SITE INFORMATION AND CORRESPONDENCE

Home Browse Search

TABS 1 - CHECKLIST OF REQUIRED tFXTA FOR NO FURTHER ACTION REQUESTS AT UNDERGROUND TANK SITES Site Name and Location: University of the Pacific, 1081 Mendocino Avenue, Stockton, San Joaquin County ETI 1. Distance to production wells for municipal, domestic, agriculture, There are no private or municipal wells within 2,000 industry and other uses within 2000 feet of the site; feet of the site. Ya 2. Site maps, to scale, of area impacted showing locations of former and existing tank One 4,400-gallon unleaded systems, excavation contours and sample locations, boring and monitoring well elevation gasoline UST was removed on contours, gradients, and nearby surface waters, buildings, streets, and subsurface 4/7/2000. utilities; 3. Figures depicting lithology(cross section), treatment system diagrams; Site lithology consists of sand,silt and clay. The total depth investigated was 38 feet. P4. Stockpiled soil disposed off-site (quantity); Soil excavated from tank pit was used as backfill. FY 5. Monitoring wells remaining on-site, fate; Four monitoring wells(MW-1 to MW-4) were installed for this investigation. The 4 wells will be abandoned. 0 6. Tabulated results of all groundwater elevations and depths to water; The depth to water varied from 11 to 13 feet. Groundwater flow direction varied from south to northeast. 7.Tabulated results of all sampling and In 4/00, maximum confirmation soil results were:xylenes(0.007 mg/kg), lyses: TBA (0.48 mg/kg),and MtBE(15 mg/kg). Boring soil results in 5/00 were: YMtBE(11 mg/kg). Grab groundwater results in 5/00 were:MtBE Detection limits for confirmation sampling (1,300 Ng/L). In 3/04,maximum groundwater monitoring results were: Y Lead analyses MtBE(<5.0 Ng/L). 0 8. Concentration contours of contaminants found and those remaining in soil and groundwater, both on-site and off-site: The extent of contamination is defined by PLateral and ®Y Vertical extent of soil contamination soil borings and monitoring wells. Lateral and Vertical extent of groundwater contamination 0 9. Zone of influence calculated and assumptions used for subsurface Based on the limited extent of remediation system and the zone of capture attained for the soil and contamination, an engineered remediation groundwater remediation system; system was not required at this site. Q10.Reports/information IT] Unauthorized Release Form 19 four QMRs(1/02 to 4/03) 0 Boring logs El PAR N❑ FRP Y❑ Other: Add. Subsurface Investigation, Add. GWAssessment 11.Best Available Technology(BAT) used or an explanation for not using BAT,' Remove UST and natural attenuation. Q12.Reasons why background wash's Decreasing concentrations have been attained at all monitoring wells. Minor unattainable using BAT soil contamination remains on-site. Q13.Mass balance calculation of substance The consultant did not estimate remaining soil or groundwater contamination treated versus that remaining; left onsite. 14.Assumptions, parameters, calculations and model A risk assessment was not required. used in risk assessments, and fate and transport modeling;and 15. Rationale why conditions remaining at site will not Soil contamination is limited in extent,and based on 4 quarters of adversely impact water quality, health, or other groundwater monitoring over 2 years, MtBE shows a decreasing beneficial uses. trend in concentrations, contamination is not continuing to leach to groundwater. . By: Comments: One 4,400-gallon unleaded gasoline UST was removed on 4/7/2000 from the subject site. Contamination JLB was reported in soil and groundwater. In 4/00, maximum confirmation soil results were:xylenes(0.007 mg/kg), TBA (0.48 mg/kg), and MtBE(15 mg/kg). Boring soil results in 5/00 were:MtBE(11 mg/kg). Grab groundwater results in 5/00 Date: were:MtBE(1,300 Ng/L). In 3/04, maximum groundwater monitoring results were:MtBE(<5.0 pg/L). The extent of contamination is defined by soil borings and monitoring wells. Based on the limited extent of soil contamination and 10/5/04 decreasing contaminant concentrations in groundwater, Board staff concur with San Joaquin County's Closure Recommendation.