20181476 Ver 1_Stormwater Impact Analysis_20181030

HOWARD
Stormwater Impact Analysis & Final Design of Stormwater Control Measures / October 2018

STORMWATER IMPACT ANALYSIS

creating experiences through experience 3430 Toringdon Way, Suite 110, Charlotte, NC 28277 / 704. 527. 0800

GENERAL DESCRIPTION

Located southeast of the intersection of Charlotte Highway (NC-21) and Interstate 77 in Troutman,
North Carolina, is the proposed development known as Howard. Proposed development on this site will
consist of the construction of over 200 residential homes and road extension of Crosstie Lane along
with the associated parking, sidewalks, utility improvements and stormwater management facilities.

The proposed development is located within the Yadkin Pee Dee River basin with stormwater runoff
from the proposed development draining into Weathers Creek. Per Town of Troutman regulations,
stormwater management on this site shall conform to the stormwater management performance
standards for development set forth in the Town of Troutman Unified Development Ordinance. The site
is required to provide peak runoff control for the 10- year storm. The applicable design requirements
are as follows:

Sec. 8.11.1 Comprehensive Stormwater Management Plan

D. High-density projects shall use wet detention ponds or other structural BMP’s, in accordance with the NC
DEQ Stormwater BMP Design Manual, to control and treat runoff from the development. If the
development also lies within the Watershed Overlay District, additional requirements may apply as to
stormwater management (reference Section 3.5).

To address applicable stormwater management requirements, two stormwater control measures are
proposed to treat runoff and manage peak runoff rates. Please refer to the appropriate section of this
report for additional information.

CALCULATION METHODOLOGY

> Rainfall data for the analysis was taken from the NOAA Atlas 14. Please reference the
precipitation information section within this report for additional information.
> Using maps contained within the NRCS Web Soil Survey, the on-site soils were determined to be
hydrologic soil group (HSG) ‘B’ and ‘C’ 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 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.

STORMWATER IMPACT ANALYSIS

creating experiences through experience 2 of 2

> 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.
> PondPack Version V8i was used in determining the pre- & post-development peak flow rates for
the 2- and 10-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:
The proposed project will result in a significant increase in peak flow rates to downstream properties.
To mitigate these impacts, the proposed stormwater management facilities have been sized such that
post-development peak flow rates are no greater than pre-development levels in the 2- and 10-year
storm events on site.

Water Quality Requirements:
The proposed facilities are designed in accordance with the NC DEQ Stormwater BMP Design Manual
and shall meet applicable water quality requirements.

CONCLUSION

If the development on this tract is built as proposed within this report, then the requirements set forth
in Town of Troutman regulations 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.
4 PRECIPITATION DATA
1 SUMMARY OF RESULTS
2 MISCELLANEOUS SITE INFORMATION
5 PRE-DEVELOPMENT HYDROLOGIC CALCULATIONS
8 DESIGN OF STORMWATER CONTROL MEASURE B
6 POST-DEVELOPMENT HYDROLOGIC
CALCULATIONS
7 DESIGN OF STORMWATER CONTROL MEASURE A
3 WATERSHED SOILS INFORMATION
HOWARD
RYN-18000

SUMMARY OF RESULTS

Project Name: Howard Property Date: 10/5/2018
Project Number:RYN-18000 Calculated By: J. Aldridge, PE
RELEASE RATE MANAGEMENT RESULTS
Pre-Dev Post-Dev
Return Period [cfs][cfs]% Increase
2-Year 24.58 19.62 -20%
10-Year 80.39 69.38 -14%
SUMMARY OF RESULTS
POINT OF ANALYSIS #1
Project Name: Howard Property Date: 10/5/2018
Project Number:RYN-18000 Calculated By: J. Aldridge, PE
STORMWATER CONTROL MEASURE 'A' SUMMARY
Design Drainage Area =65.73 acres
Design Impervious Area =16.30 acres
% Impervious =24.8%
Water Quality Volume =65,196 cf
Top of Dam =839.00 ft
NWSE =832.50 ft
Average Depth =3.88 ft
Main Pool SA Required =23,825 sf
Main Pool SA Provided =41,473 sf
Siphon Diameter =5.00 in
Siphon Elevation =832.50 ft
WQV Elevation =833.52 ft
Drawdown Time =2.62 days
Secondary Orifice =(3) 3' x 1'
Orifice Elevation =833.75 ft
Riser =5' x 5'
Riser Crest =835.50 ft
Barrel Diameter =36 in
Invert In =832.00 ft
Invert Out =831.50 ft
Length =48 ft
% Slope =1.04%
STORMWATER CONTROL MEASURE 'A' ROUTING RESULTS
Inflow Outflow Max WSE Freeboard
Return Period [cfs][cfs][ft][ft]
2-Year 94.65 10.74 834.09 4.91
10-Year 186.38 31.83 835.51 3.49
25-Year 241.22 53.72 836.33 2.67
100-Year 320.10 68.97 837.78 1.22
SUMMARY OF RESULTS
Project Name: Howard Property Date: 10/5/2018
Project Number:RYN-18000 Calculated By: J. Aldridge, PE
STORMWATER CONTROL MEASURE 'B' SUMMARY
Design Drainage Area =18.10 acres
Design Impervious Area =7.07 acres
% Impervious =39.1%
Water Quality Volume =26,392 cf
Top of Dam =830.00 ft
NWSE =825.00 ft
Average Depth =4.81 ft
Main Pool SA Required =8,630 sf
Main Pool SA Provided =10,288 sf
Siphon Diameter =2.50 in
Siphon Elevation =825.00 ft
WQV Elevation =826.57 ft
Drawdown Time =2.11 days
Secondary Orifice =(3) 3' x 0.75'
Orifice Elevation =826.75 ft
Riser =5' x 5'
Riser Crest =828.00 ft
Barrel Diameter =36 in
Invert In =817.75 ft
Invert Out =817.00 ft
Length =67 ft
% Impervious =1.12%
STORMWATER CONTROL MEASURE 'B' ROUTING RESULTS
Inflow Outflow Max WSE Freeboard
Return Period [cfs][cfs][ft][ft]
2-Year 34.82 7.88 827.04 2.96
10-Year 62.98 27.97 827.85 2.15
25-Year 78.38 44.91 828.29 1.71
100-Year 99.87 72.49 828.66 1.34
SUMMARY OF RESULTS
HOWARD
RYN-18000

MISCELLANEOUS SITE INFORMATION

NC Center for Geographic Information & Analysis, Esri, HERE, Garmin, ©OpenStreetMap contributors
0 1,000 2,000500Feet1 inch = 1,000 feet
¯HOWARD PROPERTY
SITE AERIAL MAPPROJECT #: RYN-18000TROUTMAN, NORTH CAROLINA
Copyright:© 2013 National Geographic Society, i-cubed
0 2,000 4,0001,000 Feet1 inch = 2,000 feet
¯HOWARD PROPERTY
USGS TOPO MAPPROJECT #: RYN-18000TROUTMAN, NORTH CAROLINA
USGS The National Map: Orthoimagery. Data refreshed October 2017.
National Flood Hazard Layer FIRMette
0 500 1,000 1,500 2,000250Feet
Ü80°51'3.86"W 35°40'18.36"N 80°50'26.40"W 35°39'49.13"N
SEE FIS REPORT FOR DETAILED LEGEND AND INDEX MAP FOR FIRM PANEL LAYOUT
SPECIAL FLOODHAZARD AR EAS
Without Base Flood Elevation (BFE)Zone A, V, A99With BFE or Depth Zone AE, AO, AH, VE, AR
Regulator y Floodway
0.2% Annual Chance Flood Hazard, Areasof 1% annual chance flood with averagedepth less than one foot or with drainageareas of less than one square mile Zone X
Future Conditions 1% AnnualChance Flood Hazard Zone XArea with Reduced Flood Risk due toLevee. See Notes.Zone X
Area with Flood Risk due to Levee Zone D
NO SCREE N Area of Minimal Flood Hazard Zone X
Area of Undetermined Flood Hazard Zone D
Channel, Culver t, or Storm SewerLevee, Dike, or Floodwall
Cross Sections with 1% Annual Chance17.5 Water Surface ElevationCoastal Transect
Coastal Transect BaselineProfile BaselineHydrographic Feature
Base Flood Elevation Line (BFE)
Effective LOMRs
Limit of StudyJurisdiction Boundar y
Digital Data Available
No Digital Data Available
Unmapped
This map complies with FEMA's standards for the use of digital flood maps if it is not void as described below. The basemap shown complies with FEMA's basemap accuracy standards
The flood hazard information is derived directly from theauthoritative NFHL web services provided by FEMA. This mapwas exported on 10/4/2018 at 7:35:34 AM and does notreflect changes or amendments subsequent to this date andtime. The NFHL and effective information may change orbecome superseded by new data over time.
This map image is void if the one or more of the following mapelements do not appear: basemap imagery, flood zone labels,legend, scale bar, map creation date, community identifiers,FIRM panel number, and FIRM effective date. Map images forunmapped and unmodernized areas cannot be used forregulatory purposes.
Legend
OTHER AREAS OFFLOOD HAZARD
OTHER AREAS
GENERALSTRUCTURES
OTHERFEATURES
MAP PANELS
8
1:6,000
B 20.2
The pin displayed on the map is an approximate point selected by the user and does not represent an authoritative proper ty location.
HOWARD
RYN-18000

WATERSHED SOILS INFORMATION

Hydrologic Soil Group—Iredell County, North Carolina
(PRE-SUB)
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
8/22/2018
Page 1 of 439463003946400394650039466003946700394680039469003947000394710039472003947300394740039475003947600394770039478003946300394640039465003946600394670039468003946900394700039471003947200394730039474003947500394760039477003947800513500513600513700513800513900514000514100514200514300514400514500514600
513500 513600 513700 513800 513900 514000 514100 514200 514300 514400 514500 514600
35° 40' 27'' N 80° 51' 4'' W35° 40' 27'' N80° 50' 17'' W35° 39' 37'' N
80° 51' 4'' W35° 39' 37'' N
80° 50' 17'' WN
Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 17N WGS84
0 350 700 1400 2100
Feet
0 100 200 400 600
Meters
Map Scale: 1:7,610 if printed on A portrait (8.5" x 11") sheet.
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
1:12,000.
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: Iredell County, North Carolina
Survey Area Data: Version 22, Sep 26, 2017
Soil map units are labeled (as space allows) for map scales
1:50,000 or larger.
Date(s) aerial images were photographed: Jul 18, 2011—Oct 25,
2017
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—Iredell County, North Carolina
(PRE-SUB)
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
8/22/2018
Page 2 of 4
Hydrologic Soil Group
Map unit symbol Map unit name Rating Acres in AOI Percent of AOI
ApB Appling sandy loam, 2 to
6 percent slopes
B 3.3 3.0%
CeB2 Cecil sandy clay loam, 2
to 6 percent slopes,
moderately eroded
B 23.7 21.7%
CeC2 Cecil sandy clay loam, 6
to 10 percent slopes,
moderately eroded
B 26.5 24.2%
ChA Chewacla loam, 0 to 2
percent slopes,
frequently flooded
B/D 10.2 9.4%
DrB Dorian fine sandy loam,
0 to 6 percent slopes,
rarely flooded
C 2.5 2.3%
MaD4 Madison-Udorthents
complex, 2 to 15
percent slopes, gullied
B 19.3 17.7%
PcC2 Pacolet sandy clay
loam, 6 to 10 percent
slopes, moderately
eroded
B 21.8 20.0%
PcD2 Pacolet sandy clay
loam, 10 to 15 percent
slopes, moderately
eroded
B 1.8 1.6%
Totals for Area of Interest 109.2 100.0%
Hydrologic Soil Group—Iredell County, North Carolina PRE-SUB
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
8/22/2018
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—Iredell County, North Carolina PRE-SUB
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
8/22/2018
Page 4 of 4
HOWARD
RYN-18000

PRECIPITATION DATA

Element Details
30ID Notes
TroutmanLabel
2 year
2 yearLabel min5.000Increment
years2Return Event min1,440.000End Time
min0.000Start Time CumulativeStorm Event Depth Type
2 year
Depth
(in)
Depth
(in)
Depth
(in)
Depth
(in)
Depth
(in)
Time
(min)
0.0150.0110.0070.0040.0000.000
0.0330.0290.0260.0220.01825.000
0.0520.0480.0440.0400.03750.000
0.0700.0660.0630.0590.05575.000
0.0880.0850.0810.0770.074100.000
0.1070.1030.0990.0960.092125.000
0.1250.1210.1180.1140.110150.000
0.1440.1400.1360.1330.129175.000
0.1620.1580.1550.1510.147200.000
0.1800.1770.1730.1690.166225.000
0.1990.1950.1910.1880.184250.000
0.2170.2130.2100.2060.202275.000
0.2360.2320.2280.2250.221300.000
0.2540.2500.2470.2430.239325.000
0.2780.2720.2650.2610.258350.000
0.3110.3040.2980.2910.285375.000
0.3430.3370.3300.3240.317400.000
0.3760.3690.3630.3560.350425.000
0.4090.4020.3960.3890.382450.000
0.4410.4350.4280.4220.415475.000
0.4740.4670.4610.4540.448500.000
0.5120.5000.4930.4870.480525.000
0.5730.5610.5490.5370.524550.000
0.6340.6220.6100.5980.586575.000
0.6960.6830.6710.6590.647600.000
0.7500.7400.7300.7200.708625.000
0.8230.8020.7800.7700.760650.000
0.9830.9100.8880.8670.845675.000
1.8771.4291.2031.1301.056700.000
2.3972.3242.2502.1772.104725.000
2.5572.5352.5132.4922.470750.000
2.6302.6202.6102.6002.578775.000
2.6842.6722.6602.6502.640800.000
2.7462.7332.7212.7092.697825.000
2.8072.7942.7822.7702.758850.000
2.8682.8562.8432.8312.819875.000
2.9062.9002.8932.8872.880900.000
2.9392.9322.9262.9192.913925.000
10/4/2018RYN18000.ppc
K. GALLTHOWARD
2 year
Depth
(in)
Depth
(in)
Depth
(in)
Depth
(in)
Depth
(in)
Time
(min)
2.9712.9652.9582.9522.945950.000
3.0042.9982.9912.9842.978975.000
3.0373.0303.0243.0173.0111,000.000
3.0693.0633.0563.0503.0431,025.000
3.1023.0953.0893.0823.0761,050.000
3.1263.1223.1193.1153.1081,075.000
3.1443.1413.1373.1333.1301,100.000
3.1633.1593.1553.1523.1481,125.000
3.1813.1783.1743.1703.1671,150.000
3.2003.1963.1923.1893.1851,175.000
3.2183.2143.2113.2073.2031,200.000
3.2363.2333.2293.2253.2221,225.000
3.2553.2513.2483.2443.2401,250.000
3.2733.2703.2663.2623.2591,275.000
3.2923.2883.2843.2813.2771,300.000
3.3103.3063.3033.2993.2951,325.000
3.3283.3253.3213.3173.3141,350.000
3.3473.3433.3403.3363.3321,375.000
3.3653.3623.3583.3543.3511,400.000
(N/A)3.3803.3763.3733.3691,425.000
10 year
10 yearLabel min5.000Increment
years10Return Event min1,440.000End Time
min0.000Start Time CumulativeStorm Event Depth Type
10 year
Depth
(in)
Depth
(in)
Depth
(in)
Depth
(in)
Depth
(in)
Time
(min)
0.0230.0170.0110.0060.0000.000
0.0510.0450.0390.0340.02825.000
0.0790.0730.0680.0620.05650.000
0.1070.1010.0960.0900.08475.000
0.1350.1290.1240.1180.113100.000
0.1630.1580.1520.1460.141125.000
0.1910.1860.1800.1740.169150.000
0.2190.2140.2080.2020.197175.000
0.2480.2420.2360.2310.225200.000
0.2760.2700.2640.2590.253225.000
0.3040.2980.2930.2870.281250.000
0.3320.3260.3210.3150.309275.000
0.3600.3540.3490.3430.338300.000
0.3880.3820.3770.3710.366325.000
0.4240.4150.4050.3990.394350.000
0.4730.4630.4540.4440.434375.000
0.5220.5120.5020.4920.483400.000
10/4/2018RYN18000.ppc
K. GALLTHOWARD
10 year
Depth
(in)
Depth
(in)
Depth
(in)
Depth
(in)
Depth
(in)
Time
(min)
0.5700.5610.5510.5410.531425.000
0.6190.6090.5990.5900.580450.000
0.6670.6580.6480.6380.629475.000
0.7160.7060.6970.6870.677500.000
0.7730.7550.7450.7360.726525.000
0.8620.8440.8260.8080.791550.000
0.9510.9330.9150.8970.879575.000
1.0391.0221.0040.9860.968600.000
1.1251.1081.0921.0751.057625.000
1.2421.2081.1751.1581.142650.000
1.4911.3751.3421.3081.275675.000
2.7122.1321.8371.7221.606700.000
3.4693.3543.2383.1233.007725.000
3.7183.6853.6523.6183.585750.000
3.8353.8183.8023.7853.752775.000
3.9213.9033.8853.8683.852800.000
4.0093.9923.9743.9563.938825.000
4.0984.0814.0634.0454.027850.000
4.1874.1694.1524.1344.116875.000
4.2444.2344.2244.2154.205900.000
4.2934.2834.2734.2634.254925.000
4.3414.3314.3224.3124.302950.000
4.3904.3804.3704.3614.351975.000
4.4384.4294.4194.4094.3991,000.000
4.4874.4774.4684.4584.4481,025.000
4.5364.5264.5164.5064.4971,050.000
4.5724.5664.5614.5554.5451,075.000
4.6004.5944.5894.5834.5781,100.000
4.6284.6234.6174.6114.6061,125.000
4.6564.6514.6454.6394.6341,150.000
4.6844.6794.6734.6684.6621,175.000
4.7134.7074.7014.6964.6901,200.000
4.7414.7354.7294.7244.7181,225.000
4.7694.7634.7584.7524.7461,250.000
4.7974.7914.7864.7804.7741,275.000
4.8254.8194.8144.8084.8031,300.000
4.8534.8484.8424.8364.8311,325.000
4.8814.8764.8704.8644.8591,350.000
4.9094.9044.8984.8934.8871,375.000
4.9384.9324.9264.9214.9151,400.000
(N/A)4.9604.9544.9494.9431,425.000
25 year
25 yearLabel min5.000Increment
years25Return Event min1,440.000End Time
min0.000Start Time CumulativeStorm Event Depth Type
10/4/2018RYN18000.ppc
K. GALLTHOWARD
25 year
Depth
(in)
Depth
(in)
Depth
(in)
Depth
(in)
Depth
(in)
Time
(min)
0.0270.0200.0130.0070.0000.000
0.0610.0540.0470.0400.03425.000
0.0940.0880.0810.0740.06750.000
0.1280.1210.1150.1080.10175.000
0.1620.1550.1480.1410.135100.000
0.1950.1890.1820.1750.168125.000
0.2290.2220.2160.2090.202150.000
0.2630.2560.2490.2420.236175.000
0.2960.2900.2830.2760.269200.000
0.3300.3230.3170.3100.303225.000
0.3640.3570.3500.3440.337250.000
0.3970.3910.3840.3770.370275.000
0.4310.4240.4180.4110.404300.000
0.4650.4580.4510.4450.438325.000
0.5090.4970.4850.4780.472350.000
0.5680.5560.5440.5320.520375.000
0.6270.6150.6030.5910.579400.000
0.6860.6740.6620.6500.638425.000
0.7450.7330.7210.7090.698450.000
0.8040.7920.7800.7680.757475.000
0.8630.8510.8390.8270.816500.000
0.9310.9100.8980.8860.875525.000
1.0381.0170.9960.9740.953550.000
1.1451.1241.1031.0811.060575.000
1.2521.2311.2091.1881.167600.000
1.3601.3381.3171.2951.274625.000
1.5081.4671.4251.4031.382650.000
1.8151.6751.6331.5921.550675.000
3.2072.5642.2352.0951.955700.000
4.0953.9553.8153.6753.535725.000
4.4024.3604.3184.2774.235750.000
4.5504.5284.5074.4854.443775.000
4.6584.6364.6154.5934.572800.000
4.7654.7434.7224.7014.679825.000
4.8724.8504.8294.8084.786850.000
4.9794.9574.9364.9144.893875.000
5.0475.0355.0245.0125.000900.000
5.1065.0945.0835.0715.059925.000
5.1655.1535.1425.1305.118950.000
5.2245.2135.2015.1895.177975.000
5.2835.2725.2605.2485.2361,000.000
5.3425.3315.3195.3075.2951,025.000
5.4015.3905.3785.3665.3541,050.000
5.4455.4385.4325.4255.4131,075.000
5.4795.4725.4655.4595.4521,100.000
5.5135.5065.4995.4925.4861,125.000
5.5465.5405.5335.5265.5191,150.000
5.5805.5735.5665.5605.5531,175.000
10/4/2018RYN18000.ppc
K. GALLTHOWARD
25 year
Depth
(in)
Depth
(in)
Depth
(in)
Depth
(in)
Depth
(in)
Time
(min)
5.6145.6075.6005.5935.5871,200.000
5.6475.6415.6345.6275.6201,225.000
5.6815.6745.6685.6615.6541,250.000
5.7155.7085.7015.6945.6881,275.000
5.7485.7425.7355.7285.7211,300.000
5.7825.7755.7695.7625.7551,325.000
5.8165.8095.8025.7955.7891,350.000
5.8495.8435.8365.8295.8221,375.000
5.8835.8765.8705.8635.8561,400.000
(N/A)5.9105.9035.8975.8901,425.000
100 year
100 yearLabel min5.000Increment
years100Return Event min1,440.000End Time
min0.000Start Time CumulativeStorm Event Depth Type
100 year
Depth
(in)
Depth
(in)
Depth
(in)
Depth
(in)
Depth
(in)
Time
(min)
0.0340.0250.0170.0080.0000.000
0.0760.0670.0590.0500.04225.000
0.1180.1090.1010.0920.08450.000
0.1600.1510.1430.1340.12675.000
0.2020.1930.1850.1760.168100.000
0.2440.2350.2270.2180.210125.000
0.2860.2770.2690.2600.252150.000
0.3280.3190.3110.3030.294175.000
0.3700.3610.3530.3450.336200.000
0.4120.4030.3950.3870.378225.000
0.4540.4450.4370.4290.420250.000
0.4960.4870.4790.4710.462275.000
0.5380.5290.5210.5130.504300.000
0.5800.5710.5630.5550.546325.000
0.6360.6200.6050.5970.588350.000
0.7130.6980.6820.6670.651375.000
0.7900.7750.7590.7440.728400.000
0.8670.8520.8360.8210.805425.000
0.9440.9290.9130.8980.883450.000
1.0211.0060.9900.9750.960475.000
1.0981.0831.0681.0521.037500.000
1.1871.1601.1451.1291.114525.000
1.3231.2961.2691.2421.214550.000
1.4591.4321.4051.3781.351575.000
1.5961.5681.5411.5141.487600.000
1.7501.7171.6831.6501.623625.000
1.9581.9041.8501.8171.783650.000
10/4/2018RYN18000.ppc
K. GALLTHOWARD
100 year
Depth
(in)
Depth
(in)
Depth
(in)
Depth
(in)
Depth
(in)
Time
(min)
2.3562.1752.1212.0672.013675.000
3.9943.2652.8992.7182.537700.000
5.0844.9034.7224.5414.359725.000
5.4825.4285.3735.3195.265750.000
5.6905.6575.6235.5905.536775.000
5.8445.8175.7905.7575.723800.000
5.9815.9535.9265.8995.872825.000
6.1176.0896.0626.0356.008850.000
6.2536.2266.1986.1716.144875.000
6.3426.3266.3116.2956.280900.000
6.4196.4036.3886.3736.357925.000
6.4966.4806.4656.4506.434950.000
6.5736.5586.5426.5276.511975.000
6.6506.6356.6196.6046.5881,000.000
6.7276.7126.6966.6816.6651,025.000
6.8046.7896.7736.7586.7431,050.000
6.8606.8526.8436.8356.8201,075.000
6.9026.8946.8856.8776.8691,100.000
6.9446.9366.9276.9196.9111,125.000
6.9866.9786.9696.9616.9531,150.000
7.0287.0207.0117.0036.9951,175.000
7.0707.0627.0537.0457.0371,200.000
7.1127.1047.0957.0877.0791,225.000
7.1547.1467.1387.1297.1211,250.000
7.1967.1887.1807.1717.1631,275.000
7.2387.2307.2227.2137.2051,300.000
7.2807.2727.2647.2557.2471,325.000
7.3227.3147.3067.2977.2891,350.000
7.3647.3567.3487.3397.3311,375.000
7.4067.3987.3907.3817.3731,400.000
(N/A)7.4407.4327.4237.4151,425.000
10/4/2018RYN18000.ppc
K. GALLTHOWARD
100 year 25 year 10 year 2 yearDepth (in)7.500
6.875
6.250
5.625
5.000
4.375
3.750
3.125
2.500
1.875
1.250
0.625
0.000
Time (min)
1,400.0001,200.0001,000.000800.000600.000400.000200.0000.000
10/4/2018RYN18000.ppc
K. GALLTHOWARD
HOWARD
RYN-18000

PRE-DEVELOPMENT HYDROLOGIC
CALCULATIONS

Project Name:Howard Date:10/4/2018
Project Number:RYN-18000 Calculated By:K. Gallt
INPUT SUMMARY
Total Area
Subbasin ID Impervious Open Wooded Pond Total Impervious Open Wooded Pond Total [acres]SCS CN Tc [min]
1 0.00 12.12 62.77 0.00 74.89 0.00 30.06 4.20 0.00 34.26 109.14 60 33.28
Totals 0.00 12.12 62.77 0.00 74.89 0.00 30.06 4.20 0.00 34.26 109.14
PRE DEVELOPMENT HYDROLOGIC SUMMARY
Onsite Area [acres]Offsite Area [acres]
Project Name:Howard Date:10/4/2018
Project Number:RYN-18000 Calculated By:K. Gallt
Subbasin ID:1
SCS CURVE NUMBER
(REF: TR-55 and NRCS Web Soil Survey).
HSG Impervious Open Wooded Pond
A 98 39 30 100
B 98 61 55 100
C 98 74 70 100
D 98 80 77 100
HSG 'A' =0%
HSG 'B' =89%
HSG 'C' =2%
HSG 'D' =9%
Cover Composite
Condition SCS CN
Impervious 98
Open 63
Wooded 58
Pond 100
WATERSHED BREAKDOWN
Composite Area Area
SCS CN [sf][acres]
98 0 0.00
63 528,047 12.12
58 2,734,060 62.77
100 0 0.00
98 0 0.00
63 1,309,264 30.06
58 182,958 4.20
100 0 0.00
Total Area =4,754,329 sf
=109.14 acres
Composite SCS CN =60
% Impervious =0.00%
TIME OF CONCENTRATION
(REF: SCS Segmental Approach, TR-55).
Segment 1: Overland Flow Segment 2: Concentrated Flow
Length =100 ft Length =654 ft
Upstream Elevation =930.00 ft Upstream Elevation =925.50 ft
Downstream Elevation =925.50 ft Downstream Elevation =902.00 ft
Height =4.50 ft Height =23.50 ft
Slope =0.0450 ft/ft Slope =0.0359 ft/ft
Manning's n =0.24 dense grasses Paved?No
P (2-year/24-hour) =3.38 inches (Troutman, NC)Velocity =3.06 ft/sec
Segment Time =10.04 minutes Segment Time =3.56 minutes
Segment 3: Channel Flow
Length =5909 ft
Upstream Elevation =902.00 ft
Downstream Elevation =810.00 ft
Height =92.00 ft
Slope =0.0156 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 =5.00 ft/sec
Segment Time =19.68 minutes
Offsite Pond -
PRE DEVELOPMENT HYDROLOGIC CALCULATIONS
Offsite Impervious -
Offsite Open Assume good condition
Offsite Wooded Assume good condition
Comments
-
Assume good condition
Assume good condition
-
Contributing Area
Onsite Impervious
Onsite Open
Onsite Wooded
Onsite Pond
Comments
-
Assume good condition
Assume good condition
-
10/5/2018RYN18000.ppc
K. GALLTHOWARD
Subsection: Master Network Summary
Catchments Summary
Peak Flow
(ft³/s)
Time to Peak
(min)
Hydrograph
Volume
(ac-ft)
Return
Event
(years)
ScenarioLabel
24.58750.0004.3002Pre 2 yearSUB 1
80.39744.00011.46710Pre 10 yearSUB 1
119.13741.00016.73725Pre 25 yearSUB 1
182.35741.00026.263100Pre100 yearSUB 1
Node Summary
Peak Flow
(ft³/s)
Time to Peak
(min)
Hydrograph
Volume
(ac-ft)
Return
Event
(years)
ScenarioLabel
24.58750.0004.3002Pre 2 yearPOA 1
80.39744.00011.46710Pre 10 yearPOA 1
119.13741.00016.73725Pre 25 yearPOA 1
182.35741.00026.263100Pre100 yearPOA 1
10/5/2018RYN18000.ppc
K. GALLTHOWARD
HOWARD
RYN-18000

POST-DEVELOPMENT HYDROLOGIC
CALCULATIONS

Project Name:Howard Property Date:10/5/2018
Project Number:RYN-18000 Calculated By:K. Gallt
INPUT SUMMARY
Total Area
Subbasin ID Impervious Open Wooded Pond Total Impervious Open Wooded Pond Total [acres]SCS CN Tc [min]
1 To SWMF A 16.30 17.91 0.00 1.34 35.55 0.00 29.42 0.77 0.00 30.18 65.73 71 5.00
1 To SWMF B 7.08 7.85 0.00 0.37 15.30 0.00 0.58 2.09 0.00 2.67 17.97 76 5.00
1 Bypass 1.19 17.14 5.71 0.00 24.04 0.00 0.00 1.23 0.00 1.23 25.27 61 25.80
Unanalyzed 0.00 0.00 0.00 0.00 0.00 0.00 0.17 0.00 0.00 0.17 0.17 61 15.48
Totals 24.57 42.90 5.71 1.71 74.89 0.00 30.17 4.09 0.00 34.26 109.14
Onsite Area [acres]Offsite Area [acres]
POST DEVELOPMENT HYDROLOGIC SUMMARY
Project Name: Howard Property Date: 10/5/2018
Project Number:RYN-18000 Calculated By: K. Gallt
Subbasin ID:1 To SCM A
SCS CURVE NUMBER
(REF: TR-55 and NRCS Web Soil Survey).
HSG Impervious Open Wooded Pond
A 98 39 30 100
B 98 61 55 100
C 98 74 70 100
D 98 80 77 100
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
ONSITE IMPERVIOUS BREAKDOWN
Imp per Lot Imp Area
# of Lots [sf] [sf]
136.75 3,650 499,138
- - 211,060
Total Onsite Impervious Area =710,198 sf
WATERSHED BREAKDOWN
Composite Area Area
SCS CN [sf][acres]
98 710,198 16.30
61 779,959 17.91
55 0 0.00
100 58,506 1.34
98 0 0.00
61 1,281,319 29.42
55 33,429 0.77
100 0 0.00
Total Area =2,863,410 sf
=65.73 acres
Composite SCS CN =71
% Impervious =24.8%
TIME OF CONCENTRATION
(REF: SCS Segmental Approach, TR-55).
Time of Concentration =5.00 minutes
POST DEVELOPMENT HYDROLOGIC CALCULATIONS
Comments
-
Assume good condition
Offsite Open Assume good condition
Assume good condition
-
Contributing Area Comments
Contributing Area
Lot Impervious
Measured Impervious
Offsite Pond -
Onsite Pond -
Onsite Impervious -
Onsite Open Assume good condition
Onsite Wooded Assume good condition
Offsite Wooded Assume good condition
Offsite Impervious -
Project Name: Howard Property Date: 10/5/2018
Project Number:RYN-18000 Calculated By: K. Gallt
Subbasin ID:1 To SCM B
SCS CURVE NUMBER
(REF: TR-55 and NRCS Web Soil Survey).
HSG Impervious Open Wooded Pond
A 98 39 30 100
B 98 61 55 100
C 98 74 70 100
D 98 80 77 100
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
ONSITE IMPERVIOUS BREAKDOWN
Imp per Lot Imp Area
# of Lots [sf] [sf]
59.75 3,650 218,088
- - 90,151
Total Onsite Impervious Area =308,239 sf
WATERSHED BREAKDOWN
Composite Area Area
SCS CN [sf] [acres]
98 308,239 7.08
61 342,156 7.85
55 0 0.00
100 15,967 0.37
98 0 0.00
61 25,303 0.58
55 91,145 2.09
100 0 0.00
Total Area =782,809 sf
=17.97 acres
Composite SCS CN =76
% Impervious =39.4%
TIME OF CONCENTRATION
(REF: SCS Segmental Approach, TR-55).
Time of Concentration =5.00 minutes
Assume good condition
POST DEVELOPMENT HYDROLOGIC CALCULATIONS
Comments
-
Assume good condition
-
Contributing Area Comments
Onsite Impervious -
Onsite Open Assume good condition
Contributing Area
Lot Impervious
Measured Impervious
Onsite Wooded Assume good condition
Onsite Pond -
Offsite Impervious -
Offsite Pond -
Offsite Open Assume good condition
Offsite Wooded Assume good condition
Project Name: Howard Property Date: 10/5/2018
Project Number:RYN-18000 Calculated By: K. Gallt
Subbasin ID:1 Bypass
SCS CURVE NUMBER
(REF: TR-55 and NRCS Web Soil Survey).
HSG Impervious Open Wooded Pond
A 98 39 30 100
B 98 61 55 100
C 98 74 70 100
D 98 80 77 100
HSG 'A' =0%
HSG 'B' =97%
HSG 'C' =3%
HSG 'D' =0%
Cover Composite
Condition SCS CN
Impervious 98
Open 61
Wooded 55
Pond 100
ONSITE IMPERVIOUS BREAKDOWN
Imp per Lot Imp Area
# of Lots [sf] [sf]
25.50 3,650 93,075
- - 53,196
Total Onsite Impervious Area =146,271 sf
WATERSHED BREAKDOWN
Composite Area Area
SCS CN [sf][acres]
98 51,981 1.19
61 746,532 17.14
55 248,569 5.71
100 0 0.00
98 0 0.00
61 0 0.00
55 53,588 1.23
100 0 0.00
Total Area =1,100,670 sf
=25.27 acres
Composite SCS CN =61
% Impervious =4.7%
TIME OF CONCENTRATION
(REF: SCS Segmental Approach, TR-55).
Segment 1: Overland Flow Segment 2: Concentrated Flow
Length =100 ft Length =303 ft
Upstream Elevation =858.50 ft Upstream Elevation =851.00 ft
Downstream Elevation =851.00 ft Downstream Elevation =831.00 ft
Height =7.50 ft Height =20.00 ft
Slope =0.0750 ft/ft Slope =0.0660 ft/ft
Manning's n =0.24 dense grasses Paved?No
P (2-year/24-hour) =3.38 inches (Troutman, NC) Velocity =4.15 ft/sec
Segment Time =8.18 minutes Segment Time =1.22 minutes
Segment 3: Channel Flow
Length =3478 ft
Assume good condition
POST DEVELOPMENT HYDROLOGIC CALCULATIONS
Comments
-
Assume good condition
-
Contributing Area Comments
Onsite Impervious -
Onsite Open Assume good condition
Contributing Area
Lot Impervious
Measured Impervious
Onsite Wooded Assume good condition
Onsite Pond -
Offsite Impervious -
Offsite Pond -
Offsite Open Assume good condition
Offsite Wooded Assume good condition
Project Name: Howard Property Date: 10/5/2018
Project Number:RYN-18000 Calculated By: K. Gallt
Subbasin ID:Unanalyzed
SCS CURVE NUMBER
(REF: TR-55 and NRCS Web Soil Survey).
HSG Impervious Open Wooded Pond
A 98 39 30 100
B 98 61 55 100
C 98 74 70 100
D 98 80 77 100
HSG 'A' =0%
HSG 'B' =97%
HSG 'C' =3%
HSG 'D' =0%
Cover Composite
Condition SCS CN
Impervious 98
Open 61
Wooded 55
Pond 100
ONSITE IMPERVIOUS BREAKDOWN
Imp per Lot Imp Area
# of Lots [sf] [sf]
0.00 3,650 0
- - 47,330
Total Onsite Impervious Area =47,330 sf
WATERSHED BREAKDOWN
Composite Area Area
SCS CN [sf][acres]
98 0 0.00
61 0 0.00
55 0 0.00
100 0 0.00
98 0 0.00
61 7,440 0.17
55 0 0.00
100 0 0.00
Total Area =7,440 sf
=0.17 acres
Composite SCS CN =61
% Impervious =0.0%
TIME OF CONCENTRATION
(REF: SCS Segmental Approach, TR-55).
Segment 1: Overland Flow Segment 2: Concentrated Flow
Length =100 ft Length =114 ft
Upstream Elevation =859.00 ft Upstream Elevation =851.00 ft
Downstream Elevation =851.00 ft Downstream Elevation =838.00 ft
Height =8.00 ft Height =13.00 ft
Slope =0.0800 ft/ft Slope =0.1140 ft/ft
Manning's n =0.24 dense grasses Paved?No
P (2-year/24-hour) =3.38 inches (Troutman, NC) Velocity =5.45 ft/sec
Segment Time =7.97 minutes Segment Time =0.35 minutes
Segment 3: Channel Flow
Length =4237 ft
Offsite Pond -
Offsite Impervious -
Offsite Open Assume good condition
Offsite Wooded Assume good condition
Onsite Open Assume good condition
Onsite Wooded Assume good condition
Onsite Pond -
Onsite Impervious -
POST DEVELOPMENT HYDROLOGIC CALCULATIONS
Comments
-
Assume good condition
Assume good condition
-
Contributing Area
Lot Impervious
Measured Impervious
Contributing Area Comments
Project Name: Howard Property Date: 10/5/2018
Project Number:RYN-18000 Calculated By: K. Gallt
Subbasin ID:Reach Data
REACH DATA
(REF: SCS Segmental Approach, TR-55).
REACH 1: POA A to POA 1
Length =3254 ft
Upstream Elevation =834.00 ft
Downstream Elevation =804.00 ft
Height =30.00 ft
Slope =0.0092 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 =3.85 ft/sec
Segment Time =14.08 minutes
REACH 2: POA B to POA 1
Length =878 ft
Upstream Elevation =818.00 ft
Downstream Elevation =804.00 ft
Height =14.00 ft
Slope =0.0159 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 =5.07 ft/sec
Segment Time =2.89 minutes
POST DEVELOPMENT HYDROLOGIC CALCULATIONS
REACH 210/5/2018RYN18000.ppc
K. GALLTHOWARD
Subsection: Master Network Summary
Catchments Summary
Peak Flow
(ft³/s)
Time to Peak
(min)
Hydrograph
Volume
(ac-ft)
Return
Event
(years)
ScenarioLabel
94.65723.0005.4032Post 2 yearSUB 1 TO SCM A
186.38720.00011.40910Post 10 yearSUB 1 TO SCM A
241.22720.00015.45825Post 25 yearSUB 1 TO SCM A
320.10720.00022.409100Post 100 yearSUB 1 TO SCM A
34.82723.0001.9122Post 2 yearSUB 1 TO SCM B
62.98720.0003.74210Post 10 yearSUB 1 TO SCM B
78.38720.0004.93925Post 25 yearSUB 1 TO SCM B
99.87720.0006.956100Post 100 yearSUB 1 TO SCM B
7.17741.0001.0812Post 2 yearSUB 1 BYPASS
22.74738.0002.80410Post 10 yearSUB 1 BYPASS
32.94735.0004.05825Post 25 yearSUB 1 BYPASS
49.31735.0006.314100Post 100 yearSUB 1 BYPASS
Node Summary
Peak Flow
(ft³/s)
Time to Peak
(min)
Hydrograph
Volume
(ac-ft)
Return
Event
(years)
ScenarioLabel
19.62765.0005.7382Post 2 yearPOA 1
69.38744.00015.17410Post 10 yearPOA 1
98.82753.00021.59925Post 25 yearPOA 1
146.23738.00032.708100Post 100 yearPOA 1
10.74756.0003.4672Post 2 yearPOA 1A
31.83756.0009.39110Post 10 yearPOA 1A
53.72753.00013.39025Post 25 yearPOA 1A
68.97753.00020.263100Post 100 yearPOA 1A
7.88753.0001.2302Post 2 yearPOA 1B
27.97729.0003.05310Post 10 yearPOA 1B
44.91729.0004.24525Post 25 yearPOA 1B
72.49726.0006.256100Post 100 yearPOA 1B
Pond Summary
Maximum
Pond Storage
(ac-ft)
Maximum
Water
Surface
Elevation
(ft)
Peak Flow
(ft³/s)
Time to Peak
(min)
Hydrograph
Volume
(ac-ft)
Return
Event
(years)
ScenarioLabel
(N/A)(N/A)94.65723.0005.4032Post 2 yearSCM A (IN)
2.419834.0910.74756.0003.4672Post 2 yearSCM A
(OUT)
(N/A)(N/A)186.38720.00011.40910Post 10 yearSCM A (IN)
4.816835.5131.83756.0009.39110Post 10 yearSCM A
(OUT)
(N/A)(N/A)241.22720.00015.45825Post 25 yearSCM A (IN)
10/5/2018RYN18000.ppc
K. GALLTHOWARD
Subsection: Master Network Summary
Pond Summary
Maximum
Pond Storage
(ac-ft)
Maximum
Water
Surface
Elevation
(ft)
Peak Flow
(ft³/s)
Time to Peak
(min)
Hydrograph
Volume
(ac-ft)
Return
Event
(years)
ScenarioLabel
6.290836.3353.72753.00013.39025Post 25 yearSCM A
(OUT)
(N/A)(N/A)320.10720.00022.409100Post 100 yearSCM A (IN)
9.017837.7868.97753.00020.263100Post 100 yearSCM A
(OUT)
(N/A)(N/A)34.82723.0001.9122Post 2 yearSCM B (IN)
0.805827.047.88753.0001.2302Post 2 yearSCM B
(OUT)
(N/A)(N/A)62.98720.0003.74210Post 10 yearSCM B (IN)
1.187827.8527.97729.0003.05310Post 10 yearSCM B
(OUT)
(N/A)(N/A)78.38720.0004.93925Post 25 yearSCM B (IN)
1.407828.2944.91729.0004.24525Post 25 yearSCM B
(OUT)
(N/A)(N/A)99.87720.0006.956100Post 100 yearSCM B (IN)
1.595828.6672.49726.0006.256100Post 100 yearSCM B
(OUT)
10/5/2018RYN18000.ppc
K. GALLTHOWARD
N19° 4
6'

1
9
.
5
3
"
E
L=3
998.2
7
8'
R 0
9.'2=702.5 '
HOWARD
RYN-18000

DESIGN OF STORMWATER CONTROL
MEASURE A

Project Name:Howard Property Date:10/5/2018
Project Number:RYN-18000 Calculated By:J. Aldridge, P.E.
Facility ID:SCM 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]
832.50 0.00 60,213
833.50 1.00 68,783 64,498 64,498 64,498 1.01
834.00 1.50 70,591 69,687 34,844 99,342 1.50
836.00 3.50 77,963 74,277 148,554 247,896 3.46
838.00 5.50 85,561 81,762 163,524 411,420 5.50
839.00 6.50 89,445 87,503 87,503 498,923 6.56
b =1.0914
Ks =64035
STAGE-STORAGE FUNCTION - ABOVE NORMAL POOL
y = 64035x1.0914
R² = 0.9999
0
100,000
200,000
300,000
400,000
500,000
600,000
0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00Storage (CF)Stage (feet)
Storage vs. Stage
Project Name:Howard Property Date:10/5/2018
Project Number:RYN-18000 Calculated By:K. Gallt
Facility ID:SCM A
MAIN POOL
Average Incremental Accumulated Calculated
Contour Stage Contour Area Contour Area Contour Vol Contour Vol Stage
[ft][ft][sf][sf][cf][cf][ft]
828.00 0.00 30,272
830.00 2.00 35,096 32,684 65,368 65,368 2.00
832.00 4.00 40,174 37,635 75,270 140,638 3.99
832.50 4.50 41,473 40,824 20,412 161,050 4.51
b =1.1096
Ks =30281
STAGE-STORAGE FUNCTION - BELOW NORMAL POOL
y = 30281x1.1096
R² = 1
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 5.00Storage (CF)Stage (feet)
Storage vs. Stage
NORTH FOREBAY
Average Incremental Accumulated Calculated
Contour Stage Contour Area Contour Area Contour Vol Contour Vol Stage
[ft][ft][sf][sf][cf][cf][ft]
828.00 0.00 4,772
830.00 2.00 6,641 5,707 11,413 11,413 2.00
832.00 4.00 8,748 7,695 15,389 26,802 3.98
832.50 4.50 9,307 9,028 4,514 31,316 4.52
b =1.2402
Ks =4828
y = 4827.7x1.2402
R² = 0.9999
0
5,000
10,000
15,000
20,000
25,000
30,000
35,000
0.00 1.00 2.00 3.00 4.00 5.00Storage (CF)Stage (feet)
Storage vs. Stage
SOUTH FOREBAY
Average Incremental Accumulated Calculated
Contour Stage Contour Area Contour Area Contour Vol Contour Vol Stage
[ft][ft][sf][sf][cf][cf][ft]
828.00 0.00 4,642
830.00 2.00 6,644 5,643 11,286 11,286 2.00
832.00 4.00 8,908 7,776 15,552 26,838 3.98
832.50 4.50 9,502 9,205 4,603 31,441 4.52
b =1.2587
Ks =4713
y = 4713x1.2587
R² = 0.9999
0
5,000
10,000
15,000
20,000
25,000
30,000
35,000
0.00 1.00 2.00 3.00 4.00 5.00Storage (CF)Stage (feet)
Storage vs. Stage
Project Name:Howard Property Date:10/5/2018
Project Number:RYN-18000 Calculated By:J. Aldridge, P.E.
Facility ID:SCM A
TOTAL VOLUME
Volume of Main Pool =161,050 cf
Volume of North Forebay =31,316 cf
Volume of South Forebay =31,441 cf
Total Volume Below NWSE =223,806 cf
=5.14 acre-ft
Total Volume Above NWSE =498,923 cf
=11.45 acre-ft
Total Volume of Facility =722,729 cf
=16.59 acre-ft
FOREBAY CALCULATION
Volume of Main Pool =161,050 cf
Volume of Forebays =62,756 cf
% Forebay =39%Forebay volume should be approximately 20%
AVERAGE DEPTH OF MAIN POOL
Volume of Main Pool =161,050 cf
Surface Area of Main Pool =41,473 sf
Average Depth of Main Pool =3.88 Average depth must be greater than 3.0
VOLUME CALCULATIONS
Project Name:Howard Property Date:10/5/2018
Project Number:RYN-18000 Calculated By:J. Aldridge, P.E.
Facility ID:SCM A
DRAINAGE CHARACTERISTICS
Total Drainage Area =65.73 acres
Total Impervious Area =16.30 acres Include both onsite and offsite impervious area
% Impervious =24.8%
DETERMINATION OF REQUIRED SURFACE AREA
(REF: NCDEQ Stormwater BMP Manual, 2017)
Average Depth of Main Pool =3.88 ft
TSS Removal =85%
SA/DA table for Piedmont/Mountain region
3 3.88 4
20.0%0.84 0.69
24.8%1.00 0.83 0.81
30.0%1.17 0.94
SA/DA required =0.83
Main Pool SA Required =23,825 sf
=0.55 acres
Main Pool SA Provided =41,473 sf
SURFACE AREA CALCULATION
Lower Boundary
% Impervious
Upper Boundary
Average Depth
Project Name:Howard Property Date:10/5/2018
Project Number:RYN-18000 Calculated By:J. Aldridge, P.E.
Facility ID:SCM A
DETERMINATION OF 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 =65.73 acres
Total Impervious Area =16.30 acres
% Impervious, I =24.8%
Rainfall, P =1.00 inches
Rv =0.273 acres
WQV =1.497 acre-ft
65,196 cf
ASSOCIATED DEPTH IN POND
WQV =65,196 cf
Ks =64035
b =1.0914
NWSE =832.50 ft
Depth of WQV in Pond =1.02 ft
=12.20 inches
Elevation =833.52 ft Spillway must be set above this elevation
WATER QUALITY VOLUME CALCULATION
Project Name:Howard Property Date:10/5/2018
Project Number:RYN-18000 Calculated By:J. Aldridge, P.E.
Facility ID:SCM A
DRAWDOWN DESIGN
Using falling head
Orifice Diameter =5.00 inches
Number of Orifices =1
Orifice Coefficient, Cd =0.60
Ks =64035
b =1.0914
NWSE =832.50 ft
WQV =65,196
WQV Elevation in Pond =833.52 ft
Average Incremental Incremental
WSEL Storage Siphon Flow Flow Volume Time
[ft][cf][cfs][cfs][cf][sec]
833.52 65196 0.589
833.43 58969 0.556 0.573 6,227 10,875
833.34 52797 0.520 0.538 6,172 11,473
833.25 46685 0.482 0.501 6,112 12,201
833.16 40639 0.440 0.461 6,046 13,114
833.07 34668 0.394 0.417 5,971 14,313
832.98 28782 0.342 0.368 5,886 15,990
832.89 22996 0.273 0.308 5,786 18,812
832.80 17331 0.185 0.229 5,666 24,725
832.71 11818 0.109 0.147 5,512 37,428
832.62 6520 0.048 0.079 5,299 67,197
Drawdown Time =2.62 days 2-5 day drawdown required
DRAWDOWN DESIGN
Using average head
Average Head on Orifice =0.269 inches
Orifice Coefficient, Cd =0.60
Area of Orifice =0.136 sf
Flowrate, Q =0.341 cfs
Drawdown Time =2.21 days 2-5 day drawdown required
WATER QUALITY VOLUME DRAWDOWN CALCULATION
Project Name:Howard Property Date:10/5/2018
Project Number:RYN-18000 Calculated By:K. Gallt
Facility ID:SCM A
INPUT DATA
Inside Length =5.00 ft
Inside Width =5.00 ft
Wall Thickness =6.00 in
Standard Base Length =6.00 ft
Standard Base Width =6.00 ft
Standard Base Thickness =6.00 in
Inside Height of Riser =3.50 ft
Concrete Unit Weight =142.00 pcf Unit weight of manhole concrete is 142 pcf per NC Products
Outside Diameter of Barrel =44.00 in
Drain Pipe (if present) =8.00 in
TRASH RACK DISPLACEMENT
Bottom Length / Width =8.40 ft Calculation for truncated square pyramid
Top Length / Width =2.10 ft
Height =2.00 ft
Trash Rack Displacement =61.740 cf
CONCRETE PRESENT IN RISER STRUCTURE
Riser Walls =38.500 cf
Standard Base of Riser =18.000 cf
Less Opening for Barrel =5.280 cf
Less Opening for Drain Pipe =0.175 cf
Total Concrete Less Openings =51.046 cf
Weight of Concrete =7,249 lbs
AMOUNT OF WATER DISPLACED BY RISER STRUCTURE
Displacement by Concrete =51.046 cf
Displacement by Open Air =87.500 cf
Displacement by Trash Rack =61.740 cf
Total Water Displaced =200.286 cf
Weight of Water Displaced =12,498 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 =7,124 lbs
Bouyant Weight of Concrete =79.60 pcf
Bouyant Weight w/ SF =69.22 pcf
Add'l Concrete to Add =102.922 cf
Less Standard Base =18.000 cf
New Base Design Required =120.922 cf
ANTI FLOTATION BLOCK DESIGN CALCULATIONS
AF Block Length =8.00 ft
AF Block Width =8.00 ft
AF Block Thickness =24.00 in
AF Block Provided =128.000 cf
Total Concrete Present =161.046 cf
Total Concrete Present =22,869 lbs
Project Name: Howard Date: 10/5/2018
Project Number: RYN-18000 Calculated By: K. Gallt
Facility ID: SCM 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 =31.83 cfs
Slope =1.04 %
Pipe Diameter, Do =36 in
=3.00 feet
Number of pipes =1
Pipe separation =0.00 feet
Manning's n =0.013
Zone from graph above =2
Outlet pipe diameter =36 in Length =18.00 ft
Outlet flowrate =31.83 cfs Width =9.00 ft
Outlet velocity =9.48 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
9.48 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: 2 yearLabel: SCM A
Return Event: 2 yearsSubsection: Elevation-Area Volume Curve
Volume (Total)
(ac-ft)
Volume
(ac-ft)
A1+A2+sqr
(A1*A2)
(ft²)
Area
(ft²)
Planimeter
(ft²)
Elevation
(ft)
0.0000.0000.0060,213.000.00832.50
1.4801.480193,351.5068,783.000.00833.50
2.2790.800209,055.1470,591.000.00834.00
5.6883.409222,739.4877,963.000.00836.00
9.4413.753245,197.6985,561.000.00838.00
11.4502.009262,487.4589,445.000.00839.00
10/5/2018RYN18000.ppc
K. GALLTHOWARD
Storm Event: 2 yearLabel: SCM A
Return Event: 2 yearsSubsection: Outlet Input Data
Requested Pond Water Surface Elevations
ft832.50Minimum (Headwater)
ft0.10Increment (Headwater)
ft839.00Maximum (Headwater)
Outlet Connectivity
E2
(ft)
E1
(ft)
OutfallDirectionOutlet IDStructure Type
839.00833.75CulvertForwardOrificeOrifice-Area
839.00835.50CulvertForwardRiserInlet Box
839.00832.50CulvertForwardSiphonOrifice-Circular
839.00832.00TWForwardCulvertCulvert-Circular
(N/A)(N/A)TailwaterTailwater Settings
10/5/2018RYN18000.ppc
K. GALLTHOWARD
Storm Event: 2 yearLabel: SCM A
Return Event: 2 yearsSubsection: Outlet Input Data
Structure ID: Culvert
Structure Type: Culvert-Circular
1Number of Barrels
in36.00Diameter
ft48.00Length
ft48.00Length (Computed Barrel)
ft/ft0.010Slope (Computed)
Outlet Control Data
0.013Manning's n
0.500Ke
0.007Kb
0.000Kr
ft0.00Convergence Tolerance
Inlet Control Data
Form 1Equation Form
0.0098K
2.0000M
0.0398C
0.6700Y
0.000T1 ratio (HW/D)
1.302T2 ratio (HW/D)
-0.500Slope 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...
ft832.00T1 Elevation ft³/s42.85T1 Flow
ft835.90T2 Elevation ft³/s48.97T2 Flow
10/5/2018RYN18000.ppc
K. GALLTHOWARD
Storm Event: 2 yearLabel: SCM A
Return Event: 2 yearsSubsection: Outlet Input Data
Structure ID: Riser
Structure Type: Inlet Box
1Number of Openings
ft835.50Elevation
ft²25.00Orifice Area
0.600Orifice Coefficient
ft20.00Weir Length
(ft^0.5)/s3.00Weir Coefficient
1.000K Reverse
0.000Manning's n
0.000Kev, Charged Riser
FalseWeir Submergence
FalseOrifice H to crest
Structure ID: Siphon
Structure Type: Orifice-Circular
1Number of Openings
ft832.50Elevation
in5.00Orifice Diameter
0.600Orifice Coefficient
Structure ID: Orifice
Structure Type: Orifice-Area
3Number of Openings
ft833.75Elevation
ft²3.00Orifice Area
ft834.75Top Elevation
ft834.25Datum Elevation
0.600Orifice 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)
10/5/2018RYN18000.ppc
K. GALLTHOWARD
Storm Event: 2 yearLabel: SCM A
Return Event: 2 yearsSubsection: Outlet Input Data
Convergence Tolerances
ft³/s0.001Flow Tolerance (Minimum)
ft³/s10.000Flow Tolerance (Maximum)
10/5/2018RYN18000.ppc
K. GALLTHOWARD
Storm Event: 2 yearLabel: SCM A
Return Event: 2 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)0.00832.50
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.02832.60
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.08832.70
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.17832.80
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.27832.90
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.35833.00
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.41833.10
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.46833.20
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.50833.30
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.55833.40
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.58833.50
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.62833.60
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.65833.70
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.67833.75
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)2.22833.80
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)5.18833.90
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)8.17834.00
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)11.16834.10
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)13.25834.20
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)14.67834.30
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)16.28834.40
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)18.21834.50
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)20.25834.60
10/5/2018RYN18000.ppc
K. GALLTHOWARD
Storm Event: 2 yearLabel: SCM A
Return Event: 2 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)22.11834.70
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)23.76834.80
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)24.91834.90
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)26.06835.00
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)27.20835.10
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)28.35835.20
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)29.46835.30
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)30.59835.40
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)31.71835.50
Orifice,Riser,Siphon,Culver
t
0.00(N/A)33.49835.60
Orifice,Riser,Siphon,Culver
t
0.00(N/A)35.87835.70
Orifice,Riser,Siphon,Culver
t
0.00(N/A)38.58835.80
Orifice,Riser,Siphon,Culver
t
0.00(N/A)41.55835.90
Orifice,Riser,Siphon,Culver
t
0.00(N/A)44.64836.00
Orifice,Riser,Siphon,Culver
t
0.00(N/A)47.79836.10
Orifice,Riser,Siphon,Culver
t
0.00(N/A)50.84836.20
Orifice,Riser,Siphon,Culver
t
0.00(N/A)53.17836.30
Orifice,Riser,Siphon,Culver
t
0.00(N/A)54.82836.40
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)56.08836.50
10/5/2018RYN18000.ppc
K. GALLTHOWARD
Storm Event: 2 yearLabel: SCM A
Return Event: 2 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)57.20836.60
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)58.28836.70
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)59.34836.80
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)60.39836.90
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)61.43837.00
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)62.44837.10
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)63.44837.20
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)64.42837.30
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)65.39837.40
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)66.34837.50
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)67.28837.60
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)68.21837.70
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)69.12837.80
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)70.02837.90
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)70.91838.00
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)71.79838.10
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)72.67838.20
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)73.53838.30
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)74.36838.40
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)75.21838.50
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)76.03838.60
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)76.87838.70
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)77.68838.80
10/5/2018RYN18000.ppc
K. GALLTHOWARD
Storm Event: 2 yearLabel: SCM A
Return Event: 2 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)78.48838.90
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)79.27839.00
10/5/2018RYN18000.ppc
K. GALLTHOWARD
Storm Event: 2 yearLabel: SCM A (IN)
Return Event: 2 yearsSubsection: Level Pool Pond Routing Summary
Infiltration
No InfiltrationInfiltration Method
(Computed)
Initial Conditions
ft832.50Elevation (Water Surface,
Initial)
ac-ft0.000Volume (Initial)
ft³/s0.00Flow (Initial Outlet)
ft³/s0.00Flow (Initial Infiltration)
ft³/s0.00Flow (Initial, Total)
min3.000Time Increment
Inflow/Outflow Hydrograph Summary
ft³/s94.65Flow (Peak In) min723.000Time to Peak (Flow, In)
ft³/s10.74Flow (Peak Outlet) min756.000Time to Peak (Flow, Outlet)
ft834.09Elevation (Water Surface,
Peak)
ac-ft2.419Volume (Peak)
Mass Balance (ac-ft)
ac-ft0.000Volume (Initial)
ac-ft5.403Volume (Total Inflow)
ac-ft0.000Volume (Total Infiltration)
ac-ft3.467Volume (Total Outlet
Outflow)
ac-ft1.928Volume (Retained)
ac-ft-0.007Volume (Unrouted)
%0.1Error (Mass Balance)
10/5/2018RYN18000.ppc
K. GALLTHOWARD
Storm Event: 10 yearLabel: SCM A (IN)
Return Event: 10 yearsSubsection: Level Pool Pond Routing Summary
Infiltration
No InfiltrationInfiltration Method
(Computed)
Initial Conditions
ft832.50Elevation (Water Surface,
Initial)
ac-ft0.000Volume (Initial)
ft³/s0.00Flow (Initial Outlet)
ft³/s0.00Flow (Initial Infiltration)
ft³/s0.00Flow (Initial, Total)
min3.000Time Increment
Inflow/Outflow Hydrograph Summary
ft³/s186.38Flow (Peak In) min720.000Time to Peak (Flow, In)
ft³/s31.83Flow (Peak Outlet) min756.000Time to Peak (Flow, Outlet)
ft835.51Elevation (Water Surface,
Peak)
ac-ft4.816Volume (Peak)
Mass Balance (ac-ft)
ac-ft0.000Volume (Initial)
ac-ft11.409Volume (Total Inflow)
ac-ft0.000Volume (Total Infiltration)
ac-ft9.391Volume (Total Outlet
Outflow)
ac-ft2.005Volume (Retained)
ac-ft-0.013Volume (Unrouted)
%0.1Error (Mass Balance)
10/5/2018RYN18000.ppc
K. GALLTHOWARD
Storm Event: 25 yearLabel: SCM A (IN)
Return Event: 25 yearsSubsection: Level Pool Pond Routing Summary
Infiltration
No InfiltrationInfiltration Method
(Computed)
Initial Conditions
ft832.50Elevation (Water Surface,
Initial)
ac-ft0.000Volume (Initial)
ft³/s0.00Flow (Initial Outlet)
ft³/s0.00Flow (Initial Infiltration)
ft³/s0.00Flow (Initial, Total)
min3.000Time Increment
Inflow/Outflow Hydrograph Summary
ft³/s241.22Flow (Peak In) min720.000Time to Peak (Flow, In)
ft³/s53.72Flow (Peak Outlet) min753.000Time to Peak (Flow, Outlet)
ft836.33Elevation (Water Surface,
Peak)
ac-ft6.290Volume (Peak)
Mass Balance (ac-ft)
ac-ft0.000Volume (Initial)
ac-ft15.458Volume (Total Inflow)
ac-ft0.000Volume (Total Infiltration)
ac-ft13.390Volume (Total Outlet
Outflow)
ac-ft2.051Volume (Retained)
ac-ft-0.017Volume (Unrouted)
%0.1Error (Mass Balance)
10/5/2018RYN18000.ppc
K. GALLTHOWARD
Storm Event: 100 yearLabel: SCM A (IN)
Return Event: 100 yearsSubsection: Level Pool Pond Routing Summary
Infiltration
No InfiltrationInfiltration Method
(Computed)
Initial Conditions
ft832.50Elevation (Water Surface,
Initial)
ac-ft0.000Volume (Initial)
ft³/s0.00Flow (Initial Outlet)
ft³/s0.00Flow (Initial Infiltration)
ft³/s0.00Flow (Initial, Total)
min3.000Time Increment
Inflow/Outflow Hydrograph Summary
ft³/s320.10Flow (Peak In) min720.000Time to Peak (Flow, In)
ft³/s68.97Flow (Peak Outlet) min753.000Time to Peak (Flow, Outlet)
ft837.78Elevation (Water Surface,
Peak)
ac-ft9.018Volume (Peak)
Mass Balance (ac-ft)
ac-ft0.000Volume (Initial)
ac-ft22.409Volume (Total Inflow)
ac-ft0.000Volume (Total Infiltration)
ac-ft20.263Volume (Total Outlet
Outflow)
ac-ft2.124Volume (Retained)
ac-ft-0.023Volume (Unrouted)
%0.1Error (Mass Balance)
10/5/2018RYN18000.ppc
K. GALLTHOWARD
HOWARD
RYN-18000

DESIGN OF STORMWATER CONTROL
MEASURE B

Project Name:Howard Property Date:10/5/2018
Project Number:RYN-18000 Calculated By:J. Aldridge, PE
Facility ID:SCM 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]
825.00 0.00 13,667
826.00 1.00 17,716 15,692 15,692 15,692 1.00
828.00 3.00 21,580 19,648 39,296 54,988 2.96
830.00 5.00 25,671 23,626 47,251 102,239 5.05
b =1.1608
Ks =15611
STAGE-STORAGE FUNCTION - ABOVE NORMAL POOL
y = 15611x1.1608
R² = 0.9998
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:Howard Property Date:10/5/2018
Project Number:RYN-18000 Calculated By:J. Aldridge, PE
Facility ID:SCM 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]
818.00 0.00 4,085
820.00 2.00 5,697 4,891 9,782 9,782 2.02
822.00 4.00 7,443 6,570 13,140 22,922 3.91
824.00 6.00 9,317 8,380 16,760 39,682 5.99
825.00 7.00 10,288 9,803 9,803 49,485 7.10
b =1.2897
Ks =3948
STAGE-STORAGE FUNCTION - BELOW NORMAL POOL
y = 3948.2x1.2897
R² = 0.9991
0
10,000
20,000
30,000
40,000
50,000
60,000
0.00 2.00 4.00 6.00 8.00Storage (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]
818.00 0.00 883
820.00 2.00 1,443 1,163 2,326 2,326 2.03
822.00 4.00 2,127 1,785 3,570 5,896 3.88
824.00 6.00 2,939 2,533 5,066 10,962 5.98
825.00 7.00 3,379 3,159 3,159 14,121 7.14
b =1.4333
Ks =844
y = 844.29x1.4333
R² = 0.9984
0
2,000
4,000
6,000
8,000
10,000
12,000
14,000
16,000
0.00 2.00 4.00 6.00 8.00Storage (CF)Stage (feet)
Storage vs. Stage
Project Name:Howard Property Date:10/5/2018
Project Number:RYN-18000 Calculated By:J. Aldridge, PE
Facility ID:SCM B
TOTAL VOLUME
Volume of Main Pool =49,485 cf
Volume of Forebay =14,121 cf
Total Volume Below NWSE =63,606 cf
=1.46 acre-ft
Total Volume Above NWSE =102,239 cf
=2.35 acre-ft
Total Volume of Facility =165,844 cf
=3.81 acre-ft
FOREBAY CALCULATION
Total Volume Below NWSE =63,606 cf
Volume of Forebays =14,121 cf
% Forebay =22%Forebay volume should be approximately 20%
AVERAGE DEPTH OF MAIN POOL
Volume of Main Pool =49,485 cf
Surface Area of Main Pool =10,288 sf
Average Depth of Main Pool =4.81 Average depth must be greater than 3.0
VOLUME CALCULATIONS
Project Name:Howard Property Date:10/5/2018
Project Number:RYN-18000 Calculated By:J. Aldridge, PE
Facility ID:SCM B
DRAINAGE CHARACTERISTICS
Total Drainage Area =17.97 acres
Total Impervious Area =7.08 acres Include both onsite and offsite impervious area
% Impervious =39.4%
DETERMINATION OF REQUIRED SURFACE AREA
(REF: NCDEQ Stormwater BMP Manual, 2017)
Average Depth of Main Pool =4.81 ft
TSS Removal =85%
SA/DA table for Piedmont/Mountain region
4 4.81 5
30.0%0.94 0.84
39.4%1.22 1.10 1.07
40.0%1.24 1.09
SA/DA required =1.10
Main Pool SA Required =8,629 sf
=0.20 acres
Main Pool SA Provided =10,288 sf
SURFACE AREA CALCULATION
Lower Boundary
% Impervious
Upper Boundary
Average Depth
Project Name:Howard Property Date:10/5/2018
Project Number:RYN-18000 Calculated By:J. Aldridge, PE
Facility ID:SCM B
DETERMINATION OF 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 =17.97 acres
Total Impervious Area =7.08 acres
% Impervious, I =39.4%
Rainfall, P =1.00 inches
Rv =0.404 acres
WQV =0.606 acre-ft
26,380 cf
ASSOCIATED DEPTH IN POND
WQV =26,380 cf
Ks =15611
b =1.1608
NWSE =825.00 ft
Depth of WQV in Pond =1.57 ft
=18.86 inches
Elevation =826.57 ft Spillway must be set above this elevation
WATER QUALITY VOLUME CALCULATION
Project Name:Howard Property Date:10/5/2018
Project Number:RYN-18000 Calculated By:J. Aldridge, PE
Facility ID:SCM B
DRAWDOWN DESIGN
Using falling head
Orifice Diameter =2.50 inches
Number of Orifices =1
Orifice Coefficient, Cd =0.60
Ks =15611
b =1.1608
NWSE =825.00 ft
WQV =26,380
WQV Elevation in Pond =826.57 ft
Average Incremental Incremental
WSEL Storage Siphon Flow Flow Volume Time
[ft][cf][cfs][cfs][cf][sec]
826.57 26380 0.198
826.44 23757 0.189 0.194 2,622 13,530
826.30 21175 0.179 0.184 2,583 14,023
826.16 18635 0.169 0.174 2,540 14,596
826.03 16143 0.158 0.163 2,492 15,273
825.89 13703 0.146 0.152 2,440 16,093
825.76 11322 0.133 0.139 2,381 17,121
825.62 9008 0.118 0.125 2,313 18,466
825.49 6775 0.101 0.110 2,233 20,354
825.35 4641 0.082 0.091 2,134 23,331
825.22 2638 0.055 0.068 2,003 29,375
Drawdown Time =2.11 days 2-5 day drawdown required
DRAWDOWN DESIGN
Using average head
Average Head on Orifice =0.489 inches
Orifice Coefficient, Cd =0.60
Area of Orifice =0.034 sf
Flowrate, Q =0.115 cfs
Drawdown Time =2.66 days 2-5 day drawdown required
WATER QUALITY VOLUME DRAWDOWN CALCULATION
Project Name:Howard Property Date:10/5/2018
Project Number:RYN-18000 Calculated By:K. Gallt
Facility ID:SCM B
INPUT DATA
Inside Length =5.00 ft
Inside Width =5.00 ft
Wall Thickness =6.00 in
Standard Base Length =6.00 ft
Standard Base Width =6.00 ft
Standard Base Thickness =6.00 in
Inside Height of Riser =10.25 ft
Concrete Unit Weight =142.00 pcf Unit weight of manhole concrete is 142 pcf per NC Products
Outside Diameter of Barrel =44.00 in
Drain Pipe (if present) =8.00 in
TRASH RACK DISPLACEMENT
Bottom Length / Width =8.40 ft Calculation for truncated square pyramid
Top Length / Width =2.10 ft
Height =2.00 ft
Trash Rack Displacement =61.740 cf
CONCRETE PRESENT IN RISER STRUCTURE
Riser Walls =112.750 cf
Standard Base of Riser =18.000 cf
Less Opening for Barrel =5.280 cf
Less Opening for Drain Pipe =0.175 cf
Less Opening for Orifice =4.500 cf
Total Concrete Less Openings =120.796 cf
Weight of Concrete =17,153 lbs
AMOUNT OF WATER DISPLACED BY RISER STRUCTURE
Displacement by Concrete =120.796 cf
Displacement by Open Air =256.250 cf
Displacement by Trash Rack =61.740 cf
Total Water Displaced =438.786 cf
Weight of Water Displaced =27,380 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 =14,334 lbs
Bouyant Weight of Concrete =79.60 pcf
Bouyant Weight w/ SF =69.22 pcf
Add'l Concrete to Add =207.090 cf
Less Standard Base =18.000 cf
New Base Design Required =225.090 cf
ANTI FLOTATION BLOCK DESIGN CALCULATIONS
AF Block Length =8.00 ft
AF Block Width =8.00 ft
AF Block Thickness =44.00 in
AF Block Provided =234.667 cf
Total Concrete Present =341.963 cf
Total Concrete Present =48,559 lbs
Project Name: Howard Date: 10/5/2018
Project Number: RYN-18000 Calculated By: K. Gallt
Facility ID: SCM 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 =27.97 cfs
Slope =1.12 %
Pipe Diameter, Do =36 in
=3.00 feet
Number of pipes =1
Pipe separation =0.00 feet
Manning's n =0.013
Zone from graph above =2
Outlet pipe diameter =36 in Length =18.00 ft
Outlet flowrate =27.97 cfs Width =9.00 ft
Outlet velocity =9.42 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
9.42 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: 2 yearLabel: SCM B
Return Event: 2 yearsSubsection: Elevation-Area Volume Curve
Volume (Total)
(ac-ft)
Volume
(ac-ft)
A1+A2+sqr
(A1*A2)
(ft²)
Area
(ft²)
Planimeter
(ft²)
Elevation
(ft)
0.0000.0000.0013,667.000.00825.00
0.3590.35946,943.3517,716.000.00826.00
1.2600.90158,848.7821,580.000.00828.00
2.3431.08370,787.7825,671.000.00830.00
10/5/2018RYN18000.ppc
K. GALLTHOWARD
Storm Event: 2 yearLabel: SCM B
Return Event: 2 yearsSubsection: Outlet Input Data
Requested Pond Water Surface Elevations
ft825.00Minimum (Headwater)
ft0.10Increment (Headwater)
ft830.00Maximum (Headwater)
Outlet Connectivity
E2
(ft)
E1
(ft)
OutfallDirectionOutlet IDStructure Type
830.00826.75CulvertForwardOrificeOrifice-Area
830.00828.00CulvertForwardRiserInlet Box
830.00825.00CulvertForwardSiphonOrifice-Circular
830.00817.75TWForwardCulvertCulvert-Circular
(N/A)(N/A)TailwaterTailwater Settings
10/5/2018RYN18000.ppc
K. GALLTHOWARD
Storm Event: 2 yearLabel: SCM B
Return Event: 2 yearsSubsection: Outlet Input Data
Structure ID: Culvert
Structure Type: Culvert-Circular
1Number of Barrels
in36.00Diameter
ft67.00Length
ft67.00Length (Computed Barrel)
ft/ft0.011Slope (Computed)
Outlet Control Data
0.013Manning's n
0.500Ke
0.007Kb
0.000Kr
ft0.00Convergence Tolerance
Inlet Control Data
Form 1Equation Form
0.0098K
2.0000M
0.0398C
0.6700Y
1.155T1 ratio (HW/D)
1.301T2 ratio (HW/D)
-0.500Slope 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...
ft821.21T1 Elevation ft³/s42.85T1 Flow
ft821.65T2 Elevation ft³/s48.97T2 Flow
10/5/2018RYN18000.ppc
K. GALLTHOWARD
Storm Event: 2 yearLabel: SCM B
Return Event: 2 yearsSubsection: Outlet Input Data
Structure ID: Riser
Structure Type: Inlet Box
1Number of Openings
ft828.00Elevation
ft²25.00Orifice Area
0.600Orifice Coefficient
ft20.00Weir Length
(ft^0.5)/s3.00Weir Coefficient
1.000K Reverse
0.000Manning's n
0.000Kev, Charged Riser
FalseWeir Submergence
FalseOrifice H to crest
Structure ID: Siphon
Structure Type: Orifice-Circular
1Number of Openings
ft825.00Elevation
in2.50Orifice Diameter
0.600Orifice Coefficient
Structure ID: Orifice
Structure Type: Orifice-Area
3Number of Openings
ft826.75Elevation
ft²2.25Orifice Area
ft827.50Top Elevation
ft827.13Datum Elevation
0.600Orifice 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)
10/5/2018RYN18000.ppc
K. GALLTHOWARD
Storm Event: 2 yearLabel: SCM B
Return Event: 2 yearsSubsection: Outlet Input Data
Convergence Tolerances
ft³/s0.001Flow Tolerance (Minimum)
ft³/s10.000Flow Tolerance (Maximum)
10/5/2018RYN18000.ppc
K. GALLTHOWARD
Storm Event: 2 yearLabel: SCM B
Return Event: 2 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)0.00825.00
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.01825.10
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.05825.20
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.07825.30
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.09825.40
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.10825.50
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.11825.60
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.13825.70
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.14825.80
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.14825.90
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.15826.00
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.16826.10
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.17826.20
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.18826.30
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.19826.40
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.19826.50
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.20826.60
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.21826.70
Siphon,Culvert (no Q:
Orifice,Riser)
0.00(N/A)0.21826.75
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)1.54826.80
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)4.20826.90
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)6.86827.00
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)9.52827.10
10/5/2018RYN18000.ppc
K. GALLTHOWARD
Storm Event: 2 yearLabel: SCM B
Return Event: 2 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)12.17827.20
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)14.83827.30
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)17.49827.40
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)20.15827.50
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)22.65827.60
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)24.91827.70
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)26.95827.80
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)28.88827.90
Orifice,Siphon,Culvert
(no Q: Riser)
0.00(N/A)30.68828.00
Orifice,Riser,Siphon,Culver
t
0.00(N/A)34.25828.10
Orifice,Riser,Siphon,Culver
t
0.00(N/A)39.33828.20
Orifice,Riser,Siphon,Culver
t
0.00(N/A)45.38828.30
Orifice,Riser,Siphon,Culver
t
0.00(N/A)52.17828.40
Orifice,Riser,Siphon,Culver
t
0.00(N/A)59.60828.50
Orifice,Riser,Siphon,Culver
t
0.00(N/A)67.62828.60
Orifice,Riser,Siphon,Culver
t
0.00(N/A)76.17828.70
Orifice,Riser,Siphon,Culver
t
0.00(N/A)85.22828.80
Orifice,Riser,Siphon,Culver
t
0.00(N/A)94.74828.90
Orifice,Riser,Siphon,Culver
t
0.00(N/A)99.11829.00
10/5/2018RYN18000.ppc
K. GALLTHOWARD
Storm Event: 2 yearLabel: SCM B
Return Event: 2 yearsSubsection: Composite Rating Curve
Composite Outflow Summary
Contributing StructuresConvergence Error
(ft)
Tailwater Elevation
(ft)
Flow
(ft³/s)
Water Surface
Elevation
(ft)
Orifice,Riser,Siphon,Culver
t
0.00(N/A)102.26829.10
Orifice,Riser,Siphon,Culver
t
0.00(N/A)105.13829.20
Orifice,Riser,Siphon,Culver
t
0.00(N/A)107.61829.30
Orifice,Riser,Siphon,Culver
t
0.00(N/A)109.50829.40
Orifice,Riser,Siphon,Culver
t
0.00(N/A)110.67829.50
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)111.23829.60
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)111.81829.70
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)112.37829.80
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)112.92829.90
Riser,Culvert (no Q:
Orifice,Siphon)
0.00(N/A)113.48830.00
10/5/2018RYN18000.ppc
K. GALLTHOWARD
Storm Event: 2 yearLabel: SCM B (IN)
Return Event: 2 yearsSubsection: Level Pool Pond Routing Summary
Infiltration
No InfiltrationInfiltration Method
(Computed)
Initial Conditions
ft825.00Elevation (Water Surface,
Initial)
ac-ft0.000Volume (Initial)
ft³/s0.00Flow (Initial Outlet)
ft³/s0.00Flow (Initial Infiltration)
ft³/s0.00Flow (Initial, Total)
min3.000Time Increment
Inflow/Outflow Hydrograph Summary
ft³/s34.82Flow (Peak In) min723.000Time to Peak (Flow, In)
ft³/s7.88Flow (Peak Outlet) min753.000Time to Peak (Flow, Outlet)
ft827.04Elevation (Water Surface,
Peak)
ac-ft0.805Volume (Peak)
Mass Balance (ac-ft)
ac-ft0.000Volume (Initial)
ac-ft1.912Volume (Total Inflow)
ac-ft0.000Volume (Total Infiltration)
ac-ft1.230Volume (Total Outlet
Outflow)
ac-ft0.680Volume (Retained)
ac-ft-0.002Volume (Unrouted)
%0.1Error (Mass Balance)
10/5/2018RYN18000.ppc
K. GALLTHOWARD
Storm Event: 10 yearLabel: SCM B (IN)
Return Event: 10 yearsSubsection: Level Pool Pond Routing Summary
Infiltration
No InfiltrationInfiltration Method
(Computed)
Initial Conditions
ft825.00Elevation (Water Surface,
Initial)
ac-ft0.000Volume (Initial)
ft³/s0.00Flow (Initial Outlet)
ft³/s0.00Flow (Initial Infiltration)
ft³/s0.00Flow (Initial, Total)
min3.000Time Increment
Inflow/Outflow Hydrograph Summary
ft³/s62.98Flow (Peak In) min720.000Time to Peak (Flow, In)
ft³/s27.97Flow (Peak Outlet) min729.000Time to Peak (Flow, Outlet)
ft827.85Elevation (Water Surface,
Peak)
ac-ft1.187Volume (Peak)
Mass Balance (ac-ft)
ac-ft0.000Volume (Initial)
ac-ft3.742Volume (Total Inflow)
ac-ft0.000Volume (Total Infiltration)
ac-ft3.053Volume (Total Outlet
Outflow)
ac-ft0.686Volume (Retained)
ac-ft-0.004Volume (Unrouted)
%0.1Error (Mass Balance)
10/5/2018RYN18000.ppc
K. GALLTHOWARD
Storm Event: 25 yearLabel: SCM B (IN)
Return Event: 25 yearsSubsection: Level Pool Pond Routing Summary
Infiltration
No InfiltrationInfiltration Method
(Computed)
Initial Conditions
ft825.00Elevation (Water Surface,
Initial)
ac-ft0.000Volume (Initial)
ft³/s0.00Flow (Initial Outlet)
ft³/s0.00Flow (Initial Infiltration)
ft³/s0.00Flow (Initial, Total)
min3.000Time Increment
Inflow/Outflow Hydrograph Summary
ft³/s78.38Flow (Peak In) min720.000Time to Peak (Flow, In)
ft³/s44.91Flow (Peak Outlet) min729.000Time to Peak (Flow, Outlet)
ft828.29Elevation (Water Surface,
Peak)
ac-ft1.407Volume (Peak)
Mass Balance (ac-ft)
ac-ft0.000Volume (Initial)
ac-ft4.939Volume (Total Inflow)
ac-ft0.000Volume (Total Infiltration)
ac-ft4.245Volume (Total Outlet
Outflow)
ac-ft0.689Volume (Retained)
ac-ft-0.005Volume (Unrouted)
%0.1Error (Mass Balance)
10/5/2018RYN18000.ppc
K. GALLTHOWARD
Storm Event: 100 yearLabel: SCM B (IN)
Return Event: 100 yearsSubsection: Level Pool Pond Routing Summary
Infiltration
No InfiltrationInfiltration Method
(Computed)
Initial Conditions
ft825.00Elevation (Water Surface,
Initial)
ac-ft0.000Volume (Initial)
ft³/s0.00Flow (Initial Outlet)
ft³/s0.00Flow (Initial Infiltration)
ft³/s0.00Flow (Initial, Total)
min3.000Time Increment
Inflow/Outflow Hydrograph Summary
ft³/s99.87Flow (Peak In) min720.000Time to Peak (Flow, In)
ft³/s72.49Flow (Peak Outlet) min726.000Time to Peak (Flow, Outlet)
ft828.66Elevation (Water Surface,
Peak)
ac-ft1.595Volume (Peak)
Mass Balance (ac-ft)
ac-ft0.000Volume (Initial)
ac-ft6.956Volume (Total Inflow)
ac-ft0.000Volume (Total Infiltration)
ac-ft6.256Volume (Total Outlet
Outflow)
ac-ft0.694Volume (Retained)
ac-ft-0.006Volume (Unrouted)
%0.1Error (Mass Balance)
10/5/2018RYN18000.ppc
K. GALLTHOWARD
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