10-10-1988 - Agenda Packet City Council - regular meeting

Home Browse Search

1,4Pumping and Treatment Operations We anticipate relatively low yield from the recovery trench, on the order of one to three gallons per minute. It is likely that the pumping system will operate intermittently. The recovery sump will contain a single 220 Volt, 1 /3 horsepower Grundfos submersible pump. The pump will be equipped with on/off floats to compensate for intermittent pumping. The floats will maintain a drawdown water level in the recovery trench of approximately 17.0 feet. The pump will route contaminated ground water to the surface and into an aeration system for treatment of dissolved volatile constituents. The aeration system will consist of a 220 Volt, three horsepower direct drive blower and two 200 gallon tanks in series. As water enters into the top of the first tank, it is exposed to approximately 350 cubic feet per minute (cfm) of forced air. Water drains from the first tank into the second and receives an additional 350 cfm of forced air. Discharge frorr the second diffusion tank will be directed to the sanitary sewer system (Figure 5). Discharge approval from the MWCC will be obtained prior to installation. The recovery sump and aeration tanks will be enclosed inside a locked wood security fence. 5.5 Recovery Svstem Monitorine and Sampline Proper system operation will be ensured by regular site visits by Delta personnel. We anticipate that a minimum of two site visits will be made during the initial month of operation. Af,:er the initial month, site visits will be conducted every month. Recovery system influent and effluent will be sampled immediately after the system begins operation. After collection of the initial samples, the system will be shut-off until the results are returned and reviewed by Delta, the MPCA, and the MWCC. The system will be activated after approval has been granted by the MWCC to discharge to the sanitary sewe, system. The influent and effluent will be sampled again 30 days after continuous operation begins. Samples will be analyzed for EPA 601/602 parameters. We anticipate that total VOCs discharged to the sanitary sewer system will be less than one part per million (ppm). After the first two rounds of sampling have been completed, we propose quarterly sampling of discharge. We also propose quarterly sampling of welis in the vicinity of the trench system (MW-I, NIW-2, N,!W-2D, MW-6, MW-4. MW-dD, MW-10, MW- I I and MW-12) during the first year of operation. A., other wells at the site will be sampled semi-annually. Reports of discharge sampling will be forwarded to the MWCC and the MPCA. Reports of monitoring well sampling will be forwarded to the MPCA for re,*iew and