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vhb Design Services & Project Management of Downtown Riverfrant implementation
October 31, 2019
1.4.14 - Concept Design for Trail
This sub area includes the conceptual design of a future trail that will connect westerly
toward the broad Street Parkway and possibly beyond. The design will also account for a
potential future multi-use bridge connection across the river, including planning for likely
structure support locations. This area will require close coordination with the land owner to
determine how the trail would integrate into their development plans.
Product: Provide up to two (2) design alternatives including plans, typical cross sections, and
sketches as appropriate to define the proposed improvements.
Lead Consultant: VHB
Support from: Halvorson, HSI
1.5 River Hydrology
Any of the design that would result in fill within the floodplain and floodway must be
coordinated with HL Turner since they will maintain the river hydraulics model.
HL Turner will develop 2-, 5-, 10-, 50-, 100- and 500- year peak Nashua River flows using
data/analysis of stream flow records from the USGS’ Pepperell, MA gage, transposed downriver
to the project site.
HL Turner will create a project design river hydraulic model using the current effective FEMA
HEC-RAS model, and determine flow-water surface elevation profiles for the 2-through 500-year
peak river flows, and the FEMA regulatory floodway zone.
Based on the agreed upon project design flood resiliency and structural criteria, HL Turner will
select and insert the design Concept Plan features into the project design hydraulic river model.
HL Turner will provide VHB and the Project Team the results of the hydraulic impacts (i.e. water
surface elevation rises, floodway impacts and river velocity increases) identifying impacts and
recommendations on how to deal with the impacts (i.e. removai or reorientation of certain plan
features).
Lead Consultant: HL Turner
Support from: VHB, Halvoson
Estimated Duration: 10 weeks
1.6 Lighting
It is understood that the majority of the conceptual Riverfront lighting design has already been
advanced under an existing City contract by Lumen Design Studios with support from
Fitzemeyer & Tocci for power supply. There may still be a need to involve these team members
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