Foundry Sand Reuse in Missouri

Planning to reuse spent foundry sand in Missouri? This guide covers the rules that apply, the tests that decide how the sand can be managed, and what DNR 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 Missouri, DNR may grant a beneficial use exemption from the solid waste disposal area permit.

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.

Missouri’s beneficial use rule

Missouri’s beneficial use rule is 10 CSR 80-2.020(9)(B). DNR may exempt a project that beneficially reuses solid waste from the solid waste disposal area permit. You must show a beneficial use or reclamation, and the project must not create pollution, a public nuisance, or a health hazard.

DNR has granted some broad, general beneficial use exemptions. Most requests are evaluated case by case for a specific site and activity.

The same rule has two related provisions:

1. Using solid waste in processing or manufacturing products needs no permit (10 CSR 80-2.020(9)(A)5). It must create no pollution, public nuisance, or health hazard.
2. DNR may exempt small pilot or demonstration projects for a beneficial use for up to one year, after prior written approval (10 CSR 80-2.020(9)(C)).

Applying to DNR

• Who files: the person asking for the exemption. If someone else owns the site, include the owner’s signed statement approving the operation.
• How: send a detailed written request to DNR’s Waste Management Program explaining the project.
• What to include: the beneficial use, the site location, surrounding land use, and site characteristics. Add the amount of sand needed, the time to finish the project, and documentation of the sand’s source.
• Characterization: describe the physical and chemical characteristics of the sand, background soils, and nearby water quality, with lab data. Give sample locations and methods.
• Site plans: describe removal from the foundry, transport, placement, compaction, dust control, and erosion control. Add closure plans for cover and vegetation, a land-use map within 1,000 feet, and a management plan with a contingency plan.
• Other permits: include copies of any water or air permit applications and evidence of local zoning compliance.
• Groundwater: keep placed sand above the seasonal high groundwater table, unless the Water Pollution Control Program grants a variance.
• Decision: DNR replies in writing that the project is approved, not approved, or needs more information. If it is not approved, DNR explains why.

DNR Waste Management Program: 573-751-5401 or 800-361-4827, wmp@dnr.mo.gov.

Hazardous waste determination

Missouri adopts the federal hazardous waste rules by reference in 10 CSR 25. 10 CSR 25-4.261 adopts 40 CFR Part 261 with state changes. 10 CSR 25-5.262 adopts the July 1, 2024 edition of the federal generator standards in Part 262, with state additions.

Missouri generators register with DNR in place of the federal identification number rules in 40 CFR 262.18(a) and (c). A generator that reaches the monthly quantities in 40 CFR 262.13, Table 1, must register under the state rule.

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, DNR, 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 a beneficial use exemption, set the lab tests with DNR. They must include at least TCLP or modified TCLP for all applicable parameters, using EPA-approved methods.

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.

DNR decides reuse case by case. Check any destination and proposed use with DNR before scheduling delivery.

When you talk to DNR, describe the proposal using 10 CSR 80-2.020(9). For example, will the sand be an ingredient in a manufactured product, or placed at a project site? 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. An exemption request must describe how the sand is moved, placed, and compacted, and how dust and erosion are controlled. Follow those procedures once DNR approves them.

Keep the waste determination, lab reports, DNR 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. Contact DNR’s Waste Management Program, then file or confirm the beneficial use exemption for that sand, site, and use.
5. Get written acceptance and arrange pickup.

Common questions

Rules and guidance

• Missouri DNR: Beneficial Use
• 10 CSR 80-2.020: Permit issuance and exemptions
• 10 CSR 25-4.261: Methods for identifying hazardous waste
• 10 CSR 25-5.262: Standards for generators of hazardous waste
• 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