North Dakota Stabilized Construction Access BMP

The Great Plains of North Dakota make up the majority of the state's landscape and provide a sanctuary for both wildlife and residents. The Red River of the North forms the natural border between North Dakota and its neighboring state, Minnesota. This river collects the watersheds of the northeastern portion of the state, flowing into Lake Winnipeg and eventually emptying into the Hudson Bay. Two of the state's most populous cities, Fargo and Grand Forks, are both located on the banks of this river. The drainage basin of the South and West regions of North Dakota drains into the Missouri River, which flows into the Gulf of Mexico.

The rich soil provides abundant returns for farmers, which has led nearly every county in North Dakota to produce wheat, making it one of the state's chief crops. In addition, North Dakota leads the nation in canola production, contributing roughly 80-85% or more of U.S. canola output, and is also a top producer of flaxseed. The success of the agricultural economy in North Dakota is dependent on the purity of the water that naturally and artificially irrigates the crops. It is vital to protect this natural resource against pollutants and other activities that negatively affect the quality of the state's water. Together, residents, farmers, industries, and the government can collaborate to identify potential problems and mitigate their impact on North Dakota's stormwater system.

North Dakota Department of Environmental Quality NPDES Stormwater Permits

In 1972, the United States Congress enacted the Clean Water Act (CWA), which established regulations to reduce the impact of human development on the nation's surface waters. The Act created the National Pollutant Discharge Elimination System (NPDES) permit program. The North Dakota Department of Environmental Quality (DEQ) administers this program in the state under the North Dakota Pollutant Discharge Elimination System (NDPDES) permit, and is handled by the Department of Environmental Quality (DEQ).

Administration of the program includes reviewing applications, issuing permits, and enforcing compliance. The permit program requires construction and industrial site operators to obtain coverage before disturbing one or more acres of land, or smaller areas that are part of a larger common plan of development or sale that will ultimately disturb at least one acre. To obtain permit coverage, operators must submit a Notice of Intent (NOI) to the DEQ and develop and implement a Stormwater Pollution Prevention Plan (SWPPP), which is kept on-site and made available for review. The SWPPP outlines the methods and devices that will be used on-site to mitigate or eliminate the introduction of sediment, soil, and other pollutants into the public stormwater system. Creating an SWPPP first requires an operator or site engineer to identify all potential pollution sources that the construction activity will have on the surrounding land and stormwater system. The operator must then design methods and procedures to reduce or eliminate all sources of erosion and pollution. The measures and practices are referred to as Best Management Practices (BMPs), which can encompass both structural and procedural elements. Notable design features commonly implemented in an effective SWPPP include silt fences, soil retention blankets, seeding, and stabilized construction entrances.

Stabilized Construction Access Detail

The purpose of a Stabilized Construction Access BMP is to minimize sediment tracking from vehicle tires as they exit the job site. Site entrances must be stabilized before commencing land development and other construction activities; therefore, the Stabilized Vehicle Exit is typically one of the first to be installed. All access points on the site that exit onto public roads must have a stabilized construction entrance.

Stabilized Construction Site Exits will require ongoing inspection and maintenance to ensure that they remain in adequate condition. In addition to the Construction Entrance BMP, operators will regularly sweep streets to capture any sediment that is tracked onto the roadway before it can enter storm drains. This combination of BMPs can significantly decrease sedimentation.

Aggregate Style Stabilized Construction Access BMP

The North Dakota Department of Transportation's (NDDOT) Erosion and Sediment Control Manual (ESCM) describes an aggregate-style Stabilized Construction Site Exit, which is comprised of a tracking pad made from large aggregate, typically 50' to 100' in length. The length of the entrance should accommodate the largest vehicles that will be exiting the site, providing adequate tire rotations. A geotextile fabric is used to separate the aggregate from the natural soil below, and helps to prevent the aggregate from sinking into the soil. The size of the aggregate should be large enough to provide a rough surface and prevent stones from becoming stuck between dual tires.

Maintenance of an aggregate construction entrance is necessary when the rock becomes compacted due to heavy use or becomes saturated with sediment. To restore the aggregate pad, additional rock is used to top-dress the tracking pad, restoring the rough surface. Inspections should be conducted on a regular schedule, as well as after every rain event, which can cause excessive mud to be deposited on the rock.

When an aggregate Construction Exit is not adequate to contain the majority of tracked sediment, additional or alternative BMPs may need to be installed.

Storm effects, excessive traffic, and other factors may compromise the construction exit, leading to inefficient sediment and soil retention. In this case, the aggregate construction access must be supplemented by other control techniques. A common addition to any construction entrance is the wheel hose-down system.

Steel Tire Cleaning Device Construction Exit BMP

Steel rumble plates, also called shaker plates or rumble plates, are another option for reducing tracked sediment. This device is manufactured with angled steel to create a washboard effect, which shakes tires to remove debris. These systems are often used in conjunction with an aggregate-style entrance. Some rumble plate systems are installed over an excavated void to capture soil. Maintenance is required when mud and sediment build up in the voids between the angled steel rows. Heavy equipment may be necessary to reposition, move, or clean the steel plates.

Wheel Wash Station BMP

A wheel wash station uses either manually operated or automated pressure washers to spray vehicle tires, removing sediment. Wheel Wash Stations require a source of power and water to operate. In addition, the sediment-laden water must be diverted into a sediment basin to prevent runoff from entering the roadway.

FODS Trackout Control System

FODS Trackout Control System is a modern BMP designed to minimize sediment tracking on construction sites. The system consists of modular HDPE mats, which are formed into pyramid-shaped structures throughout the surface. The pyramids deform and flex vehicle tires in multiple directions to dislodge sediment, rocks, and debris that is lodged between tire treads. The voids between the pyramids capture sediment.

The FODS Construction Entrance Mats are durable and designed for reuse on multiple projects over their 10+ year expected service life. Construction Entrances can be easily relocated, which significantly reduces costs on phased projects and throughout various projects. Installation, maintenance, and removal can be completed without the heavy equipment. The system is versatile and can be configured as needed, then quickly redeployed on dirt, concrete, or asphalt in under 30 minutes.

The system does not degrade during heavy use or after rain events. The 3" tall pyramids can hold up to 2.5" of sediment, as the tires only come into contact with the tips of the pyramids. When maintenance is required, a pass with a street sweeper or a skid steer with a broom attachment is all that is needed to restore performance. Contractors can integrate maintenance during regular street sweeping to ensure the entrance is always compliant with permit requirements.

The modular FODS system outperforms traditional stone-stabilized construction entrances and is commonly specified at 50% of the length of a stone-stabilized tracking pad to provide equal performance. Additionally, the system is both flexible and cost-effective, allowing contractors to reduce sedimentation and costs on each project where the mats are used.