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NHDOT Derry – Londonderry Exit 4A Interchange

Case Studies

Client: Fuss & O’Neill

Project Highlights:

  • Demonstration of project compliance in a TMDL-protected watershed
  • Successful wetlands/USACE 404 permitting
  • Project compliance with rare, threatened, and endangered species regulations

Services Provided:

  • Environmental resource evaluations and permitting
  • Rare, threatened, and endangered species assessments
  • Natural resources mitigation planning

To reduce congestion and improve safety along NH 102 and promote economic vitality, Derry, Londonderry, and the New Hampshire Department of Transportation (NHDOT) proposed a new highway interchange on I-93 (Exit 4A) between Exits 4 and 5. Normandeau provided multiple years of comprehensive environmental support for the project including water resources evaluations, stream surveying, wetlands and vernal pools mapping and permitting, botanical surveys, wildlife assessments, threatened/endangered species compliance, and hazardous materials assessment. One unique aspect of the project was the potential presence of northern black racer snakes (Coluber constrictor) and their hibernacula (where they hibernate) in the vicinity of the project site. Normandeau is one of the few pre-qualified firms trusted by the New Hampshire Fish and Game Department (NHFG) to complete effective field surveys for this state-listed threatened species. Normandeau performed field surveys within the approximately 40-acre survey area along the proposed connector road portion of the Exit 4A project. The black racer survey included consultation with the NHFG regarding the survey protocol and survey area, the procurement of a wildlife permit from NHFG for handling rare species, and field surveys for northern black racers and potential hibernacula within the project areas.

Normandeau biologists completed an extensive field survey following the NHFG-approved survey protocols and found no Black Racers in the project area. However, they did find other species of snakes present, as well as potentially valuable Black Racer habitat features. The results of the survey were presented to NHDOT and NHFG and were incorporated into the wildlife mitigation measures developed for project construction and helped to ensure protection of rare, threatened, and endangered species while also allowing the project to proceed as planned. The project has been successfully permitted and as of 2024 construction is proceeding as scheduled.

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