SINGLE STONE
BENDWAY WEIRS
SINGLE STONE BENDWAY WEIRS (SSBW) follow all design rules for Bendway Weirs, but are typically constructed of just one very large stone, typically 5 to 7 ft long, 3 to 4 ft wide, angled 70 degrees upstream to the bank, level-crested one ft above base flow water surface elevation, & keyed into the bank. Spacing rarely exceeds 50 ft, SSBW typically are 25 to 35 ft apart.
SSBW are designed to reduce near bank velocities & shear stress, & relocate the thalweg to a smoothed alignment off the stream ends fo the SSBW.
A general rule of thumb for any Bendway Weirs, the shorter the weir, the closer the spacing, the longer the weir, the greater the spacing.
AERIAL VIEW OF STONE TOE PROTECTION WITH SINGLE- STONE BENDWAY WEIRS (SSBW).
THALWEG REALIGNMENT DUE TO SSBW!!
Stone Toe protection
SSBW
SSBW
Thalweg Realigned by SSBW
Original Thalweg
ICE DAMAGE REDUCTION
PROJECT- CHAUTAUQUA
CREEK @ MOUTH
(LAKE ERIE) WESTFIELD,
NYPix by Dave Spann
CHAUTAUQUA CREEK ICE DAMAGE REDUCTION
PROJECT –Near its mouth @ Lake Erie Severe scour from ice & high flow velocities
eroded a 285 ft section of the right descending bank landward 30 ft, resulting in an overwidened section of stream.
Mid-channel sediment bars, shallow areas, & mouth of creek @ Lake Erie clogged, resulting in blockage of fish migration for spawning
No holding areas or habitat for steelhead or salmon
A heavily used public fishing section of stream
Conceptually the project should:
Provide a very smooth, armored, & well-aligned right descending bank
Establish dense upper bank and top bank vegetation for shade, detritus, and reduce the chance of overbank ice jams (picket fence theory)
Move the thalweg 5 to 7 ft streamward of the toe of the bank protection with a series of Single Stone Bendway Weirs spaced 50 ft apart).
Provide in-stream habitat & holding areas for sport fish
Provide a replacement fisherman’s path along top bank
BONUS: Blow out the sediment block at the mouth of the creek (where it empties into Lake Erie)
NEED PLANS & SPECS
Single Stone Bendway Weirs (pegged to bedrock)
Key
Key
Key
Key
Key
Key
Key
Trenched Stone & Stacked Stone WallSloped Stone using “Big Flats” (large 4 ft by 7 ft wide stones)
Flow Realigned
thalw
eg
DRILLING & PEGGING TOE
STONES & SINGLE STONE BENDWAY
WEIRS TO BEDROCK WITH
1 5/8” DIAMETER METAL RODS
Construction June 2006. Looking DS @ 2 hoes jack
hammering a footer trench through solid stone
Pix by derrick
7 ft long, 1 5/8 inch
diameter rebar
rods for pegging stone to bedrock.
Pix by Joe Galati
Pix by Joe Galati
Dave Spann of Chautauqua County
Soil & Water Conservation District with a 7 ft long, 1 5/8 inch diameter rebar. Dave did everything
from writing the grant to providing
extraordinary project management. On time
& under budget!!!!
Construction June 2006.
Looking DS. Drilling 2.5
inch dia. holes to peg stone to bedrock. The 2.5 inch bit
was the only one they had
on hand…
Pix by Joe Galati
Construction June 2006. A good hole in a footer
stone.
Pix by Joe Galati
Construction June 2006. Looking US.
Metal pinning rods not cut off
yet. Pix by derrick
Looking upstream at the
SINGLE-STONE BENDWAY
WEIRS
Aug 31, 2006, looking US at two pegged to bedrock Single-Stone Bendway Weirs (50 ft apart) in the stacked stone wall section.
Pix by derrick
Aug 29, 2006 -high water- Looking US, note dead water near toe & thalweg location near arrow, all
due to the Single Stone Bendway Weirs
Photo by Dave Spann
Looking downstream
at the SINGLE-STONE
BENDWAY WEIRS HIGH WATER AUG 29, 2006
Aug 29, 2006-high water-looking DS
Photo by Dave Spann
Note rooster tail defining right edge of
high velocity water
Aug 29, 2006-high water-Looking DS toward Lake
Erie
Photo by Dave Spann
Another high water flow event.
Mar 14,
2007
Mar 14, 2006. Looking DS. Three
submerged Bendway Weirs can be located due to
surface disturbance.
Thalweg well-aligned streamward of the stream ends
of the SSBW
Pix by Joe Galati
Mar 14, 2006. Looking DS. Close-up of two submerged Bendway Weirs. Slow water near
bank
Pix by Joe Galati
16 MONTHS AFTER
CONSTRUCTION
NOV 2007
Nov 8, 2007.
Looking DS. Base
flow, thalweg off the ends of
the SSBW
Pix by Joe Galati
Project effects downstream at
the mouth (Lake Erie) Feb 7, 2007
Looking DS on Feb 7, 2007 at ice mountains blocking mouth of Chautauqua Creek @
Lake Erie {approx. 700 ft DS of DS end of project}.
Pix from Joe Galati-NYSDEC
Looking DS at ice mountains blown out by concentrated flow from our project. This is approx. 700 ft DS of DS end of project. Mar
14, 2007
Pix from Joe Galati-NYSDEC
This PowerPoint presentation was developed & built by Dave Derrick.
Any questions or comments, call my personal cell @ 601-218-7717, or email @ [email protected]
Enjoy the information!!
Cleophus napping in the sun