Pearl St - Elmer Brook Culvert Replacement

Department of Ecological Restoration Culvert Replacement Grant

The Division of Ecological Restoration’s (DER) Culvert Replacement Municipal Assistance Grant Program provides funding to applicants interested in replacing an undersized, perched, and/or degraded culvert in an area of high ecological value. The purpose of this funding is to encourage municipalities and other applicants to replace culverts with better designed crossings that meet improved structural and environmental design standards and flood resiliency criteria.  Elmer Brook is South Hadley's only cold water fishery and as such holds high ecological significance. Located at the base of the Mount Holyoke Range, Elmer Brook connects to Bachelor Brook and eventually the CT River. Culvert replacement projects should be designed to facilitate fish & wildlife passage, maintain the natural movement of water and sediment through the stream crossing, and reconnect upstream and downstream habitat. The town was award the DER Culvert Replacement Grant to complete the design work related to an arch structure culvert replacement that meets stream crossing standards. Construction funding will be sought in future years. 

Project Deliverables

Elmer Brook Culvert Base Map

Elmer Brook Geotechnical Report

Elmer Brook Wetland Delineation Report

Elmer Brook Hydraulic and Hydrologic Report 

Summary Memo

Site Description

Pearl Street crosses Elmer Brook approximately 0.3 miles east of the intersection of Rt. 47/Hadley Street and Pearl Street. The location is known to have experienced flooding in the past. The existing structure is a round corrugated metal pipe perched at the outlet. This is partially due to the severe constriction formed by the 6-foot diameter of the culvert. The crossing is undersized for all peak flows assessed under existing and future climate conditions. A large tailwater scour pool has formed as a result of the constriction and the streambanks downstream of the crossing appear to be eroding toward farm fields. Based on aerial imagery it appears that severe erosion may also be occurring upstream of the crossing. The erosion that has occurred has resulted in mobilization of sediment that has been deposited as large sandbars farther downstream.

Proposed Concept

  • Realign the crossing and replace the existing culvert with a bridge, open-bottom arch, or three-sided box culvert with a span of approximately 24 feet to accommodate an estimated future bankfull width of associated with a 20% increase in bankfull flows due to climate change 
    • This will result in a crossing that meets the Massachusetts River and Stream Crossing Standards, which require a span of 1.2 times the stream’s bankfull width. 
  • The proposed culvert replacement design concept will:
    • Provide increased hydraulic capacity to reduce flooding risk and to allow water and debris associated with larger storms to pass.
    • Decrease potential for road overtopping during heavy precipitation.
    • Improve the passability of the structure 
  • Contact landowners upstream and downstream of the crossing to discuss implementation of nature-based bank stabilization solutions for bank erosion, including native riparian plantings:
    • Bank stabilization will limit the loss of existing farmland
    • Nature-based solutions are low cost and require little maintenance.
    • Nature-based solutions provide additional benefits, including improved in-stream and riparian habitat and improved water quality.
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