Indiana Stabilized Construction Site Access BMP Detail
The surface waters of Indiana are a cornerstone in the state’s environmental and economic footprint and literally shape the state and form natural borders. The fresh water shores of Lake Michigan in the northwest region of Indiana, and the convergence of the Wabash River and Ohio River 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 is the longest free-flowing river east of the Mississippi. The rich history of the Wabash River is a treasure in the narrative of Indiana’s past.
The quality of these water sources are pivotal to the health of the ecosystem, agriculture, and economy. Over 80 percent of Indiana's land is used for agriculture or forestry, and these industries provide employment for over 180,000 residents of the state. These waters also supply the drinking water for the state and therefore directly affect public health if they fall in quality. The protection of stormwater discharge systems is of critical importance to maintaining water quality throughout the state. Citizens, businesses and governments work together to maintain 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 establish limits on sediment and pollutant discharge into surface waters across the country. In Indiana, this program is administered Office of Water Quality (OWQ) within the Department of Environmental Management (IDEM). The program requires all construction, municipal, and industrial activities to obtain a stormwater permit for any disturbance of ground equal to or greater than one acre.
Most construction projects in Indiana are able to receive permit coverage under the construction general permit, which is a permit by rule and is conditionally issued to all future projects who meet the requirements established by the rule. In lieu 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 about the planned scope of work, while the Construction Plan identifies the main sources of pollution that will be caused by the construction activity. The Construction Plan also describes in detail the practices that will be implemented in order to mitigate the pollution of the construction site which are called Best Management Practices or BMPs. The operator or site engineer will be responsible to organize a plan and select BMPs which will prevent the spreading of pollutants off of the site into the storm water drainage system or onto the surrounding roadways.
The Department of Environmental Management (IDEM) creates a stormwater manual designed to aid engineers in the development of the SWP3/Construction Plan.
Stabilized Construction Site Access BMP
A Stabilized Construction Access or Construction Entrance is one of the first BMPs on the construction schedule described in the IDEM stormwater manual.
The purpose of installing construction access protection measures is to minimize the potential of soil being tracked onto public or private roadways from vehicles as they exit 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 will enter the surface waters and lakes degrading water quality and causing damage to the aquatic ecosystem.
All access points into the construction zone must be protected by an efficient and properly installed entrance. A Stabilized Construction Entrance acts both to prevent soil tracking and to create a safe and stable environment for the heavy traffic that travels in and out of the construction zone. The entrance must be monitored daily and maintained as the stability and effectiveness degrades through normal use.
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. If possible it is the best practice to extend the length of the entrance to 150’. The aggregate use rough stones to effectively clean sediment from vehicle tires and the guide recommends #2 stone. The size of the aggregate should be large enough to prevent rocks from becoming wedged in between dual tires trucks or larger equipment which 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 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 also required to sweep the roadway as needed to remove any fugitive debris, rocks, and sediment which are tracked onto the roadway.
On projects where the stone entrance is not sufficient to minimize sediment tracking, operators may opt for a more aggressive, and effective techniques for cleaning vehicle tires such as a wheel wash system, wet pits, wash rack station, or mechanical cleaning methods. When using water to clean vehicle tires operators are required to contain the contaminated tire runoff using a sediment trap or sediment basin to prevent runoff 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 is composed of a single layer of HDPE matting which is formed into pyramid shaped structures throughout 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 to perform in high-use applications and have been demonstrated to reduce required street sweeping by 59% compared to traditional gravel pads. The 12’ panels are 7’ long and are designed to be installed in series to construct a single lane for exiting traffic. The system can be installed to accommodate the expected traffic and can be reconfigured during each phase of the project or on multiple projects throughout the 10+ service life of the product.
As a reusable and portable system, the FODS Construction Entrance BMP can enable contractors to easily construct an effective entrance on every project. 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 using a standard utility trailer to the next site 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