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TAB 1 - CHECKLIST OF REQUIRED DATA
<br /> FOR NO FURTHER ACTION REQUESTS AT UNDERGROUND TANK'SITES .
<br /> Site fame and Location: Tri-Valley Growers-Plant 7, 26200 iVowell Road, Thornton, San Joaquin County
<br /> Y 1. Distance tap
<br /> o production wells for municipal, domestic, agriculture, Seven irrigation wells are located within 1,400 feet of
<br /> �. .
<br /> industry and other uses within 2000 feet of the site; the former UST area. Five wells are owned and
<br /> operated by Tri-Valley Growers.
<br /> Y 2. Site maps, to scale, of area impacted showing locations of former and existing tank systems,
<br /> excavation contours and sample locations, boring and monitoring well elevation contours,
<br /> gradients,and nearby surface waters, buildings, streets, and subsurface utilities;
<br /> Y� 3. Figures depicting lithology(cross section), treatment system diagrams; Borehole lithology and cross section figures
<br /> show predominantly silt, clay,and sand.
<br /> 4. Stockpiled soil remaining on-site or off-site disposal(quantity); Approximately 400 cubic yards of soil was excavated,
<br /> aerated on-site, resampled, and used as backfill.
<br /> 5. Monitoring wells remaining on-site, fate; Seven monitoring wells currently exist on-site. The wells'will be destroyed I
<br /> pending site closure.
<br /> r . :. :� �.-�., sem.•,•w—;......�. _�:,-,�� --
<br /> Q6. Tabulated results of all groundwater elevations and depths to water; Depth to water varies from 3.9'to 13'bgs, and flow
<br /> varies from southwest to northwest.
<br /> 7. Tabulated results of all sampling and analyses:. July 1999 monitoring results for monitoring wells MW-1 through MW-7
<br /> Detection limits for confirmation sampling in pg11 show ND for all constituents(TPHg at<50, MtBE<O.5, all BTEX
<br /> compounds at<0.5). The closest irrigation well(Lopez well)sampled
<br /> ©Lead analyses in July 1999 was also ND for all constituents. z
<br /> 0 Y 8. Concentration contours of contaminants found and those remaining in soil Vertical and horizontal extent of soil and
<br /> and groundwater, and both on-site and off-site: groundwater contamination defined.
<br /> Lateral and Y❑ Vertical extent of soil contamination
<br /> Lateral and Vertical extent of groundwater contamination
<br /> 9. Zone of influence calculated and assumptions used for subsurface Low flow(1.8 to 2.0 liters per minute)
<br /> remediation system and the zone of capture attained for the soil and groundwater extraction and treatment
<br /> groundwaterremediation system; system operated 5191 to 6194.
<br /> 10.Reports/information Unauthorized Release Form FL] QMRs(9189 to 6194, 8197, and 7199)
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<br /> Welland boring logs EIPAR FRP Other(Closure Report, 11199)
<br /> Y 11.Best Available Technology(BAT) used or an g explanation for not using BAT•, Excavated contaminated,solls,pump and
<br /> p
<br /> treat groundwater, monitored natural
<br /> attenuation.
<br /> 12.Reasons why background wasrs
<br /> unattainable using BAT; Impacted soils remain above the water table.
<br /> 13.Mass balance calculation of substance An estimated 555 cubic yards of impacted soils remain on site. Detectable
<br /> treated versus that remaining; hydrocarbons are no longer present in the groundwater.
<br /> N� 14.Assumptions,parameters, calculations and model used in risk A risk assessment was not completed.
<br /> assessments, and fate and transport modeling;
<br /> 0 Y 15. Rationale why conditions remaining at site will not adversely TPHg and BTEX in the most impacted well have dropped
<br /> impact water quality, health, or other beneficial uses;and below the detection limits of 50 pg1l and 0.5 ugA,
<br /> A
<br /> respectively.
<br /> 16.WET qr TCLP results
<br /> By: Comments: Groundwater contamination was remediated to ND by groundwater extraction and treatment followed by
<br /> monitored natural attenuation. The remaining contamination is limited to on-site soils. MfBE and other oxygenates
<br /> have not been identified at this site. The closest water supply well(Lopez well, approximately 150 feet north) was
<br /> Date: sampled in July 1999, and was<DL for petroleum hydrocarbons'and fuel oxygenates. Based on information provided
<br /> •%`i -v ' y the County, the Regional Board concurs with the County's closure recommendation.
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