20100012 Ver 2_Stormwater Info_20111021

WITHERS &- RAVENEL
ENGINEERS I PLANNERS I SURVEYORS
iii MacKenan Drive
CARY, NORTH CAROLINA, 27511
[phone]
FAX [phone]oo8
To: Wetlands and Stormwater Branch
NCDENR
512 N. Salisbury Street, Stn Floor
Raleigh, North Carolina 276o4
WE ARE SENDING YOU
? Shop Drawings
? Copy of Letter
® Attached
® Prints
? Change order
LETTER OF T° ° NSWITAL
DATE 10/20/11 JOB NO 02100371
ATTENTION Annette Lucas
PHONE# 8o7-6381
RE: Water Garden Village
©_OC)?

D

;fir ; y

W-TLMDSAW STORMWATER BRANCH
? Under separate cover via the following items:
? Plans ? Samples ? Specifications
? Diskette ?
COPIES DATE NO. DESCRIPTION
1 LS-VFS Supplement
1 Construction Plans
1 Supporting Calculations
1 Executed O&M Agreement

THESE ARE TRANSMITTED as checked below:
? For approval ? Approved as submitted
® For your use ? Approved as noted
? As requested ? Returned for corrections
? For review and comment ?
? FOR BIDS DUE 20 ? PRINTS RETURNED AFTER LOAN TO US
REMARKS:
COPYTO: File
? Resubmit
? Submit
? Return
_ copies for approval
copies for distribution
corrected prints
SIGNED: Ken Jesneck, PE
lfenclosures are not as noted, kindly notify us at once.
WITHERS &" RAVEN EL
ENGINEERS I PLANNERS I SURVEYORS
October 20, 2011
Ms. Annette Lucas, PE
North Carolina Division of Water Quality
Wetlands and Stormwater Branch
512 N. Salisbury Street, 9`h Floor
Raleigh, North Carolina 27604
Re: Additional Information for Buffer Authorization Application
Water Garden Village
Raleigh, North Carolina
W&R Project 0210371
Dear Ms. Lucas:
Please find attached a completed Level Spreader-Vegetated Filter Strip Supplement form. I am also including
a set of Construction Plan, supporting documents with calculations for the stormwater management system,
and an executed Operations and Maintenance Agreement. The City of Raleigh has conditional approved the
stormwater management system, with the condition that the buffer authorization be issued by DWQ.
If you need additional information or additional copies of this information, please contact me at 919-469-
3340 or email at [e-mail].
Sincerely,
WITHERS AVENEL
Kenneth L. jesneck, PE
Project Manager
111 MacKenan Drive I Cary, NC 275111 tel.: [phone] fax: [phone] www.withersravenel.com I License No. C-0832
1410 Commonwealth Drive I Suite 1011 Wilmington, NC 28403 1 tel: [phone] fax: [phone]
7011 Albert Pick Road I Suite G I Greensboro, NC 27409 1 tel: [phone] fax: [phone]
Red triangles at the upper right hand comer indicate design comments
Please complete the yellow shaded items.
O?O? W ATE9OG
W
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
401 CERTIFICATION APPLICATION FORM
LEVEL SPREADER - VEGETATED FILTER STRIP (LS-VFS) SUPPLEMENT
This form must be completely filled out printed, initialed, and submitted.
L PROJECT INFORMATION
Project name Water Garden Village
Contact name Ken Jesneck, PE
Phone number 919-469-3340
Date September 13, 2011
Drainage area number Site
II. DESIGN INFORMATION
The purpose of the LS-VFS Pollutant removal: 40% TSS, 30% TN, 35% TP
Stormwater enters LS-VFS from The drainage area
Type of VFS Engineered filter strip (graded & sodded, slope < 8%)
Explanation of any "Other" responses above
If Stormwater Enters the LS-VFS from the Drainage Area
Drainage area
Impervious surface area
Percent impervious
Rational C coefficient
Peak flow from the 1 in/hr storm
Time of concentration
Rainfall intensity, 10-yr storm
Peak flow from the 10-yr storm
Design storm
Maximum amount of flow directed to the LS-VFS
Is a flow bypass system going to be used?
Explanation of any "Other" responses above
If Stormwater Enters the LS-VFS from a BMP
Type of BMP
Peak discharge from the BMP during the design storm
Peak discharge from the BMP during the 10-year storm
Maximum capacity of a 100-foot long LS-VFS
Peak flow directed to the LS-VFS
Is a flow bypass system going to be used?
Explanation of any "Other" responses above
LS-VFS Design
Forebay surface area
Depth of forebay at stormwater entry point
Depth of forebay at stormwater exit point
Feet of level lip needed per cfs
Computed minimum length of the level lip needed
Length of level lip provided
Width of VFS
Elevation at downslope base of level lip
Elevation at the end of the VFS that is farthest from the LS
166,835 fe
106,286 fe
63.71 %
0.73
2.80 cfs
5.00 min
7.08 in/hr
19.79 cfs
1 inch/hour storm
2.8 cfs
Y (Y or N)
Pick one:
Do not complete this section of the form.
cfs
cfs Do not complete this section of the form.
10 cfs
cfs Do not complete this section of the form.
(Y or N)
Underground Detention System
215 sq ft
24 in
12 in
10 ft/cfs
28 ft
30 ft
30 ft
391.25 fmsl
390.00 fmsl
Forebay is adequately sized.
Depth is appropriate.
Depth is appropriate.
Form SW401 - LS-VFS - 29Nov2010 - Rev.8 page 1 of 3
Slope (from level lip to the end of the VFS)
Are any draws present in the VFS?
Is there a collector Swale at the end of the VFS?
Bypass System Design (if applicable)
Is a bypass system provided?
Is there an engineered flow splitting device?
Dimensions of the channel (see diagram below):
M
B
W
y (flow depth for 10-year storm)
freeboard (during the 10-year storm)
Peak velocity in the channel during the 10-yr storm
Channel lining material
Does the bypass discharge through a wetland?
Does the channel enter the stream at an angle?
Explanation of any "Other' responses above
4.17 %
N (Y or N) OK
N (Y or N)
Y (Y or N)
N (Y or N)
3.00 ft
5.00 ft
22.00 ft
1.95 ft
1.00 ft
0.96 ft/sec
Pick one:
N (Y or N)
Y (Y or N)
t\'
N ?
v(diumig the t 0-yt,tonu) I
t L --------- ----------1
hi Al
1 B
III. REQUIRED ITEMS CHECKLIST
EDIT Please indicate the page or plan sheet numbers where the supporting documentation can be found. An incomplete submittal package will result
in a request for additional information. This will delay final review and approval of the project. Initial in the space provided to indicate the following
design requirements have been met. If the applicant has designated an agent, the agent may initial below. If a requirement has not been met, attach
justification.
Requried Item:
1. Plans (1" - 50' or larger) of the entire site showing:
- Design at ultimate build-out,
Off-site drainage (if applicable),
Delineated drainage basins (include Rational C coefficient per basin),
Forebay (if applicable),
High flow bypass system,
Maintenance access,
Proposed drainage easement and public right of way (ROW), and
Boundaries of drainage easement.
2. Plan details (1" = 30' or larger) for the level spreader showing:
- Forebay (if applicable),
High flow bypass system,
One foot topo lines between the level lip and top of stream bank,
Proposed drainage easement, and
Design at ultimate build-out.
Form SW401 - LS-VFS - 29Nov2010 - Rev.8 page 2 of 3
3. Section view of the level spreader (1" = 20' or larger) showing:
- Underdrain system (if applicable),
Level lip,
Upslope channel, and
Downslope filter fabric.
4. Plan details of the flow splitting device and supporting calculations (if applicable).
5. A construction sequence that shows how the level spreader will be protected from
sediment until the entire drainage area is stabilized.
6. If a non-engineered VFS is being used, then provide a photograph of the VFS showing
that no draws are present.
7. The supporting calculations.
8. A copy of the signed and notarized operation and maintenance (0&M) agreement.
Form SW401 - LS-VFS - 29Nov2010 - Rev.8 page 3 of 3
Permit Number:
(to be provided by DWQ)
Drainage Area Number:
Filter Strip, Restored Riparian Buffer and Level Spreader
Operation and Maintenance Agreement
I will keep a maintenance record on this BMP. This maintenance record will 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 removal efficiency of the BMP.
Important maintenance procedures:
- Immediately after the filter strip is established, any newly planted vegetation
will be watered twice weekly if needed until the plants become established
(commonly six weeks).
- Once a year, the filter strip will be reseeded to maintain a dense growth of
vegetation
- Stable groundcover will be maintained in the drainage area to reduce the
sediment load to the vegetation.
- Two to three times a year, grass filter strips will be mowed and the clippings
harvested to promote the growth of thick vegetation with optimum pollutant
removal efficiency. Turf grass should not be cut shorter than 3 to 5 inches and
may be allowed to grow as tall as 12 inches depending on aesthetic requirements
(NIPC,1993). Forested filter strips do not require this type of maintenance.
- Once a year, the soil will be aerated if necessary.
- Once a year, soil pH will be tested and lime will be added if necessary.
After the filter strip is established, it will be inspected quarterly and within 24 hours
after every storm event greater than 1.0 inch (or 1.5 inches if in a Coastal County).
Records of operation and maintenance will be kept in a known set location and will be
available upon request.
Inspection activities shall be performed as follows. Any problems that are found shall
be repaired immediately.
BMP element: Potential problem: How I will remediate the problem:
The entire filter strip Trash/debris is present. Remove the trash/debris.
system
The flow splitter device The flow sputter device is Unclog the conveyance and dispose
(if applicable) clog ed. of an sediment off-site.
The flow splitter device is Make any necessary repairs or
damaged. replace if damage is too large for
repair.
Form SWU401-Level Spreader, Filter Strip, Restored Riparian Buffer O&M-Rev.3 Page 1 of 3

BMP element: Potential problem: How I will remediate the problem:
The swale and the level The swale is clogged with Remove the sediment and dispose
lip sediment. of it off-site.
The level lip is cracked, Repair or replace lip.
settled, undercut, eroded or
otherwise damaged.
There is erosion around the Regrade the soil to create a berm
end of the level spreader that that is higher than the level lip, and
shows stormwater has then plant a ground cover and
bypassed it. water until it is established. Provide
lime and a one-time fertilizer
application.
Trees or shrubs have begun Remove them.
to grow on the swale or just
downslo e of the level lip.
The bypass channel Areas of bare soil and/or Regrade the soil if necessary to
erosive gullies have formed. remove the gully, and then
reestablish proper erosion control.
Turf reinforcement is Study the site to see if a larger
damaged or ripap is rolling bypass channel is needed (enlarge if
downhill. necessary). After this, reestablish
the erosion control material.
The filter strip Grass is too short or too long Maintain grass at a height of
(if applicable). approximately three to six inches.
Areas of bare soil and/or Regrade the soil if necessary to
erosive gullies have formed. remove the gully, and then plant a
ground cover and water until it is
established. Provide lime and a
one-time fertilizer application.
Sediment is building up on Remove the sediment and
the filter strip. restabilize the soil with vegetation if
necessary. Provide lime and a one-
time fertilizer application.
Plants are desiccated. Provide additional irrigation and
fertilizer as needed.
Plants are dead, diseased or Determine the source of the
dying. problem: soils, hydrology, disease,
etc. Remedy the problem and
replace plants. Provide a one-time
fertilizer application.
Nuisance vegetation is Remove vegetation by hand if
choking out desirable species. possible. If pesticide is used, do not
allow it to get into the receiving
water.
The receiving water Erosion or other signs of Contact the NC Division of Water
damage have occurred at the Quality local Regional Office, or the
outlet. 401 Oversight Unit at 919-733-1786.
Form SWU401-Level Spreader, Filter Strip, Restored Riparian Buffer O&M-Rev.3 Page 2 of 3
.
Permit Number:
(to be provided by D1,17Q)
I acknowledge and agree by my signature below that I am responsible for the
performance of the maintenance procedures listed above. I agree to notify DWQ of any
problems with the system or prior to any changes to the system or responsible party.
Project narne:Water Garden Village
BMP drainage area rurnaber:Site
Print name:Natalie Bri
Title:Vice President, Rental Development
Address. 113 South Wilmington Street, Raleigh North Carolina 27601
Phone:[phone]
Signature: 4' 1 (1 VVK-,
i
Date:
Note: The legally responsible party should not be a homeowners association unless more than 50% of
the lots have been sold and a resident of the subdivision has been named the president.
a Notary Public for the State of
County of do hereby certify that
Epersonally appeared before me this
day of and acknowledge the due execution of the
forgoing filter strip, riparian buffer, and/or level spreader maintenance requirements.
Witness my hand and official seal,
SAUNDRA R HARPER
Notary Public
Durham County
North Carolina
MY Commission Expires Oct 1, 2016
SEAL
My commission expires
Form SWU40 t-Level Spreader, Filter Strip, Restored Riparian Buffer O&M-Rev.3 Page 3 of 3
WITHERS RAVEN EL
io -ou1J. U2-
Water Garden Village
K1 V$MbiSTORIOWATERaRANCH
Storm Water Management Report
Stormwater System Support Calculations
Prepared For:
DHIC, Inc.
113 South Wilmington Street
Raleigh, North Carolina 276o1
PHONE: [phone]
Attn: Natalie Britt
Prepared By:
WITHERS & RAVENEL, INC
ill MacKenan Drive
Cary, North Carolina 27511
September 2011
W&R Project No. 2100371.00
?. 4Pt )i
? ty
t r
/ f S
1
• 9 a
SIP

Water Garden Village
Stormwater Management Report
Raleigh, North Carolina
INTRODUCTION
The purpose of Storm Water Management Report is to document pre- and post-development peak
stormwater runoff rates for the 2-year, io-year, 25-year, and loo-year design storm events from the
site. The goal is to ensure that the peak outflows from the proposed development area during the 2-
year and io-year storms do not exceed the pre-development outflows during the same storms.
The site is located in Raleigh, NC, on the north side of Glenwood Avenue between Toscana Drive and
• Country Trail. The 11.31 acre site lies within the Neuse River basin. The existing site is a former office
complex with the remaining portions wooded. A stream traverses the southern boundary roughly
parallel to Glenwood Avenue. The site is currently being subdivided into three lots, with Lot 1 being
developed first. The existing impervious surface area of the parent tract will be utilized as a credit
• towards new impervious surface area. Existing impervious surface will be utilized as it exists on
each of the two lots, ie 0.13 acres to Lot 1 and 1.2 acres to Lot 2. This Stormwater Management
Report addresses only Lot 1. Lot 1 is 4.41 acres.
An underground detention system is being proposed to meet the stormwater management goals for
this property. A level spreader with a vegetated filter strip is also being proposed as a BMP device
• for water quality and nitrogen reduction. All BMPs are located within the proposed Lot 1 and will not
• be shared with Lot 2.
NITROGEN
In accordance with the City of Raleigh stormwater ordinances, nitrogen in excess of 3.6 pounds per
year must be reduced prior to discharge to the surface waters. For commercial sites, as a Water
• Garden Village, a BMP must be used to treat the nitrogen when the export is greater than 1o pounds
per acre per year. Utilizing the 0.13 acres of existing impervious surface acre, the Nitrogen
Calculations for Expansion was used to determine the nitrogen export from Lot 1. The proposed
impervious surface area for the Water Garden Village is 2.41 acres. The level spreader with a
• vegetated filter strip proposes a 30% nitrogen reduction. Based on the calculations, the nitrogen
export for the Water Garden Village is 7.50 pounds per acre per year. Thus, the Developer will buy
down the nitrogen to the 3.6 pound threshold. The calculations are attached.
WATER QUANTITY CONTROL
• The City of Raleigh requires that new development control the post development 2-year and zo-year
• peak storm events to the peak flows of the predevelopment condition per outlet. The results of the
peak flow analysis are attached. Based on the results, the project will be required to detain the
peak flows. An underground detention system is being proposed.
The Site is divided into two outlets. One is to the north and the other is to the south. The drainage
area for the northern outlet is actually be reduced in size since all the impervious surfaces are being
• captured, except for a small portion of the entrance. Based on the analysis, the northern outlet does
• not require any detainage.
The bulk of the impervious surface area is located in the southern drainage basin. Based on the
• analysis, the peak storms will need to be detained to meet the City of Raleigh requirements. Since
not all impervious surface area is being captured, the underground detention system will be design
such that the overall peaks flows discharging from the Site meet the requirements.

• Water Garden Village W&R Project 0210371.00
Stormwater Management Report September 13, 2011
•
• Water Garden Village
• Stormwater Management Report
Raleigh, North Carolina
METHODOLOGY
The stormwater study was conducted using the natural drainage features as depicted by existing
field surveys. Proposed drainage areas were based on field survey data and proposed development
• within the drainage areas.
The scope of work included the following analyses:
Hydrology
• ? Simulation of the 2-year, 1o-year, 25-year, and ioo-year rainfall events for the Raleigh,
NC area
? Formulation of the 2-year, io-year, 25-year, and loo-year flood hydrographs for the pre-
and post-development drainage areas
Hydraulic
• ? Routing the 2-year, io-year, 25-year, and loo-year flood hydrographs for pre-
development runoff from the site.
? Routing the 2-year, 1o-year, 25-year, and loo-year flood hydrographs for post-
development runoff through the proposed wetland and bioretention area.
r The results of the hydrology calculations are used in the hydraulic analyses. The hydraulic design
• requires the development of a stage-storage and stage-discharge function for the proposed
• impoundments. The rainfall/runoff hydrographs, stage-storage and stage-discharge functions have
been compiled to create a routing computer simulation model using Haestad Methods PondPack
vio.o software. This PondPack model was then used to assess the peak water surface elevations for
• the design rainfall events. The PondPack modeling results are provided as appendices to this
report.
• HYDROLOGY
The SCS Method was used to develop runoff hydrographs for the 24-hour duration rainfall curves
using the NOAA Atlas 14 rainfall data for Raleigh-Durham International Airport for the 2-year, io-year,
• 25-year and loo-year storm events. This method requires three basic parameters: a curve number
(CN), time of concentration (Q, and drainage area.
• Curve numbers were based on soil type and land use. Soil types were delineated from the Soil
• Survey of Wake County, North Carolina (November 1970). Land use for existing conditions was based
on the most recent Wake County aerial photographs and field observations. Existing land uses were
entered into the pre and post development models to ensure that the impoundment was adequately
. sized. Post development land use is based on the proposed site plan. The curve numbers used in
this study are listed in the appendix of this report.
• Times of concentration were calculated using methods described in the SCS publication "Urban
Hydrology for Small Watersheds, TR-55" and based on Wake County topographic maps and field
survey data. The post-development time of concentration was calculated for the drainage areas that
are piped to the storage areas based on the flow time through the piped drainage systems and small
areas of sheet flow. The breakdown of the time of concentrations and the calculated values are
found in the appendices of this report.
• Water Garden Village W&R Project 0210371.00
Stormwater Management Report September 13, 2011
0
Water Garden Village
Stormwater Management Report
Raleigh, North Carolina
HYDRAULICS
Computer simulated reservoir routing of the 2-year, 1o-year, 25-year, and ioo-year design storms
utilized stage-storage and stage-discharge functions. Stage-storage functions were derived from the
characteristics of the proposed underground detention system. A non-linear regression relation for
surface area versus elevation was derived for each basin. This relation estimates the incremental
volume of each basin to the stage or elevation of the basin. Stage-discharge functions were
developed to size the proposed outlet structures.
CONCLUSIONS
Based on the routing study, the underground detention system can be designed to achieve the
desired peak flow. The attached calculation and PondPack output files contain inflow and outflow
summaries for Lot i.
PEAK FLOW SUMMARY (OVERALL)
Northern Outlet
Qpeak Outflow Qpeak Outflow
Storm Event Pre Post Development
Development
2-Year 2.64 cfs 0.91 cfs
1o-Year 3.25 cfs 1.12 cfs
Southern Outlet

vent Qpeak Outflow
Pre
Development Qpeak Outflow
Post
Development Qpeak OUtflOW
Post Development
W/Storage
ar
F 8.69 cfs 1o.8 cfs 5.36 cfs
ar 1o.68 cfs 16.3 cfs 8.86 cfs
225-Year N/A 18.8 cfs 16.3 cfs
ear N/A 21.8 cfs 25.4 cfs
Water Garden Village W&R Project 0210371.00
Stormwater Management Report September 13, 2011
Water Garden Village
Stormwater Management Report
Raleigh, North Carolina
Storm Drainage Methodology:
Pipe Sizing
The storm drainage system consists of a series of structures and pipes to convey storm drainage
along the roadways and alleys to a single outlet point. The discharge of the storm drainage system
is into the unnamed tributary of Turkey Creek.
The storm drainage pipes were sized using a computer program called "Hydraflow" by Autodesk.
"Hydraflow" utilizes both the Manning equation for pipe flow and the Rational Method for flow
quantity. The input parameters required for the "Hydraflow" to operate include the rainfall
intensity, a runoff coefficient ("C" factor) that describes the impervious surface of the drainage area,
the actual drainage area to each inlet structure, the pipe diameter and slope, and the type of
material of the pipe as presented by the Mannings "n" value for the specific pipe material. The
rainfall intensity, or design storm, is based on historical information collected at the Raleigh-
Durham area and the time of concentration to peak flow each drainage area. The time of
concentration is calculated for each drainage area for a specific inlet structure. Figure DA has been
included to indicate the drainage area and "C" factor for each inlet structure.
The input parameters and assumptions are as follows:
Design Storm = 10-year
Time of Concentration = For design, 0.01 minutes has been assumed.
Rainfall Intensity = 7.08 in/hr for 5 minute duration
C Coefficient = based on impervious surface within drainage area to inlet
Mannings "n' = 0.013 for RCP
Minimum pipe diameter = 15"
Headloss calculated by AASHTO method assumed as smooth wall finish
Minimum pipe slope = 0.005 ft/ft, or 0.5%
Inlets assumed to capture 100% of runoff for design of pipe system
Hydraulic grade line is to remain within the pipe for 10-yr storm event.
Pipe sizing is independent of the spacing of inlet structures. The following steps are used in the
design process. Please note that the Autodesk program computes many of the data needs.
• Determine the drainage area for each inlet.
• Determine the runoff coefficient for each inlet.
• Determine the time of concentration, rainfall intensity, and the corresponding flow using
the Rational Method for each inlet.
• Select a pipe diameter starting with a 15 inch diameter pipe.
• Select pipe slope of pipe of interest, using corresponding with slope of street.
• Apply Manning's equation to determine whether pipe is of sufficient diameter for flow and
slope.
• Continue from upstream to downstream, adding flow from upstream pipe and inlet to
design the pipe size of the downstream pipe.
Results of pipe sizing are included with this report.
Water Garden Village W&R Project 0210371.00
Stormwater Management Report September 13, 2011
Water Garden Village
Stormwater Management Report
Raleigh, North Carolina
Inlet Spacing/Gutter Spread
As a requirement for approval of the Preliminary Subdivision Plat and Site Plan, a check was
performed on the gutter spread of the adjacent storm inlet in Marvino Lane. The standard inlet for
this project is the City of Raleigh type of curb inlet. Gutter spread is derived using the Manning's
equation with input parameters and include the gutter slope, the cross slope of the street,
Manning's n factor for concrete, the flow at the design storm, and the depth of flow at the curb.
The input parameters and assumptions are as follows;
• Rainfall Intensity for the design storm = 5.76 in/hr (2-year storm)
• Runoff coefficient (C) = based on impervious surface within drainage area to inlet
• Mannings "n' = 0.013 for RCP
• Cross slope of street = 0.0208 ft/ft (1/4in/ft) for normal crown
• Gutter slope = slope of centerline of street, or slope of warped gutter when in a sag
• Gutter depth = 5 in maximum depth
• Gutter spread =1/2 travel lane
• For sags, a 50% clogging factor of the inlet is assumed.
• Spacing is a maximum of 400 feet
The spread in the alleys has been calculated using the methodology presented in HEC-22. The
calculations to determine the spread are embedded into a spreadsheet. The predevelopment and
post development gutter spread for this inlet structure is attached.
Water Garden Village W&R Project 0210371.00
Stormwater Management Report September 13, 2011
Water Garden Village
Stormwater Management Report
Raleigh, North Carolina
POND/SITE OUTFLOW
CALCULATIONS
Water Garden Village W&R Project 0210371.00
Stormwater Management Report September 13, 2011
Job File: K:\10\10-0370\100371-Water Garden\H-H\PondPack Models\WGV.PPW
Rain Dir: K:\10\10-0370\100371-Water Garden\H-H\PondPack Models\
JOB TITLE
Project Date: 9/13/2011
Project Engineer: Ken Jesneck, PE
Project Title: Water Garden Village
Project Comments:
Final Design
SIN: Bentley Systems, Inc.
Bentley PondPack (10.00.027.00) 3:02 PM 9/13/2011
Table of Contents
Table of Contents
i
********************** MASTER SUMMARY **********************
Watershed....... Master Network Summary ............. 1.01
******************** OUTLET STRUCTURES *********************
Outlet 2........ Outlet Input Data .................. 2.01
Composite Rating Curve ............. 2.04
SIN:
Bentley PondPack (10.00.027.00)
3:02 PM
Bentley Systems, Inc.
9/13/2011
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Type.... Master Network Summary Page 1.01
Name.... Watershed
File.... K:\10\10-0370\100371-Water Garden\H-H\PondPack Models\WGV.ppw
MASTER DESIGN STORM SUMMARY
Network Storm Collection: RDU NOAA 14 Desi
Total
Depth
Return Event in
2 3.4400
10 4.9800
25 5.9000
100 7.3700
1 3.0000
Rainfall
Type
----------------
Time-Depth Curve
Time-Depth Curve
Time-Depth Curve
Time-Depth Curve
Synthetic Curve
RNF ID
RDU NOAA 2yr
RDU NOAA l0yr
RDU NOAA 25yr
RDU NOAA 100yr
TypeII 24hr
MASTER NETWORK SUMMARY
SCS Unit Hydrograph Method
(*Node=Outfall; +Node=Diversion;)
(Trun= HYG Truncation: Blank=None; L=Left; R=Rt; LR=Left&Rt)
Max
Return HYG Vol Qpeak Qpeak Max WSEL Pond Storage
Node ID Type Event ac-ft Trun hrs
-- cfs
-
----
- ft ac-ft
----
----------
-----------------
FROM OFFSITE ----
AREA ------ --
2 --------
.055 -- ------
-
12.1000 -
-
1.16 --
--
--
FROM OFFSITE AREA 10 .090 12.1000 1.64
FROM OFFSITE AREA 25 .111 12.1000 1.85
FROM OFFSITE AREA 100 .145 12.1000 2.12
FROM OFFSITE AREA 1 .045 11.9000 .82
OFFSITE AREA 2 .025 12.1000 .49
OFFSITE AREA 10 .053 12.1000 1.00
OFFSITE AREA 25 .073 12.1000 1.28
OFFSITE AREA 100 .106 12.1000 1.66
OFFSITE AREA 1 .018 12.0000 .29
*OUT 10 JCT 2 .754 12.3000 6.68
*OUT 10 JCT 10 1.279 12.3000 9.84
*OUT 10 JCT 25 1.605 12.3000 16.75
*OUT 10 JCT 100 2.136 12.2000 26.48
*OUT 10 JCT 1 .610 12.1000 5.77
SIN: Bentley Systems, Inc.
Bentley PondPack (10. 00.027.00) 3:02 PM 9/13/2011
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Type.... Master Network Summary Page 1.02
Name.... Watershed
File.... K:\10\10-0370\100371-Water Garden\H-H\PondPack Models\WGV.ppw
MASTER NETWORK SUMMARY
SCS Unit Hydrograph Method
(*Node=Outfall; +Node=Diversion;)
(Trun= HYG Truncation: Blank=None; L=Left; R=Rt; LR=Left&Rt)
Max
Return HYG Vol Qpeak Qpeak Max WSEL Pond Storage
Node
- ID
------------ Type
---- Event ac-ft Trun
- hrs cfs ft ac-ft
----
POND
10 IN
POND ------
2 --
-------
.729 ---------
12.1000 --------
11.99 -------- ------------
POND 10 IN POND 10 1.226 12.1000 17.94
POND 10 IN POND 25 1.532 12.1000 20.69
POND 10 IN POND 100 2.030 12.1000 23.79
POND 10 IN POND 1 .592 12.0000 9.77
POND 10 OUT POND 2 .729 12.3000 6.52 400.14 .131
POND 10 OUT POND 10 1.226 12.3000 9.50 402.61 .238
POND 10 OUT POND 25 1.532 12.3000 16.31 403.00 .252
POND 10 OUT POND 100 2.030 12.2000 25.44 403.37 .263
POND 10 OUT POND 1 .592 12.1000 5.67 399.30 .094
POST DEVELOPMENT AREA 2 .674 12.1000 10.82
POST DEVELOPMENT AREA 10 1.136 12.1000 16.30
POST DEVELOPMENT AREA 25 1.421 12.1000 18.84
POST DEVELOPMENT AREA 100 1.885 12.1000 21.68
POST DEVELOPMENT AREA 1 .547 12.0000 9.08
SIN:
Bentley PondPack (10.00.027.00)
3:02 PM
Bentley Systems, Inc.
9/13/2011
Type.... Outlet Input Data
Name.... Outlet 2
Page 2.01
File.... K:\10\10-0370\100371-Water Garden\H-H\PondPack Models\WGV.ppw
REQUESTED POND WS ELEVATIONS:
Min. Elev.= 395.83 ft
Increment = .25 ft
Max. Elev.= 405.03 ft
OUTLET CONNECTIVITY
---> Forward Flow Only (UpStream to DnStream)
<--- Reverse Flow Only (DnStream to UpStream)
<---> Forward and Reverse Both Allowed
Structure No. Outfall El, ft E2, ft
Orifice-Circular 00 ---> CO 395.830 405.030
Weir-Rectangular WO ---> CO 402.500 405.030
Culvert-Circular CO ---> TW 395.730 405.030
TW SETUP, DS Channel
SIN: Bentley Systems, Inc.
Bentley PondPack (10.00.027.00) 3:02 PM 9/13/2011
Type.... Outlet Input Data
Name.... Outlet 2
Page 2.02
File.... K:\10\10-0370\100371-Water Garden\H-H\PondPack Models\WGV.ppw
OUTLET STRUCTURE INPUT DATA
Structure ID = 00
Structure Type = Orifice-Circular
------------------------------------
# of Openings = 1
Invert Elev. = 395.83 ft
Diameter = 1.0000 ft
Orifice Coeff. _ .600
Structure ID
Structure Type
--------------
# of Openings
Crest Elev.
Weir Length
Weir Coeff.
WO
Weir-Rectangular
----------------
1
402.50 ft
6.72 ft
3.300000
Weir TW effects (Use adjustment equation)
SIN: Bentley Systems, Inc.
Bentley PondPack (10.00.027.00) 3:02 PM 9/13/2011
Type.... Outlet Input Data
Name.... Outlet 2
Page 2.03
File.... K:\10\10-0370\100371-Water Garden\H-H\PondPack Models\WGV.ppw
OUTLET STRUCTURE INPUT DATA
Structure ID = CO
Structure Type = Culvert-Circular
---------------
-----------------
No. Barrels ----
= 1
Barrel Diameter = 2.0000 ft
Upstream Invert = 395.73 ft
Dnstream Invert = 389.00 ft
Horiz. Length = 25.00 ft
Barrel Length = 25.89 ft
Barrel Slope = .26920 ft/ft
OUTLET CONTROL DATA...
Mannings n = .0130
Ke = .5000
Kb = .012411
Kr = .5000
HW Convergence = .001
(forward entrance loss)
(per ft of full flow)
(reverse entrance loss)
+/- ft
INLET CONTROL DATA...
Equation form = 1
Inlet Control K = .0098
Inlet Control M = 2.0000
Inlet Control c = .03980
Inlet Control Y = .6700
T1 ratio (HW/D) _ .000
T2 ratio (HW/D) = 1.172
Slope Factor = -.500
Use unsubmerged inlet control Form 1 equ. below T1 elev.
Use submerged inlet control Form 1 equ. above T2 elev.
In transition zone between unsubmerged and submerged inlet control,
interpolate between flows at Tl & T2...
At T1 Elev = 395.73 ft ---> Flow = 15.55 cfs
At T2 Elev = 398.07 ft ---> Flow = 17.77 cfs
Structure ID = TW
Structure Type = TW SETUP, DS Channel
------------------------------------
FREE OUTFALL CONDITIONS SPECIFIED
CONVERGENCE TOLERANCES ...
Maxi mum Iterations= 40
Min. TW tolerance = .01 ft
Max. TW tolerance = .01 ft
Min. HW tolerance = .01 ft
Max. HW tolerance = .01 ft
Min. Q tolerance = .00 cfs
Max. Q tolerance = .00 cfs
S/N:
Bentley PondPack (10.00.027.00)
3:02 PM
Bentley Systems, Inc.
9/13/2011
Type.... Composite Rating Curve
Name.... Outlet 2
Page 2.04
File.... K:\10\10-0370\100371-Water Garden\H-H\PondPack Models\WGV.ppw
***** COMPOSITE OUTFLOW SUMMARY ****
WS Elev, Total Q
----------------
Elev. Q
ft cfs
395.83
396.08
396.33
396.58
396.83
397.08
397.33
397.58
397.83
398.08
398.33
398.58
398.83
399.08
399.33
399.58
399.83
400.08
400.33
400.58
400.83
401.08
401.33
401.58
401.83
402.08
402.33
402.50
402.58
402.83
403.08
403.33
403.58
403.83
404.08
404.33
404.58
404.83
.00
.20
.68
1.32
2.14
2. 62
3.07
3.47
3.85
4.20
4.53
4.84
5.14
5.43
5.70
5.97
6.22
6.47
6.71
6. 94
7.16
7.39
7.61
7.81
8.01
8.21
8.41
8.54
9.05
12.65
17.97
24.43
31.24
37.92
40.19
41.63
42.78
43.76
Notes
-------- Converge ------------------
Tint Rl- 7----
ft +/-ft
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Contributing Structures
(no Q: OO,WO,CO)
OO,CO (no Q: WO)
OO,CO (no Q: WO)
OO,CO (no Q: WO)
OO,CO (no Q: WO)
OO,CO (no Q: WO)
OO,CO (no Q: WO)
OO,CO (no Q: WO)
OO,CO (no Q: WO)
OO,CO (no Q: WO)
OO,CO (no Q: WO)
OO,CO (no Q: WO)
OO,CO (no Q: WO)
OO,CO (no Q: WO)
OO,CO (no Q: WO)
OO,CO (no Q: WO)
OO,CO (no Q: WO)
OO,CO (no Q: WO)
OO,CO (no Q: WO)
OO,CO (no Q: WO)
OO,CO (no Q: WO)
OO,CO (no Q: WO)
OO,CO (no Q: WO)
OO,CO (no Q: WO)
OO,CO (no Q: WO)
OO,CO (no Q: WO)
OO,CO (no Q: WO)
OO,CO (no Q: WO)
OO,WO,CO
OO,WO,CO
OO,WO,CO
00,w0,C0
OO,WO,CO
OO,WO,CO
OO,WO,CO
OO,WO,CO
OO,WO,CO
OO1WO,CO
SIN: Bentley Systems, Inc.
Bentley PondPack (10.00.027.00) 3:02 PM 9/13/2011
Type.... Composite Rating Curve
Name.... Outlet 2
Page 2.05
File.... K:\10\10-0370\100371-Water Garden\H-H\PondPack Models\WGV.ppw
***** COMPOSITE OUTFLOW SUMMARY ****
WS Elev, Total Q Notes
---------------- -------- Converge --------------------
Elev. Q TW Elev Error
ft cfs ft +/-ft Contributing Structures
-------- ------- -------- ----- --------------------------
405.03 44.47 Free Outfall 00,W0,C0
SIN: Bentley Systems, Inc.
Bentley PondPack (10.00.027.00) 3:02 PM 9/13/2011
Appendix A
Index of Starting Page Numbers for ID Names
----- 0 -----
Outlet 2... 2.01, 2.04
----- W -----
Watershed... 1.01
A-1
SIN: Bentley Systems, Inc.
Bentley PondPack (10.00.027.00) 3:02 PM 9/13/2011
Water Garden Village
Stormwater Management Report
Raleigh, North Carolina
NITROGEN LOADING
CALCULATIONS
Water Garden Village W&R Project 0210371.00
Stormwater Management Report September 13, 2011
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Nitrogen Calculations for Expansion
to Exisiting Development
Project: Water Garden Apt Only
9/13/11
Total lot Acreage = 5.08 Ac.
Existing Impervious = 0.13 Ac.
Addtional (new) impervious = 2.28 Ac.
Total impervious = 2.41 Ac.
Existing managed open space = 4.95
New remaining open space (pervious) = 2.67 Ac.
Allocated open space = 2.53 Ac.
"New Nitrogen Loading"
Addtional (new) impervious @ 21.2 lb/acre = 48.34 lb
Allocated open space @ 1.2lb/acre = 3.03 lb
Total nitrogen contribution = 51.37 lb
Total nitrogen contribution per acre = 10.69 lb/acre
Amount nitrogen remaining to achieve 3.6 lb/acre = 7.09 lb/acre
,.new area" (near imp + new allocated open Epace) = 4.81 Ac.
Actual pounds to be removed by treatment= 34.07 lb <---(Amount nitrogen remaining after buydown' "new area")
Treatment device = LS-VFS
Efficiency of device to be used = 30.00 %
Impervious Area Treated = 2.33 Ac.
Open Space Treated = 1.46 Ac.
Reduction from BMP = 3.19 Ibs/ac
Net BMP Loading ater BMP 7.50 Ibs/ac
Offset Amount for buy Down 3.90 Ibs/ac
Buy Down Amount 3.90 Ibs/ac
x 4.81 ac
x $28.35 /lb/yr
x 30 years
Buy Down Amount = $15,922.43
Water Garden Village
Stormwater Management Report
Raleigh, North Carolina
LEVEL SPREADER-VEGETATIVE FILTER STRIP
CALCULATIONS
Water Garden Village W&R Project 0210371.00
Stormwater Management Report September 13, 2011
Red triangles at the upper right hand corner indicate design comments
Please complete the yellow shaded items.
O?QF WATF9oG
A
HCDEHR
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
401 CERTIFICATION APPLICATION FORM
LEVEL SPREADER - VEGETATED FILTER STRIP (LS-VFS) SUPPLEMENT
This form must be completely filled out, printed, initialed, and submitted.
I. PROJECT INFORMATION
Project name Water Garden Village
Contact name Ken jesneck, PE
Phone number 919469-3340
Date September 13, 2011
Drainage area number Site
II. DESIGN INFORMATION
The purpose of the LS-VFS Pollutant removal: 40% TSS, 30% TN, 35% TP
Stormwater enters LS-VFS from The drainage area
Type of VFS Engineered filter strip (graded & sodded, slope < 8%)
Explanation of any "Other" responses above
If Stormwater Enters the LS-VFS from the Drainage Area
Drainage area
Impervious surface area
Percent impervious
Rational C coefficient
Peak flow from the 1 in/hr storm
Time of concentration
Rainfall intensity, 10-yr storm
Peak flow from the 10-yr storm
Design storm
Maximum amount of flow directed to the LS-VFS
Is a flow bypass system going to be used?
166,835 ftz
106,286 ftz
63.71 %
n7.1
2.80 cfs
5.00 min
7.08 in/hr
19.79 cfs
1 inchihour storm
2.8 cfs
Y (Y or N)
Explanation of any "Other" responses above
If Stormwater Enters the LS-VFS from a BMP
Type of BMP
Peak discharge from the BMP during the design storm
Peak discharge from the BMP during the 10-year storm
Maximum capacity of a 100-foot long LS-VFS
Peak flow directed to the LS-VFS
Is a flow bypass system going to be used?
Pick one
Do not complete this section of the form.
Explanation of any "Other" responses above
cfs
cfs Do not complete this section of the form.
10 cfs
cfs Do not complete this section of the form.
(Y or N)
Underground Detention System
LS-VFS Design
Forebay surface area 220
Depth of forebay at stormwater entry point 24
Depth of forebay at stormwater exit point 12
sq ft Forebay is adequately sized.
in Depth is appropriate.
in Depth is appropriate.
Form SW401 - LS-VFS - 29Nov2010 - Rev.8 page 1 of 2
Feet of level lip needed per cfs
Computed minimum length of the level lip needed
Length of level lip provided
Width of VFS
Elevation at downslope base of level lip
Elevation at the end of the VFS that is farthest from the LS
Slope (from level lip to the end of the VFS)
Are any draws present in the VFS?
Is there a collector swale at the end of the VFS?
Bypass System Design (if applicable)
Is a bypass system provided?
Is there an engineered flow splitting device?
Dimensions of the channel (see diagram below):
M
B
W
y (flow depth for 10-year storm)
freeboard (during the 10-year storm)
Peak velocity in the channel during the 10-yr storm
Channel lining material
Does the bypass discharge through a wetland?
Does the channel enter the stream at an angle?
Explanation of any "Other' responses above
10 fvcfs
28 ft
30 ft
30 ft
391.25 fmsl
390.00 fmsl
4.17 %
N (Y or N)
N (Y or N)
Y (Y or N)
N (Y or N)
ft
ft
ft
ft
ft
fUsec
NICK one:
OK
N (Y or N)
Y (Y or N)
Form SW401 - LS-VFS - 29Nov2010 - Rev.8 page 2 of 2
Water Garden Village
Stormwater Management Report
Raleigh, North Carolina
HYDRAULIC GRADE LINE
ANALYSIS
Water Garden Village W&R Project 0210371.00
Stormwater Management Report September 13, 2011
O
N
A
? O
m O O
U N
v C14 r
m }
U
Uip r'
N
N
co
? r
m o ?
U m N
10
}
N
r N
(p O m
U ap U N N
? C
m -
co
O
d
r WO w h j
2
} rn CO
?/ko
o W)
N
}
Y
O
N O
N
co
? U
N
cn
Cl)
N
N
N
N
a
O
E
N
O
U.
U.
U
O
CL`
0
0
c
x
w
3
w
E
0
N
3
0
m
x
li
£a
11
Z
jr
L
Ile-41
O O O O O O
< V V < m M

O SL'Ol4 13 'AUI
9Z,£l4 13 wla
-
U
l - 9610+£ elS
l
UI £L'Ol4'13 'AUl I l c?
O 0096£ *13 'AUI
0££1413 WRi
Ul - 00'04+Z elS

N
Jpp
O
O

A 9416£ '13 'AUI
0016C'13 'AUI
'
'
W
L6£
OO
13
21
Jl - 00'94+0 elS
A SZ 06£ 13 AUI
9199£ 13 TWO
O - 00'00+0 elS
°o 00 °o oo °a
ri of ai C6 vi ai
v v °v cn on,
LiJ
LO
N
M
0
O
Lo
n
N
LO
N
in
N
N
O
O
N
P
r ?
v
L
V
l0
N
O
Y]
r
C4
N
O
O
N
r
0
N
J
N =
0
.y
C
d
W
N
3
d
N
E
O
3
0
m
v
T
2
E
N
E
O
co
N
O
CL`
4)
4-
O
L
a
L
4)
A
E
O
-'^0
cI
O 0 O 00 00 00

N O D vi I V
r ci
O ( 6
O

O

O
O
O
co
O

O
to

b U

l0
d

O

O
M
MO ZO'60ti '13 'Aul
Z£'Zlti "13 w!a
l o

4 :ul - 6ti"6L+0 eiS N
I I li t O
J

ul ELM? .13 '?ul
1n0 CV 96C '13 '^ul
LZ'Zlb 13 w21
0000+0 e1S
0

o° ,
CD t_n N O O

w
.y
c
m
x
w
m
3
d
E
0
3
0
T
e
_
b
O
O O
O O
O O
O 0 0
O
? O
O
N O) O Q
Q
O
N
in0 4Z"L04 l3
1.401,413 UM
4L ul 44"49+4 elc

inO 86'904'13'^ul
0011, u?
LO
£L ul
0

0
In

Zl ul

O
LO

O

inO 89504'13 '^ul

L I. O

t
o v
uI LO"404'13 '^ul
N
inO L6"404'13 '^ul fY

OL ul
0
UI Z4'404'13 '^ul N
inO
L071,117'13 WRf
6 ul

U1 8 N
inO 80

g :u
0

uI O6"E04 "13 '^ui
inO 08'£0

L :u
0
0

u I Z4
inO Z4"£04 '13"^ul

9:u J
2
u'>
u
in

v of C)

°
O
V a v a v m
W

l WL0413 "^ul

4 '13 W!21
- 6Z?8E+4 M TE

l99'904
'13 '^ul
O £ l'904 '13 '^ul
OZ'£l4'13 W21
- E£?£L+4 elS
o I
0
I
l 84"804'13
'^ul

4L?E14 "13 W21
l - E4"£9+£ e3S

4L'ZL4 "13 ui21
- 4L'09+Z e3S

Z4"404 '13 ?^ul

- LZ"LL+L e3S
a
L 404 '13 "nul
'404 '13 '^uI
LL'lL4'13 WRI
l - Z8'EZ+ I. e3S

4 "13 '^ul
44"LL4"13 W21
l - L919+0 e3S '
'E04'13 ?^ul

L9'll4'13 W!a
l - Z6'LE+O e3S
£L'£04'13 ?^ul
£0'L6£ '13"^ul
ZL' l l4 , 13 W!a

00'00+0 eLS

I u
0
u
v
u
u
0
I
O
C
O
'Yl
C
m
W
N
m
d
N
0
3
0
a
r
2
G
cN
C
O
N
0
CL`
W
O
a
L
3
CD
CO)
E
L
O
co
00 00 O 00 00 O
o
N ti v ac
O S ri
O
f a v v f f
o°

rn

0
0
'
'
' °
AUI
ln0 00
80ti
13 n
00"L H? "13 w21
LZ :ul - Z£19+0 e3S
0
co

o L
? v
m
d

0
f
0
cv)
O
N
O
J

uI 59'[04 '13 'AUI
3n0 09"£04'13 'Au1
44' L l4 '13 w!a
0000+0 ejS
0

o 0 0 o s o
CD
N o 0
? f f f f f
W
C
O
C
V
W
m
3
d
E
0
3
0
m
r
S

O
O 0
O C D 0 C
O O D
O
M
N O
r O
r _ r-
O M
O
f f f f f f
O
N
N
inO 05'604 '13 '^ul

LL ul

O
0
N

O
n

O
O

O _

t
U
l6
N
UI £8'804 '13 '^ul
in0 EL'804'13'^ul

9L :u r
O
n
uI OZ'80b'13 ^ul
in
'
'
'^u
O 5£
L04
13
l
LO

:u
9L
O
N J

ul
in0

0

r i a? v> ^ v
CD i
? V f f f V
W

bZ'
Elb '13 =6

- L6'0 L+Z EIS

40'Elb'13 w2i
1 - L8?66+0 e3S
0

6L'£L4'13 wRi

-
?
e
bb+O
l
OO
3S
a
E4'90b'13'^ul
£ L,904 '13 '^ul
OZ"£L4 '13 w!a
00'00+0 e3S

C
O
.y
C
d
W
W
d
d
O
N
3
0
C
R
L
2
O O O O O O
( 7
N ( D
? N
? n
O M
O
in0 09'014 '13 'nul v v v v v v
N
oZ u1 - £L'EZ+£ e3S
0
0

?n
n
N
U1 00'014
inO 9L'60 3 ' 0
N
6l•ul
Ln
N
N
O
O
N

r V

N

U1 9Z'604 '13 'Aul
inO 9Z'604 o

8l :u
N

O
O
r
LO
n
u1 9L'804
:
3

t,
:
In0 9EL0
3 Au
o

9l :u
J
10 =

UI N
In

0

M
a m 0 0
v v v v v
W
0T£l4'13 w!a

'13 'DUI
4 '1?ul
09?£l4 ?13 W!a

- 00'L4+Z e3S

'13 '?ul
9Z?£l4 "13 W!a
l - 00'£4+l e3S

s
e

'13 '?ui
'1
l
'
6L£14'13 w
!a
l - 00'44+0 e3S
£4'904'13 ??UI
£ L'904 '13 'DUI
OZ'El4'13 W!a
00"00+0 e3S
0
C
O
.N
C
m
W
m
3
m
`o
O
m
2
CD O O O O S
O
N f , <
r aD
O L 6
O
V V V V ? V
O

rn

o
co
'n
'
'
n °
ul
0 00
90b
i
13 n
00'1, 1,1?'13 Wla
LZ :ul - ZC19+0 PIS
0

O L
N V
l0
d
Ir
O

O
c li (n
O
N
?
J
2
W 991017 13 '^W
in0 09'£04 .13 'nul
441 H? .13 W1a
0000+0 PIS
0
$ o0 0
o
Y n _e .-
f
V
V V V
W
C
O
.N
C
d
W
d
d
E
0
3
0
c
m
v
S
O O O O O O
r
N C O I n N
'- W
O t D
O
I t
f
f
f
f
f
8

O
O
lnO 00'604 '13 'AUI
9Z* M? '13 W!b
ZZ :ul - 96'99+0 M
0

0
n
0

o L
? V
ld
N
Q'
0
10
f
0
M
0
N
O
J
2
X109'904 '13 'AUI
an0 Z4 404 'I3 '^UI
LO'ZL4'13 W!b
00'00+0 e1S
o

? ad ui N O t0
? f f f f f
W
C
O
C
m
Ti
W
d
3
d
N
E
O
N
3
0
q --
m
T
Water Garden Village
Stormwater Management Report
Raleigh, North Carolina
GUTTER SPREAD
CALCULATIONS
Water Garden Village W&R Project 0210371.00
Stormwater Management Report September 13, 2011
GUTTER FLOW SPREAD CALCULATIONS
PROJECT: Long Lake Pointe Piz: ww-?, ?tALI,
DATE: 7-Feb-04
LOCATION: CB 19 Marvino Lane
Design Criteria
1. SPREAD > '/2 TRAVEL LANE FOR A Q2 STORM EVENT Q2= 5.72 IN/HR
2. AT SAG, USE Q50 FOR STORM EVENT, I(Q50) = 9.0 IN/HR
3. AT SAG, INLET CAPACITY IS DOUBLED FOR DEBRIS BLOCKAGE.
4. GUTTER FLOW DEPTH < 5" FOR DESIGN FLOW
5. SPACING OF INLTS = 500' MAXIMUM
ROAD GEOMETRY
GUTTER SLOPE = 0.01 FT/FT
CROSS SLOPE = 0.0208 FT/FT
LANE WIDTH = 18 FEET
GUTTERWIDTH = 2 FEET
GUTTER FLOW
QMAX = (0.56 / N)(CROSS SLOPE)5/3 (GUTTER SLOPE) 1/2(SPREAD)8/3
MAXIMUM SPREAD
N=
FEET
FOR CONCRETE
CFS
IN/HR
QMAX - 4.06
I = 5.72
C = 0.59
AMAX - 1.20
AMAX = 52366
ACTUAL GUTTER FLOW
ACRES
SQ FT
AACTUAL = 28657 SQ FT
AACTUAL = 0.66 ACRES
AACTUAL 2.22
ACTUAL SPREAD = 8.77
GUTTER SPREAD OK
CFS
FEET
GUTTER FLOW SPREAD CALCULATIONS
PROJECT: Water Garden Village
DATE: 13-Sep-10 Revised
LOCATION: CB 19 Marvino Lane
Design Criteria
1. SPREAD > i/2 TRAVEL LANE FOR A Q2 STORM EVENT Q2= 5.72 IN/HR
2. AT SAG, USE Q50 FOR STORM EVENT, I(Q50) = 9.0 IN/HR
3. AT SAG, INLET CAPACITY IS DOUBLED FOR DEBRIS BLOCKAGE.
4. GUTTER FLOW DEPTH < 5" FOR DESIGN FLOW
5. SPACING OF INLTS = 500' MAXIMUM
ROAD GEOMETRY
GUTTER SLOPE = 0.01 FT/FT
CROSS SLOPE = 0.0208 FT/FT
LANE WIDTH = 18 FEET
GUTTERWIDTH = 2 FEET
GUTTER FLOW
QMAX = (0.56 / N)(CROSS SLOPE)5/3 (GUTTER SLOPE) 1/2(SPREAD)8/3
MAXIMUM SPREAD =
N=
AMAX -
I=
C=
AMAX
AMAX
11
0.013
4.06
5.72
0.65
1.09
47516
ACTUAL GUTTER FLOW
ACTUALSPREADGUTTER SPREAD OK
AACTUAL - 23935
AACTUAL - 0:55
AACTUAL 2.04'
= 8.51
FEET
FOR CONCRETE
CFS
IN/HR
ACRES
SQ FT
SQ FT
ACRES
CFS
FEET
Water Garden Village
Stormwater Management Report
Raleigh, North Carolina
SEDIMENTATION BASIN
SKIMMER DESIGN
Water Garden Village W&R Project 0210371.00
Stormwater Management Report September 13, 2011

Project Name: Water Garden-SB 1
City/State: Raleigh, NC
Skimmer Design
Skimmer Size ring Volume 2,358 ft3
Draw Down Time 2-3 days
Dewatering Flow Rate (Qd)= 786 ft3/day
Skimmer Size:
Orifice Diameter (D)=
Dewatering Time (td)=
Skimmer
Size Head
1.5" 0.125 ft.
2" 0.167 ft.
2.5" 0.208 ft.
3" 0.25 ft.
4" 0.333 ft.
5" 0.333 ft.
6" 0.417 ft.
8" 0.5 ft.
2.0 0.167
0.91 in
2.50 days
USE 1 In DIAMETER ORIFICE
Actual Diameter = 0.005454 sq ft
Head = 0.17 ft
Flow = 0.01 cfs
Project #: 2100371
Date: _ 13-SPr-i i
Use 1 in

Project Name: Water Garden-SB 2
City/State: Raleigh, NC
Skimmer Design
Skimmer Size ring Volume 10,512 ft 3
Draw Down Time 2-3 days
Dewatering Flow Rate (Qd)= 3,504 ft3/day
Skimmer Size:
Orifice Diameter (D)=
Dewatering Time (td)=
Skimmer
Size Head
1.5" 0.125 ft.
2" 0.167 ft.
2.5" 0.208 ft.
3" 0.25 ft.
4" 0.333 ft.
5" 0.333 ft.
6" 0.417 ft.
8" 0.5 ft.
4.0 0.33
1.62 in
2.59 days
USE 1.5 In DIAMETER ORIFICE
Actual Diameter = 0.012272 sq ft
Head = 0.17 ft
Flow = 0.03 cfs
Project #: 2100371
Date: 13-Sep-1 1
Use 1.75 in