Transcript
HEROES
CONSULTANT
No. 3005, Tingkat Bawah, Desasiswa Lembaran, Universiti Sains Malaysia, 14300 Nibong Tebal, Pulau Pinang.
INTRODUCTION Foreword In professional project practice it can be divided into five chapters like earthwork design, water reticulation design, drainage drainage and culvert design, road design and sewerage. In this project we conducted drainage and culvert design. This chapter will explain how the drainage system is designed, the process involved and the consideration taken. In geomorphology, a drainage system is the pattern formed by the streams, rivers, and lakes in a particular watershed. They are governed by the topography of the land, whether a particular region is dominated by hard or soft rocks, and the gradient of the land. A drainage system in agriculture is an intervention to control water logging aiming at soil improvement for agricultural production. A drainage system for industrial and residential is a facility to dispose of liquid waste. An effective drainage system must be planned, analyzed and designed which is very essential to control the quantity, quality, timing, distribution of runoff resulting from storm events and also to control the erosion. Besides, the capacity of storm water that flows through the drainage structures must be analyzed to determine their ability to convey the developed discharge to avoid flooding. Therefore, the process of designing the drainage system should be considered to the parameter such as the depth of drain, area of developed, the material used for the structure and other factors that can affect the performance of designed drainage system. In designing the drainage system, the concepts that have being used are according to standard in MASMA. Many problems in Malaysia related to urban water management has using
HEROES
CONSULTANT
No. 3005, Tingkat Bawah, Desasiswa Lembaran, Universiti Sains Malaysia, 14300 Nibong Tebal, Pulau Pinang.
MASMA (Urban Stormwater Management Manual Malaysia) which has been introduced by the government through JPS (Jabatan Pengaliran Dan Saliran) since 2001. Generally, these manual act as a guideline to manage and plan good stormwater and drainage system especially in urban and develop area. OBJECTIVE There are several objectives that have been made to meet in designing the drainage system for this project:
a. To provide complete calculation and design detail for an effective minor conveyance system for residential discharge and stor m water. b. To determine appropriate size of drain for the proposed system that can cater a maximum flow rate for ARI of 5 years. c. To understanding the basic concept and procedure in design the size of drainage system that can accommodate to the t he peak flow capacity by using MASMA. d. To provide an effective drainage system that following the standard that is provided in MASMA. e. To provide for public and private property convenience and safety from flooding.
HEROES
CONSULTANT
No. 3005, Tingkat Bawah, Desasiswa Lembaran, Universiti Sains Malaysia, 14300 Nibong Tebal, Pulau Pinang.
DESIGN CRITERIA AND ASSUMPTIONS Hydrological Calculation of Catchment For estimating the catchment runoff in urban or built up area, reference were made to the Rational Method outlined in ³DID ± urban stormwater Management Manual For Malaysia´ which relate peak runoff to rainfall intensity through a proportional factor. The formula is as follows: y
Qy = C. It. A 360 3
Where; Qy = y year ARI peak flow (m /s) C
= dimensionless runoff coefficient
y
= y year ARI average rainfall intensity over time of concentration, tc, (mm/hr)
A
= catchment area (ha)
It
Rainfall intensity. I
Overland flow time of concentration using equat ion below:
Adopted time of concentration, tc = to + td
HEROES
CONSULTANT
No. 3005, Tingkat Bawah, Desasiswa Lembaran, Universiti Sains Malaysia, 14300 Nibong Tebal, Pulau Pinang.
Polynomial expressions in the form of equat ion 13.2 (DID-Urban Stormwater Manual for Malaysia) have been used in determining of design rainfall intensities Ln
( R It ) = a + b. Ln (t) + c.(ln (t))² + d (ln (t))³
where, ( R It )
=
the average rainfall intensity (mm/hr) for ARI and duration t.
R
=
average return interval (years)
T
=
duration (minutes)
a to d are fitting constant dependent on ARI
The design rainfall depth pd for a short duration d (minutes) is given by, when t < 30minutes Pd = P30 ± FD (P60 ± P30)
Where P30, P60 are the 30-minute and 60-minute duration rainfall depths respectively, obtained from the published design curve. FD is the adjustment factor for storm duration.
Runoff Coefficient, C
Recommended runoff coefficient (C) values for rainfall intensities ( I ) of up to 200mm/hr have been obtained from Design Chart 14.3 (urban area), (DID-Urban Stormwater manual for Malaysia) respectively. For I > 400mm/hr, a value of C = 0.9, should be used for all types of ground cover. For I values between 200 and 400mm/hr, interpolation between the applicable C values I = 200mm/hr and I = 400m/hr has been used.
HEROES
CONSULTANT
No. 3005, Tingkat Bawah, Desasiswa Lembaran, Universiti Sains Malaysia, 14300 Nibong Tebal, Pulau Pinang.
HYDRAULIC ANALYSIS
Design storm
Open drain has been designed to cater for flows up to and including the minor system design ARI as specified in Table 4.1
Minor System
-
5 years
Major System
-
50 years
Velocity
The velocity of design should be in the range of 0.6 m/s < v < 4 m/s. if the condition is not fulfilled, the design of the drain is assumed fail.
Drain capacity
Open and swale drain have been sized by using Manning¶s formula equation. Q = (1/n) x AR 2/3 S1/2
HEROES
CONSULTANT
No. 3005, Tingkat Bawah, Desasiswa Lembaran, Universiti Sains Malaysia, 14300 Nibong Tebal, Pulau Pinang.
Step to determine rainfall intensity
HEROES
CONSULTANT
No. 3005, Tingkat Bawah, Desasiswa Lembaran, Universiti Sains Malaysia, 14300 Nibong Tebal, Pulau Pinang.
HYDROLOGICAL CALCULATION OF CATCHMENT AND HYDRAULIC CALCULATIONS FOR DRAINAGE SYSTEM HYDROLOGICAL CALCULATION OF CATCHMENT
Swale drain
DRAIN 1 DESIGN OF DRAIN IN ACCORDANCE TO URBAN STORM MANAGEMENT MANUAL FOR MALAYSIA Total pervious area of site
=
0.05
ha
Total impervious area of site =
0.028
ha
Determine overland flow time of concentration overland sheet flow to basin
L
=
9.87
m
S
=
2
%
to
=
to
=
1/3
107nL
Assume velocity in the drain, V =
=
0.003
1/2
/S
4.87
min
1
m/s
Ld
=
47.2
m
td
=
0.79
min
Adopted time of concentration, tc =
n
5.66
min
Based on volume 4-chapter 13 of the urban storm m anagement manual on design rainfall, the polynomial approximation of the IDF curves is as followed: R
Ln( lt) = a + b ln(t) +c (ln(t)2) + d (ln(t)3)
HEROES
CONSULTANT
No. 3005, Tingkat Bawah, Desasiswa Lembaran, Universiti Sains Malaysia, 14300 Nibong Tebal, Pulau Pinang.
Where: R
lt
=
the average rainfall intensity (mm/hr) for ARI and duration t
R
=
average return interval (years)
t
=
duration (min)
a - d fitting constants depending on ARI
State
Location
Data period
Perak
Bagan Serai
1960 1983
ARI (Year) 2 5 10 20 50 100
Coefficient of the IDF polynomial constants a b c d 4.1689 0.816 -0.2726 0.0149 4.7867 0.4919 -0.1993 0.0099 5.276 0.2436 -0.1436 0.0059 5.661 0.0329 -0.0944 0.0024 5.3431 0.3538 -0.1686 0.0078 5.3299 0.4357 -0.1857 0.0089
The design storm for the durations of time of concentr ation, Tc ; Pervious area
Impervious area
I(5yrs,30) = I(5yrs,60) =
94.04 62.75
mm/hr mm/hr
P30 =
47.02
mm
P60 =
62.75
mm
I(5yrs,30) = I(5yrs,60) =
94.04 mm/hr 62.75 mm/hr
P30 =
47.02
mm
P60 =
62.75
mm
Duration
P24h West Coast (120mm)
5 10 15 20 30
1.85 1.13 0.72 0.42 0
t t
= =
30 60
HEROES
CONSULTANT
No. 3005, Tingkat Bawah, Desasiswa Lembaran, Universiti Sains Malaysia, 14300 Nibong Tebal, Pulau Pinang.
The design rainfall depth for short d is given by equation 13.3 : Pd = P30 - FD(P60 - P30)
Pervious area
Impervious area
FD
=
1.85
Pd
=
17.92
mm
=
190.07
mm/hr
I(5yrs, tc)
FD
=
1.85
Pd
=
17.92
=
190.07
I(5yrs, tc)
mm mm/hr
Values of FD for equation 13.3 Duration (min)
West Coast
East Coast
100
120
150
180
All
5
2.08
1.85
1.62
1.40
1.39
10
1.28
1.13
0.99
0.86
1.03
15
0.80
0.72
0.62
0.54
0.74
20
0.47
0.42
0.36
0.32
0.48
30
0.00
0.00
0.00
0.00
0.00
Pervious area
C
=
0.62
Q
=
0.0164
Impervious area cumec
C
=
0.9
Q
=
0.013
cumec
Determination of drain capacity : T = B +2ZY T
=
A = Y(B + T)/2 3.00
m
A
=
0.54
2 1/2
+ (1 + Z2 ) }
=
3.07
P = B + Y{(1 + Z1 )
2 1/2
2
P
4
Channel area, A
=
0.54
m
m
m
m
R=A/P R
=
0.18
side slope (H : V)
=
1
:
channel slope, S
=
0.002
Channel wetted perimeter, P
=
3.074
manning roughness, n
=
0.035
Hydraulic radius, R
=
0.176
base width, B
=
0.6
2
HEROES
CONSULTANT
No. 3005, Tingkat Bawah, Desasiswa Lembaran, Universiti Sains Malaysia, 14300 Nibong Tebal, Pulau Pinang.
top width water depth, Y
= =
Q = (1/n) x A x R
2/3
Q V = Q/A
1/2
x So
V
3 0.3 ,
=
0.2164
=
0.401
Q
=
cumec
>
0.2164
Q peak
OK!
,
Q peak
=
0.0297
m/s
Calculation of Q pre (before construction) DESIGN OF DRAIN IN ACCORDANCE TO URBAN STORM MANAGEMENT MANUAL FOR MALAYSIA Total pervious area of site
=
1
ha
Adopted time of concentration, tc tc
where
=
Fc x L / A
1/10
1/5
xS
tc
=
min
L
=
length flow path to outlet (km)
L
=
0.07
S
=
slope
S
=
5.02
A
=
catchment area, (ha)
A
=
1
ha
=
92.5 (ha) , 58.5 2 (km )
Fc
=
58.5
km
Fc
data
tc
=
5.672
min
km
2
HEROES
CONSULTANT
No. 3005, Tingkat Bawah, Desasiswa Lembaran, Universiti Sains Malaysia, 14300 Nibong Tebal, Pulau Pinang.
Based on volume 4-chapter 13 of the urban storm m anagement manual on design rainfall, the polynomial approximation of the IDF curves is as followed: R
Ln( lt) = a + b ln(t) +c (ln(t)2) + d (ln(t)3) Where: R
lt = the average rainfall intensity (mm/hr) for ARI and duration t R = average return interval (years) t = duration (min) a - d fitting constants depending on ARI
State
Location
Perak
Bagan Serai
Data period
1960 1983
ARI (Year) 2 5 10 20 50 100
Coefficient of the IDF polynomial constants a b c d 4.1689 0.816 -0.2726 0.0149 4.7867 0.4919 -0.1993 0.0099 5.276 0.2436 -0.1436 0.0059 5.661 0.0329 -0.0944 0.0024 5.3431 0.3538 -0.1686 0.0078 5.3299 0.4357 -0.1857 0.0089
The design storm for the durations of time of concentr ation, Tc ;
Pervious area
I(5yrs,30) = I(5yrs,60) =
107.28
mm/hr
71.60
mm/hr
P30 =
53.64
mm
P60 =
71.60
mm
Duration
5 10 15 20 30
P24h West Coast (120mm) 1.85 1.13 0.72 0.42 0
t
=
30
t
=
60
HEROES
CONSULTANT
No. 3005, Tingkat Bawah, Desasiswa Lembaran, Universiti Sains Malaysia, 14300 Nibong Tebal, Pulau Pinang.
The design rainfall depth for short d is given by equation 13.3 : Pd = P30 - FD(P60 - P30) Pervious area
FD
=
1.85
Pd
=
20.42
I(5yrs, tc)
=
216.05
mm mm/hr
Values of FD for equation 13.3 Duration (min) 100
West Coast 120
150
180
East Coast All
5
2.08
1.85
1.62
1.40
1.39
10
1.28
1.13
0.99
0.86
1.03
15
0.80
0.72
0.62
0.54
0.74
20
0.47
0.42
0.36
0.32
0.48
30
0.00
0.00
0.00
0.00
0.00
Pervious area
C
=
0.64
Q pre
=
0.384
cumec
Calculation of result Drain
Q pervious
Q impervious
Qtotal
1
0.016
0.013
0.030
2
0.011
0.005
0.016
3
0.010
0.006
0.016
4
0.016
0.013
0.029
5
0.016
0.000
0.016
6
0.010
0.000
0.010
7
0.011
0.016
0.027
8
0.008
0.010
0.018
9
0.027
0.042
0.069
10
0.022
0.000
0.022
11
0.022
0.000
0.022
Q post
=
0.233
HEROES
CONSULTANT
No. 3005, Tingkat Bawah, Desasiswa Lembaran, Universiti Sains Malaysia, 14300 Nibong Tebal, Pulau Pinang.
12
0.016
0.011
0.027
13
0.011
0.012
0.023
C1
0.000
0.014
0.014
C2
0.000
0.014
0.014
Q post total
0.233
=
0.384
>
Q post
OK
Concrete drain
DESIGN OF DRAIN IN ACCORDANCE TO URBAN STORM MANAGEMENT MANUAL FOR MALAYSIA Total impervious area of site =
0.07
ha
Determine overland flow time of concentration overland sheet flow to basin L
=
2.5
m
S
=
2
%
to
=
107nL
/S
to
=
13.35
min
1
m/s
Assume velocity in the drain, V =
1/3
Ld
=
27
td
=
0.45
n
=
0.013
1/2
m min
Adopted time of concentration, tc =
13.80
min
Based on volume 4-chapter 13 of the urban storm m anagement manual on design rainfall, the polynomial approximation of the IDF curves is as followed: R
Ln( lt) = a + b ln(t) +c (ln(t)2) + d (ln(t)3) Where: R
lt R t
= = =
the average rainfall intensity (mm/hr) for ARI and duration t average return interval (years) duration (min)
a - d fitting constants depending on ARI
HEROES
CONSULTANT
No. 3005, Tingkat Bawah, Desasiswa Lembaran, Universiti Sains Malaysia, 14300 Nibong Tebal, Pulau Pinang.
State
Perak
Location
Data period
ARI
Coefficient of the IDF polynomial constants
(Year)
a
b
c
d
2
4.1689
0.816
-0.2726
0.0149
5
4.7867
0.4919
-0.1993
0.0099
Bagan
1960
10
5.276
0.2436
-0.1436
0.0059
Serai
-
20
5.661
0.0329
-0.0944
0.0024
1983
50
5.3431
0.3538
-0.1686
0.0078
100
5.3299
0.4357
-0.1857
0.0089
The design storm for the durations of time of concentr ation, Tc ; Pervious area
Impervious area
I(5yrs,30) =
94.04
mm/hr
I(5yrs,60) =
62.75
mm/hr
P30 =
47.02
mm
P60 =
62.75
mm
I(5yrs,30) =
94.04
mm/hr
I(5yrs,60) =
62.75
mm/hr
P30 =
47.02
mm
P60 =
62.75
mm
Duration
P24h West Coast (120mm) 1.85 1.13 0.72 0.42 0
5 10 15 20 30
The design rainfall depth for short d is given by equation 13.3 : Pd = P30 - FD(P60 - P30) Impervious area
FD
=
1.85
Pd
=
17.92
mm
I(5yrs, tc)
=
77.9
mm/hr
t
=
30
t
=
60
HEROES
CONSULTANT
No. 3005, Tingkat Bawah, Desasiswa Lembaran, Universiti Sains Malaysia, 14300 Nibong Tebal, Pulau Pinang.
Values of FD for equation 13.3 Duration (min)
West Coast
East Coast
100
120
150
180
All
5
2.08
1.85
1.62
1.40
1.39
10
1.28
1.13
0.99
0.86
1.03
15
0.80
0.72
0.62
0.54
0.74
20
0.47
0.42
0.36
0.32
0.48
30
0.00
0.00
0.00
0.00
0.00
Impervious area
C
=
0.9
Q
=
0.014
cumec
Drainage design design discharge, Q post =
0.014
try U drain size
b=
300
m3/s
mm
Manning equation 2/3
1/2
Q = AR So /n
b
=
2y
y
=
b/2
y
=
150
mm
2
area of cross section, A =
by
=
0.045
m
S
=
0.002
Wetted perimeter, P
b +2y
=
0.6
m
n
=
0.013
Hydraulic radius, R =
= A/P
Capacity, Q =
=
0.075
0.029
m3/s
>
0.645
m/s
<
300
mm
0.003
m3/s
Velocity, V = Q/A V
use size
=
300
mm
x
4
m/s
OK
OK
HEROES
CONSULTANT
No. 3005, Tingkat Bawah, Desasiswa Lembaran, Universiti Sains Malaysia, 14300 Nibong Tebal, Pulau Pinang.
Example of calculation of invert level Ground level, GL = Depth = Gradient =
1.2 1
3.2
m
m
fall = length x gradient :
500
IL2 = IL1 - fall
Drain 1 Length = IL1
IL2
=
47 GL
m
-
depth
=
2
m
=
2
-
=
1.906
m
0.094
Drain 2 Length = IL3
drain 1 2 3 4 5 6 7 8 9 10 11 12 13
22
=
1.906
-
=
1.862
m
slope 0.002 0.002 0.002 0.002 0.002 0.002 0.002 0.002 0.002 0.002 0.002 0.002 0.002
IL = invert level
m 0.044
invert level(m) 1.906 1.862 1.822 1.742 1.972 1.902 1.826 1.776 1.804 1.946 1.946 1.940 1.884
HEROES
CONSULTANT
No. 3005, Tingkat Bawah, Desasiswa Lembaran, Universiti Sains Malaysia, 14300 Nibong Tebal, Pulau Pinang.
CATCHMENT AREA
HEROES
CONSULTANT
No. 3005, Tingkat Bawah, Desasiswa Lembaran, Universiti Sains Malaysia, 14300 Nibong Tebal, Pulau Pinang.
HEROES
CONSULTANT
No. 3005, Tingkat Bawah, Desasiswa Lembaran, Universiti Sains Malaysia, 14300 Nibong Tebal, Pulau Pinang.
HEROES
CONSULTANT
No. 3005, Tingkat Bawah, Desasiswa Lembaran, Universiti Sains Malaysia, 14300 Nibong Tebal, Pulau Pinang.