Getting a construction stormwater permit in Colorado might not be the most exciting part of your project. Understanding how it works can save you a serious headache down the road. If you will be disturbing an acre or more of soil, you may be required to have coverage under the Colorado Discharge Discharge Permit System (CDPS) COR400000 Construction Stormwater Discharge Permit. To learn more about the CDPS and other jurisdictions that require construction stormwater permits, check out our previous blog: Colorado Stormwater Agencies: State vs. Local Roles, Responsibilities, and Compliance Requirements.
Duty to Apply
Once you’ve determined that your project will need to be covered under the COR400000 permit, it’s important to understand the roles and responsibilities of a permittee. This is critical regardless of the team you have assembled to manage stormwater at your site during (and after) construction. The current permit term is effective April 1, 2024 and expires March 31, 2029. The permit is a 31-page document and will be referred to and summarized throughout this blog. If you’re interested in reading the full document, click here.
Applying for the CDPS Permit
Before you submit your permit application, you’ll need to have your Stormwater Management Plan (SWMP) either complete or certified that it will be complete before construction begins. It needs to include a site map, a description of your construction activities, the BMPs you’re using to control sediment and erosion, your spill prevention plan, and the name of your Qualified Stormwater Manager (QSM). The QSM is the person or contractor responsible for making sure everything in the plan actually gets implemented.
The permit application can then be submitted electronically through the Colorado Department of Public Health and Environment’s (CDPHE) online system. This must be done at least 10 days before construction begins. Submitting the application is not the same as being covered. You need to receive written confirmation from CDPHE before you start moving dirt. It’s important to note that both the owner and the operator have to be on the permit. This means both parties need to sign the application, and both are responsible for making sure the site stays compliant. In some cases where the owner is also managing the project, one person can sign for both.
Staying Compliant Day to Day
Once you’re permitted and construction is underway, your main job is keeping your Best Management Practices (BMPs) working and your inspections documented. While BMPs and inspections are typically contracted out to third party vendors, the responsibility will still fall on the permittee. Here’s what that looks like in practice:
BMPs need to go in before you start disturbing soil — not after the first rain event. They also need to be installed at the start of each new construction phase, not just at the beginning of the project. As site conditions change, your controls need to change with them.
Inspections are non-negotiable. At a minimum, inspections are required every 7 calendar days, or every 14 days if post-storm inspections are conducted within 24 hours of any rain or snowmelt event that causes surface erosion.
There are some situations where you can reduce your inspection frequency. Some examples would be when the site is temporarily idle, when you’re just waiting on vegetation to establish for final stabilization, or during winter at high-elevation sites where snow covers everything and there’s no melting. But these reductions come with their own documentation requirements.
Mid-Project: Modifications, Transfers, and Contact Changes
Life happens on construction projects — ownership changes, contractors swap out, contact information gets updated. The permit has a process for all of it. Skipping steps is where a lot of people get into trouble. Here are the top 3 modifications most people miss:
- Any time there’s a significant change to the scope or conditions of your project. All modifications need to go through CDPHE’s online system using their provided forms. If you’re modifying coverage and handing off a portion of the project to another permittee — like a developer selling lots to homebuilders — you need to provide CDPHE with the new permittee’s certification number.
- Transferring the permit to a new party requires written notice to CDPHE at least 10 calendar days before the transfer happens. The notice needs to include a signed agreement between the old and new permittee that spells out the exact date the responsibility, coverage, and liability switches hands. The new permittee handles submitting this agreement — but it has to be signed by the old permittee. If the incoming party isn’t planning to get their own permit coverage, the outgoing permittee needs to document their due diligence in trying to make that happen and submit that documentation to CDPHE.
- Updating contact information might seem minor, but it’s still a formal permit action that needs to go through the proper CDPHE process. Don’t just assume that changing your information in one system updates everything. Use the division-provided forms and keep a record that you did it. This will come into play down the line when you are ready to terminate your permit as all contact information will need to be accurate and relevant.
Final Stabilization and Permit Termination
The finish line for your permit closeout is final stabilization — and it has a specific definition that matters. Final stabilization is reached when all construction activities are complete, permanent stabilization methods are in place across the entire site, and all temporary control measures have been removed. For vegetative cover, this means evenly distributed perennial vegetation at a minimum of 70% of what native vegetation would provide in an undisturbed area nearby. Pavement, hardscape, xeriscape, and stabilized driving surfaces also count.
Once you’ve hit final stabilization, you need to formally terminate your permit through CDPHE. This is a step that gets overlooked more often than you’d think. And if you don’t terminate, you’re still technically covered under the permit. This means you’re still responsible for annual fees and still subject to inspections. Don’t leave it open on accident.
Where Summit Can Help
The COR400000 permit covers your project from the first day of ground disturbance to the last day of stabilization work — and every step in between. Once you understand the flow, it’s very manageable; and Summit is here to guide you through the process. Applying early, building a solid SWMP, conducting and documenting your inspections, as well as permit termination are the main areas we can provide service. Working with our clients, we stay proactive and provide a smooth permitting process – from start to finish.