SITE INFORMATION AND CORRESPONDENCE

Home Browse Search

Mr. Gregory Torlai, Jr • - 3 - • 11 January 2008 H & H Marina gradient from EW-1, and MW-7 is about 10 feet north. MW-12 is about 160 feet upgradient of EW-1. TBA was detected in EW-1 four times between December 2002 and March 2004 at concentrations ranging from 110 ug/L to 990 ug/L. Monitoring in this well was discontinued in favor of extraction system installation shortly thereafter. During the period of system operation from June 2005 to March 2007, however, TBA has been detected in only seven periodically occurring, monthly influent samples. The extraction rate, calculated from June to September 2007, averaged about 0.5 to 0.7 gallons per minute (gpm). This rate is consistent with historical trends. AGE attributes the low extraction rates to an inadequate supply of electrical power. Extracted influent is routed through four in-series 2,000-pound GAC vessels to treat the petroleum hydrocarbons. The treated effluent is discharged to an agricultural drainage ditch located about 60 feet southeast of the treatment system. General NPDES Permit No. CAG915001 states that the discharge shall not cause total dissolved solids (TDS) to exceed 1,000 milligrams per liter (mg/L) or dissolved oxygen (DO) to fall below 7.0 mg/L in the receiving water. Therefore, H & H conducted a weekly receiving water/effluent study of eight parameters including DO, TDS, pH, turbidity, temperature, electrical conductivity (EC), salinity and oxidation reduction potential between 16 May and 7 August to compare the concentrations of these parameters in the discharge to the receiving water. The data are tabulated in Table 6 of the Third QMR and include samples of the effluent and the receiving water at the point of discharge (POD) and at four locations downstream (R-2 through R-5). During this period, the drainage ditch upstream of the POD was dry. During the study period, TDS concentrations in the receiving water ranged from 101 to 975 mg/L, except for one sample which measured 1,197 mg/L. The DO readings in the receiving water ranged from 0.42 to 6.98 mg/L. One sample exceeded 7.0 mg/L. Based on the data, H & H concludes that the ambient conditions of the surface water at the POD have lower DO and higher TDS than the receiving water in the downstream slough. H & H requests a site-specific waiver from compliance with the 7.0 mg/L DO and 1,000 mg/L TDS receiving water requirements. In a 6 March 2007 letter, Regional Water Board staff requested remedial system optimization to address the residual petroleum hydrocarbons in the effluent and in groundwater at MW-2, MW-3 and MW-4. In response H & H submitted the 15 June 2007 Site Optimization Report (Optimization Report), which recommends reconfiguring the electrical system to permit more continuous operation of the extraction pump and increased groundwater extraction rates. In 2007, AGE added microbes to the treatment system to aid with biodegradation of TBA. This appears to have addressed the TBA breakthrough problem. H & H also recommends reductions to the analyte list and monitoring frequency based on the history of NDs for select analytes. The Optimization Report states that no additional extraction wells are being considered at this time. Our comments are presented below. 1. It appears that the September 2007 AGT gasoline release occurred through no culpability on the part of H & H. The release has commingled with the existing plume, which further complicates the ongoing cleanup effort. However, unless the party(s) responsible for the