20061617 Ver 3_Stormwater Info_20080716

WITHERS ,° RAVENEL
ENGINEERS I PLANNERS I SURVEYORS
iii MacKenan Drive
CARY, NORTH CAROLINA, 27511
[phone]
FAX [phone]oo8
TO: North Carolina Division of Water Quality
2321 Crabtree Boulevard, Suite 250
Raleigh, North Carolina 276o7
WE ARE SENDING YOU
? Shop Drawings
? Copy of Letter
® Attached
® Prints
? Change order
L -FfER SFTRANSWRAL
DATE o7/15/o8 JOB NO. 020 0261.1
ATTENTION C n d i Ka ro l
PHONE# [phone]
RE: Wendell Falls Subdivision
Marck Creek {030402, 27-38, C, NSW}
SF1

? Under separate cover via
? Plans ? Samples
? Diskette ?
the following items:
? Specifications
COPIES DATE NO. DESCRIPTION
Stormwater Management Plans
S Supportinz Calculations and Documents
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:
JUL 1 5 2008
J NR -',N ER QUAiUI)"
El'l `T n gTMAWATER BRANCH
COPY TO: File SIGNED: Ken Jesneck, PE
? Resubmit
? Submit
? Return
- copies for approval
copies for distribution
corrected prints

if enclosures are not as noted, kindly notify us at once.
WITHERS RAVENEL
O to -Ito ? -L V 3
SF 15 PHASE 1
STORMWATER MANAGEMENT REPORT
DWQ #20061617
USACOE Action ID #2006-20100
Wendell Falls Subdivision
Wendell, North Carolina
Prepared For:
Wendell Falls Residential, LLC
566o Six Forks Road
Suite #202
Raleigh. NC 276o9
Attn: Mike )ones
Prepared By:
WITHERS & RAVENEL, INC
111 MacKenan Drive
Cary, North Carolina 27511
July 2008
W&R Project No. 205261.19
,JUL ?[R@fflowlgp
1 5 2008
DENR - WATER QUAUTY
WETLANDS AND STORMWATER BRANCH
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WENDELL FALLS SUBDIVISION
SF 15 PHASE 1
STORMWATER MANAGEMENT PLAN
WENDELL, NORTH CAROLINA
INTRODUCTION
The purpose of this SF 15 Phase 1 Stormwater Management Report is to document the design of the
grassed Swale and wet detention pond for a storm water outlet from the future development of SF
15 of Wendell Falls Subdivision. SF 15 is located to the north of Poole Road approximately 1000
feet from the Lake Myra bridge crossing. SF 15 is comprised of two phases, of which only Phase 1
has been designed. The purpose of Phase 1 is to provide a public street access to the Lake Myra
Elementary School that is currently under construction. Phase 1 includes 21 single family
residences, with 105 single family residences proposed for Phase 2. Phase 2 is currently under
design, but the grassed swale and wet detention pond has been designed for full build out. The
primary purpose of the grassed Swale and the wet detention is to capture and treat the runoff from
the first inch of precipitation. As a result of the design, a secondary benefit is the attenuation of the
post-development stormwater runoff rates for the 1-year, 10-year, and 100-year storm events.
METHODOLOGY
The stormwater study was conducted using the natural drainage features as depicted by 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 1-year, 10-year, 50-year, and 100-year rainfall events for the Wendell
area
? Formulation of the 1-year, 10-year, 50-year, and 100-year flood hydrographs for the pre-
and post-development drainage areas
Hydraulic
? Routing the 1-year, 10-year, 50-year, and 100-year flood hydrographs for pre-
development runoff from the site.
? Routing the 1-year, 10-year, 50-year, and 100-year flood hydrographs for post-
development runoff through the proposed wet pond.
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
impoundment. The rainfall/runoff hydrographs, stage-storage and stage-discharge functions have
been compiled to create a routing computer simulation model using Haestad Methods PondPack
v10.0 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 10-year, 50-
year and 100-year storm events. This method requires three basic parameters: a curve number (CN),
time of concentration (tc), and drainage area.
Curve numbers were based on soil type and land use. Soil types were delineated from the Soil
Wendell Falls Subdivision i W&R Project 20526i.ig
SF 15 Phase i Stormwater Management Report July 2oo8
WENDELL FALLS SUBDIVISION
SF i5 PHASE i
STORMWATER MANAGEMENT PLAN
WENDELL, NORTH CAROLINA
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. Post
development land use is based on the proposed site plan. The curve numbers selected for the
impervious and pervious areas are 98 and 73 respectively, for a composite curve number of 89.5,
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 area based on the flow time through the piped drainage systems and small
areas of sheet flow. Due to length of pipe, a time of concentration of 5 minutes (0.0833 hours) has
been selected for the network.
HYDRAULICS
Computer simulated reservoir routing of the 1-year, 10-year, and 100-year design storms utilized
stage-storage and stage-discharge functions. Stage-storage functions were derived from the proposed
grading of the wet pond. A non-linear regression relation for surface area versus elevation was
derived for the basin. This relation estimates the incremental volume of the basin to the stage or
elevation of the basin. Stage-discharge functions were developed to size the proposed outlet
structure.
CONCLUSIONS
Based on the routing study, the proposed constructed wetland ponds have sufficient volume to
safely pass the 100-year storm. The outlet was designed to discharge the first inch of runoff through
a separate outlet barrel. Larger storm events bypass the level spreader.
Wendell Falls Subdivision 2 W&R Project 205261.19
SF 15 Phase 1 Stormwater Management Report July 2008
WENDELL FALLS SUBDIVISION
SF 15 PHASE i
STORMWATER MANAGEMENT PLAN
WENDELL, NORTH CAROLINA
STORMWATER MANAGEMENT SYSTEM DESIGN SUMMARY
PROPOSED WET DETENTION POND
• Water Quality Volume = 66,850 CF
• Sediment Storage = 16,710 CF
• 10'x10' Riser Crest = 211.35
• 4" diameter drawdown orifice @ 209.50
• 54" diameter RCP outlet barrel
• Top of dam = 213.50

Storm Event Peak Water
Surface
Elevation
Freeboard
Qpeak Outflow
1" Storm 211.35 2.15 ft 0.38 cfs
1-Year 211.93 1.57 ft 57.2 cfs
10-Year 212.48 1.02 ft 150 cfs
100-Year 212.93 0.57 ft 198 cfs
ATTENUATION RESULTS

Storm Event Pre-
Development
Flows (cfs) Post-
Development
Flows (cfs)
Qpeak Outflow
1" Storm NA NA 0.38 cfs
1-Year 60.3 88.7 57.2 cfs
10-Year 138 165 150 cfs
100-Year 207 224 198 cfs
PROPOSED GRASSED SWALE
• Side Slopes = 5:1 (H:V)
• Longitudinal Slope = 0.005 ft/ft
• Bottom Width = 27 ft
• Velocity for 10-yr 24-Hr Storm = 0.97 ft/s
• Velocity for 10-yr Peak Storm = 3.38 ft/s
PROPOSED LEVEL SPREADER
• Length = 25 ft
Wendell Falls Subdivision 3 W&R Project 20526i.ig
SF 15 Phase i Stormwater Management Report July 2oo8
WET DETENTION
POND/SITE OUTFLOW
CALCULATIONS
AND
WORKSHEETS
Wendell Falls Subdivision W&R Project 205261.ig
SF 15 Phase i Stormwater Management Report July 2008
Permit
(to be provided by DWQ)
111111. RE 01,010 tTEW CHEF
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.
Page/ Plan
In' ials Sheet yo.
01
G' 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),
- Basin dimensions,
- Pretreatment system,
- High flow bypass system,
Maintenance access,
Proposed drainage easement and public right of way (ROW),
Overflow device, and
- Boundaries of drainage easement.
?) 2. Partial plan (1" = 30' or larger) and details for the wet detention basin showing:
ZZ77 Outlet structure with trash rack or similar,
- Maintenance access,
- Permanent pool dimensions,
- Forebay and main pond with hardened emergency spillway,
Basin cross-section,
- Vegetation specification for planting shelf, and
- Filter strip.
e , - "
'
3. Section view of the dry detention basin (1
= 20
or larger) showing:
- Side slopes, 3:1 or lower,
- Pretreatment and treatment areas, and
- Inlet and outlet structures.
(u A 4. If the basin is used for sediment and erosion control during construction, clean out of the basin is specified
sIEC
(?,1 on the plans prior to use as a wet detention basin.
5. A table of elevations, areas, incremental volumes & accumulated volumes for overall pond and for forebay,
to verify volume
rovided
p
.
W 6. A construction sequence that shows how the wet detention basin will be protected from sediment until the
entire drainage area is stabilized.
?? 7. The supporting calculations.
n
L 8. A copy of the signed and notarized operation and maintenance (0&M) agreement.
-+? 9. A copy of the deed restrictions (if required).

(Nt 10. A soils report that is based upon an actual field investigation, soil borings, and infiltration tests. County
soil maps are not an acceptable source of soils information.
L,?OL
Form SW401-Wet Detention Basin-Rev.4 Part III. Required Items Checklist, Page 1 of 1
Permit No.
NCDENR
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
401 CERTIFICATION APPLICATION FORM
WET DETENTION BASIN SUPPLEMENT
This form must be filled out, printed and submitted.
The Required Items Checklist (Part lll) must be printed, filled out and submitted along with all of the required information.
(to be provided by DWQ)
O?1OE?W A rt,
O Niii? r
1. PROJECT INFORMATION
Project name Wendell Falls, SF 15 Phase 1
Contact person Ken Jesneck, PE
Phone number 919-469-3340
Date 6-Jun-08
Drainage area number BMP 15.1
II. DESIGN INFORMATION
Site Characteristics
Drainage area 47.60 ft
Impervious area 17.82 ftz
% impervious 37.44 %
Design rainfall depth 1.00 in
Storage Volume: Non-SR Waters
Minimum volume required 66,847.00 ft3
Volume provided 67,000.00 -ft'
Storage Volume: SR Waters
1-yr, 24-hr runoff depth in
Pre-development 1-yr, 24-hr runoff ft3
Post-development 1-yr, 24-hr runoff ft3
Minimum volume required ft3
Volume provided ft3
Peak Flow Calculations
1-yr, 24-hr rainfall depth 3.60 in
Rational C, pre-development 0.25 (unitless)
Rational C, post-development 0.65 (unitless)
Rainfall intensity: 1-yr, 24-hr storm 0.22 in/hr
Pre-development 1-yr, 24-hr peak flow 60.30 ft3/sec
Post-development 1-yr, 24-hr peak flow 88.72 ft3/sec
Pre/Post 1-yr, 24-hr peak flow control 28.42 ft3/sec
Basin Elevations
Basin bottom elevation 204.00 It
Sediment cleanout elevation 205.00 It
Bottom of shelf elevation 209.00 It
Permanent pool elevation 209.50 ft
SHWT elevation 200.00 ft
Top of shelf elevation 210.00 ft
Temporary pool elevation 211.35 It
Form SW401-Wet Detention Basin-Rev.4 Parts I. & II. Design Summary, Page 1 of 2
Permit
(to be provided by DWO)
11. DESIGN INFORMATION
Volume and Surface Area Calculations
SAIDA ratio 1.35 (unitless)
Surface area at the bottom of shelf 29,688.00 ftz
Volume at the bottom of shelf 118,379.00 ft3
Permanent pool, surface area required 30,977.00 ftz
Permanent pool, surface area provided 33,658.00 ftz OK
Permanent pool volume 134,204.00 ft3
Average depth for SA/DA tables 3.99 ft OK
Surface area at the top of shelf 37,737.00 ft2
Volume at the top of shelf 134,852.00 ft3
Forebay volume 28,827.00 ft3
Forebay % of permanent pool volume 21.48 % OK
Temporary pool, surface area provided 42,727.00 ff
Drawdown Calculations
Treatment volume drawdown time 4.00 days OK
Treatment volume discharge rate 0.38 ft3/s
Pre-development 1-yr, 24-hr discharge 60.30 ft3/s OK
Post-development 1-yr, 24-hr discharge 57.22 ft3/s OK
Additional Information
Diameter of orifice 4 in
Design TSS removal 85 %
Basin side slopes 3.00 :1 OK
Vegetated shelf slope 10.00 :1 OK
Vegetated shelf width 10.00 ft OK
Length of flowpath to width ratio 4.00 :1 OK
Length to width ratio 4.00 :1 OK
Trash rack for overflow & orifice? Y (Y or N) OK
Freeboard provided 1.00 ft OK
Vegetated filter provided? Y (Y or N) OK
Recorded drainage easement provided? Y (Y or N) OK
Capures all runoff at ultimate build-out? Y (Y or N) OK
Drain mechanism for maintenance or emergencies Y
Form SW401-Wet Detention Basin-Rev.4 Parts 1. & 11. Design Summary, Page 2 of 2
Job File: K:\05\05-260\05261.19-Wendell Falls - SF 15 Phase- 1\H-H\BMP15.1 WET POND.PPW
Rain Dir: K:A05\05-260\05261.19-Wendell Falls - SF 15 Phase 1\H-H\
--------------------------
JOB TITLE
--------------------------
Project Date: 6/6/2008
Project Engineer: Ken Jesneck
Project Title: Wendell Falls SF 15 Phase 1
Project Comments:
This report summarizes the design and analysis of the wet
detention pond for SF 15 Phases 1 and 2.
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Table of Contents
i
Table of Contents
********************** MASTER SUMMARY *******+**************
Watershed....... Master Network Summary ............. 1.01
*************** NETWORK SUMMARIES (DETAILED) ***************
Watershed....... 1
Executive Summary (Nodes) .......... 2.01
Executive Summary (Links) .......... 2.02
Watershed....... 10
Executive Summary (Nodes) .......... 2.03
Executive Summary (Links) .......... 2.04
Watershed....... 100
Executive Summary (Nodes) .......... 2.05
Executive Summary (Links) .......... 2.06
:t*a*-********++******+* TO CALCULATIONS *'+*+*+****+*********
PRE ............. Tc Calcs ........................... 3.01
SF 15 PHS 1&2 ... To Calcs ........................... 3.03
*******************+** CN CALCULATIONS *******+*+**++*******
PRE ............. Runoff CN-Area ..................... 4.01
SF 15 PHS 1&2... Runoff CN-Area ..................... 4.02
******************** RUNOFF HYDROGRAPHS ********************
PRE ............. 1
Unit Hyd. Summary .................. 5.01
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Table of Contents
Table of Contents (continued)
Unit Hyd. (HYG output) ........ 5.02
PRE ............. 10
Unit Hyd. Summary
Unit Hyd. (HYG output) ............. 5.05
PRE ............. 100
Unit Hyd. Summary .................. 5.07
Unit Hyd. (HYG output) ............. 5.08
SF 15 PHS 1&2... 1
Unit Hyd. Summary .................. 5.10
Unit Hyd. (HYG output) ............. 5.17.
SF 15 PHS 1&2... 10
Unit Hyd. Summary .................. 5.13
Unit Hyd. (HYG output) ............. 5.19
SF 15 PHS 1&2... 100
Unit Hyd. Summary .................. 5.17
Unit Hyd. (HYG output) ............. 5.18
++****+*********a+**** POND VOLUMES r********++?**+*******
POND 10......... Vol: Elev-Area ..................... 6.01
* ****************** OUTLET STRUCTURES *********************
Outlet 1........ Outlet Input Data .................. i_01
Individual Outlet Curves ........... 7.05
Composite Rating Curve ............. 7.09
ii
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Type.... Master Network Summary Page 1.01
Name.... Watershed
File.... K:A05\05-260\05261.19-Wendell Fa1J_s - SF 15 Phase 1\H-H\RmP15.1 Wet Pond.ppw
MASTER DESIGN STORM SUMMARY
Network Storm Collection: RDU NOAA 14 Desi
Total
Depth
Return Event in
10 4.9800
25 5.9000
50 6.6300
100 7.3700
1 3.0000
Rainfall
Type
----------------
Time-Depth Curve
Time-Depth Cur-,.,e
Time-Depth Curve
Time-Depth Curve
Synthetic Curve
RNF ID
RDU NOAA l0yr
RDU NOAA 25yr
RDU NOAA 50yr
RDU HOAA 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)
Return HYG Vol Qpeak
Node ID Type Event ac-ft Trun hrs
-----
*OUT --------
10 ---- ----
JCT ------
10 ---------- --
13.615 ---------
12.3000
*OUT 10 JCT 25 17.048 12.3000
*OUT 10 JCT 50 19.808 12.3000
*OUT 10 JCT 100 22.629 12.3000
*OUT 10 JCT 1 6.539 12.2000
*OUT 20 JCT 10 10.337 12.2000
*OUT 20 JCT 25 13.453 12.2000
*OUT 20 JCT 50 16.004 12.2000
*OUT 20 JCT 100 18.641 12.2000
*OUT 20 JCT 1 4.249 12.0500
Max
Qpeak Max WSEL Pond Storage
cfs ft ac-ft
-------- -------- ------------
149.67
169.67
184.07
197.87
57.22
137.91
166.84
187.20
206.51
60.30
POND 10 IN POND 10 13.679 12.2000 164.25
POND 10 IN POND 25 17.114 12.2000 189.80
POND 10 IN POND 50 19.876 12.2000 207.82
POND 10 IN POND 100 22.698 12.2000 224.59
POND 10 IN POND 1 6.594 12.0500 88.72
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Type.... Master Network Summary Page 1.02
Name.... Watershed
File.... K:A05\05-260\05261.1.9-Wendell Falls - SF 15 Phase 1\H-H\BMP15.1 Wet Pernd.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 Pcnd Storage
Node
------ ID
-----
------ Type
---- Event
------ ac-ft Trun
---------- -- hrs
---
----- cfs
-
- ft ac-ft

POND
10
OUT
POND
10
13.615 -
12.3000 -
-
----
149.67 --------
212.48 ------------
3.034
POND 10 OUT POND 25 17.048 12.3000 169.67 212.66 3.250
POND 10 OUT POND 50 19.808 12.3000 184.07 212.80 3.421
POND 10 OUT POND 100 22.629 12.3000 197.87 212.93 3.587
POND 10 OUT POND 1 6.539 12.2000 57.22 211.93 2.387
PRE AREA 10 10.337 12.2000 137.91
PRE AREA 25 13.453 12.2000 166.84
PRE AREA 50 16.004 12.2000 187.20
PRE AREA 100 18.641 12.2000 206.51
PRE AREA 1 4.249 12.0500 60.30
SF 15 PHS 1&2 AREA 10 13.679 12.2000 164.25
SF 15 PHS 1&2 AREA 25 17.114 12.2000 189.80
SF 15 PHS 1&2 AREA 50 19.8"76 12.2000 207.82
SF 15 PHS 1&2 AREA 100 22.698 12.2000 224.59
SF 15 PHS 1&2 AREA 1 6.594 12.0500 88.72
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Type.... Executive Summary (Nodes) Page 2.01
Name.... Watershed Event: 1 yr
File.... K:\05\05-260\05261.19-Wendell Falls - SF 15 Phase 1\H-H\BMP15.1 Wet Pond.ppw
Storm... TypeII 24hr Tag: 1
NETWORK SUMMARY -- NODES
(Trun.- HYG Truncation: Blank-None; L=Left; R=Rt; LR=Left & Rt)
DEFAULT Design Storm File,ID RDU HOAA 14 Desi
Storm Tag Name = 1
Data Type, File, ID
Storm Frequency
Total Rainfall Depth
Duration Multiplier
Resulting Duration
Resulting Start Time
Synthetic Storm TypeII 24hr
1 yr
3.0000 in
1
24.0000 hrs
.0000 hrs Step= .1000 hrs End- 24.0000 hrs
HYG Vol Qpeak Qpeak Max WSEL
Node ID Type ac-ft Trun. hrs cfs ft
-----------------
Outfall OUT 10 ----
JCT ---------
6.539 - -- ---------
12.2000 -------- ---------
57.22
Outfall OUT 20 JCT 4.249 12.0500 60.30
POND 10 IN POND 6.594 12.0500 88.72
POND 10 OUT POND 6.539 12.2000 57.22 211.93
PRE AREA 4.249 12.0500 60.30
SF 15 PHS 1&2 AREA 6.594 12.0500 88.72
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Type.... Executive Summary (Links) Page 2.02
Name.... Watershed Event: 1 yr
File.... 1<,:A05\05-260\05261.19-Wendell Falls - SF 15 Phase 1\H-H1\BMP15.1 Wet Pond.ppw
Storm... TypeII 24hr Tag: 1
NETWORK SUMMARY -- LINKS
(UN=Upstream Node; DL=DNstream End of Link; DN=DNstream Node)
(Trun.= HYG Truncation: Blank=None; L=Left; R=Rt; LR=Left & Rt)
DEFAULT Design Storm File,ID = RDU NOAA 14 Desi
Storm Tag Name - 1
Data Type, File, ID - Synthetic Storm TypeII
----------------------------------------------
Storm Frequency - 1 yr
Total Rainfall Depth= 3.0000 in
Duration Multiplier = 1
Resulting Duration - 24.0000 hrs
Resulting Start Time= .0000 hrs Step- .1000 hrs
HYG Vol Peak Time
Link ID Type ac-ft Trun. hrs
---------------- ---- ----------- --- -------
ADDLINK 10 ADD UN 6.594 12.0500
DL 6.594 12.0500
DN 6.594 12.0500
ADDLINK 20 ADD UN 4.249 12.0500
DL 4.249 12.0500
DN 4.249 12.0500
ROUTE 10 PONDrt UN 6.594 12.0500
ROUTE 10 6.539 12.2000
DL 6.539 12.2000
DN 6.539 12.2000
-------------------
24hr
End= 24.0000 hrs
Peak Q
cfs End Points
------ ----------------
88.72 SF 15 PHS 1&2
88.72
88.72 POND 10 IN
60.30 PRE
60.30
60.30 OUT 20
88.72 POND 10 IN
57.22 POND 10 OUT
57.22
57.22 OUT 10
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Type.... Executive Summary (Nodes) Page 2.03
Name.... Watershed Event: 10 yr
File.... K:A05\05-260\05261.19-Wendell Falls - F 15 Phase 1\H-H\BMP15.1 Wet Pond.ppw
Storm.._ RDU NOAA 10yr Tag: 10
NETWORK SUMMARY -- NODES
(Trun.= HYG Truncation: Blank=None; L=Left; R=Rt; LR=Left & Rt)
DEFAULT Design Storm File,ID = RDU NOVA 14 Desi
Storm Tag Name = 10
Data Type, File, ID = Time-Depth Curve RDU NOAA 10;Yr
Storm Frequency - 10 yr
Total Rainfall Depth = 4.9800 in
Duration Multiplier = 1
Resulting Duration = 23.9904 firs
Resulting Start Time = .0000 h rs Step= .0833 hrs End= 23.9904 hrs
HYG Vol Qpeak Qpeak Max WSEL
Node ID Type ac-ft Tr un. hrs cfs ft
-----------------
Outfall OUT 10 ---- --
JCT --------- -
13.615 -- ---------
12.3000 -------- ---------
149.67
Outfall OUT 20 JCT 10.337 12.2000 137.91
POND 10 IN POND 13.679 12.2000 164.25
POND 10 OUT POND 13.615 12.3000 149.67 212.48
PRE AREA 10.337 12.2000 137.91
SF 15 PHS 1&2 AREA 13.679 12.2000 164.25
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Type.... Executive Summary (Links) Page 2.04
Name.... Watershed Event: 10 yr
File.... K:\05\05-260\05261.19-Wendell Falls - SF 15 Phase 1\H-H\HMP15.1 Wet Pond.pp,,,
Storm... RDU NOAA 10yr Tag: 10
NETWORK SUMMARY -- LINKS
(UN=Upstream Node; DL=DNstream End of Link; DN=DNstream Node)
(Trun.= HYG Truncation: Blank=None; L=Left; R=Rt; LR=Left & Rt)
DEFAULT Design Storm File,ID = RDU NOAH 14 Desi
Storm Tag Name = 10
----------
Data Type, ---------
File, ID ---
= ----------------
Time-Depth Curve -----------------
RDU NOAH 10yr -------------
Storm Freq uency = 10 yr
Total Rain fall Dept h= 4.9800 in
Duration M ultiplier = 1
Resulting Duration = 23.9904 hrs
Resulting Start Tim e= .0000 hrs Step= .0833 hrs End= 23.9904 hrs
HYG Vol Peak Time Peak Q
Link ID
---------------- Type
- ---- ac-ft Trun.
-- hrs cfs End Points

ADDLINF 10
ADD
UN --------- ---
13.679 ----- -- --
12.2000 ------
164.25 ----------------
SF 15 PHS 1&2
DL 13.679 12.2000 164.25
DN 13.679 12.2000 164.25 POND 10 IN
P.DDLINK 20 ADD UN 10.337 12.2000 13'7.91 PRE
DL 10.337 12.2000 137.91
DN 10.337 12.2000 137.91 OUT 20
ROUTE 10 PONDrt UN 13.679 12.2000 164.25 POND 10 IN
ROUTE 10 13.615 12.3000 149.67 POND 10 OUT
DL 13.615 12.3000 149.67
DN 13.615 12.3000 149.67 OUT 10
SIN:
Bentley PondPack (10.00.027.00)
9:47 AM
Bentley Systems, Inc.
7/2/2008
Type.... Executive Summary (Nodes) Page 2.05
Name.... Watershed Event: 100 yr
File.... K:A05\05-260\05261.19-Wendell Falls - SF 15 Phase 1\H-H\BMP15.1 Wet Pond.ppw
Storm... RDU NOAA. 100yr Tag: 100
NETWORK SUMMARY -- NODES
(True.- HYG Truncation: Blank-None; L=Left; R=Rt; LR=Left & Rt)
DEFAULT Design Storm File,ID - RDU NOAA 14 Desi
Storm Tag Name = 100
Data Type, File, ID = Time-De pth Curve RDU NOAA 100yr
Storm Frequency = 100 yr
Total Rainfall Depth = 7.3700 in
Duration Multiplier = 1
Resulting Duration = 23.9990 hrs
Resulting Start Time = .0000 h rs Step= .0833 hrs End= 23.9990 hrs
HYG Vol Qpeak Qpeak Max WSEL
Node ID Type ac-ft Tr un. hrs cfs ft
-----------------
Outfall OUT 10 ---- --
JCT -------- -
22.629 - ---------
12.3000 -------- ---------
197.87
Outfall OUT 20 JCT 18.641 12.2000 206.51
POND 10 IN POND 22.698 12.2000 224.59
POND 10 OUT POND 22.629 12.3000 197.87 212.93
PRE AREA 18.641 12.2000 206.51
SF 15 PHS 1&2 AREA 22.698 12.2000 224.59
S/N: Bentley Systems, Inc.
Bentley PondPack (10.00.027.00) 9:47 AM 7/2/2008
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Type.... Executive Summary (Links) Page 2.06
Name.... Watershed Event: 100 yr
File.... K:A05\05-260\05261.19-Wendell Falls - SF 15 Phase 1\H-H\BMP15.1 Wet Pond.ppw
Storm... RDU NOP.A 100yr Tag: 100
NETWORK SUMMARY -- LINKS
(UN=Upstream Node; DL=DNstream End of Link; DN=DNstream Node)
(Trun.= HYG Truncation: Blank=None; L=Left; P Rt; LR=Left & Rt)
DEFAULT Design Storm File,ID = RDU NOAA 14 Desi
Storm Tag Name = 100
Data Type, File, ID = Time-Depth Curve RDU N077A 100yr
Storm Frequency = 100 yr
Total Rainfall Depth= 7.3700 in
Duration Multiplier = 1
Resulting Duration = 23.9990 hrs
Resulting Start Time= .0000 hrs Step- .0833 hrs End= 23 .9990 hrs
HYG Vol Peak Time Peak Q
Link ID Type
---
------- ac-ft Trun. hrs cfs End Points
-
----- ----
ADDLINK 10 ADD UN -----------
22.698 --- ------- -
12.2000 -------
224.59 ----------------
SF 15 PHS 1&2
DL 22.698 12.2000 224.59
DN 22.698 12.2000 224.59 POND 10 IN
ADDLINK 20 ADD UN 18.641 12.2000 206.51 PRE
DL 18.641 12.2000 206.51
DN 18.641 12.2000 206.51 OUT 20
ROUTE 10 PONDrt UN 22.698 12.2000 224.59 POND 10 IN
ROUTE 10 22.629 12.3000 197.87 POND 10 OUT
DL 22.629 12.3000 197.87
DN 22.629 12.3000 197.87 OUT 10
SIN:
Bentley PondPack (10.00.027.00)
9:47 AM
Bentley Systems, Inc.
7/2/2008
Type.... Tc Calcs
Name.... PRE
Page 3.01
File.... K:`•,05\05-260\05261.19-Wendell Falls - SF 15 Fhase 1\H-H\BMP15.1 wet Pond.ppw
........................................................................
........................................................................
TIME OF CONCENTRATION CALCULATOR
Segment #1: Tc: User Defined
Segment #1 Time: .2500 hrs
------------------------------------------------------------------------
Total Tc: .2500 hrs
-------------------------
S/N: Bentley Systems, Inc.
Bentley PondPack (10.00.027.00) 9:47 AM 7/2/2008
Type.... Tc Calcs
Name.... PRE
Page 3.02
File.... K:A05\05-260\05261.19-Wendell Falls - SF 15 Phase 1\H-H\BMPI".1 Wet Pond -ppw
------------------------------------------------------------------------
Tc Equations used...
------------------------------------------------------------------------
=_--- User Defined ___________________ - - _______________________
Tc = value entered by user
Where: Tc = Time of concentration
SIN:
Bentley PondPack (10.00.027.00)
9:97 AM
Bentley Systems, Inc.
7/2/2008
Type.... Tc Calcs
Name.... SF 15 PHS 1&2
Page 3.03
File.... K.:A05\05-260\05261.19-Wendell Falls - SF 15 Phase 1\H-H\BMP15.1 Wet Pend.pp.J
........................................................................
TIME OF CONCENTRATION CALCULATOR
........................................................................
........................................................................
Segment #l: Tc: User Defined
Segment #1 Time: .1500 hrs
------------------------------------------------------------------------
---- ------------------
Total Tc: .1500 hrs
-------------------------
S/N:
Bentley PondPack (10.00.027.00)
9:47 AM
Bentley Systems, Inc.
7/2/2008
Type.... Tc Calcs
Name.... SF 15 PHS 1&2
Page 3.04
File.... K:A05\05-260\05261.19-Wendell Falls - SF 15, Phase I \1H-H\BMP15. I Wet Pond.ppw
-------------------------------------------------------------------------
Tc Equations used...
-------------------------------------------------------------------------
User Defined -----------------------------------------------------
Tc - value entered by user
Where: Tc = Time of concentration
SIN:
Bentley PondPack (10.00.027.00)
9:47 AM
Bentley Systems, Inc.
7/2/2008
Type.... Runoff CN-Area
Name.... PRE
Page 4.01
File.... K:A05\05-260\05261.19-Wendell Falls - SF 15 Phase 1\H-H\B1,JP15.1 Wet Pond.ppw
RUNOFF CURVE NUMBER DATA
..........................................................................
Impervious
Area Adjustment Adjusted
Soil/Surface Description CN
- ---- acres
--------- °C CUC
----- ----- CN
------
-------------------------------
Impervious Areas - Paved; curbs and 77 17.820 77.00
Open space (Lawns,parks etc.) - Fai 71 29.780 77.00
COMPOSITE AREA & WEIGHTED CN --->
........................................ 47.600
..........
............ 77.00 (77)
.............
SIN:
Bentley PondPack (10.00.027.00)
9:47 AM
Bentley Systems, Inc.
7/2/2008
Type.... Runoff CN-Area
Name.... SF 15 PHS 1&2
Page 4.02
File.... K:A05\05-260\05261.19-Wendell Falls - SF 15 Phase 1\H-H\BMP15.1 Wet Pcnd.ppw
RUNOFF CURVE NUMBER DATA
..........................................................................
..........................................................................
impervious
Area Adjustment Adjusted
Soil/Surface Description CN acres ?cC oUC CN
---------------------------------- ---- --------- ----- ----- ------
Impervious Areas - Paved; curbs and 98 17.820 98.00
Open space (Lawns,parks etc.) - Fai 79 29.780 79.00
COMPOSITE AREA & WEIGHTED CN ---> 4'7.600 86.11 (86)
...........................................................................
SIN: Bentley Systems, Inc.
Bentley PondPack (10.00.027.00) 9:47 AM 7/2/2008
Type.... Unit Hyd. Summary Page 5.01
Name.... PRE Tag: 1 Event: 1 yr
File .... K:A05\05-260\05261.19-Wendell Falls - SF 1 Phase 1\H-H\.BMP15.I Wet Pond.ppw
Storm... TypeII 24hr Tag: 1
SCS UNIT HYDROGRAPH METHOD
STORM EVENT: 1 year storm
Duration = 24.0000 hrs Rain Depth = 3.0000 in
Pair, Dir = K:\05\05-260\05261.15+-Wendell Falls - SF 15 Phase 1\H-H\
Rain File -ID - - TypeII 24hr
Unit Hyd Type = Default Curvilinear
HYG Dir = K:A05\05-260\05261.19-Wendell Falls - SF 15 Phase 1\H-H\
HYG File - ID = work pad.hyg - PRE 1
Tc = .2500 hrs
Drainage Area = 47.600 acres Runoff CN-= 77
---------------------------------------- --
Computational Time Increment = .03333 hrs
Computed Peak Time - 12.0667 hrs
Computed Peak Flow - 60.63 cfs
Time Increment for HYG File - .0500 hrs
Peak Time, Interpolated Output - 12.0500 hrs
Peak Flow, Interpolated Output = 60.30 cfs
---------------------------------------------
DRAINAGE AREA
ID:PRE
CN = 77
Area = 47.600 acres
S = 2.9870 in
0.2S = .5974 in
Cumulative Runoff
-------------------
1.0710 in
4.248 ac-ft
HYG Volume--- 4.249 ac-ft (area under HYG curve)
***** SCS UNIT HYDROGRAPH PARAMETERS *****
Time Concentration, Tc = .25000 hrs (ID: PRE)
Computational Incr, Tm = .03333 hrs - 0.20000 Tp
Unit Hyd. Shape Fact or = 483.432 (37.46° under rising limb)
K = 483.43/645.333, K = 7491 (also, K = 2/(1+(Tr/Tp))
Receding/Rising, Tr/ Tp = 1.6698 (solved from K = .7491)
Unit peak, qp = 215.'73 cfs
Unit peak time Tp .16667 hrs
Unit receding limb, Tr = .66667 hrs
Total unit time, Tb = .83333 hrs
SIN: Bentley Systems, Inc.
Bentley PondPack (10.00.027.00) 9:47 AM 7/2/2008
Type.... Unit Hyd. (HYG output) Page 5.02
Name.... PRE Tag: 1 Event: 1 yr
File.... K:A05\05-260\05261.19-Wendell Falls - SF 15 Phase 1\H-H\B111P15.1 Wet Pond.ppw
Storm... TypeII 24hr Tag: 1
SCS UNIT HYDROGRAPH METHOD
STORM EVENT: 1 year storm
Duration = 24.0000 hrs Rain Depth = 3 .0000 in
Rain Dir = K:A05\05-260\05261.1 9-Wendell Falls - SF 15 Phase 1\H-H\
Rain File -ID = - TypeII 24hr
Unit Hyd Type = Default Curvilinear
HYG Dir = K:A05\05-260\05261..1 9-Wendell Falls - SF 15 Phase 1\H-H\
HYG File - ID = work pad.hyg - PRE 1
Tc = .2500 hrs
Drainage Area = 47.600 acres Runoff CN= 77
Calc.Increment = .03333 hrs Out. Incr.- .05 00 hrs
HYG Volume = 4.249 ac-ft
HY DROGRAPH ORDINATES (cf s)
Time Ou tput Time increment = .0500 hrs
hrs Time on left represents time for fi rst value in eac h row.
---------I-
10.4500 1 ----------------
.00 ----------------------
.00 .01 ----------
.03 ------ -------
.06
10.7000 .09 .13 .18 .23 .29
10.9500 .35 .41 .48 .56 .65
11.2000 .76 .88 1.01 1.16 1.32
11.4500 1.50 1.69 2.01 2.57 3.73
11.7000 5.61 8.79 13.26 20.43 30.96
11.9500 44.30 55.73 60.30 57.05 46.67
12.2000 35.73 27.16 21.47 17.86 15.22
12.4500 13.31 11.79 10.54 9.48 8.62
12.1000 7.94 7.45 7.07 6.79 6.54
12.9500 6.30 6.08 5.87 5.67 5.49
13.2000 5.33 5.19 5.06 4.93 4.82
13.4500 4.70 4.59 4.47 4.36 4.26
13.7000 4.16 4.07 3.98 3.89 3.81
13.9500 3.72 3.64 3.56 3.48 3.41
1.4.2000 3.36 3.31 3.27 3.24 3.20
14.4500 3.17 3.14 3.12 3.09 3.06
14.7000 3.03 3.00 2.98 2.95 2.92
14.9500 2.89 2.86 2.83 2.80 2.77
15.2000 2.75 2.72 2.69 2.66 2.63
15.4500 2.60 2.57 2.54 2.51 2.48
15.7000 2.45 2.42 2.39 2.36 2.33
15.9500 2.30 2.27 2.24 2.21 2.18
16.2000 2.16 2.14 2.13 2.12 2.11
16.4500 2.09 2.08 2.07 2.06 2.05
16.7000 2.04 2.03 2.02 2.01 2.00
16.9500 1.99 1.98 1.97 1.96 1.95
17.2000 1.94 1.93 1.92 1.90 1.89
17.4500 1.88 1.87 1.86 1.85 1.84
17.7000 1.83 1.82 1.81 1.80 1.79
SIN:
Bentley PondPack (10.00.027.00)
9:47 AM
Bentley Systems, Inc.
7/2/2008
Type.... Unit Hyd. HYG output) Page 5.03
Name.... PRE Tag: 1 Event: 1 ;Ilr
File.... K:A05\05-260\05261.19-Wendell Falls - SF 15 Phase 1\H-H\BMP15.1 i^det Pond.ppw
Storm... Typell 24hr Tag: 1
HYDROGRAPH ORDINATES (cfs)
Time Output Time increment - .0500 hrs
hrs
- Time on
----------- left represents
--------------- time for
------- - first value
--------
-
-- in each row.

17.9500 1
1.78
1.76
1.75 -
-
1.74 -------------
1.73
18.2000 1.72 1.71 1.70 1.69 1.68
18.4500 1.66 1.65 1.64 1.63 1.62
18.7000 1.61 1.60 1.59 1.58 1.56
18.9500 1.55 1.54 1.53 1.52 1.51
19.2000 1.50 1.48 1.47 1.46 1..45
19.4500 1.44 1.43 1.42 1.40 1.39
19.7000 1.38 1.37 1.36 1.35 1.33
19.9500 1.32 1.31 1.30 1.29 1.28
20.2000 i 1.27 1.27 1.26 1.26 1.26
20.4500 1 1.26 1.25 1.25 1.25 1.25
20.7000 1 1.24 1.24 1.24 1.24 1.24
20.9500 1.23 1.23 1.23 1.23 1.23
21.2000 1.22 1.22 1.22 1.22 1.22
21.4500 1 1.21 1.21 1.21 1.21 1.21
21.7000 1.20 1.20 1.20 1.20 1.20
21.9500 1.19 1.19 1.19 1.19 1.19
22.2000 1.18 1.18 1.18 1.18 1.18
22.4500 1.17 1.17 1.17 1.17 1.16
22.7000 1.16 1.16 1.16 1.16 1.15
22.9500 1.15 1.15 1.15 1.14 1.14
23.2000 1.14 1.14 1.14 1.13 1.13
23.4500 1 1.13 1.13 1.13 1.12 1.12
23.7000 1.12 1.12 1.12 1.11 1.11
23.9500 1 1.11 1.11 1.06 .93 .69
24.2000 I .45 .28 .17 .10 .06
24.4500 .04 .02 .01 .01 .00
24.7000 1 .00 .00
SIN: Bentley Systems, Inc.
Bentley PondPack (10.00.027.00) 9:47 AM 7/2/2008
Type.... Unit Hyd. Summary Page 5.04
Name.... PRE Tag: 10 Event: 10 yr
File.... K:A05\05- 260\05261.79-Wendell Falls - SF 15 Phase 1\H-H\BMP15.1 Wet Pond.ppw
Storm... RDU NOAA 1_'_- Tag: 10
SCS UT]IT HYDROGRAPH METHOD
STORM EVENT: 10 year storm
Duration = 23.9904 hrs Rain Depth = 4.9800 in
Rain Dar = K:A05\05-260\05261.19-Wendell Falls SF 15 Phase 1\H-H\
Rain File -ID - - RDU NOAA 10yr
Unit H••.d T}'pe = Default Curvilinear
HYG D.r - K:A05\05-260\05261.19-Wendell Falls - SF 15 Phase 1\H-H\
HYG Fale - ID = work pad.hyg - PRE 10
Tc - .2500 hrs
Drain.ge Area - 47.600 acres Runoff CN= 77
------------------------------------- ------
Computational Time Increment - .03333 hrs
Computed Peak Time = 12.2000 hrs
Computed Peak Flow = 137.91 cfs
Time Increment for HYG File = .0500 hrs
Peak Time, Interpolated Output = 12.2000 hrs
Peak !'low, Interpolated Output = 137.91 cfs
---------------------------------------------
DRAINAGE AREA
ID:PRE
CN = 77
Area = 47.600 acres
S = 2.9870 in
0.2S = .5974 in
Cumulative Runoff
-------------------
2.6063 in
10.338 ac-ft
HYG Volume... 10.337 ac-ft (area under HYG curve)
***** SCS UNIT HYDROGRAPH PARAMETERS *****
Time Concentration, Tc = .25000 hrs (ID: PRE)
Compu tational Incr, Tm = .03333 hrs = 0.20000 Tp
Unit Hyd. Shape Fact or = 483.432 (37.46% under rising limb)
K - 483.43/645.333, K = .7491 (also, K = 2/(1+(Tr/Tp))
Reced ing/Rising, Tr/Tp = 1.6698 (solved from K - .7491)
Unit peak, qp = 215.73 cfs
Unit peak time Tp = .16667 firs
Unit receding limb, Tr = .66667 hrs
Total unit time, Tb = .83333 hrs
SIN: Bentley Systems, Inc.
Bentley PondPack (10.00.027.00) 9:47 AM 7/2/2008
Type.... Unit Hyd. (HYG output) Page 5.05
Name.... PRE Tag: 10 Event: 10 yr
File.... 1<.:A05\05-260\05261.19-Wendell Falls - SF 15 Phase 1\H-H\BMP15.1 Wet Pond.ppw
Storm... BDU NOAA 10yr Tag: 10
SCS UNIT HYDROGRAPH METHOD
STORM EVENT: 10 year storm
Duration = 23.9904 hrs Rain Depth = 4.9800 in
Rain Dir = K:A05\05-260 \05261.19 -Wendell Falls - SF 15 Phase 1\H-H\
Rain File -ID = - RDU NOAA 10yr
Unit Hyd Type = Default Curv ilinear
HYG Dir = K:A05\05-260 \05261.19 -Wendell Falls - SF 15 Phase 1\H-H\
HYG File - ID - work pad.hyg - PRE 10
Tc = .2500 hrs
Drainage Area = 47.600 acres Runoff CN= 77
Calc.Increment = .03333 hrs Out.I ncr.= .0 500 hrs
HYG Volume - 10.337 ac-ft
HY DROGRAPH ORDIN ATES (cfs )
Time I Ou tput Time incr ement = . 0500 hrs
firs Time on left represents tim e for fir st value in each row.

7.7500 -----------------
.00 --------------
.00 -- -----
.01 --------
.02 --------------
.03
8.0000 .05 .07 .09 .11 .13
8.2500 .14 .16 .18 .20 .22
8.5000 .24 .26 .28 .30 .32
8.7500 .34 .36 .37 .39 .41
9.0000 .43 .47 .54 .65 .78
9.2500 .88 .97 1.04 1.11 1.17
9.5000 1.23 1.29 1.34 1.40 1.45
9.7500 1.50 1.55 1.60 1.65 1.70
10.0000 1.75 1.80 1.85 1.90 1.95
10.2500 2.00 2.04 2.09 2.14 2.18
10.5000 2.23 2.33 2.54 2.85 3.18
10.7500 3.44 3.64 3.80 3.93 4.05
11.0000 4.15 4.25 4.34 4.43 4.52
11.2500 4.61 4.70 4.78 4.86 4.94
11.5000 5.05 5.74 7.58 10.65 13.81
11.7500 16.47 19.37 24.43 31.19 39.25
12.0000 I 49.49 67.52 94.62 122.86 137.91
12.2500 I 133.62 117.67 97.15 77.76 63.14
12.5000 52.79 45.65 38.40 30.54 23.59
12.7500 18.75 15.66 13.85 12.70 12.06
13.0000 11.67 11.46 11.34 11.28 11.25
13.2500 11.24 11.25 11.27 11.29 11.30
13.5000 I 11.30 11.13 10.64 9.84 9.06
13.7500 8.50 8.14 7.94 7.82 7.74
14.0000 I 7.70 7.68 7.67 7.66 7.66
14.2500 I 7.66 7.66 7.67 7.67 7.68
14.5000 7.69 7.70 7.70 7.71 7.72
14.7500 7.72 7.73 7.74 7.74 7.75
15.0000 7.75 7.58 7.12 6.38 5.67
SIN: Bentley Systems, Inc.
Bentley PondPack (10.00.027.00) 9:47 AM 7/2/2008
Type.... Unit Hyd. (HYG output) Page 5.06
Name.... PRE Tag: 10 Event: 10 yr
File.... K:\05\05-260\05261.19-Wendell Falls - SF 15 Phase 1\H-H\,BMP15.1 Wet Pond.ppw
Storm... RDU NOAH l0yr Tag: 10
HYDROGRAPH ORDINATES (cfs)
Time Output Time increment = .0500 hrs
hrs
--------- I- Time on
---------- - left represents
--------------- time for
--------- first value in
---------------- each row.
---

15.2500
5.16
4.83
4.65
4.53 -------
4.46
15.5000 4.41 4.39 4.38 4.37 4.36
15.7500 4.36 4.36 4.35 4.35 4.36
16.0000 4.36 4.37 4.37 4.37 4.37
16.2500 4.38 4.38 4.38 4.38 4.38
16.5000 4.39 4.39 4.39 4.38 4.38
16.7500 4.39 4.39 4.39 4.40 4.40
17.0000 4.40 4.41 4.41 4.41 4.41
17.2500 4.41 4.41 4.41 4.41 4.41
17.5000 4.42 4.42 4.42 4.43 4.43
17."7500 4.43 4.43 4.43 4.43 4.44
18.0000 4.43 4.34 4.09 3.70 3.33
18.2500 3.07 2.90 2.81 2.75 2.70
18.5000 2.68 2.66 2.66 2.66 2.66
18.7500 2.65 2.65 2.65 2.65 2.65
19.0000 2.66 2.66 2.66 2.65 2.65
19.2500 2.65 2.66 2.66 2.66 2.66
19.5000 2.65 2.66 2.66 2.67 2.67
19.7500 2.66 2.66 2.66 2.66 2.67
20.0000 2.67 2.67 2.67 2.67 2.67
20.2500 2.68 2.67 2.67 2.67 2.66
20.5000 2.67 2.67 2.68 2.68 2.67
20.7500 2.67 2.67 2.67 2.68 2.68
21.0000 I 2.68 2.67 2.67 2.67 2.68
21.2500 2.68 2.68 2.68 2.68 2.68
21.5000 I 2.68 2.69 2.69 2.69 2.68
21.7500 2.68 2.68 2.68 2.69 2.69
22.0000 2.69 2.68 2.68 2.68 2.69
22.2500 2.69 2.69 2.69 2.69 2.69
22.5000 2.69 2.70 2.70 2.70 2.69
22.7500 I 2.69 2.69 2.69 2.70 2.70
23.0000 2.70 2.69 2.69 2.69 2.70
23.2500 I 2.71 2.70 2.70 2.70 2.70
23.5000 2.70 2.71 2.71 2.71 2.70
23.7500 2.70 2.70 2.70 2.71 2.71
24.0000 2.70 2.55 2.16 1.58 1.02
24.2500 .63 .38 .23 .14 .09
24.5000 .05 .03 .02 .01 .00
24.7500 .00 .00
SIN: Bentley Systems, Inc.
Bentley PondPack (10.00.027.00) 9:47 AM 71212008
Type.... Unit Hyd. Summary Page 5.07
Name.... PRE Tag: 100 Event: 100 yr
File.... K:A05\05-2.60\05261.19-Wendell F,-ills - SF 15 Phase 1\H-11\BMP15.1 Wet Pond.ppw
Storm... RD[T NOPT-, 100yr Tag: 100
SCS UNIT HYDROGRAPH METHOD
STORM EVENT: 100 year storm
Duration - 23.9990 hrs Rain Depth = 7.3700 in
Rain Dir = K:A05\05-260\05261.19-Wendell Falls - SF 15 Phase 1\H-H\
Rain File -ID = - RDU NOAA 100yr
Unit Hyd Type = Default Curvilinear
HYG Dir = K,:\05\05-260\05261.19-Wendell Falls - SF 15 Phase 1\H-H\
HYG File - ID work pad.hyg - PRE 100
To = .2500 hrs
Drainage Area = 47.600 acres Runoff CN= 7?
--------------------------------------------
Computational Time Increment = .03333 hrs
Computed Peak Time = 12.2000 hrs
Computed Peak Flow = 206.51 cfs
Time Increment for HYG File = .0500 hrs
Peak Time, Interpolated Output 12.2000 hrs
Peak Flow, Interpolated Output = 206.51 cfs
--------------------------------------------
DRAINAGE AREA
ID:PRE
CN = 77
Area = 47.600 acres
S = 2.9870 in
0.25 = .5974 in
Cumulative Runoff
-------------------
4.6998 in
18.642 ac-ft
HYG Volume... 18.641 ac-ft (area under HYG curve)
***** SCS UNIT HYDROGRAPH PARAMETERS *****
Time Concentration, To = .25000 hrs (ID: PRE)
Compu tational Incr, Tm = .03333 hrs = 0.20000 Tp
Unit Hyd. Shape Factor = 483.432 (37.46% under rising limb)
K = 483.43/645.333, K - .7491 (also, K - 2/(l+(Tr/Tp))
Reced ing/Rising, Tr/Tp = 1.6698 (solved from K - .7491)
Unit peak, qp = 215.73 cfs
Unit peak time Tp = .16667 hrs
Unit receding limb, Tr = .66667 hrs
Total unit time, Tb = .83333 hrs
SIN: Bentley Systems, Inc.
Bentley PondPack (10.00.027.00) 9:47 AM 7/2/2008
Type.... Unit Hyd. (HYG output) Page 5.08
Name.... PRE Tag: 100 Event: 100 yr
File.... K:A05\05-260\05261.19-Wendell Falls - SF 15 Phase 1\H-H\BMP15.1 Wet Pond.ppw
Storm... RDU 11OAA 100yr 'Fag: 100
SCS UNIT HYDROGRAPH METHOD
STORM EVENT: 100 year storm
Duration = 23.9990 hrs Rain Depth = 7.3700 in
Rain Dir = K:A05\05-260\05261.19-Wendell Falls - SF 15 Phase 1\H-H\
Rain File -ID = - RDU NOAA 100yr
Unit Hyd Type = Default Curvilinear
HYG Dir. = K:A05\05-260\05261.19-Wendell Falls - SF 1-5 Phase 1\H-H\
HYG File - ID = work pad.hyg - PRE 100
Tc = .2 00 hrs
Drainage Area - 47.600 acres Runoff CN= 77
Calc.Increment= .0'333 hrs Out.Incr.= .0500 hrs
HYG Volume = 18.641 ac-ft
HYDROGRAPH ORDINATES (cfs)
Time I Output Time increment = .0500 hrs
hrs Time on left represents time for first value in each row.
---------I-
6.1000 1 -----------
.00 ---------------
.00 ----------
.01 ------------
.02 -------------
.05
6.3500 .09 .13 .18 .23 .28
6.6000 .34 .39 .44 .49 .54
6.8500 .59 .64 .69 .74 .79
7.1000 .84 .89 .94 .98 1.03
7.3500 1.08 1.12 1.17 1.21 1.26
7.6000 1.30 1.35 1.39 1.43 1.48
7.8500 1 1.52 1.56 1.60 1.64 1.68
8.1000 1.73 1.77 1.81 1.85 1.89
8.3500 1.93 1.97 2.00 2.04 2.08
8.6000 2.12 2.15 2.19 2.23 2.26
8.8500 2.30 2.33 2.37 2.40 2.51
9.1000 2.75 3.15 3.56 3.89 4.13
9.3500 4.31 4.45 4.57 4.68 4.77
9.6000 4.86 4.95 5.03 5.12 5.20
9.8500 I 5.28 5.36 5.43 5.50 5.58
10.1000 5.65 5.72 5.80 5.87 5.94
10.3500 6.01 6.07 6.14 6.21 6.47
10.6000 7.14 8.27 9.43 10.34 10.98
10.8500 11.42 11.77 12.04 12.28 12.49
11.1000 12.68 12.86 13.03 13.19 13.35
11.3500 1 13.50 13.64 13.79 13.94 15.34
11.6000 19.47 26.69 34.11 40.14 45.81
11.8500 54.64 66.28 79.10 93.07 115.16
12.1000 149.48 186.84 206.51 200.02 178.42
12.3500 151.16 125.25 105.11 90.62 80.41
12.6000 69.30 56.12 44.06 35.45 29.96
12.8500 26.76 24.72 23.58 22.88 22.50
13.1000 22.28 22.16 22.09 22.06 22.06
13.3500 22.07 22.09 22.11 22.14 21.79
SIN: Bentley Systems, Inc.
Bentley PondPack (10.00.027.00) 9:47 AM 7/2/2008
Type.... Unit Hyd. (HYG output) Page 5.09
Name.... PRE Tag: 100 Event: 100 yr
File.... K:A05\05-260\05261.19-Wendell Falls - SF 15 Phase 1\H-H\HMP15.1 Wet Pond.ppw
Storm... RDU NOAA 100yr Tag: 100
HYDROGRAPH ORDINATES (cfs)
Time Output Time increment - .0500 hrs
hrs I
--------- I- Time on
----------- left represent
-------------- s time for
---------- first value in
---------------- each row.
----------
13.6000 20.65 18.63 16.62 15.12 14.19
13.8500 13.65 13.30 13.11 12.98 12.91
14.1000 12.87 12.85 12.83 12.83 12.83
14.3500 12.85 12.86 12.86 12.86 12.87
14.6000 12.87 12.88 12.89 12.89 12.90
14.8500 12.90 12.91 12.92 12.92 12.73
15.1000 12.12 11.04 9.96 9.15 8.65
15.3500 1 8.36 8.17 8.07 8.00 7.96
15.6000 7.93 7.92 7.91 7.91 .91
15.8500 7.92 7.92 7.92 7.92 7.92
16.1000 7.92 7.92 7.93 7.93 7.93
16.3500 7.93 7.94 7.94 7.94 7.94
16.6000 7.95 7.96 7.96 7.95 7.96
16.8500 7.96 7.96 7.96 7.96 7.96
17.1000 96 7.97 7.97 7.97 7.98
17.3500 7.98 7.99 7.99 7.99 7.99
17.6000 1 7.99 7.99 7.99 7.99 7.99
17.8500 1 7.99 8.00 8.00 8.00 7.85
18.1000 1 7.38 6.56 5.73 5.12 4.73
18.3500 1 4.51 4.36 4.28 4.23 4.20
18.6000 4.18 4.17 4.16 4.15 4.15
18.8500 4.16 4.17 4.16 4.16 4.16
19.1000 4.16 4.16 4.16 4.16 4.16
19.3500 4.16 4.16 4.16 4.16 4.16
19.6000 4.17 4.17 4.17 4.17 4.17
19.8500 4.16 4.16 4.16 4.17 4.16
20.1000 4.16 4.17 4.17 4.17 4.17
20.3500 4.18 4.18 4.18 4.17 4.17
20.6000 4.17 4.17 4.17 4.17 4.17
20.8500 4.17 4.17 4.17 4.17 4.18
21.1000 4.18 4.19 4.18 4.18 4.18
21.3500 4.18 4.18 4.18 4.18 4.18
21.6000 4.18 4.18 4.18 4.18 4.18
21.8500 4.19 4.19 4.19 4.19 4.19
22.1000 4.19 4.18 4.19 4.19 4.19
22.3500 4.19 4.19 4.19 4.19 4.19
22.6000 4.20 4.20 4.20 4.19 4.19
22.8500 4.19 4.19 4.19 4.19 4.19
23.1000 4.19 4.19 4.19 4.19 4.20
23.3500 4.20 4.21 4.20 4.20 4.20
23.6000 4.20 4.20 4.20 4.20 4.20
23.8500 4.20 4.20 4.20 4.20 4.03
24.1000 3.52 2.62 1.72 1.05 .63
24.3500 .39 .24 .14 .09 .05
24.6000 .03 .02 .01 .00 .00
S/N: Bentley Systems, Inc.
Bentley PondPack (10.00.027.00) 9:47 AM 7/2/2008
Type.... Unit Hyd. Summary Page 5.10
Name.... SF 15 PHS 1&2 Tag: 1 Event: 1 yr
File.... K:A05\05-260\05261.19-Wendell Falls - SF 15 Phase 1\H-H\BMP15.1 Wet Pond.ppw
Storm... TypeII 24hr Tag: 1
SCS UNIT HYDROGRAPH3 METHOD
STORM EVENT: 1 year storm
Duration = 24.0000 hrs Rain Depth = 3.0000 in
Rain Dir. = K:\05\05-260\05261.19-Wendell Falls - SF 15 Phase 1\H-H\
Rain File -ID = - TypeII 24hr
Unit Hyd Type = Triangular
HYG Dir = K:A05\05-260\05261.19-Wendell Falls - SF 15 Phase 1\11-H\
HYG File - ID = work pad.hyg - SF 15 PHS 1&2 1
Tc = .1500 hrs
Drainage Area = 47.600 acres Runoff CN= 86
---------------------------- ----------------
Computational Time Increment = .02000 hrs
Computed Peak Time = 12.0400 hrs
Computed Peak Flow = 89.43 cfs
Time Increment for HYG File = .0500 hrs
Peak Time, Interpolated Output - 12.0500 hrs
Peak Flow, Interpolated Output 88.72 cfs
DRAINAGE AREA
ID:SF 15 PHS 1&2
CN = 86
Area = 47.600 acres
S = 1.6279 in
0.2S = .3256 in
Cumulative Runoff
------------------
1.6625 in
6.594 ac-ft
HYG Volume... 6.594 ac-ft (area under HYG curve)
***** SCS UNIT HYDROGRAPH PARAMETERS *****
Time Concentration, Tc = .15000 hrs (ID: SF 15 PHS 1&2)
Compu tational Incr, Tm = .02000 hrs = 0. 20000 Tp
Unit Hyd. Shape Fact or = 252.000 (19.52° under rising limb)
K = 252.00/645.333, K = .3905 (also, K = 2/(1+(Tr/Tp))
Reced ing/Rising, Tr/Tp = 4.1217 (solved from K = .3905)
Unit peak, qp = 187.43 cfs
Unit peak time Tp = .10000 hrs
Unit receding limb, Tr = .41217 hrs
Total unit time, Tb = .51217 hrs
SIN: Bentley Systems, Inc.
Bentley PondPack (10.00.027.00) 9:47 AM 7/2/2008
Type.... Unit Hyd. (HYG output) Page 5.11
Name.... SF 15 PHS 1&2 Tag: I Event: 1 yr
File.... K:A05\05-260\05261.19-Wendell Falls - SF 15 Phase 1\H-H\B1,1PI5.1 Wet Pond.ppw
Storm ... TypeII 24hr Tag: 1
SCS UNIT HYDROGRAPH METHOD
STORM EVENT: 1 year storm
Duration = 24.0000 hrs Rain Depth = 3 .0000 in
Rain Dir = K:\05\05-260 \05261 .19-Wendell Falls - SF 15 Phase 1\H-H\
Rain File -ID = - TypeII 2 4hr
Unit Hyd Type = Triangular
HYG Dir = K:\05\05-260 \05261 .19-Wendell Falls - SF 15 Phase 1\H-H\
HYG File - ID = work pad.hyg - SF 15 PHS 1&2 1
Tc = .1500 hrs
Drainage Area = 47.600 acres Runo ff CN= 86
Ca1c.Increment = .02000 hrs Ou t.Incr.= .05 00 hrs
HYG Volume = 6.594 ac-ft
HY DROGRAPH ORDIN ATES ( cfs)
Time Ou tput Time incr ement = .0500 hrs
hrs Time on left represents tim e for first value in eac h row.
---------I
7.5000 -----------------
.00 --------------
.00 ------
.00 ------------
.01 ------ -------
.02
"7.7500 ( .03 .03 .05 .06 .07
8.0000 .08 .09 .11 .12 .13
8.2500 .15 .17 .18 .20 .22
8.5000 .24 .26 .28 .30 .32
8.7500 .35 .37 .40 .42 .45
9.0000 .48 .50 .53 .56 .58
9.2500 .61 .63 .66 .68 .70
9.5000 .72 .74 .77 .80 _83
9.7500 .86 .90 .94 .99 1.03
10.0000 I 1.08 1.13 1.18 1.24 1.30
10.2500 I 1.37 1.44 1.51 1.58 1.66
10.5000 I 1.74 1.83 1.92 2.02 2.13
10.7500 I 2.24 2.37 2.50 2.64 2.78
11.0000 I 2.93 3.10 3.28 3.49 3.74
11.2500 4.01 4.31 4.64 4.99 5.36
11.5000 5.75 6.67 8.30 11.25 15.73
11.7500 22.18 30.69 43.53 61.53 77.45
12.0000 87.58 88.72 80.40 68.81 57.30
12.2500 46.23 35.94 27.25 20.92 16.91
12.5000 I 14.64 13.48 12.40 11.47 10.69
12.7500 I 10.06 9.53 9.10 8.73 8.41
13.0000 8.12 7.84 7.58 7.33 7.11
13.2500 6.91 6.72 6.55 6.38 6.22
13.5000 6.06 5.91 5.76 5.62 5.49
13.7500 5.36 5.23 5.11 5.00 4.88
14.0000 4.77 4.66 4.56 4.47 4.40
14.2500 4.33 4.27 4.22 4.18 4.13
14.5000 4.10 4.06 4.02 3.98 3.94
14.7500 3.90 3.86 3.82 3.78 3.75
SIN: Bentley Systems, Inc.
Bentley PondPack (10.00.027.00) 9:47 AM 7/2/2008
Type.... Unit Hyd. (HYG output) Page 5.12
Name.... SF 15 PHS 1&2 Tag: 1 Event: 1, yr
File.... K:A05\05-260\05261.19-Wendell Falls - SF 15 Phase l\H-H\BMP15.1 Wet Pond.ppw
Storm... TypeII 24hr Tag: 1
HYDROGRAPH ORDINATES (cfs)
Time I Output Time increment = .0500 hrs
hrs
---------I- Time on
----------- left represent
-------------- s time for
---------- first value in
-------
-- each row.

15.0000 1
3.71
3.67
3.63 -
------
3.59 ----------
3.55
15.2500 1 3.51 3.47 3.43 3.39 3.35
15.5000 1 3.31 3.27 3.23 3.19 3.15
15.7500 1 3.11 3.07 3.03 2.99 2.95
16.0000 1 2.90 2.87 2.83 2.80 2.77
16.2500 1 2.75 2.73 2.71 2.69 2.68
16.5000 1 2.66 2.65 2.63 2.62 2.61
16.7500 1 2.59 2.58 2.56 2.55 2.53
17.0000 1 2.52 2.51 2.49 2.48 2.46
17.2500 2.45 2.43 2.42 2.41 2.39
17.5000 1 2.38 2.36 2.35 2.33 2.32
17.7500 2.31 2.29 2.28 2.26 2.25
18.0000 1 2.23 2.22 2.20 2.19 2.17
18.2500 1 2.16 2.15 2.13 2.12 2.10
18.5000 2.09 2.07 2.06 2.04 2.03
18.7500 1 2.01 2.00 1.98 1.97 1.96
19.0000 1 1.94 1.92 1.91 1.90 1.88
19.2500 1 1.87 1.85 1.84 1.82 1.81
19.5000 1 1.79 1.78 1.76 1.75 1.73
19.7500 1 1.72 1.70 1.69 1.67 1.66
20.0000 1.64 1.63 1.62 1.61 1.60
20.2500 1.59 1.58 1.58 1.57 1.57
20.5000 1 1.57 1.57 1.56 1.56 1.56
20.7500 1 1.55 1.55 1.55 1.55 1.54
21.0000 1 1.54 1.54 1.53 1.53 1.53
21.2500 1.53 1.52 1.52 1.52 1.51
21.5000 I 1.51 1.51 1.51 1.50 1.50
21.7500 1 1.50 1.49 1.49 1.49 1.49
22.0000 1 1.48 1.48 1.48 1.48 1.47
22.2500 1 1.47 1.47 1.46 1.46 1.46
22.5000 1 1.46 1.45 1.45 1.45 1.44
22.7500 1 1.44 1.44 1.43 1.43 1.43
23.0000 1 1.43 1.42 1.42 1.42 1.41
23.2500 1 1.41 1.41 1.41 1.40 1.40
23.5000 1 1.40 1.39 1.39 1.39 1.39
23.7500 1 1.38 1.38 1.38 1.37 1.37
24.0000 1 1.37 1.27 1.05 .80 .59
24.2500 .41 .26 .15 .07 .02
24.5000 .00
SIN: Bentley Systems, Inc.
Bentley PondPack (10.00.027.00) 9:47 AM 7/2/2008
Type.... Unit Hyd_ Summary Page 5.1
Name.... SF 15 PHS 1&2 Tag: 10 Event: 10 yr
File.... K: \05\05-260\05261.19-Wendell Falls - SF 15 Phase 1\H-H\BMP15.I Wet Pond.ppw
Storm... RDU NOAA 10r Tag: 10
SCS UNIT HYDROGRAPH METHOD
STORM EVENT: 10 year storm
Duration = 23.9904 hrs Rain Depth = 4.9800 in
Rain Dir = K:\05\05-260\05261.19-Wendell Falls - SF 15 Phase 1\H-H\
Rain File -ID = - RDU NOAA 10yr
Unit Hyd Type = Triangular
HYG Dir = K:A05\05-260\05261.19-Wendell Falls - SF 15 Phase 1\H-H\
HYG File - ID = work pad.hya - SF 15 PHS 1&2 10
Tc = .1500 hrs
Drainage Area = 47.600 acres Runoff CN= 86
-----------------------------------
Computational Time Increment = .02000 hrs
Computed Peak Time = 12.2000 hrs
Computed Peak Flow - 164.25 cfs
Time Increment for HYG File = .0500 hrs
Peak Time, Interpolated Output - 12.2000 hrs
Peak Flow, Interpolated output = 164.25 cfs
- ------------------------------------------
DRAINAGE AREA
ID:SF 15 PHS 1&2
CN = 86
Area = 47.600 acres
S = 1.6279 in
0.2S = .3256 in
Cumulative Runoff
-------------------
3.4483 in
13.678 ac-ft
HYG Volume... 13.679 ac-ft (area under HYG curve)
***** SCS UNIT HYDROGRAPH PARAMETERS *****
Time Concentration, Tc = .15000 hrs (ID: SF 15 PHS 1&2)
Compu tational Incr, Tm = .02000 hrs - 0. 20000 Tp
Unit Hyd. Shape Fact or = 252.000 (19.52 under rising limb)
K = 252.00/645.333, K = .3905 (also, K = 2/(1+(Tr/Tp))
Reced ing/Rising, Tr/ Tp = 4.1217 (solved from K = .3905)
Unit peak, qp = 187.43 cfs
Unit peak time Tp = .10000 hrs
Unit receding limb, Tr = .41217 hrs
Total unit time, Tb = .51217 hrs
SIN: Bentley Systems, Inc.
Bentley PondPack (10.00.027.00) 9:47 AM 7/2/2008
Type.... Unit Hyd. (HYG output) Page 5.14
Name.... SF 15 PHS 1&2 Tag: 10 Event: 10 yr
File.... K:A05\05-260\05261.19-Wendell Falls - SF 15 Phase 1\H-H\BMP15.1 Wet Pond.ppw
Storm... RDU NOAA 10yr Tag: 10
SCS UNIT HYDROGRAPH METHOD
STORM EVENT: 10 year storm
Duration = 23.9904 hrs Rain Depth - 4.9800 in
Rain Dir = K:A05\05-260 \05261 .19-Wendell Falls - SF 15 Phase 1\H-H\
Rain File -ID = - RDU NOAA 10yr
Unit Hyd Type = Triangular
HYG Dir = K:A05\05-260 \05261 .19-Wendel1 Falls - SF 15 Phase 1\H-H\
HYG File - ID = work pad.hyg - SF 15 PHS 1&2 10
Tc = .1500 hrs
Drainage Area = 47.600 acres Runo ff CN= 86
Caic.Increment = .02000 hrs Ou t.Incr.= .0 500 hrs
HYG Volume - 13.679 ac-ft
HY DROGRAPH ORDIN ATES ( cf.s)
Time Ou tput Time incr ement = .0500 his
hrs Time on left represents tim e for first value in each row.
--- ------
4.%1500 ----------------
.00 --------------
.00 ------
.00 -----------
.01 --------------
.02
5.1000 .03 .04 .05 .06 .08
5.3500 .09 .10 .11 .13 .14
5.6000 .15 .16 .18 .19 .20
5.8500 .21 .23 .24 .25 .28
6.1000 .32 .38 .43 _48 .53
6.3500 .58 .62 .66 .69 .72
6.6000 .75 .78 .81 .84 .87
6.8500 .90 .93 .96 .98 1.01
7.1000 1.04 1.07 1.10 1.12 1.15
7.3500 1.18 1.20 1.23 1.25 1.28
7.6000 1.30 1.33 1.35 1.38 1.40
7.8500 1.43 1.45 1.47 1.50 1.52
8.1000 1.54 1.51 1.59 1.61 1.63
8.3500 1.65 1.68 1.70 1.72 1.74
8.6000 1.76 1.79 1.81 1.83 1.85
8.8500 I 1.87 1.89 1.91 1.93 2.07
9.1000 2.36 2.68 2.96 3.21 3.43
9.3500 3.62 3.77 3.88 3.95 4.01
9.6000 4.06 4.12 4.17 4.22 4.27
9.0500 4.32 4.37 4.42 4.47 4.52
10.1000 I 4.57 4.62 4.66 4.71 4.76
10.3500 I 4.80 4.84 4.89 4.94 5.18
10.6000 ( 5.66 6.16 6.62 7.02 7.37
10.8500 7.65 7.88 8.05 8.16 8.24
11.1000 8.32 8.39 8.47 8.55 8.62
11.3500 8.69 8.76 8.83 8.98 10.82
11.6000 14.70 18.86 22.60 26.10 31.79
11.8500 40.69 49.62 59.93 74.89 102.13
12.1000 138.08 160.26 1 64.25 157.80 143.52
SIN: Bentley Systems, Inc.
Bentley PondPack (10.00.027.00) 9:47 AM 7/2/2008
Type.... Unit Hyd. (HYG output) Page 5.15
Name.... SF 15 PHS 1&2 Tag: 10 Event: 10 yr
File.... K:A05\05-260\05261.19-Wendell Falls - SF 15 Phase 1\H-H\BMP15.1 Wet Pond.ppw
Storm... RDU NOR:-, 10yr Tag: 10
HYDROGRAPH ORDINATES (cfs)
Time Output Time increment - .0500 hrs
hrs
---------
- Time on
----------- left represent
----------
---- s time for

---------- first value

------------- in each row.

------
-
--
I
12.3500 124.36 104.58 86.03 69.43 -
---
54.65
12.6000 42.32 33.08 26.62 22.14 18.85
12.8500 1 16.32 14.50 13.45 13.11 13.11
13.1000 13.12 13.13 13.14 13.15 13.17
13.3500 13.18 13.18 13.19 13.18 12.82
13.6000 12.08 11.32 10.65 10.09 9.63
13.8500 9.28 9.03 8.89 8.84 8.85
14.1000 1 8.85 8.85 8.86 8.86 8.86
14.3500 8.86 8.86 8.87 8.87 8.88
14.6000 8.88 8.89 8.89 8.89 8.90
14.8500 8.90 8.90 8.91 8.89 8.56
15.1000 7.89 7.21 6.61 6.10 5.69
15.3500 5.38 5.15 5.02 4.98 4.98
15.6000 4.98 4.98 4.99 4.98 4.98
15.8500 9.98 4.98 4.98 4.98 4.99
16.1000 4.99 4.99 4.99 4.99 5.00
16.3500 4.99 5.00 5.00 5.00 5.00
16.6000 1 4.99 4.99 5.00 5.00 5.00
16.8500 1 5.00 5.00 5.00 5.01 5.01
17.1000 5.01 5.01 5.01 5.01 5.01
17.3500 5.00 5.01 5.01 5.01 5.01
17.6000 5.02 5.02 5.02 5.02 5.02
17.8500 5.02 5.02 5.03 5.01 4.84
18.1000 4.49 4.13 3.82 3.57 3.36
18.3500 I 3.20 3.08 3.01 2.99 2.99
18.6000 I 3.00 3.00 3.00 2.99 2.99
18.8500 2.99 3.00 3.00 3.00 3.00
19.1000 I 3.00 2.99 2.99 3.00 3.00
19.3500 3.00 3.00 3.00 3.00 3.00
19.6000 3.00 3.01 3.00 3.00 3.00
19.8500 I 3.00 3.00 3.01 3.01 3.00
20.1000 I 3.00 3.01 3.01 3.01 3.01
20.3500 3.00 3.00 3.00 3.01 3.01
20.6000 3.01 3.01 3.00 3.00 3.00
20.8500 3.01 3.01 3.01 3.01 3.00
21.1000 3.00 3.01 3.01 3.01 3.01
21.3500 I 3.01 3.01 3.01 3.01 3.02
21.6000 I 3.01 3.01 3.01 3.01 3.01
21.8500 I 3.02 3.02 3.01 3.01 3.01
22.1000 I 3.01 3.01 3.02 3.02 3.01
22.3500 3.01 3.01 3.01 3.02 3.02
22.6000 3.02 3.02 3.01 3.01 3.01
22.8500 I 3.02 3.02 3.02 3.02 3.01
23.1000 3.01 3.02 3.02 3.02 3.02
23.3500 3.02 3.02 3.02 3.02 3.03
SIN: Bentley Systems, Inc.
Bentley PondPack (10.00.027.00) 9:47 AM 7/2/2008
Type.... Unit Hyd. (HYG output) Page 5.16
Name.... SF 15 PHS 1&2 Tag: 10 Event: 10 yr
File.... K:A05\05-260\05261.19-Wendell Falls - SF 15 Phase 1\H-H\BMP15.1 Wet Pcnd.ppw
Storm... RDO NOAA 10yr Tag: 10
HYDROGRAPH ORDINATES (cfs)
Time Output Time increment - .0500 hrs
hrs
-
--------- Time on
----------- left represents
--------------- time for
--------- first value in
--------------- each row.
-----------
I
23.6000 3.02 3.02 3.02 3.02 3.02
23.8500 3.03 3.03 3.02 3.00 2.73
24.1000 2.21 1.68 1.23 .84 .53
24.3500 .29 .12 .03 .00
SIN: Bentley Systems, Inc.
Bentley PondPack (10.00.027.00) 9:47 AM 7/2/2008
Type.... Unit Hyd. Summary Page 5.17
Name.... SF 15 PHS 1&2 Tag: 100 Event: 100 yr
File.... F: .1 Falls - SF 15 Phase 1\H-H\BMP15.1 Wet Pond.ppw
Storm... RDU NOAA 100yr Tag: --? `-?
SCS UNIT HYDROGRAPH METHOD
STORM EVENT: 100 year storm
Duration = 23.9950 hrs Rain Depth = 7.3700 in
Rain Dir - K:\05\05-260\05261.19-Wendell Falls - SF 15 Phase 7\H-H\
Rain File -ID = - RDU NOAA 100yr
Unit Hyd Type = Triangular
HYG Dir = 1<.:A05\05-260\05261.19-Wendell Falls - SF 15 Phase 1\H-H\
HYG File - ID = work pad.hyg - SF 15 PHS 1&2 100
Tc = .1500 hrs
Drainage Area = 47.600 acres Runoff CN- 86
---------------------------------------------
Computational Time Increment - .02000 hrs
Computed Peak Time - 12.1800 hrs
Computed Peak Flow 225.12 cfs
Time Increment for HYG File = .0500 his
Peak Time, Interpolated Output = 12.2000 hrs
Peak Flow, Interpolated Output = 224.59 cfs
--------------------------------------------
DRAINAGE AREA
ID:SF 15 PHS 1&2
CN = 86
Area = 47.600 acres
S = 1.6279 in
0.2S = .3256 in
Cumulative Runoff
-------------------
5.7221 in
22.698 ac-ft
HYG Volume... 22.698 ac-ft (area under HYG curve)
***** SCS UNIT HYDROGRAPH PARAMETERS *****
Time Concentration, Tc = .15000 hrs (ID: SF 15 PHS 1&2)
Compu tational Incr, Tm = .02000 hrs = 0. 20000 Tp
Unit Hyd. Shape Fact or = 252.000 (19.52° under rising limb)
K = 252.00/645.333, K = .3905 (also, K = 2/(1+(Tr/Tp))
Reced ing/Rising, Tr/Tp = 4.1217 (solved from K = .3905)
Unit peak, qp = 187.43 cfs
Unit peak time Tp = .10000 hrs
Unit receding limb, Tr = .41217 hrs
Total unit time, Tb = .51217 hrs
SIN:
Bentley PondPack (10.00.027.00)
9:47 AM
Bentley Systems, Inc.
7/2/2008
Type.... Unit Hyd. (HYG output) Page 5.18
Name.... SF 15 PHS 1&2 Tag: 100 Event: 100 yr
File.... K:A05\05-260\05261.19-Wendell Falls - SF 15 Phase 1\H-H\B111P15.1 Wet Pond.ppw
Storm... RDU NOAA 100yr Tag: 100
SCS UNIT HYDROGRAPH METHOD
STORM EVENT: 100 year storm
Duration = 23.9990 hrs Rain Depth = 7.3700 in
Rain Dir - K:A05\05-260 \05261.19 -Wendell Falls - SF 15 Phase 1\H-H\
Rain File -ID - - RDU NOAA 100yr
Unit Hyd Type - Triangular
HYG Dir = K:A05\05-260 \05261.19 -Wendell Falls - SF 15 Phase 1\H-H\
HYG File - ID = work pad.hyg - SF 15 PHS 1&2 100
Tc = .1500 hrs
Drainage Area = 47.600 acres Runoff CN= 86
Calc.Increment = .02000 hrs Out.I ncr.= .0 500 hrs
HYG Volume = 22.698 ac-ft
HY DROGRAPH ORDIN ATES (cfs )
Time Ou tput Time incr ement = . 0500 hrs
hrs Time on left represents tim e for fir st value in eac h row.
--------- I
3.4000 -----------------
.00 --------------
.00 ---------
.01 --------
.02 ------- -------
.04
3.6500 .06 .08 .10 .13 .15
3.9000 .18 .21 .23 .26 .28
4.1500 .31 .33 .36 .38 .40
4.4000 .43 .45 .48 .50 .52
4.6500 .55 .57 .59 .61 .64
4.9000 .66 .68 .70 .72 .74
5.1500 .76 .78 .81 .83 .85
5.4000 .87 .89 .91 .93 .95
5.6500 .97 .99 1.00 1.02 1.04
5.9000 1.06 1.08 1.10 1.20 1.40
6.1500 1.63 1.84 2.03 2.20 2.34
6.4000 2.47 2.57 2.64 2.70 2.76
6.6500 2.82 2.88 2.94 3.00 3.05
6.9000 3.11 3.16 3.21 3.27 3.32
7.1500 3.37 3.42 3.47 3.51 3.56
7.4000 I 3.61 3.66 3.70 3.75 3.80
7.6500 3.84 3.89 3.93 3.97 4.01
7.9000 I 4.06 4.10 4.14 4.18 4.22
8.1500 4.26 4.29 4.33 4.37 4.41
8.4000 4.45 4.48 4.52 4.56 4.59
8.6500 I 4.62 4.66 4.69 4.72 4.76
8.9000 I 4.79 4.82 4.86 5.12 5.69
9.1500 6.30 6.85 7.33 7.75 8.08
9.4000 8.35 8.54 8.65 8.72 8.80
9.6500 I 8.87 8.93 9.00 9.07 9.14
9.9000 9.20 9.26 9.33 9.39 9.44
10.1500 9.50 9.56 9.62 9.67 9.73
10.4000 9.78 9.83 9.89 10.48 11.79
10.6500 I 13.20 14.47 15.56 16.48 17.22
SIN: Bentley Systems, Inc.
Bentley PondPack (10.00.027.00) 9:47 AM 7/2/2008
Type.... Unit Hyd. (HYG output) Page 5.19
Name .... SF 15 PHS 1&2 Tag: 100 Event: 100 yr
File.... K:\05\05- 260\05261.19-Wendell Falls - SF 15 Phase 1\11-H\BMP15.1 Wet Pond.ppw
Storm... RDU NOAH 100yr Tag: 100
HYDROGRAPH ORDINATES (cfs)
Time Output Time increment = .0500 hrs
hrs
--------- I- Time on
----------- left represent
-------------- s time for
---------- first value in
---------------- each row.
----------
10.9000 17.80 18.20 18.43 18.56 18.68
11.1500 18.80 18.92 19.03 19.14 19.24
11.4000 19.34 19.45 19.56 22.78 30.12
11.6500 38.17 45.35 51.77 60.86 74.48
11.9000 88.19 101_"77 118.49 149.59 193.48
12.1500 220.74 224.59 216.85 200.12 176.81
12.4000 152.29 129.40 108.91 89.60 72.05
12.6500 57.92 47.41 39.83 34.18 29.85
12.9000 26.69 24.83 24.16 24.17 24.19
13.1500 ) 24.20 24.22 24.23 24.24 24.24
13.4000 24.25 24.26 24.27 23.54 21.85
13.6500 20.01 18.40 17.06 15.95 15.08
13.9000 14.46 14.09 13.96 13.96 13.96
14.1500 13.97 13.97 13.97 13.98 13.99
14.4000 13.99 13.99 13.99 14.00 14.00
14.6500 14.00 14.00 14.00 14.00 14.01
14.9000 14.01 14.01 14.02 13.63 12.73
15.1500 11.76 10.91 10.19 9.60 9.14
15.4000 8.81 8.62 8.54 8.54 8.55
15.6500 8.55 8.55 8.55 8.56 8.56
15.9000 I 8.56 8.56 8.56 8.56 8.56
16.1500 8.56 8.56 8.56 8.56 8.56
16.4000 8.56 8.56 8.56 8.57 8.58
16.6500 8.58 8.57 8.57 8.58 8.57
16.9000 8.57 8.58 8.57 8.57 8.58
17.1500 8.58 8.57 8.58 8.58 8.59
17.4000 8.59 8.59 8.59 8.59 8.59
17.6500 I 8.59 8.59 8.59 8.59 8.59
17.9000 8.59 8.59 8.59 8.30 7.62
18.1500 6.88 6.24 5.70 5.25 4.90
18.4000 4.65 4.51 4.45 4.45 4.45
18.6500 4.45 4.45 4.45 4.46 4.46
18.9000 4.46 4.46 4.46 4.46 4.46
19.1500 I 4.45 4.46 4.45 4.45 4.46
19.4000 I 4.46 4.45 4.45 4.46 4.47
19.6500 I 4.46 4.46 4.46 4.46 4.46
19.9000 4.46 4.46 4.46 4.46 4.46
20.1500 4.46 4.46 4.46 4.46 4.47
20.4000 4.47 4.46 4.46 4.47 4.46
20.6500 I 4.46 4.46 4.46 4.46 4.46
20.9000 I 4.46 4.46 4.46 4.47 4.47
21.1500 I 4.47 4.47 4.47 4.47 4.46
21.4000 I 4.46 4.47 4.46 4.46 4.47
21.6500 I 4.46 4.46 4.46 4.47 4.47
21.9000 I 4.47 4.47 4.47 4.47 4.47
SIN:
Bentley PondPack (10.00.027.00)
9:47 AM
Bentley Systems, Inc.
7/2/2008
Type.... Unit Hyd. (HYG output) Page 5.20
Name.... SF 15 PHS 1&2 Tag: 100 Event: 100 yr
File.... K:A05\05-260\05261.19-Wendell Falls - SF 15 Phase 1\H-H\BMP15.1 Wet Pond.ppw
Storm... RDU NOAA 100yr Tag: 100
HYDROGRAPH ORDINATES (cfs)
Time I Output Time increment = .0500 hrs
hrs I
--------- I- Time on
----------- left represents
--------------- time for
---------- first value
---------- in each row.

22.1500 1
4.47
4.47
4.4'7 --
4.46 -------------
4.47
22.4000 1 4.47 4.46 4.47 4.47 4.48
22.6500 1 4.48 4.47 4.47 4.47 4.47
22.9000 1 4.47 4.47 4.47 4.47 4.47
23.1500 1 4.47 4.47 4.47 4.48 4.48
23.4000 1 4.48 4.48 4.48 4.48 4.47
23.6500 1 4.47 4.47 4.47 4.47 4.47
23.9000 1 4.47 4.47 4.47 4.15 3.41
24.1500 ( 2.62 1.93 1.34 .86 .49
24.4000 1 .22 .06 .00
SIN: Bentley Systems, Inc.
Bentley PondPack (10.00.027.00) 9:47 AM 7/2/2008
Type.... Vol: Elev-Area
Name.... POND 10
Page 6.01
File.... K: \05\05-260\05261 .19-[,Jendell Falls - :?F 15 Phase 1\H-H\BMP15.I Wet Pond.ppw
Elevation Planimeter Area Al+A2+sgr(AI*A2) Volume Volume Sum
(ft)
------------ (sq.in) (sq.ft)
--------------------- (sq.ft)
---------------- (ac-ft)
---------- (ac-ft)
-------------
209.50 33600 0 .000 .000
210.00 37669 106845 .409 .409
211.00 45890 125136 .958 1.366
212.00 -- -- 50392 144370 1.105 2.471
213.00 54392 157138 1.202 3.674
213.50 56781 166747 .638 4.312
POND VOLUME EQUATIONS
* Incremental volume computed by the Conic Method for Reservoir Volumes.
Volume = (1/3) * (EL2-ELl) * (Areal + Area2 + sq.rt.(Areal*Area2))
where: ELI, EL2 - Lower and upper elevations of the increment
Areal,Area2 = Areas computed for ELl, EL2, respectively
Volume = Incremental volume between ELI and EL2
S/N: Bentley Systems, Inc.
Bentley PondPack (10.00.027.00) 9:47 AM 7/2/2008
Type.... Outlet Input Data
[dame.... Outlet 1
Page 7.01
File.... K:A05\05-260\05261.19-Wendel1 Falls - SF 15 Phase 1\H-H\BMP15.1 Wet Pond.ppw
REQUESTED POND WS ELEVATIONS:
Min. Elev.= 209.50 ft
Increment = .50 ft
Max. Elev.= 213.50 ft
OUTLET CONNECTIVITY
---> Forward Flow Only (UpStream to DnStream)
<--- Reverse Flow Only (DnStream to UpStream)
<---> Forward and Reverse Both Allowed
Structure No. Outfall E1, ft E2, ft
-----------------
Inlet Box ----
RO -------
---> CO ---------
211.350 ---------
213.500
Orifice-Circular Ol ---> CO 209.500 213.500
Culvert-Circular CO ---> TW 202.000 213.500
Weir-Rectangular WO ---> TW 212.500 213.500
TW SETUP, DS Channel
SIN: Bentley Systems, Inc.
Bentley PondPack (10.00.027.00) 9:47 AM 7/2/2008
Type.... Outlet Input Data
Name.... Outlet 1
Page 7.02
F.ile.... K:A05\05-260\05261.19-Wendell Falls - SF 15 Phase 1\H-H\BMP15.1 Wet Pond. pp,,,,
OUTLET STRUCTURE I?dPUT DATA
Structure ID - RO
Structure Type = Inlet Box
------------------
# of Openings -----------
- 1 -------
Invert Elev. - 211.35 ft
Orifice Area - 100.0000 sq.ft
Orifice Coeff. .600
Weir Length - 40.00 ft
Weir Coeff. - 3.100
K, Reverse = 1.000
Manninas n .0000
Kev,Charged Riser _ .000
Weir Submergence - No
Structure ID 01
Structure Type - Orifice-Circular
------------------------------------
# of Openings - 1
Invert Elev. 209.50 ft
Diameter - .3300 ft
Orifice Coeff. _ .600
SIN: Bentley Systems, Inc.
Bentley PondPack (10.00.027.00) 9:47 AM 7/2/2008
Type.... Outlet Input Data
Name.... Outlet 1
Page 7.03
File.... K:A05\05-260\05261.19-Wendell Falls - SF 1.5 Phase 1\H-H\BMP15.1 Wet Pond.ppw
OUTLET STRUCTURE INPUT DATA
Structure ID = CO
Structure Type = Culvert-Circular
------------------
No. Barrels ------------
- 1 ------
Barrel Diameter - 4.5000 ft
Upstream Invert - 202.00 ft
Dnstream Invert = 201.00 ft
Horiz. Length = 62.00 ft
Barrel Length - 62.01 ft
Barrel Slope = .01613 ft/ft
OUTLET CONTROL DATA...
Mannings n - .0130
Ke - .9000
Kb - .004209
Kr - .9000
HW Convergence - .001.
(forward entrance loss)
(per ft of full flow)
(reverse entrance loss)
+/- ft
INLET CONTROL DATA...
Equati on form = 1
Inlet Control K = .0340
Inlet Control M = 1.5000
Inlet Control c = .05530
Inlet Control Y = .5400
TI ratio (HW/D) = 1.255
T2 rat io (HW/D) = 1.417
Slope Factor = -.500
Use unsubmerged inlet control Form 1 equ. below TI 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 = 207.65 ft ---> Flow = 118.08 cfs
At T2 Elev = 208.38 ft ---> Flow = 134.95 cfs
SIN: Bentley Systems, Inc.
Bentley PondPack (10.00.027.00) 9:47 AM 7/2/2008
Type.... Outlet Input Data
Name.... Outlet 1
Page 7.04
File.... K:A05\05-260\05261.L°-Wendell Falls - SF 15 Phase 1\H-H\BMP15.1 1%let Pond.ppw
OUTLET STRUCTURE INPUT DATA
Structure ID - WO
Structure Type = Weir-Rectangular
-------------------- ---------------
4 of Openings - 1
Crest Elev. - 212.50 ft
Weir Length = 60.00 ft
Weir Coeff. _ .310000
Weir TW effects (Use adjustment equation)
Structure ID = TW
Structure Type = Ti,J SETUP, DS Channel
------------------------------------
FREE OUTFALL CONDITIONS SPECIFIED
CONVERGENCE TOLERANCES ...
Maxi mum Iteraticns= 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
SIN: Bentley Systems, Inc.
Bentley PondPack (10.00.027.00) 9:47 AM 7/2/2008
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Type.... Individual Outlet Curves
Name.... Outlet 1
File.... K:A05\05-260\05261.19-Wendell Falls - SF 15 Phase 1\H-H\BMP15.1 Wet Por,d.ppw
RATING TABLE FOR ONE OUTLET TYPE
Structure
---------- ID = RO
- (Inlet Box)

Upstream -------------------
ID = (Pond Water --------
Surface)
DNstream ID = CO (Culvert-C ircular)
Pond WS. Device (into) Converge Next DS HGL Q SUM DS C han. TW
Elev. Q HW HGL DS HGL IS HGL Error E rror TW Error
ft
-------- cfs
------- ft
- ------- ft ft +/-ft +/ -cfs ft +/-ft

209.50
.00
... --------
... -------
... ------ -- ----
... ----
Free --- ---- -
Outfall
WS below an invert; no flow.
210.00 .00 ... ... ... Free Outfall
WS below an invert; no flow.
210.50 .00 ... ... ... ... ... Free Outfall
WS below an invert; no flow.
211.00 .00 ... ... ... Free Outfall
WS below an invert; no flow.
211.35 .00 ... ... ._. ... Free Outfall
WS below an invert; no flow.
211.50 7.20 211.50 Free 203.30 .000 .000 Free Outfall
Weir: H = .15ft
212.00 64.98 212.00 Free 206.14 .000 .000 Free Outfall
Weir: H = .65ft
212.50 152.92 212.50 Free 209.55 .000 .000 Free Outfall
Weir: H = 1.15ft
213.00 * 213.00 213.00 213.00 .000 .000 Free Outfall
FULLY CHA RGED RISER: ADJUSTED TO WEIR: H = 1.65ft
213.50 213.50 213.50 213.50 .000 .000 Free Outfall
FULLY CHA RGED RISER: ADJUSTED TO WEIR: H =2.15ft
Page 7.05
SIN:
Bentley PondPack (10.00.027.00)
9:47 AM
Bentley Systems, Inc.
7/2/2008
Type.... Individual Outlet Curves
Name.... Outlet 1
Page 7.06
File.... K:A05\05-260\05261.19-Wendell Falls - SF 15 Phase 1\H-H\BMP15.1 Wet_ Pond.ppw
RATING TABLE FOR ONE OUTLET TYPE
Structure
-- ID = 01 (Orifice- Circular)
------ -
Upstream ----------
ID = ( ---------
Pond Wate ---------
r Surface)
DNstream ID = CO (Culvert- Circular)
Pond WS. Device (into) Converge Next DS HGL Q SUM DS C han. TW
Elev. Q HW HGL DS HGL DS HGL Error Error I'W Error
ft
-------- cfs
------- ft
- ------- ft
------- ft +/-ft + /-cfs ft +/-ft

209.50
.00
... -
... -------
... ------ - -----
... -----
Free -- -------
Out all
WS below an invert; no flow.
210.00 .24 210.00 Free 202.22 .000 .000 Free Outfall_
H =.34
210.50 .38 210.50 Free 202.28 .000 .000 Free Outfall
H =.84
211.00 .48 211.00 Free 202.31 .000 .000 Free Outfall
H =1.34
211.35 .53 211.35 Free 202.33 .000 .000 Free Outfall
H -1.69
211.50 .56 211.50 Free 203.30 .000 .000 Free Outfall
H -1.84
212.00 .63 212.00 Free 206.14 .000 .000 Free Outfall
H =2.34
212.50 .69 212.50 209.55 209.55 .000 .000 Free Outfall
H =2.84
213.00 213.00 213.00 213.00 .000 .000 Free Outfall
FLOW PREC EDENCE SET TO DOWNS TREAM CON TROLLI NG STRUCTURE
213.50 213.50 213.50 213.50 .000 .000 Free Outfall
FLOW PRECEDENCE SET TO DOWNS TREAM CON TROLLING STRUCTURE
S/N:
Bentley PondPack (10.00.027.00)
9:47 AM
Bentley Systems, Inc.
7/2/2008
•
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Type.... Individual Outlet Curves
Name.... Outlet 1
File.... K:A05\05-260\05261.19-Wendell Falls - SF 15 Phase 1\H-H\BMP15.I Wet Pond.ppw
RATING TABLE FOR ONE OUTLET TYPE
Structure ID = CO (Culvert-Circular)
--------------------------------------
Mannings open channel maximum capacity: 268.64 cfs
UPstream ID's= R0, Ol
DNstream ID - TW (Pond Outfall)
Pond WS. Device (into) Converge Next DS HGL Q SUM DS Chan. TW
Elev. Q HW HGL DS HGL DS HGL Err or Error TW Error
ft
--------- cfs
------- ft
- ------- ft It +/- ft +/-cfs ft +/-ft

209.50
.00
... --------
... ------- ---
... . ---
.. ------
... ------- -------
Free Outfa.tl
WS below a n invert; no flow.
210.00 .24 202.22 Free Free .000 .001 Free Outfall
CRIT.DEPTH CONTROL Vh= .045ft Dcr= .135ft CRIT.DEPTH Hev= .OOft
210.50 .38 202.28 Free Free .000 .000 Free Outfail
CRIT.DEPTH CONTROL Vh= .057ft Dcr= I7Ift CRIT.DEPTH Hev- .OOft
211.00 .48 202.31 Free Free .000 .000 Free Outfall
CRIT.DEPTH CONTROL Vh= .064ft Dcr= .191ft CRIT.DEPTH Hev= .OOft
211.35 .53 202.33 Free Free .000 .000 Free Outfall
CRIT.DEPTH CONTROL Vh= .068ft Dcr= .203ft CRIT.DEPTH Hev= .OOft
211.50 7.77 203.30 Free Free .000 .006 Free Outfall
CRIT.DEPTH CONTROL Vh= .272ft Dcr= .784ft CRIT.DEPTH Hev= .OOft
212.00 65.63 206.14 Free Free .000 .019 Free Outfall
CRIT.DEPTH CONTROL Vh= .939ft Dcr= 2.359ft CRIT.DEPTH Hev= .OOft
212.50 153.61 209.55 Free Free .000 .000 Free Outfall.
INLET CONT ROL... S ubmerged: HW -7. 55
213.00 198.41 213.00 Free Free .000 64.400 Free Outfall
INLET CONT ROL... S ubmerged: HW =11 .00
213.50 204.09 213.50 Free Free .000 186.824 Free Outfall
INLET CONTROL... S ubmerged: HW =11 .50
Page 7.07
S/N:
Bentley PondPack (10.00.027.00)
9:47 AM
Bentley Systems, Inc.
7/2/2008
Type.... Individual Outlet Curves
Name.... Outlet 1
Page 7.08
File.... K:\05\05-260\05261.19-Wendell Falls - SF 15 Phase 1\H-H\BMP15.1 Wet Pond.ppw
RATING TABLE FOR ONE OUTLET TYPE
Structure ID = WO (Weir-Rectangular)
--------------------------------------
Upstream ID = (Pond Water Surface)
DNstream ID = TW (Pond Outfall)
WS Elev,De vice Q Tail Water Notes
----------
WS Elev. ------
Q ---------------
TW Elev Converge --- -----------------------
ft
-------- - cfs
------ ft +/-ft
-------- ----- Co
--- mputation [Messages
-----------------------
205.50 .00 Free Outfall
WS below an invert; no flow.
210.00 .00 Free Outfall
WS below an invert; no flow.
210.50 .00 Free Outfall
WS below an invert; no flow.
211.00 .00 Free Outfall
WS below an invert; no flow.
211.35 .00 Free Outfall
WS below an invert; no flow.
211.50 .00 Free Outfall
WS below an invert; no flow.
212.00 .00 Free Outfall
WS below an invert; no flow.
212.50 .00 Free Outfall
WS below an invert; no flow.
213.00 6.58 Free Outfall
H= .50; Htw=.00; Qfree= 6.58;
213.50 18.60 Free Outfall
H= 1.00; Htw=.00; Qfree =18.60;
SIN: Bentley Systems, Inc.
Bentley PondPack (10.00.027.00) 9:47 AM 7/2/2008
Type.... Composite Rating Curve
Name.... Outlet 1
Page 7.09
File.... K:A05\05-260\05261.19-Wendell Falls - SF 15 Phase 1\H-H\BMP15.1 Wet Pond.ppw
***** COMPOSITE OUTFLOW SUMMARY ****
WS Elev, Total Q
Elev. Q
ft cfs
209.50 .00
210.00 .24
210.50 .38
211.00 .48
211._.-' .53
211.50 7.77
212.00 65.63
212.50 153.61
213.00 204.99
213.50 222.69
Notes
- Converge ---------- --- --
TW E lev Error
ft +/-ft
-------- ----- Contributing
------- Structures

Free
Outfall ----
(no Q: R0 ---
,O1 ------- ----
,C0,W0)
Free Outfall 01,CO (no Q: RO,WO)
Free Outfal_l O1,C0 (no Q: RO,WO)
Free Outfall 01,CO (no Q: RO,WO)
Free Outfall 01,CO (no Q: RO,WO)
Free Outfall R0,01,C0 (no Q: WO)
Free Outfall RO,01,CO (no Q: WC))
Free Outfall R0,01,C0 (no Q: WO)
Free Outfall RO,CO,WO (no Q: 01)
Free Outfall_ RO,CO,WO (no Q: 01)
SIN: Bentley Systems, Inc.
Bentley PondPack (10.00.027.00) 9:47 AM 7/2/2008
Appendix A
Index cf Starting Page Numbers for ID Names
----- 0
Outlet 1... 7.01, 7.05, 7.09
----- P -----
POND 10... 6.01
PRE... 3.01, 4.01, 5.01, 5.02, 5.04,
5.05, 5.07, 5.08
----- S -----
SF 15 PHS 1&2... 3.03, 4.02, 5.10,
5.11, 5.13, 5.14, 5.17, 5.18
W
Watershed... 1.01, 2.01, 2.02, 2.03,
2.04, 2.05, 2.06
A-1
SIN :
Bentley PondPack (10.00.027.00)
9:47 AM
Bentley Systems, Inc.
7/2/2008

Project Name: Wendell Falls, SF-15 Phase 1 & 2
City/State: WENDELL, NC
Overall
Total Drainage Area = 47.60 ac
Impervious Surfaces = 17.82 ac
Streets = 231,180 sf
Sidewalks = 68,921 sf
Lots = 476,000 sf
Undisturbed & Managed Open Space = 29.78 ac
% Impervious Surface Area = 37.4 %
Project #: 205261.19
Date: 2-Jul-08
1-Inch Runoff Volume Calculation
Using the runoff volume calculations in the "Simple Method" as described by Schueler (1987)
Rv = 0.05 + 0.009(1) where,
Rv = Runoff coefficient, in./in.
Rv = 0.39 in./in. I = Percent impervious
Total runoff volume from 1-inch precipitation:
Runoff volume, S = (Design rainfall) (Rv) (Drainage Area)
S = 1.535 acre-ft
66847 cu. ft.
BMP Sizing Phase 1 & 2.x1s - BMP Sizing
7/2/2008
Project Name: Wendell Falls, SF-15 Phase 1
City/State: Wendell, NC
STORMWATER BMP -Wet Detention Pond
BMP 15.1
Orifice Calculator
Q =Cd*A*(2gh)"(1/2)
Variables
WQ Volume: 1.535 Acre-ft 66864.6 cf
Head: 0.5 ft 0.25 ft
Draw down time: 96 hrs 345600s
Orifice Area = 0.080363 sq. ft 11.57233 sq. in
Orifice Diameter = 3.838536 in
USE 4 In DIAMETER ORIFICE
Actual Diameter = 0.087266 sq ft
Crest Elevation = 203.00 msl
Orifice Elevation = 202.00 msl
Head = 0.83 ft
Flow = 0.38 cfs
Project #: 205260.19
Date: 2-j u 1-08
Constants
9 = 32.2 ft/s2
Cd= 0.6
GRASSED SWALE
CALCULATIONS
AND
WORKSHEETS
Wendell Falls Subdivision W&R Project 20526i.ig
SF 15 Phase 1 Stormwater Management Report July 2oo8
Permit No:
(to be assigned by DWQ)
Jill, REQUIRED ITEMS CHECKLIST
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.
Initials Pagel Plan
Sheet No.
UJ
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),
- Swale dimensions (width, length, depth),
Maintenance access,
- Proposed drainage easement and public right of way (ROW),
- Grass species, and
Boundaries of drainage easement.
1 5 LJI-3 "
'
2. Plan details (1
= 50
or larger) for the grassed Swale showing:
- Swale dimensions (width, length, depth),
- Maintenance access,
- Proposed drainage easement and public right of way (ROW),
- Design at ultimate build-out,
- Grass species,
- Off-site drainage (if applicable),and
- Boundaries of drainage easement.
W '3 3. Section view of the grassed Swale (1" = 20' or larger) showing:
- Side slopes,
- Longitudinal slope,
- Freeboard
- Swale dimensions, and

1
L - SHWT level(s)
c7U? 4. Supporting calculations (including maximum velocity calculations for applicable storms)
;7
4 (AIL 5. A copy of the signed and notarized operation and maintenance (0&M) agreement.
A 6. A copy of the deed restrictions (if required).
SW401-Grassed Swale-Rev.3 Part III, Page 1 of 1
Permit Number:
(to be provided by DWQ)
T15W OF W A TF9
NCDENR °
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
401 CERTIFICATION APPLICATION FORM
GRASSED SWALE SUPPLEMENT
This form must be filled out, printed and submitted.
The Required Items Checklist (Part Ill) must also be filled out, printed and submitted along with all of the required information.
L PROJECT INFORMATION
Project name Wendell Falls Subdivision SF 15 Phase 1
Contact name Ken Jesneck, PE
Phone number 919-469-3340
Date July 2, 2008
Drainage area number BMP 15.1
11. DESIGN INFORMATION
Site Characteristics
Drainage area 47.60 ft2
Impervious area 17.82 ft
Percent impervious 37.4%%
Design rainfall depth 1.00 inch
Peak Flow Calculations
10-yr storm runoff depth 3.60 in
10-yr storm intensity 7.22 in/hr
Post-development 10-yr storm peak flow 169.12 ft3/sec
Velocity
Maximum non-erosive velocity (peak 10-year storm) 4.50 ft/sec
Soil characteristics (enter "x" below)
Sand/silt (easily erodible) X
Clay mix (erosion resistant)
Grass Type (enter "x" below)
Bermuda
Tall fescue X
Bahiagrass
Kentucky bluegrass
Grass-legume mixture
Swale type: Fill out one of the options below:
Option 1: Curb Outlet Swale: (Y or N)
Maximum velocity
Side slopes :1
Swale length ft
Option 2: Conveyance Swale. Seekino Pollutant Credit: Y (Y or N)
Maximum velocity for 10-yr storm 1.00 ft/sec OK
Side slopes 5.00 :1 OK
Swale length 150.00 ft OK
Form SW401-Grassed Swale-Rev.3 Parts I and II. Project Design Summary, Page 1 of 2
Permit Number:
(to be provided by DWQ)
Swale Characteristics
Swale Shape: Enter an "x' in the appropriate cell below:
Trapezoidal X
Parabolic
V-shaped
Width of the bottom of the swale 27.00 ft
Width of the top of the swale 57.00 ft
Additional Information
Is the swale sized for all runoff from ultimate build-out? Y (Y or N) Insufficient sizing
Is the BMP located in a proposed drainage easement with a
Y (Y or N)
Insufficient ROW location.
recorded access easement to a public Right of Way (ROW)?
What is the distance from the bottom of the swale to the SHWT? 1.00 ft OK
What is the ground level elevation? 211.00 fmsl
What is the elevation of the bottom of the swale? 211.00 fmsl
What is the SHWT elevation? 210.00 fmsl
What is the longitudinal slope of the swale? 0.50% OK
What is the depth of freeboard? 1.00 ft OK
Form SW401-Grassed Swale-Rev.3 Parts I and II. Project Design Summary, Page 2 of 2
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•
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•
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Grassed Swale-10yr 24hr
Project Description
Friction Method Manning Formula
Solve For Normal Depth
Input Data
Roughness Coefficient 0.035
Channel Slope 0.00500 ft/ft
Left Side Slope 5.00 ft/ft (H:V)
Right Side Slope 5.00 ft/ft (H:V)
Bottom Width 27.00 ft
Discharge 5.21 ft3/s
Results
Normal Depth 0.19 ft
Flow Area 5.35 ftZ
Wetted Perimeter 28.95 ft
Top Width 28.91 ft
Critical Depth 0.10 ft
Critical Slope 0.03821 ft/ft
Velocity 0.97 ft/s
Velocity Head 0.01 ft
Specific Energy 0.21 It
Froude Number 0.40
Flow Type Subcritical
GVF Input Data
Downstream Depth 0.00 ft
Length 0.00 It
Number Of Steps 0
GVF Output Data
Upstream Depth 0.00 It
Profile Description
Profile Headloss 0.00 ft
Downstream Velocity Infinity ft/s
Upstream Velocity Infinity ft/s
Normal Depth 0.19 ft
Critical Depth 0.10 ft
Channel Slope 0.00500 ft/ft
Critical Slope 0.03821 ft/ft
Bentley Systems, Inc. Haestad Methods Solution Center Bentley FlowMaster [08.01.071.00)
7/2/2008 11:14:27 AM 27 Siemons Company Drive Suite 200 W Watertown, CT 06795 USA t1-203-755-1666 Page 1 of 1
Grassed Swale-Peak Storm
Project Description
Friction Method Manning Formula
Solve For Normal Depth
Input Data
Roughness Coefficient 0.035
Channel Slope 0.00500 f tft
Left Side Slope 5.00 ft/ft (H:V)
Right Side Slope 5.00 ft/ft (H:V)
Bottom Width 27.00 ft
Discharge 169.12 ft3/s
Results
Normal Depth 1.46 ft
Flow Area 50.04 ft2
Wetted Perimeter 41.88 ft
Top Width 41.59 ft
Critical Depth 1.00 ft
Critical Slope 0.01886 ft /ft
Velocity 3.38 ft /s
Velocity Head 0.18 ft
Specific Energy 1.64 ft
Froude Number 0.54
Flow Type Subcritical
GVF Input Data
Downstream Depth 0.00 ft
Length 0.00 ft
Number Of Steps 0
GVF Output Data
Upstream Depth 0.00 ft
Profile Description
Profile Headloss 0.00 ft
Downstream Velocity Infinity ft/s
Upstream Velocity Infinity ft/s
Normal Depth 1.46 ft
Critical Depth 1.00 ft
Channel Slope 0.00500 ft/ft
Critical Slope 0.01886 ft/ft
Bentley Systems, Inc. Haestad Methods Solution Center Bentley FlowMaster [08.01.071.00]
71212008 11:14:39 AM 27 Siemons Company Drive Suite 200 W Watertown, CT 06795 USA [phone] Page 1 of 1
FLOTATION AND ANTI-SEEP
CALCULATIONS
Wendell Falls Subdivision W&R Project 20526i.ig
SF 15 Phase i Stormwater Management Report July 2008
Flotation Calculations
Project No: 02050261.19 Calc. By: KLJ
Project Name: Wendell Falls - SF-15 BMP 15.1 Date: July 2, 2008
Components Weights
Wgt. H2O Wgt.Concrete Wgt. Soil (Sat)
(Ibs/cu. ft.) (Ibs/cu. ft.) (Ibs/cu. ft.)
62.40 150.00 120.00
Outlet Structure
Base Length Width Thickness
(ft) (ft) (i n)
10.00 10.00 0.00
Walls Length Width Wall Height Thickness
(ft) (ft) (ft) (ft)
10.00 10.00 9.35 0.50
Fillet Volume
(cu. ft)
0.00
Weight of Wetwell = (Outside Vol ume - Inside Volume + Fillet Vol ume) x Weight of Concrete
Walls Base Fillet Total
Weight 29,452.50 0.00 0.00 29,452.50 (Ibs)
Soil
Soil Weight = ((Base Area - Wetwell OD Area) x Height of Soil) x Weight of Soil
Total Height 2.00 (ft)
Weight 18,849.56 (Ibs)
Bottom Slab
Circular
Diameter Thickness
(ft) (in) Total
0.00 0.00 0.00 (Ibs)
Rectangular
Width of slab Length of slab Thickness
(ft) (ft) (in) Total
14.00 14.00 24.00 58,800.00 (Ibs)
Withers and Ravenel, Inc. Page 1 of 2
Flotation Calculations
Project No: 02050261.19 Calc. By: KLJ
Project Name: Wendell Falls - SF-15 BMP 15.1 Date: Jul 2, 2008
Hatch O enin s
Circular
Diameter
(in) Total
1 0.00 (Ibs)
2 0.00 (Ibs)
3 0.00 (Ibs)
Rectangular
Length Width
(in) (in) Total
1 0.00 0.00 0.00 (Ibs)
2 0.00 (Ibs)
3 0.00 (Ibs)
Upward Actin Force
Upward Force Act ing on Bottom of Stru cture = Base Area x Height of Water x Weight of Water
Total Height 11.35 (ft)
Buoyancy Force 85,697.04 (Ibs)
Factor of Safe
Factor of Safety = Downward Force of Structure and Soil/Upward Force of Water
Total Downward Force 107,102.06 (Ibs)
Total Buoyancy Force 85,697.04 (Ibs)
Factor of Safety= 1.25
Withers and Ravenel, Inc. Page 2 of 2
OPERATION AND MAINTENANCE
AGREEMENTS
Wendell Falls Subdivision W&R Project 20526i.ig
SF 15 Phase i Stormwater Management Report July 2oo8
Permit Name:
(to be provided by DWQ)
Drainage Area Number:
Grassed Swale 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:
- The drainage area of the grassed swale will be carefully managed to reduce the
sediment load to the grassed swale.
- After the first-time fertilization to establish the grass in the swale, fertilizer will
not be applied to the grassed swale.
The grassed swale will be inspected once a quarter. 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 length of the Trash/debris is present. Remove the trash/ debris.
swale
Areas of bare soil and/or Regrade the soil if necessary to
erosive gullies have formed. remove the gully, and then re-sod
(or plant with other appropriate
species) and water until established.
Provide lime and a one-time
fertilizer application.
Sediment covers the grass at Remove sediment and dispose in an
the bottom of the swale. area that will not impact streams or
BMPs. Re-sod if necessary.
Vegetation is too short or too Maintain vegetation at a height of
long. approximately six inches.
The receiving water Erosion or other signs of Contact the NC Division of Water
damage have occurred at the Quality 401 Oversight Unit at 919-
outlet. 733-1786.
Form SW401-Grassed Swale O&M-Rev.3 Page 1 of 2
Permit Number:
(to be proi,ldc d by DWQ)
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 name:Wendell Falls SF 15 Phase 1
BMP drainage area number:BMP 15.1
Print name:Michael L. Jones
Title:
Address:5660 Six Forks Road Raleigh North Carolina 27609
Phone:
Signatl
Date:- 6 4 o v o
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.
I, ?WNU-?-s la . -4vwAel, , a Notary Public for the State of
r OQTk4 - C 94a -Lkn?? , County of 'Wks , do hereby certify that
M, C A.SL L. 1 nNGs personally appeared before me this 2 3OPL-
day of JUNE , W08 , and acknowledge the due execution of the
forgoing grassed swale maintenance requirements. Witness my hand and official seal,
PHYUIS A. HOWARD
Notary Public. North Carolina
Franklin County
My Commission Expires
May 09, 2012
SEAL
My commission expires MAt 09,20?2
Form SW401-Grassed Swale O&M-Rev.3 Page 2 of 2
Permit Number:
(to be provided by DWQ)
Drainage Area Number:
Wet Detention Basin 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.
The wet detention basin system is defined as the wet detention basin,
pretreatment including forebays and the vegetated filter if one is provided.
This system (check one):
® does ? does not incorporate a vegetated filter at the outlet.
This system (check one):
® does ? does not incorporate pretreatment other than a forebay.
Important maintenance procedures:
- Immediately after the wet detention basin is established, the plants on the
vegetated shelf and perimeter of the basin should be watered twice weekly if
needed, until the plants become established (commonly six weeks).
- No portion of the wet detention pond should be fertilized after the first initial
fertilization that is required to establish the plants on the vegetated shelf.
- Stable groundcover should be maintained in the drainage area to reduce the
sediment load to the wet detention basin.
- If the basin must be drained for an emergency or to perform maintenance, the
flushing of sediment through the emergency drain should be minimized to the
maximum extent practical.
- Once a year, a dam safety expert should inspect the embankment.
After the wet detention pond is established, it should be inspected once a month and
within 24 hours after every storm event greater than 1.0 inches (or 1.5 inches if in a
Coastal County). Records of operation and maintenance should be kept in a known set
location and must 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 BMP Trash/debris is resent. Remove the trash/ debris.
The perimeter of the wet Areas of bare soil and/or Regrade the soil if necessary to
detention basin 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.
Vegetation is too short or too Maintain vegetation at a height of
long. approximately six inches.
Form SW401-Wet Detention Basin O&M-Rev.3 Page 1 of 4
Permit Number:
(to be provided by DWQ)
Drainage Area Number:
BMP element: Potential problem: How I will remediate the problem:
The inlet device: pipe or The pipe is clogged. Unclog the pipe. Dispose of the
swale sediment off-site.
The pipe is cracked or Replace the pipe.
otherwise damaged.
Erosion is occurring in the Regrade the Swale if necessary to
swale. smooth it over and provide erosion
control devices such as reinforced
turf matting or riprap to avoid
future problems with erosion.
The forebay Sediment has accumulated to Search for the source of the
a depth greater than the sediment and remedy the problem if
original design depth for possible. Remove the sediment and
sediment storage. dispose of it in a location where it
will not cause impacts to streams or
the BMP.
Erosion has occurred. Provide additional erosion
protection such as reinforced turf
matting or riprap if needed to
prevent future erosion problems.
Weeds are present. Remove the weeds, preferably by
hand. If pesticide is used, wipe it on
the plants rather than spraying.
The vegetated shelf Best professional practices Prune according to best professional
show that pruning is needed practices
to maintain optimal plant
health.
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 to establish the
ground cover if a soil test indicates
it is necessary.
Weeds are present. Remove the weeds, preferably by
hand. If pesticide is used, wipe it on
the plants rather than spraying.
The main treatment area Sediment has accumulated to Search for the source of the
a depth greater than the sediment and remedy the problem if
original design sediment possible. Remove the sediment and
storage depth. dispose of it in a location where it
will not cause impacts to streams or
the BMP.
Algal growth covers over Consult a professional to remove
50% of the area. and control the algal growth.
Cattails, phragmites or other Remove the plants by wiping them
invasive plants cover 50% of with pesticide (do not spray).
the basin surface.
Form SW401-Wet Detention Basin O&M-Rev.3 Page 2 of 4
Permit Number:
(to be provided by DWQ)
Drainage Area Number:
BMP element: Potential problem: How I will remediate the problem:
The embankment Shrubs have started to grow Remove shrubs immediately.
on the embankment.
Evidence of muskrat or Use traps to remove muskrats and
beaver activity is present. consult a professional to remove
beavers.
A tree has started to grow on Consult a dam safety specialist to
the embankment. remove the tree.
An annual inspection by an Make all needed repairs.
appropriate professional
shows that the embankment
needs repair.
The outlet device Clogging has occurred. Clean out the outlet device. Dispose
of the sediment off-site.
The outlet device is damaged Repair or replace the outlet device.
The receiving water Erosion or other signs of Contact the local NC Division of
damage have occurred at the Water Quality Regional Office, or
outlet. the 401 Oversight Unit at 919-733-
1786.
The measuring device used to determine the sediment elevation shall be such
that it will give an accurate depth reading and not readily penetrate into
accumulated sediments.
When the permanent pool depth reads 1.5 feet in the main pond, the sediment
shall be removed.
When the permanent pool depth reads 1.5 feet in the forebay, the sediment
shall be removed.
BASIN DIAGRAM
(fill in the blanks)
Sediment Removal E. 203.00
Permanent Pool Elevation 209.50
------------- -- Volume
Bottom Elevatio 202.00 -ft Min.
Sediment
Storage
FOREBAY
Pool
\-------------------------------------------- Sediment Removal Elevation 204.00 Volume
------I
Bottom Elevation 203.00 j 1-ft
MAIN POND
Storage
Form SW401-Wet Detention Basin O&M-Rev.3 Page 3 of 4
Permit Number:
(to be Provided by DWQ)
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 name:Wendell Fall Subdivision SF 15 Phase 1
BMP drainage area number:BMP 15.1
Print name:Michael L. Jones
Title:
Address:5660 Six Forks Road Raleigh North Carolina 27609
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.
1, ?t-Iry L.L es &.. 1?rowa.? , a Notary Public for the State of
Notts CAauNA. , County of WA1cE , do hereby certify that
M%CMNC-L L. SoNe% personally appeared before me this 2`0
day of 5ONE , and acknowledge the due execution of the
forgoing wet detention basin maintenance requirements. Witness my hand and official
seal,
PHtllliS A. HOWARD
Notary Public, North Carolina
Franklin County
My Commission Expires
Moy 09, 2012
SEAL
My commission expires Mme{ Oct ,201 Z
Form SW401-Wet Detention Basin O&M-Rev.3 Page 4 Of 4
irate: 0 di U O
WITHERS
Wendell Falls - SF15: Phase 1
November 20, 2007
Revised:
February 8, 2008
March 6, 2008
July 2, 2008
Prepared By
Withers & Ravenel
111 MacKenan Drive
Cary, NC 27511
Project #: 02050261.19
Enzinee
Ken L. Jesneck, P.E.
Designer
John Core, E.I.
C) 6- 110 1-1 V'S
o ?ZIA
?pS
l???N?ffay???
.o
?,.•OFES
e • ?
Applicant
Wendell Falls Residential, LLC
5660 Six Forks Rd.
Suite 202
Raleigh, NC 27609
Attn. Greg Ferguson
P• 919 861 5299
SEAT.
1849?

b
F: 919.861.5277 11 ?-
fF?s
"ll
it?l
111 MacKenan Drive i Cary, North Carolina 27511 1 tel: [phone] fax: [phone]oo8 i www.withersravenel.com
7040 Wrightsville Avenue, Suite 1o1 i Wilmington, North Carolina 28403 1 tel : [phone] fax : [phone]
1027 Sabbath Home Road SW i Supply, NC 28462 1 tel: 9zo-842-9392 i fax: 9zo.842.8o19
RAVEN EL
ENGINEERS I PLANNERS I SURVEYORS
K:\05\05-260\05261.19-Wendell Falls - SF 15 Phase 1\Proj\Calcs\Storm Drainage\Storm Drainage Report - SF15-
PH1.doc
Wendell Falls - SF15: Phase 1
General Descriution:
Wendell Falls - SF 15: Phasel is a 20.47 ac, tract located to the south of Wendell Falls SF-14, with an entrance off
Poole Road. There will be one (1) flared end section directing storm water drainage into a constructed wetland before
being directed into an existing tributary of Lake Myra. Rip rap aprons will be designed to dissipate the velocity at the
outlet point.
Erosion Control:
Erosion control will be handled by a separate submittal to Wake County.
Storm Drainage Methodology:
The storm drainage system consists of a series of structures and pipes to convey storm drainage along the roadway to
multiple outlet points. The outlet structure discharging into the unnamed tributary of Lake Myra after being treated in
BMP 15.1. All pipes with in the right-of-way will be reinforced concrete (RCP) (class III, unless otherwise noted)
and a minimum of 15 inches in diameter inside of right-of-way and 12 inches outside of right-of-way. Pipes outside
of the right-of-way shall be HDPE (smooth interior) unless otherwise noted and a minimum of 10 inches in diameter.
The drainage pipes were sized using a computer program called "StormCAD" by Haestad. "C" coefficients and
drainage areas were determined for each inlet and input into the program. The time of concentration was also entered
for each area. The program uses an established rainfall intensity distribution for the Raleigh-Durham area and
calculates pipe sizes and hydraulic grade lines based on a step backwater analysis.
Storm Drainage
(t0 year storm)
Scenario: 10 -Year Storm
CB 1
CB 1533
Title: Wendell Falls - SF15 Phase 1 Project Engineer: Ken Jesneck
k:\...\proj\calcs\storm drainageVes 1500.stm Withers & Ravenel Engineering StormCAD v5.6 [05.06.014.00]
07/02/08 02:45:160IBentley Systems, Inc. Haestad Methods Solution Center Watertown, CT 06795 USA [phone] Page 1 of 1
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Velocity Dissipaters
Velocity Dissipaters
FES 1500
NRCD Land Quality Section
NYDOT Dissipater Design Results
Pipe diameter (ft) 4.5
Outlet velocity (fps) 12.91
Apron length (ft) 45.00
Minimum Apron Width (ft) 22.50 (W = Dia. + 0.4xLength)
Actual Apron Width (ft) 55.00
AVG DIAM
(inches)
3
6
13
» 23
STONE THICKNESS
CLASS (inches)
A 9
B 22
B or 1 22
2 27«
BMP# 15.1 Outlet
NRCD Land Quality Section
NYDOT Dissipater Design Results
Pipe diameter (ft) 4.5
Outlet velocity (fps) 16.40
Apron length (ft) 45.00
Apron Width (ft) 49.50 (W = Dia. + Length)
AVG DIAM STONE THICKNESS
(inches) CLASS (inches)
3 A 9
6 B 22
13 B or 1 22
» 23 2 27«
Gutter Spread Calculations
Scenario: Spreads
FES 1500
CB
CB 1535
Title: Wendell Falls - SF15 Phase 1 Project Engineer: Ken Jesneck
k:\...\proj\calcs\storm drainage\fes 1500.stm Withers & Ravenel Engineering StormCAD v5.6 [05.06.014.00]
07/02/08 02:50:380gentley Systems, Inc. Haestad Methods Solution Center Watertown, CT 06795 USA [phone] Page 1 of 1
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Appendix
•
•
•
•
•l
•
•
•
Appendices
8.06 ".-TIM Lei I Im M*
Riprap (large stones of various sizes) is often used to prevent erosion at the ends
of culverts and other pipe conduits. It converts high-velocity, concentrated pipe
flow into low-velocity, open channel flow. Stone should be sized and the apron
shaped to protect receiving channels from erosion caused by maximum pipe exit
velocities. Riprap outlet structures should meet all requirements in Practice
Standards and Specifications: 6.41, Outlet Stabilization Structure.
Several methods are available fordesigning riprap outlet structures. The method
presented in this section is adapted from procedures used by the USDA Soil
Conservation Service, Outlet protection is provided by a level apron of sufficient
length and flare to reduce flow velocities to nonerosive levels.
Design Procedure for The following procedure uses two sets of design curves: Figure 8.06a is used
Riprap Outlet for minimum taitwaterconditions and Figure 8.06b for maximum tailwater con
Protection ditions.
Step 1. Determine the tailwater depth from channel characteristics below the
pipe outlet for the design capacity of the pipe. If the tailwater depth is less than
half the outlet pipe diameter, it is classified minimum tailwater condition. If it
is greater than half the pipe diameter, it is classified maximum condition. Pipes
that outlet onto wide flat areas with no defined channel are assumed to have a
minimum tailwater condition unless reliable flood stage elevations show other-
wise-
Step 2. Based on the tailwater conditions determined in step 1, enter Figure
8.06a or Figure 8.06b and determine dso riprap size and minimum apron length
(La). The d5o size is the median stone size in a well-graded riprap apron.
Step 3. Determine apron width at the pipe outlet, the apron shape, and the apron
width at the outlet end from the same figure used in Step 2.
Step 4. Determine the maximum stone diameter:
dmax = 1.5 x d5o
Step S. Determine the apron thickness:
Apron thickness = 1.5 x dmax
Step 6. Fit the riprap apron to thesite by making it level for the minimum length,
La, from Figure 8.06a or Figure 8.06b. Extend the apron farther downstream
and along channel banks until stability is assured. Keep the apron as straight as
possible and align it with the flow of the receiving stream. Make any necessary
alignment bends near the pipe outlet so that the entrance into the receiving
stream is straight.
8.06.1
Rev. 121!3
0
Some locations may require lining of the entire channel cross section to assure
stability.
It maybe necessary to increase the size of riprap where protection of the channel
side slopes is necessary (Appendix 8.05). Where overfalls exist at pipe outlets
or flows are excessive, a lined stilling basin should be considered. Acceptable
design procedures for stilling basins are included in the list of references.

8.06.2
•
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•
•
•
•
• y
•
•
•
•
•
Appendices
Discharge (ft3/sec)
3
m
N
2 C-n
2
N
n.
Cr
0
1 v
0
1000
Curves may not be extrapolated.
Figure 8.06a Design of outlet protection protection from a round pipe flowing full, minimum tailwater condition (T. < 0.5 diameter),
Rev. 12J93
8.06.3
3 5 10 20 50 100 200 500
•

•

•
n

• o
T
Outlet W = Do • 0ALa 120 _
•
diameter ((b)
pig
La ?
•
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0.50a 1 10
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r l t
l I . ,
V 10

3 5 10 20 50 t00 200 5 00 1000
• Discharge (ft3lsec)
•
•
•
• Curves may not be extrapolated.
• Figure 8.06b Design of outlet protection from a round pipe flowing full, maximum tailwater condition (T. ? 0 5 diameter)
•
•

•
•
• 8.06.4 Rev. 12,93
•
•
•
Appendices
NEW YORK DOT DISSIPATOR METHOD
FOR USE IN DEFINED CHANNELS
(Source: "Bank and channel lining procedures", New Yoric Department
of Transportation. Division of Design and Construction, 1971.)
Note: To use the following chart you must know:
(1) Q full capacity
(2) Qto
(3) V full
(4) Vlo
where Q = discharge in cfs and V = Velocity in FPS
ESTIMATION OF STONE SIZE AND DIMENSIONS FOR
CULVERT APRONS
Step t) Compute flow velocity Vo at culvert or paved channel outlet
Step 2) For pipe culverts D. isdiameter.
For pipe arch, arch and box culverts, and paved channel outlets,
Do=Ao, where A.= cross-sectional area of flow at oudet_
For multiple culverts, use Do=1.25xDo of single culvert.
Step 3) For apron grades of 10% or steeper, use recommendations
For next higher zone. (Zones I through 6).
25
20
CL
LL}
U
W 10
5
0
t
?r
?
i
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. . t . ,
1 1 1 , I
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0, 5'
Figure 8.06.b.1
to, is, 20' 25'
DIAMETER (Ft.)
Rev. I7M 8.06.5

z

(AI

1

A" MAN=

STONE FILLING (FINE)
CL
A PROYECT CIAVERf

L1
3 x Do TO PREVENT
SCWR
HOLE USE L2 ALWAYS
L2
4 x De
2 _
_
_
STONE FILLING (LIGHT) CL. B 3 x Oo 6 x Do
3
4 STONE FILLING (MEDIUM) CL 1
STONE FILLING (HEAVY) CL- 1 4 x Do
4 x Do 8 x Do
_8 x Do
5 STONE FILLING (HEAVY) CL 2 5 x Do 10 x Oo
6 STONE FILLING (HEAVY) CL 2 6 x Do 10 x Do
7 SPECIAL STUDY REQUIRED (ENERGY DISSIPATORS. STILLING
BASIN OR LARGER SIZE STONE)
Fig 8.06.b.2
Width = 3 times pipe dia. (min.)
DETERMINATION OF STONE SIXES FOR DUMPED STONE
CHANNEL LININGS AND REVETMENTS
Step 1) Use figure 8.06.b.3 to determine maximum stone size (e.g. for 12
Fps=20" or 550 Ibs_
Step 2) Use figure 8.06.b.4 to determine acceptable size range for stone
(for 12 FPS it is 125-500 Ibs. for 75% of stone, and the maximum
C1-
and minimum range in weight should be 25-500 lbs.)
Note: In determining channel velocities for stone linings and revetment, use
the following coefficients of roughness:
Diameter Mannin's Min. thickness
(inches) "n" of lining _ _ (inches)
Fine 3 0.031 9 12
Light 6 0.035 12 18
Medium 13 0.040 18 24
Heavy 23 0.044 30 36
(Channels) (Dissapators)

8.06.6 Rev. IZ93
•
•
•
•
•
•
•
•
•
•
•
•
Appendices
6o .n : n r 1; ;11Ir1
!iiAN
40-k
20 • --•_ •: li•-tij 11:1!1
rl'1?r:1?:'1 'Ji!?1111:111'
U-11i R.
L-9.181

Figure 8.06e Maximum Stone Size for Riprap
15,000
-10.000
5,000
• u
N
CO
m
1,000 2
- a
-500 L
- 250 CO
-100
-50
Based on Isbesh Curve
Maximum weight of
stone required Minimum and maximum range
in weight of stones Weight range of
75% of stones
(Ibs.) (Ibs.) (Ibs.)
150 25 - 150 50 - 150
200 25 - 200 50 - 200
250 25 - 250 50 - 250
400 25 - 400 100 - 400
600 25 - 600 150 - 600
800 25 - 800 200 - 800
1,000 50 - 1000 250 - 1000
1,300 50 - 1,300 325 - 1,300
1,600 50 1,600 400 - 1,600
2,000 75 - 2,000 600 - 2,000
2,700 100 - 2,700 800 - 2,700
Figure 8.06f Gradation of Riprap
Source, "Bank and channel lining procedures, - New York Department of Transportation, Division of Design and Construction, 197 1.
Rev. I ZM3
8.06.7
0-
0 2 4 6 8 10 12 14 16 18 20
Velocity in Feel/Sec
Exhibit 2 by H_ R_ Malcom, P. E.
C E. Dept, NCSU
Depth-Duration-Frequency Table Raleigh, NC
Location: -_? Raleigh-Durham, NC
Return Period
Duration 2-yr 5-yr 10-yr 25-yr SO-yr. 100-yr
[in) (in] (in] [in] [in] (in]
5 min 0.48 0.55 0.60 0.68 0.75 0.81
10 thin 0.79 0.92 1.02 1.17 1.28 1.40
15 thin 1.01 1.18 1.31 1.51 1.66 1.81
30 rain 1.35 1.64 1.85 2.16 2.40 2.64
60 min 1.70 2.12 2.41 2.84 3.17 3.50
2 hr 1.91 2.40 2.74- 3.23 3.61 4.00
3 hr 2.12 2.68 3.07 3.62 4.06 4.49
6 hr 2.65. 3.38 3.90 'A.62 5.19 5.75
12 hr 3.13 4.02 4.64 5.52 6.20 6.88
24 hr 3.60" 4.65 5.38 6.41 7.21 8.00
Intensity-Duration-Frequency Table
Location: -4 Raleigh-Durham, NC
Return Period -- -j
Duration 2-yr 5-yr 10-yr 25-yr 50-yr 100-yr
[w'l NOW] [ill [fir] [inArl [A'l
5 min 5.76 6.58 7,22 8.19 8.96 9.72
10 min 4.76 5.54 6.13 7.01 7.71 8.40
15 min 4.04 4.74 5.25 6.03 6.64 7.24
30 min 2.70 3.28 3.71 4.32 4.80 5.28
60 min 1.70 2.12 2.41 2.84 3.17 3.50
2 hr 0.95 1.20 1.37 1.62 1.81 2.00
3 hr 0.71 0.89 1.02 1.21 1.35 1.50
6 hr
164
0.

0.56

0.65

0.77

0.86

0.96
12 hr* 0.26 0.33 0.39 0.46 0.52 0.57
24 hr 0.15 0.19 0.22 0.27 0.30 0.33
Input Data:
Location: --j Raleigh-Durham, NC

I =_ g/(h+T)
for 5 < T < 120 min
Duration 2-yr P 100-yr P Source R
fin] [ini 2
5 169 21
5 min 0.48 0.81 NOAA HYDRO-35 10 195 22
15 min 1.01 1.81 NOAA HYDRO-35 25 232 23
60 min 1.70 3.50 NOAA HYDRO-35 SO 261 24
24 - hr 3.60 8.00 USWB TP-40 100 290 25
E--- Data -j
VI-3