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California "-gional Water Quality ContI Board Central Valley Region _ - �`.,_ 'fir Karl E. Longley,ScD, P.E.,Chair �° • Linda S. Adams Arnold 11020 Sun Center Drive#200_Rancho(ofdoca_California 9 671}61 la Secrercir' !a Phone(9 16)464-3291 •FAX(9 16)464-464S Schwarzenegger h.nrn'nnmen°� Pr olec t http/.wNw.wm aterhoards.ca_e '/centrahallc� Governor 9 October 2008E D - Mr. Donald Rodgers OCf 4 2 0 0 8 11900 South Union Rd. Manteca, CA 95336 ENVIFiuNMEu T HEALTH PE,RPOIT,iSERVISES DOCUMENT REVIEW, THE TRANSMISSION STORE, 515 WEST CHARTER WAY, STOCKTON, SAN JOAQUIN COUNTY(REGIONAL BOARD CASE # 390891) ! re.iewed the RrnSN3 �o �oa), re, ived ? nctoher 2008 from your consultant Shaw Environmental Inc. (Shaw). The Report provides the results of the biosparge pilot testing (air injection) conducted on 5 and 6 July 2008. Groundwater samples were collected on 17 June 2008 prior to the air injection, to establish baseline data for ammonia, biochemical oxygen demand (DOD), chemical oxygen demand (COD), heterotrophic plate count (bacteria). nitrate-nitrite, and orthophosphate. A portable air compressor injected air into one sparge well (SP-1) screened 47' to 49' below ground surface (bgs) in the saturated zone. Depth to water was measured at approximately 19' bgs in select monitoring wells prior to the air injection. Electronic dataloggers were then installed in those monitoring wells to measure and record dissolved oxygen (DO). conductivity, pH, temperature, oxidation-reduction potential (ORP), and water !evel changes every 15 minutes. The first phase of air injection was a step-rate test at air pressures of 10. 15, 30, and 40 pounds per square inch gauge (psig) for at least one hour each. The second phase of air injection was a constant rate test at 20 psig for approximately four hours. During the step test, an air leak was discovered in the connection of the air flow meter to the air line. Consequently air flow measurements taken on 5 July 2008 were considered inaccurate for the 15 and 30 psig runs, as evidenced by reduced air flows (3 to 4 times !ower) at 30 and 40 psig on the following day after the flow meter connection was repaired. The constant rate test showed diminishing air flow rates. declining from 21 standard cubic feet per minute (scfm) to 4 scfm after 4 hours with no change in DO levels in monitoring wells. Une monitoring well (MW-11 D), screened more than 30 feet below the SP-1 screen interval, recorded the highest rise (1.2') in the water level at 15 psig: however, the water !eve! data was considered suspect as monitoring wells closer laterally and vertically to the screened interval of SP-1 reportedly showed from 0.3' to 0.7' rise in water levels during the entire pilot test. The petroleum hydrocarbons vapor concentrations (measured by photo-ionization detector, or PID) in monitoring wells generally declined from a pretest maximum 66 parts per million by volume (ppmv) of volatile organic compounds (VOCs) to non-detect or nearly non-detect, with one exception. The PID measured 260 ppmv of VOCs in vapor well VW-2S at the end of the 10 psig step test, then declined to near non-detect as testing progressed. MW-101 (screened 56'-66' bgs and located 19`from SP-1) showed a DO decrease of 2.4 milligrams per Liter (mg/L) at 30 psig and an increase of 1.4 mg/L fn DO at the highest pressure (40 psig), while in the remaining wells the DO results were unchanged or declining with time. With the exception of MW-101, DO levels generally remained below 2.0 mg/L, which indicates the aquifer is anaerobic and not capable of sustaining aerobic microbial degradation of California Environmental Protection Agencj- Z�- Ren cled Pape)