Techniques For Controlling Groundwater And Ground Stability During Excavation

Dewatering Methods

Question:

Discuss about the Installation techniques of pile foundation.

Controlling groundwater and ensuring ground stability during excavation are very important. These are several temporary techniques that can be used to control groundwater and ground stability during excavation. The following are some of this techniques:

This is one of the major methods used for controlling groundwater temporarily. There are several dewatering methods used in construction industry. The two main methods are: exclusion method and pumping method.

Exclusion method: this method involves installing an impermeable structure (known as cut-off wall) to prevent groundwater from the excavation. The cut-off wall stops flow of groundwater to the excavation. Cut-off walls can be created using various geotechnical methods including: slurry trenches and walls, steel sheet piles, compressed air, freeze walls, secant pile walls, diaphragm walls, grout curtains, etc. If properly installed, cut-off walls eliminate or reduce the need for pumping groundwater (Groundwater Engineering, 2014). Some of the methods used to construct or install cut-off walls are: underground excavation and caissons. Underground excavation is used when it is not desirable or possible to lower the level of groundwater or where the soil is extremely pervious. Caisson is where a caisson structure is constructed and during excavation, the structure is sunk by imposed loads or self-weight. Instead of installing a cut-off wall, the excavation can also be protected against groundwater by diverting the water.

Pumping method: this method entails pumping groundwater from several sumps or wells so as to lower groundwater levels temporarily and allow excavation works to be undertaken under stable and dry conditions. Figure 1 below is a schematic diagram of a groundwater pumping system.

There are 5 common pumping techniques used for groundwater dewatering: sump pumping system, well point system, deep well system, ejector or eductor system and siphon draining system. Sump pumping system is where groundwater is allowed to flow into the excavation and collected in sumps from where the water is pumped out (WJ Groundwater, 2017). Well point system is where rings or lines of closely well points (shallow wells) are set up around the excavation and connected to a header pipe. Well point pumps are then used to pump water from these shallow wells on the principle of suction. Deep well system is where electric submersible pumps are used to pump groundwater from a bored well. The wells are bored round the excavation perimeter. Ejector well system is most suitable regulating pore water pressures found in materials that are less permeable. The system’s operation is based on venturi principle. Here, a vacuum is created as high pressure water circulates in the ejector wells. This vacuum facilitates drainage in strata with low permeability. Siphon draining is where water is pumped from installed wells by gravity through siphon pipes. The wells have to be installed above the excavation’s unstable zone so that the pumping can be enabled by gravity (Moving Water Industries Corp., 2016).  

This is the method where groundwater is converted into a solid and impermeable wall of ice. The groundwater is frozen by placing vertical freeze pipes in the soil then removing heat energy through these pipes, as shown in Figure 2 below (Nemati, 2007). When earth temperature reaches 0 °C, groundwater present in the soil turns to ice. The ice continues to solidify with further cooling. Common ground freezing techniques include brine circulation and liquid nitrogen process.

Ground Freezing Techniques

This is a method that ensures ground stability protection of excavation against groundwater effects. The technique simply involves installing or constructing protective support systems around the excavation. Common excavation support and protective systems used are: soil nailing systems, soldier beam & lagging systems, excavation bracing and tieback systems, among others (Kamran, 2007).

Piling is one of the most common and effective methods used to strengthen and support foundations. Piles are used to provide the required support to various engineering structures, including bridges, buildings, dams, industrial structures, etc. (Groundforce, 2017).

Piles can be classified based on the following:

Composition or type of material – piles under this category include: concrete piles, timber piles, steel piles and composite piles (AboutCivil, 2014).

Installation method – piles under this category include: bored piles, driven piles and driven & cast in-site piles.

Function – this is where piles are classified based on their use. They include: end bearing piles, tension piles, friction piles, anchor piles, compaction piles and dolphins and fender piles (Khan, (n.d.)).

Pile installation in Hong Kong can be done using several techniques. The technique used is selected depending on: soil conditions, equipment available, load bearing requirements, local practice, etc. (Adejumo, 2013) Some of these techniques include:

Piles can be driven into the ground using the following methods:

Dropping weight: this is where a hammer (known as drop hammer) with roughly equal weight with that of the pile is lifted in a guide to an appropriate height then released to strike the head of the pile, as shown in Figure 3 below. There two common types of drop hammers used are: compressed-air or single-acting steam and double-acting hammers (The Constructor, 2017).

Vibration: this involves driving piles into the ground using vibratory hammers. The hammers can be powered hydraulically or electrically.

Explosion: this techniques uses explosion charges installed in the ground to create cavities in the ground by crush stones or other soil materials (Yan & Chu, 2005).

Jacking: this is the method where a static driving force is imposed on the pile using a jack. The pile is jacked into the ground using force from a pump and applied through the hydraulic jack, as shown in Figure 4 below.

Jetting: in this method, a water jet is used to soften the ground thus easing penetration of the pile into the ground as shown in Figure 5 below. When a jet of water is directed at one point, it causes fragmentation of the subgrade soils thus decreasing interlocking force and friction between adjacent soil particles. As a result of this, the soil’s bearing capacity beneath the pile tip becomes very low allowing the pile to descend easily (Kimos, 2009).

These methods include:

Continuous flight auger (CFA): in this method, a flight auger fixed with a protective cap at its tip is driven or rotated into the ground using a rotary hydraulic motor connected to it and installed on the earth surface. When the desired depth is attained, workable concreted is impelled via the auger’s hollow stem as shown in Figure 6 below.

Excavation Support and Protective Systems

Figure 6: CFA (Builder's Engineer, 2013)

Underreaming: this technique is used for widening the bottom of a bored pile or for creating tension piles as shown in Figure 7 below.

Figure 7: Diagram showing underreaming (Franki Foundations, (n.d.))

Cement – this technique involves mixing cement with soil to increase the soil’s stability (Kowalski & Starry, 2007).

Lime – the method involves adding lime to the soil resulting to a reduction in plasticity index and increase in soil strength.

Bitumen – it involves adding bitumen to a soil thus improving its cohesion and decreasing water absorption capacity. 

Chemical – this is where soil is mixed with chemicals so as to improve its properties.

Electrical stabilization – this is done using a technique called electro-osmosis.

Grouting – it involves injecting stabilizers into the soil. Categories of grouting techniques include: clay grouting, polymer grouting, chemical grouting, bituminous grouting and chrome lignin grouting.

Geotextiles – this is where geotextiles are embedded into the soil thus improving its stability.

Deep mixing – this is a non-destructive method where a small sized probe is used to improve loose or weak soil strata’s bearing capacity.

In general, ground stabilization methods can be categorized as: mechanical, chemical and alternatives/polymers.

One of the most common and effective methods used in construction of complex foundations is top-down construction method. This method is commonly used where deep excavation is required (Wong & Goh, 2009). This method is very effective in controlling ground movements and displacements of retaining walls (Cotton & Luark, 2010).

Top-down construction method involves massive earthwork. This requires proper design, planning and arrangement of excavation, loading, hauling and depositing activities (Li, et al., 2014). The general procedure of top-down construction method is as follows:

Construct retaining wall – the retaining wall is constructed so as to secure the site where the complex foundation is to be constructed. This prevents external disturbances such as groundwater and also prevents the construction activities on the site from affecting adjacent structures. The retaining wall is permanent and is also referred to as diaphragm wall.

Drill piles or shafts – this is done using the selected method (depending on the type of piles) to the bearing layer. Concrete is poured into these shafts to the lowest point so as to create foundation piers.

Install structural steel columns – these columns are installed into the shafts to extent from ground floor level to foundation pier.

Excavate first basement – excavation is done within the secured area until reaching the first ground floor level. In the process, spoil materials are hauled outside the excavation. In most cases, excavation is done until reaching the final basement level.

Cast first basement floor slab (ground floor) – the first basement floor slab is cast in place using reinforced concrete. The casting process is the same as the one used in casting a typical reinforced concrete floor slab. Diaphragm walls anchor this floor slab. After casting, the slab is allowed to cure. This floor also acts as the diaphragm walls’ lateral bracing. The floor should have access openings for removal of soil and supply of manpower, equipment and building materials. After casting the ground floor slab, construction of the superstructure can now start (Langdon Seah, 2014). 

Pile Installation Techniques

Cast next lower basement floor slab – the casting process is done the same way as the previous one. This new basement slab also provides lateral bracing to the diaphragm walls’ bracing.

Repeat casting process – more basement floor slabs are cast using the same procedure until attaining the desired number.

Cast basement – after finishing to cast all the basement floor slabs, the final basement is cast. This entails constructing a raft level at the bottom. After that, the steel columns are encased using reinforced concreted and formwork so as to become permanent structures. Figure 8 below shows schematic diagram of the final structure

Figure 8: Schematic diagram of top-down construction method (Techmestructures.wordpress.com, 2015)

There are several other techniques that facilitate top-down construction method. These techniques include: ground stabilization, dewatering, cut-off walling, excavation, removal of spoil materials, supply of lateral soil, construction of the basement, etc. Therefore it is important for the company to plan on how each of these activities shall be done.

In top-down construction method, basement slabs are used as lateral bracing systems for the wall system perimeter. The ground and first basement slabs are then constructed, leaving access holes to facilitate excavation below. Once the next subgrade level is done, the floors are used as lateral bracing systems for the wall system perimeter. The general steps of top-down method are as shown in the illustrations below

Advantages of top-down method include: saves time by allowing overlapping of construction activities, enables construction to proceed downwards and upwards simultaneously, the diaphragm is used to support the earth, it enables easier roof construction, it can reduce cost since it eliminates construction of a separate concrete walls for bracing, etc. Drawbacks of this method include: it is difficult to install waterproofing walls on the tunnel walls’ external surface, roof, base slabs and floor connections are more complicated, the wall-slab joints are likely to leak, exterior walls are likely to exceed recommended tolerances, access to excavation can only be through the roof’s shafts or portals, and there is limited space to excavate and construct the bottom slab.

Underground utilities, drainage works and culverts can be constructed using trench or trenchless methods.

These are the conventional methods of constructing underground utilities, culverts and drainage works. The methods typically involves digging trenches, laying pipes or ducts in the trenches and filling the trenches with spoil materials. Here, the top surface of earth is dug out to form a depression. It is in this depression that the pipe or duct is installed then it is backfilled or covered with the excavated soil (spoil) to level the ground. These methods are commonly known as cut and cover methods.

There are various methods of trenching depending on the size of the project and type of soil. For small projects in soft or compressive soils, trenches can be dug manually using hand tools. Trenching can also be done using electrically or hydraulically powered machines or earthmoving equipment. Some of these include: excavator, trencher, bulldozer, backhoe loader, scraper, etc. Construction using trenching methods can either be bottom-up or top-down. Bottom-up construction is where excavation of the trench is done, with the ground providing the support, then the tunnel, pipe or duct is installed. After that, the trench is backfilled to reinstate the surface. Top-down construction starts with building capping beams and side support walls.  A shallow tunnel is then excavated and a roof constructed over it followed by reinstating the surface but leaving access spaces. After that, further excavation and construction takes place below the tunnel roof. 

Classification of Piles

These methods are characterized by minimal surface disturbance and excavation. Some of the trenchless construction methods include the following:

Moling: this is a process where a pneumatically-driven device is forced through the ground until reaching the desired length. In this method, a bore is created using displacement, as shown in Figure 9 below. After that, the duct or pipe is installed. The method is suitable for compressible soils.

Figure 9: Schematic diagram of moling process (Groundforce, 2017)

Tunneling: this is where a tunnel boring machine (TBM) or “mole” is used to excavate circular tunnels. Once the tunnels are excavated, the pipes or ducts are laid into them. This method is applicable to all types of soils and rocks.

Microtunneling (MTM): this method uses a jacking system to push the microtunneling tunnel boring machine (MTBM) into the ground. Operation of the MTBM is done from a control system positioned on the ground. As the machine drills the bore, the excavated soil is removed and the pipe is simultaneously installed. In some cases, continuous pressure can be provided so as to balance earth pressure and groundwater pressure.

Horizontal directional drilling (HDD): in this method, a drilling equipment mounted on the earth’s surface is used to drill a pilot bore filled with a fluid. A larger drilling head is then used to enlarge the bore to the desired size of the product pipe or duct to be installed. This method is suitable for large scale crossing like rivers.

Pipe ramming (PR): in this method, a percussion hammer is mounted on the pipe end. The force from this hammer enables installation of steel casing from launch to reception shaft. The excavation is supported by a casing that is pushed forward through the shaft.

Pipe jacking (PJ): this is the method where pipes are installed directly by pushing them hydraulically through the ground from launch shaft. The method requires someone to be inside the pipe or tunnel so that he/she can do the soil excavation or spoil removal activities (Rafie, 2017). Nevertheless, excavation process can be done mechanically or manually.

Horizontal auger boring (HAB): in this method, a rotating cutting head is used to form a bore extending between a launch and reception pit. The device contains rotating auger flights that remove excavated soil and deposits it to the drive shaft. The method’s steering capacity is limited but it is more economical for straight and short drives than other methods.

Auger boring: this is a method where guided auger devices are used to make borings from launch pit to reception pit. Jacking of pilot pipes is done at controlled slope and direction (German Water Partnership, 2011). After drilling, the borings can be expanded using wider augers. After borings have been made, product pipes or ducts are jacked in.

In general, construction methods for culverts, underground utilities and drainage works can be categorized as: trenching, tunneling and shafts (Safe Work Australia, 2012).

Construction of structures is usually done by constructing the substructure first followed by erecting the superstructure. These structures can be constructed using different methods. Each method has its advantages and disadvantages based on quality, cost, delivery time, efficiency, etc. (Ferrada, et al., 2013).

Pile Installation Techniques

Construction methods can be categorized based on materials used (wood construction, steel construction, concrete construction, composite construction, etc.) and building techniques applied. The discussion in this paper involves construction methods based on techniques or procedures used to construct the building or other structures.

Construction methods can also be classified into two main areas: substructure, superstructure units and lightweight cladding structures.

Most substructures are constructed using the conventional methods. The common methods entail excavating the site, stabilizing the ground, pouring of concrete to make foundation, compacting the concrete and allowing it time to settle. However, some components of the substructure can also be manufactured off-site and transported to the site for installation.

Superstructure units comprise of: platform/stick framing, modular construction, panelized, pods, hybrid and timber framed method.

This is the traditional method of construction where the structure skeleton is assembled step by step on site. In this method, the foundation is constructed first followed by the frame of first-story walls, second floor platform (slab), frame of second-story walls, third floor platform, frame of third-story walls, and so on until lastly the roof framing is installed (Wardell, (n.d.)). After completing the framing, mechanicals that include pipes, ducts and wires are installed through decks or floors and walls. Insulation is also fixed then the finishing work is done to complete the construction.

This method involves manufacturing of flat panel components in the factory and transporting them to site where they are assembled and installed. These components usually comprise of external walls or frames of the structure (load-bearing and non-load-bearing supports). Once the components are installed, other elements of the superstructure can be constructed and integrated on site to complete the structure.

This is construction method combining both modular construction and panelized construction techniques. It is also referred to as semi-volumetric construction method.

These are 3D units produced in the factory and integrated into the structure on site. For buildings, pods may encompass ready-made rooms that are delivered on site and fixed into the building’s framework. The rooms come with pre-installed electrical and plumbing services.

This is where the framework of the structure is made of timber. The timber can be combined with steelwork to make the structure more stable, long lasting and fireproof. 

These comprise of external finishes with low structural loading. They include: timber cladding, brick slips, render systems, rain screen and external insulated finish systems (EIFS) (Zurich Insurance, 2014).

Most of the modern construction methods play a key role in increasing efficiency and sustainability in building and construction sector.

Falsework and formworks play a key role in construction of reinforced concrete structures. By definition, formwork is a temporary structure (although it can also be part or whole permanent) that is used for holding poured concrete so as to mould it into desired dimensions (shape and size) and provide it with necessary support to a point where it can support itself. In other words, formwork acts as a mould for the reinforced concrete structure. Falsework refers to a temporary structure used for supporting a permanent structure when it is being erected until when it can support itself. Falsework usually transfers force from the formwork bearers and sheeting.

The main use of formwork and falsework is to mould reinforced concrete structural components. Fresh concrete is poured into the formwork and falsework then gets moulded to the specified dimensions in the drawings. Therefore it is important to ensure that formworks are precisely constructed.

For formwork to perform its function effectively, it must meet several load requirements. First, the formwork must protect concrete against vibrations and too low or too high temperatures. Second, formwork must not allow fresh concrete to flow out of it. Third, the formwork should be able to safely resist dead loads of reinforcement, fresh concrete and other temporary loads. Fourth, the formwork should maintain permissible dimensional tolerances of the structural component being moulded. Fifth, the formwork should produce concrete structure finish of desired quality. Sixth, the formwork should allow easy placement of required reinforcement. Last but not least, stripping of formwork should be easy and not affect strength or stability of the moulded concrete structure.

Types of formwork

Formworks can be made using steel, aluminium, wood, prefabricated panels or forms, plastic, etc. The formworks should be constructed accurately and using good quality materials. Some of the various types of formwork are:

Foundation formwork: these are formworks used in construction of foundations. The formworks vary depending on the type of foundation. They are usually made of sheeting panels containing formwork bearers, walers and bracing systems.

Wall formwork: these are formworks used in construction of walls. They usually comprise of vertical formwork bearers nailed with sheeting boards on the concrete side. Boards are used to brace the formwork bearers.

Ceiling formwork: these are formworks used in installation of ceilings. They may be made of prefabricated sheeting panels or sheeting boards.

Beam formwork: they are used for construction of beams. They contain prefabricated formwork sheeting at the bottom and sheeting panels on the sides. Cover straps are used to enable nailing of sheeting boards onto the side and bottom panels.

Column formwork: they are used for construction of columns and are similar to beam formwork. Their sheeting panels are fixed in foot rims that are anchored into the ground using steel bolts.

Main components of formworks are: formwork sheeting, formwork bearers and formwork ties. Formwork sheeting are the panels that are directly in contact with the poured concrete. Formwork bearers are the elements that support formwork sheeting directly. These elements transfer forces from the formwork to other supporting members, formwork ties and the soil through falsework. Formwork ties are elements that are fixed across the formwork sheeting to absorb pressure.

Formworks and falsework influence various properties of reinforced concrete structures including strength, durability, stability, appearance, etc. This emphasizes the need to ensure accurate and proper design, construction, installation, use and stripping of formworks and falsework. These process must be performed by qualified personnel and supervised by the engineer. After using these temporary structures, they get removed. The process of removing them is called stripping. Most of the stripped formworks get reused.

There are numerous hazards in construction industry. Below are some of the potential hazards in civil engineering activities:

Falls – some construction activities require working at a height, which restricts access and mobility of workers. One common cause of falls is collapse of scaffolds. Because of the challenges associated with working at a height, a worker can easily fall leading to injuries or even death. In addition to that, materials can also fall from above and injuries those workers below (Healthy Working Lives, 2016).

Moving objects/equipment – machines, materials and other objects are constantly moving on construction sites. This movement poses risks as people on site can be accidentally hit by the moving objects.

Slips and trips – construction sites contain a variety of items that can easily cause slips and trips or even falls. Workers walking on site can unintentionally hit these items or even fall in holes.

Cave-ins – this hazard is caused by several factors including failure or collapse of shoring system or absence of sloping in excavations (Center for Construction Research and Training, 2017). They are also known as caught-in-hazards and the most common type is trench collapse.

Electricity – it can cause injuries or even death. Electric shock and electrocution are common hazards on construction sites. The most affected persons are electrical workers who may come in contact with current from electrical and wiring components such as appliances, tools, and overhead and underground power lines (Orji & Nwachukwu, 2016).

Noise – a typical construction site is characterized by loud and repetitive noise that can cause hearing problems (Lovell, 2014). The noise is usually caused by machines, tools and equipment. If workers are exposed to noise for a long time, they can lose their hearing capacity.

Fire – use of flammable materials create fire hazards on construction sites. The fire may also be caused by other activities such as welding, burning, etc. Flammable materials or processes likely to ignite fire should be used and done carefully. Fire extinguishers should also be provided for use in case of fire.

Confined space – entering and working in a confined space is a major construction hazard. Confined spaces do not have adequate oxygen and workers cannot escape in case of any dangers. It is important to test confined spaces before allowing workers to enter them and the workers n confined spaces must be monitored at all time (Chappell, (n.d.)).

Inappropriate personal protective equipment (PPE) – lack of proper PPE exposes construction workers to numerous physical and chemical risks. Incorrect use of the right PPE also has the same effects. Therefore all workers must always be in the right PPE when on site.

Unqualified workers – this is a major hazard because unqualified workers perform tasks incorrectly and without considering their health and safety risks. Unqualified workers do not recognize the need for compliance with design and construction specifications and therefore their actions pose health and safety risks to themselves and others. 

Health hazards – construction workers are exposed to a wide range of health hazards. These hazards are usually caused by exposure to hazardous substances, inhalation of toxic fumes, vibration, excess heat, etc. Examples of diseases resulting from health hazards include: silicosis, asthma, cancer, etc.

Equipment – many construction workers get injured by machines and other equipment every day. These injuries can be caused by incompetency of the machine operators, defects of the machines, carelessness of workers or accidental actions. Construction equipment can also hit workers causing serious injuries (Sa, 2011). In some cases, the equipment may cause death. So it is important to inspect equipment regularly and ensure that they are operated by qualified persons.    

Biological hazards – these are hazards resulting from exposure to toxic organic substances or infectious microbes. For example, excavation workers can be affected by a lung infection called histoplasmosis, which is caused by soil fungus (Weeks, 2011).

Generally, construction hazards can be classified as: physical hazards, chemical hazards, biological hazards and social hazards (Construction Safety Council, 2012).

Management of health, safety and welfare of workers and the general public is very important in construction industry. Construction companies are required to comply with specific legal framework requirements in the area where the project is being implemented.

Health and Safety at Work Act (HSWA) was adopted by the Great Britain parliament in 1974. The Act was used across all sectors including construction industry. The main aim of this Act was to provide main regulations and duties to various stakeholders involved in construction projects. Since then, various regulations have been formulated to improve safety and health in construction sector. One of the new regulations is CDM 2007. The regulation was adopted in April 2007. Its main aim is to reduce ill health and construction accidents in Great Britain through improvement of planning and management strategies adopted by stakeholders in the construction industry.

CDM 2007 are regulations defining legal duties aimed at ensuring safe construction operations in the UK. These regulations assign specific duties on various stakeholders involved in construction projects. The regulations were formulated by the construction division of the Health Safety Executive (HSE). The main objectives of CDM 2007 are: improve planning and management of construction projects; assign duties to appropriate personnel for purposes of managing on-site risks; and administer health and safety on site.

The following are the general duties of different duty holders under CDM 2007:

Clients

Duties of clients include: appoint other duty holders; provide adequate resources and time; prepare and provide relevant information to other duty holders (Health and Safety Executive, 2015); ensure that welfare facilities are provided; ensure that principal contractor and designer perform their duties accordingly; and facilitate efficient coordination and cooperation between client representatives and other stakeholders.

CDM coordinator

The main roles of a CDM coordinator are: advise the client on health and safety matters and risk management issues; notify HSE about notifiable projects; and help the client with their duties. CDM coordinators are required in notifiable projects only.

Designers

Their duties include: ensuring that clients are aware of their duties before start of design work; ensuring that competent persons are involved in the design process; preparing and modifying project designs; eliminating or mitigating health and safety risks throughout the project lifecycle; and providing relevant information to other duty holders to enable them perform their duties

Principal contractor

Legal duties of principal coordinators are: ensure that adequate resources are provided and allocated to various stakeholders; develop and oversee implementation of construction plan; manage subcontractors; facilitate consultation of employees on health and safety issues; provide safety and health training to employees; ensure that adequate welfare facilities are provided to workforce; ensure that subcontractors get relevant information and documents on time; etc.

Contractors 

Their duties include: ensure safety of their workers; ensure that they work with competent subcontractors; ensure that their workers have adequate information; ensure that they work in coordination with other stakeholders; and provide sufficient welfare facilities to workforce.

Workers

Their duties include: perform tasks in areas of their competence; report hazards and risks to contractors; work in coordination with others to ensure their safety and health and that of others; and ensure that they adhere to site safety and health procedures and rules.

Cap 59 outlines safety and health protection that should be provided to persons working in industrial sector, which include factories, container and cargo handling activities, construction sites, repair workshops, catering businesses, etc. The Cap highlights duties of employers and employees in industrial workplaces in relation to safety and health matters. Generally, employers are supposed to take care of their employees’ safety and health while at workplace; and employees are supposed to contribute positively to ensure that they perform their duties in a safe and healthy manner. Other sections of the cap outline the following: details of employees and their tasks; medical records of employees; procedures for reporting accidents at work; strategies of preventing accidents; hygiene; offences & penalties; and dangerous incidents; among others.

The planning supervisor is appointed by the client. He is usually appointed at a very early stage of the project, mostly during planning stage. In order to perform his responsibilities adequately, the planning supervisor should have sufficient knowledge and expertise in communication, management, planning and construction. The planning supervisor is also known as principal designer or construction, design and management (CDM (coordinator). Some of the roles of planning supervisor in an engineering project include:

Enhance cooperation of designers – he ensures that all designers involved in the project work as a team so as to avoid and reduce risks. The planning supervisor acts as the middleman for facilitating coordination of designers and resolve any issues that may arise.

Facilitate effective communication between the client, contractors and designers – a project can only be completed successfully if there is effective communication between major stakeholders. The planning supervisor enhances communication between designers, contractors and the client especially during pre-construction stage. He ensures that there is effective flow of information between these stakeholders. 

Advising the client on his responsibilities – the planning supervisor advises and reminds the client about his responsibilities and what he should do to facilitate successful implementation of the project. This includes the information and resources that the client should provide and when to provide them.

Advising the client on competence of contractors and designers – the planning supervisor assesses the qualifications of contractors and designers then advises the client on whether they are competent and able to perform the activities of the project (Health and Safety Executive, 2015).  

Ensuring compliance of designers – the planning supervisor ensures that designers fulfil their duties especially in connection with how they have evaluated health & safety risks and the steps taken to eliminate or mitigate them. In addition, the planning advisor checks various design aspects and how they may affect safety & health during construction and post-construction phases.  

Advising the client on health & safety issues – it is the planning supervisor who advises the client on how health and safety issues should be handled on site. He ensures that various issues related to health & safety are considered and integrated in the design by working with designers to avoid or reduce/control predictable health & safety risks. As a result of this, the planning supervisor makes significant contributions towards preparation of health & safety plan.

Preparation of health & safety file and health & safety plans – health & safety plan and file are very important documents in any civil engineering project. The planning supervisor ensures that these documents are professionally and properly prepared so that all activities are done in a safe manner.

Informing the health & safety executive – the planning supervisor advises the health & safety executive (HSE) on various issues aimed at enhancing safety on site during the construction phase (MDA Services, 2015). The HSE ensures that the issues raised are analyzed and considered in the design process.

Reviewing design changes – the planning supervisor reviews any changes made to the design especially during the construction phase. He ensures that all stakeholders involved in the project are informed about these changes and agree to implement them in accordance with the contract terms.

Notifying the principal contractor about foreseeable risks – the planning supervisor informs the principal contractor about possible risks that may be encountered during construction phase and identifies strategies of controlling or reducing them (Darley PCM, 2015).

Civil engineers are responsible for developing solutions to numerous engineering problems. These problems include technical, environmental, economic and social problems. Some of the solutions to these problems include the following:

Modern technologies have helped civil engineers to develop a wide range of solutions to various problems. These technologies make it possible to simulate different solutions so as to select the best option. As a result of this, engineers are able to investigate the performance or effects of each solution before developing it fully. Some of these technologies include: lean construction and building information modeling (BIM). These technologies have numerous benefits including: quick project delivery, improved quality, reduced costs, environmental conservation, etc.

This concept aims at conserving natural resources by minimizing the amount of resources used by a structure throughout its lifecycle. For instance, it reduces the amount of water, energy and other building materials used to construct houses. Civil engineers use this as a solution to the global problem of climate change and depletion of resources. The solution improves people’s quality of life both directly and indirectly.

This is a solution used to ensure that structures are designed, constructed and used appropriately. Use of accurate design and construction processes helps in creating structures that meet all engineering standards and codes. Each stage of these processes also undergoes quality checks, which improves quality of final products.

Many lives are lost in construction industry every year due to health and safety related issues. As a result of this, engineers now emphasize on the need to ensure implementation of appropriate health and safety procedures in all projects. Besides that, engineers ensure that structures built have appropriate safety facilities during operation phase. 

This is a major solution that has the potential of making the world a better place now and in the future. Engineers are now promoting use of renewable energy such as solar energy, wind energy, geothermal energy, biomass and hydroelectric energy. This energy is available for free, is unlimited and have zero or very low emissions. All parts of the world can generate at least one form of renewable energy, hence this solution is capable of ensuring supply of clean energy to every person on earth. The solution has also increased water and air quality.

Engineers have developed this solution to solve the problem of natural resource depletion. As global population continues to increase, natural resources are constantly depleting. This is a big problem because people may lack resources in the future. Having identified this as a looming problem, engineers have developed methods of recycling materials and reusing them in construction projects. The materials are recycled using proper methods that do not compromise their quality. Besides conserving natural resources, recycling is also helping to keep the world clean thus improving air and water quality.

Construction industry is one of the sectors that generate a lot of resources. Civil engineers have developed various techniques of reducing wastes generated at different stages of project implementation. Common techniques include lean construction, BIM, prefabrication, etc. 

Civil engineers have developed a wide range of alternative materials and methods of productions. These materials and methods have various benefits including: increase production, improve strength and quality of products, reduce production time, improve air and water quality, increase life quality, etc. Examples of these solutions are: development of drought-resistant seeds that have increased food production in arid and semi-arid areas; use of modern, water efficient irrigation methods to increase agricultural production in deserts; and use of alternative building materials to reduce house prices.     

Safety is a very critical element in any civil engineering project. It is mandatory for the company to prepare a construction safety plan so as to ensure that all activities are performed in a safe environment. The plan should be prepared before commencement of work. 

Project manager: the project manager performs the following responsibilities: reviews site conditions; obtains necessary site access permissions; ensures that safety plans are implemented appropriately; informs other project team members about their roles; coordinates with other project team members to ensure successful implementation of safety plans; and coordinates with relevant public officials to ensure that safety requirements are accomplished (Langan Engineering & Environmental Services, Inc., 2012).

Health and safety coordinator (HSC): HSC works with SSO to prepare and update safety plans; coordinates with SSO to perform jobsite safety inspections; ensures that workers are properly trained on safety matters; maintains personnel records of training, certifications, medical tests, etc.; and prepares root cause analysis reports and preventive action strategies for various incidents.

Site safety officer (SSO): SSO implements safety procedures; oversees field operations; keeps records of site activities and incidents; coordinates with public officials to ensure safety adherence; ensures that necessary safety equipment are provided on site and are in functional condition; recurrently inspects PPE; ensures that all entry and exit signs are properly installed; monitors workers to identify any signs of stress and fatigue; makes follow-up on implementation of safety plans; coordinates provision of medical care during emergencies; reports emergency cases; maintains emergency communication lines; coordinates disposal of materials; ensures provision of necessary equipment; and helps in preparing root cause analysis reports.

Client: the client is required to provide the necessary resources that facilitate implementation of safety plans.

Designer: the designer ensures that the project is designed by considering and integrating all necessary safety parameters.

Contractor: it is the contractor who implements the safety plan. So contractors ensures that all activities on site are performed by following the developed safety procedures.

A safety plan should identify all potential hazards in the project and their associated risks, analyze them and establish suitable prevention or mitigation measures.

All workers on site should be in appropriate PPE. This helps in protecting them against various hazards.

To minimize safety risks, only qualified personnel should be allowed to perform specific duties. Competent personnel are able to use the equipment properly and identify any defects before they cause problems.

Every job on site should be done using the right equipment. The equipment should be properly maintained and stored.

The company should provide her employees with on-going safety training so that they can understand safety procedures and tips (DePace, 2010).

Some of the materials used on construction sites are hazardous thus it is important for every material to be properly labelled, stored and used.

During an emergency, the following procedure should be adopted:

On-site communication: specific methods of communication to be used in case of an emergency should be determined at every site.

Emergency telephone numbers: it is important to post emergency telephone numbers of site emergency response team, medical response team, firefighters and police.

Job site address: this address should be posted near communication station to make it easier for those reporting an emergency to provide the location of the incident.

First aid responders: the company should have trained and qualified first aid team designated to respond to emergencies.

Emergency crew principal – a specific person should be designated to give emergency crews directions on how to reach the site quickly and easily during an emergency.

Exits – all workers should know where emergency exits are located. Signs and symbols showing these exits should be erected or posted in open and visible places. The exits should be easily accessible, properly illuminated and sizeable.

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