Litigation Issues Arising from Stormwater Problems

TASA ID: 355

Changing weather patterns have led to a large number of flooding and drainage problems. For example, the high intensity rainfalls that have occurred on Long Island in the last few years have resulted in record high groundwater levels and unusually severe flash floods.

This has caused extensive water damage to residential and commercial property, as well as sewage backups into buildings, resulting in a number of legal actions by the injured parties in an attempt to recover damages that they have suffered.

 The following are the initial steps that are usually taken when investigating flooding and drainage problems:

   - The storm event is analyzed - the total rainfall and how it was distributed. Although typical precipitation data is measured over a 24-hour day, the damaging events usually occur during the more intense short-time peak flows.

   - The return interval, or frequency, of the storm is determined. This is the maximum rainfall that would reoccur in a specific number of years. For example, every two, five, or 10 years.

   - The return period that was used to design the storm sewers is obtained.

   - Preventive maintenance practices for the sewer, if any, are checked.

   - Confirmation with state and local laws is checked.

Usually, this information is readily available.  In most cases, the investigative phase of the work would be relatively short, and analysis of the data could be initiated relatively quickly.

The work to be done involves determining the cause of the incident and includes, but is not limited to, analyzing rainfall events and intensities, and evaluating flood flows, effects of rising groundwater levels, soil characteristics, topography, coastal flooding, capacities of existing drainage and sewerage facilities, and preventive maintenance practices.

As indicated above, storm water drainage systems are designed by using a rainfall intensity frequency of a magnitude that reoccurs in a specific number of years. For example, the New York State Department of Transportation designs its drainage pipes for highways by using the maximum rainfall frequency that occurs once in every 10 years. Some municipalities design their systems for drainage pipes that serve small subdivisions for a lesser maximum rainfall frequency - one that occurs every two or five years. Other factors that are considered in these analyses are the sizes of the drainage areas and the ability of the surfaces on which rain falls to absorb the water. For example, permeable lawns and natural areas allow greater infiltration of the rain into the ground, while impermeable asphalt paving and roof surfaces result in more surface runoff. 

Some projects can be multi-year projects that involve FEMA- sponsored All Hazard Mitigation and Flood Plain Mitigation studies for municipalities. These may deal with encroachment from local rivers and streams and from surface waters (i.e. Long Island Sound and/or the Atlantic Ocean). Work on these projects may involve everything from the determination of flood risk to the probable cost of repairs and restoration of structures for individual residences and municipalities. Some problems involve rising groundwater levels, which have caused damage to large septic systems and to entire communities,  resulting in the construction of replacement systems.

Whenever legal action is involved, it is important to retain environmental experts with engineering and hydrogeology skills and related experience in stormwater problems. These cases demand not only knowledge of the engineering and scientific principles of surface and groundwater, but also may require providing expert testimony and working with attorneys, government agencies, and municipalities in matters concerning infrastructure, permits, maintenance records, and other pertinent matters.

This article discusses issues of general interest and does not give any specific legal or business advice pertaining to any specific circumstances.  Before acting upon any of its information, you should obtain appropriate advice from a lawyer or other qualified professional.

This article may not be duplicated, altered, distributed, saved, incorporated into another document or website, or otherwise modified without the permission of TASA.

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