SW4211102_Design Calculations_20221130

Proiect Information
Project Name:
Store -It -Safe Self -Storage
Submission Date: 11/30/2022
Project Area (ft): 741186 ft2
Disturbed Area (ft): 74,186 ft2 i
Development Land Use Type: Commercial
Development Activity Type: Development - New
Designated Downtown Area? no
Project Location/Address: 7660 S NC Hwy 87, Graham, NC
County: Alamance
Local Jurisdiction:
==
Project Latitude Coordinates:
35.905410 N
Project Longitude Coordinates:
-79.306324 W
Precipitation Station: Burlington
Physiographic Region: Piedmont
Nutrient Management Watershed: Jordan Lake
Subwatershed: Jordan - Haw
Phosphorus Delivery Zone: Jordan - 050050
Nitrogen Delivery Zone: Jordan - 050050 _ .... _
Project Designer and Contact Phone
LAden
R. Stoltzfus, [e-mail]
Number /Email: '3
To4-ozo•7
Part of Common Development Plan?
Project Owner Type:
Project Description: 011111 III/
rARO`G•rjs�0
Commercial Self -Storage Facility w/ Sand Filter
• V
O
p2
I l �4Z-
�. "5' FNG1N�• A
��
Ri,S� %

Proiect Area Land Cover Characteristics
TN
PROJECT AREA LAND COVERS EMC
(mg/L)
Roof 1.18
Roadway 1.64
Parking/Driveway/Sidewalk 1.42
Protected Forest 0.97
Other Pervious/Landscaping 2.48
CUSTOM LAND COVER 1
CUSTOM LAND COVER 2
CUSTOM LAND COVER 3
LAND TAKE,N UP BY SCM 1.18
Post -
Project
Area (ft)
28,550
-0
29,632
0
13,832
TP
EMC
(mg/L)
Pre-
Project
Area (ft)
0.11
0
0.34
0
0.18
0
0.03
0
1 1.07
74,186
0.11
2,172
LAND COVER AREA CHECK
Net Change of Land Covers (ft): 60,354
Total Project Area Entered (ft): 74,186
Total Pre -Project Calculated Area (ft): 74,186
Total Post -Project Calculated Area (ft): 74,186
Equations Used and Protect Area Calculations
SIMPLE METHOD
Runoff Coefficient, R
Stormwater Runoff Volume Generated, V
V= Pi*Rv*(P/12)*A
where A = drainage area (ft)
pi = fraction of rain events with runoff
P = average annual rainfall depth (in)
R = 0.05 + (0.009 *1)
where I = percent impervious (%)
Average Annual Pollutant Load, L
L= (Pi *RV*(P/12))*(C*A*2.72)
where C = event mean concentration (mg/L)
Pre -Project:
i
A = 1.7031
a
P = 44.68
in.
V = 12430
ft3
1= 0%
R = 0.05
Pi = 0.9
CTN = 2.48
mg/L
CTP = 1.07
mg/L
LTN = 1.92
1 b/yr
LTP = 0.93
Ib/yr
A = 1.7031
a c
P = 44.68
in.
V = 194815
ft3
1= 81%
R = 0.78
Pi = 0.9
CTN = 1.31
mg/L
CTp = 0.16
mg/L
LTN = 15.96
Ib/yr
LTP _ 1.89
Ib/yr

3. SCM Characteristics
Catchment Routing
Catchments Draining to
(Source Catchment)
SCM 101
Catchment 1
no _
Catchment 2
Catchment
Catchment 4
_ ^
Catchment 5
Catchment 6
Catchments Draining to Catchments Draining to
SCM 102 SCM 103
SCM ID:
101
102
103
SCM Drainage Area Land Covers
Area Draining Directly to
SCM 101 (ft2)
Area Draining Directly to
SCM 102 (ft2)
Area Draining Directly to
SCM 103 (ft2)
Roof
28,550
Roadway
28,782
Parking/Driveway/Sidewalk
Protected Forest
64
Other Pervious/Landscaping
CUSTOM LAND COVER 1
CUSTOM LAND COVER 2
CUSTOM LAND COVER 3
LAND TAKEN UP BY SCM
2,172
TOTAL AREA DRAINING TO SCM
(ft2)'
59,568
0
0
CATCHMENT AREA (ftZ):
59,568
Allowable Total Land Use
Total Land Use Area
Treated By All SCMs (ft)
Area to be Treated Based
z
on Post -Project Areas (ft )
28,550
28,550
0
0
28 782
29,632
0
13,832
0
64
0
0
0
2,172
_---
0
2,172
59,568
74,186
Post -Project Untreated
Land Area (ftZ)
0
0
850
0
13,768
0 -
- 0
0
14,618

3. SCM Characteristics
SCM Characteristics
Catchment ID
SCM ID
Type of SCM
Predominant hydrologic soil
group at SCM location
SCM Description
Design Storm Size (inches/24hrs)
Percent of Full Size
Hydrologic Value - Percent Annua
Effluent
Hydrologic Value - Percent Annua
overflow
Hydrologic Value - Percent Annua
ET/Infiltrated
SCM Effluent TP EMC (mg/L)
SCM Effluent TN EMC (mg/L)
SCM Land Cover TP EMC (mg/L)
SCM Land Cover TN EMC (mg/L)
Drains to SCM ID
1 1 1
101 102 103
Sand Filter per MDC - Open
B
1.00
100%
85%
10%
4%

SCM/Catchment Summary
Volume TN Out TP Out
SCM ID and Type Reduction (%) TN Out (mg/L) TP Out (mg/L) (Ibs/ac/yr) (Ibs/ac/yr) TN Reduction (%) TP Reduction (%)'
Catchment 1 4.48% 1.21 0.12 10.00 1.01 10.96% 18.75%
101: Sand Filter per MDC Open 4.489/0 1.21 0.12 10.00 1.01 10.96% 18.75%
102: NA 0.00% 0.00 0.00 0.00 0.00 0.00% 0.00%
103: NA 0.00% 0.00 0.00 0.00 0.00 0.00% 0.00%
Catchment 2..
o
201: NA 0.00% " 0.00 0.00 0.00 0.00 0.00% 0.00%
202: NA 0.00% 0.00 0.00 0.00 0.00 0.00% 0.00%
203: NA 0.00% 0.00 0.00 0.00 0.00 0.00% 0.00%
Catchment 3 0.00% 0.00 0.00 0.00 0.00 0.00% 0.00% u
301: NA 0.00% 0.00 0.00 0.00 0.00 0.00% 0.00%
302: NA 0.00% 0.00 0.00 0.00 0.00 0.00% 0.00%
303: NA 0.00% 0.00 0.00 0.00 0.00 0.00% 0.00%
Catchment 4 0.00% 0.00 0.00 0.00 0.00 0.00% 0.00%
401: NA 0.00% 0.00 0.00 0.00 0.00 0.00% 0.00%
402: NA 0.00% 0.00 0.00 0.00 0.00 0.00% 0.00%
403: NA 0.00% 0.00 0.00 0.00 0.00 0.00% 0.00%
Catchment 5 0.00% 0.00 0.00 0.00 0.00 0.00% 0.00%
502: NA 0.00% .. �_. _r._._...�.._._ 0.00 0.00 0.00 0.00 0.00% 0.00%
sot: NA �_._. _ 0.000 0 00.M._...__... _ _ ._.,._..,.�
0.00 0.00 0.00 0.00% 0.00%
503: NA 0.00% 0.00 0.00 0.00 0.00 0.00% 0.00%
Catchment 6 0.00% 0.00 0.00 0.00 0.00 0.00% 0.00%
601: NA 0.00% 0.00 0.00 0.00 0.00 0.00% 0.00%
602: NA 0.00% 0.00 0.00 0.00 0.00 0.00% 0.00%
603: NA 0.00% 0.00 0.00 0.00 0.00 0.00% 0.00%
SCM rows in red have a data entry error for the SCM that makes an error in the calculation.

Proiect Summar
Project Name: Store -It -Safe Self -Storage
_.( )
Project Area ft2 74,186 ftZ
1.7031W acres Submission Date .
Disturbed Area (ft): 74,186 ftZ
1.7031 acres November 30, 2022
County: Alamance
Local Jurisdiction: Alamance County
Development Land Use Type: Commercial
Development Activity Type: Development - New
Owner Type: Private
Designated Downtown Area? no
Nutrient Management Watershed: Jordan Lake
Subwatershed:Jordan - Haw
Phosphorus Deliver Zone: Jordan - 050050
p y
w Nitrogen �____.......,
ogen Delivery Zone Jordan - 050050
Phosphorus De fiver Factor /o .
y ( ) . 67%
Nitrogen Delivery Factor (%):. 71%
Phosphorus Loading Rate Target (lb/ac/yr)
` 1.43
Nitrogen Loading Rate Target (ib/ac/yr)r 3.80
Phosphorus load Target at Site (lb/yr):l
2.44
Nitrogen Load Target at Site (lb/yr).l 6.47
Phosphorus Load Leaving Site w/SCMs (lb/yr):l
1.57
Nitrogen Load Leaving Site w/SCMs (lb/yr):l 14.27
P Offsite Buy -Down Threshold Loading Rate (lb/ac/yr):; 0.92
N Offsite Buy -Down Threshold Loading Rate 10.00
Total P Load Reduction Needed (lb/yr): -0.55
Total N Load Reduction Needed (lb/yr): 9.48
_ P Load Treatment Balance at Site (lb/yr): -0.87
N Load Treatment Balance at Site (fib/yr): 7.80
-
P Load Treatment Balance at Lake (Ib/yr). 0.58
_..y
_
N Load TBalance Lk
oareatment aance at Lake Ib : 5.54-
( /yr) �� �,
r-
Nutrient Export Summary
Percent Impervious (for runoff calculation) (%)
Percent Built -Upon Area (BUA) (%)
Annual Runoff Volume (ft3/yr)
Annual Runoff % Change (relative to pre-D)
Total Nitrogen EMC (mg/L)
Total Nitrogen Load Leaving Site (lb/yr)
Total Nitrogen Loading Rate (lb/ac/yr)
Total Nitrogen % Change (relative to pre-D)
Total Phosphorus EMC (mg/L)
Total Phosphorus Load Leaving Site (lb/yr)
Pre -Project Post -Project
Whole Site
Whole Site
Conditions
without SCMs
0.0%
81.4%
0.0% �
78.4%
12,430
194,815
0%
1467%
2.48
1.92
1.13
0%
1.07
0.83
Total Phosphorus Loading Rate (ib/ac/yr) ; 0.49
Total Phosphorus % Change (relative to pre-D) 0%
Post -Pro
Whole Site with S .. Post-Pro._...ect ... _ ....._
ect j
CM Treated Post -Project
SCMs Area Untreated Area
81.4% 99.9% __J_5.8%
78.4% 96.2% 5.8% -
186,318 181,305 5,013
1399%
1.31 1.23 1.21 1.91
15.96 14.27 13.67 0.60
9.37 8.38 10.00 1.78
0.16
0.14
1.89
1.57
1.11
0.92
128%
89%
0.12 0.59
1.38 0.18
1.0i 0,55

Supporting Calculations
R = 0.05 + (0.009 *1),
where I = percent impervious (%)
V=Pi* R *A*(P/12),
where A = area of catchment (ft2)
P = average annual rainfall depth (in)
L=((P*Pi*R)+(12))*(C*A*2.72)
where L = annual pollutant loading (Ibs)
P; = fraction of rain events that produce runoff (dec)
C = event mean concentration of pollutant (mg/L)
Vogt = Vin * (1- Red)
where V;, = inflow volume (ft3)
Red = volume reduction by SCM (%)
Lout = Vogt * EMCout * 6.243E-5
where Vo t= outflow volume (ft),
EMCO t = effluent median concentration (mg/L)
CATCHMENT 1, SCM 101
Type of SCM:
Sand Filter per MDC -
Open
Area Treated by SCM (ft):
59,568
Percent Impervious of Contributing Watershed (%):
100%
Runoff Coefficient, Rv:
0.95
Inflow Volume (ft):
189,803
Incoming Total Nitrogen Concentration (mg/L):
1.30
Annual Incoming Total Nitrogen Load (lbs):
15.36
Incoming Total Phosphorus Concentration (mg/L):
0.14
Annual Incoming Total Phosphorus Load (lbs):
1.70
Total Volume Leaving SCM (ft):
181,305
Outgoing Total Nitrogen Concentration (mg/L):
1.21
Annual Outgoing Total Nitrogen Load (lbs):
13.67
Outgoing Total Phosphorus Concentration (mg/L):
0.12
Annual Outgoing Total Phosphorus Load (lbs):
1.38
Annual Volume Reduction by SCM (ft):
8,497
Annual Volume Reduction by SCM (%):
4%
Annual Total Nitrogen Reduction by SCM (%):
10.96%
Annual Total Nitrogen Reduction by SCM (lb):
1.68
Annual Total Phosphorus Reduction by SCM (%):
18.75%
Annual Total Phosphorus Reduction by SCM (lb):
0.32

Nutrient Management Strategy Watershed - Nutrient Offset Credit Reporting Form
Please complete and submit the following information to the local government permitting your development project
to characterize it and assess the need to purchase nutrient offset credits. Contact and rule implementation
information can be found online at:
http://deg.nc.gov/about/divisions/water-resources/pla nning/nonpoint-source-management/nutrient-offset-
information
PROJECT INFORMATION
Applicant Name: Aiken Keppler
Project Name:' Store -It -Safe Self -Storage
Project Address: 7660 S NC Hwy 87, Graham, NC
Date: (mm/dd/yyyy) 11/30/2022 Development Land Use Type Commercial
County: Alamance Development Activity Type_ Development - New
Pre -Project Built -Upon Area %: 0.00% Project Latitude: 35.90541
Post -Project Built -Upon Area %: 78.43% Project Longitude:-79.306324
WATERSHED INFORMATION
Nutrient Management Watershed:
Subwatershed:
Jordan Lake
Jordan - Haw
N Offsite Threshold Rate (lb/ac/yr): 10.00
P Offsite Threshold Rate (lb/ac/yr): 0.92
Nitrogen Delivery Zone:
Jordan - 050050
Nitrogen Delivery Factor:
71%
Phosphorus Delivery Zone:
Jordan - 050050
Phosphorus Delivery Factor:
67%
NUTRIENT OFFSET REQUEST
Nitrogen Load Offset Needs
(A)
(B)
(C)
(D)
(E)
(F)
(G)
(H)
(L) (Where
Applicable)
Untreated
Treated
Loading Rate
Reduction
Project Size
Offset
Delivery
State Buy
Local Gov't
Loading Rate
Loading Rate
Target
Need
(ac)
Duration (yrs)
Factor (/o)
Down Amount
Buy Down
(Ibs/ac/yr)
(Ibs/ac/yr)
(Ibs/ac/yr)
(Ibs/ac/yr)
(Ibs)
Amount (Ibs)
B-C
D*E*F*G
9.37
8.38
3.80
4.58
1 1.7031
30
71%
166.09
Phosphorus Load Offset Needs
(A)
(B)
(C)
(D)
(E)
(F)
(G)
(H)
(L) (Where
Applicable)
Untreated
Treated Load
Loading Rate
Reduction
Project Size
Offset
Delivery
State Buy
Local Gov't
Load Rate
Rate
Target
Need
(ac)
Duration (yrs)
o
Factor (/o)
Down Amount
Buy Down
(Ibs/ac/yr)
(Ibs/ac/yr)
(Ibs/ac/yr)
(Ibs/ac/yr)
(Ibs)
Amount (Ibs)
B-C
D*E*F*G
1.11
0.92
1.43
-0.51
1 1.7031
30
67%
0.00
LOCAL GOVERNMENT AUTHORIZATION
Local Government Name:Alamance County
Staff Nam
Staff Emai
Local Government Authorizing Signatu