SW7080922_HISTORICAL FILE_20081028

STORMWATER DIVISION CODING SHEET
POST -CONSTRUCTION PERMITS
PERMIT NO.
DOC TYPE
❑ CURRENT PERMIT
❑ APPROVED PLANS
I HISTORICAL FILE
(❑ COMPLIANCE EVALUATION INSPECTION
DOC DATE
YYYYMMDD

vICIQM&CREED
October 27, 2008
Scott Vinson
NCDENR — DWQ
943 Washington Square Mall
Washington, NC 27889
OCT 2 8 2008
ENGINEERS
SURVEYORS
P L A N N E R S
M&C 04135-0001 (40)
RE: River Dunes Riverside Village and Fire Station Area - SW7080922
High Density Stormwater Permit
Request for Additional Information
Dear Mr. Vinson:
In response to your request for Additional Information dated October 7, 2008, we
have included below our responses in red along with two copies of attached
plans and submittal forms.
1. A site visit was conducted today to verify soil and water table conditions. It
was difficult to determine the elevations of the neighboring wetlands with the
additional fill material and the ongoing grading work. The existing contour
elevations for both areas around the wetlands are not given on the Grading
and Drainage Plan sheets C 3.1. The elevations of the wetlands can play a key
role in helping to determine the SHWT. Please include the contour elevations
beyond all of the infiltration basins and down into the wetlands for both the
Riverside Village and Fire Station Area.
Response: We have included spot grades around the wetlands on the C3.1
sheets for both the Fire Station Area and Riverside Village.
2. The Fire Station Infiltration Basin supplement form has inconsistent surface
areas for the Storage SA and Bottom SA that do not match the calculations or
plans. The surface areas given on the supplement forms for the Riverside
Venture IV Building Village basins are also inconsistent with there corresponding calculations and
plans.
1730 Varsity Drive Response: We have corrected the supplement forms to match the calculations
Raleigh, NC 27606 and plans.
3. The calculation page 1 of 2 for basin RS-3 is missing from the application
919.233.8091 package. Please provide.
Response: We have included this calculation page.
Fax [phone]
www. rcki screed. con,

Mr. Scott Vinson
October 27, 2008
Page 2 of 3
4. The Fire Station calculation pages 2 & 3 are labeled for the "RV & Boat Storage
Area". Please confirm that this is just a typo and that the calculations are for
the Fire Station area as they appear to be.
Response: This was just a typo and we have included the revised calculations.
5. There is a maximum 2ac-in volume allowed per inlet into each infiltration
basin and the Riverside Village basins each have 5ac-in volume coming into
one inlet each. Please provide additional inlets such that each will have 2ac-in
or less volume and provide labels for each inlet and corresponding calculations
to show how much volume each inlet has.
Response: In our previous phone conversations as well as the Express Review
pre-app meeting, we discussed the use of a flow distribution device along the
infiltration basin bottom in lieu of additional inlets. We have shown these flow
distribution devices on the plans and updated our narrative to include this
design element.
6. As discussed in our Express meeting, there needs to be a flow distribution
device for Basins RS-2 & RS-3 to evenly distribute the runoff coming in
throughout the whole basin. Please also provide a cross section detail of the
proposed device.
Response: See response from above. We have also added a flow distribution
device in basin RS-1 since there is greater than 2 ac-in runoff volume entering
the basin at the inlet.
7. Please delineate and include the labeling for any CAMA wetlands, buffers,
mean high water lines, surface waters, etc. on the overall site & drainage plans
for Riverside Village to help show location and/or distance from surface
waters.
Response: We have included these callouts in the site and grading and
drainage plans, as well as added dimensions from the basins to the wetlands.
For both Riverside Village and Fire Station Area, waters designated as surface
waters are located a far enough distance away that they fall out of the captured
plan view.
8. Please clearly delineate the drainage areas for each of the three infiltration
basins in Riverside Village. Although there are Flow arrows it is difficult to
read the drainage patterns and any contours or elevations with the hatching
shown. Please revise the Grading & Drainage Plan sheet C3.1 to help clearly
show the Flow direction of runoff by including additional proposed elevations,
pipe inverts, and the labeling for drop inlets, curb cuts, catch basins inverts,
etc..
Response: We have added the drainage areas with labels along with additional
v�MgQM&CREED

Mr. Scott Vinson
October 27, 2008
Page 3 of 3
labels for the stormwater devices. We have also increased the size of the flow
arrows.
9. The narrative describes pretreatment with the use of a sump in the bottom of
the catch basins, however the detail of the catch basins do not show this. Please
revise the catch basin detail to have this sump of at least 1 foot deep.
Response: We have included new details for the catch basins showing the
sump.
10. Please provide the 25%, additional information fee associated with the
Express Stormwater Review Program of $1000.00 by check made payable to
"NC DENR".
Response: River Dunes Corporation will be sending this check separately via
mail or courier.
I trust that this information will be sufficient for your review. If you require
clarification or additional information, please do not hesitate to contact•me.
Thank you.
Sincerely,
McKIM & CREED, P.A.
Curtis M. Blazier, PE
Project Manager
Enclosures
cc: Ed Mitchell, River Dunes Corporation
'MqQM&CREED

ral
awl
Y
Mr. Ed Mitchell, President
River Dunes Corporation
416-A Pollock Street
New Bern, NC 28560
Dear Mr. Mitchell:
Michael F. Easley, Governor
William G. Ross Jr- Secretary
North Carolina Department of Environment and Natural Resources
:Van W. Klimek, P.E. Director
Division of Water Quality
October 7, 2008
Subject: Stormwater Review SW7080922
River Dimes Marina & Residential Development
Riverside Village & Fire Station Area
Pamlico County
This office received a Coastal Stormwater permit application and plans for the subject project on
September 23, 2008. A preliminary review of the project indicates that before a State Stormwater permit can be
issued the following additional information is needed.
1. A site visit was conducted today to verify soil and water table conditions. It was difficult to determine the
elevations of the neighboring wetlands with the additional fill material and the ongoing grading work. The
existing contour elevations for both areas around the wetlands are not given on the Grading and Drainage
Plan sheets C 3.1. The elevations of the wetlands can play a key role in helping to determine the SHWT.
Please include the contour elevations beyond all of the infiltration basins and down into the wetlands for
both the Riverside Village and Fire Station Area.
2. The Fire Station Infiltration Basin supplement form has inconsistent surface areas for the Storage SA and
Bottom SA that do not match the calculations or plans. The surface areas given on the supplement forms
for the Riverside Village basins are also inconsistent with there corresponding calculations and plans.
3. The calculation page 1 of 2 for basin RS-3 is missing from the application package. Please provide.
4. The Fire Station calculation pages 2 & 3 are labeled for the "RV & Boat Storage Area". Please confirm
that this is just a typo and that the calculations are for the Fire Station area as they appear to be.
5. There is a maximum lac -in volume allowed per inlet into each infiltration basin and the Riverside Village
basins each have Sac -in volume coming into one inlet each. Please provide additional inlets such that each
will have 2ac-in or less volume and provide labels for each inlet and corresponding calculations to show
how much volume each inlet has.
6. As discussed in our Express meeting, there needs to be a flow distribution device for Basins RS-2 & RS-3
to evenly distribute the runoff coming in throughout the whole basin. Please also provide a cross section
detail of the proposed device.
7. Please delineate and include the labeling for any CAMA wetlands; buffers, mean high water lines, surface
waters, etc. on the overall site & drainage plans for Riverside Village to help show location and/or distance
from surface waters.
NorthCarolina
,lVatrrrally
North Carolina Division of Water Quality Washington Regional Office Phone [phone] FAX[phone] Customerservice
Internet: h2o.encslale.nc.us 943 Washington Square Mall, Washington. NC 27899 1-877-623-6748

8. Please clearly delineate the drainage areas for each of the three infiltration basins in Riverside Village.
Although there are flow arrows it is difficult to read the drainage patterns and any contours or elevations
with the hatching shown. Please revise the Grading & Drainage Plan sheet C3.1 to help clearly show the
flow direction of runoff by including additional proposed elevations, pipe inverts, and the labeling for, drop
inlets, curb cuts, catch basins, etc..
9. The narrative describes pretreatment with the use of a sump in the bottom of the catch basins, however the
detail of the catch basins do not show this. Please revise the catch basin detail to have this sump of at least
I foot deep.
10. Please provide the 25% additional information fee associated with the Express Stormwater Review
Program of $1000.00 by check made payable to "NC DENR".
The above requested information must be received in this office prior to October 14,. 2008'or your
application will be returned as incomplete. The return of this project will necessitate resubmittal of all required
items including the application fee. If you need additional time to submit the required information, please mail
or fax your request for time extension to this office at the Letterhead address.
You should also be aware that the Stormwater Rules require that the permit be issued prior to any
development activity. Construction without a permit is a violation of 15A NCAC 21-I.1000 and North Carolina
General Statute 143-215.1 and may result in civil penalties of up to $10,000 per.day..
Please reference the Stormwater Project Number above on all correspondence. If you have questions, please
feel free to contact me at [phone].
Sincerely,
Scott Vinson
Environmental Engineer
Washington Regional Office
cc: Curtis Blazier, PE McKim & Creed
Washington Regional Office

5W7oF6�2z
STORMWATER MANAGEMENT PERMIT APPLICATION FORM (SWU-101 VER. 03.27.08)
PART III PROJECT INFORMATION
ITEM 9 -DRAINAGE AREAS
RIVER DUNES MARINA AND RESIDENTIAL DEVELOPMENT - RIVERSIDE VILLAGE AND FIRE STATION AREA
for
RIVER DUNES CORPORATION
Drainage Area
1
2
3
4
Basin Information
RS-1
RS-2
RS-3
FS-1
Receiving Stream Name
Gum Thicket
Creek
Gum Thicket
Creek
Gum Thicket
Creek
Tar Creek
Totals
Receiving Stream Class
SA NSW
SA NSW
SA NSW
SA NSW
Drainage Area (Square Feet)
137,832
213,771
270,338
63,784
685,725
Existing Impervious Area (Square Feet)
0
0
0
0
0
Proposed Impervious Area (Square Feet)
48,300
99,292
138,663
35,631
321,886
% Impervious Area (Total)
35
46
51
56
47
Impervious Surface Area (Sq. Feet)
On -Site Buildings *
2,000
59,000
98,000
10,650
169,650
On -Site Streets
15,340
34,075
34,809
0
84,224
On -Site Parking (street)
1,296
0
0
23,056
24,352
On -Site Sidewalks
3,744
6,217
5,854
1,925
17,740
Other (tennis courts)
25,920
0
0
0
25,920
Total (Square Feet)
48,300
99,292
138,663
35,631
321,886
* Impervious surface areafor on -site buildings in RS-2 and RS-3 includes driveways and is a maximum amount.

Red mangles at the upper right hand comer indicate design comments
Please complete the yellow shaded items.
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
401 CERTIFICATION APPLICATION FORM
INFILTRATION BASIN SUPPLEMENT
This form must be filled out, printed and submitted.
The Required Items Checklist (Part 111) must be printed, filled out and submitted along with all of the required information.
Project Name
Contact Person
Phone Number
Date
Drainage Area Number
River Dunes Marina 8 Residential
Mr. Ed Mitchell
ILA. DESIGN.INFORMATION,'
Site Characteristics
Drainage area
137,832
f?
Impervious area
48,300
Ill
Percent impervious
35
%
Design rainfall depth
3.00
in
Peak Flow Calculations
1-yr, 24-hr runoff depth
3.48
in
1-yr, 24-hr intensity
0.15
irvhr
Pre -development l-yr, 24-hr runoff volume
1,998.57
ft"Isec
Post -development 1-yr, 24-hr runoff volume
14,604.87
ftclsec
Pre/Post l-yr, 24-hr peak flow control
12,606.30
It3lsec
Storage Volume: Nori Waters
Minimum design volume required
12,590
W
Design volume provided
14,204
It
•
Storage Volume: SR Waters
1-yr, 24-hr rainfall depth
in
Pre -development 1-yr, 24-hr runoff
fill
Post -development 1-yr, 24-hr runoff
ffc
Minimum volume required
fts
Volume provided
its
Soils Report Summary
Soil type
Loamy Sand
Infiltration rate
1.30
inlhr
SHWt elevation
1.00
fmsl
Basin Design Parameters
Drawdown time
0.49
days
OK
Basin side slopes
3.00
:1
OK
Basin bottom elevabon
100
fmsl
^v
Storage elevation
5.00
fmsl
Storage SA
8,082
flz
Top elevation
5.75
fmsl
G��4ti
Basin Bottom Dimensions
Basin length
113.00
It
Basin width
72.00
ft
Bottom SA
11,903.00
ffz
Additional Information
_
Total runoff volume captured by basin
5.00
ac-in
Maximum of 2 acre -inches allowed
Length of vegetative filter for overflow
50.00
ft
OK
Distance to structure
NIA
It
OK
Distance from surface waters
50.00
ft
OK
Distance from water supply wells)
NIA
ft
OK
Separation from impervious soil layer
0.00
It
OK
Naturally occudng soil above shot
2.00
It
OK
.
Bottom covered with 4-in of clean sand?
y
(Y or N)
OK

Red triangles at the upper right hand comer indicate design comments
Please complete the yellow shaded items.
• STORMWATER MANAGEMENT PERMIT APPLICATION FORM
401 CERTIFICATION APPLICATION FORM
INFILTRATION BASIN SUPPLEMENT
This form must be filled out, printed and submitted.
The Required Items Checklist (Part III) must be printed, filled out and submitted along with all of the required information.
Contact Person
Phone Number
Date
Drainage Area Number
II.. DESIGN'INFORMATION
Site Characteristics
911912008
Drainage area
213,771
fits
Impervious area
99,292
fit?
Percent impervious
46
Design rainfall depth
3.00
in
Peak Flow Calculations
1-yr, 24-hr mnoff depth
3.48
in
1-yr, 24-hr intensity
0.15
inlhr
Pre -development l-yr, 24-hr runoff volume
3,099.68
f Isec
Post -development 1-yr, 24-hr runoff volume
29,014,94
ff'Isec
Pre/Post l-yr, 24-hr peak flow control
25,915.26
ft isec
Storage Volume: Non -SR Waters
Minimum design volume required
25,013
It,
Design volume provided
27,823
fit,
.Storage
Volume: SR Waters
1-yr, 24-hr rainfall depth
in
Pre -development 1-yr, 24-hr runoff
It,
Post -development 1-yr, 24-hr runoff
ft,
Minimum volume required
It,
Volume provided
rya
Soils Report Summary
Soil type
Loamy Sand
Infiltration rate
1.30
in/hr
SHWf elevation
1.00
first
Basin Design Parameters
Drawdown time
0.49
days
OK
Basin side slopes
3.00
:1
OK
Basin bottom elevation
3,00
fmsl
OK
Storage elevation
5,00
fmsl
Storage SA
15,964
ftz
Top elevation
5.75
final
_
Basin Bottom Dimensions
Basin length
233.00
It
C, IKl
Basin width
123.00
ff
Bottom SA
6,436.00
ff
Additional Information
Total runoff volume captured by basin
5,00
ac
t, ved
Length of vegetative filter for overflow
50.00
$
OK
Distance to structure
NIA
It
OK
Distance from surface waters
50.00
It
OK
Distance from water supply well(s)
NIA
It
OK
Separation from impervious soil layer
0.00
It
OK
Naturally occunng soil above shwt
2.00
It
OK
•
Bottom covered with 4-in of clean sand?
y
(Y or N)
OK

Red triangles at the upper right hod comer indicate design comments
Please complete the yellow shaded items.
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
401 CERTIFICATION APPLICATION FORM
INFILTRATION BASIN SUPPLEMENT
This form must be filled out, printed and submitted.
The Required Items Checklist (Part III) must be printed, filled out and submitted along with all of the required information.
Project Name
Contact Person
Phone Number
Date
Drainage Area Number
IL. DESIGNINFORMATION
Site Characteristics
River Dunes Marina 8
[phone]
9/1912008
Drainage area
270,338
its
Impervious area
138,663
rye
Percent impervious
51
Design rainfall depth
3.00
in
Peak Flow Calculations
1-yr, 24-hr runoff depth
3.48
in
1-yr, 24-hr intensity
0.15
inthr
Pre -development 1-yr, 24-hr runoff volume
3,919.90
ry3lsec
Post -development l-yr, 24-hr runoff volume
40,110.91
fti
Pre/Post l-yr, 24-hr peak flow control
36,19101
ry3lsec
Storage Volume: Non -SR Waters
Minimum design volume required
34,578
rya
Design volume provided
34,971
rya
®
Storage Volume: SRWalers
1-yr, 24-hr rainfall depth
in
Pre -development 1-yr, 24-hr runoff
its
Post -development 1-yr, 24-hr runoff
ft3
Minimum volume required
It,
Volume provided
ft3
Soils Report Summary
Soil type
Loamy Sand
InfilVatlon rate
1.30
inlhr
SHWT elevation
1.00
mist
Basin Design Parameters
Drawdown time
0.55
days
OK
Basin side slopes
3.00
t1
OK
Basin bottom elevation
3.00
most
OK
Storage elevation
4.50
fall
Storage SA
25,095
fe
Top elevation
5,50
Imsl
Basin Bottom Dimensions
Basin length
304.00
it
Basin vndlh
142.00
It
Bottom SA
21,547.00
file
Additional Information
Total runoff volume captured by basin
5.00
ac-in
Maximum of 2 acre -inches allowed
Length of vegetative filler for overflow
50.00
it
OK
Distance to structure
NIA
ft
OK
Distance from surface waters
50.00
ff
OK
Distance from water supply well(s)
NIA
ry
OK
Separation from impervious soil layer
0.00
ry
OK
Naturally occudng soil above shwt
Bottom covered with 4-in of clean sand?
2.00
It
(Y or N)
OK
OK
y

Permit No.. S c1,(`JOSoY ..�_
(to be provided by DWQ)
_
AO
04 WATFA
STORMWATER MANAGEMENT PERMIT APPLICATION FORM s�
401 CERTIFICATION APPLICATION
FORM
®NCDENR
INFILTRATION BASIN
SUPPLEMENT
This form must be filled 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,".P.ROJECT<INFORMATION'' "
I` .
Project Name
River Dunes Manna and Residential Development- Harbor Village V
Contact Person
Mr. Ed Mitchell
Phone Number
[phone]
Date
911512008
Drainage Area Number
FS-1
II;,DESIGN114FORMATION .
Site Characteristics
Drainage area
63,784.00
it'
Impervious area
35,631.00
ft?
Percent impervious
0.56
%
Design rainfall depth
3.00
in
Peak Flow Calculations
1-yr, 24-hr runoff depth
3.48
in
1-yr, 24-hr intensity
0.15
infhr
Pre -development 1-yr, 24-hr runoff volume
925.00
ft3/sec
Post -development 1-yr, 24-hr runoff volume
10,225.00
ft/sec
Pre/Post 1-yr, 24-hr peak flow control
9,300.00
ft3/sec
Storage Volume: Non -SR Waters
Minimum design volume required
8,814.00
ft'
*esign volume provided
9,756,00
ft' OK for non -SR waters
Storage Volume: SR Waters
1-yr, 24-hr rainfall depth
in
Pre -development 1-yr, 24-hr runoff
ft,
Past -development 1-yr, 24-hr runoff
ft'
Minimum volume required
It"
Volume provided
ft,
Soils Report Summary
Soil type
SM
Infiltration rate
1.30
in/hr
SHWT elevation
1.20
fmsl
Basin Design Parameters
Drawdown time
0.75
G
days
Basin side slopes
3.00
2,N4
:1 �oIN
Basin bottom elevation
3.20
fmsl
Storage elevation
4.20
fmsl C'a\`"�
Storage SA
9,493.00
l 7
Top elevation
5.50
fmsl
Basin Bottom Dimensions
Basin length
190.30
ft n'�
Basin width
51.00
ft fk_r
Bottom SA
10,424.00
ft2 Oct 2,) f
Form SW401-Infiltration Basin-Rev.2
Parts I. 8 ll. Design Summary, Page 1 of 2

Permit
(to be provided by DWQ)
Additional Information
Total runoff volume captured by basin
Length of vegetative filter for overflow
istance to structure
islance from surface waters
Distance from water supply well(s)
Separation from impervious soil layer
Naturally occuring soil above shwl
Bottom covered with 4-in of clean sand?
Proposed drainage easement provided?
Capures all runoff at ultimate build -out?
Bypass provided for larger storms?
Pretreatment device provided
•
11
2.45
ac-in
50.00
ft
NIA
ft
50.00
It
NIA
ft
NIA
ft
2.00
(t
NIA
(Y or N)
Y
(Y or N)
Y
(Y or N)
NIA
(Y or N)
Y
Maximum of 2 acre -inches allowed
OK
OK
OK
OK
OK
OK
OK
OK
OK
OK
Form SW401-Infiltration Basin-Rev.2 Pans I. is 11. Design Summary, Page 2 of 2

River Dune§Riverside Village - proposed flow distribution device details
Subject: River Dunes Riverside Village - proposed flow distribution device details
From: "Curtis M 131azier" <[e-mail]>
Date: Thu, 16 Oct 2008 16:53:11 -0400
To: "Scott Vinson' <Scott. VinsonCncmaiLnct>
Scott,
Attached is a PDF of a detail and plan views of basins with the proposed flow distribution
device. I have listed on the plan sheets for the basins their design volumes and the ac-in runoff
volume. I re -calculated some of our numbers and these ac-in figures are higher than what we
previously submitted for these two infiltration basins.
Please take a look at this design and comment and reply back to me. We are still on target to
submit for Tuesday, so if you could get back to me by sometime tomorrow AM, that would be
good.
I also want to ask you about the wetlands elevations. Thanks for your assistance, Scott. S
Curtis M. Blazier, PE
Project Manager
MCIQM&CREED
ENGINEERS SURVEYORS PLANNERS
1730 Varsity Drive, Suite 500
Raleigh, NC 27606
919.233.8091
919.233.8031 fax
htt p://www. nrokimereed.cwm
This e-mail and any files transmitted with it are confidential
and intended solely for the use of the individual or entity to
whom they are addressed. If you have received this e-mail in
error please notify the system manager. Please note that any
views or opinions presented in this e-mail are solely those of
the author and do not necessarily represent those of the
company. Finally, the recipient should check this e-mail and
any attachments for the presence of viruses. The company
accepts no liability for any damage caused by any virus
transmitted by this e-mail.
Comcnt-Description: Riverside Flow Dist. Details.pdf
Riverside —Flow Dist. Details.pdfContent-Type: application/octet-stream
Content -Encoding: base64
1 of 1 10/23/2008 10:13 AM

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TRATION BASIN RS-2 .
TIRED = 25,037 CU FT
IDED = 26,127 CU FT
OM EL = 3.00 FMSL
AGE EL = 5.00 FMSL
EL = 5.75 FMSL
= 1.00 FMSL
rvld Vjy/zreU
%Ylc�
�6 iA/L
SCALE: 1"=40' (Horiz.)
INFlLTRATION BASIN RS-2 STORMWATER DESIGN
RIVERSIDE VILLAGE B-26
Rde North Cad4w

Cnf- uX,P Va<oiyE=
-/.%3 a --;A
„ 50' 0 50' 100'
NORTH SCALE: 1"=50' (Horiz.)
`
INFILTRA71ON BASIN RS-3 STORMWATER DESIGN
l no w+y u«, an. em
aa�'facriu-,aoi. va piolxu-ewe
RIVERSIDE VILLAGE
B-3b
R: Nate Cadfna

I 1 li I 4- - /1,
INFILTRATION BASIN RS-1 LS-1 /
REQUIRED = 12,590 CU FT (� L = 20 FT
PROVIDED = 14,204 CU FT / TOP LIP EL. 5.00 FT
BOTTOM EL = 3.00 FMSL SEE DEE TAIL —SHEET D4
5
STORAGE EL = 5.00 FMSL s 5 4+ 5
TOP EL = 5.75 FMSL
SHWT = 1.00 FMSL 7 +
AP 0 059 V e 3.41 - ikt +4.5
31 ■ ■
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`v�I n<B4&CREM River Dunes Riverside Village
1730 Varsity,o'h Cor ro 6 Infiltration Basin IRS-1
Raleigh, North 3-80 1 27606
Phono: [phone]. Fax: [phone] Stormwater Design
www.mck mcreed.com
e _
7
40
NORTH
0 30'
SCALE: 1"=30' (Horiz.)
OAM OOIOeLe 21, 2000
4O PPOA P 0,1101-0002
MAW me
ems
aram we
PRM UMw WL
SCALE
L
NA

50' 0 50' 100'
NORTH SCALE: 1"=50' (Horiz.)
�.. (nrpss.cn, rs <ne�sarav
Ral North C�dina
INFILTRATION BASIN RS-3 STORMWATER DESIGN
RIVERSIDE VILLAGE

40' f f 1*'-a 40' SD'
SCALE: 1"=40' (Horiz.)
INFILTRATION BASIN RS-2 STORMWATER DESIGN
°"°" `"°'. `�"•""°�'
RIVERSIDE VILLAGE
Rdd North CaroMo

lit
INFILTRATION BASIN RS-1
REQUIRED = 12,590 CU FT
PROVIDED = 14,204 CU FT
BOTTOM EL = 3.00 FMSL
STORAGE EL = 5.00 FMSL
TOP EL = 5.75 FMSL
SHWT = 1.00 FMSL
g
r4 oW
Sox
V -j.? A--ijE
_4`
- LS-1
L = 20 FT
TOP OF LIP EL. 5.00 FT
_ SEE DETAIL - SHEET D4
3
40
NORTH
V ^ qsa / 30' 0 30' 60
/// I
SCALE: 1"=30' (Horiz.)
N14M�4&CREED I River Dunes Riverside Village
770Raleigh, North Drive, Carolina Suite 500 I Infiltration Basin RS-1
Ph..:Nag) C-8091 27608 l
Phone: f919)233-8091, Fox [phone] Stormwater Design
www.mck mcr<ad.com
12+00
6
-7-
E
21, 00 0000C9BOIBcue
m

River Dunes - submittal extension request 1'or River Dunes - Riverside...
Subject: River Dunes - submittal extension request for River Dunes - Riverside Village and Fire Station Area
From: "Curtis M Blazier" <[e-mail]>
Date: Mon, 13 Oct 2008 10:13:56 -0400
To: "Scott Vinson" <[e-mail]>
CC: "L.yn Hardison" <[e-mail]>, "Adrianne Y E Coombes" <[e-mail]>
Scott,
I left you a voicemail earlier this morning regarding the Riverside Village and Fire Station Area
submittal for River Dunes. We would like to request an extension for submitting the responses
to your comments from last week. I don't know if we should just give you a date, or if you need
to look at the calendar and propose a couple dates. One of the main reasons for this extension
request is to be able to discuss with you a little bit more the flow distribution device for the
basin(s), related to these two comments:
5. There is a maximum lac -in volume allowed per inlet into each
infiltration basin and the Riverside Village basins each have
Sac -in volume coming into one inlet each. Please provide
additional inlets such that each will have 2ac-in or less volume
and provide labels for each inlet and corresponding calculations
to show how much volume each inlet has.
6. As discussed in our Express meeting, there needs to be a flow
distribution device for Basins RS-2 & RS-3 to evenly distribute
the runoff coming in throughout the whole basin. Please also
provide a cross section detail of the proposed device.
Per our phone conversation late last week, I know that you had said that you wouldn't be able
to meet with others at DWQ until sometime this week to discuss the half -pipe flow distribution
device running along the bottom of the basin and whether that would be acceptable for us to
use. As a possible alternative, I was wondering if we might be able to use a flow splitter box
before the runoff enters the basin and then create another inlet point for the basin.
Please call me to discuss when you get a chance. Thanks for your assistance.
Curtis M. Blazier, PE
Project Manager
M!4W&CREED
ENGINEERS SURVEYORS PLANNERS
1730 Varsity Drive, Suite 500
Raleigh, NC 27606
919.233.8091
919.233.8031 fax
hno://N% vw.mckiincr ed. wm
C&A
,re-
Oki,_k
1 A 0.
1 A,,, / • , 3
This e-mail and any files transmitted with it are confidential
and intended solely for the use of the individual or entity fo
whom they are addressed. If you have received this e-mail in
error please notify the system manager. Please note that any
views or opinions presented in this e-mail are solely those of
the author and do not necessarily represent those of the
company. Finally, the recipient should check this e-mail and
E

River Dunes - submittal extension request for River Dunes - Riverside...
any attachments for the presence of viruses. The company
accepts no liability for any damage caused by any virus '
transmitted by this e-mail.
2 of 2 IN13/2008 4:05 PM

w-
Re: rcer Dunes - submittal extension request for River Dunes - River...
Subject: Re: River Dunes - submittal extension request for River Dunes - Riverside Village and Fire Station Area
From: Scott Vinson <[e-mail]>
Date: Mon, 13 Oct 2009 16:15:01 -0400
To: Curtis M Blazier <Cl3lazieremckimcreed.com>
CC: Ed Mitchell <ed.mitehell t riverdunes.conl>
ron request is granted. The additional information for this project will be due on Tuesday., October
I will try and discuss the issue tomorrow of having greater than 2ac-in vol. at one inlet into an infil.basin if
there is good flow distribution and good erosion control measures provided. Regarding the proposal to have a
flow spl.itter box leading to multiple inlets is probably a better idea and may be easier to accept under the
existing guidance.
Thanks,
Scott
Curtis M Blazier wrote:
Scott,
I left you a voicemai.l earlier this morning regarding the Riverside Village and Fire Station Area submittal
for River Dunes. We would like to request an extension for submitting the responses to your comments from
last week. I don't know if we should just give you a date, or if you need to look at the calendar and propose
a couple dates. One of the main reasons for this extension request is to be able to discuss with you a little
bit more the flow distribution device for the basin(s), related to these two comments:
5. There is a maximum 2ac-in volume allowed per inlet into each
infiltration basin and the Riverside Village basins each have
Sac -in volume coming into one inlet each. Please provide
additional inlets such that each will have 2ac-in or less volume
and provide labels for each inlet and corresponding calculations
to show how much volume each inlet has.
6. As discussed in our Express meeting, there needs to be a flow
distribution device for Basins RS-2 a RS-3 to evenly distribute
the runoff coming in throughout the whole basin. Please also
provide a cross section detail of the proposed device.
Per our phone conversation late last week, I know that you had said that you wouldn't be able to meet with
others at DWQ until sometime this week to discuss the half -pipe flow distribution device running along the
bottom of the basin and whether that would be acceptable for us to use. As a possible alternative, I was
wondering if we might be able to use a flow splitter box before the runoff enters the basin and then create
another inlet point for the basin.
Please call me to discuss when you get a chance. Thanks for your assistance.
"Curtis M. Blazier, PE''
" Project Manager—
M'^C 'KIM/5/CREED
ENGINEERS SURVEYORS PLANNERS
1730 Varsity Drive, Suite 500
Raleigh, NC 27606
919.233.8091
919.233.8031 fax
http://www.mckimcreed.com <http://www.mckimcreed.com/>
This e-mail and any files transmitted with it are confidential
and intended solely for the use of the individual or entity to
whom they are addressed. If you have received this e-mail in
error please notify the system manager. Please note that any
views or opinions presented in this e-mail are solely those of
the author and do not necessarily represent those of the
company. Finally, the recipient should check this e-mail and
any attachments for the presence of viruses. The company
accepts no liability for any damage caused by any virus
transmitted by this e-mail.

Re: River Dunes - submittal extension request for River Dunes - River... Y' '
2 of 2 10/13/2008 4:15 PM

"0ct.11 200E 10:27AM
No.0520 P. 1/i
v
MCKIM&CREED
v
1730 Varsity Drive
Raleigh, NC 27606
Tel; 919,233.8091
Fax:[phone]
FACSIMILE TRANSMITTAL
DESIGNATED RECIPIENT; Scott Vinson FAX NO: [phone]
COMPANY; NCDENR DATE:. 10/13/08
SENDER: Curt Blazier TIME: 10:20 AM
NUMBER OF TRANSMISSION PAGES (Including cover sheet): 1
PROJECT NUMBER: 04135-0001 PROJECT NAME; River Dunes
® THIS IS YOUR ORIGINAL ❑ HARD COPY TO FOLLOW
COMMENT? "IF NOT CORRECTLY RECEIVED OR
SENDER AT 919.233.9091"•
REMARKS:
Scott,
I left you a voicemail and sent you an email earlier this morning regarding the Riverside Village
and Fire Station Area submittal for River Dunes. We would like to request an extension for
submitting the responses to your comments from last week. I don't know if we should just give
you a date, or if you need to look at the calendar and propose a couple dates.
One of the main reasons for this extension request is to be able to discuss with you a little bit
more the flow distribution device for the basin(s).
Please call me to discuss when you get a chance, Thanks for your assistance,

v�MCKIM&CREED
September 22, 2008
ENGINEERS
SURVEYORS
PLANNERS
04135-0001 (40)
Mr. Scott Vinson
Division of Water Quality
North Carolina Department of Environmental and Natural Resources
943 Washington Square Mall
Washington, NC 27889
RE: River Dunes Marina and Residential Development, Pamlico County,
North Carolina
High Density Stormwater Permit
Dear Mr. Vinson:
On behalf of River Dunes Corporation and Ed Mitchell, please find enclosed for
your review the high density stormwater permit for the River Dunes Marina and
Residential Development located in Pamlico County, North Carolina. This
permit specifically covers Riverside Village and Fire Station Area.
0.�EA5 PEDp
cr River Dunes Corporation will be delivering separately the following item:
Wm s 1) Check for $4,000 for express review permit application fee
Lo
Ix
z>- I If you have any questions or request additional information, please let me know.
7 D
T
wO j arms ��i Sincerely,
McKIM & CREED, P.A.
Venture IV Bvildi ng �n A �—f
1730 Varsity Drive
Raleigh, NC 27606 Curt Blazier, PE
Project Manager
919. 233. 8091
Fox 919.233,8031
w w w.mckimcreed.com

For DENR Use ONLY
North Carolina Department of Environment and Reviewer `ddL�-rr
A&0i- Natural Resources Submit
NCDENR Request for Express Permit Review Time:
Confirm:
FILL-IN all the information below and CHECK the Permit(s) you are requesting for express review. FAX or Email the completed form to Express
Coordinator along with a completed DETAILED narrative, site plan (PDF file) and vicinity map (same items expected in the application package
of the project location. Please Include this form in the application package.
• Asheville Region -Alison Davidson 828.296-4698;alison.davidsonca)ncmail.net
• Fayetteville or Raleigh Region -David Lee 919-791.4203; david.lee(a)ncmail.net
• Mooresville & -Patrick Grogan 704-663-3772 or patrick.grogan0mcmail.net
• Washington Region -Lyn Hardison 252.946.9215 or lvn.hardisont7gAncmail.net
• Wilmington Region -Janet Russell 910.350-2004orjanet.russell(7pncmail.net PRESS
NOTE: Project application received after 12 noon will be stamped in the following work day. S E P 2 3 2008
Project Name: RIVER DUNES MARINA & RESIDENTIAL RIVERSIDE & EM. County: PAMLICO NC ®���
Applicant: ED MITCHELL Company: RIVER DUNES CORPORATION
Address: 416-A POLLOCK STREETCity: NEW BERN, State: NC Zip: 28560- .
Phone: [phone] Fax::[phone] Email: [e-mail]
Physical Location:SR 1317
Project Drains into _ waters — Water classification _ (for classification see-http://h2o.enr.state.nc.us/bims/reports/reportsWB.htmi
Project Located in NEUSE River Basin. Is project draining to class ORW waters? Y/N ,within 1,4 mile and draining to class SA waters Y. or
within 1 mile and draining to class HOW waters? Y/N
Engineer/Consultant: CURTIS BLAZIER Company: MCKIM & CREED
Address: 1730 VARSITY DRIVE, SUITE 500 City: RALEIGH, State: NC Zip: 27606-_
Phone: [phone] Fax::[phone] Email: [e-mail]
(Check all that apply)
❑ Scoping Meeting ONLY ❑ DWQ, ❑ DCM, ❑ DLR, ❑ OTHER: _
❑ Stream Origin Determination: # of stream calls — Please attach TOPO map marking the areas in questions
® State Stormwater ❑ General ❑ SFR, ❑Bkhd & Bt Rmp, ❑ Clear & Grub, ❑ Utility
❑ Low Density ❑ Low Density -Curb & Gutter _ # Curb Outlet Swales ❑ Off -site [SW _ (Provide permit #)]
❑ High Density -Detention Pond _ # Treatment Systems ® High Density -Infiltration 4 #Treatment Systems
❑ High Density -Bio-Retention _ # Treatment Systems ❑ High Density—Stormwater Wetlands _ # Treatment Systems
ElHigh Density -Other _ # Treatment Systems /❑ MODIFICATION: [IMajor ❑ Minor [IRevision SW
❑ Coastal Management ❑ Excavation & Fill ❑ Bridges & Culverts ❑ Structures Information
❑ Upland Development ❑ Marina Development ❑ Urban Waterfront
❑ Land Quality ❑ Erosion and Sedimentation Control Plan with _ acres to be disturbed.(CK # (for DENR use))
WETLANDS QUESTIONS MUST BEADDRESSED BELOW
H Wetlands (401): Check all that apply
Wetlands on Site ❑ Yes ❑ No
Wetlands Delineation has been completed: ❑ Yes ❑ No
US ACOE Approval of Delineation completed: ❑ Yes ❑ No
404 Application in Process w/ US ACOE: ❑ Yes ❑ No
Permit Received from US ACOE ❑ Yes ❑ No
Isolated wetland on Property ❑ Yes ❑ NO
Buffer Impacts: ❑ No ❑ YES: _acre(s)
Minor Variance: ❑ No ❑ YES
Major General Variance ❑ No ❑ YES
401 Application required: ❑Yes ❑ No If YES, ❑ Regular
Perennial, Blue line stream, etc on site ❑ yes ❑ No
For DENR use only
Fee Split for mulftle oermits: (Check# 31 o%1 TotalFeaAmount S
SUBMITTAL DATES
I Fee
SUBMITTAL DATES
Fee
CAMA
$
Variance Maj; LJ Min)
$
SW ® HD, ❑ LD, ❑ Gen
$ tpo p p
401:
1
$
LQS
$
Stream Deter,_
$
NCDENR EXPRESS July 2008

• STORMWATER MANAGEMENT PERMIT APPLICATION FOR (SWU-101
VER 03.27.08)
PART III. PROJECT INFORMATION
ITEM 1 DETAIL NARRATIVE — Addendum 1
RIVER DUNES MARINA AND RESIDENTIAL DEVELOPMENT,
for
RIVER DUNES CORPORATION
OCT 2 8 2008
HIGH DENSITY STORMWATER MANAGEMENT PLAN r .:
RIVERSIDE VILLAGE AND FIRE STATION AREA
The project site is located in Pamlico County at the confluence of Broad Creek and the
Neuse River. The 1327-acre tract, owned by River Dunes Corporation, consists
predominantly of loblolly pine stands characteristic of timber production use. Common
soil units of upland areas include Wahee fine sandy loam, Argent loam, Yonges loamy
fine sand, Fork loamy fine sand, and Altavista loamy fine sand.
The existing drainage patterns at the site form seven drainage areas which discharge to
the Tar, Broad, Paris, Mill, Cedar and Gum Thickets Creeks and the Neuse River. A
conservation easement has been placed on the area of the Gum Thicket Creek watershed.
• The proposed subdivision is designed to preserve these seven existing drainage patterns
within the project area.
The River Dunes Marina and Residential Development has been planned as an overall
low -density development in compliance with the coastal stormwater regulations. The
low density stormwater management permit SW7060204 has been approved by
NCDENR. There are several parcels, collectively described as the Harbor Village
Residential Areas, the Harbor Village Center and Riverside Village (see Sheet M-1),
which fall under the overall low -density provisions with respect to gross acreage but will
be developed at higher net densities than the remainder of the property. The developer
will employ a best management practice approach to these parcels to insure that water
quality objectives are met for the entire property. A series of shallow grassed infiltration
basins will be employed at scattered strategic locations as needed to capture and infiltrate
stormwater runoff from roadways and home sites. The use of stormwater culverts will be
limited. Home sites and roadways will be setback from wooded wetlands where feasible
to allow for a riparian buffer to dissipate sheet runoff. Other collected stormwater runoff
will be directed to adjacent upland wooded areas and discharged into these areas through
level spreader type devices in order to further assure maintenance of water quality. The
eleven areas included in this approach will be the Harbor Villages I to VI, Riverside
Village, Section 4A, the Village Center and Marina Service Area, the RV & Boat Storage
Area and the Future Commercial along Orchard Creek Rd. (see Sheet M-1).
0

® The high density pocket of development covered in this permit application includes
Riverside Village and the Fire Station Area, containing approximately 691,345 square
feet, or 15.9 acres. Riverside Village consists of 40 high density lots and three drainage
areas which discharge to Gum Thicket Creek, which outlets into the Neuse River. Three
infiltration basins are proposed for stormwater management purposes (see Sheet M-1 for
master plan of development). Maximum built upon areas per lot on shown on Exhibit A.
The Fire Station Area consists of one drainage area which discharges to Tar Creek, which
flows into Broad Creek, which discharges to the Neuse River. One infiltration basin is
proposed for stormwater management purposes (see Sheet M-1 for master plan of
development). Maximum built upon acreage for the area is 0.72 acres. The project area
consists of a fire station, an EMS building, emergency service personnel office space, a
commercial building, drive aisles and parking areas.
The following comments address stormwater solutions for this specific area of the River
Dunes development plan:
Three infiltration basins (RS-1, RS-2, and RS-3) will be constructed to control stormwater
runoff and discharge it to the Neuse River via wetlands fingers to the north of the site area
(see Sheet C1.1). Level spreader overflow devices (LS-1, LS-2, and LS-3) located on the
berms surrounding the basins and grassed filter strips will be utilized to minimize impact to
adjacent wetlands and ensure state water quality standards. Stormwater runoff from the
three drainage areas will be collected in the roadways and enter the basins through
® subsurface pipes from grated inlets, as well as through sheet flow and grassed swales. Both
corrugated HDPE and RCP will be used to collect and transport stormwater runoff. Sumps
in the bottom of the curb and grated inlets, inflow pipes and rip -rap energy dissipaters will
act as pretreatment for the infiltration basins. An open half -pipe structure will be placed
along the bottom of each basin starting at the outlet structure to distribute flow throughout
the basin (see Sheets C3.1, D6, D7).
One infiltration basin FS-1 will be constructed in the northwestern portion of the fire
station area to control stormwater runoff and discharge it to the Neuse River via wetlands
to the west (see Sheets C1.1 and C3.1). A level spreader overflow device located on the
berm surrounding the basin, a grassed swale and vegetated filter strips will be utilized to
minimize impact to adjacent wetlands and ensure state water quality standards. Stormwater
runoff from the drainage area will enter the basin via sheet flow and grassed swales. These
swales in addition to the grassed filter strips will act as pretreatment for the stormwater
runoff.
The BMP areas will have their soils re-evaluated prior to construction. A silty clay layer
approximately two to three feet in thickness exists at both basin locations (see geotechnical
report and borings). This clay layer will be removed and replaced with suitable sandy fill
per NCDENR Stormwater BMP Manual standards (see Exhibits B and Q. Double -ring
infiltrometer tests were run on the infiltrating soils in each basin. These results are shown
in the tables in the back of the geotechnical data section. The average infiltration rates for
® basins RS-I, RS-2, and RS-3 were all slightly below the minimum 0.52 inches per hour
required by NCDENR. In addition to replacing unsuitable soils in the basin areas, suitable

• fill will also be placed in areas immediately around the four infiltration basins, especially in
the area between the basin and the wetlands. The extent of the fill placement will be
governed by the location of the adjacent roadways. The placement of the suitable fill will
help the stormwater to flow vertically and horizontally and prevent the formation of a clay
barrier wall around the basins.
The River Dunes property will be developed in a way that should meet the Neuse River
Basinwide goal of protecting waters while accommodating economic growth.
Additional BMPs will be employed to minimize impact to sensitive groundwater
recharge areas. Measures may include conveying stormwater from roof -tops and
walkways into dry gravel wells, applying gravel under decks to stabilize non -vegetated
surfaces, locating sheds and garage structures upland from the shoreline, and surfacing
parking pads with turf block or Geo mat. Grading will direct runoff toward woody
wetlands for additional filtration prior to groundwater recharge.
The marina Basin excavation will provide in excess of 500,000 cubic yards of material
for use on site as fill for road construction throughout the project and for site
development of the marina service areas (i.e. clubhouses, post office, retail, fitness and
spa, chapel, swimming pools, and village center). This fill will also be utilized to prepare
sites for developer construction clustered residential units. The excavated material
consists of sand, sandy clay and sandy loam that is generally considered suitable for both
compacted engineered fill for roadways, parking area and building pads and for on -
compacted fill for landscape and infiltration areas. The infiltration areas proposed will be
constructed on the fill area in order to obtain sufficient separation from groundwater as
well as providing head to the discharge from the basins to drive the water into the
existing vegetated riparian buffer areas without concentrating the flow.
The design of infiltration basins will be in general accordance with NCDENR guidelines
and will include suitable volume to contain runoff from a three (3) inch storm. An
overflow "spillway" will be installed to allow excess water to be quickly removed from
the infiltration basins during periods of rainfall in excess of the design storm. Vegetation
within the infiltration basins will be as recommended by the NCSU Extension Service.
Again, it is the intent of River Dunes Corporation to develop River Dunes in a way that
should meet the Neuse River Basin wide goal of protecting waters while accommodating
economic growth. For further information on the overall stormwater management plan
for the development, please refer to permit SW7060204 and associated application.
0

1.4
Carolina Engineers, P.A.
Sieve Analysis Report
SOURCE OF MATERIAL; North Side Marina Stockpile CLIENT: River Dunes Corporation
PROJECT: River Dunes; Pamlico County, NC PROP. USE: �lnfiltraton.Basin-Fil6Matedal�
SAMPLED: May 24, 2006 PROJECT NO. 4B4
SAMPLE NUMBER: No. 1
SIEVE ANALYSIS
DATE: 5125/2006
TECHNICIAN: John Switzer
SAMPLE SIZE. 741.5 (g)
Sieve Size
Weight
Retained
Percent
Retained
Total Percent
Passed
Specifications
#4
1.2
0.16
99.13
NA
#10
2.1
0.26
99.7
NA
#40
374.4
50.5
49.5
NA
#200
691.5
93.4
1 6.6
1 NA

. �xkrar7- C
Laboratory Report Version 4.2
Permeability of Granular Soils (Constant Head)
ASTM D 2434
ect #: 1053-07- Report Date: 3/27/07
! :et Name: Trader Construction Company Test Date(s) 3/23 - 3/26/07
Client Name: Trader Construction Company
Client Address: .2500 Hwy. 70 East, New Bern, NC 28560
During rvo. ouuc nag Sample No. 2 Sample Date: 3/5/07
Location: Basin 2A - Stockpile at Riverside Elevation: NA
oampie Lescnpnon: Light Brown SAND (Visual)
{?„ �°rnti'vcime �Pazamers �
-
Diameter, in.
2.879
Diameter, in:
N 2.879
Length, in:
5.740
Length, in:
5.740
Wet Unit Weight, pcf:
121.4
Wet Unit Weight, pci
128.6
Dry Unit Weight, pcf:
103.7
Dry Unit Weight, pcf:
103.7
Moisture Content, %:
17.0
Moisture Content, %:
24.0
i.
��ir�r'``,�i�r��_r�'�'PERhREA811=1NMEASUREhSENTS3:�i,
Q �
ry"�''��`,��
sx rt in lemma ° nc
uncorrected correctedx�
1
53.17
9.00
19.0
8.97E-04
9.20E--04
2
51.87
9.00
19.0
.8.75E-04
8.97E-04
3
154.82
28.00
19.0
8.40E-04
8.6IE-04
} %;!'L',Kavera'gef5
r
8.71E-09
8.92E-04
L, cm: 14.580
A, cm 2: 41.999
h; cm: '38.100
k=VL/60A th
where:
k = hydraulic conductivity, cm,1sec
V = volume of water discharged, cm 3
L = length of test specimen, cm
A = cross -sectional area of test specimen, cm `
t = total time of discharge, min
h = hydraulic head difference (HI - H2), cm
SOIL
SPECIMEN
Remarks: Test specimen compacted to 100% at 2.0% wet of optimum moisture (ASTM D-698).
References: ASTM D422: Method for Particle -Size Analisys of Soils
' OcianName:
'I—nnical Responsibility:
Mal Kraian
Mal Kraian
sr".,,..
CONSTANT
HEAD
FILTER
HI
Laboratory Supervisor
Pun'/.
S&A'IE, INC.
3201 Spring Forest Road
Raleigh, NC 27616
Sample 92 Basin 2A - Stocpile at Riverside

FIDE STATION AREA
CALCULATIONS
ADDITIONAL INFORMATION
OCTOBER 27, 2008
ocj 2 s ZooB
owe
'PROS #
0

• INFILTRATION BASIN DESIGN Page 1 of
River Dunes Fire Station Area
Infiltration Basin FS-1
•
Project: 04135-0002
Prepared by: GCA
Date: 9/1912008
Drainage area: 63,784 sf
Volume to Catch The First 3.0 Inches of Runoff: (no bypass provided)
Runoff: Rv = 0.05 + 0.009' I Simple Method, Schueler
Rv = 0.5527577
Volume:
V = P' Rv' A
V =
8,814 cf
Surface Area:
SA = Volume / Depth
Depth =
12 in
SA =
8,814 sf
Select Fill Soil
Soil
Conductivity (k)
(in / hr)
Sand
6
Loamy Sand
2
Sandy Loam
0.5 - 1
Clay Soils: Use Sandy Loam or Loam PL
Fill Soil = Loamy Sand
k= 1.3
I = Impervious Percent =
Rv = Runoff Coefficient
V = Required Storage Volume
P = Design Rainfall =
A = Drainage Area
56
3 inch
Cover
SF
Acres
Sdewalks: ns sf .;
?i1 925
0 0,4'
Streets ; �;t 1 "
0"7
t' xJY
1
B it ings_''� , '
00650
r�a024�
T23 056 {
0 00 r-.
Landscape
32,779
0.75
Other
0
0.00
Totals
63,784 1.46
Elev
Area
I Incr Vol
Cumulative
Volume
vs.
Required Volume
Results
3.20
9092.00
0.00
0.00
8,814
122 22ll
4.00
10114.00
7698.40
7698.40
>
8,814
Too Small
4.20
10424..0
2057.801
9756.20
>
1 8,814
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• INFILTRATION BASIN DESIGN Page
River Dunes Fire Station Area
Infiltration Basin FS-1
Predevelopment Runoff Volume:
Volume = Depth x Rv x Drainage Area
Depth = 3.48 inches
Drainage Area = 63,784
Rv = 0.05 + 0.009 . I I = Impervious percent= 0
Rv = 0.05
Volume = 925 cf
Postdevelopment Runoff Volume:
Volume = Depth x Rv x Drainage Area
Depth = 3.48
Drainage Area = 63,784
• Rv = 0.05 + 0.009 ' I I = Impervious Percent = 56
Rv = 0.55
Volume= 10,225 cf
0
2.5
3.5
4.5
A Runoff Volume:
10225 cf - 925 cf = 9300 cf
Detention is required
Detention provided = 9756 cf
9756 > 9300

u
• INFILTRATION BASIN DESIGN Page 3 of 3
River Dunes Fire Station Area
Infiltration Basin FS-1
Find Time Drawdown of Water Through Soil Laver:
A. Rate of Drawdown: Qd = (2.3e-5) * k * SA * H / L H / L Approximatley = 1
Qd= 0.2719 cf
B. Find Time to Drawdown Water from Inundation to Saturation at Surface:
Volume to Drawdown: Vi-s = SA * Depth
Vi-s = 9,756
Time to Remove Volume of Water at Flowrate Qd:
Ti-s = Vi-s / Qd = 35,888 sec.
= 10 hr.
C. Find Time to Drawdown Water from Saturation at Surface to 2 feet Below Surface:
• Porosity (n) = 0.38
Volume to Drawdown: Vi-s = 2 feet * SA * n
Vs-2 = 7,922
Time to Remove Volume of Water at Flowrate Qd:
Ts-2 = Vs-2 / Qd = 29,142 sec.
= 8 hrs
D. Total Time to Draw Water Through Soil:
T= 18 hrs
•