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Improving Support Needs forUrban Water Supply in NTB andNTT
Detailed Engineering Design for PDAM Ende
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Improving Support Needs for
Urban Water Supply in NTBand NTTDetailed Engineering Design for PDAM Ende
TECHNICAL REPORT
August 2011
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INDONESIA INFRASTRUCTURE INITIATIVE
This document has been published by the Indonesia Infrastructure Initiative (IndII), an
Australian Government funded project designed to promote economic growth inIndonesia by enhancing the relevance, quality and quantum of infrastructure
investment.
The views expressed in this report do not necessarily reflect the views of the Australia
Indonesia Partnership or the Australian Government. Please direct any comments or
questions to the IndII Director, tel. +62 (21) 230-6063, fax +62 (21) 3190-2994.
Website: www.indii.co.id.
ACKNOWLEDGEMENTS
This report has been prepared by Cardno-CRM Consulting Team who was engaged
under the Indonesia Infrastructure Initiative (IndII), funded by AusAID, as part of the
NTT/NTB Water Governance Project Stage 2Activity 183.
Any errors of fact or interpretation are solely those of the author.
Cardno-CRM Consulting Team
Jakarta, August 2011
IndII 2012
All original intellectual property contained within this document is the property of the Indonesia
Infrastructure Initiative (IndII). It can be used freely without attribution by consultants and IndII partners in
preparing IndII documents, reports designs and plans; it can also be used freely by other agencies or
organisations, provided attribution is given.
Every attempt has been made to ensure that referenced documents within this publication have been
correctly attributed. However, IndII would value being advised of any corrections required, or advice
concerning source documents and/ or updated data.
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TABLE OF CONTENTS
ACRONYMS ................................................................................................................. III
CHAPTER 1: INTRODUCTION......................................................................................... 1
1.1 INSTRUCTION AND OBJECTIVE................................................................ 1
CHAPTER 2: SYSTEM REVIEW ....................................................................................... 2
2.1 CURRENT SUPPLY................................................................................ 2
2.2 INTAKE AND PRODUCTION FACILITIES...................................................... 2
2.2.1 Pre-Sedimentation Tank......................................................... 4
2.2.2 Slow Sand Filter Units ............................................................ 4
2.2.3 Disinfection ........................................................................... 5
2.2.4 Ongoing Project ..................................................................... 5
2.3 SERVICE STORAGE AND DISTRIBUTION..................................................... 5
2.3.1 Service Reservoir ................................................................... 6
2.3.2 Distribution Pumps ................................................................ 6
CHAPTER 3: PROJECTED NEEDS .................................................................................... 7
3.1 DEMAND........................................................................................... 7
3.2 INTAKE AND PRODUCTION FACILITIES...................................................... 7
3.3 SERVICE STORAGE AND DISTRIBUTION..................................................... 8
CHAPTER 4: DESIGN NOTES FOR WTP UPGRADING ...................................................... 94.1 SCOPE OF WORKS............................................................................... 9
4.2 PLANT CAPACITIES.............................................................................. 9
4.3 WATER SOURCE CONSIDERATIONS......................................................... 9
4.4 PRE-SEDIMENTATION........................................................................ 10
4.5 MIXING AND COAGULATION............................................................... 10
4.6 SEDIMENTATION............................................................................... 10
4.7 FILTRATION...................................................................................... 11
4.8 TREATED WATER STORAGE................................................................. 11
4.9 REAGENTS....................................................................................... 124.10 TREATED WATER PUMPING STATION.................................................... 12
CHAPTER 5: FOUNDATION CONSIDERATIONS ............................................................ 13
CHAPTER 6: RSF PLANT OPERATION ........................................................................... 15
CHAPTER 7: FUNDING CONSIDERATIONS ................................................................... 16
CHAPTER 8: CONCLUSIONS ......................................................................................... 17
REFERENCES ............................................................................................................... 18
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LIST OF TABLES
Table 1: Chemical Dosing ........................................................................................... 12
Table 2: Comparison of Weight of Existing and Proposed Structure ............................ 13
LIST OF FIGURES
Figure 1: PDAM off-take weir at Bendung Sokamoki on Wolowana River .....................3
Figure 2: Slow sand filter units .....................................................................................4
Figure 3: Short and medium term demand by source in Ende .......................................7
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ACRONYMS
ADB Asian Development Bank
APBD Anggaran Pendapatan dan Belanja Daerah (Regional or Local Government
Budget for income and Expenditure)
APBN Anggaran Pendapatan dan Belanja Negara (National Budget for Income
and Expenditure)
ASL Above Sea Level
Bappeda Badan Perencanaan dan Pembangunan Daerah (Local Development
Planning Agency)
AusAid Australian Government Overseas Aid Program
BPS Biro Pusat Statistik (Central Statistics Bureau)
Dinas PU Regional Agency for the Public Works Department
DJCK Direktorat Jenderal Cipta Karya (Directorate General of Human
Settlements under the Public Works Department)
DPU Departemen Perkejaan Umum (Public Works Department)
GoI Government of Indonesia
IDR Indonesia Rupiah
INDII Indonesian Infrastructure Initiative
NRW Non-Revenue Water
PDAM Perusahaan Daerah Air Minum (Local Goernment Water Supply
Enterprise)
NTB Nusa Tenggara Timur (Province)
NTU Nephelometric Turbidity Units
NTT Nusa Tenggara Timur (Province)
RSF Rapid sand filter
SIPA Surat Ijin Pengambilan Air (Water Abstraction Permit)
SSF Slow sand filter
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1
CHAPTER 1: INTRODUCTION
CHAPTER 1:INTRODUCTION
1.1 INSTRUCTION AND OBJECTIVE
This is the Final Report of the Cardno-CRM Consulting Team with regard to the
NTT/NTB Water Governance Project Stage 2 Activity 183. It describes the overall
project achievements under this activity. The work has been carried out pursuant to an
instruction from SMEC International. The work forms part of the Indonesian
Infrastructure Initiative (IndII) which is funded by the Australian Government through
AusAid.
The objective of the activity is to provide the PDAMs of Ende, NTT and Dompu, NTB
with procurement documents for capital works which will expand their systems. The
proposed works include the implementation of a conversion of existing slow sand
filters to rapid sand filter operation in Ende and an upgrading of the distribution
network in Dompu.
The NTT/NTB Water Governance project has secured Social Contracts between the
PDAMs, Local Governments (LGs), and the water supply consumer representatives of
the participating LGs. As part of the incentives for achieving the outputs of the social
contracts, IndII has agreed to provide support to the PDAMs and LGs. In the case of
Ende and Dompu that support includes assistance with the design of the water supply
improvements necessary to utilise funds provided for expansion by the LG. The design
assistance is the objective of this consulting assignment.
The report defines the scope of Detailed Engineering Designs for capital works required
for systems expansion in each location. The related tender documents for these works
have been provided separately. It is important to note that the scope of work does not
include consideration of the affordability of such works in terms of increased
operational and loan service costs leading to increases in tariffs.
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CHAPTER 2:SYSTEM REVIEW
2.1 CURRENT SUPPLY
The city of Ende is located on the southern shores of Flores Island in relatively
mountainous terrain. It is some 750 kms east of Denpasar. The current population of
the town is just in excess of 260,000 persons. The town has a broad economic base and
operates as a service centre for the surrounding area. It has no major industry with
fishing, tourism and the Flores University being the significant contributors to the local
economy. The population is growing at a modest rate of 1.15 percent per annum.
PDAM Kelimutu Ende provides water supply services to some 8,089 customers. In
excess of 95 percent of these connections are domestic. The current total production
capacity is around 52 l/sec. This is made up of a main town area supply system of 17
l/sec in a slow sand filter treatment plant and 35 l/sec in five separate small spring
supplied systems.
The major supply system from the Wolowana River was constructed in the mid-1980s.
The original DJCK design report1 indicates that this main town area supply system
originally had a design capacity of 30 l/sec. This applied to the treatment plant and also
the service storage and distribution system.
PDAM have calculated that they need 87 l/sec of production capacity to fully service
the 8,089 customers currently connected to their systems.
PDAM also propose that the expansion works should focus on the main system
supplied from the Wolowana River. The increase of production capacity immediately
required is therefore some 35 l/sec.
The following sections of this report therefore focus on the main town area supply
system from the Wolowana River only.
2.2 INTAKE AND PRODUCTION FACILITIES
The Wolowana River intake and production facilities consist of:
Intake weir
Raw water transmission mains
Pre-sedimentation tank
Slow sand filter beds
Disinfection equipment
1Direktorat Jenderal Cipta Karya: Perencanaan Teknis Sistem Penyediaan Air Bersih Kota Ende1988
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CHAPTER 2: SYSTEM REVIEW
The current draw-off from the Wolowana River is at a diversion weir north of the
treatment plant. The minimum debit in the river was reported by PDAM as 900 l/sec.
The PDAM currently does not have a formal permit for abstraction (SIPA) from the
river. Since the flow in the river is quite substantial and the distance to the searelatively short, consideration of downstream users in any increased abstraction
should not present a problem.
Figure 1: PDAM off-take weir at Bendung Sokamoki on Wolowana River
Note: The PDAM intake pipe is submerged in the irrigation channel and there are sandbags atop
the weir to increase the water level upstream and in the irrigation channel.
Initially the raw water intake was located at Kelurahan Rawarangga (elevation 50.1m)
upstream of current draw off. However, the transmission pipe was laid across the river
without any protection and during the rainy season increasing water levels and high
flow rates caused many pipe breakages. Eventually the transmission pipe was washed
away causing a stoppage of production. PDAM relocated the draw off to the weir at
Bendung Sokomoki (elevation 44.3m). The raw water now flows by gravity through two
parallel pipes 200mm diameter and of length 1.5km. The capacity of each pipe is
around 40 l/s. The transmission pipe has been simply laid inside an irrigation channelfor much of its length.
The quality of water observed at the time of the visit was quite good. It appeared
suitable for discharge direct to the distribution system after disinfection, however
there is no by-pass facility on the slow sand filters.
Although the raw water condition at the time of the visit was quite clear, it can
suddenly change during the rainy season with turbidity becoming much higher (> 50
NTU). Apart from this turbidity problem there are several upstream users of the water.
Community usage for bathing and washing adjacent to the pipe inlet causes detergent
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2.3.1 Service Reservoir
The capacity of the service storage is only 200m3 which is less than 8 percent of Slow
Sand Filter design production rate of 30 l/s. The storage reservoir was built in mid-1980s and consists of two tanks with dimensions width 4m by length 12.5m and depth
2.5m.
2.3.2 Distribution Pumps
The distribution system serviced by the treated water abstracted from the Wolowona
River includes both pumping and gravity feed. The treated water is pumped to the
service reservoir at an elevation of 60m asl located at Jalan Eltari. There are some
tappings for consumers along the pipeline to Reservoir at Jalan Eltari.
The distribution system pumps originally included:
1 Unit Ebara Multi stage Pump coupled with Teco electromotor, with capacity Q=
37.5 l/s and total head H=96m
1 unit Ebara Multi Stage Pump coupled with Dong Feng Diesel Engine (1 unit) with
capacity Q= 37.5 l/s and total head H=96m
Operation of the system was initially by one pump when electricity was available. If no
electricity was available the pump coupled with diesel engine was used. Due to the
efficiency of pump and problems with diesel engine, the pump with diesel engine was
abandoned in 2005 after new Grundfoss pumps (3 no.) provided by AusAid wereinstalled.
The new vertical spindle Grundfoss pump specification is: capacity each pump Q= 17,5
l/s and total head H=96 m. Two pumps are operated with one pump standby. However
at times PDAM operate three pumps together which provides a total capacity 52.5 l/s
through a combination of the Ebara pump 37.5 l/s and one Grundfoss pump 17.5 l/s.
This operational method indicates that the SSF fed system is being operated at above
the initial design level.
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CHAPTER 3: PROJECTED NEEDS
CHAPTER 3:PROJECTED NEEDS
3.1 DEMAND
PDAM Ende assess that the total demand to service existing customers is 87 l/sec.
PDAM has a current formal waiting list of some 1,250 customers. This represents
around 11 l/sec of additional demand assuming a NRW level of 30 percent at around
120 l/cap/day. Therefore to service the existing customers plus the waiting list some 98
l/sec of production or an additional 46 l/sec is required. Since the on-going PU project
will provide an extra 30 l/sec, a possible interim upgrading of the existing Wolowana
treatment plant for the short term might add around 16 l/sec capacity bringing it to 33
l/sec.
Figure 3: Short and medium term demand by source in Ende
The draft Business Plan, which was prepared with assistance from IndII, indicates that
the PDAM wish to add a further 10,000 connections in the five year period to 2016.
This would double the size of the existing operation and represents around 83 l/sec of
additional demand, assuming an improved NRW level of 20 percent. Taking the on-going PU project and improved NRW into account, the upgrading of the existing
Wolowana SSF treatment plant for the medium term should provide an overall
capacity of around 100 l/sec in order to service the Business Plan.
3.2 INTAKE AND PRODUCTION FACILITIES
The first requirement for the medium term expansion is provision of an additional raw
water transmission main. This would deliver an additional 50 l/sec by gravity to the
0
20
40
60
80
100
120
140
160
180
Short term Medium term
Springs
PU addition 2011
Main WTP
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treatment plant. At the meeting on 3 August 2011, the PDAM expressed a wish that a
new intake be constructed some 6.5 km upstream of the existing treatment facilities.
It appears, from the above demand analysis that a conversion of the existing slow sandfilter treatment plant to conventional rapid gravity sand filter operation should provide
a new plant with a total capacity of in the order of 100 l/sec.
From a site constraint viewpoint, it appears that the major area of vacant land still
available at the site will be occupied by the new 30 l/sec treatment plant being
provided by Dinas PU. Discussions with PDAM have confirmed that they wish any
upgrading of the slow sand filter plant should be accommodated within the existing
structures.
The consultants assessed that a conversion of one of the existing tanks will provide
sufficient additional treatment capacity for the medium term. A longitudinal division ofthe converted tank is also proposed so that two units of nominal capacity 50 l/sec can
be constructed.
The plant is proposed to include chemical dosing, mixing, clarification in hopper
bottomed units fitted with lamellar plates and conventional rapid gravity sand filters.
A new pump house and associated facilities will be required to accommodate the
increased production capacity.
The consultant also proposes that a by-pass be provided to the plant for periods when
the raw water quality is such that it requires chlorination only.
3.3 SERVICE STORAGE AND DISTRIBUTION
The Wolowana system was designed to provide 30 l/sec to the main area of the town.
The current service reservoir capacity of 200m3is grossly inadequate. A total capacity
of 1,800m3is recommended.
Since only one of the existing slow sand filters is needed for conversion for the medium
term, it is proposed that the second be converted for use as a clearwater tank/service
reservoir. This would provide an additional 900m3
of service storage capacity.
Clearly, since the original distribution system was designed to provide 30 l/sec
capacity, considerable upgrading will be required to accommodate the proposed
expansion of production facilities. A full evaluation of the scope of upgrading required
is beyond the scope of work for this project.
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4.4 PRE-SEDIMENTATION
It is proposed that the existing pre-sedimentation tank shall continue to be used.
Detailed data on this existing tank is as follows:
Dimensions 16.75 x 8 m
Water depth 3 m
Volume 402 m3
Detention time 60 minutes
During periods when the raw water turbidity is low, raw water may be either passed
directly to the RSF or if the quality permits it may be passed directly to disinfection
facility and the clearwater storage tank, proposed to be provided by conversion of the
second SSF unit.
4.5 MIXING AND COAGULATION
The mixing and coagulation tank shall be designed for a raw water flow of 110 l/s with
2 compartments @ 55l/s capacity (198m3/hr). Their characteristics are as follows:
Detention time 20 minutes @ 198 m3/hr
Minimum Volume 1/3x198 = 66 m3
Dimension 7 x 4 m
Water height 2.5 m
Volume 70 m3
4.6 SEDIMENTATION
The plant shall include two Sedimentation Tanks with lamella/plate settlers. Each
sedimentation tank shall be sized and designed to treat half nominal input i.e. 55 l/s
(198 m3/hr). Their characteristics are as follows:
Surface loading 5.65 m3/m2/hr
Minimum area 198/5.65 = 35 m2
Total area 35 m2
Dimensions 7 x 5 m
Water height 2.5 m
Volume 87.5 m3
Retention time 135 minutes
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CHAPTER 4: DESIGN NOTES FOR WTP
UPGRADING
Lamella plate/tube settler:
Hexagonal tube settler (2 inch/50 mm, =60) preferable since higher efficiency
compared to plate settler
Sludge extraction larger diameter pipe to permit higher desludging rate (up to 10
percent)
4.7 FILTRATION
Each sedimentation tank (198 m3/hr) will be served by 2 Filters (99 m3/hr), and shall
have characteristic as follows:
Filtration velocity 3.5 m3/m2/hr
Surface area 99/3.5 = 28 m2
Dimension 7x 4m
Back wash water flow 198 m3/h (7m3/h/m2)
Backwash air flow 396 m3/h (14 m3/h/m2)
Depth of sand/gravel 1 m
Sand effective size 0.9- 1.0 mm
The backwashing equipment shall include:
Two backwash pumps (one as stand by)
Two air blowers (one as standby)
4.8 TREATED WATER STORAGE
Reservoir converted from unit SSF Additional Reservoir converted from existing SSF
with dimension as follows:
Dimension 24 x 15 m
Total area 360 m2
Water height 2 m
Volume 720 m3
Retention time 720/(2x198)x60 = 110 minutes
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4.9 REAGENTS
The storage space of all reagents shall be designed for capacity of 110 l/s. For each
reagent, 2 preparation tanks (24 h retention time) shall be provided. Preparation tanks
and dosing pumps shall be sized on the following basis of 110 l/s capacity.
Table 1: Chemical Dosing
ChemicalMaximumdosage
Consumptionkg/hr
Concentrationsolution
g/l
Outputl/h
TankVolume
m3
Alum Sulphate 50 19.8 150 130 3.2
SodiumHypochlorite
3 1.2 150 8 0.2
4.10 TREATED WATER PUMPING STATION
The treated water shall be pumped up to the Eltari Reservoir located at elevation + 60
m. 3 no pumps of 50 l/s head 92 m capacity each, shall be installed with two operation
and one standby.
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CHAPTER 5: FOUNDATION CONSIDERATIONS
CHAPTER 5: FOUNDATION CONSIDERATIONS
As outlined above, the RSF plant will simply be constructed within an existing SSF
which, for the present, continues to be operated. As such it was not possible to test
the foundations underneath the tank in order to check for any possible settlement
problems.
In addition soil test results were sought from the Provincial Dinas PU who are
constructing a new plant adjacent to the existing SSF plant. No soil test results are
available.
The area of Ende is strongly influenced by volcanic activity (Ref 1). The town area is
quite hilly with rock outcropping in many locations. The immediate area around the
Wolowona River is a mixture of extrusive and intrusive rocks, especially alkaline
Andesite lava and volcanic breccia of a young age. The foundation under the existing
tanks is therefore reasonably solid and possibly rock.
For the purpose of comparison we have computed the total weight of the existing
single SSF and the weight of the new RSF which will be constructed inside the existing
tank.
Table 2: Comparison of Weight of Existing and Proposed Structure
ITEM
DIMENSIONS (M) WEIGHTS (KGS)
Length Width Height Water Floor Wall Sand Total
SLOW SANDFILTER
26 14 3 1,065,435 266,359 177,525 1,278,522 2,787,841
RAPID SANDFILTER
Flocculator 15 4 2 80,475 134,125 36,274 0 250,874
Tube Settler 15 6 3 226,563 110,692 206,280 0 543,534
Filter 6 15 3 217,500 65,250 93,012 184,440 560,202
Filtrate Sump 2 15 3 72,500 20,010 105,156 0 197,666
Pump house 6 15 3 0 87,000 65,250 152,250
SSF box 266,359 177,525 443,884
TOTALS 597,038 683,436 683,497 184,440 2,148,411
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Notes:
1. Assumptions for Specific Gravity: Sand and rock 1,800 kg/m3, Concrete 2,500 kg/m3.
2. Wall thickness for all concrete structures is 300 mm
Based on the above calculation the new RSF will apply a lesser load on the foundation
and therefore it may be expected that no settlement problems will be encountered.
However, it is recommended that the civil works contract include site investigation
work prior to commencement of construction. The minimum bearing capacity
required would be:
2,148,411 kg/(26 x 14) sq m= 5.9 tonne per sq m
FOS 1.5 x 5.9 = 8.9 tonne per sq m
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CHAPTER 6: RSF PLANT OPERATION
CHAPTER 6:RSF PLANT OPERATION
Included as Annex A to this report are a series of Standard Operating Procedure sheets.
These will need to be supplemented with data and information which will be provided
by the successful bidder for supply of the plant and equipment.
In addition to the above it is recommended that consideration be given by IndII to
providing further assistance at the time of startup and commissioning the new RSF
plant. This might be in the form of hands-on operator training.
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REFERENCES
1. DJCK Perencanaan Teknis Sistem Penyediaan Air Bersih Kota Ende 1988
2. Peraturan Menteri Pekerjaan Umum No. 18/PRT/M/2007, DGCK, Dep.PU, 6 June
2007
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