The objective of this project was to demonstrate and validate two currently used, publicly available Department of Defense (DoD) green and sustainable remediation (GSR) spreadsheet tools (SiteWise™ and SRT™) and benchmark these tools against an industry accepted Life-Cycle Assessment (LCA) software package (SimaPro®).
SimaPro® is for-purchase software that is widely used for many types of LCA evaluations, but it is not specifically designed for assessment of soil and groundwater remedies. SiteWise™ and SRT™ are publicly available (freeware) spreadsheet-based tools that are specifically designed for soil and groundwater remedies. Comparison of footprints calculated by SimaPro® and the DoD tools were made for the following five sustainability metrics:
- Greenhouse gas (GHG) emissions
- Total energy use
- Nitrogen oxide emissions (NOx)
- Particulate matter emissions less than 10 microns (“PM10” also referred to a “PM”)
- Sulfur oxide emissions (SOx)
In this project, SimaPro® was applied for six demonstration sites that consisted of a total of 20 remedy alternatives. For three of the demonstration sites (Army/Navy installations), consisting of 15 remedial alternatives, the SiteWise™ tool was applied for comparison to the SimaPro® results. For the other three demonstration sites (Air Force installations), consisting of 5 remedial alternatives, the SRT™ tool was applied for comparison to the SimaPro® results. Each tool uses footprint factors (e.g., how much NOx is emitted per gallon of diesel fuel combusted) to convert an input or process into a footprint.
Key findings and conclusions of the demonstration included the following:
- Significant improvements were made to SiteWiseTM and SRTTM as part of this project, with respect to both the calculation of footprints and the usability of the tools.
- In general, all of the tools appear to provide reasonable footprints for sustainability metrics representing GHGs, energy use, NOx, PM, and SOx. It is expected that use of any of the tools to rank footprints for competing remedy alternatives will produce generally similar rankings (though perhaps not the same exact rankings) and provide adequate results for the decisions they are intended to support.
- The results from the DoD tools were not demonstrated to always be within a factor of 1.2 of the SimaPro® results (a performance objective for this project). However, SimaPro® requires the user to select from many potential choices to represent specific remedy items such as materials, transportation, and disposal. This complicates use of SimaPro® as a benchmark because SimaPro® provides varied results (based on user selections) that also differ from each other by more than a factor of 1.2.
- The DoD tools have distinct advantages over SimaPro® with respect to cost, ease of use, and ability to share files for collaboration, peer review, and documentation.
- During the study, a chart was developed to help guide users of the DoD tools in specifying footprint factors for materials that might not be otherwise represented in the tools. This is a significant improvement compared to simply not accounting for those materials.
- The remedy item that contributes most to the footprints depends on the remedy. Electricity use, fuel use, materials, transportation, and disposal were all indicated as the highest contributor for one of the sustainability metrics for at least one remedy alternative.
- Some bias (high and low) is evident when the DoD tool footprints are compared to the SimaPro® footprints. In specific cases where SimaPro® accounts for items that are not accounted for in one of the DoD tools, there is bias towards higher results in SimaPro®. For other items, however, it is not possible to make a general statement regarding systematic bias because SimaPro® results being higher or lower than one of the DoD tools could simply be due to user selections in SimaPro®.
- Although the two DoD tools were not directly compared against each other in this project, based on the demonstration and validation activities performed, there are differences in the footprint factors used to calculate footprints from user inputs.
The results suggest that use of the SiteWiseTM and SRTTM tools should generally be preferred over the SimaPro® tool for DoD projects. SimaPro® would be recommended for cases where outputs for footprints other than those offered by the DoD tools are needed.
It is recommended that future efforts focus on improving standardization between tools used for DoD projects. Based on this demonstration and validation project, efforts to standardize footprint factors are difficult to base on results from SimaPro® and would be better achieved by consensus of experts in the field. Improved consistency between DoD tools would also result from standardizing the sustainability metric for global warming to equivalent carbon dioxide (CO2e). The DoD tools should continue to be improved over time to add any items or processes that are not well represented in the tools.