Foundry Sand Reuse in Delaware

Planning to reuse spent foundry sand in Delaware? This guide covers the rules that apply, the tests that decide how the sand can be managed, and what DNREC 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 Delaware, recycling and reuse operations need written DNREC approval. Delaware calls this approval a beneficial use determination (BUD).

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.

Delaware’s recycling permit rule

Delaware’s rule is 7 DE Admin. Code 1301, the Regulations Governing Solid Waste. It has no provision written for foundry sand. Under Section 2.5.2, recycling solid waste into specific market applications requires a DNREC permit before the work starts. The application must include:

1. a written plan of operation that describes the types and quantities of materials accepted, the processing methods and equipment, and the products made; and
2. documentation that a market exists for the products.

A BUD is typically for recyclers that handle segregated materials. More complex operations that handle mixed wastes need a Resource Recovery Facility Permit under Sections 4.4 and 9.0.

The rule does not apply to waste that meets the criteria of hazardous waste (Section 2.2.4). Sand that is hazardous follows Delaware’s hazardous waste rules instead.

Stockpiles have limits. A recycling permit application states the most feedstock and product the site will store at one time. At a resource recovery facility, nonputrescible recyclables may be stored up to 30 days unless DNREC approves longer in writing (Section 9.4.2.2.4).

Applying to DNREC

• Who files: the operation that will recycle or reuse the sand. The application names the facility, its owner, and its operator.
• How: complete DNREC’s Recycling Permit Application and the Recycling and Composting Permit Checklist. Submit three copies of the full package and an electronic PDF copy to the Compliance and Permitting Section.
• Content: include proof of ownership or a lease, written zoning approval, and a plan of operation with a site map, equipment, process, and maximum stockpile amounts. Add evidence that the product use will not harm human health or the environment, and buyer contracts or letters of intent.
• Closure and other permits: include a conceptual closure plan, financial assurance for closure, proof of other required permits, and a background statement under 7 Del. C. Chapter 79.
• Completeness: DNREC will not process an application that is missing any checklist item.
• Renewal: apply to renew at least 180 days before a permit expires (Section 4.1.6).
• Hauling: anyone transporting solid or hazardous waste in, out, or through Delaware needs a DNREC waste transporter permit first. Subcontractors need their own permit.
• Liquids and sludge: wastes covered by Division of Water rules are not regulated as solid waste under 7 DE Admin. Code 1301 (Section 2.2.3).

DNREC Compliance and Permitting Section: (302) 739-9403, 89 Kings Highway, Dover, DE 19901.

Hazardous waste determination

Delaware writes the federal hazardous waste rules into its own Regulations Governing Hazardous Waste, 7 DE Admin. Code 1302. Part 260 lists Parts 260–266, 268, 273, 279, 122, and 124.

Delaware’s reporting is stricter. A generator that is a large quantity generator in any month must file a hazardous waste report by March 1 of the next year (Section 262.41). The federal rule requires this report every other year.

Under 7 DE Admin. Code 1302, § 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, DNREC, 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 recycling permit application must show that the product use will not harm human health or the environment. DNREC’s checklist says that may require analyses and other tests.

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.

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

When you talk to DNREC, describe the proposal in the terms of Section 2.5.2. What market application will use the sand, and what product will it make? Confirm that the receiving site’s DNREC permit or BUD covers spent foundry 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. Keep stored amounts within the maximums in the receiving site’s permit. At a resource recovery facility, plan shipments so recyclables leave within 30 days unless DNREC approves longer in writing.

Keep the waste determination, lab reports, DNREC 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 DNREC recycling permit or BUD that covers this sand and use.
5. Get written acceptance and arrange pickup with a DNREC-permitted waste transporter.

Common questions

Rules and guidance

• DNREC: Solid Waste Facilities
• Delaware Business First Steps: Recyclers, Reuse, and Composting Operations
• DNREC: Recycling Permit Application
• DNREC: Recycling and Composting Permit Checklist
• 7 DE Admin. Code 1301: Regulations Governing Solid Waste
• 7 DE Admin. Code 1302, Part 260: Hazardous Waste Management System, General
• 7 DE Admin. Code 1302, Part 262: Standards Applicable to Generators of Hazardous Waste
• DNREC: Hazardous Waste
• DNREC: Solid and Hazardous Waste Transporter Permits
• 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