General Drainage Policies Outlined by Tennessee’s Department of Transportation

General Drainage Policies Outlined by Tennessee’s Department of Transportation

Drainage is a fundamental factor to consider when it comes to good roadway design and construction. There are a number of laws, rules and practices applied to highway drainage design. If these laws are not taken into consideration, liability can fall on responsible parties. In terms of liability, the goal of roadway drainage should be to create a natural and practical drainage pattern. The courts disprove of injuries or accidents that could have been avoided with proper designing and planning of roadways and drainage.

Policy, as defined by Tennessee’s DOT, “is a definite course of action or method of action, selected to guide and determine present and future decisions.”

Design Criteria is defined as “the standards by which a policy is carried out or placed in action. Thus design criteria are needed for design; policy statements are not.”

Federal law does not handle issues related to drainage, but there are still important laws in place regarding proper drainage practices. Some of these laws include:

-You must rely on proper construction and obtain flood insurance an in areas prone to floods.

-Proper systems to control water pollution are implemented.

-The right environmental protection polices are put in place.

-Local fish and wildlife are protected to the best of your ability.

National Flood Insurance

To qualify for insurance, communities must take the right steps for adequate land use and control measures; this can impact highways.  The Flood Disaster Protection Act of 1973 states that any community in a flood prone region that fails to meet the basic standards for flood insurance will be denied Federal financial assistance in the instance of a flood. Certain land usage requirements may determine where you can develop highways, for instance floodplains and floodways are generally off limits—and for good reason.

NFIP Maps

National Flood Insurance Program maps are used to identify areas prone to flooding. Whenever available, these maps are used to determine if a location is suitable for the development of a highway or roadway. There are 3 different types of maps, including:

-Flood Hazard Boundary Map (FHBM)—This type of map is not based on detailed hydraulic studies, therefore the results are approximate.

-Flood Boundary and Floodway Map (FBFM)—This map is based on detailed hydraulic studies and provides more accurate information than FHBM.

-Flood Insurance Rate Map (FIRM)—This map is made at the same time and with the same resources as the FBFM. It includes appropriate rate zones and base flood elevations.

All communities do not have access to all 3 of these maps, so it depends what’s available in your region.

What About Wetlands?

There are plenty of wetlands in Tennessee, which are protected under many laws and regulations. The Executive Order 11990 states each Federal agency must:

-Do everything in their power to reduce loss or damages to wetlands, while preserving the natural benefits of wetlands.

-Never assist in the undertaking of new developments in wetlands unless there is no “practicable alternative and all practicable measures are taken to minimize harm…”

-Consider all factors involved to assess if it’ll negatively impact the wetland.

Types of Waters

There are different classifications of waters, and depending on the classification, different responsibilities to dispose of water exist.

Surface waters are water that comes from the sky and spreads over the ground; it must be channeled and collected into an area.

Flood waters are escaped stream waters that have overflown into connected lands. They remain flood waters until they dissipate or return to their natural body of water.

Stream waters originate as surface or ground waters that have transformed into a defined waterway or water course. A water course is defined as having a channel with bed, banks and constantly flowing water.

Ground Waters are percolating water (any water that passes beneath the earth’s surface) or underground streams. 

The presence of waterways is taken into consideration for many aspects of a construction project. A common law that impacts stream water regulations states, “Water runs and ought to run as it is by natural law accustomed to run.” 

Making Sense of Government Regulations

Constructing highways, roadways and their adequate drainage systems is far from an easy process, especially with so many rules and regulations in place. These rules are here to protect the public and Tennessee’s beautiful ecosystems. Allow us to help you make sense of it all with top-notch commercial construction you can count on.