Laserfiche WebLink
Ms. Carol Campagna 2 - 16 January 2009 lk <br /> Shell Stockton Terminal • <br /> 1 <br /> Samples of vapors entering and exiting the treatment system will be collected monthly in 1-liter <br /> tedlar bags and submitted for laboratory analysis. Laboratory analytical results of these <br /> samples will be used to assess vapor destruction efficiency and regulatory compliance with <br /> San Joaquin Valley Air Pollution Control District permit requirements. Shell proposes to collect <br /> vacuum, flow and system temperatures to assess system operation. Extraction well vapor <br /> concentrations and monitoring well vacuum will be measured using field instruments to assess <br /> DPE effectiveness and vacuum radius of influence, respectively. <br /> All vapor and groundwater samples will undergo laboratory analysis by EPA Method 8260B <br /> and 8015M. If necessary, Shell will implement system adjustments, including the installation <br /> and incorporation of additional extraction wells. Shell proposes to review vapor and <br /> groundwater concentration trends and mass removal rates in semi-annual reports. The system <br /> will be operated until cleanup goals are met. Alternatively, if asymptotic levels are observed, <br /> Shell proposes to implement monitored natural attenuation as a final remedial approach. <br /> Our comments are presented below. <br /> 1. The RAP states that Shell would like to consider re-injecting treated groundwater into the <br /> heart of the plume as an alternative to discharging to the City of Stockton sewer. The RAP <br /> states that for this option, Shell wants to enroll in Waste Discharge Requirements (WDRs) <br /> Order No. R5-2003-0044, General Order for Land Disposal of Groundwater or Surface <br /> Water from Cleanup of Petroleum Pollution, and negotiate higher discharge limits based on <br /> discharging back into the polluted groundwater. Regional Water Board staff is checking <br /> with our counsel to determine if it is possible to negotiate different discharge limits for this <br /> general order, and we will notify you when we receive an answer. A more feasible disposal <br /> alternative to the sewer discharge might be exportation to the Martinez refinery for <br /> treatment and disposal, as Shell proposed during the 14 December 2007 teleconference. <br /> 2. We encourage Shell's efforts to evaluate the use of AS/SVE concurrently with DPE <br /> implementation. However, we cannot consider any requests to delay implementation of a <br /> remedy that has been determined to be feasible because the cost of treated water disposal <br /> for that remedy may increase. Regional Water Board staff may concur with the <br /> implementation of AS/SVE, if Shell can show that this technology is superior to Shell's <br /> current proposed groundwater remedy. However, the data needed to make this <br /> determination might need to be obtained using the same time-consuming process that was <br /> used to select DPE. Until such studies demonstrate that AS/SVE is more viable, Shell must <br /> proceed to implement its selected remedy in accordance with the RAP. <br /> 3. The RAP states that vapor concentrations entering and exiting the treatment system will be <br /> collected monthly in 1-liter tedlar bags and submitted for laboratory analysis. The RAP also <br /> states that groundwater sampling intervals also have not yet been determined. To <br /> accurately track mass removal trends, treatment system sampling is typically conducted <br /> weekly for the first month of operation and monthly thereafter. Regional Water Board staff <br /> requests that Shell set the vapor and groundwater sampling schedules accordingly. <br /> 4. Regional Water Board staff concur with Shell's proposal to pursue system adjustments in <br /> the event that low or asymptotic mass removal rates are encountered. These would include <br /> the installation and incorporation of additional extraction wells. Other optimization <br />