365 8TH ST - REVISION PU DRAINAGE CITY OF ATLANTIC BEACH
800 Seminole Road
`k„lvr ry Atlantic Beach, Florida 32233
( )
904
Telephone 247-5800
�r P
X FAX(904)247-5845
Ji JBL
REVISION REQUEST SHEET
Date: I6' - Received by: Resubmitted:
Permit N lmbe : I q-/<ll;t 'T
Original Plans Examiner, ,,nT,. JAI„ , <M a Project Name: I=g spa
e2 Ca Project Address $TN $-L _
Contractor: M4AmerNy guuC1&_GS Contact Name:
Contact Phone : 9o4 - g13 - 17776 Contact e-mail: ac/.. &
Revision/Plan Check/Permit Fee(s) Due: $
Description of Proposed Revision to Existing Permit:
CM.,11a F4nM F{F-a.JT,C W PDNn Tp 6U[3CIi2 FLCE
Ir.I F,LTR wTa nw $x$S'�
Additional Increase in Building Value: $ - 0— Additional S.F. - co
Site Plan Revised: _ It/25 /t Public W/U Approval:_
By signing below. l (ppm name) JO GFPN �] Tar-:A affirm that the above revision
is inclusive of the proposed changes.
Signature of C01 ractm'/Agent(Contraaor mus[six�,ifinerense ni v:Aualion) Dz �pr_��y/�_(y�
oniceuseonly — " LSA
� D
Approved: Rejected: No � V2— _"�_
Plan Review Comments:
Department review required _Yes No ' / �-
Building ry,
Planning &Zoning -- --
Tree Administrator Plans Examiner
Public Works
Public Utilities
Public Safety
Fire Services Date
252 Otterwood Ct
Jacksonville, FL 32225
Mr Doug Layton
Mr Scott Williams
Department of Public Works
City of Atlantic Beach
1200 Sandpiper Lane
Atlantic Beach, FL 32233
Re: Stormwater Management System
365 8th Street,Atlantic Beach
Dear Doug and Scott:
Enclosed is our Revision Request Sheet to permit installation of a subsurface Stormwater
Management System at the above referenced residential lot. The original plan was for a
retention pond but the owner has opted for the system described herein for reasons of public
health and enjoyment of their limited backyard.
The Plan reflects the several discussions we have had over the past few weeks. It is
considerably simpler than any of the conceptual plans I showed you as well as distributing
stormwater falling on the site more broadly around the site. I am confident that it will handle
almost any foreseeable precipitation event.
Thanks for the patience you've shown in helping me get up to speed on this issue. Please
contact me should you have any questions or comments on the enclosed.
Very truly yours,
J.../ti <Ll,
Joseph W Sheahan
Consulting Hydrogeologist
End
Cc: Adam Smythers (w/encl)
Ed Hebert (w/encl)
3658th LTR 112415a Aoa
11/24/15 22:27
SPECIFICATIONS
STORMWATER MANAGEMENT SYSTEM
365 8tfi Street
Atlantic Beach, FL
November 24,2015
BACKGROUND
The City of Atlantic Beach requires that stormwater falling on sites of new construction must be
managed on site, i.e., ideally no stormwater from the site will discharge to the city's storm
sewers.
The architect of the house under construction at the site has calculated that the rain event
specified by the city could produce 2,155 cubic feet (ft') or 16,371 gallons of stormwater; this
becomes the storage volume required by the city. The conventional approach - stormwater
retention basins - entails several drawbacks including serving as mosquito breeding grounds,
undesirable from a public health perspective.
SYSTEM CAPACITY
The design objective was to find 2,155 ft3 of stormwater storage space in some combination of
subsurface piping volume plus the pore space in the lower 3.5 feet of unsaturated soils
underlying the site. The approach taken is to use slotted corrugated pipe to distribute the
stormwater to the unsaturated soils. The site was divided into four areas for the analysis. The
attached spreadsheet presents the calculations of storage volumes for different pipe sizes in
each area. The cells stippled and shaded blue contain the options selected to attain the
required volume with 4% excess capacity. The Proposed Layout, Stormwater Management
System shows the system configuration based on the spreadsheet and input from the drainage
contractor.
The calculations probably merit some explanation. I divided the site into four areas, North, East,
South and West. The North Area is the backyard where the Retention Pond was to go. The East
Side is a narrow strip between the new house and the adjacent lot. The South Area is now a
courtyard and the front yard of the property; tiles were installed in this areas before the
courtyard walls were poured to handle downspout flow. Finally,the West Area is the driveway
serving a side-load garage on the ground level; the driveway is being finished with pervious
pavers.
365 specifications 112415b.Docx 1
11/24/15 21:52
The city recognizes the capacity of the pore space in the unsaturated soils (i.e., above the water
table) to hold stormwater. In calculating the site-specific available pore volume, the city
assumes a soil porosity of 30% and a water table elevation of 3.0 feet. These parameters are
incorporated in the spreadsheet.
The first column shows the minimum length of slotted pipe to be installed in a given area..The
south and east sides have two relatively closely spaced slotted pipes each. The second column
shows that, due to the pipes' proximity, each side is assumed to have an infiltration area only
two feet wide, or one foot per tile. As we discussed, each pipe actually discharges to a
considerably wider area. The second column shows that the three tiles spaced on four-foot
centers in the wider North and West Areas,discharge to an area 12 feet wide, consistent with
the plan with which you had at one time concurred for the North Side. Both of these areas
have considerably greater areas and volumes to handle any infiltrating water.
In all cases, I have assumed a conservative 3.5 feet of unsaturated soils beneath the pipes to
absorb the infiltrating waters. These values are combined with the City's default value of 30%
porosity to yield the total unsaturated pore volumes calculated in the Column titled 30%
Volume,ft3. As shown at the bottom of that column, the unsaturated soils can hold 2,098 ft3 of
the 2,155 ft3 required
The next section of the spreadsheet calculates the volumes of the lengths of pipe specified in
Column 1 for various pipe diameters to permit optimization of the system design. Six-inch
corrugated, slotted HDPE pipe was chosen for all four areas, yielding an additional 138 ft3 of
storage volume. The total volume in the system so designed is 2,336 ft3, or 4% more than
required.
SYSTEM DESIGN
The infiltration system is designed to serve a purpose completely opposite from most piping
systems. Typical gravity piping systems are designed to convey liquids from Point A to Point B,
as efficiently as possible with no loss of the contents of the system. An infiltration system,
conversely, is designed to allow all of its contents to leak out and prevent discharges from the
end of the system.
The infiltration system will be installed with all pipe inverts on the north, south and east sides
set at an elevation of 6.5 ft., or 3.5 feet above the assumed water table, i.e., 1.0 foot below the
final site grade of 7.5 ft. (NAVD88). The tiles under the drive on the west side of the property
will be set at an invert elevation of 6.3 ft to accommodate the overlying pervious pavers. Cross
365 S,dficatw,112415b. o. 2
11/24/15 21:52
section A - A' shows the placement of the tiles under the drive relative to the fill placed to bed
the pavers.
The infiltration gallery will end at an overflow outlet box which is designed to prevent water
from seeping to the surface should the infiltration gallery ever become overloaded. The invert
of the discharge from the overflow structure will be set at an elevation of 7.0 ft, i.e., at the top
of the inside of the 6" corrugated pipe in the infiltration gallery at its far extent. The overflow
structure will gravity drain to an overflow discharge adjacent to the driveway and behind the
sidewalk.
Prepared by:
Joseph W. Sheahan
Consulting Hydrogeologist
365 specifications 112415b.Dov 3
11/20/15 2352
d $ a ;
E 'c
° oo � n3
. � _ � m s
Y
- a e r
a m ° m s
,� o E C
3-- - ° o iN. mi
o r
y�
2
G r ,
Z ? ' �
N
WLL m ry m ry O
iN N m n w u �
N
~ m � \_ N
Z '_ `o a
� "- 3 e
� A w m ry
a �
i ry d c E
a n ¢ � v
m � � � a
m e w m, � �
� .. P c r. n � q _. o
N � ] � Z
C' L
r
w r J ^
F � � O r
m h � & d N a
� �
¢ o or
O :_ �
N � � m m m m
J
� QUQiV
2 Q ? I
� O v � r
V � 6
O ¢
O ry r
F
p Y
p LL Q
�+ t 6
w �' i'n
c z n
o "JY ,+„
Q �: OE
�'. m.
6 �w �2 ++yam
O � YIY '� �' G:
� a � h O �
i < u
� ° 3 0 0��0 o z a. o \.
°
v o °
a � 'E
O L W
Oj 'o N
I
V Z �
N
>- J 3x r m
0' ------ N 6L r°t m° c 000
Z
LLJ
m vLU
o Z
/U z
V U O a a a M V
a ur a e V
C O N C O
m N
oda __ m
Ln 20
uj
J I'- CJ nr c r i
00Ln cu
v a
O a v
x � Z d (n M Z CL CL o
d h
` 0to
a —
O ..
lV
4 F
u
'Jl M O
LU
IA
W m
V ai
M
F j Q Y , b\ CQC m
G Q C
N —
'J1 7 Z �
} Ol .0
Z1 i C
O W 41p Q al
�C L N
F (J Q
(A �C/ M Q
A� 1 kn LV 00 E
C o
fn D V
Ln (D z a .0
� I x
n
U.
o u uV7zt g
ni
0
� V h Li
c
3
P