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HomeMy WebLinkAboutTBSS 02-27-17 Town of Estes Park, Larimer County, Colorado February 27, 2017 Minutes of a Study Session meeting of the TOWN BOARD of the Town of Estes Park, Larimer County, Colorado. Meeting held at Town Hall in the Board Room in said Town of Estes Park on the 27th day of February, 2017. Board: Mayor Jirsa, Mayor Pro Tem Koenig, Trustees Holcomb, Martchink, Nelson, Norris and Walker Attending: All Also Attending: Town Administrator Lancaster, Director Hunt, Planner Kurtz and Town Clerk Williamson Absent: None Mayor Jirsa called the meeting to order at 2:00 p.m. OVERVIEW OF STATE-WIDE HAZARD MAPPING EFFORTS AND ESTES PARK CONTEXT. Kevin Houck/ Chief Watershed and Flood Protection Division, Colorado Water Conservation Board provided a review of Senate Bill 15-245 passed by the General Assembly to provide new flood maps, hydraulic analysis, and mapping erosion zones. The funding became available on July 2015 and expires on July 30, 2018. He stated the hydrology needs to be updated as it is over 40 years old, and additional stream gauge information has been recorded providing hydrologist with a better understanding of rainfall. Preliminary analyses suggested the flood risk has been under portrayed in many areas, and recovery should proceed based on current updated data. The areas reviewed during the study includes South Platte River, Big Thompson River, Little Thompson River, St. Vrain Creek, Left Hand Creek, Boulder Creek and Coal Creek, and numerous tributaries to above watersheds. The mapping process would include updating hydrology, gather updated terrain data, survey river infrastructure as needed, prepare hydraulic model to determine flood elevations, and overlay flood elevations on to terrain map to produce floodplain boundaries. The next steps would be the adoption by the State, finalization of the hydraulic analyses using updated hydrology and topography, prepare draft floodplain maps in 2017, finalize floodplain maps in 2018, data provided to FEMA to incorporate into Flood Insurance Study and Flood Insurance Rate maps, and begin mitigation study to develop and analyze alternatives. The 2013 flood was included in the study because it happened, no physical or statistical reason it can’t happen again, the flood did not meet any meteorological or statistical criteria to be considered an outlier, and the flood was a data-rich event that allows for a high level of calibration not normally available. STUDY RESULTS AND OVERVIEW OF SCIENCE BEHIND THE STUDY. Dr. Andrews Earles/Wright Water Engineers, Inc. Lead Engineer provided a review of the hydrology study process and results. The study was completed with the public health, safety and welfare of the Estes Park citizens as the priority. The study utilized gauge information from the 1970s and new precipitation data developed by NOAA, which includes 40 years of data. Mayor Pro Tem Koenig questioned how flood insurance premiums are established. He stated the flood insurance map may change based on the hydrology study; however, homeowners maintaining or purchasing flood insurance now would be locked into the current rates established by the floodplain maps adopted by FEMA, and would not change unless the property owner has a lapse in coverage. Rates would likely increase for those acquiring new flood insurance after the new floodplain maps are develop and adopted. Town Board Study Session – February 27, 2017 – Page 2 The rather large watershed surrounding Estes Park comprised of 40 square miles for the Fall River watershed and over 80 square miles for the Big Thompson contain rock outcrops and impermeable soil which can produce significant flows during an event. He stated scientifically accepted methods and sound engineering principles were used to produce a reasonable 100-year flow rate. The study should tie back to reality by comparing it with actual rainfall/runoff events. A preponderance of evidence was used to complete the study, which included rain gauges, stream gauge data, high watermark, additional data points collected by Dr. Robert Jarrett, and modeling completed with the data that proved to be close to the highwater marks. Mayor Jirsa stated concern with the data included in the study and questioned the process utilized to collect the data after the event. Dr. Earles reviewed the hydrology study process which included a public meeting in April 2016, a draft report in July 2016, additional peak flow estimates from the 2013 flood, additional analysis and recalibration of the study, 16 individuals provided peer review of the study, revised report submitted to FEMA in December 2016, approved by FEMA in January 2017, and a final report issued January 25, 2017. A review of Bulletin 17B was provided which provides a method to address high outliers. It was the opinion of Dr. Earles, the 2013 flood was not a statistical outlier and the data was included in the study because the rate of rainfall was not substantial compared to other rainfall events on record. The ground was already saturated which impacted the rate of water flow above ground. The peak rainfall was an ordinary event. Trustee Walker commented the significant issues that occurred during the flood event such as large landslides would suggest the event was an outliner. The study results proposed new Flood Insurance Study peak discharge and recommended flows much higher than the existing rates in both the Fall River and Big Thompson River; however, the numbers are lower than those established by CDOT earlier. Dry Gulch peak discharge would decrease significantly as no credible data could be established for the high rates in the previous published numbers. Mayor Jirsa questioned the confidence level for the report. Dr. Earles stated the report has a plus or minus 20% statistical accuracy, which is consistent with most hydrology studies. Mayor Jirsa stated concern with the development of floodplain maps based on a 20% difference and the impact it could have on development and redevelopment downtown. RESPONSIBILITIES OF FEDERAL, STATE AND LOCAL GOVERNMENT AGENCIES THROUGHOUT THE STUDY AND REMAPPING PROCESS. David Sutley/FEMA stated a grant would be submitted by the State of Colorado to develop new floodplain maps which would be developed through 2018. FEMA completed a full review of the data used in the hydrology study because the final hydrology study would be used in applying for the grant and preparing the proposed floodplain maps. The draft maps would be presented to the public for review and public meetings would be held. FEMA would consider appeals to both the map and the hydrology study. The Town can begin to address mitigation measures prior to the final adoption of the new floodplain maps to make the town more resilient. The local ordinance to adopt the new maps would occur at the time the new maps are officially adopted by FEMA. Kevin Houck/ Chief Watershed and Flood Protection Division, Colorado Water Conservation Board stated the State role would be to assist the local community with regulations and floodplain mapping. The State would develop the floodplain maps for review by FEMA. He stated the Town Board would need to decide on whether or not to adopt the hydrology study numbers now or wait to adopt the new numbers once the maps have been finalized and adopted by FEMA. Adopting the new numbers now would reduce property owner flood insurance rates moving forward and reduce the risk of future flood by implementing mitigation methods for new and redeveloped properties. Town Board Study Session – February 27, 2017 – Page 3 Tina Kurtz/Planner stated the Town manages its own floodplain and belongs to the National Flood Insurance program which allows property owners to apply for flood insurance. Floodplain regulation and enforcement protects properties from the impact upstream and downstream. The Town has adopted a temporary Ordinance that directs staff to utilize the best available data. The Ordinance expires in May 2017; therefore, the Board would need to provide staff with direction prior to the expiration on how to move forward. QUESTIONS & PUBLIC COMMENT Todd Plummer/Van Horn Engineer questioned if the study has been adopted by the study. Mr. Sutley/FEMA stated the hydrology study would not be officially adopted until the regulatory maps have been adopted. Mr. Plummer stated concern with the Fall River flow measurements and estimates, and would argue the 2013 flood should be considered a high outlier and should not be included in the study. The inclusion of the numbers would have a significant impact on the final flow rate for Fall River. He suggested the flows be considered historic for the Fall River and the rate of discharge be set at a more realistic 1,000 csf. Bill Van Horn/Van Horn Engineering commented the 100-year flood rates should be used to establish the new peak discharge and flows. He stated there was a wealth of data that should have been used in the study that was not utilized. He requested the Board refer the study back to the consultant to review additional data and to provide flows that would meet the 100-year flood numbers. John Spooner/Van Horn Engineering stated the study should have reviewed adjoining watersheds in the analysis. The study should have also reviewed Bulletin 17B procedures. Brian Varrella/CDOT Region 4 Hydraulic Engineer stated during his peer review he reviewed both the data and the process used to complete the hydrology study and concurred with both. There being no further business, Mayor Jirsa adjourned the meeting at 4:14 p.m. Jackie Williamson, Town Clerk