SW3221001_Design Calculations_20221006

WATER QUALITY CALCULATIONS
FOR
BRIGHTON PARK
MOUNT PLEASANT, CABARRUS COUNTY, NC
PREPARED BY:
LATHAM-WALTERS ENGINEERING, INC.
16507-A NORTHCROSS DRIVE
HUNTERSVILLE, N.C. 28078
Phone: [phone] Fax: [phone]
N.C. Corporate License C-1815
FOR
NIBLOCK HOMES, LLC
759 CONCORD PARKWAY NORTH SUITE 20
CONCORD, NC 28027
DATE: FEBRUARY 14, 2022
�o��NEsARO��
S L
°o S 3S6 _
"9,Q`°FNGINEE JP�O ,
REVISED: 6/4/2022
REVISED: 8/5/2022

Carlos L. Ruano P.E.
Latham -Walters Engineering, Inc.
16507-A Northcross Drive
Huntersville, NC 28078
Brighton Park BMP Design Summary
Brighton Park, located in Mt. Pleasant off Hwy-73, is a residential consisting of 178 single-family
lots. Sand Filters were computed & design according to the latest edition of NCDEQ Stormwater BMP
Manual, Mt. Pleasant Development Ordinance. Rainfall data came from the City of Concord Technical
Standards Manual as it was the nearest city close to Mt. Pleasant with recorded values. Post stormwater
run-off will be less or equal to pre -development values. BMPs were designed to the first one inch, 1 &
10-year storms; and spillways were designed for the 50-year storm. The first % inch of runoff and release
the stored volume in not less than 18 hours and not more than 36 hours.
Soil identity & aerial maps were inserted from Cabarrus County GIS. Curve Numbers (CN) will be
weighted per Mt. Pleasant Zoning & Hydrologic soil groups were computed from the Soil Survey of
Cabarrus County, NC. 5 min time of concentration was used for post -development.
Figure 1: Open Bottom Sand Filter Example: Cross -Section
OPTIONAL FLOW DIVERSION r TEMPORARY WATER SURFACE GRAVE LISTONESURFACE
STRUCTURE
CLEANOUT SAND FILTER MEDIA PROPOSED GRADE
SEDIMENT {PROVIDE AT (ASTM C-33 SAND OR
INFLOW CH(FOBAY] LEAST ONE! EQUIVALENT] I' OVERFLOW
-} O �� —
3.1 ...;.
SLOPE .. ...
J[
T
PERFORATED STANDPIPF 3'1
DETENTION STRUCTURE SLOPE
1
IN -SITU SOIL OUTFLOW
PERFORATED PIPE 1 SOLID PIPE
a�
SEASONALHIGH -
WATER TABLE}
NOTES: —
THE MINIMUM COMBINED VOLUME OF SEDIMENT CHAMBER AND STORAGE ABOVE SAND
FILTER MEDIA IS D75 TIMES THE TREATMENT VOLUME.
MAINTAIN SAND FILTER MEDIA SUCH THAT THE INFILTRATION RATE IS GREATER THAN OR
EQUAL TO 2 INCHES PER HOUR (2"MR)
C-6. Sand Filter 2 Revised: 1112012020

MOUNT PLEASANT DEVELOPMENT ORDINANCE Article 10
involved, and approved by town Public Works Director or their designee will be considered. Any concrete pipe
laid between the concrete curbs shall be reinforced. All pipe shall be laid with the bell or groove upgrade and
joint entirely interlocking.
M. Catch basins shall be built as shown on the standard drawings. Improvised grates will not be acceptable. Catch
basins walls shall be built straight with inside joints struck smooth. Precast catch basins may be acceptable with
the approval of the town Public Works Director or their designee.
10.3.5. DETENTION FACILITY DESIGN STANDARDS
A. The detention facility must limit the 1-year and 10-year developed discharge rates to pre -developed peak
discharge rates. Emergency spillways shall be designed to accommodate 50-year frequency storms or as may be
required by the North Carolina Dam Safety Law. In areas specifically designated as sensitive water quality areas,
[for example, within watershed protection overlay districts and the River/Stream Overlay District (RSOD) or
other applicable Overlay Districts the more stringent design criteria applies.
B. Design and installation of all storm water detention or other impoundment facilities shall comply with applicable
federal, state and local laws.
C. In no case, shall a habitable structure be located within the impoundment area of any storm water detention facility
or over a storm water drainage line.
D. No utilities (sanitary sewer lines, underground power lines, water lines, etc.) shall be located within any
impoundment facility.
E. No structures may be located over storm drain lines not associated with the detention system.
F. Impoundment facilities located within automobile parking areas shall not exceed a maximum water depth of ten
(10) inches.
G. All impoundment facilities will be considered permanent.
H. Maintenance of all impoundment or detention facilities will be the responsibility of the property owner. Adequate
provisions for such private maintenance shall be included in a declaration of covenants for subdivisions which
shall be approved by the Town Board and recorded by the Cabarrus County Register of Deeds. Stormwater
management plans shall be developed for site developments not associated with a subdivision development and
shall be approved by the Public Works Director and recorded by the Cabarrus County Register of Deeds. Failure
to maintain a storm water detention or impoundment facility shall be considered a violation of this ordinance and
shall be subject to penalties as set forth in Article 1.6 of this Ordinance.
I. Impoundment or detention facilities which may impact existing storm drainage systems may be required to be
protected by a "drainage detention easement" recorded by the Cabarrus County Register of Deeds.
J. Impoundment facilities which may impact existing storm drainage systems may be required to be protected by a
"drainage detention easement" recorded by the Cabarrus County Register of Deeds.
K. Detention facilities within areas specifically designated as sensitive water quality areas, (for example, within
protected water supply watersheds or stream riparian buffers) shall comply with the regulations and design criteria
for those areas.
L. Vegetated and rip -rap protected embankments shall have side slopes no steeper than 3:1 (h:v) within open spaces
10-22

MOUNT PLEASANT DEVELOPMENT ORDINANCE Article 10
and no steeper than 2:2 (h:v) elsewhere, and shall meet requirements of the Dam Safety Act when necessary.
M. Tmpoundment facilities located within automobile parking areas shall not exceed a maximum water depth of six
(6) inches in code -required parking areas, 10 inches in additional parking area, and 15 inches in truck storage and
loading areas.
N. The stormwater detention facilities in High Quality Water (HQW) or source water protection areas shall detain
the first'/, inch of runoff and release the stored volume in not less than 18 hours and not more than 36 hours.
O. The following hydrologic soil groups shall apply for Cabarrus County, North Carolina:
Series Name
Hydrolojic Group
Altavista
C
Appling
B
Armenia
D
Badin
C
Cecil
B
Chewacla
C
Coronaca
B
Cullen
C
Enon
C
Georgeville
B
Goldston
C
Herndon
B
Hewassee
B
Iredell
C/D
Kirkscy
C
Mecklenburg
C
Misenheimer
C
Pacolet
B
Poindexter-
B
Sedgefield
C
Tatum
C
Vance C
Wehadkee D
Source: United States Department of Agriculture, Soil Conservation Service, Soil Survey of Caharrus
Countv, North Carolina, Table 16. Page 86 and pages 124-126 of the Soil Survey of Cabarrus County,
North Carolina shows permeability ratings by depth and type for each soil type.
P. Stormwater- detention or impoundment facilities shall be located on the site from which the run-off to be
controlled is generated; provided, however, that off -site impoundment facilities are acceptable provided the
land area involved within the facility is delineated on an acceptable map and officially recorded by the
Cabarrus County Register of Deeds as a permanent "drainage detention easement." Regional detention
facilities are allowed if approved by the Public Works Director or their designee and if the development plans
provide for the proper operation, inspection, and maintenance of the facilities in perpetuity through a
restrictive covenant or other legal, enforceable mechanism.
Q. Stormwater facilities to be located in designated open space areas shall be regulated in accordance with
Article 6 of this Ordinance.
10-23

Cabarrus County, North Carolina
TABLE 16.--SOIL AND WATER FEATURES
127
["Flooding" and "water table" and terms such as "rare," "brief," "apparent," and "perched" are explained in the
text. The symbol < means less than; > means more than. Absence of an entry indicates that the feature is
not a concern or that data were not estimated]
riuouing ; Hign water table ; Bedrock I Risk of corrosion
Map symbol and 'Hydro -I I I I I I I I I I
soil name I logicl Frequency I Duration 'Months I Depth I Kind IMonths IDepthlHard- IUncoated (Concrete
!�1 I I I , , , ness , steel
AaB--------------- 1 C Rare --------
Altavista '
ApB---------------I
Appling '
Ar----------------I
Armenia '
BaB, BaD, BaF-----'
Badin
CcB2, CcD2--------
Cecil
CeB:
Cecil ------------
Urban land.
Cb----------------
Chewacla
B +None--------
'
D 'Rare--------
I
C INone--------
B !None --------
B
C
CoB, CoD----------` B
Coronaca '
CuB2, CuD2--------' C
Cullen
EnB, EnD----------I C
Enon {
EoB: I
Enon-------------I C
Urban land. I
GeB2--------------' B
Georgeville {
GoC, GoF----------' C
Goldston '
HeB---------------I B
Herndon '
HwB, HwD----------I B
Hiwassee 1
IdA, IdB----------I C/D
Iredell
CkB---------------I C
Kirksey ,
I — 1 I
'1.5-2.5IApparentlDec-Mar
I I I
' >6.0 ' --- ' ---
I0.5-1.5IApparent
I I
' >6.0 ' ---
I I
' >6.0 I ---
I I I I I
(None --------I --- I --- ' >6.0 ' ---
{ I I I I
IFrequent----IBrief-----INov-Apr'0.5-1.5'Apparent
I I I I I
'None --------I --- I --- ' >6.0 ' ---
I I I I
(None --------I --- I --- ' >6.0 I ---
I
(None -------- I --- ' --- I >6.0 I ---
I I I I I I
(None--------I --- I --- I >6.0
I I I I I I
±None--------j --- ± ---
{ { I
(None --------I --- I ---
I I I
!None -------- I --- ---
(None --------I --- I ---
I I I
(None --------I --- I ---
I I I
(None --------I --- I ---
I I I
i i i
' >6.0 I ---
I I
I1.0-2.OIPerched
I I
I1.5-3.OIPerched
I I
'Dec-Aprl >60 ' ---
I I I
1 --- 120-401Goft
I '40-60IHard
' --- ' >60' ---
I I
--- ' >60 ' ---
I I
Nov-Aprl >60 ' ---
--- I >60 I ---
I I
--- I >60 ' ---
I I
--- ' >60' ---
I I
--- ' >60 ' ---
I I
--- i >60 i ---
--- 110-201Soft
120-40'Hard
--- ' >60 ' ---
>60
Dec -Apr' >40 +Soft
I I
Dec-Mar140-60ISoft
I I
'Moderate 'Moderate.
I I
'Moderate 'Moderate.
'High ----- ILow.
I I
(High ----- (High.
'Moderate (Moderate.
I I
'Moderate (Moderate.
'High I g I '
'High -----(Moderate.
(High -----(Moderate.
(High -----(Moderate.
I I
'High ----- (Moderate.
I I
(High ----- (High.
'Moderate 'High.
(High -----(High.
I I
'Moderate (Moderate.
I I
'High-----ILow.
'Moderate 'High.
I I

128
Soil Survey
TABLE 16.--SOIL AND WATER FEATURES --Continued
Flooding HT q water table , Bedrock , Risk oT corrosion
reap symDoi auu nyuLu-
soil name I louicl Frequency I Duration (Months
gr
I Depth I Kind IMonths IDepthlHard- (Uncoated (Concrete
Hess steel
I t I
I I In I {
I
I
MeB, MeD----------- I
I
I
C INone
I
{
-------- I
I
I
--- I
I
_-- I >6 0 I
I I
___ I ___ 148-60ISoft (High
I I I I
----- (Moderate.
I
Mecklenburg
I
I
I
I
I I
I I I I
I
MkB: I
Mecklenburg ------- I
I
C INone
I
-------- I
I
--- I
I I
I >6.0 I
I I
I I I I
I I48-60ISoft IHigh
I I I I
I
----- iModerate.
I
Urban land. I
I
MsA---------------- I
I
I
C INone
I
I
-------- I
I
I
--- I
I I
I1.0-1.5IPerched
I I I I
IDec-MayllO-20ISoft IHigh
20-40 Hard
I
------ IHigh.
Misenheimer
I
PaF---------------- I
I
B ±None
I
-------- I
I
--- I
I I
--- I >6.0 I
I I I I
--- I --- I >60 I --- +High
I
----- iHigh.
Pacolet I
I
I
I
I I
I I I I
I
PcE3: I
Pacolet ---------- I
I
I
B INone
I
-------- I
I I
I
--- l
I
I I
--- 1 >6.0 1
I {
I I I I
--- l --- 1 >60 1 ---
I I I I
I
IHigh -----
I
IHigh.
I
Udorthents. I
I
PoB, PoD, PoF-----1
I
B
I I
I I
(None -------- I
I I
---
I I I
I I I
I __- I >6.0
I I
I I I
I I I
I I ___ 120-401Soft
I I G-601Hard
I
I
iModerate
1
I
IModerate.
1
Poindexter
SfB---------------
{
I C
I
I
INone--------
I
I
I ---
I
I I
I --- 11 0-1 SlPerched
I I
I I I I
IJan-Marl >48 IHard
I I I I
I
IHigh -----
I
I
IModerate.
I
Sedgefield
I
I
I
I I
I I I I
I
I
I
TaB, TaD, TbB2,
TbD2--------------
I
I C
{
I
INone--------
I
I
I ---
I
{ I
l --- 1 >6 0
I I
I I I I
1 --- I --- 140-601Soft
I { I I
I
lHigh-----IHigh.
I
I
Tatum
I
I
I
I I
I I I I
I
I
I
Ud.
Udorthents
I
l
{
1
l
{
{
1
I
I I
I I
I {
I I I I
I I I I
I I I I
{
I
I
I
I
I
Ur.
Urban land
l
I
l
I
1
1
I
I I
I I
I I
I I I I
I I I I
I I I I
I
I
I
I
I
VaB, VaD----------
I
I C
1
I
INone--------
1
1 ---
I
l --- I >6.0
I I
1 --- 1 --- 1 >60 ISoft
I I I I
IHigh -----
I
IHigh.
I
Vance
We ----------------
{
I D
{
(Frequent ----
I
(Brief -----
I I
INov-Jung 0-2.5IApparentlDec-May`
I I I I
>60 1 ---
I
IHigh -----
I
iModerate.
Webadkee
I
1
I
I I
I I I I
I
I

SECTION 2
STORMWATER RUNOFF
TABLE 2-1
APPROXIMATE 24-HOUR RAINFALL
VOLUMES FOR CONCORD, NC
Return Interval
24-hour Volume inches
1- ear
2.9
2-year
3.5
5-year
4.4
10-year
5.1
25- ear
6.0
50-year
6.8
100- ear
7.6
2.2.2 Intensity -Duration -Frequency Curves
Intensity -duration -frequency (IDF) curves have been developed for the area and are shown in
Figure 2-2, on page 2-5. The curves for 1-, 2-, 5-, 10-, 25-, 50-, and 100-year storm events with
durations from 5 minutes to 24 hours. Ordinates from the Figure 2-2 have been provided in
Table 2-3, on page 2-5.
2.2.3 Design Storm Recurrence Intervals
The selection of the recurrence interval to be used for the design storm shall be in accordance with
Section 1.3, Design Policy.
Adopted January 10, 2008 2-2 Technical Standards Manual

SECTION 2
STORMWATER RUNOFF
TABLE 2-10
RUNOFF CURVE NUMBER FOR URBAN AREAS AND OTHER
AGRICULTURAL LANDS'
Average Percent
Curve Numbers for
'c
Cover Description
H drolo Soil Group
Cover Type and Hydrologic Condition
Impervious
A
B
C
I D
Area
Fully developed urban areas (vegetation established)
Open space (lawns, parks, golf courses, cemeteries, etc.)'
Poor Condition (grass cover <50 percent)
68
79
86
89
Fair Condition (grass cover 50 to 75 percent)
49
69
79
84
Good Condition (grass cover >75 percent)
39
61
74
80
Impervious areas:
Paved parking lots, roofs, driveways, etc., (excluding
right-of-ways)
98
98
98
98
Streets and roads:
Paved; curbs and storm sewers (excluding right-of-
ways)
98
98
98
98
Paved; open ditches (including right-of-ways)
83
89
92
93
Gravel (including right-of-ways)
76
85
89
91
Dirt (including right-of-ways)
72
82
87
89
Urban districts:
Commercial and business
85
89
92
94
95
Industrialf
72
81
88
91
93
Residential districts by average lot size:
RE - maximum of 1 dwelling per acre
20
51
68
79
84
RL - maximum of 2 dwellings per acre
25
54
70
80
85
RM-1 - maximum of 3 dwellings per acre
30
57
72
81
86
RM-2 - maximum of 4 dwellings per acre
38
61
75
83
87
RV - maximum of 8 dwelling/acre
65
77
85
90
92
RC - maximum of 15 dwelling/acre
80
86
90
93
96
Developing urban areas and agricultural land
Newly graded areas (pervious areas only, no vegetation)4
77
86
91
94
Pasture, grassland, or range — continuous forage for grazing
Poor
68
79
86
89
Fair
49
69
79
84
Good
39
61
74
80
Meadow -continuous grass, protected from grazing and
-
30
58
71
78
generally mowed for hay
Brush -brush, weed, grass mixture with brush the major
Poor
48
67
77
83
elements6
Fair
35
56
70
77
Good
730
48
65
73
Woods -grass combination (orchard or tree farm)'
Poor
57
73
82
86
Fair
43
65
76
82
Good
32
58
72
79
Woods9
Poor
45
66
77
83
Fair
36
60
73
79
Good
430
55
70
77
Farmsteads -buildings, lanes, driveways, and surrounding lots.
-
59
74
82
86
Source: SCS, Urban Hydrology for Small Watersheds, Technical
Release No. 55.
Adopted January 10, 2008 2-25 Technical Standards Manual

Soil Map
754 MeR f475fi%6~' ..�� s•i Fun,B?n0�,721558976 E= 7B 0,818225 CuB2 0,51'7E9
r En 1,72
CUB2 (1,-465121 OJ32 1.'96292 OJF,2 1,360433 EnB 0,74321;En
r
38.ChA 0,872137 EnB 0,58u4ii OjB2 0,32'3047 CUF2 1.385968nB 1,]2420 9'
, IeB 1.041233 Ch1, 0.485025 EnF. Z.
EnB 79 8
MR&�!EnFs 0,83315E 8" n=
431724 ChA 0.7456f 3 - [, + En
�P
EnB 0,0�'Su06 •x
EnB 11.736198
+ EnB C,051357.*
' CuB214.216587 °` ...
MeD 7.559036 ti- CuE,2 1.962733 MeD 1,61954E
4 * EnB
''- CuF,2 1.753f.33
EnB 11.736198
EnB 0,338706 CuB2 1,805954
MeD 2,60i
A 1,7. {188 OJB2 :KZ1658 .
`4's '-A MFD 0,1??J55
{
k� �t
Cu'32 0.32522
CcD2 4.248163 �
r
VaD 12,0418
#�� VaB 0,0991y^T
- VaFj 0.811241 CcD2 0,22:611
m ' Vaa 0,4260 2CcD2 0 449475..gW-.
+ ' Ccu ?,3680t.6 Ch x 0.508445
VaB 1.541643 VaE• 0.11 { 3ij
VaL� 0.33.585 CcD2 0,3SgOto . .
L. Ch 1 0.416361
r. * a3 0,250f'S1 VaB 0,5898�:3 VaB 0,rJ83E4-
rS�i439a�E ,,;a Cam'- 0,35-8C'9 FnD 0,'2
"�..
M1 x l,�B 0,94741 Var, 0,35136,.E +(,
Z ._. Cho 0.804502
A 0.647467.. - r .1 ,
VaB 39.073159. :cD� 0.26 2 Chfi 0,580.'83 F.7
Meld 5 b93 yy'# C 2 0,18C073
. 9 15.� aA 0.38766
.. r +VaD 0,459453F• _n1, 0,
cD2 0,130697 C7A 049037
E-7D C.,17a

SAND FILTER- I
r

Mt. Pleasant, NC
Sand Filter Calculation
1. Calculate Runoff Coeff, (Rv)
Drainage area to filter, Ad =
Impervious area to filter forebay=
Impervious percentage =
Rv = 0.05 + 0.9(la) _
2. Calculate req'd water quality volume (WQV)
Brighton Park
1
17.86 ac
8.96 ac.
50.16%
0.50146456
Storage:
Cum
Elev.
Area
Vol.
Vol
609
15725
0
0
610
17252
16488.5
16488.5
612
20478
37730
54218.5
614
23930
44408
98626.5
616
27606
51536
150162.5
Calculate Depth for WQ Volume:
609
0
610.97
32511
610
16488.5
WQV = (Rv/1 x Ad/1 x 43560 sf/1 ac x Rd/1 x ft/12 in)
WQV = 32511 cf (used to size Af)
WQV= 0.7463 ac-ft.
Elevation of WQ Volume = 610.97 774.11 from Routing
3. Convert Water Quality Volume, WQv to inches of runoff.
WQv = 1.0(Rv) = 0.50 inches
4. Site Hydrologic Input Parameters:
Cn Pre = 72.0
Cn Post = 80.0 to pond

Table 4.8.3 Results of Hvdrolooic Calculations from HvdroCad
Condition
Q 1- ear
Q 10- r.
Q 25- r
Q 50 yr
Runoff
Pre Dev.
12.37
47.73
55.29
67.84
Post. Dev.
39.11
97.31
122.16
144.39
Routed
0.94
7.94
23.71
24.83
Peak Stage
611.71
614.32
614.92
615.66
Disch. Time
1140 Hours
1
1
10.4' Freeboard
Required
5. First 1/2 inch 0.74 ac-ft 32415.9 cf
Detain 18 hrs 47105 cf Provided
36 hrs 29074 cf
Release Peak-36 hrs 47136 cf Provided
6. Channel Protection Volume: CPv to be held for 24 hours + 12 hours = 36 hours
S = 1000/Cn-10 where Cn = 80.0
S = 2.50 inches
Compute total runoff for the 1-year, 24-hour storm event. Total rainfall depth is
Qd = (P-0.2S)^2/(P+0.8S) 2.9 1-year storm
Qd= 1.18 inches
Watershed Runoff = (Qd)(DA)(1 ft/12") = 1.75 ac-ft. = 1.066 per Hydro -CAD
From HydroCad- Max Release Rate = 0.94 cfs
From HydroCad: Maximum Stage: 611.71
Storage: 45532 cf
Drawdown Time: 140 Hours
7. Sedimentation Basin Surface Area
Min As = 0.20 x WQV = As = 6502 sf
8. Sand Filter Bed Surface Area (Af)
2638 sf
Af = (WQV x df)/(k x t x (ha + df) ha = average head
df = 1.5 (depth of filter media)
hmax = 1.97
OK
Calculate Ha = hmax/2 = 0.99 ft
Where df = depth of filter bed (15), k = permeability of sand (3.5), ha = avg depth, t=51 hrs=2.125 days
Af = 2638 sf 385.10 cf/hr = 0.1069709 cfs
hmax = 1.971728781 32511 cf/(As + Af)
Choose As + Af = 9140 sf
Per plan, As = 4069
Af = 7555
Total 11624

9. Sand Filter Drawdown Calculation
Coeff. Of Permeability of filter media = 3.5ft/day = 0.146 ft/hr
Volume of water drained in one hour = 0.146 ft/hr x Af s.f. = 385.0951 cf/hour
Drawdown Time = WQV/Drawdown Rate = 84.42 hrs 3.517621 days
Underdrain Calculations:
78 I.f of underdrain shown; provide 6" perforated pvc pipe with 3/8" perforations spaces 3" o.c. - 4 longitudinal rows
spaced 90 degrees apart.
134 I.f. of pipe
134 I.f. x 4 rows/ft x 4 holes/ft = 2144 holes
50% of perforations = 1072 holes
Capacity of one hole = 0.0083 cfs based upon CA(2gh)^0.5
Total Capacity = 8.8976 cfs which is 83.2 times the capacity of the sand filter.
Total Capacityof 6" PVC @ 0.50% is 0.40 cfs (0.20 cfs assuming 50% clogged) from Mannings and BMP Manual.
10. Antiflotation Calculation
8 Height of Riser, ft.
6 Area of Riser, s.f.
48 Volume of Riser, c.f.
2995.2 Weight of Water @ 62.4 pcf
3294.72 Weight of water with safety factor of 1.1
82.6 Buoyant Wt. of Concrete = (145-62.4) pcf
1.48 Volume of Concrete Req'd in c.y.
39.89 Volume of Concrete Req'd in c.f.
48 Volume of Concrete in Structure (cf)
-8.11 Volume of Concrete Required (cf)
0.5 ft thick
2.8 Length/Width
(If negative, additional concrete weight not required)

Brighton Park
Mt. Pleasant, NC
1. Develop Stage -Discharge Data for Sand Filter Media.
From 4.8.18 of the BMP Standards Manual:
Q = Af(k)(h+df)/(df)
Latham -Walters Engineering, Inc.
16507-A Northcross Drive
Huntersville, NC 28078
where Af = surface area of filter bed = 2638 sf
df = filter bed depth, ft. = 1.5 ft.
k = coefficient of permeability of filter media (ft/day) _ ft/day
h = average height of water above filter bed (ft) 12, etc.
h
Q
cf/day
Q
cfs
1
15386.22
0.178
2
21540.71
0.249
3
27695.2
0.321
4
33849.69
0.392
5
40004.17
0.463
6
46158.66
0.534
7
52313.15
0.605
8
58467.64
0.677
9
64622.13
0.748
10
70776.62
0.819

(Predeveloped)
2S �
(Post Developed)
Subcat Reach on Link
3P
(BMP1)

2020.17-BMP1 REVISED
Prepared by {enter your company name here} Page 2
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/4/2022
Area Listing (all nodes)
Area (acres) CN Description (subcats)
3.600 60 Woods, Fair, HSG B (1S)
3.500 69 Pasture/grassland/range, Fair, HSG B (1S)
3.200 73 Woods, Fair, HSG C (1 S)
7.090 75 RM-2 (B) (2S)
7.560 79 Pasture/grassland/range, Fair, HSG C (1S)
10.770 83 RM-2 (C) (2S)
Miry►"k1]

2020.17-BMP1 REVISED Type 11 24-hr 1-yr Concord Rainfall=2.90"
Prepared by {enter your company name here} Page 3
HvdroCAD® 8.00 s/n 004317 © 2006 HvdroCAD Software Solutions LLC 6/4/2022
Time span=0.00-200.00 hrs, dt=0.01 hrs, 20001 points
Runoff by SCS TR-20 method, UH=SCS
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment 1S: (Predeveloped) Runoff Area=17.860 ac Runoff Depth=0.75"
Flow Length=1,107' Tc=22.5 min CN=72 Runoff=12.37 cfs 1.115 of
Subcatchment 2S: (Post Developed) Runoff Area=17.860 ac Runoff Depth=1.18"
Tc=5.0 min CN=80 Runoff=39.11 cfs 1.750 of
Pond 3P: (BMP1) Peak Elev=611.71' Storage=48,260 cf Inflow=39.11 cfs 1.750 of
Primary=0.94 cfs 1.749 of Secondary=0.00 cfs 0.000 of Outflow=0.94 cfs 1.749 of
Total Runoff Area = 35.720 ac Runoff Volume = 2.865 of Average Runoff Depth = 0.96"
100.00% Pervious Area = 35.720 ac 0.00% Impervious Area = 0.000 ac

2020.17-BMP1 REVISED
Type 11 24-hr 1-yr Concord Rainfall=2.90"
Prepared by {enter your company name here} Page 4
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/4/2022
Subcatchment 1S: (Predeveloped)
BASED ON EXISTING CONDITIONS
Runoff = 12.37 cfs @ 12.18 hrs, Volume= 1.115 af, Depth= 0.75"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Type II 24-hr 1-yr Concord Rainfall=2.90"
Area (ac)
CN
Description
3.200
73
Woods, Fair, HSG C
3.600
60
Woods, Fair, HSG B
3.500
69
Pasture/grassland/range, Fair, HSG B
7.560
79
Pasture/grassland/range, Fair, HSG C
17.860
72
Weighted Average
17.860
Pervious Area
Tc
Length
Slope
Velocity
Capacity Description
(min)
(feet)
(ft/ft)
(ft/sec)
(cfs)
10.7
100
0.0371
0.16
Sheet Flow,
Grass: Dense n= 0.240 P2= 3.50"
6.6
719
0.0672
1.81
Shallow Concentrated Flow,
Short Grass Pasture Kv= 7.0 fps
5.2
288
0.0347
0.93
Shallow Concentrated Flow,
Woodland Kv= 5.0 fps
22.5 1,107 Total

2020.17-BMP1 REVISED
Type // 24-hr 1-yr Concord Rainfall=2.90"
Prepared by {enter your company name here} Page 5
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/4/2022
Hydrograph for Subcatchment 1S: (Predeveloped)
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
0.00
0.00
0.00
0.00
2.00
0.06
0.00
0.00
4.00
0.14
0.00
0.00
6.00
0.23
0.00
0.00
8.00
0.35
0.00
0.00
10.00
0.52
0.00
0.00
12.00
1.92
0.26
5.45
14.00
2.38
0.47
1.13
16.00
2.55
0.56
0.70
18.00
2.67
0.62
0.54
20.00
2.76
0.67
0.40
22.00
2.83
0.71
0.36
24.00
2.90
0.75
0.34
26.00
2.90
0.75
0.00
28.00
2.90
0.75
0.00
30.00
2.90
0.75
0.00
32.00
2.90
0.75
0.00
34.00
2.90
0.75
0.00
36.00
2.90
0.75
0.00
38.00
2.90
0.75
0.00
40.00
2.90
0.75
0.00
42.00
2.90
0.75
0.00
44.00
2.90
0.75
0.00
46.00
2.90
0.75
0.00
48.00
2.90
0.75
0.00
50.00
2.90
0.75
0.00
52.00
2.90
0.75
0.00
54.00
2.90
0.75
0.00
56.00
2.90
0.75
0.00
58.00
2.90
0.75
0.00
60.00
2.90
0.75
0.00
62.00
2.90
0.75
0.00
64.00
2.90
0.75
0.00
66.00
2.90
0.75
0.00
68.00
2.90
0.75
0.00
70.00
2.90
0.75
0.00
72.00
2.90
0.75
0.00
74.00
2.90
0.75
0.00
76.00
2.90
0.75
0.00
78.00
2.90
0.75
0.00
80.00
2.90
0.75
0.00
82.00
2.90
0.75
0.00
84.00
2.90
0.75
0.00
86.00
2.90
0.75
0.00
88.00
2.90
0.75
0.00
90.00
2.90
0.75
0.00
92.00
2.90
0.75
0.00
94.00
2.90
0.75
0.00
96.00
2.90
0.75
0.00
98.00
2.90
0.75
0.00
100.00
2.90
0.75
0.00
102.00
2.90
0.75
0.00
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
104.00
2.90
0.75
0.00
106.00
2.90
0.75
0.00
108.00
2.90
0.75
0.00
110.00
2.90
0.75
0.00
112.00
2.90
0.75
0.00
114.00
2.90
0.75
0.00
116.00
2.90
0.75
0.00
118.00
2.90
0.75
0.00
120.00
2.90
0.75
0.00
122.00
2.90
0.75
0.00
124.00
2.90
0.75
0.00
126.00
2.90
0.75
0.00
128.00
2.90
0.75
0.00
130.00
2.90
0.75
0.00
132.00
2.90
0.75
0.00
134.00
2.90
0.75
0.00
136.00
2.90
0.75
0.00
138.00
2.90
0.75
0.00
140.00
2.90
0.75
0.00
142.00
2.90
0.75
0.00
144.00
2.90
0.75
0.00
146.00
2.90
0.75
0.00
148.00
2.90
0.75
0.00
150.00
2.90
0.75
0.00
152.00
2.90
0.75
0.00
154.00
2.90
0.75
0.00
156.00
2.90
0.75
0.00
158.00
2.90
0.75
0.00
160.00
2.90
0.75
0.00
162.00
2.90
0.75
0.00
164.00
2.90
0.75
0.00
166.00
2.90
0.75
0.00
168.00
2.90
0.75
0.00
170.00
2.90
0.75
0.00
172.00
2.90
0.75
0.00
174.00
2.90
0.75
0.00
176.00
2.90
0.75
0.00
178.00
2.90
0.75
0.00
180.00
2.90
0.75
0.00
182.00
2.90
0.75
0.00
184.00
2.90
0.75
0.00
186.00
2.90
0.75
0.00
188.00
2.90
0.75
0.00
190.00
2.90
0.75
0.00
192.00
2.90
0.75
0.00
194.00
2.90
0.75
0.00
196.00
2.90
0.75
0.00
198.00
2.90
0.75
0.00
200.00
2.90
0.75
0.00

2020.17-BMP1 REVISED Type 11 24-hr 1-yr Concord Rainfall=2.90"
Prepared by {enter your company name here} Page 6
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/4/2022
Subcatchment 2S: (Post Developed)
Runoff = 39.11 cfs @ 11.96 hrs, Volume= 1.750 af, Depth= 1.18"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Type II 24-hr 1-yr Concord Rainfall=2.90"
Area (ac) CN
Description
10.770 83
RM-2 (C)
7.090 75
RM-2 (B)
17.860 80
Weighted Average
17.860
Pervious Area
Tc Length
Slope Velocity Capacity Description
(min) (feet)
(ft/ft) (ft/sec) (cfs)
5.0
Direct Entry,

2020.17-BMP1 REVISED
Type // 24-hr 1-yr Concord Rainfall=2.90"
Prepared by {enter your company name here} Page 7
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/4/2022
Hydrograph for Subcatchment 2S: (Post Developed)
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
0.00
0.00
0.00
0.00
2.00
0.06
0.00
0.00
4.00
0.14
0.00
0.00
6.00
0.23
0.00
0.00
8.00
0.35
0.00
0.00
10.00
0.52
0.00
0.03
12.00
1.92
0.52
34.29
14.00
2.38
0.81
1.35
16.00
2.55
0.93
0.86
18.00
2.67
1.01
0.68
20.00
2.76
1.07
0.50
22.00
2.83
1.13
0.46
24.00
2.90
1.18
0.43
26.00
2.90
1.18
0.00
28.00
2.90
1.18
0.00
30.00
2.90
1.18
0.00
32.00
2.90
1.18
0.00
34.00
2.90
1.18
0.00
36.00
2.90
1.18
0.00
38.00
2.90
1.18
0.00
40.00
2.90
1.18
0.00
42.00
2.90
1.18
0.00
44.00
2.90
1.18
0.00
46.00
2.90
1.18
0.00
48.00
2.90
1.18
0.00
50.00
2.90
1.18
0.00
52.00
2.90
1.18
0.00
54.00
2.90
1.18
0.00
56.00
2.90
1.18
0.00
58.00
2.90
1.18
0.00
60.00
2.90
1.18
0.00
62.00
2.90
1.18
0.00
64.00
2.90
1.18
0.00
66.00
2.90
1.18
0.00
68.00
2.90
1.18
0.00
70.00
2.90
1.18
0.00
72.00
2.90
1.18
0.00
74.00
2.90
1.18
0.00
76.00
2.90
1.18
0.00
78.00
2.90
1.18
0.00
80.00
2.90
1.18
0.00
82.00
2.90
1.18
0.00
84.00
2.90
1.18
0.00
86.00
2.90
1.18
0.00
88.00
2.90
1.18
0.00
90.00
2.90
1.18
0.00
92.00
2.90
1.18
0.00
94.00
2.90
1.18
0.00
96.00
2.90
1.18
0.00
98.00
2.90
1.18
0.00
100.00
2.90
1.18
0.00
102.00
2.90
1.18
0.00
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
104.00
2.90
1.18
0.00
106.00
2.90
1.18
0.00
108.00
2.90
1.18
0.00
110.00
2.90
1.18
0.00
112.00
2.90
1.18
0.00
114.00
2.90
1.18
0.00
116.00
2.90
1.18
0.00
118.00
2.90
1.18
0.00
120.00
2.90
1.18
0.00
122.00
2.90
1.18
0.00
124.00
2.90
1.18
0.00
126.00
2.90
1.18
0.00
128.00
2.90
1.18
0.00
130.00
2.90
1.18
0.00
132.00
2.90
1.18
0.00
134.00
2.90
1.18
0.00
136.00
2.90
1.18
0.00
138.00
2.90
1.18
0.00
140.00
2.90
1.18
0.00
142.00
2.90
1.18
0.00
144.00
2.90
1.18
0.00
146.00
2.90
1.18
0.00
148.00
2.90
1.18
0.00
150.00
2.90
1.18
0.00
152.00
2.90
1.18
0.00
154.00
2.90
1.18
0.00
156.00
2.90
1.18
0.00
158.00
2.90
1.18
0.00
160.00
2.90
1.18
0.00
162.00
2.90
1.18
0.00
164.00
2.90
1.18
0.00
166.00
2.90
1.18
0.00
168.00
2.90
1.18
0.00
170.00
2.90
1.18
0.00
172.00
2.90
1.18
0.00
174.00
2.90
1.18
0.00
176.00
2.90
1.18
0.00
178.00
2.90
1.18
0.00
180.00
2.90
1.18
0.00
182.00
2.90
1.18
0.00
184.00
2.90
1.18
0.00
186.00
2.90
1.18
0.00
188.00
2.90
1.18
0.00
190.00
2.90
1.18
0.00
192.00
2.90
1.18
0.00
194.00
2.90
1.18
0.00
196.00
2.90
1.18
0.00
198.00
2.90
1.18
0.00
200.00
2.90
1.18
0.00

2020.17-BMP1 REVISED
Type 11 24-hr 1-yr Concord Rainfall=2.90"
Prepared by {enter your company name here} Page 8
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/4/2022
Pond 3P: (BMP1)
Inflow Area = 17.860 ac, Inflow Depth = 1.18" for 1-yr Concord event
Inflow =
39.11 cfs @
11.96 hrs,
Volume=
1.750 of
Outflow =
0.94 cfs @
15.67 hrs,
Volume=
1.749 af, Atten= 98%, Lag= 222.4 min
Primary =
0.94 cfs @
15.67 hrs,
Volume=
1.749 of
Secondary =
0.00 cfs @
0.00 hrs,
Volume=
0.000 of
Routing by Stor-Ind method, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Peak Elev= 611.71' @ 15.67 hrs Surf.Area= 20,003 sf Storage= 48,260 cf
Plug -Flow detention time= 1,382.8 min calculated for 1.749 of (100% of inflow)
Center -of -Mass det. time= 1,382.5 min ( 2,226.2 - 843.7 )
Volume Invert
Avail.Storage Storage Description
#1 609.00'
150,165 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area
Inc.Store Cum.Store
(feet)
(sq-ft)
(cubic -feet) (cubic -feet)
609.00
15,725
0 0
610.00
17,253
16,489 16,489
612.00
20,478
37,731 54,220
614.00
23,930
44,408 98,628
616.00
27,607
51,537 150,165
Device Routing
Invert
Outlet Devices
#1 Primary
606.40'
24.0" x 60.0' long Culvert RCP, square edge headwall, Ke= 0.500
Outlet Invert= 606.00' S= 0.0067 7' Cc= 0.900 n= 0.013
#2 Device 1
609.00'
Exfiltration
Head (feet) 0.00 1.00 2.00 3.00 4.00 5.00 6.00
Disch. (cfs) 0.000 0.178 0.249 0.321 0.392 0.463 0.534
#3 Device 1
611.00'
6.0" Vert. Orifice/Grate C= 0.600
#4 Device 1
614.00'
2.00' x 3.00' Horiz. Top of Riser Limited to weir flow C= 0.600
#5 Secondary
615.00'
10.0' long x 16.0' breadth Spillway
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Coef. (English) 2.68 2.70 2.70 2.64 2.63 2.64 2.64 2.63
Primary OutFlow Max=0.94 cfs @ 15.67 hrs HW=611.71' (Free Discharge)
L1=Culvert (Passes 0.94 cfs of 31.39 cfs potential flow)
2=Exfltration (Custom Controls 0.30 cfs)
3=Orifice/Grate (Orifice Controls 0.64 cfs @ 3.25 fps)
=Top of Riser ( Controls 0.00 cfs)
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=609.00' (Free Discharge)
5=Spillway ( Controls 0.00 cfs)

2020.17-BMP1 REVISED
Type // 24-hr 1-yr Concord Rainfall=2.90"
Prepared by {enter your company name here} Page 9
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/4/2022
Hydrograph for Pond 3P: (BMP1)
Time
Inflow
Storage
Elevation
Outflow
Primary
Secondary
(hours)
(cfs)
(cubic -feet)
(feet)
(cfs)
(cfs)
(cfs)
0.00
0.00
0
609.00
0.00
0.00
0.00
5.00
0.00
0
609.00
0.00
0.00
0.00
10.00
0.03
7
609.00
0.00
0.00
0.00
15.00
1.10
48,062
611.70
0.93
0.93
0.00
20.00
0.50
45,204
611.55
0.81
0.81
0.00
25.00
0.00
39,879
611.28
0.47
0.47
0.00
30.00
0.00
34,211
610.98
0.25
0.25
0.00
35.00
0.00
29,901
610.75
0.23
0.23
0.00
40.00
0.00
25,879
610.53
0.22
0.22
0.00
45.00
0.00
22,131
610.32
0.20
0.20
0.00
50.00
0.00
18,643
610.12
0.19
0.19
0.00
55.00
0.00
15,421
609.94
0.17
0.17
0.00
60.00
0.00
12,682
609.78
0.14
0.14
0.00
65.00
0.00
10,414
609.64
0.11
0.11
0.00
70.00
0.00
8,543
609.53
0.09
0.09
0.00
75.00
0.00
7,000
609.44
0.08
0.08
0.00
80.00
0.00
5,732
609.36
0.06
0.06
0.00
85.00
0.00
4,690
609.29
0.05
0.05
0.00
90.00
0.00
3,836
609.24
0.04
0.04
0.00
95.00
0.00
3,136
609.20
0.04
0.04
0.00
100.00
0.00
2,562
609.16
0.03
0.03
0.00
105.00
0.00
2,093
609.13
0.02
0.02
0.00
110.00
0.00
1,709
609.11
0.02
0.02
0.00
115.00
0.00
1,396
609.09
0.02
0.02
0.00
120.00
0.00
1,139
609.07
0.01
0.01
0.00
125.00
0.00
930
609.06
0.01
0.01
0.00
130.00
0.00
759
609.05
0.01
0.01
0.00
135.00
0.00
620
609.04
0.01
0.01
0.00
140.00
0.00
506
609.03
0.01
0.01
0.00
145.00
0.00
413
609.03
0.00
0.00
0.00
150.00
0.00
337
609.02
0.00
0.00
0.00
155.00
0.00
275
609.02
0.00
0.00
0.00
160.00
0.00
224
609.01
0.00
0.00
0.00
165.00
0.00
183
609.01
0.00
0.00
0.00
170.00
0.00
150
609.01
0.00
0.00
0.00
175.00
0.00
122
609.01
0.00
0.00
0.00
180.00
0.00
100
609.01
0.00
0.00
0.00
185.00
0.00
81
609.01
0.00
0.00
0.00
190.00
0.00
66
609.00
0.00
0.00
0.00
195.00
0.00
54
609.00
0.00
0.00
0.00
200.00
0.00
44
609.00
0.00
0.00
0.00

2020.17-BMP1 REVISED
Type 11 24-hr 1-yr Concord Rainfall=2.90"
Prepared by {enter your company name here} Page 10
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/4/2022
Stage -Discharge for Pond 3P: (BMP1)
Elevation Discharge Primary Secondary
(feet)
(cfs)
(cfs)
(cfs)
609.00
0.00
0.00
0.00
609.10
0.02
0.02
0.00
609.20
0.04
0.04
0.00
609.30
0.05
0.05
0.00
609.40
0.07
0.07
0.00
609.50
0.09
0.09
0.00
609.60
0.11
0.11
0.00
609.70
0.12
0.12
0.00
609.80
0.14
0.14
0.00
609.90
0.16
0.16
0.00
610.00
0.18
0.18
0.00
610.10
0.19
0.19
0.00
610.20
0.19
0.19
0.00
610.30
0.20
0.20
0.00
610.40
0.21
0.21
0.00
610.50
0.21
0.21
0.00
610.60
0.22
0.22
0.00
610.70
0.23
0.23
0.00
610.80
0.23
0.23
0.00
610.90
0.24
0.24
0.00
611.00
0.25
0.25
0.00
611.10
0.29
0.29
0.00
611.20
0.38
0.38
0.00
611.30
0.50
0.50
0.00
611.40
0.64
0.64
0.00
611.50
0.76
0.76
0.00
611.60
0.85
0.85
0.00
611.70
0.93
0.93
0.00
611.80
1.01
1.01
0.00
611.90
1.08
1.08
0.00
612.00
1.14
1.14
0.00
612.10
1.20
1.20
0.00
612.20
1.26
1.26
0.00
612.30
1.31
1.31
0.00
612.40
1.36
1.36
0.00
612.50
1.41
1.41
0.00
612.60
1.46
1.46
0.00
612.70
1.51
1.51
0.00
612.80
1.55
1.55
0.00
612.90
1.60
1.60
0.00
613.00
1.64
1.64
0.00
613.10
1.69
1.69
0.00
613.20
1.73
1.73
0.00
613.30
1.77
1.77
0.00
613.40
1.81
1.81
0.00
613.50
1.85
1.85
0.00
613.60
1.88
1.88
0.00
613.70
1.92
1.92
0.00
613.80
1.96
1.96
0.00
613.90
1.99
1.99
0.00
614.00
2.03
2.03
0.00
614.10
3.10
3.10
0.00
Elevation Discharge Primary Secondary
(feet)
(cfs)
(cfs)
(cfs)
614.20
5.03
5.03
0.00
614.30
7.51
7.51
0.00
614.40
10.44
10.44
0.00
614.50
13.76
13.76
0.00
614.60
17.43
17.43
0.00
614.70
21.42
21.42
0.00
614.80
25.70
25.70
0.00
614.90
29.74
29.74
0.00
615.00
31.25
31.25
0.00
615.10
33.54
32.69
0.85
615.20
36.46
34.06
2.40
615.30
39.80
35.38
4.42
615.40
43.47
36.64
6.83
615.50
47.41
37.87
9.55
615.60
51.60
39.05
12.55
615.70
55.83
40.20
15.64
615.80
60.20
41.31
18.89
615.90
64.89
42.39
22.50
616.00
69.75
43.45
26.30

2020.17-BMP1 REVISED
Type 11 24-hr 1-yr Concord Rainfall=2.90"
Prepared by {enter your company name here} Page 11
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/4/2022
Stage -Area -Storage for Pond 3P: (BMP1)
Elevation
Surface
Storage
(feet)
(sq-ft)
(cubic -feet)
609.00
15,725
0
609.10
15,878
1,580
609.20
16,031
3,176
609.30
16,183
4,786
609.40
16,336
6,412
609.50
16,489
8,054
609.60
16,642
9,710
609.70
16,795
11,382
609.80
16,947
13,069
609.90
17,100
14,771
610.00
17,253
16,489
610.10
17,414
18,222
610.20
17,576
19,972
610.30
17,737
21,737
610.40
17,898
23,519
610.50
18,059
25,317
610.60
18,221
27,131
610.70
18,382
28,961
610.80
18,543
30,807
610.90
18,704
32,670
611.00
18,866
34,548
611.10
19,027
36,443
611.20
19,188
38,354
611.30
19,349
40,280
611.40
19,510
42,223
611.50
19,672
44,183
611.60
19,833
46,158
611.70
19,994
48,149
611.80
20,155
50,157
611.90
20,317
52,180
612.00
20,478
54,220
612.10
20,651
56,276
612.20
20,823
58,350
612.30
20,996
60,441
612.40
21,168
62,549
612.50
21,341
64,675
612.60
21,514
66,817
612.70
21,686
68,977
612.80
21,859
71,155
612.90
22,031
73,349
613.00
22,204
75,561
613.10
22,377
77,790
613.20
22,549
80,036
613.30
22,722
82,300
613.40
22,894
84,581
613.50
23,067
86,879
613.60
23,240
89,194
613.70
23,412
91,527
613.80
23,585
93,877
613.90
23,757
96,244
614.00
23,930
98,628
614.10
24,114
101,030
Elevation
Surface
Storage
(feet)
(sq-ft)
(cubic -feet)
614.20
24,298
103,451
614.30
24,482
105,890
614.40
24,665
108,347
614.50
24,849
110,823
614.60
25,033
113,317
614.70
25,217
115,829
614.80
25,401
118,360
614.90
25,585
120,910
615.00
25,769
123,477
615.10
25,952
126,063
615.20
26,136
128,668
615.30
26,320
131,291
615.40
26,504
133,932
615.50
26,688
136,591
615.60
26,872
139,269
615.70
27,055
141,966
615.80
27,239
144,680
615.90
27,423
147,413
616.00
27,607
150,165

2020.17-BMP1 REVISED Type 11 24-hr 10-yr Concord Rainfall=5.10"
Prepared by {enter your company name here} Page 12
HvdroCAD® 8.00 s/n 004317 © 2006 HvdroCAD Software Solutions LLC 6/4/2022
Time span=0.00-200.00 hrs, dt=0.01 hrs, 20001 points
Runoff by SCS TR-20 method, UH=SCS
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment 1S: (Predeveloped) Runoff Area=17.860 ac Runoff Depth=2.28"
Flow Length=1,107' Tc=22.5 min CN=72 Runoff=41.73 cfs 3.386 of
Subcatchment 2S: (Post Developed) Runoff Area=17.860 ac Runoff Depth=2.98"
Tc=5.0 min CN=80 Runoff=97.31 cfs 4.436 of
Pond 3P: (BMP1) Peak Elev=614.32' Storage=106,299 cf Inflow=97.31 cfs 4.436 of
Primary=7.97 cfs 4.434 of Secondary=0.00 cfs 0.000 of Outflow=7.97 cfs 4.434 of
Total Runoff Area = 35.720 ac Runoff Volume = 7.822 of Average Runoff Depth = 2.63"
100.00% Pervious Area = 35.720 ac 0.00% Impervious Area = 0.000 ac

2020.17-BMP1 REVISED
Type 11 24-hr 10-yr Concord Rainfall=5.10"
Prepared by {enter your company name here} Page 13
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/4/2022
Subcatchment 1S: (Predeveloped)
BASED ON EXISTING CONDITIONS
Runoff = 41.73 cfs @ 12.17 hrs, Volume= 3.386 af, Depth= 2.28"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Type II 24-hr 10-yr Concord Rainfall=5.10"
Area (ac)
CN
Description
3.200
73
Woods, Fair, HSG C
3.600
60
Woods, Fair, HSG B
3.500
69
Pasture/grassland/range, Fair, HSG B
7.560
79
Pasture/grassland/range, Fair, HSG C
17.860
72
Weighted Average
17.860
Pervious Area
Tc
Length
Slope
Velocity
Capacity Description
(min)
(feet)
(ft/ft)
(ft/sec)
(cfs)
10.7
100
0.0371
0.16
Sheet Flow,
Grass: Dense n= 0.240 P2= 3.50"
6.6
719
0.0672
1.81
Shallow Concentrated Flow,
Short Grass Pasture Kv= 7.0 fps
5.2
288
0.0347
0.93
Shallow Concentrated Flow,
Woodland Kv= 5.0 fps
22.5 1,107 Total

2020.17-BMP1 REVISED
Type 11 24-hr 10-yr Concord Rainfall=5.10"
Prepared by {enter your company name here} Page 14
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/4/2022
Hydrograph for Subcatchment 1S: (Predeveloped)
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
0.00
0.00
0.00
0.00
2.00
0.11
0.00
0.00
4.00
0.24
0.00
0.00
6.00
0.41
0.00
0.00
8.00
0.61
0.00
0.00
10.00
0.92
0.01
0.13
12.00
3.38
1.04
23.80
14.00
4.18
1.59
2.87
16.00
4.49
1.81
1.72
18.00
4.70
1.97
1.30
20.00
4.86
2.09
0.97
22.00
4.98
2.18
0.86
24.00
5.10
2.28
0.79
26.00
5.10
2.28
0.00
28.00
5.10
2.28
0.00
30.00
5.10
2.28
0.00
32.00
5.10
2.28
0.00
34.00
5.10
2.28
0.00
36.00
5.10
2.28
0.00
38.00
5.10
2.28
0.00
40.00
5.10
2.28
0.00
42.00
5.10
2.28
0.00
44.00
5.10
2.28
0.00
46.00
5.10
2.28
0.00
48.00
5.10
2.28
0.00
50.00
5.10
2.28
0.00
52.00
5.10
2.28
0.00
54.00
5.10
2.28
0.00
56.00
5.10
2.28
0.00
58.00
5.10
2.28
0.00
60.00
5.10
2.28
0.00
62.00
5.10
2.28
0.00
64.00
5.10
2.28
0.00
66.00
5.10
2.28
0.00
68.00
5.10
2.28
0.00
70.00
5.10
2.28
0.00
72.00
5.10
2.28
0.00
74.00
5.10
2.28
0.00
76.00
5.10
2.28
0.00
78.00
5.10
2.28
0.00
80.00
5.10
2.28
0.00
82.00
5.10
2.28
0.00
84.00
5.10
2.28
0.00
86.00
5.10
2.28
0.00
88.00
5.10
2.28
0.00
90.00
5.10
2.28
0.00
92.00
5.10
2.28
0.00
94.00
5.10
2.28
0.00
96.00
5.10
2.28
0.00
98.00
5.10
2.28
0.00
100.00
5.10
2.28
0.00
102.00
5.10
2.28
0.00
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
104.00
5.10
2.28
0.00
106.00
5.10
2.28
0.00
108.00
5.10
2.28
0.00
110.00
5.10
2.28
0.00
112.00
5.10
2.28
0.00
114.00
5.10
2.28
0.00
116.00
5.10
2.28
0.00
118.00
5.10
2.28
0.00
120.00
5.10
2.28
0.00
122.00
5.10
2.28
0.00
124.00
5.10
2.28
0.00
126.00
5.10
2.28
0.00
128.00
5.10
2.28
0.00
130.00
5.10
2.28
0.00
132.00
5.10
2.28
0.00
134.00
5.10
2.28
0.00
136.00
5.10
2.28
0.00
138.00
5.10
2.28
0.00
140.00
5.10
2.28
0.00
142.00
5.10
2.28
0.00
144.00
5.10
2.28
0.00
146.00
5.10
2.28
0.00
148.00
5.10
2.28
0.00
150.00
5.10
2.28
0.00
152.00
5.10
2.28
0.00
154.00
5.10
2.28
0.00
156.00
5.10
2.28
0.00
158.00
5.10
2.28
0.00
160.00
5.10
2.28
0.00
162.00
5.10
2.28
0.00
164.00
5.10
2.28
0.00
166.00
5.10
2.28
0.00
168.00
5.10
2.28
0.00
170.00
5.10
2.28
0.00
172.00
5.10
2.28
0.00
174.00
5.10
2.28
0.00
176.00
5.10
2.28
0.00
178.00
5.10
2.28
0.00
180.00
5.10
2.28
0.00
182.00
5.10
2.28
0.00
184.00
5.10
2.28
0.00
186.00
5.10
2.28
0.00
188.00
5.10
2.28
0.00
190.00
5.10
2.28
0.00
192.00
5.10
2.28
0.00
194.00
5.10
2.28
0.00
196.00
5.10
2.28
0.00
198.00
5.10
2.28
0.00
200.00
5.10
2.28
0.00

2020.17-BMP1 REVISED Type 11 24-hr 10-yr Concord Rainfall=5.10"
Prepared by {enter your company name here} Page 15
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/4/2022
Subcatchment 2S: (Post Developed)
Runoff = 97.31 cfs @ 11.96 hrs, Volume= 4.436 af, Depth= 2.98"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Type II 24-hr 10-yr Concord Rainfall=5.10"
Area (ac) CN
Description
10.770 83
RM-2 (C)
7.090 75
RM-2 (B)
17.860 80
Weighted Average
17.860
Pervious Area
Tc Length
Slope Velocity Capacity Description
(min) (feet)
(ft/ft) (ft/sec) (cfs)
5.0
Direct Entry,

2020.17-BMP1 REVISED
Type 11 24-hr 10-yr Concord Rainfall=5.10"
Prepared by {enter your company name here} Page 16
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/4/2022
Hydrograph for Subcatchment 2S: (Post Developed)
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
0.00
0.00
0.00
0.00
2.00
0.11
0.00
0.00
4.00
0.24
0.00
0.00
6.00
0.41
0.00
0.00
8.00
0.61
0.00
0.16
10.00
0.92
0.06
0.93
12.00
3.38
1.54
83.03
14.00
4.18
2.19
2.96
16.00
4.49
2.45
1.84
18.00
4.70
2.63
1.44
20.00
4.86
2.77
1.05
22.00
4.98
2.88
0.96
24.00
5.10
2.98
0.89
26.00
5.10
2.98
0.00
28.00
5.10
2.98
0.00
30.00
5.10
2.98
0.00
32.00
5.10
2.98
0.00
34.00
5.10
2.98
0.00
36.00
5.10
2.98
0.00
38.00
5.10
2.98
0.00
40.00
5.10
2.98
0.00
42.00
5.10
2.98
0.00
44.00
5.10
2.98
0.00
46.00
5.10
2.98
0.00
48.00
5.10
2.98
0.00
50.00
5.10
2.98
0.00
52.00
5.10
2.98
0.00
54.00
5.10
2.98
0.00
56.00
5.10
2.98
0.00
58.00
5.10
2.98
0.00
60.00
5.10
2.98
0.00
62.00
5.10
2.98
0.00
64.00
5.10
2.98
0.00
66.00
5.10
2.98
0.00
68.00
5.10
2.98
0.00
70.00
5.10
2.98
0.00
72.00
5.10
2.98
0.00
74.00
5.10
2.98
0.00
76.00
5.10
2.98
0.00
78.00
5.10
2.98
0.00
80.00
5.10
2.98
0.00
82.00
5.10
2.98
0.00
84.00
5.10
2.98
0.00
86.00
5.10
2.98
0.00
88.00
5.10
2.98
0.00
90.00
5.10
2.98
0.00
92.00
5.10
2.98
0.00
94.00
5.10
2.98
0.00
96.00
5.10
2.98
0.00
98.00
5.10
2.98
0.00
100.00
5.10
2.98
0.00
102.00
5.10
2.98
0.00
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
104.00
5.10
2.98
0.00
106.00
5.10
2.98
0.00
108.00
5.10
2.98
0.00
110.00
5.10
2.98
0.00
112.00
5.10
2.98
0.00
114.00
5.10
2.98
0.00
116.00
5.10
2.98
0.00
118.00
5.10
2.98
0.00
120.00
5.10
2.98
0.00
122.00
5.10
2.98
0.00
124.00
5.10
2.98
0.00
126.00
5.10
2.98
0.00
128.00
5.10
2.98
0.00
130.00
5.10
2.98
0.00
132.00
5.10
2.98
0.00
134.00
5.10
2.98
0.00
136.00
5.10
2.98
0.00
138.00
5.10
2.98
0.00
140.00
5.10
2.98
0.00
142.00
5.10
2.98
0.00
144.00
5.10
2.98
0.00
146.00
5.10
2.98
0.00
148.00
5.10
2.98
0.00
150.00
5.10
2.98
0.00
152.00
5.10
2.98
0.00
154.00
5.10
2.98
0.00
156.00
5.10
2.98
0.00
158.00
5.10
2.98
0.00
160.00
5.10
2.98
0.00
162.00
5.10
2.98
0.00
164.00
5.10
2.98
0.00
166.00
5.10
2.98
0.00
168.00
5.10
2.98
0.00
170.00
5.10
2.98
0.00
172.00
5.10
2.98
0.00
174.00
5.10
2.98
0.00
176.00
5.10
2.98
0.00
178.00
5.10
2.98
0.00
180.00
5.10
2.98
0.00
182.00
5.10
2.98
0.00
184.00
5.10
2.98
0.00
186.00
5.10
2.98
0.00
188.00
5.10
2.98
0.00
190.00
5.10
2.98
0.00
192.00
5.10
2.98
0.00
194.00
5.10
2.98
0.00
196.00
5.10
2.98
0.00
198.00
5.10
2.98
0.00
200.00
5.10
2.98
0.00

2020.17-BMP1 REVISED
Type 11 24-hr 10-yr Concord Rainfall=5.10"
Prepared by {enter your company name here} Page 17
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/4/2022
Pond 3P: (BMP1)
Inflow Area = 17.860 ac, Inflow Depth = 2.98" for 10-yr Concord event
Inflow =
97.31 cfs @
11.96 hrs,
Volume=
4.436 of
Outflow =
7.97 cfs @
12.49 hrs,
Volume=
4.434 af, Atten= 92%, Lag= 31.6 min
Primary =
7.97 cfs @
12.49 hrs,
Volume=
4.434 of
Secondary =
0.00 cfs @
0.00 hrs,
Volume=
0.000 of
Routing by Stor-Ind method, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Peak Elev= 614.32' @ 12.49 hrs Surf.Area= 24,512 sf Storage= 106,299 cf
Plug -Flow detention time= 891.5 min calculated for 4.434 of (100% of inflow)
Center -of -Mass det. time= 891.3 min ( 1,708.2 - 816.9 )
Volume Invert
Avail.Storage Storage Description
#1 609.00'
150,165 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area
Inc.Store Cum.Store
(feet)
(sq-ft)
(cubic -feet) (cubic -feet)
609.00
15,725
0 0
610.00
17,253
16,489 16,489
612.00
20,478
37,731 54,220
614.00
23,930
44,408 98,628
616.00
27,607
51,537 150,165
Device Routing
Invert
Outlet Devices
#1 Primary
606.40'
24.0" x 60.0' long Culvert RCP, square edge headwall, Ke= 0.500
Outlet Invert= 606.00' S= 0.0067 7' Cc= 0.900 n= 0.013
#2 Device 1
609.00'
Exfiltration
Head (feet) 0.00 1.00 2.00 3.00 4.00 5.00 6.00
Disch. (cfs) 0.000 0.178 0.249 0.321 0.392 0.463 0.534
#3 Device 1
611.00'
6.0" Vert. Orifice/Grate C= 0.600
#4 Device 1
614.00'
2.00' x 3.00' Horiz. Top of Riser Limited to weir flow C= 0.600
#5 Secondary
615.00'
10.0' long x 16.0' breadth Spillway
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Coef. (English) 2.68 2.70 2.70 2.64 2.63 2.64 2.64 2.63
Primary OutFlow Max=7.97 cfs @ 12.49 hrs HW=614.32' (Free Discharge)
L1=Culvert (Passes 7.97 cfs of 39.78 cfs potential flow)
2=Exfltration (Custom Controls 0.49 cfs)
3=Orifice/Grate (Orifice Controls 1.66 cfs @ 8.43 fps)
=Top of Riser (Weir Controls 5.83 cfs @ 1.84 fps)
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=609.00' (Free Discharge)
5=Spillway ( Controls 0.00 cfs)

2020.17-BMP1 REVISED
Type 11 24-hr 10-yr Concord Rainfall=5.10"
Prepared by {enter your company name here} Page 18
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/4/2022
Hydrograph for Pond 3P: (BMP1)
Time
Inflow
Storage
Elevation
Outflow
Primary
Secondary
(hours)
(cfs)
(cubic -feet)
(feet)
(cfs)
(cfs)
(cfs)
0.00
0.00
0
609.00
0.00
0.00
0.00
5.00
0.00
0
609.00
0.00
0.00
0.00
10.00
0.93
3,581
609.23
0.04
0.04
0.00
15.00
2.37
100,216
614.07
2.66
2.66
0.00
20.00
1.05
91,097
613.68
1.91
1.91
0.00
25.00
0.00
73,188
612.89
1.60
1.60
0.00
30.00
0.00
49,779
611.78
0.99
0.99
0.00
35.00
0.00
38,003
611.18
0.36
0.36
0.00
40.00
0.00
33,087
610.92
0.24
0.24
0.00
45.00
0.00
28,851
610.69
0.23
0.23
0.00
50.00
0.00
24,900
610.48
0.21
0.21
0.00
55.00
0.00
21,220
610.27
0.20
0.20
0.00
60.00
0.00
17,796
610.08
0.18
0.18
0.00
65.00
0.00
14,675
609.89
0.16
0.16
0.00
70.00
0.00
12,064
609.74
0.13
0.13
0.00
75.00
0.00
9,904
609.61
0.11
0.11
0.00
80.00
0.00
8,122
609.50
0.09
0.09
0.00
85.00
0.00
6,654
609.41
0.07
0.07
0.00
90.00
0.00
5,448
609.34
0.06
0.06
0.00
95.00
0.00
4,457
609.28
0.05
0.05
0.00
100.00
0.00
3,645
609.23
0.04
0.04
0.00
105.00
0.00
2,979
609.19
0.03
0.03
0.00
110.00
0.00
2,434
609.15
0.03
0.03
0.00
115.00
0.00
1,988
609.13
0.02
0.02
0.00
120.00
0.00
1,624
609.10
0.02
0.02
0.00
125.00
0.00
1,326
609.08
0.01
0.01
0.00
130.00
0.00
1,082
609.07
0.01
0.01
0.00
135.00
0.00
883
609.06
0.01
0.01
0.00
140.00
0.00
721
609.05
0.01
0.01
0.00
145.00
0.00
588
609.04
0.01
0.01
0.00
150.00
0.00
480
609.03
0.01
0.01
0.00
155.00
0.00
392
609.02
0.00
0.00
0.00
160.00
0.00
320
609.02
0.00
0.00
0.00
165.00
0.00
261
609.02
0.00
0.00
0.00
170.00
0.00
213
609.01
0.00
0.00
0.00
175.00
0.00
174
609.01
0.00
0.00
0.00
180.00
0.00
142
609.01
0.00
0.00
0.00
185.00
0.00
116
609.01
0.00
0.00
0.00
190.00
0.00
95
609.01
0.00
0.00
0.00
195.00
0.00
77
609.00
0.00
0.00
0.00
200.00
0.00
63
609.00
0.00
0.00
0.00

2020.17-BMP1 REVISED
Type 11 24-hr 10-yr Concord Rainfall=5.10"
Prepared by {enter your company name here} Page 19
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/4/2022
Stage -Discharge for Pond 3P: (BMP1)
Elevation Discharge Primary Secondary
(feet)
(cfs)
(cfs)
(cfs)
609.00
0.00
0.00
0.00
609.10
0.02
0.02
0.00
609.20
0.04
0.04
0.00
609.30
0.05
0.05
0.00
609.40
0.07
0.07
0.00
609.50
0.09
0.09
0.00
609.60
0.11
0.11
0.00
609.70
0.12
0.12
0.00
609.80
0.14
0.14
0.00
609.90
0.16
0.16
0.00
610.00
0.18
0.18
0.00
610.10
0.19
0.19
0.00
610.20
0.19
0.19
0.00
610.30
0.20
0.20
0.00
610.40
0.21
0.21
0.00
610.50
0.21
0.21
0.00
610.60
0.22
0.22
0.00
610.70
0.23
0.23
0.00
610.80
0.23
0.23
0.00
610.90
0.24
0.24
0.00
611.00
0.25
0.25
0.00
611.10
0.29
0.29
0.00
611.20
0.38
0.38
0.00
611.30
0.50
0.50
0.00
611.40
0.64
0.64
0.00
611.50
0.76
0.76
0.00
611.60
0.85
0.85
0.00
611.70
0.93
0.93
0.00
611.80
1.01
1.01
0.00
611.90
1.08
1.08
0.00
612.00
1.14
1.14
0.00
612.10
1.20
1.20
0.00
612.20
1.26
1.26
0.00
612.30
1.31
1.31
0.00
612.40
1.36
1.36
0.00
612.50
1.41
1.41
0.00
612.60
1.46
1.46
0.00
612.70
1.51
1.51
0.00
612.80
1.55
1.55
0.00
612.90
1.60
1.60
0.00
613.00
1.64
1.64
0.00
613.10
1.69
1.69
0.00
613.20
1.73
1.73
0.00
613.30
1.77
1.77
0.00
613.40
1.81
1.81
0.00
613.50
1.85
1.85
0.00
613.60
1.88
1.88
0.00
613.70
1.92
1.92
0.00
613.80
1.96
1.96
0.00
613.90
1.99
1.99
0.00
614.00
2.03
2.03
0.00
614.10
3.10
3.10
0.00
Elevation Discharge Primary Secondary
(feet)
(cfs)
(cfs)
(cfs)
614.20
5.03
5.03
0.00
614.30
7.51
7.51
0.00
614.40
10.44
10.44
0.00
614.50
13.76
13.76
0.00
614.60
17.43
17.43
0.00
614.70
21.42
21.42
0.00
614.80
25.70
25.70
0.00
614.90
29.74
29.74
0.00
615.00
31.25
31.25
0.00
615.10
33.54
32.69
0.85
615.20
36.46
34.06
2.40
615.30
39.80
35.38
4.42
615.40
43.47
36.64
6.83
615.50
47.41
37.87
9.55
615.60
51.60
39.05
12.55
615.70
55.83
40.20
15.64
615.80
60.20
41.31
18.89
615.90
64.89
42.39
22.50
616.00
69.75
43.45
26.30

2020.17-BMP1 REVISED
Type // 24-hr 10-yr Concord Rainfall=5.10"
Prepared by {enter your company name here} Page 20
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/4/2022
Stage -Area -Storage for Pond 3P: (BMP1)
Elevation
Surface
Storage
(feet)
(sq-ft)
(cubic -feet)
609.00
15,725
0
609.10
15,878
1,580
609.20
16,031
3,176
609.30
16,183
4,786
609.40
16,336
6,412
609.50
16,489
8,054
609.60
16,642
9,710
609.70
16,795
11,382
609.80
16,947
13,069
609.90
17,100
14,771
610.00
17,253
16,489
610.10
17,414
18,222
610.20
17,576
19,972
610.30
17,737
21,737
610.40
17,898
23,519
610.50
18,059
25,317
610.60
18,221
27,131
610.70
18,382
28,961
610.80
18,543
30,807
610.90
18,704
32,670
611.00
18,866
34,548
611.10
19,027
36,443
611.20
19,188
38,354
611.30
19,349
40,280
611.40
19,510
42,223
611.50
19,672
44,183
611.60
19,833
46,158
611.70
19,994
48,149
611.80
20,155
50,157
611.90
20,317
52,180
612.00
20,478
54,220
612.10
20,651
56,276
612.20
20,823
58,350
612.30
20,996
60,441
612.40
21,168
62,549
612.50
21,341
64,675
612.60
21,514
66,817
612.70
21,686
68,977
612.80
21,859
71,155
612.90
22,031
73,349
613.00
22,204
75,561
613.10
22,377
77,790
613.20
22,549
80,036
613.30
22,722
82,300
613.40
22,894
84,581
613.50
23,067
86,879
613.60
23,240
89,194
613.70
23,412
91,527
613.80
23,585
93,877
613.90
23,757
96,244
614.00
23,930
98,628
614.10
24,114
101,030
Elevation
Surface
Storage
(feet)
(sq-ft)
(cubic -feet)
614.20
24,298
103,451
614.30
24,482
105,890
614.40
24,665
108,347
614.50
24,849
110,823
614.60
25,033
113,317
614.70
25,217
115,829
614.80
25,401
118,360
614.90
25,585
120,910
615.00
25,769
123,477
615.10
25,952
126,063
615.20
26,136
128,668
615.30
26,320
131,291
615.40
26,504
133,932
615.50
26,688
136,591
615.60
26,872
139,269
615.70
27,055
141,966
615.80
27,239
144,680
615.90
27,423
147,413
616.00
27,607
150,165

2020.17-BMP1 REVISED Type/1 24-hr 25-yr Concord Rainfall=6.00"
Prepared by {enter your company name here} Page 21
HvdroCAD® 8.00 s/n 004317 © 2006 HvdroCAD Software Solutions LLC 6/4/2022
Time span=0.00-200.00 hrs, dt=0.01 hrs, 20001 points
Runoff by SCS TR-20 method, UH=SCS
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment 1S: (Predeveloped) Runoff Area=17.860 ac Runoff Depth=2.99"
Flow Length=1,107' Tc=22.5 min CN=72 Runoff=55.29 cfs 4.455 of
Subcatchment 2S: (Post Developed) Runoff Area=17.860 ac Runoff Depth=3.78"
Tc=5.0 min CN=80 Runoff=122.16 cfs 5.628 of
Pond 3P: (BMP1) Peak Elev=614.88' Storage=120,391 cf Inflow=122.16 cfs 5.628 of
Primary=29.31 cfs 5.626 of Secondary=0.00 cfs 0.000 of Outflow=29.31 cfs 5.626 of
Total Runoff Area = 35.720 ac Runoff Volume = 10.083 of Average Runoff Depth = 3.39"
100.00% Pervious Area = 35.720 ac 0.00% Impervious Area = 0.000 ac

2020.17-BMP1 REVISED
Type/1 24-hr 25-yr Concord Rainfall=6.00"
Prepared by {enter your company name here} Page 22
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/4/2022
Subcatchment 1S: (Predeveloped)
BASED ON EXISTING CONDITIONS
Runoff = 55.29 cfs @ 12.16 hrs, Volume= 4.455 af, Depth= 2.99"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Type II 24-hr 25-yr Concord Rainfall=6.00"
Area (ac)
CN
Description
3.200
73
Woods, Fair, HSG C
3.600
60
Woods, Fair, HSG B
3.500
69
Pasture/grassland/range, Fair, HSG B
7.560
79
Pasture/grassland/range, Fair, HSG C
17.860
72
Weighted Average
17.860
Pervious Area
Tc
Length
Slope
Velocity
Capacity Description
(min)
(feet)
(ft/ft)
(ft/sec)
(cfs)
10.7
100
0.0371
0.16
Sheet Flow,
Grass: Dense n= 0.240 P2= 3.50"
6.6
719
0.0672
1.81
Shallow Concentrated Flow,
Short Grass Pasture Kv= 7.0 fps
5.2
288
0.0347
0.93
Shallow Concentrated Flow,
Woodland Kv= 5.0 fps
22.5 1,107 Total

2020.17-BMP1 REVISED
Type // 24-hr 25-yr Concord Rainfall=6.00"
Prepared by {enter your company name here} Page 23
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/4/2022
Hydrograph for Subcatchment 1S: (Predeveloped)
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
0.00
0.00
0.00
0.00
2.00
0.13
0.00
0.00
4.00
0.29
0.00
0.00
6.00
0.48
0.00
0.00
8.00
0.72
0.00
0.00
10.00
1.09
0.02
0.41
12.00
3.98
1.44
32.65
14.00
4.92
2.14
3.62
16.00
5.28
2.42
2.15
18.00
5.53
2.61
1.62
20.00
5.71
2.76
1.20
22.00
5.86
2.88
1.07
24.00
6.00
2.99
0.99
26.00
6.00
2.99
0.00
28.00
6.00
2.99
0.00
30.00
6.00
2.99
0.00
32.00
6.00
2.99
0.00
34.00
6.00
2.99
0.00
36.00
6.00
2.99
0.00
38.00
6.00
2.99
0.00
40.00
6.00
2.99
0.00
42.00
6.00
2.99
0.00
44.00
6.00
2.99
0.00
46.00
6.00
2.99
0.00
48.00
6.00
2.99
0.00
50.00
6.00
2.99
0.00
52.00
6.00
2.99
0.00
54.00
6.00
2.99
0.00
56.00
6.00
2.99
0.00
58.00
6.00
2.99
0.00
60.00
6.00
2.99
0.00
62.00
6.00
2.99
0.00
64.00
6.00
2.99
0.00
66.00
6.00
2.99
0.00
68.00
6.00
2.99
0.00
70.00
6.00
2.99
0.00
72.00
6.00
2.99
0.00
74.00
6.00
2.99
0.00
76.00
6.00
2.99
0.00
78.00
6.00
2.99
0.00
80.00
6.00
2.99
0.00
82.00
6.00
2.99
0.00
84.00
6.00
2.99
0.00
86.00
6.00
2.99
0.00
88.00
6.00
2.99
0.00
90.00
6.00
2.99
0.00
92.00
6.00
2.99
0.00
94.00
6.00
2.99
0.00
96.00
6.00
2.99
0.00
98.00
6.00
2.99
0.00
100.00
6.00
2.99
0.00
102.00
6.00
2.99
0.00
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
104.00
6.00
2.99
0.00
106.00
6.00
2.99
0.00
108.00
6.00
2.99
0.00
110.00
6.00
2.99
0.00
112.00
6.00
2.99
0.00
114.00
6.00
2.99
0.00
116.00
6.00
2.99
0.00
118.00
6.00
2.99
0.00
120.00
6.00
2.99
0.00
122.00
6.00
2.99
0.00
124.00
6.00
2.99
0.00
126.00
6.00
2.99
0.00
128.00
6.00
2.99
0.00
130.00
6.00
2.99
0.00
132.00
6.00
2.99
0.00
134.00
6.00
2.99
0.00
136.00
6.00
2.99
0.00
138.00
6.00
2.99
0.00
140.00
6.00
2.99
0.00
142.00
6.00
2.99
0.00
144.00
6.00
2.99
0.00
146.00
6.00
2.99
0.00
148.00
6.00
2.99
0.00
150.00
6.00
2.99
0.00
152.00
6.00
2.99
0.00
154.00
6.00
2.99
0.00
156.00
6.00
2.99
0.00
158.00
6.00
2.99
0.00
160.00
6.00
2.99
0.00
162.00
6.00
2.99
0.00
164.00
6.00
2.99
0.00
166.00
6.00
2.99
0.00
168.00
6.00
2.99
0.00
170.00
6.00
2.99
0.00
172.00
6.00
2.99
0.00
174.00
6.00
2.99
0.00
176.00
6.00
2.99
0.00
178.00
6.00
2.99
0.00
180.00
6.00
2.99
0.00
182.00
6.00
2.99
0.00
184.00
6.00
2.99
0.00
186.00
6.00
2.99
0.00
188.00
6.00
2.99
0.00
190.00
6.00
2.99
0.00
192.00
6.00
2.99
0.00
194.00
6.00
2.99
0.00
196.00
6.00
2.99
0.00
198.00
6.00
2.99
0.00
200.00
6.00
2.99
0.00

2020.17-BMP1 REVISED Type/1 24-hr 25-yr Concord Rainfall=6.00"
Prepared by {enter your company name here} Page 24
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/4/2022
Subcatchment 2S: (Post Developed)
Runoff = 122.16 cfs @ 11.96 hrs, Volume= 5.628 af, Depth= 3.78"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Type II 24-hr 25-yr Concord Rainfall=6.00"
Area (ac) CN
Description
10.770 83
RM-2 (C)
7.090 75
RM-2 (B)
17.860 80
Weighted Average
17.860
Pervious Area
Tc Length
Slope Velocity Capacity Description
(min) (feet)
(ft/ft) (ft/sec) (cfs)
5.0
Direct Entry,

2020.17-BMP1 REVISED
Type // 24-hr 25-yr Concord Rainfall=6.00"
Prepared by {enter your company name here} Page 25
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/4/2022
Hydrograph for Subcatchment 2S: (Post Developed)
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
0.00
0.00
0.00
0.00
2.00
0.13
0.00
0.00
4.00
0.29
0.00
0.00
6.00
0.48
0.00
0.00
8.00
0.72
0.02
0.35
10.00
1.09
0.11
1.41
12.00
3.98
2.02
103.64
14.00
4.92
2.82
3.62
16.00
5.28
3.14
2.24
18.00
5.53
3.36
1.75
20.00
5.71
3.52
1.28
22.00
5.86
3.66
1.17
24.00
6.00
3.78
1.08
26.00
6.00
3.78
0.00
28.00
6.00
3.78
0.00
30.00
6.00
3.78
0.00
32.00
6.00
3.78
0.00
34.00
6.00
3.78
0.00
36.00
6.00
3.78
0.00
38.00
6.00
3.78
0.00
40.00
6.00
3.78
0.00
42.00
6.00
3.78
0.00
44.00
6.00
3.78
0.00
46.00
6.00
3.78
0.00
48.00
6.00
3.78
0.00
50.00
6.00
3.78
0.00
52.00
6.00
3.78
0.00
54.00
6.00
3.78
0.00
56.00
6.00
3.78
0.00
58.00
6.00
3.78
0.00
60.00
6.00
3.78
0.00
62.00
6.00
3.78
0.00
64.00
6.00
3.78
0.00
66.00
6.00
3.78
0.00
68.00
6.00
3.78
0.00
70.00
6.00
3.78
0.00
72.00
6.00
3.78
0.00
74.00
6.00
3.78
0.00
76.00
6.00
3.78
0.00
78.00
6.00
3.78
0.00
80.00
6.00
3.78
0.00
82.00
6.00
3.78
0.00
84.00
6.00
3.78
0.00
86.00
6.00
3.78
0.00
88.00
6.00
3.78
0.00
90.00
6.00
3.78
0.00
92.00
6.00
3.78
0.00
94.00
6.00
3.78
0.00
96.00
6.00
3.78
0.00
98.00
6.00
3.78
0.00
100.00
6.00
3.78
0.00
102.00
6.00
3.78
0.00
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
104.00
6.00
3.78
0.00
106.00
6.00
3.78
0.00
108.00
6.00
3.78
0.00
110.00
6.00
3.78
0.00
112.00
6.00
3.78
0.00
114.00
6.00
3.78
0.00
116.00
6.00
3.78
0.00
118.00
6.00
3.78
0.00
120.00
6.00
3.78
0.00
122.00
6.00
3.78
0.00
124.00
6.00
3.78
0.00
126.00
6.00
3.78
0.00
128.00
6.00
3.78
0.00
130.00
6.00
3.78
0.00
132.00
6.00
3.78
0.00
134.00
6.00
3.78
0.00
136.00
6.00
3.78
0.00
138.00
6.00
3.78
0.00
140.00
6.00
3.78
0.00
142.00
6.00
3.78
0.00
144.00
6.00
3.78
0.00
146.00
6.00
3.78
0.00
148.00
6.00
3.78
0.00
150.00
6.00
3.78
0.00
152.00
6.00
3.78
0.00
154.00
6.00
3.78
0.00
156.00
6.00
3.78
0.00
158.00
6.00
3.78
0.00
160.00
6.00
3.78
0.00
162.00
6.00
3.78
0.00
164.00
6.00
3.78
0.00
166.00
6.00
3.78
0.00
168.00
6.00
3.78
0.00
170.00
6.00
3.78
0.00
172.00
6.00
3.78
0.00
174.00
6.00
3.78
0.00
176.00
6.00
3.78
0.00
178.00
6.00
3.78
0.00
180.00
6.00
3.78
0.00
182.00
6.00
3.78
0.00
184.00
6.00
3.78
0.00
186.00
6.00
3.78
0.00
188.00
6.00
3.78
0.00
190.00
6.00
3.78
0.00
192.00
6.00
3.78
0.00
194.00
6.00
3.78
0.00
196.00
6.00
3.78
0.00
198.00
6.00
3.78
0.00
200.00
6.00
3.78
0.00

2020.17-BMP1 REVISED
Type/1 24-hr 25-yr Concord Rainfall=6.00"
Prepared by {enter your company name here} Page 26
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/4/2022
Pond 3P: (BMP1)
Inflow Area = 17.860 ac, Inflow Depth = 3.78" for 25-yr Concord event
Inflow =
122.16 cfs @
11.96 hrs,
Volume=
5.628 of
Outflow =
29.31 cfs @
12.09 hrs,
Volume=
5.626 af, Atten= 76%, Lag= 7.8 min
Primary =
29.31 cfs @
12.09 hrs,
Volume=
5.626 of
Secondary =
0.00 cfs @
0.00 hrs,
Volume=
0.000 of
Routing by Stor-Ind method, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Peak Elev= 614.88' @ 12.09 hrs Surf.Area= 25,547 sf Storage= 120,391 cf
Plug -Flow detention time= 733.6 min calculated for 5.626 of (100% of inflow)
Center -of -Mass det. time= 733.9 min ( 1,544.0 - 810.1 )
Volume Invert
Avail.Storage Storage Description
#1 609.00'
150,165 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area
Inc.Store Cum.Store
(feet)
(sq-ft)
(cubic -feet) (cubic -feet)
609.00
15,725
0 0
610.00
17,253
16,489 16,489
612.00
20,478
37,731 54,220
614.00
23,930
44,408 98,628
616.00
27,607
51,537 150,165
Device Routing
Invert
Outlet Devices
#1 Primary
606.40'
24.0" x 60.0' long Culvert RCP, square edge headwall, Ke= 0.500
Outlet Invert= 606.00' S= 0.0067 7' Cc= 0.900 n= 0.013
#2 Device 1
609.00'
Exfiltration
Head (feet) 0.00 1.00 2.00 3.00 4.00 5.00 6.00
Disch. (cfs) 0.000 0.178 0.249 0.321 0.392 0.463 0.534
#3 Device 1
611.00'
6.0" Vert. Orifice/Grate C= 0.600
#4 Device 1
614.00'
2.00' x 3.00' Horiz. Top of Riser Limited to weir flow C= 0.600
#5 Secondary
615.00'
10.0' long x 16.0' breadth Spillway
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Coef. (English) 2.68 2.70 2.70 2.64 2.63 2.64 2.64 2.63
Primary OutFlow Max=29.30 cfs @ 12.09 hrs HW=614.88' (Free Discharge)
L1=Culvert (Passes 29.30 cfs of 41.37 cfs potential flow)
2=Exfltration (Custom Controls 0.53 cfs)
3=Orifice/Grate (Orifice Controls 1.80 cfs @ 9.17 fps)
=Top of Riser (Weir Controls 26.97 cfs @ 3.07 fps)
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=609.00' (Free Discharge)
5=Spillway ( Controls 0.00 cfs)

2020.17-BMP1 REVISED
Type // 24-hr 25-yr Concord Rainfall=6.00"
Prepared by {enter your company name here} Page 27
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/4/2022
Hydrograph for Pond 3P: (BMP1)
Time
Inflow
Storage
Elevation
Outflow
Primary
Secondary
(hours)
(cfs)
(cubic -feet)
(feet)
(cfs)
(cfs)
(cfs)
0.00
0.00
0
609.00
0.00
0.00
0.00
5.00
0.00
0
609.00
0.00
0.00
0.00
10.00
1.41
6,531
609.41
0.07
0.07
0.00
15.00
2.89
101,119
614.10
3.18
3.18
0.00
20.00
1.28
94,843
613.84
1.97
1.97
0.00
25.00
0.00
78,438
613.13
1.70
1.70
0.00
30.00
0.00
53,128
611.95
1.11
1.11
0.00
35.00
0.00
39,252
611.25
0.43
0.43
0.00
40.00
0.00
33,868
610.96
0.25
0.25
0.00
45.00
0.00
29,580
610.73
0.23
0.23
0.00
50.00
0.00
25,580
610.51
0.21
0.21
0.00
55.00
0.00
21,853
610.31
0.20
0.20
0.00
60.00
0.00
18,384
610.11
0.19
0.19
0.00
65.00
0.00
15,192
609.92
0.16
0.16
0.00
70.00
0.00
12,491
609.77
0.14
0.14
0.00
75.00
0.00
10,257
609.63
0.11
0.11
0.00
80.00
0.00
8,413
609.52
0.09
0.09
0.00
85.00
0.00
6,894
609.43
0.08
0.08
0.00
90.00
0.00
5,644
609.35
0.06
0.06
0.00
95.00
0.00
4,618
609.29
0.05
0.05
0.00
100.00
0.00
3,777
609.24
0.04
0.04
0.00
105.00
0.00
3,087
609.19
0.03
0.03
0.00
110.00
0.00
2,523
609.16
0.03
0.03
0.00
115.00
0.00
2,061
609.13
0.02
0.02
0.00
120.00
0.00
1,683
609.11
0.02
0.02
0.00
125.00
0.00
1,374
609.09
0.02
0.02
0.00
130.00
0.00
1,122
609.07
0.01
0.01
0.00
135.00
0.00
916
609.06
0.01
0.01
0.00
140.00
0.00
747
609.05
0.01
0.01
0.00
145.00
0.00
610
609.04
0.01
0.01
0.00
150.00
0.00
498
609.03
0.01
0.01
0.00
155.00
0.00
406
609.03
0.00
0.00
0.00
160.00
0.00
332
609.02
0.00
0.00
0.00
165.00
0.00
271
609.02
0.00
0.00
0.00
170.00
0.00
221
609.01
0.00
0.00
0.00
175.00
0.00
180
609.01
0.00
0.00
0.00
180.00
0.00
147
609.01
0.00
0.00
0.00
185.00
0.00
120
609.01
0.00
0.00
0.00
190.00
0.00
98
609.01
0.00
0.00
0.00
195.00
0.00
80
609.01
0.00
0.00
0.00
200.00
0.00
65
609.00
0.00
0.00
0.00

2020.17-BMP1 REVISED
Type // 24-hr 25-yr Concord Rainfall=6.00"
Prepared by {enter your company name here} Page 28
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/4/2022
Stage -Discharge for Pond 3P: (BMP1)
Elevation Discharge Primary Secondary
(feet)
(cfs)
(cfs)
(cfs)
609.00
0.00
0.00
0.00
609.10
0.02
0.02
0.00
609.20
0.04
0.04
0.00
609.30
0.05
0.05
0.00
609.40
0.07
0.07
0.00
609.50
0.09
0.09
0.00
609.60
0.11
0.11
0.00
609.70
0.12
0.12
0.00
609.80
0.14
0.14
0.00
609.90
0.16
0.16
0.00
610.00
0.18
0.18
0.00
610.10
0.19
0.19
0.00
610.20
0.19
0.19
0.00
610.30
0.20
0.20
0.00
610.40
0.21
0.21
0.00
610.50
0.21
0.21
0.00
610.60
0.22
0.22
0.00
610.70
0.23
0.23
0.00
610.80
0.23
0.23
0.00
610.90
0.24
0.24
0.00
611.00
0.25
0.25
0.00
611.10
0.29
0.29
0.00
611.20
0.38
0.38
0.00
611.30
0.50
0.50
0.00
611.40
0.64
0.64
0.00
611.50
0.76
0.76
0.00
611.60
0.85
0.85
0.00
611.70
0.93
0.93
0.00
611.80
1.01
1.01
0.00
611.90
1.08
1.08
0.00
612.00
1.14
1.14
0.00
612.10
1.20
1.20
0.00
612.20
1.26
1.26
0.00
612.30
1.31
1.31
0.00
612.40
1.36
1.36
0.00
612.50
1.41
1.41
0.00
612.60
1.46
1.46
0.00
612.70
1.51
1.51
0.00
612.80
1.55
1.55
0.00
612.90
1.60
1.60
0.00
613.00
1.64
1.64
0.00
613.10
1.69
1.69
0.00
613.20
1.73
1.73
0.00
613.30
1.77
1.77
0.00
613.40
1.81
1.81
0.00
613.50
1.85
1.85
0.00
613.60
1.88
1.88
0.00
613.70
1.92
1.92
0.00
613.80
1.96
1.96
0.00
613.90
1.99
1.99
0.00
614.00
2.03
2.03
0.00
614.10
3.10
3.10
0.00
Elevation Discharge Primary Secondary
(feet)
(cfs)
(cfs)
(cfs)
614.20
5.03
5.03
0.00
614.30
7.51
7.51
0.00
614.40
10.44
10.44
0.00
614.50
13.76
13.76
0.00
614.60
17.43
17.43
0.00
614.70
21.42
21.42
0.00
614.80
25.70
25.70
0.00
614.90
29.74
29.74
0.00
615.00
31.25
31.25
0.00
615.10
33.54
32.69
0.85
615.20
36.46
34.06
2.40
615.30
39.80
35.38
4.42
615.40
43.47
36.64
6.83
615.50
47.41
37.87
9.55
615.60
51.60
39.05
12.55
615.70
55.83
40.20
15.64
615.80
60.20
41.31
18.89
615.90
64.89
42.39
22.50
616.00
69.75
43.45
26.30

2020.17-BMP1 REVISED
Type // 24-hr 25-yr Concord Rainfall=6.00"
Prepared by {enter your company name here} Page 29
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/4/2022
Stage -Area -Storage for Pond 3P: (BMP1)
Elevation
Surface
Storage
(feet)
(sq-ft)
(cubic -feet)
609.00
15,725
0
609.10
15,878
1,580
609.20
16,031
3,176
609.30
16,183
4,786
609.40
16,336
6,412
609.50
16,489
8,054
609.60
16,642
9,710
609.70
16,795
11,382
609.80
16,947
13,069
609.90
17,100
14,771
610.00
17,253
16,489
610.10
17,414
18,222
610.20
17,576
19,972
610.30
17,737
21,737
610.40
17,898
23,519
610.50
18,059
25,317
610.60
18,221
27,131
610.70
18,382
28,961
610.80
18,543
30,807
610.90
18,704
32,670
611.00
18,866
34,548
611.10
19,027
36,443
611.20
19,188
38,354
611.30
19,349
40,280
611.40
19,510
42,223
611.50
19,672
44,183
611.60
19,833
46,158
611.70
19,994
48,149
611.80
20,155
50,157
611.90
20,317
52,180
612.00
20,478
54,220
612.10
20,651
56,276
612.20
20,823
58,350
612.30
20,996
60,441
612.40
21,168
62,549
612.50
21,341
64,675
612.60
21,514
66,817
612.70
21,686
68,977
612.80
21,859
71,155
612.90
22,031
73,349
613.00
22,204
75,561
613.10
22,377
77,790
613.20
22,549
80,036
613.30
22,722
82,300
613.40
22,894
84,581
613.50
23,067
86,879
613.60
23,240
89,194
613.70
23,412
91,527
613.80
23,585
93,877
613.90
23,757
96,244
614.00
23,930
98,628
614.10
24,114
101,030
Elevation
Surface
Storage
(feet)
(sq-ft)
(cubic -feet)
614.20
24,298
103,451
614.30
24,482
105,890
614.40
24,665
108,347
614.50
24,849
110,823
614.60
25,033
113,317
614.70
25,217
115,829
614.80
25,401
118,360
614.90
25,585
120,910
615.00
25,769
123,477
615.10
25,952
126,063
615.20
26,136
128,668
615.30
26,320
131,291
615.40
26,504
133,932
615.50
26,688
136,591
615.60
26,872
139,269
615.70
27,055
141,966
615.80
27,239
144,680
615.90
27,423
147,413
616.00
27,607
150,165

2020.17-BMP1 REVISED Type 11 24-hr 50-yr Concord Rainfall=6.80"
Prepared by {enter your company name here} Page 30
HvdroCAD® 8.00 s/n 004317 © 2006 HvdroCAD Software Solutions LLC 6/4/2022
Time span=0.00-200.00 hrs, dt=0.01 hrs, 20001 points
Runoff by SCS TR-20 method, UH=SCS
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment 1S: (Predeveloped) Runoff Area=17.860 ac Runoff Depth=3.66"
Flow Length=1,107' Tc=22.5 min CN=72 Runoff=67.84 cfs 5.446 of
Subcatchment 2S: (Post Developed) Runoff Area=17.860 ac Runoff Depth=4.51"
Tc=5.0 min CN=80 Runoff=144.39 cfs 6.713 of
Pond 3P: (BMP1) Peak Elev=615.54' Storage=137,626 cf Inflow=144.39 cfs 6.713 of
Primary=38.33 cfs 6.581 of Secondary=10.69 cfs 0.131 of Outflow=49.02 cfs 6.711 of
Total Runoff Area = 35.720 ac Runoff Volume = 12.159 of Average Runoff Depth = 4.08"
100.00% Pervious Area = 35.720 ac 0.00% Impervious Area = 0.000 ac

2020.17-BMP1 REVISED
Type 11 24-hr 50-yr Concord Rainfall=6.80"
Prepared by {enter your company name here} Page 31
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/4/2022
Subcatchment 1S: (Predeveloped)
BASED ON EXISTING CONDITIONS
Runoff = 67.84 cfs @ 12.15 hrs, Volume= 5.446 af, Depth= 3.66"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Type II 24-hr 50-yr Concord Rainfall=6.80"
Area (ac)
CN
Description
3.200
73
Woods, Fair, HSG C
3.600
60
Woods, Fair, HSG B
3.500
69
Pasture/grassland/range, Fair, HSG B
7.560
79
Pasture/grassland/range, Fair, HSG C
17.860
72
Weighted Average
17.860
Pervious Area
Tc
Length
Slope
Velocity
Capacity Description
(min)
(feet)
(ft/ft)
(ft/sec)
(cfs)
10.7
100
0.0371
0.16
Sheet Flow,
Grass: Dense n= 0.240 P2= 3.50"
6.6
719
0.0672
1.81
Shallow Concentrated Flow,
Short Grass Pasture Kv= 7.0 fps
5.2
288
0.0347
0.93
Shallow Concentrated Flow,
Woodland Kv= 5.0 fps
22.5 1,107 Total

2020.17-BMP1 REVISED
Type // 24-hr 50-yr Concord Rainfall=6.80"
Prepared by {enter your company name here} Page 32
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/4/2022
Hydrograph for Subcatchment 1S: (Predeveloped)
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
0.00
0.00
0.00
0.00
2.00
0.15
0.00
0.00
4.00
0.33
0.00
0.00
6.00
0.54
0.00
0.00
8.00
0.82
0.00
0.00
10.00
1.23
0.05
0.70
12.00
4.51
1.83
40.89
14.00
5.58
2.65
4.29
16.00
5.98
2.98
2.54
18.00
6.26
3.21
1.91
20.00
6.47
3.38
1.42
22.00
6.64
3.53
1.25
24.00
6.80
3.66
1.16
26.00
6.80
3.66
0.00
28.00
6.80
3.66
0.00
30.00
6.80
3.66
0.00
32.00
6.80
3.66
0.00
34.00
6.80
3.66
0.00
36.00
6.80
3.66
0.00
38.00
6.80
3.66
0.00
40.00
6.80
3.66
0.00
42.00
6.80
3.66
0.00
44.00
6.80
3.66
0.00
46.00
6.80
3.66
0.00
48.00
6.80
3.66
0.00
50.00
6.80
3.66
0.00
52.00
6.80
3.66
0.00
54.00
6.80
3.66
0.00
56.00
6.80
3.66
0.00
58.00
6.80
3.66
0.00
60.00
6.80
3.66
0.00
62.00
6.80
3.66
0.00
64.00
6.80
3.66
0.00
66.00
6.80
3.66
0.00
68.00
6.80
3.66
0.00
70.00
6.80
3.66
0.00
72.00
6.80
3.66
0.00
74.00
6.80
3.66
0.00
76.00
6.80
3.66
0.00
78.00
6.80
3.66
0.00
80.00
6.80
3.66
0.00
82.00
6.80
3.66
0.00
84.00
6.80
3.66
0.00
86.00
6.80
3.66
0.00
88.00
6.80
3.66
0.00
90.00
6.80
3.66
0.00
92.00
6.80
3.66
0.00
94.00
6.80
3.66
0.00
96.00
6.80
3.66
0.00
98.00
6.80
3.66
0.00
100.00
6.80
3.66
0.00
102.00
6.80
3.66
0.00
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
104.00
6.80
3.66
0.00
106.00
6.80
3.66
0.00
108.00
6.80
3.66
0.00
110.00
6.80
3.66
0.00
112.00
6.80
3.66
0.00
114.00
6.80
3.66
0.00
116.00
6.80
3.66
0.00
118.00
6.80
3.66
0.00
120.00
6.80
3.66
0.00
122.00
6.80
3.66
0.00
124.00
6.80
3.66
0.00
126.00
6.80
3.66
0.00
128.00
6.80
3.66
0.00
130.00
6.80
3.66
0.00
132.00
6.80
3.66
0.00
134.00
6.80
3.66
0.00
136.00
6.80
3.66
0.00
138.00
6.80
3.66
0.00
140.00
6.80
3.66
0.00
142.00
6.80
3.66
0.00
144.00
6.80
3.66
0.00
146.00
6.80
3.66
0.00
148.00
6.80
3.66
0.00
150.00
6.80
3.66
0.00
152.00
6.80
3.66
0.00
154.00
6.80
3.66
0.00
156.00
6.80
3.66
0.00
158.00
6.80
3.66
0.00
160.00
6.80
3.66
0.00
162.00
6.80
3.66
0.00
164.00
6.80
3.66
0.00
166.00
6.80
3.66
0.00
168.00
6.80
3.66
0.00
170.00
6.80
3.66
0.00
172.00
6.80
3.66
0.00
174.00
6.80
3.66
0.00
176.00
6.80
3.66
0.00
178.00
6.80
3.66
0.00
180.00
6.80
3.66
0.00
182.00
6.80
3.66
0.00
184.00
6.80
3.66
0.00
186.00
6.80
3.66
0.00
188.00
6.80
3.66
0.00
190.00
6.80
3.66
0.00
192.00
6.80
3.66
0.00
194.00
6.80
3.66
0.00
196.00
6.80
3.66
0.00
198.00
6.80
3.66
0.00
200.00
6.80
3.66
0.00

2020.17-BMP1 REVISED Type 11 24-hr 50-yr Concord Rainfall=6.80"
Prepared by {enter your company name here} Page 33
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/4/2022
Subcatchment 2S: (Post Developed)
Runoff = 144.39 cfs @ 11.96 hrs, Volume= 6.713 af, Depth= 4.51"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Type II 24-hr 50-yr Concord Rainfall=6.80"
Area (ac) CN
Description
10.770 83
RM-2 (C)
7.090 75
RM-2 (B)
17.860 80
Weighted Average
17.860
Pervious Area
Tc Length
Slope Velocity Capacity Description
(min) (feet)
(ft/ft) (ft/sec) (cfs)
5.0
Direct Entry,

2020.17-BMP1 REVISED
Type // 24-hr 50-yr Concord Rainfall=6.80"
Prepared by {enter your company name here} Page 34
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/4/2022
Hydrograph for Subcatchment 2S: (Post Developed)
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
0.00
0.00
0.00
0.00
2.00
0.15
0.00
0.00
4.00
0.33
0.00
0.00
6.00
0.54
0.00
0.06
8.00
0.82
0.04
0.55
10.00
1.23
0.17
1.87
12.00
4.51
2.47
122.03
14.00
5.58
3.40
4.20
16.00
5.98
3.77
2.60
18.00
6.26
4.02
2.02
20.00
6.47
4.21
1.47
22.00
6.64
4.37
1.35
24.00
6.80
4.51
1.24
26.00
6.80
4.51
0.00
28.00
6.80
4.51
0.00
30.00
6.80
4.51
0.00
32.00
6.80
4.51
0.00
34.00
6.80
4.51
0.00
36.00
6.80
4.51
0.00
38.00
6.80
4.51
0.00
40.00
6.80
4.51
0.00
42.00
6.80
4.51
0.00
44.00
6.80
4.51
0.00
46.00
6.80
4.51
0.00
48.00
6.80
4.51
0.00
50.00
6.80
4.51
0.00
52.00
6.80
4.51
0.00
54.00
6.80
4.51
0.00
56.00
6.80
4.51
0.00
58.00
6.80
4.51
0.00
60.00
6.80
4.51
0.00
62.00
6.80
4.51
0.00
64.00
6.80
4.51
0.00
66.00
6.80
4.51
0.00
68.00
6.80
4.51
0.00
70.00
6.80
4.51
0.00
72.00
6.80
4.51
0.00
74.00
6.80
4.51
0.00
76.00
6.80
4.51
0.00
78.00
6.80
4.51
0.00
80.00
6.80
4.51
0.00
82.00
6.80
4.51
0.00
84.00
6.80
4.51
0.00
86.00
6.80
4.51
0.00
88.00
6.80
4.51
0.00
90.00
6.80
4.51
0.00
92.00
6.80
4.51
0.00
94.00
6.80
4.51
0.00
96.00
6.80
4.51
0.00
98.00
6.80
4.51
0.00
100.00
6.80
4.51
0.00
102.00
6.80
4.51
0.00
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
104.00
6.80
4.51
0.00
106.00
6.80
4.51
0.00
108.00
6.80
4.51
0.00
110.00
6.80
4.51
0.00
112.00
6.80
4.51
0.00
114.00
6.80
4.51
0.00
116.00
6.80
4.51
0.00
118.00
6.80
4.51
0.00
120.00
6.80
4.51
0.00
122.00
6.80
4.51
0.00
124.00
6.80
4.51
0.00
126.00
6.80
4.51
0.00
128.00
6.80
4.51
0.00
130.00
6.80
4.51
0.00
132.00
6.80
4.51
0.00
134.00
6.80
4.51
0.00
136.00
6.80
4.51
0.00
138.00
6.80
4.51
0.00
140.00
6.80
4.51
0.00
142.00
6.80
4.51
0.00
144.00
6.80
4.51
0.00
146.00
6.80
4.51
0.00
148.00
6.80
4.51
0.00
150.00
6.80
4.51
0.00
152.00
6.80
4.51
0.00
154.00
6.80
4.51
0.00
156.00
6.80
4.51
0.00
158.00
6.80
4.51
0.00
160.00
6.80
4.51
0.00
162.00
6.80
4.51
0.00
164.00
6.80
4.51
0.00
166.00
6.80
4.51
0.00
168.00
6.80
4.51
0.00
170.00
6.80
4.51
0.00
172.00
6.80
4.51
0.00
174.00
6.80
4.51
0.00
176.00
6.80
4.51
0.00
178.00
6.80
4.51
0.00
180.00
6.80
4.51
0.00
182.00
6.80
4.51
0.00
184.00
6.80
4.51
0.00
186.00
6.80
4.51
0.00
188.00
6.80
4.51
0.00
190.00
6.80
4.51
0.00
192.00
6.80
4.51
0.00
194.00
6.80
4.51
0.00
196.00
6.80
4.51
0.00
198.00
6.80
4.51
0.00
200.00
6.80
4.51
0.00

2020.17-BMP1 REVISED
Type 11 24-hr 50-yr Concord Rainfall=6.80"
Prepared by {enter your company name here} Page 35
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/4/2022
Pond 3P: (BMP1)
Inflow Area = 17.860 ac, Inflow Depth = 4.51" for 50-yr Concord event
Inflow =
144.39 cfs @
11.96 hrs,
Volume=
6.713 of
Outflow =
49.02 cfs @
12.07 hrs,
Volume=
6.711 af, Atten= 66%, Lag= 6.4 min
Primary =
38.33 cfs @
12.07 hrs,
Volume=
6.581 of
Secondary =
10.69 cfs @
12.07 hrs,
Volume=
0.131 of
Routing by Stor-Ind method, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Peak Elev= 615.54' @ 12.07 hrs Surf.Area= 26,759 sf Storage= 137,626 cf
Plug -Flow detention time= 635.3 min calculated for 6.711 of (100% of inflow)
Center -of -Mass det. time= 635.2 min ( 1,440.3 - 805.1 )
Volume Invert
Avail.Storage Storage Description
#1 609.00'
150,165 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area
Inc.Store Cum.Store
(feet)
(sq-ft)
(cubic -feet) (cubic -feet)
609.00
15,725
0 0
610.00
17,253
16,489 16,489
612.00
20,478
37,731 54,220
614.00
23,930
44,408 98,628
616.00
27,607
51,537 150,165
Device Routing
Invert
Outlet Devices
#1 Primary
606.40'
24.0" x 60.0' long Culvert RCP, square edge headwall, Ke= 0.500
Outlet Invert= 606.00' S= 0.0067 7' Cc= 0.900 n= 0.013
#2 Device 1
609.00'
Exfiltration
Head (feet) 0.00 1.00 2.00 3.00 4.00 5.00 6.00
Disch. (cfs) 0.000 0.178 0.249 0.321 0.392 0.463 0.534
#3 Device 1
611.00'
6.0" Vert. Orifice/Grate C= 0.600
#4 Device 1
614.00'
2.00' x 3.00' Horiz. Top of Riser Limited to weir flow C= 0.600
#5 Secondary
615.00'
10.0' long x 16.0' breadth Spillway
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Coef. (English) 2.68 2.70 2.70 2.64 2.63 2.64 2.64 2.63
Primary OutFlow Max=38.31 cfs @ 12.07 hrs HW=615.54' (Free Discharge)
L1=Culvert (Passes 38.31 cfs of 43.15 cfs potential flow)
2=Exfltration (Custom Controls 0.53 cfs)
3=Orifice/Grate (Orifice Controls 1.96 cfs @ 9.97 fps)
=Top of Riser (Orifice Controls 35.82 cfs @ 5.97 fps)
Secondary OutFlow Max=10.64 cfs @ 12.07 hrs HW=615.54' (Free Discharge)
5=Spillway (Weir Controls 10.64 cfs @ 1.98 fps)

2020.17-BMP1 REVISED
Type // 24-hr 50-yr Concord Rainfall=6.80"
Prepared by {enter your company name here} Page 36
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/4/2022
Hydrograph for Pond 3P: (BMP1)
Time
Inflow
Storage
Elevation
Outflow
Primary
Secondary
(hours)
(cfs)
(cubic -feet)
(feet)
(cfs)
(cfs)
(cfs)
0.00
0.00
0
609.00
0.00
0.00
0.00
5.00
0.00
0
609.00
0.00
0.00
0.00
10.00
1.87
9,707
609.60
0.11
0.11
0.00
15.00
3.35
101,762
614.13
3.65
3.65
0.00
20.00
1.47
97,009
613.93
2.01
2.01
0.00
25.00
0.00
82,280
613.30
1.77
1.77
0.00
30.00
0.00
55,667
612.07
1.18
1.18
0.00
35.00
0.00
40,284
611.30
0.50
0.50
0.00
40.00
0.00
34,417
610.99
0.25
0.25
0.00
45.00
0.00
30,093
610.76
0.23
0.23
0.00
50.00
0.00
26,058
610.54
0.22
0.22
0.00
55.00
0.00
22,298
610.33
0.20
0.20
0.00
60.00
0.00
18,798
610.13
0.19
0.19
0.00
65.00
0.00
15,561
609.95
0.17
0.17
0.00
70.00
0.00
12,797
609.78
0.14
0.14
0.00
75.00
0.00
10,510
609.65
0.12
0.12
0.00
80.00
0.00
8,621
609.53
0.10
0.10
0.00
85.00
0.00
7,065
609.44
0.08
0.08
0.00
90.00
0.00
5,785
609.36
0.06
0.06
0.00
95.00
0.00
4,734
609.30
0.05
0.05
0.00
100.00
0.00
3,872
609.24
0.04
0.04
0.00
105.00
0.00
3,165
609.20
0.04
0.04
0.00
110.00
0.00
2,586
609.16
0.03
0.03
0.00
115.00
0.00
2,113
609.13
0.02
0.02
0.00
120.00
0.00
1,725
609.11
0.02
0.02
0.00
125.00
0.00
1,409
609.09
0.02
0.02
0.00
130.00
0.00
1,150
609.07
0.01
0.01
0.00
135.00
0.00
939
609.06
0.01
0.01
0.00
140.00
0.00
766
609.05
0.01
0.01
0.00
145.00
0.00
625
609.04
0.01
0.01
0.00
150.00
0.00
511
609.03
0.01
0.01
0.00
155.00
0.00
417
609.03
0.00
0.00
0.00
160.00
0.00
340
609.02
0.00
0.00
0.00
165.00
0.00
278
609.02
0.00
0.00
0.00
170.00
0.00
227
609.01
0.00
0.00
0.00
175.00
0.00
185
609.01
0.00
0.00
0.00
180.00
0.00
151
609.01
0.00
0.00
0.00
185.00
0.00
123
609.01
0.00
0.00
0.00
190.00
0.00
101
609.01
0.00
0.00
0.00
195.00
0.00
82
609.01
0.00
0.00
0.00
200.00
0.00
67
609.00
0.00
0.00
0.00

2020.17-BMP1 REVISED
Type // 24-hr 50-yr Concord Rainfall=6.80"
Prepared by {enter your company name here} Page 37
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/4/2022
Stage -Discharge for Pond 3P: (BMP1)
Elevation Discharge Primary Secondary
(feet)
(cfs)
(cfs)
(cfs)
609.00
0.00
0.00
0.00
609.10
0.02
0.02
0.00
609.20
0.04
0.04
0.00
609.30
0.05
0.05
0.00
609.40
0.07
0.07
0.00
609.50
0.09
0.09
0.00
609.60
0.11
0.11
0.00
609.70
0.12
0.12
0.00
609.80
0.14
0.14
0.00
609.90
0.16
0.16
0.00
610.00
0.18
0.18
0.00
610.10
0.19
0.19
0.00
610.20
0.19
0.19
0.00
610.30
0.20
0.20
0.00
610.40
0.21
0.21
0.00
610.50
0.21
0.21
0.00
610.60
0.22
0.22
0.00
610.70
0.23
0.23
0.00
610.80
0.23
0.23
0.00
610.90
0.24
0.24
0.00
611.00
0.25
0.25
0.00
611.10
0.29
0.29
0.00
611.20
0.38
0.38
0.00
611.30
0.50
0.50
0.00
611.40
0.64
0.64
0.00
611.50
0.76
0.76
0.00
611.60
0.85
0.85
0.00
611.70
0.93
0.93
0.00
611.80
1.01
1.01
0.00
611.90
1.08
1.08
0.00
612.00
1.14
1.14
0.00
612.10
1.20
1.20
0.00
612.20
1.26
1.26
0.00
612.30
1.31
1.31
0.00
612.40
1.36
1.36
0.00
612.50
1.41
1.41
0.00
612.60
1.46
1.46
0.00
612.70
1.51
1.51
0.00
612.80
1.55
1.55
0.00
612.90
1.60
1.60
0.00
613.00
1.64
1.64
0.00
613.10
1.69
1.69
0.00
613.20
1.73
1.73
0.00
613.30
1.77
1.77
0.00
613.40
1.81
1.81
0.00
613.50
1.85
1.85
0.00
613.60
1.88
1.88
0.00
613.70
1.92
1.92
0.00
613.80
1.96
1.96
0.00
613.90
1.99
1.99
0.00
614.00
2.03
2.03
0.00
614.10
3.10
3.10
0.00
Elevation Discharge Primary Secondary
(feet)
(cfs)
(cfs)
(cfs)
614.20
5.03
5.03
0.00
614.30
7.51
7.51
0.00
614.40
10.44
10.44
0.00
614.50
13.76
13.76
0.00
614.60
17.43
17.43
0.00
614.70
21.42
21.42
0.00
614.80
25.70
25.70
0.00
614.90
29.74
29.74
0.00
615.00
31.25
31.25
0.00
615.10
33.54
32.69
0.85
615.20
36.46
34.06
2.40
615.30
39.80
35.38
4.42
615.40
43.47
36.64
6.83
615.50
47.41
37.87
9.55
615.60
51.60
39.05
12.55
615.70
55.83
40.20
15.64
615.80
60.20
41.31
18.89
615.90
64.89
42.39
22.50
616.00
69.75
43.45
26.30

2020.17-BMP1 REVISED
Type // 24-hr 50-yr Concord Rainfall=6.80"
Prepared by {enter your company name here} Page 38
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/4/2022
Stage -Area -Storage for Pond 3P: (BMP1)
Elevation
Surface
Storage
(feet)
(sq-ft)
(cubic -feet)
609.00
15,725
0
609.10
15,878
1,580
609.20
16,031
3,176
609.30
16,183
4,786
609.40
16,336
6,412
609.50
16,489
8,054
609.60
16,642
9,710
609.70
16,795
11,382
609.80
16,947
13,069
609.90
17,100
14,771
610.00
17,253
16,489
610.10
17,414
18,222
610.20
17,576
19,972
610.30
17,737
21,737
610.40
17,898
23,519
610.50
18,059
25,317
610.60
18,221
27,131
610.70
18,382
28,961
610.80
18,543
30,807
610.90
18,704
32,670
611.00
18,866
34,548
611.10
19,027
36,443
611.20
19,188
38,354
611.30
19,349
40,280
611.40
19,510
42,223
611.50
19,672
44,183
611.60
19,833
46,158
611.70
19,994
48,149
611.80
20,155
50,157
611.90
20,317
52,180
612.00
20,478
54,220
612.10
20,651
56,276
612.20
20,823
58,350
612.30
20,996
60,441
612.40
21,168
62,549
612.50
21,341
64,675
612.60
21,514
66,817
612.70
21,686
68,977
612.80
21,859
71,155
612.90
22,031
73,349
613.00
22,204
75,561
613.10
22,377
77,790
613.20
22,549
80,036
613.30
22,722
82,300
613.40
22,894
84,581
613.50
23,067
86,879
613.60
23,240
89,194
613.70
23,412
91,527
613.80
23,585
93,877
613.90
23,757
96,244
614.00
23,930
98,628
614.10
24,114
101,030
Elevation
Surface
Storage
(feet)
(sq-ft)
(cubic -feet)
614.20
24,298
103,451
614.30
24,482
105,890
614.40
24,665
108,347
614.50
24,849
110,823
614.60
25,033
113,317
614.70
25,217
115,829
614.80
25,401
118,360
614.90
25,585
120,910
615.00
25,769
123,477
615.10
25,952
126,063
615.20
26,136
128,668
615.30
26,320
131,291
615.40
26,504
133,932
615.50
26,688
136,591
615.60
26,872
139,269
615.70
27,055
141,966
615.80
27,239
144,680
615.90
27,423
147,413
616.00
27,607
150,165

2020.17-BMP1 REVISED
Type 11 24-hr 50-yr Concord Rainfall=6.80"
Prepared by Latham -Walters Engineer, Inc. Page 39
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 1/19/2022
Primary Outflow Max=24.13 cfs @ 12.11 hrs HVV=615.19' (Free Discharge)
t—#Culvert (Inlet Controls 24.13 cfs @ 13.66 fps)
2=Exfiltration (Passes < 0.46 cfs potential flow)
3=Orifice/Grate (Passes < 1.88 cfs potential flow)
=Top of Riser (Passes < 42.78 cfs potential flow)
Secondary Outflow Max=2.27 cfs @ 12.11 hrs HW=615.19' (Free Discharge)
L5=Spillway (Weir Controls 2.27 cfs @ 1.18 fps)

2020.17-BMP1 REVISED Type 11 24-hr 50-yr Concord Rainfall=6.80"
Prepared by Latham -Walters Engineer, Inc. Page 40
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 1/19/2022
Hydrograph for Pond 3P: (BMP1)
Time
Inflow
Storage
Elevation
Outflow
Primary
Secondary
(hours)
(cfs)
(cubic -feet)
(feet)
(cfs)
(cfs)
(cfs)
0.00
0.00
0
609.00
0.00
0.00
0.00
5.00
0.00
0
609.00
0.00
0.00
0.00
10.00
1.70
8,888
609.55
0.08
0.08
0.00
15.00
3.05
78,574
613.13
3.31
3.31
0.00
20.00
1.34
75,321
612.99
1.58
1.58
0.00
25.00
0.00
65,957
612.56
1.39
1.39
0.00
30.00
0.00
46,098
611.60
0.80
0.80
0.00
35.00
0.00
37,148
611.14
0.28
0.28
0.00
40.00
0.00
33,062
610.92
0.21
0.21
0.00
45.00
0.00
29,423
610.73
0.20
0.20
0.00
50.00
0.00
25,995
610.54
0.18
0.18
0.00
55.00
0.00
22,768
610.36
0.17
0.17
0.00
60.00
0.00
19,734
610.19
0.16
0.16
0.00
65.00
0.00
16,884
610.02
0.15
0.15
0.00
70.00
0.00
14,299
609.87
0.13
0.13
0.00
75.00
0.00
12,094
609.74
0.11
0.11
0.00
80.00
0.00
10,220
609.63
0.10
0.10
0.00
85.00
0.00
8,629
609.53
0.08
0.08
0.00
90.00
0.00
7,281
609.45
0.07
0.07
0.00
95.00
0.00
6,140
609.38
0.06
0.06
0.00
100.00
0.00
5,174
609.32
0.05
0.05
0.00
105.00
0.00
4,359
609.27
0.04
0.04
0.00
110.00
0.00
33671
609.23
0.04
0.04
0.00
115.00
0.00
33090
609.19
0.03
0.03
0.00
120.00
0.00
23601
609.16
0.02
0.02
0.00
125.00
0.00
23188
609.14
0.02
0.02
0.00
130.00
0.00
13841
609.12
0.02
0.02
0.00
135.00
0.00
13549
609.10
0.01
0.01
0.00
140.00
0.00
13302
609.08
0.01
0.01
0.00
145.00
0.00
13095
609.07
0.01
0.01
0.00
150.00
0.00
921
609.06
0.01
0.01
0.00
155.00
0.00
774
609.05
0.01
0.01
0.00
160.00
0.00
651
609.04
0.01
0.01
0.00
165.00
0.00
547
609.03
0.01
0.01
0.00
170.00
0.00
460
609.03
0.00
0.00
0.00
175.00
0.00
387
609.02
0.00
0.00
0.00
180.00
0.00
325
609.02
0.00
0.00
0.00
185.00
0.00
274
609.02
0.00
0.00
0.00
190.00
0.00
230
609.01
0.00
0.00
0.00
195.00
0.00
194
609.01
0.00
0.00
0.00
200.00
0.00
163
609.01
0.00
0.00
0.00

2020.17-BMP1 REVISED Type 11 24-hr 50-yr Concord Rainfall=6.80"
Prepared by Latham -Walters Engineer, Inc. Page 41
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 1/19/2022
Stage -Discharge for Pond 3P: (BMP1)
Elevation Discharge Primary Secondary
(feet)
(cfs)
(cfs)
(cfs)
609.00
0.00
0.00
0.00
609.10
0.02
0.02
0.00
609.20
0.03
0.03
0.00
609.30
0.05
0.05
0.00
609.40
0.06
0.06
0.00
609.50
0.08
0.08
0.00
609.60
0.09
0.09
0.00
609.70
0.11
0.11
0.00
609.80
0.12
0.12
0.00
609.90
0.14
0.14
0.00
610.00
0.15
0.15
0.00
610.10
0.16
0.16
0.00
610.20
0.16
0.16
0.00
610.30
0.17
0.17
0.00
610.40
0.18
0.18
0.00
610.50
0.18
0.18
0.00
610.60
0.19
0.19
0.00
610.70
0.19
0.19
0.00
610.80
0.20
0.20
0.00
610.90
0.21
0.21
0.00
611.00
0.21
0.21
0.00
611.10
0.25
0.25
0.00
611.20
0.34
0.34
0.00
611.30
0.46
0.46
0.00
611.40
0.60
0.60
0.00
611.50
0.72
0.72
0.00
611.60
0.81
0.81
0.00
611.70
0.89
0.89
0.00
611.80
0.96
0.96
0.00
611.90
1.03
1.03
0.00
612.00
1.09
1.09
0.00
612.10
1.15
1.15
0.00
612.20
1.21
1.21
0.00
612.30
1.26
1.26
0.00
612.40
1.31
1.31
0.00
612.50
1.36
1.36
0.00
612.60
1.41
1.41
0.00
612.70
1.45
1.45
0.00
612.80
1.50
1.50
0.00
612.90
1.54
1.54
0.00
613.00
1.58
1.58
0.00
613.10
2.66
2.66
0.00
613.20
4.59
4.59
0.00
Elevation Discharge Primary Secondary
(feet)
(cfs)
(cfs)
(cfs)
613.30
7.08
7.08
0.00
613.40
10.02
10.02
0.00
613.50
13.34
13.34
0.00
613.60
17.02
17.02
0.00
613.70
21.01
21.01
0.00
613.80
21.94
21.94
0.00
613.90
22.11
22.11
0.00
614.00
22.27
22.27
0.00
614.10
22.43
22.43
0.00
614.20
22.59
22.59
0.00
614.30
22.75
22.75
0.00
614.40
22.91
22.91
0.00
614.50
23.07
23.07
0.00
614.60
23.22
23.22
0.00
614.70
23.38
23.38
0.00
614.80
23.53
23.53
0.00
614.90
23.69
23.69
0.00
615.00
23.84
23.84
0.00
615.10
24.84
23.99
0.85
615.20
26.54
24.14
2.40
615.30
28.71
24.29
4.42
615.40
31.27
24.44
6.83
615.50
34.13
24.59
9.55
615.60
37.28
24.73
12.55
615.70
40.52
24.88
15.64
615.80
43.92
25.03
18.89
615.90
47.67
25.17
22.50
616.00
51.61
25.31
26.30
616.10
55.86
25.46
30.40
616.20
60.30
25.60
34.70
616.30
64.87
25.74
39.13
616.40
69.61
25.88
43.73
616.50
74.43
26.02
48.41
616.60
79.38
26.16
53.23
616.70
84.59
26.29
58.29
616.80
89.95
26.43
63.51
616.90
95.45
26.57
68.88
617.00
101.09
26.70
74.39

2020.17-BMP1 REVISED
Type 11 24-hr 50-yr Concord Rainfall=6.80"
Prepared by Latham -Walters Engineer, Inc. Page 42
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 1/19/2022
Stage -Area -Storage for Pond 3P: (BMP1)
Elevation
Surface
Storage
(feet)
(sq-ft)
(cubic -feet)
609.00
15,725
0
609.10
15,878
1,580
609.20
16,031
3,176
609.30
16,183
4,786
609.40
16,336
6,412
609.50
16,489
8,054
609.60
16,642
9,710
609.70
16,795
11,382
609.80
16,947
13,069
609.90
17,100
14,771
610.00
17,253
16,489
610.10
17,414
18,222
610.20
17,576
19,972
610.30
17,737
21,737
610.40
17,898
23,519
610.50
18,059
25,317
610.60
18,221
27,131
610.70
18,382
28,961
610.80
18,543
30,807
610.90
18,704
32,670
611.00
18,866
34,548
611.10
19,027
36,443
611.20
19,188
38,354
611.30
19,349
40,280
611.40
19,510
42,223
611.50
19,672
44,183
611.60
19,833
46,158
611.70
19,994
48,149
611.80
20,155
50,157
611.90
20,317
52,180
612.00
20,478
54,220
612.10
20,651
56,276
612.20
20,823
58,350
612.30
20,996
60,441
612.40
21,168
62,549
612.50
21,341
64,675
612.60
21,514
66,817
612.70
21,686
68,977
612.80
21,859
71,155
612.90
22,031
73,349
613.00
22,204
75,561
613.10
22,377
77,790
613.20
22,549
80,036
Elevation
Surface
Storage
(feet)
(sq-ft)
(cubic -feet)
613.30
22,722
82,300
613.40
22,894
84,581
613.50
23,067
86,879
613.60
23,240
89,194
613.70
23,412
91,527
613.80
23,585
93,877
613.90
23,757
96,244
614.00
23,930
98,628
614.10
24,114
101,030
614.20
24,298
103,451
614.30
24,482
105,890
614.40
24,665
108,347
614.50
24,849
110,823
614.60
25,033
113,317
614.70
25,217
115,829
614.80
25,401
118,360
614.90
25,585
120,910
615.00
25,769
123,477
615.10
25,952
126,063
615.20
26,136
128,668
615.30
26,320
131,291
615.40
26,504
133,932
615.50
26,688
136,591
615.60
26,872
139,269
615.70
27,055
141,966
615.80
27,239
144,680
615.90
27,423
147,413
616.00
27,607
150,165
616.10
27,799
152,935
616.20
27,992
155,725
616.30
28,184
158,534
616.40
28,376
161,362
616.50
28,569
164,209
616.60
28,761
167,075
616.70
28,953
169,961
616.80
29,145
172,866
616.90
29,338
175,790
617.00
29,530
178,734

SAND FILTER-2
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Mt. Pleasant, NC
Sand Filter Calculation
1. Calculate Runoff Coeff, (Rv)
Drainage area to filter, Ad =
Impervious area to filter forebay=
Impervious percentage =
Rv = 0.05 + 0.9(la) _
2. Calculate req'd water quality volume (WQV)
Brighton Park
2
9.80 ac
4.10 ac.
41.80%
0.42616959
Storage:
Cum
Elev.
Area
Vol.
Vol
634
10132
0
0
636
12767
22899
22899
638
15627
28394
51293
640
18713
34340
85633
Calculate Depth for WQ Volume:
634
0
635.32
15161
636
22899
Elevation of WQ Volume = 635.32
3. Convert Water Quality Volume, WQv to inches of runoff.
WQv = 1.0(Rv) = 0.43 inches
4. Site Hydrologic Input Parameters:
WQV = (Rv/1 x Ad/1 x 43560 sf/1 ac x Rd/1 x ft/12 in)
WQV = 15161 cf (used to size Af)
WQV= 0.3480 ac-ft.
774.11 from Routing
Cn Pre = 74.0
Cn Post = 78.0 to pond
(0.40" from Hydro -Cad)

Table 4.8.3 Results of Hvdrolooic Calculations from HvdroCad
Condition
Q 1- ear
Q 10- r.
Q 25- r
Q 50 yr
Runoff
Pre Dev.
9.88
30.29
39.54
47.97
Post. Dev.
19.28
50.45
63.96
76.09
Routed
0.57
3.90
16.46
24.59
Peak Stage
635.97
638.17
638.58
639.11
Disch. Time
1135 hours
1
1
1.9' Freeboard
Required
5. First 1/2 inch 0.41 ac-ft 17787 cf
Detain 18 hrs 21436 cf Provided
36 hrs 14017 cf
Release Peak-36 hrs 23627 Provided
6. Channel Protection Volume: CPv to be held for 24 hours + 12 hours = 36 hours
S = 1000/Cn-10 where Cn = 78.0
S = 2.82 inches
Compute total runoff for the 1-year, 24-hour storm event. Total rainfall depth is
Qd = (P-0.2S)^2/(P+0.8S) 2.9 1-year storm
Qd= 1.06 inches
Watershed Runoff = (Qd)(DA)(1 ft/12") = 0.86 ac-ft. = 0.854 per Hydro -CAD
From HydroCad- Max Release Rate = 0.57 cfs
From HydroCad: Maximum Stage: 635.97
Storage: 22362 cf
Drawdown Time: 135 hours
7. Sedimentation Basin Surface Area
As = 0.066 x WQV = As = 1001 sf
8. Sand Filter Bed Surface Area (Af)
1414 sf
Af = (WQV x df)/(k x t x (ha + df) ha = average head
df = 1.5 (depth of filter media)
hmax = 1.32
OK
Calculate Ha = hmax/2 = 0.66206197 ft
Where df = depth of filter bed (15), k = permeability of sand (3.5), ha = avg depth, t=51 hrs=2.125 days
Af = 1414 sf 206.47 cf/hr = 0.0573537 cfs
hmax = 1.32 15161 cf/(As + Af)
Choose As + Af = 11449.5 sf (WQV/Hmax)
As = Af = 5724.75 Per plan, As = 3702
Af = 6430 total Area
Total 12000

9. Sand Filter Drawdown Calculation
Coeff. Of Permeability of filter media = 3.5ft/day = 0.146 ft/hr
Volume of water drained in one hour = 0.146 ft/hr x Af s.f. = 206.4734 cf/hour
Drawdown Time = WQV/Drawdown Rate = 73.43 hrs 3.059425 days
Underdrain Calculations:
78 I.f of underdrain shown; provide 6" perforated pvc pipe with 3/8" perforations spaces 3" o.c. - 4 longitudinal rows
spaced 90 degrees apart.
94 I.f. of pipe
94 I.f. x 4 rows/ft x 4 holes/ft = 1504 holes
50% of perforations = 752 holes
Capacity of one hole = 0.0083 cfs based upon CA(2gh)^0.5
Total Capacity = 6.2416 cfs which is 108.8 times the capacity of the sand filter.
Total Capacityof 6" PVC @ 0.50% is 0.40 cfs (0.20 cfs assuming 50% clogged) from Mannings and BMP Manual.
10. Antiflotation Calculation
7.5 Height of Riser, ft.
6 Area of Riser, s.f.
45 Volume of Riser, c.f.
2808 Weight of Water @ 62.4 pcf
3088.8 Weight of water with safety factor of 1.1
82.6 Buoyant Wt. of Concrete = (145-62.4) pcf
1.38 Volume of Concrete Req'd in c.y.
37.39 Volume of Concrete Req'd in c.f.
45 Volume of Concrete in Structure (cf)
-7.61 Volume of Concrete Required (cf)
0.5 ft thick
2.8 Length/Width
(If negative, additional concrete weight not required)

Brighton Park
Mt. Pleasant, NC
1. Develop Stage -Discharge Data for Sand Filter Media.
From 4.8.18 of the BMP Standards Manual:
Q = Af(k)(h+df)/(df)
Latham -Walters Engineering, Inc.
16507-A Northcross Drive
Huntersville, NC 28078
where Af = surface area of filter bed = sf
df = filter bed depth, ft. = ft.
k = coefficient of permeability of filter media (ft/day) = ft/day
h = average height of water above filter bed (ft) 12, etc.
h
Q
cf/day
Q
cfs
1
8249.509
0.095
2
11549.31
0.134
3
14849.12
0.172
4
18148.92
0.210
5
21448.72
0.248
6
24748.53
0.286
7
28048.33
0.325
8
31348.13
0.363
9
34647.94
0.401
10
37947.74
0.439

is
(Predeveloped)
( 2S� � 3P
(Post Developed)
Subcat Reach on Link
(BMP2)

2020.17-BM P2
Prepared by {enter your company name here} Page 2
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 8/4/2022
Area Listing (all nodes)
Area (acres) CN Description (subcats)
3.280 69 Pasture/grassland/range, Fair, HSG B (1S)
3.090 73 Woods, Fair, HSG C (1 S)
6.520 75 RM-2 (B) (2S)
3.430 79 Pasture/grassland/range, Fair, HSG C (1S)
3.280 83 RM-2 (C) (2S)
iiBil-iiI1]

2020.17-BMP2 Type 11 24-hr 1-yr Concord Rainfall=2.90"
Prepared by {enter your company name here} Page 3
HvdroCAD® 8.00 s/n 004317 © 2006 HvdroCAD Software Solutions LLC 8/4/2022
Time span=0.00-200.00 hrs, dt=0.01 hrs, 20001 points
Runoff by SCS TR-20 method, UH=SCS
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment 1S: (Predeveloped) Runoff Area=9.800 ac Runoff Depth=0.85"
Flow Length=729' Tc=15.7 min CN=74 Runoff=9.88 cfs 0.690 of
Subcatchment 2S: (Post Developed) Runoff Area=9.800 ac Runoff Depth=1.06"
Tc=5.0 min CN=78 Runoff=19.28 cfs 0.864 of
Pond 3P: (BMP2) Peak Elev=635.97' Storage=22,492 cf Inflow=19.28 cfs 0.864 of
Primary=0.58 cfs 0.863 of Secondary=0.00 cfs 0.000 of Outflow=0.58 cfs 0.863 of
Total Runoff Area = 19.600 ac Runoff Volume = 1.555 of Average Runoff Depth = 0.95"
100.00% Pervious Area = 19.600 ac 0.00% Impervious Area = 0.000 ac

2020.17-BMP2 Type 11 24-hr 1-yr Concord Rainfall=2.90"
Prepared by {enter your company name here} Page 4
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 8/4/2022
Subcatchment 1S: (Predeveloped)
BASED ON EXISTING CONDITIONS
Runoff = 9.88 cfs @ 12.09 hrs, Volume= 0.690 af, Depth= 0.85"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Type II 24-hr 1-yr Concord Rainfall=2.90"
Area (ac) CN Description
3.090
73
Woods, Fair, HSG C
3.430
79
Pasture/grassland/range, Fair, HSG C
3.280
69
Pasture/grassland/range, Fair, HSG B
9.800
74
Weighted Average
9.800
Pervious Area
Tc
Length
Slope
Velocity
Capacity Description
(min)
(feet)
(ft/ft)
(ft/sec)
(cfs)
8.9
100
0.0586
0.19
Sheet Flow,
Grass: Dense n= 0.240 P2= 3.50"
6.8
629
0.0482
1.54
Shallow Concentrated Flow,
Short Grass Pasture Kv= 7.0 fps
15.7 729 Total

2020.17-BM P2
Type // 24-hr 1-yr Concord Rainfall=2.90"
Prepared by {enter your company name here} Page 5
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 8/4/2022
Hydrograph for Subcatchment 1S: (Predeveloped)
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
0.00
0.00
0.00
0.00
2.00
0.06
0.00
0.00
4.00
0.14
0.00
0.00
6.00
0.23
0.00
0.00
8.00
0.35
0.00
0.00
10.00
0.52
0.00
0.00
12.00
1.92
0.31
7.03
14.00
2.38
0.54
0.64
16.00
2.55
0.64
0.40
18.00
2.67
0.71
0.31
20.00
2.76
0.76
0.23
22.00
2.83
0.80
0.21
24.00
2.90
0.85
0.20
26.00
2.90
0.85
0.00
28.00
2.90
0.85
0.00
30.00
2.90
0.85
0.00
32.00
2.90
0.85
0.00
34.00
2.90
0.85
0.00
36.00
2.90
0.85
0.00
38.00
2.90
0.85
0.00
40.00
2.90
0.85
0.00
42.00
2.90
0.85
0.00
44.00
2.90
0.85
0.00
46.00
2.90
0.85
0.00
48.00
2.90
0.85
0.00
50.00
2.90
0.85
0.00
52.00
2.90
0.85
0.00
54.00
2.90
0.85
0.00
56.00
2.90
0.85
0.00
58.00
2.90
0.85
0.00
60.00
2.90
0.85
0.00
62.00
2.90
0.85
0.00
64.00
2.90
0.85
0.00
66.00
2.90
0.85
0.00
68.00
2.90
0.85
0.00
70.00
2.90
0.85
0.00
72.00
2.90
0.85
0.00
74.00
2.90
0.85
0.00
76.00
2.90
0.85
0.00
78.00
2.90
0.85
0.00
80.00
2.90
0.85
0.00
82.00
2.90
0.85
0.00
84.00
2.90
0.85
0.00
86.00
2.90
0.85
0.00
88.00
2.90
0.85
0.00
90.00
2.90
0.85
0.00
92.00
2.90
0.85
0.00
94.00
2.90
0.85
0.00
96.00
2.90
0.85
0.00
98.00
2.90
0.85
0.00
100.00
2.90
0.85
0.00
102.00
2.90
0.85
0.00
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
104.00
2.90
0.85
0.00
106.00
2.90
0.85
0.00
108.00
2.90
0.85
0.00
110.00
2.90
0.85
0.00
112.00
2.90
0.85
0.00
114.00
2.90
0.85
0.00
116.00
2.90
0.85
0.00
118.00
2.90
0.85
0.00
120.00
2.90
0.85
0.00
122.00
2.90
0.85
0.00
124.00
2.90
0.85
0.00
126.00
2.90
0.85
0.00
128.00
2.90
0.85
0.00
130.00
2.90
0.85
0.00
132.00
2.90
0.85
0.00
134.00
2.90
0.85
0.00
136.00
2.90
0.85
0.00
138.00
2.90
0.85
0.00
140.00
2.90
0.85
0.00
142.00
2.90
0.85
0.00
144.00
2.90
0.85
0.00
146.00
2.90
0.85
0.00
148.00
2.90
0.85
0.00
150.00
2.90
0.85
0.00
152.00
2.90
0.85
0.00
154.00
2.90
0.85
0.00
156.00
2.90
0.85
0.00
158.00
2.90
0.85
0.00
160.00
2.90
0.85
0.00
162.00
2.90
0.85
0.00
164.00
2.90
0.85
0.00
166.00
2.90
0.85
0.00
168.00
2.90
0.85
0.00
170.00
2.90
0.85
0.00
172.00
2.90
0.85
0.00
174.00
2.90
0.85
0.00
176.00
2.90
0.85
0.00
178.00
2.90
0.85
0.00
180.00
2.90
0.85
0.00
182.00
2.90
0.85
0.00
184.00
2.90
0.85
0.00
186.00
2.90
0.85
0.00
188.00
2.90
0.85
0.00
190.00
2.90
0.85
0.00
192.00
2.90
0.85
0.00
194.00
2.90
0.85
0.00
196.00
2.90
0.85
0.00
198.00
2.90
0.85
0.00
200.00
2.90
0.85
0.00

2020.17-BM P2 Type 11 24-hr 1-yr Concord Rainfall=2.90"
Prepared by {enter your company name here} Page 6
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 8/4/2022
Subcatchment 2S: (Post Developed)
Runoff = 19.28 cfs @ 11.97 hrs, Volume= 0.864 af, Depth= 1.06"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Type II 24-hr 1-yr Concord Rainfall=2.90"
Area (ac) CN
Description
3.280 83
RM-2 (C)
6.520 75
RM-2 (B)
9.800 78
Weighted Average
9.800
Pervious Area
Tc Length
Slope Velocity Capacity Description
(min) (feet)
(ft/ft) (ft/sec) (cfs)
5.0
Direct Entry,

2020.17-BM P2
Type // 24-hr 1-yr Concord Rainfall=2.90"
Prepared by {enter your company name here} Page 7
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 8/4/2022
Hydrograph for Subcatchment 2S: (Post Developed)
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
0.00
0.00
0.00
0.00
2.00
0.06
0.00
0.00
4.00
0.14
0.00
0.00
6.00
0.23
0.00
0.00
8.00
0.35
0.00
0.00
10.00
0.52
0.00
0.00
12.00
1.92
0.44
17.03
14.00
2.38
0.71
0.69
16.00
2.55
0.82
0.44
18.00
2.67
0.90
0.35
20.00
2.76
0.96
0.26
22.00
2.83
1.01
0.24
24.00
2.90
1.06
0.22
26.00
2.90
1.06
0.00
28.00
2.90
1.06
0.00
30.00
2.90
1.06
0.00
32.00
2.90
1.06
0.00
34.00
2.90
1.06
0.00
36.00
2.90
1.06
0.00
38.00
2.90
1.06
0.00
40.00
2.90
1.06
0.00
42.00
2.90
1.06
0.00
44.00
2.90
1.06
0.00
46.00
2.90
1.06
0.00
48.00
2.90
1.06
0.00
50.00
2.90
1.06
0.00
52.00
2.90
1.06
0.00
54.00
2.90
1.06
0.00
56.00
2.90
1.06
0.00
58.00
2.90
1.06
0.00
60.00
2.90
1.06
0.00
62.00
2.90
1.06
0.00
64.00
2.90
1.06
0.00
66.00
2.90
1.06
0.00
68.00
2.90
1.06
0.00
70.00
2.90
1.06
0.00
72.00
2.90
1.06
0.00
74.00
2.90
1.06
0.00
76.00
2.90
1.06
0.00
78.00
2.90
1.06
0.00
80.00
2.90
1.06
0.00
82.00
2.90
1.06
0.00
84.00
2.90
1.06
0.00
86.00
2.90
1.06
0.00
88.00
2.90
1.06
0.00
90.00
2.90
1.06
0.00
92.00
2.90
1.06
0.00
94.00
2.90
1.06
0.00
96.00
2.90
1.06
0.00
98.00
2.90
1.06
0.00
100.00
2.90
1.06
0.00
102.00
2.90
1.06
0.00
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
104.00
2.90
1.06
0.00
106.00
2.90
1.06
0.00
108.00
2.90
1.06
0.00
110.00
2.90
1.06
0.00
112.00
2.90
1.06
0.00
114.00
2.90
1.06
0.00
116.00
2.90
1.06
0.00
118.00
2.90
1.06
0.00
120.00
2.90
1.06
0.00
122.00
2.90
1.06
0.00
124.00
2.90
1.06
0.00
126.00
2.90
1.06
0.00
128.00
2.90
1.06
0.00
130.00
2.90
1.06
0.00
132.00
2.90
1.06
0.00
134.00
2.90
1.06
0.00
136.00
2.90
1.06
0.00
138.00
2.90
1.06
0.00
140.00
2.90
1.06
0.00
142.00
2.90
1.06
0.00
144.00
2.90
1.06
0.00
146.00
2.90
1.06
0.00
148.00
2.90
1.06
0.00
150.00
2.90
1.06
0.00
152.00
2.90
1.06
0.00
154.00
2.90
1.06
0.00
156.00
2.90
1.06
0.00
158.00
2.90
1.06
0.00
160.00
2.90
1.06
0.00
162.00
2.90
1.06
0.00
164.00
2.90
1.06
0.00
166.00
2.90
1.06
0.00
168.00
2.90
1.06
0.00
170.00
2.90
1.06
0.00
172.00
2.90
1.06
0.00
174.00
2.90
1.06
0.00
176.00
2.90
1.06
0.00
178.00
2.90
1.06
0.00
180.00
2.90
1.06
0.00
182.00
2.90
1.06
0.00
184.00
2.90
1.06
0.00
186.00
2.90
1.06
0.00
188.00
2.90
1.06
0.00
190.00
2.90
1.06
0.00
192.00
2.90
1.06
0.00
194.00
2.90
1.06
0.00
196.00
2.90
1.06
0.00
198.00
2.90
1.06
0.00
200.00
2.90
1.06
0.00

2020.17-BMP2 Type 11 24-hr 1-yr Concord Rainfall=2.90"
Prepared by {enter your company name here} Page 8
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 8/4/2022
Pond 3P: (BMP2)
Inflow Area = 9.800 ac, Inflow Depth = 1.06" for 1-yr Concord event
Inflow =
19.28 cfs @
11.97 hrs,
Volume=
0.864 of
Outflow =
0.58 cfs @
14.89 hrs,
Volume=
0.863 af, Atten= 97%, Lag= 175.5 min
Primary =
0.58 cfs @
14.89 hrs,
Volume=
0.863 of
Secondary =
0.00 cfs @
0.00 hrs,
Volume=
0.000 of
Routing by Stor-Ind method, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Peak Elev= 635.97' @ 14.89 hrs Surf.Area= 12,725 sf Storage= 22,492 cf
Plug -Flow detention time= 1,392.8 min calculated for 0.863 of (100% of inflow)
Center -of -Mass det. time= 1,392.3 min ( 2,242.8 - 850.4 )
Volume Invert Avail.Storage Storage Description
#1 634.00' 85,633 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic -feet) (cubic -feet)
634.00 10,132 0 0
636.00 12,767 22,899 22,899
638.00 15,627 28,394 51,293
640.00 18,713 34,340 85,633
Device Routing Invert Outlet Devices
#1 Primary 630.40' 18.0" x 126.0' long Culvert RCP, square edge headwall, Ke= 0.500
Outlet Invert= 617.77' S= 0.1002 7' Cc= 0.900 n= 0.013
#2 Device 1 634.00' Exfiltration
Head (feet) 0.00 1.00 2.00 3.00 4.00 5.00 6.00
Disch. (cfs) 0.000 0.095 0.134 0.172 0.210 0.248 0.286
#3 Device 1 635.50' 6.0" Vert. Orifice/Grate C= 0.600
#4 Device 1 638.00' 2.00' x 3.00' Horiz. Top of Riser Limited to weir flow C= 0.600
#5 Secondary 639.00' 10.0' long x 16.0' breadth Spillway
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Coef. (English) 2.68 2.70 2.70 2.64 2.63 2.64 2.64 2.63
Primary OutFlow Max=0.58 cfs @ 14.89 hrs HW=635.97' (Free Discharge)
L1=Culvert (Passes 0.58 cfs of 18.68 cfs potential flow)
2=Exfltration (Custom Controls 0.13 cfs)
3=Orifice/Grate (Orifice Controls 0.45 cfs @ 2.33 fps)
=Top of Riser ( Controls 0.00 cfs)
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=634.00' (Free Discharge)
5=Spillway ( Controls 0.00 cfs)

2020.17-BM P2
Type // 24-hr 1-yr Concord Rainfall=2.90"
Prepared by {enter your company name here} Page 9
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 8/4/2022
Hydrograph for Pond 3P: (BMP2)
Time
Inflow
Storage
Elevation
Outflow
Primary
Secondary
(hours)
(cfs)
(cubic -feet)
(feet)
(cfs)
(cfs)
(cfs)
0.00
0.00
0
634.00
0.00
0.00
0.00
5.00
0.00
0
634.00
0.00
0.00
0.00
10.00
0.00
0
634.00
0.00
0.00
0.00
15.00
0.56
22,489
635.97
0.58
0.58
0.00
20.00
0.26
20,559
635.81
0.38
0.38
0.00
25.00
0.00
18,718
635.67
0.20
0.20
0.00
30.00
0.00
16,257
635.46
0.11
0.11
0.00
35.00
0.00
14,279
635.30
0.11
0.11
0.00
40.00
0.00
12,415
635.14
0.10
0.10
0.00
45.00
0.00
10,660
634.99
0.09
0.09
0.00
50.00
0.00
9,091
634.85
0.08
0.08
0.00
55.00
0.00
7,742
634.73
0.07
0.07
0.00
60.00
0.00
6,587
634.62
0.06
0.06
0.00
65.00
0.00
5,598
634.53
0.05
0.05
0.00
70.00
0.00
4,754
634.46
0.04
0.04
0.00
75.00
0.00
4,033
634.39
0.04
0.04
0.00
80.00
0.00
3,420
634.33
0.03
0.03
0.00
85.00
0.00
2,899
634.28
0.03
0.03
0.00
90.00
0.00
2,455
634.24
0.02
0.02
0.00
95.00
0.00
2,079
634.20
0.02
0.02
0.00
100.00
0.00
1,760
634.17
0.02
0.02
0.00
105.00
0.00
1,489
634.15
0.01
0.01
0.00
110.00
0.00
1,260
634.12
0.01
0.01
0.00
115.00
0.00
1,066
634.10
0.01
0.01
0.00
120.00
0.00
901
634.09
0.01
0.01
0.00
125.00
0.00
762
634.07
0.01
0.01
0.00
130.00
0.00
644
634.06
0.01
0.01
0.00
135.00
0.00
544
634.05
0.01
0.01
0.00
140.00
0.00
460
634.05
0.00
0.00
0.00
145.00
0.00
389
634.04
0.00
0.00
0.00
150.00
0.00
329
634.03
0.00
0.00
0.00
155.00
0.00
278
634.03
0.00
0.00
0.00
160.00
0.00
235
634.02
0.00
0.00
0.00
165.00
0.00
199
634.02
0.00
0.00
0.00
170.00
0.00
168
634.02
0.00
0.00
0.00
175.00
0.00
142
634.01
0.00
0.00
0.00
180.00
0.00
120
634.01
0.00
0.00
0.00
185.00
0.00
101
634.01
0.00
0.00
0.00
190.00
0.00
86
634.01
0.00
0.00
0.00
195.00
0.00
72
634.01
0.00
0.00
0.00
200.00
0.00
61
634.01
0.00
0.00
0.00

2020.17-BM P2
Type 11 24-hr 1-yr Concord Rainfall=2.90"
Prepared by {enter your company name here} Page 10
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 8/4/2022
Stage -Discharge for Pond 3P: (BMP2)
Elevation Discharge Primary Secondary
(feet)
(cfs)
(cfs)
(cfs)
634.00
0.00
0.00
0.00
634.10
0.01
0.01
0.00
634.20
0.02
0.02
0.00
634.30
0.03
0.03
0.00
634.40
0.04
0.04
0.00
634.50
0.05
0.05
0.00
634.60
0.06
0.06
0.00
634.70
0.07
0.07
0.00
634.80
0.08
0.08
0.00
634.90
0.09
0.09
0.00
635.00
0.10
0.10
0.00
635.10
0.10
0.10
0.00
635.20
0.10
0.10
0.00
635.30
0.11
0.11
0.00
635.40
0.11
0.11
0.00
635.50
0.11
0.11
0.00
635.60
0.15
0.15
0.00
635.70
0.23
0.23
0.00
635.80
0.36
0.36
0.00
635.90
0.49
0.49
0.00
636.00
0.61
0.61
0.00
636.10
0.70
0.70
0.00
636.20
0.78
0.78
0.00
636.30
0.85
0.85
0.00
636.40
0.91
0.91
0.00
636.50
0.97
0.97
0.00
636.60
1.03
1.03
0.00
636.70
1.08
1.08
0.00
636.80
1.13
1.13
0.00
636.90
1.18
1.18
0.00
637.00
1.23
1.23
0.00
637.10
1.27
1.27
0.00
637.20
1.32
1.32
0.00
637.30
1.36
1.36
0.00
637.40
1.40
1.40
0.00
637.50
1.44
1.44
0.00
637.60
1.48
1.48
0.00
637.70
1.52
1.52
0.00
637.80
1.56
1.56
0.00
637.90
1.59
1.59
0.00
638.00
1.63
1.63
0.00
638.10
2.70
2.70
0.00
638.20
4.62
4.62
0.00
638.30
7.10
7.10
0.00
638.40
10.04
10.04
0.00
638.50
13.36
13.36
0.00
638.60
17.03
17.03
0.00
638.70
21.01
21.01
0.00
638.80
23.53
23.53
0.00
638.90
23.69
23.69
0.00
639.00
23.84
23.84
0.00
639.10
24.84
23.99
0.85
Elevation Discharge Primary Secondary
(feet)
(cfs)
(cfs)
(cfs)
639.20
26.54
24.14
2.40
639.30
28.71
24.29
4.42
639.40
31.27
24.44
6.83
639.50
34.13
24.59
9.55
639.60
37.28
24.73
12.55
639.70
40.52
24.88
15.64
639.80
43.92
25.03
18.89
639.90
47.67
25.17
22.50
640.00
51.61
25.31
26.30

2020.17-BM P2
Type 11 24-hr 1-yr Concord Rainfall=2.90"
Prepared by {enter your company name here} Page 11
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 8/4/2022
Stage -Area -Storage for Pond 3P: (BMP2)
Elevation
Surface
Storage
(feet)
(sq-ft)
(cubic -feet)
634.00
10,132
0
634.10
10,264
1,020
634.20
10,396
2,053
634.30
10,527
3,099
634.40
10,659
4,158
634.50
10,791
5,231
634.60
10,923
6,316
634.70
11,054
7,415
634.80
11,186
8,527
634.90
11,318
9,652
635.00
11,450
10,791
635.10
11,581
11,942
635.20
11,713
13,107
635.30
11,845
14,285
635.40
11,976
15,476
635.50
12,108
16,680
635.60
12,240
17,898
635.70
12,372
19,128
635.80
12,503
20,372
635.90
12,635
21,629
636.00
12,767
22,899
636.10
12,910
24,183
636.20
13,053
25,481
636.30
13,196
26,793
636.40
13,339
28,120
636.50
13,482
29,461
636.60
13,625
30,817
636.70
13,768
32,186
636.80
13,911
33,570
636.90
14,054
34,968
637.00
14,197
36,381
637.10
14,340
37,808
637.20
14,483
39,249
637.30
14,626
40,704
637.40
14,769
42,174
637.50
14,912
43,658
637.60
15,055
45,157
637.70
15,198
46,669
637.80
15,341
48,196
637.90
15,484
49,737
638.00
15,627
51,293
638.10
15,781
52,863
638.20
15,936
54,449
638.30
16,090
56,051
638.40
16,244
57,667
638.50
16,399
59,299
638.60
16,553
60,947
638.70
16,707
62,610
638.80
16,861
64,288
638.90
17,016
65,982
639.00
17,170
67,692
639.10
17,324
69,416
Elevation
Surface
Storage
(feet)
(sq-ft)
(cubic -feet)
639.20
17,479
71,156
639.30
17,633
72,912
639.40
17,787
74,683
639.50
17,942
76,469
639.60
18,096
78,271
639.70
18,250
80,089
639.80
18,404
81,921
639.90
18,559
83,769
640.00
18,713
85,633

2020.17-BM P2 Type 11 24-hr 10-yr Concord Rainfall=5.10"
Prepared by {enter your company name here} Page 12
HvdroCAD® 8.00 s/n 004317 © 2006 HvdroCAD Software Solutions LLC 8/4/2022
Time span=0.00-200.00 hrs, dt=0.01 hrs, 20001 points
Runoff by SCS TR-20 method, UH=SCS
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment 1S: (Predeveloped) Runoff Area=9.800 ac Runoff Depth=2.44"
Flow Length=729' Tc=15.7 min CN=74 Runoff=30.29 cfs 1.996 of
Subcatchment 2S: (Post Developed) Runoff Area=9.800 ac Runoff Depth=2.80"
Tc=5.0 min CN=78 Runoff=50.45 cfs 2.284 of
Pond 3P: (BMP2) Peak Elev=638.16' Storage=53,891 cf Inflow=50.45 cfs 2.284 of
Primary=3.90 cfs 2.282 of Secondary=0.00 cfs 0.000 of Outflow=3.90 cfs 2.282 of
Total Runoff Area = 19.600 ac Runoff Volume = 4.280 of Average Runoff Depth = 2.62"
100.00% Pervious Area = 19.600 ac 0.00% Impervious Area = 0.000 ac

2020.17-BM P2 Type 11 24-hr 10-yr Concord Rainfall=5.10"
Prepared by {enter your company name here} Page 13
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 8/4/2022
Subcatchment 1S: (Predeveloped)
BASED ON EXISTING CONDITIONS
Runoff = 30.29 cfs @ 12.08 hrs, Volume= 1.996 af, Depth= 2.44"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Type II 24-hr 10-yr Concord Rainfall=5.10"
Area (ac) CN Description
3.090
73
Woods, Fair, HSG C
3.430
79
Pasture/grassland/range, Fair, HSG C
3.280
69
Pasture/grassland/range, Fair, HSG B
9.800
74
Weighted Average
9.800
Pervious Area
Tc
Length
Slope
Velocity
Capacity Description
(min)
(feet)
(ft/ft)
(ft/sec)
(cfs)
8.9
100
0.0586
0.19
Sheet Flow,
Grass: Dense n= 0.240 P2= 3.50"
6.8
629
0.0482
1.54
Shallow Concentrated Flow,
Short Grass Pasture Kv= 7.0 fps
15.7 729 Total

2020.17-BM P2
Type 11 24-hr 10-yr Concord Rainfall=5.10"
Prepared by {enter your company name here} Page 14
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 8/4/2022
Hydrograph for Subcatchment 1S: (Predeveloped)
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
0.00
0.00
0.00
0.00
2.00
0.11
0.00
0.00
4.00
0.24
0.00
0.00
6.00
0.41
0.00
0.00
8.00
0.61
0.00
0.00
10.00
0.92
0.01
0.17
12.00
3.38
1.16
23.98
14.00
4.18
1.73
1.57
16.00
4.49
1.96
0.95
18.00
4.70
2.13
0.73
20.00
4.86
2.25
0.54
22.00
4.98
2.35
0.49
24.00
5.10
2.44
0.45
26.00
5.10
2.44
0.00
28.00
5.10
2.44
0.00
30.00
5.10
2.44
0.00
32.00
5.10
2.44
0.00
34.00
5.10
2.44
0.00
36.00
5.10
2.44
0.00
38.00
5.10
2.44
0.00
40.00
5.10
2.44
0.00
42.00
5.10
2.44
0.00
44.00
5.10
2.44
0.00
46.00
5.10
2.44
0.00
48.00
5.10
2.44
0.00
50.00
5.10
2.44
0.00
52.00
5.10
2.44
0.00
54.00
5.10
2.44
0.00
56.00
5.10
2.44
0.00
58.00
5.10
2.44
0.00
60.00
5.10
2.44
0.00
62.00
5.10
2.44
0.00
64.00
5.10
2.44
0.00
66.00
5.10
2.44
0.00
68.00
5.10
2.44
0.00
70.00
5.10
2.44
0.00
72.00
5.10
2.44
0.00
74.00
5.10
2.44
0.00
76.00
5.10
2.44
0.00
78.00
5.10
2.44
0.00
80.00
5.10
2.44
0.00
82.00
5.10
2.44
0.00
84.00
5.10
2.44
0.00
86.00
5.10
2.44
0.00
88.00
5.10
2.44
0.00
90.00
5.10
2.44
0.00
92.00
5.10
2.44
0.00
94.00
5.10
2.44
0.00
96.00
5.10
2.44
0.00
98.00
5.10
2.44
0.00
100.00
5.10
2.44
0.00
102.00
5.10
2.44
0.00
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
104.00
5.10
2.44
0.00
106.00
5.10
2.44
0.00
108.00
5.10
2.44
0.00
110.00
5.10
2.44
0.00
112.00
5.10
2.44
0.00
114.00
5.10
2.44
0.00
116.00
5.10
2.44
0.00
118.00
5.10
2.44
0.00
120.00
5.10
2.44
0.00
122.00
5.10
2.44
0.00
124.00
5.10
2.44
0.00
126.00
5.10
2.44
0.00
128.00
5.10
2.44
0.00
130.00
5.10
2.44
0.00
132.00
5.10
2.44
0.00
134.00
5.10
2.44
0.00
136.00
5.10
2.44
0.00
138.00
5.10
2.44
0.00
140.00
5.10
2.44
0.00
142.00
5.10
2.44
0.00
144.00
5.10
2.44
0.00
146.00
5.10
2.44
0.00
148.00
5.10
2.44
0.00
150.00
5.10
2.44
0.00
152.00
5.10
2.44
0.00
154.00
5.10
2.44
0.00
156.00
5.10
2.44
0.00
158.00
5.10
2.44
0.00
160.00
5.10
2.44
0.00
162.00
5.10
2.44
0.00
164.00
5.10
2.44
0.00
166.00
5.10
2.44
0.00
168.00
5.10
2.44
0.00
170.00
5.10
2.44
0.00
172.00
5.10
2.44
0.00
174.00
5.10
2.44
0.00
176.00
5.10
2.44
0.00
178.00
5.10
2.44
0.00
180.00
5.10
2.44
0.00
182.00
5.10
2.44
0.00
184.00
5.10
2.44
0.00
186.00
5.10
2.44
0.00
188.00
5.10
2.44
0.00
190.00
5.10
2.44
0.00
192.00
5.10
2.44
0.00
194.00
5.10
2.44
0.00
196.00
5.10
2.44
0.00
198.00
5.10
2.44
0.00
200.00
5.10
2.44
0.00

2020.17-BM P2 Type 11 24-hr 10-yr Concord Rainfall=5.10"
Prepared by {enter your company name here} Page 15
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 8/4/2022
Subcatchment 2S: (Post Developed)
Runoff = 50.45 cfs @ 11.96 hrs, Volume= 2.284 af, Depth= 2.80"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Type II 24-hr 10-yr Concord Rainfall=5.10"
Area (ac) CN
Description
3.280 83
RM-2 (C)
6.520 75
RM-2 (B)
9.800 78
Weighted Average
9.800
Pervious Area
Tc Length
Slope Velocity Capacity Description
(min) (feet)
(ft/ft) (ft/sec) (cfs)
5.0
Direct Entry,

2020.17-BM P2
Type 11 24-hr 10-yr Concord Rainfall=5.10"
Prepared by {enter your company name here} Page 16
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 8/4/2022
Hydrograph for Subcatchment 2S: (Post Developed)
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
0.00
0.00
0.00
0.00
2.00
0.11
0.00
0.00
4.00
0.24
0.00
0.00
6.00
0.41
0.00
0.00
8.00
0.61
0.00
0.03
10.00
0.92
0.04
0.40
12.00
3.38
1.41
43.25
14.00
4.18
2.03
1.57
16.00
4.49
2.28
0.98
18.00
4.70
2.46
0.77
20.00
4.86
2.59
0.56
22.00
4.98
2.70
0.51
24.00
5.10
2.80
0.47
26.00
5.10
2.80
0.00
28.00
5.10
2.80
0.00
30.00
5.10
2.80
0.00
32.00
5.10
2.80
0.00
34.00
5.10
2.80
0.00
36.00
5.10
2.80
0.00
38.00
5.10
2.80
0.00
40.00
5.10
2.80
0.00
42.00
5.10
2.80
0.00
44.00
5.10
2.80
0.00
46.00
5.10
2.80
0.00
48.00
5.10
2.80
0.00
50.00
5.10
2.80
0.00
52.00
5.10
2.80
0.00
54.00
5.10
2.80
0.00
56.00
5.10
2.80
0.00
58.00
5.10
2.80
0.00
60.00
5.10
2.80
0.00
62.00
5.10
2.80
0.00
64.00
5.10
2.80
0.00
66.00
5.10
2.80
0.00
68.00
5.10
2.80
0.00
70.00
5.10
2.80
0.00
72.00
5.10
2.80
0.00
74.00
5.10
2.80
0.00
76.00
5.10
2.80
0.00
78.00
5.10
2.80
0.00
80.00
5.10
2.80
0.00
82.00
5.10
2.80
0.00
84.00
5.10
2.80
0.00
86.00
5.10
2.80
0.00
88.00
5.10
2.80
0.00
90.00
5.10
2.80
0.00
92.00
5.10
2.80
0.00
94.00
5.10
2.80
0.00
96.00
5.10
2.80
0.00
98.00
5.10
2.80
0.00
100.00
5.10
2.80
0.00
102.00
5.10
2.80
0.00
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
104.00
5.10
2.80
0.00
106.00
5.10
2.80
0.00
108.00
5.10
2.80
0.00
110.00
5.10
2.80
0.00
112.00
5.10
2.80
0.00
114.00
5.10
2.80
0.00
116.00
5.10
2.80
0.00
118.00
5.10
2.80
0.00
120.00
5.10
2.80
0.00
122.00
5.10
2.80
0.00
124.00
5.10
2.80
0.00
126.00
5.10
2.80
0.00
128.00
5.10
2.80
0.00
130.00
5.10
2.80
0.00
132.00
5.10
2.80
0.00
134.00
5.10
2.80
0.00
136.00
5.10
2.80
0.00
138.00
5.10
2.80
0.00
140.00
5.10
2.80
0.00
142.00
5.10
2.80
0.00
144.00
5.10
2.80
0.00
146.00
5.10
2.80
0.00
148.00
5.10
2.80
0.00
150.00
5.10
2.80
0.00
152.00
5.10
2.80
0.00
154.00
5.10
2.80
0.00
156.00
5.10
2.80
0.00
158.00
5.10
2.80
0.00
160.00
5.10
2.80
0.00
162.00
5.10
2.80
0.00
164.00
5.10
2.80
0.00
166.00
5.10
2.80
0.00
168.00
5.10
2.80
0.00
170.00
5.10
2.80
0.00
172.00
5.10
2.80
0.00
174.00
5.10
2.80
0.00
176.00
5.10
2.80
0.00
178.00
5.10
2.80
0.00
180.00
5.10
2.80
0.00
182.00
5.10
2.80
0.00
184.00
5.10
2.80
0.00
186.00
5.10
2.80
0.00
188.00
5.10
2.80
0.00
190.00
5.10
2.80
0.00
192.00
5.10
2.80
0.00
194.00
5.10
2.80
0.00
196.00
5.10
2.80
0.00
198.00
5.10
2.80
0.00
200.00
5.10
2.80
0.00

2020.17-BM P2 Type 11 24-hr 10-yr Concord Rainfall=5.10"
Prepared by {enter your company name here} Page 17
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 8/4/2022
Pond 3P: (BMP2)
Inflow Area = 9.800 ac, Inflow Depth = 2.80" for 10-yr Concord event
Inflow =
50.45 cfs @
11.96 hrs,
Volume=
2.284 of
Outflow =
3.90 cfs @
12.52 hrs,
Volume=
2.282 af, Atten= 92%, Lag= 33.6 min
Primary =
3.90 cfs @
12.52 hrs,
Volume=
2.282 of
Secondary =
0.00 cfs @
0.00 hrs,
Volume=
0.000 of
Routing by Stor-Ind method, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Peak Elev= 638.16' @ 12.52 hrs Surf.Area= 15,881 sf Storage= 53,891 cf
Plug -Flow detention time= 762.1 min calculated for 2.282 of (100% of inflow)
Center -of -Mass det. time= 761.6 min ( 1,583.8 - 822.2 )
Volume Invert Avail.Storage Storage Description
#1 634.00' 85,633 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic -feet) (cubic -feet)
634.00 10,132 0 0
636.00 12,767 22,899 22,899
638.00 15,627 28,394 51,293
640.00 18,713 34,340 85,633
Device Routing Invert Outlet Devices
#1 Primary 630.40' 18.0" x 126.0' long Culvert RCP, square edge headwall, Ke= 0.500
Outlet Invert= 617.77' S= 0.1002 7' Cc= 0.900 n= 0.013
#2 Device 1 634.00' Exfiltration
Head (feet) 0.00 1.00 2.00 3.00 4.00 5.00 6.00
Disch. (cfs) 0.000 0.095 0.134 0.172 0.210 0.248 0.286
#3 Device 1 635.50' 6.0" Vert. Orifice/Grate C= 0.600
#4 Device 1 638.00' 2.00' x 3.00' Horiz. Top of Riser Limited to weir flow C= 0.600
#5 Secondary 639.00' 10.0' long x 16.0' breadth Spillway
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Coef. (English) 2.68 2.70 2.70 2.64 2.63 2.64 2.64 2.63
Primary OutFlow Max=3.88 cfs @ 12.52 hrs HW=638.16' (Free Discharge)
L1=Culvert (Passes 3.88 cfs of 22.54 cfs potential flow)
2=Exfltration (Custom Controls 0.22 cfs)
3=Orifice/Grate (Orifice Controls 1.47 cfs @ 7.48 fps)
=Top of Riser (Weir Controls 2.19 cfs @ 1.33 fps)
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=634.00' (Free Discharge)
5=Spillway ( Controls 0.00 cfs)

2020.17-BM P2
Type 11 24-hr 10-yr Concord Rainfall=5.10"
Prepared by {enter your company name here} Page 18
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 8/4/2022
Hydrograph for Pond 3P: (BMP2)
Time
Inflow
Storage
Elevation
Outflow
Primary
Secondary
(hours)
(cfs)
(cubic -feet)
(feet)
(cfs)
(cfs)
(cfs)
0.00
0.00
0
634.00
0.00
0.00
0.00
5.00
0.00
0
634.00
0.00
0.00
0.00
10.00
0.40
1,297
634.13
0.01
0.01
0.00
15.00
1.26
50,810
637.97
1.62
1.62
0.00
20.00
0.56
39,134
637.19
1.31
1.31
0.00
25.00
0.00
26,760
636.30
0.84
0.84
0.00
30.00
0.00
18,484
635.65
0.19
0.19
0.00
35.00
0.00
16,120
635.45
0.11
0.11
0.00
40.00
0.00
14,150
635.29
0.11
0.11
0.00
45.00
0.00
12,293
635.13
0.10
0.10
0.00
50.00
0.00
10,547
634.98
0.09
0.09
0.00
55.00
0.00
8,993
634.84
0.08
0.08
0.00
60.00
0.00
7,659
634.72
0.07
0.07
0.00
65.00
0.00
6,515
634.62
0.06
0.06
0.00
70.00
0.00
5,537
634.53
0.05
0.05
0.00
75.00
0.00
4,701
634.45
0.04
0.04
0.00
80.00
0.00
3,989
634.38
0.04
0.04
0.00
85.00
0.00
3,382
634.33
0.03
0.03
0.00
90.00
0.00
2,867
634.28
0.03
0.03
0.00
95.00
0.00
2,428
634.24
0.02
0.02
0.00
100.00
0.00
2,056
634.20
0.02
0.02
0.00
105.00
0.00
1,740
634.17
0.02
0.02
0.00
110.00
0.00
1,473
634.14
0.01
0.01
0.00
115.00
0.00
1,246
634.12
0.01
0.01
0.00
120.00
0.00
1,054
634.10
0.01
0.01
0.00
125.00
0.00
891
634.09
0.01
0.01
0.00
130.00
0.00
753
634.07
0.01
0.01
0.00
135.00
0.00
637
634.06
0.01
0.01
0.00
140.00
0.00
538
634.05
0.01
0.01
0.00
145.00
0.00
455
634.04
0.00
0.00
0.00
150.00
0.00
385
634.04
0.00
0.00
0.00
155.00
0.00
325
634.03
0.00
0.00
0.00
160.00
0.00
275
634.03
0.00
0.00
0.00
165.00
0.00
232
634.02
0.00
0.00
0.00
170.00
0.00
196
634.02
0.00
0.00
0.00
175.00
0.00
166
634.02
0.00
0.00
0.00
180.00
0.00
140
634.01
0.00
0.00
0.00
185.00
0.00
119
634.01
0.00
0.00
0.00
190.00
0.00
100
634.01
0.00
0.00
0.00
195.00
0.00
85
634.01
0.00
0.00
0.00
200.00
0.00
72
634.01
0.00
0.00
0.00

2020.17-BM P2
Type 11 24-hr 10-yr Concord Rainfall=5.10"
Prepared by {enter your company name here} Page 19
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 8/4/2022
Stage -Discharge for Pond 3P: (BMP2)
Elevation Discharge Primary Secondary
(feet)
(cfs)
(cfs)
(cfs)
634.00
0.00
0.00
0.00
634.10
0.01
0.01
0.00
634.20
0.02
0.02
0.00
634.30
0.03
0.03
0.00
634.40
0.04
0.04
0.00
634.50
0.05
0.05
0.00
634.60
0.06
0.06
0.00
634.70
0.07
0.07
0.00
634.80
0.08
0.08
0.00
634.90
0.09
0.09
0.00
635.00
0.10
0.10
0.00
635.10
0.10
0.10
0.00
635.20
0.10
0.10
0.00
635.30
0.11
0.11
0.00
635.40
0.11
0.11
0.00
635.50
0.11
0.11
0.00
635.60
0.15
0.15
0.00
635.70
0.23
0.23
0.00
635.80
0.36
0.36
0.00
635.90
0.49
0.49
0.00
636.00
0.61
0.61
0.00
636.10
0.70
0.70
0.00
636.20
0.78
0.78
0.00
636.30
0.85
0.85
0.00
636.40
0.91
0.91
0.00
636.50
0.97
0.97
0.00
636.60
1.03
1.03
0.00
636.70
1.08
1.08
0.00
636.80
1.13
1.13
0.00
636.90
1.18
1.18
0.00
637.00
1.23
1.23
0.00
637.10
1.27
1.27
0.00
637.20
1.32
1.32
0.00
637.30
1.36
1.36
0.00
637.40
1.40
1.40
0.00
637.50
1.44
1.44
0.00
637.60
1.48
1.48
0.00
637.70
1.52
1.52
0.00
637.80
1.56
1.56
0.00
637.90
1.59
1.59
0.00
638.00
1.63
1.63
0.00
638.10
2.70
2.70
0.00
638.20
4.62
4.62
0.00
638.30
7.10
7.10
0.00
638.40
10.04
10.04
0.00
638.50
13.36
13.36
0.00
638.60
17.03
17.03
0.00
638.70
21.01
21.01
0.00
638.80
23.53
23.53
0.00
638.90
23.69
23.69
0.00
639.00
23.84
23.84
0.00
639.10
24.84
23.99
0.85
Elevation Discharge Primary Secondary
(feet)
(cfs)
(cfs)
(cfs)
639.20
26.54
24.14
2.40
639.30
28.71
24.29
4.42
639.40
31.27
24.44
6.83
639.50
34.13
24.59
9.55
639.60
37.28
24.73
12.55
639.70
40.52
24.88
15.64
639.80
43.92
25.03
18.89
639.90
47.67
25.17
22.50
640.00
51.61
25.31
26.30

2020.17-BM P2
Type // 24-hr 10-yr Concord Rainfall=5.10"
Prepared by {enter your company name here} Page 20
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 8/4/2022
Stage -Area -Storage for Pond 3P: (BMP2)
Elevation
Surface
Storage
(feet)
(sq-ft)
(cubic -feet)
634.00
10,132
0
634.10
10,264
1,020
634.20
10,396
2,053
634.30
10,527
3,099
634.40
10,659
4,158
634.50
10,791
5,231
634.60
10,923
6,316
634.70
11,054
7,415
634.80
11,186
8,527
634.90
11,318
9,652
635.00
11,450
10,791
635.10
11,581
11,942
635.20
11,713
13,107
635.30
11,845
14,285
635.40
11,976
15,476
635.50
12,108
16,680
635.60
12,240
17,898
635.70
12,372
19,128
635.80
12,503
20,372
635.90
12,635
21,629
636.00
12,767
22,899
636.10
12,910
24,183
636.20
13,053
25,481
636.30
13,196
26,793
636.40
13,339
28,120
636.50
13,482
29,461
636.60
13,625
30,817
636.70
13,768
32,186
636.80
13,911
33,570
636.90
14,054
34,968
637.00
14,197
36,381
637.10
14,340
37,808
637.20
14,483
39,249
637.30
14,626
40,704
637.40
14,769
42,174
637.50
14,912
43,658
637.60
15,055
45,157
637.70
15,198
46,669
637.80
15,341
48,196
637.90
15,484
49,737
638.00
15,627
51,293
638.10
15,781
52,863
638.20
15,936
54,449
638.30
16,090
56,051
638.40
16,244
57,667
638.50
16,399
59,299
638.60
16,553
60,947
638.70
16,707
62,610
638.80
16,861
64,288
638.90
17,016
65,982
639.00
17,170
67,692
639.10
17,324
69,416
Elevation
Surface
Storage
(feet)
(sq-ft)
(cubic -feet)
639.20
17,479
71,156
639.30
17,633
72,912
639.40
17,787
74,683
639.50
17,942
76,469
639.60
18,096
78,271
639.70
18,250
80,089
639.80
18,404
81,921
639.90
18,559
83,769
640.00
18,713
85,633

2020.17-BM P2 Type/1 24-hr 25-yr Concord Rainfall=6.00"
Prepared by {enter your company name here} Page 21
HvdroCAD® 8.00 s/n 004317 © 2006 HvdroCAD Software Solutions LLC 8/4/2022
Time span=0.00-200.00 hrs, dt=0.01 hrs, 20001 points
Runoff by SCS TR-20 method, UH=SCS
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment 1S: (Predeveloped) Runoff Area=9.800 ac Runoff Depth=3.18"
Flow Length=729' Tc=15.7 min CN=74 Runoff=39.54 cfs 2.601 of
Subcatchment 2S: (Post Developed) Runoff Area=9.800 ac Runoff Depth=3.58"
Tc=5.0 min CN=78 Runoff=63.96 cfs 2.923 of
Pond 3P: (BMP2) Peak Elev=638.58' Storage=60,690 cf Inflow=63.96 cfs 2.923 of
Primary=16.45 cfs 2.921 of Secondary=0.00 cfs 0.000 of Outflow=16.45 cfs 2.921 of
Total Runoff Area = 19.600 ac Runoff Volume = 5.524 of Average Runoff Depth = 3.38"
100.00% Pervious Area = 19.600 ac 0.00% Impervious Area = 0.000 ac

2020.17-BM P2 Type/1 24-hr 25-yr Concord Rainfall=6.00"
Prepared by {enter your company name here} Page 22
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 8/4/2022
Subcatchment 1S: (Predeveloped)
BASED ON EXISTING CONDITIONS
Runoff = 39.54 cfs @ 12.08 hrs, Volume= 2.601 af, Depth= 3.18"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Type II 24-hr 25-yr Concord Rainfall=6.00"
Area (ac) CN Description
3.090
73
Woods, Fair, HSG C
3.430
79
Pasture/grassland/range, Fair, HSG C
3.280
69
Pasture/grassland/range, Fair, HSG B
9.800
74
Weighted Average
9.800
Pervious Area
Tc
Length
Slope
Velocity
Capacity Description
(min)
(feet)
(ft/ft)
(ft/sec)
(cfs)
8.9
100
0.0586
0.19
Sheet Flow,
Grass: Dense n= 0.240 P2= 3.50"
6.8
629
0.0482
1.54
Shallow Concentrated Flow,
Short Grass Pasture Kv= 7.0 fps
15.7 729 Total

2020.17-BM P2
Type // 24-hr 25-yr Concord Rainfall=6.00"
Prepared by {enter your company name here} Page 23
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 8/4/2022
Hydrograph for Subcatchment 1S: (Predeveloped)
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
0.00
0.00
0.00
0.00
2.00
0.13
0.00
0.00
4.00
0.29
0.00
0.00
6.00
0.48
0.00
0.00
8.00
0.72
0.00
0.00
10.00
1.09
0.04
0.35
12.00
3.98
1.58
31.80
14.00
4.92
2.30
1.96
16.00
5.28
2.59
1.19
18.00
5.53
2.79
0.91
20.00
5.71
2.94
0.67
22.00
5.86
3.07
0.60
24.00
6.00
3.18
0.55
26.00
6.00
3.18
0.00
28.00
6.00
3.18
0.00
30.00
6.00
3.18
0.00
32.00
6.00
3.18
0.00
34.00
6.00
3.18
0.00
36.00
6.00
3.18
0.00
38.00
6.00
3.18
0.00
40.00
6.00
3.18
0.00
42.00
6.00
3.18
0.00
44.00
6.00
3.18
0.00
46.00
6.00
3.18
0.00
48.00
6.00
3.18
0.00
50.00
6.00
3.18
0.00
52.00
6.00
3.18
0.00
54.00
6.00
3.18
0.00
56.00
6.00
3.18
0.00
58.00
6.00
3.18
0.00
60.00
6.00
3.18
0.00
62.00
6.00
3.18
0.00
64.00
6.00
3.18
0.00
66.00
6.00
3.18
0.00
68.00
6.00
3.18
0.00
70.00
6.00
3.18
0.00
72.00
6.00
3.18
0.00
74.00
6.00
3.18
0.00
76.00
6.00
3.18
0.00
78.00
6.00
3.18
0.00
80.00
6.00
3.18
0.00
82.00
6.00
3.18
0.00
84.00
6.00
3.18
0.00
86.00
6.00
3.18
0.00
88.00
6.00
3.18
0.00
90.00
6.00
3.18
0.00
92.00
6.00
3.18
0.00
94.00
6.00
3.18
0.00
96.00
6.00
3.18
0.00
98.00
6.00
3.18
0.00
100.00
6.00
3.18
0.00
102.00
6.00
3.18
0.00
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
104.00
6.00
3.18
0.00
106.00
6.00
3.18
0.00
108.00
6.00
3.18
0.00
110.00
6.00
3.18
0.00
112.00
6.00
3.18
0.00
114.00
6.00
3.18
0.00
116.00
6.00
3.18
0.00
118.00
6.00
3.18
0.00
120.00
6.00
3.18
0.00
122.00
6.00
3.18
0.00
124.00
6.00
3.18
0.00
126.00
6.00
3.18
0.00
128.00
6.00
3.18
0.00
130.00
6.00
3.18
0.00
132.00
6.00
3.18
0.00
134.00
6.00
3.18
0.00
136.00
6.00
3.18
0.00
138.00
6.00
3.18
0.00
140.00
6.00
3.18
0.00
142.00
6.00
3.18
0.00
144.00
6.00
3.18
0.00
146.00
6.00
3.18
0.00
148.00
6.00
3.18
0.00
150.00
6.00
3.18
0.00
152.00
6.00
3.18
0.00
154.00
6.00
3.18
0.00
156.00
6.00
3.18
0.00
158.00
6.00
3.18
0.00
160.00
6.00
3.18
0.00
162.00
6.00
3.18
0.00
164.00
6.00
3.18
0.00
166.00
6.00
3.18
0.00
168.00
6.00
3.18
0.00
170.00
6.00
3.18
0.00
172.00
6.00
3.18
0.00
174.00
6.00
3.18
0.00
176.00
6.00
3.18
0.00
178.00
6.00
3.18
0.00
180.00
6.00
3.18
0.00
182.00
6.00
3.18
0.00
184.00
6.00
3.18
0.00
186.00
6.00
3.18
0.00
188.00
6.00
3.18
0.00
190.00
6.00
3.18
0.00
192.00
6.00
3.18
0.00
194.00
6.00
3.18
0.00
196.00
6.00
3.18
0.00
198.00
6.00
3.18
0.00
200.00
6.00
3.18
0.00

2020.17-BM P2 Type/1 24-hr 25-yr Concord Rainfall=6.00"
Prepared by {enter your company name here} Page 24
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 8/4/2022
Subcatchment 2S: (Post Developed)
Runoff = 63.96 cfs @ 11.96 hrs, Volume= 2.923 af, Depth= 3.58"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Type II 24-hr 25-yr Concord Rainfall=6.00"
Area (ac) CN
Description
3.280 83
RM-2 (C)
6.520 75
RM-2 (B)
9.800 78
Weighted Average
9.800
Pervious Area
Tc Length
Slope Velocity Capacity Description
(min) (feet)
(ft/ft) (ft/sec) (cfs)
5.0
Direct Entry,

2020.17-BM P2
Type // 24-hr 25-yr Concord Rainfall=6.00"
Prepared by {enter your company name here} Page 25
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 8/4/2022
Hydrograph for Subcatchment 2S: (Post Developed)
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
0.00
0.00
0.00
0.00
2.00
0.13
0.00
0.00
4.00
0.29
0.00
0.00
6.00
0.48
0.00
0.00
8.00
0.72
0.01
0.12
10.00
1.09
0.08
0.64
12.00
3.98
1.87
54.49
14.00
4.92
2.64
1.93
16.00
5.28
2.95
1.20
18.00
5.53
3.16
0.94
20.00
5.71
3.33
0.68
22.00
5.86
3.46
0.63
24.00
6.00
3.58
0.58
26.00
6.00
3.58
0.00
28.00
6.00
3.58
0.00
30.00
6.00
3.58
0.00
32.00
6.00
3.58
0.00
34.00
6.00
3.58
0.00
36.00
6.00
3.58
0.00
38.00
6.00
3.58
0.00
40.00
6.00
3.58
0.00
42.00
6.00
3.58
0.00
44.00
6.00
3.58
0.00
46.00
6.00
3.58
0.00
48.00
6.00
3.58
0.00
50.00
6.00
3.58
0.00
52.00
6.00
3.58
0.00
54.00
6.00
3.58
0.00
56.00
6.00
3.58
0.00
58.00
6.00
3.58
0.00
60.00
6.00
3.58
0.00
62.00
6.00
3.58
0.00
64.00
6.00
3.58
0.00
66.00
6.00
3.58
0.00
68.00
6.00
3.58
0.00
70.00
6.00
3.58
0.00
72.00
6.00
3.58
0.00
74.00
6.00
3.58
0.00
76.00
6.00
3.58
0.00
78.00
6.00
3.58
0.00
80.00
6.00
3.58
0.00
82.00
6.00
3.58
0.00
84.00
6.00
3.58
0.00
86.00
6.00
3.58
0.00
88.00
6.00
3.58
0.00
90.00
6.00
3.58
0.00
92.00
6.00
3.58
0.00
94.00
6.00
3.58
0.00
96.00
6.00
3.58
0.00
98.00
6.00
3.58
0.00
100.00
6.00
3.58
0.00
102.00
6.00
3.58
0.00
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
104.00
6.00
3.58
0.00
106.00
6.00
3.58
0.00
108.00
6.00
3.58
0.00
110.00
6.00
3.58
0.00
112.00
6.00
3.58
0.00
114.00
6.00
3.58
0.00
116.00
6.00
3.58
0.00
118.00
6.00
3.58
0.00
120.00
6.00
3.58
0.00
122.00
6.00
3.58
0.00
124.00
6.00
3.58
0.00
126.00
6.00
3.58
0.00
128.00
6.00
3.58
0.00
130.00
6.00
3.58
0.00
132.00
6.00
3.58
0.00
134.00
6.00
3.58
0.00
136.00
6.00
3.58
0.00
138.00
6.00
3.58
0.00
140.00
6.00
3.58
0.00
142.00
6.00
3.58
0.00
144.00
6.00
3.58
0.00
146.00
6.00
3.58
0.00
148.00
6.00
3.58
0.00
150.00
6.00
3.58
0.00
152.00
6.00
3.58
0.00
154.00
6.00
3.58
0.00
156.00
6.00
3.58
0.00
158.00
6.00
3.58
0.00
160.00
6.00
3.58
0.00
162.00
6.00
3.58
0.00
164.00
6.00
3.58
0.00
166.00
6.00
3.58
0.00
168.00
6.00
3.58
0.00
170.00
6.00
3.58
0.00
172.00
6.00
3.58
0.00
174.00
6.00
3.58
0.00
176.00
6.00
3.58
0.00
178.00
6.00
3.58
0.00
180.00
6.00
3.58
0.00
182.00
6.00
3.58
0.00
184.00
6.00
3.58
0.00
186.00
6.00
3.58
0.00
188.00
6.00
3.58
0.00
190.00
6.00
3.58
0.00
192.00
6.00
3.58
0.00
194.00
6.00
3.58
0.00
196.00
6.00
3.58
0.00
198.00
6.00
3.58
0.00
200.00
6.00
3.58
0.00

2020.17-BM P2 Type/1 24-hr 25-yr Concord Rainfall=6.00"
Prepared by {enter your company name here} Page 26
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 8/4/2022
Pond 3P: (BMP2)
Inflow Area = 9.800 ac, Inflow Depth = 3.58" for 25-yr Concord event
Inflow =
63.96 cfs @
11.96 hrs,
Volume=
2.923 of
Outflow =
16.45 cfs @
12.09 hrs,
Volume=
2.921 af, Atten= 74%, Lag= 7.5 min
Primary =
16.45 cfs @
12.09 hrs,
Volume=
2.921 of
Secondary =
0.00 cfs @
0.00 hrs,
Volume=
0.000 of
Routing by Stor-Ind method, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Peak Elev= 638.58' @ 12.09 hrs Surf.Area= 16,529 sf Storage= 60,690 cf
Plug -Flow detention time= 625.2 min calculated for 2.921 of (100% of inflow)
Center -of -Mass det. time= 624.9 min ( 1,440.0 - 815.1 )
Volume Invert Avail.Storage Storage Description
#1 634.00' 85,633 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic -feet) (cubic -feet)
634.00 10,132 0 0
636.00 12,767 22,899 22,899
638.00 15,627 28,394 51,293
640.00 18,713 34,340 85,633
Device Routing Invert Outlet Devices
#1 Primary 630.40' 18.0" x 126.0' long Culvert RCP, square edge headwall, Ke= 0.500
Outlet Invert= 617.77' S= 0.1002 7' Cc= 0.900 n= 0.013
#2 Device 1 634.00' Exfiltration
Head (feet) 0.00 1.00 2.00 3.00 4.00 5.00 6.00
Disch. (cfs) 0.000 0.095 0.134 0.172 0.210 0.248 0.286
#3 Device 1 635.50' 6.0" Vert. Orifice/Grate C= 0.600
#4 Device 1 638.00' 2.00' x 3.00' Horiz. Top of Riser Limited to weir flow C= 0.600
#5 Secondary 639.00' 10.0' long x 16.0' breadth Spillway
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Coef. (English) 2.68 2.70 2.70 2.64 2.63 2.64 2.64 2.63
Primary OutFlow Max=16.42 cfs @ 12.09 hrs HW=638.58' (Free Discharge)
L1=Culvert (Passes 16.42 cfs of 23.20 cfs potential flow)
2=Exfltration (Custom Controls 0.23 cfs)
3=Orifice/Grate (Orifice Controls 1.59 cfs @ 8.11 fps)
=Top of Riser (Weir Controls 14.59 cfs @ 2.50 fps)
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=634.00' (Free Discharge)
5=Spillway ( Controls 0.00 cfs)

2020.17-BM P2
Type // 24-hr 25-yr Concord Rainfall=6.00"
Prepared by {enter your company name here} Page 27
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 8/4/2022
Hydrograph for Pond 3P: (BMP2)
Time
Inflow
Storage
Elevation
Outflow
Primary
Secondary
(hours)
(cfs)
(cubic -feet)
(feet)
(cfs)
(cfs)
(cfs)
0.00
0.00
0
634.00
0.00
0.00
0.00
5.00
0.00
0
634.00
0.00
0.00
0.00
10.00
0.64
2,635
634.26
0.02
0.02
0.00
15.00
1.54
51,561
638.02
1.71
1.71
0.00
20.00
0.68
42,196
637.40
1.40
1.40
0.00
25.00
0.00
29,493
636.50
0.97
0.97
0.00
30.00
0.00
19,107
635.70
0.23
0.23
0.00
35.00
0.00
16,460
635.48
0.11
0.11
0.00
40.00
0.00
14,471
635.32
0.11
0.11
0.00
45.00
0.00
12,596
635.16
0.10
0.10
0.00
50.00
0.00
10,830
635.00
0.10
0.10
0.00
55.00
0.00
9,237
634.86
0.08
0.08
0.00
60.00
0.00
7,868
634.74
0.07
0.07
0.00
65.00
0.00
6,694
634.63
0.06
0.06
0.00
70.00
0.00
5,690
634.54
0.05
0.05
0.00
75.00
0.00
4,832
634.46
0.04
0.04
0.00
80.00
0.00
4,100
634.39
0.04
0.04
0.00
85.00
0.00
3,477
634.34
0.03
0.03
0.00
90.00
0.00
2,947
634.29
0.03
0.03
0.00
95.00
0.00
2,496
634.24
0.02
0.02
0.00
100.00
0.00
2,114
634.21
0.02
0.02
0.00
105.00
0.00
1,789
634.17
0.02
0.02
0.00
110.00
0.00
1,514
634.15
0.01
0.01
0.00
115.00
0.00
1,281
634.13
0.01
0.01
0.00
120.00
0.00
1,083
634.11
0.01
0.01
0.00
125.00
0.00
916
634.09
0.01
0.01
0.00
130.00
0.00
775
634.08
0.01
0.01
0.00
135.00
0.00
655
634.06
0.01
0.01
0.00
140.00
0.00
554
634.05
0.01
0.01
0.00
145.00
0.00
468
634.05
0.00
0.00
0.00
150.00
0.00
396
634.04
0.00
0.00
0.00
155.00
0.00
334
634.03
0.00
0.00
0.00
160.00
0.00
283
634.03
0.00
0.00
0.00
165.00
0.00
239
634.02
0.00
0.00
0.00
170.00
0.00
202
634.02
0.00
0.00
0.00
175.00
0.00
171
634.02
0.00
0.00
0.00
180.00
0.00
144
634.01
0.00
0.00
0.00
185.00
0.00
122
634.01
0.00
0.00
0.00
190.00
0.00
103
634.01
0.00
0.00
0.00
195.00
0.00
87
634.01
0.00
0.00
0.00
200.00
0.00
74
634.01
0.00
0.00
0.00

2020.17-BM P2
Type // 24-hr 25-yr Concord Rainfall=6.00"
Prepared by {enter your company name here} Page 28
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 8/4/2022
Stage -Discharge for Pond 3P: (BMP2)
Elevation Discharge Primary Secondary
(feet)
(cfs)
(cfs)
(cfs)
634.00
0.00
0.00
0.00
634.10
0.01
0.01
0.00
634.20
0.02
0.02
0.00
634.30
0.03
0.03
0.00
634.40
0.04
0.04
0.00
634.50
0.05
0.05
0.00
634.60
0.06
0.06
0.00
634.70
0.07
0.07
0.00
634.80
0.08
0.08
0.00
634.90
0.09
0.09
0.00
635.00
0.10
0.10
0.00
635.10
0.10
0.10
0.00
635.20
0.10
0.10
0.00
635.30
0.11
0.11
0.00
635.40
0.11
0.11
0.00
635.50
0.11
0.11
0.00
635.60
0.15
0.15
0.00
635.70
0.23
0.23
0.00
635.80
0.36
0.36
0.00
635.90
0.49
0.49
0.00
636.00
0.61
0.61
0.00
636.10
0.70
0.70
0.00
636.20
0.78
0.78
0.00
636.30
0.85
0.85
0.00
636.40
0.91
0.91
0.00
636.50
0.97
0.97
0.00
636.60
1.03
1.03
0.00
636.70
1.08
1.08
0.00
636.80
1.13
1.13
0.00
636.90
1.18
1.18
0.00
637.00
1.23
1.23
0.00
637.10
1.27
1.27
0.00
637.20
1.32
1.32
0.00
637.30
1.36
1.36
0.00
637.40
1.40
1.40
0.00
637.50
1.44
1.44
0.00
637.60
1.48
1.48
0.00
637.70
1.52
1.52
0.00
637.80
1.56
1.56
0.00
637.90
1.59
1.59
0.00
638.00
1.63
1.63
0.00
638.10
2.70
2.70
0.00
638.20
4.62
4.62
0.00
638.30
7.10
7.10
0.00
638.40
10.04
10.04
0.00
638.50
13.36
13.36
0.00
638.60
17.03
17.03
0.00
638.70
21.01
21.01
0.00
638.80
23.53
23.53
0.00
638.90
23.69
23.69
0.00
639.00
23.84
23.84
0.00
639.10
24.84
23.99
0.85
Elevation Discharge Primary Secondary
(feet)
(cfs)
(cfs)
(cfs)
639.20
26.54
24.14
2.40
639.30
28.71
24.29
4.42
639.40
31.27
24.44
6.83
639.50
34.13
24.59
9.55
639.60
37.28
24.73
12.55
639.70
40.52
24.88
15.64
639.80
43.92
25.03
18.89
639.90
47.67
25.17
22.50
640.00
51.61
25.31
26.30

2020.17-BM P2
Type // 24-hr 25-yr Concord Rainfall=6.00"
Prepared by {enter your company name here} Page 29
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 8/4/2022
Stage -Area -Storage for Pond 3P: (BMP2)
Elevation
Surface
Storage
(feet)
(sq-ft)
(cubic -feet)
634.00
10,132
0
634.10
10,264
1,020
634.20
10,396
2,053
634.30
10,527
3,099
634.40
10,659
4,158
634.50
10,791
5,231
634.60
10,923
6,316
634.70
11,054
7,415
634.80
11,186
8,527
634.90
11,318
9,652
635.00
11,450
10,791
635.10
11,581
11,942
635.20
11,713
13,107
635.30
11,845
14,285
635.40
11,976
15,476
635.50
12,108
16,680
635.60
12,240
17,898
635.70
12,372
19,128
635.80
12,503
20,372
635.90
12,635
21,629
636.00
12,767
22,899
636.10
12,910
24,183
636.20
13,053
25,481
636.30
13,196
26,793
636.40
13,339
28,120
636.50
13,482
29,461
636.60
13,625
30,817
636.70
13,768
32,186
636.80
13,911
33,570
636.90
14,054
34,968
637.00
14,197
36,381
637.10
14,340
37,808
637.20
14,483
39,249
637.30
14,626
40,704
637.40
14,769
42,174
637.50
14,912
43,658
637.60
15,055
45,157
637.70
15,198
46,669
637.80
15,341
48,196
637.90
15,484
49,737
638.00
15,627
51,293
638.10
15,781
52,863
638.20
15,936
54,449
638.30
16,090
56,051
638.40
16,244
57,667
638.50
16,399
59,299
638.60
16,553
60,947
638.70
16,707
62,610
638.80
16,861
64,288
638.90
17,016
65,982
639.00
17,170
67,692
639.10
17,324
69,416
Elevation
Surface
Storage
(feet)
(sq-ft)
(cubic -feet)
639.20
17,479
71,156
639.30
17,633
72,912
639.40
17,787
74,683
639.50
17,942
76,469
639.60
18,096
78,271
639.70
18,250
80,089
639.80
18,404
81,921
639.90
18,559
83,769
640.00
18,713
85,633

2020.17-BM P2 Type 11 24-hr 50-yr Concord Rainfall=6.80"
Prepared by {enter your company name here} Page 30
HvdroCAD® 8.00 s/n 004317 © 2006 HvdroCAD Software Solutions LLC 8/4/2022
Time span=0.00-200.00 hrs, dt=0.01 hrs, 20001 points
Runoff by SCS TR-20 method, UH=SCS
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment 1S: (Predeveloped) Runoff Area=9.800 ac Runoff Depth=3.87"
Flow Length=729' Tc=15.7 min CN=74 Runoff=47.97 cfs 3.159 of
Subcatchment 2S: (Post Developed) Runoff Area=9.800 ac Runoff Depth=4.29"
Tc=5.0 min CN=78 Runoff=76.09 cfs 3.507 of
Pond 3P: (BMP2) Peak Elev=639.11' Storage=69,523 cf Inflow=76.09 cfs 3.507 of
Primary=24.00 cfs 3.500 of Secondary=0.94 cfs 0.005 of Outflow=24.94 cfs 3.505 of
Total Runoff Area = 19.600 ac Runoff Volume = 6.666 of Average Runoff Depth = 4.08"
100.00% Pervious Area = 19.600 ac 0.00% Impervious Area = 0.000 ac

2020.17-BM P2 Type 11 24-hr 50-yr Concord Rainfall=6.80"
Prepared by {enter your company name here} Page 31
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 8/4/2022
Subcatchment 1S: (Predeveloped)
BASED ON EXISTING CONDITIONS
Runoff = 47.97 cfs @ 12.08 hrs, Volume= 3.159 af, Depth= 3.87"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Type II 24-hr 50-yr Concord Rainfall=6.80"
Area (ac) CN Description
3.090
73
Woods, Fair, HSG C
3.430
79
Pasture/grassland/range, Fair, HSG C
3.280
69
Pasture/grassland/range, Fair, HSG B
9.800
74
Weighted Average
9.800
Pervious Area
Tc
Length
Slope
Velocity
Capacity Description
(min)
(feet)
(ft/ft)
(ft/sec)
(cfs)
8.9
100
0.0586
0.19
Sheet Flow,
Grass: Dense n= 0.240 P2= 3.50"
6.8
629
0.0482
1.54
Shallow Concentrated Flow,
Short Grass Pasture Kv= 7.0 fps
15.7 729 Total

2020.17-BM P2
Type // 24-hr 50-yr Concord Rainfall=6.80"
Prepared by {enter your company name here} Page 32
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 8/4/2022
Hydrograph for Subcatchment 1S: (Predeveloped)
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
0.00
0.00
0.00
0.00
2.00
0.15
0.00
0.00
4.00
0.33
0.00
0.00
6.00
0.54
0.00
0.00
8.00
0.82
0.00
0.06
10.00
1.23
0.07
0.54
12.00
4.51
1.98
38.98
14.00
5.58
2.83
2.31
16.00
5.98
3.17
1.39
18.00
6.26
3.41
1.06
20.00
6.47
3.59
0.78
22.00
6.64
3.73
0.70
24.00
6.80
3.87
0.65
26.00
6.80
3.87
0.00
28.00
6.80
3.87
0.00
30.00
6.80
3.87
0.00
32.00
6.80
3.87
0.00
34.00
6.80
3.87
0.00
36.00
6.80
3.87
0.00
38.00
6.80
3.87
0.00
40.00
6.80
3.87
0.00
42.00
6.80
3.87
0.00
44.00
6.80
3.87
0.00
46.00
6.80
3.87
0.00
48.00
6.80
3.87
0.00
50.00
6.80
3.87
0.00
52.00
6.80
3.87
0.00
54.00
6.80
3.87
0.00
56.00
6.80
3.87
0.00
58.00
6.80
3.87
0.00
60.00
6.80
3.87
0.00
62.00
6.80
3.87
0.00
64.00
6.80
3.87
0.00
66.00
6.80
3.87
0.00
68.00
6.80
3.87
0.00
70.00
6.80
3.87
0.00
72.00
6.80
3.87
0.00
74.00
6.80
3.87
0.00
76.00
6.80
3.87
0.00
78.00
6.80
3.87
0.00
80.00
6.80
3.87
0.00
82.00
6.80
3.87
0.00
84.00
6.80
3.87
0.00
86.00
6.80
3.87
0.00
88.00
6.80
3.87
0.00
90.00
6.80
3.87
0.00
92.00
6.80
3.87
0.00
94.00
6.80
3.87
0.00
96.00
6.80
3.87
0.00
98.00
6.80
3.87
0.00
100.00
6.80
3.87
0.00
102.00
6.80
3.87
0.00
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
104.00
6.80
3.87
0.00
106.00
6.80
3.87
0.00
108.00
6.80
3.87
0.00
110.00
6.80
3.87
0.00
112.00
6.80
3.87
0.00
114.00
6.80
3.87
0.00
116.00
6.80
3.87
0.00
118.00
6.80
3.87
0.00
120.00
6.80
3.87
0.00
122.00
6.80
3.87
0.00
124.00
6.80
3.87
0.00
126.00
6.80
3.87
0.00
128.00
6.80
3.87
0.00
130.00
6.80
3.87
0.00
132.00
6.80
3.87
0.00
134.00
6.80
3.87
0.00
136.00
6.80
3.87
0.00
138.00
6.80
3.87
0.00
140.00
6.80
3.87
0.00
142.00
6.80
3.87
0.00
144.00
6.80
3.87
0.00
146.00
6.80
3.87
0.00
148.00
6.80
3.87
0.00
150.00
6.80
3.87
0.00
152.00
6.80
3.87
0.00
154.00
6.80
3.87
0.00
156.00
6.80
3.87
0.00
158.00
6.80
3.87
0.00
160.00
6.80
3.87
0.00
162.00
6.80
3.87
0.00
164.00
6.80
3.87
0.00
166.00
6.80
3.87
0.00
168.00
6.80
3.87
0.00
170.00
6.80
3.87
0.00
172.00
6.80
3.87
0.00
174.00
6.80
3.87
0.00
176.00
6.80
3.87
0.00
178.00
6.80
3.87
0.00
180.00
6.80
3.87
0.00
182.00
6.80
3.87
0.00
184.00
6.80
3.87
0.00
186.00
6.80
3.87
0.00
188.00
6.80
3.87
0.00
190.00
6.80
3.87
0.00
192.00
6.80
3.87
0.00
194.00
6.80
3.87
0.00
196.00
6.80
3.87
0.00
198.00
6.80
3.87
0.00
200.00
6.80
3.87
0.00

2020.17-BM P2 Type 11 24-hr 50-yr Concord Rainfall=6.80"
Prepared by {enter your company name here} Page 33
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 8/4/2022
Subcatchment 2S: (Post Developed)
Runoff = 76.09 cfs @ 11.96 hrs, Volume= 3.507 af, Depth= 4.29"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Type II 24-hr 50-yr Concord Rainfall=6.80"
Area (ac) CN
Description
3.280 83
RM-2 (C)
6.520 75
RM-2 (B)
9.800 78
Weighted Average
9.800
Pervious Area
Tc Length
Slope Velocity Capacity Description
(min) (feet)
(ft/ft) (ft/sec) (cfs)
5.0
Direct Entry,

2020.17-BM P2
Type // 24-hr 50-yr Concord Rainfall=6.80"
Prepared by {enter your company name here} Page 34
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 8/4/2022
Hydrograph for Subcatchment 2S: (Post Developed)
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
0.00
0.00
0.00
0.00
2.00
0.15
0.00
0.00
4.00
0.33
0.00
0.00
6.00
0.54
0.00
0.00
8.00
0.82
0.02
0.22
10.00
1.23
0.13
0.88
12.00
4.51
2.30
64.55
14.00
5.58
3.21
2.25
16.00
5.98
3.56
1.40
18.00
6.26
3.81
1.09
20.00
6.47
4.00
0.79
22.00
6.64
4.15
0.73
24.00
6.80
4.29
0.67
26.00
6.80
4.29
0.00
28.00
6.80
4.29
0.00
30.00
6.80
4.29
0.00
32.00
6.80
4.29
0.00
34.00
6.80
4.29
0.00
36.00
6.80
4.29
0.00
38.00
6.80
4.29
0.00
40.00
6.80
4.29
0.00
42.00
6.80
4.29
0.00
44.00
6.80
4.29
0.00
46.00
6.80
4.29
0.00
48.00
6.80
4.29
0.00
50.00
6.80
4.29
0.00
52.00
6.80
4.29
0.00
54.00
6.80
4.29
0.00
56.00
6.80
4.29
0.00
58.00
6.80
4.29
0.00
60.00
6.80
4.29
0.00
62.00
6.80
4.29
0.00
64.00
6.80
4.29
0.00
66.00
6.80
4.29
0.00
68.00
6.80
4.29
0.00
70.00
6.80
4.29
0.00
72.00
6.80
4.29
0.00
74.00
6.80
4.29
0.00
76.00
6.80
4.29
0.00
78.00
6.80
4.29
0.00
80.00
6.80
4.29
0.00
82.00
6.80
4.29
0.00
84.00
6.80
4.29
0.00
86.00
6.80
4.29
0.00
88.00
6.80
4.29
0.00
90.00
6.80
4.29
0.00
92.00
6.80
4.29
0.00
94.00
6.80
4.29
0.00
96.00
6.80
4.29
0.00
98.00
6.80
4.29
0.00
100.00
6.80
4.29
0.00
102.00
6.80
4.29
0.00
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
104.00
6.80
4.29
0.00
106.00
6.80
4.29
0.00
108.00
6.80
4.29
0.00
110.00
6.80
4.29
0.00
112.00
6.80
4.29
0.00
114.00
6.80
4.29
0.00
116.00
6.80
4.29
0.00
118.00
6.80
4.29
0.00
120.00
6.80
4.29
0.00
122.00
6.80
4.29
0.00
124.00
6.80
4.29
0.00
126.00
6.80
4.29
0.00
128.00
6.80
4.29
0.00
130.00
6.80
4.29
0.00
132.00
6.80
4.29
0.00
134.00
6.80
4.29
0.00
136.00
6.80
4.29
0.00
138.00
6.80
4.29
0.00
140.00
6.80
4.29
0.00
142.00
6.80
4.29
0.00
144.00
6.80
4.29
0.00
146.00
6.80
4.29
0.00
148.00
6.80
4.29
0.00
150.00
6.80
4.29
0.00
152.00
6.80
4.29
0.00
154.00
6.80
4.29
0.00
156.00
6.80
4.29
0.00
158.00
6.80
4.29
0.00
160.00
6.80
4.29
0.00
162.00
6.80
4.29
0.00
164.00
6.80
4.29
0.00
166.00
6.80
4.29
0.00
168.00
6.80
4.29
0.00
170.00
6.80
4.29
0.00
172.00
6.80
4.29
0.00
174.00
6.80
4.29
0.00
176.00
6.80
4.29
0.00
178.00
6.80
4.29
0.00
180.00
6.80
4.29
0.00
182.00
6.80
4.29
0.00
184.00
6.80
4.29
0.00
186.00
6.80
4.29
0.00
188.00
6.80
4.29
0.00
190.00
6.80
4.29
0.00
192.00
6.80
4.29
0.00
194.00
6.80
4.29
0.00
196.00
6.80
4.29
0.00
198.00
6.80
4.29
0.00
200.00
6.80
4.29
0.00

2020.17-BM P2 Type 11 24-hr 50-yr Concord Rainfall=6.80"
Prepared by {enter your company name here} Page 35
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 8/4/2022
Pond 3P: (BMP2)
Inflow Area = 9.800 ac, Inflow Depth = 4.29" for 50-yr Concord event
Inflow =
76.09 cfs @
11.96 hrs,
Volume=
3.507 of
Outflow =
24.94 cfs @
12.07 hrs,
Volume=
3.505 af, Atten= 67%, Lag= 6.5 min
Primary =
24.00 cfs @
12.07 hrs,
Volume=
3.500 of
Secondary =
0.94 cfs @
12.07 hrs,
Volume=
0.005 of
Routing by Stor-Ind method, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Peak Elev= 639.11' @ 12.07 hrs Surf.Area= 17,334 sf Storage= 69,523 cf
Plug -Flow detention time= 540.7 min calculated for 3.505 of (100% of inflow)
Center -of -Mass det. time= 540.9 min ( 1,350.8 - 810.0 )
Volume Invert Avail.Storage Storage Description
#1 634.00' 85,633 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic -feet) (cubic -feet)
634.00 10,132 0 0
636.00 12,767 22,899 22,899
638.00 15,627 28,394 51,293
640.00 18,713 34,340 85,633
Device Routing Invert Outlet Devices
#1 Primary 630.40' 18.0" x 126.0' long Culvert RCP, square edge headwall, Ke= 0.500
Outlet Invert= 617.77' S= 0.1002 7' Cc= 0.900 n= 0.013
#2 Device 1 634.00' Exfiltration
Head (feet) 0.00 1.00 2.00 3.00 4.00 5.00 6.00
Disch. (cfs) 0.000 0.095 0.134 0.172 0.210 0.248 0.286
#3 Device 1 635.50' 6.0" Vert. Orifice/Grate C= 0.600
#4 Device 1 638.00' 2.00' x 3.00' Horiz. Top of Riser Limited to weir flow C= 0.600
#5 Secondary 639.00' 10.0' long x 16.0' breadth Spillway
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Coef. (English) 2.68 2.70 2.70 2.64 2.63 2.64 2.64 2.63
Primary OutFlow Max=24.00 cfs @ 12.07 hrs HW=639.11' (Free Discharge)
L1=Culvert (Inlet Controls 24.00 cfs @ 13.58 fps)
2=Exfltration (Passes < 0.25 cfs potential flow)
3=Orifice/Grate (Passes < 1.73 cfs potential flow)
=Top of Riser (Passes < 30.38 cfs potential flow)
Secondary OutFlow Max=0.92 cfs @ 12.07 hrs HW=639.11' (Free Discharge)
5=Spillway (Weir Controls 0.92 cfs @ 0.87 fps)

2020.17-BM P2
Type // 24-hr 50-yr Concord Rainfall=6.80"
Prepared by {enter your company name here} Page 36
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 8/4/2022
Hydrograph for Pond 3P: (BMP2)
Time
Inflow
Storage
Elevation
Outflow
Primary
Secondary
(hours)
(cfs)
(cubic -feet)
(feet)
(cfs)
(cfs)
(cfs)
0.00
0.00
0
634.00
0.00
0.00
0.00
5.00
0.00
0
634.00
0.00
0.00
0.00
10.00
0.88
4,135
634.40
0.04
0.04
0.00
15.00
1.80
51,944
638.04
1.97
1.97
0.00
20.00
0.79
44,495
637.56
1.46
1.46
0.00
25.00
0.00
31,813
636.67
1.07
1.07
0.00
30.00
0.00
19,695
635.75
0.29
0.29
0.00
35.00
0.00
16,720
635.50
0.12
0.12
0.00
40.00
0.00
14,716
635.34
0.11
0.11
0.00
45.00
0.00
12,826
635.18
0.10
0.10
0.00
50.00
0.00
11,047
635.02
0.10
0.10
0.00
55.00
0.00
9,425
634.88
0.08
0.08
0.00
60.00
0.00
8,029
634.76
0.07
0.07
0.00
65.00
0.00
6,832
634.65
0.06
0.06
0.00
70.00
0.00
5,808
634.55
0.05
0.05
0.00
75.00
0.00
4,933
634.47
0.04
0.04
0.00
80.00
0.00
4,186
634.40
0.04
0.04
0.00
85.00
0.00
3,550
634.34
0.03
0.03
0.00
90.00
0.00
3,009
634.29
0.03
0.03
0.00
95.00
0.00
2,549
634.25
0.02
0.02
0.00
100.00
0.00
2,159
634.21
0.02
0.02
0.00
105.00
0.00
1,827
634.18
0.02
0.02
0.00
110.00
0.00
1,546
634.15
0.01
0.01
0.00
115.00
0.00
1,308
634.13
0.01
0.01
0.00
120.00
0.00
1,107
634.11
0.01
0.01
0.00
125.00
0.00
936
634.09
0.01
0.01
0.00
130.00
0.00
791
634.08
0.01
0.01
0.00
135.00
0.00
669
634.07
0.01
0.01
0.00
140.00
0.00
566
634.06
0.01
0.01
0.00
145.00
0.00
478
634.05
0.00
0.00
0.00
150.00
0.00
404
634.04
0.00
0.00
0.00
155.00
0.00
342
634.03
0.00
0.00
0.00
160.00
0.00
289
634.03
0.00
0.00
0.00
165.00
0.00
244
634.02
0.00
0.00
0.00
170.00
0.00
206
634.02
0.00
0.00
0.00
175.00
0.00
174
634.02
0.00
0.00
0.00
180.00
0.00
147
634.01
0.00
0.00
0.00
185.00
0.00
125
634.01
0.00
0.00
0.00
190.00
0.00
105
634.01
0.00
0.00
0.00
195.00
0.00
89
634.01
0.00
0.00
0.00
200.00
0.00
75
634.01
0.00
0.00
0.00

2020.17-BM P2
Type // 24-hr 50-yr Concord Rainfall=6.80"
Prepared by {enter your company name here} Page 37
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 8/4/2022
Stage -Discharge for Pond 3P: (BMP2)
Elevation Discharge Primary Secondary
(feet)
(cfs)
(cfs)
(cfs)
634.00
0.00
0.00
0.00
634.10
0.01
0.01
0.00
634.20
0.02
0.02
0.00
634.30
0.03
0.03
0.00
634.40
0.04
0.04
0.00
634.50
0.05
0.05
0.00
634.60
0.06
0.06
0.00
634.70
0.07
0.07
0.00
634.80
0.08
0.08
0.00
634.90
0.09
0.09
0.00
635.00
0.10
0.10
0.00
635.10
0.10
0.10
0.00
635.20
0.10
0.10
0.00
635.30
0.11
0.11
0.00
635.40
0.11
0.11
0.00
635.50
0.11
0.11
0.00
635.60
0.15
0.15
0.00
635.70
0.23
0.23
0.00
635.80
0.36
0.36
0.00
635.90
0.49
0.49
0.00
636.00
0.61
0.61
0.00
636.10
0.70
0.70
0.00
636.20
0.78
0.78
0.00
636.30
0.85
0.85
0.00
636.40
0.91
0.91
0.00
636.50
0.97
0.97
0.00
636.60
1.03
1.03
0.00
636.70
1.08
1.08
0.00
636.80
1.13
1.13
0.00
636.90
1.18
1.18
0.00
637.00
1.23
1.23
0.00
637.10
1.27
1.27
0.00
637.20
1.32
1.32
0.00
637.30
1.36
1.36
0.00
637.40
1.40
1.40
0.00
637.50
1.44
1.44
0.00
637.60
1.48
1.48
0.00
637.70
1.52
1.52
0.00
637.80
1.56
1.56
0.00
637.90
1.59
1.59
0.00
638.00
1.63
1.63
0.00
638.10
2.70
2.70
0.00
638.20
4.62
4.62
0.00
638.30
7.10
7.10
0.00
638.40
10.04
10.04
0.00
638.50
13.36
13.36
0.00
638.60
17.03
17.03
0.00
638.70
21.01
21.01
0.00
638.80
23.53
23.53
0.00
638.90
23.69
23.69
0.00
639.00
23.84
23.84
0.00
639.10
24.84
23.99
0.85
Elevation Discharge Primary Secondary
(feet)
(cfs)
(cfs)
(cfs)
639.20
26.54
24.14
2.40
639.30
28.71
24.29
4.42
639.40
31.27
24.44
6.83
639.50
34.13
24.59
9.55
639.60
37.28
24.73
12.55
639.70
40.52
24.88
15.64
639.80
43.92
25.03
18.89
639.90
47.67
25.17
22.50
640.00
51.61
25.31
26.30

2020.17-BM P2
Type // 24-hr 50-yr Concord Rainfall=6.80"
Prepared by {enter your company name here} Page 38
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 8/4/2022
Stage -Area -Storage for Pond 3P: (BMP2)
Elevation
Surface
Storage
(feet)
(sq-ft)
(cubic -feet)
634.00
10,132
0
634.10
10,264
1,020
634.20
10,396
2,053
634.30
10,527
3,099
634.40
10,659
4,158
634.50
10,791
5,231
634.60
10,923
6,316
634.70
11,054
7,415
634.80
11,186
8,527
634.90
11,318
9,652
635.00
11,450
10,791
635.10
11,581
11,942
635.20
11,713
13,107
635.30
11,845
14,285
635.40
11,976
15,476
635.50
12,108
16,680
635.60
12,240
17,898
635.70
12,372
19,128
635.80
12,503
20,372
635.90
12,635
21,629
636.00
12,767
22,899
636.10
12,910
24,183
636.20
13,053
25,481
636.30
13,196
26,793
636.40
13,339
28,120
636.50
13,482
29,461
636.60
13,625
30,817
636.70
13,768
32,186
636.80
13,911
33,570
636.90
14,054
34,968
637.00
14,197
36,381
637.10
14,340
37,808
637.20
14,483
39,249
637.30
14,626
40,704
637.40
14,769
42,174
637.50
14,912
43,658
637.60
15,055
45,157
637.70
15,198
46,669
637.80
15,341
48,196
637.90
15,484
49,737
638.00
15,627
51,293
638.10
15,781
52,863
638.20
15,936
54,449
638.30
16,090
56,051
638.40
16,244
57,667
638.50
16,399
59,299
638.60
16,553
60,947
638.70
16,707
62,610
638.80
16,861
64,288
638.90
17,016
65,982
639.00
17,170
67,692
639.10
17,324
69,416
Elevation
Surface
Storage
(feet)
(sq-ft)
(cubic -feet)
639.20
17,479
71,156
639.30
17,633
72,912
639.40
17,787
74,683
639.50
17,942
76,469
639.60
18,096
78,271
639.70
18,250
80,089
639.80
18,404
81,921
639.90
18,559
83,769
640.00
18,713
85,633

SAND FILTER-3
- ------------
... ..
. -
. . . _ . . .
am 4)4.po Can
... .................

Mt. Pleasant, NC
Sand Filter Calculation
1. Calculate Runoff Coeff, (Rv)
Drainage area to filter, Ad =
Impervious area to filter forebay=
Impervious percentage =
Rv = 0.05 + 0.9(la) _
2. Calculate req'd water quality volume (WQV)
Brighton Park
3
8.87 ac
4.05 ac.
45.63%
0.46066442
Storage:
Cum
Elev.
Area
Vol.
Vol
628
9379
0
0
630
11768
21147
21147
632
14381
26149
47296
634
17222
31603
78899
Calculate Depth for WQ Volume:
628
0
629.40
14833
630
21147
Elevation of WQ Volume = 629.40
3. Convert Water Quality Volume, WQv to inches of runoff.
WQv = 1.0(Rv) = 0.46 inches
4. Site Hydrologic Input Parameters:
WQV = (Rv/1 x Ad/1 x 43560 sf/1 ac x Rd/1 x ft/12 in)
WQV = 14833 cf (used to size Af)
WQV= 0.3405 ac-ft.
Cn Pre = 66.0
Cn Post = 76.0 to pond

Table 4.8.3 Results of Hvdrolooic Calculations from HvdroCad
Condition
Q 1- ear
Q 10- r.
Q 25- r
Q 50 yr
Runoff
Pre Dev.
4.12
18.73
25.90
32.62
Post. Dev.
15.55
42.97
55.04
65.94
Routed
0.40
1.92
9.29
25.29
Peak Stage
629.84
632.04
632.38
632.8
Disch. Time
1115 hours
1
1
11.2' Freeboard
Required
5. First 1/2 inch 0.37 ac-ft 16099.05 cf
Detain 18 hrs 18985 cf Provided
36 hrs 12851 cf
Release Peak-36 hrs 17682 cf Provided
6. Channel Protection Volume: CPv to be held for 24 hours + 12 hours = 36 hours
S = 1000/Cn-10 where Cn = 76.0
S = 3.16 inches
Compute total runoff for the 1-year, 24-hour storm event. Total rainfall depth is
Qd = (P-0.2S)^2/(P+0.8S) 2.9 1-year storm
Qd= 0.95 inches
Watershed Runoff = (Qd)(DA)(1 ft/12") = 0.70 ac-ft. = 0.701 per Hydro -CAD
From HydroCad- Max Release Rate = 0.40 cfs
From HydroCad: Maximum Stage: 629.84
Storage: 19117 cf
Drawdown Time: 115 hours
7. Sedimentation Basin Surface Area
Min As = 0.20 x WQV = As = 2967 sf
8. Sand Filter Bed Surface Area (Af)
1359 sf
Af = (WQV x df)/(k x t x (ha + df) ha = average head
df = 1.5 (depth of filter media)
hmax = 1.40
OK
Calculate Ha = hmax/2 = 0.70 ft
Where df = depth of filter bed (25), k = permeability of sand (3.5), ha = avg depth, t=51 hrs=2.125 days
Af = 1359 sf 198.40 cf/hr = 0.05511 cfs
hmax = 1.402801248 14833 cf/(As + Af)
Choose As + Af = 4325 sf
Per plan, As = 5490
Af = 3890
Total 9380 OK

9. Sand Filter Drawdown Calculation
Coeff. Of Permeability of filter media = 3.5ft/day = 0.146 ft/hr
Volume of water drained in one hour = 0.146 ft/hr x Af s.f. = 198.396 cf/hour
Drawdown Time = WQV/Drawdown Rate = 74.76 hrs 3.115091 days
Underdrain Calculations:
78 I.f of underdrain shown; provide 6" perforated pvc pipe with 3/8" perforations spaces 3" o.c. - 4 longitudinal rows
spaced 90 degrees apart.
110 I.f. of pipe
110 I.f. x 4 rows/ft x 4 holes/ft =
50% of perforations =
Capacity of one hole =
1760 holes
880 holes
0.0083 cfs based upon CA(2gh)^0.5
Total Capacity = 7.304 cfs which is 132.5 times the capacity of the sand filter.
Total Capacityof 6" PVC @ 0.50% is 0.40 cfs (0.20 cfs assuming 50% clogged) from Mannings and BMP Manual.
10. Antiflotation Calculation
10 Height of Riser, ft.
6 Area of Riser, s.f.
60 Volume of Riser, c.f.
3744 Weight of Water @ 62.4 pcf
4118.4 Weight of water with safety factor of 1.1
82.6 Buoyant Wt. of Concrete = (145-62.4) pcf
1.85 Volume of Concrete Req'd in c.y.
49.86 Volume of Concrete Req'd in c.f.
60 Volume of Concrete in Structure (cf)
-10.14 Volume of Concrete Required (cf)
0.5 ft thick
3.2 Length/Width
(If negative, additional concrete weight not required)

Brighton Park
Mt. Pleasant, NC
1. Develop Stage -Discharge Data for Sand Filter Media.
From 4.8.18 of the BMP Standards Manual:
Q = Af(k)(h+df)/(df)
Latham -Walters Engineering, Inc.
16507-A Northcross Drive
Huntersville, NC 28078
where Af = surface area of filter bed = sf
df = filter bed depth, ft. = ft.
k = coefficient of permeability of filter media (ft/day) = ft/day
h = average height of water above filter bed (ft) 12, etc.
h
Q
cf/day
Q
cfs
1
7926.782
0.092
2
11097.49
0.128
3
14268.21
0.165
4
17438.92
0.202
5
20609.63
0.239
6
23780.35
0.275
7
26951.06
0.312
8
30121.77
0.349
9
33292.48
0.385
10
36463.2
0.422

is
(Predeveloped)
2S v A P
(Post Developed)
Subcat Reach on Link
(BMP3)

2020.17-BM P3
Prepared by {enter your company name here} Page 2
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Area Listing (all nodes)
Area (acres) CN Description (subcats)
4.340 60 Woods, Fair, HSG B (1S)
2.540 69 Pasture/grassland/range, Fair, HSG B (1S)
0.900 73 Woods, Fair, HSG C (1 S)
7.240 75 RM-2 (B) (2S)
1.090 79 Pasture/grassland/range, Fair, HSG C (1S)
1.630 83 RM-2 (C) (2S)
iiMEI]

2020.17-BMP3 Type 11 24-hr 1-yr Concord Rainfall=2.90"
Prepared by {enter your company name here} Page 3
HvdroCAD® 8.00 s/n 004317 © 2006 HvdroCAD Software Solutions LLC 6/5/2022
Time span=0.00-200.00 hrs, dt=0.01 hrs, 20001 points
Runoff by SCS TR-20 method, UH=SCS
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment 1S: (Predeveloped) Runoff Area=8.870 ac Runoff Depth=0.50"
Flow Length=568' Tc=17.1 min CN=66 Runoff=4.12 cfs 0.368 of
Subcatchment 2S: (Post Developed) Runoff Area=8.870 ac Runoff Depth=0.95"
Tc=5.0 min CN=76 Runoff=15.55 cfs 0.701 of
Pond 3P: (BMP3) Peak Elev=629.84' Storage=19,241 cf Inflow=15.55 cfs 0.701 of
Primary=0.40 cfs 0.700 of Secondary=0.00 cfs 0.000 of Outflow=0.40 cfs 0.700 of
Total Runoff Area = 17.740 ac Runoff Volume = 1.069 of Average Runoff Depth = 0.72"
100.00% Pervious Area = 17.740 ac 0.00% Impervious Area = 0.000 ac

2020.17-BM P3
Type 11 24-hr 1-yr Concord Rainfall=2.90"
Prepared by {enter your company name here} Page 4
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Subcatchment 1S: (Predeveloped)
BASED ON EXISTING CONDITIONS
Runoff = 4.12 cfs @ 12.13 hrs, Volume= 0.368 af, Depth= 0.50"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Type II 24-hr 1-yr Concord Rainfall=2.90"
Area (ac)
CN
Description
4.340
60
Woods, Fair, HSG B
0.900
73
Woods, Fair, HSG C
1.090
79
Pasture/grassland/range, Fair, HSG C
2.540
69
Pasture/grassland/range, Fair, HSG B
8.870
66
Weighted Average
8.870
Pervious Area
Tc
Length
Slope
Velocity
Capacity Description
(min)
(feet)
(ft/ft)
(ft/sec)
(cfs)
11.8
100
0.0288
0.14
Sheet Flow,
Grass: Dense n= 0.240 P2= 3.50"
5.3
468
0.0880
1.48
Shallow Concentrated Flow,
Woodland Kv= 5.0 fps
17.1 568 Total

2020.17-BM P3
Type // 24-hr 1-yr Concord Rainfall=2.90"
Prepared by {enter your company name here} Page 5
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Hydrograph for Subcatchment 1S: (Predeveloped)
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
0.00
0.00
0.00
0.00
2.00
0.06
0.00
0.00
4.00
0.14
0.00
0.00
6.00
0.23
0.00
0.00
8.00
0.35
0.00
0.00
10.00
0.52
0.00
0.00
12.00
1.92
0.13
2.00
14.00
2.38
0.28
0.40
16.00
2.55
0.35
0.26
18.00
2.67
0.40
0.20
20.00
2.76
0.44
0.16
22.00
2.83
0.47
0.14
24.00
2.90
0.50
0.13
26.00
2.90
0.50
0.00
28.00
2.90
0.50
0.00
30.00
2.90
0.50
0.00
32.00
2.90
0.50
0.00
34.00
2.90
0.50
0.00
36.00
2.90
0.50
0.00
38.00
2.90
0.50
0.00
40.00
2.90
0.50
0.00
42.00
2.90
0.50
0.00
44.00
2.90
0.50
0.00
46.00
2.90
0.50
0.00
48.00
2.90
0.50
0.00
50.00
2.90
0.50
0.00
52.00
2.90
0.50
0.00
54.00
2.90
0.50
0.00
56.00
2.90
0.50
0.00
58.00
2.90
0.50
0.00
60.00
2.90
0.50
0.00
62.00
2.90
0.50
0.00
64.00
2.90
0.50
0.00
66.00
2.90
0.50
0.00
68.00
2.90
0.50
0.00
70.00
2.90
0.50
0.00
72.00
2.90
0.50
0.00
74.00
2.90
0.50
0.00
76.00
2.90
0.50
0.00
78.00
2.90
0.50
0.00
80.00
2.90
0.50
0.00
82.00
2.90
0.50
0.00
84.00
2.90
0.50
0.00
86.00
2.90
0.50
0.00
88.00
2.90
0.50
0.00
90.00
2.90
0.50
0.00
92.00
2.90
0.50
0.00
94.00
2.90
0.50
0.00
96.00
2.90
0.50
0.00
98.00
2.90
0.50
0.00
100.00
2.90
0.50
0.00
102.00
2.90
0.50
0.00
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
104.00
2.90
0.50
0.00
106.00
2.90
0.50
0.00
108.00
2.90
0.50
0.00
110.00
2.90
0.50
0.00
112.00
2.90
0.50
0.00
114.00
2.90
0.50
0.00
116.00
2.90
0.50
0.00
118.00
2.90
0.50
0.00
120.00
2.90
0.50
0.00
122.00
2.90
0.50
0.00
124.00
2.90
0.50
0.00
126.00
2.90
0.50
0.00
128.00
2.90
0.50
0.00
130.00
2.90
0.50
0.00
132.00
2.90
0.50
0.00
134.00
2.90
0.50
0.00
136.00
2.90
0.50
0.00
138.00
2.90
0.50
0.00
140.00
2.90
0.50
0.00
142.00
2.90
0.50
0.00
144.00
2.90
0.50
0.00
146.00
2.90
0.50
0.00
148.00
2.90
0.50
0.00
150.00
2.90
0.50
0.00
152.00
2.90
0.50
0.00
154.00
2.90
0.50
0.00
156.00
2.90
0.50
0.00
158.00
2.90
0.50
0.00
160.00
2.90
0.50
0.00
162.00
2.90
0.50
0.00
164.00
2.90
0.50
0.00
166.00
2.90
0.50
0.00
168.00
2.90
0.50
0.00
170.00
2.90
0.50
0.00
172.00
2.90
0.50
0.00
174.00
2.90
0.50
0.00
176.00
2.90
0.50
0.00
178.00
2.90
0.50
0.00
180.00
2.90
0.50
0.00
182.00
2.90
0.50
0.00
184.00
2.90
0.50
0.00
186.00
2.90
0.50
0.00
188.00
2.90
0.50
0.00
190.00
2.90
0.50
0.00
192.00
2.90
0.50
0.00
194.00
2.90
0.50
0.00
196.00
2.90
0.50
0.00
198.00
2.90
0.50
0.00
200.00
2.90
0.50
0.00

2020.17-BM P3 Type 11 24-hr 1-yr Concord Rainfall=2.90"
Prepared by {enter your company name here} Page 6
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Subcatchment 2S: (Post Developed)
Runoff = 15.55 cfs @ 11.97 hrs, Volume= 0.701 af, Depth= 0.95"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Type II 24-hr 1-yr Concord Rainfall=2.90"
Area (ac) CN
Description
1.630 83
RM-2 (C)
7.240 75
RM-2 (B)
8.870 76
Weighted Average
8.870
Pervious Area
Tc Length
Slope Velocity Capacity Description
(min) (feet)
(ft/ft) (ft/sec) (cfs)
5.0
Direct Entry,

2020.17-BM P3
Type // 24-hr 1-yr Concord Rainfall=2.90"
Prepared by {enter your company name here} Page 7
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Hydrograph for Subcatchment 2S: (Post Developed)
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
0.00
0.00
0.00
0.00
2.00
0.06
0.00
0.00
4.00
0.14
0.00
0.00
6.00
0.23
0.00
0.00
8.00
0.35
0.00
0.00
10.00
0.52
0.00
0.00
12.00
1.92
0.37
13.85
14.00
2.38
0.62
0.58
16.00
2.55
0.73
0.37
18.00
2.67
0.80
0.30
20.00
2.76
0.86
0.22
22.00
2.83
0.90
0.20
24.00
2.90
0.95
0.19
26.00
2.90
0.95
0.00
28.00
2.90
0.95
0.00
30.00
2.90
0.95
0.00
32.00
2.90
0.95
0.00
34.00
2.90
0.95
0.00
36.00
2.90
0.95
0.00
38.00
2.90
0.95
0.00
40.00
2.90
0.95
0.00
42.00
2.90
0.95
0.00
44.00
2.90
0.95
0.00
46.00
2.90
0.95
0.00
48.00
2.90
0.95
0.00
50.00
2.90
0.95
0.00
52.00
2.90
0.95
0.00
54.00
2.90
0.95
0.00
56.00
2.90
0.95
0.00
58.00
2.90
0.95
0.00
60.00
2.90
0.95
0.00
62.00
2.90
0.95
0.00
64.00
2.90
0.95
0.00
66.00
2.90
0.95
0.00
68.00
2.90
0.95
0.00
70.00
2.90
0.95
0.00
72.00
2.90
0.95
0.00
74.00
2.90
0.95
0.00
76.00
2.90
0.95
0.00
78.00
2.90
0.95
0.00
80.00
2.90
0.95
0.00
82.00
2.90
0.95
0.00
84.00
2.90
0.95
0.00
86.00
2.90
0.95
0.00
88.00
2.90
0.95
0.00
90.00
2.90
0.95
0.00
92.00
2.90
0.95
0.00
94.00
2.90
0.95
0.00
96.00
2.90
0.95
0.00
98.00
2.90
0.95
0.00
100.00
2.90
0.95
0.00
102.00
2.90
0.95
0.00
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
104.00
2.90
0.95
0.00
106.00
2.90
0.95
0.00
108.00
2.90
0.95
0.00
110.00
2.90
0.95
0.00
112.00
2.90
0.95
0.00
114.00
2.90
0.95
0.00
116.00
2.90
0.95
0.00
118.00
2.90
0.95
0.00
120.00
2.90
0.95
0.00
122.00
2.90
0.95
0.00
124.00
2.90
0.95
0.00
126.00
2.90
0.95
0.00
128.00
2.90
0.95
0.00
130.00
2.90
0.95
0.00
132.00
2.90
0.95
0.00
134.00
2.90
0.95
0.00
136.00
2.90
0.95
0.00
138.00
2.90
0.95
0.00
140.00
2.90
0.95
0.00
142.00
2.90
0.95
0.00
144.00
2.90
0.95
0.00
146.00
2.90
0.95
0.00
148.00
2.90
0.95
0.00
150.00
2.90
0.95
0.00
152.00
2.90
0.95
0.00
154.00
2.90
0.95
0.00
156.00
2.90
0.95
0.00
158.00
2.90
0.95
0.00
160.00
2.90
0.95
0.00
162.00
2.90
0.95
0.00
164.00
2.90
0.95
0.00
166.00
2.90
0.95
0.00
168.00
2.90
0.95
0.00
170.00
2.90
0.95
0.00
172.00
2.90
0.95
0.00
174.00
2.90
0.95
0.00
176.00
2.90
0.95
0.00
178.00
2.90
0.95
0.00
180.00
2.90
0.95
0.00
182.00
2.90
0.95
0.00
184.00
2.90
0.95
0.00
186.00
2.90
0.95
0.00
188.00
2.90
0.95
0.00
190.00
2.90
0.95
0.00
192.00
2.90
0.95
0.00
194.00
2.90
0.95
0.00
196.00
2.90
0.95
0.00
198.00
2.90
0.95
0.00
200.00
2.90
0.95
0.00

2020.17-BMP3 Type 11 24-hr 1-yr Concord Rainfall=2.90"
Prepared by {enter your company name here} Page 8
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Pond 3P: (BMP3)
Inflow Area = 8.870 ac, Inflow Depth = 0.95" for 1-yr Concord event
Inflow =
15.55 cfs @
11.97 hrs,
Volume=
0.701 of
Outflow =
0.40 cfs @
15.75 hrs,
Volume=
0.700 af, Atten= 97%, Lag= 226.8 min
Primary =
0.40 cfs @
15.75 hrs,
Volume=
0.700 of
Secondary =
0.00 cfs @
0.00 hrs,
Volume=
0.000 of
Routing by Stor-Ind method, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Peak Elev= 629.84' @ 15.75 hrs Surf.Area= 11,573 sf Storage= 19,241 cf
Plug -Flow detention time= 1,497.0 min calculated for 0.700 of (100% of inflow)
Center -of -Mass det. time= 1,496.6 min ( 2,353.9 - 857.3 )
Volume Invert Avail.Storage Storage Description
#1 628.00' 78,899 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic -feet) (cubic -feet)
628.00 9,379 0 0
630.00 11,768 21,147 21,147
632.00 14,381 26,149 47,296
634.00 17,222 31,603 78,899
Device Routing Invert Outlet Devices
#1 Primary 614.18' 18.0" x 30.0' long Culvert RCP, square edge headwall, Ke= 0.500
Outlet Invert= 614.00' S= 0.0060 7' Cc= 0.900 n= 0.013
#2 Device 1 628.00' Exfiltration
Head (feet) 0.00 1.00 2.00 3.00 4.00 5.00 6.00
Disch. (cfs) 0.000 0.092 0.128 0.165 0.202 0.239 0.275
#3 Device 1 629.50' 6.0" Vert. Orifice/Grate C= 0.600
#4 Device 1 632.00' 2.00' x 3.00' Horiz. Top of Riser Limited to weir flow C= 0.600
#5 Secondary 633.00' 10.0' long x 16.0' breadth Spillway
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Coef. (English) 2.68 2.70 2.70 2.64 2.63 2.64 2.64 2.63
Primary OutFlow Max=0.40 cfs @ 15.75 hrs HW=629.84' (Free Discharge)
L1=Culvert (Passes 0.40 cfs of 32.85 cfs potential flow)
2=Exfltration (Custom Controls 0.12 cfs)
3=Orifice/Grate (Orifice Controls 0.28 cfs @ 1.98 fps)
=Top of Riser ( Controls 0.00 cfs)
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=628.00' (Free Discharge)
5=Spillway ( Controls 0.00 cfs)

2020.17-BM P3
Type // 24-hr 1-yr Concord Rainfall=2.90"
Prepared by {enter your company name here} Page 9
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Hydrograph for Pond 3P: (BMP3)
Time
Inflow
Storage
Elevation
Outflow
Primary
Secondary
(hours)
(cfs)
(cubic -feet)
(feet)
(cfs)
(cfs)
(cfs)
0.00
0.00
0
628.00
0.00
0.00
0.00
5.00
0.00
0
628.00
0.00
0.00
0.00
10.00
0.00
0
628.00
0.00
0.00
0.00
15.00
0.48
19,128
629.83
0.39
0.39
0.00
20.00
0.22
18,372
629.76
0.30
0.30
0.00
25.00
0.00
16,954
629.64
0.17
0.17
0.00
30.00
0.00
14,737
629.44
0.11
0.11
0.00
35.00
0.00
12,852
629.27
0.10
0.10
0.00
40.00
0.00
11,076
629.10
0.10
0.10
0.00
45.00
0.00
9,414
628.95
0.09
0.09
0.00
50.00
0.00
7,964
628.81
0.07
0.07
0.00
55.00
0.00
6,729
628.69
0.06
0.06
0.00
60.00
0.00
5,679
628.58
0.05
0.05
0.00
65.00
0.00
4,787
628.49
0.05
0.05
0.00
70.00
0.00
4,033
628.42
0.04
0.04
0.00
75.00
0.00
3,394
628.35
0.03
0.03
0.00
80.00
0.00
2,855
628.30
0.03
0.03
0.00
85.00
0.00
2,400
628.25
0.02
0.02
0.00
90.00
0.00
2,017
628.21
0.02
0.02
0.00
95.00
0.00
1,694
628.18
0.02
0.02
0.00
100.00
0.00
1,423
628.15
0.01
0.01
0.00
105.00
0.00
1,194
628.13
0.01
0.01
0.00
110.00
0.00
1,002
628.11
0.01
0.01
0.00
115.00
0.00
841
628.09
0.01
0.01
0.00
120.00
0.00
706
628.07
0.01
0.01
0.00
125.00
0.00
592
628.06
0.01
0.01
0.00
130.00
0.00
497
628.05
0.00
0.00
0.00
135.00
0.00
416
628.04
0.00
0.00
0.00
140.00
0.00
349
628.04
0.00
0.00
0.00
145.00
0.00
293
628.03
0.00
0.00
0.00
150.00
0.00
246
628.03
0.00
0.00
0.00
155.00
0.00
206
628.02
0.00
0.00
0.00
160.00
0.00
173
628.02
0.00
0.00
0.00
165.00
0.00
145
628.02
0.00
0.00
0.00
170.00
0.00
122
628.01
0.00
0.00
0.00
175.00
0.00
102
628.01
0.00
0.00
0.00
180.00
0.00
86
628.01
0.00
0.00
0.00
185.00
0.00
72
628.01
0.00
0.00
0.00
190.00
0.00
60
628.01
0.00
0.00
0.00
195.00
0.00
50
628.01
0.00
0.00
0.00
200.00
0.00
42
628.00
0.00
0.00
0.00

2020.17-BM P3
Type 11 24-hr 1-yr Concord Rainfall=2.90"
Prepared by {enter your company name here} Page 10
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Stage -Discharge for Pond 3P: (BMP3)
Elevation Discharge Primary Secondary
(feet)
(cfs)
(cfs)
(cfs)
628.00
0.00
0.00
0.00
628.10
0.01
0.01
0.00
628.20
0.02
0.02
0.00
628.30
0.03
0.03
0.00
628.40
0.04
0.04
0.00
628.50
0.05
0.05
0.00
628.60
0.06
0.06
0.00
628.70
0.06
0.06
0.00
628.80
0.07
0.07
0.00
628.90
0.08
0.08
0.00
629.00
0.09
0.09
0.00
629.10
0.10
0.10
0.00
629.20
0.10
0.10
0.00
629.30
0.10
0.10
0.00
629.40
0.11
0.11
0.00
629.50
0.11
0.11
0.00
629.60
0.14
0.14
0.00
629.70
0.23
0.23
0.00
629.80
0.35
0.35
0.00
629.90
0.49
0.49
0.00
630.00
0.60
0.60
0.00
630.10
0.69
0.69
0.00
630.20
0.77
0.77
0.00
630.30
0.84
0.84
0.00
630.40
0.91
0.91
0.00
630.50
0.97
0.97
0.00
630.60
1.02
1.02
0.00
630.70
1.08
1.08
0.00
630.80
1.13
1.13
0.00
630.90
1.18
1.18
0.00
631.00
1.22
1.22
0.00
631.10
1.27
1.27
0.00
631.20
1.31
1.31
0.00
631.30
1.35
1.35
0.00
631.40
1.39
1.39
0.00
631.50
1.43
1.43
0.00
631.60
1.47
1.47
0.00
631.70
1.51
1.51
0.00
631.80
1.55
1.55
0.00
631.90
1.58
1.58
0.00
632.00
1.62
1.62
0.00
632.10
2.69
2.69
0.00
632.20
4.61
4.61
0.00
632.30
7.10
7.10
0.00
632.40
10.03
10.03
0.00
632.50
13.35
13.35
0.00
632.60
17.02
17.02
0.00
632.70
21.00
21.00
0.00
632.80
25.28
25.28
0.00
632.90
29.32
29.32
0.00
633.00
30.83
30.83
0.00
633.10
33.12
32.27
0.85
Elevation Discharge Primary Secondary
(feet)
(cfs)
(cfs)
(cfs)
633.20
36.05
33.65
2.40
633.30
39.39
34.97
4.42
633.40
43.07
36.24
6.83
633.50
46.21
36.67
9.55
633.60
49.31
36.77
12.55
633.70
52.50
36.86
15.64
633.80
55.85
36.96
18.89
633.90
59.56
37.06
22.50
634.00
63.46
37.16
26.30

2020.17-BM P3
Type 11 24-hr 1-yr Concord Rainfall=2.90"
Prepared by {enter your company name here} Page 11
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Stage -Area -Storage for Pond 3P: (BMP3)
Elevation
Surface
Storage
(feet)
(sq-ft)
(cubic -feet)
628.00
9,379
0
628.10
9,498
944
628.20
9,618
1,900
628.30
9,737
2,867
628.40
9,857
3,847
628.50
9,976
4,839
628.60
10,096
5,842
628.70
10,215
6,858
628.80
10,335
7,885
628.90
10,454
8,925
629.00
10,574
9,976
629.10
10,693
11,040
629.20
10,812
12,115
629.30
10,932
13,202
629.40
11,051
14,301
629.50
11,171
15,412
629.60
11,290
16,535
629.70
11,410
17,670
629.80
11,529
18,817
629.90
11,649
19,976
630.00
11,768
21,147
630.10
11,899
22,330
630.20
12,029
23,527
630.30
12,160
24,736
630.40
12,291
25,959
630.50
12,421
27,194
630.60
12,552
28,443
630.70
12,683
29,705
630.80
12,813
30,979
630.90
12,944
32,267
631.00
13,075
33,568
631.10
13,205
34,882
631.20
13,336
36,209
631.30
13,466
37,549
631.40
13,597
38,903
631.50
13,728
40,269
631.60
13,858
41,648
631.70
13,989
43,040
631.80
14,120
44,446
631.90
14,250
45,864
632.00
14,381
47,296
632.10
14,523
48,741
632.20
14,665
50,201
632.30
14,807
51,674
632.40
14,949
53,162
632.50
15,091
54,664
632.60
15,233
56,180
632.70
15,375
57,711
632.80
15,517
59,255
632.90
15,659
60,814
633.00
15,802
62,387
633.10
15,944
63,975
Elevation
Surface
Storage
(feet)
(sq-ft)
(cubic -feet)
633.20
16,086
65,576
633.30
16,228
67,192
633.40
16,370
68,821
633.50
16,512
70,466
633.60
16,654
72,124
633.70
16,796
73,796
633.80
16,938
75,483
633.90
17,080
77,184
634.00
17,222
78,899

2020.17-BM P3 Type 11 24-hr 10-yr Concord Rainfall=5.10"
Prepared by {enter your company name here} Page 12
HvdroCAD® 8.00 s/n 004317 © 2006 HvdroCAD Software Solutions LLC 6/5/2022
Time span=0.00-200.00 hrs, dt=0.01 hrs, 20001 points
Runoff by SCS TR-20 method, UH=SCS
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment 1S: (Predeveloped) Runoff Area=8.870 ac Runoff Depth=1.80"
Flow Length=568' Tc=17.1 min CN=66 Runoff=18.73 cfs 1.328 of
Subcatchment 2S: (Post Developed) Runoff Area=8.870 ac Runoff Depth=2.62"
Tc=5.0 min CN=76 Runoff=42.97 cfs 1.935 of
Pond 3P: (BMP3) Peak Elev=632.04' Storage=47,847 cf Inflow=42.97 cfs 1.935 of
Primary=1.92 cfs 1.934 of Secondary=0.00 cfs 0.000 of Outflow=1.92 cfs 1.934 of
Total Runoff Area = 17.740 ac Runoff Volume = 3.263 of Average Runoff Depth = 2.21"
100.00% Pervious Area = 17.740 ac 0.00% Impervious Area = 0.000 ac

2020.17-BM P3
Type 11 24-hr 10-yr Concord Rainfall=5.10"
Prepared by {enter your company name here} Page 13
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Subcatchment 1S: (Predeveloped)
BASED ON EXISTING CONDITIONS
Runoff = 18.73 cfs @ 12.10 hrs, Volume= 1.328 af, Depth= 1.80"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Type II 24-hr 10-yr Concord Rainfall=5.10"
Area (ac)
CN
Description
4.340
60
Woods, Fair, HSG B
0.900
73
Woods, Fair, HSG C
1.090
79
Pasture/grassland/range, Fair, HSG C
2.540
69
Pasture/grassland/range, Fair, HSG B
8.870
66
Weighted Average
8.870
Pervious Area
Tc
Length
Slope
Velocity
Capacity Description
(min)
(feet)
(ft/ft)
(ft/sec)
(cfs)
11.8
100
0.0288
0.14
Sheet Flow,
Grass: Dense n= 0.240 P2= 3.50"
5.3
468
0.0880
1.48
Shallow Concentrated Flow,
Woodland Kv= 5.0 fps
17.1 568 Total

2020.17-BM P3
Type 11 24-hr 10-yr Concord Rainfall=5.10"
Prepared by {enter your company name here} Page 14
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Hydrograph for Subcatchment 1S: (Predeveloped)
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
0.00
0.00
0.00
0.00
2.00
0.11
0.00
0.00
4.00
0.24
0.00
0.00
6.00
0.41
0.00
0.00
8.00
0.61
0.00
0.00
10.00
0.92
0.00
0.00
12.00
3.38
0.74
12.99
14.00
4.18
1.20
1.18
16.00
4.49
1.39
0.72
18.00
4.70
1.52
0.56
20.00
4.86
1.63
0.42
22.00
4.98
1.72
0.38
24.00
5.10
1.80
0.35
26.00
5.10
1.80
0.00
28.00
5.10
1.80
0.00
30.00
5.10
1.80
0.00
32.00
5.10
1.80
0.00
34.00
5.10
1.80
0.00
36.00
5.10
1.80
0.00
38.00
5.10
1.80
0.00
40.00
5.10
1.80
0.00
42.00
5.10
1.80
0.00
44.00
5.10
1.80
0.00
46.00
5.10
1.80
0.00
48.00
5.10
1.80
0.00
50.00
5.10
1.80
0.00
52.00
5.10
1.80
0.00
54.00
5.10
1.80
0.00
56.00
5.10
1.80
0.00
58.00
5.10
1.80
0.00
60.00
5.10
1.80
0.00
62.00
5.10
1.80
0.00
64.00
5.10
1.80
0.00
66.00
5.10
1.80
0.00
68.00
5.10
1.80
0.00
70.00
5.10
1.80
0.00
72.00
5.10
1.80
0.00
74.00
5.10
1.80
0.00
76.00
5.10
1.80
0.00
78.00
5.10
1.80
0.00
80.00
5.10
1.80
0.00
82.00
5.10
1.80
0.00
84.00
5.10
1.80
0.00
86.00
5.10
1.80
0.00
88.00
5.10
1.80
0.00
90.00
5.10
1.80
0.00
92.00
5.10
1.80
0.00
94.00
5.10
1.80
0.00
96.00
5.10
1.80
0.00
98.00
5.10
1.80
0.00
100.00
5.10
1.80
0.00
102.00
5.10
1.80
0.00
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
104.00
5.10
1.80
0.00
106.00
5.10
1.80
0.00
108.00
5.10
1.80
0.00
110.00
5.10
1.80
0.00
112.00
5.10
1.80
0.00
114.00
5.10
1.80
0.00
116.00
5.10
1.80
0.00
118.00
5.10
1.80
0.00
120.00
5.10
1.80
0.00
122.00
5.10
1.80
0.00
124.00
5.10
1.80
0.00
126.00
5.10
1.80
0.00
128.00
5.10
1.80
0.00
130.00
5.10
1.80
0.00
132.00
5.10
1.80
0.00
134.00
5.10
1.80
0.00
136.00
5.10
1.80
0.00
138.00
5.10
1.80
0.00
140.00
5.10
1.80
0.00
142.00
5.10
1.80
0.00
144.00
5.10
1.80
0.00
146.00
5.10
1.80
0.00
148.00
5.10
1.80
0.00
150.00
5.10
1.80
0.00
152.00
5.10
1.80
0.00
154.00
5.10
1.80
0.00
156.00
5.10
1.80
0.00
158.00
5.10
1.80
0.00
160.00
5.10
1.80
0.00
162.00
5.10
1.80
0.00
164.00
5.10
1.80
0.00
166.00
5.10
1.80
0.00
168.00
5.10
1.80
0.00
170.00
5.10
1.80
0.00
172.00
5.10
1.80
0.00
174.00
5.10
1.80
0.00
176.00
5.10
1.80
0.00
178.00
5.10
1.80
0.00
180.00
5.10
1.80
0.00
182.00
5.10
1.80
0.00
184.00
5.10
1.80
0.00
186.00
5.10
1.80
0.00
188.00
5.10
1.80
0.00
190.00
5.10
1.80
0.00
192.00
5.10
1.80
0.00
194.00
5.10
1.80
0.00
196.00
5.10
1.80
0.00
198.00
5.10
1.80
0.00
200.00
5.10
1.80
0.00

2020.17-BM P3 Type 11 24-hr 10-yr Concord Rainfall=5.10"
Prepared by {enter your company name here} Page 15
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Subcatchment 2S: (Post Developed)
Runoff = 42.97 cfs @ 11.96 hrs, Volume= 1.935 af, Depth= 2.62"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Type II 24-hr 10-yr Concord Rainfall=5.10"
Area (ac) CN
Description
1.630 83
RM-2 (C)
7.240 75
RM-2 (B)
8.870 76
Weighted Average
8.870
Pervious Area
Tc Length
Slope Velocity Capacity Description
(min) (feet)
(ft/ft) (ft/sec) (cfs)
5.0
Direct Entry,

2020.17-BM P3
Type 11 24-hr 10-yr Concord Rainfall=5.10"
Prepared by {enter your company name here} Page 16
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Hydrograph for Subcatchment 2S: (Post Developed)
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
0.00
0.00
0.00
0.00
2.00
0.11
0.00
0.00
4.00
0.24
0.00
0.00
6.00
0.41
0.00
0.00
8.00
0.61
0.00
0.00
10.00
0.92
0.02
0.27
12.00
3.38
1.28
37.02
14.00
4.18
1.88
1.37
16.00
4.49
2.12
0.86
18.00
4.70
2.29
0.67
20.00
4.86
2.42
0.49
22.00
4.98
2.52
0.45
24.00
5.10
2.62
0.42
26.00
5.10
2.62
0.00
28.00
5.10
2.62
0.00
30.00
5.10
2.62
0.00
32.00
5.10
2.62
0.00
34.00
5.10
2.62
0.00
36.00
5.10
2.62
0.00
38.00
5.10
2.62
0.00
40.00
5.10
2.62
0.00
42.00
5.10
2.62
0.00
44.00
5.10
2.62
0.00
46.00
5.10
2.62
0.00
48.00
5.10
2.62
0.00
50.00
5.10
2.62
0.00
52.00
5.10
2.62
0.00
54.00
5.10
2.62
0.00
56.00
5.10
2.62
0.00
58.00
5.10
2.62
0.00
60.00
5.10
2.62
0.00
62.00
5.10
2.62
0.00
64.00
5.10
2.62
0.00
66.00
5.10
2.62
0.00
68.00
5.10
2.62
0.00
70.00
5.10
2.62
0.00
72.00
5.10
2.62
0.00
74.00
5.10
2.62
0.00
76.00
5.10
2.62
0.00
78.00
5.10
2.62
0.00
80.00
5.10
2.62
0.00
82.00
5.10
2.62
0.00
84.00
5.10
2.62
0.00
86.00
5.10
2.62
0.00
88.00
5.10
2.62
0.00
90.00
5.10
2.62
0.00
92.00
5.10
2.62
0.00
94.00
5.10
2.62
0.00
96.00
5.10
2.62
0.00
98.00
5.10
2.62
0.00
100.00
5.10
2.62
0.00
102.00
5.10
2.62
0.00
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
104.00
5.10
2.62
0.00
106.00
5.10
2.62
0.00
108.00
5.10
2.62
0.00
110.00
5.10
2.62
0.00
112.00
5.10
2.62
0.00
114.00
5.10
2.62
0.00
116.00
5.10
2.62
0.00
118.00
5.10
2.62
0.00
120.00
5.10
2.62
0.00
122.00
5.10
2.62
0.00
124.00
5.10
2.62
0.00
126.00
5.10
2.62
0.00
128.00
5.10
2.62
0.00
130.00
5.10
2.62
0.00
132.00
5.10
2.62
0.00
134.00
5.10
2.62
0.00
136.00
5.10
2.62
0.00
138.00
5.10
2.62
0.00
140.00
5.10
2.62
0.00
142.00
5.10
2.62
0.00
144.00
5.10
2.62
0.00
146.00
5.10
2.62
0.00
148.00
5.10
2.62
0.00
150.00
5.10
2.62
0.00
152.00
5.10
2.62
0.00
154.00
5.10
2.62
0.00
156.00
5.10
2.62
0.00
158.00
5.10
2.62
0.00
160.00
5.10
2.62
0.00
162.00
5.10
2.62
0.00
164.00
5.10
2.62
0.00
166.00
5.10
2.62
0.00
168.00
5.10
2.62
0.00
170.00
5.10
2.62
0.00
172.00
5.10
2.62
0.00
174.00
5.10
2.62
0.00
176.00
5.10
2.62
0.00
178.00
5.10
2.62
0.00
180.00
5.10
2.62
0.00
182.00
5.10
2.62
0.00
184.00
5.10
2.62
0.00
186.00
5.10
2.62
0.00
188.00
5.10
2.62
0.00
190.00
5.10
2.62
0.00
192.00
5.10
2.62
0.00
194.00
5.10
2.62
0.00
196.00
5.10
2.62
0.00
198.00
5.10
2.62
0.00
200.00
5.10
2.62
0.00

2020.17-BM P3 Type 11 24-hr 10-yr Concord Rainfall=5.10"
Prepared by {enter your company name here} Page 17
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Pond 3P: (BMP3)
Inflow Area = 8.870 ac, Inflow Depth = 2.62" for 10-yr Concord event
Inflow =
42.97 cfs @
11.96 hrs,
Volume=
1.935 of
Outflow =
1.92 cfs @
13.29 hrs,
Volume=
1.934 af, Atten= 96%, Lag= 79.7 min
Primary =
1.92 cfs @
13.29 hrs,
Volume=
1.934 of
Secondary =
0.00 cfs @
0.00 hrs,
Volume=
0.000 of
Routing by Stor-Ind method, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Peak Elev= 632.04' @ 13.29 hrs Surf.Area= 14,435 sf Storage= 47,847 cf
Plug -Flow detention time= 775.0 min calculated for 1.934 of (100% of inflow)
Center -of -Mass det. time= 775.1 min ( 1,602.4 - 827.3 )
Volume Invert Avail.Storage Storage Description
#1 628.00' 78,899 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic -feet) (cubic -feet)
628.00 9,379 0 0
630.00 11,768 21,147 21,147
632.00 14,381 26,149 47,296
634.00 17,222 31,603 78,899
Device Routing Invert Outlet Devices
#1 Primary 614.18' 18.0" x 30.0' long Culvert RCP, square edge headwall, Ke= 0.500
Outlet Invert= 614.00' S= 0.0060 7' Cc= 0.900 n= 0.013
#2 Device 1 628.00' Exfiltration
Head (feet) 0.00 1.00 2.00 3.00 4.00 5.00 6.00
Disch. (cfs) 0.000 0.092 0.128 0.165 0.202 0.239 0.275
#3 Device 1 629.50' 6.0" Vert. Orifice/Grate C= 0.600
#4 Device 1 632.00' 2.00' x 3.00' Horiz. Top of Riser Limited to weir flow C= 0.600
#5 Secondary 633.00' 10.0' long x 16.0' breadth Spillway
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Coef. (English) 2.68 2.70 2.70 2.64 2.63 2.64 2.64 2.63
Primary OutFlow Max=1.88 cfs @ 13.29 hrs HW=632.04' (Free Discharge)
L1=Culvert (Passes 1.88 cfs of 35.19 cfs potential flow)
2=Exfltration (Custom Controls 0.20 cfs)
3=Orifice/Grate (Orifice Controls 1.43 cfs @ 7.28 fps)
=Top of Riser (Weir Controls 0.24 cfs @ 0.64 fps)
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=628.00' (Free Discharge)
5=Spillway ( Controls 0.00 cfs)

2020.17-BM P3
Type 11 24-hr 10-yr Concord Rainfall=5.10"
Prepared by {enter your company name here} Page 18
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Hydrograph for Pond 3P: (BMP3)
Time
Inflow
Storage
Elevation
Outflow
Primary
Secondary
(hours)
(cfs)
(cubic -feet)
(feet)
(cfs)
(cfs)
(cfs)
0.00
0.00
0
628.00
0.00
0.00
0.00
5.00
0.00
0
628.00
0.00
0.00
0.00
10.00
0.27
702
628.07
0.01
0.01
0.00
15.00
1.10
45,991
631.91
1.59
1.59
0.00
20.00
0.49
33,564
631.00
1.22
1.22
0.00
25.00
0.00
22,412
630.11
0.70
0.70
0.00
30.00
0.00
16,423
629.59
0.14
0.14
0.00
35.00
0.00
14,366
629.41
0.11
0.11
0.00
40.00
0.00
12,503
629.24
0.10
0.10
0.00
45.00
0.00
10,747
629.07
0.09
0.09
0.00
50.00
0.00
9,118
628.92
0.08
0.08
0.00
55.00
0.00
7,711
628.78
0.07
0.07
0.00
60.00
0.00
6,514
628.67
0.06
0.06
0.00
65.00
0.00
5,496
628.57
0.05
0.05
0.00
70.00
0.00
4,633
628.48
0.04
0.04
0.00
75.00
0.00
3,902
628.41
0.04
0.04
0.00
80.00
0.00
3,284
628.34
0.03
0.03
0.00
85.00
0.00
2,762
628.29
0.03
0.03
0.00
90.00
0.00
2,322
628.24
0.02
0.02
0.00
95.00
0.00
1,951
628.21
0.02
0.02
0.00
100.00
0.00
1,639
628.17
0.02
0.02
0.00
105.00
0.00
1,376
628.15
0.01
0.01
0.00
110.00
0.00
1,155
628.12
0.01
0.01
0.00
115.00
0.00
969
628.10
0.01
0.01
0.00
120.00
0.00
813
628.09
0.01
0.01
0.00
125.00
0.00
682
628.07
0.01
0.01
0.00
130.00
0.00
572
628.06
0.01
0.01
0.00
135.00
0.00
480
628.05
0.00
0.00
0.00
140.00
0.00
403
628.04
0.00
0.00
0.00
145.00
0.00
338
628.04
0.00
0.00
0.00
150.00
0.00
283
628.03
0.00
0.00
0.00
155.00
0.00
238
628.03
0.00
0.00
0.00
160.00
0.00
199
628.02
0.00
0.00
0.00
165.00
0.00
167
628.02
0.00
0.00
0.00
170.00
0.00
140
628.01
0.00
0.00
0.00
175.00
0.00
118
628.01
0.00
0.00
0.00
180.00
0.00
99
628.01
0.00
0.00
0.00
185.00
0.00
83
628.01
0.00
0.00
0.00
190.00
0.00
69
628.01
0.00
0.00
0.00
195.00
0.00
58
628.01
0.00
0.00
0.00
200.00
0.00
49
628.01
0.00
0.00
0.00

2020.17-BM P3
Type 11 24-hr 10-yr Concord Rainfall=5.10"
Prepared by {enter your company name here} Page 19
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Stage -Discharge for Pond 3P: (BMP3)
Elevation Discharge Primary Secondary
(feet)
(cfs)
(cfs)
(cfs)
628.00
0.00
0.00
0.00
628.10
0.01
0.01
0.00
628.20
0.02
0.02
0.00
628.30
0.03
0.03
0.00
628.40
0.04
0.04
0.00
628.50
0.05
0.05
0.00
628.60
0.06
0.06
0.00
628.70
0.06
0.06
0.00
628.80
0.07
0.07
0.00
628.90
0.08
0.08
0.00
629.00
0.09
0.09
0.00
629.10
0.10
0.10
0.00
629.20
0.10
0.10
0.00
629.30
0.10
0.10
0.00
629.40
0.11
0.11
0.00
629.50
0.11
0.11
0.00
629.60
0.14
0.14
0.00
629.70
0.23
0.23
0.00
629.80
0.35
0.35
0.00
629.90
0.49
0.49
0.00
630.00
0.60
0.60
0.00
630.10
0.69
0.69
0.00
630.20
0.77
0.77
0.00
630.30
0.84
0.84
0.00
630.40
0.91
0.91
0.00
630.50
0.97
0.97
0.00
630.60
1.02
1.02
0.00
630.70
1.08
1.08
0.00
630.80
1.13
1.13
0.00
630.90
1.18
1.18
0.00
631.00
1.22
1.22
0.00
631.10
1.27
1.27
0.00
631.20
1.31
1.31
0.00
631.30
1.35
1.35
0.00
631.40
1.39
1.39
0.00
631.50
1.43
1.43
0.00
631.60
1.47
1.47
0.00
631.70
1.51
1.51
0.00
631.80
1.55
1.55
0.00
631.90
1.58
1.58
0.00
632.00
1.62
1.62
0.00
632.10
2.69
2.69
0.00
632.20
4.61
4.61
0.00
632.30
7.10
7.10
0.00
632.40
10.03
10.03
0.00
632.50
13.35
13.35
0.00
632.60
17.02
17.02
0.00
632.70
21.00
21.00
0.00
632.80
25.28
25.28
0.00
632.90
29.32
29.32
0.00
633.00
30.83
30.83
0.00
633.10
33.12
32.27
0.85
Elevation Discharge Primary Secondary
(feet)
(cfs)
(cfs)
(cfs)
633.20
36.05
33.65
2.40
633.30
39.39
34.97
4.42
633.40
43.07
36.24
6.83
633.50
46.21
36.67
9.55
633.60
49.31
36.77
12.55
633.70
52.50
36.86
15.64
633.80
55.85
36.96
18.89
633.90
59.56
37.06
22.50
634.00
63.46
37.16
26.30

2020.17-BM P3
Type // 24-hr 10-yr Concord Rainfall=5.10"
Prepared by {enter your company name here} Page 20
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Stage -Area -Storage for Pond 3P: (BMP3)
Elevation
Surface
Storage
(feet)
(sq-ft)
(cubic -feet)
628.00
9,379
0
628.10
9,498
944
628.20
9,618
1,900
628.30
9,737
2,867
628.40
9,857
3,847
628.50
9,976
4,839
628.60
10,096
5,842
628.70
10,215
6,858
628.80
10,335
7,885
628.90
10,454
8,925
629.00
10,574
9,976
629.10
10,693
11,040
629.20
10,812
12,115
629.30
10,932
13,202
629.40
11,051
14,301
629.50
11,171
15,412
629.60
11,290
16,535
629.70
11,410
17,670
629.80
11,529
18,817
629.90
11,649
19,976
630.00
11,768
21,147
630.10
11,899
22,330
630.20
12,029
23,527
630.30
12,160
24,736
630.40
12,291
25,959
630.50
12,421
27,194
630.60
12,552
28,443
630.70
12,683
29,705
630.80
12,813
30,979
630.90
12,944
32,267
631.00
13,075
33,568
631.10
13,205
34,882
631.20
13,336
36,209
631.30
13,466
37,549
631.40
13,597
38,903
631.50
13,728
40,269
631.60
13,858
41,648
631.70
13,989
43,040
631.80
14,120
44,446
631.90
14,250
45,864
632.00
14,381
47,296
632.10
14,523
48,741
632.20
14,665
50,201
632.30
14,807
51,674
632.40
14,949
53,162
632.50
15,091
54,664
632.60
15,233
56,180
632.70
15,375
57,711
632.80
15,517
59,255
632.90
15,659
60,814
633.00
15,802
62,387
633.10
15,944
63,975
Elevation
Surface
Storage
(feet)
(sq-ft)
(cubic -feet)
633.20
16,086
65,576
633.30
16,228
67,192
633.40
16,370
68,821
633.50
16,512
70,466
633.60
16,654
72,124
633.70
16,796
73,796
633.80
16,938
75,483
633.90
17,080
77,184
634.00
17,222
78,899

2020.17-BM P3 Type/1 24-hr 25-yr Concord Rainfall=6.00"
Prepared by {enter your company name here} Page 21
HvdroCAD® 8.00 s/n 004317 © 2006 HvdroCAD Software Solutions LLC 6/5/2022
Time span=0.00-200.00 hrs, dt=0.01 hrs, 20001 points
Runoff by SCS TR-20 method, UH=SCS
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment 1S: (Predeveloped) Runoff Area=8.870 ac Runoff Depth=2.44"
Flow Length=568' Tc=17.1 min CN=66 Runoff=25.90 cfs 1.804 of
Subcatchment 2S: (Post Developed) Runoff Area=8.870 ac Runoff Depth=3.38"
Tc=5.0 min CN=76 Runoff=55.04 cfs 2.498 of
Pond 3P: (BMP3) Peak Elev=632.38' Storage=52,803 cf Inflow=55.04 cfs 2.498 of
Primary=9.29 cfs 2.497 of Secondary=0.00 cfs 0.000 of Outflow=9.29 cfs 2.497 of
Total Runoff Area = 17.740 ac Runoff Volume = 4.302 of Average Runoff Depth = 2.91"
100.00% Pervious Area = 17.740 ac 0.00% Impervious Area = 0.000 ac

2020.17-BM P3
Type/1 24-hr 25-yr Concord Rainfall=6.00"
Prepared by {enter your company name here} Page 22
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Subcatchment 1S: (Predeveloped)
BASED ON EXISTING CONDITIONS
Runoff = 25.90 cfs @ 12.10 hrs, Volume= 1.804 af, Depth= 2.44"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Type II 24-hr 25-yr Concord Rainfall=6.00"
Area (ac)
CN
Description
4.340
60
Woods, Fair, HSG B
0.900
73
Woods, Fair, HSG C
1.090
79
Pasture/grassland/range, Fair, HSG C
2.540
69
Pasture/grassland/range, Fair, HSG B
8.870
66
Weighted Average
8.870
Pervious Area
Tc
Length
Slope
Velocity
Capacity Description
(min)
(feet)
(ft/ft)
(ft/sec)
(cfs)
11.8
100
0.0288
0.14
Sheet Flow,
Grass: Dense n= 0.240 P2= 3.50"
5.3
468
0.0880
1.48
Shallow Concentrated Flow,
Woodland Kv= 5.0 fps
17.1 568 Total

2020.17-BM P3
Type // 24-hr 25-yr Concord Rainfall=6.00"
Prepared by {enter your company name here} Page 23
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Hydrograph for Subcatchment 1S: (Predeveloped)
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
0.00
0.00
0.00
0.00
2.00
0.13
0.00
0.00
4.00
0.29
0.00
0.00
6.00
0.48
0.00
0.00
8.00
0.72
0.00
0.00
10.00
1.09
0.00
0.01
12.00
3.98
1.07
18.60
14.00
4.92
1.67
1.52
16.00
5.28
1.92
0.93
18.00
5.53
2.10
0.71
20.00
5.71
2.23
0.53
22.00
5.86
2.34
0.48
24.00
6.00
2.44
0.44
26.00
6.00
2.44
0.00
28.00
6.00
2.44
0.00
30.00
6.00
2.44
0.00
32.00
6.00
2.44
0.00
34.00
6.00
2.44
0.00
36.00
6.00
2.44
0.00
38.00
6.00
2.44
0.00
40.00
6.00
2.44
0.00
42.00
6.00
2.44
0.00
44.00
6.00
2.44
0.00
46.00
6.00
2.44
0.00
48.00
6.00
2.44
0.00
50.00
6.00
2.44
0.00
52.00
6.00
2.44
0.00
54.00
6.00
2.44
0.00
56.00
6.00
2.44
0.00
58.00
6.00
2.44
0.00
60.00
6.00
2.44
0.00
62.00
6.00
2.44
0.00
64.00
6.00
2.44
0.00
66.00
6.00
2.44
0.00
68.00
6.00
2.44
0.00
70.00
6.00
2.44
0.00
72.00
6.00
2.44
0.00
74.00
6.00
2.44
0.00
76.00
6.00
2.44
0.00
78.00
6.00
2.44
0.00
80.00
6.00
2.44
0.00
82.00
6.00
2.44
0.00
84.00
6.00
2.44
0.00
86.00
6.00
2.44
0.00
88.00
6.00
2.44
0.00
90.00
6.00
2.44
0.00
92.00
6.00
2.44
0.00
94.00
6.00
2.44
0.00
96.00
6.00
2.44
0.00
98.00
6.00
2.44
0.00
100.00
6.00
2.44
0.00
102.00
6.00
2.44
0.00
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
104.00
6.00
2.44
0.00
106.00
6.00
2.44
0.00
108.00
6.00
2.44
0.00
110.00
6.00
2.44
0.00
112.00
6.00
2.44
0.00
114.00
6.00
2.44
0.00
116.00
6.00
2.44
0.00
118.00
6.00
2.44
0.00
120.00
6.00
2.44
0.00
122.00
6.00
2.44
0.00
124.00
6.00
2.44
0.00
126.00
6.00
2.44
0.00
128.00
6.00
2.44
0.00
130.00
6.00
2.44
0.00
132.00
6.00
2.44
0.00
134.00
6.00
2.44
0.00
136.00
6.00
2.44
0.00
138.00
6.00
2.44
0.00
140.00
6.00
2.44
0.00
142.00
6.00
2.44
0.00
144.00
6.00
2.44
0.00
146.00
6.00
2.44
0.00
148.00
6.00
2.44
0.00
150.00
6.00
2.44
0.00
152.00
6.00
2.44
0.00
154.00
6.00
2.44
0.00
156.00
6.00
2.44
0.00
158.00
6.00
2.44
0.00
160.00
6.00
2.44
0.00
162.00
6.00
2.44
0.00
164.00
6.00
2.44
0.00
166.00
6.00
2.44
0.00
168.00
6.00
2.44
0.00
170.00
6.00
2.44
0.00
172.00
6.00
2.44
0.00
174.00
6.00
2.44
0.00
176.00
6.00
2.44
0.00
178.00
6.00
2.44
0.00
180.00
6.00
2.44
0.00
182.00
6.00
2.44
0.00
184.00
6.00
2.44
0.00
186.00
6.00
2.44
0.00
188.00
6.00
2.44
0.00
190.00
6.00
2.44
0.00
192.00
6.00
2.44
0.00
194.00
6.00
2.44
0.00
196.00
6.00
2.44
0.00
198.00
6.00
2.44
0.00
200.00
6.00
2.44
0.00

2020.17-BM P3 Type/1 24-hr 25-yr Concord Rainfall=6.00"
Prepared by {enter your company name here} Page 24
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Subcatchment 2S: (Post Developed)
Runoff = 55.04 cfs @ 11.96 hrs, Volume= 2.498 af, Depth= 3.38"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Type II 24-hr 25-yr Concord Rainfall=6.00"
Area (ac) CN
Description
1.630 83
RM-2 (C)
7.240 75
RM-2 (B)
8.870 76
Weighted Average
8.870
Pervious Area
Tc Length
Slope Velocity Capacity Description
(min) (feet)
(ft/ft) (ft/sec) (cfs)
5.0
Direct Entry,

2020.17-BM P3
Type // 24-hr 25-yr Concord Rainfall=6.00"
Prepared by {enter your company name here} Page 25
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Hydrograph for Subcatchment 2S: (Post Developed)
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
0.00
0.00
0.00
0.00
2.00
0.13
0.00
0.00
4.00
0.29
0.00
0.00
6.00
0.48
0.00
0.00
8.00
0.72
0.00
0.06
10.00
1.09
0.06
0.47
12.00
3.98
1.72
47.09
14.00
4.92
2.47
1.69
16.00
5.28
2.77
1.06
18.00
5.53
2.97
0.83
20.00
5.71
3.13
0.60
22.00
5.86
3.26
0.55
24.00
6.00
3.38
0.51
26.00
6.00
3.38
0.00
28.00
6.00
3.38
0.00
30.00
6.00
3.38
0.00
32.00
6.00
3.38
0.00
34.00
6.00
3.38
0.00
36.00
6.00
3.38
0.00
38.00
6.00
3.38
0.00
40.00
6.00
3.38
0.00
42.00
6.00
3.38
0.00
44.00
6.00
3.38
0.00
46.00
6.00
3.38
0.00
48.00
6.00
3.38
0.00
50.00
6.00
3.38
0.00
52.00
6.00
3.38
0.00
54.00
6.00
3.38
0.00
56.00
6.00
3.38
0.00
58.00
6.00
3.38
0.00
60.00
6.00
3.38
0.00
62.00
6.00
3.38
0.00
64.00
6.00
3.38
0.00
66.00
6.00
3.38
0.00
68.00
6.00
3.38
0.00
70.00
6.00
3.38
0.00
72.00
6.00
3.38
0.00
74.00
6.00
3.38
0.00
76.00
6.00
3.38
0.00
78.00
6.00
3.38
0.00
80.00
6.00
3.38
0.00
82.00
6.00
3.38
0.00
84.00
6.00
3.38
0.00
86.00
6.00
3.38
0.00
88.00
6.00
3.38
0.00
90.00
6.00
3.38
0.00
92.00
6.00
3.38
0.00
94.00
6.00
3.38
0.00
96.00
6.00
3.38
0.00
98.00
6.00
3.38
0.00
100.00
6.00
3.38
0.00
102.00
6.00
3.38
0.00
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
104.00
6.00
3.38
0.00
106.00
6.00
3.38
0.00
108.00
6.00
3.38
0.00
110.00
6.00
3.38
0.00
112.00
6.00
3.38
0.00
114.00
6.00
3.38
0.00
116.00
6.00
3.38
0.00
118.00
6.00
3.38
0.00
120.00
6.00
3.38
0.00
122.00
6.00
3.38
0.00
124.00
6.00
3.38
0.00
126.00
6.00
3.38
0.00
128.00
6.00
3.38
0.00
130.00
6.00
3.38
0.00
132.00
6.00
3.38
0.00
134.00
6.00
3.38
0.00
136.00
6.00
3.38
0.00
138.00
6.00
3.38
0.00
140.00
6.00
3.38
0.00
142.00
6.00
3.38
0.00
144.00
6.00
3.38
0.00
146.00
6.00
3.38
0.00
148.00
6.00
3.38
0.00
150.00
6.00
3.38
0.00
152.00
6.00
3.38
0.00
154.00
6.00
3.38
0.00
156.00
6.00
3.38
0.00
158.00
6.00
3.38
0.00
160.00
6.00
3.38
0.00
162.00
6.00
3.38
0.00
164.00
6.00
3.38
0.00
166.00
6.00
3.38
0.00
168.00
6.00
3.38
0.00
170.00
6.00
3.38
0.00
172.00
6.00
3.38
0.00
174.00
6.00
3.38
0.00
176.00
6.00
3.38
0.00
178.00
6.00
3.38
0.00
180.00
6.00
3.38
0.00
182.00
6.00
3.38
0.00
184.00
6.00
3.38
0.00
186.00
6.00
3.38
0.00
188.00
6.00
3.38
0.00
190.00
6.00
3.38
0.00
192.00
6.00
3.38
0.00
194.00
6.00
3.38
0.00
196.00
6.00
3.38
0.00
198.00
6.00
3.38
0.00
200.00
6.00
3.38
0.00

2020.17-BM P3 Type/1 24-hr 25-yr Concord Rainfall=6.00"
Prepared by {enter your company name here} Page 26
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Pond 3P: (BMP3)
Inflow Area = 8.870 ac, Inflow Depth = 3.38" for 25-yr Concord event
Inflow =
55.04 cfs @
11.96 hrs,
Volume=
2.498 of
Outflow =
9.29 cfs @
12.13 hrs,
Volume=
2.497 af, Atten= 83%, Lag= 10.3 min
Primary =
9.29 cfs @
12.13 hrs,
Volume=
2.497 of
Secondary =
0.00 cfs @
0.00 hrs,
Volume=
0.000 of
Routing by Stor-Ind method, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Peak Elev= 632.38' @ 12.13 hrs Surf.Area= 14,915 sf Storage= 52,803 cf
Plug -Flow detention time= 632.8 min calculated for 2.497 of (100% of inflow)
Center -of -Mass det. time= 633.0 min ( 1,453.0 - 820.0 )
Volume Invert Avail.Storage Storage Description
#1 628.00' 78,899 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic -feet) (cubic -feet)
628.00 9,379 0 0
630.00 11,768 21,147 21,147
632.00 14,381 26,149 47,296
634.00 17,222 31,603 78,899
Device Routing Invert Outlet Devices
#1 Primary 614.18' 18.0" x 30.0' long Culvert RCP, square edge headwall, Ke= 0.500
Outlet Invert= 614.00' S= 0.0060 7' Cc= 0.900 n= 0.013
#2 Device 1 628.00' Exfiltration
Head (feet) 0.00 1.00 2.00 3.00 4.00 5.00 6.00
Disch. (cfs) 0.000 0.092 0.128 0.165 0.202 0.239 0.275
#3 Device 1 629.50' 6.0" Vert. Orifice/Grate C= 0.600
#4 Device 1 632.00' 2.00' x 3.00' Horiz. Top of Riser Limited to weir flow C= 0.600
#5 Secondary 633.00' 10.0' long x 16.0' breadth Spillway
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Coef. (English) 2.68 2.70 2.70 2.64 2.63 2.64 2.64 2.63
Primary OutFlow Max=9.28 cfs @ 12.13 hrs HW=632.38' (Free Discharge)
L1=Culvert (Passes 9.28 cfs of 35.54 cfs potential flow)
2=Exfltration (Custom Controls 0.22 cfs)
3=Orifice/Grate (Orifice Controls 1.53 cfs @ 7.80 fps)
=Top of Riser (Weir Controls 7.53 cfs @ 2.00 fps)
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=628.00' (Free Discharge)
5=Spillway ( Controls 0.00 cfs)

2020.17-BM P3
Type // 24-hr 25-yr Concord Rainfall=6.00"
Prepared by {enter your company name here} Page 27
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Hydrograph for Pond 3P: (BMP3)
Time
Inflow
Storage
Elevation
Outflow
Primary
Secondary
(hours)
(cfs)
(cubic -feet)
(feet)
(cfs)
(cfs)
(cfs)
0.00
0.00
0
628.00
0.00
0.00
0.00
5.00
0.00
0
628.00
0.00
0.00
0.00
10.00
0.47
1,661
628.18
0.02
0.02
0.00
15.00
1.36
47,141
631.99
1.62
1.62
0.00
20.00
0.60
36,546
631.23
1.32
1.32
0.00
25.00
0.00
24,692
630.30
0.84
0.84
0.00
30.00
0.00
16,873
629.63
0.17
0.17
0.00
35.00
0.00
14,685
629.43
0.11
0.11
0.00
40.00
0.00
12,803
629.26
0.10
0.10
0.00
45.00
0.00
11,030
629.10
0.10
0.10
0.00
50.00
0.00
9,372
628.94
0.09
0.09
0.00
55.00
0.00
7,928
628.80
0.07
0.07
0.00
60.00
0.00
6,698
628.68
0.06
0.06
0.00
65.00
0.00
5,653
628.58
0.05
0.05
0.00
70.00
0.00
4,765
628.49
0.05
0.05
0.00
75.00
0.00
4,014
628.42
0.04
0.04
0.00
80.00
0.00
3,379
628.35
0.03
0.03
0.00
85.00
0.00
2,842
628.30
0.03
0.03
0.00
90.00
0.00
2,389
628.25
0.02
0.02
0.00
95.00
0.00
2,008
628.21
0.02
0.02
0.00
100.00
0.00
1,686
628.18
0.02
0.02
0.00
105.00
0.00
1,416
628.15
0.01
0.01
0.00
110.00
0.00
1,189
628.13
0.01
0.01
0.00
115.00
0.00
998
628.11
0.01
0.01
0.00
120.00
0.00
837
628.09
0.01
0.01
0.00
125.00
0.00
702
628.07
0.01
0.01
0.00
130.00
0.00
589
628.06
0.01
0.01
0.00
135.00
0.00
494
628.05
0.00
0.00
0.00
140.00
0.00
414
628.04
0.00
0.00
0.00
145.00
0.00
348
628.04
0.00
0.00
0.00
150.00
0.00
292
628.03
0.00
0.00
0.00
155.00
0.00
245
628.03
0.00
0.00
0.00
160.00
0.00
205
628.02
0.00
0.00
0.00
165.00
0.00
172
628.02
0.00
0.00
0.00
170.00
0.00
144
628.02
0.00
0.00
0.00
175.00
0.00
121
628.01
0.00
0.00
0.00
180.00
0.00
101
628.01
0.00
0.00
0.00
185.00
0.00
85
628.01
0.00
0.00
0.00
190.00
0.00
71
628.01
0.00
0.00
0.00
195.00
0.00
60
628.01
0.00
0.00
0.00
200.00
0.00
50
628.01
0.00
0.00
0.00

2020.17-BM P3
Type // 24-hr 25-yr Concord Rainfall=6.00"
Prepared by {enter your company name here} Page 28
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Stage -Discharge for Pond 3P: (BMP3)
Elevation Discharge Primary Secondary
(feet)
(cfs)
(cfs)
(cfs)
628.00
0.00
0.00
0.00
628.10
0.01
0.01
0.00
628.20
0.02
0.02
0.00
628.30
0.03
0.03
0.00
628.40
0.04
0.04
0.00
628.50
0.05
0.05
0.00
628.60
0.06
0.06
0.00
628.70
0.06
0.06
0.00
628.80
0.07
0.07
0.00
628.90
0.08
0.08
0.00
629.00
0.09
0.09
0.00
629.10
0.10
0.10
0.00
629.20
0.10
0.10
0.00
629.30
0.10
0.10
0.00
629.40
0.11
0.11
0.00
629.50
0.11
0.11
0.00
629.60
0.14
0.14
0.00
629.70
0.23
0.23
0.00
629.80
0.35
0.35
0.00
629.90
0.49
0.49
0.00
630.00
0.60
0.60
0.00
630.10
0.69
0.69
0.00
630.20
0.77
0.77
0.00
630.30
0.84
0.84
0.00
630.40
0.91
0.91
0.00
630.50
0.97
0.97
0.00
630.60
1.02
1.02
0.00
630.70
1.08
1.08
0.00
630.80
1.13
1.13
0.00
630.90
1.18
1.18
0.00
631.00
1.22
1.22
0.00
631.10
1.27
1.27
0.00
631.20
1.31
1.31
0.00
631.30
1.35
1.35
0.00
631.40
1.39
1.39
0.00
631.50
1.43
1.43
0.00
631.60
1.47
1.47
0.00
631.70
1.51
1.51
0.00
631.80
1.55
1.55
0.00
631.90
1.58
1.58
0.00
632.00
1.62
1.62
0.00
632.10
2.69
2.69
0.00
632.20
4.61
4.61
0.00
632.30
7.10
7.10
0.00
632.40
10.03
10.03
0.00
632.50
13.35
13.35
0.00
632.60
17.02
17.02
0.00
632.70
21.00
21.00
0.00
632.80
25.28
25.28
0.00
632.90
29.32
29.32
0.00
633.00
30.83
30.83
0.00
633.10
33.12
32.27
0.85
Elevation Discharge Primary Secondary
(feet)
(cfs)
(cfs)
(cfs)
633.20
36.05
33.65
2.40
633.30
39.39
34.97
4.42
633.40
43.07
36.24
6.83
633.50
46.21
36.67
9.55
633.60
49.31
36.77
12.55
633.70
52.50
36.86
15.64
633.80
55.85
36.96
18.89
633.90
59.56
37.06
22.50
634.00
63.46
37.16
26.30

2020.17-BM P3
Type // 24-hr 25-yr Concord Rainfall=6.00"
Prepared by {enter your company name here} Page 29
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Stage -Area -Storage for Pond 3P: (BMP3)
Elevation
Surface
Storage
(feet)
(sq-ft)
(cubic -feet)
628.00
9,379
0
628.10
9,498
944
628.20
9,618
1,900
628.30
9,737
2,867
628.40
9,857
3,847
628.50
9,976
4,839
628.60
10,096
5,842
628.70
10,215
6,858
628.80
10,335
7,885
628.90
10,454
8,925
629.00
10,574
9,976
629.10
10,693
11,040
629.20
10,812
12,115
629.30
10,932
13,202
629.40
11,051
14,301
629.50
11,171
15,412
629.60
11,290
16,535
629.70
11,410
17,670
629.80
11,529
18,817
629.90
11,649
19,976
630.00
11,768
21,147
630.10
11,899
22,330
630.20
12,029
23,527
630.30
12,160
24,736
630.40
12,291
25,959
630.50
12,421
27,194
630.60
12,552
28,443
630.70
12,683
29,705
630.80
12,813
30,979
630.90
12,944
32,267
631.00
13,075
33,568
631.10
13,205
34,882
631.20
13,336
36,209
631.30
13,466
37,549
631.40
13,597
38,903
631.50
13,728
40,269
631.60
13,858
41,648
631.70
13,989
43,040
631.80
14,120
44,446
631.90
14,250
45,864
632.00
14,381
47,296
632.10
14,523
48,741
632.20
14,665
50,201
632.30
14,807
51,674
632.40
14,949
53,162
632.50
15,091
54,664
632.60
15,233
56,180
632.70
15,375
57,711
632.80
15,517
59,255
632.90
15,659
60,814
633.00
15,802
62,387
633.10
15,944
63,975
Elevation
Surface
Storage
(feet)
(sq-ft)
(cubic -feet)
633.20
16,086
65,576
633.30
16,228
67,192
633.40
16,370
68,821
633.50
16,512
70,466
633.60
16,654
72,124
633.70
16,796
73,796
633.80
16,938
75,483
633.90
17,080
77,184
634.00
17,222
78,899

2020.17-BM P3 Type 11 24-hr 50-yr Concord Rainfall=6.80"
Prepared by {enter your company name here} Page 30
HvdroCAD® 8.00 s/n 004317 © 2006 HvdroCAD Software Solutions LLC 6/5/2022
Time span=0.00-200.00 hrs, dt=0.01 hrs, 20001 points
Runoff by SCS TR-20 method, UH=SCS
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment 1S: (Predeveloped) Runoff Area=8.870 ac Runoff Depth=3.05"
Flow Length=568' Tc=17.1 min CN=66 Runoff=32.62 cfs 2.253 of
Subcatchment 2S: (Post Developed) Runoff Area=8.870 ac Runoff Depth=4.08"
Tc=5.0 min CN=76 Runoff=65.94 cfs 3.016 of
Pond 3P: (BMP3) Peak Elev=632.80' Storage=59,259 cf Inflow=65.94 cfs 3.016 of
Primary=25.29 cfs 3.014 of Secondary=0.00 cfs 0.000 of Outflow=25.29 cfs 3.014 of
Total Runoff Area = 17.740 ac Runoff Volume = 5.269 of Average Runoff Depth = 3.56"
100.00% Pervious Area = 17.740 ac 0.00% Impervious Area = 0.000 ac

2020.17-BM P3
Type 11 24-hr 50-yr Concord Rainfall=6.80"
Prepared by {enter your company name here} Page 31
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Subcatchment 1S: (Predeveloped)
BASED ON EXISTING CONDITIONS
Runoff = 32.62 cfs @ 12.10 hrs, Volume= 2.253 af, Depth= 3.05"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Type II 24-hr 50-yr Concord Rainfall=6.80"
Area (ac)
CN
Description
4.340
60
Woods, Fair, HSG B
0.900
73
Woods, Fair, HSG C
1.090
79
Pasture/grassland/range, Fair, HSG C
2.540
69
Pasture/grassland/range, Fair, HSG B
8.870
66
Weighted Average
8.870
Pervious Area
Tc
Length
Slope
Velocity
Capacity Description
(min)
(feet)
(ft/ft)
(ft/sec)
(cfs)
11.8
100
0.0288
0.14
Sheet Flow,
Grass: Dense n= 0.240 P2= 3.50"
5.3
468
0.0880
1.48
Shallow Concentrated Flow,
Woodland Kv= 5.0 fps
17.1 568 Total

2020.17-BM P3
Type // 24-hr 50-yr Concord Rainfall=6.80"
Prepared by {enter your company name here} Page 32
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Hydrograph for Subcatchment 1S: (Predeveloped)
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
0.00
0.00
0.00
0.00
2.00
0.15
0.00
0.00
4.00
0.33
0.00
0.00
6.00
0.54
0.00
0.00
8.00
0.82
0.00
0.00
10.00
1.23
0.01
0.11
12.00
4.51
1.40
23.90
14.00
5.58
2.13
1.84
16.00
5.98
2.43
1.11
18.00
6.26
2.64
0.85
20.00
6.47
2.80
0.63
22.00
6.64
2.93
0.57
24.00
6.80
3.05
0.53
26.00
6.80
3.05
0.00
28.00
6.80
3.05
0.00
30.00
6.80
3.05
0.00
32.00
6.80
3.05
0.00
34.00
6.80
3.05
0.00
36.00
6.80
3.05
0.00
38.00
6.80
3.05
0.00
40.00
6.80
3.05
0.00
42.00
6.80
3.05
0.00
44.00
6.80
3.05
0.00
46.00
6.80
3.05
0.00
48.00
6.80
3.05
0.00
50.00
6.80
3.05
0.00
52.00
6.80
3.05
0.00
54.00
6.80
3.05
0.00
56.00
6.80
3.05
0.00
58.00
6.80
3.05
0.00
60.00
6.80
3.05
0.00
62.00
6.80
3.05
0.00
64.00
6.80
3.05
0.00
66.00
6.80
3.05
0.00
68.00
6.80
3.05
0.00
70.00
6.80
3.05
0.00
72.00
6.80
3.05
0.00
74.00
6.80
3.05
0.00
76.00
6.80
3.05
0.00
78.00
6.80
3.05
0.00
80.00
6.80
3.05
0.00
82.00
6.80
3.05
0.00
84.00
6.80
3.05
0.00
86.00
6.80
3.05
0.00
88.00
6.80
3.05
0.00
90.00
6.80
3.05
0.00
92.00
6.80
3.05
0.00
94.00
6.80
3.05
0.00
96.00
6.80
3.05
0.00
98.00
6.80
3.05
0.00
100.00
6.80
3.05
0.00
102.00
6.80
3.05
0.00
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
104.00
6.80
3.05
0.00
106.00
6.80
3.05
0.00
108.00
6.80
3.05
0.00
110.00
6.80
3.05
0.00
112.00
6.80
3.05
0.00
114.00
6.80
3.05
0.00
116.00
6.80
3.05
0.00
118.00
6.80
3.05
0.00
120.00
6.80
3.05
0.00
122.00
6.80
3.05
0.00
124.00
6.80
3.05
0.00
126.00
6.80
3.05
0.00
128.00
6.80
3.05
0.00
130.00
6.80
3.05
0.00
132.00
6.80
3.05
0.00
134.00
6.80
3.05
0.00
136.00
6.80
3.05
0.00
138.00
6.80
3.05
0.00
140.00
6.80
3.05
0.00
142.00
6.80
3.05
0.00
144.00
6.80
3.05
0.00
146.00
6.80
3.05
0.00
148.00
6.80
3.05
0.00
150.00
6.80
3.05
0.00
152.00
6.80
3.05
0.00
154.00
6.80
3.05
0.00
156.00
6.80
3.05
0.00
158.00
6.80
3.05
0.00
160.00
6.80
3.05
0.00
162.00
6.80
3.05
0.00
164.00
6.80
3.05
0.00
166.00
6.80
3.05
0.00
168.00
6.80
3.05
0.00
170.00
6.80
3.05
0.00
172.00
6.80
3.05
0.00
174.00
6.80
3.05
0.00
176.00
6.80
3.05
0.00
178.00
6.80
3.05
0.00
180.00
6.80
3.05
0.00
182.00
6.80
3.05
0.00
184.00
6.80
3.05
0.00
186.00
6.80
3.05
0.00
188.00
6.80
3.05
0.00
190.00
6.80
3.05
0.00
192.00
6.80
3.05
0.00
194.00
6.80
3.05
0.00
196.00
6.80
3.05
0.00
198.00
6.80
3.05
0.00
200.00
6.80
3.05
0.00

2020.17-BM P3 Type 11 24-hr 50-yr Concord Rainfall=6.80"
Prepared by {enter your company name here} Page 33
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Subcatchment 2S: (Post Developed)
Runoff = 65.94 cfs @ 11.96 hrs, Volume= 3.016 af, Depth= 4.08"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Type II 24-hr 50-yr Concord Rainfall=6.80"
Area (ac) CN
Description
1.630 83
RM-2 (C)
7.240 75
RM-2 (B)
8.870 76
Weighted Average
8.870
Pervious Area
Tc Length
Slope Velocity Capacity Description
(min) (feet)
(ft/ft) (ft/sec) (cfs)
5.0
Direct Entry,

2020.17-BM P3
Type // 24-hr 50-yr Concord Rainfall=6.80"
Prepared by {enter your company name here} Page 34
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Hydrograph for Subcatchment 2S: (Post Developed)
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
0.00
0.00
0.00
0.00
2.00
0.15
0.00
0.00
4.00
0.33
0.00
0.00
6.00
0.54
0.00
0.00
8.00
0.82
0.01
0.13
10.00
1.23
0.10
0.67
12.00
4.51
2.14
56.15
14.00
5.58
3.02
1.99
16.00
5.98
3.37
1.23
18.00
6.26
3.61
0.96
20.00
6.47
3.79
0.70
22.00
6.64
3.94
0.65
24.00
6.80
4.08
0.59
26.00
6.80
4.08
0.00
28.00
6.80
4.08
0.00
30.00
6.80
4.08
0.00
32.00
6.80
4.08
0.00
34.00
6.80
4.08
0.00
36.00
6.80
4.08
0.00
38.00
6.80
4.08
0.00
40.00
6.80
4.08
0.00
42.00
6.80
4.08
0.00
44.00
6.80
4.08
0.00
46.00
6.80
4.08
0.00
48.00
6.80
4.08
0.00
50.00
6.80
4.08
0.00
52.00
6.80
4.08
0.00
54.00
6.80
4.08
0.00
56.00
6.80
4.08
0.00
58.00
6.80
4.08
0.00
60.00
6.80
4.08
0.00
62.00
6.80
4.08
0.00
64.00
6.80
4.08
0.00
66.00
6.80
4.08
0.00
68.00
6.80
4.08
0.00
70.00
6.80
4.08
0.00
72.00
6.80
4.08
0.00
74.00
6.80
4.08
0.00
76.00
6.80
4.08
0.00
78.00
6.80
4.08
0.00
80.00
6.80
4.08
0.00
82.00
6.80
4.08
0.00
84.00
6.80
4.08
0.00
86.00
6.80
4.08
0.00
88.00
6.80
4.08
0.00
90.00
6.80
4.08
0.00
92.00
6.80
4.08
0.00
94.00
6.80
4.08
0.00
96.00
6.80
4.08
0.00
98.00
6.80
4.08
0.00
100.00
6.80
4.08
0.00
102.00
6.80
4.08
0.00
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
104.00
6.80
4.08
0.00
106.00
6.80
4.08
0.00
108.00
6.80
4.08
0.00
110.00
6.80
4.08
0.00
112.00
6.80
4.08
0.00
114.00
6.80
4.08
0.00
116.00
6.80
4.08
0.00
118.00
6.80
4.08
0.00
120.00
6.80
4.08
0.00
122.00
6.80
4.08
0.00
124.00
6.80
4.08
0.00
126.00
6.80
4.08
0.00
128.00
6.80
4.08
0.00
130.00
6.80
4.08
0.00
132.00
6.80
4.08
0.00
134.00
6.80
4.08
0.00
136.00
6.80
4.08
0.00
138.00
6.80
4.08
0.00
140.00
6.80
4.08
0.00
142.00
6.80
4.08
0.00
144.00
6.80
4.08
0.00
146.00
6.80
4.08
0.00
148.00
6.80
4.08
0.00
150.00
6.80
4.08
0.00
152.00
6.80
4.08
0.00
154.00
6.80
4.08
0.00
156.00
6.80
4.08
0.00
158.00
6.80
4.08
0.00
160.00
6.80
4.08
0.00
162.00
6.80
4.08
0.00
164.00
6.80
4.08
0.00
166.00
6.80
4.08
0.00
168.00
6.80
4.08
0.00
170.00
6.80
4.08
0.00
172.00
6.80
4.08
0.00
174.00
6.80
4.08
0.00
176.00
6.80
4.08
0.00
178.00
6.80
4.08
0.00
180.00
6.80
4.08
0.00
182.00
6.80
4.08
0.00
184.00
6.80
4.08
0.00
186.00
6.80
4.08
0.00
188.00
6.80
4.08
0.00
190.00
6.80
4.08
0.00
192.00
6.80
4.08
0.00
194.00
6.80
4.08
0.00
196.00
6.80
4.08
0.00
198.00
6.80
4.08
0.00
200.00
6.80
4.08
0.00

2020.17-BM P3 Type 11 24-hr 50-yr Concord Rainfall=6.80"
Prepared by {enter your company name here} Page 35
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Pond 3P: (BMP3)
Inflow Area = 8.870 ac, Inflow Depth = 4.08" for 50-yr Concord event
Inflow =
65.94 cfs @
11.96 hrs,
Volume=
3.016 of
Outflow =
25.29 cfs @
12.06 hrs,
Volume=
3.014 af, Atten= 62%, Lag= 6.0 min
Primary =
25.29 cfs @
12.06 hrs,
Volume=
3.014 of
Secondary =
0.00 cfs @
0.00 hrs,
Volume=
0.000 of
Routing by Stor-Ind method, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Peak Elev= 632.80' @ 12.06 hrs Surf.Area= 15,518 sf Storage= 59,259 cf
Plug -Flow detention time= 545.3 min calculated for 3.014 of (100% of inflow)
Center -of -Mass det. time= 545.1 min ( 1,359.7 - 814.6 )
Volume Invert Avail.Storage Storage Description
#1 628.00' 78,899 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic -feet) (cubic -feet)
628.00 9,379 0 0
630.00 11,768 21,147 21,147
632.00 14,381 26,149 47,296
634.00 17,222 31,603 78,899
Device Routing Invert Outlet Devices
#1 Primary 614.18' 18.0" x 30.0' long Culvert RCP, square edge headwall, Ke= 0.500
Outlet Invert= 614.00' S= 0.0060 7' Cc= 0.900 n= 0.013
#2 Device 1 628.00' Exfiltration
Head (feet) 0.00 1.00 2.00 3.00 4.00 5.00 6.00
Disch. (cfs) 0.000 0.092 0.128 0.165 0.202 0.239 0.275
#3 Device 1 629.50' 6.0" Vert. Orifice/Grate C= 0.600
#4 Device 1 632.00' 2.00' x 3.00' Horiz. Top of Riser Limited to weir flow C= 0.600
#5 Secondary 633.00' 10.0' long x 16.0' breadth Spillway
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Coef. (English) 2.68 2.70 2.70 2.64 2.63 2.64 2.64 2.63
Primary OutFlow Max=25.29 cfs @ 12.06 hrs HW=632.80' (Free Discharge)
L1=Culvert (Passes 25.29 cfs of 35.97 cfs potential flow)
2=Exfltration (Custom Controls 0.23 cfs)
3=Orifice/Grate (Orifice Controls 1.65 cfs @ 8.41 fps)
=Top of Riser (Weir Controls 23.41 cfs @ 2.93 fps)
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=628.00' (Free Discharge)
5=Spillway ( Controls 0.00 cfs)

2020.17-BM P3
Type // 24-hr 50-yr Concord Rainfall=6.80"
Prepared by {enter your company name here} Page 36
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Hydrograph for Pond 3P: (BMP3)
Time
Inflow
Storage
Elevation
Outflow
Primary
Secondary
(hours)
(cfs)
(cubic -feet)
(feet)
(cfs)
(cfs)
(cfs)
0.00
0.00
0
628.00
0.00
0.00
0.00
5.00
0.00
0
628.00
0.00
0.00
0.00
10.00
0.67
2,794
628.29
0.03
0.03
0.00
15.00
1.59
47,597
632.02
1.73
1.73
0.00
20.00
0.70
38,839
631.40
1.39
1.39
0.00
25.00
0.00
26,705
630.46
0.94
0.94
0.00
30.00
0.00
17,281
629.67
0.20
0.20
0.00
35.00
0.00
14,929
629.46
0.11
0.11
0.00
40.00
0.00
13,033
629.28
0.10
0.10
0.00
45.00
0.00
11,247
629.12
0.10
0.10
0.00
50.00
0.00
9,570
628.96
0.09
0.09
0.00
55.00
0.00
8,097
628.82
0.08
0.08
0.00
60.00
0.00
6,842
628.70
0.06
0.06
0.00
65.00
0.00
5,775
628.59
0.05
0.05
0.00
70.00
0.00
4,869
628.50
0.05
0.05
0.00
75.00
0.00
4,102
628.43
0.04
0.04
0.00
80.00
0.00
3,453
628.36
0.03
0.03
0.00
85.00
0.00
2,905
628.30
0.03
0.03
0.00
90.00
0.00
2,442
628.26
0.02
0.02
0.00
95.00
0.00
2,052
628.22
0.02
0.02
0.00
100.00
0.00
1,724
628.18
0.02
0.02
0.00
105.00
0.00
1,448
628.15
0.01
0.01
0.00
110.00
0.00
1,215
628.13
0.01
0.01
0.00
115.00
0.00
1,020
628.11
0.01
0.01
0.00
120.00
0.00
856
628.09
0.01
0.01
0.00
125.00
0.00
718
628.08
0.01
0.01
0.00
130.00
0.00
602
628.06
0.01
0.01
0.00
135.00
0.00
505
628.05
0.00
0.00
0.00
140.00
0.00
424
628.05
0.00
0.00
0.00
145.00
0.00
355
628.04
0.00
0.00
0.00
150.00
0.00
298
628.03
0.00
0.00
0.00
155.00
0.00
250
628.03
0.00
0.00
0.00
160.00
0.00
210
628.02
0.00
0.00
0.00
165.00
0.00
176
628.02
0.00
0.00
0.00
170.00
0.00
147
628.02
0.00
0.00
0.00
175.00
0.00
124
628.01
0.00
0.00
0.00
180.00
0.00
104
628.01
0.00
0.00
0.00
185.00
0.00
87
628.01
0.00
0.00
0.00
190.00
0.00
73
628.01
0.00
0.00
0.00
195.00
0.00
61
628.01
0.00
0.00
0.00
200.00
0.00
51
628.01
0.00
0.00
0.00

2020.17-BM P3
Type // 24-hr 50-yr Concord Rainfall=6.80"
Prepared by {enter your company name here} Page 37
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Stage -Discharge for Pond 3P: (BMP3)
Elevation Discharge Primary Secondary
(feet)
(cfs)
(cfs)
(cfs)
628.00
0.00
0.00
0.00
628.10
0.01
0.01
0.00
628.20
0.02
0.02
0.00
628.30
0.03
0.03
0.00
628.40
0.04
0.04
0.00
628.50
0.05
0.05
0.00
628.60
0.06
0.06
0.00
628.70
0.06
0.06
0.00
628.80
0.07
0.07
0.00
628.90
0.08
0.08
0.00
629.00
0.09
0.09
0.00
629.10
0.10
0.10
0.00
629.20
0.10
0.10
0.00
629.30
0.10
0.10
0.00
629.40
0.11
0.11
0.00
629.50
0.11
0.11
0.00
629.60
0.14
0.14
0.00
629.70
0.23
0.23
0.00
629.80
0.35
0.35
0.00
629.90
0.49
0.49
0.00
630.00
0.60
0.60
0.00
630.10
0.69
0.69
0.00
630.20
0.77
0.77
0.00
630.30
0.84
0.84
0.00
630.40
0.91
0.91
0.00
630.50
0.97
0.97
0.00
630.60
1.02
1.02
0.00
630.70
1.08
1.08
0.00
630.80
1.13
1.13
0.00
630.90
1.18
1.18
0.00
631.00
1.22
1.22
0.00
631.10
1.27
1.27
0.00
631.20
1.31
1.31
0.00
631.30
1.35
1.35
0.00
631.40
1.39
1.39
0.00
631.50
1.43
1.43
0.00
631.60
1.47
1.47
0.00
631.70
1.51
1.51
0.00
631.80
1.55
1.55
0.00
631.90
1.58
1.58
0.00
632.00
1.62
1.62
0.00
632.10
2.69
2.69
0.00
632.20
4.61
4.61
0.00
632.30
7.10
7.10
0.00
632.40
10.03
10.03
0.00
632.50
13.35
13.35
0.00
632.60
17.02
17.02
0.00
632.70
21.00
21.00
0.00
632.80
25.28
25.28
0.00
632.90
29.32
29.32
0.00
633.00
30.83
30.83
0.00
633.10
33.12
32.27
0.85
Elevation Discharge Primary Secondary
(feet)
(cfs)
(cfs)
(cfs)
633.20
36.05
33.65
2.40
633.30
39.39
34.97
4.42
633.40
43.07
36.24
6.83
633.50
46.21
36.67
9.55
633.60
49.31
36.77
12.55
633.70
52.50
36.86
15.64
633.80
55.85
36.96
18.89
633.90
59.56
37.06
22.50
634.00
63.46
37.16
26.30

2020.17-BM P3
Type // 24-hr 50-yr Concord Rainfall=6.80"
Prepared by {enter your company name here} Page 38
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Stage -Area -Storage for Pond 3P: (BMP3)
Elevation
Surface
Storage
(feet)
(sq-ft)
(cubic -feet)
628.00
9,379
0
628.10
9,498
944
628.20
9,618
1,900
628.30
9,737
2,867
628.40
9,857
3,847
628.50
9,976
4,839
628.60
10,096
5,842
628.70
10,215
6,858
628.80
10,335
7,885
628.90
10,454
8,925
629.00
10,574
9,976
629.10
10,693
11,040
629.20
10,812
12,115
629.30
10,932
13,202
629.40
11,051
14,301
629.50
11,171
15,412
629.60
11,290
16,535
629.70
11,410
17,670
629.80
11,529
18,817
629.90
11,649
19,976
630.00
11,768
21,147
630.10
11,899
22,330
630.20
12,029
23,527
630.30
12,160
24,736
630.40
12,291
25,959
630.50
12,421
27,194
630.60
12,552
28,443
630.70
12,683
29,705
630.80
12,813
30,979
630.90
12,944
32,267
631.00
13,075
33,568
631.10
13,205
34,882
631.20
13,336
36,209
631.30
13,466
37,549
631.40
13,597
38,903
631.50
13,728
40,269
631.60
13,858
41,648
631.70
13,989
43,040
631.80
14,120
44,446
631.90
14,250
45,864
632.00
14,381
47,296
632.10
14,523
48,741
632.20
14,665
50,201
632.30
14,807
51,674
632.40
14,949
53,162
632.50
15,091
54,664
632.60
15,233
56,180
632.70
15,375
57,711
632.80
15,517
59,255
632.90
15,659
60,814
633.00
15,802
62,387
633.10
15,944
63,975
Elevation
Surface
Storage
(feet)
(sq-ft)
(cubic -feet)
633.20
16,086
65,576
633.30
16,228
67,192
633.40
16,370
68,821
633.50
16,512
70,466
633.60
16,654
72,124
633.70
16,796
73,796
633.80
16,938
75,483
633.90
17,080
77,184
634.00
17,222
78,899

SAND FILTER-4
I 11 tl 1, Z7���-
_-
18" B A5O.S
u
-w-' fd'PFAP eexv � � y
11 ` ' . � flEAROVTS rrra.J
'AREA. }fM g

Mt. Pleasant, NC
Sand Filter Calculation
1. Calculate Runoff Coeff, (Rv)
Drainage area to filter, Ad =
Impervious area to filter forebay=
Impervious percentage =
Rv = 0.05 + 0.9(la) _
2. Calculate req'd water quality volume (WQV)
Brighton Park
4
9.56 ac
4.27 ac.
44.70%
0.45229088
Storage:
Cum
Elev.
Area
Vol.
Vol
631
10175
0
0
632
11544
10859.5
10859.5
634
14461
26005
36864.5
636
17604
32065
68929.5
638
21737
39341
108270.5
Calculate Depth for WQ Volume:
632
10859.5
632.37
15696
634
36864.5
Elevation of WQ Volume = 632.37
3. Convert Water Quality Volume, WQv to inches of runoff.
WQv = 1.0(Rv) = 0.45 inches
4. Site Hydrologic Input Parameters:
WQV = (Rv/1 x Ad/1 x 43560 sf/1 ac x Rd/1 x ft/12 in)
WQV = 15696 cf (used to size Af)
WQV= 0.3603 ac-ft.
Cn Pre = 76.0
Cn Post = 83.0 to pond

Table 4.8.3 Results of Hvdrolooic Calculations from HvdroCad
Condition
Q 1- ear
Q 10- r.
Q 25- r
Q 50 yr
Runoff
Pre Dev.
11.47
32.86
42.38
51.00
Post. Dev.
24.28
56.31
69.72
81.64
Routed
0.67
2.14
9.61
23.73
Peak Stage
633.5
636.04
636.38
636.83
Disch. Time
1125 Hours
1
1
11.2' Freeboard
Required
5. First 1/2 inch 0.40 ac-ft 17351.4 cf
Detain 18 hrs 64274 cf Provided
36 hrs 22374 cf
Release Peak-36 hrs 25047 cf Provided
6. Channel Protection Volume: CPv to be held for 24 hours + 12 hours = 36 hours
S = 1000/Cn-10 where Cn = 83.0
S = 2.05 inches
Compute total runoff for the 1-year, 24-hour storm event. Total rainfall depth is
Qd = (P-0.2S)^2/(P+0.8S) 2.9 1-year storm
Qd= 1.37 inches
Watershed Runoff = (Qd)(DA)(1 ft/12") = 1.09 ac-ft. = 1.065 per Hydro -CAD
From HydroCad- Max Release Rate = 0.67 cfs
From HydroCad: Maximum Stage: 633.5
Storage: 31153 cf
Drawdown Time: 125 Hours
7. Sedimentation Basin Surface Area
Min As=0.20xWQV= As= 3139 sf
8. Sand Filter Bed Surface Area (Af)
1448 sf
Af = (WQV x df)/(k x t x (ha + df) ha = average head
df = 1.5 (depth of filter media)
hmax = 1.37
OK
Calculate Ha = hmax/2 = 0.69 ft
Where df = depth of filter bed (25), k = permeability of sand (3.5), ha = avg depth, t=51 hrs=2.125 days
Af = 1448 sf 211.42 cf/hr = 0.0587289 cfs
hmax = 1.371948471 15696 cf/(As + Af)
Choose As + Af = 4587 sf
Per plan, As = 7555
Af = 3408
Total 10963 OK

9. Sand Filter Drawdown Calculation
Coeff. Of Permeability of filter media = 3.5ft/day = 0.146 ft/hr
Volume of water drained in one hour = 0.146 ft/hr x Af s.f. = 211.4241 cf/hour
Drawdown Time = WQV/Drawdown Rate = 74.24 hrs 3.093262 days
Underdrain Calculations:
78 I.f of underdrain shown; provide 6" perforated pvc pipe with 3/8" perforations spaces 3" o.c. - 4 longitudinal rows
spaced 90 degrees apart.
100 I.f. of pipe
100 I.f. x 4 rows/ft x 4 holes/ft =
50% of perforations =
Capacity of one hole =
1600 holes
800 holes
0.0083 cfs based upon CA(2gh)^0.5
Total Capacity = 6.64 cfs which is 113.1 times the capacity of the sand filter.
Total Capacityof 6" PVC @ 0.50% is 0.40 cfs (0.20 cfs assuming 50% clogged) from Mannings and BMP Manual.
10. Antiflotation Calculation
8 Height of Riser, ft.
6 Area of Riser, s.f.
48 Volume of Riser, c.f.
2995.2 Weight of Water @ 62.4 pcf
3294.72 Weight of water with safety factor of 1.1
82.6 Buoyant Wt. of Concrete = (145-62.4) pcf
1.48 Volume of Concrete Req'd in c.y.
39.89 Volume of Concrete Req'd in c.f.
48 Volume of Concrete in Structure (cf)
-8.11 Volume of Concrete Required (cf)
0.5 ft thick
2.8 Length/Width
(If negative, additional concrete weight not required)

Brighton Park
Mt. Pleasant, NC
1. Develop Stage -Discharge Data for Sand Filter Media.
From 4.8.18 of the BMP Standards Manual:
Q = Af(k)(h+df)/(df)
Latham -Walters Engineering, Inc.
16507-A Northcross Drive
Huntersville, NC 28078
where Af = surface area of filter bed = sf
df = filter bed depth, ft. = ft.
k = coefficient of permeability of filter media (ft/day) = ft/day
h = average height of water above filter bed (ft) 12, etc.
h
Q
cf/day
Q
cfs
1
8447.309
0.098
2
11826.23
0.137
3
15205.16
0.176
4
18584.08
0.215
5
21963
0.254
6
25341.93
0.293
7
28720.85
0.332
8
32099.77
0.372
9
35478.7
0.411
10
38857.62
0.450

is
(Predeveloped)
(Post Developed) (BMP-4)
Subcat Reach on Link

2020.17-BM P4
Prepared by {enter your company name here} Page 2
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Area Listing (all nodes)
Area (acres) CN Description (subcats)
4.920 73 Woods, Fair, HSG C (1 S)
4.640 79 Pasture/grassland/range, Fair, HSG C (1S)
9.560 83 RM-2 (C) (2S)
ii Lei Iwe]

2020.17-BMP4 Type 11 24-hr 1-yr Concord Rainfall=2.90"
Prepared by {enter your company name here} Page 3
HvdroCAD® 8.00 s/n 004317 © 2006 HvdroCAD Software Solutions LLC 6/5/2022
Time span=0.00-200.00 hrs, dt=0.01 hrs, 20001 points
Runoff by SCS TR-20 method, UH=SCS
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment 1S: (Predeveloped) Runoff Area=9.560 ac Runoff Depth=0.95"
Flow Length=512' Tc=14.6 min CN=76 Runoff=11.47 cfs 0.755 of
Subcatchment 2S: (Post Developed) Runoff Area=9.560 ac Runoff Depth=1.37"
Tc=5.0 min CN=83 Runoff=24.28 cfs 1.089 of
Pond 3P: (BMP-4) Peak Elev=633.50' Storage=29,879 cf Inflow=24.28 cfs 1.089 of
Primary=0.67 cfs 1.088 of Secondary=0.00 cfs 0.000 of Outflow=0.67 cfs 1.088 of
Total Runoff Area = 19.120 ac Runoff Volume = 1.844 of Average Runoff Depth = 1.16"
100.00% Pervious Area = 19.120 ac 0.00% Impervious Area = 0.000 ac

2020.17-BMP4 Type 11 24-hr 1-yr Concord Rainfall=2.90"
Prepared by {enter your company name here} Page 4
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Subcatchment 1S: (Predeveloped)
BASED ON EXISTING CONDITIONS
Runoff = 11.47 cfs @ 12.08 hrs, Volume= 0.755 af, Depth= 0.95"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Type II 24-hr 1-yr Concord Rainfall=2.90"
Area (ac) CN Description
4.920 73 Woods, Fair, HSG C
4.640 79 Pasture/grassland/range, Fair, HSG C
9.560 76 Weighted Average
9.560 Pervious Area
Tc
Length
Slope
Velocity
Capacity Description
(min)
(feet)
(ft/ft)
(ft/sec)
(cfs)
10.0
100
0.0439
0.17
Sheet Flow,
Grass: Dense n= 0.240 P2= 3.50"
4.6
412
0.0875
1.48
Shallow Concentrated Flow,
Woodland Kv= 5.0 fps
14.6 512 Total

2020.17-BM P4
Type // 24-hr 1-yr Concord Rainfall=2.90"
Prepared by {enter your company name here} Page 5
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Hydrograph for Subcatchment 1S: (Predeveloped)
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
0.00
0.00
0.00
0.00
2.00
0.06
0.00
0.00
4.00
0.14
0.00
0.00
6.00
0.23
0.00
0.00
8.00
0.35
0.00
0.00
10.00
0.52
0.00
0.00
12.00
1.92
0.37
8.95
14.00
2.38
0.62
0.67
16.00
2.55
0.73
0.42
18.00
2.67
0.80
0.33
20.00
2.76
0.86
0.24
22.00
2.83
0.90
0.22
24.00
2.90
0.95
0.21
26.00
2.90
0.95
0.00
28.00
2.90
0.95
0.00
30.00
2.90
0.95
0.00
32.00
2.90
0.95
0.00
34.00
2.90
0.95
0.00
36.00
2.90
0.95
0.00
38.00
2.90
0.95
0.00
40.00
2.90
0.95
0.00
42.00
2.90
0.95
0.00
44.00
2.90
0.95
0.00
46.00
2.90
0.95
0.00
48.00
2.90
0.95
0.00
50.00
2.90
0.95
0.00
52.00
2.90
0.95
0.00
54.00
2.90
0.95
0.00
56.00
2.90
0.95
0.00
58.00
2.90
0.95
0.00
60.00
2.90
0.95
0.00
62.00
2.90
0.95
0.00
64.00
2.90
0.95
0.00
66.00
2.90
0.95
0.00
68.00
2.90
0.95
0.00
70.00
2.90
0.95
0.00
72.00
2.90
0.95
0.00
74.00
2.90
0.95
0.00
76.00
2.90
0.95
0.00
78.00
2.90
0.95
0.00
80.00
2.90
0.95
0.00
82.00
2.90
0.95
0.00
84.00
2.90
0.95
0.00
86.00
2.90
0.95
0.00
88.00
2.90
0.95
0.00
90.00
2.90
0.95
0.00
92.00
2.90
0.95
0.00
94.00
2.90
0.95
0.00
96.00
2.90
0.95
0.00
98.00
2.90
0.95
0.00
100.00
2.90
0.95
0.00
102.00
2.90
0.95
0.00
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
104.00
2.90
0.95
0.00
106.00
2.90
0.95
0.00
108.00
2.90
0.95
0.00
110.00
2.90
0.95
0.00
112.00
2.90
0.95
0.00
114.00
2.90
0.95
0.00
116.00
2.90
0.95
0.00
118.00
2.90
0.95
0.00
120.00
2.90
0.95
0.00
122.00
2.90
0.95
0.00
124.00
2.90
0.95
0.00
126.00
2.90
0.95
0.00
128.00
2.90
0.95
0.00
130.00
2.90
0.95
0.00
132.00
2.90
0.95
0.00
134.00
2.90
0.95
0.00
136.00
2.90
0.95
0.00
138.00
2.90
0.95
0.00
140.00
2.90
0.95
0.00
142.00
2.90
0.95
0.00
144.00
2.90
0.95
0.00
146.00
2.90
0.95
0.00
148.00
2.90
0.95
0.00
150.00
2.90
0.95
0.00
152.00
2.90
0.95
0.00
154.00
2.90
0.95
0.00
156.00
2.90
0.95
0.00
158.00
2.90
0.95
0.00
160.00
2.90
0.95
0.00
162.00
2.90
0.95
0.00
164.00
2.90
0.95
0.00
166.00
2.90
0.95
0.00
168.00
2.90
0.95
0.00
170.00
2.90
0.95
0.00
172.00
2.90
0.95
0.00
174.00
2.90
0.95
0.00
176.00
2.90
0.95
0.00
178.00
2.90
0.95
0.00
180.00
2.90
0.95
0.00
182.00
2.90
0.95
0.00
184.00
2.90
0.95
0.00
186.00
2.90
0.95
0.00
188.00
2.90
0.95
0.00
190.00
2.90
0.95
0.00
192.00
2.90
0.95
0.00
194.00
2.90
0.95
0.00
196.00
2.90
0.95
0.00
198.00
2.90
0.95
0.00
200.00
2.90
0.95
0.00

2020.17-BM P4 Type 11 24-hr 1-yr Concord Rainfall=2.90"
Prepared by {enter your company name here} Page 6
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Subcatchment 2S: (Post Developed)
Runoff = 24.28 cfs @ 11.96 hrs, Volume= 1.089 af, Depth= 1.37"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Type II 24-hr 1-yr Concord Rainfall=2.90"
Area (ac) CN Description
9.560 83 RM-2 (C)
9.560 Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,

2020.17-BM P4
Type // 24-hr 1-yr Concord Rainfall=2.90"
Prepared by {enter your company name here} Page 7
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Hydrograph for Subcatchment 2S: (Post Developed)
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
0.00
0.00
0.00
0.00
2.00
0.06
0.00
0.00
4.00
0.14
0.00
0.00
6.00
0.23
0.00
0.00
8.00
0.35
0.00
0.00
10.00
0.52
0.01
0.10
12.00
1.92
0.64
21.05
14.00
2.38
0.96
0.80
16.00
2.55
1.10
0.50
18.00
2.67
1.19
0.39
20.00
2.76
1.26
0.29
22.00
2.83
1.31
0.27
24.00
2.90
1.37
0.25
26.00
2.90
1.37
0.00
28.00
2.90
1.37
0.00
30.00
2.90
1.37
0.00
32.00
2.90
1.37
0.00
34.00
2.90
1.37
0.00
36.00
2.90
1.37
0.00
38.00
2.90
1.37
0.00
40.00
2.90
1.37
0.00
42.00
2.90
1.37
0.00
44.00
2.90
1.37
0.00
46.00
2.90
1.37
0.00
48.00
2.90
1.37
0.00
50.00
2.90
1.37
0.00
52.00
2.90
1.37
0.00
54.00
2.90
1.37
0.00
56.00
2.90
1.37
0.00
58.00
2.90
1.37
0.00
60.00
2.90
1.37
0.00
62.00
2.90
1.37
0.00
64.00
2.90
1.37
0.00
66.00
2.90
1.37
0.00
68.00
2.90
1.37
0.00
70.00
2.90
1.37
0.00
72.00
2.90
1.37
0.00
74.00
2.90
1.37
0.00
76.00
2.90
1.37
0.00
78.00
2.90
1.37
0.00
80.00
2.90
1.37
0.00
82.00
2.90
1.37
0.00
84.00
2.90
1.37
0.00
86.00
2.90
1.37
0.00
88.00
2.90
1.37
0.00
90.00
2.90
1.37
0.00
92.00
2.90
1.37
0.00
94.00
2.90
1.37
0.00
96.00
2.90
1.37
0.00
98.00
2.90
1.37
0.00
100.00
2.90
1.37
0.00
102.00
2.90
1.37
0.00
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
104.00
2.90
1.37
0.00
106.00
2.90
1.37
0.00
108.00
2.90
1.37
0.00
110.00
2.90
1.37
0.00
112.00
2.90
1.37
0.00
114.00
2.90
1.37
0.00
116.00
2.90
1.37
0.00
118.00
2.90
1.37
0.00
120.00
2.90
1.37
0.00
122.00
2.90
1.37
0.00
124.00
2.90
1.37
0.00
126.00
2.90
1.37
0.00
128.00
2.90
1.37
0.00
130.00
2.90
1.37
0.00
132.00
2.90
1.37
0.00
134.00
2.90
1.37
0.00
136.00
2.90
1.37
0.00
138.00
2.90
1.37
0.00
140.00
2.90
1.37
0.00
142.00
2.90
1.37
0.00
144.00
2.90
1.37
0.00
146.00
2.90
1.37
0.00
148.00
2.90
1.37
0.00
150.00
2.90
1.37
0.00
152.00
2.90
1.37
0.00
154.00
2.90
1.37
0.00
156.00
2.90
1.37
0.00
158.00
2.90
1.37
0.00
160.00
2.90
1.37
0.00
162.00
2.90
1.37
0.00
164.00
2.90
1.37
0.00
166.00
2.90
1.37
0.00
168.00
2.90
1.37
0.00
170.00
2.90
1.37
0.00
172.00
2.90
1.37
0.00
174.00
2.90
1.37
0.00
176.00
2.90
1.37
0.00
178.00
2.90
1.37
0.00
180.00
2.90
1.37
0.00
182.00
2.90
1.37
0.00
184.00
2.90
1.37
0.00
186.00
2.90
1.37
0.00
188.00
2.90
1.37
0.00
190.00
2.90
1.37
0.00
192.00
2.90
1.37
0.00
194.00
2.90
1.37
0.00
196.00
2.90
1.37
0.00
198.00
2.90
1.37
0.00
200.00
2.90
1.37
0.00

2020.17-BM P4
Type 11 24-hr 1-yr Concord Rainfall=2.90"
Prepared by {enter your company name here} Page 8
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Pond 3P: (BMP-4)
Inflow Area = 9.560 ac, Inflow Depth = 1.37" for 1-yr Concord event
Inflow =
24.28 cfs @
11.96 hrs,
Volume=
1.089 of
Outflow =
0.67 cfs @
14.80 hrs,
Volume=
1.088 af, Atten= 97%, Lag= 170.2 min
Primary =
0.67 cfs @
14.80 hrs,
Volume=
1.088 of
Secondary =
0.00 cfs @
0.00 hrs,
Volume=
0.000 of
Routing by Stor-Ind method, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Peak Elev= 633.50' @ 14.80 hrs Surf.Area= 13,738 sf Storage= 29,879 cf
Plug -Flow detention time= 1,377.1 min calculated for 1.088 of (100% of inflow)
Center -of -Mass det. time= 1,376.8 min ( 2,210.3 - 833.5 )
Volume Invert
Avail.Storage Storage Description
#1 631.00'
108,271 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area
Inc.Store Cum.Store
(feet)
(sq-ft)
(cubic -feet) (cubic -feet)
631.00
10,175
0 0
632.00
11,544
10,860 10,860
634.00
14,461
26,005 36,865
636.00
17,604
32,065 68,930
638.00
21,737
39,341 108,271
Device Routing
Invert
Outlet Devices
#1 Primary
628.30'
18.0" x 58.5' long Culvert RCP, square edge headwall, Ke= 0.500
Outlet Invert= 628.00' S= 0.0051 T Cc= 0.900 n= 0.013
#2 Device 1
631.00'
Exfiltration
Head (feet) 0.00 1.00 2.00 3.00 4.00 5.00 6.00
Disch. (cfs) 0.000 0.120 0.168 0.216 0.264 0.312 0.360
#3 Device 1
633.00'
6.0" Vert. Orifice/Grate C= 0.600
#4 Device 1
636.00'
2.00' x 3.00' Horiz. Top of Riser Limited to weir flow C= 0.600
#5 Secondary
637.00'
10.0' long x 16.0' breadth Spillway
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Coef. (English) 2.68 2.70 2.70 2.64 2.63 2.64 2.64 2.63
Primary OutFlow Max=0.67 cfs @ 14.80 hrs HW=633.50' (Free Discharge)
L1=Culvert (Passes 0.67 cfs of 17.70 cfs potential flow)
2=Exfltration (Custom Controls 0.19 cfs)
3=Orifice/Grate (Orifice Controls 0.48 cfs @ 2.43 fps)
=Top of Riser ( Controls 0.00 cfs)
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=631.00' (Free Discharge)
5=Spillway ( Controls 0.00 cfs)

2020.17-BM P4
Type // 24-hr 1-yr Concord Rainfall=2.90"
Prepared by {enter your company name here} Page 9
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Hydrograph for Pond 3P: (BMP-4)
Time
Inflow
Storage
Elevation
Outflow
Primary
Secondary
(hours)
(cfs)
(cubic -feet)
(feet)
(cfs)
(cfs)
(cfs)
0.00
0.00
0
631.00
0.00
0.00
0.00
5.00
0.00
0
631.00
0.00
0.00
0.00
10.00
0.10
180
631.02
0.00
0.00
0.00
15.00
0.64
29,869
633.50
0.67
0.67
0.00
20.00
0.29
27,349
633.32
0.44
0.44
0.00
25.00
0.00
25,060
633.15
0.24
0.24
0.00
30.00
0.00
21,808
632.90
0.16
0.16
0.00
35.00
0.00
18,970
632.67
0.15
0.15
0.00
40.00
0.00
16,321
632.46
0.14
0.14
0.00
45.00
0.00
13,853
632.26
0.13
0.13
0.00
50.00
0.00
11,557
632.06
0.12
0.12
0.00
55.00
0.00
9,479
631.88
0.11
0.11
0.00
60.00
0.00
7,750
631.73
0.09
0.09
0.00
65.00
0.00
6,325
631.60
0.07
0.07
0.00
70.00
0.00
5,153
631.49
0.06
0.06
0.00
75.00
0.00
4,194
631.40
0.05
0.05
0.00
80.00
0.00
3,409
631.33
0.04
0.04
0.00
85.00
0.00
2,768
631.27
0.03
0.03
0.00
90.00
0.00
2,247
631.22
0.03
0.03
0.00
95.00
0.00
1,822
631.18
0.02
0.02
0.00
100.00
0.00
1,477
631.14
0.02
0.02
0.00
105.00
0.00
1,197
631.12
0.01
0.01
0.00
110.00
0.00
969
631.09
0.01
0.01
0.00
115.00
0.00
785
631.08
0.01
0.01
0.00
120.00
0.00
636
631.06
0.01
0.01
0.00
125.00
0.00
515
631.05
0.01
0.01
0.00
130.00
0.00
417
631.04
0.00
0.00
0.00
135.00
0.00
337
631.03
0.00
0.00
0.00
140.00
0.00
273
631.03
0.00
0.00
0.00
145.00
0.00
221
631.02
0.00
0.00
0.00
150.00
0.00
179
631.02
0.00
0.00
0.00
155.00
0.00
145
631.01
0.00
0.00
0.00
160.00
0.00
117
631.01
0.00
0.00
0.00
165.00
0.00
95
631.01
0.00
0.00
0.00
170.00
0.00
77
631.01
0.00
0.00
0.00
175.00
0.00
62
631.01
0.00
0.00
0.00
180.00
0.00
50
631.00
0.00
0.00
0.00
185.00
0.00
41
631.00
0.00
0.00
0.00
190.00
0.00
33
631.00
0.00
0.00
0.00
195.00
0.00
27
631.00
0.00
0.00
0.00
200.00
0.00
22
631.00
0.00
0.00
0.00

2020.17-BM P4
Type 11 24-hr 1-yr Concord Rainfall=2.90"
Prepared by {enter your company name here} Page 10
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Stage -Discharge for Pond 3P: (BMP-4)
Elevation Discharge Primary Secondary
(feet)
(cfs)
(cfs)
(cfs)
631.00
0.00
0.00
0.00
631.10
0.01
0.01
0.00
631.20
0.02
0.02
0.00
631.30
0.04
0.04
0.00
631.40
0.05
0.05
0.00
631.50
0.06
0.06
0.00
631.60
0.07
0.07
0.00
631.70
0.08
0.08
0.00
631.80
0.10
0.10
0.00
631.90
0.11
0.11
0.00
632.00
0.12
0.12
0.00
632.10
0.12
0.12
0.00
632.20
0.13
0.13
0.00
632.30
0.13
0.13
0.00
632.40
0.14
0.14
0.00
632.50
0.14
0.14
0.00
632.60
0.15
0.15
0.00
632.70
0.15
0.15
0.00
632.80
0.16
0.16
0.00
632.90
0.16
0.16
0.00
633.00
0.17
0.17
0.00
633.10
0.20
0.20
0.00
633.20
0.29
0.29
0.00
633.30
0.41
0.41
0.00
633.40
0.55
0.55
0.00
633.50
0.66
0.66
0.00
633.60
0.76
0.76
0.00
633.70
0.84
0.84
0.00
633.80
0.91
0.91
0.00
633.90
0.97
0.97
0.00
634.00
1.03
1.03
0.00
634.10
1.09
1.09
0.00
634.20
1.15
1.15
0.00
634.30
1.20
1.20
0.00
634.40
1.25
1.25
0.00
634.50
1.30
1.30
0.00
634.60
1.34
1.34
0.00
634.70
1.39
1.39
0.00
634.80
1.43
1.43
0.00
634.90
1.47
1.47
0.00
635.00
1.51
1.51
0.00
635.10
1.55
1.55
0.00
635.20
1.59
1.59
0.00
635.30
1.63
1.63
0.00
635.40
1.67
1.67
0.00
635.50
1.71
1.71
0.00
635.60
1.74
1.74
0.00
635.70
1.78
1.78
0.00
635.80
1.81
1.81
0.00
635.90
1.85
1.85
0.00
636.00
1.88
1.88
0.00
636.10
2.95
2.95
0.00
Elevation Discharge Primary Secondary
(feet)
(cfs)
(cfs)
(cfs)
636.20
4.87
4.87
0.00
636.30
7.35
7.35
0.00
636.40
10.28
10.28
0.00
636.50
13.60
13.60
0.00
636.60
17.27
17.27
0.00
636.70
21.25
21.25
0.00
636.80
23.69
23.69
0.00
636.90
23.84
23.84
0.00
637.00
23.99
23.99
0.00
637.10
24.99
24.14
0.85
637.20
26.69
24.29
2.40
637.30
28.86
24.44
4.42
637.40
31.42
24.59
6.83
637.50
34.28
24.73
9.55
637.60
37.43
24.88
12.55
637.70
40.66
25.03
15.64
637.80
44.06
25.17
18.89
637.90
47.81
25.31
22.50
638.00
51.76
25.46
26.30

2020.17-BM P4
Type 11 24-hr 1-yr Concord Rainfall=2.90"
Prepared by {enter your company name here} Page 11
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Stage -Area -Storage for Pond 3P: (BMP-4)
Elevation
Surface
Storage
(feet)
(sq-ft)
(cubic -feet)
631.00
10,175
0
631.10
10,312
1,024
631.20
10,449
2,062
631.30
10,586
3,114
631.40
10,723
4,180
631.50
10,860
5,259
631.60
10,996
6,351
631.70
11,133
7,458
631.80
11,270
8,578
631.90
11,407
9,712
632.00
11,544
10,860
632.10
11,690
12,021
632.20
11,836
13,197
632.30
11,982
14,388
632.40
12,127
15,594
632.50
12,273
16,814
632.60
12,419
18,048
632.70
12,565
19,298
632.80
12,711
20,561
632.90
12,857
21,840
633.00
13,003
23,133
633.10
13,148
24,440
633.20
13,294
25,762
633.30
13,440
27,099
633.40
13,586
28,450
633.50
13,732
29,816
633.60
13,878
31,197
633.70
14,023
32,592
633.80
14,169
34,001
633.90
14,315
35,426
634.00
14,461
36,865
634.10
14,618
38,318
634.20
14,775
39,788
634.30
14,932
41,274
634.40
15,090
42,775
634.50
15,247
44,291
634.60
15,404
45,824
634.70
15,561
47,372
634.80
15,718
48,936
634.90
15,875
50,516
635.00
16,033
52,111
635.10
16,190
53,722
635.20
16,347
55,349
635.30
16,504
56,992
635.40
16,661
58,650
635.50
16,818
60,324
635.60
16,975
62,014
635.70
17,133
63,719
635.80
17,290
65,440
635.90
17,447
67,177
636.00
17,604
68,930
636.10
17,811
70,700
Elevation
Surface
Storage
(feet)
(sq-ft)
(cubic -feet)
636.20
18,017
72,492
636.30
18,224
74,304
636.40
18,431
76,136
636.50
18,637
77,990
636.60
18,844
79,864
636.70
19,051
81,759
636.80
19,257
83,674
636.90
19,464
85,610
637.00
19,671
87,567
637.10
19,877
89,544
637.20
20,084
91,542
637.30
20,290
93,561
637.40
20,497
95,600
637.50
20,704
97,660
637.60
20,910
99,741
637.70
21,117
101,842
637.80
21,324
103,964
637.90
21,530
106,107
638.00
21,737
108,271

2020.17-BM P4 Type 11 24-hr 10-yr Concord Rainfall=5.10"
Prepared by {enter your company name here} Page 12
HvdroCAD® 8.00 s/n 004317 © 2006 HvdroCAD Software Solutions LLC 6/5/2022
Time span=0.00-200.00 hrs, dt=0.01 hrs, 20001 points
Runoff by SCS TR-20 method, UH=SCS
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment 1S: (Predeveloped) Runoff Area=9.560 ac Runoff Depth=2.62"
Flow Length=512' Tc=14.6 min CN=76 Runoff=32.86 cfs 2.086 of
Subcatchment 2S: (Post Developed) Runoff Area=9.560 ac Runoff Depth=3.26"
Tc=5.0 min CN=83 Runoff=56.31 cfs 2.601 of
Pond 3P: (BMP-4) Peak Elev=636.04' Storage=69,597 cf Inflow=56.31 cfs 2.601 of
Primary=2.14 cfs 2.600 of Secondary=0.00 cfs 0.000 of Outflow=2.14 cfs 2.600 of
Total Runoff Area = 19.120 ac Runoff Volume = 4.687 of Average Runoff Depth = 2.94"
100.00% Pervious Area = 19.120 ac 0.00% Impervious Area = 0.000 ac

2020.17-BM P4 Type 11 24-hr 10-yr Concord Rainfall=5.10"
Prepared by {enter your company name here} Page 13
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Subcatchment 1S: (Predeveloped)
BASED ON EXISTING CONDITIONS
Runoff = 32.86 cfs @ 12.07 hrs, Volume= 2.086 af, Depth= 2.62"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Type II 24-hr 10-yr Concord Rainfall=5.10"
Area (ac) CN Description
4.920 73 Woods, Fair, HSG C
4.640 79 Pasture/grassland/range, Fair, HSG C
9.560 76 Weighted Average
9.560 Pervious Area
Tc
Length
Slope
Velocity
Capacity Description
(min)
(feet)
(ft/ft)
(ft/sec)
(cfs)
10.0
100
0.0439
0.17
Sheet Flow,
Grass: Dense n= 0.240 P2= 3.50"
4.6
412
0.0875
1.48
Shallow Concentrated Flow,
Woodland Kv= 5.0 fps
14.6 512 Total

2020.17-BM P4
Type 11 24-hr 10-yr Concord Rainfall=5.10"
Prepared by {enter your company name here} Page 14
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Hydrograph for Subcatchment 1S: (Predeveloped)
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
0.00
0.00
0.00
0.00
2.00
0.11
0.00
0.00
4.00
0.24
0.00
0.00
6.00
0.41
0.00
0.00
8.00
0.61
0.00
0.00
10.00
0.92
0.02
0.25
12.00
3.38
1.28
27.56
14.00
4.18
1.88
1.58
16.00
4.49
2.12
0.96
18.00
4.70
2.29
0.74
20.00
4.86
2.42
0.54
22.00
4.98
2.52
0.49
24.00
5.10
2.62
0.45
26.00
5.10
2.62
0.00
28.00
5.10
2.62
0.00
30.00
5.10
2.62
0.00
32.00
5.10
2.62
0.00
34.00
5.10
2.62
0.00
36.00
5.10
2.62
0.00
38.00
5.10
2.62
0.00
40.00
5.10
2.62
0.00
42.00
5.10
2.62
0.00
44.00
5.10
2.62
0.00
46.00
5.10
2.62
0.00
48.00
5.10
2.62
0.00
50.00
5.10
2.62
0.00
52.00
5.10
2.62
0.00
54.00
5.10
2.62
0.00
56.00
5.10
2.62
0.00
58.00
5.10
2.62
0.00
60.00
5.10
2.62
0.00
62.00
5.10
2.62
0.00
64.00
5.10
2.62
0.00
66.00
5.10
2.62
0.00
68.00
5.10
2.62
0.00
70.00
5.10
2.62
0.00
72.00
5.10
2.62
0.00
74.00
5.10
2.62
0.00
76.00
5.10
2.62
0.00
78.00
5.10
2.62
0.00
80.00
5.10
2.62
0.00
82.00
5.10
2.62
0.00
84.00
5.10
2.62
0.00
86.00
5.10
2.62
0.00
88.00
5.10
2.62
0.00
90.00
5.10
2.62
0.00
92.00
5.10
2.62
0.00
94.00
5.10
2.62
0.00
96.00
5.10
2.62
0.00
98.00
5.10
2.62
0.00
100.00
5.10
2.62
0.00
102.00
5.10
2.62
0.00
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
104.00
5.10
2.62
0.00
106.00
5.10
2.62
0.00
108.00
5.10
2.62
0.00
110.00
5.10
2.62
0.00
112.00
5.10
2.62
0.00
114.00
5.10
2.62
0.00
116.00
5.10
2.62
0.00
118.00
5.10
2.62
0.00
120.00
5.10
2.62
0.00
122.00
5.10
2.62
0.00
124.00
5.10
2.62
0.00
126.00
5.10
2.62
0.00
128.00
5.10
2.62
0.00
130.00
5.10
2.62
0.00
132.00
5.10
2.62
0.00
134.00
5.10
2.62
0.00
136.00
5.10
2.62
0.00
138.00
5.10
2.62
0.00
140.00
5.10
2.62
0.00
142.00
5.10
2.62
0.00
144.00
5.10
2.62
0.00
146.00
5.10
2.62
0.00
148.00
5.10
2.62
0.00
150.00
5.10
2.62
0.00
152.00
5.10
2.62
0.00
154.00
5.10
2.62
0.00
156.00
5.10
2.62
0.00
158.00
5.10
2.62
0.00
160.00
5.10
2.62
0.00
162.00
5.10
2.62
0.00
164.00
5.10
2.62
0.00
166.00
5.10
2.62
0.00
168.00
5.10
2.62
0.00
170.00
5.10
2.62
0.00
172.00
5.10
2.62
0.00
174.00
5.10
2.62
0.00
176.00
5.10
2.62
0.00
178.00
5.10
2.62
0.00
180.00
5.10
2.62
0.00
182.00
5.10
2.62
0.00
184.00
5.10
2.62
0.00
186.00
5.10
2.62
0.00
188.00
5.10
2.62
0.00
190.00
5.10
2.62
0.00
192.00
5.10
2.62
0.00
194.00
5.10
2.62
0.00
196.00
5.10
2.62
0.00
198.00
5.10
2.62
0.00
200.00
5.10
2.62
0.00

2020.17-BM P4
Type 11 24-hr 10-yr Concord Rainfall=5.10"
Prepared by {enter your company name here} Page 15
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Subcatchment 2S: (Post Developed)
Runoff = 56.31 cfs @ 11.96 hrs, Volume= 2.601 af, Depth= 3.26"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Type II 24-hr 10-yr Concord Rainfall=5.10"
Area (ac) CN Description
9.560 83 RM-2 (C)
9.560 Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,

2020.17-BM P4
Type 11 24-hr 10-yr Concord Rainfall=5.10"
Prepared by {enter your company name here} Page 16
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Hydrograph for Subcatchment 2S: (Post Developed)
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
0.00
0.00
0.00
0.00
2.00
0.11
0.00
0.00
4.00
0.24
0.00
0.00
6.00
0.41
0.00
0.00
8.00
0.61
0.02
0.18
10.00
0.92
0.10
0.67
12.00
3.38
1.76
47.72
14.00
4.18
2.44
1.66
16.00
4.49
2.71
1.03
18.00
4.70
2.90
0.80
20.00
4.86
3.04
0.58
22.00
4.98
3.16
0.54
24.00
5.10
3.26
0.49
26.00
5.10
3.26
0.00
28.00
5.10
3.26
0.00
30.00
5.10
3.26
0.00
32.00
5.10
3.26
0.00
34.00
5.10
3.26
0.00
36.00
5.10
3.26
0.00
38.00
5.10
3.26
0.00
40.00
5.10
3.26
0.00
42.00
5.10
3.26
0.00
44.00
5.10
3.26
0.00
46.00
5.10
3.26
0.00
48.00
5.10
3.26
0.00
50.00
5.10
3.26
0.00
52.00
5.10
3.26
0.00
54.00
5.10
3.26
0.00
56.00
5.10
3.26
0.00
58.00
5.10
3.26
0.00
60.00
5.10
3.26
0.00
62.00
5.10
3.26
0.00
64.00
5.10
3.26
0.00
66.00
5.10
3.26
0.00
68.00
5.10
3.26
0.00
70.00
5.10
3.26
0.00
72.00
5.10
3.26
0.00
74.00
5.10
3.26
0.00
76.00
5.10
3.26
0.00
78.00
5.10
3.26
0.00
80.00
5.10
3.26
0.00
82.00
5.10
3.26
0.00
84.00
5.10
3.26
0.00
86.00
5.10
3.26
0.00
88.00
5.10
3.26
0.00
90.00
5.10
3.26
0.00
92.00
5.10
3.26
0.00
94.00
5.10
3.26
0.00
96.00
5.10
3.26
0.00
98.00
5.10
3.26
0.00
100.00
5.10
3.26
0.00
102.00
5.10
3.26
0.00
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
104.00
5.10
3.26
0.00
106.00
5.10
3.26
0.00
108.00
5.10
3.26
0.00
110.00
5.10
3.26
0.00
112.00
5.10
3.26
0.00
114.00
5.10
3.26
0.00
116.00
5.10
3.26
0.00
118.00
5.10
3.26
0.00
120.00
5.10
3.26
0.00
122.00
5.10
3.26
0.00
124.00
5.10
3.26
0.00
126.00
5.10
3.26
0.00
128.00
5.10
3.26
0.00
130.00
5.10
3.26
0.00
132.00
5.10
3.26
0.00
134.00
5.10
3.26
0.00
136.00
5.10
3.26
0.00
138.00
5.10
3.26
0.00
140.00
5.10
3.26
0.00
142.00
5.10
3.26
0.00
144.00
5.10
3.26
0.00
146.00
5.10
3.26
0.00
148.00
5.10
3.26
0.00
150.00
5.10
3.26
0.00
152.00
5.10
3.26
0.00
154.00
5.10
3.26
0.00
156.00
5.10
3.26
0.00
158.00
5.10
3.26
0.00
160.00
5.10
3.26
0.00
162.00
5.10
3.26
0.00
164.00
5.10
3.26
0.00
166.00
5.10
3.26
0.00
168.00
5.10
3.26
0.00
170.00
5.10
3.26
0.00
172.00
5.10
3.26
0.00
174.00
5.10
3.26
0.00
176.00
5.10
3.26
0.00
178.00
5.10
3.26
0.00
180.00
5.10
3.26
0.00
182.00
5.10
3.26
0.00
184.00
5.10
3.26
0.00
186.00
5.10
3.26
0.00
188.00
5.10
3.26
0.00
190.00
5.10
3.26
0.00
192.00
5.10
3.26
0.00
194.00
5.10
3.26
0.00
196.00
5.10
3.26
0.00
198.00
5.10
3.26
0.00
200.00
5.10
3.26
0.00

2020.17-BM P4
Type 11 24-hr 10-yr Concord Rainfall=5.10"
Prepared by {enter your company name here} Page 17
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Pond 3P: (BMP-4)
Inflow Area = 9.560 ac, Inflow Depth = 3.26" for 10-yr Concord event
Inflow =
56.31 cfs @
11.96 hrs,
Volume=
2.601 of
Outflow =
2.14 cfs @
13.47 hrs,
Volume=
2.600 af, Atten= 96%, Lag= 90.6 min
Primary =
2.14 cfs @
13.47 hrs,
Volume=
2.600 of
Secondary =
0.00 cfs @
0.00 hrs,
Volume=
0.000 of
Routing by Stor-Ind method, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Peak Elev= 636.04' @ 13.47 hrs Surf.Area= 17,682 sf Storage= 69,597 cf
Plug -Flow detention time= 869.1 min calculated for 2.600 of (100% of inflow)
Center -of -Mass det. time= 869.4 min ( 1,678.1 - 808.6 )
Volume Invert
Avail.Storage Storage Description
#1 631.00'
108,271 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area
Inc.Store Cum.Store
(feet)
(sq-ft)
(cubic -feet) (cubic -feet)
631.00
10,175
0 0
632.00
11,544
10,860 10,860
634.00
14,461
26,005 36,865
636.00
17,604
32,065 68,930
638.00
21,737
39,341 108,271
Device Routing
Invert
Outlet Devices
#1 Primary
628.30'
18.0" x 58.5' long Culvert RCP, square edge headwall, Ke= 0.500
Outlet Invert= 628.00' S= 0.0051 T Cc= 0.900 n= 0.013
#2 Device 1
631.00'
Exfiltration
Head (feet) 0.00 1.00 2.00 3.00 4.00 5.00 6.00
Disch. (cfs) 0.000 0.120 0.168 0.216 0.264 0.312 0.360
#3 Device 1
633.00'
6.0" Vert. Orifice/Grate C= 0.600
#4 Device 1
636.00'
2.00' x 3.00' Horiz. Top of Riser Limited to weir flow C= 0.600
#5 Secondary
637.00'
10.0' long x 16.0' breadth Spillway
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Coef. (English) 2.68 2.70 2.70 2.64 2.63 2.64 2.64 2.63
Primary OutFlow Max=2.13 cfs @ 13.47 hrs HW=636.04' (Free Discharge)
L1=Culvert (Passes 2.13 cfs of 22.49 cfs potential flow)
2=Exfltration (Custom Controls 0.31 cfs)
3=Orifice/Grate (Orifice Controls 1.58 cfs @ 8.04 fps)
=Top of Riser (Weir Controls 0.24 cfs @ 0.64 fps)
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=631.00' (Free Discharge)
5=Spillway ( Controls 0.00 cfs)

2020.17-BM P4
Type 11 24-hr 10-yr Concord Rainfall=5.10"
Prepared by {enter your company name here} Page 18
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Hydrograph for Pond 3P: (BMP-4)
Time
Inflow
Storage
Elevation
Outflow
Primary
Secondary
(hours)
(cfs)
(cubic -feet)
(feet)
(cfs)
(cfs)
(cfs)
0.00
0.00
0
631.00
0.00
0.00
0.00
5.00
0.00
0
631.00
0.00
0.00
0.00
10.00
0.67
3,228
631.31
0.04
0.04
0.00
15.00
1.33
67,736
635.93
1.86
1.86
0.00
20.00
0.58
52,705
635.04
1.53
1.53
0.00
25.00
0.00
36,986
634.01
1.04
1.04
0.00
30.00
0.00
25,569
633.19
0.28
0.28
0.00
35.00
0.00
22,133
632.92
0.16
0.16
0.00
40.00
0.00
19,274
632.70
0.15
0.15
0.00
45.00
0.00
16,604
632.48
0.14
0.14
0.00
50.00
0.00
14,116
632.28
0.13
0.13
0.00
55.00
0.00
11,802
632.08
0.12
0.12
0.00
60.00
0.00
9,691
631.90
0.11
0.11
0.00
65.00
0.00
7,925
631.74
0.09
0.09
0.00
70.00
0.00
6,468
631.61
0.07
0.07
0.00
75.00
0.00
5,271
631.50
0.06
0.06
0.00
80.00
0.00
4,290
631.41
0.05
0.05
0.00
85.00
0.00
3,488
631.34
0.04
0.04
0.00
90.00
0.00
2,833
631.27
0.03
0.03
0.00
95.00
0.00
2,299
631.22
0.03
0.03
0.00
100.00
0.00
1,865
631.18
0.02
0.02
0.00
105.00
0.00
1,512
631.15
0.02
0.02
0.00
110.00
0.00
1,225
631.12
0.01
0.01
0.00
115.00
0.00
992
631.10
0.01
0.01
0.00
120.00
0.00
804
631.08
0.01
0.01
0.00
125.00
0.00
651
631.06
0.01
0.01
0.00
130.00
0.00
527
631.05
0.01
0.01
0.00
135.00
0.00
426
631.04
0.01
0.01
0.00
140.00
0.00
345
631.03
0.00
0.00
0.00
145.00
0.00
279
631.03
0.00
0.00
0.00
150.00
0.00
226
631.02
0.00
0.00
0.00
155.00
0.00
183
631.02
0.00
0.00
0.00
160.00
0.00
148
631.01
0.00
0.00
0.00
165.00
0.00
120
631.01
0.00
0.00
0.00
170.00
0.00
97
631.01
0.00
0.00
0.00
175.00
0.00
79
631.01
0.00
0.00
0.00
180.00
0.00
64
631.01
0.00
0.00
0.00
185.00
0.00
52
631.01
0.00
0.00
0.00
190.00
0.00
42
631.00
0.00
0.00
0.00
195.00
0.00
34
631.00
0.00
0.00
0.00
200.00
0.00
27
631.00
0.00
0.00
0.00

2020.17-BM P4
Type 11 24-hr 10-yr Concord Rainfall=5.10"
Prepared by {enter your company name here} Page 19
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Stage -Discharge for Pond 3P: (BMP-4)
Elevation Discharge Primary Secondary
(feet)
(cfs)
(cfs)
(cfs)
631.00
0.00
0.00
0.00
631.10
0.01
0.01
0.00
631.20
0.02
0.02
0.00
631.30
0.04
0.04
0.00
631.40
0.05
0.05
0.00
631.50
0.06
0.06
0.00
631.60
0.07
0.07
0.00
631.70
0.08
0.08
0.00
631.80
0.10
0.10
0.00
631.90
0.11
0.11
0.00
632.00
0.12
0.12
0.00
632.10
0.12
0.12
0.00
632.20
0.13
0.13
0.00
632.30
0.13
0.13
0.00
632.40
0.14
0.14
0.00
632.50
0.14
0.14
0.00
632.60
0.15
0.15
0.00
632.70
0.15
0.15
0.00
632.80
0.16
0.16
0.00
632.90
0.16
0.16
0.00
633.00
0.17
0.17
0.00
633.10
0.20
0.20
0.00
633.20
0.29
0.29
0.00
633.30
0.41
0.41
0.00
633.40
0.55
0.55
0.00
633.50
0.66
0.66
0.00
633.60
0.76
0.76
0.00
633.70
0.84
0.84
0.00
633.80
0.91
0.91
0.00
633.90
0.97
0.97
0.00
634.00
1.03
1.03
0.00
634.10
1.09
1.09
0.00
634.20
1.15
1.15
0.00
634.30
1.20
1.20
0.00
634.40
1.25
1.25
0.00
634.50
1.30
1.30
0.00
634.60
1.34
1.34
0.00
634.70
1.39
1.39
0.00
634.80
1.43
1.43
0.00
634.90
1.47
1.47
0.00
635.00
1.51
1.51
0.00
635.10
1.55
1.55
0.00
635.20
1.59
1.59
0.00
635.30
1.63
1.63
0.00
635.40
1.67
1.67
0.00
635.50
1.71
1.71
0.00
635.60
1.74
1.74
0.00
635.70
1.78
1.78
0.00
635.80
1.81
1.81
0.00
635.90
1.85
1.85
0.00
636.00
1.88
1.88
0.00
636.10
2.95
2.95
0.00
Elevation Discharge Primary Secondary
(feet)
(cfs)
(cfs)
(cfs)
636.20
4.87
4.87
0.00
636.30
7.35
7.35
0.00
636.40
10.28
10.28
0.00
636.50
13.60
13.60
0.00
636.60
17.27
17.27
0.00
636.70
21.25
21.25
0.00
636.80
23.69
23.69
0.00
636.90
23.84
23.84
0.00
637.00
23.99
23.99
0.00
637.10
24.99
24.14
0.85
637.20
26.69
24.29
2.40
637.30
28.86
24.44
4.42
637.40
31.42
24.59
6.83
637.50
34.28
24.73
9.55
637.60
37.43
24.88
12.55
637.70
40.66
25.03
15.64
637.80
44.06
25.17
18.89
637.90
47.81
25.31
22.50
638.00
51.76
25.46
26.30

2020.17-BM P4
Type // 24-hr 10-yr Concord Rainfall=5.10"
Prepared by {enter your company name here} Page 20
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Stage -Area -Storage for Pond 3P: (BMP-4)
Elevation
Surface
Storage
(feet)
(sq-ft)
(cubic -feet)
631.00
10,175
0
631.10
10,312
1,024
631.20
10,449
2,062
631.30
10,586
3,114
631.40
10,723
4,180
631.50
10,860
5,259
631.60
10,996
6,351
631.70
11,133
7,458
631.80
11,270
8,578
631.90
11,407
9,712
632.00
11,544
10,860
632.10
11,690
12,021
632.20
11,836
13,197
632.30
11,982
14,388
632.40
12,127
15,594
632.50
12,273
16,814
632.60
12,419
18,048
632.70
12,565
19,298
632.80
12,711
20,561
632.90
12,857
21,840
633.00
13,003
23,133
633.10
13,148
24,440
633.20
13,294
25,762
633.30
13,440
27,099
633.40
13,586
28,450
633.50
13,732
29,816
633.60
13,878
31,197
633.70
14,023
32,592
633.80
14,169
34,001
633.90
14,315
35,426
634.00
14,461
36,865
634.10
14,618
38,318
634.20
14,775
39,788
634.30
14,932
41,274
634.40
15,090
42,775
634.50
15,247
44,291
634.60
15,404
45,824
634.70
15,561
47,372
634.80
15,718
48,936
634.90
15,875
50,516
635.00
16,033
52,111
635.10
16,190
53,722
635.20
16,347
55,349
635.30
16,504
56,992
635.40
16,661
58,650
635.50
16,818
60,324
635.60
16,975
62,014
635.70
17,133
63,719
635.80
17,290
65,440
635.90
17,447
67,177
636.00
17,604
68,930
636.10
17,811
70,700
Elevation
Surface
Storage
(feet)
(sq-ft)
(cubic -feet)
636.20
18,017
72,492
636.30
18,224
74,304
636.40
18,431
76,136
636.50
18,637
77,990
636.60
18,844
79,864
636.70
19,051
81,759
636.80
19,257
83,674
636.90
19,464
85,610
637.00
19,671
87,567
637.10
19,877
89,544
637.20
20,084
91,542
637.30
20,290
93,561
637.40
20,497
95,600
637.50
20,704
97,660
637.60
20,910
99,741
637.70
21,117
101,842
637.80
21,324
103,964
637.90
21,530
106,107
638.00
21,737
108,271

2020.17-BM P4 Type/1 24-hr 25-yr Concord Rainfall=6.00"
Prepared by {enter your company name here} Page 21
HvdroCAD® 8.00 s/n 004317 © 2006 HvdroCAD Software Solutions LLC 6/5/2022
Time span=0.00-200.00 hrs, dt=0.01 hrs, 20001 points
Runoff by SCS TR-20 method, UH=SCS
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment 1S: (Predeveloped) Runoff Area=9.560 ac Runoff Depth=3.38"
Flow Length=512' Tc=14.6 min CN=76 Runoff=42.38 cfs 2.693 of
Subcatchment 2S: (Post Developed) Runoff Area=9.560 ac Runoff Depth=4.09"
Tc=5.0 min CN=83 Runoff=69.72 cfs 3.259 of
Pond 3P: (BMP-4) Peak Elev=636.38' Storage=75,726 cf Inflow=69.72 cfs 3.259 of
Primary=9.61 cfs 3.259 of Secondary=0.00 cfs 0.000 of Outflow=9.61 cfs 3.259 of
Total Runoff Area = 19.120 ac Runoff Volume = 5.952 of Average Runoff Depth = 3.74"
100.00% Pervious Area = 19.120 ac 0.00% Impervious Area = 0.000 ac

2020.17-BM P4 Type/1 24-hr 25-yr Concord Rainfall=6.00"
Prepared by {enter your company name here} Page 22
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Subcatchment 1S: (Predeveloped)
BASED ON EXISTING CONDITIONS
Runoff = 42.38 cfs @ 12.07 hrs, Volume= 2.693 af, Depth= 3.38"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Type II 24-hr 25-yr Concord Rainfall=6.00"
Area (ac) CN Description
4.920 73 Woods, Fair, HSG C
4.640 79 Pasture/grassland/range, Fair, HSG C
9.560 76 Weighted Average
9.560 Pervious Area
Tc
Length
Slope
Velocity
Capacity Description
(min)
(feet)
(ft/ft)
(ft/sec)
(cfs)
10.0
100
0.0439
0.17
Sheet Flow,
Grass: Dense n= 0.240 P2= 3.50"
4.6
412
0.0875
1.48
Shallow Concentrated Flow,
Woodland Kv= 5.0 fps
14.6 512 Total

2020.17-BM P4
Type // 24-hr 25-yr Concord Rainfall=6.00"
Prepared by {enter your company name here} Page 23
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Hydrograph for Subcatchment 1S: (Predeveloped)
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
0.00
0.00
0.00
0.00
2.00
0.13
0.00
0.00
4.00
0.29
0.00
0.00
6.00
0.48
0.00
0.00
8.00
0.72
0.00
0.05
10.00
1.09
0.06
0.45
12.00
3.98
1.72
35.97
14.00
4.92
2.47
1.96
16.00
5.28
2.77
1.19
18.00
5.53
2.97
0.91
20.00
5.71
3.13
0.67
22.00
5.86
3.26
0.60
24.00
6.00
3.38
0.55
26.00
6.00
3.38
0.00
28.00
6.00
3.38
0.00
30.00
6.00
3.38
0.00
32.00
6.00
3.38
0.00
34.00
6.00
3.38
0.00
36.00
6.00
3.38
0.00
38.00
6.00
3.38
0.00
40.00
6.00
3.38
0.00
42.00
6.00
3.38
0.00
44.00
6.00
3.38
0.00
46.00
6.00
3.38
0.00
48.00
6.00
3.38
0.00
50.00
6.00
3.38
0.00
52.00
6.00
3.38
0.00
54.00
6.00
3.38
0.00
56.00
6.00
3.38
0.00
58.00
6.00
3.38
0.00
60.00
6.00
3.38
0.00
62.00
6.00
3.38
0.00
64.00
6.00
3.38
0.00
66.00
6.00
3.38
0.00
68.00
6.00
3.38
0.00
70.00
6.00
3.38
0.00
72.00
6.00
3.38
0.00
74.00
6.00
3.38
0.00
76.00
6.00
3.38
0.00
78.00
6.00
3.38
0.00
80.00
6.00
3.38
0.00
82.00
6.00
3.38
0.00
84.00
6.00
3.38
0.00
86.00
6.00
3.38
0.00
88.00
6.00
3.38
0.00
90.00
6.00
3.38
0.00
92.00
6.00
3.38
0.00
94.00
6.00
3.38
0.00
96.00
6.00
3.38
0.00
98.00
6.00
3.38
0.00
100.00
6.00
3.38
0.00
102.00
6.00
3.38
0.00
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
104.00
6.00
3.38
0.00
106.00
6.00
3.38
0.00
108.00
6.00
3.38
0.00
110.00
6.00
3.38
0.00
112.00
6.00
3.38
0.00
114.00
6.00
3.38
0.00
116.00
6.00
3.38
0.00
118.00
6.00
3.38
0.00
120.00
6.00
3.38
0.00
122.00
6.00
3.38
0.00
124.00
6.00
3.38
0.00
126.00
6.00
3.38
0.00
128.00
6.00
3.38
0.00
130.00
6.00
3.38
0.00
132.00
6.00
3.38
0.00
134.00
6.00
3.38
0.00
136.00
6.00
3.38
0.00
138.00
6.00
3.38
0.00
140.00
6.00
3.38
0.00
142.00
6.00
3.38
0.00
144.00
6.00
3.38
0.00
146.00
6.00
3.38
0.00
148.00
6.00
3.38
0.00
150.00
6.00
3.38
0.00
152.00
6.00
3.38
0.00
154.00
6.00
3.38
0.00
156.00
6.00
3.38
0.00
158.00
6.00
3.38
0.00
160.00
6.00
3.38
0.00
162.00
6.00
3.38
0.00
164.00
6.00
3.38
0.00
166.00
6.00
3.38
0.00
168.00
6.00
3.38
0.00
170.00
6.00
3.38
0.00
172.00
6.00
3.38
0.00
174.00
6.00
3.38
0.00
176.00
6.00
3.38
0.00
178.00
6.00
3.38
0.00
180.00
6.00
3.38
0.00
182.00
6.00
3.38
0.00
184.00
6.00
3.38
0.00
186.00
6.00
3.38
0.00
188.00
6.00
3.38
0.00
190.00
6.00
3.38
0.00
192.00
6.00
3.38
0.00
194.00
6.00
3.38
0.00
196.00
6.00
3.38
0.00
198.00
6.00
3.38
0.00
200.00
6.00
3.38
0.00

2020.17-BM P4
Type/1 24-hr 25-yr Concord Rainfall=6.00"
Prepared by {enter your company name here} Page 24
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Subcatchment 2S: (Post Developed)
Runoff = 69.72 cfs @ 11.96 hrs, Volume= 3.259 af, Depth= 4.09"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Type II 24-hr 25-yr Concord Rainfall=6.00"
Area (ac) CN Description
9.560 83 RM-2 (C)
9.560 Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,

2020.17-BM P4
Type // 24-hr 25-yr Concord Rainfall=6.00"
Prepared by {enter your company name here} Page 25
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Hydrograph for Subcatchment 2S: (Post Developed)
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
0.00
0.00
0.00
0.00
2.00
0.13
0.00
0.00
4.00
0.29
0.00
0.00
6.00
0.48
0.00
0.06
8.00
0.72
0.04
0.30
10.00
1.09
0.17
0.96
12.00
3.98
2.27
58.79
14.00
4.92
3.10
2.01
16.00
5.28
3.43
1.24
18.00
5.53
3.65
0.97
20.00
5.71
3.82
0.70
22.00
5.86
3.96
0.64
24.00
6.00
4.09
0.59
26.00
6.00
4.09
0.00
28.00
6.00
4.09
0.00
30.00
6.00
4.09
0.00
32.00
6.00
4.09
0.00
34.00
6.00
4.09
0.00
36.00
6.00
4.09
0.00
38.00
6.00
4.09
0.00
40.00
6.00
4.09
0.00
42.00
6.00
4.09
0.00
44.00
6.00
4.09
0.00
46.00
6.00
4.09
0.00
48.00
6.00
4.09
0.00
50.00
6.00
4.09
0.00
52.00
6.00
4.09
0.00
54.00
6.00
4.09
0.00
56.00
6.00
4.09
0.00
58.00
6.00
4.09
0.00
60.00
6.00
4.09
0.00
62.00
6.00
4.09
0.00
64.00
6.00
4.09
0.00
66.00
6.00
4.09
0.00
68.00
6.00
4.09
0.00
70.00
6.00
4.09
0.00
72.00
6.00
4.09
0.00
74.00
6.00
4.09
0.00
76.00
6.00
4.09
0.00
78.00
6.00
4.09
0.00
80.00
6.00
4.09
0.00
82.00
6.00
4.09
0.00
84.00
6.00
4.09
0.00
86.00
6.00
4.09
0.00
88.00
6.00
4.09
0.00
90.00
6.00
4.09
0.00
92.00
6.00
4.09
0.00
94.00
6.00
4.09
0.00
96.00
6.00
4.09
0.00
98.00
6.00
4.09
0.00
100.00
6.00
4.09
0.00
102.00
6.00
4.09
0.00
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
104.00
6.00
4.09
0.00
106.00
6.00
4.09
0.00
108.00
6.00
4.09
0.00
110.00
6.00
4.09
0.00
112.00
6.00
4.09
0.00
114.00
6.00
4.09
0.00
116.00
6.00
4.09
0.00
118.00
6.00
4.09
0.00
120.00
6.00
4.09
0.00
122.00
6.00
4.09
0.00
124.00
6.00
4.09
0.00
126.00
6.00
4.09
0.00
128.00
6.00
4.09
0.00
130.00
6.00
4.09
0.00
132.00
6.00
4.09
0.00
134.00
6.00
4.09
0.00
136.00
6.00
4.09
0.00
138.00
6.00
4.09
0.00
140.00
6.00
4.09
0.00
142.00
6.00
4.09
0.00
144.00
6.00
4.09
0.00
146.00
6.00
4.09
0.00
148.00
6.00
4.09
0.00
150.00
6.00
4.09
0.00
152.00
6.00
4.09
0.00
154.00
6.00
4.09
0.00
156.00
6.00
4.09
0.00
158.00
6.00
4.09
0.00
160.00
6.00
4.09
0.00
162.00
6.00
4.09
0.00
164.00
6.00
4.09
0.00
166.00
6.00
4.09
0.00
168.00
6.00
4.09
0.00
170.00
6.00
4.09
0.00
172.00
6.00
4.09
0.00
174.00
6.00
4.09
0.00
176.00
6.00
4.09
0.00
178.00
6.00
4.09
0.00
180.00
6.00
4.09
0.00
182.00
6.00
4.09
0.00
184.00
6.00
4.09
0.00
186.00
6.00
4.09
0.00
188.00
6.00
4.09
0.00
190.00
6.00
4.09
0.00
192.00
6.00
4.09
0.00
194.00
6.00
4.09
0.00
196.00
6.00
4.09
0.00
198.00
6.00
4.09
0.00
200.00
6.00
4.09
0.00

2020.17-BM P4
Type/1 24-hr 25-yr Concord Rainfall=6.00"
Prepared by {enter your company name here} Page 26
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Pond 3P: (BMP-4)
Inflow Area = 9.560 ac, Inflow Depth = 4.09" for 25-yr Concord event
Inflow =
69.72 cfs @
11.96 hrs,
Volume=
3.259 of
Outflow =
9.61 cfs @
12.17 hrs,
Volume=
3.259 af, Atten= 86%, Lag= 12.7 min
Primary =
9.61 cfs @
12.17 hrs,
Volume=
3.259 of
Secondary =
0.00 cfs @
0.00 hrs,
Volume=
0.000 of
Routing by Stor-Ind method, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Peak Elev= 636.38' @ 12.17 hrs Surf.Area= 18,385 sf Storage= 75,726 cf
Plug -Flow detention time= 728.9 min calculated for 3.259 of (100% of inflow)
Center -of -Mass det. time= 729.3 min ( 1,531.5 - 802.2 )
Volume Invert
Avail.Storage Storage Description
#1 631.00'
108,271 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area
Inc.Store Cum.Store
(feet)
(sq-ft)
(cubic -feet) (cubic -feet)
631.00
10,175
0 0
632.00
11,544
10,860 10,860
634.00
14,461
26,005 36,865
636.00
17,604
32,065 68,930
638.00
21,737
39,341 108,271
Device Routing
Invert
Outlet Devices
#1 Primary
628.30'
18.0" x 58.5' long Culvert RCP, square edge headwall, Ke= 0.500
Outlet Invert= 628.00' S= 0.0051 T Cc= 0.900 n= 0.013
#2 Device 1
631.00'
Exfiltration
Head (feet) 0.00 1.00 2.00 3.00 4.00 5.00 6.00
Disch. (cfs) 0.000 0.120 0.168 0.216 0.264 0.312 0.360
#3 Device 1
633.00'
6.0" Vert. Orifice/Grate C= 0.600
#4 Device 1
636.00'
2.00' x 3.00' Horiz. Top of Riser Limited to weir flow C= 0.600
#5 Secondary
637.00'
10.0' long x 16.0' breadth Spillway
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Coef. (English) 2.68 2.70 2.70 2.64 2.63 2.64 2.64 2.63
Primary OutFlow Max=9.59 cfs @ 12.17 hrs HW=636.38' (Free Discharge)
L1=Culvert (Passes 9.59 cfs of 23.03 cfs potential flow)
2=Exfltration (Custom Controls 0.33 cfs)
3=Orifice/Grate (Orifice Controls 1.67 cfs @ 8.52 fps)
=Top of Riser (Weir Controls 7.59 cfs @ 2.01 fps)
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=631.00' (Free Discharge)
5=Spillway ( Controls 0.00 cfs)

2020.17-BM P4
Type // 24-hr 25-yr Concord Rainfall=6.00"
Prepared by {enter your company name here} Page 27
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Hydrograph for Pond 3P: (BMP-4)
Time
Inflow
Storage
Elevation
Outflow
Primary
Secondary
(hours)
(cfs)
(cubic -feet)
(feet)
(cfs)
(cfs)
(cfs)
0.00
0.00
0
631.00
0.00
0.00
0.00
5.00
0.00
0
631.00
0.00
0.00
0.00
10.00
0.96
5,265
631.50
0.06
0.06
0.00
15.00
1.60
68,905
636.00
1.88
1.88
0.00
20.00
0.70
56,138
635.25
1.61
1.61
0.00
25.00
0.00
40,155
634.22
1.16
1.16
0.00
30.00
0.00
26,464
633.25
0.35
0.35
0.00
35.00
0.00
22,609
632.96
0.17
0.17
0.00
40.00
0.00
19,718
632.73
0.16
0.16
0.00
45.00
0.00
17,019
632.52
0.14
0.14
0.00
50.00
0.00
14,503
632.31
0.13
0.13
0.00
55.00
0.00
12,161
632.11
0.13
0.13
0.00
60.00
0.00
10,006
631.93
0.11
0.11
0.00
65.00
0.00
8,185
631.77
0.09
0.09
0.00
70.00
0.00
6,683
631.63
0.08
0.08
0.00
75.00
0.00
5,447
631.52
0.06
0.06
0.00
80.00
0.00
4,434
631.42
0.05
0.05
0.00
85.00
0.00
3,606
631.35
0.04
0.04
0.00
90.00
0.00
2,929
631.28
0.03
0.03
0.00
95.00
0.00
2,377
631.23
0.03
0.03
0.00
100.00
0.00
1,928
631.19
0.02
0.02
0.00
105.00
0.00
1,563
631.15
0.02
0.02
0.00
110.00
0.00
1,267
631.12
0.01
0.01
0.00
115.00
0.00
1,026
631.10
0.01
0.01
0.00
120.00
0.00
831
631.08
0.01
0.01
0.00
125.00
0.00
673
631.07
0.01
0.01
0.00
130.00
0.00
545
631.05
0.01
0.01
0.00
135.00
0.00
441
631.04
0.01
0.01
0.00
140.00
0.00
357
631.03
0.00
0.00
0.00
145.00
0.00
289
631.03
0.00
0.00
0.00
150.00
0.00
234
631.02
0.00
0.00
0.00
155.00
0.00
189
631.02
0.00
0.00
0.00
160.00
0.00
153
631.01
0.00
0.00
0.00
165.00
0.00
124
631.01
0.00
0.00
0.00
170.00
0.00
100
631.01
0.00
0.00
0.00
175.00
0.00
81
631.01
0.00
0.00
0.00
180.00
0.00
66
631.01
0.00
0.00
0.00
185.00
0.00
53
631.01
0.00
0.00
0.00
190.00
0.00
43
631.00
0.00
0.00
0.00
195.00
0.00
35
631.00
0.00
0.00
0.00
200.00
0.00
28
631.00
0.00
0.00
0.00

2020.17-BM P4
Type // 24-hr 25-yr Concord Rainfall=6.00"
Prepared by {enter your company name here} Page 28
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Stage -Discharge for Pond 3P: (BMP-4)
Elevation Discharge Primary Secondary
(feet)
(cfs)
(cfs)
(cfs)
631.00
0.00
0.00
0.00
631.10
0.01
0.01
0.00
631.20
0.02
0.02
0.00
631.30
0.04
0.04
0.00
631.40
0.05
0.05
0.00
631.50
0.06
0.06
0.00
631.60
0.07
0.07
0.00
631.70
0.08
0.08
0.00
631.80
0.10
0.10
0.00
631.90
0.11
0.11
0.00
632.00
0.12
0.12
0.00
632.10
0.12
0.12
0.00
632.20
0.13
0.13
0.00
632.30
0.13
0.13
0.00
632.40
0.14
0.14
0.00
632.50
0.14
0.14
0.00
632.60
0.15
0.15
0.00
632.70
0.15
0.15
0.00
632.80
0.16
0.16
0.00
632.90
0.16
0.16
0.00
633.00
0.17
0.17
0.00
633.10
0.20
0.20
0.00
633.20
0.29
0.29
0.00
633.30
0.41
0.41
0.00
633.40
0.55
0.55
0.00
633.50
0.66
0.66
0.00
633.60
0.76
0.76
0.00
633.70
0.84
0.84
0.00
633.80
0.91
0.91
0.00
633.90
0.97
0.97
0.00
634.00
1.03
1.03
0.00
634.10
1.09
1.09
0.00
634.20
1.15
1.15
0.00
634.30
1.20
1.20
0.00
634.40
1.25
1.25
0.00
634.50
1.30
1.30
0.00
634.60
1.34
1.34
0.00
634.70
1.39
1.39
0.00
634.80
1.43
1.43
0.00
634.90
1.47
1.47
0.00
635.00
1.51
1.51
0.00
635.10
1.55
1.55
0.00
635.20
1.59
1.59
0.00
635.30
1.63
1.63
0.00
635.40
1.67
1.67
0.00
635.50
1.71
1.71
0.00
635.60
1.74
1.74
0.00
635.70
1.78
1.78
0.00
635.80
1.81
1.81
0.00
635.90
1.85
1.85
0.00
636.00
1.88
1.88
0.00
636.10
2.95
2.95
0.00
Elevation Discharge Primary Secondary
(feet)
(cfs)
(cfs)
(cfs)
636.20
4.87
4.87
0.00
636.30
7.35
7.35
0.00
636.40
10.28
10.28
0.00
636.50
13.60
13.60
0.00
636.60
17.27
17.27
0.00
636.70
21.25
21.25
0.00
636.80
23.69
23.69
0.00
636.90
23.84
23.84
0.00
637.00
23.99
23.99
0.00
637.10
24.99
24.14
0.85
637.20
26.69
24.29
2.40
637.30
28.86
24.44
4.42
637.40
31.42
24.59
6.83
637.50
34.28
24.73
9.55
637.60
37.43
24.88
12.55
637.70
40.66
25.03
15.64
637.80
44.06
25.17
18.89
637.90
47.81
25.31
22.50
638.00
51.76
25.46
26.30

2020.17-BM P4
Type // 24-hr 25-yr Concord Rainfall=6.00"
Prepared by {enter your company name here} Page 29
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Stage -Area -Storage for Pond 3P: (BMP-4)
Elevation
Surface
Storage
(feet)
(sq-ft)
(cubic -feet)
631.00
10,175
0
631.10
10,312
1,024
631.20
10,449
2,062
631.30
10,586
3,114
631.40
10,723
4,180
631.50
10,860
5,259
631.60
10,996
6,351
631.70
11,133
7,458
631.80
11,270
8,578
631.90
11,407
9,712
632.00
11,544
10,860
632.10
11,690
12,021
632.20
11,836
13,197
632.30
11,982
14,388
632.40
12,127
15,594
632.50
12,273
16,814
632.60
12,419
18,048
632.70
12,565
19,298
632.80
12,711
20,561
632.90
12,857
21,840
633.00
13,003
23,133
633.10
13,148
24,440
633.20
13,294
25,762
633.30
13,440
27,099
633.40
13,586
28,450
633.50
13,732
29,816
633.60
13,878
31,197
633.70
14,023
32,592
633.80
14,169
34,001
633.90
14,315
35,426
634.00
14,461
36,865
634.10
14,618
38,318
634.20
14,775
39,788
634.30
14,932
41,274
634.40
15,090
42,775
634.50
15,247
44,291
634.60
15,404
45,824
634.70
15,561
47,372
634.80
15,718
48,936
634.90
15,875
50,516
635.00
16,033
52,111
635.10
16,190
53,722
635.20
16,347
55,349
635.30
16,504
56,992
635.40
16,661
58,650
635.50
16,818
60,324
635.60
16,975
62,014
635.70
17,133
63,719
635.80
17,290
65,440
635.90
17,447
67,177
636.00
17,604
68,930
636.10
17,811
70,700
Elevation
Surface
Storage
(feet)
(sq-ft)
(cubic -feet)
636.20
18,017
72,492
636.30
18,224
74,304
636.40
18,431
76,136
636.50
18,637
77,990
636.60
18,844
79,864
636.70
19,051
81,759
636.80
19,257
83,674
636.90
19,464
85,610
637.00
19,671
87,567
637.10
19,877
89,544
637.20
20,084
91,542
637.30
20,290
93,561
637.40
20,497
95,600
637.50
20,704
97,660
637.60
20,910
99,741
637.70
21,117
101,842
637.80
21,324
103,964
637.90
21,530
106,107
638.00
21,737
108,271

2020.17-BM P4 Type 11 24-hr 50-yr Concord Rainfall=6.80"
Prepared by {enter your company name here} Page 30
HvdroCAD® 8.00 s/n 004317 © 2006 HvdroCAD Software Solutions LLC 6/5/2022
Time span=0.00-200.00 hrs, dt=0.01 hrs, 20001 points
Runoff by SCS TR-20 method, UH=SCS
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment 1S: (Predeveloped) Runoff Area=9.560 ac Runoff Depth=4.08"
Flow Length=512' Tc=14.6 min CN=76 Runoff=51.00 cfs 3.250 of
Subcatchment 2S: (Post Developed) Runoff Area=9.560 ac Runoff Depth=4.84"
Tc=5.0 min CN=83 Runoff=81.64 cfs 3.855 of
Pond 3P: (BMP-4) Peak Elev=636.83' Storage=84,242 cf Inflow=81.64 cfs 3.855 of
Primary=23.73 cfs 3.855 of Secondary=0.00 cfs 0.000 of Outflow=23.73 cfs 3.855 of
Total Runoff Area = 19.120 ac Runoff Volume = 7.106 of Average Runoff Depth = 4.46"
100.00% Pervious Area = 19.120 ac 0.00% Impervious Area = 0.000 ac

2020.17-BM P4 Type 11 24-hr 50-yr Concord Rainfall=6.80"
Prepared by {enter your company name here} Page 31
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Subcatchment 1S: (Predeveloped)
BASED ON EXISTING CONDITIONS
Runoff = 51.00 cfs @ 12.06 hrs, Volume= 3.250 af, Depth= 4.08"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Type II 24-hr 50-yr Concord Rainfall=6.80"
Area (ac) CN Description
4.920 73 Woods, Fair, HSG C
4.640 79 Pasture/grassland/range, Fair, HSG C
9.560 76 Weighted Average
9.560 Pervious Area
Tc
Length
Slope
Velocity
Capacity Description
(min)
(feet)
(ft/ft)
(ft/sec)
(cfs)
10.0
100
0.0439
0.17
Sheet Flow,
Grass: Dense n= 0.240 P2= 3.50"
4.6
412
0.0875
1.48
Shallow Concentrated Flow,
Woodland Kv= 5.0 fps
14.6 512 Total

2020.17-BM P4
Type // 24-hr 50-yr Concord Rainfall=6.80"
Prepared by {enter your company name here} Page 32
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Hydrograph for Subcatchment 1S: (Predeveloped)
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
0.00
0.00
0.00
0.00
2.00
0.15
0.00
0.00
4.00
0.33
0.00
0.00
6.00
0.54
0.00
0.00
8.00
0.82
0.01
0.13
10.00
1.23
0.10
0.65
12.00
4.51
2.14
43.62
14.00
5.58
3.02
2.30
16.00
5.98
3.37
1.39
18.00
6.26
3.61
1.06
20.00
6.47
3.79
0.78
22.00
6.64
3.94
0.70
24.00
6.80
4.08
0.64
26.00
6.80
4.08
0.00
28.00
6.80
4.08
0.00
30.00
6.80
4.08
0.00
32.00
6.80
4.08
0.00
34.00
6.80
4.08
0.00
36.00
6.80
4.08
0.00
38.00
6.80
4.08
0.00
40.00
6.80
4.08
0.00
42.00
6.80
4.08
0.00
44.00
6.80
4.08
0.00
46.00
6.80
4.08
0.00
48.00
6.80
4.08
0.00
50.00
6.80
4.08
0.00
52.00
6.80
4.08
0.00
54.00
6.80
4.08
0.00
56.00
6.80
4.08
0.00
58.00
6.80
4.08
0.00
60.00
6.80
4.08
0.00
62.00
6.80
4.08
0.00
64.00
6.80
4.08
0.00
66.00
6.80
4.08
0.00
68.00
6.80
4.08
0.00
70.00
6.80
4.08
0.00
72.00
6.80
4.08
0.00
74.00
6.80
4.08
0.00
76.00
6.80
4.08
0.00
78.00
6.80
4.08
0.00
80.00
6.80
4.08
0.00
82.00
6.80
4.08
0.00
84.00
6.80
4.08
0.00
86.00
6.80
4.08
0.00
88.00
6.80
4.08
0.00
90.00
6.80
4.08
0.00
92.00
6.80
4.08
0.00
94.00
6.80
4.08
0.00
96.00
6.80
4.08
0.00
98.00
6.80
4.08
0.00
100.00
6.80
4.08
0.00
102.00
6.80
4.08
0.00
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
104.00
6.80
4.08
0.00
106.00
6.80
4.08
0.00
108.00
6.80
4.08
0.00
110.00
6.80
4.08
0.00
112.00
6.80
4.08
0.00
114.00
6.80
4.08
0.00
116.00
6.80
4.08
0.00
118.00
6.80
4.08
0.00
120.00
6.80
4.08
0.00
122.00
6.80
4.08
0.00
124.00
6.80
4.08
0.00
126.00
6.80
4.08
0.00
128.00
6.80
4.08
0.00
130.00
6.80
4.08
0.00
132.00
6.80
4.08
0.00
134.00
6.80
4.08
0.00
136.00
6.80
4.08
0.00
138.00
6.80
4.08
0.00
140.00
6.80
4.08
0.00
142.00
6.80
4.08
0.00
144.00
6.80
4.08
0.00
146.00
6.80
4.08
0.00
148.00
6.80
4.08
0.00
150.00
6.80
4.08
0.00
152.00
6.80
4.08
0.00
154.00
6.80
4.08
0.00
156.00
6.80
4.08
0.00
158.00
6.80
4.08
0.00
160.00
6.80
4.08
0.00
162.00
6.80
4.08
0.00
164.00
6.80
4.08
0.00
166.00
6.80
4.08
0.00
168.00
6.80
4.08
0.00
170.00
6.80
4.08
0.00
172.00
6.80
4.08
0.00
174.00
6.80
4.08
0.00
176.00
6.80
4.08
0.00
178.00
6.80
4.08
0.00
180.00
6.80
4.08
0.00
182.00
6.80
4.08
0.00
184.00
6.80
4.08
0.00
186.00
6.80
4.08
0.00
188.00
6.80
4.08
0.00
190.00
6.80
4.08
0.00
192.00
6.80
4.08
0.00
194.00
6.80
4.08
0.00
196.00
6.80
4.08
0.00
198.00
6.80
4.08
0.00
200.00
6.80
4.08
0.00

2020.17-BM P4
Type 11 24-hr 50-yr Concord Rainfall=6.80"
Prepared by {enter your company name here} Page 33
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Subcatchment 2S: (Post Developed)
Runoff = 81.64 cfs @ 11.96 hrs, Volume= 3.855 af, Depth= 4.84"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Type II 24-hr 50-yr Concord Rainfall=6.80"
Area (ac) CN Description
9.560 83 RM-2 (C)
9.560 Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,

2020.17-BM P4
Type // 24-hr 50-yr Concord Rainfall=6.80"
Prepared by {enter your company name here} Page 34
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Hydrograph for Subcatchment 2S: (Post Developed)
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
0.00
0.00
0.00
0.00
2.00
0.15
0.00
0.00
4.00
0.33
0.00
0.00
6.00
0.54
0.01
0.13
8.00
0.82
0.07
0.43
10.00
1.23
0.24
1.23
12.00
4.51
2.73
68.63
14.00
5.58
3.70
2.32
16.00
5.98
4.08
1.43
18.00
6.26
4.34
1.11
20.00
6.47
4.53
0.81
22.00
6.64
4.69
0.74
24.00
6.80
4.84
0.68
26.00
6.80
4.84
0.00
28.00
6.80
4.84
0.00
30.00
6.80
4.84
0.00
32.00
6.80
4.84
0.00
34.00
6.80
4.84
0.00
36.00
6.80
4.84
0.00
38.00
6.80
4.84
0.00
40.00
6.80
4.84
0.00
42.00
6.80
4.84
0.00
44.00
6.80
4.84
0.00
46.00
6.80
4.84
0.00
48.00
6.80
4.84
0.00
50.00
6.80
4.84
0.00
52.00
6.80
4.84
0.00
54.00
6.80
4.84
0.00
56.00
6.80
4.84
0.00
58.00
6.80
4.84
0.00
60.00
6.80
4.84
0.00
62.00
6.80
4.84
0.00
64.00
6.80
4.84
0.00
66.00
6.80
4.84
0.00
68.00
6.80
4.84
0.00
70.00
6.80
4.84
0.00
72.00
6.80
4.84
0.00
74.00
6.80
4.84
0.00
76.00
6.80
4.84
0.00
78.00
6.80
4.84
0.00
80.00
6.80
4.84
0.00
82.00
6.80
4.84
0.00
84.00
6.80
4.84
0.00
86.00
6.80
4.84
0.00
88.00
6.80
4.84
0.00
90.00
6.80
4.84
0.00
92.00
6.80
4.84
0.00
94.00
6.80
4.84
0.00
96.00
6.80
4.84
0.00
98.00
6.80
4.84
0.00
100.00
6.80
4.84
0.00
102.00
6.80
4.84
0.00
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
104.00
6.80
4.84
0.00
106.00
6.80
4.84
0.00
108.00
6.80
4.84
0.00
110.00
6.80
4.84
0.00
112.00
6.80
4.84
0.00
114.00
6.80
4.84
0.00
116.00
6.80
4.84
0.00
118.00
6.80
4.84
0.00
120.00
6.80
4.84
0.00
122.00
6.80
4.84
0.00
124.00
6.80
4.84
0.00
126.00
6.80
4.84
0.00
128.00
6.80
4.84
0.00
130.00
6.80
4.84
0.00
132.00
6.80
4.84
0.00
134.00
6.80
4.84
0.00
136.00
6.80
4.84
0.00
138.00
6.80
4.84
0.00
140.00
6.80
4.84
0.00
142.00
6.80
4.84
0.00
144.00
6.80
4.84
0.00
146.00
6.80
4.84
0.00
148.00
6.80
4.84
0.00
150.00
6.80
4.84
0.00
152.00
6.80
4.84
0.00
154.00
6.80
4.84
0.00
156.00
6.80
4.84
0.00
158.00
6.80
4.84
0.00
160.00
6.80
4.84
0.00
162.00
6.80
4.84
0.00
164.00
6.80
4.84
0.00
166.00
6.80
4.84
0.00
168.00
6.80
4.84
0.00
170.00
6.80
4.84
0.00
172.00
6.80
4.84
0.00
174.00
6.80
4.84
0.00
176.00
6.80
4.84
0.00
178.00
6.80
4.84
0.00
180.00
6.80
4.84
0.00
182.00
6.80
4.84
0.00
184.00
6.80
4.84
0.00
186.00
6.80
4.84
0.00
188.00
6.80
4.84
0.00
190.00
6.80
4.84
0.00
192.00
6.80
4.84
0.00
194.00
6.80
4.84
0.00
196.00
6.80
4.84
0.00
198.00
6.80
4.84
0.00
200.00
6.80
4.84
0.00

2020.17-BM P4
Type 11 24-hr 50-yr Concord Rainfall=6.80"
Prepared by {enter your company name here} Page 35
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Pond 3P: (BMP-4)
Inflow Area = 9.560 ac, Inflow Depth = 4.84" for 50-yr Concord event
Inflow =
81.64 cfs @
11.96 hrs,
Volume=
3.855 of
Outflow =
23.73 cfs @
12.08 hrs,
Volume=
3.855 af, Atten= 71 %, Lag= 7.0 min
Primary =
23.73 cfs @
12.08 hrs,
Volume=
3.855 of
Secondary =
0.00 cfs @
0.00 hrs,
Volume=
0.000 of
Routing by Stor-Ind method, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Peak Elev= 636.83' @ 12.08 hrs Surf.Area= 19,318 sf Storage= 84,242 cf
Plug -Flow detention time= 639.3 min calculated for 3.855 of (100% of inflow)
Center -of -Mass det. time= 639.2 min ( 1,436.7 - 797.5 )
Volume Invert
Avail.Storage Storage Description
#1 631.00'
108,271 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area
Inc.Store Cum.Store
(feet)
(sq-ft)
(cubic -feet) (cubic -feet)
631.00
10,175
0 0
632.00
11,544
10,860 10,860
634.00
14,461
26,005 36,865
636.00
17,604
32,065 68,930
638.00
21,737
39,341 108,271
Device Routing
Invert
Outlet Devices
#1 Primary
628.30'
18.0" x 58.5' long Culvert RCP, square edge headwall, Ke= 0.500
Outlet Invert= 628.00' S= 0.0051 T Cc= 0.900 n= 0.013
#2 Device 1
631.00'
Exfiltration
Head (feet) 0.00 1.00 2.00 3.00 4.00 5.00 6.00
Disch. (cfs) 0.000 0.120 0.168 0.216 0.264 0.312 0.360
#3 Device 1
633.00'
6.0" Vert. Orifice/Grate C= 0.600
#4 Device 1
636.00'
2.00' x 3.00' Horiz. Top of Riser Limited to weir flow C= 0.600
#5 Secondary
637.00'
10.0' long x 16.0' breadth Spillway
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Coef. (English) 2.68 2.70 2.70 2.64 2.63 2.64 2.64 2.63
Primary OutFlow Max=23.73 cfs @ 12.08 hrs HW=636.83' (Free Discharge)
L1=Culvert (Inlet Controls 23.73 cfs @ 13.43 fps)
2=Exfltration (Passes < 0.35 cfs potential flow)
3=Orifice/Grate (Passes < 1.79 cfs potential flow)
=Top of Riser (Passes < 24.67 cfs potential flow)
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=631.00' (Free Discharge)
5=Spillway ( Controls 0.00 cfs)

2020.17-BM P4
Type // 24-hr 50-yr Concord Rainfall=6.80"
Prepared by {enter your company name here} Page 36
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Hydrograph for Pond 3P: (BMP-4)
Time
Inflow
Storage
Elevation
Outflow
Primary
Secondary
(hours)
(cfs)
(cubic -feet)
(feet)
(cfs)
(cfs)
(cfs)
0.00
0.00
0
631.00
0.00
0.00
0.00
5.00
0.01
2
631.00
0.00
0.00
0.00
10.00
1.23
7,361
631.69
0.08
0.08
0.00
15.00
1.85
69,433
636.03
2.08
2.08
0.00
20.00
0.81
58,717
635.40
1.67
1.67
0.00
25.00
0.00
42,786
634.40
1.25
1.25
0.00
30.00
0.00
27,318
633.32
0.43
0.43
0.00
35.00
0.00
22,973
632.99
0.17
0.17
0.00
40.00
0.00
20,059
632.76
0.16
0.16
0.00
45.00
0.00
17,336
632.54
0.15
0.15
0.00
50.00
0.00
14,798
632.33
0.14
0.14
0.00
55.00
0.00
12,436
632.14
0.13
0.13
0.00
60.00
0.00
10,252
631.95
0.11
0.11
0.00
65.00
0.00
8,388
631.78
0.09
0.09
0.00
70.00
0.00
6,850
631.65
0.08
0.08
0.00
75.00
0.00
5,585
631.53
0.06
0.06
0.00
80.00
0.00
4,547
631.43
0.05
0.05
0.00
85.00
0.00
3,697
631.35
0.04
0.04
0.00
90.00
0.00
3,004
631.29
0.03
0.03
0.00
95.00
0.00
2,438
631.24
0.03
0.03
0.00
100.00
0.00
1,978
631.19
0.02
0.02
0.00
105.00
0.00
1,604
631.16
0.02
0.02
0.00
110.00
0.00
1,300
631.13
0.02
0.02
0.00
115.00
0.00
1,053
631.10
0.01
0.01
0.00
120.00
0.00
853
631.08
0.01
0.01
0.00
125.00
0.00
690
631.07
0.01
0.01
0.00
130.00
0.00
559
631.05
0.01
0.01
0.00
135.00
0.00
452
631.04
0.01
0.01
0.00
140.00
0.00
366
631.04
0.00
0.00
0.00
145.00
0.00
297
631.03
0.00
0.00
0.00
150.00
0.00
240
631.02
0.00
0.00
0.00
155.00
0.00
194
631.02
0.00
0.00
0.00
160.00
0.00
157
631.02
0.00
0.00
0.00
165.00
0.00
127
631.01
0.00
0.00
0.00
170.00
0.00
103
631.01
0.00
0.00
0.00
175.00
0.00
83
631.01
0.00
0.00
0.00
180.00
0.00
68
631.01
0.00
0.00
0.00
185.00
0.00
55
631.01
0.00
0.00
0.00
190.00
0.00
44
631.00
0.00
0.00
0.00
195.00
0.00
36
631.00
0.00
0.00
0.00
200.00
0.00
29
631.00
0.00
0.00
0.00

2020.17-BM P4
Type // 24-hr 50-yr Concord Rainfall=6.80"
Prepared by {enter your company name here} Page 37
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Stage -Discharge for Pond 3P: (BMP-4)
Elevation Discharge Primary Secondary
(feet)
(cfs)
(cfs)
(cfs)
631.00
0.00
0.00
0.00
631.10
0.01
0.01
0.00
631.20
0.02
0.02
0.00
631.30
0.04
0.04
0.00
631.40
0.05
0.05
0.00
631.50
0.06
0.06
0.00
631.60
0.07
0.07
0.00
631.70
0.08
0.08
0.00
631.80
0.10
0.10
0.00
631.90
0.11
0.11
0.00
632.00
0.12
0.12
0.00
632.10
0.12
0.12
0.00
632.20
0.13
0.13
0.00
632.30
0.13
0.13
0.00
632.40
0.14
0.14
0.00
632.50
0.14
0.14
0.00
632.60
0.15
0.15
0.00
632.70
0.15
0.15
0.00
632.80
0.16
0.16
0.00
632.90
0.16
0.16
0.00
633.00
0.17
0.17
0.00
633.10
0.20
0.20
0.00
633.20
0.29
0.29
0.00
633.30
0.41
0.41
0.00
633.40
0.55
0.55
0.00
633.50
0.66
0.66
0.00
633.60
0.76
0.76
0.00
633.70
0.84
0.84
0.00
633.80
0.91
0.91
0.00
633.90
0.97
0.97
0.00
634.00
1.03
1.03
0.00
634.10
1.09
1.09
0.00
634.20
1.15
1.15
0.00
634.30
1.20
1.20
0.00
634.40
1.25
1.25
0.00
634.50
1.30
1.30
0.00
634.60
1.34
1.34
0.00
634.70
1.39
1.39
0.00
634.80
1.43
1.43
0.00
634.90
1.47
1.47
0.00
635.00
1.51
1.51
0.00
635.10
1.55
1.55
0.00
635.20
1.59
1.59
0.00
635.30
1.63
1.63
0.00
635.40
1.67
1.67
0.00
635.50
1.71
1.71
0.00
635.60
1.74
1.74
0.00
635.70
1.78
1.78
0.00
635.80
1.81
1.81
0.00
635.90
1.85
1.85
0.00
636.00
1.88
1.88
0.00
636.10
2.95
2.95
0.00
Elevation Discharge Primary Secondary
(feet)
(cfs)
(cfs)
(cfs)
636.20
4.87
4.87
0.00
636.30
7.35
7.35
0.00
636.40
10.28
10.28
0.00
636.50
13.60
13.60
0.00
636.60
17.27
17.27
0.00
636.70
21.25
21.25
0.00
636.80
23.69
23.69
0.00
636.90
23.84
23.84
0.00
637.00
23.99
23.99
0.00
637.10
24.99
24.14
0.85
637.20
26.69
24.29
2.40
637.30
28.86
24.44
4.42
637.40
31.42
24.59
6.83
637.50
34.28
24.73
9.55
637.60
37.43
24.88
12.55
637.70
40.66
25.03
15.64
637.80
44.06
25.17
18.89
637.90
47.81
25.31
22.50
638.00
51.76
25.46
26.30

2020.17-BM P4
Type // 24-hr 50-yr Concord Rainfall=6.80"
Prepared by {enter your company name here} Page 38
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Stage -Area -Storage for Pond 3P: (BMP-4)
Elevation
Surface
Storage
(feet)
(sq-ft)
(cubic -feet)
631.00
10,175
0
631.10
10,312
1,024
631.20
10,449
2,062
631.30
10,586
3,114
631.40
10,723
4,180
631.50
10,860
5,259
631.60
10,996
6,351
631.70
11,133
7,458
631.80
11,270
8,578
631.90
11,407
9,712
632.00
11,544
10,860
632.10
11,690
12,021
632.20
11,836
13,197
632.30
11,982
14,388
632.40
12,127
15,594
632.50
12,273
16,814
632.60
12,419
18,048
632.70
12,565
19,298
632.80
12,711
20,561
632.90
12,857
21,840
633.00
13,003
23,133
633.10
13,148
24,440
633.20
13,294
25,762
633.30
13,440
27,099
633.40
13,586
28,450
633.50
13,732
29,816
633.60
13,878
31,197
633.70
14,023
32,592
633.80
14,169
34,001
633.90
14,315
35,426
634.00
14,461
36,865
634.10
14,618
38,318
634.20
14,775
39,788
634.30
14,932
41,274
634.40
15,090
42,775
634.50
15,247
44,291
634.60
15,404
45,824
634.70
15,561
47,372
634.80
15,718
48,936
634.90
15,875
50,516
635.00
16,033
52,111
635.10
16,190
53,722
635.20
16,347
55,349
635.30
16,504
56,992
635.40
16,661
58,650
635.50
16,818
60,324
635.60
16,975
62,014
635.70
17,133
63,719
635.80
17,290
65,440
635.90
17,447
67,177
636.00
17,604
68,930
636.10
17,811
70,700
Elevation
Surface
Storage
(feet)
(sq-ft)
(cubic -feet)
636.20
18,017
72,492
636.30
18,224
74,304
636.40
18,431
76,136
636.50
18,637
77,990
636.60
18,844
79,864
636.70
19,051
81,759
636.80
19,257
83,674
636.90
19,464
85,610
637.00
19,671
87,567
637.10
19,877
89,544
637.20
20,084
91,542
637.30
20,290
93,561
637.40
20,497
95,600
637.50
20,704
97,660
637.60
20,910
99,741
637.70
21,117
101,842
637.80
21,324
103,964
637.90
21,530
106,107
638.00
21,737
108,271

SAND FILTER-5
:.� 4.. .. : . �nov
py
n uEwoua i _. _
. � . ` a• PEc umaora�rs {xrP,� . ' � r
..... "` .�.
r#m�vArrtxwr.
__ . ..

Mt. Pleasant, NC
Sand Filter Calculation
1. Calculate Runoff Coeff, (Rv)
Drainage area to filter, Ad =
Impervious area to filter forebay=
Impervious percentage =
Rv = 0.05 + 0.9(la) _
2. Calculate req'd water quality volume (WQV)
Brighton Park
5
8.05 ac
3.14 ac.
39.05%
0.40147374
Storage:
Cum
Elev.
Area
Vol.
Vol
613
7471
0
0
614
8936
8203.5
8203.5
616
12392
21328
29531.5
618
16637
29029
58560.5
620
21739
38376
96936.5
Calculate Depth for WQ Volume:
614
8203.5
614.33
11732
616
29531.5
Elevation of WQ Volume = 614.33
3. Convert Water Quality Volume, WQv to inches of runoff.
WQv = 1.0(Rv) = 0.40 inches
4. Site Hydrologic Input Parameters:
WQV = (Rv/1 x Ad/1 x 43560 sf/1 ac x Rd/1 x ft/12 in)
WQV = 11732 cf (used to size Af)
WQV= 0.2693 ac-ft.
Cn Pre = 76.0
Cn Post = 83.0 to pond

Table 4.8.3 Results of Hvdrolooic Calculations from HvdroCad
Condition
Q 1- ear
Q 10- r.
Q 25- r
Q 50 yr
Runoff
Pre Dev.
5.41
17.65
23.26
28.41
Post. Dev.
20.45
47.42
58.70
68.75
Routed
0.63
8.95
26.12
28.66
Peak Stage
615.58
617.37
617.82
618.27
Disch. Time
1163 hours
1
1
11.7' Freeboard
Required
5. First 1/2 inch 0.34 ac-ft 14610.75 cf
Detain 18 hrs 22666 cf Provided
36 hrs 16272 cf
Release Peak-36 hrs 23659 cf Provided
6. Channel Protection Volume: CPv to be held for 24 hours + 12 hours = 36 hours
S = 1000/Cn-10 where Cn = 83.0
S = 2.05 inches
Compute total runoff for the 1-year, 24-hour storm event. Total rainfall depth is
Qd = (P-0.2S)^2/(P+0.8S) 2.9 1-year storm
Qd= 1.37 inches
Watershed Runoff = (Qd)(DA)(1 ft/12") = 0.92 ac-ft. = 1.065 per Hydro -CAD
From HydroCad- Max Release Rate = 0.63 cfs
From HydroCad: Maximum Stage: 615.58
Storage: 21274 cf
Drawdown Time: 163 hours
7. Sedimentation Basin Surface Area
Min As = 0.20 x WQV = As = 2346 sf
8. Sand Filter Bed Surface Area (Af)
1093 sf
Af = (WQV x df)/(k x t x (ha + df) ha = average head
df = 1.5 (depth of filter media)
hmax = 1.33
OK
Calculate Ha = hmax/2 = 0.67 ft
Where df = depth of filter bed (15), k = permeability of sand (3.5), ha = avg depth, t=51 hrs=2.125 days
Af = 1093 sf 159.53 cf/hr = 0.044313 cfs
hmax = 1.330848181 11732 cf/(As + Af)
Choose As + Af = 3439 sf
Per plan, As = 7555
Af = 3408
Total 10963 OK

9. Sand Filter Drawdown Calculation
Coeff. Of Permeability of filter media = 3.5ft/day = 0.146 ft/hr
Volume of water drained in one hour = 0.146 ft/hr x Af s.f. = 159.5269 cf/hour
Drawdown Time = WQV/Drawdown Rate = 73.54 hrs 3.064182 days
Underdrain Calculations:
Provide 6" perforated pvc pipe with 3/8" perforations spaces 3" o.c. - 4 longitudinal rows
spaced 90 degrees apart.
71 I.f. of pipe
71 I.f. x 4 rows/ft x 4 holes/ft = 1136 holes
50% of perforations = 568 holes
Capacity of one hole = 0.0083 cfs based upon CA(2gh)^0.5
Total Capacity = 4.7144 cfs which is 106.4 times the capacity of the sand filter.
Total Capacityof 6" PVC @ 0.50% is 0.40 cfs (0.20 cfs assuming 50% clogged) from Mannings and BMP Manual.
10. Antiflotation Calculation
7 Height of Riser, ft.
6 Area of Riser, s.f.
42 Volume of Riser, c.f.
2620.8 Weight of Water @ 62.4 pcf
2882.88 Weight of water with safety factor of 1.1
82.6 Buoyant Wt. of Concrete = (145-62.4) pcf
1.29 Volume of Concrete Req'd in c.y.
34.90 Volume of Concrete Req'd in c.f.
42 Volume of Concrete in Structure (cf)
-7.10 Volume of Concrete Required (cf) (If negative, additional concrete weight not required)
0.5 ft thick
2.7 Length/Width

Brighton Park
Mt. Pleasant, NC
1. Develop Stage -Discharge Data for Sand Filter Media.
From 4.8.18 of the BMP Standards Manual:
Q = Af(k)(h+df)/(df)
Latham -Walters Engineering, Inc.
16507-A Northcross Drive
Huntersville, NC 28078
where Af = surface area of filter bed = sf
df = filter bed depth, ft. = ft.
k = coefficient of permeability of filter media (ft/day) = ft/day
h = average height of water above filter bed (ft) 12, etc.
h
Q
cf/day
Q
cfs
1
4994.2
0.058
2
6991.88
0.081
3
8989.561
0.104
4
10987.24
0.127
5
12984.92
0.150
6
14982.6
0.173
7
16980.28
0.197
8
18977.96
0.220
9
20975.64
0.243
10
22973.32
0.266

is
(Predeveloped)
(Post Developed)
Subcat Reach on Link
(BMP5)

2020.17-BM P5
Prepared by {enter your company name here} Page 2
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Area Listing (all nodes)
Area (acres) CN Description (subcats)
8.050 73 Woods, Fair, HSG C (1 S)
8.050 83 RM-2 (C) (2S)
iiM. tell]

2020.17-BMP5 Type 11 24-hr 1-yr Concord Rainfall=2.90"
Prepared by {enter your company name here} Page 3
HvdroCAD® 8.00 s/n 004317 © 2006 HvdroCAD Software Solutions LLC 6/5/2022
Time span=0.00-200.00 hrs, dt=0.01 hrs, 20001 points
Runoff by SCS TR-20 method, UH=SCS
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment 1S: (Predeveloped) Runoff Area=8.050 ac Runoff Depth=0.80"
Flow Length=487' Tc=26.5 min CN=73 Runoff=5.41 cfs 0.534 of
Subcatchment 2S: (Post Developed) Runoff Area=8.050 ac Runoff Depth=1.37"
Tc=5.0 min CN=83 Runoff=20.45 cfs 0.917 of
Pond 3P: (BMP5) Peak Elev=615.58' Storage=24,425 cf Inflow=20.45 cfs 0.917 of
Primary=0.63 cfs 0.911 of Secondary=0.00 cfs 0.000 of Outflow=0.63 cfs 0.911 of
Total Runoff Area = 16.100 ac Runoff Volume = 1.451 of Average Runoff Depth = 1.08"
100.00% Pervious Area = 16.100 ac 0.00% Impervious Area = 0.000 ac

2020.17-BM P5
Type 11 24-hr 1-yr Concord Rainfall=2.90"
Prepared by {enter your company name here} Page 4
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Subcatchment 1S: (Predeveloped)
BASED ON EXISTING CONDITIONS
Runoff = 5.41 cfs @ 12.22 hrs, Volume= 0.534 af, Depth= 0.80"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Type II 24-hr 1-yr Concord Rainfall=2.90"
Area (ac) CN Description
8.050 73 Woods, Fair, HSG C
8.050 Pervious Area
Tc
Length
Slope
Velocity
Capacity Description
(min)
(feet)
(ft/ft)
(ft/sec)
(cfs)
22.5
100
0.0637
0.07
Sheet Flow,
Woods: Dense underbrush n= 0.800 P2= 3.50"
4.0
387
0.1050
1.62
Shallow Concentrated Flow,
Woodland Kv= 5.0 fps

2020.17-BM P5
Type // 24-hr 1-yr Concord Rainfall=2.90"
Prepared by {enter your company name here} Page 5
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Hydrograph for Subcatchment 1S: (Predeveloped)
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
0.00
0.00
0.00
0.00
2.00
0.06
0.00
0.00
4.00
0.14
0.00
0.00
6.00
0.23
0.00
0.00
8.00
0.35
0.00
0.00
10.00
0.52
0.00
0.00
12.00
1.92
0.29
1.95
14.00
2.38
0.50
0.55
16.00
2.55
0.60
0.33
18.00
2.67
0.66
0.25
20.00
2.76
0.71
0.19
22.00
2.83
0.76
0.17
24.00
2.90
0.80
0.16
26.00
2.90
0.80
0.00
28.00
2.90
0.80
0.00
30.00
2.90
0.80
0.00
32.00
2.90
0.80
0.00
34.00
2.90
0.80
0.00
36.00
2.90
0.80
0.00
38.00
2.90
0.80
0.00
40.00
2.90
0.80
0.00
42.00
2.90
0.80
0.00
44.00
2.90
0.80
0.00
46.00
2.90
0.80
0.00
48.00
2.90
0.80
0.00
50.00
2.90
0.80
0.00
52.00
2.90
0.80
0.00
54.00
2.90
0.80
0.00
56.00
2.90
0.80
0.00
58.00
2.90
0.80
0.00
60.00
2.90
0.80
0.00
62.00
2.90
0.80
0.00
64.00
2.90
0.80
0.00
66.00
2.90
0.80
0.00
68.00
2.90
0.80
0.00
70.00
2.90
0.80
0.00
72.00
2.90
0.80
0.00
74.00
2.90
0.80
0.00
76.00
2.90
0.80
0.00
78.00
2.90
0.80
0.00
80.00
2.90
0.80
0.00
82.00
2.90
0.80
0.00
84.00
2.90
0.80
0.00
86.00
2.90
0.80
0.00
88.00
2.90
0.80
0.00
90.00
2.90
0.80
0.00
92.00
2.90
0.80
0.00
94.00
2.90
0.80
0.00
96.00
2.90
0.80
0.00
98.00
2.90
0.80
0.00
100.00
2.90
0.80
0.00
102.00
2.90
0.80
0.00
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
104.00
2.90
0.80
0.00
106.00
2.90
0.80
0.00
108.00
2.90
0.80
0.00
110.00
2.90
0.80
0.00
112.00
2.90
0.80
0.00
114.00
2.90
0.80
0.00
116.00
2.90
0.80
0.00
118.00
2.90
0.80
0.00
120.00
2.90
0.80
0.00
122.00
2.90
0.80
0.00
124.00
2.90
0.80
0.00
126.00
2.90
0.80
0.00
128.00
2.90
0.80
0.00
130.00
2.90
0.80
0.00
132.00
2.90
0.80
0.00
134.00
2.90
0.80
0.00
136.00
2.90
0.80
0.00
138.00
2.90
0.80
0.00
140.00
2.90
0.80
0.00
142.00
2.90
0.80
0.00
144.00
2.90
0.80
0.00
146.00
2.90
0.80
0.00
148.00
2.90
0.80
0.00
150.00
2.90
0.80
0.00
152.00
2.90
0.80
0.00
154.00
2.90
0.80
0.00
156.00
2.90
0.80
0.00
158.00
2.90
0.80
0.00
160.00
2.90
0.80
0.00
162.00
2.90
0.80
0.00
164.00
2.90
0.80
0.00
166.00
2.90
0.80
0.00
168.00
2.90
0.80
0.00
170.00
2.90
0.80
0.00
172.00
2.90
0.80
0.00
174.00
2.90
0.80
0.00
176.00
2.90
0.80
0.00
178.00
2.90
0.80
0.00
180.00
2.90
0.80
0.00
182.00
2.90
0.80
0.00
184.00
2.90
0.80
0.00
186.00
2.90
0.80
0.00
188.00
2.90
0.80
0.00
190.00
2.90
0.80
0.00
192.00
2.90
0.80
0.00
194.00
2.90
0.80
0.00
196.00
2.90
0.80
0.00
198.00
2.90
0.80
0.00
200.00
2.90
0.80
0.00

2020.17-BM P5 Type 11 24-hr 1-yr Concord Rainfall=2.90"
Prepared by {enter your company name here} Page 6
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Subcatchment 2S: (Post Developed)
Runoff = 20.45 cfs @ 11.96 hrs, Volume= 0.917 af, Depth= 1.37"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Type II 24-hr 1-yr Concord Rainfall=2.90"
Area (ac) CN Description
8.050 83 RM-2 (C)
8.050 Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,

2020.17-BM P5
Type // 24-hr 1-yr Concord Rainfall=2.90"
Prepared by {enter your company name here} Page 7
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Hydrograph for Subcatchment 2S: (Post Developed)
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
0.00
0.00
0.00
0.00
2.00
0.06
0.00
0.00
4.00
0.14
0.00
0.00
6.00
0.23
0.00
0.00
8.00
0.35
0.00
0.00
10.00
0.52
0.01
0.09
12.00
1.92
0.64
17.73
14.00
2.38
0.96
0.67
16.00
2.55
1.10
0.42
18.00
2.67
1.19
0.33
20.00
2.76
1.26
0.24
22.00
2.83
1.31
0.22
24.00
2.90
1.37
0.21
26.00
2.90
1.37
0.00
28.00
2.90
1.37
0.00
30.00
2.90
1.37
0.00
32.00
2.90
1.37
0.00
34.00
2.90
1.37
0.00
36.00
2.90
1.37
0.00
38.00
2.90
1.37
0.00
40.00
2.90
1.37
0.00
42.00
2.90
1.37
0.00
44.00
2.90
1.37
0.00
46.00
2.90
1.37
0.00
48.00
2.90
1.37
0.00
50.00
2.90
1.37
0.00
52.00
2.90
1.37
0.00
54.00
2.90
1.37
0.00
56.00
2.90
1.37
0.00
58.00
2.90
1.37
0.00
60.00
2.90
1.37
0.00
62.00
2.90
1.37
0.00
64.00
2.90
1.37
0.00
66.00
2.90
1.37
0.00
68.00
2.90
1.37
0.00
70.00
2.90
1.37
0.00
72.00
2.90
1.37
0.00
74.00
2.90
1.37
0.00
76.00
2.90
1.37
0.00
78.00
2.90
1.37
0.00
80.00
2.90
1.37
0.00
82.00
2.90
1.37
0.00
84.00
2.90
1.37
0.00
86.00
2.90
1.37
0.00
88.00
2.90
1.37
0.00
90.00
2.90
1.37
0.00
92.00
2.90
1.37
0.00
94.00
2.90
1.37
0.00
96.00
2.90
1.37
0.00
98.00
2.90
1.37
0.00
100.00
2.90
1.37
0.00
102.00
2.90
1.37
0.00
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
104.00
2.90
1.37
0.00
106.00
2.90
1.37
0.00
108.00
2.90
1.37
0.00
110.00
2.90
1.37
0.00
112.00
2.90
1.37
0.00
114.00
2.90
1.37
0.00
116.00
2.90
1.37
0.00
118.00
2.90
1.37
0.00
120.00
2.90
1.37
0.00
122.00
2.90
1.37
0.00
124.00
2.90
1.37
0.00
126.00
2.90
1.37
0.00
128.00
2.90
1.37
0.00
130.00
2.90
1.37
0.00
132.00
2.90
1.37
0.00
134.00
2.90
1.37
0.00
136.00
2.90
1.37
0.00
138.00
2.90
1.37
0.00
140.00
2.90
1.37
0.00
142.00
2.90
1.37
0.00
144.00
2.90
1.37
0.00
146.00
2.90
1.37
0.00
148.00
2.90
1.37
0.00
150.00
2.90
1.37
0.00
152.00
2.90
1.37
0.00
154.00
2.90
1.37
0.00
156.00
2.90
1.37
0.00
158.00
2.90
1.37
0.00
160.00
2.90
1.37
0.00
162.00
2.90
1.37
0.00
164.00
2.90
1.37
0.00
166.00
2.90
1.37
0.00
168.00
2.90
1.37
0.00
170.00
2.90
1.37
0.00
172.00
2.90
1.37
0.00
174.00
2.90
1.37
0.00
176.00
2.90
1.37
0.00
178.00
2.90
1.37
0.00
180.00
2.90
1.37
0.00
182.00
2.90
1.37
0.00
184.00
2.90
1.37
0.00
186.00
2.90
1.37
0.00
188.00
2.90
1.37
0.00
190.00
2.90
1.37
0.00
192.00
2.90
1.37
0.00
194.00
2.90
1.37
0.00
196.00
2.90
1.37
0.00
198.00
2.90
1.37
0.00
200.00
2.90
1.37
0.00

2020.17-BM P5
Type 11 24-hr 1-yr Concord Rainfall=2.90"
Prepared by {enter your company name here} Page 8
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Pond 3P: (BMP5)
Inflow Area = 8.050 ac, Inflow Depth = 1.37" for 1-yr Concord event
Inflow =
20.45 cfs @
11.96 hrs,
Volume=
0.917 of
Outflow =
0.63 cfs @
14.18 hrs,
Volume=
0.911 af, Atten= 97%, Lag= 133.2 min
Primary =
0.63 cfs @
14.18 hrs,
Volume=
0.911 of
Secondary =
0.00 cfs @
0.00 hrs,
Volume=
0.000 of
Routing by Stor-Ind method, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Peak Elev= 615.58' @ 14.18 hrs Surf.Area= 11,658 sf Storage= 24,425 cf
Plug -Flow detention time= 1,736.7 min calculated for 0.911 of (99% of inflow)
Center -of -Mass det. time= 1,733.5 min ( 2,567.1 - 833.5 )
Volume Invert
Avail.Storage Storage Description
#1 613.00'
96,937 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area
Inc.Store Cum.Store
(feet)
(sq-ft)
(cubic -feet) (cubic -feet)
613.00
7,472
0 0
614.00
8,936
8,204 8,204
616.00
12,392
21,328 29,532
618.00
16,637
29,029 58,561
620.00
21,739
38,376 96,937
Device Routing
Invert
Outlet Devices
#1 Primary
604.50'
18.0" x 89.0' long Culvert RCP, square edge headwall, Ke= 0.500
Outlet Invert= 604.00' S= 0.0056 7' Cc= 0.900 n= 0.013
#2 Device 1
613.00'
Exfiltration
Head (feet) 0.00 1.00 2.00 3.00 4.00 5.00 6.00
Disch. (cfs) 0.000 0.058 0.081 0.104 0.127 0.150 0.173
#3 Device 1
615.00'
6.0" Vert. Orifice/Grate C= 0.600
#4 Device 1
617.00'
2.00' x 3.00' Horiz. Top of Riser Limited to weir flow C= 0.600
#5 Secondary
618.50'
10.0' long x 16.0' breadth Spillway
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Coef. (English) 2.68 2.70 2.70 2.64 2.63 2.64 2.64 2.63
Primary OutFlow Max=0.63 cfs @ 14.18 hrs HW=615.58' (Free Discharge)
L1=Culvert (Passes 0.63 cfs of 25.45 cfs potential flow)
2=Exfltration (Custom Controls 0.09 cfs)
3=Orifice/Grate (Orifice Controls 0.54 cfs @ 2.75 fps)
=Top of Riser ( Controls 0.00 cfs)
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=613.00' (Free Discharge)
5=Spillway ( Controls 0.00 cfs)

2020.17-BM P5
Type // 24-hr 1-yr Concord Rainfall=2.90"
Prepared by {enter your company name here} Page 9
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Hydrograph for Pond 3P: (BMP5)
Time
Inflow
Storage
Elevation
Outflow
Primary
Secondary
(hours)
(cfs)
(cubic -feet)
(feet)
(cfs)
(cfs)
(cfs)
0.00
0.00
0
613.00
0.00
0.00
0.00
5.00
0.00
0
613.00
0.00
0.00
0.00
10.00
0.09
152
613.02
0.00
0.00
0.00
15.00
0.54
24,300
615.56
0.62
0.62
0.00
20.00
0.24
21,692
615.34
0.37
0.37
0.00
25.00
0.00
19,954
615.18
0.18
0.18
0.00
30.00
0.00
17,980
615.00
0.08
0.08
0.00
35.00
0.00
16,551
614.86
0.08
0.08
0.00
40.00
0.00
15,177
614.73
0.07
0.07
0.00
45.00
0.00
13,859
614.60
0.07
0.07
0.00
50.00
0.00
12,594
614.47
0.07
0.07
0.00
55.00
0.00
11,381
614.34
0.07
0.07
0.00
60.00
0.00
10,221
614.22
0.06
0.06
0.00
65.00
0.00
9,110
614.10
0.06
0.06
0.00
70.00
0.00
8,050
613.98
0.06
0.06
0.00
75.00
0.00
7,082
613.87
0.05
0.05
0.00
80.00
0.00
6,223
613.77
0.04
0.04
0.00
85.00
0.00
5,462
613.68
0.04
0.04
0.00
90.00
0.00
4,790
613.61
0.04
0.04
0.00
95.00
0.00
4,196
613.53
0.03
0.03
0.00
100.00
0.00
3,673
613.47
0.03
0.03
0.00
105.00
0.00
3,213
613.41
0.02
0.02
0.00
110.00
0.00
2,808
613.36
0.02
0.02
0.00
115.00
0.00
2,453
613.32
0.02
0.02
0.00
120.00
0.00
2,142
613.28
0.02
0.02
0.00
125.00
0.00
1,869
613.24
0.01
0.01
0.00
130.00
0.00
1,630
613.21
0.01
0.01
0.00
135.00
0.00
1,422
613.19
0.01
0.01
0.00
140.00
0.00
1,239
613.16
0.01
0.01
0.00
145.00
0.00
1,080
613.14
0.01
0.01
0.00
150.00
0.00
941
613.12
0.01
0.01
0.00
155.00
0.00
820
613.11
0.01
0.01
0.00
160.00
0.00
714
613.09
0.01
0.01
0.00
165.00
0.00
622
613.08
0.00
0.00
0.00
170.00
0.00
541
613.07
0.00
0.00
0.00
175.00
0.00
471
613.06
0.00
0.00
0.00
180.00
0.00
410
613.05
0.00
0.00
0.00
185.00
0.00
357
613.05
0.00
0.00
0.00
190.00
0.00
311
613.04
0.00
0.00
0.00
195.00
0.00
270
613.04
0.00
0.00
0.00
200.00
0.00
235
613.03
0.00
0.00
0.00

2020.17-BM P5
Type 11 24-hr 1-yr Concord Rainfall=2.90"
Prepared by {enter your company name here} Page 10
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Stage -Discharge for Pond 3P: (BMP5)
Elevation Discharge Primary Secondary
(feet)
(cfs)
(cfs)
(cfs)
613.00
0.00
0.00
0.00
613.10
0.01
0.01
0.00
613.20
0.01
0.01
0.00
613.30
0.02
0.02
0.00
613.40
0.02
0.02
0.00
613.50
0.03
0.03
0.00
613.60
0.03
0.03
0.00
613.70
0.04
0.04
0.00
613.80
0.05
0.05
0.00
613.90
0.05
0.05
0.00
614.00
0.06
0.06
0.00
614.10
0.06
0.06
0.00
614.20
0.06
0.06
0.00
614.30
0.06
0.06
0.00
614.40
0.07
0.07
0.00
614.50
0.07
0.07
0.00
614.60
0.07
0.07
0.00
614.70
0.07
0.07
0.00
614.80
0.08
0.08
0.00
614.90
0.08
0.08
0.00
615.00
0.08
0.08
0.00
615.10
0.11
0.11
0.00
615.20
0.20
0.20
0.00
615.30
0.32
0.32
0.00
615.40
0.45
0.45
0.00
615.50
0.57
0.57
0.00
615.60
0.65
0.65
0.00
615.70
0.73
0.73
0.00
615.80
0.80
0.80
0.00
615.90
0.86
0.86
0.00
616.00
0.92
0.92
0.00
616.10
0.98
0.98
0.00
616.20
1.03
1.03
0.00
616.30
1.08
1.08
0.00
616.40
1.13
1.13
0.00
616.50
1.17
1.17
0.00
616.60
1.22
1.22
0.00
616.70
1.26
1.26
0.00
616.80
1.30
1.30
0.00
616.90
1.34
1.34
0.00
617.00
1.38
1.38
0.00
617.10
2.45
2.45
0.00
617.20
4.38
4.38
0.00
617.30
6.86
6.86
0.00
617.40
9.79
9.79
0.00
617.50
13.12
13.12
0.00
617.60
16.79
16.79
0.00
617.70
20.77
20.77
0.00
617.80
25.05
25.05
0.00
617.90
28.24
28.24
0.00
618.00
28.35
28.35
0.00
618.10
28.46
28.46
0.00
Elevation Discharge Primary Secondary
(feet)
(cfs)
(cfs)
(cfs)
618.20
28.58
28.58
0.00
618.30
28.69
28.69
0.00
618.40
28.80
28.80
0.00
618.50
28.91
28.91
0.00
618.60
29.87
29.02
0.85
618.70
31.53
29.13
2.40
618.80
33.66
29.24
4.42
618.90
36.18
29.35
6.83
619.00
39.01
29.46
9.55
619.10
42.12
29.57
12.55
619.20
45.32
29.68
15.64
619.30
48.68
29.79
18.89
619.40
52.39
29.90
22.50
619.50
56.30
30.00
26.30
619.60
60.51
30.11
30.40
619.70
64.92
30.22
34.70
619.80
69.45
30.32
39.13
619.90
74.16
30.43
43.73
620.00
78.94
30.53
48.41

2020.17-BM P5
Type 11 24-hr 1-yr Concord Rainfall=2.90"
Prepared by {enter your company name here} Page 11
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Stage -Area -Storage for Pond 3P: (BMP5)
Elevation
Surface
Storage
(feet)
(sq-ft)
(cubic -feet)
613.00
7,472
0
613.10
7,618
755
613.20
7,765
1,524
613.30
7,911
2,307
613.40
8,058
3,106
613.50
8,204
3,919
613.60
8,350
4,747
613.70
8,497
5,589
613.80
8,643
6,446
613.90
8,790
7,318
614.00
8,936
8,204
614.10
9,109
9,106
614.20
9,282
10,026
614.30
9,454
10,963
614.40
9,627
11,917
614.50
9,800
12,888
614.60
9,973
13,877
614.70
10,146
14,883
614.80
10,318
15,906
614.90
10,491
16,946
615.00
10,664
18,004
615.10
10,837
19,079
615.20
11,010
20,171
615.30
11,182
21,281
615.40
11,355
22,408
615.50
11,528
23,552
615.60
11,701
24,713
615.70
11,874
25,892
615.80
12,046
27,088
615.90
12,219
28,301
616.00
12,392
29,532
616.10
12,604
30,782
616.20
12,817
32,053
616.30
13,029
33,345
616.40
13,241
34,659
616.50
13,453
35,993
616.60
13,666
37,349
616.70
13,878
38,726
616.80
14,090
40,125
616.90
14,302
41,544
617.00
14,515
42,985
617.10
14,727
44,447
617.20
14,939
45,931
617.30
15,151
47,435
617.40
15,363
48,961
617.50
15,576
50,508
617.60
15,788
52,076
617.70
16,000
53,665
617.80
16,212
55,276
617.90
16,425
56,908
618.00
16,637
58,561
618.10
16,892
60,237
Elevation
Surface
Storage
(feet)
(sq-ft)
(cubic -feet)
618.20
17,147
61,939
618.30
17,402
63,667
618.40
17,657
65,420
618.50
17,913
67,198
618.60
18,168
69,002
618.70
18,423
70,832
618.80
18,678
72,687
618.90
18,933
74,567
619.00
19,188
76,474
619.10
19,443
78,405
619.20
19,698
80,362
619.30
19,953
82,345
619.40
20,208
84,353
619.50
20,464
86,386
619.60
20,719
88,445
619.70
20,974
90,530
619.80
21,229
92,640
619.90
21,484
94,776
620.00
21,739
96,937

2020.17-BM P5 Type 11 24-hr 10-yr Concord Rainfall=5.10"
Prepared by {enter your company name here} Page 12
HvdroCAD® 8.00 s/n 004317 © 2006 HvdroCAD Software Solutions LLC 6/5/2022
Time span=0.00-200.00 hrs, dt=0.01 hrs, 20001 points
Runoff by SCS TR-20 method, UH=SCS
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment 1S: (Predeveloped) Runoff Area=8.050 ac Runoff Depth=2.36"
Flow Length=487' Tc=26.5 min CN=73 Runoff=17.65 cfs 1.583 of
Subcatchment 2S: (Post Developed) Runoff Area=8.050 ac Runoff Depth=3.26"
Tc=5.0 min CN=83 Runoff=47.42 cfs 2.190 of
Pond 3P: (BMPS) Peak Elev=617.37' Storage=48,530 cf Inflow=47.42 cfs 2.190 of
Primary=8.95 cfs 2.184 of Secondary=0.00 cfs 0.000 of Outflow=8.95 cfs 2.184 of
Total Runoff Area = 16.100 ac Runoff Volume = 3.773 of Average Runoff Depth = 2.81"
100.00% Pervious Area = 16.100 ac 0.00% Impervious Area = 0.000 ac

2020.17-BM P5
Type 11 24-hr 10-yr Concord Rainfall=5.10"
Prepared by {enter your company name here} Page 13
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Subcatchment 1S: (Predeveloped)
BASED ON EXISTING CONDITIONS
Runoff = 17.65 cfs @ 12.22 hrs, Volume= 1.583 af, Depth= 2.36"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Type II 24-hr 10-yr Concord Rainfall=5.10"
Area (ac) CN Description
8.050 73 Woods, Fair, HSG C
8.050 Pervious Area
Tc
Length
Slope
Velocity
Capacity Description
(min)
(feet)
(ft/ft)
(ft/sec)
(cfs)
22.5
100
0.0637
0.07
Sheet Flow,
Woods: Dense underbrush n= 0.800 P2= 3.50"
4.0
387
0.1050
1.62
Shallow Concentrated Flow,
Woodland Kv= 5.0 fps

2020.17-BM P5
Type 11 24-hr 10-yr Concord Rainfall=5.10"
Prepared by {enter your company name here} Page 14
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Hydrograph for Subcatchment 1S: (Predeveloped)
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
0.00
0.00
0.00
0.00
2.00
0.11
0.00
0.00
4.00
0.24
0.00
0.00
6.00
0.41
0.00
0.00
8.00
0.61
0.00
0.00
10.00
0.92
0.01
0.08
12.00
3.38
1.10
8.51
14.00
4.18
1.66
1.37
16.00
4.49
1.89
0.80
18.00
4.70
2.05
0.60
20.00
4.86
2.17
0.45
22.00
4.98
2.27
0.40
24.00
5.10
2.36
0.37
26.00
5.10
2.36
0.00
28.00
5.10
2.36
0.00
30.00
5.10
2.36
0.00
32.00
5.10
2.36
0.00
34.00
5.10
2.36
0.00
36.00
5.10
2.36
0.00
38.00
5.10
2.36
0.00
40.00
5.10
2.36
0.00
42.00
5.10
2.36
0.00
44.00
5.10
2.36
0.00
46.00
5.10
2.36
0.00
48.00
5.10
2.36
0.00
50.00
5.10
2.36
0.00
52.00
5.10
2.36
0.00
54.00
5.10
2.36
0.00
56.00
5.10
2.36
0.00
58.00
5.10
2.36
0.00
60.00
5.10
2.36
0.00
62.00
5.10
2.36
0.00
64.00
5.10
2.36
0.00
66.00
5.10
2.36
0.00
68.00
5.10
2.36
0.00
70.00
5.10
2.36
0.00
72.00
5.10
2.36
0.00
74.00
5.10
2.36
0.00
76.00
5.10
2.36
0.00
78.00
5.10
2.36
0.00
80.00
5.10
2.36
0.00
82.00
5.10
2.36
0.00
84.00
5.10
2.36
0.00
86.00
5.10
2.36
0.00
88.00
5.10
2.36
0.00
90.00
5.10
2.36
0.00
92.00
5.10
2.36
0.00
94.00
5.10
2.36
0.00
96.00
5.10
2.36
0.00
98.00
5.10
2.36
0.00
100.00
5.10
2.36
0.00
102.00
5.10
2.36
0.00
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
104.00
5.10
2.36
0.00
106.00
5.10
2.36
0.00
108.00
5.10
2.36
0.00
110.00
5.10
2.36
0.00
112.00
5.10
2.36
0.00
114.00
5.10
2.36
0.00
116.00
5.10
2.36
0.00
118.00
5.10
2.36
0.00
120.00
5.10
2.36
0.00
122.00
5.10
2.36
0.00
124.00
5.10
2.36
0.00
126.00
5.10
2.36
0.00
128.00
5.10
2.36
0.00
130.00
5.10
2.36
0.00
132.00
5.10
2.36
0.00
134.00
5.10
2.36
0.00
136.00
5.10
2.36
0.00
138.00
5.10
2.36
0.00
140.00
5.10
2.36
0.00
142.00
5.10
2.36
0.00
144.00
5.10
2.36
0.00
146.00
5.10
2.36
0.00
148.00
5.10
2.36
0.00
150.00
5.10
2.36
0.00
152.00
5.10
2.36
0.00
154.00
5.10
2.36
0.00
156.00
5.10
2.36
0.00
158.00
5.10
2.36
0.00
160.00
5.10
2.36
0.00
162.00
5.10
2.36
0.00
164.00
5.10
2.36
0.00
166.00
5.10
2.36
0.00
168.00
5.10
2.36
0.00
170.00
5.10
2.36
0.00
172.00
5.10
2.36
0.00
174.00
5.10
2.36
0.00
176.00
5.10
2.36
0.00
178.00
5.10
2.36
0.00
180.00
5.10
2.36
0.00
182.00
5.10
2.36
0.00
184.00
5.10
2.36
0.00
186.00
5.10
2.36
0.00
188.00
5.10
2.36
0.00
190.00
5.10
2.36
0.00
192.00
5.10
2.36
0.00
194.00
5.10
2.36
0.00
196.00
5.10
2.36
0.00
198.00
5.10
2.36
0.00
200.00
5.10
2.36
0.00

2020.17-BM P5
Type 11 24-hr 10-yr Concord Rainfall=5.10"
Prepared by {enter your company name here} Page 15
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Subcatchment 2S: (Post Developed)
Runoff = 47.42 cfs @ 11.96 hrs, Volume= 2.190 af, Depth= 3.26"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Type II 24-hr 10-yr Concord Rainfall=5.10"
Area (ac) CN Description
8.050 83 RM-2 (C)
8.050 Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,

2020.17-BM P5
Type 11 24-hr 10-yr Concord Rainfall=5.10"
Prepared by {enter your company name here} Page 16
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Hydrograph for Subcatchment 2S: (Post Developed)
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
0.00
0.00
0.00
0.00
2.00
0.11
0.00
0.00
4.00
0.24
0.00
0.00
6.00
0.41
0.00
0.00
8.00
0.61
0.02
0.15
10.00
0.92
0.10
0.57
12.00
3.38
1.76
40.18
14.00
4.18
2.44
1.40
16.00
4.49
2.71
0.87
18.00
4.70
2.90
0.67
20.00
4.86
3.04
0.49
22.00
4.98
3.16
0.45
24.00
5.10
3.26
0.41
26.00
5.10
3.26
0.00
28.00
5.10
3.26
0.00
30.00
5.10
3.26
0.00
32.00
5.10
3.26
0.00
34.00
5.10
3.26
0.00
36.00
5.10
3.26
0.00
38.00
5.10
3.26
0.00
40.00
5.10
3.26
0.00
42.00
5.10
3.26
0.00
44.00
5.10
3.26
0.00
46.00
5.10
3.26
0.00
48.00
5.10
3.26
0.00
50.00
5.10
3.26
0.00
52.00
5.10
3.26
0.00
54.00
5.10
3.26
0.00
56.00
5.10
3.26
0.00
58.00
5.10
3.26
0.00
60.00
5.10
3.26
0.00
62.00
5.10
3.26
0.00
64.00
5.10
3.26
0.00
66.00
5.10
3.26
0.00
68.00
5.10
3.26
0.00
70.00
5.10
3.26
0.00
72.00
5.10
3.26
0.00
74.00
5.10
3.26
0.00
76.00
5.10
3.26
0.00
78.00
5.10
3.26
0.00
80.00
5.10
3.26
0.00
82.00
5.10
3.26
0.00
84.00
5.10
3.26
0.00
86.00
5.10
3.26
0.00
88.00
5.10
3.26
0.00
90.00
5.10
3.26
0.00
92.00
5.10
3.26
0.00
94.00
5.10
3.26
0.00
96.00
5.10
3.26
0.00
98.00
5.10
3.26
0.00
100.00
5.10
3.26
0.00
102.00
5.10
3.26
0.00
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
104.00
5.10
3.26
0.00
106.00
5.10
3.26
0.00
108.00
5.10
3.26
0.00
110.00
5.10
3.26
0.00
112.00
5.10
3.26
0.00
114.00
5.10
3.26
0.00
116.00
5.10
3.26
0.00
118.00
5.10
3.26
0.00
120.00
5.10
3.26
0.00
122.00
5.10
3.26
0.00
124.00
5.10
3.26
0.00
126.00
5.10
3.26
0.00
128.00
5.10
3.26
0.00
130.00
5.10
3.26
0.00
132.00
5.10
3.26
0.00
134.00
5.10
3.26
0.00
136.00
5.10
3.26
0.00
138.00
5.10
3.26
0.00
140.00
5.10
3.26
0.00
142.00
5.10
3.26
0.00
144.00
5.10
3.26
0.00
146.00
5.10
3.26
0.00
148.00
5.10
3.26
0.00
150.00
5.10
3.26
0.00
152.00
5.10
3.26
0.00
154.00
5.10
3.26
0.00
156.00
5.10
3.26
0.00
158.00
5.10
3.26
0.00
160.00
5.10
3.26
0.00
162.00
5.10
3.26
0.00
164.00
5.10
3.26
0.00
166.00
5.10
3.26
0.00
168.00
5.10
3.26
0.00
170.00
5.10
3.26
0.00
172.00
5.10
3.26
0.00
174.00
5.10
3.26
0.00
176.00
5.10
3.26
0.00
178.00
5.10
3.26
0.00
180.00
5.10
3.26
0.00
182.00
5.10
3.26
0.00
184.00
5.10
3.26
0.00
186.00
5.10
3.26
0.00
188.00
5.10
3.26
0.00
190.00
5.10
3.26
0.00
192.00
5.10
3.26
0.00
194.00
5.10
3.26
0.00
196.00
5.10
3.26
0.00
198.00
5.10
3.26
0.00
200.00
5.10
3.26
0.00

2020.17-BM P5
Type 11 24-hr 10-yr Concord Rainfall=5.10"
Prepared by {enter your company name here} Page 17
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Pond 3P: (BMP5)
Inflow Area = 8.050 ac, Inflow Depth = 3.26" for 10-yr Concord event
Inflow =
47.42 cfs @
11.96 hrs,
Volume=
2.190 of
Outflow =
8.95 cfs @
12.11 hrs,
Volume=
2.184 af, Atten= 81 %, Lag= 9.2 min
Primary =
8.95 cfs @
12.11 hrs,
Volume=
2.184 of
Secondary =
0.00 cfs @
0.00 hrs,
Volume=
0.000 of
Routing by Stor-Ind method, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Peak Elev= 617.37' @ 12.11 hrs Surf.Area= 15,304 sf Storage= 48,530 cf
Plug -Flow detention time= 891.5 min calculated for 2.184 of (100% of inflow)
Center -of -Mass det. time= 889.8 min ( 1,698.5 - 808.6 )
Volume Invert
Avail.Storage Storage Description
#1 613.00'
96,937 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area
Inc.Store Cum.Store
(feet)
(sq-ft)
(cubic -feet) (cubic -feet)
613.00
7,472
0 0
614.00
8,936
8,204 8,204
616.00
12,392
21,328 29,532
618.00
16,637
29,029 58,561
620.00
21,739
38,376 96,937
Device Routing
Invert
Outlet Devices
#1 Primary
604.50'
18.0" x 89.0' long Culvert RCP, square edge headwall, Ke= 0.500
Outlet Invert= 604.00' S= 0.0056 7' Cc= 0.900 n= 0.013
#2 Device 1
613.00'
Exfiltration
Head (feet) 0.00 1.00 2.00 3.00 4.00 5.00 6.00
Disch. (cfs) 0.000 0.058 0.081 0.104 0.127 0.150 0.173
#3 Device 1
615.00'
6.0" Vert. Orifice/Grate C= 0.600
#4 Device 1
617.00'
2.00' x 3.00' Horiz. Top of Riser Limited to weir flow C= 0.600
#5 Secondary
618.50'
10.0' long x 16.0' breadth Spillway
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Coef. (English) 2.68 2.70 2.70 2.64 2.63 2.64 2.64 2.63
Primary OutFlow Max=8.92 cfs @ 12.11 hrs HW=617.37' (Free Discharge)
L1=Culvert (Passes 8.92 cfs of 27.63 cfs potential flow)
2=Exfltration (Custom Controls 0.14 cfs)
3=Orifice/Grate (Orifice Controls 1.38 cfs @ 7.01 fps)
=Top of Riser (Weir Controls 7.41 cfs @ 1.99 fps)
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=613.00' (Free Discharge)
5=Spillway ( Controls 0.00 cfs)

2020.17-BM P5
Type 11 24-hr 10-yr Concord Rainfall=5.10"
Prepared by {enter your company name here} Page 18
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Hydrograph for Pond 3P: (BMP5)
Time
Inflow
Storage
Elevation
Outflow
Primary
Secondary
(hours)
(cfs)
(cubic -feet)
(feet)
(cfs)
(cfs)
(cfs)
0.00
0.00
0
613.00
0.00
0.00
0.00
5.00
0.00
0
613.00
0.00
0.00
0.00
10.00
0.57
2,762
613.36
0.02
0.02
0.00
15.00
1.12
42,715
616.98
1.37
1.37
0.00
20.00
0.49
33,524
616.31
1.09
1.09
0.00
25.00
0.00
24,231
615.56
0.62
0.62
0.00
30.00
0.00
19,086
615.10
0.11
0.11
0.00
35.00
0.00
17,490
614.95
0.08
0.08
0.00
40.00
0.00
16,080
614.82
0.08
0.08
0.00
45.00
0.00
14,725
614.68
0.07
0.07
0.00
50.00
0.00
13,425
614.55
0.07
0.07
0.00
55.00
0.00
12,178
614.43
0.07
0.07
0.00
60.00
0.00
10,983
614.30
0.06
0.06
0.00
65.00
0.00
9,839
614.18
0.06
0.06
0.00
70.00
0.00
8,746
614.06
0.06
0.06
0.00
75.00
0.00
7,710
613.94
0.05
0.05
0.00
80.00
0.00
6,780
613.84
0.05
0.05
0.00
85.00
0.00
5,955
613.74
0.04
0.04
0.00
90.00
0.00
5,225
613.66
0.04
0.04
0.00
95.00
0.00
4,581
613.58
0.03
0.03
0.00
100.00
0.00
4,012
613.51
0.03
0.03
0.00
105.00
0.00
3,511
613.45
0.03
0.03
0.00
110.00
0.00
3,070
613.40
0.02
0.02
0.00
115.00
0.00
2,683
613.35
0.02
0.02
0.00
120.00
0.00
2,343
613.30
0.02
0.02
0.00
125.00
0.00
2,045
613.27
0.02
0.02
0.00
130.00
0.00
1,785
613.23
0.01
0.01
0.00
135.00
0.00
1,557
613.20
0.01
0.01
0.00
140.00
0.00
1,357
613.18
0.01
0.01
0.00
145.00
0.00
1,183
613.16
0.01
0.01
0.00
150.00
0.00
1,031
613.14
0.01
0.01
0.00
155.00
0.00
898
613.12
0.01
0.01
0.00
160.00
0.00
782
613.10
0.01
0.01
0.00
165.00
0.00
681
613.09
0.01
0.01
0.00
170.00
0.00
593
613.08
0.00
0.00
0.00
175.00
0.00
516
613.07
0.00
0.00
0.00
180.00
0.00
449
613.06
0.00
0.00
0.00
185.00
0.00
391
613.05
0.00
0.00
0.00
190.00
0.00
340
613.05
0.00
0.00
0.00
195.00
0.00
296
613.04
0.00
0.00
0.00
200.00
0.00
258
613.03
0.00
0.00
0.00

2020.17-BM P5
Type 11 24-hr 10-yr Concord Rainfall=5.10"
Prepared by {enter your company name here} Page 19
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Stage -Discharge for Pond 3P: (BMP5)
Elevation Discharge Primary Secondary
(feet)
(cfs)
(cfs)
(cfs)
613.00
0.00
0.00
0.00
613.10
0.01
0.01
0.00
613.20
0.01
0.01
0.00
613.30
0.02
0.02
0.00
613.40
0.02
0.02
0.00
613.50
0.03
0.03
0.00
613.60
0.03
0.03
0.00
613.70
0.04
0.04
0.00
613.80
0.05
0.05
0.00
613.90
0.05
0.05
0.00
614.00
0.06
0.06
0.00
614.10
0.06
0.06
0.00
614.20
0.06
0.06
0.00
614.30
0.06
0.06
0.00
614.40
0.07
0.07
0.00
614.50
0.07
0.07
0.00
614.60
0.07
0.07
0.00
614.70
0.07
0.07
0.00
614.80
0.08
0.08
0.00
614.90
0.08
0.08
0.00
615.00
0.08
0.08
0.00
615.10
0.11
0.11
0.00
615.20
0.20
0.20
0.00
615.30
0.32
0.32
0.00
615.40
0.45
0.45
0.00
615.50
0.57
0.57
0.00
615.60
0.65
0.65
0.00
615.70
0.73
0.73
0.00
615.80
0.80
0.80
0.00
615.90
0.86
0.86
0.00
616.00
0.92
0.92
0.00
616.10
0.98
0.98
0.00
616.20
1.03
1.03
0.00
616.30
1.08
1.08
0.00
616.40
1.13
1.13
0.00
616.50
1.17
1.17
0.00
616.60
1.22
1.22
0.00
616.70
1.26
1.26
0.00
616.80
1.30
1.30
0.00
616.90
1.34
1.34
0.00
617.00
1.38
1.38
0.00
617.10
2.45
2.45
0.00
617.20
4.38
4.38
0.00
617.30
6.86
6.86
0.00
617.40
9.79
9.79
0.00
617.50
13.12
13.12
0.00
617.60
16.79
16.79
0.00
617.70
20.77
20.77
0.00
617.80
25.05
25.05
0.00
617.90
28.24
28.24
0.00
618.00
28.35
28.35
0.00
618.10
28.46
28.46
0.00
Elevation Discharge Primary Secondary
(feet)
(cfs)
(cfs)
(cfs)
618.20
28.58
28.58
0.00
618.30
28.69
28.69
0.00
618.40
28.80
28.80
0.00
618.50
28.91
28.91
0.00
618.60
29.87
29.02
0.85
618.70
31.53
29.13
2.40
618.80
33.66
29.24
4.42
618.90
36.18
29.35
6.83
619.00
39.01
29.46
9.55
619.10
42.12
29.57
12.55
619.20
45.32
29.68
15.64
619.30
48.68
29.79
18.89
619.40
52.39
29.90
22.50
619.50
56.30
30.00
26.30
619.60
60.51
30.11
30.40
619.70
64.92
30.22
34.70
619.80
69.45
30.32
39.13
619.90
74.16
30.43
43.73
620.00
78.94
30.53
48.41

2020.17-BM P5
Type // 24-hr 10-yr Concord Rainfall=5.10"
Prepared by {enter your company name here} Page 20
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Stage -Area -Storage for Pond 3P: (BMP5)
Elevation
Surface
Storage
(feet)
(sq-ft)
(cubic -feet)
613.00
7,472
0
613.10
7,618
755
613.20
7,765
1,524
613.30
7,911
2,307
613.40
8,058
3,106
613.50
8,204
3,919
613.60
8,350
4,747
613.70
8,497
5,589
613.80
8,643
6,446
613.90
8,790
7,318
614.00
8,936
8,204
614.10
9,109
9,106
614.20
9,282
10,026
614.30
9,454
10,963
614.40
9,627
11,917
614.50
9,800
12,888
614.60
9,973
13,877
614.70
10,146
14,883
614.80
10,318
15,906
614.90
10,491
16,946
615.00
10,664
18,004
615.10
10,837
19,079
615.20
11,010
20,171
615.30
11,182
21,281
615.40
11,355
22,408
615.50
11,528
23,552
615.60
11,701
24,713
615.70
11,874
25,892
615.80
12,046
27,088
615.90
12,219
28,301
616.00
12,392
29,532
616.10
12,604
30,782
616.20
12,817
32,053
616.30
13,029
33,345
616.40
13,241
34,659
616.50
13,453
35,993
616.60
13,666
37,349
616.70
13,878
38,726
616.80
14,090
40,125
616.90
14,302
41,544
617.00
14,515
42,985
617.10
14,727
44,447
617.20
14,939
45,931
617.30
15,151
47,435
617.40
15,363
48,961
617.50
15,576
50,508
617.60
15,788
52,076
617.70
16,000
53,665
617.80
16,212
55,276
617.90
16,425
56,908
618.00
16,637
58,561
618.10
16,892
60,237
Elevation
Surface
Storage
(feet)
(sq-ft)
(cubic -feet)
618.20
17,147
61,939
618.30
17,402
63,667
618.40
17,657
65,420
618.50
17,913
67,198
618.60
18,168
69,002
618.70
18,423
70,832
618.80
18,678
72,687
618.90
18,933
74,567
619.00
19,188
76,474
619.10
19,443
78,405
619.20
19,698
80,362
619.30
19,953
82,345
619.40
20,208
84,353
619.50
20,464
86,386
619.60
20,719
88,445
619.70
20,974
90,530
619.80
21,229
92,640
619.90
21,484
94,776
620.00
21,739
96,937

2020.17-BM P5 Type/1 24-hr 25-yr Concord Rainfall=6.00"
Prepared by {enter your company name here} Page 21
HvdroCAD® 8.00 s/n 004317 © 2006 HvdroCAD Software Solutions LLC 6/5/2022
Time span=0.00-200.00 hrs, dt=0.01 hrs, 20001 points
Runoff by SCS TR-20 method, UH=SCS
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment 1S: (Predeveloped) Runoff Area=8.050 ac Runoff Depth=3.09"
Flow Length=487' Tc=26.5 min CN=73 Runoff=23.26 cfs 2.072 of
Subcatchment 2S: (Post Developed) Runoff Area=8.050 ac Runoff Depth=4.09"
Tc=5.0 min CN=83 Runoff=58.70 cfs 2.745 of
Pond 3P: (BMPS) Peak Elev=617.82' Storage=55,662 cf Inflow=58.70 cfs 2.745 of
Primary=26.12 cfs 2.739 of Secondary=0.00 cfs 0.000 of Outflow=26.12 cfs 2.739 of
Total Runoff Area = 16.100 ac Runoff Volume = 4.817 of Average Runoff Depth = 3.59"
100.00% Pervious Area = 16.100 ac 0.00% Impervious Area = 0.000 ac

2020.17-BM P5
Type/1 24-hr 25-yr Concord Rainfall=6.00"
Prepared by {enter your company name here} Page 22
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Subcatchment 1S: (Predeveloped)
BASED ON EXISTING CONDITIONS
Runoff = 23.26 cfs @ 12.21 hrs, Volume= 2.072 af, Depth= 3.09"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Type II 24-hr 25-yr Concord Rainfall=6.00"
Area (ac) CN Description
8.050 73 Woods, Fair, HSG C
8.050 Pervious Area
Tc
Length
Slope
Velocity
Capacity Description
(min)
(feet)
(ft/ft)
(ft/sec)
(cfs)
22.5
100
0.0637
0.07
Sheet Flow,
Woods: Dense underbrush n= 0.800 P2= 3.50"
4.0
387
0.1050
1.62
Shallow Concentrated Flow,
Woodland Kv= 5.0 fps

2020.17-BM P5
Type // 24-hr 25-yr Concord Rainfall=6.00"
Prepared by {enter your company name here} Page 23
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Hydrograph for Subcatchment 1S: (Predeveloped)
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
0.00
0.00
0.00
0.00
2.00
0.13
0.00
0.00
4.00
0.29
0.00
0.00
6.00
0.48
0.00
0.00
8.00
0.72
0.00
0.00
10.00
1.09
0.03
0.21
12.00
3.98
1.51
11.67
14.00
4.92
2.22
1.72
16.00
5.28
2.50
1.00
18.00
5.53
2.70
0.75
20.00
5.71
2.85
0.56
22.00
5.86
2.97
0.49
24.00
6.00
3.09
0.45
26.00
6.00
3.09
0.00
28.00
6.00
3.09
0.00
30.00
6.00
3.09
0.00
32.00
6.00
3.09
0.00
34.00
6.00
3.09
0.00
36.00
6.00
3.09
0.00
38.00
6.00
3.09
0.00
40.00
6.00
3.09
0.00
42.00
6.00
3.09
0.00
44.00
6.00
3.09
0.00
46.00
6.00
3.09
0.00
48.00
6.00
3.09
0.00
50.00
6.00
3.09
0.00
52.00
6.00
3.09
0.00
54.00
6.00
3.09
0.00
56.00
6.00
3.09
0.00
58.00
6.00
3.09
0.00
60.00
6.00
3.09
0.00
62.00
6.00
3.09
0.00
64.00
6.00
3.09
0.00
66.00
6.00
3.09
0.00
68.00
6.00
3.09
0.00
70.00
6.00
3.09
0.00
72.00
6.00
3.09
0.00
74.00
6.00
3.09
0.00
76.00
6.00
3.09
0.00
78.00
6.00
3.09
0.00
80.00
6.00
3.09
0.00
82.00
6.00
3.09
0.00
84.00
6.00
3.09
0.00
86.00
6.00
3.09
0.00
88.00
6.00
3.09
0.00
90.00
6.00
3.09
0.00
92.00
6.00
3.09
0.00
94.00
6.00
3.09
0.00
96.00
6.00
3.09
0.00
98.00
6.00
3.09
0.00
100.00
6.00
3.09
0.00
102.00
6.00
3.09
0.00
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
104.00
6.00
3.09
0.00
106.00
6.00
3.09
0.00
108.00
6.00
3.09
0.00
110.00
6.00
3.09
0.00
112.00
6.00
3.09
0.00
114.00
6.00
3.09
0.00
116.00
6.00
3.09
0.00
118.00
6.00
3.09
0.00
120.00
6.00
3.09
0.00
122.00
6.00
3.09
0.00
124.00
6.00
3.09
0.00
126.00
6.00
3.09
0.00
128.00
6.00
3.09
0.00
130.00
6.00
3.09
0.00
132.00
6.00
3.09
0.00
134.00
6.00
3.09
0.00
136.00
6.00
3.09
0.00
138.00
6.00
3.09
0.00
140.00
6.00
3.09
0.00
142.00
6.00
3.09
0.00
144.00
6.00
3.09
0.00
146.00
6.00
3.09
0.00
148.00
6.00
3.09
0.00
150.00
6.00
3.09
0.00
152.00
6.00
3.09
0.00
154.00
6.00
3.09
0.00
156.00
6.00
3.09
0.00
158.00
6.00
3.09
0.00
160.00
6.00
3.09
0.00
162.00
6.00
3.09
0.00
164.00
6.00
3.09
0.00
166.00
6.00
3.09
0.00
168.00
6.00
3.09
0.00
170.00
6.00
3.09
0.00
172.00
6.00
3.09
0.00
174.00
6.00
3.09
0.00
176.00
6.00
3.09
0.00
178.00
6.00
3.09
0.00
180.00
6.00
3.09
0.00
182.00
6.00
3.09
0.00
184.00
6.00
3.09
0.00
186.00
6.00
3.09
0.00
188.00
6.00
3.09
0.00
190.00
6.00
3.09
0.00
192.00
6.00
3.09
0.00
194.00
6.00
3.09
0.00
196.00
6.00
3.09
0.00
198.00
6.00
3.09
0.00
200.00
6.00
3.09
0.00

2020.17-BM P5
Type/1 24-hr 25-yr Concord Rainfall=6.00"
Prepared by {enter your company name here} Page 24
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Subcatchment 2S: (Post Developed)
Runoff = 58.70 cfs @ 11.96 hrs, Volume= 2.745 af, Depth= 4.09"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Type II 24-hr 25-yr Concord Rainfall=6.00"
Area (ac) CN Description
8.050 83 RM-2 (C)
8.050 Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,

2020.17-BM P5
Type // 24-hr 25-yr Concord Rainfall=6.00"
Prepared by {enter your company name here} Page 25
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Hydrograph for Subcatchment 2S: (Post Developed)
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
0.00
0.00
0.00
0.00
2.00
0.13
0.00
0.00
4.00
0.29
0.00
0.00
6.00
0.48
0.00
0.05
8.00
0.72
0.04
0.25
10.00
1.09
0.17
0.81
12.00
3.98
2.27
49.51
14.00
4.92
3.10
1.69
16.00
5.28
3.43
1.05
18.00
5.53
3.65
0.81
20.00
5.71
3.82
0.59
22.00
5.86
3.96
0.54
24.00
6.00
4.09
0.50
26.00
6.00
4.09
0.00
28.00
6.00
4.09
0.00
30.00
6.00
4.09
0.00
32.00
6.00
4.09
0.00
34.00
6.00
4.09
0.00
36.00
6.00
4.09
0.00
38.00
6.00
4.09
0.00
40.00
6.00
4.09
0.00
42.00
6.00
4.09
0.00
44.00
6.00
4.09
0.00
46.00
6.00
4.09
0.00
48.00
6.00
4.09
0.00
50.00
6.00
4.09
0.00
52.00
6.00
4.09
0.00
54.00
6.00
4.09
0.00
56.00
6.00
4.09
0.00
58.00
6.00
4.09
0.00
60.00
6.00
4.09
0.00
62.00
6.00
4.09
0.00
64.00
6.00
4.09
0.00
66.00
6.00
4.09
0.00
68.00
6.00
4.09
0.00
70.00
6.00
4.09
0.00
72.00
6.00
4.09
0.00
74.00
6.00
4.09
0.00
76.00
6.00
4.09
0.00
78.00
6.00
4.09
0.00
80.00
6.00
4.09
0.00
82.00
6.00
4.09
0.00
84.00
6.00
4.09
0.00
86.00
6.00
4.09
0.00
88.00
6.00
4.09
0.00
90.00
6.00
4.09
0.00
92.00
6.00
4.09
0.00
94.00
6.00
4.09
0.00
96.00
6.00
4.09
0.00
98.00
6.00
4.09
0.00
100.00
6.00
4.09
0.00
102.00
6.00
4.09
0.00
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
104.00
6.00
4.09
0.00
106.00
6.00
4.09
0.00
108.00
6.00
4.09
0.00
110.00
6.00
4.09
0.00
112.00
6.00
4.09
0.00
114.00
6.00
4.09
0.00
116.00
6.00
4.09
0.00
118.00
6.00
4.09
0.00
120.00
6.00
4.09
0.00
122.00
6.00
4.09
0.00
124.00
6.00
4.09
0.00
126.00
6.00
4.09
0.00
128.00
6.00
4.09
0.00
130.00
6.00
4.09
0.00
132.00
6.00
4.09
0.00
134.00
6.00
4.09
0.00
136.00
6.00
4.09
0.00
138.00
6.00
4.09
0.00
140.00
6.00
4.09
0.00
142.00
6.00
4.09
0.00
144.00
6.00
4.09
0.00
146.00
6.00
4.09
0.00
148.00
6.00
4.09
0.00
150.00
6.00
4.09
0.00
152.00
6.00
4.09
0.00
154.00
6.00
4.09
0.00
156.00
6.00
4.09
0.00
158.00
6.00
4.09
0.00
160.00
6.00
4.09
0.00
162.00
6.00
4.09
0.00
164.00
6.00
4.09
0.00
166.00
6.00
4.09
0.00
168.00
6.00
4.09
0.00
170.00
6.00
4.09
0.00
172.00
6.00
4.09
0.00
174.00
6.00
4.09
0.00
176.00
6.00
4.09
0.00
178.00
6.00
4.09
0.00
180.00
6.00
4.09
0.00
182.00
6.00
4.09
0.00
184.00
6.00
4.09
0.00
186.00
6.00
4.09
0.00
188.00
6.00
4.09
0.00
190.00
6.00
4.09
0.00
192.00
6.00
4.09
0.00
194.00
6.00
4.09
0.00
196.00
6.00
4.09
0.00
198.00
6.00
4.09
0.00
200.00
6.00
4.09
0.00

2020.17-BM P5
Type/1 24-hr 25-yr Concord Rainfall=6.00"
Prepared by {enter your company name here} Page 26
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Pond 3P: (BMP5)
Inflow Area = 8.050 ac, Inflow Depth = 4.09" for 25-yr Concord event
Inflow =
58.70 cfs @
11.96 hrs,
Volume=
2.745 of
Outflow =
26.12 cfs @
12.05 hrs,
Volume=
2.739 af, Atten= 56%, Lag= 5.4 min
Primary =
26.12 cfs @
12.05 hrs,
Volume=
2.739 of
Secondary =
0.00 cfs @
0.00 hrs,
Volume=
0.000 of
Routing by Stor-Ind method, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Peak Elev= 617.82' @ 12.05 hrs Surf.Area= 16,263 sf Storage= 55,662 cf
Plug -Flow detention time= 735.9 min calculated for 2.739 of (100% of inflow)
Center -of -Mass det. time= 734.5 min ( 1,536.7 - 802.2 )
Volume Invert
Avail.Storage Storage Description
#1 613.00'
96,937 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area
Inc.Store Cum.Store
(feet)
(sq-ft)
(cubic -feet) (cubic -feet)
613.00
7,472
0 0
614.00
8,936
8,204 8,204
616.00
12,392
21,328 29,532
618.00
16,637
29,029 58,561
620.00
21,739
38,376 96,937
Device Routing
Invert
Outlet Devices
#1 Primary
604.50'
18.0" x 89.0' long Culvert RCP, square edge headwall, Ke= 0.500
Outlet Invert= 604.00' S= 0.0056 7' Cc= 0.900 n= 0.013
#2 Device 1
613.00'
Exfiltration
Head (feet) 0.00 1.00 2.00 3.00 4.00 5.00 6.00
Disch. (cfs) 0.000 0.058 0.081 0.104 0.127 0.150 0.173
#3 Device 1
615.00'
6.0" Vert. Orifice/Grate C= 0.600
#4 Device 1
617.00'
2.00' x 3.00' Horiz. Top of Riser Limited to weir flow C= 0.600
#5 Secondary
618.50'
10.0' long x 16.0' breadth Spillway
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Coef. (English) 2.68 2.70 2.70 2.64 2.63 2.64 2.64 2.63
Primary OutFlow Max=26.11 cfs @ 12.05 hrs HW=617.82' (Free Discharge)
L1=Culvert (Passes 26.11 cfs of 28.15 cfs potential flow)
2=Exfltration (Custom Controls 0.15 cfs)
3=Orifice/Grate (Orifice Controls 1.52 cfs @ 7.72 fps)
=Top of Riser (Weir Controls 24.45 cfs @ 2.97 fps)
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=613.00' (Free Discharge)
5=Spillway ( Controls 0.00 cfs)

2020.17-BM P5
Type // 24-hr 25-yr Concord Rainfall=6.00"
Prepared by {enter your company name here} Page 27
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Hydrograph for Pond 3P: (BMP5)
Time
Inflow
Storage
Elevation
Outflow
Primary
Secondary
(hours)
(cfs)
(cubic -feet)
(feet)
(cfs)
(cfs)
(cfs)
0.00
0.00
0
613.00
0.00
0.00
0.00
5.00
0.00
0
613.00
0.00
0.00
0.00
10.00
0.81
4,517
613.57
0.03
0.03
0.00
15.00
1.35
43,217
617.02
1.51
1.51
0.00
20.00
0.59
35,797
616.49
1.17
1.17
0.00
25.00
0.00
26,018
615.71
0.74
0.74
0.00
30.00
0.00
19,415
615.13
0.14
0.14
0.00
35.00
0.00
17,701
614.97
0.08
0.08
0.00
40.00
0.00
16,283
614.84
0.08
0.08
0.00
45.00
0.00
14,920
614.70
0.07
0.07
0.00
50.00
0.00
13,612
614.57
0.07
0.07
0.00
55.00
0.00
12,357
614.45
0.07
0.07
0.00
60.00
0.00
11,154
614.32
0.07
0.07
0.00
65.00
0.00
10,003
614.20
0.06
0.06
0.00
70.00
0.00
8,903
614.08
0.06
0.06
0.00
75.00
0.00
7,855
613.96
0.06
0.06
0.00
80.00
0.00
6,909
613.85
0.05
0.05
0.00
85.00
0.00
6,070
613.76
0.04
0.04
0.00
90.00
0.00
5,327
613.67
0.04
0.04
0.00
95.00
0.00
4,670
613.59
0.03
0.03
0.00
100.00
0.00
4,090
613.52
0.03
0.03
0.00
105.00
0.00
3,580
613.46
0.03
0.03
0.00
110.00
0.00
3,131
613.40
0.02
0.02
0.00
115.00
0.00
2,736
613.35
0.02
0.02
0.00
120.00
0.00
2,390
613.31
0.02
0.02
0.00
125.00
0.00
2,086
613.27
0.02
0.02
0.00
130.00
0.00
1,821
613.24
0.01
0.01
0.00
135.00
0.00
1,588
613.21
0.01
0.01
0.00
140.00
0.00
1,385
613.18
0.01
0.01
0.00
145.00
0.00
1,207
613.16
0.01
0.01
0.00
150.00
0.00
1,052
613.14
0.01
0.01
0.00
155.00
0.00
916
613.12
0.01
0.01
0.00
160.00
0.00
798
613.11
0.01
0.01
0.00
165.00
0.00
695
613.09
0.01
0.01
0.00
170.00
0.00
605
613.08
0.00
0.00
0.00
175.00
0.00
527
613.07
0.00
0.00
0.00
180.00
0.00
459
613.06
0.00
0.00
0.00
185.00
0.00
399
613.05
0.00
0.00
0.00
190.00
0.00
347
613.05
0.00
0.00
0.00
195.00
0.00
302
613.04
0.00
0.00
0.00
200.00
0.00
263
613.03
0.00
0.00
0.00

2020.17-BM P5
Type // 24-hr 25-yr Concord Rainfall=6.00"
Prepared by {enter your company name here} Page 28
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Stage -Discharge for Pond 3P: (BMP5)
Elevation Discharge Primary Secondary
(feet)
(cfs)
(cfs)
(cfs)
613.00
0.00
0.00
0.00
613.10
0.01
0.01
0.00
613.20
0.01
0.01
0.00
613.30
0.02
0.02
0.00
613.40
0.02
0.02
0.00
613.50
0.03
0.03
0.00
613.60
0.03
0.03
0.00
613.70
0.04
0.04
0.00
613.80
0.05
0.05
0.00
613.90
0.05
0.05
0.00
614.00
0.06
0.06
0.00
614.10
0.06
0.06
0.00
614.20
0.06
0.06
0.00
614.30
0.06
0.06
0.00
614.40
0.07
0.07
0.00
614.50
0.07
0.07
0.00
614.60
0.07
0.07
0.00
614.70
0.07
0.07
0.00
614.80
0.08
0.08
0.00
614.90
0.08
0.08
0.00
615.00
0.08
0.08
0.00
615.10
0.11
0.11
0.00
615.20
0.20
0.20
0.00
615.30
0.32
0.32
0.00
615.40
0.45
0.45
0.00
615.50
0.57
0.57
0.00
615.60
0.65
0.65
0.00
615.70
0.73
0.73
0.00
615.80
0.80
0.80
0.00
615.90
0.86
0.86
0.00
616.00
0.92
0.92
0.00
616.10
0.98
0.98
0.00
616.20
1.03
1.03
0.00
616.30
1.08
1.08
0.00
616.40
1.13
1.13
0.00
616.50
1.17
1.17
0.00
616.60
1.22
1.22
0.00
616.70
1.26
1.26
0.00
616.80
1.30
1.30
0.00
616.90
1.34
1.34
0.00
617.00
1.38
1.38
0.00
617.10
2.45
2.45
0.00
617.20
4.38
4.38
0.00
617.30
6.86
6.86
0.00
617.40
9.79
9.79
0.00
617.50
13.12
13.12
0.00
617.60
16.79
16.79
0.00
617.70
20.77
20.77
0.00
617.80
25.05
25.05
0.00
617.90
28.24
28.24
0.00
618.00
28.35
28.35
0.00
618.10
28.46
28.46
0.00
Elevation Discharge Primary Secondary
(feet)
(cfs)
(cfs)
(cfs)
618.20
28.58
28.58
0.00
618.30
28.69
28.69
0.00
618.40
28.80
28.80
0.00
618.50
28.91
28.91
0.00
618.60
29.87
29.02
0.85
618.70
31.53
29.13
2.40
618.80
33.66
29.24
4.42
618.90
36.18
29.35
6.83
619.00
39.01
29.46
9.55
619.10
42.12
29.57
12.55
619.20
45.32
29.68
15.64
619.30
48.68
29.79
18.89
619.40
52.39
29.90
22.50
619.50
56.30
30.00
26.30
619.60
60.51
30.11
30.40
619.70
64.92
30.22
34.70
619.80
69.45
30.32
39.13
619.90
74.16
30.43
43.73
620.00
78.94
30.53
48.41

2020.17-BM P5
Type // 24-hr 25-yr Concord Rainfall=6.00"
Prepared by {enter your company name here} Page 29
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Stage -Area -Storage for Pond 3P: (BMP5)
Elevation
Surface
Storage
(feet)
(sq-ft)
(cubic -feet)
613.00
7,472
0
613.10
7,618
755
613.20
7,765
1,524
613.30
7,911
2,307
613.40
8,058
3,106
613.50
8,204
3,919
613.60
8,350
4,747
613.70
8,497
5,589
613.80
8,643
6,446
613.90
8,790
7,318
614.00
8,936
8,204
614.10
9,109
9,106
614.20
9,282
10,026
614.30
9,454
10,963
614.40
9,627
11,917
614.50
9,800
12,888
614.60
9,973
13,877
614.70
10,146
14,883
614.80
10,318
15,906
614.90
10,491
16,946
615.00
10,664
18,004
615.10
10,837
19,079
615.20
11,010
20,171
615.30
11,182
21,281
615.40
11,355
22,408
615.50
11,528
23,552
615.60
11,701
24,713
615.70
11,874
25,892
615.80
12,046
27,088
615.90
12,219
28,301
616.00
12,392
29,532
616.10
12,604
30,782
616.20
12,817
32,053
616.30
13,029
33,345
616.40
13,241
34,659
616.50
13,453
35,993
616.60
13,666
37,349
616.70
13,878
38,726
616.80
14,090
40,125
616.90
14,302
41,544
617.00
14,515
42,985
617.10
14,727
44,447
617.20
14,939
45,931
617.30
15,151
47,435
617.40
15,363
48,961
617.50
15,576
50,508
617.60
15,788
52,076
617.70
16,000
53,665
617.80
16,212
55,276
617.90
16,425
56,908
618.00
16,637
58,561
618.10
16,892
60,237
Elevation
Surface
Storage
(feet)
(sq-ft)
(cubic -feet)
618.20
17,147
61,939
618.30
17,402
63,667
618.40
17,657
65,420
618.50
17,913
67,198
618.60
18,168
69,002
618.70
18,423
70,832
618.80
18,678
72,687
618.90
18,933
74,567
619.00
19,188
76,474
619.10
19,443
78,405
619.20
19,698
80,362
619.30
19,953
82,345
619.40
20,208
84,353
619.50
20,464
86,386
619.60
20,719
88,445
619.70
20,974
90,530
619.80
21,229
92,640
619.90
21,484
94,776
620.00
21,739
96,937

2020.17-BM P5 Type 11 24-hr 50-yr Concord Rainfall=6.80"
Prepared by {enter your company name here} Page 30
HvdroCAD® 8.00 s/n 004317 © 2006 HvdroCAD Software Solutions LLC 6/5/2022
Time span=0.00-200.00 hrs, dt=0.01 hrs, 20001 points
Runoff by SCS TR-20 method, UH=SCS
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment 1S: (Predeveloped) Runoff Area=8.050 ac Runoff Depth=3.76"
Flow Length=487' Tc=26.5 min CN=73 Runoff=28.41 cfs 2.525 of
Subcatchment 2S: (Post Developed) Runoff Area=8.050 ac Runoff Depth=4.84"
Tc=5.0 min CN=83 Runoff=68.75 cfs 3.246 of
Pond 3P: (BMPS) Peak Elev=618.27' Storage=63,188 cf Inflow=68.75 cfs 3.246 of
Primary=28.66 cfs 3.240 of Secondary=0.00 cfs 0.000 of Outflow=28.66 cfs 3.240 of
Total Runoff Area = 16.100 ac Runoff Volume = 5.771 of Average Runoff Depth = 4.30"
100.00% Pervious Area = 16.100 ac 0.00% Impervious Area = 0.000 ac

2020.17-BM P5
Type 11 24-hr 50-yr Concord Rainfall=6.80"
Prepared by {enter your company name here} Page 31
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Subcatchment 1S: (Predeveloped)
BASED ON EXISTING CONDITIONS
Runoff = 28.41 cfs @ 12.21 hrs, Volume= 2.525 af, Depth= 3.76"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Type II 24-hr 50-yr Concord Rainfall=6.80"
Area (ac) CN Description
8.050 73 Woods, Fair, HSG C
8.050 Pervious Area
Tc
Length
Slope
Velocity
Capacity Description
(min)
(feet)
(ft/ft)
(ft/sec)
(cfs)
22.5
100
0.0637
0.07
Sheet Flow,
Woods: Dense underbrush n= 0.800 P2= 3.50"
4.0
387
0.1050
1.62
Shallow Concentrated Flow,
Woodland Kv= 5.0 fps

2020.17-BM P5
Type // 24-hr 50-yr Concord Rainfall=6.80"
Prepared by {enter your company name here} Page 32
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Hydrograph for Subcatchment 1S: (Predeveloped)
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
0.00
0.00
0.00
0.00
2.00
0.15
0.00
0.00
4.00
0.33
0.00
0.00
6.00
0.54
0.00
0.00
8.00
0.82
0.00
0.01
10.00
1.23
0.06
0.34
12.00
4.51
1.90
14.62
14.00
5.58
2.74
2.03
16.00
5.98
3.08
1.18
18.00
6.26
3.31
0.88
20.00
6.47
3.49
0.65
22.00
6.64
3.63
0.57
24.00
6.80
3.76
0.53
26.00
6.80
3.76
0.00
28.00
6.80
3.76
0.00
30.00
6.80
3.76
0.00
32.00
6.80
3.76
0.00
34.00
6.80
3.76
0.00
36.00
6.80
3.76
0.00
38.00
6.80
3.76
0.00
40.00
6.80
3.76
0.00
42.00
6.80
3.76
0.00
44.00
6.80
3.76
0.00
46.00
6.80
3.76
0.00
48.00
6.80
3.76
0.00
50.00
6.80
3.76
0.00
52.00
6.80
3.76
0.00
54.00
6.80
3.76
0.00
56.00
6.80
3.76
0.00
58.00
6.80
3.76
0.00
60.00
6.80
3.76
0.00
62.00
6.80
3.76
0.00
64.00
6.80
3.76
0.00
66.00
6.80
3.76
0.00
68.00
6.80
3.76
0.00
70.00
6.80
3.76
0.00
72.00
6.80
3.76
0.00
74.00
6.80
3.76
0.00
76.00
6.80
3.76
0.00
78.00
6.80
3.76
0.00
80.00
6.80
3.76
0.00
82.00
6.80
3.76
0.00
84.00
6.80
3.76
0.00
86.00
6.80
3.76
0.00
88.00
6.80
3.76
0.00
90.00
6.80
3.76
0.00
92.00
6.80
3.76
0.00
94.00
6.80
3.76
0.00
96.00
6.80
3.76
0.00
98.00
6.80
3.76
0.00
100.00
6.80
3.76
0.00
102.00
6.80
3.76
0.00
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
104.00
6.80
3.76
0.00
106.00
6.80
3.76
0.00
108.00
6.80
3.76
0.00
110.00
6.80
3.76
0.00
112.00
6.80
3.76
0.00
114.00
6.80
3.76
0.00
116.00
6.80
3.76
0.00
118.00
6.80
3.76
0.00
120.00
6.80
3.76
0.00
122.00
6.80
3.76
0.00
124.00
6.80
3.76
0.00
126.00
6.80
3.76
0.00
128.00
6.80
3.76
0.00
130.00
6.80
3.76
0.00
132.00
6.80
3.76
0.00
134.00
6.80
3.76
0.00
136.00
6.80
3.76
0.00
138.00
6.80
3.76
0.00
140.00
6.80
3.76
0.00
142.00
6.80
3.76
0.00
144.00
6.80
3.76
0.00
146.00
6.80
3.76
0.00
148.00
6.80
3.76
0.00
150.00
6.80
3.76
0.00
152.00
6.80
3.76
0.00
154.00
6.80
3.76
0.00
156.00
6.80
3.76
0.00
158.00
6.80
3.76
0.00
160.00
6.80
3.76
0.00
162.00
6.80
3.76
0.00
164.00
6.80
3.76
0.00
166.00
6.80
3.76
0.00
168.00
6.80
3.76
0.00
170.00
6.80
3.76
0.00
172.00
6.80
3.76
0.00
174.00
6.80
3.76
0.00
176.00
6.80
3.76
0.00
178.00
6.80
3.76
0.00
180.00
6.80
3.76
0.00
182.00
6.80
3.76
0.00
184.00
6.80
3.76
0.00
186.00
6.80
3.76
0.00
188.00
6.80
3.76
0.00
190.00
6.80
3.76
0.00
192.00
6.80
3.76
0.00
194.00
6.80
3.76
0.00
196.00
6.80
3.76
0.00
198.00
6.80
3.76
0.00
200.00
6.80
3.76
0.00

2020.17-BM P5
Type 11 24-hr 50-yr Concord Rainfall=6.80"
Prepared by {enter your company name here} Page 33
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Subcatchment 2S: (Post Developed)
Runoff = 68.75 cfs @ 11.96 hrs, Volume= 3.246 af, Depth= 4.84"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Type II 24-hr 50-yr Concord Rainfall=6.80"
Area (ac) CN Description
8.050 83 RM-2 (C)
8.050 Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,

2020.17-BM P5
Type // 24-hr 50-yr Concord Rainfall=6.80"
Prepared by {enter your company name here} Page 34
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Hydrograph for Subcatchment 2S: (Post Developed)
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
0.00
0.00
0.00
0.00
2.00
0.15
0.00
0.00
4.00
0.33
0.00
0.00
6.00
0.54
0.01
0.11
8.00
0.82
0.07
0.36
10.00
1.23
0.24
1.03
12.00
4.51
2.73
57.79
14.00
5.58
3.70
1.95
16.00
5.98
4.08
1.21
18.00
6.26
4.34
0.94
20.00
6.47
4.53
0.68
22.00
6.64
4.69
0.62
24.00
6.80
4.84
0.57
26.00
6.80
4.84
0.00
28.00
6.80
4.84
0.00
30.00
6.80
4.84
0.00
32.00
6.80
4.84
0.00
34.00
6.80
4.84
0.00
36.00
6.80
4.84
0.00
38.00
6.80
4.84
0.00
40.00
6.80
4.84
0.00
42.00
6.80
4.84
0.00
44.00
6.80
4.84
0.00
46.00
6.80
4.84
0.00
48.00
6.80
4.84
0.00
50.00
6.80
4.84
0.00
52.00
6.80
4.84
0.00
54.00
6.80
4.84
0.00
56.00
6.80
4.84
0.00
58.00
6.80
4.84
0.00
60.00
6.80
4.84
0.00
62.00
6.80
4.84
0.00
64.00
6.80
4.84
0.00
66.00
6.80
4.84
0.00
68.00
6.80
4.84
0.00
70.00
6.80
4.84
0.00
72.00
6.80
4.84
0.00
74.00
6.80
4.84
0.00
76.00
6.80
4.84
0.00
78.00
6.80
4.84
0.00
80.00
6.80
4.84
0.00
82.00
6.80
4.84
0.00
84.00
6.80
4.84
0.00
86.00
6.80
4.84
0.00
88.00
6.80
4.84
0.00
90.00
6.80
4.84
0.00
92.00
6.80
4.84
0.00
94.00
6.80
4.84
0.00
96.00
6.80
4.84
0.00
98.00
6.80
4.84
0.00
100.00
6.80
4.84
0.00
102.00
6.80
4.84
0.00
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
104.00
6.80
4.84
0.00
106.00
6.80
4.84
0.00
108.00
6.80
4.84
0.00
110.00
6.80
4.84
0.00
112.00
6.80
4.84
0.00
114.00
6.80
4.84
0.00
116.00
6.80
4.84
0.00
118.00
6.80
4.84
0.00
120.00
6.80
4.84
0.00
122.00
6.80
4.84
0.00
124.00
6.80
4.84
0.00
126.00
6.80
4.84
0.00
128.00
6.80
4.84
0.00
130.00
6.80
4.84
0.00
132.00
6.80
4.84
0.00
134.00
6.80
4.84
0.00
136.00
6.80
4.84
0.00
138.00
6.80
4.84
0.00
140.00
6.80
4.84
0.00
142.00
6.80
4.84
0.00
144.00
6.80
4.84
0.00
146.00
6.80
4.84
0.00
148.00
6.80
4.84
0.00
150.00
6.80
4.84
0.00
152.00
6.80
4.84
0.00
154.00
6.80
4.84
0.00
156.00
6.80
4.84
0.00
158.00
6.80
4.84
0.00
160.00
6.80
4.84
0.00
162.00
6.80
4.84
0.00
164.00
6.80
4.84
0.00
166.00
6.80
4.84
0.00
168.00
6.80
4.84
0.00
170.00
6.80
4.84
0.00
172.00
6.80
4.84
0.00
174.00
6.80
4.84
0.00
176.00
6.80
4.84
0.00
178.00
6.80
4.84
0.00
180.00
6.80
4.84
0.00
182.00
6.80
4.84
0.00
184.00
6.80
4.84
0.00
186.00
6.80
4.84
0.00
188.00
6.80
4.84
0.00
190.00
6.80
4.84
0.00
192.00
6.80
4.84
0.00
194.00
6.80
4.84
0.00
196.00
6.80
4.84
0.00
198.00
6.80
4.84
0.00
200.00
6.80
4.84
0.00

2020.17-BM P5
Type 11 24-hr 50-yr Concord Rainfall=6.80"
Prepared by {enter your company name here} Page 35
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Pond 3P: (BMP5)
Inflow Area = 8.050 ac, Inflow Depth = 4.84" for 50-yr Concord event
Inflow =
68.75 cfs @
11.96 hrs,
Volume=
3.246 of
Outflow =
28.66 cfs @
12.05 hrs,
Volume=
3.240 af, Atten= 58%, Lag= 5.7 min
Primary =
28.66 cfs @
12.05 hrs,
Volume=
3.240 of
Secondary =
0.00 cfs @
0.00 hrs,
Volume=
0.000 of
Routing by Stor-Ind method, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Peak Elev= 618.27' @ 12.05 hrs Surf.Area= 17,332 sf Storage= 63,188 cf
Plug -Flow detention time= 639.2 min calculated for 3.240 of (100% of inflow)
Center -of -Mass det. time= 638.5 min ( 1,436.0 - 797.5 )
Volume Invert
Avail.Storage Storage Description
#1 613.00'
96,937 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area
Inc.Store Cum.Store
(feet)
(sq-ft)
(cubic -feet) (cubic -feet)
613.00
7,472
0 0
614.00
8,936
8,204 8,204
616.00
12,392
21,328 29,532
618.00
16,637
29,029 58,561
620.00
21,739
38,376 96,937
Device Routing
Invert
Outlet Devices
#1 Primary
604.50'
18.0" x 89.0' long Culvert RCP, square edge headwall, Ke= 0.500
Outlet Invert= 604.00' S= 0.0056 7' Cc= 0.900 n= 0.013
#2 Device 1
613.00'
Exfiltration
Head (feet) 0.00 1.00 2.00 3.00 4.00 5.00 6.00
Disch. (cfs) 0.000 0.058 0.081 0.104 0.127 0.150 0.173
#3 Device 1
615.00'
6.0" Vert. Orifice/Grate C= 0.600
#4 Device 1
617.00'
2.00' x 3.00' Horiz. Top of Riser Limited to weir flow C= 0.600
#5 Secondary
618.50'
10.0' long x 16.0' breadth Spillway
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Coef. (English) 2.68 2.70 2.70 2.64 2.63 2.64 2.64 2.63
Primary OutFlow Max=28.66 cfs @ 12.05 hrs HW=618.27' (Free Discharge)
L1=Culvert (Barrel Controls 28.66 cfs @ 16.22 fps)
2=Exfltration (Passes < 0.16 cfs potential flow)
3=Orifice/Grate (Passes < 1.64 cfs potential flow)
=Top of Riser (Passes < 32.57 cfs potential flow)
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=613.00' (Free Discharge)
5=Spillway ( Controls 0.00 cfs)

2020.17-BM P5
Type // 24-hr 50-yr Concord Rainfall=6.80"
Prepared by {enter your company name here} Page 36
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Hydrograph for Pond 3P: (BMP5)
Time
Inflow
Storage
Elevation
Outflow
Primary
Secondary
(hours)
(cfs)
(cubic -feet)
(feet)
(cfs)
(cfs)
(cfs)
0.00
0.00
0
613.00
0.00
0.00
0.00
5.00
0.01
2
613.00
0.00
0.00
0.00
10.00
1.03
6,327
613.79
0.05
0.05
0.00
15.00
1.56
43,572
617.04
1.72
1.72
0.00
20.00
0.68
37,538
616.61
1.22
1.22
0.00
25.00
0.00
27,606
615.84
0.83
0.83
0.00
30.00
0.00
19,714
615.16
0.16
0.16
0.00
35.00
0.00
17,864
614.99
0.08
0.08
0.00
40.00
0.00
16,440
614.85
0.08
0.08
0.00
45.00
0.00
15,071
614.72
0.07
0.07
0.00
50.00
0.00
13,756
614.59
0.07
0.07
0.00
55.00
0.00
12,496
614.46
0.07
0.07
0.00
60.00
0.00
11,287
614.33
0.07
0.07
0.00
65.00
0.00
10,131
614.21
0.06
0.06
0.00
70.00
0.00
9,024
614.09
0.06
0.06
0.00
75.00
0.00
7,969
613.97
0.06
0.06
0.00
80.00
0.00
7,010
613.86
0.05
0.05
0.00
85.00
0.00
6,159
613.77
0.04
0.04
0.00
90.00
0.00
5,406
613.68
0.04
0.04
0.00
95.00
0.00
4,740
613.60
0.03
0.03
0.00
100.00
0.00
4,152
613.53
0.03
0.03
0.00
105.00
0.00
3,634
613.47
0.03
0.03
0.00
110.00
0.00
3,178
613.41
0.02
0.02
0.00
115.00
0.00
2,778
613.36
0.02
0.02
0.00
120.00
0.00
2,427
613.31
0.02
0.02
0.00
125.00
0.00
2,119
613.28
0.02
0.02
0.00
130.00
0.00
1,849
613.24
0.01
0.01
0.00
135.00
0.00
1,613
613.21
0.01
0.01
0.00
140.00
0.00
1,406
613.18
0.01
0.01
0.00
145.00
0.00
1,226
613.16
0.01
0.01
0.00
150.00
0.00
1,068
613.14
0.01
0.01
0.00
155.00
0.00
931
613.12
0.01
0.01
0.00
160.00
0.00
811
613.11
0.01
0.01
0.00
165.00
0.00
706
613.09
0.01
0.01
0.00
170.00
0.00
615
613.08
0.00
0.00
0.00
175.00
0.00
535
613.07
0.00
0.00
0.00
180.00
0.00
466
613.06
0.00
0.00
0.00
185.00
0.00
405
613.05
0.00
0.00
0.00
190.00
0.00
353
613.05
0.00
0.00
0.00
195.00
0.00
307
613.04
0.00
0.00
0.00
200.00
0.00
267
613.04
0.00
0.00
0.00

2020.17-BM P5
Type // 24-hr 50-yr Concord Rainfall=6.80"
Prepared by {enter your company name here} Page 37
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Stage -Discharge for Pond 3P: (BMP5)
Elevation Discharge Primary Secondary
(feet)
(cfs)
(cfs)
(cfs)
613.00
0.00
0.00
0.00
613.10
0.01
0.01
0.00
613.20
0.01
0.01
0.00
613.30
0.02
0.02
0.00
613.40
0.02
0.02
0.00
613.50
0.03
0.03
0.00
613.60
0.03
0.03
0.00
613.70
0.04
0.04
0.00
613.80
0.05
0.05
0.00
613.90
0.05
0.05
0.00
614.00
0.06
0.06
0.00
614.10
0.06
0.06
0.00
614.20
0.06
0.06
0.00
614.30
0.06
0.06
0.00
614.40
0.07
0.07
0.00
614.50
0.07
0.07
0.00
614.60
0.07
0.07
0.00
614.70
0.07
0.07
0.00
614.80
0.08
0.08
0.00
614.90
0.08
0.08
0.00
615.00
0.08
0.08
0.00
615.10
0.11
0.11
0.00
615.20
0.20
0.20
0.00
615.30
0.32
0.32
0.00
615.40
0.45
0.45
0.00
615.50
0.57
0.57
0.00
615.60
0.65
0.65
0.00
615.70
0.73
0.73
0.00
615.80
0.80
0.80
0.00
615.90
0.86
0.86
0.00
616.00
0.92
0.92
0.00
616.10
0.98
0.98
0.00
616.20
1.03
1.03
0.00
616.30
1.08
1.08
0.00
616.40
1.13
1.13
0.00
616.50
1.17
1.17
0.00
616.60
1.22
1.22
0.00
616.70
1.26
1.26
0.00
616.80
1.30
1.30
0.00
616.90
1.34
1.34
0.00
617.00
1.38
1.38
0.00
617.10
2.45
2.45
0.00
617.20
4.38
4.38
0.00
617.30
6.86
6.86
0.00
617.40
9.79
9.79
0.00
617.50
13.12
13.12
0.00
617.60
16.79
16.79
0.00
617.70
20.77
20.77
0.00
617.80
25.05
25.05
0.00
617.90
28.24
28.24
0.00
618.00
28.35
28.35
0.00
618.10
28.46
28.46
0.00
Elevation Discharge Primary Secondary
(feet)
(cfs)
(cfs)
(cfs)
618.20
28.58
28.58
0.00
618.30
28.69
28.69
0.00
618.40
28.80
28.80
0.00
618.50
28.91
28.91
0.00
618.60
29.87
29.02
0.85
618.70
31.53
29.13
2.40
618.80
33.66
29.24
4.42
618.90
36.18
29.35
6.83
619.00
39.01
29.46
9.55
619.10
42.12
29.57
12.55
619.20
45.32
29.68
15.64
619.30
48.68
29.79
18.89
619.40
52.39
29.90
22.50
619.50
56.30
30.00
26.30
619.60
60.51
30.11
30.40
619.70
64.92
30.22
34.70
619.80
69.45
30.32
39.13
619.90
74.16
30.43
43.73
620.00
78.94
30.53
48.41

2020.17-BM P5
Type // 24-hr 50-yr Concord Rainfall=6.80"
Prepared by {enter your company name here} Page 38
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Stage -Area -Storage for Pond 3P: (BMP5)
Elevation
Surface
Storage
(feet)
(sq-ft)
(cubic -feet)
613.00
7,472
0
613.10
7,618
755
613.20
7,765
1,524
613.30
7,911
2,307
613.40
8,058
3,106
613.50
8,204
3,919
613.60
8,350
4,747
613.70
8,497
5,589
613.80
8,643
6,446
613.90
8,790
7,318
614.00
8,936
8,204
614.10
9,109
9,106
614.20
9,282
10,026
614.30
9,454
10,963
614.40
9,627
11,917
614.50
9,800
12,888
614.60
9,973
13,877
614.70
10,146
14,883
614.80
10,318
15,906
614.90
10,491
16,946
615.00
10,664
18,004
615.10
10,837
19,079
615.20
11,010
20,171
615.30
11,182
21,281
615.40
11,355
22,408
615.50
11,528
23,552
615.60
11,701
24,713
615.70
11,874
25,892
615.80
12,046
27,088
615.90
12,219
28,301
616.00
12,392
29,532
616.10
12,604
30,782
616.20
12,817
32,053
616.30
13,029
33,345
616.40
13,241
34,659
616.50
13,453
35,993
616.60
13,666
37,349
616.70
13,878
38,726
616.80
14,090
40,125
616.90
14,302
41,544
617.00
14,515
42,985
617.10
14,727
44,447
617.20
14,939
45,931
617.30
15,151
47,435
617.40
15,363
48,961
617.50
15,576
50,508
617.60
15,788
52,076
617.70
16,000
53,665
617.80
16,212
55,276
617.90
16,425
56,908
618.00
16,637
58,561
618.10
16,892
60,237
Elevation
Surface
Storage
(feet)
(sq-ft)
(cubic -feet)
618.20
17,147
61,939
618.30
17,402
63,667
618.40
17,657
65,420
618.50
17,913
67,198
618.60
18,168
69,002
618.70
18,423
70,832
618.80
18,678
72,687
618.90
18,933
74,567
619.00
19,188
76,474
619.10
19,443
78,405
619.20
19,698
80,362
619.30
19,953
82,345
619.40
20,208
84,353
619.50
20,464
86,386
619.60
20,719
88,445
619.70
20,974
90,530
619.80
21,229
92,640
619.90
21,484
94,776
620.00
21,739
96,937

SAND FILTER-6
......
AFM
_
t + + OF f +
r ++++ter++#r
-.�
W&OP
....... " ...ter. . " ".' 4.'.. + + + + +
.. .. .. ... .. ar. ...... ... ... .. - l++++#+�+ + +++�y
. ....... '. + + + +1
.. .."....
...."..". "
+ + + + +h +"
N—L
... �.; .
'.... '. �.. _ 1 f J

Mt. Pleasant, NC
Sand Filter Calculation
1. Calculate Runoff Coeff, (Rv)
Drainage area to filter, Ad =
Impervious area to filter forebay=
Impervious percentage =
Rv = 0.05 + 0.9(la) _
2. Calculate req'd water quality volume (WQV)
Brighton Park
6
9.94 ac
4.59 ac.
46.19%
0.465695
Storage:
Cum
Elev.
Area
Vol.
Vol
618
12647
0
0
620
16093
28740
28740
622
19943
36036
64776
624
24198
44141
108917
Calculate Depth for WQ Volume:
618
0
619.17
16803
620
28740
Elevation of WQ Volume = 619.17
3. Convert Water Quality Volume, WQv to inches of runoff.
WQv = 1.0(Rv) = 0.47 inches
4. Site Hydrologic Input Parameters:
Cn Pre = 73.0
Cn Post = 83.0
WQV = (Rv/1 x Ad/1 x 43560 sf/1 ac x Rd/1 x ft/12 in)
WQV = 16803 cf (used to size Af)
WQV= 0.3858 ac-ft.
to pond

Table 4.8.3 Results of Hvdrolooic Calculations from HvdroCad
Condition
Q 1- ear
Q 10- r.
Q 25- r
Q 50 yr
Runoff
Pre Dev.
5.62
17.91
23.55
28.71
Post. Dev.
25.25
58.55
72.49
84.89
Routed
0.48
4.05
15.38
30.35
Peak Stage
620.36
622.18
622.56
622.97
Disch. Time
1165 hours
I
1
11' Freeboard
Required
5. First 1/2 inch 0.41 ac-ft 18041.1 cf
Detain 18 hrs 34376 cf Provided
36 hrs 25238 cf
Release Peak-36 hrs 24068 cf Provided
6. Channel Protection Volume: CPv to be held for 24 hours + 12 hours = 36 hours
S = 1000/Cn-10 where Cn = 83.0
S = 2.05 inches
Compute total runoff for the 1-year, 24-hour storm event. Total rainfall depth is
Qd = (P-0.2S)^2/(P+0.8S) 2.9 1-year storm
Qd= 1.37 inches
Watershed Runoff = (Qd)(DA)(1 ft/12") = 1.13 ac-ft. = 1.116 per Hydro -CAD
From HydroCad- Max Release Rate = 0.48 cfs
From HydroCad: Maximum Stage: 620.36
Storage: 34481 cf
Drawdown Time: 165 hours
7. Sedimentation Basin Surface Area
Min As = 0.20 x WQV = As = 3361 sf
8. Sand Filter Bed Surface Area (Af)
1626 sf
Af = (WQV x df)/(k x t x (ha + df) ha = average head
df = 1.5 (depth of filter media)
hmax = 1.17
OK
Calculate Ha = hmax/2 = 0.58 ft
Where df = depth of filter bed (15), k = permeability of sand (3.5), ha = avg depth, t=51 hrs=2.125 days
Af = 1626 sf 237.34 cf/hr = 0.0659284 cfs
hmax = 1.169331942 16803 cf/(As + Af)
Choose As + Af = 4986 sf
Per plan, As = 4303
Af = 3169
Total 7472 OK

9. Sand Filter Drawdown Calculation
Coeff. Of Permeability of filter media = 3.5ft/day = 0.146 ft/hr
Volume of water drained in one hour = 0.146 ft/hr x Af s.f. = 237.3424 cf/hour
Drawdown Time = WQV/Drawdown Rate = 70.80 hrs 2.949905 days
Underdrain Calculations:
78 I.f of underdrain shown; provide 6" perforated pvc pipe with 3/8" perforations spaces 3" o.c. - 4 longitudinal rows
spaced 90 degrees apart.
80 I.f. of pipe
80 I.f. x 4 rows/ft x 4 holes/ft =
50% of perforations =
Capacity of one hole =
1280 holes
640 holes
0.0083 cfs based upon CA(2gh)^0.5
Total Capacity = 5.312 cfs which is 80.6 times the capacity of the sand filter.
Total Capacityof 6" PVC @ 0.50% is 0.40 cfs (0.20 cfs assuming 50% clogged) from Mannings and BMP Manual.
10. Antiflotation Calculation
8 Height of Riser, ft.
6 Area of Riser, s.f.
48 Volume of Riser, c.f.
2995.2 Weight of Water @ 62.4 pcf
3294.72 Weight of water with safety factor of 1.1
82.6 Buoyant Wt. of Concrete = (145-62.4) pcf
1.48 Volume of Concrete Req'd in c.y.
39.89 Volume of Concrete Req'd in c.f.
48 Volume of Concrete in Structure (cf)
-8.11 Volume of Concrete Required (cf)
0.5 ft thick
2.8 Length/Width
(If negative, additional concrete weight not required)

Brighton Park
Mt. Pleasant, NC
1. Develop Stage -Discharge Data for Sand Filter Media.
From 4.8.18 of the BMP Standards Manual:
Q = Af(k)(h+df)/(df)
Latham -Walters Engineering, Inc.
16507-A Northcross Drive
Huntersville, NC 28078
where Af = surface area of filter bed = 1626 sf
df = filter bed depth, ft. = 1.5 ft.
k = coefficient of permeability of filter media (ft/day) _ ft/day
h = average height of water above filter bed (ft) 12, etc.
h
Q
cf/day
Q
cfs
1
9482.856
0.110
2
13276
0.154
3
17069.14
0.198
4
20862.28
0.241
5
24655.43
0.285
6
28448.57
0.329
7
32241.71
0.373
8
36034.85
0.417
9
39828
0.461
10
43621.14
0.505

is
(Predeveloped)
(Post Developed)
Subcat Reach on Link
(BMP6)

2020.17-BM P6
Prepared by {enter your company name here} Page 2
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Area Listing (all nodes)
Area (acres) CN Description (subcats)
8.510 73 Woods, Fair, HSG C (1 S)
1.430 79 Pasture/grassland/range, Fair, HSG C (1S)
9.940 83 RM-2 (C) (2S)
iDrr:1i]

2020.17-BMP6 Type 11 24-hr 1-yr Concord Rainfall=2.90"
Prepared by {enter your company name here} Page 3
HvdroCAD® 8.00 s/n 004317 © 2006 HvdroCAD Software Solutions LLC 6/5/2022
Time span=0.00-200.00 hrs, dt=0.01 hrs, 20001 points
Runoff by SCS TR-20 method, UH=SCS
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment 1S: (Predeveloped) Runoff Area=9.940 ac Runoff Depth=0.85"
Flow Length=598' Tc=37.6 min CN=74 Runoff=5.62 cfs 0.700 of
Subcatchment 2S: (Post Developed) Runoff Area=9.940 ac Runoff Depth=1.37"
Tc=5.0 min CN=83 Runoff=25.25 cfs 1.132 of
Pond 3P: (BMP6) Peak Elev=620.36' Storage=34,692 cf Inflow=25.25 cfs 1.132 of
Primary=0.48 cfs 1.128 of Secondary=0.00 cfs 0.000 of Outflow=0.48 cfs 1.128 of
Total Runoff Area = 19.880 ac Runoff Volume = 1.832 of Average Runoff Depth = 1.11"
100.00% Pervious Area = 19.880 ac 0.00% Impervious Area = 0.000 ac

2020.17-BMP6 Type 11 24-hr 1-yr Concord Rainfall=2.90"
Prepared by {enter your company name here} Page 4
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Subcatchment 1S: (Predeveloped)
BASED ON EXISTING CONDITIONS
Runoff = 5.62 cfs @ 12.37 hrs, Volume= 0.700 af, Depth= 0.85"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Type II 24-hr 1-yr Concord Rainfall=2.90"
Area (ac)
CN
Description
8.510
73
Woods, Fair, HSG C
1.430
79
Pasture/grassland/range, Fair, HSG C
9.940
74
Weighted Average
9.940
Pervious Area
Tc
Length
Slope
Velocity
Capacity Description
(min)
(feet)
(ft/ft)
(ft/sec)
(cfs)
32.8
100
0.0248
0.05
Sheet Flow,
Woods: Dense underbrush n= 0.800 P2= 3.50"
4.8
498
0.1210
1.74
Shallow Concentrated Flow,
Woodland Kv= 5.0 fps

2020.17-BM P6
Type // 24-hr 1-yr Concord Rainfall=2.90"
Prepared by {enter your company name here} Page 5
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Hydrograph for Subcatchment 1S: (Predeveloped)
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
0.00
0.00
0.00
0.00
2.00
0.06
0.00
0.00
4.00
0.14
0.00
0.00
6.00
0.23
0.00
0.00
8.00
0.35
0.00
0.00
10.00
0.52
0.00
0.00
12.00
1.92
0.31
1.17
14.00
2.38
0.54
0.78
16.00
2.55
0.64
0.44
18.00
2.67
0.71
0.33
20.00
2.76
0.76
0.25
22.00
2.83
0.80
0.22
24.00
2.90
0.85
0.20
26.00
2.90
0.85
0.00
28.00
2.90
0.85
0.00
30.00
2.90
0.85
0.00
32.00
2.90
0.85
0.00
34.00
2.90
0.85
0.00
36.00
2.90
0.85
0.00
38.00
2.90
0.85
0.00
40.00
2.90
0.85
0.00
42.00
2.90
0.85
0.00
44.00
2.90
0.85
0.00
46.00
2.90
0.85
0.00
48.00
2.90
0.85
0.00
50.00
2.90
0.85
0.00
52.00
2.90
0.85
0.00
54.00
2.90
0.85
0.00
56.00
2.90
0.85
0.00
58.00
2.90
0.85
0.00
60.00
2.90
0.85
0.00
62.00
2.90
0.85
0.00
64.00
2.90
0.85
0.00
66.00
2.90
0.85
0.00
68.00
2.90
0.85
0.00
70.00
2.90
0.85
0.00
72.00
2.90
0.85
0.00
74.00
2.90
0.85
0.00
76.00
2.90
0.85
0.00
78.00
2.90
0.85
0.00
80.00
2.90
0.85
0.00
82.00
2.90
0.85
0.00
84.00
2.90
0.85
0.00
86.00
2.90
0.85
0.00
88.00
2.90
0.85
0.00
90.00
2.90
0.85
0.00
92.00
2.90
0.85
0.00
94.00
2.90
0.85
0.00
96.00
2.90
0.85
0.00
98.00
2.90
0.85
0.00
100.00
2.90
0.85
0.00
102.00
2.90
0.85
0.00
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
104.00
2.90
0.85
0.00
106.00
2.90
0.85
0.00
108.00
2.90
0.85
0.00
110.00
2.90
0.85
0.00
112.00
2.90
0.85
0.00
114.00
2.90
0.85
0.00
116.00
2.90
0.85
0.00
118.00
2.90
0.85
0.00
120.00
2.90
0.85
0.00
122.00
2.90
0.85
0.00
124.00
2.90
0.85
0.00
126.00
2.90
0.85
0.00
128.00
2.90
0.85
0.00
130.00
2.90
0.85
0.00
132.00
2.90
0.85
0.00
134.00
2.90
0.85
0.00
136.00
2.90
0.85
0.00
138.00
2.90
0.85
0.00
140.00
2.90
0.85
0.00
142.00
2.90
0.85
0.00
144.00
2.90
0.85
0.00
146.00
2.90
0.85
0.00
148.00
2.90
0.85
0.00
150.00
2.90
0.85
0.00
152.00
2.90
0.85
0.00
154.00
2.90
0.85
0.00
156.00
2.90
0.85
0.00
158.00
2.90
0.85
0.00
160.00
2.90
0.85
0.00
162.00
2.90
0.85
0.00
164.00
2.90
0.85
0.00
166.00
2.90
0.85
0.00
168.00
2.90
0.85
0.00
170.00
2.90
0.85
0.00
172.00
2.90
0.85
0.00
174.00
2.90
0.85
0.00
176.00
2.90
0.85
0.00
178.00
2.90
0.85
0.00
180.00
2.90
0.85
0.00
182.00
2.90
0.85
0.00
184.00
2.90
0.85
0.00
186.00
2.90
0.85
0.00
188.00
2.90
0.85
0.00
190.00
2.90
0.85
0.00
192.00
2.90
0.85
0.00
194.00
2.90
0.85
0.00
196.00
2.90
0.85
0.00
198.00
2.90
0.85
0.00
200.00
2.90
0.85
0.00

2020.17-BM P6 Type 11 24-hr 1-yr Concord Rainfall=2.90"
Prepared by {enter your company name here} Page 6
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Subcatchment 2S: (Post Developed)
Runoff = 25.25 cfs @ 11.96 hrs, Volume= 1.132 af, Depth= 1.37"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Type II 24-hr 1-yr Concord Rainfall=2.90"
Area (ac) CN Description
9.940 83 RM-2 (C)
9.940 Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,

2020.17-BM P6
Type // 24-hr 1-yr Concord Rainfall=2.90"
Prepared by {enter your company name here} Page 7
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Hydrograph for Subcatchment 2S: (Post Developed)
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
0.00
0.00
0.00
0.00
2.00
0.06
0.00
0.00
4.00
0.14
0.00
0.00
6.00
0.23
0.00
0.00
8.00
0.35
0.00
0.00
10.00
0.52
0.01
0.11
12.00
1.92
0.64
21.89
14.00
2.38
0.96
0.83
16.00
2.55
1.10
0.52
18.00
2.67
1.19
0.41
20.00
2.76
1.26
0.30
22.00
2.83
1.31
0.28
24.00
2.90
1.37
0.26
26.00
2.90
1.37
0.00
28.00
2.90
1.37
0.00
30.00
2.90
1.37
0.00
32.00
2.90
1.37
0.00
34.00
2.90
1.37
0.00
36.00
2.90
1.37
0.00
38.00
2.90
1.37
0.00
40.00
2.90
1.37
0.00
42.00
2.90
1.37
0.00
44.00
2.90
1.37
0.00
46.00
2.90
1.37
0.00
48.00
2.90
1.37
0.00
50.00
2.90
1.37
0.00
52.00
2.90
1.37
0.00
54.00
2.90
1.37
0.00
56.00
2.90
1.37
0.00
58.00
2.90
1.37
0.00
60.00
2.90
1.37
0.00
62.00
2.90
1.37
0.00
64.00
2.90
1.37
0.00
66.00
2.90
1.37
0.00
68.00
2.90
1.37
0.00
70.00
2.90
1.37
0.00
72.00
2.90
1.37
0.00
74.00
2.90
1.37
0.00
76.00
2.90
1.37
0.00
78.00
2.90
1.37
0.00
80.00
2.90
1.37
0.00
82.00
2.90
1.37
0.00
84.00
2.90
1.37
0.00
86.00
2.90
1.37
0.00
88.00
2.90
1.37
0.00
90.00
2.90
1.37
0.00
92.00
2.90
1.37
0.00
94.00
2.90
1.37
0.00
96.00
2.90
1.37
0.00
98.00
2.90
1.37
0.00
100.00
2.90
1.37
0.00
102.00
2.90
1.37
0.00
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
104.00
2.90
1.37
0.00
106.00
2.90
1.37
0.00
108.00
2.90
1.37
0.00
110.00
2.90
1.37
0.00
112.00
2.90
1.37
0.00
114.00
2.90
1.37
0.00
116.00
2.90
1.37
0.00
118.00
2.90
1.37
0.00
120.00
2.90
1.37
0.00
122.00
2.90
1.37
0.00
124.00
2.90
1.37
0.00
126.00
2.90
1.37
0.00
128.00
2.90
1.37
0.00
130.00
2.90
1.37
0.00
132.00
2.90
1.37
0.00
134.00
2.90
1.37
0.00
136.00
2.90
1.37
0.00
138.00
2.90
1.37
0.00
140.00
2.90
1.37
0.00
142.00
2.90
1.37
0.00
144.00
2.90
1.37
0.00
146.00
2.90
1.37
0.00
148.00
2.90
1.37
0.00
150.00
2.90
1.37
0.00
152.00
2.90
1.37
0.00
154.00
2.90
1.37
0.00
156.00
2.90
1.37
0.00
158.00
2.90
1.37
0.00
160.00
2.90
1.37
0.00
162.00
2.90
1.37
0.00
164.00
2.90
1.37
0.00
166.00
2.90
1.37
0.00
168.00
2.90
1.37
0.00
170.00
2.90
1.37
0.00
172.00
2.90
1.37
0.00
174.00
2.90
1.37
0.00
176.00
2.90
1.37
0.00
178.00
2.90
1.37
0.00
180.00
2.90
1.37
0.00
182.00
2.90
1.37
0.00
184.00
2.90
1.37
0.00
186.00
2.90
1.37
0.00
188.00
2.90
1.37
0.00
190.00
2.90
1.37
0.00
192.00
2.90
1.37
0.00
194.00
2.90
1.37
0.00
196.00
2.90
1.37
0.00
198.00
2.90
1.37
0.00
200.00
2.90
1.37
0.00

2020.17-BMP6 Type 11 24-hr 1-yr Concord Rainfall=2.90"
Prepared by {enter your company name here} Page 8
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Pond 3P: (BMP6)
Inflow Area = 9.940 ac, Inflow Depth = 1.37" for 1-yr Concord event
Inflow =
25.25 cfs @
11.96 hrs,
Volume=
1.132 of
Outflow =
0.48 cfs @
16.62 hrs,
Volume=
1.128 af, Atten= 98%, Lag= 279.2 min
Primary =
0.48 cfs @
16.62 hrs,
Volume=
1.128 of
Secondary =
0.00 cfs @
0.00 hrs,
Volume=
0.000 of
Routing by Stor-Ind method, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Peak Elev= 620.36' @ 16.62 hrs Surf.Area= 16,791 sf Storage= 34,692 cf
Plug -Flow detention time= 2,003.1 min calculated for 1.127 of (100% of inflow)
Center -of -Mass det. time= 2,001.2 min ( 2,834.7 - 833.5 )
Volume Invert Avail.Storage Storage Description
#1 618.00' 108,921 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic -feet) (cubic -feet)
618.00 12,647 0 0
620.00 16,095 28,742 28,742
622.00 19,943 36,038 64,780
624.00 24,198 44,141 108,921
Device Routing Invert Outlet Devices
#1 Primary 596.11' 18.0" x 18.0' long Culvert RCP, square edge headwall, Ke= 0.500
Outlet Invert= 596.00' S= 0.0061 T Cc= 0.900 n= 0.013
#2 Device 1 618.00' Exfiltration
Head (feet) 0.00 1.00 2.00 3.00 4.00 5.00 6.00
Disch. (cfs) 0.000 0.110 0.154 0.198 0.241 0.285 0.329
#3 Device 1 620.00' 6.0" Vert. Orifice/Grate C= 0.600
#4 Device 1 622.00' 2.00' x 3.00' Horiz. Top of Riser Limited to weir flow C= 0.600
#5 Secondary 623.00' 10.0' long x 16.0' breadth Spillway
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Coef. (English) 2.68 2.70 2.70 2.64 2.63 2.64 2.64 2.63
Primary OutFlow Max=0.48 cfs @ 16.62 hrs HW=620.36' (Free Discharge)
L1=Culvert (Passes 0.48 cfs of 41.25 cfs potential flow)
2=Exfltration (Custom Controls 0.17 cfs)
3=Orifice/Grate (Orifice Controls 0.31 cfs @ 2.05 fps)
=Top of Riser ( Controls 0.00 cfs)
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=618.00' (Free Discharge)
5=Spillway ( Controls 0.00 cfs)

2020.17-BM P6
Type // 24-hr 1-yr Concord Rainfall=2.90"
Prepared by {enter your company name here} Page 9
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Hydrograph for Pond 3P: (BMP6)
Time
Inflow
Storage
Elevation
Outflow
Primary
Secondary
(hours)
(cfs)
(cubic -feet)
(feet)
(cfs)
(cfs)
(cfs)
0.00
0.00
0
618.00
0.00
0.00
0.00
5.00
0.00
0
618.00
0.00
0.00
0.00
10.00
0.11
188
618.01
0.00
0.00
0.00
15.00
0.67
34,185
620.33
0.44
0.44
0.00
20.00
0.30
33,889
620.31
0.42
0.42
0.00
25.00
0.00
31,686
620.18
0.26
0.26
0.00
30.00
0.00
28,395
619.98
0.15
0.15
0.00
35.00
0.00
25,708
619.81
0.15
0.15
0.00
40.00
0.00
23,152
619.65
0.14
0.14
0.00
45.00
0.00
20,723
619.49
0.13
0.13
0.00
50.00
0.00
18,418
619.33
0.12
0.12
0.00
55.00
0.00
16,231
619.19
0.12
0.12
0.00
60.00
0.00
14,160
619.05
0.11
0.11
0.00
65.00
0.00
12,234
618.91
0.10
0.10
0.00
70.00
0.00
10,552
618.79
0.09
0.09
0.00
75.00
0.00
9,090
618.69
0.08
0.08
0.00
80.00
0.00
7,824
618.59
0.07
0.07
0.00
85.00
0.00
6,728
618.51
0.06
0.06
0.00
90.00
0.00
5,782
618.44
0.05
0.05
0.00
95.00
0.00
4,965
618.38
0.04
0.04
0.00
100.00
0.00
4,262
618.33
0.04
0.04
0.00
105.00
0.00
3,656
618.28
0.03
0.03
0.00
110.00
0.00
3,135
618.24
0.03
0.03
0.00
115.00
0.00
2,687
618.21
0.02
0.02
0.00
120.00
0.00
2,302
618.18
0.02
0.02
0.00
125.00
0.00
1,972
618.15
0.02
0.02
0.00
130.00
0.00
1,689
618.13
0.01
0.01
0.00
135.00
0.00
1,446
618.11
0.01
0.01
0.00
140.00
0.00
1,238
618.10
0.01
0.01
0.00
145.00
0.00
1,060
618.08
0.01
0.01
0.00
150.00
0.00
907
618.07
0.01
0.01
0.00
155.00
0.00
776
618.06
0.01
0.01
0.00
160.00
0.00
664
618.05
0.01
0.01
0.00
165.00
0.00
568
618.04
0.00
0.00
0.00
170.00
0.00
486
618.04
0.00
0.00
0.00
175.00
0.00
416
618.03
0.00
0.00
0.00
180.00
0.00
356
618.03
0.00
0.00
0.00
185.00
0.00
305
618.02
0.00
0.00
0.00
190.00
0.00
261
618.02
0.00
0.00
0.00
195.00
0.00
223
618.02
0.00
0.00
0.00
200.00
0.00
191
618.02
0.00
0.00
0.00

2020.17-BM P6
Type 11 24-hr 1-yr Concord Rainfall=2.90"
Prepared by {enter your company name here} Page 10
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Stage -Discharge for Pond 3P: (BMP6)
Elevation Discharge Primary Secondary
(feet)
(cfs)
(cfs)
(cfs)
618.00
0.00
0.00
0.00
618.10
0.01
0.01
0.00
618.20
0.02
0.02
0.00
618.30
0.03
0.03
0.00
618.40
0.04
0.04
0.00
618.50
0.06
0.06
0.00
618.60
0.07
0.07
0.00
618.70
0.08
0.08
0.00
618.80
0.09
0.09
0.00
618.90
0.10
0.10
0.00
619.00
0.11
0.11
0.00
619.10
0.11
0.11
0.00
619.20
0.12
0.12
0.00
619.30
0.12
0.12
0.00
619.40
0.13
0.13
0.00
619.50
0.13
0.13
0.00
619.60
0.14
0.14
0.00
619.70
0.14
0.14
0.00
619.80
0.15
0.15
0.00
619.90
0.15
0.15
0.00
620.00
0.15
0.15
0.00
620.10
0.19
0.19
0.00
620.20
0.27
0.27
0.00
620.30
0.40
0.40
0.00
620.40
0.53
0.53
0.00
620.50
0.65
0.65
0.00
620.60
0.74
0.74
0.00
620.70
0.82
0.82
0.00
620.80
0.89
0.89
0.00
620.90
0.96
0.96
0.00
621.00
1.02
1.02
0.00
621.10
1.07
1.07
0.00
621.20
1.13
1.13
0.00
621.30
1.18
1.18
0.00
621.40
1.23
1.23
0.00
621.50
1.28
1.28
0.00
621.60
1.32
1.32
0.00
621.70
1.37
1.37
0.00
621.80
1.41
1.41
0.00
621.90
1.45
1.45
0.00
622.00
1.49
1.49
0.00
622.10
2.57
2.57
0.00
622.20
4.49
4.49
0.00
622.30
6.98
6.98
0.00
622.40
9.92
9.92
0.00
622.50
13.24
13.24
0.00
622.60
16.91
16.91
0.00
622.70
20.90
20.90
0.00
622.80
25.18
25.18
0.00
622.90
29.23
29.23
0.00
623.00
30.74
30.74
0.00
623.10
33.03
32.19
0.85
Elevation Discharge Primary Secondary
(feet)
(cfs)
(cfs)
(cfs)
623.20
35.96
33.56
2.40
623.30
39.31
34.89
4.42
623.40
42.99
36.16
6.83
623.50
46.94
37.39
9.55
623.60
51.13
38.58
12.55
623.70
55.38
39.74
15.64
623.80
59.75
40.86
18.89
623.90
64.45
41.95
22.50
624.00
69.32
43.02
26.30

2020.17-BM P6
Type 11 24-hr 1-yr Concord Rainfall=2.90"
Prepared by {enter your company name here} Page 11
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Stage -Area -Storage for Pond 3P: (BMP6)
Elevation
Surface
Storage
(feet)
(sq-ft)
(cubic -feet)
618.00
12,647
0
618.10
12,819
1,273
618.20
12,992
2,564
618.30
13,164
3,872
618.40
13,337
5,197
618.50
13,509
6,539
618.60
13,681
7,899
618.70
13,854
9,275
618.80
14,026
10,669
618.90
14,199
12,081
619.00
14,371
13,509
619.10
14,543
14,955
619.20
14,716
16,418
619.30
14,888
17,898
619.40
15,061
19,395
619.50
15,233
20,910
619.60
15,405
22,442
619.70
15,578
23,991
619.80
15,750
25,557
619.90
15,923
27,141
620.00
16,095
28,742
620.10
16,287
30,361
620.20
16,480
31,999
620.30
16,672
33,657
620.40
16,865
35,334
620.50
17,057
37,030
620.60
17,249
38,745
620.70
17,442
40,480
620.80
17,634
42,234
620.90
17,827
44,007
621.00
18,019
45,799
621.10
18,211
47,611
621.20
18,404
49,441
621.30
18,596
51,291
621.40
18,789
53,161
621.50
18,981
55,049
621.60
19,173
56,957
621.70
19,366
58,884
621.80
19,558
60,830
621.90
19,751
62,795
622.00
19,943
64,780
622.10
20,156
66,785
622.20
20,369
68,811
622.30
20,581
70,859
622.40
20,794
72,927
622.50
21,007
75,017
622.60
21,220
77,129
622.70
21,432
79,261
622.80
21,645
81,415
622.90
21,858
83,590
623.00
22,071
85,787
623.10
22,283
88,004
Elevation
Surface
Storage
(feet)
(sq-ft)
(cubic -feet)
623.20
22,496
90,243
623.30
22,709
92,504
623.40
22,921
94,785
623.50
23,134
97,088
623.60
23,347
99,412
623.70
23,560
101,757
623.80
23,772
104,124
623.90
23,985
106,512
624.00
24,198
108,921

2020.17-BM P6 Type 11 24-hr 10-yr Concord Rainfall=5.10"
Prepared by {enter your company name here} Page 12
HvdroCAD® 8.00 s/n 004317 © 2006 HvdroCAD Software Solutions LLC 6/5/2022
Time span=0.00-200.00 hrs, dt=0.01 hrs, 20001 points
Runoff by SCS TR-20 method, UH=SCS
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment 1S: (Predeveloped) Runoff Area=9.940 ac Runoff Depth=2.44"
Flow Length=598' Tc=37.6 min CN=74 Runoff=17.91 cfs 2.025 of
Subcatchment 2S: (Post Developed) Runoff Area=9.940 ac Runoff Depth=3.26"
Tc=5.0 min CN=83 Runoff=58.55 cfs 2.704 of
Pond 3P: (BMP6) Peak Elev=622.18' Storage=68,370 cf Inflow=58.55 cfs 2.704 of
Primary=4.05 cfs 2.699 of Secondary=0.00 cfs 0.000 of Outflow=4.05 cfs 2.699 of
Total Runoff Area = 19.880 ac Runoff Volume = 4.729 of Average Runoff Depth = 2.85"
100.00% Pervious Area = 19.880 ac 0.00% Impervious Area = 0.000 ac

2020.17-BM P6 Type 11 24-hr 10-yr Concord Rainfall=5.10"
Prepared by {enter your company name here} Page 13
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Subcatchment 1S: (Predeveloped)
BASED ON EXISTING CONDITIONS
Runoff = 17.91 cfs @ 12.33 hrs, Volume= 2.025 af, Depth= 2.44"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Type II 24-hr 10-yr Concord Rainfall=5.10"
Area (ac)
CN
Description
8.510
73
Woods, Fair, HSG C
1.430
79
Pasture/grassland/range, Fair, HSG C
9.940
74
Weighted Average
9.940
Pervious Area
Tc
Length
Slope
Velocity
Capacity Description
(min)
(feet)
(ft/ft)
(ft/sec)
(cfs)
32.8
100
0.0248
0.05
Sheet Flow,
Woods: Dense underbrush n= 0.800 P2= 3.50"
4.8
498
0.1210
1.74
Shallow Concentrated Flow,
Woodland Kv= 5.0 fps

2020.17-BM P6
Type 11 24-hr 10-yr Concord Rainfall=5.10"
Prepared by {enter your company name here} Page 14
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Hydrograph for Subcatchment 1S: (Predeveloped)
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
0.00
0.00
0.00
0.00
2.00
0.11
0.00
0.00
4.00
0.24
0.00
0.00
6.00
0.41
0.00
0.00
8.00
0.61
0.00
0.00
10.00
0.92
0.01
0.11
12.00
3.38
1.16
5.58
14.00
4.18
1.73
1.91
16.00
4.49
1.96
1.06
18.00
4.70
2.13
0.77
20.00
4.86
2.25
0.58
22.00
4.98
2.35
0.50
24.00
5.10
2.44
0.46
26.00
5.10
2.44
0.00
28.00
5.10
2.44
0.00
30.00
5.10
2.44
0.00
32.00
5.10
2.44
0.00
34.00
5.10
2.44
0.00
36.00
5.10
2.44
0.00
38.00
5.10
2.44
0.00
40.00
5.10
2.44
0.00
42.00
5.10
2.44
0.00
44.00
5.10
2.44
0.00
46.00
5.10
2.44
0.00
48.00
5.10
2.44
0.00
50.00
5.10
2.44
0.00
52.00
5.10
2.44
0.00
54.00
5.10
2.44
0.00
56.00
5.10
2.44
0.00
58.00
5.10
2.44
0.00
60.00
5.10
2.44
0.00
62.00
5.10
2.44
0.00
64.00
5.10
2.44
0.00
66.00
5.10
2.44
0.00
68.00
5.10
2.44
0.00
70.00
5.10
2.44
0.00
72.00
5.10
2.44
0.00
74.00
5.10
2.44
0.00
76.00
5.10
2.44
0.00
78.00
5.10
2.44
0.00
80.00
5.10
2.44
0.00
82.00
5.10
2.44
0.00
84.00
5.10
2.44
0.00
86.00
5.10
2.44
0.00
88.00
5.10
2.44
0.00
90.00
5.10
2.44
0.00
92.00
5.10
2.44
0.00
94.00
5.10
2.44
0.00
96.00
5.10
2.44
0.00
98.00
5.10
2.44
0.00
100.00
5.10
2.44
0.00
102.00
5.10
2.44
0.00
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
104.00
5.10
2.44
0.00
106.00
5.10
2.44
0.00
108.00
5.10
2.44
0.00
110.00
5.10
2.44
0.00
112.00
5.10
2.44
0.00
114.00
5.10
2.44
0.00
116.00
5.10
2.44
0.00
118.00
5.10
2.44
0.00
120.00
5.10
2.44
0.00
122.00
5.10
2.44
0.00
124.00
5.10
2.44
0.00
126.00
5.10
2.44
0.00
128.00
5.10
2.44
0.00
130.00
5.10
2.44
0.00
132.00
5.10
2.44
0.00
134.00
5.10
2.44
0.00
136.00
5.10
2.44
0.00
138.00
5.10
2.44
0.00
140.00
5.10
2.44
0.00
142.00
5.10
2.44
0.00
144.00
5.10
2.44
0.00
146.00
5.10
2.44
0.00
148.00
5.10
2.44
0.00
150.00
5.10
2.44
0.00
152.00
5.10
2.44
0.00
154.00
5.10
2.44
0.00
156.00
5.10
2.44
0.00
158.00
5.10
2.44
0.00
160.00
5.10
2.44
0.00
162.00
5.10
2.44
0.00
164.00
5.10
2.44
0.00
166.00
5.10
2.44
0.00
168.00
5.10
2.44
0.00
170.00
5.10
2.44
0.00
172.00
5.10
2.44
0.00
174.00
5.10
2.44
0.00
176.00
5.10
2.44
0.00
178.00
5.10
2.44
0.00
180.00
5.10
2.44
0.00
182.00
5.10
2.44
0.00
184.00
5.10
2.44
0.00
186.00
5.10
2.44
0.00
188.00
5.10
2.44
0.00
190.00
5.10
2.44
0.00
192.00
5.10
2.44
0.00
194.00
5.10
2.44
0.00
196.00
5.10
2.44
0.00
198.00
5.10
2.44
0.00
200.00
5.10
2.44
0.00

2020.17-BM P6
Type 11 24-hr 10-yr Concord Rainfall=5.10"
Prepared by {enter your company name here} Page 15
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Subcatchment 2S: (Post Developed)
Runoff = 58.55 cfs @ 11.96 hrs, Volume= 2.704 af, Depth= 3.26"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Type II 24-hr 10-yr Concord Rainfall=5.10"
Area (ac) CN Description
9.940 83 RM-2 (C)
9.940 Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,

2020.17-BM P6
Type 11 24-hr 10-yr Concord Rainfall=5.10"
Prepared by {enter your company name here} Page 16
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Hydrograph for Subcatchment 2S: (Post Developed)
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
0.00
0.00
0.00
0.00
2.00
0.11
0.00
0.00
4.00
0.24
0.00
0.00
6.00
0.41
0.00
0.00
8.00
0.61
0.02
0.18
10.00
0.92
0.10
0.70
12.00
3.38
1.76
49.61
14.00
4.18
2.44
1.72
16.00
4.49
2.71
1.07
18.00
4.70
2.90
0.83
20.00
4.86
3.04
0.61
22.00
4.98
3.16
0.56
24.00
5.10
3.26
0.51
26.00
5.10
3.26
0.00
28.00
5.10
3.26
0.00
30.00
5.10
3.26
0.00
32.00
5.10
3.26
0.00
34.00
5.10
3.26
0.00
36.00
5.10
3.26
0.00
38.00
5.10
3.26
0.00
40.00
5.10
3.26
0.00
42.00
5.10
3.26
0.00
44.00
5.10
3.26
0.00
46.00
5.10
3.26
0.00
48.00
5.10
3.26
0.00
50.00
5.10
3.26
0.00
52.00
5.10
3.26
0.00
54.00
5.10
3.26
0.00
56.00
5.10
3.26
0.00
58.00
5.10
3.26
0.00
60.00
5.10
3.26
0.00
62.00
5.10
3.26
0.00
64.00
5.10
3.26
0.00
66.00
5.10
3.26
0.00
68.00
5.10
3.26
0.00
70.00
5.10
3.26
0.00
72.00
5.10
3.26
0.00
74.00
5.10
3.26
0.00
76.00
5.10
3.26
0.00
78.00
5.10
3.26
0.00
80.00
5.10
3.26
0.00
82.00
5.10
3.26
0.00
84.00
5.10
3.26
0.00
86.00
5.10
3.26
0.00
88.00
5.10
3.26
0.00
90.00
5.10
3.26
0.00
92.00
5.10
3.26
0.00
94.00
5.10
3.26
0.00
96.00
5.10
3.26
0.00
98.00
5.10
3.26
0.00
100.00
5.10
3.26
0.00
102.00
5.10
3.26
0.00
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
104.00
5.10
3.26
0.00
106.00
5.10
3.26
0.00
108.00
5.10
3.26
0.00
110.00
5.10
3.26
0.00
112.00
5.10
3.26
0.00
114.00
5.10
3.26
0.00
116.00
5.10
3.26
0.00
118.00
5.10
3.26
0.00
120.00
5.10
3.26
0.00
122.00
5.10
3.26
0.00
124.00
5.10
3.26
0.00
126.00
5.10
3.26
0.00
128.00
5.10
3.26
0.00
130.00
5.10
3.26
0.00
132.00
5.10
3.26
0.00
134.00
5.10
3.26
0.00
136.00
5.10
3.26
0.00
138.00
5.10
3.26
0.00
140.00
5.10
3.26
0.00
142.00
5.10
3.26
0.00
144.00
5.10
3.26
0.00
146.00
5.10
3.26
0.00
148.00
5.10
3.26
0.00
150.00
5.10
3.26
0.00
152.00
5.10
3.26
0.00
154.00
5.10
3.26
0.00
156.00
5.10
3.26
0.00
158.00
5.10
3.26
0.00
160.00
5.10
3.26
0.00
162.00
5.10
3.26
0.00
164.00
5.10
3.26
0.00
166.00
5.10
3.26
0.00
168.00
5.10
3.26
0.00
170.00
5.10
3.26
0.00
172.00
5.10
3.26
0.00
174.00
5.10
3.26
0.00
176.00
5.10
3.26
0.00
178.00
5.10
3.26
0.00
180.00
5.10
3.26
0.00
182.00
5.10
3.26
0.00
184.00
5.10
3.26
0.00
186.00
5.10
3.26
0.00
188.00
5.10
3.26
0.00
190.00
5.10
3.26
0.00
192.00
5.10
3.26
0.00
194.00
5.10
3.26
0.00
196.00
5.10
3.26
0.00
198.00
5.10
3.26
0.00
200.00
5.10
3.26
0.00

2020.17-BM P6 Type 11 24-hr 10-yr Concord Rainfall=5.10"
Prepared by {enter your company name here} Page 17
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Pond 3P: (BMP6)
Inflow Area = 9.940 ac, Inflow Depth = 3.26" for 10-yr Concord event
Inflow =
58.55 cfs @
11.96 hrs,
Volume=
2.704 of
Outflow =
4.05 cfs @
12.56 hrs,
Volume=
2.699 af, Atten= 93%, Lag= 35.8 min
Primary =
4.05 cfs @
12.56 hrs,
Volume=
2.699 of
Secondary =
0.00 cfs @
0.00 hrs,
Volume=
0.000 of
Routing by Stor-Ind method, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Peak Elev= 622.18' @ 12.56 hrs Surf.Area= 20,322 sf Storage= 68,370 cf
Plug -Flow detention time= 1,117.3 min calculated for 2.699 of (100% of inflow)
Center -of -Mass det. time= 1,116.1 min ( 1,924.7 - 808.6 )
Volume Invert Avail.Storage Storage Description
#1 618.00' 108,921 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic -feet) (cubic -feet)
618.00 12,647 0 0
620.00 16,095 28,742 28,742
622.00 19,943 36,038 64,780
624.00 24,198 44,141 108,921
Device Routing Invert Outlet Devices
#1 Primary 596.11' 18.0" x 18.0' long Culvert RCP, square edge headwall, Ke= 0.500
Outlet Invert= 596.00' S= 0.0061 T Cc= 0.900 n= 0.013
#2 Device 1 618.00' Exfiltration
Head (feet) 0.00 1.00 2.00 3.00 4.00 5.00 6.00
Disch. (cfs) 0.000 0.110 0.154 0.198 0.241 0.285 0.329
#3 Device 1 620.00' 6.0" Vert. Orifice/Grate C= 0.600
#4 Device 1 622.00' 2.00' x 3.00' Horiz. Top of Riser Limited to weir flow C= 0.600
#5 Secondary 623.00' 10.0' long x 16.0' breadth Spillway
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Coef. (English) 2.68 2.70 2.70 2.64 2.63 2.64 2.64 2.63
Primary OutFlow Max=4.02 cfs @ 12.56 hrs HW=622.18' (Free Discharge)
L1=Culvert (Passes 4.02 cfs of 42.81 cfs potential flow)
2=Exfltration (Custom Controls 0.25 cfs)
3=Orifice/Grate (Orifice Controls 1.31 cfs @ 6.69 fps)
=Top of Riser (Weir Controls 2.46 cfs @ 1.38 fps)
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=618.00' (Free Discharge)
5=Spillway ( Controls 0.00 cfs)

2020.17-BM P6
Type 11 24-hr 10-yr Concord Rainfall=5.10"
Prepared by {enter your company name here} Page 18
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Hydrograph for Pond 3P: (BMP6)
Time
Inflow
Storage
Elevation
Outflow
Primary
Secondary
(hours)
(cfs)
(cubic -feet)
(feet)
(cfs)
(cfs)
(cfs)
0.00
0.00
0
618.00
0.00
0.00
0.00
5.00
0.00
0
618.00
0.00
0.00
0.00
10.00
0.70
3,397
618.26
0.03
0.03
0.00
15.00
1.38
65,134
622.02
1.58
1.58
0.00
20.00
0.61
55,960
621.55
1.30
1.30
0.00
25.00
0.00
43,561
620.87
0.94
0.94
0.00
30.00
0.00
32,496
620.23
0.31
0.31
0.00
35.00
0.00
28,839
620.01
0.16
0.16
0.00
40.00
0.00
26,129
619.84
0.15
0.15
0.00
45.00
0.00
23,553
619.67
0.14
0.14
0.00
50.00
0.00
21,104
619.51
0.13
0.13
0.00
55.00
0.00
18,779
619.36
0.13
0.13
0.00
60.00
0.00
16,574
619.21
0.12
0.12
0.00
65.00
0.00
14,484
619.07
0.11
0.11
0.00
70.00
0.00
12,526
618.93
0.10
0.10
0.00
75.00
0.00
10,805
618.81
0.09
0.09
0.00
80.00
0.00
9,311
618.70
0.08
0.08
0.00
85.00
0.00
8,015
618.61
0.07
0.07
0.00
90.00
0.00
6,893
618.53
0.06
0.06
0.00
95.00
0.00
5,924
618.45
0.05
0.05
0.00
100.00
0.00
5,088
618.39
0.04
0.04
0.00
105.00
0.00
4,367
618.34
0.04
0.04
0.00
110.00
0.00
3,747
618.29
0.03
0.03
0.00
115.00
0.00
3,213
618.25
0.03
0.03
0.00
120.00
0.00
2,754
618.21
0.02
0.02
0.00
125.00
0.00
2,360
618.18
0.02
0.02
0.00
130.00
0.00
2,022
618.16
0.02
0.02
0.00
135.00
0.00
1,731
618.14
0.01
0.01
0.00
140.00
0.00
1,483
618.12
0.01
0.01
0.00
145.00
0.00
1,269
618.10
0.01
0.01
0.00
150.00
0.00
1,086
618.09
0.01
0.01
0.00
155.00
0.00
930
618.07
0.01
0.01
0.00
160.00
0.00
796
618.06
0.01
0.01
0.00
165.00
0.00
681
618.05
0.01
0.01
0.00
170.00
0.00
583
618.05
0.01
0.01
0.00
175.00
0.00
498
618.04
0.00
0.00
0.00
180.00
0.00
427
618.03
0.00
0.00
0.00
185.00
0.00
365
618.03
0.00
0.00
0.00
190.00
0.00
312
618.02
0.00
0.00
0.00
195.00
0.00
267
618.02
0.00
0.00
0.00
200.00
0.00
229
618.02
0.00
0.00
0.00

2020.17-BM P6
Type 11 24-hr 10-yr Concord Rainfall=5.10"
Prepared by {enter your company name here} Page 19
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Stage -Discharge for Pond 3P: (BMP6)
Elevation Discharge Primary Secondary
(feet)
(cfs)
(cfs)
(cfs)
618.00
0.00
0.00
0.00
618.10
0.01
0.01
0.00
618.20
0.02
0.02
0.00
618.30
0.03
0.03
0.00
618.40
0.04
0.04
0.00
618.50
0.06
0.06
0.00
618.60
0.07
0.07
0.00
618.70
0.08
0.08
0.00
618.80
0.09
0.09
0.00
618.90
0.10
0.10
0.00
619.00
0.11
0.11
0.00
619.10
0.11
0.11
0.00
619.20
0.12
0.12
0.00
619.30
0.12
0.12
0.00
619.40
0.13
0.13
0.00
619.50
0.13
0.13
0.00
619.60
0.14
0.14
0.00
619.70
0.14
0.14
0.00
619.80
0.15
0.15
0.00
619.90
0.15
0.15
0.00
620.00
0.15
0.15
0.00
620.10
0.19
0.19
0.00
620.20
0.27
0.27
0.00
620.30
0.40
0.40
0.00
620.40
0.53
0.53
0.00
620.50
0.65
0.65
0.00
620.60
0.74
0.74
0.00
620.70
0.82
0.82
0.00
620.80
0.89
0.89
0.00
620.90
0.96
0.96
0.00
621.00
1.02
1.02
0.00
621.10
1.07
1.07
0.00
621.20
1.13
1.13
0.00
621.30
1.18
1.18
0.00
621.40
1.23
1.23
0.00
621.50
1.28
1.28
0.00
621.60
1.32
1.32
0.00
621.70
1.37
1.37
0.00
621.80
1.41
1.41
0.00
621.90
1.45
1.45
0.00
622.00
1.49
1.49
0.00
622.10
2.57
2.57
0.00
622.20
4.49
4.49
0.00
622.30
6.98
6.98
0.00
622.40
9.92
9.92
0.00
622.50
13.24
13.24
0.00
622.60
16.91
16.91
0.00
622.70
20.90
20.90
0.00
622.80
25.18
25.18
0.00
622.90
29.23
29.23
0.00
623.00
30.74
30.74
0.00
623.10
33.03
32.19
0.85
Elevation Discharge Primary Secondary
(feet)
(cfs)
(cfs)
(cfs)
623.20
35.96
33.56
2.40
623.30
39.31
34.89
4.42
623.40
42.99
36.16
6.83
623.50
46.94
37.39
9.55
623.60
51.13
38.58
12.55
623.70
55.38
39.74
15.64
623.80
59.75
40.86
18.89
623.90
64.45
41.95
22.50
624.00
69.32
43.02
26.30

2020.17-BM P6
Type // 24-hr 10-yr Concord Rainfall=5.10"
Prepared by {enter your company name here} Page 20
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Stage -Area -Storage for Pond 3P: (BMP6)
Elevation
Surface
Storage
(feet)
(sq-ft)
(cubic -feet)
618.00
12,647
0
618.10
12,819
1,273
618.20
12,992
2,564
618.30
13,164
3,872
618.40
13,337
5,197
618.50
13,509
6,539
618.60
13,681
7,899
618.70
13,854
9,275
618.80
14,026
10,669
618.90
14,199
12,081
619.00
14,371
13,509
619.10
14,543
14,955
619.20
14,716
16,418
619.30
14,888
17,898
619.40
15,061
19,395
619.50
15,233
20,910
619.60
15,405
22,442
619.70
15,578
23,991
619.80
15,750
25,557
619.90
15,923
27,141
620.00
16,095
28,742
620.10
16,287
30,361
620.20
16,480
31,999
620.30
16,672
33,657
620.40
16,865
35,334
620.50
17,057
37,030
620.60
17,249
38,745
620.70
17,442
40,480
620.80
17,634
42,234
620.90
17,827
44,007
621.00
18,019
45,799
621.10
18,211
47,611
621.20
18,404
49,441
621.30
18,596
51,291
621.40
18,789
53,161
621.50
18,981
55,049
621.60
19,173
56,957
621.70
19,366
58,884
621.80
19,558
60,830
621.90
19,751
62,795
622.00
19,943
64,780
622.10
20,156
66,785
622.20
20,369
68,811
622.30
20,581
70,859
622.40
20,794
72,927
622.50
21,007
75,017
622.60
21,220
77,129
622.70
21,432
79,261
622.80
21,645
81,415
622.90
21,858
83,590
623.00
22,071
85,787
623.10
22,283
88,004
Elevation
Surface
Storage
(feet)
(sq-ft)
(cubic -feet)
623.20
22,496
90,243
623.30
22,709
92,504
623.40
22,921
94,785
623.50
23,134
97,088
623.60
23,347
99,412
623.70
23,560
101,757
623.80
23,772
104,124
623.90
23,985
106,512
624.00
24,198
108,921

2020.17-BM P6 Type/1 24-hr 25-yr Concord Rainfall=6.00"
Prepared by {enter your company name here} Page 21
HvdroCAD® 8.00 s/n 004317 © 2006 HvdroCAD Software Solutions LLC 6/5/2022
Time span=0.00-200.00 hrs, dt=0.01 hrs, 20001 points
Runoff by SCS TR-20 method, UH=SCS
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment 1S: (Predeveloped) Runoff Area=9.940 ac Runoff Depth=3.18"
Flow Length=598' Tc=37.6 min CN=74 Runoff=23.55 cfs 2.638 of
Subcatchment 2S: (Post Developed) Runoff Area=9.940 ac Runoff Depth=4.09"
Tc=5.0 min CN=83 Runoff=72.49 cfs 3.389 of
Pond 3P: (BMP6) Peak Elev=622.56' Storage=76,260 cf Inflow=72.49 cfs 3.389 of
Primary=15.37 cfs 3.384 of Secondary=0.00 cfs 0.000 of Outflow=15.37 cfs 3.384 of
Total Runoff Area = 19.880 ac Runoff Volume = 6.027 of Average Runoff Depth = 3.64"
100.00% Pervious Area = 19.880 ac 0.00% Impervious Area = 0.000 ac

2020.17-BM P6 Type/1 24-hr 25-yr Concord Rainfall=6.00"
Prepared by {enter your company name here} Page 22
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Subcatchment 1S: (Predeveloped)
BASED ON EXISTING CONDITIONS
Runoff = 23.55 cfs @ 12.33 hrs, Volume= 2.638 af, Depth= 3.18"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Type II 24-hr 25-yr Concord Rainfall=6.00"
Area (ac)
CN
Description
8.510
73
Woods, Fair, HSG C
1.430
79
Pasture/grassland/range, Fair, HSG C
9.940
74
Weighted Average
9.940
Pervious Area
Tc
Length
Slope
Velocity
Capacity Description
(min)
(feet)
(ft/ft)
(ft/sec)
(cfs)
32.8
100
0.0248
0.05
Sheet Flow,
Woods: Dense underbrush n= 0.800 P2= 3.50"
4.8
498
0.1210
1.74
Shallow Concentrated Flow,
Woodland Kv= 5.0 fps

2020.17-BM P6
Type // 24-hr 25-yr Concord Rainfall=6.00"
Prepared by {enter your company name here} Page 23
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Hydrograph for Subcatchment 1S: (Predeveloped)
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
0.00
0.00
0.00
0.00
2.00
0.13
0.00
0.00
4.00
0.29
0.00
0.00
6.00
0.48
0.00
0.00
8.00
0.72
0.00
0.00
10.00
1.09
0.04
0.26
12.00
3.98
1.58
7.74
14.00
4.92
2.30
2.40
16.00
5.28
2.59
1.31
18.00
5.53
2.79
0.96
20.00
5.71
2.94
0.72
22.00
5.86
3.07
0.62
24.00
6.00
3.18
0.57
26.00
6.00
3.18
0.00
28.00
6.00
3.18
0.00
30.00
6.00
3.18
0.00
32.00
6.00
3.18
0.00
34.00
6.00
3.18
0.00
36.00
6.00
3.18
0.00
38.00
6.00
3.18
0.00
40.00
6.00
3.18
0.00
42.00
6.00
3.18
0.00
44.00
6.00
3.18
0.00
46.00
6.00
3.18
0.00
48.00
6.00
3.18
0.00
50.00
6.00
3.18
0.00
52.00
6.00
3.18
0.00
54.00
6.00
3.18
0.00
56.00
6.00
3.18
0.00
58.00
6.00
3.18
0.00
60.00
6.00
3.18
0.00
62.00
6.00
3.18
0.00
64.00
6.00
3.18
0.00
66.00
6.00
3.18
0.00
68.00
6.00
3.18
0.00
70.00
6.00
3.18
0.00
72.00
6.00
3.18
0.00
74.00
6.00
3.18
0.00
76.00
6.00
3.18
0.00
78.00
6.00
3.18
0.00
80.00
6.00
3.18
0.00
82.00
6.00
3.18
0.00
84.00
6.00
3.18
0.00
86.00
6.00
3.18
0.00
88.00
6.00
3.18
0.00
90.00
6.00
3.18
0.00
92.00
6.00
3.18
0.00
94.00
6.00
3.18
0.00
96.00
6.00
3.18
0.00
98.00
6.00
3.18
0.00
100.00
6.00
3.18
0.00
102.00
6.00
3.18
0.00
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
104.00
6.00
3.18
0.00
106.00
6.00
3.18
0.00
108.00
6.00
3.18
0.00
110.00
6.00
3.18
0.00
112.00
6.00
3.18
0.00
114.00
6.00
3.18
0.00
116.00
6.00
3.18
0.00
118.00
6.00
3.18
0.00
120.00
6.00
3.18
0.00
122.00
6.00
3.18
0.00
124.00
6.00
3.18
0.00
126.00
6.00
3.18
0.00
128.00
6.00
3.18
0.00
130.00
6.00
3.18
0.00
132.00
6.00
3.18
0.00
134.00
6.00
3.18
0.00
136.00
6.00
3.18
0.00
138.00
6.00
3.18
0.00
140.00
6.00
3.18
0.00
142.00
6.00
3.18
0.00
144.00
6.00
3.18
0.00
146.00
6.00
3.18
0.00
148.00
6.00
3.18
0.00
150.00
6.00
3.18
0.00
152.00
6.00
3.18
0.00
154.00
6.00
3.18
0.00
156.00
6.00
3.18
0.00
158.00
6.00
3.18
0.00
160.00
6.00
3.18
0.00
162.00
6.00
3.18
0.00
164.00
6.00
3.18
0.00
166.00
6.00
3.18
0.00
168.00
6.00
3.18
0.00
170.00
6.00
3.18
0.00
172.00
6.00
3.18
0.00
174.00
6.00
3.18
0.00
176.00
6.00
3.18
0.00
178.00
6.00
3.18
0.00
180.00
6.00
3.18
0.00
182.00
6.00
3.18
0.00
184.00
6.00
3.18
0.00
186.00
6.00
3.18
0.00
188.00
6.00
3.18
0.00
190.00
6.00
3.18
0.00
192.00
6.00
3.18
0.00
194.00
6.00
3.18
0.00
196.00
6.00
3.18
0.00
198.00
6.00
3.18
0.00
200.00
6.00
3.18
0.00

2020.17-BM P6
Type/1 24-hr 25-yr Concord Rainfall=6.00"
Prepared by {enter your company name here} Page 24
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Subcatchment 2S: (Post Developed)
Runoff = 72.49 cfs @ 11.96 hrs, Volume= 3.389 af, Depth= 4.09"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Type II 24-hr 25-yr Concord Rainfall=6.00"
Area (ac) CN Description
9.940 83 RM-2 (C)
9.940 Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,

2020.17-BM P6
Type // 24-hr 25-yr Concord Rainfall=6.00"
Prepared by {enter your company name here} Page 25
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Hydrograph for Subcatchment 2S: (Post Developed)
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
0.00
0.00
0.00
0.00
2.00
0.13
0.00
0.00
4.00
0.29
0.00
0.00
6.00
0.48
0.00
0.06
8.00
0.72
0.04
0.31
10.00
1.09
0.17
1.00
12.00
3.98
2.27
61.13
14.00
4.92
3.10
2.09
16.00
5.28
3.43
1.29
18.00
5.53
3.65
1.00
20.00
5.71
3.82
0.73
22.00
5.86
3.96
0.67
24.00
6.00
4.09
0.62
26.00
6.00
4.09
0.00
28.00
6.00
4.09
0.00
30.00
6.00
4.09
0.00
32.00
6.00
4.09
0.00
34.00
6.00
4.09
0.00
36.00
6.00
4.09
0.00
38.00
6.00
4.09
0.00
40.00
6.00
4.09
0.00
42.00
6.00
4.09
0.00
44.00
6.00
4.09
0.00
46.00
6.00
4.09
0.00
48.00
6.00
4.09
0.00
50.00
6.00
4.09
0.00
52.00
6.00
4.09
0.00
54.00
6.00
4.09
0.00
56.00
6.00
4.09
0.00
58.00
6.00
4.09
0.00
60.00
6.00
4.09
0.00
62.00
6.00
4.09
0.00
64.00
6.00
4.09
0.00
66.00
6.00
4.09
0.00
68.00
6.00
4.09
0.00
70.00
6.00
4.09
0.00
72.00
6.00
4.09
0.00
74.00
6.00
4.09
0.00
76.00
6.00
4.09
0.00
78.00
6.00
4.09
0.00
80.00
6.00
4.09
0.00
82.00
6.00
4.09
0.00
84.00
6.00
4.09
0.00
86.00
6.00
4.09
0.00
88.00
6.00
4.09
0.00
90.00
6.00
4.09
0.00
92.00
6.00
4.09
0.00
94.00
6.00
4.09
0.00
96.00
6.00
4.09
0.00
98.00
6.00
4.09
0.00
100.00
6.00
4.09
0.00
102.00
6.00
4.09
0.00
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
104.00
6.00
4.09
0.00
106.00
6.00
4.09
0.00
108.00
6.00
4.09
0.00
110.00
6.00
4.09
0.00
112.00
6.00
4.09
0.00
114.00
6.00
4.09
0.00
116.00
6.00
4.09
0.00
118.00
6.00
4.09
0.00
120.00
6.00
4.09
0.00
122.00
6.00
4.09
0.00
124.00
6.00
4.09
0.00
126.00
6.00
4.09
0.00
128.00
6.00
4.09
0.00
130.00
6.00
4.09
0.00
132.00
6.00
4.09
0.00
134.00
6.00
4.09
0.00
136.00
6.00
4.09
0.00
138.00
6.00
4.09
0.00
140.00
6.00
4.09
0.00
142.00
6.00
4.09
0.00
144.00
6.00
4.09
0.00
146.00
6.00
4.09
0.00
148.00
6.00
4.09
0.00
150.00
6.00
4.09
0.00
152.00
6.00
4.09
0.00
154.00
6.00
4.09
0.00
156.00
6.00
4.09
0.00
158.00
6.00
4.09
0.00
160.00
6.00
4.09
0.00
162.00
6.00
4.09
0.00
164.00
6.00
4.09
0.00
166.00
6.00
4.09
0.00
168.00
6.00
4.09
0.00
170.00
6.00
4.09
0.00
172.00
6.00
4.09
0.00
174.00
6.00
4.09
0.00
176.00
6.00
4.09
0.00
178.00
6.00
4.09
0.00
180.00
6.00
4.09
0.00
182.00
6.00
4.09
0.00
184.00
6.00
4.09
0.00
186.00
6.00
4.09
0.00
188.00
6.00
4.09
0.00
190.00
6.00
4.09
0.00
192.00
6.00
4.09
0.00
194.00
6.00
4.09
0.00
196.00
6.00
4.09
0.00
198.00
6.00
4.09
0.00
200.00
6.00
4.09
0.00

2020.17-BM P6 Type/1 24-hr 25-yr Concord Rainfall=6.00"
Prepared by {enter your company name here} Page 26
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Pond 3P: (BMP6)
Inflow Area = 9.940 ac, Inflow Depth = 4.09" for 25-yr Concord event
Inflow =
72.49 cfs @
11.96 hrs,
Volume=
3.389 of
Outflow =
15.37 cfs @
12.10 hrs,
Volume=
3.384 af, Atten= 79%, Lag= 8.5 min
Primary =
15.37 cfs @
12.10 hrs,
Volume=
3.384 of
Secondary =
0.00 cfs @
0.00 hrs,
Volume=
0.000 of
Routing by Stor-Ind method, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Peak Elev= 622.56' @ 12.10 hrs Surf.Area= 21,132 sf Storage= 76,260 cf
Plug -Flow detention time= 922.4 min calculated for 3.383 of (100% of inflow)
Center -of -Mass det. time= 921.9 min ( 1,724.1 - 802.2 )
Volume Invert Avail.Storage Storage Description
#1 618.00' 108,921 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic -feet) (cubic -feet)
618.00 12,647 0 0
620.00 16,095 28,742 28,742
622.00 19,943 36,038 64,780
624.00 24,198 44,141 108,921
Device Routing Invert Outlet Devices
#1 Primary 596.11' 18.0" x 18.0' long Culvert RCP, square edge headwall, Ke= 0.500
Outlet Invert= 596.00' S= 0.0061 T Cc= 0.900 n= 0.013
#2 Device 1 618.00' Exfiltration
Head (feet) 0.00 1.00 2.00 3.00 4.00 5.00 6.00
Disch. (cfs) 0.000 0.110 0.154 0.198 0.241 0.285 0.329
#3 Device 1 620.00' 6.0" Vert. Orifice/Grate C= 0.600
#4 Device 1 622.00' 2.00' x 3.00' Horiz. Top of Riser Limited to weir flow C= 0.600
#5 Secondary 623.00' 10.0' long x 16.0' breadth Spillway
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Coef. (English) 2.68 2.70 2.70 2.64 2.63 2.64 2.64 2.63
Primary OutFlow Max=15.37 cfs @ 12.10 hrs HW=622.56' (Free Discharge)
L1=Culvert (Passes 15.37 cfs of 43.13 cfs potential flow)
2=Exfltration (Custom Controls 0.27 cfs)
3=Orifice/Grate (Orifice Controls 1.44 cfs @ 7.32 fps)
=Top of Riser (Weir Controls 13.67 cfs @ 2.44 fps)
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=618.00' (Free Discharge)
5=Spillway ( Controls 0.00 cfs)

2020.17-BM P6
Type // 24-hr 25-yr Concord Rainfall=6.00"
Prepared by {enter your company name here} Page 27
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Hydrograph for Pond 3P: (BMP6)
Time
Inflow
Storage
Elevation
Outflow
Primary
Secondary
(hours)
(cfs)
(cubic -feet)
(feet)
(cfs)
(cfs)
(cfs)
0.00
0.00
0
618.00
0.00
0.00
0.00
5.00
0.00
0
618.00
0.00
0.00
0.00
10.00
1.00
5,551
618.43
0.05
0.05
0.00
15.00
1.67
65,690
622.05
1.88
1.88
0.00
20.00
0.73
58,661
621.69
1.36
1.36
0.00
25.00
0.00
46,441
621.04
1.04
1.04
0.00
30.00
0.00
33,501
620.29
0.38
0.38
0.00
35.00
0.00
29,297
620.03
0.16
0.16
0.00
40.00
0.00
26,559
619.86
0.15
0.15
0.00
45.00
0.00
23,961
619.70
0.14
0.14
0.00
50.00
0.00
21,492
619.54
0.13
0.13
0.00
55.00
0.00
19,147
619.38
0.13
0.13
0.00
60.00
0.00
16,923
619.23
0.12
0.12
0.00
65.00
0.00
14,815
619.09
0.11
0.11
0.00
70.00
0.00
12,828
618.95
0.10
0.10
0.00
75.00
0.00
11,068
618.83
0.09
0.09
0.00
80.00
0.00
9,538
618.72
0.08
0.08
0.00
85.00
0.00
8,212
618.62
0.07
0.07
0.00
90.00
0.00
7,064
618.54
0.06
0.06
0.00
95.00
0.00
6,072
618.47
0.05
0.05
0.00
100.00
0.00
5,215
618.40
0.04
0.04
0.00
105.00
0.00
4,477
618.35
0.04
0.04
0.00
110.00
0.00
3,841
618.30
0.03
0.03
0.00
115.00
0.00
3,294
618.26
0.03
0.03
0.00
120.00
0.00
2,824
618.22
0.02
0.02
0.00
125.00
0.00
2,420
618.19
0.02
0.02
0.00
130.00
0.00
2,073
618.16
0.02
0.02
0.00
135.00
0.00
1,775
618.14
0.02
0.02
0.00
140.00
0.00
1,520
618.12
0.01
0.01
0.00
145.00
0.00
1,302
618.10
0.01
0.01
0.00
150.00
0.00
1,114
618.09
0.01
0.01
0.00
155.00
0.00
954
618.07
0.01
0.01
0.00
160.00
0.00
816
618.06
0.01
0.01
0.00
165.00
0.00
698
618.05
0.01
0.01
0.00
170.00
0.00
597
618.05
0.01
0.01
0.00
175.00
0.00
511
618.04
0.00
0.00
0.00
180.00
0.00
437
618.03
0.00
0.00
0.00
185.00
0.00
374
618.03
0.00
0.00
0.00
190.00
0.00
320
618.03
0.00
0.00
0.00
195.00
0.00
274
618.02
0.00
0.00
0.00
200.00
0.00
234
618.02
0.00
0.00
0.00

2020.17-BM P6
Type // 24-hr 25-yr Concord Rainfall=6.00"
Prepared by {enter your company name here} Page 28
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Stage -Discharge for Pond 3P: (BMP6)
Elevation Discharge Primary Secondary
(feet)
(cfs)
(cfs)
(cfs)
618.00
0.00
0.00
0.00
618.10
0.01
0.01
0.00
618.20
0.02
0.02
0.00
618.30
0.03
0.03
0.00
618.40
0.04
0.04
0.00
618.50
0.06
0.06
0.00
618.60
0.07
0.07
0.00
618.70
0.08
0.08
0.00
618.80
0.09
0.09
0.00
618.90
0.10
0.10
0.00
619.00
0.11
0.11
0.00
619.10
0.11
0.11
0.00
619.20
0.12
0.12
0.00
619.30
0.12
0.12
0.00
619.40
0.13
0.13
0.00
619.50
0.13
0.13
0.00
619.60
0.14
0.14
0.00
619.70
0.14
0.14
0.00
619.80
0.15
0.15
0.00
619.90
0.15
0.15
0.00
620.00
0.15
0.15
0.00
620.10
0.19
0.19
0.00
620.20
0.27
0.27
0.00
620.30
0.40
0.40
0.00
620.40
0.53
0.53
0.00
620.50
0.65
0.65
0.00
620.60
0.74
0.74
0.00
620.70
0.82
0.82
0.00
620.80
0.89
0.89
0.00
620.90
0.96
0.96
0.00
621.00
1.02
1.02
0.00
621.10
1.07
1.07
0.00
621.20
1.13
1.13
0.00
621.30
1.18
1.18
0.00
621.40
1.23
1.23
0.00
621.50
1.28
1.28
0.00
621.60
1.32
1.32
0.00
621.70
1.37
1.37
0.00
621.80
1.41
1.41
0.00
621.90
1.45
1.45
0.00
622.00
1.49
1.49
0.00
622.10
2.57
2.57
0.00
622.20
4.49
4.49
0.00
622.30
6.98
6.98
0.00
622.40
9.92
9.92
0.00
622.50
13.24
13.24
0.00
622.60
16.91
16.91
0.00
622.70
20.90
20.90
0.00
622.80
25.18
25.18
0.00
622.90
29.23
29.23
0.00
623.00
30.74
30.74
0.00
623.10
33.03
32.19
0.85
Elevation Discharge Primary Secondary
(feet)
(cfs)
(cfs)
(cfs)
623.20
35.96
33.56
2.40
623.30
39.31
34.89
4.42
623.40
42.99
36.16
6.83
623.50
46.94
37.39
9.55
623.60
51.13
38.58
12.55
623.70
55.38
39.74
15.64
623.80
59.75
40.86
18.89
623.90
64.45
41.95
22.50
624.00
69.32
43.02
26.30

2020.17-BM P6
Type // 24-hr 25-yr Concord Rainfall=6.00"
Prepared by {enter your company name here} Page 29
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Stage -Area -Storage for Pond 3P: (BMP6)
Elevation
Surface
Storage
(feet)
(sq-ft)
(cubic -feet)
618.00
12,647
0
618.10
12,819
1,273
618.20
12,992
2,564
618.30
13,164
3,872
618.40
13,337
5,197
618.50
13,509
6,539
618.60
13,681
7,899
618.70
13,854
9,275
618.80
14,026
10,669
618.90
14,199
12,081
619.00
14,371
13,509
619.10
14,543
14,955
619.20
14,716
16,418
619.30
14,888
17,898
619.40
15,061
19,395
619.50
15,233
20,910
619.60
15,405
22,442
619.70
15,578
23,991
619.80
15,750
25,557
619.90
15,923
27,141
620.00
16,095
28,742
620.10
16,287
30,361
620.20
16,480
31,999
620.30
16,672
33,657
620.40
16,865
35,334
620.50
17,057
37,030
620.60
17,249
38,745
620.70
17,442
40,480
620.80
17,634
42,234
620.90
17,827
44,007
621.00
18,019
45,799
621.10
18,211
47,611
621.20
18,404
49,441
621.30
18,596
51,291
621.40
18,789
53,161
621.50
18,981
55,049
621.60
19,173
56,957
621.70
19,366
58,884
621.80
19,558
60,830
621.90
19,751
62,795
622.00
19,943
64,780
622.10
20,156
66,785
622.20
20,369
68,811
622.30
20,581
70,859
622.40
20,794
72,927
622.50
21,007
75,017
622.60
21,220
77,129
622.70
21,432
79,261
622.80
21,645
81,415
622.90
21,858
83,590
623.00
22,071
85,787
623.10
22,283
88,004
Elevation
Surface
Storage
(feet)
(sq-ft)
(cubic -feet)
623.20
22,496
90,243
623.30
22,709
92,504
623.40
22,921
94,785
623.50
23,134
97,088
623.60
23,347
99,412
623.70
23,560
101,757
623.80
23,772
104,124
623.90
23,985
106,512
624.00
24,198
108,921

2020.17-BM P6 Type 11 24-hr 50-yr Concord Rainfall=6.80"
Prepared by {enter your company name here} Page 30
HvdroCAD® 8.00 s/n 004317 © 2006 HvdroCAD Software Solutions LLC 6/5/2022
Time span=0.00-200.00 hrs, dt=0.01 hrs, 20001 points
Runoff by SCS TR-20 method, UH=SCS
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment 1S: (Predeveloped) Runoff Area=9.940 ac Runoff Depth=3.87"
Flow Length=598' Tc=37.6 min CN=74 Runoff=28.71 cfs 3.204 of
Subcatchment 2S: (Post Developed) Runoff Area=9.940 ac Runoff Depth=4.84"
Tc=5.0 min CN=83 Runoff=84.89 cfs 4.009 of
Pond 3P: (BMP6) Peak Elev=622.97' Storage=85,205 cf Inflow=84.89 cfs 4.009 of
Primary=30.35 cfs 4.003 of Secondary=0.00 cfs 0.000 of Outflow=30.35 cfs 4.003 of
Total Runoff Area = 19.880 ac Runoff Volume = 7.213 of Average Runoff Depth = 4.35"
100.00% Pervious Area = 19.880 ac 0.00% Impervious Area = 0.000 ac

2020.17-BM P6 Type 11 24-hr 50-yr Concord Rainfall=6.80"
Prepared by {enter your company name here} Page 31
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Subcatchment 1S: (Predeveloped)
BASED ON EXISTING CONDITIONS
Runoff = 28.71 cfs @ 12.33 hrs, Volume= 3.204 af, Depth= 3.87"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Type II 24-hr 50-yr Concord Rainfall=6.80"
Area (ac)
CN
Description
8.510
73
Woods, Fair, HSG C
1.430
79
Pasture/grassland/range, Fair, HSG C
9.940
74
Weighted Average
9.940
Pervious Area
Tc
Length
Slope
Velocity
Capacity Description
(min)
(feet)
(ft/ft)
(ft/sec)
(cfs)
32.8
100
0.0248
0.05
Sheet Flow,
Woods: Dense underbrush n= 0.800 P2= 3.50"
4.8
498
0.1210
1.74
Shallow Concentrated Flow,
Woodland Kv= 5.0 fps

2020.17-BM P6
Type // 24-hr 50-yr Concord Rainfall=6.80"
Prepared by {enter your company name here} Page 32
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Hydrograph for Subcatchment 1S: (Predeveloped)
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
0.00
0.00
0.00
0.00
2.00
0.15
0.00
0.00
4.00
0.33
0.00
0.00
6.00
0.54
0.00
0.00
8.00
0.82
0.00
0.03
10.00
1.23
0.07
0.43
12.00
4.51
1.98
9.76
14.00
5.58
2.83
2.83
16.00
5.98
3.17
1.54
18.00
6.26
3.41
1.12
20.00
6.47
3.59
0.84
22.00
6.64
3.73
0.72
24.00
6.80
3.87
0.67
26.00
6.80
3.87
0.00
28.00
6.80
3.87
0.00
30.00
6.80
3.87
0.00
32.00
6.80
3.87
0.00
34.00
6.80
3.87
0.00
36.00
6.80
3.87
0.00
38.00
6.80
3.87
0.00
40.00
6.80
3.87
0.00
42.00
6.80
3.87
0.00
44.00
6.80
3.87
0.00
46.00
6.80
3.87
0.00
48.00
6.80
3.87
0.00
50.00
6.80
3.87
0.00
52.00
6.80
3.87
0.00
54.00
6.80
3.87
0.00
56.00
6.80
3.87
0.00
58.00
6.80
3.87
0.00
60.00
6.80
3.87
0.00
62.00
6.80
3.87
0.00
64.00
6.80
3.87
0.00
66.00
6.80
3.87
0.00
68.00
6.80
3.87
0.00
70.00
6.80
3.87
0.00
72.00
6.80
3.87
0.00
74.00
6.80
3.87
0.00
76.00
6.80
3.87
0.00
78.00
6.80
3.87
0.00
80.00
6.80
3.87
0.00
82.00
6.80
3.87
0.00
84.00
6.80
3.87
0.00
86.00
6.80
3.87
0.00
88.00
6.80
3.87
0.00
90.00
6.80
3.87
0.00
92.00
6.80
3.87
0.00
94.00
6.80
3.87
0.00
96.00
6.80
3.87
0.00
98.00
6.80
3.87
0.00
100.00
6.80
3.87
0.00
102.00
6.80
3.87
0.00
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
104.00
6.80
3.87
0.00
106.00
6.80
3.87
0.00
108.00
6.80
3.87
0.00
110.00
6.80
3.87
0.00
112.00
6.80
3.87
0.00
114.00
6.80
3.87
0.00
116.00
6.80
3.87
0.00
118.00
6.80
3.87
0.00
120.00
6.80
3.87
0.00
122.00
6.80
3.87
0.00
124.00
6.80
3.87
0.00
126.00
6.80
3.87
0.00
128.00
6.80
3.87
0.00
130.00
6.80
3.87
0.00
132.00
6.80
3.87
0.00
134.00
6.80
3.87
0.00
136.00
6.80
3.87
0.00
138.00
6.80
3.87
0.00
140.00
6.80
3.87
0.00
142.00
6.80
3.87
0.00
144.00
6.80
3.87
0.00
146.00
6.80
3.87
0.00
148.00
6.80
3.87
0.00
150.00
6.80
3.87
0.00
152.00
6.80
3.87
0.00
154.00
6.80
3.87
0.00
156.00
6.80
3.87
0.00
158.00
6.80
3.87
0.00
160.00
6.80
3.87
0.00
162.00
6.80
3.87
0.00
164.00
6.80
3.87
0.00
166.00
6.80
3.87
0.00
168.00
6.80
3.87
0.00
170.00
6.80
3.87
0.00
172.00
6.80
3.87
0.00
174.00
6.80
3.87
0.00
176.00
6.80
3.87
0.00
178.00
6.80
3.87
0.00
180.00
6.80
3.87
0.00
182.00
6.80
3.87
0.00
184.00
6.80
3.87
0.00
186.00
6.80
3.87
0.00
188.00
6.80
3.87
0.00
190.00
6.80
3.87
0.00
192.00
6.80
3.87
0.00
194.00
6.80
3.87
0.00
196.00
6.80
3.87
0.00
198.00
6.80
3.87
0.00
200.00
6.80
3.87
0.00

2020.17-BM P6
Type 11 24-hr 50-yr Concord Rainfall=6.80"
Prepared by {enter your company name here} Page 33
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Subcatchment 2S: (Post Developed)
Runoff = 84.89 cfs @ 11.96 hrs, Volume= 4.009 af, Depth= 4.84"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Type II 24-hr 50-yr Concord Rainfall=6.80"
Area (ac) CN Description
9.940 83 RM-2 (C)
9.940 Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,

2020.17-BM P6
Type // 24-hr 50-yr Concord Rainfall=6.80"
Prepared by {enter your company name here} Page 34
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Hydrograph for Subcatchment 2S: (Post Developed)
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
0.00
0.00
0.00
0.00
2.00
0.15
0.00
0.00
4.00
0.33
0.00
0.00
6.00
0.54
0.01
0.14
8.00
0.82
0.07
0.44
10.00
1.23
0.24
1.28
12.00
4.51
2.73
71.36
14.00
5.58
3.70
2.41
16.00
5.98
4.08
1.49
18.00
6.26
4.34
1.16
20.00
6.47
4.53
0.84
22.00
6.64
4.69
0.77
24.00
6.80
4.84
0.71
26.00
6.80
4.84
0.00
28.00
6.80
4.84
0.00
30.00
6.80
4.84
0.00
32.00
6.80
4.84
0.00
34.00
6.80
4.84
0.00
36.00
6.80
4.84
0.00
38.00
6.80
4.84
0.00
40.00
6.80
4.84
0.00
42.00
6.80
4.84
0.00
44.00
6.80
4.84
0.00
46.00
6.80
4.84
0.00
48.00
6.80
4.84
0.00
50.00
6.80
4.84
0.00
52.00
6.80
4.84
0.00
54.00
6.80
4.84
0.00
56.00
6.80
4.84
0.00
58.00
6.80
4.84
0.00
60.00
6.80
4.84
0.00
62.00
6.80
4.84
0.00
64.00
6.80
4.84
0.00
66.00
6.80
4.84
0.00
68.00
6.80
4.84
0.00
70.00
6.80
4.84
0.00
72.00
6.80
4.84
0.00
74.00
6.80
4.84
0.00
76.00
6.80
4.84
0.00
78.00
6.80
4.84
0.00
80.00
6.80
4.84
0.00
82.00
6.80
4.84
0.00
84.00
6.80
4.84
0.00
86.00
6.80
4.84
0.00
88.00
6.80
4.84
0.00
90.00
6.80
4.84
0.00
92.00
6.80
4.84
0.00
94.00
6.80
4.84
0.00
96.00
6.80
4.84
0.00
98.00
6.80
4.84
0.00
100.00
6.80
4.84
0.00
102.00
6.80
4.84
0.00
Time Precip. Excess Runoff
(hours)
(inches)
(inches)
(cfs)
104.00
6.80
4.84
0.00
106.00
6.80
4.84
0.00
108.00
6.80
4.84
0.00
110.00
6.80
4.84
0.00
112.00
6.80
4.84
0.00
114.00
6.80
4.84
0.00
116.00
6.80
4.84
0.00
118.00
6.80
4.84
0.00
120.00
6.80
4.84
0.00
122.00
6.80
4.84
0.00
124.00
6.80
4.84
0.00
126.00
6.80
4.84
0.00
128.00
6.80
4.84
0.00
130.00
6.80
4.84
0.00
132.00
6.80
4.84
0.00
134.00
6.80
4.84
0.00
136.00
6.80
4.84
0.00
138.00
6.80
4.84
0.00
140.00
6.80
4.84
0.00
142.00
6.80
4.84
0.00
144.00
6.80
4.84
0.00
146.00
6.80
4.84
0.00
148.00
6.80
4.84
0.00
150.00
6.80
4.84
0.00
152.00
6.80
4.84
0.00
154.00
6.80
4.84
0.00
156.00
6.80
4.84
0.00
158.00
6.80
4.84
0.00
160.00
6.80
4.84
0.00
162.00
6.80
4.84
0.00
164.00
6.80
4.84
0.00
166.00
6.80
4.84
0.00
168.00
6.80
4.84
0.00
170.00
6.80
4.84
0.00
172.00
6.80
4.84
0.00
174.00
6.80
4.84
0.00
176.00
6.80
4.84
0.00
178.00
6.80
4.84
0.00
180.00
6.80
4.84
0.00
182.00
6.80
4.84
0.00
184.00
6.80
4.84
0.00
186.00
6.80
4.84
0.00
188.00
6.80
4.84
0.00
190.00
6.80
4.84
0.00
192.00
6.80
4.84
0.00
194.00
6.80
4.84
0.00
196.00
6.80
4.84
0.00
198.00
6.80
4.84
0.00
200.00
6.80
4.84
0.00

2020.17-BM P6 Type 11 24-hr 50-yr Concord Rainfall=6.80"
Prepared by {enter your company name here} Page 35
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Pond 3P: (BMP6)
Inflow Area = 9.940 ac, Inflow Depth = 4.84" for 50-yr Concord event
Inflow =
84.89 cfs @
11.96 hrs,
Volume=
4.009 of
Outflow =
30.35 cfs @
12.06 hrs,
Volume=
4.003 af, Atten= 64%, Lag= 6.2 min
Primary =
30.35 cfs @
12.06 hrs,
Volume=
4.003 of
Secondary =
0.00 cfs @
0.00 hrs,
Volume=
0.000 of
Routing by Stor-Ind method, Time Span= 0.00-200.00 hrs, dt= 0.01 hrs
Peak Elev= 622.97' @ 12.06 hrs Surf.Area= 22,014 sf Storage= 85,205 cf
Plug -Flow detention time= 801.5 min calculated for 4.003 of (100% of inflow)
Center -of -Mass det. time= 800.6 min ( 1,598.1 - 797.5 )
Volume Invert Avail.Storage Storage Description
#1 618.00' 108,921 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic -feet) (cubic -feet)
618.00 12,647 0 0
620.00 16,095 28,742 28,742
622.00 19,943 36,038 64,780
624.00 24,198 44,141 108,921
Device Routing Invert Outlet Devices
#1 Primary 596.11' 18.0" x 18.0' long Culvert RCP, square edge headwall, Ke= 0.500
Outlet Invert= 596.00' S= 0.0061 T Cc= 0.900 n= 0.013
#2 Device 1 618.00' Exfiltration
Head (feet) 0.00 1.00 2.00 3.00 4.00 5.00 6.00
Disch. (cfs) 0.000 0.110 0.154 0.198 0.241 0.285 0.329
#3 Device 1 620.00' 6.0" Vert. Orifice/Grate C= 0.600
#4 Device 1 622.00' 2.00' x 3.00' Horiz. Top of Riser Limited to weir flow C= 0.600
#5 Secondary 623.00' 10.0' long x 16.0' breadth Spillway
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Coef. (English) 2.68 2.70 2.70 2.64 2.63 2.64 2.64 2.63
Primary OutFlow Max=30.34 cfs @ 12.06 hrs HW=622.97' (Free Discharge)
L1=Culvert (Passes 30.34 cfs of 43.48 cfs potential flow)
2=Exfltration (Custom Controls 0.28 cfs)
3=Orifice/Grate (Orifice Controls 1.56 cfs @ 7.95 fps)
=Top of Riser (Orifice Controls 28.49 cfs @ 4.75 fps)
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=618.00' (Free Discharge)
5=Spillway ( Controls 0.00 cfs)

2020.17-BM P6
Type // 24-hr 50-yr Concord Rainfall=6.80"
Prepared by {enter your company name here} Page 36
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Hydrograph for Pond 3P: (BMP6)
Time
Inflow
Storage
Elevation
Outflow
Primary
Secondary
(hours)
(cfs)
(cubic -feet)
(feet)
(cfs)
(cfs)
(cfs)
0.00
0.00
0
618.00
0.00
0.00
0.00
5.00
0.01
2
618.00
0.00
0.00
0.00
10.00
1.28
7,770
618.59
0.06
0.06
0.00
15.00
1.92
66,140
622.07
2.13
2.13
0.00
20.00
0.84
60,655
621.79
1.41
1.41
0.00
25.00
0.00
48,818
621.17
1.11
1.11
0.00
30.00
0.00
34,433
620.35
0.46
0.46
0.00
35.00
0.00
29,659
620.06
0.17
0.17
0.00
40.00
0.00
26,887
619.88
0.15
0.15
0.00
45.00
0.00
24,273
619.72
0.14
0.14
0.00
50.00
0.00
21,788
619.56
0.13
0.13
0.00
55.00
0.00
19,429
619.40
0.13
0.13
0.00
60.00
0.00
17,190
619.25
0.12
0.12
0.00
65.00
0.00
15,068
619.11
0.11
0.11
0.00
70.00
0.00
13,062
618.97
0.11
0.11
0.00
75.00
0.00
11,271
618.84
0.09
0.09
0.00
80.00
0.00
9,715
618.73
0.08
0.08
0.00
85.00
0.00
8,365
618.63
0.07
0.07
0.00
90.00
0.00
7,196
618.55
0.06
0.06
0.00
95.00
0.00
6,186
618.47
0.05
0.05
0.00
100.00
0.00
5,314
618.41
0.04
0.04
0.00
105.00
0.00
4,562
618.35
0.04
0.04
0.00
110.00
0.00
3,914
618.30
0.03
0.03
0.00
115.00
0.00
3,357
618.26
0.03
0.03
0.00
120.00
0.00
2,878
618.22
0.02
0.02
0.00
125.00
0.00
2,466
618.19
0.02
0.02
0.00
130.00
0.00
2,113
618.17
0.02
0.02
0.00
135.00
0.00
1,810
618.14
0.02
0.02
0.00
140.00
0.00
1,550
618.12
0.01
0.01
0.00
145.00
0.00
1,327
618.10
0.01
0.01
0.00
150.00
0.00
1,136
618.09
0.01
0.01
0.00
155.00
0.00
972
618.08
0.01
0.01
0.00
160.00
0.00
832
618.07
0.01
0.01
0.00
165.00
0.00
712
618.06
0.01
0.01
0.00
170.00
0.00
609
618.05
0.01
0.01
0.00
175.00
0.00
521
618.04
0.00
0.00
0.00
180.00
0.00
446
618.04
0.00
0.00
0.00
185.00
0.00
381
618.03
0.00
0.00
0.00
190.00
0.00
326
618.03
0.00
0.00
0.00
195.00
0.00
279
618.02
0.00
0.00
0.00
200.00
0.00
239
618.02
0.00
0.00
0.00

2020.17-BM P6
Type // 24-hr 50-yr Concord Rainfall=6.80"
Prepared by {enter your company name here} Page 37
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Stage -Discharge for Pond 3P: (BMP6)
Elevation Discharge Primary Secondary
(feet)
(cfs)
(cfs)
(cfs)
618.00
0.00
0.00
0.00
618.10
0.01
0.01
0.00
618.20
0.02
0.02
0.00
618.30
0.03
0.03
0.00
618.40
0.04
0.04
0.00
618.50
0.06
0.06
0.00
618.60
0.07
0.07
0.00
618.70
0.08
0.08
0.00
618.80
0.09
0.09
0.00
618.90
0.10
0.10
0.00
619.00
0.11
0.11
0.00
619.10
0.11
0.11
0.00
619.20
0.12
0.12
0.00
619.30
0.12
0.12
0.00
619.40
0.13
0.13
0.00
619.50
0.13
0.13
0.00
619.60
0.14
0.14
0.00
619.70
0.14
0.14
0.00
619.80
0.15
0.15
0.00
619.90
0.15
0.15
0.00
620.00
0.15
0.15
0.00
620.10
0.19
0.19
0.00
620.20
0.27
0.27
0.00
620.30
0.40
0.40
0.00
620.40
0.53
0.53
0.00
620.50
0.65
0.65
0.00
620.60
0.74
0.74
0.00
620.70
0.82
0.82
0.00
620.80
0.89
0.89
0.00
620.90
0.96
0.96
0.00
621.00
1.02
1.02
0.00
621.10
1.07
1.07
0.00
621.20
1.13
1.13
0.00
621.30
1.18
1.18
0.00
621.40
1.23
1.23
0.00
621.50
1.28
1.28
0.00
621.60
1.32
1.32
0.00
621.70
1.37
1.37
0.00
621.80
1.41
1.41
0.00
621.90
1.45
1.45
0.00
622.00
1.49
1.49
0.00
622.10
2.57
2.57
0.00
622.20
4.49
4.49
0.00
622.30
6.98
6.98
0.00
622.40
9.92
9.92
0.00
622.50
13.24
13.24
0.00
622.60
16.91
16.91
0.00
622.70
20.90
20.90
0.00
622.80
25.18
25.18
0.00
622.90
29.23
29.23
0.00
623.00
30.74
30.74
0.00
623.10
33.03
32.19
0.85
Elevation Discharge Primary Secondary
(feet)
(cfs)
(cfs)
(cfs)
623.20
35.96
33.56
2.40
623.30
39.31
34.89
4.42
623.40
42.99
36.16
6.83
623.50
46.94
37.39
9.55
623.60
51.13
38.58
12.55
623.70
55.38
39.74
15.64
623.80
59.75
40.86
18.89
623.90
64.45
41.95
22.50
624.00
69.32
43.02
26.30

2020.17-BM P6
Type // 24-hr 50-yr Concord Rainfall=6.80"
Prepared by {enter your company name here} Page 38
HydroCAD® 8.00 s/n 004317 © 2006 HydroCAD Software Solutions LLC 6/5/2022
Stage -Area -Storage for Pond 3P: (BMP6)
Elevation
Surface
Storage
(feet)
(sq-ft)
(cubic -feet)
618.00
12,647
0
618.10
12,819
1,273
618.20
12,992
2,564
618.30
13,164
3,872
618.40
13,337
5,197
618.50
13,509
6,539
618.60
13,681
7,899
618.70
13,854
9,275
618.80
14,026
10,669
618.90
14,199
12,081
619.00
14,371
13,509
619.10
14,543
14,955
619.20
14,716
16,418
619.30
14,888
17,898
619.40
15,061
19,395
619.50
15,233
20,910
619.60
15,405
22,442
619.70
15,578
23,991
619.80
15,750
25,557
619.90
15,923
27,141
620.00
16,095
28,742
620.10
16,287
30,361
620.20
16,480
31,999
620.30
16,672
33,657
620.40
16,865
35,334
620.50
17,057
37,030
620.60
17,249
38,745
620.70
17,442
40,480
620.80
17,634
42,234
620.90
17,827
44,007
621.00
18,019
45,799
621.10
18,211
47,611
621.20
18,404
49,441
621.30
18,596
51,291
621.40
18,789
53,161
621.50
18,981
55,049
621.60
19,173
56,957
621.70
19,366
58,884
621.80
19,558
60,830
621.90
19,751
62,795
622.00
19,943
64,780
622.10
20,156
66,785
622.20
20,369
68,811
622.30
20,581
70,859
622.40
20,794
72,927
622.50
21,007
75,017
622.60
21,220
77,129
622.70
21,432
79,261
622.80
21,645
81,415
622.90
21,858
83,590
623.00
22,071
85,787
623.10
22,283
88,004
Elevation
Surface
Storage
(feet)
(sq-ft)
(cubic -feet)
623.20
22,496
90,243
623.30
22,709
92,504
623.40
22,921
94,785
623.50
23,134
97,088
623.60
23,347
99,412
623.70
23,560
101,757
623.80
23,772
104,124
623.90
23,985
106,512
624.00
24,198
108,921