|
TAB''E 1 - CHECKLIST OF REQUIRED t"(TA
<br /> FOR NO FURTHER ACTION REQUESTS AT UNDERGROUND TANK SITES
<br /> Site Name and Location: Tracy Cold Storage,24500 S. MacArthur Road,Tracy,San Joaquin County
<br /> 0 1. Distance to production wells for municipal, domestic, agriculture, With the exception of the replacement onsite private
<br /> industry and other uses within 2000 feet of the site; well,no municipal or private wells are within 2,000 feet
<br /> of the site. The 2004 abandonment of the former
<br /> onsite private well and the replacement well
<br /> installation were approved by San Joaquin County.
<br /> 2. Site maps, to scale, of area impacted showing locations of former and existing tank Sometime during the 1970's, one
<br /> systems, excavation contours and sample locations, boring and monitoring well elevation unknown-volume gasoline UST
<br /> contours,gradients, and nearby surface waters, buildings, streets, and subsurface was reportedly removed.
<br /> utilities;
<br /> Ya3. Figures depicting lithology(cross section), treatment system diagrams; Site litho/ogy consists of sand,silt and clay.
<br /> The total depth investigated was 45 feet.
<br /> 4. Stockpiled soil disposed off-site(quantity); Approximately 1,600 cubic yards of soil were aerated and reused onsite.
<br /> �Y 5. Monitoring wells remaining on-site, fate; Ten monitoring wells(MW-1 to MW-9,and MW-1A) were installed for this
<br /> investigation. MW-1 to MW-4,and MW-8 were abandoned in July 1998,prior
<br /> to the soil overexcavation. The 5 remaining wells will be abandoned.
<br /> 0 6. Tabulated results of all groundwater elevations and depths to water,- The depth to water varied from 8 to 16 feet.
<br /> Groundwater flow direction is to the northwest.
<br /> aY 7. Tabulated results of all sampling and In 8/94,maximum soil results were: TPHg(16,000 mg/kg), benzene
<br /> analyses: (55 mg/kg), toluene(69 mg/kg),ethylbenzene(210 mg/kg), and xylenes
<br /> (920 mg/kg). Confirmation soil results in 7/98 were: TPHg(13,000 mg/kg),
<br /> Y®Detection limits for confirmation sampling benzene(20 mg/kg), toluene(19 mg/kg), ethylbenzene(160 mg/kg),and
<br /> Lead analyses xylenes(450 mg/kg). Maximum groundwater monitoring results in 8/94
<br /> were: TPHg(52,000 Ng/L),benzene(9,700 Ng/L), toluene(6,900Irg/L),
<br /> ethylbenzene(1,800 Ng/L),xylenes(7,200 Ng/L). In 3/04, maximum
<br /> groundwater monitoring results were: TPHg(870 Ng/L),benzene(25 Ng/L),
<br /> toluene(1.4 Ng/L),ethylbenzene(7.3 Ng/L), and xylenes(3.2 NgIL).
<br /> Y 8. Concentration contours of contaminants found and those remaining in soil
<br /> and groundwater, both on-site and off-site: The extent of contamination is defined by
<br /> ®Y Lateral and ®Y Vertical extent of soil contamination soil borings and monitoring wells.
<br /> Lateral and Vertical extent of groundwater contamination
<br /> Q9. Zone of influence calculated and assumptions used for subsurface Based on the limited extent of
<br /> remediation system and the zone of capture attained for the soil and contamination, an engineered remediation
<br /> groundwater remediation system; system was not required at this site.
<br /> 1f0 10.Reports/information Y❑ Unauthorized Release Form Y1 twenty three QMRs(8/94 to 3/04)
<br /> Y❑ Boring logs 0 PAR Y❑ FRP 19 Other: Sensitive Receptor Survey;Additional Subsurface Inv.
<br /> 11.Best Available Technology(BAT) used or an explanation for not using BAT, Remove UST, overexcavation, and natural
<br /> attenuation.
<br /> Ya12.Reasons why background wasps Decreasing concentrations have been attained at all monitoring wells. Minor
<br /> unattainable using BAT,- soil contamination remains on-site.
<br /> Y
<br /> 13.Mass balance calculation of substance The consultant estimated remaining soil contamination is 1,000 gallons of
<br /> treated versus that remaining; TPHg left onsite. Remaining contaminant mass was not calculated for
<br /> groundwater.
<br /> Q14.Assumptions,parameters, calculations and model A risk assessment was not required.
<br /> used in risk assessments, and fate and transport
<br /> modeling;and
<br /> Y� 15. Rationale why conditions remaining at site will not Soil contamination is limited in extent, and based on 23 quarters
<br /> adversely impact water quality, health, or other of groundwater monitoring showing a decreasing trend in
<br /> beneficial uses. concentrations,contamination is not continuing to/each to
<br /> groundwater. .
<br /> By: Comments: One unknown-volume gasoline UST was removed from the subject site in the 1970's. Contamination was
<br /> JLB reported by a soil and groundwater investigation conducted in 8/94. Ten monitoring wells(MW-1 to MW-9 and MW-1A)
<br /> were installed and groundwater was monitored for 23 quarters. In July 1998,approximately 1,600 cubic yards of soil were
<br /> Date: excavated, aerated, and reused onsite;5 of the monitoring wells(MW-1 to MW-4, and MW-8) were destroyed;and one
<br /> replacement monitoring well(MW-IA)and one deep monitoring well(MW-9)were installed. MtBE was not detected in
<br /> 8/9/04 groundwater. Based on the limited extent of soil contamination and decreasing contaminant concentrations in
<br /> groundwater, Board staff concur with San Joaquin County's Closure Recommendation.
<br />
|