Scour – Northstar Hydro, Inc.

Tidal Bridge Replacement, Deer Ilse, ME

Northstar provided hydrologic, hydraulic and scour analysis for a replacement bridge at Mill Pond in Deer Isle Stonington. The bridge is affected by tidal flow and runoff to Mill Pond. Daily tides, storm tides and upland runoff all affect water levels and flow dynamics at the bridge. Channel bed at bridge is higher than lowest tide levels creating a lag in tidal inflow and an elevation difference. Deer Isle Tidal Bridge to be Replaced Bed grade at bridge causes a tidal inflow lag and an elevation difference at low tide.

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Skewed Bridge, Madawaska- Edmundston International Bridge, Madawaska, ME

The International Bridge over the St. John River between Madawaska, Maine and Edmundston, New Brunswick is being replaced. Northstar Hydro prepared the hydrology, hydraulics and scour analysis for this bridge replacement, facing the following issues: · Stakeholders represent international team, including MaineDOT, NBDOT, border control for United States and Canada, local residents, paper mill on both sides of the river, and other businesses and interests. · 2-Dimensional flow model employed. · River hydraulics see widely varying flood levels. · Simulation included existing bridge at 90 degree angle to flow and new skewed bridge. · Specific distribution of water levels over…

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Design Build of Six I-95 Bridge Crossings, Hampden, ME

Northstar Hydro teamed with Cianbro and WSP on this design-build project for MaineDOT. The project involved hydraulics of Souadabscook Stream which flowed under all six bridges under varying hydraulic and scour conditions. Project involved very tight timelines, a large project team and effective conveyance of complex information to the larger team with the DB framework.

By nicki_16

Thompson’s Bridge Replacement over Decker Cove, Southport, ME

Northstar Hydro, Inc. provided hydrologic, hydraulic and scour analysis to Maine DOT’s contractor for preliminary design for proposed replacement of the four span Thompson’s Bridge over Decker’s Cove. The project included unsteady flow modeling with model HECRAS and field monitoring to provide data on water elevations, velocities, and rate of flow through the bridge under a variety of storm and daily tide conditions. The bridge is shown in the first photo and the digital terrain model for the hydraulic model is shown in the second photo.

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Landfill bank erosion and river bed restoration, Industrial Client

Northstar Hydro developed a 2-dimensional flow model of a river running adjacent to a non-operational landfill to assess the erosive properties of the river at the landfill embankment and on the river bed. Over the decades, the river has encroached on the riverbank portion of the landfill and in some locations portions of the landfill have been eroded into the river. Considerable amounts of waste coat much of the river bottom in the landfill area. Using the model results, the designer has prepared a conceptual closure plan to remove a portion of the riverbed sediment containing waste and to relocate that…

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Design-Build: I-91 Twin Bridges over Williams River in Rockingham, Vermont

Large Bridge I-91 Northstar Hydro is part of the Design-Build Team of Reed and Reed and HDR for the replacement of the twin bridges that carry I-91 over the Williams River in Rockingham, Vermont. NHI provided hydrologic, hydraulic, and scour analysis Northbound and Southbound (NB and SB) bridges Work completed included hydrologic analysis, hydraulic modeling, and scour analysis based on site specific channel survey and FEMA data. A geomorphic assessment of the river and project reach were also prepared. Project components included consideration of FEMA elevation and floodway data, existing and proposed condition models, ice jam considerations, and scour and geomorphic assessments.…

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Androscoggin River Bridge Replacement in Durham and Lisbon

The existing Route 9/125 Bridge over the Androscoggin River at Durham/Lisbon Falls was recently replaced. The bridge is located approximately 1200’ downstream of the Worumbo Dam and spans the narrowest segment of the river. The bridge is founded on rock at both abutments and at the piers on rock islands. A channel that carries flow from the dam tailrace is located below the eastern opening between the abutment and the first pier. The bridge has two piers and two abutments. Northstar provided hydrologic, hydraulic and scour evaluations associated with the design of a replacement bridge with the final alignment residing upstream of…

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Design Build: I-91 Twin Bridges over West River, Brattleboro, VT

Aesthetic Design-Build Bridge over Famous Kayaking River Subcontractor for hydrologic, hydraulic and scour design services for design-build replacement of I-91 bridges over West River in Brattleboro, Vermont. Design included evaluation of complex pier scour, potential ice effects, and potential for rock scour for major highway bridge over medium sized river. Subcontractor to FIGG Bridge within Design-Build team