“The Coconino County Flood Control District is committed to reducing the impact of post-fire flooding on communities through watershed rehabilitation and flood mitigation,” Flood Control Superintendent Patrice Horstmann said in a statement.

The work, which is expected to take four to six weeks to complete, is designed to mitigate the large amount of sedimentation in the floodwaters from the burnt pipeline. The 2022 fires damaged the Schultz Creek watershed, dramatically increasing the flow and erosion levels of Schultz Creek.

The Flagstaff area suffered significant flooding from the remains of pipeline fires during the 2022 monsoon season, with more than 3,300 tons of ash and sediment flowing into the city’s stormwater infrastructure, including Francis Short Pond.

But Sean Golightly, County Flood District Community Relations Manager, said in a statement that the Schultz Creek effort would be very different from other county-led flood control projects.

Golightly said the work should prove to be much less invasive than other similar projects undertaken by the county to reduce sediment loads within floods.

Golightly said the county has previously employed a strategy known as “alluvial fan restoration,” working with Coconino National Forest and engineering firm Natural Channel Design.

Such alluvial fans have proven successful downstream of other burns, forming a sort of artificial river delta that slows and spreads floodwaters and removes water-carried sediment and debris. Promotes dropping a lot of

However, creating an alluvial fan means flattening and clearing large areas of forest and clearing many trees within the area.

And in the limited and sensitive area of ​​Schultz Creek, Golightly told the Arizona Daily Sun that the county and Natural Channel Design are using different tactics to achieve the same objective.

The strategy is called “plug and spread.”

The plug-and-spread strategy utilizes a series of small dams within the creek bed to slow floodwaters before spreading them again into smaller areas, depositing en route sediment.

“There are several reasons why the Schultz Creek drainage channel is a candidate for plug-and-spread technology. First, it shapes the landscape. said. “But near the bottom, near where Schultz Creek meets ‘Shultz Y’ and the City of Flagstaff Sediment Basin, there is a valley where the natural contours of the land lend themselves to the introduction of plug-and-spread techniques.”

For the plug-and-spread system in Schultz Creek, Golightly said the infrastructure would consist of 11 small dams about three to four feet high.

The new strategy will also better conserve the Schultz Creek area, which is not only a popular area for recreation, but also an unfired habitat for wildlife in the area, Golightly said. .

“We are able to strategically place plugs and drive through trees to minimize disruption,” Allen Hayden, president of engineering firm Natural Channel Design, said in a statement.

Still, Golightly cautioned that the work wouldn’t completely change the area. However, when compared to creating an alluvial fan, “the plug-and-spread technique is less impactful than alternative technologies while providing sediment reduction and supporting the functioning of the downstream stormwater system.”

The Schultz Creek project was the first to use the technology to respond to post-fire flooding around Flagstaff, but Golightly said the technology is not new.

In a statement, Hayden said the strategy was first popularized by the Forest Service to restore perennial swamps and meadows affected by overgrazing.

In fact, the technology was used to do just that in the Coconino National Forest in Long Valley near Clint’s Well, where grazing had degraded the grassland ecosystem, Golightly said.

“We’re kind of on steroids. [in Schultz Creek] And we’re going to use that to create an alluvial fan system,” Hayden said in a statement.

Plug-and-spread infrastructure is only the first phase of flood mitigation work in the area under the pipeline burn.

The second phase of restoration of the Schultz Creek watershed is scheduled to take place later this year. This includes erosion reduction measures further upstream in watersheds that serve as important sediment sources for downstream flows.

“Rehabilitation of the forest watershed, like that under construction in the Schultz Creek watershed, is a game-changer in reducing the impact of sediment and debris overwhelming downstream stormwater systems,” said Flood Control District Manager Lucinda Andreani. rice field.

Funding for this project comes from the Forest Service through Congress-approved funds.

The $5.4 million Schultz Creek project is just one part of an approximately $90 million flood mitigation project to other flooded areas affected by the pipeline fires.

Golightly said the county is also considering flood control activities within the government tank basin and the plug-and-spread strategy could be used again in the area.

Schultz Street will be closed to motor vehicle traffic for the duration of the project, which is expected to last four to six weeks. The road will remain open to hikers, cyclists and equestrians, but approximately 800 meters of Chimney Trail will be closed to all users.

Still, county and forest officials say residents and recreational activists should be cautious near construction sites because of the presence of heavy machinery in the forest and on roads.