The Walking Company - SWM Design Report

 
STORMWATER MANAGEMENT REPORT 
FOR 

THE WALKING CO. EXPANSION 
519 LINCOLN COUNTY PKWY EXT. 
LINCOLN COUNTY, NORTH CAROLINA 

BY 
BURTON ENGINEERING ASSOCIATES 
5950 FAIRVIEW ROAD, SUITE 100 
CHARLOTTE, NC 28210 
(704) 553‐8881 

October 26, 2017 

TABLE OF CONTENTS 

I. NARRATIVE 

 Introduction 
Stormwater Management Requirements 
Existing Site Conditions 
Proposed Site Conditions 
Proposed BMP Design 
Conclusions 

II. MAPS AND FIGURES 

 HydroCAD Model Routing Diagram 
 Drainage Area Maps 
 NOAA Rainfall Data 
 Soils Map 
 USGS Map 
 FEMA FIRM Map  

III. HYDROCAD MODEL OUTPUT 

Hydrocad: 1‐inch Storm Event 
  Hydrocad: 1‐yr 24‐hr Storm Event 
  Hydrocad: 10‐yr 24‐hr Storm Event 
  Hydrocad: 50‐yr 24‐hr Storm Event 

IV. STORM DRAINAGE HYDRAULIC MODEL 

Hydraflow Storm Sewers: 10‐yr 24‐hr Storm Event 

V. EROSION CONTROL CALCULATIONS 

Sediment Skimmer Basin Spreadsheet 
Riprap Apron Design 

INTRODUCTION 
In 2006 Exeter Property Group permitted and constructed a 224,000sf industrial building with a future 
planned expansion of 160,000sf.  Exeter is now proposing an expansion of 83,168sf with ****sf parking area. 

STORMWATER MANAGEMENT REQUIREMENTS 
NCDEQ Stormwater Management Requirements 
1. Storage volume must be discharged at a rate equal to or less than the pre‐development discharge rate for 
the 1‐yr 24hr storm event. 
2. All SCMs shall be designed so that they do not cause erosion immediately downslope of the discharge 
point during the peak flow from the 10‐yr storm event.  
3. Control and treatment of the 1 inch storm event 

The NCDEQ Stormwater Design Manual is used as the basis for the water quality SCM.  A sand filter system 
with offline dry detention was chosen as the most practical treatment facility to provide both quantity and 
quality control. These SCMs were designed per the 2017 DEQ BMP Manual, sections C‐0, C‐3, & C‐6. 

EXISTING SITE CONDITIONS 
The site consists of an existing 224,000sf building with roughly 118,000sf of impervious asphalt and concrete 
area. The existing conditions used for detention are assumed from previous surveys to be a hilly (7‐10% slope) 
wooded area of fair condition with a hydraulic soil class of B.  

Figure: Predevelopment Drainage Areas (HydroCAD Model) 

PROPOSED SITE CONDITIONS 
The proposed expansion will add 83,168sf to the existing building area with roughly 168,000sf of impervious 
asphalt and concrete. Roughly 354,000sf of residual land will be left in its current state to drain to the analysis 
point. This residual area is HSG B and overgrown with brush. A minimum Tc of 5mins has been assumed for 
this area. 

Figure: Post Developed Drainage Areas to Analysis Point (HydroCAD Model) 

PROPOSED BMP DESIGN 
The Proposed Sand Filter and Dry Detention system is designed to treat and detain the new Impervious area 
as well as a portion of the existing building.  The proposed SCM system will be designed and constructed to 
meet the requirements of the NCDEQ New Stormwater Design Manual (C‐0, C‐6, C‐12). 

CONCLUSIONS 
The NCDEQ Stormwater Management requirements are met in the proposed Wet Pond to be constructed on‐
site.  Below are the existing and proposed peak flow rates and water surface elevations for the site.   

PRE/POST SUMMARY TABLE Storm Event Predeveloped Drainage Area (cfs) HydroCAD Node 1S Post Developed Area to Pond (cfs) HydroCAD Node 2S Post (Residual) (cfs) HydroCAD Node 6S SCM System HydroCAD Node 6R WSE / Discharge Combined (Total) Discharge (cfs) HydroCAD Node 7P 1.0” 0.00 4.18 0.00 845.75 / 0.15 cfs 0.15 
1yr‐24hr 2.13 21.23 0.05 848.08 / 0.87 cfs 0.87 
10yr‐24hr 16.19 41.32 7.91 849.53 / 7.53 cfs 14.65 
50yr‐24hr 31.66 56.98 20.94 850.12 / 24.32 cfs 43.43 

MAPS & FIGURES 
HydroCAD Model Routing Diagram 
Drainage Area Maps 
Rainfall Data 
Soils Map 

1S
PRE
2S
POST
6S
Post Residual
6R
Outlet Culvert
3P
Forebay
4P
Detention
5P
Sand Filter
7P
Analysis Point
Routing Diagram for Preliminary Model
Prepared by Burton Engineering Associates, Inc, Printed 10/27/2017
HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Subcat Reach Pond Link
Preliminary Model
Printed 10/27/2017Prepared by Burton Engineering Associates, Inc
Page 2HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Area Listing (all nodes)
Area
(acres)
CN Description
(subcatchment-numbers)
0.870 61 >75% Grass cover, Good, HSG B (2S)
8.130 48 Brush, Good, HSG B (6S)
4.530 98 Paved parking, HSG B (2S)
0.370 98 Water Surface, HSG B (2S)
13.900 60 Woods, Fair, HSG B (1S)
27.800 63 TOTAL AREA
Preliminary Model
Printed 10/27/2017Prepared by Burton Engineering Associates, Inc
Page 3HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Soil Listing (all nodes)
Area
(acres)
Soil
Group
Subcatchment
Numbers
0.000 HSG A
27.800 HSG B 1S, 2S, 6S
0.000 HSG C
0.000 HSG D
0.000 Other
27.800 TOTAL AREA
Preliminary Model
Printed 10/27/2017Prepared by Burton Engineering Associates, Inc
Page 4HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Ground Covers (all nodes)
HSG-A
(acres)
HSG-B
(acres)
HSG-C
(acres)
HSG-D
(acres)
Other
(acres)
Total
(acres)
Ground
Cover
Subcatchment
Numbers
0.000 0.870 0.000 0.000 0.000 0.870 >75% Grass cover, Good 2S
0.000 8.130 0.000 0.000 0.000 8.130 Brush, Good 6S
0.000 4.530 0.000 0.000 0.000 4.530 Paved parking 2S
0.000 0.370 0.000 0.000 0.000 0.370 Water Surface 2S
0.000 13.900 0.000 0.000 0.000 13.900 Woods, Fair 1S
0.000 27.800 0.000 0.000 0.000 27.800 TOTAL AREA
Preliminary Model
Printed 10/27/2017Prepared by Burton Engineering Associates, Inc
Page 5HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Pipe Listing (all nodes)
Line# Node
Number
In-Invert
(feet)
Out-Invert
(feet)
Length
(feet)
Slope
(ft/ft)
n Diam/Width
(inches)
Height
(inches)
Inside-Fill
(inches)
1 6R 843.00 840.00 85.0 0.0353 0.012 24.0 0.0 0.0
2 3P 844.07 843.90 34.0 0.0050 0.010 6.0 0.0 0.0
3 4P 842.10 829.44 84.0 0.1507 0.022 24.0 0.0 0.0
4 5P 843.50 842.90 40.0 0.0150 0.010 6.0 0.0 0.0
Type II 24-hr 1-inch-24hr Rainfall=1.00"Preliminary Model
Printed 10/27/2017Prepared by Burton Engineering Associates, Inc
Page 6HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Time span=0.00-120.00 hrs, dt=0.05 hrs, 2401 points
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN
Reach routing by Dyn-Stor-Ind method - Pond routing by Dyn-Stor-Ind method
Runoff Area=13.900 ac 0.00% Impervious Runoff Depth=0.00"Subcatchment 1S: PRE
Flow Length=1,510' Tc=28.9 min CN=60 Runoff=0.00 cfs 0.000 af
Runoff Area=5.770 ac 84.92% Impervious Runoff Depth=0.40"Subcatchment 2S: POST
Tc=5.0 min CN=92 Runoff=4.18 cfs 0.194 af
Runoff Area=354,143 sf 0.00% Impervious Runoff Depth=0.00"Subcatchment 6S: Post Residual
Tc=5.0 min CN=48 Runoff=0.00 cfs 0.000 af
Avg. Flow Depth=0.08' Max Vel=3.35 fps Inflow=0.15 cfs 0.194 afReach 6R: Outlet Culvert
24.0" Round Pipe n=0.012 L=85.0' S=0.0353 '/' Capacity=46.04 cfs Outflow=0.15 cfs 0.194 af
Peak Elev=846.70' Storage=2,296 cf Inflow=4.18 cfs 0.194 afPond 3P: Forebay
Primary=1.08 cfs 0.194 af Secondary=0.00 cfs 0.000 af Outflow=1.08 cfs 0.194 af
Peak Elev=845.00' Storage=0 cf Inflow=0.00 cfs 0.000 afPond 4P: Detention
Primary=0.00 cfs 0.000 af Secondary=0.00 cfs 0.000 af Outflow=0.00 cfs 0.000 af
Peak Elev=845.75' Storage=3,937 cf Inflow=1.08 cfs 0.194 afPond 5P: Sand Filter
Primary=0.15 cfs 0.194 af Secondary=0.00 cfs 0.000 af Outflow=0.15 cfs 0.194 af
Inflow=0.15 cfs 0.194 afPond 7P: Analysis Point
Primary=0.15 cfs 0.194 af
Total Runoff Area = 27.800 ac Runoff Volume = 0.194 af Average Runoff Depth = 0.08"
82.37% Pervious = 22.900 ac 17.63% Impervious = 4.900 ac
Point precipitation frequency estimates (inches/hour)NOAA Atlas 14 Volume 2 Version 3Data type: Precipitation intensityTime series type: Partial durationProject area: Ohio River BasinLocation na North Caro USAStation Name: ‐Latitude: 35.5220°Longitude: ‐81.1999°Elevation (USGS): None NonePRECIPITATION FREQUENCY ESTIMATESby duration1 2 5 10 25 50 100 200 500 10005‐min: 4.63 5.48 6.44 7.15 8 8.62 9.2 9.77 10.45 10.9710‐min: 3.7 4.39 5.15 5.72 6.38 6.86 7.31 7.74 8.26 8.6315‐min: 3.09 3.68 4.35 4.82 5.39 5.79 6.16 6.51 6.93 7.2230‐min: 2.12 2.54 3.09 3.49 3.99 4.36 4.72 5.07 5.52 5.8560‐min: 1.32 1.59 1.98 2.27 2.66 2.96 3.25 3.55 3.96 4.272‐hr: 0.77 0.93 1.16 1.35 1.59 1.79 1.99 2.19 2.47 2.73‐hr: 0.55 0.66 0.83 0.96 1.15 1.3 1.46 1.62 1.86 2.056‐hr: 0.34 0.4 0.51 0.59 0.7 0.8 0.89 1 1.14 1.2612‐hr: 0.2 0.24 0.31 0.36 0.43 0.48 0.54 0.6 0.69 0.7624‐hr: 0.12 0.15 0.19 0.22 0.26 0.29 0.32 0.36 0.41 0.452‐day: 0.07 0.09 0.11 0.13 0.15 0.17 0.19 0.21 0.23 0.253‐day: 0.05 0.06 0.08 0.09 0.1 0.12 0.13 0.14 0.16 0.184‐day: 0.04 0.05 0.06 0.07 0.08 0.09 0.1 0.11 0.13 0.147‐day: 0.03 0.03 0.04 0.04 0.05 0.06 0.06 0.07 0.08 0.0810‐day: 0.02 0.03 0.03 0.03 0.04 0.04 0.05 0.05 0.06 0.0620‐day: 0.01 0.02 0.02 0.02 0.03 0.03 0.03 0.03 0.04 0.0430‐day: 0.01 0.01 0.02 0.02 0.02 0.02 0.02 0.02 0.03 0.0345‐day: 0.01 0.01 0.01 0.01 0.02 0.02 0.02 0.02 0.02 0.0260‐day: 0.01 0.01 0.01 0.01 0.01 0.01 0.02 0.02 0.02 0.02Date/time (GMT):  Mon Mar 27 18:09:12 2017pyRunTime:  0.0512480735779

SAND FILTER DESIGN 

Sand Filter NCDENR 2007 10/27/2017BRYTON
HAMBRIGHT ROAD WATER QUALITY
SAND FILTER DESIGN Updated per NCDENR 2007 BMP Manual & Sept 2009
85% Total Suspended Solids
35% Total Nitrogen
45% total Phosphate
COMPUTE WATER QUALITY VOLUME
Drainage Area =5.77 ac
% Impervious = 82.00 %
Curve Number = 92.00
USE SIMPLE METHODRv=0.05+0.009(I)
Rv=0.05+0.009(I) 0.788 IN/IN
P= 1.0 IN
S = 0.870
PModified =1.48
Pactual =1.73 (rainfall generating 1" of runoff in HydroCAD)
WQV = 16,505 ft3
WQV Adj = 12,379 ft3
DETERMINE FILTER BED & SEDIMENTATION BASIN SURFACE AREA
h MaxFilter =
h MaxFilter 4.43
Assume h MaxFilter
h MaxFilter 2.00 ft Min. (As + AF)= 3,408 ft2
3.0
Min. Area for Sedimentation Chamber Min. Area for Sand Filter
AS = [240*Rv*A]*Rd
AS =1,089 ft2 Af = 1,704 ft2 Elev
Bottom Area Used = 2,000 ft2 Bottom Area Used = 1,704.00 ft2 845
3.5 ft/day x 1.66 days x (Avg Head + 1.5 ft)Af =WQV x 1.5 ft
WQV Adj (ft3)
As (ft2) + Af (ft2)
A diversion or bypass structure 
must divert all but the design 
flow for the filter
Maximum contributing drainage 
area to a Sand Filter is 5 acres
Choose a combination of Af & hMaxFilter to 
meet the space available.  Sedimentation 
Chamber and Sand Filter should be about 
the same size.
Maximum Head on the Sand Filter must 
not exceed 6 ft (Design Storm only)
Modified P to account for the rainfall loss in the 1" Storm
(to be used  in lieu of the 1" depth in the  SCS rainfall distribution)
Q= ( P‐Ia )^2/( P‐Ia +S )
solved for P  = [ ( 4Q x S + Q^2 )^1/2 + Q + 2 x Ia ] / 2
Page 1 of 5
Sand Filter NCDENR 2007 10/27/2017
Top Area Used = 6,722 ft2 Top Area Used = 3,627 ft2 847
8,722 ft3 5,331 ft3
VERIFY VOLUMES
Voltotal =( As + Af ) x hMaxFilter
Voltotal = 14,053 ft3
Compare to WQVAdj
P:\DWG\017.667.001 519 Lincoln County Parkway\6. Calcs\SWM\Excel\NCDENRWqcalcs1C.xls Page 2 of 5
Sand Filter NCDENR 2007 10/27/2017
SIZE UNDERDRAIN SYSTEM
Determine capacity of Under Drain System
Af = WQv x df / [ ( k x Hf +Df) x Tf ]
Where:
Af = 1,704 ft2 surface area of filter bed
df = 1.5 ft filter bed depth
k = 3.5 ft/day coefficient of permeability media
hf = 1.00 ft average height of water above filter bed, (Hmax / 2)
Tf = 1.66 Days (40 Hours, 1.66 Days))
2.0 Ft Max. Depth of Storage Volume
Af Provided=806 ft2 surface area provided (806 sf Bottom of Sand)
Q at Full Depth = 0.076 cfs
Q at Avg Depth = 0.054 cfs
Time to Drain= 84.90 hrs
Safety Factor of 10 0.540 cfs
Compute Perforation Capacity
Pipes Length 4 Holes/Row
# of Perforations = 1 290 4 = 2320 Holes
50% of Perforations = 1160 Holes
Capacity of One Hole = CA(2gh)^0.5
0.007 cfs/Hole
Total Capacity = 8.023 cfs
apacity of Filter Media = 0.540 cfs
Perforation Capacity =>Media Capac OK
Bottom of sand to have min surface area 
as well.  May go to 1:1 slope
3/8" Dia. Hole
Holes spaced 6" o/c.
Min of 2 pipes  Max 10' o/c
P:\DWG\017.667.001 519 Lincoln County Parkway\6. Calcs\SWM\Excel\NCDENRWqcalcs1C.xls Page 3 of 5

HYDROCAD OUTPUT 
1.0‐inch Storm Event 

Type II 24-hr 1-inch-24hr Rainfall=1.00"Preliminary Model
Printed 10/27/2017Prepared by Burton Engineering Associates, Inc
Page 7HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Summary for Subcatchment 1S: PRE
[45] Hint: Runoff=Zero
Runoff = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af, Depth= 0.00"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs
Type II 24-hr 1-inch-24hr Rainfall=1.00"
Area (ac) CN Description
13.900 60 Woods, Fair, HSG B
13.900 100.00% Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
26.7 300 0.0900 0.19 Sheet Flow,
Woods: Light underbrush n= 0.400 P2= 3.61"
1.0 257 0.0733 4.36 Shallow Concentrated Flow,
Unpaved Kv= 16.1 fps
1.2 953 0.0100 13.39 1,311.77 Channel Flow,
Area= 98.0 sf Perim= 29.0' r= 3.38'
n= 0.025 Earth, clean & winding
28.9 1,510 Total
Subcatchment 1S: PRE
Runoff
Hydrograph
Time (hours)
12011511010510095908580757065605550454035302520151050Flow (cfs)1
0
Type II 24-hr
1-inch-24hr Rainfall=1.00"
Runoff Area=13.900 ac
Runoff Volume=0.000 af
Runoff Depth=0.00"
Flow Length=1,510'
Tc=28.9 min
CN=60
0.00 cfs
Type II 24-hr 1-inch-24hr Rainfall=1.00"Preliminary Model
Printed 10/27/2017Prepared by Burton Engineering Associates, Inc
Page 8HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Summary for Subcatchment 2S: POST
[49] Hint: Tc<2dt may require smaller dt
Runoff = 4.18 cfs @ 11.96 hrs, Volume= 0.194 af, Depth= 0.40"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs
Type II 24-hr 1-inch-24hr Rainfall=1.00"
Area (ac) CN Description
0.370 98 Water Surface, HSG B
4.530 98 Paved parking, HSG B
0.870 61 >75% Grass cover, Good, HSG B
5.770 92 Weighted Average
0.870 15.08% Pervious Area
4.900 84.92% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
Subcatchment 2S: POST
Runoff
Hydrograph
Time (hours)
12011511010510095908580757065605550454035302520151050Flow (cfs)4
3
2
1
0
Type II 24-hr
1-inch-24hr Rainfall=1.00"
Runoff Area=5.770 ac
Runoff Volume=0.194 af
Runoff Depth=0.40"
Tc=5.0 min
CN=92
4.18 cfs
Type II 24-hr 1-inch-24hr Rainfall=1.00"Preliminary Model
Printed 10/27/2017Prepared by Burton Engineering Associates, Inc
Page 9HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Summary for Subcatchment 6S: Post Residual
[49] Hint: Tc<2dt may require smaller dt
[45] Hint: Runoff=Zero
Runoff = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af, Depth= 0.00"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs
Type II 24-hr 1-inch-24hr Rainfall=1.00"
Area (sf) CN Description
354,143 48 Brush, Good, HSG B
354,143 100.00% Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
Subcatchment 6S: Post Residual
Runoff
Hydrograph
Time (hours)
12011511010510095908580757065605550454035302520151050Flow (cfs)1
0
Type II 24-hr
1-inch-24hr Rainfall=1.00"
Runoff Area=354,143 sf
Runoff Volume=0.000 af
Runoff Depth=0.00"
Tc=5.0 min
CN=48
0.00 cfs
Type II 24-hr 1-inch-24hr Rainfall=1.00"Preliminary Model
Printed 10/27/2017Prepared by Burton Engineering Associates, Inc
Page 10HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Summary for Reach 6R: Outlet Culvert
[52] Hint: Inlet/Outlet conditions not evaluated
Inflow Area = 5.770 ac, 84.92% Impervious, Inflow Depth = 0.40" for 1-inch-24hr event
Inflow = 0.15 cfs @ 14.11 hrs, Volume= 0.194 af
Outflow = 0.15 cfs @ 14.12 hrs, Volume= 0.194 af, Atten= 0%, Lag= 0.3 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs
Max. Velocity= 3.35 fps, Min. Travel Time= 0.4 min
Avg. Velocity = 1.99 fps, Avg. Travel Time= 0.7 min
Peak Storage= 4 cf @ 14.12 hrs
Average Depth at Peak Storage= 0.08'
Bank-Full Depth= 2.00' Flow Area= 3.1 sf, Capacity= 46.04 cfs
24.0" Round Pipe
n= 0.012
Length= 85.0' Slope= 0.0353 '/'
Inlet Invert= 843.00', Outlet Invert= 840.00'
Reach 6R: Outlet Culvert
Inflow
Outflow
Hydrograph
Time (hours)
12011511010510095908580757065605550454035302520151050Flow (cfs)0.16
0.15
0.14
0.13
0.12
0.11
0.1
0.09
0.08
0.07
0.06
0.05
0.04
0.03
0.02
0.01
0
Inflow Area=5.770 ac
Avg. Flow Depth=0.08'
Max Vel=3.35 fps
24.0"
Round Pipe
n=0.012
L=85.0'
S=0.0353 '/'
Capacity=46.04 cfs
0.15 cfs0.15 cfs
Type II 24-hr 1-inch-24hr Rainfall=1.00"Preliminary Model
Printed 10/27/2017Prepared by Burton Engineering Associates, Inc
Page 11HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Stage-Area-Storage for Reach 6R: Outlet Culvert
Elevation
(feet)
End-Area
(sq-ft)
Storage
(cubic-feet)
843.00 0.0 0
843.02 0.0 0
843.04 0.0 1
843.06 0.0 2
843.08 0.0 4
843.10 0.1 5
843.12 0.1 7
843.14 0.1 8
843.16 0.1 10
843.18 0.1 12
843.20 0.2 14
843.22 0.2 16
843.24 0.2 18
843.26 0.2 20
843.28 0.3 23
843.30 0.3 25
843.32 0.3 28
843.34 0.4 30
843.36 0.4 33
843.38 0.4 35
843.40 0.4 38
843.42 0.5 41
843.44 0.5 44
843.46 0.5 46
843.48 0.6 49
843.50 0.6 52
843.52 0.6 55
843.54 0.7 58
843.56 0.7 61
843.58 0.8 64
843.60 0.8 67
843.62 0.8 71
843.64 0.9 74
843.66 0.9 77
843.68 0.9 80
843.70 1.0 83
843.72 1.0 87
843.74 1.1 90
843.76 1.1 93
843.78 1.1 96
843.80 1.2 100
843.82 1.2 103
843.84 1.3 106
843.86 1.3 110
843.88 1.3 113
843.90 1.4 117
843.92 1.4 120
843.94 1.5 123
843.96 1.5 127
843.98 1.5 130
844.00 1.6 134
844.02 1.6 137
844.04 1.7 140
Elevation
(feet)
End-Area
(sq-ft)
Storage
(cubic-feet)
844.06 1.7 144
844.08 1.7 147
844.10 1.8 150
844.12 1.8 154
844.14 1.8 157
844.16 1.9 161
844.18 1.9 164
844.20 2.0 167
844.22 2.0 171
844.24 2.0 174
844.26 2.1 177
844.28 2.1 180
844.30 2.2 184
844.32 2.2 187
844.34 2.2 190
844.36 2.3 193
844.38 2.3 197
844.40 2.3 200
844.42 2.4 203
844.44 2.4 206
844.46 2.5 209
844.48 2.5 212
844.50 2.5 215
844.52 2.6 218
844.54 2.6 221
844.56 2.6 223
844.58 2.7 226
844.60 2.7 229
844.62 2.7 232
844.64 2.8 234
844.66 2.8 237
844.68 2.8 239
844.70 2.8 242
844.72 2.9 244
844.74 2.9 247
844.76 2.9 249
844.78 3.0 251
844.80 3.0 253
844.82 3.0 255
844.84 3.0 257
844.86 3.0 259
844.88 3.1 260
844.90 3.1 262
844.92 3.1 263
844.94 3.1 265
844.96 3.1 266
844.98 3.1 267
845.00 3.1 267
Type II 24-hr 1-inch-24hr Rainfall=1.00"Preliminary Model
Printed 10/27/2017Prepared by Burton Engineering Associates, Inc
Page 12HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Summary for Pond 3P: Forebay
Inflow Area = 5.770 ac, 84.92% Impervious, Inflow Depth = 0.40" for 1-inch-24hr event
Inflow = 4.18 cfs @ 11.96 hrs, Volume= 0.194 af
Outflow = 1.08 cfs @ 12.11 hrs, Volume= 0.194 af, Atten= 74%, Lag= 8.6 min
Primary = 1.08 cfs @ 12.11 hrs, Volume= 0.194 af
Secondary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af
Routing by Dyn-Stor-Ind method, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs
Peak Elev= 846.70' @ 12.11 hrs Surf.Area= 2,116 sf Storage= 2,296 cf
Plug-Flow detention time= 60.8 min calculated for 0.193 af (100% of inflow)
Center-of-Mass det. time= 60.9 min ( 905.1 - 844.2 )
Volume Invert Avail.Storage Storage Description
#1 844.57' 29,501 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
844.57 0 0 0
845.00 575 124 124
846.00 1,350 963 1,086
847.00 2,446 1,898 2,984
848.00 4,207 3,327 6,311
849.00 6,961 5,584 11,895
850.00 8,723 7,842 19,737
851.00 10,805 9,764 29,501
Device Routing Invert Outlet Devices
#1 Primary 844.07'6.0" Round Culvert
L= 34.0' RCP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 844.07' / 843.90' S= 0.0050 '/' Cc= 0.900
n= 0.010, Flow Area= 0.20 sf
#2 Device 1 844.57'1.0" Vert. Orifice/Grate X 5.00 columns
X 6 rows with 1.0" cc spacing C= 0.600
#3 Secondary 848.20'60.0' long x 6.0' breadth Broad-Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00
2.50 3.00 3.50 4.00 4.50 5.00 5.50
Coef. (English) 2.37 2.51 2.70 2.68 2.68 2.67 2.65 2.65 2.65
2.65 2.66 2.66 2.67 2.69 2.72 2.76 2.83
#4 Primary 849.50'60.0' long x 6.0' breadth Broad-Crested Rectangular Weir X 0.00
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00
2.50 3.00 3.50 4.00 4.50 5.00 5.50
Coef. (English) 2.37 2.51 2.70 2.68 2.68 2.67 2.65 2.65 2.65
2.65 2.66 2.66 2.67 2.69 2.72 2.76 2.83
Type II 24-hr 1-inch-24hr Rainfall=1.00"Preliminary Model
Printed 10/27/2017Prepared by Burton Engineering Associates, Inc
Page 13HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Primary OutFlow Max=1.07 cfs @ 12.11 hrs HW=846.70' TW=844.68' (Dynamic Tailwater)
1=Culvert (Passes 1.07 cfs of 1.27 cfs potential flow)
2=Orifice/Grate (Orifice Controls 1.07 cfs @ 6.57 fps)
4=Broad-Crested Rectangular Weir ( Controls 0.00 cfs)
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=844.57' TW=845.00' (Dynamic Tailwater)
3=Broad-Crested Rectangular Weir ( Controls 0.00 cfs)
Pond 3P: Forebay
Inflow
Outflow
Primary
Secondary
Hydrograph
Time (hours)
12011511010510095908580757065605550454035302520151050Flow (cfs)4
3
2
1
0
Inflow Area=5.770 ac
Peak Elev=846.70'
Storage=2,296 cf
4.18 cfs
1.08 cfs1.08 cfs
0.00 cfs
Type II 24-hr 1-inch-24hr Rainfall=1.00"Preliminary Model
Printed 10/27/2017Prepared by Burton Engineering Associates, Inc
Page 14HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Stage-Area-Storage for Pond 3P: Forebay
Elevation
(feet)
Surface
(sq-ft)
Storage
(cubic-feet)
844.57 0 0
844.67 134 7
844.77 267 27
844.87 401 60
844.97 535 107
845.07 629 166
845.17 707 233
845.27 784 307
845.37 862 389
845.47 939 479
845.57 1,017 577
845.67 1,094 683
845.77 1,172 796
845.87 1,249 917
845.97 1,327 1,046
846.07 1,427 1,183
846.17 1,536 1,331
846.27 1,646 1,491
846.37 1,756 1,661
846.47 1,865 1,842
846.57 1,975 2,034
846.67 2,084 2,237
846.77 2,194 2,451
846.87 2,304 2,675
846.97 2,413 2,911
847.07 2,569 3,160
847.17 2,745 3,425
847.27 2,921 3,709
847.37 3,098 4,010
847.47 3,274 4,328
847.57 3,450 4,664
847.67 3,626 5,018
847.77 3,802 5,390
847.87 3,978 5,779
847.97 4,154 6,185
848.07 4,400 6,612
848.17 4,675 7,066
848.27 4,951 7,547
848.37 5,226 8,056
848.47 5,501 8,592
848.57 5,777 9,156
848.67 6,052 9,747
848.77 6,328 10,366
848.87 6,603 11,013
848.97 6,878 11,687
849.07 7,084 12,386
849.17 7,261 13,103
849.27 7,437 13,838
849.37 7,613 14,591
849.47 7,789 15,361
849.57 7,965 16,149
849.67 8,142 16,954
849.77 8,318 17,777
Elevation
(feet)
Surface
(sq-ft)
Storage
(cubic-feet)
849.87 8,494 18,618
849.97 8,670 19,476
850.07 8,869 20,352
850.17 9,077 21,250
850.27 9,285 22,168
850.37 9,493 23,107
850.47 9,702 24,066
850.57 9,910 25,047
850.67 10,118 26,048
850.77 10,326 27,071
850.87 10,534 28,114
850.97 10,743 29,177
Type II 24-hr 1-inch-24hr Rainfall=1.00"Preliminary Model
Printed 10/27/2017Prepared by Burton Engineering Associates, Inc
Page 15HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Summary for Pond 4P: Detention
Inflow = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af
Outflow = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af, Atten= 0%, Lag= 0.0 min
Primary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af
Secondary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af
Routing by Dyn-Stor-Ind method, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs
Peak Elev= 845.00' @ 0.00 hrs Surf.Area= 1,060 sf Storage= 0 cf
Plug-Flow detention time= (not calculated: initial storage exceeds outflow)
Center-of-Mass det. time= (not calculated: no inflow)
Volume Invert Avail.Storage Storage Description
#1 845.00' 36,958 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
845.00 1,060 0 0
846.00 4,240 2,650 2,650
847.00 5,163 4,702 7,352
848.00 6,263 5,713 13,065
849.00 7,370 6,817 19,881
850.00 8,496 7,933 27,814
851.00 9,792 9,144 36,958
Device Routing Invert Outlet Devices
#1 Primary 842.10'24.0" Round Culvert
L= 84.0' CMP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 842.10' / 829.44' S= 0.1507 '/' Cc= 0.900
n= 0.022, Flow Area= 3.14 sf
#2 Device 1 845.00'1.5" Horiz. 1yr - Orifice C= 0.600 Limited to weir flow at low heads
#3 Device 1 847.60'10.0" W x 24.0" H Vert. 10yr - Orifice C= 0.600
#4 Device 1 849.60'36.0" W x 6.0" H Vert. 50yr - Orifice X 4.00 C= 0.600
#5 Secondary 850.00'60.0' long x 8.0' breadth Broad-Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00
2.50 3.00 3.50 4.00 4.50 5.00 5.50
Coef. (English) 2.43 2.54 2.70 2.69 2.68 2.68 2.66 2.64 2.64
2.64 2.65 2.65 2.66 2.66 2.68 2.70 2.74
Primary OutFlow Max=0.00 cfs @ 0.00 hrs HW=845.00' TW=843.00' (Dynamic Tailwater)
1=Culvert (Passes 0.00 cfs of 16.81 cfs potential flow)
2=1yr - Orifice ( Controls 0.00 cfs)
3=10yr - Orifice ( Controls 0.00 cfs)
4=50yr - Orifice ( Controls 0.00 cfs)
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=845.00' (Free Discharge)
5=Broad-Crested Rectangular Weir ( Controls 0.00 cfs)
Type II 24-hr 1-inch-24hr Rainfall=1.00"Preliminary Model
Printed 10/27/2017Prepared by Burton Engineering Associates, Inc
Page 16HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Pond 4P: Detention
Inflow
Outflow
Primary
Secondary
Hydrograph
Time (hours)
12011511010510095908580757065605550454035302520151050Flow (cfs)1
0
Peak Elev=845.00'
Storage=0 cf
0.00 cfs0.00 cfs0.00 cfs0.00 cfs
Type II 24-hr 1-inch-24hr Rainfall=1.00"Preliminary Model
Printed 10/27/2017Prepared by Burton Engineering Associates, Inc
Page 17HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Stage-Area-Storage for Pond 4P: Detention
Elevation
(feet)
Surface
(sq-ft)
Storage
(cubic-feet)
845.00 1,060 0
845.10 1,378 122
845.20 1,696 276
845.30 2,014 461
845.40 2,332 678
845.50 2,650 928
845.60 2,968 1,208
845.70 3,286 1,521
845.80 3,604 1,866
845.90 3,922 2,242
846.00 4,240 2,650
846.10 4,332 3,079
846.20 4,425 3,516
846.30 4,517 3,964
846.40 4,609 4,420
846.50 4,702 4,885
846.60 4,794 5,360
846.70 4,886 5,844
846.80 4,978 6,337
846.90 5,071 6,840
847.00 5,163 7,352
847.10 5,273 7,873
847.20 5,383 8,406
847.30 5,493 8,950
847.40 5,603 9,505
847.50 5,713 10,071
847.60 5,823 10,647
847.70 5,933 11,235
847.80 6,043 11,834
847.90 6,153 12,444
848.00 6,263 13,065
848.10 6,374 13,696
848.20 6,484 14,339
848.30 6,595 14,993
848.40 6,706 15,658
848.50 6,817 16,334
848.60 6,927 17,022
848.70 7,038 17,720
848.80 7,149 18,429
848.90 7,259 19,150
849.00 7,370 19,881
849.10 7,483 20,624
849.20 7,595 21,378
849.30 7,708 22,143
849.40 7,820 22,919
849.50 7,933 23,707
849.60 8,046 24,506
849.70 8,158 25,316
849.80 8,271 26,137
849.90 8,383 26,970
850.00 8,496 27,814
850.10 8,626 28,670
850.20 8,755 29,539
Elevation
(feet)
Surface
(sq-ft)
Storage
(cubic-feet)
850.30 8,885 30,421
850.40 9,014 31,316
850.50 9,144 32,224
850.60 9,274 33,145
850.70 9,403 34,079
850.80 9,533 35,026
850.90 9,662 35,985
851.00 9,792 36,958
Type II 24-hr 1-inch-24hr Rainfall=1.00"Preliminary Model
Printed 10/27/2017Prepared by Burton Engineering Associates, Inc
Page 18HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Summary for Pond 5P: Sand Filter
Inflow Area = 5.770 ac, 84.92% Impervious, Inflow Depth = 0.40" for 1-inch-24hr event
Inflow = 1.08 cfs @ 12.11 hrs, Volume= 0.194 af
Outflow = 0.15 cfs @ 14.11 hrs, Volume= 0.194 af, Atten= 86%, Lag= 120.5 min
Primary = 0.15 cfs @ 14.11 hrs, Volume= 0.194 af
Secondary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af
Routing by Dyn-Stor-Ind method, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs
Peak Elev= 845.75' @ 14.11 hrs Surf.Area= 2,752 sf Storage= 3,937 cf
Plug-Flow detention time= 394.0 min calculated for 0.194 af (100% of inflow)
Center-of-Mass det. time= 393.4 min ( 1,298.6 - 905.1 )
Volume Invert Avail.Storage Storage Description
#1 844.00' 29,322 cf Custom Stage Data (Prismatic) Listed below
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
844.00 1,705 0 0
845.00 2,268 1,987 1,987
846.00 2,911 2,590 4,576
847.00 3,627 3,269 7,845
848.00 4,417 4,022 11,867
849.00 5,279 4,848 16,715
850.00 6,213 5,746 22,461
851.00 7,509 6,861 29,322
Device Routing Invert Outlet Devices
#1 Primary 843.50'6.0" Round Culvert
L= 40.0' RCP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 843.50' / 842.90' S= 0.0150 '/' Cc= 0.900
n= 0.010 PVC, smooth interior, Flow Area= 0.20 sf
#2 Device 1 844.00'Special & User-Defined
Head (feet) 0.00 1.50 3.00 4.50 6.00
Disch. (cfs) 0.000 0.138 0.207 0.276 0.345
#3 Secondary 849.50'60.0' long x 6.0' breadth Broad-Crested Rectangular Weir X 0.00
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00
2.50 3.00 3.50 4.00 4.50 5.00 5.50
Coef. (English) 2.37 2.51 2.70 2.68 2.68 2.67 2.65 2.65 2.65
2.65 2.66 2.66 2.67 2.69 2.72 2.76 2.83
Primary OutFlow Max=0.15 cfs @ 14.11 hrs HW=845.75' TW=843.08' (Dynamic Tailwater)
1=Culvert (Passes 0.15 cfs of 1.32 cfs potential flow)
2=Special & User-Defined (Custom Controls 0.15 cfs)
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=844.00' TW=845.00' (Dynamic Tailwater)
3=Broad-Crested Rectangular Weir ( Controls 0.00 cfs)
Type II 24-hr 1-inch-24hr Rainfall=1.00"Preliminary Model
Printed 10/27/2017Prepared by Burton Engineering Associates, Inc
Page 19HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Pond 5P: Sand Filter
Inflow
Outflow
Primary
Secondary
Hydrograph
Time (hours)
12011511010510095908580757065605550454035302520151050Flow (cfs)1
0
Inflow Area=5.770 ac
Peak Elev=845.75'
Storage=3,937 cf
1.08 cfs
0.15 cfs0.15 cfs
0.00 cfs
Type II 24-hr 1-inch-24hr Rainfall=1.00"Preliminary Model
Printed 10/27/2017Prepared by Burton Engineering Associates, Inc
Page 20HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Stage-Area-Storage for Pond 5P: Sand Filter
Elevation
(feet)
Surface
(sq-ft)
Storage
(cubic-feet)
844.00 1,705 0
844.10 1,761 199
844.20 1,818 397
844.30 1,874 596
844.40 1,930 795
844.50 1,987 993
844.60 2,043 1,192
844.70 2,099 1,391
844.80 2,155 1,589
844.90 2,212 1,788
845.00 2,268 1,987
845.10 2,332 2,245
845.20 2,397 2,504
845.30 2,461 2,763
845.40 2,525 3,022
845.50 2,590 3,281
845.60 2,654 3,540
845.70 2,718 3,799
845.80 2,782 4,058
845.90 2,847 4,317
846.00 2,911 4,576
846.10 2,983 4,903
846.20 3,054 5,230
846.30 3,126 5,557
846.40 3,197 5,884
846.50 3,269 6,211
846.60 3,341 6,537
846.70 3,412 6,864
846.80 3,484 7,191
846.90 3,555 7,518
847.00 3,627 7,845
847.10 3,706 8,247
847.20 3,785 8,649
847.30 3,864 9,052
847.40 3,943 9,454
847.50 4,022 9,856
847.60 4,101 10,258
847.70 4,180 10,660
847.80 4,259 11,063
847.90 4,338 11,465
848.00 4,417 11,867
848.10 4,503 12,352
848.20 4,589 12,837
848.30 4,676 13,321
848.40 4,762 13,806
848.50 4,848 14,291
848.60 4,934 14,776
848.70 5,020 15,261
848.80 5,107 15,745
848.90 5,193 16,230
849.00 5,279 16,715
849.10 5,372 17,290
849.20 5,466 17,864
Elevation
(feet)
Surface
(sq-ft)
Storage
(cubic-feet)
849.30 5,559 18,439
849.40 5,653 19,013
849.50 5,746 19,588
849.60 5,839 20,163
849.70 5,933 20,737
849.80 6,026 21,312
849.90 6,120 21,886
850.00 6,213 22,461
850.10 6,343 23,147
850.20 6,472 23,833
850.30 6,602 24,519
850.40 6,731 25,205
850.50 6,861 25,892
850.60 6,991 26,578
850.70 7,120 27,264
850.80 7,250 27,950
850.90 7,379 28,636
851.00 7,509 29,322
Type II 24-hr 1-inch-24hr Rainfall=1.00"Preliminary Model
Printed 10/27/2017Prepared by Burton Engineering Associates, Inc
Page 21HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Summary for Pond 7P: Analysis Point
[40] Hint: Not Described (Outflow=Inflow)
Inflow Area = 13.900 ac, 35.25% Impervious, Inflow Depth = 0.17" for 1-inch-24hr event
Inflow = 0.15 cfs @ 14.12 hrs, Volume= 0.194 af
Primary = 0.15 cfs @ 14.12 hrs, Volume= 0.194 af, Atten= 0%, Lag= 0.0 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs
Pond 7P: Analysis Point
Inflow
Primary
Hydrograph
Time (hours)
12011511010510095908580757065605550454035302520151050Flow (cfs)0.16
0.15
0.14
0.13
0.12
0.11
0.1
0.09
0.08
0.07
0.06
0.05
0.04
0.03
0.02
0.01
0
Inflow Area=13.900 ac
0.15 cfs0.15 cfs

HYDROCAD OUTPUT 
1yr‐24hr Storm Event 

Type II 24-hr 1yr-24hr Rainfall=2.98"Preliminary Model
Printed 10/27/2017Prepared by Burton Engineering Associates, Inc
Page 22HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Time span=0.00-120.00 hrs, dt=0.05 hrs, 2401 points
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN
Reach routing by Dyn-Stor-Ind method - Pond routing by Dyn-Stor-Ind method
Runoff Area=13.900 ac 0.00% Impervious Runoff Depth=0.33"Subcatchment 1S: PRE
Flow Length=1,510' Tc=28.9 min CN=60 Runoff=2.13 cfs 0.378 af
Runoff Area=5.770 ac 84.92% Impervious Runoff Depth=2.14"Subcatchment 2S: POST
Tc=5.0 min CN=92 Runoff=21.23 cfs 1.030 af
Runoff Area=354,143 sf 0.00% Impervious Runoff Depth=0.06"Subcatchment 6S: Post Residual
Tc=5.0 min CN=48 Runoff=0.05 cfs 0.038 af
Avg. Flow Depth=0.19' Max Vel=5.70 fps Inflow=0.87 cfs 1.030 afReach 6R: Outlet Culvert
24.0" Round Pipe n=0.012 L=85.0' S=0.0353 '/' Capacity=46.04 cfs Outflow=0.87 cfs 1.030 af
Peak Elev=848.47' Storage=8,609 cf Inflow=21.23 cfs 1.030 afPond 3P: Forebay
Primary=1.25 cfs 0.698 af Secondary=20.59 cfs 0.332 af Outflow=21.84 cfs 1.030 af
Peak Elev=847.96' Storage=12,808 cf Inflow=20.59 cfs 0.332 afPond 4P: Detention
Primary=0.68 cfs 0.332 af Secondary=0.00 cfs 0.000 af Outflow=0.68 cfs 0.332 af
Peak Elev=848.08' Storage=12,278 cf Inflow=1.25 cfs 0.698 afPond 5P: Sand Filter
Primary=0.26 cfs 0.698 af Secondary=0.00 cfs 0.000 af Outflow=0.26 cfs 0.698 af
Inflow=0.87 cfs 1.069 afPond 7P: Analysis Point
Primary=0.87 cfs 1.069 af
Total Runoff Area = 27.800 ac Runoff Volume = 1.446 af Average Runoff Depth = 0.62"
82.37% Pervious = 22.900 ac 17.63% Impervious = 4.900 ac
Type II 24-hr 1yr-24hr Rainfall=2.98"Preliminary Model
Printed 10/27/2017Prepared by Burton Engineering Associates, Inc
Page 23HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Summary for Subcatchment 1S: PRE
Runoff = 2.13 cfs @ 12.33 hrs, Volume= 0.378 af, Depth= 0.33"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs
Type II 24-hr 1yr-24hr Rainfall=2.98"
Area (ac) CN Description
13.900 60 Woods, Fair, HSG B
13.900 100.00% Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
26.7 300 0.0900 0.19 Sheet Flow,
Woods: Light underbrush n= 0.400 P2= 3.61"
1.0 257 0.0733 4.36 Shallow Concentrated Flow,
Unpaved Kv= 16.1 fps
1.2 953 0.0100 13.39 1,311.77 Channel Flow,
Area= 98.0 sf Perim= 29.0' r= 3.38'
n= 0.025 Earth, clean & winding
28.9 1,510 Total
Subcatchment 1S: PRE
Runoff
Hydrograph
Time (hours)
12011511010510095908580757065605550454035302520151050Flow (cfs)2
1
0
Type II 24-hr
1yr-24hr Rainfall=2.98"
Runoff Area=13.900 ac
Runoff Volume=0.378 af
Runoff Depth=0.33"
Flow Length=1,510'
Tc=28.9 min
CN=60
2.13 cfs
Type II 24-hr 1yr-24hr Rainfall=2.98"Preliminary Model
Printed 10/27/2017Prepared by Burton Engineering Associates, Inc
Page 24HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Summary for Subcatchment 2S: POST
[49] Hint: Tc<2dt may require smaller dt
Runoff = 21.23 cfs @ 11.95 hrs, Volume= 1.030 af, Depth= 2.14"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs
Type II 24-hr 1yr-24hr Rainfall=2.98"
Area (ac) CN Description
0.370 98 Water Surface, HSG B
4.530 98 Paved parking, HSG B
0.870 61 >75% Grass cover, Good, HSG B
5.770 92 Weighted Average
0.870 15.08% Pervious Area
4.900 84.92% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
Subcatchment 2S: POST
Runoff
Hydrograph
Time (hours)
12011511010510095908580757065605550454035302520151050Flow (cfs)23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Type II 24-hr
1yr-24hr Rainfall=2.98"
Runoff Area=5.770 ac
Runoff Volume=1.030 af
Runoff Depth=2.14"
Tc=5.0 min
CN=92
21.23 cfs
Type II 24-hr 1yr-24hr Rainfall=2.98"Preliminary Model
Printed 10/27/2017Prepared by Burton Engineering Associates, Inc
Page 25HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Summary for Subcatchment 6S: Post Residual
[49] Hint: Tc<2dt may require smaller dt
Runoff = 0.05 cfs @ 15.04 hrs, Volume= 0.038 af, Depth= 0.06"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs
Type II 24-hr 1yr-24hr Rainfall=2.98"
Area (sf) CN Description
354,143 48 Brush, Good, HSG B
354,143 100.00% Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
Subcatchment 6S: Post Residual
Runoff
Hydrograph
Time (hours)
12011511010510095908580757065605550454035302520151050Flow (cfs)0.05
0.045
0.04
0.035
0.03
0.025
0.02
0.015
0.01
0.005
0
Type II 24-hr
1yr-24hr Rainfall=2.98"
Runoff Area=354,143 sf
Runoff Volume=0.038 af
Runoff Depth=0.06"
Tc=5.0 min
CN=48
0.05 cfs
Type II 24-hr 1yr-24hr Rainfall=2.98"Preliminary Model
Printed 10/27/2017Prepared by Burton Engineering Associates, Inc
Page 26HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Summary for Reach 6R: Outlet Culvert
[52] Hint: Inlet/Outlet conditions not evaluated
Inflow Area = 5.770 ac, 84.92% Impervious, Inflow Depth = 2.14" for 1yr-24hr event
Inflow = 0.87 cfs @ 12.53 hrs, Volume= 1.030 af
Outflow = 0.87 cfs @ 12.53 hrs, Volume= 1.030 af, Atten= 0%, Lag= 0.0 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs
Max. Velocity= 5.70 fps, Min. Travel Time= 0.2 min
Avg. Velocity = 2.83 fps, Avg. Travel Time= 0.5 min
Peak Storage= 13 cf @ 12.53 hrs
Average Depth at Peak Storage= 0.19'
Bank-Full Depth= 2.00' Flow Area= 3.1 sf, Capacity= 46.04 cfs
24.0" Round Pipe
n= 0.012
Length= 85.0' Slope= 0.0353 '/'
Inlet Invert= 843.00', Outlet Invert= 840.00'
Reach 6R: Outlet Culvert
Inflow
Outflow
Hydrograph
Time (hours)
12011511010510095908580757065605550454035302520151050Flow (cfs)0.95
0.9
0.85
0.8
0.75
0.7
0.65
0.6
0.55
0.5
0.45
0.4
0.35
0.3
0.25
0.2
0.15
0.1
0.05
0
Inflow Area=5.770 ac
Avg. Flow Depth=0.19'
Max Vel=5.70 fps
24.0"
Round Pipe
n=0.012
L=85.0'
S=0.0353 '/'
Capacity=46.04 cfs
0.87 cfs0.87 cfs
Type II 24-hr 1yr-24hr Rainfall=2.98"Preliminary Model
Printed 10/27/2017Prepared by Burton Engineering Associates, Inc
Page 27HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Stage-Area-Storage for Reach 6R: Outlet Culvert
Elevation
(feet)
End-Area
(sq-ft)
Storage
(cubic-feet)
843.00 0.0 0
843.02 0.0 0
843.04 0.0 1
843.06 0.0 2
843.08 0.0 4
843.10 0.1 5
843.12 0.1 7
843.14 0.1 8
843.16 0.1 10
843.18 0.1 12
843.20 0.2 14
843.22 0.2 16
843.24 0.2 18
843.26 0.2 20
843.28 0.3 23
843.30 0.3 25
843.32 0.3 28
843.34 0.4 30
843.36 0.4 33
843.38 0.4 35
843.40 0.4 38
843.42 0.5 41
843.44 0.5 44
843.46 0.5 46
843.48 0.6 49
843.50 0.6 52
843.52 0.6 55
843.54 0.7 58
843.56 0.7 61
843.58 0.8 64
843.60 0.8 67
843.62 0.8 71
843.64 0.9 74
843.66 0.9 77
843.68 0.9 80
843.70 1.0 83
843.72 1.0 87
843.74 1.1 90
843.76 1.1 93
843.78 1.1 96
843.80 1.2 100
843.82 1.2 103
843.84 1.3 106
843.86 1.3 110
843.88 1.3 113
843.90 1.4 117
843.92 1.4 120
843.94 1.5 123
843.96 1.5 127
843.98 1.5 130
844.00 1.6 134
844.02 1.6 137
844.04 1.7 140
Elevation
(feet)
End-Area
(sq-ft)
Storage
(cubic-feet)
844.06 1.7 144
844.08 1.7 147
844.10 1.8 150
844.12 1.8 154
844.14 1.8 157
844.16 1.9 161
844.18 1.9 164
844.20 2.0 167
844.22 2.0 171
844.24 2.0 174
844.26 2.1 177
844.28 2.1 180
844.30 2.2 184
844.32 2.2 187
844.34 2.2 190
844.36 2.3 193
844.38 2.3 197
844.40 2.3 200
844.42 2.4 203
844.44 2.4 206
844.46 2.5 209
844.48 2.5 212
844.50 2.5 215
844.52 2.6 218
844.54 2.6 221
844.56 2.6 223
844.58 2.7 226
844.60 2.7 229
844.62 2.7 232
844.64 2.8 234
844.66 2.8 237
844.68 2.8 239
844.70 2.8 242
844.72 2.9 244
844.74 2.9 247
844.76 2.9 249
844.78 3.0 251
844.80 3.0 253
844.82 3.0 255
844.84 3.0 257
844.86 3.0 259
844.88 3.1 260
844.90 3.1 262
844.92 3.1 263
844.94 3.1 265
844.96 3.1 266
844.98 3.1 267
845.00 3.1 267
Type II 24-hr 1yr-24hr Rainfall=2.98"Preliminary Model
Printed 10/27/2017Prepared by Burton Engineering Associates, Inc
Page 28HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Summary for Pond 3P: Forebay
[90] Warning: Qout>Qin may require smaller dt or Finer Routing
Inflow Area = 5.770 ac, 84.92% Impervious, Inflow Depth = 2.14" for 1yr-24hr event
Inflow = 21.23 cfs @ 11.95 hrs, Volume= 1.030 af
Outflow = 21.84 cfs @ 11.97 hrs, Volume= 1.030 af, Atten= 0%, Lag= 0.8 min
Primary = 1.25 cfs @ 11.93 hrs, Volume= 0.698 af
Secondary = 20.59 cfs @ 11.97 hrs, Volume= 0.332 af
Routing by Dyn-Stor-Ind method, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs
Peak Elev= 848.47' @ 11.97 hrs Surf.Area= 5,510 sf Storage= 8,609 cf
Plug-Flow detention time= 201.6 min calculated for 1.030 af (100% of inflow)
Center-of-Mass det. time= 202.2 min ( 998.5 - 796.3 )
Volume Invert Avail.Storage Storage Description
#1 844.57' 29,501 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
844.57 0 0 0
845.00 575 124 124
846.00 1,350 963 1,086
847.00 2,446 1,898 2,984
848.00 4,207 3,327 6,311
849.00 6,961 5,584 11,895
850.00 8,723 7,842 19,737
851.00 10,805 9,764 29,501
Device Routing Invert Outlet Devices
#1 Primary 844.07'6.0" Round Culvert
L= 34.0' RCP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 844.07' / 843.90' S= 0.0050 '/' Cc= 0.900
n= 0.010, Flow Area= 0.20 sf
#2 Device 1 844.57'1.0" Vert. Orifice/Grate X 5.00 columns
X 6 rows with 1.0" cc spacing C= 0.600
#3 Secondary 848.20'60.0' long x 6.0' breadth Broad-Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00
2.50 3.00 3.50 4.00 4.50 5.00 5.50
Coef. (English) 2.37 2.51 2.70 2.68 2.68 2.67 2.65 2.65 2.65
2.65 2.66 2.66 2.67 2.69 2.72 2.76 2.83
#4 Primary 849.50'60.0' long x 6.0' breadth Broad-Crested Rectangular Weir X 0.00
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00
2.50 3.00 3.50 4.00 4.50 5.00 5.50
Coef. (English) 2.37 2.51 2.70 2.68 2.68 2.67 2.65 2.65 2.65
2.65 2.66 2.66 2.67 2.69 2.72 2.76 2.83
Type II 24-hr 1yr-24hr Rainfall=2.98"Preliminary Model
Printed 10/27/2017Prepared by Burton Engineering Associates, Inc
Page 29HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Primary OutFlow Max=1.23 cfs @ 11.93 hrs HW=848.44' TW=846.01' (Dynamic Tailwater)
1=Culvert (Passes 1.23 cfs of 1.40 cfs potential flow)
2=Orifice/Grate (Orifice Controls 1.23 cfs @ 7.51 fps)
4=Broad-Crested Rectangular Weir ( Controls 0.00 cfs)
Secondary OutFlow Max=19.31 cfs @ 11.97 hrs HW=848.46' TW=846.46' (Dynamic Tailwater)
3=Broad-Crested Rectangular Weir (Weir Controls 19.31 cfs @ 1.23 fps)
Pond 3P: Forebay
Inflow
Outflow
Primary
Secondary
Hydrograph
Time (hours)
12011511010510095908580757065605550454035302520151050Flow (cfs)24
22
20
18
16
14
12
10
8
6
4
2
0
Inflow Area=5.770 ac
Peak Elev=848.47'
Storage=8,609 cf
21.23 cfs21.84 cfs
1.25 cfs
20.59 cfs
Type II 24-hr 1yr-24hr Rainfall=2.98"Preliminary Model
Printed 10/27/2017Prepared by Burton Engineering Associates, Inc
Page 30HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Stage-Area-Storage for Pond 3P: Forebay
Elevation
(feet)
Surface
(sq-ft)
Storage
(cubic-feet)
844.57 0 0
844.67 134 7
844.77 267 27
844.87 401 60
844.97 535 107
845.07 629 166
845.17 707 233
845.27 784 307
845.37 862 389
845.47 939 479
845.57 1,017 577
845.67 1,094 683
845.77 1,172 796
845.87 1,249 917
845.97 1,327 1,046
846.07 1,427 1,183
846.17 1,536 1,331
846.27 1,646 1,491
846.37 1,756 1,661
846.47 1,865 1,842
846.57 1,975 2,034
846.67 2,084 2,237
846.77 2,194 2,451
846.87 2,304 2,675
846.97 2,413 2,911
847.07 2,569 3,160
847.17 2,745 3,425
847.27 2,921 3,709
847.37 3,098 4,010
847.47 3,274 4,328
847.57 3,450 4,664
847.67 3,626 5,018
847.77 3,802 5,390
847.87 3,978 5,779
847.97 4,154 6,185
848.07 4,400 6,612
848.17 4,675 7,066
848.27 4,951 7,547
848.37 5,226 8,056
848.47 5,501 8,592
848.57 5,777 9,156
848.67 6,052 9,747
848.77 6,328 10,366
848.87 6,603 11,013
848.97 6,878 11,687
849.07 7,084 12,386
849.17 7,261 13,103
849.27 7,437 13,838
849.37 7,613 14,591
849.47 7,789 15,361
849.57 7,965 16,149
849.67 8,142 16,954
849.77 8,318 17,777
Elevation
(feet)
Surface
(sq-ft)
Storage
(cubic-feet)
849.87 8,494 18,618
849.97 8,670 19,476
850.07 8,869 20,352
850.17 9,077 21,250
850.27 9,285 22,168
850.37 9,493 23,107
850.47 9,702 24,066
850.57 9,910 25,047
850.67 10,118 26,048
850.77 10,326 27,071
850.87 10,534 28,114
850.97 10,743 29,177
Type II 24-hr 1yr-24hr Rainfall=2.98"Preliminary Model
Printed 10/27/2017Prepared by Burton Engineering Associates, Inc
Page 31HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Summary for Pond 4P: Detention
Inflow = 20.59 cfs @ 11.97 hrs, Volume= 0.332 af
Outflow = 0.68 cfs @ 12.52 hrs, Volume= 0.332 af, Atten= 97%, Lag= 33.3 min
Primary = 0.68 cfs @ 12.52 hrs, Volume= 0.332 af
Secondary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af
Routing by Dyn-Stor-Ind method, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs
Peak Elev= 847.96' @ 12.52 hrs Surf.Area= 6,218 sf Storage= 12,808 cf
Plug-Flow detention time= 999.5 min calculated for 0.332 af (100% of inflow)
Center-of-Mass det. time= 999.0 min ( 1,723.4 - 724.5 )
Volume Invert Avail.Storage Storage Description
#1 845.00' 36,958 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
845.00 1,060 0 0
846.00 4,240 2,650 2,650
847.00 5,163 4,702 7,352
848.00 6,263 5,713 13,065
849.00 7,370 6,817 19,881
850.00 8,496 7,933 27,814
851.00 9,792 9,144 36,958
Device Routing Invert Outlet Devices
#1 Primary 842.10'24.0" Round Culvert
L= 84.0' CMP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 842.10' / 829.44' S= 0.1507 '/' Cc= 0.900
n= 0.022, Flow Area= 3.14 sf
#2 Device 1 845.00'1.5" Horiz. 1yr - Orifice C= 0.600 Limited to weir flow at low heads
#3 Device 1 847.60'10.0" W x 24.0" H Vert. 10yr - Orifice C= 0.600
#4 Device 1 849.60'36.0" W x 6.0" H Vert. 50yr - Orifice X 4.00 C= 0.600
#5 Secondary 850.00'60.0' long x 8.0' breadth Broad-Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00
2.50 3.00 3.50 4.00 4.50 5.00 5.50
Coef. (English) 2.43 2.54 2.70 2.69 2.68 2.68 2.66 2.64 2.64
2.64 2.65 2.65 2.66 2.66 2.68 2.70 2.74
Primary OutFlow Max=0.68 cfs @ 12.52 hrs HW=847.96' TW=843.19' (Dynamic Tailwater)
1=Culvert (Passes 0.68 cfs of 25.96 cfs potential flow)
2=1yr - Orifice (Orifice Controls 0.10 cfs @ 8.28 fps)
3=10yr - Orifice (Orifice Controls 0.57 cfs @ 1.92 fps)
4=50yr - Orifice ( Controls 0.00 cfs)
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=845.00' (Free Discharge)
5=Broad-Crested Rectangular Weir ( Controls 0.00 cfs)
Type II 24-hr 1yr-24hr Rainfall=2.98"Preliminary Model
Printed 10/27/2017Prepared by Burton Engineering Associates, Inc
Page 32HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Pond 4P: Detention
Inflow
Outflow
Primary
Secondary
Hydrograph
Time (hours)
12011511010510095908580757065605550454035302520151050Flow (cfs)23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Peak Elev=847.96'
Storage=12,808 cf
20.59 cfs
0.68 cfs0.68 cfs
0.00 cfs
Type II 24-hr 1yr-24hr Rainfall=2.98"Preliminary Model
Printed 10/27/2017Prepared by Burton Engineering Associates, Inc
Page 33HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Stage-Area-Storage for Pond 4P: Detention
Elevation
(feet)
Surface
(sq-ft)
Storage
(cubic-feet)
845.00 1,060 0
845.10 1,378 122
845.20 1,696 276
845.30 2,014 461
845.40 2,332 678
845.50 2,650 928
845.60 2,968 1,208
845.70 3,286 1,521
845.80 3,604 1,866
845.90 3,922 2,242
846.00 4,240 2,650
846.10 4,332 3,079
846.20 4,425 3,516
846.30 4,517 3,964
846.40 4,609 4,420
846.50 4,702 4,885
846.60 4,794 5,360
846.70 4,886 5,844
846.80 4,978 6,337
846.90 5,071 6,840
847.00 5,163 7,352
847.10 5,273 7,873
847.20 5,383 8,406
847.30 5,493 8,950
847.40 5,603 9,505
847.50 5,713 10,071
847.60 5,823 10,647
847.70 5,933 11,235
847.80 6,043 11,834
847.90 6,153 12,444
848.00 6,263 13,065
848.10 6,374 13,696
848.20 6,484 14,339
848.30 6,595 14,993
848.40 6,706 15,658
848.50 6,817 16,334
848.60 6,927 17,022
848.70 7,038 17,720
848.80 7,149 18,429
848.90 7,259 19,150
849.00 7,370 19,881
849.10 7,483 20,624
849.20 7,595 21,378
849.30 7,708 22,143
849.40 7,820 22,919
849.50 7,933 23,707
849.60 8,046 24,506
849.70 8,158 25,316
849.80 8,271 26,137
849.90 8,383 26,970
850.00 8,496 27,814
850.10 8,626 28,670
850.20 8,755 29,539
Elevation
(feet)
Surface
(sq-ft)
Storage
(cubic-feet)
850.30 8,885 30,421
850.40 9,014 31,316
850.50 9,144 32,224
850.60 9,274 33,145
850.70 9,403 34,079
850.80 9,533 35,026
850.90 9,662 35,985
851.00 9,792 36,958
Type II 24-hr 1yr-24hr Rainfall=2.98"Preliminary Model
Printed 10/27/2017Prepared by Burton Engineering Associates, Inc
Page 34HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Summary for Pond 5P: Sand Filter
Inflow Area = 5.770 ac, 84.92% Impervious, Inflow Depth = 1.45" for 1yr-24hr event
Inflow = 1.25 cfs @ 11.93 hrs, Volume= 0.698 af
Outflow = 0.26 cfs @ 19.50 hrs, Volume= 0.698 af, Atten= 79%, Lag= 453.9 min
Primary = 0.26 cfs @ 19.50 hrs, Volume= 0.698 af
Secondary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af
Routing by Dyn-Stor-Ind method, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs
Peak Elev= 848.08' @ 19.50 hrs Surf.Area= 4,490 sf Storage= 12,278 cf
Plug-Flow detention time= 631.3 min calculated for 0.698 af (100% of inflow)
Center-of-Mass det. time= 631.9 min ( 1,760.6 - 1,128.7 )
Volume Invert Avail.Storage Storage Description
#1 844.00' 29,322 cf Custom Stage Data (Prismatic) Listed below
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
844.00 1,705 0 0
845.00 2,268 1,987 1,987
846.00 2,911 2,590 4,576
847.00 3,627 3,269 7,845
848.00 4,417 4,022 11,867
849.00 5,279 4,848 16,715
850.00 6,213 5,746 22,461
851.00 7,509 6,861 29,322
Device Routing Invert Outlet Devices
#1 Primary 843.50'6.0" Round Culvert
L= 40.0' RCP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 843.50' / 842.90' S= 0.0150 '/' Cc= 0.900
n= 0.010 PVC, smooth interior, Flow Area= 0.20 sf
#2 Device 1 844.00'Special & User-Defined
Head (feet) 0.00 1.50 3.00 4.50 6.00
Disch. (cfs) 0.000 0.138 0.207 0.276 0.345
#3 Secondary 849.50'60.0' long x 6.0' breadth Broad-Crested Rectangular Weir X 0.00
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00
2.50 3.00 3.50 4.00 4.50 5.00 5.50
Coef. (English) 2.37 2.51 2.70 2.68 2.68 2.67 2.65 2.65 2.65
2.65 2.66 2.66 2.67 2.69 2.72 2.76 2.83
Primary OutFlow Max=0.26 cfs @ 19.50 hrs HW=848.08' TW=843.12' (Dynamic Tailwater)
1=Culvert (Passes 0.26 cfs of 1.86 cfs potential flow)
2=Special & User-Defined (Custom Controls 0.26 cfs)
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=844.00' TW=845.00' (Dynamic Tailwater)
3=Broad-Crested Rectangular Weir ( Controls 0.00 cfs)
Type II 24-hr 1yr-24hr Rainfall=2.98"Preliminary Model
Printed 10/27/2017Prepared by Burton Engineering Associates, Inc
Page 35HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Pond 5P: Sand Filter
Inflow
Outflow
Primary
Secondary
Hydrograph
Time (hours)
12011511010510095908580757065605550454035302520151050Flow (cfs)1
0
Inflow Area=5.770 ac
Peak Elev=848.08'
Storage=12,278 cf
1.25 cfs
0.26 cfs0.26 cfs
0.00 cfs
Type II 24-hr 1yr-24hr Rainfall=2.98"Preliminary Model
Printed 10/27/2017Prepared by Burton Engineering Associates, Inc
Page 36HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Stage-Area-Storage for Pond 5P: Sand Filter
Elevation
(feet)
Surface
(sq-ft)
Storage
(cubic-feet)
844.00 1,705 0
844.10 1,761 199
844.20 1,818 397
844.30 1,874 596
844.40 1,930 795
844.50 1,987 993
844.60 2,043 1,192
844.70 2,099 1,391
844.80 2,155 1,589
844.90 2,212 1,788
845.00 2,268 1,987
845.10 2,332 2,245
845.20 2,397 2,504
845.30 2,461 2,763
845.40 2,525 3,022
845.50 2,590 3,281
845.60 2,654 3,540
845.70 2,718 3,799
845.80 2,782 4,058
845.90 2,847 4,317
846.00 2,911 4,576
846.10 2,983 4,903
846.20 3,054 5,230
846.30 3,126 5,557
846.40 3,197 5,884
846.50 3,269 6,211
846.60 3,341 6,537
846.70 3,412 6,864
846.80 3,484 7,191
846.90 3,555 7,518
847.00 3,627 7,845
847.10 3,706 8,247
847.20 3,785 8,649
847.30 3,864 9,052
847.40 3,943 9,454
847.50 4,022 9,856
847.60 4,101 10,258
847.70 4,180 10,660
847.80 4,259 11,063
847.90 4,338 11,465
848.00 4,417 11,867
848.10 4,503 12,352
848.20 4,589 12,837
848.30 4,676 13,321
848.40 4,762 13,806
848.50 4,848 14,291
848.60 4,934 14,776
848.70 5,020 15,261
848.80 5,107 15,745
848.90 5,193 16,230
849.00 5,279 16,715
849.10 5,372 17,290
849.20 5,466 17,864
Elevation
(feet)
Surface
(sq-ft)
Storage
(cubic-feet)
849.30 5,559 18,439
849.40 5,653 19,013
849.50 5,746 19,588
849.60 5,839 20,163
849.70 5,933 20,737
849.80 6,026 21,312
849.90 6,120 21,886
850.00 6,213 22,461
850.10 6,343 23,147
850.20 6,472 23,833
850.30 6,602 24,519
850.40 6,731 25,205
850.50 6,861 25,892
850.60 6,991 26,578
850.70 7,120 27,264
850.80 7,250 27,950
850.90 7,379 28,636
851.00 7,509 29,322
Type II 24-hr 1yr-24hr Rainfall=2.98"Preliminary Model
Printed 10/27/2017Prepared by Burton Engineering Associates, Inc
Page 37HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Summary for Pond 7P: Analysis Point
[40] Hint: Not Described (Outflow=Inflow)
Inflow Area = 13.900 ac, 35.25% Impervious, Inflow Depth = 0.92" for 1yr-24hr event
Inflow = 0.87 cfs @ 12.56 hrs, Volume= 1.069 af
Primary = 0.87 cfs @ 12.56 hrs, Volume= 1.069 af, Atten= 0%, Lag= 0.0 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs
Pond 7P: Analysis Point
Inflow
Primary
Hydrograph
Time (hours)
12011511010510095908580757065605550454035302520151050Flow (cfs)0.95
0.9
0.85
0.8
0.75
0.7
0.65
0.6
0.55
0.5
0.45
0.4
0.35
0.3
0.25
0.2
0.15
0.1
0.05
0
Inflow Area=13.900 ac
0.87 cfs0.87 cfs

HYDROCAD OUTPUT 
10yr‐24hr Storm Event 

Type II 24-hr 10yr-24hr Rainfall=5.28"Preliminary Model
Printed 10/27/2017Prepared by Burton Engineering Associates, Inc
Page 38HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Time span=0.00-120.00 hrs, dt=0.05 hrs, 2401 points
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN
Reach routing by Dyn-Stor-Ind method - Pond routing by Dyn-Stor-Ind method
Runoff Area=13.900 ac 0.00% Impervious Runoff Depth=1.47"Subcatchment 1S: PRE
Flow Length=1,510' Tc=28.9 min CN=60 Runoff=16.19 cfs 1.700 af
Runoff Area=5.770 ac 84.92% Impervious Runoff Depth=4.36"Subcatchment 2S: POST
Tc=5.0 min CN=92 Runoff=41.32 cfs 2.098 af
Runoff Area=354,143 sf 0.00% Impervious Runoff Depth=0.69"Subcatchment 6S: Post Residual
Tc=5.0 min CN=48 Runoff=7.91 cfs 0.471 af
Avg. Flow Depth=0.55' Max Vel=10.81 fps Inflow=7.54 cfs 2.098 afReach 6R: Outlet Culvert
24.0" Round Pipe n=0.012 L=85.0' S=0.0353 '/' Capacity=46.04 cfs Outflow=7.53 cfs 2.098 af
Peak Elev=849.51' Storage=15,698 cf Inflow=41.32 cfs 2.098 afPond 3P: Forebay
Primary=1.19 cfs 0.772 af Secondary=40.84 cfs 1.326 af Outflow=41.80 cfs 2.098 af
Peak Elev=849.53' Storage=23,982 cf Inflow=40.84 cfs 1.326 afPond 4P: Detention
Primary=7.32 cfs 1.326 af Secondary=0.00 cfs 0.000 af Outflow=7.32 cfs 1.326 af
Peak Elev=848.14' Storage=12,531 cf Inflow=1.19 cfs 0.772 afPond 5P: Sand Filter
Primary=0.26 cfs 0.772 af Secondary=0.00 cfs 0.000 af Outflow=0.26 cfs 0.772 af
Inflow=14.65 cfs 2.569 afPond 7P: Analysis Point
Primary=14.65 cfs 2.569 af
Total Runoff Area = 27.800 ac Runoff Volume = 4.269 af Average Runoff Depth = 1.84"
82.37% Pervious = 22.900 ac 17.63% Impervious = 4.900 ac
Type II 24-hr 10yr-24hr Rainfall=5.28"Preliminary Model
Printed 10/27/2017Prepared by Burton Engineering Associates, Inc
Page 39HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Summary for Subcatchment 1S: PRE
Runoff = 16.19 cfs @ 12.26 hrs, Volume= 1.700 af, Depth= 1.47"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs
Type II 24-hr 10yr-24hr Rainfall=5.28"
Area (ac) CN Description
13.900 60 Woods, Fair, HSG B
13.900 100.00% Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
26.7 300 0.0900 0.19 Sheet Flow,
Woods: Light underbrush n= 0.400 P2= 3.61"
1.0 257 0.0733 4.36 Shallow Concentrated Flow,
Unpaved Kv= 16.1 fps
1.2 953 0.0100 13.39 1,311.77 Channel Flow,
Area= 98.0 sf Perim= 29.0' r= 3.38'
n= 0.025 Earth, clean & winding
28.9 1,510 Total
Subcatchment 1S: PRE
Runoff
Hydrograph
Time (hours)
12011511010510095908580757065605550454035302520151050Flow (cfs)18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Type II 24-hr
10yr-24hr Rainfall=5.28"
Runoff Area=13.900 ac
Runoff Volume=1.700 af
Runoff Depth=1.47"
Flow Length=1,510'
Tc=28.9 min
CN=60
16.19 cfs
Type II 24-hr 10yr-24hr Rainfall=5.28"Preliminary Model
Printed 10/27/2017Prepared by Burton Engineering Associates, Inc
Page 40HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Summary for Subcatchment 2S: POST
[49] Hint: Tc<2dt may require smaller dt
Runoff = 41.32 cfs @ 11.95 hrs, Volume= 2.098 af, Depth= 4.36"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs
Type II 24-hr 10yr-24hr Rainfall=5.28"
Area (ac) CN Description
0.370 98 Water Surface, HSG B
4.530 98 Paved parking, HSG B
0.870 61 >75% Grass cover, Good, HSG B
5.770 92 Weighted Average
0.870 15.08% Pervious Area
4.900 84.92% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
Subcatchment 2S: POST
Runoff
Hydrograph
Time (hours)
12011511010510095908580757065605550454035302520151050Flow (cfs)46
44
42
40
38
36
34
32
30
28
26
24
22
20
18
16
14
12
10
8
6
4
2
0
Type II 24-hr
10yr-24hr Rainfall=5.28"
Runoff Area=5.770 ac
Runoff Volume=2.098 af
Runoff Depth=4.36"
Tc=5.0 min
CN=92
41.32 cfs
Type II 24-hr 10yr-24hr Rainfall=5.28"Preliminary Model
Printed 10/27/2017Prepared by Burton Engineering Associates, Inc
Page 41HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Summary for Subcatchment 6S: Post Residual
[49] Hint: Tc<2dt may require smaller dt
Runoff = 7.91 cfs @ 11.99 hrs, Volume= 0.471 af, Depth= 0.69"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs
Type II 24-hr 10yr-24hr Rainfall=5.28"
Area (sf) CN Description
354,143 48 Brush, Good, HSG B
354,143 100.00% Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
Subcatchment 6S: Post Residual
Runoff
Hydrograph
Time (hours)
12011511010510095908580757065605550454035302520151050Flow (cfs)8
7
6
5
4
3
2
1
0
Type II 24-hr
10yr-24hr Rainfall=5.28"
Runoff Area=354,143 sf
Runoff Volume=0.471 af
Runoff Depth=0.69"
Tc=5.0 min
CN=48
7.91 cfs
Type II 24-hr 10yr-24hr Rainfall=5.28"Preliminary Model
Printed 10/27/2017Prepared by Burton Engineering Associates, Inc
Page 42HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Summary for Reach 6R: Outlet Culvert
[52] Hint: Inlet/Outlet conditions not evaluated
Inflow Area = 5.770 ac, 84.92% Impervious, Inflow Depth = 4.36" for 10yr-24hr event
Inflow = 7.54 cfs @ 12.10 hrs, Volume= 2.098 af
Outflow = 7.53 cfs @ 12.10 hrs, Volume= 2.098 af, Atten= 0%, Lag= 0.1 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs
Max. Velocity= 10.81 fps, Min. Travel Time= 0.1 min
Avg. Velocity = 3.19 fps, Avg. Travel Time= 0.4 min
Peak Storage= 59 cf @ 12.10 hrs
Average Depth at Peak Storage= 0.55'
Bank-Full Depth= 2.00' Flow Area= 3.1 sf, Capacity= 46.04 cfs
24.0" Round Pipe
n= 0.012
Length= 85.0' Slope= 0.0353 '/'
Inlet Invert= 843.00', Outlet Invert= 840.00'
Reach 6R: Outlet Culvert
Inflow
Outflow
Hydrograph
Time (hours)
12011511010510095908580757065605550454035302520151050Flow (cfs)8
7
6
5
4
3
2
1
0
Inflow Area=5.770 ac
Avg. Flow Depth=0.55'
Max Vel=10.81 fps
24.0"
Round Pipe
n=0.012
L=85.0'
S=0.0353 '/'
Capacity=46.04 cfs
7.54 cfs7.53 cfs
Type II 24-hr 10yr-24hr Rainfall=5.28"Preliminary Model
Printed 10/27/2017Prepared by Burton Engineering Associates, Inc
Page 43HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Stage-Area-Storage for Reach 6R: Outlet Culvert
Elevation
(feet)
End-Area
(sq-ft)
Storage
(cubic-feet)
843.00 0.0 0
843.02 0.0 0
843.04 0.0 1
843.06 0.0 2
843.08 0.0 4
843.10 0.1 5
843.12 0.1 7
843.14 0.1 8
843.16 0.1 10
843.18 0.1 12
843.20 0.2 14
843.22 0.2 16
843.24 0.2 18
843.26 0.2 20
843.28 0.3 23
843.30 0.3 25
843.32 0.3 28
843.34 0.4 30
843.36 0.4 33
843.38 0.4 35
843.40 0.4 38
843.42 0.5 41
843.44 0.5 44
843.46 0.5 46
843.48 0.6 49
843.50 0.6 52
843.52 0.6 55
843.54 0.7 58
843.56 0.7 61
843.58 0.8 64
843.60 0.8 67
843.62 0.8 71
843.64 0.9 74
843.66 0.9 77
843.68 0.9 80
843.70 1.0 83
843.72 1.0 87
843.74 1.1 90
843.76 1.1 93
843.78 1.1 96
843.80 1.2 100
843.82 1.2 103
843.84 1.3 106
843.86 1.3 110
843.88 1.3 113
843.90 1.4 117
843.92 1.4 120
843.94 1.5 123
843.96 1.5 127
843.98 1.5 130
844.00 1.6 134
844.02 1.6 137
844.04 1.7 140
Elevation
(feet)
End-Area
(sq-ft)
Storage
(cubic-feet)
844.06 1.7 144
844.08 1.7 147
844.10 1.8 150
844.12 1.8 154
844.14 1.8 157
844.16 1.9 161
844.18 1.9 164
844.20 2.0 167
844.22 2.0 171
844.24 2.0 174
844.26 2.1 177
844.28 2.1 180
844.30 2.2 184
844.32 2.2 187
844.34 2.2 190
844.36 2.3 193
844.38 2.3 197
844.40 2.3 200
844.42 2.4 203
844.44 2.4 206
844.46 2.5 209
844.48 2.5 212
844.50 2.5 215
844.52 2.6 218
844.54 2.6 221
844.56 2.6 223
844.58 2.7 226
844.60 2.7 229
844.62 2.7 232
844.64 2.8 234
844.66 2.8 237
844.68 2.8 239
844.70 2.8 242
844.72 2.9 244
844.74 2.9 247
844.76 2.9 249
844.78 3.0 251
844.80 3.0 253
844.82 3.0 255
844.84 3.0 257
844.86 3.0 259
844.88 3.1 260
844.90 3.1 262
844.92 3.1 263
844.94 3.1 265
844.96 3.1 266
844.98 3.1 267
845.00 3.1 267
Type II 24-hr 10yr-24hr Rainfall=5.28"Preliminary Model
Printed 10/27/2017Prepared by Burton Engineering Associates, Inc
Page 44HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Summary for Pond 3P: Forebay
[90] Warning: Qout>Qin may require smaller dt or Finer Routing
[87] Warning: Oscillations may require smaller dt or Finer Routing (severity=15)
Inflow Area = 5.770 ac, 84.92% Impervious, Inflow Depth = 4.36" for 10yr-24hr event
Inflow = 41.32 cfs @ 11.95 hrs, Volume= 2.098 af
Outflow = 41.80 cfs @ 11.94 hrs, Volume= 2.098 af, Atten= 0%, Lag= 0.0 min
Primary = 1.19 cfs @ 12.13 hrs, Volume= 0.772 af
Secondary = 40.84 cfs @ 11.93 hrs, Volume= 1.326 af
Routing by Dyn-Stor-Ind method, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs
Peak Elev= 849.51' @ 12.15 hrs Surf.Area= 7,865 sf Storage= 15,698 cf
Plug-Flow detention time= 115.7 min calculated for 2.097 af (100% of inflow)
Center-of-Mass det. time= 116.4 min ( 893.1 - 776.7 )
Volume Invert Avail.Storage Storage Description
#1 844.57' 29,501 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
844.57 0 0 0
845.00 575 124 124
846.00 1,350 963 1,086
847.00 2,446 1,898 2,984
848.00 4,207 3,327 6,311
849.00 6,961 5,584 11,895
850.00 8,723 7,842 19,737
851.00 10,805 9,764 29,501
Device Routing Invert Outlet Devices
#1 Primary 844.07'6.0" Round Culvert
L= 34.0' RCP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 844.07' / 843.90' S= 0.0050 '/' Cc= 0.900
n= 0.010, Flow Area= 0.20 sf
#2 Device 1 844.57'1.0" Vert. Orifice/Grate X 5.00 columns
X 6 rows with 1.0" cc spacing C= 0.600
#3 Secondary 848.20'60.0' long x 6.0' breadth Broad-Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00
2.50 3.00 3.50 4.00 4.50 5.00 5.50
Coef. (English) 2.37 2.51 2.70 2.68 2.68 2.67 2.65 2.65 2.65
2.65 2.66 2.66 2.67 2.69 2.72 2.76 2.83
#4 Primary 849.50'60.0' long x 6.0' breadth Broad-Crested Rectangular Weir X 0.00
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00
2.50 3.00 3.50 4.00 4.50 5.00 5.50
Coef. (English) 2.37 2.51 2.70 2.68 2.68 2.67 2.65 2.65 2.65
2.65 2.66 2.66 2.67 2.69 2.72 2.76 2.83
Type II 24-hr 10yr-24hr Rainfall=5.28"Preliminary Model
Printed 10/27/2017Prepared by Burton Engineering Associates, Inc
Page 45HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Primary OutFlow Max=1.18 cfs @ 12.13 hrs HW=849.49' TW=847.25' (Dynamic Tailwater)
1=Culvert (Passes 1.18 cfs of 1.34 cfs potential flow)
2=Orifice/Grate (Orifice Controls 1.18 cfs @ 7.21 fps)
4=Broad-Crested Rectangular Weir ( Controls 0.00 cfs)
Secondary OutFlow Max=0.00 cfs @ 11.93 hrs HW=848.59' TW=848.76' (Dynamic Tailwater)
3=Broad-Crested Rectangular Weir ( Controls 0.00 cfs)
Pond 3P: Forebay
Inflow
Outflow
Primary
Secondary
Hydrograph
Time (hours)
12011511010510095908580757065605550454035302520151050Flow (cfs)46
44
42
40
38
36
34
32
30
28
26
24
22
20
18
16
14
12
10
8
6
4
2
0
Inflow Area=5.770 ac
Peak Elev=849.51'
Storage=15,698 cf
41.32 cfs41.80 cfs
1.19 cfs
40.84 cfs
Type II 24-hr 10yr-24hr Rainfall=5.28"Preliminary Model
Printed 10/27/2017Prepared by Burton Engineering Associates, Inc
Page 46HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Stage-Area-Storage for Pond 3P: Forebay
Elevation
(feet)
Surface
(sq-ft)
Storage
(cubic-feet)
844.57 0 0
844.67 134 7
844.77 267 27
844.87 401 60
844.97 535 107
845.07 629 166
845.17 707 233
845.27 784 307
845.37 862 389
845.47 939 479
845.57 1,017 577
845.67 1,094 683
845.77 1,172 796
845.87 1,249 917
845.97 1,327 1,046
846.07 1,427 1,183
846.17 1,536 1,331
846.27 1,646 1,491
846.37 1,756 1,661
846.47 1,865 1,842
846.57 1,975 2,034
846.67 2,084 2,237
846.77 2,194 2,451
846.87 2,304 2,675
846.97 2,413 2,911
847.07 2,569 3,160
847.17 2,745 3,425
847.27 2,921 3,709
847.37 3,098 4,010
847.47 3,274 4,328
847.57 3,450 4,664
847.67 3,626 5,018
847.77 3,802 5,390
847.87 3,978 5,779
847.97 4,154 6,185
848.07 4,400 6,612
848.17 4,675 7,066
848.27 4,951 7,547
848.37 5,226 8,056
848.47 5,501 8,592
848.57 5,777 9,156
848.67 6,052 9,747
848.77 6,328 10,366
848.87 6,603 11,013
848.97 6,878 11,687
849.07 7,084 12,386
849.17 7,261 13,103
849.27 7,437 13,838
849.37 7,613 14,591
849.47 7,789 15,361
849.57 7,965 16,149
849.67 8,142 16,954
849.77 8,318 17,777
Elevation
(feet)
Surface
(sq-ft)
Storage
(cubic-feet)
849.87 8,494 18,618
849.97 8,670 19,476
850.07 8,869 20,352
850.17 9,077 21,250
850.27 9,285 22,168
850.37 9,493 23,107
850.47 9,702 24,066
850.57 9,910 25,047
850.67 10,118 26,048
850.77 10,326 27,071
850.87 10,534 28,114
850.97 10,743 29,177
Type II 24-hr 10yr-24hr Rainfall=5.28"Preliminary Model
Printed 10/27/2017Prepared by Burton Engineering Associates, Inc
Page 47HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Summary for Pond 4P: Detention
[80] Warning: Exceeded Pond 3P by 0.40' @ 11.95 hrs (98.71 cfs 3.427 af)
Inflow = 40.84 cfs @ 11.93 hrs, Volume= 1.326 af
Outflow = 7.32 cfs @ 12.10 hrs, Volume= 1.326 af, Atten= 82%, Lag= 9.9 min
Primary = 7.32 cfs @ 12.10 hrs, Volume= 1.326 af
Secondary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af
Routing by Dyn-Stor-Ind method, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs
Peak Elev= 849.53' @ 12.10 hrs Surf.Area= 7,972 sf Storage= 23,982 cf
Plug-Flow detention time= 379.7 min calculated for 1.325 af (100% of inflow)
Center-of-Mass det. time= 380.8 min ( 1,169.5 - 788.7 )
Volume Invert Avail.Storage Storage Description
#1 845.00' 36,958 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
845.00 1,060 0 0
846.00 4,240 2,650 2,650
847.00 5,163 4,702 7,352
848.00 6,263 5,713 13,065
849.00 7,370 6,817 19,881
850.00 8,496 7,933 27,814
851.00 9,792 9,144 36,958
Device Routing Invert Outlet Devices
#1 Primary 842.10'24.0" Round Culvert
L= 84.0' CMP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 842.10' / 829.44' S= 0.1507 '/' Cc= 0.900
n= 0.022, Flow Area= 3.14 sf
#2 Device 1 845.00'1.5" Horiz. 1yr - Orifice C= 0.600 Limited to weir flow at low heads
#3 Device 1 847.60'10.0" W x 24.0" H Vert. 10yr - Orifice C= 0.600
#4 Device 1 849.60'36.0" W x 6.0" H Vert. 50yr - Orifice X 4.00 C= 0.600
#5 Secondary 850.00'60.0' long x 8.0' breadth Broad-Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00
2.50 3.00 3.50 4.00 4.50 5.00 5.50
Coef. (English) 2.43 2.54 2.70 2.69 2.68 2.68 2.66 2.64 2.64
2.64 2.65 2.65 2.66 2.66 2.68 2.70 2.74
Primary OutFlow Max=7.32 cfs @ 12.10 hrs HW=849.53' TW=843.55' (Dynamic Tailwater)
1=Culvert (Passes 7.32 cfs of 29.09 cfs potential flow)
2=1yr - Orifice (Orifice Controls 0.13 cfs @ 10.25 fps)
3=10yr - Orifice (Orifice Controls 7.19 cfs @ 4.46 fps)
4=50yr - Orifice ( Controls 0.00 cfs)
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=845.00' (Free Discharge)
5=Broad-Crested Rectangular Weir ( Controls 0.00 cfs)
Type II 24-hr 10yr-24hr Rainfall=5.28"Preliminary Model
Printed 10/27/2017Prepared by Burton Engineering Associates, Inc
Page 48HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Pond 4P: Detention
Inflow
Outflow
Primary
Secondary
Hydrograph
Time (hours)
12011511010510095908580757065605550454035302520151050Flow (cfs)44
42
40
38
36
34
32
30
28
26
24
22
20
18
16
14
12
10
8
6
4
2
0
Peak Elev=849.53'
Storage=23,982 cf
40.84 cfs
7.32 cfs7.32 cfs
0.00 cfs
Type II 24-hr 10yr-24hr Rainfall=5.28"Preliminary Model
Printed 10/27/2017Prepared by Burton Engineering Associates, Inc
Page 49HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Stage-Area-Storage for Pond 4P: Detention
Elevation
(feet)
Surface
(sq-ft)
Storage
(cubic-feet)
845.00 1,060 0
845.10 1,378 122
845.20 1,696 276
845.30 2,014 461
845.40 2,332 678
845.50 2,650 928
845.60 2,968 1,208
845.70 3,286 1,521
845.80 3,604 1,866
845.90 3,922 2,242
846.00 4,240 2,650
846.10 4,332 3,079
846.20 4,425 3,516
846.30 4,517 3,964
846.40 4,609 4,420
846.50 4,702 4,885
846.60 4,794 5,360
846.70 4,886 5,844
846.80 4,978 6,337
846.90 5,071 6,840
847.00 5,163 7,352
847.10 5,273 7,873
847.20 5,383 8,406
847.30 5,493 8,950
847.40 5,603 9,505
847.50 5,713 10,071
847.60 5,823 10,647
847.70 5,933 11,235
847.80 6,043 11,834
847.90 6,153 12,444
848.00 6,263 13,065
848.10 6,374 13,696
848.20 6,484 14,339
848.30 6,595 14,993
848.40 6,706 15,658
848.50 6,817 16,334
848.60 6,927 17,022
848.70 7,038 17,720
848.80 7,149 18,429
848.90 7,259 19,150
849.00 7,370 19,881
849.10 7,483 20,624
849.20 7,595 21,378
849.30 7,708 22,143
849.40 7,820 22,919
849.50 7,933 23,707
849.60 8,046 24,506
849.70 8,158 25,316
849.80 8,271 26,137
849.90 8,383 26,970
850.00 8,496 27,814
850.10 8,626 28,670
850.20 8,755 29,539
Elevation
(feet)
Surface
(sq-ft)
Storage
(cubic-feet)
850.30 8,885 30,421
850.40 9,014 31,316
850.50 9,144 32,224
850.60 9,274 33,145
850.70 9,403 34,079
850.80 9,533 35,026
850.90 9,662 35,985
851.00 9,792 36,958
Type II 24-hr 10yr-24hr Rainfall=5.28"Preliminary Model
Printed 10/27/2017Prepared by Burton Engineering Associates, Inc
Page 50HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Summary for Pond 5P: Sand Filter
Inflow Area = 5.770 ac, 84.92% Impervious, Inflow Depth = 1.61" for 10yr-24hr event
Inflow = 1.19 cfs @ 12.13 hrs, Volume= 0.772 af
Outflow = 0.26 cfs @ 14.45 hrs, Volume= 0.772 af, Atten= 78%, Lag= 139.5 min
Primary = 0.26 cfs @ 14.45 hrs, Volume= 0.772 af
Secondary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af
Routing by Dyn-Stor-Ind method, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs
Peak Elev= 848.14' @ 14.45 hrs Surf.Area= 4,535 sf Storage= 12,531 cf
Plug-Flow detention time= 643.4 min calculated for 0.772 af (100% of inflow)
Center-of-Mass det. time= 644.0 min ( 1,716.4 - 1,072.4 )
Volume Invert Avail.Storage Storage Description
#1 844.00' 29,322 cf Custom Stage Data (Prismatic) Listed below
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
844.00 1,705 0 0
845.00 2,268 1,987 1,987
846.00 2,911 2,590 4,576
847.00 3,627 3,269 7,845
848.00 4,417 4,022 11,867
849.00 5,279 4,848 16,715
850.00 6,213 5,746 22,461
851.00 7,509 6,861 29,322
Device Routing Invert Outlet Devices
#1 Primary 843.50'6.0" Round Culvert
L= 40.0' RCP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 843.50' / 842.90' S= 0.0150 '/' Cc= 0.900
n= 0.010 PVC, smooth interior, Flow Area= 0.20 sf
#2 Device 1 844.00'Special & User-Defined
Head (feet) 0.00 1.50 3.00 4.50 6.00
Disch. (cfs) 0.000 0.138 0.207 0.276 0.345
#3 Secondary 849.50'60.0' long x 6.0' breadth Broad-Crested Rectangular Weir X 0.00
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00
2.50 3.00 3.50 4.00 4.50 5.00 5.50
Coef. (English) 2.37 2.51 2.70 2.68 2.68 2.67 2.65 2.65 2.65
2.65 2.66 2.66 2.67 2.69 2.72 2.76 2.83
Primary OutFlow Max=0.26 cfs @ 14.45 hrs HW=848.14' TW=843.26' (Dynamic Tailwater)
1=Culvert (Passes 0.26 cfs of 1.87 cfs potential flow)
2=Special & User-Defined (Custom Controls 0.26 cfs)
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=844.00' TW=845.00' (Dynamic Tailwater)
3=Broad-Crested Rectangular Weir ( Controls 0.00 cfs)
Type II 24-hr 10yr-24hr Rainfall=5.28"Preliminary Model
Printed 10/27/2017Prepared by Burton Engineering Associates, Inc
Page 51HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Pond 5P: Sand Filter
Inflow
Outflow
Primary
Secondary
Hydrograph
Time (hours)
12011511010510095908580757065605550454035302520151050Flow (cfs)1
0
Inflow Area=5.770 ac
Peak Elev=848.14'
Storage=12,531 cf
1.19 cfs
0.26 cfs0.26 cfs
0.00 cfs
Type II 24-hr 10yr-24hr Rainfall=5.28"Preliminary Model
Printed 10/27/2017Prepared by Burton Engineering Associates, Inc
Page 52HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Stage-Area-Storage for Pond 5P: Sand Filter
Elevation
(feet)
Surface
(sq-ft)
Storage
(cubic-feet)
844.00 1,705 0
844.10 1,761 199
844.20 1,818 397
844.30 1,874 596
844.40 1,930 795
844.50 1,987 993
844.60 2,043 1,192
844.70 2,099 1,391
844.80 2,155 1,589
844.90 2,212 1,788
845.00 2,268 1,987
845.10 2,332 2,245
845.20 2,397 2,504
845.30 2,461 2,763
845.40 2,525 3,022
845.50 2,590 3,281
845.60 2,654 3,540
845.70 2,718 3,799
845.80 2,782 4,058
845.90 2,847 4,317
846.00 2,911 4,576
846.10 2,983 4,903
846.20 3,054 5,230
846.30 3,126 5,557
846.40 3,197 5,884
846.50 3,269 6,211
846.60 3,341 6,537
846.70 3,412 6,864
846.80 3,484 7,191
846.90 3,555 7,518
847.00 3,627 7,845
847.10 3,706 8,247
847.20 3,785 8,649
847.30 3,864 9,052
847.40 3,943 9,454
847.50 4,022 9,856
847.60 4,101 10,258
847.70 4,180 10,660
847.80 4,259 11,063
847.90 4,338 11,465
848.00 4,417 11,867
848.10 4,503 12,352
848.20 4,589 12,837
848.30 4,676 13,321
848.40 4,762 13,806
848.50 4,848 14,291
848.60 4,934 14,776
848.70 5,020 15,261
848.80 5,107 15,745
848.90 5,193 16,230
849.00 5,279 16,715
849.10 5,372 17,290
849.20 5,466 17,864
Elevation
(feet)
Surface
(sq-ft)
Storage
(cubic-feet)
849.30 5,559 18,439
849.40 5,653 19,013
849.50 5,746 19,588
849.60 5,839 20,163
849.70 5,933 20,737
849.80 6,026 21,312
849.90 6,120 21,886
850.00 6,213 22,461
850.10 6,343 23,147
850.20 6,472 23,833
850.30 6,602 24,519
850.40 6,731 25,205
850.50 6,861 25,892
850.60 6,991 26,578
850.70 7,120 27,264
850.80 7,250 27,950
850.90 7,379 28,636
851.00 7,509 29,322
Type II 24-hr 10yr-24hr Rainfall=5.28"Preliminary Model
Printed 10/27/2017Prepared by Burton Engineering Associates, Inc
Page 53HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Summary for Pond 7P: Analysis Point
[40] Hint: Not Described (Outflow=Inflow)
Inflow Area = 13.900 ac, 35.25% Impervious, Inflow Depth = 2.22" for 10yr-24hr event
Inflow = 14.65 cfs @ 12.00 hrs, Volume= 2.569 af
Primary = 14.65 cfs @ 12.00 hrs, Volume= 2.569 af, Atten= 0%, Lag= 0.0 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs
Pond 7P: Analysis Point
Inflow
Primary
Hydrograph
Time (hours)
12011511010510095908580757065605550454035302520151050Flow (cfs)16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Inflow Area=13.900 ac
14.65 cfs14.65 cfs

HYDROCAD OUTPUT 
50yr‐24hr Storm Event 

Type II 24-hr 50yr-24hr Rainfall=7.10"Preliminary Model
Printed 10/27/2017Prepared by Burton Engineering Associates, Inc
Page 54HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Time span=0.00-120.00 hrs, dt=0.05 hrs, 2401 points
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN
Reach routing by Dyn-Stor-Ind method - Pond routing by Dyn-Stor-Ind method
Runoff Area=13.900 ac 0.00% Impervious Runoff Depth=2.67"Subcatchment 1S: PRE
Flow Length=1,510' Tc=28.9 min CN=60 Runoff=31.66 cfs 3.098 af
Runoff Area=5.770 ac 84.92% Impervious Runoff Depth=6.15"Subcatchment 2S: POST
Tc=5.0 min CN=92 Runoff=56.98 cfs 2.959 af
Runoff Area=354,143 sf 0.00% Impervious Runoff Depth=1.54"Subcatchment 6S: Post Residual
Tc=5.0 min CN=48 Runoff=20.94 cfs 1.046 af
Avg. Flow Depth=1.03' Max Vel=14.74 fps Inflow=24.31 cfs 2.928 afReach 6R: Outlet Culvert
24.0" Round Pipe n=0.012 L=85.0' S=0.0353 '/' Capacity=46.04 cfs Outflow=24.32 cfs 2.928 af
Peak Elev=850.12' Storage=20,788 cf Inflow=56.98 cfs 2.959 afPond 3P: Forebay
Primary=1.23 cfs 0.803 af Secondary=39.24 cfs 2.156 af Outflow=40.32 cfs 2.959 af
Peak Elev=850.12' Storage=28,826 cf Inflow=39.24 cfs 2.156 afPond 4P: Detention
Primary=24.07 cfs 2.125 af Secondary=4.81 cfs 0.031 af Outflow=28.83 cfs 2.156 af
Peak Elev=848.44' Storage=14,010 cf Inflow=1.23 cfs 0.803 afPond 5P: Sand Filter
Primary=0.27 cfs 0.803 af Secondary=0.00 cfs 0.000 af Outflow=0.27 cfs 0.803 af
Inflow=43.43 cfs 3.974 afPond 7P: Analysis Point
Primary=43.43 cfs 3.974 af
Total Runoff Area = 27.800 ac Runoff Volume = 7.103 af Average Runoff Depth = 3.07"
82.37% Pervious = 22.900 ac 17.63% Impervious = 4.900 ac
Type II 24-hr 50yr-24hr Rainfall=7.10"Preliminary Model
Printed 10/27/2017Prepared by Burton Engineering Associates, Inc
Page 55HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Summary for Subcatchment 1S: PRE
Runoff = 31.66 cfs @ 12.25 hrs, Volume= 3.098 af, Depth= 2.67"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs
Type II 24-hr 50yr-24hr Rainfall=7.10"
Area (ac) CN Description
13.900 60 Woods, Fair, HSG B
13.900 100.00% Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
26.7 300 0.0900 0.19 Sheet Flow,
Woods: Light underbrush n= 0.400 P2= 3.61"
1.0 257 0.0733 4.36 Shallow Concentrated Flow,
Unpaved Kv= 16.1 fps
1.2 953 0.0100 13.39 1,311.77 Channel Flow,
Area= 98.0 sf Perim= 29.0' r= 3.38'
n= 0.025 Earth, clean & winding
28.9 1,510 Total
Subcatchment 1S: PRE
Runoff
Hydrograph
Time (hours)
12011511010510095908580757065605550454035302520151050Flow (cfs)34
32
30
28
26
24
22
20
18
16
14
12
10
8
6
4
2
0
Type II 24-hr
50yr-24hr Rainfall=7.10"
Runoff Area=13.900 ac
Runoff Volume=3.098 af
Runoff Depth=2.67"
Flow Length=1,510'
Tc=28.9 min
CN=60
31.66 cfs
Type II 24-hr 50yr-24hr Rainfall=7.10"Preliminary Model
Printed 10/27/2017Prepared by Burton Engineering Associates, Inc
Page 56HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Summary for Subcatchment 2S: POST
[49] Hint: Tc<2dt may require smaller dt
Runoff = 56.98 cfs @ 11.95 hrs, Volume= 2.959 af, Depth= 6.15"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs
Type II 24-hr 50yr-24hr Rainfall=7.10"
Area (ac) CN Description
0.370 98 Water Surface, HSG B
4.530 98 Paved parking, HSG B
0.870 61 >75% Grass cover, Good, HSG B
5.770 92 Weighted Average
0.870 15.08% Pervious Area
4.900 84.92% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
Subcatchment 2S: POST
Runoff
Hydrograph
Time (hours)
12011511010510095908580757065605550454035302520151050Flow (cfs)60
55
50
45
40
35
30
25
20
15
10
5
0
Type II 24-hr
50yr-24hr Rainfall=7.10"
Runoff Area=5.770 ac
Runoff Volume=2.959 af
Runoff Depth=6.15"
Tc=5.0 min
CN=92
56.98 cfs
Type II 24-hr 50yr-24hr Rainfall=7.10"Preliminary Model
Printed 10/27/2017Prepared by Burton Engineering Associates, Inc
Page 57HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Summary for Subcatchment 6S: Post Residual
[49] Hint: Tc<2dt may require smaller dt
Runoff = 20.94 cfs @ 11.97 hrs, Volume= 1.046 af, Depth= 1.54"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs
Type II 24-hr 50yr-24hr Rainfall=7.10"
Area (sf) CN Description
354,143 48 Brush, Good, HSG B
354,143 100.00% Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
Subcatchment 6S: Post Residual
Runoff
Hydrograph
Time (hours)
12011511010510095908580757065605550454035302520151050Flow (cfs)23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Type II 24-hr
50yr-24hr Rainfall=7.10"
Runoff Area=354,143 sf
Runoff Volume=1.046 af
Runoff Depth=1.54"
Tc=5.0 min
CN=48
20.94 cfs
Type II 24-hr 50yr-24hr Rainfall=7.10"Preliminary Model
Printed 10/27/2017Prepared by Burton Engineering Associates, Inc
Page 58HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Summary for Reach 6R: Outlet Culvert
[52] Hint: Inlet/Outlet conditions not evaluated
[90] Warning: Qout>Qin may require smaller dt or Finer Routing
Inflow Area = 5.770 ac, 84.92% Impervious, Inflow Depth = 6.09" for 50yr-24hr event
Inflow = 24.31 cfs @ 12.02 hrs, Volume= 2.928 af
Outflow = 24.32 cfs @ 12.02 hrs, Volume= 2.928 af, Atten= 0%, Lag= 0.1 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs
Max. Velocity= 14.74 fps, Min. Travel Time= 0.1 min
Avg. Velocity = 3.32 fps, Avg. Travel Time= 0.4 min
Peak Storage= 139 cf @ 12.02 hrs
Average Depth at Peak Storage= 1.03'
Bank-Full Depth= 2.00' Flow Area= 3.1 sf, Capacity= 46.04 cfs
24.0" Round Pipe
n= 0.012
Length= 85.0' Slope= 0.0353 '/'
Inlet Invert= 843.00', Outlet Invert= 840.00'
Type II 24-hr 50yr-24hr Rainfall=7.10"Preliminary Model
Printed 10/27/2017Prepared by Burton Engineering Associates, Inc
Page 59HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Reach 6R: Outlet Culvert
Inflow
Outflow
Hydrograph
Time (hours)
12011511010510095908580757065605550454035302520151050Flow (cfs)26
24
22
20
18
16
14
12
10
8
6
4
2
0
Inflow Area=5.770 ac
Avg. Flow Depth=1.03'
Max Vel=14.74 fps
24.0"
Round Pipe
n=0.012
L=85.0'
S=0.0353 '/'
Capacity=46.04 cfs
24.31 cfs24.32 cfs
Type II 24-hr 50yr-24hr Rainfall=7.10"Preliminary Model
Printed 10/27/2017Prepared by Burton Engineering Associates, Inc
Page 60HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Stage-Area-Storage for Reach 6R: Outlet Culvert
Elevation
(feet)
End-Area
(sq-ft)
Storage
(cubic-feet)
843.00 0.0 0
843.02 0.0 0
843.04 0.0 1
843.06 0.0 2
843.08 0.0 4
843.10 0.1 5
843.12 0.1 7
843.14 0.1 8
843.16 0.1 10
843.18 0.1 12
843.20 0.2 14
843.22 0.2 16
843.24 0.2 18
843.26 0.2 20
843.28 0.3 23
843.30 0.3 25
843.32 0.3 28
843.34 0.4 30
843.36 0.4 33
843.38 0.4 35
843.40 0.4 38
843.42 0.5 41
843.44 0.5 44
843.46 0.5 46
843.48 0.6 49
843.50 0.6 52
843.52 0.6 55
843.54 0.7 58
843.56 0.7 61
843.58 0.8 64
843.60 0.8 67
843.62 0.8 71
843.64 0.9 74
843.66 0.9 77
843.68 0.9 80
843.70 1.0 83
843.72 1.0 87
843.74 1.1 90
843.76 1.1 93
843.78 1.1 96
843.80 1.2 100
843.82 1.2 103
843.84 1.3 106
843.86 1.3 110
843.88 1.3 113
843.90 1.4 117
843.92 1.4 120
843.94 1.5 123
843.96 1.5 127
843.98 1.5 130
844.00 1.6 134
844.02 1.6 137
844.04 1.7 140
Elevation
(feet)
End-Area
(sq-ft)
Storage
(cubic-feet)
844.06 1.7 144
844.08 1.7 147
844.10 1.8 150
844.12 1.8 154
844.14 1.8 157
844.16 1.9 161
844.18 1.9 164
844.20 2.0 167
844.22 2.0 171
844.24 2.0 174
844.26 2.1 177
844.28 2.1 180
844.30 2.2 184
844.32 2.2 187
844.34 2.2 190
844.36 2.3 193
844.38 2.3 197
844.40 2.3 200
844.42 2.4 203
844.44 2.4 206
844.46 2.5 209
844.48 2.5 212
844.50 2.5 215
844.52 2.6 218
844.54 2.6 221
844.56 2.6 223
844.58 2.7 226
844.60 2.7 229
844.62 2.7 232
844.64 2.8 234
844.66 2.8 237
844.68 2.8 239
844.70 2.8 242
844.72 2.9 244
844.74 2.9 247
844.76 2.9 249
844.78 3.0 251
844.80 3.0 253
844.82 3.0 255
844.84 3.0 257
844.86 3.0 259
844.88 3.1 260
844.90 3.1 262
844.92 3.1 263
844.94 3.1 265
844.96 3.1 266
844.98 3.1 267
845.00 3.1 267
Type II 24-hr 50yr-24hr Rainfall=7.10"Preliminary Model
Printed 10/27/2017Prepared by Burton Engineering Associates, Inc
Page 61HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Summary for Pond 3P: Forebay
[87] Warning: Oscillations may require smaller dt or Finer Routing (severity=18)
Inflow Area = 5.770 ac, 84.92% Impervious, Inflow Depth = 6.15" for 50yr-24hr event
Inflow = 56.98 cfs @ 11.95 hrs, Volume= 2.959 af
Outflow = 40.32 cfs @ 11.95 hrs, Volume= 2.959 af, Atten= 29%, Lag= 0.0 min
Primary = 1.23 cfs @ 12.06 hrs, Volume= 0.803 af
Secondary = 39.24 cfs @ 11.95 hrs, Volume= 2.156 af
Routing by Dyn-Stor-Ind method, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs
Peak Elev= 850.12' @ 12.07 hrs Surf.Area= 8,970 sf Storage= 20,788 cf
Plug-Flow detention time= 88.8 min calculated for 2.958 af (100% of inflow)
Center-of-Mass det. time= 89.4 min ( 857.3 - 767.9 )
Volume Invert Avail.Storage Storage Description
#1 844.57' 29,501 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
844.57 0 0 0
845.00 575 124 124
846.00 1,350 963 1,086
847.00 2,446 1,898 2,984
848.00 4,207 3,327 6,311
849.00 6,961 5,584 11,895
850.00 8,723 7,842 19,737
851.00 10,805 9,764 29,501
Device Routing Invert Outlet Devices
#1 Primary 844.07'6.0" Round Culvert
L= 34.0' RCP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 844.07' / 843.90' S= 0.0050 '/' Cc= 0.900
n= 0.010, Flow Area= 0.20 sf
#2 Device 1 844.57'1.0" Vert. Orifice/Grate X 5.00 columns
X 6 rows with 1.0" cc spacing C= 0.600
#3 Secondary 848.20'60.0' long x 6.0' breadth Broad-Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00
2.50 3.00 3.50 4.00 4.50 5.00 5.50
Coef. (English) 2.37 2.51 2.70 2.68 2.68 2.67 2.65 2.65 2.65
2.65 2.66 2.66 2.67 2.69 2.72 2.76 2.83
#4 Primary 849.50'60.0' long x 6.0' breadth Broad-Crested Rectangular Weir X 0.00
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00
2.50 3.00 3.50 4.00 4.50 5.00 5.50
Coef. (English) 2.37 2.51 2.70 2.68 2.68 2.67 2.65 2.65 2.65
2.65 2.66 2.66 2.67 2.69 2.72 2.76 2.83
Type II 24-hr 50yr-24hr Rainfall=7.10"Preliminary Model
Printed 10/27/2017Prepared by Burton Engineering Associates, Inc
Page 62HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Primary OutFlow Max=1.21 cfs @ 12.06 hrs HW=850.10' TW=847.73' (Dynamic Tailwater)
1=Culvert (Passes 1.21 cfs of 1.38 cfs potential flow)
2=Orifice/Grate (Orifice Controls 1.21 cfs @ 7.41 fps)
4=Broad-Crested Rectangular Weir ( Controls 0.00 cfs)
Secondary OutFlow Max=0.00 cfs @ 11.95 hrs HW=849.46' TW=849.89' (Dynamic Tailwater)
3=Broad-Crested Rectangular Weir ( Controls 0.00 cfs)
Pond 3P: Forebay
Inflow
Outflow
Primary
Secondary
Hydrograph
Time (hours)
12011511010510095908580757065605550454035302520151050Flow (cfs)60
55
50
45
40
35
30
25
20
15
10
5
0
Inflow Area=5.770 ac
Peak Elev=850.12'
Storage=20,788 cf
56.98 cfs
40.32 cfs
1.23 cfs
39.24 cfs
Type II 24-hr 50yr-24hr Rainfall=7.10"Preliminary Model
Printed 10/27/2017Prepared by Burton Engineering Associates, Inc
Page 63HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Stage-Area-Storage for Pond 3P: Forebay
Elevation
(feet)
Surface
(sq-ft)
Storage
(cubic-feet)
844.57 0 0
844.67 134 7
844.77 267 27
844.87 401 60
844.97 535 107
845.07 629 166
845.17 707 233
845.27 784 307
845.37 862 389
845.47 939 479
845.57 1,017 577
845.67 1,094 683
845.77 1,172 796
845.87 1,249 917
845.97 1,327 1,046
846.07 1,427 1,183
846.17 1,536 1,331
846.27 1,646 1,491
846.37 1,756 1,661
846.47 1,865 1,842
846.57 1,975 2,034
846.67 2,084 2,237
846.77 2,194 2,451
846.87 2,304 2,675
846.97 2,413 2,911
847.07 2,569 3,160
847.17 2,745 3,425
847.27 2,921 3,709
847.37 3,098 4,010
847.47 3,274 4,328
847.57 3,450 4,664
847.67 3,626 5,018
847.77 3,802 5,390
847.87 3,978 5,779
847.97 4,154 6,185
848.07 4,400 6,612
848.17 4,675 7,066
848.27 4,951 7,547
848.37 5,226 8,056
848.47 5,501 8,592
848.57 5,777 9,156
848.67 6,052 9,747
848.77 6,328 10,366
848.87 6,603 11,013
848.97 6,878 11,687
849.07 7,084 12,386
849.17 7,261 13,103
849.27 7,437 13,838
849.37 7,613 14,591
849.47 7,789 15,361
849.57 7,965 16,149
849.67 8,142 16,954
849.77 8,318 17,777
Elevation
(feet)
Surface
(sq-ft)
Storage
(cubic-feet)
849.87 8,494 18,618
849.97 8,670 19,476
850.07 8,869 20,352
850.17 9,077 21,250
850.27 9,285 22,168
850.37 9,493 23,107
850.47 9,702 24,066
850.57 9,910 25,047
850.67 10,118 26,048
850.77 10,326 27,071
850.87 10,534 28,114
850.97 10,743 29,177
Type II 24-hr 50yr-24hr Rainfall=7.10"Preliminary Model
Printed 10/27/2017Prepared by Burton Engineering Associates, Inc
Page 64HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Summary for Pond 4P: Detention
[80] Warning: Exceeded Pond 3P by 0.49' @ 11.90 hrs (173.55 cfs 4.776 af)
Inflow = 39.24 cfs @ 11.95 hrs, Volume= 2.156 af
Outflow = 28.83 cfs @ 12.02 hrs, Volume= 2.156 af, Atten= 27%, Lag= 3.8 min
Primary = 24.07 cfs @ 12.02 hrs, Volume= 2.125 af
Secondary = 4.81 cfs @ 12.01 hrs, Volume= 0.031 af
Routing by Dyn-Stor-Ind method, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs
Peak Elev= 850.12' @ 12.02 hrs Surf.Area= 8,649 sf Storage= 28,826 cf
Plug-Flow detention time= 251.7 min calculated for 2.155 af (100% of inflow)
Center-of-Mass det. time= 252.9 min ( 1,048.9 - 796.0 )
Volume Invert Avail.Storage Storage Description
#1 845.00' 36,958 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
845.00 1,060 0 0
846.00 4,240 2,650 2,650
847.00 5,163 4,702 7,352
848.00 6,263 5,713 13,065
849.00 7,370 6,817 19,881
850.00 8,496 7,933 27,814
851.00 9,792 9,144 36,958
Device Routing Invert Outlet Devices
#1 Primary 842.10'24.0" Round Culvert
L= 84.0' CMP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 842.10' / 829.44' S= 0.1507 '/' Cc= 0.900
n= 0.022, Flow Area= 3.14 sf
#2 Device 1 845.00'1.5" Horiz. 1yr - Orifice C= 0.600 Limited to weir flow at low heads
#3 Device 1 847.60'10.0" W x 24.0" H Vert. 10yr - Orifice C= 0.600
#4 Device 1 849.60'36.0" W x 6.0" H Vert. 50yr - Orifice X 4.00 C= 0.600
#5 Secondary 850.00'60.0' long x 8.0' breadth Broad-Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00
2.50 3.00 3.50 4.00 4.50 5.00 5.50
Coef. (English) 2.43 2.54 2.70 2.69 2.68 2.68 2.66 2.64 2.64
2.64 2.65 2.65 2.66 2.66 2.68 2.70 2.74
Primary OutFlow Max=22.93 cfs @ 12.02 hrs HW=850.09' TW=844.00' (Dynamic Tailwater)
1=Culvert (Passes 22.93 cfs of 29.33 cfs potential flow)
2=1yr - Orifice (Orifice Controls 0.13 cfs @ 10.86 fps)
3=10yr - Orifice (Orifice Controls 9.59 cfs @ 5.76 fps)
4=50yr - Orifice (Orifice Controls 13.20 cfs @ 2.25 fps)
Secondary OutFlow Max=4.24 cfs @ 12.01 hrs HW=850.09' (Free Discharge)
5=Broad-Crested Rectangular Weir (Weir Controls 4.24 cfs @ 0.75 fps)
Type II 24-hr 50yr-24hr Rainfall=7.10"Preliminary Model
Printed 10/27/2017Prepared by Burton Engineering Associates, Inc
Page 65HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Pond 4P: Detention
Inflow
Outflow
Primary
Secondary
Hydrograph
Time (hours)
12011511010510095908580757065605550454035302520151050Flow (cfs)42
40
38
36
34
32
30
28
26
24
22
20
18
16
14
12
10
8
6
4
2
0
Peak Elev=850.12'
Storage=28,826 cf
39.24 cfs
28.83 cfs
24.07 cfs
4.81 cfs
Type II 24-hr 50yr-24hr Rainfall=7.10"Preliminary Model
Printed 10/27/2017Prepared by Burton Engineering Associates, Inc
Page 66HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Stage-Area-Storage for Pond 4P: Detention
Elevation
(feet)
Surface
(sq-ft)
Storage
(cubic-feet)
845.00 1,060 0
845.10 1,378 122
845.20 1,696 276
845.30 2,014 461
845.40 2,332 678
845.50 2,650 928
845.60 2,968 1,208
845.70 3,286 1,521
845.80 3,604 1,866
845.90 3,922 2,242
846.00 4,240 2,650
846.10 4,332 3,079
846.20 4,425 3,516
846.30 4,517 3,964
846.40 4,609 4,420
846.50 4,702 4,885
846.60 4,794 5,360
846.70 4,886 5,844
846.80 4,978 6,337
846.90 5,071 6,840
847.00 5,163 7,352
847.10 5,273 7,873
847.20 5,383 8,406
847.30 5,493 8,950
847.40 5,603 9,505
847.50 5,713 10,071
847.60 5,823 10,647
847.70 5,933 11,235
847.80 6,043 11,834
847.90 6,153 12,444
848.00 6,263 13,065
848.10 6,374 13,696
848.20 6,484 14,339
848.30 6,595 14,993
848.40 6,706 15,658
848.50 6,817 16,334
848.60 6,927 17,022
848.70 7,038 17,720
848.80 7,149 18,429
848.90 7,259 19,150
849.00 7,370 19,881
849.10 7,483 20,624
849.20 7,595 21,378
849.30 7,708 22,143
849.40 7,820 22,919
849.50 7,933 23,707
849.60 8,046 24,506
849.70 8,158 25,316
849.80 8,271 26,137
849.90 8,383 26,970
850.00 8,496 27,814
850.10 8,626 28,670
850.20 8,755 29,539
Elevation
(feet)
Surface
(sq-ft)
Storage
(cubic-feet)
850.30 8,885 30,421
850.40 9,014 31,316
850.50 9,144 32,224
850.60 9,274 33,145
850.70 9,403 34,079
850.80 9,533 35,026
850.90 9,662 35,985
851.00 9,792 36,958
Type II 24-hr 50yr-24hr Rainfall=7.10"Preliminary Model
Printed 10/27/2017Prepared by Burton Engineering Associates, Inc
Page 67HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Summary for Pond 5P: Sand Filter
Inflow Area = 5.770 ac, 84.92% Impervious, Inflow Depth = 1.67" for 50yr-24hr event
Inflow = 1.23 cfs @ 12.06 hrs, Volume= 0.803 af
Outflow = 0.27 cfs @ 14.02 hrs, Volume= 0.803 af, Atten= 78%, Lag= 117.3 min
Primary = 0.27 cfs @ 14.02 hrs, Volume= 0.803 af
Secondary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af
Routing by Dyn-Stor-Ind method, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs
Peak Elev= 848.44' @ 14.02 hrs Surf.Area= 4,798 sf Storage= 14,010 cf
Plug-Flow detention time= 652.4 min calculated for 0.803 af (100% of inflow)
Center-of-Mass det. time= 652.0 min ( 1,673.9 - 1,021.9 )
Volume Invert Avail.Storage Storage Description
#1 844.00' 29,322 cf Custom Stage Data (Prismatic) Listed below
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
844.00 1,705 0 0
845.00 2,268 1,987 1,987
846.00 2,911 2,590 4,576
847.00 3,627 3,269 7,845
848.00 4,417 4,022 11,867
849.00 5,279 4,848 16,715
850.00 6,213 5,746 22,461
851.00 7,509 6,861 29,322
Device Routing Invert Outlet Devices
#1 Primary 843.50'6.0" Round Culvert
L= 40.0' RCP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 843.50' / 842.90' S= 0.0150 '/' Cc= 0.900
n= 0.010 PVC, smooth interior, Flow Area= 0.20 sf
#2 Device 1 844.00'Special & User-Defined
Head (feet) 0.00 1.50 3.00 4.50 6.00
Disch. (cfs) 0.000 0.138 0.207 0.276 0.345
#3 Secondary 849.50'60.0' long x 6.0' breadth Broad-Crested Rectangular Weir X 0.00
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00
2.50 3.00 3.50 4.00 4.50 5.00 5.50
Coef. (English) 2.37 2.51 2.70 2.68 2.68 2.67 2.65 2.65 2.65
2.65 2.66 2.66 2.67 2.69 2.72 2.76 2.83
Primary OutFlow Max=0.27 cfs @ 14.02 hrs HW=848.44' TW=843.34' (Dynamic Tailwater)
1=Culvert (Passes 0.27 cfs of 1.93 cfs potential flow)
2=Special & User-Defined (Custom Controls 0.27 cfs)
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=844.00' TW=845.00' (Dynamic Tailwater)
3=Broad-Crested Rectangular Weir ( Controls 0.00 cfs)
Type II 24-hr 50yr-24hr Rainfall=7.10"Preliminary Model
Printed 10/27/2017Prepared by Burton Engineering Associates, Inc
Page 68HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Pond 5P: Sand Filter
Inflow
Outflow
Primary
Secondary
Hydrograph
Time (hours)
12011511010510095908580757065605550454035302520151050Flow (cfs)1
0
Inflow Area=5.770 ac
Peak Elev=848.44'
Storage=14,010 cf
1.23 cfs
0.27 cfs0.27 cfs
0.00 cfs
Type II 24-hr 50yr-24hr Rainfall=7.10"Preliminary Model
Printed 10/27/2017Prepared by Burton Engineering Associates, Inc
Page 69HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Stage-Area-Storage for Pond 5P: Sand Filter
Elevation
(feet)
Surface
(sq-ft)
Storage
(cubic-feet)
844.00 1,705 0
844.10 1,761 199
844.20 1,818 397
844.30 1,874 596
844.40 1,930 795
844.50 1,987 993
844.60 2,043 1,192
844.70 2,099 1,391
844.80 2,155 1,589
844.90 2,212 1,788
845.00 2,268 1,987
845.10 2,332 2,245
845.20 2,397 2,504
845.30 2,461 2,763
845.40 2,525 3,022
845.50 2,590 3,281
845.60 2,654 3,540
845.70 2,718 3,799
845.80 2,782 4,058
845.90 2,847 4,317
846.00 2,911 4,576
846.10 2,983 4,903
846.20 3,054 5,230
846.30 3,126 5,557
846.40 3,197 5,884
846.50 3,269 6,211
846.60 3,341 6,537
846.70 3,412 6,864
846.80 3,484 7,191
846.90 3,555 7,518
847.00 3,627 7,845
847.10 3,706 8,247
847.20 3,785 8,649
847.30 3,864 9,052
847.40 3,943 9,454
847.50 4,022 9,856
847.60 4,101 10,258
847.70 4,180 10,660
847.80 4,259 11,063
847.90 4,338 11,465
848.00 4,417 11,867
848.10 4,503 12,352
848.20 4,589 12,837
848.30 4,676 13,321
848.40 4,762 13,806
848.50 4,848 14,291
848.60 4,934 14,776
848.70 5,020 15,261
848.80 5,107 15,745
848.90 5,193 16,230
849.00 5,279 16,715
849.10 5,372 17,290
849.20 5,466 17,864
Elevation
(feet)
Surface
(sq-ft)
Storage
(cubic-feet)
849.30 5,559 18,439
849.40 5,653 19,013
849.50 5,746 19,588
849.60 5,839 20,163
849.70 5,933 20,737
849.80 6,026 21,312
849.90 6,120 21,886
850.00 6,213 22,461
850.10 6,343 23,147
850.20 6,472 23,833
850.30 6,602 24,519
850.40 6,731 25,205
850.50 6,861 25,892
850.60 6,991 26,578
850.70 7,120 27,264
850.80 7,250 27,950
850.90 7,379 28,636
851.00 7,509 29,322
Type II 24-hr 50yr-24hr Rainfall=7.10"Preliminary Model
Printed 10/27/2017Prepared by Burton Engineering Associates, Inc
Page 70HydroCAD® 10.00-18 s/n 03513 © 2016 HydroCAD Software Solutions LLC
Summary for Pond 7P: Analysis Point
[40] Hint: Not Described (Outflow=Inflow)
Inflow Area = 13.900 ac, 35.25% Impervious, Inflow Depth = 3.43" for 50yr-24hr event
Inflow = 43.43 cfs @ 12.00 hrs, Volume= 3.974 af
Primary = 43.43 cfs @ 12.00 hrs, Volume= 3.974 af, Atten= 0%, Lag= 0.0 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs
Pond 7P: Analysis Point
Inflow
Primary
Hydrograph
Time (hours)
12011511010510095908580757065605550454035302520151050Flow (cfs)48
46
44
42
40
38
36
34
32
30
28
26
24
22
20
18
16
14
12
10
8
6
4
2
0
Inflow Area=13.900 ac
43.43 cfs43.43 cfs

STORM DRAINAGE HYDRAULIC MODEL 
10‐year, 24‐hour Storm Event 
Hydraflow Storm Sewer 

THIS DRAWING IS THE
PROPERTY OF BURTON
ENGINEERING ASSOCIATES
AND IS NOT TO BE
REPRODUCED OR COPIED IN
WHOLE OR IN PART. IT IS NOT
TO BE USED ON ANY OTHER
PROJECT AND IS TO BE
RETURNED UPON REQUEST.
5950 Fairview Rd. Suite 100 Charlotte, NC 28210
[phone] FIRM # C-1157
BURTON
ENGINEERING
LAND SURVEYORS
CIVIL ENGINEERS
ASSOCIATES STORM DRAINAGE CHARTProject:The Walking Co. ExpansionDate:01/13/2017Location:519 Lincoln County PkwyRevised:10/26/2017* Storm Frequency (on-site): 10-yr - C = 0.95Project No.:017.667.001* Pipe to be Class III unless otherwise notedComputed By:MBDGChecked By:CTBLineArea (ac)Area x CCInletTcSys.TciQ (cfs)Pipe:(%)(ft)(in)Invert(fps)Inlet/RimStd. No.RemarksFromToInletIncr.TotalCIAAccum.FullNSlopeLengthSizeUSDSVel.CO-13MH-120.950.860.860.905.005.007.156.116.118.000.0120.50%238.018851.73850.545.01855.857003-110-027Smooth Wall HDPEMH-12MH-110.865.005.007.156.116.118.000.0120.50%218.018850.54849.455.01856.45403Smooth Wall HDPEMH-11FES-100.865.005.007.156.116.118.000.0120.50%84.018849.92849.035.01858.68403Smooth Wall HDPEEX-CBCB-31.100.990.990.905.005.007.157.087.0817.300.0120.50%193.024848.11847.145.26852.34Smooth Wall HDPECB-3CB-21.501.352.340.905.005.007.159.6516.7317.300.0120.50%194.024847.14846.176.28852.00Smooth Wall HDPECB-2FES-10.340.312.650.905.005.007.152.2218.9531.400.0120.50%37.030846.17845.996.72852.47Smooth Wall HDPEOS-CMH-BREFER TO HYDROCAD MODEL IN CALCULATION PACKET24.7063.400.0126.6949.024839.75836.4818.95850.0050-YR STORM, CLASS III RCPMH-BFES-A24.7028.100.0120.4041.030824.76824.326.46843.2050-YR STORM, CLASS III RCP

EROSION CONTROL CALCULATIONS 
Sediment Skimmer Basin Spreadsheet 
Skimmer Sizing Spreadsheet 
Riprap Apron Sizing Spreadsheet 

Outfall ID:
Date:
Prepared By:
Checked By:
Outlet pipe diameter, Do (in)30
Tailwater depth (ft) 0.2
Tailwater Method To Be Used
Discharge (cfs) 24.7
Velocity (ft/s) 6.5
Minimum apron length, La (ft)*13
Apron width at pipe outlet (ft) 8
Apron width at outlet end (ft) 16
Riprap Class B
Riprap d50, (ft)0.5 (6in)
Max Stone Diameter, dmax (Inches) 9
Apron Thickness (Inches)** 14
W1 = 15.5'
Notes
W2 = 7.5'
The Walking Co. Burton Engineering Associates, Inc. 017.667.001
Riprap Apron Design
FES-A
MBDG
GTW
* Minimum Apron Length Is 10 Feet
** Minimum Apron Thickness Is 10 Inches
La = 13'
2017.04.02
Discharge Data
Apron Dimensions
Stone Specifications
Min TW (Fig. 8.06a)
Design procedure per NCDENR Riprap Outlet Protection Spreadsheet
Figure 8.06a: Design of outlet protection from a round pipe flowing full, minimum
Phase I Riser Basin Skimmer 10/27/2017
Phase I Riser Basin Skimmer NCDENR 6.61 & CLDS# 30.03A
Primary Spillway: Riser/ Barrel
Dewatering Mechanisim: Skimmer
Denuded Area 9.2 AC
Drainage Area 4.4 AC
Time of Concentration 5.0 Min.
Hydrology Method:
Rational
CIDA
Q2 = 0.6 x 5.48 x 4.4 = 14.5 CFS
Q10 = 0.6 x 7.15 x 4.4 = 18.9 CFS
Q50 = 0.6 x 8.62 x 4.4 = 22.8 CFS
Storage Requirements
Volume of Storage Req'd
1,800 CF/AC = 7,920 CF
Depth = 5.00 FT
Surface Area Req'd
8,211 SF offset
3
Size Basin
L = 2 x Width
L = 2W W=(SA/(2xH)^0.5 W = 65 L= 130 (Approximate for sizing purposes)
Area (SF) Elev
Top of Dam 11,313 850
Top Of Storage 9,669 848
7,904 847
Bottom of Storage 6,662 846
Bottom of Perm Pool 5,661 845
Volume of Storage Provided 16,070 CF
Surface Area Provided 9,669 SF
435 SF X Q10 =
100 AC Max Drainage Area
1,800 CF of Storage per Disturbed Area
435 SF of Surface Area per CFS of Q10 Peak 
Flow
2:1 Min. Length to Width Ratio
M+in. Depth 2.0 FT
Minimum 1 FT Freeboard
Minimum Dewatering Time = 24 hours
Min. of Three Baffles Required
Max of 15 FT Dam Height
Page 1 of 4P:\DWG\017.667.001 519 Lincoln County Parkway\6. Calcs\Erosion\ErosionControlCalcs-BEA-Ver2.2-01-26-16.xlsm
Phase I Riser Basin Skimmer 10/27/2017
Riser/Barrel Design
NCDENR:
Primary Design Storm:
10 Year 18.9 cfs
TRIAL BARREL DIAMETER 18 Hmax = 5.75 ft (above centroid of barrel)
Cd = 0.6
Qbarrel = 19.0 cfs 0.30 Invert of Riser/Barrel (Below bottom of storage, normaly 0))
RISER DIAMETER= 24 Inches h= 1.50 ft (Head Above Riser) (Min. of 1')

Qriser = 35.8 cfs (Orifice Eqn)
Qcontrol = 19.0 cfs (Lesser of Qbarrel & Qriser)
Riser/Barrel Passes Design Storm Yes
30 36
36 48
42 54
48 60
15 24
18 24
24 30
12 18
The primary spillway system must carry the peak runoff from
the 2-year storm, with the water surface at the emergency
spillway crest elevation
Inlet Proportions
Pipe Barrel
(in) Pipe Riser (in)RiserBarrel
Top of Dam
Spillway CrestYear Peak
Storage
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
Elev (ft)Dam X-Section
Page 2 of 4P:\DWG\017.667.001 519 Lincoln County Parkway\6. Calcs\Erosion\ErosionControlCalcs-BEA-Ver2.2-01-26-16.xlsm
Phase I Riser Basin Skimmer 10/27/2017
Size Skimmer
Table 6.64a
Head on Orifice of Various Skimmer Sizes
1.5
2
2.5
3
4
5
6
8
NCDENR 6.64
ed Dewatering Time = 3.0 Days (1 to 3 Days, NCDENR 6.61)
(Select Volume to Dewater)
Volume to Dewater = 7,920 CF Required
Qd = V / td= 2,640 CF/Day
umber of Skimmers = 1 Faircloth Skimmer http://www.fairclothskimmer.com/
Skimmer Dia. = 2.0 In. (Table 6.64a Above) Required Volume = 7,920 CF Provided Volume = 16,070 CF
H = 0.167 FT. Min. Time = 2 Days Max. Time = 5 Days
Orifice D = 1.67 IN. Skimmer Dia. =2.5 In. Skimmer Dia. =2.0 IN.
Use Orifice D = 1.75 IN.(Rounded to Nearest 0.25") Orifice D = 1.99 IN. Orifice D = 1.91 IN.
ual Dewatering Time = 2.7 Days Use Orifice D = 2.0 IN. Use Orifice D = 2.0
Skimmer
Size (In.) Head on Orifice (FT.)
0.125
0.208
0.250
0.333
0.333
0.417
0.500
0.167
Required
Page 3 of 4P:\DWG\017.667.001 519 Lincoln County Parkway\6. Calcs\Erosion\ErosionControlCalcs-BEA-Ver2.2-01-26-16.xlsm
Phase I Riser Basin Skimmer 10/27/2017
Emergency Spillway Design
NCDENR:
Q = Cw x L x H ^1.5, Cw=2.9
QEmerg.=Q10-Qprim.
Q10 = 18.9 CFS
QPrima.= 19.0 CFS
QEmerg. = -0.1 CFS
Weir Depth = 0.5 ft ( 6" Max )
Weir Length = -0.1 ft
Use Weir Length = 10.0 ft
Bouyancy Calculations
BF= VolRiser x DensityH2O
980 LBS
Wt. Conc.=145-62.4(LB/CF)=82.6 LB/CF
NCDENR:
SF= 1.2
WT OF ANCH. REQ'D= 1,176 LBS
VOL OF ANCH REQ'D= 14.2 CF Baffle Sizing
ANCHOR DIM'S
L= 7 ft
W= 7 ft 1st Inlet Zone 35% =

Treqd= 0.3 ft 2nd Inlet Zone 25% =
3.5 In.
3rd Inlet Zone 25% =
Tprov'd= 24 In.
Wt. Anchor Prov'd = 8,095 lbs Outlet Zone 15% =
SF provided = 8.26
Basin Data
Weir Width = 6.0 ft 6' Min Table 6.61 A (NCDENR)
Weir Length = 10.0 ft Acceptable Dim. For Basin Embankment
Weir Depth = 0.5 ft Min.
Weir FreeBoard = 1.0 ft
Top Dam Width 8.0 ft
Bottom Dam Width = 32 ft
Max. Sediment Depth = 2.50 ft
Total Height of Dam = 8.00 ft (Riser Height + 2 Year Peak + Weir FB + Weir Depth )
Basin Summary
Basin Surface Area
Required
(CF.)
Provided
(CF.)
Req'd
(SF.) Prov'd (SF.)
4.4 9.2 18.9 7,920 16,070 8,211 9,669 2.5 5.0 8.00 1.5 8.0 2.0 1.75 24 18
Barrel Dia
(In)Z (FT.)
T
(FT.)
W
(FT.)
Skim.
Size (In)
Skim.
Orifice
(Ft)
Riser
Dia (In)
Drainag
e Area
(AC)
Denuded
Area (AC)Q10 =
Basin Volume Cleanout
Depth
(FT.) H/2 H (FT.)
9,669
Fill Height Min. Top Width
Less than 10 Ft. 8.0 Ft.
10 F.t to 15 Ft. 10.0 Ft.
1,450 9,669
2,417 5,801
2,417 8,219
3,384 3,384
The spillway system must carry the peak runoff from the 10- year storm with a minimum 1
foot freeboard in the emergency spillway.
Protection against flotation- Secure the riser by an anchor with
buoyant weight greater than 1.1 times the water displaced by
the riser.
Req'd Area
(Sf) Cum. Area (Sf)
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