Illinois Stabilized Construction Entrance Detail
Bounded by the Mississippi River on its western border, Illinois boasts extensive, fertile farmland, earning the nickname "The Prairie State." Illinois is a leading U.S. exporting state, with a diversified economy spanning manufacturing, agriculture, transportation, and healthcare.
The iconic Cloud Gate in Millennium Park, Chicago, reflects the city's skyline, a major metropolitan center. The city is located on the shore of Lake Michigan, the second-largest of the Great Lakes by surface area. Illinois relies on water features that enable both crop production and manufacturing plant operations. The state manages water features through joint efforts among departments to share best practices and techniques.
IEPA Stormwater Construction Permits NPDES
The Illinois Environmental Protection Agency (IEPA) stormwater administration is authorized under the federal Clean Water Act. The IEPA issues stormwater permits under the National Pollutant Discharge Elimination System (NPDES) program. The program regulates all discharges to surface waters, including lakes and rivers.
Construction activities that disturb an area of 1 acre or more must obtain permit coverage under the NPDES program unless a waiver is granted. Municipalities and industrial operators must also obtain permit coverage for water discharges resulting from stormwater drains or industrial activity.
Operators of construction sites can request coverage under the NPDES Construction Stormwater Permit program by applying for an individual permit or, more commonly, by submitting an NOI to request coverage under the General Permit. In either case, the operator must develop, implement, and maintain a Stormwater Pollution Prevention Plan (SWPPP), which provides an overview of land-disturbing activities, potential pollution sources, and planned tactics to mitigate pollution. The tactics or techniques are called Best Management Practices and are compiled in the Illinois Urban Manual.
The Illinois Urban Manual (IUM)
The Illinois EPA funds the development of the Illinois Urban Manual, which is a technical reference developed and maintained cooperatively for developers, contractors, planners, and engineers. The Manual is vetted through the Urban Manual Technical Review and Steering Committees. It is cooperatively maintained through contributions from departments and organizations, including the Association of Illinois Soil & Water Conservation Districts (AISWCD), Soil & Water Conservation Districts (SWCDs), the Illinois Department of Transportation (IDOT), and the Illinois Department of Agriculture, Bureau of Land & Water Resources (IDA-BLWR).
Contained in the Illinois Urban Manual is a list of Best Management Practices (BMPs) and guidelines for their applications. The BMPs include information on bioretention facilities, diversion dikes, ditch checks, wetland creation, and Stabilized Construction Entrance details. Each of these BMPs is used to mitigate a specific source of pollution or sedimentation caused by soil-disturbing operations.
The Manual includes details for the practice standard of Stabilized Construction Entrance (No. Code 930). This is usually the first BMP to be installed on a job site and is constructed before land development begins. The purpose of a Stabilized Construction Entrance is to reduce or eliminate sediment tracking onto public right-of-ways or roads.
Illinois Stabilized Construction Entrance Detail
An essential BMP for any large construction site is the Stabilized Construction Entrance. This technique is traditionally composed of a stone entrance pad or a combination of a stone entrance pad with a wheel wash installed in series with the rock. The purpose of the stabilized entrance is to eliminate, reduce, or prevent off-site vehicular Tracking.
The Manual includes a description of this type of stone stabilized construction entrance consisting of a geotextile fabric (Class I, II, or IV) topped with 6" or more of IDOT coarse aggregate (CA-1 through CA-4). Typical guidance recommends a stone pad approximately 70 feet long and 14 feet wide, adjusted as needed for site conditions and vehicle traffic. Single-lot residential projects may reduce the minimum rock length from 70' to 30'. The site must be prepared to prevent runoff from the construction entrance from leaving the site, and measures must be taken to grade the area or divert the runoff to a sediment trap. Any sediment tracked onto roadways must be immediately removed to prevent it from washing down storm drains.
The stones agitate the sediment on the vehicle tires as they drive across. The sediment collects on the construction entrance and must be maintained by top dressing with additional aggregate. The entrance must be inspected regularly and after rain events to ensure sediment is sufficiently contained.
When a stone-stabilized construction entrance is not sufficient to contain sediment tracking onto the roadway, a wheel wash is often used. This involves creating a wash rack and a washing station to clean tires with pressurized water. Drained water must be contained and directed into a sediment basin, and must not leave the construction site.
IDOT Construction Manual
The Illinois Department of Transportation uses a SWPPP plan for all highway projects in the state. The IDOT Construction Manual references the standards in the Bureau of Design and Environment (BDE) Manual Chapter 41-3.06 for construction entrance guidelines. The BDE Manual, in turn, references the specifications in the IEPA Manual and adds a few details on the pay structure and recommendations for DOT projects.
The BDE Manual includes recommendations to limit the number of stabilized construction exits and to install wash stations in a two-lane configuration to avoid soil from incoming traffic depositing into the wheel wash, or to use a turn-out area for the same purpose.
FODS Reusable Stabilized Construction Entrance System
The FODS Stabilized Construction Entrance System is a practical, reusable solution for construction site track-out. The system comprises HDPE matting formed into pyramids that create a rough surface to deform tires. As construction vehicles pass over the mats, tire treads are spread open to release trapped debris. Mud and dirt collect at the base of the pyramids out of contact with subsequent vehicle tires. The system does not introduce aggregate to the job site and provides a safer solution than traditional methods, as there is reduced risk of aggregate Tracking onto an active roadway. After rain events, the mats can be quickly refreshed without requiring additional material.
Because the system is more effective than rock, the mats are well-suited for tight work environments. A 1x5T mat configuration is commonly used to replace a 70' rock entrance while providing a wide turning radius for exiting traffic. The mats offer significant savings to contractors as they can be reused for 10+ years, eliminating the cost of construction entrance materials. FODS can be installed in as little as 30 minutes and can be anchored to dirt or on concrete and asphalt in urban settings.
IDOT Tri-State Tollway I-294 Project
A common challenge in highway projects is working adjacent to active roadways; the recent developments on the I-294 tollway were no exception. The FODS Reusable Stabilized Construction Entrance System was used as a practical, portable stabilized entrance solution, allowing contractors to operate efficiently throughout each phase. The system does not require aggregate to be installed, thereby reducing the risk of rocks becoming lodged in dual-tire vehicles or being displaced onto roadways.
O'Hare International Airport
When working in conditions that require effective debris control, the FODS Construction Entrance provides an ideal solution. The $8.5B O'Hare Modernization Program involved major expansions, renovations, and operational changes to Chicago's International Airport. During the recent phase, Runway 9C-27C renovations involved demolition and recycling of 180,000 tons of pavement and the relocation of the Ground Runup Enclosure (GRE). The FODS Reusable Construction Entrance System was chosen to reduce FOD that escaped onto the runways and taxiways. The highly effective trackout control technique provided superior containment compared to traditional measures.
Additional Resources
IDOT Tri-State Tollway I-294 Project
Chicago O’Hare International Airport
Illinois Urban Manual - Practice Standards (Stabilized Construction Entrance - 930)