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Executive Summary:

In early 2017, Jake Aman, representing the Wells National Estuary Research Reserve (WNERR), met with the Cape Elizabeth Public Works Director and Town Planner to talk about culverts. Jake shared aerial photos of culverts located in the Spurwink Marsh where scouring of adjacent habitat areas was evident. He inquired if the town was considering any culvert replacements, in which case WNERR and The Nature Conservancy might be able to partner with the town to promote a habitat sensitive replacement. The outcome of the meeting was a jointly sponsored assessment of major town culverts, including those located in the Spurwink Marsh.

The resulting Culvert and Habitat Assessment Study, funded with a grant from the Maine Coastal Program, is the first town infrastructure evaluation concentrating on culvert infrastructure. Incorporating habitat impacts into the study modernized the town's more traditional approach to infrastructure planning and broadened the perspective for managing stormwater.

The elements of the study were organized by a stakeholder group including town representatives, civil engineers, and habitat experts. Collaboration by these groups promoted sharing of information, broadening of perspectives and more nuanced problem solving.

A comprehensive data base was developed by field visits to the 16 most significant culverts. Data was collected for each culvert using a form designed for the project. A subset of 6 culverts were selected for preliminary hydraulic analyses, conceptual replacement and cost estimates. All culvert analyses included a habitat impact assessment. A discussion about possible road removal also was initiated, and needs further data collection and evaluation.

The assessment identified as the priority for replacement a culvert that was not a high priority prior to the study. The culvert, located at Willow Brook (rather than the typical location under a road) is in poor condition. It is located 200' upstream of the Spurwink Marsh (rated high value for wildlife habitat). Immediately above the culvert are two sewer lines. If there is structural failure of the culvert, in addition to impacts from inevitable stormwater flooding, there may also be impacts from structural failure of the sewer lines.

The study has created several valuable products. It has created a data base for municipal capital improvement planning for culverts. It has identified an immediate infrastructure priority. It has meshed traditional infrastructure management with a multi-level habitat assessment. More broadly, the study has created a culvert assessment model that will guide future infrastructure planning in Cape Elizabeth and is easily adaptable for other municipalities.


This report was prepared for the Town of Cape Elizabeth by Sebago Technics, Inc., the Wells National Estuarine Research Reserve, the Casco Bay Estuary Partnership and the Town of Cape Elizabeth under award CZM NA17NOS4190116 to the Maine Coastal Program from the National Oceanic and Atmospheric Administration, U.S. Department of Commerce. The statements, findings, conclusions, and recommendations are those of the authors and do not necessarily reflect the views of the National Oceanic and Atmospheric Administration or the Department of Commerce.



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