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LOCKED LOGS (LL)
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THIS METHOD IS A DAVE DERRICK DISCOVERY (DDD)
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The "Locked Limb/Locked Log" Concept Consists of entire trees large or small, and/or Small Woody Debris (SWD) consisting of limbs, limbs with leaves, sections of small tree trunks, tree tops, etc. anchored within or placed under structures, with limbs/logs protruding into deeper scoured areas to provide in-stream cover, vertical and horizontal structure, hydraulic roughness, & areas of refugia. Can be either hand- or machine-placed Locked Limbs are typically less than 2” inches in diameter, Locked Logs are greater than 2 inches in diameter
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Courtesy of Ecology and Environment, Inc.
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Analysis of existing downed logs in the stream system should be undertaken, & the LOCKED LOGS placed at similar angles (typical angles are from 15 to 35 degrees downstream relative to the bank). The root wad is positioned upstream. Study nature!!
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MILL BROOK, SALISBURY, NEW HAMPSHIRE PROJECT CONSTRUCTED July 7-16, 2010
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Trees were angled downstream 30 degrees from the bank with the root wads upstream against the eroding bank Road Locked Logs
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Stone is then loaded on the Locked Logs which “locks” the log in place. Best to have a root wad attached to the log which acts as a spread anchor. Road Locked Logs LOCKED LOG provides hydraulic roughness & aquatic habitat
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HIGH WATER-Site #2-Looking US @ 13 Locked Logs providing chaotic structure habitat & in-stream refugia. Thalweg bubbles near inside of bend. HIGH WATER-MILL BROOK, NH-PIX BY DAVE DERRICK 7-14-2010
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Flow Locked Logs Stone toe protection Place logs on bed of stream, angle log downstream at the appropriate angle, then place stone on the Locked Logs which “locks” the log in place. Root wad acts as a spread anchor.
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GOAL & FUNCTION-BASED DESIGN FOR RIPARIAN & STREAM SYSTEMS THE EIGHTEENMILE CREEK PROJECT CONSTRUCTED AUG-SEPT 2003 by Dave Derrick
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EIGHTEENMILE CREEK IS A SUBURBAN, GRAVEL-COBBLE BED, POOL-RIFFLE-POOL REGIME STREAM IN A DEEP V-SHAPED VALLEY
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A downstream reference wood jam for Locked Limbs/Locked Logs. Always try to imitate nature & natural functions Pix by Derrick
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Floating the “footer” log in place
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Pix by Derrick “Footer” log in place with Locked Logs placed perpendicular & over top of footer log.
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Locked Logs now “locked” in place with stone Pix by Derrick
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Row of Locked Logs Pix by Derrick
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Locked Logs Pix by Derrick
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Locked Limbs & Locked Logs one year later, June 24, 2004 Pix by Derrick
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THE IMPORTANCE OF SMALL WOODY DEBRIS, LEAF LITTER & LEAF PACKS Dead things are good things, and these are typically present in nature and reference reaches, but sometimes completely forgotten during “restoration” projects Can be extremely important in starting the food web, for cover (horizontal and vertical structure) for juvenile fishes, and substrate for benthic macro invertebrates Should be added to the stream during restoration in appropriate amounts and spacing based on analysis of similar reference reaches After appropriate analysis, downed trees and/or brush piles might also be placed in riparian areas BEWARE: Large debris piles at bridges or other constrictions can lead to maintenance nightmares & carbon-starved downstream reaches
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Locked Logs for McKinstry Creek, Delevan, NY This a gravel-cobble bed stream, with a constant slope of 1% in the project area, rural, first order headwater stream, with a pool-riffle-pool regime.
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McKinstry Creek, Delevan, NY This was a complete stream and floodway realignment. Constructed June-July 2005. The stream had been straightened prior to 1939 (probably to accommodate the construction of Gooseneck Road)
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McKinstry Creek near Delevan, NY, 5-18-2006, flow left to right Existing planform (red line)
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In the 1939 aerial photos the stream had already been straightened & was parallel with the road. Where had it been?? How long was it?? No one knows. Existing planform (red line)
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The stream needs to be longer and/or rougher but we are hemmed in by the road & the hill. Green line is toe of hill We will have to increase the amplitude of the vertical sine wave (extreme verticality)! Gooseneck Road McKinstry Road
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McKinstry Creek near Delevan, NY, 5-18-2006, flow left to right New channel planform (blue line)
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The “Shadow Wall” Pool with Locked Logs and a large transplanted multi- trunk Alder for shade
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Channel dug to invert depth, 5 ft below surrounding land
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Not as easy to build as it looks
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“Shadow Wall” stones, A-axis of stone placed perpendicular to flow
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Half-Dense Riprap with Shadow Wall Toe Stone with Vertical face The toe stone is designed to cast a shadow into the deepest section of the channel
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Half-Dense Riprap with Shadow Wall Toe Stone with Vertical face Shadow area
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Half-Dense Riprap with Shadow Wall Toe Bottom of stone placed deeper than maximum scour in pool Neither the shadow wall or the half-dense riprap is self-adjusting, both are foundation dependent Stone for half-dense riprap should be embedded 50% and cover less than 50% of the bank area Plantings (including vines) should be integrated into the half-dense riprap
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Locked Logs placed in 3 ft deep pool
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Locked Log locked down with “Shadow Wall” stones
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Hand rolling a stone to lock down a Locked Log
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All aquatic habitat features are designed to be submerged during base flow conditions
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Looking US at pre-dug pool with Shadow Wall & Locked Logs (everyone’s fav pool)
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CASE STUDY: GROUNDBREAKING BANK PROTECTION MISSOURI RIVER @ LEWIS & CLARK REGIONAL WATER SYSTEM, VERMILLION, SD.
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MISSOURI RIVER @ LEWIS & CLARK REGIONAL WATER SYSTEM, VERMILLION, SD. Very large river Congressionally designated as a Wild & Scenic River in 1978. This is a recreational reach. Can flood for months at a time Ice and ice damage are issues 5,120 ft of protection on the left descending bank US of the Highway 19 bridge, Vermillion, SD. Banks 25 ft tall, very fine grained sand, almost fluff Pool-riffle-pool regime, slope one ft per mile
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FUZZY EXTREME LOCKED LOG Cedar tree with lots of branches
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Looking US. A cedar Fuzzy Extreme Locked Log CONSTRUCTION-MISSOURI RIVER @ L & C-DERRICK-NOV 15, 2007
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Looking US. Placing the Fuzzy Extreme Locked Log in trench CONSTRUCTION-MISSOURI RIVER @ L & C-DERRICK-NOV 15, 2007
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Looking US. Fuzzy Extreme Locked Log is locked in place with toe stone. Crest width on toe stone is 10 ft wide. 113 trees spaced 50ft apart were placed. Trees were 65 to140 ft long, with 15 ft of trunk & the root wad buried under the stone toe. Angle downstream varied from 70 to 30 degrees. CONSTRUCTION-MISSOURI RIVER @ L & C-DERRICK-NOV 15, 2007
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Looking US. Smoothing choke soil on the 10 ft wide toe stone crest with the Bobcat. CONSTRUCTION-MISSOURI RIVER @ L & C-TERRY STOLTENOW-12/5/07
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THE ENVIRONMENTAL AND HYDRAULIC ATTRIBUTES GO HAND-IN-HAND ON THIS PROJECT
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Looking US @ self-adjusting toe stone & Extreme Locked Logs, natural bank US. CONSTRUCTION-MISSOURI RIVER @ L & C-DERRICK-NOV 15, 2007
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EXTREME LOCKED LOGS WITH ICE
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ICE MANAGEMENT FOR STABILIZATION/RESTORATION PROJECTS Increase roughness of the bank and near-bank aquatic area!!! Ice will form first in slow water Ice will be thickest in the slower water Next the entire stream has an ice cover Then the spring ice-out occurs The thickest ice near the bank will stay put so that plants are not sheared & smaller stones are not plucked
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Ice surrounding LL fends off moving ice floes. Thickness of ice shows flow velocity differentials CONSTRUCTION-MISSOURI RIVER @ L & C-DERRICK-DEC 11, 2007
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Looking DS at ice buildup around the Locked Logs. CONSTRUCTION-MISSOURI RIVER @ L & C-DERRICK-DEC 11, 2007
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Looking DS at toe stone & Extreme Locked Logs. CONSTRUCTION-MISSOURI RIVER @ L & C-DERRICK-NOV 14, 2007
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THE POWER OF LOCKED LOGS ON THE MISSOURI RIVER DURING THE GREAT FLOOD OF 2011.
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39-40 Months After Project Completion GREAT FLOOD OF 2011 AERIAL PHOTOGRAPHS Different dates
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GREAT FLOOD OF 2011-Looking DS. Clearly visible foam line indicates the influence of the Locked Logs, (slower water nearer bank). Logs are submerged at least 8 to 10 ft. 38 MONTHS LATER- MISSOURI R.@L & C-FROM TED HALL 6-29-11
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40Months After Project Completion GREAT FLOOD OF 2011 PIX TAKEN TWO FOOT BELOW FLOOD CREST Photos by Derrick JULY 30, 2011
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2 FT BELOW GREAT FLOOD OF 2011 CREST-Looking @ foam line approx. 100 ft. into channel caused by the reduction in flow velocity due to the Locked Logs. Logs 8-10 ft under water. 40 MONTHS LATER- MISSOURI R.@L & C-PIX BY DERRICK 7-30-11
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2 FT BELOW GREAT FLOOD OF 2011 CREST-Looking DS @ foam line delineating the outermost effect of the Locked Logs in reducing flow velocity. Logs 8-10 ft under water. 40 MONTHS LATER- MISSOURI R.@L & C-PIX BY DERRICK 7-30-11
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2 FT BELOW GREAT FLOOD OF 2011 CREST-Looking DS @ debris on bank. All 4 rows of willows under water. No erosion! 40 MONTHS LATER- MISSOURI R.@L & C-PIX BY DERRICK 7-30-11
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HIGH-LOW LOCKED LOGS After watching them perform during the flood, the contractor, Tom Powell, is a big Locked Log fan, so he staggered them high & low to better slow water than if all logs were placed at the same elevation.
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Looking DS @ left bank 4.25 YEARS LATER-Looking DS @ a Locked Log (LL) high in water column. After watching them perform during the flood, the contractor staggered the LL high & low to better slow water than if all logs were placed at the same elevation. 4.25 YEARS LATER- MISSOURI R.@L & C-FROM DERRICK 8-2-2012
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Looking DS @ left bank 4.25 YEARS LATER-Looking DS @ Locked Log installed lower in the water column. High & low logs slow more water & are more effective than all logs at the same elevation. 4.25 YEARS LATER- MISSOURI R.@L & C-FROM DERRICK 8-2-2012
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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!! d_derrick@r2d-eng.com
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