Project Steps
Each stage will consist of the following steps:
Survey
The project would begin with bathymetric survey of the channel. The purpose of the bathymetric
survey is to obtain existing channel geometry and elevation information. The survey information collected will be used to complete hydraulic modeling of the
Otter Tail River and evaluate the impacts of the proposed channel improvements on channel
hydraulics and water levels. The survey information will also be used to estimate excavation
quantities associated with the potential channel improvements.
The bathymetric
survey methods will generally be completed in areas with 18 inches or more of water depth. Areas
that need to be surveyed but are too shallow will be supplemented with terrestrial GPS survey.
Preliminary Design
Once the survey is completed, we will begin design work and begin assembling a preliminary
design set of plans. Historic lake levels as well as historic dredging permitting/plans will be used to
inform the design of the channel improvements. Past permitting allowed for a 30-foot channel with
4 feet of depth. Historic water levels on Otter Tail Lake and Otter Tail River modeling will be used
to inform the channel improvement geometry and elevations.
Hydraulic modeling of the river system will be completed to determine the effects of the channel
improvements on flow through the canals as well as effects on the Otter Tail River throughout the
reach. The hydraulic modeling will inform the design and will be required by the MN DNR during
the permitting process.
Permitting
Permitting that is anticipated right now
includes: US Army Corps of Engineers – Section 404 permit, MN DNR Public Waters Work Permit,
and a construction stormwater permit through the MN Pollution Control Agency. Depending on how
this project is ultimately perceived by permitting agencies, an Environmental Assessment
Worksheet (EAW) is often required for projects of this nature. The EAW process takes
approximately 5 months to complete. The environmental rules category which would apply is MN
Rules 4410.4300, Subpart 27 Wetlands and Public Waters. Based on that rule, a mandatory EAW
is required for “projects that will change or diminish the course, current, or cross-section of one acre
or more of any public water or public waters wetland except for those to be drained without a permit
pursuant to Minnesota Statutes, chapter 103G.” Wetland delineations are not anticipated in the
channel areas, but may be required in areas where excavated material is placed. If placement of fill
is within the Otter Tail County shore impact zone, then a permit will be required from Otter Tail
County Land and Resource.
Final Design & Preconstruction
In Phase 3 of the project, we would assemble the bid construction plans (often there are changes
that are made due to permitting conditions) and specifications once we have received the
necessary permits for the project. We would make public the bid documents to contractors and
answer any reasonable questions bidders might have about the plans and specifications. We
typically would oversee the bid opening and facilitate the contract agreement between the selected
contractor and the OTRM..
Construction
We would administer the construction contract and coordinate a pre-construction meeting with the
contractor and OTRM representatives. We would provide construction staking as necessary for the project. We typically observe the construction of the project to ensure conformance of the
construction with the design.
After closeout of the construction contract, we would assemble record drawings for the project that
incorporate any changes that occurred during the construction of the project and provide a hard
copy and electronic copy to the OTRM as well as the permitting agencies requiring them as permit
conditions.