The potential for contamination of stormwater or flowing waters by vehicle fluids, fuels, or washwater necessitates environmental stewardship practices. To protect on-site watercourses:

• Refuel machinery at locations well removed from the watercourse (recommended minimum 100 m or 300 ft. separation)
• Wash and service vehicles and machinery at locations well removed from the watercourse.
• Use bio-friendly hydraulic fluids in equipment operating in or adjacent to watercourse.
• Store fuel, lubricants, hydraulic fluid and other potentially toxic materials at locations well removed from the watercourse.
• Isolate storage areas so that spilled fluids cannot enter the watercourse.

Vehicle and equipment cleaning procedures and practices are typically used to minimize or eliminate the discharge of pollutants from vehicle and equipment cleaning operations to storm drain systems or watercourses. On-site vehicle and equipment washing are often discouraged, to minimize runoff problems. Caltrans has developed the following construction vehicle cleaning environmental stewardship practices: [N]

• When vehicle/equipment washing/cleaning must occur onsite, and the operation cannot be located within a structure or building equipped with appropriate disposal facilities, the outside cleaning area shall have the following characteristics, and should be arranged with the construction stormwater coordinator. Vehicle washing should occur only at designated pre-wash areas, facility wash racks or other designated areas:
• Special areas should be designated for washing vehicles. Whether at pre-wash areas at the maintenance facility or the field, vehicle and equipment wash water should be discharged to a sanitary sewer, or contained for percolation or evaporative drying away from storm drain inlets or watercourses. The latter should be located where the wash water will spread out and evaporate or infiltrate directly into the ground, or where the runoff can be collected in a temporary holding or seepage basin.
  • Locate away from storm drain inlets, drainage facilities, or watercourses. Wash waters should not be discharged to storm drains or watercourses.
  • Pave with concrete or asphalt and bermed to contain wash waters and to prevent run-on and runoff.
  • Configure with a sump to allow collection and disposal of wash water.
  • Use only when necessary.
• Apply sediment control BMPs if applicable. Wash areas should have gravel bases to minimize mud generation.
• Vehicles such as cement or dump trucks and other construction equipment should not be washed at locations where the runoff will flow directly into a watercourse or stormwater conveyance system.
• Minimize use of solvents. The use of diesel for vehicle and equipment cleaning should not be allowed. Cleaning of vehicles and equipment with soap, solvents or steam should not occur on the project site unless the Resident Engineer (RE) has been notified in advance and the resulting wastes are fully contained and disposed of outside the highway right‑of‑way in conformance with specifications. Resulting wastes and by-products should not be discharged or buried within the highway right-of-way, and should be captured and recycled or disposed according to Liquid Waste Management BMPs or Hazardous Waste Management BMPs, depending on waste characteristics.
• Vehicle and equipment wash water should be contained for percolation or evaporative drying away from storm drain inlets or watercourses and should not be discharged within the highway right-of-way. Sediment control BMPs should be applied if applicable.
• All vehicles/equipment that regularly enter and leave the construction site should be cleaned off-site.
• When cleaning vehicles/equipment with water:
  • Use as little water as possible. High pressure sprayers may use less water than a hose, and should be considered.
  • Use positive shutoff valve to minimize water usage.
  • Facility wash racks should discharge to a sanitary sewer, recycle system or other approved discharge system and should not discharge to the storm drainage system or watercourses.
• When possible, truck beds should be cleaned using a dry cleaning technique (sweep up or shovel out).
• The control measure should be inspected at a minimum of once a week.
• Monitor employees and subcontractors throughout the duration of the construction project to ensure appropriate practices are being implemented.
• Inspect sump regularly and remove liquids and sediment as needed or as directed by the RE.

Vehicle and equipment fueling procedures and practices are designed to minimize or eliminate the discharge of fuel spills and leaks into storm drain systems or to watercourses. These procedures are applied on all construction sites where vehicle and equipment fueling takes place.[N]

• Onsite vehicle and equipment fueling should only be used where it's impractical to send vehicles and equipment off-site for fueling
• When fueling occurs onsite, the contractor shall select and designate an area to be used, subject to approval of the Resident Engineer (RE).
• Absorbent spill clean-up materials and spill kits should be available in fueling areas and on fueling trucks and should be disposed of properly after use.
• Drip pans or absorbent pads should be used during vehicle and equipment fueling, unless the fueling is performed over an impermeable surface in a dedicated fueling area.
• Dedicated fueling areas should be protected from stormwater run-on and runoff, and should be located at least 15 m (50 ft) from downstream drainage facilities and watercourses. Fueling must be performed on level-grade areas.
• Nozzles used in vehicle and equipment fueling should be equipped with an automatic shut-off to control drips. Fueling operations shall not be left unattended.
• Use vapor recovery nozzles to help control drips as well as air pollution where required by Air Quality Management Districts (AQMD. Ensure the nozzle is secured upright when not in use.
• Fuel tanks should not be "topped-off."
• Vehicles and equipment should be inspected on each day of use for leaks. Leaks should be repaired immediately or problem vehicles or equipment should be removed from the project site.
• Absorbent spill clean up materials should be available in fueling and maintenance areas and used on small spills instead of hosing down or burying techniques. The spent absorbent material should be removed promptly and disposed of properly.
• Federal, state, and local requirements should be observed for any stationary above ground storage tanks.
• Mobile fueling of construction equipment throughout the site should be minimized. Whenever practical, equipment should be transported to the designated fueling area.
• Protect fueling areas with berms and/or dikes to prevent run-on, runoff, and to contain spills.
• Fueling areas and storage tanks should be inspected regularly.
• Keep an ample supply of spill cleanup material on the site.
• Immediately cleanup spills and properly dispose of contaminated soil and cleanup materials.

Vehicle and equipment maintenance procedures and practices are used to minimize or eliminate the discharge of pollutants to the storm drain systems or to watercourses from vehicle and equipment maintenance procedures. These procedures are applied on all construction projects where an onsite yard area is necessary for storage and maintenance of heavy equipment and vehicles.[N]

• Drip pans or absorbent pads should be used during vehicle and equipment maintenance work that involves fluids, unless the maintenance work is performed over an impermeable surface in a dedicated maintenance area.
• All maintenance areas are required to have spill kits and/or use other spill protection devices.
• Dedicated maintenance areas should be protected from stormwater run-on and runoff, and should be located at least 15 m (50 ft) from downstream drainage facilities and watercourses.
• Drip Pans or plastic sheeting should be placed under all vehicles and equipment placed on docks, barges, or other structures over water bodies when the vehicle or equipment is planned to be idle for more than one hour.
• Absorbent spill clean-up materials should be available in maintenance areas and should be disposed of properly after use. Substances used to coat asphalt transport trucks and asphalt spreading equipment should be non-toxic.
• Use off-site maintenance facilities whenever practical.
• For long-term projects, consider constructing roofs or using portable tents over maintenance areas.
• Properly dispose of used oils, fluids, lubricants, and spill cleanup materials.
• Do not dump fuels and lubricants onto the ground.
• Do not place used oil in a dumpster or pour into a storm drain or watercourse.
• Properly dispose or recycle used batteries.
• Do not bury used tires.
• Repair of fluid and oil leaks immediately.
• Provide spill containment dikes or secondary containment around stored oil and chemical drums.
• Maintain waste fluid containers in leak proof condition.
• Vehicle and equipment maintenance areas should be inspected regularly.
• Vehicles and equipment should be inspected on each day of use. Leaks should be repaired immediately or the problem vehicle(s) or equipment should be removed from the project site.
• Inspect equipment for damaged hoses and leaky gaskets routinely. Repair or replace as needed.

Waste and recycled materials (WRM) used in structural systems are required to satisfy material strength, durability, and leachability requirements. These materials exhibit a wide variety of characteristics, due to the diversity of industrial processes that produce them.[N]

A proposed methodology for assessing the environmental impact of leachates from pavements and other construction and repair materials on surface water and groundwater was developed and validated by NCHRP Project 4-21, Appropriate Use of Waste and Recycled Materials in the Transportation Industry. The researchers also studied the movement (or transport) and eventual fate of the soluble components of highway materials, including materials, preservatives, and additives present in the highway right-of-way. The methodology is intended to help highway agencies protect the environment and explain to the public why they are using—or not using—a particular material (new or recycled) in a construction and repair project. The methodology can be used as a management and decision-making tool for state highway engineers and managers, public interest groups, environmental advocacy groups, and regulatory agencies involved in reviewing new materials for highway construction and rehabilitation. The project delivered several key products:

• Baseline data on conventional (new and recycled) construction and repair materials.
• Laboratory protocols for integrated bioassay and chemical analysis.
• A computer model for screening and evaluating materials in highway settings.
• A recommended practice for screening and evaluating the impact of construction and repair materials on ground and surface waters.

The IMPACT software estimates the fate and transport of leachates from highway construction and repair materials in the environment surrounding the highway right-of-way. The project also contains an extensive, readily accessible database of laboratory test results for materials ranging from common construction and repair products to waste and recycled materials proposed for use in highway construction. A summary document titled Primer Environmental Impact of Construction and Repair Materials on Surface Water and Ground Water was published as NCHRP Report 443 . The revised final report is made up of five volumes: Volume I, Summary of Methodology, Laboratory Results, and Model Development; Volume II, Methodology, Laboratory Results, and Model Development for Phases I and II; Volume III, Methodology, Laboratory Results, and Model Development for Phase III; Volume IV, Laboratory Protocols; and Volume V, User's Guide, IMPACT. Volume I was published as NCHRP Report 448. All five volumes, the primer, and the IMPACT software have been distributed on CD-ROM as CRP-CD-7.[N]

Recycled materials that exhibited greater potential problems in terms of leachates, such as municipal solid waste combustor ash, were not included in the generally recommended practices below, though research on how to stabilize and utilize some of these potential aggregates continues. The RMRC at the University of New Hampshire also has a research project on the subject underway: Monitoring and Analysis of Leaching from Subbases Constructed with Industrial Byproducts.[N]