Foundry Sand Reuse in Washington

Planning to reuse spent foundry sand in Washington? This guide covers the rules that apply, the tests that decide how the sand can be managed, and what Ecology needs before the sand can be reused.

Key terms

Spent foundry sand

Foundries bond silica sand into molds and cores for casting metal. The sand is reused many times in the plant. Spent foundry sand is molding and core sand that can no longer make molds or cores.

Green sand and chemically bonded sand

Green sand is bonded with clay, usually bentonite, plus water and additives such as carbon. Chemically bonded sand uses resin binders. Most cores are chemically bonded. The binder system affects what the spent sand contains.

Beneficial reuse

Beneficial reuse puts a waste material to productive use instead of disposing of it. In Washington, Ecology approves it through a beneficial use determination (BUD), a statewide exemption from solid waste permitting.

TCLP

The Toxicity Characteristic Leaching Procedure (EPA Method 1311) measures how much of certain contaminants can leach from a sample. It is one part of deciding whether a waste is hazardous.

What’s in your spent sand?

Spent sand carries what the casting process added: binder residue, metal fines, and burnt core material. The alloy matters most. Sand from iron, steel, and aluminum foundries is the most commonly reused. Sand from leaded brass and bronze foundries is often regulated as hazardous waste.

Keep each stream separate. Baghouse dust, shotblast fines, cupola slag, broken cores, and core room sweepings need their own evaluation. Mixing them into spent sand can change how the whole load is managed. Track the alloys cast, the binder system, and any process changes.

Washington’s beneficial use rule

Washington’s beneficial use rule is WAC 173-350-200. Once Ecology approves an application, the original applicant’s use of that solid waste is exempt from solid waste permitting anywhere in the state, on the approval’s terms. Ecology grants an exemption only for uses it finds do not threaten human health or the environment.

Each use needs its own BUD. The rule section for uses exempt by rule, WAC 173-350-200(7), is reserved.

Every approved use must meet general conditions, including these:

1. Make sure the material is not a dangerous waste under chapter 173-303 WAC.
2. Do not dilute the waste to lower its contaminant levels in place of treatment or disposal.
3. Meet the performance standards of WAC 173-350-040.
4. Keep material for beneficial use separate from waste headed for disposal or other destinations.
5. Store it under chapter 173-350 WAC unless Ecology approves other storage during review.
6. Report any accidental release to Ecology and the local health department immediately.
7. Allow Ecology and the local health department to inspect where the material is stored or used.
8. Submit an annual report to Ecology by April 1 with the exemption number and the amount used.

The rule limits fill uses. A proposal to use solid waste as part of fill must show the material meets specific engineering needs other than occupying space. A professional engineer registered in Washington must certify it. Alternative daily cover at landfills is outside this rule. It needs approval through the landfill’s solid waste permitting or the local health department.

Applying to Ecology

• Who files: the applicant files with Ecology. The application names the waste generator and the applicant, with the business identifier numbers for the generator and any third-party handler.
• How: submit Ecology’s General Application for Beneficial Use Exemption (ECY 040-147) with a State Environmental Policy Act (SEPA) checklist.
• Contents: describe the sand, the ingredients of the original product, and the proposed use. Include evidence the sand will perform as claimed, how it will be transported, what contributes contaminants to it, and a schematic of the foundry’s operations showing where wastes are generated, treated, or stored. Explain how you will meet the general conditions.
• Review: Ecology notifies you when the application is complete. It then posts it for at least 45 days of public comment. Ecology decides in writing within 90 days after receiving a complete application.
• Changes: changing the application or adding information during public review withdraws the completeness determination. Review then restarts.
• After approval: the BUD lasts as long as the material and use stay consistent with the proposal. Ecology may add requirements. It may require a solid waste handling permit if conditions are not met, information was misrepresented, or new information shows a threat.
• Appeals: appeal a decision to the Pollution Control Hearings Board within 30 days.

Ecology’s BUD coordinator: (360) 522-6852. Mail: Beneficial Use Determination Coordinator, Washington Department of Ecology, PO Box 47775, Olympia, WA 98504-7775.

Dangerous waste designation

Washington regulates hazardous waste under its own Dangerous Waste Regulations, chapter 173-303 WAC. The rule uses the term “dangerous waste” and adds state-only criteria to the federal lists and characteristics.

If spent sand is not a listed or characteristic waste, check the state-only criteria in WAC 173-303-100 next. Toxicity uses book designation from known constituents, or a fish bioassay. For persistence, a total PAH concentration above 1.0% makes the waste extremely hazardous (WP03). Halogenated organic compounds at 0.01% or more also designate. A waste can pass the federal tests and still be a dangerous waste.

Solid state-only dangerous waste is “special waste” when it is corrosive, has Category D toxicity, is PCB waste, or is persistent but not extremely hazardous (WAC 173-303-040). Under WAC 173-303-073, it can be managed outside most dangerous waste rules if it meets that rule’s standards. It must be disposed of in a qualifying landfill, legitimately recycled, or treated on site. Waste EPA regulates as hazardous, such as sand that fails TCLP for lead, cannot be special waste.

Under WAC 173-303-070, the foundry must decide whether its spent sand is hazardous:

1. Make the determination at the point of generation, before mixing or dilution. Repeat it if the waste may have changed.
2. Check whether the waste is excluded from the hazardous waste rules.
3. Check whether it matches a listed hazardous waste.
4. Check for hazardous characteristics, including toxicity. Use knowledge of the materials and process, testing, or both. Test when knowledge alone is not enough.

Washington requires generators to keep determination records for at least 5 years.

TCLP testing and limits

Tell the lab the alloys cast, the binder system, and which streams the sample includes. Use representative samples. Agree on the sampling plan with the lab, Ecology, and the receiving site before collecting.

A waste is hazardous for toxicity if its TCLP extract meets or exceeds any limit in 40 CFR 261.24. The limits for the RCRA metals are:

Passing TCLP addresses toxicity for the substances tested. It does not approve reuse or rule out other reasons a waste may be hazardous. See material testing for sampling basics.

For state-only toxicity, use book designation or a fish bioassay. When the two disagree, the bioassay result controls (WAC 173-303-100(5)). Find PAH and halogenated organic concentrations by knowledge of the waste or by testing. Ecology may require testing when it has reason to believe a waste may designate (WAC 173-303-070(4)).

Finding a reuse destination

EPA’s 2014 risk assessment found three uses protective of health and the environment for silica-based spent sand from iron, steel, and aluminum foundries: manufactured soil, soil-less potting media, and road subbase. EPA and USDA support those uses. The finding does not cover sand from brass or bronze foundries, olivine sand, or sand mixed with other foundry wastes such as baghouse dust or cupola slag. EPA defers to state programs, so the state rules on this page still decide each use.

Ecology decides each use through the BUD process. Check any destination and proposed use with Ecology before scheduling delivery.

A BUD requires a material that is not a dangerous waste. If spent sand designates as special waste, ask Ecology which route applies before planning reuse. Ecology keeps a public registry of pending, approved, and terminated BUDs. Get the receiving site’s specifications and written acceptance. If reuse is not cleared, arrange disposal that fits the waste designation.

Worker protection

• Silica: foundry sand is mostly crystalline silica. OSHA’s general industry standard, 29 CFR 1910.1053, sets a permissible exposure limit of 50 µg/m³ of respirable crystalline silica as an 8-hour average. Exposure assessment starts at the 25 µg/m³ action level.
• Construction use: crews placing sand as fill or subbase fall under the construction silica standard, 29 CFR 1926.1153.
• Lead: brass and bronze foundries that cast leaded alloys also follow OSHA’s lead standard, 29 CFR 1910.1025.
• Dust: control dust during shakeout, storage, and loading.

Washington L&I Division of Occupational Safety and Health (DOSH) runs Washington’s OSHA-approved State Plan. For most employers, its standards apply in place of federal OSHA and must be at least as effective.

Storage and records

Store spent sand on a defined pad or in bins, control dust and runoff, and keep other foundry wastes out. Store sand awaiting beneficial use under chapter 173-350 WAC unless the BUD approves other storage.

If you manage spent sand as special waste, follow WAC 173-303-073. Store it to prevent releases. Do not hold it on site more than 180 days after the amount exceeds 2,200 pounds, and record when accumulation began. Send it with a document naming the waste, amount, origin, generator, and destination. Keep records of the receiving facility’s receipt for at least five years.

Keep the designation, lab reports, Ecology approvals, and the receiving site’s acceptance together. Record tonnage shipped, dates, and destinations. Keep designation records for at least five years after the waste last leaves for treatment, storage, or disposal (WAC 173-303-210).

Before pickup

1. Identify the alloys cast, sand and binder systems, separate streams, monthly volume, and plant location.
2. Designate the waste, including Washington’s state-only criteria, and complete the required tests.
3. Choose a destination and get its material specifications.
4. Apply for or confirm the Ecology BUD for that sand and use.
5. Get written acceptance and arrange pickup.

Common questions

Rules and guidance

• Ecology: Beneficial use determinations
• WAC 173-350-200: Beneficial use permit exemptions
• Ecology: General Application for Beneficial Use Exemption (ECY 040-147)
• Ecology: Beneficial use determinations registry
• Chapter 173-303 WAC: Dangerous Waste Regulations
• WAC 173-303-070: Designation of dangerous waste
• WAC 173-303-073: Conditional exclusion of special wastes
• WAC 173-303-100: Dangerous waste criteria
• WAC 173-303-210: Generator recordkeeping
• Ecology: Washington state-only criteria
• 40 CFR 262.11: Hazardous waste determination
• 40 CFR 261.24: Toxicity characteristic
• EPA Method 1311: TCLP
• EPA: Beneficial Uses of Spent Foundry Sands
• EPA: Risk Assessment of Spent Foundry Sands in Soil-Related Applications
• 29 CFR 1910.1053: Respirable crystalline silica
• 29 CFR 1926.1153: Respirable crystalline silica in construction
• Washington L&I Division of Occupational Safety and Health (DOSH)