20071647 Ver 1_More Info Received_20080104

WNZ
Wetland and Natural Resource
Consultants, Inc.
January 2, 2008
To: N.C. Division of Water Quality
Surface Water Protection Section
Attn: Mr. Kevin Barnett
2090 US Hwy 70
Swannanoa, NC 28778
Re: DWQ Request for More Information
Hard Rock Mine, Cherokee County
DWQ Project # 07-1647
Dear Ms. Karoly / Mr. Barnett,
N.C. Division of Water Quality
401 Wetlands Unit
Attn: Ms. Cyndi Karoly
2321 Crabtree Blvd., Suite 250
Raleigh, NC 27604
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Enclosed is the additional information that your office requested in a letter dated
December 1, 2007. An agency meeting was conducted on August 6, 2007 at the DWQ
Swannanoa office. Agencies present at the meeting included the Corps (Lori Beckwith),
DWQ (Kevin Barnett, Roger Edwards, DWQ counsel), FWS (Bryan Tompkins), and NC
WRC (Dave McHenry).
WNR understood during that meeting that the Corps, Lori Beckwith, had determined
that she was not going to consider the relocated channel in the mine area as an impact.
This channel had been relocated back in the 1960's when the original mine was
operational. Mr. Glen Frank had maintained the existing flow in this channel by
excavating out areas along the channel where flow was being impeded by sediment or
debris but he had not relocated the channel to its current position.
The current relocated channel is 60 to 70 feet upslope (maybe higher in some
locations) of the original stream that existed prior to 1960. The original mining
operation could not have existed without the channel relocation due to the fact that the
old mine rock face is located where the stream used to flow. The area below the mine
pit was altered significantly as well during the old operation. There are old roads and
borrow areas. There is evidence of old gravel piles where the channel was relocated
below the mine area.
Canton Office
PO Box 882
Canton, NC 28716
828-648-8801
828-648-8802 Fax

Since the Corps was not going to consider the mine area as an impact, DWQ requested
that a NW 27 be submitted in order to get approval to restore this channel as soon as
possible. During the meeting it was discussed that an after-the-fact IP would be
submitted for the impacts that have taken place for the development of Wilderness
Creek Falls. WNR has been waiting on a few letters and reports to be completed from
Mr. Frank before submitting the IP. WNR should have the last report early next week
(dam safety report completed by Dan Marks) and should have the IP submitted by the
end of the week.
The following comments should address the additional information requested:
1. "lack of practical alternatives" - Mr. Frank originally looked in to having gravel
trucked to his development by another company and determined that the costs were
going to exceed his financial capabilities due to the long hauling distances. Only then
did he begin looking into the possibility of using the existing mine off Hwy 64. The
mining operation completed by Mr. Frank took place where the existing mine was
located in the 1960's because there was already a road into the area and because there
were large boulders piled up from the existing operation that could be used to crush for
gravel. Mr. Frank thought that he had found a way to gravel his development roads
cheaper and assumed that he was following all applicable rules and regulations.
The costs to operate the existing mine were much cheaper than opening a new area to
mine. Mr. Frank only agreed to open a new area on the property to mine because he
was told during the meeting that he would have to restore the channel immediately. It
is not possible to restore the channel and continue to operate the existing mine due to
space constraints. Mr. Frank was not aware that there was an additional potential mine
on the property until he got the NOV and began asking WNR if he was going to be able
to continue to operate in the existing mine. WNR suggested to him to look elsewhere
on the property for a mine in case he had to abandon the original mine. This is going
to cost Mr. Frank additional monies to open a new mine and is going to create more
overall disturbance than continuing to expand the existing mine.
The only impacts requested in the NW 27 application include the restoration of the
relocated channel above the original mine. DWQ requested that this work be done as
soon as possible and the Corps did not consider this work an impact and did not want
this restoration included in the IP application. The IP application includes the impacts
that have taken place for the development Wilderness Creek Falls. Mr. Frank could
develop Wilderness Creek Falls without restoring the stream which would eliminate
impacts proposed in the NW 27 but he realizes that the channel is unstable and is
contributing sediment downstream. If the relocated channel was to remain in place the
bed and banks would need to be stabilized. Mr. Frank is being asked by DWQ to
Canton Office 2
PO Box 882
Canton, NC 28716
828-648-8801
828-648-8802 Fax

restore a stream that he didn't originally relocate without getting any restoration credit
for doing so, granted Mr. Frank did do some maintenance on the relocated channel.
2-4. 'site plan", 'overall description", and ~~stormwater" - WNR has provided plans and
details for the stream restoration project. As earlier stated the NW 27 application was
requested by DWQ and an IP for the development will be submitted by the end of next
week. The Corps is not considering the stream restoration project (being proposed) an
impact. Full site plans and a project description for the Wilderness Creek Falls
development will be provided in the IP application as well as proposed building site
details (if any lots have potential stream or wetland impacts), a delineation map, and a
land use description.
A stormwater management plan will be included for the development in the IP
application. The proposed activities under NW 27 should benefit stormwater treatment
with the establishment of the 30' (60' total) adjacent buffers along the restoration
corridor. The restoration will also eliminate the existing sedimentation that is occurring
during storm events due to the bare nearly vertical banks of the relocated channel.
5. "stream restoration plan" -
Existing Site Conditions.
The existing stream is highly unstable and highly erosive as can be seen in the photos
in the restoration plan. The stream was diverted into a ditch on the side slope of the
valley. Due to this ditching, the altered stream exhibits morphological parameters that
are not fitting of an ASa+ stream especially with regards to dimension. The dimension
of the ditch/new channel shows a stream that is not entrenched. This is because when
the channel was diverted, no thought was placed into designing the proper cross
sectional area.
The existing ditch does not have the capacity to hold its water at bankfull as shown in
the cross sections and will result in water flowing down the side of the valley wall
causing more erosion. The existing ditch shows the characteristics of an A5a+ channel
based on the steep slope of the channel (13%), the relatively low sinuosity (1.1), and
the current valley type. This was the basis of determining the stream to be an A
stream.
Reference Reach.
The reference reach data is included with the restoration plan dated 9/11/07. The
reference reach data has been submitted and can be found in Attachment C of the plan.
Restoration Plan.
"Original form" was intended to mean place of origin or relocating and restoring the
stream back to where the channel was historically at the bottom of the valley. If left
alone, the current channel will continue to cause erosion and may eventually slide down
Canton Office 3
PO Box 882
Canton, NC 28716
828-648-8801
828-648-8802 Fax

the valley wall unless it is stabilized in place. To avoid continued erosion and impact to
downstream water quality the best location for the creek is at the bottom of the valley
in the altered geomorphic site.
Construction Plan and Specifications.
There are currently two distinct drops. Both are abrupt, bedrock faces. The third
~~drop" is more of a sloped bedrock slide.
Rock Vanes.
The designed reach drops from an elevation of 2,021 feet to 1,894 feet in just under
875 feet. In order to hold this steep grade, cross vanes will have to be utilized. Cross
vanes will be installed to mimic reference reach conditions which consisted of step pool
features. Without structures, there would be no habitat complexity. Reference reach
data shows these key habitat features such as riffles, runs, and pools.
Restoration Overview.
Attached is a restoration overview with a new key showing the color coded channel.
Also, see detailed plan view at a scale of 1:20 showing stations, structures, habitat
features, and topo. (See Restoration Plan dated 9/11/07).
Proposed Plan View.
The design was based off of field data collected from an existing stable A4a+ stream in
the same watershed (see attachment C of the restoration plan). A reference reach
having a similar watershed size, slope, valley type, and stream type was located on site.
The reference reach profile shows a slope of 19%. It also shows that the reach is
steeper in some sections than others. The majority of the slope is from station 0+81 to
1+12. The slope in this section is 61%. The lower portion of this reach from station
2+15 to 3+00 has a slope of 6%. In this particular instance the reference reach is
meant to be used as a guide or template to emulate stable dimension, pattern, and
profile. The submitted design emulates a stable A4a+ stream with varying degrees of
slope throughout the entire 300 foot reference reach. Changing or splitting the
reference reach into another Rosgen stream type would not change the dimension or
pattern of the design; however it would change profile. The profile of the stream was
designed to meet the change in slope. Steeper sections required more grade control,
while sections with less gradient were given longer riffle features.
Cross Vane Typical.
Pavement and subpavement samples were collected at the reference reach and the
existing channel above the diversion in order to estimate shear stress at bankfull.
Bankfull shear stress at the reference reach was 7.05 Ib/ft^2. Using Shield's Curve we
can see that in a bankfull event the shear stress of 7.05 Ib/ft^2 would move any
particle less than 500mm. The existing channel showed similar results. Bankfull shear
stress was 5.17 Ib/ft^2. Shield's Curve reveals that at bankfull the shear stress of
Canton Office 4
PO Box 882
Canton, NC 28716
828-648-8801
828-648-8802 Fax

5.171b/ft^2 can move any particle less than 500mm. The results will guide us in
determining rock size. Only rocks with an intermediate axis greater than 1.5 feet will
be used for structures.
The design has been completed to work with the existing disturbed topography. If
DWQ, NC WRC, or the Corps have additional concerns about the restoration plan, we
would suggest a meeting to discuss other viable alternatives.
Best Regards,
~~s ~~ ` ~~
Kevin Mitchell and Jennifer Robertson
Copies To:
Corps -Lori Beckwith
NC WRC -Dave McHenry
Canton Office 5
PO Box 882
Canton, NC 28716
828-648-8801
828-648-8802 Fax

ENTRAINMENT CALCULATION FORM
Stream: Wilderness Creek Falls Existin Reach: Existin Channel
Team: WNR Date: 8.23.07
Information Input Area
3.6 Dso Riffle bed material D50 (mm) Pavement
2.5 D~50 Bar sample D50 (mm) Sub-pavement
100 D; Largest particle from bar sample (mm) 0.33 (feet) mm/foot
0.145 Se Existing bankfull water surface slope (ft/ft)
0.84 de Existing bankfull mean depth (ft)
8.3 Wbkf Existing or Design Bankfull Width
9.98 P Wetted Perimeter of Riffle Cross Section ft
5.7 A Area of Riffle Cross Section ft)
0.57 R H draulic Radius of Riffle Cross Section ft)
1.65 gs Submerged specific weight of sediment

Calculation of Critical Dimensionless Shear Stress
1.44 Dso/D so If value is between 3-7 Equation 1: t*~; = 0.0834(Dso~ so)-osn
27.78 D /D If value is between 1.3-3.0 E uation 2: t' - 0.0384(D /D )-0887
so q ~~ - ~ so
0.0000 t~~; Critical Dimensionless Shear Stress Equation used: 1
0.0020 t ~; Critical Dimensionless Shear Stress Equation used: 2
Cal culation of Bankfull Mean Depth Required for Entrainment of Largest Particle in Bar Sample

0.01 d~ Required bankfull mean depth (ft) d~ = t~_D;
Se

0.84 de Existing bankfull mean depth (ft)

Calculation of BKF Water Surface Slope Required for Entrainment of Largest Particle in Bar Sample

0.0013 ST Required bkf water surface slope Sr = t~D;
de

0.1450 Se Existing bkf water surface slope

Sediment Transport Validation
5.17 Bankfull Shear Stress t~ =gRS (lb/ft2) where Density of water = g = 62.4 lbs/ft3
500 Moveable particle size (mm) at bankfull shear stress (predicted by Shields Diagram)
1.0 Predicted shear stress required to initiate movement of D; (mm) (see Shields Diagram)
Note: Particles lar er than the moveable article size at bankfull shear stress ma be mobilized.

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ENTRAINMENT CALCULATION FORM
Stream: Wilderness Creek Falls Reference Reach: Reference Reach
Team: WNR Date: 8.23.07
Information Input Area
20 D50 Riffle bed material D50 (mm) Pavement
4.1 D~50 Bar sample D50 (mm) Sub-pavement
93 D; Largest particle from bar sample (mm) 0.30 (feet) mm/foot
0.19 Se Existing bankfull water surface slope (ft/ft)
0.68 de Existing bankfull mean depth (ft)
9.4 Wbkf Existing or Design Bankfull Width
10.76 P Wetted Perimeter of Riffle Cross Section (ft)
6.4 A Area of Riffle Cross Section ft)
0.59 R H draulic Radius of Riffle Cross Section ft)
1.65 gs Submerged specific weight of sediment

Calculation of Critical Dimensionless Shear Stress
4.88 D50/D s° If value is between 3-7 Equation 1: t{~; = 0.0834(D50/D 50)'0'872
4.63 D /D If value is between 1.3-3.0 E uation 2: t* - 0.0384(D /D ° 887
~ 50 q ci i 50)
0.0209 t~~; Critical Dimensionless Shear Stress Equation used: 1
0.0000 t ~; Critical Dimensionless Shear Stress Equation used: 2
Cal culation of Bankfull Mean Depth Required for Entrainment of Largest Particle in Bar Sample

0.06 dr Required bankfull mean depth (ft) dr = t g D;
Se

0.68 de Existing bankfull mean depth (ft)

Calculation of BKF Water Surface Slope Required for Entrainment of Largest Particle in Bar Sample

0.0154 S~ Required bkf water surface slope S~ = t~_D;
de

0.1900 Se Existing bkf water surface slope

Sediment Transport Validation
7.05 Bankfull Shear Stress t~ =gRS (lb/ft2) where Density of water = g = 62.4 1bs/ft3
500 Moveable particle size (mm) at bankfull shear stress (predicted by Shields Diagram)
1.0 Predicted shear stress required to initiate movement of D; (mm) (see Shields Diagram)
Note: Particles lar er than the moveable article size at bankfull shear stress ma be mobilized.

1000

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.001 .002 .005 .01 .02 .05 .1 .2 .5 1 2 5 10
2c, CRITICAL SHEAR STRESS: pounds /square foot

Data points are drawn
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from the following 0 O
sources: O

U.S.W.E.S.
Chang
Nat'l. Bur. Stds. O
Kramer O
Indri
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NORTH
CHANNE
RELOCAT
30' BUFFER
Scale: 1:70
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Hard Rock Mine, Inc. DATE: REVISION:
Stream Restoration N,`; _~ ~~
--
+ ;~- ~ ~ ~ Wetland and Natural Resource Consultants
~~~~I, ~ ~ P.O. Box 882 Canton, N.C. 28716
Restoration Overview with Topo 828~88g01 PRELIMINARY PLANS
DO NOT USE FOR RECONSTRUCTION