|
Project Design: Buck
Engineering
Primary Contractor: Roger
Swanson Construction Company
|
CAMPBELL
(February - April 2001)
|
|
Project
Background
This site is along a 3,900-foot reach of Little Brasstown
Creek immediately upstream of its confluence with Brasstown Creek. The
primary property owner is the John C. Campbell Folk School in Brasstown,
NC.
Little Brasstown Creek flows through a
wide alluvial valley as it nears its confluence with Brasstown Creek.
The lower reach of Little Brasstown Creek lacked an adequate riparian
buffer. Severely eroding stream banks and channel instability indicated
substantial stream degradation. Past channel modifications (channelization)
of the lower reaches of the creek were instrumental in the degradation.
Restoration goals for this project were
to improve water quality and aquatic habitat in Little Brasstown Creek
by reducing bank erosion and sedimentation, improve stream stability and
riparian and floodplain functionality.
The Campbell project is one of the
oldest HRWC stream restoration sites (constructed in winter 2001) and
was the first location where both HRWC and the consultant, Buck
Engineering, attempted a complete “Priority 1” pattern change. The
stream bed consisted almost entirely of sand and construction
contractors were unable to find bedrock on which to seat the majority of
the structures. Because of the much slower, glide/pool nature of the
reach, and the lack of a solid foundation, log structures were
installed, rather than rock structures.
|
(Picture by Buck
Engineering)
Before |
(Picture by Buck
Engineering)
During
|
|
After
|
At various points throughout the
7-year period since construction was completed, mowing of the
walking path and viewing areas (that was allowed in the original
agreement) has been excessive and has encroached on the riparian
buffer. HRWC and the Folk School have replanted buffer
vegetation in these areas and, each time a new maintenance
person gets overly eager, HRWC continue to work with the Folk
School to correct the error.
Following storm events in fall of
2004, HRWC attempted to repair the lowest, most intact log cross vane
structure to no avail and personnel have been routinely checking on the
site ever since. Numerous visits from engineers with Buck Engineering
and others familiar with stream restoration techniques have failed to
result in a solid recommendation for further action.
2008 Status
Approximately 2,200
feet of the Campbell project were monitored in 2005, 2006 and 2007. The
monitored portion of the Campbell stream restoration project is largely
unstable, with several areas of concern. A need for immediate repair
exists, as well as a long-term repair and maintenance strategy to ensure
the success of the project. All 17 structures that were monitored have
experienced some degree of failure, with most currently not providing
any positive functions. The structure failures appear to have
exacerbated localized stream bank erosion, as well as having allowed
downcutting of the channel bed. Between 2005 and 2007, most structures
show little or no change. The restored stream is currently classified as
an E5/C5. The streambed slope is 0.002 feet/foot, with a sinuosity of
1.18. The streambed is characterized by very fine sand.
The restored reach
lacks a well-defined riffle and pool sequence, though longer riffles and
pools developed between 2005 and 2007. The riffles and runs are
composed of a very fine substrate, which does not provide ideal
macroinvertebrate habitat. Stream bank erosion is occurring
sporadically throughout the channel, though increased vegetative growth
is likely limiting erosion.
Despite the failure of most of the
structures, this reach of Little Brasstown Creek is in much better shape
today than prior to restoration.
Planted woody
vegetation, natural woody regeneration, and herbaceous growth are
generally successful and lush on the buffer and banks at the Folk
School. The heavy shade helps to mitigate water temperatures within the
restored reach.
The 2007
macroinvertebrate assessment yielded a bioclassification of Poor,
compared to Fair in 2006 and Good/Fair in 2005. The number of EPT taxa
and EPT taxa abundance dramatically decreased in 2007 from already low
levels in 2005 and 2006. Although significant problems with bank
erosion and high Total Suspended Solids were identified over the 3-year
monitoring period, no change was reported in any other category. The
reason for the declining trend in the macroinvertebrate population at
Campbell between 2005 and 2007 is unknown.
3-Year Study
Recommendations
In
addition to continuing to monitor this reach in subsequent years,
recommended actions include:
-
Continue
negotiations with the Folk School to keep mowing in check
-
Re-stake
some areas of bare bank
-
Remove
invasive patches of kudzu, Japanese honeysuckle, privet, Lespedeza,
and multiflora rose
-
Monitor
for further invasion from upstream of kudzu, privet and Lespedeza
-
Repair
Structure K
-
Evaluate
implications of beaverdams at STA 5+12 and 12+03
|
