20061617 Ver 1_More Info Received_20070912

WITHERS a RAVENEL
ENGINEERS I PLANNERS I SURVEYORS
lli MacKenan Drive
CARY, NORTH CAROLINA, 275ii
[phone]
FAX [phone]
To: North Carolina Division of Water Quality
2321 Crabtree Boulevard, Suite 250
Raleigh, North Carolina 27607
WE ARE SENDING YOU
^ Shop Drawings
^ Copy of Letter
® Attached
® Prints
^ Change order

oniE o /X207 los No. 020 0261.0
"'~N10N Annette Lucas
PHONE# 7 -1786
RE: Wendell Falls Subdivision
Marks Creek {0 0 02, 27- 8, C, NSW}
DWQ Pro'ect #06-1617

^ Under separate cover via _
^ Plans ^ Samples
^ Diskette ^
the following items:
^ Specifications
COPIES DATE NO. DESCRIPTION
D Detention Pond Plan
S Stormwater Manas;ement Report
THESE ARE TRANSMITTED as checked below:
® For approval ^ Approved as submitted ^ Resubmit copies for approval
^ Foryour use ^ Approved as noted ^ Submit copies for distribution
^ As requested ^ Returned for corrections ^ Return corrected prints
^ For review and comment ^ ~ O
^ FOR BIDS DUE 20 ^ PRINTS RETURNED AFTER LOAN T
SEP 1 2 2007
REMARKS:
DENR • WAT
wFn~DS MID StOR~WAIFR BRANCH
COPY TO: File SIGNED: Ken Jesneck, PE
if enclosures are not as noted, kindly notify us at once.

WITHERS
t
L~~
September 12, 2007
Ms. Annette Lucas
North Carolina Division of Water Quality
2321 Crabtree Boulevard, Suite 250
Raleigh, North Carolina 27604
Re: Additional Information Request
Wendell Falls
DWQ Project #06-1617
Marks Creek {030402. 27-38, C, NSW}
W&R Project 02050261.04
Dear Ms. Lucas:
RAVEN EL
ENGINEERS I PLANNERS I SURVEYORS
Attached you will find five (5) copies of the information requested for the proposed dry detention pond for the
future Wendell Fall Parkway. This submittal includes five plan sheets for the dry detention pond and
associated level spreader as well as the Stormwater Management Report that provides the supporting
calculations. The dry detention pond has been designed to capture the runoff from the first of precipitation
and release over a 2-5 day period. The outlet structure has been design to allow larger rainfall events to
bypass the level spreader.
I hope we have providing sufficient responses for additional information request. If you have any questions,
please feel free to contact met at [phone] or email at [e-mail].
Sincerely,
WIT ERS l A ENEL, INC.
en Jesneck, PE
Project Manager
CC: Mike Jones -Wendell Falls Residential, LLC
Qr~c~r~ae~~
SEP 1 2 2007
DENR -WATER pUALITY
WETLANDS AND STOR~''lAT6R 9RANCH
iii MacKenan Drive i Cary, North Carolina z75ii i tel: [phone] i fax: [phone] i www.withersravenel.com
7040 Wrightsville Avenue, Suite lol i Wilmington, North Carolina 28403 i tel : [phone] i fax : 91o.z56.z584
1027 Sabbath Home Road SW i Supply, NC z846z i tel: [phone] i fax: 91o.84z.8o19

~ to - I lv l ~(
WITHERS ~~ RAVENEL
WENDELL FALLS PARKWAY
STORMWATER MANAGEMENT
REPORT
Wendell Falls Subdivision
Wendell, North Carolina
Prepared For:
Wendell Falls Residential, LLC
566o Six Forks Road
Suite #202
Raleigh. NC 27609
Attn: Mike Jones
~~~~ V ~ O
Prepared By:
WITHERS &RAVENEL, INC SEP 1 2 2007
11i MacKenan Drive
Cary, North Carolina 275ii 3~A~S7TOR A~TMRNrCH
September zoo?
W&R Project No. 2o526i.o4
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WENDELL FALLS SUBDIVISION
WENDELL FALLS PARKWAY
STORMWATER MANAGEMENT PLAN
WENDELL, NORTH CAROLINA
INTRODUCTION
The purpose of this Wendell Fall Parkway Stormwater Management Report is to document the
design of the dry detention pond for a storm water outlet from the future Wendell Falls Parkway.
The primary purpose of dry detention pond 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, 2-year, 10-year, and 100-year storm events..
The site is located in Wendell, North Carolina, with the boundary approximated by US 64 Bypass
to the west, Poole Road to the south, Martin Pond Road to the east, and Knightdale-Eagle Rock
Road to the north. The overall subdivision has proposed a mixture of 4000 units of single family
and multifamily homes. In addition, approximately 250,000 square feet of commercial space is
included in the proposed subdivision. The Town of Wendell has approved the Planned Unit
Development. This report addresses the portion of the subdivision that exceeds 30% impervious.
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, 2-year, 10-year, and 100-year rainfall events for the Wendell
area
^ Formulation of the 1-year, 2-year, 10-year, and 100-year flood hydrographs for the pre-
and post-development drainage areas
Hydraulic
^ Routing the 1-year, 2-year, 10-year, and 100-year flood hydrographs for pre-
development runoff from the site.
^ Routing the 1-year, 2-year, 10-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 astage-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 2-year, 10-
year, 50-year and 100-year storm events. This method requires three basic parameters: a curve
number (CN), time of concentration (t~), and drainage area.
Wendell Falls Subdivision i W&R Project 2o526i.oq
Wendell Falls Parkway Stormwater Management Report September zoo?

WENDELL FALLS SUBDIVISION
WENDELL FALLS PARKWAY
STORMWATER MANAGEMENT PLAN
WENDELL, NORTH CAROLINA
Curve numbers were based on soil type and land use. Soil types were delineated from the Soil
Survey of Wake County, North Carolina (November 1970). Land use for existing conditions was
based on the most recent Wake County aerial photographs and field observations. 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, 2-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. Anon-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 zo526i.oq
Wendell Falls Parkway Stormwater Management Report September Zoo?

WENDELL FALLS SUBDIVISION
WENDELL FALLS PARKWAY
STORMWATER MANAGEMENT PLAN
WENDELL, NORTH CAROLINA
DRY DETENTION POND DESIGN SUMMARY
PROPOSED CONSTRUCTED WETLANDS
• Water Quality Volume = 14556 CF
• Sediment Storage = 3.200 CF
• 5' Circular Riser Crest = 258.60
• 2" diameter drawdown orifice ~ 257.00
• 30"diameter RCP outlet barrel
• Top of dam = 261.00

Storm Event Peak Water
Surface
Elevation
Freeboard
Q~ak Outflow
1" Storm 258.60 2.40 ft 0.13 cfs
2-Year 259.36 1.67 ft 25.6 cfs
10-Year 259.49 1.51 ft 27.4 cfs
100-Year 259.63 1.37 ft 33.6 cfs
Wendell Falls Subdivision 3 W&R Project zo526i.oq
Wendell Falls Parkway Stormwater Management Report September 2007

DRY DETENTION
POND/SITE OUTFLOW
CALCULATIONS
Wendell Falls Subdivision W&R Project zo526i.oq
Wendell Falls Parkway Stormwater Management Report September zoo?

Job File: K:\05\05-260\05261.04\Proj\Wendell Falls Parkway\DRYPOND.PPW
Rain Dir: K:\05\05-260\05261.09\Proj\Wendell Falls Parkway\
JOB TITLE
Project Date: 9/14/2006
Project Engineer: Ken Jesneck, PE
Project Title: Kitts Creek Phase lE
Project Comments:
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Table of Contents
i
********************** MASTER SUMMARY **********************
Watershed....... Master Network Summary ............. 1.01
*************** NETWORK SUMMARIES (DETAILED) ***************
Watershed....... 1
Executive Summary (Nodes) .......... 2.01
Watershed....... 10
Executive Summary (Nodes) .......... 2.02
Watershed....... 25
Executive Summary (Nodes) .......... 2.03
Watershed....... 100
Executive Summary (Nodes) .......... 2.04
********************** RAINFALL DATA ***********************
Distribution A.. 1
Synthetic Curve .................... 3.01
******************** RUNOFF HYDROGRAPHS ********************
WENDELL FLS PWY 1
Unit Hyd. Summary .................. 4.01
WENDELL FLS PWY 10
Unit Hyd. Summary .................. 4.02
WENDELL FLS PWY 25
Unit Hyd. Summary .................. 4.03
WENDELL FLS PWY 100
Unit Hyd. Summary .................. 4.04
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Table of Contents
11
******************** OUTLET STRUCTURES *********************
Outlet 1........ Outlet Input Data .................. 5.01
Composite Rating Curve ............. 5.05
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Name.... Watershed
File.... K:\05\05-260\05261.04\Proj\Wendell Falls Parkway\Drypond.ppw
MASTER DESIGN STORM SUMMARY
Network Storm Collection: RDU NOAA 14 Desi
Total
Depth
Return Event in
------------
10 ------
4.9800
25 5.9000
100 7.3700
1 1.4600
Rainfall
Type
Time-Depth Curve
Time-Depth Curve
Time-Depth Curve
Synthetic Curve
RNF ID
RDU NOAA l0yr
RDU NOAA 25yr
RDU NOAA 100yr
Distribution A
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
Node ID Type Event ac-ft Trun
*OUT POST-SITE JCT 10 2.011
*OUT POST-SITE JCT 25 2.474
*OUT POST-SITE JCT 100 3.224
*OUT POST-SITE JCT 1 .330
POND 20 IN POND 10 2.015
POND 20 IN POND 25 2.478
POND 20 IN POND 100 3.228
POND 20 IN POND 1 .334
POND 20 OUT POND 10 2.011
POND 20 OUT POND 25 2.474
POND 20 OUT POND 100 3.224
POND 20 OUT POND 1 .330
Max
Qpeak Qpeak Max WSEL Pond Storage
hrs cfs ft ac-ft
12.2000 25.61
12.2000 27.37
12.2000 33.59
1.0000 .13
12.1000 36.39
12.1000 41.01
12.1000 46.74
.3000 7.82
12.2000 25.61 259.36 .567
12.2000 27.37 259.49 .610
12.2000 33.59 259.63 .659
1.0000 .13 258.60 .325
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Type.... Master Network Summary Page 1.02
Name.... Watershed
File.... K:\05\05-260\05261.04\Proj\Wendell Falls Parkway\Drypond.ppw
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 Qpeak Max WSEL
Node ID Type Event ac-ft Trun hrs
-
-- cfs ft
---
--- -
---
-
---------
WENDELL ----
FLS ----
PWY ----
AREA ------
10 ---------- --
2.015 ----
--
12.1000 -
-
-
-
-
36.39
WENDELL FLS PWY AREA 25 2.478 12.1000 41.01
WENDELL FLS PWY AREA 100 3.228 12.1000 46.74
WENDELL FLS PWY AREA 1 .334 .3000 7.82
Max
Pond Storage
ac-ft
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Name.... Watershed Event: 1 yr
File.... K:\05\05-260\05261.04\Proj\Wendell Falls Parkway\Drypond.ppw
Storm... Distribution A Tag: 1
NETWORK SUMMARY -- NODES
(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
Storm Frequency
Total Rainfall Depth
Duration Multiplier
Resulting Duration
Resulting Start Time
HYG Vol Qpeak Qpeak Max WSEL
Node ID Type ac-ft Trun. hrs cfs ft
-----------------
Outfall OUT POST-SITE ----
JCT ---------
.330 - -- ---------
1.0000 -------- ---------
.13
POND 20 IN POND .334 .3000 7.82
POND 20 OUT POND .330 1.0000 .13 258.60
WENDELL FLS PWY AREA .334 .3000 7.82
Synthetic Storm Distribution A
1 yr
1.4600 in
1
1.0000 hrs
.0000 hrs Step= .0500 hrs End= 1.0000 hrs
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Type.... Executive Summary (Nodes) Page 2.02
Name.... Watershed Event: 10 yr
File.... K:\05\05-260\05261.04\Proj\Wendell Falls Parkway\Drypond.ppw
Storm... RDU NOAA l0yr Tag: 10
NETWORK SUMMARY -- NODES
(Trun.= HYG Truncation: Blank=None; L=Left; R=Rt; LR=Left & Rt)
DEFAULT Design Storm File,ID = RDU NOAA 14 Desi
Storm Tag Name = 10
Data Type, File, ID = Time-Depth Curve RDU NOAA l0yr
Storm Frequency = 10 yr
Total Rainfall Depth= 4.9800 in
Duration Multiplier = 1
Resulting Duration = 23.9904 hrs
Resulting Start Time= .0000 hrs Step= .0833 hrs End= 23.9904 hrs
HYG Vol Qpeak Qpeak Max WSEL
Node ID Type ac-ft Trun. hrs cfs ft
---- ---------
-----------------
Outfall OUT POST-SITE ----
JCT ----------
2.011 -- ---------
12.2000 ----
25.61
POND 20 IN POND 2.015 12.1000 36.39
POND 20 OUT POND 2.011 12.2000 25.61 259.36
WENDELL FLS PWY AREA 2.015 12.1000 36.39
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Type.... Executive Summary (Nodes) Page 2.03
Name.... Watershed Event: 25 yr
File.... K:\05\05-260\05261.04\Proj\Wendell Falls Parkway\Drypond.ppw
Storm... RDU NOAA 25yr Tag: 25
NETWORK SUMMARY -- NODES
(Trun.= HYG Truncation: Blank=None; L=Left; R=Rt; LR=Left & Rt)
DEFAULT Design Storm File,ID = RDU NOAA 14 Desi
Storm Tag Name = 25
Data Type, File, ID = Time-Depth Curve RDU NOAA 25yr
Storm Frequency = 25 yr
Total Rainfall Depth= 5.9000 in
Duration Multiplier = 1
Resulting Duration = 23.9904 hrs
Resulting Start Time= .0000 hrs Step= .0833 hrs End= 23.9904 hrs
HYG Vol Qpeak Qpeak Max WSEL
Node ID Type ac-ft Trun. hrs
-- --------- cfs ft
-------- ---------
-----------------
Outfall OUT POST-SITE ----
JCT ----------
2.474 12.2000 27.37
POND 20 IN POND 2.478 12.1000 41.01
POND 20 OUT POND 2.474 12.2000 27.37 259.49
WENDELL FLS PWY AREA 2.478 12.1000 41.01
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Type.... Executive Summary (Nodes) Page 2.04
Name.... Watershed Event: 100 yr
File.... K:\05\05-260\05261.04\Proj\Wendell Falls Parkway\Drypond.ppw
NETWORK SUMMARY -- NODES
(Trun.= 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-Depth 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 hrs Step= .0833 hrs End= 23.9990 hrs
HYG Vol Qpeak Qpeak Max WSEL
Node ID
- Type
-
- ac-ft
- Trun. hrs cfs ft
---------------
-
Outfall OUT POST-SITE -
-
JCT ---
------
3.224 -- ---------
12.2000 -------- ---------
33.59
POND 20 IN POND 3.228 12.1000 46.74
POND 20 OUT POND 3.224 12.2000 33.59 259.63
WENDELL FLS PWY AREA 3.228 12.1000 46.74
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Type.... Synthetic Curve Page 3.01
Name.... Distribution A Tag: 1
File.... K:\05\05-260\05261.04\Proj\Wendell Falls Parkway\Drypond.ppw
CUMULATIVE RAINFALL FRACTIONS
Time I Output Time increment = .0500 hrs
hrs ~ Time on left represents time for first value in each row.
.0000 I .000 .160 .330 .430 .520
.2500 I .600 .660 .710 .750 .790
.5000 I .820 .840 .860 .880 .900
.7500 I .920 .940 .960 .970 .980
1.0000 I 1.000
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Type.... Unit Hyd. Summary Page 4.01
Name.... WENDELL FLS PWY Tag: 1 Event: 1 yr
File.... K:\05\05-260\05261.04\Proj\Wendell Falls Parkway\Drypond.ppw
Storm... Distribution A Tag: 1
SCS UNIT HYDROGRAPH METHOD
STORM EVENT: 1 year storm
Duration = 1.0000 hrs Rain Depth = 1.4600 in
Rain Dir = K:\05\05-260\05261.04\Proj\Wendell Falls Parkway\
Rain File -ID = - Distribution A
Unit Hyd Type = Default Curvilinear
HYG Dir = K:\05\05-260\05261.04\Proj\Wendell Falls Parkway\
HYG File - ID = work_pad.hyg - WENDELL FLS PWY 1
Tc (Min. Tc) _ .0833 hrs
Drainage Area = 6.220 acres Runoff CN= 90
Computational Time Increment = .01111 hrs
Computed Peak Time = .2666 hrs
Computed Peak Flow = 8.25 cfs
Time Increment for HYG File = .1000 hrs
Peak Time, Interpolated Output = .3000 hrs
Peak Flow, Interpolated Output = 7.82 cfs
WARNING: The difference between calculated peak flow
and interpolated peak flow is greater than 1.50%
DRAINAGE AREA
ID:WENDELL FLS PWY
CN = 90
Area = 6.220 acres
S = 1.1111 in
0.25 = .2222 in
Cumulative Runoff
-------------------
.6523 in
.338 ac-ft
HYG Volume... .334 ac-ft (area under HYG curve)
***** SCS UNIT HYDROGRAPH PARAMETERS *****
Time Concentration, Tc = .08330 hrs (ID: WENDELL FLS PWY)
Computational Incr, Tm = .01111 hrs = 0. 20000 Tp
Unit Hyd. Shape Fact or = 483.432 (37.46°s 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 = 84.60 cfs
Unit peak time Tp = .05553 hrs
Unit receding limb, Tr = .22213 hrs
Total unit time, Tb = .27767 hrs
S/N: DOYXYWH3NLBE Withers & Ravenel
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Type.... Unit Hyd. Summary Page 4.02
Name.... WENDELL FLS PWY Tag: 10 Event: 10 yr
File.... K:\05\05-260\05261.04\Proj\Wendell Falls Parkway\Drypond.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:\05\05-260\05261.04\Proj\Wendell Falls Parkway\
Rain File -ID = - RDU NOAA l0yr
Unit Hyd Type = Default Curvilinear
HYG Dir = K:\05\05-260\05261.04\Proj\Wendell Falls Parkway\
HYG File - ID = work_pad.hyg - WENDELL FLS PWY 10
Tc (Min. Tc) _ .0833 hrs
Drainage Area = 6.220 acres Runoff CN= 90
Computational Time Increment = .01111 hrs
Computed Peak Time = 12.0952 hrs
Computed Peak Flow = 36.59 cfs
Time Increment for HYG File = .1000 hrs
Peak Time, Interpolated Output = 12.1000 hrs
Peak
---- Flow,
------ Interpolated
------------- Output =
--------- 36.39
---------- cfs
--
DRAINAGE AREA
ID:WENDELL FLS PWY
CN = 90
Area = 6.220 acres
S = 1.1111 in
0.2S = .2222 in
Cumulative Runoff
-------------------
3.8570 in
1.999 ac-ft
HYG Volume... 2.015 ac-ft (area under HYG curve)
***** SCS UNIT HYDROGRAPH PARAMETERS *****
Time Concentration, Tc = .08330 hrs (ID: WENDELL FLS PWY)
Computational Incr, Tm = .01111 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/(1+(Tr/Tp))
Receding/Rising, Tr/Tp = 1.6698 (solved from K = .7491)
Unit peak, qp = 84.60 cfs
Unit peak time Tp = .05553 hrs
Unit receding limb, Tr = .22213 hrs
Total unit time, Tb = .27767 hrs
S/N: DOYXYWH3NLBE Withers & Ravenel
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Type.... Unit Hyd. Summary Page 4.03
Name.... WENDELL FLS PWY Tag: 25 Event: 25 yr
File.... K:\05\05-260\05261.04\Proj\Wendell Falls Parkway\Drypond.ppw
Storm... RDU NOAA 25yr Tag: 25
SCS UNIT HYDROGRAPH METHOD
STORM EVENT: 25 year storm
Duration = 23.9904 hrs Rain Depth = 5.9000 in
Rain Dir = K:\05\05-260\05261.04\Proj\Wendell Falls Parkway\
Rain File -ID = - RDU NOAA 25yr
Unit Hyd Type = Default Curvilinear
HYG Dir = K:\05\05-260\05261.04\Proj\Wendell Falls Parkway\
HYG File - ID = work_pad.hyg - WENDELL FLS PWY 25
Tc (Min. Tc) _ .0833 hrs
Drainage Area = 6.220 acres Runoff CN= 90
--------------------------------------------
Computational Time Increment = .01111 hrs
Computed Peak Time = 12.0952 hrs
Computed Peak Flow = 41.26 cfs
Time Increment for HYG File = .1000 hrs
Peak Time, Interpolated Output = 12.1000 hrs
Peak Flow, Interpolated Output = 41.01 cfs
DRAINAGE AREA
ID:WENDELL FLS PWY
CN = 90
Area = 6.220 acres
S = 1.1111 in
0.2S = .2222 in
Cumulative Runoff
-------------------
4.7485 in
2.461 ac-ft
HYG Volume... 2.478 ac-ft (area under HYG curve)
***** SCS UNIT HYDROGRAPH PARAMETERS *****
Time Concentration, Tc = .08330 hrs (ID: WENDELL FLS PWY)
Computational Incr, Tm = .01111 hrs = 0. 20000 Tp
Unit Hyd. Shape Factor = 483.432 (37.460 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 = 84.60 cfs
Unit peak time Tp = .05553 hrs
Unit receding limb, Tr = .22213 hrs
Total unit time, Tb = .27767 hrs
S/N: DOYXYWH3NLBE Withers & Ravenel
PondPack (10.00.015.00) 2:51 PM 9/11/2007

Type.... Unit Hyd. Summary Page 4.09
Name.... WENDELL FLS PWY Tag: 100 Event: 100 yr
File.... K:\05\05-260\05261.04\Proj\Wendell Falls Parkway\Drypond.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:\05\05-260\05261.04\Proj\Wendell Falls Parkway\
Rain File -ID = - RDU NOAA 100yr
Unit Hyd Type = Default Curvilinear
HYG Dir = K:\05\05-260\05261.04\Proj\Wendell Falls Parkway\
HYG File - ID = work_pad.hyg - WENDELL FLS PWY 100
Tc (Min. Tc) _ .0833 hrs
Drainage Area = 6.220 acres Runoff CN= 90
Computational Time Increment = .01111 hrs
Computed Peak Time = 12.1063 hrs
Computed Peak Flow = 46.75 cfs
Time Increment for HYG File = .1000 hrs
Peak Time, Interpolated Output = 12.1000 hrs
Peak Flow, Interpolated Output = 46.74 cfs
DRAINAGE AREA
ID:WENDELL FLS PWY
CN = 90
Area = 6.220 acres
S = 1.1111 in
0.2S = .2222 in
Cumulative Runoff
-------------------
6.1862 in
3.206 ac-ft
HYG Volume... 3.228 ac-ft (area under HYG curve)
***** SCS UNIT HYDROGRAPH PARAMETERS *****
Time Concentration, Tc = .08330 hrs (ID: WENDELL FLS PWY)
Computational Incr, Tm = .01111 hrs = 0.20000 Tp
Unit Hyd. Shape Fact or = 483.432 (37.460 under rising limb)
K = 483.43/695.333, K = .7491 (also, K = 2/(1+(Tr/Tp))
Receding/Rising, Tr/ Tp = 1.6698 (solved from K = .7491)
Unit peak, qp = 84.60 cfs
Unit peak time Tp = .05553 hrs
Unit receding limb, Tr = .22213 hrs
Total unit time, Tb = .27767 hrs
S/N: DOYXYWH3NLBE Withers & Ravenel
PondPack (10.00.015.00) 2:51 PM 9/11/2007

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Type.... Outlet Input Data
Name.... Outlet 1
Page 5.01
File.... K:\05\05-260\05261.04\Proj\Wendell Falls Parkway\Drypond.ppw
REQUESTED POND WS ELEVATIONS:
Min. Elev.= 257.00 ft
Increment = .10 ft
Max. Elev.= 261.00 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 258.600 261.000
Orifice-Circular 00 ---> CO 257.000 261.000
Culvert-Circular CO ---> TW 256.500 261.000
Weir-Rectangular WO ---> TW 259.500 261.000
TW SETUP, DS Channel
S/N: DOYXYWH3NLBE
PondPack (10.00.015.00) 2:51 PM
Withers & Ravenel
9/11/2007

Type.... Outlet Input Data
Name.... Outlet 1
Page 5.02
File.... K:\05\05-260\05261.04\Proj\wendell Falls Parkway\Drypond.ppw
OUTLET STRUCTURE INPUT DATA
Structure ID = RO
Structure Type = Inlet Box
--------------
-------------------
# of Openings = ---
1
Invert Elev. = 258.60 ft
Orifice Area = 19.6350 sq.ft
Orifice Coeff. _ .600
Weir Length = 15.71 ft
Weir Coeff. = 2.800
K, Reverse = 1.000
Mannings n = .0000
Kev,Charged Riser = .000
Weir Submergence = No
Structure ID = 00
Structure Type = Orifice-Circular
------------------------------------
# of Openings = 1
Invert Elev. = 257.00 ft
Diameter = .1670 ft
Orifice Coeff. _ .600
S/N: DOYXYWH3NLBE Withers & Ravenel
PondPack (10.00.015.00) 2:51 PM 9/11/2007

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Name.... Outlet 1
Page 5.03
File.... K:\05\05-260\05261.04\Proj\Wendell Falls Parkway\Drypond.ppw
OUTLET STRUCTURE INPUT DATA
Structure ID = CO
Structure Type
------------------ = Culvert-Circular
------------------
No. Barrels = 1
Barrel Diameter = 2.5000 ft
Upstream Invert = 256.50 ft
Dnstream Invert = 256.00 ft
Horiz. Length = 100.00 ft
Barrel Length = 100.00 ft
Barrel Slope = .00500 ft/ft
OUTLET CONTROL DATA...
Mannings n = .0130
Ke = .5000
Kb = .009217
Kr = .5000
HW Convergence = .001
(forward entrance loss)
(per ft of full flow)
(reverse entrance loss)
+/- ft
INLET CONTROL DATA...
Equation form = 1
Inlet Control K = .0018
Inlet Control M = 2.0000
Inlet Control c = .02920
Inlet Control Y = .7400
T1 ratio (HW/D) = 1.060
T2 ratio (HW/D) = 1.205
Slope Factor = -.500
Use unsubmerged inlet control Form 1 equ. below T1 elev.
Use submerged inlet control Form 1 equ. above T2 elev.
In transition zone between unsubmerged and submerged inlet control,
interpolate between flows at T1 & T2...
At T1 Elev = 259.15 ft ---> Flow = 27.16 cfs
At T2 El.ev = 259.51 ft ---> Flow = 31.05 cfs
S/N: DOYXYWH3NLBE
PondPack (10.00.015.00)
2:51 PM
Withers & Ravenel
9/11/2007

Type.... Outlet Input Data
Name.... Outlet 1
Page 5.04
File.... K:\05\05-260\05261.09\Proj\Wendell Falls Parkway\Drypond.ppw
OUTLET STRUCTURE INPUT DATA
Structure ID
Structure Type
--------------
# of Openings
Crest Elev.
Weir Length
Weir Coeff.
WO
Weir-Rectangular
----------------
1
259.50 ft
29.00 ft
3.100000
Weir TW effects (Use adjustment equation)
Structure ID = TW
Structure Type = TW SETUP, DS Channel
------------------------------------
FREE OUTFACE CONDITIONS SPECIFIED
CONVERGENCE TOLERANCES...
Maximum Iterations= 40
Min. TW tolerance = .01 ft
Max. TW tolerance = .01 ft
Min. HW tolerance = .01 ft
Max. HW tolerance = .O1 ft
Min. Q tolerance = .00 cfs
Max. Q tolerance = .00 cfs
S/N: DOYXYWH3NLBE Withers & Ravenel
PondPack (10.00.015.00) 2:51 PM 9/11/2007

Type.... Composite Rating Curve
Name.... Outlet 1
Page 5.05
File.... K:\05\05-260\05261.09\Proj\Wendell Falls Parkway\Drypond.ppw
***** COMPOSITE OUTFLOW SUMMARY ****
WS Elev, Total Q Notes
-------- -------- ------ -- Converge ---------- --- ------------
Elev. Q TW El ev Error
ft cfs ft +/-ft
----- - Contributing
------------- Structures
------------
--------
257.00 -------
.00 ------
Free --
Outfall (no Q: RO,OO ,CO,WO)
257.10 .O1 Free Outfall OO,CO (no Q: RO,WO)
257.20 .04 Free Outfall OO,CO (no Q: RO,WO)
257.30 .05 Free Outfall OO,CO (no Q: RO,WO)
257.40 .06 Free Outfall OO,CO (no Q: RO,WO)
257.50 .07 Free Outfall OO,CO (no Q: RO,WO)
257.60 .08 Free Outfall OO,CO (no Q: RO,WO)
257.70 .08 Free Outfall OO,CO (no Q: RO,WO)
257.80 .09 Free Outfall OO,CO (no Q: RO,WO)
257.90 .10 Free Outfall OO,CO (no Q: RO,WO)
258.00 .10 Free Outfall OO,CO (no Q: RO,WO)
258.10 .11 Free Outfall OO,CO (no Q: RO,WO)
258.20 .11 Free Outfall OO,CO (no Q: RO,WO)
258.30 .12 Free Outfall OO,CO (no Q: RO,WO)
258.40 .12 Free Outfall OO,CO (no Q: RO,WO)
258.50 .13 Free Outfall OO,CO (no Q: RO,WO)
258.60 .13 Free Outfall OO,CO (no Q: RO,WO)
258.70 1.53 Free Outfall RO,OO,CO (no Q: WO)
258.80 4.05 Free Outfall RO,OO,CO (no Q: WO)
258.90 7.34 Free Outfall RO,OO,CO (no Q: WO)
259.00 11.21 Free Outfall RO,OO,CO (no Q: WO)
259.10 15.62 Free Outfall RO,OO,CO (no Q: WO)
259.20 20.49 Free Outfall RO,OO,CO (no Q: WO)
259.30 24.70 Free Outfall RO,CO (no Q: OO,WO)
259.40 26.15 Free Outfall RO,OO,CO (no Q: WO)
259.50 27.56 Free Outfall RO,CO (no Q: OO,WO)
259.60 31.76 Free Outfall RO,OO,CO,WO
259.70 38.29 Free Outfall RO,CO,WO (no Q: 00)
259.80 46.26 Free Outfall RO,CO,WO (no Q: 00)
259.90 55.41 Free Outfall RO,CO,WO (no Q: 00)
260.00 65.55 Free Outfall RO,CO,WO (no Q: 00)
260.10 76.57 Free Outfall RO,CO,WO (no Q: 00)
260.20 88.34 Free Outfall RO,CO,WO (no Q: 00)
260.30 100.77 Free Outfall RO,CO,WO (no Q: 00)
260.40 113.90 Free Outfall RO,CO,WO (no Q: 00)
260.50 127.75 Free Outfall RO,CO,WO (no Q: 00)
260.60 142.27 Free Outfall RO,CO,WO (no Q: 00)
260.70 157.43 Free Outfall RO,CO,WO (no Q: 00)
S/N: DOYXYWH3NLBE Withers & Ravenel
PondPack (10.00.015.00) 2:51 PM 9/11/2007

Type.... Composite Rating Curve
Name.... Outlet 1
***** COMPOSITE OUTFLOW SUMMARY ****
WS Elev, Total Q Notes
-------- -------- ------ -- Converge ------------- ------------
Elev. Q TW El ev Error
ft cfs ft +/-ft Contributing
------------ Structures
------------
--------
260.80 -------
173.21 ------
Free -- -----
Outfall --
RO,CO,WO (no Q: 00)
260.90 189.57 Free Outfall RO,CO,WO (no Q: 00)
261.00 206.51 Free Outfall RO,CO,WO (no Q: 00)
Page 5.06
S/N: DOYXYWH3NLBE Withers & Ravenel
PondPack (10.00.015.00) 2:51 PM 9/11/2007

Appendix A
Index of Starting Page Numbers for ID Names
A-1
----- D -----
Distribution A 1... 3.01
----- O -----
Outlet 1... 5.01, 5.05
----- W -----
Watershed... 1.01, 2.01, 2.02, 2.03,
2.04
WENDELL FLS PWY 1... 4.01, 4.02,
9.03, 4.04
S/N: DOYXYWH3NLBE Withers & Ravenel
PondPack (10.00.015.00) 2:51 PM 9/11/2007

BMP SIZING
CALCULATIONS
Wendell Falls Subdivision W&R Project zo5z6i.o4
Wendell falls Parkway Stormwater Management Report September zoo?

Project Name: Wendell Falls Parkway Dry Pond
City/State: WENDELL, NC
Total Drainage Area =
Impervious Surfaces =
Undisturbed & Managed Open Space =
Impervious Surface Area =
6.22 ac
4.11 ac
2.11 ac
66.1
Proiect #: 205261.04
Date: 11-Sep-07
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.
I =Percent impervious
Rv = 0.64 in./in.
Total runoff volume from 1-inch precipitation:
Runoff volume, S = (Design rainfall) (Rv) (Drainage Area)
S = 0.334 acre-ft
14556 cu. ft.
Proposed orifice elevation = 257 feet
Runoff storage provided = 0.335 ac-ft
BMP Sizing.xls -Dry Detention Pond
9/11 /2007

Project Name: Wendell Falls Parkway
City/State: Raleigh, NC
STORMWATER BMP -Dry Pond
Orifice Calculator

Variables
WQ Volume:
Head:
Draw down time:
Orifice Area = 0.013461 sq. ft
Orifice Diameter = 1.570991 in
0.334 Acre-ft 14549.04 cf
1.5 ft 0.75 ft
72 hrs 259200 s
1.938372 sq. in
Project #: 205261.04
Date: 11-Sep-07
Constants
g = 32.2 ft/s2
Cd= 0.6
USE 2.0" DIAMETER ORIFICE

FLOTATION AND ANTI- SEEP
CALCULATIONS
Wendell Falls Subdivision W&R Project zo5z6i.oq
Wendell Falls Parkway Stormwater Management Report September zoo?

Flotation Calculations
Project No: 02050261.01 Calc. By: KLJ
Project Name: Wendell Falls -Dry Detention Pond Date: September, 2007
Com oncnts 1'VeighLs
Wgt. HZO Wgt.Concrete Wgt. Soil (Sat)
(Ibs/cu. ft.) (Ibs/cu. ft.) (Ibs/cu. ft.)
62.40 150.00 120.00
Outlet Stru~ ure
Base Diameter Thickness
(ft) (i n)
0.00 0.00
Walls Diameter Wall Height
(ft) (ft)
Outside 5.83 2.10
Inside 5.00
Fillet Volume
(cu. ft)
0.00
Weight of Wetwell = (Outside Volume -Inside Volume + Fillet Volume) x Weight of Concrete
Walls Base Fillet Total
Weight 2,232.51 0.00 0.00 2,232.51 (Ibs)
5oi I
Soil Weight =((Base Area -Wetwell OD Area) x Height of Soil) x Weight of Soil
Total Height 0.50 (ft)
Weight -1,603.34 (Ibs)
Withers and Ravenel, Inc. Page 1 of 2

Flotation Calculations
Project No: 02050261.01 Calc. By: KLJ
Project Name: Wendell Falls - D Detention Pond Date: Se tember, 2007
Bottom Slab
Circular
Diameter Thickness
(ft) (i n) Total
0.00 0.00 0.00 (Ibs)
Rectangular
Width of slab Length of slab Thickness
(ft) (ft) (in) Total
6.50 6.50 12.00 6,337.50 (Ibs)
Hatch O enin, s
Circular
Diameter
(i n) 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)
U ward r?~ctin ~ Force
Upward Force Acting on Bottom of Structure =Base Area x Height of Water x Weight of Water
Total Height 3.10 ( ft)
Buoyancy Force 5,169.16 ( Ibs)
Factor of Safet ~.,; :;
Factor of Safety =Downward Force of Structure and Soil/Upward Force of Water
Total Downward Force 6,966.68 (Ibs)
Total Buoyancy Force 5,169.16 (Ibs)
Factor of Safet = 1.35
Withers and Ravenel, Inc. Page 2 of 2

~~
",
• ~
`~
~~
-: ,.
Desi¢nine Anti-Seep Collars (Refer to Detail 13)
1. Determine the length of pipe within the saturation zone of the embankment (Ls) either graphically
or by using the following equation, ..assuming that. the upstream slope of the embankment intersects
the invert of the pipe at.its .upstream end and that the slope of the pipe (S,) is constant.
Ls = Y Z+4
(1-4 So)
2. Determine the vertical projection (P,) required to`increase L, by 15% either graphically as shown
on G10-22 or by using the equation:
P, = 0.075 Lt
3. Choose the actual vertical projection (2' minimum) of each anti-seep collar (P) by rounding up P,
or rounding down P, and using multiple-collars.
4. Determine the number of anti-seep collars (N) required of the chosen vertical projection (P) using
equation:
P, = N.
P
5. Either roundup N or repeat steps 3 and 4 to determineoptimum-PIN relationship.
6. Provide construction specifications relative to the materials. to be used and method for anchoring
the anti-seep collar(s) to the pipe in a water tight manner.
7. Anti-seep collar spacing shall .be between 5 and 14 times the vertical projection of each collar.
8. Anti-seep collar dimensions shall extend :a ,minimum of 2 feet in all directions around the pipe.
9. Anti-seep collars shall be placed a minimum of two .feet from pipe joints.
10. Anti-seep collars should be placed within the saturation zone. In cases where the spacing limit
will not allow this, at least one collar shall be placed in the saturation zone.
C-10-21
1994

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DETAIL 13 - ANTI~EEP COLLAR DESIGN
RISER CREST Y/,t~~!/,A~'/,A
_ ~,
- _ = ASSUMED
~ PHREATIC EMBANKMENT
LINE
Y ~'~ \
P ~ 9•~
-------------------------- S
EMBANKMENT ~ o
INVERT
INTERSECTION
Ls

PIPE DIAMETER
WILL VARY
ANTI-SEEP COLLAR DESIGN
where: p= vertical projection of anti-seep collar(ft).
Ls = length of pipe in the saturated zone (ft.)
y= distance in feet from upstream invert of pipe to highest normal
water level expected to occur during the life of the structure.
usually the top of the riser.
2= slope of upstream embankment as a ratio of z ft. horizontal to
one ft. vertical.
so= slope of pipe in feet per foot.
This procedure is based on the phreatic line as shown in the drawing above:
II.3. DEPARTMENT OF AGRICULTURE PAGE MARYLAND DEPABZMEN'P OF ENVIRONMENT
SOII. CONSERVATION SERVICE C - 10 - 23 WATER MANAGEl1l~NT ADMIN89TSATION

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ISO
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100
v
0
0
N ~
0
Table 16
ANTI -SEEP COLLAR DESIGN
C-10-22
fbw pOth.
~I ~f )
10
9
8 ;,
N_
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6 c
U
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4 ~c
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2
1
1994

OPERATION AND MAINTENANCE
AGREEMENTS
Wendell Falls Subdivision W&R Project zo5z6i.oq
Wendell Falls Parkway Stormwater Management Report September zoo?

~ WENDELL FALLS SUBDIVISION
• DRY DETENTION POND
OPERATION AND MAINTENANCE AGREEMENT
i
• The dry detention basin system is defined as the dry detention basin, pre-treatment including forebays and the
• vegetated filter if one is provided.
Maintenance activities shall be performed as follows:
1. After every significant runoff producing rainfall event and at least monthly:
• a. Inspect the dry detention basin system for sediment accumulation, erosion, trash accumulation,
vegetated cover, and general condition.
b. Check and clear the orifice on the skimmer of any obstructions such that drawdown of the temporary
• pool occurs within 2 to 5 days as designed.
~ 2. Repair eroded areas immediately, re-seed as necessary to maintain good vegetative cover, mow
• vegetative cover to maintain a maximum height of six inches, and remove trash as needed.
3. Inspect and repair the collection system (i.e. catch basins, piping, swales, riprap, etc.) quarterly to
• maintain proper functioning.
4. Remove accumulated sediment from the dry detention basin system semi-annually or when depth is
reduced to 75% of the original design depth (see diagram below). Removed sediment shall be disposed
• of in an appropriate manner and shall be handled in a manner that will not adversely impact water quality
(i.e. stockpiling near a detention basin or stream, etc.).
• The measuring device used to determine the sediment elevation shall be such that it will give an accurate
depth reading.
• When the sediment depth reads 0.75 feet in the main pond, the sediment shall be removed.
When the sediment depth reads 0.75 feet in the forebay, the sediment shall be removed.
BASIN DIAGRAM
Top of Dam Elevation 261.0 ft
Sediment emoval EI. 257.7 7
-------------- -- Sediment Removal Elevation 257.75 ft 75%
---------------------------------1---~-~---~-~-- ------
Bottom E vation 257.0 5%
i o
FOREBAY MAIN POND
• Page 1 of 2

5. Remove cattails and other indigenous wetland plants when they cover 50% of the basin surface. These
plants shall be encouraged to grow along the vegetated shelf and forebay berm.
[For wetlands: Wetland planting densities in the marsh areas should be maintained by replanting bare
areas as needed. Wetland plants should be encouraged to grow in the marsh areas.]
6. If the basin must be drained for an emergency or to perform maintenance, the flushing of sediment
through the emergency drain shall be minimized to the maximum extent practical.
7. All components of the wet [wetland] detention basin system shall be maintained in good working order.
8. Level spreaders or other structures that provide diffuse flow shall be maintained every six months. All
accumulated sediment and debris shall be removed from the structure, and a level elevation shall be
maintained across the entire flow spreading structure. Any down gradient erosion must be repaired and/or
replanted as necessary.
I acknowledge and agree by my signature below that I am responsible for the performance of the seven
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.
Print name: ~?:E~ ,dS+ n1
Title: /Ll~iw4Gc~l~
Address:_ SGG'o S~jc- ~o~_~it~L'~71~L
Phone: 9/9 - ECG ~s"1A~
> >
Signature:
Date:
Note: The legally responsible party should not be a homeowners association unless more than 50% of the
lots have been sold and a resident of the subdivision has been named the pre ident.
1, ~tt~.iss ~ JA J r •
a Notary Public for the State of ~'rn ~~'~'
County of Wl~-~ , do hereby certify that ~ ~~US~a{ '
personally appeared before me this ~ day of 7.t ,and acknowledge the due
execution of the forgoing wet (wetland] detention basin maintenance requirements. Witness my hand and
official seal,
~~ ~~ *,.
~ *~ J
~~•
~:.F COVN~
My commission
~~. ?~j
Page 2 of 2

WORKSHEETS
Wendell Falls Subdivision W&R Project zo5z6i.oq
Wendell Falls Parkway Stormwater Management Report September 2007

DIVISION OF WATER QUALITY -LEVEL SPREADER WORKSHEET (1/2007)
• I. PROJECT INFORMATION (please complete the following information):
Project Name : Wendell Falls Parkway
Contact Person: Ken Jesneck. PE Phone Number: X919 1467-~s4o
• Level Spreader ID: Out 3
i
Level Spreader Length g ft. (perpendicular to flow)
Drainage Area 6.22 ac. (on-site and off-site drainage to the level spreader)
Impervious Area 4.11 ac. (on-site and off-site drainage to the level spreader)
Forebay Area 54o cu ft. (0.2% of the contributing impervious surface area)
Maximum Filter Strip/Buffer Slope 5.5 % (6% for forested/leaf littler cover, 8% for grass/thick cover)
Max. Discharge from 1°/Hr Storm 0.13 cfs
Max. Discharge to Level Spreader 0.13 cfs (Discharge rate from extended detention wetland or pond)
Filter Strip/ Zone 1 Buffer Vegetation Forested (Grass/Thick ground cover or Forested)
Filter Strip/ Zone 1 Buffer Width 30 ft.
Filter Strip/ Zone 2 Buffer Vegetation Grass
Filter Strip/ Zone 2 Buffer Width 20 ft.
Bypass Method Used Dro Detention Etc Please include a worksheet for this.
II. REQUIRED ITEMS CHECKLIST
Initial in the space provided to indicate the following design requirements have been met and supporting documentation is
attached. If a requirement has not been met, please explain why. At a minimum, a complete stormwater management plan
submittal includes a worksheet for each BMP, design calculations, plans and specifications showing all BMPs and outlet
structure details, a detailed drainage plan and a fully executed operation and maintenance agreement. An incomplete
submittal package will result in a request for additional information and will substantially delay final review and approval of
the project.
Applicants Initials
KLJ Project Site was visited prior to designing level spreader system.
KLJ Date of the Site visit. Please attach time-dated digital photos of existing buffer conditions.
KLJ Level spreader length is at least: 13 ft. per cfs for thick ground cover /grass; OR 65 ft per cfs for 50-
foot canopied forest with leaf litter; 50 ft per cfs for 100-foot forested buffer; 40 ft. per cfs for 150-foot
forested buffer; OR a weighted average of the two vegetation types within the buffer/filter strip).
KLJ All ground cover types and their widths have been labeled on the construction plans.
KLJ All contours have been depicted on the construction plans.
KLJ No structures are located in protected buffers (must meet no practical alternatives criteria).
KLJ No draws are located in the buffer or filter strip in the vicinity of the proposed level spreader.
KLJ Construction details for the level spreader have been provided.
KLJ The operation and maintenance agreement signed and notarized by the responsible party is provided.
N/A No practical alternatives explanation + Variance request. (Level Spreaders in Series only).
Bypass method used:
Dry Detention Bypass conveyance method is specified and construction details and calculations are provided.
N/A Alternative design option is specified and plan details and calculations are provided.
KLJ Discharge to level spreader and subsequent filter strip is hydraulically and spatially separate from the
bypass discharge.
KLJ Construction details for the bypass and outlets are provided.

Project No.
DIVISION OF WATER QUALITY
401 EXTENDED DRY DETENTION BASIN WORKSHEET
DWQ Stormwater Management Plan Review:
At a minimum, a complete sormwater management plan submittal includes a worksheet for each BMP, design calculations, plans and
specifications showing all BMPs and outlet structure details, a detailed drainage plan and a fully executed operation and maintenance
agreement. An incomplete submittal package will result in a request for additional information and will substantially delay final review and
approval of the project
I. PROJECT INFORMATION (please complete the following information):
Project Name : Wendell Falls Parkway
Contact Person: Ken Jesneck, PE Phone Number: j919 ) 467-3340
For projects with multiple basins, specify which basin this worksheet applies to:_
Drainage Area: s.zz acres Percent Impervious Area: 66_~
II. REQUIRED ITEMS CHECKLIST
The following checklist outlines design requirements per the Stormwater Best Management Practices Manual (N.C. Department of
Environment, Health and Natural Resources, November 1995) and Administrative Code Section: 15 A NCAC 2H .1008. Initial in the space
provided to indicate the following design requirements have been met and supporting documentation is attached. /f a requirement has not
been met, attach an explanation of why.
A licants Initials
Either capture runoff from 1 yr., 24 hour storm and release over a 48 hour period, or
capture runoff from 1 inch storm and draw down over a period of 2 to 5 days.
Please provide routing for 1 yr. 24 hr. event or volume from 1 inch rain 1 ~ ~ S~• 1'T 3
The basin length to width ratio is greater than 3:1.
The basin side slopes are no steeper than 3:1.
A small permanent pool at outlet orifice is provided to reduce clogging.
An emergency drain to completely empty the basin is provided.
Vegetation plan prepared is specified on plans.
Basin to be stabilized within 14 days of construction is specified.
Sediment storage (20% of detention volume) in addition to detention volume is provided.
Inlet and outlet erosion control measures to prevent scour are provided.
Additional treatment to meet the 85% TSS removal efficiency is provided.
Access for clean-out and maintenance is provided.
Inlet plunge pool or other energy dissipation is provided.
Forebay is provided to capture sediment and minimize clean-out problems.
Uncompacted natural soils are utilized to promote vegetation and reduce sedimentation.
Seasonal high water table is at least 1 foot below bottom of basin.
If used as a temporary sediment basin, plans indicate clean-out prior to final operation.
A site specific operation and maintenance plan with the following provisions is provided.
The 0&M agreement is signed by the responsible party and notarized.