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 @ d_derrick@r2d-eng.com

Enjoy the information!!

Cleophus napping in the sun