HomeMy WebLinkAboutAppendix F - Drainage StudyAppendix F
Drainage Study
1
DRAINAGE STUDY
FOR
FONTANA SQUARE
CITY OF FONTANA, CALIFORNIA
PREPARED BY:
ACE DESIGN LLC,
1024 IRON FRONT ROAD
FOLSOM, CA 95630
AUGUST 07, 2021
2
TABLE OF CONTENTS
1. INTRODUCTION: ............................................................................................................................. 3
2. SITE DESCRIPTION: ......................................................................................................................... 3
3. AREA BREAKUP: .............................................................................................................................. 3
4. TOPOGRAPHY: ................................................................................................................................ 3
5. RAINFALL: ....................................................................................................................................... 3
6. COEFFICIENT OF RUNOFF: .............................................................................................................. 4
7. DRAINAGE MANAGEMENT AREA: ................................................................................................. 4
8. DESIGN CAPTURE VOLUME (DCV): ................................................................................................ 6
9. BIO RETENTION VOLUME: .............................................................................................................. 6
10. CHECK FOR INFILTRATION OF THE PONDED VOLUME: ................................................................. 7
11. DRAINAGE NETWORK: ................................................................................................................... 7
APPENDIX 1 – VICINITY MAP
APPENDIX 2 – NOAA ATLAS 14, VOLUME 6, AND VERSION 2
APPENDIX 3 – WORKSHEET - H
APPENDIX 4 – SOIL INFILTRATION REPORT
APPENDIX 5 – GRADING PLAN
APPENDIX 6 – WATER QUALITY MANAGEMENT PLAN
3
DRAINAGE STUDY
1. INTRODUCTION:
The Scope of this drainage study is to quantify the Water Quality Control Volume required
by the project site and propose the Bio retention basins of the required capacity to treat
the storm runoff. The rainfall to be considered for calculation of the Water Quality Control
Volume is based on mean 6-hr precipitation. Water Quality volume is calculated based on
the City of Fontana, San Bernardino County Stormwater Program. Rainfall, Runoff
Coefficient, Drainage Management Area and Water Quality Volume are calculated in the
following sections.
2. SITE DESCRIPTION:
The proposed Commercial Development site is located south of Route 210, north of S
Highland Avenue, West of Catawba Avenue and east of Citrus Avenue in City of Fontana,
California as shown on the Vicinity Map, refer Appendix 1. The total area of the site is
386644 sf (8.876 acres). A Banquet Hall (1 story), Holiday Inn Express Hotel & Suites (104
rooms, 5 story), Staybridge Suites (117 rooms, 5 story), Restaurant (1 story) and an In-n-
out Burger Store (1 story) are proposed here.
There is an existing eccentric Cul-d-sac from Route-210 and power lines passing through
the project site. The City will relocate the Cul-d-sac and power lines out of the project
boundary.
3. AREA BREAKUP:
The proposed site plan consists of total paved area of 250,295 sf (5.746 acres), total
landscape area of 74,248 sf (1.70 acres) and building footprint of 62,130 sf (1.43 acres).
4. TOPOGRAPHY:
In present condition, the site is undeveloped and majority of the site drains in south
direction and there is an average fall of around 8-10 feet through the width of the site
towards South Highland Avenue. South Highland Avenue slopes from east to west. There
is an existing public storm drain facility on southeast corner of the site in Citrus Avenue,
however there are no public storm drain facilities in South Highland Avenue.
5. RAINFALL:
Rainfall depth is used for calculation of Mean 6-hr precipitation as per NOAA Atlas 14,
Volume 6, and Version 2. For LID BMP Design Capture Volume (DCV), the San Bernardino
4
County Stormwater Program requires use of the P6 method (MS4 Permit Section XI.D.6a.
ii) – Form 4.2-1.
Mean 6-hr precipitation is calculated as:
P6= (P2yr-1hr) * C1,
where C1 is a function of site climatic region, for valley = 1.4807, mountain = 1.909 and for
desert = 1.2371.
Mean 6-hr precipitation (P6) value comes 0.684 inches.
6. COEFFICIENT OF RUNOFF:
The coefficient of runoff has been calculated by using the following formula, for the
calculation of design capture volume.
Rc = 0.858(Imp%)3 - 0.78(Imp%)2 + 0.774(Imp%) + 0.04
where Imp% is the Imperviousness after applying preventive site design practices.
7. DRAINAGE MANAGEMENT AREA:
During earlier discussions held with the City, City informed to route majority of overflow
from Retention basins from the site to the existing public storm drainage facility on
southeast corner of the site. The grading for the project site and Bio Retention basins are
planned in such a way that overflow from Bio Retention basins from two third of the site
area is routed to the existing storm drain manhole, located in the South-East corner of the
site on Citrus avenue via a network of onsite storm drains.
Proposed Site is divided into six DMAs based on the proposed grades and location of
available landscaped/Green area.
DMA 1 – This 29,852 sf area consists of western half of the Banquet Hall building, Parking
and landscaped area in West part of the project site. This area is proposed to drain into
the landscape area along the Southern West corner. A bio retention area #1 of 1,490 sf
flat area without under drains is proposed in the landscaped area to provide the necessary
water quality treatment to the storm runoff. The overflow from this bio retention area is
proposed to drain to South-West corner of site to S Highland Avenue.
DMA 2 – This 84,552 sf area consists of eastern half of Banquet Hall building, western half
of Holiday Inn Express Hotel & Suites building, Parking and landscaped area of the project
site. This area is proposed to drain into the landscape area along the S Highland Avenue.
A bio retention area #2 of 2,992 sf flat area without under drains is proposed in the
landscaped area to provide the necessary water quality treatment to the storm runoff.
The overflow from this bio-retention area is proposed to drain to S Highland Avenue.
DMA 3 – This 53,325 sf area consists of eastern half of Holiday Inn Express Hotel & Suites
building, Parking and landscaped area of the project site. This area is proposed to drain
into the landscape area along the S Highland Avenue. A bio retention area #3 of 2085 sf
flat area without under drains is proposed in the landscaped area to provide the necessary
5
water quality treatment to the storm runoff. The overflow from this bio-retention area is
proposed to drain to S Highland Avenue.
DMA 4 – This 124,235 sf area consists of Staybridge Suites building, western portion of
Restaurant building, Parking and landscaped area in centre of the project site. This area is
proposed to drain into the landscape area along the S Highland Avenue. A bio-retention
area #4 of 4,790 sf flat area without under drains is proposed in the landscaped area to
provide the necessary water quality treatment to the storm runoff. The overflow from this
bio retention area will flow to onsite storm drain network connected to the existing
drainage manhole in the Southeast corner of project site in Citrus Avenue.
DMA 5 – This 14,652 sf area consists of northern portion of In-N-Out Burger Store building
and landscaped area in North-East corner of the project site. This area is proposed to drain
into the landscape area along the corner of Citrus Avenue. A bio retention area #5 of 940
sf flat area without under drains is proposed in the landscaped area to provide the
necessary water quality treatment to the storm runoff. The overflow from this bio
retention area will flow to onsite storm drain network connected to the existing drainage
manhole in the Southeast corner of project site in Citrus Avenue.
DMA 6 – This 71,924 sf area consists of southern portion of In-N-Out Burger Store building,
eastern portion of Restaurant building, Parking and landscaped area in eastern corner of
the project site. This area is proposed to drain into the landscape area along the
intersection of S Highland Avenue and Citrus Avenue. A bio retention area #6 of 3,790 sf
flat area without under drains is proposed in the landscaped area to provide the necessary
water quality treatment to the storm runoff. The overflow from this bio retention area
will flow to onsite storm drain network connected to the existing drainage manhole in the
Southeast corner of project site in Citrus Avenue.
The DMA’s and proposed grading are shown on WQM & Grading Plan. Refer Appendix-5
and 6 for Grading & Water Quality Management Plan.
DMA TOTAL AREA IMPERVIOUS AREA
(ROOF + PAVING)
PERVIOUS AREA
(LANDSCAPE)
1 29,850 22,620 7,230
2 84,552 68,491 16,061
3 53,325 42,670 10,655
4 124,235 102,904 21,331
5 14,652 7,835 6,817
6 71,924 59,770 12,154
6
8. DESIGN CAPTURE VOLUME (DCV):
Design Capture Volume (DCV) in cubic feet is determined by following expression
mentioned as per City Standards.
DCV = 1/12*(DMA area) * (Runoff coefficient, Rc) * (Mean 6-hr Precipitation, P6) * C2,
Where C2 is a function of drawdown rate (for 48-hr = 1.963)
DMA TOTAL AREA
(IN SF)
IMPERVIOUSNESS
RATIO
RUNOFF
COEFFICIENT
(Rc)
MEAN 6-HR
PRECIPITATION
(IN INCHES)
DESIGN CAPTURE
VOLUME
(IN CUBIC FEET)
1 29,850 0.76 0.552 1.01 2,730
2 84,552 0.81 0.611 1.01 8,562
3 53,325 0.80 0.600 1.01 5,297
4 124,235 0.83 0.635 1.01 13,061
5 14,652 0.53 0.363 1.01 881
6 71,924 0.83 0.637 1.01 7,590
9. BIO RETENTION VOLUME:
Bio retention areas in all the six DMAs are proposed to provide the required water quality
treatment. The required retention is proposed to be provided by the amended soil having
porosity of 15% and by gravel volume provided below the soil having a porosity of 35%. A
varying ponding depth of 1.0’-1.25’ is provided over the flat area of all the basins. A free
board of 0.5’ is provided for all the basins. An infiltration rate of underlying soils is 5.75
in/hr and 10.20 in/hr at the depth of 5.0’ and 10.0’ respectively per infiltration report on
dated July 20, 2021. Minimum infiltration value of 5.75 in/hr used for calculations.
Infiltration safety factor of 2.2 is calculated from Worksheet H per city standards. Thus,
the design percolation rate calculated for the soil is 2.61 in/hr. A typical 3-hr duration of
storm is considered for filing the retention basins as per Form 4.3-3 from Water Quality
Management Plan Template.
DMA
#
AREA OF
DMA (IN
SF)
BIO -
RETEN
TION #
FLAT
AREA
(IN
SF)
FREE -
BOARD
DEPTH
(IN
FEET)
PONDING
DEPTH
(IN FEET)
DEPTH OF
AMENDED
SOIL (IN
FEET)
PORO
SITY
OF
SOIL
GRAVEL
DEPTH
(IN
FEET)
POROSITY
OF
GRAVEL
VOLUME
REQUIRED
(IN CUBIC
FEET)
VOLUME
PROVIDED
(IN CUBIC
FEET)
1 31,750 1 1,490 0.5 1.0 1.5 0.15 1.0 0.35 2,730 3,320
2 82,640 2 2,992 0.5 1.25 1.5 0.15 2.25 0.35 8,562 8,724
3 53,325 3 2,085 0.5 1.25 1.5 0.15 1.25 0.35 5,297 5,350
4 124,235 4 4,790 0.5 1.25 1.5 0.15 1.75 0.35 13,061 13,129
5 13,895 5 940 0.5 1.0 1.5 0.15 1.0 0.35 881 2,095
6 72,705 6 3,790 0.5 1.0 1.5 0.15 1.0 0.35 7,590 8,446
7
10. CHECK FOR INFILTRATION OF THE PONDED VOLUME:
Considering a design infiltration rate of 2.61 inch /hour the retained volume will infiltrate
into the ground within 48 hours as shown below for all the Bio-retention basins.
BASIN PROVIDED
VOLUME (IN CF)
FLAT AREA
(IN SF)
DESIGN INFILTRATION
RATE (IN
INCHES/HOUR)
DRAWDOWN TIME
(IN HOURS)
1 3,320 1,490 2.61 10
2 8,724 2,992 2.61 13
3 5,350 2,085 2.61 12
4 13,129 4,790 2.61 13
5 2,095 940 2.61 10
6 8,446 3,790 2.61 10
11. DRAINAGE NETWORK:
Overflow from Bio Retention basins 1, 2 and 3 is proposed to be drained through under
sidewalk drains to S Highland Avenue and overflow from Bio Retention basins 4, 5 and 6
is proposed to be connected to the onsite storm drainage network. Onsite network is
proposed to be connected to existing public storm drainage network on southeast corner
of the site in Citrus Avenue. For Storm drain pipeline alignment and invert levels refer
Appendix-5 Grading Plan.
APPENDIX - 1
VICINTY MAP
NORTHPROJECT
APPENDIX - 2
NOAA ATLAS 14,
VOLUME 6, AND
VERSION 2
APPENDIX – 3
WORKSHEET-H
VII-35 May 19, 2011
Worksheet H: Factor of Safety and Design Infiltration Rate and Worksheet
Factor Category Factor Description
Assigned
Weight (w)
Factor
Value (v)
Product (p)
p = w x v
A Suitability
Assessment
Soil assessment methods 0.25
Predominant soil texture 0.25
Site soil variability 0.25
Depth to groundwater / impervious
layer 0.25
Suitability Assessment Safety Factor, SA = p
B Design
Tributary area size 0.25
Level of pretreatment/ expected
sediment loads 0.25
Redundancy 0.25
Compaction during construction 0.25
Design Safety Factor, SB = p
Combined Safety Factor, STOT= SA x SB
Measured Infiltration Rate, inch/hr, KM
(corrected for test-specific bias)
Design Infiltration Rate, in/hr, KDESIGN = STOTKM
Supporting Data
Briefly describe infiltration test and provide reference to test forms:
Note: The minimum combined adjustment factor shall not be less than 2.0 and the maximum
combined adjustment factor shall not exceed 9.0.
1
2
25
50
21
:25.6+((7+
5.75
APPENDIX – 4
SOIL INFILTRATION REPORT
APPENDIX – 5
GRADING PLAN
SLOPEFF=1501.00FF=1502.50
FF=1505.00FF=1505.50
FF=1506.50TRASHENCLOSURE08/12/2021LSDSC22REVISIONS:CHK. BY:TITLE
PROJECTDWG. BY:DATE:JOB :SHEETPhone: (702) 396-5113, Fax: (702)446-8155
Land Planning Civil Engineering Architectural Design Structural Engineering
ACE Design LLCACE Design LLC
FOLSOM, CA 95630
1024 IRON POINT ROAD OF 04FONTANA SQUARE
NWC CITRUS & S. HIGHLAND AVE.
FONTANA, CALIFORNIA19-03PROJECT
APPENDIX – 6
WATER QUALITY MANAGEMENT PLAN
FF=1501.00FF=1502.50
FF=1505.00FF=1505.50
FF=1506.50SITTING AREAPATIOPOOL AREAOUT DOORFRONT PORCHPORTECOCHEREPOOLPATIOOUTDOOR
SLOPE08/12/2021LSDSC44REVISIONS:CHK. BY:TITLE
PROJECTDWG. BY:DATE:JOB :SHEETPhone: (702) 396-5113, Fax: (702)446-8155
Land Planning Civil Engineering Architectural Design Structural Engineering
ACE Design LLCACE Design LLC
FOLSOM, CA 95630
1024 IRON POINT ROAD OF 04FONTANA SQUARE
NWC CITRUS & S. HIGHLAND AVE.
FONTANA, CALIFORNIA19-03PROJECT