6/9/2014. An overview of the upcoming 25th anniversary of the highly visible, multijurisdictional, Outline of Presentation

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1 A 25-Year History The Impact of the Trinity River Corridor Development Certificate (CDC) Program Texas Floodplain Managers Association, Spring Conference, May 30, 2014, Irving, TX Presented By: Edith Marvin, PE, CFM NCTCOG Jack Tidwell, AICP, CFM NCTCOG Jerry Cotter, PE Corps of Engineers, Fort Worth District T. Lynn Lovell, PE, CFM, D.WRE Halff Associates, Inc. Outline of Presentation Introduction, Objectives and History Regional (NCTCOG), Federal (USACE), and Private Perspectives. Conclusions Introduction An overview of the upcoming 25th anniversary of the highly visible, multijurisdictional, North Texas regional floodplain management program and the Corridor Development Certificate (CDC). The CDC is a component of the COMMON VISION for the Trinity River 1

2 Why is this important? The COMMMON VISION program developed in the late 1980 s. Cooperative management effort among local governments along the Trinity Corridor, NCTCOG, and the USACE Results in a comprehensive and regional approach in Addresses flood damage reduction, recreation, and environmental quality Map of CDC Jurisdiction COMMON VISION - CDC Manual Founding Communities and Agencies Arlington Carrollton Coppell Dallas Farmers Branch Fort Worth Grand Prairie Irving Lewisville Dallas County Denton County Tarrant County Tarrant County Water Control and Improvement District Number One Trinity River Authority of Texas United States Army Corps of Engineers, Fort Worth District Federal Emergency Management Agency North Central Texas Council of Governments 2

3 Goals of the Trinity River COMMON VISION A SAFE Trinity A CLEAN Trinity An ENJOYABLE Trinity A NATURAL Trinity A DIVERSE Trinity Common Permit Criteria Permit criteria for all floodplain projects (not just for USACE permits). Each city still retains development permit authority. Consistent design level of protection Adopted by every member Any public or private development must obtain a CDC (unless specifically exempted) History Early 1930 s Dallas Floodway levee system constructed; rebuilt in late 1950 s 1972 Clean Water Act involving USACE permits Land development boom of the late 1970 s and early 1980 s cumulative impact within the Trinity River floodplains due to reclaiming lands through levees, fill, and channelization, often affecting wetlands and other environmentally sensitive areas. Identified a need for a unified, regional approach to floodplain development and permitting. 3

4 History December, 1984: USACE began a Regional Environmental Impact Statement (REIS) REIS, Completed in October 1987 the cumulative impact of development is Measurable and Significant April 1988, Record of Decision issued by Corp s District Engineer History Record of Decision (1988) The Corps of Engineers Record of Decision related to Section 404 permits along the Trinity Corridor and was signed by the district engineer and became the initial technical basis for the CDC criteria manual. History Record of Decision (1988) It noted inconsistent development permitting Upstream and downstream impacts Cumbersome multi-governmental permitting Cooperative review/comment system needed Decision makers need consistent information Local Governments were recognized as the ultimate floodplain managers for the river 4

5 Technical Criteria From Record of Decision/CDC Manual 1. No rise in the 100-year flood or significant rise in the SPF 2. Maximum allowable loss in valley storage capacity for 100-year flood and SPF discharges will be 0% and 5% respectively 3. No erosive velocities (on or off site) Technical Criteria From Record of Decision/CDC Manual (cont.) 4. Equal conveyance reduction on both sides of the channel (comply w/fema) 5. Hydraulic Impacts Tributary Projects (Same as river, within Regulatory Zone) 6. Mitigate Cumulative Impacts (Upstream/Downstream/Adjacent) History In light of the new ROD, in 1988 Member cities came forward to form the NCTCOG Trinity River COMMON VISION Steering Committee 5

6 History 1989 Regional Policy Position on the Trinity River Corridor (some elements): The Trinity River Corridor is a unique regional resource in the heart of the DFW Metroplex. Individual local goals can only be achieved through cooperative management. Stabilize the existing risk of flooding. Use of open space along the Trinity for parks and trails. History March 1990, Corps Reconnaissance Report Upper Trinity River Basin was published. Interlocal Agreements signed by member cities & Congress authorizes the Upper Trinity River Feasibility Study (UTRFS) August 1990, a multi-year/multi-million dollar Upper Trinity River Feasibility Study authorized through a cost sharing agreement between the US Army Corps and the NCTCOG. This agreement is still in effect. History (continued) Upper Trinity River Feasibility Study (UTRFS) - initiated in 1990 with study purposes including: Flood Damage Reduction (Regulatory models adopted initially in 1995 and updated in Submitted in late 90s as NFIP restudy) Water Quality Environmental Restoration Recreation Other Allied Purposes Project Management Plans were a product of the study Big Fossil Watershed Study, Clear Fork/West Fork, and Dallas Floodway & Elm Fork these included components from each of the goals 6

7 History Large flood events in 1989, 1990, and 1991 Ray Roberts & Joe Pool Lake Project Completion Helped to Prevent Greater Damages SH360 northbound after 1989 floods Rochester Park Dallas 1990 flood History Corridor Development Certificate The CDC process and criteria manual was adopted on May 23, 1991, by communities along the Trinity River and major tributaries, and became a key ingredient in the COMMON VISION for the river corridor. 7

8 History CDC Manual Edition 1 published on May 23, 1991 Edition 2 published in September 1998 Edition 3 published in 2003 Edition 4 published in July 2009 History - CDC By 2013, over 100 floodplain development/reclamation projects had been permitted through the CDC program, significantly reducing the cumulative flooding effects of the projects. CDC Regulatory Zone Sample above shows use of the Upper Trinity River Reconnaissance Report s 100-year and SPF for first Regulatory and Review Zones of CDC. These were used as zones in first 3 editions of Manual Now, single regulatory zone is determined by CDC administrator using the FEMA 100 delineation along the Corridor as guide. 8

9 CDC Permit Process Recent History Nearing completion of the UTRFS (study initiated in 1990) Most recent hydrology and hydraulics regulatory model adopted by Steering Committee and effective January 1, 2014 Wrapped up Project Management Plans Big Fossil Watershed Study (2010) Dallas Floodway & Elm Fork (Dallas ongoing project) Working on an update to the 4 th edition CDC Manual to include updated model and improved process Recent History (cont.) Improved online resources and website information Continued promotion of the benefits of the Community Rating System program Continuing investigation of new management strategies throughout the Upper Trinity Basin: addition of other river areas and partners methods to reduce runoff, watershed-wide, due to urbanization Incorporation of corresponding improvements to Water Quality, Environmental Restoration, and Recreation 9

10 Regional Perspective NCTCOG Limits (but does not eliminate) the impact of floodplain encroachments for regulated streams on downstream areas Establishes a consistent regional criteria Provides a funding stream for needed updates and new tools Provides oversight for projects constructed in the 100 yr floodplain Allows development in the floodplain Regional Perspective NCTCOG Applies to all encroachment projects, not just those requiring 404 permits Allows all FMTF members to review projects for the entire Trinity corridor footprint Provides a consistent review process Regional Perspective NCTCOG 10

11 Corps of Engineers Perspective 2013 CDC UPDATE Why Update? Land use changes and higher growth rates than initially projected In some areas, 2005 actual growth exceeded original 2040 projections Development took place in different areas than projected Urbanization impacts are significant (3.9 million to 6.4 million) Impacted peak runoff rates for regulatory discharges 11

12 Population in Millions mil mil Current 6.4 mil Population Growth and Watershed Development 14.0 Population Year (million) proj Urbanization of Dallas-Fort Worth Scope of the Study Mary s Creek (SUB30) yr = 27,400 cfs SPF = 68,200 cfs 100-yr = 37,300 cfs SPF = 88,800 cfs 12

13 Cost of Development Why Update? Incorporate constructed and permitted projects (91) into the models Evaluate impact of projects Determine effectiveness of CDC program Updated storage functions throughout river system Brought regulatory horizon from 2040 to 2055 Brought existing conditions from 1992 to 2005 Sets the stage for a future FEMA update Watershed Overview Comparison of Hydrologic Methods $ $$$ Regression Equations Statistical Hydrology Numerical Modeling Low Quality of Results High 13

14 Statistical Hydrology Never adopted Regulation Urbanization (non-homogeneous) Climate variability Never adopted Tropical Storm Hermine (7-9 Sept. 2010) Extremely dry conditions leading up to storm 24 hr 100-yr point rainfall, 25-yr basin average only produced 10-yr runoff Observed flow = 44,200 cfs Adjusted flow = 66,000 cfs Ray Roberts 8.99 Ray Roberts Ray 8.99 Ray Roberts Roberts Ray Roberts Lewisville Lewisville 9.17 Lewisville Cooper 9.17 Lavon Basin Cooper Lewisville 8.00 Lavon 4.53 Basin 9.17 Lewisville Cooper Grapevine Grapevine 9.17 Lavon Basin Cooper 8.00 Lavon 4.53 Basin Grapevine 7.31 Grapevine Cooper 7.31 Grapevine Lavon Basin Benbrook Joe Pool 4.34 Benbrook Joe Pool Bardwell Benbrook Joe Pool 7.83 Bardwell 4.34 Benbrook 8.94 Joe Pool Proctor Whitney Aquilla Proctor 5.51 Whitney Aquilla 8.94 Bardwell 7.83 Bardwell Benbrook 2.89 Navarro Proctor Waco 5.51 Whitney 7.07 Aquilla Mills Navarro Proctor 5.41 Waco 5.51 Whitney 4.34 Joe Pool 7.07 Aquilla Bardwell Mills Navarro 2.89 Belton 5.41 Waco Mills Navarro Proctor 5.54 Belton 5.41 Waco Whitney 6.20 Mills Belton Aquilla 6.20 Navarro 5.54 Belton Waco 7.07 Mills 5.54 Stillhouse Stillhouse Belton Stillhouse 5.42 Stillhouse 5.42 Wright Patman Wright 2.89 Patman Wright 2.89 Patman Wright 2.89 Patman 2.89 Wright Patman 2.89 Lake O the Pines 0.50 Lake O the Pines 0.50 Numerical Modeling Dallas Fort Worth USACE USGS Urban Hydrology Studies Millions invested 1950 s 1970 s USACE leveraged Urban Studies to develop regional methods 14

15 Depth of Rainfall in Inches Verification Storm Reproductions 40.0 Standard Project Flood (SPF) Extreme Events - Above SPF 24 Hour Rainfall for 10 Sq. Mi HMR 51/52 PMP HMR 51/52 SPS , 18.1 SPF Type Events Depth of Rainfall for 10 Sq. Mi. 50-Year 100-Year SPS PMP Year Rainfall Year Rainfall Tropical Storm Norma (1981 Clyde Storm) 15

16 Transposed Tropical Storm Norma (Transposed 1981 Clyde Storm) Design Storms Advantages Better represents actual rainfall events Provides realistic runoff projections to outlying areas such as the Village Creek upper watershed Can be modeled with existing USACE tool and enhancements are planned to further simplify Disadvantages Complex Depth area relationship is not consistent with NWS TP40 Figure 15 for areas less than 400 mi yr Design Storm (Walker Branch Centering) 16

17 Storage Volume (acre-ft) Storage Volume (acre-ft) CDC Update Study Scope Hydrology 110 sub-basins 30 routing reaches Land use updates 2005 base conditions 2055 future conditions Valley storage updates from river hydraulics permitted projects Conversion and comparison of HEC-1 to HMS Design storms CDC Update Study Scope River Hydraulics Incorporation of 91 constructed and permitted projects into river hydraulic models Impacts of constructed developments on WS elevations and storages Conversion to most up-to-date modeling technology (HEC-RAS) Merge of HEC-2 and HEC-RAS storage and conveyance models Approximately 600 new cross-sections New topographic for 1/3 of study area New assumptions Storage Accountability Preferred Storage 2012 Storage yr Discharge (cfs) Inherent redistribution of storage Typical Discharge (cfs) 1995 Storage 2012 Storage yr 17

18 Geographic Location Discharge Comparison Elevation Comparison 4th Edition Update 4th Edition 2013 Update Diff. "Future "Future" (cfs) (%) "Future" "Future" (ft) Clear Fork University Drive 39,800 50,100 10,300 26% West Fork State Highway , ,400 13,500 14% Elm Fork SH ,100 45,400 2,300 5% Trinity River Main Stem Commerce Street 119, ,600 8,800 7% Geographic Location 100-Year SPF Discharge Comparison Elevation Comparison 4th Edition Update 4th Edition 2013 Update Diff. "Future "Future" (cfs) (%) "Future" "Future" (ft) Clear Fork University Drive 84,000 94,700 10,700 13% West Fork State Highway , ,000 12,400 6% Elm Fork SH ,200 94,000-12,200-11% Trinity River Main Stem Commerce Street 277, ,700 17,700 6% The CDC program has been effective Findings Uncontrolled development (loss of valley storage) would result in increased discharges and water surface elevations Population growth and watershed development have occurred more rapidly and in different areas than originally predicted Findings The CDC program does not limit the significant impact of loss of valley storage, as well as increased urbanization and impervious cover, in non-regulated portions of the watershed Discharges and water surface elevations have increased as a result of development in upstream areas not regulated by the CDC program Discharges increased up to 30% Water surface elevations increased up to 3 feet 18

19 Future Considerations Consistent regional storm water management goals, policies and practices could complement CDC valley storage preservation program and be an important strategy to manage increased peak discharge rates due to urbanization New hydrologic techniques may be required as storm water management practices are adopted Trinity River Corridor Development Certificate (CDC) Floodplain Permitting A Private Perspective Case Studies 19

20 Effects of REIS/CDC Process on Land Development Case Study 1: 1. A 530-ac reclamation project proposed prior to the REIS/CDC would have removed 60% of the valley storage, reclaimed 285 ac. 2. Project, at the same location, was later designed to develop less than one third of the original project lands. 3. Remainder dedicated to mitigation Site Plan - Pre-CDC Criteria 100% Loss of Valley Storage! Reclaim Almost 500 acres Early - CDC Criteria Site Plan Reclaim 285 acres 20

21 Post-CDC Criteria Implementation Site Plan Reclaim 200 acres Post-CDC Criteria Development Reclaim 200 acres Specific Effects of REIS/CDC Process on Land Development Development Condition Pre-CDC CDC Reclaimed Acres /- acres acres 21

22 Case Study 2: Effect of REIS/CDC on Land Development 1. Large reclamation project proposed prior to the REIS/CDC would have removed 38% valley storage and reclaim 315 acres! 2. Project, at the same location, was later (post CDC) designed to reclaim only 150 acres 3. Remainder dedicated to mitigation. Pre-CDC Criteria Implementation Site Plan Reclaim 315 acres Post-CDC Criteria Implementation Site Plan Reclaim 150 acres 22

23 Specific Effects of REIS/CDC Process on Land Development Development Condition Pre-CDC CDC Reclaimed Acres acres acres* Conclusions: Private Perspective 1. Less developable acres 2. More open-space, wetland-wildlife mitigation areas dedicated/restricted 3. Increased cost per acre for reclamation projects 4. Extended time and costs in obtaining permits 5. More difficult to justify economically Final Conclusion: Private Perspective Thank You John Promise for Your Vision! CDC is for Me Let s Have Some Common Vision Around Here! 23

24 Closing Reflections: Does the use of the CDC Concept, as a floodplain management tool, encourage sustainable, resilient, and prudent floodplain-related decisions and policies, now and in the future? A 25-Year History The Impact of the Trinity River Corridor Development Certificate (CDC) Program Thank You! Texas Floodplain Managers Association, Spring Conference, May 30, 2014, Irving, TX Presented By: Edith Marvin, PE, CFM NCTCOG Jack Tidwell, AICP, CFM NCTCOG Jerry Cotter, PE Corps of Engineers, Fort Worth District T. Lynn Lovell, PE, CFM, D.WRE Halff Associates, Inc. Findings (too busy) 100-Year Comparisons 100-Year "Future" Flood CDC CDC 2012 Revised CDC Model Comparison Manual 4 th Manual 4 th CDC 2012 Geographic Location Edition Edition Update Diff vs vs 2040 Location (ft) (cfs) (%) 2055 (cfs) (%) Clear Fork Clear Fork University Drive Henderson Street Clear Fork above West Fork 39,800 36,600-3,200-8% 48,300 8,500 18% West Fork West Fork SH 183 West Fork above Clear Fork 35,400 35, % 35, % University West Fork below Clear Fork (at Fort Worth Gage) 58,700 56,500-2,200-4% 69,400 10,700 15% Drive West Fork at State Highway ,900 95,400 1,500 2% 107,400 13,500 13% SH West Fork above Elm Fork 92,800 95,800 3,000 3% 103,100 10,300 10% Belt Line Road Elm Fork Loop Elm Fork at Sandy Lake Road (at Carrollton gage) 51,500 43,600-7,900-15% 48,200-3,300-7% Elm Fork Elm Fork above West Fork 42,700 41,400-1,300-3% 44,700 2,000 4% IH 35E Trinity River Main Stem Trinity River below confluence with Elm Fork/West Fork 120, ,200 1,900 2% 129,400 9,100 7% Loop SH Trinity River at Dallas Gage (Commerce Street) 119, ,600 1,800 2% 128,600 8,800 7% Trinity River Main Stem Commerce Street ATSF Railroad

25 Findings SPF Comparisons SPF CDC CDC 2012 Revised CDC Model Comparison Manual 4 th Manual 4 th CDC 2012 Geographic Location Edition Edition Update Diff vs vs 2040 Location (ft) (cfs) (%) 2055 (cfs) (%) Clear Fork Clear Fork University Drive Clear Fork above West Fork 84,000 82,600-1,400-2% 93,000 9,000 10% Henderson Street West Fork West Fork West Fork above Clear Fork 57,700 58, % 63,300 5,600 9% SH West Fork below Clear Fork (at Fort Worth Gage) 124, ,700-1,700-1% 135,900 11,500 8% University Drive West Fork at State Highway , , % 217,000 12,400 6% SH West Fork above Elm Fork 222, , % 234,200 11,500 5% Belt Line Road Elm Fork Elm Fork at Sandy Lake Road (at Carrollton gage) 99,200 84,500-14,700-15% 88,000-11,200-13% Loop Elm Fork Elm Fork above West Fork 106,200 92,200-14,000-13% 94,100-12,100-13% Trinity River Main Stem IH 35E Loop Trinity River below confluence with Elm Fork/West Fork 278, ,400 4,900 2% 296,200 17,700 6% Trinity River at Dallas Gage (Commerce Street) 277, ,300 5,300 2% 294,700 17,700 6% SH Trinity River Main Stem Commerce Street ATSF Railroad