WSDOT construction projects provide great opportunities for both purchasing recycled content materials and for reducing the amount of construction and demolition debris being sent, on behalf of the state, to landfills.
Much of the construction and demolition debris being generated by WSDOT projects has value as a commodity and provides potential cost saving opportunities to WSDOT and/or its contractors. For example:
- The fee to recycle a load of recyclable construction debris is usually significantly lower than the cost to dispose of the same material in a landfill. For example, on a recent WSDOT project involving bridge demolition, concrete was sent to a recycling facility for a 95% cost savings compared to landfill disposal.
- Chipping clean wood/landclearing debris on-site and using it for landscaping/erosion control is often much cheaper than paying to have the material hauled to a licensed landclearing debris/compost facility and then paying for the chipped product and having it hauled back to the job site.
- Broken concrete from a job site can be crushed on-site to meet compaction specifications and used in a number of applications. This saves money over hauling, recycling, and buying and hauling new crushed rock.
Purchasing Recycled Materials
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 Standard Specifications for Road, Bridge, and Municipal Construction 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 planing 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.
Construction, Demolition, and Landclearing (CDL) Debris Off-Site Recycling
Exact figures are not available but as the largest developer in Washington State, it can be assumed that WSDOT generates a significant amount of solid waste (especially CDL debris) through construction and facility operations. For construction projects, waste disposal is a responsibility of the contractor per Section 2-02 and 2-03.3(7) of the Standard Specifications. Solid waste regulations are enforced at the County level through an ordinance, therefore disposal activities must be in compliance with that local regulation. Links to all 39 County level solid waste/recycling programs in Washington State are provided below.
Recycling / reusing CDL debris and purchasing recycled products for large construction projects is good for the environment by reducing energy (emissions) associated with landfilling and the need for raw materials. Likewise, it saves both contractors and taxpayers money by reducing transport and/or disposal costs. With the County approval, reusing and recycling CDL debris such as low level contaminated soil, broken asphalt, wood waste, etc. should always be considered by WSDOT contractors to reduce tipping fees, which can allow for lower bid estimates. In the case of contaminated soil, the WSDOT Hazardous Materials and Solid Waste Program should be consulted to develop a soil management plan for the Counties review and approval that can allow for reuse of this material rather than landfill disposal.
To assist contractors in recycling CDL debris, the following links provide more useful information.