SW1180402_Calcs_20190307

1.00
1.39
1.88
2.22
2.66
3.79
4.48
5.03
5.58
Highlighted Storm is Design Storm
32.50 acres 1.11 acres
0.00 acres 60%
0.00 acres
Complete the breakdown of impervious area for the project
No
2-yr, 24-hr
Storm Event
10-yr, 24-hr
25-yr, 24-hr(Minimum Design Storm = P90 for non-SA, 1-yr, 24-hr for SA)
Loaded Rainfall:
0
0
Entire Site
Total Impervious Area
Project % impervious area
ALL AREAS ARE IN SQUARE FEET
100-yr, 24-hr
PROJECT INFORMATION
RAINFALL & CALCULATION DATA
Rainfall Source:
Project County:
Project City:
MADISON
Mars Hill
Asheville
Design Storm:
Asheville
1-yr, 24-hr
Jo Ellen Ammons Fieldhouse for Mars Hill University
Mars Hill, NC MADISON County
French Broad River Basin
Depth
(inches)
First Flush / WQV
First Flush / WQV
P90
P95
50-yr, 24-hr
Total Property Area
Total Coastal Wetlands Area
Total Surface Water Area
Gabriel Creek
C
Use Worksheet Data?
Total Drainage Area
On-Site Drainage Area (sf)
6-96-12
81,116
81,116
Proposed Impervious Area (sf)
% Impervious Area (total)
0
48,287
60%
On-Site Buildings/Lots (sf)
On-Site Streets (sf)
11,715
0
Other On-Site (sf)
17,535
12,197
0
On-Site Parking (sf)
On-Site Sidewalks (sf)
Future (sf)
Off-site (sf)
Existing BUA (sf)
48,287Total
6,840
Impervious Surface Area
Offsite Drainage Area (sf)
Stream Index Number
Stream Class
Receiving Stream name
Basin Information Entire Site
NOTE: Please use the Storm-EZ calculation sheets to document the stormwater design
and create the O&M Agreement.
Discrete SCS Method,
Pre - PostCalculation Method
STORM-EZ
Version 1.4 Project Data
1/14/2019
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Pre-Development Land Use:
HSG CN %
A 39 76.17%
A 98 23.83%
Note: Enter BUA Draining to
Permeable Pavement Below
HSG
0.00 0.00%
1.86 23.83%
Existing Permeable Pavement (Infiltration):
Pavement Area Additional BUA
Soil
Infiltratio
n Rate
Gravel Void
Space
Total
Gravel
Depth
Orifice
Dia.
Orifice
Height
(sf) (sf) (in/hr) (%) (in) (in) (in)
100
DSD PAW Dgr
(in) (%) (in) (sf) (acres)
150 1.00 0.00
1.86 acres
0.00 acres
0.00 acres
0.00 acres
0.00 acres
1.86 acres
Pre-Development SCMs:
Imp. Open
(sf) (sf)
(cf) HSG 19327 61789
200
Rainfall Volume =1.86 cf
Natural Infiltration & ET =-1.51 cf
Disconnected Impervious Surfaces =0.00 cf
SCM Infiltration =0.00 cf
Permeable Pavement Infiltration =0.00 cf
Green Roof ET =0.00 cf
Post Filtration Discharge =0.00 cf
Total Runoff Reduction =-1.51 cf
Treated SCM Outflow =0.00 cf
Untreated Surface Runoff =0.35 cf
81,116
0
0
-5,486
-5,486
0
0
0
SCM Treatment:
acre-inches =1,274
The Pre-Development project area contains 19327 sf of built upon area, resulting in an overall density of 23.83%.
0
acre-inches =
acre-inches =
acre-inches =
acre-inches =
acre-inches =
acre-inches =
BUA %
SCM #
SCM #
From Land Use Tables: 81,116
Preserved Surface Waters & Non-Coastal Wetlands :
Runoff Reduction Components:
acre-inches =
6,760acre-inches =
acre-inches =
Design Storm Runoff Fate Summary:
81,116
Subtotal:
Jo Ellen Ammons Fieldhouse for Mars Hill University
(acres)
0.44Impervious
Pasture or Open Space 61,789
19,327
Mars Hill, NC MADISON County
French Broad River Basin
PRE-DEVELOPMENT LAND USE CALCULATIONS
Drainage Area #
(sf)Land-use
1.42
Area
User Defined Drainage Areas:Comp.
CNDescription
Area
(ac.)Area (sf.)
Subtotal:
Area (sf.)
WQ Volume
Provided
% Imp
Drainage Area
81,116 1.86
0
Downstream
SCM
Description
Total Site Area:
Land Use Summary:
Description
Preserved Coastal Wetlands :
NotesSCM #
Area DS SCM #
Has Synthetic
Liner?
Permeable Pavement + Additional BUA:
Green Roofs :
0
Existing Green Roofs:
HSG
SCM Type
D.S.
BMP
STORM-EZ
Version 1.4 Pre-Development
1/14/2019
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Permeable Pavement:
Infiltration
Rate Void Space
Total
Gravel
Depth
Orifice
Dia.
Orifice
Height
(sf) (acres) (sf) (acres) (in/hr) (%) (in) (in) (in)
500 0.00 0.00 No
DSD PAW Dgr
(in) (%) (in) (sf) (acres)
600 1.00 0.00 No
Residential Lot CN Calculator (Excluding R/W and dedicated open spaces):
Max Imp / Lot Woods / Lot
(ac.) (sf) (sf)
0.00
Remaining Land Use:
HSG CN (sf) (acres) %
A 39.0 32,829 0.75 40.47%
A 98.0 48,287 1.11 59.53%
N/A 0 0.00 0.00%
N/A 0 0.00 0.00%
81,116 1.86 100.00%
Land Excluded, or Partially Excluded, from Volume Calculations:(sf.) (ac.)
00.00
00.00
81,116 1.86
Rainfall Volume =1.86 cf
Natural Infiltration & ET =-0.99 cf
Disconnected Impervious Surfaces =0.00 cf
SCM Infiltration =-0.59 cf
Permeable Pavement Infiltration =0.00 cf
Green Roof ET =0.00 cf
Post Filtration Discharge =0.00 cf
Total Runoff Reduction =-1.57 cf
Treated SCM Outflow =0.00 cf
Untreated Surface Runoff =0.29 cf
Pre-Development Runoff =0.35 cf
Difference =-0.06 cf
CommentsRetrofit?
Drainage Area #
Down-
stream
SCM
Additional BUA
SCM #
Downstream
SCM #
HSG
Avg Lot Size
Pavement Area
% Imp.(sf.)
Permeable Pavement + BUA:
Sub-Total:
Green Roofs:
# of Lots
Land-Use
Impervious
Lot Area
Open Space (Managed Open Space)
Total Site Area:
Surface Waters & Non-Coastal Wetlands :
Green Roofs :
Coastal Wetlands :
acre-inches =
-2,132
0
-5,709
Jo Ellen Ammons Fieldhouse for Mars Hill University
Mars Hill, NC MADISON County
French Broad River Basin
Detention
Check
Has
Synthetic
Liner?
Infiltration
Check
POST-DEVELOPMENT LAND USE CALCULATIONS
Pvmt Type
SCM #
Area
Runoff Reduction Components:
Design Storm Runoff Fate Summary:
acre-inches =
acre-inches =
acre-inches =
acre-inches = -3,577
acre-inches =
0
acre-inches =
0
acre-inches =0
acre-inches =
0
SCM Treatment:
1,051
acre-inches =-223
acre-inches =1,274
The Post-Development project area contains 48287 sf of built upon area, resulting in an overall density of 59.53%.
Area
Open Space / Lot
(sf)
6,760
acre-inches =
STORM-EZ
Version 1.4 Post Development
1/14/2019
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Impervious
(sf)
48,287 (cf) (cf) (cf) (cf) (cf) (cf)
700 Bio. Cell Bioretention w/ IWS A 32,345 67% 74%1125 2132 2132 2132 0 0 100%
Rainfall Volume =1.86 acre-inches =cf
Natural Infiltration & ET =-0.99 acre-inches = cf
Disconnected Impervious Area =0.00 acre-inches = cf
SCM Infiltration =-0.59 acre-inches = cf
Permeable Pavement Infiltration =0.00 acre-inches = cf
Green Roof ET =0.00 acre-inches = cf
Post Filtration Discharge =0.00 acre-inches = cf
Total Runoff Reduction =-1.57 acre-inches =cf
SCM Treatment:
Treated SCM Outflow =0.00 acre-inches =cf
Untreated Surface Runoff =0.29 acre-inches =cf
0.35 acre-inches =cf
-0.06 acre-inches =cf
STORMWATER CONTROL MEASURES
% of SCM
Volume
Utilized
Post
Filtration
Outflow
Treated
Outflow
Type of Device
SCM
# Name / Location
Contributing Area
HSG
24,283
% of Total
Impervious
Area
% of Total
Pervious
Area
Storage
Volume
Offsite Impervious
Area Treated
Infiltration &
ET
0 sf
Total
Inflow
Volume
Enter only runoff volume below that will be infiltrated or drawn down over 2 to 5 days. Additional volume provided in devices should not be entered in this worksheet.
Drawdown time requirement applies to all storm events.
Drainage Area #
PROPOSED SIPs & STRUCTURAL RUNOFF VOLUME CONTROLS
Jo Ellen Ammons Fieldhouse for Mars Hill University
Mars Hill, NC MADISON County
French Broad River Basin
0
24283 sf open space entered
compared to 32829 sf total
open space.
Pervious
(sf)
32,829
1,274
Warnings:
Design Storm Runoff Fate Summary:
The Post-Development project area contains 48287 sf of built upon area, resulting in an overall density of 59.53%.
0
0
**VOLUME MATCHING ACHIEVED**
Difference =
Pre-Development Runoff =
0
1,051
67% of total
impervious
area.
74% of total
pervious
area.
Runoff Reduction Components:
-3,577
32345 sf impervious area entered
compared to 48287 sf total impervious.
Down-
stream SCM
#
Drainage
Area Inflow
Volume
-223
-5,709
-2,132
0
6,760
STORM-EZ
Version 1.4 Stormwater Controls
1/14/2019
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Compliance Storm = First Flush Storm - Rainfall Depth = 1 inch
Drainage Area #
FATE OF RAINFALL
Select Storm:
The"Fate of Rainfall" charts display the hydrologic processes to which rainfall volumes are subjected based on the combinations of land use, soil type, and stormwater controls entered by the user. The charts are designed to display the stormwater
plan in a form which illustrates changes to the hydrologic cycle which result from urbanization and various stormwater management strategies.
Mars Hill, NC MADISON County
French Broad River Basin
First Flush
Jo Ellen Ammons Fieldhouse for Mars Hill University
First Flush Storm - Rainfall Depth = 1 inch
VOLUME MATCHING SCALE
Volume Matching Threshold
Basic Treatment Threshold
BASIC TREATMENT SCALE
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Infiltration and ET ‐ 5709 cf Treated Outflow from BMPs ‐ 0 cf Untreated Surface Runoff ‐ 1051 cf% of Total Rainfall VolumePost Development Fates
Post Filtration Outflow ‐ 0 cf Other
Infiltration by BMPs ‐ 2132 cf Permeable Pavement Infiltration ‐ 0 cf
Disconnected Impervious Infiltration ‐ 0 cf Green Roof Evapotranspiration ‐ 0 cf
Infiltration and ET ‐ 3577 cf
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Infiltration and ET ‐ 5486 cf Treated Outflow from BMPs ‐ 0 cf Untreated Surface Runoff ‐ 1274 cf% of Total Rainfall VolumePre Development Fates
Infiltration and ET ‐ 5486 cf Green Roof Evapotranspiration ‐ 0 cf
Disconnected Impervious Infiltration ‐ 0 cf Permeable Pavement Infiltration ‐ 0 cf
Infiltration by BMPs ‐ 0 cf Other
Post Filtration Outflow ‐ 0 cf
FATE OF RAINFALL GRAPHS
STORM-EZ
Version 1.4 Rainfall Fate Graph
1/14/2019
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TIME OF CONCENTRATION CALCULATIONS:
Pre-Development
Length (ft) Slope (ft/ft)Tt (hrs)
400 0.015 0.06
Length (ft) Slope (ft/ft) n-value
Flow Area
(ft2)Tt (hrs)
Channel Flow:
Channel Flow:
Pre-development Tc =5.00 min (Minimum 5 minutes)
Post Development
Length (ft) Slope (ft/ft)Tt (hrs)
60 0.015 0.02
Length (ft) Slope (ft/ft) n-value
Flow Area
(ft2)Tt (hrs)
Channel Flow:380 0.01 0.012 1.5 0.01
Channel Flow:
Post-development Tc =5.00 min (Minimum 5 minutes)
ADJUSTED CURVE NUMBER CALCULATIONS:
Pre-Development
F.F. P90 P95 1-Yr 2-Yr 10-Yr 25-Yr 50-Yr 100-Yr
Rainfall (in) = 1.00 1.39 1.88 2.22 2.66 3.79 4.48 5.03 5.58
Q*(in) =0.19 0.28 0.39 0.47 0.58 0.87 1.09 1.30 1.53
CNadj =86 82 77 74 71 64 61 60 58
Post Development
F.F. P90 P95 1-Yr 2-Yr 10-Yr 25-Yr 50-Yr 100-Yr
Rainfall (in) = 1.00 1.39 1.88 2.22 2.66 3.79 4.48 5.03 5.58
Q*(in) =0.16 0.38 0.67 0.87 1.13 1.81 2.25 2.62 3.00
CNadj =84 85 84 83 82 79 78 77 76
PEAK FLOW CALCULATIONS:
F.F. P90 P95 1-Yr 2-Yr 10-Yr 25-Yr 50-Yr 100-Yr
Pre-Development
Q* (in) 0.19 0.28 0.39 0.47 0.58 0.87 1.09 1.30 1.53
qu (csm/in)809.52 931.69 931.69 931.69 931.69 931.69 931.69 931.69 931.69
Q (cfs) 0.44 0.76 1.07 1.29 1.57 2.35 2.96 3.52 4.14
Post Development
Q* (in) 0.16 0.38 0.67 0.87 1.13 1.81 2.25 2.62 3.00
qu (csm/in)666.59 931.69 931.69 1165.98 1165.98 1165.98 1165.98 1165.98 1165.98
Q (cfs) 0.30 1.03 1.81 2.95 3.83 6.14 7.65 8.89 10.17
-31.8% 35.5% 69.2% 128.7% 144.3% 161.3% 158.0% 152.4% 145.9%
Analysis Area = 1.86 Acres (0.003 sq. miles)
Sheet Flow:
Shallow Flow:
Sheet Flow:
Shallow Flow:
Wetted Perimeter (ft)
2.4
Sheet Flow:
Shallow Flow:
**Note: To decrease Post-development peak flows - increase storage volume being drawdown or infiltrated or lengthen post-
development time of concentration. See LID HELP for more information.
Wetted Perimeter (ft)
Sheet Flow: Paved or Bare Soil
Surface Cover
Analysis Area = 1.86 Acres (0.003 sq. miles)
Jo Ellen Ammons Fieldhouse for Mars Hill University
Mars Hill, NC MADISON County
Shallow Flow:
Drainage Area #
Surface Cover
Unpaved
French Broad River Basin
ADDITIONAL CALCULATIONS
STORM-EZ
Version 1.4 Peak Flow Calcs
1/14/2019
Page 10 of 13
BIORETENTION CELL1Drainage area numberEntire SiteTotal coastal wetlands area (sq ft)N/A - Parking / driveway (sq ft)17535 sfTotal surface water area (sq ft)N/A - Sidewalk (sq ft)12197 sfTotal drainage area (sq ft)81116 sf - Roof (sq ft)11715 sfBUA associated with existing development (sq ft) 193277 sf - Roadway (sq ft) sfProposed new BUA (sq ft)48287 sf - Other, please specify in the comment box below (sq ft) 6840 sfPercent BUA of drainage area59.5 percentTotal BUA (sq ft)48287 sfDesign rainfall depth (in)1.0 inMinimum volume required (cu ft)-Design volume of SCM (cu ft)1125 cf#1 Is the SCM sized to treat the SW from all surfaces at build-out? Yes#7 If applicable, with the SCM be cleaned out after construction?Yes#2 Is the SCM located on or near contaminated soils? No#8 Does the mainetenance access comply with General MDC (8)?Yes#3 What are the side slopes of the SCM (H:V)? 3:1#9 Does the drainage easement comply with General MDC (9)?No#3 Does the SCM have retaining walls, gabion walls or other engineered side slopes? No#10 If the SCM is on a single family lot, does the plat comply with General MDC (10)?#4 Are the inlets, outlets, and receiving stream protected from erosion (10-year storm)? Yes#11 Is there an O&M Agreement that complies with General MDC (11)?Yes#5 Is there a a bypass for flows in excess of the design flow?Yes#12 Is there an O&M Plan that complies with General MDC (12)?Yes#6 What is the method for dewatering the SCM for maintenance?Other#13 Was the SCM designed by an NC licensed professional?Yes#1 SHWT elevation (fmsl)< 2220.5 ft. #6 Percentage of medium to coarse washed sand by volume 75-85%#1 Bottom of the bioretention cell (fmsl) 2225.32 ft. #6 Percentage of fines (silt and clay) by volume 8-15%#1 Distance from bottom to SHWT (feet) > 2 ft. #6 Percentage of organic matter by volume 5-10%#2 Surface area of the bioretention cell (square feet) 1930 sf#6 Type of organic materialPine bark fines#2 Design volume of the bioretention cell (cubic feet) 1125 cf#7 Phosphorus Index (P-Index) of media (unitless) <50#2 Ponding depth of the design storm (inches) 7 in#8 Will compaction be avoided during construction?Yes#3 Is the bioretention cell used for peak attenuation? No#9 Will cell be maintained to a one inch/hour standard? Yes#3 Depth of peak attenuation over planting surface (in)7 in #10 Describe the planting plan:#3 Height of peak attenuation outlet above the planting surface (in)7 in#4 Infiltration rate of the in situ soil (inch/hour)See Note Below#4 Diameter of the underdrain pipes (if applicable)6 in#4 Does the design include Internal Water Storage (IWS)? Yes #11 Depth of mulch, if applicable (inches) N/A#4 if so, elevation of the top of the IWS (fmsl) 2227 ft #11 Type of mulch, if applicableN/A#4 Elevation of the planting surface (fmsl) 2228.5 ft #12 How many clean out pipes are being installed? 2#5 Will the cell contain trees and shrubs? No#12 Briefly describe the pretreatment that will be used:#5 Media depth (inches)30 inTHE DRAINAGE AREABIORETENTION CELL MDC FROM 02H .1052Per the USGS Soil Survey the in-situ soils are categorized as somewhat excessively drained and hydrologic soil group A.Break down of BUA in the drainage area (both new and existing):COMPLIANCE WITH THE APPLICABLE STORMWATER PROGRAMStormwater program(s) that apply (please specify):NCDEQ Phase II MSI or UA Post Construction StormwaterGENERAL MDC FROM 02H .1050ADDITIONAL INFORMATIONPlease use this space to provide any additional information about this bioretention cell that you think is relevant to the review:The bioretention cell will be soded with a non-clumping, deep rooted species that are NOT grown from a soil with an impenetrable layer (like clay).No pretreatment devices were designed as part of this bioretention cellJo Ellen Ammons Fieldhouse at Mars Hill UniversityBioretention210:59 AM 1/14/2019
2 inches per hour
q = K * dH/L 2 = K = hydraulic conductivity of media (inch per hour)
3 = dH = change in head (height of water) (ft)
q = 2.4 inch per hour per unit area 2.5 = L = thickness of soil layer (ft)
Q = q * A/12 inches per foot/3600 seconds Q = flow rate (cfs)
1930 = A = surface area
Q = 0.107222
D = 16 * (Q * n / (s^0.5))^(3/8)
D =  diameter of pipes (inches)
D = 6.512183 0.536111 = Q = flow rate w/ 5x safety factor (cfs)
0.012 = n = manning coefficient
0.005 = s = slope of pipe (assume 0.5%)
Number of 6" Pipes Required in the Underdrain
per NCDEQ Stormwater Design Manual = 2
reference:https://files.nc.gov/ncdeq/Energy%20Mineral%20and%20Land%20Resources/Stormwater/BMP%20Manual/A‐5%20%20Common%20Structures%20and%20Materials.pdf
Infiltration Rate of Media (1‐6 inches per hour required, 1‐2
inches per hour preferred)
User Input Data
Calculated Value
Reference Data
Designed By:ZPR Date:1.10.2019
Checked By:CB Date:1.10.2019
Company:McGill Associates
Project Name:MHU Fieldhouse
Project No.:16.00164
Site Location (City/Town)Mars Hill, NC
Rip Rap I.D.Pipe #2 outlet
Total Drainage Area (acres)-
Rational Method for Flow
Outlet pipe diameter, Do (in.)6
Tailwater depth (in.)6
Minimum/Maximum tailwater?Max TW (Fig. 8.06b)
Discharge (cfs)1.4
Velocity (ft./s)7.85
Minimum TW Maximum TW
Figure 8.06a Figure 8.06b
Riprap d50, (ft.)-0.25
Minimum apron length, La (ft.)-3
Apron width at pipe outlet (ft.)-1.5
Apron shape - trapezoid
Apron width at outlet end (ft.)-3.5
Minimum TW Maximum TW
Max Stone Diameter, dmax (ft.)- 0.375
Minimum TW Maximum TW
Apron Thickness(ft.)- 0.5625
User Input Data
Calculated Value
Reference Data
Designed By:ZPR Date:1.10.2019
Checked By:CB Date:1.10.2019
Company:McGill Associates
Project Name:MHU Fieldhouse
Project No.:16.00164
Site Location (City/Town)Mars Hill, NC
Rip Rap I.D.Pipe #3 outlet
Total Drainage Area (acres)-
Rational Method for Flow
Outlet pipe diameter, Do (in.)12
Tailwater depth (in.)6
Minimum/Maximum tailwater?Max TW (Fig. 8.06b)
Discharge (cfs)3.1
Velocity (ft./s)5.3
Minimum TW Maximum TW
Figure 8.06a Figure 8.06b
Riprap d50, (ft.)-0.25
Minimum apron length, La (ft.)-6
Apron width at pipe outlet (ft.)-3
Apron shape - trapezoid
Apron width at outlet end (ft.)-7
Minimum TW Maximum TW
Max Stone Diameter, dmax (ft.)- 0.375
Minimum TW Maximum TW
Apron Thickness(ft.)- 0.5625
Return to Main Worksheet
Figure 8.06a: Design of outlet protection from a round pipe flowing full, minimum
tailwater condition (Tw<0.5 diameter)
Return to Main Worksheet
Figure 8.06b: Design of outlet protection from a round pipe flowing full, maximum
tailwater condition (Tw>=0.5 diameter)