Foundry Sand Reuse in Mississippi

Planning to reuse spent foundry sand in Mississippi? This guide covers the rules that apply, the tests that decide how the sand can be managed, and what MDEQ 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 Mississippi, MDEQ issues a beneficial use determination (BUD) for an eligible by-product and use.

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.

Mississippi’s beneficial use rule

Mississippi’s beneficial use rule is 11 Miss. Admin. Code Pt. 4, Ch. 9. MDEQ may consider a BUD when:

1. the material is a by-product: a solid waste generated in making a primary product that would otherwise go to a landfill or other disposal facility;
2. it is characterized well enough to show the use protects health and the environment and that it suits the use;
3. it is not putrescible and has no similar potential for nuisance;
4. it replaces a raw material or other feedstock and gives a comparable benefit;
5. the use does not serve solely to dispose of it; and
6. the use has a demonstrated use or market.

The sand must be nonhazardous as generated. Treating it to make it nonhazardous does not qualify it. MDEQ will not approve speculative accumulation for unproven uses or uses with no market. For an unproven use, MDEQ may approve a demonstration project first.

Uses fall into four categories:

• Category I: standing uses that need no application or annual report. They include a by-product used as a contained or encapsulated additive in making a product. They also include contained uses in a system MDEQ already regulates, such as alternate cover at a landfill or construction inside a lined landfill cell. The by-product must still meet the eligibility rules.
• Category II: engineered construction and other civil engineering uses.
• Category III: soil amendments, soil amendment additives, and direct land application.
• Category IV: all other uses. MDEQ may apply some or all of the Category II or III conditions.

Categories II to IV need a BUD before the use starts. For Categories II and III, the by-product should not exceed the total metals limits in Table A. A metal above Table A is then tested by TCLP against the Table B limits:

Category III uses must also stay within the Appendix 2 soil amendment limits, in mg/kg: arsenic 41, cadmium 39, copper 1,500, lead 300, mercury 17, molybdenum 18, nickel 420, selenium 36, and zinc 2,800. MDEQ may add constituents or require a risk assessment. If a by-product misses a standard, you may propose a risk-based demonstration instead.

Applying to MDEQ

• Who files: the generator, distributor or supplier, or end user. An applicant who is not the generator must include written consent from the generator or other owner of the material.
• How: complete MDEQ’s Request Form for a Beneficial Use Determination before the use begins. The first section covers the applicant; the second asks use-specific questions.
• Construction uses: for Category II, a Mississippi-licensed professional engineer must certify that the by-product suits the use. Where ASTM or other recognized standards exist, the by-product must meet them.
• Soil uses: for Category III, get certification from the Mississippi Department of Agriculture and Commerce where it applies. Tell end users in writing the acceptable agronomic rate and practices.
• Decision: MDEQ issues a BUD or denies the request in writing. You can appeal a denial or its conditions to the Commission on Environmental Quality within 30 days.
• Limits: a BUD covers uses in Mississippi only. It does not exempt you from water and air rules. MDEQ may modify, terminate, or rescind a BUD for just cause.
• After approval: report the prior year’s activity by February 28. Include the quantity used or distributed and a current characterization. If the process has not changed, a signed certification may replace new testing.

Contact MDEQ’s Beneficial Use Program through its program page.

Hazardous waste determination

Mississippi adopts the federal hazardous waste rules by reference in 11 Miss. Admin. Code Pt. 3, Ch. 1. Rule 1.2 adopts the identification rules in 40 CFR Part 261, and Rule 1.3 adopts the generator standards in Part 262.

Mississippi adds an annual report. A generator of more than 220 pounds of hazardous waste in any month of the prior year reports to MDEQ by March 1. This replaces the federal biennial report for those generators.

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, MDEQ, 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 Category II and III uses, analyze the primary chemical constituents and physical properties, and compare total metals to Table A. Each Table B leachate limit is one-tenth of the federal TCLP limit for that metal.

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.

Outside the Category I standing uses, MDEQ approves reuse case by case. Check any destination and proposed use with MDEQ before scheduling delivery.

When you talk to MDEQ, describe the proposal using the categories in Rule 9.3. For example, is the sand an encapsulated additive in a product, an engineered construction material, or a soil amendment? 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 approved by-product stays a solid waste until it is used. Until then, the transport and storage conditions in Rule 1.5 of the Nonhazardous Solid Waste Management Regulations apply.

Keep the waste determination, lab reports, MDEQ approvals, and the receiving site’s acceptance together. Record tonnage shipped, dates, and destinations. BUD holders report each year’s quantities and characterization to MDEQ by February 28.

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. Confirm a Category I standing use, or file or confirm the MDEQ BUD for that sand and use.
5. Get written acceptance and arrange pickup.

Common questions

Rules and guidance

• MDEQ: Mississippi Beneficial Use Program
• 11 Miss. Admin. Code Pt. 4, Ch. 9: Beneficial Use of Nonhazardous Solid Waste
• MDEQ: Request Form for a Beneficial Use Determination
• 11 Miss. Admin. Code Pt. 3, Ch. 1: Hazardous Waste Management Regulations
• 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