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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)inimier@yahoo.com,

2)iqbal.rofiq@gmail.com

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.