SWA000081_15.00391 Stormwater Report - Sealed_20201116

DESIGN REPORT
STORMWATER MANAGEMENT PLAN
Horsepasture River
Wastewater Treatment Plant and Collection System
Improvements
JacksonCounty, North Carolina
2020
_________________________________________
Scott Burwell, PE
NC Professional Engineer No. 039177
McGill Associates, P.A.
55 Broad Street
Asheville, NC 28801
License Number C-0459
3131/19/35!
24;31;3:!
.15(11(
AUGUST2020

STORMWATER MANAGEMENT PLAN
HORSEPASTURE RIVER
WASTEWATER TREATMENT PLANT AND COLLECTION SYSTEM IMPROVEMENTS
JACKSON COUNTY, NORTH CAROLINA

1.1PROJECT DESCRIPTION ................................................................................................. 3
1.2 SITE DESCRIPTION........................................................................................................... 3
1.3 ADJACENT PROPERTY .................................................................................................... 3
1.4 SOILS ................................................................................................................................. 3
1.5 STORMWATER CONTROL MEASURES .......................................................................... 4
APPENDICES
APPENDIXASITELOCATIONMAP
APPENDIXBDEED(S)
APPENDIXCCALCULATIONS:WETPOND
APPENDIXDCALCULATIONS:PIPES
APPENDIXECALCULATIONS:OUTLETPROTECTION
APPENDIXFRAINFALLANDSOILSDATA
APPENDIXGDRAINAGEAREAMAPS

1.1 PROJECT DESCRIPTION

Theprojectconsistsoftheconstructionofanewwastewatertreatmentplantonthe
HorsepastureRiverandimprovementsofthecollectionsystem.Theprojectislocatedonthe
HorsepastureRiverinCashiers,JacksonCounty,NorthCarolina.Duetoexcesswastewaterflows,
theTuckaseigeeWaterandSewerAuthority(TWSA)sawanimmediateneedforincreased
wastewatercollectionandtreatmentcapacityintheCashiersservicearea.Thesitewillbe
accessedfromacrossHorsepastureRiveronUSHighway64.Inordertoreachthesite,a
temporarystreamcrossingwillbeconstructedtoaidintheconstructionofanewpermanent
bridge.Oncethebridgeconstructioniscomplete,thetemporarystreamcrossingwillbe
removedandthestreamwillberestoredtoitsnaturalcondition.
FinanciallyResponsibleParty:
TuckaseigeeWaterandSewerAuthority
1246WestMainStreet
Sylva,NorthCarolina28779
Contact:
Mr.DanielManring
ExecutiveDirector
(828)5865189
1.2 SITE DESCRIPTION
The project site can be described as predominately high sloped wooded area. The average slope
of the site south of the Horsepasture River is 17%. The average slope around the Horsepasture
River is 2%. The grading operations will occur where proposed grades are shown on the plans.
The site drains towards the Horsepasture River and runoff will collect into a proposed wetpond
before discharging into the river. The site lies within a state-defined ÐOutstanding Water
Resources AreaÑ, therefore all stomwater management devices have been designed for the 25-
year, 24-hour storm event.
1.3 ADJACENT PROPERTY
The surrounding properties of the site are best described as predominately wooded with a few
residential, single-family lots on the east side. The property across US 64 E is grass.
1.4 SOILS
The extents of the project site contain soils with the following map unit names: Nikwasi fine sandy
loam, 0 to 2 percent slopes, frequently flooded, group A/D (NkA), and Saunook gravelly loam, 15
to 30 percent slopes, group B (SaD).

1.5 STORMWATER CONTROL MEASURES
A wetpond was selected as the primary stormwater control measure for this project to satisfy
volume and flow match requirements. Based on post-construction conditions, all runoff within the
improved drainage areas will be captured and detained in the proposed wetpond. The wetpond is
sized to treat the runoff from the 25-year design storm from all proposed built-upon areas
associated with the project. All offsite stormwater runoff will bypassed around the project area and
will not be treated.

APPENDIX A
SITE LOCATION MAP

APPENDIX B
DEED(S)

APPENDIX C
WETPOND CALCULATIONS

WET POND CALCULATIONS Horsepasture River Wastewater Treatment Plant
(Procedure and Calculations taken from NCDEQ Stormwater BMP Manual, 7/18/19 Revision)Jackson County, NC
7-May-20
Step 1:Solve for R & Design Volume
V
Step 2:Assume Permanent pool Average Depth, determine SA/DA ratio and calculate required minimum surface area (SA)
Step 3:Using CAD design and minimum SA, calculated average depth
Step 4:
Check if d> Assumed. If so, design is good.
av
Step 5:If d< Assumed, then assume greater depth and go back to Step 2
av
Step 6:Confirm design volume requirement met
Step 7:Confirm orifice size for 2-5 drawdown requirement
Step 8:Verify Forebay Size
Step 1: Solve for Rv & Design Volume
Total DA =3.77acres
DA-IMP =1.66acres
IA=44.10%
R 0.050.9 I
VA
V 3630 RRA
min DV
R= Rainfall Depth
Rv = Runoff Coefficient1.00 in
D
IA = Impervious FractionV= 6114.87 cf
min
Rv =0.45
SA
SADA 43560
min
DA
Step 2: Determine minimum Surface Area
ASSUMED PERMANENT POOL DEPTH =
3'
SA / DA =1.51%
SA = 2479.25 sf
min
Steps 3 - 5: Determine average depth and compare to assumption
d= V/SA*Use if shelf is not submerged (Equation 2)
av pp
d= VV/A*Use if shelf is partially or completely submerged (Equation 3)
av pp - shelfbottomofshelf

Equation 2 (Values from actual CAD design)Equation 3 (Values from actual CAD design)
Depth
V=17111.5*Main Pool OnlyV=
maxovershelf
pppp
Perimeter
SA=5071.4 OK V=0
permpool
shelf
Width
d=3.37 OK A=
submergedpartofshelf
avbottomofshelf
d=#DIV/0!#DIV/0!
av
Step 6: Confirm design volume requirement is met
Elevation
SA=
10111.05Temporary Pool Surface Area3193
tp
SA=
5071.4Permanent Pool Surface Area3190
pp
Depth=
3Depth of Temporary Pool (Distance from TP to PP)
tp
Volume=
22774 OK
tp
Step 7: Confirm draw down requirement met (2-5 days)
Volume=
22774 cf
tp
3.00 ft
HW=
HW/3=1.00 ft
Orifice Size=2in
Q=0.10 cfs
Dewatering Time (Hours)=60.25 OK
Dewatering Time (Days)=2.51
Step 8: Verify Forebay Volume Sizing (15-20% of Main Pool Volume)
Volume=
2750.8cf
forebay
Volume=
17112 cf
mainpool
Volume %=16%OK
Step 9: Emergency Spillway Sizing
Q50=28.33cfs
Spillway Depth=1ft
Spillway Length=12ft
Spillway Capacity=33.60 cfs OK

on dimensionvolume provided (ft^3)Factor of safety
Block
floatation
Anti
Concrete
148" Pre-cast box259.5237.51482098.88' x 8' x 3'1921.943319838
150lb/cf concrete
62.4lb/cf water
basin idriser area (ft^2)height (ft)volume (ft^3)weight of water displaced (lbs)volume of concrete required (ft^3)anti-floatati

1S
2S
Pre-Development
Post-Development 1
1P
Wet Pond
Routing Diagram for 15.00391-Wet Pond-NC
Reach
SubcatPond
Link
Prepared by McGill & Associates, Printed 10/29/2020
HydroCAD® 10.00-16 s/n 04263 © 2015 HydroCAD Software Solutions LLC

15.00391-Wet Pond-NC
Printed 10/29/2020
Prepared by McGill & Associates
HydroCAD® 10.00-16 s/n 04263 © 2015 HydroCAD Software Solutions LLC
Page 2
Area Listing (all nodes)
AreaCNDescription
(sq-miles)(subcatchment-numbers)
0.00336950-75% Grass cover, Fair, HSG B (2S)
0.002698Paved parking & roofs (2S)
0.005960Woods, Fair, HSG B (1S)
0.011871TOTAL AREA

15.00391-Wet Pond-NC
Printed 10/29/2020
Prepared by McGill & Associates
HydroCAD® 10.00-16 s/n 04263 © 2015 HydroCAD Software Solutions LLC
Page 3
Soil Listing (all nodes)
AreaSoilSubcatchment
(sq-miles)GroupNumbers
0.0000HSG A
0.0092HSG B1S, 2S
0.0000HSG C
0.0000HSG D
0.0026Other2S
0.0118TOTAL AREA

15.00391-Wet Pond-NC
Printed 10/29/2020
Prepared by McGill & Associates
HydroCAD® 10.00-16 s/n 04263 © 2015 HydroCAD Software Solutions LLC
Page 4
Ground Covers (all nodes)
HSG-AHSG-BHSG-CHSG-DOtherTotalGroundSubcatchment
(sq-miles)(sq-miles)(sq-miles)(sq-miles)(sq-miles)(sq-miles)CoverNumbers
0.00000.00330.00000.00000.00000.003350-75% Grass cover, Fair2S
0.00000.00000.00000.00000.00260.0026Paved parking & roofs2S
0.00000.00590.00000.00000.00000.0059Woods, Fair1S
0.00000.00920.00000.00000.00260.0118TOTAL AREA

15.00391-Wet Pond-NC
Printed 10/29/2020
Prepared by McGill & Associates
HydroCAD® 10.00-16 s/n 04263 © 2015 HydroCAD Software Solutions LLC
Page 5
Pipe Listing (all nodes)
Line#NodeIn-InvertOut-InvertLengthSlopenDiam/WidthHeightInside-Fill
Number(feet)(feet)(feet)(ft/ft)(inches)(inches)(inches)
11P3,185.003,179.0075.00.08000.01124.00.00.0

Type II 24-hr 25-yr Rainfall=10.10"
15.00391-Wet Pond-NC
Printed 10/29/2020
Prepared by McGill & Associates
HydroCAD® 10.00-16 s/n 04263 © 2015 HydroCAD Software Solutions LLC
Page 6
Time span=0.00-96.00 hrs, dt=0.10 hrs, 961 points
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Runoff Area=164,189 sf Runoff Depth=4.98"
Subcatchment 1S: Pre-Development
Tc=0.250 hrs CN=60 Runoff=23.29 cfs 1.564 af
Runoff Area=164,189 sf Runoff Depth=7.87"
Subcatchment 2S: Post-Development 1
Tc=0.250 hrs CN=82 Runoff=35.19 cfs 2.473 af
Peak Elev=3,192.78' Storage=38,743 cf Inflow=35.19 cfs 2.473 af
Pond 1P: Wet Pond
Outflow=22.69 cfs 2.080 af
Total Runoff Area = 0.0118 sm Runoff Volume = 4.037 af Average Runoff Depth = 6.43"

Type II 24-hr 25-yr Rainfall=10.10"
15.00391-Wet Pond-NC
Printed 10/29/2020
Prepared by McGill & Associates
HydroCAD® 10.00-16 s/n 04263 © 2015 HydroCAD Software Solutions LLC
Page 7
Summary for Subcatchment 1S: Pre-Development
Runoff=23.29 cfs @ 12.08 hrs, Volume=1.564 af, Depth=4.98"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-96.00 hrs, dt= 0.10 hrs
Type II 24-hr 25-yr Rainfall=10.10"
Area (sf)CNDescription
164,18960Woods, Fair, HSG B
TcLengthSlopeVelocityCapacityDescription
(hours)(feet)(ft/ft)(ft/sec)(cfs)
0.250
Direct Entry, 15 min assumption
Subcatchment 1S: Pre-Development
Hydrograph
26
Runoff
25
23.29 cfs
24
23
Type II 24-hr
22
21
25-yr Rainfall=10.10"
20
19
Runoff Area=164,189 sf
18
17
16
Runoff Volume=1.564 af
15
14
Runoff Depth=4.98"
13
12
Tc=0.250 hrs
Flow (cfs)
11
10
CN=60
9
8
7
6
5
4
3
2
1
0
05101520253035404550556065707580859095
Time (hours)

Type II 24-hr 25-yr Rainfall=10.10"
15.00391-Wet Pond-NC
Printed 10/29/2020
Prepared by McGill & Associates
HydroCAD® 10.00-16 s/n 04263 © 2015 HydroCAD Software Solutions LLC
Page 8
Summary for Subcatchment 2S: Post-Development 1
Runoff=35.19 cfs @ 12.07 hrs, Volume=2.473 af, Depth=7.87"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-96.00 hrs, dt= 0.10 hrs
Type II 24-hr 25-yr Rainfall=10.10"
Area (sf)CNDescription
91,7796950-75% Grass cover, Fair, HSG B
72,41098Paved parking & roofs
164,18982Weighted Average
TcLengthSlopeVelocityCapacityDescription
(hours)(feet)(ft/ft)(ft/sec)(cfs)
0.250
Direct Entry, 15 min assumption
Subcatchment 2S: Post-Development 1
Hydrograph
Runoff
38
35.19 cfs
36
Type II 24-hr
34
32
25-yr Rainfall=10.10"
30
28
Runoff Area=164,189 sf
26
Runoff Volume=2.473 af
24
22
Runoff Depth=7.87"
20
18
Tc=0.250 hrs
Flow (cfs)
16
CN=82
14
12
10
8
6
4
2
0
05101520253035404550556065707580859095
Time (hours)

Type II 24-hr 25-yr Rainfall=10.10"
15.00391-Wet Pond-NC
Printed 10/29/2020
Prepared by McGill & Associates
HydroCAD® 10.00-16 s/n 04263 © 2015 HydroCAD Software Solutions LLC
Page 9
Summary for Pond 1P: Wet Pond
Inflow Area =0.0059 sm, Inflow Depth = 7.87" for 25-yr event
Inflow=35.19 cfs @ 12.07 hrs, Volume=2.473 af
Outflow=22.69 cfs @ 12.21 hrs, Volume=2.080 af, Atten= 36%, Lag= 8.7 min
Primary=22.69 cfs @ 12.21 hrs, Volume=2.080 af
Routing by Stor-Ind method, Time Span= 0.00-96.00 hrs, dt= 0.10 hrs
Peak Elev= 3,192.78' @ 12.23 hrs Surf.Area= 9,867 sf Storage= 38,743 cf
Plug-Flow detention time= 122.2 min calculated for 2.080 af (84% of inflow)
Center-of-Mass det. time= 51.9 min ( 847.0 - 795.1 )
VolumeInvertAvail.StorageStorage Description
#13,185.00'51,828 cf Custom Stage Data (Prismatic) Listed below (Recalc)
ElevationSurf.AreaInc.StoreCum.Store
(feet)(sq-ft)(cubic-feet)(cubic-feet)
3,185.001,76900
3,190.005,07017,09817,098
3,191.007,4506,26023,358
3,194.0011,53028,47051,828
DeviceRouting InvertOutlet Devices
#1Primary3,185.00'
24.0" Round RCP_Round 24"
L= 75.0' RCP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 3,185.00' / 3,179.00' S= 0.0800 '/' Cc= 0.900
n= 0.011 Concrete pipe, straight & clean, Flow Area= 3.14 sf
#2Device 13,190.00'18.0" W x 4.0" H Vert. Orifice/Grate X 4.00 C= 0.600
#3Device 13,192.50' C= 0.600
48.0" x 48.0" Horiz. Orifice/Grate
Limited to weir flow at low heads
#4Primary3,193.00'
26.6 deg x 12.0' long x 1.00' rise Sharp-Crested Vee/Trap Weir
Cv= 2.63 (C= 3.29)
Max=21.79 cfs @ 12.21 hrs HW=3,192.74' (Free Discharge)
Primary OutFlow
(Passes 21.79 cfs of 39.28 cfs potential flow)
1=RCP_Round 24"
(Orifice Controls 15.46 cfs @ 7.73 fps)
2=Orifice/Grate
(Weir Controls 6.33 cfs @ 1.62 fps)
3=Orifice/Grate
( Controls 0.00 cfs)
4=Sharp-Crested Vee/Trap Weir

Type II 24-hr 25-yr Rainfall=10.10"
15.00391-Wet Pond-NC
Printed 10/29/2020
Prepared by McGill & Associates
HydroCAD® 10.00-16 s/n 04263 © 2015 HydroCAD Software Solutions LLC
Page 10
Pond 1P: Wet Pond
Hydrograph
Inflow
Primary
35.19 cfs
38
36
Inflow Area=0.0059 sm
34
Peak Elev=3,192.78'
32
30
Storage=38,743 cf
28
26
22.69 cfs
24
22
20
18
Flow (cfs)
16
14
12
10
8
6
4
2
0
05101520253035404550556065707580859095
Time (hours)

APPENDIX D
PIPE CALCULATIONS

!!!!!
g's
ing's
Factor
Controlling
Design Outcomes
Pipe Size
Comment
Adequacy
(CFS)
Capacity
Inlet Control
(CFS)
Capacity
Manning's
(y)
Inlet
Constant
(c)
Inlet
Constant
Inlet
HDS-5
Ref. No.
(FT)
Available
Headwater
Manning's and Inlet Control Values
Pipe Slope
Coef. (n)
Roughness
Pipe
Material
Pipe ID
Total (CFS)
(CFS)
Incremental
(IN/HR)
Rainfall
Intensity
Runoff
Coef. (C)
Weighted
Rational Method Calculation Q = CiA
Drainage
Area (AC)
& depth.
Hydraulic Design of Highway Culverts
Diameter (IN)
Inv. Out
Bevel Bevel
oo
(FT)
Length
Rim
Pipe Characteristics
Structure
Upstream
CMP, ProjectingCircular, Beveled Ring, 45Circular, Beveled Ring, 37
1RCP, Square edge w/headwall 2RCP, Groove w/headwall 3RCP, Groove End Projecting 4CMP, Headwall5CMP, Mitered to Slope678
Structure ID
Downstream
STORM DRAIN PIPES
Temporary Stream CrossingTemporary Stream CrossingTemporary Stream CrossingTemporary Stream CrossingTemporary Stream Crossing
Upstream
Structure ID
L:\\Broadstreet\\Projects\\2015\\15.00391\\misc\\Civil Site Plan\\Stormwater\\15.00391 - Pipe Calcs
1CB #1CB #23222.6584.353219.093218.251843050.100.679.600.630.631HDPE0.0111.00%3.5610.04500.6912.3913.26OKManning's2CB #2CB #33222.43133.583218.153216.8218159450.370.689.602.403.032HDPE0.0111.00%4.281
0.04500.6912.3915.02OKManning's3CB #3CB #43222.5472.313216.723216.0018158190.360.619.602.115.143HDPE0.0111.00%5.8210.04500.6912.3918.24OKManning's4CB #4CB #53222.8283.223215.903213.881849430.110.589.
600.635.774HDPE0.0112.43%6.9210.04500.6919.3420.24OKManning's5CB #5CB #63217.5928.53213.783211.501861970.140.489.600.666.435HDPE0.0118.00%3.8110.04500.6935.1114.03OKInlet6CB #6CB #113215.0788.833210.
623200.5018235600.540.519.602.659.096HDPE0.01111.39%4.4510.04500.6941.9015.59OKInlet7CB #7CB #83207.3393.673203.763202.8218125160.290.729.601.991.997HDPE0.0111.00%3.5710.04500.6912.4413.28OKManning's
8CB #8CB #93207.37121.893202.723201.501894140.220.729.601.493.488HDPE0.0111.00%4.6510.04500.6912.4215.86OKManning's9CB #9CB #103207.1680.483201.403200.5918124310.290.679.601.845.329HDPE0.0111.01%5.76
10.04500.6912.4518.12OKManning's
10CB #10CB #113208.19128.313200.493199.211834320.080.499.600.375.6910HDPE0.0111.00%7.7010.04500.6912.4021.52OKManning's11CB #11CB #123205.2335.683199.113198.501878120.180.469.600.7915.5711HDPE0.0111.
71%6.1210.04500.6916.2318.81OKManning's12CB #12JB #13202.2058.823197.503186.861860410.140.619.600.8216.3912HDPE0.01118.09%4.7010.04500.6952.8016.24No GoodInlet13JB #1HW #13190.4811.513185.703185.5018
00.000.009.600.0016.3913HDPE0.0111.74%4.7810.04500.6916.3616.15No GoodInlet16JB #2JB #33182.8891.883178.493176.031800.00#DIV/0!9.600.009.0516RCP0.0122.68%4.3910.04500.6918.6215.30OKInlet17HW
#4JB #33179.0848.753176.503176.0324149360.340.369.601.1913.0917RCP0.0120.96%2.5810.04500.6924.0616.29OKInlet18JB #3HW #53183.6223.383175.933175.702400.00#DIV/0!9.600.0022.1518RCP0.0120.98%7.6910.045
00.6924.3137.23OKManning's
EX 1EX HWJB #23182.0035.223179.343178.5918See Note 3#VALUE!#VALUE!9.609.059.05EX 1CMP0.0222.13%2.6610.04500.699.0610.67OKManninEX 2EX HWEX HW3182.0041.63178.103177.7724See Note 3#VALUE!#VALUE!9.6011.
9011.90EX 2CMP0.0220.79%3.9010.04500.6911.9123.55OKMann
14(1)HW #2HW #33197.9047.873195.003191.00242802456.430.309.6018.6118.6114(1)HDPE0.0118.36%2.9010.04500.6977.2818.75OKInlet14(2)HW #2HW #33197.9047.873195.003191.00242802456.430.309.6018.6118.6114(2)H
DPE0.0118.36%2.9010.04500.6977.2818.75OKInlet15(1)64.943175.003174.0048See Note 4#VALUE!#VALUE!9.60#VALUE!#VALUE!15(1)HDPE0.0111.54%-3,175.0010.04500.69210.66#NUM!#NUM!#NUM15(2)63.993175.003174.0048S
ee Note 4#VALUE!#VALUE!9.60#VALUE!#VALUE!15(2)HDPE0.0111.56%-3,175.0010.04500.69212.22#NUM!#NUM!#NUM15(3)63.073175.003174.0048See Note 4#VALUE!#VALUE!9.60#VALUE!#VALUE!15(3)HDPE0.0111.59%-3,175.0010.
04500.69213.76#NUM!#NUM!#NUM15(4)62.093175.003174.0048See Note 4#VALUE!#VALUE!9.60#VALUE!#VALUE!15(4)HDPE0.0111.61%-3,175.0010.04500.69215.44#NUM!#NUM!#NUM15(5)61.153175.003174.0048See
Note 4#VALUE!#VALUE!9.60#VALUE!#VALUE!15(5)HDPE0.0111.64%-3,175.0010.04500.69217.09#NUM!#NUM!#NUM
Pipe IDInv. InDrainage Area (SF)
Notes:1. Inlet control capacities are calculated using Equation 28 located in the Federal Highway Administration publication HDS-5 -2. Calculations do not take into account reduced
flow on account of oversized pipe and outlet control structure.3. Assumed flow of existing storm pipes crossing under US HWY-64 were determined by full pipe capacity at their as-built
slope 4. See plan sheets for Temporary Stream Crossing details.5. HDS-5 Inlet Reference Numbers are as follows:

APPENDIX E
OUTLET PROTECTION CALCULATIONS

New York DOT Dissipator Method For Use in Defined Channels
Guide to Color Key:User Input DataCalculated ValueReference Data
Designed By:NLC Date:5.28.20
Checked By:SEB Date:
Company:McGill Associates
Project Name:Horsepasture WWTP
Project No.:15.00391
Site Location (City/Town)Cashiers, NC
Culvert Id.HW #1
Estimation of Stone Size and Dimensions For Culvert Aprons
Velocity (ft/s)9.19
Pipe Culvert
Opening type
Single or multiple openings?Single
(ft)
Outlet pipe diameter, D
1.5
o
NOTE 1: If opening type is anything other than "Pipe Culvert", D=A (Cross-
oo
sectional area of flow at outlet).
NOTE 2: If multiple openings, D=1.25 x D of single culvert.
oo
Zone2Figure 8.06c
Will apron have >/=10% grade?Yes
NOTE: For apron slopes equal to or greater than 10%, use next higher Zone in Figure 8.06d to determine
apron length.
Apron length (ft)6Figure 8.06d
Determination of Stone Sizes For Dumped Stone Channel Linings and
Revetments
e
Max. stone size (in.)12Figure 8.06e
Min. & max range of stones (lbs)25-150Figure 8.05f
Weight range of 75% of stones (lbs)50-150Figure 8.05f

New York DOT Dissipator Method For Use in Defined Channels
Guide to Color Key:User Input DataCalculated ValueReference Data
Designed By:NLC Date:6.1.20
Checked By:SEB Date:
Company:McGill Associates
Project Name:Horsepasture WWTP
Project No.:15.00391
Site Location (City/Town)Cashiers, NC
Culvert Id.HW #5
Estimation of Stone Size and Dimensions For Culvert Aprons
Velocity (ft/s)6.98
Pipe Culvert
Opening type
Single or multiple openings?Single
(ft)
Outlet pipe diameter, D
2
o
NOTE 1: If opening type is anything other than "Pipe Culvert", D=A (Cross-
oo
sectional area of flow at outlet).
NOTE 2: If multiple openings, D=1.25 x D of single culvert.
oo
Zone2Figure 8.06c
Will apron have >/=10% grade?Yes
NOTE: For apron slopes equal to or greater than 10%, use next higher Zone in Figure 8.06d to determine
apron length.
Apron length (ft)8Figure 8.06d
Determination of Stone Sizes For Dumped Stone Channel Linings and
Revetments
e
Max. stone size (in.)7Figure 8.06e
f
Min. & max range of stones (lbs)25-150Figure 8.05f
Weight range of 75% of stones (lbs)50-150Figure 8.05f

New York DOT Dissipator Method For Use in Defined Channels
Guide to Color Key:User Input DataCalculated ValueReference Data
Designed By:NLS Date:5.20.20
Checked By:SEB Date:5.20.20
Company:McGill Associates
Project Name:Horsepasture WWTP
Project No.:15.00391
Site Location (City/Town)Cashiers, NC
Culvert Id.Wetpond Spillway
Estimation of Stone Size and Dimensions For Culvert Aprons
Velocity (ft/s)10
Paved Channel Outlet
Opening type
Single or multiple openings?Single
(ft)
Outlet pipe diameter, D
15
o
NOTE 1: If opening type is anything other than "Pipe Culvert", D=A (Cross-
oo
sectional area of flow at outlet).
NOTE 2: If multiple openings, D=1.25 x D of single culvert.
oo
Zone5Figure 8.06c
Will apron have >/=10% grade?Yes
NOTE: For apron slopes equal to or greater than 10%, use next higher Zone in Figure 8.06d to determine
apron length.
Apron length (ft)75Figure 8.06d
Determination of Stone Sizes For Dumped Stone Channel Linings and
Revetments
e
Max. stone size (in.)23Figure 8.06e
f
Min. & max range of stones (lbs)25-800Figure 8.05f
Weight range of 75% of stones (lbs)200-800Figure 8.05f

New York DOT Dissipator Method For Use in Defined Channels
Guide to Color Key:User Input DataCalculated ValueReference Data
Designed By:NLC Date:5.29.20
Checked By:SEB Date:
Company:McGill Associates
Project Name:Horsepasture WWTP
Project No.:15.00391
Site Location (City/Town)Cashiers, NC
Culvert Id.Outlet Control Structure
Estimation of Stone Size and Dimensions For Culvert Aprons
Velocity (ft/s)7.65
Pipe Culvert
Opening type
Single or multiple openings?Single
(ft)
Outlet pipe diameter, D
2
o
NOTE 1: If opening type is anything other than "Pipe Culvert", D=A (Cross-
oo
sectional area of flow at outlet).
NOTE 2: If multiple openings, D=1.25 x D of single culvert.
oo
Zone2Figure 8.06c
Will apron have >/=10% grade?Yes
NOTE: For apron slopes equal to or greater than 10%, use next higher Zone in Figure 8.06d to determine
apron length.
Apron length (ft)8Figure 8.06d
Determination of Stone Sizes For Dumped Stone Channel Linings and
Revetments
e
Max. stone size (in.)8Figure 8.06e
f
Min. & max range of stones (lbs)25-150Figure 8.05f
Weight range of 75% of stones (lbs)50-150Figure 8.05f

New York DOT Dissipator Method For Use in Defined Channels
Guide to Color Key:User Input DataCalculated ValueReference Data
Designed By:NLC Date:7.2.20
Checked By:SEB Date:
Company:McGill Associates
Project Name:Horsepasture WWTP
Project No.:15.00391
Site Location (City/Town)Cashiers, NC
Culvert Id.Road A Ditch
Estimation of Stone Size and Dimensions For Culvert Aprons
Velocity (ft/s)2.94
Paved Channel Outlet
Opening type
Single or multiple openings?Single
(ft)
Outlet pipe diameter, D
2
o
NOTE 1: If opening type is anything other than "Pipe Culvert", D=A (Cross-
oo
sectional area of flow at outlet).
NOTE 2: If multiple openings, D=1.25 x D of single culvert.
oo
Zone1Figure 8.06c
Will apron have >/=10% grade?Yes
NOTE: For apron slopes equal to or greater than 10%, use next higher Zone in Figure 8.06d to determine
apron length.
Apron length (ft)6Figure 8.06d
Determination of Stone Sizes For Dumped Stone Channel Linings and
Revetments
e
Max. stone size (in.)2Figure 8.06e
f
Min. & max range of stones (lbs)25-150Figure 8.05f
Weight range of 75% of stones (lbs)50-150Figure 8.05f

New York DOT Dissipator Method For Use in Defined Channels
Guide to Color Key:User Input DataCalculated ValueReference Data
Designed By:NLC Date:8/6/2020
Checked By:SEB Date:
Company:McGill Associates
Project Name:Horsepasture WWTP
Project No.:15.00391
Site Location (City/Town)Cashiers, NC
Culvert Id.Permanent Ditch #1
Estimation of Stone Size and Dimensions For Culvert Aprons
Velocity (ft/s)9.02
Channel Outlet
Opening type
Single or multiple openings?Single
(ft)
Outlet pipe diameter, D
3
o
NOTE 1: If opening type is anything other than "Pipe Culvert", D=A (Cross-
oo
sectional area of flow at outlet).
NOTE 2: If multiple openings, D=1.25 x D of single culvert.
oo
Zone2Figure 8.06c
Will apron have >/=10% grade?Yes
NOTE: For apron slopes equal to or greater than 10%, use next higher Zone in Figure 8.06d to determine
apron length.
Apron length (ft)12Figure 8.06d
Determination of Stone Sizes For Dumped Stone Channel Linings and
Revetments
e
Max. stone size (in.)12Figure 8.06e
f
Min. & max range of stones (lbs)25-150Figure 8.05f
Weight range of 75% of stones (lbs)50-150Figure 8.05f

New York DOT Dissipator Method For Use in Defined Channels
Guide to Color Key:User Input DataCalculated ValueReference Data
Designed By:NLC Date:8/6/2020
Checked By:SEB Date:
Company:McGill Associates
Project Name:Horsepasture WWTP
Project No.:15.00391
Site Location (City/Town)Cashiers, NC
Culvert Id.Permanent Ditch #2
Estimation of Stone Size and Dimensions For Culvert Aprons
Velocity (ft/s)2.73
Channel Outlet
Opening type
Single or multiple openings?Single
(ft)
Outlet pipe diameter, D
3
o
NOTE 1: If opening type is anything other than "Pipe Culvert", D=A (Cross-
oo
sectional area of flow at outlet).
NOTE 2: If multiple openings, D=1.25 x D of single culvert.
oo
Zone1Figure 8.06c
Will apron have >/=10% grade?Yes
NOTE: For apron slopes equal to or greater than 10%, use next higher Zone in Figure 8.06d to determine
apron length.
Apron length (ft)9Figure 8.06d
Determination of Stone Sizes For Dumped Stone Channel Linings and
Revetments
e
Max. stone size (in.)2Figure 8.06e
f
Min. & max range of stones (lbs)25-150Figure 8.05f
Weight range of 75% of stones (lbs)50-150Figure 8.05f

New York DOT Dissipator Method For Use in Defined Channels
Guide to Color Key:User Input DataCalculated ValueReference Data
Designed By:NLC Date:8/6/2020
Checked By:SEB Date:
Company:McGill Associates
Project Name:Horsepasture WWTP
Project No.:15.00391
Site Location (City/Town)Cashiers, NC
Culvert Id.Permanent Ditch #3
Estimation of Stone Size and Dimensions For Culvert Aprons
Velocity (ft/s)2.38
Channel Outlet
Opening type
Single or multiple openings?Single
(ft)
Outlet pipe diameter, D
3
o
NOTE 1: If opening type is anything other than "Pipe Culvert", D=A (Cross-
oo
sectional area of flow at outlet).
NOTE 2: If multiple openings, D=1.25 x D of single culvert.
oo
Zone1Figure 8.06c
Will apron have >/=10% grade?Yes
NOTE: For apron slopes equal to or greater than 10%, use next higher Zone in Figure 8.06d to determine
apron length.
Apron length (ft)9Figure 8.06d
Determination of Stone Sizes For Dumped Stone Channel Linings and
Revetments
e
Max. stone size (in.)2Figure 8.06e
f
Min. & max range of stones (lbs)25-150Figure 8.05f
Weight range of 75% of stones (lbs)50-150Figure 8.05f

APPENDIX F
RAINFALL AND SOILS DATA

APPENDIX G
DRAINAGE AREA MAPS