Q:

What is stormwater

A:

Stormwater is runoff that is a direct result of precipitation. It flows in concentrated forms (pipes, gutters, channels, etc.) and diffuse forms (sheet flow) over or within all land forms. Stormwater infiltrates into the soil and becomes ground water, is used by vegetation or flows into lakes or streams as surface flow.

Q:

Why do we need to manage stormwater?

A:

Urbanization causes significant changes in stormwater runoff characteristics, including increased volume and rate of runoff entering streams and the storm sewer infrastructure and reduced amounts of water filtering into the soil.

Such changes cause increased erosion and formation of gullies in upland areas, increased in-stream scour and erosion, increased sediment deposition in lower areas, degradation of water quality, peak storm flows that are higher and faster, more frequent flooding, and negative effects on stream ecological communities.

These impacts on both man-made structures and natural systems require continuous management, maintenance, repair and replacement of the Town's stormwater management system, and careful planning to mitigate existing and future problems.

Q:

Who maintains detention (dry pond)/retention (wet pond) basins?

A:

These basins are usually located in the common ground for a subdivision therefore; maintenance becomes the homeowner’s association responsibility. Periodic maintenance beyond mowing is required such as removal of trash/debris and removal of excess sediment build up.  The City does perform periodic inspections to make sure that the basins are functioning as per the approved design plans.

Fact sheet: Detention-Retention Basin (PDF)

Q:

Who maintains the storm sewer in my yard?

A:

The city provides maintenance to all storm sewers located within City limits.  Common maintenance issues include, but are not limited to sinking around the outside which causes a sinkhole, missing lid or damaged structure. Contact the Street Division for maintenance concerns at 636-379-3808.

Q:

Why do I have a “river” through my back yard when it rains? 

A:

In most back yards, there is a drainage swale (U-shaped or depressed area) that provides a pathway for stormwater runoff to travel through to get to a Stormwater inlet.  When we have a large amount of rainfall in a short period of time, these swales can become quite full and look like a river running through you yard.  Once the rain subsides and the runoff amount decreases, your yard should return back to normal and the river should disappear. Once the "river" disappears, you may experience your yard being wet or soggy for several days after. This is how the swale is supposed to perform.  If you experience flooding of your yard beyond this section during a normal rain event, feel free to contact Stormwater Management at 636-240-2000 for further discussion of your concern with the Stormwater Management Coordinator.

Q:

Who maintains the creek in my back yard? 

A:

There are many creeks that travel throughout the City limits.  When a creek travels through private property, the owner of that property is normally responsible for maintenance in keeping it free from excess debris, trash, and addressing creek bank erosion concerns. The City performs the same duties on creeks that travel through City owned property as well. Should you have a concern relating to creek bank erosion, feel free to contact the Stormwater Management Coordinator for suggestions and possible City assistance at 636-240-2000.

Q:

What is the difference between a storm sewer line and a sanitary sewer line? 

A:

O'Fallon does not have a combined sewer system in which Stormwater runoff and sanitary sewer discharge travel in the same pipes.  Storm sewer lines carry only stormwater runoff and are independent of sanitary sewer lines.  Stormwater is not treated water; it does not travel through a pipe to a public owned treatment works facility for cleansing prior to it exiting to a local creek/stream or river. What gets picked up along the way usually ends up in our local creeks and then travels to the Mississippi River untreated. Sanitary sewer lines carry sewage from a building through a “force main” which discharges as a local public owned treatment facility. The discharge is cleansed for federal/state requirements and then discharged to the river.

Q:

What kinds of discharges are prohibited per the Stormwater Quality Management and Illicit Discharge Control ordinance?

A:

No person shall discharge or cause to be discharged into the municipal storm drain system or watercources, any materials, including but not limited to pollutants or waters containing any pollutants that cause or contribute to a violation of applicable water quality standards, other than Stormwater.  Pollutants may include, but are not limited to: paints, varnishes, solvents; oil and other automotive fluids; non-hazardous liquid and solid wastes and yard wastes; silt, garbage, litter or rubbish, pesticides, herbicides and fertilizers, sewage, and animal wastes.