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Groundwater Treatment Pilot Plant -2- 15 October 1993 <br /> DDRW, Tracy <br /> 4. Page 4-3, Section 4.2.0.7; This section states that during the 96 hour Prove-out test, the <br /> influent flow meter was clogged and had to be cleaned in order to proceed with the test. Will <br /> this procedure need to be repeated often during full scale operation? If so, are any actions <br /> being taken to remediate this problem? <br /> 5. General Comment; The steady state reinjection capacities of the three injection wells were not <br /> clearly defined as required by section C1 of the WDR. The text should state specifically the <br /> values obtained for each injection well. <br /> Three Month Evaluation Report No. 1 <br /> 1. Page 3-14, Section 3.1.2.6; This section states that the Air Stripper influent and effluent <br /> concentrations of tetrachloroethene (PCE) and trichloroethene (TCE) are graphed with respect <br /> to time in Fig. 3-11. Effluent concentrations are not graphed in this figure and this graph is <br /> not contained in this document. <br /> This section also refers to the non-detect concentration of the air stripper effluent with regard <br /> to PCE and TCE. Since the WDR states that the concentrations of these compounds shall not <br /> exceed 1.0 µg/1, the non-detect concentration should be lowered to a value less than 1.0 µg/1 <br /> since the analytical procedures are not reliably able to quantify results when they are close to <br /> the method detection limit. The EPA method detection limit for these compounds is 0.5 µg11 <br /> and should be reported. However, if the PQL of the specific lab performing the analysis is <br /> lower than 0.5 gg/1, this lower number should be reported. <br /> 2. Page 3-14, Section 3.2.0.7; This section states that chlordane and dieldrin had concentrations <br /> exceeding the California Maximum Contaminant Level (MCL) concentrations. Chlordane has <br /> a primary California MCL of 0.1 1Ag11. The effluent only slightly exceeded this limit in week <br /> 4 of operations (0.106 µg/1). <br /> Pesticides will be evaluated in the Comprehensive Site-Wide Remedial Investigation/Feasibility <br /> Study (RI/FS). Effluent Treatment Standards for dieldrin were established at 0.006 gg/I in the <br /> Operable Unit No. 1 (OU-1) Record of Decision (ROD) signed on 13 August 1993. <br /> Background concentrations of pesticides will be evaluated in the Comprehensive Site-Wide <br /> RI/FS to determine if the regional groundwater quality has elevated concentrations of <br /> pesticides. Effluent Treatment Standards for OU-1 will be reevaluated when this information <br /> is available. The Board is in the process of revising the WDRs for the IRM system to include <br /> the expansion of the IRM to the final groundwater Remedial Action for OU-1. In the <br /> meantime, pesticides in the air stripper effluent need to be closely monitored. <br /> 3. Page 3-18, Section 3.3.1.2; This section refers to the diminished flow rate experienced by the <br /> injection wells due to well screen fouling. An added factor to this diminished flow rate may <br /> be due to the fact that the injection wells IW-1 and IW-3 operated at flow rates exceeding the <br /> design flow of 40 gpm as depicted in Table 2-1, page 2-3. However, since the steady state <br /> reinjection capacities of these wells were not clearly defined in the System Start-up and Prove- <br />