Foundry Sand Reuse in Maine

Planning to reuse spent foundry sand in Maine? This guide covers the rules that apply, the tests that decide how the sand can be managed, and what DEP 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. Maine calls this beneficial use. A solid waste separated for possible beneficial use is a secondary material. DEP licenses beneficial uses under Chapter 418.

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.

Maine’s beneficial use rule

Maine’s beneficial use rule is 06-096 C.M.R. ch. 418. Anyone proposing to beneficially use a secondary material, other than in agronomic utilization, must get a DEP license. Section 3 lists uses exempt from the rule. Chapter 400 defines beneficial use as using a solid waste or waste-derived product:

1. as a raw material substitute in manufacturing;
2. as construction material or construction fill;
3. as fuel; or
4. in agronomic utilization.

Every beneficial use must meet the general standards in Section 4. The use must serve a legitimate purpose and must not be disposal. The sand must work as an effective substitute for the raw material or product it replaces. Show this with comparable physical and chemical properties, relevant product or engineering specifications, and a use or market that is not speculative. The use must not pollute water or air, harm health, or create a nuisance. It must not include hazardous waste.

A generator does not always need its own license. When a processing, industrial, or manufacturing facility is licensed to use a secondary material for fuel, raw material substitution, or construction material, the generator supplying it needs no beneficial use license.

Some activities fall under other chapters. Placing waste in a landfill, including as alternative daily cover or grading material, is disposal under Chapter 401, not beneficial use. Storage longer than 90 days also falls under Chapter 402. Processing also falls under Chapter 409.

Maine’s general solid waste rule, 06-096 C.M.R. ch. 400, defines special waste to include “industrial and industrial process waste.” Special waste needs special handling, transport, and disposal procedures. Ask DEP whether it treats your spent sand as special waste before you plan storage and hauling.

Applying to DEP

• Who files: the generator, processor, facility, or other person proposing the beneficial use.
• Pre-application meeting: request one with DEP. At least 14 days before it, send a description of the sand and its use, its properties, Chapter 405 test results, quantities, and any risk management you are considering. You can skip the meeting if DEP already issued the generator a full license for that beneficial use.
• How: submit applications, revisions, and surrenders through MELS, DEP’s online licensing system.
• What to include: the waste characterization plan, lab results showing the sand is non-hazardous, and a showing that the use meets Section 4. Add a description of the facility and use, storage and handling, financial assurance, acceptance limits, quality control, and a draft Authorization Form. DEP may decide during pre-application review that some items are not needed.
• Risk standard: sand at or below the Appendix A screening levels meets the risk standard for those constituents. Above those levels, show that the use does not pose a significant risk to public health or the environment. Use a risk assessment, risk management, or both.
• Pilot projects: DEP may give temporary approval for a pilot or experimental project through a limited permit.
• After approval: licensed, ongoing beneficial uses file an annual report on DEP’s form. It covers quantities, sources, and test results.

Maine DEP, Augusta: (207) 287-7688.

Hazardous waste determination

Maine’s hazardous waste rules are 06-096 C.M.R. chapters 850–859. Chapter 850 incorporates the referenced federal hazardous waste regulations, as amended up to July 1, 2023, by reference. Where federal and Maine terms differ, the more stringent requirement applies.

Maine’s generator rules differ from the federal rules. Chapter 851 requires generators to keep determination records for at least 10 years. It also adds a very small quantity generator plus category. That generator makes less than 100 kilograms a month but holds over 55 gallons, up to 600 kilograms, at one time.

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.

Maine requires generators to keep determination records for at least 10 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, DEP, 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.

Chapter 405, Section 6(C)(2) lists the tests for wastes other than oily waste, ash, and paper mill or wastewater treatment sludge. They include a complete TCLP, total metals, chloride, percent carbon, moisture, pH, phosphorus, reactivity, and ignitability. DEP may add parameters based on the material and use.

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.

DEP licenses reuse case by case. Check any destination and proposed use with DEP before scheduling delivery.

When you talk to DEP, describe the proposal using Chapter 400’s categories. For example, is the sand a raw material substitute in manufacturing, or a construction material? Ask whether the receiving facility already holds a Chapter 418 license for this material and use. 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.

Maine State Plan covers state and local government workers in Maine. Federal OSHA covers private employers.

Storage and records

Store spent sand on a defined pad or in bins, control dust and runoff, and keep other foundry wastes out. Storage longer than 90 days also falls under Chapter 402. If DEP treats the sand as special waste, its transport and manifest rules also apply.

Keep the waste determination, lab reports, DEP licenses, and the receiving site’s acceptance together. Record tonnage shipped, dates, and destinations. When a license requires Authorization Forms, the generator gives one to each client and keeps a copy for 3 years. The person receiving the sand keeps its form for 3 years after the sand last arrives. For construction fill, a license may also require a deed notice, a deed restriction, or environmental monitoring.

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 Chapter 405 tests.
3. Choose a destination and get its material specifications.
4. Confirm the Chapter 418 license or exemption that covers that sand and use.
5. Get written acceptance and arrange pickup.

Common questions

Rules and guidance

• Maine DEP: Beneficial Use of Solid Wastes
• 06-096 C.M.R. ch. 418: Beneficial Use of Solid Wastes
• 06-096 C.M.R. ch. 400: General Provisions
• 06-096 C.M.R. ch. 405: Water Quality Monitoring, Leachate Monitoring, and Waste Characterization
• Maine DEP: Hazardous Waste
• 06-096 C.M.R. ch. 850: Identification of Hazardous Wastes
• 06-096 C.M.R. ch. 851: 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
• Maine State Plan