Ded for Pdam Ende

7/22/2019 Ded for Pdam Ende

1/27

Improving Support Needs forUrban Water Supply in NTB andNTT

Detailed Engineering Design for PDAM Ende


2/27

Improving Support Needs for

Urban Water Supply in NTBand NTTDetailed Engineering Design for PDAM Ende

TECHNICAL REPORT

August 2011


3/27

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.


4/27


5/27

i

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


6/27

ii

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


7/27

iii

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


8/27


9/27

DETAIL ENGINEERING DESIGN FOR

PDAM ENDE

Final Report

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.


10/27

2DETAIL ENGINEERING DESIGN FOR

PDAM ENDE

Final Report

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


11/27


PDAM ENDE

Final Report

3

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


12/27


13/27


14/27


PDAM ENDE

Final Report

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.


15/27


PDAM ENDE

Final Report

7

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


16/27


PDAM ENDE

Final Report

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.


17/27


18/27


PDAM ENDE

Final Report

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


19/27


PDAM ENDE

Final Report

11

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


20/27


PDAM ENDE

Final Report

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.


21/27


PDAM ENDE

Final Report

13

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


22/27


PDAM ENDE

Final Report

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


23/27


PDAM ENDE

Final Report

15

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.


24/27


25/27


26/27


PDAM ENDE

Final Report

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


27/27

Ded for Pdam Ende

Documents

Transcript of Ded for Pdam Ende