Private Stormwater Management Facilities

Background


The requirement to detain stormwater runoff on-site has arisen from the increase of impervious coverage throughout the Village. This increase of impervious coverage through larger single family residences, swimming pools, tennis courts, patios, and more has reduced areas where stormwater drainage can absorbed naturally into the ground prior to entering into the Village's storm sewer infrastructure.

On-site stormwater detention ensures that new developments do not cause increased downstream flooding in either local drainage systems immediately or impact downstream rivers. With on-site stormwater detention, potential flooding problems are controlled at their source.

As subdivisions are developed, there is often a requirement to provide on-site stormwater detention for the entire subdivision. Generally, this is done through the construction of dry bottom detention basins or retention ponds and the maintenance often falls on the homeowners association. The Village has developed a map of the detention basins and retention ponds that depicts who is responsible for the maintenance of the facility.

Facility Maintenance


Regular maintenance of stormwater management facilities helps ensure proper functioning, longevity, and public safety. Properly functioning private stormwater management facilities are a crucial component in mitigating flooding risks. In addition, routine maintenance is often required as a condition of developing a subdivision or a building permit.

General Surface Grading


Land grading is the reshaping of the ground in an effort to direct stormwater in a specific direction, typically toward storm sewer inlets or overland flow routes and away from structures. For drainage swales to function properly, it is required that they be a minimum width of 18 inches and a maximum depth of 12 inches. Maintenance is required when:
  • Surface grading has changed in a way that redirects stormwater.
  • Obstructions prevent the natural flow of water.

Wet Ponds


Much like a lake, wet ponds are designed to hold water permanently. When the amount of water entering the pond exceeds capacity, water is released into the nearest creek at a controlled rate. Maintenance is required when:
  • Too much sediment accumulates and interferes with volume capacity.
  • Trees or other shrub vegetation grows on the embankment.
  • The embankment becomes denuded or otherwise presents a sediment erosion problem.
  • Visible damage to any of the mechanical equipment is present (if applicable).

Dry Ponds


Unlike a wet pond, dry ponds are designed to retain stormwater runoff generally between 48 and 72 hours after a rain event. Water that drains too quickly from a dry pond does not have adequate time to filter and can damage the banks of downstream creeks and rivers. Water retained on site too long can affect the walls of the basin or lead to algal problems. Maintenance is required when:
  • Too much sediment accumulates and interferes with volume capacity.
  • Trees or other shrub vegetation grown on the embankment.
  • The embankment becomes denuded or otherwise presents an erosion problem.
  • The low flow orifice, fore bay, or concrete trickle ditch is blocked by trash, debris, or sediment.
  • Animal burrows are present on the embankment.
  • Standing water remains longer than 72 hours after a rain event.

Example of a Dry Pond

Image of Dry Pond Grassy Area

Underground Detention


Consisting of a series of large underground pipes or chambers, underground detention facilities detain stormwater runoff and slowly release it into the storm drain system. Underground detention facilities may be coupled with other treatment facilities to remove pollutants while the runoff is detained. Maintenance is required when:
  • There is visible damage present to any of the inlets, pipes, or outlets.
  • If excessive sediment and/or debris has accumulated in the inlets, pipes, or outlets.

Rain Gardens


Mimicking natural vegetative cover, rain gardens absorb and treat runoff from pavement or yard areas through mulch, layers of soil and certain microbes. Rain gardens are maintenance intensive and require regular mulch replacement. Maintenance is required when:
  • Vegetation becomes discolored, wilted, or dies.
  • Erosion is present on the slopes.
  • The overflow riser or grate is blocked with debris.
  • Standing water is present in the basin 72 hours after a rain event.

Example of a Rain Garden

Rain Garden by Brick Building

Permeable Pavement


Made of previous materials like bricks and/or gavel, permeable pavement is typically used in parking lots or driveways to provide stormwater runoff a chance to percolate into the underlying soil, while still maintaining the structural integrity of pavement. Maintenance is required when:
  • Standing water is present 48 hours after a rain event.
  • If too much sediment has accumulated inside the pavers so that stormwater runoff absorption rate is affected.