Delaware

Delaware Stabilized Construction Entrance BMP

There are 27 major rivers and creeks that run through the state of Delaware. Additionally Delaware’s minor stream system consists of 437 smaller waterways that connect the stormwater from across the state. The largest of Delaware’s rivers is also the namesake of the state: the Delaware River. The Delaware River drains a total of 13,500 square miles of land in Delaware, New Jersey, New York and Pennsylvania. This watershed is mostly forested land, yet the waters in its bank provide drinking supply to 17 million people. The Delaware River’s rich history includes transportation of wine, aiding in developing industries, and strategic efforts during the American Revolutionary War.

Economically, Delaware became a hub for manufacturing and industrial growth after World War II. As regulations developed, industrial sites and construction managers work to bring the best practices to the state to protect the water quality and local ecosystems. Residents, businesses, operators, and the government alike work together to set standards and guidelines for water purity protection.

Delaware Department of Natural Resources and Environmental Control (DNREC) NPDES Permits

The Clean Water Act (CWA) of 1972 sparked laws and guidelines for industries and construction projects to mitigate pollutants introduced into the watershed system. The Act resulted in the creation of the National Pollutant Discharge Elimination System (NPDES) Permit Program which regulates all discharges into the nation’s surface waters. This permit program requires industries and construction operators to minimize sedimentation and contaminant levels to safe limits established by the state.

In the state of Delaware, the Department of Natural Resources and Environmental Control (DNREC) administers the NPDES Permit Program. Operators of industrial, municipal and construction sites must obtain permit coverage before beginning activities. Any construction sites that disturb an area of one acre or more must obtain NPDES stormwater permit coverage coverage. Many construction projects can obtain coverage through the Construction General Permit (CGP) by submitting a Notice of Intent (NOI) along with a site planning documentation including a Storm Water Pollution Prevention Plan (SWPPP).

A SWPPP is a document that specifies all potential sources of pollution on the job site and indicates which techniques or measures will be taken to contain the pollutants on site. These measures are called Best Management Practices or BMPs, and in many cases BMPs are used in combinations to address a single pollution source.

The DNREC creates the Delaware Erosion and Sediment Control Handbook to assist the SWPPP planning and development process for contractors and engineers. In this handbook are common devices and methods used to prevent the site from negatively affecting the storm water including soil testing, dust control, mulching, and stabilized construction entrances. 

Stabilized Construction Entrance (SCE) BMP Details

A construction entrance is usually one of the first practices implemented by an operator prior to other construction activities. Construction entrances stabilize the heavily trafficked ingress/egress points and are designed to minimize off-site tracking from vehicles and equipment that is exiting the site onto public road ways. This BMP is installed at every access point on the site to ensure each sediment source is minimized and contained.

The construction entrance (SCE) BMP is used in conjunction with other BMPs such as daily street sweeping and sediment basins to capture runoff. Street sweeping or scraping is conducted on a regular basis and after every rain event to ensure sediment and debris is captured before entering storm drains.

There are several options for designing and building an effective construction and each has its own maintenance routine that must be observed.

Aggregate Stabilized Pad Construction Entrance

Image of aggregate based stabilized construction entrance (SCE) from Delaware ESC Handbook.

Diagram of aggregate based stabilized construction entrance (SCE) from Delaware ESC Handbook.

The Delaware Erosion and Sediment Control Handbook includes an example of an aggregate based construction entrance which consists of a gravel tracking pad underlaid with a geotextile fabric. The gravel pad is installed at a mime depth of 6” and using DE #3 crushed stone. Aggregate entrance dimensions are a minimum of 50’ in length and 10’ in width. Additionally, a flare must be incorporated where the construction entrance meets the public roadway to accommodate the turn radius of the vehicles.

The rough surface created by the crushed stone acts on vehicle tires to capture sediment and debris. Rocks should be sized to the largest vehicles on site to prevent traffic hazards. Small rocks may be tracked onto the active roadways, or become lodged between dual tire vehicles and expelled at high speeds.

The entrance should be monitored daily as the gravel will become compacted and saturated with sediment and debris. When the surface is no longer rough, operators must install an additional aggregate to ensure adequate performance.

If the aggregate entrance is ineffective at removing sediment from vehicle tires, the length of the construction entrance may need to be extended or additional BMPs may need to be installed to supplement the aggregate tracking pad. A wheel wash can be added to a gravel entrance to remove any pollutants that still cling to the vehicle.


Wheel Wash

Diagram of wash rack, or wheel wash station, style construction entrance (SCE) from Delaware ESC Handbook.

When a stone stabilized construction entrance is not sufficient to contain the tracking of sediment onto the roadway, a wheel wash is often used. Wheel washes can be used as a stand alone BMP or as a supplement to an aggregate construction entrance. A wheel wash, wash rack, or tire wash station is a area where a vehicle can receive additional cleaning from pressurized water to clean vehicle tires. Wheel wash stations will require a source of power and water to operate. The wheel wash requires a water supply and the installation of a sediment basin to collect, filter, and appropriately discharge the used water.

FODS Trackout Control System

The pyramids on the surface of the FODS Stabilized Construction Entrance BMP works to deform vehicle tires and break trapped debris loose.

The FODS Stabilized Construction Entrance System is a modular, reusable BMP designed to minimize construction site track out. The system is comprised of durable 12’ wide by 7’ long matting which is formed into pyramids. The pyramids create a rough surface which causes tire treads to spread open and release trapped debris.

Compared to traditional techniques, FODS offers a number of benefits to site operators. The FODS system does not degrade or become compacted over time and is up to 59% more effective than aggregate based systems. FODS can be installed over any substrate and does not require any power or water source to operate. Because the system does not use rock, the risk of rocks entering the roadways or being expelled from dual tire vehicles.

Because the system is more effective than rock, the mats are well suited for compact work environments. A 1x5T mat configuration (35’ long) is commonly used to replace 70’ rock entrance while providing a wide turning radius for exiting traffic. The mats provide a 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.

The system is easily deployed in as little as 30 minutes which allows contractors to relocate and reuse the system as needed on each project. The mats are designed to be reused on multiple projects throughout their 10+ year lifespan.

 

Submittal Package

Install Guide, Drawings and Specs.