By Ann Baker, Communications and Marketing
Water cascades down the spillway at Gross Reservoir a week after the floods tore through the area.
The first night it started flooding, the caretakers, who live and work at Gross Reservoir climbed the hill and stayed awake most of the night, watching Advent Creek swarm their houses and office.
They tried to sleep the second night, “but we were too busy watching that garage door — that was our gauge for the water level,” said caretaker Steve Bauman.
When one of the worst storms in Colorado history submerged the Front Range in mid-September, it tore through the northern part of Denver Water’s collection system, forcing two treatment plants offline, reservoirs to swell and access roads to crumble in half.
The storm bumped up water storage 6 percentage points, the largest September increase in our current supply system’s history, said Bob Peters, water resource engineer. And so much rain water slid into Ralston Reservoir after operators turned off the South Boulder Canal — the channel that sends water to the reservoir — that water tumbled over the dam’s emergency spillway for the first time in the reservoir’s 76-year history.
“I’ve never seen anything like it,” said Delbert Brooks, Ralston caretaker. “I’ve never seen this much rain that lasted this long and did this kind of damage.”
During the three days of the storm, six operations field employees worked in shifts around the clock, watching for problems around the ditches, canals and siphons that connect Gross Reservoir to Ralston Reservoir, as well as along the Clear Creek Canal from Ralston to Golden. The inflow and outflow gauges at Ralston failed, dirt covering Siphon 5 sloughed off, and entire hillsides piled into the concrete-lined canal.
Floyd Sanchez, Denver Water equipment operator with the South Boulder District, reburies Siphon 5 after a flood washed away the dirt on top.
In the weeks after the storm, Denver Water employees worked to rebuild access roads and install washed-out culvert pipes. There will be months left of repair — crews need to repair Ralston’s emergency spillway, the sediment piled in the South Boulder Canal needs to be removed, and giant boulders restrained like a hairnet in a massive chain link fence need to be relocated. Roads need to be regraded, and the gauge houses at Ralston likely need to be rebuilt.
But really, Denver Water fared well compared to other Front Range cities that were swept away or cut in two by the floods. Most communities are assessing damage and don’t know what help they need yet. The weekend after the flooding started, St. Vrain and Left Hand Water Conservancy District borrowed a 20-inch butterfly valve and three 36-inch-diameter pipes, offering to replenish our stock later.
And Denver Water staff has already coordinated with the Office of the State Engineer regarding dam safety concerns around the state. As water recedes and damage is assessed, Denver Water’s technical staff and crews may be asked to assist other entities with inspections, along with system startups and testing, said Bob Mahoney, director of Engineering.
In the meantime, Denver Water crews will focus on clearing our roads and accessing our facilities — unplanned projects for sure, but nothing to complain about.
“It’s what we’re here for,” shrugged Tony Stengel, assistant foreman of the South Boulder District. “We don’t have it bad at all. A lot of people are in much worse shape than we are.”
Water flowed into Ralston Reservoir so fast that it topped out over the dam’s emergency spillway, the first time in the reservoir’s 76-year history that the emergency spillway had to be used.
Tony Stengel, assistant foreman of the South Boulder District, talks with Rich Abbott, Gross caretaker, about rebuilding the road leading to Gross headquarters. Caretaker Steve Bauman sits on the driver’s side.
Ralston Reservoir’s outflow gauge house toppled over during the floods, taking the water-measuring device with it.