Southern Asphalt - Narrative and Calcs - Erosion Control and StormwaterF:\GSandE\01-20_New Hanover\43 Southern Asphalt\Permitting\County Erosion & Storm\20-43 County-Narrative.doc
DESIGN NARRATIVE
1. GENERAL:
Introduction
The Southern Asphalt Facility site is located approximately 1-1/2 miles east of the I-40, Castle
Hayne/ Holly Shelter interchange in unincorporated New Hanover County, North Carolina.
Project Owner: FSS Properties, LLC
Mr. James Sanderford
5993 HWY 117 South
Burgaw, NC 28425
Project Designer: GS&E, Inc.
PO Box 16110
Wilmington, NC 28408
The project is proposed for construction of a new Asphalt Batch Plant with onsite offices,
parking and site improvements.
General Site Characterization
The project site is a former dirt-track, motorsports park. The site has an existing bath-house with
ADA parking, concession stand, observation tower, site lighting, along with miscellaneous other
improvements.
From research with New Hanover County and NCDEQ, there appears to be no existing land
disturbance permits from previous work and, although a pond and pond outfall exist on the site,
we have determined it is not a permitted stormwater facility.
The bath-house, parking and site lighting are to remain. The existing pond will be enlarged and
serve as an erosion control feature and a stormwater facility.
The area for development drains from north to south toward the existing pond, discharging to the
existing perimeter ditching, and on to an unnamed tributary to sturgeon creek.
The approximate acreage of land to be disturbed is 7.5 Acres.
County Stormwater
As the site lies within New Hanover County, the project is designed to attenuate stormwater
runoff for the 2, 10 and 25 year storm events.
F:\GSandE\01-20_New Hanover\43 Southern Asphalt\Permitting\County Erosion & Storm\20-43 County-Narrative.doc
For the onsite drainage area, flows will be conveyed over the improved surfaces of the site to the
pipe and swale systems, and to the detention basin forebay.
Drainage outside of the Limits of disturbance are considered grandfathered, as the site’s access
has been paved/ utilized prior to advent of local and state stormwater regulations. These areas are
stabilized and drain to NCDOT roadside facilities or to the existing perimeter ditches.
Stormwater runoff characterization and sizing for the drainage systems were modeled using
Hydrology Studio 2019.
State Stormwater
A state stormwater permit is being sought concurrently with County development permits. For
this reason, the wet-detention basin BMP detailed in this submittal is also designed to
accommodate NCDEMLR requirements for stormwater.
2. EXISTING SITE:
Current topography is largely flat. Perimeter ditches drain the site along all sides. Current slopes
are generally less than 1%. Native soils appear well-drained based on the existing perimeter ditch
configuration with no apparent hydric soils on site.
3. EROSION CONTROL CONSIDERATIONS:
With the design of a properly sized stormwater BMP lying on the downslope end of the proposed
development, sediment will be collected by using this basin as a construction phase sediment
BMP.
For that reason, runoff will be controlled through a skimmer drawdown device until the site is
permanently stabilized.
Calculations are included for the sediment basin and energy dissipaters shown on the plan. Silt
fencing will be used where needed or as directed by the owner or engineer. The area of
disturbance is within the project area.
4. MAINTENANCE CONSIDERATIONS:
During construction, the Contractor shall be required to inspect and repair as needed all erosion
control devices after any significant rain event. Any measure found not performing its intended
function, shall be repaired immediately. Upon completion of construction, the establishment of
permanent ground cover will be a priority.
F:\GSandE\01-20_New Hanover\43 Southern Asphalt\Permitting\County Erosion & Storm\20-43 County-Narrative.doc
Erosion Control Specifications
F:\GSandE\01-20_New Hanover\43 Southern Asphalt\Permitting\County Erosion & Storm\20-43 County-Narrative.doc
Erosion and Sedimentation Control
1.01 General: The contractor shall be responsible for erosion and sedimentation control
within the construction limits; for prevention of sediment laden runoff leaving the construction
limits or entering ditches, streams or water impoundments; and for implementation of necessary
erosion and sedimentation control measures to meet the requirements of the North Carolina
Department of Environment, Health, and Natural Resources. The Contractor shall also be
responsible for all damages or fines resulting from erosion or sediment laden runoff in the
execution of his contract.
1.02 Construction Sequence: Erosion control measures shall be installed prior to the
commencement of land clearing and shall be fully maintained and periodically inspected until
final restoration and stabilization is completed. Unrestored cleared areas shall be kept to a
minimum. Disturbed areas ahead of construction shall only be accomplished on those segments
for the shortest practical distance as required for continual progress.
Final restoration shall not be delayed until completion of the project but will be carried out in
phases as the work proceeds. Under no circumstances will any areas be left denuded for more
than (15) fifteen working days without some form of stabilization until final restoration is
complete.
1.03 Sedimentation: Control Measures: The following are some of the sediment control
devices or measures that may be required to prevent sedimentation of streams, water courses, or
drainage structures:
1. Earth berms and/or diversion and intercept ditches.
2. Sediment traps
3. Filter berms
4. Filter inlets
5. Silt fences - not to be placed in streams or ditches perpendicular to flow.
6. Check dams gravel filter
7. Gravel construction exit
1.03.1 Erosion Control Measures: Some of the soil erosion control measures which may be
required in this contract are:
1. Earth slope protection
2. Diagonal water breaks/ diversion berms
3. Diversion channels
4. Preservation of existing vegetation
5. Storm inlet protection
6. Stream crossings
7. Energy dissipaters
8. Matting of re-seeded areas
F:\GSandE\01-20_New Hanover\43 Southern Asphalt\Permitting\County Erosion & Storm\20-43 County-Narrative.doc
1.03.2 Detail Drawing: Examples of sedimentation and erosion control details are shown in
these plans for installation at locations designated in the plans or as otherwise required by the
regulating agency, or the owner as work proceeds.
1.04 Stream Protection: Where construction activities are necessary in close proximity to
streams, and other waterways, they shall be performed in a manner that does not contribute to
degradation of or blockage of the stream-flow. In order to prevent possible degradation or
blockages, the contractor shall be required to:
1. Keep all construction debris, excavated materials, brush, rocks, refuse and topsoil as far
from these waterways as possible. Restrict machinery operation or stream crossings in
waterways to the extent necessary for construction of utilities crossings.
2. If construction work areas are necessary in a waterway, they shall be protected as
indicated on the plans.
3. If temporary roadways are essential for the construction activities, they shall be
constructed of soils which are not highly erodible materials and must not span more than half
way across the water course or wetland area at any one time unless otherwise approved by the
Engineer. These temporary roadways shall be entirely removed as soon as their requirement is
met. Work in these areas shall follow the requirements of the Corp of Engineers or CAMA
permit, or plans as applicable.
1.05 Construction Access: The travel of equipment to and from the construction areas shall
be minimized not only to protect areas that will not be denuded, but also to prevent the spreading
of sediment within and outside of the construction areas. Therefore, special construction
equipment travel corridors will be established for this use and instructions shall be issued for
their use. Use of these corridors must be fully enforced. Other non-essential traffic will be
restricted or discouraged. Indiscriminate and convenience traffic shall not be allowed.
1.06 Stockpile/Barrow Areas: The Contractor shall be responsible for selecting, obtaining
and maintaining stockpile or borrow areas which may be required to complete the contract. The
Contractor is also required to design and incorporate all necessary sediment and erosion controls
measures necessary to prevent erosion and contribution of sediment to adjacent areas. The
Contractor is responsible to obtain all necessary permits or approvals for borrow or spoil areas
outside the construction limits.
1.07 Disposal of Excess Water from Excavations: The Contractor shall practice
management of excess water pumped from excavation to reduce the production and spreading of
sediment. Pumped water shall be discharged onto stabilized surfaces and allowed to filter
through existing vegetation if possible, otherwise, additional control measures may be necessary.
If ditches are required to remove pumped water from construction excavations, they shall be
given the same consideration as any other man-made waterway and they shall be stabilized as to
not degrade and produce sediment.
F:\GSandE\01-20_New Hanover\43 Southern Asphalt\Permitting\County Erosion & Storm\20-43 County-Narrative.doc
1.08 Excavation and Backfill: Excavation shall be closely controlled and all the material
removed from the excavation shall be selectively stockpiled in areas where a minimum of
sediment will be generated and where other damage will not result from the piled material.
Drainage ways shall be protected at all times and the placement of material in Drainage ways for
convenience shall not be allowed. Backfilling operations shall be performed in such a manner
that remaining trees are not damaged.
1.09 Final Grading and Seeding: Finish grading, topsoiling, seeding and/or sodding shall be
performed after the construction phase is complete. Permanent vegetation of the areas, that have
been disturbed, shall be re-established as rapidly as possible. If the completion of the
construction activities do not coincide with a season in which permanent vegetation can be
generated, an interim or temporary program is required. This shall include soil conditioners and
mulching as necessary for soil stabilization. In any case, sediment and erosion controls shall be
installed promptly and their maintenance assured.
1.10 Approval: The approved Erosion Control Plan will be provided by the Owner. Any
standard conditions relating to soil erosion and sediment control issued to the Contractor as a part
of any permits shall be available at the job site at all times.
Table of Contents Project Name:
Hydrology Studio v 3.0.0.13 02-27-2020
2 -Year
Hydrograph Summary 1..................................................................................................................................
Hydrograph Reports
Hydrograph No. 1, NRCS Runoff, Post-Dev2............................................................................................
Hydrograph No. 2, NRCS Runoff, Post-Dev3............................................................................................
Hydrograph No. 3, Pond Route, Developed pond Count4............................................................................
Detention Pond Reports -Pre-Post Pond5...................................................................................
Design Storm Report -NRCS/SCS -Type II9................................................................................
10 -Year
Hydrograph Summary 10................................................................................................................................
Hydrograph Reports
Hydrograph No. 1, NRCS Runoff, Post-Dev11..........................................................................................
Hydrograph No. 2, NRCS Runoff, Post-Dev12..........................................................................................
Hydrograph No. 3, Pond Route, Developed pond Count13..........................................................................
Design Storm Report -NRCS/SCS -Type II14..............................................................................
25 -Year
Hydrograph Summary 15................................................................................................................................
Hydrograph Reports
Hydrograph No. 1, NRCS Runoff, Post-Dev16..........................................................................................
Hydrograph No. 2, NRCS Runoff, Post-Dev17..........................................................................................
Hydrograph No. 3, Pond Route, Developed pond Count18..........................................................................
Design Storm Report -NRCS/SCS -Type II19..............................................................................
100 -Year
Hydrograph Summary 20................................................................................................................................
Hydrograph Reports
Hydrograph No. 1, NRCS Runoff, Post-Dev21..........................................................................................
Hydrograph No. 2, NRCS Runoff, Post-Dev22..........................................................................................
Hydrograph No. 3, Pond Route, Developed pond Count23..........................................................................
Design Storm Report -NRCS/SCS -Type II24..............................................................................
Hydrograph 2-yr Summary Project Name:
Hydrology Studio v 3.0.0.13 02-27-2020
Hyd.
No.
Hydrograph
Type
Hydrograph
Name
Peak
Flow
(cfs)
Time to
Peak
(hrs)
Hydrograph
Volume
(cuft)
Inflow
Hyd(s)
Maximum
Elevation
(ft)
Maximum
Storage
(cuft)
1NRCS RunoffPost-Dev5.27012.6743,389----
2NRCS RunoffPost-Dev21.5412.1786,884----
3Pond RouteDeveloped pond Count1.30714.1062,703222.9459,376
1
Hydrograph Report Project Name:
Hydrology Studio v 3.0.0.13 02-27-2020
Post-DevHyd. No. 1
Hydrograph Type= NRCS RunoffPeak Flow= 5.270 cfs
Storm Frequency= 2-yrTime to Peak= 12.67 hrs
Time Interval= 2 minRunoff Volume= 43,389 cuft
Drainage Area= 7.5 acCurve Number= 69
Tc Method= LagTime of Conc. (Tc)= 74.8 min
Basin Slope= 0.5 %Hydraulic Length= 1273 ft
Total Rainfall= 4.50 inDesign Storm= Type II
Storm Duration= 24 hrsShape Factor= 484
Time (hrs)
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26
Q
(
c
f
s
)
0
1
2
3
4
5
6
Qp = 5.27 cfs
2
Hydrograph Report Project Name:
Hydrology Studio v 3.0.0.13 02-27-2020
Post-DevHyd. No. 2
Hydrograph Type= NRCS RunoffPeak Flow= 21.54 cfs
Storm Frequency= 2-yrTime to Peak= 12.17 hrs
Time Interval= 2 minRunoff Volume= 86,884 cuft
Drainage Area= 7.5 acCurve Number= 87.95*
Tc Method= LagTime of Conc. (Tc)= 30.2 min
Basin Slope= 0.5 %Hydraulic Length= 855 ft
Total Rainfall= 4.50 inDesign Storm= Type II
Storm Duration= 24 hrsShape Factor= 484
* Composite CN Worksheet
AREA (ac)CNDESCRIPTION
2.669Undisturbed
4.998IMPERVIOUS
7.588 Weighted CN Method Employed
Time (hrs)
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
Q
(
c
f
s
)
0
2
4
6
8
10
12
14
16
18
20
22
24
Qp = 21.54 cfs
3
Hydrograph Report Project Name:
Hydrology Studio v 3.0.0.13 02-27-2020
Developed pond CountHyd. No. 3
Hydrograph Type= Pond RoutePeak Flow= 1.307 cfs
Storm Frequency= 2-yrTime to Peak= 14.10 hrs
Time Interval= 2 minHydrograph Volume= 62,703 cuft
Inflow Hydrograph= 2 -Post-DevMax. Elevation= 22.94 ft
Pond Name= Pre-Post PondMax. Storage= 59,376 cuft
Pond Routing by Storage Indication MethodCenter of mass detention time = 22.68 hrs
Post-Dev Developed pond Count
Time (hrs)
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95
Q
(
c
f
s
)
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
Qp = 1.31 cfs
4
Pond Report Project Name:
Hydrology Studio v 3.0.0.13 02-27-2020
Pre-Post PondStage-Storage
DescriptionInput
Stage / Storage Table
Stage
(ft)
Elevation
(ft)
Contour Area
(sqft)
Incr. Storage
(cuft)
Total Storage
(cuft)
User Defined Contours
Bottom Elevation, ft
Voids (%)
Volume Calc
21.00
100.00
None
0.0021.0028,5100.0000.000
1.0022.0030,66629,58829,588
2.0023.0032,87831,77261,360
3.0024.0035,14734,01395,373
4.0025.0037,47336,310131,683
Contours Top of Pond
Total Storage (cuft)
0 20000 40000 60000 80000 100000 120000 140000
El
e
v
(
f
t
)
21
22
23
24
25
St
a
g
e
(
f
t
)
0
1
2
3
4
Stage-Storage
5
Pond Report Project Name:
Hydrology Studio v 3.0.0.13 02-27-2020
Pre-Post PondStage-Discharge
Culvert / Orifices
Rise, in
Span, in
No. Barrels
Invert Elevation, ft
Orifice Coefficient, Co
Length, ft
Barrel Slope, %
N-Value, n
Culvert Orifices
1*23
302
302
11
20.5021.00
0.600.60
50
.5
0.013
Orifice Plate
Orifice Dia, in
No. Orifices
Invert Elevation, ft
Height, ft
Orifice Coefficient, Co
Weirs
Shape / Type
Crest Elevation, ft
Crest Length, ft
Angle, deg
Weir Coefficient, Cw
Riser*Weirs
1*23
Box RectangularBroad Crested
2422.724.5
16330
18.4 (3:1)
3.33.33.3
Ancillary
Exfiltration, in/hr
*Routes through Culvert.
Top of Pond Culvert Riser Orifice Rectangular Broad Crested Total Q
Discharge (cfs)
051015202530354045505560657075
El
e
v
(
f
t
)
21
22
23
24
25
St
a
g
e
(
f
t
)
0
1
2
3
4Stage-Discharge
6
Pond Report Project Name:
Hydrology Studio v 3.0.0.13 02-27-2020
Pre-Post PondStage-Storage-Discharge Summary
Stage
(ft)
Elev.
(ft)
Storage
(cuft)
Culvert
(cfs)
Orifices, cfs
123
Riser
(cfs)
Weirs, cfs
123
Pf Riser
(cfs)
Exfil
(cfs)
User
(cfs)
Total
(cfs)
0.0021.000.0000.000 0.0000.000 0.000 0.000 0.000
1.0022.0029,5880.101 ic0.1010.000 0.000 0.000 0.101
2.0023.0061,3601.772 ic0.1450.000 1.627 0.000 1.772
3.0024.0095,37314.12 oc0.1050.000 14.02 s0.000 14.12
4.0025.00131,68342.22 oc0.0000.000 0.000 36.40 78.62
Suffix key: ic = inlet control, oc = outlet control, s = submerged weir 7
Pond Report Project Name:
Hydrology Studio v 3.0.0.13 02-27-2020
Pre-Post PondPond Drawdown
St
a
g
e
v
s
.
D
r
a
i
n
T
i
m
e
Dr
a
i
n
T
i
m
e
(
H
r
s
)
0
1
0
2
0
3
0
4
0
5
0
6
0
7
0
8
0
9
0
1
0
0
1
1
0
1
2
0
1
3
0
1
4
0
1
5
0
1
6
0
1
7
0
1
8
0
1
9
0
Elev (ft)
2122232425
Stage (ft)
01234
Pr
e
-
P
o
s
t
P
o
n
d
-
D
r
a
i
n
T
i
m
e
8
Design Storm Report Custom Storm filename: 2017-1203first-attempt.cds
Hydrology Studio v 3.0.0.13 02-27-2020
Storm Distribution: NRCS/SCS -Type II
Total Rainfall Volume (in)Storm
Duration 1-yr 2-yr3-yr5-yr10-yr25-yr50-yr100-yr
24 hrs 0.004.500.005.807.008.059.0010.00
Incremental Rainfall Distribution, 2-yr
TimeTimeTimeTimeTimePrecipPrecipPrecipPrecipPrecip
(hrs)(hrs)(hrs)(hrs)(hrs)(in)(in)(in)(in)(in)
10.900.010100
10.930.010300
10.970.010500
11.000.010700
11.030.011039
11.070.011520
11.100.012000
11.130.012480
11.170.012960
11.200.013440
11.230.013920
11.270.014400
11.300.014880
11.330.015360
11.370.015840
11.400.016320
11.430.016800
11.470.017280
11.500.017760
11.530.023954
11.570.035760
11.600.047600
11.630.059440
11.670.071280
11.700.083120
11.730.094960
11.770.108998
11.800.139727
11.830.172660
11.870.205594
11.900.238527
11.930.217677
11.970.142574
12.000.067625
12.030.030084
12.070.028440
12.100.027300
12.130.026160
12.170.025020
12.200.023880
12.230.022740
12.270.021600
12.300.020460
12.330.019320
12.370.018180
12.400.017040
12.430.015900
12.470.014760
12.500.013620
12.530.012921
12.570.012660
12.600.012400
12.630.012140
12.670.011880
12.700.011620
Time (hrs)
0 2 4 6 8 10 12 14 16 18 20 22 24
Pr
e
c
i
p
(
i
n
)
0
1
2
3
4
5
Pr
e
c
i
p
(
i
n
)
0
1
2
3
4
5
9
Hydrograph 10-yr Summary Project Name:
Hydrology Studio v 3.0.0.13 02-27-2020
Hyd.
No.
Hydrograph
Type
Hydrograph
Name
Peak
Flow
(cfs)
Time to
Peak
(hrs)
Hydrograph
Volume
(cuft)
Inflow
Hyd(s)
Maximum
Elevation
(ft)
Maximum
Storage
(cuft)
1NRCS RunoffPost-Dev12.2512.6795,148----
2NRCS RunoffPost-Dev36.9112.17152,126----
3Pond RouteDeveloped pond Count10.1712.60127,688223.7185,476
10
Hydrograph Report Project Name:
Hydrology Studio v 3.0.0.13 02-27-2020
Post-DevHyd. No. 1
Hydrograph Type= NRCS RunoffPeak Flow= 12.25 cfs
Storm Frequency= 10-yrTime to Peak= 12.67 hrs
Time Interval= 2 minRunoff Volume= 95,148 cuft
Drainage Area= 7.5 acCurve Number= 69
Tc Method= LagTime of Conc. (Tc)= 74.8 min
Basin Slope= 0.5 %Hydraulic Length= 1273 ft
Total Rainfall= 7.00 inDesign Storm= Type II
Storm Duration= 24 hrsShape Factor= 484
Time (hrs)
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26
Q
(
c
f
s
)
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
Qp = 12.25 cfs
11
Hydrograph Report Project Name:
Hydrology Studio v 3.0.0.13 02-27-2020
Post-DevHyd. No. 2
Hydrograph Type= NRCS RunoffPeak Flow= 36.91 cfs
Storm Frequency= 10-yrTime to Peak= 12.17 hrs
Time Interval= 2 minRunoff Volume= 152,126 cuft
Drainage Area= 7.5 acCurve Number= 87.95*
Tc Method= LagTime of Conc. (Tc)= 30.2 min
Basin Slope= 0.5 %Hydraulic Length= 855 ft
Total Rainfall= 7.00 inDesign Storm= Type II
Storm Duration= 24 hrsShape Factor= 484
* Composite CN Worksheet
AREA (ac)CNDESCRIPTION
2.669Undisturbed
4.998IMPERVIOUS
7.588 Weighted CN Method Employed
Time (hrs)
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
Q
(
c
f
s
)
0
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
34
36
38
40
42
Qp = 36.91 cfs
12
Hydrograph Report Project Name:
Hydrology Studio v 3.0.0.13 02-27-2020
Developed pond CountHyd. No. 3
Hydrograph Type= Pond RoutePeak Flow= 10.17 cfs
Storm Frequency= 10-yrTime to Peak= 12.60 hrs
Time Interval= 2 minHydrograph Volume= 127,688 cuft
Inflow Hydrograph= 2 -Post-DevMax. Elevation= 23.71 ft
Pond Name= Pre-Post PondMax. Storage= 85,476 cuft
Pond Routing by Storage Indication Method Center of mass detention time = 8.99 hrs
Post-Dev Developed pond Count
Time (hrs)
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95
Q
(
c
f
s
)
0
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
34
36
38
40
42
Qp = 10.17 cfs
13
Design Storm Report Custom Storm filename: 2017-1203first-attempt.cds
Hydrology Studio v 3.0.0.13 02-27-2020
Storm Distribution: NRCS/SCS -Type II
Total Rainfall Volume (in)Storm
Duration 1-yr2-yr3-yr5-yr 10-yr25-yr50-yr100-yr
24 hrs 0.004.500.005.807.008.059.0010.00
Incremental Rainfall Distribution, 10-yr
TimeTimeTimeTimeTimePrecipPrecipPrecipPrecipPrecip
(hrs)(hrs)(hrs)(hrs)(hrs)(in)(in)(in)(in)(in)
10.900.015711
10.930.016022
10.970.016333
11.000.016644
11.030.017171
11.070.017920
11.100.018667
11.130.019413
11.170.020160
11.200.020907
11.230.021653
11.270.022400
11.300.023147
11.330.023893
11.370.024640
11.400.025387
11.430.026133
11.470.026880
11.500.027627
11.530.037261
11.570.055627
11.600.074045
11.630.092462
11.670.110880
11.700.129298
11.730.147716
11.770.169553
11.800.217353
11.830.268582
11.870.319812
11.900.371042
11.930.338609
11.970.221783
12.000.105194
12.030.046797
12.070.044240
12.100.042467
12.130.040693
12.170.038920
12.200.037147
12.230.035373
12.270.033600
12.300.031827
12.330.030053
12.370.028280
12.400.026506
12.430.024734
12.470.022960
12.500.021187
12.530.020100
12.570.019693
12.600.019289
12.630.018885
12.670.018480
12.700.018075
Time (hrs)
0 2 4 6 8 10 12 14 16 18 20 22 24
Pr
e
c
i
p
(
i
n
)
0
1
2
3
4
5
6
7
Pr
e
c
i
p
(
i
n
)
0
1
2
3
4
5
6
7
14
Hydrograph 25-yr Summary Project Name:
Hydrology Studio v 3.0.0.13 02-27-2020
Hyd.
No.
Hydrograph
Type
Hydrograph
Name
Peak
Flow
(cfs)
Time to
Peak
(hrs)
Hydrograph
Volume
(cuft)
Inflow
Hyd(s)
Maximum
Elevation
(ft)
Maximum
Storage
(cuft)
1NRCS RunoffPost-Dev15.4212.67118,927----
2NRCS RunoffPost-Dev43.3212.17179,988----
3Pond RouteDeveloped pond Count14.9812.57155,477224.0396,427
15
Hydrograph Report Project Name:
Hydrology Studio v 3.0.0.13 02-27-2020
Post-DevHyd. No. 1
Hydrograph Type= NRCS RunoffPeak Flow= 15.42 cfs
Storm Frequency= 25-yrTime to Peak= 12.67 hrs
Time Interval= 2 minRunoff Volume= 118,927 cuft
Drainage Area= 7.5 acCurve Number= 69
Tc Method= LagTime of Conc. (Tc)= 74.8 min
Basin Slope= 0.5 %Hydraulic Length= 1273 ft
Total Rainfall= 8.05 inDesign Storm= Type II
Storm Duration= 24 hrsShape Factor= 484
Time (hrs)
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26
Q
(
c
f
s
)
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
Qp = 15.42 cfs
16
Hydrograph Report Project Name:
Hydrology Studio v 3.0.0.13 02-27-2020
Post-DevHyd. No. 2
Hydrograph Type= NRCS RunoffPeak Flow= 43.32 cfs
Storm Frequency= 25-yrTime to Peak= 12.17 hrs
Time Interval= 2 minRunoff Volume= 179,988 cuft
Drainage Area= 7.5 acCurve Number= 87.95*
Tc Method= LagTime of Conc. (Tc)= 30.2 min
Basin Slope= 0.5 %Hydraulic Length= 855 ft
Total Rainfall= 8.05 inDesign Storm= Type II
Storm Duration= 24 hrsShape Factor= 484
* Composite CN Worksheet
AREA (ac)CNDESCRIPTION
2.669Undisturbed
4.998IMPERVIOUS
7.588 Weighted CN Method Employed
Time (hrs)
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
Q
(
c
f
s
)
0
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
34
36
38
40
42
44
46
48
Qp = 43.32 cfs
17
Hydrograph Report Project Name:
Hydrology Studio v 3.0.0.13 02-27-2020
Developed pond CountHyd. No. 3
Hydrograph Type= Pond RoutePeak Flow= 14.98 cfs
Storm Frequency= 25-yrTime to Peak= 12.57 hrs
Time Interval= 2 minHydrograph Volume= 155,477 cuft
Inflow Hydrograph= 2 -Post-DevMax. Elevation= 24.03 ft
Pond Name= Pre-Post PondMax. Storage= 96,427 cuft
Pond Routing by Storage Indication Method Center of mass detention time = 2.22 hrs
Post-Dev Developed pond Count
Time (hrs)
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95
Q
(
c
f
s
)
0
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
34
36
38
40
42
44
46
48
Qp = 14.98 cfs
18
Design Storm Report Custom Storm filename: 2017-1203first-attempt.cds
Hydrology Studio v 3.0.0.13 02-27-2020
Storm Distribution: NRCS/SCS -Type II
Total Rainfall Volume (in)Storm
Duration 1-yr2-yr3-yr5-yr10-yr 25-yr50-yr100-yr
24 hrs 0.004.500.005.807.008.059.0010.00
Incremental Rainfall Distribution, 25-yr
TimeTimeTimeTimeTimePrecipPrecipPrecipPrecipPrecip
(hrs)(hrs)(hrs)(hrs)(hrs)(in)(in)(in)(in)(in)
10.900.018068
10.930.018426
10.970.018783
11.000.019141
11.030.019747
11.070.020608
11.100.021467
11.130.022325
11.170.023184
11.200.024043
11.230.024901
11.270.025760
11.300.026618
11.330.027478
11.370.028336
11.400.029195
11.430.030053
11.470.030912
11.500.031771
11.530.042850
11.570.063971
11.600.085151
11.630.106332
11.670.127512
11.700.148693
11.730.169873
11.770.194985
11.800.249956
11.830.308870
11.870.367784
11.900.426698
11.930.389401
11.970.255050
12.000.120973
12.030.053816
12.070.050876
12.100.048837
12.130.046797
12.170.044758
12.200.042719
12.230.040679
12.270.038640
12.300.036601
12.330.034561
12.370.032522
12.400.030483
12.430.028443
12.470.026404
12.500.024364
12.530.023115
12.570.022647
12.600.022182
12.630.021717
12.670.021252
12.700.020787
Time (hrs)
0 2 4 6 8 10 12 14 16 18 20 22 24
Pr
e
c
i
p
(
i
n
)
0
1
2
3
4
5
6
7
8
9
Pr
e
c
i
p
(
i
n
)
0
1
2
3
4
5
6
7
8
9
19
Hydrograph 100-yr Summary Project Name:
Hydrology Studio v 3.0.0.13 02-27-2020
Hyd.
No.
Hydrograph
Type
Hydrograph
Name
Peak
Flow
(cfs)
Time to
Peak
(hrs)
Hydrograph
Volume
(cuft)
Inflow
Hyd(s)
Maximum
Elevation
(ft)
Maximum
Storage
(cuft)
1NRCS RunoffPost-Dev21.5012.67164,994----
2NRCS RunoffPost-Dev55.1512.17232,095----
3Pond RouteDeveloped pond Count30.1712.43207,475224.42110,534
20
Hydrograph Report Project Name:
Hydrology Studio v 3.0.0.13 02-27-2020
Post-DevHyd. No. 1
Hydrograph Type= NRCS RunoffPeak Flow= 21.50 cfs
Storm Frequency= 100-yrTime to Peak= 12.67 hrs
Time Interval= 2 minRunoff Volume= 164,994 cuft
Drainage Area= 7.5 acCurve Number= 69
Tc Method= LagTime of Conc. (Tc)= 74.8 min
Basin Slope= 0.5 %Hydraulic Length= 1273 ft
Total Rainfall= 10.00 inDesign Storm= Type II
Storm Duration= 24 hrsShape Factor= 484
Time (hrs)
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26
Q
(
c
f
s
)
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
Qp = 21.50 cfs
21
Hydrograph Report Project Name:
Hydrology Studio v 3.0.0.13 02-27-2020
Post-DevHyd. No. 2
Hydrograph Type= NRCS RunoffPeak Flow= 55.15 cfs
Storm Frequency= 100-yrTime to Peak= 12.17 hrs
Time Interval= 2 minRunoff Volume= 232,095 cuft
Drainage Area= 7.5 acCurve Number= 87.95*
Tc Method= LagTime of Conc. (Tc)= 30.2 min
Basin Slope= 0.5 %Hydraulic Length= 855 ft
Total Rainfall= 10.00 inDesign Storm= Type II
Storm Duration= 24 hrsShape Factor= 484
* Composite CN Worksheet
AREA (ac)CNDESCRIPTION
2.669Undisturbed
4.998IMPERVIOUS
7.588 Weighted CN Method Employed
Time (hrs)
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
Q
(
c
f
s
)
0
5
10
15
20
25
30
35
40
45
50
55
60
Qp = 55.15 cfs
22
Hydrograph Report Project Name:
Hydrology Studio v 3.0.0.13 02-27-2020
Developed pond CountHyd. No. 3
Hydrograph Type= Pond RoutePeak Flow= 30.17 cfs
Storm Frequency= 100-yrTime to Peak= 12.43 hrs
Time Interval= 2 minHydrograph Volume= 207,475 cuft
Inflow Hydrograph= 2 -Post-DevMax. Elevation= 24.42 ft
Pond Name= Pre-Post PondMax. Storage= 110,534 cuft
Pond Routing by Storage Indication Method Center of mass detention time = 1.82 hrs
Post-Dev Developed pond Count
Time (hrs)
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29
Q
(
c
f
s
)
0
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
34
36
38
40
42
44
46
48
50
52
54
56
58
60
62
Qp = 30.17 cfs
23
Design Storm Report Custom Storm filename: 2017-1203first-attempt.cds
Hydrology Studio v 3.0.0.13 02-27-2020
Storm Distribution: NRCS/SCS -Type II
Total Rainfall Volume (in)Storm
Duration 1-yr2-yr3-yr5-yr10-yr25-yr50-yr 100-yr
24 hrs 0.004.500.005.807.008.059.0010.00
Incremental Rainfall Distribution, 100-yr
TimeTimeTimeTimeTimePrecipPrecipPrecipPrecipPrecip
(hrs)(hrs)(hrs)(hrs)(hrs)(in)(in)(in)(in)(in)
10.900.022444
10.930.022889
10.970.023333
11.000.023778
11.030.024530
11.070.025600
11.100.026667
11.130.027733
11.170.028800
11.200.029867
11.230.030933
11.270.032000
11.300.033067
11.330.034133
11.370.035200
11.400.036267
11.430.037333
11.470.038400
11.500.039467
11.530.053231
11.570.079467
11.600.105778
11.630.132089
11.670.158400
11.700.184711
11.730.211023
11.770.242218
11.800.310504
11.830.383689
11.870.456874
11.900.530059
11.930.483727
11.970.316832
12.000.150277
12.030.066853
12.070.063200
12.100.060667
12.130.058133
12.170.055600
12.200.053067
12.230.050533
12.270.048000
12.300.045467
12.330.042933
12.370.040400
12.400.037867
12.430.035334
12.470.032800
12.500.030267
12.530.028714
12.570.028133
12.600.027555
12.630.026978
12.670.026400
12.700.025822
Time (hrs)
0 2 4 6 8 10 12 14 16 18 20 22 24
Pr
e
c
i
p
(
i
n
)
0
1
2
3
4
5
6
7
8
9
10
Pr
e
c
i
p
(
i
n
)
0
1
2
3
4
5
6
7
8
9
10
24
Table of Contents Project Name:
Hydrology Studio v 3.0.0.13 02-27-2020
100 -Year
Hydrograph Summary 1..................................................................................................................................
Hydrograph Reports
Hydrograph No. 1, NRCS Runoff, Post-Dev2............................................................................................
Hydrograph No. 2, NRCS Runoff, Post-Dev3............................................................................................
Hydrograph No. 3, Pond Route, Developed pond Count4............................................................................
Detention Pond Reports -Pre-Post Pond5...................................................................................
Design Storm Report -NRCS/SCS -Type II9................................................................................
Hydrograph 100-yr Summary Project Name:
Hydrology Studio v 3.0.0.13 02-27-2020
Hyd.
No.
Hydrograph
Type
Hydrograph
Name
Peak
Flow
(cfs)
Time to
Peak
(hrs)
Hydrograph
Volume
(cuft)
Inflow
Hyd(s)
Maximum
Elevation
(ft)
Maximum
Storage
(cuft)
1NRCS RunoffPost-Dev21.5012.67164,994----
2NRCS RunoffPost-Dev55.1512.17232,095----
3Pond RouteDeveloped pond Count27.9512.47118,566224.92128,776
1
Hydrograph Report Project Name:
Hydrology Studio v 3.0.0.13 02-27-2020
Post-DevHyd. No. 1
Hydrograph Type= NRCS RunoffPeak Flow= 21.50 cfs
Storm Frequency= 100-yrTime to Peak= 12.67 hrs
Time Interval= 2 minRunoff Volume= 164,994 cuft
Drainage Area= 7.5 acCurve Number= 69
Tc Method= LagTime of Conc. (Tc)= 74.8 min
Basin Slope= 0.5 %Hydraulic Length= 1273 ft
Total Rainfall= 10.00 inDesign Storm= Type II
Storm Duration= 24 hrsShape Factor= 484
Time (hrs)
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26
Q
(
c
f
s
)
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
Qp = 21.50 cfs
2
Hydrograph Report Project Name:
Hydrology Studio v 3.0.0.13 02-27-2020
Post-DevHyd. No. 2
Hydrograph Type= NRCS RunoffPeak Flow= 55.15 cfs
Storm Frequency= 100-yrTime to Peak= 12.17 hrs
Time Interval= 2 minRunoff Volume= 232,095 cuft
Drainage Area= 7.5 acCurve Number= 87.95*
Tc Method= LagTime of Conc. (Tc)= 30.2 min
Basin Slope= 0.5 %Hydraulic Length= 855 ft
Total Rainfall= 10.00 inDesign Storm= Type II
Storm Duration= 24 hrsShape Factor= 484
* Composite CN Worksheet
AREA (ac)CNDESCRIPTION
2.669Undisturbed
4.998IMPERVIOUS
7.588 Weighted CN Method Employed
Time (hrs)
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
Q
(
c
f
s
)
0
5
10
15
20
25
30
35
40
45
50
55
60
Qp = 55.15 cfs
3
Hydrograph Report Project Name:
Hydrology Studio v 3.0.0.13 02-27-2020
Developed pond CountHyd. No. 3
Hydrograph Type= Pond RoutePeak Flow= 27.95 cfs
Storm Frequency= 100-yrTime to Peak= 12.47 hrs
Time Interval= 2 minHydrograph Volume= 118,566 cuft
Inflow Hydrograph= 2 -Post-DevMax. Elevation= 24.92 ft
Pond Name= Pre-Post PondMax. Storage= 128,776 cuft
Pond Routing by Storage Indication Method Center of mass detention time = 2.16 hrs
Post-Dev Developed pond Count
Time (hrs)
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
Q
(
c
f
s
)
0
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
34
36
38
40
42
44
46
48
50
52
54
56
58
60
62
Qp = 27.95 cfs
4
Pond Report Project Name:
Hydrology Studio v 3.0.0.13 02-27-2020
Pre-Post PondStage-Storage
DescriptionInput
Stage / Storage Table
Stage
(ft)
Elevation
(ft)
Contour Area
(sqft)
Incr. Storage
(cuft)
Total Storage
(cuft)
User Defined Contours
Bottom Elevation, ft
Voids (%)
Volume Calc
21.00
100.00
None
0.0021.0028,5100.0000.000
1.0022.0030,66629,58829,588
2.0023.0032,87831,77261,360
3.0024.0035,14734,01395,373
4.0025.0037,47336,310131,683
Contours Top of Pond
Total Storage (cuft)
0 20000 40000 60000 80000 100000 120000 140000
El
e
v
(
f
t
)
21
22
23
24
25
St
a
g
e
(
f
t
)
0
1
2
3
4
Stage-Storage
5
Pond Report Project Name:
Hydrology Studio v 3.0.0.13 02-27-2020
Pre-Post PondStage-Discharge
Culvert / Orifices
Rise, in
Span, in
No. Barrels
Invert Elevation, ft
Orifice Coefficient, Co
Length, ft
Barrel Slope, %
N-Value, n
Culvert Orifices
1*23
302
302
11
20.5021.00
0.600.60
50
.5
0.013
Orifice Plate
Orifice Dia, in
No. Orifices
Invert Elevation, ft
Height, ft
Orifice Coefficient, Co
Weirs
Shape / Type
Crest Elevation, ft
Crest Length, ft
Angle, deg
Weir Coefficient, Cw
Riser*Weirs
1*23
Box RectangularBroad Crested
2422.724.5
16330
18.4 (3:1)
3.33.33.3
Ancillary
Exfiltration, in/hr
*Routes through Culvert.
Top of Pond Broad Crested Total Q
Discharge (cfs)
024681012141618202224262830323436
El
e
v
(
f
t
)
21
22
23
24
25
St
a
g
e
(
f
t
)
0
1
2
3
4Stage-Discharge
6
Pond Report Project Name:
Hydrology Studio v 3.0.0.13 02-27-2020
Pre-Post PondStage-Storage-Discharge Summary
Stage
(ft)
Elev.
(ft)
Storage
(cuft)
Culvert
(cfs)
Orifices, cfs
123
Riser
(cfs)
Weirs, cfs
123
Pf Riser
(cfs)
Exfil
(cfs)
User
(cfs)
Total
(cfs)
0.0021.000.0000.000 0.0000.000 0.000 0.000 0.000
1.0022.0029,5880.000 0.0000.000 0.000 0.000 0.000
2.0023.0061,3600.000 0.0000.000 0.000 0.000 0.000
3.0024.0095,3730.000 0.0000.000 0.000 0.000 0.000
4.0025.00131,6830.000 0.0000.000 0.000 36.40 36.40
Suffix key: ic = inlet control, oc = outlet control, s = submerged weir 7
Pond Report Project Name:
Hydrology Studio v 3.0.0.13 02-27-2020
Pre-Post PondPond Drawdown
St
a
g
e
v
s
.
D
r
a
i
n
T
i
m
e
Dr
a
i
n
T
i
m
e
(
H
r
s
)
0
0
.
0
5
0
.
1
0
.
1
5
0
.
2
0
.
2
5
0
.
3
0
.
3
5
0
.
4
0
.
4
5
0
.
5
0
.
5
5
0
.
6
0
.
6
5
0
.
7
0
.
7
5
0
.
8
0
.
8
5
0
.
9
0
.
9
5
Elev (ft)
2122232425
Stage (ft)
01234
Pr
e
-
P
o
s
t
P
o
n
d
-
D
r
a
i
n
T
i
m
e
8
Design Storm Report Custom Storm filename: 2017-1203first-attempt.cds
Hydrology Studio v 3.0.0.13 02-27-2020
Storm Distribution: NRCS/SCS -Type II
Total Rainfall Volume (in)Storm
Duration 1-yr2-yr3-yr5-yr10-yr25-yr50-yr 100-yr
24 hrs 0.004.500.005.807.008.059.0010.00
Incremental Rainfall Distribution, 100-yr
TimeTimeTimeTimeTimePrecipPrecipPrecipPrecipPrecip
(hrs)(hrs)(hrs)(hrs)(hrs)(in)(in)(in)(in)(in)
10.900.022444
10.930.022889
10.970.023333
11.000.023778
11.030.024530
11.070.025600
11.100.026667
11.130.027733
11.170.028800
11.200.029867
11.230.030933
11.270.032000
11.300.033067
11.330.034133
11.370.035200
11.400.036267
11.430.037333
11.470.038400
11.500.039467
11.530.053231
11.570.079467
11.600.105778
11.630.132089
11.670.158400
11.700.184711
11.730.211023
11.770.242218
11.800.310504
11.830.383689
11.870.456874
11.900.530059
11.930.483727
11.970.316832
12.000.150277
12.030.066853
12.070.063200
12.100.060667
12.130.058133
12.170.055600
12.200.053067
12.230.050533
12.270.048000
12.300.045467
12.330.042933
12.370.040400
12.400.037867
12.430.035334
12.470.032800
12.500.030267
12.530.028714
12.570.028133
12.600.027555
12.630.026978
12.670.026400
12.700.025822
Time (hrs)
0 2 4 6 8 10 12 14 16 18 20 22 24
Pr
e
c
i
p
(
i
n
)
0
1
2
3
4
5
6
7
8
9
10
Pr
e
c
i
p
(
i
n
)
0
1
2
3
4
5
6
7
8
9
10
9