Continuous Berm Bendway Weirs and Vanes
This demonstration and training
workshop was intended to 'test' the feasibility and efficacy of utilizing
sand-filled geotextiles to build re-directive structures. These can be a cost-effective
alternative to rock for sand bed streams when rock or large woody debris material
is unavailable.
Ninnescah River near Kingman, Kansas (40 miles
West of Witchita)
|
The Continuous Berm Machine (CBM) has a hopper
which is filled with sand or aggregate. Note roll of filter fabric on front.
|
The CBM is pulled forward with a truck or tractor and a continuous sand-filled geotextile encapsulated berm is produced. |
|
Bags were made up to 30' long.
|
John McCullah demonstrates his favorite new sport... Geoberm bag wrestling, necessary to close the ends of the "wild" bags. |
These pictures show a 3-day
hands-on workshop sponsored by the Kansas State Conservation Commision
(KSCC).
Phil Balch coordinated the workshop with the assistance of Brock Emmert,
KSCC and Rick Davis, Kansas
Department of Health and Environment. David
Derrick, USCOE, Vicksburg, MS and John McCullah, Salix Applied Earthcare
in Redding, CA, were the invited instructors.
Phil Balch developed a "spreader bar" and straps for picking up bags. |
|
|
|
Placement for Bendway Weir |
Keyway into bank about 6'. |
| Sacramento Watersheds Action Group (SWAG) donated the CBM and KSCC paid for transport and all materials needed. | |
|
The bridge downstream is at risk if the lateral
migration is not arrested. This is a good site for a re-directive
approach ( vs. resistive).
View downstream from Bendway Weir. The last bendway weir is intended to "direct" the flows, in this case through the middle of the bridge. |
|
David Derrick demonstrates planting of willow poles as "live siltaion" technique. |
|
|
|
|
|
| The 'geo-berm' bendway weirs and vanes were keyed approximately 2m (6') into the bank. The keyway locations were further reinforced by pole planting, brushlayering, and 12-16' long geoberm bags mounted parallel to flow line. | |
John McCullah demonstrates proper brushlayering installation. |
|
|
|
Weir crest was about 2' high. |
Filling in the Keyway
|
| Brushlayering with geo-berm reinforcements has proved extremely sucessful in other projects, like Sulphur Creek in Redding, CA and streambank protection and landslide repair in Chapman Creek, Sechelt, B.C. These keyways were constructed similiar to reinforced soil fill. McCullah, who is a member of the Erosion Control Patrol, supervises biotechnical work! | |
Brushlayered reinforced fill used from 'Bankfull' to 'Top of Bank'. |
|
|
|
| John McCullah recommends "watering in" brushlayering construction to ensure compaction and hydration of plant materials. | |
Willow trimming. |
Willow soaking (Very important!!) |
Willow harvest. |
|
|
Vane Construction
|
|
|
|
|
|
|
|
| These "sandbag"
vanes were modified so they were flat crested (as opposed to other
vanes that have a sloping crest). These trial vanes were 4-5
bags wide at the bottom, about 35' long, and angled 30° upstream
from bank tangent. |
|
|
|
At
the upstream end of the project (bend) a vane was installed to help
re-direct the flows into the bendway weir "field". The bendway
weirs are intended to capture the flows, control the flows through
the bend and the last weir is to direct the flow through the middle
of the county road bridge. Professor Tim Keane, KSU, John McCullah,
Salix Applied Earthcare, David Derrrick, USCOE -Vicksburg, MS, Phil
Balch KSCC, and volunteers help guide the geoberms into place. |
|
Professor Tim Keane looks at the completed vane. |
|
|
|
Now it is
up to the vegetation, land management (cattle exclusion), and the
establishment of a healthy riparian buffer zone to do the job as the
geoberm bags degrade with time. |
|
