20181245 Ver 2_More Info Received_20200930

CLearWaLer
C1earWater Environmental Consultants, Inc.
www.cwenv.com
September 30, 2020
Ms. Sue Homewood
NCDEQ — Division of Water Resources
Winston Salem Regional Office
450 W. Hanes Mill Rd, Suite 300
Winston Salem NC 27105
RE: Tinsel Town Residential +1- 21 AC
Response to Additional Information Request
NC Division of Water Resources Project No. 20181245
Jackson County, North Carolina
Dear Ms. Homewood,
Please reference the additional information request letter issued by the NC Division of Water Resources
(DWR) on September 23, 2020 (Attachment A) in response to the permit modification request submitted
by C1earWater Environmental Consultants, Inc. (CEC), on behalf of Tinsel Town LLC, represented by
Mr. Wayne Smith. The permit modification was requested for a change in the southern portion of the site
plan to a mixture of commercial and residential development. The comments provided by DWR are
summarized and discussed below.
DWR Comment 1: "Please provide more details regarding avoidance and minimization of the impacts
for this project. [15A NCAC 02H.0506(b)]. "
a. "The plan sheets provided indicate that impacts to waters are proposed for the location
of a stormwater control measure. Please provide an analysis that documents all potential
options for stormwater management have been considered and that the project has
avoided and minimized all impacts to the maximum extent practical, including other
methods and/or locations for stormwater treatment. "
The applicant has modified the stormwater proposal. A subsurface infiltration system is now
proposed in an upland location that will not impact jurisdictional streams, wetlands, or open water
(Attachment B). The previously proposed stormwater control measure, a bioretention cell, has
been replaced with a substantially more costly subsurface infiltration system stormwater control
measure, with the same treatment capacity. A revised stormwater plan will be submitted to Ms.
Chonticha McDaniel at NC Division of Water Resources by Stillwell Engineering, P.A under a
separate cover letter.
b. "Please provide a more detailed plan sheet for the residential features on Parcel #1. It
appears that the structures could be placed in a different alignment and/or placed closer
together to avoid impacts. "
32 Clayton Street
Asheville, NC 28801
828-698-9800 Tel

There has been no change to the limits of the currently authorized impacts to waters associated
with this development. However, the southern portion of the site is proposed for a mixture of
commercial and residential use while the northern portion of the site remains consistent with the
original proposed site plan (Figure 5, Individual 401 Water Quality Certification application
submitted September 9, 2019). The revised site plan Parcel #1 (Attachment C; Figure 1.1) shows
five residential units, 20 parking spaces, and an open space for a playground. This layout is
consistent with the five residential units, 20 parking space, and open space that was previously
authorized in this portion of the site, albeit with a slight rearrangement to account for the new
secondary access road. A more detailed sheet is provided in Attachment C (Figure SWP.1).
DWR Comment 2; "The activity would not result in secondary or cumulative impacts that would cause a
violation of water quality standards. "
a. "Provide a detailed stormwater drainage plan (for parcel #1) including all stormwater
drainage patterns and outlets to clearly show that the project meets 15A NCAC 02H
.1003(2)(b) "stormwater shall be designed to maximize dispersed flow through vegetated
areas and minimize channel flow". In addition, according to 15A NCAC 02H.1003(2)(c)
"stormwater that cannot be released as dispersed flow shall be transported by vegetated
conveyances". Please identify all applicable vegetated areas and conveyances used in
order to meet the Low -Density criteria. Please note that impacts to waters of the state for
the purpose of meeting the Low -Density criteria would not meet the requirement of
avoidance and minimization. "
A detailed stormwater drainage plan for the southern portion of the site is included in Attachment
B. The residential development portion of the site meets criteria for low density development and
utilizes dispersed flow sheet flow through vegetated areas and vegetative conveyances in
accordance with 15A NCAC 02H .1003(2)(b) and (c). Vegetative conveyances are in accordance
with 15A NCAC 02H .1003(2)(b) with maximum 3:1 side slopes and are designed to contain
flow from the 10 year storm. A minimal amount of piping for roads and parking areas is
proposed for interconnection of vegetative conveyance measures also in accordance with 15A
NCAC 02H .1003(2)(b).
The applicant believes the information submitted in this package addresses all issues set forth by the
DWR in the additional information letter dated September 23, 2020. Should you have any questions or
comments concerning this project please do not hesitate to contact me at 828-698-9800.
Sincerely,
f �
Tyson Kurtz R. Clement Ri die, P.W.S
Biologist Principal

Attachment A
DWR Request for Additional Information
(dated September 23, 2020)

DocuSign Envelope ID: OCD9BFIC-4OD7-4F5E-A827-60045B16E71F
ROY COOPER
Governor
MICHAEL S. REGAN
Secretary
S. DANIEL SMITH
Director
NORTH CAROLINA
Environmental duality
September 23, 2020
DW R # 20181245 v2
Jackson County
Tinsel Town Inc
Attn: Wayne Smith
51 Bridge St
Sylva NC 28779
Subject: REQUEST FOR ADDITIONAL INFORMATION
Tinsel Town Residential Development
Dear Mr. Smith:
On August 24, 2020, the Division of Water Resources — Water Quality Programs (Division) received your
application for a modification of Water Quality Certification #WQC004191 issued on June 11, 2019. The
Division has determined that your application is incomplete and cannot be processed. The application is
on -hold until all of the following information is received:
1. Please provide more details regarding avoidance and minimization of the impacts for this
project. [15A NCAC 02H .0506(b)]
a. The plan sheets provided indicate that impacts to waters are proposed for the location
of a stormwater control measure. Please provide an analysis that documents all
potential options for stormwater management have been considered and that the
project has avoided and minimized all impacts to the maximum extent practical,
including other methods and/or locations for stormwater treatment.
b. Please provide a more detailed plan sheet for the residential features on Parcel #1. It
appears that the structures could be placed in a different alignment and/or placed
closer together to avoid impacts.
c. Please note that having conducted the impacts prior to modification request will not be
considered during the Division's review of the avoidance and minimization analysis.
2. The activity would not result in secondary or cumulative impacts that would cause a violation of
water quality standards.
North Carolina Department of Environmental Quality I Division of Water Resources
512 North Salisbury Street 1 1617 Mail Service Center I Raleigh, North Carolina 27699-1617
D E "
NORTH CAROLINA
919.707.9000

DocuSign Envelope ID: OCD9BF1C-40D7-4F5E-A827-60045B16E71F
Tinsel Town Inc
DWR Project #20181245 v2
Page 2 of 2
a. Provide a detailed stormwater drainage plan (for parcel#1) including all stormwater
drainage patterns and outlets to clearly show that the project meets 15A NCAC 02H
.1003(2)(b) "Stormwater shall be designed to maximize dispersed flow through
vegetated areas and minimize channel flow". In addition, according to 15A NCAC 02H
.1003(2)(c) "Stormwater that cannot be released as dispersed flow shall be transported
by vegetated conveyances". Please identify all applicable vegetated areas and
conveyances used in order to meet the Low Density criteria. Please note that impacts to
waters of the state for the purpose of meeting the Low Density criteria would not meet
the requirement of avoidance and minimization.
Pursuant to Title 15A NCAC 02H .0502(e), the applicant shall furnish all of the above requested
information for the proper consideration of the application. Please respond in writing within 30
calendar days of receipt of this letter by sending one (1) copy of all of the above requested information
to the 401 & Buffer Permitting Branch, 1617 Mail Service Center, Raleigh, NC 27699-1617 OR by
submitting all of the above requested information through this
link: https://edocs.deg.nc.gov/Forms/Supplemental-Information-Form (note the DWR# requested on
the link is referenced above).
If all of the requested information is not received within 30 calendar days of receipt of this letter, the
Division will be unable to approve the application and it will be denied as incomplete. The denial of this
project will necessitate reapplication to the Division for approval, including a complete application
package and the appropriate fee.
Please contact Sue Homewood at 336-776-9693 or Sue. [e-mail] if you have any
questions or concerns.
Sincerely,
DocuSi gned by:
eW W949D91BA53EF4E0...
Paul Wojoski, Supervisor
401 & Buffer Permitting Branch
cc: Clement Riddle, ClearWater Environmental Consultants (via email)
David Brown, USACE Asheville Regulatory Field Office (via email)
DWR ARO 401 files
DWR 401 & Buffer Permitting Unit

Attachment B
Stormwater Plan
(Dated September 28, 2020)

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PROPOSED LEGEND
(EXCEPT AS NOTED)
PARKING / STRIPING
RETAINING WALL
EDGE OF PAVEMENT
G
BOLLARD
TRAFFIC SIGN
M
LIMITS OF DISTURBANCE
■■■■■■■■■■■■■■■■■■
BUILDING ENVELOPE
SIDEWALK
TREE / LANDSCAPING
PARKING LOT LIGHTING
Q
CONTOUR
2150
STORM PIPE
ROOF DRAIN COLLECTOR
------------------
STORM WATER CATCH BASIN /
JUNCTION BOX
WATER LINE
SANITARY SEWER LINE
GATE VALVE AND BOX
SANITARY SEWER MANHOLE
SANITARY SEWER CLEANOUT
WATER SERVICE / METER
MJ TEE
EXISTING WATER LINE
SURVEY LEGEND
IPS - IRON PIN SET
IPF - IRON PIN FOUND
NIP - NEW IRON PIPE
EIP - EXISTING IRON PIPE
CMS - CONCRETE MONUMENT SET
CMF - CONCRETE MONUMENT FOUND
PP - POWER POLE
SP - SERVICE POLE
PT - POINT
R/W - RIGHT-OF-WAY
- FENCE
- CREEK OR WATERCOURSE
TOP OF RIDGE
TOR - TOP OF RIDGE
PROPOSED SPILLWAY
(PHASE 1)
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PROPOSED SILT FENCE - SEE DETAIL -[
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'�Z0�J IPROPOSED 4' BOTTOM WIDTH
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�j SITE AND GRADING NOTES:
1. ALL SITEWORK SHALL BE IN ACCORDANCE WITH RELEVANT JACKSON COUNTY ORDINANCES, STATE AND
NATIONAL REGULATORY STANDARDS AND ALL REQUIREMENTS.
2. CONTRACTOR IS RESPONSIBLE FOR COORDINATING ALL SITEWORK CONSTRUCTION AND SCHEDULING AS
REQUIRED TO PERMIT THE INSTALLATION OR CONSTRUCTION OF OTHER TRADES IN A LOGICAL SEQUENCE.
3. IT IS THE CONTRACTOR'S RESPONSIBILITY TO INSTALL AND MAINTAIN ADEQUATE EROSION CONTROL
DEVICES AS REQUIRED TO PREVENT ANY OFFSITE SEDIMENTATION, SILTATION OF CREEKS OR TRACKING OF
MUD OR DEBRIS ONTO PUBLIC ROADS. ALL EROSION CONTROL MEASURES SHALL BE IN ACCORDANCE
WITH THE NC SEDIMENTATION CONTROL COMMISSION, EROSION AND SEDIMENT CONTROL PLANNING
MANUAL, AND THE APPROVED DESIGN PLANS AND SPECIFICATIONS.
4. ALL PROPOSED FINISH ELEVATIONS ARE THE FINAL ELEVATIONS INDICATED FOR ASPHALT, CONCRETE OR
GROUND. SEE APPROPRIATE DETAILS TO DETERMINE SUBGRADE ELEVATIONS.
5. IT IS THE CONTRACTOR'S RESPONSIBILITY TO VERIFY ALL EXISTING AND PROPOSED DIMENSIONS AND
LOCATIONS OF DATA ILLUSTRATED IN THE PLANS IN THE FIELD PRIOR TO COMMENCING CONSTRUCTION OF
PROPOSED WORK. IF THESE PLANS DIFFER FROM ACTUAL FIELD CONDITIONS CREATING A CONFLICT FOR
INSTALLATION OF PROPOSED FACILITIES, IT IS THE CONTRACTOR'S RESPONSIBILITY TO NOTIFY THE
ENGINEER IMMEDIATELY PRIOR TO PROCEEDING WITH CONSTRUCTION.
6. CONTRACTOR SHALL BE RESPONSIBLE FOR ANY DAMAGE TO EXISTING ROADS DURING CONSTRUCTION AND
SHALL REPAIR ROADS PER REQUIREMENTS OF THE ROADWAY OWNER. REQUIRED PAVEMENT REMOVAL
SHALL BE MADE BY STRAIGHT EVEN CUTS AND SHALL BE PATCHED WITH STRAIGHT, EVEN EDGES.
ASPHALT PATCHES WITH ROUGH EDGES WILL NOT BE ACCEPTABLE AND SHALL BE REPAIRED AT NO
COST. NO OPEN CUTS OF EXISTING ROADS SHALL BE ALLOWED EXCEPT WHERE INDICATED ON THE
DRAWINGS. SAND OR SIMILAR MATERIALS APPROVED BY THE NCDOT SHALL BE PLACED AS A
PROTECTIVE BARRIER BETWEEN TRACK EQUIPMENT AND THE ROAD AND CLEANED UP PROPERLY AFTER
CONSTRUCTION.
7. ALL CONSTRUCTION SAFETY MEASURES SHALL BE IN ACCORDANCE WITH ALL LOCAL, STATE AND FEDERAL
REGULATORY STANDARDS AND ALL REQUIREMENTS IN THE PROJECT TECHNICAL SPECIFICATIONS.
8. THE CONTRACTOR SHALL PROVIDE, DURING CONSTRUCTION, AND ANY SUBSEQUENT MAINTENANCE,
PROPER SIGNS, SIGNAL LIGHTS, FLAGMEN AND OTHER WARNING DEVICES FOR THE PROTECTION OF
TRAFFIC IN CONFORMANCE WITH THE LATEST MANUAL ON UNIFORM TRAFFIC CONTROL DEVICES FOR
STREETS AND HIGHWAYS INCLUDING ANY SUBSEQUENT AMENDMENTS OR SUPPLEMENTS.
9. IT IS THE CONTRACTOR'S RESPONSIBILITY TO LOCATE ALL UTILITIES PRIOR TO CONSTRUCTION AND TO
NOTE ANY CONFLICTS. THE LOCATIONS OF UTILITIES SHOWN ON THE PLANS HAVE BEEN APPROXIMATED.
ALL BURIED UTILITIES ARE NOT SHOWN ON THE PLANS WHICH MAY INCLUDE POWER, PHONE, CABLE TV,
ETC. IT IS THE CONTRACTOR'S RESPONSIBILITY TO DETERMINE THEIR LOCATION PRIOR TO CONSTRUCTION.
ANY DAMAGE TO UTILITIES INCURRED DURING OR RESULTING FROM CONSTRUCTION ACTIVITY IS THE
RESPONSIBILITY OF THE CONTRACTOR AND IS TO BE REPAIRED AT THE CONTRACTOR'S EXPENSE. THE
CONTRACTOR IS TO NOTIFY ALL UTILITY COMPANIES AT LEAST 72 HOURS BEFORE CONSTRUCTION
ACTIVITY IS TO BEGIN. CALL NORTH CAROLINA ONE CALL 811.
10. IT IS THE CONTRACTOR'S RESPONSIBILITY TO PROTECT PUBLIC AND PRIVATE PROPERTIES THROUGHOUT
CONSTRUCTION. ANY DAMAGE TO PUBLIC OR PRIVATE PROPERTIES THAT IS A RESULT OF CONSTRUCTION
SHALL BE PROPERLY REPAIRED BY THE CONTRACTOR AT THE CONTRACTOR'S EXPENSE.
11. IT IS THE CONTRACTOR'S RESPONSIBILITY TO SCHEDULE AND COORDINATE ALL SITE VISITS BY THE
ENGINEER. THE CONTRACTOR SHALL NOTIFY THE ENGINEER AT LEAST THREE DAYS IN ADVANCE OF
INSPECTIONS REQUIRED BY PLANS AND SPECIFICATIONS.
12. ANY RIGHTS -OF -WAY, EASEMENTS AND PROPERTY DESCRIPTIONS OR ACQUISITIONS WHICH MAY BE
REQUIRED FOR THIS PROJECT ARE TO BE PROVIDED BY OTHERS.
13. PLANS ARE BASED UPON A TOPOGRAPHICAL SURVEY BY DAVENPORT, IVEY AND ASSOCIATES, INC.
DATED 5/18/17 WITH MINOR REVISIONS DATING UP TO 2/7/19. THESE PLANS SHOULD NOT BE USED FOR
THE SALE OR CONVEYANCE OF LAND OR RIGHT-OF-WAYS.
♦♦ �11��.-- '------------- --------------_-_----- ---- __- ` ��♦
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♦ ♦ CULVERT ��
♦♦ 18" n,� 0 BFE 2144.5 _-- - �`���� �� �� �� ��`. �♦♦♦ PROPOSED 6-INCH DIA. SCH. 40 PVC
♦♦ o - ___---''- + + + ` �♦� ROOF DRAIN COLLECTOR WITH CLEAN -OUTS
(♦ __ _______---' + + + + + + �!�♦ AS SHOWN - REFER TO ARCHITECTURAL
.\ \r�AZ�g1!P►�I 14"TRIPLE DRAWINGS FOR DOWNSPOUT CONNECTION
.. SYC,A40R€ -Q, f� 2146.9
+ + + + �� ♦� LOCATION AND DETAIL
1"4W1�\ \� 8 INCH ADS N12 WT HDPE
PLAYGROU / \•
COMMUNITY 50 �..� 261.20' C�? 0.34%
PARK 9.
AREA �♦
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...I,. /,.,....................................... 1 C//i N<` /� _ \ \ . _1 INVERT OUT EVATION� .. / i i30 FROM C/Li -
NCDOT STD. DWG. 840.02 / 840.03 TYPE E 18 INCH ADS N12 WT HDPE
CB-A5 INV IN = 2153.18 INV IN EL: 2153.18' 24 INCH ADS N12 WT HDPE 2152.93'
INV OUT = 2152.93
NCDOT STD. DWG. 840.02 / 840.03 TYPE E 24 INCH ADS N12 WT HDPE
CB-A4 INV IN = 2152.42 INV IN EL: 2152.42' 24 INCH ADS N12 WT HDPE 2152.42'
INV OUT = 2152.42
NCDOT STD DWG. 840.14 18 INCH ADS N12 WT HDPE
CB-11 INV IN = 2152.41 INV IN EL: 2152.41' 18 INCH ADS N12 WT HDPE 2152.41'
INV OUT = 2152.41
CB-10 NCDOT STD DWG. 840.14 18 INCH ADS N12 WT HDPE 2153.07'
INV OUT = 2153.07 EXISTING 18" CMP - VERIFY -
CB-A6 NCDOT STD. DWG. 840.02 / 840.03 TYPE E 18 INCH ADS N12 WT HDPE 2154.07'
INV OUT = 2154.07
NCDOT STD. DWG. 840.14 24 INCH ADS N12 WT HDPE
CB -Al INV IN = 2151.50 INV IN EL: 2151.50' 24 INCH ADS N12 WT HDPE 2151.50'
INV OUT = 2151.50
NCDOT STD. DWG 840.31
JB-2 INV IN = 2149.03 24 INCH ADS N12 WT HDPE 24 INCH ADS N12 WT HDPE 2151.53'
INV OUT = 2151.53 INV IN EL: 2149.03' 18 INCH ADS N12 WT HDPE 2152.01'
INV OUT = 2152.01
CB-A2-2 NCDOT STD. DWG. 840.02 / 840.03 TYPE E 24 INCH ADS N12 WT HDPE 2152.51'
INV OUT = 2152.51
OUTLET CONTROL STRUCTURE 18 INCH ADS N12 WT HDPE
OCS-1 INV IN = 2149.08 INV IN EL: 2149.08' 24 INCH ADS N12 WT HDPE 2149.08'
INV OUT = 2149.08
NCDOT STD. DWG. 840.14 24 INCH ADS N12 WT HDPE
CB-A2-1 INV IN = 2151.70 INV IN EL: 2151.70' 24 INCH ADS N12 WT HDPE 2151.70'
INV IN = 2152.34 24 INCH ADS N12 WT HDPE
INV OUT = 2151.70 INV IN EL: 2152.34'
NCDOT STD. DWG. 840.02 / 840.03 TYPE E 24 INCH ADS N12 WT HDPE
CB-A3 INV IN = 2151.80 INV IN EL: 2151.80' 24 INCH ADS N12 WT HDPE 2151.80'
INV OUT = 2151.80
FES-12 HDPE FLARED END SECTION 18 INCH ADS N12 WT HDPE
INV IN = 2150.16 INV IN EL: 2150.16'
FES-1 CONC 24 INCH ADS N12 WT HDPE
INV IN = 2148.11 INV IN EL: 2148.11'
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TITLE
STORMWATER PLAN
PROJECT NO.
20-0317
DRAWN BY
W.A.S.
CHECKED BY:
W.A.S.
SCALE
1:40
DATE 9/28/2020
SHEET:
swp.l
FOR REVIEW PURPOSES ONLY - NOT FOR CONSTRUCTION

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t=-- o���E; ,� o�= PE
0�1'.���SEE�E„���s,a,�,,wINCOMING 24-INCH DIA. HDPE
INV. EL: 2149.00DIA. HDPE X 2' LATERALSFROM HEADER TO ROWTRITON S29 HEADER ROW111 CHAMBERSOP INSPECTIONRT PER DETAILUNDERDRAINSOLID PIPE)TO OCS-1INCH DIA. HDPEC�? 1% GRADE
OUTLET TO OCS-1OUTLET CONTROL STRUCTUR DETAIL
STORM WATER MANAGEMENT CALCULATIONS
6-INCH DIA.
PERIMETER UNDERDRAIN
PER DETAIL
15 '"`"
IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII�
IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII
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_
TRITON S29 TREATMENT CHAMBER
A. BUILT UPON AREA (B.U.A.)
a. PARCEL #1:
• TOTAL PROPOSED PARCEL ACREAGE: 3.0 ACRES
• DEVELOPABLE PROPERTY EXCLUDING REMAINING STREAMS AND BUFFER ZONE: 2.31
ACRES
• RESIDENTIAL DEV. ADDED B.U.A.: 0.41 ACRES
• ACCESS ROAD ADDED B.U.A.: .14 ACRES
• TOTAL ADDED B.U.A.: 0.55 ACRES
• 0.55/2.31 AC AC = 23.98% B.U.A. - LOW DENSITY DEVELOPMENT
b. PARCEL #2:
• TOTAL PARCEL DEVELOPABLE ACREAGE: 3.23 ACRES
• POST -CONSTRUCTION B.U.A.: 2.35 ACRES
• 2.35 AC / 3.23 AC = 73 % B.U.A. - HIGH DENSITY DEVELOPMENT REQUIRED TO TREAT
RUNOFF FROM 1-INCH STORM EVENT FOR PROPOSED TRACTOR SUPPLY COMPANY SITE
ONLY. INCORPORATE BIORETENTION AREA FOR CONTROL AND TREATMENT:
1. REQUIRED VOLUME:
a. PRE-EXISTING IMPERVIOUS AREA:
GRAVEL SURFACE: 16,282 SF
STRUCTURES AND SLABS: 4,963 SF
TOTAL PRE-EXISTING IMPERVIOUS AREA: 21,245 SF = 0.49 ACRES
b. POST -CONSTRUCTION BUILT UPON AREA:2.35 ACRES
c. TOTAL NET BUILT UPON AREA ADDITION: 2.35 ACRES - 0.49 ACRES = 1.86 ACRES
d. TREATMENT VOLUME REQUIRED:
IMPERVIOUS FRACTION (Ia): 1.86 AC / 3.23 AC = 0.58
Rv = RUNOFF COEFFICIENT = 0.05 + 0.9 X la = 0.57
DESIGN VOLUME: 3,630 X Rv X Rd X A = 3,630 X 0..57 X 1 IN X 3.23 AC =
6,683 CF
PROVIDED BY PROPOSED INFILTRATION SYSTEM: 6,738 CF
e. INFILTRATION SYSTEM BOTTOM ELEVATION: 2,149.00'
CONCRETE WEIR
WITH ORIFICE
DISCHARGE TO
OUTLET
3'-0"
10„
PLAN
EMERGENCY
BYPASS PIPE
DER DRAIN
;'I!!!!!!!��OUTLET PIPE
DETENTION
DISCHARGE PIPE
RIM ELEVATION: 2156.00-\
STEEL-/
REINFORCED
CONCRETE WIER DETAIL
WEIR
3"
NOTES:
1. STRUCTURES TO BE CONSTRUCTED IN ACCORDANCE WITH 2O12
NCDOT STANDARD SPECIFICATIONS AND 2012 STANDARD
DRAWINGS 840.31 WITH WEIR ADDITION AS SHOWN.
2. RING AND COVER PER STANDARD DRAWING 840.54.
3. PRE -CAST MANUFACTURER TO SUBMIT DESIGN FOR APPROVAL
FOR WEIR W/ ORIFICE OPENING FOR APPROVAL FROM ENGINEER
PRIOR TO CONTRACTOR ORDERING.
STORM WATER DETENTION CONTROL
STRUCTURE (OCS-1) DETAIL
(N. T. S)
B. DRAINAGE DISCHARGE OUTFALL PROTECTION FROM 10 YR PEAK FLOW STORM.
1. DISCHARGE OUTFALL - FES-1
a. 10 YR STORM INTENSITY WITH TIME OF CONCENTRATION OF 5 MINUTES IS 6.65 IN/HR
PER NOAA STATION "CULLOWHEE"
b.
STORM WATER FLOW, Q = C*I*A WHERE C = COMPOSITE
RUNOFF COEFFICIENT
(0.95 -
ASPHALT/ROOF/CONCRETE); I = 6.65 IN/HR; A = 2.35
ACRES
c.
Q = 0.95 * 6.65 IN/HR * 2.35 AC = 14.85 CUBIC FEET
PER SECOND (CFS)
d.
DISCHARGE VELOCITY:
•
OUTFALL PIPE DIA: 24", MATERIAL: HDPE, n=.013
•
PIPE SLOPE: 2.32%
•
FOR PIPE FLOWING HALF FULL - Q = (1.49/.013) *1.57
* .5^(3) * .0232^1 =
17.19 CFS
•
USING CRITERIA FOR 2 FULL FLOW, OUTLET VELOCITY =
17.19 CFS/1.57 SF =
11.0 FT/S
•
PER FIGURES 8.06C AND 8.06D OF CHAPTER 8 OF THE NCDEQ EROSION AND
SEDIMENT
CONTROL PLANNING DESIGN MANUAL, REQUIRED STONE SIZE
IS CLASS I RIP RAP
TO BE
INSTALLED.
2. DISCHARGE OUTFALL FES-12
a. FLOW IS FROM A ROADWAY CULVERT CROSSING FERGUSON ROAD.
b. ESTIMATE FLOW FROM 10 YR STORM EVENT WITH TIME OF CONCENTRATION OF 5 MIN, I =
6.65 IN/HR FOR FERGUSON ROAD DRAINAGE INTO CULVERT DITCH
c. TOTAL PAVED AREA DRAINING TO CULVERT: 0.25 ACRES
d. ESTIMATED FLOW = Q = 0.95 * 6.65 IN/HR * 0.25 AC = 1.58 CFS
e. DESIGN OUTLET FLOW PROTECTION FOR VELOCITY RESULTING FROM 2 FULL PIPE FLOW.
e. DISCHARGE VELOCITY:
• OUTFALL PIPE DIA: 18", MATERIAL: HDPE, n=.013
• PIPE SLOPE: 1.13%
• FOR PIPE FLOWING HALF FULL - Q = (1.49/.013) * 0.883 SF * .375^(3) * .0113"2 =
5.60 CFS (4.0 CFS IN EXCESS OF ESTIMATED FLOW FROM ROAD CULVERT)
• USING CRITERIA FOR 2 FULL FLOW, OUTLET VELOCITY = 5.6 CFS/0.883 SF = 6.34 FT/S
• PER FIGURES 8.06C AND 8.06D OF CHAPTER 8 OF THE NCDEQ EROSION AND SEDIMENT
CONTROL PLANNING DESIGN MANUAL, USE CLASS A RIP RAP WITH APRON LENGTH OF 4
* 1.5FT = 6FT
-1 C I
IFICE DRAIN
STRUCTURE INVERT
ELEVATION: 2149.00'
GRASS LINED SWALES
(N. T. S)
NOTE:
1. GRASS TO BE EITHER TALL
FESCUE OR KENTUCKY BLUE
GRASS.
C. PARCEL NO. 1 DRAINAGE SWALES
10 YR STORM INTENSITY WITH TIME OF CONCENTRATION OF 5 MINUTES IS 6.65 IN/HR (1) PER
NOAA STATION "CULLOWHEE"
STORM WATER FLOW, Q = C*I*A WHERE C = COMPOSITE RUNOFF COEFFICIENT (0.6 -
RESIDENTIAL MULTI -UNITS DETACHED); I = 6.65 IN/HR; A = 1.05 ACRES Q = 4.15 CFS
DESIGN FOR SWALES IS 4 FOOT WIDE BOTTOM WITH 3:1 SIDE SLOPES, 2 FEET DEEP FOR A
TOTAL DITCH WIDTH OF 16 FEET.
SWALE LINING IS KENTUCKY BLUE GRASS OR TALL FESCUE WITH RETARDANCE CLASS C WITH
A ROUGHNESS COEFF. OF 0.14. SLOPES ARE LESS THAN 5% WITH PERMISSIBLE VELOCITY OF
4.5 FT/SEC
1. DRAINAGE SWALE A
GRADE: 1.93%
FLOW
DEPTH
AT
4.15 CFS IS APPROXIMATELY 0.713 FT:
A =
4*0.713
+
3*.0713 = 4.38 SF
R =
4.38 SF
/
4 + 2*.713*(10)/"3 = 0.514 FT
V = 1.49/.14 * 0.514�3 * (.0193)^0.5 = 0.95 FT/SEC WHICH IS BELOW MAX. PERM. VELOCITY
2. DRAINAGE SWALE B
GRADE: 2.10%
FLOW
DEPTH
AT
4.15 CFS IS APPROXIMATELY 0.697 FT:
A =
4*0.697
+
3*.0697 = 4.25 SF
R =
4.25 SF
/
4 + 2*.697*(10)/,3 = 0.505 FT
V = 1.49/.14 * 0.505^3 * (.02.10)-0.5 = 0.98 FT/SEC WHICH IS BELOW MAX. PERM.
VELOCITY
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TITLE
STORM WATER TREATMENT
SYSTEM AND
STORM WATER CALCULATIONS
PROJECT NO.
20-0317
DRAWN BY:
W.A.S.
CHECKED BY:
W.A.S.
SCALE
NONE
DATE 9/28/2020
SHEET
SWP.2
FOR REVIEW PURPOSES ONLY - NOT FOR CONSTRUCTION

Attachment C
Revised Impact Map
(Dated September 28, 2020)

01
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RACTOR SUPPLY COMPANY ADDED B.U.A.: 2.35 ACR
1% B.U.A.
YSTEM - PARCEL #2
PT END 30" CMP
TOTAL PROJECT AREA + /- 22.31 ACRES
JURISDICTIONAL WATERS OF THE U.S.
STREAMS
WETLANDS
OPEN WATER
2875 LF
5.53 ACRES
3.33 ACRES
JURISDICTIONAL IMPACTS
OPEN WATER (PERMANENT)
WETLANDS
STREAMS (PERMANENT):
STREAMS (TEMPORARY):
AVOIDANCE/MINIMIZATION
2.68 ACRES
0.0 ACRES
42 LF
17 LF
OPEN WATERS 0.65 ACRES
WETLANDS 5.53 ACRES
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TITLE
IMPACT SITE PLAN
PROJECT N0.
18-0627
DRAWN BY
W.A.S.
CHECKED BY:
W.A.S.
SCALE
AS SHOWN
DATE :
9 28 2020
SHEET:
1.1
PRELIMINARY FOR REVIEW PURPOSES ONLY