RANGELY | During the Oct. 15 Board of County Commissioners work session, county planner/surveyor Leif Joy and engineer and Rangely town planner Jocelyn Mullen brought concerns to the commissioners about a recent study commissioned by FEMA and conducted by sub-consultant AECOM of Denver. Joy explained the process that was used for the study was LIDAR (Light Detection and Radar) which is a surveying method that measures distance to a target by illuminating the target with laser light and measuring the reflected light with a sensor. Differences in laser return times and wavelengths can then be used to make digital 3-D representations of the target. In this case they used LIDAR to determine height and elevations. They use this model and flood it to determine the floodplain. At some point Joy said that AECOM thought that they needed additional information for Rangely and contacted the county. The county flew the area with their drone and used aerial photography to develop the digital terrain model (DTM) and then merged that information with AECOMs model. AECOM used a drainage study from an area south of Rangely and Joy says that “when they flooded the model it took out all of downtown Rangely and included it in their floodplain.”
The Town of Rangely, worried about the results of the AECOM model, hired Paul Currier with Water Resource Consultants LLC in Rifle, Colorado. Joy said in his opinion Currier is an excellent hydrological engineer and Currier found some holes in the study performed by AECOM. He had some relevant conflicting information. Commissioner Moyer asked what is our role is in this? Joy explained that the county funded a large portion of the LIDAR. “We have the largest interest in this so that we map the best available floodplain as it affects insurance rates, zoning, etc.” Right now, Rio Blanco County is utilizing the data from this flood model.
“Currier contested their methodology, found errors in the model they were using, walked them through it, and got USGS—whose model they were using—to agree there was an error in this arena,” Mullen said.
“They also overestimated their peak flood flow, using an area known as College Canyon Draw, which parallels Dragon Road (south flowing northwest into Rangely) and at the bottom of White Avenue it turns and is routed down the ditch that runs perpendicular to White Avenue, Stanolind Avenue, and under River Road and flows out to the White River. AECOM are estimating the peak flood flow based on other areas that are gauged but this area is not. There is no historical record or gauging station for this area. Even though AECOM recognized the flaws in their methodology all they offered to do was to bring down their peak flood flow from 590 cubic feet per second that would be generated by a storm event down to 360.”
Mullen said Currier argued for a number closer to 150 cubic feet per second and AECOM are still rejecting Currier’s information and suggestions. Because of the way that they model it, the berm they used is not a certified berm built to U.S. Army Corps of Engineers cross sectional requirements and the Town of Rangely has not been able to find any documentation on how the berm was constructed. Without this berm being certified the Federal Emergency Management Agency (FEMA) will not give the Town of Rangely credit for having the berm and they model it as if it breaches several different locations. When they do that, even using the reduced flow, it still shows much of the southwestern portion of Rangely being in the floodplain. They claim that Rangely is only within 1 foot of peak flow elevation, but that leaves an estimated 80-100 homeowners in Rangely having to buy flood insurance. Mullen says she reiterated Currier’s information during a comment period that ended Aug. 9 because FEMA conveniently hadn’t included all of it in their records. She says that she commented that she wanted the entire body of the Town of Rangely’s comments and objections in the official record and that they still officially object to the flow that they came up with. She since hasn’t heard anything and says it makes her really nervous.
“The silence has been deafening. FEMA has been keeping the Town of Rangely in the dark.”
The Town of Rangely has several options as the county moves toward finishing its Hazard Mitigation Plan. She said the Town of Rangely becomes eligible to apply for different types of FEMA grant funding for flood mitigation projects. They are unsure whether they want to have the berm analyzed to determine if it could be certifiable. They could build an upstream retention pond somewhere between the cliffs that creates the rock crawling park where they could retain the storm event that FEMA is modeling. Another option would be to deepen ditches and change the engineering of the culverts that go up White Avenue, River Road and Stanolind Avenue, which she says would not be an inexpensive fix. Finally, if the Town of Rangely is unable to change FEMA’s proposed floodplain they would look at a way to subsidize flood insurance for affected homeowners who will be forced to buy it, because that may be the least expensive alternative. Flood insurance estimates are between $300-$1,000 per year. When the floodplain plan becomes official property owners who are forced to buy flood insurance, if they refuse to buy or do not maintain the insurance and the property sells, the new owners will have full force pricing of flood insurance from that point on. She says that they are still waiting to see where FEMA lands with this and the town has not budgeted in 2020 for any of the costs that could arise with the outcome.
Joy reports that most of Rio Blanco County benefits from the new floodplain, but the Town of Rangely is quite the opposite. The Town of Meeker is happy with the proposed floodplain because it considerably narrows their flooding and removes many structures from the floodplain. He says that it is very important to have this conversation and get the county and the towns on the same page. Mullen asked that the county give them support in applying for flood mitigation funds if FEMA goes through with this floodplain. Moyer said it only makes sense that the county get involved and his opinion is to let FEMA know that they got most of the floodplain right but they did not get it right in Rangely and they need to justify where they came up with these numbers. Tentatively, a work session meeting is scheduled on Tuesday Nov. 19 with a FEMA, CWCB, and AECOM representative, they will discuss the matter from their perspective. Commissioner Moyer encourages the public to attend.
By ROXIE FROMANG | Special to the Herald Times
