1992-11-12 ' . City of Southlake, Texas
CITY OF SOUTHLAKE
667 N. Carroll Avenue
CITY COUNCIL WORK SESSION
November 12, 1992 6:30 p.m.
MINUTES
COUNCILMEMBER PRESENT: Mayor Gary Fickes; Mayor Pro Tem Rick
Wilhelm; Deputy Mayor Pro Tem Jerry Farrier. Members: Stephen
Apple, Mike O'Brien, Barry Emerson, and Jon Michael Franks.
STAFF PRESENT: Curtis E. Hawk, City Manager; Michael Barnes,
Director of Public Works; Greg Last, Director of Community
Development; Eddie Cheatham, City Engineer; Chris Terry, Assistant
to the City Manager; E. Allen Taylor Jr., City Attorney; and,
Sandra L. LeGrand, City Secretary.
The City Council Work Session was called to order at 7:50 p.m. for
the purpose of discussing Drainage Issues and receiving direction
from the City Council on certain drainage matters.
Staff was asked to categorize various drainage problems within the
City and present to Council in the near future, separating those
with and those without easements.
J. Mallory 1359 Lake View Drive, Cross Timber Hills, Southlake.
Mr. Mallory stated he and an adjoining neighbor are currently
experiencing a drainage problem with an existing ditch. He asked
Council for financial assistance for both a short term and long
term solution to their problems. He explained the ditch is between
two properties and is approximately 150'. During the past two
years, the ditch has become clogged. Mr. and Mrs. J. DeVol, 1361
Lake View Drive, were also present.
Mr. Mallory expressed he has received as estimate to solve the
short term problem from Ragan's Nursery in Southlake, in the amount
of $690.00.
Mayor Fickes asked Mr. Mallory to put his request in writing, and
Council would need to consider this as a consider item on a Regular
Council Meeting.
Mayor Pro Tem Wilhelm suggested the Mayor appoint a Task Force tc
address drainage problems in Emerald Estates Subdivision.
The Work Session was adjourned at 8:30 p.m. The information
presented during the meeting, is attached = he minut-
All
Aar
Mayor Gary F ' ck
,,r` , ,
i ki I. A /�
ATTEST: ' '�i
. �� �.
//f A 4 . . 9
. andra L. LeGrand / : "'
City Secretary 1.-.-;""*.. 1 .
T
DRAINAGE ISSUES
I. Existing Drainage Problems
A. With Easements
Policy Questions: How far does staff pursue correcting
drainage problems in monetary terms?
B. Without Easements
Policy Question: Does the City want to pursue obtaining
drainage easements when existing problems
arise?
II. Development Drainage Problems
A. Easements required downstream
Policy Question: Are all easements downstream of a
subdivision the responsibility of the
developer? If so, how far downstream are
they responsible?
B. Cost participation of drainage improvements
1. On -site improvements
2. Off -site improvements
Policy Question: Should all developments be required to
install drainage improvements if their
development covers less than 60% of the
r t
Drainage Issues
November 12, 1992
Page 2
watershed even if they are eligible to
receive prorata reimbursement.
III. Drainage Maintenance
A. Property owner responsibility of drainage easements
Policy Question: Does the City want the property owners to
maintain drainage easements if it can be
maintained by normal lawn maintenance?
B. City's responsibility of drainage easements
Policy Question: Does the City maintain existing or
proposed drainage easements if the
property owners do not?
IV. City's Liability
Policy Question: Does the City want to implement a
Drainage System Maintenance Plan to
insure all drainage easements are
maintained?
DRAmmisimmumb
ARTICLE 1
GENERAL PROVISIONS
Section 1.01 Purpose
The purpose of this ordinance is to provide for the orderly, safe
and healthful development of the area both within the City and within
it's extraterritorial jurisdiction and to promote the health, safety
and general welfare of the community, and to minimize public and
private losses due to flood conditions. In order to carry out the
purpose hereinabove stated, it is hereby declared to be the policy of
the City to guide and regulate the implementation of all drainage
improvements both within the City and within it's extraterritorial
jurisdiction. This ordinance shall be administered using the following
guidelines:
A. Due consideration shall be given to the City's Master Plan,
Thoroughfare Plan, Land -Use Plan and other developmental guides
recommended by the City.
B. Consideration shall be given to both the currently developed
property and the anticipated development of property in the
future.
C. Protection of the soils, topography, wildlife, vegetation and
other amenities �f the City shall be considered an objective of
this ordinance.
D. Determination of cost participation in any improvements shall
attempt to be reasonable and consistent in their application to
all developments or assessment programs.
Section 1.02 Definitions
A. General Rules: For the purpose of this ordinance, the following
rules shall be applied in constructing, interpreting, or otherwise
defining the terms and provisions hereof:
1. Words used in the present tense shall include the future,
words used in the singular number shall include the plural
number and words used in the plural shall include the
singular.
2. The word "shall" is mandatory and the word "may" is per-
missive.
3. The phrase "used for" shall include the phrases, "arranged
for ", "designed for ", "intended for ", and "occupied for ", and
shall apply exclusively to physical uses.
1 -1
r
B. Definitions: For the purpose of this ordinance, certain words or
terms applicable hereto are defined as hereinafter provided.
Words and terms used in this ordinance, but not defined in this
ordinance shall have the meanings ascribed thereto in the Zoning
Ordinance, The Subdivision Ordinance, or other applicable ordi-
nances of the City.
Benchmark: An elevation reference mark.
"CA" Factor: A multiplicative coefficient achieved by multiplying the
coefficient of runoff "C ", by the area in acres "A" that is tribu-
tary to the point of design.
"cfs ": Cubic feet per second. A measure of the volume of water.
Critical Structures: All drainage improvements outlined in the
Conceptual Drainage Plan (prepared by the City) which are impacted
by a large watershed, and are intended for participatory cost
allocations as determined by the City.
Detention: The detention of stormwater on a site or within a project
shall be interpreted as a temporary restrainment of runoff with
anticipation of normal runoff over an extended period of time.
Development: Any man -made change to improved or unimproved real
estate, including but not limited to, buildings or other struc-
tures, mining, dredging, filling, grading, paving, excavation or
drilling operations.
Development Permit: A permit required before development shall begin
in an area designated as within the limits of the base flood.
Drainage Easement: A delineated portion of land set aside for the
overland or underground transfer of storm water. This area
shall not have any permanent structures, fences, or other
obstacles hindering the safe transfer of water through the
easement.
Drainage Improvements: All elements of a storm drainage system
consisting of streets, alleys, storm sewers, channels, culverts,
bridges, swales, and any other facility through which or over
which storm water flows.
Escrow: Money placed in the possession of the City to accomplish the
purpose set out in this ordinance, including but not limited to
the following: purchase of right -of -way, design and construction
of drainage improvements, curb, gutter, and pavement.
FEMA: Abbreviation for "Federal Emergency Management Agency"
1 -2
"FIRM Map ": A map produced by the U.S. Department of Housing and Urban
Development, which has the purpose of a Flood Insurance Rate Map.
The Federal Emergency Management Agency has delineated both the
areas of special flood hazards and the risk premium zones applic-
able to the community.
Flood: A general and temporary condition of partial or complete
inundation of normally dry land areas from the overflow of inland
or tidal waters, the unusual and rapid accumulation of runoff or
surface waters from any source, or mudslides which are caused or
precipitated by accumulations of water on or under the ground.
Flood, "100 year ": A flood that, on the average, is likely to occur
once every 100 years, (i.e., that has a one - percent chance of
occurring each year). Also referred to as "100 year storm" and as
the "Base Flood ".
Flood plain: The area of land inundated with water over a specified
design storm frequency, typically a 100 year storm.
Floodway: The channel of a river or other watercourse and the adjacent
land areas that must be reserved in order to discharge the base
flood without cumulatively increasing the water surface elevation
more than one foot.
Floodway Map: A map produced by FEMA which delineates the flood
boundary and floodway.
Fort Worth Drainage Manual: The City of Fort Worth Storm Drainage
Criteria and Design Manual.
Freeboard: A factor of safety usually expressed in feet above a flood
level for purposes of flood plain management.
Frequency: The average frequency statistically determined for which it
is expected that a specific flood level or discharge may be
equalled or exceeded.
HEC I Analysis: A computer watershed model developed by the Hydraulic
Engineering Center, U.S. Corps of Engineers, which contains
several methods with which to simulate surface runoff and river -
reservoir flow in river basins and flows in urban areas.
HEC II Analysis: A computer backwater flood model developed by the
Hydraulic Engineering Center which calculates water surface
profiles for steady, gradually varied flows in natural or man -made
channels.
Maintenance: Periodic removal of underbrush, occasional rough mowing,
and no dumping of trash, soil, or other debris. This shall
include general upkeep of the area to prohibit any activity which
may impede the overland flow of storm water.
1 -3
Mean Sea Level: The National Geodetic Vertical Datum (NGVD) of 1929 or
other datum, to which base flood elevations shown on a community's
Flood Insurance Rate Map are referenced.
Mudslide: A general and temporary movement down a slope of a mass of
rock or soil, artificial fill, or a combination of these materials
caused or precipitated by the accumulation of water on or under
the ground.
Retention: The retention of stormwater on a site or within a project
shall be interpreted as a permanent restrainment of runoff with
no anticipation of runoff over an extended period of time.
Ultimate Conditions: The level of development anticipated upon
full development of all land with a watershed. Typically
determined by reference to existing use, existing zoning or
projected land use from the City Land Use Plan, whichever is more
intense. Unless specifically stated otherwise, all storm run -off
calculations required within this ordinance should be based on
ultimate conditions of development.
1 -4
ARTICLE 6
OFF -SITE DOWNSTREAM IMPROVEMENTS
Section 6.01 General
A. General: With the requirements of this Article, the City intends
to allocate the burden of critical off -site improvements between
all the land owners who impact critical structures. The drainage
studies required for each development shall be responsible for
considering their impact on all downstream structures, and cost
participation shall be determined as outlined in this Article.
Section 6.02 Limits of Off -Site Study
A. Conceptual Drainage Plan: The Conceptual Drainage Plan adopted by
the City delineates the major watersheds throughout the City and
highlights critical drainage structures within those watersheds.
B. Limits of Study: The off -site study shall extend either to
the City Limits, the Corp of Engineer's property surrounding
Grapevine Lake, or the Extraterritorial Jurisdiction line where
applicable.
Section 6.03 Responsibility for Off -Site Study
A. First Development: It shall be the responsibility of the first
development equal to or greater than 10% of the watershed flowing
into the lowest point of the tract, by Preliminary Plat, Concept
Plan, or Final Plat, to perform the drainage study to the limits
as described in the previous section.
B. Credit for Cost of Study: The land owner initially respon-
sible for obtaining the Off -Site Study shall be allowed to
credit the cost of the study towards his participation in the
off -site improvements as outlined in this article. The cost of
this study shall be approved by the Director of Public Works. Any
costs deemed unreasonable shall not be credited toward the cost of
off -site improvements.
Section 6.04 Requirements of Off -Site Study
A. Complete Watershed: The Off -Site Study shall include the complete
watershed which drains to the limit of the study as outlined
above. This is regardless of the location of the development
within that watershed.
B. Accuracy Level: The Off -Site Study shall be performed under
the criteria of the Preliminary Drainage Study with the following
additions:
1. All existing drainage structures shall be noted as to
type and size, and current condition.
6 -1
2. All proposed critical drainage structures shall be determined
as to type and size.
3. An accurate acreage breakdown of the entire watershed
and each of the tributary watersheds leading into the
flow line of the main water shed.
C. Cost Determination: Included with the Off -Site Study shall
be an itemized cost estimate of all critical structures within the
watershed downstream. This shall include, but not be limited to,
the following:
1. Cost of removing existing structures where applicable.
2. Cost of repairing or improving existing structures where
applicable.
3. Cost of installing new structures.
4. Cost of improving or maintaining existing open channels.
5. Cost of designing the structures and preparing construction
plans and documents sufficient to obtain competitive bids.
Section 6.05 Off -Site Easement Acquisition
A. Any necessary easements not dedicated by platting shall be
procured by separate instrument and shall be the developer
or property owner's responsibility. If the developer or property
owner cannot obtain a required off -site easement, then the
developer or property owner may request that the City assist in
the acquisition. The developer must make an offer in writing,
based on the fair market value of the easement, to the property
owner from whom the easement is being acquired. In any event, all
costs of obtaining the easement shall be the responsibility of the
developer or property owner and the City must be reimbursed for
any costs incurred.
Section 6.06 Cost Participation for Off -Site Improvements
A. Adjacent Downstream Structures: Drainage structures which
are adjacent to developments shall be paid for as follows:
1. If the development covers 60% or more of the watershed
serviced by the adjacent structure, it shall be the responsi-
bility of the developer to install and pay for the adjacent
structure.
2. If the development covers less than 60% of the watershed
serviced by the adjacent structure, it shall be the responsi-
bility of the developer to install and pay for the adjacent
structure, but the City shall reimburse the developer on a
pro -rata per acre basis when the remaining acreage develops.
This will be on the current cost of the improvements and
6 -2
shall extend for no longer than a five -year period.
B. Other Downstream Improvements: The developer of any tract
of land within a watershed serviced by a critical structure
as outlined in the City Conceptual Drainage Plan shall participate
in the cost of improving that structure on a percentage formula
having a per -acre of watershed coefficient and a land use coeffic-
ient as follows.
1. Within the watershed serviced by said critical structure,
areas shall be delineated showing the more intense land use
of the existing zoning or the proposed land use plan.
2. The "CA" shall be determined for the entire watershed
as a whole to the point of design for the critical structure.
3. The "CA" factor shall be determined for the subject tract.
4. The "CA" factor for the subject tract shall be taken as
a percentage of the "CA" factor for the entire watershed.
This shall be the percentage responsibility of the subject
tract.
5. This percentage shall then be multiplied with the cost
of the critical structure to obtain the dollar amount
of contribution required by the subject tract.
Section 6.07 Construction of Off -Site Improvements
A. Remaining capacity in critical structure: When the critical
structure being impacted by the proposed development still
has capacity to handle the increase in runoff created by the
development, the developer shall not be responsible for the
construction improvements to the structure or replacement
thereof. The developer will be responsible for satisfying
the monetary obligation for participation as outlined in the
previous section.
B. No capacity remaining: Should the proposed development create
runoff which exceeds the capacity of the critical structure, it
shall be the responsibility of the developer to construct the
ultimate improvements needed to said structure.
1. Prior Contributions: The City shall be responsible for
transferring all funds from previous developments contri-
bution to the specific structure to the developer who must
construct said improvements.
2. Future Refunding: The City shall be responsible for procur-
ing additional participatory funds from other developers
within said watershed and transferring these funds to the
developer responsible for constructing the improvements.
This shall only extend for a period of five years from the
6 -3
date of acceptance of the structure by the City inspection
department.
6 -4
ARTICLE 9
MISCELLANEOUS PROVISIONS
Section 9.01 Contingent Warning
A. The degree of flood protection required by this ordinance is
considered reasonable for regulatory purposes and is based ._
on engineering and scientific methods of study. Larger floods may
occur on rare occasions or flood heights may be increased by
man -made or natural causes, such as bridge openings restricted by
debris. This ordinance does not imply that areas outside flood
plain areas or land uses permitted within such districts will be
free from flooding or flood damages.
Section 9.02 Maintenance Issues
A. General: The City considers the issue of maintenance very
important and herein have outlined the responsibilities for
maintenance of all drainage easements and structures.
B. Drainage Easements With No Structures: It shall be the responsi-
bility of the owner to maintain all land contained in a drainage
easement.
C. Drainage Easements With Surface Structures: It shall be the
responsibility of the owner to maintain all land and surface
structures within a drainage easement. This shall include
periodic flushing, hosing, or brooming of surface structures
sufficient to maintain the intended flow of water in the
structure. Maintenance shall not include the replacement of
structures (concrete flumes, etc.) which have deteriorataed
due to age, or which have been destroyed by erosion or other
natural causes. The City shall replace these structures as
funding becomes available at the discretion of the City Manager.
D. Bar Ditches and Culverts: Although these items are typically
found in R.O.W. dedicated to the City, maintenance of these items
shall be the responsibility of the individual land owner. This
shall include all maintenance as outlined in the definitions as
well as periodic grading or earthwork needed to maintain the
intended cross - section of the ditch and to maintain a positive
flow of drainage across the property. Maintenance shall also
include periodic cleaning of culverts to remove all sediment or
other hindrances to the flow of water. Culverts shall be replaced
by the owner should any structural failure in the culvert poten-
tially impede the flow of water.
Section 9.03 Enforcement
A. Development Permit: No development shall be allowed within
the limits of the flood plain until the developer /owner has
received a development permit from the City. This shall include
grading plans and other requirements as outlined by the Director
9 -1
of Public Works.
B. Building Permit: No building permits shall be issued for proper-
ties which have not been analyzed for potential flooding, do not
have applicable floodway or flood plain limits shown, potentially
require a finish floor elevation in excess of that proposed, or do
not fulfill the requirements of this ordinance.
C. Final Plat Filing: The City shall not approve any Plat for
filing in the County Plat Records that does not meet the require-
ments of this ordinance.
Section 9.04 Modifications and Variations
A. Compliance: Where the Council finds that compliance with these
regulations would cause unusual hardship or extraordinary diffi-
culties because of exceptional and unique conditions of access,
location, shape, size, drainage, or other physical features of the
site, the requirements may be modified to mitigate the hardship,
provided that the public interest is protected and the development
is in keeping with the general spirit and intent of this
ordinance.
1. This section shall not be interpreted to permit the develop-
ment of land which is inherently unsuitable for the use
proposed.
2. Any modification will not have the effect of preventing
the orderly subdivision of other land in the area in
accordance with the provisions of this ordinance.
B. Discretion of Council: At the discretion of the Council, the
normal standards and requirements of this ordinance may also be
modified in the case of a Planned Unit Development. Such depar-
tures from the standards specified may be made only when the
Council finds that the plan provides for convenience and safe
access, adequate space for recreation, and provision for light and
air, and offers all essential utility services and necessary
public and other facilities, an is in conformance with all
provisions of the City Code which specifically apply to Planned
Development.
Section 9.05 Violations:
A. Fines: Any person, firm, corporation, agent or employee thereof
who violates any of the provisions of this ordinance shall be
guilty of a misdemeanor and upon conviction thereof shall be fined
not to exceed Two Thousand Dollars and No Cents ($2000.00) for
each offense. Each day that a violation is permitted to exist
shall constitute a separate offense.
B. Injunctions: The City shall have the right to institute an
action in a court of competent jurisdiction to enjoin the
9 -2
violation of any provision of this ordinance within it's municipal
boundary or within its extraterritorial jurisdiction, and this
remedy shall be in addition to any penal provision in this
ordinance or in the Code of the City of Southlake.
Section 9.06 Severability of Provisions:
A. It is hereby declared to be the intention of the City Council of
the City that any word, phrase, clause, sentence, paragraph,
section or part in or of this ordinance shall be severable.
B. If any court of competent jurisdiction shall judge any word,
phrase, clause, sentence, paragraph, section or part in or
of this ordinance to be invalid, such judgement shall not affect
any other word, phrase, clause, sentence, paragraph, section or
part in or of this ordinance not specifically included in said
judgement.
C. If any court of competent jurisdiction shall judge invalid
the application of any provision of this ordinance to a particular
property, building, or other structure, which judgement shall not
affect the application of said provision to any other property,
building, or structure not specifically included in said judge-
ment.
Section 9.07 Conflicting Ordinances
A. This Ordinance shall be and is hereby declared to be cumulative of
all other ordinances of the City; and this Ordinance shall not
operate to repeal or affect any of such other ordinances except
insofar as the provisions thereof might be inconsistent or in
conflict with the provisions of this Ordinance, in which event
such conflicting provisions, if any, in such other ordinance or
ordinances are hereby repealed.
Section 9.08 Liability Disclaimer:
A. General: All of the regulations provided in this Ordinance
are hereby declared to be governmental and for the health,
safety and welfare of the general public. Any member of the
City Council or a City Official or employee charged with the
enforcement of this Ordinance, acting for the City of Southlake in
the discharge of his duties, shall not thereby render himself
personally liable; and he is hereby relieved from all personal
liability for any damage that might accrue to persons or property
as a result of any act required or permitted in the discharge of
his said duties.
B. Professional Liability: The Professional Engineer responsible for
preparing the drainage study shall retain liability for said
drainage study, regardless of any action taken by the City or the
City's Engineer concerning the study.
9 -3