NCG140463_Raleigh Concrete LLC NOI_20180626

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PABST DESIGN GROLIP, PA
l\ (� 1\ 1 I I� 1\ G & C. O\-SH L I I\("
LETTER OF TRANSMITTAL
To: NCDEQ
DEMLR — Stormwater Program
Department of Environmental Quality
1612 Mail Service Center
Raleigh, NC 27699-1612
Re: 1938 S. Wilmington St.
NCG14000 N.O.I.
am sending you the following item(s):
911 Paverstone Drive, Ste. E
Raleigh, NC 27615
Office: 919.848.4399
Fax: [phone]
Date: 06/26/18
Job No.: 339-16
COPIES
DATE
NO.
DESCRIPTION
1
6/26/18
1
NCG140000 Application
1
6/26/18
2
$100 Application Fee Check
2
6/9/17
3
Approved Plot Plan (w/in Approved Structural Construction Document
Set) — 24" x 36", two (2) copies
1
12/13/16
4
Approved Stormwater Impact Analysis (associated with Approved Plot
Plan)
1
6/26/18
6
Narrative of Operations
These are transmitted as checked below:
❑ As requested
❑ For approval
❑ For review and comment
Remarks:
Please let me know if you need any other information.
Copy to: File
❑ For your use
❑ For Signatures R�CiEF/�
�O
® For Submittal JUN 2 8 ?018
srO�Nw,- IAAIDp°UAur>'
Signed:
Samantha Brothers

Raleigh Concrete, LLC
Ready -Mix Concrete Batch Plan
NCG140000 N.O.I.
Narrative of Plant Operation
Waste Sources
The following is a narrative description and identification of each type of process, operation, or production area that
takes place at existing ready -mix concrete batch plant and how those activities might contribute fluid or solid waste.
The plant is in Raleigh, North Carolina at address 1938 South Wilmington Street.
The site consists of a mobile ready -mix batch plant, located towards the rear -center of the property. The mobile
plant is CON -E -CO LO -PRO 327 series and operates as a dry -mix concrete plant. To the south of the plant, in the rear
corner of the property, is a permanent truck wash station and pump house. Fluid and solid wastes are created on
site during typical plant operations. Sources of waste water include vehicle and equipment cleaning, mixing drum
cleaning, and stormwater runoff. Sources of solid waste include excess concrete from trucks returning to the site to
be emptied.
Fluid Waste Management
Mixer trucks enter the site from the driveway access on South Wilmington Street and pull up to the batch plant to
receive automatically weighed materials and water. The trucks then drive to the permanent wash station to be rinsed
before exiting the site. Alternatively, mixer trucks enter the site from the driveway access on South Wilmington
Street and pull to the permanent truck wash station to be rinsed. In both cases, the washing of trucks is producing
waste water. All runoff from this process is collected in the wash station. The wash station contains a series of three
settling tanks. The water is then pumped from the third, and final settling tank, to be recycled for future concrete
mixes on site.
The permanent truck wash station will not discharge any wastewater from the washing of the trucks. This plant is a
relatively small operation, with limited truck washes daily. The only stormwater that is retained by the wash pit is
that which falls in the immediate surrounding area. All other stormwater runoff onsite is directed around the wash
pit. The wash pit is sized to retain necessary wastewater and stormwater that drains to it.
Solid Waste Management
Mixer trucks that arrive on site with any excess or improperly mixed concrete will be emptied and cleaned on site.
All trucks will be emptied and cleaned within the truck wash station to ensure all wastewater is contained in the
wash pit. All excess concrete will be set aside, typically in a mold, to cure and be used as recycled aggregate.
To review, there is no discharge of wastewater from the site. Nor is there any disposal of solid or fluid wastes from
the site. The only wastewater produced onsite is from the washing of mixer trucks. This wastewater enters the wash
station and is processed through a series of settling tanks and later recycled for use on the plant. All stormwater
leaving the site has no contact with the wastewater produced in the operation of the plant. Approved site plan
includes a Stormwater Impact Analysis that further details the impacts the plant has on stormwater and the
surrounding area.

rnv rollfTwnfal
- Quality
NOTICE OF INTENT
DECEIVED
JUN 2 6 2018
Division of EW.d Land Resources
STQdYi171mination
National Pollutant DischargSystem
NCG140
FOR AGENCY USE ONLY
Date Received
Year
Month Da
Telephone No. 919 859-0201
Email [e-mail]
Certificate of Coverage
Chrck # LAirnottut
Pen& Ass ed to
Alternate Contact Telephone (if different) 919.339.8663
Vi C6-,) Y 0 Y �-3
National Pollutant Discharge Elimination System application for coverage under General Permit NCG140000:
STORMWATER AND PROCESS WASTEWATER DISCHARGES associated with activities classified as:
SIC (Standard Industrial Classification) Code: 3273 and like activities
Ready Mixed Concrete
This NOI may be an application to discharge process wastewater. NCG140000 contains effluent limitations
for process wastewater discharges. Wastewater discharges must meet the requirements of these effluent
limitations. An exceedance of any of these limitations will result in a violation of the permit conditions.
For questions, contact the DEMLR Central Office or Regional Office in your area. (See page 8)
1)
(Please print or type)
Mailing address of owner/operator (official address to which all permit correspondence will be
mailed):
Legal Company Name RAELIGH CONCRETE LLC
(Please attach the most recent Annual Report to the NC Secretary of State showing the current legal name. Alternatively
this permit can be given to an individual.)
Signee's Name (as signed for in question 28 below) JOSE JUAN PLASCENCIA
Street Address 1938 South Wilmington St
City RALEIGH
State NC ZIP Code 27607
Telephone No. 919 859-0201
Email [e-mail]
Alternate ContactName BRENDA ROQUE
Email (if different)
Alternate Contact Telephone (if different) 919.339.8663
2) Location of facility producing discharge:
Facility Name RALEIGH CONCRETE
Street Address 1938 S WILMINGTON ST
City RALEIGH
State NC ZIP Code 27603
County Facility WAKE
Contact BRENDA ROQUE
Telephone No. 919 339.8663
Email BRENDA. ROQUE(aD-RALEIGHCOb
3) Physical location information:
Please provide narrative directions to the facility (use
street names, state road numbers, and distance and
direction from a roadway intersection). EXIT 2988 oft of 1-40 (Raleigh Beitline), Left of S Saunder St, Left on Penmarc or, keep straight on water works St,
Left on Favetteville St Left of South wilmington
and destination if on the right.
(A copy of a county map or USGS quad sheet with facility clearly located on the map is a required part of this application.)
4) Latitude 35.754982 Longitude -78.6446137 (deg., min, sec or decimal)
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NCG140000 N.O.I.
5) This NPDES Permit Application applies to the following (check all that apply):
❑ New or Proposed Facility Date operation is to begin
IN Existing Facility Date operation began 09/01/2017
6) Consultant's application information:
Consultant: DAN PABST, PE
Consulting Firm: PABST DESIGN GROUP, PA
Mailing Address: 911 PAVERSTONE DRIVE STE. E
City: RALEIGH
State: Nc Zip Code: 27815
Phone:(919 ) 848.4399
Email: [e-mail]
(Optional)
Staple Business Card Here:
7) Provide the 4 digit Standard Industrial Classification Code (SIC Code) that describes the primary
industrial activity at this facility:
SIC Code: 3 2 7 3
8) Provide a brief description of the types of industrial activities and products produced at this facility:
(Attach a site diagram showing the process areas present at this facility.)
READY -MIX CONCRETE
Stormwater Discharge, Wastewater Treatment & Discharge and Permitting Information
9) Discharge points / Receiving waters:
What is the name of the body or bodies of water (creek, stream, river, lake, etc.) that the facility stormwater
and/or wastewater discharges will end up in? WALNUT CREEK
To find the waterbody, please see the NC Surface Waterbody Classifications map at
https: //deq. n c.gov/a bout/divi s i ons/water-resources/water-resou rces-science-data
Receiving water classification (s) for the waters: C;NSW
If the site will discharge to a separate storm sewer system, name the operator of the separate storm sewer
system (e.g. City of Raleigh municipal storm sewer). CITY OF RALEIGH
Page 2 of 8
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NCG140000 N.O.I.
List discharge points (outfalls) that convey discharge from the site (both on-site and off-site) and location
coordinates. Attach additional sheets if necessary, or note that this information is specified on the site plan.
Be sure to indicate a type for each outfall listed below as Stormwater only, Wastewater only or Wastewater
Commingled with Stormwater
Outfall No. 1StormAr onl ❑✓ Wastewater only
Latitude (degrees/minutes/seconds): 21063322.0341
Longitude (degrees/minutes/seconds): 729882.6657
Outfall No. Stonnwater only
Latitude (degrees/minutes/seconds):
Longitude (degrees/minutes/seconds):
Outfall No. Stormwater only
Latitude (degrees/minutes/seconds):
Longitude (degrees/minutes/seconds):
Outfall No. Stormwater only
Latitude (degrees/minutes/seconds):
Longitude (degrees/minutes/seconds):
Outfall No. Stormwater only
Latitude (degrees/minutes/seconds):
Longitude (degrees/minutes/seconds):
Outfall No. Stormwater only
Latitude (degrees/minutes/seconds):
Longitude (degrees/minutes/seconds):
Outfall No. Stormwater only
Latitude (degrees/minutes/seconds):
Longitude (degrees/minutes/seconds):
❑ Wastewater only
❑ Wastewater only
❑ Wastewater only
❑ Wastewater only
❑ Wastewater only
❑ Wastewater only
_ N
W
_ N
W
_ N
W
_ N
W
_ N
W
_ N
W
_ N
W
Wastewater Commingled with Stormwater
Wastewater Commingled with Stormwater
Wastewater Commingled with Stormwater
Wastewater Commingled with Stormwater
Wastewater Commingled with Stormwater
Wastewater Commingled with Stormwater
Wastewater Commingled with Stormwater
Will this facility discharge wastewater to SA (Shellfish) waters? O Yes allo
Note: Discharge of process wastewater to receiving waters classified as Critical Area (CA) must be
reviewed by the N.C. Division of Water Resources, Public Water Supply Section ahead of
approval. No new discharges of process wastewater are permitted in receiving waters
classified as WS -1 or freshwater ORW.
You must show all discharge points clearly on the submitted site plan. Be advised that
NCDEQ may require you to apply for an individual permit, based on proposed discharge rates
and receiving stream conditions (low flows, impairments, etc.)
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NCG140000 N.O.I.
10) Each applicant shall provide the following information (attach additional sheets as necessary):
• Two (2) site plans depicting the facility or site with numbered outfalls which indicate stormwater and
wastewater outfalls. The plans shall legibly show. at a minimum, (existing or proposed):
o Outline of drainage areas with topographical lines and features
o Stormwater/wastewater treatment structures
o Location of numbered stormwater/wastewater outfalls (corresponding to which drainage areas)
o Runoff conveyance structures
o Areas and acreage where materials are stored
o Impervious area acreages
o Location(s) of streams and/or wetlands the site is draining to, and any applicable buffers
o Site property lines, North Arrow, and bar scale
o If applicable, the 100 -year floodplain line
o Acreage of each stormwater and wastewater topographical area
o Each of the facilities' wastewater or stormwater source and discharge structures and each of its
hazardous waste treatment, storage, or disposal facilities
o Site location (insert)
Site plans shall be 24" x 36" in size.
• Line drawing and description: A line drawing of the water flow through the facility. A pictorial description
of the nature and amount of any sources of water and any collection and treatment measures.
• A narrative description and identification of each type of process, operation, or production area which
contributes wastewater to the effluent for each outfall, and a description of the treatment the wastewater
receives (or will receive), including the ultimate disposal of any solid or fluid wastes other than by
discharge. Processes, operations, or production areas may be described in general terms (e.g. "ash
silo").
11) Does the applicant have any unresolved Notice of Violations (NOVs)?
IN No ❑ Yes
Wastewater:
12) What types of wastewater does your facility generate or discharge?
Type of Authorized Wastewater
Generate
Discharge
Sent to WW'
Treatment
System
Vehicle and equipment cleanin VE
0
❑
❑
Wetting of raw material stockpiles RM
❑
❑
❑
Mixing drum cleaning MD
O
❑
❑
Further explanation, if necessary: WATER GENERATED BY VEHICLES/EQUIPMENT CLEANING IS CHEMICAL FREE AND IS THEN RECYCLED FOR
USE OF THE MANUFACTURING OF READY MIX CONCRETE
13) Will your facility spray -down or actively wet aggregate piles?
IN No ❑ Yes
14) Does the facility use any of the following on site?
❑ Phosphorus -containing Detergents
❑ Brighteners ❑ Other Cleaning Agents
❑ Non -Phosphorus -containing Detergents
❑ Other:
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NCG140000 N.O.I.
15) Are wastewater treatment facilities planned in the 100 -year flood plain?
0 No ❑ Yes
WC16) Will your facility build a closed-loop recycle system (CLRSs) that meets design requirements in 15A
NCAC 02T.1000 and hold your facilities' working volume'?
❑ Yes ❑� No
If Yes, STOP COMPLETION of this permit. Contact DWR Non -Discharge Permitting Program for permitting
requirements.
17) A wastewater treatment alternatives review is required by 15A NCAC 2H.0105 (c)(2) for any new or
expanding water pollution control facility's discharge in North Carolina. You may attach additional sheets.
a) What wastewaters were considered for this alternatives review? ❑ VE ❑ RM ❑ MD
b) Connection to a Municipal or Regional Sewer Collection System:
i) Are there existing sewer lines within a one -mile radius?„ ..................................... ❑ Yes ® No
(1) If Yes, will the wastewater treatment plant (WWTP) accept the wastewater? .... ❑ Yes ❑ No
(a) If No, please attach a letter documenting that the WWTP will not accept the wastewater.
(b) If Yes, is it feasible to connect to the WWTP? Why or why not?*
c) Surface or Subsurface Disposal System (e.g., spray irrigation):
i) Is a surface or subsurface disposal technologically feasible (possible)? ....................❑ Yes ❑ No
Why or Why not?
ii) Is a surface or subsurface disposal system feasible to implement?* ........................... ❑ Yes ❑ No
Why or Why not?
iii) What is the feasibility of employing a subsurface or surface discharge as compared to a direct
discharge to surface waters?*
d) Direct Discharge to Surface Waters: Is discharge to surface waters the most environmentally sound
alternative of all reasonably cost-effective options of the wastewaters being considered?*... ❑ Yes ❑ No
i) If No, contact DEMLR's Land Application Unit to determine permitting requirements.
e) If this review included all wastewater discharge types, would excluding some types (e.g. raw
stockpile wetting) make any of the above non -discharge options feasible? ..............❑ Yes ❑ No
" You may be asked to provide further information to support your answers to these questions after the initial review.
Feasibility should take into account initial and recurring costs.
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NCG140000 N.O.I.
Stormwater:
18) Does this facility employ any best management practices for Stormwater control? I] No ❑ Yes
If yes, please briefly describe:
19) Does this facility have a Stormwater Pollution Prevention Plan? p No ❑ Yes
If yes, when was it implemented?
20) Are vehicle maintenance activities (VMA) occurring or planned at this facility? p No ❑Yes
If yes, does your VMA area discharge into your wastewater treatment device? ❑ No ❑ Yes
Other/Permitting:
21) Does this facility have a Division of Land Resources Erosion & Sedimentation Control (E&SC) Permit?
0 No ❑ Yes
If yes, list the permit numbers for all current E&SC permits for this facility:
22) Is your facility subject to Phase II Post -Construction Area? p No ❑ Yes
If yes, who is the permitting authority?
23) Is your facility located in one of the 20 Coastal Counties? ❑ Yes [D No
Is your facility adding more than 10,000 ft2 of built -upon area or CAMA Major Permit? ❑ Yes E]No
24) Is your facility discharging wastewater (treated or untreated) such as water from wetting of aggregate piles, drum
rinse -out, or vehicle and equipment cleaning to a stormwater BMP? ED No ❑ Yes
If yes, please attach your approval from the permitting authority to do so.
25) Does this facility have any other NPDES permits? p No ❑ Yes
If yes, list the permit numbers for all current NPDES permits for this facility:
26) Does this facility have any Non -Discharge permits (ex: recycle permits)? 0 No ❑ Yes
If yes, list the permit numbers for all current Non -Discharge permits for this facility:
27) Hazardous Waste:
a) Is this facility a Hazardous Waste Treatment, Storage, or Disposal Facility?
❑✓ No ❑ Yes
b) Is this facility a Small Quantity Generator (less than 1000 kg. of hazardous waste generated per month) of
hazardous waste?
ED No ❑Yes
c) Is this facility a Large Quantity Generator (1000 kg. or more of hazardous waste generated per month) of
hazardous waste?
R✓ No ❑ Yes
d) Type(s) of waste:
How is material stored: "I"
Where is material stored:
Page 6 of 8
SWU-NCG14-NOI
Last revised 8/01/2017

NCG140000 N.O.I.
How many disposal shipments per year. "'^ _
Name of transport / disposal vendor:
Vendor address: "'^
Final Checklist
This application will be returned as incomplete unless all of the following items have been included:
© Check for $100 made payable to NCDEQ.
RAJ This completed application and all supporting documentation. See Question 10.
11� ❑ If an Erosion & Sedimentation Control (E&SC) Plan is required from Division of Land Resources (DLR) or
local designee: documentation verifying applicant has developed and submitted that Plan to the governing
agency (required per 15A NCAC 02H .0138).
—I 0 Two (2) site plans depicting the site plan with numbered outfalls which indicate stormwater and wastewater
t outfalls. See Question 10.
R1 A county map or USGS quad sheet with location of facility clearly marked.
28) Signatory Requirements (per 40 CFR 122.22)
All applications, reports, or information submitted to the Director shall be signed and certified.
a. All notices of intent to be covered under this General Permit shall be signed as follows:
(1) For a corporation: by a responsible corporate officer. For the purpose of this permit, a responsible corporate officer means: (a) a
president, secretary, treasurer or vice president of the corporation in charge of a principal business function, or any other person who
performs similar policy or decision making functions for the corporation, or (b) the manager of one or more manufacturing production or
operating facilities employing more than 250 persons or having gross annual sales or expenditures exceeding 25 million (in second quarter
1980 dollars), if authority to sign documents has been assigned or delegated to the manager in accordance with corporate procedures.
(2) For a partnership or sole proprietorship: by a general partner or the proprietor, respectively; or
(3) For a municipality, state, federal, or other public agency: by either a principal executive officer or ranking elected
official.
Certification: North Carolina General Statute 143-215.6 B(i) provides that:
Any person who knowingly makes any false statement, representation, or certification in any application, record, report, plan, or other
document filed or required to be maintained under this Article or a rule implementing this Article; or who knowingly makes a false statement of
a material fact in a rulemaking proceeding or contested case under this Article, or who falsifies, tampers with, or knowingly renders inaccurate
any recording or monitoring device or method required to be operated or maintained under this Article or rules of the [Environmental
Management] Commission implementing this Article shall be guilty of a Class 2 misdemeanor which may include a fine not to exceed ten
thousand dollars ($10,000).
I hereby request coverage under the referenced General Permit. I understand that coverage under this permit will
constitute the permit requirements for the discharge(s) and is enforceable in the same manner as an individual
permit.
I certify that I am familiar with the information contained in this application and that to the best of my knowledge
and belief such information is true, complete, and accur
Printed Name of Person Signing: �:S®-�,��_cs
Title: f)Lj
re of Applicant)
� I Z5)/&--
(Date Signed)
Page 7 of 8
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NCG 140000 N.O.I.
Notice of Intent must be accompanied by a check or money order for $100.00 made payable to: NCDEQ
Mail the entire package to:
DEMLR - Stormwater Program
Dept. of Environmental Quality
1612 Mail Service Center
Raleigh, North Carolina 27699-1612
Note
The submission of this document does not guarantee the issuance of an NPDES permit.
For questions, please contact the DEMLR Regional Office for your area.
DEMLR Regional Office Contact Information:
Asheville Office ......
[phone]
Fayetteville Office
... [phone]
Mooresville Office
... [phone]
Raleigh Office ........
[phone]
Washington Office ... [phone]
Wilmington Office
... [phone]
Winston-Salem ......
[phone]
Central Office .........
[phone]
Page 8 of 8
SWU-NCG14-NOI Last revised 8/01/2017

Raleigh Concrete, LLC
Ready -Mix Concrete Batch Plan
NCG140000 N.O.I.
Narrative of Plant Operation
Waste Sources
The following is a narrative description and identification of each type of process, operation, or production area that
takes place at existing ready -mix concrete batch plant and how those activities might contribute fluid or solid waste.
The plant is in Raleigh, North Carolina at address 1938 South Wilmington Street.
The site consists of a mobile ready -mix batch plant, located towards the rear -center of the property. The mobile
plant is CON -E -CO LO -PRO 327 series and operates as a dry -mix concrete plant. To the south of the plant, in the rear
corner of the property, is a permanent truck wash station and pump house. Fluid and solid wastes are created on
site during typical plant operations. Sources of waste water include vehicle and equipment cleaning, mixing drum
cleaning, and stormwater runoff. Sources of solid waste include excess concrete from trucks returning to the site to
be emptied.
Fluid Waste Management
Mixer trucks enter the site from the driveway access on South Wilmington Street and pull up to the batch plant to
receive automatically weighed materials and water. The trucks then drive to the permanent wash station to be rinsed
before exiting the site. Alternatively, mixer trucks enter the site from the driveway access on South Wilmington
Street and pull to the permanent truck wash station to be rinsed. In both cases, the washing of trucks is producing
waste water. All runoff from this process is collected in the wash station. The wash station contains a series of three
settling tanks. The water is then pumped from the third, and final settling tank, to be recycled for future concrete
mixes on site.
The permanent truck wash station will not discharge any wastewater from the washing of the trucks. This plant is a
relatively small operation, with limited truck washes daily. The only stormwater that is retained by the wash pit is
that which falls in the immediate surrounding area. All other stormwater runoff onsite is directed around the wash
pit. The wash pit is sized to retain necessary wastewater and stormwater that drains to it.
Solid Waste Management
Mixer trucks that arrive on site with any excess or improperly mixed concrete will be emptied and cleaned on site.
All trucks will be emptied and cleaned within the truck wash station to ensure all wastewater is contained in the
wash pit. All excess concrete will be set aside, typically in a mold, to cure and be used as recycled aggregate.
To review, there is no discharge of wastewater from the site. Nor is there any disposal of solid or fluid wastes from
the site. The only wastewater produced onsite is from the washing of mixer trucks. This wastewater enters the wash
station and is processed through a series of settling tanks and later recycled for use on the plant. All stormwater
leaving the site has no contact with the wastewater produced in the operation of the plant. Approved site plan
includes a Stormwater Impact Analysis that further details the impacts the plant has on stormwater and the
surrounding area.

Stormwater Impact Analysis
For
1938 S. Wilmington St
City of Raleigh, North Carolina
Submitted to:
City of Raleigh
Public Works Department
Stormwater Utility
22 West Hargett Street
Raleigh, North Carolina 27601
Prepared for:
Raleigh Concrete, LLC
512 Nowell Road
Raleigh, North Carolina 27607
Prepared by:
PABST DESIGN GROLIP, PA
t N<,INE EKING & CO\S11L I INC,
Date: December 13, 2016
PDG Project No: 238-13
911 Paverstone Drive, Suite E - Raleigh, NC 27615 — Phone [phone] Fax [phone]

Pabst Design Group, PA
911 Paverstone Drive, Ste. E
Raleigh, NC 27615
Table of Contents
I. Introduction
II. Site Location and Description
III. Proposed Improvements
IV. Stormwater Requirements
V. Calculation Methodology
VI. Conclusion
VII. Pre/Post - Development Hydrographs
VIII. TR55 Tc and CN Calculations/Tables
IX. NOAA Precipitation Frequency & Intensity Charts)
X. Erosion Control Calculations
XI. Erosion Control Drainage Area Map
XII. Wake County Soil Survey Map
XIII. USGS Map
XIV. Drainage Area Maps
XV. Nitrogen Loading Calculations
XVI. Nitrogen Loading Maps
XVII. Recorded Plats
Stormwater Impact Analyses
1938 S Wilmington St
Raleigh, North Carolina
PDG: 339-16
v
Section 1
Section 2
Section 3
Section 4
Section 5
Section 6
Section 7
Section 8
Section 9
Section 10
Section 11
Raleigh Concrete, LLC
512 Nowell Raod
Raleigh, NC 27607

Pabst Design Group, PA
911 Paverstone Drive, Ste. E
Raleigh, NC 27615
I. Introduction
Stormwater Impact Analyses
1938 S Wilmington St
Raleigh, North Carolina
PDG: 339-16
Pabst Design Group, PA of Raleigh, NC has been contracted by Raleigh Reclamation, LLC (the
Client) to provide this analysis, along with supporting calculations, to the City of Raleigh (the
COR) for their review. Information contained herewith will assist the COR with their evaluation
of site development for the subject property as it relates to specific COR and State regulations.
II. Site Background
The project site is located in Raleigh, North Carolina on the west side of South Wilmington
Street and consists of one parcel, Wake County Pin 1702-69-1938 (previous two -parcels,
1702-69-1912 and 1703-60-1181). The property, totaling three and eighty-one hundredths
(3.81) acres, is within the Walnut Creek watershed in the Upper Neuse River basin.
The site is currently zoned Heavy Industrial (IH) and is operating under the use category of
Waste Related Service with impervious coverage of one hundred twelve thousand five
hundred twelve (112,512) square feet. While, there is no record of permit for the limits of
gravel on site, the City of Raleigh has accepted the existing gravel/impervious area under the
previously permitted vehicles sales lot impervious area (Transaction Number T-104660).
Therefore, for the purpose of this report, the pre -development conditions will reflect the most
recently permitted site conditions of the commercial vehicles sales lot.
For further differentiation of current site conditions and pre -development site conditions,
please refer to the copy of the recorded plat of the waste related service (BM 2016-1695) and
recorded plat of the vehicle sales lot (BM 1006-1529), included in this report.
III. Pre -Development Site Conditions
The pre -development site conditions consist of a paved asphalt parking lot, commercial
building, accessory buildings, landscaped areas and utility services. As indicated by historic
topography, the pre -development site generally drains in the south east direction to existing
ditch running parallel to the front of the property within the Wilmington Street right-of-way.
Existing impervious coverage is one hundred thirty-nine thousand ninety-two (139,092)
square feet with a percent impervious surface of eighty-three and forty-six hundredths
(83.46). Please refer to the Pre -Development Nitrogen Loading Map and the Pre -Development
Drainage Area Map included in this report for information on pre -development site conditions.
IV. Post -Development Site Conditions
The purpose of this project is to construct a four thousand seven hundred fifty-eight (4,758)
square -foot permanent truck wash out area, three water reclamation tanks, and a pump
house. Infrastructure improvements will include, but are not limited to, the construction of a
private water service to the truck wash area and the approximate location of the mobile
concrete batch plant, which will be assembled on site in the future. The project will disturb
approximately forty-five hundredths (0.45) acres. As indicated by topographic survey, the
subject site will generally drain in the south east direction to existing catch basins running
li Raleigh Concrete, LIC
512 Nowell Raod
Raleigh, NC 27607

Pabst Design Group, PA
911 Paverstone Drive, Ste. E
Raleigh, NC 27615
Stormwater Impact Analyses
1938 S Wilmington St
Raleigh, North Carolina
PDG: 339-16
parallel to the front of the property within the Wilmington Street right-of-way. Post -
development impervious coverage will be one hundred twelve thousand five hundred twelve
(112,512) square feet with a percent impervious surface of sixty seven and seventy-nine
hundredths (67.79).
Please refer to the Post -Development Drainage Area Map included in this report and the
submitted Plot Plan set for more information on the post -development site conditions.
V. Stormwater Requirements
Water Quality
The proposed development is located the Upper Neuse River Basin and is subject to the City
of Raleigh's stormwater regulation. However, the post -development impervious surface, 2.58
acres, is less than the pre -development impervious surface, 3.20 acres. As such, no water
quality treatment will be required. Please refer to the Pre- and Post- Nitrogen Loading Maps
for tabulation of impervious areas.
Water Quantity
Per the City of Raleigh's water quantity requirements, stormwater attenuation is required
onsite in order for the 2-, 10-, and 25 -year, 24-hour storm event peak flows to equal to or
less than pre -development conditions (or within 10% of pre -development levels). However,
after providing analyses, it has been determined that the flow rate for the post -development
condition is less than the pre -developed flow rate for the site. Please refer to the Hydroflow
analysis provided within this report.
VI. Calculation Methodology
Runoff Rates for pre -development and post -development were calculated using the SCS
method. Each drainage area has a time of concentration and runoff curve number calculated
for it. Hydraflow Hydrographs 2007 was utilized for this analysis to overlay hydrographs for
cumulative peak flow analysis, as well as routing flows through the underground detention
system.
The time of concentrations have been calculated using the SCS Segmental Approach (TR -55).
Drainage areas that were less than 5 minutes time of concentration were given an assumed
value of 5 minutes, according to SCS methodology. The segments corresponding to the
calculations for times of concentrations for pre -development and post -development drainage
area maps are included with this report.
Curve number values have been based upon Table 2.2a of the TR -55 Manual. Average
velocities for estimating travel time have been based upon Table 2.1 of the TR -55 Manual.
Values for roughness coefficients were taken from Table 3.1 of the TR -55 Manual. Runoff
Coefficient values for drainage areas have been based upon Table 2.2 of the City of Raleigh
Stormwater Design Manual.
Raleigh Concrete, LLC
512 Nowell Raod
Raleigh, NC 27607

Pabst Design Group, PA
911 Paverstone Drive, Ste. E
Raleigh, NC 27615
Stormwater Impact Analyses
1938 S Wilmington St
Raleigh, North Carolina
PDG: 339-16
Existing soil conditions have been classified as Ma - Made Land for the majority of the site.
The soil group was conservatively assumed to be Group D based upon the description of soil
type provided in the Wake County Soil Survey.
Topographic, location, and boundary survey information was provided by PTS Land Surveying
for the current condition of the site. The City of Raleigh provided historic topography from
2004 for pre -development analysis.
VI1. Conclusion
PDG's analysis consisted of evaluating pre- and post- development conditions of the subject
site. There was a reduction of total nitrogen loads from pre -development conditions to post -
development conditions due to the reduction of impervious surfaces. Additionally, this
reduction of impervious surfaces causes the post -development peak flow rates for all three
design storms to be reduced from pre -development conditions. The pre- vs. post -
development peak flow comparison summary is provided in Table 1. Based upon the analysis
provided within this report, it was determined that neither a treatment device, nor a detention
system is required for this project.
Table 1 Peak Flow Comparison Chart
Table 2 Impervious Area Comparison Chart
Q(2)
Q(10)
Q(25)
Condition
Total Site
Condition
Area
Pavement
(CFS)
(CFS)
(CFS)
Pre -Development
(ACRES)
(ACRES)
(ACRES)
Peak Flows
26.58
39.99
47.84
Post -Development
0.52
0
3.19
Peak Flows
17.58
27.47
33.21
% Change
-33.86%
-31.31%
-30.58%
Table 2 Impervious Area Comparison Chart
iv Raleigh Concrete, LLC
512 Nowell Raod
Raleigh, NC 27607
Building
Asphalt
Gravel
Concrete
Total Site
Condition
Area
Pavement
Pavement
Pavement
Impervious
(ACRES)
(ACRES)
(ACRES)
(ACRES)
(ACRES)
Pre -Development
0.64
2.03
0.52
0
3.19
Post -Development
0.01
0.24
2.19
0.14
2.58
iv Raleigh Concrete, LLC
512 Nowell Raod
Raleigh, NC 27607

Pabst Design Group, PA
911 Paverstone Drive, Ste. E
Raleigh, NC 27615
VIII. Pre / Post - Development Hydrograph
V
Stormwater Impact Analyses
1938 S Wilmington St
Raleigh, North Carolina
PDG: 339-16
Raleigh Concrete, LLC
512 Nowell Raod
Raleigh, NC 27607

Hydrograph Return Period RecP
Hy ra Pow Hydrographs Extension for AutoCAD®Civil 3D® 2014 by Autodesk, Inc. v10.3

Hydrograph Summary Report
Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2014 by Autodesk, Inc. v10.3
Hyd.
No.
Hydrograph
type
(origin)
Peak
flow
(cfs)
Time
interval
(min)
Time to
Peak
(min)
Hyd.
volume
(cuft)
Inflow
hyd(s)
Maximum
elevation
(ft)
Total
strge used
(cuft)
Hydrograph
Description
1
SCS Runoff
26.58
2
716
57,810
------
Pre-Dev Drainage Area
2
SCS Runoff
17.68
2
716
37,169
—
--
Post-Dev Drainage Area
SIA_12-13-16_SAB.gpw
Return Period: 2 Year
Wednesday, 12 / 14 / 2016

3
Hydrograph Report
Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2014 by Autodesk, Inc. v10.3
Wednesday, 12 / 14 / 2016
yd. No. 1
Pre-Dev Drainage Area
Hydrograph type
= SCS Runoff
Peak discharge
= 26.58 cfs
Storm frequency
= 2 yrs
Time to peak
= 716 min
Time interval
= 2 min
Hyd. volume
= 57,810 cuft
Drainage area
= 6.160 ac
Curve number
= 94*
Basin Slope
= 0.0%
Hydraulic length
= 0 ft
Tc method
= User
Time of conc. (Tc)
= 5.00 min
Total precip.
= 3.42 in
Distribution
= Type II
Storm duration
= 24 hrs
Shape factor
= 484
* Composite (Area/CN) = [(3.630 x 98) + (2.010 x 89) + (0.520 x 91)] / 6.160
Q (cfs
28.00
20.00
16.00
12.00
M
4.00
Pre-Dev Drainage Area
Hyd. No. 1 -- 2 Year
Q (cfs)
28.00
24.00
20.00
16.00
12.00
M
4.00
0.00 0.00
0 120 240 360 480 600 720 840 960 1080 1200
Hyd No. 1 Time (min)

3
Hydrograph Report
Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2014 by Autodesk, Inc. v10.3
Wednesday, 12 / 14 / 2016
Hyd. No. 2
Post-Dev Drainage Area
Hydrograph type
= SCS Runoff
Peak discharge
= 17.68 cfs
Storm frequency
= 2 yrs
Time to peak
= 716 min
Time interval
= 2 min
Hyd. volume
= 37,169 cuft
Drainage area
= 4.430 ac
Curve number
= 91*
Basin Slope
= 0.0%
Hydraulic length
= 0 ft
Tc method
= User
Time of conc. (Tc)
= 5.00 min
Total precip.
= 3.42 in
Distribution
= Type II
Storm duration
= 24 hrs
Shape factor
= 484
* Composite (Area/CN) = [(1.960 x 89) + (0.380 x 98) + (2.090 x 91)] / 4.430
Q (cfs
18.00
15.00
12.00
MM
RM
OM
Post-Dev Drainage Area
Hyd. No. 2 -- 2 Year
Q (cfs)
18.00
15.06
12.00
• IR
3.00
0.00 0.00
0 120 240 360 480 600 720 840 960 1080 1200 1320
Hyd No. 2 Time (min)

4
Hydrograph Summary Report
Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2014 by Autodesk, Inc. v10.3
Hyd.
Hydrograph
type
(origin)
Peak
flow
(cfs)
Time
interval
(min)
Time to
Peak
(min)
Hyd.
volume
(cuft)
Inflow
hyd(s)
Maximum
elevation
(ft)
Total
strge used
(cult)
Hydrograph
Description
1
SCS Runoff
39.99
2
716
89,482
—
Pre-Dev Drainage Area
2
SCS Runoff
27.47
2
716
59,448
—
Post-Dev Drainage Area
SIA 12-13-16_SAB.gpw
Return Period: 10 Year
Wednesday, 12 / 14 / 2016

0.00 ' 1- 0.00
0 120 240 360 480 600 720 840 960 1080 1200
Hyd No. 1 Time (min)
5
Hydrograph
Report
Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2014 by Autodesk, Inc. v10.3
Wednesday, 12 / 14 / 2016
Hyd. No. 1
Pre-Dev Drainage Area
Hydrograph type
= SCS Runoff Peak discharge
= 39.99 cfs
Storm frequency
= 10 yrs
Time to peak
= 716 min
Time interval
= 2 min
Hyd. volume
= 89,482 cuft
Drainage area
= 6.160 ac
Curve number
= 94*
Basin Slope
= 0.0%
Hydraulic length
= 0 ft
Tc method
= User
Time of conc. (Tc)
= 5.00 min
Total precip.
= 4.96 in
Distribution
= Type II
Storm duration
= 24 hrs
Shape factor
= 484
* Composite (Area/CN) = [(3.630 x 98) + (2.010 x 89) + (0.520 x 91)) / 6.160
Pre-Dev Drainage Area
Q (cfs)
Hyd. No. 1 -- 10 Year
Q (cfs)
40.00
11 1
1 1 40.00
0.00 ' 1- 0.00
0 120 240 360 480 600 720 840 960 1080 1200
Hyd No. 1 Time (min)

5
Hydrograph Report
Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2014 by Autodesk, Inc. 00.3
Wednesday, 12 / 14 / 2016
- lyd. No. 2
Post-Dev Drainage Area
Hydrograph type
= SCS Runoff
Peak discharge
= 27.47 cfs
Storm frequency
= 10 yrs
Time to peak
= 716 min
Time interval
= 2 min
Hyd. volume
= 59,448 cuft
Drainage area
= 4.430 ac
Curve number
= 91*
Basin Slope
= 0.0%
Hydraulic length
= 0 ft
Tc method
= User
Time of conc. (Tc)
= 5.00 min
Total precip.
= 4.96 in
Distribution
= Type II
Storm duration
= 24 hrs
Shape factor
= 484
Composite (Area/CN) = [(1.960 x 89) + (0.380 x 98) + (2.090 x 91)j / 4.430
Post-Dev Drainage Area
Q (cfs) Hyd. No. 2 -- 10 Year Q (cfs)
28.00 28.00
.00 24.00
20.00 20.00
16.00 16.00
12.00 12.00
8.00 8.00
4.00 4.00
0.00 0.00
0 120 240 360 480 600 720 840 960 1080 1200
Hyd No. 2 Time (min)

Hydrograph Summary Report
Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2014 by Autodesk, Inc. 00.3
Hyd.
No.
Hydrograph
type
(origin)
Peak
flow
(cfs)
Time
Interval
(min)
Time to
Peak
(min)
Hyd.
volume
(cuft)
Inflow
hyd(s)
Maximum
elevation
(ft)
Total
strge used
(cult)
Hydrograph
Description
1
SCS Runoff
47.84
2
716
108,336
---
Pre-Dev Drainage Area
2
SCS Runoff
33.21
2
716
72,817
Post-Dev Drainage Area
SIA 12-13-16_SAB.gpw
Return Period: 25 Year
Wednesday, 12 / 14 / 2016

7
Hydrograph
Report
Hydraflow Hydrographs Extension for AutoCADD Civil 3D® 2014 by Autodesk, Inc. 00.3
Wednesday, 12 / 14
/ 2016
- lyd. No. 1
Pre-Dev Drainage Area
Hydrograph type
= SCS Runoff Peak discharge
= 47.84 cfs
Storm frequency
= 25 yrs
Time to peak
= 716 min
Time interval
= 2 min
Hyd. volume
= 108,336 cuft
Drainage area
= 6.160 ac
Curve number
= 94*
Basin Slope
= 0.0%
Hydraulic length
= 0 ft
Tc method
= User
Time of conc. (Tc)
= 5.00 min
Total precip.
= 5.87 in
Distribution
= Type II
Storm duration
= 24 hrs
Shape factor
= 484
* Composite (Area/CN) _ [(3.630 x 98) + (2.010 x 89) + (0.520
x 91)] / 6.160
Pre-Dev Drainage Area
Q (cfs)
Hyd. No. 1 -- 25 Year
Q (cfs)
50.00
50.00
40.00
40.00
30.00
30.00
20.00
20.00
10.00
10.00
0.00
0.00
0 120
240 360
480 600 720 840 960 1080 1200
Hyd No. 1
Time
(min)

11 ������1� 1 /
111 �=wlI7
1 1 � M
1 1 1 ������M � 1 1/
0.00 1 0.00
0 120 240 360 480 600 720 840 960 1080 1200
Hyd No. 2 Time (min)
7
Hydrograph
Report
Hydraflow Hydrographs Extension for AutoCAD® Civil 3D@2014 by Autodesk, Inc. v10.3
Wednesday, 12 / 14 / 2016
Hyd. No. 2
Post-Dev Drainage
Area
Hydrograph type
= SCS Runoff
Peak discharge
= 33.21 cfs
Storm frequency
= 25 yrs
Time to peak
= 716 min
Time interval
= 2 min
Hyd. volume
= 72,817 cuft
Drainage area
= 4.430 ac
Curve number
= 91*
Basin Slope
= 0.0%
Hydraulic length
= 0 ft
Tc method
= User
Time of conc. (Tc)
= 5.00 min
Total precip.
= 5.87 in
Distribution
= Type II
Storm duration
= 24 hrs
Shape factor
= 484
Composite (Area/CN) = [(1.960 x 89) + (0.380 x 98) + (2.090 x 91)] / 4.430
Post-Dev Drainage Area
Q (cfs)
Hyd. No. 2 -- 25 Year
Q (cfs)
35.00
1 1 1
1 1 35.00
11 ������1� 1 /
111 �=wlI7
1 1 � M
1 1 1 ������M � 1 1/
0.00 1 0.00
0 120 240 360 480 600 720 840 960 1080 1200
Hyd No. 2 Time (min)

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Pabst Design Group, PA
911 Paverstone Drive, Ste. E
Raleigh, NC 27615
IX. TR55 Tc & CN Calculations
VI
Stormwater Impact Analyses
1938 S Wilmington St
Raleigh, North Carolina
PDG: 339-16
Raleigh Concrete, LLC
512 Nowell Raod
Raleigh, NC 27607

Time of Concentration Calculatior
SCS Segmental Method
Project: 1938 S. Wilmington St.
Purpose: Determine tc for PRE -development DA -1
Prepared by SAB Date: 13 -Dec -16
Checked by: PDP Date: 13 -Dec -16
Sheet Flow Segment ID
AB
1. Surface description (TR -55, Table 3-1)
asphalt, smoot
2. Manning's roughness coeff., n (TR -55, Table 3-1)
0.011
3. Flow length, L (Total < 100 ft) * ft
°'e
214
4. Two-year 24-hour rainfall, P (NOAA data) T, = 0.0 0 7 (n L) in
3.49
z°sS°., fttJ
5. Land slope, S P,03 SOA
0.045
6. Travel time, t hr
0.03
Sheet Flow Segment ID BC
1. Surface description (TR -55, Table 3-1) asphalt, smoot
2. Manning's roughness coeff., n (TR -55, Table 3-1) 0.011
3. Flow length, L (Total < 100 ft)' ft 44
4. Two-year 24-hour rainfall, P (NOAH data) T, = 0.0 0 7 n L) °'e in 3.49
5. Land slope, S P20 5 SO.4 ft/ 0.068
6. Travel time, t hr 0.01
Sheet Flow Segment ID CD
1. Surface description (TR -55, Table 3-1) asphalt, smoot
2. Manning's roughness coeff., n (TR -55, Table 3-1) 0.011
3. Flow length, L (Total < 100 ft)' ft 29
4. Two-year 24-hour rainfall, P (NOAH data) T, = 0.0 0 7 (n L)" e in 3.49
5. Land slope, S p °.550.4 ft/1 0.100
6. Travel time, t hr 0.00
Sheet Flow Segment ID DE
1. Surface description (TR -55, Table 3-1) asphalt, sr
2. Manning's roughness coeff., n (TR -55, Table 3-1) 0.011
3. Flow length, L (Total < 100 ft)' ft 92
4. Two-year 24-hour rainfall, P (NOAA data) T, = 0.00 7 (nL )°'B in 3.49
5. Land slope, S p z ° .s s °.4 ft/q 0.020
6. Travel time, t hrl 0.02
Sheet Flow Segment ID EF
1. Surface description (TR -55, Table 3-1) asphalt, smoot
2. Manning's roughness coeff., n (TR -55, Table 3-1) 0.011
3. Flow length, L (Total < 100 ft)' ft 151
4. Two-year 24-hour rainfall, P (NOAA data) 7� = 0.007 (nL )°'8 in 3.49
5. Land slope, S pZ° .S S 0.4 ft/ 0.020
6. Travel time, t hr 0.03
TIME OF CONCENTRATION, Tc h4 0.08
min 4.8

Runoff Curve Number (CN) Calculation
SCS Segmental Method
Project:
1938 S. Wilmington St.
Condition:
Pre -development
Purpose:
Determine CN Values for Drainage Areas
Prepared by
SAB Date: 13 -Dec -16
Checked by:
PDP Date: 13 -Dec -16
Total Site Area:
3.81 Acres
Total Drainage Area:
6.16 Acres
Drainage Area:
DA -1
* Open Space, Fair - was recently graded and seeded during constrction of Bartram Place
Composite CN = Total (CN*A) / Total A Totals 5.64 534.63
Composite CN 1 94.8 (for prev-development flow from DA -1)
Soil Group
Cover Type
CN Value
Area (ac)
CN*A (ac)
Open, poor
Sub Area 1
D
condition
89
2.01
178.89
Impervious,paved
Sub Area 2
D
98
3.63
355.74
Impervious,gravel
Sub Area 3
D
91
0.52
47.32
* Open Space, Fair - was recently graded and seeded during constrction of Bartram Place
Composite CN = Total (CN*A) / Total A Totals 5.64 534.63
Composite CN 1 94.8 (for prev-development flow from DA -1)

Time of Concentration Calculation
SCS Segmental Method
Project: 1938 S. Wilmington St.
Purpose: Determine tc for POST -development DA -1
Prepared by SAB Date: 13 -Dec -16
Checked by: PDP Date: 13 -Dec -16
Sheet Flow
1. Surface description (TR -55, Table 3-1)
2. Manning's roughness coeff., n (TR -55, Table 3-1)
3. Flow length, L (Total < 100 ft) *
4. Two-year 24-hour rainfall, P (NOAA data) T, = 0.0 07 (nL )°'8
5. Land slope, S P 0.ss 0.4
z
6. Travel time, T t
Sheet Flow
1. Surface description (TR -55, Table 3-1)
2. Manning's roughness coeff., n (TR -55, Table 3-1)
3. Flow length, L (Total < 100 ft) *
4. Two-year 24-hour rainfall, P (NOAA data) T, = 0.0 07 (nL )°'S
5. Land slope, S P °.s 0.4
6. Travel time, T t
Sheet Flow
1. Surface description (TR -55, Table 3-1)
2. Manning's roughness coeff., n (TR -55, Table 3-1)
3. Flow length, L (Total < 100 ft) *
4. Two-year 24-hour rainfall, P (NOAA data) T, = 0.0 07 (n L )0'8
5. Land slope, S Pz °.SS 0.4
6. Travel time, T t
TIME OF CONCENTRATION, Tc
for DA -1, Pre -development
Segment ID
ft
in
ft/ft
hr
Segment ID
ft
in
ft/ft
hr
Segment ID
ft
in
ft/ft
hr
AB
grass, short
0.150
83
3.49
0.120
0.07
BC
gravel, smooth
0.011
78
3.49
0.120
0.01
CD
concrete, smooth
0.011
42
3.49
0.050
0.01
hri 0.072
min 4.3

Runoff Curve Number (CN) Calculation
SCS Segmental Method
Project:
1938 S. Wilmington St.
Condition:
Pre -development
Purpose:
Determine CN Values for Drainage Areas
Prepared by
SAB Date: 13 -Dec -16
Checked by:
PDP Date: 13 -Dec -16
Total Site Area:
3.81 Acres
Total Drainage Area:
4.43 Acres
Drainage Area:
DA -1
* Open Space, Fair - was recently graded and seeded during constrction of Bartram Place
Composite CN = Total (CN*A) / Total A Totals 2.34 211.68
Composite CN 1 90.5 (for prev-development flow from DA -1)
Soil Group
Cover Type
CN Value
Area (ac)
CN*A (ac)
Open, poor
Sub Area 1
D
condition
89
1.96
174.44
Impervious,paved
Sub Area 2
D
98
0.38
37.24
Impervious,gravel
Sub Area 3
D
91
2.09
190.19
* Open Space, Fair - was recently graded and seeded during constrction of Bartram Place
Composite CN = Total (CN*A) / Total A Totals 2.34 211.68
Composite CN 1 90.5 (for prev-development flow from DA -1)

Chapter 2 Estimating Runoff - Technical Release 55
Urban Hydrology for Small Watersheds
Table 2-2a Runoff curve numbers for urban areas 1/
Curve numbers for
Cover description hydrologic soil group
Average percent
Cover type and hydrologic condition impervious area V A
Fully developed urban areas (vegetation established)
Open space (lawns, parr, golf courses, cemeteries, etc.) 3':
Poor condition (grass cover < 50%) ..........................................
Fair condition (grass cover 50% to 75%) .................................
Good condition (grass cover > 7596) .........................................
Impervious areas:
Paved parking lots, roofs, driveways, etc.
(excluding right-of-way) .............................................................
Streets and roads:
Paved; curbs and storm sewers (excluding
right-of-way).............................................................................
Paved, open ditches (including right -of --way) .........................
Gravel (including right -of -way) .................................................
Dirt (including right -of -way) ......................................................
Western desert urban areas:
Natural desert landscaping (pervious areas only) 9/ .....................
Artificial desert landscaping (impervious weed barrier,,
desert shrub with 1- to 2 -inch sand or gravel mulch
and basin borders)......................................................................
Urban districts:
Commercialand business.................................................................
Industrial.................. ..........................................................................
Residential districts by average lot size: _ .
1/8 acre or less (town houses)..........................................................
U4acre ................................................................................................
1/3 acre..............................................................................................
112 acre................................................................................................
1 acre...............................................................................................
2 acres..................................................................................................
Developing urian areas
Newly graded areas
(pervious areas only, no vegetation) Y ...... ....................... --..............................
Idle lands (CN's are determined ugrng cover types
_similar to those in table 2-2c).
68
49
39
0
79
69
61
C D
86
79 84
74 80
77 86 91 94
I Average runoff condition, .and Ie = 0.2S.
8 The average percent impervious area shown was used to develop the composite CN's Other assumptions are as follows: impervious areas are
directly connected to the drainage system, impervious areas have a CN of 98, and pervious areas are considered equivalent to open space in
good hydrologic condition. CN's for other combinations of conditions may be computed using figure 23 or 2-4:
8 CNS shown are equivalent to those of pasture. Composite CN's may be computed for other combinations of open space
cover type.
4 Composite CN's for natural desert landscaping should be computed using figures 23 or 24 based on the impervious area percentage
(CN = 98) and the pervious area CN. The pervious area CN's are assuned equivalent to desert shrub in poor hydrologic condition.
6 Composite CN's to use for the design of temporary measures during grading and construction should be computed using figure 2.3 or 2-1
based on the degree of development (impervious area percentage) and the CN's for the newly graded pervious areas
(210 -VI -TR -65, Second Ed., June 196) 2-5
98
98
98
98
98
98
98
83
76
89
85
92
93
72
82
87
89
63
77
85
88
96
96
96
96
85
89.
92
94
95
72
81.
88
91
93
65
77
85
90
92
38
61
75
83
87
30
57
72
81
86
25
54
70
80
85
20
51
68
79
84
12
46
65
77
821,
77 86 91 94
I Average runoff condition, .and Ie = 0.2S.
8 The average percent impervious area shown was used to develop the composite CN's Other assumptions are as follows: impervious areas are
directly connected to the drainage system, impervious areas have a CN of 98, and pervious areas are considered equivalent to open space in
good hydrologic condition. CN's for other combinations of conditions may be computed using figure 23 or 2-4:
8 CNS shown are equivalent to those of pasture. Composite CN's may be computed for other combinations of open space
cover type.
4 Composite CN's for natural desert landscaping should be computed using figures 23 or 24 based on the impervious area percentage
(CN = 98) and the pervious area CN. The pervious area CN's are assuned equivalent to desert shrub in poor hydrologic condition.
6 Composite CN's to use for the design of temporary measures during grading and construction should be computed using figure 2.3 or 2-1
based on the degree of development (impervious area percentage) and the CN's for the newly graded pervious areas
(210 -VI -TR -65, Second Ed., June 196) 2-5

Chapter 3 Time of Concentration and Travel Time Technical Release 55
Urban hydrology for Small Watersheds
Figure 3-1 Average velocities for estimating travel time for shallow concentrated flow
.50
.20
.10
S.
0
a .06
04
3
.02
.01
.005
1
3-2
2 4 6 10 20
Average velocity (ft/sec)
(210-VI--TR-6, Second Ed., June 1986)

Chapter 3
Sheet flow
Time of Concentration and Travel Time Technical Release 65
Urban Hydrology for Small Watersheds
Sheet flow is flow over plane surfaces. It usually
occurs in the headwater of streams. With sheet flow,
the friction value (Manning's n) is an effective rough-
ness coefficient that includes the effect of raindrop
impact; drag over the plane surface; obstacles such as
litter, crop ridges, and rocks; and erosion and trans-
portation of sediment. These n values are for very
shallow flow depths of about 0.1 foot or so. Table 3-1
gives Manning's n values for sheet flow for various
surface conditions.
Table 3-1 Roughness coefficients (Manning's n) for
��■ sheet flow
Surface description n y
Smooth surfaces (concrete, asphalt,
gravel, or bare soil) ..........................................
CED
Fallow (no residue) ..................................................
0.06
Cultivated soils:-
oils:Residue
Residuecover _20% ..................................... :...
0.06
Residue cover >20°Yo.........................................
0.17
Grass:
Short grass prairie ............................................
O.lb
Dense grasses V ................................................
0.24
Betmudagrass..................................................
0.41
Range (natural).........................................................
0.13
Woods:&
Ughtunderbrush ..............................................
0.40
Dense underbrush ............................................
0.80 .
I The n values are a composite of information compiled by Engrnan
(1986).
2 Includes species such as weeping lovegrass, bluegrass, buffalo
grass, blue grama grass, and native grass mixtures -
3 When selecting n, consider cover to a height of about 0.1 ft. This
is the only part of the plant cover that will obstruct sheet flow.
For sheet flow of less than 300 feet, use Manning's
kinematic solution (Overtop and Meadows 1976) to
compute Tt:
Tt —
_ 0.007(nL)o.s
(p2
)0.ss0.4 ��
where:
Tt = travel time (hr),
n = Mannings roughness coefficient (table 3-1)
L = flow length (ft)
PZ = 2 year, 24-hour rainfall (in)
s = slope of hydraulic grade line
(Land slope, ft/ft)
This simplified form of the Mannft 's kinematic solu-
tion is based on the following: (1) shallow steady
uniform flow, (2) constant intensity of rainfall excess
(that part of a rain available for runoff), (3) rainfall
duration of 24 hours, and (4) minor effect of infiltrar
tion on travel time. Rainfall depth can be obtained
from appendix B.
Shallow concentrated flow
After a maximum of 300 feet, sheet flow usually be-
comes shallow concentrated flow. The average veloc-
ity for this flow can be determined from figure 3-1, in
which average velocity is a function of watercourse
slope and type of channel. For slopes less than 0.005
ft/ft, use equations given in appendix F for figure 3-1.
Tillage can affect the direction of shallow concen-
trated flow. Flow may not always be directly down the
watershed slope if tillage rums across the slope.
After determining average velocity in figure 3-1, use
equation 3-1 to estimate travel time for the shallow
concentrated flow segment.
Open channels
Open channels are assumed to begin where surveyed
cross section information has been obtained, where
chanliels are visible on aerial photographs, or where
blue lines (indicating streams) appear on United States
Geological Survey (USGS) quadrangle sheets.
Manning's equation or water surface profile informa-
tion can be used to estimate average flow velocity.
Average flow velocity is usually determined for bank-
full
ankfull elevation.
(210 -VI -TR -b, Second Ed., June 1486)
M

10
SOIL $UR` GY
C-65 to 72 lnche, -I-, mottled gray, yellowish -brown, and red
clary; nla.tsive; firm when molst; strongly acid.
The A horizons range from 8 to 20 inches 1n combined thiclt-
neas and from dark brown or dark grayish brown to light
yellnwish brown or light gr ty in color, The Bt horizons range
from 21 to tam Web" in combined thicluiesca. Their texture is
mostly sandy loam or .ands clay login that is 18 to 35 percent
clity. In places these horizons contain po ekets and lenses of
sand. The color of the Bt horizons ranges from yellowish
brown to pale yellow or light brownish gray in 1oYR or more
yell:ow!sh hues. lit places few to common gray mattley are
within 10 inches of the top of the uppermost Bt horizon. The
133g horizon I% pale brown to light brownish gray or brownicth
yellow and generally contains db;tinct, grayish mottles. The
combined thicknews of the A horizons and 13 horizon% is more
than 60 inches, Depth to bedrock is ntnre than 20 feet
Lynchburg Polls occur with Goldsboro and Rain% soils, and
their texture is ,similar to the texture of those soils. They are
less well drained tham the Goldsboro tsoils, however, and are
better drained than the Rains.
Lynchburg sandy loam (0 to 2 pervent, slopes) (Ly).—
This is the only L,ynehburg soil mapped in Wake Coun-
tyy Tt is iii depressions in uplajids of the Coastal Plaits.
The surface layer is dark -brown or light -gray to very
dark gray sanely loam 8 to 20 inches thick.'I'he sitbsoil is
30 to 60 inches thick and is pale -yellow to yellowish -
brown, friable sandy loam to sandy clay loalll mottled
with shades of gray.
Infiltration: is good, and surface runoff is slow. 'i'his
soil is easy to keep in good tilt.h and can be worked
throughout a wide range of moisture content.
Drainage is required for most row crops to do taell on
this soil. Tl proper drainage is provided, this soil is well
suited to most of the locally grown crops. It. is used
llla.iltly for row crops ot• pastulT. (Capability unit IIs -1,
woodfand suitability group 1, wildlife suitability grotil,)
Made land (Ma) is a miscellaneous land type in which
Hie areas hate been altered by nlan to the extent that the
profile of the original soils cannot be recognized. '1.'lle
altered soil mat.el sal docs not function as clad the original
soil, and In alliin`' places It does not re; etrlble the original
soil.
Some areas of -Made land wero ;hauls wlie.n cnttinn and
filling was ([one io construct parking lots, ail•flelds, indus-
trial sites, and highway inte!•chringes. In inai y places all
or past. of the eolith and part of the lnateri.il uwlPrlyinn
the original soils was cart from one area, and teas niove.d
to another spot for lice as firl rna.terial. Other areas of
Afadp l:tnd iia•e steal• gltarnes Wltel•P the overl,ur•a(era hays
been (stamped into large rnollnds. In fllose, plaices gravel
has been sprerLd and packed into the soils until the soil
material is compacted and hard.
The areas included in this land tgpe are so diverse
in characteristics t.1 tt general statements cannot be made
about thein. Onsite esanrillation of %sisal al•ea is IIPCPS4a1•b'
before any land nse is planned. (Not placed in it capa-
bility unit; woodland suitability 91.0111) 13, wildlife suit.-
ability gr011p a�
Madison Series
The Madison series coll,sists of gently sloping to mod
erateiy steep, sleep, well -drained soils that occupy fairly
small areas on Piedmont uplands in the northern part
of the county. These soils are on side slopes and
rounded divides where tile difference in elevation Is ab0
60 feet between the highest- and the lowest points. They
lisave formed under forest: in material that weathered
from mica schist, inicat guei,,s, and otlier acidic rocks.
Natural fertility and the content of organic matter are
low, Permeability is moderate, and the -available Nrater
capacity is nieditttn. The shrink -shell potential is mod-
erate. Exr..ept, in areas that lt:t.ae received lilac, these soil3
are strongly acid. Response is good if suitable nppliea-
tiot-is of lime and fertilizer are inade.
The liladison soils of Wake County are not important
for fanning. They are Ino tly in forest.
Ri,presentative profile of a Madison sanely loam in a
,wooded area. 1:>,i miles west of the Nouse. lliver Bridge.
on N.C. Highway No. 98 and 10 yards south of road:
Ap-0 to C inches, brown (16YR 5/3) sandy tonna; weak,
medium, granular structure; very friable when 1noW.;
many fine, woody and fibrous roots; common fine mica
flakes; fete small quartz anti quartz mica %(-hit peb-
bles; medium acid; nbrnpt, navy boimdary.
B1-6 to 12 inches, red (2.5YR 4/6) heavy Bundy clay Irma;
weak, nteflinm. snuingular blocky structure; friable
when moist, slightly sticky and slightly plastic avhwt
r-ct ; common, fine, Fvoody and fibrous roots; common
fine mica flake;4: strongly acid; abrupt, wavy bound-
ary-
R2't--1° to ?t) inches, reel (2.5YR 4/6) clay lows: moderate,
medium, snbankular blocky structure; friable trIlcm
moist, "lightly Sticky and slightly silastic when wet ;
this clay films ; c•om.mon. fine, woody ail Rbrous
roors; innny fine mica flakes; feu' partly di�int(-
grated schist frngntents; strongly field; abrupt, xv)Y
boundary.
Mt --26 to 32 inches, red (2.:Wrl 4%6) sandy clay loam ; anad
ale, medium, subangnlar blrxky structure: friable
tvheu hoist, slightly sticky and slightly plastic when
%-L: few tithi ela v films: fo w, siltall, woolly roots;
tunny fine mica flake, ; coiniamn schist fraagnients, and
pais 3,01mv :and dusky -red wortles around the frag,-
¢uvrat0; strongly acid: clenr, wavy bound!try.
C—:3:3 to tS ino•hc , 4, mottled dusky red. red, pale -yellow,
strong-hrmyn. and brown silt lonin disintegrated
cluartz mica schist: cinnnion dark t1okes that appear
to i t- di :hLtP,grntPd gamier; few, small, %voo dy roots
cYtwiding to a depth of more than -IS inehei ; strongly
acid.
The Alt horizon ratriges froin 3 to 10 inches in thic-kiw.Ss aacl
front dart: brown to hrowa; in color, The Ii horirony range:
from 111 to 8-15 inches in c•onibined thickness nud front sandy
e•lny- lunnt to clay in texture. The ail horizon is+ yellowish red
to red. Tho, aa:odal color of the B1' L• orizons is red of 2.5YRtitle, but the color of those horizons range, to dark red. The
ttarntaer of mica Unlies ranges from few to colanton hi tllcr A
burizou and from common to ninny in the ail horizon, haat the
Wt. horizon, and, in places, the C horizon, corntaain ninny taie,a
fialcea. The combined thickness of the Ap horizon and D hori-
zons, range, from 20 to 40 luncws• and, in plaoos, the:
thickness varies grParly within a short lateral distance. Melitis
to bard rock ranges Froin 5 to mare Minn t:5 feet.
3ladison soils occur with the Cecil, (leorgeville, and Lloyd
snails. bait they have a thinner sohaua an(i contaill xuore mica
flakes thant tlai)se soils. The Madison Soils contain less silt than
the Georgeville soil, unil nr,� nwre acid than the Lloyd soile.
Madison sandy loam, 2 to 6 percent slopes, eroded
(Md132).---2I'lai soil i:-; on smooth intc•rstrelttn clia•icle=:. Its
surface layer ik to 10 i!�Ches thiel(. In .nand• places it i
11, lilixtilre of the renwining original surface soil arid of
rimterial from Hip subl oil. Iii the les-, croded itreil.s, t
Surface layer is 'Iarli llrowil to !)rowlt, blit the valvar

2.2.2 Runoff Coefficient The runoff coefficient (C) is the variable of the rational method least
susceptible to precise determination and requires judgment and -
understanding on the part of the design engineer. While engineering
judgment will always be required in the selection of runoff coefficients,
typical coefficients represent the integrated effects of many drainage
basin parameters. Table 2.2 gives the recommended runoff coefficients
for the rational method.
Table 2.2 Recommended Runoff Coefficient Values
(Sources: North Carolina Erosion and Sediment Control Planning and Design
Manual and The City of Raleigh's Storm Drainage Design Manual, 1989)
Description of Area
Runoff Coefficient C
Woodlands
0.20-.025
Parks, cemeteries
0.25
Playgrounds
0.35
Lawns:
Sandy soil, flat, 2%
0.10
Sandy soil, average, 2 - 7%
0.15
Sandy soil, steep, > 7%
0.20
Clay soil, flat, 2%
0.17
Clay soil, average, 2 - 7%
0.22
Clay soil, steep, > 7%
0.35
Graded or no plant cover:
Sandy soil, flat, 0 - 5%
0.30
Sandy soil, flat, 5 - 10%
0.40
Clayey soil, flat, 0 - 5%
0.50
Clayey soil, average, 5 - 10%
0.60
Residential:
Single-family (R - 4)
0.50
Single-family (R - 6)
0.55
Multi -family (R - 10)
0.60
Multi -family (R - 20)
0.70
Multi -family (R - 30)
0.75
Business:
O & 1 (1, 11, III)
0.85
11 &12
0.85-0.95
Shopping Centers
0.85-0.95
Streets:
Gravel areas
0.50
Drives, walks, and roofs
0.95
Asphalt and Concrete
0.95 1.00
City of Raleigh January 2002
Stormwater Design Manual Page 39

Pabst Design Group, PA Stormwater Impact Analyses
911 Paverstone Drive, Ste. E 1938 S Wilmington St
Raleigh, NC 27615 Raleigh, North Carolina
PDG: 339-16
X. NOAA Precipitation Frequency & Intensity Charts)
Vii Raleigh Concrete, LLC
512 Nowell Raod
Raleigh, NC 27607

NOAA Atlas 14, Volume 2, Version 3
Location name: Raleigh, North Carolina, USA*
Latitude: 35.7549*, Longitude: -78.64220
41",
Elevation: 239.7 ft**
'source: ESRI MaPs�..
"source: USGS
POINT PRECIPITATION FREQUENCY ESTIMATES
G.M. Bonnin, D. Martin, B. Lin, T. Parzybok, M.Yekta, and D. Riley
NOAA, National Weather Service, Silver Spring, Maryland
PF tabular I PF graphical I Maps & aerials
PF tabular
PDS -based point precipitation frequency estimates with 90% confidence intervals (in inches/hour)1
Average recurrence interval (years)
Duration �������
1 2 5 10 25 50 100 200 500 1000
5{nin 4.90 F 5.717 F--6.-56--]F-7-.3-0--]F--8-.06-7 F 8.64 F 9.16 9.59 10.1 10.5
(4.48-5.34) 1 (5.24-6.24) 1 (6.02-7.16) 1 (6.68-7.97) (7.36-8.80) (7.84-9.41) (8.26-9.96) 1 (8.60-10.5) 1 (8.98-11.0) 11 (9.26-11.5)
10�t1in 3.91 4.57 526 ) ( 5.84 6.43 6.88 ) 7.27 ) 7.60 7.98 ) 827
(3.58-4.27) (4.19-4.99) (4.82-5.74 5.35-6.37) (5.86-7.01) (6.25-7.49 (6.56-7.92 (6.82-8.29) (7.10-8.70 (7.29-9.03)
15{tlin 326 3.83 4A3 4.92 5-A 3- 5.81 6.13 6.40 6.70 6.92
(2.98-3.56) 1 (3.51-4.18) 1 (4.07-4.84) 1 (4.51-5.37) 1 (4.95-5.92) 1 (5.27-6.32) (5.52-6.67) (5.74-6.98) (5.96-7.30) 1 (6.10-7.56)
30 -min 223 2.64 F 3.15 7 F --35-7-17-4.0 2 4.37 4.69 4.98 5.33 5.60
(2.04-2.44) 1 (2.42-2.89) 1 (2.89-3.44) 1 (3.27-3.89) 1 (3.67-4.38) 1 (3.97-4.76) (4.23-5.11) (4.47-5.43) (4.74-5.81) 1 (4.94-6.12)
60 -min 1.39 1.66 2.02 2.32 2.68 2.96 3.23 3.49 3.82 4.09
(1.27-1.52) 1 (1.52-1.81) 1 (1.85-2.20) 1 (2.13-2.53) 1 (2.44-2.92) 1 (2.69-3.23) (2.91-3.52) 1 (3.13-3.81) (3.40-4.17) (3.61-4.47)
2 -hr 0.815 0.975 1.20 1.39 1.63 1.82 2.01 220 2.45 2.65
1(0.742-0.897)1(0.890-1.07) 1 (1.09-1.32) 1 (1.26-1.53) 1 (1.47-1.78) 1 (1.64-2.00) (1.79-2.20) 11 (1.95-2.41) (2.15-2.68) (2.31-2.91)
3 -hr 0.574 0.688 0.850 0.994 1.18 1.33 1 A8 1.64 1.85 2.03
1(0.524-0.633)1(0.629-0.758)1(0.775-0.936)1(0.903-1.09) 1 (1.06-1.29) 1 (1.19-1.46) 1 (1.32-1.62) 11 (1.45.1.79) 1 (1.62-2.02) 11 (1.76-2.23)
6 -hr 0.346 0.414 0.512 0.599 0.711 0.807 0.904 1.00 1.14 1.26
(0.317-0.379) (0.380-0.455) (0.468-0.561) (0.546-0.656) (0.644-0.777) (0.727-0.880) (0.806-0.984) (0.886-1.09) (0.994-1.24) (1.08-1.37)
12 -hr
F--O.-2-O3-7F--O.-24-3-7F--O.-3-01--]F-O.-35-47F-O.-424-7F0.484 7r 0.545 T 0.6107F 0.7007F 0.779
(0.185-0.222) (0.222-0.266) (0.275-0.330) (0.322-0.388) (0.383-0.462) (0.434-0.526) (0.484-0.592) (0.536-0.662) (0.605-0.759) (0.662-0.845)
24 -hr
2 -day ��
3ilay 0.049 0.059 0.074 0.085 0.100 0.113 0.125 0.138 0.156 0.170
(0.046-0.053) (0.055-0.064) (0.069-0.079) (0.079-0.091)1(0.093-0.108)11(0.104-0.121)11(0.115-0.134) (0.127-0.148) (0.142-0.168) (0.154-0.183)
4�ay 0.039 0.047 0.058 0.067 0.079 0.088 0.098 0.108 0.122 0.133
(0.036-0.042) (0.044-0.050) (0.054-0.062) (0.062-0.071) (0.073-0.084) (0.082-0.094) (0.090-0.105) (0.099-0.116) (0.111-0.131) (0.121-0.142)
0.026 0.031 0.038 0.043 0.050 0.056 0.062 0.069 0.077 0.084
7�1a (0.024-0.028) (0.029-0.033) (0.035-0.040) (0.040-0.046) (0.047-0.054) (0.052-0.060) (0.058-0.067) (0.063-0.073) (0.071-0.083) (0.077-0.090)
10�Jay 0.021 0.025 0.030 0.034 0.039 0.043 0.047 0.052 0.057 0.062
(0.019-0.022) (0.023-0.026) (0.028-0.032) (0.031-0.036) (0.036-0.041) (0.040-0.046) (0.044-0.050) (0.048-0.055) (0.053-0.061) (0.057-0.066)
20�ay 0.014 0.016 0.019 0.022 0.025 0.027 0.030 0.032 0.036 0.039
(0.013-0.015) (0.015-0.017) (0.018-0.021) (0.020-0.023) (0.023-0.026) (0.026-0.029) (0.028-0.032) (0.030-0.035) (0.033-0.038) (0.036-0.041)
30�1ay 0.011 0.013 0---]F--O.-0-177F ) ( )0.020 0.021 0.023 0.025 0.027 0.029
(0.011-0.012) (0.013-0.014) (0.015-0.017 0.016-0.019 (0.018-0.021) (0.020-0.023) (0.022-0.025) (0.023-0.026) (0.025-0.029) (0.027-0.031)
45 -day 0.010 0.011 0.013 0.014 0.016 0.017 0.019 0.020 0.021 0.022
(0.009-0.010) (0.011-0.012) (0.012-0.014) (0.014-0.015) (0.015-0.017) (0.016-0.018) (0.017-0.020) (0.019-0.021) (0.020-0.023) (0.021-0.024)
60ilay 0.009 0.010 0.012 0.013 0.014 0.015 0.016 0.017 0.018 0.019
(0.008-0.009) (0.010 0.011) (0.011-0.012) (0.012-0.013) (0.013-0.015) (0.014-0.016) (0.015-0.017) (0.016-0.018) (0.017-0.019) (0.018-0.020)
t Precipitation frequency (PF) estimates in this table are based on frequency analysis of partial duration series (PDS).
Numbers in parenthesis are PF estimates at lower and upper bounds of the 90% confidence interval. The probability that precipitation frequency estimates (for a
given duration and average recurrence interval) will be greater than the upper bound (or less than the lower bound) is 5%. Estimates at upper bounds are not
checked against probable maximum precipitation (PMP) estimates and may be higher than currently valid PMP values.
Please refer to NOAA Atlas 14 document for more information.
F-0-1217F-O.-14-6--]F-O.-183---]F--0.213 0253 0.285 0.318 0.352 0.399 0.435
(0.112-0.130) (0.135-0.157) (0.170-0.198) (0.197-0.229) (0.234-0.273) (0.262-0.307) (0.292-0.343) (0.322-0.380) (0.363-0.430) (0.395-0.471)
0.070 0.084 0.105 0.121 0.144 0.161 0.179 0.198 0.224 0.244
(0.065-0.075) (0.078-0.091) (0.097-0.113) (0.113-0.131) 1(0.133-0.155)11(0.149-0.174)11(0.165-0.193)11(0.182-0.213)
Back to Too
(0.204-0.241)
(0.222-0.264)
Back to Too

100.000
Z 10.000
S
1.000
a
c
C
0.100
rp
CL
V
O1
a 0.010
PF graphical
PDS -based intensity -duration -frequency (IDF) curves
Latitude: 35.75490, Longitude: -78.6422°
0.001, i i i i i 1 1 1 1 1 1 1 1 i 1
C C C C Z L L . ,L >+ >. >1 >1 >, >, >+ >+ >.
N fit %6 N 'O -0 -0 6 .0 "0 M -0-0
k� 6 LA M 6 ''1 fV N A4 I -L 6 N 0' LA ET SD
Duration
100.000
Z 10.000
r
G
1.000
a
c
0-001, L 1 ` 1 1 1 1 1 i
1 2 5 10 25 50 100 200 500 1000
Average recurrence interval (years)
NOAA Atlas 14, Volume 2, Version 3 Created (GMT): Thu Dec 8 23:47:06 2016
Back to Top
Maps & aerials
Small scale terrain
Average recurrence
interval
(years)
— 1
2
5
10
25
50
100
200
500
1000
Duration
— 5 -min
— 2 -day
— IO -min
— 3 -day
1 "in
— 4 -day
— 30 -min
— 7 -day
— 50 -min
— 10 -day
— 2 -hr
— 20 -day
— 3 -hr
— 30 -day
— 6fir
— 45 -day
— 12 -hr
— 60 -day
-- 24 -hr

NOAA Atias 14, Volume 2, Version 3
Location name: Raleigh, North Carolina,
Latitude: 35.75460, Longitude: -78.6415°
Elevation: 242.31 R"'
Duration
1
'source: ESRI Maps
10
' source: USGS
100
POINT PRECIPITATION FREQUENCY ESTIMATES
G.M. Bonnin, D. Martin, B. Lin, T. Parzybok, M.Yekta, and D. Riley
NOAH, National Weather Service, Silver Spring, Maryland
PF tabularI PF graphical I Maps & aerials
PF tabular
PDS -based point precipitation frequency estimates with 90% confidence intervals (in inches)1
Average recurrence interval (years)
Duration
1
2 5
10
25 50
�����-
100
200 500
1000
OA08
0.476 0.547
0.6087F
0.6727F 0.720
0.767F
0.799 .8417F
0.875
5 -min
(0.373-0.445)
(0.437-0.520) (0.502-0.597)
(0.557-0.664)
(0.613-0.733) (0.653-0.784)
(0.688-0.830)
(0.717-0.872) (0.748-0.917)
(0.772-0.956)
-0.6-5-17F-0-16-17F-0-.87-6
0.973
1.07 1.15
121
1.27 1.33
1.38
10frtin
1(0.596-0.711)1(0.698-0.832)1(0.804-0.956)1(0.891-1.06)
(0.977-1.17) 1 (1.04-1.25)
1 (1.09-1.32)
1 (1.14-1.38) 1 (1.18-1.45)
1 (1.22.1.50)
0.814
0.957 1.11
1.23
1.36 1A5
1.53
1.60 1.67
1.73
15{rtin
1(0.745-0.889)1(0.878-1.05)
1 (1.02-1.21)
1 (1.13-1.34)
1 (1.24-1.48) 1 (1.32-1.58) 11
(1.38-1.67)
1 (1.44-1.74) 1 (1.49-1.83)
11 (1.52-1.89)
1.12
1.32 1.57
1.78
2.01 2.19
2.35
2.49 2.66
2.80
30{rtin (1.02-1.22)
1 (1.21-1.44) 1 (1.45-1.72)
1 (1.63-1.95)
1 (1.83-2.19) 1 (1.98-2.38) 11
(2.12-2.56)
11 (2.23-2.71) 1 (2.37-2.90)
11 (2.47-3.06)
1.39
1.66 -2-.0-2-7-25
-2 7
F -2.-6-8-7F-2-96--
--3-23-7F-3-.49-
--3.-8-2-7F--4-0
9
60{rtin
(1.27-1.52)
(1.52-1.81) 1 (1.85-2.20)
1 (2.13-2.53)
1 (2.44-2.92) 11 (2.69-3.23)
1 (2.91-3.52)
1 (3.13-3.81) 1 (3.40-4.17)
1 (3.61-4.47)
1.63
1.95 2A0
2.78
3.25 3.65
--45-2-7-454-1
4.90
5.31
2 -hr
(1.48-1.79)
(1.78-2.14) 1 (2.19-2.63)
1 (2.52-3.06)
1 (2.93-3.57) 11 (3.27-3.99)
1 (3.58-4.40)
1 (3.90-4.82) 1 (4.30-5.36)
1 (4.62-5.82)
1.73
2.07 2.55
2.99
3.53 3.99
4.45
4.92 5.56
6.11
3 -hr
(1.57-1.90)
1 (1.89-2.28) 1 (2.33-2.81)
1 (2.71-3.28)
(3.18-3.87) (3.58-4.37)
(3.96-4.87)
1 (4.35-5.38) (4.86-6.08)
(5.28-6.69)
2.07
2-A -87F--3.077F
3.59
426 4.83
5.417F
6.01 6.83
7.54
6 -hr
(1.90-2.27)
1 (2.28-2.73) 1 (2.80-3.36)
1 (3.27-3.93)
(3.86-4.65) (4.35-5.27)
(4.83-5.89)
1 (5.31-6.54) (5.96-7.43)
(6.49-8.21)
F-2.-"-7F--2.-9-2-7F-3-.6-3-7F-4-.2-7-75.117
F -55.8 -37F
-6-.5-77F-7-35--]
F8.44
9.39
12 -hr
(2.23-2.68)
1 (2.68-3.21) 1 (3.31-3.97)
1 (3.88-4.67)
1 (4.61-5.57) 1 (5.23-6.34)
1 (5.83-7.14)
1 (6.45-7.98) (7.29-9.14)
(7.98-10.2)
2.89
3.49 4.39
5.10
6.07 6.84
7.63
8.44 9.57
10.4
24 -hr
(2.69-3.12)
1 (3.25-3.77) 1 (4.08-4.74)
1 (4.72-5.50)
1 (5.60-6.55) (6.30-7.37)
(7.00-8.22)
1 (7.73-9.11) (8.72-10.3)
(9.49-11.3)
F--3.-3-5-7F--4-0-47F--S.-04-
-5.-8-3-7F--6.90
7.74
8.61
9.51 10.7
11.7
2{lay
(3.11-3.61)
(3.75-4.35) (4.68-5.42)
(5.40-6.27)
(6.37-7.42) ( 7.14-8.34)
(7.92-9.28)
1 (8.72-10.2) 1 (9.80-11.6)
11 (10.6-12.7)
F-355-577-4.2
7 5.30
6.11
722 8.10
9.01
9.94 -1-1.2-7F-112.-27
3�lay (3.31-3.81)
1 (3.98-4.58) 1 (4.93-5.69)
1 (5.68-6.56)
1 (6.69-7.75) 1 (7.49-8.70)
1 (8.29-9.67) 11
(9.12-10.7) 1 (10.2-12.1)
(11.1-13.2)
3.7-5-7-4.50
5.57
6.40
7.55 8.467F
9.407F
10.47F 11.7
12.7
4 -day
(3.50-4.02)
1 (4.20-4.82) 1 (5.19-5.96)
1 (5.96-6.85)
1 (7.00-8.08) 1 (7.83-9.06)
1 (8.67-10.1) 11
(9.53-11.1) 1 (10.7-12.5)
(11.6-13.7)
4.35
5.19 6.33
7.24
8.48 9.47
10.5
11.5 13.0
14.1
play (4.07-4.64)
(4.86-5.54) (5.92-6.76)
(6.76-7.72)
(7.90-9.05) 1 (8.80-10.1)
1 (9.71.11.2)
(10.6-12.3) 1 (11.9-13.9)
1 (12.9-15.1)
4.96
5.90 7.11
8.05
9.32 10.3
11.3
12.4 13.8
14.8
10�1ay
(4.65-5.29)
(5.54-6.29) (6.66-7.57)
(7.52-8.57)
(8.70-9.93) (9.61-11.0)
(10.5-12.1)
(11.4-13.2) (12.7-14.7)
(13.6-15.9)
6.65
7.85 929
10.4
12.0
13.2
14.4
15.6
17.3
18.5
20•day
(6.25-7.08)
(7.38-8.37) (8.72-9.89)
(9.77-11.1)
(11.2-12.7)
(12.3-14.0)
(13.4-15.3) 11
(14.5-16.6)
(15.9-18.4)
(17.1-19.8)
F-85.2-6-7-90.
7 2 7 F 11-.3-T--1-2.-67F--14.2-7F--'5.4
16.7
17.9
19.6
20.8
30ilay
(7.78-8.77)
1 (9.14-10.3) 1 (10.6-12.0)
1 (11.8-13.3)
1 (13.3-15.1)
1 (14.4-16.4)
1 (15.6-17.7)
1 (16.7-19.1)
1 (18.2-20.9) 11
(19.3-22.3)
10.5
12.3 14.1
15.5
17.3
18.7
T 2-0.077-21.-37F
23.0-77-24--].3
45�day
(9.99-11.1)
(11.7-13.0) (13.4-14.9)
(14.7-16.4)
(16.4-18.3)
(17.6-19.7)
(18.8-21.1)
( 20.0-22.5)
( 21.5-24.3)
(T
12.6
14.7 16.7
18.2
21.6
23.0
24.3
26.1
27.5
20.1
60ilay
( 12.0-13.3)
(14.0-15.5) (15.8-17.6)
(17.2 19.2)
-21.2)
(19.0.4-22.8)
(20
(21.7-24.3)
(22.9-25.7)
(24.5- 27.6)
(25 .7-29.1 )
1 Precipitation frequency (PF) estimates in this table are based on frequency analysis of partial duration series (PDS).
Numbers in parenthesis are PF estimates at lower and upper bounds of the 90% confidence interval. The probability that precipitation frequency estimates (fora
given duration and average recurrence interval) will be greater than the upper bound (or less than the lower bound) is 5%. Estimates at upper bounds are not
checked against probable maximum precipitation (PMP) estimates and may be higher than currently valid PMP values.
Please refer to NOAA Atlas 14 document for more information.
Back to Too

PF graphical
PDS -based depth -duration -frequency (DDF) curves
Latitude: 35.7546°, Longitude: -78.64150
30
25
r-
5
0
C G C C C t t Z t L >+ ?+T T ?r 7. a Ma
E E E E r:, r1r �b v v -a -6 -`00 -`00 100 1°o v
to p A O O N N f}t ^ O O O 1 i O
rl N M cr ko
Duration
30
25
r 20
C
CL
d
v
0 15
41
a 10
LU
CL
_.
0
1 2 5 10 25 50 100 200 500 1000
Average recurrence interval (years)
NOAA Atlas 14, Volume 2, Version 3 Created (GMT): Mon Dec 12 16:54:512016
Back to Too
Maps & aerials
Small scale terrain
Average recurrence
interval
(Years)
— 1
2
5
10
25
50
100
200
500
1000
Duration
— 5 -min
— 2 -day
— IO -min
— 3 -day
15 -min
— 4 -day
— 30 -min
— 7 -day
— 60 -min
— 10 -day
— 2 -hr
— 20 -day
— 3 -hr
— 30 -day
— "r
— 45 -day
— 12 -hr
— 60 -day
— 24 -hr

Large scale map
Nt
Greensboro I
Aocky
0 Durham Mount
North ' pGreenville
Carolina
ad.
F etteville
0
100km Jacks
6 m
i ,
Large scale aerial

Pabst Design Group, PA
911 Paverstone Drive, Ste. E
Raleigh, NC 27615
XI. Erosion Control Calculations
Stormwater Impact Analyses
1938 S Wilmington St
Raleigh, North Carolina
PDG: 339-16
Raleigh Concrete, LLC
512 Nowell Raod
Raleigh, NC 27607

Selection of Sediment Control Measure
Total Drainage Area
Okay
Temporary Sediment Trap
Okay
Rock Dam,
Okay
Skimmer Sediment Basin
Okay
Temporary Sediment Basin
Disturbed Area (Acres)
3.84 Peak Flow from 25 -year Storm (cfs)
User entry
Calculated Value
C =(Unimproved cleared area) - Source: Raleigh Stormwater Manual
125 = M
Source: NOAA Atlas 14, Vol. 2, Ver. 3 - T = 5 minutes
A= 1.23

Skimmer Basin
Okay
0.45 Disturbed Area (Acres)
3.84 Peak Flow from 25 -year Storm (cfs)
810
Required Volume ft 3
1669
Required Surface Area ft 2
28.9
Suggested Width ft
57.8
Suggested Length ft
Trial Top Width at Spillway Invert ft
Trial Top Length at Spillway Invert ft
Trial Side Slope Ratio Z:1
Trial Depth ft (2 to 3.5 feet above grade)
27 Bottom Width ft
40 Bottom Length ft
1080 Bottom Area ft 2
2739 Actual Volume ft 3 Okay
1680 Actual Surface Area ft 2 Okay
Trial Weir Length ft
Trial Depth of Flow ft
5.3 Spillway Capacity cfs Okay
Skimmer Size (inches)
0.208 Head on Skimmer (feet)
Orifice Size (1/4 inch increments)
2.60 Dewatering Time (days)
Suggest about 3 days

Pabst Design Group, PA
911 Paverstone Drive, Ste. E
Raleigh, NC 27615
XII. Erosion Control Drainage Area Map
ix
Stormwater Impact Analyses
1938 S Wilmington St
Raleigh, North Carolina
PDG: 339-16
Raleigh Concrete, LLC
512 Nowell Raod
Raleigh, NC 27607