Indiana Stabilized Construction Site Access BMP Detail
The surface waters of Indiana are a cornerstone of the state's environmental and economic footprint, literally shaping the state and forming natural borders. The freshwater shores of Lake Michigan in the northwest region of Indiana and the confluence of the Wabash and Ohio Rivers create the unique shape at the southern end of the state. The state is also home to an estimated 24,000 miles of flowing water, including the Wabash River, which includes the longest stretch of free-flowing river east of the Mississippi (about 411 miles). The rich history of the Wabash River is a treasure in the narrative of Indiana's past.
The quality of these water sources is pivotal to the health of the ecosystem, agriculture, and economy. These waters support agriculture, industry, recreation, and drinking water supplies across Indiana. These waters also supply drinking water for the state and therefore directly affect public health if their quality declines. The protection of stormwater discharge systems is of critical importance to maintaining water quality throughout the state. Citizens, businesses, and governments work together to support a pure and protected habitat for life in Indiana.
Indiana NPDES Stormwater Permits
The Clean Water Act established the National Pollutant Discharge Elimination System (NPDES) permit program to set limits on sediment and pollutant discharges into surface waters nationwide. In Indiana, this program is administered by the Office of Water Quality (OWQ) within the Department of Environmental Management (IDEM). The construction stormwater program requires permit coverage for construction activity disturbing one (1) acre or more, including smaller sites that are part of a larger common plan of development or sale.
Most construction projects in Indiana obtain coverage under IDEM's Construction Stormwater General Permit (CSGP). Projects must obtain coverage before land-disturbing activities begin by submitting a Notice of Intent (NOI) and providing a Construction Plan that includes a Stormwater Pollution Prevention Plan (SWP3). Instead of a permit application, operators are required to submit a Notice of Intent describing the scope of the project and a Construction Plan, also called a Storm Water pollution prevention plan (SWP3).
The NOI informs IDEM of the planned scope of work, while the Construction Plan identifies the primary sources of pollution expected from the construction activity. The Construction Plan includes the SWP3 for both the construction and post-construction phases and must meet CSGP requirements (and, where applicable, local MS4 requirements). The Construction Plan also describes in detail the practices to be implemented to mitigate pollution at the construction site, known as Best Management Practices (BMPs). The operator or site engineer will be responsible for developing a plan and selecting BMPs to prevent pollutants from leaving the site and entering the stormwater drainage system or spreading onto surrounding roadways.
The Department of Environmental Management (IDEM) creates a stormwater manual to aid engineers in developing the SWP3/Construction Plan.
Stabilized Construction Site Access BMP
A Stabilized Construction Access or Construction Entrance is one of the first BMPs listed in the IDEM stormwater manual for the construction schedule.
The purpose of installing construction access protection measures is to minimize the potential for soil to be tracked onto public or private roadways by vehicles exiting an active construction site.
Chapter 5: Indiana Storm Water Quality Manual
Without this measure, rain events can wash sediment-laden water into storm drains, which can then enter surface waters and lakes, degrading water quality and harming aquatic ecosystems.
An efficient and properly installed entrance must protect all access points into the construction zone. A Stabilized Construction Entrance serves both to prevent soil tracking and to create a safe, stable environment for the heavy traffic entering and exiting the construction zone. The entrance must be inspected regularly and maintained to remain stable and effective as traffic and weather conditions change.
Stone Pad Stabilized Construction Entrance
A gravel construction entrance option is a traditional method for sediment tracking prevention on construction sites. The Indiana Storm Water Field Guide issued by the Indiana Department of Transportation (IDOT) includes examples of stormwater BMPs, including the stone pad style Construction Entrance, along with specifications for use on IDOT projects. The specifications require an aggregate pad to be a minimum of 12' wide and 50' long. It is best practice to extend the length of the entrance to 150'. The aggregate uses rough stones to clean sediment from vehicle tires effectively, and the guide recommends #2 stone. The aggregate should be large enough to prevent rocks from becoming wedged between dual-tire trucks or larger equipment that may use the entrance. In addition, a geotextile fabric is placed under the gravel vehicle tracking pad to protect the native soil from any sediment pollution removed by the aggregate.
As the project continues, the aggregate will become compacted and saturated with sediment. Daily monitoring and regular maintenance will be required for the operator to restore the performance of the construction entrance. Maintenance includes redressing the gravel pad with additional aggregate or repairing areas where the filter fabric has been damaged.
In addition to constructing and maintaining the Construction Entrance, the operator is required to sweep the roadway as needed to remove any fugitive debris, rocks, and sediment tracked onto it.
On projects where the stone entrance is insufficient to minimize sediment tracking, operators may opt for more aggressive, practical techniques to clean vehicle tires, such as wheel-wash systems, wet pits, wash rack stations, or mechanical cleaning methods. When using water to clean vehicle tires, operators must contain contaminated tire runoff using a sediment trap or sediment basin to prevent it from entering storm drains. Other requirements, such as power, may also be required to install a tire wash station.
FODS Vehicle Trackout Control Mats
A modern BMP for minimizing vehicle sediment tracking is the FODS Trackout Control System. The system consists of a single layer of HDPE matting, which is formed into pyramid-shaped structures across the surface. The pyramids deform vehicle tires and open treads, allowing trapped debris to break loose. The debris is collected at the base of the pyramids, where it is periodically swept away using a shovel or power broom.
The FODS Trackout Control Mats are designed for high-use applications and have been demonstrated to reduce required street sweeping by 59% compared to traditional gravel pads. The 12 panels are 7 feet long and are designed to be installed in series to construct a single lane for exiting traffic. The system can be installed to accommodate expected traffic and reconfigured during each phase of the project or across multiple projects throughout the product's 10+ service life.
As a reusable, portable system, the FODS Construction Entrance BMP enables contractors to construct an effective entrance on every project easily. Since no water or aggregate is required, the system can be deployed in nearly any environment. When the project is finished, the mats can be transported to the following site using a standard utility trailer while the entrance begins final stabilization. Contractors using this modern BMP can maintain compliance and reduce costs on every project.
Additional Resources:
Indiana National Pollutant Discharge Elimination System (NPDES) Program
IDEM Stormwater Quality Manual