20150954 Ver 1_More Info Received_20151118

Steve Troxler North Carolina Department of Agriculture
Commissioner and Consumer Services
Division of Soil and Water Conservation
Date: November 16, 2015
To: Karen Higgins
401 & Buffer Permitting Unit Supervisor
Division of Water Resources
Department of Environmental Quality
From: Daphne Cartner, EI C,
RE: WPCC Hunting Creek Bank Stabilization
Project #15 -0954
Patricia K. Harris
Director
Please find enclosed three copies of the information requested by Mr. Ed Williams of the Asheville
Regional Office in a letter dated October 14, 2015.
Your first concern is the verifying that the rock size would be sufficient not to scour. Attached is a
calculation sheet indicating the minimum size rock based on shear stress for the stream. This calculation
indicates a rock size of 15.9 cu -ft. We specified an average rock of 24 cu -ft. for the Rock Structures and
toe material.
Your second concern was the proposed dimensions. We took a cross - section of a stable riffle just
upstream of the work area to match as this is not a restoration project. The cross - sectional area in that
riffle is 67 sq -ft (note the attached Regional Curve for a 7.42 sq. mile drainage area is 70.4 sq -ft). The
bankfull width of the riffle is 23.5 ft. and the mean depth is 2.8 -ft. The stabilization project is primarily
in a pool section and therefore these dimensions are slightly higher in the repair cross - section. Please note
that though width and depth dimensions are plotted against drainage area that this data is from a variety of
stream types and often does not correlate with actual dimensions of other stream types.
If you have additional questions concerning the design or if you don't feel this fully addresses your
concerns, please feel free to contact me directly.
MAILING ADDRESS
Western Peidmont Tech Services Office
Division of Soil and Water Conservation
PO Box 845
Mocksville, NC 27028
Telephone: 336 - 753-0076
An Equal Opportunity Employer
LOCATION
Long Building Suite B
314 W Water Street
Mocksville, NC 27028

WPCC Hunting Creek Streambank Stabilization
Rock Size Calculation
Bankfull Shear Stress Calculation:
Hydraulic Radius (ft) 2.60
Slope (ft/ft) 0.003
T = (lbs/ft2) 0.44
y = 0.5656Ln(x) + 2.98
Min. Rock Size = (ft) 2.517
Min. Rock Vol. (fe) 15.952
Min. Rock Weight 1754.705
(assume 1101bs/ft3)

CONSTRUCTION SPECIFICATION
ROCK STRUCTURES
The work shall consist of the construction of natural rock or rock riprap structures
including rock vanes, J -hook vanes, rock cross vanes, cross vane rock weirs, and/or
step -pool structures. The work shall consist of furnishing, transporting and installing
materials to construct the rock structures in accordance with the plans and
specifications.
Materials
Individual rocks shall be dense, sound and free from cracks, seams, and other
defects. The rocks shall have a specific gravity of not less than 2.5. The size and
grading of the rock shall be as shown on the drawings. The dimensions of the rock
shall be 4 ft long x 3 ft. wide z 2 ft. high. The dimensions may vary within +/ -1 foot.
Flat rocks are preferred since they are more adapted for the intended use. The
weight range of each rock should be between 1 and 3 tons. The source of rock
shall be identified and approved by the Engineer prior to delivery to the site. It is
anticipated that the rock will be a special order to obtain the specified sizes if the
rock is to be obtained from a quarry.
Subarade Preparation
The subgrade surfaces on which the rock is to be placed shall be cut or filled and
graded to the lines and grades shown on the drawings. When fill is required, it shall
consist of approved materials that have been placed according to the Construction
Specification for Earthfill. The rock shall not be placed until the prepared subgrade
has been inspected and approved by the Engineer.
Placement
The rock shall be placed by equipment on the surfaces and to the depths specified.
The footer rock shall be placed first If more than one footer rock layer is to be
placed, placement shall begin with the bottom layer and proceed in sequence until
all footer rock layers and the surface rock layer have been placed. A hydraulic
excavator equipped with a hydraulic thumb shall accomplish placement of the rock
in the structure unless othervAse approved by the Engineer.
The rock shall be placed in a manner to prevent damage to structures. Hand
placing will be required to the extent necessary to prevent damage to any structure.
All rock structures are designed to be installed on a 20 degree angle from the
channel bank toward the center of the stream. The grade, top and bottom, of the
structure gradually tapers down from the channel bank toward the center of the
stream. For the structure to work properly, the rock must be placed as shown on
the drawings unless directed otherwise by the Engineer.
NRC3 -NC Page 1 of 1 2/99
Rock Structures AWessup

SPECIFICATIONS FOR CONSTRUCTION
FOR
WPCC HUNTING CREEK BANK STABILIZATION
BURKE COUNTY, NORTH CAROLINA
FILL MATERIALS AND PLACEMENT: The material placed in the fill shall be free of sod, roots, frozen
soil, stones more than six (6) inches in diameter (except for rock fills), and other objectionable material.
The foundation area shall be roughly shaped and compacted before the placement of any fill material.
The contact surface shall be thoroughly scarified and moisture added as needed so that the first layer of
fill material will be properly bonded to the foundation when compacted. The placing and spreading of fill
materials shall be started at the lowest point of the foundation and the fill brought up in horizontal layers
not to exceed eight (8) inches in thickness prior to compaction. The slope between the existing ground
and fill to be placed shall not be steeper than 3 horizontal to 1 vertical. The bonding surface shall be
treated the same as that specified for the foundation so as to insure a good bond with the new fill. The
moisture content of the fill material shall be adequate for obtaining the required compaction. Material that
is too wet shall be dried to meet the requirements, and material that is too dry shall have water added and
be mixed until the requirement is met it is generally preferred to use material slightly wetter than
optimum than dryer than optimum. Construction equipment shall be operated over all areas of each layer
of fill to insure that the required compaction is obtained. A sheeps -foot roller or a mechanical roller -
compactor shall be used as needed to obtain the required compaction. Fill adjacent pipe conduits shall
be carefully compacted to a density equivalent to that of the surrounding fill by manually directed power
tampers or plate vibrators. Fill materials compacted with manually directed power tampers or plate
vibrators shall be placed in horizontal layers not to exceed four (4) inches in thickness prior to
compaction.

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RIVERMORPH CROSS SECTION SUMMARY
River Name: Hunting Creek
Reach Name: Reach 1
Cross Section Name: Riffle?
Survey Date: 11/12/2015
Cross Section
Data Entry
Left
BM Elevation:
Floodprone Elevation (ft)
0 ft
Backsight Rod
Reading:
0 ft
TAPE
FS
ELEV NOTE
-------------------------------------------------
0
0
1062.18
11.66
0
1061.09
15.25
0
1061.24
24.31
0
1061.68
33.85
0
1060.87
37.27
0
1060.71
43.87
0
1058.51
47.07
0
1057.56
47.69
0
1057.26 BKF
48.23
0
1056.93
54.03
0
1053.89
59.34
0
1052.99
62.91
0
1053.39
67.06
0
1054.04
67.94
0
1055.12
68.69
0
1055.34
77.05
0
1061.84
77.96
0
1062.57
78.07
0
1062.55
84.65
0
1061.87
90.77
0
1062.38
97.94
0
1063.23
----------------------------------------------------------------------
Cross Sectional Geometry
---------------------------------------------------------------- - - - - --
----------------------------------------------------------------------
Entrainment calculations
---------------------------------------------------------------- - - - - --
Entrainment Formula: Rosgen.Modified shields curve
channel
Left
Right
Floodprone Elevation (ft)
1061.53
1061.53
1061.53
Bankfull Elevation (ft)
1057.26
1057.26
1057.26
Floodprone width (ft)
64.84
Bankfull width (ft)
23.47
11.73
11.74
Entrenchment Ratio
2.76
-
Mean Depth (ft)
2.84
2.68
2.99
Maximum Depth (ft)
4.27
4.27
4.26
width /Depth Ratio
8.26
4.38
3.93
Bankfull Area (sq ft)
66.6
31.44
35.15
wetted Perimeter (ft)
25.66
16.91
17.28
Hydraulic Radius (ft)
2.6
1.86
2.03
Begin BKF Station
47.69
47.69
59.42
End BKF Station
71.16
59.42
71.16
----------------------------------------------------------------------
Entrainment calculations
---------------------------------------------------------------- - - - - --
Entrainment Formula: Rosgen.Modified shields curve

�. Channel Left side Right side
sl ope�.�' 0 0 0
shear stress ;.(lb /sq ft)
Movabl'e",'Parti tl a (mm)
J• -