SITE INFORMATION AND CORRESPONDENCE_CASE 1

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y r— TAS 1 - CHECKLIST OF REQUIREDTA FOR NO FURTHER ACTION REQUESTS AT UNDERGROUND TANK SITES Site Name and Location: Moore Petro., Frank's Exxon#4, 14800 W. Frontage Rd.(Hwy 99), Manteca, San Joaquin Co. FY--1 1. Distance to production wells for municipal, domestic, agriculture, industry Two domestic water supply wells were and other uses within 2000 feet of the site; impacted by site activities.New well completed to 360 feet bgs. 0 2. Site maps, to scale, of area impacted showing locations of former and existing tank systems, Scaled site maps were excavation contours and sample locations, boring and monitoring well elevation contours, provided. Volume contours gradients, and nearby surface waters, buildings, streets, and subsurface utilities; of the.impacted groundwater provided in Closure Report Q3.Figures depicting lithology(cross section), treatment system diagrams; Borings logs were provided. Ya 4. Stockpiled soil remaining on-site or off-site disposal(quantity); Soil aerated on-site and used for grading.Soil anddevelopment water from MW-9 disposed off-site. r--EQ=-&Monitodng wells remaining on-site,-fate;--9 monitoringwells, 2 recovery_Wells, 1 on-site domestic well and.1 off-site. domestic well to be properly destroyed. Q6. Tabulated results of all groundwater elevations and depths to water, DTW historic range from 20.68 to 34.56 feet bgs. 0 7.Tabulated results of all sampling and analyses: Detection limits for confirmation sampling nN Lead analyses a8. Concentration contours of contaminants found and thoselremainingin soil Soil. .01 lbs of 1,2-DCA remaining, with and groundwater, and both on-site and off-site: concentration to 0.0017 mg/Kg. aY Lateral and FYI Vertical extent of soil contamination Groundwater:0.068 lbs of MTBE, 0.032 lbs of 1,2-DCA,and 0.56 lbs of TPHd dissolved aLateral and ny Vertical extent of groundwater contamination in groundwater. 9.Zone of influence calculated and assumptions used for subsurface 7/91 Aquifer test, 10/92 soil vent test FTI remediation system and the zone of capture attained for the soil and groundwater remediation system; a 10.Reports/information Fj Unauthorized Release Form Y❑QMRs(Dates)up to 12/11/97 Closure Monitoring Report 0 Well and boring logs ❑Y PAR 0 FRP RY Other(report name) Cont. Soil Boring Report, Closure Rpt Ra—11:BestAvailable-Technology`(BAT)used or an`e7x—pldn666h'fornot using BAT;- -=Appropriate FS completed- - -� - 0 12.Reasons why background wads unattainable using BAT Low influent concentrations prior to system shut-down. 5yste,removed 2391.8 lbs TPHg and 8.17 lbs benzene 13.Mass balance calculation of substance treated versus that remaining; Remaining(in water):0.068 lbs MTBE,0.032 lbs 1,2-DCA,0.56 lbs TPHd.(in sail:0.01 lb 1,2-DCA Y❑ 14.Assumptions,parameters, calculations and model used in risk Assumptions,param. &calcs provided:Assumptions are assessments, and fate and transport modeling; not as conservative as they could have been,however are likely rep of site conditions,based on sample results 0 15.Rationale why conditions remaining at site will not adversely Fate and Transport model results suggest that no impact water quality, health, or other beneficial uses;and contamination will impact the two domestic wells within the 10 years modeled. NA 16.WET or TCLP results By; Comments:Low concentrations of contamination remain. 1,2-DCA is present in soil and groundwater, adjacent to the former tank location, above the MCL. TPHd and MTBE are above the taste and odor threshold, and MTBE is above Date- the proposed State Action Level in groundwater. The concentrations remaining at the site pose little threat to water 9�3/9� quality. Models suggest that contaminants will riot impact new domestic wells.