May 22, 2012 ASFPM - San Antonio Mike Moya, PE – Halff Associates Brian Reis, PE – RPS Espey Brian Wells, PE – MWM Design Group Purpose is to determine what Texas communities are doing above the minimum FEMA standards Developed by members of TFMA & ASCE/EWRI On-line survey from Aug ‘11 to Feb ‘12 Workshop was held Sept. ‘11 at TFMA’s fall conference Activities that could adversely impact another property or community will be allowed only to the extent that the impacts are mitigated or have been accounted for within an adopted community-based plan 3 Principle developed NAI Toolkit Legal Aspects of NAI Coastal NAI funded by NOAA www.floods.org/ 4 Physical increases ◦ ◦ ◦ ◦ ◦ Peak flow rates Frequency of bank full conditions Stormwater pollution Sediment transport (aggradation) Etc. Physical reductions ◦ ◦ ◦ ◦ Base flow Infiltration Sediment transport (degradation) Etc. The NFIP Regulations mandate that participating communities adopt and enforce at least the minimum standards of 44 CFR 60.3 Reference: 44 CFR 59.2(c) Communities may exceed the minimum standards and are encouraged to do so Reference: 44 CFR 60.1(d) When the NFIP was established in 1968, it was decided that minimum development standards would be required for participation They were considered sufficient to establish a balance between an acceptable level of flood risk versus difficulty in conducting the local program Goal: Keep the program as simple as possible so more communities will enroll Even with the minimum FEMA standards, flood damages in the United States have continued to increase “No Adverse Impact floodplain management is where the action of one property owner does not adversely impact the rights of other property owners, as measured by increased flood peaks, flood stage, flood velocity, and erosion and sedimentation.” Located between Austin and San Antonio Population 45,000 Home of Texas State University San Marcos River ◦ Popular recreation area ◦ Home to several threatened or endangered species Texas Blind Salamander Fountain Darter Texas Wild Rice Will be subject to EPA MS 4 regulations Amarillo FW D El Paso Austin SA Laredo Brownsville Houston 25-year and 100-year are to be conveyed / contained within ROW or drainage easements Peak flow shall not cause increased inundation of any building or roadway for the 2-, 5, 10-, 25-, 50- or 100-year storm frequencies. Fully developed conditions upstream. Detention is required for the 2- and 25-year frequency storm events. Development within the floodplain shall not increase the base flood elevation by more than 1 foot. Development within the floodway shall not result in any increase in the base flood. Floodplain alterations shall not create an erosive water velocity (> 6 fps) on- or offsite. San Marcos Limits on impervious cover ◦ Slopes (i.e. <15%, 15% to 25%, > 25%) ◦ Special areas: Edwards Aquifer, SM River Corridor ◦ Additional restrictions: water quality and buffer zones Permanent BMPs ◦ Edwards Aquifer - limits increase in TSS to 20% ◦ SM River Corridor - capture first ½ inch San Marcos Comprehensive Planning In progress Land use suitability analysis Identification of environmental metrics Develop new sustainability standards: detention, drainage, erosion, sedimentation control, archeological site protection, etc. ◦ Consideration of Habitat Conservation Plan Goals ◦ ◦ ◦ ◦ Habitat Conservation Plan, December 2011 ◦ ◦ ◦ ◦ ◦ Result of the EA Recovery Implementation Program Identifies species and habitat Identifies biological goals Includes ‘take’ coverage Activities required to minimize impacts USFWS to issue Incidental Take Permit based on HCP Permittees ◦ ◦ ◦ ◦ ◦ San Marcos New Braunfels Texas State University Edwards Aquifer Authority San Antonio Water System (SAWS) A collaborative, consensus-based stakeholder process. Plan to protect the federally-listed species affected by the management of the Edwards Aquifer and other activities. The goals of the HCP include contributing to the recovery of these species. Restoration of Texas Wild-Rice Expanded program of monitoring water quality Management of recreational use Management of aquatic vegetation and litter Control non-native and predator animal species A program to register, permit and evaluate septic systems Reduce impacts of IC through BMPs/LID Etc. The Corridor Development Certificate Process (CDC) affirms local government authority for local floodplain management and establishes a set of Common Regional Criteria and procedures with the goal of minimizing flood risks along the Trinity River Corridor in north central Texas The Corps Regional Environmental Impact Statement Trinity River and Tributaries – 1988 (TREIS) determined that the cumulative impact of allowing individual development projects in the Trinity River floodplain could be both measurable and significant. Corps of Engineers Record of Decision (1988) No rise in the 100-year or SPF elevation for the proposed condition will be allowed. The maximum allowable loss in storage capacity for the 100-year (0%) and SPF (5%) Alterations in the floodplain may not create or increase an erosive water velocity on or off-site.” Trinity River Steering Committee, facilitated by the NCTCOG. Statement of Principles for Common Permit Criteria (January 1988) Resolution for a Joint Trinity River Corridor Development Certificate Process (December 1988) Regional Policy Position on the Trinity River Corridor (January 1989). First edition May 1991 Common Regional Criteria No increase in the 100-year flood water surface elevation (within 0.04 feet) and no significant increase in the Standard Project Flood water surface elevation A maximum allowable decrease of valley storage in the 100-year flood and Standard Project Flood discharges of 0.0% and 5.0%, respectively No creation, or significant increase, in erosive water velocity on-site or off-site Benefits Common Regional Criteria Hydrologic modeling based on year 2050 Upper Trinity River watershed development Hydraulic model incorporating CDC permitted floodplain development U.S. Army Corps of Engineers technical review Regional review and comment Guarantee of local control of floodplain development decisions Questions 1. 2. 3. 4. 5. 6. What standards apply to quantify adverse impacts? What is considered to be an insignificant impact? What mitigation measures are required? Which storm events are regulated? What physical / chemical properties are regulated? What specific challenges have you encountered? 50 participants Communities varied in size NFIP Standards 68.0% Peak Flows 60.0% Floodplain Elevations 72.0% Other 25% Yes Yes Velocity and TSS 18.0% 0% Yes 50% 75% 100% 50 respondents No Policy No increase allowed in Zone AE No rise in floodway Peak: 0 cfs – 10 cfs or 0% - 2% Elevation: 0 ft. – 1.0 ft 1 foot rise no rise 0 cfs 0.00 feet 87.5% On-Site Detention On-Site Retention 16.7% DS Channel Improvements 50.0% Valley Storage 39.6% Regional Detention 58.3% Fee in Lieu 20.8% Other 16.7% 0% 25% n/a 50% 75% 100% 48 respondents 2-year 100.0% n/a 36.0% 5-year 12.0% 10-year 46.0% 25-year 40.0% 50-year 18.0% 100-year 250-year 0.0% 500-year 4.0% PMF 8.0% Other 2.0% 0% 25% 50% 75% 100% 50 respondents Water Quality 46.2% Stream Erosion TSS velocity 64.1% Base Flow HCP 12.8% Infiltration / GW recharge 10.3% Sediment Transport 30.8% Wetlands/Riparian Zones 43.8% Other n/a 7.7% 0% 25% 50% 75% 100% 39 respondents Educating developers, engineers, and politicians Retention / Detention standards Using preliminary data to regulate New FEMA flood maps Conflicting regulations of adjacent communities/districts Defining “significant” impacts to upstream and downstream properties Lack of enforcement Consistency in Engineering methodologies Regulating multiple storm frequency events Diane Calhoun Rob Connell W. H. Espey Nefi Garza Steve Gonzales Steve Graham John Hewitt Romin Khavari Melinda Luna Sharon Mattox Sam Riley Medlock Mike Moya Michael Newman Brian Reis Roy Sedwick Brian Wells TFMA FEMA Region VI AAWRE, President-Elect City of San Antonio ASCE - San Antonio San Antonio River Authority TFMA Assistant Workshop Coordinator City of Grand Prairie TX Section EWRI, Chair Vinson & Elkins, LLP ASPFM TFMA Workshop Coordinator (Halff Assoc.) City of Temple TFMA Workshop Coordinator (RPS Espey) TFMA TFMA Assistant Workshop Coordinator EQ Recharge Zone San Marcos