20200572 Ver 1_Grove SW Report_2020-01-30_20200428

STORMWATER
MANAGEMENT REPORT

FOR

GROVE AVENUE SUBDIVISION
738 GROVE AVE
RALEIGH, NC

January 30, 2020

PREPARED BY:
FLM Engineering, Inc.
PO Box 91727
Raleigh, NC 27675
919.423.8975
NC License No. C-4222

© 2020 FLM Engineering, Inc. Page 2 of 5 January 30, 2020

Table of Contents

1.0 Introduction ........................................................................................................................ 3
2.0 Site Description .................................................................................................................. 3
3.0 Proposed Development ...................................................................................................... 3
4.0 Stormwater Analysis .......................................................................................................... 3
4.1 Flood Study .................................................................................................................... 3
4.2 Stormwater Impact Analysis ........................................................................................... 4
4.3 Stormwater Management ............................................................................................... 4
4.4 Nutrient Calculations ...................................................................................................... 5
4.5 Operations and Maintenance ......................................................................................... 5
5.0 Limitations .......................................................................................................................... 5

Tables

Table 4-1 Stormwater Management Summary
Table 4-2 Nutrient Load Summary

Appendices

Appendix A Flood Study Watershed Map
Appendix B Flood Study
Appendix C NRCS Soils Report
Appendix D Stormwater Impact Analysis Watershed Map
Appendix E Pre- and Post-Development Watershed Maps
Appendix F Pre-Development Hydrologic Model
Appendix G Post-Development Hydrologic Model
Appendix H Nutrient Calculations
Appendix I HGL Calculations
Appendix J Operations and Maintenance Manual

© 2020 FLM Engineering, Inc. Page 3 of 5 January 30, 2020

1.0 Introduction

A Squared, LLC is proposed a 15-lot single family subdivision in Raleigh, North Carolina on Wake
County PIN # 0783-38-79115. This report details the stormwater management design for the
project.

2.0 Site Description

The existing 8.43-acre project area is wooded and contains a buffered stream and wetlands that
bisect the site. The site is bordered by Grove Avenue to the east and single family residences on
the north, south and west parcel boundaries. Based on the Wake County iMaps soil maps, flood
hazard soils are present on site. A flood study was performed and is presented here in section
4.1. Based on our sketch plan review (trans. # 556648), there is a documented case of
downstream structural flooding. The stormwater impact analysis is presented here in section 4.2.

3.0 Proposed Development

Onsite built-upon area coverage was broken down as follows:
 Roadways: 0.50 ac
 Lots (4,000 sf/lot): 1.38 ac
 Sidewalk: 0.13 ac

Total: 2.01 ac (23.8% built upon area)

4.0 Stormwater Analysis

4.1 Flood Study

Due to the presence of existing flood hazard soils, a flood study was performed to determine the
approximate elevation of the 100-year storm. The watershed was modeled using HEC-RAS
software and it was determined that the 100-year flood elevation was mostly within the existing
stream buffer. The flood boundary is shown on the preliminary subdivision plans. The proposed
© 2020 FLM Engineering, Inc. Page 4 of 5 January 30, 2020

grading limits do not encroach the flood boundary. The flood study watershed map is included in
appendix A. The flood study and NRCS soils reports are included as appendices B and C,
respectively.

4.2 Stormwater Impact Analysis

Due to a documented case of downstream structural flooding, a stormwater impact analysis was
performed in accordance with City of Raleigh Unified Development Ordinance (UDO) section
9.2.2.E.3.a. The watershed map is included in Appendix D. The subject property is less than 5%
of the drainage area, measured to the location of the documented structural flooding, and is
exempt from additional runoff controls per UDO section 9.2.2.E.3.d

4.3 Stormwater Management

The east side of the parcel was analyzed for the 2- and 10-year, 24-hour storm events. Areas of
the parcel west of the stream are to remain vacant (open space and tree conservation areas) and
were not included in the analysis. The area east of the site drains through the site and is routed
through the proposed stormwater control measure (SCM). Areas north of the site that drain
through the parcel are designed to be bypassed and were not included in the analysis. A dry
detention pond is proposed to treat the majority of impervious runoff from the site. Watershed
maps for pre- and post-development conditions are included as appendix E. Pre- and post-
development hydrologic results are included as appendices F and G, respectively.

Table 4-1
Pre-development Hydrologic Model Results
Storm Event
(24-hour)
Pre-development
(cfs)
Post-development
(cfs)
2-year 6.07 4.65
10-year 18.24 11.69

The hydraulic grade line calculations for the proposed storm system are included in Appendix H.

© 2020 FLM Engineering, Inc. Page 5 of 5 January 30, 2020

4.4 Nutrient Calculations

The nutrient calculations are shown on the plans and in Appendix I. The nutrient loading
requirements are anticipated to be met via buydown methods. The existing right-of-way along
Grove Avenue does not require any additional improvements that would increase the existing
impervious area within the Grove Avenue right-of-way. Proposed tree conservation areas were
credited as “permanently preserved undisturbed open space”.

Table 4-2
Nutrient Load Summary
Nutrient Pre-development Post-development
Total Nitrogen
Loading (lb/ac/yr) 0.60 5.91

4.5 Operations and Maintenance
An operations and maintenance manual for the proposed dry detention pond is included in
Appendix J.

5.0 Limitations

This work was performed in a manner consistent with the level of care and skill ordinarily
exercised by other members of FLM Engineering’s (FLM) profession practicing in the same
locality, and under similar conditions, as of the date any services were provided. FLM’s opinions
and recommendations were necessarily based on a limited number of data and observations. It
is possible that actual conditions could vary beyond the data evaluated. Therefore, FLM makes
no guarantee or warranty, express or implied, regarding any services, communications, reports,
opinions, or instruments of service provided.

APPENDIX A
FLOOD STUDY WATERSHED MAP

FLOOD STUDYWATERSHED MAPAPPX. A10250250125SCALE: 1 INCH = 250 FEETNGROVE AVENUE WESTERN BOULEVARDFLOOD STUDYWATERSHED225 ACRESSITEJONES FRANKLIN ROAD CHAPEL HILL ROAD

APPENDIX B
FLOOD STUDY

Flood Study
500
400
300
200
100
0 St
r
eam Alignment

HEC-RAS Plan: Plan 01 River: Stream Alignment Reach: Flood Study Profile: PF 1
Reach River Sta Profile Q Total Min Ch El W.S. Elev Crit W.S. E.G. Elev E.G. Slope Vel Chnl Flow Area Top Width Froude # Chl
(cfs) (ft) (ft) (ft) (ft) (ft/ft) (ft/s) (sq ft) (ft)
Flood Study 500 PF 1 1085.73 412.00 418.63 417.56 419.72 0.013690 8.37 129.72 68.07 1.07
Flood Study 400 PF 1 1085.73 411.99 417.92 418.55 0.008016 6.35 170.98 95.79 0.84
Flood Study 300 PF 1 1085.73 410.98 416.78 416.70 417.59 0.011087 7.23 150.09 86.01 0.97
Flood Study 200 PF 1 1085.73 410.00 416.03 416.59 0.007825 6.00 180.84 109.92 0.82
Flood Study 100 PF 1 1085.73 409.13 414.89 414.89 415.58 0.013267 6.67 162.80 125.18 1.03
Flood Study 0 PF 1 1085.73 408.00 413.30 413.30 414.03 0.012489 6.83 158.91 112.22 1.01

0 20 40 60 80 100 120 140 160
412
414
416
418
420
422
Grove Ave Flood Study Plan: Plan 01 2/26/2019

Station (ft)Elevation (ft)Legend
EG PF 1
WS PF 1
Crit PF 1
Ground
Bank Sta
.03

0 20 40 60 80 100 120 140
411
412
413
414
415
416
417
418
419
Grove Ave Flood Study Plan: Plan 01 2/26/2019

Station (ft)Elevation (ft)Legend
EG PF 1
WS PF 1
Ground
Bank Sta
.03

0 50 100 150 200
410
412
414
416
418
420
Grove Ave Flood Study Plan: Plan 01 2/26/2019

Station (ft)Elevation (ft)Legend
EG PF 1
WS PF 1
Crit PF 1
Ground
Bank Sta
.03

0 50 100 150 200 250
410
412
414
416
418
420
Grove Ave Flood Study Plan: Plan 01 2/26/2019

Station (ft)Elevation (ft)Legend
EG PF 1
WS PF 1
Ground
Bank Sta
.03

0 50 100 150 200
408
410
412
414
416
418
420
Grove Ave Flood Study Plan: Plan 01 2/26/2019

Station (ft)Elevation (ft)Legend
EG PF 1
WS PF 1
Crit PF 1
Ground
Bank Sta
.03

0 50 100 150 200
408
410
412
414
416
418
Grove Ave Flood Study Plan: Plan 01 2/26/2019

Station (ft)Elevation (ft)Legend
EG PF 1
WS PF 1
Crit PF 1
Ground
Bank Sta
.03
1S
Grove Ave Flood
Watershed
Drainage Diagram for Flood Study
Prepared by FLM Engineering, Printed 3/7/2019
HydroCAD® 8.50 s/n 002245 © 2007 HydroCAD Software Solutions LLC
Subcat Reach Pond Link
Flood Study
Printed 3/7/2019Prepared by FLM Engineering
Page 2HydroCAD® 8.50 s/n 002245 © 2007 HydroCAD Software Solutions LLC
Area Listing (selected nodes)
Area
(acres)
CN Description
(subcatchment-numbers)
51.960 51 1 acre lots, 20% imp, HSG A (1S)
31.340 68 1 acre lots, 20% imp, HSG B (1S)
3.870 77 1/8 acre lots, 65% imp, HSG A (1S)
17.980 84 1 acre lots, 20% imp, HSG D (1S)
1.470 85 1/8 acre lots, 65% imp, HSG B (1S)
14.160 89 Urban commercial, 85% imp, HSG A (1S)
12.910 92 1/8 acre lots, 65% imp, HSG D (1S)
0.240 92 Urban commercial, 85% imp, HSG B (1S)
91.470 95 Urban commercial, 85% imp, HSG D (1S)
225.400 TOTAL AREA
Flood Study
Printed 3/7/2019Prepared by FLM Engineering
Page 3HydroCAD® 8.50 s/n 002245 © 2007 HydroCAD Software Solutions LLC
Soil Listing (selected nodes)
Area
(acres)
Soil
Goup
Subcatchment
Numbers
69.990 HSG A 1S
33.050 HSG B 1S
0.000 HSG C
122.360 HSG D 1S
0.000 Other
225.400 TOTAL AREA
Type II 24-hr 100-Year Rainfall=7.51"Flood Study
Printed 3/7/2019Prepared by FLM Engineering
Page 4HydroCAD® 8.50 s/n 002245 © 2007 HydroCAD Software Solutions LLC
Summary for Subcatchment 1S: Grove Ave Flood Watershed
Runoff = 1,085.73 cfs @ 12.19 hrs, Volume= 88.035 af, Depth> 4.69"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24-hr 100-Year Rainfall=7.51"
Area (ac) CN Description
91.470 95 Urban commercial, 85% imp, HSG D
0.240 92 Urban commercial, 85% imp, HSG B
14.160 89 Urban commercial, 85% imp, HSG A
17.980 84 1 acre lots, 20% imp, HSG D
31.340 68 1 acre lots, 20% imp, HSG B
51.960 51 1 acre lots, 20% imp, HSG A
12.910 92 1/8 acre lots, 65% imp, HSG D
1.470 85 1/8 acre lots, 65% imp, HSG B
3.870 77 1/8 acre lots, 65% imp, HSG A
225.400 79 Weighted Average
103.292 Pervious Area
122.108 Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
1.2 100 0.0200 1.43 Sheet Flow, Sheet Flow
Smooth surfaces n= 0.011 P2= 3.47"
15.7 1,729 0.0150 1.84 Shallow Concentrated Flow, Shallow Concentrated
Grassed Waterway Kv= 15.0 fps
8.6 4,334 0.0128 8.38 2,631.86 Channel Flow, Channel Flow
Area= 314.0 sf Perim= 111.5' r= 2.82'
n= 0.040 Winding stream, pools & shoals
25.5 6,163 Total
Type II 24-hr 100-Year Rainfall=7.51"Flood Study
Printed 3/7/2019Prepared by FLM Engineering
Page 5HydroCAD® 8.50 s/n 002245 © 2007 HydroCAD Software Solutions LLC
Subcatchment 1S: Grove Ave Flood Watershed
Runoff
Hydrograph
Time (hours)
201918171615141312111098765Flow (cfs)1,200
1,150
1,100
1,050
1,000
950
900
850
800
750
700
650
600
550
500
450
400
350
300
250
200
150
100
50
0
Type II 24-hr 100-Year
Rainfall=7.51"
Runoff Area=225.400 ac
Runoff Volume=88.035 af
Runoff Depth>4.69"
Flow Length=6,163'
Tc=25.5 min
CN=79
1,085.73 cfs

APPENDIX C
NRCS SOILS REPORT

United States
Department of
Agriculture
A product of the National
Cooperative Soil Survey,
a joint effort of the United
States Department of
Agriculture and other
Federal agencies, State
agencies including the
Agricultural Experiment
Stations, and local
participants
Custom Soil Resource
Report for
Wake County,
North Carolina
Grove Flood Study Boundary
Natural
Resources
Conservation
Service
February 26, 2019
Preface
Soil surveys contain information that affects land use planning in survey areas.
They highlight soil limitations that affect various land uses and provide information
about the properties of the soils in the survey areas. Soil surveys are designed for
many different users, including farmers, ranchers, foresters, agronomists, urban
planners, community officials, engineers, developers, builders, and home buyers.
Also, conservationists, teachers, students, and specialists in recreation, waste
disposal, and pollution control can use the surveys to help them understand,
protect, or enhance the environment.
Various land use regulations of Federal, State, and local governments may impose
special restrictions on land use or land treatment. Soil surveys identify soil
properties that are used in making various land use or land treatment decisions.
The information is intended to help the land users identify and reduce the effects of
soil limitations on various land uses. The landowner or user is responsible for
identifying and complying with existing laws and regulations.
Although soil survey information can be used for general farm, local, and wider area
planning, onsite investigation is needed to supplement this information in some
cases. Examples include soil quality assessments (http://www.nrcs.usda.gov/wps/
portal/nrcs/main/soils/health/) and certain conservation and engineering
applications. For more detailed information, contact your local USDA Service Center
(https://offices.sc.egov.usda.gov/locator/app?agency=nrcs) or your NRCS State Soil
Scientist (http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/contactus/?
cid=nrcs142p2_053951).
Great differences in soil properties can occur within short distances. Some soils are
seasonally wet or subject to flooding. Some are too unstable to be used as a
foundation for buildings or roads. Clayey or wet soils are poorly suited to use as
septic tank absorption fields. A high water table makes a soil poorly suited to
basements or underground installations.
The National Cooperative Soil Survey is a joint effort of the United States
Department of Agriculture and other Federal agencies, State agencies including the
Agricultural Experiment Stations, and local agencies. The Natural Resources
Conservation Service (NRCS) has leadership for the Federal part of the National
Cooperative Soil Survey.
Information about soils is updated periodically. Updated information is available
through the NRCS Web Soil Survey, the site for official soil survey information.
The U.S. Department of Agriculture (USDA) prohibits discrimination in all its
programs and activities on the basis of race, color, national origin, age, disability,
and where applicable, sex, marital status, familial status, parental status, religion,
sexual orientation, genetic information, political beliefs, reprisal, or because all or a
part of an individual's income is derived from any public assistance program. (Not
all prohibited bases apply to all programs.) Persons with disabilities who require
2
alternative means for communication of program information (Braille, large print,
audiotape, etc.) should contact USDA's TARGET Center at [phone] (voice
and TDD). To file a complaint of discrimination, write to USDA, Director, Office of
Civil Rights, 1400 Independence Avenue, S.W., Washington, D.C. 20250-9410 or
call [phone] (voice) or [phone] (TDD). USDA is an equal opportunity
provider and employer.
3
Contents
Preface....................................................................................................................2
How Soil Surveys Are Made..................................................................................5
Soil Map..................................................................................................................8
Soil Map................................................................................................................9
Legend................................................................................................................10
Map Unit Legend................................................................................................11
Map Unit Descriptions.........................................................................................11
Wake County, North Carolina..........................................................................13
CfC—Cecil-Urban land complex, 2 to 10 percent slopes............................13
ChA—Chewacla and Wehadkee soils, 0 to 2 percent slopes,
frequently flooded.................................................................................14
PbD—Pacolet-Urban land complex, 10 to 15 percent slopes.....................16
Ur—Urban land...........................................................................................17
Soil Information for All Uses...............................................................................19
Soil Properties and Qualities..............................................................................19
Soil Qualities and Features.............................................................................19
Hydrologic Soil Group.................................................................................19
References............................................................................................................24
4
How Soil Surveys Are Made
Soil surveys are made to provide information about the soils and miscellaneous
areas in a specific area. They include a description of the soils and miscellaneous
areas and their location on the landscape and tables that show soil properties and
limitations affecting various uses. Soil scientists observed the steepness, length,
and shape of the slopes; the general pattern of drainage; the kinds of crops and
native plants; and the kinds of bedrock. They observed and described many soil
profiles. A soil profile is the sequence of natural layers, or horizons, in a soil. The
profile extends from the surface down into the unconsolidated material in which the
soil formed or from the surface down to bedrock. The unconsolidated material is
devoid of roots and other living organisms and has not been changed by other
biological activity.
Currently, soils are mapped according to the boundaries of major land resource
areas (MLRAs). MLRAs are geographically associated land resource units that
share common characteristics related to physiography, geology, climate, water
resources, soils, biological resources, and land uses (USDA, 2006). Soil survey
areas typically consist of parts of one or more MLRA.
The soils and miscellaneous areas in a survey area occur in an orderly pattern that
is related to the geology, landforms, relief, climate, and natural vegetation of the
area. Each kind of soil and miscellaneous area is associated with a particular kind
of landform or with a segment of the landform. By observing the soils and
miscellaneous areas in the survey area and relating their position to specific
segments of the landform, a soil scientist develops a concept, or model, of how they
were formed. Thus, during mapping, this model enables the soil scientist to predict
with a considerable degree of accuracy the kind of soil or miscellaneous area at a
specific location on the landscape.
Commonly, individual soils on the landscape merge into one another as their
characteristics gradually change. To construct an accurate soil map, however, soil
scientists must determine the boundaries between the soils. They can observe only
a limited number of soil profiles. Nevertheless, these observations, supplemented
by an understanding of the soil-vegetation-landscape relationship, are sufficient to
verify predictions of the kinds of soil in an area and to determine the boundaries.
Soil scientists recorded the characteristics of the soil profiles that they studied. They
noted soil color, texture, size and shape of soil aggregates, kind and amount of rock
fragments, distribution of plant roots, reaction, and other features that enable them
to identify soils. After describing the soils in the survey area and determining their
properties, the soil scientists assigned the soils to taxonomic classes (units).
Taxonomic classes are concepts. Each taxonomic class has a set of soil
characteristics with precisely defined limits. The classes are used as a basis for
comparison to classify soils systematically. Soil taxonomy, the system of taxonomic
classification used in the United States, is based mainly on the kind and character
of soil properties and the arrangement of horizons within the profile. After the soil
5
scientists classified and named the soils in the survey area, they compared the
individual soils with similar soils in the same taxonomic class in other areas so that
they could confirm data and assemble additional data based on experience and
research.
The objective of soil mapping is not to delineate pure map unit components; the
objective is to separate the landscape into landforms or landform segments that
have similar use and management requirements. Each map unit is defined by a
unique combination of soil components and/or miscellaneous areas in predictable
proportions. Some components may be highly contrasting to the other components
of the map unit. The presence of minor components in a map unit in no way
diminishes the usefulness or accuracy of the data. The delineation of such
landforms and landform segments on the map provides sufficient information for the
development of resource plans. If intensive use of small areas is planned, onsite
investigation is needed to define and locate the soils and miscellaneous areas.
Soil scientists make many field observations in the process of producing a soil map.
The frequency of observation is dependent upon several factors, including scale of
mapping, intensity of mapping, design of map units, complexity of the landscape,
and experience of the soil scientist. Observations are made to test and refine the
soil-landscape model and predictions and to verify the classification of the soils at
specific locations. Once the soil-landscape model is refined, a significantly smaller
number of measurements of individual soil properties are made and recorded.
These measurements may include field measurements, such as those for color,
depth to bedrock, and texture, and laboratory measurements, such as those for
content of sand, silt, clay, salt, and other components. Properties of each soil
typically vary from one point to another across the landscape.
Observations for map unit components are aggregated to develop ranges of
characteristics for the components. The aggregated values are presented. Direct
measurements do not exist for every property presented for every map unit
component. Values for some properties are estimated from combinations of other
properties.
While a soil survey is in progress, samples of some of the soils in the area generally
are collected for laboratory analyses and for engineering tests. Soil scientists
interpret the data from these analyses and tests as well as the field-observed
characteristics and the soil properties to determine the expected behavior of the
soils under different uses. Interpretations for all of the soils are field tested through
observation of the soils in different uses and under different levels of management.
Some interpretations are modified to fit local conditions, and some new
interpretations are developed to meet local needs. Data are assembled from other
sources, such as research information, production records, and field experience of
specialists. For example, data on crop yields under defined levels of management
are assembled from farm records and from field or plot experiments on the same
kinds of soil.
Predictions about soil behavior are based not only on soil properties but also on
such variables as climate and biological activity. Soil conditions are predictable over
long periods of time, but they are not predictable from year to year. For example,
soil scientists can predict with a fairly high degree of accuracy that a given soil will
have a high water table within certain depths in most years, but they cannot predict
that a high water table will always be at a specific level in the soil on a specific date.
After soil scientists located and identified the significant natural bodies of soil in the
survey area, they drew the boundaries of these bodies on aerial photographs and
Custom Soil Resource Report
6
identified each as a specific map unit. Aerial photographs show trees, buildings,
fields, roads, and rivers, all of which help in locating boundaries accurately.
Custom Soil Resource Report
7
Soil Map
The soil map section includes the soil map for the defined area of interest, a list of
soil map units on the map and extent of each map unit, and cartographic symbols
displayed on the map. Also presented are various metadata about data used to
produce the map, and a description of each soil map unit.
8
9
Custom Soil Resource Report
Soil Map
39616003961800396200039622003962400396260039628003963000396320039634003961600396180039620003962200396240039626003962800396300039632003963400705700 705900 706100 706300 706500 706700 706900
705700 705900 706100 706300 706500 706700 706900 707100
35° 47' 38'' N 78° 43' 29'' W35° 47' 38'' N78° 42' 30'' W35° 46' 35'' N
78° 43' 29'' W35° 46' 35'' N
78° 42' 30'' WN
Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 17N WGS84
0 450 900 1800 2700
Feet
0 100 200 400 600
Meters
Map Scale: 1:9,500 if printed on A portrait (8.5" x 11") sheet.
Soil Map may not be valid at this scale.
MAP LEGEND MAP INFORMATION
Area of Interest (AOI)
Area of Interest (AOI)
Soils
Soil Map Unit Polygons
Soil Map Unit Lines
Soil Map Unit Points
Special Point Features
Blowout
Borrow Pit
Clay Spot
Closed Depression
Gravel Pit
Gravelly Spot
Landfill
Lava Flow
Marsh or swamp
Mine or Quarry
Miscellaneous Water
Perennial Water
Rock Outcrop
Saline Spot
Sandy Spot
Severely Eroded Spot
Sinkhole
Slide or Slip
Sodic Spot
Spoil Area
Stony Spot
Very Stony Spot
Wet Spot
Other
Special Line Features
Water Features
Streams and Canals
Transportation
Rails
Interstate Highways
US Routes
Major Roads
Local Roads
Background
Aerial Photography
The soil surveys that comprise your AOI were mapped at
1:24,000.
Warning: Soil Map may not be valid at this scale.
Enlargement of maps beyond the scale of mapping can cause
misunderstanding of the detail of mapping and accuracy of soil
line placement. The maps do not show the small areas of
contrasting soils that could have been shown at a more detailed
scale.
Please rely on the bar scale on each map sheet for map
measurements.
Source of Map: Natural Resources Conservation Service
Web Soil Survey URL:
Coordinate System: Web Mercator (EPSG:3857)
Maps from the Web Soil Survey are based on the Web Mercator
projection, which preserves direction and shape but distorts
distance and area. A projection that preserves area, such as the
Albers equal-area conic projection, should be used if more
accurate calculations of distance or area are required.
This product is generated from the USDA-NRCS certified data as
of the version date(s) listed below.
Soil Survey Area: Wake County, North Carolina
Survey Area Data: Version 17, Sep 10, 2018
Soil map units are labeled (as space allows) for map scales
1:50,000 or larger.
Date(s) aerial images were photographed: Data not available.
The orthophoto or other base map on which the soil lines were
compiled and digitized probably differs from the background
imagery displayed on these maps. As a result, some minor
shifting of map unit boundaries may be evident.
Custom Soil Resource Report
10
Map Unit Legend
Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI
CfC Cecil-Urban land complex, 2 to
10 percent slopes
75.5 31.4%
ChA Chewacla and Wehadkee soils,
0 to 2 percent slopes,
frequently flooded
19.1 7.9%
PbD Pacolet-Urban land complex, 10
to 15 percent slopes
39.1 16.2%
Ur Urban land 106.9 44.4%
Totals for Area of Interest 240.6 100.0%
Map Unit Descriptions
The map units delineated on the detailed soil maps in a soil survey represent the
soils or miscellaneous areas in the survey area. The map unit descriptions, along
with the maps, can be used to determine the composition and properties of a unit.
A map unit delineation on a soil map represents an area dominated by one or more
major kinds of soil or miscellaneous areas. A map unit is identified and named
according to the taxonomic classification of the dominant soils. Within a taxonomic
class there are precisely defined limits for the properties of the soils. On the
landscape, however, the soils are natural phenomena, and they have the
characteristic variability of all natural phenomena. Thus, the range of some
observed properties may extend beyond the limits defined for a taxonomic class.
Areas of soils of a single taxonomic class rarely, if ever, can be mapped without
including areas of other taxonomic classes. Consequently, every map unit is made
up of the soils or miscellaneous areas for which it is named and some minor
components that belong to taxonomic classes other than those of the major soils.
Most minor soils have properties similar to those of the dominant soil or soils in the
map unit, and thus they do not affect use and management. These are called
noncontrasting, or similar, components. They may or may not be mentioned in a
particular map unit description. Other minor components, however, have properties
and behavioral characteristics divergent enough to affect use or to require different
management. These are called contrasting, or dissimilar, components. They
generally are in small areas and could not be mapped separately because of the
scale used. Some small areas of strongly contrasting soils or miscellaneous areas
are identified by a special symbol on the maps. If included in the database for a
given area, the contrasting minor components are identified in the map unit
descriptions along with some characteristics of each. A few areas of minor
components may not have been observed, and consequently they are not
mentioned in the descriptions, especially where the pattern was so complex that it
was impractical to make enough observations to identify all the soils and
miscellaneous areas on the landscape.
Custom Soil Resource Report
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The presence of minor components in a map unit in no way diminishes the
usefulness or accuracy of the data. The objective of mapping is not to delineate
pure taxonomic classes but rather to separate the landscape into landforms or
landform segments that have similar use and management requirements. The
delineation of such segments on the map provides sufficient information for the
development of resource plans. If intensive use of small areas is planned, however,
onsite investigation is needed to define and locate the soils and miscellaneous
areas.
An identifying symbol precedes the map unit name in the map unit descriptions.
Each description includes general facts about the unit and gives important soil
properties and qualities.
Soils that have profiles that are almost alike make up a soil series. Except for
differences in texture of the surface layer, all the soils of a series have major
horizons that are similar in composition, thickness, and arrangement.
Soils of one series can differ in texture of the surface layer, slope, stoniness,
salinity, degree of erosion, and other characteristics that affect their use. On the
basis of such differences, a soil series is divided into soil phases. Most of the areas
shown on the detailed soil maps are phases of soil series. The name of a soil phase
commonly indicates a feature that affects use or management. For example, Alpha
silt loam, 0 to 2 percent slopes, is a phase of the Alpha series.
Some map units are made up of two or more major soils or miscellaneous areas.
These map units are complexes, associations, or undifferentiated groups.
A complex consists of two or more soils or miscellaneous areas in such an intricate
pattern or in such small areas that they cannot be shown separately on the maps.
The pattern and proportion of the soils or miscellaneous areas are somewhat similar
in all areas. Alpha-Beta complex, 0 to 6 percent slopes, is an example.
An association is made up of two or more geographically associated soils or
miscellaneous areas that are shown as one unit on the maps. Because of present
or anticipated uses of the map units in the survey area, it was not considered
practical or necessary to map the soils or miscellaneous areas separately. The
pattern and relative proportion of the soils or miscellaneous areas are somewhat
similar. Alpha-Beta association, 0 to 2 percent slopes, is an example.
An undifferentiated group is made up of two or more soils or miscellaneous areas
that could be mapped individually but are mapped as one unit because similar
interpretations can be made for use and management. The pattern and proportion
of the soils or miscellaneous areas in a mapped area are not uniform. An area can
be made up of only one of the major soils or miscellaneous areas, or it can be made
up of all of them. Alpha and Beta soils, 0 to 2 percent slopes, is an example.
Some surveys include miscellaneous areas. Such areas have little or no soil
material and support little or no vegetation. Rock outcrop is an example.
Custom Soil Resource Report
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Wake County, North Carolina
CfC—Cecil-Urban land complex, 2 to 10 percent slopes
Map Unit Setting
National map unit symbol: 2xh9k
Elevation: 70 to 560 feet
Mean annual precipitation: 39 to 47 inches
Mean annual air temperature: 55 to 63 degrees F
Frost-free period: 200 to 250 days
Farmland classification: Not prime farmland
Map Unit Composition
Cecil and similar soils: 55 percent
Urban land: 35 percent
Minor components: 10 percent
Estimates are based on observations, descriptions, and transects of the mapunit.
Description of Cecil
Setting
Landform: Interfluves
Landform position (two-dimensional): Summit, shoulder
Landform position (three-dimensional): Interfluve
Down-slope shape: Convex
Across-slope shape: Convex
Parent material: Saprolite derived from granite and gneiss and/or saprolite derived
from schist
Typical profile
Ap - 0 to 8 inches: sandy loam
Bt - 8 to 42 inches: clay
BC - 42 to 50 inches: clay loam
C - 50 to 80 inches: loam
Properties and qualities
Slope: 2 to 10 percent
Depth to restrictive feature: More than 80 inches
Natural drainage class: Well drained
Capacity of the most limiting layer to transmit water (Ksat): Moderately high to
high (0.57 to 1.98 in/hr)
Depth to water table: More than 80 inches
Frequency of flooding: None
Frequency of ponding: None
Available water storage in profile: Moderate (about 7.6 inches)
Interpretive groups
Land capability classification (irrigated): None specified
Land capability classification (nonirrigated): 3e
Hydrologic Soil Group: A
Hydric soil rating: No
Description of Urban Land
Setting
Parent material: Impervious layers over human transported material
Custom Soil Resource Report
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Interpretive groups
Land capability classification (irrigated): None specified
Land capability classification (nonirrigated): 8
Hydric soil rating: No
Minor Components
Udorthents, loamy
Percent of map unit: 10 percent
Landform: Interfluves
Landform position (two-dimensional): Summit, shoulder
Landform position (three-dimensional): Interfluve
Down-slope shape: Convex
Across-slope shape: Convex
Hydric soil rating: No
ChA—Chewacla and Wehadkee soils, 0 to 2 percent slopes, frequently
flooded
Map Unit Setting
National map unit symbol: 2qwpj
Elevation: 70 to 560 feet
Mean annual precipitation: 39 to 47 inches
Mean annual air temperature: 55 to 63 degrees F
Frost-free period: 200 to 250 days
Farmland classification: Prime farmland if drained and either protected from flooding
or not frequently flooded during the growing season
Map Unit Composition
Chewacla, frequently flooded, and similar soils: 50 percent
Wehadkee, frequently flooded, and similar soils: 45 percent
Minor components: 5 percent
Estimates are based on observations, descriptions, and transects of the mapunit.
Description of Chewacla, Frequently Flooded
Setting
Landform: Flood plains
Landform position (two-dimensional): Toeslope
Landform position (three-dimensional): Dip
Down-slope shape: Concave
Across-slope shape: Linear
Parent material: Loamy alluvium derived from igneous and metamorphic rock
Typical profile
A - 0 to 4 inches: loam
Bw1 - 4 to 26 inches: silty clay loam
Bw2 - 26 to 38 inches: loam
Custom Soil Resource Report
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Bw3 - 38 to 60 inches: clay loam
C - 60 to 80 inches: loam
Properties and qualities
Slope: 0 to 2 percent
Depth to restrictive feature: More than 80 inches
Natural drainage class: Somewhat poorly drained
Capacity of the most limiting layer to transmit water (Ksat): Moderately high to
high (0.57 to 1.98 in/hr)
Depth to water table: About 6 to 24 inches
Frequency of flooding: Frequent
Frequency of ponding: None
Available water storage in profile: High (about 10.1 inches)
Interpretive groups
Land capability classification (irrigated): None specified
Land capability classification (nonirrigated): 3w
Hydrologic Soil Group: B/D
Hydric soil rating: No
Description of Wehadkee, Frequently Flooded
Setting
Landform: Flood plains
Landform position (two-dimensional): Toeslope
Landform position (three-dimensional): Dip
Down-slope shape: Concave
Across-slope shape: Linear
Parent material: Loamy alluvium derived from igneous and metamorphic rock
Typical profile
A - 0 to 7 inches: silt loam
Bg - 7 to 49 inches: clay loam
Cg - 49 to 80 inches: clay loam
Properties and qualities
Slope: 0 to 2 percent
Depth to restrictive feature: More than 80 inches
Natural drainage class: Poorly drained
Capacity of the most limiting layer to transmit water (Ksat): Moderately high to
high (0.20 to 1.98 in/hr)
Depth to water table: About 0 to 12 inches
Frequency of flooding: Frequent
Frequency of ponding: None
Available water storage in profile: High (about 11.8 inches)
Interpretive groups
Land capability classification (irrigated): None specified
Land capability classification (nonirrigated): 6w
Hydrologic Soil Group: B/D
Hydric soil rating: Yes
Minor Components
Riverview, frequently flooded
Percent of map unit: 5 percent
Landform: Flood plains
Landform position (two-dimensional): Toeslope
Custom Soil Resource Report
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Landform position (three-dimensional): Talf
Down-slope shape: Concave
Across-slope shape: Linear
Hydric soil rating: No
PbD—Pacolet-Urban land complex, 10 to 15 percent slopes
Map Unit Setting
National map unit symbol: 2xhb4
Elevation: 70 to 560 feet
Mean annual precipitation: 39 to 47 inches
Mean annual air temperature: 55 to 63 degrees F
Frost-free period: 200 to 250 days
Farmland classification: Not prime farmland
Map Unit Composition
Pacolet and similar soils: 60 percent
Urban land: 30 percent
Minor components: 10 percent
Estimates are based on observations, descriptions, and transects of the mapunit.
Description of Pacolet
Setting
Landform: Interfluves
Landform position (two-dimensional): Backslope
Landform position (three-dimensional): Side slope
Down-slope shape: Convex
Across-slope shape: Convex
Parent material: Saprolite derived from granite and gneiss and/or schist
Typical profile
Ap - 0 to 8 inches: sandy loam
Bt - 8 to 27 inches: clay
BC - 27 to 35 inches: clay loam
C - 35 to 80 inches: sandy clay loam
Properties and qualities
Slope: 10 to 15 percent
Depth to restrictive feature: More than 80 inches
Natural drainage class: Well drained
Capacity of the most limiting layer to transmit water (Ksat): Moderately high to
high (0.57 to 1.98 in/hr)
Depth to water table: More than 80 inches
Frequency of flooding: None
Frequency of ponding: None
Available water storage in profile: Moderate (about 6.3 inches)
Interpretive groups
Land capability classification (irrigated): None specified
Custom Soil Resource Report
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Land capability classification (nonirrigated): 4e
Hydrologic Soil Group: B
Hydric soil rating: No
Description of Urban Land
Setting
Parent material: Impervious layers over human transported material
Interpretive groups
Land capability classification (irrigated): None specified
Land capability classification (nonirrigated): 8
Hydric soil rating: No
Minor Components
Udorthents, loamy
Percent of map unit: 10 percent
Landform: Interfluves
Landform position (two-dimensional): Backslope
Landform position (three-dimensional): Interfluve
Down-slope shape: Convex
Across-slope shape: Convex
Hydric soil rating: No
Ur—Urban land
Map Unit Setting
National map unit symbol: 2qwpc
Elevation: 70 to 1,400 feet
Mean annual precipitation: 39 to 51 inches
Mean annual air temperature: 54 to 63 degrees F
Frost-free period: 190 to 250 days
Farmland classification: Not prime farmland
Map Unit Composition
Urban land: 100 percent
Estimates are based on observations, descriptions, and transects of the mapunit.
Description of Urban Land
Setting
Parent material: Impervious layers over human-transported material
Interpretive groups
Land capability classification (irrigated): None specified
Land capability classification (nonirrigated): 8
Hydric soil rating: No
Custom Soil Resource Report
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Custom Soil Resource Report
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Soil Information for All Uses
Soil Properties and Qualities
The Soil Properties and Qualities section includes various soil properties and
qualities displayed as thematic maps with a summary table for the soil map units in
the selected area of interest. A single value or rating for each map unit is generated
by aggregating the interpretive ratings of individual map unit components. This
aggregation process is defined for each property or quality.
Soil Qualities and Features
Soil qualities are behavior and performance attributes that are not directly
measured, but are inferred from observations of dynamic conditions and from soil
properties. Example soil qualities include natural drainage, and frost action. Soil
features are attributes that are not directly part of the soil. Example soil features
include slope and depth to restrictive layer. These features can greatly impact the
use and management of the soil.
Hydrologic Soil Group
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.
19
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.
Custom Soil Resource Report
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21
Custom Soil Resource Report
Map—Hydrologic Soil Group
39616003961800396200039622003962400396260039628003963000396320039634003961600396180039620003962200396240039626003962800396300039632003963400705700 705900 706100 706300 706500 706700 706900
705700 705900 706100 706300 706500 706700 706900 707100
35° 47' 38'' N 78° 43' 29'' W35° 47' 38'' N78° 42' 30'' W35° 46' 35'' N
78° 43' 29'' W35° 46' 35'' N
78° 42' 30'' WN
Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 17N WGS84
0 450 900 1800 2700
Feet
0 100 200 400 600
Meters
Map Scale: 1:9,500 if printed on A portrait (8.5" x 11") sheet.
Soil Map may not be valid at this scale.
MAP LEGEND MAP INFORMATION
Area of Interest (AOI)
Area of Interest (AOI)
Soils
Soil Rating Polygons
A
A/D
B
B/D
C
C/D
D
Not rated or not available
Soil Rating Lines
A
A/D
B
B/D
C
C/D
D
Not rated or not available
Soil Rating Points
A
A/D
B
B/D
C
C/D
D
Not rated or not available
Water Features
Streams and Canals
Transportation
Rails
Interstate Highways
US Routes
Major Roads
Local Roads
Background
Aerial Photography
The soil surveys that comprise your AOI were mapped at
1:24,000.
Warning: Soil Map may not be valid at this scale.
Enlargement of maps beyond the scale of mapping can cause
misunderstanding of the detail of mapping and accuracy of soil
line placement. The maps do not show the small areas of
contrasting soils that could have been shown at a more detailed
scale.
Please rely on the bar scale on each map sheet for map
measurements.
Source of Map: Natural Resources Conservation Service
Web Soil Survey URL:
Coordinate System: Web Mercator (EPSG:3857)
Maps from the Web Soil Survey are based on the Web Mercator
projection, which preserves direction and shape but distorts
distance and area. A projection that preserves area, such as the
Albers equal-area conic projection, should be used if more
accurate calculations of distance or area are required.
This product is generated from the USDA-NRCS certified data as
of the version date(s) listed below.
Soil Survey Area: Wake County, North Carolina
Survey Area Data: Version 17, Sep 10, 2018
Soil map units are labeled (as space allows) for map scales
1:50,000 or larger.
Date(s) aerial images were photographed: Data not available.
The orthophoto or other base map on which the soil lines were
compiled and digitized probably differs from the background
imagery displayed on these maps. As a result, some minor
shifting of map unit boundaries may be evident.
Custom Soil Resource Report
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Table—Hydrologic Soil Group
Map unit symbol Map unit name Rating Acres in AOI Percent of AOI
CfC Cecil-Urban land
complex, 2 to 10
percent slopes
A 75.5 31.4%
ChA Chewacla and
Wehadkee soils, 0 to 2
percent slopes,
frequently flooded
B/D 19.1 7.9%
PbD Pacolet-Urban land
complex, 10 to 15
percent slopes
B 39.1 16.2%
Ur Urban land 106.9 44.4%
Totals for Area of Interest 240.6 100.0%
Rating Options—Hydrologic Soil Group
Aggregation Method: Dominant Condition
Component Percent Cutoff: None Specified
Tie-break Rule: Higher
Custom Soil Resource Report
23
References
American Association of State Highway and Transportation Officials (AASHTO).
2004. Standard specifications for transportation materials and methods of sampling
and testing. 24th edition.
American Society for Testing and Materials (ASTM). 2005. Standard classification of
soils for engineering purposes. ASTM Standard D2487-00.
Cowardin, L.M., V. Carter, F.C. Golet, and E.T. LaRoe. 1979. Classification of
wetlands and deep-water habitats of the United States. U.S. Fish and Wildlife
Service FWS/OBS-79/31.
Federal Register. July 13, 1994. Changes in hydric soils of the United States.
Federal Register. September 18, 2002. Hydric soils of the United States.
Hurt, G.W., and L.M. Vasilas, editors. Version 6.0, 2006. Field indicators of hydric
soils in the United States.
National Research Council. 1995. Wetlands: Characteristics and boundaries.
Soil Survey Division Staff. 1993. Soil survey manual. Soil Conservation Service.
U.S. Department of Agriculture Handbook 18. http://www.nrcs.usda.gov/wps/portal/
nrcs/detail/national/soils/?cid=nrcs142p2_054262
Soil Survey Staff. 1999. Soil taxonomy: A basic system of soil classification for
making and interpreting soil surveys. 2nd edition. Natural Resources Conservation
Service, U.S. Department of Agriculture Handbook 436. http://
www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cid=nrcs142p2_053577
Soil Survey Staff. 2010. Keys to soil taxonomy. 11th edition. U.S. Department of
Agriculture, Natural Resources Conservation Service. http://
www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cid=nrcs142p2_053580
Tiner, R.W., Jr. 1985. Wetlands of Delaware. U.S. Fish and Wildlife Service and
Delaware Department of Natural Resources and Environmental Control, Wetlands
Section.
United States Army Corps of Engineers, Environmental Laboratory. 1987. Corps of
Engineers wetlands delineation manual. Waterways Experiment Station Technical
Report Y-87-1.
United States Department of Agriculture, Natural Resources Conservation Service.
National forestry manual. http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/
home/?cid=nrcs142p2_053374
United States Department of Agriculture, Natural Resources Conservation Service.
National range and pasture handbook. http://www.nrcs.usda.gov/wps/portal/nrcs/
detail/national/landuse/rangepasture/?cid=stelprdb1043084
24
United States Department of Agriculture, Natural Resources Conservation Service.
National soil survey handbook, title 430-VI. http://www.nrcs.usda.gov/wps/portal/
nrcs/detail/soils/scientists/?cid=nrcs142p2_054242
United States Department of Agriculture, Natural Resources Conservation Service.
2006. Land resource regions and major land resource areas of the United States,
the Caribbean, and the Pacific Basin. U.S. Department of Agriculture Handbook
296. http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?
cid=nrcs142p2_053624
United States Department of Agriculture, Soil Conservation Service. 1961. Land
capability classification. U.S. Department of Agriculture Handbook 210. http://
www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/nrcs142p2_052290.pdf
Custom Soil Resource Report
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APPENDIX D
STORMWATER IMPACT ANALYSIS WATERSHED MAP

STORMWATER IMPACTANALYSIS WATERSHED MAPAPPX. D10250250125SCALE: 1 INCH = 250 FEETNGROVE AVENUE STORMWATER IMPACTANALYSIS WATERSHED240.6 ACRES8.4 ACRE SITE AREA;3.5% OF CONTRIBUTINGDRAINAGE AREAWESTERN BOULEVARDJONES FRANKLIN ROAD CHAPEL HILL ROADPARCEL WITHDOCUMENTEDFLOODING

APPENDIX E
PRE- AND POST-DEVELOPMENT WATERSHED MAPS

420
43
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430440440440420430440
DATE:01-30-2020SCALE:AS SHOWNDESIGNED BY:FLMAPPROVED BY:FLMPROJECT NO.:18035ORIGINAL PLAN SIZE: 24'' X 36''© 2020 THIS DRAWING SHALL NOT BE REPRODUCED IN WHOLE OR INPART WITHOUT WRITTEN PERMISSION OF FLM ENGINEERING, INC.POST OFFICE BOX 91727RALEIGH, NORTH CAROLINA 27675PHONE: [phone]FIRM NC LICENSE NUMBER C-4222REVISION HISTORYREV#DESCRIPTIONDATEBYSHEET OF 1SCALE ADJUSTMENTTHIS BAR IS 1 INCH IN LENGTHON ORIGINAL DRAWINGIF IT IS NOT 1 INCH ON THISSHEET, ADJUST YOUR SCALEACCORDINGLY01"ISSUED FORCONSTRUCTIONSITE PERMITTING REVIEWSPR-XXXX-2020GROVE AVE SUBDIVISION738 GROVE AVERALEIGH, NC 27606PRE-DEVELOPMENTWATERSHED MAPAPPX. E1SOIL TYPESCfC - CECIL-URBAN LAND COMPLEX, 2 TO 10 PERCENT SLOPESChA - CHEWACIA AND WEHADKEE SOILS, 0 TO 3 PERCENT, FREQUENTLY FLOODEDPbD - PACOLET-URBAN LAND COMPLEX, 10 TO 15 PERCENT SLOPESCALL 48 HOURS BEFOREYOU DIGNORTH CAROLINAONE-CALL CENTER1-800-632-49490606030SCALE: 1 INCH = 60 FEETNEX. EASEMENTEX. OVERHEAD ELECTRIC LINEEX. ADJACENT OWNERSEX. PROPERTY LINEEX. STREAMEX. FENCEEX. SOIL LINEEX. STORM SEWEREX. LIDAR CONTOUR (10')EX. LIDAR CONTOUR (2')LEGENDEX. RIGHT-OF-WAYEX. STREAM BUFFEREX. WETLAND440VANN STREET40' PUBLIC R/WNEIGHBORHOOD YIELDEX. 50' NEUSERIVER BUFFEREX. STREAM(TOP OF BANK)G
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5 200+00201+00201+580+001+002+002+17 78,746 SF0.20 AC66,906 SF0.16 AC48,565 SF0.20 AC56,769 SF0.16 AC147,442 SF0.17 AC156,913 SF0.16 AC126,152 SF0.14 AC117,568 SF0.17 AC137,678 SF0.18 AC87,276 SF0.17 AC36,000 SF0.14 AC19,157 SF0.21 AC26,000 SF0.14 AC98,217 SF0.19 AC107,556 SF0.17 AC440430435440440435420425415415415415420425430
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DATE:01-30-2020SCALE:AS SHOWNDESIGNED BY:FLMAPPROVED BY:FLMPROJECT NO.:18035ORIGINAL PLAN SIZE: 24'' X 36''© 2020 THIS DRAWING SHALL NOT BE REPRODUCED IN WHOLE OR INPART WITHOUT WRITTEN PERMISSION OF FLM ENGINEERING, INC.POST OFFICE BOX 91727RALEIGH, NORTH CAROLINA 27675PHONE: [phone]FIRM NC LICENSE NUMBER C-4222REVISION HISTORYREV#DESCRIPTIONDATEBYSHEET OF 1SCALE ADJUSTMENTTHIS BAR IS 1 INCH IN LENGTHON ORIGINAL DRAWINGIF IT IS NOT 1 INCH ON THISSHEET, ADJUST YOUR SCALEACCORDINGLY01"ISSUED FORCONSTRUCTIONSITE PERMITTING REVIEWSPR-XXXX-2020GROVE AVE SUBDIVISION738 GROVE AVERALEIGH, NC 27606POST-DEVELOPMENTWATERSHED MAPAPPX. E1CALL 48 HOURS BEFOREYOU DIGNORTH CAROLINAONE-CALL CENTER1-800-632-49490404020SCALE: 1 INCH = 40 FEETNGRO
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C
A
L CAROLINA AVE60' PUBLIC R/WNEIGHBORHOODLOCALEX. SANITARYSEWER MANHOLETOP:INV IN: 426.88'INV OUT: 426.54'EX. CBINV. OUT: 440.14'EX. CBINV. IN: 439.22'INV. OUT: 439.02'EX. CBINV. IN: 433.87'INV. OUT: 433.67'EX. CBINV. IN: 433.49'INV. OUT: 433.29'EX. POWER POLE(TYP.)EX. 50' NEUSERIVER BUFFEREX. STREAMEX. WETLAND (TYP.)EX. 40' CORSS ESMTB.M. 1961, PG. 75ROAD 1ROAD 2PROP. 30' SANITARYSEWER ESMT.EX. PROPERTY LINELEGENDEX. RIGHT-OF-WAYEX. EASEMENTEX. ADJACENT OWNERSEX. ROAD CENTERLINEPROP. EASEMENT/BUFFERPROP. SETBACK LINEPROP. RIGHT-OF-WAYPROP. LOT LINESNOTES1.GRADES SHOWN REPRESENT FINISHED GRADE ELEVATIONS.2.CUT AND FILL SLOPES ARE 2H:1V UNLESS OTHERWISE NOTED.3.THE UTILITIES SHOWN ARE NOT GUARANTEED TO BE AREPRESENTATION OF ALL UTILITIES WITHIN THE PROJECTEXTENT.4.THE CONTRACTOR SHALL CALL THE NORTH CAROLINAONE-CALL-CENTER AT LEAST 48 HOURS PRIOR TO BEGINNINGWORK.5.THE CONTRACTOR SHALL VERIFY DEPTHS AND LOCATIONS OFALL UTILITIES PRIOR TO BEGINNING WORK AND SHALL USE CAREWHEN OPERATING AROUND EXISTING UTILITIES.6.THE CONTRACTOR SHALL BE FINANCIALLY RESPONSIBLE FORTHE REPAIR OF ANY EXISTING UTILITIES DAMAGED DURINGCONSTRUCTION.EX. OVERHEAD ELECTRIC LINEEX. WATER LINEEX. SANITARY SEWERPROP. WATER LINEPROP. SANITARY SEWERPROP. STORM SEWER300PROP. MAJOR CONTOUR (5')PROP. MINOR CONTOUR (1')300PROP. CURBINLET (TYP.)PROP. STORMSEWER (TYP.)PROP.SCMEX. SANITARY SEWERMAINPROP. 4.5' R/W DEDICATIONTO MEET 59' SECTIONEX. WETLANDEX. FLOOD BOUNDARY (PER FLOOD STUDY)POST-DEVELOPMENT DRAINAGE BOUNDARYDA-3 DRAINAGEAREA = 3.23 ACRESAREA TO REMAINUNDISTURBED;NOT ANALYZEDAREAS NORTHOF SITE TO BEBYPASSEDPOINT OFINTERESTEX. MAJOR CONTOUR (5')EX. MINOR CONTOUR (2')DA-5 DRAINAGEAREA = 2.64 ACRESDA-4 BYPASS DRAINAGEAREA = 2.11 ACRES (TOTAL)DA-4 BYPASS DRAINAGEAREA = 2.11 ACRES (TOTAL)DA-4 BYPASS DRAINAGEAREA = 2.11 ACRES (TOTAL)

APPENDIX F
PRE-DEVELOPMENT HYDROLOGIC MODEL

DA-1
Pre Dev
DA-2
Pre Dev Offsite
9L
Pre
Drainage Diagram for Grove_Stormwater
Prepared by FLM Engineering, Printed 1/30/2020
HydroCAD® 8.50 s/n 002245 © 2007 HydroCAD Software Solutions LLC
Subcat Reach Pond Link
Grove_Stormwater
Printed 1/30/2020Prepared by FLM Engineering
Page 2HydroCAD® 8.50 s/n 002245 © 2007 HydroCAD Software Solutions LLC
Area Listing (selected nodes)
Area
(acres)
CN Description
(subcatchment-numbers)
0.920 36 Woods, Fair, HSG A (DA-1)
1.820 39 >75% Grass cover, Good, HSG A (DA-1,DA-2)
3.110 60 Woods, Fair, HSG B (DA-1)
1.060 79 Woods, Fair, HSG D (DA-1)
1.040 98 Paved roads w/curbs & sewers (DA-1,DA-2)
7.950 TOTAL AREA
Type II 24-hr 2-Year Rainfall=3.60"Grove_Stormwater
Printed 1/30/2020Prepared by FLM Engineering
Page 3HydroCAD® 8.50 s/n 002245 © 2007 HydroCAD Software Solutions LLC
Time span=0.00-120.00 hrs, dt=0.05 hrs, 2401 points
Runoff by SCS TR-20 method, UH=SCS
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Runoff Area=5.310 ac 3.58% Impervious Runoff Depth=0.62"Subcatchment DA-1: Pre Dev
Flow Length=868' Tc=8.7 min CN=61 Runoff=4.35 cfs 0.274 af
Runoff Area=2.640 ac 32.20% Impervious Runoff Depth=0.49"Subcatchment DA-2: Pre Dev Offsite
Tc=6.0 min CN=58 Runoff=1.79 cfs 0.108 af
Inflow=6.07 cfs 0.382 afLink 9L: Pre
Primary=6.07 cfs 0.382 af
Total Runoff Area = 7.950 ac Runoff Volume = 0.382 af Average Runoff Depth = 0.58"
86.92% Pervious = 6.910 ac 13.08% Impervious = 1.040 ac
Type II 24-hr 2-Year Rainfall=3.60"Grove_Stormwater
Printed 1/30/2020Prepared by FLM Engineering
Page 4HydroCAD® 8.50 s/n 002245 © 2007 HydroCAD Software Solutions LLC
Summary for Subcatchment DA-1: Pre Dev
Runoff = 4.35 cfs @ 12.02 hrs, Volume= 0.274 af, Depth= 0.62"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs
Type II 24-hr 2-Year Rainfall=3.60"
Area (ac) CN Description
0.920 36 Woods, Fair, HSG A
3.110 60 Woods, Fair, HSG B
1.060 79 Woods, Fair, HSG D
0.190 98 Paved roads w/curbs & sewers
0.030 39 >75% Grass cover, Good, HSG A
5.310 61 Weighted Average
5.120 Pervious Area
0.190 Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
6.1 100 0.0600 0.27 Sheet Flow, Sheet Flow
Grass: Short n= 0.150 P2= 3.47"
2.1 505 0.0600 3.94 Shallow Concentrated Flow, Shallow Concentrated Flow
Unpaved Kv= 16.1 fps
0.5 263 0.0070 8.02 481.02 Channel Flow, Channel Flow
Area= 60.0 sf Perim= 22.3' r= 2.69' n= 0.030
8.7 868 Total
Subcatchment DA-1: Pre Dev
Runoff
Hydrograph
Time (hours)
1201101009080706050403020100Flow (cfs)4
3
2
1
0
Type II 24-hr 2-Year
Rainfall=3.60"
Runoff Area=5.310 ac
Runoff Volume=0.274 af
Runoff Depth=0.62"
Flow Length=868'
Tc=8.7 min
CN=61
4.35 cfs
Type II 24-hr 2-Year Rainfall=3.60"Grove_Stormwater
Printed 1/30/2020Prepared by FLM Engineering
Page 5HydroCAD® 8.50 s/n 002245 © 2007 HydroCAD Software Solutions LLC
Summary for Subcatchment DA-2: Pre Dev Offsite
Runoff = 1.79 cfs @ 12.00 hrs, Volume= 0.108 af, Depth= 0.49"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs
Type II 24-hr 2-Year Rainfall=3.60"
Area (ac) CN Description
0.850 98 Paved roads w/curbs & sewers
1.790 39 >75% Grass cover, Good, HSG A
2.640 58 Weighted Average
1.790 Pervious Area
0.850 Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
6.0 Direct Entry,
Subcatchment DA-2: Pre Dev Offsite
Runoff
Hydrograph
Time (hours)
1201101009080706050403020100Flow (cfs)2
1
0
Type II 24-hr 2-Year
Rainfall=3.60"
Runoff Area=2.640 ac
Runoff Volume=0.108 af
Runoff Depth=0.49"
Tc=6.0 min
CN=58
1.79 cfs
Type II 24-hr 2-Year Rainfall=3.60"Grove_Stormwater
Printed 1/30/2020Prepared by FLM Engineering
Page 6HydroCAD® 8.50 s/n 002245 © 2007 HydroCAD Software Solutions LLC
Summary for Link 9L: Pre
Inflow Area = 7.950 ac, 13.08% Impervious, Inflow Depth = 0.58" for 2-Year event
Inflow = 6.07 cfs @ 12.01 hrs, Volume= 0.382 af
Primary = 6.07 cfs @ 12.01 hrs, Volume= 0.382 af, Atten= 0%, Lag= 0.0 min
Primary outflow = Inflow, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs
Link 9L: Pre
Inflow
Primary
Hydrograph
Time (hours)
1201101009080706050403020100Flow (cfs)6
5
4
3
2
1
0
Inflow Area=7.950 ac
6.07 cfs6.07 cfs
Type II 24-hr 10-Year Rainfall=5.28"Grove_Stormwater
Printed 1/30/2020Prepared by FLM Engineering
Page 7HydroCAD® 8.50 s/n 002245 © 2007 HydroCAD Software Solutions LLC
Time span=0.00-120.00 hrs, dt=0.05 hrs, 2401 points
Runoff by SCS TR-20 method, UH=SCS
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Runoff Area=5.310 ac 3.58% Impervious Runoff Depth=1.54"Subcatchment DA-1: Pre Dev
Flow Length=868' Tc=8.7 min CN=61 Runoff=12.59 cfs 0.682 af
Runoff Area=2.640 ac 32.20% Impervious Runoff Depth=1.33"Subcatchment DA-2: Pre Dev Offsite
Tc=6.0 min CN=58 Runoff=5.85 cfs 0.292 af
Inflow=18.24 cfs 0.973 afLink 9L: Pre
Primary=18.24 cfs 0.973 af
Total Runoff Area = 7.950 ac Runoff Volume = 0.973 af Average Runoff Depth = 1.47"
86.92% Pervious = 6.910 ac 13.08% Impervious = 1.040 ac
Type II 24-hr 10-Year Rainfall=5.28"Grove_Stormwater
Printed 1/30/2020Prepared by FLM Engineering
Page 8HydroCAD® 8.50 s/n 002245 © 2007 HydroCAD Software Solutions LLC
Summary for Subcatchment DA-1: Pre Dev
Runoff = 12.59 cfs @ 12.01 hrs, Volume= 0.682 af, Depth= 1.54"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs
Type II 24-hr 10-Year Rainfall=5.28"
Area (ac) CN Description
0.920 36 Woods, Fair, HSG A
3.110 60 Woods, Fair, HSG B
1.060 79 Woods, Fair, HSG D
0.190 98 Paved roads w/curbs & sewers
0.030 39 >75% Grass cover, Good, HSG A
5.310 61 Weighted Average
5.120 Pervious Area
0.190 Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
6.1 100 0.0600 0.27 Sheet Flow, Sheet Flow
Grass: Short n= 0.150 P2= 3.47"
2.1 505 0.0600 3.94 Shallow Concentrated Flow, Shallow Concentrated Flow
Unpaved Kv= 16.1 fps
0.5 263 0.0070 8.02 481.02 Channel Flow, Channel Flow
Area= 60.0 sf Perim= 22.3' r= 2.69' n= 0.030
8.7 868 Total
Subcatchment DA-1: Pre Dev
Runoff
Hydrograph
Time (hours)
1201101009080706050403020100Flow (cfs)14
12
10
8
6
4
2
0
Type II 24-hr 10-Year
Rainfall=5.28"
Runoff Area=5.310 ac
Runoff Volume=0.682 af
Runoff Depth=1.54"
Flow Length=868'
Tc=8.7 min
CN=61
12.59 cfs
Type II 24-hr 10-Year Rainfall=5.28"Grove_Stormwater
Printed 1/30/2020Prepared by FLM Engineering
Page 9HydroCAD® 8.50 s/n 002245 © 2007 HydroCAD Software Solutions LLC
Summary for Subcatchment DA-2: Pre Dev Offsite
Runoff = 5.85 cfs @ 11.98 hrs, Volume= 0.292 af, Depth= 1.33"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs
Type II 24-hr 10-Year Rainfall=5.28"
Area (ac) CN Description
0.850 98 Paved roads w/curbs & sewers
1.790 39 >75% Grass cover, Good, HSG A
2.640 58 Weighted Average
1.790 Pervious Area
0.850 Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
6.0 Direct Entry,
Subcatchment DA-2: Pre Dev Offsite
Runoff
Hydrograph
Time (hours)
1201101009080706050403020100Flow (cfs)6
5
4
3
2
1
0
Type II 24-hr 10-Year
Rainfall=5.28"
Runoff Area=2.640 ac
Runoff Volume=0.292 af
Runoff Depth=1.33"
Tc=6.0 min
CN=58
5.85 cfs
Type II 24-hr 10-Year Rainfall=5.28"Grove_Stormwater
Printed 1/30/2020Prepared by FLM Engineering
Page 10HydroCAD® 8.50 s/n 002245 © 2007 HydroCAD Software Solutions LLC
Summary for Link 9L: Pre
Inflow Area = 7.950 ac, 13.08% Impervious, Inflow Depth = 1.47" for 10-Year event
Inflow = 18.24 cfs @ 12.00 hrs, Volume= 0.973 af
Primary = 18.24 cfs @ 12.00 hrs, Volume= 0.973 af, Atten= 0%, Lag= 0.0 min
Primary outflow = Inflow, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs
Link 9L: Pre
Inflow
Primary
Hydrograph
Time (hours)
1201101009080706050403020100Flow (cfs)20
18
16
14
12
10
8
6
4
2
0
Inflow Area=7.950 ac
18.24 cfs18.24 cfs

APPENDIX G
POST-DEVELOPMENT HYDROLOGIC MODEL

DA-3
Post to Pond
DA-4
Post Dev Bypass
DA-5
Post Dev Offsite to Pond
4P
Dry Detention Pond
5L
Post
Drainage Diagram for Grove_Stormwater
Prepared by FLM Engineering, Printed 1/30/2020
HydroCAD® 8.50 s/n 002245 © 2007 HydroCAD Software Solutions LLC
Subcat Reach Pond Link
Grove_Stormwater
Printed 1/30/2020Prepared by FLM Engineering
Page 2HydroCAD® 8.50 s/n 002245 © 2007 HydroCAD Software Solutions LLC
Area Listing (selected nodes)
Area
(acres)
CN Description
(subcatchment-numbers)
2.140 39 >75% Grass cover, Good, HSG A (DA-3,DA-4,DA-5)
1.790 61 >75% Grass cover, Good, HSG B (DA-3,DA-4)
0.790 79 Woods, Fair, HSG D (DA-4)
0.180 80 >75% Grass cover, Good, HSG D (DA-3)
1.870 98 Paved parking & roofs (DA-3)
1.180 98 Paved roads w/curbs & sewers (DA-4,DA-5)
7.950 TOTAL AREA
Type II 24-hr 2-Year Rainfall=3.60"Grove_Stormwater
Printed 1/30/2020Prepared by FLM Engineering
Page 3HydroCAD® 8.50 s/n 002245 © 2007 HydroCAD Software Solutions LLC
Time span=0.00-120.00 hrs, dt=0.05 hrs, 2401 points
Runoff by SCS TR-20 method, UH=SCS
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Runoff Area=3.200 ac 58.44% Impervious Runoff Depth=1.79"Subcatchment DA-3: Post to Pond
Tc=6.0 min CN=81 Runoff=9.86 cfs 0.477 af
Runoff Area=2.110 ac 15.64% Impervious Runoff Depth=1.25"Subcatchment DA-4: Post Dev Bypass
Tc=6.0 min CN=73 Runoff=4.56 cfs 0.219 af
Runoff Area=2.640 ac 32.20% Impervious Runoff Depth=0.49"Subcatchment DA-5: Post Dev Offsite to
Tc=6.0 min CN=58 Runoff=1.79 cfs 0.108 af
Peak Elev=418.08' Storage=12,293 cf Inflow=11.64 cfs 0.586 afPond 4P: Dry Detention Pond
Primary=0.80 cfs 0.585 af Secondary=0.00 cfs 0.000 af Outflow=0.80 cfs 0.585 af
Inflow=4.65 cfs 0.804 afLink 5L: Post
Primary=4.65 cfs 0.804 af
Total Runoff Area = 7.950 ac Runoff Volume = 0.805 af Average Runoff Depth = 1.22"
61.64% Pervious = 4.900 ac 38.36% Impervious = 3.050 ac
Type II 24-hr 2-Year Rainfall=3.60"Grove_Stormwater
Printed 1/30/2020Prepared by FLM Engineering
Page 4HydroCAD® 8.50 s/n 002245 © 2007 HydroCAD Software Solutions LLC
Summary for Subcatchment DA-3: Post to Pond
Runoff = 9.86 cfs @ 11.97 hrs, Volume= 0.477 af, Depth= 1.79"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs
Type II 24-hr 2-Year Rainfall=3.60"
Area (ac) CN Description
1.870 98 Paved parking & roofs
0.320 39 >75% Grass cover, Good, HSG A
0.830 61 >75% Grass cover, Good, HSG B
0.180 80 >75% Grass cover, Good, HSG D
3.200 81 Weighted Average
1.330 Pervious Area
1.870 Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
6.0 Direct Entry,
Subcatchment DA-3: Post to Pond
Runoff
Hydrograph
Time (hours)
1201101009080706050403020100Flow (cfs)11
10
9
8
7
6
5
4
3
2
1
0
Type II 24-hr 2-Year
Rainfall=3.60"
Runoff Area=3.200 ac
Runoff Volume=0.477 af
Runoff Depth=1.79"
Tc=6.0 min
CN=81
9.86 cfs
Type II 24-hr 2-Year Rainfall=3.60"Grove_Stormwater
Printed 1/30/2020Prepared by FLM Engineering
Page 5HydroCAD® 8.50 s/n 002245 © 2007 HydroCAD Software Solutions LLC
Summary for Subcatchment DA-4: Post Dev Bypass
Runoff = 4.56 cfs @ 11.98 hrs, Volume= 0.219 af, Depth= 1.25"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs
Type II 24-hr 2-Year Rainfall=3.60"
Area (ac) CN Description
0.790 79 Woods, Fair, HSG D
0.330 98 Paved roads w/curbs & sewers
0.030 39 >75% Grass cover, Good, HSG A
0.960 61 >75% Grass cover, Good, HSG B
2.110 73 Weighted Average
1.780 Pervious Area
0.330 Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
6.0 Direct Entry,
Subcatchment DA-4: Post Dev Bypass
Runoff
Hydrograph
Time (hours)
1201101009080706050403020100Flow (cfs)5
4
3
2
1
0
Type II 24-hr 2-Year
Rainfall=3.60"
Runoff Area=2.110 ac
Runoff Volume=0.219 af
Runoff Depth=1.25"
Tc=6.0 min
CN=73
4.56 cfs
Type II 24-hr 2-Year Rainfall=3.60"Grove_Stormwater
Printed 1/30/2020Prepared by FLM Engineering
Page 6HydroCAD® 8.50 s/n 002245 © 2007 HydroCAD Software Solutions LLC
Summary for Subcatchment DA-5: Post Dev Offsite to Pond
Runoff = 1.79 cfs @ 12.00 hrs, Volume= 0.108 af, Depth= 0.49"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs
Type II 24-hr 2-Year Rainfall=3.60"
Area (ac) CN Description
0.850 98 Paved roads w/curbs & sewers
1.790 39 >75% Grass cover, Good, HSG A
2.640 58 Weighted Average
1.790 Pervious Area
0.850 Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
6.0 Direct Entry,
Subcatchment DA-5: Post Dev Offsite to Pond
Runoff
Hydrograph
Time (hours)
1201101009080706050403020100Flow (cfs)2
1
0
Type II 24-hr 2-Year
Rainfall=3.60"
Runoff Area=2.640 ac
Runoff Volume=0.108 af
Runoff Depth=0.49"
Tc=6.0 min
CN=58
1.79 cfs
Type II 24-hr 2-Year Rainfall=3.60"Grove_Stormwater
Printed 1/30/2020Prepared by FLM Engineering
Page 7HydroCAD® 8.50 s/n 002245 © 2007 HydroCAD Software Solutions LLC
Summary for Pond 4P: Dry Detention Pond
Inflow Area = 5.840 ac, 46.58% Impervious, Inflow Depth = 1.20" for 2-Year event
Inflow = 11.64 cfs @ 11.98 hrs, Volume= 0.586 af
Outflow = 0.80 cfs @ 12.90 hrs, Volume= 0.585 af, Atten= 93%, Lag= 55.0 min
Primary = 0.80 cfs @ 12.90 hrs, Volume= 0.585 af
Secondary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af
Routing by Stor-Ind method, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs
Peak Elev= 418.08' @ 12.90 hrs Surf.Area= 6,881 sf Storage= 12,293 cf
Plug-Flow detention time= 661.1 min calculated for 0.585 af (100% of inflow)
Center-of-Mass det. time= 662.2 min ( 1,508.3 - 846.1 )
Volume Invert Avail.Storage Storage Description
#1 416.00' 36,768 cf Custom Stage Data (Irregular) Listed below (Recalc)
Elevation Surf.Area Perim. Inc.Store Cum.Store Wet.Area
(feet) (sq-ft) (feet) (cubic-feet) (cubic-feet) (sq-ft)
416.00 4,985 281.0 0 0 4,985
417.00 5,864 304.0 5,419 5,419 6,095
418.00 6,804 323.0 6,328 11,747 7,093
419.00 7,800 341.0 7,296 19,043 8,101
420.00 8,854 361.0 8,321 27,365 9,272
421.00 9,964 379.0 9,404 36,768 10,395
Device Routing Invert Outlet Devices
#1 Primary 416.00'18.0" x 40.0' long Culvert CMP, square edge headwall, Ke= 0.500
Outlet Invert= 415.50' S= 0.0125 '/' Cc= 0.900 n= 0.013
#2 Device 1 416.00'1.5" Vert. Orifice C= 0.600
#3 Device 1 417.25'6.0" Vert. Orifice C= 0.600
#4 Device 1 419.00'4.00' x 4.00' Horiz. Grate Limited to weir flow C= 0.600
#5 Secondary 420.00'20.0' long x 16.0' breadth Broad-Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Coef. (English) 2.68 2.70 2.70 2.64 2.63 2.64 2.64 2.63
Primary OutFlow Max=0.80 cfs @ 12.90 hrs HW=418.08' (Free Discharge)
1=Culvert (Passes 0.80 cfs of 9.81 cfs potential flow)
2=Orifice (Orifice Controls 0.08 cfs @ 6.84 fps)
3=Orifice (Orifice Controls 0.72 cfs @ 3.67 fps)
4=Grate ( Controls 0.00 cfs)
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=416.00' (Free Discharge)
5=Broad-Crested Rectangular Weir ( Controls 0.00 cfs)
Type II 24-hr 2-Year Rainfall=3.60"Grove_Stormwater
Printed 1/30/2020Prepared by FLM Engineering
Page 8HydroCAD® 8.50 s/n 002245 © 2007 HydroCAD Software Solutions LLC
Pond 4P: Dry Detention Pond
Inflow
Outflow
Primary
Secondary
Hydrograph
Time (hours)
1201101009080706050403020100Flow (cfs)12
10
8
6
4
2
0
Inflow Area=5.840 ac
Peak Elev=418.08'
Storage=12,293 cf
11.64 cfs
0.80 cfs0.80 cfs
0.00 cfs
Type II 24-hr 2-Year Rainfall=3.60"Grove_Stormwater
Printed 1/30/2020Prepared by FLM Engineering
Page 9HydroCAD® 8.50 s/n 002245 © 2007 HydroCAD Software Solutions LLC
Summary for Link 5L: Post
Inflow Area = 7.950 ac, 38.36% Impervious, Inflow Depth > 1.21" for 2-Year event
Inflow = 4.65 cfs @ 11.98 hrs, Volume= 0.804 af
Primary = 4.65 cfs @ 11.98 hrs, Volume= 0.804 af, Atten= 0%, Lag= 0.0 min
Primary outflow = Inflow, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs
Link 5L: Post
Inflow
Primary
Hydrograph
Time (hours)
1201101009080706050403020100Flow (cfs)5
4
3
2
1
0
Inflow Area=7.950 ac
4.65 cfs4.65 cfs
Type II 24-hr 10-Year Rainfall=5.28"Grove_Stormwater
Printed 1/30/2020Prepared by FLM Engineering
Page 10HydroCAD® 8.50 s/n 002245 © 2007 HydroCAD Software Solutions LLC
Time span=0.00-120.00 hrs, dt=0.05 hrs, 2401 points
Runoff by SCS TR-20 method, UH=SCS
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Runoff Area=3.200 ac 58.44% Impervious Runoff Depth=3.23"Subcatchment DA-3: Post to Pond
Tc=6.0 min CN=81 Runoff=17.54 cfs 0.862 af
Runoff Area=2.110 ac 15.64% Impervious Runoff Depth=2.50"Subcatchment DA-4: Post Dev Bypass
Tc=6.0 min CN=73 Runoff=9.10 cfs 0.440 af
Runoff Area=2.640 ac 32.20% Impervious Runoff Depth=1.33"Subcatchment DA-5: Post Dev Offsite to
Tc=6.0 min CN=58 Runoff=5.85 cfs 0.292 af
Peak Elev=419.27' Storage=21,185 cf Inflow=23.21 cfs 1.154 afPond 4P: Dry Detention Pond
Primary=8.70 cfs 1.153 af Secondary=0.00 cfs 0.000 af Outflow=8.70 cfs 1.153 af
Inflow=11.69 cfs 1.593 afLink 5L: Post
Primary=11.69 cfs 1.593 af
Total Runoff Area = 7.950 ac Runoff Volume = 1.594 af Average Runoff Depth = 2.41"
61.64% Pervious = 4.900 ac 38.36% Impervious = 3.050 ac
Type II 24-hr 10-Year Rainfall=5.28"Grove_Stormwater
Printed 1/30/2020Prepared by FLM Engineering
Page 11HydroCAD® 8.50 s/n 002245 © 2007 HydroCAD Software Solutions LLC
Summary for Subcatchment DA-3: Post to Pond
Runoff = 17.54 cfs @ 11.97 hrs, Volume= 0.862 af, Depth= 3.23"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs
Type II 24-hr 10-Year Rainfall=5.28"
Area (ac) CN Description
1.870 98 Paved parking & roofs
0.320 39 >75% Grass cover, Good, HSG A
0.830 61 >75% Grass cover, Good, HSG B
0.180 80 >75% Grass cover, Good, HSG D
3.200 81 Weighted Average
1.330 Pervious Area
1.870 Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
6.0 Direct Entry,
Subcatchment DA-3: Post to Pond
Runoff
Hydrograph
Time (hours)
1201101009080706050403020100Flow (cfs)18
16
14
12
10
8
6
4
2
0
Type II 24-hr 10-Year
Rainfall=5.28"
Runoff Area=3.200 ac
Runoff Volume=0.862 af
Runoff Depth=3.23"
Tc=6.0 min
CN=81
17.54 cfs
Type II 24-hr 10-Year Rainfall=5.28"Grove_Stormwater
Printed 1/30/2020Prepared by FLM Engineering
Page 12HydroCAD® 8.50 s/n 002245 © 2007 HydroCAD Software Solutions LLC
Summary for Subcatchment DA-4: Post Dev Bypass
Runoff = 9.10 cfs @ 11.97 hrs, Volume= 0.440 af, Depth= 2.50"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs
Type II 24-hr 10-Year Rainfall=5.28"
Area (ac) CN Description
0.790 79 Woods, Fair, HSG D
0.330 98 Paved roads w/curbs & sewers
0.030 39 >75% Grass cover, Good, HSG A
0.960 61 >75% Grass cover, Good, HSG B
2.110 73 Weighted Average
1.780 Pervious Area
0.330 Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
6.0 Direct Entry,
Subcatchment DA-4: Post Dev Bypass
Runoff
Hydrograph
Time (hours)
1201101009080706050403020100Flow (cfs)10
9
8
7
6
5
4
3
2
1
0
Type II 24-hr 10-Year
Rainfall=5.28"
Runoff Area=2.110 ac
Runoff Volume=0.440 af
Runoff Depth=2.50"
Tc=6.0 min
CN=73
9.10 cfs
Type II 24-hr 10-Year Rainfall=5.28"Grove_Stormwater
Printed 1/30/2020Prepared by FLM Engineering
Page 13HydroCAD® 8.50 s/n 002245 © 2007 HydroCAD Software Solutions LLC
Summary for Subcatchment DA-5: Post Dev Offsite to Pond
Runoff = 5.85 cfs @ 11.98 hrs, Volume= 0.292 af, Depth= 1.33"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs
Type II 24-hr 10-Year Rainfall=5.28"
Area (ac) CN Description
0.850 98 Paved roads w/curbs & sewers
1.790 39 >75% Grass cover, Good, HSG A
2.640 58 Weighted Average
1.790 Pervious Area
0.850 Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
6.0 Direct Entry,
Subcatchment DA-5: Post Dev Offsite to Pond
Runoff
Hydrograph
Time (hours)
1201101009080706050403020100Flow (cfs)6
5
4
3
2
1
0
Type II 24-hr 10-Year
Rainfall=5.28"
Runoff Area=2.640 ac
Runoff Volume=0.292 af
Runoff Depth=1.33"
Tc=6.0 min
CN=58
5.85 cfs
Type II 24-hr 10-Year Rainfall=5.28"Grove_Stormwater
Printed 1/30/2020Prepared by FLM Engineering
Page 14HydroCAD® 8.50 s/n 002245 © 2007 HydroCAD Software Solutions LLC
Summary for Pond 4P: Dry Detention Pond
Inflow Area = 5.840 ac, 46.58% Impervious, Inflow Depth = 2.37" for 10-Year event
Inflow = 23.21 cfs @ 11.97 hrs, Volume= 1.154 af
Outflow = 8.70 cfs @ 12.11 hrs, Volume= 1.153 af, Atten= 63%, Lag= 8.1 min
Primary = 8.70 cfs @ 12.11 hrs, Volume= 1.153 af
Secondary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af
Routing by Stor-Ind method, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs
Peak Elev= 419.27' @ 12.11 hrs Surf.Area= 8,078 sf Storage= 21,185 cf
Plug-Flow detention time= 402.6 min calculated for 1.153 af (100% of inflow)
Center-of-Mass det. time= 402.0 min ( 1,231.1 - 829.1 )
Volume Invert Avail.Storage Storage Description
#1 416.00' 36,768 cf Custom Stage Data (Irregular) Listed below (Recalc)
Elevation Surf.Area Perim. Inc.Store Cum.Store Wet.Area
(feet) (sq-ft) (feet) (cubic-feet) (cubic-feet) (sq-ft)
416.00 4,985 281.0 0 0 4,985
417.00 5,864 304.0 5,419 5,419 6,095
418.00 6,804 323.0 6,328 11,747 7,093
419.00 7,800 341.0 7,296 19,043 8,101
420.00 8,854 361.0 8,321 27,365 9,272
421.00 9,964 379.0 9,404 36,768 10,395
Device Routing Invert Outlet Devices
#1 Primary 416.00'18.0" x 40.0' long Culvert CMP, square edge headwall, Ke= 0.500
Outlet Invert= 415.50' S= 0.0125 '/' Cc= 0.900 n= 0.013
#2 Device 1 416.00'1.5" Vert. Orifice C= 0.600
#3 Device 1 417.25'6.0" Vert. Orifice C= 0.600
#4 Device 1 419.00'4.00' x 4.00' Horiz. Grate Limited to weir flow C= 0.600
#5 Secondary 420.00'20.0' long x 16.0' breadth Broad-Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Coef. (English) 2.68 2.70 2.70 2.64 2.63 2.64 2.64 2.63
Primary OutFlow Max=8.32 cfs @ 12.11 hrs HW=419.26' (Free Discharge)
1=Culvert (Passes 8.32 cfs of 13.48 cfs potential flow)
2=Orifice (Orifice Controls 0.11 cfs @ 8.61 fps)
3=Orifice (Orifice Controls 1.25 cfs @ 6.39 fps)
4=Grate (Weir Controls 6.96 cfs @ 1.67 fps)
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=416.00' (Free Discharge)
5=Broad-Crested Rectangular Weir ( Controls 0.00 cfs)
Type II 24-hr 10-Year Rainfall=5.28"Grove_Stormwater
Printed 1/30/2020Prepared by FLM Engineering
Page 15HydroCAD® 8.50 s/n 002245 © 2007 HydroCAD Software Solutions LLC
Pond 4P: Dry Detention Pond
Inflow
Outflow
Primary
Secondary
Hydrograph
Time (hours)
1201101009080706050403020100Flow (cfs)25
20
15
10
5
0
Inflow Area=5.840 ac
Peak Elev=419.27'
Storage=21,185 cf
23.21 cfs
8.70 cfs8.70 cfs
0.00 cfs
Type II 24-hr 10-Year Rainfall=5.28"Grove_Stormwater
Printed 1/30/2020Prepared by FLM Engineering
Page 16HydroCAD® 8.50 s/n 002245 © 2007 HydroCAD Software Solutions LLC
Summary for Link 5L: Post
Inflow Area = 7.950 ac, 38.36% Impervious, Inflow Depth = 2.40" for 10-Year event
Inflow = 11.69 cfs @ 12.08 hrs, Volume= 1.593 af
Primary = 11.69 cfs @ 12.08 hrs, Volume= 1.593 af, Atten= 0%, Lag= 0.0 min
Primary outflow = Inflow, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs
Link 5L: Post
Inflow
Primary
Hydrograph
Time (hours)
1201101009080706050403020100Flow (cfs)12
10
8
6
4
2
0
Inflow Area=7.950 ac
11.69 cfs11.69 cfs

APPENDIX H
HYDRAULIC GRADE LINE CALCULATIONS

Line Profile (Line 1) - 12-FES1
Page 1 of 1
d2p_00
422.00
419.00
416_00
413.00
410.00
0
Line 1 - 12-FE 'I
5 110 15 20 25 30 35 40 45 50
E1ev (fit)
d23_00
422.00
419.00
416.00
413.00
410.00
55 60
Reach (ft)
Invert Elevation
Depth of Flow
Hydraulic Grade Line
Velocity
Cover
Line #
Q
(cfs)
Dn Up
(ft) (ft)
Dn
(ft)
Up
(ft)
Hw
(ft)
Dn
(ft)
Up
(ft)
Jnct
(ft)
Dn
(ft/s)
Up
(ft/s)
Dn
(ft)
Up
(ft)
1
24.98
416.00
416.90
1.17
1.70
1.70
417.17
418.60
418.60
11.08
7.02
-0.93
2.16
Project File:
No. Lines: 14
Rate: 1/30/2020
Storm Sewers

Line Profile (Line 2) - 10-12
Page 1 of 1
427.00
424.00
ENKIN
4'18_00
415.00
A 2.00
0
427.00
424.00
421.00
418-00
415.00
412.00
10 20 30 40 50 60 70 80 90 100 110 120 130
Reach (ft)
Invert Elevation
Depth of Flow
Hydraulic Grade Line
Velocity
Cover
Line #
Q
(cfs)
Dn Up
(ft) (ft)
Dn
(ft)
Up
(ft)
Hw
(ft)
Dn
(ft)
Up
(ft)
Jnct
(ft)
Dn
(ft/s)
Up
(ft/s)
Dn
(ft)
Up
(ft)
2
22.32
417.00
421.90
1.60
1.68
1.68
418.60
423.58
423.58
8.28
7.91
2.56
2.25
Project File:
No. Lines: 14
Rate: 1/30/2020
Storm Sewers

Line Profile (Line 3) - 7-10
Page 1 of 1
428.00
INKIII]
422_00
40.00
A 442 M
0
5 10 15 20 25 30 35 44
428.00
426.00
424.00
422_00
4
420.00
418.00
45 50
Reach (ft)
Invert Elevation
Depth of Flow
Hydraulic Grade Line
Velocity
Cover
Line #
Q
(cfs)
Dn Up
(ft) (ft)
Dn
(ft)
Up
(ft)
Hw
(ft)
Dn
(ft)
Up
(ft)
Jnct
(ft)
Dn
(ft/s)
Up
(ft/s)
Dn
(ft)
Up
(ft)
3
20.32
422.00
422.40
1.58
1.62
1.62
423.58
424.02
424.02
7.62
7.47
2.15
3.01
Project File:
No. Lines: 14
Rate: 1/30/2020
Storm Sewers

Line Profile (Line 4) - 5-7
Page 1 of 1
429.00
427.00
425.00
423.00
421.00
429.00
427.00
425.00
5423.00
421.00
419.00 I I I I I I I I I I I I I I I I I I 419.00
0 5 10 15 20 25 30 35 40 45 50 55 O4 65 74 75 O0 85
Ready (ft)
Invert Elevation
Depth of Flow
Hydraulic Grade Line
Velocity
Cover
Line #
Q
MS)
Dn Up
(ft) (ft)
Dn
(ft)
Up
(ft)
Hw
(ft)
Dn
(ft)
Up
(ft)
Jnct
(ft)
Dn
(ft/s)
Up
(ft/s)
Dn
(ft)
Up
(ft)
4
17.30
422.50
423.90
1.52
1.50
1.50
424.02
425.40 j
425.40
6.77
6.86
2.91
2.38
Project File: No. Lines: 14
Rate: 1/30/2020
Storm Sewers

Line Profile (Line 5) - 3-5
Page 1 of 1
435.00
r �t
E. K401
423.00
420.00
0
Line 5 - 3-5 EJev (ft)
435.00
432.00
I. K4XlI'll
426.00
43.00
4,)0.00
5 10 15 20 25 30 35 40 45 50 55 6o 65 70
Reach (ft)
Invert Elevation
Depth of Flow
Hydraulic Grade Line
Velocity
Cover
Line #
Q
(cfs)
Dn Up
(ft) (ft)
Dn
(ft)
Up
(ft)
Hw
(ft)
Dn
(ft)
Up
(ft)
Jnct
(ft)
Dn
(ft/s)
Up
(ft/s)
Dn
(ft)
Up
(ft)
5
13.33
424.00
425.70
1.40
1.36
1.36
425.40
427.06 j
427.06
7.77
7.91
2.78
3.19
Project File:
No. Lines: 14
Rate: 1/30/2020
Storm Sewers

Line Profile (Line 6) - 2-3
Page 1 of 1
Line 6 - Elev (ft)
437.00
E. MIN
428.00
437.00
434.00
431.00
428_00
425.00
22 00 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 4ry ry.00
�✓/ W 0 5 10 15 20 25 30 35 40 5 60 70 75 80 LL UU
Reach (ft)
Invert Elevation
Depth of Flow
Hydraulic Grade Line
Velocity
Cover
Line #
Q
(cfs)
Dn Up
(ft) (ft)
Dn
(ft)
Up
(ft)
Hw
(ft)
Dn
(ft)
Up
(ft)
Jnct
(ft)
Dn
(ft/s)
Up
(ft/s)
Dn
(ft)
Up
(ft)
6
12.38
425.80
427.90
1.26
1.33
1.33
427.06
429.23
429.23
7.81
7.48
3.09
4.30
Project File:
No. Lines: 14
Rate: 1/30/2020
Storm Sewers

Line Profile (Line 7) - 1-2
Page 1 of 1
F CB -
Line 7 -1-
F—C@rdv(ft)
111
�����
11
{ ,, 11
�oAIli:�i
+ II 11
Invert Elevation
Depth of Flow
Hydraulic Grade Line
Velocity
Cover
Line #
Q
(cfs)
Dn Up
(ft) (ft)
Dn
(ft)
Up
(ft)
Hw
(ft)
Dn
(ft)
Up
(ft)
Jnct
(ft)
Dn
(ft/s)
Up
(ft/s)
Dn
(ft)
Up
(ft)
7
11.55
428.00
428.90
1.23
1.29
1.29
429.23
430.19
430.19
7.46
7.12
4.20
3.30
Project File:
No. Lines: 14
Rate: 1/30/2020
Storm Sewers

Line Profile (Line 8) - EX-1
Page 1 of 1
439.00
433.00
430.00
r yTy
439.00
436.00
433.00
430.00
427.00
424.00 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 424.00
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90
Reach (ft)
Line #
8
Project File:
Invert Elevation
Q Dn Up
(cfs) (ft) (ft)
10.60 429.00 433.29
Dn
(ft)
1.19
Depth of Flow
Up
(ft)
1.25
Hydraulic Grade Line
Hw Dn Up Jnct
(ft) (ft) (ft) (ft)
1.25 430.19 434.54 434.54
No. Lines: 14
Velocity Cover
Dn Up Dn Up
(ft/s) (ft/s) (ft) (ft)
7.03 6.74 3.20 3.21
Rate: 1/30/2020
Storm Sewers

Line Profile (Line 9) - 4-5
Page 1 of 1
. F
r � i ���� ��■ I I
ON
1 II II
111 III
Invert Elevation
Depth of Flow
Hydraulic Grade Line
Velocity
Cover
Line #
Q
MS)
Dn Up
(ft) (ft)
Dn
(ft)
Up
(ft)
Hw
(ft)
Dn
(ft)
Up
(ft)
Jnct
(ft)
Dn
(ft/s)
Up
(ft/s)
Dn
(ft)
Up
(ft)
9
3.02
424.00
424.90
1.25
0.70
0.70
425.40
425.60 j
425.60
2.46
4.28
3.03
2.13
Project File: No. Lines: 14
=Runate: 1/30/2020
Storm Sewers

Line Profile (Line 10) - 9-10
Page 1 of 1
Line 10 - 9-10
Elev (ft)
■
10 oil
k 11 � II
Invert Elevation
Depth of Flow
Hydraulic Grade Line
Velocity
Cover
Line #
Q
(cfs)
Dn Up
(ft) (ft)
Dn
(ft)
Up
(ft)
Hw
(ft)
Dn
(ft)
Up
(ft)
Jnct
(ft)
Dn
(ft/s)
Up
(ft/s)
Dn
(ft)
Up
(ft)
10
1.53
422.00
422.75
1.25
0.83
0.88
423.58
423.58
423.63
1.25
1.77
2.90
2.15
Project File:
No. Lines: 14
Rate: 1/30/2020
Storm Sewers

Line Profile (Line 11) - 8-9
Page 1 of 1
429.00
427_00
425.00
423_ DD
421.00
419.00
0
5 10 15 20 25 30 35 40 45 50
429.00
427.00
425.00
423.00
421.00
419.00
55 60
Reach (ft)
Invert Elevation
Depth of Flow
Hydraulic Grade Line
Velocity
Cover
Line #
Q
MS)
Dn Up
(ft) (ft)
Dn
(ft)
Up
(ft)
Hw
(ft)
Dn
(ft)
Up
(ft)
Jnct
(ft)
Dn
(ft/s)
Up
(ft/s)
Dn
(ft)
Up
(ft)
11
1.12
422.85
425.00
0.78
0.42
0.42
423.63
425.42 j
425.42
1.39
3.13
2.05
2.36
Project File: No. Lines: 14
Rate: 1/30/2020
Storm Sewers

Line Profile (Line 12) - 6-7
Page 1 of 1
Line 1 - 6-7 EJev (it)
429.00 429.00
427_ 427.00
425.00 425.00
............. ............... .......................................... ......................................... ......................................... ......................... .................
...........
43-00 423.00
One J
421.00 421.00
419.00 419.00
0 5 10 15 20 25 30 35 40
Reach (ft)
Invert Elevation
Depth of Flow
Hydraulic Grade Line
Velocity
Cover
Line #
Q
(cfs)
Dn Up
(ft) (ft)
Dn
(ft)
Up
(ft)
Hw
(ft)
Dn
(ft)
Up
(ft)
Jnct
(ft)
Dn
(ft/s)
Up
(ft/s)
Dn
(ft)
Up
(ft)
12
2.55
422.50
423.00
1.25
1.04
1.13
424.02
424.04
424.13
2.08
2.33
3.66
3.16
Project File:
No. Lines: 14
Rate: 1/30/2020
Storm Sewers

Line Profile (Line 13) - 11-12
Page 1 of 1
Invert Elevation
Depth of Flow
Hydraulic Grade Line
Velocity
Cover
Line #
Q
(cfs)
Dn Up
(ft) (ft)
Dn
(ft)
Up
(ft)
Hw
(ft)
Dn
(ft)
Up
(ft)
Jnct
(ft)
Dn
(ft/s)
Up
(ft/s)
Dn
(ft)
Up
(ft)
13
1.48
417.00
417.40
1.25
1.23
1.25
418.60
418.63
418.65
1.21
1.21
3.31
2.91
Project File:
No. Lines: 14
Run Date: 1/30/2020
Storm Sewers

Line Profile (Line 14) - Pipe - (25)
Page 1 of 1
Line 14 - Pipe - (5) Elev (ft)
432.00
INKIIII
420-00
416.00
432.00
428.00
424.00
424.00
416.00
412.00 I I I I I I I I I I I I I I I I I I 412.00
0 10 20 30 40 50 60 70 30 90 100 110 120 130 140 150 160 170
Reach (ft)
Line #
14
Project File:
Invert Elevation
Q Dn Up
(cfs) (ft) (ft)
35.54 420.00 423.00
Dn
(ft)
1.40
Depth of Flow
Up
(ft)
2.02
Hw
(ft)
2.02
Hydraulic Grade Line Velocity Cover
Dn Up Jnct Dn Up Dn Up
(ft) (ft) (ft) (ft/s) (ft/s) (ft) (ft)
421.40 425.02 425.02 12.59 8.36 -2.50 2.50
No. Lines: 14 Rate: 1/30/2020
Storm Sewers

APPENDIX I
NUTRIENT CALCULATIONS

January 15, 2020
Nitrogen Calculations
738 Grove Ave
Existing
Proposed without controls
Type of Land Cover Site Area (ac)
TN Export Coeff.
(lbs/ac/yr)
TN Export by Land
Use (lbs/yr)
TN Export From Site
(lbs/ac/yr)
Permanently preserved undisturbed open space
(forest, unmown meadow)8.430 0.60 5.06
0.60
0.000 21.20
Permanently preserved managed open space
(grass, landscaping, etc.)0.000 1.20 0.00
Impervious surfaces 0.00
0.88 0.60 0.53
Total 8.43 5.06
Average for Site
2.01 21.20 42.61
Type of Land Cover Site Area (ac)
TN Export Coeff.
(lbs/ac/yr)
TN Export by Land
Use (lbs/yr)
TN Export From Site
(lbs/ac/yr)
Permanently preserved undisturbed open space
(forest, unmown meadow)
5.91
Permanently preserved managed open space
(grass, landscaping, etc.)5.54 1.20 6.65
Impervious surfaces
Total 8.43 49.79
Average for Site
PO Box 91727, Raleigh, NC 27675 p | 919.423.8975

APPENDIX J
OPERATIONS AND MAINTENANCE MANUAL

The BMP(s) on this project include (check all that apply & corresponding O&M tables will be added automatically):
Quantity: Location(s):
Quantity: 1 Location(s):
Quantity: Location(s):
Quantity: Location(s):
Quantity: Location(s):
Quantity: Location(s):
Quantity: Location(s):
Quantity: Location(s):
Quantity: Location(s):
Quantity: Location(s):
Quantity: Location(s):
Quantity: Location(s):
Quantity: Location(s):
Present: No Location(s):
Present: No Location(s):
I, , a Notary Public for the State of
County of , do hearby certify that
personally appeared before me this day of and
acknowledge the due execution of the Operations and Maintenance Agreement .
Witness my hand and official seal, _____________________________________________.
Seal
Project Name:
Project Location:
Grove Ave Subdivison
Raleigh
Operation & Maintenance Agreement
Date:
Proprietary System
Rainwater Harvesting
Sand Filter
* Responsible Party:
Title & Organization:
Stormwater Wetland
Wet Detention Basin
Disconnected Impervious Area
Cary, NC 27511
336-740-4401
[e-mail]
I acknowledge and agree by my signature below that I am responsible for the performance of the maintenance procedures listed
for each BMP above, and attached O&M tables. I agree to notify NCDENR of any problems with the system or prior to any
changes to the system or responsible party.
Phone number(s):
Email:
Signature:
Street address:
City, state, zip:
Grassed Swale
Infiltration Basin
Infiltration Trench
Green Roof
Permeable Pavement
Level Spreader/VFS
A-Squared, LLC
51 Kilmayne Dr, Suite 100
My commission expires
User Defined BMP
Maintenance records shall be kept on the following BMP(s). This maintenance record shall be kept in a log in a known set
location. Any deficient BMP elements noted in the inspection will be corrected, repaired, or replaced immediately. These
deficiencies can affect the integrity of structures, safety of the public, and the pollutant removal efficiency of the BMP(s).
End or proposed cul-de-sac
Bioretention Cell
Dry Detention Basin
Cover Page
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Stone verge is clogged or
covered in sediment (if
applicable).
Remove sediment and replace with clean stone.
The forebay Trash/debris is present. Remove the trash/debris.
Erosion has occurred or
riprap is displaced.
Provide additional erosion protection such as reinforced turf matting or
riprap if needed to prevent future erosion problems.
Weeds are present. Remove the weeds, preferably by hand. If pesticides are used, wipe
them on the plants rather than spraying.
Vegetation is too short or too
long.
Maintain vegetation at a height of approximately six inches.
The inlet device The pipe is clogged. Unclog the pipe. Dispose of the sediment off-site.
The pipe is cracked or
otherwise damaged.
Replace the pipe.
Erosion is occurring in the
swale.
Regrade the swale if necessary to smooth it over and provide erosion
control devices such as reinforced turf matting or riprap to avoid future
problems with erosion.
The entire BMP Trash/debris is present. Remove the trash/debris.
The perimeter of the BMP Areas of bare soil and/or
erosive gullies have formed.
Regrade the soil if necessary to remove the gully, and then plant a
ground cover and water until it is established. Provide lime and a one-
time fertilizer application.
If cracks, seepage, or woody vegetation is present, consult a dam safety expert for a dam inspection.
The measuring device used to determine the sediment elevation shall be such that it will give an accurate depth reading and not
readily penetrate into accumulated sediments.
After the dry detention basin is established, it will be inspected quarterly. Inspection activities shall be performed as follows and
any problems identified will be remediated immediately per the table below.
BMP element: Potential problem: How to remediate the problem:
Immediately after the dry extended detention basin is established, the vegetation will be watered twice weekly if needed
until the plants become established (commonly six weeks).
No portion of the dry extended detention pond will be fertilized after the first initial fertilization that is required to establish
the vegetation.
The vegetation in and around the basin will be maintained at a height of approximately six inches.
Important maintenance procedures:
The drainage area will be managed to reduce the sediment load to the dry extended detention basin.
Dry Detention Pond Maintenance Requirements
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BMP element:
Dry Detention Pond Maintenance Requirements (continued)
The receiving water Erosion or other signs of
damage have occurred at the
outlet.
Contact the local NC Department of Environment and Natural
Resources Regional Office.
The embankment Shrubs or trees have started
to grow on the embankment.
Remove shrubs or trees immediately.
Signs of seepage on the
downstream face.
Consult a professional.
Make all needed repairs.An annual inspection by an
appropriate professional
shows that the embankment
needs repair.
The main treatment area Sediment has accumulated
and reduced the depth to
75% of the original design
depth (per pond design data
sheet)
Search for the source of the sediment and remedy the problem if
possible. Remove the sediment and dispose of it in a location where
it will not cause impacts to streams or the BMP. Revegetate disturbed
areas immediately with sod (preferred) or seed protected with securely
staked erosion mat.
Water is standing more than
5 days after a storm event.
Check outlet structure for clogging. If it is a design issue, consult an
appropriate professional.
Clean out the outlet device. Dispose of the sediment off-site.The outlet device Clogging has occurred.
The outlet device is damaged Repair or replace the outlet device.
Potential problem: How to remediate the problem:
Evidence of muskrat or
beaver activity is present.
Use traps to remove muskrats and consult a professional to remove
beavers.
Weeds and noxious plants
are growing in the main
treatment area.
Remove the plants by hand or by wiping them with pesticide (do not
spray).
Grass cover is unhealthy or
eroding.
Restore the health of the grass cover – consult a professional if
necessary.
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Dry Pond Diagram
419
03
Yes 416
No 415.5

Pretreatment
Has Veg. Filter
Dry Pond 1
DRY POND ID
Sediment Storage El:
Bottom Elevation:
Sediment Storage El:
Bottom Elevation:
MAIN POND
Dry Detention Pond Design Summary
Temporary Pool El:
Clean Out Depth:
Temporary Pool El:
Clean Out Depth:
FOREBAY
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