Two documents come up when a California facility closes a site that handled hazardous materials: a closure plan and a closure report. They sound similar. They are not. One is the blueprint you submit before closure activities can begin. The other is the record you submit after the work is done. Mixing them up is a common reason closures stall or get re-opened 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).

This piece sits inside our wider facility changes guide. If you are new to the topic, start with California facility closure plans and how the process works. Here we focus on the difference between the two documents, when each is required, and what California regulators expect to see in each.

The Short Version

The plan is the permit to act. The report is the proof of what was done.

Side-by-Side Comparison

Why the Timing Rule Matters

The 30-day advance notice that most CUPAs expect is the single most common timing trap. Industry presenters at the 2026 California CUPA Conference flagged inadequate notification as the top pitfall in facility decommissioning, with 30 days as the typical floor. Some CUPAs ask for more. Some want a pre-closure walkthrough on top of the written notice.

That timing has practical consequences:

• Decontamination work the CUPA has not approved can be set aside and required to be redone under the approved plan.
• If the landlord has set a hard vacate date, the 30-day clock has to be built backwards from the date the agency needs to inspect, not from the date you want to be out.

When we walk a facility for the first time on a closure, the first question is not what to clean. It is what date the CUPA needs the plan in hand so the rest of the schedule can be built around it.

What Belongs in Each Document

A closure plan is forward-looking. The agency wants to see that you understand what is on the site and that the methods are appropriate for it. The plan covers:

• The current chemical inventory and any “special items” that change scope: radiation sources, underground storage tanks, perchloric acid hoods, azides, mercury use, prior releases.
• A sampling and analysis plan naming the contaminants of concern, sample types (wipe, chip, core), chain-of-custody protocol, accredited lab, and the acceptance criteria agreed on with the agency.
• A health and safety plan for the closure crew.
• A site map showing where each activity happens.

For a section-by-section walkthrough, see what goes into a facility closure plan.

The report is where the plan gets tested against reality. Inspectors look for matched pairs: every procedure in the plan should have an entry in the report saying what was done, what waste was generated, where it went, and which samples confirmed the area was clean. Specifically, the report records:

• Closure procedures performed in each area, including the decontamination method and personnel involved.
• The sampling and analysis summary with locations, dates, results, and interpretation against the acceptance criteria.
• Every hazardous waste manifest that left the site during closure.
• Lab reports as appendices.
• Certifications, including a PE stamp where the closure involves a permitted treatment unit or where the agency requires one.

For permitted treatment unit closures (Conditionally Authorized, Permit-by-Rule, and similar DTSC-administered tiers), the closure report is the document the PE signs to certify that the unit was closed in compliance with Title 22 and DTSC requirements.

What Goes Wrong at the Review Stage

Agency review patterns we see often:

• A plan that is too generic gets returned for rework. A copy-paste from a prior facility, without the current site’s actual chemical inventory and layout, is the fastest way to add 30 days to your schedule.
• A report without verification sampling results is incomplete. “We cleaned everything” is not a closure record. The lab data is the record.
• A report that does not match the approved plan triggers follow-up. If the plan said wipe sampling and the report has only visual inspection, expect to be asked why.

For more on agency expectations during closure, see what CUPA looks for at facility closure.

Landlord and Buyer Audiences

The CUPA is the regulator. The landlord or buyer is the audience that often drives documentation. Landlords typically want the full closure report, the lab data, and the agency sign-off letter before accepting the space back. Plan one report that satisfies both audiences: the agency’s standard and the landlord’s stricter one.

Working With CDMS

We write the plan, run it through the CUPA, manage the field work, do the verification sampling, and assemble the closure report under one team. One schedule, one set of documents that match each other. When the closure involves a permitted treatment unit, we deliver the report with the professional engineer certification the regulation requires.

Closing a permitted treatment unit? How tiered permit closure certification works →