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<br /> <br />= Utter to Scott Hoover ? February 12. 1999 <br />thick clay liner could occur in as little as 4 days, and the rate of release through the base <br />of the liner could be 1,800 gallons per day. <br />c) Since hazardous constituents could leach into the clay liner, as discussed in item b, the <br />clay may have to be hauled to the landfill for disposal at the conclusion of treatment. <br />Thus increasing the volume of material requiring disposal. <br />d) If a clay liner alone were to be employed, the DMG would require a set of technical <br />specifications for the clay and a quality assurance plan to govern the installation. If a <br />composite liner is installed, the DMG would only require a commitment to use <br />appropriate soil types for the soil liner component, e.g. type GC, SC, or CL soils under <br />the Unified Soil Classification System, and visual/manual classification of the soils <br />installed in accordance with ASTM D 2138, and installation of the geomembrane by a <br />qualified installer in accordance with standard geosynthetics industry practices. <br />The DMG defines a composite liner as a clay liner that is directly overlain by a geomembrane <br />such as high density polyethylene. Composite liners have become the standard baseline <br />component for containment of hazazdous and many types of non-hazardous waste because of <br />their much improved performance over a clay liner or geomembrane alone. Please provide <br />design details for a composite lined treatment cell to be installed if any concentrations of 2,4-D <br />over 10 mg/L are found at the site. The DMG envisions that a clay liner will be installed <br />similaz to the design provided in the SAP amendment and a geomembrane will be instal]ed <br />onto the clay. At the conclusion of treatment of any material stored in the cell, extreme caze <br />will have to be utilized during removal of the material to prevent damage to the liner. Then the <br />geomembrane must either be decontaminated or removed and shipped to the landfill. <br />The DMG concurs that the components of the SAP amendment not discussed in items I and Z above <br />will be effective in delineating the extent of contamination at the site and in mitigating the problem <br />assuming that ground water and surface water contamination is not discovered. If you have any <br />questions about this letter, please do not hesitate to contact me. <br />Sincerely, <br />~ ~; <br />i <br />~r C_ <br />Allen C. Sorenson <br />Reclamation Specialist <br />cc: Greg Lewicki <br />c:\wi ndows\personallbandb?.doc <br />