Riverview Estates-CS 950914To:
From:
Peter G. Smith, City Attorney
Kenneth M. Griffin, P.E., Asst. City Manager/City Engineer
25 acre tract of land south of Sandy Lake Road
(Johnny Thompson tract) (Riverview Estates)
Date:
September 14, 1995
This is written as a follow-up to our telephone conversation of September 13, 1995 in which we
discussed whether or not the preliminary plat for the referenced tract of land was still valid.
Also, we discussed if Mr. Thompson had any vested rights in regards to current ordinances or
fee requirements since he had previously submitted the preliminary plat.
I am providing you copies of the preliminary plat information and the backup information from
the Planning and Zoning and City Council meetings. In August 1991, Huffines and Partners,
Inc. submitted a preliminary plat for the referenced property entitled "Riverview Estates". The
property owner at that time was Johnny Thompson. During the review process, there was an
internal memo stating that the plat and the water and sewer layout was in general conformance
with the City's subdivision regulations and design criteria. However, the plat should not be
submitted for approval until issues relating to storm drainage had been resolved. There was no
mention of the floodplain in this memo.
The plat was submitted and went to Planning and Zoning for approval on September 19, 1991.
It was recommended for approval with the stipulations that they include a flagstone entrance and
that a Homeowners Association be created. Subsequent to that meeting, it was presented to the
City Council on October 8, 1991. The staff report that went along with the plat did not make
any mention of floodplain issues. However, during the discussion by City Council there was
conversation about the flooding of the property and also concerns about if the development met
City requirements concerning drainage. However, the plat was approved with only three
stipulations: 1) the flagstone entrance, 2) Homeowners Association, and 3) deletion of alleys.
The motion that approved the plat did not make any mention of floodplain issues.
After the City Council meeting, Gary Sieb sent a letter to Mike Daniel, the engineer for this
development, stating that the plat had been approved with stipulations. Stipulations # 1, 2 and
4 are as presented in Council motion; however, stipulation #3 in Gary's letter states that the
floodplain issue must be resolved prior to final plat filing. Based on conversation between
Johnny Thompson, Jim Witt and myself it appears as though that one particular sentence is what
he is referring to when he states that the preliminary plat should still be valid because that issue
has not been resolved and he had been instructed not to submit the plat until the issue had been
resolved. The Subdivision Ordinance, in effect at that time, states that preliminary plats are only
good for nine months unless the final plat is submitted. There has been no final plat submission
on this particular piece of property.
Some of the issues that really complicate this matter is that when this plat was submitted the
official City of Coppell map in effect, dated October 16, 1991 did not show this tract of land
to be included in the 100-Year Floodplain. However, the City was working on preliminary
FEMA maps and there were memos from Shohre Danesmand stating that the property was in
the floodplain. Based on the map in effect at the time this was originally submitted, it is quite
possible that Mr. Thompson could have completed his development if he would have followed
through and not been subject to the floodplain requirements. Shohre had taken a different
approach in the fact that there were preliminary FEMA maps that were showing this property
to be included in the floodplain with the next revised map. Therefore, she had taken the position
that the property was technically in the floodplain even though it was not shown on the official
map. There were numerous conversations and letters between Shohre and Mike Daniel
concerning floodplain, wetlands, Corps of Engineers, etc. Shohre's final position on this in
November 1991 was that the applicant should submit all the flood studies and request a Letter
of Map Revision from FEMA prior to any development.
The real issue at stake is whether the preliminary plat is still valid. If the preliminary plat is
still valid then we need to decide if there is any vested rights in various things such as payment
of fees, floodplain determinations based on maps in effect at that time, if the property needs to
comply with the Corridor Development Certificate which was adopted in December 1992 and
requires no loss in valley storage, etc. If we determine that the preliminary plat is no longer
valid, then we are back to square one on this development. Which in my mind means we go
back to the preliminary plat submittal and all rules currently in effect in regards to development,
including fees, ordinances, etc. This needs to be resolved as soon as possible.
November 14, 1991
t..E COPY
P.O. Box 478
Coppell, Texas 75019
214-462-0022
Mr. Mike Daniel, P.E.
Nathan D. Maier Consulting Engineers, Inc.
Three Northpark
8800 N. Central Expressway, Suite 300
Dallas, TX 75231
Re: Proposed Reclamation Project
Riverview Estates
Dear Mr. Daniel:
On November 12, 1991, ! received your follow-up letter to our telephone
conversation held on 11-5-91, regarding reclamation of the proposed
Riverview Estates. It came to my attention that said letter did not fully
represent my comments. As a point of clarification, I forward this letter
with my comments concerning your project, which, as minimtult, must be
addressed:
This development must be in full compliance with the City of
Coppell's Floodplain Ordinance #87390.
A wetland determination must be obtained as soon as possible,
to identify existence of any wetlands.
All necessary permits must be obtained from other entities such
as federal (including the Corps of Engineer's (COE) 404
Permit), and state governments, if applicable.
This tract is within the regulatory zone of the Elm Fork of the
Trinity River, and the City is participating in the Trinity
River Corridor Floodplain Management. We recommend this
project to be in compliance with the Corridor Development
Certificate (CDC) manual and criteria· However, according to
our legal council, the CDC permitting process can not be
enforced, since it has not been adopted by the City Council.
I also indicated that in the City-Wide Storm Water Management
Plan, it is proposed that "... no reduction in valley storage
for the 100-year flood (fully developed watershed) be allowed
· . . along Elm Fork of the Trinity River.
Letter to Mr. Mike Daniel, P.E.
November 14, 1991
Page 2
- That the "no loss in valley storage" requirement is not
outlined in detail in the Floodplain Ordinance #87390. Please
note that as per Art. 4C-c, Pg. 24, you must ... demonstrate
with technical data, the impacts on the design base flood
storage capacity of the floodplain for all developments, which
include fill within the floodplain . . ·
- Once you submit all necessary flood study reports and
documents, they will be reviewed according to Ordinance #87390
for compliance. Upon approval, City staff will request a
conditional LOMR from FEMA, prior to issuance of Floodplain
Development/Fill.permit.
- The minimum finished floor of residential lots must be elevated
to a minimum of two (2) feet above the FIS base flood
elevation, or to one (1) foot above the design base flood
(ultimate condition) elevation, whichever is higher.
It is my understanding and as you may know, the City Council is interested
in procuring additional dedicated land for a part site/open space as part
of this development. This is a desirable use of land within the limits of
floodplain.
We look forward to working with you on this project and should you have
any additional questions, please do not hesitate to call me.
M. Shohre Daneshmand, P. E.
Acting City Engineer
MSD/bd
cc: Gary L. Sieb, Director of Planning and Community Services
Don E. Huffines, Huffines & Partners
Gary C. Hendricks, P.E., Shimek, Jacobs & Finklea
RIVERLT
NATHAN D. MAIER
CONSULTING ENGINEERS, INC.
November 5, 1991
!,~ Spofh~,hr~aypell~lv~shm~
Cop~
Re:
Rivervlew Estates
NDM No.: 91-08-075
Dear.Shohre:
The purpose of this letter is to memorialize our telephone conversation of this date regarding the above
referenced project.
Our conversation represented the City of Coppell's formal response to my letter to you, dated October
14, 1991, requesting clarification on the reclamation process for this
site.
During our conversation, you stated that the developer's responsibility includes and, l~' limited__to the
following steps:
1.We must obtain a wetlands determination from the Corps of Engineers (COE). ff the
COE determines that wetlands exist on the site, we must obtain a 404 permit.
2.We must prepare a hydraulic report for submission to the City. The City will forward our
report to FEMA and request a "Conditional Letter of Belief" from FEMA.
3. Upon receipt of the Letter of belief, we will be free to begin reclamaiton work on the site .....
The fill will be placed to an elevaiton which conforms t~t~he City of Coppell's~ninimum.
. ? requirements for streets, and finished floors. '
· . .....
Additionally, you' report_ed...~baL~ld have ._no_.ree~_~lr~slbilitiee relating to valley storage, unmss
mandated by the tOE, and that w~~ed to seek approval for the reclamation from the
Council of Governments.
Please understand that my client intends to proceed with this porject and Incur costs based upon
content of our discussion.
Thank you for taking the time to research thi~ Information and passing it along to us.
Sincerely,
NATHAN D. MAIER
Mike Daniel, P.E.
CMO/rdp
cc: Don Huffinee
Three NorthPark/8800 N. Central Expwy./Suite 300/Dallas, Texas 75231/(214) 739-4741
,NDM
NATHAN D. MAIER
CONSULTING ENGINEERS, INC.
Ms. $1'~_ re ..~2~'feshmand
c~yof~
~lI, Tex~ 7~19 _
Re: ~iew Estams
NDM No.: 91-08-075
Dear Shohre:
We are about to begin our final design on the above referenced project. Please inform us of any and all
of our respensibilities relative to flood plain issues for this propmty.
We are aware of the City's criteria regarding minimum finished fl(xx elevations and minimum elevations
for street paving. We know of no other responsibilities. Enclosed is a copy d what we believe to be the
pertinent FEMA map. As you can see, the subject property does not lie within the FEMA flood plain area.
We had therefore not intended to Involve FEMA in our design process.
We look forward to your timely response so that we may proceed.
Sincerely,
CONSULTING ENGINEERS, INC_~
Mike Daniel, P.E.
CMD/rdp
Three NorthPark/8800 N. Central Expwy./Suite 300/Dallas, Texas 75231/(214) 739-4741
-DOt:,,-
EVALUATION OF iTEM:/
Date of Pb'""'{"E & Z0ni~
Decision of PI~-"inE & Zoni~E Com:
Z) that a hOmeowne~
BUDGET AMT.
AMT +/~ BUDGET '
LEGAL REVIEW BY:"
AGENDA
change request. Ed Thomas of 721 Greenway Drive asked if any consideration were being given
to Greenway Drive not being cut through, stating that he would rather not see any road cut
through to Greenway Drive. There being no other persons who wished to speak, Mayor Wolfe
closed the Public Hearing. Councilman Robertson moved to approve a zoning change request,
Case #PD-120 (Waterside Estates, Phase II), from (SF-9) Single-Family-9, to (PD-SF-9)Planned
Development Single-Family-9, on property located along the north side of Parkway Boulevard
and along the west side of MacArthur Boulevard with the following conditions: 1) detailed plan
on the final plat regarding landscaping; 2) 4-foot wrought iron fence; 3) simplified statement
as to homeowners dues to the homeowners association; 4) the alley be moved from between
Lots 27 and 28 tO between Lots 20 and 21 and that an alley be put in along Lot 35, Block D;
5) that 50% of the houses which back up to Greentree and Meadowglen Circle be single story
homes and that 25% of the houses overall be single story; 6) there be a 2100 square font
minimum house size; 7) an alley be placed in Block E; and, 8) an alley be placed in Block
A, along Lots 1 through 6. Councilman Cowman seconded the motion. The motion carried 7-0
with Mayor Pro Tern Smothermon and Councilmen Weaver, Thomas, Morton, Cowman,
Robertson and Nelson voting in favor of the motion.
Item 16
Consideration and approval of a preliminary plat request for Waterside Estates,
Phase H, on property located along the north side of Parkway Boulevard, and
along the west side of MacArthur Boulevard, at the request of Dan Dowdey
Associates, Inc.
Mayor Pro Tern Smothermon moved to approve the preliminary plat request for Waterside
Estates, Phase II, on property located along the north side of Parkway Boulevard, and along the
west side of MacArthur Boulevard, at the request of Dan Dowdey Associates, Inc with the same
conditions as in Item 15. Councilman Morton seconded the motion. The motion carried 7-0
with Mayor Pro Tern Smothermon and Councilmen Weaver, Thomas, Morton, Cowman,
Robertson and Nelson voting in favor of the motion.
Mayor Pro Tem Smothermon excused himself due to a conflict of interest. A Conflict of
Interest Statement is on file with the City Secretary's office.
Item 17
PUBLIC HEARING: Consideration and approval of a zoning change request,
Case #ZC-532, (Riverview Estates), from (R) Retail, to (SF-9) Single-Family-9,
on property located approximately 320 feet east of Riverchase Drive, and 237 feet
south of Sandy Lake Road, at the request of Huffines and Partners.
Planning and Community Service Director Gary Sieb made a presentation to Council. Concerns
included 1) Landscaped entrance with irrigation to the subdivision off of Sandy Lake Road and
2) Homeowners Association be created to maintain the common open space. Mike Daniel,
representing Huffmes and Partners, was also present to address Council. Mayor Wolfe declared
the Public Hearing open and nsked if there were any persons who wished to speak in favor of
or in opposition to the zoning change request. There being none who wished to speak, the
Public Hearing was closed. Councilman Robertson moved to approve a zoning change request,
Case #ZC-532, (Riverview Estates), from (R) Retail, to (SF-9) Single-Family-9, on property
located approximately 320 feet east of Riverchase Drive, and 237 feet south of Sandy I~lr,.
Road, at the request of Huffines and Parmers. Councilman Nelson __~'x'o__nded the motion. The
motion carried 6-0 with Councilmen Weaver, Thomas, Morton, Cowman, Robertson and Nelson
voting in favor of the motion.
Item 18
Consideration and approval of a preliminary plat request for Riverview Estates
Addition, on property located approximately 320 feet east of Riverchase Drive,
and 237 feet south of Sandy I ~,,- Road, at the request of Huffine~ and Partness.
Planning and Community Services Direct~ Gary Sieb made a present, ion to Council.
Followi~ di~aioa, Couacil ~ St~ff to look at th~ flood plain issues of this propmy
on the property east of this development, and if this development meets city requirements
concerning drainage. Councilman Thomas moved to approve a preliminary plat request for
Riverview Estates Addition, on property located approximately 320 feet east of Riverchase
Drive, and 237 feet south of Sandy Lake Road, at the request of I-Iuffines and Partners with the
following conditions: 1) they include a flag stone or similar enUance with irrigated divider;
2) a homeowners association be formed to maintain common open spaces such as landscaping,
screening fences, etc.; and, 3) no alley behind lots 9-28, Block A. Councilman Nelson
seconded the motion. The motion carried 6-0 with Councilmen Weaver, Thomas, Morton,
Cowman, Robertson and Nelson voting in favor of the motion.
Mayor Pro Tem Smothermon returned to Council.
Item 19 Consideration and approval of a zoning change request, Case #S-1054, from
Light Industrial, to (II-SUP) Light Industrial with a Special Use Permit for a
· tdetrocel Cellular Telephone Communication Tower, on property located east of
Denton Tap Road, and approximately 212' north of Beltline Road, at the request
of Metrocel Cellular Telephone Company.
Planning and Community Services Director Gary Sieb made a presentation to Council. Steve
Dunnaway, representing Metrocel Cellular Telephone Company, was also present to address
Council. Mayor Wolfe declared the Public Hearing open and asked if there were any persons
who wished to speak in favor of or in opposition to the zoning change request. There being
none who wished to speak at this time, Mayor Wolfe closed the Public Hearing (following
discussion of this item, the Public Hearing was left open until October 22, 1991). Charles
Crane of Metrocel Cellular Telephone Company was also present to address the technical issues
of the request. He stated that a 75' to 100' tower is what will be needed. Councilman Nelson
moved to approve a zoning change request, Case #S-1054, from Light Industrial, to (LI-$UP)
Light Industrial with a Special Use Permit for a Metrocel Cellular Telephone Communication
Tower, on property located east of Denton Tap Road, and approximately 212' north of Beltline
Road, at the request of Metrocel Cellular Telephone Company, with the condition that if at any
time this use ceases, all structures and equipment will be removed from the location.
Councilman Weaver seconded the motion. The motion failed 3-4 with Councilmen Weaver,
Robert.son and Nelson voting in favor of the motion and Mayor Pro Tern Smothermon and
Councilmen Thomas, Morton and Cowman voting in opposition to the motion. Following
further discussion, Mayor Pro Tern Smothermon moved to postpone further consideration of this
item until October 22, 1991 with the Public Hearing being left open. Councilman Cowman
seconded the motion. The motion carried 7-0 with Mayor Pro Tern Smothermon and
Councilmen Weaver, Thomas, Morton, Cowman, Robertson and Nelson voting in favor of the
motion.
Item 20 Consideration and approval of a replat request of Northlake Woodlands East #12,
Lot 6.R, Block F, for the puq~nse of combining two lots to allow the construction
of a 6,000 square foot home, on property located north of Beltline Road, and
west of Mockingbird Lane, at the request of Don Tipton Engineers.
Planning and Community Services Director Gary Sieb made a presentation to Council. Mayor
Wolfe declared the Public Hearing open and asked if there were any persons who wished to
speak in favor of or in opposition to the replat request. There being none who wished to speak,
Mayor Wolfe closed the Public Hearing. Councilman Robertson moved to approve a replat
request of Northlake Woodlands East #12, Lot 6-R, Block F, for the purpose of combining two
lots to allow the construction of a 6,000 square font home, on property located north of Beltline
Road, and west of Mockingbird Lane, at the request of Don Tipton Engineers with the condition
that after the underground line (if Staff is comfortable with tho time frame, the line to be
installed by June, 1992) is insialled, that the homeowner of the rezoned lot will be, at that time,
allowed to build a sport court type of structure with a concrete slab and without vertical walls
over the easement wi~x~ut any future engi~ming requiremeats f~om ~ City of Coppell. Mayor
Pro Tern Smothennon seconded the motion; The motion carried 6-1 with Mayor Pro Tm
CITY OF COPPELL
PLANNING DEPARTMENT
STAFF REPORT
RIVERVIEW ESTATES - PRELIMINARY PLAT
P & Z HEARING DATE: September 19, 1991 '"
C. C. HEARING DATE: October 8, 1991
LOCATION: Approximately 320 feet east of Riverchase Drive and 237
feet south of Sandy Lake Road.
SIZE OF AREA: 18.94 Acres of land.
REQUEST:
Approval of a preliminary plat.
APPLICANT:
Huffines and Partners
7001 Preston Road
Suite 222
Dallas, Texas 75205
HISTORY:
No history on this site.
TRANSPORTATION:
Future access wi-Il be gained via Sandy Lake Road and off
Riverchase Drive. Riverchase Drive must be constructed in
its entirety from its existing connection near the
golfcourse, all the way up to Sandy Lake Road.
ANALYSIS:
The preliminary plat as submitted, is in conformance with
City regulations and codes. However, the installation of
Riverchase Drive is of great concern to staff. The
developers of this site (Riverview Estates), Villages at
Riverchase, and Riverchase Estates must resolve how
Riverchase Drive will be installed in its entirety. There
is a section of the future street that is not adjacent to
either development, (see attached map) but it must be
installed prior to either of the developments to ensure
that proper access to each site is provided. Therefore,
staff recommends approval of the preliminary plat subject'
to the installation of Riverchase Drive.
ITEM 17
AL?ERNA? IVES:
1) Approve the preliminary plat as submitted
2) Deny the preliminaryplat as submitted
3) Modify the preliminary plat
ATTAChmENTS:
1) Preliminary Plat
2) Map of development proposals
RVRV I EW. STF
T'LE COPII
TO: Gary L. Sieb, Director of Planning and Community Services
FROM: ~F/M. Shohre Daneshmand, Acting City Engineer~
SUBJECT: Riverview Estates, Preliminary Plat
Floodplain Management
DATE:
October 8, 1991
Gary Hendricks of Shimek, Jacobs & Finklea, representing the City of
Coppell engineering department during DRC meeting, had made Mr. Mike
Daniel of Nathan D. Maier Consulting Engineers, Inc. aware that this
property is within the limits of the 100-year floodplain. It was
indicated to him by Mr. Daniel that this development is part of the
existing Riverchase Reclamation Project.
Please note that it has always been clear to us that a tract of land known
as Johnny Thompson's property is within the 100-year floodplain. (See
attached copy of memo to Greg Jones of Building Inspection, dated
2/25/91). However, the connection was not made between Riverview Estates
and Thompson's property until now.
The above referenced development is within the limits of 100-year
floodplain and shall comply with our Floodplain Ordinance #87390. The
developer must also obtain two (2) permits, being the floodplain
development permit, from the City of Coppell, and a Corridor Development
Certificate (CDC), since this property is within the Regulatory. Zone of
the Trinity River Corridor.
Staff does not have any objection to the preliminary plat as long as the
above comments are addressed prior to the approval of the final plat and
plans.
Please let me know if you have any questions.
cc: Gary C. Hendricks, Shimek, Jacobs & Finklea
RIVER2
Minutes of September 19, 1991
Planning & Zoning Commission
Page 6
Vice-Chairman Green then opened the public hearing and asked for
persons wishing to speak in opposition to the request. There
were none. He then asked for persons wishing to speak in favor
of the request. Those persons speaking were:
Kathy Ingle 200 E. Beltline Road
The public hearing was then declared closed.
Following discussion, Commissioner Cottenmoved to approve case
#5-1054 with the condition that if at any time this use ceases,
all structures and equipment will be removed from the location.
Commissioner Mayo seconded the motion; motion carried (3-1) with
Vice-Chairman Green and Commissioners Mayo and Cotten voting in
favor of the motion, and Commissioner Gross voting in opposition
to the motion.
Item 9: Consider request for a zoning change, Case #ZC-532, (Riverview
Estates Addition) from (R) Retail, to (SF-9) Single-Family-9,
located approximately 320 feet east of Riverchase Drive, and 237
feet southof Sandy Lake Road, at the request of Huffines and
Partners, Inc.
P&Z Coordinator Taryon Bowman introduced the item to , the
Commission.
Mr. Mike Daniel of Nathan Maier Engineers was present to
represent this item before the Commission and answer any
questions.
Vice-Chairman Green then opened the public hearing and asked for
persons wishing to speak in opposition to the request. There
were none. He then asked for persons wishing to speak in favor
of the request. Again there were none. The public hearing was
then declared closed.
Following discussion, Commissioner Cotten moved to approve Case
#ZC-532 with a note that special attention should be given to
the fact that this development is at an important entrance into
the City, during the platting process. Commissioner Gross
seconded the motion; motion carried (4-0) with Vice-Chairman
Green and Commissioners Mayo, Cotten and Gross voting in favor
of the motion.
Minutes of September 19, 1991
Planning & Zoning Com~ission
Page 7
Item 17: Consider request for a preliminary plat of Riverview Estates
Addition, located approximately 320 feet east of Riverchase
Drive, and 237 feet south of Sandy Lake Road, at the request of
Huffines and Partners, Inc.
Mr. Mike Daniel of Nathan Maier Engineers, as well as Mr. Don
Huffines of Huffines and Partners, were present to represent
this item before the Commission and answer any questions.
Following discussion, Commissioner Gross moved to approve the
preliminary plat for Riverview Estates Addition with the
following conditions:
1) that they include a flag stone or similar entrance with
irrigated divider; and
2) that a homeowners association be formed to maintain common
open spaces such as landscaping, screening fences, etc.
Commissioner Cotten seconded the motion; motion carried (4-0)
with Vice-Chairman Green and Commissioners Mayo, Cotten and
Gross voting in favor of the motion.
Item 10: Consider request to vacate a plat of Waterside Estates, Phase I,
located along the south side of Parkway Boulevard, west of
MacArthur Boulevard, at the request of Albert Halff and
Associates, Inc.
P&Z Coordinator Taryon Bowman introduced the item to the
Commission.
Vice-Chairman Green then opened the public hearing and asked for
persons wishing to speak in opposition to the request. There
were none. He then asked for persons wishing to speak in favor
of the request. Again there were none. The public hearing was
then declared closed.
Following discussion, Commissioner Mayo moved to approve the
request to vacate the final plat of Waterside Estates, Phase I.
Commissioner Cotten seconded the motion; motion carried (4-0)
with Vice-Chairman Green and Commissioners Mayo, Cotten and
Gross voting in favor of the motion.
Item 15: Consider request for a final plat of Waterside Estates Addition,
Phase I, located along the south side of Parkway Boulevard, west
of MacArthur Boulevard, at the request of Albert Halff and
Associates.
The City With A Beautiful Future
COPY
P.O. Box 478
Coppell, Texas 75019
214-462-0022
September 9, 1991
Mr. C. Michael Daniel, P.E.
Nathan D. Maier Consulting Engineers, Inc.
Three Northpark
8800 N. Central Expressway, Suite 300
Dallas, Texas 75231
1:~: Riverview Estates/Storm Drainage Design Criteria
Dear Mr. Daniel:
This letter is in response to your request for clarification of the
criteria to be applied to the determination of the starting
hydraulic gradient for the storm sewer outfall of the Riverview
Estates Addition to the City of Coppell. This outfall is proposed
to discharge into the waters of the Elm Fork of the Trinity River.
As you are aware, the City of Coppe11's subdivision ordinance
references the "Design Manual for Storm Drainage facilities",
published by the City of Dallas, as a general guide for design
criteria for storm drainage. The current criteria by Dallas is
that the 100-year water surface elevation of a creek, stream or
other open channel is to be calculated for the time of peak
discharge in the same storm. That water surface elevation shall be
used as the starting hydraulic gradient for the storm sewer system.
The city of Dallas updated drainage design manual (not yet adopted)
revises that criteria to allow for consideration of a coincident
peak determined from an approved flood hydrograph.
Both methods outlined a~ove are open to a wide scale of
interpretation and are subject to a case-bY-Case determination.
For the Riverview Estates Addition (and for all subdivisions whose
storm sewers discharge into the waters of the Elm Fork), it is
recommended that the beginning hydraulic gradient be the 100-year
water surface elevation of Elm Fork, unless engineer documentation
is provided by the developer which confirms justification for a
lower water surface elevation not to be below the 10-year design
frequency. This information should be of sufficient detail to
allow for a determination to be made based on accepted engineering
practices. It is also recommended that the streets, alleys, or
alleys, or finished lots be at a grade as required by the
floodplain management ordinance #87390.
It is our intent to work with you on determining a reasonable
beginning hydraulic gradient for this project based upon sound
engineering practice and judgment. We look forward to working with
you on the project. If you have any questions, please do not
hesitate to call me or Gary Hendricks at (214) 363-1016.
Sincerely, _ ~
Acting City Engineer
cc: Gary Sieb, Director of Planning and Community Services
Gary Hendricks, P.E., Plan Review Engineer
msd/gch/bhj
rivervu.ltr
MEMORANDUM
DATE:
TO:
FROM:
RE:
September 5, 1991
Tayron Bowman, P & Z Coordinator
Gary Hendricks, Plan Review Engineer
River~Estates / Preliminary Plat and Plans
The preliminary plat and the preliminary water and sewer layout plan for
the Riverside Estates prepared by Nathan D. Maier is in general
conformance with the City's subdivision regulations and design criteria.
However, this plat should not be accepted for approval until issues
related to the storm drainage and the beginning hydraulic gradient for the
design of the storm drainage system are resolved. The qualifying note
concerning drainage on the preliminary plat should be removed.
cc: Shohre Daneshmand - Acting City Engineer
riversd.mem