_MES Pumping (10330).xlsx

	A	B	C	D	E
1	MZ
2
3		Reference	Calculation	Output
4
5
6			Catchment Area	57.8	ha
7
8			Design Protection Level
9			Design protection level	5	yr ARI
10			Checking	100	yr ARI
11
12
13			Inflow Hydrographs
14		Chapter 2	The design discharges estimation adopted using Rational Hydrograph Method
15
16	Equation 2.4	Chapter 2	The computed average runoff coefficient	0.65
17
18		Chapter 2	The time of concentration for the catchment at the outlet point, tc	48	min
19
20			The hydrographs for the longer duration than the time of concentration are also considered because for the sizing of the pumps and storage the total volume of runoff is also an important design parameter to be considered
21
22		Chapter 2	The rainfall intensity adopted is from the Revised Hydrological Procedure no.1 (2010) for Station 3015001 (Puchong Drop, K Lumpur)
23
24			The computed peak discharges and inflow hydrograph using Rational Hydrograph Method	Table 19.B1
25
26
27			Estimate Storage Volume and Stage-Storage Relationship
28			Total available storage from elevation 16.5 mRL to 19.5mRL (provide 0.5 m freeboard with platform level at 20.0 mRL) is about.	Figure 19.B2
29			Required storage, Vs	2832	m3
30
31
32			The Stage-Storage for the pump sump storage and channel storage	Table 19.B2
33				Figure 19.B3
34
35
36
37			Estimate Pumping Rate and Number of Pumps
38		Section 2.3.2	Runoff volume for 48 min rainstorm, based on Figure 19.B4	Figure 19.B4
39			Vt (1/2 x 96 min x 9.08 m3/s)	26163.74992	m3
40
41			Qp (Vt/48 min x 60)	9.08463539	m3/s
42
43		Equation 19.A1	Delta Q	2.98885008
44
45			Estimated required pumping rate (Qp - DeltaQ)	6.09578531	m3/s
46				Figure 19.B4
47			From this analysis, provides	3 x 2 m3/s submersible axial pumps
48
49
50			Estimate the Total Dynamic Head
51			Assuming that the lowest and highest levels the pumps need to pump are 16.5 mRL and 19.5 mRL respectively and the weir level need to pump over is 21.5 mRL as given in Figure 19.B3, hence the maximum and minimum static heads are as follows:
52			Higher level that needs to be pumped	21.5	m
53			Highest level of storage	19.5	m
54			Lowest level of storage	16.5	m
55			Hs (max) = 21.5 - 16.5	5	m
56			Hs (min) = 21.5 - 19.5	2	m
57
58			It is assumed that the diameter of the column pipe, D is 1 m and for 2 m3/s discharge the velocity head is:
59			Assumed D	1	m
60			Assumed Q	2	m3/s
61			Velocity (v) = Q/A	2.546479089	m/s
62			hv = v^2/2g	0.3305074288	m
63
64			The friction head is approximated using the Hazen-William equation. It is assumed that the column pipe is 4 m length and for steel pipe, the friction factor C is 100:
65			Assumed length of column pipe	4	m
66			Steel friction factor, C	100
67			hf = 6.83.v^1.85.L/(C^1.85.D^1.165)	0.03072344466	m
68
69			With all the above, the maximum and minimum Total Dynamic Head can be computed as follows:
70			TDH (max) = 5m + 0.33m + 0.03m	5.361230873	m
71			TDH (min) = 2m + 0.33m + 0.03m	2.361230873	m
72
73
74			Selection of Pump Performance Curve
75			With the pumping rate and TDH requirements, the pump performance curve can be selected and the pump chosen that suits the requirements	Figure 19.B5
76
77			Pump Start - Stop Levels and Stage - Pump Discharge Relationship
78			The design start - stop levels for the pump	Table 19.B3
79
80			From the start - stop lebels of the pumps, pump performance curve and TDH, the stage - pump discharge reationship
81			1. Water level rising in the pump sump storage	Table 19.B4
82			2. Water level dropping in the pump sup storage	Table 19.B5
83
84			The stage-pump discharge relationship plot	Figure 19.B6
85
86
87			Routing of Pump Sump Storage
88			With the Stage - Storage and Stage - Discharge Relationships, routing procedure similar to pond routing as elobarated in Chapter 2 is engaged to determine the water level in the pump sump storage. The only difference is that as mentioned earlier, there are two different Stage - Pump Discharge Relationships for the water lebel rising and dropping conditions due to te different start - stop levels of the pumps
89
90			The routing procedure to obtain the pump discharge and water level in the pump sump storage for the 5-year ARI 48 min inflow hydrograph and the maximum water level in the pump sump storage (lower than the design 19.50 mRL)	Table 19.B6
91			Highest Water Level	19.31	m
92			Water Level at 48 min	18.84	m
93
94			The routing is plotted:
95			1. 5 year ARI	Figure 19.B7
96
97
98
99			Discussion
100			From the pump routing analysis, the pumps provided are sufficient to meet the 5-year ARI flood protection criterion for Kampung Pasir Baru. The checks done on 100-year ARI review that the flood level is 0.7 m above the platform level of 20 mRL and the maximum inundation period is about 50 min. It can be deduced from the analysis that it is sufficient to design for the pump station to cater for 5 to 10-year ARI protection where even during 100-yar ARI rainstorm, the flooding will not be severe. With this, the capital cost can be optimised.