Foundry Sand Reuse in Oklahoma

Planning to reuse spent foundry sand in Oklahoma? This guide covers the rules that apply, the tests that decide how the sand can be managed, and what DEQ 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 Oklahoma, DEQ decides case by case whether a proposed reuse is allowed.

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.

Oklahoma’s beneficial reuse rule

Oklahoma’s beneficial reuse rule is OAC 252:515-1-7. On request, and with supporting documentation, DEQ may determine that a material is not a solid waste when it is:

1. used as an ingredient in an industrial process to make a product;
2. used as an effective substitute for a commercial product;
3. returned to the original process that generated it, without first being reclaimed, as a substitute for raw material feedstock, when that process uses raw materials as its main feedstock; or
4. held by someone with the equipment to process it so that it meets one of the conditions above.

DEQ may also approve other reuse proposals. It weighs the intended use and the possible effects on human health and the environment.

Stockpiles have a limit. Material held for future markets, or held in amounts greater than can reasonably be used or recycled within one year, stays regulated as solid waste.

Applying to DEQ

• Who files: only the waste generator can submit a Beneficial Reuse Request.
• How: create an account in DEQ’s online reporting system and select ‘Beneficial Reuse Requests.’
• Scope: each application covers one waste material and one reuse method.
• Changes: a new application is required when submitted information changes, including the reuse location, volume, generating process, or analyses.
• Sampling: after review, DEQ may provide a sampling protocol and a list of required analyses. You can submit existing results, but DEQ may require more testing.
• After approval: some approvals require annual renewal. DEQ may inspect the site to confirm the reuse matches the application. It may amend a determination if the reuse causes adverse conditions, and may revoke an approval at any time.
• Liquids and sludge: liquids, sludge, and wastes from OPDES-permitted industrial wastewater impoundments follow the Water Quality Division route, not this solid-waste application. Call (405) 702-8100.

DEQ solid waste compliance: (405) 702-5100, solidwastereports@deq.ok.gov.

Hazardous waste determination

Oklahoma adopts the federal hazardous waste rules (40 CFR Parts 124 and 260–279) by reference in OAC 252:205-3-1.

Under 40 CFR 262.11, 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.

Small and large quantity generators must keep records supporting the determination for at least three years after the waste was last sent for treatment, storage, or disposal.

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, DEQ, 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.

DEQ bases its required analyses on the material and the process that generated it.

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.

DEQ approves reuse case by case. Check any destination and proposed use with DEQ before scheduling delivery.

When you talk to DEQ, describe the proposal using the categories in OAC 252:515-1-7. For example, is the sand a concrete ingredient, or a substitute for purchased fill sand? Get the receiving site’s specifications and written acceptance. If reuse is not cleared, arrange disposal that fits the waste determination.

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.

Storage and records

Store spent sand on a defined pad or in bins, control dust and runoff, and keep other foundry wastes out. Plan volumes so stored sand can be used within one year; material held longer stays regulated as solid waste under OAC 252:515-1-7(c).

Keep the waste determination, lab reports, DEQ approvals, and the receiving site’s acceptance together. Record tonnage shipped, dates, and destinations. Keep determination records for at least three years.

Before pickup

1. Identify the alloys cast, sand and binder systems, separate streams, monthly volume, and plant location.
2. Make the hazardous waste determination and complete the required tests.
3. Choose a destination and get its material specifications.
4. File or confirm the DEQ Beneficial Reuse Request for that sand and use.
5. Get written acceptance and arrange pickup.

Common questions

Rules and guidance

• Oklahoma DEQ: Beneficial Reuse Requests
• OAC 252:515-1-7: Beneficial reuse
• OAC 252:515: Management of Solid Waste
• OAC 252:205: Hazardous Waste Management (DEQ rule text)
• 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