Washington County Coastal Resilience

As part of a climate resilience initiative funded by the Maine Coastal Program and the Island Institute, WCCOG identified several sites in five communities as having infrastructure vulnerable to coastal flooding due to anticipated sea level rise. SME provided WCCOG with engineering designs and recommendations to strengthen coastal resiliency and improve public safety by providing drainage solutions on roadways, at culvert crossings, and along working waterfronts.

Challenges

In the Gulf of Maine, sea level rise from glacial melting and rising ocean temperatures is expected to increase the frequency and severity of coastal flood events, resulting in greater risk to vulnerable areas. Roadways, stream crossings, and commercial fishing infrastructure already experience coastal flooding during extreme high tides, heavy precipitation, and snowmelt. In one WCCOG town, when the coastal stream floods a residential road, over 50 homes become isolated and inaccessible.

Project Outcome 

SME prepared engineering designs and recommendations to mitigate current and future flooding issues. We gathered National Oceanic and Atmospheric Administration (NOAA) tide gauge data and predictions of sea level rise in Maine. Evaluation of site-specific conditions were enhanced by using hydrological modeling of both stormwater runoff and tidal zone conditions.

Our firm studied the use of living shorelines and coastal structures to adapt design solutions to the specific tidal conditions surrounding the project areas. Shoreline adjacent to coastal wetlands received low-sloped sea grass and vegetation to stabilize the embankment and benefit the local ecosystem by providing wildlife habitat. Shorelines vulnerable to direct wave action and steeper slopes were designed with riprap to dissipate wave energy and provide increased erosion resiliency.

Constructing infrastructure that is resilient to anticipated sea level rise and coastal flooding will save more expensive repair or relocation costs in the future. To minimize immediate costs, design improvements were assessed with respect to heights of sea level rise predictions. Levels of resiliency were designed relative to anticipated sea level rise based on NOAA prediction scenarios from low to extreme cases. One of our designs included a road height increase of four feet and extended the roadway width to allow for future build-up. The Eastport Middle Road project was completed in 2023 as a result of the findings of this evaluation.