HomeMy WebLinkAboutCT 16-02; OCEAN; PRELIMINARY DRAINAGE REPORT FOR OCEAN CONDOMINIUMS; 2016-08-23• • • • • • •
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PRELIMINARY DRAINAGE REPORT
FOR
OCEAN CONDOMINIUMS
August23,2016
Prepared for:
MJNF Holding, LLC
1907 Apple St, Suite 8
Oceanside, CA 92054
Prepared by:
David Wiener, P.E.
5050 Avenida Encinas, Suite 260
Carlsbad , CA 92008
(760) 603-6252
dwiener@mbakerintl.com
Michael Baker
INTERNATIONAL
RECEIVED
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Table of Contents
1 Introduction and Purpose ....................................................................................... 1
1.1 Background and Project Description .............................................................. 1
1.2 Pre-Development Drainage Patterns .............................................................. 1
1.3 Post Development Drainage Patterns ............................................................. 1
2 Rational Hydrology ................................................................................................. 2
3
4
Detention Calculations ............................................................................................ 2
Conclusions ............................................................................................................ 3
Technical Appendices
Appendix A: Existing Hydrology Map
Appendix B: Proposed Hydrology Map
Appendix C: Detention Calculations
Ocean Condominiums
Preliminary Drainage Report Michael Baker
INTERNATIONAL
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1 Introduction and Purpose
1.1 Background and Project Description
The site is located at 2501 State Street in Carlsbad, California. APN 155-200-04. The
parcel area is 0.49 acres. In the existing condition, the project site is occupied by an
office building (Soil Retention Systems Inc.) with asphalt parking lot. The site is
surrounded by NCTD right-of-way to the west, State Street to the east, senior living to
the north, and recently constructed condominiums to the south.
In the proposed condition, the existing building and parking will be demolished and
removed. In its place, 17 condominium units will be constructed on a podium deck. The
podium will enclose the proposed parking structure. The finish floor of the parking
structure will be approximately 3 feet below existing grade. A new driveway entrance off
of State Street will be constructed for the parking structure.
1.2 Pre-Development Drainage Patterns
The runoff from the site flows to the east to State Street via surface flow, roof
downspouts and a sidewalk underdrain. Area drains capture the flow on site and convey
it to sidewalk underdrain. Once in the curb and gutter of State Street, flow travels to the
north, where it enters existing storm drain piping. The piping outfalls to Buena Vista
Lagoon via 66" pipe. A small portion of the site (approximately 0.4 acres, or 8% of the
parcel area) flows to the adjacent properties to the north and west. Refer to the Existing
Hydrology Map in Appendix A.
1.3 Post-Development Drainage Patterns
Drainage patterns will not change as a result of the project. However there will no longer
be flows to adjacent properties. The entire site will be captured in private onsite drainage
piping and discharge to State Street via sidewalk underdrains. The majority of the site
will consist of the building structure (approximately 0.42 acres). Rainfall that hits the
exposed surface (roof and hardscape) of the building will be directed to raised planters.
The planters will connect to drain piping through the building and onto State Street.
Approximately 0.07 acres of the site beyond the building structure will consist of
permeable paver walkways, landscape area, and concrete hardscape. These areas will
sheet flow or area drain to State Street. Refer to the Proposed Hydraulics Exhibit in
Appendix B.
Ocean Condominiums
Preliminary Drainage Report 1 Michael Baker
INTERNATIONAL
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2 Rational Hydrology
The Rational Method hydrology study was completed using methodology described in
the San Diego County Hydrology Manual. The design storm for this study is the 100-year
events. Using the San Diego County Hydrology Manual lsopluvial Map, the 100-year PG
was found to be 2.5 inches. Based on the geotechnical report for the project, the soil
type was assumed to be type 'D'. A runoff coefficient ("C") value of 0.35 was used for
pervious area and 0.90 for impervious areas. In the existing condition, C was assumed
to be 0.85 per the Manual for office/commercial site. The time of concentration (Tc) to
each node was assumed to be 5 minutes.
The intensity was found using Figure 3-2 (San Diego County Hydrology Manual). The
drainage areas and node designations used can be seen on the Hydrology Maps in
Appendices A and B. The flow (Q) at each node was calculated using the Rational
Equation Q=CIA, where:
• Q = Flow (cubic feet per second)
• C = runoff coefficient
• I = Intensity (inches per hour)
• A= Drainage Area (acres)
3 Detention Calculations
Rational method calculations determined that peak flowrate in the proposed condition is
2.68 cfs. Therefore detention measures must be used to attenuate the flow to the pre-
development level of 2.52 cfs. Flow reduction of at least 0.16 cfs is required. Using
results from rational method calculations for peak flow in the proposed condition, 6-hour
hydrographs were generated using the County approved software prepared by Rick
Engineering Company, which utilizes the methods described in Section 6 of the San
Diego County Hydrology Manual. Hydraflow Hydrographs software was used to route
the post-development hydrographs through proposed biofiltration planters, which will
provide both flood control and water quality treatment. The biofiltration planters were
modeled using stage, storage, discharge data produced by San Diego Hydrology Model
(SOHM). The detention and peak flow mitigation calculations can be found in Appendix
C. The biofiltration planter details can be found on the DMA Plan, and in the Storm
Water Quality Management Plan (SWQMP) for the project.
Ocean Condominiums
Preliminary Drainage Report 2 Michael Baker
INTERNATIONAL
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4 Conclusions
Drainage patterns will not change significantly as a result of the proposed improvements.
In both the existing and proposed condition the site drains to State Street via sidewalk
underdrain pipe. The project will decrease peak 100-year discharges from the project
site. Peak flow is mitigated by routing through the proposed biofiltration raised planters
on the podium deck. The peak flows in the existing versus proposed condition on shown
below. Refer to the attached Appendices for maps and calculations.
Proposed piping from the site will consist of sidewalk underdrains. From Manning's
Equation, Omax in a 4" underdrain pipe at 2% slope is 0.36 cfs. Based on the peak flow
of 0.91 cfs in the proposed condition, there will need to be three 4" sidewalk underdrain
connections from the site, outfalling to the gutter on State Street.
Existino Condition
A (acres) I C I Q100 (cfs)
0.45 I 0.85 I 2.52
Proposed Condition
Area A (acres)
A
B
Total
Ocean Condominiums
Preliminary Drainage Report
0.42
0.07
0.49
C 0100 (cfs)
0.85 2.49
0.39 0.19
2.68
3
Mitigated
Q100 (cfs}
0.72
0.19
0.91
Michael Baker
INTERNATIONAL
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Appendix A: Existing Hydrology Map
I
20 10 0 20 40 50
~I ~1 .:J1----r i----;1
SCALE: 1 "=20 '
HYDROLOGY CALCULATIONS
DRAINAGE AREA= 19,500 SF= 0.45 ACRES
C = 0.85 (TABLE 3-1: OFFICE)
Tc= 5 MINUTES (ASSUMED MIN.)
PB (100) = 2.5 INCHES
I100 = 7.44 P6 (TcA-.645) = 6.6 INCHES/HOUR
0100 =CIA= 0.85 * 6.6 * 0.45 = 2.52 CFS
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/ I EX.
LEGEND
EX . CONTOUR -( I J )--
EXISTING STORM DRAIN ---Su----
PROJECT DRAINAGE BOUNDARY-----
DIRECTION OF FLOW
SITE DISCHARGE POINT -
Ocean CONDOMINIUMS
EXISTING HYDROLOGY MAP
Michael Baker
INTERNATIONAL
5050 Avenida Encinas
Suite 260
Carlsbad, CA 92008
Phone: (760) 476-9193
MBAKERINTL.COM
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Appendix B: Proposed Hydrology Map
.,,. .,,.
PROP.
POINT.
•..
s iTE DISCHARGE····
0100 = 0.91 cfs
3 CURB OUTLE_TS
/
/
PLANVIEW -ABOVE PODIUM DECK
Existing Condition
A (acres) C
0.45 0 .. 85
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Q100 (cfs)
'} 5')
.~11/H; ....
LEGEND
RAISED PLANTER ON PODIUM DECK
(BIOFILTRATION BMP)
IMPERVIOUS ROOF f;:'·,·· .',1
IMPERVIOUS EXPOSED HARDSCAPE I : • : I
DRAINAGE AREA ~
HYDROLOGY CALCULATIONS -AREA A
DRAINAGE AREA= 18,290 SF= 0.42 ACRES
C = 0.90 (PODIUM)
Tc= 5 MINUTES (ASSUMED MIN.)
Ps (100) = 2.5 INCHES
!100 = 7.44 Ps (TcA-.645) = 6.6 INCHES/HOUR
Q100 = CIA = 0.90 * 6.6 * 0.345 = 2.49 CFS UNMITIGATED
0100 = 0 . 72 CFS MIT I GA TED ( THROUGH PLANTERS)
20 10 0 20 40 60 1-~f---1 ___ 1----i1
SCALE: 1 "=20'
.~···
PROP . SI TE DI SCHARGE·· · -
POINT. 0100 = 0.91 cfs
3 CURB OUTLETS
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RAISED
PODIUM
-----··
/
GROUND LEVEL -OUTSIDE OF PODIUM
Proposed Condition
Area A (acres) C 0100 (cfs) Mitigated
0100 (cfs)
A 0.42 0.85 2.49 0.72
B 0.07 0.39 0.19 0.19
Total 0.49 2.68 0.91
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LEGEND
PERMEABLE PA VER WALKWAY fbsj:Lc't:j~
LANDSCAPE AREA
DRAINAGE AREA
HYDROLOGY CALCULATIONS -AREA B
DRAINAGE AREA= 3,245 SF= 0.074 ACRES
IMPERVIOUS AREA= 225 SF= 7%
C = 0.9(7%) + 0.35(93%) = 0.39
Tc= 5 MINUTES (ASSUMED MIN.)
Ps (100) = 2.5 INCHES
!100 = 7.44 Ps (TcA-.645) = 6.6 INCHES/HOUR
0100 =CIA= 0.39 * 6.6 * 0.074 = 0. 19 CFS
Ocean CONDOMINIUMS
PROPOSED HYDROLOGY MAP
Michael Baker
INTERNATIONAL
5050 Avenida Encinas
Suite 260
Carlsbad, CA 92008
Phone: (760) 476-9193
MBAKERINTL.COM
E ~ 0
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-·-..... ' ~ _-~,
'-.::----~· ------
Appendix C: Proposed Detention Calculations
RATIONAL METHOD HYDROGRAPH PROGRAM
COPYRIGHT 1992, 2001 RICK ENGINEERING COMPANY
RUN DATE 8/25/2016
HYDROGRAPH FILE NAME Text1
TIME OF CONCENTRATION 5 MIN. 1 ' 6 HOUR RAINFALL 2.5 INCHES
BASIN AREA 0.42 ACRES
( ' RUNOFF COEFFICIENT 0.9
(:';, ',~ PEAK DISCHARGE 2.49 CFS
(i"i',;) TIME (MIN)= 0 TIME (MIN) = 5
(I:'' TIME (MIN)= 10
"'" TIME (MIN)= 15
(". TIME (MIN) = 20
W TIME (MIN)= 25
a TIME (MIN)= 30
V TIME (MIN) = 35
•
TIME (MIN) = 40
TIME (MIN) = 45
•
TIME (MIN) = 50
TIME (MIN)= 55
•
TIME (MIN)= 60
TIME (MIN) = 65
•
TIME (MIN) = 70
TIME (MIN) = 75
•
TIME (MIN) = 80
TIME (MIN) = 85
TIME (MIN) = 90
• TIME (MIN) = 95
•
TIME (MIN)= 100
TIME (MIN)= 105
•
TIME (MIN)= 110
TIME (MIN)= 115
ll/flll\ TIME (MIN)= 120 w TIME (MIN)= 125
.,., TIME (MIN)= 130 w TIME (MIN)= 135
TIME (MIN) = 140 C TIME (MIN)= 145
..., TIME (MIN)= 150 w TIME (MIN)= 155
TIME (MIN)= 160 C TIME (MIN)= 165
TIME (MIN) = 170 C TIME (MIN) = 175
TIME (MIN)= 180 C TIME (MIN)= 185
TIME (MIN)= 190 C TIME (MIN)= 195
TIME (MIN) = 200 C TIME (MIN)= 205
TIME (MIN)= 210 C TIME (MIN)= 215
TIME (MIN)= 220 C TIME (MIN) = 225
TIME (MIN) = 230
• TIME (MIN) = 235
TIME (MIN) = 240
• TIME (MIN)= 245
TIME (MIN) = 250
• TIME (MIN) = 255
TIME (MIN) = 260
• TIME (MIN)= 265
TIME (MIN)= 270
• TIME (MIN)= 275
TIME (MIN) = 280
• TIME (MIN) = 285
TIME (MIN) = 290
•
TIME (MIN) = 295
TIME (MIN) = 300
•
TIME (MIN) = 305
TIME (MIN)= 310
•
TIME (MIN)= 315
TIME (MIN) = 320
•
TIME (MIN) = 325
TIME (MIN)= 330
•
TIME (MIN) = 335
TIME (MIN) = 340
TIME (MIN) = 345 C TIME (MIN) = 350 C TIME (MIN) = 355
,..
DISCHARGE (CFS)= 0
DISCHARGE (CFS)= 0.1
DISCHARGE (CFS) = 0.1
DISCHARGE (CFS) = 0.1
DISCHARGE (CFS) = 0.1
DISCHARGE (CFS)= 0.1
DISCHARGE (CFS)= 0.1
DISCHARGE (CFS) = 0.1
DISCHARGE (CFS) = 0.1
DISCHARGE (CFS) = 0.1
DISCHARGE (CFS) = 0.1
DISCHARGE (CFS)= 0.1
DISCHARGE (CFS)= 0.1
DISCHARGE (CFS)= 0.1
DISCHARGE (CFS)= 0.1
DISCHARGE (CFS) = 0.1
DISCHARGE (CFS) = 0.1
DISCHARGE (CFS)= 0.1
DISCHARGE (CFS) = 0.1
DISCHARGE (CFS)= 0.1
DISCHARGE (CFS) = 0.1
DISCHARGE (CFS) = 0.1
DISCHARGE (CFS) = 0.1
DISCHARGE (CFS) = 0.1
DISCHARGE (CFS)= 0.1
DISCHARGE (CFS) = 0.1
DISCHARGE (CFS)= 0.1
DISCHARGE (CFS)= 0.1
DISCHARGE (CFS) = 0.1
DISCHARGE (CFS) = 0.1
DISCHARGE (CFS)= 0.1
DISCHARGE (CFS)= 0.1
DISCHARGE (CFS) = 0.1
DISCHARGE (CFS)= 0.1
DISCHARGE (CFS)= 0.1
DISCHARGE (CFS)= 0.1
DISCHARGE (CFS)= 0.1
DISCHARGE (CFS)= 0.1
DISCHARGE (CFS) = 0.1
DISCHARGE (CFS) = 0.2
DISCHARGE (CFS) = 0.2
DISCHARGE (CFS) = 0.2
DISCHARGE (CFS) = 0.2
DISCHARGE (CFS)= 0.2
DISCHARGE (CFS) = 0.2
DISCHARGE (CFS) = 0.3
DISCHARGE (CFS) = 0.3
DISCHARGE (CFS) = 0.5
DISCHARGE (CFS)= 0.7
DISCHARGE (CFS) = 2.49
DISCHARGE (CFS)= 0.4
DISCHARGE (CFS) = 0.3
DISCHARGE (CFS)= 0.2
DISCHARGE (CFS) = 0.2
DISCHARGE (CFS) = 0.2
DISCHARGE (CFS) = 0.1
DISCHARGE (CFS)= 0.1
DISCHARGE (CFS)= 0.1
DISCHARGE (CFS)= 0.1
DISCHARGE (CFS)= 0.1
DISCHARGE (CFS) = 0.1
DISCHARGE (CFS) = 0.1
DISCHARGE (CFS) = 0.1
DISCHARGE (CFS) = 0.1
DISCHARGE (CFS)= 0.1
DISCHARGE (CFS) = 0.1
DISCHARGE (CFS) = 0.1
DISCHARGE (CFS)= 0.1
DISCHARGE (CFS)= 0.1
DISCHARGE (CFS)= 0.1
DISCHARGE (CFS)= 0.1
DISCHARGE (CFS)= 0.1
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C • • • • • • • • • C
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TIME (MIN) = 360
TIME (MIN) = 365
DISCHARGE (CFS)= 0.1
DISCHARGE (CFS)= 0
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SDHM 3.0
PROJECT REPORT
Biofiltration Planter -Stage/Storage/Discharge
Project Name: OCEAN CONDOMINIUMS
Site Address: 2501 STATE ST
City : CARLSBAD
Report Date: 8/25/2016
Name : BIOFILTRATION PLANTER
Surface Area: 1,285 square feet
Material thickness of first layer: 2
Material type for first layer: Sandy loam
Material thickness of second layer: 1
Material type for second layer: GRAVEL
Material thickness of third layer: O
Material type for third layer: GRAVEL
Underdrain used
Underdrain Diameter: 4 inches
Discharge Structure
Riser Height: 0.33 ft.
Riser Diameter: 12 in.
Hydraulic Table
Stas:e ( feet) Area(ac.) Volume(ac-ft.)
0.0000 0.0295 0.0000
0.5000 0.0295 0.0059
1.0000 0.0295 0. 0119
1.5000 0.0295 0.0178
2.0000 0.0295 0.0237
2.5000 0.0295 0.0299
3.0000 0.0295 0.0360
3.5000 0.0295 0.0507
Dischars:e(cfs)
0.0000
0.0019
0.0104
0.0301
0.0604
0.0700
0.0700
0.7235
CJ
C)
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0
0
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0
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1
Hyd rog ra Ph s Um ma ry Re po rtydraflow Hydrographs Extension for AutoCAD® Civil 30® 2009 by Autodesk, Inc. v6.066
Hyd. Hydrograph Peak Time Time to Hyd. Inflow Maximum Total Hydrograph
No. type flow interval peak volume hyd(s) elevation strge used description
(origin) (cfs) (min) (min) (cuft) (ft) (cuft)
1 Manual 2.490 5 245 3,717 ----------------Area A
3 Reservoir 0.723 5 250 3,582 1 13.50 2,207 Mitigated Flow
ocean planters.gpw Return Period: 100 Year Thursday, Aug 25, 2016
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•
Hydrograph Report
Hydraflow Hydrographs Extension for AutoCAD® Civil 30® 2009 by Autodesk, Inc. v6.066
Hyd. No. 1
Area A
Hydrograph type
Storm frequency
Time interval
a (cfs)
3.00
2.00
1.00
0.00
,_
,_
,
0.0
= Manual
= 100 yrs
= 5 min
,._
1.0
-HydNo.1
2.0
Peak discharge
Time to peak
Hyd. volume
Area A Unmitigated
Hyd. No. 1 --100 Year
~
-~-
-
--,_
I
3.0 4.0 5.0
•~
\
6.0
2
Thursday, Aug 25, 2016
= 2.490 cfs
= 4.08 hrs
= 3,717 cuft
a (cfs)
3.00
2.00
1.00
0.00
7.0
Time {hrs)
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Hydrograph Report
Hydraflow Hydrographs Extension for AutoCAD® Civil 30® 2009 by Autodesk, Inc. v6.066
Hyd. No. 3
Mitigated Flow
Hydrograph type
Storm frequency
Time interval
Inflow hyd. No.
Reservoir name
= Reservoir
= 100 yrs
= 5 min
= 1 -Area A
= Planters
Storage Indication method used .
Mitigated Flow
3
Thursday, Aug 25, 2016
I Peak discharge = 0.723 cfs
Time to peak = 4.17 hrs
Hyd. volume = 3,582 cuft
Max. Elevation = 13.50 ft
Max. Storage = 2,207 cuft
Q (cfs) Hyd. No. 3 --100 Year Q (cfs)
3.00 --,-----r----.------,.-----.------,.-----.------,.-----.--------..-3.00
0.00 ~~~~~l::::=~===d::==-.L..--L--L __ J_ o.oo
0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0 18.0
-HydNo.3 -HydNo.1 11111111111 Total storage used = 2,207 cuft Time (hrs)
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Pond Report
Hydraftow Hydrographs Extension for AutoCAD® Civil 30® 2009 by Autodesk, Inc. v6.066
Pond No. 1 -Planters
Pond Data
Pond storage is based on user-defined values .
Stage I Storage Table
Stage (ft) Elevation (ft) Contour area (sqft) Iner. Storage (cuft)
0.00 10.00 n/a 0
0.50 10.50 n/a 257
1.00 11.00 n/a 257
1.50 11.50 n/a 257
2.00 12.00 n/a 257
2.50 12.50 n/a 274
3.00 13.00 n/a 266
3.50 13.50 n/a 640
Total storage (cuft)
0
257
514
771
1,028
1,302
1,568
2,208
Culvert / Orifice Structures Weir Structures
[AJ [BJ [CJ [PrfRsrJ [AJ [BJ
Rise (in) = 0.00 0.00 0.00 0.00 Crest Len (ft) = 0.00 0.00
Span (in) = 0.00 0.00 0.00 0.00 Crest El. (ft) = 0.00 0.00
No. Barrels = 0 0 0 0 Weir Coeff. = 3.33 3.33
Invert El. (ft) = 0.00 0.00 0.00 0.00 Weir Type --
Length (ft) = 0.00 0.00 0.00 0.00 Multi-Stage = No No
Slope(%) = 0.00 0.00 0.00 n/a
N-Value = .013 .013 .013 nla
Orifice Coeff. = 0.60 0.60 0.60 0.60 Exfil.(in/hr) = 0.000 (by Wet area)
Multi-Stage = n/a No No No TW Elev. (ft) = 0.00
4
Thursday, Aug 25, 2016
[CJ [DJ
0.00 0.00
0.00 0.00
3.33 3.33
No No
Note: CulverVOrifice outflows are analyzed under inlet (ic) and outlet (oc) control. Weir risers checked for orifice conditions (ic) and submergence (s) .
Stage (ft)
4.00
3.00
,_
' 2.00
1.00 I
I
0.00
0.00 0.08
-Total Q
-
1-
-
0.16 0.24
Stage I Discharge
-
--~
I•-
-
0.32 0.40 0.48
-
, __
0.56 0.64 0.72
Elev (ft)
14.00
13.00
12.00
11.00
10.00
0.80
Discharge (cfs)