination defined southwest of the site; the current
<br /> 9 NLJ downgradient direction.
<br /> 9.Zone of influence calculated and assumptions used for subsurface A SVE/AS system was operated at the site
<br /> 0 remediation system and the zone of capture attained for the soil and from 9198 to 9199. Consultant reports that
<br /> groundwater remediation system; approximately 1200 gallons of TPHg was
<br /> removed by the remediation system.
<br /> T� 10.Reports 1 information l Unauthorized Release Form QMRs
<br /> F1Boring logs PAR 0 FRP Other(Confirmation Sampling, and Closure Request,312000)
<br /> Y 11.Best Available Technology(BAT) used or an explanation for not using BA T. Remove USTs, SVE/AS,natural attenuation.
<br /> 12.Reasons why background was/is
<br /> Y❑ unattainable using BAT, TPHg,BTEX, and MtBE remain in shallow on-site soil and groundwater.
<br /> 13.Mass balance calculation of substance The consultant estimates that 6 gallons of TPHg remain in vadose zone soils
<br /> treated versus that remaining; near the former USTs. Therefore, approximately 99% of soil contamination has
<br /> been removed.
<br /> 14.Assumptions,parameters, calculations and model used in risk
<br /> assessments, and fate and transport modeling; A risk assessment was not completed.
<br /> 15. Rationale why conditions remaining at site will not adversely Remaining contamination is limited to on-site soil and
<br /> yM impact wafer quality, health, or other beneficial uses;and groundwater.
<br /> .By: Comments: Two 1,000-gallon gasoline USTs were removed from the site in February 1989. Soil and groundwater
<br /> contamination was identified, multiple borings and seven monitoring wells were installed, and a SVE and AS system was
<br /> operated from 9198 to 9199. The consultant estimates that 99%of the soil contamination was removed by the SVE/AS
<br /> system, and TPHg, BTEX, and MtBE constituents were reduced in on-site groundwater monitoring wells. Currently, TPHg
<br /> ate' and MtBE in monitoring well MW-2 are increasing. The groundwater flow direction has varied from northeast to
<br /> southwest, and groundwater monitoring southwest of the site has not been completed. An on-site domestic well is
<br /> approximately 80 feet north of the former USTs. This well has been sampled and analyzed since 1991, and found to be
<br /> non-defect for all constituents including MtBE. Based on the unstable nature of TPHg and MtBE in MW-2, and the lack of
<br /> definition southwest of the site, a No Further Action Required Concurrence is not appropriate at this time.
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