Three Stream Projects in Three Weeks !! First one - COW CREEK
Thursday, October 5, 2017 at 8:06PM
john

These design/build projects have been in the works for almost 3 years!  What is both serrindipitous and stressing is that all three projects got "permitted" in August/September and have to be completed by of about November.  My staff and I have been working 8-9 hr days for weeks now!!  Its "feast or famine" as they say about construction!!

"The Works" meaning design and permitting.  Since these projects are on creeks or rivers designated for endangered Salmon or Steelhead, the permits required include Sec 404 ACOE, NMFS, USFWS, CA DFW, Sec 206 Cultural surveys, Sec 401 Water Quality, and the County of Shasta Grading Permit!!  Just the Ordinary High Water Mark Report required about $5,000 in professional fees, the Biological Report was anothr $3000, the design was actually the least expense to the landowner.  I'm still doing the project accounting but the rock, equipment and labor was about $90,000.  The design and permitting was over $30,000.

COW CREEK, located in Eastern Shasta County, is an incised salmon/steelhead stream that has generally downcut to the bed rock strata.  There is limited bedload available since the system has been "hydromodified" (nearly 150 years of ranching has resulted in "urbanization response" to runoff) and is suceptable to high stormflows which are now restrained in the active channel.  

The project intended to protect the house and garage, perched atop the 30' high bank, by moving the high energy flow vectors away from the bank slightly using redirective methods ( a 20' long Bendway weir and three rock barbs), installing 280' of 4-5' high Longitudinal Stone Toe, carefully installing clean, angular, well-graded stone (that can be placed in the creek without increases in turbidity) which actually protected the existing trees and shrubs that were barely hanging onto the bed rock cracks.  

The challenge was getting down the nearly vertical bank with excavator and then get the 600T of rock down the bank without too much dirt.

Cow Creek during very high flows, Jan, 2017

 

Looking down the bank at start of work, Sept 2017

Rock was end dumped to help form a temprary ramp. Water was used to keep the rock clean.

Lack of room between trees and shop, and the permits requirements restricted the cut to 6 ft.Building upstream bendway weir - to nudge high flows streamward280 LF of LST (5' high using self launching stone*) allows the construction of a flood terrace. The terrace was vegetated with transplants and willow poles/branches arrayed as "live eyelashes".Live Siltation, willow branches pointing outward from LST - the peak of LST at a height near Bankfull discharge elevation, provides roughness as high flows access flood terrace.

The downstream end of project with angled tie back,Looking upstream - one can see how the well graded stone and careful installation of LST and BARBS actually protected most of the existing willows and carex. It is hoped to be easier to achieve our 70% coverage requirement.The upstream Bendway Weir is complete and we also placed some clean spawning gravel.Now we will wait for this winter's storms!!  You can bet we will be out monitoring - stay tuned for more monitoring photos.

By the way, our new website is being planned and developed!! Expect some great changes, including the ability to download video clips, Erosion Draw, BioDraw, the complete or just individual specs from Environmentally Sensitive Streambank Stabilization (ESenSS), or even chapters from Bioengineering Case Studies, 2013, Goldsmith, Gray, and McCullah.

Please let me know what you would like to see more of.   Cheers    John 

 

Article originally appeared on Home of Dirt Time - The Erosion and Sediment Control BMP Show (http://watchyourdirt.com/).
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