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PROGRAM
November 17, 2010
Todd Tugwell
Regulatory Division-Wilmington District
U.S. Army Corps of Engineers
11405 Falls of Neuse Road
Wake Forest, NC 27587
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Re: Elk Shoals Stream Restoration Project-Additional Information Summary and Repair Recommendation
Dear Mr. Tugwell,
The purpose of this letter is to provide a repair recommendation to the Interagency Review Team (IRT), regarding the Elk
Shoals stream restoration project. On May 25, 2010, EEP conducted a closeout visit to Elk Shoals. During the May visit
two primary issues came up, one, a small headcut on one of the tributaries and two, stability issues involving a 900 linear
foot portion of the channel that involved putting the flow back into a remnant channel (from station 20+00 to station
29+00). The stability issues on the remnant channel involved primarily two meander bends (one at station 22+00, and
another at station 24+30) and some scour issues downstream of station 25+00 to station 28+50.
Summary Information
June 21, 2010 -Stream Mechanics Letter
Restoration Systems asked Will Harman to provide comments to the questions raised at the closeout visit. During a June
16th site visit Mr. Harman addressed the stability issues and in his June 21St letter (attached) came up with the following
recommendations:
1. No signs of system wide instability in the remnant channel, vertical or lateral,
2. No risk of localized bank erosion in the remnant channel will threaten downstream or upstream project
reaches,
3. Bank erosion (meander bend) at station 22+00 should be repaired and woody debris removed,
4. Headcut in UT 1 must be repaired,
5. Removing large woody debris from straight section of remnant channel is optional, and
6. Removal of beaver dam is optional.
August 30, 2010- Baker Letter
A meeting was held at EEP on July 30, 2010 with Restoration Systems personnel, Baker personnel, and Will Harman
(Stream Mechanics) to discuss the status of the Elk Shoals project and whether any further information would be needed
before a recommendation was submitted to the IRT. EEP wanted to see more information regarding vertical stability and
floodplain access in the remnant channel area. Members of Baker visited the site on August 4, 2010 and produced a letter
(attached) to Restoration Systems on August 30, 2010. Additional cross sections were performed in the remnant channel
area to determine, 1) if the incision at cross section #3 had increased or decreased, 2) if the incision was present upstream
or downstream of the cross section and finally, 3) to evaluate what degree the remnant channel section had access to its
adjacent floodplain. The additional surveys indicated that the cross sectional areas were consistent with regional curve and
design criteria cross section area as mentioned in the Restoration Plan, and therefore, this section of the remnant channel
does have access to its floodplain. In addition, Baker's analysis of the channel upstream and downstream of cross section
#3 confirmed that the channel did not demonstrate instability but rather, "natural changes in bed features that occur on all
streams over time".
EEP staff site visit to Elk Shoals- November 9, 2010
On November 9t', EEP staff (Tim Baumgartner and myself) conducted a site visit to provide a final verification that the
additional surveys showed attachment to the floodplain and finalize plans for a repair recommendation. Starting at station
20+00 we walked the 900 linear foot remnant channel section under concern by the IRT.
At station 20+00 Photo 1 shows Tim in a riffle area where bankfull is at his shoulder height and evidence of wrack is
visible on the floodplain.
Photo 2 is of the meander at station 21+00, while exhibiting a tight radius of curvature, the bend does not show excessive
erosion and the mature vegetation present is doing a good job of holding the bend in place, no repair is recommended and
none was recommended on the closeout site visit.
Photo 3 shows the meander bend at station 22+00 where the IRT recommended a repair. EEP concurs with this
recommendation.
Photo 4 is downstream of the aforementioned meander bend at station 22+60, right at cross section #3. Bankfull was at
Tim's head level and further evidence was noted of wrack on the floodplain.
Photo 5 and 6 is looking upstream and downstream, respectively at the meander bend at station 24+30. During the
closeout visit, IRT personnel also recommended that a repair was needed at this location. After further review of
additional data gathered by Baker and observations made on site by Will Harman, EEP believes this meander bend to be
stable and provide excellent habitat for fish with the old rootwads now primarily serving as cover logs. While some scour
has occurred at this bend, the mature vegetation present with the existing habitat supports our decision not to intervene at
this location. Beaver were noted on site at this most recent visit. Evidence of backwater begins to occur at this area
(station 24+00). Therefore, observation of scour downstream of station 24+30 was not possible because of the backwater
effect. Moreover, during the closeout visit, IRT members pointed out the scour downstream of this meander bend as
further evidence of instability. At the time of the closeout visit, and now, EEP staff believe the scour identified was
primarily a result of beaver downstream and then subsequent removal exposing portions of bank which were inundated for
a period of time.
It is important to note, that the methods utilized by Restoration Systems (RS) and Baker during design and construction of
the remnant channel reach is conducive to the restoration approach that the IRT is currently encouraging. RS and Baker
used the "light touch" methodology in this instance which yielded largely successful results, yet does not give the
manicured appearance as portions totally redesigned and constructed.
In summary based on the contributions/observations made by Will Harman and Baker's analysis resulting from the extra
surveyed cross sections EEP recommends the repair of the small headcut on Tributary 1 and of the meander bend at
station 22+00 are the necessary actions needed to finalize closeout for this project. EEP staff do not believe repairs are
necessary for meander bend located at station 24+30, nor do staff believe a whole scale intervention of regrading of a new
floodplain is warranted for this section of the remnant channel.
If there is any further information you request, please let me know.
Sincerely,
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Mac Haupt
Monitoring Supervisor
CC: Worth Creech, Restoration Systems
Photo 1. Tim near station 20+00, top of bank at his shoulder height, presence of recent wrack was visible on the
floodplain.
visit.
Photo 2. Meander bend at station 21+00. No repair recommended and IRT did not recommend repair at closeout site
Photo 3. Meander bend at station 22+00. Repair recommended.
Photo 4. Tim at cross section #3 (approximately station 22+50). Top of bank roughly at Tim's head level.
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Photo 6. Looking downstreaxn of station 24+30.
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