Stormwater Quality
What is stormwater?
Stormwater is precipitation, such as rainwater or melted snow, that falls to the ground and either soaks into the ground or runs off streets, houses, etc., and flows into our local ponds, lakes, streams, and rivers—such as the Poudre River.
What is the problem with stormwater?
In Greeley, rain and other stormwater flows through a special system of pipes and ponds—separate from drinking and wastewater—and eventually drains into a stream, lake, or river. It does all that without ever going through an artificial treatment system—such as a wastewater treatment plant.
That means everything from spilled coffee, to leaked motor oil, everything that falls on or is deposited on roadways, lawns, and parking lots all mixes together and can cause stormwater pollution in our streams, lakes, and rivers.
Stormwater Ponds
What is an extended detention basin (EDB)/stormwater pond?
An extended detention basin (EDB), also called a stormwater pond, holds stormwater for an extended period. That allows pollutants to settle out and get naturally removed from the water before it goes into our streams, lakes, and rivers.
A typical EDB includes one or more inlets, which allow stormwater to flow into the pond, a channel that conveys the stormwater from the inlets to the outlet, and an outlet structure.
The EDB on your property may provide other benefits including recreation and open space opportunities in addition to reducing peak runoff rates and improving water quality.
Stormwater Pond Ownership
Who owns and operates this EDB?
You do. As the owner property, the manager of a commercial site, or as a member of a Homeowner Association (HOA) with an EDB, you have the responsibility to operate and maintain it.
There must be a designated party responsible for proper operation of the EDB. In some instances, that may be a shared responsibility. In the majority of cases, the property owner or the HOA is responsible for the correct operation and proper maintenance of the EDB.
The City of Greeley has the authority to inspect and review maintenance activities of the EDB. Those inspections occur every two years, to ensure the viability of your EDB. City of Greeley officials can impose fees to the owner of an out-of-compliance EDB.
Owners need to assure the EDB’s continued proper function to ensure control and proper treatment of stormwater. As the owner of the EDB, it is important for you to take the time to walk around your facility and become familiar with all of its features and components.
The information below provides the information and the resources you need to operate a fully functional EDB on your property.
Stormwater Pond Maintenance
Why does your EDB need to be regularly maintained?
Improperly maintained EDBs can increase the stormwater pollutants in our rivers, increase flooding risk, and increase the amount of erosion that could occur. Improperly maintained EDBs can also lead to legal liabilities.
Over time, EDBs accumulate dirt, trash, sediment, vegetation debris, etc. which reduces storage capacity and functionality. Yearly maintenance ensures that accumulation does not compromise your EDB’s functionality.
City of Greeley officials can impose fees on the owner of an out-of-compliance EDB.
Why do some EDB’s fail and what does that mean for water quality?
Poor maintenance causes the majority of EDB failures. When an EDB fails it means it’s not properly detaining stormwater and allowing pollutants to settle out. Poor maintenance can also create unpleasant odors, nuisance insects, algae blooms, and a generally unsightly and unkempt area. Poorly maintained EDBs can also contribute to surface water pollution that kills aquatic life and vegetation.
EDBs may fail due to:
- Poor vegetation maintenance such as mowing and weed control
- Clogged inlets caused by trash, debris, and sediment accumulation
- Exposed soil or eroding side slopes in and around the EDB
- Inadequate access for routine maintenance activities
Knowing and understanding why an EDB was built at your property or in your subdivision community and the importance of all components working together should reduce the chance of EDB failure.
What should you be doing to maintain your EDB, prevent it from failing, and protect stormwater?
To ensure a functional EDB it must receive routine inspection and maintenance. If maintenance is not done, not done frequently enough, or done improperly it may not function properly.
Routine maintenance, including mowing and debris removal, needs to take place on a regular basis.
Non-routine maintenance, including slope stabilization and sediment removal, needs to take place on an annual, as-needed basis. Every EDB is different in the size, type, shape, and characteristics of the tributary area that contributes runoff to the EDB, as well as the location of the EDB.
- An EDB serving a large commercial district will likely require more maintenance than a smaller one serving a neighborhood. A pond in a prominent location in a development may require more frequent collection of trash.
- Maintenance considerations for a wet pond need to focus on floating litter, scum and algal blooms, shoreline erosion, possible unpleasant odors and mosquitoes, and more difficult sediment removal.
- Maintenance considerations for a dry pond will concentrate more on mowing to control the vegetation and frequent removal of the trash and debris that may clog the outlet or trash rack.
- All EDB maintenance should include:
- Removing trash and vegetation debris from inlets, trickle channels, and outlet structures
- Preventing EDB and pipe system clogging by removing obstructions
- Cleaning and removing sediment from inlets, trickle channels, and outlet structures
Routine inspection and maintenance can help prevent the need for costly repairs down the road and helps improve water quality in the meantime while keeping the EDB in compliance.
How can you cover costs of maintaining your EDB?
The property owner or the HOA should consider establishing an Operations & Maintenance (O&M) fund and assess annual fees for maintenance of the EDB. Sometimes fees are established by the developer prior to turning the responsibility of the EDB over to the owner. After several years of operation with these set fees, it may be necessary to re-evaluate maintenance costs for the actual operation of the pond after the development is established.
Annual Stormwater Pond Inspections
What are the minimum components of a routine EDB inspection?
The minimum checklist components of a routine (annual, or as needed after a storm event) EDB inspection are as follows: (A good time to fill out the checklist is every time routine maintenance is done; while mowing, someone can check the other features, too.)
- Any obstructions of the inlet(s) or outlet of EDB?
- Has trash accumulated in the pond or on the trash rack/well screen?
- Any erosion or instability of the side slopes?
- Any sedimentation in the basin?
- Are there any upstream or downstream conditions that could affect pond operation?
- Is trickle channel conveyance in good working order with no sediment, vegetative growth, or trash accumulation?
- Is outlet channel conveyance in good working order with no sediment, vegetative growth, or trash accumulation?
An example of an EDB Inspection Form can be downloaded here.