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Dry Ponds Help Reduce Damage From Flooding
Many areas of the country that experience frequent heavy rains or those living in a flood plain, dry ponds are used to help control flooding through timed release of the excess water by using detention ponds. They are not designed to hold water for an extended period and typically, dry ponds should be designed to empty within 24 hours of a flooding event.
Typically, they are constructed at the lower end of an area where flooding during heavy rains has been experienced. It should be large enough to handle the amount of water expected during a heavy downpour. Dry ponds are not designed for water treatment facilities. Their job is to hold an excess amount of run off water and release it slowly into a stream that is unable to handle the sudden surge of extra water. Many large parking lots utilize dry ponds to hold water that runs off the lot to prevent flooding of properties surrounding the area.
Outlets from dry ponds should be protected from clogging and should also have above-ground access to clean out the drains if they do become clogged with debris that will often accompany heavy rains. Leaves and trash often float along with the water as it runs from lots and parking areas and can clog up the drains, preventing the pond from emptying before the next event.
Regular Maintenance Helps Prevent Future Problems
All dry ponds should be cleaned at least twice a year, removing any leaves and debris that builds up during heavy rain. Especially trash and other items than can clog screens covering drain pipes. The grass should also be kept trimmed from the bottom to the top. Some detention pond maintenance may be under the jurisdiction of the state or federal Environmental Protection Agency. Check with local ordinances to verify whether a licensed professional is required to perform lawn care in this area.
Over the course of several flooding event, sediment will build up in the bottom of dry ponds and should be cleaned every five to 20 years, depending on the frequency of the flooding events. Simply viewing the pond bottom between events will reveal the need for cleaning. When cleaning the sediment from dry ponds, it should be checked for any infiltration of chemicals before it is disposed. If none are present it can possibly make good fertilizer for on-site disposal. If chemicals are detected, proper disposal methods will have to be followed to prevent chemical pollution. |