20061436 Ver 1_Stormwater Info_20070304

FR~ELAND and KAUFFMAN, INC.
EMGIl1EER5 • LAl1~5CAPE fIR(a'-®'TECTS
March 27, 2007
Ms. Annette Lucas
Raleigh Regional Office
NC Division of Water Quality - 401 Unit
2321 Crabtree Blvd.
Raleigh, IVC 27604
[phone]
Re: Stormwater Management Clarification -Permit DWQ#06-1436
Proposed Lowe's of Waxhaw
Waxhaw. NC
Dear Ms. Lucas:
Affiliate
Freeland-Kauffman
and Fredeen, Inc.
Bentonville, Arkarwas
Enclosed you will find a revised Wet Detention Basin Supplement for Stormwater Pond #2
for the proposed Lowe's of Waxhaw in Waxhaw, North Carolina. Storage capacity of
Stormwater Pond #2 has been increased since receiving approval from NCDENR DWQ,
dated January 30, 2007. This revision was made to further reduce the post-developed
flow rate released from the pond. The previous drainage area and percent impervious ratio
remain unchanged. This submittal consists of two (2) copies of the revised wet detention
basin supplement for Stormwater Pond #2, two (2) copies of the revised grading plan, and
a copy of the DWQ Stormwater Management Plan approval letter, dated January 30,
2007. Please call or email me to confirm receipt of this package.
If there are any questions or comments concerning this submittal, don't hesitate to call me
directly at [phone].
Sincerely,
Craig S. Winn , PE
[e-mail]
z~
~J
~,~.
Enclosures: Wet Detention Basin Supplement - (2 copies)
Grading Plan (SP-2) Sheet - (2 copies)
209 West Stone Avenue • Greenville, South Carolina 29609 • Telephone [phone] • Fax [phone]

`~ ~ ' ° Nlicha~l f". I a:ie~~Goecmor
~r-; Williani(~.I{us.l `recrctary
North C"ari~lina Department of fi:nvironment ind Naha al Rc~nuron,
~ ~ 5 ~ ~ ~ ~~~ 7,
~ Alan bt Kfinul~, F f D iec.or
`-' ° ~. ~~ ~ '~~._~ ~~ Division of Vv it ~ Q~tiatity
~ -~' Coleen 1I. sullies, Deputy liirector
Division of Water Quality
January 30, 2007
l'raject Name: Cnthbertson (Cowes) Commercial Site
Union County
DWQ #06-1436
Ms. l~. Karen Partec
Director of Coi~structia~~ Admi>~istration
Cuthbertson Rd. 1, I~I,C'
6525 Mor~-isan Boulevard
Charlotte, NC 28211
Subject Praper~y: Cutherhertsan and Providence load Co7x>mercial Village
t1T W. Fork. TwelvenZile Creels [03083b, 11-1311-I, C']
API']ROVAI, (9F ST'()RMWA'I'El~ MANAGEMENT >Pl1AN
Dear Ms. I'artee:
(Jrt November, the Division of W~,>ter Quality (DWQ) received the: revised storznwater n~tan~~igemcnt plan prepared 'by your
engineer, Mr. Craig Winnall of EMH &T Inc. T"his Plan has been reviewed and satisfies the storznwater management
conditions of the ~O1 Water Quality Certification issued on October l6, 2006, provided that `I'ypha spp. (Cattail} is
omitted from the wet detention basin planting plan.
':l'he stn.lctural storznwater practices as al~~proved by DWQ as well as drainage patterns must be nlaintainecl ira pe~petuzty.
No changes to the structural storznwater practices shall be made without written. authorisation from the DWQ.
Stoi-mwater easements shall be recorded for a distance of at 'least l0 feet o~n each side of all stormw~~tter conveyances on all
lots containing these structures including fiah~zre across for maintenance. The storr~:lwater easements shall allow for the
ability to maintain the structures, pe~~~form corrective actions as described above and shall provide pr~otect~ion of the
structtu~es from poter~ltir~tl alternations by future property o~~~l.~ers.
't'(1is letter ronapletes tl~te review of`the': I)WQ t_tndet `;ectic~n 4C)l c7fthe (,,lean Witter ~c;t_ If~yo?? have any clur>stions,
please cotlt~tct me at 919-715-3~'f2.5.
Sil;~c;erEl}r,
/~_ ..~~
- A1e~>C~ette I~a~cas, E~virc>;nr~~nts~tl Y+;nia~eer ~~I
40~ t3ve~r5igittJ~xpa•ess Itevievt~ ~~e;r>rnittin~ LT>t~it
CBKlarftl
~~_:~`
~~
1~I. C'. Division of Water Quality, 401 Wctian~is Cer'd[ic<ition Unit, ~~
16~O Mail tiert~ice Center, Raleigh, NC" 7.7(199-t Ei~O (Mailin AdOress)
237 t Crabtree f3(vd., IZale~igh, NC :?"I(i(l-=t-1160 (1.~cation)
(919) 7:31-I"l8(i (phone), 919-?33-(iK91 (f tx;l, (iit_3 (1,~~ cry 5~<a~.n( i i~ bx i'.[u iei,Pi?
C'ustorricr Se:~rvice #: I -871-(i~3-67a}`3

06 1~13C> ('uthcrbcetson (Lo~X;csj Conuncrcia? Sitc
January 3(}, 2007
('ale 2 of 2
cc. Army Corp of Engir~cers, Ashcvillc
Alan Johnson, .MRO
Land Qr~tality, MRO
Becky Pox., I3Pn.
Central Pilcs
Pi 1c C;opy
Lcn Ttindncr
OFi1436Cr.rthbertson(L.owesj(.:on~mercialSite(Union)_SW_aK~prvve

Permit No. ~ ~ ' 1 ~','~o
(to be provided by DWQ)
DWQ Stormwater Management Plan Review:
A complete stormwater management plan submittal includes an application form, a wet detention basin
supplement for each basin, design calculations, and plans and specifications showing all basin and outlet
structure details.
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
WET DETENTION BASIN SUPPLEMENT
This form maybe photocopied for use as an original
I. PROJECT INFORMATION
Project Name: ~G'riyi4~l~'TScnd /~~~~ (~'G~4~~Lc^~'~tiv/
Contact Person: ~~"jZC /ir/wiCL~ Phone Number: (~ ) l~! ~Z ~~~/~~
For projects with multiple basins, specify which basin this worksheet applies to:.5~~/~ni`'~1~`~- f ~d ~Z
elevations
State of North Carolina
Department of Environment and Natural Resources
Division of Water Quality
Basin Bottom Elevation ~~ ~` ~~ ft. (floor of the basin)
Permanent Pool Elevation ~~ ~' OQ ft. (elevation of the orifice)
Temporary Pool Elevation ~f 9• l ~' ft. (elevation of the discharge structure overflow)

areas
~~
~
Permanent Pool Surface Area i ~
~j sq. ft. (water surface area at the orifice elevation)
Drainage Area n
~~• ~r+ / ac. (on-site and off-site drainage to the basin)
Impervious Area ~ ~~ s~ ac. (on-site and off-site drainage to the basin)
volumes
Permanent Pool Volume
Temporary Pool Volume
Forebay Volume
o~ ~ 7 ~ ~ cu. ft.
! ~ '~j cu. ft.
~ ~ ~"'7 i cu. ft.
(combined volume of main basin and forebay)
(volume detained above the permanent pool)
(approximately 20% of total volume)
Other parameters
SA/DA1
Diameter of Orifice
Design Rainfall
Design TSS Removal Z
Forni SWU-102 Rev 3.99
3,10
~ in.
/• ~ in.
--~.~.-
(surface area to drainage area ratio from DWQ table)
(2 to S day temporary pool draw-down required)
(minimum 85% required)
Page 1 of 4

Footnotes:
When using the Division SA/DA tables, the correct SA/DA ratio for permanent pool sizing should be computed based upon the
actual impervious % and permanent pool depth. Linear interpolation should be employed to determine the correct value for non-
standard table entries.
In the 20 coastal counties, the requirement for a vegetative filter may be waived if the wet detention basin is designed to provide
90% TSS removal. The NCDENR BMP manual provides design tables for both 85% TSS removal and 90% TSS removal.
II. REQUIRED ITEM5 CHECKLIST
The following checklist outlines design requirements per the Stormwater Best Management Practices Manual
(N.C. Department of Environment, Health and Natural Resources, February 1999) 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. If the applicant has designated an agent in the Stormwater Management Penmit
Application Form, the agent may initial below. If a requirement has not been met, attach justification.
Applicants Initials
~~ a.
b.
~~ c.
1J (j-~ d.
bR-~ e.
~~ f.
~~- 8•
~~ h.
i.
D~.~3 ;.
The permanent pool depth is between 3 and 6 feet (required minimum of 3 feet).
The forebay volume is approximately equal to 20% of the basin volume.
The temporary pool controls runoff from the design storm event.
The temporary pool draws down in 2 to 5 days.
If required, a 30-foot vegetative filter is provided at the outlet (include non-erosive flow
calculations)
The basin length to width ratio is greater than 3:1.
The basin side slopes above the permanent pool are no steeper than 3:1.
A submerged and vegetated perimeter shelf with a slope of 6:1 or less (show detail).
Vegetative cover above the permanent pool elevation is specified.
A trash rack or similar device is provided for both the overflow and orifice.
k. A recorded drainage easement is provided for each basin including access to nearest right-
of-way.
1. If the basin is used for sediment and erosion control during construction, clean out of the
basin is specified prior to use as a wet detention basin.
m. A mechanism is specified which will drain the basin for maintenance or an emergency.
III. WET DETENTION BASIN OPERATION AND MAINTENANCE AGREEMENT
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 0 does not incorporate a vegetated filter at the outlet.
This system (check one) 0 does does not incorporate pretreatment other than a forebay.
Form SWU-]02 Rev 3.99 Page 2 of 4

.~
Maintenance activities shall be performed as follows:
After every significant runoff producing rainfall event and at least monthly:
a. Inspect the wet detention basin system for sediment accumulation, erosion, trash accumulation,
vegetated cover, and general condition.
b. Check and clear the orifice 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 wet 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 wet 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 and not readily penetrate into accumulated sediments.
When the permanent pool depth reads 3- Q
When the permanent pool depth reads ~' ~
feet in the main pond, the sediment shall be removed.
feet in the forebay, the sediment shall be removed.
BASIN DIAGRAM
X11 in the blanks)
~ Permanent Pool Elevation ~ ' GEC''
Sediment Re oval El. ~~S' `f~ 75 °
---------- - Sediment Removal Elevation SAS, CO 75%
----
BottomEle ation S/~.at7 ~ % -------------------------------------
Bottom Elevation S/y. 25 /o
FOREBAY
MAIN POND
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.
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.
Form SWU-102 Rev 3.99
Page 3 of 4

• .~
7. All components of the wet detention basin system shall be maintained in good working order.
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.
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
I, r ~ / ~ ~ / S 1 , a Notary Public for the State of ~~ /- l9 /c~L1~l. ,
County of - [.' t ~ ' Y , do hereby certify that ~~ . ~ ~N ~'~/~/C
personally appeared before me this ~C~rH day of ~/-{ ,~~~~ ,and acknowledge the due
execution of the forgoing wet detention basin maintenance requirements. Witness my hand and official seal,
SEAL
My commission expires /C}`.~?~~~f'
Form SWU-102 Rev 3.99 Page 4 of 4
Print name: Gt~1~2T•.5a1..1 ~O • _?. LLG G/o ~ STb~I/ ~~Go+°g2.tlc5 . ~/~G -
T i t l e: 1'y(.kN~.G E~2„
Address: ~,25~ YhoK.~lsn~-/ 3Gtro STS ~~ G~~+21.07~. /~G 28211

Lowe's of Waxhaw~ NC March 27.2007
Calculations for: Stormwater Pond #2 1"Rainfall-Event
31.69 Acres Total drainage area, 90% impervious coverage (worst case)
R,~0.05 + 0.009(I); where I= 90%; therefore, Rr-0.86(in/in)
Volume = (1 in) x (0.86 in/in) x (1 ft/12in) x (31.69ac) = 2.27 ac-ft = 98,881 f~
At Elevation 519.10'
This volume must be stored and released in pond between 2 and 5 days (3.5 days for design).
Flow required to achieve this: (98,881 CF = 84 HRS) X (1 HR/ 3600 sec) = 0.32 CFS
Orifice Invert = 518.0
Head = 519.10-518.0 = 1.10'
Area of Orifice = Q = {0.6,~2gh)} = 0.32 CFS = {0.6f(2(32.2)1.10)} = 0.063 SF = 9.12 in2
Diameter of Orifice = 3.4" Use 3.5" common size
Flow through 3.5" orifice = 0.6(0.067) ~{2(32.2)1.10} = 0.34 CFS
Actual release time based on common size orifice = 3.37 days
Calculation for: Wet Pond #2 Emergency Drain Sizing
Permanent Pool Volume = 296,440 ft3 ;Depth = 4 ft ;Volume must be drawn down within 48 hours
(172,800 sec); therefore, Q = (296,440 ft3 / 172,800 sec) = 1.71 ft3/sec
Q/iraerKency = 0.6A 2x32.2xH ~ 1.71cfs = 0.6A 64.4x4' .•. D = 5.7in.
Use a common orifice size of 6.0 inches.
FREELAND and KAUFFMAN, INC.
ENGINEERS -LANDSCAPE ARCH/TECTS
D RB
209 West Stone Ave
Greenville SC 29609
864-233-5497