3284831
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FINAL HYDROLOGY &
HYDRAULICS REPORT
for
Traci
City of La Quinta
March 31,'2008
Prepared for:
Sevak Khatchadourian
137 South Reeves Dr., Suite 303
Beverly Hills, Ca 90212
Phone: (310) 560 -1688
Fax: (310) 858 -1397
Prepared by:
Terra Solutions, Inc.
2280. Market St., Ste 220
Riverside, CA 92501
Phone: (951) 328 -0400
Fax: (951) 328 -0401
Prepared under the supervision of:
Juan nuel Sanchez, P.E. RCE 30846 Exp. 03 -31 -10
'1 i I I -%
3
0)-o)p
A.- 100 and 10 Year Rational Method AMC II, Developed Condition
B.- W.S.P. G. W. for 24' pipe
C.- Street capacity calculation
D.- Catch basin calculations
E.= Unit Hydrograph shortcut method: 100 year storm, 3 hour duration.
- In tract
Off site
F.- Retention basins calculation
In tract
Off site
G.- Hydrology Map
In tract
Off site
el
Table of Contents
r� Introduction
Purpose
Methodology
Findings
Summary
Subsequent Hydrology
Hydrology Exhibits
Exhibit No. 1:
Flows for pre- developed condition
Exhibit No. 2:
Flows for developed condition after level of water reaches the
spillway.
Exhibit No. 3:
Sections A A, and B B
Exhibit 4A:
Drainage Map City of La Quinta
Exhibit S:
1,000 year storm factors
In -Tract Hydrology and Hydraulic Calculations
A.- 100 and 10 Year Rational Method AMC II, Developed Condition
B.- W.S.P. G. W. for 24' pipe
C.- Street capacity calculation
D.- Catch basin calculations
E.= Unit Hydrograph shortcut method: 100 year storm, 3 hour duration.
- In tract
Off site
F.- Retention basins calculation
In tract
Off site
G.- Hydrology Map
In tract
Off site
el
L ) Introduction
Tentative Tract Map 32848 is a 5.2 -acre subdivision, consisting of 15 ten thousands
t square foot lots, located on the north side of Avenue 60, west of Madison Street, in the
City of La Quinta, County of Riverside, California. An ultimate master plan storm drain
system does not exist downstream or adjacent to the property, therefore the proposed
storm drain system for the subdivision will convey the majority of the on -site storm water
runoff to a proposed retention basin at the north (lowest) end of the subdivision. This
retention basin will be designed to hold at least the 100 year storm.
A smaller retention basin at the south -east corner of the subdivision, will pick up the off
site flows from the adjacent street (Avenue 60). This retention basin will hold at least the
100 year off -site storm event. Off -site meaning that portion of Avenue 60 adjacent to the
subdivision, the 20 feet wide landscape area and the basin itself.
Therefore the retention basins will hold at least 100% of the 100 -year storm runoff at the
developed condition.
The existing drainage pattern of the site sheet flows to the north -east, (see Exhibit No. 1).
After the retention basins are in place, there will be no flows during the 100 year storm
onto the property to the north, (see exhibit No. 3, section A -A).
In the case of a more severe storm (greater than 100 -year storm) the basin will have
additional capacity to hold up to the 1,000 year storm and will also comply with the City
of La Quinta requirement of one foot of freeboard. After the spillway elevation (462.5) at
�1 the major retention basin is reached, the spillway will direct the flows to the northerly
property as a sheet flow, similar to the presently existing condition, (see Exhibit No. 2). It
is necessary to reiterate that in the 100 -year event, no flows will spill over onto the
property to the north.
The same design concept was used for the smaller retention basin located at the southeast
portion of the subdivision, adjacent to Avenue 60. This retention basin is designed to hold
at least the 100 -year storm runoff produced by the off -site portion of Tract No. 32848.
Also in case of severe storm the basin has the capacity to hold up to 1,000 year storm
event. A modified curb drain will be installed in front of the basin on Avenue 60 to
collect the offsite flows and direct them into the basin. After the spillway elevation is
reached (474.74), an overflow swale will convey the storm water runoff back to Avenue
60. Under normal conditions of functioning the retention basin will hold the at least 100 -
year storm runoff, (see Exhibit No. 3 section B -B).
Purpose
The purpose of this Preliminary Hydrology Report is to determine storm water runoff for
the site. It is also to show that drainage systems, comprised of proposed streets, catch
basins, storm drain pipelines and retention basins are adequately sized. Hydraulic
calculations for the storm drain systems and catch basins are included in this report along
with the hydrology exhibits.
According to the City of La Quinta Engineering Bulletin #06 -16 for Retention basin
design, the Synthetic Unit Hydrograph Analysis (short cut method) should be used for
projects smaller than 100 acres and lag time lower than 7 minutes. The retention basin(s)
shall be designed to hold the 100 year, 3 hour duration storm.
Methodology
D The rational method, as outlined by the current Riverside County Flood Control
Hydrology Manual, is used to determine the 100 -year and 10 -year event storm water
runoff (Q).
Retention basins are designed to hold the 100 year, 3 hour duration storm.
Calculations are performed using the short cut synthetic hydrograph method from the
Riverside County Flood Control Hydrology Manual.
One foot of freeboard is built into the retention basin, as required by the City Engineering
Bulletin for Hydrology, in order to minimize the potential of flooding onto the properties
downstream and in this case northerly of the subdivision.'
Please note that no infiltration was considered at the floor of the retention basin(s).
Recommended values for infiltration rates will be used in the final Hydrology Report
after percolation testing is performed at the site, prior to Final Engineering.
Computer programs such as CivilD, AES and W.S.P.G.W. are utilized herein.
Findings
17V-TRACT— The proposed interior tract street adequately conveys the 100 -year and 10-
year storm run -off, towards the proposed in tract retention basin. .
A Storm drain pipeline system will be constructed with one catch basin at the north end
of the cul -de -sac to convey the in -tract flows to the retention basin at the north end. A 24
inches RCP will be used to convey the water from the catch basin to the retention basin
W.S.P.G.W. is provided for the 24" pipe.
Street capacity calculations are provided for the 10 years storm event.
OFF -SITE — The existing Avenue 60 will convey the off -site flows to the small retention
basin located on the north -east corner of the tract though a modified curb inlet.
Summary
The on -site street (cul -de -sac) and storm drain system proposed for the subdivision will
adequately convey the 100 year and 10 year event storm water runoff to the proposed
retention basin.
The volume necessary for the on -site retention basin without infiltration for the 100 year,
3 hour duration storm is calculated to be 0.73 Ac -ft (31,583 cf).
The volume needed for the off -site retention basin without. infiltration for the 100 year, 3
hour duration storm is calculated to be 0.09 Ac -ft (3,814 cf).
The two basins in this case will be designed to hold 100% of the 1,000 year storm as a
factor of safety beyond the recommended 100 year storm. In order to obtain the values
for 1,000 year storm the 100 year storm values have been multiplied by 1.45. See
Riverside County Flood Control and Water Conservation District Hydrology Manual,
F` ' page B -2 on Exhibit No. 5
In tract retention basin (At the northerly property line)
Elevation for the bottom of the retention basin = 457.00 ft
Elevation of the spillway =
462.50 ft
Elevation of the 100 year storm =
460.14 ft
Elevation of 1,000 year storm =
461.20 ft
Freeboard for 1,000 year+
1.30 ft
Storm event Maximum water elevation
Volume
Freeboard
year ft
cu -ft
ft
100 460.14
32,029
2.36
1,000 461.20
47,817
1.30
up to spillway 462.50
69,836
0.00
VOLUME REQUIRED 100 YEAR STORM = 31,583 CF
VOLUME REQUIRED 1,000 YEAR STORM = 45,795 CF
Off site retention basin (At Avenue 60)
Elevation for the bottom of the retention basin = 472.50 ft
Elevation of the spillway = 474.74 ft
Elevation of the 100 year storm = 473.3-8 ft
Elevation of 1;000 year storm= 473.74 ft
Freeboard for 1,000 year= 1.35 ft
Storm event Maximum water elevation Volume Freeboard
year ft cu -ft ft
100 473.38 3,932. 1.36
1,000 473.74 5,752 1.00
up to spillway 474.74 11,026 0.00
VOLUME REQUIRED 100 YEAR STORM = 3,814 CF
VOLUME REQUIRED 1,000 YEAR STORM = 5,530 CF
Subsequent hydroloQy
This hydrology and hydraulic report is preliminary in nature for locating and sizing the
retention and should be taken as such. It will be followed by a subsequent report(s) as the
preliminary grading is updated and changed and as final design moves forward. The final
hydrology may change, to a minor extent, including the storm drain system configuration,
sizing, etc.
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EXHIBIT No. 1
BRUSH t
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x4"S&7 467.7
947a4 x
4613 464.4
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GRAPHIC SCALE
0 50 100
SCALE: 1"=100' FLOWS FOR PREDEVELOPED CONDITION
AT THE NORTH PROPERTY LINE
ft
EXHIBIT No. 2
A VE)VUt --, VO
N,
GRAPHIC SCALE
0 50 100
j FLOWS FOR DEVELOPED CONDITION
AFTER LEVEL OF WATER REACHES THE SPILLWAY
SCALE: 1"=100' (SEE SECTION A —A IN EXHIBIT No. 3)
AT THE NORTH PROPERTY LINE
EXHIBIT No. 3
LOTS LOT
200'
46
PAD EL =4650
R£T. WALL R.
LOTD
70.74'
6274'
461.20 - -1000 YR DEMON LEVEL
— 460.14 - -100 YR D£S/GN L£VFL
24.74'
SECTION 'A -A'
NTS
R/W LINE LOT LINE
10' 1 20'
TC AND SWALE END LOT B
U1FZ0
£LEV.= 474.65 O
I SWAB I I 474.74
AVE 60 0� OUTFLO
CURB DRAIN
. INV. = 474.30 MODIF1E0 CURB DRAIN—"
INLET (BEYOND)
LOT F
TRACT BDRY
TOP OF BERM 463.00'
SPILLWAY 46250'
NORTHERLY PROPERTY
DOST. GROUND SURFACE
FREEBOARD
1.00' FREEBOARD 47510
473.74 - -1000 >R DESIGN LEVEL
473.38 - -100 >R DESIGN LEVEL
LOT LINE LOT 15
475.8 PAD Ee
VARIES (FROM 38' TO 47) I BOTTOM �
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NTS
WALL
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Spillway Storm Precipitation - As discussed in the Introduction
Section of this report, spillway design is normally for something
between the 1000 -year and the probable maximum precipitation (PMP) storm.
In development of spillway hydrology :all available rainfall records in
and near the watershed should be analyzed. For preliminary planning
purposes only, spillway precipitation amounts can be estimated using 100--
year precipitation times the factors in the following tabulation:'
Return Period
(Std. Deviations *)
1,000 -Year
(5.1 to 5.9)
10,000 -Year
(6.9 to 8.2)
10 Std. Deviations
(10)
PMP
(15)
Spillway Precipitation Factors
Ratio to the 100 -Year Event
Santa Ana Santa Margarita Whitewater
River Basin River Basin River Basin
1.35
1.37
1.45
1.68
1.73
1.89
2.27
2.22
2.24
3.22
3.15
3.21
*Approximate number of standard deviations above the mean. See DWR Bulletin
Number 195.
The tabulated factors above are based on methods presented in Depart-
ment of Water Resources (DWR) Bulletin Number 195, "Rainfall Analysis for
Drainage Design," dated October 1976. It should be emphasized that these
factors are suitable for preliminary planning purposes only, and selection
of design precipitation values for spillways requires an in -depth analysis
of all available records and the pertinent literature.
District Frequency Analyses - The District has prepared frequency
analyses for records of all available precipitation stations in and near
Othe District. These analyses are based on methods described by DWR in
B -2
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C-10
)EX NUMBERS" OF HYDROLOGIC SOIL - COVER rr)MIDr.�
Cover' Type ( 3 )
.NATURAL COVERS. -
Barren
(Rockland, eroded and graded land)
Chaparrel, Broadleaf
(Manzonita, ceanothus and scrub. oak)
Chaparrel; Narrowleaf
(.Chamise and redshank)
Grass, Annual or Perennial
Meadows or Cienegas
(Areas.with seasonally high water table,
Principal vegetation is-sod forming grass)
Open Brush
(Soft wood shrubs - buckwheat, sage, etc.)
woodland
(Coniferous-or broadleaf trees predominate.
Canopy density is at least 50 Percent)
Woodland, Grass
(Coniferous or broadleaf trees with canopy
density from 20 to 50 percent)
URBAN COVERS -
Residential or Commercial Landscaping
(Lawn, shrubs, etc.)
Turf
(Irrigated and mowed.grass)
AGRICULTURAL COVERS
Fallow
(Land plowed but not tilled or seeded)
RCFC a WCD
I HYDROLOGY. MANUAL
FOR PERVIOUS. AREAS -AMC II
Quality . of Soil Group
Cover (2) B C D
Poor
Fair
Good
Poor
Fair
Poor
Fair
Good
Poor
Fair
Good
Poor
Fair
Good
Poor
Fair
Good
Poor
Fair
Good
Poor
Fair..,
Good
RUNOFF INDEX
FOR
PERVIOUS
78 186 .I 91 1.93
53
70
80
85
40
63
75
81
31
57
182
71
78
191
71
88
55
72
81
86
67
78
86
89
50
69
79
84
38
. 61
74
80
63
77
85
88
51
70
80
.84
30
58
72
78
62
76
84
88
46
66
77
83
41
63
75
177
81
45
66
83
36
60
73
79
28
55
70
77
57.
73
82
86
44
65
77.
82
33
58
72
79
32 156 169 175
58 174..*l 8 3 87 44 65 77' 82
33 58 72 79
76 85 90 92
NUMBERS
AREAS
PLATE E -6.1 0 of 2)
Riverside County Rational Hydrology Program
CIVILCADD /CIVILDESIGN Engineering Software,(c) 1989 - 2005 Version 7.1
Rational Hydrology Study. Date: 05/24/07 File:rr.out
----------------------------------------------------------------------
RATIONAL METHOD
100 YEAR STORM
TTM 32348, LA QUINTA, CALIFORNIA
IN SITE FLOWS
------------------------ ----------------------------------------------
********* Hydrology Study Control Information * * * * * * * * **
English (in -lb) Units used in input data file
Program License Serial Number 6019
----------------------------------------------------------7-------------
Rational Method Hydrology Program based on
Riverside County Flood Control & Water Conservation District
1978 hydrology manual
Storm event (year) = 100.00 Antecedent Moisture Condition = 2
Standard intensity- duration curves
For the [ Palm Springs ] area used
10 year storm 10 minute intensity
10 year storm 60 minute intensity
100 year storm 10 minute intensity
100 year storm 60 minute intensity
data (Plate D -4.1)
2.830(In /Hr)
1.000(In /Hr)
= 4.520(In /Hr)
= 1.600(In /Hr)
Storm event year = 100.0
Calculated rainfall intensity data:
1 hour intensity = 1.600(In /Hr)
Slope of intensity duration curve = 0.5800
+++++++++++++++++++++++++++++++++++++++ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + ++
Process from Point /Station 10.000 to Point /Station 20.000
* * ** INITIAL AREA EVALUATION * * **
Initial area flow distance = 213.000(Ft.)
Top (of initial area) elevation = 77.000(Ft.)
Bottom (of initial area) elevation = 67.900(Ft.)
Difference in elevation = 9.100(Ft.)
Slope = 0.04272 s(percent)= 4•.27
TC = k(0.390) *[(length ^3) /(elevation change)] ^0.2
Initial area.time of concentration = 6.256 min.
Rainfall intensity = 5.937(In /Hr) for a 100.0 year storm
i
SINGLE FAMILY (1/4 Acre Lot)
Runoff Coefficient = 0.833
Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 1.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 0.000
RI index for soil(AMC 2) = 56.00
Pervious area fraction = 0.500; Impervious fraction = 0.500
Initial subarea runoff = 7.118(CFS)
Total initial stream area = 1.440(Ac.)
Pervious area fraction = 0.500
+++++++++++++++++++++++++++++++++++++++ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + ++
Process from Point /Station 20.000 to Point /Station 30.000
* * ** STREET FLOW TRAVEL TIME + SUBAREA FLOW ADDITION * * **
Top of street segment elevation = 67.900(Ft.)
End of street segment elevation = 62.400(Ft.)
Length of street segment = 310.000(Ft.)
Height of curb above gutter flowline = 6.0(In.)
Width of half street (curb to crown) = 18.000(Ft.)
Distance from crown to crossfall grade break = 10.000(Ft.)
Slope from gutter to grade break (v /hz) = 0.020
Slope from grade break to crown.(v /hz) = 0.020
Street flow is on (2] side(s) of the street
Distance from curb to property line = 10.000(Ft.)
Slope from curb to property line (v /hz) = 0.020
Gutter width = 1.500(Ft.)
Gutter hike from flowline = 0.125(In.)
j Manning's N in gutter = 0.0150
Manning's N from gutter to grade break = 0.0150
Manning's N from grade break to crown = 0.0150
Estimated mean flow rate at midpoint of street = 12.770(CFS)
Depth of flow = 0:254(Ft.), Average velocity = 3.441(Ft /s)
Streetflow hydraulics at midpoint of street travel:
Halfstreet flow width = 13.675(Ft.)
Flow velocity = 3:44(Ft /s)
Travel time = 1.50 min. TC = 7.76 min.
Adding area flow to street
SINGLE FAMILY (1/4 Acre Lot)
Runoff Coefficient = 0.825
Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 1.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 0.000
RI index for soil(AMC 2) 56.00
Pervious area fraction = 0.500; Impervious fraction = 0.500
Rainfall intensity = 5.241(In /Hr) for a 100.0 year storm
Subarea runoff = 11.199(CFS) for 2.590(Ac.)
Total runoff = 18.317(CFS) Total area = 4.030(Ac.)
Street flow at end of street = 18.317(CFS)
Half street flow at end of street = 9.159(CFS)
Depth of flow = 0.293(Ft.), Average velocity = 3.767(Ft/s)
Flow width (from curb towards crown)= 15.639(Ft.)
+++++++++++++++++++++++++++++++++++++++ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + ++
Process from Point /Station 30.000 to Point /Station 40.000
* * ** PIPEFLOW TRAVEL TIME (Program estimated size) * * **
Upstream point /station elevation = 62.400(Ft.)
Downstream point /station elevation = 57.000(Ft.)
Pipe length = 49.83(Ft.) Manning's N = 0 -.013
No. of pipes = 1 Required pipe flow = 18.317(CFS)
Nearest computed pipe diameter = 15.00(In.)
Calculated individual pipe flow = 18.317(CFS)
Normal flow depth in pipe = 10.73(In.)
Flow top width inside pipe = 13.53(In.)
Critical depth could not be calculated.
Pipe flow velocity = 19.49(Ft /s)
Travel time through pipe = 0.04 min.
Time of concentration (TC) = 7.80 min.
+++++++++++++++++++++++++++++++++++++++ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + ++
Process from Point /Station 40.000 to Point /Station 40.000
* * ** SUBAREA FLOW ADDITION * * **
UNDEVELOPED (poor cover) subarea
Runoff Coefficient = 0.840
Decimal fraction soil group A = 0.000
'Decimal fraction soil group B = 1.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = .0.000
RI index for soil(AMC 2) = 78.00
Pervious. area fraction = 1.000; Impervious fraction = 0.000
\ y Time of concentration = 7.80 min.
J Rainfall intensity = 5.224(In /Hr) for a 100.0 year storm
Subarea runoff = 2.369(CFS) for 0.540(Ac.)
Total runoff = 20.686(CFS) Total area = 4.570(Ac.)
End of computations, total study area = 4.57 (Ac.)
The following figures may
be used for a unit hydrograph study of the same area.
Area averaged pervious area fraction(Ap) = 0.559
Area averaged RI index number 58.6
01 Riverside County Rational Hydrology Program
CIVILCADD /CIVILDESIGN Engineering Software,(c) 1989 - 2005 Version 7.1
Rational Hydrology Study Date: 05/24/07 File:rr.out
------------------------------------------------------------------------
RATIONAL METHOD
10 YEAR STORM
TTM 32348, LA QUINTA, CALIFORNIA
IN SITE FLOWS
------------------------------------------------------------------------
********* Hydrology Study Control Information * * * * * * * * **
English (in -lb) Units used in input data file
Program License Serial Number 6019
------------------------------------------------------------------------
Rational Method Hydrology Program based on
Riverside County Flood Control & Water Conservation District
1978 hydrology manual
Storm event (year) = 10.00 Antecedent Moisture Condition =.2
Standard intensity- duration curves
For the [ Palm Springs ] area used
10 year storm 10 minute intensity
10 year storm 60 minute intensity
100 year storm 10 minute intensity
100 year storm 60 minute intensity
data (Plate D -.4.1)
2.830(In %Hr)
1.000(In /Hr)
.4.520(In /Hr)
1.600(In /Hr)
Storm event year = 10.0
Calculated rainfall intensity data:
1 hour intensity = 1.000(In /Hr)
Slope of intensity duration curve = 0.5800
++++++++++++++++++++++++++++++++++±++++ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + ++
Process from Point /Station 10.000 to Point /Station 20.000
* * ** INITIAL AREA EVALUATION * * ** .
Initial area flow distance = 213.000(Ft.)
Top (of initial area) elevation = 77.000(Ft.)
Bottom (of initial area) elevation = 67.900(Ft.)
Difference in elevation = 9.100(Ft.)
Slope = 0.04272 s(percent)= 4.27
TC = k (0.390) *[(length ^3) /(elevation change)] ^0.2
Initial.area time of concentration = 6.256 min.
Rainfall intensity = 3.711(In /Hr) for a 10.0 year storm
SINGLE FAMILY (1/4 Acre Lot)
Runoff Coefficient = 0.801
C
C/
Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 1.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 0.000
RI index for soil(AMC 2) = 56.00
Pervious area fraction = 0.500; Impervious fraction = 0.500
Initial subarea runoff = 4.280(CFS)
Total initial stream area = 1.440(Ac.)
Pervious area fraction = 0.500
+++++++++++++++++++++++++++++++++++++++ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + ++
Process from Point /Station 20.000 to Point /Station 30.000
* * ** STREET FLOW TRAVEL TIME + SUBAREA FLOW ADDITION * * **
Top of street segment elevation = 67.900(Ft.)
End of street segment elevation = 62.400(Ft.)
Length of street segment = 310.000(Ft.)
Height of curb above gutter flowline = 6.0(In.)
Width of half street (curb to crown) = 18.000(Ft.)
Distance from crown to crossfall grade break = 10.000(Ft.)
Slope from gutter to grade break (v /hz) = 0.020
Slope from grade break to crown (v /hz) = 0.020
Street flow is on [2] side(s) of the street
Distance from curb to property line = 10.000(Ft.)
Slope from curb to property line (v /hz) = 0.020
Gutter width = 1.500(Ft.)
Gutter hike from flowline = 0.125(In.)
Manning's N in gutter = 0.0150
Manning's N from gutter to grade break = 0.0150
Manning's N from grade break to crown = 0.0150
Estimated mean flow rate at midpoint of street = 7.650(CFS)
Depth of flow = 0.207(Ft.), Average velocity = 3.025(Ft /s)
Streetflow hydraulics at midpoint of street travel:
Halfstreet flow width = 11.310(Ft.)
Flow velocity = 3.03(Ft /s)
Travel time = 1.71 min. TC = 7.96 min.
Adding area flow to street
SINGLE FAMILY (1/4 Acre Lot)
Runoff Coefficient = 0.790
Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 1.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 0.000
RI index for soil(AMC 2) = 56.00
Pervious area fraction = 0.500; Impervious fraction
Rainfall intensity = 3.226(In /Hr) for a 10.0
Subarea runoff = 6.598(CFS) for 2..590(Ac.)
Total runoff = 10.878(CFS) Total area =
Street flow at end of street = 10.878(CFS)
Half street flow at end of street =. 5.439(CFS)
= 0.500
year storm
4.030(Ac.)
Depth of flow = 0.238(Ft.), Average velocity = 3.305(Ft /s)
Flow width (from curb towards crown)= 12.885(Ft.)
+++++++++++++++++++++++++++++++++++++++ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + ++
Process from Point /Station 30.000 to Point /Station 40.000
C`
* * ** PIPEFLOW TRAVEL TIME (Program estimated size) * * **
Upstream point /station elevation = 62.400(Ft.)
Downstream point /station elevation = 57.000(Ft.)
Pipe length = 49.83(Ft.) Manning's N = 0.013
No. of pipes = 1 Required pipe flow = 10.878(CFS)
Nearest computed pipe diameter = 12.00(In.)
Calculated individual pipe flow = 10.878(CFS)
Normal flow depth in pipe = 9.14(In.)
Flow top width inside pipe = 10.22(In.)
Critical depth could not be calculated.
Pipe flow velocity = 16.96(Ft /s)
Travel time through pipe = 0.05 min.
Time of concentration (TC) = 8.01 min.
+++++++++++++++++++++++++++++++++++++++ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + ++
Process from Point /Station 40.000 to Point /Station 40.000
* * ** SUBAREA FLOW ADDITION * * **
UNDEVELOPED (poor cover) subarea
Runoff Coefficient = 0.806
Decimal fraction soil group A = 0..000
Decimal fraction soil group B = 1.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 0.000
RI index for soil(AMC 2) = 78.00
Pervious area fraction = 1.000; Impervious fraction = 0.000
Time of concentration = 8.01 min.
Rainfall intensity = 3.215(In /Hr) for a 10.0 year storm
Subarea runoff = 1.399(CFS) for 0.540(Ac.)
Total runoff = 12.277(CFS) Total area = 4.570(Ac.)
End of computations, total study area = 4.57 (Ac.)
The following figures may
be used for a unit hydrograph study of the same area.
Area averaged pervious area fraction(Ap) = 0.559
Area averaged RI index number = 58.6
Riverside County Rational Hydrology Program
CIVILCADD /CIVILDESIGN Engineering Software,(c) 1989 - 2005 Version 7.1
Rational Hydrology Study Date: 05/23/07 File:RR1.out
------------------------------------------------------------------------
RATIONAL METHOD
100 YEAR STORM
TTM 32348, LA QUINTA, CALIFORNIA
OFF SITE FLOWS
------------------=-----------------------------------------------------
********* Hydrology Study Control Information * * * * * * * * **
English (in- lb).Units used in input data file
Program License Serial Number 6019
------------------------------------------------------------------------
Rational Method Hydrology Program based on
Riverside County Flood Control & Water Conservation District
1978 hydrology manual
Storm event (year) = 100.00 Antecedent Moisture Condition = 2
Standard intensity- duration curves data (Plate D -4.1)
For the [ Palm Springs ] area used.
10 year storm 10 minute intensity = 2.830(In /Hr)
10 year storm 60 minute intensity = 1.000(In /Hr)
100 year storm 10 minute intensity = 4.520(In /Hr)
100 year storm 60 minute intensity = 1.600(In /Hr)
Storm event year = 100.0
Calculated rainfall intensity data:
1 hour intensity = 1.600(In /Hr)
Slope of intensity duration curve = 0.5800
+++++++++++++++++++++++++++++++++++++++ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + ++
Process from Point /Station 100.000 to Point /Station 200.000
* * ** INITIAL AREA EVALUATION * * **
Initial area flow distance = 340.000(Ft.)
Top (of, initial area] elevation = 78.860(Ft.)
Bottom (of initial area) elevation = 74.300(Ft.)
Difference in elevation = 4.560(Ft.)
Slope = 0.01341 s(percent)= 1.34
TC = k (0.300) *[(length ^3) /(elevation change)] ^0.2
Initial area time of concentration = 7.315 min.
j Rainfall intensity = 5.423(In /Hr) for a 100.0 year storm
COMMERCIAL subarea type
Runoff Coefficient = 0.885
Decimal fraction soil group.A = 0.000
Decimal fraction soil group B = 1.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 0.000
RI index for soil(AMC 2) 56.00
Pervious area fraction = 0.100; Impervious fraction = 0.900
Initial subarea runoff = 1.632(CFS)
Total initial stream area = 0.34,0(Ac.)
Pervious area fraction = 0..100
End of computations, total study area = 0.34 (Ac.)
The following figures may
be used for a unit.hydrograph study of the same area.
Area averaged pervious area fraction(Ap) = 0.100
Area averaged RI index number = 56.0
I FM-
ti
0
a Riverside County Rational Hydrology Program
CIVILCADD /CIVILDESIGN Engineering Software,(c) 1989 2005 Version 7.1
Rational Hydrology Study Date:'05 /23/07 File:RR1.out
------------------------------------------------------------------------
RATIONAL METHOD
10 YEAR STORM
TTM 32348, LA QUINTA, CALIFORNIA
OFF SITE FLOWS
------------------------------------------------------------------------
********* Hydrology Study Control Information * * * * * * * * **
English (in -lb) Units used in input data file
Program License Serial Number 6019
------------------------------------------------------------------------
Rational Method Hydrology Program based on
Riverside County Flood Control & Water Conservation District
1978 hydrology manual
Storm event (year) = 10.00 Antecedent Moisture Condition = 2
Standard intensity- duration curves
For the [ Palm Springs ] area used
10 year .storm 10 minute intensity
10 year storm 60 minute intensity
100 year storm 10 minute intensity
100 year storm 60 minute intensity
data (Plate D -4.1)
2.830(In /Hr)
1.000(In /Hr)
= 4.520(In /Hr)
= 1.600(In /Hr)
Storm event year = 10.0
Calculated rainfall intensity data:
1 hour intensity = 1.000(In /Hs)
Slope of intensity duration curve = 0.5800
+++++++++++++++++++++++++++++++++++++++ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + ++
Process from Point /Station 100.000 to Point /Station .200.000
* * ** INITIAL AREA EVALUATION * * **
Initial area flow distance = 340.000(Ft.)
Top (of initial area) elevation = 78.860(Ft.)
Bottom (of initial area) elevation = 74.300(Ft.)
Difference in elevation = 4.560(Ft.)
Slope = 0.01341 s(percent)= 1:34
TC = k(0.300) *[(length ^3) /(elevation change)] ^0.2
Initial area time of concentration = 7.315 min.
Rainfall intensity = 3.389(In /Hr) for a 10.0 year storm
j COMMERCIAL subarea type
Runoff Coefficient = 0.879
Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 1.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 0.000
RI index for soil(AMC 2) = 56.00
Pervious area fraction = 0.100; Impervious fraction = 0.900
Initial subarea runoff = 1.013(CFS)
Total initial stream area = 0.340(Ac.)
Pervious area fraction = 0.100
End of computations, total study area 0.34 (Ac.)
The following figures may
be used for a unit.hydrograph study of the same area.
Area averaged pervious area fraction(Ap) = 0.100
Area averaged RI index number = 56.0
adTd «fZ Aof �41'J'd'S�fl (8
01
J
T1 TTM 32348, LA QUINTA 0
T2 PIPE FROM NODE 30 TO NODE 40
T3 100 YEAR STORM
SO 1000.000 57.000 1 62.500
R 1049.830 58.840 1 .013 .000
WE 1049.830 58.840 2• .500
SH 1049.830 58.840 2 58.840
CD 1 4 1 .000 2.000 .000 .000 .000 .00
CD 2 2 0 .000 4.000 10.0 .000 .000 .00
Q 18.317 .0
j0
FILE: savak.WSW
W S P G W- CIVILDESIGN Version
14.06
PAGE 1
Program Package Serial Number: 1837
WATER SURFACE PROFILE LISTING
Date: 5 -24 -2007
Time:11:22:
3
TTM 32348, LA QUINTA
PIPE FROM NODE 30 TO NODE 40
100 YEAR STORM
I Invert I
Depth I Water I Q I Vel Vel I Energy I
Super
ICriticallFlow ToplHeight /IBase Wtl
INo Wth
Station I Elev I
(FT) I Elev I (CFS) I (FPS) Head I Grd.El.l
Elev
I Depth I Width Ibia. -FTIor I.D.1
ZL
.IPrs /Pip
L /Elem ICh Slope I
I I I SF Avel HF ISE DpthlFroude
NINorm Dp I "N" I X -Fall)
ZR
IType Ch
1000.000 57.000
5.500 62.500 18.32 5.83 .53 63.03
.00
1.54 .00 2.000 .000
.00
1 .0
-I- -I-
49.830 .0369
-I- -I- -I- -I- -I- -1-
.0066 .33
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5.50
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1049.830 58.840
3.987 62.827 18.32 5.83 .53 63.35
.00
1.54 .00 2.000 .000
.00
1 .0
WALL ENTRANCE
I I
1049.830 58.840
I I I I I
4.775 63.615 18.32 .38 .00 63.62
.00
I I I I I
.47 10.00 4.000 10.000
.00
I
0 .0
capacity Street
MF
R/W
uj
m 'R /W
0.5'
SECTION A-A
NTS .
I
MANNING"S EQUATION
1.486 x A x R x S4
n
-In Which
Q = Flow rate (cfs)
A = Area of water normal to flow (ffl
radius (ft)
S ='.Slope of the street (ft /ity
n Roughness coefficient
For - section A—A
A = 6.74 ft2
R = 0,088 ft
S = 0.0118 ft/ft
n = .0.015
'14.2' cfs > %0
wpnnp rHPP
O
O�
0
/
' % W
L'u
Catch Basin No.2 Q
Flow —by Con ition
/ :ON SITE STREET CAPACITY CALCULATION
SECTION A -A
/
l'
Catch Basin No.1.
A ump Condition
- -- W = 10�_ —
— — — — — — — — — — — —
/ W — 4'
o rii
i
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k
i
I
suoyv1na1vd uzsv4 �13lvj (Q
IJV
{
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fs88S= d
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A: _
(�J-bs) 81/,01 X /I - 6uruado- jo na.ay = y
10- 9 x d x
l '9N NISVff HJ-Z VJ
NDjT1 IQNOS dHnSS
NLr7 -T1 d 7/S 7 V NIS dE - h!S1 Vi ` "T
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-� J SL '0 7
07 ON ffJ JOY
<sf>> a. o,a looly ajn� doh - = a
J), ursoq q4 of j 66 PIA = OA
y�iyM u1.
87
= 0141
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7'
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= 0141
0 'ON. SNIS d8 1-101 d,?
C (cis)
.00
SO
EXAMPLE (See 000ed Line)
G+vm 0- 66cfs
S. 10.0y. .
Find 0 ■ a.ss ft.
A - 4.8 ft2
GYM
)O pppp
0.67�dlGV
I
R/W
30'
1 18,
'o
,,.Uqu
0(cfs)
zoo-=-
100
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40
30
20 lt0
O50 =057
(Xtfs)
;x-20
�. �e)
�0
o.1o�a.17
.10
a7� -aso
THE C DETERMINED FROM THIS CHART.
IS FOR ONE HALF OF STREET.
LOS ANGELES COUNTY ROAD DE-PARTMEN— T
STREET FLOW REFERENCE SHEET
LOCAL ST.- Chart I of I
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u4 ! AVERAGE AUJUS I ED • L.U5.5 HA I E • Fizo"Socc.,��
113
C51
C73
CO]
C93
121 133
(",
SOL
GROUP
COVER RI
TYPE NUMBER
PERVIOUS
AREA
LAND
USE'
DECIMAL
PERCENNT
1OF
ADJUSTED
INFILTRATION
AREA'
96•Ni6WbS
AH
ADJUSTED
G ,
(PLATE C -11
(PLATE E-6.1)
INFILTRATION
RATE -IN /HR
AREA
IMPERVIOUS
RATE -IN /HR
C4]( 1- .9[67)
pp
Pkc4eS
INFILTRATION
RATE -IN /HR
1
C d
( PLATE 6.2)
( PLATE E -6.3)
C7 ]r C9]
r-
3-4- a�well A�. • �...
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o: z39
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4.61 O.Z3a
Eta]- Et1o]-
,VAR -1 ABLE LOSS RATE CURVE ( 24. —HOUR STORM ONLY
F m = Minimum Loss Rate = F/2 =1 CI03/2 IN ./HR.
o
C = (F —Fm) /S4 -' =
� 1.65 ,
FT =C(24. (T /60))I'5d +F = IN./HR.
Yrl (24 —(T /6011 'I'
Where:/
T =Time in minutes. To gef an average value for each unit time period,Use T= 2 the unit time for the
first time period T =1 Z unit time for . the second period etc.
I �
�C,
R C F C& W C D
SYNTHETIC UNIT HYDROGRAPH METHOD
PToj6ct
shut
HYDROLOGY
Unit Hydrogroph and Effective Rain
1114
By Cla t�
MANUAL
Calculation. Form
Checked Date__
113 CONCENTRATION POINT tAobr- 4co
123 AREA DESIGNATION
C33 DRAINAGE AREA -SQ MILES 0,O0-11
C43 ULTIMATE DISCHARGE - CFS - HRS /IN (645+[3])
153 UNIT TIME - MINUTES $
C6] LAG TIME - MINUTES
[7J UNIT TIME - PERCENT OF LAG (100+[5] /C63)
183 S -CURVE
193 STORM FREQUENCY C DURATION 400 YEAR- 3 HOUR
1103 TOTAL ADJUSTED STORM RAIN - INCHES 2.(Co
[11] VARIABLE LOSS RATE (AVG)- INCHES /HOUR
1121 MINIMUM LOSS RATE (FOR VAR. LOSS) -IN /HR
1133 CONSTANT LOSS RATE - INCHES /HOUR
1143 LOW LOSS.-RATE-PERCENT cto
UNIT HYDROGRAPH
EFFECTIVE RAIN
FLOOD
C15]
1163 C171 C183 C193
120] C21 3 1221 1233
YDROGRAPH
1243
UNIT
TIME
TIME CUMULATIVE DISTRIB NIT
PERCENT AVERAGE GRAPH HYDROGRAPH
PATTERN STORM LOSS EFFECTIVE
PERCENT RAIN RATE
FLOW
PERIOD
t►L
OF LAG PERCENT OF PERCENT FS- HRS /IN
17] +115] DISCHARGE [I73C17] C4]i008J
RAIN
(PL E -5.9 IN /HR IN /HR IN /HR
O
CFS
1213-1221
100
(S -GRAPH )
MAX LOW
•
0.31'Z, C2o1
i
1.3
0,401,
o.2y
�
0.11
Z
o,4ob
O.-Li
-
0, ►-{
3
t.1
0.343
0.10-
5
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0.4b6
6
1.6
o,sve.
Ott
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6
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t.6
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C 562
10
15
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-
0.13
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oz4
o.Zb
tZ
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o.56Z
a2�
0,32
13
2.1
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45
2.2
0.68
at
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18
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4.60
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3:3
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22
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1.310
0. -L*
27
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X.s 60
0,-L+
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3S
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1.f3
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04.
0.1v1
o.z
2� 2.-Z. 65
IN TRACT
Effective rain = 22.65n/hr. x 5/60 hr
= 1.89 inches
Flood Volume = Effective rain x area
= 1.88 in x 1/12 x 4.61 Ac.
= 0.73 Ac -ft
31,583 cf
1,000 year storm for Whitewater basin = 1.45 x 100 year storm
Flood volume for 1,000 year storm = 1.45 x 31,583 cf = 45,795 cf
H
.qq
m
m
N
N
0
-w
N
AVL.V
f AUL AUJU5.1-t`tr?
LUZ).S 11A I
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121 C33
U] C51
171 CB]
C93
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501E COVER RI .. ERV
GROUP TYPE NUMBER AREA
OUS LAND
USE
DECIMhL ADJUSTED 'AREA' -
PERCENNT INFILTRATION wiaellam
AVERAGE
F ADJUSTED
)> q C
( PLATE C-1) ( PLATE E-6.11 I N F I I
RATE
TRAT I ON
=INVHR
OF AREA RATE - I N /HR Ac,�+tS .
IMPERVIOUS C43l l- .9C6])
E -6.3)
I NF I L T RATION
17]r19]
Z O
( PLATE
f+.2)
(PLATE
I-
I
14.61
5
. a0,
0.0 Ar
o 0
0-A S1
0.0 Wf
r` K
510
.Si
0PJIWN•
to
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w7
UA)Iii.
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azi
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O.us
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f ^CD
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P
M
0
o
o
7
a
ECe] -_ o Ll ECio]- 0.101
D
T►
VARI ABLE LOSS RATE
CURVE ( 24. —HOUR STORM ONLY)
U
FM= Minimum Loss Rate=— F/2 =10011/2=
IN. /HR. •
g g
C = (F - Fyn) /54 ' _ (f CIO
FT = C( 24-( T /60))155 +Fm(24-
(T /60))" "+ IN./HR.
Where:
4
T =Time in minutes. To get an average
value for each unit time period,Use T= 2 the unit time for the
first time period, T' = I- unit time f
r. the second period, etc.
i.c
R C F C IS W C D
sYNTHETIC UNIT HYDROGRAPH METHOD
Project
ShNt
HYDROLOGY
Unit Hydro9roph and Effective Rain
OFF T ZNC.T
By Dote
MANUAL
Calculation Form
Chocked Date_
113 CONCENTRATION POINT
123 AREA DESIGNATION 35,
C3 ] DRAINAGE AREA -SO MILES 0.000
E43 ULTIMATE D I SCHARGE- CFS - HRS / I N ( 645# C3 3 )
153 UNIT TIME - MINUTES 5
161 LAG TIME- MINUTES
C73'UNIT TIME- PERCENT OF LAG (100#[53 /C63)
181 S -CURVE
193 STORM FREQUENCY C DURATION 100 YEAR- 3 HOUR
1103 TOTAL ADJUSTED STORM RAIN - INCHES Z,(o
1113 VARIABLE LOSS RATE (AVG)- INCHES /HOUR
1123 MINIMUM LOSS RATE (FOR VAR. LOSS) -IN /HR
1133 CONSTANT LOSS RATE- INCHES /HOUR O.Z9lo
1143 LOW LOSS-•RATE- PERCENT ego
UNIT HYDRO GRAPH
EFFECTIVE RAIN
LOOD
1153
1161 1173 1183 1191
C203 E2 13 1223 1233
YDROGRAPH
124]
UNIT
TIME
TIME CUMULATIVE DISTRIB NIT
PERCENT AVERAGE GRAPH qYDROGRAPH
PATTERN STORM LOSS EFFECTIVE
PERCENT RAIN
FLOW
PERIOD
trl
OF LAG PERCENT OF PERCENT FS- HRS /'IN
173#[157 073V C073W.,1143#C18]
RATE RAIN
(PL E -5.9 IN /HR IN /HR. IN /HR
0
CFS
DISCHARGE
100
121] -C22]
100 L5 j
IS-GRAPH)
MAX LOW
O•'6lZ bo
1.3
0.406
0.30
Z
1.3
0.406
0.30
-
O, 11
3
1.1
0,543
01*0
-
0.0s
4 I
O,yb
0.30
-
0.11
5
1.S
o. *>b
0.3o
-
o.11
b
18
OS61.
0.30.
17
1 S
0.%%
0.30
-
'0• l7
8
l•8
O Sbt
0(30
9
I.t3
O.SeZ
0.30
0.%"
0,.30
o t"1
0.4-99
c 3o
-
0.20
1b
1.1&
0.56Z
0.30
1�
2.1
O.roBb
o30
-
o.3q
14
2.2
0. (f%
0.,ao
-
0.36I
15
2.1
o 66b
D.30
tb
2. o
a 102*
0.30
t-1
.2•b
0.811
0.30
t6
Z.'1
0,642
0:30
19
2.t+
o -I 49
0.'w
70
2.1
0,642
0.30
I - T
0 SS
zl
31!0
1.030
0.30
I - -
0:13
0.30
-
of.-1
23
Z.q
o..goS
o 30
-
o.t,1
2
10
0.64
2S
.A
0A101
b.(,7 f
2b
'�•-L
1.310
0.3o
28
Zg
2113
31
0.2
2.5-lb
o.30
0.30
-
1.SS
33
.2.AT0
35
1
1.0
O.�Z
0.30
-
0,21
36
D•30
- 1
0.0
2�0, 6l in�Inr
OFF SITE
Effective rain = 20.67 in/hr. x 5/60 hr
= 1.72 inches
Flood Volume = Effective rain x area
= 1.72 in x 1/12 x 0.61 Ac.
1 1 • : it
3,814 cf
1,000 year storm for Whitewater basin = 1.45 x 100 year storm
Flood volume for 1,000 year storm = 1.45 x 3,814 cf = 5,530 cf
C)
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Elevation
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458.0
459.0
460.0
461.0
461.5
Height
Ft
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1.0
2.0
3.0
4.0
4.5
Area
Sq ft
6,989
8,940
10,983
13,117
15,343
16,486
Volume
Cf
7,964
9,961
12,050
14,230
7,957
Elevation for the bottom of the retention basin =
Elevation of the spillway =
Elevation of the 100 year storm =
Elevation of 1,000 year storm =
<J
Accumulate Volume
Cft.
7,964
17,925
29,975
44,205
52,162
457.00 ft
462.50 ft
460.14 ft
461.20 ft
LOT LINE LOT D TRACT BDRY
LOT 8 70.74
2 00' 62.74' 6.00''
FF ELEV. 461.20- -1000 YR DESIGN LEVEL i TOP OF BERM 463.00'
= 465:50 464.50 460.14- -100 YR DESIGN LEVEL SPILL WA Y 462.50'
NOR THERL Y PROPERTY
EXIST GROUND SURFACE
PAD EL. =465. 0 ? - , o
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"> > /.�j / /.���/ �j� / /�� �• 1.30' FREEBOARD
24.74' 457.00'
BOTTOM
SECTION "A -A"
NTS
Off site retention basin
Elevation
Height
Area
Volume
Accumulate Volume
Ft
Ft
Sq ft
Cf
Cft
472.5
0.0
3,803
2,015
2,015
473.0
0.5
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4, 752
6,767
474.0
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5,779
12,546
475.0
2.5
6,311
641
.13,186
475.1
2.6
6,505
Elevation for the bottom. of the retention basin = 472.50 ft
•� Elevation of the spillway = 474, 74 ft
Elevation of the 100 year storm = 473.38 ft
Elevation of 1,000 year storm = 473.74 ft
TC AND SWALE END
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AVE 60
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10' - - 20' - I
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023 1 340
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I i PP(k? PET. BASN
I I I OMM/UND ` COMMERCIAL/UNDEVELOPED
j
LOT F 15 I 14 I 13 I 12 I 11 I 10 9 I I
2.11348 LINEAL LI E L FEET OF FLOW
! I
PRO DRAINAGE I I I I I I I ACREAGE (AC)
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11 PPF No. 1
— — — — — — — — — — — COMMERCIAL /UNDEVELOPED
O
- ;- - - - -- ----- - --- --
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_ r 1 r, J., INDICATES DRAINAGE FLOW
I
J ��J I INDICATES HYDROLOGY NODE
III i
4 I I XXXX.X INDICATES ELEVATION
! WATERSHED BOUNDARY
SOUTH NORTH
R/W I DEPRESS FINISHED R/W LOT LINE APPLICANT /OWNER: HP HIGH POINT
60' SURFACE 1.5 20•
SEVAK KHATCHADOURIAN
30' 30' LANDSCAPE SETBACK LOT 137 SOUTH REEVES DRIVE, SUITE 303
10' 6' i 14' 20' 10' 10. 1 BEVERLY HILLS, CA 90212
FUTURE TUR 1 1 3' r H - 1 1
2X
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22 I 2X A.0
........': "' :!,,, 10' MEANDERING
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C.A.B.
60TH AVENUE
NO SCALE
SOIL TYPE V
SOIL TYPE V
is
r-
l4 .
FINAL HYDROLOGY MAP DEVELOPED CONDITION AMENDED TRACT No. 32848
B
R/4l o�
0.5'+
BE R/W
LOCAL INTERIOR STREET
NTS
R/W I DEPRESS FINISHED R/W LOT LINE
60' SURFACE 1.5"---,, 20'
30' 30' LANDSCAPE SETBACK LOTI
10' 6' 14' 20' 1 lo. 1 10
D.5' FUTURE UTUR
�10.EANDERIN.
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CONC CURB STD. NO. 260
3" A.C. OVER 4.5" Ec GUTTER
WEDGE CURB IMPROVEMENTS C.A.B.
60TH AVENUE
NTS
VICINITY MAP
NOT TO SCALE
GRAPHIC SCALE
0 15 30
u s a
SCALE: 7'
N D E . --- UNDEVELOPED
ACREAGE (AC)
3— 4 —3 -4 DWELLING PER ACRE
2.11 -
ACREAGE (AC)
—� INDICATES DRAINAGE FLOW
Q INDICATES HYDROLOGY NODE
XXXX.X INDICATES ELEVATION
WATERSHED BOUNDARY
HP HIGH POINT
APPLICANT /OWNER:
SEVAK KHATCHADOURIAN
137 SOUTH REEVES DRIVE, SUITE 303
SOIL TYPE ,?B„ BEVERLY HILLS, CA 90212
PRELIMINARY HYDROLOGY MAP DEVELOPED CONDITION AMENDED TRACT N o. 32848
OFF -SITE DRAINAGE
I
i
05
/
/
/
/
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I 19.5' 19.5' I ( 10' 6' 14' 20' 10� I 10'
1 9 , 19, I FUTURE FUTUR 3' I
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2.0% s® _ _- •- co LEVEL LINE TC 1.
— — :,�� „��� rn Y �, tea: ".`. CONC CURB STD. NO. 260
-;
i!; _! —: !
.,:. • ...• ..,,, .,. 3” A.C. OVER 4.5"' &GUTTER
IMPROVEMENTS C.A.B.
6" WEDGE CURB
LOCAL INTERIOR STREET
NTS
60TH AVENUE
NTS
SAIL TYPE 'Bp
VICINITY MAP
NOT TO SCALE
GRAPHIC SCALE
0 15 30
IN
SCALE: 1"=30'
LEGEND:
0MM/UN� �— COMMERCIAL /UNDEVELOPED
2,11348 LINEAL FEET OF FLOW
ACREAGE (AC)
COMMERCIAL /UNDEVELOPED
2.11 LINEAL FEET OF FLOW
ACREAGE (AC)
INDICATES DRAINAGE FLOW
10 INDICATES HYDROLOGY NODE
XXXX.X INDICATES ELEVATION
WATERSHED BOUNDARY'.
APPLICANT /OWNER: HP HIGH POINT
SEVAK KHATCHADOURIAN
137 SOUTH REEVES DRIVE, SUITE 303
BEVERLY HILLS, CA 90212
TERRA SOLUTIONS, INC.
ENGINEERING • PLANNING 0 SURVEYING
2280 Market Street
Suite 220 Office 951 •328.0400
Riverside, CA 92501 Fax 951 •328.0401
PRELIMINARY HYDROLOGY MAP
DEVELOPED CONDITION OFF -SUE DRAINAGE
PREPARrwy�x sio SUPERVISION OF: DATE:
JUL, 2007
DRAWN BY.
El
DESIGN BY:
Exp. -0Q. � ED
E
* JOB NO.
J.M. ANCHEZ, J . EXP. DATE: 3 -31 -08 SHEET
R.C.E. NO. 30846 2 of 2
PRELIMINARY HYDROLOGY MAP DEVELOPED CONDITION AMENDED TRACT No. 32848
�f
I 19.5' 19.5'
I 19'
19' I
I I
38'
3' 16.5'
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FUTCIRE FUTUR 3' I
—�-I �•.- -- 29° -•---
IMPROVEMENTS C.A.B.
60TH AVENUE
NTS
SOIL TYPE �B�
'� ��' .
VICINITY MAP
NOT TO SCALE
GRAPHIC SCALE
0 15 30
���
SCALE: 1 " =30'
LEGEND
-F— UNDEVELOPED
ACREAGE (AC)
3 -4 -�3 -4 DWELLING PER ACRE
2.11 -
ACREAGE (AC)
` '`' INDICATES DRAINAGE FLOW
10 � INDICATES HYDROLOGY NODE
XXXX.X INDICATES ELEVATION
WATERSHED BOUNDARY
HP HIGH POINT
APPLICANT /OWNER: . .
SEVAK KHATCHADOURIAN
137 SOUTH REEVES DRIVE, SUITE 303
BEVERLY HILLS, CA 90212 ,
TERRA SOLUTIONS, INC.
ENGINEERING • PLANNING • SURVEYING
2280 Market Street
Suite 220 Off ice 951 •328.0400
Riverside, CA 92501 Fax 951 •328.0401
PRELIMINARY HYDROLOGY MAP
DEVELOPED CANDRION IN TRACT DRAINAGE
PREPARED UN o � ERVISION OF: JDUL�2007
gP�NC � DRAWN BY:
EI
m DESIGN BY:
� ED
� JOB N0.
. ANCHEZ, JR. � XP. DATE: 3 -31 -08 SHEET
R.C.E. N 0. 30846 � of 2
�' "' `�'
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&GUTTER
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60TH AVENUE
NTS
SOIL TYPE �B�
'� ��' .
VICINITY MAP
NOT TO SCALE
GRAPHIC SCALE
0 15 30
���
SCALE: 1 " =30'
LEGEND
-F— UNDEVELOPED
ACREAGE (AC)
3 -4 -�3 -4 DWELLING PER ACRE
2.11 -
ACREAGE (AC)
` '`' INDICATES DRAINAGE FLOW
10 � INDICATES HYDROLOGY NODE
XXXX.X INDICATES ELEVATION
WATERSHED BOUNDARY
HP HIGH POINT
APPLICANT /OWNER: . .
SEVAK KHATCHADOURIAN
137 SOUTH REEVES DRIVE, SUITE 303
BEVERLY HILLS, CA 90212 ,
TERRA SOLUTIONS, INC.
ENGINEERING • PLANNING • SURVEYING
2280 Market Street
Suite 220 Off ice 951 •328.0400
Riverside, CA 92501 Fax 951 •328.0401
PRELIMINARY HYDROLOGY MAP
DEVELOPED CANDRION IN TRACT DRAINAGE
PREPARED UN o � ERVISION OF: JDUL�2007
gP�NC � DRAWN BY:
EI
m DESIGN BY:
� ED
� JOB N0.
. ANCHEZ, JR. � XP. DATE: 3 -31 -08 SHEET
R.C.E. N 0. 30846 � of 2
LANDMARK
a DBE MBE/SBE Company
March 30, 2005
Mr. Sevak Kachadurian
Prudential California Realty
9696 Wilshire Boulevard
Beverly Hills, CA 90212
LGeotechnical Investigation
P d idLeatial-H pment
APN 766 - 080 -008
La Quinta. California
LCI Report No. LP05046
Dear Mr. Kachadurian:
780 N. 4th Street
El Centro, CA 92243
(760) 370 -3000
(760) 337 -8900 fax
77 -948 Wildcat Drive
Palm Desert, CA 92211
(760) 360 -0665
(760) 360 -0521 fax
This geotechnical report is provided for design and construction of the proposed residential
development located near the northwest corner of Avenue 60 and Madison Street south of La Quinta,
California. Our geotechnical investigation was conducted in response to your request for our
services. The enclosed report describes our soil engineering investigation and presents our
professional opinions regarding geotechnical conditions at the site to be considered in the design and
construction of the project.
The findings of this study indicate the site is underlain by interbedded sandy silts and silty sands.
The subsurface soils are loose to medium dense in nature. Groundwater was not encountered in the
borings during the time of field exploration.
Severe sulfate levels were not encountered in the soil samples tested for this study. However the soil
is highly corrosive to metal. We recommend a minimum of 2,500 psi concrete of Type Il Portland
Cement with a maximum water /cement ratio of 0.60 (by weight) should be used for concrete placed
in contact with native soils of this project.
We did not encounter soil conditions that would preclude implementation of the proposed project
provided the recommendations contained in this report are implemented in the design and
construction of this project. Our findings, recommendations, and application options are related only
through reading the full report, and are best evaluated with the active participation of the engineer
of record who developed them.
Proposed Residential Development — La Quinta, CA LCI Report No. LP05046
We appreciate the opportunity to provide our findings and professional opinions regarding
geotechnical conditions at the site. If you have any questions or comments regarding our findings,
please call our office at (760) 360 -0665.
Respectfully Submitted,
Landmark Consultants, Inc.
lTordme�yer Kel y
Staff eologist
r
Greg . Chan Ta, P
Princi 1 Engi eer
�, OQ "OFESSION
G M.
C9 o�
E C No. C 34432
EXPIRES 09 -30-05
C
'�al hafiqul Alam
Staff Engineer
Proposed Residential Development — La Quinta, CA LCI Report No. LP05046
TABLE OF CONTENTS
Page
Section1 ............................................................................................................ ..............................1
INTRODUCTION......................................................................................... ..............................1
1.1 Project Description ............................................................................. ..............................1
1.2 Purpose and Scope of Work ............................................................... ..............................1
1.3 Authorization ...................................................................................... ..............................2
Section2 ............................................................................................................ ..............................3
METHODS OF INVESTIGATION .............................................................. ..............................3
2.1 Field Exploration ................................................................................ ..............................3
2.2 Laboratory Testing ............................................. ............................... ..............4
..................
Section3 ............................................................................................................ ...................:..........5
DISCUSSION................................................................................................ ..............................5
3.1 Site Conditions ................................................................................... ..............................5
3.2 Geologic Setting ................................................................................. ..............................5
3.3 Seismicity and Faulting ...................................................................... ..............................6
3.4 Site Acceleration and CBC Seismic Coefficients ............................... ..............................7
3.5 Subsurface Soil ................................................................................... ..............................8
3.6 Groundwater ....................................................................................... ..............................8
Section4 ............................................................................................................ ..............................9
RECOMMENDATIONS.............................................................................. ............................... 9
4.1 Site Preparation ................................................................................... ..............................9
4.2 Foundations and Settlements ............................................................. .............................11
4.3 Slabs -On -Grade ................................................................................. .............................12
4.4 Concrete Mixes and Corrosivity ........................................................ .............................13
4.5 Excavations ........................................................................................ .............................14
4.6 Lateral Earth Pressures ...................................................................... .............................14
4.7 Seismic Design .................................................................................. .............................15
4.8 Pavements .......................................................................................... .............................15
Section5 ........................................................................................................... .............................17
LIMITATIONS AND ADDITIONAL SERVICES ...................................... .............................17
5.1 Limitations ......................................................................................... .............................17
5.2 Additional Services ............................................................................ .............................18
APPENDIX A:
Vicinity and Site Maps
APPENDIX B:
Subsurface Soil Logs and Soil Key
APPENDIX C:
Laboratory Test Results
APPENDIX D:
References
Proposed Residential Development — La Quinta, CA LCI Report No. LP05046
Section 1
INTRODUCTION
1.1 Project Description
This report presents the findings of our geotechnical investigation for the proposed residential
development located on Avenue 60 south of La Quinta, California (See Vicinity Map, Plate A -1).
The proposed development will consist of one to two story single family residences on
approximately 5- acres. A site plan for the proposed development was not made available to us at the
time that this report was prepared.
The structures are planned to consist of continuous footing with slabs -on -grade and wood -frame
construction. Footing loads at exterior bearing walls are estimated at 1 to 3 kips per lineal foot.
Column loads are estimated to range from 5 to 15 kips. If structural loads exceed those stated above,
we should be notified so we may evaluate their impact on foundation settlement and bearing
capacity. Site development will include building pad preparation, underground utility installation,
street construction, and concrete driveway and sidewalk placement.
1.2 Purpose and Scope of Work
The purpose of this geotechnical study was to investigate the upper 51.5 feet of subsurface soil at
selected locations within the site for evaluation of physical /engineering properties. From the
subsequent field and laboratory data, professional opinions were developed and are provided in this
report regarding geotechnical conditions at this site and the effect on design and construction. The
scope of our services consisted of the following:
► Field exploration and in -situ testing of the site soils at selected locations and depths.
► Laboratory testing for physical and/or chemical properties of selected samples.
► Review of the available literature and publications pertaining to local geology,
faulting, and seismicity.
► Engineering analysis and evaluation of the data collected.
► Preparation of this report presenting our findings, professional opinions, and
recommendations for the geotechnical aspects of project design and construction.
Landmark Consultants, Inc. Page 1
` Proposed Residential Development — La Quinta, CA LCI Report No. LP05046
This report addresses the following geotechnical issues:
► Subsurface soil and groundwater conditions
► Site geology, regional faulting and seismicity, near source factors, and site seismic
accelerations
► Aggressive soil conditions to metals and concrete
Professional opinions with regard to the above issues are presented for the following:
P. Site grading and earthwork
► Building pad and foundation subgrade preparation
► Allowable soil bearing pressures and expected settlements
► Concrete slabs -on -grade
► Lateral earth pressures
► Excavation conditions and buried utility installations
► Mitigation of the potential effects of salt concentrations in native soil to concrete
mixes and steel reinforcement
► Seismic design parameters
► Pavement structural sections
Our scope of work for this report did not include an evaluation of the site for the presence of
environmentally hazardous materials or conditions.
1.3 Authorization
Mr. Sevak Kachadurian of Prudential California Realty provided authorization by written agreement
to proceed with our work on February 22, 2005. We conducted our work according to our written
proposal dated February 9, 2005
Landmark Consultants, Inc. Page 2
Proposed Residential Development — La Quinta, CA LCI Report No LP05046
Section 2
METHODS OF INVESTIGATION
2.1 Field Exploration
Subsurface exploration was performed on February 28, 2005 using Williams Drilling of Indio,
California to advance four (4) borings to depths of 14.0 to 51.5 feet below existing ground surface.
The borings were advanced with a truck- mounted, CME 55 drill rig using 8 -inch diameter, hollow -
stem, continuous -flight augers. The approximate boring locations were established in the field and
plotted on the site map by sighting to discernable site features. The boring locations are shown on
the Site and Exploration Plan (Plate A -2).
A staff geologist observed the drilling operations and maintained a log of the soil encountered and
sampling depths, visually classified the soil encountered during drilling in accordance with the
Unified Soil Classification System, and obtained drive tube and bulk samples of the subsurface
materials at selected intervals. Relatively undisturbed soil samples were retrieved using a 2 -inch
outside diameter (OD) split -spoon sampler or a 3 -inch OD Modified California Split - Barrel (ring)
sampler. The samples were obtained by driving the sampler ahead of the auger tip at selected depths.
The drill rig was equipped with a 140 -pound CME automatic hammer for conducting Standard
Penetration Tests (SPT). The number of blows required to drive the samplers 12 inches into the soil
is recorded on the boring logs as "blows per foot ". Blow counts (N values) reported on the boring
logs represent the field blow counts. No corrections have been applied for effects of overburden
pressure, automatic hammer drive energy, drill rod lengths, liners, and sampler diameter.
After logging and sampling the soil, the exploratory borings were backfilled with the excavated
material. The backfill was loosely placed and was not compacted to the requirements specified for
engineered fill.
The subsurface logs are presented on Plates B -1 through B -4 in Appendix B. A key to the log
symbols is presented on Plate B -5. The stratification lines shown on the subsurface logs represent
the approximate boundaries between the various strata. However, the transition from one stratum to
another may be gradual over some range of depth.
Landmark Consultants, Inc. Page 3
Proposed Residential Development — La Quinta, CA LCI Report No. LP05046
2.2 Laboratory Testing
Laboratory tests were conducted on selected bulk and relatively undisturbed soil samples to aid in
classification and evaluation of selected engineering properties of the site soils. The tests were
conducted in general conformance to the procedures of the American Society for Testing and
Materials (ASTM) or other standardized methods as referenced below. The laboratory testing
program consisted of the following tests:
► Particle Size Analyses (ASTM D422) — used for soil classification and liquefaction
evaluation.
► Unit Dry Densities (ASTM D2937) and Moisture Contents (ASTM D2216) — used for
insitu soil parameters.
► Moisture- Density Relationship (ASTM D1557) — used for soil compaction determinations.
► Chemical Analyses (soluble sulfates & chlorides, pH, and resistivity) (Caltrans Methods) —
used for concrete mix evaluations and corrosion protection requirements.
The laboratory test results are presented on the subsurface logs and on Plates C -1 through C -3 in
Appendix C.
Landmark Consultants, Inc. Page 4
Proposed Residential Development — La Quinta, CA LC1 Report No. LP05046
Section 3
DISCUSSION
3.1 Site Conditions
The 5 -acre project site is relatively flat - lying, rectangular in shape, elongated in the north -south
direction and is currently vacant desert land. Thick vegetation, consisting of mesquite, desert
flowers, tall grasses and other large bushes cover the site. A chain -link fence separates the site from
the adjacent properties to the east and west. The site is bounded to the south by Avenue 60, a rural
dirt road.
Adjacent properties are flat -lying and are approximately at the same elevation with this site. A date
palm grove and a single family residential home are located to the west of the site. To the east is a
single family residential community currently under development. Vacant desert land is located
across Avenue 60 to the south. PGA West golf course is located to the north of the site. The All
American Canal, located further west, is approximately 30 feet above the surrounding area.
The project site lies at an elevation of approximately 30 feet below mean sea level (MSL) in the
Coachella Valley region of the California low desert. Annual rainfall in this and region is less than 4
inches per year with four months of average summertime temperatures above 100 °F. Winter
temperatures are mild, seldom reaching freezing.
3.2 Geologic Setting
The project site is located in the Coachella Valley portion of the Salton Trough physiographic
province. The Salton Trough is a geologic structural depression resulting from large scale regional
faulting. The trough is bounded on the northeast by the San Andreas Fault and Chocolate Mountains
and the southwest by the Peninsular Range and faults of the San Jacinto Fault Zone. The Salton
Trough represents the northward extension of the Gulf of California, containing both marine and
non - marine sediments since the Miocene Epoch. Tectonic activity that formed the trough continues
at a high rate as evidenced by deformed young sedimentary deposits and high levels of seismicity.
Figure 1 shows the location of the site in relation to regional faults and physiographic features.
Landmark Consultants, Inc. Page 5
Proposed Residential Development — La Quinta, CA LC1 Report No. LP05046
The surrounding regional geology includes the Peninsular Ranges (Santa Rosa and San Jacinto
Mountains) to the south and west, the Salton Basin to the southeast, and the Transverse Ranges
(Little San Bernardino and Orocopia Mountains) to the north and east. Hundreds of feet to several
thousand feet of Quaternary fluvial, lacustrine, and aeolian soil deposits underlay the Coachella
Valley.
The southeastern part of the Coachella Valley lies below sea level. In the geologic past, the ancient
Lake Cahuilla submerged the area. Calcareous tufa deposits may be observed along the ancient
shoreline as high as elevation 45 to 50 feet MSL along the Santa Rosa Mountains from La Quinta
southward. Lacustrine (lake bed) deposits comprise the subsurface soils over much of the eastern
Coachella Valley with alluvial outwash along the flanks of the valley.
3.3 Seismicity and Faulting
Faulting and Seismic Sources: We have performed a computer -aided search of known faults or
seismic zones that lie within a 62 mile (100 kilometers) radius ofthe project site as shown on Figure
1 and Table 1. The search identifies known faults within this distance and computes deterministic
ground accelerations at the site based on the maximum credible earthquake expected on each of the
faults and the distance from the fault to the site. The Maximum Magnitude Earthquake (Mmax)
listed was taken from published geologic information available for each fault (CDMG OFR 96 -08
and Jennings, 1994).
Seismic Risk: The project site is located in the seismically active Coachella Valley of southern
California and is considered likely to be subjected to moderate to strong ground motion from
earthquakes in the region. The proposed site structures should be designed in accordance with the
California Building Code for near source factors derived from a "Design Basis Earthquake" (DBE).
The DBE is defined as the motion having a 10 percent probability of being exceeded in 50 years.
Seismic Hazards.
► Groundshaking. The primary seismic hazard at the project site is the potential for strong
groundshaking during earthquakes along the San Andreas Fault. A further discussion of
groundshaking follows in Section 3.4.
Landmark Consultants, Inc. Page 6
Proposed Residential Development - La Quinta, Cif LCI Report Nu LP05046
Table 1
FAULT PARAMETERS & DETERMINISTIC
ESTIMATES OF PEAK GRGUNn ACCFI FRATinN 10ce%
Notes.
1. Jennings (1994) and CDMG (1996)
2. CDMG (1996), where Type A faults --slip rate >5 mm /yr and well constrained paleoseismic data
Type B faults -- all other faults.
3. WGCEP (1995)
4. CDMG (1996) based on Wells & Coppersmith (1994)
5. Ellsworth Catalog in USGS PP 1515 (1990) and USBR (1976), Mw = moment magnitude,
6. The deterministic estimates of the Site PGA are based on the attenuation relationship of:
Boore, Joyner, Fumal (1997)
L.ili lull idl-i" l- OnSLI1ia11ts, 111C.
��-Distance
Maximum
Av g
Avg
�-
Date of i Largest
Est
Fault Name or
I (mi) 8
Fault
Fault
Magnitude
Slip
Return
I Last Historic
Site II
Seismic Zone
Direction
I Type
Length
Mmax
Rate
Period
I
i Rupture Event
PGA
from Site
I
km
Mw
(mm/ r )
(yrs )
(year >5.5__M ear
Reference Notes: 1
2
3
2)
(4
F U
L3
3)
, (5)
T (6
San Andreas Fault System
- Coachella Valley
8.9 NE
A
A
i 95
7.4
25
220
1690 + /-
6.5 1948
0.32
- San Gorgonio- Banning
( 12 N
A
I A
98
7.4
10
- --
1 1690 + /-
6.2 1986
0.26
- San Bernardino Mtn
31 NW
A
A
( 107
7.3
24
1 433
1812
6.5 1812
0.12
- Whole S. Calif. Zone
( 8.9 NE
A
345
7.9
- --
- --
1857
7.8 1857
0.41
San Jacinto Fault System
- Hot Spgs -Buck Ridge
13 SSW
B
i A
70
6.5
2
354
6.3 1937
0.16
- Anza Segment
16 SSW
A
A
90
7.2
12
I 250
1918
6.8 1918
0.19
- Coyote Creek
19 SW
B
A
40
6.8
4
175
1968
6.5 1968
0.14
- Borrego Mtn
29 S
B
A
29
I 6.6
4
175
6.5 1942
0.09 I,
- San Jacinto Valley
39 W
B
A
42
6.9
12
83
6.8 1899
0.08
- Elmore Ranch
� 43 ESE
B
A
1 29
6.6
1
225
1987
15.9 1987
0.06
- Superstition Mtn.
46 SSE
B
A
23
6.6
I 5
500
1440+/-
0.06 i
- Superstition Hills
47 SE
B
A
22
6.6
4
250
1987
6.5 1987
0.06
- Whole Zone
18 WSW
I A
i A
245
7.5
--
--
0.20
Mojave Faults
Blue Cut
20 N
B
(C
30
6.8
1
762
0.13 N
Eureka Peak
24 N
C
C
19
6.4
0.6
5,000
' 1992
6.1 1992
i;
; 0.09
Burnt Mtn
24 NNW
B
C
20
6.4
0.6
5,000
1992
7.3 1992
0.09
Morongo
35 NW
C
C
23
6.5
0.6
1,172
5.5 1947
0.07
Pinto Mountain
36 NNW
B I
B
73
7.0
2.5
499
0.09
Bullion Mtn - Mesquite Lk.
37 NNE
B
C
88
7.0
0.6
5,000
I
0.09
S. Emerson - Copper Mtn.
38 N
B
C
54
6.9
0.6
5,000
0.08
Landers
39 NNW
B
C
83
7.3
0.6
5,000
1992
7.3 1992
0.10
N. Johnson Valley
49 NNW
B
C
36
6.7
0.6
5,000 I i
0.06
North Frontal Fault Z. (E)
50 NNW
I
B
C
�
27
6.7
0.5
1,727
I
�
�
0.07
Notes.
1. Jennings (1994) and CDMG (1996)
2. CDMG (1996), where Type A faults --slip rate >5 mm /yr and well constrained paleoseismic data
Type B faults -- all other faults.
3. WGCEP (1995)
4. CDMG (1996) based on Wells & Coppersmith (1994)
5. Ellsworth Catalog in USGS PP 1515 (1990) and USBR (1976), Mw = moment magnitude,
6. The deterministic estimates of the Site PGA are based on the attenuation relationship of:
Boore, Joyner, Fumal (1997)
L.ili lull idl-i" l- OnSLI1ia11ts, 111C.
Proposed Residential Development - La Quinta, CA LCI Repot-t No. LP05046
34.75
34.50
Kmi-i
34.00
33.75
33.50
33.25
Redlands
® M5.5+
® M 5.9 -6.4
oM6.5 -6.9
p M 7.0+
MAP OF REGIONAL FAULTS AND SEISMICITY
\\ \\ Legends to Faults:
BC: Blue Cut
\ \
BM: Borrego Mountain
BSZ: Brawley Seismic Zone
�\
CC: Coyote Creek
CN: Calico- Newberry
EL: Elmore Ranch
ELS: Elsinore
EM -C: Emerson - Copper Mtn.
J EP: Eureka Peak
O S LN\ \ H: H le
� HS -B Hot ot Springs-Buck Ridge
JV: Johnson Valley
F �\ IM:: Imperial
� M: Morongo
ECM -C ML: Mesquite Lake
1 NF: North Frontal Zone
OWS: Old Woman Springs
6.4 ®(92) 7.3 4 (92) P -B: Pisgah - Bullion
I PM Pinto Mtn
�1� SA: San Andreas
SG-B: San Gorgonio- Banning
SH: Superstiition Hills
�K /M�r$%a0 SJ: San J acinto
BC-
Palm SQnngs \,\ RIVERSIDE CO.
La Quinta
Project Site
®(1690)
(69)
Salton
Sea
- 117.25 - 117.00 - 116.75 - 116.50 - 116.25 - 116.00 - 115.75
Copyright 1997 by Shelton L, Stringer, GE
Faults and Seismic Zones from Jennings (1994), Earthquakes modified from Ellsworth (1990) catalog.
Figure 1. Map of Regional Faults and Seismicity
Landmark Consultants, Inc.
Proposed Residential Development — La Quinta, CA LCI Report No. LP05046
► Surface Rupture. The project site does not lie within a State of California, Alquist - Priolo
Earthquake Fault Zone. Surface fault rupture is considered to be unlikely at the project site because
of the well- delineated fault lines through the Coachella Valley as shown on USGS and CDMG maps.
However, because of the high tectonic activity and deep alluvium of the region, we cannot preclude
the potential for surface rupture on undiscovered or new faults that may underlie the site.
► Liquefaction. Liquefaction is unlikely to be a potential hazard at the site since the groundwater is
[believed to be] deeper than 50 feet (the maximum depth that liquefaction is known to occur).
Other Secondary Hazards.
► Landsliding. The hazard of landsliding is unlikely due to the regional planar topography. No
ancient landslides are shown on geologic maps of the region and no indications of landslides were
observed during our site investigation.
► Volcanic hazards. The site is not located in proximity to any known volcanically active area and
the risk of volcanic hazards is considered very low.
► Tsunamis, seiches, and flooding. The site does not lie near any large bodies of water, so the
threat of tsunami, seiches, or other seismically- induced flooding is unlikely. The site is located down
gradient from the All American Canal. If rupture of the canal were to occur due to seismic events,
flooding of the site is possible.
3.4 Site Acceleration and CBC Seismic Coefficients
Site Acceleration: Deterministic horizontal peak ground accelerations (PGA) from maximum
probable earthquakes on regional faults have been estimated and are included in Table 1. Ground
motions are dependent primarily on the earthquake magnitude and distance to the seismogenic
(rupture) zone. Accelerations also are dependent upon attenuation by rock and soil deposits,
direction of rupture and type of fault; therefore, ground motions may vary considerably in the same
general area.
We have used the computer program FRISKSP (Blake, 2000) to provide a probabilistic estimate of
the site PGA using the attenuation relationship of Boore, Joyner, and Fumal (1997) Soil (310). The
PGA estimate for the project site having a 10% probability of occurrence in 50 years (return period
of 475 years) is 0.55g.
Landmark Consultants, Inc. Page 7
Proposed Residential Development — La Quinta, CA LC1 Report No. LP05046
CBC Seismic Coefficients: The CBC seismic coefficients are roughly based on an earthquake
ground motion that has a 10% probability of occurrence in 50 years. The following table lists
seismic and site coefficients (near source factors) determined by Chapter 16 of the 2001 California
Building Code (CBC). This site lies within 14.3 km of a Type A fault overlying So (stiff soil.
CBC Seismic Coefficients for Chapter 16 Seismic Provisions
3.5 Subsurface Soil
Subsurface soils encountered during the field exploration conducted on February 28, 2005 consist of
loose to medium dense interbedded sandy silts and silty sands. The subsurface logs (Plates B -1
through B -4) depict the stratigraphic relationships of the various soil types.
3.6 Groundwater
Groundwater was not encountered in the borings during the time of exploration, and is believed to be
deeper than 50 feet below ground surface at this site. There is uncertainty in the accuracy of short-
term water level measurements, particularly in fine- grained soil. Groundwater levels may fluctuate
with precipitation, irrigation of adjacent properties, drainage, and site grading. The groundwater
level noted should not be interpreted to represent an accurate or permanent condition.
Landmark Consultants, Inc. page 8
Seismic
Distance to
Near Source Factors
Seismic Coefficients
CBC Code
Soil Profile
Edition
Type
Source
Critical
Type
Source
Na
Nv
Ca
Cv
2001
S.
(stiff soil)
A
< 14.3 km
1.00
1.03
0.44
0.66
Ref. Table
16 -J
16 -U
- --
16 -5
16 -T
16 -Q
16 -R
3.5 Subsurface Soil
Subsurface soils encountered during the field exploration conducted on February 28, 2005 consist of
loose to medium dense interbedded sandy silts and silty sands. The subsurface logs (Plates B -1
through B -4) depict the stratigraphic relationships of the various soil types.
3.6 Groundwater
Groundwater was not encountered in the borings during the time of exploration, and is believed to be
deeper than 50 feet below ground surface at this site. There is uncertainty in the accuracy of short-
term water level measurements, particularly in fine- grained soil. Groundwater levels may fluctuate
with precipitation, irrigation of adjacent properties, drainage, and site grading. The groundwater
level noted should not be interpreted to represent an accurate or permanent condition.
Landmark Consultants, Inc. page 8
Proposed Residential Development — La Quinta, CA LCl Report No. LP05046
Section 4
RECOMMENDATIONS
4.1 Site Preparation
Clearing and Grubbing All surface improvements, debris or vegetation including grass, trees, and
weeds on the site at the time of construction should be removed from the construction area. Root
balls should be completely excavated. Organic strippings should be hauled from the site and not
used as fill. Any trash, construction debris, concrete slabs, old pavement, landfill, and buried
obstructions such as old foundations and utility lines exposed during rough grading should be traced
to the limits of the foreign material by the grading contractor and removed under our supervision.
Any excavations resulting from site clearing should be dish - shaped to the lowest depth of
disturbance and backfilled under the observation of the geotechnical engineer's representative.
Building Pad Preparation: The existing surface soil within the building pad areas should be removed
to 36 inches below the existing grade or 18 inches below the lowest foundation grade (whichever is
lower) extending five feet beyond all exterior wall /column lines (including adjacent concreted areas).
Exposed subgrade should be scarified to a depth of 12 inches, uniformly moisture conditioned to
optimum moisture f 2% and recompacted to a minimum of 90% of the maximum density
determined in accordance with ASTM D 1557 Methods.
The native soil is suitable for use as engineered fill provided it is free from concentrations of organic
matter or other deleterious material. The fill soil should be uniformly moisture conditioned by
discing and watering to the limits specified above, placed in maximum 8 -inch lifts (loose), and
compacted to the limits specified above.
Imported fill soil (if required) should be similar to onsite soil or non - expansive, granular soil meeting
the USCS classifications of SM, SP -SM, or SW -SM with a maximum rock size of 3 inches. The
geotechnical engineer should approve imported fill soil sources before hauling material to the site.
Imported granular fill should be placed in lifts no greater than 8 inches in loose thickness and
compacted to a minimum of 90% of ASTM D 1557 maximum dry density at optimum moisture ±2 %.
In areas other than the building pad which are to receive area concrete slabs, the ground surface
should be scarified to 12 inches, moisture conditioned to at optimum moisture ±2% and recompacted
to a minimum of 90% of ASTM D 15 57 maximum density just prior to concrete placement.
Landmark Consultants, Inc. Page 9
Proposed Residential Development — La Quinta, CA LCI Report No. LP05046
Trench Backfill: On -site soil free of debris, vegetation, and other deleterious matter may be suitable
for use as utility trench backfill. Backfill soil within roadways should be placed in layers not more
than 6 inches in thickness and mechanically compacted to a minimum of 90% of the ASTM D 1557
maximum dry density except for the top 12 inches of the trench which shall be compacted to at least
90 %. Native backfill should only be placed and compacted after encapsulating buried pipes with
suitable bedding and pipe envelope material. Pipe envelope /bedding should either be clean sand
(Sand Equivalent SE >30) or crushed rock when encountering groundwater. A geotextile filter fabric
(Mirafi 140N or equivalent) should be used to encapsulate the crushed rock to reduce the potential
for in- washing of fines into the gravel void space. Precautions should be taken in the compaction of
the backfill to avoid damage to the pipes and structures.
Moisture Control and Drainage: The moisture condition of the building pad should be maintained
during trenching and utility installation until concrete is placed or should be rewetted before
initiating delayed construction.
Adequate site drainage is essential to future performance of the project. Infiltration of excess
irrigation water and storm waters can adversely affect the performance of the subsurface soil at the
site. Positive drainage should be maintained away from all structures (5% for 5 feet minimum across
unpaved areas) to prevent ponding and subsequent saturation of the native clay soil. Gutters and
downspouts may be considered as a means to convey water away from foundations. If landscape
irrigation is allowed next to the building, drip irrigation systems or lined planter boxes should be
used. The subgrade soil should be maintained in a moist, but not saturated state, and not allowed to
dry out. Drainage should be maintained without ponding.
Observation and Density Testing_ All site preparation and fill placement should be continuously
observed and tested by a representative of a qualified geotechnical engineering firm. Full -time
observation services during the excavation and scarification process is necessary to detect
undesirable materials or conditions and soft areas that may be encountered in the construction area.
The geotechnical firm that provides observation and testing during construction shall assume the
responsibility of " geotechnical engineer of record' and, as such, shall perform additional tests and
investigation as necessary to satisfy themselves as to the site conditions and the recommendations for
site development.
Landmark Consultants, Inc. Page 10
Proposed Residential Development — La Quinta, CA LCL Report No. LP05046
Auxiliary Structures Foundation Preparation: Auxiliary structures such as free standing or retaining
walls should have the existing soil beneath the structure foundation prepared in the manner
recommended for the building pad except the preparation needed only to extend 18 inches below and
beyond the footing.
4.2 Foundations and Settlements
Shallow spread footings and continuous wall footings are suitable to support the structures provided
they are structurally tied with grade -beams to resist differential movement. Footings shall be
founded on a layer of properly prepared and compacted ,soil as described in Section 4.1. The
foundations may be designed using an allowable soil bearing pressure of 1,500 psf. The allowable
soil pressure may be increased by 20% for each foot of embedment depth in excess of 18 inches and
by one -third for short term loads induced by winds or seismic events. The maximum allowable soil
pressure at increased embedment depths shall not exceed 2,500 psf.
All exterior and interior foundations should be embedded a minimum of 18 inches below the
building support pad or lowest adjacent final grade, whichever is deeper. Interior footings may be 12
inches deep. Continuous wall footings should have a minimum width of 12 inches. Spread footings
should have a minimum dimension of 24 inches. Recommended concrete reinforcement and sizing
for all footings should be provided by the structural engineer.
Resistance to horizontal loads will be developed by passive earth pressure on the sides of footings
and frictional resistance developed along the bases of footings and concrete slabs. Passive resistance
to lateral earth pressure may be calculated using an equivalent fluid pressure of 300 pcf for sands to
resist lateral loadings. The top one foot of embedment should not be considered in computing
passive resistance unless the adjacent area is confined by a slab or pavement. An allowable friction
coefficient of 0.35 for sands may also be used at the base of the footings to resist lateral loading.
Foundation movement under the estimated static (non- seismic) loadings and static site conditions are
estimated to not exceed' /4 inch with differential movement of about two- thirds of total movement for
the loading assumptions stated above when the subgrade preparation guidelines given above are
followed.
Landmark Consultants, Inc. Page I 1
Proposed Residential Development — La Quinta, CA LCI Report No. LP05046
4.3 Slabs -On -Grade
Concrete slabs and flatwork should be a minimum of 4 inches thick. Concrete floor slabs may either
be monolithically placed with the foundation or dowelled after footing placement. The concrete
slabs may be placed on granular subgrade that has been compacted at least 90% relative compaction
(ASTM D1557) and moistened to near optimum moisture just before the concrete placement
To provide protection against vapor or water transmission through the slabs, we recommend that the
slabs -on -grade be underlain by a layer of clean concrete sand at least 4 inches thick. To provide
additional protection against water vapor transmission through the slab in areas where vinyl or other
moisture - sensitive floor covering is planned, we recommend that a 10 -mil thick impermeable plastic
membrane (visqueen) be placed at mid - height within the sand layer. The vapor inhibitor should be
installed in accordance with the manufacturer's instructions. We recommend that at least a 2 -foot
lap be provided at the membrane edges or that the edges be sealed.
Concrete slab and flatwork reinforcement should consist of chaired rebar slab reinforcement
(minimum of No. 3 bars at 18 -inch centers, both horizontal directions) placed at slab mid - height to
resist potential swell forces and cracking. Slab thickness and steel reinforcement are minimums only
and should be verified by the structural engineer /designer knowing the actual project loadings. All
steel components of the foundation system should be protected from corrosion by maintaining a 3-
inch minimum concrete cover of densely consolidated concrete at footings (by use of a vibrator).
The construction joint between the foundation and any mowstrips /sidewalks placed adjacent to
foundations should be sealed with a polyurethane based non - hardening sealant to prevent moisture
migration between the joint. Epoxy coated embedded steel components or permanent waterproofing
membranes placed at the exterior footing sidewall may also be used to mitigate the corrosion
potential of concrete placed in contact with native soil.
Control joints should be provided in all concrete slabs -on -grade at a maximum spacing (in feet) of 2
to 3 times the slab thickness (in inches) as recommended by American Concrete Institute (ACI)
guidelines. All joints should form approximately square patterns to reduce randomly oriented
contraction cracks. Contraction joints in the slabs should be tooled at the time of the pour or sawcut
('/4 of slab depth) within 6 to 8 hours of concrete placement. Construction (cold) joints in
foundations and area flatwork should either be thickened butt joints with dowels or a thickened
keyed joint designed to resist vertical deflection at the joint. All joints in flatwork should be sealed
Landmark Consultants, Inc. Page 12
Proposed Residential Development — La Quinta, CA LCl Report No LP05046
to prevent moisture, vermin, or foreign material intrusion. Precautions should be taken to prevent
curling of slabs in this arid desert region (refer to ACI guidelines).
All independent flatwork (sidewalks, patios) should be placed on a minimum of 2 inches of concrete
sand or aggregate base, dowelled to the perimeter foundations where adjacent to the building and
sloped 2% or more away from the building. A minimum of 24 inches of moisture conditioned (5%
minimum above optimum) and 8 inches of compacted subgrade (83 to 87 %) and a 10 -mil
(minimum) polyethylene separation sheet should underlie the flatwork containing steel reinforcing
(except wire mesh). All flatwork should be jointed in square patterns and at irregularities in shape at
a maximum spacing of 10 feet or the least width of the sidewalk. Driveway slabs should have a
thickened edge extending a minimum of 4 inches below a 4 -inch sand or aggregate base course
which should be compacted to a minimum of 90% of ASTM D 1557 maximum density.
4.4 Concrete Mixes and Corrosivity
Selected chemical analyses for corrosivity were conducted on bulk samples of the near surface soil
from the project site (Plate C -3). The native soils have low levels of sulfate ion concentration (78-
743 ppm). Sulfate ions in high concentrations can attack the cementitious material in concrete,
causing weakening of the cement matrix and eventual deterioration by raveling.
A minimum of 2,500 psi concrete of Type Il Portland Cement with a maximum water /cement ratio
of 0.60 (by weight) should be used for concrete placed in contact with native soil on this project
(sitework including streets, sidewalks, driveways, patios, and foundations).
The native soil has low to severe level of chloride ion concentration (70 -1,190 ppm). Chloride ions
can cause corrosion of reinforcing steel, anchor bolts and other buried metallic conduits. Resistivity
determinations on the soil indicate low to very severe potential for metal loss because of
electrochemical corrosion processes. Mitigation of the corrosion of steel can be achieved by using
steel pipes coated with epoxy corrosion inhibitors, asphaltic and epoxy coatings, cathodic protection
or by encapsulating the portion of the pipe lying above groundwater with a minimum of 3 inches of
densely consolidated concrete. No metallic pipes or conduits should be placed belowfoundations.
Landmark Consultants, Inc. Page 13
Proposed Residential Development — La Quinta, CA LCI Report No. LP05046
Foundation designs shall provide a minimum concrete cover of three (3) inches around steel
reinforcing or embedded components (anchor bolts, hold - downs, etc.) exposed to native soil or
landscape water (to 18 inches above grade). If the 3 -inch concrete edge distance cannot be achieved,
all embedded steel components (anchor bolts, hold- downs, etc.) shall be epoxy dipped for corrosion
protection or a corrosion inhibitor and a permanent waterproofing membrane shall be placed along
the exterior face of the exterior footings. Additionally, the concrete should be thoroughly vibrated at
footings during placement to decrease the permeability of the concrete.
4.5 Excavations
All site excavations should conform to CalOSHA requirements for Type B soil. The contractor is
solely responsible for the safety of workers entering trenches. Temporary excavations with depths of
4 feet or less may be cut nearly vertical for short duration. Sandy soil slopes should be kept moist,
but not saturated, to reduce the potential of raveling or sloughing. Excavations deeper than 4 feet
will require shoring or slope inclinations in conformance to CAUOSHA regulations for Type B soil.
Surcharge loads of stockpiled soil or construction materials should be set back from the top of the
slope a minimum distance equal to the height of the slope. All permanent "slopes should not be
steeper than 3:1 to reduce wind and rain erosion. Protected slopes with ground cover may be as steep
as 2:1. However, maintenance with motorized equipment may not be possible at this inclination.
4.6 Lateral Earth Pressures
Earth retaining structures, such as retaining walls, should be designed to resist the soil pressure
imposed by the retained soil mass. Walls with granular drained backfill may be designed for an
assumed static earth pressure equivalent to that exerted by a fluid weighing 35 pcf for unrestrained
(active) conditions (able to rotate 0.1% of wall height), and 55 pcf for restrained (at -rest) conditions.
These values should be verified at the actual wall locations during construction.
When applicable seismic earth pressure on walls may be assumed to exert a uniform pressure
distribution of 7.5H psf against.the back of the wall, where H is the height of the backfill. The total
seismic load is assumed to act as a point load at 0.6H above the base of the wall.
Landmark Consultants, Inc. Page 14
Proposed Residential Development — La Quinta, CA LC1 Report No. LP05046
Surcharge loads should be considered if loads are applied within a zone between the face of the wall
and a plane projected behind the wall 45 degrees upward from the base of the wall. The increase in
lateral earth pressure acting uniformly against the back of the wall should be taken as 50% of the
surcharge load within this zone. Areas of the retaining wall subjected to traffic loads should be
designed for a uniform surcharge load equivalent to two feet of native soil.
Walls should be provided with backdrains to reduce the potential for the buildup of hydrostatic
pressure. The drainage system should consist of a composite HDPE drainage panel or a 2 -foot wide
zone of free draining crushed rock placed adjacent to the wall and extending 2/3 the height of the
wall. The gravel should be completely enclosed in an approved filter fabric to separate the gravel
and backfill soil. A perforated pipe should be placed perforations down at the base of the permeable
material at least six inches below finished floor elevations. The pipe should be sloped to drain to an
appropriate outlet that is protected against erosion. Walls should be properly waterproofed. The
project geotechnical engineer should approve any alternative drain system.
4.7 Seismic Design
This site is located in the seismically active southern California area and the site structures are
subject to strong ground shaking due to potential fault movements along the San Andreas Fault.
Engineered design and earthquake- resistant construction are the common solutions to increase safety
and development of seismic areas. Designs should comply with the latest edition of the CBC for
Seismic Zone 4 using the seismic coefficients given in Section 3.4 of this report. This site lies
within 14.3 km of a Type A fault overlying So (stifn soil.
4.8 Pavements
Pavements should be designed according to CALTRANS or other acceptable methods. Traffic
indices were not provided by the project engineer or owner; therefore, we have provided structural
sections for several traffic indices for comparative evaluation. The public agency or design engineer
should decide the appropriate traffic index for the site. Maintenance of proper drainage is necessary
to prolong the service life of the pavements. Based on the current State of California CALTRANS
method, an estimated R -value of 40 for the subgrade soil and assumed traffic indices, the following
table provides our estimates for asphaltic concrete (AC) pavement sections.
Landmark Consultants, Inc. Page 15
Proposed Residential Development — La Quinta, CA LCI Report No LP05046
RECOMMENDED PAVEMENTS SECTIONS
R -Value of Subgrade Soil - 40 (estimated) Desiun Merhnrl - C AI TR AMC i Goo
Traffic
Flexible Pavements
Asphaltic
Aggregate
Index
Concrete
Base
(assumed)
Thickness
Thickness
(in.)
(in.)
5.0
3.0
4.5
6.0
3.5
6.0
7.0
4.5
6.5
8.0
5.0
8.5
Notes:
1) Asphaltic concrete shall be Caltrans, Type B,' /4 inch maximum medium grading, (%2 inch for
parking areas) compacted to a minimum of 95% of the 50 -blow Marshall density (ASTM
D1559).
2) Aggregate base shall conform to Caltrans Class 2 ('/4 in. maximum), compacted to a
minimum of 95% of ASTM D 1557 maximum dry density.
3) Place pavements on 8 inches of moisture conditioned (minimum 4% above optimum) native
soil compacted to a minimum of 90% of the maximum dry density determined by ASTM
D1557.
Final recommended section may need to be based on sampling and R -Value testing during grading
operations when actual subgrade soils will be exposed.
Landmark Consultants, Inc. Page 16
Proposed Residential Development — La Quinta, CA LC1 Report No. LP05046
Section 5
LIMITATIONS AND ADDITIONAL SERVICES
5.1 Limitations
The recommendations and conclusions within this report are based on current information regarding
the proposed residential development located near the northwest corner of Avenue 60 and Madison
Street south of La Quinta, California. The conclusions and recommendations of this report are
invalid if:
► Structural loads change from those stated or the structures are relocated.
The Additional Services section of this report is not followed.
► This report is used for adjacent or other property.
► Changes of grade or groundwater occur between the issuance of this report and
construction other than those anticipated in this report.
► Any other change that materially alters the project from that proposed at the time this
report was prepared.
Findings and recommendations in this report are based on selected points of field exploration,
geologic literature, laboratory testing, and our understanding of the proposed project. Our analysis of
data and recommendations presented herein are based on the assumption that soil conditions do not
vary significantly from those found at specific exploratory locations. Variations in soil conditions
can exist between and beyond the exploration points or groundwater elevations may change. If
detected, these conditions may require additional studies, consultation, and possible design revisions.
This report contains information that may be useful in the preparation of contract specifications.
However, the report is not worded is such a manner that we recommend its use as a construction
specification document without proper modification. The use of information contained in this
report for bidding purposes should be done at the contractor's option and risk.
This report was prepared according to the generally accepted geotechnical engineering standards of
practice that existed in Riverside County at the time the report was prepared. No express or implied
warranties are made in connection with our services. This report should be considered invalid for
periods after two years from the report date without a review of the validity of the findings and
recommendations by our firm, because of potential changes in the Geotechnical Engineering
Standards of Practice.
Landmark Consultants, Inc. Page 17
Proposed Residential Development — La Quinta, CA LCl Report No. LP05046
The client has responsibility to see that all parties to the project including, designer, contractor, and
subcontractor are made aware of this entire report. The use of information contained in this report
for bidding purposes should be done at the contractor's option and risk.
5.2 Additional Services
We recommend that Landmark Consultants, Inc. be retained as the geotechnical consultant to
provide the tests and observations services during construction. If Landmark Consultants does not
provide such services then the geotechnical engineering firm providing such tests and observations
shall become the geotechnical engineer of record and assume responsibility for the project.
The recommendations presented in this report are based on the assumption that:
► Consultation during development of design and construction documents to check that the
geotechnical recommendations are appropriate for the proposed project and that the
geotechnical recommendations are properly interpreted and incorporated into the
documents.
► Landmark Consultants will have the opportunity to review and comment on the plans and
specifications for the project prior to the issuance of such for bidding.
► Continuous observation, inspection, and testing by the geotechnical consultant of record
during site clearing, grading, excavation, placement of fills, building pad and subgrade
preparation, and backfilling of utility trenches.
► Observation of foundation excavations and reinforcing steel before concrete placement.
► Other consultation as necessary during design and construction.
We emphasize our review of the project plans and specifications to check for compatibility with our
recommendations and conclusions. Additional information concerning the scope and cost of these
services can be obtained from our office.
Landmark Consultants, Inc. Page 18
Legend
Approximate Boring Location (typ)
LANDMARK
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CLIENT: Mr. Sevak Kachadurian METHOD OF DRILLING: CME 55 w /autohammer
PROJECT: Proposed Residential Development - La Ouinta, CA DATE OBSERVED: 02/28/05
LOCATION: See Site and Exploration Plan LOGGED BY: TB
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Project No:
LANDMARK
Plate
LP05046
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SIEVE ANALYSIS HYDROMETER ANALYSIS
Gravel ==
Sand Silt and Clay Fraction
Coarse Fine
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90
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1 0.1 0.01 0.001
Particle Size (mm)
LANDMARK
Geo-Engineers and Geologists
a DBEIMBEISBE Company
Plate
Project No.: LP05046
Grain Size Analysis
C-1
145
140
135
c3 120
115
110
105
Moisture Content (%)
LANDMARK
Geo-Engineers and Geologists
Project No: LP05046 Moisture Density Relationship C-2
Client: Mr. Sevak Kachadurian
Project: Proposed Residential Development
Project No: LP05046
Date: 03/24/05
SUMMARY OF TEST RESULTS
Description: Silty Sand (SM)
Test Method: ASTM D1557A
Maximum Dry
Density (pc�: 117.0
Optimum Moisture
Content 10.0
Moisture Content (%)
LANDMARK
Geo-Engineers and Geologists
Project No: LP05046 Moisture Density Relationship C-2
LANDMARK CONSULTANTS, INC.
CLIENT: Mr. Sevak Kachadurian
PROJECT: Proposed Residential Development - La Quinta, CA
JOB NO: LP05046
DATE: 03/25/05
CHEMICAL ANALYSES
Boring:
B -1
B -4
CalTrans
Sample Depth, ft:
0 -5
0 -5
Method
pH:
6.39
6.70
643
Resistivity (ohm -cm):
270
9,500
643
Chloride (Cl), ppm:
1,190
70
422
Sulfate (SO4), ppm:
743
78
417
General Guidelines for Soil Corros
Material
Chemical
Amount in
Degree of
Affected
_ Agent
Soil (ppm)
Corrosivity
Concrete
Soluble
0-1000
Low
Sulfates
1000-2000
Moderate
2000-20000
Severe
> 20000
Very Severe
Normal
Soluble
0-200
Low
Grade
Chlorides
200-700
Moderate
Steel
700-1500
Severe
> 1500
Very Severe
Normal
Resistivity
1 -1000
Very Severe
Grade
1000 -2000
Severe
Steel
2000 - 10,000
Moderate
10,000+
Low
LANDMARK
Geo-Engineers and Geologists
a DBE /MBE /SSE Compan y
Project No: LP05046
Selected Chemical
Analyses Results
Plate
C -3
REFERENCES
Arango I., 1996, Magnitude Scaling Factors for Soil Liquefaction Evaluations: ASCE
Geotechnical Journal, Vol. 122, No. 11.
Bartlett, Steven F. and Youd, T. Leslie, 1995, Empirical Prediction of Liquefaction -
Induced Lateral Spread: ASCE Geotechnical Journal, Vol. 121, No. 4.
Blake, T. F., 1989 -1996, FRISKSP - A computer program for the probabilistic estimation
of seismic hazard using faults as earthquake sources.
Bolt, B. A., 1974, Duration of Strong Motion: Proceedings 5th World Conference on
Earthquake Engineering, Rome, Italy, June 1974.
Boore, D. M., Joyner, W. B., and Fumal, T. E., 1994, Estimation.of response spectra and
peak accelerations from western North American earthquakes: U.S. Geological
Survey Open File Reports 94 -127 and 93 -509.
Building Seismic Safety Council (BSSC), 1991, NEHRP recommended provisions for the
development of seismic regulations of new buildings, Parts 1, 2 and Maps:
FEMA 222, January 1992
California Division of Mines and Geology (CDMG), 1996, California Fault Parameters:
available at http: / /www.consrv.ca.gov /dmg/shezp /fltindex.html.
Ellsworth, W. L., 1990, Earthquake History, 1769 -1989 in: The San Andreas Fault
System, California: U.S. Geological Survey Professional Paper 1515, 283 p.
International Conference of Building Officials (ICBO), 1994, Uniform Building Code,
1994 Edition.
International Conference of Building Officials (ICBO), 1997, Uniform Building Code,
1997 Edition.
Jennings, C. W., 1994, Fault activity map of California and Adjacent Areas: California
Division of Mines and Geology, DMG Geologic Map No. 6.
Jones, L. and Hauksson, E., 1994, Review of potential earthquake sources in Southern
California: ' Applied Technology Council, Proceedings of ATC 35 -1.
Joyner, W. B. and Boore, D. M., 1988, Measurements, characterization, and prediction of
strong ground motion: ASCE Geotechdical Special Pub. No. 20.
Mualchin, L. and Jones, A. L., 1992, Peak acceleration from maximum credible
earthquakes in California (Rock and Stiff Soil Sites): California Division of
Mines and Geology, DMG Open File Report 92 -01.
Naeim, F. and Anderson, J. C., 1993, Classification and evaluation of earthquake records
for design: Earthquake Engineering Research Institute, NEHRP Report.
National Research Council, Committee of Earthquake Engineering, 1985, Liquefaction of
Soils during Earthquakes: National Academy Press, Washington, D.C.
Porcella, R. L., Matthiesen, R.. B., and Maley, R. P., 1982, Strong- motion data recorded
in the United States: U.S. Geological Survey Professional Paper 1254, p. 289-
318.
Robertson, P. K., 1996, Soil Liquefaction and its evaluation based on SPT and CPT: in
unpublished paper presented at 1996 NCEER Liquefaction Workshop
Seed, Harry B., Idriss, I. M., and Arango I., 1983, Evaluation of liquefaction potential
using field performance data: ASCE Geotechnical Journal, Vol. 109, No. 3.
Seed, Harry B., et al, 1985, Influence of SPT Procedures in Soil Liquefaction Resistance
Evaluations: ASCE Geotechnical Journal, Vol. 113, No. 8.
Sharp, R. V., 1989, Personal communication, USGS; Menlo Park, CA.
Stringer, S. L., 1996, EQFAULT.WK4, A computer .program for the estimation of
deterministic site acceleration.
Stringer, S. L. 1996, LIQUEFY.WK4, A computer program for the Empirical Prediction
of Earthquake - Induced Liquefaction Potential.
Structural Engineers Association of California (SEAOC), 1990, Recommended lateral
force requirements and commentary.
Tokimatsu, K. and Seed H. B., 1987, Evaluation of settlements in sands due to
earthquake shaking: ASCE Geotechnical Journal, v. 113, no. 8.
U.S. Geological Survey (USGS), 1990, The San Andreas Fault System, California,
Professional Paper 1515.
U.S. Geological Survey (USGS), 1996, National Seismic Hazard Maps: available at
http://gldage.-cr.usgs.gov
Wallace, R. E., 1990,. The San Andreas Fault System, California: U.S. Geological
Survey Professional Paper 1515, 283 p.
Working Group on California Earthquake Probabilities (WGCEP), 1988, Probabilities of
large earthquakes occurring in California on the San Andreas Fault: U.S.
Geological Survey Open -File Report 88 -398.
Working Group on California Earthquake Probabilities (WGCEP), 1992, Future seismic
hazards in southern California, Phase I Report: California Division of Mines and
Geology.
Working Group on California Earthquake Probabilities (WGCEP), 1995, Seismic hazards
in southern California, Probable Earthquakes, 1994 -2014, Phase II Report:
Southern California Earthquake Center.
Youd, T. Leslie and Garris, C. T., 1995, Liquefaction induced ground surface disruption:
AS CE Geotechnical Journal, Vol. 121, No. 11.
•>
1
PRELIMINARY
HYDROLOGY AND
HYDRAULICS REPORT
for
Amended
Tract 32848
City of La Quinta
r•
July 23, 2007
RECEIVED
AUG 13 2007
Prepared for:
Sevak Khatchadourian Development Services
137 South Reeves Dr., Suite 303
Beverly Hills, Ca 90212
Phone: (310) 560 -1688
Fax: (310) 858 -1397
Prepared by:
Terra Solutions, Inc.
2280 Market St., Ste 220
Riverside, CA 92501
Phone: (951) 328 -0400
Fax: (951) 328 -0401
Prepared under the supervision of:
Juan Manuel Sanchez, P.E. RCE 30846 Exp. 03 -31 -08
No. 30849
EV: 3 -31-06
;r -�, 'f,
.f' `; �i
1''. �• ''
Introduction
Purpose
Methodology
Findings
Summary
Subsequent Hydrology
Hydrology Exhibits
Table of Contents
Exhibit No. 1: Flows for pre - developed condition
Exhibit No. 2: Flows for developed condition after level of water reaches the
spillway.
Exhibit No. 3: Sections A A and B -B.
Exhibit 4A: Drainage Map City. of La Quinta
Exhibit S: 1,000 year storm factors.
In -Tract Hydrology and Hydraulic Calculations
A.- 100 and 10 Year Rational Method AMC II, Developed Condition
B.- W.S.P. G. W. for pipe .
C.- Street capacity calculation
D.- Catch basin calculations
E.- Unit Hydrograph shortcut method: 100 year storm, 3 hour duration.
In tract
Off site
F.- Retention basins calculation
In tract
Off site
G.- -Hydrology Map
In tract
Off site
0
• Introduction
Amended Tentative Tract Map 32848 is a 5.2 -acre subdivision, consisting of 15 ten
thousand square foot lots, located on the north side of Avenue 60, west of Madison
Street, in the City of La Quinta,. County of Riverside, California. An ultimate master plan
storm drain system does not exist downstream or adjacent to the property, therefore the
proposed storm drain system for the subdivision will convey the majority of the on -site
storm water runoff to a proposed retention basin at the north (lowest) end of the
subdivision. This retention basin will be designed to hold at least the 100 year storm.
A smaller retention basin at the south -east corner of the subdivision, will pick up the off
site flows from the adjacent street (Avenue 60). This retention basin will hold at least the
100 year off -site storm event. Off -site meaning that portion of Avenue.60 adjacent to the
subdivision, the 20 feet wide landscape area and the basin itself.
Therefore the retention basins will hold at least 100% of the 100 -year storm runoff at the
developed condition.
The existing drainage pattern of the site sheet flows to the north -east, (see Exhibit No. 1).
After the retention basins are in place, there will be no flows during-the 100 year storm
onto the property to the north, (see exhibit No. 3, section A -A).
In the case of a more severe storm (greater than 100 -year storm) the basin will have
additional capacity to hold up to the 1,000 year storm and will also comply with the City
of La Quinta requirement of one foot of freeboard. After the spillway elevation (462.5) at
• S the major retention basin is reached, the spillway will direct the flows to the northerly
property as a sheet flow, similar to the presently existing condition; (see Exhibit No. 2). It
is necessary to reiterate that in the 100 -year event, no flows will spill over onto the
property to the north.
The same design concept was used for the smaller retention basin located at the southeast
portion of the subdivision, adjacent to Avenue 60. This retention basin is designed to hold
at least the 100 -year storm runoff produced by the off -site portion of Tract No. 32848.
Also in case of severe storm the basin has the capacity to hold up to 1,000 year storm
event. A modified curb drain will be installed in front of the basin on Avenue 60 to
collect the offsite flows and direct them into the basin. After the spillway elevation is.
reached (474.74), an overflow swale will convey the storm water runoff back to Avenue
60. Under normal conditions of functioning the retention basin will hold the at least 100 -
year storm runoff, (see Exhibit No. 3 section B -B).
Purpose
The purpose of this Preliminary Hydrology Report is to determine storm water runoff for
the site. It is also to show that drainage systems, comprised of proposed streets, catch
basins, storm drain pipelines and retention basins are adequately sized. Hydraulic .
calculations for the storm drain systems and catch basins are included in this report along
with the hydrology exhibits.
According to the City of La Quinta Engineering Bulletin #06 -16 for Retention basin
design, the Synthetic Unit Hydrograph Analysis (short cut method) should be used for .
projects smaller than 100 acres and lag time lower than 7 minutes. The retention basin(s)
shall be designed to hold the 1.00 year, 3 hour duration storm.
Methodolo
The rational method, as outlined by the current Riverside County Flood Control
Hydrology Manual, is used to determine the 100 -year and 10 -year event storm water
runoff (Q).
Retention basins are designed to hold the 100 year, 3 hour duration storm.
Calculations are performed using the short cut synthetic hydrograph method from the
Riverside County Flood Control Hydrology Manual.
One foot of freeboard is built into the retention basin, as required by the City Engineering
Bulletin for Hydrology, in order to minimize the potential of flooding onto the properties
downstream and in this case northerly of the subdivision.
Please note that no infiltration was considered at the floor of the retention basin(s).
Recommended values for infiltration rates will. be used in the final Hydrology Report
after percolation testing is performed at the site, prior to Final Engineering.
Computer programs such as Civi1D, AES and W.S.P.G.W. are utilized herein. .
Findings
IN -TRACT — The proposed interior tract street adequately conveys the 100 -year and 10-
year storm run -off, towards the proposed in tract retention basin.
A Storm drain pipeline system will be constructed with one catch basin at the north end
of the cul -de -sac to convey the in -tract flows to the retention basin at the north end. A 24
inches RCP will be used to convey the water from the catch basin to the retention basin
W.S.P.G.W. is provided for the 24" pipe.
Street capacity calculations are provided for the 10 years storm event.
OFF -SITE — The existing Avenue 60 will convey the off -site flows to the small retention
basin located on the north -east corner of the tract though a modified curb inlet.
Summary -
The on -site street (cul -de -sac) and storm drain system proposed for the subdivision will
adequately convey the 100 year and 10 year event storm water runoff to the proposed
retention basin.
The volume necessary for the on -site retention basin without infiltration for the 100 year,
3 hour duration storm is calculated to be 0.73 Ac -ft (31,583 cf).
The volume needed for the off -site retention basin without infiltration for the 100 year, 3
hour duration storm is calculated to be 0.09 Ac -ft (3,814 cf).
The two basins in this case will be designed to hold 100% of the 1,000 year storm as a
factor of safety beyond the recommended 100 year storm. In order to obtain the values
for 1,000 year storm the 100 year storm values have been multiplied by 1.45. See
Riverside County Flood Control and Water Conservation District Hydrology Manual,
' page B -2 on Exhibit No. 5
In tract retention basin.(At the northerly property line)
Elevation for the bottom of the retention basin = 457.00 ft
Elevation of the spillway = 462.50 ft
Elevation of the 100 year storm = 460.14 ft
Elevation of 1,000 year storm = 461.20 ft
Freeboard for 1,000 year+ 1.30 ft
Storm event
Maximum water elevation
Volume
year
ft
cu -ft
100
460:14
32,029
1,000
461.20
47,817
up to spillway
462.50
69,836
VOLUME REQUIRED 100 YEAR STORM = 31,583 CF
VOLUME REQUIRED 1,000 YEAR STORM = 45,795 CF
Off site retention basin (At Avenue 60)
Elevation for the bottom of the retention basin = 472.50 ft
Elevation of the spillway 474.74 ft
Elevation of the 100 year storm = 473.38 ft
Elevation of 1,000 year storm = 473.74 ft
Freeboard for 1,000 year= 1.35 ft
Freeboard
ft
2.36
1.30
0.00
Storm event
Maximum water elevation
Volume
Freeboard
year
ft .
cu -ft
ft
100
473.38
3,932
1.36
1,000
473.74
5,752
1.00
up to. spillway
474.74
11,026
0.00
•) VOLUME REQUIRED 100 YEAR STORM = 3,81.4 CF
VOLUME REQUIRED 15000 YEAR STORM= 5,530 CF
Subsequent hydrology
This hydrology and hydraulic report is preliminary in nature for locating and sizing the
retention and should be taken as such. It will be followed by a subsequent report(s) as the
preliminary grading is updated and changed and as final design moves forward. The final
Hydrology may change, to a minor extent, including the storm drain system configuration,
sizing, etc.
•'1
sllglgx,7 dOgOIOJPdH
t�
EXHIBIT No. 1
r- \DENSE DENSE
x4525
,� x4$7j %457.5
k�\ 4 x24 s X,� 6EET FL13W LEAVING
_ `T E .457.6
�. ' k46$$' j /� \� --•rte` 46c'7
r ,67. +
zi6.? —� III \ ~��
x4669 `�� S `' i� \ �•� /��� \-\s���\ x46r.., ��J L/ _�
DENSE
x4594
t i. \ M�A1RPa H --"-'� � x4641 j �x �\ ��'1 —`\ N
` 1\ ,
x46 &4 1 1 \ �\ ,G 6 ; _'_
--t70— —470 \ � x X,S.:.�
1 1 .
{ %467,7 ,6c, ` � \ t l..
� ...L� t;. ....
x
%4714 4713 x Vic'
<
4
4723
— t•!4 -aPCr� I r�� l '`'-i
4 47L3
7.4
x471
\ ._tea "{fix
x467,9 \`
%, %�: X4%23 �
_ n li
%,7L I `vk4`.;',
ERM
n r
4734 —, x47!8 �.�_� � 4684 Iji ./ !.'�� +;.ae 5.'F,.-i:._` ..�.%
2 -
-� 4725
0',_ i,i x4648 1 �- s`��-A x4744. zt744 r1 +1 "i 48G7 x4744 �1 1. WY j
I�I
k469e
,4Tse, Al
l x774. '','I k4 \\ `\ x4r_4 4 '
735 \ \ x '
— q—�
X474.6 X471.5 X,7L4\
t
x477.4 477.5
L 4 4724 4754 �`�. x4\ _ x47.66
x4792 �% /^ ,'.�'�'"'®'' " -- " i. --;r. i•�
.}fi717
,..- X180 -- • 0 479 -
z47Q3 ��.� t✓ / `'..�— x�� '4 i,i, 7'
x4795 %w_.•fi
774
x!7&4.\ . l a \•.1. a T
X ' I \\ \x!76_ \ 4 \ i'-
. au. jxk I x { X4 e_� x4774 \ T'il xs756 l • '2i'°.�Tc 8!' .._X:tT�ih`
'I..
\\ ,x`trv^E� 48L3 ` X4914 X4798 1 t �^ x477.5 x 'aam 484.
ERM
GRAPHIC SCALE \
0 50 100 N,
FLOWS FOR PREDEVELOPED CONDITION
SCALE: 111 =1001 AT THE NORTH PROPERTY LINE
EXHIBIT No. 2
A VE)M14 60
GRAPHIC SCALE
0 50 100-
FLOWS FOR DEVELOPED CONDITION
AFTER LEVEL OF WATER REACHES THE SPILLWAY
SCALE: 1"=100'- (SEE SECTION A —A IN EXHIBIT No. 3)
AT THE NORTH PROPERTY LINE
EXHIBIT'No. 3
LOT B LOT LJNE
�\ 200' —I ,
PAD EL =4650
RET. WALL
LOT D
70.74'
62 74'
461.20 -1000 MR DESIGN LEVEL
- ^460.14 - -100 W DESIGN LEVEL
z
24.74'
SECTION 'A -A'
NTS
R/W LINE
LOT LINE
10" 1 20'
TC AND SWALE END
ELEV = 474.65
LOT B 3
I WAS
I r474.74
AVE 60
.0.3.v
\ u7now
TRACT WRY
6.00
TOW OF Bam 46I00'
SPILLWAY 46250' '
�Ea ST GROUND WR ACE
LOT F LOT UNE
71.00' I
475.20
1.00' fRE£BOARD 475.10
473.74 - -1000 ?R DESIGN LEVEL
- 473.38 - -100 ?R DESIGN LEVEL
LIUlru U/fM1v iii: iii/ isi�� /�7 / /. / / % /i %�YiU'i / % / / / /•!iy
INV. = 474.30 472.50
INLET ED (BEYOND) IN VARIES (FROM 38' TO 47') BOTTOM
0
SECTION 'B -B'
NIS
LOT 15
475.8 PAD &
WALL
EXHIBIT No. 5
1,000 year storm factors
1 01 -
1
Spillway Storm Precipitation As discussed in the Introduction
Section of this report, spillway design is normally for something
between the-1000 -year and the probable maximum precipitation (PMP) storm.
f
In development of spillway hydrology.all available rainfall records in
and near the watershed.should be analyzed. For preliminary lanning
Purposes only, spillway precipitation amounts can be estimated using 100
year precipitation times the factors in the following tabulation:
Return Period
(Std. Deviations *)
1,000 -Year
(5:1 to 5.9)
10,000 -Year
(6.9 to 8.2)
10 Std. Deviations
(10)`Vt
PMP
(l�)
Spillway Precipitation Factors
Ratio to the 100 -Year Event
Santa Ana Santa Margarit Whitewater
River, Basin River Basin River Basin
1.35
1.68
2.27
3.22
1.37 1.45
1.73 1.89
2.22 1 .-2.24
3.15 1 3.21
*Approximate number of standard deviations above the mean. See DWR Bulletin
- Number 195.
The tabulated factors above are based on methods presented in Depart-
ment of Water Resources (DWR) Bulletin Number 195, "Rainfall Analysis for
Drainage Design," dated-October 1976. It should be emphasized that these
factors are suitable for preliminary planning purposes only, and selection
of design precipitation values for spillways requires an in -depth analysis
of all available records and the pertinent literature..
District Frequency Analyses - The District has re ared frequency
P P
analyses for records of all available precipitation stations in and near
the District. These analyses are based on methods described by DWR in
B -2
In-Tract Hydrology and Hydraulic
Calculations
A) 100 and 10 Year Rational Method,
AMC H
Developed Condition
0')
MS., OF M ROLOGIC
Cover' Type (3) ,
SOIL - COVER COMPLEXES FOR :PERVI
Quality'0.
Cover (2)
NATURAL COVERS. -
Barren
(Rockland, eroded and graded land)
ChaParrel, Broadleaf
(Manzonita, ceanothus and scrub. oak)
Chaparrel, Narrowleaf
(Chamise and redshank)
Grass, Annual or Perennial
Meadows or Cienegas
(Areas.with seasonally high water table,
principal vegetation is-sod forming grass)
Open Brush
(Soft wood shrubs - buckwheat, sage, etc.)
Woodland
(Coniferous-or broadleaf trees Predominate.
Canopy density is at least SO. percent)
Woodland, Grass
(Coniferous or broadleaf
density from 20 to 50 trees with canopy
Percent)
URBAN COVERS _
Residential or Commercial Landscaping
(Lawn, shrubs, etc.)
Turf
(Irrigated and mowed grass)
AGRICULTURAL COVERS
Fallow
(Land Plowed but not tilled or seeded)
Poor
Fair
Good
Poor
Fair
Poor.
Fair
Good
Poor
Fair
Poor
Fair
Good
Poor
Fair
Good
Poor
Fair
Good
Poor
Fair.;,:
Good
R C F CA W C D RUNOFF INDEX
HYDROLOGY. MANUAL FOR
PER.1la0US_
LS-AMC I3
Soil
78 186 191 1.93
53
70
80
85
40
63
75
81
31
57
71
78
71
82
88.
91
55
72
81
86
67
78
86
89
50
69
79
84
38
6.1.
74
80
63
77
85
88
1
51
70
80
84
30
58
.72
78
62
76
84
88
46
66
77
83
41
63
166
75
171
81
45
83
36
60.
73
79
28
55
70
77
57.
73
82
86
44
65
77
82
33
58
72
79
32 16)169 1 75
58' 74 83 87
44 65 77' 82
33 58 72. 79
76 85 90 92
NUMBERS
AREAS
PLATE E -6.1 (1 of 2)
Riverside County Rational Hydrology Program
CIVILCADD /CIVILDESIGN Engineering Software,(c) 1989 - 2005 Version 7.1
Rational Hydrology Study Date: 05/24/07' File:rr.out
------------------------------------------------------------------------
RATIONAL METHOD
100 YEAR STORM
TTM 32348, LA QUINTA, CALIFORNIA
IN SITE FLOWS
* * * * * * * ** Hydrology Study Control Information * * * * * * * * **
English (in -lb) Units . used in input data file
------------------------------------------------------------------ - - - - --
Program License Serial Number 6019
------------------------------------------------------------------------
Rational Method Hydrology Program based on
Riverside County Flood Control & Water Conservation District
1978 hydrology manual
Storm event (year) =. 100.00 Antecedent Moisture Condition = 2
Standard intensity- duration curves
For the .[ Palm Springs ] area used
10 year storm 10 minute intensity
10. year storm 60 minute intensity
100 year storm 10 minute intensity
.100 year storm 60 minute intensity
data (Plate D -4.1)
2.830(In /Hr)
1.000(In /Hr)
= 4.520(In /Hr)
= 1.600(In /Hr)
Storm event year = 100.0
Calculated rainfall intensity data:
1 hour intensity = 1.600(In /Hr)
Slope of intensity duration curve = 0.5800
+++++++++++++++++++++++++++++++++++++++ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + ++
Process -from Point /Station 10.000 to Point. /Station 20.000
* * ** INITIAL AREA EVALUATION * * **
Initial area flow distance = 213.000(Ft.)
Top (of initial area) elevation = 77.000(Ft.)
Bottom (of initial area) elevation = 67.900(Ft.)
Difference in elevation = 9.100(Ft.)
Slope = 0.04272 s(percent)= 4.27
TC = k(0.390) *[(length ^3) /(elevation change)] ^0.2
Initial area time of concentration 6..256 min.
Rainfall intensity = 5.937(In /Hr) for a 100.0 year storm
SINGLE FAMILY (1/4 Acre Lot)
Runoff Coefficient = 0.833
(0
Decimal fraction soil group A 0.000
r Decimal fraction soil group B.= 1.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 0.000
RI index for soil(AMC 2) = 56.00
Pervious area fraction = 0.500; Impervious fraction = 0.500
Initial subarea runoff = 7.118(CFS)
Total initial stream area = 1.440(Ac.-)
Pervious area fraction = 0.500
+++++++++++++++++++++++++++++++++++++++ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + ++
Process from Point /Station 20.000 to Point /Station 30.000
* * ** STREET FLOW TRAVEL TIME + SUBAREA FLOW ADDITION * * **
Top of street segment elevation = 67.900(Ft.)
End of street segment elevation.= 62.400(Ft.)
Length of street segment. 310.000(Ft.)
Height of curb above gutter flowline = 6.0(In.)
Width of half street (curb to crown) = 18.000(Ft.)
.Distance from crown to crossfall grade break = 10.000(Ft
Slope from gutter to grade break (v /hz) 0.020
Slope from grade break to crown (v /hz) = 0.020
Street flow is on [2] side(s) of the street
Distance from curb to property line = 10.000(Ft.)
Slope from curb.to property line (v /hz) = 0.020
Gutter width = 1.500(Ft.)
Gutter hike from flowline = 0.125(In.)
Manning's N in gutter = 0.0150
Manning's N from gutter to grade break 0.0150
Manning's N from grade break to crown = 0.0150
Estimated mean flow rate at midpoint of street =
Depth of flow = 0.254(Ft.), Average velocity =
Streetflow hydraulics at midpoint of street travel:
Halfstreet flow width = 13.675(Ft.)
Flow velocity = 3.44(Ft /s)
Travel time = 1.50 min. TC = 7.76 min.
Adding area flow to street
SINGLE FAMILY (1/4 Acre Lot)
Runoff Coefficient = 0.825
Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 1.000
Decimal fraction soil group C = 0.000
Decimal f- raction soil group D = 0.000
RI index for soil(AMC 2) = 56.00
12.770(CFS)
3.441(Ft /s)
Pervious area fraction = 0.500; Impervious fraction = 0.500
Rainfall.intensity'= 5.241(In /Hr) for a 100.0 year storm
Subarea runoff = 11,199(CFS) for 2.590(Ac.)
Total runoff = 18.317(CFS) Total area = .4.030(Ac.)
Street flow at end of street = 18.317(CFS)
Half street flow at end of street = 9.159(CFS)
Depth of flow = 0.293(Ft.), Average velocity = 3.767(Ft/s)
Flow -width (from curb.towards crown)-- 15.639(Ft.)
++++++++++++++++++++++++++++++++++++++++ + + + + + + + + + + + + + + + + + + + + + + + + + +. + + ++
Process from Point /Station 30.000 to Point /Station 40.000
�j
* * ** PIPEFLOW TRAVEL TIME (Program estimated size) * * *.*
Upstream point /station elevation = 62.400(Ft.)
Downstream point /station elevation 57.000(Ft.)
Pipe length = 49.83(Ft.) Manning's N = 0.013
No..of pipes = 1 .Required pipe flow = 18.317(CFS)
Nearest computed pipe diameter = 15.00(In.)
Calculated'individual pipe flow = 18.317(CFS)
Normal. flow depth in pipe = 10.73(In.)
Flow top width inside pipe = 13.53(In.)
Critical,depth could not be calculated.
Pipe flow velocity = 19.49(Ft /s)
Travel time through pipe = 0.04 min.
Time of concentration (TCj = 7.80 min.
+++++±++++++++++++++++++++++++++++++... ... + + + + + + + + + + + + + + + + + + + + + + + + + + ++
Process from.Point /Station. 40.000 to Point /Station 40.000
*' * ** SUBAREA FLOW ADDITION * * ** -
UNDEVELOPED (poor cover) subarea
Runoff Coefficient = 0.840
Decimal•fraction soil group A = 0.000
.Decimal fraction soil group B = 1.000
Decimal fraction soil group C = 0.000
Decimal .fraction soil group.D = 0.000
RI index for soil(AMC 2) = 78.00
Pervious area fraction = 1.000; Impervious fraction = 0.000
Time of concentration = 7.80 min.
Rainfall intensity = 5.224(In /Hr) for a 100.0 year storm
Subarea runoff = 2.369(CFS) for 0.540(Ac.).
Total.runoff = 20.686(CFS) Total area = 4.570(Ac.)
End of computations, total study area = 4.57 (Ac.)
The following figures may
be used for a unit hydrograph study of the same area.
Area averaged pervious area fraction(Ap) = 0.559
Area averaged RI index number = 58.6
x Riverside County Rational Hydrology Program
CIVILCADD /CIVILDESIGN Engineering Software,(c) 1989.- 2005 Version 7.1
Rational Hydrology Study. Date: 05/24/07 File:rr.out
----------------------------------- -.------ =------------------------------
RATIONAL METHOD
10 YEAR STORM
TTM 32348, LA QUINTA, CALIFORNIA
IN SITE. FLOWS
* * * * * * * ** Hydrology Study Control Information * * * * * * * * **
English (in -lb) Units used in input data file
---------------------------------------------------------------- - - - - --
Program License Serial Number 6019
------------------------------------------------------------------------
Rational Method Hydrology Program based on
Riverside County Flood Control & Water Conservation District
1978 hydrology manual
Storm event (year) 10.00 Antecedent Moisture Condition = 2
Standard intensity- duration curves data.(Plate D -4.1)
For the [ Palm Springs ] area used.
10 year storm 10 minute intensity = 2.830(In /Hr)
10 year storm 60 minute intensity = 1.000(In /Hr)
100 year storm 10 minute intensity = 4.520(In /Hr)
100.year storm 60 minute intensity = 1.600(In /Hr)
Storm event year = 10.0
Calculated rainfall intensity data:
1 hour intensity = 1.000(In /Hr)
Slope of intensity duration curve = 0.5800
+++++++++++++++++++++++++++++++++++++++ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + ++
Process from Point /Station 10.000 to Point /Station. 20.000
* * ** INITIAL AREA EVALUATION * * **
initial area flow distance = 213.000(Ft.)
Top.(of initial area) elevation = 77.000(Ft.)
Bottom'(of initial area) elevation = 67.900(Ft.)
Difference in elevation = 9.100(Ft.)
Slope = 0.04272 s(percent)= 4.27
TC = k(0.390) *[(length ^3) /(elevation change)] ^0.2
Initial area time of concentration = 6.256 min.
f Rainfall intensity = 3.711(In /Hr) for a 10.0 year storm
SINGLE FAMILY.(1 /4 Acre Lot)
Runoff Coefficient = 0.801
Decimal fraction soil group A = 0.000
® Decimal fraction soil group B = 1.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 0.000
RI index for soil(AMC 2) = 56.00
Pervious area fraction = 0.500; Impervious
Initial subarea runoff = 4.280(CFS)
Total initial stream area = 1.440(Ac
Pervious area fraction = 0.500
fraction = 0.500
+++++++++++++++++++++++++++++++++++++++ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + ++
Process from Point /Station 20.000 to Point /Station 30.000
* * ** STREET FLOW TRAVEL TIME + SUBAREA FLOW-ADDITION * * **
Top of street segment elevation = 67.900(Ft.)
End of street segment elevation = 62.400(Ft.)
Length of street,segment = 310.000(Ft.)
Height of curb above gutter flowline = 6.0(In.)
Width of half street (curb to crown) = 18.000(Ft.)
Distance from crown to crossfall grade break = 10.000(Ft.)
Slope from gutter to grade break (v /hz) = 0.020
Slope from grade break to crown (v /hz) = 0.020
Street flow is on [2] side(s) of the street
Distance from curb to property line = 10.000(Ft.)
Slope from curb to property line (v /hz) = 0.020
Gutter width = 1.500.(Ft.)
Gutter hike from flowline = 0..125(In.)
Manning's N in gutter = 0.0150
Manning's N from gutter to grade break = 0.0150
Manning's N from grade break to crown = 0.0150
Estimated mean flow rate at midpoint of street = 7.650(CFS)
Depth of flow = 0.207(Ft.), Average velocity = 3.025(Ft /s)
Streetflow hydraulics at midpoint of street travel:
Halfstreet flow width = 11.310(Ft.)
Flow velocity = 3.03(Ft /s)
Travel time = 1.71 min. TC.= 7.96 min.
Adding area flow to street
SINGLE FAMILY (1/4 Acre Lot)
Runoff Coefficient = 0.790
Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 1.000
Decimal fraction soil group.0 = 0.000
Decimal fraction soil group D = 0.000
RI index for soil(AMC 2) 56.00
Pervious area fraction = 0.500; Impervious fraction = 0.500
Rainfall intensity = 3.226(In /Hr) for a 10.0 year storm
Subarea runoff = 6.598(CFS) for 2.590(Ac.)
Total runoff = 10.878(CFS) Total area = 4.030(Ac.)
Street flow at end of street = 10.878(CFS)
Half street flow at end of street = 5.439(CFS)
Depth of flow = 0.238(Ft.), Average velocity = 3.305(Ft /s)
Flow width (from curb towards crown)= 12.885(Ft.)
+++++++++++++++++++++++++++++++++++++++ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + ++
Process from Point /Station 30.000 to Point /Station 40.000
•
* * ** PIPEFLOW TRAVEL TIME (Program estimated size) * * **
Upstream point /station elevation = 62.400(Ft.)
Downstream point/station elevation = 57.000(Ft.)
Pipe length = 49.83(Ft.) Manning's N = 0.013
No. of pipes = 1 Required pipe flow 10.878(CFS)
Nearest computed pipe diameter = 12.00(In.)
Calculated individual pipe flow = 10.878(CFS)
Normal flow depth in pipe = 9.14(In.)
Flow top width inside pipe = 10.22(In.)
Critical depth could not be calculated.
Pipe flow velocity = 16.96(Ft /s)
Travel time through pipe = 0.05 min.
Time of concentration (TC) = 8.01 min.
+++++++++++++++++++++++++++++++++++++++ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + ++
Process from Point /Station 40.000 to Point /Station 40.000
* * ** SUBAREA FLOW ADDITION * * **
UNDEVELOPED (poor cover) subarea
Runoff Coefficient = 0.806
Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 1.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D.= 0.000
RI index for soil(AMC 2) = 78.00
Pervious area fraction 1.000; Impervious fraction = 0.000
Time of concentration = 8.01 min.
Rainfall intensity = 3.215(In /Hr) for a 10.0 year storm
Subarea runoff = 1.399(CFS) for 0.540(Ac.)
Total runoff = 12.277(CFS) Total area = 4.570(Ac.) .
End of computations, total study area = 4.57 (Ac.)
The following figures may
be used for a unit hydrograph study of the same area.
Area averaged pervious area fraction(Ap) = 0.559
Area averaged RI index number = 58.6
00,
Riverside County Rational Hydrology Program
CIVILCADD /CIVILDESIGN Engineering Software,(c) 1989 - 2005 Version 7.1
Rational Hydrology Study Date: 05/,23/07 File:RRl.out
-----------------------------------------------------------------------
RATIONAL METHOD.
100 YEAR STORM
TTM 32348, LA QUINTA, CALIFORNIA
OFF SITE FLOWS
* * * * * * * ** Hydrology Study Control Information' * * * * * * * * **
English (in -lb) Units used in input data file
Program License Serial Number 6019
------------------------------------------------------------------------
Rational Method Hydrology Program based on
Riverside County Flood Control & Water Conservation District
1978 hydrology manual
Storm event (year) = 100.00 Antecedent Moisture Condition = 2
Standard intensity- duration curves data (Plate D -4.1)
For the [ Palm Springs ] area used.
10 year storm 10 minute intensity = 2.830(In /Hr)
10 year storm 60 minute intensity = 1.000(In /Hr)
100 year storm 10 minute intensity = 4.520(In /Hr)
100 year storm 60 minute intensity = 1.600(In /Hr)
Storm event. year = 100.0
Calculated rainfall intensity data:
1 hour intensity = 1.600(In /Hr)
Slope of intensity duration curve = 0.5800
+++++++++++++++++++++++++++++++++++++++ + + +...... + + + + + + + + + + + + + + + + + + + + ++
Process from Point /Station 100.000 to Point /Station 200.000
* * ** INITIAL AREA EVALUATION * * **
Initial area flow distance 34'0."000 (Ft.)
Top (of initial area) elevation = 78.860(Ft.)
Bottom (of initial area) elevation = 74.300(Ft.)
Difference in elevation = 4.560(Ft.)
Slope = 0.01341 s(percent)= 1.34
TC = k (0.300) *[(length ^3) /(elevation change)] ^0.2
Initial area time of concentration = 7.315 min.
Rainfall intensity = 5.423(In /Hr) for a 100.0 year storm
COMMERCIAL subarea type
Runoff Coefficient = 0.885
• Decimal fraction soil group.A = 0.000
Decimal fraction soil group B = 1.000
Decimal fraction soil'group C = 0.000
Decimal fraction soil group D 000
RI index for soil(AMC .09.
Pervious area fraction = 0.100; Impervious fraction = 0.900
Initial subarea runoff =
1.632(CFS)
Total initial stream area = 0.340(Ac.)
Pervious area fraction = 0..100
End of computations, total study area = 0.34 (Ac:)
The following figures may,
be used for a unit.hydrograph study of the same area.
.Area averaged pervious area fraction(Ap) = 0.100
Area averaged RI index number = 56.0
t
• Riverside County Rational Hydrology Program
CIVILCADD. /CIVILDESIGN Engineering Software,(c) 1989 2005 Version 7.1
Rational Hydrology Study Date: 05 /23/07 File:RR1.out
---------------------------------------------------------------=--------
RATIONAL METHOD
10 YEAR STORM
TTM 32348, LA QUINTA, CALIFORNIA
OFF SITE FLOWS
* * * * * * * ** Hydrology Study Control Information * * * * * * * * **
English (in -lb) Units used in input data file
Program License Serial Number 6019
---------------------------------------------------------------
Rational Method Hydrology Program based on
Riverside County Flood Control & Water Conservation*District
1978 hydrology manual
Storm event (year) = 10.00 Antecedent Moisture Condition = 2
Standard intensity- duration curves data (Plate 0 -4.1)
For the [ Palm Springs ] area used.
10 year storm 10 minute intensity = 2.830(In /Hr)
10 year, storm 60 minute intensity = 1.000(In /Hr)
100 year storm 10 minute intensity = 4.520(In /Hr)
100 year storm 60 minute intensity = 1.600(In /Hr)
Storm event year = 10.0
Calculated rainfall intensity data:
1 hour intensity = 1.000(In /Hr)
Slope of'intensity duration curve = 0.5800
+++++++++++++++++++++++ t+++++++++++++++ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + ++
Process from Point /Station 100.000 to Point /Station .200.000
* * ** INITIAL AREA EVALUATION * * **
Initial area flow distance = 340.000(Ft.)
Top (of initial area) elevation = 78.860(Ft.)
Bottom (of initial area) elevation = 74.300(Ft.)
Difference in elevation = 4.560(Ft.)
Slope = 0.01341 s(percent)= 1:34
TC = k(0.300) *[(length ^3) /(elevation change)] ^0.2
Initial area time of concentration = 7.315 min.
f1 Rainfall intensity = 3.389(In /Hr) for a 10.0 year storm
COMMERCIAL subarea type
Runoff Coefficient = 0.879
Decimal fraction soil group A 0.000
C 0 Decimal fraction soil group B = 1.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 0.000
RI index for soil(AMC 2) = 56.00
Pervious area fraction = 0.100; Impervious fraction = 0.900
Initial subarea runoff = 1.013(CFS)
Total initial stream area = .0.340(Ac.)
Pervious area fraction = 0.100
End of computations, total study area = 0.34 (Ac.)
The following figures may
be used for a unit.hydrograph study of the same area.
Area averaged pervious area fraction(Ap) = 0.100
Area averaged RI index number = 56.0
CAP, I
B) W.S.P. G. W. for pipe
r)
T1 TTM 32348, LA QUINTA 0
T2 PIPE FROM NODE 30 TO NODE 40
T3 100 YEAR STORM
SO 1000.000 57.000 1 62.500 .
R 1049.830 58.840 1 .013.. 000
WE 1049.830 58.840 2 .500
SH 1049.830 58.840 2 58.840
CD 1 4 1 .000 2.000 .000 .000 .000 00
CD 2 2 0 .000 4.000 10.0 .000 .000 .00
Q 18.317 .0
c
06
FILE': savak.WSW W S P G W- CIVILDESIGN Version 14.06 PAGE 1
Program Package Serial Number: 1837
WATER SURFACE PROFILE LISTING Date:. 5 -24 -2007 'Time:11:22: 3
TTM 32348, LA QUINTA
PIPE FROM NODE 30 TO NODE 40
100 YEAR STORM
I Invert •1 Depth I Water I Q I Vel Vel I Energy I Super ICriticallFlow ToplHeight /IBase Wtl INo Wth
Station I Elev I (FT) .1 Elev I (CFS) I (FPS) Head I Grd.El.l Elev 1 Depth I Width IDia. -FTIor I.D.1 ZL IPrs /Pip
-I- -I- -I- -I- -I- -I- -I- -I- -I- -I- -I- -I- -I- -I
L /Elem ICh Slope I I I I SF Avel HF ISE DpthlFroude NINorm Dp I "N" I X -Fall) ZR IType Ch
' i I I I I I I I I I• I I I
1000.000 57.000 5.500 62.500 18.32 5.83 .53 63.03 .00 1.54 .00 2.000. .000 .00 •1 .0
-I- -I- -I- -I- -I- -I- -I- -I- -I- -I- -I- -I- -I- 1-
49.830 .0369 .0066 .33 5.50 .00 .91 .013 .00 .00 PIPE
i I I I I I I I I I I I I
1049.830 58.840 3.987 62.827 18.32 5.83 .53 63.35 .00 1.59 .00 2.000 OOb 00 1 .0
WALL ENTRANCE
I I I I I I I I I I I I I
1049.830 58.840 4.775 63.615 18.32 .38 .00 63.62 .00 .47 10.00 4.000 10.000 .00 0 .0
t .
uoz ;vinalvio dl1,ivdva jaarjS (,,
�01
(PI
°
m� °
�-: R.W < ° m R W
19.5' 195' .
0.5'� 19 ' 19' I
38' .. � --0.5'
3' 16:5' 3'
16.5'
— — — — — — — — — — -- —
6" WEDGE CURB.
NTS
MANNING'S EQUATION
1.486 z A z 9x S+
Q= n
In which
Q = Flow rate (cfs)
A = Area of water normal to flow (fie )
....._ _R .__ _-gydraulic radius (ft)
S = Slope of the street (ft/ft)-
n Roughness .coefficient
For section A —A
A = 6.74 ft'
R = 0:088 ft
S = 0.0118. ft /ft
n = . 0.015
Q= '14.2' cfs i Qao te.vViov1 L, A 10.1 a+$,)
I
ON SITE STREET CAPACITY
CALCULATION
SECTION A-
A
I
.O
/
.
r
,
C`A,
CJt
O
�
i
Catch Basin No.1
i
q
Sump Condition
W =10�_
—�
oil—
_
— — — — — —
/
C.11
/ ..
... ...._... _ ........ .._.
i
I
1
Catch BasinlNo.2
Q
1
/
Flow —by Con ition
I
/
W = 4'
°
�I.i
suoyv1na1m ulsvq yo;v.7 (Q
•
i
d
CA TCH BA SIN CA L CUL 4 TjLr71V
7
SUMP CENDI TIL A/
CA TCH BASIN No, I
Q = 4,3.x A x J0.6
In which
A = Area of opening= V x 10,112 (sq-f t)
Bepth of flow above normal_ .gu-tterfft>
V =
7 ft
-A
583 5f
P =
0, 6f t
Use
V =-10 ft
0/1 9517
�J'60F 0/1
4 SL 'O 7
m qj
Oj)l qlsoq do WRA OA
87
S -jPC 12
"ON ffJ aOJ
= 0141
0 'ON SNISVff H-?-Z V-?'
i
i
i
Iz4
. 0.89
10
s4
200
113
OJ34
7.0—
\
.
so
9.
-.
0
0 {cfs)
200 —
0.75
40
\
0 ��
100
a7o
30
70 �SOi�
60 0
58
SO
0.�
EXAMPLE (Sea Dashed Line) 50 30
S
-40� \
3 4.
0.0
0.55
2
Cmn = Oa fi6efs 40
3.8
-
S. IQO% 20
20
Q
Find = D = 0.55 ft. 30
A • 4.9 t
t0 zs
0 45
-
�1.0
Q.
20 .
- 2J
-0 40
103_
1.4
-0.35
Q40
as r� =_a9s
�2
0.30
(�
0.89
30
R/W !
020.
30'
C(tfs�
0.51
-025
c �— L833'� t
V.ZZ
0.09
�
Q06
I
097
0.06
02b
0
-020
OJCED -0.17
Cz
JO
oJ7`� -c•so
OJT.'
0.1 ;=-OJ5
J7
-
_
NOTE
L
-
THE 0 DET –r-Rh WED FROM THIS CHART.
IS FOR ONE HALF OF STET. OAS �
RE
0J0
{ )
P *",I
LOS ANGELES COUNTY ROAD DEPARTMENT
.
STREET FLOW
REFERENCE SHEET
LOCAL ST.- Chcrt
i
i
i
Catch Basin 'Exhibit
r j
r. M.
ool
'Catch Basin No.1 —�
J� ump on i ion ;
W = 10.i
Ij
N.
Catch Basin No.2 Q
Flow —by Con ition /.
/ W = 4' % r
i
1
I �
_I
■
I
i
i
al1s.�.�0 -
;ovrl uI -
•uoyvinp anon £
poylaur Inapoys ydvagoaPdH I1u11 (ar
0
r2l
SOIL COVER
OU TYPE
OR P
(PLATE C-1)
E31
R1
NUMBER
PLATE E-G.1)
r4l
PERVIOUS
AREA
INFILTRATION
RATE-INdHR
111(PLATE 6.2)
C53
LAND
USE'
Ok
PER E T
fflf
I �rAQA
I E IOUS
P A E E-6.3)
ryl
ABJUSIED
I FIL RTON
RATE -IN /HR
[4 31 1-. 9 [6 3 1
183
'AREA' -
SO INCHES
193
AH
0
1103
AVERAGE
A G
ADJUSTED TION
IU S T INFILTRATION
INFILTRATION
RATE-IN/HR.
/OR
1EI 3TIN
_54
iw
0.,Z?A
.4.b1
F
CD
W
Ir 10 1- 0•Z361
.VAR-1 ABLE LOSS RATE CURVE 24.-HOUR STORM ONLY)'
FM= Minimum .Loss Rate n--'F/2=IC.103/2=' IN./HR.
,n C =(F-Fjn)/54'= '(1 CIO]. — F,,j'/p42" .. .......
1.55' 11
FT = C(247-(T/60))"55 + F", (24 —(T/60)) - +
INAR,
Where:/
T =Time In minutes. To 9 T an averag value for each unit time period 1 use T= the unit time for the
first time perIod T = I . unit time for .the second period etc.
2
-,
J
M
M
C:
>. 0
If :
a .4
C
a z
0
OO.
2. a
0
0
0
a..
R C F C a W C D SYNTHETIC UNrr HYDROGRAPH METHOD Project Sowwt
HYDROLOGY unit Hydrogroph and Effective Rain tN •tyZQ�x
MANUAL Calculation. Form By Date
Chocked Date_
113 CONCENTRATION POINT NODE 4Q C2] AREA DESIGNATION
C3] DRAINAGE.AREA -SO MILES p,pp -1Z 14] ULTIMATE DISCHARGE -CFS- MRS /IN (645aC3]l
CS] UNIT TIME-MINUTES $ 16] LAG TIME- MINUTES
[73-UNIT TIME- PERCENT OF LAG (100aC5] /C6]) C8] S -CURVE
193 STORM FREQUENCY G DURATION too YEAR- 3 HOUR 1103 TOTAL ADJUSTED STORM RAIN - INCHES
1113 VARIABLE LOSS RATE (AVG)- INCHES /HOUR C123 MINIMUM LOSS RATE (FOR VAR. LOSS) -IN /HR
1133 CONSTANT LOSS RATE - INCHES /HOUR 1143 LOW LOSS -RATE- PERCENT Qfl
UNIT HYDROGRAPH EFFECTIVE RAIN
FYDRRAPH
115] 116] 117] 118] 119] C20] 121 ] 122] 123] UNIT TIME CUMULATIVE DISTRIB NIT PATTERN STORM TIME PERCENT AVERAGE GRAPH YDRGGRAPH PERCENT RAIN RATE RAINCTIVE PERIOD OF LAG PERCENT OF PERCENT FS- HRS /IN (PL E -5.9 IN /MR IN /HR IN /HR
"t 173 *1153 ULTIMATE C173T C173V C4 ]aC18] O
DISCHARGE 100 100 1213-C223
( S- GRAPH )
0
5
1
u
IZ
t3
t5
. 1b
t1
I t8
Iq
'to
2t
22
23
25
26
2�
28
29
30
3t
33
1.3
1.1
1.5
IS
1.6
Lg
k.8 '
t..s .
1.8
240
z.4
2.1.
3:3
1.1
3;0
3.1
4:'Z
-5.0
3S
6.8 .
8.2
59
z.o
1.�
to
0.312, Lvol
O.V(06
0.2-.
.,
0.4106
0.11
-
o• 343
o•Z�-
-
0. 'i106
o.Z•y.
-
0.`tib6
O.Z.+
-
o,5bz
0.460
p,Z,•}
-
562
o.2`r
-
o•�e
az�
0.2
-
o.6Bb
o.i
-
O.6i3
at
0.62.4•
p.t�
-
o.6t1
0.8�kZ
RL�
-
A-1gl1
0,
-
0. ®�'L
-
1.9
-
.0.a61
oz
-
0.561
0.2
-
I.�jtO
-
1,o4i
p�
-
2i -a
Qt.
-
2.21g
4Z+
2.55.8
d2
-
t.e�.l
0.6�{
0-L
oS6Z
02
.-
0.562
0,
O.11
o.lo
0.13
f7.13
o.z3
0.3z-
0.23
O,Z10
0.32
0.45
0.19
O,'13
0.6-1
0.'10
1 Vol..
1.3Z
v.e5
168
I .60
0.311%
0.55
IN TRACT
f
Effective rain = 22.65n/hr. x 5/60 hr
= 1.89 inches
Flood Volume = Effective rain x area .
= 1.88 in x 1/12 x 4.61 Ac.
= 0.73 Ac -ft
= 31,583 cf
1,000 year storm for Whitewater basin = 1.45 x 100' year storm
Flood volume for 1,000 year storm =1.45 x 31,583 cf = 45,795 cf
� 7
w
b
n
n
i
C = (F- FM) /54" _ (E 003 •- Fm)
FT =C(24--!-(T160))' 155 +Fm
(24 — (T /60))I.ee.+
IN. /HR.
Where:
T =Time in minutes. To gRt an average value for each unit time period,Use T= 2 the unit time for the
first time period,T =1211 unit timt 1`4 r. the second period, etc.
1
1
I
a
(I)� C2]
t3]
r4
C5]
CT]
CBJ
t9]
110]
SOIL COVER
GROUP TYPE
RI
NUMBER
PERV
AREA
BUS
LAND
USE
D CI
P RCE T
ADJUSTED
INFIL7RAA71ON
'AREA' -
�i6..Likt3 S
N7
GCB']
AVERAGE
ADJUSTED
` �.�
� l�
IDEATE C -I1
IPLATE E-6.1)
RA EIT
( PLA
ANION
. I i+
E e 6.2)
OF AnEA
I11pEIJVIOUS
TA7E E -6.3)
RAIE -IN /HR
r4 11- .018]1
AtrtS
RA7EI- iN %HRON.
17]r(03
� w
C
oto•
r 9
Cow
sk
5
.
0.0.4
7-6,.b
0.4S
0.0.+*
uu�tN.'
Sto
.SI
uNF SIN-
44
O.Ob
p, py b
f
UubV.
5Jo
o.S)
VK)b". to
0.4.(741 67.1...
0.4%t�
o.zoS
C
3
A
r Q C
V )
C
0
E III ] -_ obi
Etioa-
O.Z
-n
VARA ABLE
LOSS
RATE
CURVE
( 24. —HOUR STORM
ONLY
U
Fm•= Minimum Loss Rafe _ F/2 =1 CIO
/2 =
IN. /NR. •
S a
C = (F- FM) /54" _ (E 003 •- Fm)
FT =C(24--!-(T160))' 155 +Fm
(24 — (T /60))I.ee.+
IN. /HR.
Where:
T =Time in minutes. To gRt an average value for each unit time period,Use T= 2 the unit time for the
first time period,T =1211 unit timt 1`4 r. the second period, etc.
1
1
I
RC F C a W.0 D. SYNTHETIC UNIT HYDROGRAPH .METHOD P*000
HYDROLOGY Unit Hydrograph and Effective Rain OFF TMckc T
r
\-
MANUAL Calculation Form By Date
Checked Dote
CI] CONCENTRATION POINT C23 AREA DESIGNATION
C33 DRAINAGE AREA -50 MILES 143 ULTIMATE DISCHARGE- CFS - HRS /IN (645#[3])
153'UNIT TIME=MINUTES 5 C63 LAG TIME - MINUTES
C73 'UNIT TIME - PERCENT OF LAG (100#[53/[63)
183 S- CURVE
1103 TOTAL ADJUSTED STORM RAIN - INCHES Z.io
1121 MINIMUM LOSS RATE (FOR VAR. LOSS) -IN /HR
C93 STORM FREQUENCY t DURATION 100 YEAR- 3 HOUR
Cll] VARIABLE LOSS RATE (AVG)- .INCHES /HOUR
[133 CONSTANT
LOSS RATE-
INCHES /HOUR
0 -lot
1.143 LOW 'LOSS-•RATE-
PERCENT
40
UNIT HYDROGRAPH
EFFECTIVE
RAIN
LOOD
YDROGRAPH
[153
UNIT
TIME
PERIOD
Wil
[163
TIME
PERCENT
OF LAG
[73#1157
1173
CUMULATIVE
AVERAGE
PERCENT OF
ULTIMATE
DISCHARGE
(S- GRAPH)
C181
DISTRIB
GRAPH
PERCENT
073V C073�
C)9]
NIT
YDROGRAPH
FS- HRS /'IN
143#[.187
100
[203
PATTERN
PERCENT
(PL E -5.9
121 3
STORM
RAIN
IN /HR
0
100
[223
RATE
IN
'
/HR
1231
EFFECTIVE
IN /HR'
C213-1223 R '
C241
FLOW
CFS
i
Lo,
0.3t7- [Z0
0.11
MAX
LOW
-
Z
3
1.3
1.1
0.406
0.4ob
0,b43
0.30
O.�o
0.30
-
-
0.05
0.11
6
t 5
A 1 6
o.44416
10.4tg
0.S 67..
0.30
0.30
-
0.1'I
o. 3o
-
-
Q21
g
b.
1 S :..
1.8
1.B
0-` bb
a!5167-
O.SbZ
0.30
0.3o
--
0.7.1
0.30
-
o.Li
-
0,11
o.zp
o.` Cl
oao
l2
1.�
o,SbZ
0.30
13
t�
7.1
7-.2
0.6816
0:613(0
o 3o
0.30
-
-
-
p,3q
o �9
0.31N
15
7-2
0.1686
o.3o
16
7-0
0.107-1•
0.30
11
.2_Ic
0.611
l8
2.1
O.e4,z
0;30
0.30
030
-
0,ia
19
2.4
o � 49
10
7-1
0.1642
21
33
1.030
0.38
0.30
-
-
o �3
0.677
zti
3.1.
0.96'1
21
4
*t L
SA
0A61
1.310
1.560
0.3o
0.3o
0.30
-
-
-
1.Z6
o.gio
.1.63
1.9 $
26
3S
t.�t
o.30
o.30
29
16.16
2,ttZ
'J1
0.2.
Z.SSB
3'!
36
1.8
0..b
0.962
O.,56Z
o.t0'l
D.
oal
0.30
-
0,21
o,ioo
-
0.0
OFF SITE
Effective rain = 20.67 in/hr. x 5/60 hr
= 1.72 inches
Flood Volume = Effective rain x area
= 1.72 in x 1/12'x 0.61 Ac.
= 0.09 Ac -ft
3,814 cf
1,000 year storm for Whitewater basin = 1.45 x 100 year storm
Flood volume for 1,000 year storm = 1.45 x 3,814 cf = 5,530 cf
ffo
laval ul -
uoyv1nalva suzsvq uo�llualaw (,�
f�
In tract retention basin
Elevation
Height
Area
Volume
Accumulate Volume
Ft
Ft
Sq ft
Cf
Cft
457.0
0.0
6,989
7,964
7,964
458.0
1.0
8,940
9,961
17,925
459.0
2.0
10,983
12,050
29,975
460.0
3.0
13,117
14,230
44,205
461.0
4.0
15,343
7,957
52,162
461.5
4.5
16,486
Elevation for the bottom of the retention basin = 457.00 ft
} Elevation of the spillway = 462.50 ft
Elevation of the 100 year storm
460..14 ft
Elevation of 1,000 year storm = 461.20 ft
Off site retention basin
Elevation Height
Area
Volume
Accumulate Volume
Ft Ft
Sq ft
Cf
Cft
472.5 0.0
3,803
2,015
2,015
473.0 0.5
4,258
4,752
6,767
474.0 1.5
5,246
5,779
12,546
475.0 2.5
6,311
641
13,186
475.1 2.6
6,505
Elevation for the bottom of the retention basin = 472.50 ft
�• Elevation of the spillway = , 474.74 ft
Elevation of the 100 year storm = 473.38 ft
Elevation of 1,000 year storm = 473.74 ft
Hydrology Maps
In tract.'
Off site
.
�P. )