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I
<br /> 77�LE 1 -CHECKLIST OF REQUIRED DATA F
<br /> FOR
<br /> O FURTHER ACTION O REQUESTS AT �
<br /> UNDERGROUND TANK SITES r
<br /> Site Name and Location: H&H Engineering and Construction Facility, 212 Industrial Drive, Stockton,Sart Joaquin County
<br /> (LUstis Case#391003)
<br /> Y 1. Distance to production.wells for municipal, domestic, agriculture, A well survey in 2000 reported 6 municipal or
<br /> industry and other uses within 2000 feet of the site. irrigation wells within 2000 feet of the site: 1000 ft
<br /> west, 1600 it southwest; 1800 ft east,i800 ft
<br /> northeast,and 1300 and 1400 ft northwest.
<br /> Y1 2. Site maps, to scale, of area impacted showing locations of any former One 1,000-gallon gasoline UST was:removed
<br /> and existing tank systems, excavation contours and sample locations, without a permit in 1987. A groundwater i
<br /> boring and monitoring well elevation contours,gradients, and nearby investigation for an unrelated SLIC case
<br /> surface waters, buildings, streets, and subsurface utilities; discovered the UST pollution in 3/98.
<br /> 'Yj 3. Figures depicting lithology(cross section), treatment system diagrams; Site lithology consists of clay,silt,and sand
<br /> to 53 feet, the total depth investigated.
<br /> 0,). The fate and amount of soil removed was not specified.
<br /> N 4. Stockpiled soil remaining on-site or off-site disposal(quantity);
<br /> g wells i
<br /> itorn MW-1
<br /> :Yd 5. Monitoring wells remaining on-site, fate; Three mon ( through g MW-3)remaining on-site w!!!be
<br /> ro erly abandoned
<br /> 6. Tabulated results of all groundwater Depth to groundwater varied from 26 to 38-feet below ground surface.
<br /> elevations and depths to water- The groundwater gradient was 0.01 ft/ft and the downgradient direction
<br /> was to the Northeast.
<br /> 7. Tabulated results of all sampling In 2/98, maximum soil concentrations were TPHg,260 mg/kg;benzene, 6.8 mg/kg;
<br /> and analyses: toluene;21 mg/kg;ethylbenzene, 15 mg/kg;and xylenes,34 mg/kg. In 3/05,all soil
<br /> concentrations were ND. Maximum grab groundwater concentrations in 3/98& -
<br /> Detection limits for confirmation 8198 were TPHg, 11,000 ug/L;benzene, 10,000 ug/L;toluene,,250 ug//L;
<br /> sampling ethylbenzene, 290 ug/L;and xylenes, 970 ug/L. In 3/07,all groundwater monitoring
<br /> well concentrations were ND.
<br /> Lead analyses
<br /> LYJ 8. . Concentratibn contours of contaminants found and those remaining in soil The extent of contamination is adequately
<br /> and groundwater, and both on-site and off-site_ defined by soil borings,grab groundwater
<br /> samples,and monitoring wells.
<br /> Lateral and Vertical extent of soil contamination
<br /> Lateral and Vertical extent of groundwater contamination
<br /> NI 9. Zone of influence calculated and assumptions used for subsurface An engineered remediation system was not
<br /> remediation system and the zone of capture attained for the soil and required by the lead agency.
<br /> groundwater remediation system,' I '
<br /> 10.Reports/information ❑Y Unauthorized Release Form [Y QMRs(18 from 10/98 to 3107)
<br /> i
<br /> �Y
<br /> Welland boring logs �Y PAR FRP Other; Sensitive Receptor Survey,-Human Health Risk
<br /> Screening Evaluation;Request for Closure
<br /> Y 11.Best Available Technology(BAT)used or an explanation for not using SAT Removal of UST and natural attenuation.
<br /> I
<br /> Y1 12.Reasons why background warms unattainable using BA T; Limited soil contamination and minimal groundwater
<br /> pollution remain on-site.
<br /> Y 13:Mass balance calculation of substance treated versus that In 2005, the cansultanf estimated 30 galions.of TPHg remain
<br /> remaining; in soil,and 0.7-lbs of TPHg remain.,in groundwater_
<br /> Y 14. Assumptions;parameters, calculations and model used Residual soil contamination does not exceed ESLs. The
<br /> in risk assessments, and fate and transport modeling; Water Quality Goals(WQGs)have been reached. In 8/06 a
<br /> risk assessment did not find a significant risk from residual
<br /> soil contamination and groundwater pollution.
<br /> Y 15. Rationale why conditions remaining at site will not Soil contamination is limited in extent Results of'18
<br /> adversely impact water quality, health, or other beneficial quarters of groundwater monitoring show a decreasing
<br /> uses;and trend in concentrations to ND.
<br /> By: JLB Comments: One 1,000-gallon gasoline UST was removed without a.permit in 1987 from the subject site. A
<br /> groundwater investigation for an unrelated SL1C case discovered the USTpollutlon in 3/98: Twenty borin s
<br /> Date: were advanced and three monitoring wells(MW-1 through MW-3) were installed for the investigation.
<br /> 9/12/2007 Residual sail contamination does not exceed ESLs. The Water Quality Go91s.(WQGs)have been reached. ,
<br /> Soil contamination is limited in extent. Results of 18 quarters of groundwater monitoring'show a decreas ng E
<br /> trend in concentrations to ND. Regional Board staff concur with San Joaquin County's Closure
<br /> Recommendation.
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