The Nature Conservancy, in conjunction with the New Hampshire Department of Transportation, is in the preliminary design phase to replace a tidal culvert on Route 1A between Locke Road and Harbor Road. The existing culvert is a 42-inch-span concrete deck supported on dry-laid granite block abutments. CMA Engineers and subconsultants are completing a watershed hydrologic evaluation, hydraulic evaluation of existing culverts, alternatives analysis, and selection of a preferred alternative. The proposed replacement is a 15-foot-span, three-sided rigid frame with concrete headwalls and wingwalls.
Key elements include:
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Hydrologic and hydraulic evaluation to support alternatives analysis and preferred alternative selection
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Stream simulation features, including natural channel materials and stabilized banks with riprap and wetland vegetation
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Design guided by Tier 4 stream crossing standards, coastal lands and tidal wetlands/water standards, and New Hampshire Coastal Flood Risk Guidance documents
