Objective: Effective application of enhanced in situ anaerobic bioremediation depends primarily on the delivery of appropriate levels of substrate amendments in the subsurface and the development of optimal geochemical conditions for anaerobic biodegradation to occur. The objectives of this project are to (1) better understand the effects that substrate loading rates have on substrate persistence and distribution; (2) determine how control of substrate loading rates affects amendment reactivity and development of optimal geochemical conditions for anaerobic biodegradation; (3) identify substrate loading rates that have adverse impacts on secondary water quality; (4) evaluate the effect of differing substrate types or loading rates on hydraulic conductivity; and (5) use this information to develop practical guidelines for designing and optimizing substrate loading rates and injection scenarios for differing substrate types and for differing geochemical and hydrogeologic conditions. Technology Description: Many different substrate types have been used to stimulate the in situ bioremediation of chlorinated solvents in groundwater. Inadequate substrate loading rates or non-uniform delivery may lead to reducing conditions that are insufficient for complete dechlorination to occur, thereby increasing the potential for accumulation of regulated intermediate degradation products. Conversely, the presence of excessive substrate may result in uncontrolled fermentation reactions, degradation of secondary water quality (e.g., mobilization of metals), and poor utilization of substrate for anaerobic degradation of the contaminants of concern. Given these effects, many enhanced anaerobic bioremediation applications fail to achieve performance expectations or develop unanticipated long-term compliance problems. Determining an optimal substrate loading rate and an effective distribution method is a critical design and operational objective. In this project, investigators will compare techniques used to calculate or design substrate loading rates, conduct and evaluate field process monitoring efforts to optimize injection scenarios, determine the effectiveness and cost of these methods to achieve remedial objectives, and provide the Department of Defense (DoD) with a useful tool for designing and implementing effective amendment strategies. Expected Benefits: The benefits of this project are performance- and financial-based. Failure to meet remedial objectives and potential adverse impacts to secondary water quality affect the ability of DoD to protect human health and the environment. In addition to improving remedy performance, this project has the potential to save millions of dollars by reducing long-term operational and monitoring costs. For many applications, the cost to operate, modify, or monitor system performance over periods of years is often greater than the cost to design and install the system. (Anticipated Project Completion - 2008) Principal Investigator: Mr. Bruce Henry Parsons Corporation 1700 Broadway, Suite 900 Denver, CO 80290 Telephone: (303) 831-8100 Fax: (303) 831-8208 E-mail: bruce.henry@parsons.com DoD Liaison: Ms. Erica S.K. Becvar HQ AFCEE/TDE 3300 Sidney Brooks, Building 532 Brooks City-Base, TX 78235-5112 Telephone: (210) 536-4314 Fax: (210) 536-5989 E-mail: erica.becvar@brooks.af.mil | 
