Oklahoma
Phase I Environmental Site Assessment
ASTM E1527-21 Phase I ESA to identify contamination risk before buying or financing commercial property.
What the work involves
A Phase I ESA reviews historical records, regulatory databases, site reconnaissance and interviews to identify recognized environmental conditions. Performed to ASTM E1527-21 and EPA's All Appropriate Inquiries rule, it helps buyers qualify for CERCLA liability protections and is commonly required by commercial lenders. It is performed by an environmental professional, who may or may not be a civil engineer.
Local conditions we plan for
- Expansive clay soils
- Tornadoes and severe storms
- Induced seismicity linked to wastewater injection
- Flash flooding
Building code: 2018 IBC/IRC adopted at the state level (ICC adoption chart, April 2026). Rules adopting newer editions were pending with a September 14, 2026 effective date.
When you need it
- Buying commercial or industrial property
- Lender requires a Phase I
- Former gas station, dry cleaner or industrial use
- Redevelopment of a brownfield
Frequently asked questions
How much does phase I Environmental Site Assessment cost?
Across the US, phase I Environmental Site Assessment usually costs $1,500 to $5,000 per site. Estimate from consultant and cost-guide sources, which commonly report about $1,500 to $5,000 for typical sites and more for large or complex ones.
How long does phase I Environmental Site Assessment take?
Plan on 2 to 4 weeks from signed proposal to stamped deliverables, longer if a site visit, soil testing or a permit review cycle is involved.
Is a permit required for phase I Environmental Site Assessment?
Often not on its own, but the findings frequently lead to work that does need a permit. We tell you which parts of the follow-up work your local building department will review, and can prepare those drawings too.
How do I verify an engineer's license in Oklahoma?
Engineers practicing in Oklahoma are licensed by the Oklahoma State Board of Licensure for Professional Engineers and Surveyors. You can confirm a license number and its status in the board's public license search before you sign a contract.
Which building code applies in Oklahoma?
2018 IBC/IRC adopted at the state level (ICC adoption chart, April 2026). Rules adopting newer editions were pending with a September 14, 2026 effective date. Cities and counties can add local amendments, which is one reason to hire an engineer who works in your area.
What site problems do engineers see most in Oklahoma?
Common issues include expansive clay soils, tornadoes and severe storms, induced seismicity linked to wastewater injection and flash flooding.