Eagle Point-CS 920915NDM
NATHAN D. MAIER
CONSULTING ENGINEERS, INC.
September 15, 1992
Mr. Ken Griffin, P.E.
City of Coppell
255 Parkway Boulevard
Coppell, Texas 75019
Dear Mr. Griffin:
This letter is provided in regards to the Eagle Point Village project, which is located in the City of Coppell and
adjacent to the floodplain of the Elm Fork Trinity River. From prior conversations with you, we understand
that the City of Coppell is requesting that a Floodplain Fill Permit be prepared for filling approximately 20
feet within the Elm Fork floodplain to allow for the construction of a proposed alley. This fill area will be
located along the back (east side) of the alley behind lots 12 to 17 of Block E.
We have reviewed the hydraulic impacts of this 20 feet of fill on the 100 year existing floodplain which has a
width of approximately 6,200 to 7,0(X) feet at the proposed fill location. The analysis performed was based on
the U.S. Army Corps of Engineers (COE) model which was recently developed by the COE for the
Reconnaissance Study in the Trinity Rivers. The analyses was based on the existing 100 year discharge at this
location of 48,600 cfs. Cross-section #93620 and #93670 were encroached in the model to reflect the
proposed fill. There were no changes in the computed water surface elevations for this condition. In addition
to this analysis, we also reviewed the effective flow area of the Elm Fork in this area and have found that the
proposed fill is located outside of any natural area for effective flow due to the downstream reclamation at
cross-section #92300. The area is also well outside of the defined regulatory floodway.
Based on these data, we are confident that the proposed fill will have no impact on the Elm Fork floodplain.
Due to the insignificant nature of this fill, we do not believe it is necessary to submit this data tO the Federal
Emergency Management Agency. The proposed fill for the alley will not require a map revision and will not
affect either the Base Flood Elevation or the FEIMA Floodway.
If you have any further question on this matter, please feel free to call me.
William L. Wallace, P.E.
Vice-President
WLW/cmh
Three NorthPark/8800 N. Central Expwy./Sutte 300/Dallas, Texas 75231/(214) 739-4741