By Dave Derrick, Potomologist & VP, River Research & Design, Inc .

1. LONGITUDINAL PEAKED STONE TOE PROTECTION {LPSTP} & LONGITUDINAL FILL STONE TOE PROTECTION {LFSTP} By Dave Derrick, Potomologist & VP, River Research & Design, Inc.

2. SELF-ADJUSTING, SELF-HEALING, BANK STABILIZATION METHODS ARE BEST!!

3. Derrick’s Reference PowerPoints • LECTURE: 04-BIG-RESISTIVE • METHODS: FUNNEL TECHNIQUE • CASE STUDY: CHENUNDA CREEK ROAD PROTECTION, NY; • CASE STUDY: TOLEDO-MIAKONDA-BUILT FALL 2012 • CASE STUDY: MISSOURI RIVER @ LEWIS & CLARK-VERMILLION SD {LFSTP} • CASE STUDY: DUCK CREEK-DAVENPORT IA-LPSTP • CASE STUDY: BELEWS CR-EPA 319-HILLSBORO MO • VIDEO: DUCK CREEK

4. DESCRIPTIONS

5. Description of Longitudinal Peaked Stone Toe Protection {LPSTP} LPSTP is a continuous stone dike placed longitudinally at, or slightly streamward of, the toe of the eroding bank. Cross-section is triangular. The LPSTP does not necessarily follow the toe exactly, but can be placed to form a "smoothed" alignment through the bend. Smoothed alignment might not be desirable from the environmental or energy dissipation points of view . Amount of stone used (1 ton/ lineal ft, 2 tons/ft, etc.) can depend on the height of LPSTP required, volume of stone required to mitigate toe scour, estimated stream forces (impinging flow) on the bank, & flood durations & stages. Bank grading is not always needed (existing vegetation not disturbed).

6. Description of Tie-Backs Tie-backs are short stone dikes (at regular intervals) connecting the LPSTP to the stone key that is dug into the bank. Tie-backs are usually the same height as the LPSTP, or elevated slightly toward the bank end. If tie-backs are long they should be angled upstream to act as Bendway Weirs (if level-crested), or Bank Barbs (if crest is sloped).

7. Functions of No Mow Stones (NMS) “No Mow Stones” are designed to effectively keep riparian, wetland, near stream, & other wild areas from getting accidently mowed. If mowed, many of these important & expensive areas never recover functionality. One study in Charlotte, NC. detailed that 26 agencies, governments, & companies mowed right-of-ways within city limits. No mow & no spray signs did not work. St. Louis District Corps of Engineers requires that Now Mow Stones be placed to protect vulnerable areas in stream mitigation banking projects.

8. FUNCTIONS

9. Functions of Longitudinal Peaked Stone Toe Protection • Resists the erosive flow of the stream, only stabilizes the toe, does not protect mid and upper bank areas. • "Smoothed" longitudinal alignment results in improved flow alignment. • Success depends on ability of stone to launch into scour holes formed on the river side of the LPSTP. • Weight of stone in the LPSTP (loading of toe) might resist some shallow-fault geotechnical bank failures. • Captures alluvium & upslope failed material on bank side of structure.

10. HISTORY

11. HISTORY OF LPSTP/LFSTP • One of the more universal bank protection methods. Very versatile, works well in a wide variety of situations. • Pioneered by Vicksburg District Corps of Engineers in the late 1960’s. Probably 300 miles of LPSTP applied @ a rate of 1 to 2 tons/ft on Mississippi small to large sand-silt bed streams. Long history since early 1970’s of nearly maintenance free functionality. Very few failures recorded.

12. APPLICABILITY

13. APPLICABILITY OF LPSTP/LFSTP • Where the bank must be built back out into the stream (realignment of channel or a “false bankline” needed to gain space between stream & object requiring protection) • Construction of & protection for a backfilled vegetative bench or terrace for habitat improvement and/or velocity attenuation) or to increase space between stream & object requiring protection

14. APPLICABILITY OF LPSTP/LFSTP • Where a minimal continuous bank protection is needed. • Good where outer bank alignment makes abrupt changes • Works well in combination with other methods (Hydraulic Cover Stones, Bendway Weirs, vanes, barbs, J-Hooks, and/or Locked Limbs/Locked Logs, and/or bioengineering within the stone {joint planting, Bent Willow Poles} or immediately behind stone {Live Siltation, Living Dikes}, & veg in mid/upper bank areas {brush layering, Slit Brush Layering, transplants, Living Dikes, Dead Dikes, rooted stock or container plants}.

15. DESIGN CONSIDERATIONS

16. DESIGN CONSIDERATIONS FOR LPSTP KEYS • LPSTP must be deeply keyed into the bank at both the upstream and downstream ends and at regular intervals along its entire length. Charlie Elliott’s spacing rules-of-thumb for keys in flat-sloped sand bed water bodies: 50 to 100 ft intervals on smaller streams, 1 to 2 bankfull widths on larger waterways. • Keys at the upstream and downstream ends of LPSTP should not be at a 90 degree angle to the LPSTP structure, but at 20 to 30 degrees to HIGH FLOW. • Keys should go far enough back into the river bank so river erosion & migration will not flank the key & the LPSTP. • Keys should be vegetated if possible. Key length can be extended with vegetation alone in some cases. • Volume of material per ft of key should equal or exceed the volume of material per ft in the LPSTP. Stone max. size & gradation should be the same as the stone used in the LPSTP & Tie-Backs • Minimum key width should be three times the D-100 of the stone used

17. Longitudinal Peaked Stone Toe Protection 20-30 degrees Flow Inner bank Upstream key Outer bank 20-30 degrees LPSTP (black line) Downstream key Both the upstream & downstream keys should be angled 20 to 30 degrees to high flow. All keys are vegetated & soil choked Tie-backs (blue lines) connect the LPSTP to the key. The key, sometimes called the key root or keyway, is dug into the bank. Mid-project keys (red lines) are perpendicular to high flow & connect the tie-back to the bank Key designs for continuous bank protection

18. Longitudinal Peaked Stone Toe Protection (LPSTP) As-built After a couple of high flow events stream has scoured at the toe & stone has self-adjusted Sediment can deposit landward of the LPSTP

19. Johnson Creek, MS. Pre-project, rapidly eroding near-vertical bank {rural, sand bed, slope < 1%, pool-riffle-pool, meandering, incised} Mini case study: 1 of 3

20. Johnson Creek, MS. As-built protection consists of Longitudinal Peaked Stone Toe protection (LPSTP) applied at 1 ton/ lineal ft (3 ft tall) Mini case study: 2 of 3

21. Johnson Creek-LPSTP one year later (note volunteer willow growth) Mini case study: 3 of 3

22. Longitudinal Peaked Stone Toe Protection {installed 1977, picture taken Sept 2003} at Batapan Bogue, Grenada, MS. LPSTP has launched as intended (note steep angle of repose), armored the scour hole as expected, & mature vegetation is assisting with overall bank stability

23. CASE STUDY- Hickahala Creek Pipeline Protection Project at milepost 347.64Tate County, Senatobia, MSConstructed Sept. 2003Longitudinal Peaked Stone Toe Protection {LFSTP} with upper bank paving

24. LPSTP BUILT FROM SELF-ADJUSTING, SELF-FILTERING STONE, EXCESSIVE SCOUR SHOWN As-built cross-section, note angle of repose 1:1.5 to 1:1.25 Reduced height of protection Undercut & launched, original height of protection is reduced Undercut angle of repose is steeper than original

25. Looking US at the entire stream trying to flow underneath the exposed pipeline, the first bend downstream of a long straight stretch is hard to repair, the water does not want to turn!!! This stream put sediment 1,000 ft in a straight line out into the farmer’s field & scoured the field.

26. Area of interest. Flow attack angle

27. LPSTP 5 ton/ft toe LPSTP & bank paving totaled 8 tons/ft on this bank! Bank Paving September-26-2003

28. Hickahalla Creek, Senatobia, MS. Constructed Sept 2003. Looking US at impinging flow impact zone. Note steep angle where LPSTP was undercut & launched (self-adjusted). Several years later this bank is still stable & vegetated April 2006

29. Note steep angle where LPSTP was undercut and launched (self-adjusted) Original angle of repose Launched angle of repose

30. 4 years after construction, very stable, veg growing well LOOKING US, JULY 2004 March 2007

31. 7 years later, bank steep near water but very stable, Veg growing well on 2 ft of deposition on stone, rock has not launched since high flows hit shortly after construction April 19, 2011

32. 3 MINI LPSTP CASE STUDIES

33. Over-launching of LPSTP due to excessive scour, S. Fork Tillatoba Creek, installed 1972, photographed 1998

34. Pix by Wayne Kinney Minimal LPSTP Brushy Creek, IL. Looking DS. About 0.75 ton/ft of self-adjusting stone, which is about the minimum that can be used. Note that contractor worked from top bank & really beat up a lot of the good upper bank vegetation.

35. Transitioning from LPSTP to full bank paving Looking DS on Harland Cr. Tchula, MS, very smooth transition in the downstream direction from one ton/ft LPSTP to full bank paving (tree area)

36. COMBINATIONS OF RESISTIVE & REDIRECTIVE METHODS:CASE STUDY- Duck Creek East of Eastern Avenue, Davenport, Iowa (View the construction video)Constructed June-July. 2008Longitudinal Peaked Stone Toe Protection {LFSTP} with interspaced Short Bendway Weirs & Locked Logs

37. Inner bank 20-30 degrees Flow Outer bank Upstream key Locked Logs 20-30 degrees Downstream key Bendway Weirs at intervals, keyed into the LPSTP. Designed to act as a system to realign the thalweg & reduce velocities near the LPSTP LPSTP with Bendway Weirs & Locked Logs modified from: www.E-SenSS.com

38. FROM DOWNSTREAM LOOKING UPSTREAM AT THE THALWEG ALIGNMENT

39. Looking US @ thalweg realigned by Bendway Weirs & Locked Logs CONSTRUCTION-DUCK CR. E. OF EASTERN AVE. PIX BY DERRICK 7-1-2008

40. Same pix as previous, but with thalwegs delineated. Old thalweg alignment new thalweg alignment CONSTRUCTION-DUCK CR. E. OF EASTERN AVE. PIX BY DERRICK 7-1-2008

41. From DS looking US @ thalweg trace. CONSTRUCTION-DUCK CR. E. OF EASTERN AVE. PIX BY DERRICK 7-1-2008

42. 3 YEARS AFTER PROJECT COMPLETIONLooking US to DS Photos: Brian StinemanSEPTEMBER 2011

43. 3 YEARS LATER-From DS bend looking US. All stable & fully functional. Great diversity & complexity of vegetation. 3 YEARS LATER-DUCK CR-BRIAN STINEMAN 9-2011

44. 3 YEARS LATER-Looking US in the bite of the bend @ Bendway Weirs & Locked Logs providing hyd. roughness & habitat 3 YEARS LATER-DUCK CR-BRIAN STINEMAN 9-2011

45. 3 YEARS LATER-Looking DS @ a well vegetated bank & overbank riparian corridor. All stable. Bendway Weirs & Locked Logs providing complexity in the channel , 3 YEARS LATER-DUCK CR-BRIAN STINEMAN 9-2011

46. COMBINATIONS OF RESISTIVE & BIOENGINEERING METHODS:CASE STUDY – Elton Creek DS of Freedom 6 Bridge, Cattaraugus County, New York Constructed in 3 days Oct. 2007Longitudinal Peaked Stone Toe Protection {LPSTP} with Joint Planting, Live Siltation & Living Dikes (Shrub Willow transplants)

47. Looking US at eroded bank. Bob is 6 ft 4” (for scale). PRE-PROJECT-Elton Creek DS of Freedom 6 Bridge-derrick-May 17, 2007

48. Elton Creek near Freedom 6 Bridge, Freedom, NY Road Install one-half of the Longitudinal Peaked Stone Toe Protection (LPSTP).

49. BOTTOM LAYER IS JOINT PLANTING & TOP LAYER IS LIVE SILTATION {Willow branches about 1-2 inches in diameter, 6 to 8 ft long, 2/3 in ground, 1/3 out, intermixed with Silky & Red Osier Dogwood that is 4 to 6 ft long}

50. Elton Creek near Freedom 6 Bridge, Freedom, NY Road Install adventitious rooting Willow Poles