Laserfiche WebLink
' Harding Lawson Associates <br /> 1. GAC Media <br /> GAC is reliable and capable of meeting NPDES discharge <br /> ' requirements. This technology requires low maintenance but does <br /> require significant operating capital to replace the GAC as it is <br /> ' utilized. Because of its high reliability in removing organic <br /> compounds, it is recommended to be incorporated in the treatment <br /> ' system prior to discharge to the storm drain. <br /> 2. Air Stripping <br /> Extraction and treatment with air stripping is not <br /> recommended because systems to scrub effluent air emissions may <br /> ' have associated costs greater than groundwater treatment with <br /> i <br /> granular activated carbon. Mechanical maintenance and permitting <br /> requirements imposed by the San Joaquin valley Unified Air <br /> Pollution Control District (APCD) are factors that contribute to <br /> the costs of air stripping. <br /> 3 . Biological Degradation <br /> ' Although this remedial alternative is cost effective <br /> and a proven technology, it is not capable of attaining NPDES <br /> ' discharge levels by itself. However, when used in series before <br /> GAC, it can effectively lower hydrocarbon concentrations and <br /> ' thereby extend the active life of the carbon units. A small <br /> ' bioreactor unit may be used in conjunction with the carbon <br /> treatment system if the operating expenses are off-set by lower <br /> ' GAC replacement expenses. <br /> t 18 <br />