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TA LE 1 - CHECKLIST OF REQUIREATA
<br /> FOR NO FURTHER ACTION REQUESTS AT UNDERGROUND TANK SITES jf
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<br /> Site Name and Location: Souza II LLC, 612 W. Eleventh St.,Tracy, San Joa
<br /> aquin County
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<br /> 1. Distance to production wells for municipal, domestic, agriculture, Two municipal wells are located within 2,000 feet of
<br /> industry and other uses within 2000 feet of the site; the site: The wells are 400 feet southwest(upgradient) }
<br /> and 400 feet west(crossgradlent).
<br /> EE; 2. Site maps, to scale, of area impacted showing locations of former andexisting tank
<br /> From 6/01 to 9101, one 7,800-
<br /> systems, excavation contours and sample locations, boring and monitoring well elevation gallon and one 1,000-gallon
<br /> contours, gradients, and nearby surface waters, buildings, streets, and subsurface gasoline, one 1,000-gallon
<br /> utilities; kerosene, and one 7,500-gallon
<br /> I diesel USTs were removed.
<br /> 3. Figures depicting lithoiogy(cross section), treatment system diagrams; Site lithology consists of sand,silt and clay.
<br /> The total depth investigated was 20 feet.
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<br /> N 4. Stockpiled soil disposed off-site(quantify); The amount and fate of soil removed was not reported.
<br /> Y 5. Monitoring wells remaining on-site, fate;
<br /> Three monitoring wells(MW-1'to MW-3)were installed for this investigation.
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<br /> 0 6. Tabulated results of all groundwater elevations and depths to water, The depth to water varied from 11 to 12 feet. The
<br /> gr_ound�ra
<br /> �- - � ter_flow direction_is_to-_the-n-orth,.at a
<br /> gradient ot'0.005 ft/ft .
<br /> 7.Tabulated results of all sampling and In 2001, confirmation soil analyses reported TPHg(1,700 mg/kg), TPHk
<br /> analyses. (42 mg/kg), benzene(0.009,mg/kg), toluene(3 mg/kg), ethylbenzene
<br /> (10 mg/kg),xylenes(20 mg/kg),MtBE(0.005 mg/kg)and lead(35 mg/kg).
<br /> Detection limits for confirmation sampling Soil borings in 3/04 reported TPHg(290 mg/kg), toluene(0.51 mg/kg),
<br /> ©Lead analyses ethylbenzene(0.6 mg/kg), and xylenes(3.7 mg/kg). Maximum grab
<br /> groundwater results in 2001 were TPHg(13,000 pg/L), TPHd(65,000 Pg/L),
<br /> benzene(24 pg/L), toluenei(80 pg/L), ethylbenzene(95 pg/L),xylenes(280 f
<br /> pg/L),and lead(250 pg/L). !n 3104,maximum groundwater monitoring k
<br /> results were TPHg(150 pg/L), and ethylbenzene(1.2 pg/L). €
<br /> Y� 8. Concentration contours of contaminants found and those remaining in soil ;f fC
<br /> -aud groundwater, both on- ' and off-site: The extent of contamination is defined by
<br /> Y Latera!and Y Vertical extent of soil contamination soil borings, grab groundwater samples,
<br /> Lateral and Vertical extent of groundwater contamination :1 and monitoring wells.
<br /> 0 9.Zone of influence calculated and assumptions used for subsurface Based an the limited extent of
<br /> r; remediation system and the zone of capture attained for the soil and contamination,an engineered remediation i
<br /> groundwater remediation s stem; , system was not required at this site.
<br /> 10.Reports/information Unauthorized Release Form Y❑ nine QMRs''(11/01 to 3104)
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<br /> Y❑ Boring logs N❑ PAR N❑ FRP Y❑ Other: Sensitive Receptor Survey,Additional Subsurface Inv.
<br /> y� 11.Best Available Technology(BAT)used or an explanation for not using BAT,' Remove USTs and natural attenuation.
<br /> 12.Reasons why background was/is Decreasing concentrations have been attained at all monitoring wells. Minor
<br /> unattainable using BAT, soil contamination remains on-site.
<br /> N� 13.Mass balance calculation of substance The consultant estimated remaining soil contamination is 24 gallons of TPHg
<br /> treated versus that remaining; in 145 cubic yards of impacted soils left onsite, and X0.1 gallons of TPHg in y
<br /> groundwater. !
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<br /> 14.Assumptions,parameters, calculations and model A risk assessment was not required. Groundwater modeling
<br /> used in risk assessments, and fate and transport predicted a maximum plume travel distance of 282 feet Boring
<br /> modeling;and SB2 reported no groundwater contamination at 65 feet
<br /> downgradient of source area.
<br /> �! 0 15. Rationale why conditions remaining at site will not Soil contamination,is limited in extent, and based on
<br /> ri adversely impact water quality, health, or other 9 quarters of sampling, contamination is not continuing to leach
<br /> beneficial uses. to groundwater. Groundwater monitoring shows a decreasing
<br /> trend in concentrations.
<br /> J. By: Comments: During site construction grading from 6/01 to 9/01, one 7,800-gallon and one 1,000-gallon gasoline, one
<br /> i 7LB 1,000-gallon kerosene, and one 7,500-gallon diesel US Ts were discovered and removed. Contamination was reported in
<br /> soil and groundwater. Three monitoring wells(MW-1 to MW-3) were installed and monitored for 9 quarters.An additional
<br /> Date: soil and groundwater investigation defined the extent of contamination and confirmed the groundwater fate and transport
<br /> model results, which showed limited plume movement due to natural attenuation. Based on the limited extent of soil
<br /> 7/28104 contamination and decreasing contaminant concentrations in groundwater, Board staff concur with San Joaquin County's
<br /> Closure Recommendation.
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