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Analysis of Environmental Shifts Over 6.5 Years in Hickahala Creek Pipeline Project

Study reveals changes in Hickahala Creek due to pipeline construction, including bank erosion, stone displacement, and flow direction alterations. Detailed analysis by Dr. Chester Watson and highlighted concerns are portrayed.

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Analysis of Environmental Shifts Over 6.5 Years in Hickahala Creek Pipeline Project

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  1. Headcut gets taller & ACM mat flips out of the upstream key trench of the downstream pipe crossing, which causes problems.Project is 6.5 years old.

  2. Looking DS @ newly exposed river weights show that since March 2009 another 8 inch headcut has moved upstream to the ACM. 6.5 YEARS LATER-HICKAHALA CR. @ PIPELINE. PIX-DERRICK 3-31-2010

  3. Analysis by Dr. Chester Watson of stage data from the gage on the first bridge downstream of the pipeline crossing shows that the gage has dropped an average of 0.2 ft/per year for the last 15 years, which translates into the 3 ft of headcut observed at the downstream end of the ACM at the pipeline crossing.

  4. Looking @ ACM that has flipped out of its US key on the downstream pipe crossing. 6.5 YEARS LATER-HICKAHALA CR. @ PIPELINE. PIX-DERRICK 3-31-2010

  5. Looking US. Bank erosion US of the tree is a concern if it breaks thru the clay outcrop. Bank pins will be installed to ascertain rate of bank erosion. However, erosion on this bank appears less severe now than April 1, 2004. Bank erosion Clay outcrop Next picture 6.5 YEARS LATER-HICKAHALA CR. @ PIPELINE. PIX-DERRICK 3-31-2010

  6. It appears that stone is missing, but in reality there is up to 2.5 ft of sediment over the top of the existing stone on the right bank of Thompson Creek. 6.5 YEARS LATER-HICKAHALA CR. @ PIPELINE. PIX-DERRICK 3-31-2010

  7. Looking US @ stone that has launched as designed. Veg growing in the LPSTP highlights long-term stability. However, when more LPSTP launched upstream compared to downstream, the resulting curve (shown) is guiding water toward the left bank 6.5 YEARS LATER-HICKAHALA CR. @ PIPELINE. PIX-DERRICK 3-31-2010

  8. Looking US. Flow is deflecting off of the left bank (white arrow & exposed LPSTP) & heading toward the right side of the DS pipe crossing (black arrow). 6.5 YEARS LATER-HICKAHALA CR. @ PIPELINE. PIX-DERRICK 3-31-2010

  9. Looking US @ ACM that has flipped out of its US key. 6.5 YEARS LATER-HICKAHALA CR. @ PIPELINE. PIX-DERRICK 3-31-2010

  10. The survey shows that water is flowing under the pipe at the arrow. This means the pipe is suspended in flow & in trouble 6.5 YEARS LATER-HICKAHALA CR. @ PIPELINE. PIX-DERRICK 3-31-2010

  11. It’s a rental!! Pix by Derrick March 18, 2009

  12. AT-GRADE GRADE CONTROL STRUCTURE ON HICKAHALLA CREEK NEAR SENATOBIA, MS. (upstream of the pipeline crossing) Mini case study: 1 of 12

  13. AT-GRADE GRADE CONTROL, FLAT SLOPED SAND BED STREAM Crest of stone equal to invert of stream Sheet pile Headcut advancing Stone has adjusted and arrested the advancing headcut Cover over Stone has adjusted Mini case study: 2 of 12

  14. AT-GRADE GRADE CONTROL, SAND BED STREAM Crest of stone equal to invert of stream Sheet pile cutoff wall Headcut advancing Stone has adjusted & arrested the advancing headcut Cover over Stone has adjusted Mini case study: 3 of 12

  15. At-grade, grade control structure, Hickahala Creek, MS, {rural, sand bed, slope<1%, pool-riffle-pool, straightened, incised} as-built in 1989, note concrete cap on sheet-pile cutoff wall Mini case study: 4 of 12

  16. At-grade, grade control structure, Hickahala Creek, MS, as-built in 1989, note concrete cap on sheet-pile cutoff wall Mini case study: 5 of 12

  17. Sheet-pile cutoff wall Mini case study: 6 of 12 At-grade grade control, Hickahala Creek, MS. Functioning as designed (to arrest headward migration of knickpoints) picture taken April 2004

  18. Mini case study: 7 of 12 Hickahala at-grade GC at high flow, April 6, 2005

  19. Sheet-pile cutoff wall Mini case study: 8 of 12 At-grade GC, Hickahala Creek, MS. April 2007. Compared to the 2004 pictures, some stone has been displaced on the DS side of the sheetpile cap.

  20. Sheet-pile cutoff wall Mini case study: 9 of 12 At-grade GC, Hickahala Creek, MS. April 2007. Close-up of displaced stone on the DS side of sheetpile cap.

  21. Sheet-pile cutoff wall Mini case study: 10 of 12 At-grade GC, Hickahala Creek, MS. April 2007. Stone on DS face has self-adjusted to form a pool-riffle-pool configuration.

  22. Sheet-pile cutoff wall Mini case study: 11 of 12 At-grade GC, Hickahala Cr. Except for some movement of stone on the DS side of the cutoff wall, there is little difference between the April 2007 & April 2010 pix.

  23. Sheet-pile cutoff wall Mini case study: 12 of 12 At-grade GC, Hickahala Creek, MS. April 2010. Structure is similar to April 2007. Left bank erosion has increased, right bank is stable.

  24. AT-GRADE GRADE CONTROL, FLAT SLOPED SAND BED STREAM Crest of stone equal to invert of stream Sheet pile Headcut advancing Stone has adjusted and arrested the advancing headcut Cover over Stone has adjusted

  25. AT-GRADE GRADE CONTROL, SAND BED STREAM Crest of stone equal to invert of stream Sheet pile cutoff wall Headcut advancing Stone has adjusted & arrested the advancing headcut Cover over Stone has adjusted

  26. At-grade, grade control structure, Hickahala Creek, MS, {rural, sand bed, slope<1%, pool-riffle-pool, straightened, incised} as-built in 1989, note concrete cap on sheet-pile cutoff wall Mini case study: 1 of 7

  27. At-grade, grade control structure, Hickahala Creek, MS, as-built in 1989, note concrete cap on sheet-pile cutoff wall Mini case study: 2 of 7

  28. Sheet-pile cutoff wall Mini case study: 3 of 7 At-grade grade control, Hickahala Creek, MS. Functioning as designed (to arrest headward migration of knickpoints) picture taken April 2004

  29. Mini case study: 4 of 7 Hickahala at-grade GC at high flow, April 6, 2005

  30. Sheet-pile cutoff wall Mini case study: 5 of 7 At-grade GC, Hickahala Creek, MS. April 2007. Compared to the 2004 pictures, some stone has been displaced on the DS side of the sheetpile cap.

  31. Sheet-pile cutoff wall Mini case study: 6 of 7 At-grade GC, Hickahala Creek, MS. April 2007. Close-up of displaced stone on the DS side of sheetpile cap.

  32. Sheet-pile cutoff wall Mini case study: 6 of 7 At-grade GC, Hickahala Creek, MS. April 2007. Stone on DS face has self-adjusted to form a pool-riffle-pool configuration.

  33. Sheet-pile cutoff wall Mini case study: 6 of 7 At-grade GC, Hickahala Cr. Except for some movement of stone on the DS side of the cutoff wall, there is little difference between the April 2007 & April 2010 pix.

  34. Sheet-pile cutoff wall Mini case study: 6 of 7 At-grade GC, Hickahala Creek, MS. April 2010. ERR is similar to April 2007. Left bank erosion has increased, right bank is stable.

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