20180353 Ver 1_More Info Requested_20180416

Johnson, Alan
From:Belflower, Jeff - NRCS, Spindale, NC <[e-mail]>
Sent:Monday, April 16, 2018 11:31 AM
To:[e-mail]; Johnson, Alan
Cc:Glenn, Jabioas - NRCS, Statesville, NC; Propst, Jim - NRCS, Statesville, NC
Subject:\[External\] Miller revised PCN
Attachments:StephenMiller_PCN_Revised4-16-18.pdf
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Cathy and Alan,

A revised PCN is attached. I have included my responses to Cathy’s remarks 1) and 4) below for clarity. You will see 20’
of ford-type crossing shown in the impact table. I reduced that number from the 30’ we discussed during the site visit in
order to reduce the amount of permanent impacts. I will give Mr. Miller the option to either install two 10’ wide crossings
at the locations shown in the design, or to install one wider crossing (15’ to 18’ wide) at one of the proposed locations.

Section B, 3e:
This stream channel stabilization project will address instabilities along this approximately 1,270 foot long reach. The
channel has migrated laterally in multiple meander bends, likely due to straightening and channelization in the past, an
overly wide channel, and a high width/depth ratio. This process is continuing to erode vertical mass wasting banks on the
outside of almost every meander bend. Minor instabilities and an over widened channel exist throughout the reach. The
objective of this design is to address the stream’s dimension, pattern, and profile to improve sediment transport and stop
bank erosion. Pattern or alignment will be corrected to a tolerable range and held in place with multiple structures
including log-vanes, cross-vanes, and j-hooks. These structures will also maintain a stable channel dimension and profile
created through construction activities. Improved aquatic and terrestrial habitat will be a by-product of the channel
stabilization. Native herbaceous and woody vegetation will be installed to provide long term stability.

Construction will involve the use of an excavator with a hydraulic thumb to place rocks and logs and to excavate new
benches and channel. Work will begin at the upper end of the reach, and will progress downstream. Construction will only
occur during base-flow or low flow conditions, and will progress in stages. Each stage will be seeded, mulched, and
matted before the next rain event. The excavator will work from top of bank; disturbance of the channel bed will be
minimal. A bulldozer will be used primarily to smooth disturbed areas above top of bank at the end of the project.

Section D, 1a:
Stream loss was minimized during the design process. The proposed stream length is mainly a function of designed
meander lengths and radius of curvature. The NRCS Area 1 engineering staff designs based on ratios derived from
reference reach data and successful projects. The designed radius of curvatures and meander lengths fall within our
acceptable range of ratios. The decrease in stream length is due to the prevalence of excessively sharp meanders
throughout the existing channel (radius of curvature is too small). Every effort was made to design a natural pattern with
appropriate sinuosity and meanders throughout the proposed reach.

Thank you both for your help and guidance. Please let me know if I can do anything else to improve this application.

Jeff Belflower, PE
Civil Engineer
USDA-NRCS
500 West St
Spindale, NC 28160
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828-287-4220, Ext. 110

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