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TABL - CHECKLIST OF REQUIRED DA..,% FOR NO FURTHER ACTION REQUESTS AT UNDERGROUND TANK SITES j Site Name and Location: Ripon Milling Company, 320 S. Stockton Ave., Ripon,San Joaquin County Three municipal wells within 2,000 feet. 1. Distance to production wells for municipal, domestic, agriculture, industry Nearest is a non-operational well approx. 500 and other uses within 2000 feet of the site; north (downgradient) of site. © 2. Site maps, to scale, of area impacted showing locations of former and existing tank systems, Two diesel tanks(10,000 and6 Q00 gallons)were removed. excavation contours and sample locations, boring and monitoring well elevation contours, Monitoring well MW 1 was gradients, and nearby surface waters, buildings, streets, and subsurface utilities; installed downgradient of former tanks. Boring logs show sand with varying amounts © 3. Figures depicting lithology(cross section), treatment system diagrams; of silt and clay. Approximately,1450 cy of excavated soil was transported to Y 4. Stockpiled soil remaining on-site or off-site disposal(quantity); the Ripon Police,Department to use for a firing range berm. FT 5.Mbnitbdng wells remaining-on-site;fate; Per.County directive,well MW--1-was:abandoned in April 1.996.. -• �� 6. Tabulated results of all groundwater elevations and depths to water,- Depth to groundwater ranges from 20 feet to 25 feet bgs. Row:direction is northerly. 7.Tabulated results of all sampling and analyses: In June 1995, MW-1 showed benzene(0.6 ppb),toluene(2 ppb),and xylene (1 ppb). TPHg and TPIHd were not detected above the laboratory Detection limits for confirmation sampling detection limits. Lead analyses B. Concentration contours of contaminants found and those remaining in soil Based w two consecutive quarters of and groundwater, and both on-site and off-site: groundwater data'for well earsMW- ,the extent Y Vertical extent of soil contamination of groundwater impact appears to be limited Lateral and to area of former tanks. ELateral and _Vertical extent of groundwater contamination 9.Zone of influence calculated and assumptions used for subsurface A remediation system was not operated at remediation system and the zone of capture attained for the soil and the site. NA groundwater remediation system; 10.Reports/information 9 Unauthorized Release Form F QMRs(Dates) ❑ Well and boring logsPAR FRP FN1 Other(report name) ITIY 9-1. i 1..Best Available Technolpgy.(BAT)used or an explanation for not using BA Tanks were removed, and impacted soil was - - ;. overekdavateif=Natural attenuation will j;achieve water quality objectives. Low concentrations of benzene,toluene,and xylene remain 12.Reasons why background was/is unattainable using BAT; in groundwater.. 13.Mass balance calculation of substance treated versus that remaining; Amass balance was:not presented. NA '. 14.Assumptions,parameters, calculations and model used in risk No risk assessment was performed. NA assessments, and fate and transport modeling, 15.Rationale why conditions remaining at site will not adversely The bulk of impacted soil was removed. Only low levels of impact water quality, health, or other beneficial uses;and benzene, toluene, and xylene were detected in groundwater downgradient of the former tanks. iL 16.WB' or TCLP results No WET or TCLP analyses were performed. NA si By: QNComments: No further action is warranted. Because background water quality is polluted with TCE and its associated constituents, any further investigation and/or remediation with regard to the former Date:/ underground storage tanks would not result in additional benefit.'!Because there is no indication that 11/13/00 gasoline fuel was stored in the tanks, County did not require testing for MTBE. al