Treated Wood Disposal and the Never-Burn Rule

Why this matters

Every deck, fence, raised bed and porch skirt you tear out is treated lumber, and almost all of it goes to the landfill with no fuss. The trouble is the one thing customers love to do with old deck boards: burn them in the firepit. Burning the older arsenic-treated wood turns a material that sits fairly stable in a landfill into smoke and ash that carry the arsenic out to where people breathe it and children dig in it. The crew that leaves a stack "for the firepit" has done the one harmful thing in the whole job, and done it as a favor.

The two generations of treated lumber

CCA (chromated copper arsenate) was the standard residential wood preservative for decades. Under a voluntary agreement between the manufacturers and EPA, CCA treatment for most residential uses (decks, play structures, fencing, picnic tables, landscape timbers) ended at the close of 2003. It is still made for some industrial and agricultural uses such as utility poles, highway posts and some marine pilings. So anything built for a house before about 2004 is presumptively CCA, and anything built since is presumptively not, unless it came from old stock or a salvage pile.

The current generation is copper-based without arsenic or chromium: ACQ (alkaline copper quaternary), copper azole, and micronized-copper versions of both. These are less toxic, but they are still not wood you burn, compost or chip into mulch. The copper concentrates in the ash, and the open-burning rules that ban CCA almost always ban these too.

Other treatments you meet on outdoor jobs are creosote (railroad ties and old pilings: black, oily, a strong tar smell) and pentachlorophenol (utility poles). Some states regulate those wastes more tightly than deck lumber, and landfills often take them only by prior arrangement. Treat a creosote tie as its own waste stream, never as part of the deck load.

Telling CCA from the newer wood

You cannot reliably tell by eye, so give it one quick look and then stop trying. The cues that point to CCA:

• Age of the structure. Built before 2004, from permit records, the customer's memory of when it went in, or the house's own history.
• Color. Weathered CCA goes silver-gray with a faint green cast in the checks; new ACQ is a brighter green-brown that also weathers gray. The colors overlap too much to decide on.
• Tags and stamps. End tags or ink stamps name the preservative and its retention level. On a 25-year-old deck they are usually gone, and cut ends never had them.
• Testing. Arsenic swab kits exist, and a lab or an XRF (X-ray fluorescence) reading is definitive. Worth it only when the answer changes what you do, which outside a state with special rules it rarely does.

The working rule: any treated wood of unknown age is handled as CCA. In most states that costs nothing on disposal, because both generations go to the same landfill, and it gets the dust and burning controls right by default.

Disposal: the federal floor and the state layer

Federal layer. Under RCRA, discarded arsenical-treated wood generated by the people who used it for its intended end use is excluded from the definition of hazardous waste, even where it would fail the toxicity test for arsenic, provided it is not hazardous for some other reason (40 CFR 261.4(b)(9)). A deck coming off a house is exactly that case, so at the federal level it can go to a municipal solid waste landfill or a construction and demolition (C&D) landfill with the rest of the job debris. Where you have the choice, a lined municipal landfill is the better destination: unlined C&D landfills have been studied for arsenic leaching into groundwater, which is why some states steer treated wood into lined cells.

State layer, which routinely overrides. California is the clearest case. It regulates treated wood waste under its own management standards, which restrict where the waste can go (facilities approved to take it, not any C&D site), require it be kept separate from other debris, and limit how and how long it is stored before it moves. A handful of other states have their own rules or landfill acceptance limits, and many add nothing beyond the federal exclusion. Check your state environmental agency's treated-wood guidance, and then ask the landfill or transfer station directly, because their acceptance rules are the ones that turn your truck around at the scale.

What it never is: free fill, mulch, compost, or a gift. Chipping treated wood into landscape cover is prohibited in many states and wrong everywhere. Handing the boards to a neighbor for a chicken coop or a vegetable bed puts the arsenic back in contact with skin, soil and food. Reusing sound treated lumber in the same kind of application (a fence rail, a shed ramp) is a judgment call; reusing it where people grow food or children play is not.

Why burning is the line you do not cross

In a landfill, most of CCA's arsenic stays bound in the wood. In a fire the wood is consumed, part of the arsenic leaves in the smoke as fine particles, and the rest concentrates in the ash. That mechanism is behind every agency warning. EPA's guidance, and that of every state agency that publishes on treated wood, says the same thing: never burn it in an open fire, wood stove, fireplace, firepit or residential boiler. Many states prohibit it outright through their open-burning rules regardless of which preservative it carries, and air districts that allow backyard fires almost always exclude treated, painted or stained lumber.

The ash is the part people forget. A small fire of old deck boards leaves a pile of ash that someone shovels onto a garden bed, or that a dog and a toddler walk through. The smoke route is inhalation; the ash route is ingestion and skin contact. A homeowner applies no control to either.

The newer copper treatments are not a loophole. Open-burning rules ban them in most places, and nobody has made the case that their smoke is benign.

The firepit conversation

The customer is not being reckless; they think it is firewood. Get ahead of it at the estimate rather than at the curb. One plain sentence in the walkthrough does it: "The old boards are treated lumber, and the older stuff has arsenic in it, so it can't be burned. We haul all of it." Put the treated wood on the estimate as its own haul-away line so the customer knows it is leaving with you (see related: Writing the Haul-Away and Disposal Line in an Estimate).

If the customer still wants to keep the boards, the material is theirs until agreed otherwise (see related: Who Owns the Old Equipment You Remove), and you cannot make them give it up. What you can do is tell them why, note on the job that you told them and that they kept it, and not stack it beside their firepit yourself. A crew that carries it there has helped.

Cutting and handling: the dust route

Demolition makes sawdust, and CCA sawdust carries the same arsenic. Each control belongs to the act that makes the dust:

• Unscrew or pry before you cut. Backing out fasteners and lifting boards whole makes almost no dust; a circular saw or reciprocating saw through a joist makes a lot. Cut only where removal or fitting the container requires it.
• Cut outdoors, with the crew upwind, never in a garage or crawlspace, and away from open windows.
• Respiratory protection for the cutting. A filtering facepiece respirator is the common choice for short outdoor cuts. Where the shop requires respirators, that means a written program with medical evaluation and fit testing under 29 CFR 1910.134; where wearing one is voluntary, the wearer still gets the information in Appendix D of that standard. Eye protection and gloves for the dust and splinters.
• Hygiene, because ingestion is the main route. Wash hands before eating, drinking or smoking; arsenic gets into people from dusty hands more than from anything else. Brush off clothing outdoors, and sweep up sawdust with the debris rather than leaving it in the lawn or a sandbox.
• Do not sand or pressure-wash old CCA to "freshen it up" before a demolition is decided; that is a dustier, wetter exposure than the demo itself.

Worked example: a 1998 deck coming off a house

A crew is removing a 12 by 16 ft deck built in 1998, with a rail on three sides and one set of stairs. No tags survive. The house is in a state with no treated-wood rules beyond the federal exclusion, and the regional landfill takes treated wood as ordinary C&D debris.

Classification. Built five years before the 2003 phase-out, preservative unknown: handled as CCA. No test, because a test result would not change the destination.

Material. About 25 decking boards 16 ft long, 13 joists 12 ft long, a doubled rim, four posts, the rail system and two stair stringers. The estimate called for one 10-yard roll-off for the deck plus the gravel and paver base underneath, with a separate line naming the treated lumber and its landfill destination.

The fork, twice. At the walkthrough the customer asked to keep "the good boards" for winter fires. The tech said the sentence above, the customer agreed, and the line stayed on the estimate. On demo day the customer's adult son, who had not been at the walkthrough, asked the crew to leave a stack by the firepit. The lead declined, explained why, and noted both conversations on the job.

Dust. Decking unscrewed and lifted whole. Joists cut into 6 ft lengths to fit the container, outdoors, on the far side of the yard from the kitchen windows, crew in respirators and eye protection. The sawdust went into the roll-off with the last of the debris rather than into the grass, because a vegetable bed sits eight feet from the stairs.

What changes the answer. Move the same deck to California and three things change: the treated wood has to come out of the mixed roll-off and be kept separate from the paver base, it has to go to a facility approved for treated wood waste, and the shop has to meet the state's storage and paperwork standards for it, all settled before the container is ordered. In a state where the landfill accepts treated wood only into a lined cell, the hauler may run it as a separate load at its own rate. In every case the change is to destination and separation, never to the burning rule, which holds everywhere.

Failure mode. The usual failure is not at the landfill. It is the stack left by the firepit, or the joist offcuts dropped into the customer's yard-waste cart, which goes to a composting facility that rejects contaminated loads and can trace one back to the address.

Verifying you got it right

• The estimate named the treated wood and where it was going.
• No treated wood stayed on site unless the customer kept it after being told, and the job notes record that conversation.
• The landfill or transfer station ticket is attached to the job.
• In a state with treated-wood rules, the separation and destination matched that state's standard, confirmed when the container was ordered rather than discovered when it was full.

References

• 40 CFR 261.4(b)(9), exclusion of arsenical-treated wood from the definition of hazardous waste when discarded by the end user.
• EPA, chromated copper arsenate (CCA) information, including the 2003 voluntary residential phase-out and the guidance never to burn treated wood.
• 29 CFR 1910.134, respiratory protection, including Appendix D on voluntary use.
• California Department of Toxic Substances Control, treated wood waste management standards.
• See related: Construction and Demolition Debris: What Goes Where.