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TABLE • CHECKLIST OF REQUIRED DAi
<br /> FOR NO FURTHER ACTION REQUESTS AT UNDERGROUND TANK SITES
<br /> Site Name and Location: Silgan Containers Corporation, 1815 Navy Drive, Stockton, San Joaquin County
<br /> Y 1. Distance to production wells for municipal, domestic, agriculture, No municipal supply wells are located within 2000 feet
<br /> industry and other uses within 2000 feet of the site; of the site. One fire protection well and three private
<br /> supply wells are located 300 feet to the northwest,
<br /> 1300 feet and 1600 feet to the southeast, and 2500 feet
<br /> to the northwest, respectively.
<br /> 2. Site maps, to scale, of area impacted showing locations of former and existing tank One 3,500-gallon chlorinated
<br /> systems, excavation contours and sample locations, boring and monitoring well elevation solvent concrete-lined UST was
<br /> contours, gradients, and nearby surface waters, buildings, streets, and subsurface utilities; removed in October 1986.
<br /> Y� 3. Figures depicting lithology(cross section), treatment system diagrams; Site lithology consists of silt, silty sand, sand
<br /> and clay to 35 feet, the total depth investigated.
<br /> a4. Stockpiled soil disposed off-site (quantity); Approximately 450 cubic yards of soil was excavated, aerated onsite,
<br /> and replaced into the excavation.
<br /> FY 5. Monitoring wells remaining on-site, fate; Seven monitoring wells (MW-1, MW-2, MW-3, GW-1, GW-2, GW-3, and PW-2)
<br /> were properly destroyed in December 2003.
<br /> 6. Tabulated results of all groundwater elevations and depths to water; The depth to water is approximately 14 feet, and the
<br /> groundwater flow direction varies from northeast to
<br /> southwest at a gradient of 0.005-0.007 ft/ft.
<br /> 7. Tabulated results of all sampling and analyses: in 7/87, TPH as motor oil(57,000 mg/kg), ethylbenzene(6,800 mg/kg),
<br /> xylenes (430,000 mg/kg),paint thinner(84,000 mg/kg),
<br /> Detection limits for confirmation sampling trichloroethylene (TCE, 660 mg/kg), trans-1,2-dichloroethene
<br /> HY Lead analyses (4,500 Ng/L), and cis-1,2-dichlorethene(c1,2-DCE, 8.8 Ng/L) were
<br /> detected in soil. Grab groundwater sampling detected benzene
<br /> (4.9 Ng/L), toluene(T, 25.4 pg/L), ethylbenzene 114 pg/L),xylenes
<br /> (2,890 Ng/L), tetrachloroethene(3.5 pg/L), TCE(472 Ng/L), and vinyl
<br /> chloride(41.3 Ng/L). On 6/03 after 4 consecutive quarters of
<br /> monitoring, results were TPHg(85 Ng/L), TPHd(180 Ng/L),
<br /> ethylbenzene(3.2 Ng/L), toluene(1 Ng/L),xylenes (26 Ng/L), MtBE
<br /> (1.5 Ng/L), and c1,2-DCE(7.4 pg/L).
<br /> FJ8. 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
<br /> Ye Lateral and N
<br /> Vertical extent of soil contamination
<br /> Lateral and Vertical extent of groundwater contamination
<br /> 0 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 /> Y� 10.Reports/information Unauthorized Release Form QM Rs (2/90, 7/01/, 8/01, 3/02,9/02 to 6/03)
<br /> Y❑ Boring logs SIR F FRP FN I Other
<br /> FE 11.Best Available Technology(BAT) used or an explanation for not using BAT,- Remove UST, soil aeration, and natural
<br /> attenuation.
<br /> 0 12.Reasons why background was/is Modeling shows that background will be attained at all monitoring wells within
<br /> unattainable using BAT; 4 years. Minor soil contamination remains on-site.
<br /> 71 13.Mass balance calculation of substance Approximately 0.60 pounds of cis-1,2-DCE remain in groundwater.
<br /> treated versus that remaining,-
<br /> 14.
<br /> emaining,14. Assumptions, parameters, calculations and model used in risk Fate and transport modeling showed limited extent and
<br /> assessments, and fate and transport modeling,and reasonable time to reach Water Quality Objectives.
<br /> Y� 15. Rationale why conditions remaining at site will not adversely Soil contamination is limited in extent after excavation.
<br /> impact water quality, health, or other beneficial uses. Based on four consecutive quarters of sampling,
<br /> contamination is not continuing to leach to groundwater.
<br /> By: Comments: One 3,500-gallon chlorinated solvent concrete-lined UST was removed from the subject site in October 1986.
<br /> JLB Soil contamination (TPHmo and chlorinated solvents) was identified at the UST area. Approximately 450 cubic yards of
<br /> excavated soil from the UST area was aerated onsite, and placed back into the excavation. Multiple borings and seven
<br /> Date: monitoring wells were completed to delineate and monitor contamination at this site. In 6/03, groundwater contaminant
<br /> concentrations declined to 85 pg/L for TPHg, 180 pg/L for TPHd, 1.5 pg/L for MtBE and 7.4 pg/L for c-1,2-DCE. The site
<br /> 3/2/04 will not continue to pose a threat to water quality, human health, and safety within a reasonable period of time.
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