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TAB'S 1 - CHECKLIST OF REQUIRED DATA
<br /> FOR NO FURTHER ACTION REQUESTS AT UNDERGROUND TANK SITES
<br /> Site Name and Location: McHenry Station, 1405 Main Street, Escalon,San Joaquin County
<br /> Ell 1. Distance to production wells for municipal, domestic, agriculture, A sensitive receptor survey conducted in 8/02 reported
<br /> industry and other uses within 2000 feet of the site; two public supply wells located 1600' N and 1800'SW,
<br /> one domestic well located 1200'W and one irrigation
<br /> well located 750' NE of the site.
<br /> y� 2. Site maps, to scale, of area impacted showing locations of former and existing tank One 10,000-gallon regular and
<br /> systems, excavation contours and sample locations, boring and monitoring well elevation one 5,000-gallon unleaded
<br /> contours, gradients, and nearby surface waters, buildings, streets,and subsurface utilities; gasoline, one 6,000-gallon
<br /> diesel,and one 250-gallon
<br /> waste oil USTs were removed in
<br /> 7/98.
<br /> 3. Figures depicting lithology(cross section), treatment system diagrams; Site lithology consists of sand,silt and clay,.
<br /> The total depth investigated was 52 feet.
<br /> N� 4. Stockpiled soil disposed off-site(quantity); An unspecified amount of soil was excavated,aerated,and spread
<br /> onsite.
<br /> 71 5. Monitoring wells remaining on-site, fate;
<br /> No monitoring wells were installed for this investigation.
<br /> 6. Tabulated results of all groundwater elevations and depths to water; The depth to water is estimated at 57 feet. The
<br /> estimated groundwater flow direction is to the
<br /> northwest. Estimates based on 1405 Escalon Ave.
<br /> 7. Tabulated results of all sampling and analyses: In 7/98, confirmation samples from the USTs excavation reported TPHg
<br /> (3.1 mg/kg), TPHd(9,100 mg/kg),benzene(47 mg/kg),and MtBE
<br /> 8 Detection limits for confirmation sampling (4.4 mg/kg). In 7/98, USTs stockpile soil analyses reported TPHg
<br /> Lead analyses (23 mg/kg), TPHd(18,000 mg/kg),benzene(8.5 mg/kg),and MtBE
<br /> (340 mg/kg). In 12/98 USTs stockpile soil analyses reported TPHd
<br /> (700 mg/kg)and xylenes(6.5 mg/kg)before backfilling the excavations
<br /> (TPHg was not analyzed).
<br /> ED8. Concentration contours of contaminants found and those remaining in soil The extent of contamination is defined by
<br /> and groundwater, both on-site and off-site: on-site soil borings.
<br /> Y® Lateral and ®Y Vertical extent of soil contamination
<br /> Lateral and Vertical extent of groundwater contamination
<br /> a9.Zone of influence calculated and assumptions used for subsurface Based on the limited extent of soil
<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 /> 10.Reports/information q Unauthorized Release Form q QMRs
<br /> El Boring logs ❑ PAR ❑ FRP 71 Other (Report, 9/03)
<br /> M11.Best Available Technology(BAT) used or an explanation for not using BAT,- Remove UST,soil aeration,natural
<br /> attenuation.
<br /> 12.Reasons why background was/is Minor soil contamination remains on-site.
<br /> unattainable using BAT,*
<br /> 0 13.Mass balance calculation of substance The consultant estimated 18 gallons of TPHd and 1.4 gallons of MtBE remain in
<br /> treated versus that remaining; soil down to 14 feet below ground surface at the site.
<br /> Q14.Assumptions,parameters, calculations and model used in risk
<br /> assessments, and fate and transport modeling;and A risk assessment was not required.
<br /> Y� 15. Rationale why conditions remaining at site will not adversely Soil contamination is limited in extent,and based on
<br /> impact water quality, health,or other beneficial uses. maximum depth of contamination(14)and the depth to
<br /> water(over 52'), contamination will probably not reach
<br /> groundwater.
<br /> By: Comments: One 10,000-gallon regular and one 5,000-gallon unleaded gasoline, one 6,000-gallon diesel,and one
<br /> JLB 250-gallon waste oil USTs were removed from the subject site in 7/98.. Multiple borings were completed in 1988 and
<br /> 1989, to delineate contamination at this site. Additional borings were completed between 1996 and 1998. In 7/98,
<br /> Date: confirmation samples in the USTs excavation reported TPHg(3.1 mg/kg), TPHd(9,100 mg/kg), benzene(47 mg/kg), and
<br /> MtBE(4.4 mg/kg). In 7/98, USTs stockpile soil analyses reported TPHg(23 mg/kg), TPHd(18,000 mg/kg),benzene
<br /> 10/21/03 (8.5 mg/kg), and MTBE(340 mg/kg). In 12/98 USTs stockpile soil analyses reported TPHd(700 mg/kg)and xylenes
<br /> (6.5 mg/kg)before backfilling the excavations(TPHg was not analyzed). Based on the limited extent of soil contamination
<br /> and minimal threat to groundwater. Board staff concur with San Joaquin Countv's Closure Recommendation.
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