The objective of this Statement of Need (SON) was to seek proposals for methodologies that can improve our ability to accurately measure, quantify, and/or enhance natural abiotic transformations of contaminants in groundwater. Abiotic transformations that occur in transition zones such as the capillary fringe and deep vadose zone also were of interest. While some of these abiotic transformation pathways have been studied in detail, their quantifiable impact on contaminant attenuation was still not clear, and it was also not clear whether these transformations can be effectively manipulated or enhanced in situ. Therefore, it is of paramount importance to develop and demonstrate methods to measure these processes and to enhance the natural attenuation capacity by optimizing abiotic reactions. Specific objectives include the following:

• Develop methodologies that estimate the contribution and impact of productive abiotic transformation processes on contaminant fate, transport, and toxicity under intrinsic or enhanced conditions.
• Determine requirements for in situ enhancement of abiotic processes considering biogeochemical conditions, substrates or reactive minerals (i.e., magnetite and iron sulfides), assessing both when it is valuable to enhance abiotic processes and ultimately how to enhance these processes in a cost effective way.
• Determine and manage short- and long-term uncertainties and risks associated with processes that can be realistically enhanced.

Proposals may have addressed one or more of the objectives listed above; however, all proposals must have demonstrated how the knowledge developed will ultimately be used to better quantify the impact of abiotic processes on contaminant attenuation, and the potential for enhancing that attenuation during practical in situ applications. Research and development activities at laboratory-, bench-, and field-scale were considered, but work did not necessarily have to culminate in a field-scale effort. Technologies and approaches should have been applicable to a variety of hydrogeologic settings. Proposals focused on the common chlorinated solvents found in groundwater (tetrachloroethene [PCE], trichloroethene [TCE], and their daughter products) and energetic compounds such as RDX were of most interest.

Research in this area should lead to improved conceptual site models, by accounting for both biotic and abiotic attenuation processes, thereby providing better and more cost-effective protection of human health and the environment. Further, low-cost enhancements to ongoing natural attenuation processes may allow greater use of passive site management. Such enhancements would typically have low capital costs, minimal ongoing operational and monitoring costs, and be capable of providing long-term protection over large areas if necessary. The information developed under this SON was needed to: (1) obtain regulatory and other stakeholder concurrence that natural or enhanced attenuation is a viable, protective long-term remedial option; (2) support cost-benefit analyses of different methods for enhancing attenuation at a given site, if needed; and (3) account for fortuitous natural or enhanced attenuation abiotic processes.

In August 2013, the SERDP and the Environmental Security Technology Certification Program (ESTCP) held a Workshop addressing long term management of contaminated groundwater sites. Approximately 60 personnel representing DoD remedial program managers (RPMs), federal and state regulators, engineers, researchers, industry representatives, and consultants attended. Workshop participants developed research needs to more efficiently deal with the long-term management and lengthy restoration of complex sites. Specifically, the group assessed the potential impact of enhanced attenuation, predictive modeling, and long-term monitoring on the management of complex sites. A more detailed description of these issues can be found in the report from the workshop. Proposers are strongly encouraged to review the workshop report for additional detail. (https://www.serdp-estcp.org/content/download/22092/228039/version/5/file/ Groundwater+Workshop+Report_November+2013.pdf)

Research funded by SERDP suggests that some natural processes, if augmented or enhanced, could decrease life-cycle costs by decreasing the remedial timeframe and/or providing a more sustainable approach to long term source and plume management. By developing methods to enhance these processes, the DoD may reduce the life-cycle costs for these large, complex groundwater sites. While some of these processes have been exploited (notably biological reductive dechlorination), some have been understudied. Given these challenges, there is a critical need to develop and demonstrate tools and methodologies needed to estimate and enhance abiotic attenuation mechanisms at DoD contaminated sites. Enhanced attenuation can bridge the gap between active remediation and monitored natural attenuation (MNA) in an effective and environmentally sustainable manner.

SERDP and ESTCP have funded several projects in an effort to understand abiotic transformation processes of different contaminants. Proposers should be familiar with these past projects, which can be found at https://www.serdp-estcp.org/Program-Areas/Environmental-Restoration. Proposed efforts should be complementary and not duplicative of previously funded projects.

The cost and time to meet the requirements of this SON were at the discretion of the proposer. Two options were available:

Standard Proposals: These proposals describe a complete research effort. The proposer should incorporate the appropriate time, schedule, and cost requirements to accomplish the scope of work proposed. SERDP projects normally run from two to five years in length and vary considerably in cost consistent with the scope of the effort. It is expected that most proposals will fall into this category.

Limited Scope Proposals: Proposers with innovative approaches to the SON that entail high technical risk or have minimal supporting data may submit a Limited Scope Proposal for funding up to $150,000 and approximately one year in duration. Such proposals may be eligible for followon funding if they result in a successful initial project. The objective of these proposals should be to acquire the data necessary to demonstrate proof-of-concept or reduction of risk that will lead to development of a future Standard Proposal. Proposers should submit Limited Scope Proposals in accordance with the SERDP Core Solicitation instructions and deadlines.