Foundry Sand Reuse in North Dakota

Planning to reuse spent foundry sand in North Dakota? 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. North Dakota’s rules call this “beneficial use” and authorize it through DEQ general permits for categories of waste 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.

North Dakota’s beneficial use rule

North Dakota defines beneficial use in NDAC 33.1-20-01.1-03. It is use of a solid waste in a manufacturing process to make a product, or as a substitute for a raw material or product, without harm to health or the environment. The use must:

1. provide a functional benefit;
2. substitute for a virgin material; and
3. meet relevant product specifications, regulatory standards, or design standards. Where none exist, the material may not be used in excess quantities.

The beneficial use rule is NDAC 33.1-20-02.1-03. DEQ may issue general permits, regional or statewide, for a category of beneficial use. The wastes must come from the same or similar operations and have similar physical and chemical makeup. Using the waste as an ingredient or product substitute may not present more harm than the material it replaces.

You do not need an individual solid waste permit if you follow an applicable general permit and register when it requires registration. DEQ may still require an individual permit when a person does not comply or the activity may cause harm.

DEQ may also approve a solid waste pilot project under NDAC 33.1-20-02.1-10. Get written approval before you start. A pilot project may not last more than two years.

Applying to DEQ

• Who files: any person may apply for a new general permit. DEQ may also issue one on its own.
• How: apply on a DEQ form and pay the fee in NDAC chapter 33.1-20-15.
• Contents: describe the sand, with enough sample analyses to show its range of physical and chemical properties. Describe the proposed use and the process that makes the sand, with a diagram.
• Limits: propose contaminant concentration limits and explain why they are protective.
• Suitability: show the sand helps the use and meets the standards for the material it replaces. Roadway uses need Department of Transportation approval, if applicable.
• Land placement: construction material, soil substitute, soil additive, and other land uses need an evaluation of health and environmental impacts. Cover exposure through groundwater, surface water, air, and the food chain.
• Blends: if the sand is blended with other wastes, show each one adds to the use. State the quantities and proportions, and keep the blend consistent.
• Review: DEQ posts notice once the application is substantially complete. It follows the same review and public notice procedures as for individual permits.
• Coverage: a general permit may require registration or an application, including site approval, before you start.
• Term: each general permit has a fixed term of no more than ten years.
• After approval: DEQ may modify, suspend, revoke, or reissue a general permit or coverage under it to prevent harm.

DEQ Division of Waste Management: 701-328-5166, solidwaste@nd.gov.

Hazardous waste determination

North Dakota’s hazardous waste rules are in NDAC Article 33.1-24. The toxicity characteristic is NDAC 33.1-24-02-14.

Two state rules stand out. Waste testing for the determination must be done by a laboratory approved under DEQ’s certification procedures. A generator needs an identification number and a DEQ registration certificate before it stores, ships, or disposes of hazardous waste.

Under NDAC 33.1-24-03-02, 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.

North Dakota requires generators to keep determination records for at least 3 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, 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.

A general permit sets limits on the physical and chemical properties of waste it covers, including leachability. It may also require periodic waste analyses.

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

When you talk to DEQ, describe the proposal in the rule’s terms. 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. Sand used under a general permit must stay within the permit’s physical and chemical limits. Tell DEQ right away if its properties change, including leachability.

Keep the waste determination, lab reports, DEQ approvals, and the receiving site’s acceptance together. Record tonnage shipped, dates, and destinations. Report other changes, such as owners or generators, within the time the permit sets, or 30 days if it sets none. 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. Confirm DEQ coverage for that sand and use, under a general permit, an individual permit, or a pilot project.
5. Get written acceptance and arrange pickup.

Common questions

Rules and guidance

• NDAC 33.1-20-02.1: Permit Provisions and Procedures (general permits for beneficial use)
• NDAC 33.1-20-01.1: Solid Waste General Provisions (definitions)
• DEQ Guideline 38: Beneficial Use of Inert Waste
• NDAC 33.1-24-02: Identification and Listing of Hazardous Waste
• NDAC 33.1-24-03: Standards for Generators
• 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