Foundry Sand Reuse in Maryland

Planning to reuse spent foundry sand in Maryland? This guide covers the rules that apply, the tests that decide how the sand can be managed, and what to bring to MDE 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. Maryland’s law calls this recycling: returning recyclable materials to the marketplace as raw materials or products. MDE’s Solid Waste Program oversees non-hazardous industrial solid waste.

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.

Maryland’s solid waste and recycling rules

Maryland’s solid waste definitions are in Environment Article §9-101. Solid waste means any garbage, refuse, sludge, or liquid from industrial, commercial, mining, or agricultural operations or from community activities.

Recycling returns recyclable materials to the marketplace as raw materials or products (§9-1701). Recyclable materials would otherwise become solid waste for disposal. They count as solid waste unless they return to the marketplace as a raw material or product within one calendar year of receipt. Material managed under recycling facility rules adopted under §9-1713 is also not solid waste.

Receiving sites may need a permit. A refuse disposal system for public use needs an MDE permit before it is installed, materially altered, or materially extended. So does a solid waste acceptance facility (§9-204). COMAR 26.04.07.04C lists the exceptions to the landfill permit requirement.

Bring each reuse proposal to MDE’s Solid Waste Program before you ship.

Working with MDE

• Who to contact: MDE’s Solid Waste Program, in the Land and Materials Administration.
• What to describe: the alloys cast, sand and binder systems, test results, monthly volume, receiving site, and proposed use.
• Receiving site: ask for its MDE Refuse Disposal Permit, or for the rule that lets it operate without one.
• Liquids and sludge: Maryland’s solid waste definition includes sludge and liquid from industrial operations. Describe any wet streams separately.
• Hazardous waste questions: MDE’s Hazardous Waste Program regulates hazardous waste in Maryland.

MDE Land and Materials Administration: 1800 Washington Boulevard, Baltimore, MD 21230.

Hazardous waste determination

Maryland’s hazardous waste rules are in COMAR 26.13. COMAR 26.13.01.05 incorporates selected federal rules by reference. Most requirements are written into the state rules.

Maryland’s small quantity exemption covers generators of less than 100 kilograms of hazardous waste a month. If more than 100 kilograms accumulates on site at any time, that waste becomes fully regulated (COMAR 26.13.02.05).

Under COMAR 26.13.03.02, 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. Test when knowledge alone is not enough.

Maryland 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, MDE, 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.

Maryland applies these TCLP limits in COMAR 26.13.02.14.

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.

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

When you talk to MDE, describe the proposal in the terms of §9-1701. For example, does the sand return to the marketplace as a raw material, such as a concrete ingredient, or as a product? Get the receiving site’s specifications, permit status, 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.

Maryland Occupational Safety and Health (MOSH) runs Maryland’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. Plan volumes so recyclable sand returns to the marketplace within one calendar year of receipt. Material held longer counts as solid waste under Environment Article §9-101(j).

Keep the waste determination, lab reports, MDE correspondence, and the receiving site’s acceptance together. Record tonnage shipped, dates, and destinations.

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 and permit status.
4. Check the sand and proposed use with MDE’s Solid Waste Program.
5. Get written acceptance and arrange pickup.

Common questions

Rules and guidance

• MDE: Solid Waste Management in Maryland
• Environment Article §9-101: Definitions
• Environment Article §9-1701: Recycling definitions
• Environment Article §9-204: Refuse disposal permits
• COMAR 26.04.07.04: Sanitary landfill permits and exceptions
• COMAR 26.13.01.05: Hazardous waste incorporation by reference
• COMAR 26.13.02.05: Small quantity generators
• COMAR 26.13.02.14: Toxicity characteristic
• 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
• Maryland Occupational Safety and Health (MOSH)