Post-spill sampling is how you prove a site is clean enough to close, and how you defend that conclusion if a regulator questions it. After a release of crude, condensate, or produced water, the difference between a managed, defensible event and an open-ended liability is a documented, data-driven process: contain, characterize, remediate, and verify. This is a five-step protocol for characterizing and closing a spill site in line with RRC and EPA guidance, with the sampling and laboratory work that makes closure stick.
Step 1: Contain the spill and report it
The first response is physical containment and prompt notification. Use sorbent materials and booms to halt migration, especially toward surface water. Then determine whether the release meets a reporting threshold, which for oil and gas operators can trigger notification to the RRC district office and, when water is involved, the National Response Center. That first report starts the formal regulatory record and establishes timely, responsible action. The full reporting detail is in our guide to reporting a spill to the RRC and EPA; the core triggers are below.
| Substance | Reporting trigger | Primary agency | Key regulation |
|---|---|---|---|
| Crude oil / condensate (to land) | More than 5 barrels | RRC District Office | Statewide Rule 20 (16 TAC 3.20) |
| Produced water / brine (to land) | No codified land threshold; report if it reaches water | RRC District Office / TCEQ | Statewide Rule 20 (16 TAC 3.20) |
| Oil / hazardous substance (to water) | Any amount causing a sheen | National Response Center (NRC) | Clean Water Act / 40 CFR 110 |
| Refined products (diesel, gasoline) | Reportable quantity under the TCEQ spill rule | Texas Commission on Environmental Quality (TCEQ) | 30 TAC Chapter 327 |
Step 2: Build the sampling and analysis plan
Once the site is stabilized, response turns into assessment, and the assessment is guided by a formal Sampling and Analysis Plan (SAP). The SAP delineates the spill area, identifies potential receptors such as water wells or surface water, and establishes a systematic sampling grid. A key part of it is collecting background samples from unaffected areas to set a baseline, which prevents the costly mistake of remediating to a standard cleaner than the surrounding environment. The SAP is the document that shows regulators the work was methodical and planned rather than improvised.
Step 3: Collect the field samples with a defensible chain of custody
Field technicians execute the SAP with precision. Samples are collected from the grid points at specified depths (for example 0 to 6 inches and 1 to 2 feet) to characterize the vertical extent of contamination, then containerized, labeled, and preserved according to EPA methods. A strict chain-of-custody record is maintained from collection to laboratory delivery. Without that record, even accurate lab data can be challenged, so the documentation carries as much weight as the analysis.
Step 4: Laboratory analysis and the closure benchmark
Laboratory analysis produces the quantitative data that answers the regulator's question. For most crude, condensate, and produced-water spills in Texas, the primary question is the concentration of Total Petroleum Hydrocarbons (TPH). The RRC's cleanup standard under Statewide Rule 91 is soil below 1.0 percent TPH, or 10,000 mg/kg, and final closure generally requires at least one laboratory TPH analysis confirming the soil is below that level. For more complex spills or sites near sensitive receptors, analysis may extend to specific constituents such as benzene and other BTEX compounds or polycyclic aromatic hydrocarbons (PAHs), screened against the EPA's Regional Screening Levels.
| Parameter | Threshold | Governing body / guidance | Primary application |
|---|---|---|---|
| Total Petroleum Hydrocarbons (TPH) | Below 10,000 mg/kg (1.0%) | RRC (Statewide Rule 91) | Closure standard for most oil and produced-water spills on land |
| Chlorides (from produced water) | Site-specific, typically a few hundred to ~1,000 mg/kg above background | RRC / site-specific closure plan | Produced-water remediation and revegetation success |
| Benzene and other BTEX (soil) | Current EPA Regional Screening Level (residential or commercial) | EPA RSL | Risk screening for light-end hydrocarbons |
| Benzo(a)pyrene and other PAHs (soil) | Current EPA Regional Screening Level (residential or commercial) | EPA RSL | Risk screening for heavy-end crude components |
EPA Regional Screening Levels are updated periodically, so screen against the current EPA RSL table rather than a fixed figure; the residential or commercial value applies depending on land use.
Step 5: Remediate and verify
The lab results drive the remediation strategy. Every area exceeding the 1 percent TPH standard, or another applicable threshold, must be addressed. Common options are:
- Excavation and removal: physically remove contaminated soil and haul it to a licensed disposal facility.
- In-situ treatment: treat the soil in place through bioremediation (enhancing microbial breakdown) or chemical oxidation.
- Isolation: contain the soil with a physical barrier or cap to break exposure pathways, typically only with RRC approval.
After remediation, a final round of verification sampling in the treated or excavated areas has to demonstrate that the remaining soil meets the standard. That final data set goes to the RRC with a closure report, which formally ends regulatory oversight of the incident.
How Tektite helps
The failure mode in a spill response is rarely the cleanup itself; it is an undocumented process that cannot prove the site is closed, which leaves the incident, and its cost, open indefinitely. Tektite provides environmental compliance and spill-response support for Texas operators, running the sampling and analysis plan, maintaining a defensible chain of custody, and driving the site to a documented closure against the RRC's standards. If you have an open release or want a defensible closure protocol in place before one happens, a focused review is the place to start.
Related reading
Frequently Asked Questions
What is the TPH standard for closing a spill site in Texas?
For most crude oil, condensate, and produced-water spills on land, the RRC's cleanup standard under Statewide Rule 91 is soil below 1.0 percent total petroleum hydrocarbons (TPH), which is 10,000 mg/kg. Final closure generally requires at least one laboratory TPH analysis confirming the impacted soil is below that level.
What is a chain of custody, and why does it matter for spill samples?
A chain of custody is the documented record of who handled each sample, when, and how, from the moment of collection through delivery to the laboratory. Without a defensible chain of custody, even perfectly accurate lab data can be challenged and treated as indefensible in a regulatory context, so it is as important as the analysis itself.
How do you know how much soil to remediate after a spill?
You delineate the contamination with a sampling grid defined in a Sampling and Analysis Plan, including background samples from unaffected areas to set a baseline. Areas that exceed the 1 percent TPH standard, or another applicable threshold, are remediated, and confirmation sampling afterward has to demonstrate the remaining soil meets the standard before the site can be closed.
Do produced-water spills use the same closure standard as oil?
Not entirely. Oil and condensate closure centers on the 1 percent TPH standard, while produced-water (saltwater) remediation focuses on chlorides and the return of vegetation, evaluated on a site-specific basis rather than against a single fixed TPH number. A produced-water spill can leave little hydrocarbon but a salt-affected soil that still needs remediation.
