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.