Study on Economic Partnership Projects. in Developing Countries in FY2007. Study on Construction of Underground Flood Retention. Ponds in DKI Jakarta

Transcription

1 Study on Economic Partnership Projects in Developing Countries in FY2007 Study on Construction of Underground Flood Retention Ponds in DKI Jakarta SUMMARY March 2008 Nippon Koei Co., Ltd. Ebara Corporation

2 Summary S1. Background of the Project and its Necessity S1.1 Background of the Project DKI Jakarta is the capital of Indonesia, having more than 9.0 million of population as of 2005, and the greatest city in Indonesia. The climate is typical tropical rain forest having two seasons of dry and wet in a year. The Gross Regional Domestic Product (GRDP) in DKI Jakarta is so huge as about 17% of GDP of the whole Indonesia. Damages due to inundation by floods frequently occur in DKI Jakarta especially in January and February during the rainy season. The DKI Jakarta suffered from three major floods in 1996, 2002 and 2007 in last 10 years. Among those, the floods in 2002 and 2007 caused serious damages. Therefore, it is necessary to mitigate the frequent damages due to inundation urgently. To cope with this serious issue, a number of plans for flood control and drainage management were prepared in the past. However, most of those planned projects have not been implemented to date. For example, construction of Eastern Banjir Canal (EBC) has been delayed and diversion works from the Ciliwung River to the Cisadane River has not been implemented yet. Major reasons of the delay are difficulties of issues on the land acquisition and resettlement of the residents. S1.2 Necessity of the Project Under the situation, alternative measures to mitigate flood/inundation damages which do not require land acquisition are needed. As one of alternative measures, the construction of underground flood retention pond (UFRP) is considered realistic and effective to achieve the objective. This is the reason why the Project, UFRP, is necessary to mitigate the current flood and inundation damages, which do not require large land acquisition. The realization of the project is required rather urgently. S2. Basic Principle to Determine the Components of the Project S2.1 Policy of the Study The Policy of the Study in respect of the construction of UFRP as an alternative measure to mitigate the flood and inundation damages is to promote the formulation of the Project taking into consideration the followings such as 1) conducting the on-site survey to collect necessary information and data, 2) maintaining consistency with the existing projects to mitigate flood and inundation damages, 3) considering effective use of Japanese high level technology, and 4) undertaking economic evaluation properly.

3 S2.2 Selection of Project Sites Basic conditions to determine the project sites are as follows: 1 The project sites should not require the land acquisition. 2 The project sites should be located in the flood and/or inundation prone areas. 3 The project sites are expected to be economically feasible by mitigation of the flood and inundation damages. Taking into consideration the above and the results of consultation/discussions with the counter-part personnel of Indonesian side, the project sites were selected at such three areas as Monas, Cempaka Putih and Senayan districts. S2.3 Principles for Drainage Plan Design scale of the Project is planned by the 10-year or 25-year probable one-day rainfall in the Jakarta City area in order to harmonize with the Master Plan (M/P) of Drainage Improvement in Jakarta Area established under the JICA Study. The priority areas have been developed and most of the land in these areas is occupied by commercial buildings, houses, and main roads. It therefore, is difficult to identify proper lands for widening of the drainage channel width for the purpose of flow down the flood safely. Under this situation, it is recommended to collect storm-water or floods to underground tunnel floodway and to store it into retention ponds to be constructed under the ground. Finally, the stored water needs to be pumped out to close drainage system from the retention pond, after a flood gradually. S2.4 Proposed Drainage Facilities of the Project The proposed drainage facilities under the aforesaid basic principles for the Project are; 1) intake facilities in order to trap storm-water or flood water, 2) conveyance shield tunnel, 3) underground retention pond, 4) outlet pipeline facilities, 5) pumping station, and 6) power supply system for gates at an intake facilities, garbage trash and removal equipment and pumping equipment. In determination of required scale of facilities, the required volume of UFRP is estimated as the volume of design discharge which exceeds the flow capacity of drainage system. It is also planned to determine a capacity of pump facility which can evacuate the water retained in UFRP within 24 to 48 hours after start of evacuation. S3. Outline of the Proposed Project S3.1 Design Features (1) Monas Area The main conveyance tunnel with a length of 1,163 m and diameter of 0.9 m to 2.7 m is planned to be laid down at the underground of 12 m to 13 m in maximum. Construction method of shield

4 tunneling or pipe-jacking is applied, and vertical shaft for construction works is proposed to be used as a collector of storm-water in the drainage basin. The collected storm-water is conveyed to an underground retention pond with a storage capacity of 49,200 m 3, which has reinforced concrete structure and dimensions of width 46 m x length 116 m x depth 11 m. The stored water is planned to be drained out by pumps with the maximum capacity of 0.57 m 3 /s and through outlet drainage pipeline with a diameter of 0.7 m and length of 750 m. The specifications and main features are listed as follows: Table S3.1 Specifications and Main Features of Proposed Facilities in Monas Area Facilities Specification Main Features 1) Intake Facilities Use of vertical shaft 4 tunnels x dia. 4 mxdepth 15 m 2) Conveyance Tunnel structure by shield tunneling or dia. 0.9 m x 130 m, dia.1.2 m x 260 m, dia.2.7 m x Shield Tunnel pipe-jacking method 773 m 3) Underground Retention Pond Reinforced concrete structure Length 120 m x width 50 m x depth 16 m, including thickness of concrete 4) Pumping Submersible pump Total discharge capacity 0.57 m 3 /s Facilities No. of pumps 2 nos. Discharge capacity 0.29 m 3 /s per a pump Minimum hydraulic head 9 m Total hydraulic head 14 m Revolution of pump 1,490 per min. Capacity of motor 75 kw 5) Outlet Drainage Pre-stressed concrete pipe dia. 0.7 m x 750 m (open-cut method) Pipeline 6) Power Supply Low voltage power supply Pumping station 380 V Pump equipment 300 kva 1) Shield Tunneling Method The method is defined as a tunneling method that executes tunnel excavation with usually circular shape by a shield machine by which tunnel excavation can be made even in a deep soft alluvial ground under groundwater pressure. The shield machine has a laterally placed cylindrical shape which forms a shell to protect the shield machine body from external earth pressure as well as the ground water pressure. The front end of the shield machine is equipped with a cutter-head in which various type of cutter bits are embedded to excavate the ground. The tunnel excavation can be made by rotating the cutter-head. As the permanent ground supporting system of the tunnel, segment rings made of pre-stressed concrete or steel, are installed at the end of the shield machine simultaneously with the progress of the tunnel excavation. The shield machine is progressed forward by hydraulic jacks, which has the support at the front of the segment rings, then the tunnel is constructed. The maximum and minimum sizes of the tunnel excavation diameter are about 14 m and 1.8 m, respectively. 2) The Pipe-jacking Method The method is defined as the tunnel excavation and installation of various pipes and/or pipeline in the underground by using the thrust force of jacks which are set at the bottom of a shaft. First of all, the shaft is constructed as the base of launch. Secondly at the bottom of the shaft the machinery equipment for the tunnel excavation is installed. Thirdly, the excavation machine with which disc-cutters are attached for the excavation is connected with the pipe(s) to be installed in the underground, such as sewage pipes manufactured in a factory. The

5 excavation machine attached with the pipes are penetrated into ground by hydraulic jacks which are installed at the bottom of the shaft, then sewage pipeline or other pipelines are constructed under ground. The pipe jacking method has a limitation of the maximum size due to friction between the pipes and the surrounding ground, and normally the maximum diameter of the pipes is about 3.5 m or less. (2) Cempaka Putih Area The area has suffered from the drainage congestion because of insufficient capacity of the existing drainage channel of Utan Kayu River into which storm-water is not able to join. Therefore, the storm-water needs to be collected by conveyance tunnels under the existing roads along the existing channel and/or in the inundation areas. Because similar inundation has occurred at the joining point with a tributary of this existing drainage channel, an intake facility is provided at this junction in order to trap storm-water over the flow capacity of a tributary channel. The trapped water is stored in the underground retention pond. The underground retention pond with the capacity of 114,000 m 3 shall be constructed by a shield tunneling with a large diameter, since Cempaka Putih area is developed for residential area and wide land for the retention pond is not identified in this area. The pumping station is provided at the downstream end of the tunnel in order to drain out the stored water within 24 hours, taking into account the water level of the existing channel. The specifications and main features are listed as follows: Table S3.2 Specifications and Main Features of Proposed Facilities in Cempaka Putih Area Facilities Specification Main Features 1) Intake Facilities Two intake structures with side overflow type weir at the existing drainage channel East intake(width 38 m x height 3.55 m) West intake(width 20 m x height 4.10 m) Provision of gates and garbage trash and removal equipment at each intake 2) Conveyance Shield Tunnel Shield tunnel dia. 1.0 m x 905 m, dia. 1.1 m x 329 m, dia. 1.2 m x 390 m dia m x 645 m, dia. 1.5 m x 520 m, dia m x 1,094 m, dia. 1.8 m x 410 m dia. 2.4 m x 433 m dia. 2.6 m x 424 m, dia. 2.8 m x 61 m dia. 3.0 m x 946 m Total length of tunnel : 6,157 m Maximum depth : 11 m dia. 10 m x length 1,500 m 3) Underground Shield tunnel Retention Pond 4) Pumping Submersible pump Total discharge capacity 1.32 m 3 /s Facilities No. of pumps 2 nos. Discharge capacity 0.66 m 3 /s Minimum hydraulic head 16 m Total hydraulic head 17 m Revolution of pump 990 per min. Capacity of motor 160 kw 5) Outlet Drainage Pre-stressed concrete pipe dia. 0.6 m x 18 m (open-cut method) Pipeline 6) Power Supply Power supply equipment Intake facility 30 kva x 2 intake structure sites Pumping station 500 kva Electricity receiving facility 380 V x 1 (east intake) 80 V x 1 (west intake) 380 V x 1 (pumping station)

6 (3) Senayan Area This area has suffered from flooding and inundation damages induced by insufficient flow capacity of the Krukut River with a drainage area of 80 km 2. In order to reduce these damages by trapping the flood, it is proposed to provide an intake facility with side over-flow weir at the upstream of inundation area. The trapped flood water is conveyed to the proposed underground retention pond in Senayan Athletic Stadium through conveyance shield tunnel to be constructed under the existing road. The underground retention pond shall be constructed by applying open and cut method and its structure shall be a reinforced concrete type. The storage capacity shall be 1,101,200 m 3. The stored water is drained out through the outlet drainage pipeline, of which a part duplicates the conveyance tunnel, to the existing drainage channel. The pumping station is constructed in the retention pond, and the pumping capacity is determined at ones for discharging the stored water within 48 hours. The specifications and main features are listed as follows: Table S3.3 Specifications and Main Features of Proposed Facilities in Senayan Area Facilities Specification Main Features 1) Intake Facilities An intake structures with side Intake structure (width 15.5 m x height 2.0 m) overflow type weir at the existing Provision of gates and garbage trash and removal drainage channel equipment at each intake 2) Conveyance Shield Tunnel Shield tunnel dia. 3.5 m x length 1,150 m (maximum height: 16 m) 3) Underground Retention Pond 4) Pumping Facilities Reinforced concrete structure Length 550 m x width 150 m x height 23 m 1st stage :length 350 m x width 150 m x height 23 m 2nd stage :length 200 m x width 150 m x height 23 m Submersible pump Total discharge capacity 6.37 m 3 /s No. of pumps 6 nos. Discharge capacity 1.07 m 3 /s per a pump Minimum hydraulic head 12 m Total hydraulic head 14 m Revolution of pump 740 per min. Capacity of motor 220 kw Pre-stressed concrete pipeline dia. 2.4 m x 810 m (open-cut method) 5) Outlet Drainage Pipeline 6) Power Supply Power supply equipment Intake facility Pumping station Receiving facility 60 kva 2,000 kva 380 V x 1 (intake facility) 6.6 kv x 1 (pumping station) S3.2 Project Cost S3.2.1 Estimate conditions of Project Cost (1) Construction Cost It is conceivable that construction materials and labors for the civil works of the Project are basically procured in and around Jakarta in Indonesia. Therefore, the construction costs of the civil works are determined based on those in the previous studies in consideration of price escalation to the year 2007 price level. However, the following three work items will be procured from Japan. As for the item 1) Shield

7 Tunneling and Pipe Jacking method, Japanese advanced technology should be applied to the construction works in order to transfer technology to Indonesia. Therefore, actual construction cost in Japan is principally referred to the cost estimation. A construction cost for underground MRT construction, which has been planned and is currently under design, is also referred to the cost estimation. - Pipe-jacking Method (for Drainage Main Pipe of Monas Scheme: 2.7 m diameter and 780 m long) and Shield Tunneling Method (for Underground Flood Retention Pond of Cempaka Putih Scheme: 10 m diameter and 1.5 km long and for Drainage Main of Senayan Scheme: 3.5 m diameter and 1.2 km long). - Pump Equipment - Cleaning Equipment for Underground Retention Pond and Pipes Exchange rates applied are USD 1 = JPY = Rp..9,118 (average in 2007), thus JPY 1 = Rp (1) Operation and Maintenance Cost is estimated based on construction cost as follows: - For Civil Structures : 0.5% of Civil Works per annum - For Electrical and Mechanical equipment : 2.0% of E&M Works per annum (2) Cost for Engineering Services is also estimated based on construction cost as follows: - Feasibility Study (F/S) : 3% of Construction Cost - Detailed Design and Construction Supervision : 7% of Construction Cost (3) Cost for Project Administration is 1.5% of Construction Cost and Engineering Services Cost. (4) Contingency is 10% of Construction Cost, Engineering Services Cost and Project Administration Cost. (5) Value Added Tax is 10% of Construction Cost, Engineering Services Cost and Project Administration Cost and Contingency. S3.2.2 Total Project Cost From the above conditions, the estimated project costs are as following table:

8 Scheme Construction Cost Table S3.4 Estimated Project Costs Land Acquisition & Compensation Engineering Service Cost Government Administration Cost Contingency (Unit: Rp. billion) Value Added Tax Project Cost Senayan 2, ,097 (for 25-year flood) Senayan 1, ,082 (for 10-year flood) Monas Cempaka Putih 1, ,773 S3.3 Outline of Project Evaluation S3.3.1 Financial Evaluation The objective of the Project is drainage improvement and/or flood mitigation in DKI Jakarta. The drainage improvement and flood mitigation projects are principally not accompanied with income from tariff collection for its services. Therefore, in this Study a quantitative financial evaluation is not carried out. S3.3.2 Economic Evaluation A quantitative economic benefit is normally regarded as Flood Damage Reduction/Mitigation. In this Study, as the flood damage and assets survey has not been carried out, the flood damage is estimated referring to that in previous studies. Among the existing reports and data, Urgent Inventory Study on Damage of Flood 2002 in JABODETABEK Area in Indonesia (2003 JICA Study) was considered to be the most reliable, then it was adopted for this Study. The economic evaluation for this project is made by using the Economic Internal Rate of Return (EIRR). The result of the analysis is shown in the table below: Table S3.5 Results of Economic Evaluation Scheme EIRR (%) B/C at 10% discount rate Senayan (for 25-year flood) Senayan (for 10-year flood) Monas Cempaka Putih From the above table, only Monas area is evaluated to satisfy the discount rate of 10% that is regarded as general evaluation criteria of a project.

9 S3.3.3 Comparison with Alternative Scheme and Reason of Selection for Optimum Scheme It was expected that an alternative scheme to this Project would be a plan of multipurpose underground tunnel which is promoted by the Jakarta Water Supply Regulatory Body as of November The tunnel will be utilized as roadway and waste water drainage in normal condition and floodway in flood condition. The multi-purpose underground tunnel would be beneficial for flood mitigation for most of the areas in and around the Ciliwung-Western Banjir Canal (WBC) system, whilst the Project with UFRP aims at mitigating inundation damages in priority area with relatively limited area. Therefore, beneficiary areas for both projects would be complementary to each other rather than overlapped. This means that the objectives and their effect are different between the two projects. Since it is judged to be not viable to compare the two projects as alternatives each other, the comparison was not made. Accordingly, the selection of the optimum scheme was not made among the alternatives. S3.4 Environmental and Social Effect The Project is expected environmental improvement effect which is mitigation of flood inundation. The mitigation of flood inundation will improve 1) sanitation of inundation area and 2) traffic jam during the floods. After completion of the Project, the scale of 2002 flood damage will be mitigated. Therefore, the environmental improvement by the Project will be very significant. According to preliminary evaluation on the environmental and social effect, the followings are clarified: 1) regarding underground water, UFRPs in Monas and Senayan will possibly affect the groundwater elevation because the elevation of UFRP is located below the groundwater elevation. Hence, impact on the groundwater in Monas and Senayan shall be clarified by EIA quantitatively, 2) regarding disposal of excavated soils, there are no stipulated regulations but contractors are obliged to follow some disposal rules. The dispose of excavated soil is basically carried out inside of the province which means the excavated soil from the UFRP construction sites should be discarded inside DKI Jakarta. DKI Jakarta has determined the criteria for EIA and UKL-UPL (Environmental Management and Environmental Monitoring) in Decree No Year 2001 and Decree No. 189-Year The screening was made for each Project site based on the above criteria. As a result, it is required to conduct EIA at all of the project sites because of the depth of UFRP. S4. Implementation Schedule Since all the three schemes are still not matured even after completion of this Study in order to proceed with the implementation stage, feasibility studies are required to confirm a viability of the Project. It is anticipated that the feasibility studies will be conducted under the JICA Development Study Program and detailed design and construction will be done by applying JBIC Yen Loan. A project implementation schedule is presented as following figure:

10 Items JETRO Study 1.Senayan Scheme F/S: Application/Approval F/S: Undertaking Japanese Loan: Application/Agreement Consultant: Tender/Contract Detail Design Contractor: Selection Construction Works 2.Monas Scheme F/S: Application/Approval F/S: Undertaking Japanese Loan: Application/Agreement Consultant: Tender/Contract Detail Design Contractor: Selection Construction Works 3.Cempaka Putih Scheme F/S: Application/Approval F/S: Undertaking Japanese Loan: Application/Agreement Consultant: Tender/Contract Detail Design Contractor: Selection Construction Works Figure S4.1 Project Implementation Schedule S5. Feasibility related with Request for Japanese Loan and the Implementation The flood and inundation damages currently occur very frequently in DKI Jakarta, and many projects to mitigate the flood and inundation damages proposed in various M/Ps have not been completed or even not commenced yet to date. Under the circumstance, it is needed to take prompt action toward the request and implementation of the Japanese loan, by undertaking confirmation studies (F/S or SAPROF) for the viability of the Project. It is unforeseen whether or not the multi-purpose tunnel project will be implemented shortly. However, taking into consideration the need of urgent realization of the flood damage mitigation projects, the Project, in particular the Monas area, is needed to be implemented from economic, environmental, and humanitarian points of view, possibly by using the Japanese loan. Hence, it is evaluated that the supply of Japanese loan is viable for the Project. S6. Technological Advantages of Japanese Company Technical characteristics of construction of the Underground Flood Retention Ponds (UFRP) and Underground Drainage Pipeline (UDP) proposed in this Study are as follows: (1) The most significant characteristics of the projects for UFRP and UDP are to be able to avoid the problematic land acquisition issues which actually cause the significant delay in the implementation of the various existing projects proposed in the past Master Plans, by

11 maximum utilization of the underground of the public lands. In addition, it will be another advantage that the underground system will contribute to minimize the adverse effect to the traffic on the roads in DKI Jakarta which is suffered seriously from the chronicle traffic jam. (2) The Project areas are composed of soft alluvial ground which requires the state of the art technology for the construction of those facilities/structures. (3) The UFRP in Cempaka Putih is to be constructed with a Shield Tunnel Method having 10 m in diameter. The UDP to the Senayan UFRP is also to be constructed with a Shield Tunnel. Further, the UDP to UFRP in the Monas district will be constructed with either a Shield Tunnel or Pipe-jacking Method. Meanwhile, most of major cities in Japan are developed on the soft alluvial plains along sea shores, and hence the soft lands under the cities are highly utilized as seen in the development in deep soft ground also caused partly by densely populated areas. This has resulted in reduction of capability of rain water penetration into grounds and rain water retention capacity, and the underground retention ponds and drainage pump stations have been provided as measures to mitigate urban flood damages. Japanese construction companies therefore have experienced a lot of large scale underground development and acquired a state of the art technology in construction works in underground. Typical examples are the Kanda-River Underground Retention Facility (Retention volume: 540,000 m 3 ), and the Metropolitan Outer-ring Drain Channel (Retention volume: 670,000 m 3 ). The construction of those underground retention facilities requires the shield tunneling method, and the Japanese companies have a high-level technology in the field of the shield tunneling method, which are recognized world-widely by the professionals of the field. Thus, the capability of international competition of the Japans companies in that technical field is considered to be very high. S7. Realistic Schedule until Completion of the Project and Risks to Prevent Realization S7.1 Practical Schedule for Implementation of the Project A lot of process is required until the completion of the proposed Project. A practical schedule will be as follows: (1) The Project is needed to be listed on the Blue Book of Indonesian Government. (2) Thereafter, Indonesian Government will request for technical cooperation and/or Yen loan to Japanese Government. (3) Additional study or evaluation such as F/S (JICA) and/or SAPROF (JBIC) will be undertaken by the Japanese Authorities/Institutions to ensure the Japanese loan. (4) If the Project is confirmed to be viable, the Exchange of Note (E/N) and Loan Agreement (L/A) will be made. (5) After that, the detailed design, tender, construction and operation & maintenance stages will be followed, and the Project will be completed.

12 S7.2 Risks for Prevention of Realization of the Project (1) Land Availability for Underground Flood Retention Ponds Installation of underground flood retention ponds requires enough open space. The candidate sites of the underground flood retention ponds in this study are located at the public land owned by the government agencies. Therefore, the lands shall be available as construction site. However, detailed study and coordination with related agencies are required before the implementation of the Project, especially at Senayan site because the utilization of the construction site should be permitted by the Ministry of State Secretariat, a large-scale pond would be required for the site, and detailed environmental assessment will be necessary. The above issues will have to be studied in the F/S. (2) Land Acquisition Land acquisition will be required to install intake facilities in Cempaka Putih site and Senayan site taking into account the layout of the existing drainage systems. It might be possible to reduce the area of land acquisition after future review and detailed study on the scale of facilities. The scale and methodology of land acquisition shall be examined in detail to minimize its impact before the implementation of the Project. (3) Coordination with Existing Studies/Projects Coordination with existing studies/projects is required to determine the contents of the Project in each site. In particular, the progress of construction of EBC and rehabilitation of WBC affects the contents of the Project. Therefore, the contents of the Project shall be reviewed and modified if necessary depending on the progress of the on-going projects. It is expected that Senayan scheme among the three project sites will have a role as an alternative countermeasure instead of WBC to some extent. The Senayan scheme shall contribute to reduce the inflow into the existing WBC. As a result, the scheme would have effect to reduce inundation damage in the WBC system as well as increase of flow capacity of the canal by improvement. Runoff and inundation model should be developed for the whole area of WBC system on the condition that the Senayan scheme is implemented in order to quantify the alternative effect of Senayan scheme against the canal improvement project. It is possible to examine how much the inundation area is reduced using the model. However, such model has not been established and it should be developed in the next stage. Therefore, it is assumed that reduction in flood peak discharge is an index to evaluate the effect of mitigation of damage amount to evaluate the alternative effect. For example, the peak probable discharge for 25-year return period would be reduced by the Senayan scheme by maximum 95 m 3 /s, that is, design discharge (135 m 3 s) flow capacity (40 m 3 /s) in the Krukut basin. The reduction of 95 m 3 /s in the peak discharge accounts for about 26% of total amount of shortage in flow capacity (370 m 3 /s) of existing WBC against design discharge with 100-year return period. (4) Economic Feasibility In the economic evaluation, it was only the Monas area which showed relatively high EIRR of more than 10%. This may result in difficulty to realize the supply of Japanese loan for the Project. It

13 is, therefore, advised that the following issues should be reminded so as to ensure the realization of the Japanese loan for the Project. 1) The evaluation of damages are made based on the past study report, in which estimated average damages are utilized for urban and rural areas. If in-depth further analysis is conducted for the evaluation of the damages, the benefit might be increased compared with the existing ones. 2) It would be needed to carry out further screening to find more viable areas for the UFRP Project from the flood and inundation prone areas of 78 locations. 3) The above study should be made in the F/S in near future. By the study, it is expected to build a firm foundation toward realization of the Japanese loan.