SW3201003_Calculations_20201103

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YARBROUGH-WILLIAMS & HGULE, INC.
Planning • Surveying • Engineering
730 WINDSOR OAK COURT (28273)
P.O. BOX 7007 (28241)
CHARLOTTE, NC
PHONE [phone] FAX [phone]
NC CORPORATE REGISTRATION #C-0475
CALCULATIONS
AUTO FINANCE & CAR CARE CENTER
DATE:10/15/20
CONTENTS:
• STORM DRAINAGE CALCULATIONS
• DROP INLET CALCULATIONS
• EROSION SEDIMENT BASIN
CALCULATIONS
• SKIMMER CALCULATIONS
• SAND FILTER CALCULATIONS
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STORM DRAINAGE
CALCULATIONS

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DROP INLET
CALCULATIONS

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EROSION SEDIMENT
BASIN CALCULATIONS

AUTO FINANCE & CAR CARE CENTER
SEDIMENT BASIN CALCULATIONS
DATE: OCTOBER 15 2020 -
BASIN # 1 DRAINAGE AREA 5.16 AC
WKD
INTENSITY (I) 7.03 (10 yr)
Qio=CIA= 0.6 x 5.16 x 7.03 = 21.76 cfs
REQUIRED STORAGE _
UIRED SURFACE AREA
BASIN STORAGE DIMENSIONS
STORAGE PROVIDED -
TOP OF DAM HEIGHT (Y) =
Z — 3 +
SPILLWAY - L = Q / (3 x h15)
5.16 x 1800 = 9,288 CF
325 x Q10 = 7,074 SF
CONTOUR 688
CONTOUR 687
CONTOUR 686
19,412 CF 685
H + SPILLWAY DEPTH +1 .0' FREEBOARD
I + 1 = 5 FT
7,25 ft 20' MIN.
SURFACE AREA
7,966
6,938
5,967
5,052
TOTAL 19,413

SKIMMER
CALCULATIONS

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SAND FILTER
CALCULATIONS

SAND FILTER CALCULATIONS
references: NCDENR Stormwater BMP Manual Chapter 11
Date
7-Oct-20
PROJECT AUTO FINANCE & CAR CARE CENTER
SAND FILTER 1
Rama nw;%
730 Windsor Oak Ct
Charlotte, NO 28241
704-556-1990
YARBROUGH-WILLIAMS & HOULE, INC.
Planning - Surveying s Engineering
Site Area Post = Total Drainage Area (A) =
Site Area Pre = Total Drainage Area (A) =
Measured Impervious Area -
Hydrologic Data
Pre - ON
2.fi2 ac
4.86 aC.
4.86 8c
53 8596
Acrea a
Land Use
Soil T e
H r I i rou
CN
wei hted CN
005
Ex Pvmt
98
1 01
4.81
Woods
ScA
C
70
6928
0.00
000
486
Post - CN
CNP„
70
Acrea a
Land Use
Soil Type
H drolo is Grou
CN
(weighted) CN
262
Bld /Pvt/SW
98
52.77
2.24
Grass
SCA
C
74
34.15
000
0.00
4.66
Pre
CN 70
Post
87
CNP,,,
87
Steps 1, 2 Determine if the development site and conditions are appropriate for the use of a
Sand Filter pond and consider any site -specific design considerations.
Step 3 Compute Water Quality Volume (WQv)
Compute Runoff Coefficient, Rv, using (Schueler's Method) Equation 3,1
Rv = 0.05 + 0.009 (1) 1 = percent impervious over basin area = 618 %
Total Rainfall amount (P) _ =in
Rv = 0534618916 RE) = 4
Compute Water Quality Volume, WQv, using Equation 3.2
Design Volume
WQv = 1.0RvA/12 = 0.22 ac-ft or 9432 cf
Convert Water Quality Volume, WQv to inches of runoff using Equation 3.3
WQv = 1 0(Rv) = 0.53 in

Compute Site Hydrologic Input Parameters
Using SCS hydrologic procedures and/or computer models the following data can
be determined for the example development site.
Step 4 Summary of Hydrocad Input and Output
HYDROLOGIC INPUT DATA
Condition
Area ac
CN
tc hours
tc min
Pre-dev
4.86
70
0.08
5
Post dev
4.86
87
0.08
5
Results of Preliminary Hydrologic Calculations
(From Computer Model Results Using SCS Hydrologic Procedures)
Condition
1 YR
Q2- ear
Q10- ear
Runoff
cfs
cfs
cfs
Pre-Dev
3.22
3.27
11.12
w/ out controls
Post Dev
10.04
12.64
1
23.27
w/ controls
Post Dev
0.47
0.73
9.58
POST MODIFIED CN
Step 5 Compute Water Quality Peak Flow (WQp) using modified CN (adjusted) value
Compute modified SCS curve number, CN, using Equation 3.4
CN mod -post = 1000/[10 + 5P + 10WQv — 10(WQV2 + 1 25 WQVP)0 51
CN mod -post = 95
Compute WQp using SCS the hydrograph procedure documented in the CMSWDM
using Hydrocad hydrologic model, A 1-inch, 6-hour balanced storm event is required.
See Hydrocad Report WQp = 6.48 cfs
Step 5 Compute Sedimentation Chamber Minimum Surface Area
Per Section 11.3.5 NCDENR Stormwater BMP Manual
Also Min As (ftz) = [240 " Rv " AD] . Ro (fe) = 623.58 sf
As provided = 1850.0 sf
Forebay Chamber Storaga-El ovation Data
Elevation
Area sf
Area ac
Ht ft
Inc. Vol ac-ft
Acc. Vol ac-ft
Acc. Vol cf
685
1000.0
0.023
0.0
0,00
000
000
686
1400.0
0.032
1.0
0,03
003
120000
687
1850.0
0.042
2.0
1.00
1.03
44760 00

Step 6 Compute Sand Filter Area to Treat Water Quality Volume
Af = (WQv)(df)/[(k)(hf+df)(tf)j
where:
Af = surface area of filter bed (ft2)
WQv = Treatment Water Quality Volume (cf)
9431.64 cf
df = filter bed depth (ft)
1.50
k = coefficient of permeability of filter media (ft/day)
3.5
hA = average height of water above filter bed (ft)
0.96
tf = design filter bed drain time (days)
1.67
Af = 981.9
sf required min area of sand filter
Est. Sand filter area 31.3
foot by 31.3
Filter Surface Area (At= )
982 Isf for calculations
NOTE: top sand filter provided is 43' X 43'
bottom of sand filter (41' X 41) is used to calculate outflow through the filter
Actual Sand Surface Area Provided =
1000 Isf
Step 7 Verify the Volumes
[Af (sf) + As (sf)] x hMaxriiter = 26220 sf >_
Filter area provided = 5500 sf
Forebay area provided = 1400 sf
hMaxriiter= 3.80 ft max head interpolated
34500
Step 8 Develop Water Quality Storage -Elevation Table 4100.0
485000
Water Qualitv Storage -Elevation Data fincludino Fornhavl
9432
40 hrs
sf minimum
Elevation
Area sf
Area ac
Ht ft
Inc. Vol ac-ft
Acc. Vol ac-ft
Acc. Vol c
6845
1000.0
0.023
000
0.00
0.00
0.00
685
4450.0
0102
0.50
0.03
0.03
1362.50
686
5500.0
0.126
1.50
0.11
0.15
6337.50
687
6700,00
0 154
2.50
0.14
029
12437.50
688
7950.00
0183
3.50
0.17
0.45
19762.50
689
9050.00
0.208
4.50
0.20
065
28262.50
690
10150.00
0233
5.50
0.22
0.87
37862.50
Top of Sand Filter Elevation
684.50
100 yr WSE
688.65
WQv Elevation =
686.43
WQv Required =
9431 6
cf
0.217
ac-ft per sand filter
WQv treated =
944001
cf
0.217
ac-ft per sand filter
Forebay Weir Elevation =
687
Top of Box Weir Elevation =
688.30
WQv release in (max 40 hrs) = I YES !

Step 9 Develop Stage -Discharge for Sand Filter Media
Af = (WQv)(df)/[(k)(hf+dfl(tf)1
WQv/tf = Qo = Af (k)(hf+df)/(df))
where:
Af = surface area of filter bed provided (ft2)
df = filter bed depth (ft)
k = coefficient of permeability of filter media (ft/day)
hA = average height of water above filter bed (ft)
At Elevation 687 2.5 Feet above sand filler
Qo = 9383 coda
0.108 cfs
At Elevation 686 1.5 feet above sand filter
Qo = 7000 cf/da
0.081 I I cfs
At Elevation 685 0.5 feet above sand filter
Qo = 4667 coda
0 054 cfs
At Elevation 684.5 sand filter surface
Qo = 0 cf/da
0.000 I I cfs
Bottom of Sand Filter Elevation = 1 682.00.
Time to Drain WQV through sand filter = 40 hr
SHWT elevation = 0
1000.00 sf
1.50 ft
3.5
0.96 fl

Step 10 Design Underdrain System
The underdrain capacity must be greater than the filter media capacity.
The capacity must drain the runoff volume from the system within design duration of 40 hours.
The design must assume that 50 percent of the underdrain system (perforations and pipe system capacity)
is lost due to clogging.
Design specifications require the underdrain system to be a 8-inch perforated PVC pipe with 3/8-inch
perforations spaced 3 inches on center, along 4 longitudinal rows spaced 90 apart. Minimum underdrain
slope is 0.5 percent
Sand Filter Area = 981.92 sf
The filter media is the controlling outflow condition.
Compute minimum drawdown discharge
Water Quality Volume =
Drawdown =
Compute Performation Capacity
The maximum underdrain spacing is 10 feet on center
The dimension of the sand filter bottom is
Actual length of pipe containing holes is 29 feet.
Number of perforations =
50 percent of perforations =
Capacity of one hole = CA(2gh)05
Total Capacity
Filter Media Capacity =
Total Capacity of
Compute underdrain pipe capacity
9431.64 cf
9431.64 cf /(120 hrs)(3600 sec/hour)
0.022 cfs
33'x33'
1( pipe)(3 rows)((29) ft/pipe)(4 holes/ft)
3481 holes
174 holes
-(0.6)(3.1416)[(3/8in)(1/24)]2[(64.4)(5 0ft)]05
0.0083 cfs
= 0.083 x 174
= 1.44 cfs
0.068 cfs at 1 foot of head
1.44 cfs is greater than Filter Media Capacity and
Minimum Drawdown Discharge
Underdrain Pipe Size = © in = Area=
For 6-inch PVC underdrain pipe at 0,005 ft/ft slope:
Capacity of pipe = (1.49/n)(A)(A/P)061(S)05
_ =(1 49/0.013)(0.196)(0,125)0'67(0.005)0.5
= 0,39 cfs
Fifty percent assuming clogging = 0.20 cfs
The underdrain pipe capacity (0.20 cfs) is greater than the filter media capacity of 0 068 cfs,
and greater than the minimum drawdown capacity requirement (0.020 cfs computed in this step) Therefore
the design is acceptable.
Step 11 Design Overflow Weir
A 16 foot emergency spillway overflow weir is designed with a weir elevation of 688 3 design elevation
Step 12 Access Maintenance Access and Safety Features
All areas of both chambers must be within 25 feet of an access location from the surface that is large enough
for personnel to enter in order to remove trash, debris, sediment, etc
In addition, the sand filter media must be accessible in order to facilitate complete replacement when the
sand filter ponds runoff without filtration
Check 50 year storm elevation - The 50 year storm events bypass the sand filters. The partial flow
from these storms flowing to the sand filter stays within the sand filters with overflow over the outlet structure.
0.196 sf
0.125

Pre-dev
Subcat Reach on Link

Sf # 1 HydroCad
Prepared by Yarbrough -Williams & Houle, Inc. Printed 10/14/2020
HvdroCAD®10.10-4a s/n 05047 ©2020 HvdroCAD Software Solutions LLC Page 2
Rainfall Events Listing (selected events)
Event#
Event
Storm Type
Curve Mode
Duration
B/B
Depth
AMC
Name
(hours)
(inches)
1
1 yr
Charlotte 24-hr 1-yr
Default
24.00
1
2.58
2
2
2-yr
Charlotte 6-hr
2-yr Default
6.00
1
2.28
2
3
10-yr
Charlotte 6-hr
10-yr Default
6.00
1
3.72
2

Sf # 1 HydroCad Charlotte 24-hr 1-yr 1 yr Rainfall=2.58"
Prepared by Yarbrough -Williams & Houle, Inc. Printed 10/14/2020
HydroCADO 10.10-4a s/n 05047 © 2020 HydroCAD Software Solutions LLC Paae 3
Summary for Subcatchment 7S: Pre-dev
Runoff = 3.22 cfs @ 12.04 hrs, Volume= 0.200 af, Depth= 0.49"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-140.00 hrs, dt= 0.01 hrs
Charlotte 24-hr 1-yr 1 yr Rainfall=2.58"
Area ac CN Description
4.860 70 Woods, Good. HSG C
4.860 100.00% Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) ft/ft) (ft/sec) (cfs
5.0 Direct Entry, Direct Entry
Subcatchment 7S: Pre-dev
Hydrograph
Charlotte 24-hr 1-yr
3
1 yr: Rainfall=2.58"
Runoff Area=4:860 ac
Runoff Volume=0.200 of
Runoff Depth=0.49''
LL
Tc=5.0 min
CN=70
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Time (hours)
U Runoff

Sf # 1 HydroCad Charlotte 6-hr 2-yr Rainfall=2.28"
Prepared by Yarbrough -Williams & Houle, Inc. Printed 10/14/2020
HvdroCAD® 10.10-4a s/n 05047 © 2020 HvdroCAD Software Solutions LLC Paae 4
Summary for Subcatchment 7S: Pre-dev
Runoff = 3.27 cfs @ 3.18 hrs, Volume= 0.144 af, Depth= 0.35"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-140.00 hrs, dt= 0.01 hrs
Charlotte 6-hr 2-yr Rainfall=2.28"
Area (ac) CN Description
4.860 70 Woods, Good.. HSG C
4.860 100.00% Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) ft/ft) ft/sec cfs
5.0 Direct Entry, Direct Entry
Subcatchment 7S: Pre-dev
Hydrograph
6-
Charlotte:Sdhr 2-yr
3 Rainfall=2.28"
Runoff Area--4.860 ac
Runoff Volume=0.144 of
Runoff :Depth=0.35
LL Tc=5.0 m i n
CN-70
1 5 10 15 20 25 30 35 1 45 50 55 .1 65 70 75 81 85 91 95 100 105 110 115 120 125 130 135 140
C! Runoff

Sf # 1 HydroCad Charlotte 6-hr 10-yr Rainfall=3.72"
Prepared by Yarbrough -Williams & Houle, Inc. Printed 10/14/2020
HvdroCAD®10.10-4a s/n 05O47 ©2020 H droCAD Software Solutions LLC Pa e 5
Summary for Subcatchment 7S: Pre-dev
Runoff = 11.12 cfs @ 3.16 hrs, Volume= 0.464 af, Depth= 1.15"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-140.00 hrs, dt= 0.01 hrs
Charlotte 6-hr 10-yr Rainfall=3.72"
Area ac CN Description
4.860 70 Woods, Good, HSG C
4.860 100.00% Pervious Area
Tc Length Slope Velocity Capacity Description
min feet ft/ft ft/sec) (cfs)
5.0 Direct Entry, Direct Entry
Subcatchment 7S: Pre-dev
Hydrograph
12
i2 cfs
Charlotte 67hr 10-yr
10 Rainfall=3.72"
Runoff Area=4860 ac
Runoff Volume=0.464 of
Runoff 'Depth=1.15"
e Tc=5.0 min
U.
CN=70
4
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15 10 15 20 25 30 35 41 45 50 55 61 65 70 75 :1 85 91 95 100 105 110 115 120 125 130 135 140
Runoff

Sf # 1 HydroCad Table of Contents
Prepared by Yarbrough -Williams & Houle, Inc. Printed 10/14/2020
HvdroCAD®10.10-4a s/n 05047 ©2020 HvdroCAD Software Solutions LLC
TABLE OF CONTENTS
Protect Reports
1 Routing Diagram
2 Rainfall Events Listing (selected events)
1 yr Event
3 Subcat 7S: Pre-dev
2-yr Event
4 Subcat 7S: Pre-dev
10-yr Event
5 Subcat 7S: Pre-dev

8s) � 6�
Post Development 1 in
w/ Mod CN
n�
Subcat) Reach. Pon4.. Link
Sand Filter

Sf # 1 HydroCad
Prepared by Yarbrough -Williams & Houle, Inc. Printed 10/14/2020
HydroCAD®10.10-4a s/n 05047 ©2020 HydroCAD Software Solutions LLC Page 2
Rainfall Events Listing (selected events)
Event# Event Storm Type Curve Mode Duration B/B Depth AMC
Name (hours) (inches)
1 1 inch Charlotte 6-hr 1 INCH Default 6.00 1 1.00 2

Sf # 1 HydroCad Charlotte 6-hr 1 INCH 1 inch Rainfall=1.00"
Prepared by Yarbrough -Williams & Houle, Inc. Printed 10/14/2020
HvdroCAD® 10 10-4a s/n 05047 © 2020 H droCAD Software Solutions LLC Page 3
Summary for Subcatchment 8S: Post Development 1 in w / Mod CN
Runoff = 6.48 cfs @ 3.11 hrs, Volume= 0.228 af, Depth= 0.56"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-140.00 hrs, dt= 0.01 hrs
Charlotte 6-hr 1 INCH 1 inch Rainfall=1.00"
Area (ac) CN Description
4.860 95 post dev
4.860 100.00% Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) ft/ft (ft/sec) cfs
5.0 Direct Entry, Post Dev
Subcatchment 8S: Post Development 1 in w / Mod CN
Hydrograph
'.1
Charlotte 6-hr
1 INCH
1 inch Rainfall=1.00"
Runoff Area-4.860 ac
Runoff Volume=0.228 of
Runoff Depth=0.56
Tc=5.0 min
CN=95
1 5 10 15 20 25 30 35 41 45 50 55 61 65 70 75 81 85 90 95 100 105 110 115 120 125 130 135 140
ED Runoff

Sf # 1 HydroCad Charlotte 6-hr 1 INCH 1 inch Rainfall=1.00"
Prepared by Yarbrough -Williams & Houle, Inc. Printed 10/14/2020
HydroCAD® 10.10-4a s/n 05047 ©2020 HydroCAD Software Solutions LLC Pape 4
Summary for Pond 26P: Sand Filter
Inflow Area = 4.860 ac, 0.00% Impervious, Inflow Depth = 0.56" for 1 inch event
Inflow = 6.48 cfs @ 3.11 hrs, Volume= 0.228 of
Outflow = 0.09 cfs @ 6.02 hrs, Volume= 0.228 af, Atten= 99%, Lag= 174.6 min
Primary = 0.09 cfs @ 6.02 hrs, Volume= 0.228 of
Routing by Stor-Ind method, Time Span= 0.00-140.00 hrs, dt= 0.01 hrs / 2
Peak Elev= 686.43' @ 6.02 hrs Surf.Area= 6,013 sf Storage= 8,944 cf
Plug -Flow detention time= 1,047.6 min calculated for 0.228 of (100% of inflow)
Center -of -Mass det. time= 1,047.9 min ( 1,257.6 - 209.7 )
Volume' Invert
#1 684.50'
Avail.Storape Storage Descri
37,863 cf Custom Stage Data (Prismatic) Listed below
Elevation
Surf.Area
Inc.Store Cum.Store
feet
(sq-ft)
(cubic -feet) (cubic -feet)
684.50
1,000
0 0
685.00
4,450
1,363 1,363
686.00
5,500
4,975 6,338
687.00
6,700
6,100 12,438
688.00
7,950
7,325 19,763
689.00
9,050
8,500 28,263
690.00
10,150
9,600 37,863
Device Routing
Invert
Outlet Devices
#1 Primary
683.24'
24.0" Round Culvert L= 59.0' Ke= 0.500
Inlet / Outlet Invert= 683.24' / 682.91' S= 0.0056 '/' Cc= 0.900
n= 0.012, Flow Area= 3.14 sf
#2 Device 1
684.50'
Special & User -Defined
Head (feet) 0.00 0.50 1.50 2.50
Disch. (cfs) 0.000 0.054 0.081 0.108
#3 Device 1
687.30'
4.0' long Sharp -Crested Rectangular Weir 2 End Contraction(s)
#4 Device 1
688.30'
16.0' long Sharp -Crested Rectangular Weir 2 End Contraction(s)
Primary OutFlow Max=0.09 cfs @ 6.02 hrs HW=686.43' (Free Discharge)
'�-1=Culvert (Passes 0.09 cfs of 21.30 cfs potential flow)
2=Special & User -Defined (Custom Controls 0.09 cfs)
3=Sharp-Crested Rectangular Weir ( Controls 0.00 cfs)
=Sharp -Crested Rectangular Weir ( Controls 0.00 cfs)

Sf # 1 HydroCad Charlotte 6-hr 1 INCH 1 inch Rainfall=1.00"
Prepared by Yarbrough -Williams & Houle, Inc. Printed 10/14/2020
HydroCAD®10.10-4a s/n 05047 ©2020 HydroCAD Software Solutions LLC Paae 5
Pond 26P: Sand Filter
Hydrograph
Inflow Area=4.8:60 ac
g Peak E l ev=686.43'
5 Storage=8,944 cf
w 4
u
3
0
LL
3
2
is r�s
Q
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 160 165 110 115 120125130135140
Time (hours)
E: Inflow
p Primary

Sf # 1 HydroCad Table of Contents
Prepared by Yarbrough -Williams & Houle, Inc. Printed 10/14/2020
HydroCAD®10.10-4a s/n 05047 ©2020 HvdroCAD Software Solutions LLC
TABLE OF CONTENTS
Project Reports
1 Routing Diagram
2 Rainfall Events Listing (selected events)
1 inch Event
3 Subcat 8S: Post Development 1 in w / Mod CN
4 Pond 26P: Sand Filter

9S ) �
Post Development
Subcat Reach on [Link
Sand Filter

Sf # 1 HydroCad
Prepared by Yarbrough -Williams & Houle, Inc. Printed 10/14/2020
H droCAD®10.10-4a s/n 05047 ©2020 H droCAD Software Solutions LLC Page 2
Rainfall Events Listing (selected events)
Event# Event Storm Type Curve Mode Duration B/B Depth AMC
Name (hours) (inches)
1 1 yr
Charlotte 24-hr 1-yr
Default
24.00
1
2.58 2
2 2-yr
Charlotte 6-hr 2-yr
Default
6.00
1
2.28 2
3 10-yr
Charlotte 6-hr 10-yr
Default
6.00
1
3.72 2
4 50 yr
Charlotte 6-hr 50-yr
Default
6.00
1
4.92 2
5 100 YEAR
Charlotte 6-hr 100-yr
Default
6.00
1
5.34 2

Sf # 1 HydroCad Charlotte 24-hr 1-yr 1 yr Rainfall=2.58"
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Summary for Subcatchment 9S: Post Development
Runoff = 10.04 cfs @ 11.99 hrs, Volume= 0.558 af, Depth= 1.38"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-140.00 hrs, dt= 0.01 hrs
Charlotte 24-hr 1-yr 1 yr Rainfall=2.58"
Area (ac) CN Description
2.620 98 Paved parking, HSG C
2.240 74 >75% Grass cover, Good, HSG C
4.860 87 Weighted Average
2.240 46.09% Pervious Area
2.620 53.91% Impervious Area
Tc Length Slope Velocity Capacity Description
min (feet) ft/ft) (ft/sec) (cfs)_
5.0 Direct Entry, Post Dev
11
8
[ •o C14 Cry ]
Subcatchment 9S: Post Development
Hydrograph
Charlotte 24-hr 1-yr
1 yr Rainfall=2.58','
Runoff Area=4.860:ac
Runoff Volume=0.558 of
Runoff Depth=1.38
Tc=5.0 m i n
CN=87
i sr -.--ter- - --
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 135 140
�E Runoff

Sf # 1 HydroCad Charlotte 24-hr 1-yr 1 yr Rainfall=2.58"
Prepared by Yarbrough -Williams & Houle, Inc. Printed 10/14/2020
HydroCADO 10.10-4a s/n 05047 © 2020 HvdroCAD Software Solutions LLC Paoe 4
Summary for Pond 27P: Sand Filter
Inflow Area = 4.860 ac, 53.91 % Impervious, Inflow Depth = 1.38" for 1 yr event
Inflow = 10.04 cfs @ 11.99 hrs, Volume= 0.558 of
Outflow = 0.47 cfs @ 13.63 hrs, Volume= 0.558 af, Atten= 95%, Lag= 98.5 min
Primary = 0.47 cfs @ 13.63 hrs, Volume= 0.558 of
Routing by Stor-Ind method, Time Span= 0.00-140.00 hrs, dt= 0.01 hrs / 2
Peak Elev= 687.39' @ 13.63 hrs Surf.Area= 7,187 sf Storage= 15,290 cf
Plug -Flow detention time= 1,263.0 min calculated for 0.558 of (100% of inflow)
Center -of -Mass det. time= 1,263.4 min (2,090.0 - 826.7 )
Volume Invert
Avail.Stora a Storage Description
#1 684.50'
37,863 cf Custom Stage Data (Prismatic) Listed below
Elevation Surf.Area
Inc.Store Cum.Store
(feet)
(sq-ft)
(cubic -feet) (cubic -feet)
684.50
1,000
0 0
685.00
4,450
1,363 1,363
686.00
5,500
4,975 6,338
687.00
6,700
6,100 12,438
688.00
7,950
7,325 19,763
689.00
9,050
8,500 28,263
690.00
10,150
9,600 37,863
Device Routing
Invert
Outlet Devices
#1 Primary
683.24'
24.0" Round Culvert L= 55.0' Ke= 0.500
Inlet / Outlet Invert= 683.24' / 682.91' S= 0.0060 '/' Cc= 0.900
n= 0.012, Flow Area= 3.14 sf
#2 Device 1
684.50'
Special & User -Defined
Head (feet) 0.00 0.50 1.50 2.50
Disch. (cfs) 0.000 0.054 0.081 0.108
#3 Device 1
687.30'
4.0' long Sharp -Crested Rectangular Weir 2 End Contraction(s)
#4 Device 1
688.30'
16.0' long Sharp -Crested Rectangular Weir 2 End Contraction(s)
Primary OutFlow Max=0.46 cfs @ 13.63 hrs HW=687.39' (Free Discharge)
L =Culvert (Passes 0.46 cfs of 26.84 cfs potential flow)
2=Special & User -Defined (Custom Controls 0.11 cfs)
3=Sharp-Crested Rectangular Weir (Weir Controls 0.35 cfs @ 0.98 fps)
-Sharp-Crested Rectangular Weir ( Controls 0.00 cfs)

Sf # 1 HydroCad Charlotte 24-hr 1-yr 1 yrRainfall=2.58"
Prepared by Yarbrough -Williams & Houle, Inc. Printed 10/14/2020
H droCADO 10 10-4a s/n 05047 © 2020 H droCAD Software Solutions LLC Page 5
Pond 27P: Sand Filter
Hydrograph
I I Inflow
q Primary
7
N
w 6
O
LL "
1
3
•. �047 •:�y
Inflow Area=4.860 ac
Peak Elev=687.39'
Storage=15,29'0 cf
0
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100105110115120125130135140
Time (hours)

Sf # 1 HydroCad Charlotte 6-hr 2-yr Rainfall=2.28"
Prepared by Yarbrough -Williams & Houle, Inc. Printed 10/14/2020
HvdroCADO 10.10-4a s/n 05047 © 2020 HydroCA❑ Software Solutions LLC Page 6
Summary for Subcatchment 9S: Post Development
Runoff = 12.64 cfs @ 3.16 hrs, Volume= 0.457 af, Depth= 1.13"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-140.00 hrs, dt= 0.01 hrs
Charlotte 6-hr 2-yr Rainfall=2.28"
Area (ac) CN Description
2.620
98 Paved parking, HSG C
2.240
74 >75% Grass cover, Good, HSG C
4.860
87 Weighted Average
2.240
46.09% Pervious Area
2.620
53.91% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) feet ft/ft(ft/sec) (cfs)
5.0 Direct Entry, Post Dev
Subcatchment 9S: Post Development
Hydrograph
14
1 1«.Gh Cfe
12 Charlotte 6-hr 2-yr
11 Rainfall=2.28"
10 Runoff Area=4.860 ac
9 Runoff Volume=0.457 of
7 Runoff Depth=1.13'
7
LL 6 Tc=5.0 min
CN= 87
3
2
1
0
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 135 140
Time (hours)
1 Runoff

Sf # 1 HydroCad Charlotte 6-hr 2-yr Rainfall=2.28"
Prepared by Yarbrough -Williams & Houle, Inc. Printed 10/14/2020
HydroCADO 10.10-4a s/n_ 05047 © 2020 HydroCAD Software Solutions LLC Page 7
Summary for Pond 27P: Sand Filter
Inflow Area = 4.860 ac, 53.91% Impervious, Inflow Depth = 1.13" for 2-yr event
Inflow = 12.64 cfs @ 3.16 hrs, Volume= 0.457 of
Outflow = 0.73 cfs @ 4.44 hrs, Volume= 0.457 af, Atten= 94%, Lag= 77.1 min
Primary = 0.73 cfs @ 4.44 hrs, Volume= 0.457 of
Routing by Stor-Ind method, Time Span= 0.00-140.00 hrs, dt= 0.01 hrs / 2
Peak Elev= 687.43' @ 4.44 hrs Surf.Area= 7,238 sf Storage= 15,589 cf
Plug -Flow detention time= 1,157.2 min calculated for 0.457 of (100% of inflow)
Center -of -Mass det. time= 1,157.5 min ( 1,372.4 - 214.9 )
Volume
Invert Avail.Stora a Storage
Description
#1
684.50'
37,863 cf Custom Stage Data (Prismatic) Listed below
Elevation
Surf.Area
Inc.Store
Cum.Store
(feet)
s -ft
(cubic -feet)
(cubic -feet
684.50
1,000
0
0
685.00
4,450
1,363
1,363
686.00
5,500
4,975
6,338
687.00
6,700
6,100
12,438
688.00
7,950
7,325
19,763
689.00
9,050
8,500
28,263
690.00
10,150
9,600
37,863
Device Routinq Invert Outlet Devices
#1
Primary
683.24'
24.0" Round Culvert L= 55.0' Ke= 0.500
Inlet / Outlet Invert= 683.24' / 682.91' S= 0.00607' Cc= 0.900
n= 0.012, Flow Area= 3.14 sf
#2
Device 1
684.50'
Special & User -Defined
Head (feet) 0.00 0.50 1.50 2.50
Disch. (cfs) 0.000 0.054 0.081 0.108
#3
Device 1
687.30'
4.0' long Sharp -Crested Rectangular Weir 2 End Contraction(s)
#4
Device 1
688.30'
16.0' long Sharp -Crested Rectangular Weir 2 End Contraction(s)
Primary OutFlow Max=0.72 cfs @ 4.44 hrs HW=687.43' (Free Discharge)
't- =Culvert (Passes 0.72 cfs of 27.02 cfs potential flow)
2=Special & User -Defined (Custom Controls 0.11 cfs)
3=Sharp-Crested Rectangular Weir (Weir Controls 0.61 cfs @ 1.18 fps)
=Sharp -Crested Rectangular Weir ( Controls 0.00 cfs)

Sf # 1 HydroCad Charlotte 6-hr 2-yr Rainfall=2.28"
Prepared by Yarbrough -Williams & Houle, Inc. Printed 10/14/2020
HydroCAD®10.10-4a s/n 05047 ©2020 HydroCAD Software Solutions LLC Paae 8
Pond 27P: Sand Filter
Hydrograph
14 +&a cfs l
i3 Inflow Area=4.860 ac
12 11 Peak Elev=687.43'
10 Storage=15,589 �cf
9
w 8
u
3 7
0
LL 6
5
!.
3
2
0 73 d.
1
Q .. ..
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 BS 90 95 100105110115120125130135140
Time (hours)
F11—in—flow,vi
CI Primary

Sf # 1 HydroCad Charlotte 6-hr 10-yr Rainfall=3.72"
Prepared by Yarbrough -Williams & Houle, Inc. Printed 10/14/2020
HydroCAD®10.10-4a s/n 05047 ©2020 HydroCAD Software Solutions LLC Paae 9
Summary for Subcatchment 9S: Post Development
Runoff = 23.27 cfs @ 3.15 hrs, Volume= 0.964 af, Depth= 2.38"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-140.00 hrs, dt= 0.01 hrs
Charlotte 6-hr 10-yr Rainfall=3.72"
Area (ac) CN Description
2.620 98 Paved parking, HSG C
2.240 74 >75% Grass cover. Good. HSG C
4.860 87 Weighted Average
2.240 46.09% Pervious Area
2.620 53.91% Impervious Area
Tc Length Slope Velocity Capacity Description
min feet ft/ftft/sec) (cfs
5.0 Direct Entry, Post Dev
Subcatchment 9S: Post Development
Hydrograph
26
25
2 23.?.7 d;
23 Charlotte 6-hr 10,-yr
22
20 Rainfall=3.72�'
18 Runoff Area=4860 ac
16 Runoff Volume=0.964 of
14 Runoff 'Depth=2.38"
3 13
° 12 Tc=5.0 m i n
a 11
10
CN=87
8
7
6
5
4
3
8
1
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 135 140
Time (hours)
r] Runoff

Sf # 1 HydroCad Charlotte 6-hr 10-yr Rainfall=3.72"
Prepared by Yarbrough -Williams & Houle, Inc. Printed 10/14/2020
HydroCADO 10 10-4a s/n 05047 © 2020 HydroCAD Software Solutions LLC Page 10
Summary for Pond 27P: Sand Filter
Inflow Area = 4.860 ac, 53.91 % Impervious, Inflow Depth = 2.38" for 10-yr event
Inflow = 23.27 cfs @ 3.15 hrs, Volume= 0.964 of
Outflow = 9.58 cfs @ 3.32 hrs, Volume= 0.964 af, Atten= 59%, Lag= 10.1 min
Primary = 9.58 cfs @ 3.32 hrs, Volume= 0.964 of
Routing by Stor-Ind method, Time Span= 0.00-140.00 hrs, dt= 0.01 hrs / 2
Peak Elev= 688.13' @ 3.32 hrs Surf.Area= 8,093 sf Storage= 20,864 cf
Plug -Flow detention time= 564.8 min calculated for 0.964 of (100% of inflow)
Center -of -Mass det. time= 565.2 min ( 774.4 - 209.2 )
Volume Invert
Avail.Stora a Storage Description
#1 684.50'
37,863 cf Custom Stage Data (Prismatic) Listed below
Elevation Surf.Area
Inc.Store Cum.Store
feet
s -ft
(cubic -feet) cubic -feet)
684.50
1,000
0 0
685.00
4,450
1,363 1,363
686.00
5,500
4,975 6,338
687.00
6,700
6,100 12,438
688.00
7,950
7,325 19,763
689.00
9,050
8,500 28,263
690.00
10,150
9,600 37,863
Device Routing
Invert
Outlet Devices
#1 Primary
683.24'
24.0" Round Culvert L= 55.0' Ke= 0.500
Inlet / Outlet Invert= 683.24' / 682.91' S= 0.0060'/' Cc= 0.900
n= 0.012, Flow Area= 3.14 sf
#2 Device 1
684.50'
Special & User -Defined
Head (feet) 0.00 0.50 1.50 2.50
Disch. (cfs) 0.000 0.054 0.081 0.108
#3 Device 1
687.30'
4.0' long Sharp -Crested Rectangular Weir 2 End Contraction(s)
#4 Device 1
688.30'
16.0' long Sharp -Crested Rectangular Weir 2 End Contraction(s)
Primary OutFlow Max=9.58 cfs @ 3.32 hrs HW=688.13' (Free Discharge)
L1=Culvert (Passes 9.58 cfs of 29.83 cfs potential flow)
Z=Special & User -Defined (Custom Controls 0.11 cfs)
3=Sharp-Crested Rectangular Weir (Weir Controls 9.47 cfs @ 2.98 fps)
=Sharp -Crested Rectangular Weir ( Controls 0.00 cfs)

Sf # 1 HydroCad Charlotte 6-hr 10-yr Rainfall=3.72"
Prepared by Yarbrough -Williams & Houle, Inc. Printed 10/14/2020
HydroCAD®10.10-4a s/n 05047 ©2020 HydroCAD Software Solutions LLC Paae 11
Pond 27P: Sand Filter
Hydrograph
2.6
24 Inflow Area=4.860 ac
22 Peak Elev=688.13'
20:
1s Storage=203864 .d
16-
T
u W.
0 12
LL
asa di.
ta-
8..`
?.
0
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 BS 90 95 100105110115120125130135140
Time (hours)
LI Inflow
L"] Primary

Sf # 1 HydroCad Charlotte 6-hr 50-yr 50 yr Rainfall=4.92"
Prepared by Yarbrough -Williams & Houle, Inc. Printed 10/14/2020
HvdroCADO 10.10-4a s/n 05047 ©2020 HydroCAD Software Solutions LLC Paae 12
Summary for Subcatchment 9S: Post Development
Runoff = 32.67 cfs @ 3.11 hrs, Volume= 1.414 af, Depth= 3.49"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-140.00 hrs, dt= 0.01 hrs
Charlotte 6-hr 50-yr 50 yr Rainfall=4.92"
Area (ac) CN Description
2.620
98 Paved parking, HSG C
2.240
74 >75% Grass cover, Good, HSG C
4.860
87 Weighted Average
2.240
46.09% Pervious Area
2.620
53.91% Impervious Area
Tc Length Slope Velocity Capacity Description
min feet ft/ft) (ft/sec) (cfs
5.0 Direct Entry, Post Dev
36
32
30
28
26
24
22
20
18
0
LL 16
14
12
10
8
6
4
2
0
0
Subcatchment 9S: Post Development
Hydrograph
Charlotte 6-hr
50'-yr
50 yr Rainfall=4.92�'
Runoff Area=4.860 ac
Runoff Volume=1.414 of
Runoff Depth=3.49
Tc=5.0 m i n
CN=87
5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 135 140
Time (hours)
�❑ Runoff

Sf # 1 HydroCad Charlotte 6-hr 50-yr 50 yr Rainfall=4.92"
Prepared by Yarbrough -Williams & Houle, Inc. Printed 10/14/2020
H droCAD®10.10-4a s/n 05047 ©2020 H droCAD Software Solutions LLC Page 13
Summary for Pond 27P: Sand Filter
Inflow Area = 4.860 ac, 53.91 % Impervious, Inflow Depth = 3.49" for 50 yr event
Inflow = 32.67 cfs @ 3.11 hrs, Volume= 1.414 of
Outflow = 23.91 cfs @ 3.18 hrs, Volume= 1.414 af, Atten= 27%, Lag= 4.3 min
Primary = 23.91 cfs @ 3.18 hrs, Volume= 1.414 of
Routing by Stor-Ind method, Time Span= 0.00-140.00 hrs, dt= 0.01 hrs / 2
Peak Elev= 688.55' @ 3.18 hrs Surf.Area= 8,557 sf Storage= 24,454 cf
Plug -Flow detention time= 391.7 min calculated for 1.414 of (100% of inflow)
Center -of -Mass det. time= 392.1 min ( 596.8 - 204.7 )
Volume Invert
#1 684.50'
Avail.Storage Storaqe Descri
37,863 cf Custom Stage Data (Prismatic) Listed below
Elevation
Surf.Area
Inc.Store Cum.Store
(feet)
s -ft)
cubic -feet cubic -feet
684.50
1,000
0 0
685.00
4,450
1,363 1,363
686.00
5,500
4,975 6,338
687.00
6,700
6,100 12,438
688.00
7,950
7,325 19,763
689.00
9,050
8,500 28,263
690.00
10,150
9,600 37,863
Device Routing
Invert
Outlet Devices
#1 Primary
683.24'
24.0" Round Culvert L= 55.0' Ke= 0.500
Inlet / Outlet Invert= 683.24' / 682.91' S= 0.0060 '/' Cc= 0.900
n= 0.012, Flow Area= 3.14 sf
#2 Device 1
684.50'
Special & User -Defined
Head (feet) 0.00 0.50 1.50 2.50
Disch. (cfs) 0.000 0.054 0.081 0.108
#3 Device 1
687.30'
4.0' long Sharp -Crested Rectangular Weir 2 End Contraction(s)
#4 Device 1
688.30'
16.0' long Sharp -Crested Rectangular Weir 2 End Contraction(s)
Primary OutFlow Max=23.85 cfs @ 3.18 hrs HW=688.55' (Free Discharge)
L =Culvert (Passes 23.85 cfs of 31.41 cfs potential flow)
2=Special & User -Defined (Custom Controls 0.11 cfs)
3=Sharp-Crested Rectangular Weir (Weir Controls 17.16 cfs @ 3.66 fps)
=Sharp -Crested Rectangular Weir (Weir Controls 6.57 cfs @ 1.64 fps)

Sf # 1 HydroCad Charlotte 6-hr 50-yr 50 yr Rainfall=4.92"
Prepared by Yarbrough -Williams & Houle, Inc. Printed 10/14/2020
HydroCAD® 10.10-4a s/n 05047 © 2020 HydroCAD Software Solutions LLC Paae 14
Pond 27P: Sand Filter
Hydrograph
36 { ax.ai ors .l
34 Inflow Area=4.060 ac
32
30 Peak Elev=688.55'
2S
n z,�,�.. Storage=24,454 d
22
20
3 18
0
LL 16
14
12
10
4-
2
0
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 135 140
Time (hours)
C] Inflow
10 Primary

Sf # 1 HydroCad Charlotte 6-hr 100-yr 100 YEAR Rainfall=5.34"
Prepared by Yarbrough -Williams & Houle, Inc. Printed 10/14/2020
HydroCAD®10.10-4a s/n 05047 ©2020 HydroCAD Software Solutions LLC Paoe 15
Summary for Subcatchment 9S: Post Development
Runoff = 36.77 cfs @ 3.11 hrs, Volume= 1.575 af, Depth= 3.89"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-140.00 hrs, dt= 0.01 hrs
Charlotte 6-hr 100-yr 100 YEAR Rainfall=5.34"
Area (ac) CN Description
2.620
98 Paved parking, HSG C
2.240
74 >75% Grass cover, Good. HSG C
4.860
87 Weighted Average
2.240
46.09% Pervious Area
2.620
53.91% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) ft/ft) (ft/sec) (cfs)
5.0 Direct Entry, Post Dev
Subcatchment 9S: Post Development
Hydrograph
40.
3 3677 cfs
36 Charlotte 6-hr
34-
32 100-yr
�$ 100 YEAR Rainfall=5.34"
26 Runoff Area=4.860.ac
24
22 Runoff Volume=1.575 of
20
18 Runoff Depth=3.89"
1S Tc=5.0 m i n
14
12 CN=87
10
8
6
4
2
a
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 135 140
Time (hours)
© Runoff

Sf # 1 HydroCad Charlotte 6-hr 100-yr 100 YEAR Rainfall=5.34"
Prepared by Yarbrough -Williams & Houle, Inc. Printed 10/14/2020
H droCAD@ 10.10-4a s/n 05047 ©2020 H droCAD Software Solutions LLC Page 16
Summary for Pond 27P: Sand Filter
Inflow Area = 4.860 ac, 53.91% Impervious, Inflow Depth = 3.89" for 100 YEAR event
Inflow = 36.77 cfs @ 3.11 hrs, Volume= 1.575 of
Outflow = 29.95 cfs @ 3.16 hrs, Volume= 1.575 af, Atten= 19%, Lag= 3.3 min
Primary = 29.95 cfs @ 3.16 hrs, Volume= 1.575 of
Routing by Stor-Ind method, Time Span= 0.00-140.00 hrs, dt= 0.01 hrs / 2
Peak Elev= 688.65' @ 3.16 hrs Surf.Area= 8,665 sf Storage= 25,284 cf
Plug -Flow detention time= 353.3 min calculated for 1.575 of (100% of inflow)
Center -of -Mass det. time= 353.6 min ( 557.5 - 203.9 )
Volume
Invert Avail.Stora a Storage
Description
#1
684.50'
37,863 cf Custom Stage Data (Prismatic) Listed below
Elevation
Surf.Area
Inc.Store
Cum.Store
(feet)
(sq-ft)
(cubic -feet)
(cubic -feet)
684.50
1,000
0
0
685.00
4,450
1,363
1,363
686.00
5,500
4,975
6,338
687.00
6,700
6,100
12,438
688.00
7,950
7,325
19,763
689.00
9,050
8,500
28,263
690.00
10,150
9,600
37,863
Device Routinq Invert Outlet Devices
#1
Primary
683.24'
24.0" Round Culvert L= 55.0' Ke= 0.500
Inlet / Outlet Invert= 683.24' / 682.91' S= 0.0060 T Cc= 0.900
n= 0.012, Flow Area= 3.14 sf
#2
Device 1
684.50'
Special & User -Defined
Head (feet) 0.00 0.50 1.50 2.50
Disch. (cfs) 0.000 0.054 0.081 0.108
#3
Device 1
687.30'
4.0' long Sharp -Crested Rectangular Weir 2 End Contraction(s)
#4
Device 1
688.30'
16.0' long Sharp -Crested Rectangular Weir 2 End Contraction(s)
Primary OutFiow Max=29.97 cfs @ 3.16 hrs HW=688.65' (Free Discharge)
L1=Culvert (Passes 29.97 cfs of 31.76 cfs potential flow)
2=Special & User -Defined (Custom Controls 0.11 cfs)
3=Sharp-Crested Rectangular Weir (Weir Controls 19.12 cfs @ 3.80 fps)
=Sharp -Crested Rectangular Weir (Weir Controls 10.75 cfs @ 1.93 fps)

Sf # 1 HydroCad Charlotte 6-hr 100-yr 100 YEAR Rainfall=5.34"
Prepared by Yarbrough -Williams & Houle, Inc. Printed 10/14/2020
HvdroCAD®10.10-4a s/n 05047 ©2020 HydroCAD Software Solutions LLC Pace 17
Pond 27P: Sand Filter
Hydrograph
40 3s.77 dz
38. Inflow Area=4:.860 ac
36
34 Peak EI'ev=688.65'
3 z9 as cra
3
28 0 Storage=25,284'cf
26
-. 24
22
20
0
LL 18
16
14
12-
4.
2.
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 160165 110115120125130135140
Time (hours)
Inflow
p Primary

Sf # 1 HydroCad
Prepared by Yarbrough -Williams & Houle, Inc.
HydroCADO 10.10-4a s/n 05047 © 2020 HvdroCAD Software Solutions LLC
TABLE OF CONTENTS
Project Reports
1 Routing Diagram
2 Rainfall Events Listing (selected events)
1 yr Event
3 Subcat 9S: Post Development
4 Pond 27P: Sand Filter
2-yr Event
6 Subcat 9S: Post Development
7 Pond 27P: Sand Filter
10-yr Event
9 Subcat 9S: Post Development
10 Pond 27P: Sand Filter
50 yr Event
12 Subcat 9S: Post Development
13 Pond 27P: Sand Filter
100 YEAR Event
15 Subcat 9S: Post Development
16 Pond 27P: Sand Filter
Table of Contents
Printed 10/14/2020