Big Storms / Big Problems
Over the past year, the northeastern United States has experienced several record setting rain events that have caused flooding and damage to many residential neighborhoods. Although these events are rare and unpredictable, proper maintenance and proactive planning can help improve your community’s ability to control future flooding conditions.
Many residential communities are responsible for maintaining one or more on-site storm water basins. These basins are key components to how storm water is controlled within a community and should be cared for accordingly. In some communities, these basins are buffered from view or may be shared among multiple developments. Having a specific understanding of the locations and the condition of each basin servicing your location is very important.
Over the years, the techniques used to design and construct storm water management systems have not changed too much. The principle behind designing a basic detention basin is to estimate the amount of rain that will fall during a certain event and then distribute that over the areas (roads, buildings and open space) of the development. The volume of water that is generated from these storms is calculated and then a detention basin is sized to accommodate that volume of runoff. The detention basin is designed to empty over a period of time so that downstream areas are not surcharged with the runoff all at once.
Although this concept has been in place for many years, it was not always implemented on projects constructed many years ago. In some cases, older communities may have little to no storm water management facilities. In addition, older communities may have been designed using less conservative assumptions about the likelihood of very intense rain events. In other words, older communities may be more susceptible to flooding if their storm water management systems have not been upgraded or improved over the years. These systems should be evaluated for possible improvements.
Maintenance of these systems includes simple tasks such as mowing and leaf collection but also requires more technical inspection of the overall system. For example, the outlet structure, inlet pipes, inflow structures and outlets should be inspected at least once a year to be sure they are clear of debris and structurally stable. Heavy rain events can cause erosion and damage to structural elements of the basin that should be checked.
In some cases, communities are required by their declaration to have a detailed maintenance plan for their storm water management facilities. These requirements are sometimes put into place during the original permitting and approval of the development or may be required by local ordinances. These obligations can be enforced by the local municipality or other state and federal agencies. All communities and other developments should be aware of what their obligations are for maintenance of their storm water facilities.
Failures of retaining walls, many times are related to lack or deficient drainage behind the wall. The water accumulates and creates great pressure on the wall. Aging walls can be more susceptible to this type of failure. These defects can weaken a wall after each large rain event until eventually a failure can occur. Periodic inspection of walls should be made, especially large walls or walls that support buildings or roads/ parking areas.
Flooding or Storm Erosion
Heavy rains can cause flooding or erosion that can undermine roadways, building or deck footings especially where ground cover is not established. Inspections of properties after major storms should be made to observe any of these potential issues.
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This article was reprinted with the kind permission of CAI Diamond Partner, The Falcon Group. For more information or to contact The Falcon Group, please click here or send them an e-mail by clicking here.