murum site visit report

7/31/2019 Murum Site Visit Report

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Consultant Preliminary Design Report

Access to Proposed Site

Murum Dam is one of the other dams constructed in Belaga other than the Bakun Dam. The Dam is

situated about 208 km from Bintulu and can be accessed through Access Road to Bakun. Proper roadconnecting the dam site is yet to complete, however, the dam site can be accessed from a logging

track owned by a logging company. The logging track is approximately 70km in length. The logging

track is well maintained at most sections. At steeper sections, there are concrete pavements at the

outside half of the road to ensure that the logging and material trucks can access the road sites, dam

site and the logging camps in the area. Currently most of the vehicles using the logging track are

heavy trucks (20 tons of loads at average). The logging track does not comply with the JKR road

specifications. The reserve is too small and there is no proper drainage serving the road.

Nevertheless, the road still serve its propose as means of transportation of material and logs into

the dam site and its surrounding area.

Considering its distance, the journey should take 3 hours at maximum, but due to the poor

conditions of the existing Bintulu-Bakun Road and the existing logging track, it takes about 4 hours

and 45 minutes for the Consultant to reach the dam site.

Existing Access to Murum Site

The proposed site for access road to ecological power house and to the water intake is a 30 minutes

journey through the logging track from each other. The proposed site for ecological power house

access road is at the dam site while the proposed site for water intake access road is 30 minutes

away from the ecological power house.

Generally the terrain in the area is very rough and blasting is maybe required for earthworks due to

the type of soil in that area. There are limestone deposits and hard rocks such as shale found in that

area. A number of rock quarries found around the Murum dam site strengthen this fact.

Logging track (70km)


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The Condition of Soil on Site

Access Road to the Ecological Power House

The scope of work is to connect the top of the dam crest weir and the ecological powerhouse which

is on the lower site of the dam. From SEB site office, the proposed site can be accessed through theconcrete road constructed under the Murum Dam Access Road Package to some extent. Passing the

contract limit, there is a gravel road connecting the contract limit and the dam site.

The existing road is basically an ascending and descending road at about 1.5km in length, from the

contract limit of the Murum Dam Access Road Package to the Dam Crest and the ecological

powerhouse. Due to the condition of the terrain, the existing road is laid most probably to follow the

existing contour at that area. The conditions of the road at the dam site are quite poor and urgently

needs repairs and upgrade. Poor drainage, overloading and poor subgrade may be some of the

causes of the roads to be badly damaged. The grades of the existing road may need redesign if it is

too steep. The rolling terrain is one of the challenges needs to be considered if there is a need toregrade the existing road.

On the safety side, there are no permanent safety signs and guardrails installed. Therefore safety

aspects of the road are needed to be included in this contract.

Anyways, the proposed alignment should be not much different from the existing road to reduce the

construction costs. Proposing a different alignment would incur extra costs on earthworks and even

bridgeworks.


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The Proposed Beginning of the Access Road to Dam Crest Weir and the Ecological Powerhouse

The Limit of Contract for the Murum Dam Access Road Package


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The Current Condition of the existing Access Road 1 (Gravel Road)

The Current Condition of the existing Access Road 2 (Gravel Road). Note: There are some services at

the roadside which requires relocation.


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The Dam Crest Weir under construction


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The Elevation View of the Existing Road to Ecological Powerhouse

The current road condition Surface spalling of the concrete pavement and improper gradient of

alignment

The Dam Crest Weir

The Ecological Powerhouse

Material Plants and

Laboratory which may

be affected by the

Construction


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Severe loss of pavement surface texture

The challenges may be faced during the design and construction phase of this section are:-

1) Condition of soil on site. It will be a challenge to cut the existing hill because the soil at thatarea are mostly rock. The consultant needs to choose the alignment and gradient carefullyto minimise rock blasting which would increase the cost. Choosing the right gradient and the

right alignment will be most challenging as the difference of the height between the dam

crest weir and the ecological powerhouse is more than 100m high.

2) The Contractor needs to aware that they will face a problem in terms of manpower becauseat the time of execution of the project, there will be a lot of development in Bintulu and

areas nearby.

3) The local authority for approving the road alignment needs confirmation so that the roaddesigned will comply with their requirements.

4) To provide temporary access to the existing dam site and the ecological powerhouse site.The construction of the ecological powerhouse and the access road may happen

simultaneously. These temporary access roads are also needed so that material can be

delivered to and from the material plant and laboratory which were located nearby the

proposed site. There is other access to that area but it will take longer time to drive through

that road from SEB office to the Dam Site.

5) It is recommended for the Client to appoint the contractor doing the projects nearby theproposed site. This can save costs and reduce mobilization time.

6) Coordination between the contractor that will be appointed to construct the road and theDam contractor is essential to prevent any major problems which be delaying the progress

of both sites.


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Access Road to the Water Intake, Surge Tank and the Proposed Boat Ramp

The distance of the proposed site is a 30 minute drive through the logging track from the ecological

powerhouse. This site requires the existing access road to be upgraded into a proper concrete road

which complies with JKR Standard Specifications. The access road is about 3.7km long. About 0.6 km

of the road which connects the logging track and the old access has been constructed and

completed. The new road is 5m width and the design complies with the JKR Standard specifications.

There cascading r.c drains at one side off the road (hillside). Design standard applied to the new road

can be considered as sub-standard R3, where the width of pavement and the shoulder at the side

facing the drain is reduced to suit the site condition. At this site also, there will be a proposed ramp

for the towing of the boats.

The access road to water intake begins at the new stretch of the road which is 0.6km long. The new

road is actually a diversion from an earlier alignment because the new access road to Murum Dam

Site will be cutting through the old road. The turning curves are quite sharp at some of the sections

and the gradient are quite steep at some sections. The existing path is winding and the most

probable reason for this is the alignment design to follow the existing contour. This method of

alignment design is used to reduce cost of earthworks. The Consultant would like to try to make the

most direct alignment connecting the water intake and the surge tank while reducing the cost of

earthworks as much as possible.

The challenges may be faced during the design and construction phase of this section are:-

1) Condition of soil on site. It will be a challenge to cut the existing hill because the soil at that areaare mostly rock. The consultant needs to choose the alignment and gradient carefully to

minimise rock blasting which would increase the cost. Most probably, the alignment will sit onthe top of the current alignment to prevent unnecessary cut and fill works.

2) Existing quarry at chainage 2400 of the road may cause instability to the existing road formationthere. New alignment away from the quarry for that particular section needs to be considered.

3) There are also small pipelines found on the roadside. Eventhough it is only temporary, thewater pipe needs to be maintained and relocated the road upgrading works.

4) The sight distance of the existing road is bad especially at the sharp curves. It will be a challengeto the Consultant to provide curve with a larger radius at these sections. Other alternatives can

be considered are to put signages or mirrors at appropriate places. A new alignment at these

sections would be the best alternative for these sections.

5) A larger road corridor will need to be constructed on the existing road to provide enough spacefor 110kv transmission line. At such a place with space constraint, and with a tight contract

budget, the Consultant will look for methods of constructing wider formation at these type of

areas in the later stage.

6) Coordination between the contractor that will be appointed to construct the road and the Damcontractor is essential to prevent any major problems which be delaying the progress of both

sites.


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Joint stepping on the concrete pavement at Chainage 700m of the existing access road

The New Access Road Section to Water Intake and Surge Tank (Phase 1)


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The Existing Road Section to the Surge Tank

The Water Intake Site


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The Boat Ramp Site 1

The Boat Ramp Site 2


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Consultants approach to the Design

The obvious challenge in this project is to design the alignment with lesser cost impact in the

earthworks. Other than that, the other challenge is to provide proper temporary diversion that will

ensure the construction of the dam will go smoothly during the road construction period. Other than

providing temporary diversion, the sequence of construction and upgrading works of the road also

needs to be considered.

For the earthworks, there will be a provision of blasting works in some of the sections of the roads

where more corridor space is needed for the 110 kv transmission line which will be placed on the

roadside in the future. From our professional opinion, there will be more cut works than fill. The

Consultant also assumed that there will be a need to reconstruct the road from its subgrade at some

sections of the road. Standard type of formation as per JKR and REAM Specifications will be used for

this design. The proposed formation cross sections are attached at the end of this report. The

Consultant would try to minimise the blasting works needed to reduce the costs and to avoid

problems which may be caused by the blasting works in the future.

Proper drainage is one of the main factors that affect the durability of the road formation thus the

service life of the road. Stagnant waters may seep in to the formation and damage it from inside. At

this area where it is mountainous, it can affect the slope stability where the road alignment is laid

on. The Consultant would recommend concrete drainage as it does better job to transport runoffs

compared to earth drain.

The design also will consider probable traffic loads for the road which is most probably trucks

weighting 15 tons at max and more variable types of vehicles after the completion of Dam. The

targeted design life for the road is approximately 40 years. With safety of the road users andgeometric conditions of the road, the Consultant will adopt 30km/h for the speed, but will design

the road for vehicles moving at 50km/h. At some point where the maximum allowable gradient as

specified in the JKR Specifications cannot be complied, the design will adopt a lesser gradient than

the gradient used for the existing road.

murum site visit report

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