Laserfiche WebLink
' June 1999 <br /> i� E-NC Project No 97-0290 <br />' Page 20 of 26 <br /> 8 2 GROUND WATER EXTRACTION <br />' Ex-situ methods of addressingh drocar <br /> hydrocarbon-impacted ground water involves bunging the impacted <br /> water to the surface and treatment to remove the hydrocarbons prior to ultimate disposal of the water <br /> 8 2 1 Basic Principles <br /> There are several different methods for treatment of extracted ground water, which are collectively <br /> I 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 disposal/recycling <br /> facility The extraction is performed using an automatic pump system to maintain capture <br /> characteristics in the aquifer and to assure that 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 <br />�. 8 2 2 Treatment Methods <br /> The documented concentrations of hydrocarbons will require treatment for the extracted water Two <br /> of the most common methods of water treatment are air stripping and carbon adsorption Air <br /> stripping involves removal of volatile organic compounds from ground water by promoting the <br /> transfer of contaminants from the dissolved phase to the vapor phase Carbon adsorption utilizes <br /> granular 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 />' Contaminated ground water is "treated" by adding hydrocarbon-degrading microbes or by <br /> augmenting natural hydrocarbon degradation activities with the introduction of nutrients <br /> I8 2 3 Feasibility b lity Studies <br /> Aquifer testing has not been performed at the site Site-specific testing would have to be performed <br /> prior to initiation of a pump and treat method The clay layer present beneath the site at 60 feet bsg <br /> would help confine extraction to the upper zone of impacted water Ground water extraction will <br /> create a cone of depression,allowing treatment by vapor extraction of currently submerged impacted <br /> soil <br /> There are several disadvantages to "pump and treat' methods, which include l extended cleanup <br /> . ) P <br /> periods,resulting in increased total costs,although the maintenance for this method is relatively cost- <br /> Advanced CeoEmironmenlal,Inc <br /> I <br />