HomeMy WebLinkAbout539 03-14-1978ORDINANCE NO. 539
AN ORDINANCE REVISING A PORTION OF THE CITY OF
EULESS, SUB - DIVISION RULES AND REGULATIONS
PERTAINING TO METHOD OF MEASURING THE DISCHARGE
OF STORM DRAINAGE WATER, DRAINAGE FEATURES AND
POLICIES, OPEN DITCHES AND CHANNELS, AND OFFSITE
DRAINAGE: PROVIDING A SEVERABILITY CLAUSE; AND
PROVIDING AN EFFECTIVE DATE.
NOW, THEREFORE, BE IT ORDAINED BY THE CITY COUNCIL OF THE CITY
OF EULESS, TEXAS:
Section 1. Section 100 of the City of Euless's sub - division rules and
regulations, originally enacted as Euless Ordinance #148 and
being appendix "B" of the Euless Code of Ordinances, as amended, is
herewith and hereby amended in its entirety to hereafter be and read
as follows:
Section 100. Method of Measuring.
The determination of design discharge of storm drainage water shall
be accomplished in accordance with the following criteria:
(1) The Rational Method (Q = CIA) shall be used on small water
sheds of 750 acres or less.
(2) Unit hydrograph techniques shall be used for areas greater
than 750 acres.
The technique and data to be used for the determination of the
design discharge shall be approved by the City Engineer prior
to the completion of calculation. A complete set of all
detailed calculations must be submitted to the City Engineer
for approval prior to the completion of the plans for the
drainage system.
The design flow shall be based on a five year return frequency except
for bridges, culverts, underpasses, and open ditches. For the latter,
storm drainage design flow shall be based on a 25 year return frequency
storm.
The intensity and duration of the rainfall shall be based on
Technical Paper No. 40 of the Weather Bureau of the United States Department
of Commerce, for the various frequencies.
The coefficient of runoff to be used in the calculations shall be as
follows:
Business areas, 0.95.
Industrial areas, 0.95.
Multifamily, 0.65.
Residential areas, 0.50.
Park areas and permanent open space, 0.35.
The coefficient of runoff for undeveloped land shall be the appropriate
coefficient for the ultimate land development as shown on the Future Land
Use Map of the latest City Master Plan.
The time of concentration is defined as the longest time that will be
required for a drop of water to flow from the upper limit of the drainage
area to the point of concentration. Time of concentration is a combination
of the inlet time and the time of flow in the storm drainage facility. Inlet
time is composed of overland flow time plus the time of flow in the gutter
required to reach the inlet. In calculating gutter time the following are to
be assumed to be gutter velocities:
Slope of Gutter
0.4%
1.0%
2.0°%
3.0%
4.0%
5.0%
6.o%
8.0%
10.0°%
Assumed Velocity
(feet /second)
1.4
2.2
3.1
3.8
4.3
4.9
5.3
6.1
6.9
The minimum inlet times of concentration are shown below:
Parks and permanent open areas, 20 minutes
Residential areas, 15 minutes
Multifamily, Business and Industrial, 10 minutes.
In cases where it is evident that the actual time of concentration is
less than that indicated above, a shorter time of concentration should be
used.
Section 1. Section 103 of the City of Euless's sub - division rules and
regulations originally enacted as Euless Ordinance #148 and
being appendix "B" of the Euless Code of Ordinances, as amended, is herewith
and hereby amended in its entirety to hereafter be and read as follows:
Section 103. Drainage Features and Policies
a. The three basic types of drainage features are as follows:
1. Closed systems.
2. Reinforced Concrete Lined Channels.
3. Natural Channel.
b. Water in excess of what gutters can carry with a maximum depth of
two inches below the top of crown shall be handled in storm sewer
pipe, or shall be handled in open ditches not in the street right -
of -way. Capacity of storm sewers and ditches shall be calculated
by Kutter's or Manning's formula or other approved methods. Storm
water runoff shall be carried in a storm sewer pipe when either of
the following apply:
1. The runoff can be carried in a pipe of 48" in diameter or
smaller; or
2. Where it is necessary for the protection of adjacent facil-
ities that the storm water be carried in an enclosed facility.
Headwalls shall be constructed at the outfall of all storm
systems.
c. Reinforced concrete lined open channels should be used when the
criteria outlined in Section 103 b.1. above is exceeded:
1. Reinforced concrete lined channels shall conform to the
following:
(a) Channels draining an area with a "CA" factor of 250 or less
shall be lined with reinforced concrete in a manner which
will contain the design frequency storm plus one foot of
freeboard within the concrete lining.
(b) Channels draining an area with a "CA" factor of more than
250 but less than 500 shall be concrete lined to contain
the runoff from a five year return frequency storm with the
balance of the required design frequency storm contained
within grassed slopes no steeper than three horizontal to
one vertical and with a minimum of one foot freeboard.
(c) Channels draining an area with a "CA" factor of more than
500 shall be governed by criteria designed for the individ-
ual situation.
d. Channels may be preserved when criteria in Section 103 c.1.(c) is
met or when the developer desires to preserve the natural channels
within his addition for purposes of aesthetics and /or open space
and when approved by the City according to the procedure pre-
scribed for plat approval. The following criteria shall apply
when it is desirable to preserve natural channels.
1. An application for preservation of a natural channel shall
be submitted through the Director of Planning and Development
for review by the City of Euless a minimum of twenty -one days
prior to the approval of the preliminary plat. This appli-
cation shall contain the following information furnished by
the developer:
(a) Topgraphic, hydrologic and hydraulic information
sufficient to properly evaluate the proposal.
(b) When the natural channel to be preserved is one which
has had a Flood Plain Information report prepared by the
Corps of Engineers or other governmental agencies, the
identified 100 year return frequency storm shall be
shown to the extent that it affects the property in the
application. In addition, it shall be demonstrated that
the proposed improvements will comply in all respects
with the criteria outlined in Section 1910 of the
National Flood Insurance Regulations as amended pro -
mologated by the Federal Insurance Administration.
2. When the drainage feature meets the criteria outlined in
Section 103 c.1. (a) or (b) the proposed improvement shall be
constructed with a reinforced concrete pilot channel not less
than six feet in width and having at least eight inch vertical
curbs and a depressed invert with a minimum of transverse
slope of two - thirds inch per foot. The remainder of the
channel shall consist of earthen side slopes with proper
vegetative cover on slopes no steeper than two horizontal to
one vertical below the elevation required for the design fre-
quency storm and three horizontal to one vertical above.
In special cases approved according to the procedure prescribed
for plat approval, large single tract developments may be
governed by criteria designed for the individual situation.
Cases of this nature shall be considered only where the
applicant demonstrates substantial preservation of aesthetics
and /or open space. The mere reduction of development costs
will not be considered as justification for this variance. A
perpetual maintenance agreement shall be provided in accordance
with Sec. 103 d.3.(e) to include all maintenance responsibility
for the faci 1 i ty.
3. All channels meeting the criteria of Section 103 d, shall
also meet the following criteria:
(a) All land having an elevation below the twenty -five year
return frequency flood elevation shall be contained
within an easement dedicated to the public for the purpose
of providing drainage. The twenty -five year return fre-
quency storm shall be determined on the basis of a fully
developed watershed according to the latest available
master plan.
(b) All channel improvements such as reshaping, realignment,
etc., shall be protected with sodding, back sloping,
cribbing, and other bank protection designed and con-
structed to control erosion from the twenty -five year
return frequency storm.
(c) An analysis shall also be made to determine the limits of
the 100 year return frequency flood. A flowage easement
shall be dedicated to limit the construction of any
structures in the area bounded between the 100 year and
25 year return frequency storms as indicated above. The
term structure shall be construed to include any and all
types of fences, portable buildings or any manmade device
which could be construed to be an obstacle to the flow of
water.
(d) The following velocity controls shall be applied to
channels with earthen banks:
(1) Unlined banks in clay soil with grass cover -
8.5 fps.
(2) Unlined banks in sands or silty soil with grass
cover - 5.0 fps.
(e) A perpetual maintenance agreement in form prescribed
by the City of Euless shall be executed by all parties
owning any interest in the property abutting upon,
adjacent to, or included within such channel and flow-
age easement provided for in Section 103(d) hereof.
Such perpetual maintenance agreement shall be filed of
record and shall establish an affirmative burden, charge
and duty on the part of all existing and future parties
owning any interest in the property abutting upon,
adjacent to, or included within such channel and flow-
age easement for the maintenance of the channel and
flowage easement with regard to vegetation, erosion
control, and the control of trash and debris. The
right, without a duty to do so, shall be given the
City of Euless to enforce such perpetual maintenance
agreement, and, if it so elects, to perform necessary
maintenance, the pro -rata cost of which may be charged
as a priority lien and assessment against the property
and the owners thereof abutting upon, adjacent to, or
included within such channel and flowage easement.
Section 1. Section 109 of the City of Euless's sub - division rules and regu-
lations, originally enacted as Euless Ordinance #148 and being
appendix "B" of the Euless Code of Ordinances, as amended, is herewith and
hereby amended in its entirety to hereafter be and read as follows:
Section 109. Open Ditches and Channels
All open ditches in subdivisions that are used to carry surface runoff
shall be lined in accordance with the criteria outlined in Section 103.
The required improvement shall extend across the entire areas of each
subdivision being developed and offsite improvements shall be as re-
quired by Section 112. Lining of drainage ditch floors shall be done
with six inches thick or thicker concrete. Walls shall be a minimum of
four inch thick concrete sloped not steeper than one foot vertically to
one and one -half feet horizontally. All concrete slabs are to be rein-
forced with a minimum of ten inches by ten inches by ten gauge by ten
gauge wire mesh and provided with proper weep holes and other pressure
relief measures.
All open channels shall have a minimum bottom width of four feet. The
height of the lining shall be adequate for the calculated depth necessary
to meet the requirements of Section 103. Side slopes of the channel above
the lining shall not be steeper than one foot vertical to two feet hori-
zontal.
IV.
Section 1. The City of Euless's sub - division rules and regulations, originally
enacted as Euless Ordinance #148 and being appendix "B" of the
Euless Code of Ordinances, as amended, is herewith amended by the addition of
the following new Section 112, which from and after the effective date hereof,
shall be and read as follows:
Section 112. Offsite Drainage
a. The owner or developer of property to be developed shall be respon-
sible for all storm drainage flowing on his property. This respon-
sibility includes the drainage directed to that property by prior
development as well as drainage naturally flowing through the property
by reason of topography.
b. Adequate consideration shall be given by the owner in the develop-
ment of property to determine how the discharge leaving the proposed
development will affect downstream property.
C. In all new developments where storm water runoff has been collected
or concentrated, it shall not be permitted to drain onto adjacent
property except in existing creeks., channels or storm sewer unless
proper drainage easements or notarized letters of permission from
the affected property owner are provided.
d. The subdivider shall pay for the cost of all drainage improvements
required for the development of his subdivision, including any
necessary offsite channels or storm sewers and acquisition of the
required easements with the following exception: If the owner is
unable to acquire the necessary offsite easements, he shall provide
the City with documentation of his efforts, including evidence of a
reasonable offer made to the affected property owner. Upon such a
written request for assistance, the City shall attempt to acquire
these easements through negotiations. In certain situations the
City may consider condemnation. In any case, all costs associated
with the acquisition of these easements shall be paid by the owner.
e. Where it is anticipated that additional runoff incident to the
development of the subdivision will overload an existing downstream
drainage facility, whether natural or manmade, and result in haz-
ardous conditions, the Planning Commission may withhold approval
of the subdivision until appropriate provision has been made to
accomodate the problem, and plans shall be provided which include
all necessary offsite improvements including storm sewer systems,
channel grading, driveway adjustments, culvert improvements, etc.
V.
Section 1. That it is hereby declared to be the intention of the City
Council that the sections, paragraphs, sentences, clauses and
phrases of this ordinance are severable, and if any phrase, clause, sentence,
paragraph or section of this ordinance shall be declared unconstitutional by
the valid judgment or decree of any court of competent jurisdiction, such
unconstitutionality shall not affect any of the remaining phrases, clauses,
sentences, paragraphs and sections of this ordinance, since the same would
have been enacted by the City Council without the incorporation in this
ordinance of any such unconstitutional phrase, clause, sentence, paragraph
or section.
Section 2. This Ordinance shall become effective immediately upon second
and final passage.
PRESENTED AND GIVEN FIRST READING at a regular meeting of the Euless
City Council on the 28th day of February, 1978; by a vote of 5 ayes,
0 nays and 0 abstentions.
GIVEN SECOND READING, PASSED AND APPROVED at a regular meeting of
the Euless City Council on the 14th day of March 1978; by a vote of
5 ayes, 0 nays and 0 abstentions.
;2:7 S. S2 49-1�
Harold Samuels, Mayor
ATTEST:
Della Houy, City Secret
APPROVED:
M. Robe%itMM Fa.r11 an CT ,
City Attorney