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TABS 1 - CHECKLIST OF REQUIRED DATA
<br /> FOR NO FURTHER ACTION REQUESTS AT UNDERGROUND TANK SITES
<br /> Site Name and Location: Libby Owens Ford Company,500 Louise Avenue East, Lathrop,San Joaquin County
<br /> 1. Distance to production wells for municipal, domestic, agriculture, Site is located near Interstate 5 with no public supply
<br /> industry and other uses within 2000 feet of the site; wells within 2000 feet. Two irrigation wells are located
<br /> 1000' SW and 2000'SE of the site.
<br /> 2. Site maps, to scale, of area impacted showing locations of former and existing tank One 5,000-gallon regular,and
<br /> systems, excavation contours and sample locations, boring and monitoring well elevation one 550-and one 5,000-gallon
<br /> contours, gradients, and nearby surface waters, buildings, streets, and subsurface utilities, unleaded gasoline USTs were
<br /> removed in 9/86,4/87,and
<br /> 12/97,respectively.
<br /> 3. Figures depicting lithology(cross section), treatment system diagrams; Site lithology consists of sand,silt and clay.
<br /> The total depth investigated was 16 feet.
<br /> 4. Stockpiled soil disposed off-site(quantity); Approximately 150 cubic yards of soil was excavated, aerated,and
<br /> spread onsite..
<br /> F 7Y 5. Monitoring wells remaining on-site, fate; Two monitoring wells(MW-17 and MW-18)were installed for this
<br /> investigation. The two wells will be properly abandoned.
<br /> 6. Tabulated results of all groundwater elevations and depths to water, The depth to water varied from 10 to 14 feet The
<br /> groundwater flow direction varied from southeast
<br /> to southwest.
<br /> 7. Tabulated results of all sampling and analyses: In 1986-87,soil analyses reported TPHg(49 mg/kg),benzene
<br /> F-71 (2.9 mg/kg),and MtBE(0.006 mg/kg). In 7/03 additional soil analyses
<br /> y Detection limits for confirmation sampling were all ND. Groundwater monitoring results in 11/86 were 5.8 Ng/L for
<br /> Lead analyses TPHg,and 0.1 Ng/L for benzene. In 7/03,groundwater results were ND.
<br /> 8. Concentration contours of contaminants found and those remaining in soil The extent of contamination is defined by
<br /> and groundwater, both on-site and off-site: on-site soil borings and monitoring wells.
<br /> Y® Lateral and ®Y Vertical extent of soil contamination
<br /> Lateral and Vertical extent of groundwater contamination
<br /> 9. Zone of influence calculated and assumptions used for subsurface Based on the limited extent of soil
<br /> remediation system and the zone of capture attained for the soil and contamination,an engineered remediation
<br /> groundwater remediation system; system was not required at this site.
<br /> 10.Reports/information E] Unauthorized Release Form 19 four QMRs(11/86, 5/87, 9/87, and 7/03)
<br /> 0 Boring logs 0 PAR El FRP 0 Other (Reconnaissance Environmental Assessment, 9/87)
<br /> 11.Best Available Technology(BAT) used or an explanation for not using BAT, Remove USTs,soil aeration,natural
<br /> attenuation.
<br /> 12.Reasons why background was/is
<br /> unattainable using BAT, Decreasing concentrations have been attained at all monitoring wells. Minor
<br /> soil contamination remains on-site.
<br /> 0 13.Mass balance calculation of substance
<br /> The consultant did not estimate remaining soil contamination. No
<br /> treated versus that remaining;
<br /> contamination was detected in groundwater in 2003.
<br /> a14.Assumptions,parameters, calculations and model used in risk
<br /> assessments, and fate and transport modeling;and A risk assessment was not required.
<br /> FE15. Rationale why conditions remaining at site will not adversely Soil contamination is limited in extent,and based on four
<br /> impact water quality, health, or other beneficial uses. sampling events, contamination is not continuing to
<br /> leach to groundwater. Groundwater monitoring shows a
<br /> decreasing trend in concentrations.
<br /> By: Comments: One 5,000-gallon regular, and one 550-and one 5,000-gallon unleaded gasoline USTs were removed from
<br /> JLB the subject site in 9/86, 4/87, and 12/97, respectively. Multiple borings and two monitoring wells(Mw-17&MW-18) were
<br /> completed in 1986 to delineate and monitor contamination at this site. Additional borings and grab sampling were
<br /> Date: completed in 1997 and 2003. In 1986 and 1987, maximum soil concentrations reported were TPHg(49 mg/kg),benzene
<br /> (2.9 mg/kg), and MtBE(0.006 mg/kg). In 7/03 soil analyses were all ND for the 12197 UST area. Groundwater monitoring
<br /> 10/22/03 results in 11/86 were 5.8 Ng/L for TPHg, and 0.1 Ng/L for benzene. In 7/03, all groundwater results were ND(<50 to<0.5
<br /> pg/L)for the 12/97 UST area (grab samples)and the monitoring wells. Groundwater flow direction(SW)was confirmed in
<br /> 2003 by resurveying MW-17&MW-18 to existing monitoring wells W-3 and W-4 elevation datum, then taking all water
<br /> levels. Based on the limited extent of soil contamination and decreasing contaminant concentrations in groundwater,
<br /> Board staff concur with San Joaquin County's Closure Recommendation.
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