VOLUME 4faspselib.denr.gov.ph/sites/default/files... · TA No. 7258-PHI: Agusan River Basin Integrated Water Resources Management Project – FR – Vol. 4 FINAL REPORT Pöyry IDP

TA No. 7258-PHI: Agusan River Basin Integrated Water Resources Management Project – FR – Vol. 4

FINAL REPORT

Pöyry IDP Consult, Inc.

In association with

Nippon Koei, U.K. Schema Konsult, Inc.

Asian Development Bank

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ADB TA 7258 - PHI Agusan River Basin Integrated Water Resources Management Project VOLUME 4 SUPPORTING REPORTS: INFRASTRUCTURE DEVELOPMENT

JANUARY 2011

Department of Environment and Natural Resources


This report consists of 8 volumes:

Volume 1 Main Report

Volume 2 Report and Recommendation of the President, and Project Administration Manual

Volume 3 Supporting Reports: Watershed Rehabilitation, Biodiversity Conservation, and Related Social and Indigenous Peoples Development

Volume 4 Supporting Reports: Infrastructure Development

Volume 5 Supporting Reports: Institutional Development, Capacity Building, Financial Management Assessment, and Financial and Economic Analyses

Volume 6 Supporting Reports: Safeguards

Volume 7 Supporting Reports: Field Surveys (CD softcopy only)

Volume 8 Supporting Reports: Stakeholder Consultations (CD softcopy only)


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AGUSAN RIVER BASIN INTEGRATED WATER RESOURCES MANAGEMENT PROJECT PPTA

TA NO. 7258-PHI

FINAL REPORT

VOLUME 4: SUPPORTING REPORTS - INFRASTRUCTURE DEVELOPMENT

List of Contents Page Glossary and Abbreviations ii Location Maps vii 1. Butuan City Drainage Subproject 2. Improvement of Municipal Water Supply Systems 3. Upgrading of Hydrological Monitoring Network and Database 4. Upgrading of Regional Water Quality Laboratory Facilities


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GLOSSARY AND ABBREVIATIONS

AD ancestral domain A&D alienable and disposable (land) ADD average daily demand (water supply) ADB Asian Development Bank ADSDPP Ancestral Domain Sustainable Development Protection Plan AIFC average incremental financial cost amsl above mean sea level AMWS Agusan Marsh Wildlife Sanctuary ANR assisted natural regeneration AP affected person APIS annual poverty indicator survey ARB Agusan River Basin barangay village/ neighborhood administrative unit BDC barangay development council BDP barangay development plan BLGU barangay local government unit BNA basic needs approach BOD biological oxygen demand BOT build-operate-transfer BRS Bureau of Research and Standards (of DRWH) BWSA Barangay Water and Sanitation Association CADC certificate of ancestral domain claim CADT certificate of ancestral domain title CBD central business district CBFM community-based forestry management CBFMA community-based forestry management agreement CBMS community-based monitoring system CBO community-based organization CDA Cooperatives Development Authority CDO community development officer CENRO community environmental and natural resources officer CEPA community education and public awareness CIP carbon-in-pulp processing, community irrigation project CLGU city local government unit CLUP comprehensive land use plan CO community organizing COA Commission On Audit COD chemical oxygen demand CPC certificate of public convenience CY calendar year DA Department of Agriculture DAO DENR Administrative Order DAR Department of Agrarian Reform DBL design-build-lease DBO design-build-operate DBM Department of Budget and Management DBP Development Bank of The Philippines DCC Disaster Coordinating Council DECS Department of Education, Culture and Sports DED detailed engineering design DENR Department of Environment and Natural Resources DILG Department of Interior and Local Government DOF Department of Finance DOH Department of Health DPWH Department of Public Works and Highways


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DRA demand responsive approach DRM disaster risk management DRRM disaster risk reduction and management DSA delineated service area DSCR debt service coverage ratio DSWD Department of Social Welfare and Development DTI-BOI Department of Trade and Industry – Board of Investment EA executing agency EARF environmental assessment review framework ECC environmental clearance certificate EIA environmental impact assessment EIRR economic internal rate of return EMB environmental management bureau EMP environmental management plan EMS environmental management system ENR environment and natural resources EO executive order EOCC economic opportunity cost of capital FGD focus group discussion FLUP forest land use plan FMAQ financial management assessment questionnaire forex foreign exchange FPIC free prior informed consent FS feasibility study FY fiscal year (1 January – 31 December) GAD gender action development GADCC gender action development coordinating committee GEF Global Environmental Facility GFI government financial institution GIS geographic information system GOCC government owned and controlled corporation GOP Government of the Republic of the Philippines GR (i) government regulation, (ii) general record (in legal cases) HDI Human Development Index HH household HRD human resources development IA implementing agency IBRD International Bank for Reconstruction and Development (World

Bank) ICC Investment Coordination Committee (NEDA) ICG internal cash generation IDAP institutional development action plan IDC interest during construction IDCB institutional development and capacity building IEC information-education-communication IEE initial environmental examination IFMA integrated forest management agreement IP indigenous people/person IPDP indigenous peoples’ development plan IPO indigenous people organization IPRA Indigenous People’s Rights Act IRA internal revenue allotment IRR implementing rules and regulations ISF integrated social forestry (program) IT information technology


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JICA Japan International Cooperation Agency JSF Japan Special Fund KABP knowledge-attitudes-behavior-practices KBA key biodiversity area KFP an adaptation of KAP (knowledge, attitudes and practices) LDCC local development coordinating council LG local government LGC local government code LGU local government unit LIDAP local institutional development action plan LIHH low income household LLI local level institutions LOI letter of intent l/s liters per second lumad refers to non-Islamized indigenous peoples of Mindanao LWUA Local Water Utilities Administration MAO municipal agriculture office (of DA) MDFO Municipal Development Fund Office MDG Millennium Development Goals M&E monitoring and evaluation MENRO municipal environment and natural resources office, part of LGU MFF Multitranche Financing Facility (ADB) MGB Mines and Geosciences Bureau MHO municipal health office minahang bayan communal mining area MIS management information system MLGU municipal local government unit MMT multi-sectoral monitoring team MOA memorandum of agreement MORO municipal agrarian reform office (of DAR) MOU memorandum of understanding MPA methodology for participatory assessments MPDO municipal planning and development office MRF materials recovery facility masl metrers above sea level MSU Mindanao State University MTPDP Medium Term Philippine Development Plan MTPIP Medium-Term Public Investment Program NAMRIA National Mapping and Resources Inventory Authority NAPC National Anti Poverty Commission NCIP National Commission on Indigenous Peoples NEDA National Economic Development Authority NGA national government agency NGO non-government organization NIA National Irrigation Administration NIMBY not-in-my-backyard NLA national line agencies NPC National Power Corporation NPK nitrogrn, phosphorus, potassium (fertilizer) NPV net present value NRW non-revenue water NSCB National Statistical Coordination Board NSO National Statistics Office NSWMC National Solid Waste Management Commission NWRB National Water Resources Board


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OCD Office of Civil Defense (under Department of National Defense) OCR Ordinary Capital Resources (ADB) ODA official development assistance OJT on-the-job training O&M operation and maintenance PA protected area PAGASA Philippine Atmospheric, Geophysical and Astronomical Services

Administration PAGRO provincial agriculturist office PAM project administration manual (ADB) PAMB Protected Area Management Board PASu protected area superindentant PAWB Parks and Wildlife Bureau PD presidential decree PENRO Provincial Environment and Natural Resources Office (of DENR) PENRO-LGU Provincial Environment and Natural Resources Office (of LGU) PET polyethylene terephthalate (type of plastic) PFI private funding institution PHO provincial health office PIR poverty impact ratio PIU project implementation unit PL protected landscape PLGU provincial local government unit PMDC Philippine Mining Development Corporation PMO project management office PMU project management unit PO people organization, purchase order PPDO provincial planning and development office PPMS project performance management system PPTA project preparation technical assistance PSA poverty and social assessment PSP private sector participation PWSSR Philippine Water Supply Sector Roadmap QA quality assurance QC quality control QM quality management RA republic act RBO river basin organization R&D research and devvelopment RDCC regional development coordinating council RED regional executive director (DENR) RG regional government RIAP revenue improvement action plan RIS regional/river irrigation system RO regional office ROC resolution of consent (of affected persons) RRP report and recommendation of the president (ADB) RWSA Rural Waterworks and Sanitation Association SES socioeconomic survey SD social development SLA sub-loan agreement/ subsidiary loan agreement SMR self monitoring report (water quality) SP sangguniang panlalawigan (provincial legislature) SWM solid waste management


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TA technical assistance TESDA Technical Education and Skills Development Authority TLA timber licensing agreement TNA training needs assessment TOR terms of reference TOT training-of-trainers TWG technical working group UDP upland development program UFW unaccounted-for water UNCBD United Nations Convention on Conservation of Biological Diversity UNCCD United Nations Convention to Combat Desertification UNFCCC United Nations Framework Convention on Climate Change UNICEF USAID

United Nations Children Fund United States Agency for International Development

V variation (to contract with ADB) WASCO Water Supply Coordination Office (NAPC) WD water district WHO World Health Organization WMU watershed management unit WPEP Water Supply and Sanitation Performance Enhancement Project WQ water quality WS water supply WSP water service provider WSP-EAP Water and Sanitation Program – East Asia Pacific WSS water supply and sanitation WTP willingness-to-pay


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Location Map


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Map of Agusan River Basin

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1. BUTUAN CITY DRAINAGE SUBPROJECT

Contents

1 Butuan City Drainage Subproject............................................................................ 1

1.1 Introduction/ Rationale ....................................................................................... 1 1.2 Key Findings of Socioeconomic Survey in Butuan City ...................................... 6 1.3 Existing Drainage System/ Facilities................................................................... 7

1.3.1 Existing Creeks/Waterways ........................................................................ 8 1.3.2 Urban Drainage System............................................................................ 10

1.4 Study Approach and Methodology ................................................................... 12

1.4.1 Introduction ............................................................................................... 12 1.4.2 Assessment of Existing Drainage Situation ............................................... 12 1.4.3 Field Survey and Investigation .................................................................. 12 1.4.4 Engineering Investigations ........................................................................ 13 1.4.5 Formulation of the Updated Drainage Master Plan ................................... 14 1.4.6 Consultations with Stakeholders ............................................................... 14 1.4.7 Details of Engineering Analyses ............................................................... 14

1.5 Scope for Drainage Improvements under Updated Master Plan ....................... 17 1.6 Proposed Subproject Scope (Phase 1) ............................................................ 18 1.7 Stakeholder Consultation Workshop ................................................................ 20 1.8 Estimated Subproject Impact and Outcome ..................................................... 22 1.9 Estimated Investment Cost .............................................................................. 22 1.10 Implementation Schedule and Contract Packaging .......................................... 23 1.11 Subproject Actors and Their Responsibilities ................................................... 25 1.12 Sewage Treatment ........................................................................................... 25 1.13 Recommendations ........................................................................................... 26

1.13.1 Immediate/Short-term Strategies for Maintenance of Drains ..................... 26 1.13.2 Implementation of Long-Term Measures .................................................. 26

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Figures 1.1 Location of Butuan City on Agusan River Delta 2 1.2 Area Prone to Flooding – Butuan City 3 1.3 River and Natural Drainage Network of Butuan City (West Bank of Agusan River) 9 1.4 Existing Urban Drainage System in Butuan Central Business District 11 1.5 10-year Rainfall-Intensity-Duration-Curve for Butuan City 16 1.6 Proposed Butuan City Improved Drainage Works (Phase 1) 19 1.7 Proposed Implementation Schedule (Phase 1) 24 Tables 1.1 Key Findings of Socioeconomic Survey 6 1.2 Proposed Butuan City Drainage Works (Phase 1) 18 1.3 Butuan City Drainage Cost Estimate (Phase 1) 23 1.4 Contract Packaging for Butuan Drainage Phase 1 25 Appendices 29 1.1 Photographs of Existing Drainage System in Butuan City 30 1.2 Field Survey and Investigation Report and Map 32 1.3 Scope and Cost Estimate of Interventions under Updated Butuan

City Drainage Master Plan (Phases 1 to 3) 48 1.4 Survey Requirements for Detailed Engineering Design 49 1.5 Butuan City Sewage Management and Treatment Options for the Central Business District – Framework for Sewerage Planning 51

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1 BUTUAN CITY DRAINAGE SUBPROJECT

1.1 INTRODUCTION/ RATIONALE

1. Butuan City is located on both banks of the Agusan River (Figure 1.1). However, the city proper (central business and densely developed areas) is located on the west bank. Due to the city’s location on the delta, it is traversed by a series of relatively small natural creeks on either banks of the river.

2. Butuan City was previously the administrative capital of Agusan del Norte. The City is located on the delta of the Agusan River which has a total catchment area of 11,700 km2. The physical topography of the area where the city is located is generally flat with ground elevations ranging between 1.5 to 3.0 m (above mean sea level).

3. By virtue of the city’s location in the Agusan River delta, the area is naturally prone to regular flooding by Agusan River overbank flows. The City’s drainage system is also affected by backwater effects from Agusan River and tides from Butuan Bay. Tidal and backwater effects on the city’s drainage channels exacerbate flooding and compound the drainage problems faced by the city.

4. Butuan City, with 27 barangays and a population of 298,378 in 2007, has more than doubled since its population of 131,094 in 1970. The urban population in 2007 was 92,556. Urban areas are along a major river/creek network. The population continues to grow fast as mangroves and flood plains towards the coast convert to residential and commercial areas. This is seen in the correspondence of identified flooded zones on both sides of the river as shown in Figure 1.2. Ocular inspection indicates the possible need for relocation.1

5. From discussions with the Butuan City government, including the newly-elected mayor, improvements to the city drainage is a high priority in the development plans of the city, and a flood control and drainage task force has been formed.

1 City Planning & Dev't. Office / NSO - XIII, Butuan City.

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Figure 1.1: Location of Butuan City on Agusan River Delta

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Figure 1.2: Area Prone to Flooding – Butuan City

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6. Lower Agusan Development Project. To mitigate the effect of regional flooding from Agusan River and to improve the overall drainage of the river/creek systems in Butuan City, the Lower Agusan Development Project (LADP), which involved a series of studies and stages/phases, was implemented. The following were carried out under the LADP:

LADP: Feasibility Study and Report, June 1981. LADP: Review Report, Annex I- Hydrology; Annex III-Flood Control, January 1983. LADP: Design Report, Volume I, Flood Control, October 1981. LADP-I: Preliminary Study on Drainage System in West Bank of Butuan City, April

1992. LADP-II: Updated Design for the LADP, Stage I, Phase II, February 1999.

7. The Lower Agusan Development Project (LADP-II), Stage I, Phase II was implemented by the Department of Public Works and Highways (DPWH) through the Project Management Office of the Cotabato-Agusan River Basin Development Project (PMO-CARBDP). The LADP-II comprised four packages:

Package I: Agusan River improvement (east bank) and cut-off channel. Package II: Construction of Magsaysay Viaduct. Package III: Improvement of Banza River and land improvement. Package IV: Masao River improvement and construction of urban drainage system in

Butuan City. 8. Packages II and IV related to drainage improvements on the west bank of Agusan River where the main city is located. Package II comprised the construction of an earth levee and a concrete floodwall along the west bank of the Agusan River to protect the city from Agusan River floods. Package IV involved improvements to the Masao River and the main urban drainage creeks/rivers on the west bank. Although most of the works under the above four packages have been implemented, the construction of an earth levee (1.6 km) from Mangangue Creek to Agusan Pequeno River and channel improvements along Langihan Creek have not yet been completed.

9. It has been confirmed by the city government that since the construction of the levees and floodwalls, Butuan City has so far been spared from Agusan River flooding. As mentioned above, the focus of Package IV was to improve overall local drainage on the west bank of Agusan River by improving flow capacity and conveyance by creeks and other major waterways draining the city. Although improvements made to increase the discharge capacity and efficiency of the waterways have overall resulted in the reduction of the level of local flooding, problems still arise within the city’s urban drainage system for various reasons as mentioned below. 10. Factors contributing to flooding. The flooding/drainage problems faced by the City may be attributed natural and man-made factors as indicated below.

Physical nature of the flood-prone areas; these areas are mainly flat, low-lying and difficult for natural drainage.

Significant amount of stormwater runoff from the western highlands, contributing to flash floods.

High elevation of the groundwater table resulting in saturated soils and less absorption of rainfall on the ground, thus contributing to higher runoff.

Increase in stormwater runoff due to increasing urbanization. Backwater and tidal effects from Agusan River and Butuan Bay controls outflows from

the city’s drainage systems. Absence of drainage infrastructure in some areas to convey and discharge flows. Insufficient flow capacity of the existing urban drainage infrastructure to cope with

increasing stormwater runoff.

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Insufficient number and capacity of stormwater inlets (catch basins) to capture flows into the piped or covered drainage systems.

Obstruction of natural drainage flow paths and building encroachment on channels. Filling-in and replacing open channels along city roads with under-sized

pipes/culverts in order to provide parking areas and walkways along shop-fronts. Lack of implementation of vertical controls of finished surface/ground levels to ensure

proper drainage of urban developments in low-lying areas. Lack of maintenance of the existing drainage infrastructure. Acm3ulation of solid waste and sediment in drains, in addition to overgrown

vegetation, not only impedes flows but reduces the flow-carrying capacity of the drains.

Lack of proper planning and policy/regulation enforcements to fully address the drainage problems in a holistic way.

11. Although flooding in the city streets does not cause serious damage to goods and property, the floodwaters pose health risks (as the floodwater is mixed with sewage) and interrupts daily livelihood activities.

12. Currently, except for drains along the National Highway, which is under the jurisdiction of DPWH, the city government is responsible for all other remaining drains within the city precincts. In order to alleviate flooding within city streets, the city government and DPWH have taken piecemeal approaches to improving drainage. As the city is served by a network of roadside drains which discharge into a complex system of creeks/rivers, and which all interact together, an integrated approach to solving the drainage problem is therefore required.

13. It should be noted that the Lower Agusan Development Project focused on regional flooding from the Agusan River and flooding caused by overbank flows from the natural/major waterways in Butuan City.

14. Master Plan. In order to solve the flooding and drainage problems associated with local stormwater runoff within Butuan City, a drainage master plan was prepared by the city government in November 2003. The drainage master plan covered 39 urban barangay of the city. The total cost of implementing the works was estimated at P686.8 million (in 2003 monetary figures) with the city’s urban drainage system accounting for P382.8 million and P304 million for flood control works. The drainage master plan for the whole works was intended to be implemented over a 10-year period.

15. A lot has changed in terms of the city’s development (physical environment) and implementation of some drainage improvement works since the preparation of the drainage master plan by the city. In view of these, and to reflect the present and anticipated future catchment and drainage conditions of the city, it is necessary to update the 2003 Drainage Master Plan prepared by the City LGU.

16. Proposed subproject. An overall drainage strategy/plan adopting an integrated approach to solving the city’s drainage problems and improving institutional capacity of Butuan City Government to efficiently operate and maintain the drainage infrastructure is therefore the subject of this Updated Butuan City Drainage Master Plan. This perception was echoed when the Butuan City Drainage Subproject was accorded high priority by stakeholders at the Inception Workshop held in Davao City in March 2010 organized by the Consultant to discuss and shortlist potential subprojects for the ARBIWRMP.

17. The goal of the Butuan City Drainage Subproject, if implemented, will be the improvement in living conditions of local residents through thre minimization of the adverse socio-economic impacts attributed to poor drainage and flooding in the city. Specific

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economic benefits to be accrued from the Butuan Drainage Subproject are outlined in Volume 7, Chapter C.

1.2 KEY FINDINGS OF SOCIOECONOMIC SURVEY IN BUTUAN CITY

18. The study focused on Butuan City households’ experience of flooding, and consisted of 271 HH interviews in selected urban and rural barangay, as well as 50 commercial/business establishments and institutions in the city.

19. The evaluation of flood damages consisted of direct damage to public and private properties as a consequence of floods; these are damages to households, commercial establishments, agricultural crops, infrastructure and utilities. Indirect damages included the reduction of the income of wage earners, business concerns and farmers as a result of floods.

20. The HH survey was conducted in the following barangay of Butuan City: Brgy. Agao, Brgy. Baan Riverside, Brgy. Bayanihan and Brgy. J.P. Rizal, categorized as urban barangay; Brgy. Maon and Brgy. New Society, categorized as rural barangay. These barangay were purposively chosen based on their proximity to the Agusan River as well as having the highest population. The 271 sample respondents were proportionally allocated to each barangay. The 50 commercial and business establishments were purposively chosen in the commercial center of Butuan City.

21. Key findings of the survey are summarized in Table 1.1.

Table 1.1: Key Findings of Socio-Economic Survey Parameter Component Survey Result

Population Characteristics

Poverty Threshold Monthly Household Income for Water Supply P 6,195 for a family of 5 based on the NSCB (National Statistical Coordination Board) Official Poverty Statistics published on June 2007

Average Monthly HH Income = P9,329.54

Average Number of Persons Living in the HH: 6 persons

Average monthly water bill:

House ownership: 90% owners

Ethnic Affiliation: non-indigenous peoples – 94.8%.

Needs and Demands

Water Main source of water: piped connection – 87.5%; non-piped connection – 12.5%

Sanitation

Affordability and Willingness to Pay

Water Sanitation

Hygiene and Sanitation

Water and Sanitation

Toilet facility: Water-sealed (flush of pourflush) connected to septic tank. (85.2%).

Top three identified hygiene and sanitation problems in the community are exposed drainage system (21%), no/irregular garbage collection (20.7%) and flies.

Solid Waste Management

Awareness on RA 9003: partly aware (58.3%); fully aware (14.4%); No idea - 27.3%.

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Parameter Component Survey Result

Drainage Experience of Flooding: HHs: 69% experienced flooding; Commercial: 82%.

Use of Drainage Facility: HHs: discharge of rainwater as the predominant purpose for the drainage facility; discharge of wastewater from toilet and the kitchen; discharge of solid waste; Commercial:

Causes of Flood: HHs: nonavailabilty of drainage, inadequacy of drainage, blocked drainage and partially blocked drainage appear as common causes; Heavy rains; Commercial: clogged drainage system due to garbage; drainage is not available, heavy rains, drainage is inadequate, drainage is fully blocked and drainage is partially blocked.

Top issue on drainage of nearby establishment: no proper drainage for the drains of nearby establishments.

Treatment of sewage in businesses: 82% have a septic tank in their property; 6% has a small sewage treatment plant (STP) in their property; 6% have a facility on another property.

Need for a combined drainage and sewerage scheme: 70% of respondents rated the need for a combined drainage and sewerage scheme as important.

Willingness to see improvement in sewage disposal: 68% of the respondents are willing to see improvement in sewage disposal.

Social Organization, Gender Roles, Issues

Gender and Development

Membership in organization: 60% of are not members of association or organization in the community; 36.2% claim to have some form of social networks.

Aspirations. Top three aspirations are having improved job opportunities (31%), for children to be able to finish college (17.7%) and development in the barangay (9.6%) and other aspirations like family planning, eating three times a day, owning house and lot” (9.6%).

% of HHs headed by women: 24.7%

Top 3 issues of women: Unemployment (25.5%), early pregnancy and early marriage (6.6%) and vices (5.2%).

Central role of women: Gender roles and decision-making were mainly shared by both husband and wife.

Source: PPTA socioeconomic survey, June 2010.

1.3 EXISTING DRAINAGE SYSTEM/ FACILITIES

22. The drainage system in Butuan City consists of natural rivers/creeks and a network of roadside and off-road drainage systems. The latter drainage system is either closed (consisting of pipes or covered drains) or open (consisting of lined and un-lined trapezoidal or rectangular drains). Photographs of the existing drainage system are shown in Appendix 1.1.

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1.3.1 Existing Creeks/Waterways

23. Butuan City and environs are traversed by a series of creeks on both banks of Agusan River. The west bank, where the central business area is located, is drained by a complex system of interconnected natural creeks/channels, namely:

Masao River Maon-Villa Kananga-Libertad River Langihan Creek Lower Doongan-Suatan-Masao River T.Calo-Suatan-Masao River Doongan Creek Mandakpan-Bonbon Libertad-Masao River Agusan Pequeno River.

24. The above rivers drain a total area of approximately 83 km2. The Masao and Agusan Pequeno rivers are the main river systems into which the city’s drainage system discharge into. Figure 1.3 shows the existing river/creek drainage network on the west bank of Agusan River.

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Figure 1.3: River and Natural Drainage Network of Butuan City (West Bank of Agusan River)

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1.3.2 Urban Drainage System

25. In addition to the natural creeks, the existing urban drainage system in the city proper consists of a network of open (estero) or closed primary, secondary and tertiary channels/pipes. The open drains are mostly masonry-lined trapezoidal channels. However, in some areas of the city, the open drains have been filled in, replaced with under-sized pipes and covered with concrete slabs to allow access to building facilities, parking, and to serve as walkways for pedestrians. The filling in of the open drains have significantly reduced the flow capacity of the drains and contributing to flooding. The closed systems mainly consist of underground drainage reinforced concrete pipes ranging from 300 mm to 1200 mm in diameter. It was indicated by the City Engineer’s Office that some drainage systems in the city have been in existence for more than 30 years and need to be replaced as the systems can no longer cope with the increased amount of stormwater runoff generated, besides the systems being dilapidated.

26. Due to the topographic nature of the city, Jose C Aquino Avenue (the National Highway) serves as a drainage divide for the city’s drainage system. The main/primary drains north of the avenue either discharge north towards Agusan Pequeno River/Langihan Creek system or west into T. Calo-Suatan-Masao River, while the main drains south of Aquino Avenue discharge south towards Maon-Villa Kananga-Libertad River/Masao River system.

27. There are currently three (3) main existing sluice/floodgates along the levee/floodwall on the east bank of Agusan River. The gates can be found at the following locations:

At the downstream end of Rosales Street, near the Butuan Post Office. At the downstream end of Gomez Street. At the mouth of Agusan Pequeno River.

28. These gates control flow from Agusan River into the City’s drainage system. Although these gates serve a useful purpose of preventing flows from Agusan River from entering the city’s drainage system during flooding, they also prevent flows from the city’s drainage systems discharging into the river when the gates are closed during such crucial times. Should there be significant amounts of rainfall within the city’s catchments while the gates are closed, local flooding within the city occurs as no pumps have been provided to pump out the stormwater runoff from the city’s drainage system. CARBDP have removed the plates at some locations due to vandalism and theft. Thus, there is no control of flows to and from the channels at these locations, and therefore affecting the city’s drainage systems.

29. There is also a main flow control gate (Suatan Gate) located along the Lower Doogan-Suatan-Masao River. The purpose of this gate is to control incoming flows and tidal influence from the Masao River on the city’s drainage system. In all, there about 33 other minor gates within the drainage systems that control flows between the creeks and onto adjacent lands.

30. The City Engineer’s Office has indicated that drains under the jurisdiction of the city’s care have not been maintained since 2003 due to lack of budget and equipment. This has seriously impacted on the functionality of the drains, as some drains are clogged with acm3ulation of silt, solid waste and vegetation.

31. The layout of the city’s urban drainage system and facilities are shown on Figure 1.4. Photographs depicting the existing conditions of the drainage system are included in Appendix 1.1.

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Figure 1.4: Existing Urban Drainage System in Butuan Central Business District

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1.4 STUDY APPROACH AND METHODOLOGY

1.4.1 Introduction

32. The study approach to the preparation of the Butuan Drainage Master Plan Update comprised these main activities:

assessment of existing drainage situation; engineering investigations involving topographic and structure surveys,

hydrological and hydraulic analyses, identification of deficiencies and hydraulic constraints in the drainage systems, and determination of engineering interventions required for the drainage improvement works;

consultation with stakeholders on the proposed engineering interventions; formulation of the Drainage Master Plan.

1.4.2 Assessment of Existing Drainage Situation

33. Understanding and assessing the current drainage and flooding situation in order to identify deficiencies, hydraulic constraints, and to determine possible mitigation measures were some of the key aspects in the preparation of the Updated Drainage Master Plan. These involved the collection and review of existing data and reports including the previously prepared 2003 Butuan Drainage Master Plan by Butuan LGU, intensive field investigations, consultations with affected barangay, Butuan LGU, DPWH (Regional and District Offices; and CARBDP-Project Management Office), DENR, barangay captains and other relevant organisations. The consultations and field investigations provided vital information to the Consultant’s team and enabled a better appreciation of the current drainage/flooding situation in the Butuan central business area and surrounds.

1.4.3 Field Survey and Investigation

34. A survey contractor carried out drainage field surveys consisting of 1) a topographic survey of the central business district of Butuan City and 2) a structure survey of the existing drainage facilities. The survey report, including topographic map, is shown in Appendix 1.2.

35. For the datum and reference station of survey, the BCGS bench mark was used as the reference station of the survey. The elevation of the bench mark is 9.567 meters above mean sea level and is located on the sidewalk at the northwest corner of Magsaysay Bridge.

36. The reference station for the horizontal control is AGN-5, with the specific location as follows:

Latitude : 8-56-50.5032 Longitude : 125-32-36.2740 Northing : 989,471.893 Easting : 559,595.666 Location : On top of fire hydrant located at the southeast corner of the city plaza.

37. The elevation of the existing bench marks was measured in order to confirm the validity of the control points. Additional control points were established in the target area to facilitate the topographic survey. The additional control points were strategically located along the two major roads traversing the city proper; these are JC Aquino Avenue from east to west, and Montilla Boulevard from north to south.

38. The above vertical and horizontal controls are the same reference points used by the Cotabato Agusan River Basin Development Project (CARBDP) in the implementation of flood

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control projects in Butuan City

39. The topographic survey was carried out from June to August 2010. The duration of the field survey was delayed due to the onset of the rainy season, and the heavy vehicular traffic within the city proper which hampered fieldwork activities. Another cause of delay was the field audit conducted when the surveyor was required to return to the field for confirmation and additional data.

40. The scope of the topographic survey and mapping covered the road network and existing drainage facilities in the entire area of the central business district (CBD), including segments of Agusan Pequeno and Masao rivers that serve as the main drainage outfalls of the CBD.

41. The specific areas and boundaries that were covered by the survey are as follows:

Doongan road on the western side of City Hall which cuts through the completed open channel constructed by CARBDP; this channel serves as a tributary to the Masao River.

Agusan Pequeno bridge on the north side where Flood Gate No. 1 is located; this boundary serves as the outfall of the northern portion of the CBD.

Riverside road and floodwall from Barangay Bading to Golden Ribbon where Flood Gate No.2 (end of Rosales St. Bgy. Leon Kilat) and Flood Gate No.3 ( end of Gomez St. Bgy. Silongan) are located; these flood gates serve as the drainage outfall of low lying barangay adjacent to the Agusan River.

Villa Kanangga Bridge along Montilla boulevard on the south of CBD. Based on the topography, Villa Kanangga creek is the drainage outfall of the southern portion of the CBD including the capitol site and Guingona subdivision.

42. The longitudinal profile survey was carried out in order to measure the elevations of existing drainage structures, specifically the open channels along major roads within the city proper. These open channels are located along North and South Montilla Boulevard from Maon-Kanangga Bridge to Magsaysay Avenue, ER Ochoa St. from corner JC Aquino to Magsaysay Avenue, R Rosales St. from P Burgos to Magsaysay Avenue, Portions of JC Aquino from Magsaysay Bridge to Gen Rosales St., Langihan Creek from the Lagoon to the existing estero along Montilla Boulevard extension.

43. The drawing scale of profiles was 1:1,000 for horizontal and 1:200 for vertical. The accuracy of the traverse survey was 1:10,000 (closing error of coordinates).

1.4.4 Engineering Investigations

44. Following field assessment of the existing drainage situation in Butuan City and the collection of relevant data, engineering investigations involving hydrological and hydraulic analyses (desktop calculations only) were undertaken to develop feasible drainage concepts, size, cost and prioritize the required drainage infrastructure for the city.

45. It must be emphasized that the engineering investigations carried out during the study can be viewed as preliminary. This concept design should be regarded as basis for further investigations and development when actual field data is collected at a later stage of the project implementation. It is anticipated that the concept designs will be refined and updated during the preparation of detailed engineering designs.

46. Hydrological and hydraulic analyses are an important component of any drainage studies. The hydrological analysis involves the computation of flows which then serve as

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input to the hydraulic analysis. The hydraulic analysis mainly relates to the sizing and design of the drainage infrastructure. The design approach adopted was to provide adequately sized drains to convey stormwater runoff, up to and including the 10-year storm event, without overtopping of the drainage infrastructure. Philippines design standards/criteria prepared by DPWH, require that urban drainage infrastructure be designed for the 10-year average return period storm and hence the selection of the 10-year event for the design of the improvement works. Details of the hydrological and hydraulic analyses carried out are described further below in the report.

1.4.5 Formulation of the Updated Drainage Master Plan

47. The formulation of the Butuan City Updated Drainage Master Plan for drainage improvements and flood control in the city were based on an assessment of the existing situation, identification of the causes of flooding, outcomes of the engineering investigations, socio-economic and environmental assessments, construction and operational costs, and ease of implementation of the proposed improvement schemes.

48. The drainage improvement infrastructure has been designed to provide the affected areas with a flood immunity of up to the 10-year average return period event in accordance with recommended design standards for the design of urban drainage systems in the Philippines.

1.4.6 Consultations with Stakeholders

49. Community consultations to determine the needs and aspirations of people living in the flood-prone areas were carried separately as part of the overall project social survey. The outcomes of the consultations provided a good feedback to perceived improvements works required to reduce flooding in the affected barangay.

1.4.7 Details of Engineering Analyses

50. Hydrology – computation of stormwater flows. The Rational Method Hydrology was adopted for the calculation of peak discharges for the design of the drainage improvements. The methods outlined in the “Design, Guidelines, Criteria and Standards”, published by the Department of Public Works and Housing, Philippines were applied to the hydrological analysis.

Design Flow Computation 51. The Rational formula for calculating peak discharge is stated as:

Qy = 0.00278CyItc,yA,

where: Qy – peak discharge (m3/s) of return period of y years; Cy – runoff coefficient for y years for contributing sub-area; Itc,y – average rainfall intensity (mm/h) corresponding to the time of concentration (h) and return period of y years; and A – area of contributing basin (ha)

Time of Concentration

52. The time of concentration, which refers to the time taken for the stormwater runoff to travel from the most hydraulically remote part of the basin to the location of interest (basin

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outlet) is, in this case, made up of two components (entry time plus travel time in the drains). The time of concentration is required for the computation of rainfall intensities and subsequent computation of design peak flows.

53. The formula adopted for the computation of the Time of concentration is:

Tc = Te + Td where:

Tc – time of concentration in minutes. Te – time of surface water runoff entry into drains in minutes. Td – time of flow in drain in minutes.

The overland flow entry time was calculated using:

Te = 0.0196 L1.15/H0.385

where:

L – length of overland flow path. H – difference in elevation

54. An average drain slope of 0.001 for the computation of travel times in the drains was assumed for the calculation of Td. The selected value for the average minimum drain slope (0.001) was to ensure that self-cleansing velocities are achieved in order to minimize siltation in the drains.

Runoff Coefficient

55. The runoff coefficient depicts the fraction of rainfall which becomes runoff after considering rainfall losses such as soil infiltration, interception, surface storage, etc. The topographic nature of the areas, soil type, ground cover, and proposed future land use (extracted from the City Government Master Plan for 2010) were all taken into consideration in the selection of the runoff coefficient. With the above factors in mind, a runoff coefficient of 0.6 was considered appropriate for the city proper for the 10-year average return period design rainfall event.

Rainfall Intensity-Frequency-Duration Data 56. Recent Rainfall Intensity-Frequency-Duration (IFD) data for Butuan City, which is vital to the assessment and design of the drainage system, was not available. The IFD curves for Butuan City, as contained in the Updated Design for the Lower Agusan Development Project; Stage I, Phase II, (LADP-II) prepared in February 1999 was used for the hydrological analysis. The 10-year IFD Curve for Butuan City extracted from the LADP-II report is shown on Figure 1.5.

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Figure 1.5: 10-year Rainfall-Intensity-Duration-Curve for Butuan City

Source: “Updated Design for The Lower Agusan Development Project”, Final Report, Vol II-Appendices, Feb 1999.

57. Hydraulics – computation of drain sizes. The hydraulic analysis involved the computation of suitable drain sizes expected to convey the 10-year average return period design flows without the drains overtopping. The hydraulic capacity of the proposed drainage system to convey the 10-year design flows was assessed using Manning’s Formula for steady flow conditions and assuming free discharge at the outlet. In other words, tidal, backwater effects and flow reversals in the drainage system were not accounted for.

58. Manning’s formula is defined as:

Q = n

SAR 2/13/2

where: Q = discharge (m3/s); A = cross sectional area of drain (m2); R = hydraulic radius (m); S = slope (m/m); 0.001 assumed; n = Manning’s roughness coefficient (0.015 and 0.020 adopted for concrete and masonry respectively).

59. A spreadsheet was prepared for the hydrological and hydraulic analyses.

60. Due to the limitations in using Manning’s formula, in addition to the complex and interactive nature of the existing drainage system, it is proposed that a computer simulation of the drainage networks using more rigorous hydraulic analysis be carried out using a suitable urban drainage simulation model for the open and closed/pipe drainage systems when enough data is collected during the detailed design stage.

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1.5 SCOPE FOR DRAINAGE IMPROVEMENTS UNDER UPDATED MASTER PLAN

61. Scope. The scope for drainage improvements has been based on the outcomes of the engineering investigations and bearing in mind cost-effectiveness, social and environmental acceptability of the proposed works. The improvement works generally consist of:

Construction of new drains in the flood-affected areas where there are currently no drainage systems.

Replacement of existing under-sized drains by larger drains to increase the flow-carrying capacity of the drains.

Rehabilitation (dredging and repair works) of existing open drainage channels along major roads and streets.

Rehabilitation (dredging works) of existing main drainage channels/waterways. For closed/covered drains, construct additional stormwater inlets (catch basins) in

order to convey more flows from the surface and into the drains. Construction of flood/tide control gates and pump stations at selected locations to

control incoming tides, flows from Agusan River and evacuation of local stormwater runoff by pumping excess flows.

Implementing the segments of Langihan and Maon-Villa Kananga-Libertad Creeks which was not carried out by CARBDP because of problems with right-of-way and compensation issues.

62. Phasing. Three phases are envisaged to implement the full Butuan City Drainage Master Plan in accordance with the land use plan and priorities of the city government:

Phase 1, which is the Immediate Improvement Program (IIP), to cover the central business district (CBD). The major components for Phase 1 are as follows:

Construction of additional trapezoidal or rectangular drains on identified waterways along Villa Kananga, Agusan Pequeno and Langihan areas.

Construction of additional rectangular drains within the CBD and adjoining areas.

Replacement of non-functioning drainage lines along the CBD area. Rehabilitation of existing open drainage channels/waterways and along major

roads; this provision is considered based on the present heavily silted condition of the existing open channels.

Construction of pumping stations and floodgates along strategic portions of the CBD.

Phase 2 (medium-term) and Phase 3 (long-term) to cover the rapidly urbanizing areas located east of the Agusan River, and west of CBD up to Barangay Libertad. The major components for Phases 2 and 3 are as follows:

Construction of new trapezoidal drainage lines along identified drainage channels/waterways.

Construction of new rectangular drainage lines along roads/streets.

63. However, the estimated cost for all three phases (Appendix 3) is presently beyond the financial limitations and borrowing capacity of the city government (see analysis in Volume 7) and it is proposed that only Phase 1 is implemented under ARBIWRMP. Phase 1 can be viewed as a stand-alone project.

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1.6 PROPOSED SUBPROJECT SCOPE (PHASE 1)

64. Butuan City subproject drainage improvement will involve:

Rehabilitation and upgrading of the existing urban drainage system. Rehabilitation and upgrading of sections of Langihan and Maon-Villa Kananga-

Libertad Creeks. Construction of new drains in identified flood-prone areas where there are no

drainage systems. Construction of sluice gates and pump stations in selected locations. Institutional capacity building to improve the capability and efficiency of the city

government staff to properly manage and operate the drainage infrastructure.

65. The proposed Phase 1 works are summarized in Table 1.2 and illustrated on Figure 1.6.

Table 1.2: Proposed Butuan City Drainage Works (Phase 1) Item Description Unit Quantity

1. Trapezoidal Drain channels/waterways

1200mmx2500mm LM 5,400 1200mmx5000mm LM 3,000 1400mmx6000mm LM 2,800

2. Rectangular Drain channels/waterways

1200mmx5000mm LM 3,200

3. Rectangular Drain roads/streets 1200mmx1500mm LM 34,800 900mmx1200mm LM 38,400

600mmx1000mm LM 4,570

4. Rehabilitation of existing road open channels ( Dredging and Repair works)

LOT LOT

5. Rehabilitation of existing Main Drainage Channels/Waterways

( Dredging works) LOT LOT

6. Pumping Stations Nos. 6

7. Flood Gates Nos. 6

Source: PPTA Consultant.

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Figure 1.6: Proposed Butuan City Improved Drainage Works (Phase 1)

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66. Installation of tide/flood gates and pumping stations. Butuan Bay tides influence the outflow of the creek systems discharging into the bay and also causes backwater effects in the overall drainage system. This effect is further transmitted from the creeks and waterways into the city’s urban drainage systems and has the potential to cause flooding during periods of heavy rainfall due to the restriction of outflows. Besides the tides, flows from the city’s drainage system is also impeded by backwater effects and reverse flows from Agusan River when water levels in the river is higher than levels in the local creeks.

67. To overcome the above, tide/flood gates may be constructed at selected locations on some creeks to control incoming tides and Agusan River inflows into the city’s drainage system. Although the gates will control incoming tides and floods, it will prevent outflows from the local drainage system when the gates are closed, with the result that localized flooding could occur during heavy rainfall in the city. To mitigate this effect, there is the need to provide pumps to pump the stormwater from upstream to downstream of the gates in order to keep water levels in the city drains low and hence minimize any adverse effects on the discharge capability of the channels and avoid flooding in the city.

68. At present, there are three (3) existing floodgates located along the levee/floodwall on the east bank of Agusan River. These gates control flow from Agusan River into the city’s drainage system. However, no pumps have been provided to pump out the excess stormwater runoff from the city’s drainage system during heavy rainfalls when the gates are closed. The inability to quickly discharge stormwater runoff from the drainage system by pumping has resulted in flooding in some areas of the city, particularly in the vicinity of Butuan Post Office. CARBDP have removed the gate plates at some locations due to vandalism and theft. Thus, there is no flow control in the channels at these locations and therefore affecting flows from the city’s drainage systems.

69. To control movement of flows at the outfalls of the city’s drainage systems, the following are proposed:

Construct pumping stations at the locations of the three (3) existing floodgates. Construct new sluice gates and pump stations at the following locations (Figure 1.6):

o Along Lower Doongan Suatan-Masao River, near the intersection with Doongan Creek.

o Along T. Calo-Suatan-Masao River, near the intersection with Doongan Creek.

o Along the upper reach of Maon-Villa Kananga-Libertad River. 70. Besides, using the gates and pumps to control inflows and outflows at the main outlets of the city’s overall drainage system, the gates and pumps can also be operated to control flow of contaminated water from reaching and affecting the quality of water in the downstream fishponds.

71. It is suggested that more detailed investigations be carried out with regards to required pump capacities, gate sizes and locations of pump stations during detailed design.

1.7 STAKEHOLDER CONSULTATION WORKSHOP

72. A stakeholder consultation workshop was held on 5 October 2010 to present the overall scope of the drainage improvements, and there was general support for the proposals (a full report on the workshop is shown in Volume 9).

73. The scope and objectives of the workshop were to:

reaffirm the commitment from the city government to pursue the proposed Butuan City Drainage System subproject;

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identify and discuss specific issues and concerns in the design and the implementation of the proposed city drainage;

discuss safeguard policies regarding possible adverse impacts of the proposed subproject;

assess the acceptability of the proposed subproject to the affected residents, communities and businesses; and

outline the way forward leading to the realization of the subproject.

74. Reaffirmation from the City Mayor. The workshop was attended by the newly-elected Butuan City mayor and other high city government officials who reaffirmed that drainage improvement is a high priority of the city government.

75. Following initial discussions with the mayor on 9 September 2010 on possible financing options, further discussions were held with him on this aspect during the workshop.

76. Proposed subproject is highly acceptable by the stakeholders. Throughout the day’s discussion on the subproject interventions, everyone expressed positively on the need/relevance of the proposed city drainage subproject for the City of Butuan. Having experienced long wet days of flooding in most of the city, one participant said that is like a “light in a dark tunnel” of hope and aspiration for the city to attract more investors.

77. Another indicator of project acceptability by the stakeholders is on their active participation during the workshop. The majority of the barangay representatives stayed on and actively participated in all the activities. In fact, some City LGU senior staff who were not invited came in the afternoon to listen and to get more information of the subject matter.

78. Identification of common issues and concerns in the designs and implementation of the proposed subproject:

Social – Foremost among the issues identified and discussed was the displacement of informal settlers. Relocation sites are not much of a problem because the city government has already provided a site. Affected most is their livelihood, and the basic services that they can avail from any government agency that are accessible in terms of distances.

Economic – Closely related to social issues, dislocation of livelihood opportunities (need of alternative livelihood to the relocation site). Most of those who are affected are residing within the vicinity of the market and bus terminal areas whose means of income derived from small buy and sell vending.

Institutional – Lack of enforcement of existing government laws related to the drainage system (as well as other laws in the country). It has something to do with discipline and maturity as a good citizen/Filipino.

Environmental – Butuan City needs more cleaning up due to poor management of solid and liquid waste. The existing open dumpsite is within the heart of the city overlooking a river that flows directly to the sea.

Other Concerns – Acquisition and site development of resettlement areas to address basic needs of the community, especially on housing.

79. Suggested actions and recommendations for consideration of the subproject: The island at Lumbocan River to be included in the study. To include the portion of Barangay Tandang Sora, Pili Drive and Dagohoy in

the plan. City Government and Barangay Officials to fully support the project. Establish a benchmark in all barangay or a hydraulic gradient to determine the

lowest elevation of every barangay. Pass a legislation or ordinance to follow the elevation line.

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City Government should allocate funds for the establishment of vertical control.

Coordination with the City Government and other agencies for any infrastructure concerns.

Integrate drainage in any infrastructure development. Suatan Creek is to be considered and be a part of the study but not the

improvement and widening

1.8 ESTIMATED SUBPROJECT IMPACT AND OUTCOME

80. The impact of the subproject, when implemented, will be improvements to the living conditions of people in Butuan City who are currently affected by flooding and poor drainage.

81. The main outcomes of the subproject will be:

Reduction in frequency of local flooding in Butuan City. Improvements to the urban environment. Reduction in water-borne diseases and hence improvements to public health and

quality of life. Less disruption to livelihood/economic activities during the rainy season, due to

alleviation of flooding. Effective and efficient urban drainage system that minimises flooding and will

encourage flow of investment to Butuan City. Improvements to the managerial and operational efficiency and capacity of Butuan

City Government to properly manage and sustain the drainage infrastructure.

1.9 ESTIMATED INVESTMENT COST

82. The direct construction, operation and maintenance costs, and physical contingencies have been estimated. No allowance has been made for land acquisition, compensation and resettlement costs, and engineering and administration costs.

83. Construction cost estimates have been based on:

an assessment of quantities of work of various types that would be required and typical unit rates;

recent construction costs for similar works, undertaken in Butuan City, in particular, and elsewhere in the Philippines;

prices from specialist contractors.

84. The estimated cost for the Phase 1 Butuan drainage improvement works is shown in Table 1.3.

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Table 1.3: Butan City Drainage Cost Estimate (Phase 1) ITEM DESCRIPTION PHASE 1

Total Cost (P)

Year 1 (P)

Year 2 (P)

Year 3 (P)

Year 4 (P)

1. Trapezoidal Drain/ Waterway

1200mmx2500mm 6,177,600 6,177,600 1200mmx5000mm 6,786,000 6,786,000 1400mmx6000mm 11,284,000 11,284,000

2. Rectangular

Drain/Waterway

1200mmx5000mm 72,800,000 24,300,000 48,500,000 3. Rectangular Drain/Road

1200mmx1500mm 36,192,000 12,064000 12,064,000 12,064,000 900mmx1200mm 31,488,000 10,496,000 10,496,000 10,496,000 600mmx1000mm 14,570,000 4,856,000 4,856,000 4,858,000

4. Rehabilitation Works/

Dredging and repair works on open channels along Roads/Streets

10,000,000 3,500,000 3,500,000 3,000,000

5. Rehabilitation/ dredging Works on existing Channels/Waterways

5,000,000 2,500,000 2,500,000

6. Pumping Station 24,000,000 12,000,000 12,000,000 7. Flood Gates/Sluice Gates 2,400,000 1,200,000 1,200,000 GRAND TOTAL 220,697,600 70,863,600 70,916,000 78,918,000 Source: PPTA Consultant.

1.10 IMPLEMENTATION SCHEDULE AND CONTRACT PACKAGING

85. The estimated implementation schedule is shown in Figure 1.7.

86. Detailed engineering design will be carried at the start of project implementation, and survey requirements are outlined in Appendix 1.4.

87. Proposed contract packaging for the subproject is shown in Table 1.4.

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Figure 1.7: Proposed Implementation Schedule (Phase 1) Item Description Year 1 Year 2 Year 3 Year 4 Year 5 Year 6

Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Detailed engineering design

Preparation of tender dom3ents

Contractor procurement Construction: Trapezoidal Drain Channels/Waterways

Rectangular Drain Channels/Waterways

Rectangular Drain Roads/Streets

Rehabilitation Works Dredging and repair

works on open Channels along

Roads/Streets

Dredging Works on existing

Channels/Waterways

Flood Gates/Sluice Gates

Operation and maintenance

Source: PPTA Consultant.


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Table 1.4: Contract Packaging for Butuan Drainage Phase 1 Contract Package

No.

Contract Item

Contract Description Year of bid Contract

Type

Contract Item

Amount

Total Contract Package

Cost (P) (P)

1 1a Trapezoidal Channels on Waterways Year 1

NCB 24,247,000 97,047,000 1b Rectangular Channel on Waterway Phase 1 24,300,000 1c Rectangular Channel on Waterway Phase 2 48,500,000

2 2a Dredging and Rehabilitation works Year1

NCB 15,000,000 123,650,000 2b Rectangular Drains on Road Network 82,250,000 2c Pumping Stations and Flood Gates 26,400,000

Total 220,697,000 220,697,000 Note: NCB=national competitive bidding. Source: PPTA Consultant.

1.11 SUBPROJECT ACTORS AND THEIR RESPONSIBILITIES

88. The city government of Butuan: The maintenance of drainage facilities is the responsibility of the local government units and communities:

to ensure the cleanliness and sustainability of drainage system, the city government shall enforce the national law on the conversion of mangroves, and on establishment of settlements along easements of riverbanks;

the city government shall undertake continuing information and education campaigns on the importance of mangroves, and the role of communities and barangay in the maintenance of waterways; and

the city government shall define the roles and responsibilities of barangay and communities for the maintenance of drainage system; this may entail the passage of ordinances defining sanctions, etc.

89. Barangays along the drainage system: Barangay shall enforce/pass local legislation on the maintenance and non-

obstruction of waterways. Barangay shall monitor that the drainage system passing through their jurisdiction

is free of any obstructions such as garbage. The barangay government shall undertake continuing information and education

campaigns on the importance of mangroves, and the role of communities in the maintenance of waterways.

1.12 SEWAGE TREATMENT

90. During the workshop to present the Draft Final Report to key stakeholders held in Davao City on 25-26 November 2010, suggestions were put forward to include sewage treatment in the subproject scope since the drains in the CBD also collect sewage overflows from poorly constructed and maintained septic tanks and this poses a health risk to the city.

91. Howerver, although both LGUs and water utilities (in this case Butuan City Water District) are mandated under the 2004 Clean Water Act to address sewage and sanitation, and various technical solutions can be proposed (options are outlined in Appendix 1.5), the main consideration is the limited borrowing capacity of both Butuan City LGU and Butuan City Water District if sewage treatment is to be financed from loans. For Butuan City LGU its current borrowing capacity will be fully utilized for the proposed Phase 1 drainage works, and Butuan City Water District is not in a financial position to take on any further loans.


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1.13 RECOMMENDATIONS

1.13.1 Immediate/Short-term Strategies for Maintenance of Drains

92. Some of the drainage systems in the city, as they currently exist, are silted, heavily vegetated and contain acm3ulated solid waste as a direct consequence of lack of maintenance. In certain areas culvert structures are completely blocked by solid waste and water cannot flow through. These existing conditions of the drainage infrastructure have no doubt contributed to the flooding problems in the city.

93. To improve the hydraulic efficiency of the channels and minimise flooding in the short-term before the start of subproject implementation, it is recommended that the city government undertake a maintenance program to clean, de-silt and remove acm3ulated solid waste in the channels/drains and culverts.

94. The operation and maintenance program should be well planned taking into account resources, funds, equipment, etc, required. The program should be developed to include routine, periodic and emergency maintenance.

1.13.2 Implementation of Long-Term Measures

95. Implementation of the Updated Butuan City Drainage Master Plan. The Updated Butuan City Drainage Master Plan is intended to improve drainage and minimise flooding in the city in the long-term. In order to meet this objective, it is recommended that the long-term measures as outlined in the Master Plan (Phases 2 and 3) are implemented, depending on financing arrangements. A logical sequence of drainage improvements works should be adopted during implementation, not only to ensure continuity and uniformity, but also to derive maximum benefits from the proposed improvements.

96. Integration of drainage with infrastructure development. Careful planning of how stormwater runoff is to be managed is very important as it reflects the type of drainage infrastructure that needs to be put into place. Planning of the drainage system must always form part of the urban planning process. It is recommended that the city government ensures that all developments make provisions for adequate drainage prior to the approval and construction of such developments. Implementation of drainage infrastructure associated with proposed developments should be coordinated with Butuan City LGU.

97. Regulation and enforcement of building and landuse controls. There appears to be no regulation or enforcement of relevant legislation, policies, etc, relating to control of developments in flood-prone areas. In some cases, channels have significantly been narrowed, filled in or diverted to allow for the construction of buildings and other developments.

98. It is strongly recommended that Butuan City LGU and other government organisations be more vigilant and enforce the relevant regulations and policies in order to discourage the public from constructing structures in areas that impede drainage or obstruct waterways and thus have the potential to cause flooding.

99. Co-ordinatiion between Butuan City LGU and other agencies. In view of the current piecemeal approach in solving the drainage and flooding issues the city is facing, it is strongly recommended that all organisations involved in drainage activities such as DPWH, DENR and developers must coordinate their proposed drainage schemes with Butuan City LGU and should seek the latter’s concurrence before proceeding with such schemes. Good coordination will ensure an efficient and properly managed drainage system for the city.


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100. Creation of drainage easements and waterway reserves/corridors. It is recommended that waterway reserves be created along the existing channels in order to prevent future development or encroachment into the waterway areas. The creation of waterway reserves will also ensure minimisation of problems associated with land acquisition and compensation, and right-of-way in future in the flood-prone areas when the drainage improvement schemes are implemented.

101. Solid waste management. Dumping of solid waste in the drains or close to the drains by the public have resulted in the blockage of some drains and culverts, and consequently causing flooding. This practice, which is illegal, should be discouraged. It is therefore recommended that a solid waste management system, if there is none in place, be developed for the flood-affected areas in order to minimize or prevent this practice.

102. Wastewater management. Currently in Butuan City there is no conventional wastewater collection and treatment system. Wastewater from domestic households and effluents from septic tanks are discharged into the existing drainage system. This practice is no doubt polluting the city’s rivers and creeks, besides the health risks involved. To preserve the quality of water in the receiving rivers and creeks by controlling and minimizing pollutants from the city’s drainage systems, it is suggested that wastewater (domestic, industrial, commercial, etc) be collected and treated before discharging into the river systems. This would require providing a wastewater collection and treatment infrastructure for the city. In view of this, Butuan LGU should seriously consider undertaking a project to develop and implement an appropriate wastewater management system for Butuan.

103. It is recommended that a thorough feasibility study is carried out during ARBIWRMP implementation to determine the most appropriate technical, institutional and financing options.

104. Public education and awareness campaigns. The implementation and enforcement of regulations and policies relating to flooding and drainage control will not be successful without the strong support and watchfulness of the public. It is vital to develop support through formal education in schools and public awareness campaigns using the media and other sources. It is recommended that the city government embarks on a public awareness campaign to educate the public in the flood-prone areas on how to minimise flooding and its associated risks and damages.

105. The city government should lobby barangay located in the flood-prone areas for support to provide labour and other assistance to maintain the channels and culverts as this is of benefit to these barangay.

106. Collection of flood data. It is recommended that the city government establishes a program to collect data on major flood events as and when they occur in the city. The data to be collected should include depth, extent, duration of flooding, damages caused and the mechanism of flooding. This information will provide relevant data on flood damage assessments and other information required for the planning of future drainage schemes and also for flood disaster management.

107. International trend in urban stormwater management. Many developed countries are moving away from the traditional approach to urban drainage (which is to protect against flooding by rapidly collecting and conveying stormwater runoff) to the management of stormwater runoff. Stormwater management involves managing both the quantity and quality of stormwater runoff and its impacts on the general environment (physical and biological). It requires coordinated efforts of professionals from various disciplines such as engineers, public health officers, environmentalists, etc, and of course, the community. The new approach to stormwater management is to take an integrated and co-ordinated total


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catchment approach to the issues of stormwater management. It is worthwhile for Butuan City LGU to take note of international trends in stormwater management and make efforts to adopt these in the near future.


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APPENDICES

1.1 Photographs of Existing Drainage System in Butuan City

1.2 Field Survey and Investigation Report and Map

1.3 Scope and Cost Estimate of Interventions under Updated Butuan City Drainage Master Plan

1.4 Survey Requirements for Detailed Engineering Design

1.5 Butuan City Sewage Management and Treatment Options for the Central Business District – Framework for Sewerage Planning


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APPENDIX 1.1: PHOTOGRAPHS OF EXISTING DRAINAGE SYSTEM IN BUTUAN CITY


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APPENDIX 1.2: FIELD SURVEY AND INVESTIGATION REPORT

Objective Field surveys and investigations were conducted to obtain new information and/or augment existing data that were necessary in the formulation of the drainage master plan and in the preparation of the preliminary engineering design for the Butuan City Drainage Improvement Subproject. The instrument survey started on June 23, 2010 and was completed, inclusive of fieldwork, computations and plotting, over a period of two and a half months. Field progress was affected by the onset of the rainy season and the heavy vehicular traffic within Butuan City which caused delays and suspensions of fieldwork activities. Another cause of delay was the field audit conducted requiring the survey team to return to the site to confirm and include additional information as required by the PPTA Consultant. Topographic Survey

Scope of Activities The topographic survey scope included:

1. Mapping of the entire road network within Butuan City Central Business District (CBD).

2. Spot elevations of the road network, specifically at street intersections, bends, bridge crossings, and at every 50 meters interval of road.

3. Structure survey of existing drainage facilities within the CBD. 4. Longitudinal survey of existing waterways located within the CBD drainage influence

areas.

Area Coverage Control points were established along the four quadrants created by the intersection of the two major roads dissecting the CBD. These are: JC Aquino highway from Magsaysay Bridge going westward to Misamis Oriental, and Montilla boulevard from Maon-Kanangga Bridge on the south and towards Magsaysay Avenue on the north. (See topographic map for locations).

The specific areas and boundaries that were covered by the survey are as follows:

Along Doongan road on the northwest quadrant where the City Hall is located. Doongan road cuts through the completed open channel constructed under CARBDP. This open channel serves as a collection channel that drains to the Masao river.

Agusan Pequeno bridge on the northeast quadrant where Flood Gate No. 1 is located. This boundary is the starting section of Agusan Pequeno River that serves as the outfall of the northern portion of Butuan City.

Along the riverside road and floodwall from Barangay Bading to Golden Ribbon where Flood Gate No.2 (end of Rosales St., Leon Kilat) and Flood Gate No.3


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(Gomes St., Silongan) are located. These flood gates serves as the drainage outfall of low lying barangay east of Montilla Boulevard and adjacent to the Agusan River.

Villa Kanangga Bridge along Montilla Boulevard on the south of city proper. Villa Kanangga creek is the drainage outfall of the southwest portion of Butuan City, including the Capitol site, Guingona subdivision, Golden Ribbon and Maon.

Survey on Drainage Structures Details of survey on specific areas of Butuan City proper are described below:

- Along Ipil Road to P. Burgos, Barangay Tandang Sora. The connection of the open canal from Ipil road crossing JC Aquino to P. Burgos was obstructed by permanent commercial structures. The encroachment is up to the next block along P. Burgos extension where the structures are directly above the drainage channel. Water in the drainage canal is stagnant.

- Capitol site and Guingona Subdivision. The area has existing drainage structures (combination of 600 to 900mm rectangular drains). This area is presumably draining either to the existing open channel along south Montilla Boulevard or directly into the Kanangga creek. However, there are no drainage structures connecting this area to the perceived outfall. Water inside the drainage lines is stagnant.

- Portion of Barangays Imadejas, Dagohoy and Lapulapu located north of the Capitol site and are draining along JC Aquino.

- Open channel at Montilla Boulevard. The stretch of open channel on the west side of Montilla Boulevard extends from Maon Kanangga bridge up to Magsaysay Avenue in Barangay Obrero. Access to the open channel is very difficult since most of the open channel is obstructed by permanent structures serving as parking space or commercial space. Up to the time of the survey, construction of permanent structure on top of the open channel is ongoing. Although the open canal is heavily silted, water is flowing freely in the southward direction, while flow in the northward direction is sluggish and almost stagnant.

- Lateral Drainage Structures. These are the original drainage lines consisting of CHB canal with concrete cover located at the city center near Magsaysay Bridge. The area comprises Barangays Leon Kilat, Humabon, Sikatuna, Urduja, Silongan, Diego Silang, Raja Soliman, Agao New Society Village and Tandang Sora. There are about 4.8 kilometers of these lines, 95% of which are presumed to be not functioning since all manholes are heavily silted and dilapidated. Taking of invert elevations of existing drainage lines in this area is impossible. Only the drainage lines connecting to the 2 existing flood gates are likewise silted, but flowing.

- Barangay Golden Ribbon and Maon. These two barangay have no existing drainage facilities. The road network in the area is not defined except for San Vicente St. which is parallel to Montilla Boulevard.

- Barangays San Ignacio and Ong Yiu. These are in the low lying or swampy area within the city proper. Except for visible narrow pathwalks, there are no defined road networks within the barangay, and most spaces are occupied by temporary houses or shanties. These barangay form a high density area. The elevation of these barangay is relatively lower compared to the elevation and profile of Montilla Boulevard on the


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west side where the open channel is located. The area is likewise lower than the elevation of the riverside road on the opposite side of the barangay.

- Open Channel at R. Rosales St. This concrete-lined open channel is heavily silted and constricted at intersections from T. Calo up to the existing estero along Magsaysay Avenue. The open channel is passing through Langihan public market and the bus terminal before it drains at the existing estero along Magsaysay Avenue. Water in the open channel from the public market to T Calo is stagnant.

- Open Channel at ER Ochoa Avenue. This open channel is a combination of rubble riprap and earth canal that drains towards Magsaysay estero and the existing lagoon. The open channel is constricted due to encroachment as it approaches Magsaysay Avenue. The condition is similar to the open channel at R. Rosales St.

- Langihan Creek. The upstream of this waterway is the existing lagoon located north of the Langihan Public Market and the bus terminal. The creek flows downstream into Barangay Bading and into Agusan Pequeno River or the tributary of the Masao River. During the survey period, the waterway was heavily silted and full of debris. Squatters are staying on both sides of the waterway, extending to about 400 meters downstream. When the survey audit was conducted, the squatters in the area had been removed.

- Holy Redeemer. The barangay is a high density area with temporary structures. The existing estero in this barangay is the outfall of ER Ochoa and R. Rosales open channels before it drains into the Langihan creek. The existing estero is constricted on both ends. The flow going to Langihan creek is blocked by permanent structures which encroach on the waterway from Magsaysay Avenue up to the intersection of Langihan creek. On the opposite side, the estero is only up to ER Ochoa and a shallow natural canal going to Gen Rosales St. and ultimately flowing into Doongan creek. Water in the existing estero is stagnant and full of debris.

Reference Datum and Benchmarks The BCGS bench mark was used as reference station of the survey. The elevation of the bench mark is 9.567 meters above mean sea level. The benchmark is located on the sidewalk at the northwest corner of Magsaysay Bridge.

The reference station for the horizontal control is AGN-5 with specific location as follows:

Latitude : 8-56-50.5032 Longitude : 125-32-36.2740 Northing : 989,471.893 Easting : 559,595.666 Location : On top of fire hydrant located at the southeast corner of the city plaza.

The elevation of the existing bench marks was measured in order to confirm validity of the control points.

Additional control points were established along the target area to facilitate the topographic survey.The additional control points were strategically located along the two major roads traversing the city proper. These are JC Aquino Avenue from east to west, and Montilla Boulevard from north to south.

The above vertical and horizontal controls are the same references points as used by the Cotabato Agusan River Basin Development Project (CARBDP) in the implementation of flood


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control projects in Butuan City.

The scope of the topographic survey and mapping covered the road network and existing drainage facilities located w

Documents

VOLUME 4faspselib.denr.gov.ph/sites/default/files... · TA No. 7258-PHI: Agusan River Basin Integrated Water Resources Management Project – FR – Vol. 4 FINAL REPORT Pöyry IDP