Retention Pond Remediation

Project Summary:

Project Type:
Stormwater Planning and Modeling

Owner:
ND Department of Transportation

Overview:

As growth from oil production impacted communities in western North Dakota, infrastructure improvements also grew. Located within the heart of oil country, Watford City has seen significant growth and its footprint expanded. New challenges faced the community, one of which was the drainage basin at the intersection of North Dakota Highway 1806 and North Dakota Highway 23.

The NDDOT realigned ND Highway 23 around the southeast side of Watford City in 2014. The realignment was constructed through a naturally existing closed basin. This meant the watershed did not have a natural gravity outlet. This created a retention pond. The runoff from the watershed would either pond until it infiltrated or evaporated. The city communicated concerns to the NDDOT of runoff remaining in the pond for a long period of time and potential of standing water impacting adjacent properties including a cemetery.

Project Details:

Apex collaborated with the NDDOT to resolve drainage issues and decrease the duration water stands in the retention pond. Two areas were studied: watershed and physical soils. Soils testing was performed by Terracon. Apex led the charge evaluating hydrologic parameters such as contributing area, land use, peak flows and volumes from typical rainfall events. With growth and changed layout of the land, there was increased runoff draining to the pond without an outlet. Several alternatives were studied including existing pond expansion, infiltration system improvements, gravity pipe outlet and pump station outlet. The NDDOT selected infiltration system improvements.

Preliminary design and soils investigation of the project began in the summer of 2017. Final design wrapped up in the winter of 2018 and the project was construction in the summer of 2018.

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