Facility Closure vs. Unit Closure: Which One Applies to You?
When a California facility tells us they need to “close something out,” they almost always mean one of two very different things. Either the whole site is shutting down or moving, or a single piece of permitted equipment is being retired while the rest of the operation keeps running.
When a California facility tells us they need to “close something out,” they almost always mean one of two very different things. Either the whole site is shutting down or moving, or a single piece of permitted equipment is being retired while the rest of the operation keeps running. These two situations follow different regulations, involve different agencies, and produce different deliverables. Picking the wrong path costs time and creates compliance gaps later.
This piece walks through the difference, who enforces each one, and how to tell which one your situation requires. For a broader view of how openings, transfers, and closures fit together, see our facility changes in California guide.
The Short Version
A facility closure is what you need when the entire site is closing or relocating. It is administered by your local CUPA (Certified Unified Program Agency, which may be a county environmental health department, fire department, or another local agency depending on jurisdiction), and the deliverable is a Closure Plan submitted before closure, followed by a Closure Report after the work is done.
A unit closure, formally a Tiered Permit Unit Closure Certification, is what you need when a single hazardous waste treatment unit (a tank, a containment area, a treatment system operating under Conditionally Authorized, Permit by Rule, or a similar tier) is being decommissioned while the facility continues to operate. It is administered by DTSC, the California Department of Toxic Substances Control, and the deliverable is a PE-stamped closure certification for that unit (for PBR closures).
Side-by-Side Comparison
| Facility Closure | Unit (Tiered Permit) Closure | |
|---|---|---|
| What’s closing | The entire facility (relocation, shutdown, sale of the site) | One permitted hazardous waste treatment unit; the facility keeps operating |
| Lead agency | Local CUPA | DTSC |
| Trigger event | Lease ending, move-out, ownership-driven shutdown, end of operations | Process change, equipment replacement, downsizing, DTSC or CUPA inquiry on an inactive unit |
| Primary regulation | Hazardous Materials Business Plan rules under California Health & Safety Code Chapter 6.95; CUPA closure requirements | California Code of Regulations, Title 22, Division 4.5 (Tiered Permitting closure requirements) |
| Core deliverables | Closure Plan (pre-closure), then Closure Report (post-closure), with sampling plan, decontamination procedures, and agency coordination | PE-stamped Closure Certification (PBR), Closure Cost Estimate, and (above the $10,000 threshold, PBR/CA tiers) financial assurance documentation |
| PE stamp | Often required, depending on scope | Required by DTSC for PBR closures; CA/CE tiers have different requirements |
| Notification rule | Coordinate with the CUPA well in advance; the plan is typically submitted in advance of closure activities so the agency can review and approve | Notify DTSC at least 15 days before completion of closure |
| Typical timeline | Several months minimum from notice through agency sign-off | Shorter; driven by site visit, documentation review, and PE turnaround |
| What it does NOT cover | Permit-by-permit closures (air, EPA ID, stormwater, wastewater) are quoted and handled separately | Full-site closure activities, building decontamination, broad sampling plans |
When You Need a Facility Closure
If the entire site is going away (the lease is ending, the company is moving, the operation is shutting down), your CUPA will expect a facility-level Closure Plan. The plan describes the facility, the hazardous materials that have been on site, how the closure will be carried out, the sampling that will verify the site is clean, and the schedule.
Once the CUPA reviews and approves the plan, closure activities begin: removal of remaining hazardous materials, decontamination of equipment and building areas, hazardous waste disposal, and post-decontamination sampling. After the work is complete, a Closure Report documents what was done, with lab results and waste manifests.
The most common misunderstanding we see at this stage is scope. A Closure Plan does not automatically close out your other permits. Air permits, stormwater coverage, wastewater discharge permits, your EPA ID, and any tiered permit you hold are separate closure actions, each handled with the issuing agency. When we walk a facility for closure, the first thing we map is the full list of active permits so nothing gets left open after the doors close.
When You Need a Unit Closure
A unit closure applies when one piece of permitted treatment equipment is coming out of service and the rest of the facility keeps running. The most common drivers we see are equipment replacement, a process change that removes the need for on-site treatment, and downsizing that takes a unit out of operation.
This is a DTSC-side action under California’s Tiered Permitting program. The unit has to be properly decontaminated, the closure has to be documented, and for PBR closures, a California-registered Professional Engineer has to certify that the unit was closed in accordance with the requirements that apply to its tier (Conditionally Authorized, Permit by Rule, or the relevant authorization for your unit).
Two California-specific items matter here. First, DTSC requires notification at least 15 days before closure is complete. Second, for PBR and CA tiers, if the total closure cost estimate is above $10,000, financial assurance documentation is required as part of the closure package; below that threshold, the cost estimate is still required, but a financial assurance mechanism is not. CE units do not have a closure financial-assurance requirement.
A unit closure is a narrower scope than a facility closure. It does not include full-site decontamination, multi-area sampling, or the broader CUPA-led closure process. If decontamination of the unit is still pending when the project starts, that work has to be added to scope; the certification confirms the unit was properly closed, which assumes the cleanup is already complete or part of the project.
How to Tell Which One Applies
Three questions usually settle it.
Is the entire facility closing, or just one unit?
If the whole site is going away, you need a facility closure. If operations continue and only a treatment unit is being retired, you are in unit-closure territory.
Who has been asking about it?
A request from the CUPA points to facility closure. A request from DTSC, or a tiered permit issue surfaced during a renewal or audit, points to unit closure.
What’s the long-term plan for the building?
If the building is being vacated, sold, or repurposed for a non-regulated tenant, the CUPA needs a facility closure on file. If you are keeping the building and just changing what happens inside it, the question is which units inside are still operating.
There is one situation where both apply at once: a facility closing entirely that also has tiered permit treatment units operating at the time of closure. In that case, each unit needs a closure certification as part of the broader facility closure, and the two scopes run together. We have seen facilities try to handle just one side of that without addressing the other, and the loose end almost always shows up later as a DTSC follow-up or a CUPA finding when the next tenant tries to start a regulated operation in the same space.
Picking the Right Scope From the Start
The cost of guessing wrong is bigger than the cost of scoping it correctly the first time. A facility closure scoped as a unit closure leaves permits open and the CUPA without a plan it expects to see. A unit closure scoped as a facility closure layers on work and agency coordination that DTSC does not require for the smaller action. Both produce the same outcome: rework, delays, and an agency relationship that takes longer to settle.
Closing just one treatment unit? Tiered permit closure certification in California →
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BSY started working with CDMS last year after our in-house EHS person departed the company. CDMS reviewed our existing operational permits as well as any additional Federal, State and Local regulations that could apply and helped us to create a comprehensive compliance calendar to track regulatory deadlines and submittal due dates. The CDMS team does an excellent job of tracking everything and can be relied upon to complete the forms accurately and assist with submittals, allowing me to focus on our business.
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