Vermont Stabilized Construction Access BMP

Vermont is the only landlocked state in the New England region, yet two important bodies of water encompass Vermont. Lake Champlain in the northwest region of the state is the sixth-largest body of fresh water in America and separates Vermont from New York State. This section of the state has been named the Champlain Valley and is known for its fertile land that provides the landscape for the state’s agricultural production. The Champlain Valley is part of the Saint Lawrence River drainage system which is the primary drainage basin of the Great Lakes into the Gulf of Saint Lawrence in Canada one of the largest estuaries in the world. The Connecticut River creates the natural eastern border of Vermont. Over 40% of Vermonts’s stormwater drainage empties into the Connecticut River which discharges into the Long Island Sound.

The Vermont Clean Water Initiative has reported that $194 million has been spent to begin restoring the purity of water throughout the state. This initiative continues to work to maintain the health of the water, ecology, environment, cities, and economy of Vermont.

Vermont Department of Environmental Conservation (DEC) NPDES Stormwater Permits

To mitigate effects of industrial and construction activities on the nation’s surface water sources the federal government initiated the Clean Water Act which established the National Pollutant Discharge Elimination System (NPDES) Permit Program. The Program establishes regulations on water discharges from municipal, industrial, and construction activities which could otherwise cause excessive sedimentation or pollution.

The Vermont Department of Environmental Conservation (DEC) administers the NPDES Permit Program which includes reviewing applications, issuing permits, and enforcing permit requirements. All operators of construction sites which disturb an area of one acre or more are required to obtain permit coverage. Most construction sites can obtain permit coverage under the Construction General Permit (CGP) 3-9020 by submitting a Notice of Intent (NOI) along with a Erosion Prevention and Sediment Control (EPSC) Plan.

Development of a EPSC Plan includes defining areas of disturbance and all potential pollution sources. The most common type of water pollution is sedimentation which occurs when excessive soil is deposited into the streams and lakes. The EPSC Plan will outline the strategies and techniques that will be used on site to mitigate erosion and to control pollutants from escaping the construction area. These strategies which can be either structural or procedural are called Best Management Practices or BMPs. A few of the effective measures that are necessary for a proper EPSC Plan are silt fences, sediment basins, rolled erosion control products (RECP), and Stabilized Construction Access.

Stabilized Construction Access BMP

Site entrances and exits receive high volumes of vehicle traffic which can track sediment onto the roadways which can wash into storm drains. To prevent this sedimentation a Stabilized Construction Access is installed to remove mud and sediment from vehicle tires before they exit the job site. A Stabilized Construction Access is usually one of the first practices implemented by an operator prior to other construction activities.

An construction access stabilizes the access points and removes the majority of sediment from vehicle tires. The construction entrance must be properly maintained to remain effective. Depending on expected traffic volume, multiple or alternative BMPs may be used to stabilize the entrance. In addition to stabilizing entrances, operators use street sweeping, vacuuming to recapture sediment that is tracked out of the job site.

Stabilized Rock Construction Exit BMP

The Vermont Standards and Specifications for Erosion Prevention and Sediment Control includes details of an aggregate stabilized pad which is commonly used to stabilized construction site entrances. Aggregate construction entrances consist of a 8” deep pad of 1”-4” stone or recycled concrete. The stone is laid over a filter cloth to keep the aggregate from sinking into the soil. Dimensions for the pad can vary depending on vehicles which will use the exit. The Standards list a 50’ minimum length and 12’ minimum length.

The standards include considerations to ensure the entrance is adequately preventing track out. In some cases, an aggregate pad may not be sufficient to remove the majority of the sediment. In these cases supplemental or alternative BMPs may be used to remove mud from vehicle tires.

Wheel Wash Station BMp

The Standards mention a wheel wash station which can be installed when additional cleaning is required. A wheel wash station consists of wash rack which is laid over a raised structure or a bed of gravel. Tires are washed either manually or using an automated system while vehicles are over the wash rack. When using a wash rack, all drainage must be intercepted and drained into a sediment trap or basin to prevent runoff from flowing off-site.

FODS Trackout Control System

The FODS Trackout Control System is an effective system for containing site trackout which uses mechanical action on vehicle tires to remove debris. The modular system consist of a series of 12’ x 7’ HDPE matting which is formed into pyramid shaped structures on the surface. The pyramids deform and flex vehicle tires in multiple directions to dislodge sediment, rocks, and debris which is lodged between tire treads. FODS can be installed over existing substrates including dirt, concrete and asphalt.

The FODS Construction Entrance Mats are designed to be reused on multiple projects over the 10+ year expected service life. The mats can be easily relocated which significantly reduces costs on phased projects and over the course of multiple projects. Installation, maintenance, and removal can be completed without the heavy equipment and a standard installation can be completed in under 30 minutes.

The 3” tall pyramids can hold up to 2.5” of sediment as the tires only come into contact with the tips of the pyramids. When maintenance is required, the street sweeper or a skid steer with broom attachment can be used to brush away sediment to restore performance. Manual cleaning can be completed with a FODS Shovel which is designed to fit between rows of pyramids. Contractors can integrate maintenance during regular street sweeping to ensure the entrance is always compliant with permit requirements.

The FODS system is more effective than traditional Rock Construction exits and has been shown to reduce street sweeping by 59% in high traffic volume applications. Because the system is highly effective, FODS are commonly specified at 50% of the length of a stone stabilized tracking pad to provide equal performance. Because no materials are consumed during the life of the project, FODS enables contractors to reduce costs on each project the mats are used.