Washington Stabilized Construction Entrance / Exit (C105)

The northwestern corner of the state of Washington borders the Pacific Ocean on the west and the Salish Sea on the north. The network of bays and canals extends inland towards the cities of Seattle and Olympia. The coastal climate provides plenteous rainfall which replenishes the rivers and lakes in the mountainous regions towards the east. These water features support a lively ecosystem including the salmon which make their annual return to their upstream spawning grounds. The National Pollution Discharge Elimination System (NPDES) regulates water quality and ensures that the residents and wildlife have access to clean water.

Washington NPDES Stormwater Permits

Washington’s Department of Ecology, administers the NPDES program. Operators request a stormwater permit under the NPDES program by submitting an application along with a Temporary Erosion and Sediment Control Plans (TESCP) or Stormwater Pollution Prevention Plan (SWPPP) which identifies potential pollution sources and specifies mitigation techniques that will be implemented to minimize pollution.

The department creates Stormwater manuals to assist operators as they develop SWPPPs and advises about Best Management Practices (BMPs) that can be used to minimize pollution. Manuals are created for both the western and eastern parts of the state and requirements will vary depending on where the site is located.

Construction operators who are conducting activities that disturb an area of one acre or greater are required to obtain a construction stormwater permit. Many construction operators can apply for coverage under the Construction Stormwater General Permit.

C105 Stabilized Construction Entrance / Exit

One of the first BMPs that is established on a site is the Stabilized Construction Access or Stabilized Construction Entrance/Exit. This BMP is designed to contain sediment and contaminants that would be tracked out on vehicle tires. The manual describes a traditional approach to establishing a Stabilized Construction Access which includes a geotextile fabric underneath a 12” thick layer of quarry spalls; crushed concrete, cement, or calcium chloride are not permitted because they will affect the stormwater pH level. The rock entrances are constructed 15’ wide and 100’ in length and must be established at each entrance/exit location. As larger sites progress through each phase, additional entrances may need to be established. The manual recommends that contractors prepare for additional entrances than were originally included in the TESCP (or SWPPP) because “it is difficult to determine exactly where access to these project will take place.”

As vehicles travel over the rock entrances, the rocks become compacted with soil and sediment. The entrances are maintained by adding more quarry spalls to the entrance or by increasing the length of the entrance. Any stone or sediment that is tracked onto the roadway must be immediately removed by sweeping or with a shovel. If sediment is not sufficiently contained within the site, additional must be added to the entrance or a wheel wash must be installed.

After construction is finished, the entrance must be permanently stabilized. Permanent stabilization requires removal of all temporary control measures including the quarry spalls and geotextile fabric, replacing topsoil, and reseeding grass or other natural features.

For more Washington State Approved C-105 entrances check out the Washington Storm Water: Construction BMP Guide.

C106 Wheel Wash

When rock construction entrances are not adequately preventing tracking, wheel wash stations can be installed. Wheel wash stations with pressure washers can effectively clean tires of vehicles when they are placed adjacent to paved roadways. The sediment laden water must be contained or diverted to a sediment basin within the site.

Some wheel wash systems are manufactured while others are built as concrete structures on the job site. The wheel wash systems provide an effective solution to trackout, but may pose challenges to contractors requiring more flexibility for the construction access locations.

FODS Reusable Construction Entrances

FODS Reusable Construction Entrance/Exit System is a durable and effective alternative to the traditional Stabilized Construction Access techniques. The system is comprised of HDPE mats which have a pattern of pyramid shapes on the top surface. The pyramids deform the tires of vehicles as they drive over the mats and dislodge soil and sediment trapped in the tire tread. Roadway tracking is reduced more effectively with FODS mats compared to traditional Stabilized Construction Entrances which can result in as much as 59% reduction in street sweeping.

FODS Mats can be relocated throughout the project allowing contractors to have more flexibility when planning their construction operations. In addition the system is designed be used on multiple projects throughout their 10+ year lifespan making them very cost effective for both contractors or industrial operators.

When sediment becomes compacted on the mats, they must be maintained to continue preventing trackout. The mats can be cleaned using a street sweeper with an adjustable head, a skid steer with broom attachment, or manually with a shovel. Because there is no rocks used in the system, remediation is often significantly reduced compared to traditional construction access techniques.

FODS Approved For Use By Washington Department of Ecology

The FODS Trackout Control System has been reviewed by the Washington Department of Ecology and has been approved for use throughout the state. Contractors in the state may benefit from the use of the FODS Construction Entrance without seeking any additional approval by the department.

The FODS System is an effective and environmentally responsible BMP which enables contractors to minimize sedimentation and stay compliant with NPDES requirements. Compared to traditional rock entrances the FODS system can reduce waste and transportation emissions and can be fully recyclables at the end of the product’s 10+ year service life.