Flooding & Stormwater Management Expert Article

Litigation involving flooding and storm water management issues often seeks to determine if construction or land development activities have affected the existing flow of water in a manner that has caused property damage or personal injury.

In this article, Land Development Expert, Donald Hemphill, P.E., explores some of the factors that may be relevant to flood-related litigation.

Flooding & Storm Water Management Investigations

The water cycle can be thought of as water moving from the ground to the atmosphere and back again. The precipitation phase of the water cycle results in water landing on Earth’s surface, collecting in depressions or flowing by gravity along natural or modified travel paths.

Surface water flows are commonly categorized as sheet flow, shallow concentrated flow, or channel flow. Human made modifications to the travel path of water may have adverse or unintended consequences and outcomes.

Flooding is often associated with standing water, but water flowing on or through a property, even at shallow depths, may also be considered flooding and can result in significant damage, including:

• Structural damage to buildings
• Moisture (or lack of moisture) related damages
• Erosion of soils from the land
• Deposits of silt, sediment & other contaminants
• Washout of roads & other infrastructure
• Injuries caused by water flows or travel restrictions

Litigation may also result from the restriction of surface water flows; when changes in drainage characteristics reduce or eliminate the flow of water to ponds, wells, agriculture, or vegetation.

Factors Affecting Drainage and Flooding

Absent changes to the landscape or human interventions, water naturally runs downhill, accumulating in rivers and streams, and flowing into lakes or oceans. Along the way, water may permeate the soil or otherwise be reduced by evapotranspiration.

Large-scale land development projects and dams are clearcut examples of modifications to the natural landscape, but a broad range of constructed improvements have the potential to affect the flow of water.

• Regrading Land: influences the magnitude and direction of water flows
• Hardscaping/Paving: increases impervious cover/decreases soil permeation, and increases runoff
• Drainage Systems/Pipes: collects, transports, and discharges water
• Basins/Outlet Controls: stores and release water at a designed rate
• Levees/Berms: obstructs or channelizes the flow of surface water
• Culverts: allows water to flow through barriers of earth or other materials

Designing & Modeling Waterways

Civil engineers, including those specializing in land development, model the combined system of natural and constructed waterways and flowways to achieve specified performance characteristics during target (i.e., design storm) events.

Models and designs are typically prepared in accordance with regulations and design criteria. They are often reviewed and approved by one or more jurisdictional authorities before a permit to construct is issued.

The owner and operator of drainage and storm water management systems can be a home/property owner, a special purpose not-for-profit entity (i.e., an HOA or POA), an agency or unit of government, or other authorized public/private entity.

Did Construction Cause or Exacerbate Flooding?

A forensic analysis may be useful in determining causation; typically requiring an understanding of the timeline and what changed within applicable watershed boundaries.

Relevant documents for discovery often include:

• Photo/video evidence before, during, and after storm events
• Construction plans and drainage studies
• Topographic data and boundary surveys prepared by registered professional land surveyors
• Data and studies from FEMA, USDA, USGS, and other agencies/authorities
• Rainfall records/weather data from NOAA and the National Weather Service

Ideally, construction plans and drainage studies of the designed improvements are available and reviewed for compliance with industry standards and local, state, and federal regulations. Supplemental analysis may also be conducted using topographic and parcel data available from Geographic Information Systems.

In some cases, the improvement may not have been constructed “per the plans,” potentially resulting in unanticipated functionality. In these cases, review of As-Constructed plans and current topographic survey information may shed light on changes made during, or resulting from, construction.

Experts frequently conduct in-person site investigations to observe field conditions, collect information, and take measurements.

Flooding Incident Expert Witness Investigations

Did the neighboring property owner’s actions cause substantial harm? Were the actions improper, unreasonable, and/or foreseeable? Our experts have the necessary training, education and experience to answer these critical questions relevant to flooding, drainage, hydraulic trespass, and storm water management related disputes.

For more information, submit an inquiry or call us at 800.813.6736.

Featured Expert

Donald M. Hemphill, P.E.

Civil Engineer & Land Development Expert

Donald is a civil engineer with nearly three decades of experience in land development and infrastructure projects. He understands the development process from the beginning of concept planning and… read more.