WSDOT encourages material and waste recycling when possible. Since waste disposal can be costly and impact project schedules, WSDOT performs HazMat HazMat investigations and sampling to characterize HazMat prior to construction. Ultimately WSDOT is responsible for the proper reuse or disposal of project waste materials, including soils. The WSDOT Standard Specifications Section 2-01.2, Section 2-02.3, and Section 2-03.3(7) address the reuse and disposal of solid wastes during construction. WSDOT staff should contact a WSDOT HazMat Specialist with questions about any of the topics discussed below.
Recycling and Reuse
WSDOT encourages the use of recycled content materials on construction projects and reducing the amount of construction and demolition debris sent to landfills. WSDOT contractors have the option to purchase recycled products when contracted to work on WSDOT projects. Currently, WSDOT specifications allow for recycled content in the following products:
- Pavement mixtures (consisting of blast furnace slag or coal fly ash and Recycled Asphalt Pavement or "RAP").
- Guardrail posts and blocks
In addition, the following products, if generated and processed on-site to meet specifications, can be reused on a construction project:
- Broken concrete
- Ground asphalt
- Wood waste as defined by Section 2-01.2, Disposal of Usable Material and Debris (see below)
- Excavated soils (includes minimally contaminated soils with appropriate County approvals)
The following WSDOT Standard Specifications allow contractors to reuse or purchase the recycled materials identified above. Additional recycled products will be evaluated for conditional use through the WSDOT New Products Committee upon the appropriate testing through the WSDOT Materials Laboratory.
- Section 2-01.2 encourages the contractor to sell useable timber, chips, firewood, etc.
- Section 2-02.3(3) allows broken pavement and concrete to be incorporated in embankments.
- Section 5-04.2 allows that up to 20% recycled asphalt pavement (RAP) may be used in the manufacture of hot mix asphalt (HMA).
- Section 5-04.3(14) requires that debris from planning HMA become the property of the contractor. This material may be used as noted above, and is also a marketable product that they can use for other public and private work.
- Sections 5-05 and 6-02 allow fly ash and ground granulated blast furnace slag to be added to concrete.
- Sections 8-01 and 8-02 have numerous uses for compost.
- Section 9-03.21 list requirements for using various recycled materials (RAP, Concrete rubble, glass aggregate, steel furnace slag) in place of virgin aggregates for the various types of aggregates used in highway construction.
- Section 9-16.3(2) allows for guardrail blocks made from recycled materials per NCHRP Report 350.
Cleanup Options During Construction
When a WSDOT project encounters contaminated soil or water, an immediate cleanup is not typically required. The WSDOT PE decides the level of cleanup that is feasible based on the construction schedule and budget, the apparent extent of contamination, and the intended future use of the site. Due to the potential for substantial project delays and disposal costs, WSDOT does not “chase” contamination when the extent is unknown.
Depending on the factors mentioned above the following options may be chosen to address additional unexcavated contaminated soil.
Option 1: Remove All Contaminated Soil within WSDOT Right of Way
WSDOT PEs uses this option for small, localized areas of contamination where removal and disposal will not substantially impact the construction schedule and budget. This option minimizes WSDOT’s future liability.
Unless WSDOT identifies contamination during project scoping and is able to budget for remediation activities, it is generally not possible to use construction project funds for complete cleanup of a site. Project funds should only be used if WSDOT causes or spreads the contamination, contamination increases WSDOT’s liability, or Ecology determines the site is an immediate threat to human health or the environment and it imposes an administrative order on WSDOT to immediately perform remedial actions.
Option 2: Partially Remove Contaminated Soil outside Planned Excavation Limits
WSDOT PEs may decide to remove contamination in limited areas to the extent the project budget allows. These limited areas may include environmentally sensitive areas, areas where the final construction would prohibit additional future cleanup, or where removing contamination would ensure that construction does not cause contamination to spread.
Option 3: Leave Contamination in Place
Although all soil removed from the project must be disposed of properly, the WSDOT PE may decide to leave contamination in place outside of planned excavation areas. This option is appropriate for contamination that is not considered an immediate risk to human health or the environment and where project work will not create a preferential pathway for contamination to spread (e.g., utility lines). If Ecology determines there is an immediate risk, Ecology may issue an order requiring cleanup. The PE should contact a WSDOT HazMat Specialist if a project will leave contamination in place.
Leaving contamination in place minimizes impacts to the project schedule and budget and is legally permissible; however, this option increases WSDOT’s risk for future cleanup liability. Performing cleanup after construction is complete can be costly due to rising costs of site investigations, monitoring, equipment mobilization, labor, and disposal fees. If WSDOT was required to perform cleanup after construction, the agency would need to seek additional funding sources other than project construction funds (e.g., legislative requests).
Contaminated Soil and Water Disposal
WSDOT follows the steps outlined on the Identifying and Sampling Hazardous Materials web page for collecting soil and water samples. WSDOT usually characterizes samples for disposal based on the requirements of the selected disposal facility and the local County Health Department. If WSDOT characterizes contamination prior to construction, the Contractor disposes of the material in accordance with the project Special Provisions. WSDOT HazMat Specialists are available to assist PEs with obtaining any necessary waste disposal authorizations and can work with disposal facilities to obtain approval for direct haul during construction. If at any point sample results show that a material is a dangerous waste, WSDOT follows the steps for Dangerous Waste Disposal.
Soils that WSDOT cannot reuse on-site are taken off-site for treatment or disposal based on analytical results. The cost for disposal of contaminated soils that are not considered dangerous waste ranges from $35 to $50 per ton (not including time and materials for transportation). Disposal costs for soils that are considered dangerous waste range widely from $50 to $900 per ton.
WSDOT may be able to infiltrate or treat water with low levels of contaminants on-site or discharge the water to a sanitary or storm sewer. WSDOT works with the appropriate regulatory agency to determine the discharge criteria. Water that needs additional treatment is taken to an off-site treatment facility. Typical costs for water disposal range from $0.25 to $2.50 per gallon.
Dangerous Waste Disposal
WSDOT follows the steps on the Reporting Hazardous Materials web page to determine that a waste designates as a Dangerous Waste. With analytical data and a RCRA Site ID Number, if required, WSDOT can work with a contractor to complete the Uniform Hazardous Waste Manifest. This form is necessary for transporting the waste for treatment or disposal. Dangerous Waste is disposed of in a RCRA Subtitle C hazardous waste landfill. WSDOT maintains copies of all disposal paperwork in the project file. WSDOT PEs supplies copies of the paperwork to a WSDOT HazMat Specialist who assists with completing the Dangerous Waste Annual Report for Ecology.
The cost for disposal of Dangerous Waste varies greatly depending on the type of material and the analytical results. Disposal costs can range from $50 per ton to $900 per ton, not including time and materials for transportation.
Asbestos-Containing Materials (ACM) Disposal
WSDOT identifies and removes ACM as discussed on the Identifying and Sampling web page and the HazMat Special Provisions web page, respectively. Once an asbestos abatement is complete, abatement contractors take ACM to a permitted, lined landfill for disposal. Local Clean Air Agencies generally regulate air quality and have specific requirements for how to handle ACM during demolition and transport. Most air agencies also provide a list of landfills within their jurisdictions that will accept ACM. Abatement contractors are responsible for contacting the selected disposal facility in advance to verify disposal timelines and requirements and ensure that all waste shipment paperwork is complete.
Asbestos Cement Water Pipe
WSDOT prefers that projects remove and dispose of asbestos cement water pipe that is no longer in service. However, some Clean Air Agencies exclude this pipe from the normal disposal requirements and provide alternative disposal methods. These methods may include burying the pipe in place and covering with non-asbestos fill material. If a WSDOT PE would like to leave asbestos cement pipe in place they should consult with a WSDOT HazMat Specialist. When a project decides to leave asbestos cement pipe in place, the PE must add documentation including the exact location of the pipe to the project file.
Lead-Based Paint (LBP) Waste
Lead-based paint poses disposal challenges due to the toxicity of metals and the potential for the waste to designate as a dangerous waste (per Chapter 173-303 WAC). WSDOT Contractors characterize LBP waste from bridge painting projects in accordance with WSDOT Standard Specification 6-07.3(10)F. For all projects, WSDOT must meet the requirements of the selected disposal facility.
Scenarios when LBP is generally NOT a dangerous waste:
- LBP on metal where the paint is considered a product (not a waste) that is serving its original purpose of preventing corrosion.
- Scrap metal coated with LBP that will be recycled and is excluded from the dangerous waste regulations (WAC 173-303-071(ff)).
- LBP that is removed during bridge painting projects by abrasive blasting using an additive that stabilizes the waste and renders it non-hazardous.
When WSDOT characterizes LBP samples for disposal the following steps often apply:
- Analyze sample for total lead and other RCRA 8 total metals (includes Ag, As, Ba, Cd, Cr, Hg, Pb, Se).
- Perform a follow-up Toxicity Characteristic Leaching Procedure (TCLP) analysis.
- Individual metals that have total concentrations less than or equal to 20 times the TCLP limit are usually not run.
- Designate the material as a dangerous waste per the Dangerous Waste Regulations.
Specifically for lead, if the TCLP results are greater than 5 milligrams per liter (mg/L) the material designates as a dangerous waste with a waste code of D008. In this case, WSDOT follows the procedures outlined on the Reporting Hazardous Materials web page. Dangerous waste is disposed of at a RCRA Subtitle C hazardous waste landfill (see the Dangerous Waste Disposal section of this page for additional information). If the LBP waste does not designate as a dangerous waste, WSDOT would dispose of the waste at a RCRA Subtitle D solid waste landfill.
Creosote Treated Wood
Ecology regulates the disposal of creosote and other treated wood wastes. Creosote treated wood must be disposed of or reused within 180 days following removal from use. Creosote treated wood typically falls under the “wood treated with other preservatives” exclusions from dangerous waste designation per WAC 173-303-071. Municipal solid waste/ RCRA Subtitle D landfills (Chapter 173-351 WAC) will typically accept creosote-treated wood without analytical testing. Creosote treated wood may also be burned for energy recovery in an industrial furnace or boiler. WSDOT Contractors should contact facilities prior to transporting waste for specific requirements. Reuse of creosote treated wood is the recommended disposal method per Ecology’s January 2003 Publication 03-04-038 (pdf 109 kb). WSDOT Staff can contact a WSDOT HazMat Specialist with questions about disposing of treated wood.