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VO Design Services & Project Management of Downtown Riverfront Implementation
July 31, 2020
HL Turner has developed 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 utilize their project design river hydraulic model using the current effective
FEMA HEC-RAS model, and determine ‘low-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 plan features into the project design hydraulic river model.
HL Turner will provide VHB and the Project Team the results of the hydraulic impacts (Le.
water surface elevation rises, floodway impacts and river velocity increases) identifying
impacts and recommendations on how to deal with the impacts (i.e. removal or
reorientation of certain plan features, or creation of mitigation areas).
Lead Consultant HL Turner
Support from: VHB, Halvoson
2.3 Permitting
Permit applications will be prepared after Phase 2 when the impacts are well defined, but
during Phase 2 the design team will be cognizant of the potential permitting implications
of every aspect of the design when important design decisions are betng made. As the
design progresses VHB environmental specialists will advise the design team relative to
permitting implications. In addition, The HL Turner Group will provide crucial input on any
in-stream or shoreline work that couid potentially affect flood levels.
Lead Consultant: VHB
Support from: HL Turner
2.4 Utility Coordination
Utility coordination at this stage is assumed to be minimal since the designs and impacts
are preliminary. A small fee is included to cover correspondence and issuing plans to
potentially impacted utility companies.
Lead Consultant: VHB
2.5 Property Owner Coordination
Considering budgetary constraints and the coordination that has occurred during
conceptual design, a minimal fee is included for this task. It is assumed the City will
arrange any calls needed with affected property owners.
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