Looking for a Phase I ESA in Castle Rock, CO? Describe your project once and up to three environmental consultants who work in Castle Rock and Douglas County get back to you with a quote. It's free and there is no obligation.
Castle Rock is home to about 83,213 people (2024 Census Bureau estimate), a growing community (+13.7% since 2020). With 2,395 people per sq mi, it is a suburban area. Commercial sales and loans here routinely require a Phase I, especially for former industrial, gas station and dry cleaning sites.
Castle Rock at a glance
- Population (Census Bureau estimate, 2024)
- 83,213 (+13.7% since 2020)
- Rank in Colorado
- 14th of 271 cities and towns
- Land area
- 35 sq mi
- Population density
- 2,395 people per sq mi (suburban)
- Type
- Town (Castle Rock town)
- Main county
- Douglas County
What to check before hiring in Castle Rock
- Qualifications: the report is signed by an Environmental Professional under the EPA All Appropriate Inquiries rule; some states also license environmental consultants.
- Lender requirements: check whether your lender has its own scope or reliance letter requirements.
- Timing: order early: records requests and the site visit take time.
- Price drivers: property size and history, number of buildings and turnaround.
Useful official resources
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EPA: brownfields
All Appropriate Inquiries and brownfields programs.
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ASTM International
Publisher of the E1527 standard.
Services available in Castle Rock
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Phase I Environmental Site Assessment
Records review, site visit and interviews to ASTM E1527 by an Environmental Professional, for a purchase or a loan.
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Phase II Environmental Site Assessment
Soil, groundwater or vapor sampling when a Phase I identifies a recognized environmental condition.
Frequently asked questions in Castle Rock
How much does a Phase I ESA cost in Castle Rock, CO?
It depends on the size and history of the property and the turnaround. Describe the property: consultants who serve Castle Rock send a proposal.
How long does it take?
Often two to three weeks; rush service is usually available.
What if the Phase I finds something?
A Phase II may be recommended to sample soil or groundwater and assess the extent.
Which environmental consultants will contact me?
Up to three independent environmental consultants who serve Castle Rock and the surrounding area, chosen for the service you need. Your details are shared only with your consent.
Source: U.S. Census Bureau, Population Estimates Program (Vintage 2024) and Gazetteer Files (public domain), imported on 10/31/2026. Figures describe the incorporated place or county as published; they are shown for information only.