20081658 Ver 1_More Info Received_20090925

WITHERS 03 RAVENEL
ENGINEERS I PLANNERS ISURVEYORS
September 25, 2009
Ms. Amy Chapman
NC-DWQ
2321 Crabtree Boulevard, Suite 250
Raleigh, North Carolina 27604
RE: Mike & Janet Rogers Residence
305 Champions Point Way
Cary, North Carolina, 27513
Ms. Chapman:
o$- MOSS ua.
sFP ?
` 2 5 2009
WFT DERR - WATER QUALITY
S AV STQRA( ATER BRANCH
We are providing this letter in response to your Request For More Information provided on
September 2, 2009 regarding DWQ Project #2008-1658v2. We have included the
information requested in your letter and we offer the following information in response to
the comment proved:
1. We have included a completed Infiltration Basin Supplement Form and all items on
the checklist not provided with the previous submittal.
2. We have indicated the roof area to be treated by the infiltration basin. The area
being treated (625 sgft) is fully accommodated in the proposed infiltration basin
design and exceeds the area of the proposed impacts (447 sqft).
3. We have included more detail regarding the hydraulic device that will convey the
stormwater runoff from the rooftop to the basin including the proposed bypass
overflow from the side of the grit chamber into a bypass swale.
4. We have removed the vegetated area upslope of the infiltration basin. The
proposed basin is over the area of suitable soil which runs at a consistent depth
below the surface. We have also located the basin as far as possible from the
proposed structure to minimize any adverse impacts.
5. We have indicated the surface of the basin will be planted with grass.
6. We have included a CD with the proposed stormwater plan in TIFF format.
Please advise should you require additional information in support of this application. We
appreciate your time and assistance regarding this matter.
Sincerely,
WJTHERS cS? RAVENEL, INC
Bertoncino, PE
Attachments
Permit No
(to be provided by DWQ)
4
.-?R
STORMWATER MANAGEMENT PERMIT APPLICATION FORM Ma
WDENR 401 CERTIFICATION APPLICATION FORM
INFILTRATION BASIN SUPPLEMENT
This form must be tilled out, printed and submitted.
The Required Items Checklist (Part III) must be printed, filled out and submitted along with all of the required information.
I. PROJECT INFORMATION
Project Name Rogers Residence - 412 Prestonwood
Contact Person Jason Bertoncino
Phone Number 919-535-5174
Date 22-Sep-09
Drainage Area Number 1
II. DESIGN INFORMATION
Site Characteristics
Drainage area 625.00 ft2
Impervious area 625.00 ftz
Percent impervious 1.00 %
Design rainfall depth 1.00 in
Peak Flow Calculations
1-yr, 24-hr rainfall depth 2.83 in
1-yr, 24-hr intensity 012 in/hr OEP n4fi.4 (5 sue, irvTtt7u5 i TY 4-73,-.,/
++?
Pre-development 1-yr, 24-hr discharge 0.00 ft3lsec lxS`? i7 iArv i IZvn? 6FF

Post-development 1-yr, 24-hr discharge
0.00
ft3/sec ?JVLIi?LL AZt-Ay lUU.1n?tTLS

Pre/Post 1-yr, 24-hr peak flow control
0.00
ft3lse Fr?L _
L
Storage Volume: Non-SA Waters
Minimum design volume required 52.00 ft 3
Design volume provided 52.00 ft3 OK for non-SA waters
Storage Volume: SA Waters
1.5" runoff volume ft 3
Pre-development 1-yr, 24-hr runoff volume ft3 N i N
Post-development 1-yr, 24-hr runoff volume ft3
Minimum required volume ft3
Volume provided ft3
Soils Report Summary
Soil type Silty Loam
Infiltration rate 0.63 in/hr
SHWT elevation 306.00 fmsl
Basin Design Parameters
Drawdown time 0.59 days OK
Basin side slopes 3.00 :1 OK
Basin bottom elevation 308.50 fmsl OK
Storage elevation 309.00 fmsl
Storage Surface Area 70.00 ftz
Top elevation 309.75 fmsl
Basin Bottom Dimensions
Basin length ft Mint .Ab T?p'6., wj
Basin width ft
Bottom Surface Area 70.00 ft2
Form SW401-Infiltration Basin-Rev.4 Parts I. & II. Design Summary, Page 1 of 2
Permit No.
(to be provided by DWQ)
Additional Information
Maximum runoff to each inlet to the basin? 0.14 ac-in OK
Length of vegetative filter for overflow 92.00 ft OK
Distance to structure 30.00 ft OK
Distance from surface waters 92.00 ft OK
Distance from water supply well(s) ft ---ip "br- PQi i;SEr -7
Separation from impervious soil layer ft --> NUT y--vL,;v7
Naturally occuring soil above shwt 2.00 It OK
Bottom covered with 4-in of clean sand? Y (Y or N) OK
Proposed drainage easement provided? y '- (Y or N) OK
Capures all runoff at ultimate build-out? y (Y or N) OK
Bypass provided for larger storms? y (Y or N) OK
Pretreatment device provided Grit Chamber
N?tlY7!iRfl t7ftA A89Ap'PO®
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Form SW401-Infiltration Basin-Rev.4 Parts I. & II. Design Summary, Page 2 of 2
Permit No.
(to be provided by DWQ)
III. 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.
Pagel Plan
In'tials Sheet No.
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 infiltration basin showing:
- Bypass structure,
- Maintenance access,
- Basin bottom dimensions,
- Basin cross-section with benchmark for sediment cleanout,
- Flow distribution detail for inflow,
- Vegetated filter, and
- Pretreatment device.
3. Section view of the infiltration basin (1" = 20' or larger) showing:
- Pretreatment and treatment areas, and
- Inlet and outlet structures.
4. A table of elevations, areas, incremental volumes & accumulated volumes to verify the volume provided.
J?
?/ 5. A soils report that is based upon an actual field investigation, soil borings, and infiltration tests. The
?? results of the soils report must be verified in the field by DWQ, by completing & submitting the soils
investigation request form. County soil maps are not an acceptable source of soils information.
6. A construction sequence that shows how the infitlration basin will be protected from sediment until the
entire drainage area is stabilized.
7. The supporting calculations.
8. A copy of the signed and notarized operation and maintenance (0&M) agreement.
"J 9. A copy of the deed restrictions (if required).
Form SW401-Infiltration Basin-Rev.4 Page 1 of 1 Part III. Required Items Checklist, Page 1 of 1
0
RIVE NEW LONDONDALE D ~ 0
Q ~ SOLID COVER ROOF AREA TO E TREATED = 625 SF Z
ID COVER H U
G4 STORMWATER STORAGE AREA 6" PVC ROOF DRAIN 1"VOLUME CALCULATION: ~ E
a~ o
J~ 18'°x18" HDPE ~ ~ VOLUME T B TREATED = 625 SF x (1")(%2) = 52 CF W
~ COLLECTION BOX ~ r
0 & GRIT CHAMBER ~9 REQUIRED STORMWATER STORAGE AREA: ~
4~ DECORATIVE H ~
Q TOP OF BOX MAX. WATER REQUIRED AREA = 52 CF 10.75' DEPTH = 70 SF 3~~ 6,, Top ~
w~ EL=310.00 SURFACE ELEV=309.75 GRASS 3''
c, EDGE OF BOX ELEVATION=309,75 0.75' 12n of ~ ~ _ ~
TO BYPASS SWALE - EL-310.00 FV~31o k CHECK CAPACITY OF 6" PVC ROOF DRAIN LEADER: _
~ EDGE OF BOX ELEVATION=309.25 1° _ '~S Q(10) =CIA =(1,0)(7.22 "IHR)(625 SF 143560 SFIAC) = 0.10 CFS d
~ EL-309.00 5 x , .gyp 'y. ,Tiv~ .i I N
a TO STORAGE AREA. •:.x:~~;,,~.1,..,;'a~~ a°: ry::. .y/ AS n r ,,x:~ ~•4: EL-308.50 .Q
SEE COLLECTION BOX 0 T CHAMPIONS POINT WAY n ~ 5 E CAPACITY OF 6°' PVC 1.0 SLOPE = 0.56 CFS OK W
~ DETAIL THIS SHEET ~L ,7 A~ R o9 ~ ' W o
~I , 3 ~ V~ V~ ~ ti CLEAN SAND ~ Q
A 24 L L P F 6 PVC R F V~ ~ oo R S E S~ STO CHECK FLOW DEPTH OVER WEIR = ~ ~ z ~p ~ ~
~ MINIMUM 1 MINIMUM m ~ DRAIN LEADER 2 PERMEABLE GEO Q ~ Ta ,2 2~ To ~ `G M~aT 9.5 W
o~ ~ UNDISTURBED TEXTILE FABRIC , 3 0 3~~~ F ~RFq R Q=CLH s
T V A E E R 0.11 CFS=(3)(1")H7.~
EL P R T SEASONAL HIGH I ~ E E H=0.11' =1.3" < 3"PROVIDED OK
1~ T WATER TABLE P E
TR
LTI ETIL T STORAGE AREA CALCULATIONS
Q

1 Z
W

z W
o ~
1 STORMWATER ~ Q
STORAGE AREA ~ ~
s. 70.0 S Ft Q
q 625 SQ. FT. IMPERVIOUS
TREATMENT
~ uJ
STORMWATER I-'
'•1 1
~ EIP STORAGE AREA ~
CHAMPION'S POINT WAY
VARIABLE WIDTH R/W ~ ~ ' ° ,
o ;
OVERFLOW MH® EIP Ip-^
SWALE
COLLECTIO
BOX
rah ~ 50' NEUSE RIVER Z
30' COMBINED \ ,i / RIPARIAN BUFFER J
SANITARY SEWER AND yJ~ DRAINAGE EASMENT ` si~`~ EIP ~
rs / U
8"HDPE ~ / TOP BANK O
JV eQ jog .CULVERT J ~ ~ TURKEY CREEK
ROOF AREA ~
v 625 SQ.FT. . f ~ ~ N~ W
6 PVC ROOF , . ~ r' X ~ PCC SPORTS AND V
DRAIN LEADER ~ ` RECREATION SERVICES, INC.
,~,~•.~....T~..,a ,f'~ 'f W
i~, 447 SQFT IMPERVIOUS
i i~°,,` ENCROACHMENT ~ z
NIP W o
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it / ' des i`
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0
GRAPHIC SCALE
50 p 25 50 100
\ ~
o \ ~ W 1 inch = 50 ft.
i \ ~ N \ ~
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\ I o o \ \ ~ COP cn4~O0 Q CONSTRUCTION NOTE:
a r I - N m
N \ \ N \ \ a
~ \ \ f o TC E i STORMWATER STORAGE AREA SHALL BE PROTECTED ~ ~ 3 ~ DD
m \ \ o \ \ FC ~3o~u FROM RUNOFF UNTIL ENTIRE SITE IS STABILIZED.
N
~ \ \ ° \ \ \ 4 \ \ ~ , m
\ \ ~
\ o D \ \ \ c ~ y POOL DECKI~URFACE AREA
m \ ~ / i \ \ / , N \ 318 SgFt
\ \ \ ~ / a
i \ \ ~ ' ~ ' x \
\ \ \ \ `J
/ \ \ \ \ ~ ~ 'J o_
\ \ RETAINING WALL ~ / 0ao®o08A0A0®BO°°0
w \ \ \ 129 SgFt m \ \ \ 0 1. eqo®,®,Q~~~ooCARp~~y°°
a` ~ \ \ \
N \ \ \ \ \ o ~o aFESSJa a o~ e
a - \ \ , a \ \ GRAPHIC SCALE oQ ° s °
8 ~ ~~nA w e °
\ \ \ \ / / 10 0 5 10 20
\ 31
g \ o RE-VEGETATION \ \ \ 0 1 inch = 10 ft. pp ~ OOOOOtltl0° O~
\ \ \ LANDSCAPE ARE ®a®®~ 040000E6 a °
\ \ \ \ 955 SgFt \ \ 309 \ z
w r r
Y