Southstone - 2018-01-31 Southstone SIA

SOUTHSTONE
Stormwater Impact Analysis and Final Design of Stormwater Management Facilities / November 2017
STORMWATER IMPACT ANALYSIS
creating experiences through experience 3436 Toringdon Way, Suite 110, Charlotte, NC 28277 / 704. 527. 0800
GENERAL DESCRIPTION
The proposed Southstone development is located along Stevens Mill Road in Union County, North
Carolina. The proposed development on this site will consist of 165 single-family homes and supporting
street, parking, utility, and stormwater management improvements.
The proposed development is located within the Yadkin River Basin with stormwater runoff from the
site draining to an unnamed tributary to Goose Creek. Per Town of Stallings regulations, stormwater
management on this site shall meet the stormwater performance standards for the Goose Creek District
as outlined in the Town of Stallings Development Ordinance. These are as follows:
§ 52.38 DEVELOPMENT STANDARDS FOR GOOSE CREEK DISTRICT.
(A)Development standards for low density projects. Any drainage area within a project is
considered low density when said drainage area has less than 10% built upon area. Such low-
density projects shall comply with each of the following standards.
(1)Storm water quality treatment volume. Storm water quality treatment systems shall treat
the difference in the storm water runoff from pre-development and post-development
conditions for the one-year, 24-hour storm.
(2)Storm water quality treatment. Storm water quality treatment systems shall be designed to
have a minimum of 85% average annual removal of total suspended solids from the storm
water quality treatment volume.
(3)Storm water treatment system design. General engineering design criteria for all projects
shall be in accordance with 15A NCAC 2H.1008(c), as explained in the Design Manual.
(4)Stream buffers. Undisturbed buffers are required for perennial and intermittent streams as
well as the ponds, lakes, and reservoirs (excluding wetlands) with hydrologic connections to
such streams. The buffer width is 200 feet wide if located within the 100-year floodplain or
100 feet wide if located outside the 100-year floodplain. Buffer widths shall be measured
horizontally on a line perpendicular to the surface water, landward from the top of the
bank on each side of the stream. Development within this watershed must follow the
requirements of the Site Specific Water Quality Management Plan for the Goose Creek
Watershed.
(5)Storm water volume control. Storm water treatment systems shall be installed to control
the difference in the storm water runoff from pre-development and post-development
conditions for the one-year, 24-hour storm at a rate equal or less than the pre-
development discharge rate. Runoff volume drawdown time shall be a minimum of 24
hours, but not more than 120 hours.
STORMWATER IMPACT ANALYSIS
creating experiences through experience 2 of 3
(B)Development standards for high density projects. Any drainage area within a project is
considered high density when said drainage area has greater than or equal to 10% built upon
area. Such high-density projects shall implement storm water treatment systems that comply
with the low density standards and the following additional standards.
(1)Storm water peak control. Peak control shall be installed for the 10-year and 25-year, six-
hour storms. The emergency overflow and outlets work for any pond or wetland discharge
with a minimum recurrence frequency as specified in the Design Manual. For detention
basins, the temporary storage capacity shall be restored within 72 hours. Requirements of
the Dam Safety Act shall be met when applicable.
In order to meet the above applicable standards, six stormwater management facilities (SWMF) were
proposed. This report serves as the stormwater impact analysis for the proposed development and
includes final design calculation for these facilities.
CALCULATION METHODOLOGY
>Rainfall data for the analysis was taken from the City of Charlotte BMP Design Manual. Please
reference the precipitation information section within this report for additional information.
>Using maps contained within the Union County Soil Survey, the on-site soils were determined to
be hydrologic soil group (HSG) ‘B’, ‘C’, and ‘D’ soils. Since the method chosen to compute post-
development peak flow rates and runoff volumes is dependent upon the soil type, care was
taken when selecting the appropriate Soil Conservation Service Curve Number (SCS CN). A
composite SCS CN was computed for each pre- and post-development sub-basin. For example,
Subbasin #1 in the pre-development analysis consists of approximately 88% HSG ‘B’ soils and
12% HSG ‘C’ soils. Therefore, for the open area cover condition, the composite SCS CN is
computed as follows (assuming good condition):
Composite Open SCS CN = (88%x 61)+ (12%x 74) = 63
>A composite SCS Curve Number was calculated for both the pre- and post-development
condition for each subbasin using SCS curve numbers and land cover conditions. Land cover
conditions for the pre-development condition were taken from available survey and GIS
information. Land cover conditions for the post-development condition were taken from the
proposed development plan.
>The time of concentration was calculated using SCS TR-55 (Segmental Approach, 1986). The Tc
flow path was divided into three segments: overland flow, concentrated flow, and channel
flow. The travel time was then computed for each segment, from which the overall time of
concentration was determined by taking the sum of each segmental time.
STORMWATER IMPACT ANALYSIS
creating experiences through experience 3 of 3
>PondPack Version V8i was used in determining the pre- & post-development peak flow rates for
the 2-, 10-, 25-, and 100-year storm events, as well as routing calculations for the proposed
stormwater management facilities.
>The proposed stormwater management facilities are designed in accordance with the Minimum
Design Criteria (MDC) standards set forth in the NC DEMLR Stormwater Design Manual.
DISCUSSION OF RESULTS
Peak Runoff Control Requirements:
As shown in the Summary of Results provided, the proposed stormwater management facilities provide
the necessary on-site peak runoff control such that there are no predicted increases in the 2-, 10-, 25-,
and 100-year storm events at each of the studied Points of Analyses (POA).
Water Quality Requirements:
The proposed stormwater management facilities provide the necessary runoff treatment for the
difference in volume. difference in the storm water runoff from pre-development and post-
development conditions for the one-year, 24-hour storm Please note that SWMF ‘C’ is sized to
accommodate the future amenity area.
CONCLUSION
If the development on this tract is built as proposed within this report, then the requirements set forth
in Town of Stalling Development Ordinance will be met. However, modifications to the proposed
development may require that this analysis be revised. Some modifications that would require this
analysis to be revised include:
>The proposed site impervious surface exceeds the amount accounted for in this report.
>The post-development watershed breaks change significantly from those used to prepare this
report.
The above modifications may result in the assumptions within this report becoming invalid. The
computations within this report will need to be revisited if any of the above conditions become
apparent as development of the proposed site moves forward.
8 DESIGN OF STORMWATER
MANAGEMENT FACILITY B
6 POST-DEVELOPMENT HYDROLOGIC
CALCULATIONS
7 DESIGN OF STORMWATER
MANAGEMENT FACILITY A
1 SUMMARY OF RESULTS
2 MISCELLANEOUS SITE INFORMATION
5 PRE-DEVELOPMENT HYDROLOGIC
CALCULATIONS
3 WATERSHED SOILS INFORMATION
4 PRECIPITATION DATA
12 DESIGN OF STORMWATER
MANAGEMENT FACILITY F
9 DESIGN OF STORMWATER
MANAGEMENT FACILITY C
10 DESIGN OF STORMWATER
MANAGEMENT FACILITY D
11 DESIGN OF STORMWATER
MANAGEMENT FACILITY E
SOUTHSTONE
TAC-17000
SUMMARY OF RESULTS
Project Name: Southstone Date:1/18/2018
Project Number:TAC-17000 Calculated By: J. Aldridge, PE
RELEASE RATE MANAGEMENT RESULTS
Pre-Dev Post-Dev
Return Period [cfs][cfs]% Increase
1-Year 24-Hour 123 102 -17%
2-Year 6-Hour 127 106 -17%
10-Year 6-Hour 409 359 -12%
25-Year 6-Hour 563 497 -12%
100-Year 6-Hour 800 717 -10%
Pre-Dev Post-Dev
Return Period [cfs][cfs]% Increase
1-Year 24-Hour 114 97 -15%
2-Year 6-Hour 117 100 -15%
10-Year 6-Hour 368 334 -9%
25-Year 6-Hour 501 463 -8%
100-Year 6-Hour 709 662 -7%
Pre-Dev Post-Dev
Return Period [cfs][cfs]% Increase
1-Year 24-Hour 88 86 -2%
2-Year 6-Hour 90 89 -1%
10-Year 6-Hour 277 274 -1%
25-Year 6-Hour 378 373 -1%
100-Year 6-Hour 530 523 -1%
Pre-Dev Post-Dev
Return Period [cfs][cfs]% Increase
1-Year 24-Hour 9 7 -22%
2-Year 6-Hour 8 7 -13%
10-Year 6-Hour 34 30 -12%
25-Year 6-Hour 49 42 -14%
100-Year 6-Hour 73 72 -1%
SUMMARY OF RESULTS
POINT OF ANALYSIS #1
POINT OF ANALYSIS #2
POINT OF ANALYSIS #4
POINT OF ANALYSIS #3
Project Name: Southstone Date:1/18/2018
Project Number: TAC-17000 Calculated By: J. Aldridge, PE
STORMWATER MANAGEMENT FACILITY 'A' SUMMARY
Design Drainage Area =10.18 acres
Design Impervious Area =2.95 acres
% Impervious =28.99%
1" Water Quality Volume =11,488 cf
1-Year Treatment Volume =23,750 cf
Treatment Vol Ponding Depth =14.97 in
Top of Dam =622.50 ft
NWSE =618.50 ft
Siphon Diameter =2.50 in
Siphon Elevation =618.50 ft
Number of Orifices =2
Orifice Diameter =6.00 in
Orifice Bottom Elevation =619.80 ft
Riser Size =4' x 4'
Riser Crest =621.30 ft
Barrel Diameter =24 in
# of Barrels =1
Upstream Invert =618.00 ft
Downstream Invert =617.00 ft
Length =27 ft
Slope =0.0370 ft/ft
STORMWATER MANAGEMENT FACILITY 'A' ROUTING RESULTS
Inflow Outflow Max WSE Freeboard
Return Period [cfs][cfs][ft][ft]
1-Year 24-Hour 8.52 0.14 619.37 3.13
2-Year 6-Hour 9.78 0.14 619.32 3.18
10-Year 6-Hour 28.17 1.31 620.39 2.11
25-Year 6-Hour 37.93 1.95 620.87 1.63
100-Year 6-Hour 53.66 5.46 621.45 1.05
SUMMARY OF RESULTS
Project Name: Southstone Date:1/18/2018
Project Number: TAC-17000 Calculated By: J. Aldridge, PE
STORMWATER MANAGEMENT FACILITY 'B' SUMMARY
Design Drainage Area =17.49 acres
Design Impervious Area =6.59 acres
% Impervious =37.68%
Water Quality Volume =24,704 cf
1-Year Treatment Volume =37,472 cf
Treatment Vol Ponding Depth =15.18 in
Top of Dam =633.00 ft
NWSE =628.00 ft
Siphon Diameter =3.25 in
Siphon Elevation =628.00 ft
Number of Orifices =2
Orifice Size =2' x 0.5'
Orifice Bottom Elevation =629.40 ft
Riser Size =4' x 4'
Riser Crest =631.50 ft
Barrel Diameter =24 in
# of Barrels =1
Upstream Invert =625.50 ft
Downstream Invert =625.00 ft
Length =57 ft
Slope =0.0088 ft/ft
STORMWATER MANAGEMENT FACILITY 'B' ROUTING RESULTS
Inflow Outflow Max WSE Freeboard
Return Period [cfs][cfs][ft][ft]
1-Year 24-Hour 22.35 0.31 629.38 3.62
2-Year 6-Hour 26.89 0.30 629.31 3.69
10-Year 6-Hour 63.65 7.29 630.16 2.84
25-Year 6-Hour 82.26 10.30 630.70 2.30
100-Year 6-Hour 111.80 14.63 631.56 1.44
SUMMARY OF RESULTS
Project Name: Southstone Date:1/18/2018
Project Number: TAC-17000 Calculated By: J. Aldridge, PE
STORMWATER MANAGEMENT FACILITY 'C' SUMMARY
Design Drainage Area =9.28 acres
Design Impervious Area =3.82 acres
% Impervious =41.20%
Water Quality Volume =14,174 cf
1-Year Treatment Volume =20,227 cf
Treatment Vol Ponding Depth =14.54 in
Top of Dam =625.00 ft
NWSE =620.00 ft
Siphon Diameter =2.25 in
Siphon Elevation =620.00 ft
Number of Orifices =2
Orifice Diameter =6.00 in
Orifice Bottom Elevation =621.30 ft
Riser Size =4' x 4'
Riser Crest =623.00 ft
Barrel Diameter =24 in
# of Barrels =1
Upstream Invert =616.50 ft
Downstream Invert =615.00 ft
Length =72 ft
Slope =0.0208 ft/ft
STORMWATER MANAGEMENT FACILITY 'C' ROUTING RESULTS
Inflow Outflow Max WSE Freeboard
Return Period [cfs][cfs][ft][ft]
1-Year 24-Hour 18.08 0.55 621.60 3.40
2-Year 6-Hour 23.21 0.70 621.66 3.34
10-Year 6-Hour 44.39 2.48 622.97 2.03
25-Year 6-Hour 54.76 8.76 623.25 1.75
100-Year 6-Hour 71.00 22.88 623.56 1.44
SUMMARY OF RESULTS
Project Name: Southstone Date:1/18/2018
Project Number: TAC-17000 Calculated By: J. Aldridge, PE
STORMWATER MANAGEMENT FACILITY 'D' SUMMARY
Design Drainage Area =15.31 acres
Design Impervious Area =4.17 acres
% Impervious =27.25%
Water Quality Volume =16,413 cf
1-Year Treatment Volume =40,453 cf
Treatment Vol Ponding Depth =15.45 in
Top of Dam =634.00 ft
NWSE =628.00 ft
Siphon Diameter =3.25 in
Siphon Elevation =628.00 ft
Number of Orifices =3
Orifice Size =2' x 0.5'
Orifice Bottom Elevation =629.40 ft
Riser Size =4' x 4'
Riser Crest =630.40 ft
Barrel Diameter =24 in
# of Barrels =1
Upstream Invert =623.50 ft
Downstream Invert =620.00 ft
Length =70 ft
Slope =0.0500 ft/ft
STORMWATER MANAGEMENT FACILITY 'D' ROUTING RESULTS
Inflow Outflow Max WSE Freeboard
Return Period [cfs][cfs][ft][ft]
1-Year 24-Hour 26.72 0.63 629.42 4.58
2-Year 6-Hour 33.77 0.91 629.44 4.56
10-Year 6-Hour 68.18 10.39 630.13 3.87
25-Year 6-Hour 85.16 16.59 630.54 3.46
100-Year 6-Hour 111.82 35.32 630.97 3.03
SUMMARY OF RESULTS
Project Name: Southstone Date:1/18/2018
Project Number: TAC-17000 Calculated By: J. Aldridge, PE
STORMWATER MANAGEMENT FACILITY 'E' SUMMARY
Design Drainage Area =17.24 acres
Design Impervious Area =6.18 acres
% Impervious =35.87%
Water Quality Volume =23,329 cf
1-Year Treatment Volume =20,227 cf
Treatment Vol Ponding Depth =14.90 in
Top of Dam =620.00 ft
NWSE =614.00 ft
Siphon Diameter =2.50 in
Siphon Elevation =614.00 ft
Number of Orifices =2
Orifice Diameter =6.00 in
Orifice Bottom Elevation =615.30 ft
Riser Size =4' x 4'
Riser Crest =617.50 ft
Barrel Diameter =24 in
# of Barrels =1
Upstream Invert =613.50 ft
Downstream Invert =613.00 ft
Length =37 ft
Slope =0.0135 ft/ft
STORMWATER MANAGEMENT FACILITY 'E' ROUTING RESULTS
Inflow Outflow Max WSE Freeboard
Return Period [cfs][cfs][ft][ft]
1-Year 24-Hour 28.40 1.34 615.89 4.11
2-Year 6-Hour 35.58 1.52 616.02 3.98
10-Year 6-Hour 73.94 9.18 617.75 2.25
25-Year 6-Hour 92.94 22.55 618.06 1.94
100-Year 6-Hour 122.84 31.92 618.84 1.16
SUMMARY OF RESULTS
Project Name: Southstone Date:1/18/2018
Project Number: TAC-17000 Calculated By: J. Aldridge, PE
STORMWATER MANAGEMENT FACILITY 'F' SUMMARY
Design Drainage Area =13.60 acres
Design Impervious Area =2.87 acres
% Impervious =21.09%
Water Quality Volume =11,836 cf
1-Year Treatment Volume =11,248 cf
Treatment Vol Ponding Depth =11.42 in
Top of Dam =643.00 ft
NWSE =639.00 ft
Siphon Diameter =1.75 in
Siphon Elevation =639.00 ft
Number of Orifices =2
Orifice Size =2' x 0.5'in
Orifice Bottom Elevation =640.00 ft
Riser Size =4' x 4'
Riser Crest =641.50 ft
Barrel Diameter =24 in
# of Barrels =1
Upstream Invert =636.50 ft
Downstream Invert =636.00 ft
Length =38 ft
Slope =0.0132 ft/ft
STORMWATER MANAGEMENT FACILITY 'F' ROUTING RESULTS
Inflow Outflow Max WSE Freeboard
Return Period [cfs][cfs][ft][ft]
1-Year 24-Hour 9.04 0.50 640.04 2.96
2-Year 6-Hour 9.60 0.72 640.07 2.93
10-Year 6-Hour 32.92 7.90 640.91 2.09
25-Year 6-Hour 45.70 11.24 641.52 1.48
100-Year 6-Hour 66.49 28.39 642.04 0.96
SUMMARY OF RESULTS
SOUTHSTONE
TAC-17000
MISCELLANEOUS SITE INFORMATION
Esri, HERE, DeLorme, MapmyIndia, © OpenStreetMap contributors
0 600 1,200300Feet1 inch = 600 feet
¯SOUTHSTONE
SITE AERIAL MAPPROJECT #: TAC-17000UNION COUNTY, NORTH CAROLINA
Copyright:© 2013 National Geographic Society, i-cubed
0 2,000 4,0001,000 Feet1 inch = 2,000 feet
¯SOUTHSTONE
USGS TOPO MAPPROJECT #: TAC-17000UNION COUNTY, NORTH CAROLINA
Legend
Cross-Sections
Base Flood Elevations
Flood Hazard Zones
1% Annual Chance Flood
Regulatory Floodway
Special Floodway
Area of Undetermined Flood Hazard
0.2% Annual Chance Flood
Future Conditions 1% Annual ChanceFlood Hazard
Area with Reduced Risk Due to Levee
LOMRs
Effective
Map Panels
Digital Data
Unmodernized Maps
Unmapped
USGS The National Map: Orthoimagery
National Flood H azard Layer FIR Mette
0 500 1,000 1,500 2,000250Feet
Ü80°37'42.53"W 35°8'23.42"N 80°37'3.56"W 35°7'52.81"N Date: 9/1/2017 Time: 11:53:29 AM
This map complies with FEMA’s standards for the use ofdigital flood maps. The flood hazard information isderived directly from the authoritative NFHL web servicesprovided by FEMA. The base map shown complies withFEMA’s base map accuracy standards.
The NFHL is a living database, updated daily, and thismap represents a snapshot of information at a specifictime.
Flood risks are dynamic and can change frequently due toa variety of factors, including weather patterns, erosion,and new development. FEMA flood maps are continuallyupdated through a variety of processes. Users shouldalways verify through the Map Service Center(http://msc.fema.gov) or the Community Map Repositorythat they have the current effective information.
NFHL maps should not be created for unmapped orunmodernized areas.
Legend
Cross-Sections
Base Flood Elevations
Flood Hazard Zones
1% Annual Chance Flood
Regulatory Floodway
Special Floodway
Area of Undetermined Flood Hazard
0.2% Annual C hance Flood
Future C onditions 1% Annual ChanceFlood H azard
Area with R educed Risk Due to Levee
LO MRs
Effective
Map Panels
Digital Data
Unmodernized Maps
Unmapped
USGS The National Map: Orthoimagery
National Flood Hazard Layer FIRMette
0 500 1,000 1,500 2,000250Feet
Ü80°37'39.70"W 35°8'1.96"N 80°37'0.74"W 35°7'31.34"N Date: 9/1/2017 Tim e: 11:57:16 AM
This map complies with FEMA’s standards for the use ofdigital flood maps. The flood hazard information isderived directly from the authoritative NFHL web servicesprovided by FEMA. The base map shown complies withFEMA’s base map accuracy standards.
The NFHL is a living database, updated daily, and thismap represents a snapshot of information at a specifictime.
Flood risks are dynamic and can change frequently due toa variety of factors, including weather patterns, erosion,and new development. FEMA flood maps are continuallyupdated through a variety of processes. Users shouldalways verify through the Map Service Center(http://msc.fema.gov) or the Community Map Repositorythat they have the current effective information.
NFH L maps should not be created for unmapped orunmodernized areas.
SOUTHSTONE
TAC-17000
WATERSHED SOILS INFORMATION
Hydrologic Soil Group—Union County, North Carolina
(Property Line)
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
3/13/2017
Page 1 of 43887200388730038874003887500388760038877003887800388790038880003888100388820038883003888400388850038872003887300388740038875003887600388770038878003887900388800038881003888200388830038884003888500534000534100534200534300534400534500534600534700534800534900
534000 534100 534200 534300 534400 534500 534600 534700 534800 534900
35° 8' 20'' N 80° 37' 38'' W35° 8' 20'' N80° 36' 57'' W35° 7' 36'' N
80° 37' 38'' W35° 7' 36'' N
80° 36' 57'' WN
Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 17N WGS84
0 300 600 1200 1800
Feet
0 50 100 200 300
Meters
Map Scale: 1:6,610 if printed on A portrait (8.5" x 11") sheet.
Soil Map may not be valid at this scale.
MAP LEGEND MAP INFORMATION
Area of Interest (AOI)
Area of Interest (AOI)
Soils
Soil Rating Polygons
A
A/D
B
B/D
C
C/D
D
Not rated or not available
Soil Rating Lines
A
A/D
B
B/D
C
C/D
D
Not rated or not available
Soil Rating Points
A
A/D
B
B/D
C
C/D
D
Not rated or not available
Water Features
Streams and Canals
Transportation
Rails
Interstate Highways
US Routes
Major Roads
Local Roads
Background
Aerial Photography
The soil surveys that comprise your AOI were mapped at
1:24,000.
Warning: Soil Map may not be valid at this scale.
Enlargement of maps beyond the scale of mapping can cause
misunderstanding of the detail of mapping and accuracy of soil
line placement. The maps do not show the small areas of
contrasting soils that could have been shown at a more detailed
scale.
Please rely on the bar scale on each map sheet for map
measurements.
Source of Map: Natural Resources Conservation Service
Web Soil Survey URL:
Coordinate System: Web Mercator (EPSG:3857)
Maps from the Web Soil Survey are based on the Web Mercator
projection, which preserves direction and shape but distorts
distance and area. A projection that preserves area, such as the
Albers equal-area conic projection, should be used if more
accurate calculations of distance or area are required.
This product is generated from the USDA-NRCS certified data as
of the version date(s) listed below.
Soil Survey Area: Union County, North Carolina
Survey Area Data: Version 16, Sep 20, 2016
Soil map units are labeled (as space allows) for map scales
1:50,000 or larger.
Date(s) aerial images were photographed: Feb 11, 2011—Feb
13, 2011
The orthophoto or other base map on which the soil lines were
compiled and digitized probably differs from the background
imagery displayed on these maps. As a result, some minor
shifting of map unit boundaries may be evident.
Hydrologic Soil Group—Union County, North Carolina
(Property Line)
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
3/13/2017
Page 2 of 4
Hydrologic Soil Group
Hydrologic Soil Group— Summary by Map Unit — Union County, North Carolina (NC179)
Map unit symbol Map unit name Rating Acres in AOI Percent of AOI
BaB Badin channery silt
loam, 2 to 8 percent
slopes
C 10.8 12.2%
CmB Cid channery silt loam, 1
to 5 percent slopes
D 7.1 8.0%
GsB Goldston-Badin
complex, 2 to 8
percent slopes
D 12.2 13.9%
ScA Secrest-Cid complex, 0
to 3 percent slopes
C 19.0 21.6%
TaB Tarrus gravelly silt loam,
2 to 8 percent slopes
B 38.6 43.7%
TuB Tarrus-Urban land
complex, 2 to 8
percent slopes
B 0.5 0.5%
Totals for Area of Interest 88.1 100.0%
Hydrologic Soil Group—Union County, North Carolina Property Line
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
3/13/2017
Page 3 of 4
Description
Hydrologic soil groups are based on estimates of runoff potential. Soils are
assigned to one of four groups according to the rate of water infiltration when the
soils are not protected by vegetation, are thoroughly wet, and receive
precipitation from long-duration storms.
The soils in the United States are assigned to four groups (A, B, C, and D) and
three dual classes (A/D, B/D, and C/D). The groups are defined as follows:
Group A. Soils having a high infiltration rate (low runoff potential) when
thoroughly wet. These consist mainly of deep, well drained to excessively
drained sands or gravelly sands. These soils have a high rate of water
transmission.
Group B. Soils having a moderate infiltration rate when thoroughly wet. These
consist chiefly of moderately deep or deep, moderately well drained or well
drained soils that have moderately fine texture to moderately coarse texture.
These soils have a moderate rate of water transmission.
Group C. Soils having a slow infiltration rate when thoroughly wet. These consist
chiefly of soils having a layer that impedes the downward movement of water or
soils of moderately fine texture or fine texture. These soils have a slow rate of
water transmission.
Group D. Soils having a very slow infiltration rate (high runoff potential) when
thoroughly wet. These consist chiefly of clays that have a high shrink-swell
potential, soils that have a high water table, soils that have a claypan or clay
layer at or near the surface, and soils that are shallow over nearly impervious
material. These soils have a very slow rate of water transmission.
If a soil is assigned to a dual hydrologic group (A/D, B/D, or C/D), the first letter is
for drained areas and the second is for undrained areas. Only the soils that in
their natural condition are in group D are assigned to dual classes.
Rating Options
Aggregation Method: Dominant Condition
Component Percent Cutoff: None Specified
Tie-break Rule: Higher
Hydrologic Soil Group—Union County, North Carolina Property Line
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
3/13/2017
Page 4 of 4
SOUTHSTONE
TAC-17000
PRECIPITATION DATA
Element Details
154ID Notes
CharlotteLabel
1 inch
1 inchLabel min5.00Increment
years0Return Event min360.00End Time
min0.00Start Time IncrementalStorm Event Depth Type
1 inch
Depth
(in)
Depth
(in)
Depth
(in)
Depth
(in)
Depth
(in)
Time
(min)
0.0030.0030.0030.0030.0000.00
0.0040.0040.0040.0030.00325.00
0.0040.0040.0040.0040.00450.00
0.0060.0050.0050.0050.00575.00
0.0080.0080.0070.0070.007100.00
0.0120.0110.0100.0090.009125.00
0.0390.0250.0220.0190.013150.00
0.0430.0750.1880.1080.050175.00
0.0120.0140.0200.0230.028200.00
0.0080.0090.0090.0100.011225.00
0.0060.0070.0070.0070.008250.00
0.0050.0050.0050.0050.005275.00
0.0040.0040.0040.0040.004300.00
0.0030.0030.0040.0040.004325.00
(N/A)(N/A)0.0030.0030.003350.00
1 year 24 hr
1 year 24 hrLabel min6.00Increment
years1Return Event min1,440.00End Time
min0.00Start Time IncrementalStorm Event Depth Type
1 year 24 hr
Depth
(in)
Depth
(in)
Depth
(in)
Depth
(in)
Depth
(in)
Time
(min)
0.0030.0030.0030.0030.0000.00
0.0030.0030.0030.0030.00330.00
0.0030.0030.0030.0030.00360.00
0.0030.0030.0030.0030.00390.00
0.0030.0030.0030.0030.003120.00
0.0030.0030.0030.0030.003150.00
0.0040.0030.0030.0030.003180.00
0.0040.0030.0040.0040.003210.00
0.0040.0040.0040.0040.004240.00
0.0040.0040.0040.0040.004270.00
10/20/2017TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
1 year 24 hr
Depth
(in)
Depth
(in)
Depth
(in)
Depth
(in)
Depth
(in)
Time
(min)
0.0040.0040.0040.0040.004300.00
0.0050.0040.0040.0050.004330.00
0.0050.0050.0050.0050.005360.00
0.0050.0050.0050.0050.005390.00
0.0050.0050.0050.0050.005420.00
0.0060.0050.0050.0050.005450.00
0.0070.0060.0060.0060.006480.00
0.0080.0080.0080.0070.007510.00
0.0080.0080.0080.0080.008540.00
0.0100.0090.0090.0090.008570.00
0.0120.0120.0110.0110.010600.00
0.0170.0160.0150.0140.013630.00
0.0270.0250.0220.0200.018660.00
0.3540.1970.1230.0610.030690.00
0.0320.0370.0430.0490.245720.00
0.0180.0190.0210.0220.025750.00
0.0130.0140.0140.0160.017780.00
0.0100.0110.0110.0120.012810.00
0.0090.0090.0090.0100.010840.00
0.0080.0080.0090.0090.009870.00
0.0070.0070.0080.0080.008900.00
0.0060.0070.0070.0070.007930.00
0.0060.0060.0060.0060.006960.00
0.0050.0050.0050.0060.006990.00
0.0050.0050.0050.0050.0051,020.00
0.0050.0050.0050.0050.0051,050.00
0.0040.0050.0040.0050.0051,080.00
0.0040.0040.0040.0040.0041,110.00
0.0040.0040.0040.0040.0041,140.00
0.0040.0030.0040.0040.0041,170.00
0.0030.0030.0030.0030.0031,200.00
0.0030.0030.0030.0030.0031,230.00
0.0030.0030.0030.0030.0031,260.00
0.0030.0030.0030.0030.0031,290.00
0.0030.0030.0030.0030.0031,320.00
0.0030.0030.0030.0030.0031,350.00
0.0030.0030.0030.0030.0031,380.00
0.0030.0030.0030.0030.0031,410.00
(N/A)(N/A)(N/A)(N/A)0.0031,440.00
2 year
2 yearLabel min5.00Increment
years2Return Event min360.00End Time
min0.00Start Time IncrementalStorm Event Depth Type
10/20/2017TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
2 year
Depth
(in)
Depth
(in)
Depth
(in)
Depth
(in)
Depth
(in)
Time
(min)
0.0080.0080.0070.0070.0000.00
0.0090.0090.0080.0080.00825.00
0.0100.0100.0100.0090.00950.00
0.0140.0120.0110.0110.01175.00
0.0180.0170.0160.0150.014100.00
0.0280.0260.0240.0220.021125.00
0.0890.0580.0500.0440.031150.00
0.1000.1680.4200.2420.115175.00
0.0290.0330.0470.0540.064200.00
0.0180.0210.0230.0250.027225.00
0.0140.0150.0160.0160.017250.00
0.0100.0110.0110.0120.012275.00
0.0090.0090.0090.0100.010300.00
0.0080.0080.0080.0080.009325.00
(N/A)(N/A)0.0070.0070.008350.00
10 year
10 yearLabel min5.00Increment
years10Return Event min360.00End Time
min0.00Start Time IncrementalStorm Event Depth Type
10 year
Depth
(in)
Depth
(in)
Depth
(in)
Depth
(in)
Depth
(in)
Time
(min)
0.0120.0120.0110.0110.0000.00
0.0130.0130.0130.0120.01225.00
0.0160.0150.0150.0140.01450.00
0.0230.0180.0180.0170.01675.00
0.0290.0270.0260.0250.024100.00
0.0490.0450.0420.0390.036125.00
0.1610.1030.0890.0790.054150.00
0.1770.2750.5900.3950.201175.00
0.0510.0570.0840.0960.112200.00
0.0300.0380.0400.0430.047225.00
0.0230.0240.0250.0270.028250.00
0.0160.0170.0170.0180.019275.00
0.0140.0140.0150.0150.016300.00
0.0120.0120.0130.0130.013325.00
(N/A)(N/A)0.0110.0110.012350.00
25 year
25 yearLabel min5.00Increment
years25Return Event min360.00End Time
10/20/2017TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
25 year
min0.00Start Time IncrementalStorm Event Depth Type
25 year
Depth
(in)
Depth
(in)
Depth
(in)
Depth
(in)
Depth
(in)
Time
(min)
0.0150.0140.0140.0140.0000.00
0.0170.0160.0160.0150.01525.00
0.0190.0190.0180.0180.01750.00
0.0250.0230.0220.0210.02075.00
0.0330.0310.0290.0280.027100.00
0.0580.0530.0490.0460.043125.00
0.1890.1200.1040.0930.064150.00
0.2080.3240.6800.4660.235175.00
0.0610.0670.0980.1110.131200.00
0.0340.0450.0480.0510.055225.00
0.0260.0270.0290.0300.032250.00
0.0200.0210.0210.0220.023275.00
0.0170.0170.0180.0190.019300.00
0.0150.0150.0160.0160.016325.00
(N/A)(N/A)0.0140.0140.014350.00
50 year
50 yearLabel min5.00Increment
years50Return Event min360.00End Time
min0.00Start Time IncrementalStorm Event Depth Type
50 year
Depth
(in)
Depth
(in)
Depth
(in)
Depth
(in)
Depth
(in)
Time
(min)
0.0170.0160.0160.0160.0000.00
0.0190.0190.0180.0180.01725.00
0.0220.0220.0210.0200.02050.00
0.0310.0260.0250.0240.02375.00
0.0390.0370.0350.0330.032100.00
0.0660.0610.0560.0530.049125.00
0.2090.1330.1160.1030.073150.00
0.2310.3560.7490.5130.260175.00
0.0690.0770.1090.1240.145200.00
0.0400.0510.0540.0580.063225.00
0.0310.0330.0340.0360.038250.00
0.0230.0230.0240.0250.026275.00
0.0190.0200.0210.0210.022300.00
0.0170.0170.0180.0180.019325.00
(N/A)(N/A)0.0160.0160.017350.00
10/20/2017TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
100 year
100 yearLabel min5.00Increment
years100Return Event min360.00End Time
min0.00Start Time IncrementalStorm Event Depth Type
100 year
Depth
(in)
Depth
(in)
Depth
(in)
Depth
(in)
Depth
(in)
Time
(min)
0.0180.0180.0170.0170.0000.00
0.0210.0200.0200.0200.01925.00
0.0240.0230.0230.0220.02250.00
0.0320.0280.0270.0260.02575.00
0.0410.0390.0370.0350.034100.00
0.0710.0650.0600.0560.053125.00
0.2260.1470.1260.1130.078150.00
0.2500.3860.8300.5550.282175.00
0.0740.0820.1190.1360.160200.00
0.0420.0550.0580.0630.068225.00
0.0330.0340.0360.0380.040250.00
0.0250.0250.0260.0270.029275.00
0.0210.0220.0220.0230.024300.00
0.0190.0190.0200.0200.021325.00
(N/A)(N/A)0.0170.0180.018350.00
10/20/2017TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
100 year 50 year 25 year 10 year
2 year 1 year 24 hr 1 inchDepth(in)0.875
0.750
0.625
0.500
0.375
0.250
0.125
0.000
Time (min)
1,400.001,200.001,000.00800.00600.00400.00200.000.00
10/20/2017TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
SOUTHSTONE
TAC-17000
PRE-DEVELOPMENT HYDROLOGIC
CALCULATIONS
Project Name: Southstone Date:1/12/2018
Project Number:TAC-17000 Calculated By: J. Mattingly, EI
INPUT SUMMARY
Total Area
Subbasin ID Impervious Open Wooded Pond Total Impervious 1/2 Acre Lot 1/3 Acre Lot Right of Way Open Wooded Pond Total [acres]SCS CN Tc [min]
1 0.52 0.59 22.48 0.00 23.60 0.00 6.44 22.10 4.39 0.79 0.76 0.00 34.48 58.07 67 26.85
2 1.57 4.45 38.19 0.00 44.21 0.04 3.29 6.87 1.92 0.87 5.42 0.00 18.42 62.63 73 30.23
3 0.00 0.11 4.15 0.00 4.26 19.62 6.48 25.81 11.73 53.30 111.54 2.07 230.54 234.81 74 42.97
4 0.83 2.04 10.50 0.00 13.36 1.03 0.00 1.32 0.00 3.90 9.75 0.00 16.00 29.36 68 23.96
Unanalyzed 0.04 0.42 2.23 0.00 2.69 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2.69 57 -
Totals 2.96 7.60 77.56 0.00 88.12 20.69 16.21 56.11 18.05 58.86 127.47 2.07 299.45 387.56
1-YEAR VOLUME SUMMARY
Subbasin ID [cf][acre-feet]
1 12,862 0.30
2 84,194 1.93
3 6,343 0.15
4 18,661 0.43
Unanalyzed 1,227 0.03
Totals 123,288 2.83
PRE DEVELOPMENT HYDROLOGIC SUMMARY
Onsite Area [acres]
1-Year Runoff Volume
Offsite Area [acres]
Project Name: Southstone Date:1/12/2018
Project Number:TAC-17000 Calculated By: J. Mattingly, EI
Subbasin ID:1
SCS CURVE NUMBER
(REF: TR-55 and NRCS Web Soil Survey).
HSG Impervious Open Wooded Pond 1/2 Acre Lot 1/3 Acre Lot Right of Way
A 98 39 30 100 54 57 77
B 98 61 55 100 70 72 85
C 98 74 70 100 80 81 90
D 98 80 77 100 85 86 92
HSG 'A' =0%
HSG 'B' =88%
HSG 'C' =12%
HSG 'D' =0%
Cover Composite
Condition SCS CN
Impervious 98
Open 63
Wooded 57
Pond 100
1/2 Acre Lot 71
1/3 Acre Lot 73
Right of Way 86
WATERSHED BREAKDOWN
Composite Area Area
SCS CN [sf][acres]
98 22,705 0.52
63 25,837 0.59
57 979,259 22.48
100 0 0.00
98 0 0.00
71 280,617 6.44
73 962,678 22.10
86 191,261 4.39
63 34,275 0.79
57 33,114 0.76
100 0 0.00
Total Area =2,529,746 sf
=58.07 acres
Composite SCS CN =67
% Impervious =20.00%
TIME OF CONCENTRATION
(REF: SCS Segmental Approach, TR-55).
Segment 1: Overland Flow Segment 2: Concentrated Flow
Length =100 ft Length =174 ft
Upstream Elevation =662.00 ft Upstream Elevation =660.00 ft
Downstream Elevation =660.00 ft Downstream Elevation =645.00 ft
Height =2.00 ft Height =15.00 ft
Slope =0.0200 ft/ft Slope =0.0862 ft/ft
Manning's n =0.40 wooded-light underbrush Paved?No
P (2-year/24-hour) =3.51 inches (Charlotte, NC)Velocity =4.74 ft/sec
Segment Time =20.50 minutes Segment Time =0.61 minutes
Segment 3: Channel Flow Segment 4: Channel Flow
Length =1495 ft Length =46 ft
Upstream Elevation =645.00 ft Upstream Elevation =598.50 ft
Downstream Elevation =598.50 ft Downstream Elevation =598.00 ft
Height =46.50 ft Height =0.50 ft
Slope =0.0311 ft/ft Slope =0.0109 ft/ft
Manning's n =0.045 natural channel Manning's n =0.045 natural channel
Flow Area =4 sf (assume 2'x2' channel)Flow Area =36 sf (assume 6'x6' channel)
Wetted Perimeter =6 lf (assume 2'x2' channel)Wetted Perimeter =18 lf (assume 6'x6' channel)
Channel Velocity =4.46 ft/sec Channel Velocity =5.48 ft/sec
Segment Time =5.59 minutes Segment Time =0.14 minutes
Time of Concentration =26.85 minutes
SCS Lag Time =16.11 minutes
Offsite Pond -
Offsite Wooded Assume good condition
Offsite Impervious -
Offsite Open Assume good condition
Offsite 1/2 Acre Lot Assume 25% impervious
Offsite 1/3 Acre Lot Assume 30% impervious
Offsite Right of Way Assume 65% Impervious
Assume good condition
-
Assume good condition
Onsite Wooded
Onsite Pond
PRE DEVELOPMENT HYDROLOGIC CALCULATIONS
Comments
Contributing Area
Onsite Impervious
Onsite Open
Comments
-
Assume good condition
Assume 25% impervious
Assume 30% impervious
Assume 65% Impervious
-
Assume good condition
-
RUNOFF VOLUME CALCULATIONS
Runoff volume calculations are based upon the SCS Method
Q* = ((P-0.2*S)2)/ (P+0.8*S)
where,
Q* = direct runoff (inches)
S = potential abstraction = (1000/CN) - 10
P = accumulated storm rainfall (inches)
Onsite Drainage Area, A =23.60 acres
Onsite SCS CN =58
S =7.28
P (1-year/24-hour) =2.58 inches
Q* =0.15 inches
Onsite Runoff Volume =0.30 acre-ft
=12,862 cf
Project Name: Southstone Date:1/12/2018
Project Number:TAC-17000 Calculated By: J. Mattingly, EI
Subbasin ID:2
SCS CURVE NUMBER
(REF: TR-55 and NRCS Web Soil Survey).
HSG Impervious Open Wooded Pond 1/2 Acre Lot 1/3 Acre Lot Right of Way
A 98 39 30 100 54 57 77
B 98 61 55 100 70 72 85
C 98 74 70 100 80 81 90
D 98 80 77 100 85 86 92
HSG 'A' =0%
HSG 'B' =16%
HSG 'C' =57%
HSG 'D' =26%
Cover Composite
Condition SCS CN
Impervious 98
Open 73
Wooded 69
Pond 100
1/2 Acre Lot 80
1/3 Acre Lot 81
Right of Way 90
WATERSHED BREAKDOWN
Composite Area Area
SCS CN [sf][acres]
98 68,456 1.57
73 193,625 4.45
69 1,663,672 38.19
100 0 0.00
98 1,857 0.04
80 143,370 3.29
81 299,370 6.87
90 83,799 1.92
73 37,987 0.87
69 236,186 5.42
100 0 0.00
Total Area =2,728,322 sf
=62.63 acres
Composite SCS CN =73
% Impervious =9.18%
TIME OF CONCENTRATION
(REF: SCS Segmental Approach, TR-55).
Segment 1: Overland Flow Segment 2: Concentrated Flow
Length =100 ft Length =944 ft
Upstream Elevation =668.00 ft Upstream Elevation =665.50 ft
Downstream Elevation =665.50 ft Downstream Elevation =622.00 ft
Height =2.50 ft Height =43.50 ft
Slope =0.0250 ft/ft Slope =0.0461 ft/ft
Manning's n =0.40 wooded-light underbrush Paved?No
P (2-year/24-hour) =3.51 inches (Charlotte, NC)Velocity =3.46 ft/sec
Segment Time =18.75 minutes Segment Time =4.54 minutes
Segment 3: Channel Flow Segment 4: Channel Flow
Length =269 ft Length =1136 ft
Upstream Elevation =622.00 ft Upstream Elevation =612.00 ft
Downstream Elevation =612.00 ft Downstream Elevation =605.00 ft
Height =10.00 ft Height =7.00 ft
Slope =0.0372 ft/ft Slope =0.0062 ft/ft
Manning's n =0.045 natural channel Manning's n =0.045 natural channel
Flow Area =4 sf (assume 2'x2' channel)Flow Area =16 sf (assume 4'x4' channel)
Wetted Perimeter =6 lf (assume 2'x2' channel)Wetted Perimeter =12 lf (assume 4'x4' channel)
Channel Velocity =4.87 ft/sec Channel Velocity =3.15 ft/sec
Segment Time =0.92 minutes Segment Time =6.01 minutes
Time of Concentration =30.23 minutes
SCS Lag Time =18.14 minutes
Contributing Area Comments
Onsite Impervious -
-
Assume 25% impervious
Assume 30% impervious
Assume 65% Impervious
PRE DEVELOPMENT HYDROLOGIC CALCULATIONS
Comments
-
Assume good condition
Assume good condition
Onsite Open Assume good condition
Onsite Wooded Assume good condition
Onsite Pond -
Offsite Pond -
Offsite Impervious -
Offsite Open Assume good condition
Offsite Wooded Assume good condition
Offsite 1/2 Acre Lot Assume 25% impervious
Offsite 1/3 Acre Lot Assume 30% impervious
Offsite Right of Way Assume 65% Impervious
RUNOFF VOLUME CALCULATIONS
Runoff volume calculations are based upon the SCS Method
where,
Q* = direct runoff (inches)
S = potential abstraction = (1000/CN) - 10
P = accumulated storm rainfall (inches)
Onsite Drainage Area, A =44.21 acres
Onsite SCS CN =71
S =4.12
P (1-year/24-hour) =2.58 inches
Q* =0.52 inches
Onsite Runoff Volume =1.93 acre-ft
=84,194 cf
Q* = ((P-0.2*S)2)/ (P+0.8*S)
Project Name: Southstone Date:1/12/2018
Project Number:TAC-17000 Calculated By: J. Mattingly, EI
Subbasin ID:3
SCS CURVE NUMBER
(REF: TR-55 and NRCS Web Soil Survey).
HSG Impervious Open Wooded Pond 1/2 Acre Lot 1/3 Acre Lot Right of Way
A 98 39 30 100 54 57 77
B 98 61 55 100 70 72 85
C 98 74 70 100 80 81 90
D 98 80 77 100 85 86 92
HSG 'A' =0%
HSG 'B' =20%
HSG 'C' =73%
HSG 'D' =7%
Cover Composite
Condition SCS CN
Impervious 98
Open 72
Wooded 67
Pond 100
1/2 Acre Lot 78
1/3 Acre Lot 80
Right of Way 89
WATERSHED BREAKDOWN
Composite Area Area
SCS CN [sf][acres]
98 0 0.00
72 4,680 0.11
67 180,958 4.15
100 0 0.00
98 854,495 19.62
78 282,086 6.48
80 1,124,430 25.81
89 511,161 11.73
72 2,321,801 53.30
67 4,858,503 111.54
100 90,025 2.07
Total Area =10,228,139 sf
=234.81 acres
Composite SCS CN =74
% Impervious =15.59%
TIME OF CONCENTRATION
(REF: SCS Segmental Approach, TR-55).
Segment 1: Overland Flow Segment 2: Concentrated Flow
Length =100 ft Length =876 ft
Upstream Elevation =736.00 ft Upstream Elevation =734.50 ft
Downstream Elevation =734.50 ft Downstream Elevation =712.00 ft
Height =1.50 ft Height =22.50 ft
Slope =0.0150 ft/ft Slope =0.0257 ft/ft
Manning's n =0.24 dense grasses Paved?No
P (2-year/24-hour) =3.51 inches (Charlotte, NC)Velocity =2.59 ft/sec
Segment Time =15.29 minutes Segment Time =5.65 minutes
Segment 3: Channel Flow Segment 4: Pipe Flow
Length =1799 ft Length =1353 ft
Upstream Elevation =712.00 ft Upstream Elevation =668.00 ft
Downstream Elevation =668.00 ft Downstream Elevation =647.00 ft
Height =44.00 ft Height =21.00 ft
Slope =0.0245 ft/ft Slope =0.0155 ft/ft
Manning's n =0.045 natural channel Manning's n =0.013 RCP
Flow Area =9 sf (assume 3'x3' channel)Flow Area =1.8 sf (assume 18" RCP)
Wetted Perimeter =9 lf (assume 3'x3' channel)Wetted Perimeter =4.7 lf (assume 18" RCP)
Channel Velocity =5.18 ft/sec Channel Velocity =7.43 ft/sec
Segment Time =5.79 minutes Segment Time =3.04 minutes
Contributing Area Comments
Onsite Impervious -
-
Assume 25% impervious
Assume 30% impervious
Assume 65% Impervious
PRE DEVELOPMENT HYDROLOGIC CALCULATIONS
Comments
-
Assume good condition
Assume good condition
Onsite Open Assume good condition
Onsite Wooded Assume good condition
Onsite Pond -
Offsite Pond -
Offsite Impervious -
Offsite Open Assume good condition
Offsite Wooded Assume good condition
Offsite 1/2 Acre Lot Assume 25% impervious
Offsite 1/3 Acre Lot Assume 30% impervious
Offsite Right of Way Assume 65% Impervious
Segment 5: Channel Flow Segment 6: Pipe Flow
Length =1735 ft Length =51 ft
Upstream Elevation =647.00 ft Upstream Elevation =628.00 ft
Downstream Elevation =628.00 ft Downstream Elevation =627.00 ft
Height =19.00 ft Height =1.00 ft
Slope =0.0110 ft/ft Slope =0.0196 ft/ft
Manning's n =0.045 natural channel Manning's n =0.013 RCP
Flow Area =16 sf (assume 4'x4' channel)Flow Area =1.8 sf (assume 18" RCP)
Wetted Perimeter =12 lf (assume 4'x4' channel)Wetted Perimeter =4.7 lf (assume 18" RCP)
Channel Velocity =4.20 ft/sec Channel Velocity =8.35 ft/sec
Segment Time =6.89 minutes Segment Time =0.10 minutes
Segment 7: Channel Flow
Length =1498 ft
Upstream Elevation =627.00 ft
Downstream Elevation =612.00 ft
Height =15.00 ft
Slope =0.0100 ft/ft
Manning's n =0.045 natural channel
Flow Area =16 sf (assume 4'x4' channel)
Wetted Perimeter =12 lf (assume 4'x4' channel)
Channel Velocity =4.01 ft/sec
Segment Time =6.22 minutes
Time of Concentration =42.97 minutes
SCS Lag Time =25.78 minutes
RUNOFF VOLUME CALCULATIONS
Runoff volume calculations are based upon the SCS Method
where,
Q* = direct runoff (inches)
S = potential abstraction = (1000/CN) - 10
P = accumulated storm rainfall (inches)
Onsite Drainage Area, A =4.26 acres
Onsite SCS CN =68
S =4.79
P (1-year/24-hour) =2.58 inches
Q* =0.41 inches
Onsite Runoff Volume =0.15 acre-ft
=6,343 cf
Q* = ((P-0.2*S)2)/ (P+0.8*S)
Project Name: Southstone Date:1/12/2018
Project Number:TAC-17000 Calculated By: J. Mattingly, EI
Subbasin ID:4
SCS CURVE NUMBER
(REF: TR-55 and NRCS Web Soil Survey).
HSG Impervious Open Wooded Pond 1/2 Acre Lot 1/3 Acre Lot Right of Way
A 98 39 30 100 54 57 77
B 98 61 55 100 70 72 85
C 98 74 70 100 80 81 90
D 98 80 77 100 85 86 92
HSG 'A' =0%
HSG 'B' =40%
HSG 'C' =60%
HSG 'D' =0%
Cover Composite
Condition SCS CN
Impervious 98
Open 69
Wooded 64
Pond 100
1/2 Acre Lot 76
1/3 Acre Lot 77
Right of Way 88
WATERSHED BREAKDOWN
Composite Area Area
SCS CN [sf][acres]
98 35,977 0.83
69 88,752 2.04
64 457,276 10.50
100 0 0.00
98 44,849 1.03
76 0 0.00
77 57,641 1.32
88 0 0.00
69 169,754 3.90
64 424,576 9.75
100 0 0.00
Total Area =1,278,825 sf
=29.36 acres
Composite SCS CN =68
% Impervious =7.67%
TIME OF CONCENTRATION
(REF: SCS Segmental Approach, TR-55).
Segment 1: Overland Flow Segment 2: Concentrated Flow
Length =100 ft Length =387 ft
Upstream Elevation =671.00 ft Upstream Elevation =669.00 ft
Downstream Elevation =669.00 ft Downstream Elevation =649.00 ft
Height =2.00 ft Height =20.00 ft
Slope =0.0200 ft/ft Slope =0.0517 ft/ft
Manning's n =0.40 wooded-light underbrush Paved?No
P (2-year/24-hour) =3.51 inches (Charlotte, NC)Velocity =3.67 ft/sec
Segment Time =20.50 minutes Segment Time =1.76 minutes
Segment 3: Channel Flow Segment 4: Channel Flow
Length =464 ft Length =612 ft
Upstream Elevation =649.00 ft Upstream Elevation =634.00 ft
Downstream Elevation =634.00 ft Downstream Elevation =625.00 ft
Height =15.00 ft Height =9.00 ft
Slope =0.0323 ft/ft Slope =0.0147 ft/ft
Manning's n =0.045 natural channel Manning's n =0.045 natural channel
Flow Area =4 sf (assume 2'x2' channel)Flow Area =4 sf (assume 2'x2' channel)
Wetted Perimeter =6 lf (assume 2'x2' channel)Wetted Perimeter =6 lf (assume 2'x2' channel)
Channel Velocity =4.54 ft/sec Channel Velocity =3.06 ft/sec
Segment Time =1.70 minutes Segment Time =3.33 minutes
Time of Concentration =23.96 minutes
SCS Lag Time =14.38 minutes
Assume 25% impervious
Assume 30% impervious
Assume 65% Impervious
Offsite 1/2 Acre Lot Assume 25% impervious
-
Offsite 1/3 Acre Lot Assume 30% impervious
Offsite Right of Way Assume 65% Impervious
-
Contributing Area Comments
Onsite Impervious -
Onsite Open Assume good condition
Onsite Wooded Assume good condition
Onsite Pond -
Offsite Impervious
PRE DEVELOPMENT HYDROLOGIC CALCULATIONS
Comments
-
Assume good condition
Assume good condition
Offsite Open Assume good condition
Offsite Wooded Assume good condition
Offsite Pond -
RUNOFF VOLUME CALCULATIONS
Runoff volume calculations are based upon the SCS Method
Q* = ((P-0.2*S)2)/ (P+0.8*S)
where,
Q* = direct runoff (inches)
S = potential abstraction = (1000/CN) - 10
P = accumulated storm rainfall (inches)
Onsite Drainage Area, A =13.36 acres
Onsite SCS CN =67
S =4.96
P (1-year/24-hour) =2.58 inches
Q* =0.38 inches
Onsite Runoff Volume =0.43 acre-ft
=18,661 cf
Project Name: Southstone Date:1/12/2018
Project Number:TAC-17000 Calculated By: J. Mattingly, EI
Subbasin ID:Unanalyzed
SCS CURVE NUMBER
(REF: TR-55 and NRCS Web Soil Survey).
HSG Impervious Open Wooded Pond 1/2 Acre Lot 1/3 Acre Lot Right of Way
A 98 39 30 100 54 57 77
B 98 61 55 100 70 72 85
C 98 74 70 100 80 81 90
D 98 80 77 100 85 86 92
HSG 'A' =0%
HSG 'B' =100%
HSG 'C' =0%
HSG 'D' =0%
Cover Composite
Condition SCS CN
Impervious 98
Open 61
Wooded 55
Pond 100
1/2 Acre Lot 70
1/3 Acre Lot 72
Right of Way 85
WATERSHED BREAKDOWN
Composite Area Area
SCS CN [sf][acres]
98 1,798 0.04
61 18,254 0.42
55 97,244 2.23
100 0 0.00
98 0 0.00
70 0 0.00
72 0 0.00
85 0 0.00
61 0 0.00
55 0 0.00
100 0 0.00
Total Area =117,296 sf
=2.69 acres
Composite SCS CN =57
% Impervious =1.53%
RUNOFF VOLUME CALCULATIONS
Runoff volume calculations are based upon the SCS Method
where,
Q* = direct runoff (inches)
S = potential abstraction = (1000/CN) - 10
P = accumulated storm rainfall (inches)
Onsite Drainage Area, A =2.69 acres
Onsite SCS CN =57
S =7.67
P (1-year/24-hour) =2.58 inches
Q* =0.13 inches
Onsite Runoff Volume =0.03 acre-ft
=1,227 cf
Assume 25% impervious
Assume 30% impervious
Assume 65% Impervious
Offsite 1/2 Acre Lot Assume 25% impervious
-
Offsite 1/3 Acre Lot Assume 30% impervious
Offsite Right of Way Assume 65% Impervious
-
Contributing Area Comments
Onsite Impervious -
Onsite Open Assume good condition
Onsite Wooded Assume good condition
Onsite Pond -
Offsite Impervious
PRE DEVELOPMENT HYDROLOGIC CALCULATIONS
Comments
-
Assume good condition
Assume good condition
Q* = ((P-0.2*S)2)/ (P+0.8*S)
Offsite Open Assume good condition
Offsite Wooded Assume good condition
Offsite Pond -
Project Name: Southstone Date:1/12/2018
Project Number:TAC-17000 Calculated By: J. Mattingly, EI
Subbasin ID:Reach Data
REACH DATA
(REF: SCS Segmental Approach, TR-55).
REACH 1: POA 2 to POA 1
Length =962 ft
Upstream Elevation =605.00 ft
Downstream Elevation =598.00 ft
Height =7.00 ft
Slope =0.0073 ft/ft
Manning's n =0.045 natural channel
Flow Area =36 sf (assume 6'x6' channel)
Wetted Perimeter =18 lf (assume 6'x6' channel)
Channel Velocity =4.48 ft/sec
Segment Time =3.58 minutes
REACH 2: POA 3 to POA 2
Length =1136 ft
Upstream Elevation =612.00 ft
Downstream Elevation =605.00 ft
Height =7.00 ft
Slope =0.0062 ft/ft
Manning's n =0.045 natural channel
Flow Area =16 sf (assume 4'x4' channel)
Wetted Perimeter =12 lf (assume 4'x4' channel)
Channel Velocity =3.15 ft/sec
Segment Time =6.01 minutes
REACH 3: POA 4 to POA 2
Length =1026 ft
Upstream Elevation =625.00 ft
Downstream Elevation =605.00 ft
Height =20.00 ft
Slope =0.0195 ft/ft
Manning's n =0.045 natural channel
Flow Area =4 sf (assume 2'x2' channel)
Wetted Perimeter =6 lf (assume 2'x2' channel)
Channel Velocity =3.53 ft/sec
Segment Time =4.85 minutes
PRE DEVELOPMENT HYDROLOGIC CALCULATIONS
RE
A
CH2
REACH110/20/2017TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Subsection: Master Network Summary
Catchments Summary
Peak Flow
(ft³/s)
Time to Peak
(min)
Hydrograph
Volume
(ft³)
Return
Event
(years)
ScenarioLabel
14.19734.0081,375.0001Pre 1 Year1
13.59208.0056,982.0002Pre 2 Year1
60.05204.00206,322.00010Pre 10 Year1
86.85204.00291,998.00025Pre 25 Year1
130.03201.00430,782.000100Pre 100 Year1
27.45734.00137,641.0001Pre 1 Year2
27.00206.00103,180.0002Pre 2 Year2
86.31205.00302,962.00010Pre 10 Year2
117.83205.00410,499.00025Pre 25 Year2
166.62202.00579,725.000100Pre 100 Year2
87.54744.00549,534.0001Pre 1 Year3
90.18218.00417,438.0002Pre 2 Year3
277.43212.001,190,629.00010Pre 10 Year3
377.50212.001,602,885.00025Pre 25 Year3
530.44212.002,248,805.000100Pre 100 Year3
8.77731.0044,710.0001Pre 1 Year4
8.27204.0031,688.0002Pre 2 Year4
34.40201.00110,212.00010Pre 10 Year4
49.32201.00154,742.00025Pre 25 Year4
72.74199.00226,502.000100Pre 100 Year4
Node Summary
Peak Flow
(ft³/s)
Time to Peak
(min)
Hydrograph
Volume
(ft³)
Return
Event
(years)
ScenarioLabel
123.19749.00810,449.0001Pre 1 YearPOA1
127.46222.00609,288.0002Pre 2 YearPOA1
409.21217.001,810,126.00010Pre 10 YearPOA1
562.76216.002,460,125.00025Pre 25 YearPOA1
799.78216.003,485,813.000100Pre 100 YearPOA1
114.45745.00730,355.0001Pre 1 YearPOA2
117.05218.00552,306.0002Pre 2 YearPOA2
367.65218.001,603,804.00010Pre 10 YearPOA2
500.84213.002,168,127.00025Pre 25 YearPOA2
709.09213.003,055,031.000100Pre 100 YearPOA2
87.54744.00549,534.0001Pre 1 YearPOA3
90.18218.00417,438.0002Pre 2 YearPOA3
277.43212.001,190,629.00010Pre 10 YearPOA3
377.50212.001,602,885.00025Pre 25 YearPOA3
530.44212.002,248,805.000100Pre 100 YearPOA3
8.77731.0044,710.0001Pre 1 YearPOA4
8.27204.0031,688.0002Pre 2 YearPOA4
34.40201.00110,212.00010Pre 10 YearPOA4
1/12/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Subsection: Master Network Summary
Node Summary
Peak Flow
(ft³/s)
Time to Peak
(min)
Hydrograph
Volume
(ft³)
Return
Event
(years)
ScenarioLabel
49.32201.00154,742.00025Pre 25 YearPOA4
72.74199.00226,502.000100Pre 100 YearPOA4
1/12/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
SOUTHSTONE
TAC-17000
POST-DEVELOPMENT HYDROLOGIC
CALCULATIONS
Project Name: Southstone Date:1/18/2018
Project Number:TAC-17000 Calculated By: J. Mattingly, EI
INPUT SUMMARY
Total Area
Subbasin ID Impervious Open Wooded Pond Total Impervious 1/2 Acre Lot 1/3 Acre Lot Right of Way Open Wooded Pond Total [acres]SCS CN Tc [min]
1 To SWMF A 2.13 4.25 0.48 0.42 7.29 0.00 2.55 0.00 0.00 0.00 0.00 0.00 2.55 9.84 73 5.00
1 To SWMF B 5.62 7.01 0.37 0.60 13.60 0.00 3.89 0.00 0.00 0.00 0.00 0.00 3.89 17.49 78 5.00
1 Bypass 1.17 5.05 3.49 0.00 9.72 0.00 0.00 22.10 4.39 0.79 0.76 0.00 28.04 37.75 72 10.73
2 To SWMF C 3.82 5.09 0.00 0.37 9.28 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 9.28 85 5.00
2 To SWMF D 3.35 4.73 0.52 0.64 9.24 0.00 3.29 0.00 0.00 0.00 2.78 0.00 6.07 15.31 83 5.00
2 To SWMF E 6.01 6.82 2.13 0.33 15.30 0.11 0.00 0.20 0.00 0.54 1.09 0.00 1.94 17.24 82 5.00
2 Bypass 0.47 6.17 2.49 0.00 9.13 0.00 0.00 6.87 1.92 0.27 1.55 0.00 10.62 19.74 76 15.95
3 0.00 0.57 0.59 0.00 1.16 19.62 6.48 25.81 11.73 53.30 111.54 2.07 230.54 231.70 74 42.97
4 To SWMF F 2.51 4.44 0.62 0.29 7.86 0.02 0.00 1.12 0.00 0.40 4.19 0.00 5.73 13.60 70 5.00
4 Bypass 0.00 1.86 2.59 0.00 4.44 1.01 0.00 0.00 0.00 3.55 5.55 0.00 10.12 14.56 73 23.96
Unanalyzed 0.00 1.11 0.00 0.00 1.11 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 1.11 61 -
Totals 25.08 47.09 13.28 2.66 88.12 20.75 16.21 56.10 18.05 58.85 127.47 2.07 299.50 387.62
Subbasin ID 56x66 Lots 50x65 Lots
1 To SWMF A 15.00 0.00
1 To SWMF B 6.75 29.50
1 Bypass 2.75 9.75
2 To SWMF C 10.00 11.00
2 To SWMF D 0.00 23.75
2 To SWMF E 7.25 29.00
2 Bypass 3.75 1.00
3 0.00 0.00
4 To SWMF F 16.50 0.00
4 Bypass 0.00 0.00
Unanalyzed 0.00 0.00
Totals 62.00 104.00
POST DEVELOPMENT HYDROLOGIC SUMMARY
Onsite Area [acres]Offsite Area [acres]
1-YEAR VOLUME SUMMARY
Subbasin ID [cf][acre-feet]
1 75,316 1.73 Includes 1-To SWMF A, 1-To SWMF B, and 1-Bypass
2 165,101 3.79 Includes 2-To SWMF C, 2-To SWMF D, 2-To SWMF E, and 2-Bypass
3 2,016 0.05
4 29,909 0.69 Includes 4-To SWMF F and 4-Bypass
Unanalyzed 883 0.02
Totals 273,225 6.27
Subbasin ID [cf][acre-feet][cf][acre-feet]
1 12,862 0.30 62,453 1.43
2 84,194 1.93 80,907 1.86
3 6,343 0.15 (4,328)(0.10)
4 18,661 0.43 11,248 0.26
Unanalyzed 1,227 0.03 (344)(0.01)
Totals 123,288 2.83 149,937 3.44
ALLOCATION OF 1-YEAR TREATMENT VOLUME
% Allocation based on drainage area to Stormwater Management Facility
Difference 1-Year Vol 1-Year Vol
1-Year Vol Req'd Provided
Subbasin ID Facility ID [cf]% Allocation [cf][cf]
SWMF A 40%24,981 25,489
SWMF B 60%37,472 37,472
SWMF C 25%20,227 20,227
SWMF D 50%40,453 40,453
SWMF E 25%20,227 23,329
4 SWMF F 11,248 100%11,248 11,836
Totals 154,609 158,806
1
2
62,453
80,907
1-Year Runoff Volume 1-Year Runoff Volume
Post Development
Pre Development Difference
1-Year Runoff Volume
Project Name: Southstone Date:1/18/2018
Project Number:TAC-17000 Calculated By: J. Mattingly, EI
Subbasin ID:1-To SWMF A
SCS CURVE NUMBER
(REF: TR-55 and NRCS Web Soil Survey).
HSG Impervious Open Wooded Pond 1/2 Acre Lot 1/3 Acre Lot Right of Way
A 98 39 30 100 54 57 77
B 98 61 55 100 70 72 85
C 98 74 70 100 80 81 90
D 98 80 77 100 85 86 92
HSG 'A' =0%
HSG 'B' =100%
HSG 'C' =0%
HSG 'D' =0%
Cover Composite
Condition SCS CN
Impervious 98
Open 61
Wooded 55
Pond 100
1/2 Acre Lot 70
1/3 Acre Lot 72
Right of Way 85
ONSITE IMPERVIOUS BREAKDOWN
Imp per Lot Imp Area
# of Lots [sf][sf]
15.00 4,350 65,250
0.00 4,000 0
--27,398
Total Onsite Impervious Area =92,648 sf
WATERSHED BREAKDOWN
Composite Area Area
SCS CN [sf][acres]
98 92,648 2.13
61 185,276 4.25
55 21,107 0.48
100 18,430 0.42
98 0 0.00
70 111,160 2.55
72 0 0.00
85 0 0.00
61 0 0.00
55 0 0.00
100 0 0.00
Total Area =428,621 sf
=9.84 acres
Composite SCS CN =73
% Impervious =28.10%
TIME OF CONCENTRATION
(REF: SCS Segmental Approach, TR-55).
Time of Concentration =5.00 minutes
SCS Lag Time =3.00 minutes
-
POST DEVELOPMENT HYDROLOGIC CALCULATIONS
Comments
-
Assume good condition
Assume good condition
Onsite Open Assume good condition
Assume 25% impervious
Assume 30% impervious
Assume 65% Impervious
Contributing Area
56' x 66' Lots
50' x 65' Lots
Measured Impervious
Contributing Area Comments
Onsite Impervious -
Onsite Wooded Assume good condition
Onsite Pond -
Offsite Impervious -
Offsite 1/2 Acre Lot Assume 25% impervious
Offsite 1/3 Acre Lot Assume 30% impervious
Offsite Right of Way Assume 65% Impervious
Offsite Open Assume good condition
Offsite Wooded Assume good condition
Offsite Pond -
RUNOFF VOLUME CALCULATIONS
Runoff volume calculations are based upon the SCS Method
Q* = ((P-0.2*S)2)/ (P+0.8*S)
where,
Q* = direct runoff (inches)
S = potential abstraction = (1000/CN) - 10
P = accumulated storm rainfall (inches)
Onsite Drainage Area, A =7.29 acres
Onsite SCS CN =74
S =3.58
P (1-year/24-hour) =2.58 inches
Q* =0.64 inches
Onsite Runoff Volume =0.39 acre-ft
=16,913 cf
Project Name: Southstone Date:1/18/2018
Project Number:TAC-17000 Calculated By: J. Mattingly, EI
Subbasin ID:1-To SWMF B
SCS CURVE NUMBER
(REF: TR-55 and NRCS Web Soil Survey).
HSG Impervious Open Wooded Pond 1/2 Acre Lot 1/3 Acre Lot Right of Way
A 98 39 30 100 54 57 77
B 98 61 55 100 70 72 85
C 98 74 70 100 80 81 90
D 98 80 77 100 85 86 92
HSG 'A' =0%
HSG 'B' =80%
HSG 'C' =0%
HSG 'D' =20%
Cover Composite
Condition SCS CN
Impervious 98
Open 65
Wooded 59
Pond 100
1/2 Acre Lot 73
1/3 Acre Lot 75
Right of Way 86
ONSITE IMPERVIOUS BREAKDOWN
Imp per Lot Imp Area
# of Lots [sf][sf]
6.75 4,350 29,363
29.50 4,000 118,000
--97,330
Total Onsite Impervious Area =244,693 sf
WATERSHED BREAKDOWN
Composite Area Area
SCS CN [sf][acres]
98 244,693 5.62
65 305,441 7.01
59 16,139 0.37
100 26,146 0.60
98 0 0.00
73 169,457 3.89
75 0 0.00
86 0 0.00
65 0 0.00
59 0 0.00
100 0 0.00
Total Area =761,876 sf
=17.49 acres
Composite SCS CN =78
% Impervious =37.68%
TIME OF CONCENTRATION
(REF: SCS Segmental Approach, TR-55).
Time of Concentration =5.00 minutes
SCS Lag Time =3.00 minutes
Offsite Open Assume good condition
Offsite Wooded Assume good condition
Offsite Pond -
Offsite 1/2 Acre Lot Assume 25% impervious
Offsite 1/3 Acre Lot Assume 30% impervious
Offsite Right of Way Assume 65% Impervious
Onsite Wooded Assume good condition
Onsite Pond -
Offsite Impervious -
Onsite Open Assume good condition
Assume 25% impervious
Assume 30% impervious
Assume 65% Impervious
Contributing Area
56' x 66' Lots
50' x 65' Lots
Measured Impervious
Contributing Area Comments
Onsite Impervious -
-
POST DEVELOPMENT HYDROLOGIC CALCULATIONS
Comments
-
Assume good condition
Assume good condition
RUNOFF VOLUME CALCULATIONS
Runoff volume calculations are based upon the SCS Method
where,
Q* = direct runoff (inches)
S = potential abstraction = (1000/CN) - 10
P = accumulated storm rainfall (inches)
Onsite Drainage Area, A =13.60 acres
Onsite SCS CN =80
S =2.51
P (1-year/24-hour) =2.58 inches
Q* =0.94 inches
Onsite Runoff Volume =1.07 acre-ft
=46,419 cf
Q* = ((P-0.2*S)2)/ (P+0.8*S)
Project Name: Southstone Date:1/18/2018
Project Number:TAC-17000 Calculated By: J. Mattingly, EI
Subbasin ID:1-Bypass
SCS CURVE NUMBER
(REF: TR-55 and NRCS Web Soil Survey).
HSG Impervious Open Wooded Pond 1/2 Acre Lot 1/3 Acre Lot Right of Way
A 98 39 30 100 54 57 77
B 98 61 55 100 70 72 85
C 98 74 70 100 80 81 90
D 98 80 77 100 85 86 92
HSG 'A' =0%
HSG 'B' =81%
HSG 'C' =19%
HSG 'D' =0%
Cover Composite
Condition SCS CN
Impervious 98
Open 63
Wooded 58
Pond 100
1/2 Acre Lot 72
1/3 Acre Lot 73
Right of Way 86
ONSITE IMPERVIOUS BREAKDOWN
Imp per Lot Imp Area
# of Lots [sf][sf]
2.75 4,350 11,963
9.75 4,000 39,000
--0
Total Onsite Impervious Area =50,963 sf
WATERSHED BREAKDOWN
Composite Area Area
SCS CN [sf][acres]
98 50,963 1.17
63 220,021 5.05
58 152,206 3.49
100 0 0.00
98 0 0.00
72 0 0.00
73 962,678 22.10
86 191,261 4.39
63 34,275 0.79
58 33,114 0.76
100 0 0.00
Total Area =1,644,518 sf
=37.75 acres
Composite SCS CN =72
% Impervious =28.22%
TIME OF CONCENTRATION
(REF: SCS Segmental Approach, TR-55).
Segment 1: Overland Flow Segment 2: Channel Flow
Length =77 ft Length =1158 ft
Upstream Elevation =638.00 ft Upstream Elevation =631.00 ft
Downstream Elevation =631.00 ft Downstream Elevation =598.50 ft
Height =7.00 ft Height =32.50 ft
Slope =0.0909 ft/ft Slope =0.0281 ft/ft
Manning's n =0.24 dense grasses Manning's n =0.045 natural channel
P (2-year/24-hour) =3.51 inches (Charlotte, NC)Flow Area =4 sf (assume 2'x2' channel)
Segment Time =6.03 minutes Wetted Perimeter =6 lf (assume 2'x2' channel)
Channel Velocity =4.23 ft/sec
Segment Time =4.56 minutes
Segment 3: Channel Flow
Length =46 ft
Upstream Elevation =598.50 ft
Downstream Elevation =598.00 ft
Height =0.50 ft
Slope =0.0109 ft/ft
Manning's n =0.045 natural channel
Flow Area =36 sf (assume 6'x6' channel)
Wetted Perimeter =18 lf (assume 6'x6' channel)
Channel Velocity =5.48 ft/sec
Segment Time =0.14 minutes
Time of Concentration =10.73 minutes
SCS Lag Time =6.44 minutes
Offsite Pond -
Offsite Wooded Assume good condition
Offsite Impervious -
Offsite Open Assume good condition
Offsite 1/2 Acre Lot Assume 25% impervious
Offsite 1/3 Acre Lot Assume 30% impervious
Offsite Right of Way Assume 65% Impervious
Assume good condition
-
Assume good condition
Onsite Wooded
Onsite Pond
Contributing Area
56' x 66' Lots
50' x 65' Lots
Measured Impervious
POST DEVELOPMENT HYDROLOGIC CALCULATIONS
Comments
Contributing Area
Onsite Impervious
Onsite Open
Comments
-
Assume good condition
Assume 25% impervious
Assume 30% impervious
Assume 65% Impervious
-
Assume good condition
-
RUNOFF VOLUME CALCULATIONS
Runoff volume calculations are based upon the SCS Method
Q* = ((P-0.2*S)2)/ (P+0.8*S)
where,
Q* = direct runoff (inches)
S = potential abstraction = (1000/CN) - 10
P = accumulated storm rainfall (inches)
Onsite Drainage Area, A =9.72 acres
Onsite SCS CN =65
S =5.29
P (1-year/24-hour) =2.58 inches
Q* =0.34 inches
Onsite Runoff Volume =0.28 acre-ft
=11,983 cf
Project Name: Southstone Date:1/18/2018
Project Number:TAC-17000 Calculated By: J. Mattingly, EI
Subbasin ID:2-To SWMF C
SCS CURVE NUMBER
(REF: TR-55 and NRCS Web Soil Survey).
HSG Impervious Open Wooded Pond 1/2 Acre Lot 1/3 Acre Lot Right of Way
A 98 39 30 100 54 57 77
B 98 61 55 100 70 72 85
C 98 74 70 100 80 81 90
D 98 80 77 100 85 86 92
HSG 'A' =0%
HSG 'B' =29%
HSG 'C' =8%
HSG 'D' =63%
Cover Composite
Condition SCS CN
Impervious 98
Open 74
Wooded 70
Pond 100
1/2 Acre Lot 80
1/3 Acre Lot 82
Right of Way 90
ONSITE IMPERVIOUS BREAKDOWN
Imp per Lot Imp Area
# of Lots [sf][sf]
10.00 4,350 43,500
11.00 4,000 44,000
--79,031
Total Onsite Impervious Area =166,531 sf
WATERSHED BREAKDOWN
Composite Area Area
SCS CN [sf][acres]
98 166,531 3.82
74 221,598 5.09
70 0 0.00
100 16,054 0.37
98 0 0.00
80 0 0.00
82 0 0.00
90 0 0.00
74 0 0.00
70 0 0.00
100 0 0.00
Total Area =404,183 sf
=9.28 acres
Composite SCS CN =85
% Impervious =41.20%
TIME OF CONCENTRATION
(REF: SCS Segmental Approach, TR-55).
Time of Concentration =5.00 minutes
SCS Lag Time =3.00 minutes
Offsite Open Assume good condition
Offsite Wooded Assume good condition
Offsite Pond -
Offsite 1/2 Acre Lot Assume 25% impervious
Offsite 1/3 Acre Lot Assume 30% impervious
Offsite Right of Way Assume 65% Impervious
Onsite Wooded Assume good condition
Onsite Pond -
Offsite Impervious -
Onsite Open Assume good condition
Assume 25% impervious
Assume 30% impervious
Assume 65% Impervious
Contributing Area
56' x 66' Lots
50' x 65' Lots
Measured Impervious
Contributing Area Comments
Onsite Impervious -
-
POST DEVELOPMENT HYDROLOGIC CALCULATIONS
Comments
-
Assume good condition
Assume good condition
RUNOFF VOLUME CALCULATIONS
Runoff volume calculations are based upon the SCS Method
where,
Q* = direct runoff (inches)
S = potential abstraction = (1000/CN) - 10
P = accumulated storm rainfall (inches)
Onsite Drainage Area, A =9.28 acres
Onsite SCS CN =85
S =1.77
P (1-year/24-hour) =2.58 inches
Q* =1.24 inches
Onsite Runoff Volume =0.96 acre-ft
=41,689 cf
Q* = ((P-0.2*S)2)/ (P+0.8*S)
Project Name: Southstone Date:1/18/2018
Project Number:TAC-17000 Calculated By: J. Mattingly, EI
Subbasin ID:2-To SWMF D
SCS CURVE NUMBER
(REF: TR-55 and NRCS Web Soil Survey).
HSG Impervious Open Wooded Pond 1/2 Acre Lot 1/3 Acre Lot Right of Way
A 98 39 30 100 54 57 77
B 98 61 55 100 70 72 85
C 98 74 70 100 80 81 90
D 98 80 77 100 85 86 92
HSG 'A' =0%
HSG 'B' =6%
HSG 'C' =35%
HSG 'D' =59%
Cover Composite
Condition SCS CN
Impervious 98
Open 77
Wooded 73
Pond 100
1/2 Acre Lot 82
1/3 Acre Lot 83
Right of Way 91
ONSITE IMPERVIOUS BREAKDOWN
Imp per Lot Imp Area
# of Lots [sf][sf]
0.00 4,350 0
23.75 4,000 95,000
--50,932
Total Onsite Impervious Area =145,932 sf
WATERSHED BREAKDOWN
Composite Area Area
SCS CN [sf][acres]
98 145,932 3.35
77 206,033 4.73
73 22,751 0.52
100 27,944 0.64
98 0 0.00
82 143,370 3.29
83 0 0.00
91 0 0.00
77 0 0.00
73 121,062 2.78
100 0 0.00
Total Area =667,092 sf
=15.31 acres
Composite SCS CN =83
% Impervious =27.25%
TIME OF CONCENTRATION
(REF: SCS Segmental Approach, TR-55).
Time of Concentration =5.00 minutes
SCS Lag Time =3.00 minutes
Offsite Open Assume good condition
Offsite Wooded Assume good condition
Offsite Pond -
Offsite 1/2 Acre Lot Assume 25% impervious
Offsite 1/3 Acre Lot Assume 30% impervious
Offsite Right of Way Assume 65% Impervious
Onsite Wooded Assume good condition
Onsite Pond -
Offsite Impervious -
Onsite Open Assume good condition
Assume 25% impervious
Assume 30% impervious
Assume 65% Impervious
Contributing Area
56' x 66' Lots
50' x 65' Lots
Measured Impervious
Contributing Area Comments
Onsite Impervious -
-
POST DEVELOPMENT HYDROLOGIC CALCULATIONS
Comments
-
Assume good condition
Assume good condition
RUNOFF VOLUME CALCULATIONS
Runoff volume calculations are based upon the SCS Method
where,
Q* = direct runoff (inches)
S = potential abstraction = (1000/CN) - 10
P = accumulated storm rainfall (inches)
Onsite Drainage Area, A =9.24 acres
Onsite SCS CN =86
S =1.65
P (1-year/24-hour) =2.58 inches
Q* =1.30 inches
Onsite Runoff Volume =1.00 acre-ft
=43,635 cf
Q* = ((P-0.2*S)2)/ (P+0.8*S)
Project Name: Southstone Date:1/18/2018
Project Number:TAC-17000 Calculated By: J. Mattingly, EI
Subbasin ID:2-To SWMF E
SCS CURVE NUMBER
(REF: TR-55 and NRCS Web Soil Survey).
HSG Impervious Open Wooded Pond 1/2 Acre Lot 1/3 Acre Lot Right of Way
A 98 39 30 100 54 57 77
B 98 61 55 100 70 72 85
C 98 74 70 100 80 81 90
D 98 80 77 100 85 86 92
HSG 'A' =0%
HSG 'B' =8%
HSG 'C' =92%
HSG 'D' =0%
Cover Composite
Condition SCS CN
Impervious 98
Open 73
Wooded 69
Pond 100
1/2 Acre Lot 79
1/3 Acre Lot 80
Right of Way 90
ONSITE IMPERVIOUS BREAKDOWN
Imp per Lot Imp Area
# of Lots [sf][sf]
7.25 4,350 31,538
29.00 4,000 116,000
--114,449
Total Onsite Impervious Area =261,987 sf
WATERSHED BREAKDOWN
Composite Area Area
SCS CN [sf][acres]
98 261,987 6.01
73 297,022 6.82
69 92,750 2.13
100 14,583 0.33
98 4,691 0.11
79 0 0.00
80 8,861 0.20
90 0 0.00
73 23,486 0.54
69 47,499 1.09
100 0 0.00
Total Area =750,879 sf
=17.24 acres
Composite SCS CN =82
% Impervious =35.87%
TIME OF CONCENTRATION
(REF: SCS Segmental Approach, TR-55).
Time of Concentration =5.00 minutes
SCS Lag Time =3.00 minutes
Offsite Open Assume good condition
Offsite Wooded Assume good condition
Offsite Pond -
Offsite 1/2 Acre Lot Assume 25% impervious
Offsite 1/3 Acre Lot Assume 30% impervious
Offsite Right of Way Assume 65% Impervious
Onsite Wooded Assume good condition
Onsite Pond -
Offsite Impervious -
Onsite Open Assume good condition
Assume 25% impervious
Assume 30% impervious
Assume 65% Impervious
Contributing Area
56' x 66' Lots
50' x 65' Lots
Measured Impervious
Contributing Area Comments
Onsite Impervious -
-
POST DEVELOPMENT HYDROLOGIC CALCULATIONS
Comments
-
Assume good condition
Assume good condition
RUNOFF VOLUME CALCULATIONS
Runoff volume calculations are based upon the SCS Method
where,
Q* = direct runoff (inches)
S = potential abstraction = (1000/CN) - 10
P = accumulated storm rainfall (inches)
Onsite Drainage Area, A =15.30 acres
Onsite SCS CN =83
S =2.08
P (1-year/24-hour) =2.58 inches
Q* =1.11 inches
Onsite Runoff Volume =1.41 acre-ft
=61,359 cf
Q* = ((P-0.2*S)2)/ (P+0.8*S)
Project Name: Southstone Date:1/18/2018
Project Number:TAC-17000 Calculated By: J. Mattingly, EI
Subbasin ID:2-Bypass
SCS CURVE NUMBER
(REF: TR-55 and NRCS Web Soil Survey).
HSG Impervious Open Wooded Pond 1/2 Acre Lot 1/3 Acre Lot Right of Way
A 98 39 30 100 54 57 77
B 98 61 55 100 70 72 85
C 98 74 70 100 80 81 90
D 98 80 77 100 85 86 92
HSG 'A' =0%
HSG 'B' =28%
HSG 'C' =67%
HSG 'D' =6%
Cover Composite
Condition SCS CN
Impervious 99
Open 71
Wooded 67
Pond 100
1/2 Acre Lot 78
1/3 Acre Lot 80
Right of Way 90
ONSITE IMPERVIOUS BREAKDOWN
Imp per Lot Imp Area
# of Lots [sf][sf]
3.75 4,350 16,313
1.00 4,000 4,000
--0
Total Onsite Impervious Area =20,313 sf
WATERSHED BREAKDOWN
Composite Area Area
SCS CN [sf][acres]
99 20,313 0.47
71 268,897 6.17
67 108,288 2.49
100 0 0.00
99 0 0.00
78 0 0.00
80 299,089 6.87
90 83,799 1.92
71 11,955 0.27
67 67,625 1.55
100 0 0.00
Total Area =859,966 sf
=19.74 acres
Composite SCS CN =76
% Impervious =19.13%
TIME OF CONCENTRATION
(REF: SCS Segmental Approach, TR-55).
Segment 1: Overland Flow Segment 2: Concentrated Flow
Length =100 ft Length =43 ft
Upstream Elevation =626.50 ft Upstream Elevation =622.50 ft
Downstream Elevation =622.50 ft Downstream Elevation =619.50 ft
Height =4.00 ft Height =3.00 ft
Slope =0.0400 ft/ft Slope =0.0698 ft/ft
Manning's n =0.40 wooded-light underbrush Paved?No
P (2-year/24-hour) =3.51 inches (Charlotte, NC)Velocity =4.26 ft/sec
Segment Time =15.54 minutes Segment Time =0.17 minutes
Segment 3: Channel Flow
Length =172 ft
Upstream Elevation =619.50 ft
Downstream Elevation =605.00 ft
Height =14.50 ft
Slope =0.0843 ft/ft
Manning's n =0.045 natural channel
Flow Area =16 sf (assume 4'x4' channel)
Wetted Perimeter =12 lf (assume 4'x4' channel)
Channel Velocity =11.65 ft/sec
Segment Time =0.25 minutes
Time of Concentration =15.95 minutes
SCS Lag Time =9.57 minutes
Measured Impervious
Contributing Area Comments
Onsite Impervious -
56' x 66' Lots
50' x 65' Lots
POST DEVELOPMENT HYDROLOGIC CALCULATIONS
Comments
-
Assume good condition
Assume good condition
-
Assume 25% impervious
Assume 30% impervious
Assume 65% Impervious
Contributing Area
Onsite Open Assume good condition
Onsite Wooded Assume good condition
Onsite Pond -
Offsite Pond -
Offsite Impervious -
Offsite Open Assume good condition
Offsite Wooded Assume good condition
Offsite 1/2 Acre Lot Assume 25% impervious
Offsite 1/3 Acre Lot Assume 30% impervious
Offsite Right of Way Assume 65% Impervious
RUNOFF VOLUME CALCULATIONS
Runoff volume calculations are based upon the SCS Method
where,
Q* = direct runoff (inches)
S = potential abstraction = (1000/CN) - 10
P = accumulated storm rainfall (inches)
Onsite Drainage Area, A =9.13 acres
Onsite SCS CN =72
S =3.96
P (1-year/24-hour) =2.58 inches
Q* =0.56 inches
Onsite Runoff Volume =0.42 acre-ft
=18,419 cf
Q* = ((P-0.2*S)2)/ (P+0.8*S)
Project Name: Southstone Date:1/18/2018
Project Number:TAC-17000 Calculated By: J. Mattingly, EI
Subbasin ID:3
SCS CURVE NUMBER
(REF: TR-55 and NRCS Web Soil Survey).
HSG Impervious Open Wooded Pond 1/2 Acre Lot 1/3 Acre Lot Right of Way
A 98 39 30 100 54 57 77
B 98 61 55 100 70 72 85
C 98 74 70 100 80 81 90
D 98 80 77 100 85 86 92
HSG 'A' =0%
HSG 'B' =20%
HSG 'C' =73%
HSG 'D' =7%
Cover Composite
Condition SCS CN
Impervious 98
Open 72
Wooded 67
Pond 100
1/2 Acre Lot 78
1/3 Acre Lot 80
Right of Way 89
ONSITE IMPERVIOUS BREAKDOWN
Imp per Lot Imp Area
# of Lots [sf][sf]
0.00 4,350 0
0.00 4,000 0
--
Total Onsite Impervious Area =0 sf
WATERSHED BREAKDOWN
Composite Area Area
SCS CN [sf][acres]
98 0 0.00
72 24,617 0.57
67 25,887 0.59
100 0 0.00
98 854,495 19.62
78 282,086 6.48
80 1,124,430 25.81
89 511,161 11.73
72 2,321,807 53.30
67 4,858,503 111.54
100 90,025 2.07
Total Area =10,093,011 sf
=231.70 acres
Composite SCS CN =74
% Impervious =15.80%
TIME OF CONCENTRATION
(REF: SCS Segmental Approach, TR-55).
Segment 1: Overland Flow Segment 2: Concentrated Flow
Length =100 ft Length =876 ft
Upstream Elevation =736.00 ft Upstream Elevation =734.50 ft
Downstream Elevation =734.50 ft Downstream Elevation =712.00 ft
Height =1.50 ft Height =22.50 ft
Slope =0.0150 ft/ft Slope =0.0257 ft/ft
Manning's n =0.24 dense grasses Paved?No
P (2-year/24-hour) =3.51 inches (Charlotte, NC)Velocity =2.59 ft/sec
Segment Time =15.29 minutes Segment Time =5.65 minutes
Segment 3: Channel Flow Segment 4: Pipe Flow
Length =1799 ft Length =1353 ft
Upstream Elevation =712.00 ft Upstream Elevation =668.00 ft
Downstream Elevation =668.00 ft Downstream Elevation =647.00 ft
Height =44.00 ft Height =21.00 ft
Slope =0.0245 ft/ft Slope =0.0155 ft/ft
Manning's n =0.045 natural channel Manning's n =0.013 RCP
Flow Area =9 sf (assume 3'x3' channel)Flow Area =1.8 sf (assume 18" RCP)
Wetted Perimeter =9 lf (assume 3'x3' channel)Wetted Perimeter =4.7 lf (assume 18" RCP)
Channel Velocity =5.18 ft/sec Channel Velocity =7.43 ft/sec
Segment Time =5.79 minutes Segment Time =3.04 minutes
Measured Impervious
Contributing Area Comments
Onsite Impervious -
56' x 66' Lots
50' x 65' Lots
POST DEVELOPMENT HYDROLOGIC CALCULATIONS
Comments
-
Assume good condition
Assume good condition
-
Assume 25% impervious
Assume 30% impervious
Assume 65% Impervious
Contributing Area
Onsite Open Assume good condition
Onsite Wooded Assume good condition
Onsite Pond -
Offsite Pond -
Offsite Impervious -
Offsite Open Assume good condition
Offsite Wooded Assume good condition
Offsite 1/2 Acre Lot Assume 25% impervious
Offsite 1/3 Acre Lot Assume 30% impervious
Offsite Right of Way Assume 65% Impervious
Segment 5: Channel Flow Segment 6: Pipe Flow
Length =1735 ft Length =51 ft
Upstream Elevation =647.00 ft Upstream Elevation =628.00 ft
Downstream Elevation =628.00 ft Downstream Elevation =627.00 ft
Height =19.00 ft Height =1.00 ft
Slope =0.0110 ft/ft Slope =0.0196 ft/ft
Manning's n =0.045 natural channel Manning's n =0.013 RCP
Flow Area =16 sf (assume 4'x4' channel)Flow Area =1.8 sf (assume 18" RCP)
Wetted Perimeter =12 lf (assume 4'x4' channel)Wetted Perimeter =4.7 lf (assume 18" RCP)
Channel Velocity =4.20 ft/sec Channel Velocity =8.35 ft/sec
Segment Time =6.89 minutes Segment Time =0.10 minutes
Segment 7: Channel Flow
Length =1498 ft
Upstream Elevation =627.00 ft
Downstream Elevation =612.00 ft
Height =15.00 ft
Slope =0.0100 ft/ft
Manning's n =0.045 natural channel
Flow Area =16 sf (assume 4'x4' channel)
Wetted Perimeter =12 lf (assume 4'x4' channel)
Channel Velocity =4.01 ft/sec
Segment Time =6.22 minutes
Time of Concentration =42.97 minutes
SCS Lag Time =25.78 minutes
RUNOFF VOLUME CALCULATIONS
Runoff volume calculations are based upon the SCS Method
where,
Q* = direct runoff (inches)
S = potential abstraction = (1000/CN) - 10
P = accumulated storm rainfall (inches)
Onsite Drainage Area, A =1.16 acres
Onsite SCS CN =70
S =4.37
P (1-year/24-hour) =2.58 inches
Q* =0.48 inches
Onsite Runoff Volume =0.05 acre-ft
=2,016 cf
Q* = ((P-0.2*S)2)/ (P+0.8*S)
Project Name: Southstone Date:1/18/2018
Project Number:TAC-17000 Calculated By: J. Mattingly, EI
Subbasin ID:4-To SWMF F
SCS CURVE NUMBER
(REF: TR-55 and NRCS Web Soil Survey).
HSG Impervious Open Wooded Pond 1/2 Acre Lot 1/3 Acre Lot Right of Way
A 98 39 30 100 54 57 77
B 98 61 55 100 70 72 85
C 98 74 70 100 80 81 90
D 98 80 77 100 85 86 92
HSG 'A' =0%
HSG 'B' =73%
HSG 'C' =27%
HSG 'D' =0%
Cover Composite
Condition SCS CN
Impervious 98
Open 65
Wooded 59
Pond 100
1/2 Acre Lot 73
1/3 Acre Lot 74
Right of Way 86
ONSITE IMPERVIOUS BREAKDOWN
Imp per Lot Imp Area
# of Lots [sf][sf]
16.50 4,350 71,775
0.00 4,000 0
--37,722
Total Onsite Impervious Area =109,497 sf
WATERSHED BREAKDOWN
Composite Area Area
SCS CN [sf][acres]
98 109,497 2.51
65 193,423 4.44
59 26,908 0.62
100 12,685 0.29
98 775 0.02
73 0 0.00
74 48,779 1.12
86 0 0.00
65 17,475 0.40
59 182,677 4.19
100 0 0.00
Total Area =592,219 sf
=13.60 acres
Composite SCS CN =70
% Impervious =21.09%
TIME OF CONCENTRATION
(REF: SCS Segmental Approach, TR-55).
Time of Concentration =5.00 minutes
SCS Lag Time =3.00 minutes
Offsite Pond -
Contributing Area
56' x 66' Lots
50' x 65' Lots
Offsite Right of Way Assume 65% Impervious
Offsite Open Assume good condition
Offsite Wooded Assume good condition
Offsite Impervious -
Offsite 1/2 Acre Lot Assume 25% impervious
Offsite 1/3 Acre Lot Assume 30% impervious
Onsite Open Assume good condition
Onsite Wooded Assume good condition
Onsite Pond -
Onsite Impervious -
Measured Impervious
POST DEVELOPMENT HYDROLOGIC CALCULATIONS
Comments
-
Assume good condition
Assume good condition
-
Assume 25% impervious
Assume 30% impervious
Assume 65% Impervious
Contributing Area Comments
RUNOFF VOLUME CALCULATIONS
Runoff volume calculations are based upon the SCS Method
Q* = ((P-0.2*S)2)/ (P+0.8*S)
where,
Q* = direct runoff (inches)
S = potential abstraction = (1000/CN) - 10
P = accumulated storm rainfall (inches)
Onsite Drainage Area, A =7.86 acres
Onsite SCS CN =76
S =3.14
P (1-year/24-hour) =2.58 inches
Q* =0.75 inches
Onsite Runoff Volume =0.49 acre-ft
=21,356 cf
Project Name: Southstone Date:1/18/2018
Project Number:TAC-17000 Calculated By: J. Mattingly, EI
Subbasin ID:4-Bypass
SCS CURVE NUMBER
(REF: TR-55 and NRCS Web Soil Survey).
HSG Impervious Open Wooded Pond 1/2 Acre Lot 1/3 Acre Lot Right of Way
A 98 39 30 100 54 57 77
B 98 61 55 100 70 72 85
C 98 74 70 100 80 81 90
D 98 80 77 100 85 86 92
HSG 'A' =0%
HSG 'B' =5%
HSG 'C' =95%
HSG 'D' =0%
Cover Composite
Condition SCS CN
Impervious 98
Open 73
Wooded 69
Pond 100
1/2 Acre Lot 80
1/3 Acre Lot 81
Right of Way 90
ONSITE IMPERVIOUS BREAKDOWN
Imp per Lot Imp Area
# of Lots [sf][sf]
0.00 4,350 0
0.00 4,000 0
--0
Total Onsite Impervious Area =0 sf
WATERSHED BREAKDOWN
Composite Area Area
SCS CN [sf][acres]
98 0 0.00
73 80,964 1.86
69 112,605 2.59
100 0 0.00
98 44,073 1.01
80 0 0.00
81 0 0.00
90 0 0.00
73 154,689 3.55
69 241,899 5.55
100 0 0.00
Total Area =634,230 sf
=14.56 acres
Composite SCS CN =73
% Impervious =6.95%
TIME OF CONCENTRATION
(REF: SCS Segmental Approach, TR-55).
Segment 1: Overland Flow Segment 2: Concentrated Flow
Length =100 ft Length =387 ft
Upstream Elevation =671.00 ft Upstream Elevation =669.00 ft
Downstream Elevation =669.00 ft Downstream Elevation =649.00 ft
Height =2.00 ft Height =20.00 ft
Slope =0.0200 ft/ft Slope =0.0517 ft/ft
Manning's n =0.40 wooded-light underbrush Paved?No
P (2-year/24-hour) =3.51 inches (Charlotte, NC)Velocity =3.67 ft/sec
Segment Time =20.50 minutes Segment Time =1.76 minutes
Assume 25% impervious
Assume 30% impervious
Assume 65% Impervious
Offsite 1/2 Acre Lot Assume 25% impervious
-
Contributing Area
56' x 66' Lots
50' x 65' Lots
Measured Impervious
Offsite 1/3 Acre Lot Assume 30% impervious
Offsite Right of Way Assume 65% Impervious
-
Contributing Area Comments
Onsite Impervious -
Onsite Open Assume good condition
Onsite Wooded Assume good condition
Onsite Pond -
Offsite Impervious
POST DEVELOPMENT HYDROLOGIC CALCULATIONS
Comments
-
Assume good condition
Assume good condition
Offsite Open Assume good condition
Offsite Wooded Assume good condition
Offsite Pond -
Segment 3: Channel Flow Segment 4: Channel Flow
Length =464 ft Length =612 ft
Upstream Elevation =649.00 ft Upstream Elevation =634.00 ft
Downstream Elevation =634.00 ft Downstream Elevation =625.00 ft
Height =15.00 ft Height =9.00 ft
Slope =0.0323 ft/ft Slope =0.0147 ft/ft
Manning's n =0.045 natural channel Manning's n =0.045 natural channel
Flow Area =4 sf (assume 2'x2' channel)Flow Area =4 sf (assume 2'x2' channel)
Wetted Perimeter =6 lf (assume 2'x2' channel)Wetted Perimeter =6 lf (assume 2'x2' channel)
Channel Velocity =4.54 ft/sec Channel Velocity =3.06 ft/sec
Segment Time =1.70 minutes Segment Time =3.33 minutes
Time of Concentration =23.96 minutes
SCS Lag Time =14.38 minutes
RUNOFF VOLUME CALCULATIONS
Runoff volume calculations are based upon the SCS Method
Q* = ((P-0.2*S)2)/ (P+0.8*S)
where,
Q* = direct runoff (inches)
S = potential abstraction = (1000/CN) - 10
P = accumulated storm rainfall (inches)
Onsite Drainage Area, A =4.44 acres
Onsite SCS CN =71
S =4.09
P (1-year/24-hour) =2.58 inches
Q* =0.53 inches
Onsite Runoff Volume =0.20 acre-ft
=8,553 cf
Project Name: Southstone Date:1/18/2018
Project Number:TAC-17000 Calculated By: J. Mattingly, EI
Subbasin ID:Unanalyzed
SCS CURVE NUMBER
(REF: TR-55 and NRCS Web Soil Survey).
HSG Impervious Open Wooded Pond 1/2 Acre Lot 1/3 Acre Lot Right of Way
A 98 39 30 100 54 57 77
B 98 61 55 100 70 72 85
C 98 74 70 100 80 81 90
D 98 80 77 100 85 86 92
HSG 'A' =0%
HSG 'B' =100%
HSG 'C' =0%
HSG 'D' =0%
Cover Composite
Condition SCS CN
Impervious 98
Open 61
Wooded 55
Pond 100
1/2 Acre Lot 70
1/3 Acre Lot 72
Right of Way 85
ONSITE IMPERVIOUS BREAKDOWN
Imp per Lot Imp Area
# of Lots [sf][sf]
0.00 4,350 0
0.00 4,000 0
--0
Total Onsite Impervious Area =0 sf
WATERSHED BREAKDOWN
Composite Area Area
SCS CN [sf][acres]
98 0 0.00
61 48,152 1.11
55 0 0.00
100 0 0.00
98 0 0.00
70 0 0.00
72 0 0.00
85 0 0.00
61 0 0.00
55 0 0.00
100 0 0.00
Total Area =48,152 sf
=1.11 acres
Composite SCS CN =61
% Impervious =0.00%
RUNOFF VOLUME CALCULATIONS
Runoff volume calculations are based upon the SCS Method
where,
Q* = direct runoff (inches)
S = potential abstraction = (1000/CN) - 10
P = accumulated storm rainfall (inches)
Onsite Drainage Area, A =1.11 acres
Onsite SCS CN =61
S =6.39
P (1-year/24-hour) =2.58 inches
Q* =0.22 inches
Onsite Runoff Volume =0.02 acre-ft
=883 cf
Assume 25% impervious
Assume 30% impervious
Assume 65% Impervious
Offsite 1/2 Acre Lot Assume 25% impervious
-
Contributing Area
56' x 66' Lots
50' x 65' Lots
Measured Impervious
Offsite 1/3 Acre Lot Assume 30% impervious
Offsite Right of Way Assume 65% Impervious
-
Contributing Area Comments
Onsite Impervious -
Onsite Open Assume good condition
Onsite Wooded Assume good condition
Onsite Pond -
Offsite Impervious
POST DEVELOPMENT HYDROLOGIC CALCULATIONS
Comments
-
Assume good condition
Assume good condition
Q* = ((P-0.2*S)2)/ (P+0.8*S)
Offsite Open Assume good condition
Offsite Wooded Assume good condition
Offsite Pond -
Project Name: Southstone Date:1/18/2018
Project Number:TAC-17000 Calculated By: J. Mattingly, EI
Subbasin ID:Reach Data
REACH DATA
(REF: SCS Segmental Approach, TR-55).
REACH 1: POA 2 to POA 1
Length =962 ft
Upstream Elevation =605.00 ft
Downstream Elevation =598.00 ft
Height =7.00 ft
Slope =0.0073 ft/ft
Manning's n =0.045 natural channel
Flow Area =36 sf (assume 6'x6' channel)
Wetted Perimeter =18 lf (assume 6'x6' channel)
Channel Velocity =4.48 ft/sec
Segment Time =3.58 minutes
REACH 2: POA 3 to POA 2
Length =1136 ft
Upstream Elevation =612.00 ft
Downstream Elevation =605.00 ft
Height =7.00 ft
Slope =0.0062 ft/ft
Manning's n =0.045 natural channel
Flow Area =16 sf (assume 4'x4' channel)
Wetted Perimeter =12 lf (assume 4'x4' channel)
Channel Velocity =3.15 ft/sec
Segment Time =6.01 minutes
REACH 3: POA 4 to POA 2
Length =1026 ft
Upstream Elevation =625.00 ft
Downstream Elevation =605.00 ft
Height =20.00 ft
Slope =0.0195 ft/ft
Manning's n =0.045 natural channel
Flow Area =4 sf (assume 2'x2' channel)
Wetted Perimeter =6 lf (assume 2'x2' channel)
Channel Velocity =3.53 ft/sec
Segment Time =4.85 minutes
POST DEVELOPMENT HYDROLOGIC CALCULATIONS
2 BYPASS
4 BYPASS
3
2 TO SWMF D
2 TO SWMF C
1 BYPASS 1 TO SWMF B
1 TO SWMF A
2 TO SWMF E
4 TO SWMF F
SWMF D
SWMF C
SWMF B
SWMF A
SWMF E
SWMF F
REACH3
POA2
POA3
POA4
POA1
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Subsection: Master Network Summary
Catchments Summary
Peak Flow
(ft³/s)
Time to Peak
(min)
Hydrograph
Volume
(ft³)
Return
Event
(years)
ScenarioLabel
8.52716.0021,813.0001Post 1 Year1 TO SWMF A
9.78187.0016,211.0002Post 2 Year1 TO SWMF A
28.17186.0047,600.00010Post 10 Year1 TO SWMF A
37.93186.0064,496.00025Post 25 Year1 TO SWMF A
53.66186.0091,084.000100Post 100 Year1 TO SWMF A
22.35716.0053,291.0001Post 1 Year1 TO SWMF B
26.89186.0041,284.0002Post 2 Year1 TO SWMF B
63.65186.00106,000.00010Post 10 Year1 TO SWMF B
82.26186.00139,300.00025Post 25 Year1 TO SWMF B
111.80186.00190,631.000100Post 100 Year1 TO SWMF B
26.26722.0077,952.0001Post 1 Year1 BYPASS
24.96192.0057,491.0002Post 2 Year1 BYPASS
80.03190.00174,022.00010Post 10 Year1 BYPASS
109.80190.00237,364.00025Post 25 Year1 BYPASS
156.44190.00337,489.000100Post 100 Year1 BYPASS
18.08716.0041,819.0001Post 1 Year2 TO SWMF C
23.21186.0033,937.0002Post 2 Year2 TO SWMF C
44.39186.0074,538.00010Post 10 Year2 TO SWMF C
54.76186.0094,322.00025Post 25 Year2 TO SWMF C
71.00186.00124,085.000100Post 100 Year2 TO SWMF C
26.72716.0061,999.0001Post 1 Year2 TO SWMF D
33.77186.0049,694.0002Post 2 Year2 TO SWMF D
68.18186.00113,843.00010Post 10 Year2 TO SWMF D
85.16186.00145,561.00025Post 25 Year2 TO SWMF D
111.82186.00193,584.000100Post 100 Year2 TO SWMF D
28.40716.0066,094.0001Post 1 Year2 TO SWMF E
35.58186.0052,638.0002Post 2 Year2 TO SWMF E
73.94186.00123,230.00010Post 10 Year2 TO SWMF E
92.94186.00158,400.00025Post 25 Year2 TO SWMF E
122.84186.00211,828.000100Post 100 Year2 TO SWMF E
16.23725.0053,037.0001Post 1 Year2 BYPASS
16.00195.0040,588.0002Post 2 Year2 BYPASS
43.84194.00109,625.00010Post 10 Year2 BYPASS
58.19194.00145,770.00025Post 25 Year2 BYPASS
80.24193.00201,929.000100Post 100 Year2 BYPASS
86.38744.00542,256.0001Post 1 Year3
88.99218.00411,909.0002Post 2 Year3
273.75212.001,174,860.00010Post 10 Year3
372.50212.001,581,655.00025Post 25 Year3
523.41212.002,219,020.000100Post 100 Year3
9.04720.0024,356.0001Post 1 Year4 TO SWMF F
9.60187.0017,551.0002Post 2 Year4 TO SWMF F
32.92186.0056,727.00010Post 10 Year4 TO SWMF F
45.70186.0078,462.00025Post 25 Year4 TO SWMF F
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Subsection: Master Network Summary
Catchments Summary
Peak Flow
(ft³/s)
Time to Peak
(min)
Hydrograph
Volume
(ft³)
Return
Event
(years)
ScenarioLabel
66.49186.00113,141.000100Post 100 Year4 TO SWMF F
7.41729.0032,069.0001Post 1 Year4 BYPASS
7.19202.0023,988.0002Post 2 Year4 BYPASS
22.81201.0070,434.00010Post 10 Year4 BYPASS
31.12199.0095,435.00025Post 25 Year4 BYPASS
44.12198.00134,777.000100Post 100 Year4 BYPASS
Node Summary
Peak Flow
(ft³/s)
Time to Peak
(min)
Hydrograph
Volume
(ft³)
Return
Event
(years)
ScenarioLabel
102.35749.00805,310.0001Post 1 YearPOA1
106.44222.00646,865.0002Post 2 YearPOA1
359.08222.001,932,532.00010Post 10 YearPOA1
497.20217.002,620,693.00025Post 25 YearPOA1
716.65216.003,695,822.000100Post 100 YearPOA1
97.26745.00710,135.0001Post 1 YearPOA2
100.19223.00561,041.0002Post 2 YearPOA2
334.37218.001,649,052.00010Post 10 YearPOA2
463.44218.002,224,958.00025Post 25 YearPOA2
661.69213.003,123,368.000100Post 100 YearPOA2
86.38744.00542,256.0001Post 1 YearPOA3
88.99218.00411,909.0002Post 2 YearPOA3
273.75212.001,174,860.00010Post 10 YearPOA3
372.50212.001,581,655.00025Post 25 YearPOA3
523.41212.002,219,020.000100Post 100 YearPOA3
7.47729.0043,828.0001Post 1 YearPOA4
7.25202.0033,426.0002Post 2 YearPOA4
30.46201.00118,971.00010Post 10 YearPOA4
41.90201.00165,678.00025Post 25 YearPOA4
72.17198.00239,671.000100Post 100 YearPOA4
Pond Summary
Maximum
Pond Storage
(ft³)
Maximum
Water
Surface
Elevation
(ft)
Peak Flow
(ft³/s)
Time to Peak
(min)
Hydrograph
Volume
(ft³)
Return
Event
(years)
ScenarioLabel
(N/A)(N/A)9.04720.0024,356.0001Post 1 YearSWMF F (IN)
13,023.000640.040.50871.0011,759.0001Post 1 YearSWMF F
(OUT)
(N/A)(N/A)9.60187.0017,551.0002Post 2 YearSWMF F (IN)
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Subsection: Master Network Summary
Pond Summary
Maximum
Pond Storage
(ft³)
Maximum
Water
Surface
Elevation
(ft)
Peak Flow
(ft³/s)
Time to Peak
(min)
Hydrograph
Volume
(ft³)
Return
Event
(years)
ScenarioLabel
13,336.000640.070.72293.009,439.0002Post 2 YearSWMF F
(OUT)
(N/A)(N/A)32.92186.0056,727.00010Post 10 YearSWMF F (IN)
25,327.000640.917.90210.0048,537.00010Post 10 YearSWMF F
(OUT)
(N/A)(N/A)45.70186.0078,462.00025Post 25 YearSWMF F (IN)
34,746.000641.5211.24207.0070,244.00025Post 25 YearSWMF F
(OUT)
(N/A)(N/A)66.49186.00113,141.000100Post 100 YearSWMF F (IN)
43,201.000642.0428.39196.00104,894.000100Post 100 YearSWMF F
(OUT)
(N/A)(N/A)28.40716.0066,094.0001Post 1 YearSWMF E (IN)
36,886.000615.891.34823.0036,969.0001Post 1 YearSWMF E
(OUT)
(N/A)(N/A)35.58186.0052,638.0002Post 2 YearSWMF E (IN)
39,750.000616.021.52293.0034,295.0002Post 2 YearSWMF E
(OUT)
(N/A)(N/A)73.94186.00123,230.00010Post 10 YearSWMF E (IN)
81,063.000617.759.18218.00102,352.00010Post 10 YearSWMF E
(OUT)
(N/A)(N/A)92.94186.00158,400.00025Post 25 YearSWMF E (IN)
88,908.000618.0622.55202.00137,420.00025Post 25 YearSWMF E
(OUT)
(N/A)(N/A)122.84186.00211,828.000100Post 100 YearSWMF E (IN)
109,368.000618.8431.92201.00190,781.000100Post 100 YearSWMF E
(OUT)
(N/A)(N/A)8.52716.0021,813.0001Post 1 YearSWMF A (IN)
15,952.000619.370.141,440.005,860.0001Post 1 YearSWMF A
(OUT)
(N/A)(N/A)9.78187.0016,211.0002Post 2 YearSWMF A (IN)
14,888.000619.320.14364.008,821.0002Post 2 YearSWMF A
(OUT)
(N/A)(N/A)28.17186.0047,600.00010Post 10 YearSWMF A (IN)
37,098.000620.391.31295.0029,065.00010Post 10 YearSWMF A
(OUT)
(N/A)(N/A)37.93186.0064,496.00025Post 25 YearSWMF A (IN)
47,803.000620.871.95279.0045,002.00025Post 25 YearSWMF A
(OUT)
(N/A)(N/A)53.66186.0091,084.000100Post 100 YearSWMF A (IN)
61,372.000621.455.46234.0070,769.000100Post 100 YearSWMF A
(OUT)
(N/A)(N/A)22.35716.0053,291.0001Post 1 YearSWMF B (IN)
40,549.000629.380.311,440.0012,740.0001Post 1 YearSWMF B
(OUT)
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Subsection: Master Network Summary
Pond Summary
Maximum
Pond Storage
(ft³)
Maximum
Water
Surface
Elevation
(ft)
Peak Flow
(ft³/s)
Time to Peak
(min)
Hydrograph
Volume
(ft³)
Return
Event
(years)
ScenarioLabel
(N/A)(N/A)26.89186.0041,284.0002Post 2 YearSWMF B (IN)
38,357.000629.310.30365.0019,652.0002Post 2 YearSWMF B
(OUT)
(N/A)(N/A)63.65186.00106,000.00010Post 10 YearSWMF B (IN)
65,918.000630.167.29226.0080,537.00010Post 10 YearSWMF B
(OUT)
(N/A)(N/A)82.26186.00139,300.00025Post 25 YearSWMF B (IN)
84,001.000630.7010.30220.00113,514.00025Post 25 YearSWMF B
(OUT)
(N/A)(N/A)111.80186.00190,631.000100Post 100 YearSWMF B (IN)
114,457.000631.5614.63217.00164,341.000100Post 100 YearSWMF B
(OUT)
(N/A)(N/A)18.08716.0041,819.0001Post 1 YearSWMF C (IN)
27,314.000621.600.55908.0017,276.0001Post 1 YearSWMF C
(OUT)
(N/A)(N/A)23.21186.0033,937.0002Post 2 YearSWMF C (IN)
28,490.000621.660.70331.0017,704.0002Post 2 YearSWMF C
(OUT)
(N/A)(N/A)44.39186.0074,538.00010Post 10 YearSWMF C (IN)
54,903.000622.972.48260.0056,517.00010Post 10 YearSWMF C
(OUT)
(N/A)(N/A)54.76186.0094,322.00025Post 25 YearSWMF C (IN)
60,839.000623.258.76213.0076,143.00025Post 25 YearSWMF C
(OUT)
(N/A)(N/A)71.00186.00124,085.000100Post 100 YearSWMF C (IN)
67,647.000623.5622.88198.00105,796.000100Post 100 YearSWMF C
(OUT)
(N/A)(N/A)26.72716.0061,999.0001Post 1 YearSWMF D
(IN)
44,353.000629.420.631,000.0018,294.0001Post 1 YearSWMF D
(OUT)
(N/A)(N/A)33.77186.0049,694.0002Post 2 YearSWMF D
(IN)
45,004.000629.440.91361.0023,138.0002Post 2 YearSWMF D
(OUT)
(N/A)(N/A)68.18186.00113,843.00010Post 10 YearSWMF D
(IN)
68,524.000630.1310.39214.0086,746.00010Post 10 YearSWMF D
(OUT)
(N/A)(N/A)85.16186.00145,561.00025Post 25 YearSWMF D
(IN)
82,968.000630.5416.59208.00118,310.00025Post 25 YearSWMF D
(OUT)
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Subsection: Master Network Summary
Pond Summary
Maximum
Pond Storage
(ft³)
Maximum
Water
Surface
Elevation
(ft)
Peak Flow
(ft³/s)
Time to Peak
(min)
Hydrograph
Volume
(ft³)
Return
Event
(years)
ScenarioLabel
(N/A)(N/A)111.82186.00193,584.000100Post 100 YearSWMF D
(IN)
98,597.000630.9735.32198.00166,191.000100Post 100 YearSWMF D
(OUT)
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
SOUTHSTONE
TAC-17000
STORMWATER MANAGEMENT FACILITY A
DESIGN CALCULATIONS
Project Name: Southstone Date:1/18/2018
Project Number: TAC-17000 Calculated By: J. Aldridge, PE
Facility ID:SWMF A
ABOVE NORMAL POOL
Average Incremental Accumulated Calculated
Contour Stage Contour Area Contour Area Contour Vol Contour Vol Stage
[ft][ft][sf][sf][cf][cf][ft]
618.50 0.00 12,935
618.75 0.25 18,860 15,898 3,974 3,974 0.25
619.00 0.50 19,293 19,077 4,769 8,744 0.51
619.75 1.25 20,615 19,954 14,966 23,709 1.25
620.00 1.50 21,063 20,839 5,210 28,919 1.49
621.00 2.50 22,888 21,976 21,976 50,894 2.48
622.00 3.50 24,770 23,829 23,829 74,723 3.51
622.50 4.00 25,733 25,252 12,626 87,349 4.04
b =1.1092
Ks =18588
STAGE-STORAGE FUNCTION - ABOVE NORMAL POOL
y = 18588x1.1092
R² = 0.9999
0
10,000
20,000
30,000
40,000
50,000
60,000
70,000
80,000
90,000
100,000
0.00 1.00 2.00 3.00 4.00 5.00Storage(CF)Stage (feet)
Storage vs. Stage
Project Name: Southstone Date:1/18/2018
Project Number: TAC-17000 Calculated By: J. Aldridge, PE
Facility ID:SWMF A
ABOVE NORMAL POOL
Normal Water Surface Elevation =
Temporary Ponding Elevation =
Wetland Surface Area =
% of Wetland
Zone Surface Area
Deep Pool - Forebay 618.00 to 615.50 13%
Deep Pool - Non Forebay 618.00 to 615.50 7%
Shallow Water 618.50 to 618.00 43%
Temporary Inundation 619.75 to 618.50 37%
`
WETLAND ZONE CALCULATIONS
618.50
1,527
8,800
7,680
20,615
Elevation Measured Area
[ft][sf]
2,608
619.75
Project Name: Southstone Date:1/18/2018
Project Number: TAC-17000 Calculated By: J. Aldridge, PE
Facility ID:SWMF A
WATER QUALITY VOLUME
(REF: Simple Method, Schueler, 1987).
WQV = P x Rv x A / 12
where,
WQV = Water Quality Volume (acre-ft)
Rv = 0.05 + 0.009 x I, where I is % Impervious Cover
A = Area (acres)
P = Rainfall (inches)
Total Drainage Area, A =10.18 acres
Total Impervious Area =2.95 acres
% Impervious, I =28.99%
Rainfall, P =1.00 inches
Rv =0.311 acres
WQV =0.264 acre-ft
=11,488 cf
1-YEAR TREATMENT VOLUME
Pre/Post Difference in 1-Year Volume
1-Year Treatment Volume =23,750 cf
=0.545 acre-ft
ASSOCIATED DEPTH OF 1-YEAR TREATMENT VOLUME IN POND
Water Quality Volume =23,750 cf Larger of two volumes above
Ks =18588
b =1.1092
NWSE =618.50 ft
Depth of WQV in Pond =1.25 ft
=14.97 inches
Elevation =619.75 ft Spillway must be set above this elevation
WATER QUALITY VOLUME CALCULATION
Project Name: Southstone Date:1/18/2018
Project Number: TAC-17000 Calculated By: J. Aldridge, PE
Facility ID:SWMF A
DRAWDOWN DESIGN
Using falling head
Orifice Diameter =2.50 inches
Number of Orifices =1
Orifice Coefficient, Cd =0.60
Ks =18588
b =1.1092
NWSE =618.50 ft
WQV =23,750
WQV Elevation in Pond =619.75 ft
Average Incremental Incremental
WSEL Storage Siphon Flow Flow Volume Time
[ft][cf][cfs][cfs][cf][sec]
619.75 23750 0.175
619.64 21457 0.167 0.171 2,293 13,413
619.53 19188 0.158 0.162 2,269 13,994
619.42 16946 0.148 0.153 2,242 14,675
619.31 14732 0.138 0.143 2,214 15,491
619.20 12551 0.127 0.132 2,181 16,496
619.09 10407 0.115 0.121 2,144 17,778
618.98 8305 0.101 0.108 2,101 19,503
618.87 6255 0.085 0.093 2,050 22,022
618.77 4270 0.066 0.076 1,985 26,282
618.66 2375 0.035 0.050 1,895 37,773
Drawdown Time =2.29 days 2-5 day drawdown required
DRAWDOWN DESIGN
Using average head
Average Head on Orifice =0.572 ft
Orifice Coefficient, Cd =0.60
Area of Orifice =0.034 sf
Flowrate, Q =0.124 cfs
Drawdown Time =2.22 days 2-5 day drawdown required
WATER QUALITY VOLUME DRAWDOWN CALCULATION
Project Name: Southstone Date:10/30/2017
Project Number: TAC-17000 Calculated By: J. Aldridge, PE
Facility ID:SWMF A
INPUT DATA
Inside Length =4.00 ft
Inside Width =4.00 ft
Wall Thickness =6.00 in
Standard Base Length =5.00 ft
Standard Base Width =5.00 ft
Standard Base Thickness =6.00 in
Inside Height of Riser =3.30 ft
Concrete Unit Weight =142.00 pcf Unit weight of manhole concrete is 142 pcf per NC Products
Outside Diameter of Barrel =30.00 in
Drain Pipe (if present) =8.00 in
TRASH RACK DISPLACEMENT
Bottom Length / Width =7.00 ft Calculation for truncated square pyramid
Top Length / Width =1.00 ft
Height =2.00 ft
Trash Rack Displacement =38.000 cf
CONCRETE PRESENT IN RISER STRUCTURE
Riser Walls =29.700 cf
Standard Base of Riser =12.500 cf
Less Opening for Barrel =2.454 cf
Less Opening for Drain Pipe =0.175 cf
Total Concrete Less Openings =39.571 cf
Weight of Concrete =5,619 lbs
AMOUNT OF WATER DISPLACED BY RISER STRUCTURE
Displacement by Concrete =39.571 cf
Displacement by Open Air =52.800 cf
Displacement by Trash Rack =38.000 cf
Total Water Displaced =130.371 cf
Weight of Water Displaced =8,135 lbs
RISER ANTI-FLOTATION CALCULATION
AMOUNT OF CONCRETE TO ADD TO RISER STRUCTURE
Safety Factor =1.15 Recommend 1.15 or higher
Add'l Weight for Bouyancy =3,736 lbs
Bouyant Weight of Concrete =79.60 pcf
Bouyant Weight w/ SF =69.22 pcf
Add'l Concrete to Add =53.980 cf
Less Standard Base =12.500 cf
New Base Design Required =66.480 cf
ANTI FLOTATION BLOCK DESIGN CALCULATIONS
AF Block Length =8.00 ft
AF Block Width =8.00 ft
AF Block Thickness =18.00 in
AF Block Provided =96.000 cf
Total Concrete Present =123.071 cf
Total Concrete Present =17,476 lbs
Project Name:Southstone Date:1/18/2018
Project Number:TAC-17000 Calculated By:J. Aldridge, PE
Facility ID:SWMF A
DESIGN OF RIPRAP OUTLET PROTECTION
Calculations based on NY DOT method - Pages 8.06.05 through 8.06.06 in NC Erosion Control Manual.
Flow, Q10-yr =1.36 cfs
Slope =3.70 %
Pipe Diameter, Do =24 in
=2.00 feet
Number of pipes =1
Pipe separation =0.00 feet
Manning's n =0.013
Zone from graph above =2
Outlet pipe diameter =24 in Length =12.00 ft
Outlet flowrate =1.36 cfs Width =6.00 ft
Outlet velocity =6.28 ft/sec Stone diameter =6.00 in
Material =Class B Thickness =22.00 in
Zone Material Diameter Thickness Length Width
1 Class A 3 9 4 x Do 3 x Do
2 Class B 6 22 6 x Do 3 x Do
3 Class I 13 22 8 x Do 3 x Do
4 Class I 13 22 8 x Do 3 x Do
5 Class II 23 27 10 x Do 3 x Do
6 Class II 23 27 10 x Do 3 x Do
7 Study Required
RIPRAP OUTLET PROTECTION
6.28 ft/sec
0
5
10
15
20
25
0 1 2 3 4 5 6 7 8 9 10Velocity(ft/sec)Pipe diameter (ft)
Figure 8.06.b.1
Zone 1
Zone 2
Zone 3
Zone 4
Zone 5
Zone 6 Zone 7
Storm Event: 1 year 24 hrLabel: SWMF A
Return Event: 1 yearsSubsection: Elevation-Area Volume Curve
Volume (Total)
(ft³)
Volume
(ft³)
A1+A2+sqr
(A1*A2)
(ft²)
Area
(ft²)
Planimeter
(ft²)
Elevation
(ft)
0.0000.0000.0012,601.000.0618.50
3,906.0003,906.00046,877.0618,860.000.0618.75
8,675.0004,769.00057,228.2719,293.000.0619.00
23,638.00014,963.00059,851.0520,615.000.0619.75
28,848.0005,210.00062,515.8021,063.000.0620.00
50,817.00021,969.00065,907.5522,888.000.0621.00
74,640.00023,823.00071,468.4124,770.000.0622.00
87,265.00012,625.00075,749.9125,733.000.0622.50
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 1 year 24 hrLabel: SWMF A
Return Event: 1 yearsSubsection: Outlet Input Data
Requested Pond Water Surface Elevations
ft618.50Minimum (Headwater)
ft0.10Increment (Headwater)
ft622.50Maximum (Headwater)
Outlet Connectivity
E2
(ft)
E1
(ft)
OutfallDirectionOutlet IDStructure Type
622.50619.80CulvertForwardOrificeOrifice-Circular
622.50621.30CulvertForwardRiserInlet Box
622.50618.50CulvertForwardSiphonOrifice-Circular
622.50618.00TWForwardCulvertCulvert-Circular
(N/A)(N/A)TailwaterTailwater Settings
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 1 year 24 hrLabel: SWMF A
Return Event: 1 yearsSubsection: Outlet Input Data
Structure ID: Culvert
Structure Type: Culvert-Circular
1Number of Barrels
in24.00Diameter
ft27.00Length
ft27.02Length (Computed Barrel)
ft/ft0.037Slope (Computed)
Outlet Control Data
0.013Manning's n
1Ke
0Kb
0Kr
ft0.00Convergence Tolerance
Inlet Control Data
Form 1Equation Form
0.0098K
2.0000M
0.0398C
0.6700Y
1T1 ratio (HW/D)
1T2 ratio (HW/D)
-1Slope Correction Factor
Use unsubmerged inlet control 0 equation below T1 elevation.
Use submerged inlet control 0 equation above T2 elevation
In transition zone between unsubmerged and submerged inlet
control,
interpolate between flows at T1 & T2...
ft620.28T1 Elevation ft³/s15.55T1 Flow
ft620.58T2 Elevation ft³/s17.77T2 Flow
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 1 year 24 hrLabel: SWMF A
Return Event: 1 yearsSubsection: Outlet Input Data
Structure ID: Riser
Structure Type: Inlet Box
1Number of Openings
ft621.30Elevation
ft²16.0Orifice Area
1Orifice Coefficient
ft16.00Weir Length
(ft^0.5)/s3.00Weir Coefficient
1K Reverse
0Manning's n
0Kev, Charged Riser
FalseWeir Submergence
FalseOrifice H to crest
Structure ID: Siphon
Structure Type: Orifice-Circular
1Number of Openings
ft618.50Elevation
in2.50Orifice Diameter
1Orifice Coefficient
Structure ID: Orifice
Structure Type: Orifice-Circular
2Number of Openings
ft619.80Elevation
in6.00Orifice Diameter
1Orifice Coefficient
Structure ID: TW
Structure Type: TW Setup, DS Channel
Free OutfallTailwater Type
Convergence Tolerances
30Maximum Iterations
ft0.01Tailwater Tolerance
(Minimum)
ft0.50Tailwater Tolerance
(Maximum)
ft0.01Headwater Tolerance
(Minimum)
ft0.50Headwater Tolerance
(Maximum)
ft³/s0.001Flow Tolerance (Minimum)
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 1 year 24 hrLabel: SWMF A
Return Event: 1 yearsSubsection: Outlet Input Data
Convergence Tolerances
ft³/s10.000Flow Tolerance (Maximum)
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 1 year 24 hrLabel: SWMF A
Return Event: 1 yearsSubsection: Composite Rating Curve
Composite Outflow Summary
Contributing StructuresConvergence Error
(ft)
Tailwater Elevation
(ft)
Flow
(ft³/s)
Water Surface
Elevation
(ft)
(no Q:
Orifice,Riser,Siphon,Culver
t)
0.00(N/A)0.00618.50
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.01618.60
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.05618.70
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.07618.80
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.09618.90
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.10619.00
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.12619.10
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.13619.20
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.14619.30
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.15619.40
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.15619.50
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.16619.60
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.17619.70
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.18619.80
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)0.23619.90
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)0.37620.00
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)0.58620.10
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)0.83620.20
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)1.16620.30
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)1.34620.40
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)1.49620.50
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)1.63620.60
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 1 year 24 hrLabel: SWMF A
Return Event: 1 yearsSubsection: Composite Rating Curve
Composite Outflow Summary
Contributing StructuresConvergence Error
(ft)
Tailwater Elevation
(ft)
Flow
(ft³/s)
Water Surface
Elevation
(ft)
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)1.76620.70
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)1.87620.80
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)1.98620.90
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)2.09621.00
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)2.19621.10
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)2.28621.20
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)2.37621.30
Orifice,Riser,Siphon,Culver
t
0.00(N/A)3.97621.40
Orifice,Riser,Siphon,Culver
t
0.00(N/A)6.80621.50
Orifice,Riser,Siphon,Culver
t
0.00(N/A)10.45621.60
Orifice,Riser,Siphon,Culver
t
0.00(N/A)14.56621.70
Orifice,Riser,Siphon,Culver
t
0.00(N/A)19.04621.80
Orifice,Riser,Siphon,Culver
t
0.00(N/A)23.53621.90
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)25.86622.00
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)26.33622.10
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)26.80622.20
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)27.26622.30
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)27.72622.40
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)28.16622.50
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 1 year 24 hrLabel: SWMF A (IN)
Return Event: 1 yearsSubsection: Level Pool Pond Routing Summary
Infiltration
No InfiltrationInfiltration Method
(Computed)
Initial Conditions
ft618.50Elevation (Water Surface,
Initial)
ft³0.000Volume (Initial)
ft³/s0.00Flow (Initial Outlet)
ft³/s0.00Flow (Initial Infiltration)
ft³/s0.00Flow (Initial, Total)
min1.00Time Increment
Inflow/Outflow Hydrograph Summary
ft³/s8.52Flow (Peak In)min716.00Time to Peak (Flow, In)
ft³/s0.14Flow (Peak Outlet)min1,440.00Time to Peak (Flow, Outlet)
ft619.37Elevation (Water Surface,
Peak)
ft³15,951.696Volume (Peak)
Mass Balance (ft³)
ft³0.000Volume (Initial)
ft³21,813.000Volume (Total Inflow)
ft³0.000Volume (Total Infiltration)
ft³5,860.000Volume (Total Outlet
Outflow)
ft³15,943.000Volume (Retained)
ft³-10.000Volume (Unrouted)
%0.0Error (Mass Balance)
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 2 yearLabel: SWMF A (IN)
Return Event: 2 yearsSubsection: Level Pool Pond Routing Summary
Infiltration
No InfiltrationInfiltration Method
(Computed)
Initial Conditions
ft618.50Elevation (Water Surface,
Initial)
ft³0.000Volume (Initial)
ft³/s0.00Flow (Initial Outlet)
ft³/s0.00Flow (Initial Infiltration)
ft³/s0.00Flow (Initial, Total)
min1.00Time Increment
Inflow/Outflow Hydrograph Summary
ft³/s9.78Flow (Peak In)min187.00Time to Peak (Flow, In)
ft³/s0.14Flow (Peak Outlet)min364.00Time to Peak (Flow, Outlet)
ft619.32Elevation (Water Surface,
Peak)
ft³14,888.342Volume (Peak)
Mass Balance (ft³)
ft³0.000Volume (Initial)
ft³16,211.000Volume (Total Inflow)
ft³0.000Volume (Total Infiltration)
ft³8,821.000Volume (Total Outlet
Outflow)
ft³7,382.000Volume (Retained)
ft³-8.000Volume (Unrouted)
%0.0Error (Mass Balance)
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 10 yearLabel: SWMF A (IN)
Return Event: 10 yearsSubsection: Level Pool Pond Routing Summary
Infiltration
No InfiltrationInfiltration Method
(Computed)
Initial Conditions
ft618.50Elevation (Water Surface,
Initial)
ft³0.000Volume (Initial)
ft³/s0.00Flow (Initial Outlet)
ft³/s0.00Flow (Initial Infiltration)
ft³/s0.00Flow (Initial, Total)
min1.00Time Increment
Inflow/Outflow Hydrograph Summary
ft³/s28.17Flow (Peak In)min186.00Time to Peak (Flow, In)
ft³/s1.31Flow (Peak Outlet)min295.00Time to Peak (Flow, Outlet)
ft620.39Elevation (Water Surface,
Peak)
ft³37,098.058Volume (Peak)
Mass Balance (ft³)
ft³0.000Volume (Initial)
ft³47,600.000Volume (Total Inflow)
ft³0.000Volume (Total Infiltration)
ft³29,065.000Volume (Total Outlet
Outflow)
ft³18,526.000Volume (Retained)
ft³-9.000Volume (Unrouted)
%0.0Error (Mass Balance)
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 25 yearLabel: SWMF A (IN)
Return Event: 25 yearsSubsection: Level Pool Pond Routing Summary
Infiltration
No InfiltrationInfiltration Method
(Computed)
Initial Conditions
ft618.50Elevation (Water Surface,
Initial)
ft³0.000Volume (Initial)
ft³/s0.00Flow (Initial Outlet)
ft³/s0.00Flow (Initial Infiltration)
ft³/s0.00Flow (Initial, Total)
min1.00Time Increment
Inflow/Outflow Hydrograph Summary
ft³/s37.93Flow (Peak In)min186.00Time to Peak (Flow, In)
ft³/s1.95Flow (Peak Outlet)min279.00Time to Peak (Flow, Outlet)
ft620.87Elevation (Water Surface,
Peak)
ft³47,803.057Volume (Peak)
Mass Balance (ft³)
ft³0.000Volume (Initial)
ft³64,496.000Volume (Total Inflow)
ft³0.000Volume (Total Infiltration)
ft³45,002.000Volume (Total Outlet
Outflow)
ft³19,483.000Volume (Retained)
ft³-12.000Volume (Unrouted)
%0.0Error (Mass Balance)
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 100 yearLabel: SWMF A (IN)
Return Event: 100 yearsSubsection: Level Pool Pond Routing Summary
Infiltration
No InfiltrationInfiltration Method
(Computed)
Initial Conditions
ft618.50Elevation (Water Surface,
Initial)
ft³0.000Volume (Initial)
ft³/s0.00Flow (Initial Outlet)
ft³/s0.00Flow (Initial Infiltration)
ft³/s0.00Flow (Initial, Total)
min1.00Time Increment
Inflow/Outflow Hydrograph Summary
ft³/s53.66Flow (Peak In)min186.00Time to Peak (Flow, In)
ft³/s5.46Flow (Peak Outlet)min234.00Time to Peak (Flow, Outlet)
ft621.45Elevation (Water Surface,
Peak)
ft³61,372.385Volume (Peak)
Mass Balance (ft³)
ft³0.000Volume (Initial)
ft³91,084.000Volume (Total Inflow)
ft³0.000Volume (Total Infiltration)
ft³70,769.000Volume (Total Outlet
Outflow)
ft³20,304.000Volume (Retained)
ft³-11.000Volume (Unrouted)
%0.0Error (Mass Balance)
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
SOUTHSTONE
TAC-17000
STORMWATER MANAGEMENT FACILITY B
DESIGN CALCULATIONS
Project Name: Southstone Date:1/18/2018
Project Number: TAC-17000 Calculated By: J. Aldridge, PE
Facility ID:SWMF B
ABOVE NORMAL POOL
Average Incremental Accumulated Calculated
Contour Stage Contour Area Contour Area Contour Vol Contour Vol Stage
[ft][ft][sf][sf][cf][cf][ft]
628.00 0.00 26,146
628.50 0.50 29,554 27,850 13,925 13,925 0.50
629.00 1.00 30,443 29,999 14,999 28,924 0.99
630.00 2.00 32,802 31,623 31,623 60,547 1.98
631.00 3.00 35,218 34,010 34,010 94,557 2.99
632.00 4.00 37,690 36,454 36,454 131,011 4.05
633.00 5.00 40,219 38,955 38,955 169,965 5.16
b =1.0757
Ks =29097
STAGE-STORAGE FUNCTION - ABOVE NORMAL POOL
y = 29101x1.0838
R² = 0.9997
0
20,000
40,000
60,000
80,000
100,000
120,000
140,000
160,000
180,000
0.00 1.00 2.00 3.00 4.00 5.00 6.00Storage(CF)Stage (feet)
Storage vs. Stage
Project Name: Southstone Date:1/18/2018
Project Number: TAC-17000 Calculated By: J. Aldridge, PE
Facility ID:SWMF B
MAIN POOL
Average Incremental Accumulated Calculated
Contour Stage Contour Area Contour Area Contour Vol Contour Vol Stage
[ft][ft][sf][sf][cf][cf][ft]
624.00 0.00 13,372
625.00 1.00 14,931 14,152 14,152 14,152 1.01
626.00 2.00 16,115 15,523 15,523 29,675 1.98
627.00 3.00 17,325 16,720 16,720 46,395 2.98
627.50 3.50 17,939 17,632 8,816 55,211 3.50
628.00 4.00 19,481 18,710 9,355 64,566 4.04
b =1.0921
Ks =14062
STAGE-STORAGE FUNCTION - BELOW NORMAL POOL
y = 14062x1.0921
R² = 0.9998
0
10,000
20,000
30,000
40,000
50,000
60,000
70,000
0.00 1.00 2.00 3.00 4.00 5.00Storage(CF)Stage (feet)
Storage vs. Stage
WEST FOREBAY
Average Incremental Accumulated Calculated
Contour Stage Contour Area Contour Area Contour Vol Contour Vol Stage
[ft][ft][sf][sf][cf][cf][ft]
624.00 0.00 1,645
625.00 1.00 1,985 1,815 1,815 1,815 1.01
626.00 2.00 2,351 2,168 2,168 3,983 1.96
627.00 3.00 2,742 2,547 2,547 6,530 2.97
627.50 3.50 2,947 2,845 1,422 7,952 3.50
628.00 4.00 3,400 3,174 1,587 9,539 4.08
b =1.1913
Ks =1788
y = 1787.8x1.1913
R² = 0.9991
0
2,000
4,000
6,000
8,000
10,000
12,000
0.00 1.00 2.00 3.00 4.00 5.00Storage(CF)Stage (feet)
Storage vs. Stage
EAST FOREBAY
Average Incremental Accumulated Calculated
Contour Stage Contour Area Contour Area Contour Vol Contour Vol Stage
[ft][ft][sf][sf][cf][cf][ft]
624.00 0.00 1,517
625.00 1.00 1,836 1,677 1,677 1,677 0.95
626.00 2.00 2,180 2,008 2,008 3,685 1.84
627.00 3.00 2,549 2,365 2,365 6,049 2.78
627.50 3.50 2,743 2,646 1,323 7,372 3.28
628.00 4.00 3,266 3,005 1,502 8,874 3.84
b =1.1955
Ks =1650
y = 1650.2x1.1955
R² = 0.999
0
1,000
2,000
3,000
4,000
5,000
6,000
7,000
8,000
9,000
10,000
0.00 1.00 2.00 3.00 4.00 5.00Storage(CF)Stage (feet)
Storage vs. Stage
Project Name: Southstone Date:1/18/2018
Project Number: TAC-17000 Calculated By: J. Aldridge, PE
Facility ID:SWMF B
TOTAL VOLUME
Volume of Main Pool =64,566 cf
Volume of Forebays =18,413 cf
Total Volume Below NWSE =82,978 cf
=1.90 acre-ft
Total Volume Above NWSE =169,965 cf
=3.90 acre-ft
Total Volume of Facility =252,944 cf
=5.81 acre-ft
FOREBAY CALCULATION
Total Volume Below NWSE =82,978 cf
Volume of Forebays =18,413 cf
% Forebay =22%Forebay volume should be approximately 20%
AVERAGE DEPTH OF POND
Total Volume Below NWSE =82,978 cf
Surface Area at NWSE =26,146 sf
Average Depth =3.17 Average depth must be greater than 3.0
VOLUME CALCULATIONS
Project Name: Southstone Date:1/18/2018
Project Number: TAC-17000 Calculated By: J. Aldridge, PE
Facility ID:SWMF B
DRAINAGE CHARACTERISTICS
Total Drainage Area =17.49 acres
Total Impervious Area =6.59 acres Include both onsite and offsite impervious area
% Impervious =37.68%
DETERMINATION OF REQUIRED SURFACE AREA
(REF: NCDWQ BMP Handbook, 2007).
Average Depth =3.17 ft
TSS Removal =85%
SA/DA table for Piedmont/Mountain region
3
30.0%1.34
37.7%1.64
40.0%1.73
SA/DA required =1.64
Surface Area Required =12,490 ft
=0.29 acres
Surface Area Provided =26,146 ft
SURFACE AREA CALCULATION
Lower Boundary
% Impervious
Upper Boundary
Average Depth
Project Name: Southstone Date:1/18/2018
Project Number: TAC-17000 Calculated By: J. Aldridge, PE
Facility ID:SWMF B
WATER QUALITY VOLUME
(REF: Simple Method, Schueler, 1987).
WQV = P x Rv x A / 12
where,
WQV = Water Quality Volume (acre-ft)
Rv = 0.05 + 0.009 x I, where I is % Impervious Cover
A = Area (acres)
P = Rainfall (inches)
Total Drainage Area, A =17.49 acres
Total Impervious Area =6.59 acres
% Impervious, I =37.68%
Rainfall, P =1.00 inches
Rv =0.389 acres
WQV =0.567 acre-ft
=24,704 cf
1-YEAR TREATMENT VOLUME
Pre/Post Difference in 1-Year Volume
1-Year Treatment Volume =37,472 cf
=0.860 acre-ft
ASSOCIATED DEPTH OF 1-YEAR TREATMENT VOLUME IN POND
Water Quality Volume =37,472 cf Larger of two volumes above
Ks =29097
b =1.0757
NWSE =628.00 ft
Depth of WQV in Pond =1.27 ft
=15.18 inches
Elevation =629.27 ft Spillway must be set above this elevation
WATER QUALITY VOLUME CALCULATION
Project Name: Southstone Date:1/18/2018
Project Number: TAC-17000 Calculated By: J. Aldridge, PE
Facility ID:SWMF B
DRAWDOWN DESIGN
Using falling head
Orifice Diameter =3.25 inches
Number of Orifices =1
Orifice Coefficient, Cd =0.60
Ks =29097
b =1.0757
NWSE =628.00 ft
WQV =37,472
WQV Elevation in Pond =629.27 ft
Average Incremental Incremental
WSEL Storage Siphon Flow Flow Volume Time
[ft][cf][cfs][cfs][cf][sec]
629.27 37472 0.294
629.15 33927 0.279 0.287 3,545 12,355
629.04 30408 0.264 0.272 3,519 12,958
628.93 26918 0.247 0.255 3,490 13,672
628.82 23459 0.229 0.238 3,459 14,538
628.71 20036 0.209 0.219 3,423 15,620
628.60 16654 0.188 0.199 3,382 17,031
628.48 13320 0.163 0.176 3,334 18,985
628.37 10044 0.135 0.149 3,276 21,974
628.26 6843 0.096 0.116 3,201 27,702
628.15 3747 0.042 0.069 3,096 44,858
Drawdown Time =2.31 days 2-5 day drawdown required
DRAWDOWN DESIGN
Using average head
Average Head on Orifice =0.565 inches
Orifice Coefficient, Cd =0.60
Area of Orifice =0.058 sf
Flowrate, Q =0.208 cfs
Drawdown Time =2.08 days 2-5 day drawdown required
WATER QUALITY VOLUME DRAWDOWN CALCULATION
Project Name: Southstone Date:10/19/2017
Project Number: TAC-17000 Calculated By: J. Aldridge, PE
Facility ID:SWMF B
INPUT DATA
Inside Length =4.00 ft
Inside Width =4.00 ft
Wall Thickness =6.00 in
Standard Base Length =5.00 ft
Standard Base Width =5.00 ft
Standard Base Thickness =6.00 in
Inside Height of Riser =6.00 ft
Concrete Unit Weight =142.00 pcf Unit weight of manhole concrete is 142 pcf per NC Products
Outside Diameter of Barrel =30.00 in
Drain Pipe (if present) =8.00 in
TRASH RACK DISPLACEMENT
Bottom Length / Width =7.00 ft Calculation for truncated square pyramid
Top Length / Width =1.00 ft
Height =2.00 ft
Trash Rack Displacement =38.000 cf
CONCRETE PRESENT IN RISER STRUCTURE
Riser Walls =54.000 cf
Standard Base of Riser =12.500 cf
Less Opening for Barrel =2.454 cf
Less Opening for Drain Pipe =0.175 cf
Total Concrete Less Openings =63.871 cf
Weight of Concrete =9,070 lbs
AMOUNT OF WATER DISPLACED BY RISER STRUCTURE
Displacement by Concrete =63.871 cf
Displacement by Open Air =96.000 cf
Displacement by Trash Rack =38.000 cf
Total Water Displaced =197.871 cf
Weight of Water Displaced =12,347 lbs
RISER ANTI-FLOTATION CALCULATION
AMOUNT OF CONCRETE TO ADD TO RISER STRUCTURE
Safety Factor =1.15 Recommend 1.15 or higher
Add'l Weight for Bouyancy =5,130 lbs
Bouyant Weight of Concrete =79.60 pcf
Bouyant Weight w/ SF =69.22 pcf
Add'l Concrete to Add =74.108 cf
Less Standard Base =12.500 cf
New Base Design Required =86.608 cf
ANTI FLOTATION BLOCK DESIGN CALCULATIONS
AF Block Length =8.00 ft
AF Block Width =8.00 ft
AF Block Thickness =18.00 in
AF Block Provided =96.000 cf
Total Concrete Present =147.371 cf
Total Concrete Present =20,927 lbs
Project Name:Southstone Date:1/18/2018
Project Number:TAC-17000 Calculated By:J. Aldridge, PE
Facility ID:SWMF B
DESIGN OF RIPRAP OUTLET PROTECTION
Calculations based on NY DOT method - Pages 8.06.05 through 8.06.06 in NC Erosion Control Manual.
Flow, Q10-yr =7.29 cfs
Slope =0.88 %
Pipe Diameter, Do =24 in
=2.00 feet
Number of pipes =1
Pipe separation =0.00 feet
Manning's n =0.013
Zone from graph above =2
Outlet pipe diameter =24 in Length =12.00 ft
Outlet flowrate =7.29 cfs Width =6.00 ft
Outlet velocity =6.14 ft/sec Stone diameter =6.00 in
Material =Class B Thickness =22.00 in
Zone Material Diameter Thickness Length Width
1 Class A 3 9 4 x Do 3 x Do
2 Class B 6 22 6 x Do 3 x Do
3 Class I 13 22 8 x Do 3 x Do
4 Class I 13 22 8 x Do 3 x Do
5 Class II 23 27 10 x Do 3 x Do
6 Class II 23 27 10 x Do 3 x Do
7 Study Required
RIPRAP OUTLET PROTECTION
6.14 ft/sec
0
5
10
15
20
25
0 1 2 3 4 5 6 7 8 9 10Velocity(ft/sec)Pipe diameter (ft)
Figure 8.06.b.1
Zone 1
Zone 2
Zone 3
Zone 4
Zone 5
Zone 6 Zone 7
Storm Event: 1 year 24 hrLabel: SWMF B
Return Event: 1 yearsSubsection: Elevation-Area Volume Curve
Volume (Total)
(ft³)
Volume
(ft³)
A1+A2+sqr
(A1*A2)
(acres)
Area
(acres)
Planimeter
(ft²)
Elevation
(ft)
0.0000.0000.000.600.0628.00
13,916.00013,916.0001.920.680.0628.50
28,915.00014,999.0002.070.700.0629.00
60,530.00031,615.0002.180.750.0630.00
94,533.00034,003.0002.340.810.0631.00
130,980.00036,447.0002.510.870.0632.00
169,928.00038,948.0002.680.920.0633.00
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 1 year 24 hrLabel: SWMF B
Return Event: 1 yearsSubsection: Outlet Input Data
Requested Pond Water Surface Elevations
ft628.00Minimum (Headwater)
ft0.10Increment (Headwater)
ft633.00Maximum (Headwater)
Outlet Connectivity
E2
(ft)
E1
(ft)
OutfallDirectionOutlet IDStructure Type
633.00622.00TWForwardSiphonOrifice-Circular
633.00631.00CulvertForwardRiserInlet Box
633.00628.40CulvertForwardOrificeOrifice-Circular
633.00626.00TWForwardCulvertCulvert-Circular
(N/A)(N/A)TailwaterTailwater Settings
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 1 year 24 hrLabel: SWMF B
Return Event: 1 yearsSubsection: Outlet Input Data
Structure ID: Culvert
Structure Type: Culvert-Circular
1Number of Barrels
in24.00Diameter
ft57.00Length
ft57.00Length (Computed Barrel)
ft/ft0.009Slope (Computed)
Outlet Control Data
0.013Manning's n
1Ke
0Kb
0Kr
ft0.00Convergence Tolerance
Inlet Control Data
Form 1Equation Form
0.0098K
2.0000M
0.0398C
0.6700Y
1T1 ratio (HW/D)
1T2 ratio (HW/D)
-1Slope Correction Factor
Use unsubmerged inlet control 0 equation below T1 elevation.
Use submerged inlet control 0 equation above T2 elevation
In transition zone between unsubmerged and submerged inlet
control,
interpolate between flows at T1 & T2...
ft627.81T1 Elevation ft³/s15.55T1 Flow
ft628.10T2 Elevation ft³/s17.77T2 Flow
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 1 year 24 hrLabel: SWMF B
Return Event: 1 yearsSubsection: Outlet Input Data
Structure ID: Riser
Structure Type: Inlet Box
1Number of Openings
ft631.50Elevation
ft²16.0Orifice Area
1Orifice Coefficient
ft16.00Weir Length
(ft^0.5)/s3.00Weir Coefficient
1K Reverse
0Manning's n
0Kev, Charged Riser
FalseWeir Submergence
FalseOrifice H to crest
Structure ID: Siphon
Structure Type: Orifice-Circular
1Number of Openings
ft628.00Elevation
in3.25Orifice Diameter
1Orifice Coefficient
Structure ID: Orifice
Structure Type: Orifice-Area
2Number of Openings
ft629.40Elevation
ft²1.0Orifice Area
ft629.90Top Elevation
ft629.65Datum Elevation
1Orifice Coefficient
Structure ID: TW
Structure Type: TW Setup, DS Channel
Free OutfallTailwater Type
Convergence Tolerances
30Maximum Iterations
ft0.01Tailwater Tolerance
(Minimum)
ft0.50Tailwater Tolerance
(Maximum)
ft0.01Headwater Tolerance
(Minimum)
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 1 year 24 hrLabel: SWMF B
Return Event: 1 yearsSubsection: Outlet Input Data
Convergence Tolerances
ft0.50Headwater Tolerance
(Maximum)
ft³/s0.001Flow Tolerance (Minimum)
ft³/s10.000Flow Tolerance (Maximum)
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 1 year 24 hrLabel: SWMF B
Return Event: 1 yearsSubsection: Composite Rating Curve
Composite Outflow Summary
Contributing StructuresConvergence Error
(ft)
Tailwater Elevation
(ft)
Flow
(ft³/s)
Water Surface
Elevation
(ft)
(no Q:
Riser,Orifice,Culvert,Sipho
n)
0.00(N/A)0.00628.00
Siphon (no Q:
Riser,Orifice,Culvert)
0.00(N/A)0.02628.10
Siphon (no Q:
Riser,Orifice,Culvert)
0.00(N/A)0.06628.20
Siphon (no Q:
Riser,Orifice,Culvert)
0.00(N/A)0.11628.30
Siphon (no Q:
Riser,Orifice,Culvert)
0.00(N/A)0.14628.40
Siphon (no Q:
Riser,Orifice,Culvert)
0.00(N/A)0.17628.50
Siphon (no Q:
Riser,Orifice,Culvert)
0.00(N/A)0.19628.60
Siphon (no Q:
Riser,Orifice,Culvert)
0.00(N/A)0.21628.70
Siphon (no Q:
Riser,Orifice,Culvert)
0.00(N/A)0.23628.80
Siphon (no Q:
Riser,Orifice,Culvert)
0.00(N/A)0.24628.90
Siphon (no Q:
Riser,Orifice,Culvert)
0.00(N/A)0.26629.00
Siphon (no Q:
Riser,Orifice,Culvert)
0.00(N/A)0.27629.10
Siphon (no Q:
Riser,Orifice,Culvert)
0.00(N/A)0.29629.20
Siphon (no Q:
Riser,Orifice,Culvert)
0.00(N/A)0.30629.30
Siphon (no Q:
Riser,Orifice,Culvert)
0.00(N/A)0.31629.40
Orifice,Culvert,Siphon
(no Q: Riser)
0.00(N/A)1.29629.50
Orifice,Culvert,Siphon
(no Q: Riser)
0.00(N/A)2.26629.60
Orifice,Culvert,Siphon
(no Q: Riser)
0.00(N/A)3.24629.70
Orifice,Culvert,Siphon
(no Q: Riser)
0.00(N/A)4.21629.80
Orifice,Culvert,Siphon
(no Q: Riser)
0.00(N/A)5.18629.90
Orifice,Culvert,Siphon
(no Q: Riser)
0.00(N/A)6.08630.00
Orifice,Culvert,Siphon
(no Q: Riser)
0.00(N/A)6.85630.10
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 1 year 24 hrLabel: SWMF B
Return Event: 1 yearsSubsection: Composite Rating Curve
Composite Outflow Summary
Contributing StructuresConvergence Error
(ft)
Tailwater Elevation
(ft)
Flow
(ft³/s)
Water Surface
Elevation
(ft)
Orifice,Culvert,Siphon
(no Q: Riser)
0.00(N/A)7.54630.20
Orifice,Culvert,Siphon
(no Q: Riser)
0.00(N/A)8.17630.30
Orifice,Culvert,Siphon
(no Q: Riser)
0.00(N/A)8.75630.40
Orifice,Culvert,Siphon
(no Q: Riser)
0.00(N/A)9.30630.50
Orifice,Culvert,Siphon
(no Q: Riser)
0.00(N/A)9.82630.60
Orifice,Culvert,Siphon
(no Q: Riser)
0.00(N/A)10.31630.70
Orifice,Culvert,Siphon
(no Q: Riser)
0.00(N/A)10.77630.80
Orifice,Culvert,Siphon
(no Q: Riser)
0.00(N/A)11.22630.90
Orifice,Culvert,Siphon
(no Q: Riser)
0.00(N/A)11.66631.00
Orifice,Culvert,Siphon
(no Q: Riser)
0.00(N/A)12.07631.10
Orifice,Culvert,Siphon
(no Q: Riser)
0.00(N/A)12.48631.20
Orifice,Culvert,Siphon
(no Q: Riser)
0.00(N/A)12.85631.30
Orifice,Culvert,Siphon
(no Q: Riser)
0.00(N/A)13.24631.40
Orifice,Culvert,Siphon
(no Q: Riser)
0.00(N/A)13.60631.50
Riser,Orifice,Culvert,Sipho
n
0.00(N/A)15.48631.60
Riser,Orifice,Culvert,Sipho
n
0.00(N/A)18.60631.70
Riser,Orifice,Culvert,Sipho
n
0.00(N/A)22.54631.80
Riser,Orifice,Culvert,Sipho
n
0.00(N/A)27.07631.90
Riser,Orifice,Culvert,Sipho
n
0.00(N/A)29.98632.00
Riser,Orifice,Culvert,Sipho
n
0.00(N/A)32.80632.10
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 1 year 24 hrLabel: SWMF B
Return Event: 1 yearsSubsection: Composite Rating Curve
Composite Outflow Summary
Contributing StructuresConvergence Error
(ft)
Tailwater Elevation
(ft)
Flow
(ft³/s)
Water Surface
Elevation
(ft)
Riser,Orifice,Culvert,Sipho
n
0.00(N/A)35.37632.20
Riser,Orifice,Culvert,Sipho
n
0.00(N/A)37.20632.30
Riser,Culvert,Siphon (no
Q: Orifice)
0.00(N/A)37.74632.40
Riser,Culvert,Siphon (no
Q: Orifice)
0.00(N/A)38.07632.50
Riser,Culvert,Siphon (no
Q: Orifice)
0.00(N/A)38.41632.60
Riser,Culvert,Siphon (no
Q: Orifice)
0.00(N/A)38.74632.70
Riser,Culvert,Siphon (no
Q: Orifice)
0.00(N/A)39.07632.80
Riser,Culvert,Siphon (no
Q: Orifice)
0.00(N/A)39.40632.90
Riser,Culvert,Siphon (no
Q: Orifice)
0.00(N/A)39.72633.00
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 1 year 24 hrLabel: SWMF B (IN)
Return Event: 1 yearsSubsection: Level Pool Pond Routing Summary
Infiltration
No InfiltrationInfiltration Method
(Computed)
Initial Conditions
ft628.00Elevation (Water Surface,
Initial)
ft³0.000Volume (Initial)
ft³/s0.00Flow (Initial Outlet)
ft³/s0.00Flow (Initial Infiltration)
ft³/s0.00Flow (Initial, Total)
min1.00Time Increment
Inflow/Outflow Hydrograph Summary
ft³/s22.35Flow (Peak In)min716.00Time to Peak (Flow, In)
ft³/s0.31Flow (Peak Outlet)min1,440.00Time to Peak (Flow, Outlet)
ft629.38Elevation (Water Surface,
Peak)
ft³40,548.984Volume (Peak)
Mass Balance (ft³)
ft³0.000Volume (Initial)
ft³53,291.000Volume (Total Inflow)
ft³0.000Volume (Total Infiltration)
ft³12,740.000Volume (Total Outlet
Outflow)
ft³40,530.000Volume (Retained)
ft³-21.000Volume (Unrouted)
%0.0Error (Mass Balance)
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 2 yearLabel: SWMF B (IN)
Return Event: 2 yearsSubsection: Level Pool Pond Routing Summary
Infiltration
No InfiltrationInfiltration Method
(Computed)
Initial Conditions
ft628.00Elevation (Water Surface,
Initial)
ft³0.000Volume (Initial)
ft³/s0.00Flow (Initial Outlet)
ft³/s0.00Flow (Initial Infiltration)
ft³/s0.00Flow (Initial, Total)
min1.00Time Increment
Inflow/Outflow Hydrograph Summary
ft³/s26.89Flow (Peak In)min186.00Time to Peak (Flow, In)
ft³/s0.30Flow (Peak Outlet)min365.00Time to Peak (Flow, Outlet)
ft629.31Elevation (Water Surface,
Peak)
ft³38,356.853Volume (Peak)
Mass Balance (ft³)
ft³0.000Volume (Initial)
ft³41,284.000Volume (Total Inflow)
ft³0.000Volume (Total Infiltration)
ft³19,652.000Volume (Total Outlet
Outflow)
ft³21,616.000Volume (Retained)
ft³-15.000Volume (Unrouted)
%0.0Error (Mass Balance)
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 10 yearLabel: SWMF B (IN)
Return Event: 10 yearsSubsection: Level Pool Pond Routing Summary
Infiltration
No InfiltrationInfiltration Method
(Computed)
Initial Conditions
ft628.00Elevation (Water Surface,
Initial)
ft³0.000Volume (Initial)
ft³/s0.00Flow (Initial Outlet)
ft³/s0.00Flow (Initial Infiltration)
ft³/s0.00Flow (Initial, Total)
min1.00Time Increment
Inflow/Outflow Hydrograph Summary
ft³/s63.65Flow (Peak In)min186.00Time to Peak (Flow, In)
ft³/s7.29Flow (Peak Outlet)min226.00Time to Peak (Flow, Outlet)
ft630.16Elevation (Water Surface,
Peak)
ft³65,918.215Volume (Peak)
Mass Balance (ft³)
ft³0.000Volume (Initial)
ft³106,000.000Volume (Total Inflow)
ft³0.000Volume (Total Infiltration)
ft³80,537.000Volume (Total Outlet
Outflow)
ft³25,447.000Volume (Retained)
ft³-16.000Volume (Unrouted)
%0.0Error (Mass Balance)
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 25 yearLabel: SWMF B (IN)
Return Event: 25 yearsSubsection: Level Pool Pond Routing Summary
Infiltration
No InfiltrationInfiltration Method
(Computed)
Initial Conditions
ft628.00Elevation (Water Surface,
Initial)
ft³0.000Volume (Initial)
ft³/s0.00Flow (Initial Outlet)
ft³/s0.00Flow (Initial Infiltration)
ft³/s0.00Flow (Initial, Total)
min1.00Time Increment
Inflow/Outflow Hydrograph Summary
ft³/s82.26Flow (Peak In)min186.00Time to Peak (Flow, In)
ft³/s10.30Flow (Peak Outlet)min220.00Time to Peak (Flow, Outlet)
ft630.70Elevation (Water Surface,
Peak)
ft³84,000.874Volume (Peak)
Mass Balance (ft³)
ft³0.000Volume (Initial)
ft³139,300.000Volume (Total Inflow)
ft³0.000Volume (Total Infiltration)
ft³113,514.000Volume (Total Outlet
Outflow)
ft³25,771.000Volume (Retained)
ft³-15.000Volume (Unrouted)
%0.0Error (Mass Balance)
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 100 yearLabel: SWMF B (IN)
Return Event: 100 yearsSubsection: Level Pool Pond Routing Summary
Infiltration
No InfiltrationInfiltration Method
(Computed)
Initial Conditions
ft628.00Elevation (Water Surface,
Initial)
ft³0.000Volume (Initial)
ft³/s0.00Flow (Initial Outlet)
ft³/s0.00Flow (Initial Infiltration)
ft³/s0.00Flow (Initial, Total)
min1.00Time Increment
Inflow/Outflow Hydrograph Summary
ft³/s111.80Flow (Peak In)min186.00Time to Peak (Flow, In)
ft³/s14.63Flow (Peak Outlet)min217.00Time to Peak (Flow, Outlet)
ft631.56Elevation (Water Surface,
Peak)
ft³114,456.823Volume (Peak)
Mass Balance (ft³)
ft³0.000Volume (Initial)
ft³190,631.000Volume (Total Inflow)
ft³0.000Volume (Total Infiltration)
ft³164,341.000Volume (Total Outlet
Outflow)
ft³26,274.000Volume (Retained)
ft³-16.000Volume (Unrouted)
%0.0Error (Mass Balance)
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
SOUTHSTONE
TAC-17000
STORMWATER MANAGEMENT FACILITY C
DESIGN CALCULATIONS
Project Name: Southstone Date:1/18/2018
Project Number: TAC-17000 Calculated By: J. Aldridge, PE
Facility ID:SWMF C
ABOVE NORMAL POOL
Average Incremental Accumulated Calculated
Contour Stage Contour Area Contour Area Contour Vol Contour Vol Stage
[ft][ft][sf][sf][cf][cf][ft]
620.00 0.00 11,109
620.25 0.25 16,481 13,795 3,449 3,449 0.25
621.00 1.00 17,786 17,134 12,850 16,299 1.00
621.25 1.25 18,228 18,007 4,502 20,801 1.24
622.00 2.00 19,576 18,902 14,177 34,977 1.97
623.00 3.00 21,422 20,499 20,499 55,476 2.97
624.00 4.00 23,324 22,373 22,373 77,849 4.01
625.00 5.00 25,283 24,304 24,304 102,153 5.10
b =1.1268
Ks =16286
STAGE-STORAGE FUNCTION - ABOVE NORMAL POOL
y = 16286x1.1268
R² = 0.9999
0
20,000
40,000
60,000
80,000
100,000
120,000
0.00 1.00 2.00 3.00 4.00 5.00 6.00Storage(CF)Stage (feet)
Storage vs. Stage
Project Name: Southstone Date:1/18/2018
Project Number: TAC-17000 Calculated By: J. Aldridge, PE
Facility ID:SWMF C
ABOVE NORMAL POOL
Normal Water Surface Elevation =
Temporary Ponding Elevation =
Wetland Surface Area =
% of Wetland
Zone Surface Area
Deep Pool - Forebay 619.50 to 617.00 18%
Deep Pool - Non Forebay 619.50 to 617.00 6%
Shallow Water 620.00 to 619.50 38%
Temporary Inundation 621.25 to 620.00 39%
`
7,120
WETLAND ZONE CALCULATIONS
620.00
621.25
18,228
Elevation Measured Area
[ft][sf]
3,203
1,070
6,836
Project Name: Southstone Date:1/18/2018
Project Number: TAC-17000 Calculated By: J. Aldridge, PE
Facility ID:SWMF C
1-INCH TREATMENT VOLUME
(REF: Simple Method, Schueler, 1987).
WQV = P x Rv x A / 12
where,
WQV = Water Quality Volume (acre-ft)
Rv = 0.05 + 0.009 x I, where I is % Impervious Cover
A = Area (acres)
P = Rainfall (inches)
Total Drainage Area, A =9.28 acres
Total Impervious Area =3.82 acres
% Impervious, I =41.20%
Rainfall, P =1.00 inches
Rv =0.421 acres
WQV =0.325 acre-ft
=14,174 cf
1-YEAR TREATMENT VOLUME
Pre/Post Difference in 1-Year Volume
1-Year Treatment Volume =20,227 cf
=0.464 acre-ft
ASSOCIATED DEPTH OF 1-YEAR TREATMENT VOLUME IN POND
Water Quality Volume =20,227 cf Larger of two volumes above
Ks =16286
b =1.1268
NWSE =620.00 ft
Depth of WQV in Pond =1.21 ft
=14.54 inches
Elevation =621.21 ft Spillway must be set above this elevation
WATER QUALITY VOLUME CALCULATION
Project Name: Southstone Date:1/18/2018
Project Number: TAC-17000 Calculated By: J. Aldridge, PE
Facility ID:SWMF C
DRAWDOWN DESIGN
Using falling head
Orifice Diameter =2.25 inches
Number of Orifices =1
Orifice Coefficient, Cd =0.60
Ks =16286
b =1.1268
NWSE =620.00 ft
WQV =20,227
WQV Elevation in Pond =621.21 ft
Average Incremental Incremental
WSEL Storage Siphon Flow Flow Volume Time
[ft][cf][cfs][cfs][cf][sec]
621.21 20227 0.140
621.11 18254 0.134 0.137 1,973 14,400
621.00 16305 0.126 0.130 1,949 14,990
620.90 14382 0.119 0.123 1,923 15,678
620.79 12488 0.111 0.115 1,894 16,500
620.68 10626 0.102 0.106 1,862 17,505
620.58 8799 0.092 0.097 1,826 18,780
620.47 7015 0.082 0.087 1,784 20,478
620.37 5281 0.070 0.076 1,734 22,922
620.26 3609 0.055 0.062 1,672 26,950
620.16 2023 0.031 0.043 1,586 36,985
Drawdown Time =2.37 days 2-5 day drawdown required
DRAWDOWN DESIGN
Using average head
Average Head on Orifice =0.559 inches
Orifice Coefficient, Cd =0.60
Area of Orifice =0.028 sf
Flowrate, Q =0.099 cfs
Drawdown Time =2.35 days 2-5 day drawdown required
WATER QUALITY VOLUME DRAWDOWN CALCULATION
Project Name: Southstone Date:10/19/2017
Project Number: TAC-17000 Calculated By: J. Aldridge, PE
Facility ID:SWMF C
INPUT DATA
Inside Length =4.00 ft
Inside Width =4.00 ft
Wall Thickness =6.00 in
Standard Base Length =5.00 ft
Standard Base Width =5.00 ft
Standard Base Thickness =6.00 in
Inside Height of Riser =6.50 ft
Concrete Unit Weight =142.00 pcf Unit weight of manhole concrete is 142 pcf per NC Products
Outside Diameter of Barrel =30.00 in
Drain Pipe (if present) =8.00 in
TRASH RACK DISPLACEMENT
Bottom Length / Width =7.00 ft Calculation for truncated square pyramid
Top Length / Width =1.00 ft
Height =2.00 ft
Trash Rack Displacement =38.000 cf
CONCRETE PRESENT IN RISER STRUCTURE
Riser Walls =58.500 cf
Standard Base of Riser =12.500 cf
Less Opening for Barrel =2.454 cf
Less Opening for Drain Pipe =0.175 cf
Total Concrete Less Openings =68.371 cf
Weight of Concrete =9,709 lbs
AMOUNT OF WATER DISPLACED BY RISER STRUCTURE
Displacement by Concrete =68.371 cf
Displacement by Open Air =104.000 cf
Displacement by Trash Rack =38.000 cf
Total Water Displaced =210.371 cf
Weight of Water Displaced =13,127 lbs
RISER ANTI-FLOTATION CALCULATION
AMOUNT OF CONCRETE TO ADD TO RISER STRUCTURE
Safety Factor =1.15 Recommend 1.15 or higher
Add'l Weight for Bouyancy =5,388 lbs
Bouyant Weight of Concrete =79.60 pcf
Bouyant Weight w/ SF =69.22 pcf
Add'l Concrete to Add =77.835 cf
Less Standard Base =12.500 cf
New Base Design Required =90.335 cf
ANTI FLOTATION BLOCK DESIGN CALCULATIONS
AF Block Length =8.00 ft
AF Block Width =8.00 ft
AF Block Thickness =18.00 in
AF Block Provided =96.000 cf
Total Concrete Present =151.871 cf
Total Concrete Present =21,566 lbs
Project Name:Southstone Date:1/18/2018
Project Number:TAC-17000 Calculated By:J. Aldridge, PE
Facility ID:SWMF C
DESIGN OF RIPRAP OUTLET PROTECTION
Calculations based on NY DOT method - Pages 8.06.05 through 8.06.06 in NC Erosion Control Manual.
Flow, Q10-yr =2.48 cfs
Slope =2.08 %
Pipe Diameter, Do =24 in
=2.00 feet
Number of pipes =1
Pipe separation =0.00 feet
Manning's n =0.013
Zone from graph above =2
Outlet pipe diameter =24 in Length =12.00 ft
Outlet flowrate =2.48 cfs Width =6.00 ft
Outlet velocity =6.14 ft/sec Stone diameter =6.00 in
Material =Class B Thickness =22.00 in
Zone Material Diameter Thickness Length Width
1 Class A 3 9 4 x Do 3 x Do
2 Class B 6 22 6 x Do 3 x Do
3 Class I 13 22 8 x Do 3 x Do
4 Class I 13 22 8 x Do 3 x Do
5 Class II 23 27 10 x Do 3 x Do
6 Class II 23 27 10 x Do 3 x Do
7 Study Required
RIPRAP OUTLET PROTECTION
6.14 ft/sec
0
5
10
15
20
25
0 1 2 3 4 5 6 7 8 9 10Velocity(ft/sec)Pipe diameter (ft)
Figure 8.06.b.1
Zone 1
Zone 2
Zone 3
Zone 4
Zone 5
Zone 6 Zone 7
Storm Event: 1 year 24 hrLabel: SWMF C
Return Event: 1 yearsSubsection: Elevation-Area Volume Curve
Volume (Total)
(ft³)
Volume
(ft³)
A1+A2+sqr
(A1*A2)
(acres)
Area
(acres)
Planimeter
(ft²)
Elevation
(ft)
0.0000.0000.000.260.0620.00
3,427.0003,427.0000.940.380.0620.25
16,274.00012,847.0001.180.410.0621.00
20,775.0004,502.0001.240.420.0621.25
34,949.00014,173.0001.300.450.0622.00
55,441.00020,492.0001.410.490.0623.00
77,807.00022,366.0001.540.540.0624.00
102,104.00024,297.0001.670.580.0625.00
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 1 year 24 hrLabel: SWMF C
Return Event: 1 yearsSubsection: Outlet Input Data
Requested Pond Water Surface Elevations
ft620.00Minimum (Headwater)
ft0.10Increment (Headwater)
ft625.00Maximum (Headwater)
Outlet Connectivity
E2
(ft)
E1
(ft)
OutfallDirectionOutlet IDStructure Type
625.00623.00CulvertForwardRiserInlet Box
625.00620.40CulvertForwardOrificeOrifice-Circular
625.00617.00TWForwardCulvertCulvert-Circular
625.00619.00TWForwardSiphonOrifice-Circular
(N/A)(N/A)TailwaterTailwater Settings
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 1 year 24 hrLabel: SWMF C
Return Event: 1 yearsSubsection: Outlet Input Data
Structure ID: Culvert
Structure Type: Culvert-Circular
1Number of Barrels
in24.00Diameter
ft72.00Length
ft72.02Length (Computed Barrel)
ft/ft0.021Slope (Computed)
Outlet Control Data
0.013Manning's n
1Ke
0Kb
0Kr
ft0.00Convergence Tolerance
Inlet Control Data
Form 1Equation Form
0.0098K
2.0000M
0.0398C
0.6700Y
1T1 ratio (HW/D)
1T2 ratio (HW/D)
-1Slope Correction Factor
Use unsubmerged inlet control 0 equation below T1 elevation.
Use submerged inlet control 0 equation above T2 elevation
In transition zone between unsubmerged and submerged inlet
control,
interpolate between flows at T1 & T2...
ft618.80T1 Elevation ft³/s15.55T1 Flow
ft619.09T2 Elevation ft³/s17.77T2 Flow
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 1 year 24 hrLabel: SWMF C
Return Event: 1 yearsSubsection: Outlet Input Data
Structure ID: Riser
Structure Type: Inlet Box
1Number of Openings
ft623.00Elevation
ft²16.0Orifice Area
1Orifice Coefficient
ft16.00Weir Length
(ft^0.5)/s3.00Weir Coefficient
1K Reverse
0Manning's n
0Kev, Charged Riser
FalseWeir Submergence
FalseOrifice H to crest
Structure ID: Siphon
Structure Type: Orifice-Circular
1Number of Openings
ft620.00Elevation
in2.25Orifice Diameter
1Orifice Coefficient
Structure ID: Orifice
Structure Type: Orifice-Circular
2Number of Openings
ft621.30Elevation
in6.00Orifice Diameter
1Orifice Coefficient
Structure ID: TW
Structure Type: TW Setup, DS Channel
Free OutfallTailwater Type
Convergence Tolerances
30Maximum Iterations
ft0.01Tailwater Tolerance
(Minimum)
ft0.50Tailwater Tolerance
(Maximum)
ft0.01Headwater Tolerance
(Minimum)
ft0.50Headwater Tolerance
(Maximum)
ft³/s0.001Flow Tolerance (Minimum)
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 1 year 24 hrLabel: SWMF C
Return Event: 1 yearsSubsection: Outlet Input Data
Convergence Tolerances
ft³/s10.000Flow Tolerance (Maximum)
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 1 year 24 hrLabel: SWMF C
Return Event: 1 yearsSubsection: Composite Rating Curve
Composite Outflow Summary
Contributing StructuresConvergence Error
(ft)
Tailwater Elevation
(ft)
Flow
(ft³/s)
Water Surface
Elevation
(ft)
(no Q:
Orifice,Riser,Siphon,Culver
t)
0.00(N/A)0.00620.00
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.01620.10
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.04620.20
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.06620.30
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.07620.40
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.09620.50
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.09620.60
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.10620.70
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.11620.80
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.12620.90
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.13621.00
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.13621.10
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.14621.20
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.15621.30
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)0.20621.40
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)0.33621.50
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)0.54621.60
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)0.79621.70
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)1.12621.80
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)1.30621.90
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)1.45622.00
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)1.59622.10
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 1 year 24 hrLabel: SWMF C
Return Event: 1 yearsSubsection: Composite Rating Curve
Composite Outflow Summary
Contributing StructuresConvergence Error
(ft)
Tailwater Elevation
(ft)
Flow
(ft³/s)
Water Surface
Elevation
(ft)
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)1.72622.20
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)1.83622.30
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)1.94622.40
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)2.05622.50
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)2.15622.60
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)2.24622.70
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)2.33622.80
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)2.42622.90
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)2.50623.00
Orifice,Riser,Siphon,Culver
t
0.00(N/A)4.10623.10
Orifice,Riser,Siphon,Culver
t
0.00(N/A)6.96623.20
Orifice,Riser,Siphon,Culver
t
0.00(N/A)10.62623.30
Orifice,Riser,Siphon,Culver
t
0.00(N/A)14.95623.40
Orifice,Riser,Siphon,Culver
t
0.00(N/A)19.86623.50
Orifice,Riser,Siphon,Culver
t
0.00(N/A)25.24623.60
Orifice,Riser,Siphon,Culver
t
0.00(N/A)30.96623.70
Orifice,Riser,Siphon,Culver
t
0.00(N/A)36.10623.80
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)38.83623.90
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)39.15624.00
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 1 year 24 hrLabel: SWMF C
Return Event: 1 yearsSubsection: Composite Rating Curve
Composite Outflow Summary
Contributing StructuresConvergence Error
(ft)
Tailwater Elevation
(ft)
Flow
(ft³/s)
Water Surface
Elevation
(ft)
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)39.46624.10
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)39.78624.20
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)40.09624.30
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)40.40624.40
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)40.70624.50
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)41.01624.60
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)41.31624.70
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)41.60624.80
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)41.90624.90
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)42.20625.00
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 1 year 24 hrLabel: SWMF C (IN)
Return Event: 1 yearsSubsection: Level Pool Pond Routing Summary
Infiltration
No InfiltrationInfiltration Method
(Computed)
Initial Conditions
ft620.00Elevation (Water Surface,
Initial)
ft³0.000Volume (Initial)
ft³/s0.00Flow (Initial Outlet)
ft³/s0.00Flow (Initial Infiltration)
ft³/s0.00Flow (Initial, Total)
min1.00Time Increment
Inflow/Outflow Hydrograph Summary
ft³/s18.08Flow (Peak In)min716.00Time to Peak (Flow, In)
ft³/s0.55Flow (Peak Outlet)min908.00Time to Peak (Flow, Outlet)
ft621.60Elevation (Water Surface,
Peak)
ft³27,314.107Volume (Peak)
Mass Balance (ft³)
ft³0.000Volume (Initial)
ft³41,819.000Volume (Total Inflow)
ft³0.000Volume (Total Infiltration)
ft³17,276.000Volume (Total Outlet
Outflow)
ft³24,525.000Volume (Retained)
ft³-18.000Volume (Unrouted)
%0.0Error (Mass Balance)
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 2 yearLabel: SWMF C (IN)
Return Event: 2 yearsSubsection: Level Pool Pond Routing Summary
Infiltration
No InfiltrationInfiltration Method
(Computed)
Initial Conditions
ft620.00Elevation (Water Surface,
Initial)
ft³0.000Volume (Initial)
ft³/s0.00Flow (Initial Outlet)
ft³/s0.00Flow (Initial Infiltration)
ft³/s0.00Flow (Initial, Total)
min1.00Time Increment
Inflow/Outflow Hydrograph Summary
ft³/s23.21Flow (Peak In)min186.00Time to Peak (Flow, In)
ft³/s0.70Flow (Peak Outlet)min331.00Time to Peak (Flow, Outlet)
ft621.66Elevation (Water Surface,
Peak)
ft³28,489.972Volume (Peak)
Mass Balance (ft³)
ft³0.000Volume (Initial)
ft³33,937.000Volume (Total Inflow)
ft³0.000Volume (Total Infiltration)
ft³17,704.000Volume (Total Outlet
Outflow)
ft³16,225.000Volume (Retained)
ft³-8.000Volume (Unrouted)
%0.0Error (Mass Balance)
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 10 yearLabel: SWMF C (IN)
Return Event: 10 yearsSubsection: Level Pool Pond Routing Summary
Infiltration
No InfiltrationInfiltration Method
(Computed)
Initial Conditions
ft620.00Elevation (Water Surface,
Initial)
ft³0.000Volume (Initial)
ft³/s0.00Flow (Initial Outlet)
ft³/s0.00Flow (Initial Infiltration)
ft³/s0.00Flow (Initial, Total)
min1.00Time Increment
Inflow/Outflow Hydrograph Summary
ft³/s44.39Flow (Peak In)min186.00Time to Peak (Flow, In)
ft³/s2.48Flow (Peak Outlet)min260.00Time to Peak (Flow, Outlet)
ft622.97Elevation (Water Surface,
Peak)
ft³54,902.878Volume (Peak)
Mass Balance (ft³)
ft³0.000Volume (Initial)
ft³74,538.000Volume (Total Inflow)
ft³0.000Volume (Total Infiltration)
ft³56,517.000Volume (Total Outlet
Outflow)
ft³18,013.000Volume (Retained)
ft³-8.000Volume (Unrouted)
%0.0Error (Mass Balance)
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 25 yearLabel: SWMF C (IN)
Return Event: 25 yearsSubsection: Level Pool Pond Routing Summary
Infiltration
No InfiltrationInfiltration Method
(Computed)
Initial Conditions
ft620.00Elevation (Water Surface,
Initial)
ft³0.000Volume (Initial)
ft³/s0.00Flow (Initial Outlet)
ft³/s0.00Flow (Initial Infiltration)
ft³/s0.00Flow (Initial, Total)
min1.00Time Increment
Inflow/Outflow Hydrograph Summary
ft³/s54.76Flow (Peak In)min186.00Time to Peak (Flow, In)
ft³/s8.76Flow (Peak Outlet)min213.00Time to Peak (Flow, Outlet)
ft623.25Elevation (Water Surface,
Peak)
ft³60,839.178Volume (Peak)
Mass Balance (ft³)
ft³0.000Volume (Initial)
ft³94,322.000Volume (Total Inflow)
ft³0.000Volume (Total Infiltration)
ft³76,143.000Volume (Total Outlet
Outflow)
ft³18,171.000Volume (Retained)
ft³-8.000Volume (Unrouted)
%0.0Error (Mass Balance)
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 100 yearLabel: SWMF C (IN)
Return Event: 100 yearsSubsection: Level Pool Pond Routing Summary
Infiltration
No InfiltrationInfiltration Method
(Computed)
Initial Conditions
ft620.00Elevation (Water Surface,
Initial)
ft³0.000Volume (Initial)
ft³/s0.00Flow (Initial Outlet)
ft³/s0.00Flow (Initial Infiltration)
ft³/s0.00Flow (Initial, Total)
min1.00Time Increment
Inflow/Outflow Hydrograph Summary
ft³/s71.00Flow (Peak In)min186.00Time to Peak (Flow, In)
ft³/s22.88Flow (Peak Outlet)min198.00Time to Peak (Flow, Outlet)
ft623.56Elevation (Water Surface,
Peak)
ft³67,646.571Volume (Peak)
Mass Balance (ft³)
ft³0.000Volume (Initial)
ft³124,085.000Volume (Total Inflow)
ft³0.000Volume (Total Infiltration)
ft³105,796.000Volume (Total Outlet
Outflow)
ft³18,281.000Volume (Retained)
ft³-9.000Volume (Unrouted)
%0.0Error (Mass Balance)
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
SOUTHSTONE
TAC-17000
STORMWATER MANAGEMENT FACILITY D
DESIGN CALCULATIONS
Project Name: Southstone Date:1/18/2018
Project Number: TAC-17000 Calculated By: J. Aldridge, PE
Facility ID:SWMF D
ABOVE NORMAL POOL
Average Incremental Accumulated Calculated
Contour Stage Contour Area Contour Area Contour Vol Contour Vol Stage
[ft][ft][sf][sf][cf][cf][ft]
628.00 0.00 27,944
628.50 0.50 31,039 29,492 14,746 14,746 0.51
629.00 1.00 32,227 31,633 15,817 30,562 0.99
630.00 2.00 34,646 33,437 33,437 63,999 1.97
631.00 3.00 37,122 35,884 35,884 99,883 2.97
632.00 4.00 39,654 38,388 38,388 138,271 4.01
633.00 5.00 42,242 40,948 40,948 179,219 5.09
634.00 6.00 44,887 43,565 43,565 222,783 6.23
b =1.0823
Ks =30775
STAGE-STORAGE FUNCTION - ABOVE NORMAL POOL
y = 30752x1.09
R² = 0.9996
0
50,000
100,000
150,000
200,000
250,000
0.00 2.00 4.00 6.00 8.00Storage(CF)Stage (feet)
Storage vs. Stage
Project Name: Southstone Date:1/18/2018
Project Number: TAC-17000 Calculated By: J. Aldridge, PE
Facility ID:SWMF D
MAIN POOL
Average Incremental Accumulated Calculated
Contour Stage Contour Area Contour Area Contour Vol Contour Vol Stage
[ft][ft][sf][sf][cf][cf][ft]
624.00 0.00 14,980
625.00 1.00 16,167 15,574 15,574 15,574 1.01
626.00 2.00 17,379 16,773 16,773 32,347 1.98
627.00 3.00 18,612 17,996 17,996 50,342 2.98
627.50 3.50 19,238 18,925 9,463 59,805 3.50
628.00 4.00 20,925 20,082 10,041 69,845 4.04
b =1.0797
Ks =15470
STAGE-STORAGE FUNCTION - BELOW NORMAL POOL
y = 15470x1.0797
R² = 0.9998
0
10,000
20,000
30,000
40,000
50,000
60,000
70,000
80,000
0.00 1.00 2.00 3.00 4.00 5.00Storage(CF)Stage (feet)
Storage vs. Stage
FOREBAY
Average Incremental Accumulated Calculated
Contour Stage Contour Area Contour Area Contour Vol Contour Vol Stage
[ft][ft][sf][sf][cf][cf][ft]
624.00 0.00 3,975
625.00 1.00 4,583 4,279 4,279 4,279 1.01
626.00 2.00 5,220 4,902 4,902 9,181 1.97
627.00 3.00 5,879 5,550 5,550 14,730 2.97
627.50 3.50 6,217 6,048 3,024 17,754 3.50
628.00 4.00 7,019 6,618 3,309 21,063 4.06
b =1.1452
Ks =4230
y = 4229.7x1.1452
R² = 0.9994
0
5,000
10,000
15,000
20,000
25,000
0.00 1.00 2.00 3.00 4.00 5.00Storage(CF)Stage (feet)
Storage vs. Stage
Project Name: Southstone Date:1/18/2018
Project Number: TAC-17000 Calculated By: J. Aldridge, PE
Facility ID:SWMF D
TOTAL VOLUME
Volume of Main Pool =69,845 cf
Volume of Forebays =21,063 cf
Total Volume Below NWSE =90,908 cf
=2.09 acre-ft
Total Volume Above NWSE =179,219 cf
=4.11 acre-ft
Total Volume of Facility =270,127 cf
=6.20 acre-ft
FOREBAY CALCULATION
Total Volume Below NWSE =90,908 cf
Volume of Forebays =21,063 cf
% Forebay =23%Forebay volume should be approximately 20%
AVERAGE DEPTH OF POND
Total Volume Below NWSE =90,908 cf
Surface Area at NWSE =27,944 sf
Average Depth =3.25 Average depth must be greater than 3.0
VOLUME CALCULATIONS
Project Name: Southstone Date:1/18/2018
Project Number: TAC-17000 Calculated By: J. Aldridge, PE
Facility ID:SWMF D
DRAINAGE CHARACTERISTICS
Total Drainage Area =15.31 acres
Total Impervious Area =4.17 acres Include both onsite and offsite impervious area
% Impervious =27.25%
DETERMINATION OF REQUIRED SURFACE AREA
(REF: NCDWQ BMP Handbook, 2007).
Average Depth =3.25 ft
TSS Removal =85%
SA/DA table for Piedmont/Mountain region
3
20.0%0.97
27.2%1.24
30.0%1.34
SA/DA required =1.24
Surface Area Required =8,260 ft
=0.19 acres
Surface Area Provided =27,944 ft
SURFACE AREA CALCULATION
Lower Boundary
% Impervious
Upper Boundary
Average Depth
Project Name: Southstone Date:1/18/2018
Project Number: TAC-17000 Calculated By: J. Aldridge, PE
Facility ID:SWMF D
WATER QUALITY VOLUME
(REF: Simple Method, Schueler, 1987).
WQV = P x Rv x A / 12
where,
WQV = Water Quality Volume (acre-ft)
Rv = 0.05 + 0.009 x I, where I is % Impervious Cover
A = Area (acres)
P = Rainfall (inches)
Total Drainage Area, A =15.31 acres
Total Impervious Area =4.17 acres
% Impervious, I =27.25%
Rainfall, P =1.00 inches
Rv =0.295 acres
WQV =0.377 acre-ft
=16,413 cf
1-YEAR TREATMENT VOLUME
Pre/Post Difference in 1-Year Volume
1-Year Treatment Volume =40,453 cf
=0.929 acre-ft
ASSOCIATED DEPTH OF 1-YEAR TREATMENT VOLUME IN POND
Water Quality Volume =40,453 cf Larger of two volumes above
Ks =30775
b =1.0823
NWSE =628.00 ft
Depth of WQV in Pond =1.29 ft
=15.45 inches
Elevation =629.29 ft Spillway must be set above this elevation
WATER QUALITY VOLUME CALCULATION
Project Name: Southstone Date:1/18/2018
Project Number: TAC-17000 Calculated By: J. Aldridge, PE
Facility ID:SWMF D
DRAWDOWN DESIGN
Using falling head
Orifice Diameter =3.25 inches
Number of Orifices =1
Orifice Coefficient, Cd =0.60
Ks =30775
b =1.0823
NWSE =628.00 ft
WQV =40,453
WQV Elevation in Pond =629.29 ft
Average Incremental Incremental
WSEL Storage Siphon Flow Flow Volume Time
[ft][cf][cfs][cfs][cf][sec]
629.29 40453 0.297
629.17 36611 0.282 0.290 3,842 13,260
629.06 32800 0.266 0.274 3,812 13,895
628.95 29021 0.250 0.258 3,778 14,647
628.83 25280 0.231 0.240 3,741 15,557
628.72 21581 0.212 0.222 3,699 16,692
628.61 17929 0.190 0.201 3,652 18,167
628.49 14333 0.166 0.178 3,596 20,204
628.38 10806 0.137 0.151 3,528 23,304
628.27 7364 0.100 0.118 3,441 29,042
628.15 4045 0.044 0.072 3,319 46,253
Drawdown Time =2.44 days 2-5 day drawdown required
DRAWDOWN DESIGN
Using average head
Average Head on Orifice =0.576 inches
Orifice Coefficient, Cd =0.60
Area of Orifice =0.058 sf
Flowrate, Q =0.211 cfs
Drawdown Time =2.22 days 2-5 day drawdown required
WATER QUALITY VOLUME DRAWDOWN CALCULATION
Project Name: Southstone Date:10/19/2017
Project Number: TAC-17000 Calculated By: J. Aldridge, PE
Facility ID:SWMF D
INPUT DATA
Inside Length =4.00 ft
Inside Width =4.00 ft
Wall Thickness =6.00 in
Standard Base Length =5.00 ft
Standard Base Width =5.00 ft
Standard Base Thickness =6.00 in
Inside Height of Riser =6.90 ft
Concrete Unit Weight =142.00 pcf Unit weight of manhole concrete is 142 pcf per NC Products
Outside Diameter of Barrel =30.00 in
Drain Pipe (if present) =8.00 in
TRASH RACK DISPLACEMENT
Bottom Length / Width =7.00 ft Calculation for truncated square pyramid
Top Length / Width =1.00 ft
Height =2.00 ft
Trash Rack Displacement =38.000 cf
CONCRETE PRESENT IN RISER STRUCTURE
Riser Walls =62.100 cf
Standard Base of Riser =12.500 cf
Less Opening for Barrel =2.454 cf
Less Opening for Drain Pipe =0.175 cf
Total Concrete Less Openings =71.971 cf
Weight of Concrete =10,220 lbs
AMOUNT OF WATER DISPLACED BY RISER STRUCTURE
Displacement by Concrete =71.971 cf
Displacement by Open Air =110.400 cf
Displacement by Trash Rack =38.000 cf
Total Water Displaced =220.371 cf
Weight of Water Displaced =13,751 lbs
RISER ANTI-FLOTATION CALCULATION
AMOUNT OF CONCRETE TO ADD TO RISER STRUCTURE
Safety Factor =1.15 Recommend 1.15 or higher
Add'l Weight for Bouyancy =5,594 lbs
Bouyant Weight of Concrete =79.60 pcf
Bouyant Weight w/ SF =69.22 pcf
Add'l Concrete to Add =80.817 cf
Less Standard Base =12.500 cf
New Base Design Required =93.317 cf
ANTI FLOTATION BLOCK DESIGN CALCULATIONS
AF Block Length =8.00 ft
AF Block Width =8.00 ft
AF Block Thickness =18.00 in
AF Block Provided =96.000 cf
Total Concrete Present =155.471 cf
Total Concrete Present =22,077 lbs
Project Name:Southstone Date:1/18/2018
Project Number:TAC-17000 Calculated By:J. Aldridge, PE
Facility ID:SWMF D
DESIGN OF RIPRAP OUTLET PROTECTION
Calculations based on NY DOT method - Pages 8.06.05 through 8.06.06 in NC Erosion Control Manual.
Flow, Q10-yr =10.39 cfs
Slope =5.00 %
Pipe Diameter, Do =24 in
=2.00 feet
Number of pipes =1
Pipe separation =0.00 feet
Manning's n =0.013
Zone from graph above =3
Outlet pipe diameter =24 in Length =16.00 ft
Outlet flowrate =10.39 cfs Width =6.00 ft
Outlet velocity =12.69 ft/sec Stone diameter =13.00 in
Material =Class I Thickness =22.00 in
Zone Material Diameter Thickness Length Width
1 Class A 3 9 4 x Do 3 x Do
2 Class B 6 22 6 x Do 3 x Do
3 Class I 13 22 8 x Do 3 x Do
4 Class I 13 22 8 x Do 3 x Do
5 Class II 23 27 10 x Do 3 x Do
6 Class II 23 27 10 x Do 3 x Do
7 Study Required
RIPRAP OUTLET PROTECTION
12.69ft/sec
0
5
10
15
20
25
0 1 2 3 4 5 6 7 8 9 10Velocity(ft/sec)Pipe diameter (ft)
Figure 8.06.b.1
Zone 1
Zone 2
Zone 3
Zone 4
Zone 5
Zone 6 Zone 7
Storm Event: 1 year 24 hrLabel: SWMF D
Return Event: 1 yearsSubsection: Elevation-Area Volume Curve
Volume (Total)
(ft³)
Volume
(ft³)
A1+A2+sqr
(A1*A2)
(acres)
Area
(acres)
Planimeter
(ft²)
Elevation
(ft)
0.0000.0000.000.640.0628.00
14,739.00014,739.0002.030.710.0628.50
30,555.00015,816.0002.180.740.0629.00
63,984.00033,429.0002.300.800.0630.00
99,861.00035,877.0002.470.850.0631.00
138,242.00038,381.0002.640.910.0632.00
179,183.00040,941.0002.820.970.0633.00
222,741.00043,558.0003.001.030.0634.00
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 1 year 24 hrLabel: SWMF D
Return Event: 1 yearsSubsection: Outlet Input Data
Requested Pond Water Surface Elevations
ft628.00Minimum (Headwater)
ft0.10Increment (Headwater)
ft634.00Maximum (Headwater)
Outlet Connectivity
E2
(ft)
E1
(ft)
OutfallDirectionOutlet IDStructure Type
634.00629.40CulvertForwardOrificeOrifice-Area
634.00630.40CulvertForwardRiserInlet Box
634.00628.00CulvertForwardSiphonOrifice-Circular
634.00623.50TWForwardCulvertCulvert-Circular
(N/A)(N/A)TailwaterTailwater Settings
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 1 year 24 hrLabel: SWMF D
Return Event: 1 yearsSubsection: Outlet Input Data
Structure ID: Culvert
Structure Type: Culvert-Circular
1Number of Barrels
in24.00Diameter
ft70.00Length
ft70.09Length (Computed Barrel)
ft/ft0.050Slope (Computed)
Outlet Control Data
0.013Manning's n
1Ke
0Kb
0Kr
ft0.00Convergence Tolerance
Inlet Control Data
Form 1Equation Form
0.0098K
2.0000M
0.0398C
0.6700Y
1T1 ratio (HW/D)
1T2 ratio (HW/D)
-1Slope Correction Factor
Use unsubmerged inlet control 0 equation below T1 elevation.
Use submerged inlet control 0 equation above T2 elevation
In transition zone between unsubmerged and submerged inlet
control,
interpolate between flows at T1 & T2...
ft625.77T1 Elevation ft³/s15.55T1 Flow
ft626.06T2 Elevation ft³/s17.77T2 Flow
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 1 year 24 hrLabel: SWMF D
Return Event: 1 yearsSubsection: Outlet Input Data
Structure ID: Riser
Structure Type: Inlet Box
1Number of Openings
ft630.40Elevation
ft²16.0Orifice Area
1Orifice Coefficient
ft16.00Weir Length
(ft^0.5)/s3.00Weir Coefficient
1K Reverse
0Manning's n
0Kev, Charged Riser
FalseWeir Submergence
FalseOrifice H to crest
Structure ID: Siphon
Structure Type: Orifice-Circular
1Number of Openings
ft628.00Elevation
in3.25Orifice Diameter
1Orifice Coefficient
Structure ID: Orifice
Structure Type: Orifice-Area
3Number of Openings
ft629.40Elevation
ft²1.0Orifice Area
ft629.90Top Elevation
ft629.65Datum Elevation
1Orifice Coefficient
Structure ID: TW
Structure Type: TW Setup, DS Channel
Free OutfallTailwater Type
Convergence Tolerances
30Maximum Iterations
ft0.01Tailwater Tolerance
(Minimum)
ft0.50Tailwater Tolerance
(Maximum)
ft0.01Headwater Tolerance
(Minimum)
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 1 year 24 hrLabel: SWMF D
Return Event: 1 yearsSubsection: Outlet Input Data
Convergence Tolerances
ft0.50Headwater Tolerance
(Maximum)
ft³/s0.001Flow Tolerance (Minimum)
ft³/s10.000Flow Tolerance (Maximum)
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 1 year 24 hrLabel: SWMF D
Return Event: 1 yearsSubsection: Composite Rating Curve
Composite Outflow Summary
Contributing StructuresConvergence Error
(ft)
Tailwater Elevation
(ft)
Flow
(ft³/s)
Water Surface
Elevation
(ft)
(no Q:
Orifice,Riser,Siphon,Culver
t)
0.00(N/A)0.00628.00
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.02628.10
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.06628.20
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.11628.30
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.14628.40
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.17628.50
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.19628.60
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.21628.70
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.22628.80
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.24628.90
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.26629.00
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.27629.10
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.29629.20
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.30629.30
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.31629.40
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)1.77629.50
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)3.22629.60
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)4.68629.70
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)6.13629.80
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)7.59629.90
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)8.92630.00
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)10.07630.10
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 1 year 24 hrLabel: SWMF D
Return Event: 1 yearsSubsection: Composite Rating Curve
Composite Outflow Summary
Contributing StructuresConvergence Error
(ft)
Tailwater Elevation
(ft)
Flow
(ft³/s)
Water Surface
Elevation
(ft)
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)11.10630.20
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)12.06630.30
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)12.92630.40
Orifice,Riser,Siphon,Culver
t
0.00(N/A)15.25630.50
Orifice,Riser,Siphon,Culver
t
0.00(N/A)18.80630.60
Orifice,Riser,Siphon,Culver
t
0.00(N/A)23.13630.70
Orifice,Riser,Siphon,Culver
t
0.00(N/A)28.07630.80
Orifice,Riser,Siphon,Culver
t
0.00(N/A)33.45630.90
Orifice,Riser,Siphon,Culver
t
0.00(N/A)36.29631.00
Orifice,Riser,Siphon,Culver
t
0.00(N/A)38.09631.10
Orifice,Riser,Siphon,Culver
t
0.00(N/A)39.49631.20
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)40.18631.30
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)40.48631.40
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)40.79631.50
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)41.09631.60
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)41.40631.70
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)41.69631.80
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)41.99631.90
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)42.28632.00
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 1 year 24 hrLabel: SWMF D
Return Event: 1 yearsSubsection: Composite Rating Curve
Composite Outflow Summary
Contributing StructuresConvergence Error
(ft)
Tailwater Elevation
(ft)
Flow
(ft³/s)
Water Surface
Elevation
(ft)
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)42.58632.10
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)42.87632.20
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)43.15632.30
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)43.44632.40
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)43.73632.50
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)44.01632.60
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)44.29632.70
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)44.57632.80
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)44.85632.90
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)45.12633.00
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)45.39633.10
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)45.67633.20
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)45.94633.30
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)46.21633.40
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)46.47633.50
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)46.74633.60
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)47.00633.70
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)47.27633.80
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)47.53633.90
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)47.79634.00
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 1 year 24 hrLabel: SWMF D (IN)
Return Event: 1 yearsSubsection: Level Pool Pond Routing Summary
Infiltration
No InfiltrationInfiltration Method
(Computed)
Initial Conditions
ft628.00Elevation (Water Surface,
Initial)
ft³0.000Volume (Initial)
ft³/s0.00Flow (Initial Outlet)
ft³/s0.00Flow (Initial Infiltration)
ft³/s0.00Flow (Initial, Total)
min1.00Time Increment
Inflow/Outflow Hydrograph Summary
ft³/s26.72Flow (Peak In)min716.00Time to Peak (Flow, In)
ft³/s0.63Flow (Peak Outlet)min1,000.00Time to Peak (Flow, Outlet)
ft629.42Elevation (Water Surface,
Peak)
ft³44,353.137Volume (Peak)
Mass Balance (ft³)
ft³0.000Volume (Initial)
ft³61,999.000Volume (Total Inflow)
ft³0.000Volume (Total Infiltration)
ft³18,294.000Volume (Total Outlet
Outflow)
ft³43,685.000Volume (Retained)
ft³-20.000Volume (Unrouted)
%0.0Error (Mass Balance)
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 2 yearLabel: SWMF D (IN)
Return Event: 2 yearsSubsection: Level Pool Pond Routing Summary
Infiltration
No InfiltrationInfiltration Method
(Computed)
Initial Conditions
ft628.00Elevation (Water Surface,
Initial)
ft³0.000Volume (Initial)
ft³/s0.00Flow (Initial Outlet)
ft³/s0.00Flow (Initial Infiltration)
ft³/s0.00Flow (Initial, Total)
min1.00Time Increment
Inflow/Outflow Hydrograph Summary
ft³/s33.77Flow (Peak In)min186.00Time to Peak (Flow, In)
ft³/s0.91Flow (Peak Outlet)min361.00Time to Peak (Flow, Outlet)
ft629.44Elevation (Water Surface,
Peak)
ft³45,004.278Volume (Peak)
Mass Balance (ft³)
ft³0.000Volume (Initial)
ft³49,694.000Volume (Total Inflow)
ft³0.000Volume (Total Infiltration)
ft³23,138.000Volume (Total Outlet
Outflow)
ft³26,540.000Volume (Retained)
ft³-16.000Volume (Unrouted)
%0.0Error (Mass Balance)
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 10 yearLabel: SWMF D (IN)
Return Event: 10 yearsSubsection: Level Pool Pond Routing Summary
Infiltration
No InfiltrationInfiltration Method
(Computed)
Initial Conditions
ft628.00Elevation (Water Surface,
Initial)
ft³0.000Volume (Initial)
ft³/s0.00Flow (Initial Outlet)
ft³/s0.00Flow (Initial Infiltration)
ft³/s0.00Flow (Initial, Total)
min1.00Time Increment
Inflow/Outflow Hydrograph Summary
ft³/s68.18Flow (Peak In)min186.00Time to Peak (Flow, In)
ft³/s10.39Flow (Peak Outlet)min214.00Time to Peak (Flow, Outlet)
ft630.13Elevation (Water Surface,
Peak)
ft³68,524.344Volume (Peak)
Mass Balance (ft³)
ft³0.000Volume (Initial)
ft³113,843.000Volume (Total Inflow)
ft³0.000Volume (Total Infiltration)
ft³86,746.000Volume (Total Outlet
Outflow)
ft³27,081.000Volume (Retained)
ft³-15.000Volume (Unrouted)
%0.0Error (Mass Balance)
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 25 yearLabel: SWMF D (IN)
Return Event: 25 yearsSubsection: Level Pool Pond Routing Summary
Infiltration
No InfiltrationInfiltration Method
(Computed)
Initial Conditions
ft628.00Elevation (Water Surface,
Initial)
ft³0.000Volume (Initial)
ft³/s0.00Flow (Initial Outlet)
ft³/s0.00Flow (Initial Infiltration)
ft³/s0.00Flow (Initial, Total)
min1.00Time Increment
Inflow/Outflow Hydrograph Summary
ft³/s85.16Flow (Peak In)min186.00Time to Peak (Flow, In)
ft³/s16.59Flow (Peak Outlet)min208.00Time to Peak (Flow, Outlet)
ft630.54Elevation (Water Surface,
Peak)
ft³82,967.586Volume (Peak)
Mass Balance (ft³)
ft³0.000Volume (Initial)
ft³145,561.000Volume (Total Inflow)
ft³0.000Volume (Total Infiltration)
ft³118,310.000Volume (Total Outlet
Outflow)
ft³27,236.000Volume (Retained)
ft³-15.000Volume (Unrouted)
%0.0Error (Mass Balance)
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 100 yearLabel: SWMF D (IN)
Return Event: 100 yearsSubsection: Level Pool Pond Routing Summary
Infiltration
No InfiltrationInfiltration Method
(Computed)
Initial Conditions
ft628.00Elevation (Water Surface,
Initial)
ft³0.000Volume (Initial)
ft³/s0.00Flow (Initial Outlet)
ft³/s0.00Flow (Initial Infiltration)
ft³/s0.00Flow (Initial, Total)
min1.00Time Increment
Inflow/Outflow Hydrograph Summary
ft³/s111.82Flow (Peak In)min186.00Time to Peak (Flow, In)
ft³/s35.32Flow (Peak Outlet)min198.00Time to Peak (Flow, Outlet)
ft630.97Elevation (Water Surface,
Peak)
ft³98,596.504Volume (Peak)
Mass Balance (ft³)
ft³0.000Volume (Initial)
ft³193,584.000Volume (Total Inflow)
ft³0.000Volume (Total Infiltration)
ft³166,191.000Volume (Total Outlet
Outflow)
ft³27,378.000Volume (Retained)
ft³-15.000Volume (Unrouted)
%0.0Error (Mass Balance)
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
SOUTHSTONE
TAC-17000
STORMWATER MANAGEMENT FACILITY E
DESIGN CALCULATIONS
Project Name: Southstone Date:1/18/2018
Project Number: TAC-17000 Calculated By: J. Aldridge, PE
Facility ID:SWMF E
ABOVE NORMAL POOL
Average Incremental Accumulated Calculated
Contour Stage Contour Area Contour Area Contour Vol Contour Vol Stage
[ft][ft][sf][sf][cf][cf][ft]
614.00 0.00 13,212
614.25 0.25 17,952 15,582 3,896 3,896 0.25
615.00 1.00 19,897 18,925 14,193 18,089 0.99
615.25 1.25 20,555 20,226 5,057 23,145 1.23
616.00 2.00 22,653 21,604 16,203 39,348 1.97
617.00 3.00 24,034 23,344 23,344 62,692 2.98
618.00 4.00 25,448 24,741 24,741 87,433 4.00
619.00 5.00 26,891 26,170 26,170 113,602 5.04
620.00 6.00 28,365 27,628 27,628 141,230 6.11
b =1.1296
Ks =18273
STAGE-STORAGE FUNCTION - ABOVE NORMAL POOL
y = 18273x1.1296
R² = 0.9998
0
20,000
40,000
60,000
80,000
100,000
120,000
140,000
160,000
0.00 2.00 4.00 6.00 8.00Storage(CF)Stage (feet)
Storage vs. Stage
Project Name: Southstone Date:1/18/2018
Project Number: TAC-17000 Calculated By: J. Aldridge, PE
Facility ID:SWMF E
ABOVE NORMAL POOL
Normal Water Surface Elevation =
Temporary Ponding Elevation =
Wetland Surface Area =
% of Wetland
Zone Surface Area
Deep Pool - Forebay 613.50 to 611.00 15%
Deep Pool - Non Forebay 613.50 to 611.00 9%
Shallow Water 614.00 to 613.50 40%
Temporary Inundation 615.25 to 614.00 36%
`
WETLAND ZONE CALCULATIONS
614.00
20,555
Elevation Measured Area
3,079
1,846
8,287
7,341
615.25
[ft][sf]
Project Name: Southstone Date:1/18/2018
Project Number: TAC-17000 Calculated By: J. Aldridge, PE
Facility ID:SWMF E
1-INCH TREATMENT VOLUME
(REF: Simple Method, Schueler, 1987).
WQV = P x Rv x A / 12
where,
WQV = Water Quality Volume (acre-ft)
Rv = 0.05 + 0.009 x I, where I is % Impervious Cover
A = Area (acres)
P = Rainfall (inches)
Total Drainage Area, A =17.24 acres
Total Impervious Area =6.18 acres
% Impervious, I =35.87%
Rainfall, P =1.00 inches
Rv =0.373 acres
WQV =0.536 acre-ft
=23,329 cf
1-YEAR TREATMENT VOLUME
Pre/Post Difference in 1-Year Volume
1-Year Treatment Volume =20,227 cf
=0.464 acre-ft
ASSOCIATED DEPTH OF 1-YEAR TREATMENT VOLUME IN POND
Water Quality Volume =23,329 cf Larger of two volumes above
Ks =18273
b =1.1296
NWSE =614.00 ft
Depth of WQV in Pond =1.24 ft
=14.90 inches
Elevation =615.24 ft Spillway must be set above this elevation
WATER QUALITY VOLUME CALCULATION
Project Name: Southstone Date:1/18/2018
Project Number: TAC-17000 Calculated By: J. Aldridge, PE
Facility ID:SWMF E
DRAWDOWN DESIGN
Using falling head
Orifice Diameter =2.50 inches
Number of Orifices =1
Orifice Coefficient, Cd =0.60
Ks =18273
b =1.1296
NWSE =614.00 ft
WQV =23,329
WQV Elevation in Pond =615.24 ft
Average Incremental Incremental
WSEL Storage Siphon Flow Flow Volume Time
[ft][cf][cfs][cfs][cf][sec]
615.24 23329 0.175
615.13 21050 0.166 0.171 2,279 13,365
615.03 18799 0.157 0.162 2,251 13,913
614.92 16579 0.148 0.153 2,220 14,555
614.81 14393 0.138 0.143 2,187 15,322
614.70 12244 0.127 0.132 2,149 16,262
614.59 10137 0.115 0.121 2,106 17,459
614.49 8080 0.101 0.108 2,057 19,060
614.38 6082 0.086 0.093 1,998 21,382
614.27 4158 0.067 0.076 1,925 25,264
614.16 2333 0.036 0.051 1,825 35,453
Drawdown Time =2.22 days 2-5 day drawdown required
DRAWDOWN DESIGN
Using average head
Average Head on Orifice =0.569 inches
Orifice Coefficient, Cd =0.60
Area of Orifice =0.034 sf
Flowrate, Q =0.124 cfs
Drawdown Time =2.18 days 2-5 day drawdown required
WATER QUALITY VOLUME DRAWDOWN CALCULATION
Project Name: Southstone Date:1/18/2018
Project Number: TAC-17000 Calculated By: J. Aldridge, PE
Facility ID:SWMF E
INPUT DATA
Inside Length =4.00 ft
Inside Width =4.00 ft
Wall Thickness =6.00 in
Standard Base Length =5.00 ft
Standard Base Width =5.00 ft
Standard Base Thickness =6.00 in
Inside Height of Riser =4.00 ft
Concrete Unit Weight =142.00 pcf Unit weight of manhole concrete is 142 pcf per NC Products
Outside Diameter of Barrel =30.00 in
Drain Pipe (if present) =8.00 in
TRASH RACK DISPLACEMENT
Bottom Length / Width =7.00 ft Calculation for truncated square pyramid
Top Length / Width =1.00 ft
Height =2.00 ft
Trash Rack Displacement =38.000 cf
CONCRETE PRESENT IN RISER STRUCTURE
Riser Walls =36.000 cf
Standard Base of Riser =12.500 cf
Less Opening for Barrel =2.454 cf
Less Opening for Drain Pipe =0.175 cf
Total Concrete Less Openings =45.871 cf
Weight of Concrete =6,514 lbs
AMOUNT OF WATER DISPLACED BY RISER STRUCTURE
Displacement by Concrete =45.871 cf
Displacement by Open Air =64.000 cf
Displacement by Trash Rack =38.000 cf
Total Water Displaced =147.871 cf
Weight of Water Displaced =9,227 lbs
RISER ANTI-FLOTATION CALCULATION
AMOUNT OF CONCRETE TO ADD TO RISER STRUCTURE
Safety Factor =1.15 Recommend 1.15 or higher
Add'l Weight for Bouyancy =4,098 lbs
Bouyant Weight of Concrete =79.60 pcf
Bouyant Weight w/ SF =69.22 pcf
Add'l Concrete to Add =59.198 cf
Less Standard Base =12.500 cf
New Base Design Required =71.698 cf
ANTI FLOTATION BLOCK DESIGN CALCULATIONS
AF Block Length =8.00 ft
AF Block Width =8.00 ft
AF Block Thickness =15.00 in
AF Block Provided =80.000 cf
Total Concrete Present =113.371 cf
Total Concrete Present =16,099 lbs
Project Name:Southstone Date:1/18/2018
Project Number:TAC-17000 Calculated By:J. Aldridge, PE
Facility ID:SWMF E
DESIGN OF RIPRAP OUTLET PROTECTION
Calculations based on NY DOT method - Pages 8.06.05 through 8.06.06 in NC Erosion Control Manual.
Flow, Q10-yr =9.18 cfs
Slope =1.35 %
Pipe Diameter, Do =24 in
=2.00 feet
Number of pipes =1
Pipe separation =0.00 feet
Manning's n =0.013
Zone from graph above =2
Outlet pipe diameter =24 in Length =12.00 ft
Outlet flowrate =9.18 cfs Width =6.00 ft
Outlet velocity =7.63 ft/sec Stone diameter =6.00 in
Material =Class B Thickness =22.00 in
Zone Material Diameter Thickness Length Width
1 Class A 3 9 4 x Do 3 x Do
2 Class B 6 22 6 x Do 3 x Do
3 Class I 13 22 8 x Do 3 x Do
4 Class I 13 22 8 x Do 3 x Do
5 Class II 23 27 10 x Do 3 x Do
6 Class II 23 27 10 x Do 3 x Do
7 Study Required
RIPRAP OUTLET PROTECTION
7.63 ft/sec
0
5
10
15
20
25
0 1 2 3 4 5 6 7 8 9 10Velocity(ft/sec)Pipe diameter (ft)
Figure 8.06.b.1
Zone 1
Zone 2
Zone 3
Zone 4
Zone 5
Zone 6 Zone 7
Storm Event: 1 year 24 hrLabel: SWMF E
Return Event: 1 yearsSubsection: Elevation-Area Volume Curve
Volume (Total)
(ft³)
Volume
(ft³)
A1+A2+sqr
(A1*A2)
(ft²)
Area
(ft²)
Planimeter
(ft²)
Elevation
(ft)
0.0000.0000.0013,212.000.0614.00
3,880.0003,880.00046,564.7117,952.000.0614.25
18,068.00014,187.00056,748.5019,897.000.0615.00
23,124.0005,056.00060,675.3220,555.000.0615.25
39,320.00016,197.00064,786.5222,653.000.0616.00
62,661.00023,340.00070,020.2924,034.000.0617.00
87,398.00024,738.00074,212.9025,448.000.0618.00
113,564.00026,166.00078,498.5526,891.000.0619.00
141,189.00027,625.00082,874.1728,365.000.0620.00
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 1 year 24 hrLabel: SWMF E
Return Event: 1 yearsSubsection: Outlet Input Data
Requested Pond Water Surface Elevations
ft614.00Minimum (Headwater)
ft0.10Increment (Headwater)
ft620.00Maximum (Headwater)
Outlet Connectivity
E2
(ft)
E1
(ft)
OutfallDirectionOutlet IDStructure Type
628.00632.00CulvertForwardRiserInlet Box
628.00623.30CulvertForwardOrificeOrifice-Circular
628.00622.00TWForwardCulvertCulvert-Circular
628.00628.00TWForwardSiphonOrifice-Circular
(N/A)(N/A)TailwaterTailwater Settings
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 1 year 24 hrLabel: SWMF E
Return Event: 1 yearsSubsection: Outlet Input Data
Structure ID: Culvert
Structure Type: Culvert-Circular
1Number of Barrels
in24.00Diameter
ft37.00Length
ft37.00Length (Computed Barrel)
ft/ft0.014Slope (Computed)
Outlet Control Data
0.013Manning's n
1Ke
0Kb
0Kr
ft0.00Convergence Tolerance
Inlet Control Data
Form 1Equation Form
0.0098K
2.0000M
0.0398C
0.6700Y
1T1 ratio (HW/D)
1T2 ratio (HW/D)
-1Slope Correction Factor
Use unsubmerged inlet control 0 equation below T1 elevation.
Use submerged inlet control 0 equation above T2 elevation
In transition zone between unsubmerged and submerged inlet
control,
interpolate between flows at T1 & T2...
ft615.81T1 Elevation ft³/s15.55T1 Flow
ft616.10T2 Elevation ft³/s17.77T2 Flow
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 1 year 24 hrLabel: SWMF E
Return Event: 1 yearsSubsection: Outlet Input Data
Structure ID: Riser
Structure Type: Inlet Box
1Number of Openings
ft617.50Elevation
ft²16.0Orifice Area
1Orifice Coefficient
ft16.00Weir Length
(ft^0.5)/s3.00Weir Coefficient
1K Reverse
0Manning's n
0Kev, Charged Riser
FalseWeir Submergence
FalseOrifice H to crest
Structure ID: Siphon
Structure Type: Orifice-Circular
1Number of Openings
ft614.00Elevation
in2.50Orifice Diameter
1Orifice Coefficient
Structure ID: Orifice
Structure Type: Orifice-Circular
2Number of Openings
ft615.30Elevation
in6.00Orifice Diameter
1Orifice Coefficient
Structure ID: TW
Structure Type: TW Setup, DS Channel
Free OutfallTailwater Type
Convergence Tolerances
30Maximum Iterations
ft0.01Tailwater Tolerance
(Minimum)
ft0.50Tailwater Tolerance
(Maximum)
ft0.01Headwater Tolerance
(Minimum)
ft0.50Headwater Tolerance
(Maximum)
ft³/s0.001Flow Tolerance (Minimum)
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 1 year 24 hrLabel: SWMF E
Return Event: 1 yearsSubsection: Outlet Input Data
Convergence Tolerances
ft³/s10.000Flow Tolerance (Maximum)
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 1 year 24 hrLabel: SWMF E
Return Event: 1 yearsSubsection: Composite Rating Curve
Composite Outflow Summary
Contributing StructuresConvergence Error
(ft)
Tailwater Elevation
(ft)
Flow
(ft³/s)
Water Surface
Elevation
(ft)
(no Q:
Riser,Orifice,Culvert,Sipho
n)
0.00(N/A)0.00614.00
Siphon (no Q:
Riser,Orifice,Culvert)
0.00(N/A)0.01614.10
Siphon (no Q:
Riser,Orifice,Culvert)
0.00(N/A)0.05614.20
Siphon (no Q:
Riser,Orifice,Culvert)
0.00(N/A)0.07614.30
Siphon (no Q:
Riser,Orifice,Culvert)
0.00(N/A)0.09614.40
Siphon (no Q:
Riser,Orifice,Culvert)
0.00(N/A)0.10614.50
Siphon (no Q:
Riser,Orifice,Culvert)
0.00(N/A)0.12614.60
Siphon (no Q:
Riser,Orifice,Culvert)
0.00(N/A)0.13614.70
Siphon (no Q:
Riser,Orifice,Culvert)
0.00(N/A)0.14614.80
Siphon (no Q:
Riser,Orifice,Culvert)
0.00(N/A)0.15614.90
Siphon (no Q:
Riser,Orifice,Culvert)
0.00(N/A)0.16615.00
Siphon (no Q:
Riser,Orifice,Culvert)
0.00(N/A)0.16615.10
Siphon (no Q:
Riser,Orifice,Culvert)
0.00(N/A)0.17615.20
Siphon (no Q:
Riser,Orifice,Culvert)
0.00(N/A)0.18615.30
Orifice,Culvert,Siphon
(no Q: Riser)
0.00(N/A)0.23615.40
Orifice,Culvert,Siphon
(no Q: Riser)
0.00(N/A)0.38615.50
Orifice,Culvert,Siphon
(no Q: Riser)
0.00(N/A)0.58615.60
Orifice,Culvert,Siphon
(no Q: Riser)
0.00(N/A)0.84615.70
Orifice,Culvert,Siphon
(no Q: Riser)
0.00(N/A)1.17615.80
Orifice,Culvert,Siphon
(no Q: Riser)
0.00(N/A)1.35615.90
Orifice,Culvert,Siphon
(no Q: Riser)
0.00(N/A)1.49616.00
Orifice,Culvert,Siphon
(no Q: Riser)
0.00(N/A)1.64616.10
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 1 year 24 hrLabel: SWMF E
Return Event: 1 yearsSubsection: Composite Rating Curve
Composite Outflow Summary
Contributing StructuresConvergence Error
(ft)
Tailwater Elevation
(ft)
Flow
(ft³/s)
Water Surface
Elevation
(ft)
Orifice,Culvert,Siphon
(no Q: Riser)
0.00(N/A)1.76616.20
Orifice,Culvert,Siphon
(no Q: Riser)
0.00(N/A)1.88616.30
Orifice,Culvert,Siphon
(no Q: Riser)
0.00(N/A)1.99616.40
Orifice,Culvert,Siphon
(no Q: Riser)
0.00(N/A)2.10616.50
Orifice,Culvert,Siphon
(no Q: Riser)
0.00(N/A)2.20616.60
Orifice,Culvert,Siphon
(no Q: Riser)
0.00(N/A)2.29616.70
Orifice,Culvert,Siphon
(no Q: Riser)
0.00(N/A)2.38616.80
Orifice,Culvert,Siphon
(no Q: Riser)
0.00(N/A)2.47616.90
Orifice,Culvert,Siphon
(no Q: Riser)
0.00(N/A)2.57617.00
Orifice,Culvert,Siphon
(no Q: Riser)
0.00(N/A)2.64617.10
Orifice,Culvert,Siphon
(no Q: Riser)
0.00(N/A)2.72617.20
Orifice,Culvert,Siphon
(no Q: Riser)
0.00(N/A)2.79617.30
Orifice,Culvert,Siphon
(no Q: Riser)
0.00(N/A)2.87617.40
Orifice,Culvert,Siphon
(no Q: Riser)
0.00(N/A)2.95617.50
Riser,Orifice,Culvert,Sipho
n
0.00(N/A)4.53617.60
Riser,Orifice,Culvert,Sipho
n
0.00(N/A)7.37617.70
Riser,Orifice,Culvert,Sipho
n
0.00(N/A)11.04617.80
Riser,Orifice,Culvert,Sipho
n
0.00(N/A)15.17617.90
Riser,Orifice,Culvert,Sipho
n
0.00(N/A)19.72618.00
Riser,Orifice,Culvert,Sipho
n
0.00(N/A)24.49618.10
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 1 year 24 hrLabel: SWMF E
Return Event: 1 yearsSubsection: Composite Rating Curve
Composite Outflow Summary
Contributing StructuresConvergence Error
(ft)
Tailwater Elevation
(ft)
Flow
(ft³/s)
Water Surface
Elevation
(ft)
Riser,Orifice,Culvert,Sipho
n
0.00(N/A)28.95618.20
Riser,Culvert,Siphon (no
Q: Orifice)
0.00(N/A)29.69618.30
Riser,Culvert,Siphon (no
Q: Orifice)
0.00(N/A)30.11618.40
Riser,Culvert,Siphon (no
Q: Orifice)
0.00(N/A)30.53618.50
Riser,Culvert,Siphon (no
Q: Orifice)
0.00(N/A)30.94618.60
Riser,Culvert,Siphon (no
Q: Orifice)
0.00(N/A)31.35618.70
Riser,Culvert,Siphon (no
Q: Orifice)
0.00(N/A)31.74618.80
Riser,Culvert,Siphon (no
Q: Orifice)
0.00(N/A)32.14618.90
Riser,Culvert,Siphon (no
Q: Orifice)
0.00(N/A)32.53619.00
Riser,Culvert,Siphon (no
Q: Orifice)
0.00(N/A)32.92619.10
Riser,Culvert,Siphon (no
Q: Orifice)
0.00(N/A)33.30619.20
Riser,Culvert,Siphon (no
Q: Orifice)
0.00(N/A)33.68619.30
Riser,Culvert,Siphon (no
Q: Orifice)
0.00(N/A)34.05619.40
Riser,Culvert,Siphon (no
Q: Orifice)
0.00(N/A)34.43619.50
Riser,Culvert,Siphon (no
Q: Orifice)
0.00(N/A)34.79619.60
Riser,Culvert,Siphon (no
Q: Orifice)
0.00(N/A)35.15619.70
Riser,Culvert,Siphon (no
Q: Orifice)
0.00(N/A)35.51619.80
Riser,Culvert,Siphon (no
Q: Orifice)
0.00(N/A)35.87619.90
Riser,Culvert,Siphon (no
Q: Orifice)
0.00(N/A)36.21620.00
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 1 year 24 hrLabel: SWMF E (IN)
Return Event: 1 yearsSubsection: Level Pool Pond Routing Summary
Infiltration
No InfiltrationInfiltration Method
(Computed)
Initial Conditions
ft614.00Elevation (Water Surface,
Initial)
ft³0.000Volume (Initial)
ft³/s0.00Flow (Initial Outlet)
ft³/s0.00Flow (Initial Infiltration)
ft³/s0.00Flow (Initial, Total)
min1.00Time Increment
Inflow/Outflow Hydrograph Summary
ft³/s28.40Flow (Peak In)min716.00Time to Peak (Flow, In)
ft³/s1.34Flow (Peak Outlet)min823.00Time to Peak (Flow, Outlet)
ft615.89Elevation (Water Surface,
Peak)
ft³36,886.472Volume (Peak)
Mass Balance (ft³)
ft³0.000Volume (Initial)
ft³66,094.000Volume (Total Inflow)
ft³0.000Volume (Total Infiltration)
ft³36,969.000Volume (Total Outlet
Outflow)
ft³29,095.000Volume (Retained)
ft³-30.000Volume (Unrouted)
%0.0Error (Mass Balance)
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 2 yearLabel: SWMF E (IN)
Return Event: 2 yearsSubsection: Level Pool Pond Routing Summary
Infiltration
No InfiltrationInfiltration Method
(Computed)
Initial Conditions
ft614.00Elevation (Water Surface,
Initial)
ft³0.000Volume (Initial)
ft³/s0.00Flow (Initial Outlet)
ft³/s0.00Flow (Initial Infiltration)
ft³/s0.00Flow (Initial, Total)
min1.00Time Increment
Inflow/Outflow Hydrograph Summary
ft³/s35.58Flow (Peak In)min186.00Time to Peak (Flow, In)
ft³/s1.52Flow (Peak Outlet)min293.00Time to Peak (Flow, Outlet)
ft616.02Elevation (Water Surface,
Peak)
ft³39,749.560Volume (Peak)
Mass Balance (ft³)
ft³0.000Volume (Initial)
ft³52,638.000Volume (Total Inflow)
ft³0.000Volume (Total Infiltration)
ft³34,295.000Volume (Total Outlet
Outflow)
ft³18,332.000Volume (Retained)
ft³-11.000Volume (Unrouted)
%0.0Error (Mass Balance)
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 10 yearLabel: SWMF E (IN)
Return Event: 10 yearsSubsection: Level Pool Pond Routing Summary
Infiltration
No InfiltrationInfiltration Method
(Computed)
Initial Conditions
ft614.00Elevation (Water Surface,
Initial)
ft³0.000Volume (Initial)
ft³/s0.00Flow (Initial Outlet)
ft³/s0.00Flow (Initial Infiltration)
ft³/s0.00Flow (Initial, Total)
min1.00Time Increment
Inflow/Outflow Hydrograph Summary
ft³/s73.94Flow (Peak In)min186.00Time to Peak (Flow, In)
ft³/s9.18Flow (Peak Outlet)min218.00Time to Peak (Flow, Outlet)
ft617.75Elevation (Water Surface,
Peak)
ft³81,062.566Volume (Peak)
Mass Balance (ft³)
ft³0.000Volume (Initial)
ft³123,230.000Volume (Total Inflow)
ft³0.000Volume (Total Infiltration)
ft³102,352.000Volume (Total Outlet
Outflow)
ft³20,864.000Volume (Retained)
ft³-13.000Volume (Unrouted)
%0.0Error (Mass Balance)
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 25 yearLabel: SWMF E (IN)
Return Event: 25 yearsSubsection: Level Pool Pond Routing Summary
Infiltration
No InfiltrationInfiltration Method
(Computed)
Initial Conditions
ft614.00Elevation (Water Surface,
Initial)
ft³0.000Volume (Initial)
ft³/s0.00Flow (Initial Outlet)
ft³/s0.00Flow (Initial Infiltration)
ft³/s0.00Flow (Initial, Total)
min1.00Time Increment
Inflow/Outflow Hydrograph Summary
ft³/s92.94Flow (Peak In)min186.00Time to Peak (Flow, In)
ft³/s22.55Flow (Peak Outlet)min202.00Time to Peak (Flow, Outlet)
ft618.06Elevation (Water Surface,
Peak)
ft³88,907.760Volume (Peak)
Mass Balance (ft³)
ft³0.000Volume (Initial)
ft³158,400.000Volume (Total Inflow)
ft³0.000Volume (Total Infiltration)
ft³137,420.000Volume (Total Outlet
Outflow)
ft³20,967.000Volume (Retained)
ft³-13.000Volume (Unrouted)
%0.0Error (Mass Balance)
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 100 yearLabel: SWMF E (IN)
Return Event: 100 yearsSubsection: Level Pool Pond Routing Summary
Infiltration
No InfiltrationInfiltration Method
(Computed)
Initial Conditions
ft614.00Elevation (Water Surface,
Initial)
ft³0.000Volume (Initial)
ft³/s0.00Flow (Initial Outlet)
ft³/s0.00Flow (Initial Infiltration)
ft³/s0.00Flow (Initial, Total)
min1.00Time Increment
Inflow/Outflow Hydrograph Summary
ft³/s122.84Flow (Peak In)min186.00Time to Peak (Flow, In)
ft³/s31.92Flow (Peak Outlet)min201.00Time to Peak (Flow, Outlet)
ft618.84Elevation (Water Surface,
Peak)
ft³109,367.555Volume (Peak)
Mass Balance (ft³)
ft³0.000Volume (Initial)
ft³211,828.000Volume (Total Inflow)
ft³0.000Volume (Total Infiltration)
ft³190,781.000Volume (Total Outlet
Outflow)
ft³21,034.000Volume (Retained)
ft³-13.000Volume (Unrouted)
%0.0Error (Mass Balance)
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
SOUTHSTONE
TAC-17000
STORMWATER MANAGEMENT FACILITY F
DESIGN CALCULATIONS
Project Name: Southstone Date:1/18/2018
Project Number: TAC-17000 Calculated By: J. Aldridge, PE
Facility ID:SWMF F
ABOVE NORMAL POOL
Average Incremental Accumulated Calculated
Contour Stage Contour Area Contour Area Contour Vol Contour Vol Stage
[ft][ft][sf][sf][cf][cf][ft]
639.00 0.00 8,986
639.25 0.25 12,481 10,734 2,683 2,683 0.25
640.00 1.00 13,564 13,023 9,767 12,450 1.00
640.25 1.25 13,932 13,748 3,437 15,887 1.24
641.00 2.00 15,057 14,495 10,871 26,758 1.98
642.00 3.00 16,606 15,832 15,832 42,590 3.00
643.00 4.00 18,212 17,409 17,409 59,999 4.07
b =1.1172
Ks =12504
STAGE-STORAGE FUNCTION - ABOVE NORMAL POOL
y = 12504x1.1172
R² = 0.9999
0
10,000
20,000
30,000
40,000
50,000
60,000
70,000
0.00 1.00 2.00 3.00 4.00 5.00Storage(CF)Stage (feet)
Storage vs. Stage
Project Name: Southstone Date:1/18/2018
Project Number: TAC-17000 Calculated By: J. Aldridge, PE
Facility ID:SWMF F
ABOVE NORMAL POOL
Normal Water Surface Elevation =
Temporary Ponding Elevation =
Wetland Surface Area =
% of Wetland
Zone Surface Area
Deep Pool - Forebay 638.50 to 636.00 13%
Deep Pool - Non Forebay 638.50 to 636.00 13%
Shallow Water 639.00 to 638.50 39%
Temporary Inundation 640.25 to 639.00 36%
`
4,946
WETLAND ZONE CALCULATIONS
639.00
640.25
13,932
Elevation Measured Area
[ft][sf]
1,818
1,777
5,392
Project Name: Southstone Date:1/18/2018
Project Number: TAC-17000 Calculated By: J. Aldridge, PE
Facility ID:SWMF F
1-INCH TREATMENT VOLUME
(REF: Simple Method, Schueler, 1987).
WQV = P x Rv x A / 12
where,
WQV = Water Quality Volume (acre-ft)
Rv = 0.05 + 0.009 x I, where I is % Impervious Cover
A = Area (acres)
P = Rainfall (inches)
Total Drainage Area, A =13.60 acres
Total Impervious Area =2.87 acres
% Impervious, I =21.09%
Rainfall, P =1.00 inches
Rv =0.240 acres
WQV =0.272 acre-ft
=11,836 cf
1-YEAR TREATMENT VOLUME
Pre/Post Difference in 1-Year Volume
1-Year Treatment Volume =11,248 cf
=0.258 acre-ft
ASSOCIATED DEPTH OF 1-YEAR TREATMENT VOLUME IN POND
Water Quality Volume =11,836 cf Larger of two volumes above
Ks =12504
b =1.1172
NWSE =639.00 ft
Depth of WQV in Pond =0.95 ft
=11.42 inches
Elevation =639.95 ft Spillway must be set above this elevation
WATER QUALITY VOLUME CALCULATION
Project Name: Southstone Date:1/18/2018
Project Number: TAC-17000 Calculated By: J. Aldridge, PE
Facility ID:SWMF F
DRAWDOWN DESIGN
Using falling head
Orifice Diameter =1.75 inches
Number of Orifices =1
Orifice Coefficient, Cd =0.60
Ks =12504
b =1.1172
NWSE =639.00 ft
WQV =11,836
WQV Elevation in Pond =639.95 ft
Average Incremental Incremental
WSEL Storage Siphon Flow Flow Volume Time
[ft][cf][cfs][cfs][cf][sec]
639.95 11836 0.075
639.87 10688 0.072 0.073 1,148 15,624
639.79 9553 0.068 0.070 1,135 16,279
639.70 8432 0.064 0.066 1,121 17,046
639.62 7326 0.059 0.062 1,106 17,961
639.54 6238 0.055 0.057 1,088 19,083
639.45 5169 0.050 0.052 1,069 20,508
639.37 4123 0.044 0.047 1,046 22,409
639.29 3105 0.037 0.040 1,018 25,152
639.20 2121 0.029 0.033 984 29,690
639.12 1184 0.016 0.023 937 41,110
Drawdown Time =2.60 days 2-5 day drawdown required
DRAWDOWN DESIGN
Using average head
Average Head on Orifice =0.440 inches
Orifice Coefficient, Cd =0.60
Area of Orifice =0.017 sf
Flowrate, Q =0.053 cfs
Drawdown Time =2.57 days 2-5 day drawdown required
WATER QUALITY VOLUME DRAWDOWN CALCULATION
Project Name: Southstone Date:1/18/2018
Project Number: TAC-17000 Calculated By: J. Aldridge, PE
Facility ID:SWMF F
INPUT DATA
Inside Length =4.00 ft
Inside Width =4.00 ft
Wall Thickness =6.00 in
Standard Base Length =5.00 ft
Standard Base Width =5.00 ft
Standard Base Thickness =6.00 in
Inside Height of Riser =5.00 ft
Concrete Unit Weight =142.00 pcf Unit weight of manhole concrete is 142 pcf per NC Products
Outside Diameter of Barrel =30.00 in
Drain Pipe (if present) =8.00 in
TRASH RACK DISPLACEMENT
Bottom Length / Width =7.00 ft Calculation for truncated square pyramid
Top Length / Width =1.00 ft
Height =2.00 ft
Trash Rack Displacement =38.000 cf
CONCRETE PRESENT IN RISER STRUCTURE
Riser Walls =45.000 cf
Standard Base of Riser =12.500 cf
Less Opening for Barrel =2.454 cf
Less Opening for Drain Pipe =0.175 cf
Total Concrete Less Openings =54.871 cf
Weight of Concrete =7,792 lbs
AMOUNT OF WATER DISPLACED BY RISER STRUCTURE
Displacement by Concrete =54.871 cf
Displacement by Open Air =80.000 cf
Displacement by Trash Rack =38.000 cf
Total Water Displaced =172.871 cf
Weight of Water Displaced =10,787 lbs
RISER ANTI-FLOTATION CALCULATION
AMOUNT OF CONCRETE TO ADD TO RISER STRUCTURE
Safety Factor =1.15 Recommend 1.15 or higher
Add'l Weight for Bouyancy =4,614 lbs
Bouyant Weight of Concrete =79.60 pcf
Bouyant Weight w/ SF =69.22 pcf
Add'l Concrete to Add =66.653 cf
Less Standard Base =12.500 cf
New Base Design Required =79.153 cf
ANTI FLOTATION BLOCK DESIGN CALCULATIONS
AF Block Length =8.00 ft
AF Block Width =8.00 ft
AF Block Thickness =18.00 in
AF Block Provided =96.000 cf
Total Concrete Present =138.371 cf
Total Concrete Present =19,649 lbs
Project Name:Southstone Date:1/12/2018
Project Number:TAC-17000 Calculated By:J. Aldridge, PE
Facility ID:SWMF F
DESIGN OF RIPRAP OUTLET PROTECTION
Calculations based on NY DOT method - Pages 8.06.05 through 8.06.06 in NC Erosion Control Manual.
Flow, Q10-yr =7.90 cfs
Slope =1.32 %
Pipe Diameter, Do =24 in
=2.00 feet
Number of pipes =1
Pipe separation =0.00 feet
Manning's n =0.013
Zone from graph above =2
Outlet pipe diameter =24 in Length =12.00 ft
Outlet flowrate =7.90 cfs Width =6.00 ft
Outlet velocity =7.27 ft/sec Stone diameter =6.00 in
Material =Class B Thickness =22.00 in
Zone Material Diameter Thickness Length Width
1 Class A 3 9 4 x Do 3 x Do
2 Class B 6 22 6 x Do 3 x Do
3 Class I 13 22 8 x Do 3 x Do
4 Class I 13 22 8 x Do 3 x Do
5 Class II 23 27 10 x Do 3 x Do
6 Class II 23 27 10 x Do 3 x Do
7 Study Required
RIPRAP OUTLET PROTECTION
7.27 ft/sec
0
5
10
15
20
25
0 1 2 3 4 5 6 7 8 9 10Velocity(ft/sec)Pipe diameter (ft)
Figure 8.06.b.1
Zone 1
Zone 2
Zone 3
Zone 4
Zone 5
Zone 6 Zone 7
Storm Event: 1 year 24 hrLabel: SWMF F
Return Event: 1 yearsSubsection: Elevation-Area Volume Curve
Volume (Total)
(ft³)
Volume
(ft³)
A1+A2+sqr
(A1*A2)
(ft²)
Area
(ft²)
Planimeter
(ft²)
Elevation
(ft)
0.0000.0000.008,986.000.0639.00
2,671.0002,671.00032,057.2912,481.000.0639.25
12,436.0009,764.00039,056.2413,564.000.0640.00
15,872.0003,437.00041,242.7713,932.000.0640.25
26,741.00010,868.00043,472.5815,057.000.0641.00
42,566.00015,825.00047,475.5416,606.000.0642.00
59,969.00017,403.00052,208.4718,212.000.0643.00
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 1 year 24 hrLabel: SWMF F
Return Event: 1 yearsSubsection: Outlet Input Data
Requested Pond Water Surface Elevations
ft639.00Minimum (Headwater)
ft0.10Increment (Headwater)
ft643.00Maximum (Headwater)
Outlet Connectivity
E2
(ft)
E1
(ft)
OutfallDirectionOutlet IDStructure Type
643.00640.00CulvertForwardOrificeOrifice-Area
643.00641.50CulvertForwardRiserInlet Box
643.00639.00CulvertForwardSiphonOrifice-Circular
643.00636.50TWForwardCulvertCulvert-Circular
(N/A)(N/A)TailwaterTailwater Settings
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 1 year 24 hrLabel: SWMF F
Return Event: 1 yearsSubsection: Outlet Input Data
Structure ID: Culvert
Structure Type: Culvert-Circular
1Number of Barrels
in24.00Diameter
ft38.00Length
ft38.00Length (Computed Barrel)
ft/ft0.013Slope (Computed)
Outlet Control Data
0.013Manning's n
1Ke
0Kb
0Kr
ft0.00Convergence Tolerance
Inlet Control Data
Form 1Equation Form
0.0098K
2.0000M
0.0398C
0.6700Y
1T1 ratio (HW/D)
1T2 ratio (HW/D)
-1Slope Correction Factor
Use unsubmerged inlet control 0 equation below T1 elevation.
Use submerged inlet control 0 equation above T2 elevation
In transition zone between unsubmerged and submerged inlet
control,
interpolate between flows at T1 & T2...
ft638.81T1 Elevation ft³/s15.55T1 Flow
ft639.10T2 Elevation ft³/s17.77T2 Flow
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 1 year 24 hrLabel: SWMF F
Return Event: 1 yearsSubsection: Outlet Input Data
Structure ID: Riser
Structure Type: Inlet Box
1Number of Openings
ft641.50Elevation
ft²16.0Orifice Area
1Orifice Coefficient
ft16.00Weir Length
(ft^0.5)/s3.00Weir Coefficient
1K Reverse
0Manning's n
0Kev, Charged Riser
FalseWeir Submergence
FalseOrifice H to crest
Structure ID: Siphon
Structure Type: Orifice-Circular
1Number of Openings
ft639.00Elevation
in1.75Orifice Diameter
1Orifice Coefficient
Structure ID: Orifice
Structure Type: Orifice-Area
2Number of Openings
ft640.00Elevation
ft²1.0Orifice Area
ft640.50Top Elevation
ft640.25Datum Elevation
1Orifice Coefficient
Structure ID: TW
Structure Type: TW Setup, DS Channel
Free OutfallTailwater Type
Convergence Tolerances
30Maximum Iterations
ft0.01Tailwater Tolerance
(Minimum)
ft0.50Tailwater Tolerance
(Maximum)
ft0.01Headwater Tolerance
(Minimum)
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 1 year 24 hrLabel: SWMF F
Return Event: 1 yearsSubsection: Outlet Input Data
Convergence Tolerances
ft0.50Headwater Tolerance
(Maximum)
ft³/s0.001Flow Tolerance (Minimum)
ft³/s10.000Flow Tolerance (Maximum)
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 1 year 24 hrLabel: SWMF F
Return Event: 1 yearsSubsection: Composite Rating Curve
Composite Outflow Summary
Contributing StructuresConvergence Error
(ft)
Tailwater Elevation
(ft)
Flow
(ft³/s)
Water Surface
Elevation
(ft)
(no Q:
Orifice,Riser,Siphon,Culver
t)
0.00(N/A)0.00639.00
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.01639.10
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.03639.20
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.04639.30
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.04639.40
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.05639.50
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.06639.60
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.06639.70
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.07639.80
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.07639.90
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.08640.00
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)1.04640.10
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)2.01640.20
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)2.98640.30
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)3.94640.40
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)4.91640.50
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)5.79640.60
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)6.56640.70
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)7.25640.80
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)7.87640.90
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)8.45641.00
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)8.99641.10
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 1 year 24 hrLabel: SWMF F
Return Event: 1 yearsSubsection: Composite Rating Curve
Composite Outflow Summary
Contributing StructuresConvergence Error
(ft)
Tailwater Elevation
(ft)
Flow
(ft³/s)
Water Surface
Elevation
(ft)
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)9.49641.20
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)9.98641.30
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)10.45641.40
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)10.89641.50
Orifice,Riser,Siphon,Culver
t
0.00(N/A)12.83641.60
Orifice,Riser,Siphon,Culver
t
0.00(N/A)16.01641.70
Orifice,Riser,Siphon,Culver
t
0.00(N/A)19.98641.80
Orifice,Riser,Siphon,Culver
t
0.00(N/A)24.55641.90
Orifice,Riser,Siphon,Culver
t
0.00(N/A)27.37642.00
Orifice,Riser,Siphon,Culver
t
0.00(N/A)30.03642.10
Orifice,Riser,Siphon,Culver
t
0.00(N/A)32.23642.20
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)33.31642.30
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)33.68642.40
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)34.04642.50
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)34.40642.60
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)34.76642.70
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)35.12642.80
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)35.47642.90
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)35.82643.00
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 1 year 24 hrLabel: SWMF F (IN)
Return Event: 1 yearsSubsection: Level Pool Pond Routing Summary
Infiltration
No InfiltrationInfiltration Method
(Computed)
Initial Conditions
ft639.00Elevation (Water Surface,
Initial)
ft³0.000Volume (Initial)
ft³/s0.00Flow (Initial Outlet)
ft³/s0.00Flow (Initial Infiltration)
ft³/s0.00Flow (Initial, Total)
min1.00Time Increment
Inflow/Outflow Hydrograph Summary
ft³/s9.04Flow (Peak In)min720.00Time to Peak (Flow, In)
ft³/s0.50Flow (Peak Outlet)min871.00Time to Peak (Flow, Outlet)
ft640.04Elevation (Water Surface,
Peak)
ft³13,022.526Volume (Peak)
Mass Balance (ft³)
ft³0.000Volume (Initial)
ft³24,356.000Volume (Total Inflow)
ft³0.000Volume (Total Infiltration)
ft³11,759.000Volume (Total Outlet
Outflow)
ft³12,585.000Volume (Retained)
ft³-12.000Volume (Unrouted)
%0.0Error (Mass Balance)
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 2 yearLabel: SWMF F (IN)
Return Event: 2 yearsSubsection: Level Pool Pond Routing Summary
Infiltration
No InfiltrationInfiltration Method
(Computed)
Initial Conditions
ft639.00Elevation (Water Surface,
Initial)
ft³0.000Volume (Initial)
ft³/s0.00Flow (Initial Outlet)
ft³/s0.00Flow (Initial Infiltration)
ft³/s0.00Flow (Initial, Total)
min1.00Time Increment
Inflow/Outflow Hydrograph Summary
ft³/s9.60Flow (Peak In)min187.00Time to Peak (Flow, In)
ft³/s0.72Flow (Peak Outlet)min293.00Time to Peak (Flow, Outlet)
ft640.07Elevation (Water Surface,
Peak)
ft³13,336.412Volume (Peak)
Mass Balance (ft³)
ft³0.000Volume (Initial)
ft³17,551.000Volume (Total Inflow)
ft³0.000Volume (Total Infiltration)
ft³9,439.000Volume (Total Outlet
Outflow)
ft³8,107.000Volume (Retained)
ft³-5.000Volume (Unrouted)
%0.0Error (Mass Balance)
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 10 yearLabel: SWMF F (IN)
Return Event: 10 yearsSubsection: Level Pool Pond Routing Summary
Infiltration
No InfiltrationInfiltration Method
(Computed)
Initial Conditions
ft639.00Elevation (Water Surface,
Initial)
ft³0.000Volume (Initial)
ft³/s0.00Flow (Initial Outlet)
ft³/s0.00Flow (Initial Infiltration)
ft³/s0.00Flow (Initial, Total)
min1.00Time Increment
Inflow/Outflow Hydrograph Summary
ft³/s32.92Flow (Peak In)min186.00Time to Peak (Flow, In)
ft³/s7.90Flow (Peak Outlet)min210.00Time to Peak (Flow, Outlet)
ft640.91Elevation (Water Surface,
Peak)
ft³25,327.070Volume (Peak)
Mass Balance (ft³)
ft³0.000Volume (Initial)
ft³56,727.000Volume (Total Inflow)
ft³0.000Volume (Total Infiltration)
ft³48,537.000Volume (Total Outlet
Outflow)
ft³8,185.000Volume (Retained)
ft³-5.000Volume (Unrouted)
%0.0Error (Mass Balance)
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 25 yearLabel: SWMF F (IN)
Return Event: 25 yearsSubsection: Level Pool Pond Routing Summary
Infiltration
No InfiltrationInfiltration Method
(Computed)
Initial Conditions
ft639.00Elevation (Water Surface,
Initial)
ft³0.000Volume (Initial)
ft³/s0.00Flow (Initial Outlet)
ft³/s0.00Flow (Initial Infiltration)
ft³/s0.00Flow (Initial, Total)
min1.00Time Increment
Inflow/Outflow Hydrograph Summary
ft³/s45.70Flow (Peak In)min186.00Time to Peak (Flow, In)
ft³/s11.24Flow (Peak Outlet)min207.00Time to Peak (Flow, Outlet)
ft641.52Elevation (Water Surface,
Peak)
ft³34,745.794Volume (Peak)
Mass Balance (ft³)
ft³0.000Volume (Initial)
ft³78,462.000Volume (Total Inflow)
ft³0.000Volume (Total Infiltration)
ft³70,244.000Volume (Total Outlet
Outflow)
ft³8,214.000Volume (Retained)
ft³-5.000Volume (Unrouted)
%0.0Error (Mass Balance)
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
Storm Event: 100 yearLabel: SWMF F (IN)
Return Event: 100 yearsSubsection: Level Pool Pond Routing Summary
Infiltration
No InfiltrationInfiltration Method
(Computed)
Initial Conditions
ft639.00Elevation (Water Surface,
Initial)
ft³0.000Volume (Initial)
ft³/s0.00Flow (Initial Outlet)
ft³/s0.00Flow (Initial Infiltration)
ft³/s0.00Flow (Initial, Total)
min1.00Time Increment
Inflow/Outflow Hydrograph Summary
ft³/s66.49Flow (Peak In)min186.00Time to Peak (Flow, In)
ft³/s28.39Flow (Peak Outlet)min196.00Time to Peak (Flow, Outlet)
ft642.04Elevation (Water Surface,
Peak)
ft³43,201.068Volume (Peak)
Mass Balance (ft³)
ft³0.000Volume (Initial)
ft³113,141.000Volume (Total Inflow)
ft³0.000Volume (Total Infiltration)
ft³104,894.000Volume (Total Outlet
Outflow)
ft³8,243.000Volume (Retained)
ft³-5.000Volume (Unrouted)
%0.0Error (Mass Balance)
1/18/2018TAC17000.ppc
Jessie Mattingly, EISOUTHSTONE
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