20201042 Ver 1_10_Stormwater Impact Analysis_20200813

Stormwater Impact Analysis & Preliminary
Design of Stormwater Management Facilities
Genesis / May, 2019

GENESIS
DURHAM, NORTH CAROLINA
STORMWATER I M PACT ANALYSIS
PROJECT NUMBER:
DESIGNED BY:
DATE:
REVISED DATE:
SITE PLAN
KTH-17000
JOSH SHINN, PE
KELLI GARCIA) PE
HEATHER DEW, El
MARCH 2O19
MAY 2019
iJ
MCADAMS
2905 MERIDIAN PARKWAY
DURHAM, NORTH CAROLINA 27713
NC Llc. # C-0293

J MCADAMS
GENESIS
Storm water Impact Analysis
GENERAL DESCRIPTION
NARRATIVE > KTH-17000
Located north of the intersection of E Cornwallis Road and NC-147 in Durham County, NC is the project site for the
proposed Genesis development. The site is currently vacant but was originally developed as an office facility with
ancillary uses, along with associated drives and parking. On this approximately 104.61-acre site, the proposed
development will consist of light industrial uses and ultimately consist of buildings and parking and associated utility
infrastructure, landscaping, and stormwater control measures. This SIA accounts for the current phase of development
treated by four SCMs and a future phase to be treated by one SCM. The future phase will be submitted as a separate
project at a later date but will use this SIA. An overall project boundary of 104.61 acres was set to include all existing
and proposed development. The peak flow and nutrient export analysis were performed using the overall project
boundary.
The proposed development is in the Jordan Lake Basin, with portions of the stormwater runoff draining into Burdens
Creek and Northeast Creek. The site is not located within a Watershed Protection Overlay. According to the N.C.
Division of Water Quality Basin Wide Information Management System (BIMS), Burdens Creek [Stream Index # 16-41-
1-17-1-(0.3)] and Northeast Creek [Stream Index # 16-41-1-17-1-(0.3)] are classified as WS-V; NSW at this location.
Per Durham County regulations, stormwater management on this site shall meet the stormwater management
performance standards for development set forth in the Durham County Code of Ordinances. These are as follows:
Sec. 14-1S3. Design and performance standards.
Durham County has been included in the Falls Lake Nutrient Management Strategy, Neuse River Sensitive
Waters Management Strategy, and the Jordan Lake Nutrient Management Strategy. Accordingly, all
development6. and redevelopment to which this ordinance applies shall comply with the standards of this
section and of the official North Carolina Division of Water Quality Best Management Practice Manuals. The
approval of the stormwater permit shall require an enforceable restriction on property usage that runs with the
land, such as a recorded deed restriction or protective covenants, to ensure that future development and
redevelopment maintains the site consistent with the approved project plans:
(a) The following requirements shall apply to developments within the Neuse River Basin and within Falls
Lake Drainage Basin (Subject to the Falls Lake Nutrient Strategy):
(1) Developments shall plan for, and implement, stormwater management controls which will limit the
runoff generated from all surfaces by one inch of rainfall. The treatment volume shall be drawn down
pursuant to standards specific to each practice as provided in the most recent Best Management Practice
Manual approved by the North Carolina Department of Environment and Natural Resources/Division of
Water Quality. To ensure that the integrity and nutrient processing functions of receiving waters and
associated riparian buffers are not compromised by erosive flows, stormwater flows from the
development shall not contribute to degradation of waters of the State. At a minimum, the development
shall not result in a net increase in peak flow leaving the site from pre -development conditions for the
one-year, 24-hourstorm event.
creating experiences through experience 2905 Meridian Parkway, Durham, NC 27713 / 919. 361. 5000

J MCADAMS
NARRATIVE > COM-18010
(2) Developments shall plan for and implement stormwater management controls which will limit the
unit -area mass nitrogen load of runoff to 2.2 pounds/acre/year and limit the unit -area mass phosphorus
load of runoff to 0.33 pounds/acre. year.
(3) The developer shall determine the need for engineered storm water controls to meet these loading
rate targets by using the most recent Nutrient Accounting Tool approved by the North Carolina
Environmental Management Commission.
(4) Notwithstanding 15A NCAC28.104(q), redevelopment subject to this ordinance that would replace or
expand existing structures or improvements and would result in a net increase in built -upon area shall
have the option of either meeting a loading standards identified in subsection (a) or meeting a loading
rate that achieves the following nutrient loads compared to the existing development: 40 percent and 77
percent reduction for nitrogen and phosphorous, respectively.
(5) Developers who desire to pursue offsite reduction measures for developments subject to this
ordinance shall attain nitrogen and phosphorus loading rate reductions on -site that meet the following
criteria prior to using an offset measure:
(a) 30 percent or more reduction in both nitrogen and phosphorus loading from the untreated
conditions for any single family, detached and duplex residential development disturbing one half
acre but less than one acre.
(b) 50 percent or more reduction in both nitrogen and phosphorus loading from the untreated
conditions for any single family, detached and duplex residential development disturbing more
than one acre.
(c) 30 percent or more reduction in both nitrogen and phosphorus loading from the untreated
condition for other development, including multi family residential, commercial and industrial
development disturbing 12,000 square feet but less than one acre.
(d) 50 percent or more reduction in both nitrogen and phosphorus loading from the untreated
condition for other development, including multi family residential, commercial and industrial
development disturbing more than one acre.
(e) 30 percent or more reduction in both nitrogen and phosphorus loading from the untreated
condition for proposed redevelopment activities in a designated downtown area that would
replace or expand structures or improvements that existed as of December 2006.
A developer subject to this ordinance may achieve the additional reductions in nitrogen and phosphorus
loading required by this ordinance by making offset payments to the NC Ecosystem Enhancement
Program contingent upon acceptance of payments by that Program. A developer may propose other
offset measures to Durham County, including providing his or her own offsite or utilizing a private seller.
All offset measures permitted by this ordinance shall meet the requirements of 15 A NAC 028.0282 and
15A NCAC 028. 0240.
creating experiences through experience 2 of 6

J MCADAMS
NARRATIVE > COM-18010
(6) Plans for developments shall protect and maintain existing riparian areas in accordance with 15A
N.C.A.C. 2B.0233 which is hereby incorporated by reference, as well as the requirements of the Durham
City -County Unified Development Ordinance. Consistent with the requirements of 15A N.CA. C2B.02333,
no developments shall be approved which are proposed within the first 50 feet adjacent to a waterbody
that is shown on the most recent version of either the U.S. G.S. 7 % minute quadrangle topographic map
or the U.S.D.A Soil Survey
Of Durham County, North Carolina, unless the development can demonstrate to the stormwater
administrator's satisfaction that the North Carolina Department of Environment and Natural
Resources/Division of Water Quality has approved the development.
(b) The following requirements shall apply to developments within the Neuse River Basin and outside Falls Lake
Drainage Basin (Subject to Neuse River Nutrient Sensitive Waters Management Strategy):
(1) Developments shall plan for and implement storm water management controls which will limit the
nitrogen load of runoff to 3.6 pounds/acre/year. Developers who have obtained an offset by
participation in the North Carolina Wetland Restoration Fund established by the North Carolina
Department of Environment and Natural Resources, shall plan for and implement management controls
which will limit the nitrogen load of runoff from the site to six pounds /acre/year for single family,
detached and duplex residential development and ten pounds per acre year for other development.
Nitrogen export calculations shall be made using a formula approved by the County Engineer, or
designee.
(2) Developments shall plan for, and implement stormwater management controls which will ensure that
there is no net increase in peak flow leaving the site from the predevelopment conditions for the one-year
24- hourstorm, of more than ten percent. If the development results in an increase of greater than ten
percent, the developer will be responsible for installing measures which will result in no net increase. The
some methodology must be used for calculating both the pre- and post -development flow rates.
(3) Plans for developments shall protect and maintain existing riparian areas in accordance with 15A
N.C.A.C. 2B.0233 which is hereby incorporated by reference as well as the requirements of the Durham
City -County Unified Development Ordinance. Consistent with the requirements of 15A N.C.A.C2B 0233,
no developments shall be approved which are proposed within the first 50 feet adjacent to a waterbody
that is shown on the most recent version of either the U.S. G.S. 71/2-minute quadrangle topographic map
or the U.S.D.A. Soil Survey of Durham County, North Carolina, unless the developer can demonstrate to
the County Engineer, or designee's satisfaction that the North Carolina Department of Environment and
Natural Resources/Division of Water Quality has approved the development.
(c) The following requirements shall apply to developments outside the Neuse River Basin:
(1) Developments shall plan for and implement storm water management controls which shall be
designed to control and treat the runoff generated from all surfaces by one inch of rainfall. The
treatment volume shall be drawn down pursuant to standards specific to each practice as provided in the
most recent Best Management Practice Manual approved by the North Carolina Department of
Environment and Natural Resources/Division of Water Quality. To ensure that the integrity and nutrient
processing functions of receiving waters and associated riparian buffers are not compromised by erosive
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J MCADAMS
NARRATIVE > COM-18010
flows, storm water flows from the development shall not contribute to degradation of waters of the State.
At a minimum, the development shall not result in a net increase in peak flow leaving the site from pre -
development conditions for the one-year, 24-hour storm event.
(2) Developments shall plan for, and implement, stormwater management controls shall be designed to
have a minimum of 85% average annual removal for Total Suspended Solids (TSS)
(3) Developments shall plan for, and implement, stormwater management
controls which will limit the unit -area mass nitrogen load of runoff to 2.2 pounds/acre/year and limit the
unit -area mass phosphorus load of runoff to 0.82 pounds/acre/year.
(4) The developer shall determine the need for engineered storm water controls to meet these loading
rate targets by using the most recent Nutrient Accounting Tool approved by the North Carolina
Environmental Management Commission.
(5) Notwithstanding 15A NCAC 28.104 (q), redevelopment subject to this ordinance that would replace
or expand existing structures or improvements and would result in a net increase in built -upon area shall
have the option of either meeting the loading standards identified in subsection (a) or meeting a loading
rate that achieves the following nutrient loads compared to the existing development: 35 percent and 5
percent reduction for nitrogen and phosphorus, respectively.
(6) Plans for developments shall protect and maintain existing riparian areas. No developments shall be
approved which are proposed within the first 50 feet adjacent to a waterbody that is shown on the most
recent version of either the U.S.G.S. 7112 —minute quadrangle topographic map or the U.S. D.A. Soil
Survey of the Durham County, North Carolina.
(7) Notwithstanding the foregoing, developments may be approved within the first 50 feet adjacent to a
waterbody that is shown on the most recent version of either the U.S.G.S 7112 —minute quadrangle
topographic map or the version U.S. D.A Soil Survey of Durham County, North Carolina provided:
(a) For streams, a stream delineation is performed by a person selected by the county engineer
from an approved list, which is to be compiled by the county engineer, to do stream delineations
and presented to the county engineer which, to the county engineer's satisfaction, shows that the
stream shown on the most recent version of either the U.S. G.S. 7 % -minute quadrangle
topographic map or the U.S. D.A. Soil Survey of Durham County, North Carolina does not exist.
Any person requesting such a stream delineation to be performed as provided in this subsection
shall make application to the county engineer for the stream delineation to be done and shall pay
a fee to cover the cost of said delineation in an amount as determined by the board of
commissioners.
(b) For ponds and lakes, that the ponds or lakes are manmade and are located outside natural
drainage ways.
(8) Developers who desire to pursue offsite offset reduction measures for developments subject to this
ordinance shall attain a maximum nitrogen loading rate on -site of six pounds per acre per year for single -
creating experiences through experience 4 of 6

J MCADAMS
NARRATIVE > COM-18010
family, detached and duplex residential development and ten pounds per acre year for other development,
including multi family residential, commercial, and industrial and shall meet any requirements for
engineered stormwater controls otherwise imposed by this ordinance. A developer subject to this
ordinance may achieve the additional reductions in nitrogen and phosphorus loading required by this
ordinance by making offset payments to the NC Ecosystem Enhancement Program contingent upon
acceptance of payments by that Program. A developer may propose other offset measures to Durham
County, including providing his or her own offsite or utilizing a private seller. All offset measures permitted
by this ordinance shall meet the requirements of 15A NCAC 028.0273 (2) through 4) and 15A NCAC
028.0240.
(9) Plans for developments shall protect and maintain existing riparian areas in accordance with 15A
N.C.A.C. 28.0233 which is hereby incorporated by reference, as well as the requirements of the Durham
City -County Unified Development Ordinance. Consistent with the requirements of 15A N.C.A.C.
28.02671..02681..0269, no developments shall be approved which are proposed within the first 50 feet
adjacent too waterbody that is shown on the most recent version of either the U.S. G.S. 7 % -minute
quadrangle topographic map or the U.S. D.A. Soil Survey of Durham County, North Carolina, unless the
developer can demonstrate to the County Engineer, or designee's satisfaction that the North Carolina
Department of Environment and Natural Resources/Division of Water Quality has approved the
development. (Ord. of 2-26-01, § 1; Ord. of 4-12-04, § 1; Ord. of 6-11-12, § 1)
To meet the above Durham County standards, four stormwater wet ponds are proposed at this time. A fifth wet pond
is analyzed in this report for a future phase of development not part of the current site plan. Please refer to the
appropriate sections of this report for additional information.
CALCULATION METHODOLOGY
■ Rainfall data for the Durham County, NC region is from NOAA Atlas 14. This data describes a depth -duration -
frequency (DDF) table describing rainfall depth versus time for varying return periods in the Durham County,
NC area. These rainfall depths are input into the meteorological model within PondPack for peak flow rate
calculations. Please reference the rainfall data section within this report for additional information.
■ Using latest soils data found from NRCS Web Soil Survey, the on -site soils were determined to be from
hydrologic soil group (HSG) 'D' soils. Since the method chosen to compute both pre- and post -development
peak flow rates and runoff volumes is dependent upon the soil type, care was taken when selecting the
appropriate Soil Conservation 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 on -site pre -
development conditions were taken from field survey by McAdams. Land cover conditions for the onsite post -
development condition were taken from the proposed site plan.
■ The time of concentration was calculated using SCS TR-55 (Segmental Approach, 1986). The Tc flow path was
divided into three segments: overland flow, concentrated flow, and channel flow. The travel time was then
computed for each segment, from which the overall time of concentration was determined by taking the sum
of each segmental time. The post -development times of concentration to the proposed stormwater
management facility is assumed to be 5 minutes. This provides a conservative estimate of facility size for
design purposes.
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J MCADAMS
NARRATIVE > COM-18010
■ Both the existing topography located within the property boundary and the remainder of the topography is
from Durham County GIS data. The remainder of the topography is from Durham County GIS data. Please refer
to the pre- and post -development watershed maps for more information.
■ PondPack Version V8i, by Bentley Systems, Inc., was used in determining the pre- & post -development peak
flow rates for the 1- and 100-year storm events, as well as routing calculations for the proposed stormwater
management facilities.
For 100-year storm routing calculations, a "worst -case" condition was modeled in order to insure the
proposed facility would safely pass the 100-year storm event. The assumptions used in this scenario are as
follows:
o The starting water surface elevation in the facility, just prior to the 100-year storm event, is at the
top of riser. This scenario could occur as a result of a clogged primary orifice or a rainfall event that
lingers for several days. This could also occur as a result of several rainfall events in a series, before
the low -flow orifice has an opportunity to draw down the storage pool.
o Freeboard is provided between the peak elevation during the "worst -case" scenario and the top of
the dam for the proposed facility, which is consistent with the previously approved as -built
certification package.
DISCUSSION OF RESULTS
PEAK RUNOFF CONTROL REQUIREMENTS
The peak flow for the 1-year storm meets peak flow requirements at all points of analysis on site. Please refer to the
Summary of Results for the reduction or preservation of flows from the pre- to post- development condition.
POLLUTANT AND NUTRIENT CONTROL REQUIREMENTS
All proposed SCMs are designed to the Minimum Design Criteria of the NC Stormwater Design Manual. Additionally,
the amount of added impervious to the site will receive water quality treatment from a primary SCM. The proposed
development is treated for 85% TSS removal per the Durham County Code of Ordinances using the proposed primary
SCMs to capture runoff from the impervious areas of the site. Because this project is a redevelopment, only the
increase in impervious is subject to TSS removal requirements.
Nutrient calculations are provided for reference only.
CONCLUSION
If the development on this tract is built as proposed within this report, then the requirements set forth in Durham
County regulations will be met without additional stormwater management facilities. However, modifications to the
proposed development may require that this analysis be revised. Some modifications that would require this analysis
to be revised include:
1. The proposed site impervious surface exceeds the amount accounted for in this report.
2. 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.
creating experiences through experience 6 of 6

NUTRIENT AND TSS CALCULATIONS
GENESIS
KTH-17000

GENSIS TSS SUMMARY
KTH-17000
TOTAL SUSPENED SOLIDS REMOVAL
sq. ft. ac.
Existing Impervious 886,435 20.35
Total Post -Development Impervious 1,760,309 40.41
Increase in Impervious (subject to TSS removal) 873,874 20.06
Impervious Area Treated by SCMs 1,744,234 40.04
SCM SUMMARY
sq. ft.
395,933
I ac.
9.09
SCM 'A'
SCM 'B'
323,216 7.42
SCM 'C'
359,708 8.26
SCM 'D'
333,283
7.65
SCM 'E'
332,094
7.62
TOTAL
1,744,234 40.04
K. GARCIA, PE
5/9/2019

Proiect Information
Yellow cells require data for
PROJECT AREA RUNOFF and
NUTRIENT TREATMENT
calculations
Green cells require data for
NUTRIENT TARGETS,
BUYDOWN, & CREDIT/DE81
calculations
Project Name:
Genesis
Submission Date:
03/25/2019
Project Area (ft):
4,556,597 ftz
Disturbed Area (ft):
4,556,597 ft2
Development Land Use Type:
Industrial
Development Activity Type:
Redevelopment
Designated Downtown Area?
no
Project Location/Address:
3029 East Cornwallis Road
County:
Durham
Local Jurisdiction:
Durham County
Project Latitude Coordinates:
35.916600 N
Project Longitude Coordinates:
-78.865600 W
Precipitation Station:
Durham
Physiographic Region:
Triassic Basin
Nutrient Management Watershed:
Jordan Lake
Subwatershed:
Jordan - Upper New Hope
Phosphorus Delivery Zone:
Jordan - 060140
lKelli
Nitrogen Delivery Zone:
Jordan - 060140
Project Designer and Contact Phone
Number / Email:
Garcia / [e-mail]
Part of Common Development Plan?
no
Project Owner Type:
Private
Project Description:

PROJECT AREA LAND COVERS
TN
EMC
(mg/L)
1.18
TP
EMC
(mg/L)
0.11
Pre-
Project
Area (ft)
220,381
Post -
Project
Area (ft)
688,975
Roof
Roadway
1.64
0.34
145,648
Parking/Driveway/Sidewalk
1.42
0.18
520,406
1,071,334
Protected Forest
0.97
0.03
2,435,034
1,078,497
Other Pervious/Landscaping
2.48
1.07
1,235,128
1,618,905
CUSTOM LAND COVER 1
CUSTOM LAND COVER 2
CUSTOM LAND COVER 3
LAND TAKEN UP BY SCM 1.18 0.11 98,886
LAND COVER AREA CHECK
Net Change of Land Covers (ft): 1,502,185
Total Project Area Entered (ft): 4,556,597
Total Pre -Project Calculated Area (ft): 4,556,597
Total Post -Project Calculated Area (ft): 4,556,597
Equations Used and Project Area Calculations
SIMPLE METHOD Stormwater Runoff Volume Generated, V
Runoff Coefficient R v V = Pi * Rv * (P/12) * A
R = 0.05 + (0.009 *1) where A = drainage area (ft)
where I = percent impervious (%) Pi = fraction of rain events with runoff
Average Annual Pollutant Load, L P = average annual rainfall depth (in)
L= (Pi*R *(P/12))*(C*A*2.72)
where C = event mean concentration (mg/L)
Pre -Project:
Post -Project:
A = 104.6051
ac
A = 104.6051
ac
P= 47.81
in.
P= 47.81
in.
V = 3677622
ft3
V = 6834618
ft3
1 = 19%
1 = 41%
R =0.23
R =0.42
Pi = 0.9
Pi = 0.9
CTN = 1.41
mg/L
CTN = 1.36
mg/L
CTP = 0.22
mg/L
CTP = 0.19
mg/L
LTN = 324.04
Ib/yr
LTN = 579.31
Ib/yr
LTP= 51.23
Ib/yr
LTP= 79.33
Ib/yr

Catchment ID
SCM ID
Type of SCM
Predominant hydrologic soil
group at SCM location
SCM Description
Design Storm Size (inches/24hrsj
Percent of Full Size
Hydrologic Value - Percent
Annual Effluent
Hydrologic Value - Percent
Annual Overflow
Hydrologic Value - Percent
Annual 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
Catchment Routing
(Source Catchment)
Catchment 1
Catchment 2
Catchment 3
Catchment 4
Catchment 5
Catchment 6
1
101
Wet Pond per MDC
D
1
102
1
103
2
201
Wet Pond per MDC
D
2
202
2
203
3
301
3
302
Wet Pond per MDC
D
SCM A
SCM B
SCM C
1.00
1.00
1.00
100%
100%
100%
76%
76%
76%
16%
16%
16%
8%
8%
8%
0.15
0.15
0.15
1.22
1.22
1.22
0.11
1.18
0
W"
Catchments Draining to
SCM 101
Catchments Draining to
SCM 102
Catchments Draining to
SCM 103
0.11
1.18
0
Catchments Draining to
SCM 201
Catchments Draining to
SCM 202
Catchments Draining to
SCM 203
0.11
1.18
0
Catchments Draining to
SCM 301
Catchments Draining to
SCM 302
_ SCM ID: ML 102 103 202 Draining
301 302
SCM Drainage Area Land Covers Area Draining Directly to Area Draining Directly to Area Draining Directly to Area Draining Directly to Area Draining Directly to Area Draining Directly to Area Draining Directly to Area Draining Directly to
SCM 101 (ft2) SCM 102 (ft2) SCM 103 (ft2) SCM 201 (ft2) SCM 202 (ft2) SCM 203 (ft2) _ SCM 301 (ft2) - SCM 302 (ft2)
CUSTOM LAND COVER 2
CUSTOM LAND COVER 3
LAN D TAKEN UP BY SCM
TOTAL AREA DRAINING TO SCM
(Rel.
CATCHMENT AREA (ft):
20,825
623,666
623,666
0 0 534,932 0 0 533,018 0
534,932 533,018

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
Annual Effluent
Hydrologic Value - Percent
Annual Overflow
Hydrologic Value - Percent
Annual 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
Catchment Routing
(Source Catchment)
Catchment 1
Catchment 2
Catchment 3
Catchment 4
Catchment 5
Catchment 6
SCM Drainage Area Land Covers
CUSTOM LAND COVER 2
CUSTOM LAND COVER 3
LAND TAKEN UP BY SCM
TOTAL AREA DRAINING TOSCM
(fel:
CATCHMENT AREA (ft):
3
303
4 4 4
401 402 403
Wet Pond per MDC
D
SCM D
1.00
100%
76%
16%
8%
0.15
1.22
Catchments Draining to
SCM 303
0.11
1.18
0
Catchments Draining to Catchments Draining to Catchments Draining to
SCM 401 SCM 402 SCM 403
303 401
403
Area Draining Directly to Area Draining Directly to Area Draining Directly to Area Draininging
Directly to
SCM 303 (ft2) SCM 401 (ft2) SCM 402 (ft2) SCM 403 (ft2)

Catchment ID 5 5 5
SCM ID 501 502 503
Type of SCM Wet Pond per MDC
Predominant hydrologic soil D
group at SCM location
SCM Description SCM E
Design Storm Size (inches/24hrs)
Percent of Full Size
Hydrologic Value - Percent
Annual Effluent
Hydrologic Value - Percent
Annual Overflow
Hydrologic Value - Percent
Annual 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
Catchment Routing
(Source Catchment)
Catchment 1
Catchment 2
Catchment 3
Catchment 4
Catchment 5
I Catchment
6
1.00
100%
76%
16%
8%
0.15
1.22
0.11
Catchments Draining to Catchments Draining to Catchments Draining to
SCM 501 SCM 502 SCM 503
SCM ID:
502
503
-
Allowable Total land Use
Area Draining Directly to
Area Draining Directly to
Area Draining Directly to
Total Land Use Area
Post -Project Untreated
SCM Drainage Area Land Covers
SCM 501(ft2)
SCM 502 (ft2)
SCM 503 (ft2)
Treated By All SCMs (ftz)
Area to be Treated Based
Land Area (ftz)
toof
90,400
688,975
688,975
0
toadwav
0
0
0
CUSTOM LAND COVER 2
0
0
0
CUSTOM LAND COVER 3
0
0
0
LAND TAKEN UP BY SCM
TOTAL AREA DRAINING TO SCM
(Rel.
CATCHMENT AREA (ft):
15,544
98,886
98,886
0
527,433 0 0
527,433
2,724,701
4,556,597
1,831,896

Project Summary
Project Name:
Genesis
4,556,597 ft104.6051 acres Submission Date:
4,556,597 ft2 104.6051 acres March 25, 2019
Project Area (ft):
Disturbed Area (ft):
County:
Durham
Local Jurisdiction:
Durham County
Development Land Use Type:
Industrial
Owner Type:
Private
Development Activity Type:
Redevelopment
Designated Downtown Area?
no
Nutrient Management Watershed:
Jordan Lake
Subwatershed:
Jordan - Upper New Hope
Phosphorus Delivery Zone:
Jordan - 060140
Nitrogen Delivery Zone:
Jordan - 060140
Phosphorus Delivery
Factor (%):
89%
Nitrogen Delivery
Factor (%):
85%
Phosphorus Loading Rate Target (Ib/ac/yr):
Nitrogen Loading Rate Target (Ib/ac/yr):
Phosphorus Load Target at Site (lb/yr):
Nitrogen Load Target at Site (lb/yr):
Phosphorus Load Leaving Site w/SCMs (lb/yr):
67.50
Nitrogen Load Leaving Site w/SCMs (lb/yr):
495.57
P Offsite Buy -Down Threshold Loading Rate (lb/ac/yr):
N Offsite Buy -Down Threshold Loading Rate
Total P Load Reduction Needed (lb/yr):
Total N Load Reduction Needed (lb/yr):
P Load Treatment Balance at Site (lb/yr):
N Load Treatment Balance at Site (lb/yr):
P Load Treatment Balance at Lake (lb/yr):
N Load Treatment Balance at Lake (lb/yr):
Nutrient Export Summary
Percent Impervious (for runoff calculation) (%)
Pre -Project
Whole Site
Conditions
Post -Project
Whole Site
without SCMs
Post -Project Post -Project
Post Project
Whole Site with SCM-Treated
Untreated Area
SCMs Area
19.5%
40.8%
40.8%
67.6%
0.9%
Percent Built -Upon Area (BUA) (%)
19.5%
38.6%
38.6%
64.0%
0.9%
Annual Runoff Volume ft3/ r
3,677,622
6,834,618
6,289,745
5,909,433
380,313
Annual Runoff % Change (relative to pre-D)
0%
86%
71%
Total Nitrogen EMC (mg/L)
1.41
1.36
1.26
1.24
1.64
Total Nitrogen Load Leaving Site (lb/yr)
324.04
579.31
495.57
456.71
38.86
Total Nitrogen Loading Rate (Ib/ac/yr)
3.10
5.54
4.74
7.30
0.92
Total Nitrogen % Change (relative to pre-D)
0%
79%
53%
Total Phosphorus EMC (mg/L)
0.22
0.19
0.17
0.15
0.47
Total Phosphorus Load Leaving Site (lb/yr)
51.23
79.33
67.50
56.43
11.07
Total Phosphorus Loading Rate (Ib/ac/yr)
a49
a76
a65
0.90
a26
Total Phosphorus % Change (relative to pre-D)
0%
55%
32%

SCM/Catchment Summary
SCM ID and Type Volume TN Out (mg/L) TP Out (mg/L)
Reduction (%)
Catchment 1 8.44% 1.24 0.15
TN Out TP Out TN Reduction TP Reduction (%)
(lbs/ac/yr) (lbs/ac/yr) M
7.22
0.90
15.74%
18.79%
101: Wet Pond per MDC
8.44%
1.24
0.15
7.22
0.90
15.74%
18.79%
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
8.44%
1.24
0.15
6.99
0.87
15.60%
19.08%
201: Wet Pond per MDC
8.44%
1.24
0.15
6.99
0.87
15.60%
19.08%
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
8.44%
1.23
0.15
7.65
0.93
13.59%
8.46%
301: Wet Pond per MDC
8.44%
1.23
0.15
7.65
0.93
13.59%
8.46%
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
8.44%
1.24
0.15
7.51
0.93
15.21%
16.91%
401: NA
8.44%
1.24
0.15
7.51
0.93
15.21%
16.91%
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
8.44%
1.25
0.16
7.16
0.89
17.25%
22.19%
501: NA
8.44%
1.25
0.16
7.16
0.89
17.25%
22.19%
502: NA
0.00%
0.00
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%
603: NA 0.00%
0.00
0.00
0.00
0.00
0.00
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.