phi pda: technology to cope with debris flows in mountain regions (final report)

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TA6325 – REG:Promoting Effective Water Policies and Practices (Phase 5)

– Pilot and Demonstration Activity for Philippines:

Testing and Demonstrating a Technology to cope with

Debris flows in Mountain Regions

Project Completion Report

December 2008

International Centre for Water Hazard and Risk Managementunder the auspices of UNESCOPublic Works Research Institute

The views expressed in this paper/presentation are the views of the author and do not necessarily reflect the views or

policies of the Asian Development Bank (ADB), or its Board of Governors, or the governments they represent. ADB

does not guarantee the accuracy of the data included in this paper and accepts no responsibility for any consequence

of their use. Terminology used may not necessarily be consistent with ADB official terms.



Testing and Demonstrating a Technology to Cope with Debris flows in Mountain Regions

Abbreviations

ADB Asian Development Bank

ICHARM International Centre for Water Hazard and Risk Management under the auspices

of UNESCO

JICA Japan International Cooperation Agency

DPWH Department of Public Works and Highways

DENR Department of Environment and Natural Resources

NEDA National Economic Development Authority

PAGASA Philippines Atmospheric，Geophysical and Astronomical Services Administration

PHIVOLCS Philippines Institute of Volcanology and Seismology

PWRI Public Works Research Institute

DMI DMI Construction




Acknowledgement

We would like to thank the Asian Development Bank (ADB) for providing financial support for this

Pilot & Demonstration Activity (PDA) program to promote effective water management policies and

practices. We would also like to thank Mr. Wouter T. Lincklaen Arriens (lead water resources

specialist of ADB), Mr. Ian W. Makin (senior water resources management specialist of ADB), Ms

Ellen Pascua (deputy water fund manager of ADB) and Mr.Dennis Von Custodio (water financing

program adviser of ADB) for their valuable suggestions and feedbacks for the success of this project

successful.

We are also thankful to the National Economic Development Authority (NEDA), the Department of

Environment and Natural Resources (DENR), and the Department of Public Works and Highways

(DPWH) for providing proper assistance to launch the project.

We would also like to extend our thanks to Mr. Resito V. David (director of FCSEC of DPWH) and

the late Mr. Leo A, Alhambra (director of the Planning and Design Division of the CAR Regional

Office of DPWH) for their constant support and help during the implementation of the PDA activity

in the field.




Table of Contents Abbreviations

Acknowledgement

Executive Summary.................................................................................................................................... 1

1. Introduction – Background and Context .............................................................................................. 2

1-1. Development Context of the Project ............................................................................................... 2

1-2. New Low-Cost Technology for both Structure Building and Maintenance ................................. 2

1-3. Challenges ........................................................................................................................................ 4

1-4. Objectives of the Project .................................................................................................................. 4

1-5. The project area and its relevance .................................................................................................. 4

1-6. Administrative procedure required ................................................................................................ 7

2. Objectives - Methods Applied and Main Outputs................................................................................. 7

2-1. Methods applied and processes followed and the rationale.......................................................... 7

2-2. Mapping and Geomorphological Analysis ...................................................................................... 7

2-3. Main Outputs ................................................................................................................................... 8

1) the Location of the Project ........................................................................................................... 8

2) the Location of the Debrisflow Brake ......................................................................................... 8

3) Materials for the Brake ............................................................................................................... 8

4) Assessment of Debris-flow Discharge ......................................................................................... 8

3. Activities .................................................................................................................................................. 9

3.1. Construction of the Debris flow Brake ........................................................................................... 9

3.1.1. PROJECT DESCRIPTION ....................................................................................................... 9

3.1.2. Planning and Design Criteria .................................................................................................. 9

3.1.3. Designing Highlight ................................................................................................................ 14

3.1.4. Construction Schedule ............................................................................................................ 14

3.1.5. Actual construction Schedule ................................................................................................. 14

3.1.6. As-Built Drawings ................................................................................................................... 15

3.1.7. Photographs ............................................................................................................................. 15

3.1.8. Material Test Result ................................................................................................................ 17

4. Financial Status .................................................................................................................................... 19

5. Monitoring and Maintenance Practices .............................................................................................. 22

5-1. Monitoring practices on deformation of the slit materials ......................................................... 22

5-2. Monitoring practices on mobile materials and changes in channel conditions......................... 22

6.Conclusion and recommendations ........................................................................................................ 23




List of Appendices

Appendix- 1: Government’s No Objection on the Project

Appendix- 2: Terms of Reference for the Project

Appendix- 3: Contract Agreement between DMI Construction and PWRI

Appendix- 4: Detailed Structural Design

Appendix- 5: Concrete Mix Design

Appendix- 6: Proposed Work Schedule

Appendix- 7: Actual Work Schedule

Appendix- 8: Letter of Completion and Turn Over

Appendix- 9: Structures Completed

Appendix-10: Complete Certificate

Appendix-11: Report of Completion

Appendix-12: Concrete 7 Days Old Strength Test

Appendex-13: Concrete 20 Days Old Strength Test

Appendix-14: Supporting Documents substantiating Expenditures




1

Executive Summary

The Pilot and Demonstration Activities (PDA) Program for Water in the Philippines was launched in

May 2008 to reduce the risk of disasters due to direct hits by debris flows on vehicles driving on a

road crossing a debris flow-prone valley and on small settlements located on an alluvial cone in

mountainous regions.

A technology employed for the project is referred to as dehydration technology, or debris-flow

brake, which is featured by horizontal slits set up across a torrent bed. A debris flow is a multiphase

flow which generally consists of solid particles, water, solid materials such as drifting woods,

sometimes fragments of housing materials, and vehicles, depending on the situation of a catchment.

Unlike particles in an ordinary flow, those in a debris flow gain kinetic energy from not running

water but particles themselves colliding with one another.

As soon as a debris flow reaches a dehydration structure, its water component drains while the

flow is running on the screen, or horizontal slits, of the structure. As the debris flow loses its water

component, the mechanism of the energy transmission by particle collisions can no longer work

because of the friction sharply increasing among the particles. A debris flow, no matter how large in

terms of volume and particle size, will make automatically a stop.

For the slit structure of a brake, locally available materials, such as wood and reinforced concrete

beam, can be used depending on the weight and size of the boulders contained in a projected debris

flow.

A project site was selected at the 241km distance post on Kennon Road in Baguio City, Benguet

Province (see photograph 2). The site was selected also because the Philippines expected that it

would show a higher showcase effect and security against vandalism in addition to the physical

effect.

In this project, a debris-flow brake with a 10-meter-long slit cost US$48,400, which is far less

than other structures made of either massive concrete or steel materials. In addition, brakes require

no specific and sophisticated skills in designing, building and maintaining.




2

1. Introduction – Background and Context

1-1. Development Context of the Project

Flash floods due to torrential rainfall frequently result in debris flows in mountain regions and

alluvial cones.

Disasters due to flash floods and associated debris flows are quite common natural phenomenon

in tropical and semi-tropical regions. Statistics shows that mountain regions in the Philippines have

been hit by sever flash floods and suffered from a number of disastrous events.

It is well known that rainfall with high intensity and mobile materials detached from steep slopes

and torrent beds are responsible for the initiation of debris flows. The number of disasters due to

flash flood and debris flow has been dramatically increasing over the past decades as a result of

increase in settlements and their expansion in rural areas, multiple land use such as resorts and

souvenir shops, slash and burn farming practices on slopes, and particularly transportation roads in

mountain regions.

Impacts of debris-flow disasters in the Philippines along with many other countries in Asia, such

as Thailand and Nepal, have been further increasing due to the destruction of vegetation cover

which, at the same time, resulted in massive environmental devastation.

In addition to the causes mentioned above, it is pointed out that debris flows will increasingly

become a major disaster threat at the regional and global level, especially in high mountain regions

due to permafrost melting triggered by global warming. This increasing trend will also become a

major threat to social safety and to settlement areas along roads and on alluvial cones in valleys.

Enormous efforts have been made in an attempt to eliminate the causes of disasters due to debris

flows and reduce their devastating impacts through prevention, protection and preparedness.

Nevertheless, kinetic energy carried by flash floods and associated debris flows, once they start

running, is so destructive that nothing can mitigate their power except massive and costly

engineering structures made of either steel or concrete. As a result, a lot of lives have been lost and

traffic has been disrupted in mountain regions in which little resources are available.

Due to financial difficulties along with those in displacing local people and conducting road closure,

preventing a debris flow from developing into a disaster is only possible by employing new

technologies requiring low cost for structural building and maintenance and lesser skills for

planning, building, monitoring and maintenance practices, as well as promising highcost-effectiveness.

1-2. New Low-Cost Technology for both Structure Building and Maintenance

A new, easy-to-transfer and feasible technology has been developed to cope with disasters due to

debris flows. The effectiveness of the new technology has been proven by intensive laboratory tests




4

Flow Brake is set up in the immediate upper side of a paved road crossing a torrent.

Based on successful demonstration projects in both Japan and Switzerland, this technology

undoubtedly offers a best alternative which is low cost and feasible to protect settlements under the

threat of debris flows in rural areas and prevents traffic disruption in high-mountain regions

throughout the world.

The dehydration technology employing horizontal slits across debris flow-prone torrents is quite

effective in mountain regions, such as the Atlas in the north Africa, Balkan, European Alps, the

Tenshan, the Himalaya, the Circum Pacific Fire Belt and adjoining areas.

1-3. Challenges

A demonstration project was proposed to prove the following five points:

(1) The dehydration effect is the key to brake debris flows.

(2) The dehydration effect can be achieved by setting up horizontal screens across a torrent.

(3) The structure is easy to build and maintain at low cost.

(4) The technologies required for designing, building, monitoring and maintaining a Debris-Flow

Brake are easy to master.

(5) The technologies are applicable to debris flow-prone sites throughout the world.

In order to conduct the above project, a debris-flow-prone site at its 241km distance post on

Kenon Road was selected as the most appropriate demonstration site.

1-4. Objectives of the Project

The objectives of the project were five folds as follows;

1) Reduction in number of killed and affected people by debris flows

2) Reduction in property damage

3) Reduction in frequency of traffic closure

4) Reduction in cost for building preventive structures

5) Reduction in work load to remove debris accumulated on the torrent beds after heavy rainfall and

associated debris-flow discharges

1-5. The project area and its relevance

Along and across the Sierra Madre Mountains in Luzon and in the further south islands, a lot of

human settlements, as well as many livelihood activities such as souvenir shops and restaurants,

have developed. The highways in this area are of vital importance to secure logistics, rural economic

development, and passenger services. The human security and social and livelihood activities in

these mountain areas are however threatened by the high risk of debris flows and associated

disasters.

Sites at higher risk correspond to ones at which a road is crossing a torrent perpendicular to the

road. Vehicles and pedestrians usually cross torrents by bridges or culverts, but the channel




6

Figure 2 Location of the Project




8

movements.

The alignment and planimetric shape of the channel is featured by rectangular bend due to a

conjugated fault.

2-3. Main Outputs

1) the Location of the Project

The location of the project site was determined taking into account, firstly, the possibility of

debris-flow discharge, and secondly, the high risk of disasters due to direct hits by debris flows on

the beneficiaries, traffic, passengers, pedestrians and local people.

2) the Location of the Debrisflow Brake

The location of the Debris-Flow Brake and the dimensions of the structures were determined

taking into account the physical features of the catchment basin and the site. The lower end of

the brake is located at the second fall while the upper end is located at the fourth fall (see

Appendix 3-4).

3) Materials for the Brake

The brake consists of a groundsill, two retaining walls made of concrete, and three steel beams

and rectangular steel tubes for the slit structure (see Appendix 4-3). Although wood materials,

such as coconuts lumber, were recommendable for the slit structure, they were not available at

the local market because logging was strictly prohibited.

4) Assessment of Debris-flow Discharge

The projected quantity of a debris-flow discharge must, basically, be determined based on a

hydrograph and relevant morphological data, but no such data was available. Instead, the peak

discharge was assessed at 1.0m3/sec based on the size of the catchment (0.15 km2), rainfall

intensity in the 100-year period (300mm/hr), and passing capacity of the channel. It was

observed that the front part of a debris flow contained boulders and water in the same proportion

of 50%. This means that the peak discharge of a debris flow can be two m3/sec.

The channel capacity was considered to have large enough to accommodate the water

component of the peak discharge.

It was assumed that the front part of a debris flow would stop its motion as soon as it passes

the 5th fall because of high energy-dissipation effect of the pool between the 4th and 5th falls (see

Appendix 3-4).

Although a debris-flow spilled out of the pool was assumed to continue running on the screen

made of steel slits, it would make a sudden stop forming a debris lobe on the brake because of

strong internal friction as well as resistance forces working among the particles as a result of

the dehydration effect of the brake.

It was therefore assumed that a subsequent debris flow would stop when reaching the location of

the lobe formed by the previous debris-flows. Likewise, the debris lobe would grow towards the upper

reach as a subsequent flow would supply additional debris because of high permeability of lobes. It is




9

therefore no need to build a massive structure to prevent debris flows from flowing further

downstream.

3. Activities

3.1. Construction of the Debris flow Brake

3.1.1. PROJECT DESCRIPTION

The project site was located at the 241km distance post on Kenon Road in Baguio City. This

project was proposed by the International Centre for Water Hazard and Risk Management

(ICHARM) of the Public Works Research Institute (PWRI) under the auspices of UNESCO, funded

by the Asian Development Bank. and implemented under the supervision of Engineer-In-Charge

Masayuki Watanabe and Researcher Shinichi Hasebe of the Flood Control and Sabo Engineering

Center (FCSEC) of the DPWH, Philippines.

The Construction included the following:

a. Site topographic survey

b. Project detailed engineering design

c. Construction of the structure

d. Construction supervision and management

The project started on October 1, 2008, and was at first scheduled to be completed on December

30, 2008.

However, the project ended on November 24, 2008, which is more than one month earlier than

initially scheduled, thanks to the close cooperation of the DPWH Regional Office in Baguio and thepeople of local communities.

3.1.2. Planning and Design Criteria

A rough sketch of the dehydration structure was made based on the reconnaissance study

conducted in May. The contractor prepared a detailed design based on the detailed topographic map

prepared under the contract agreement. PWRI fixed the basic conditions for planning and designing

as described on the following pages.




10




11




12




13




15

and grouted riprap instead of rock fill as design. All slits and beam joints were fully welded.

3.1.6. As-Built Drawings

As-Built drawings are given in Appendix 9.

3.1.7. Photographs

Photograph 1. The slopes at the center if the target Catchment Basin

Photograph 2. 241 km post of the Kennon Road

The road crosses the target torrent at this point.




16

Photograph 3. Initial condition of the debris flow-prone torrent

Photograph 4. Debris-Flow Brake

Photograph 5. Around the 241km distance post on Kennon Road

Traffic is vulnerable to a direct hit of a debris flow




17

Photograph 6. Debris-Flow Brake secures traffic safety

Photograph 7. The upper end of the Debris-Flow Brake

The slits are fixed on the top of the groundsill

located at the 4th fall.

3.1.8. Material Test Result

1) Seven-day-old concrete was tested for strength (see test results in Appendix 12). Based on the test

results, it was projected that the concrete would also pass the design strength of 3,000 psi after 28

days.

2) The test results of the 20-day-old concrete is presented in Appendix 13.

3) An indirect strength test was conducted at the site on November 25, 2008, applying the Schmidt

Hummer method (see Photograph 8 and Table 1).




18

Photograph 8. Schimdt Hammer test

The hammer score showed more than 20 at almost all hitting points (Table 1). This level of

hammer score is equivalent to 100 kg/cm2 in uniaxis compression strength for the 7-day-old concrete.

This is usually considered to well satisfy the target strength of 28-day-old concrete, or 250 kg/cm2.

Table 1 Score of Schmidt Hammer Test

Hitting

Point

Hammer

Score

Compression

Strength(kg/cm2)

Hitting

Point

Hammer

Score

Compression

Strength(kg/cm2)

Upper 1 20 104 Lower 20 22 110

2 28 200 21 18 90

3 22 110 22 17 95

4 27 198 23 32 255

5 36 305 24 25 160

6 37 300 25 31 215

7 21 100 26 26 165

8 21 100 27 35 300

9 20 98 28 28 200

10 21 100 29 32 255

11 33 260 30 36 305

12 24 150 31 20 9813 23 145 32 17 80

14 25 160 33 28 200

15 26 160 34 23 145

16 22 110 35 21 100

17 23 145 36 28 200

18 20 98 37 25 160

19 15 75 38 36 305




19

4. Financial Status

The financial status of the project is described in Form 14 and 15, which were given in the Letter of

Agreement between ADB and PWRI.

Form 15 shows that a total of $30,358 was in short chiefly because the construction fund had not

been fully remitted.

The cost for the two missions for the grand survey and bidding arrangements in the Philippines

and the cost for consultancy services performed by Mr. Masayuki Watanabe in Japan and the

Philippines were paid by PWRI following its provisions on budget spending set under the Japanese

government’s rules.

Although the receipts issued by the hotels in Manila and Baguio are attached in this report, it

must be noted that an expatriate personnel dispatched by the government of Japan, as far as travel

cost is concerned, is not requested to present corroborating evidence, such as receipts issued by

hotels, in order to justify his/her trips.




20

Form 14LIQUIDATION OF ADVANCE - STATEMENT OF EXPENDITURES ( SOE)

TA No.:6325 Project Name: Pilot and Demonstration Activity for Philippines: Testing and Demonstrating a Technology to Cope with

Debrisflows in Mountain RegionsLiquidation of Advance

Statement of ExpendituresFor the period: from 1 June 2008 to 19 December 2008

ItemNo.

Description of Goodsand Services

Payee(Supplier/

Contractor)

Date ofPayment

Amount Paidin Local Currency

US DollarEquivalent

Remarks

1-1 Construction Work DMIConstruction

16Oct2008 $12,100 $12,100

1-2 Construction Work DMIConstruction

10Dec2008 $36,300 $36,300

2-1 International Trip(25-27 Aug)

￥182,738 $1,781 ￥102.6/$

Air Fare JAL 25Aug2008 ￥104,640.

Airport Tax Manila Airport

Authority

25Aug2008 P750(￥1,935)

Rent a Car Grace CarService

27Aug 2008 US$255(￥28,123)

Per Diem(fixed PWRI rate)(￥5000/day for 3days)

27Aug2008 ￥15,000.

Accommodation(fixed PWRI rate)(@￥15,100 for2nights)

27Aug2008 ￥30,200.

Transport (in land) 27Aug2008 ￥2,840.

2-2 International Trip (23-27Nov)

￥220,049 $2,423 ￥90.8/$

Air Fare JAL 23Nov2008 ￥85,540

Airport Tax Manila

Airport Authority

23Nov2008 P750

(￥1,552)

Rent a Car Grace CarService

27Nov2008 P21,294.(￥44,717)

Per Diem(fixed PWRI rate)(￥5000/day for 5days)

27Nov2008 ￥25,000

Accommodation(fixed PWRI rate)(@￥15,100 for4nights)

27Nov2008 ￥60,400

Transport (in land) 27Nov2008 ￥2,840

Total$52,604

It is hereby certified that the above amounts have been paid for the proper execution of the Technical Assistance activities, all within the terms and conditions of the Technical Assistance Agreement.

All supporting documentation substantiating these expenditures will be made available upon requestby ADB.

______________________________ _____________________________Name and Signature Name and Signature

Team Leader Project Director or ManagerMasayuki WATANABE Hiroshi WADA,

Director o f General Affairs, PWRI




21

Form 15LIQUIDATION OF ADVANCE - STATEMENT OF EXPENDITURES (SOE)

TA No.:6325 Project Name: Pilot and Demonstration Activity for Philippines: Testing and Demonstrating a Technology to Cope withDebrisflows in Mountain Regions

Project Financial Status for the Period: from 1 June 2008 to 19 December 2008 (US Dollars)

Item or Category

ApprovedCost

Estimates(a)

Actual Expenditures BalanceOf Cost

Estimates(a-b)

CurrentPeriod

CumulativeFrom Start to Current

(b)FUNDS RECEIVED

(c) US$ConstructionWork

16Oct08ConstructionWork$12,100

10May08 $10,000.00$47,500

10Dec08 $36,300$48,400 $-900

InternationalTrip InternationalTrip

26Aug08 $12,245.8025-27Aug08 $1,781

$2,50023-27Nov08 $2,423

4,204 $-1,704Contingencies

$5,000 0 $5,000GRAND TOTAL

$22,245.80 $55,000 (d)$52,604 $2,396

FUNDS BALANCE(c-d) US$--30,358.2

It is hereby certified that the above amounts have been paid for the proper execution of the Technical Assistanceactivities, all within the terms and conditions of the Technical Assistance Agreement.

All supporting documentation substantiating these expenditures will be made available upon request by ADB.

______________________________ _____________________________Name and Signature Name and Signature

Team Leader Project Director or ManagerMasayuki WATANABE Hiroshi WADA,Director of General Affairs, PWRI




22

5. Monitoring and Maintenance Practices

5-1. Monitoring practices on deformation of the slit materials

Debris-Flow Brakes are generally vulnerable to impact forces due to weight and kinetic energy of

debris in motion. In this project, the steel members of the brake might be deformed due to debris

weight if the thickness of debris accumulated on the screen exceeds the design thickness of one

meter.

The thickness of the top panel of the rectangular tubes might get thinner as time passes due to

frictional forces working between the tubes and debris in motion. Deformation might therefore get

larger as time passes. The rectangular tubes must therefore be replaced if cracks are found on their

surface.

In order to extend the life span of the brake, the tubes must be closely monitored for deformation.

It is rather difficult to monitor possible deformation on the top panel of the brake. Deformation

must therefore be monitored by measuring the distance between the bottom of the creek and the

basal plates of the brake.

5-2. Monitoring practices on mobile materials and changes in channel conditions

Major debris sources must be, firstly, the cliff at the headwater of the creek. Materials on the cliff

easily break off in case of earthquake, and are easily carried down by a debris flow to the first

crossing point between Kennon Road and the torrent. The debris flow can continue cascading down

picking up additional materials from a mining yard developed beside the road.

The retaining walls of the sludge stock yard must be strengthened, and the channel running

through the mining site and the first crossing point must be large enough to accommodate the

discharge of a potential flashflood.

The volume of a potential debris flow can grow larger while it is going down between the first and

second crossing points with Kennon Road. However, the pool located above the second crossing point

with the road is effective to dissipate the kinetic energy of the flow containing large boulders.

The debris flow can keep flushing down leaving large boulders behind in the pool. Still, it can

keep going down toward the third crossing point with the road while collecting additional materials

on its way. However, an additional pool and sharp bend immediately upstream of the third crossing

point with the road, where the brake is located, are effective to dissipate the kinetic energy of the

flow and to reduce other debris such as drifting woods. It is expected that the synergetic effect of the

debris flow brake with the channel morphology is effective to prevent disasters at the third crossing

point though the size and capacity of the brake are rather small.

The advantages of the target creek mentioned above might however be lost if the material

production at the headwater and the mining site as well as rainfall intensity is large because the

pools no longer have their retarding effect after they are filled with boulders.

Monitoring practices on the creek channel must therefore be directed to the cliff, steep slopes and

pools as well.




23

6. Conclusion and recommendations

As illustrated the above chapters, a Debris-Flow Brake was successfully implemented. The last field

inspection took place on November 24, 2008, and the completion certificate was given to DMI

Construction, the project’s contractor, on November 25. Then the structure was turned over from the

contractor to PWRI on November 27, 2008.

As of December 27, 2008, the deadline of the completion report, the structure was under the

management of PWRI, but was turned over to DPWH on the day of the turn-over ceremony in

January 2009.

PWRI will organize the following seminars aiming at, firstly, promotion of awareness to the high

risks of debris flows and associated disasters, secondly, promotion of debris flow-induced disaster

prevention projects employing the technology demonstrated at the project site on Kennon Road, and

technology transfer of planning, designing and maintenance practices for Debris-Flow Brakes.

The seminars are two folds; one for decision makers and the other for staff in charge of project

implementation in the field.

PWRI will also organize, in cooperation with ADB, a seminar in Tokyo targeting representatives

of debris flow-prone developing countries, funding agencies and international organizations

specialized in risk and disaster management in preferably April, 2009. The points of the seminar are

as follows:

The dehydration technology is effective and efficient to:

1) protect human life, livelihood activities and economic, social and cultural assets from the

threat of devastating debris flows in mountainous regions,

2) raise awareness of decision makers, public and local communities towards both the risk of

and safety from debris-flow discharge,

3) reinforce capacity of local practitioners and implementing agencies in road management,

4) protect roads and networks for transportation, water and power supply, information

transmission from destruction or disruption due to debris-flow disasters,

5) make the most of materials piled up on Debris-Flow Brakes for construction use.

PWRI earnestly hopes that the technology demonstrated in Baguio will be widely used, and that a

hazardless environment will be achieved globally as earlier as possible.

In order to promote the dehydration technology and to encourage decision makers and practitioners

in areas prone to debris flows and associated disasters, it is necessary, firstly, to prepare guidelines

for projecting, planning, designing and maintenance, secondly to give skills to make the most of thetechnology.

Officers and people who are concerned with public safety and infrastructure building are

interested in the technology and have told that it was an eye-opening event to watch a hydraulic

model test on the dehydration technology. They have also agreed that the technology is cost-effective

and cost-efficient. However, few incentives and opportunities for skills development for officers in

charge are provided in most developing countries at the risk of debris flows.




24

Appendix 1




25

Appendix 2

International Centre for Water Hazard and Risk Management (ICHARM)

under the auspices of UNESCO

Public Works Research Institute (PWRI)

1- 6, Minamihara, Tsukuba, Ibaraki, 305-8516 JAPAN

Tel: +81-(0) 29-879-6809 Fax: +81-(0) 29-879-6709

Request for Quotation for a project

In order to implement a project, Testing and Demonstrating a Technology to Cope with

Debrisflows in Mountain Regions in the framework of the TA 6325 – REG Promoting Effective Water

Policies and Practices (Phase 5) Pilot and Demonstration Activity for Philippines funded by Asian

Development Bank, International Center for Water Hazard and Risk Management (ICHARM) under

the auspices of UNESCO and Public Works Research Institute (PWRI), an independent

administrative agency of the government of Japan, would like to invite you to submit, by 17:00 of

August 28, 2008, a proposal for proposed project “Testing and Demonstrating a Technology to Cope

with Debrisflows in Mountain Regions” which is to be implemented at the torrent located at the 241

km site of the Kennon Road in the area of Baguio city. The project will be implemented based on the

following terms of reference (TOR).

Terms of Reference

The Kennon road is very prone to debrisflows which disrupt traffics in case of heavy rainfall. The

project is therefore intended to build a debrisflow breaker which can make a running debrisflow stop

by its dehydration effect. The debrisflow breaker is to be built on the torrent bed and consists of

horizontal screen made of either steel or wood, steel cross beams, retaining walls and a groundsill

made of concrete.

1. The site condition and the initial design are presented in the figures attached

(Figure 1 Planimetric map, Figure 2 Longitudinal profile, Figure 3-1 and 3-2

Cross sectional profile),

2. The screen is devided into three (3) sections, namely Sction A, Section B and

Section C as illustrated in Figure 1.

3. The site of the groundsill falls on the Fall 4 as illustrated in Figure 1 and 2. The

screen in the Section A are put perpendicular to the groundsill and supported by

the groundsill, retaining walls and the cross beam 1. The unit deadweight load

which works in the section A is two (2) ton.

4. The screen in the Section B and C are put perpendicular to the cross beams

and supported by three cross beams and retaining walls. The unit deadweight

load which works in the Section B and C is one (1) ton,




26

5. The size of a slit of the screen is thirty (30) cm in all the sections.

6. The quality and the size of the materials of the screen are determined by the above deadweight

load, but the quality of the material of the Beam 1, 2 and 3 must be steel (SS400).

7. The bearing at which cross beams and the screen are placed must be reinforced

with steel bars of D10, 9.35 mm in diameter,

8. Screen must be fixed to cross beams or retaining walls or the groundsill with steel

bolts in 9.35 mm in diameter and hexagon nats

9. Wood must be treated with preservatives.

10. The contrator is requested to modify the initial design taking into account

microtopography of the torrentbed and slopes in the Section A, B and C. There is

no need to remove base rocks or stable boulders on the bed and slopes. Base

rocks and stable boulders may be incorporated as the part of the groundssill

and retaining walls,

11. The unit Portland cement content is 300 kg and w/c is less than 60 %.

12. Concrete placement works must be carried out in dry conditions, but fresh concrete must be

kept wet until it has hardened.

13. Retaining walls on the left bank are built covering existing dry masonry walls and

natural slopes after removing loose rocks and vegetation.

14. The contractor should be aware of the risks of debrisflow discharge and rock fall at the site and

take proper measures to avoid risks.

15. The structural design prepared based on the initial design and following this TOR shall be

presented to ICHARM for approval before implementation.

16. Boulders on the left side of the torrentbed between Fall 1 and 2 must be moved to

the right side to prevent further erosion of the slope on the right between the Fall 1 and 2.

17. Pipes for drainage 3 cm in diameter and one every 3 m2 are put on the lower part of retaining

walls.

18. Figures of the initial design are attached hereunder,

19. Photographs of the existing dehydration structure are attached hereunder for

reference.

Please submit your proposal not later than 28 August, 2008.

Very truly yours,

Masayuki WATANABE

Coordinator for Disaster Mitigation Research, ICHARM

155-40, Ichinodai, Tsukuba, Ibaraki, 305-0073 JAPAN

Telefax: +81-(0) 29-837-0152: e-mail:[email protected]




27

Appendix3-1




28

Appendix 3-2




29

Appendix 3-3




30

Appendix 3-4

36

Appendix 3-5




31

37

Appendix 3-6




32




33

Appendix 3-7




34

Appendix 4-1 Detail Planimetric Design

40

Appendix 4-2 Detail Structural Design




35




36

Appendix 4-3 Detail Structural Design




37

Appendix 4-4 Cross Sectional Design




38

Appendix 4-5 Detail Cross Sectional Design




39

Appendix 5 Concrete Mix Design




40

Appendix 6 Proposed Work Schedule




41

Appendix 7 Actual Work Schedule




42

Appendix 8 Letter of Completion




43

Appendix 9-1 Structure Completed (1)




46

Appendix 9-4 Structure Completed (4)




48

Appendix 10 Completion Certificate

November 26, 2008

Completion Certificate

Mr. DIONISIO M. INESProject Manager

DMI CONSTRUCTION

#1 Windsor St. cor. Winston Street (Commonwealth Avenue)

East Fairview, Quezon City, Philippines

I will hereby certify that the works mentioned hereunder and launched based on the Contract made

on October 1, 2008 for the Testing and Demonstrating a Technology to Cope with Debris in Mountain

Regions was completed.

Title of the Works

TA 6325-REG: Promoting Effective Water Policies and Practices (Phase 5) -–-Pilot and

Demonstration Activity for Philippines: Testing and Demonstrating a Technology to Cope with

Debrisflows in Mountain Regions

Contract Price US$48,400.

Date of the Contract October 1, 2008

Date of Inauguration October 15, 2008

Term of Works From October 1, 2008 to December 31, 2008

Date of Completion November 24, 2008Date of the Final Inspection November 25, 2008

Very truly yours,

Tadahiko SAKAMOTO

Chief Executive

Public Works Research Institute

1-6 Minamihara, Tsukuba, Ibaraki,305-8516 Japan

CC:Mr.Ian MAKIN, Asian development Bank

Mr.Resito V.DAVID, FCSEC




50

Appenmdix 12 Concrete Strength Test on the 7 days Old Test Piece




51

Appendix 13 Concrete Strength Test on the 20 Days Old Test Piece




Appendix 14

Item No. supporting docum ents rem arks

1-1 D M I Receipt

1-2 D M I Receipt includes $980, the guaranty m oney refund

2-1 PW RI Travel Cost Sheet

Airfare Receipt

B oarding Passes

Rent a car serivece R eceipt

M anila Airport Receipt

2-2 PW RI Travel Cost Sheet

Airfare B ankTransfer Record

B oarding Passes

Rent a car serivece R eceipt

M anila Airport Receipt

Supporting docum ents for the Form 14 (SO E)