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Austin Water Facility Planning for Atlas 14 Flood Risks Title of Presentation Presentation Date January 14, 2021 Facility Engineering Division Name of Person, Assistant Director Austin Water Facility Planning for Atlas 14 Flood Risks January 14, 2021 Flood Risk and Atlas 14: Overview (http://www.review.ci.austin.tx.us/atlas14) The National Weather Service (NWS) has completed a historical rainfall study, called ATLAS 14. ATLAS 14 means the National Oceanic and Atmospheric Administration's Precipitation- Frequency Atlas 14 of the United States, Volume 11, Version 2.0. This study shows that Central Texas is more likely to experience larger storms than previously thought. This means that severe flooding is also more likely. The City’s code amendments would redefine the existing 100-year and 25-year floodplain boundaries to reflect our new understanding of flood risk identified by the Atlas 14 study. The proposed code amendments would change existing City regulations that govern development in the floodplain. Measure Current Updated 100-year rainfall (24-hour) Buildings in 100- year floodplain 10.2 inches Up to 13+ inches 4,000 7,200* Percent Increase 30% 80% Austin Water Facility Planning for Atlas 14 Flood Risks January 14, 2021 http://www.review.ci.austin.tx.us/atlas14 What the City is Doing ? Ordinance No. 20191114-064 100-year Floodplain: City is changing the development code in order to protect the public from flooding. (A) For areas amended to incorporate Atlas 14 data, the 100-year floodplain calculated under fully developed conditions as prescribed by the Drainage Criteria Manual as amended to incorporate Atlas 14 data; (B) For areas not yet amended to incorporate Atlas 14 data, the 500-year floodplain either as depicted on the FEMA Flood Insurance Rate Map as of January 6,2016, as subsequently revised, or is calculated under existing conditions as prescribed by the Drainage Criteria Manual using data predating Atlas 14 25-year Floodplain (A) For areas amended to incorporate Atlas 14 data, the 25-year floodplain calculated under fully developed conditions as prescribed by the Drainage Criteria Manual as amended to incorporate Atlas 14 data; (B) For areas not yet amended to incorporate Atlas 14 data, the 100-year floodplain either as depicted on the FEMA Flood Insurance Rate Map as of January 6,2016, as subsequently revised, or is calculated under existing conditions as prescribed by the Drainage Criteria Manual using data predating Atlas 14 Colorado River For the Colorado River, the 100-year floodplain as depicted on the FEMA Flood Insurance Rate Map dated January 6, 2016, as subsequently revised. Austin Water Facility Planning for Atlas 14 Flood Risks January 14, 2021 https://www.austintexas.gov/FloodPro/ 2019 INTERIM FLOOD PLAIN Interim Atlas 14 100-Year COA Fully Developed 100-Year COA Fully Developed 25-Year Austin Water Facility Planning for Atlas 14 Flood Risks January 14, 2021 https://www.austintexas.gov/FloodPro/ 2020 FLOOD PLAIN PER REVISED ORDINANCE COA Fully Developed 100-Year COA Fully Developed 25-Year Austin Water Facility Planning for Atlas 14 Flood Risks January 14, 2021 Shaw Lane Water Facility Austin Water Facility Planning for Atlas 14 Flood Risks January 14, 2021 Austin Water Wastewater Treatment Facilities 2 = Major WWTP (SAR & WC WWTP) 1 = Biosoilds Plant (Hornsby Bend BMP) 8= Package Plants 1= Wholesale Customer WWTP 1 Facility in Current 100-Yr Flood Plain • T-Farms Package Plant 3 Additional Facilities in new ATLAS 14 100-Yr Flood Plain • SAR WWTP • Walnut Creek WWTP • Wild Horse Package Plant ` LEGEND East Brushy Creek WWTP Expansion Regional WWTP Solids Treatment Plant Package Plant (PP) Package Plant Decommission 7 Austin Water Facility Planning for Atlas 14 Flood Risks January 14, 2021 Austin Water Lift Station Facilities 135 = Total Number of Lift Stations (Does not include influent WWTP LS) 11 Facilities in Current 100-Yr Flood Plain 9 Additional Facilities in new ATLAS 14 100-Yr Flood Plain 6 Facilities adjacent to Colorado River Flood Plain 8 Austin Water Facility Planning for Atlas 14 Flood Risks January 14, 2021 South Austin Regional (SAR) WWTP Austin Water Facility Planning for Atlas 14 Flood Risks January 14, 2021 South Austin Regional (SAR) WWTP Austin Water Facility Planning for Atlas 14 Flood Risks January 14, 2021 Fallwell Lane Austin Water Facility Planning for Atlas 14 Flood Risks January 14, 2021 Fallwell Lane Flood Wall & Sheet Pile Option Austin Water Facility Planning for Atlas 14 Flood Risks January 14, 2021 Fallwell Lane – Grant and Funding Opportunities Texas Water Development Board Flood Infrastructure Fund (FIF): Funding Agency: Texas Administered by: TWDB (Texas Water Development Board) General Land Office Community Block Development Grant Mitigation (CDBG-MIT) funds: Funding Agency: HUD (Housing and Urban Development ) Administered by: GLO (Texas General Land Office ) FEMA Flood Mitigation Assistance (FMA): Funding Agency: FEMA (Federal Emergency Management Agency) Administered by: TWDB (Texas Water Development Board) FEMA Pre-Disaster Mitigation (PDM) / Building Resilient Infrastructure & Comminutes (BRIC): Funding Agency: FEMA (Federal Emergency Management Agency) Administered by: TDEM (Texas Division of Emergency Management) Tax Increment Reinvestment Zone (TIRZ): Tax increment financing (TIF) is method local governments can use to pay for improvements that will draw private investment to an area. Tax increment financing isn’t a new tax; instead, it redirects some of the ad valorem tax from property in a geographic area designated as a Tax Increment Reinvestment Zone (TIRZ) to pay for improvements in the zone. Austin Water Facility Planning for Atlas 14 Flood Risks January 14, 2021 Walnut Creek WWTP Austin Water Facility Planning for Atlas 14 Flood Risks January 14, 2021 Flood Wall Option 15 Austin Water Facility Planning for Atlas 14 Flood Risks January 14, 2021 Wild Horse PP Wild Horse Package Plant Gilleland Creek Austin Water Facility Planning for Atlas 14 Flood Risks January 14, 2021 Wild Horse PP Wild Horse Package Plant Sheet Pile Option Austin Water Facility Planning for Atlas 14 Flood Risks January 14, 2021 Southland Oaks Lift Station Bear Creek Tributary Austin Water Facility Planning for Atlas 14 Flood Risks January 14, 2021 Southland Oaks Lift Station Austin Water Facility Planning for Atlas 14 Flood Risks January 14, 2021 Southland Oaks Lift Station Cut and Fill Balance Option Austin Water Facility Planning for Atlas 14 Flood Risks January 14, 2021 Springfield Lift Station Austin Water Facility Planning for Atlas 14 Flood Risks January 14, 2021 • Springfield Lift Station Abandonment Option by Gravity Sewer Austin Water Facility Planning for Atlas 14 Flood Risks January 14, 2021 Austin Water Flood Mitigation Strategies Each AW facility will need to be evaluated for its unique flood risk and best mitigation measures Sites to be evaluated for flood berms/levees, raised buildings and structures, or flood proofing buildings at plants and lift stations AW continues to convert dry-pit, canned lift stations to submersibles lift stations with electrical and controls located above ground and above the flood plain Current projects include: Northwest and South Lift Station Area Improvements programs are addressing the Southland Oaks and Springfield Lift Stations Parmer Lane Tunnel will eliminate risk at some of AW’s more vulnerable lift stations, Lake Creek and Rattan Lift Stations AW will work collaboratively with Watershed Protection Department on a site-by- site basis to address flood risk while keeping a focus on Affordability – one of the City’s six Strategic Outcomes