Stormwater Infiltration in the Highway Environment: Guidance Manual

This report from earlier in 2020 is relevant to the latest issue of TR News (#328, on stormwater management).

The infiltration approach to stormwater management involves the design, construction, and operation of engineered systems that infiltrate stormwater runoff into soils. These systems, referred to as “infiltration best management practices (BMPs),” are intended to reduce the volume of stormwater runoff and associated pollutants that discharge to stormwater systems and receiving waters via surface runoff.

The TRB National Cooperative Highway Research Program's NCHRP Research Report 922: Stormwater Infiltration in the Highway Environment: Guidance Manual supports evaluation, selection, siting, design, and construction of infiltration BMPs in the highway environment. It is also intended to identify limitations on the use of infiltration and determine the need for alternative non-infiltration-based stormwater management approaches.

Additional resources for the guide include:

A Power Point presentation summarizing the project

Appendix A: Infiltration BMP Fact Sheets

Appendix B: Infiltration Estimation Method Selection and Interpretation Guide

Appendix C: Roadside BMP Groundwater Mounding Assessment Guide and User Tool (Excel-based tool)

Appendix D: Guide for Assessing Potential Impacts of Highway Stormwater Infiltration on Water Balance and Groundwater Quality in Roadway Environments (Excel-based tool)

Appendix E: Guide to Geotechnical Considerations Associated with Stormwater Infiltration Features in Urban Highway Design

Appendix F: BMP Clogging Risk Assessment Tool (Excel-based tool)

Appendix G: Whole Lifecycle Cost and Performance Example

Appendix H: Example Construction-Phase Checklists for Inspector and Contractor Training