Laserfiche WebLink
-- 27 June 1996 <br /> AGE-NC Project No. 95-0118 <br /> Page 18 of 23 <br /> -. points had occurred. A lower injection pressure, approximately 12 psi, combined with the procedure <br /> of surging the'injected air should be used at the site to minimize the effects of air channeling and <br /> promote maximum interaction of injected air with ground water. <br /> Dissolved iron was not detected in the water sample collected at the site. Therefore, clogging of the <br /> sparging point and formation of pore space should not occur due to iron precipitation. <br /> 8.1.5. DURATION <br /> Air sparging in highly permeable aquifers generally results in rapid reduction of hydrocarbon <br /> concentrations in the saturated zone. Based upon the inferred overall high permeability of soil at the <br /> site (sandy), IAS will probably proceed relatively rapidly. <br /> Based upon dissolved hydrocarbon concentrations currently present in ground water at the site and <br /> i. experience at other sites, we estimate a remediation period of 6 to 18 months. <br /> 8.2. GROUND WATER EXTRACTION <br /> 8.2.1. BASIC PRINCIPLES <br /> There are several different methods for treatment of extracted ground water, which are collectively <br /> called"pump and treat". As the name indicates, all methods involve extraction and.transfer of <br /> contaminated ground water from the aquifer to an above-ground treatment or disposallrecycling <br /> apparatus. The extraction is performed using an automatic pump system to maintain capture <br /> characteristics in the aquifer and to assure process volume requirements are maintained. After <br /> -' treatment, the water is usually discharged into a storm drain or sanitary sewer. A waste discharge <br /> ,. permit is usually required for discharge of the treated water. <br /> I- 8.2.2. TREATMENT METHODS <br /> l�>_{ <br /> The documented presence of hydrocarbons will require treatment for the recovered water. Two of <br /> the most common methods of water treatment are air stripping and carbon adsorption. Air stripping <br /> involves removal of volatile organic compounds from ground water by promoting the transfer of <br /> contaminants from the dissolved phase to the vapor phase. Carbon adsorption utilizes granular <br /> activated carbon to simply "filter" organic compounds out of ground water. <br /> A third, but less common method of above-ground treatment of water is bioremediation. <br /> i <br />