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Williston, ND Airport Ditch Repairs


Williston, North Dakota

About the Project

An extreme rainfall event on June 11, 2021, resulted in damage to drainage infrastructure, including the Airport Ditch, which is a drainage channel that extends approximately 7,200 feet through the City.

A 1,000-foot section of the channel, with a contributing watershed area of approximately 3,227 acres, experienced significant damage to existing channel armoring which was composed of gabions, articulated concrete block, and riprap.

In addition to failure of channel armoring, significant erosion and head cutting occurred in the upstream segment of the damaged channel, which exposed utilities and led to a region of sediment deposition downstream.

Project Details

Date: 2021 – 2022

Client: City of Williston

Key Project Elements
  • Failure of Existing Stabilization Erosion
  • Fast-tracked Project
  • NEPA/USACE Permitting
  • H&H Modeling
  • Limited Construction Corridor
  • Constant Baseflow and High Groundwater
  • FEMA Grant Funding
  • Easement Review and Staking

The City selected AE2S to assist in review of the Airport Ditch and design of repair alternatives for the damaged section of the channel. The initial phase of the project consisted of review of the existing infrastructure and damaged channel to identify potential failure mechanisms that could be addressed as part of the repair project to avoid a similar failure in the future.

AE2S also developed a 1D/2D Infoworks ICM model to help quantify design flows and velocities that were likely experienced in the channel during the flood event. The model helped validate the flood conditions and damage that occurred and was used to inform the development of improvement alternatives.

Once AE2S understood the site hydraulics and potential failure mechanisms, repair alternatives were developed and reviewed with the City. Although more natural restoration options were considered, due to the intensity of flows, proximity to homes, and client preference, a riprap heavy approach was chosen.

Once an approach was selected, preliminary and final designs were developed by the AE2S team that included site specific design features to improve the resiliency of the channel, accommodate maintenance needs, and address site-specific limitations. AE2S prepared final plans and specifications for the project and provided bidding services to the City. The City also retained AE2S for assistance with construction services during the summer of 2022.

In addition to study, design, and bidding services, the AE2S team provided permitting and grant funding services to the City for the project, including FEMA grant funds and a Nationwide Permit from the U.S. Army Corps of Engineers.

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Williston Airport Ditch Repair