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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 -X 95 -20 - �� -_ 98 -X 07 -X 98 -01 �` 98 -19 07 -X \98 07 -07 07 -X 95 -24 95 -26 98 -X i BIG BEAR CREEK 98 -X 95 ` ° 07 -X -21 07 -X 95 -22 95 -23 98 X 98 -X 98 -26 07 -X 07 -X 07 -06 PREVIOUS STUDIES /PROPOSALS T N U IT E o T Y c o Y o 0 > - m? a m a E E o 3 o E c E >> a a 3 a o o o a o > c o > - 3> -° o o m> o N ° o Q Q> > n a - o> E v a a a a o 3 0> N o o a 3 w o a 3 Y a o a T ° o Z 3 a c a n T 0 3 a -_ - > 3 a - m o o r > E 3 m o a _� 0 o E °-' m o m n o 0 _ 0 - o .� o° = ow 10 0 U 3 o f n S E> r c Y o o f Y _ v a s' o E o °' c O o o a`o - o v o - E Y' E r m. a o - 0 a 3 c °- 3 > v� m -Oo ° o 3 3 O vi > E a vi -° o '° Y -° m vi o o m o - a o o > m o o E m a u u m ¢ -° - w o - - m o w o w o > m >, w o N w - o w _ o a `3 � o a o -° a 3 i ° a i o f - o o E i i s o I s i J o o '3 s¢- `m F o E o o u` 0 0 0 0 0 o a o u o v o .3 0 Z o° s -O L u m m t uo o m tj E m E E E o _ E n n d o u o o o u o o m o - - - m E ° u u Y > ° _ > m E m m > > m m > > > > - 0 3- a - O c= 3- E - - O c x 3 - a 3 a c x 3- o- -° c m -° c -° c 3- o- -° c =, o m o u o '° m 3" - o o c 1 ° - u m N - m o Y u s m '° u m o.. - m° m a u -°- m °' s° u a u °° m - a u H m° a u s° - a u- a u m o u m u mo m u - 1° x a 2 N K= -a ° ° x> m m N= o °- m u Lo c o o m -a° N o °. m o o O == -a ° = O O N o n m a u F N= U °. m K= U - °- m r- - = o o N x n m a u F x K l7 m '^ a X K l7 o a c u t o o- o o s l7 U o c o o _rx K l7 a c o a K l7 o 0 0 o o,� - °° _rx K l7 c o x K l7 a c o ° s 1 D -m o 0 o ,� ti - o 0 o a c ro c '_^ a m. u s u u .n o m O O N a � o N m m � o u s u u v .h u s u +n o N a m O o u s u .n c '_^ a M u s u .n c '_^ a m o u s u u +"n o a u s u .n o F a N u s u .n m o^ o o F a O u s u u ."n E '^ o 0 °- 0 ro 0 o 0 o 0 ° 0 0 ° 0 c o u ° w o a E u m x u m u m x m u m x' CN x m u m m u m m x v w Y o 0 v F o Lo w - ti m - ti m c o o m o w 0 0 0 r c 0 o c w 0 o 0 c 0 0 ro 0 0 0 > u V r w r w m a u u m r U m u m K _ u u m L. 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H O O H O O N N o .b v. m O C o v �° m° v. — p o N o °- H O o v i s a T ,� 3 v m H— �. C o 0¢ a ti o .y u .n °�' c n o u s u a '^ m Z V c V �n. u s u .n a o u s u +"n a u s u .n u x 0 z u u °�' m u s u _ N 0 u s u .n E o o u 0 0 ° I o 0 0 ° ro 0 O ° 0 ° o ° O I O ° m = r v Y o 0 u m u m ro o ro � ro o o c m m o o 0 0 0 0 0 0 T - z a � m m a o 0 u V z z u m m u m m m u m m m ro u m m - - a '^ T z x x m x a m x r o z c m (D x o a a a - r s lo = a ti o a o 1 ° m m L o o o ' s o '� °c s a m °m ` o a ` 5 o 0 o u 3 0 Y o o o u o °a Y s o `�' s o u x o u °° 3a > o s uo o �a o '� o as Y o a o o,�a moa o >, 3 LL x x 3 m o - b lo o ow °� CITY OF SOUTHLAKE CRITICAL DRAINAGE STRUCTURE REPLACEMENT PROGRAM TIER II U- TIER III • OTHER REVIEWED LOCATIONS ♦ M --.. ♦ m 1 G I -4 INDIAN CREEK KI LAKE GRAPEVINE v v�t 9M, N 17 Cn Q -3 CITY OF SOUTHLAKE 9 RL NEEL— SCHAFFER + Cheatham & Associates 1 BIG BEAR CREEK k t; r �����p lozz 13, 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 aa� air 1 tAEEK - SOIUTHLAKE _ II -6 ' -- efinnc.r 11 -7 III.. REEL- XRPFFER PRIORITIES _ S + cn-h—si AsaoW. TIM R 1 eaabci • TIER 111 • SOyF. _ oni • II -8 L OC ATI ON S L • • e cheek �`i a •,� �,.. _ �w �� a -,.� • ,E , - - - - -- �o ry � 9 B Bfn:K9 II -4 I 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.