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4 <br /> L- <br /> 2021¢99-7004 <br /> Lammersvilie School District 20 <br /> July 16, 1990 <br /> Groundwater extraction appears to be a viable remediation technique for this site. A groundwater <br /> treatment system would be needed to treat water prior to discharge. An analysis of treatment options(air <br /> stripping,carbon adsorption,or above-gror. biological treatment)and discharge points(sanitary sewer, <br /> storm sewer, or re-infiltration)would need to be performed. <br /> 9.3 IN SITU BIODEGRADATION , <br /> The remedial action of in situ biodegradation involves the development of a hydraulic control <br /> system similar to the groundwater extraction and treatment method. In addition, a site-specific nutrient <br /> mix is developed to increase hydrocarbon utilizing microbe populations in the groundwater. The nutrients <br /> are introduced through the soil and into the groundwater through a well or infiltration gallery to stimulate <br /> the growth of the hydrocarbon-utilizing microbes. Oxygen is supplied through the use of an oxidizing <br /> agent. The advantages and disadvantages of in situ biodegradation are outlined below: <br /> In situ Bfode radation Advanta es <br /> 1. Treatment of the dissolved hydrocarbons. <br /> 2. Decreases the overall length and cost of remediation project. <br /> 3. Water is infiltrated back into the subsurface, creating a closed-loop system. <br /> In situ Bfode radation Disadvantages <br /> 1. Moderate to high initial <br /> cost to implement system. <br /> 2. Moderate operational and maintenance costs. <br /> 3. Requires continued monitoring and sampling. <br /> 4. Requires permitting for water discharge. <br /> 5. Feasibility study is required. <br /> 6. Potential operation problems include well plugging, nutrient sorption to soils, and poor <br /> oxygen transfer. <br /> At the present time, in situ treatment is not being considered as the primary treatment method <br /> to remediate the site, owi. j to the potential operation problems. However, in situ treatment may be <br /> studied as an addition to a groundwater extraction system. Investigating this treatment option at a later <br /> date would allow time to better understand the site hydraulics (by running the groundwater extraction <br /> system) before nutrients are introduced into the subsurface. Once hydraulic control of the plume is <br /> achieved;and levels of hydrocarbons-reduced,-an in situ feasibility study might be performedto gather <br /> GROUND'vATER <br /> _...�TECHNOLOGY,INC. . <br />