The Challenge
With projected climate change and updated estimates of sea-level rise (SLR) for Massachusetts, it is anticipated that approximately 3,000 culvert and bridge crossings seated at the transition between freshwater and estuarine and tidal transition will be directly impacted by changing conditions. There is a pressing need to identify issues, and further develop guidance within this advancing transition zone, for both ecological benefits (continuity, marsh migration, reducing habitat degradation and loss) and economic benefits (reducing future coastal hazards, flood reduction, coastal erosion, infrastructure failure, etc.). The Stream Crossings in Transition project will facilitate natural resource and infrastructure planning by developing guidance for these transitional stream crossings within near-coastal environments that will experience the impacts of climate change and SLR over the next 50 to 75 years.
Project Scope
This project builds on the Stream Crossings in Transition Phase I work that DER’s Habitat Restoration Branch completed in FY21 and FY22. The intent is to concurrently review, test, and validate the draft Phase I climate resilience guidance developed for stream crossings in coastal and near-coastal environments. In Phase II, a qualified engineering firm will be hired to apply the draft guidance, document the assessment processes, obtain site-specific model data, and develop preliminary designs for up to 3 high priority “transitional” culvert sites. These sites will serve as pilot projects and case studies to help test the draft guidance for transitional crossing replacement and develop technically sound methodology. DER will competitively select sites from crossings identified during Phase I. Selection criteria will include study applicability, project needs, geography, and proximity to Environmental Justice populations. Only municipal crossings will be eligible and only those sites with strong owner commitment will be advanced. Phase II work will provide a value-added benefit by feeding the project development pipeline, while establishing best practices for municipalities located in the coastal zone. The updated assessment and design guidance will be evaluated by the Technical Advisory Committee formed in Phase I; their input will be incorporated into the final work products.
Once finalized, this guidance will be a critical tool for municipalities seeking to replace undersized and degraded culverts in the near-coastal environment. DER will capitalize on its existing culvert replacement technical assistance and capacity building tools and approaches to help coastal communities integrate the new guidance into project prioritization, planning, and implementation. Training modules and materials will be developed in Phase III. Partnership with other state programs, such as EEA’s MVP Program may provide additional avenues for site identification and municipal capacity building.
The goal of this project is to provide restoration practitioners and infrastructure designers with tools that can be used to plan and design structures that have the potential to enhance flood (storm and coastal) resiliency, utilize best practices to prepare for and reduce coastal erosion and scour, and mitigate resource impacts where coastal transportation corridors are critical for health and human safety.
The intended resilience benefits consist of improving habitat conditions across freshwater coastal and estuarine watersheds by identifying and advancing case-study crossings, within these transitional zones and by facilitating the planning, design, and implementation of crossing upgrades that considers improvements for aquatic passage and restored ecological processes (sediment transport, tidal flushing, water quality).
Metrics
The number of site applications received provides an indication of the level of need and interest from communities on how to approach the planning and design of crossings that are predicted to be affected in the 75- to 100-year timeframe, by sea level rise. The number of projects that advance to later phases of design and apply to DER’s Priority Projects Program, MVP, or other funding opportunities will be a good indicator of progress toward raising awareness of the planning process and contributing to the pipeline of projects for all programs.
Results
In September 2023, DER released two competitive Requests for Responses (RFR) seeking (1) up to three transitional crossing sites to accept as sites for preliminary design and (2) a qualified engineering consultant to incorporate site work as case studies and tests that will refine the final Transitional Crossings guidance. A total of 10 sites applied under the RFR, with two sites formally selected via the Site Selection RFR (1). The selected sites, Concord St. Culvert in Gloucester and River Rd. Culvert in West Newbury were notified of their selection in May 2024. Due to time constraints the RFR for a qualified engineering consultant was paused in FY24 with the intent to continue this work in FY25.
Project Alignment with SHMCAP and ResilientMass Plan Priority Actions
This project addresses the following DER actions in the 2018 SHMCAP plan:
- Upgrade Municipal Culverts - Build municipal capacity to replace undersized, deteriorated culverts with larger, safer structures that reduce public hazards, improve ecological health, and increase the climate resilience of human and natural communities.
- Restore Coastal Wetlands - Prioritize, develop, and implement coastal wetland restoration projects that improve ecological health and increase the climate resilience of human and natural communities.
This project addresses the following DER action in the 2023 ResilientMass plan:
- Transitional Crossings Year 1: Testing standards for evaluation, feasibility and design of culverts and bridges that will experience the impacts of sea level rise in the next 50 to 75 years.
Further Action
DER intends to complete the work initiated in FY24 with the support of FY25 ResilientMass funding ($200k). Currently, the engineering RFR is being revised and will be released early FY25, with a competitive selection of a qualified engineer. Preliminary design work for the two sites selected in FY24 will be completed under the resulting contract and will provide case study supporting information to revise the draft to final guidance. Phase III consisting of the development of training modules and materials is targeted for FY26-FY27.