Foundry Sand Reuse in Hawaii

Planning to reuse spent foundry sand in Hawaii? This guide covers the rules that apply, the tests that decide how the sand can be managed, and what DOH 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 Hawaii, DOH reviews proposed reuse through its solid waste facility permits. Hawaii’s rule defines “industrial solid waste” to include nonhazardous waste from foundries.

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.

Hawaii’s solid waste permit rule

Hawaii’s solid waste rule is HAR chapter 11-58.1, Solid Waste Management Control. It has no separate beneficial use approval and no provision written for foundry sand. DOH works through facility permits and a few exemptions:

1. A facility that manages solid waste needs a DOH permit to be established, modified, or operated (HAR 11-58.1-104).
2. Some operations are exempt from the permit, including minor sources as determined by DOH. They must notify DOH in writing at least 30 days before starting (HAR 11-58.1-102(c) and 11-58.1-124(b)).
3. A permitted processing or storage facility may accept industrial waste only with DOH’s specific approval (HAR 11-58.1-123(c)).

The rule defines industrial solid waste as nonhazardous solid waste from manufacturing or industrial processes. Its list of examples includes nonferrous metals manufacturing or foundries, and iron and steel manufacturing.

The owner, operator, and occupant of the property where solid waste builds up must remove it to a permitted facility. A contract for removal does not shift that duty (HAR 11-58.1-106).

Applying to DOH

• Who files: the owner and operator of the facility that will manage the sand. Both sign the permit application. A corporation files through an officer, the facility’s general manager, or an authorized representative.
• How: complete DOH’s application form and the attachments for the facility type. Include the filing fee.
• Timing: submit the package at least 180 days before the planned start or change, or 180 days before an existing permit expires.
• Market evaluation: describe the end use, show that the finished product protects human health and the environment, and evaluate available markets. Include a plan to dispose of product that cannot be sold (HAR 11-58.1-122).
• Sampling: DOH may require site access and sampling data to judge the degree of pollution from the facility (HAR 11-58.1-104(c)(2)).
• Fees: set by HAR 11-58.1-104(i). A recycling processing facility or a storage facility pays $250. Fees are not refunded.
• After approval: a permit lasts up to five years and can be renewed. It cannot be transferred without DOH’s written approval. DOH may modify, suspend, or revoke a permit after offering a hearing.
• Exempt operations: notify DOH in writing at least 30 days before starting. Include a site plan, an operations narrative, the owner’s approval, and proof of zoning compliance.

DOH Solid Waste Section: (808) 586-4226.

Hazardous waste determination

Hawaii adopts the federal hazardous waste rules by reference, with state amendments, in HAR chapters 11-260.1 to 11-279.1. The rules in effect since July 7, 2025, adopt the federal text as amended July 1, 2024.

One Hawaii change matters if hazardous sand is stored on site. Small and large quantity generators must record each weekly inspection of central accumulation areas in a log. The log shows the date, time, inspector, observations, and any repairs. Keep it for at least three years (HAR 11-262.1-3).

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, DOH, 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 facility permit, DOH may require sampling data and site access (HAR 11-58.1-104(c)(2)).

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.

DOH decides reuse case by case through facility permits. Check any destination and proposed use with DOH before scheduling delivery.

Confirm the receiving site holds a DOH permit or exemption, and DOH’s specific approval to accept industrial waste. When you talk to DOH, describe the end use and how the product protects health and the environment. Explain what happens to material that cannot be used. 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.

Hawaii Occupational Safety and Health Division (HIOSH) runs Hawaii’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. Remove accumulated solid waste to a permitted facility before it creates a nuisance or a health or safety hazard (HAR 11-58.1-106).

Keep the waste determination, lab reports, DOH 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. Confirm the destination holds a DOH permit or exemption and approval to accept this industrial waste.
5. Get written acceptance and arrange pickup.

Common questions

Rules and guidance

• Hawaii DOH: Solid Waste Permits
• HAR chapter 11-58.1: Solid Waste Management Control
• Hawaii DOH: Solid waste facility permit instructions
• Hawaii DOH: Hazardous waste rules, HAR 11-260.1 to 11-279.1
• HAR chapter 11-262.1: 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
• Hawaii Occupational Safety and Health Division (HIOSH)