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PEMODELAN SKENARIO BARU DALAM SISTEM
DISTRIBUSI AIR MINUM KOTA BANDUNG TAHUN 2010
NEW SCENARIO MODELLING IN WATER DISTRIBUTION
SYSTEM AT BANDUNG CITY IN 2010
Miranti Mayangsari1) and Rofiq Iqbal
2)
Program Studi Teknik Lingkungan Fakultas Teknik Sipil dan Lingkngan ITB
Jl. Ganesha No.10 Bandung 40132 1)[email protected],
Abstract : In order to increase public clean water service, PDAM Kota Bandung has a
clean water supply development scenario that scheduled be applied in 2010. A new water
treatment plant (WTP) Cimenteng will be built in South Bandung, existing transmission
pipelines from Cisangkuy river will be reorganized, and transmission pipeline from PLTA
Dago Bengkok II will be constructed to the current Badak Singa water treatment plant. The
new scenario adds 1.000 L/s to the PDAM water supply. This research is aimed to build a
model of the new scenario of water distribution network with extension service area.
Service areas extension is made in Gedebage as an allocation extension area from PDAM
and South Bandung area (Mengger and Margahayu) considering its high pressure residue.
Key words : water supply, distribution, modeling, EPANET 2.0
Abstrak : Dalam rangka peningkatan mutu pelayanan, PDAM Kota Bandung memiliki
scenario pengembangan sistem penyediaan air bersih yang direncanakan akan
diaplikasikan pada tahun 2010. Pembangunan Instalasi Penyediaan Air Minum (IPA)
Cimenteng di Bandung Selatan, rekonstruksi sistem transmisi eksisting dari Sungai
Cisangkuy dan pembangunan jalur transmisi dari PLTA Dago Bengkok menuju instalasi
penyediaan air minum Badak Singa akan dilakukan. Dengan adanya skenario baru ini,
produksi air minum Kota Bandung akan bertambah sebesar 1.000 L/s. Dalam penelitian ini
dilakukan pemodelan sistem distribusi air minum dengan rencana scenario baru untuk
menentukan perluasan daerah pelayanan. Pengembangan wilayah pelayanan dilakukan di
daerah Gedebage sebagai daerah yang dialokasikan untuk dilakukan pengembangan
jaringan distribusi dan area Bandung Selatan (Mengger dan Margahayu) dimana masih
terdapat sisa tekan yang besar.
Kata kunci : penyediaan air minum, distribusi, pemodelan, EPANET 2.0
INTRODUCTION
For a community that has good life standard, clean water needs usually
provided by a communal water supply system. Water supply system represents a
holistic service system, which is consists of three main components, water source,
transmission and distribution.
There are some important considerations on distributing clean water to the
consumer; they are pressure, quality, quantity and continuity. The term distribution
system is used to describe collectively the facilities used to supply water from its
source to point of usage. To deliver water to individual consumers with appropriate
quality, quantity, and pressure in a community setting requires an extensive system
of pipes, storage reservoirs, pumps, and related appurtenances.
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In Bandung city, clean water provided by PDAM Kota Bandung, a
governmental organization taking care water supply. Yet, nowadays PDAM Kota
Bandung has not been able to fulfill the needs of clean water for whole population.
PDAM Kota Bandung can serve only 65% from total Bandungs population
(PDAM, 2006). Besides that, almost all parts of service zone still applying supply
intermittent distribution method.
In terms to increase society clean water service, PDAM Kota Bandung has
clean water supply development scenario that scheduled be applied in 2010. A new
water treatment plant (WTP) Cimenteng will be built in South Bandung, existing
transmission pipelines from Cisangkuy river will be reorganized, and transmission
pipelines from PLTA Dago Bengkok II will be constructed to the current
Badaksinga water treatment plant. This whole scenario adds 1.000 L/s to the PDAM
water supply.
With the new scenario of clean water supply in 2010, the distribution
network needs to be adjusted. Network model which replicate the dynamics of an
existing or proposed system, is required to see the change caused by the increasing
production capacity, such as network extension possibilities, and adjustments that
need to be made. Models can be used to predict system responses to events under a
wide range of conditions without disrupting the real system. Using models,
problems can be anticipated in proposed or existing systems, and solutions can be
evaluated before time, money, and materials are invested in a real-world project.
Modeling itself is the imitation process of a systems particular character into
another function. There are several reasons why simulation (model development) is
important to do (Walski, et.al, 2001) :
Impracticality if the experiment is being done on the real system
The ability to evaluate the system before development
Ability to predict the response from the system in different condition without
ruining the actual system
In selecting a computer program, one should keep several considerations in
mind. These include (Walski, et.al, 1984) :
Steady state versus extended period simulations
Simulation versus optimization
Ease of making the program operational
User-friendliness with respect to input and output
Clear error message
Numerical method used for solution
Head loss equation used
EPANET 2.0 is a software that creates hydraulic simulation on certain range
of time in a pressured pipe network. The network itself consists of pipes, nodes,
pumps, valves, tanks and reservoirs. EPANET 2.0 has the ability to track water flow
in pipe, pressure on each node, water level in tank and concentration of chemical
specimen during simulation time. As a Windows operating system based software,
EPANET 2.0 provide integrated environment and equipment to input or edit data, to
operate hydraulic and water quality simulation, and to present the simulation result
in many form (table, graph, contour map, etc). (Rossman, 2000)
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METHODOLOGY
Methodology used in this research are :
1. Problem Identification and Literacy View
This research procedure begins from literature study of things related to
community water supply and distribution systems modeling. Problems
identification is done through scrutinize existing water distribution system
and water supply development plan in Bandung city.
2. Data Collection
Data needed in this research are Bandung city map, contour map, inhabitant
population data, primary distribution network map, network density map,
raw water production data, water metering data, and distribution systems
data inventory.
Secondary data collected from several institutions such as PDAM Kota
Bandung, BAPPEDA Kota Bandung, Dinas Kependudukan dan Pencatatan
Sipil Kota Bandung, Badan Koordinasi Survey dan Pemetaan Nasional, and
Dinas Tata Ruang dan Wilayah (Distarkim).
3. Data Calculations
Data needed to be calculated before making water distribution systems
simulations are :
Hazen William pipe carrying capacity factor (C)
Higher C-factors represent smoother pipes (with higher carrying
capacities) and lower C-factors describe rougher pipe. Three main
factors should be considered in determining Hazen William C factor :
pipes material, pipes diameter, and pipes age. Based on pipes diameter,
the bigger diameter pipes, the higher C factor is, and so the other way.
Based on pipes age, the older pipes, the lower C factor would be, and
so on the contrary.
Water usage and water demand
With the usage water data from Water Metering Record PDAM
Bandung, water consumption in every district can be count then
divided based on pipe density so water consumption for every node
can be determined.
Water demand in 2010 is projected based on population growth (1.75%
per year) and 175 l/o/h demand per capita (RTRW Kota Bandung
2013).
4. Drawing Water Distribution Network in Epanet 2.0
Water distribution network is re-drawed into software Epanet 2.0. This
process includes determining the node points and systematic pipes
numbering, which is followed by input the length and diameter of the pipe
and node points elevation.
5. Node Loading Determinations
There is no such standard method in determining node loading amount.
Amount of node loading can be determined by estimating district loading
based on network density. The denser one network, the higher node loading
is, and so on the contrary. After water usage in every district can be
determined, district loading divided to each node.
6. Simulation of Development Condition Year 2010
Model simulation is made after all data input parameter finished inserted.
Simulation development is based on secondary data and several
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assumptions. Simulation made with 1.000 lps additional production capacity
from new water sources.
In the simulations, extension is made to the new allocated service area with
relatively high pressure residue. One of the consideration is thar service area
with high pressure residue makes it possible to supply water to further area.
GENERAL DESCRIPTION OF PDAM BANDUNG WATER SUPPLY
SYSTEM (EXISTING AND DEVELOPMENT PLAN)
PDAM Bandung applies a combination system of water delivery, loop
system and branch system. On piping network, pipes with large diameter are
connected one to another. With connected pipe, it will be easier to deliver water to
the unsupplied area or to the area with low level of pressure residue.
At present PDAM Kota Bandung receives 2370 lps raw water that is
derived from several rivers and wells.
The percentage of leakage in PDAM Bandungs water distribution system
reach 51% from its total production capacity at present, while tolerable level of
leakage on a water distribution system is approximately 18%-20%. Table 1 shows
water losses in Bandung city distribution network.
Table 1. Water Losses in Bandung City Distribution Network (PDAM Bandung, 2007)
Month Production Distribution Usage Water Losses Loss Percentage
(m3) (m
3) (m
3) (m
3) %
January 6,945,065 6,668,476 2,891,704 3,776,772 56.64%
February 6,223,220 5,974,850 2,826,281 3,148,569 52.70%
March 7,002,578 6,724,610 3,245,766 3,478,844 51.73%
April 6,969,804 6,702,955 3,495,101 3,207,854 47.86%
May 7,343,727 7,061,770 3,233,637 3,828,133 54.21%
June 7,152,303 6,876,203 3,400,867 3,475,337 50.54%
July 7,402,395 7,115,726 3,361,107 3,754,619 52.77%
August 7,428,670 7,142,898 3,395,886 3,747,012 52.46%
September 7,058,811 6,791,062 3,387,125 3,403,938 50.12%
October 7,164,409 6,884,841 3,110,062 3,774,779 54.83%
Navember 7,031,159 6,758,870 3,666,362 3,092,508 45.75%
December 7,158,393 6,887,984 3,460,616 3,427,367 49.76%
Average 7,073,378 6,799,187 3,289,543 3,509,644 51.61%
In terms to increase society clean water service, PDAM Kota Bandung has
clean water supply development plan that scheduled be applied in 2010 : a new
water treatment plant (WTP) Cimenteng will be built in South Bandung, existing
transmission pipelines from Cisangkuy river will be reorganized, and transmission
pipelines from PLTA Dago Bengkok II will be constructed to the current
Badaksinga water treatment plant.
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EXISTING PROPOSED
Cikapundung III Cikapundung III Dago Bengkok II
Badaksinga WTP Badaksinga WTP
Cisangkuy River (Bak Prased II) Cisangkuy River (Bak Prased II)
Cimenteng WTP
Kota &
Kab.
New Pipeline
New Pipeline
Old Pipeline
1. Reorganize existing transmission pipelines from Cisangkuy river
At present, raw water from Cisangkuy river transmitted by gravity to WTP
Badaksinga through two transmission pipelines (Pipa Baru and Pipa Lama)
with capasity each 700 lps.
PDAM Bandung proposes to reorganise the water supply system from Sungai
Cisangkuy by changing the existing Pipa Lama transmission pipeline by new
pipe with capasity 1100 lps. This 1.100 lps raw water was planned to be
transmitted to new Water Treatment Plan (WTP) Cimenteng located near the
water source. The existing Pipa Baru would remain unchanged and continue
to deliver water to IPA Badaksinga. The alteration of raw water transmission
system from Cisangkuy river shown in Table 2.
Table 2. Raw Water Transmission System Alteration from Cisangkuy River
Transmission
Pipelines
Year 2008 Year 2010
WTP lps WTP lps
Pipa Baru Badaksinga 700 Badaksinga 700
Pipa Lama Badaksinga 700 Cimenteng 1100
Total 1400 1800
2. Constructing transmission pipeline from Dago Bengkok II
Implementing water transmission system alteration from Cisangkuy river in
2010 would require a replacement water supply for WTP Badaksinga. PDAM
plans to construct transmission pipelines from PLTA Dago Bengkok II to
deliver 600 lps water from Cikapundung river to the current WTP
Badaksinga. In this new water supply scenario, WTP Badaksinga has 100 lps
raw water reduction. Table 3 shown raw water flowrate alteration for WTP
Badaksinga.
Table 3. Raw Water Flowrate Alteration for WTP Badaksinga
Sumber Air Pipa Transmisi Air Baku Maksimum (L/dt)
Tahun 2008 Tahun 2010
S. Cisangkuy Pipa Baru 700 700
Pipa Lama 700 0
S. Cikapundung Cikapundung III 200 200
Dago Bengkok III 0 600
Total 1600 1500
The difference between existing system and the whole proposed development
scenario of Bandung water supply shown in Figure 1.
Fig 1. Exixting and Proposed Development Scenario (PDAM Kota Bandung, 2006)
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RESULTS
Bandung water supply development plan in 2010 will add 1.000 lps raw water.
Total amount of PDAM Bandung raw water shown in Table 4 (highlighted rows
shows the alterations).
Table 4. Total Amount of Raw Water PDAM Bandung
Sumber Air Pipa Transmisi
Tahun 2008 Tahun 2010
Tempat Proses Total Air
(LPS) Tempat Proses
Total Air
(LPS)
S. Cibeureum Cibeureum - IPA Mini
Ledeng
IPA Mini
Ledeng 40
IPA Mini
Ledeng 40
S. Cisangkuy Pipa transmisi lama IPA Badaksinga 700 IPA Cimenteng 1100
Pipa transmisi baru IPA Badaksinga 660 IPA Badaksinga 660
S. Cikapundung
Cikapundung III IPA Badaksinga 180 IPA Badaksinga 180
Dago bengkok III - 0 IPA Badaksinga 600
Cikapundung hulu IPA Dago Pakar 600 IPA Dago Pakar 600
Kolam Pakar PLN IPA Mini Dago
Pakar 40
IPA Mini Dago
Pakar 40
Mata Air Mata air - Ledeng Ledeng 150 Ledeng 150
TOTAL 2370 3370
PDAM allocates 80% lps of additional raw water to improve the quality of its
current service (650 lps for South Bandung and 150 lps for Kabupaten Bandung).
The other 20% (200 lps) allocated for extension area in Gedebage. Table 5 shows
water addition for each service area with several waterloss possibilities.Table 6
shows detailed increasing number of house connection per service zone if assuming
level of waterloss does not change in 2010 (51%). Increasing number of house
connection only occurred in area supplied by WTP Badaksinga and WTP
Cimenteng, which are Karees, Gedebage, Tegalega, and Kabupaten Bandung
(shown in highlighted rows).
Table 5. Water Addition With Several Waterloss For Each Service Area
Wilayah Additional Water With Several Waterloss (lps)
0 51% 60% 40% 20%
Kabupaten Bandung 150 73.5 60 90 120
Gedebage 200 98 80 120 160
Selatan Bandung 650 318.5 260 390 520
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Table 6. Increasing Number of House Connections
Wilayah 2008 2010
Customer Water Usage (m3) Customer Water Usage (m
3)
Bojonagara 21491 460178 21491 460178
Cibeunying 31463 859505 31463 859505
Karees 12418 222355 35470.56 635131
Gedebage 33570 645509 46780.22 899525
Tegalega 27775 408185 55862.4 820961
Ujung Berung 13372 237251 13372 237251
Kabupaten Bandung 440 21094 4413.892 211606
Figure 2 shown existing primary distribution pipelines while simulations with
extension area in 2010 shown in figure 3.
In 2010 simulation, water distribution system is extended to Gedebage service area
and some parts of Southern Bandung. Extension to Gedebage area is done based on
distribution development plan of PDAM. On the other hand, South Bandung service
area also has enough pressure residues on the primary network tip, so that it is
possible to extend distribution network to that part.
Fig 2. Existing Primary Distibution Pipelines
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Fig 3. Primary Distibution Pipelines With Extension in 2010
Simulation result shows that network entension in Gedebage, causing deflation of
pressure residue in some service area. Flow pressure itself is resulted from elevation
difference between highest supply elevations with lowest node elevation, with
respect to pressure loss along delivery process. The deflation of pressure residue in
some primary pipelines end occurred because the increasing discharge of water
flow will also increase flow velocity for the same pipe diameter, then the level of
pressure loss will be inclining altogether. Significant deflation of pressure residue
happened in East Bandung service zone such as Antapani, Kebon Waru, Kebon
Gedang, and Kebon Jayanti.
Very high pressure residue is happen in South Bandung. Extension is made in
Mengger and Margahayu area so pressure in South Bandung is in allowed range.
(Based on PDAM water usage data in 2007 Margahayu and Mengger was an area
with very low percentage of water supply)
One of the aims on increasing production level is to extend service zone. Pressure
residue deflation is lessening the possibility to fulfil the goal, as there is a minimum
value of pressure residue in the end of distribution network. For that reason, to
support the goal of expanding service zone, optimalization and modification on
current network
CONCLUSIONS
Distribution network is extended to Gedebage, Margahayu, and Mengger area.
Gedebage area is chosen since it is allocated by PDAM as new service area (with
new network pipelines). Extension in Margahayu and Mengger is done due to
having enough pressure residue and categorized to be area that has low percebtage
of water supply (based on water usage data of PDAM Kota Bandung on 2007).
Extension in Gedebage causes deflation of pressure residue in some service area.
For that reason, to optimize water distribution, optimalization and modification on
current network is required.
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FURTHERWORKS
Made several adjustments to optimalize water distribution system in Bandung city
especially to manage deflation of pressure residue caused by Gedebage network
extension. Also, different waterloss scenario need to be simulated in 2010: 40%
(PDAM target) and 60% (in case there are waterloss increasing).
References
Babbitt, Harold E., James J. Doland, John L. Cleasby. 1967. Water Supply
Engineering, 6th edition. New York: McGraw-Hill Book Co.
PDAM Kota Bandung. 2006. Corporate Plan 2007-2011.
Rossman, Lewis A., 2000. Epanet 2 Users Manual, United States Environmental
Protection Agency.
Walski, Thomas M., Donald V. C., Dragan A. Savic. 2001. Water Distribution
Modelling. 1st ed. Waterbury: Haedstad Press.
Walski, Thomas M. 1984. Analysis of Water Distribution System. New York : Van
Nostrand Reinhold.