The objective of this Statement of Need (SON) is to develop solvent alternatives used in various processes for maintenance of Department of Defense (DoD) assets that minimize environmental hazards and occupational exposures. Proposals should identify a particular solvent application in the DoD, quantify the annual usage of that solvent, and explain how the proposed alternative will be more sustainable.

The solvent alternative should have the following general characteristics:

• Eliminate the use of chemicals with risk evaluations under TSCA¹ for a targeted application.
• Reduce or eliminate the use of emerging chemicals of concern² or other chemicals or materials that have been the subject of extensive replacement and/or cleanup efforts.
• Reduce or eliminate hazardous air pollutant (HAP) content.
• Reduce or eliminate volatile organic compound (VOC) content.
• Maintain low flammability or reduce flammability.
• Reduce the risk of harmful workplace exposures and the need for personal protective equipment (PPE).
• Cause no damage to or degradation of the substrate material.
• Be relatively safe with lower toxicity relative to the incumbent solvent.
• Be scalable and relatively cost effective.

Additional specific characteristics for targeted DoD application should be identified in the proposal, the rationale for the alternatives to meet those requirements should be provided, and the work to develop the solvents to meet those requirements should be proposed. Example key requirements including repainting effectiveness (time required and percent removal) and no increases in susceptibility to hydrogen embrittlement.

The DLA ASSIST Tool can be used to download relevant specifications: https://assist.dla.mil/online/start/. For solvent uses where there are no governing specifications, key performance requirements should be identified, and the alternatives should be tested relative to the baseline.

Proposals should hypothesize fundamental reasons for the efficacy of the proposed solvent alternative, propose methods to assess its effectiveness, and propose and assess the solvent alternative formulation(s) that would result in improved performance.

Proposals should include a plan to conduct a Sustainability Analysis³ appropriate to the technology readiness level of the research and development activities being performed to identify and evaluate the solvent alternative. Proposals should establish a lifecycle framework that can mature as the technology or process advances through the acquisition process. This tiered approach aims to develop and document a minimum data set at each stage of research and development that can be used to make informed decisions and streamline transition to an acquisition program. The Sustainability Analysis may include varying depths of data and information that can inform: the goal and scope of an analysis; the identity and quantity of relevant inputs and outputs to the system; and the estimation of life cycle impacts and costs.

Identifying and developing alternatives to currently used solvents would reduce supply risk to DoD operations and lead to improved process sustainability, including reduced time and costs associated with personal protective equipment usage and facility controls. Reducing hazardous emissions can also enable increases in production throughput to enable increased readiness. Program Managers, installations, workers, and warfighters across all services would benefit from new, innovative and improved solvent systems for key defense applications.

Solvents are used in various aspects of the maintenance cycle, including cleaning and surface preparation, application, and removal of adhesives, sealants, and coatings. Solvent usage is applied to small parts, medium-sized parts, and large parts or sections of weapons systems. Cleaning can be performed via dip tank, vapor degreasing, spray applied, or hand applied via cleaning rag. Solvent-based coatings, adhesives, and sealants are applied by spray, caulk tube applicator, and roll on methods. Adhesive, sealant, and coatings are typically governed by military or commercial specification requirements. Solvent-based coating removal can be performed via dip tank, spray applied, or hand applied.

There are a growing number of chemical import, use, and distribution regulations that may impact the long-term availability of chemicals used as solvents in DoD applications. In addition, there are industry guidelines regarding the safe use and transport of these chemicals that represent best practices regarding DoD solvent use. Currently, the U.S. Environmental Protection Agency (EPA) is evaluating the risk of, or publishing risk management rules that may impact the ability to acquire or use a number of chemicals used by the DoD as solvents. Risk management practices that may be required include stricter exposure limits, requiring use of personal protective equipment (PPE) by workers, restrictions on the conditions of use, and/or removal from distribution in commerce of the chemical. These practices represent a significant risk to DoD operations due to the possibility of supply disruptions or making the use of the chemical more difficult or expensive.

Examples of regulated chemicals and chemicals of concern that are used as solvents in relevant industrial operations include methylene chloride, trichloroethene (TCE), tetrachloroethene (PCE), dichloroethene, d-limonene, methyl isobutyl ketone, N-methyl pyrrolidone, benzene, toluene, and xylene among others due to their nature as HAPs or current or potential restrictions on their use. The EPA provides lists of unacceptable, acceptable, and safer chemical alternatives that can be used for these applications.^4,5,6 Various alternatives to chemicals of concern as solvents have been developed, but for some processes, they have not been adopted due to process issues, such as dwell time, scent, line of sight only applications, lack of corrosion inhibitor, wastewater treatment requirements (e.g., d-limonene issues wastewater treatment plants), inability to meet original specification requirements, unacceptably low flash point temperature, and unacceptable lower explosive limits (LEL). Alternative solvents for a targeted application must be compatible with the substrates used. Substrates include steel, aluminum, titanium, or magnesium alloys or polymer matrix composites, depending on the application.

The cost and time to meet the requirements of this SON are at the discretion of the proposer. The two options are as follows:

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 $250,000 and approximately one year in duration. Such proposals may be eligible for follow-on 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.