Ada County and Boise River Flood Control District crews Friday installed a 600-foot flood diversion tube along the Boise River—to keep water in the river and away from neighborhoods in Eagle and Garden City.
Ada County engineers noticed earlier this week the high and swift water eroded some low-lying spots of riverbank where the Boise River splits into the north and south channels at the head of Eagle Island, according to an Ada County facebook posting.
That area also happens to be just east of the Sunroc gravel pit –- the biggest area of concern for possible flooding for the last two months.
The 4-foot-tall, 4,000-foot-long barrier installed by the Army Corps of Engineers stands between the gravel pit and the river.
But, according to officials, the new 600-foot-long flood diversion tube -– essentially a 3-foot-tall water-filled industrial-strength plastic/resin/fabric balloon —- is going to provide another piece of protection.
Meridian-based AIRE Industrial built the flood prevention tube.
Ada County and Boise River Flood Control District 10 split the $26,000 cost to create and install the tube, which is reusable.
Work crews spent Friday afternoon installing the tube and filling it with water from the river. Each section is 40-foot-long and weighs 24,000 pounds when filled with water, according to the posting.
It’s installed just east of the HESCO barrier on the south riverbank and is designed to prevent water from going over low spots and into the large farm field next to the pit.
“Don't think of the flood diversion tube as a levee. Think of it is as an industrial-strength riverbank that won’t be eroded by swift floodwater,” the posting stated
The main variable in the flood equation for the next few months is the weather –- and the forecast through the end of April is good. If the weather remains cool -- especially in the mountains –- and the wall of the pit doesn’t collapse, the prospect of major flooding is reduced.