20181446 Ver 1_Revised PCN Impacts_20191115

"W." will be used in the table below to represent the word "wetland".
2a1 Reason * (?)
2b. Impact type * (?)
2c. Type of W. *
2d. W. name*
2e. Forested *
2f. Type of
Jurisdicition*(?)
2g. Impact
area*
Im act W1
P
Excavation, Fill
T
Bottomland Hardwood Forest
Wetland A
Yes
Both
0.270
(acres)
Im act W1
P
Conversion
P
Bottomland Hardwood Forest
Wetland A
Yes
Both
0.160
(acres)
Impact W2
Excavation
T
Bottomland Hardwood Forest
Wetland B
Yes
Both
0.003
(acres)
Impact W2
Conversion
P
Bottomland Hardwood Forest
Wetland B
Yes
Both
0.002
(acres)
Impact W3
Excavation
T
Bottomland Hardwood Forest
Wetland E
Yes
Both
0.001
(acres)
Impact W3
Conversion
P
Bottomland Hardwood Forest
Wetland E
Yes
Both
0.001
(acres)
Impact W4
Excavation
T
Bottomland Hardwood Forest
Wetland F
Yes
Both
0.020
(acres)
Impact W4
Conversion
P
Bottomland Hardwood Forest
Wetland F
Yes
Both
0.010
(acres)
ffff�]F
nversion
P
Bottomland Hardwood Forest
nd
WetlaG
Yes
Both
0.002
(acres)
2g. Total Temporary Wetland Impact
0.294
2g. Total Permanent Wetland Impact
0.175
2g. Total Wetland Impact
0.469
2h. Comments:
Temporary wetland impacts associated with temporary open cut trench and temporary 45' wide construction corridor. Wetland areas will be returned to
original contours, stabilized, and allowed to re -vegetate.
Permanent wetland impacts associated with 20' wide permanent access corridor. Wetland areas will be returned to original contours and stabilized, but
Will be managed as a permanently cleared utility right-of-way.
3. Stream Impacts
If there are perennial or intermittent stream impacts (including temporary impacts) proposed on the site, then complete this question for all stream sites impacted.
"S." will be used in the table below to represent the word "stream".
3a. Reason for impact* (?) 3b.lmpact type * 3c. Type of impact* �3�name * 3e. Stream Type * �3f. Type of 3g. S. width* 3h. Impact
(?) Jurisdiction* length*
S1 Excavation for water line Temporary Excavation Pbrth Fork Swannanoa River Perennial Both 30 65 (linear feet)
�45
S7
Rip -rap bank protection
Permanent
Fill
Average (fit)
(linzarfeet>
fl
Excavation for water line
Temporary
Excavation
Fz,rN'�orth Fork SwannanoaPerennialBoth
Average (feet)
(linearfeet)
"All Perennial or Intermittent streams must be verified by DWR or delegated local government.
3i. Total jurisdictional ditch impact in square feet:
0
3i. Total permanent stream impacts:
45
31. Total temporary stream impacts:
105
31. Total stream and ditch impacts:
150
3j. Comments:
Temporary impacts associated with water line installation as open cut trench excavation. UT-1 beds and banks to be returned to original contours
and stabilized with coir matting, seeded with native seed mix, impacted stream bank areas outside of the permanent maintenance corridor will be live staked. N. Fork SwannanOa River bed to
be returned to original elevation, banks to be returned to original elevations and stabilized with coir matting, native seeding, and rip -rap.
E. Impact Justification and Mitigation '11�)

TEMPORARY ACCESS
STREAM IMPACT TABLE
S1 - PERM
NORTH FORK SWANNANOA RIVER
45-L.F.
S1 - TEMP
NORTH FORK SWANNANOA RIVER
65-L.F.
S3
UT-1 NORTH FORK SWANNANOA RIVER
40-L.F.
TOTAL
150-L.F.
WETLAND IMPACT TABLE
TEMPORARY
PERMANENT
IMPACT W1
WETLAND A
0.27 - ACRES
0.16 - ACRES
IMPACT W2
WETLAND B
0.003 - ACRES
0.002 - ACRES
IMPACT W3
WETLAND E
0.0007 - ACRES
0.0005 - ACRES
IMPACT W4
WETLAND F
0.02 - ACRES
0.01 -ACRES
IMPACT W5
WETLAND G
0.00 - ACRES
0.002 - ACRES
TOTALS
0.29 - ACRES
0.17 - ACRES
� (/l
TEMPORARY IMPACTS
® PERMANENT IMPACTS
I\
LIMITS O
DISTURBANCE
x�
CCCC WETLAND
y WETLAND C-
r
PERMANENTLY
MAINTAINE '
CORRIDOR - 24' WIDE
AI/
IMPACT W5-
1
0
P�
�P
5
Y WETLAND
ry
O
11
TEMPORARY
CONSTRUCTION
CORRIDOR - 45' WIDE
MPACT S1
PERMANENT
i
MPACT S1
TEMPORAI
�hC;/,/'
IMPACTS /
/ /
T-1 N FORK
Z i
/
SWANNANOA
RIVER
WETLAND E 5-
/
MPACT W3
//J l ill r
P Id "o
P
eK
1;'p%��1C aft
W4
IMPACT W
WETLAND B I )
TEMPORARY
CONSTRUCTIO i j / j/ / ,^ ., •° ... ✓�' I '
CORRIDOR - 45' WIDE
J GRAPHIC SCALE
-100 0 50 100
l
VIEW I INCH = 100 FEET
JURISDICTIONAL WETLANDS AND WATERS IDENTIFIED ON THIS MAP HAVE BEEN LOCATED WITHIN SUB -METER ACCURACY UTILIZING
A THALES MAPPING GRADE GLOBAL POSITIONAING SYSTEM (GPS) AND THE SUBSEQUENT DIFFERENTIAL CORRECTION OF THAT
DATA. GPS POINTS MAY DEMONSTRATE UNCORRECTABLE ERRORS DUE TO TOPOGRAPHY, VEGETATIVE COVER, AND/OR MULTIPATH
SIGNAL ERROR.
iT LIMITS OF NOTE: THE ILLUSTRATED WETLAND AND STREAM LOCATIONS ARE APPROXIMATE. THESE AREAS HAVE BEEN FLAGGED IN THE FIELD;
HOWEVER, THEY HAVE NOT BEEN SURVEYED. ALTHOUGH MCGILL ASSOCIATES, P.A. (MCGILL) IS CONFIDENT IN OUR ASSESSMENT,
DISTURBANCE THE US ARMY CORPS OF ENGINEERS IS THE ONLY AGENCY THAT CAN MAKE FINAL DECISIONS REGARDING JURISDICTIONAL
WETLAND AND WATERS OF THE US DELINEATIONS.
THIS MAP WAS PREPARED BY MCGILL USING THE BEST INFORMATION AVAILABLE TO MCGILL AT THE TIME OF PRODUCTION. THIS MAP
IS FOR INFORMATIONAL PURPOSES ONLY AND SHOULD NOT BE USED TO DETERMINE PRECISE BOUNDARIES, ROADWAYS, PROPERTY
BOUNDARY LINES, NOR LEGAL DESCRIPTIONS. THIS MAP SHALL NOT BE CONSTRUED TO BE AN OFFICIAL SURVEY OF ANY DATA
DEPICTED.
f
r SOURCE DATA: BUNCOMBE COUNTY GIB.
CITY OF ASHEVILLE NORTH FORK McGifl
IMPACT MAP PROJECT # WATER LINE PROJECT
17.00346 BLACK MOUNTAIN, NC A S S O C I A T E S
REVISED 11/15/19 BUNCOMBE COUNTY, ENVIRONMENTAL FINANCE
NORTH CAROLINA 1013 STATE FARM ROAD BOONE. NC 28607 PH. [phone]

USACE
Riprap sizing
Sf
1.1
Cs
0.3
CV
1
Crho
1
d
5.2 ft
Rhow
62.4lb/cf
Rhos
125 Ib/cf
K
1
g
32.2 ft/SA2
D30=
0.523279 ft
6.279348 inches
NCFMP North Fork Swanannoa HEC RAS LDS Model
crossing location is 300 ft US of section 224
d224
5.2 ft
d231
5.2 ft
flow
2320 cfs
channel V224
10.43 fps
channel V231
6.07 fps
RM distance
660 ft
RM ratio
0.45
V at
crossing 8.05
Note: Section 224 has more constricted channel and
higher V. Use V224
Therefore, NCDOT Class 2 is stable in FEMA base flood conditions.
TABLE 1042-1 - -- -- — -- - -
ACCEPTASCE CRITERIA FOR RIP RAP AND STONE FOR EROSION CONTROL
Class -- _ _Regnired Stone Sizes, inches
Minimum \lidrange_ vlaSimum
B 5 S 12
1 5 10 17
2 9 14 23
No more than 5.0% of the material filraished can be less than the mininnlm size specified nor
no more than 10.0% of the material can exceed the maximum size specified.
U.S. Army Corps of Engineers Riprap
Design for Flood Channels
STEPHEN T. MAYNORD
7be U.S. Army Corps of Engineers riprap design guidance for
flood channels is presented, and the limitstien, and bests of scv-
e 1 empirical—flia-mare discussed. The method is based on
depth -averaged velocity rather than shear stress, which was the
basis of the previous guialxnar. The effect, of bends, blanket
thickness, side -slope angle, particle shape, and gradation on rip -
rap stability ore addressed in the design guidance.
The U.S. Army Corps of Engineers guidance for design of
riprap in flood control channels is found in Engineer Manual
(EM) 1110-2-1601 (1). This guidattee is a departure from the
traditional guidance based on shear stress or tractive force
and uses a procedure based on local depth -averaged velocity.
Although the new method can be derived from a modificatian
of the shear stress equations, it does not use shear stress
explicitly. Local depth -averaged velocity was adopted pri-
marily because local shear stress is difficulc to visualize, com-
pute, and measure_ Various trscthods, discussed in this paper,
are available for estimating depth.averaged velocity. The ob-
jective of this paper is to provide assstanee in application of
the new procedure. Limitations of the method cold several
example problems will also be presented.
BASIC HQUA71`10N
The basis and derivation of the basic equation used to detcr-
mine stone size can be found in works by Maynard (2,3) and
Maynard et at. (4). From EM 1110-2.1601 (1) the equation
for determining stone size is
D„ = sc,C,crd Ll / n vV ' (t)
where
D,n = riprap size of which 30 percent is finer by weight
(far sorrto gradations, me DJ;
D, = D..(min)[D,,(min)rl;
Sf = safety factor (minimum = L 1);
Cs - stability coefficient for incipient failure, thick-
na = 1D,(msx) am t.sl?,j ), whk,haysr
is greater (DeIDr, = 1.7 to 5 2),
_ (1.30 for angular rock, and
- 0.375 for rounded rock [note: EM (1) is in
rest, giving 0,361;
DmID„ = gradation uniformity coefficient;
Cv = vertical velocity distribution coefficient,
- 1.0 for straight channels inside of bends,
1.733 - 0.2 tog (A!") fnr outside of bend
for R/W > 26),
= 1,25 downstream of concrete channels, ant
= t.25 at end of dikes;
R = centerline radius of atrvature of bend;
W = wate--surface width at upstream end of be-.
Cr = blanket thickness coefficient (see Figure 1)
d a local depth of flow;
y = unit weight of water;
Y, =—it weight of stone;
V = local depth -averaged velocity;
R, = side -slope correction factor; and
g = gravitational constant.
The power of 2.S in thin equation was based an IaMrs
data from straight, tilting flumes. The extreme values of
power in FAu i tim I arc from 2 to 3. A power of 2 resul
the Isbash equatie a (no dependence on depth) and is gent
used when there is no boundary layer development. A p,
of 3 results from application of existing shear stress anc
Manning -Strickler equations and represents the conditic
completely developed boundary layer and a relative to
ness (roughness si teldepth) that is low enough to yield a
slant Shields coeffucem. Because most bank and channel
rap protection problems fall somewhere between these
axtretnes, the 2.5 power was adopted for all bank and chs
riprap protection problems, not just the straight, tilting fit
from which it was derived.
INPUT/OUrPUr DESCRIPTION AND
LIMITATIONS
The method described henna is Insured to what is norn
referred to as "tow turbulent flow": the method is applie
to sizing riprap in rivers and channels except those imn
alely downstream of hydraulic structures that create hi
turbulent floss. Data used in the development of this me

RESLOPE EXISTING STREAM BANK TO ORIGINAL
CONTOURS AND STABILIZE WITH NATIVE PLANT SEED
MIX PER EROSION CONTROL NOTES.
INSTALL NORTH AMERICAN GREEN S-75BN MATTING OR
EQUAL ON STREAMBANK WHEN SEEDING IS COMPLETED.
X
Q
CONCRETE DEADMA
ANCHOR FABRIC 6' CLASS '2' RIP RAP iv
SEE DETAIL W21
INTO EARTH FILL
NORMAL STREAM LEVEL
1
FILTER FABRIC
MIRAFI 14ON OR
EQUAL.
RESTRAINT DEVICE
MEGALUG OR APPROVE EQUAL
DUCTILE IRON PIPE
RESTRAINT DEVICE
MEGALUG OR APPROVE EQUAL
SECTION VIEW
NOTES:
1. CONTRACTOR SHALL RESTRAIN AT LEAST 3
JOINTS PAST THE LAST FITTING AT THE TOP
OF THE BANK OR AS SPECIFIED BY ENGINEER.
2 APPROVED RESTRAINING DEVICES INCLUDE
RETAINING GLANDS (MEGALUGS), FIELD LOCK
GASKETS AND RESTRAINT SYSTEMS PROVIDED
BY APPROVED PIPE MANUFACTURERS.
3. SEE EC-37 DETAIL FOR ADDITIONAL
EROSION CONTROL MEASURES RELATED
TO CREEK CROSSING.
4. NO FERTILIZER SHALL BE USED WITHIN
OF BANK
WATERLINE CREEK CROSSING
35 UPDATED FEBRUARY, 2018
NOT TO SCALE