INDUSTRIAL CASE STUDY : EXCAVATION & DEWATERING TECHNOLOGY

INDUSTRIAL CASE STUDY : EXCAVATION & DEWATERING TECHNOLOGY

KLANG VALLEY MRT (KVMRT) LECTURER: Prof. Madya Dr. Chan Chee Ming Ts. Dr. Tuan Noor Hasanah Binti Tuan Ismail

BNC31803 SITE INVESTIGATION GROUP 2

SUPERVISOR: Assoc Prof Ir Dr Siti Noor Linda Taib

Group Members

NIK RAHIMAN BIN NIK AZHAR CN190213

MUHAMMAD HAZMAN SHAFIQ BIN ROSZANIHAR CN190060

Group Members

NURUL ALEYA BINTI ROSTAM AFFANDY AN190075

NOR IMAN FATIHAH SOIFUL BAHRI AN190140

1 Introduction Project Background

Problem Statement

The Klang Valley Mass Rapid Transit (KVMRT) Sungai Buloh - Deep excavation is defined as a soil excavation that is deeper than Kajang Line project is Malaysia's first MRT project. The KVMRT 15 feet. Open excavation and reserved deep excavation are the Project would span 51 kilometres and include 31 passenger stops. two forms of excavation. Deep excavations are required for The project includes the construction of 9.5km long twin tunnels optimum space use. The KVMRT project consists of subterranean from Semantan to Maluri, as well as 7 subway stations and stations located in the city region, with excavation depths ranging accompanying infrastructure such as portals, ventilation shafts, from 20m to 32m in limestone formation. TRX Station is the escape shafts, and crossovers between the Klang Valley and deepest station, with a maximum excavation depth of 45 metres Kuala Lumpur metropolitan districts. This research focuses on below earth, and serves as one of the subterranean interchange the deep excavation work for underground stations as well as the stations for the KVMRT Line 2 from Sg. Buloh to Serdang and groundwater control for this construction project.

Putrajaya (SSP Line). The most typical issues encountered during excavation operations are the collapse of the side trench and water pouring through the trench's side walls. Other issues related with deep excavation include dewatering, retaining wall construction, hauling out used piles, and excessive excavation.

2 Problem Analysis Work procedure for excavation at construction site involves method involves excavating down to and exposing the existing pipe understanding of centre line and excavation drawings, setting out so that it can be repaired or replaced and then backfilled. of plan on ground, excavation of soil and removal of excess soil.

Quality checks such as recording ground level and marking of reference points should be done. Excavation is the process of moving earth, rock or other materials with tools, equipment, or explosives. It is also including trenching, wall shafts, tunnelling and underground. It is the preliminary activity of the construction project. Choosing the right excavation method inevitably considers

If open cut trench excavation is done in unpaved areas, the excavation can be backfilled with soil and surface vegetation, which is restored by sowing or turf. If open trench excavation is under the pavement, the existing pavement should be cut and removed, the excavation and pavement filled with granular backfilling should be replaced, and the pipe should be repaired or replaced at the end.

many factors, including construction budget, allowable construction It was divided into two major types including sloped full open cut time, existence of adjacent excavation, availability of construction and cantilever full open cut. The former is assumed to be machinery, area of construction site, condition of adjacent building, economical since the side of excavation would be sloped and does type of foundation of adjacent building, etc. there are few not need any support to held foundation wall. However, if the slope commonly used methods for deep excavation. is considerably gentle or the excavation is largely deep, it will be 2.1 Types of Excavation 2.1.1 Open Cut Trench Excavation Open cut, as the name implies, is a method of pipeline installation that requires the surface to be cut to the depth required to install the pipeline. This is a traditional method and is still widespread and is widely used for the installation od side sewers and for the repair or replacement of main and branch sewers. The open cut

costly. The latter need retaining wall to support foundation wall soil and prevent collapse of the foundation wall but it neither require backing nor slopes. Therefore, it cannot categorically be claimed that which method is more cost effect. The economically method may be distinguished based on analysis, design, and evaluation results.

2 Problem Analysis 2.1.2

Braced Excavation

2.1.3

Anchored Excavation

Braced excavation is a method where deep excavations with In this method, the vertical shoring elements made in the anchors straight vertical faces are laterally supported by a sheeting and are installed to counter earth pressure. The configuration and bracing system until the structure is built. Bracing system consist components of the anchor drilling technology. The constrained part of wale, strut, centre posts, end braces, and corner braces. Earth of the anchor provides a fixing force that acts against earth pressure transfer to horizontal; struts through wale, and the pressure, while the unconstrained part of the fixed part transfers purpose of corner and end braces is to reduce wale span without the pressure to the anchor head. Resistance is provided against the increasing strut number. Centre posts prevent the failure of struts ground behind the vertical shoring elements by anchoring the due to their own weight. Though struts and centre posts may horizontal shoring element. obstruct the excavation process, the braced excavation method is the most commonly used method, applicable to any excavation depth or width. Since the length of a single strut is finite, it may require splicing several struts together to span the width, as it is difficult to keep the spliced struts aligned and misalignment may result in deficiency or lateral resistance. Some methods are vertical timber sheeting, shoring, steel sheet piling, soldier beams and tiebacks. The design of braced cut involves two distinct but

The bonded portions of anchors generate an anchoring force that will hold up against earth loads. The unbounded ones will move pressure to the anchor’s head that then transfer loads to your retaining walls. The anchoring force essential for construction is primarily dependent on the soil strength. Anchoring takes minimal time but cannot be used in deep excavations and granular or clay soils with high water tables.

interrelated features, namely, the stability of excavation, ground Anchor supported excavation method can be collected under two movement, control of water into the excavation, effect of adjoining heading. structures and so on. These structures cannot be removed later, but they may or may not be structurally important, except to provide temporary lateral support.

•

Passive anchored excavation method

•

Prestressed anchor excavation method

2 Problem Analysis 2.1.4

Island Excavation

2.1.5

Top-down Construction

Island excavation method can be thought of as a combination of In the top-down excavation method, the excavation progresses from many

excavation

methods,

including

internally

supported the top of the land to the foundation. The excavation process is

excavation method and open excavation method. To apply this done gradually. A vertical shoring element is constructed. The excavation method, a larger excavation area is required than other vertical shoring elements made for lateral support also serve as the methods. The structure to be constructed should be designed carrier element of the building. Beams and floors made for the according to the formation of cold joints. In this method, excavate building also serve as horizontal support elements. Contrary to the the centre of the excavation area and place the excavated material bottom-up construction method, the top-down construction method near the retaining wall to create an embankment. After that, most is to erect moulds and construct floor slabs right after each of the structures will be built in the centre of the excavation. The excavation. The floor slab are permanent structures, which replace slope is then excavated, and struts will be placed between retaining temporary steel struts in the braced excavation method to wall and the main structure. Finally, the struts are removed, and counteract the earth pressure from the back of the retaining wall. the rest of the structure will be constructed. Sometimes, it might be Construction process order include retaining wall construction, pile required to use anchored or braced technique to removed slopes soil construction under column of superstructure, placing columns on material, specifically when the excavation is too deep. This method, piles, and installing formwork for the first slab at the top then compared to the internal excavation method, it required less other slabs would be constructed after each excavation this shoring elements, therefore less cost and labour. The building and technique would need short construction time, but the cost is shoring element connections, which are not made carefully, may higher compared to other method. The floor slabs used in the topcause problems during the installation and dismantling phase. This down construction method are heavier than the stee struts used in method that cannot be preferred in applications where excavation, conventional excavation methods. In addition, the superstructure, shoring and superstructure works can be applied together and which is constructed simultaneously during excavation, puts more there is not enough space to create bevelled steps in front of the weight on the column. Thus, the bearing capacity of the column shoring system.

must be considered. .

2 Problem Analysis 2.2

Groundwater Management

2.2.1

Sump Pumping

Based on the case study that we have obtain, there were few of This method allows the groundwater to seep into the excavation, support systems that were suitable for our excavation process. where it is collected in sumps and pumped away robust solidsmethod that we were used are braced excavation method. But in handling pumps. This method is applicable to relatively shallow certain place need a temporary ground anchor excavation because excavation. This type of groundwater control can be inexpensive, it has loads that cannot be supported by braced systems. The but ground loss as well as excessive seepage can be time consuming anchor consists of a few pairs of strands with different unit lengths. and expensive to deal with. Pre-drainage methods may be used for It is essential to note that groundwater control is essential, and it situations where sump pumping may pose a threat to the is one of the most important criteria to be considered in excavation instability of the ground or adjacent structures. Sump pumping can works. Groundwater drawdown may lead to excessive ground be very effective and economic method to modestly reduce the settlement

and

occurrences

of

sinkholes

surrounding

the liquid in a sump, especially in favourable ground conditions such as

excavation. Potential risk of excess groundwater intrusion into the well-graded course soils. drilling pit should be assessed, especially if limestone is formed.

Groundwater causes extreme geotechnical problems in excavations such as sand running for most of construction project such as tunnelling. So, issues caused by groundwater would increase construction budget and extend construction time unless the groundwater is properly controlled which is the root cause of the problems. Controlling groundwater during excavation is extremely important in the construction industry. There are various dewatering and groundwater control method used on major construction sites.

Advantages Effective water removal More reliable than other waterproofing treatment Able to handle major leaks

Disadvantages Electricity required Possible leading to loss of fines and instability Generate silt or sediment-laden discharge water, causing environmental problems.

2 Problem Analysis 2.2.2

Wellpoint Systems

Wellpoint systems are used to lower groundwater levels to provide stable working conditions. They consist of a series of small diameter wells that are connected by header pipe to a wellpoint pump. The pump creates a vacuum in the header pipe drawing water up from the ground. Wellpoints are typically installed along or around excavation. The height to which water can be drawn by

depth of excavation more than 16m depth. This hence demands higher rate of pumping for dewatering. This is mainly employed for the ground preparation for the construction of tunnels, dams, powerhouses, shafts, and locks. This method consists of several bored wells, each using a submersible borehole pump. As water pumped from each well, the groundwater is lowered creating a come of depression.

vacuum in this way is approximately 6 metres. To functions at greater depths, well points can be installed in stages as the excavation proceeds. The riser is surrounded by a coarse sand filter in order to facilitate the flow of water towards the well points.

Wellpoint systems are particularly suited to dewatering for shallow foundations and excavations, so they are often used for pipeline trench work. A wellpoint system can be installed quickly in most ground conditions, and they are easy to maintain.

2.2.3

Deep well systems

Deep well systems are dewatering methods used to remove the water from previous sand or rocks formations beneath the excavations. This method can also be employed to remove the artesian pressure of the ground are under consideration. The method of deep well dewatering is more suitable in areas where deep excavations are performed. This system is suitable when the

Advantages No limits on drawdown Fewer wells required than well system

Disadvantages Expensive to install

2 Problem Analysis 2.2.4

Ejector systems

2.2.5

Collector wells

Ejector well systems work on the same principle as well point A collector well is a horizontal radial well used to extract water system but allow water to be drawn from deeper in the ground. An from an aquifer with induced infiltration from a surface water ejector dewatering system consists of an array of wells pumped by source like river or lake. Collector wells consists of a central jet pumps installed at the base of each well up to depths of 150 concrete shaft or caisson equipped with horizontal screens metres. This method suitable for low permeability soils, very silty radiating out into the water bearing sediments. Water id drawn sands, silts, or clays by reducing pore water pressure. The ejector into the central caisson through these horizontal screens or laterals or eductor system is based on wells that are drilled to lower the where it collects and is pumped to the ground surface. This method groundwater level to provide stable working conditions. Ejector use is suitable for high permeability sands and gravels. However, the air within the wells to produce a vacuum to draw water out of the collector well system is expensive to install. The advantages of soil. The advantages of ejector system:

collector well:

•

They are flexible in level and layout

•

•

Stable in operation

effectively dewater a large area.

•

Able to run dry without damage

•

•

Not limited by depth

than equivalent vertical wells and thus produce significantly

•

Bet in low yielding wells

•

Energy intensive

Relatively few wells could produce large flow rates to

Collector wells distribute drawdown over a larger area

smaller maximum drawdown.

3 Modern Tool Usage 3.1

Selection of Excavation Support System & directly ensure there are no water will be disturbing in the

Dewatering Method Suitable for The Field Conditions Based on the study case that being conducted, there are several

excavation site. It also doesn’t need more space to install it which will not use space and disturb the surrounding.

factors that need to be consider while choosing excavation support 3.1.2 system and dewatering method. One of the factors that need to be review and consider as a main issue or problem is the site condition and soil properties. In this case study that are construct TRX station, the site condition is being conduct in the middle of the town which is Kuala Lumpur, and the problem that arise by doing the site investigation is there are limestone detected. From the listing of excavation support and dewatering method above the most suitable use for this method is using sheet pile method for excavation part and deep well for dewatering method.

3.1.1

Excavation Support System

The selection of the excavation support system is sheet pile and being supported by temporary anchor system, because it was designed to withstand more load for it use in deep excavation, the installation is easy and the cost is affordable comparing to other method, by using the sheet pile, it can avoid the limestone from moving and cause any accident such as soil settlement that will endanger nearest buildings. The sheet pile also watertight, this

Dewatering Method

The dewatering method being used is deep well system, this system is suitable when the depth of excavation more than 16 m depth, so it fulfils the condition for the deep excavation. Highly effective for sand, gravels, fissured rocks. Wells are drilled at wide spacing of 10m to 60 m between wells to from a ring around the outside of the excavation. Deep well system is normally suited to relatively deep excavations, where permeability is between moderate which is sands to high which is gravel. It suitable with the site and soil condition for the case study being conduct and by using more pump the water ground level can be controlled. When long-term dewatering is required means long term construction, this approach is more appropriate. As a result, this method may be used for massive excavations in a range of ground conditions.

These methods can assist offer under-drainage of the less permeability underlying soil into the pumped permeable layer.

3 Modern Tool Usage 3.2

Excavation Support System: Sheet Pile

3.2.1 Advantage of Sheet Pile

In the construction sector, sheet piling is used to create temporary • 1. Sheet piles are recyclable and reusable. and permanent barriers. Sheet piling is used to support • 2. Piles can come in a wide range of lengths, size, and steel options. excavations and retain soil. It is normally put in a certain order along the perimeter of an excavation. They create a wall for • 3. They can be used for temporary and permanent structures. permanent or temporary ground support when stacked together, • 4. They can be installed using silent and vibration-free methods. with anchors to offer extra lateral support. Permanent sheet piles are designed to last a long time and are erected using vibratory • 5. The work is neat, clean, and creates no spoil arisings. The supervision of work on-site can be reduced, and minimal storage hammers. It can also be forced into the ground hydraulically, space is required. depend on the ground type. These walls are then arranged together to form a wall. These piles are made of steel and are • 6. Sheet piling is a more cost effective and quicker installation than contiguous or secant walls. designed to last a long time. They can be hydraulically pushed into place if the soil conditions are too hard or dense. Although steel is • 7. Cofferdams can be constructed in almost any desired shape, however, for practical and economy reasons, most cofferdams usually used for sheet piling, other materials are also commonly are either rectangular or circular. used. The design of the pile and the strength and stability of the • 8. Sheet piles can provide a close-fitting joint to form an sheet are also known to be determined by the material's shape. effective water seal.

Temporary walls are usually used for confined spaces to prevent cave-ins. Then, sheet piling is commonly used as a permanent wall • 9. They have a long life above and below water, making them advantageous for marine and coastal projects. material for homes and offices. This material is also used to • 10. Anchored sheet piled walls can provide even more flexibility prevent flooding in areas near shorelines. for installation purposes.

3 Modern Tool Usage 3.2.2

Limitation of Sheet Pile

1. Lower stiffness than column pile or diaphragm walls.

means of addition of successive installments of sheets. It forms a barrier that stops the dirt from getting too close to the building.

2. Susceptible to settlement during striking or dismantling in sandy ground.

3. Not easy to strike pile into hard soils.

4. A lot of noise is cause during striking 5. Leaks cannot be complexly avoided and sealing and grouting are probably necessary if leak occur.

3.2.3

Countermeasure of the Limitation

Figure 3.1 The arrangement and installation of sheet pile

Based on the limitation that being list to counter this problem for the solution given is to use machineries with a lot of power to forcedly push the sheet pile so it will be installed properly. And for noise while striking, it is advised to use noise concealing barrier to reduce the noise that it makes while striking.

3.2.4

Sheet Pile Technology Component

Sheet piles are thin piles, made of plates of concrete, timber, or steel, driven into the ground for either separating members or for stopping seepage of water. It is not mean for carrying any vertical load It is driven into the ground with the help of suitable pile during equipment and their height is increased while driving by

Figure 3.2 Section of sheet pile (a) U pile (b) Z pile and (C) straight pile

3 Modern Tool Usage 3.2.5

Installation of Sheet Pile

3.2.5.2

Panel Driving Combined with Staggered

Steel sheet piles can be set in the ground in several ways. The There are two approaches. Except for the staggered sheet piles major issues to consider are soil conditions, sheet piling section pushed, the principle is identical to the preceding one. Reinforcing and length, drive equipment, permanent vs. temporary wall, the tops of some of the piles increases performance in particularly visible wall, installation tolerances, interlock sealing methods compact soils, although normally only every other pile is used, and so on. As a reminder, sheet piles may be driven into any reinforced. The key benefit is that it performs better in highly type of soil except rock. When selecting an installation approach compact soils. and pile driving equipment, keep in mind the overall system, as mentioned before. A successful piling project may also be

3.2.5.3

Pitch and Drive

dependent on a comprehensive soil study. In normal installation The idea is straightforward that each sheet pile is threaded and operations, vibratory hammers, impact hammers, presses, or a driven to its final depth. As a result, it is both quick and combination of these driving devices are employed. inexpensive. When strict installation tolerances are not a big 3.2.5.1

Panel Driving

problem, sheet piles are relatively short, leaning is not a predicted issue, soil layers are not too packed, and so on, it may be

It is recommended for permanent walls such as subterranean appropriate. parking garages and basements, interlocks with a sealing system, and soils where tilting is expected, such as particularly soft soils.

3.3.5.4

Driving Assistance

The main benefit is that it is easier to attain the requisite When using heavy equipment, or to decrease vibrations and noise, tolerances and prevent sheet pile tilting. While the major or in highly compact soils, such as waterjetting, pre-drilling or predrawback is that the method takes longer for example handling augering, or blasting, driving assistance should be considered. and threading the piles, it also necessitates a longer crane boom for pile lifting.

3 Modern Tool Usage 3.3

Water Management System: Deep Well System

3.3.1

Arrangement of Deep Well System

When the excavation depth surpasses the maximum restrictions The system for dewatering deep wells is like that for commercial for all dewatering method system and a substantial amount of water wells. A screen with a diameter of 6 to 4 inches and a length water must be retrieved, deep well dewatering systems are of up to 300 feet will be used in these systems. This configuration commonly employed. They're perfect for keeping water out of aids in the prevention of foundation material intrusion into the construction trenches, allowing workers to work in dry, stable well. The addition of a filter also aids in increasing yield. The deep circumstances. If space is restricted, a deep well system might be well systems can be used in conjunction with the deep wells to employed, as deep wells can be located distant from the building dewater small deep excavations. This is used in tunnels, sunk area. This type of deep well system is suitable for the case study caissons, shafts, and regions with fine-grained sand or pervious conducted because the excavation for TRX station is large scale stratified soils. A vacuum is created in the environment when the excavation and have high ground water level, it also recorded have hydraulic gradient to the well increases due to the application of limestone in the soil. It is essential to note that groundwater vacuum. This phenomenon prevents seepage into the excavation control is essential and it is one of the important criteria to be from the perched water. considered in excavation works. Groundwater drawdown may lead to excessive ground settlement and occurrences of sinkholes surrounding

the

excavation.

Potential

risk

of

excessive

groundwater ingress into excavation pit shall be evaluated especially in limestone formation. Natural features of solution channel with cavities and highly fractured limestone connected to excavation pit may cause disastrous flooding inside the excavation pit.

Figure 7.1 The use of deep well with vacuum systems to dewater a shaft over a stratified ground material.

3 Modern Tool Usage A suitable well depth is required to give a sufficient wetted area of 3.3.3 Limitations of Deep Well input in the aquifer. The pump should be installed at a level in the well that allows the water to circulate and keep the well cold. The

• Installation expenditures per well are rather significant.

spacing of the wells is determined by the site plan. However, the • Because individual pumps span a limited range of flow and discharge head, equipment flexibility is limited. most frequent separation is 10 to 30 metres. The well's deepening causes drawdown in some locations. Special attention and effort • Because pumps are electrically driven, both duty and backup power supply are necessary for reliability. must be used to ensure that the nearby structures do not settle as the drawdown increases. The usage of well screens can help 3.3.4 Countermeasure of the Limitation gravity flow of water into the well without damaging the unconsolidated stratum that is being pumped. The material utilised is determined by the sort of task performed. Steel or plastic might be utilised depending on the sort of task performed.

Corrosion cells will form if various metals are used.

3.3.2 Advantage of Deep Well • Only the depth of the well and the stratification of the soil limit the amount of water that may be drawn down.

• Deep layers might give pressure alleviation.

• Wells can be situated away from working areas for example, at the top of batters.

• Wells are often erected at a reasonably wide spacing to reduce surface access constraints.

Based on the limitation that being list to counter this problem for the solution given is by reducing the use of pump, then the cost also will directly be being reduced, but make sure the pump is adequate and not disturbing or delay excavation process.

3 Modern Tool Usage Operation of Deep Well System for Dewatering • The amount of drawdown necessary for the well is first determined. This will aid in the excavation's geometry. of Excavations • The amount of water that enters the excavation is calculated.

Deep well dewatering necessitates the use of three-phase Flow nets can be used to measure inflow in wide regions. This can also be used to check for the possibility of piping or boiling generators for power. It is advised to have an automated cut-in during high intake velocity. generator in case of a power outage for long-term operations. This 3.3.5

device is deemed a need for insurance purposes.

• The trial well's yield and wetted length are computed.

While a limited time frame is required for corrective action. Level- • The number of wells and their spacing are determined. If any zone interaction is discovered for wells with fewer than 20m monitoring electrodes are put at maximum and minimum levels centres, it will be reported. within the borehole to maintain the drawdown and prevent the • The filter pack and screen slots are intended to prevent the pump from drying up. A good and thorough manual adjustment of aquifer from being drained into the well. the surface recharge valve will aid in maintaining a constant rate of pumping. Top drive vertical shaft pumps and submersible • The well's entrance velocity is measured. electric pumps are ideal choices for big diameter wells.

• The pump size is tested to ensure that it is compatible with the screen or liner.

• It is necessary to give adequate working area for side slopes and excavation.

3.3.6

Design of Deep Well Dewatering System

It is very important to determine early the distance, the drawdown and the time results based on the pumping tests carried out. These are several basic steps that are involved in relation with the design of deep well dewatering systems are

• The analyses are repeated until the best design is found.

3 Modern Tool Usage 3.4

Proposal of operational efficiency & good

practices to ensure optimized productivity & safety

machine in excavation should be reduce the risk of them falling on people.

• A barrier should be introduced around the excavation area It is an essential precaution step to avoid other people from falling into the excavation. ability to deliver projects or services at the lowest possible cost Essentially, operational efficiency in construction refers to the

while maintaining work quality, productivity, and profit. Good • All machinery should be kept completely out of the excavation practices in construction are the standard and planned practices area for safety reasons as it will not endanger the stability of the slope. followed in the construction industry to ensure optimal outcome and profit. In this case study that is TRX construction, the sites in • Underground services or utilities should be mark so the workers can get clear view and avoided any accident from happen. urban areas and the soil conditions that being detected has a limestone. Given the city infrastructure's limited space, deep • The soil at KTX station is limestone, so the process of installing sheet pile must be carefully excavations are necessitated by the need for the protection of existing objects in the excavation vicinities, and large loads • Ensuring that adequate pumping equipment is available so that transmitted from the ground and from the structure. To ensure the any water that seeps into the excavation can be easily pumped out to a safe location. success of this project and optimal productivity and safety, good practices and operational efficiency should be considered.

3.4.1 system

Excavation support system and Dewatering

• Adequate dewatering arrangements should be made because the excavation goes below the ground water table.

• In appropriate circumstances, most soil and rock formations can be injected with grouts to reduce permeability and increase The deep excavation and dewatering method, which causes strength. significant ground settlement behind the retaining wall in soft ground, causing damage and even structural collapse to buildings • Ensuring the dewatering pump is installed properly within its influence zone and delaying of the project progress.

• Ensuring the installation of the support system is properly cause it sheet pile so any leak is crucial • Various of soil testing to get the info of the soils as much as possible so the support excavation can be decided. By choosing the right excavation support system the material, workers and

4 Project Management & Finance 4.0

Project Management & Finance

4.1

Impact of Used Method in Excavation Work

Sheet piling has been the key option to the engineers for the excavation works and retaining wall, just like how we proceed to use the method for the excavation work. However, sheet piling has their own impact to the environment, includes settlement to the adjacent area. High vibration level produced in the installation process of the sheet pile gives effects to the surrounding ground, making vertical movement then affects the structure of the buildings existed in the construction area. Therefore, it is advised that vibration monitoring can be a way in order to avoid the vibration produced from affecting the surrounding settlement.

Sheet piles installed are also exposed to the groundwater and any other elements that are able to cause corrosion to the steel. This could be dangerous to the available pipeline or gas line as they contaminate the piping then the water and gas in it. Contaminated water that will be used by the people will be dangerous and gives effects to the human health. While sheet piling gives enough nuisance to the environment, open cut excavation method regardless affects the environment because of their carbon footprints exposed after trench excavation. The open cut excavation uses a great amount of ground to be excavated from the site in order to gain access to the underground, therefore more greenhouse gas emission happens as the greenhouse gas emission increases according to the amount of ground excavated, especially on rock soils. Most engineers in construction industries and contractors are doing their best in keeping all projects to be conducted in costeffective with optimum design. However, sheet piling is not suitable for those planned to keep up the low-cost construction. Most sheet

piling method used is for temporary work and not suitable to put as in permanent construction. Therefore, the costs in preparing sheet pile retaining wall is huge and not worth it compared to their usage for a single project in addition the side effects they produce along the process. It would be great if the sheet pile is reusable for contractors to use in other projects.In order to operate the open cut excavation process, the whole site must be restricted from the outsider such as public citizen. As a result, certain public places are not accessible by the community as example the roadway or walkway. Such blockage in the middle of people way would cause traffic jam especially at peak hours, includes hazard treat to the passerby as the damaged road really affecting peoples’ drives. Other than that, the noise and vibration emitted from the excavation work interrupts residents from nearby area to have a safe and sound house environment. All these trouble people had to face for a long timeframe will have the community to file a complaint to the responsible party and action will be taken on the engineers involved. Echo barrier is important to lower the level of noise emitted by the machines.

4 Project Management & Finance 4.2

Impact of Used Method in Water Management

Deep well dewatering system really helps in penetrates the groundwater out from under the foundation. Unfortunately, it also contributes to the negative impact in environment such as electrical power usage for the operation of deep well system. Electrical power is a non-renewable energy that are largely consumed by every day and likely to finish up one day. The necessity of electrical power in the deep well system is such a waste. Therefore, the plans to splitter bladder for the activation of deep well system could help reduces electrical power usage daily. Pumping out groundwater also reduces the level of groundwater table, causing the other typical well to not have water reaching the ground. Loss of groundwater also causes ground settlement in the area nearby. Reduced moisture of soil underground because of lost groundwater causing less supportive force of the soil upwards hence affecting the ground on the surface.

The installation of the deep well system also requires a large amount of money by the contractors, even though it only covers a limited range of flow and discharge head per equipment. They costs a lot because of high quality material used in order to submerged in the water must be stainless steel to prevent metal corrosion. So, estimation work and planning before continuing the installation is important to prevent large money spending. In social aspects, the simple features might get people confused with broken waterpipe.

This may cause disturbance to the well work system if they try to stop the water from flowing. We might need to put up a signage to give warnings to the people.

4.3 Efficiency of Method Used on Improvement in Excavation Work Vibration monitoring is a process of analyzing the vibration happening underground. The purpose of the method of vibration monitoring is to control any geotechnical works that cause vibrations, so they do not affect nearby area. There are special equipment and procedure in this method, but the main idea in using vibration monitoring is able to change the frequency of vibrations emitted by the process of installing sheet piles. It is found that a small changes in vibration frequency could avoid resonance, hence giving less impact to the ground settlement in the area. This method of improvement is chosen because of their low cost of work where they only need to buy the vibrating monitor equipment and could prevent from more accidents occurring at the construction site as the activity conducted has not involving heavy machinery.

Relevant to the cost spending on the sheet piles, temporary construction needed the parties involved to get the sheet piles just to use them for a temporary time. Therefore, sheet piles can be reusable in many other projects if the contractors are handling many projects in a long time or they have company warehouse to store the sheet piles so they could be reused in the other time project. In case some of the contractors are still new to the industries and do not have enough to buy a whole pile set or warehouse to store them, there are sheet pile rental service offered by the manufacturer or traders for the convenience of not pull-out huge cost. Not only they can save money, but they will also help more business to expend and helps in economy growth for the country.

4 Project Management & Finance Lastly, in order to keep the social well-being, giving alternatives road to the vehicles is encouraged for keeping the road user from hazardous despite less money will be needed in finding the alternative road. Contractors may deal with ministry of road in order to fully close the road in process of construction so there will be no high traffic around the area. A safe and sound environment also could be created by using echo barriers where it covers the source of the sound and prevent them from emit to the surrounding atmosphere. Hence, the heavy sound could be lowered and not disturbing the community area with low-cost extra layer of sound protection. It is very easy to carry thus portable to reuse and bring to any projects at any time.

4.4 Efficiency Management

on

Improvement

of

Water

Changing the source of energy in deep well system from electrical power to use splitter blade increases the efficiency of the deep well pump with low energy consumption. The flow rate increased in a certain time set with low electrical energy consumed. This will also help reduce the cost spent for electric bills by the owner.

After the decision of installing deep well system, many need to do some proper planning before going to any parties to get installation done. Searching for the lowest rate as possible really helps in reducing cost to spend on the deep well system. As example, find well pump that is suitable for the area of the site needed for water pumping so no wastage happens when the system work efficiently with the area condition.

Putting a signage to the well system could help people to understand what is going on at the current place. Not everyone understands how the deep well system works so it would be much of help to prevent people from confusing about the water flowing from a pipe. There will be no disturbance to the water flowing process and it costs less rather than repairing the stuck well pump.

CONCLUSION Based on the case study that being conducted there are various type of supporting excavation systems but choosing the right excavation systems for suitable soil properties is very important, it also to ensure the support system is not collapse and endanger the surroundings such as workers life, construction materials, and the machineries. Choosing the correct excavation construction support is also essential not only regarding safety but from cost perspective and project progress which is faster or slow. With good excavation support systems choosing good dewatering method also is important because of the soil type might not be suitable for certain method and might destruct the soil and delay the work project, not only that it the dewatering method that supposed to take out the water from the place can't do it function. Choosing dewatering method also is important so it not clash with the support excavation system and disturb each other functional

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