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California 16gional Water Quality Con#1 Board;; <br /> Central Valley Region .` <br /> ya <br /> Karl E. Longley,ScD, P.E., Chair <br /> Linda S. Adams v Arnold <br /> Sun Centcr Jrr e N,2LJ Ranch Cordova. iliforma 9567«61 I <br /> `` 11020 r"r' r` , Schwarzene er <br /> rrrrrnnmrnRr! <br /> Phone(916)464-3-91 I�AX(916)464-4641 gg <br /> hup ANNkvv \catcrhoards.ca.eo0centralvalin 10)CI CJ /� <br /> 28 May 2009kACCC V ED <br /> Mr. Donald Rodgers ENVIR0�k,, <br /> MantteO a, CA 95336South Union Rd. pERM,/r�FSR -A r/y <br /> ES <br /> .DOCUMENT REVIEW, THE TRANSMISSION STORE, 515 WEST CHARTER WAY, <br /> STOCKTON, SAN JOAQUIN COUNTY(REGIONAL BOARD CASE # 390391) <br /> 1 reviewed the Air Sparging and Biosparging Treatability Test Report (Report), received <br /> 19 May 2009 from your consultant Shaw Environmental Inc. (Shaw). The Report was submitted <br /> in response to my 1 December 2008 letter (Letter), which approved the workplan to conduct a <br /> second, longer Biosparging (BioS) and an air sparging (AS) pilot test, since the July 2008 <br /> two day BioS pilot test results were inconclusive. After five days of injecting air into the aquifer <br /> in BioS mode at an air pressure of 20 pounds per square inch gauge (psig), Shaw modified the <br /> test procedure to begin the AS mode, due to the BioS minimal (0.2 milligrams per Liter, or mg/L) <br /> increase of dissolved oxygen (DO) in groundwater detected at only one well (VW-1 D), and <br /> because no petroleum hydrocarbons were detected in wellhead vapor samples from test- <br /> specific site wells. In contrast to the BioS test. results of the AS test show DO levels increased <br /> from 1 .5 mg/L to 4.0 mg/L after three days of injecting air at 40 psig; while DO reached a <br /> maximum 7.0 mg/L after two more days of injecting air at 45 psig. Likewise, wellhead (wells <br /> VW-2S and VW-2D) petroleum hydrocarbons vapor concentrations, measured onsite by photo <br /> ionization detector, increased from non-detect at startup of AS to a maximum 350 parts per <br /> million by volume. <br /> Upon completion of the BioS/AS pilot test, four vapor samples were collected in Summa <br /> canisters from four wellheads. The maximum laboratory vapor sample results were total <br /> petroleum hydrocarbons as gasoline (TPHg), 37,000 micrograms per cubic meter (Ug <br /> /I-f-13), <br /> benzene. 1 ,700 ug/m3, and xylenes, 2,300 ug/m3. Post-pilot test groundwater sample results <br /> from well VW-2D reported a 20% to 50% reduction in TPHg, benzene, toluene, ethylbenzene, <br /> and xylenes concentrations, while groundwater concentrations generally increased (up to <br /> 600%) in the water sample from well 81; when the data were compared to the first quarter 2009 <br /> groundwater monitoring data. However, all post-pilot test groundwater results were within the <br /> range of historical groundwater monitoring results from the previous four quarters. A post-pilot <br /> test oxygen consumption test, conducted to see if biological activity was consuming DO after <br /> shutdown of the air injection, showed no reduction in DO levels (7 mg/L) measured at well 81 <br /> after 120 hours. <br /> The Report recommends submittal of a remediation well installation workplan and design <br /> specifications for a full scale soil (soil vapor extraction, or SVE for capture of petroleum <br /> hydrocarbon vapors off-gassing from the aquifer to the vadose zone) and groundwater (AS) <br /> treatment system, to be included in a Final Remediation Plan. Additional AS wells (up to ten <br /> total) would be installed to supplement the one sparge well used in the pilot study, and the <br /> California Environmental Protection AgencY <br />