Basalt gets grip on flood risk | AspenTimes.com

Basalt gets grip on flood risk

Since the last major spring runoff in 1995, Basalt has undertaken various studies that vaguely warn that 100 families in two trailer parks face a “substantial” threat from floods.The latest assessment finally shows just how substantial.A town consultant estimated there is a 25 percent risk that a catastrophic flood will affect the Roaring Fork Mobile Home Park and the Pan and Fork Mobile Home Park within the next 10 years.Rick McLaughlin, a water engineer, came up with the estimate after being pressed by Councilman Glenn Rappaport to quantify the risk. McLaughlin stressed that it was just a guess – but one based on six years of studies.”All I can tell you is it’s pretty bad,” McLaughlin said. “Even if this was a stable river, these [trailer parks] would be in a hazard zone.”The disclosure is significant because skeptics have felt Basalt’s motivation to relocate the trailer parks was fueled as much by aesthetics as safety concerns.Both trailer parks are built on the banks of the Roaring Fork River, just downstream from its confluence with the Fryingpan River. Both are partially located within the flood plain.The $17 million solutionA study by McLaughlin Rincon, a water engineering firm, thoroughly examines a 2.6-mile stretch of the Roaring Fork through Basalt, from the upper bypass bridge to the lower bypass bridge. It identifies natural features and man-made additions that create flooding risks and proposes solutions.McLaughlin labeled that stretch of river “one of the most unstable in the state” and also one of the most hazardous.Historically, during floods the river was able to spill its banks and rather benignly cover a 1,000-foot-wide swath of the valley floor with shallow water, the study showed. Development has narrowed the channel where the river is allowed to flow. Rocks and sand rolling down the river pile up in ways that add to the flooding threat.”Because the historic, natural river corridor is much wider than the space the river is currently ‘allowed’ to occupy, residential and commercial areas are threatened by the 100-year flood,” the study concluded.The cost to ease the flood threat, improve fish habitat and enhance recreation opportunities is $17 million. That doesn’t include relocating residents of the mobile home parks.”I’d say you’re a small town with really big problems,” McLaughlin said.The town is seeking federal grants to help with the funding, but it would take years to acquire $17 million, McLaughlin and town officials conceded. So they are setting priorities among the projects.CDOT bridge adds to woesThe focus is the river channel at and around the upper bypass bridge, which was built by the Colorado Department of Transportation in 1987 when busy Highway 82 was diverted around Basalt. McLaughlin called the construction of that bridge and a levee where the river slams into the bank just upstream of the bridge “one of the most significant impacts on the river” in the Basalt area.The alignment of that bridge allows rock and sand to collect upstream. That could cause the failure of the levee, which he said isn’t compliant with standards set by the Federal Emergency Management Agency.”Continuous debris deposition upstream of the bridge during high flows could overtop an existing berm and cause flooding of the south side of the town,” McLaughlin Rincon’s study said.”You weren’t problem free before the bridge, not by a long shot,” said McLaughlin. But the bridge took a bad situation and made it worse, he said.He advised rebuilding the levee, constructing walls to direct the flow better through the “poorly aligned” bridge, recontouring the stream bottom and adding diversions to handle high water. Those projects would cost about $5 million.CDOT had repeatedly denied that its bridge has contributed to Basalt’s potential flooding woes. Town officials said they will present this study to the agency to try to convince state officials to contribute to the solutions.Trailer park solutions eyedThe relocation of the mobile home parks also remains a significant hurdle. The developers of the Roaring Fork Club have proposed an affordable housing site as part of their expansion plan. The developers have suggested dedicating some of that housing to relocate Pan and Fork residents. However, it still hasn’t been determined who will pay for that housing.The owners of the Roaring Fork Mobile Home Park are also working on a redevelopment plan that includes building replacement housing near Basalt High School.Even though the flooding threat to the trailer parks has been discussed for years, some Basalt officials concluded after hearing McLaughlin’s latest report that they must redouble efforts to inform residents of the trailers about the risk.”We owe it to people to let them know what we’ve found,” said Councilwoman Tiffany Ernemann.Scott Condon’s e-mail address is scondon@aspentimes.com


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