20030426 Ver 1_More Info Received_20030709

NETIANDS 1401 GROUP
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NATEAQUALITYSECTION City of Raleigh
Kyle Drive/Beaverdam Creek
Stream Restoration Plan
Addendum 1
Sediment Transport Assessment
The cause of this restoration effort was direct mechanical impacts to the streams and was not due to
systemic watershed alterations. It is not possible to directly know if these impact areas were stable prior to
disturbance. Since the impacts being restored were localized in nature and not from watershed changes, it
was determined that a reference stream reach downstream of each stream impact area would be
appropriate to assess and infer the stability of the impacted streams prior to disturbance. Since these
reference reaches are receiving the same water as the restoration sites, have the same particle sizes and the
restoration design was based on the reference site dimensions; the reference sites were used as a primary
tool in determining the likely stream stability within the restoration areas. During the reference reach
investigation, the reference areas were found to be stable with no appreciable degradation or aggradation.
The stream impact area #1 is experiencing aggradation due to eroding banks from a recently installed road
crossing directly upstream of the restoration area. This aggradation is very localized in stream impact area
#1 and does not persist downstream to reference reach 1. Once the roadside banks are stabilized, it
appears that stream impact area #1 should be as stable as reference reach 1.
Reference reach 2 is directly downstream of stream impact #3. Reference reach 2 is very stable with an
active connection to its floodplain. The sediment passing through stream impact area #3 is the same as
that passing through reference reach 2. However, some undercutting of the unprotected bank in stream
impact area #3 is occurring. The in-stream structures placed within stream impact area #3 will serve to
keep stream pressure off of the bank. This should eliminate any bank instability and should make the
restoration area as stable as reference reach 2.
Since the direct upstream development and any future development will need to comply with the Neuse
Buffer Rules, it is anticipated that future stormwater inputs will be appropriately buffered. The
implementation of buffer protection should ensure the long term stability of the restoration reaches as
well as the reference reaches.
Dewberry
Basic Information for Plan Approval
1. Morphological measurements (see Appendix B) - not all of the measurements are applicable
in every instance.
2. Typical stream cross sections - Typically, a riffle cross section and a pool cross section that
includes the entire flood prone area. The bankfull and flood prove area elevations should be
indicated. Similarly, a riffle cross section of the reference stream(s) should be provided.
3. Plan view - Scaled plans that show the location of the proposed (preferably with stationing)
and the existing stream. In most instances, the bankfull contours and flood prone area
contours, in stream structures, bank revetments/stabilization, channel plugs, planting plan,
vegetation conditions, stormwater outlets, grade controls, bridges, culverts, sewer lines, roads,
fencing, and easement lines should also be provided.
4. Longitudinal Stream Profile - A scaled profile that indicates the thalweg , bankfull, and top of
bank elevations should be provided for the design and reference streams. In many cases it
may also be necessary to show the existing land elevations for the design stream.
5. Planting Plan - A planting and/or vegetation management plan should also be required. The
plan should indicate the extent, density, and species of plants to be provided.
6. In stream structure, bank revetment/stabilization, and stormwater outlet typicals - Detailed,
typical plans should be provided for all in stream structures, bank revetments or stabilization,
and stormwater outlets. The typicals should include materials and specifications as well as
relative lengths, positions, and angles.
7. Sediment transport analysis - A sediment transport analysis should be provided based on the
current, relevant, accepted practices. The sediment transport analysis should be relevant to
the stream bed load type and should predict bed load transport equilibrium.

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