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HomeMy WebLinkAbout4456 CALIFORNIA AVENUE California Regional Water Quality Control Board. °. Central Valley Region ion Karl E. Longley,Scl), P.E.,Chair Linda S.Adams Arnold Secretaryjor 1685 E Street,Fresno,California 93706 Schwarzenegger Environmental (559)445-5116-Fax(559)445-5910 Governor Protection http://www.waterboards.ca.gov/centralvalley 24 November 2009 111111111111 03 IIIIII�E _ Mr. John Stuart, Jr. Stuart's Petroleum Company 11 41h Street East Bakersfield, CA 93307 CASE CLOSURE - UNDERGROUND TANK LEAK AT FORMER CALIFORNIA AVENUE . MOBIL, 4456 CALIFORNIA AVENUE, BAKERSFIELD, KERN COUNTY This letter confirms the completion of a site investigation and corrective action for the underground storage tank formerly located at the above-described location. Thank you for your cooperation throughout this investigation. Your willingness and promptness in responding to.our inquiries concerning the former underground storage tanks are greatly appreciated. Based on the information in the above-referenced file and with the provision that the information provided to this agency was accurate and representative of site conditions, this agency finds that the site investigation and corrective action carried out at your underground storage tank site is in compliance with the requirements of subdivisions (a) and (b) of Section 25296.1.0 of the Health and Safety Code and with corrective action regulations adopted pursuant to Section.25299.3 of the Health and Safety Code and that no further action related to the petroleum release at the site is required. A summary of the information in the above-referenced file is included in the Case Closure Summary, a copy of which is enclosed. This notice is issued pursuant to subdivision (g) of Section 25296.10 of the Health and Safety Code. Please contact Mr. John M. Noonan at our office at (445) 5550 if you have any questions regarding.this matter.. Sincerely, 4,�amela�CCreedon Executive Officer Enclosure cc: Ms. Barbara Rempel, SWRCB, UST Cleanup Fund, Sacramento Mr. Howard Wines; Bakersfield-Fire Department, Bakersfield Mr. Mark Magargee, VEIR;-Bakersfield- -- - -- — --- Mr. Howard. E. Heller, Kin Properties, New City, New York I IIIIIII VIII III IIII 04 California Environmental Protection Agency IE �a Recycled Paper California Regional Water Quality Control Board Central Valley Region Karl E. Longley,ScD,P.E.,Chair Linda S.Adams Arnold Secrelaryfor 1685 E Street,Fresno,California 93706 SChwarzenegger Environmental (559)445-5116•Fax(559)445-5910 Governor Protection http://www.waterboards.ca.gov/centralvalley TO: JOHN M. NOONAN FROM: JOHN D. WHITING Senior WRC Engineer Engineering Geologist DATE: 24 November 2009 SIGNATURE: SUBJECT: CASE CLOSURE SUMMARY, UNDERGROUN TANK LEAK AT FORMER CALIFORNIA AVENUE MOBIL, 4456 CALIFORNIA AVENUE, BAKERSFIELD, KERN , COUNTY Background Information Site Investigation The former California Avenue Mobil (site) is on the northwest side of California Avenue between Easton Drive and Mervyn's Place in an area of mixed commercial and residential properties. The site is within and on the western boundary of a large shopping center and is currently operated as a retail tire store. Motor fuel is not currently sold. The site is bounded on the west by office buildings.and on the south by multiple family dwellings (apartments). An underground storage tank (UST) system release was discovered during March 1998 system removals. Total petroleum hydrocarbons as gasoline (TPH-g) up to 44,000 milligrams per kilogram (mg/kg) was detected in soil samples collected beneath three fuel dispensers on two dispenser islands and TPH-g up to,14,000 mg/kg was detected in samples collected beneath the western ends of two USTs. Benzene up to 19 mg/kg, and toluene, ethylbenzene, and xylene up to 1,400 mg/kg were also detected. The fuel oxygenate methyl tertiary butyl ether (MTBE) was detected at up to 1,100 mg/kg by EPA Method 8021. On 13 May 1998, the Bakersfield Fire Department.Environmental Services Division (Fire Department) filed a UST Unauthorized Release (Leak) Contamination Site Report and requested an investigation to determine the extent of the release. Investigation was conducted during November 1999. Five soil borings were drilled and sampled to 40 feet below ground surface (bgs). TPH-g was detected.from 4,000 to 12,000 mg/kg in.two borings and lower concentrations were detected-in two other borings: Benzene up to 6.4 mg/kg and toluene, ethylbenzene, and xylenes up to 13,000 were also detected. MTBE was detected at up to 210 mg/kg in three,borings. The borings were converted into temporary well points as groundwater was encountered at 36 feet bgs. Gasoline constituents were detected in all groundwater samples from the well points. TPH-g up to 110,000 micrograms per liter (pg/L), benzene up to 450 pg/L, and toluene, ethylbenzene, and xylenes up to 20,000 pg/L were detected. TPH-g greater than 10,000 pg/L was detected in three samples. MTBE up to 16,000 pg/L was detected in all samples by EPA Method 8021. MTBE California Environmental Protection Agency Qa Recycled Paper r Former California Avenue Mobil Closure Summary -2 24 November 2009 concentrations in two samples exceeded 1,000 ug/L. As groundwater had been impacted, the Fire Department referred the case to the Central Valley Water.Board by letter of 25 February 2000. Five monitoring wells were installed in the area of the former USTs and surrounding positions during October 2000 and soil samples were collected from the well borings to further define the extent of impacted soil. Five additional wells were installed from 2002 to 2004 to replace dry wells and further define the off-site extent of impacted groundwater. Soil and Groundwater Remediation Full-time soil vapor extraction (SVE) system operation with thermal oxidation effluent control began during June 2003. The system Was converted to catalytic oxidation effluent control during February 2004 after influent vapor concentrations declined form greater than 2,000 parts per million by volume (ppmv) to less than 500 ppmv. The system was converted to granular activated carbon effluent control during October 2004 after further decline in concentration. Intermittent (pulsed) operation began during October 2005. The system was shutdown with Regional Water Board staff concurrence during December 2005. The consultant estimated that 13,029 pounds (2,036 gallons) of gasoline constituents had been removed by the SVE system during 17,010 hours of operation. Four,confirmation soil borings were drilled to 50 feet bgs in the UST release source area during November and December 2006 to evaluate remaining gasoline constituent mass. Twenty-four samples were analyzed for gasoline constituents in the laboratory. TPH-g was detected at 420 and 7.4 mg/kg in two samples collected from one boring. Benzene was not detected. Toluene, ethlylbenzene, or xylenes.were detected in seven samples, usually at less than 1 mg/kg. Three samples with toluene, ethylbenzene, and xylene detections of less than 1 mg/kg were collected from 1 ft bgs and were attributed by the consultant to hydrocarbons in asphalt pavement. MTBE and other fuel oxygenates and lead scavengers were not detected. The consultant concluded that the SVE system had successfully removed gasoline mass from subsurface soil. Groundwater Monitoring Groundwater monitoring was conducted from December 2000 until April 2006. Depth-to-water was initially at approximately 49 feet bgs and declined to approximately 55 feet bgs during August 2001, and monitoring wells subsequently became dry. Water was again present in the original wells after August 2005 from approximately 49 to 56 feet bgs. Depth-to-water in replacement and off-site wells increased from approximately 60 to 85 feet bgs from May 2002 until August 2005 and later, when water was present in all monitoring wells due to rising water elevations. Flow direction has been variable during the monitoring history and would be expected to be toward the south-southeast due to the presence of the Kern River 0.5 miles north of the site. TPH-g concentrations up to 100,000 pg/L, benzene up to 27 pg/L, and MTBE up to 730 Ng/L (confirmed by EPA Method 8260) characterized groundwater beneath the former USTs (source area) during the initial monitoring event. Gasoline constituent concentrations declined_ during the next few quarters as the wells went dry. Gasoline constituent detections were generally confined to the source area and vicinity. TPH-g from 5,400 to 37,000 pg/L, benzene Former California Avenue Mobil Closure Summary - 3 - . 24 November 2009 from 45 to 1,100 pg/L, and MTBE from 54 to 200 pg/L characterized groundwater in the source area from 2002 through 2004. MTBE was not detected after April 2003. Sporadic TPH-g detections up to 7,100 pg/L and benzene up to 47 pg/L characterized source area groundwater after 2004. Gasoline constituents have not generally been detected outside of the source area and vicinity during the monitoring history. During the final April 2006 monitoring event, TPH-g was detected in one monitoring well at 250 pg/L and toluene, ethlylbenzene, and xylenes were detected at less than, 30 pg/L in the same well. Analytes were not detected in other wells. Sensitive Receptors The subject site is a retail tire store in a large shopping center area. Apartments are approximately 180 feet south the former USTs.and dispensers. Water is provided by the City of Bakersfield water.system. Five City of Bakersfield municipal water supply wells are located 'between 1,400 and 2,500 feet from the'site. Pre-Closure Investigation to evaluate human health risk from the remaining effects of the UST release was conducted during 2006, 2008,. and 2009. Shallow soil sampling to evaluate health risk from dermal contact was.conducted during confirmation soil sampling after SVE system shutdown, as discussed above. Toluene, ethylbenzene, or xylenes were detected at 1 ft bgs in four samples at less than 1 mg/kg. Soil gas sampling to evaluate risk from vapor intrusion was initially conducted during February 2008. Vapor samples were collected from permanent sampling points installed to.5 feet bgs. Three sampling points were installed in the former UST release source area (two points at the former dispenser islands, one point at the former USTs) and one sampling point was installed next to the facility building. Low gasoline constituent and volatile organic compound (VOC) concentrations were detected and MTBE, tetraethyl lead,and tetramethyl lead were not detected. The leak detection compound 1,1-DFA was detected from 58,770 to 19,576,436 pg/m3. The. consultant noted that the 1,1-DFA detection indicated dilution of the samples by a leak in the sampling system, but concluded that further investigation was not warranted due to the low gasoline constituent concentrations. Regional Board staff requested that the source of the leakage be identified and repaired and that an additional round of soil vapor sampling be performed, which was conducted during April 2009. The leak detection compound 1,1-DFA was again detected in the vapor samples, but at concentrations approximately one order of magnitude lower. Gasoline constituents and certain VOCs were again detected, but generally did not exceed laboratory reporting levels. Benzene and napthalene were detected. Benzene did not exceed the California Environmental Protection Agency California Human Health Screening Level (CHHSL). The naphthalene concentration detected in one sample exceeded the CHHSL. The consultant concluded that it was not possible to completely eliminate leakage and that the lower 1,1-DFA concentrations did not invalidate the samples. The,consultant recommended that the UST release be closed as a low-risk site, as significant health risk was unlikely. Regional Water Board staff concurs with these recommendations, and note that the naphthalene detection is Former California Avenue Mobil Closure Summary, -4-- 24 November 2009 y anomalous based on the absence or low concentrations of other gasoline constituents. On 4 August 2009, 1 mailed a pre-closure Public Notice to vicinity landowners and tenants. Public comments were not received during the 30-day comment period. Groundwater monitoring'wells were destroyed on 10 November 2009 and I have received a report documenting well destruction. Conclusions I conclude that the gasoline constituents remaining in subsurface soil and groundwater are unlikely to impact the present or future use of groundwater and human health. I estimate that less than 100 lbs. of gasoline constituents remain in soil and are expected to naturally degrade. I recommend that a standard underground tank site closure letter be mailed to the responsible party.