Foundry Sand Reuse in Arizona | Foundry Recycling Services

Planning to reuse spent foundry sand in Arizona? This guide covers the rules that apply, the tests that decide how the sand can be managed, and what ADEQ 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 Arizona, the route runs through the solid waste exemptions in state law. ADEQ’s director can grant more exemptions on petition.

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.

Arizona’s solid waste exemptions

Arizona’s solid waste definition and its exemptions are in A.R.S. § 49-701.01. Any person may petition the ADEQ director to exempt a substance from the definition of solid waste. The request may be statewide or for one site.

The director decides within 90 days of receiving the written request. The decision rests on a showing that the substance is unlikely to cause or substantially contribute to a threat to public health or the environment.

Site-specific exemption: takes effect on the date of the director’s decision. ADEQ publishes notice in the Arizona Administrative Register within 30 days.
Statewide exemption: ADEQ starts rulemaking within 30 days to add the substance to the exemption list. The exemption takes effect with the final rule.

The statewide exemptions adopted by rule are in Arizona Administrative Code R18-13, Article 2. They cover land-applied biosolids (R18-13-201) and coal slurry from pipeline leaks (R18-13-202).

The statute also exempts two other groups:

Inert material, defined in A.R.S. § 49-701. It must not be flammable, must not decompose, and must not leach above Arizona’s aquifer water quality standards. The definition lists concrete, asphaltic pavement, brick, rock, gravel, sand, and soil. It excludes special waste, hazardous waste, glass, and metal other than reinforcement in concrete.
Materials generated and reused on the same site. On-site reuse must be technically feasible. At least 75 percent of the material accumulated each year must be processed or reused that year. Manage stored material to control dispersion, discharges, vectors, fire hazards, and public access.

Petitioning ADEQ

Who files: any person may petition the ADEQ director.
How: send a written request to the director. Say whether you want a statewide or site-specific exemption.
What to show: that the substance is unlikely to cause or substantially contribute to a threat to public health or the environment.
Decision: the director decides within 90 days after receiving the request.
Scope: a site-specific exemption covers the named site. A statewide exemption applies only after rulemaking adds it to the exemption list.

ADEQ Solid Waste Section: compliance assistance (602) 771-4673, permits SolidWastePermits@azdeq.gov.

Hazardous waste determination

Arizona adopts the federal hazardous waste rules by reference in the Arizona Administrative Code, Title 18, Chapter 8. R18-8-261 incorporates 40 CFR Part 261, and R18-8-262 incorporates Part 262, each as revised July 1, 2020, with state changes.

Arizona adds generator duties in R18-8-262. Small and large quantity generators must keep a written log of storage-area inspections for three years. Generators get EPA identification numbers from ADEQ through its myDEQ portal.

Under 40 CFR 262.11, the foundry must decide whether its spent sand is hazardous:

Make the determination at the point of generation, before mixing or dilution. Repeat it if the waste may have changed.
Check whether the waste is excluded from the hazardous waste rules.
Check whether it matches a listed hazardous waste.
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, ADEQ, 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:

TCLP regulatory levels, RCRA metals
Contaminant	EPA waste code	Limit (mg/L)
Arsenic	D004	5.0
Barium	D005	100.0
Cadmium	D006	1.0
Chromium	D007	5.0
Lead	D008	5.0
Mercury	D009	0.2
Selenium	D010	1.0
Silver	D011	5.0

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.

To count as inert material, a material must not leach above Arizona’s aquifer water quality standards in a water leach test that approximates natural infiltrating water. For a petition, the data must show the sand is unlikely to threaten public health or the environment.

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.

ADEQ decides exemption petitions case by case. Check any destination and proposed use with ADEQ before scheduling delivery.

When you talk to ADEQ, name the route that fits: on-site reuse, inert material, or a petition for a site-specific or statewide exemption. 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.

Arizona Division of Occupational Safety and Health (ADOSH) runs Arizona’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. A site that stores solid waste generated there for 90 days or less is not a solid waste facility under A.R.S. § 49-701. For on-site reuse, process or reuse at least 75 percent of the accumulated material each year.

Keep the waste determination, lab reports, ADEQ decisions, and the receiving site’s acceptance together. Record tonnage shipped, dates, and destinations. Keep determination records for at least three years.

Before pickup

Identify the alloys cast, sand and binder systems, separate streams, monthly volume, and plant location.
Make the hazardous waste determination and complete the required tests.
Choose a destination and get its material specifications.
Confirm the exemption route with ADEQ, or file a written petition for that sand and use.
Get written acceptance and arrange pickup.

Common questions

Is a passing TCLP test enough?

No. It answers a toxicity question for the substances tested. The full waste determination, ADEQ’s decision, and the receiving site’s specifications still apply.

Does EPA’s risk assessment approve our sand?

No. It supports three soil-related uses for silica-based sand from iron, steel, and aluminum foundries. ADEQ still decides each exemption in Arizona.

Who can ask ADEQ for an exemption?

Any person may petition the director under A.R.S. § 49-701.01(C). The request must be in writing.

Can we use another foundry’s exemption?

Only if it covers your site and material. A site-specific exemption applies to that site. A statewide exemption applies once rulemaking adds it to the exemption list.

How long can spent sand stay at the plant?

A site that stores its own solid waste for 90 days or less is not a solid waste facility. For on-site reuse, process or reuse at least 75 percent of the accumulated material each year.

How fast does ADEQ decide a petition?

The director decides within 90 days after receiving the written request.