Item 6HCITY OF
SOUTH LAKE
MEMORANDUM
August 29, 2012
To: Honorable Mayor and City Council
From: Shana Yelverton, City Manager
Subject: Ordinance No. 1030: Storm Water Master Plan
Action
Requested: Conduct a public hearing and consider 2n reading approval of the proposed
Southlake 2030 Storm Water Master Plan.
Background
Information: The Southlake 2030 Plan is the city's guide to determine the community's
goals, aspirations and resource allocations. The Southlake 2030 Plan consists
of multiple elements; the Water, Waste Water, Storm Water Plan is one of
these elements. The Southlake 2030 Water, Waste Water, Storm Water
Committee has recommended that each component of this plan be adopted
separately. The Planning and Zoning Commission made a favorable
recommendation on the storm water plan component at their June 19, 2012
meeting. This completes the Water, Waste Water, Storm Water Plan element
for the Commission.
The City of Southlake contracted with Neel- Schaffer /Cheatham & Associates to
develop the Water, Waste Water and Storm Water Plan. These Plans will assist
the City of Southlake by identifying and prioritizing infrastructure that will require
improvements. To develop the plan, the consultants utilized previous reports
and studies. Neel- Schaffer /Cheatham & Associates also met with Southlake
officials and staff and performed limited site visits to verify data and better
understand the priorities of the City of Southlake. Existing population and
growth data from the North Central Texas Council of Government (NCTCOG)
was also used, along with data from previous engineering studies, reports and
designs performed for the City.
The primary purpose of the storm water master plan is to analyze new, re-
constructed drainage facilities to develop a tiered priority list of drainage
structure improvement projects to further reduce the possibility of structure
(building) flooding and to reduce the number of instances that the City's main
thoroughfares and arterials are blocked by water overtopping the roads and
streets.
Financial
Considerations: Adopting the plan in FY 2012, provides staff and Council the ability to use the
plan as a guide for funding recommendations for FY 2013.
Strategic Link: The Storm Water Master Plan relates to corporate objectives B5 — Improve
performance of delivery and operational processes and F2 — Invest, provide
and maintain high quality public assets.
Citizen Input/
Board Review: All meetings of the Southlake 2030 Water, Waste Water, Storm Water
Committee are open to the public. The committee held two (2) public meetings
(April 24 and May 29 2012) to discuss, review, and develop storm water plan
recommendations. In addition, a SPIN meeting was held June 25 2012 for
the Storm Water Master Plan. The SPIN summary report is included as
Attachment "C.
A public hearing was held for this item at the Planning & Zoning Commission
meeting July 19, 2012.
Planning & Zoning
Commission: Recommended Approval (6 -0) July 19, 2012.
City Council: Approved 1s' Reading on Consent (6 -0) August 21, 2012.
Legal Review: None.
Alternatives: Recommend modifications to the proposed Storm Water Master Plan or
approve the Storm Water Master Plan as presented.
Attachments: (A) Ordinance 1030
(B) Southlake 2030 Storm Water Master Plan
(C) SPIN Meeting Summary Report
ORDINANCE NO. 1030
AN ORDINANCE ADOPTING THE STORM WATER MASTER
PLAN AS AN ELEMENT OF THE SOUTHLAKE 2030 PLAN,
THE CITY'S COMPREHENSIVE PLAN UPDATE.
WHEREAS, a Home Rule Charter of the City of Southlake, Texas, was approved
by the voters in a duly called Charter election on April 4, 1987; and,
WHEREAS, the Home Rule Charter, Chapter XI requires an update to the City's
comprehensive plan elements every four years,
WHEREAS, the City Council recognizes that the Storm Water Master Plan is an
element of the Southlake 2030 Plan, the City's Comprehensive Master Plan,
WHEREAS, the City Council has determined that the Storm Water Master Plan
complies with the Southlake 2030 Vision, Goals, & Objectives,
WHEREAS, the City Council has deemed that the Storm Water Master Plan has
been formulated with adequate public input,
WHEREAS, the City Council has deemed that the recommendations in the Storm
Water Master Plan herein reflect the community's desires for the future development of
the City,
WHEREAS, the City Council has determined it is in the best interest of the
public's health, safety and welfare to establish storm water management requirements
for city residents and businesses,
NOW, THEREFORE, BE IT ORDAINED BY THE CITY COUNCIL OF THE CITY
OF SOUTHLAKE, TEXAS, THAT:
Section 1. All of the findings in the preamble are found to be true and correct and the
City Council hereby incorporates said findings into the body of this
ordinance as if copied in its entirety.
Section 2. The statements in `Exhibit 1' are hereby adopted as the Storm Water
Master Plan of the Southlake 2030 Plan.
Section 3. The different elements of the Comprehensive Master Plan, as adopted
and amended by the City Council from time to time, shall be kept on file in
the office of the City Secretary of the City of Southlake, along with a copy
of the ordinance and minute order of the Council so adopting or approving
the same. Any existing element of the Comprehensive Master Plan which
has been heretofore adopted by the City Council shall remain in full force
until amended by the City Council as provided herein.
Section 4. This ordinance shall be cumulative of all provisions of ordinances of the
City of Southlake, Texas, except where the provisions of this ordinance
are in direct conflict with the provisions of such ordinances, in which event
the conflicting provisions of such ordinances are hereby repealed.
Section 5. It is hereby declared to be the intention of the City Council that the
phrases, clauses, sentences, paragraphs and sections 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 6. The City Secretary of the City of Southlake is hereby authorized to publish
this ordinance in book or pamphlet form for general distribution among the
public, and the operative provisions of this ordinance as so published shall
be admissible in evidence in all courts without further proof than the
production thereof.
Section 7. This ordinance shall be in full force and effect from and after its passage
and publication as required by law, and it is so ordained.
PASSED AND APPROVED on the 1st reading the 21 day of August, 2012.
MAYOR
ATTEST:
CITY SECRETARY
PASSED AND APPROVED on the 2nd reading the day of , 2012.
MAYOR
ATTEST:
CITY SECRETARY
APPROVED AS TO FORM AND LEGALITY:
CITY ATTORNEY
DATE:
ADOPTED:
EFFECTIVE:
CITY OF SOUTHLAKE
CRITICAL DRAINAGE STRUCTURES UPDATE
2012
Background and History
The City of Southlake has undergone significant growth over the past twenty to thirty years. The
City's population has increased from around 2,800 in 1980 to over 26,500 in the 2010 census,
during which time many new subdivisions and commercial entities have been constructed. With
such a rapid rate of development, the City's drainage patterns and storm water runoff have been
significantly affected. This is evidenced by the street crossings that are occasionally overtopped
during intense rainfall events.
Previous City officials and staff recognized the problems associated with building in and
adjacent to creeks, streams and floodplains; such that there are very few homes and businesses
(buildings) that are subject to being flooded in Southlake. Furthermore, most of the City's roads
and streets constructed in the last twenty years generally allow for the passage of this increased
runoff without flooding adjacent existing, or future, building construction. However, there are
some drainage structures and road crossings that are several years old (our site visits noted that
there are a few Works Progress Administration (WPA) drainage structures still being utilized
that were built in the 1930's and 1940's), such that when these crossings are overtopped,
accessibility is compromised resulting in lengthy delays due to detouring traffic around the
blocked street(s) during heavy rainfall events. During heavy flooding events, the overtopping at
these crossings may result in safety issues with the potential of cars being washed off the road or
stalling out at the crossing location.
There are three TxDOT routes in Southlake, Hwy 114, FM 1709 ( Southlake Boulevard) and FM
1938 (Davis Boulevard) that all generally have been or are being reconstructed or improved,
which benefits the City since TxDOT is responsible for most of the expense of these projects. A
noted difference is that TxDOT designs their culverts and bridges for the 50 -year storm, not the
100 -year, which is the preferred City standard. Drainage improvements at these locations would
be a TxDOT initiated and funded project. Since these projects would not be City directed capital
improvement projects and due to the difference in criteria, the TxDOT crossings were not
reviewed in this report. Furthermore, residential and local streets were not considered in this
report unless there was a history of repeated flooding events or there was a noted maintenance
situation that requires attention.
Proiect Scone
Aware that they still had some street overtopping problems, the City had previously initiated
reviews of the critical drainage crossings in Southlake. In 1995, Cheatham & Associates
developed the "Engineering Report Covering Drainage Study and Analysis at Critical Drainage
Structures in the City of Southlake ", in which they reviewed 27 critical crossings. In April of
1998, the "Preliminary Drainage Master Plan Phase I" was presented by Freese and Nichols,
Inc., which included the review of 53 road crossings /drainage problems (including the review of
a few residential streets). In 2007, KSA Engineers, Inc. developed a "Preliminary Drainage
Master Plan Phase II ", expounding upon the Freese and Nichols report, completing full
hydrologic and hydraulic analysis for 24 road crossings. The "Preliminary Drainage Master
Plan" did not cover all of the local drainage problem areas of the entire City, but primarily dealt
with the critical drainage crossings in Southlake.
These reports identified and ranked the most critical locations on the eight (8) major creeks
within the City, but they did not all contain the same number of locations, did not contain the
same locations, and did not have the same priorities. As could be expected, by the time the 2007
report was finalized, some of the proposed improvements identified in the first two reports had
been constructed. Also, in 2012, additional projects have been constructed or are under
construction. The City of Southlake contracted with Neel- Schaffer / Cheatham & Associates to
review these previous reports and studies. The primary purpose is to analyze new, re- constructed
drainage facilities to develop a tiered priority list of drainage structure improvement projects to
further reduce the possibility of structure (building) flooding and to reduce the number of
instances that the City's main thoroughfares and arterials are blocked by water overtopping the
roads and streets.
CITY OF SOUTHLAKE
CRITICAL DRAINAGE STRUCTURE
REPLACEMENT PROGRAM
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CITY OF SOUTHLAKE
CRITICAL DRAINAGE STRUCTURE
REPLACEMENT PROGRAM
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REPLACEMENT PRIORITIES
13 SOUTH LAKE
SPIN MEETING REPORT
CASE NO. Ordinance No. 1030
PROJECT NAME: Storm Water Master Plan — Southlake 2030
SPIN DISTRICT: Citywide
MEETING DATE: June 25, 2012; 7:00 PM
MEETING LOCATION: 1400 Main Street, Southlake, TX
Training Rooms 3A — 3B
TOTAL ATTENDANCE: Ten (10)
• SPIN REPRESENTATIVE(S) PRESENT: None
• CONSULTANT(S) PRESENT: Lynn Hilburn, Derek Cheatham; Neel Schaffer /
Cheatham & Associates
• STAFF PRESENT: Bob Price, Director of Public Works; Steve Anderson, Civil Engineer;
and Lorrie Fletcher, Planner I
STAFF CONTACT: Steve Anderson, Civil Engineer (817)748 -8101; sanderson @ci.southlake.tx.us
EXECUTIVE SUMMARY
The Southlake 2030 Water, Waste Water & Storm Water Committee has finished its
work on the storm water element of this plan and has made the recommendation that
City Council consider approval of the three elements (1: water; 2: waste water and 3:
storm water) separately. As such the storm water element has been completed and is
ready for formal approval. Adopting the plan in FY 2012 provides staff and City Council
the ability to use the plan as a guide for funding recommendations for FY 2013.
• The primary purpose of the current study is to analyze new, re- constructed drainage
facilities to develop a tiered priority list of drainage structure improvement projects to
further reduce the possibility of structure (building) flooding and to reduce the number of
instances that the City's main thoroughfares and arterials are blocked by water
overtopping the roads and streets.
• Presentation outline:
• Background and History
• Studies
• Drainage Basins
• Improvements and Funding
CITY OF SOUTHLAKE
CRITICAL DRAINAGE STRUCTURE
REPLACEMENT PROGRAM
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REPLACEMENT PRIORITIES
QUESTIONS / CONCERNS
• Why do you need three times the size of the box culvert on Dove & Carroll? Didn't you
know it would not be sufficient?
o The existing culvert is a very old structure. We have updated knowledge
regarding flooding.
• The detention ponds are all full; how can they hold additional water if heavy rain comes?
o Detention ponds today are engineered to hold 2 -10 -100 year storms. We haven't
been able to retro -fit older structures. Studying storm water and drainage is an
art & science using statistical chance of occurrence.
• How much rainfall is a 2 -10 -100 year storm?
• A 100 -year is 10 inches per hour
• A 25 -year is 7 inches per hour
• A 2 -year is 5 or 6 inches per hour
• There are bar ditches north of Dove on Carroll. They were built after the last study was
done. We never see more than 2 inches of water. It is very hard to mow and is a safety
hazard. Can anything be done? Director Price offered to meet with these property
owners to discuss options.
SPIN Meeting Reports are general observations of SPIN Meetings by City staff and SPIN Representatives. The report is neither
verbatim nor official meeting minutes; rather it serves to inform elected and appointed officials, City staff, and the public of the issues
and questions raised by residents and the general responses made. Responses as summarized in this report should not be taken
as guarantees by the applicant. Interested parties are strongly encouraged to follow the case through the Planning and Zoning
Commission and final action by City Council.