In two different cities along Colorado's Front Range, the realities of flash floods have changed how infrastructure is constructed to handle rushing water.
In Sept. 2013, the City of Boulder reported over 18 inches of rain in the area, which caused 25- to 100-year flooding. A 100-year flood is an instance with a 1% likelihood of occurring any given year.
“I had seen natural disaster events before in my life on the news. But being here, being part of the city organization, and just seeing the devastation it had in the community and around the region was something that I never hoped to experience again," said Joe Taddeucci, director of utilities for the City of Boulder.
Taddeucci said Boulder has the highest risk for flash flooding when compared to any other Colorado city because of how close it is to the mountains.
“It's an older city. It was developed in the late 1800s,which was before modern floodplain regulation," Taddeucci said about Boulder. "So a lot of development had already happened. And like a lot of older cities, we're playing catch-up to implement our flood projects.”
One of the projects, which was done prior to 2013, added more area under the Broadway Bridge where it passes the Boulder Creek to ensure there is more capacity for water to flow under the bridge before causing traffic impacts. Other projects were completed after the 2013 flood.
“There are a lot of drop structures on the creek, which is where there's large rocks placed all across, so that the water kind of falls in a step fashion to control the the velocity of the flow and erosion potential," Taddeucci explained. "The 2013 flood was so extreme that it moved those big rocks that were the size of cars and things, and so there were dropped structures replaced all the way from here up to the mouth of the canyon."
On Wednesday night, the Boulder area experienced anywhere from two to three inches of rain. The ground is now saturated with water, and if more rain drops, the new water would not have anywhere to go since it cannot be absorbed by the soil. Such issues can create flooding conditions, and that is not accounting for the problems associated with burn scars in the area, where dirt acts like cement and water rolls right off the top instead of being absorbed by vegetation and such.
Taddeucci said after Wednesday's storm, there was some street flooding and sand or gravel washouts, which is typical for a strong thunderstorm. His team had only heard of street and multi-use path flooding from Wednesday.
“We have a maintenance manager, and we have crews that are on standby. If something dramatic happens, they're prepared to go out and clear roadways and things like that. We coordinate with the county emergency management agency, and they give us weather alerts, and the Mile High Flood District does as well," said Taddeucci.
Marc Painter was walking his dog along the Boulder Creek Path on Thursday. He said he's lived in Boulder since 1978 and calls it a special place, but knows all too well how temperamental the weather can be.
“There's trepidation when you're a Boulder resident. We know of the injuries that have happened to people, and we know the loss of property that's happened here," Painter said. “They have done a lot to mitigate the risk here, and so while people are very careful and a little concerned, it's worth it. It's still worth living here.”
Painter said his son's home in south Boulder did experience some flooding in the basement on Wednesday night.
For more information on how to prepare for floods in Boulder, visit BoulderFloodInfo.net.
Meanwhile in Englewood, a massive Flood Reduction Project has been underway since a woman died in a 2018 flash flood on S. Acoma Street.
The director of Public Works for the City of Englewood, Maria D'Andrea, said the flood led them to investigate how the storm sewer system was and was not working in order to learn where they needed to invest to improve it.
“We did a citywide flood prone study to see where those areas were. So, there have been some studies done in the past, but nothing really comprehensive," D'Andrea said. “We wanted to look at not just the area that was affected by the 2018 storm, but actually the entire city. And so what we came up with was a prioritized list of projects."
Specifically in the area that flooded, D'Andrea said the city has enlarged or replaced existing storm sewer pipes while adding inlets or catch basins on corners to allow more water to flow into the system faster.
“Divided up this project specifically into three phases. We've completed two of those. The previous phase two was just completed a couple months ago, and the third phase will be done next year in 2023," D'Andrea said.
Starting next year, the City of Englewood will begin working on a large stormwater detention pond which will allow for more water to be stored before it is sent to the South Platte River. In total, the project is expected to cost around $23 million and is funded by stormwater utility fees.
Those living on S. Acoma Street who experienced the flood in 2018 understand why the construction was needed.
“You have to be prepared," said Linda Storey, who was home when the flood happened. “Always have backups to your backups. And that's what we should be doing. Backups to your backups in Colorado.”
