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l TABLEI- CHECKLIST OF REQUIRED DAR FOR NO FURTHER ACTION REQUESTS AT UNDERGROUND TANK SITES Site Name and Location: Former P.E. O'Hair Company, 1102 South Aurora Street, Stockton, San Joaquin County 0 1. Distance to production wells for municipal, domestic, agriculture, A formal well receptor survey was not required. As industry and other uses within 2000 feet of the site; shown in GeoTracker, three wells are located within 2,000 feet,and the closest well is 1,200 feet northwest. 2. Site maps, to scale, of area impacted showing locations of former and existing tank systems, Four USTs were removed excavation contours and sample locations, boring and monitoring well elevation contours, between 11/88 and 2/94. gradients, and nearby surface waters, buildings, streets, and subsurface utilities; Site maps are provided in the Investigation Report. FT3. Figures depicting lithology(cross section), treatment system diagrams; Lithology consists of silt and clay to 39 feet the total depth investigated. 4. Stockpiled soil disposed off-site(quantity); The disposition of excavated soil was not presented. The soils were likely returned to the tank pit excavations. 5. Monitoring wells remaining on-site, fate; Groundwater contamination was not identified, and monitoring wells were not N installed. FN 6. Tabulated results of all groundwater elevations and depths to water; First groundwater was encountered at 32 feet. The estimated flow direction is to the northeast. F7Y 7. Tabulated results of all sampling and analyses: The maximum concentration of contaminants shows TPHg at 14 mg/kg and organic lead at 0.19 mg/kg. All other constituents including MtBE Detection limits for confirmation sampling were non-detect at acceptable detection limits. The results of ©Lead analyses groundwater sampling in March 2002 were also non-detect for all constituents. 0 Y 8. Concentration contours of contaminants found and those remaining in soil Soil samples collected at 5 to 35 feet only and groundwater, both on-site and off-site: showed TPHg in one boring at 20 feet. All Y� Lateral and Y❑ Vertical extent of soil contamination other constituents were non-detect. Five Lateral and Vertical extent of groundwater contamination groundwater grab samples collected were also non-detect for all constituents. 9. Zone of influence calculated and assumptions used for subsurface Based on minor soil contamination at the 0 remediation system and the zone of capture attained for the soil and former UST areas, site remediation was not groundwater remediation system; required. y� 10.Reports/information 9 Unauthorized Release Form M QMRs 171 Boring logs N❑ PAR El FRP Y❑ Investigation Report, 4/02 Y� 11.Best Available Technology(BAT) used or an explanation for not using BAT- The USTs were removed. 12.Reasons why background was/is Minor contamination remains in soil at the former UST areas. The remaining 0 unattainable using BAT; contan,ination does not present a significant threat to groundwater. NE 13.Mass balance calculation of substance Based on the limited soil contamination identified at the former UST areas, a treated versus that remaining; mass balance was not required. 14.Assumptions,parameters, calculations and model used in risk Based on the limited soil contamination identified at the assessments, and fate and transport modeling; former UST areas, a risk assessment was not required. Fl15. Rationale why conditions remaining at site will not adversely Minor contamination remains in soil at the former UST impact water quality, health, or other beneficial uses. areas. The remaining contamination does not present a significant threat to groundwater. By: Comments: The P.E. O'Hair Company formerly operated a plumbing repair business at the site. Four USTs(one 10,000- MH gallon diesel, one 500-gallon and two 2,000-gallon gasoline) were removed from the subject site between 11/88 and 2/94. Tank pit soil samples were non-detect for all constituents;however, the County inspector noted staining and odor from the soil samples and site closure was not granted. Tank pit soil samples were not analyzed for MtBE or other gasoline Date: additives. As directed by Board staff, five borings were completed to 35 feet in 3/02, and soil and groundwater samples 5/28/02 were collected and analyzed for TPHg, BTEX, and fuel oxygenates including MtBE. One soil sample showed TPHg at 14 mg/kg at 20 feet, and all other soil samples and the five water samples were non-detect at acceptable reporting limits. Based on the limited soil contamination and no impact to groundwater, Board staff concur that No Further Action is required at this site.