3.16 Wheel Cleaning Systems - City of Denton · Wheel Cleaning Systems CC-172 April 2010, Revised 9/2014 E-172 3.16.1 Primary Use Wheel cleaning systems are used to remove soil from

iSWMTM Technical Manual Construction Controls

Wheel Cleaning Systems CC-171 April 2010, Revised 9/2014

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3.16 Wheel Cleaning Systems

Sediment Control

Description: Wheel cleaning systems are

used with a stabilized construction exit to remove soil from vehicle wheels and undercarriages prior to leaving the construction site. The cleaning system may be as simple as uneven, steel racks that “rumble” the vehicle or as complex as a pre-manufactured wash bay. Systems that include wash water must provide for collecting the water and removing sediments and other pollutants prior to discharge.

KEY CONSIDERATIONS

DESIGN CRITERIA:

Locate within the stabilized construction exit

Design according to type of soil and the number and size of vehicles using the cleaning system

Provide a means of collecting wash water and removing sediment before discharge ADVANTAGES / BENEFITS:

Effectively reduces off-site sediment tracking

Components of the system may be re-used on different projects

DISADVANTAGES / LIMITATIONS:

Requires separate construction entrances and exits

Requires frequent cleaning to remain functional

Effectiveness dependent on operator training

Sediment trapping controls won’t remove oils or other pollutants in the wash water

Potential overflows and discharges of wash water if sediment controls not carefully designed for the maximum amount of wash water to be generated

MAINTENANCE REQUIREMENTS:

Inspect regularly

Remove sediment from wheel cleaning device before sediment accumulates to half the depth of the device

Remove sediment from sediment traps before it reaches a depth of half the design depth or 12 inches, whichever is less

Dewater and clean wash basins using dewatering controls

APPLICATIONS

Perimeter Control

Slope Protection

Sediment Barrier

Channel Protection

Temporary Stabilization

Final Stabilization

Waste Management

Housekeeping Practices

Fe=N/A

IMPLEMENTATION

CONSIDERATIONS

● Capital Costs

● Maintenance

◒ Training

○ Suitability for Slopes > 5%

Other Considerations:

Management of wash water

Prohibitions on the discharge of soaps and petroleum products

TARGETED POLLUTANTS

● Sediment

○ Nutrients & Toxic Materials

○ Oil & Grease

○ Floatable Materials

○ Other Construction Wastes



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3.16.1 Primary Use Wheel cleaning systems are used to remove soil from construction vehicles and equipment before they leave the site and enter paved streets. Wheel cleaning systems are used with a stabilized construction exit to minimize the tracking of soil from disturbed areas. They provide added protection and reduce the need to remove sediment from streets.

3.16.2 Applications Wheel cleaning systems can be used on any construction site where a stabilized construction exit is not adequate to prevent off-site tracking of soil. However, because of their cost, they are most applicable for:

Sites with large areas (> 10 acres) that are disturbed for long periods of time;

Sites with a large number of vehicles and/or heavy equipment entering and exiting the site, which that will quickly and repeatedly degrade rock exits;

Sites with clay soils or wet site conditions that result in tires accumulating large amounts of soil; or

Sites where contaminated soils might be present.

3.16.3 Design Criteria

General

Provide separate entrances and exits to the construction site so that incoming vehicles do not drive through the wheel cleaning system. Signage and employee training is critical to making the system work.

Wheel cleaning systems should be located within the stabilized construction exit so that the vehicle does not pick up additional sediment load by traversing disturbed areas. A minimum of 25 feet of stabilized exit shall be maintained between the cleaning system and the paved road.

The stabilized exit shall be sloped at 1 percent toward the cleaning system.

The width of the stabilized exit may be reduced to 10 to 20 feet, depending on the size and number of vehicles using the exit, as long as all exiting traffic is funneled through the cleaning system.

Post a sign requiring all vehicles to use the cleaning system before leaving the site. Posted speed limit through the wheel cleaning system should be 5 mph.

Wheel cleaning systems should be designed with ease of access to areas where sediment will accumulate, so the system can be frequently cleaned.

Rumble Racks

The minimum cleaning system shall consist of 10 foot wide, 8 foot long, steel grates with individual bars of the grates at varying heights to shake the vehicle and knock off soil. These grates are also known as rumble racks.

Minimum length of the rumble rack shall be the length of the circumference of the largest tire on vehicles that will be using the construction exit. Two to three lengths of grates are typically necessary to provide adequate soil removal, depending on soil type and size of vehicles.

Grates shall be placed over an excavated pit that is a minimum of one foot deep.

Grates may be purchased pre-made from vendors or constructed by welding 10 foot lengths of structural steel tubing (rectangular section) or angle. The lengths of steel (“bars” of the rumble rack) should be welded to steel beams or other cross supports in a manner that provides for alternating heights. This is accomplished with rectangular steel tube by alternating the long and short sides of



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the tube upward. Angle iron, welded to the support structure with the angle pointed upward, may also be used. Round tubing shall not be used, as it does not adequately shake the tires.

Size and spacing of bars and support beams shall be designed based on the size and weight of vehicles expected to be using the rumble rack.

Welded or manufactured grates may be cleaned and re-used on multiple projects.

Wheel Washes

Two common types of wheel wash systems constructed onsite are the corrugated metal wheel wash and the flooded basin wheel wash. In addition, several companies manufacture packaged wash systems that can be assembled onsite and re-used. All of these require a source of water, and several of the packaged systems require electricity to run pumps for water pressure.

All wheel washes must provide a means to collect the wash water in a sediment basin or other sediment control that provides equivalent or better treatment prior to discharge from the site.

For the flooded basin wheel wash, sedimentation occurs in the wash basin, meaning the basin cannot be used for a period of time while settling is allowed to occur. Cleaning of the basin should be done first thing in the morning after particles have settled overnight, and ideally the basin would be cleaned on Monday after settling all weekend. If the basin is pumped for cleaning, it should be accomplished using the controls in Section 3.3 Dewatering Controls.

Corrugated metal wheel washes shall be constructed over a drainage swale that conveys the wash water to a sediment barrier, typically a sediment basin. However, a passive or active treatment system may be needed to adequately remove suspended solids depending on the permit requirements for the site.

Swales, sediment basins, stone outlet sediment traps, and other controls for the wash water must be sized for the anticipated flows from the wheel wash using criteria in their respective sections of this manual. Depending on the volume of water, two sediment controls may be needed in parallel, to allow for settling and cleaning of one sediment control while the other is in operation for the wheel wash.

Manufactured wash systems frequently collect, filter, and recycle the wash water, resulting in the use of less water and producing less wash water to treat for sediment removal. For this reason, they may be more cost-effective over the life of the project, even if their initial cost is higher.

If a packaged wheel wash system does not include a sediment collection area, then a swale and sediment trap is required, similar to the corrugated metal wheel wash.

Prohibit the use of soap for wheel washing. The purpose of a wheel wash is to remove soil that would otherwise fall off on the roadway, not to clean the vehicle. Refer to Section 4.10 Vehicle and Equipment Management for proper vehicle washing procedures. The discharge of wash water with soap in it is prohibited, and soap is not removed by a sediment control.

Train employees to only use water in the wheel wash for removing accumulations of soil from the wheels and undercarriage. Minimize water contact with other portions of the vehicle or equipment. Wash water contaminated with oil, grease or fuel requires special handling and disposal. Refer to Section 4.10 Vehicle and Equipment Management.

3.16.4 Design Guidance and Specifications No specification for construction of this item is currently available in the Standard Specifications for Public Works Construction – North Central Texas Council of Governments.



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3.16.5 Inspection and Maintenance Requirements Wheel cleaning systems should be inspected regularly (at least as often as required by the TPDES Construction General Permit). Systems should be cleaned frequently, at least weekly and sometimes daily, to ensure proper operation. Grated systems should be cleaned before sediment accumulates to half the depth of the pit below the grates. Depending on volume of traffic, flooded basin systems often needed daily pumping, cleaning and refilling to be effective.

The sediment basin or other sediment trapping device shall be inspected for damaged areas and repaired as necessary. Sediment that has accumulated in the wash water sediment control (must be removed before it reaches half the design depth of the device or 12 inches, whichever is less. The removed sediment shall be stockpiled or redistributed to areas of the site that are protected by erosion and sediment controls.

Water that ponds in the sediment basin should be inspected for sheen. If sheen is present, the water is considered contaminated by a petroleum product. Regulations of the TCEQ require this water to be pumped into containers and disposed of appropriately. It is not an authorized discharge from the construction site. Proper vehicle and equipment maintenance is essential to preventing this problem from occurring.

Manufacturer’s recommendations should be followed for cleaning and maintaining packaged wheel wash systems.

3.16.6 Example Schematics The following schematics are example applications of the construction control. They are intended to assist in understanding the control’s design and function.

The schematics are not for construction. They may serve as a starting point for creating a construction detail, but they must be site adapted by the designer. In addition, dimensions and notes appropriate for the application must be added by the designer.



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Figure 3.36 Schematics of Rumble Rack Wheel Cleaning



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Figure 3.37 Schematics of Corrugated Metal Wheel Wash (Source: Modified from California Stormwater Quality Association BMP Handbook BMP Detail TC-1)



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Figure 3.38 Schematics of Flooded Basin Wheel Wash (Source: Modified from Oregon Department of Environmental Quality Erosion and Control Sediment Manual Detail SC-11)

Documents

3.16 Wheel Cleaning Systems - City of Denton · Wheel Cleaning Systems CC-172 April 2010, Revised 9/2014 E-172 3.16.1 Primary Use Wheel cleaning systems are used to remove soil from