20220212 Ver 1_1101 Olive Branch Road_5th Submittal_SIA_20220411

Prepared by:
1101 Olive Branch Road
STORM WATER IMPACT ANALYSIS
1 101 Olive Branch Road
Durham, North Carolina
Horvath Associates Project Number: 1886
December 10, 2021
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Horvath Associates, P.A.
Engineers - Planners - Landscape Architects
16 Consultant Place, Suite 201
Durham, North Carolina 27707
[phone]

Table of Contents
Narrative
City of Durham Stormwater Site Plan Checklist
SCM Sizing Calculations
Nutrient Loading Calculations
Peak Runoff Analysis
Site -to -Drainage Area Analysis
Required Maps and Information

Narrative

A. Project Data
• Project Name: 1 101 Olive Branch Road
• PIN: 0860-84-52-7778DUR
• Address: 1 101 Olive Branch Road
• Stormwater Regulatory Basin: Falls Lake
• River Basin: Neuse
• Existing Impervious Area: 2,000 sf
• Proposed Impervious Area: 2,157,800 sf
• Area of Disturbance: 5,358,000 sf
• TMDL: None
• Watershed Protection Overlay: F/J-B
B. Site History
Aerial photographs indicate the site was completely forested between 1999 and 2013. The
below aerial photographs encompass the baseline date time frames that will govern the
regulations to this project. The City of Durham does not have any newer aerial
photography available at the project location, but photographs available from another
application indicate some of the wooded areas were cleared in 2015-2016.
1999 Aerial Photo

2013 Aerial Photo
C. Project Description
The project will involve clearing the site and constructing a single family and townhome
development.
D. Quantifying Land Disturbance and Changes in Impervious Surface
The project will involve greater than 12,000 sf of land disturbance and will add more
than 2,000 sf of new impervious area. This exceeds all thresholds found in the City of
Durham Stormwater performance Standards; therefore, the site will not be exempt from
any stormwater requirements.
E. Watershed Protection Overlays
The entire site is in the F/J-B watershed protection overlay.
F. Streams
There are several buffered streams located on the property. Buffers have been applied
per City of Durham requirements. Martin Branch drains through the middle of the site
south to north. There is a large wetland area that surrounds the stream.
G. Floodplains
Floodplain for Martin Branch splits the site in half south to north. A crossing of the
floodplain and floodway for Martin Branch is proposed and will require CLOMR/LOMR
approval by FEMA.

H. Applicable Requirements
Peak Runoff Requirements
Sec. 70-738. Peak runoff control requirements.(a)Purpose. The purpose of this section is
to ensure that the increases in volume, velocity, and peak flow of stormwater discharges
from development are addressed, in order to mitigate the impacts on downstream
properties and receiving waters. All development, including development that may be
exempt from pollutant reduction requirements set forth in remaining sections of this
article, is subject to the requirements of this section unless exempted in subsection (b)
below.
(b)Applicability; calculation of prior impervious area. This section 70-738 applies to
the following development, assessed in comparison to pre -development prior
impervious conditions as defined in subsections (1) and (2) below: (i) relocation of
existing impervious area on a multifamily and other lot; (ii) increase in impervious
area on any lot subject to limitations on impervious area in an approved plat or plan
for reasons such as watershed protection or stormwater control measure
requirements; (iii) increase of more than 500 square feet in impervious area on a
multifamily and other lot; (iv) increase of more than 2000 square feet of Impervious
Surface area on a single family or duplex residential lot included on a preliminary or
final plat submitted for review, or on any lot utilized for recreation. For purposes of
calculating these thresholds, subject Development that is part of a Common Plan of
Development shall be assessed with other portions of such common plan that have
not previously complied with peak flow requirements.
(1) For purposes of applying peak flow requirements for the 2- and 10-year
storms, the land cover (including type and location) existing as of April 23, 1997
shall be considered the "pre -development conditions";
(2) For purposes of applying the peak flow requirement for the 1-year storm, the
land cover (including type and location) that existed as of March 9, 2001 for
land in the Falls Basin and Lower Neuse Basin, and as of March 17, 2009 for
land in the Jordan Basin shall be considered the "pre -development conditions";
(c)Requirements.
(1)Stormwater impact analysis. Development that is not exempt under
subsection (b) above shall submit a stormwater impact analysis or approved
alternative to such analysis that complies with city stormwater standards as
part of the application for site plan or subdivision plat approval, or if such is not
required, as part of submittals for construction drawings or utility permit
approval. Calculations shall be made in conformance with city stormwater
standards. No subdivision plats, site plans, utility permits, or construction
drawings shall be approved in the absence of a determination by the
stormwater division that required submissions have been made and approved.

(2) One-year storm. Development that increases the peak runoff rate from the
1-year storm from pre -development conditions shall provide stormwater
management facilities in accordance with City Stormwater Standards such
that there is no net increase in peak runoff rate. This requirement shall be
applicable in the Jordan basin only when one acre or more of land has been
cumulatively disturbed and the previously pervious portion of the property as
of March 17, 2009 will be developed to exceed 24% Impervious Surface area
(3) Two- and ten-year storms. Development that increases the peak runoff rate
from either the 2-year or the 10-year storm from pre -development conditions
may be required to provide stormwater management facilities to address the
impact, as determined in accordance with City Stormwater Standards.
One -Year Storm Peak Runoff Analysis
Five locations labeled DP#1, DP#2, DP#3, DP#4, and DP#5, were analyzed to determine
the impact of the development on peak runoff rates during the 1-year storm. Each of
the locations chosen represents the point upstream of a buffered stream channel where
SCM's will discharge in the post -development condition. Peak runoff rates were
calculated for the pre -and post -development conditions and demonstrate the runoff
rate in the stream channels will not increase in the one-year storm as a result of the
development.
Two and Ten -Year Storm Peak Runoff Analysis
There are two location where concentrated runoff will be discharged from the site in the
post -development condition, DP#1 and DP#3. Calculations are provided for DP#1 that
demonstrate the SCM provided upstream of this point will attenuate peak flows to at or
below the pre -development rate.
The second point where runoff leaves the property, DP#3, is in the channel of Martin
Branch. Martin branch has a large drainage area to this location of over 1,500 acres. To
show compliance with City of Durham requirements for the two and ten-year storms at
this location, a site -to -drainage area analysis is utilized to demonstrate that the overall
site area draining to it represents a small portion of the overall drainage area. The
portion of the site draining to Martin Branch at the analysis point compared to the total
drainage area is slightly over the highest threshold listed in the Reference Guide for
Development of 10% at 10.2%; however, the overall impervious percentage of the
development is significantly less than the proposed land use impervious percentage for
this threshold listed in the RGD of 35%, being only 27%. This analysis demonstrates the
development complies with the intent of the site -to -drainage area analysis
requirements.
All impervious surfaces in post -development are considered directly connected. The
runoff from these surfaces either drains directly to a stormwater conveyance or are
discharged to the ground surface as concentrated flow in such a manner that there will
be no appreciable volume reduction through infiltration before the runoff is ultimately
collected by the stormwater conveyance.

Water Quality
Per section, 70-739 of the City of Durham Stormwater Ordinance the project is located in
the Falls Regulatory Basin, is part of a Common plan of development, and disturbs more
than 12,000 sf since the baseline date of 7/6/2012 (Falls Basin); therefore, the project is
subject to the requirements for stormwater pollutants found in sections 70-740 and 70-
741 of the City of Durham Stormwater Ordinance.
Required Reductions for Nutrients
Sec. 70-740. Required reductions for nutrients and TSS; alternatives; calculations.
(a) Nutrient loading rate limits. Development not exempt under subsection 70-739
shall construct and implement SCMs so as to limit the post construction loading rate
of nitrogen and phosphorus from the project area to the limits set forth in Table 2
below, or shall comply with an allowed alternative as set forth in subsections (b)
through (d) below. A portion of the reduction requirements for nitrogen and
phosphorus may be met through off site measures or payments as set forth in section
70-741.
Table 2
Nutrient Export Loading Rate Limits
Project Location
Export Limit Ibs/acre/year
Nitrogen
Phosphorus
Falls Basin
2.2
0.33
Lower Neuse Basin
3.6
not required
(c) TSS Reduction. TSS reduction is applicable to Development as further described in
this subsection (c) when the following conditions are met:
• An increase in Impervious Surface area occurs as compared to what existed
as of March 17, 2009; and
• The increase in Impervious Surface area assessed in comparison to pervious
area existing as of March 17, 2009 exceeds 24%
(1) Piped areas in low density projects. Projects that do not require construction
of SCMs because their impervious percentage is less than that described in the
paragraph above must treat TSS from stormwater runoff that is conveyed in
non -vegetated conveyances, such as stormwater pipes, but excluding road
and driveway crossings.

(2)Overtreatment to address untreatable areas. Where treatment for TSS is not
reasonably practicable, as determined by the department, such as when
impervious areas include offsite transportation improvements or small
noncontiguous areas at the edge of a project, additional reductions of TSS
may be required in treatable areas, such as overtreatment in other project
areas or treatment of offsite runon.
(f)Calculations for nutrient loading and TSS removal. Pollutant loading calculations
shall be made using city stormwater standards. All increases in impervious surfaces
shall be included, including but not limited internal and off -site transportation
improvements. Approved methodologies for calculating pollutant loading shall be
maintained in writing by the public works department and shall include those
methodologies and calculations required to be used by the division of water quality
or DWQ-approved alternate methodologies.
(g)Submittals. An applicant shall submit pollutant loading calculations for the pre -
and post -development conditions as part of its application for approval of a
subdivision or site plan, utility permit, or construction drawings for a street or utility.
This project is subject to TSS removal requirements. All runoff from impervious surfaces
drains to one of the wet detention basins to receive 85% TSS removal.
On -Site Percentage Removal Requirements
Sec. 70-741. On -site treatment requirements; offsite purchase and credit options;
bacteria control.
(a) On Site Nutrient Treatment Requirements. Nitrogen and phosphorus reduction
requirements may be met, in part, through offsite management measures or the
purchase of nutrient credits. At a minimum, however, in the Falls Basin a percentage
of the required nitrogen and phosphorus reductions must be achieved through
onsite treatment in the amount shown in Table 3 below. In addition to meeting the
percentage reductions below, in the Lower Neuse Basin, nitrogen export load from
the site must not exceed 6 lbs. per acre per year for Limited Residential, and 10 lbs.
per acre per year for Multifamily and Other. (Note: offsite credit purchases do not
meet TSS removal requirements, which must be met onsite.)

Table 4
Onsite Nutrient Treatment Requirements
Project Location
Minimum Onsite Nutrient Treatment
Nitrogen
Phosphorus
Falls - General
*50% of required
reduction
*50% of required
reduction
Falls Downtown Area
Falls exceeding thresholds but
with less than 1 acre land
disturbance
Lower Neuse
*30% of required
reduction
*30% of required
reduction
No Percentage reductions
apply, but the 6/10 nitrogen
export limit described in
paragraph (a) above must
be met
*30% of required
reduction
*30% of required
reduction
Not required
*The "required reduction" is the difference between the post -development loading rate
in pounds per acre per year before treatment minus the loading rate target in pounds
per acre per year. The percentage shown in the chart above is applied to the
difference and the resulting number is the amount in pounds/acre/year that the nutrient
loading rate must be reduced onsite.
(b)Offset payments to state approved nutrient mitigation banks. Development and
redevelopment shall have the option of purchasing nutrient credits from state -
approved nutrient banks to partially offset nitrogen and/or phosphorus loads as
allowed by state law and regulation, including but not limited to 15A NCAC
02B.0235, 15A NCAC 02B.0282, and 15A NCAC 02B.0240, as they may be amended
from time to time. In the Jordan Basin, calculation of credits required shall reflect
state approved delivery factors. The number of pounds for which credits are
purchased shall be increased by five percent if the nutrient bank is not located in
the city. The following additional requirements shall apply:
(1)Location of nutrient banks. Development in the Falls Basin must use nutrient
banks located in the upper Falls portion of the Falls Basin - the portion that is
north and/or west of Highway 50.
(2)Certification of nutrient bank provider. Offset credits may only be obtained
from nutrient banks certified by the state.
(3)Utilization of NC Ecosystem Enhancement Program. Credits may also be
obtained from the NC Ecosystem Enhancement Program if such credits are

available, and if applicable state requirements regarding utilization of private
nutrient banks are first met.
(4)Certification of credits. Credits purchased pursuant to this subsection (b)
shall be verified by the state and proof of such verification that meets city
requirements shall be presented prior to approval of a final plat, or if no plat is
required, prior to issuance of the first building permit within the project, or such
earlier deadline as may be required by city stormwater standards.
The project will provide five wet detention basins, WDB#1, WDB#2, WDB#3, WDB#4, and
WDB#5, to provide on -site nutrient reduction. A level spreader with engineered filter strip
will also be installed downstream of WDB#5 to provide additional nutrient reduction. The
level spreader will receive the low flow drawdown from WDB#5's temporary pool.
Nutrient loading calculations are provided that demonstrate the proposed SCM's will
provide 50% of the required nitrogen and phosphorus reduction as required for the Falls
Basin. Any remaining loading above the required nitrogen and phosphorous loading
targets of 2.2 and 0.33 Ibs/ac/yr, respectively, will be reduced by making an offset
payment as required by NC state regulations. This meets City of Durham Requirements.
Bacteria Control
Sec. 70-741. On -site treatment requirements; offsite purchase and credit options;
bacteria control.
(d)Bacteria Removal; Control of Other Identified Stormwater Pollutants. All
Development which constructs SCMs in order to comply with this Article and which is
located in an area that is subject to a state -approved Total Maximum Daily Load for
bacteria shall be required to have at least one primary SCM for each stormwater
discharge that is rated as medium, good, high, or excellent for its ability to remove
bacteria from stormwater. Ratings shall be those that appear in the utilized version of
the NC DEQ Stormwater design manual and/or North Carolina Stormwater Control
Measure Credit Document as specified in the Reference Guide for Development or
as determined or approved by the Director. In addition, SCMs required to be
constructed under this Article must also treat any other pollutant for which a Total
Maximum Daily Load has been identified for the area within which the SCM is
located.
This project is not located in an area that is subject to a state approved total maximum
daily load for bacteria or turbidity; therefore, no bacteria or turbidity removal is required.

UDO Sec. 8.7. Watershed Protection Overlay Standards
C. Stormwater Control Requirements
Where development proposes intensity greater than the maximum authorized by
the Low Density Option, engineered stormwater controls shall be used to
control stormwater runoff from the first inch of rainfall in order to meet water quality
concerns.
The project proposes greater than 24% impervious surface; therefore, it is subject to the
stormwater control requirement. The first 1-inch of rainfall runoff from impervious
surfaces will be directed to a wet detention basin in order to receive a minimum of 85%
TSS removal.
I. Wet Detention Basins and Level Spreaders
The wet detention basins and level spreader are designed to comply with the
requirements of the archived NC BMP Manual and the City of Durham's Addendum to
that manual.
J. Diffuse Flow into Riparian Buffers
All wet detention basins provide 30% nitrogen removal and utilize pipes to convey their
outflow through the buffer to the stream channel. This complies with Option 2 of Section
8.1.6 of the City of Durham Reference Guide for Development.
K. Methodology
• Drainage basins were delineated using GIS and field surveyed topography.
• United States Geological Survey Map is the Southeast Durham Quadrangle.
• The FEMA Map associated with the site is Map 3720086000K and 3720087000K;
effective date October 19, 2018.
• Soil data to determine curve numbers in the watersheds are from the USDA Web Soil
Survey Application. Onsite soils are mostly HSB `D' with some being HSG `B'.
L. Conclusions
One, Two, and Ten-year rainfall event peak flow detention is provided at DP#1 by
WDB#1. One-year peak flow at DP#2, DP#3, DP#4, and DP#5 is provided by the wet
detention bason upstream that shares its name. Compliance with Two and Ten-year
peak flow requirements at DP#3 is demonstrated utilizing a site -to -drainage area
analysis.
The five wet detention basins and one level spreader serve to provide 50% of the
required nitrogen and phosphorous loading reduction on -site. Any remaining nitrogen
and phosphorous loading exceeding 2.2 and 0.33 Ibs/ac/yr, respectively, will be
mitigated by purchasing offset credits.
85% TSS removal will be provided in the SCM's for all on -site impervious surfaces except
for the greenway trail.

City of Durham Stormwater Site Plan Checklist

DURHAM
i
1869
CITY OF MEDICINE
CITY OF DURHAM — STORMWATER SERVICES SITE PLAN SUBMITTAL CHECKLIST
Department of Public Works
101 City Hall Plaza 1 Durham, NC 27701
919.560.4326 1 F 919.560.4316
www.durhamnc.gov
Date: 03/17/2021
ROJECT INFORMATION
Project Name:
Phase: N/A
1101 Olive Branch Road
Previous Project Name(s): N/A
PIN (s ): 0860-03-84-5286
Planning Case Number: N/A
Contact Person:
Company:
Email Address:
Matt Jones, PE
Horvath Associates, PA
[e-mail]
Phone:
Fax:
919-490-4990
INSTRUCTIONS
For each review submittal, including re -submittals, the entire Stormwater Impact Analysis (SIA) and
submittal checklist shall be submitted. Partial SIA and checklist will result in notification of an
incomplete submittal with no review performed.
Contact Stormwater Services regarding redevelopment or expansion projects for modified requirements.
The following checklist outlines submittal requirements. Initial in the space provided to indicate the
following submittal requirements have been met and supporting documentation is attached.
A. GENERAL REQUIREMENTS
Initials
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(Check One) Q INSIDE ❑OUTSIDE Watershed Protection Overlay (WPO).
Indicate the WPO(s) where the project is located:
(Check all that apply) ❑ F/J-A ❑✓ F/J-B ❑ E-A ❑ E-B ❑ M/LR-A ❑ M/LR-B
If inside WPO, notation of WPO Standards is required on plans.
MJ (Check all that apply) ❑Jordan Basin ✓❑Falls Basin ❑ Lower Neuse Basin
MJ A legible copy of the United States Geological Survey 7.5 Minute Quadrangle map is provided,
including map reference, with site boundary clearly shown and labeled. The map clearly shows
all streams.
MJ A legible copy of the published Durham County Soil Survey is provided, including map reference,
with the site boundary clearly shown and labeled. The map clearly shows all streams, soil types
and soil type boundaries.
MJ Tops of banks for the streams are shown on the plan. [Contact the North Carolina Department of
Environment and Natural Resources for stream identifications in the Neuse River Basin (Falls
and Lower Neuse Basins). Stream determinations in the Jordan Basin shall be submitted per the
Letter to Industry found on Stormwater Development Reviews' web site at New Stream Buffer
Requirements [First Revision to LTI 07-03-081 (25Auqust2011)].
All Watershed Protection Overlay, Neuse River Basin, Jordan Basin, and City riparian buffers,
measured from the tops of the stream banks, are shown on the plan.
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N/A
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The 10-foot no build setback, measured from all riparian buffers, is shown on the plan.
Diffuse flow is achieved into riparian buffers.
(Check One) QYes ❑ No Regulated floodplain located on site.
A legible copy of the effective Federal Emergency Management Agency National Flood
Insurance Program Flood Insurance Rate Map is provided. Map number, map date, and site
boundary are clearly shown and labeled. [This map is required regardless of whether floodplain
is located on the site.] The effective and/or future FEMA 100-year floodplain, with base flood
elevations (if applicable), are shown on the plan.
All applicable notes, per the Standard Notes section of the Reference Guide for Development,
have been added to the plan.
Stormwater Impact Analysis (SIA) sealed and signed by a registered North Carolina Professional
Engineer (NCPE) is provided, including narrative report and drainage calculations. Note: If a site
is exempt from stormwater requirements then a narrative advising of the exemption can be
submitted by any designer.
B. PEAK DISCHARGE RATE EVALUATION
Initials
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An introductory narrative describing pre- and post -development site conditions and site
improvement changes, is provided. Note: The baseline conditions for the 1-year event varies
based upon the regulatory basin in which the project is located.
Drainage area maps (one map for pre -development and one map for post -development) are
provided with the following items:
MJ Scale and north arrow (Note: Except in the instance of site -to -drainage area maps, the
scale of each drainage area map shall not exceed 1" = 30').
MJ Sub -basin area(s) delineated with area(s) in acres indicated.
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Analysis points clearly identified and labeled.
Segmented TR-55 time of concentration flow paths showing and labeling each segment.
Methodologies and procedures are fully described.
A site plan with contour lines or grading plan identifying pre- and post -development drainage
patterns is provided.
Pre- and post -development times of concentration, calculated by TR-55 segmented approach,
are provided.
Calculations for the pre- and post -development peak discharge rates are provided for the 1-, 2-,
10-, and 100-year, 24-hour storm using TR-55, TR-20, HEC-HMS, HEC-1 or Rational Method as
applicable. Note: The Rational Method is not accepted for the 1-year analysis, areas that drain
more than 50 acres, or watersheds that are not homogeneous.
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A Summary of Results is provided in the following format:
Site Analysis Point #
Site Condition
Storm Event (cfs)
1-year (cfs)
2-year (cfs)
10-year (cfs)
100-year (cfs)
-year (cfs)
Pre -Development
Post -Development
without Detention
Post -Development
with Detention
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Conclusions providing detailed findings are provided.
Stormwater control measure(s) (SCM[s]) are provided (indicate number of each type of SCM):
1 Level Spreader w/ Vegetative Filter Strip Stormwater Wetland
5
Wet Detention Basin Sand Filter Bioretention Grassed Swale
Restored Riparian Buffer Dry Extended Detention Basin
Permeable Pavement Green Roof Disconnected Impervious Surface
Rainwater Harvesting System
Proprietary Systems or Other
Not required (provide explanation):
The SCM(s) indicated above are required to control the following peak discharge rates:
x 1-year 2-year 10-year 100-year Other
A downstream analysis in accordance with the Reference Guide for Development is provided
with findings, or is
x Not required (provide explanation):
Detention is provided on site for all required storm events
C. POLLUTANT CONTROL RE UIREMENTS
Initials
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The project is exempt based upon cumulative land disturbance as of the applicable baseline
date.
The proposed project is X >_ 16% impervious (Falls and Jordan Basins) / >_ 24%
impervious (Lower Neuse Basin), 85% Total Suspended Solids (TSS) removal is provided for
this project, and all the impervious area as reasonably practical is treated by an SCM.
OR
The proposed project is <16% impervious (Falls and Jordan Basins) / <24%
impervious (Lower Neuse Basin), 85% Total Suspended Solids (TSS) removal for all runoff from
non -vegetated conveyances is provided for this project, and all the impervious area as
reasonably practical is treated by an SCM.
The project is low density without non -vegetated conveyances, thus TSS removal is not
required.
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SCMs for TSS removal are provided (indicate number of each type of SCM): Note: Not all of the
SCMs listed below provide 85% TSS removal as a stand-alone SCM and must be used in series
with other SCMs to achieve the minimum TSS removal of 85%.
Level Spreader w/ Vegetative Filter Strip Stormwater Wetland
5
Wet Detention Basin Sand Filter Bioretention Grassed Swale
Restored Riparian Buffer Dry Extended Detention Basin
Permeable Pavement Green Roof Disconnected Impervious Surface
Rainwater Harvesting System
Proprietary Systems or Other
Not required (provide explanation):
Hard copies of the following:
• Pre- and post -development nutrient calculations using the Jordan/Falls Lake Stormwater
Nutrient Load Accounting Tool found
at: http://portal.ncdenr.orq/web/lordanlake/implementation-guidance-archive
or http://durhamnc.gov/ich/op/pwd/storm/Pages/SWDevReview.aspx
Note: Nutrient calculations are always required regardless if the project is exempt from
treatment requirements.
• The Nutrient Reporting Form (including the Compliance Worksheet tab) per the 3/7/2013
Letter to Industry http://durhamnc.gov/ich/op/pwd/storm/Pages/LTI-SWDevReview.aspx
Pre- and post -development land use area maps that correspond to the categories used in the
Jordan/Falls Lake Stormwater Nutrient Load Accounting Tool for the nutrient calculations, to
scale no smaller than 1 inch = 100 feet. The maps shall show the map scale, north arrow, and
are to have the different land uses either hatched or shaded with areas indicated in a legend on
the maps. Note: The land use area maps are always required regardless if the project is exempt
from treatment requirements.
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N/A
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SCMs for nutrient control are provided (indicate number of each type of SCM):
5
Level Spreader w/ Vegetative Filter Strip Stormwater Wetland
Wet Detention Basin Sand Filter Bioretention Grassed Swale
Restored Riparian Buffer Dry Extended Detention Basin
Permeable Pavement Green Roof Disconnected Impervious Surface
Rainwater Harvesting System
Proprietary Systems or Other
Not required (provide explanation):
After meeting the minimum on -site treatment requirements, additional treatment and/or offsite
credit purchases, if needed, is provided by:
Additional SCMs
Nutrient Offset Payment to the North Carolina Ecosystem Enhancement Program
Nutrient Offset Payment to an Approved Nutrient Bank
Land Bank Credit Transfer (Commitments shall be made prior to October 1, 2015)
The project site is located in an area subject to a state -approved Total Maximum Daily Load
(TMDL) for bacteria. (As of April 2014, only Northeast Creek has a TMDL for bacteria).
SCMs rated as medium or high for bacterial removal are provided (indicate number of each type
of SCM):
Bioretention Area Stormwater Wetlands
Wet Detention Basin Sand Filter
Level Spreader w/ Vegetative Filter Strip Restored Riparian Buffer
Dry Extended Detention Basin Permeable Pavement
Other (specify)
X Not required (provide explanation):
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D. WATERSHED PROTECTION OVERLAY REQUIREMENTS
Initials
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85% Total Suspended Solids (TSS) removal is required for this project, and 100% of the
impervious area will be treated by an SCM. Note: Not all of the SCMs listed below provide 85%
TSS removal as a stand-alone SCM and must be used in series with other SCMs to achieve the
minimum TSS removal of 85%.
SCM for TSS removal are provided (indicate number of each type of SCM):
1 Level Spreader w/ Vegetative Filter Strip Stormwater Wetland
5 Wet Detention Basin Sand Filter Bioretention Grassed Swale
Restored Riparian Buffer Dry Extended Detention Basin
Permeable Pavement Rooftop Runoff Management
Disconnected Impervious Surface Rainwater Harvesting System
Proprietary Systems or Other
Not required (provide explanation):
E. ELECTRONIC FILE SUBMITTAL
Initials
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A compact disc (CD), DVD rom disk, or USB drive, separate from that submitted to fulfill the
Planning Department's electronic file submittal requirements, and marked "For Stormwater
Services" has been included with the submittal. An electronic file transfer protocol or other
internet cloud -based file sharing website can be used in place of the electronic media. The disc
or USB drive contains electronic copies of the following:
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Sealed SIA: entire document including narrative, data, calculations, pre- and post -
development drainage area maps, pre- and post -development land use area maps that
correspond to the categories used in the JFLSAT, and all appendices (pdf format)
Jordan/Falls Lake Stormwater Accounting Tool (Excel format)
Nutrient Reporting Form (Excel format)
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SCM Sizing Calculations

1886-WDB#1 Sizing.xls
Surface Area Calcs (85% TSS)
Matt Jones, PE
10/26/2021
1886 - 1101 Olive Branch Road
WDB#1 - Surface Area
Drainage Area to Basin = 18.89 acres
Impervious Area to Basin = 9.38 acres
Impervious Percentage = 50%
Avereage Depth (Volume/SA) = 3.00 ft
Interpolation to Determine SA/DA Ratio
Average Depth (Vol/SA) (ft)
Impervious
Lower Boundary 50%
Site % impervious 50%
Upper Boundary 50%
3.0 3.0 3.0
2.06
2.06
2.06
2.06
2.06
2.06
2.06
SA/DA =
2.06
Surface Area Required = 16,951 sf
Surface Area Provided = 30,383 sf
<- from table below
<- interpolated
<- from table below
Surface Area (SA) to Drainage Area (DA) Ratio for Permanent Pool Sizing to
Achieve 85 Percent TSS Pollutant Removal Efficiency in the Piedmont
(From NCDWQ Stormwater BMP Manual, July 2007)
Percent
Impervious
Permanent Pool Average Depth (ft)
Cover
3.0
4.0
5.0
6.0
7.0
8.0
9.0
10%
0.59
0.49
0.43
0.35
0.31
0.29
0.26
20%
0.97
0.79
0.70
0.59
0.51
0.46
0.44
30%
1.34
1.08
0.97
0.83
0.70
0.64
0.62
40%
1.73
1.43
1.25
1.05
0.90
0.82
0.77
50%
2.06
1.73
1.50
1.30
1.09
1.00
0.92
60%
2.40
2.03
1.71
1.51
1.29
1.18
1.10
70%
2.88
2.40
2.07
1.79
1.54
1.35
1.26
80%
3.36
2.78
2.38
2.10
1.86
1.60
1.42
90%
3.74
3.10
2.66
2.34
2.11
1.83
1.67

1886 - WDB#1 Sizing.xls
WQ Volume
Matt Jones, PE
10/26/2021
1886 - 1101 Olive Branch Road
WDB#1 - Water Quality Volume
Runoff Volume
Simple Method
Drainage Area (A) = 18.89 Acres
Impervious Area = 9.38 Acres
Impervious Fraction (IA) = 0.50
Rainfall Depth (RD) = 1.00 Inch
Rv= 0.50 (Rv = 0.05+0.9*IA)
Runoff Volume (V) =
34285
Normal Pool Elevation = 352.00
Temporary Pool Elevation = 354.00
Temporary Pool Volume =
Temporary Pool Surface Area =
Percentage Oversized (TPV/V) =
69925
37742
204%
cf (V = 3630*RD*Rv*A)
cf (From HydroCAD Report)
sf (From HydroCAD Report)

1886 - W DB# 1 Sizing.xls
Drawdown Orifice Sizing
Matt Jones, PE
10/26/2021
1886 - 1101 Olive Branch Road
WDB#1 - Drawdown Calculation
Water Quality Drawdown Orifice Sizing
3
Ai=
Ao=
Cd=
a=
g=
HI=
T=
37,742
30,383
0.6
0.049
32.2
2.00
in (Orifice Size)
sf (Area of pond at the beginning of drawdown)
sf (Area of pond at the orifice outlet elevation)
(Orifice Coefficient of Discharge)
sf Orifice Area (calculated)
ft/s` Acceleration of Gravity (constant)
ft (Maximum head (t=0))
4.56 days (Time for water level to fall from HI to Permanent Pool Elevation)
3.5.2 Orifice Equation
3.5.2.1 Drawdown Time Calculations for a Pond with an Orifice Outlet
A,
dh
City of Greensboro
Stormwater Management Manual
-Orifice Outlet
For the specific case where Az = Ao and Hz = 0
1
Cd*a*VZ*8*[r2*A.o* .liiz+2(Al —A0)*H /21]

1886 - WDB#2 Sizing.xls
Surface Area Calcs (85% TSS)
Matt Jones, PE
10/26/2021
1886 - 1101 Olive Branch Road
WDB#2 - Surface Area
Drainage Area to Basin = 24.59 acres
Impervious Area to Basin = 11.48 acres
Impervious Percentage = 47%
Avereage Depth (Volume/SA) = 4.00 ft
Interpolation to Determine SA/DA Ratio
Average Depth (Vol/SA) (ft)
Impervious
Lower Boundary 40%
Site % impervious 47%
Upper Boundary 50%
4.0 4.0 4.0
1.43
1.43
1.64
1.64
1.64
1.73
1.73
SA/DA =
1.64
Surface Area Required = 17,567 sf
Surface Area Provided = 19,043 sf
<- from table below
<- interpolated
<- from table below
Surface Area (SA) to Drainage Area (DA) Ratio for Permanent Pool Sizing to
Achieve 85 Percent TSS Pollutant Removal Efficiency in the Piedmont
(From NCDWQ Stormwater BMP Manual, July 2007)
Percent
Impervious
Permanent Pool Average Depth (ft)
Cover
3.0
4.0
5.0
6.0
7.0
8.0
9.0
10%
0.59
0.49
0.43
0.35
0.31
0.29
0.26
20%
0.97
0.79
0.70
0.59
0.51
0.46
0.44
30%
1.34
1.08
0.97
0.83
0.70
0.64
0.62
40%
1.73
1.43
1.25
1.05
0.90
0.82
0.77
50%
2.06
1.73
1.50
1.30
1.09
1.00
0.92
60%
2.40
2.03
1.71
1.51
1.29
1.18
1.10
70%
2.88
2.40
2.07
1.79
1.54
1.35
1.26
80%
3.36
2.78
2.38
2.10
1.86
1.60
1.42
90%
3.74
3.10
2.66
2.34
2.11
1.83
1.67

1886 - WDB#2 Sizing.xls
WQ Volume
Matt Jones, PE
10/26/2021
1886 - 1101 Olive Branch Road
WDB#2 - Water Quality Volume
Runoff Volume
Simple Method
Drainage Area (A) = 24.59 Acres
Impervious Area = 11.48 Acres
Impervious Fraction (IA) = 0.47
Rainfall Depth (RD) = 1.00 Inch
Rv= 0.47 (Rv = 0.05+0.9*IA)
Runoff Volume (V) =
41953
Normal Pool Elevation = 297.00
Temporary Pool Elevation = 299.20
Temporary Pool Volume =
Temporary Pool Surface Area =
Percentage Oversized (TPV/V) =
49575
25106
118%
cf (V = 3630*RD*Rv*A)
cf (From HydroCAD Report)
sf (From HydroCAD Report)

1886 - WDB#2 Sizing.xls
Drawdown Orifice Sizing
Matt Jones, PE
10/26/2021
1886 - 1101 Olive Branch Road
WDB#2 - Drawdown Calculation
Water Quality Drawdown Orifice Sizing
24.34
11.48
3
Ai=
Ao=
Cd=
a=
g=
HI=
T=
25,106
19,043
0.6
0.049
32.2
2.20
in (Orifice Size)
sf (Area of pond at the beginning of drawdown)
sf (Area of pond at the orifice outlet elevation)
(Orifice Coefficient of Discharge)
sf Orifice Area (calculated)
ft/s` Acceleration of Gravity (constant)
ft (Maximum head (t=0))
3.07 days (Time for water level to fall from HI to Permanent Pool Elevation)
3.5.2 Orifice Equation
3.5.2.1 Drawdown Time Calculations for a Pond with an Orifice Outlet
A,
dh
City of Greensboro
Stormwater Management Manual
-Orifice Outlet
For the specific case where Az = Ao and Hz = 0
1
Cd*a*VZ*8*[r2*A.o* .liiz+2(Al —A0)*H /21]

1886 - WDB#3 Sizing.xls
Surface Area Calcs (85% TSS)
Matt Jones, PE
12/9/2021
1886 - 1101 Olive Branch Road
WDB#3 - Surface Area
Drainage Area to Basin = 9.67 acres
Impervious Area to Basin = 4.53 acres
Impervious Percentage = 47%
Avereage Depth (Volume/SA) = 3.00 ft
Interpolation to Determine SA/DA Ratio
Average Depth (Vol/SA) (ft)
Impervious
Lower Boundary 40%
Site % impervious 47%
Upper Boundary 50%
3.0 3.0 3.0
1.73
1.73
1.96
1.96
1.96
2.06
2.06
SA/DA =
1.96
Surface Area Required = 8,256 sf
Surface Area Provided = 10,443 sf
<- from table below
<- interpolated
<- from table below
Surface Area (SA) to Drainage Area (DA) Ratio for Permanent Pool Sizing to
Achieve 85 Percent TSS Pollutant Removal Efficiency in the Piedmont
(From NCDWQ Stormwater BMP Manual, July 2007)
Percent
Impervious
Permanent Pool Average Depth (ft)
Cover
3.0
4.0
5.0
6.0
7.0
8.0
9.0
10%
0.59
0.49
0.43
0.35
0.31
0.29
0.26
20%
0.97
0.79
0.70
0.59
0.51
0.46
0.44
30%
1.34
1.08
0.97
0.83
0.70
0.64
0.62
40%
1.73
1.43
1.25
1.05
0.90
0.82
0.77
50%
2.06
1.73
1.50
1.30
1.09
1.00
0.92
60%
2.40
2.03
1.71
1.51
1.29
1.18
1.10
70%
2.88
2.40
2.07
1.79
1.54
1.35
1.26
80%
3.36
2.78
2.38
2.10
1.86
1.60
1.42
90%
3.74
3.10
2.66
2.34
2.11
1.83
1.67

1886 - WDB#3 Sizing.xls
WQ Volume
Matt Jones, PE
12/9/2021
1886 - 1101 Olive Branch Road
WDB#3 - Water Quality Volume
Runoff Volume
Simple Method
Drainage Area (A) = 9.67 Acres
Impervious Area = 4.53 Acres
Impervious Fraction (IA) = 0.47
Rainfall Depth (RD) = 1.00 Inch
Rv= 0.47 (Rv = 0.05+0.9*IA)
Runoff Volume (V) =
16498
Normal Pool Elevation = 284.00
Temporary Pool Elevation = 286.00
Temporary Pool Volume =
Temporary Pool Surface Area =
Percentage Oversized (TPV/V) =
26391
14905
160%
cf (V = 3630*RD*Rv*A)
cf (From HydroCAD Report)
sf (From HydroCAD Report)

1886 - WDB#3 Sizing.xls
Drawdown Orifice Sizing
Matt Jones, PE
12/9/2021
1886 - 1101 Olive Branch Road
WDB#3 - Drawdown Calculation
Water Quality Drawdown Orifice Sizing
2
Ai=
Ao=
Cd=
a=
g=
HI=
T=
14,905
10,443
0.6
0.022
32.2
2.00
in (Orifice Size)
sf (Area of pond at the beginning of drawdown)
sf (Area of pond at the orifice outlet elevation)
(Orifice Coefficient of Discharge)
sf Orifice Area (calculated)
ft/s` Acceleration of Gravity (constant)
ft (Maximum head (t=0))
3.69 days (Time for water level to fall from HI to Permanent Pool Elevation)
3.5.2 Orifice Equation
3.5.2.1 Drawdown Time Calculations for a Pond with an Orifice Outlet
A,
dh
City of Greensboro
Stormwater Management Manual
-Orifice Outlet
For the specific case where Az = Ao and Hz = 0
1
Cd*a*VZ*8*[r2*A.o* .liiz+2(Al —A0)*H /21]

1886 - WDB#4 Sizing.xls
Surface Area Calcs (85% TSS)
Matt Jones, PE
12/9/2021
1886 - 1101 Olive Branch Road
WDB#4 - Surface Area
Drainage Area to Basin = 18.50 acres
Impervious Area to Basin = 9.23 acres
Impervious Percentage = 50%
Avereage Depth (Volume/SA) = 3.00 ft
Interpolation to Determine SA/DA Ratio
Average Depth (Vol/SA) (ft)
Impervious
Lower Boundary 50%
Site % impervious 50%
Upper Boundary 50%
3.0 3.0 3.0
2.06
2.06
2.06
2.06
2.06
2.06
2.06
SA/DA =
2.06
Surface Area Required = 16,601 sf
Surface Area Provided = 24,451 sf
<- from table below
<- interpolated
<- from table below
Surface Area (SA) to Drainage Area (DA) Ratio for Permanent Pool Sizing to
Achieve 85 Percent TSS Pollutant Removal Efficiency in the Piedmont
(From NCDWQ Stormwater BMP Manual, July 2007)
Percent
Impervious
Permanent Pool Average Depth (ft)
Cover
3.0
4.0
5.0
6.0
7.0
8.0
9.0
10%
0.59
0.49
0.43
0.35
0.31
0.29
0.26
20%
0.97
0.79
0.70
0.59
0.51
0.46
0.44
30%
1.34
1.08
0.97
0.83
0.70
0.64
0.62
40%
1.73
1.43
1.25
1.05
0.90
0.82
0.77
50%
2.06
1.73
1.50
1.30
1.09
1.00
0.92
60%
2.40
2.03
1.71
1.51
1.29
1.18
1.10
70%
2.88
2.40
2.07
1.79
1.54
1.35
1.26
80%
3.36
2.78
2.38
2.10
1.86
1.60
1.42
90%
3.74
3.10
2.66
2.34
2.11
1.83
1.67

1886 - WDB#4 Sizing.xls
WQ Volume
Matt Jones, PE
12/9/2021
1886 - 1101 Olive Branch Road
WDB#4 - Water Quality Volume
Runoff Volume
Simple Method
Drainage Area (A) = 18.50 Acres
Impervious Area = 9.23 Acres
Impervious Fraction (IA) = 0.50
Rainfall Depth (RD) = 1.00 Inch
Rv= 0.50 (Rv = 0.05+0.9*IA)
Runoff Volume (V) =
33578
Normal Pool Elevation = 302.00
Temporary Pool Elevation = 303.60
Temporary Pool Volume =
Temporary Pool Surface Area =
Percentage Oversized (TPV/V) =
45015
30316
134%
cf (V = 3630*RD*Rv*A)
cf (From HydroCAD Report)
sf (From HydroCAD Report)

1886 - WDB#4 Sizing.xls
Drawdown Orifice Sizing
Matt Jones, PE
12/9/2021
1886 - 1101 Olive Branch Road
WDB#4 - Drawdown Calculation
Water Quality Drawdown Orifice Sizing
3
Ai=
Ao=
Cd=
a=
g=
Hi=
T=
30,316
24,451
0.6
0.049
32.2
1.60
in (Orifice Size)
sf (Area of pond at the beginning of drawdown)
sf (Area of pond at the orifice outlet elevation)
(Orifice Coefficient of Discharge)
sf Orifice Area (calculated)
ft/s` Acceleration of Gravity (constant)
ft (Maximum head (t=0))
3.28 days (Time for water level to fall from HI to Permanent Pool Elevation)
3.5.2 Orifice Equation
3.5.2.1 Drawdown Time Calculations for a Pond with an Orifice Outlet
A,
dh
City of Greensboro
Stormwater Management Manual
-Orifice Outlet
For the specific case where Az = Ao and Hz = 0
1
Cd*a*VZ*8*[r2*A.o* .liiz+2(Al —A0)*H /21]

1886 - WDB#5 Sizing.xls
Surface Area Calcs (85% TSS)
Matt Jones, PE
12/9/2021
1886 - 1101 Olive Branch Road
WDB#5 - Surface Area
Drainage Area to Basin = 29.53 acres
Impervious Area to Basin = 14.97 acres
Impervious Percentage = 51%
Avereage Depth (Volume/SA) = 3.00 ft
Interpolation to Determine SA/DA Ratio
Average Depth (Vol/SA) (ft)
Impervious
Lower Boundary 50%
Site % impervious 51%
Upper Boundary 60%
3.0 3.0 3.0
2.06
2.06
2.09
2.09
2.09
2.40
2.40
SA/DA =
2.09
Surface Area Required = 26,884 sf
Surface Area Provided = 28,583 sf
<- from table below
<- interpolated
<- from table below
Surface Area (SA) to Drainage Area (DA) Ratio for Permanent Pool Sizing to
Achieve 85 Percent TSS Pollutant Removal Efficiency in the Piedmont
(From NCDWQ Stormwater BMP Manual, July 2007)
Percent
Impervious
Permanent Pool Average Depth (ft)
Cover
3.0
4.0
5.0
6.0
7.0
8.0
9.0
10%
0.59
0.49
0.43
0.35
0.31
0.29
0.26
20%
0.97
0.79
0.70
0.59
0.51
0.46
0.44
30%
1.34
1.08
0.97
0.83
0.70
0.64
0.62
40%
1.73
1.43
1.25
1.05
0.90
0.82
0.77
50%
2.06
1.73
1.50
1.30
1.09
1.00
0.92
60%
2.40
2.03
1.71
1.51
1.29
1.18
1.10
70%
2.88
2.40
2.07
1.79
1.54
1.35
1.26
80%
3.36
2.78
2.38
2.10
1.86
1.60
1.42
90%
3.74
3.10
2.66
2.34
2.11
1.83
1.67

1886 - WDB#5 Sizing.xls
WQ Volume
Matt Jones, PE
12/9/2021
1886 - 1101 Olive Branch Road
WDB#5 - Water Quality Volume
Runoff Volume
Simple Method
Drainage Area (A) = 29.53 Acres
Impervious Area = 14.97 Acres
Impervious Fraction (IA) = 0.51
Rainfall Depth (RD) = 1.00 Inch
Rv= 0.51 (Rv = 0.05+0.9*IA)
Runoff Volume (V) =
54669
Normal Pool Elevation = 302.00
Temporary Pool Elevation = 303.80
Temporary Pool Volume =
Temporary Pool Surface Area =
Percentage Oversized (TPV/V) =
59255
35475
108%
cf (V = 3630*RD*Rv*A)
cf (From HydroCAD Report)
sf (From HydroCAD Report)

1886 - WDB#5 Sizing.xls
Drawdown Orifice Sizing
Matt Jones, PE
12/9/2021
1886 - 1101 Olive Branch Road
WDB#5 - Drawdown Calculation
Water Quality Drawdown Orifice Sizing
3
Ai=
Ao=
Cd=
a=
g=
HI=
T=
35,475
28,583
0.6
0.049
32.2
1.80
in (Orifice Size)
sf (Area of pond at the beginning of drawdown)
sf (Area of pond at the orifice outlet elevation)
(Orifice Coefficient of Discharge)
sf Orifice Area (calculated)
ft/s` Acceleration of Gravity (constant)
ft (Maximum head (t=0))
4.06 days (Time for water level to fall from HI to Permanent Pool Elevation)
3.5.2 Orifice Equation
3.5.2.1 Drawdown Time Calculations for a Pond with an Orifice Outlet
A,
dh
City of Greensboro
Stormwater Management Manual
-Orifice Outlet
For the specific case where Az = Ao and Hz = 0
1
Cd*a*VZ*8*[r2*A.o* .liiz+2(Al —A0)*H /21]

Nutrient Loading Calculations

DURHAM
I I
1869
crc.a.ex.+E
CITY OF DURHAM Neuse, Falls Lake and Jordan Lake Developer Nutrient Reporting Form
Not required if the project is exempt from pollutant standards per Section 70-739 of the City Code
Please complete and submit the following information to the City of Durham Stormwater Services to
characterize your project and assess the need to purchase nutrient offsets. See the
City of Durham Stormwater Standards. For nutrient offset information, see nutrient offset info
PROJECT INFORMATION
Applicant Name :
Pulte Homes
Prepared by :
Matt Jones, PE
Project Name (& Previous name, if applicable):
1101 Olive Branch Road
Site Plan #:
D2100088
Project Address (if available): Street: City/Town: County:
1101 Olive Branch Road
Date: (mo/d/yr)
5/28/2021
Project
Locat'n:
Lat: (dec. degrees)
35.960541
Long: (dec. degrees)
-768651.000000
PIN/PID #s:
0860-03-84-5286
Is this Redevelopment?
° Yes ° No Development Type (Please check all that apply)
Impervious Cover (%) Pre -Construction: ❑
0 ❑
Commercial ❑ Duplex Residential
Industrial o Single -Family Residential
Institutional ❑ Multi -Family Residential
Mixed Use
Impervious Cover (%) Post -Construction: ❑
28 ❑
WATERSHED INFORMATION (See Jordan map or Falls Lake map)
o Upper Falls Basin, 12-digit Watershed ID:
❑ Neuse/Outside of Falls Basin, 03020201
❑ Jordan Lake (Upper New Hope) 6-digit Small
Watershed ID:
030202010304
03020201
Jordan Lake Delivery Factors (%)
Nitrogen
Phosphorus
Site Factor:
Site Factor:
Neuse/Falls Lake Delivery Factors: There are no delivery factors, so the Delivery Factor = 1.
DURHAM STORMWATER PERFORMANCE STANDARDS FOR DEVELOPMENT COMPLIANCE ALTERNATIVE
Nutrient loading limits and on -site treatment minimum (Sections 70-740(a) and Sections 70-741(a))
Off -site treatment threshold (%): N:
50 P:
50
Required on -site reduction achieved?
N:
YES P: YES
NUTRIENT OFFSET REQUEST (Must meet the offsite thresholds — see above)
Nitrogen Loading / Offset Needs (For the Jordan, Falls, and Neuse/Outside of Falls Watershed areas)
(A)
(B)
(C)
(D)
(E)
(F)
(G)
(H)
(I) (Where
Applicable)
(J)
Untreated
Loading
Rate
(Ibs/ac/yr)
Treated
Loading
Rate
(Ibs/ac/yr)
Load Rate
Target
(Ibs/ac/yr)
Reduction
Needed
(Ibs/ac/yr)
(from Compl.
Worksheet)
Project Size
(square feet)
Offset
Duration
(yrs)
Site Delivery
Factor
State Buy Down
Amount Delivered
(Ibs)
D* E* F* G
Additional
5% if bank
not in City
limits (Ibs)
Total Delivered
(Ibs)
H + I
4.33
3.21
2.20
1.01
7,819,623
30
1.00
5439.27
271.96
5711.23
Phosphorus Loading / Offset Needs (For the Jordan and Falls Watershed areas)
(A)
(B)
(C)
(D)
(E)
(F)
(G)
(H)
(I) (Where
Applicable)
(J)
Untreated
Loading
Rate
(Ibs/ac/yr)
Treated
Loading
Rate
(Ibs/ac/yr)
Load Rate
Target
(Ibs/ac/yr)
Reduction
Needed
(Ibs/ac/yr)
(from Compl.
Worksheet)
Project Size
(square feet)
Offset
Duration
(yrs)
Site Delivery
Factor
State Buy Down
Amount Delivered
(Ibs)
D* E* F* G
Additional
5% if bank
not in City
limits (Ibs)
Total Delivered
(Ibs)
H + I
0.73
0.49
0.33
0.16
7,819,623
30
1.00
861.67
43.08
904.75
Responsible Professional Engineer's Name:
Matt Jones
PE #:
39170
Staff Name:
Staff e-mail
Phone #:
January 9, 2018 Version

Watershed (Select from Menu)
1
Falls Lake Basin
Jordan Lake Basin
Lower Neuse Basin
COMPLIANCE WORKSHEET
Note that if a nutrient bank is used to buy offset credits
in order to achieve compliance with the alternative
selected below, the bank must be located in the same
watershed as the project site.
Compliance Alternative (Pick one alternative, see descriptions and calculations below)
1
0
0
0
Nutrient loading limits and on -site treatment minimum (Sections 70-740(a) and Sections 70-741(a))
Alternative percentage reduction option for Redevelopment that increases impervious area (Section 70-
740(b))
Alternative percentage reduction option for Redevelopment that does not increase impervious area
(Section 70-740(c))
Alternative for low impact development in Falls Basin.
If the project is Exempt from Stormwater Pollutant standards (Section 70-739), nutrient calculation:
Project Area Disturbance (Fill in yellow cell below)
5,358,000 square feet
123.003 acres
TABLE 1 THRESHOLDS FOR APPLICATION OF STORMWATER
POLLUTANT REQUIREMENTS
Project Location
Land Disturbance
Limited Residential
Multifamily & Other
Jordan Basin
1 acre
0.5 acres
Falls Basin
0.5 acres
12,000 square feet
Lower Neuse Basin
1 acre
0.5 acres
Note: Thresholds are based upon land disturbance since the
applicable basin Baseline date.
The Project is Located Outside the Downtown Area (select from menu list)
Per Section 70-736, Downtown Area means the Downtown Tier, Compact Neighborhoods,
and Suburban Transit Zones as shown on the Durham Comprehensive Land Use Plan most
recently approved by the Durham City Council.
The Project Type is Limited Residential (select from menu list)
Per Section 70-736,
Limited Residential means single family and duplex residential and recreational development.
Multifamily and Other Development means development not included in Limited Resdiential, and
includes but is not limited to multifamily and townhomes, and office, industrial, institutional (including local
government institutional), and commercial development.
Other key definitions from Section 70-736:
Development means Land Disturbance which increases impervious surface on a property, or
alters its location, or results in an increase in runoff from a property or a decrease in infiltration
of precipitation into the soil. It includes both existing development and new development. It
does not include agriculture, mining, or forestry activities.
Redevelopment means Development on a site where structures or impervious surface
already exists. It is a category of new development.
March 30, 2017 Version

Nutrient Loading Limits and On -Site Treatment Minimum
ORDINANCE REQUIREMENTS
Sec. 70-740.
(a) Nutrient Loading Rate Limits. Development not exempt under subsection 70-739 shall
construct and implement SCMs so as to limit the post construction loading rate of nitrogen
and phosphorus from the project area to the limits set forth in Table 2 below, or shall
comply with an allowed alternative as set forth in (b) through (d) below. A portion of the
reduction requirements for nitrogen and phosphorus may be met through off site
measures or payments as set forth in 70-741.
TABLE 2 NUTRIENT EXPORT LOADING RATE LIMITS
Project Location
Export Limit Ibs/acre/year
Nitrogen
Phosphorus
Jordan Basin
2.2
0.82
Falls Basin
2.2
0.33
Lower Neuse Basin
3.6
not required
Sec. 70-741
(a) On site nutrient treatment requirements. Nitrogen and phosphorus reduction
requirements may be met, in part, through offsite management measures or the
purchase of nutrient credits. At a minimum, however, in the Jordan and Falls Basins a
percentage of the required nitrogen and phosphorus reductions must be achieved through
onsite treatment, in the amount shown in Table 4 below. In addition to meeting the
percentage reductions below, in the Jordan and Lower Neuse Basins, nitrogen export
load from the site must not exceed 6 Ibs. per acre per year for Limited Residential, and
and 10 Ibs per acre per year for Multifamily and Other.
(Note: offsite credit purchases do not meet TSS removal requirements, which must be
met onsite.)
TABLE 4 ONSITE NUTRIENT TREATMENT REQUIREMENTS
Project
Minimum Onsite Nutrient Treatment
Nitrogen
Phosphorus
Jordan -General
*40% of required
reduction
*40% of required
reduction
Falls -General
*50% of required
reduction
*50% of required
reduction
Falls and Jordan within
Downtown Area
*30% of required
reduction
*30% of required
reduction
March 30, 2017 Version

Falls and Jordan exceeding
thresholds but with less than 1
acre land disturbance
*30% of required
reduction
*30% of required
reduction
Lower Neuse
No percentage
reductions apply, but
the 6/10 nitrogen
export limit described
in paragraph (a)
above must be met
No percentage
reductions apply, but
the 6/10 nitrogen
export limit described
in paragraph (a)
above must be met
*The "required reduction" is the difference between the post development loading in
pounds per acre per year multiplied by the site area in acres before treatment minus the
loading target, in pounds per acre per year multiplied by the acres. The percentage shown in
the chart above is applied to that difference and the resulting number is the amount in
pounds/year of nutrient reduction that must be achieved onsite.
CALCULATIONS - ENTER VALUES IN YELLOW CELLS
Nitrogen
Post Loading Rate
Untreated (Ibs/ac/yr)
Post Loading Rate
Treated (Ibs/ac/yr)
Load Rate Target
(Ibs/ac/yr)
Reduction Needed
(Ibs/ac/yr)
4.33
3.21
2.2
1.01
Phosphorus
Post Loading Rate
Untreated (Ibs/ac/yr)
Post Loading Rate
Treated (Ibs/ac/yr)
Load Rate Target
(Ibs/ac/yr)
Reduction Needed
(Ibs/ac/yr)
0.73
0.49
0.33
0.16
ONSITE CALCULATIONS - ENTER VALUE IN YELLOW CELLS BASED ON TABLE 4
Onsite Reduction
Required (%)
Required Onsite Reduction Achieved?
Nitrogen
Phosphorus
50
YES
YES
In the Jordan and Lower Neuse Basins, the nitrogen export loading rate from the
site does not exceed 6 Ib/ac/yr for Limited Residential, or 10 Ib/ac/yr for Multifamily
and Other.
N/A
March 30, 2017 Version

Project Information
Project Name:
1101 Olive Branch Road
Submission Date:
10/26/2021
Project Area (ft2):
7,819,623 ft2
Disturbed Area (ft2):
5,358,000 ft2
Development Land Use Type:
Single Family Residential
Development Activity Type:
Development - New
Designated Downtown Area?
no
Project Location/Address:
1101 Olive Branch Road
County:
Durham
Local Jurisdiction:
Durham
Project Latitude Coordinates:
35.960541 N
Project Longitude Coordinates:
-78.768573 W
Precipitation Station:
Durham
Physiographic Region:
Triassic Basin
Nutrient Management Watershed:
Falls Lake
Subwatershed:
Falls - Upper
Phosphorus Delivery Zone:
Falls - Upper
Nitrogen Delivery Zone:
Falls - Upper
Project Designer and Contact Phone
Number / Email:
Matt Jones, PE / 919-490-4990 / matt.jones@horvi
Part of Common Development Plan?
no
Project Owner Type:
Private
Project Description:
Townhomes and Single -Family

Project Area Land Cover Characteristics
PROJECT AREA LAND COVERS
TN TP
EMC EMC
(mg/L) (mg/L)
Pre- Post -
Project I Project
Area (ft2) Area (ft2)
Roof
1.18
0.11
902,242
Roadway
1.64
0.34
560,000
Parking/Driveway/Sidewalk
1.42
0.18
695,558
Protected Forest
0.97
0.03
7,819,623
2,310,400
Other Pervious/Landscaping
2.48
1.07
3,238,120
CUSTOM LAND COVER 1
CUSTOM LAND COVER 2
CUSTOM LAND COVER 3
LAND TAKEN UP BY SCM
1.18
0.11
113,303
LAND COVER AREA CHECK
Net Change of Land Covers (ft2):
Total Project Area Entered (ft2):
Total Pre -Project Calculated Area (ft2):
Total Post -Project Calculated Area (ft2):
5,509,223
7,819,623
7,819,623
7,819,623
Equations Used and Project Area Calculations
S I M P L E METHOD Stormwater Runoff Volume Generated, V
Runoff Coefficient R V = Pj* Rv * (P/12) *A
R„ = 0.05 + (0.009 *I) where A = drainage area (ft2)
where I = percent impervious (%) Pj = fraction of rain events with runoff
Average Annual Pollutant Load, L P = average annual rainfall depth (in)
L= (Pj*R„*(P/12))*(C*A*2.72)
where C = event mean concentration (mg/L)
Pre -Project: Post -Project:
A = 179.5138 ac
P= 47.81 in.
V = 1401961 ft3
1= 0%
Rv = 0.05
Pi = 0.9
CTN = 0.97 mg/L
CTP = 0.03 mg/L
LTN = 84.92 Ib/yr
LTP = 2.63 Ib/yr
A = 179.5138 ac
P = 47.81 in.
V = 8751521 ft3
I = 29%
Rv = 0.31
Pi = 0.9
CTN = 1.42 mg/L
CTP = 0.24 mg/L
LTN = 776.83 Ib/yr
LTP = 130.60 Ib/yr

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Proiect Summa
Durham
Private
0
Falls - Upper
Falls - Upper
%00Z
2.20
0Mi
01
m
576.80
4.76
a
oo
M
LID
000
oo
r-I
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oo
r-I
Nitrogen Delivery Factor (%):
Nitrogen Loading Rate Target (Ib/ac/yr):
Nitrogen Load Target at Site (Ib/yr):
Nitrogen Load Leaving Site w/SCMs (Ib/yr):
N Offsite Buy -Down Threshold Loading Rate
Total N Load Reduction Needed (Ib/yr):
N Load Treatment Balance at Site (Ib/yr):
N Load Treatment Balance at Lake (Ib/yr):
7,819,623 ft2 179.5138 acres
5,358,000 ftL 123.0028 acres
Local Jurisdiction:
Owner Type:
Designated Downtown Area?
Subwatershed:
Nitrogen Delivery Zone:
Durham
Single Family Residential
Development - New
Falls Lake
Falls - Upper
%00Z
rn M
O
59.24
N
oo
000
N
O
M
N
co
Q1
N
co
Q1
oo
N
Phosphorus Delivery Factor (%):
Phosphorus Loading Rate Target (Ib/ac/yr):
Phosphorus Load Target at Site (Ib/yr):
Phosphorus Load Leaving Site w/SCMs (Ib/yr):
P Offsite Buy -Down Threshold Loading Rate (Ib/ac/yr):
Total P Load Reduction Needed (Ib/yr):
P Load Treatment Balance at Site (Ib/yr):
P Load Treatment Balance at Lake (Ib/yr):
Project Name:
Project Area (ft2):
Disturbed Area (ft2):
County:
Development Land Use Type:
Development Activity Type:
Nutrient Management Watershed:
Phosphorus Delivery Zone:
Disturbed Area.
4-0 MS
U
aj
G1 4,
•RI
o a) cdi
o
a v
~ a
o v
a
V1
2
N
without SCMs
Conditions
ort Summar
Nutrient Ex
0.0%
0.0%
630,326
58.54
N
O
m
O
N
•c-I
r�1
41
O
0
00
N
Ln
o
r-I
O
in
6,906,266
1.20
in
NI
00
ri
in
5.25
0.17
73.02
0.74
0
O
N
0
l0
NIenu1
r1
LcP1
,
Ln
438%
1.22
576.80
N
al
rO-I
O
88.23
01
CS
O
N
27.6%
8,751,521
524%
d-
r1
m
wO
Is.
n
4.33
815%
N
O
130.60
N
Q
0.0%
0.0%
l0
01
0
r�
o
O
0.97
84.92
0.47
o
0
0.03
CA
t0
N
ey
O
O
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 (Ib/yr)
Total Nitrogen Loading Rate (Ib/ac/yr)
Total Nitrogen % Change (relative to pre-D)
Total Phosphorus EMC (mg/L)
Total Phosphorus Load Leaving Site (Ib/yr)
Total Phosphorus Loading Rate (Ib/ac/yr)

0
O
l0
N
m
O
m
00
0
O
Total Phosphorus % Change (relative to pre-D)
SCM/Catchment Summary
TP Reduction (%)
TN Reduction
0
4
J
ao
E
4J
0
a
J
dCo
C
0
z
H
v
E
0
0
.4J
w0
v
CC
SCM ID and Type
c''
00
l0
m
Oin in
00
l0
m
0.00%
0.00%
ON.
O
Cr;
m
ON.
O
m
m
0.00%
0.00%
Or-i
r'I
00
m
Or-i
r'I
00
m
0.00%
0.00%
O
N.
I,:
m
O
N.
I,:
m
0.00%
0.00%
O
r'I
00
m
O
NI
4
m
0
O
6
0.00%
0.00%
0.00%
0.00%
0.00%
0
ill
O
N
0
Ifl
O
N
0.00%
0.00%
0
d'
00
r-I
0
d'
00
r-I
0.00%
0.00%
0
1.0
O
N
0
1.0
O
N
0.00%
0.00%
0
m
ul
N
0
m
u'1
N
0.00%
0.00%
43.53%
0
O
al
r-I
0
N
O
m
0.00%
0.00%
0.00%
0.00%
0.00%
CO
O
0.81
0.00
0.00
0.74
0.74
0.00
O
O
0.75
0.75
O
O
O
O
kD
O
k0
O
O
O
0.00
N.
O
N
O
0.72
0.00
0.00
0.00
0.00
O
O
O
N
Lo
O
N
Qo
O
O
O
O
O
O
5.72
5.72
O
O
O
O
O
O
5.64
5.64
O
O
O
O
O
O
M
M
ul
M
M
ul
O
O
O
O
O
O
r1
r-I
et:
5.89
r1
r-I
et:
0
0
O
0
0
O
0
0
O
0
0
O
0
0
O
O
0.17
O
O
O
O
,
a—Ia—I
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,
O
O
O
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0.17
0.17
OO,,OO
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r-I
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l0
N
r-.
l0
N
r-.
O
O
O
O
O
O
Lfl
N
r-.
Lfl
N
r-.
O
O
O
O
O
O
l0
N
r-.
l0
N
r-.
O
O
O
O
O
O
Lfl
N
r-.
Lfl
N
r-.
O
O
O
O
O
O
1.07
Lfl
N
r-.
1.07
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
8.44%
8.44%
0.00%
0.00%
8.44%
8.44%
0.00%
0.00%
8.44%
8.44%
0.00%
0.00%
00
00
00
l0
r-I
00
00
1.0
r-I
0.00%
0.00%
0
N
al
4
N
8.44%
18.00%
0.00%
0.00%
0.00%
0.00%
0.00%
Catchment 1
101: Wet Pond per MDC
102: NA
Z
m
0
r-1
Catchment 2
201: Wet Pond per MDC
202: NA
203: NA
Catchment 3
301: Wet Pond per MDC
302: NA
Z
m
0
m
Catchment 4
401: NA
402: NA
403: NA
Catchment 5
Z
e.1
0
Li-)
502: NA
503: NA
Catchment 6
Z
e.1
0
l0
Z
N
0
l0
603: NA

Peak Runoff Analysis

SIA - SUMMARY OF RESULTS.xls Matt Jones, PE
Summary of Results
1886 - 1101 Olive Branch Road
Runoff Analysis - Summary of Results
DP#1
Site Condition
Storm Event
1-Year (cfs)
2-year (cfs)
10-year (cfs)
Pre -Development
8.86
12.13
22.15
Post -Development without
Detention
60.79
75.46
116.99
Post -Development with
Detention
2.82
3.48
5.41
Post -Development with
Detention Percent Increase
-68.17%
-71.31%
-75.58%
DP#2
Site Condition
Storm Event
1-Year (cfs)
2-year (cfs)
10-year (cfs)
Pre -Development
5.07
N/A
N/A
Post -Development without
Detention
78.87
N/A
N/A
Post -Development with
Detention
4,06
N/A
N/A
Post -Development with
Detention Percent Increase
-19.92%
N/A
N/A
DP#3
Site Condition
Storm Event
1-Year (cfs)
2-year (cfs)
10-year (cfs)
Pre -Development
2.85
N/A*
N/A*
Post -Development without
Detention
28.86
N/A*
N/A*
Post -Development with
Detention
2.53
N/A*
N/A*
Post -Development with
Detention Percent Increase
-11.23%
N/A*
N/A*
DP#4
Site Condition
Storm Event
1-Year (cfs)
2-year (cfs)
10-year (cfs)
Pre -Development
1.62
N/A
N/A
Post -Development without
Detention
53.02
N/A
N/A
Post -Development with
Detention
1.53
N/A
N/A
Post -Development with
Detention Percent Increase
-5.56%
N/A
N/A
DP#5
Site Condition
Storm Event
1-Year (cfs)
2-year (cfs)
10-year (cfs)
Pre -Development
3.91
N/A
N/A
Post -Development without
Detention
91.71
N/A
N/A
Post -Development with
Detention
2.46
N/A
N/A
Post -Development with
Detention Percent Increase
-37.08%
N/A
N/A
*Site to Drainage Area Analysis provided for 2- and 10-year storms

D P#2
Subcat DP#2
Subcat DP #1
Subcat
Reach
Subcat DP#3
Subcat DP#4
Subcat DP#5
Routing Diagram for SIA PRE
Prepared by {enter your company name here}, Printed 8/5/2021
HydroCAD® 10.10-5a s/n 03736 ©2020 HydroCAD Software Solutions LLC

SIA PRE Type 11 24-hr 1-Year Rainfall=3.00"
Prepared by {enter your company name here} Printed 8/5/2021
HydroCAD® 10.10-5a s/n 03736 © 2020 HydroCAD Software Solutions LLC Page 2
Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points
Runoff by SCS TR-20 method, UH=SCS, Weighted-Q
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment DP #1: Subcat DP #1
Subcatchment DP#2: Subcat DP#2
Subcatchment DP#3: Subcat DP#3
Runoff Area=6.69 ac 10.01% Impervious Runoff Depth> 1.17"
Flow Length=804' Tc=16.8 min CN=WQ Runoff=8.86 cfs 0.654 af
Runoff Area=3.50 ac 0.00% Impervious Runoff Depth>1.07"
Flow Length=1,108' Tc=12.8 min CN=77 Runoff=5.07 cfs 0.311 af
Runoff Area=1.85 ac 0.00% Impervious Runoff Depth>1.07"
Flow Length=753' Tc=11.1 min CN=77 Runoff=2.85 cfs 0.165 of
Subcatchment DP#4: Subcat DP#4 Runoff Area=6.23 ac 0.00% Impervious Runoff Depth>0.34"
Flow Length=1,173' Tc=17.3 min CN=WQ Runoff=1.62 cfs 0.179 af
Subcatchment DP#5: Subcat DP#5 Runoff Area=9.22 ac 0.00% Impervious Runoff Depth>0.45"
Flow Length=1,667' Tc=16.2 min CN=WQ Runoff=3.91 cfs 0.349 af

SIA PRE Type 11 24-hr 1-Year Rainfall=3.00"
Prepared by {enter your company name here} Printed 8/5/2021
HydroCAD® 10.10-5a s/n 03736 © 2020 HydroCAD Software Solutions LLC Page 3
Summary for Subcatchment DP #1: Subcat DP #1
Runoff = 8.86 cfs @ 12.10 hrs, Volume=
0.654 af, Depth> 1.17"
Runoff by SCS TR-20 method, UH=SCS, Weighted-Q, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs
Type II 24-hr 1-Year Rainfall=3.00"
Area (ac) CN Description
0.65 55 Forest, good, HSG B
5.37 77 Forest, good, HSG D
0.03 98 Roof, good, HSG D
0.64 100 Water Surface, good, HSG D
6.69 Weighted Average
6.02 75 89.99% Pervious Area
0.67 100 10.01% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
14.5 75 0.0270 0.09 Sheet Flow,
Woods: Light underbrush n= 0.400 P2= 3.50"
1.2 307 0.0680 4.20 Shallow Concentrated Flow,
Unpaved Kv= 16.1 fps
0.4 241 9.83 Lake or Reservoir,
Mean Depth= 3.00'
0.7 181 0.0280 4.48 8.95 Channel Flow,
Area= 2.0 sf Perim= 4.0' r= 0.50' n= 0.035
16.8 804 Total
Summary for Subcatchment DP#2: Subcat DP#2
Runoff = 5.07 cfs @ 12.06 hrs, Volume=
0.311 af, Depth> 1.07"
Runoff by SCS TR-20 method, UH=SCS, Weighted-Q, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs
Type II 24-hr 1-Year Rainfall=3.00"
Area (ac) CN Description
3.50 77 Forest, good, HSG D
3.50 77 100.00% Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
9.4 75 0.0800 0.13 Sheet Flow,
Woods: Light underbrush n= 0.400 P2= 3.50"
1.0 356 0.1400 6.02 Shallow Concentrated Flow,
Unpaved Kv= 16.1 fps
2.4 677 0.0300 4.63 9.27 Channel Flow,
Area= 2.0 sf Perim= 4.0' r= 0.50' n= 0.035
12.8 1,108 Total

SIA PRE Type 11 24-hr 1-Year Rainfall=3.00"
Prepared by {enter your company name here} Printed 8/5/2021
HydroCAD® 10.10-5a s/n 03736 © 2020 HydroCAD Software Solutions LLC Page 4
Summary for Subcatchment DP#3: Subcat DP#3
Runoff = 2.85 cfs @ 12.04 hrs, Volume=
0.165 af, Depth> 1.07"
Runoff by SCS TR-20 method, UH=SCS, Weighted-Q, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs
Type II 24-hr 1-Year Rainfall=3.00"
Area (ac) CN Description
1.85 77 Forest, good, HSG D
1.85 77 100.00% Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
8.2 75 0.1100 0.15 Sheet Flow,
Woods: Light underbrush n= 0.400 P2= 3.50"
2.9 678 0.0590 3.91 Shallow Concentrated Flow,
Unpaved Kv= 16.1 fps
11.1 753 Total
Summary for Subcatchment DP#4: Subcat DP#4
Runoff = 1.62 cfs @ 12.13 hrs, Volume=
0.179 af, Depth> 0.34"
Runoff by SCS TR-20 method, UH=SCS, Weighted-Q, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs
Type II 24-hr 1-Year Rainfall=3.00"
Area (ac) CN Description
5.14 55 Forest, good, HSG B
1.09 77 Forest, good, HSG D
6.23 Weighted Average
6.23 59 100.00% Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
12.4 75 0.0400 0.10 Sheet Flow,
Woods: Light underbrush n= 0.400 P2= 3.50"
2.0 570 0.0880 4.78 Shallow Concentrated Flow,
Unpaved Kv= 16.1 fps
2.9 528 0.0130 3.05 6.10 Channel Flow,
Area= 2.0 sf Perim= 4.0' r= 0.50' n= 0.035
17.3 1,173 Total
Summary for Subcatchment DP#5: Subcat DP#5
Runoff = 3.91 cfs @ 12.11 hrs, Volume=
0.349 af, Depth> 0.45"
Runoff by SCS TR-20 method, UH=SCS, Weighted-Q, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs
Type II 24-hr 1-Year Rainfall=3.00"

SIA PRE Type 11 24-hr 1-Year Rainfall=3.00"
Prepared by {enter your company name here} Printed 8/5/2021
HydroCAD® 10.10-5a s/n 03736 © 2020 HydroCAD Software Solutions LLC Page 5
Area (ac) CN Description
6.46 55 Forest, good, HSG B
2.77 77 Forest, good, HSG D
9.22 Weighted Average
9.22 62 100.00% Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
9.3 75 0.0810 0.13 Sheet Flow,
Woods: Light underbrush n= 0.400 P2= 3.50"
2.8 838 0.0950 4.96 Shallow Concentrated Flow,
Unpaved Kv= 16.1 fps
4.1 754 0.0130 3.05 6.10 Channel Flow,
Area= 2.0 sf Perim= 4.0' r= 0.50' n= 0.035
16.2 1,667 Total

Subcat
Reach
<DP#i>
Subcat DP #1
Routing Diagram for SIA PRE
Prepared by {enter your company name here}, Printed 8/5/2021
HydroCAD® 10.10-5a s/n 03736 ©2020 HydroCAD Software Solutions LLC

SIA PRE Type 11 24-hr 2-Year Rainfall=3.57"
Prepared by {enter your company name here} Printed 8/5/2021
HydroCAD® 10.10-5a s/n 03736 © 2020 HydroCAD Software Solutions LLC Page 2
Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points
Runoff by SCS TR-20 method, UH=SCS, Weighted-Q
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment DP #1: Subcat DP #1 Runoff Area=6.69 ac 10.01% Impervious Runoff Depth>1.58"
Flow Length=804' Tc=16.8 min CN=WQ Runoff=12.13 cfs 0.878 af
Total Runoff Area = 6.69 ac Runoff Volume = 0.878 af Average Runoff Depth = 1.58"
89.99% Pervious = 6.02 ac 10.01% Impervious = 0.67 ac

SIA PRE Type 11 24-hr 2-Year Rainfall=3.57"
Prepared by {enter your company name here} Printed 8/5/2021
HydroCAD® 10.10-5a s/n 03736 © 2020 HydroCAD Software Solutions LLC Page 3
Summary for Subcatchment DP #1: Subcat DP #1
Runoff = 12.13 cfs @ 12.10 hrs, Volume=
0.878 af, Depth> 1.58"
Runoff by SCS TR-20 method, UH=SCS, Weighted-Q, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs
Type II 24-hr 2-Year Rainfall=3.57"
Area (ac) CN Description
0.65 55 Forest, good, HSG B
5.37 77 Forest, good, HSG D
0.03 98 Roof, good, HSG D
0.64 100 Water Surface, good, HSG D
6.69 Weighted Average
6.02 75 89.99% Pervious Area
0.67 100 10.01% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
14.5 75 0.0270 0.09 Sheet Flow,
Woods: Light underbrush n= 0.400 P2= 3.50"
1.2 307 0.0680 4.20 Shallow Concentrated Flow,
Unpaved Kv= 16.1 fps
0.4 241 9.83 Lake or Reservoir,
Mean Depth= 3.00'
0.7 181 0.0280 4.48 8.95 Channel Flow,
Area= 2.0 sf Perim= 4.0' r= 0.50' n= 0.035
16.8 804 Total

SIA PRE Type 11 24-hr 10-Year Rainfall=5.15"
Prepared by {enter your company name here} Printed 8/5/2021
HydroCAD® 10.10-5a s/n 03736 © 2020 HydroCAD Software Solutions LLC Page 4
Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points
Runoff by SCS TR-20 method, UH=SCS, Weighted-Q
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment DP #1: Subcat DP #1 Runoff Area=6.69 ac 10.01% Impervious Runoff Depth>2.81"
Flow Length=804' Tc=16.8 min CN=WQ Runoff=22.15 cfs 1.568 af
Total Runoff Area = 6.69 ac Runoff Volume = 1.568 af Average Runoff Depth = 2.81"
89.99% Pervious = 6.02 ac 10.01% Impervious = 0.67 ac

SIA PRE Type 11 24-hr 10-Year Rainfall=5.15"
Prepared by {enter your company name here} Printed 8/5/2021
HydroCAD® 10.10-5a s/n 03736 © 2020 HydroCAD Software Solutions LLC Page 5
Summary for Subcatchment DP #1: Subcat DP #1
Runoff = 22.15 cfs © 12.09 hrs, Volume=
1.568 af, Depth> 2.81"
Runoff by SCS TR-20 method, UH=SCS, Weighted-Q, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs
Type II 24-hr 10-Year Rainfall=5.15"
Area (ac) CN Description
0.65 55 Forest, good, HSG B
5.37 77 Forest, good, HSG D
0.03 98 Roof, good, HSG D
0.64 100 Water Surface, good, HSG D
6.69 Weighted Average
6.02 75 89.99% Pervious Area
0.67 100 10.01% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
14.5 75 0.0270 0.09 Sheet Flow,
Woods: Light underbrush n= 0.400 P2= 3.50"
1.2 307 0.0680 4.20 Shallow Concentrated Flow,
Unpaved Kv= 16.1 fps
0.4 241 9.83 Lake or Reservoir,
Mean Depth= 3.00'
0.7 181 0.0280 4.48 8.95 Channel Flow,
Area= 2.0 sf Perim= 4.0' r= 0.50' n= 0.035
16.8 804 Total

D P4
CDP#9
Subcat DP#1
Subcat
<WDB#>
Subcat WDB #3 WDB#3
<DP#2>
Subcat DP#2
WDB#2
Subcat WDB #2
WDB#1
Reach
(A/D13#1)
Subcat WDB #1
DP#3
4
DP#4
DP#5
<WDB#>
Subcat WDB #4
WDB#4
CDP#4)
Subcat DP#4
CDP#5)
Subcat DP#5
WDB#5
CWDB #5)
Subcat WDB #5
Routing Diagram for 1886 SIA POST
Prepared by {enter your company name here}, Printed 12/9/2021
HydroCAD® 10.10-6a s/n 03736 ©2020 HydroCAD Software Solutions LLC

1886 SIA POST Type 11 24-hr 1-Year Rainfall=3.00"
Prepared by {enter your company name here} Printed 12/9/2021
HydroCAD© 10.10-6a s/n 03736 © 2020 HydroCAD Software Solutions LLC Page 2
Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points
Runoff by SCS TR-20 method, UH=SCS, Weighted-Q
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
SubcatchmentDP#1: Subcat DP#1 Runoff Area=0.54 ac 0.00% Impervious Runoff Depth>0.41"
Tc=5.0 min CN=WQ Runoff=0.31 cfs 0.019 af
SubcatchmentDP#2: Subcat DP#2 Runoff Area=1.89 ac 0.00% Impervious Runoff Depth>1.10"
Flow Length=196' Slope=0.0930 '/' Tc=9.2 min CN=WQ Runoff=3.24 cfs 0.174 af
Subcatchment DP#4: Su bcat DP#4 Runoff Area=4.04 ac 0.00% Impervious Runoff Depth>0.29"
Flow Length=960' Tc=10.9 min CN=WQ Runoff=0.93 cfs 0.096 af
Subcatchment DP#5: Su bcat DP#5 Runoff Area=2.80 ac 0.00% Impervious Runoff Depth>0.29"
Flow Length=603' Tc=13.0 min CN=WQ Runoff=0.62 cfs 0.069 af
SubcatchmentWDB #1: SubcatWDB #1 Runoff Area=18.89 ac 53.36% Impervious Runoff Depth>2.07"
Tc=5.0 min CN=WQ Runoff=62.87 cfs 3.252 af
SubcatchmentWDB #2: SubcatWDB #2 Runoff Area=24.59 ac 48.47% Impervious Runoff Depth>1.99"
Tc=5.0 min CN=WQ Runoff=79.44 cfs 4.075 af
SubcatchmentWDB #3: SubcatWDB #3 Runoff Area=9.67 ac 49.33% Impervious Runoff Depth>1.91"
Tc=5.0 min CN=WQ Runoff=29.52 cfs 1.538 af
SubcatchmentWDB #4: SubcatWDB #4 Runoff Area=18.50 ac 52.97% Impervious Runoff Depth>1.86"
Tc=5.0 min CN=WQ Runoff=53.68 cfs 2.862 af
SubcatchmentWDB #5: Subcat WDB #5 Runoff Area=29.53 ac 52.93% Impervious Runoff Depth>1.99"
Tc=5.0 min CN=WQ Runoff=93.85 cfs 4.893 af
Pond 6P: WDB#1 Peak Elev=354.48' Storage=88,181 cf Inflow=62.87 cfs 3.252 af
Outflow=2.79 cfs 2.041 af
Pond 7P: WDB#2 Peak EIev=302.09' Storage=133,228 cf Inflow=79.44 cfs 4.075 af
Outflow=1.06 cfs 1.121 af
Pond 8P: WDB#3 Peak EIev=285.93' Storage=25,353 cf Inflow=29.52 cfs 1.538 af
Outflow=2.53 cfs 1.535 af
Pond 9P: WDB#4 Peak EIev=305.11' Storage=93,512 cf Inflow=53.68 cfs 2.862 af
Outflow=0.76 cfs 0.801 af
Pond 10P: WDB#5 Peak EIev=306.08' Storage=146,657 cf Inflow=93.85 cfs 4.893 af
Outflow=2.19 cfs 2.136 af
Link 1: DP#1 Inflow=2.82 cfs 2.060 af
Primary=2.82 cfs 2.060 af
Link 2: DP#2 Inflow=4.06 cfs 1.295 af
Primary=4.06 cfs 1.295 af

1886 SIA POST Type 11 24-hr 1-Year Rainfall=3.00"
Prepared by {enter your company name here} Printed 12/9/2021
HydroCAD® 10.10-6a s/n 03736 © 2020 HydroCAD Software Solutions LLC Page 3
Link 3: DP#3
Link 4: DP#4
Link 5: DP#5
Inflow=2.53 cfs 1.535 af
Primary=2.53 cfs 1.535 af
Inflow=1.53 cfs 0.897 af
Primary=1.53 cfs 0.897 af
Inflow=2.46 cfs 2.204 af
Primary=2.46 cfs 2.204 af
Total Runoff Area = 110.46 ac Runoff Volume = 16.978 af Average Runoff Depth = 1.84"
52.74% Pervious = 58.26 ac 47.26% Impervious = 52.20 ac

1886 SIA POST Type 11 24-hr 1-Year Rainfall=3.00"
Prepared by {enter your company name here} Printed 12/9/2021
HydroCAD® 10.10-6a s/n 03736 © 2020 HydroCAD Software Solutions LLC Page 4
Summary for Subcatchment DP#1: Subcat DP#1
Runoff = 0.31 cfs @ 11.99 hrs, Volume=
Routed to Link 1 : DP#1
0.019 af, Depth> 0.41"
Runoff by SCS TR-20 method, UH=SCS, Weighted-Q, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs
Type II 24-hr 1-Year Rainfall=3.00"
Area (ac) CN Description
0.51 61 Open, good, HSG B
0.03 80 Open, good, HSG D
0.54 Weighted Average
0.54 62 100.00% Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
0.34�
0.32�
z
o.z8�
0.26�
0.24,"
0.22
, 0.2 -
0.18�
3
0
LL
0.14�
0.12�
0.1
0.08,"
0.061
0.041
0.02�
Subcatchment DP#1: Subcat DP#1
Hydrograph
+
0.31 cfs
L
Type 11 2 1ir
1-Year- Rai n-f II 3 00"- -
Runoff Area-0.54 ac
Rijn-qff VV Iume='�0.O19 of -
Runoff Depth!0.4i"
Tc=i5.0xnt
cN=1NQ -
r
L
0 1 2 3 4 5 6 7 8 9 10 11 12 13
Time (hours)
14
15
16
17
18
19
20
21
22
23
24
• Runoff

1886 SIA POST Type 11 24-hr 1-Year Rainfall=3.00"
Prepared by {enter your company name here} Printed 12/9/2021
HydroCAD® 10.10-6a s/n 03736 © 2020 HydroCAD Software Solutions LLC Page 5
Summary for Subcatchment DP#2: Subcat DP#2
Runoff = 3.24 cfs @ 12.01 hrs, Volume=
Routed to Link 2 : DP#2
0.174 af, Depth> 1.10"
Runoff by SCS TR-20 method, UH=SCS, Weighted-Q, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs
Type II 24-hr 1-Year Rainfall=3.00"
Area (ac) CN Description
1.51 77 Forest, good, HSG D
0.38 80 Open, good, HSG D
1.89 Weighted Average
1.89 78 100.00% Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
8.8 75 0.0930 0.14 Sheet Flow,
Woods: Light underbrush n= 0.400 P2= 3.50"
0.4 121 0.0930 4.91 Shallow Concentrated Flow,
Unpaved Kv= 16.1 fps
9.2 196 Total
3—'
2 -'
0
Subcatchment DP#2: Subcat DP#2
Hydrograph
Type -u-24yhr
1-Year Rainfall=3.00"
Runoff Aroa=1 89 ac
Runoff VojIueie=O.174
Runoff Depth>
FIoW Length^1
$lope=Q.0930 '1'
tc=9.2 rnin
CNTWQ
1.10"
96'
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Time (hours)

1886 SIA POST Type 11 24-hr 1-Year Rainfall=3.00"
Prepared by {enter your company name here} Printed 12/9/2021
HydroCAD® 10.10-6a s/n 03736 © 2020 HydroCAD Software Solutions LLC Page 6
Summary for Subcatchment DP#4: Subcat DP#4
Runoff = 0.93 cfs @ 12.07 hrs, Volume=
Routed to Link 4 : DP#4
0.096 af, Depth> 0.29"
Runoff by SCS TR-20 method, UH=SCS, Weighted-Q, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs
Type II 24-hr 1-Year Rainfall=3.00"
Area (ac) CN Description
1.84 55 Forest, good, HSG B
2.20 61 Open, good, HSG B
4.04 Weighted Average
4.04 58 100.00% Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
6.7 75 0.0670 0.19 Sheet Flow,
Grass: Dense n= 0.240 P2= 3.50"
1.3 357 0.0840 4.67 Shallow Concentrated Flow,
Unpaved Kv= 16.1 fps
2.9 528 0.0130 3.05 6.10 Channel Flow,
Area= 2.0 sf Perim= 4.0' r= 0.50' n= 0.035
10.9 960 Total
0
0
Subcatchment DP#4: Subcat DP#4
Hydrograph
type II 24 hr,
1-Year Ra nfal l=3.00"
Runoff Aroa=4 04 ac
Ruiioff Voluime=O.096
Runoff Depth>0.29'
Flo* Length=960'
Tc=10.9 min
N=WQ
0 �l��l������,
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14
Time (hours)
a
15 16 17 18 19 20 21 22 23 24

1886 SIA POST Type 11 24-hr 1-Year Rainfall=3.00"
Prepared by {enter your company name here} Printed 12/9/2021
HydroCAD® 10.10-6a s/n 03736 © 2020 HydroCAD Software Solutions LLC Page 7
Summary for Subcatchment DP#5: Subcat DP#5
Runoff = 0.62 cfs @ 12.09 hrs, Volume=
Routed to Link 5 : DP#5
0.069 af, Depth> 0.29"
Runoff by SCS TR-20 method, UH=SCS, Weighted-Q, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs
Type II 24-hr 1-Year Rainfall=3.00"
Area (ac) CN Description
1.93 55 Forest, good, HSG B
0.09 77 Forest, good, HSG D
0.70 61 Open, good, HSG B
0.08 80 Open, good, HSG D
2.80 Weighted Average
2.80 58 100.00% Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
10.1 75 0.0670 0.12 Sheet Flow,
Woods: Light underbrush n= 0.400 P2= 3.50"
2.9 528 0.0130 3.05 6.10 Channel Flow,
Area= 2.0 sf Perim= 4.0' r= 0.50' n= 0.035
13.0 603 Total
0.65�
0.55�
0.5
0.45�
• 0.35�
• =
LT_ 0.3J
0.25�
0.05
Subcatchment DP#5: Subcat DP#5
Hydrograph
0.62 cfs
type ll 4.hr
1-Year Rainfall=i00"
Runoff Area=2.80 ac
Runoff 069 a
Runoff ©eptlr>0.29��-
Flow 1Le;ngth=603'- - -
Tc=1$.0min
4N=Q
9 10 11 12 13 14
Time (hours)
L
L
i
T
15 16 17 18 19 20 21 22 23 24
• Runoff

1886 SIA POST Type 11 24-hr 1-Year Rainfall=3.00"
Prepared by {enter your company name here} Printed 12/9/2021
HydroCAD® 10.10-6a s/n 03736 © 2020 HydroCAD Software Solutions LLC Page 8
Summary for Subcatchment WDB #1: Subcat WDB #1
Runoff = 62.87 cfs @ 11.95 hrs, Volume= 3.252 af, Depth> 2.07"
Routed to Pond 6P : WDB#1
Runoff by SCS TR-20 method, UH=SCS, Weighted-Q, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs
Type II 24-hr 1-Year Rainfall=3.00"
Area (ac) CN Description
0.03 61 Open, good, HSG B
8.78 80 Open, good, HSG D
0.08 98 Roadway, good, HSG B
2.95 98 Roadway, good, HSG D
2.69 98 Roof, good, HSG D
0.70 100 SCM, good, HSG D
0.03 98 Sidewalk, good, HSG B
3.63 98 Sidewalk, good, HSG D
18.89 Weighted Average
8.81 80 46.64% Pervious Area
10.08 98 53.36% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
0
0
LL
5.0 Direct Entry,
70,
65J
60:
55:
50-
45-
40-
35-
30�
25
20
15-
10-
Subcatchment WDB #1: Subcat WDB #1
Hydrograph
r
62.87 cfs
r
+--+--+-_+
F r
r r T T
Type I-124-hr
1 TYear Rair faIIT3.100"
Rwnbff Arrea=1889 aP
r r r
Rungffl Vglyme='13.252o Ru-noff Deptk>2-O7”� -
TcT5.0 ruin
r
tN=WQ
r r
0 Kra. ...... i� iZ i i
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Time (hours)
■ Runoff

1886 SIA POST Type 11 24-hr 1-Year Rainfall=3.00"
Prepared by {enter your company name here} Printed 12/9/2021
HydroCAD® 10.10-6a s/n 03736 © 2020 HydroCAD Software Solutions LLC Page 9
Summary for Subcatchment WDB #2: Subcat WDB #2
Runoff = 79.44 cfs @ 11.95 hrs, Volume= 4.075 af, Depth> 1.99"
Routed to Pond 7P : WDB#2
Runoff by SCS TR-20 method, UH=SCS, Weighted-Q, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs
Type II 24-hr 1-Year Rainfall=3.00"
Area (ac) CN Description
12.67 80 Open, good, HSG D
2.55 98 Roadway, good, HSG D
5.53 98 Roof, good, HSG D
0.44 100 SCM, good, HSG D
3.40 98 Sidewalk, good, HSG D
24.59 Weighted Average
12.67 80 51.53% Pervious Area
11.92 98 48.47% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
85-'
80-
75
70
65�
60�
55
ai 50�
3 45
.2 401
351
301
25-
201
15�
10�
5L
Subcatchment WDB #2: Subcat WDB #2
Hydrograph
r
4-
L
79.44 cfs
y
r
4,
Typ H;24hr
tt 1zYear_ Rainfalha.O0" _
R rrbff-Arrea=24ZS a�
nOff'-V-lµme=4.O7_5 a -
Ri noff Depth 1.99
r
0 1 2 3
6
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Time (hours)
• Runoff

1886 SIA POST Type 11 24-hr 1-Year Rainfall=3.00"
Prepared by {enter your company name here} Printed 12/9/2021
HydroCAD® 10.10-6a s/n 03736 © 2020 HydroCAD Software Solutions LLC Page 10
Summary for Subcatchment WDB #3: Subcat WDB #3
Runoff = 29.52 cfs @ 11.95 hrs, Volume= 1.538 af, Depth> 1.91"
Routed to Pond 8P : WDB#3
Runoff by SCS TR-20 method, UH=SCS, Weighted-Q, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs
Type II 24-hr 1-Year Rainfall=3.00"
Area (ac) CN Description
1.03 61 Open, good, HSG B
3.87 80 Open, good, HSG D
0.26 98 Roadway, good, HSG B
1.20 98 Roadway, good, HSG D
0.23 98 Roof, good, HSG B
1.32 98 Roof, good, HSG D
0.24 100 SCM, good, HSG D
0.48 98 Sidewalk, good, HSG B
1.04 98 Sidewalk, good, HSG D
9.67 Weighted Average
4.90 76 50.67% Pervious Area
4.77 98 49.33% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
32�
30�
28
26�
24�
22-
107-
8-
6�
4-
2-
Subcatchment WDB #3: Subcat WDB #3
Hydrograph
+ -
-+
29.52 cfs
L
L
L
0 Yl�fr/�f/SSfr/Sf/rFi 1
0 1 2 3 4
r
L
L
Ty pe11 24=hr -
1..Year
RainfaIIT3.00"
T Rtthoff Ara.-916- ae -
LJnOff`YQIum,e=1.$38-af
Off
L L H
Depth>1_91"
Tc .O
i
L L L
yl ICN= 11/
L L L
L L
+ + + + L
L L L L L L
,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, ,,,,,,,,,
8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Time (hours)
• Runoff

1886 SIA POST Type 11 24-hr 1-Year Rainfall=3.00"
Prepared by {enter your company name here} Printed 12/9/2021
HydroCAD® 10.10-6a s/n 03736 © 2020 HydroCAD Software Solutions LLC Page 11
Summary for Subcatchment WDB #4: Subcat WDB #4
Runoff = 53.68 cfs @ 11.95 hrs, Volume= 2.862 af, Depth> 1.86"
Routed to Pond 9P : WDB#4
Runoff by SCS TR-20 method, UH=SCS, Weighted-Q, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs
Type II 24-hr 1-Year Rainfall=3.00"
Area (ac) CN Description
4.25 61 Open, good, HSG B
4.45 80 Open, good, HSG D
1.01 98 Roadway, good, HSG B
1.04 98 Roadway, good, HSG D
2.50 98 Roof, good, HSG B
2.08 98 Roof, good, HSG D
0.29 100 SCM, good, HSG B
0.28 100 SCM, good, HSG D
1.20 98 Sidewalk, good, HSG B
1.40 98 Sidewalk, good, HSG D
18.50 Weighted Average
8.70 71 47.03% Pervious Area
9.80 98 52.97% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
60�
55�
50:
45—
30:
o =
LT_ 251-
20:
151-
10—
Subcatchment WDB #4: Subcat WDB #4
Hydrograph
L
▪ -r
53.68 cfs
Y r r
Type-H- 24-hi -
1 Yea-r- Rai i all43.(A"
-- -- Runoff -Me =1-8 5Gat--
RungffrVpluine=2.$6 �#
1--kuinaff Deptk>1.86"� -
4-
✓
0 1 2 3
4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Time (hours)
• Runoff

1886 SIA POST Type 11 24-hr 1-Year Rainfall=3.00"
Prepared by {enter your company name here} Printed 12/9/2021
HydroCAD® 10.10-6a s/n 03736 © 2020 HydroCAD Software Solutions LLC Page 12
Summary for Subcatchment WDB #5: Subcat WDB #5
Runoff = 93.85 cfs @ 11.95 hrs, Volume= 4.893 af, Depth> 1.99"
Routed to Pond 10P : WDB#5
Runoff by SCS TR-20 method, UH=SCS, Weighted-Q, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs
Type II 24-hr 1-Year Rainfall=3.00"
Area (ac) CN Description
0.08 77 Forest, good, HSG D
2.29 61 Open, good, HSG B
11.53 80 Open, good, HSG D
1.13 98 Roadway, good, HSG B
2.64 98 Roadway, good, HSG D
1.00 98 Roof, good, HSG B
5.37 98 Roof, good, HSG D
0.66 100 SCM, good, HSG D
0.89 98 Sidewalk, good, HSG B
3.94 98 Sidewalk, good, HSG D
29.53 Weighted Average
13.90 77 47.07% Pervious Area
15.63 98 52.93% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
Subcatchment WDB #5: Subcat WDB #5
Hydrograph
105-'T
100"
95
90" L
85"+
80' fi
75"
70
65"
y 60
▪ 55"�k
c 50"�
LL 45'
40
35
30' L
25
20� k
15'�
10_
T
T r
93.85 cfs
4- 1- 1-
+ r +
r 1-
T
L
1
1- 1-
+ r +
r r
LL L
1- 1-
+ r I-
T r r
+
✓ r T
✓ r
Type IF 24=hir -
1-Year Rainfal l=*.-00E` -
+ + r I I + +
Winciff Al!ea=2953 at -
Run4-
V41tna;a4.89 At -
ku,noff Depth> 99" -
Tc5.0CR=nif
0{(�}
II II
/ 4'
1 1 1
I + - - +
I -+--+
T
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Time (hours)
• Runoff

1886 SIA POST
Prepared by {enter your company name here}
HydroCAD® 10.10-6a s/n 03736 © 2020 HydroCAD Software Solutions LLC
Type 11 24-hr 1-Year Rainfall=3.00"
Printed 12/9/2021
Page 13
Inflow Area =
Inflow =
Outflow =
Primary =
Summary for Pond 6P: WDB#1
18.89 ac, 53.36% Impervious, Inflow Depth > 2.07" for 1-Year event
62.87 cfs @ 11.95 hrs, Volume= 3.252 af
2.79 cfs @ 13.18 hrs, Volume= 2.041 af, Atten= 96%, Lag= 73.6 min
2.79 cfs @ 13.18 hrs, Volume= 2.041 af
Routed to Link 1 : DP#1
Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs
Peak Elev= 354.48' @ 13.18 hrs Surf.Area= 38,923 sf Storage= 88,181 cf
Plug -Flow detention time= 337.9 min calculated for 2.037 af (63% of inflow)
Center -of -Mass det. time= 227.8 min (1,003.5 - 775.8 )
Volume Invert Avail.Storage Storage Description
#1
Elevation
(feet)
352.00
352.50
362.00
352.00'
Surf.Area
(sq-ft)
30,383
34,023
57,578
451,206 cf
Device Routing Invert
Custom Stage Data (Prismatic)Listed below (Recalc)
I nc. Store
(cubic -feet)
0
16,102
435,105
Outlet Devices
Cum.Store
(cubic -feet)
0
16,102
451,206
#1 Primary 347.00'
#2 Device 1
#3 Device 1
352.00'
353.20'
36.0" Round Culvert
L= 50.0' CPP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 347.00' / 346.50' S= 0.0100 '/' Cc= 0.900
n= 0.013, Flow Area= 7.07 sf
3.0" Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads
12.0" W x 6.0" H Vert. Orifice/Grate C= 0.600
Limited to weir flow at low heads
Primary OutFlow Max=2.80 cfs @ 13.18 hrs HW=354.48' (Free Discharge)
4-1=Culvert (Passes 2.80 cfs of 83.20 cfs potential flow)
12=Orifice/Grate (Orifice Controls 0.36 cfs @ 7.38 fps)
3=Orifice/Grate (Orifice Controls 2.43 cfs @ 4.87 fps)

1886 SIA POST Type 11 24-hr 1-Year Rainfall=3.00"
Prepared by {enter your company name here} Printed 12/9/2021
HydroCAD® 10.10-6a s/n 03736 © 2020 HydroCAD Software Solutions LLC Page 14
70-1
65▪ 'I
::t::
I
45J 'r
m 40-- 1
u =
35-
0
30�
25� i
151 ▪ �r
10L"
5�
L L
▪ 1-1
▪ L L
I I
-11
Pond 6P: WDB#1
Hydrograph
I I L
I
r
Storane=88y'E811-cf -
I I
I i I
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Time (hours)
• Inflow
• Primary

1886 SIA POST
Prepared by {enter your company name here}
HydroCAD® 10.10-6a s/n 03736 © 2020 HydroCAD Software Solutions LLC
Type 11 24-hr 1-Year Rainfall=3.00"
Printed 12/9/2021
Page 15
Inflow Area =
Inflow =
Outflow =
Primary =
Summary for Pond 7P: WDB#2
24.59 ac, 48.47% Impervious, Inflow Depth > 1.99" for 1-Year event
79.44 cfs @ 11.95 hrs, Volume= 4.075 af
1.06 cfs @ 18.62 hrs, Volume= 1.121 af, Atten= 99%, Lag= 399.8 min
1.06 cfs @ 18.62 hrs, Volume= 1.121 af
Routed to Link 2 : DP#2
Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs
Peak Elev= 302.09' @ 18.62 hrs Surf.Area= 31,498 sf Storage= 133,228 cf
Plug -Flow detention time= 439.2 min calculated for 1.118 af (27% of inflow)
Center -of -Mass det. time= 263.8 min (1,044.2 - 780.4 )
Volume Invert Avail.Storage Storage Description
#1
Elevation
(feet)
297.00
297.50
305.00
297.00'
Surf.Area
(sq-ft)
19,043
22,080
37,470
233,593 cf
Device Routing Invert
Custom Stage Data (Prismatic)Listed below (Recalc)
Inc.Store
(cubic -feet)
0
10,281
223,313
Outlet Devices
Cum.Store
(cubic -feet)
0
10,281
233,593
#1 Primary 294.00'
#2 Device 1
#3 Device 1
297.00'
298.80'
36.0" Round Culvert
L= 100.0' RCP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 294.00' / 293.00' S= 0.0100 '/' Cc= 0.900
n= 0.013, Flow Area= 7.07 sf
3.0" Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads
3.0" W x 3.0" H Vert. Orifice/Grate C= 0.600
Limited to weir flow at low heads
Primary OutFlow Max=1.06 cfs @ 18.62 hrs HW=302.09' (Free Discharge)
4-1=Culvert (Passes 1.06 cfs of 87.37 cfs potential flow)
12=Orifice/Grate (Orifice Controls 0.53 cfs @ 10.73 fps)
3=Orifice/Grate (Orifice Controls 0.54 cfs @ 8.56 fps)

1886 SIA POST Type 11 24-hr 1-Year Rainfall=3.00"
Prepared by {enter your company name here} Printed 12/9/2021
HydroCAD® 10.10-6a s/n 03736 © 2020 HydroCAD Software Solutions LLC Page 16
85'
80
75� r
70-
60�
55�
_ r
• 50�
r
.2 • 40�
35-
3O-
20� ,r
15/
10-
rr
✓ rr
✓ r r
+ --+--r
4 4 r
1 1 r
1 1 r
✓
r
r
✓
Pond 7P: WDB#2
Hydrograph
79.44 cfs
-Inflow Acme=24 9 a -
r r r r r
▪ r Y r
I_ -Sto-r ge:13
r
r
r
r T r
r r
r
22S+af -
1- I-
L L
L L
✓ r
✓ r
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Time (hours)
• Inflow
• Primary

1886 SIA POST
Prepared by {enter your company name here}
HydroCAD® 10.10-6a s/n 03736 © 2020 HydroCAD Software Solutions LLC
Type 11 24-hr 1-Year Rainfall=3.00"
Printed 12/9/2021
Page 17
Inflow Area =
Inflow =
Outflow =
Primary =
Summary for Pond 8P: WDB#3
9.67 ac, 49.33% Impervious, Inflow Depth > 1.91" for 1-Year event
29.52 cfs @ 11.95 hrs, Volume= 1.538 af
2.53 cfs @ 12.47 hrs, Volume= 1.535 af, Atten= 91%, Lag= 30.7 min
2.53 cfs @ 12.47 hrs, Volume= 1.535 af
Routed to Link 3 : DP#3
Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs
Peak Elev= 285.93' @ 12.47 hrs Surf.Area= 14,798 sf Storage= 25,353 cf
Plug -Flow detention time= 77.9 min calculated for 1.532 af (100% of inflow)
Center -of -Mass det. time= 76.4 min (854.4 - 777.9 )
Volume Invert Avail.Storage Storage Description
#1
Elevation
(feet)
284.00
284.50
292.00
284.00'
Surf.Area
(sq-ft)
10,443
12,601
24,121
143,469 cf
Device Routing Invert
Custom Stage Data (Prismatic)Listed below (Recalc)
Inc.Store
(cubic -feet)
0
5,761
137,708
Outlet Devices
Cum.Store
(cubic -feet)
0
5,761
143,469
#1 Primary 282.00'
#2 Device 1
#3 Device 1
284.00'
258.60'
24.0" Round Culvert
L= 50.0' RCP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 282.00' / 281.50' S= 0.0100 '/' Cc= 0.900
n= 0.013, Flow Area= 3.14 sf
2.0" Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads
6.0" W x 6.0" H Vert. Orifice/Grate C= 0.600
Limited to weir flow at low heads
Primary OutFlow Max=2.53 cfs @ 12.47 hrs HW=285.93' (Free Discharge)
4-1=Culvert (Passes 2.53 cfs of 25.89 cfs potential flow)
12=Orifice/Grate (Orifice Controls 0.14 cfs @ 6.54 fps)
3=Orifice/Grate (Orifice Controls 2.39 cfs @ 9.55 fps)

1886 SIA POST Type 11 24-hr 1-Year Rainfall=3.00"
Prepared by {enter your company name here} Printed 12/9/2021
HydroCAD® 10.10-6a s/n 03736 © 2020 HydroCAD Software Solutions LLC Page 18
Pond 8P: WDB#3
Hydrograph
32�
30�
28- �+
26- �+
24�
22
20 / r
• -
u • 18J
3 16��
0
a 141
10�
8J
61/
4� ,T
21
0
+ - - 4 - - +
▪ L L
I --+--+--+--I--+--+--+-------+--+--+
7 7 T
- - 4 - - 4
L L
7 7 T
4 - - 4 - - 4
7 7 T
4 - - 4 - - 4
7
T
7 7
7
+
I Li
I IL
t i-frow Area=9.-6'7 ao
T T
Peak EFevT28-5.p3'
Storage-25,-363 ec -
T
+
7 7 T
T
+
7 7 T
2.53 cfs
7 7 T
8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Time (hours)
• Inflow
• Primary

1886 SIA POST
Prepared by {enter your company name here}
HydroCAD® 10.10-6a s/n 03736 © 2020 HydroCAD Software Solutions LLC
Type 11 24-hr 1-Year Rainfall=3.00"
Printed 12/9/2021
Page 19
Inflow Area =
Inflow =
Outflow =
Primary =
Summary for Pond 9P: WDB#4
18.50 ac, 52.97% Impervious, Inflow Depth > 1.86" for 1-Year event
53.68 cfs @ 11.95 hrs, Volume= 2.862 af
0.76 cfs @ 18.29 hrs, Volume= 0.801 af, Atten= 99%, Lag= 380.3 min
0.76 cfs @ 18.29 hrs, Volume= 0.801 af
Routed to Link 4 : DP#4
Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs
Peak Elev= 305.11' @ 18.29 hrs Surf.Area= 33,795 sf Storage= 93,512 cf
Plug -Flow detention time= 456.5 min calculated for 0.799 af (28% of inflow)
Center -of -Mass det. time= 272.2 min (1,045.1 - 772.9 )
Volume Invert Avail.Storage Storage Description
#1
Elevation
(feet)
302.00
302.50
310.00
302.00'
Surf.Area
(sq-ft)
24,451
27,786
45,035
286,138 cf
Device Routing Invert
Custom Stage Data (Prismatic)Listed below (Recalc)
Inc.Store
(cubic -feet)
0
13,059
273,079
Outlet Devices
Cum.Store
(cubic -feet)
0
13,059
286,138
#1 Primary 296.00'
#2 Device 1
#3 Device 1
302.00'
303.60'
36.0" Round Culvert
L= 50.0' RCP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 296.00' / 295.50' S= 0.0100 '/' Cc= 0.900
n= 0.013, Flow Area= 7.07 sf
3.0" Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads
3.0" W x 3.0" H Vert. Orifice/Grate C= 0.600
Limited to weir flow at low heads
Primary OutFlow Max=0.76 cfs @ 18.29 hrs HW=305.11' (Free Discharge)
4-1=Culvert (Passes 0.76 cfs of 93.91 cfs potential flow)
12=Orifice/Grate (Orifice Controls 0.41 cfs @ 8.32 fps)
3=Orifice/Grate (Orifice Controls 0.35 cfs @ 5.67 fps)

1886 SIA POST Type 11 24-hr 1-Year Rainfall=3.00"
Prepared by {enter your company name here} Printed 12/9/2021
HydroCAD® 10.10-6a s/n 03736 © 2020 HydroCAD Software Solutions LLC Page 20
60�
55:- -
45� L
40�
N 35-
u =
3 30:�
0
25J
20� r
15� „1-
10--
0
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Time (hours)
A L L
7 7 r
▪ rt--r
▪ +--r
4
L
Pond 9P: WDB#4
Hydrograph
HI i i
hi H
1nfloaw;Area=1-$.60 ac -
POal PeV=1-05.14F
L L
Storage=93y512 cf
r
7 7 r
r r
✓ r
• r
• Inflow
• Primary

1886 SIA POST Type 11 24-hr 1-Year Rainfall=3.00"
Prepared by {enter your company name here} Printed 12/9/2021
HydroCAD® 10.10-6a s/n 03736 © 2020 HydroCAD Software Solutions LLC Page 21
Summary for Pond 10P: WDB#5
Inflow Area = 29.53 ac, 52.93% Impervious, Inflow Depth > 1.99" for 1-Year event
Inflow = 93.85 cfs @ 11.95 hrs, Volume= 4.893 af
Outflow = 2.19 cfs @ 15.13 hrs, Volume= 2.136 af, Atten= 98%, Lag= 190.5 min
Primary = 2.19 cfs @ 15.13 hrs, Volume= 2.136 af
Routed to Link 5 : DP#5
Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs
Peak Elev= 306.08' @ 15.13 hrs Surf.Area= 41,091 sf Storage= 146,657 cf
Plug -Flow detention time= 413.6 min calculated for 2.131 af (44% of inflow)
Center -of -Mass det. time= 277.4 min (1,053.1 - 775.7 )
Volume Invert Avail.Storage Storage Description
#1
Elevation
(feet)
302.00
302.50
310.00
302.00'
Surf.Area
(sq-ft)
28,583
32,278
50,725
326,477 cf
Device Routing Invert
Custom Stage Data (Prismatic)Listed below (Recalc)
Inc.Store
(cubic -feet)
0
15,215
311,261
Outlet Devices
Cum.Store
(cubic -feet)
0
15,215
326,477
#1 Primary 297.00'
#2 Device 1
#3 Device 1
302.00'
303.80'
36.0" Round Culvert
L= 50.0' RCP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 297.00' / 296.50' S= 0.0100 '/' Cc= 0.900
n= 0.013, Flow Area= 7.07 sf
3.0" Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads
6.0" W x 6.0" H Vert. Orifice/Grate C= 0.600
Limited to weir flow at low heads
Primary OutFlow Max=2.19 cfs @ 15.13 hrs HW=306.08' (Free Discharge)
4-1=Culvert (Passes 2.19 cfs of 93.72 cfs potential flow)
12=Orifice/Grate (Orifice Controls 0.47 cfs @ 9.58 fps)
3=Orifice/Grate (Orifice Controls 1.72 cfs @ 6.86 fps)

1886 SIA POST Type 11 24-hr 1-Year Rainfall=3.00"
Prepared by {enter your company name here} Printed 12/9/2021
HydroCAD® 10.10-6a s/n 03736 © 2020 HydroCAD Software Solutions LLC Page 22
0
105 _
1007:-�'
95
90
85
804-�
75
70 +
65
60� 1
557]-
Pond 10P: WDB#5
Hydrograph
i+ i 1
i
1 1- 4 1
93.85 cfs
4�
r
1 1 L I 1 L
i 1
1
1 L
1 L
+ 4- I 4 +
50
45�' I I I
4-
L
1
4-
Cn f o*-Areas=2 i53 ac
1300
1 1 1 1 1 LIL 1
■
Starage=1 4ekS5T cf - -
tri
L1 L i 1 1 L i 1 1
II II II II II II II
40_
3;0L
�
+ 1-+ + I +rr II
157:-/ + 1 + ▪ L
10
5�
5 6 7
i
1i 1it 1 ti
r I 4-
r
1 I +
L
2.19 cfs
Air
8 9 10 11 12 13 14 15 16 17
Time (hours)
18
19
20
21
22
23
24
• Inflow
• Primary

1886 SIA POST Type 11 24-hr 1-Year Rainfall=3.00"
Prepared by {enter your company name here} Printed 12/9/2021
HydroCAD® 10.10-6a s/n 03736 © 2020 HydroCAD Software Solutions LLC Page 23
Summary for Link 1: DP#1
Inflow Area = 19.43 ac, 51.88% Impervious, Inflow Depth > 1.27" for 1-Year event
Inflow = 2.82 cfs @ 13.11 hrs, Volume= 2.060 af
Primary = 2.82 cfs @ 13.11 hrs, Volume= 2.060 af, Atten= 0%, Lag= 0.0 min
Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs
0
L
Link 1: DP#1
Hydrograph
4
5
9 10 11 12 13 14
Time (hours)
15 16 17 18 19
20
21
22
23 24
❑ Inflow
❑ Primary

1886 SIA POST Type 11 24-hr 1-Year Rainfall=3.00"
Prepared by {enter your company name here} Printed 12/9/2021
HydroCAD® 10.10-6a s/n 03736 © 2020 HydroCAD Software Solutions LLC Page 24
Summary for Link 2: DP#2
Inflow Area = 26.48 ac, 45.01% Impervious, Inflow Depth > 0.59" for 1-Year event
Inflow = 4.06 cfs @ 12.02 hrs, Volume= 1.295 af
Primary = 4.06 cfs @ 12.02 hrs, Volume= 1.295 af, Atten= 0%, Lag= 0.0 min
Routed to nonexistent node 3A
Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs
Link 2: DP#2
Hydrograph
1
4-
nflow
3
4
dnArf
Area=26.4j.06 cfs
7
9 10 11 12 13 14 15
Time (hours)
16
17 18
19
20
21
22
23
24

1886 SIA POST Type 11 24-hr 1-Year Rainfall=3.00"
Prepared by {enter your company name here} Printed 12/9/2021
HydroCAD® 10.10-6a s/n 03736 © 2020 HydroCAD Software Solutions LLC Page 25
Summary for Link 3: DP#3
Inflow Area = 9.67 ac, 49.33% Impervious, Inflow Depth > 1.91" for 1-Year event
Inflow = 2.53 cfs @ 12.47 hrs, Volume= 1.535 af
Primary = 2.53 cfs @ 12.47 hrs, Volume= 1.535 af, Atten= 0%, Lag= 0.0 min
Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs
0
L
Link 3: DP#3
Hydrograph
Inflow Area=9.6
H
H
3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Time (hours)
❑ Inflow
❑ Primary

1886 SIA POST Type 11 24-hr 1-Year Rainfall=3.00"
Prepared by {enter your company name here} Printed 12/9/2021
HydroCAD® 10.10-6a s/n 03736 © 2020 HydroCAD Software Solutions LLC Page 26
Summary for Link 4: DP#4
Inflow Area = 22.54 ac, 43.48% Impervious, Inflow Depth > 0.48" for 1-Year event
Inflow = 1.53 cfs @ 12.07 hrs, Volume= 0.897 af
Primary = 1.53 cfs @ 12.07 hrs, Volume= 0.897 af, Atten= 0%, Lag= 0.0 min
Routed to nonexistent node 3B
Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs
0
T.
Link 4: DP#4
Hydrograph
1
nflow
1 rf
Area=22. 1.53 cfs
3 4 5 6 7 8 9 10 11 12 13 14 15
Time (hours)
16
17 18
19
20
21
22
23
24

1886 SIA POST Type 11 24-hr 1-Year Rainfall=3.00"
Prepared by {enter your company name here} Printed 12/9/2021
HydroCAD® 10.10-6a s/n 03736 © 2020 HydroCAD Software Solutions LLC Page 27
Summary for Link 5: DP#5
Inflow Area = 32.33 ac, 48.34% Impervious, Inflow Depth > 0.82" for 1-Year event
Inflow = 2.46 cfs @ 12.11 hrs, Volume= 2.204 af
Primary = 2.46 cfs @ 12.11 hrs, Volume= 2.204 af, Atten= 0%, Lag= 0.0 min
Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs
0
L
Link 5: DP#5
Hydrograph
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Time (hours)
❑ Inflow
❑ Primary

1886 SIA POST Type 11 24-hr 1-Year Rainfall=3.00"
Prepared by {enter your company name here} Printed 12/9/2021
HydroCAD® 10.10-6a s/n 03736 © 2020 HydroCAD Software Solutions LLC Page 27
Summary for Link 5: DP#5
Inflow Area = 32.33 ac, 48.34% Impervious, Inflow Depth > 0.82" for 1-Year event
Inflow = 2.46 cfs @ 12.11 hrs, Volume= 2.204 af
Primary = 2.46 cfs @ 12.11 hrs, Volume= 2.204 af, Atten= 0%, Lag= 0.0 min
Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs
0
L
Link 5: DP#5
Hydrograph
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Time (hours)
❑ Inflow
❑ Primary

Subcat
DP4
DP#1
Subcat DP#1
Reach
WDB#1
Q\
K\WDB#1
Subcat WDB #1
Routing Diagram for 1886 SIA POST
Prepared by {enter your company name here}, Printed 12/10/2021
HydroCAD® 10.10-6a s/n 03736 ©2020 HydroCAD Software Solutions LLC

1886 SIA POST
Prepared by {enter your company name here}
HydroCAD© 10.10-6a s/n 03736 © 2020 HydroCAD Software Solutions LLC
Printed 12/10/2021
Page 2
Rainfall Events Listing (selected events)
Event# Event Storm Type Curve Mode Duration B/B Depth AMC
Name (hours) (inches)
1 2-Year Type II 24-hr
2 10-Year Type II 24-hr
Default 24.00 1 3.57 2
Default 24.00 1 5.15 2

1886 SIA POST Type 11 24-hr 2-Year Rainfall=3.57"
Prepared by {enter your company name here} Printed 12/10/2021
HydroCAD® 10.10-6a s/n 03736 © 2020 HydroCAD Software Solutions LLC Page 3
Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points
Runoff by SCS TR-20 method, UH=SCS, Weighted-Q
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment DP#1: Subcat DP#1 Runoff Area=0.54 ac 0.00% Impervious Runoff Depth>0.66"
Tc=5.0 min CN=WQ Runoff=0.57 cfs 0.030 af
SubcatchmentWDB #1: Subcat WDB #1 Runoff Area=18.89 ac 53.36% Impervious Runoff Depth>2.57"
Tc=5.0 min CN=WQ Runoff=78.26 cfs 4.053 af
Pond 6P: WDB#1 Peak Elev=355.04' Storage=110,405 cf Inflow=78.26 cfs 4.053 af
Outflow=3.43 cfs 2.706 af
Link 1: DP#1 Inflow=3.48 cfs 2.736 af
Primary=3.48 cfs 2.736 af
Total Runoff Area = 19.43 ac Runoff Volume = 4.083 af Average Runoff Depth = 2.52"
48.12% Pervious = 9.35 ac 51.88% Impervious = 10.08 ac

1886 SIA POST Type 11 24-hr 2-Year Rainfall=3.57"
Prepared by {enter your company name here} Printed 12/10/2021
HydroCAD® 10.10-6a s/n 03736 © 2020 HydroCAD Software Solutions LLC Page 4
Summary for Subcatchment DP#1: Subcat DP#1
Runoff = 0.57 cfs @ 11.98 hrs, Volume=
Routed to Link 1 : DP#1
0.030 af, Depth> 0.66"
Runoff by SCS TR-20 method, UH=SCS, Weighted-Q, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs
Type II 24-hr 2-Year Rainfall=3.57"
Area (ac) CN Description
0.51 61 Open, good, HSG B
0.03 80 Open, good, HSG D
0.54 Weighted Average
0.54 62 100.00% Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
0.6-
0.55
0.5
0.45-
0.35�
`p 0.3� Lc5-.O- aJ to
tN =WQ- -
0.2
0.15�
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Time (hours)
Subcatchment DP#1: Subcat DP#1
Hydrograph
0.57 cfs
L
iypu11;24hr
2-Year Rainfa II 3.57"
Runoff Aroa=0L54 ac
Runoff 'VQlume='0.030 af
Runoff
Depth>0.66"
• Runoff

1886 SIA POST Type 11 24-hr 2-Year Rainfall=3.57"
Prepared by {enter your company name here} Printed 12/10/2021
HydroCAD® 10.10-6a s/n 03736 © 2020 HydroCAD Software Solutions LLC Page 5
Summary for Subcatchment WDB #1: Subcat WDB #1
Runoff = 78.26 cfs @ 11.95 hrs, Volume= 4.053 af, Depth> 2.57"
Routed to Pond 6P : WDB#1
Runoff by SCS TR-20 method, UH=SCS, Weighted-Q, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs
Type II 24-hr 2-Year Rainfall=3.57"
Area (ac) CN Description
0.03 61 Open, good, HSG B
8.78 80 Open, good, HSG D
0.08 98 Roadway, good, HSG B
2.95 98 Roadway, good, HSG D
2.69 98 Roof, good, HSG D
0.70 100 SCM, good, HSG D
0.03 98 Sidewalk, good, HSG B
3.63 98 Sidewalk, good, HSG D
18.89 Weighted Average
8.81 80 46.64% Pervious Area
10.08 98 53.36% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
0
5.0 Direct Entry,
85�
80
75
70
65�
60� z
55�
50
45�
40�
35�
30�
251
Subcatchment WDB #1: Subcat WDB #1
Hydrograph
t--t--r
1 1 L
78.26 cfs
- L
+
L
T
i
L
r
1-
L
o-
0 1
// /
2 3 4 5 6 7 8
L
PP
L L-
Type n 24-hr
--14--! 2 Yaar Rai f l 3.57�.. -
-- RwL L i L L np f-Arrea=t88SL ap--
L L
- - O n f-V-gI ie=4. `$- Of- -
T Runoff
rt
L L
4- 1- 4-
L 11-
L L
D pth Z 57�F
r
TcT5.40 min -
L
-1
L L
1 1 L H
L i r
.1. ... ... ... ... ... ... ... ... ... ... ... ... ... �,
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Time (hours)
• Runoff

1886 SIA POST
Prepared by {enter your company name here}
HydroCAD® 10.10-6a s/n 03736 © 2020 HydroCAD Software Solutions LLC
Type 11 24-hr 2-Year Rainfall=3.57"
Printed 12/10/2021
Page 6
Inflow Area =
Inflow =
Outflow =
Primary =
Summary for Pond 6P: WDB#1
18.89 ac, 53.36% Impervious, Inflow Depth > 2.57" for 2-Year event
78.26 cfs @ 11.95 hrs, Volume= 4.053 af
3.43 cfs @ 13.18 hrs, Volume= 2.706 af, Atten= 96%, Lag= 73.8 min
3.43 cfs @ 13.18 hrs, Volume= 2.706 af
Routed to Link 1 : DP#1
Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs
Peak Elev= 355.04' @ 13.18 hrs Surf.Area= 40,314 sf Storage= 110,405 cf
Plug -Flow detention time= 349.5 min calculated for 2.701 af (67% of inflow)
Center -of -Mass det. time= 244.8 min (1,017.8 - 772.9 )
Volume Invert Avail.Storage Storage Description
#1
Elevation
(feet)
352.00
352.50
362.00
352.00'
Surf.Area
(sq-ft)
30,383
34,023
57,578
451,206 cf
Device Routing Invert
Custom Stage Data (Prismatic)Listed below (Recalc)
I nc. Store
(cubic -feet)
0
16,102
435,105
Outlet Devices
Cum.Store
(cubic -feet)
0
16,102
451,206
#1 Primary 347.00'
#2 Device 1
#3 Device 1
352.00'
353.20'
36.0" Round Culvert
L= 50.0' CPP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 347.00' / 346.50' S= 0.0100 '/' Cc= 0.900
n= 0.013, Flow Area= 7.07 sf
3.0" Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads
12.0" W x 6.0" H Vert. Orifice/Grate C= 0.600
Limited to weir flow at low heads
Primary OutFlow Max=3.43 cfs @ 13.18 hrs HW=355.04' (Free Discharge)
4-1=Culvert (Passes 3.43 cfs of 87.02 cfs potential flow)
12=Orifice/Grate (Orifice Controls 0.40 cfs @ 8.22 fps)
3=Orifice/Grate (Orifice Controls 3.03 cfs @ 6.06 fps)

1886 SIA POST Type 11 24-hr 2-Year Rainfall=3.57"
Prepared by {enter your company name here} Printed 12/10/2021
HydroCAD® 10.10-6a s/n 03736 © 2020 HydroCAD Software Solutions LLC Page 7
85�
80
75
70
65�
607-:
55�
• 50
• 45-
3
0 40:,
35�
30�
25�
0
Pond 6P: WDB#1
Hydrograph
▪ r--r
-I 4 r
4 4 r
▪ 11
r
78.26 cfs
7 7 7
r--r
-I 4 r
4 4 r
▪ 1 L
7 r
r
biflowiArea=* 89 Lac
P lei=1`5504'
7
✓
✓
1
Stor'rge=410 405-Ef -
▪ T r
r
4 4 r
1 1 1
3
43 cfs
✓ r
Y r
9
10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Time (hours)
• Inflow
• Primary

1886 SIA POST Type 11 24-hr 2-Year Rainfall=3.57"
Prepared by {enter your company name here} Printed 12/10/2021
HydroCAD® 10.10-6a s/n 03736 © 2020 HydroCAD Software Solutions LLC Page 8
Summary for Link 1: DP#1
Inflow Area = 19.43 ac, 51.88% Impervious, Inflow Depth > 1.69" for 2-Year event
Inflow = 3.48 cfs @ 13.02 hrs, Volume= 2.736 af
Primary = 3.48 cfs @ 13.02 hrs, Volume= 2.736 af, Atten= 0%, Lag= 0.0 min
Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs
0
L
Link 1: DP#1
Hydrograph
4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Time (hours)
❑ Inflow
❑ Primary

1886 SIA POST Type 11 24-hr 10-Year Rainfall=5.15"
Prepared by {enter your company name here} Printed 12/10/2021
HydroCAD® 10.10-6a s/n 03736 © 2020 HydroCAD Software Solutions LLC Page 9
Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points
Runoff by SCS TR-20 method, UH=SCS, Weighted-Q
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment DP#1: Subcat DP#1 Runoff Area=0.54 ac 0.00% Impervious Runoff Depth>1.55"
Tc=5.0 min CN=WQ Runoff=1.46 cfs 0.070 af
SubcatchmentWDB #1: Subcat WDB #1 Runoff Area=18.89 ac 53.36% Impervious Runoff Depth>4.04"
Tc=5.0 min CN=WQ Runoff=121.93 cfs 6.353 af
Pond 6P: WDB#1 Peak Elev=356.61' Storage=176,862 cf Inflow=121.93 cfs 6.353 af
Outflow=4.78 cfs 4.220 af
Link 1: DP#1 Inflow=5.41 cfs 4.290 af
Primary=5.41 cfs 4.290 af
Total Runoff Area = 19.43 ac Runoff Volume = 6.422 af Average Runoff Depth = 3.97"
48.12% Pervious = 9.35 ac 51.88% Impervious = 10.08 ac

1886 SIA POST Type 11 24-hr 10-Year Rainfall=5.15"
Prepared by {enter your company name here} Printed 12/10/2021
HydroCAD® 10.10-6a s/n 03736 © 2020 HydroCAD Software Solutions LLC Page 10
Summary for Subcatchment DP#1: Subcat DP#1
Runoff = 1.46 cfs @ 11.97 hrs, Volume=
Routed to Link 1 : DP#1
0.070 af, Depth> 1.55"
Runoff by SCS TR-20 method, UH=SCS, Weighted-Q, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs
Type II 24-hr 10-Year Rainfall=5.15"
Area (ac) CN Description
0.51 61 Open, good, HSG B
0.03 80 Open, good, HSG D
0.54 Weighted Average
0.54 62 100.00% Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
Subcatchment DP#1: Subcat DP#1
Hydrograph
1.46 cfs
o
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Time (hours)
dr
Type II 24-hr
10-Year RainfallT5.15"
Runoff Area=0.54 ac
Runoff VQlume=r0.O7O of
Runoff Depth>1.55"
TcT5.0 miff
CN=WQ
❑ Runoff

1886 SIA POST Type 11 24-hr 10-Year Rainfall=5.15"
Prepared by {enter your company name here} Printed 12/10/2021
HydroCAD® 10.10-6a s/n 03736 © 2020 HydroCAD Software Solutions LLC Page 11
Summary for Subcatchment WDB #1: Subcat WDB #1
Runoff = 121.93 cfs @ 11.95 hrs, Volume= 6.353 af, Depth> 4.04"
Routed to Pond 6P : WDB#1
Runoff by SCS TR-20 method, UH=SCS, Weighted-Q, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs
Type II 24-hr 10-Year Rainfall=5.15"
Area (ac) CN Description
0.03 61 Open, good, HSG B
8.78 80 Open, good, HSG D
0.08 98 Roadway, good, HSG B
2.95 98 Roadway, good, HSG D
2.69 98 Roof, good, HSG D
0.70 100 SCM, good, HSG D
0.03 98 Sidewalk, good, HSG B
3.63 98 Sidewalk, good, HSG D
18.89 Weighted Average
8.81 80 46.64% Pervious Area
10.08 98 53.36% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
130-
120--
do-/
100—
90—
r
- 80
70--
3
50-
40—
30_
T
Subcatchment WDB #1: Subcat WDB #1
Hydrograph
+ L L L L
4 4 4 4
- r 7 -T
- 7 Ti T P 7
L
L
20—
10—
0
1 2 3 4 5 6 7
4-
✓
4 4
H -+
H 7
L
Type II 24-hir
10-Year RainfaI I5 i15" -
RtnbfAiea=1-8-a9-at -
�4 VOme_6--45$ Runoff Depth >4.O4 F -
L + L
L
TcT5.0 Min
CN=WQ
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Time (hours)

1886 SIA POST
Prepared by {enter your company name here}
HydroCAD® 10.10-6a s/n 03736 © 2020 HydroCAD Software Solutions LLC
Type 11 24-hr 10-Year Rainfall=5.15"
Printed 12/10/2021
Page 12
Summary for Pond 6P: WDB#1
Inflow Area = 18.89 ac, 53.36% Impervious, Inflow Depth > 4.04" for 10-Year event
Inflow = 121.93 cfs @ 11.95 hrs, Volume= 6.353 af
Outflow = 4.78 cfs @ 13.36 hrs, Volume= 4.220 af, Atten= 96%, Lag= 84.6 min
Primary = 4.78 cfs @ 13.36 hrs, Volume= 4.220 af
Routed to Link 1 : DP#1
Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs
Peak Elev= 356.61' @ 13.36 hrs Surf.Area= 44,213 sf Storage= 176,862 cf
Plug -Flow detention time= 371.4 min calculated for 4.211 af (66% of inflow)
Center -of -Mass det. time= 267.6 min (1,034.4 - 766.8 )
Volume Invert Avail.Storage Storage Description
#1
Elevation
(feet)
352.00
352.50
362.00
352.00'
Surf.Area
(sq-ft)
30,383
34,023
57,578
451,206 cf
Device Routing Invert
Custom Stage Data (Prismatic)Listed below (Recalc)
Inc.Store
(cubic -feet)
0
16,102
435,105
Outlet Devices
Cum.Store
(cubic -feet)
0
16,102
451,206
#1 Primary 347.00'
#2 Device 1
#3 Device 1
352.00'
353.20'
36.0" Round Culvert
L= 50.0' CPP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 347.00' / 346.50' S= 0.0100 '/' Cc= 0.900
n= 0.013, Flow Area= 7.07 sf
3.0" Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads
12.0" W x 6.0" H Vert. Orifice/Grate C= 0.600
Limited to weir flow at low heads
Primary OutFlow Max=4.78 cfs @ 13.36 hrs HW=356.61' (Free Discharge)
4-1=Culvert (Passes 4.78 cfs of 96.92 cfs potential flow)
12=Orifice/Grate (Orifice Controls 0.50 cfs @ 10.20 fps)
3=Orifice/Grate (Orifice Controls 4.28 cfs @ 8.56 fps)

1886 SIA POST Type 11 24-hr 10-Year Rainfall=5.15"
Prepared by {enter your company name here} Printed 12/10/2021
HydroCAD® 10.10-6a s/n 03736 © 2020 HydroCAD Software Solutions LLC Page 13
Pond 6P: WDB#1
Hydrograph
130�
120''
1101▪ "�
100:"
90�
80� ,,h
▪ 701"
i° 60�
50��
401▪ "
30:-
20�
101"
0
121.93 cfs
7
y
4
Inflow Area=18.89 ac
y
-talc giOV=456;61''
p_torage=11768p cf
4
4.78 cfs
/7
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Time (hours)
• Inflow
• Primary

1886 SIA POST Type 11 24-hr 10-Year Rainfall=5.15"
Prepared by {enter your company name here} Printed 12/10/2021
HydroCAD® 10.10-6a s/n 03736 © 2020 HydroCAD Software Solutions LLC Page 14
Summary for Link 1: DP#1
Inflow Area = 19.43 ac, 51.88% Impervious, Inflow Depth > 2.65" for 10-Year event
Inflow = 5.41 cfs @ 12.00 hrs, Volume= 4.290 af
Primary = 5.41 cfs @ 12.00 hrs, Volume= 4.290 af, Atten= 0%, Lag= 0.0 min
Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs
� 5
4—,
u -
3 3—
o -
2-
Link 1: DP#1
Hydrograph
L
4-
L
7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Time (hours)
❑ Inflow
❑ Primary

Site -to -Drainage Area Analysis

1886 - 1101 Olive Branch Road
Site to Drainage Area Analysis
.,
L-f Cr
1#k3
illAvNvok
,4,1ril_f, ci
50& vcrizr- _ Z_ZW 14( f
TOTAL DRAINAGE TO
DP#3 =1,594 ACRES
d4. _ 4°6'411
4.1? TNI ��
1
rAik
U� J
/7 ko 1�
- 2
/\ . /ill 'P ) n 1 1 \�
SITE AREA (SA) = 162 ACRES
DRAINAGE AREA (DA) = 1,594 ACRES 1
(SA/DA = 1,594/162 = 10.2%
4'S0•-•

Required Maps and Information

1886 - OLIVE BRANCH RD
USGS MAP
DURHAM SOUTH EAST QUADRANGLE
SCALE 1:24,000 N

SEERS REPORT FOR 20NE DESCRIPTIONS AND INDEX MAP
THE INFORMATION DEPICTED ON THIS MAP AND SUPP0R1ING
DOCUMENTATION ARE ALSO AVAILABLE IN DIGITAL FORMATAT
HTTP://FRIS.NC.GOV/FRIS
WRhauttlasol ood Elevation WBFE)
With 6FE or Depth zone AE. ID. AH. IE, AR
MERegulatory Floodway
0.2%Annual Chance Flood Hazard, Areas
of 1% Annual Chance Flood with Average
Depth Less Than One Foot Or With Drainage
Areas of Less Than One Square Mile Tone x
— Future Conditions 1%Annual
Chance Flood Hazard Zo:e x
OTHER AREAS OF — Area with Reduced Flood Risk due to Levee
FLOOD HAZARD See Notes zone
OTHER — aaetemlbsidethe
AREAS 0.2%AAreDnnual Chinedtoance Fl0odplaineoutzonex
- Channel, Culvert, or Storm Sewer
» Accredited or Provisionally Accredited
Levee, Dike, or Floodwall
I„ii1,ii1i Non -accredited levee, Dike, or Flaodwall
51Ox North Carolina Geodetic Survey bench mark
sIO® National Geodetic Survey bench mark
S%D® Contractor Est NCFMP Survey bench mark
0-yes— Cross Sections with l%Annual Chance
Water Surface Elevation (BFE)
Coastal Transept
- ------ Coastal Transect Baseline
Profile Baseline
Hydrographie Feature
OTHER limit of Study
FEATURES - Jurisdiction Boundary
FLOOD HAZARD INFORMATION
SPECML FLOOD
HAZARD AREAS
GENERAL
STRUCIURES
NOTES TO USERS
Nap se
limit of Moderate Wave Action (LiMWA)
COASTAL BARRIER RESOURCES SYSTEM ICBRSI NOTE
CBRS Area
SCALE
e
lmi.: eN12mettWl Iwledim f
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O 75 150 300
PANEL LOCATOR
i
08/1
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0636
00.12
es
PAO
4
NORTH CAROUNA FLOODPIAIN MAPPING PROGRAM
NATIONAL FLOOD INSURANCE PROGRAM
co FLOOD INSURANCE RATE MAP
o NORTH CAROLINA
a —ono
ci
CT
Panel Contains:
COMMUNIIy
oaf
0260
0178
FEMI
CID PANEL SUM/
VERSION NUMBER
2.3.3.2
3720086000N
MAP REVISED
October 2018

20700D0 FEET
010000 FEET
800000 FEET
78,15.30,1
70,1610,111
SITE
Continues to the West
X18011[11, FEET
FLOOD HAZARD INFORMATION
NOTES TO USERS
SCALE
SEERS REPORT FOR 20NE DESCRIPTIONS AND INDEX MAP
THE INFORMATION DEPICTED ON THIS MAP AND SUPORCING
DOCUMENTATION ARE ALSO AVAILABLE IN DIGITAL FORMATAT
HTTP://FRIS.NC.GOV/FRIS
WRRsol ood Elevation(BFE) wdnautt Oa0FEor Depth zone AE, Ao, AH. PE AR
SPECML FLOOD Regulatory Fl00dway
HAZARD AREAS I�
0.2%Annual Chance Flood Hazard, Areas
of 1% Annual Chance Flood with Average
Depth Less Than One Foot or With Drainage
Areas of Less Than One Square Mile nine x
- Future Conditions 1%Annual
Chance Flood Hazard x
OTHER AREAS OF — Area with Reduced Flood Risk due to Levee
FLOOD HAZARD See Notes zone
OTHER — asetemldbe0usidethe
AREAS 0.2Are%ADnnual ChineancetoFl0odplaietzonex
- Channel, Culvert, or Storm Sewer
»»»»»m Accredited or Provisionally Accredited
GENERAL Levee, Dike, or Floodwall
STRUMMER 1.111141001 Non -accredited levee, Dike, or Floodwall
x North Carolina Geodetic Survey bench mark
sIO® National Geodetic Survey bench mark
510. Contractor Est NCFMP Survey bench mark
0-yes— Cross Sections with l%Annual Chance
Water Surface Elevation (BEE)
Coastal Transect
- ------ Coastal Transect Baseline
Profile Baseline
Hydrographin Feature
OTHER limit of Study
FEATURES - Jurisdiction Boundary
1.180 Se
limit of Moderate Wave Action (LiMWA)
COASTAL BARRIER RESOURCES SYSTEM (CBR.) NOTE
CBRS Area
e
lmi.: eetlZ e33Wl Iwledim f
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O 250 500 1.000eet
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PANEL LOCATOR
i
0-0
0721
0532
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08.2
0610
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0.53
0805
0850
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NORTH CAROUNA FL00DPLAIN MAPPING PROGRAM
NATIONAL FLOOD INSURANCE PROGRAM
co FLOOD INSURANCE RATE MAP
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VERSION NUMBER
2.3.3.2
KW AMMER
3720087000N
MAP REVISED
October 2018

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Soil Rating Points
« 2 = 2
■ ■ ■ ■
Natural Resources
Conservation Service

Hydrologic Soil Group —Durham County, North Carolina
Web Soil Survey
Hydrologic Soil Group
Map unit symbol
Map unit name
Rating
Acres in AOI
Percent of AOI
Ch
Chewacla and
Wehadkee soils, 0 to
2 percent slopes,
frequently flooded
B/D
51.9
8.8%
Gu
Gullied land, clayey
materials
9.6
1.6%
MfE
Mayodan sandy loam,
15 to 25 percent
slopes
B
1.7
0.3%
PfE
Pinkston fine sandy
loam, 10 to 25 percent
slopes
B
82.0
14.0%
Ur
Urban land
0.9
0.1 %
WsB
White Store sandy loam,
2 to 6 percent slopes
D
80.6
13.7%
WsC
White Store sandy loam,
6 to 10 percent slopes
D
98.0
16.7%
WsE
White Store sandy loam,
10 to 25 percent
slopes
D
238.2
40.5%
WvC2
White Store clay loam, 2
to 10 percent slopes,
moderately eroded
D
18.7
3.2%
WvE2
White Store clay loam,
10 to 25 percent
slopes, moderately
eroded
D
6.2
1.1 %
Totals for Area of Interest
587.8
100.0%
USDA Natural Resources Web Soil Survey
Conservation Service National Cooperative Soil Survey
3/15/2021
Page 3 of 4

Hydrologic Soil Group —Durham County, North Carolina Web Soil Survey
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
USDA Natural Resources Web Soil Survey
Conservation Service National Cooperative Soil Survey
3/15/2021
Page 4 of 4

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