City Commission to consider $140,795 contract for storm water management plan

The City Commission will consider a $140,795 agreement with Water and Environmental Technologies for the Vinyard Road Storm Water Management Area Master Plan.

Development has continued along the northern edge of the city, creating the need for a regional storm water management facility to control and treat storm runoff before draining to Watson Coulee.

The master plan will provide a blue print for a regional storm water management facility to serve long-term development in the area, as well as address the immediate storm water management needs of the current and future phases of the Thaniel and West Ridge additions, according to Public Works.

Recent development in the area includes Eagles Crossing, Northview, Stone Meadows, Thaniel and West Ridge subdivisions.

The current phases of Thaniel and West Ridge were required to provide temporary storm water management facilities to reduce impacts to downstream private property.

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The Thaniel and West Ridge developers secured 40 acres of land adjacent to those developments for storm water management and a portion of the property will also serve as right-of-way for a storm drain trunk main and 43rd Avenue N.E./N.W.

The land is located east of the intersection of Vinyard Road and 6th Street N.W. The city has made arrangements with the developers to eventually transfer ownership of the land and storm water management area to the city.

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WET has indicated they have the available resources to perform the engineering work scope and complete the master plan by September 2018.

According to Public Works, reasons to provide proper storm water management in the area include:

  • the downstream area between 6th Street N.W. and Vaughn Road is drained by natural and manmade channels which are relatively flat, narrow and slow draining. These channels have limited capacity to handle increased peak flows;
  • between Vaughn Road and the Sun River, the drainage is routed into a large detention pond and then through twin box culverts to the river. These facilities were designed and constructed by the U.S. Army Corps of Engineers for flood control in west Great Falls. The design capacity did not assume significant upstream urbanization;
  • the West Great Falls Flood Control and Drainage District has expressed concern regarding storm water runoff into the basin; and
  • U.S. Clean Water Act regulations require storm water runoff from urban areas to be treated before discharging to water bodies such as the Sun and Missouri rivers. The city is permitted for these discharges.

The agreement covers basic engineering services include topographic and utility surveys; wetland delineation; geotechnical investigation; storm water hydrological and hydraulic modeling; design engineering for the storm water management area including ponds, wetlands and conveyance facilities; design engineering for the trunk storm drains and 43rd Avenue N.E./N.W.; cost estimates and funding splits; and construction phasing and scheduling, according to the staff report.

According to Public Works, WET has been selected on a rotational basis to provide the professional services in accordance with the city’s architect, engineer and surveyor selection policy and also based on WET staff’s familiarity with the work scope and their ability to perform the work in an acceptable time frame.

WET recently completed a master plan for the former smelter site in an agreement with Cascade County.

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The city is splitting costs for the project with the Thaniel and West Ridge developers who are responsible for proportional shares of the engineering costs associated with improvements serving each development master plan area.

City storm drainage and street funding will cover the professional services fees and the city will be reimbursed by West Ridge and Thaniel developers for their portion of the fees.