20051742 Ver 1_More Info Received_20060118

January 18, 2UUti
Division of Water Quality
Mr. Samuel Agllinriien
16501v.IaiI Service Center
401 Wetlands Clnit
Raleigh, North Carolina 27699-1650
Subject:
~~'1~
Dear .
VanDokkuzn Xtesidence
2500 Lewis Farm Road
DWQ Project # OS-1.742
Minor Variance Explanation
Ralelgla, Wake County
~n November 1 S, 2005, Ian McMillan of your Offece requested addit
buffer impact proposed. at the VanUokkum residence. ~1'he information
the location of the inlet structure for the stormwater control device
pter~erated from the prapbsed garage, 'T'liie was provided Decer-iber 15, 2
To further explain the situation at the VanDokkum Residence, I offer the
1 information far the
tested was to provide
treat the starT[iwater
1. The existing ittipervious surfaces within Zones 1 and 2 v the protected buffer
(totaling 328 square feet) will be ramovcd. The construction f the gar>igc and die
associated driveway will add S66 square feet of impervious (only ne 2 r~agacts). This
yields a net increase of 238 square feet of new impervious.
2. In order to attain caza7gliatice with the intent of the buffo rules, my client Itas
proposed flit coAistructiun of a tool gaiilen a1,11ie sear tv [root llza s~ rmwater generated by
the new garage (305 square feet witlxin Zane 2). The site plans aside a b X 12 X 4
feat area for this treatment unit. This will create a surface area I f b8 to ~2 square feet
with a total treatment volume of 272 to 288 cubic feet. ~
Since there is no worksheet far a rain garden, tlxc drainage and imperviods area, soil infiltration
rate, and other calculations from the bioretention worksheet were provide to show the treatment
capacity of thQ rain garxlea. All new stormwater generated Pram the pnrtio of the garage located
within. the protected buffer will be "guttered" to the rain garden. Inflow to a rain garden wi11 be
controlled by a stono velocity dissipator pad. Flaws in excess of normal ain events that exceed
the capacity of the facility will be allowed tv disclxargo tYarougl>I an overfio catch basin to a stone
velocity dissipater pad.
If you have any questions er are in need of additio~oial ir~ar~mation, pl do not hesitate to
contact me. I can be reached at either [phone], nig t$ at 550-9055, or
srmitchel151t'}u~.yahoo.com. Thrtnk you in advance for your prompt censide flea of this matter.
.~
Steve Mitchell ~
srm:vandoksam.let -~j
_Ti=~hJ-1'?-`t16=1r~ THIJ t_~~~: E^ TEL:'~1'~ i ~36tJ93 I•JH : D4JQ-l•JETLHhJDS F'. 1

DWQ Pro}ect No.
DIVISION OF WATER QUALITY • BIORETENTION AREA WORKSHEET
!. PROJECT INFOR TION (please complete
Project Nameme
Contact Person: ~~ ~ t`'t~
For projects with multiple basins, specify
Permanent Pool Elevation
Temporary Pool Elevation
Bioretention Surface Area
Drainage Area
impervious Area
Rational C Coefficient
Size
inlet Velocity
inlet flow depth
Depth to Ground Water
Planting Soil Infiltration Rate
!n-Situ Soil Infiitra#ion Rate
Il. REQUIRED ITEMS CHECKLIST
following information):
~"'l/~~~-~:-- ~~j1 Ll-~ Phone Number.
basin this worksheet applies to:
-~' Z ~ 0 ~ 4~C3 ft.
~ Z.~f 7 - ~~ ft.
~~ sq. ft
p Z. ac.
7 ac.
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(elevation of the orifice invert out)
{elevation of the outlet stn~cture invert in)
(on-site and off-sits drainage to the basin)
(on-site and off-site drainage to the basin)
(either 5% in wlsand under drain or 7% iri wlo
~ fps
~ in
~, D Z- in.lhr. {the soil layer downto 4 feet)
n~ ~-,~ in.ihr. (the soil layerbelow 4 feet or below the sand bed)
Initial in the space provided to indicate the following design requirements have been met and supporting documentation is attached. if a
requirement Eras not been mat, attach an explanation of r+vhy. At a minimum, a complete stormwater management plan submittal includes
a worksheet for each BMP, design calculafions, .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
Aopiicants Initials
~-u~~-- No vertical sand bed is proposed .
The bioretention area is at least 40 feet by 15 feet --~d~cz--1 ~-Jv4at-t/ ~~~,,{ tS T~~.,q-"7~.c7
t,/t Sheet flaw is provided at inlet.
`-t'v~ti Water table depth is greater than 6 feet
~~t, Minimum of 6" ponding is provided.
v~ The ponded arsa wiA draw down in less than 4 days.
Planting soil infiltration rate is greater than 0.52 in/hr.
~~ The in-situ soa infiltration rate is greater than 0.2 inihr.
""~yi ~ A planting plan with species and densities is provided. -- ~~~~ `rti "~~'~~'~~`' ~' wr' C°`'~~ ~. ~~'G~ ~~r`"~'~ u'~`"~
Mulch layer is specified in plans.
~"C~-1, Planting soil meets minimum soil specifications (NCDENR Stormwater Best tvlanagement
Practices Manual, April 1999)
_ '"Z~a~~: Plan details for the bioretention area provided.
~C~ - Plan details for the inlet and outlet are provided. {
An operation and maintenance agreement signed and notarized by the responsible party is provided. -~~! /k
~-ct11S~
Please note that underdrains beneath the planting soli are acceptable in the Piedmont and Mountains

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SCALE: I/Ib"=10'-0" NOTE PLANTING FOR THE RAIN GARDEN WILL CONSIST OF NATIVE
SPECIES PLANTED AT A RATIO OF 3Z5 PER ACRE
9 BEPfEhBER 2005
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AS A BUFFER
RG1-1 RAIN C-~ARD~N S I ~'~ PL~,N
SCALE VI6"-I'-0" NOTE= PLANTIN4 FOR THE RAIN 4ARDEN WILL CON918T OF NATIVE
SPECIES PLANTED AT A RATIO OF 926 PER ACRE
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• " • ~ . ' • ' . • :.:.: .:.:.:.:.:. : .:.:.: .:.:. ; .:.:.:.:.:.:...:.:. ~ RG4-2 TREE CALCULATIONS
. • . • • • '.'.'. '.'.'.'.'.'.'.'.'. .'.'.'.'.'.'.'.'.'. '.'.' b BASIN AREA: 72 SQ.FT.
• " " " " " " " " " " " " ' " ' ~ TREES PER ACRE: 325 X 0.002 AC
• ~ •••• ••••••••• ••••••••••••••' REQUIRED TREES: 0.65 ~ 1 TREE
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RG4-3 PLANT LIST
QUA KEY ROTA ICAL AME COMMO AME SIZE
2 CC Cercis canadensis Eastern Redbud 5-6
6 1-IYP N ricum atulum St. Johns Wort 3 Gal.
5 IVN Ilex vomitoria Nana Dwarf Yau on 3 Gal.
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SCALES i/Q~I'-0' NOTE. PLANTING FOR THE RAIN GARDEN WILL CONSIST OF NATIVE
SPECIES PLANTED AT A RATIO OF 325 PER ACRE

DWQ Project No. ~ ~ "• I ~--
DIVISION OF WATER QUALITY - BIORETENTION AREA WORKSHEET
I. PROJECT INFORM TION (please complete the following information):
Project Name : ,~ C~ , ty tv tv~ . ~l/~-t~j
Contact Person: E.~14. i'l,~ v
For projects with multiple basins, specify
Permanent Pool Elevation
Temporary Pool Elevation
Bioretention Surface Area
Drainage Area
Impervious Area
Rational C Coefficient
Size
Inlet Velocity
Inlet flow depth .
Depth to Ground Water
Planting Soil Infiltration Rate
In-Situ Soil Infiltration Rafe
0-x(0
± ZC10 ~ ~D ft. (elevation of the orifice invert out)
~ ~~ . as ft. (elevation of the outlet structure invert in)
l9~ sq. ft
©• Z ac. (on-site and. off-site drainage to the basin)
Z ac. (on-site and off-site drainage to the basin).
D
{either 5% in w/sand under drain or 7% iri w/o)
~ fps
® in ..
- ~ ft ~ ..
Z in./hr. (the soil layer down to 4 feet)
4~ Z inJhr. (the soil layerbelow 4 feet or below the sand bed)
II. REQUIRED REMS CHECKLIST
Initial in.the space provided to indicate the following design requirements have been met and supporting documentation is attached. Ifa -
requiremenfhas not been met, attach an explanation of why. At a minimum, a complete stomiwater management plan. submdtal includes
a worksheet for each BMP, design calculations, plans and .specifications showing -aIF BMPs and outlet stnrcture .details, a detailed
drainage plan and a fully executed operation and maintenance agreement An incomplete submittahpackagewiIl result in a requestfor.
additional Information and will substantially delay final review and approval of the. project
A licants Ini ials
No vertical sand bed is proposed
The bioreteotion area is at least 40 feet by 15 feet -~~~z.~ ~w ,q-~r.,~,~ LS --~-~.h-~.~
Sheet flow is provided at inlet
.Water table depth is greater than 6 feet
wt. Minimum of 6" ponding is provided. .
-Cv`1 The ponded area will draw down in less than 4 days.
Planting soil infiltration rate is greater than 0.52 in/hr.
`T The in-situ sa'1 infiltration rate is greater than 0.2 inlhr.
Z~ A planting plan with spades and densities is provided. - eJa47r v~'~ti-~-t~ Q ~Z'uf~ ~, 32S ~k,~~ c.~~
Muldi layer is specified in plans.
"'CwL Planting sal meets minimum sal specfications (NCDENR Stonnwater Best Management
Practices Manual, Apnl 1999)
~~ Plan details for the bioretention area provided.
'two Plan details for the inlet and outlet are provided.
An operation and maintenance agreement signed and notarized by the responsble party is provided. ~-ItJ//~
~~
t("~!~-~ ~~Ll~ Phone Number.
basin this worksheet applies to:
Please note that underdrains beneath the planting soil are acceptable in the Piedmont and Mountains