DR9604-SY 981020DENTON CREEK WATERSHED
TEXAS
FEASIBILITY STUDY PROPOSAL
Executive Summary
Page 1
Corp~
Fort Worth District
WHAT CAN THE FORT WORTH DISTRICT DO FOR YOUR AREA?
FEMA MODELING AND MAPPING -
You will receive a state of the art Hydrology
& Hydraulics model for the Denton Creek
Watershed, which is compatible with the new
Trinity River Model. Updated FEMA maps
will be prepared, coordinated, and submitted
for the Denton Creek Watershed.
ENVIRONMENTAL RESTORATION -
If an environmental restoration project is
determined feasible, an implementable plan to
restore riparian forest vegetation along the
old and new creek channels would be
developed. Additional benefits would include
water quality improvements (lower water
temperature) and erosion control along the
creek.
RECREATIONAL FACILITIES -
Recreational facilities can be added to a
feasible environmental restoration or flood
damage reduction project. Recreational
facilities can include hike and bike trails,
footbridges, picnic facilities, and parking
areas. Denton Creek trails could tie into the
Trinity Trails Corridor, providing a
recreational and transportation link to the
developing regional system.
FLOOD DAMAGE REDUCTION -
Ifa flood damage reduction project is
constructed, you will receive a reduced flood
damage threat to floodplain residents,
re~luced streambank erosion, and can qualify
for reduced flood insurance premiums for
portions of the ~reek.
You will receive Federal matching funds for
the study and, if a project is implemented, the
Federal government will cost share in the
design and construction of the project.
Executive Summary
Page 3
U.S. Army Corps of Engineers
Fort Worth District
FEMA MODELING AND MAPPING
Fort Worth District extensive expertise in the preparation of hydrology and hydraulic models and
mapping for Federal Emergency Management Agency (FEMA) projects ensures a quality and cost
effective product. The District's recent efforts directed toward the preparation of the Corridor
Development Certificate (CDC) and FEMA modeling and mapping for the Upper Trinity River
Feasibility Study are two examples of our capabilities.
H&H Modeling
The new Denton Creek Watershed H&H models will be based in the new HEC-RAS system. This'
model will be compatible with the new H&H model for the Trinity River, which was developed for
the Upper Trinity River Feasibility Study. These models will also be applicable for use in the
Corridor Development Certificate (CDC) program.
FEMA Mapping
The revised floodplain maps will be coordinated with FEMA to gain their approval and
certification. The new maps will incorporate the same base mapping as the CDC process and,
therefore, will be compatible or seamless when meshed together.
Executive Sunumay
Pagc5
U.S. Army Cot~ of Engineers
Fort Worth District
ENVIRONMENTAL RESTORATION
The Fort Worth District interdisciplinary team possesses the broad expertise in environmental
restoration which can be utiCLzed in the progect design to provide su~ revegetation and other
land management ~q, ivities resulting in a diversified and productive wildlife habitat in a timely and
cost effective manner.
Restoration of Vegetation
Possible restoration activities along Denton Creek could include: riparian forest stand development
and improvement using native trees, shrubs and vines; and development of wetland/shallow
water/moist soil areas. Variou~ riparian restoration opportunities exist along Denton Creek
downstream to its confluence with the Elm Fork of the Trinity River.
Water Quality
Vegetative growth is preferred over concrete or other impervious cover for a number of reasons.
First, it serves to remove pollutants from stormwater. Grasses, wetland plants and other
groundcovers act as a filter for urban and agricultural pollutants washed from surfaces by rain.
Pollutants are physically, removed by vegetation as well as broken down by microorganisms in the
soil. Thus, vegetative buffer strips could be developed between urban lands and Denton Creek in
order to protect the watershed from pollutants such as oil, grease, fertilizers, pesticides and other
compounds which enter the stream directly with stormwater. In addition to the ability to remove
pollutants from .stormwater, vegetation provides shading to protect streams from large temperature
increases in the summer and provides habitat for local wildlife.
Erosion Control
Slopes can be stabilized with a combination of hard materials, including rocks and logs, along with
living plants such as willow, the roots of which hold soil together, while its branches trap sediment
and slow stream velocities.
Ex~utive SummaO
Pag¢6
U.S. Army Corps of Engineers
Fort Worth District
FLOOD DAMAGE REDUCTION
The Fort Worth District's technical expertise in the planning, design, and construction of flood
damage reduction projects includes work on numerous major flood control projects, such as the
Dallas Floodway and on 26 multipurpose lakes located throughout the state. This experience can
be applied to develop effective solutions to the watershed's flooding problems.
Flood Damage Threat
The flood threat along the Denton Creek Watershed could be reduced by structural measures, non-
structural measures and/or combinations of these two features. Such improvements would qualify
the affected area for a reduction or elimination of National Flood Insurance Program (NFIP)
premiums and the potential for increased property values and development.
Stream Bank Erosion
Section 14 of the 1946 Flood Control Act allows the Corps of Engineers to address small flood or
erosion threats to public works and public facilities by construction or r,~ir of emergency stream
bank and shoreline protection. The implementation ora streambank erosion project would have
the benefit of preventing further stream bank erosion along the creek.
Executive Summazy
Pa~c$
U.S. Army Corps of Engineers
Fort Worth District
FUNDING
The Corps of Eh 'gmeers has a variety of programs, derived from various Congressional authorities,
to undertake the study, design, and construction of projects in the interest of developing and
managing the Nation's water resources. The project purposes can include: navigation, flood
damage reduction, environmental restoration, stream bank erosion protection, and recreation.
FEASIBIlATY STUDY COST SHARING
The local sponsor must provide 50 percent of the total Feasl"oility Study costs; up to one-halt'of
these local sponsor costs can be work in-kind. The Feasibility Cost-Sharing Agreement establishes
the conditions of the "contract" between the Federal government and the local sponsor. It also
defines a specific scope of work to be performed in the Feasibility Study.
PROJECT COST SHARING
Environmental Restoration: The current Federal policy on
cost-sharing for ecosystem restoration features is 65 percent
(Federal) and 35 percent (non-Federal) for implementation
(pre, construction engineering and design, construction), and 100
percent non-Federal for operation, maintenance, repair,
rehabilitation, and replacement.
Flood Damage Reduction
Structural Pro_iects: For structural flood control related features,
the non-Federal sponsor(s) must provide all lands, easements,
fights-of-way, relocations, and disposal areas (LERRScD) for the
project. The Sponsors total cost will vary between 35 and a
maximum of 50 percent of the total project cost including the
five percent cash contribution, ffthe total percentage is higher
or lower than these percentages, the difference in cash is to be
contributed or credited.
Nonstmct~r~ Proiects: The non-Federal cost on nonstructural projects is 35 percent of the total
project cost. The Sponsor is responsible for the LERR,gcD portion of the project requirements but
is not required to contribute any amount of cash during construction of the Project, if the
LERRScD is at least 35 percent of the total project cost.
Recreational Facilities Recreational development, including lands required for public access,
health, and safety, are cost-shared on an equal (50~50 percent) basis between Federal and
non-Federal public interests. The Federal share is capped at a maximum of 10 percent of the
Federal flood control and environmental restoration feature costs
Executive Summary
Page 9
U.S. Army Corps of Engineers
Fort Worth DisUict