11-25-2019
By Michael Raffety
El Dorado Irrigation District has three big projects going simultaneously, all of which I recently had an opportunity to visit and hike around.
The first one I visited was Flume 47C, a 150-foot-long $1.9 million project that is being done 90 percent by EID construction crews and some temporary hires. The canal had already been dug out. I arrived by a very roundabout and sometimes very bumpy route due to a county paving project on the new Sad Bridge. The EID construction crew was cutting out rebar sections and tying them together into sloped U sections that would be mounted in the canal as reinforcement as a shotcrete crew would come to line the canal bottom and sides.
Fabricating the rebar sections was a new challenge for the EID construction crews, according to Dan Gibson, Hydro Manager. They seemed to be working seamlessly.
Expectations are this flume project will be finished in December.
The bigger project is Flume 44. This is the second and final year for this $14.6 million project by contractor K.W. Emerson. Flume 44 is one of the most challenging wooden flume sections, one which I would call rickety. It is very tall and crosses a slide area.
The plan by EID engineers executed by K.W. Emerson during the annual canal outage changed most of this flume to a U-channel steel reinforced canal with a wide sidetrack for equipment. The last tallest section has been replaced by Ultra Blocks. Flume 44 is 476 feet long. Last year Emerson installed 1,800 feet of U-channel canal and a fairly wide bench for machinery. With the Ultra Blocks replacing Flume 44’s timber superstructure there is now a bench suitable for machinery and the U-channel canal is close to being connected to the wooden Flume 45.
The Emerson company has a sophisticated articulated dump truck. In other words, the driver drives toward the loader at which point the whole tracked wheel dump truck spins in place without the tracks moving so the driver is facing a different direction and the dump container is facing the loader. It’s a very efficient way to move dirt out of the U-channel.
The district’s absolutely biggest project is the Forebay Dam safety project. When I visited Forebay Dam it was one foot from achieving its maximum height of 10 feet higher than its original height. That extra height will provide six days of water supply to Reservoir 1. Reservoir 1 in Camino serves water all the way to El Dorado Hills for a good portion of the year. The two key safety features of the dam are a buttress added to the dam to strengthen it and a special filter between the dam and the buttress that drains off any seepage. Two boxes collect any seepage and near the foot of the dam are channeled it to a pump house that returns the water to the reservoir.
The $25 million dam project is on its third and final year. The first year primarily included logging the area where the qualified buttressing material will come from. Additional benefits of the project include an emergency overflow area and a moveable gate for the penstock. EID crews inspected, cleaned and replaced some rivets and then encased in concrete the penstock coming from the dam as it connected to a penstock house.
Also executed by the contractor is a new concrete and riprap spillway that brings flume water into the reservoir. Riprap was also added to the inside of the dam to prevent erosion. Additionally, trees were logged around the perimeter to account for the higher dam and a trail has been roughed out.
The borrow pit has been largely reclaimed and includes erosion control.
One interesting sidelight was provided by an EID inspector on the job. He had noticed some blood down at the bottom of a hill. He put up a game camera and found a deer had been dragged down to a wooded area. Later two mountain lions came back to the carcass and then a bear finished it off.
Wow! It’s wild out there. That reminds of the time Krysten Kellum and I followed cougars tracks through the snow as we drudged off to see precast flume sections being glued together in a heated tent. We were very alert.
michaelraffety 