City of Duncanville

Floodplain Administrator Responsibilities

The Floodplain Administrator is responsible for administering and implementing the provisions of the city's Flood Damage Prevention Ordinance. It is the floodplain administrator's responsibility to:

• Approve or deny land-disturbing activities in the Special Flood Hazard Area
• Assure that all other necessary permits, including federal and state permits, are approved
• Maintain records
• Make necessary interpretation of floodplain boundaries where conflict between mapped boundaries and actual field conditions exists
• Notify adjacent communities, TCEQ, and FEMA prior to any alteration of watercourse
• Obtain, review, and reasonably utilize base flood elevation data in order to administer the provisions of the Flood Damage Prevention Ordinance
• Review and approve floodplain development permit applications

City Floodplain Information Services: The City can determine the relationship of a particular property to the floodplain, including: 1) whether the property is located within the Special Flood Hazard Area; 2) Flood Insurance Rate Map (FIRM) Zone for property; 3) Base Flood Elevation for property, if available; and 4) whether the property is located within the Floodway. Contact the City Floodplain Administrator at (972) 707-3856 or the Federal Emergency Management Agency, Region VI, at (904) 898-5127 for further information.

General Floodplain Information

Overview

The City of Duncanville features several large creeks and smaller tributaries, or streams, which are susceptible to annual flooding events that pose threats to life and safety and cause significant property damage. Large creeks include Ten Mile Creek, Horne Branch, and Mauk Branch. There are also several small tributaries that drain into these creeks. Duncanville has approximately 480 acres of floodplain.

Recent Flooding Events

While some sort of seasonal flood-related damage occurs nearly every year, the flooding event of August 2022 represents the most recent significant flooding. The City also experienced significant rainfall events in May 2015, July 2004, August 2001, twice in the early 1990s, and twice in the mid-1980s.

Causes of Flooding in Duncanville

Flooding occurs when climate (or weather patterns), geology, and hydrology combine to create conditions where river and stream waters flow outside of their usual course and spill out beyond their banks. In Duncanville, the combination of these factors, augmented by ongoing development, create occasional seasonal flooding conditions.

Although flooding may occur at any time, the flooding events in Duncanville have most commonly occurred between the months of April and October. Larger floods result from heavy rains that continue over the course of several days.

Flood Insurance

The City of Duncanville participates in the National Flood Insurance Program (NFIP) that makes available federally backed flood insurance to insure against flood loss. To participate in the NFIP, the City must adopt and enforce floodplain management ordinances that meet or exceed minimum requirements set by the Federal Emergency Management Agency (FEMA). These requirements are intended to prevent loss of life and property and reduce taxpayer costs for disaster relief as well as minimize economic and social hardships that result from flooding.

Most people who live in NFIP participating communities, including business owners, renters, and condominium unit owners, are eligible to purchase flood insurance. A residential building can be insured up to $250,000 and its contents up to $100,000. Renters can cover belongings up to $100,000, and non-residential property owners can insure their buildings up to $500,000 and contents up to $500,000.

FEMA encourages flood insurance policy holders whose homes are damaged extensively by flood to ask their claims adjuster or agent about Increased Cost of Compliance (ICC). ICC provides up to $30,000 to help cover the cost of mitigation measures that will reduce flood risk. ICC coverage is a part of most standard flood insurance policies available under NFIP.

Residents who live in high-risk areas, referred to as Special Flood Hazard Areas (SFHA), are required to purchase flood insurance if they have a mortgage from a federally regulated lender. They also must carry the insurance for the life of the mortgage. Residents with a mortgage on a building outside high-risk areas can also purchase flood insurance and may be eligible for Preferred Risk Policies.

In general, a policy does not take effect until 30 days after the purchase of flood insurance. However, if a policy is purchased in connection with a mortgage or at a set time period following the revision or update of a Flood Insurance Rate Map (FIRM), the waiting period does not apply. For information regarding flood insurance and how to purchase it, contact your local insurance agent.

Floodplain Understanding and Regulation

Maintaining the flow capacity in streams requires cooperation and assistance to prevent flooding and bank erosion. Following are some suggestions and information for understanding the ways that floodplains function and how the City regulates the floodplain in order to protect property and lives, while affording residents the ability to obtain floodplain insurance.

Do not dump or throw anything into ditches or streams: A blocked channel cannot convey water, and when it rains, the excess water must go somewhere. Trash and vegetation dumped into a stream degrades water quality of both the stream itself and its receiving waters, and every piece of trash contributes to flooding. The City has adopted and enforces storm water regulations that prohibit the dumping of material into any natural or manmade component of the drainage system. Additionally, the City as a whole has adopted and enforces storm water regulations that prohibit the illegal dumping of material, including material dumped into ditches, streams or other drainageways. Please report any observations of the dumping of debris or other objects into streams, drainageways, or rivers to the Neighborhood Services Department at (972) 780-5040.

Remove debris, trash, loose branches and vegetation: Keep banks clear of brush and debris to help maintain an unobstructed flow of water in stream channels. Do not, however, remove vegetation that is actively growing on a stream bank. Streamside vegetation is tightly regulated by local, state and federal regulations. Before undertaking any removal of streamside vegetation, contact the Neighborhood Services Department at (972) 780-5040. Please report any observations of the clearing of vegetation or trees on stream banks to the Neighborhood Services Department at (972) 780-5040.

Obtain a floodplain development permit and/or building permit, if required: To minimize damage to structures during flood events, the City requires all new construction within the Special Flood Hazard Area (SFHA) elevated so that the lowest floor of living space, as well as all mechanical and services, is at least 2 feet above the elevation of the 100-year flood. These standards apply to new structures and to substantial improvements of existing structures. The City defines a substantial improvement as any reconstruction, rehabilitation, or addition to an existing structure, the cost of which exceeds 50 percent of the structure's appraised or market value. Additionally, most other types of development within the floodplain also require a floodplain development permit, such as grading, cut and fill, installation of riprap and other bank stabilization techniques. City staff is available to undertake site visits, if requested, to review flood, drainage, and sewer issues. Contact the City Floodplain Administrator at (972) 707-3856 for further information and prior to undertaking any activity within the floodplain.

Recognize the natural and beneficial functions of floodplains to help reduce flooding: Floodplains are a natural component of Duncanville's environment. Understanding and protecting the natural functions of floodplains helps reduce flood damage and protect resources. When flooding spreads out across the floodplain, its energy is dissipated, which results in lower flood flows downstream, reduced erosion of the stream bank and channel, deposition of sediments higher in the watershed and improved groundwater recharge. Floodplains are a scenic and valued wildlife habitat. Poorly planned development in floodplains can lead to stream bank erosion, loss of valuable property, increased risk of flooding to downstream properties and degradation of water quality.

Reduce risk of damage to homes: Methods for reducing the risk of flooding may be available to property owners whose homes have experienced damage from flooding in the past, or may experience damage in the future. For further information, contact the City Public Works Department at (972) 780-5015. City Public Works officials are available for site-specific visits to answer any questions you might have concerning your property.

Flood Safety Tips

The City opens the Emergency Operations Center (EOC) in advance of severe weather events. In case of an emergency, you may call 911 for assistance.

The following is a list of important considerations that should be followed during times of flooding:

• Prepare an evacuation plan before the floodwaters hit: Develop an evacuation plan among all members of a household that includes a meeting place outside of the house, as well as an escape route out of the floodplain and away from floodwaters.
• Do not walk through flowing water: Drowning is the number one cause of flood deaths, mostly during flash floods. Currents can be deceptive; six inches of moving water can knock you off your feet. If you walk in standing water, use a pole or stick to ensure that the ground is still there.
• Turn Around Don't Drown: More people drown in their cars than anywhere else. Do not drive around road barriers; the road or bridge may be washed out.
• Stay away from power lines and electrical wires: The number two flood-associated death after drowning is electrocution. Electrical current can travel through water. Report downed power lines to TXU Electric Delivery Company 1-888-313-6862.
• Shut off gas and electricity and move valuable contents upstairs: Be prepared in advance with a detailed checklist because warning of an impending flood may provide little time for preparation prior to evacuation.
  
• Look out for animals, especially snakes: Small animals that have been flooded out of their homes may seek shelter in yours. Use a pole or stick to poke and turn things over and scare away small animals.
• Look before you step: After a flood, the ground and floors are covered with debris including broken bottles and nails. Floors and stairs that have been covered with mud can be very slippery.
• Be alert for gas leaks: Use a flashlight to inspect for damage. Do not smoke or use candles, lanterns or open flames unless you know that the gas has been turned off and the area has been ventilated.

Important Contact Information

1. City of Duncanville Floodplain Information: www.duncanville.com
2. City of Duncanville Flood Damage Prevention Ordinance: Reference Chapter 9A of Code of Ordinances
3. City of Duncanville Storm Water Ordinance: Reference Chapter 21
4. Federal Emergency Management Agency (FEMA Region VI) Phone: (940) 898-5127;

Fax: (940) 898-5195; Web: www.fema.gov/nfip/

5. City Neighborhood Services Department Phone: (972) 780-5040
6. City Public Works Department Phone: (972) 780-5015; Fax (972) 780-6426
7. City Water/Sewer/Environmental Department Phone: (972) 780-4900
8. Duncanville Library System (Houses floodplain publications and other floodplain information). Phone: (972) 780-5050
9. USGS Real-Time Water Data for Texas: waterdata.usgs.gov/tx/nwis/rt

Benchmarks (GPS Control Network)

Monuments have been set throughout the City at designated key areas. All fieldwork and post processing was performed by The Wallace Group.

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