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CHECKLISDATA
<br /> FOR NO FURTHER ACTION REQUESTS AT UNDERGROUND,UAK SITES
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<br /> Site Name and Location: American Moulding S Millwork Company,280f1 North West Lane, Stockton, San Joaquin County '.
<br /> Y 1. Distance to production wells for municipal, domestic, agriculture, industry The site map shows five active wells and three
<br /> abandoned on-site wells within a 2,000-toot
<br /> and other uses within 2000 feet of the site; II
<br /> radius.. The nearest well(irrigation)Is located
<br /> 500 feet west of the site.
<br /> ❑ 2. Site maps, to scale, of area impacted showing locations of former and existing tanks stems, to 1988,a product line from the
<br /> p p g , y 10,000-gallon diesel tank was
<br /> excavation contours and sample locations, boring and monitoring wellelevation contours; repaired after failing a precision
<br /> gradients, and nearby surface waters, buildings, streets, and subsurface utilities; test. The tank was removed in
<br /> 1993.
<br /> ❑ 3. Figures depicting lithology(cross section), treatment system diagrams;
<br /> No treatment system was used at the site.
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<br /> ❑ 4. Stockpiled soil remaining on-site or off-site disposal(quantity); Approximately 700 cubic yards of Impacted soil was stockpiled,
<br /> aerated,and returned to the tank pit Less than 15 cubic yards '
<br /> remain on site, which is ND for hydrocarbons.
<br /> 5. Monitoring wells remaining on-site, fate; No monitoring wells were installed by American Moulding. However,Dames and Moore
<br /> installed two wells within 100 feet of the former UST to monitor contaminant migration
<br /> from an adjacent site. Groundwater level is 10 feet above the top of the screens.
<br /> ❑ 6. Tabulated results of all groundwater elevations and depths to wafer, During soil borings,groundwater was encountered at 50
<br /> feet bgs, with an estimated northeasterly flow direction.
<br /> In 1993, TP14d, TPNg,and low levels of TEX were detected in soil beneath the
<br /> 7. Tabulated results of all sampling and analyses:
<br /> former UST and product line. Linder the tank, TPNg and TPHd were reported of
<br /> V]Detection limits for confirmation sampling 5.5 mg/kg and 63 rng/kg,respectively. TPNg at 89 mg/kg and TPHd at
<br /> Lead analyses
<br /> 910 mg/kg were detected beneath the product line. In 1994, the tank pit was
<br /> over-excavated to�5 feet bgs,resampfed,and backfilled. In 1999,with the
<br /> exception TPHd,soil and groundwater samples were ND for hydrocarbon,
<br /> including MtBE. TPHd at 110 ug/i was detected in one water sample from
<br /> beneath the product lineldispenser.
<br /> El8. Concentration contours of contaminants found and those remaining in soil
<br /> _Md groundwater, and both -site and off-site:
<br /> Lateral and u Vertical extent of soil contamination
<br /> NA Lateral and NA Vertical extent of groundwater contamination .
<br /> NA 9.Zone of influence calculated and assumptions used for subsurface No remediation system was used at the site.
<br /> remediation system and the zone of capture attained, d for the soil and Impacted soil was removed,stockpiled,aerated,
<br /> groundwater remediation system; and returned to the Tank pit
<br /> ❑ 10.Reports/information yr I• Unauthorized Release Form NA MIRs(Dates)
<br /> ❑Y Welland boring logs PAR NA FRP Other(report name)2129/00 County Closure Summary
<br /> ❑ 11.Best Available Technology(BA T)used or an explanation for not usirmg BA?, The tank was removed and the pit was over-
<br /> excavated.
<br /> NA 12.Reasons why background was/is unattainable using BAT, contaminants were not detected in 1999 soil samples. Minor
<br /> conitamination exists in groundwater.
<br /> 13.Mass balance calculation of substance treated versus that remaining, The estimated mass of diesel removed was 3,200
<br /> pounds.
<br /> NA 14.Assumptions,parameters, calculations and model used in risk
<br /> assessments, and fate and transport modeling;
<br /> a15.Rationale why conditions remaining at site will not adversely impacted soil was removed from the site. The residual diesel in
<br /> impact water quality,health, or other beneficial uses;and does not significantly impact groundwater and should naturally
<br /> attenuate over time.
<br /> N❑ 16.WET or TCLP results.
<br /> gy_ Comments:One diesel tank system was removed from the site inj 1993. Nigh levels of 7PHd and TPHg were detected in soil
<br /> samples from beneath the former tank and product line/dispenser. The tank pit was owar-excavated and subsequent soil samples
<br /> Date: were non-detect for petroleum hydrocarbons. In 1999,soil and g foundwater samples were collected from the subsurface of the
<br /> 13'
<br /> / former tank pit and dispenser island;minor diesel contamination was detected in gromdwater beneath the dispenser. The nearest
<br /> 3 (/ active well to the site is an irrigation well, which is located approximately 500 feet cross-gradient(west). Based on the minimal
<br /> impact to groundwater from the residual diesel contamination and the absence of MtBE at the site, staff concurs with the San
<br /> Joaquin County closure recommendation.
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