POPLAR RIVER, LUTSEN, MN. SEPARATING THE MEGA-SLIDE FROM THE RIVER (AND MORE) By the stream dream team

Stream stabilization/restoration: Conceptually we will separate the stream from the hill, and in the channel we will make the inside of the bend smoother and the outer section of the stream rougher.

Stream stabilization/restoration methods: A Keyed, Minimal, Toe-Down Continuous Natural Boulder Revetment with Integrated Vegetation Combined with an Engineered Vegetated Mini-Swale combined with Bendway Weirs with pre-dug scour holes forming a pool-riffle-pool regime toward the inside of the bend with boulder fields between the Bendway Weirs. {Exhale here}

Stream Project Functions: Fully functioning both hydraulically & environmentally. Multiple protection redundancy. Revetment provides direct armor protection. Bendway Weirs and boulder fields move scour & thalweg away from attacked bank, with velocities reduced within the Bendway Weir field & boulder fields & on outer bank. Vegetation roughness reduces near-bank flow velocities. Roots strengthen bank & bind soil. Mini-swale captures up- slope colluvium from eroding slope.

PRE-PROJECT PHOTOS by Dave Derrick AUGUST 13, 2007 (Lowest flow in almost 30 years)

Approximately 200 ft US of the project, looking US Derrick lowest flow in 30 yrs

Looking DS at the project, upper project limit is at red line

Derrick Looking at Mega slump. Note undercut mature veg. None of this will be fixed

Derrick lowest flow in 30 yrs Looking DS. The DS end of the mega slump.

Derrick lowest flow in 30 yrs Looking US. Larger bed material on inside of bend will be relocated to the outside of the bend.

THE PLAN

Stream Project Functions: Bendway Weirs move scour & the thalweg away from attacked bank, with velocities reduced within weir field & on bank. Vegetation roughness reduces near-bank flow velocities. Roots strengthen bank & bind soil. Mini-swale captures colluvium.

Mega- Slump Stream Project Planform Mega Slump Bridge Bendway Weir Keys Pre-dug Scour Holes Boulder Revetment Mini Swale Transplanted Veg

SUITABLE STONE Stone used for toe protection & boulder fields was either natural stone from the stream or rounded medium-sized boulders in the 1,500 to 2,000 pound class. Stone for the Bendway Weirs were extremely large rounded boulders, most from the quarry, typically 4 ft by 5 ft by 6 ft. Stone for keys was a mix of native medium boulders, very large rounded boulders from the quarry, & gravel-cobble-small boulder “choke” stone from the stream.

CONSTRUCTION PHOTOS by Dave Derrick and Jay Michels AUGUST 5-8, 2008

CONSTRUCTION PIX OF THE KEY FOR BENDWAY WEIR # 1

A KEY HAS ONE MAIN JOB, TO CONNECT THE RIVER TRAINING STRUCTURE TO THE REST OF THE WORLD (DON’T LET THE STREAM GET BEHIND {FLANK} RIVER TRAINING STRUCTURES)

Stream stabilization/restoration: All keys will be trenched perpendicular to the stream into the bank. One side of each key trench will be lined with adventitious rooting willow poles (harvested locally). All keys will use a gravel filter (harvested from the stream), with the key constructed of a mix of monster boulders & well-graded stone (from both the stream and quarry). Stone will then be choked with soil & seeded.

Cross-section for keyway Detail for keys for the Bendway Weirs & the Minimal Stone Toe Protection

Jay Michels cut about 1,000 willow from near the sewage treatment ponds at the top of the hill for planting within the project. CONSTRUCTION-POPLAR MEGA-SLUMP-PIX BY JAY MICHELS 8/08

Place Willow Poles against one side of the trench Detail for keys for the Bendway Weirs & the Minimal Stone Toe Protection Granular filter

Dave Derrick in key trench placing large willow poles on DS side of trench CONSTRUCTION-POPLAR MEGA-SLUMP-PIX BY JAY MICHELS 8/08 Deeply planted willows oriented perpendicular to flow will act as a “Living Dike”, slowing near-bank flow velocities.

Place stone in trench Detail for keys for the Bendway Weirs & the Minimal Stone Toe Protection

Choke stone with gravel (white areas) & water in to settle choke material & water poles Detail for keys for the Bendway Weirs & the Minimal Stone Toe Protection

Robust key starting to look good!! CONSTRUCTION-POPLAR MEGA-SLUMP-PIX BY DERRICK 8/5-8/2008

Backfill and overfill with native soils, then compact (some settling will still occur over time) Detail for keys for the Bendway Weirs & the Minimal Stone Toe Protection

Key complete except for seeding & mulch. Willow poles will be trimmed (approx. 2/3 of pole in ground, 1/3 out of ground). CONSTRUCTION-POPLAR MEGA-SLUMP-PIX BY DERRICK 8/5-8/2008

Seeding was accomplished the day after we left DONE Detail for keys for the Bendway Weirs & the Minimal Stone Toe Protection

CONSTRUCTION PIX OF BENDWAY WEIR # 1

Dave Derrick setting the upstream angle of the Bendway Weir #5 (20 degrees upstream from perpendicular, or in other words 70 degrees from the bank). All Bendway Weirs were angled 20 degrees upstream. CONSTRUCTION-POPLAR MEGA-SLUMP-PIX BY JAY MICHELS 8/08

From top of key looking hoe digging into streambed so that large stones for the Bendway Weir can be placed at the proper elevation. CONSTRUCTION-POPLAR MEGA-SLUMP-PIX BY DERRICK 8/5-8/2008

From key hoe placing first stone (that will abut the key that was just built) for Bendway Weir #1. CONSTRUCTION-POPLAR MEGA-SLUMP-PIX BY DERRICK 8/5-8/2008

Bendway Weir will be angled toward trees behind hoe bucket. CONSTRUCTION-POPLAR MEGA-SLUMP-PIX BY DERRICK 8/5-8/2008

LET’S LOOK AT, & ALL AROUND, BENDWAY WEIR #1

Looking constructed mini-weir & Bendway Weir #1. Constructed boulder field to left & pool-riffle-pool complex on right side of channel. CONSTRUCTION-POPLAR MEGA-SLUMP-PIX BY DERRICK 8/5-8/2008

Looking constructed mini-weir & Bendway Weir #1. Note constructed boulder field & pool riffle-pool complex on right side of channel CONSTRUCTION-POPLAR MEGA-SLUMP-PIX BY DERRICK 8/5-8/2008

Looking straight at Bendway Weir #1. Jay shooting as-built elevations. Note complex flow. CONSTRUCTION-POPLAR MEGA-SLUMP-PIX BY DERRICK 8/5-8/2008

CONSTRUCTION PIX OF SEVERAL SECTIONS OF THE LONGITUDINAL STONE TOE PROTECTION

Minimal Toe-Down Continuous Natural Appearing Boulder Revetment: Large & small boulders from stream & quarry were placed to form a continuous longitudinal revetment constructed to a height equal to the Q-1.5 flow event plus 2.75 ft (minimum). Revetment has ft long vegetated stone keys that tie into the bank. Keys will be located at the end of each Bendway Weir. Bendway Weir spacing varies from 41 to 79 ft.

CONSTRUCTION-POPLAR MEGA-SLUMP-PIX BY DERRICK 8/5-8/2008 A smooth path was cleared on the left side of the channel so that equipment could traverse the length of the project. This stone was placed in the right side of the channel.

THE MEGA-SLUMP FAILURE ON THE POPLAR RIVER, MN 1 of 8 Stream channel Eroding bank

2 of 8 Existing earth loosened & some soil-gravel added in preparation for planting. THE MEGA-SLUMP FAILURE ON THE POPLAR RIVER, MN

3 of 8 Willow poles will be laid against the bank. Basal ends should be in vadose zone (capillary zone ) Willow pole plantings (in bunches) at intervals

At intervals soil was loosened, willow poles were placed against the bank & soil placed over the lower half of the willow poles. CONSTRUCTION-POPLAR MEGA-SLUMP-PIX BY DERRICK 8/5-8/2008

4 of 8 Rounded boulders from both the stream & quarry will be used as a continuous longitudinal revetment. THE MEGA-SLUMP FAILURE ON THE POPLAR RIVER, MN

Looking the first section of longitudinal toe we constructed. It is too uniform. We will deconstruction this section & build in more chaos !!!!! CONSTRUCTION-POPLAR MEGA-SLUMP-PIX BY DERRICK 8/5-8/2008

Looking the smooth stone revetment in foreground & more chaotic stone toe immediately past the very large boulder CONSTRUCTION-POPLAR MEGA-SLUMP-PIX BY DERRICK 8/5-8/2008

5 of 8 THE MEGA-SLUMP FAILURE ON THE POPLAR RIVER, MN Mini swale can catch colluvium from eroding upper bank

Looking the mini-swale landward of the crest of the toe stone that will capture mass wasted material (colluvium) from the unimproved mega-slide. CONSTRUCTION-POPLAR MEGA-SLUMP-PIX BY DERRICK 8/5-8/2008

6 of 8 THE MEGA-SLUMP FAILURE ON THE POPLAR RIVER, MN County Soil & Water is considering planting 200 rooted stock plants on the Mega-Slump

6 of 8 THE MEGA-SLUMP FAILURE ON THE POPLAR RIVER, MN 8 Bendway Weirs, each 2 boulders wide, 15 to 22 ft long, spaced 42 to 79 ft apart

Looking the stone toe & Bendway Weirs, boulder field not added yet. CONSTRUCTION-POPLAR MEGA-SLUMP-PIX BY DERRICK 8/5-8/2008

CONSTRUCTION PIX OF RANDOM SCATTERING OF BOULDERS TO CREATE THE BOULDER FIELDS BETWEEN THE BENDWAY WEIRS

Looking boulder flying though air CONSTRUCTION-POPLAR MEGA-SLUMP-PIX BY DERRICK 8/5-8/2008

Looking the big boulder splash CONSTRUCTION-POPLAR MEGA-SLUMP-PIX BY DERRICK 8/5-8/2008

Stream Project Functions:::::::: Longitudinal toe stone provides scour protection Toe stone protection completely separates stream from Mega Slump Willow poles provide vegetative roughness, increase height of “soft protection”, shades stone & water, & has many wildlife functions {everything from carbon input to structure cover to insect production, beneficial to pollinators, etc.} Mini-Swale provides a storage area for colluvium from Mega Slump Bendway Weirs increase stream roughness, reduce toe scour, provide diversity & complexity of depth, velocity (horizontal & vertical) & substrate, plus they move the thalweg away from the toe of the eroding bank. The dug pools at the ends of the Bendway Weirs provide mini pool- riffle-pool sequences throughout the bend. Boulder fields provide additional roughness, plus a “natural” look

CONSTRUCTION COMPLETE INDIVIDUAL SHOTS OF KEYS & BENDWAY WEIRS #1-8

Looking at short Bendway Weir US of Bendway Weir # 1. All construction appears quite natural!!! CONSTRUCTION COMPLETE-POPLAR MEGA-SLUMP-PIX BY DERRICK

Looking at Key # 2 and Bendway Weir # 2. CONSTRUCTION COMPLETE-POPLAR MEGA-SLUMP-PIX BY DERRICK

From the Mega-Slump, looking Bendway Weir # 2. CONSTRUCTION-POPLAR MEGA-SLUMP-PIX BY DERRICK 8/5-8/2008

Looking at Key # 3 and Bendway Weir # 3. CONSTRUCTION COMPLETE-POPLAR MEGA-SLUMP-PIX BY DERRICK

Watching the river flow, Key #4 & Bendway Weir #4 CONSTRUCTION COMPLETE-POPLAR MEGA-SLUMP-PIX BY DERRICK

Looking at Key # 5 & Bendway Weir # 5. Constructed riffle mimics pre-project condition CONSTRUCTION COMPLETE-POPLAR MEGA-SLUMP-PIX BY DERRICK Pre-project riffle

Looking at Key # 6 & Bendway Weir # 6. Note veg in key CONSTRUCTION COMPLETE-POPLAR MEGA-SLUMP-PIX BY DERRICK

Looking at Key # 7 and Bendway Weir # 7. CONSTRUCTION COMPLETE-POPLAR MEGA-SLUMP-PIX BY DERRICK

Looking at Key # 8 and Bendway Weir # 8. CONSTRUCTION COMPLETE-POPLAR MEGA-SLUMP-PIX BY DERRICK

CONSTRUCTION COMPLETE (going from upstream to downstream) Photos by Dave Derrick AUGUST 8, 2008

Looking DS. Boulder field to left, dug pools & riffles on right CONSTRUCTION COMPLETE-POPLAR MEGA-SLUMP-PIX BY DERRICK

Looking from BW #2 upper end of project. CONSTRUCTION COMPLETE-POPLAR MEGA-SLUMP-PIX BY DERRICK

Looking toe stone & Bendway Weirs CONSTRUCTION COMPLETE-POPLAR MEGA-SLUMP-PIX BY DERRICK BW#2 BW#3 BW#4

Bendway Weir #3. Note flow around weir & through boulders. CONSTRUCTION COMPLETE-POPLAR MEGA-SLUMP-PIX BY DERRICK BW#3

CONSTRUCTION COMPLETE-POPLAR MEGA-SLUMP-PIX BY DERRICK Looking toe stone & Bendway Weirs BW#2 BW#3 BW#4

Looking at constructed natural appearing random boulder field (foreground) & random chaotic stone toe CONSTRUCTION COMPLETE-POPLAR MEGA-SLUMP-PIX BY DERRICK

Looking pool & colorful riffle CONSTRUCTION COMPLETE-POPLAR MEGA-SLUMP-PIX BY DERRICK

Watching the river flow, looking Bendway Weir # 5. CONSTRUCTION COMPLETE-POPLAR MEGA-SLUMP-PIX BY DERRICK

a riffle & longitudinal stone toe protection. Note pools & rifles. CONSTRUCTION COMPLETE-POPLAR MEGA-SLUMP-PIX BY DERRICK

Looking Bendway Weirs # 7 & # 8 & stone toe. CONSTRUCTION COMPLETE-POPLAR MEGA-SLUMP-PIX BY DERRICK

Looking Key #8 (with veg) & BW #8. Note pools & flow at end of weir CONSTRUCTION COMPLETE-POPLAR MEGA-SLUMP-PIX BY DERRICK

9 MONTHS AFTER PROJECT COMPLETION Photos by Jay Michaels May 9, 2009

9 MONTHS LATER-POPLAR MEGA-SLUMP-PIX BY JAY MICHAELS From top of Mega Slump, looking US at entrance conditions into project. White water DS of each Bendway Weir shows weirs are working as designed.

From top of Mega Slump, flow right to left. White water DS of each Bendway Weir shows weirs are working as designed (dissipating energy, producing mini pool-riffle-pool sequences). Thalweg realigned to a location off the stream ends of the weirs. Inner channel flow reduces bank stress along Mega-Slump. 9 MONTHS LATER-POPLAR MEGA-SLUMP-PIX BY JAY MICHAELS

From top of Mega Slump, looking DS at second half of project. Bendway Weirs working well, slow water near left bank, thalweg realigned to a location off the stream ends of the weirs. Exit conditions well behaved.

WE ARE DOG TIRED, THIS PROJECT IS DONE !! Cleophus Speed Elvis Derrick

to the doubters & nay-sayers, the old raspberry, this project is working!!