Texas Stabilized Construction Exit
In 1998, Texas assumed the administration of the National Pollutant Discharge Elimination System. The Texas Commission on Environmental Quality (TCEQ) administers the EPA requirements under the Clean Water Act and implemented the Texas Pollution Discharge Elimination System (TPDES) program. This program oversees stormwater discharges into Texas surface waters with the exception of discharges associated with oil, gas, and geothermal exploration and development activities, which are regulated by the Railroad Commission of Texas.
Texas TPDES Construction General Permit TXR150000
The TPDES Construction General Permit, or TXR150000, authorizes the discharge of stormwater from construction sites while ensuring correct measures are taken to comply with TPDES regulations. Construction projects that disturb an area greater than 5 acres are always required to obtain a permit and submit a Storm Water Pollution Prevention Plan (SWPPP or SWP3). Texas Storm Water permits which are issued for construction sites between 1 and 5 acres and are not part of a larger construction project can potentially obtain a Low Rainfall Erosivity Waiver.
To obtain a permit, an application must be submitted with a Storm Water Pollution Prevention Plan (SWP3). A SWP3 identifies potential pollution sources and also serves as a road map pollution prevention measures that will be implemented on the project. Individual SWP3s can be implemented by operators, or one SWP3 that covers the entire project can be shared between operators. Shared SWP3s must include the signature of each operator and clearly outline each of their respective responsibilities. Operators must also coordinate to ensure that any changes to plans or BMPs do not reduce the effectiveness of pollution and erosion controls implemented by other operators. One component of the SWP3 outlined in the Construction General Permit is minimizing “off-site vehicle tracking of sediments and the generation of dust. The SWP3 shall include a description of controls utilized to accomplish this requirement.”
TxDOT STABILIZED CONSTRUCTION EXIT
Texas Department of Transportation (TxDOT) has implemented a statewide Storm Water Management Plan (SWMP) which includes Minimum Control Measures (MCMs) to keep in compliance with TPDES. The MCM for sediment trackout provides two types of stabilized construction exits which must include a graded substrate to direct drainage to a sediment basin. Type 1 exits consist of a traditional rock entrance with a depth of at least 8” of bull rock or crushed aggregate, while Type 2 exits are made of railroad ties and timbers. These stabilized exits must be redressed with additional rock as sediment builds in the aggregate and be removed after completion of the job.
TxDOT Alternative Construction Entrance BMP: FODS Reusable Construction Exit
FODS Trackout Control System is a rockless and waterless alternative to the TxDOT construction entrance. FODS has been demonstrated to remove over twice as much sediment from vehicle tires compared to traditional rock entrances. This modern construction entrance can be used on excavation, grading, and heavy civil projects where heavy traffic volume causes traditional systems to quickly degrade. Mats can be cleaned on-site to fully restore effectiveness which can minimize downtime and increase compliance with the TPDES permit requirements. A 1x5T layout is typically used to provide one lane of travel with a wide turning radius adjacent to the roadway. The FODS rockless stabilized construction entrance is a novel and effective way to control sediment trackout.
Texas Projects Using FODS Construction Entrance
In Harris County, major expansion projects are being conducted to increase the maximum water capacity of bayous, lakes and rivers to protect against flooding during extreme weather conditions. The Harris County Flood Control District conducted a comparison between the traditional rock construction entrance and FODS trackout control mats. The project was a large excavation site that had up to 800 trucks exiting the site per day. The report concluded that “FODS provided equal or greater performance than SCA” and the daily reports showed that roadway cleaning was reduced by 59%. This report provides a demonstration of the effectiveness of FODS mats in both wet and dry conditions.
FODS were used during the construction of a new campus being built just north of Austin which is expected to provide up to 15,000 new jobs to the Silicon Hills.
In Baytown just east of Houston, a $2 billion chemical plant expansion project in the Oil & Gas industry is using FODS to provide clean, long term trackout control.
FODS mats provide an effective alternative to traditional stabilized construction exits. The FODS Trackout Control System is modular and consists of a single layer of pre-manufactured mats that have pyramidal structures throughout the surface. This modular system can be installed in both single-lane or dual-lane layouts. As vehicle tires pass over the pyramids, the tire lugs expand allowing trapped sediment to fall to the base of the mat. Even after heavy use, mats can be fully restored by cleaning with a street sweeper or shovel. With an expected lifespan of over 10 years, FODS trackout control system lowers costs while increasing compliance.
Additional Resources:
Texas Pollutant Discharge Elimination System (TPDES) Program
TPDES TXR150000 Construction General Permit
DOT Stormwater Field Inspector Guide
TxDOT Standards - Item 506: Temporary Erosion, Sedimentation, and Environmental Controls