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Stormwater Facilities

The function and appearance of stormwater facilities may differ, but their overall purposes are similar: to capture, clean, enhance infiltration into the ground, and/or release stormwater at an approved rate to control downstream flooding. Collectively, there are more than 400 stormwater facilities in Wentzville that help manage over 13 billion gallons of rainfall received, providing flood protection and improving water quality in accordance with state and federal laws.

Ownership & Maintenance

Annual maintenance and inspections are important to ensure the stormwater facilities are performing these tasks as designed. Generally, the City owns and maintains public infrastructure (i.e. residential piped infrastructure repair or blockage removal) and the property owner is responsible for private infrastructure and grounds maintenance (i.e. mowing, removing sediment/trash, or pond dredging).

What Type of Stormwater Facility Do You Have?

Traditional detention and retention basins provide flood control for our community. Newer stormwater quality facilities are also designed to treat runoff from development in accordance with the Clean Water Act. These newer facilities have a recorded Stormwater Facility Maintenance Covenant that outlines the owner’s responsibilities. In addition, an Operation and Maintenance Plan was created to guide maintenance activities specific to your site. These stormwater quality facilities require an annual inspection to be submitted to the City by the property owner, see accordions below.

Types of Stormwater Facilities

Detention Basins

Retention Basins (Ponds)

Bioretention (Rain Gardens)

Sand Filters

Dry/Wet Swales

Infiltration Systems

Hydrodynamic Separators

Pervious Pavements

If you have questions about your facility type, maintenance or inspection requirements, or if you are interested in onsite inspection training, please contact the Stormwater Division at (636) 327-5101.

Water Quality Facilities 

Over the last decade, newer facilities have been designed to improve water quality and/or help reduce erosion in streambank channels downstream. These Stormwater Post-Construction BMPs (Best Management Practices) are now a requirement of state and federal Clean Water Laws.  

For example, retention basins may also have a forebay to help settle out sediment or debris. Swales and sand filters are typically smaller and used to slow down and infiltrate runoff.  Other facilities mimic natural processes to filter pollutants from runoff. These facilities are called bioswales or biofilters. Both enhance infiltration and use vegetation, soils and natural processes to improve water quality. Other non-biological facilities include proprietary BMPs, such as hydrodynamic separators, underground detention and permeable pavement.

Click the button below to learn more about the best management practices for stormwater facilities, including pollution prevention.

Inspection Information and Resources

Stormwater Quality Facility – Required Annual Inspections

As a part of continued maintenance responsibilities, owners must perform an annual inspection that logs any maintenance or repairs performed, current owner contact information and submit the report along with a current photo to the Wentzville Stormwater Coordinator by December 31 each year to avoid compliance enforcement. Please contact the Stormwater Division at (636) 327-5101 with any questions. 

Online Inspection Portal
To determine the type of facility on your property please refer to the recorded Stormwater Facility Maintenance Covenant. The inspection checklists can be found in the buttons below. These online inspection forms will be sent to the City after submission. Please be sure to wait for the confirmation page to ensure the data was successfully submitted. 

For proprietary BMPs, refer to your specific user manual and Operations & Maintenance Plan. The inspection form found in the manual/maintenance plan can be uploaded here.

Other Detention or Retention Basin – Inspections Recommended

Detention Basins
Traditional basins temporarily detain stormwater and release it at a reduced rate for flood control. Annual inspections and maintenance are recommended to ensure they function properly.

Retention Basins
Typically, these basins permanently hold water (as an amenity), while detaining and releasing additional flows at a reduced rate (for flood control). Annual inspections and maintenance are recommended to ensure they function properly. If your pond was designed more recently, it may also be a Post-Construction Water Quality BMP.

Inspections and Maintenance Report Forms