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TA 1 ; CHECKLIST OF REQUIRED TA
<br /> FOR NO FURTHER ACTION REQUESTS AT UNDERGROUND TANK SITES
<br /> Site Name and Location: Pacific Bell, 10 E. 12th Street,Tracy,San Joaquin County
<br /> 0 1. Distance to production wells for municipal, domestic, agriculture, A sensitive receptor survey in 4/03 reported one
<br /> industry and other uses within 2000 feet of the site; private well 600 feet southwest and three municipal
<br /> supply wells 650 feet north of the site.
<br /> 0 2. Site maps, to scale, of area impacted showing locations of former and existing tank One 500-gallon heating oil UST
<br /> systems, excavation contours and sample locations, boring and monitoring well elevation . and one 2,000-gallon diesel
<br /> contours, gradients, and nearby surface waters, buildings, streets, and subsurface utilities;
<br /> UST were removed 2/02 and
<br /> 3/02, respectively.
<br /> 3. Figures depicting lithology(cross section), treatment system diagrams; Site lithology consists of clay. The total depth
<br /> investigated was 23 feet.
<br /> 4. Stockpiled soil disposed off-site (quantity); An unspecified amount of soil was excavated and reused as backfill
<br /> onsite.
<br /> F 7Y 5. Monitoring wells remaining on-site, fate;
<br /> Three monitoring wells(MW-1 to MW-3), installed for this investigation, will
<br /> be properly abandoned.
<br /> 0 The depth to water is 10 feet. The groundwater flow F
<br /> 6. Tabulated results of all groundwater elevations and depths fo water,
<br /> —�--- �-�.=,_ —_ -- ---� —<direction-varied-from-north-to-southwest--_--�
<br /> FY 7. Tabulated results of all sampling and analyses: Maximum soil boring results in 3/02 reported TPHd(5 mg/kg), In 9/02,
<br /> additional soil analyses reported TPHd(2.7 mgtkg). Groundwater
<br /> ® Detection limits for confirmation sampling maximum grab sample from 3/02 reported'TPHd(390 Ng/L). In 10/03,
<br /> Y Lead analyses groundwater samples reported ND for all constituents, including MtBP.
<br /> 0 8. Concentration contours of contaminants found and those remaining in soil The extent of contamination is defined by
<br /> d groundwater, both on-zitp and off-site: soil borings and groundwater monitoring
<br /> Y Lateral and Y Vertical extent of soil contamination wells.
<br /> Lateral and Vertical extent of groundwater contamination
<br /> N� 9. Zone of influence calculated and assumptions used for subsurface Based on the limited extent of soil and
<br /> remediation system and the zone of capture attained for the soil and groundwater contamination, an engineered
<br /> groundwater remediation system; remediation system was not required at
<br /> this site.
<br /> 0 10.Reports/information Y❑ Unauthorized Release Form QMRs, 7/03 to 10/03
<br /> Boring logs Y❑ PAR E FRPY❑ Other Site Conceptual Model(7/02) Closure Report(2/04)
<br /> 11.Best Available Technology(SAT) used or an explanation for not using BAT, Remove UST and natural attenuation.
<br /> 12.Reasons why background was/is
<br /> unattainable using BAT Minor soil contamination remains on-site.
<br /> Q13.Mass balance calculation of substance
<br /> treated versus that remaining; Mass balance was not estimated.
<br /> i
<br /> 14.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
<br /> impact wafer quality, health, or other beneficial uses. 2 ND quarterly sampling events, contamination is not
<br /> leaching to groundwater. Groundwater monitoring
<br /> shows no impact to Water Quality.
<br /> By: Comments: One 500-gallon heating oil UST and one 2,000-gallon diesel UST were removed 2/02 and 3/02, respectively.
<br /> JL,B Multiple borings and three monitoring wells were completed in 2003, to delineate contamination at this site. Maximum soil
<br /> boring results in 3/02 reported TPHd(5 mg/kg)- In 9/02, additional soil analyses reported TPHd(2.7 mg/kg):
<br /> Date: Groundwater maximum grab sample from 3/02 reported TPHd(390 pg/L). in 10/03, groundwater samples reported ND
<br /> for all constituents, including MtBF. Based on the limited extent of soil contamination and two quarters of groundwater
<br /> 3/3/04 analysis, which show no impact to groundwater, Board staff concur with San Joaquin County's Closure Recommendation.
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