My Attachment at Ammico Contracting Company in Doha, Qatar - Report Example

BEB701 Work Integrated Learning 1 –For Engineers. Report 2: Workplace Activities and Reflections Employer: Ammico Contracting Co. W.L.L. Doha-Qatar. Ammico, summer vacation 2011-2013. Work Placement Day in this report: 30 days. Executive Summary This is a reflective report on the activities and observations that occurred during the last 30 days of my attachment at Ammico Contracting Company in Doha, Qatar. The last 30 days of my attachment program were spent learning the technical details of civil engineering, as I was now fully attached to the working division of the company. This part of the attachment period proved to be more insightful than the initial period of the attachment because I was now fully used to the operations of the company. Since I was now fully conversant with the health and safety guidelines of the company, I could participate in many activities, which contributed greatly to my learning of civil engineering operations and procedures. I obtained hands-on experience in borehole drilling and backfilling, piling, anchor installation, grouting, anchor locking and distressing, demolition of secant walls, dewatering and installation of piezometers. I learnt a lot during this period under several instructors and supervisors, each with their own brand of ethics but all aimed at ensuring optimal working conditions for the workers of the company. I therefore had the chance to observe civil engineering operations from the different perspectives of the professionals working for this international company. Contents Executive Summary i Contents ii List of Figures ii 1.0 Introduction 1 2.0 Workplace Background 1 3.0 Work Activities 3 3.1 Reflective field entry 1 3 3.2 Reflective field entry 2 5 3.3 Reflective field entry 3 8 3.4 Reflective field entry 4 12 3.5 Reflective field entry 5 13 4.0 Conclusion 16 5.0 References 17 Appendix A: Work Log 19 Appendix B: Certificates/s of Time Worked - CTW 21 Appendix C: Reflective Notes 22 Appendix D: Work Place Health and Safety Checklist 38 List of Figures Figure 1-The post grouting effect 6 Figure 2-Section of exhumed post grouted anchor 7 Figure 3-Dimensionsions after post grouting 7 Figure 4-Proposed layout plan of shoring system for exaction depth-13.70 QND 10 Figure 5-screen image of a civil 3D design 11 Figure 6-Drilling for anchors 29 Figure 7- Shows a survey and Demarcation for pile locations 29 Figure 8- Ammico-owned road cleaner 34 Figure 9- Demolition of primary concrete piles 35 Figure 10- dewatering exercise 37 Figure 11-dewatering stages 37 1.0 Introduction The second part of my attachment period was more eventful than the first part because I was more involved in the duties and responsibilities of the different sections. These included the construction sections, the procurement section, the logistics section and the safety section. The people with whom I worked as well as the supervisors in charge of these operations began to trust me more and hence provided more opportunities for me to get involved in the work assigned to their sections. I was therefore accorded more freedom with the machinery and equipment, which enabled me to learn more about the work protocols of Ammico Contracting Company. 2.0 Workplace Background My last 30 days at Ammico Contracting Company were spent in the field, where I benefitted from direct participation in company projects and assignments. The duties and responsibilities assigned to me during this period were meant to hone my skills in the civil engineering field and provide me with hands-on experience. Drilling and backfilling of boreholes took up the first few days of the second part of this attachment. As a qualified member of the safety department, I was to make sure all safety measures pertaining to the work to be accomplished were met. I was involved in making sure that the vehicles were utilised in the correct order, as required by the supervising officer. I was also in charge of making sure that the work site was free from materials that could cause slippage, tripping or falling of the workers. Due to the fact that I was pursuing civil engineering and was considered a quick learner, I was sometimes tasked with training the workers in safety features and precautions prior to commencement of work. The health, safety and environmental officer and the site supervisor also tasked me with ensuring that the area of operation was clear of debris. During drilling operations, I was also tasked with making sure an area that was smooth and hard was available to hold the micro drilling rig machine. The preparation of a fire safety plan as well as ensuring the workers utilized the appropriate protective devices such as hard hats, safety shoes and safety glasses was my responsibility (Ammico 2010a). The duties and responsibilities with which I was tasked during the other work procedures were not very different from those I carried out during the drilling and backfilling of boreholes. The technical details changed, but the safety functions remained. During piling, my duties and responsibilities involved positioning of the floating barge and the placement and adjustment of the template used in pile driving. I also helped in the removal of the pile driving templates and the temporary piles used in the operation (Ammico 2010d). Apart from my involvement in the operational side of the work, I was also involved in the design phase of the projects under construction. I was involved in the analysis and evaluation of load behaviour and the reaction of concrete to sustained loads during background anchoring (NCHRP 2009). During grouting, I was tasked with coming up with mechanisms that would prevent the tipping over of the grout pump, as well as making sure conditions were ideal for the flow of concrete. In some instances, I was assigned with ensuring that the movement of equipment and personnel were up to specifications. The experience I gained during this period was vital to my development, as I became familiar with most of Ammico’s civil engineering operations. 3.0 Work Activities 3.1 Reflective field entry 1 Situation Before and during excavation and piling, I was required to help with the procurement of materials and equipment. My work included the recording and documentation of all chosen materials, in their required quantities. The procurement officer met with the engineering officers, forepersons and the section supervisors to determine which materials would be essential to the process and how much of them should be obtained. Once or twice, I chipped in with a suggestion of a material I felt they had overlooked. Task I was tasked with the recording of all the materials chosen during the meeting. Prior to the meeting, I was required to go to each section to collect the suggestions of workers on which materials they felt should be obtained, even though these were not necessarily integral to the work to be accomplished. Such materials or equipment would be useful in ensuring the comfort of the workers. Action I took this task seriously, as I was aware of the fact that the procurement officers depended on me to provide comprehensive and accurate information. I sifted through the information I had obtained from the workers in a bid to eliminate material superfluous to the work to be performed. This was necessary to avoid wasting time for the procurement team. During the meeting, I wrote down every bit of information discussed and then compiled the list for the procurement officer. I was also responsible for taking the final list to the typing pool for the production of hardcopies of the list for filing in addition to the soft copies. The company took its record keeping very seriously and performed the task with an efficiency that required complete concentration and dedication. Result I finished the task in record time. I was very efficient and the procurement officer remarked on it. The procurement officer pointed out that past attaches had wasted time asking irrelevant questions during the meeting but was very impressed with how I seemed to adapt very quickly. They were also very impressed with my suggestions for extra equipment and tools that needed to be procured. They claimed it would have been more costly to order the materials separately but that I prevented all that. I was therefore quite pleased with how I did this task, which indicated my growth as a civil engineer. Learnt I quickly learnt the importance of efficiency while carrying out any operation in the company. I also perceived that the section heads and forepersons were very concerned with the safety of their workers. They insisted on getting the best personal protection gear for their workers and did not compromise when it came to safety issues. I also learnt that during such meetings a formal attitude was necessary even during a heated conversation. The respect for each person’s position in the company was acknowledged during the meeting, with junior members addressing their seniors with the necessary formality. This task also enabled me to learn about minute writing and record keeping, which were considered very important elements for the smooth running of the company. My supervisor informed me that record keeping ensured the future of the company as the company could only chart their future path based on their past history. 3.2 Reflective field entry 2 Situation While grouting, my team encountered a problem when we hit a patch of soft earth. We were therefore required to redesign the ground anchors based on the ground capacity instead of the normal strand capacity. We therefore carried out post grouting to make sure the work was up to standards. Task We were required to look for an alternative to the normal grouting technique. I participated in the designing of anchors by utilizing a post grouting technique, which allowed the improvement of soil properties hence boosting the capacity of the anchorage system. After drilling and grouting the borehole, anchor strands were inserted in conjunction with a post grouting pipe together with manchetes, i.e. grouting with ‘tube à manchette’ (TAM). Action Normally, the formula Tf = π × D ×L × α × Cu is used in grouting, where Tf is the working load, D is the borehole, L is the fixed anchor length, α is the adhesion factor and Cu is the mean undrained shear strength over a fixed length. The adhesion factor is taken as 0.4. Using the normal grouting technique in solid soils, less than half of the clay’s undrained shear stress is used in tension. After post grouting, an adhesion factor of between 1.4 and 3 was applied. This enabled us to enhance the working capacity of anchors up to three (3) times a normal grouted anchor. The images below show the effect of post grouting using the formula described above (Fig. 1), plus a section of an exhumed post grouted anchor (Fig. 2). Fig 3 shows the change in dimensions that occurred after the application of an increased adhesion factor (Veloso 2009). Figure 1-The post grouting effect Figure 2-Section of exhumed post grouted anchor Figure 3-Dimensionsions after post grouting Result The results for the average bond stress increased for the post grouted anchors with a conventional mean bond stress mobility increasing from 150kN/m2 to 450 kN/m2. The grouting unit was therefore able to install anchors in poor and non-ideal ground conditions. This was also a huge advantage because it was possible to reduce the amount of anchors on some projects by using higher loads. Higher loads enabled us to use more spacing between anchors. It also enabled us to reduce the overall anchor lengths in some instances when there were space restrictions. I was also able to observe how different people deal with challenges and the techniques they use to do so. Learnt I learnt a lot about the design and installation of ground anchors during this period. It was also enlightening as to the challenges that civil engineers face in day-to-day operations. I was able to see how different people deal with challenges and the techniques they used, including asking for advice from senior personnel and searching for answers from libraries and online sources. I learnt the different methods of grouting and post grouting and their modified formulas in soft soils. 3.3 Reflective field entry 3 Situation The excavation of phases 2 and 3 as well as the demolition of part of a secant wall encountered during the excavation operation included excavations to allow for the construction of underground utilities such as vehicle access and car parking accommodations. The reason is that the concrete levels of the shoring system were lower than the actual ground level in most of the sections, the centre of attention was on the site border. This was so that a working platform could be established for the installation of a shoring system. Task I was tasked with helping in the making of working drawings and the sequence plans for the excavation. I was also involved in writing the site report detailing the tests carried out on the site before the start of work, as well as carrying out markings for excavation to be done adjacent to the earth retaining wall, leaving a sufficient corridor along the perimeter of the site in that region. We carried out marking in white paint to show the required width and length that was to be left along the earthen retaining wall. Appendix C further describes the survey and demarcation exercise. Fig. 4 shows the proposed shoring system for the project and is a combination of the diaphragm wall and the secant wall. Action We carried out the tasks in teams and came up with the required drawings and sequence plans for the excavations, which we handed over for the owner’s and engineer’s information evaluation and review. AutoCAD® Civil 3D® software were utilized because of the magnitude and complexity of the design. This software is Building Information Modeling (BIM) software from Autodesk used in civil engineering analysis, design modelling and simulation. We then carried out the marking exercise under the supervision of the safety supervisor to the required specifications (Autodesk 2013; Ammico 2010b) Figure 4-Proposed layout plan of shoring system for exaction depth-13.70 QND Result The use of AutoCAD Civil 3D® enabled us to work quickly, efficiently and accurately in the design of the drawings and sequence plans. The program eliminated small errors that could have had eventual major negative effects on the project. It allowed us to simulate the finished project accurately using the provided dimensions to make changes where necessary. The sequence plans were clear and easy to understand and visualize, hence simplifying operations for the machinery operators. Fig. 5 is a screen image of a complex roundabout that was to be developed in the Doha area. Figure 5-screen image of a civil 3D design Learnt The use of AutoCAD Civil 3D® taught me that technology has a part to play in the achievement of efficiency in civil engineering. It proved that computer analysis allows one to access a large number of design options during civil engineering. I also learnt that 3D modelling and testing was essential in the generation of accurate prototypes that could be used to produce better end products during operations. I also learnt the importance of cooperation in teamwork during design operations. It enabled me to learn from the other members of the design team, as they possessed expertise in both civil engineering practices and computer design and modelling analysis (Gill 2010). 3.4 Reflective field entry 4 Situation Before the drilling of boreholes and installation of anchors, we were required to clear the site for the drilling of the borehole as well as the installation of billboards to notify people of the construction process underway in the area. Clearing of debris would insure safety for both the operators and the machinery to be used in the process. The clearing exercise is described further in Appendix C – Reflective Field Notes. Task The sites for the billboards were chosen according to their access to the general population. The areas selected were accessed by large numbers of people, and the billboards were designed to be visible to both people in vehicles and those on foot. We cleared the site for the boreholes both manually and using machinery. Boulders and debris were the main hindrances, and we tried our best to get rid of them to the extent possible, to provide the best working conditions. In addition, we were tasked with setting up billboards to notify the public of the operations that were being undertaken in the region. Action After clearance of the obstructions and obtaining the permit, we started the construction of the billboard. We followed the procedures provided by the section supervisor set for the billboards by choosing the correct drilling depth for the billboard posts as well as deciding on the angle the sign would face in relation to the traffic. After pouring the concrete, we affixed the permit to the billboard to show the validity of the sign before leaving (Rolfe 2008). Result The clearance exercise for both the borehole drilling and the construction of billboards was tiresome as well as cumbersome. However, it was carried out to the best possible degree due to the significance of the operation to the safety of the workers. We worked hard and completed the allocated tasks within the set time limit provided by the supervisor. The setting up of the billboard also presented a few challenges. Even though we had permits for the erection of the billboards, some landowners and neighbors were not in support of the billboards. However, we convinced these stakeholders of the importance of the signs and promised them that as soon as the projects was completed, we would pull them down. Learnt I learnt a lot about the technical details of drilling. I learnt the different range of tests that needed to be carried out on the soil before commencement of drilling. My interaction with property owners and tenants taught me a lot about the importance of obtaining permission before carrying out any exercise on externally owned property. 3.5 Reflective field entry 5 Situation In the last week of my attachment, we carried out extensive excavation and dewatering works in the heart of Doha, in phases 2 and 3. I was assigned to a team that was in charge risk management before the excavation and dewatering works started. The risk management exercise encompassed the development of a risk assessment report and its solutions. Tasks We were tasked with identifying all the risks and hazards that could put the exercise in jeopardy by causing equipment failure and/or cause injury to the workers. We therefore had to study excavation and dewatering works extensively and intensively and come up with a risk assessment report that would be used for risk management. Action We started our task by first identifying all the hazards that would be encountered during the two exercises including vibrations, chemical gases, collapse due to the nature of strata, fractures and faults, exposure of the excavation to wet weather and the presence of loads close to the edge of the excavation edge. We also identified the risks associated with excavation failure and their consequences. After identification, we assessed the risks associated with these hazards and the control measures that could be put into place to counter them. The final action included a comprehensive review of our report before turning it over for implementation. A sample of the risk assessment is provided below (Comcare 2011). Table 1-risk assessment Activity Hazard Risk controls 1 Access and use of tools and equipment Injury to operators and bystanders medium Safety precautions to be strictly adhered while using tools and equipment. Tools and equipment should only be accessed by authorized personnel Maintenance crew to make sure the machinery are in proper working condition 2 Excavation activity Vibrations Collapse of walls Fractures Consistent use of personal protective equipment like helmets, safety shoes, ear muffs, goggles for eye protection and gloves First aid kits and boxes to be at hand with a trained person in charge of it The work supervisor should be given the mandate to stop the work in case of an accident Result The report was graciously accepted by the engineer in charge of the exercise, and its recommendations were followed to the letter. The health, environment and safety engineer congratulated us for a job well done. Learnt I learnt that every civil engineering operation is only successful if a lot of effort first goes into the preparation stage of each exercise. The preparation should involve a comprehensive risk assessment and a detailed risk management plan to counter the consequences posed by the hazards. I also learnt the importance of well-directed motivation for the workers. This is because the rest of my team members worked especially hard when they were praised by our supervisor. 4.0 Conclusion If the first days of the attachment were an introduction to the civil engineering field, the last 30 days of my attachment instilled in me knowledge and experience of most of the civil engineering practices. I gained firsthand experience in essential civil and construction exercises including drilling of boreholes, backfilling, piling, background anchor installation, grouting of anchors, anchor distressing, excavation, demolitions, billboard construction, dewatering, installation of piezometers and the preparation of risk assessment reports. The second part of the attachment period was different from the first period because I was now used to the company and the personnel had enough confidence in me to let me undertake some of the work on my own. Even though I was directed in most of my assigned tasks, I was given ample space to show my knowledge, skill and expertise. My confidence increased exponentially during this period, and I trusted myself to take on assignments that I would have otherwise considered above my level. The attachment was therefore the best experience a civil engineer can have. 5.0 References Ammico 2010a, Heart of Doha development project phase 2 & 3 – enabling works: job safety analysis, Doc. Ref. ACC/HOD/JSA/AID REV 00, Ammico Contracting Co. W.L.L., Doha. Ammico 2010b, Method statement for installation of diaphragm wall, Doc. Ref. ACC/HOD/CMS/DW Rev 00, Ammico Contracting Co. W.L.L., Doha. Ammico 2010c, Preliminary method statement for enabling works package, Doc. Ref. ACC/HOD/PMS Rev 00, Ammico Contracting Co. W.L.L., Doha. Ammico 2010d, Preliminary method statement for marine piling works for KNPC sulphur handling facilities project, Doc. Ref. ACC/HHI/PMS REV 00, Ammico Contracting Co. W.L.L., Doha. Autodesk, 2013, Building information modeling, viewed 5th May 2013, Comcare 2011, Excavation, viewed 7th may 2013, Con-Tech 2011, Strand anchor systems for permanent and temporary rock and soil anchors, retrieved from Gill, KS 2010, Impact of information technology in the field of civil engineering, viewed 12th May 2013, HIROSE 2012, Construction work, viewed 5th May 2013, ILO 1995, Safety, health and welfare on construction sites: A training manual, International Labour Office, London. NCHRP 2009, Adhesive anchors in concrete under sustained loading conditions, retrieved from OSHA 2002, Excavations, viewed 6th May 2013, Rolfe, F 2008, How to build a billboard the correct way: Billboards and outdoor advertising, viewed 6th may 2013, Veloso, GA 2009, How to Enhance Ground Anchors Capacity in Soft Soils, retrieved from Zapata-Medina, DG 2007, Semi empirical method for designing excavation support systems based on deformation control, retrieved from Appendix A: Work Log Appendix B: Certificates/s of Time Worked - CTW Appendix C: Reflective Notes Situation Apart from procuring of materials and equipment during the excavation, there was also a need to practically involve and understand how the activity is done. I was required to work hand in hand with engineering officers so as to learn more about excavation. Severally, I greatly assisted the engineering officers on what need to be done so as to effectively and efficiently complete the task. Task I was tasked with assessing the entire area that needs excavation. Before then I was supposed to meet with quantity surveyors to get a clue on the nature of the surface to be excavated. Meeting with quantity surveyors was very essential as I was required, in my assessment, quantify the cost of excavation. I was also required to assess the safety of the activity to other workers. Action I undertook the assigned task very seriously, as I knew the entire project and safety of the people at workplace really depend on me. I convinced the survey team to give me accurate data relating to the cost of excavation. I also effectively inquired about the soil type and its effects to the surrounding population, in case of excavation. I systematically compiled my data and forward it to the forepersons. Result The excavation exercise was indeed successful although a number of challenges arose. Some of the challenges that arose include the existence of design errors, minor accidents also took place, striking utilities that were unknown and construction errors. Although challenges existed in the process we managed to complete the task within the stipulated deadline. Lesson Learnt I learnt that team work is essential when it comes to handling tasks such as excavation. Most of the tasks performed were as a result of effective coordination between the excavation team. I also learnt that undertaking excavation is an activity that is encompassed by many risks. As a result there is need to ensure that safety measures are maintained at all times. Additional Appendices The heart of Doha project was one of a kind. It was unique because it was a world-class development project that consisted of the construction of blocks of interconnected squares and buildings. The project was aimed at developing and regenerating 35 hectares of land. It was essential to construct a basement extending over the entire area, to be developed for the containment of major utility services, car parking space and service area access. The excavation was to be carried out to a fourth basement level in most cases, which meant excavating to a level of 13.70 meters. In some instances, the excavation went up to the fifth basement level, which would be an excavation up to 17.20 meters, or displacement of an additional 23,392 m3 of soil (Ammico 2010c). During the construction of the Doha convention centre and the Tower project, extensive excavation needed to be done adjacent to the diaphragm wall, in the double basement area and in the triple basement area. Excavation is defined as any construction operation or activity where earth, rock and other materials inside or on the ground are moved or relocated by the use of equipment, tools and/or explosives. The excavation conducted during the construction of the Doha convention centre was carried out in calculated and precise stages. Prior to the commencement of the exercise, we conducted an exercise to determine the risks that workers would face during the exercise. I found out that excavation can be a dangerous exercise with different hazards present during the exercise. Excavation can be a dangerous activity with even the most experienced workers concerned about the consequences of an accident during excavation. Unexpected collapse of walls could cause workers to be buried alive, asphyxiate or suffocate. I learned that even though excavation involves moving soil, rocks or a mixture of soil and rocks, the presence of water during an excavation is nearly always guaranteed. Flooding or the presence of heavy rains during an excavation exercise was one of the hazards that are usually present. Another hazard was found to be cracks that are normally caused by adverse weather conditions; pressure is released as the soil dries during the dry season or under a scorching sun. Another hazard that we discovered during the risk assessment exercise for the excavation exercise was the fact that soils in the region did not have the capability of supporting their own weight, hence the need to develop protective measures during the excavation exercise. The Quality Control Engineer (AQC) and the project manager were involved throughout the risk management phase (ILO 1995). Tests and analyses that we carried out on the soil (during both excavation and drilling operations) revealed that the site of the construction comprised layer deposits of fill materials found to have a thickness of 0.3 meters up to 1.7 meters. Layers of residual soil were encountered below the layer of fill material. The depth of the residual layers ranged from 0.6 meters to 2.5 meters below ground. Below the residual and fill material layers, bedrock material was encountered. This material was varicoloured with strength varying from moderately weak to moderately strong. Subsequently, a layer of Simsima limestone was encountered below this, but that was not the last layer. Midra limestone shale was unearthed between 15.6 meters to 25.8 meters below ground level (bgl). Below these layers, the Fahahil velates ranged between 16.4 meters and 26.7 meters below ground level. A formation of Rus was found in boreholes under the Midra shale at depths that ranged between 16.5 meters and 26.35 meters below the ground and extending to the deepest ends of the boreholes. After conducting the risk assessment exercise, we conducted a clearing and grubbing exercise. Clearing and grubbing of the site included removing all the available perishable materials that existed on the site. These mostly comprised stumps, debris, agricultural materials, tree roots and weeds. Clearing is the removal and disposal of trees and brush, while grubbing refers to the removal and disposal of roots and stumps. We performed the two processes concurrently so as to get the site ready quickly for topsoil stripping (Comcare 2008). For the safety of personnel, equipment and general public safety, we installed sufficient and well-secured stop blocks to prevent the accidental driving of vehicles into the excavation. This could happen while reversing, a process known as tipping. We placed the blocks a suitable distance from the edge of the excavation to avoid straining the soil and to prevent soil breakage due to the weight of vehicles. We also worked on the construction of access routes and ladders for personnel and the passage of light-scale equipment. Even though I was not attached to the electrical section at the time of the excavation exercise, I assisted them in setting up lighting areas to provide light to chosen sections. The excavation started after the completion of around 75 meters of the diaphragm wall and after the wall movement monitoring system had been installed. For excavation bordering the wall, equipment used for the top soil included buckets mounted on excavators was utilized. Areas having rock layers were another matter altogether because rock breakers mounted on excavators was used to break or chisel through the rock. The initial excavations extended approximately six to seven meters beneath the ground and further excavation was only commenced after the plastering of each portion. This excavation continued until the ground anchor level was reached. We promptly installed ground anchors while other crews worked on plastering these sections. Excavation resumed after we finished installing ground anchors and plastering was completed. Fig. 6 shows the machinery and procedure used in the drilling for anchors. The equipment consists of a pair of multi jacks that are applied in the stressing of the anchors. Apart from participating in the construction side of the project, I tried to be an all-round civil engineer and also participated in the survey that was concurrent with the excavation project. Even before work on the project, a detailed film and photographic survey was conducted of the existing structures around or near the boundaries of the work. This included all structures within 20 meters of the boundary of the work to be carried out. The surveys were important because they could be used to monitor any damage said to happen to the existing structures during the excavation or other processes that were carried out during the development of the heart of Doha project. We documented the existing heritage structures that were next to the work boundaries by using video and picture capture/presentation. Throughout the survey, we liaised with representatives from Doha Company who provided us with benchmarks and baselines to use as reference points to help us verify the benchmarks that we had already set from the photo and video evidence. Figure 6-Drilling for anchors Figure 7- Shows a survey and Demarcation for pile locations In addition to this, we verified the temporary benchmarks that were shown on previous survey plans that existed for the work site. Those benchmarks that were shown on the survey plans but no longer existed were re-established. We also set out temporary benchmarks by utilizing permanent governmental benchmarks to establish and carry out the work within the boundaries of the site. Before the excavation exercise began in earnest, it was necessary to field check all the pre-existing conditions on the work site. This included the precise location of all underground services available in the construction area. It was essential to pinpoint the exact locations of the underground utilities so that the necessary work could be carried out, including protection, support, removal and/or disposal. We verified all the data we got from our field check with the Doha municipality records in order to avoid discrepancies or/and omissions. We also contacted utility companies who provided us with the exact locations and plans of their utility installations. These included sewer lines, telephone lines, fuel lines, electricity lines and water pipes (OSHA 2002). The major materials that we used during this exercise included concrete for piles and the earth retaining system; a lot of steel that was procured for both the earth retaining system and piles; stranded wires, centralizers and anchorages that were needed for the installation of ground anchors; monitoring systems and hoses that were used during the dewatering process and temporary hoarding around the perimeter of the site. The anchors were necessary for the stabilization of the earth retaining wall and were created by the building of underground concrete piles 14 cm in diameter. Other materials that were already in place (hence I was not involved in their procurement) included dewatering pumps and generators. After the procurement of materials, I helped the QHSE manager’s team carry out a quality assessment of all the ordered materials. Our assessment was aimed at making sure all the delivered materials were in conformity with the set standards and specifications (HIROSE 2012; Con- Tech 2011). The list of equipment that was utilized in the main part of the work is impressive, as the machines were the top-of-the-range models of the highest quality. The machines for the main work functions included diaphragm wall cutters, dewatering pumps, anchoring machines, piling rigs, concrete pumps, diesel generators, dump trucks, service cranes, excavators, rock breakers, concrete pumps and shovels. All this equipment was owned by Ammico Contracting Company. It was at this point that I realized the massive potential and capabilities that the company possessed. I was awed by this experience and when I asked if Ammico Contracting had participated in or undertaken other projects of this scale. I was told about several of these projects, including the Al Quds Tower project with an excavation quantity of 400,000 m3 and the Qatar national bank headquarter tower project with an excavation quantity of 1,172,109 m3. Safety considerations and the necessity to follow set construction procedures made it necessary to establish positive systems of support. Because the depth of excavation was not constant alongside the perimeter, two positive support systems were proposed to allow for the economization of the project. The two positive systems of support were based on two considerations. The first was that the secant pile wall was to be installed where the excavated depth of the wall was not more than 11.5 meters. The second consideration was for a diaphragm wall to be installed where the excavated depth of the wall was more than 11.5 m. I learnt that in deep excavations, concerns of excessive lateral movement are always present. Excessive lateral movement can be the cause of major displacements and rotations in the neighbouring structures. This was another factor in the erection of positive systems of support. Another important factor was the protection of people from suddenly caving ground. In designing an appropriate positive support system, it was noted that the deep shoring system required single and multiple tie-back ground anchor levels to counter the imposed soil pressures and to take the ground water pressure. In the construction of the diaphragm wall and the related ground anchors, we had to consider several factors during their design. This included the ground movement of adjacent buildings. Both horizontal and vertical movements were considered. The movement of adjacent buildings and structures was limited to 12 mm and below, while the horizontal and vertical movement of utilities was limited to 25 mm and below. This was so that damage to buildings, structures and utilities could be minimized. In those areas that were known or indicated to have utilities, provisional tieback ground anchors were located as far away as possible, more than 6 meters away from the utilities (Zapata-Medina 2007). After the verification of boundaries for the work site, site fencing was carried out. We made sure during such installations that properly approved exit and entry points were established. The site engineer of each section was in charge of the supervision and coordination of this task. S&B system hoarding in addition to 2.4 meters of continuous steel hoarding that was high powder-coated and stepped as necessary to follow the ground contours with concrete blocks mounted on the surface were utilized effectively. Kerb meshing coupled with red warning lights spaced at 400 mm were also incorporated into the fence. The project logo held by a powder-coated plate made out of aluminium by the use of silkscreen printing was also installed. We installed a billboard 9.4 meters high. We designed and installed its foundation, lighting and printing image on a recommended flex fabric. Even before the start of this exercise, we had to obtain permission in the form of permits from the municipality. All the materials that we used in the construction of billboards were weather and pollution resistant. Throughout the excavation, earth retention systems, secant wall building, ground anchor installation, dewatering activities and monitoring activities we revisited the hoarding occasionally to repair damaged sections and in some cases to replace them completely. On occasion, I was given the responsibility to supervise their cleaning when they got too dusty and obscured. Work on the Doha project was extensive as well as extremely intensive. It was therefore necessary to construct some temporary facilities useful for the needs of the workers on the various sites. Some of the facilities that we put up included working places for senior personnel, short-term utilities and storage spaces for materials, prayer rooms equipped with appropriate ablution facilities and smoking areas with sufficient fire fighting equipment. When setting up these facilities, we followed plans and guides provided by the site supervisor to ensure they were only constructed at the approved locations. This was a safety as well as a technical factor, as there was a need to avoid having to demolish and reconstruct these temporary facilities as construction progressed. This included the need to build a temporary access road. It was absolutely necessary for everything to be factored into the plan before commencement of work. There was supervision from Ammico senior personnel at the commencement and during the execution of all activities at the work site. This was, as my attachment supervisor explained, to keep in view the necessary pollution prevention techniques during the construction exercise. It was also necessary to enforce the waste management techniques established by the company. The health, safety and environmental officer informed us that the culture of the company also encompassed proper care regarding the preservation and maintenance of a clean surrounding area and environment. Road cleaners owned by the company were provided for the express purpose of providing cleaning services for the pavements and areas surrounding the construction sites (Fig. 8). To uphold the practice of cleanliness and environmental protection, during excavation, the excavated material was transferred to a temporary storage area within the perimeters of the site. Subsequently, the material was loaded onto tipper trucks for disposal in dumping areas designated by the municipality Figure 8- Ammico-owned road cleaner Because excavation was one of the most work-intensive activities, it was required to start immediately as soon as a project was started or when we moved to a new site. Therefore, as soon as the secant wall became exposed, its demolition was immediately initiated. I was attached to the observation team of demolition process and by the end of the exercise; I had internalized and understood the methodology for the process. The first step was the demolition of the primary non reinforced concrete by utilizing an auger mounted on an excavator. It was astonishing to watch the auger accomplish its task without producing vibrations during the demolition. Figure 9- Demolition of primary concrete piles The second step involved demolition of the secondary reinforced concrete piles. This second stage was more complex than the first process because it involved scratching off the concrete from the piles to expose the steel. This was made possible by mounting a scratcher on the excavator. After the steel reinforcement in the secondary piles had been exposed, they were then torched out of the secondary pile. The pile was then pulled out and broken down on the ground into smaller pieces. Excavation introduces a lot of vibrations in the ground. It is therefore necessary to install soil nails, which are used to steady and stabilize excavation slopes after excavation. Unlike ground anchors, which are used to seal the ground, the use of soil nails is a passive precaution. That is because soil nails develop tension only when there is lateral deformation of the ground. They are therefore installed in excavated walls or exposed soils to make sure the adjacent soils are stable. The soil nails are installed progressively into the exposed slope. The procedure involves drilling a hole of 100 mm diameter on the affected slope at a particular designated angle and pumping grout into the hole. The depth of the hole is not random either; it is provided by design calculations. After grouting, a steel bar of designated diameter is introduced into the grouted hole. After this, wire mesh made from steel was installed on the surface that had been excavated before shortcreting could be carried out. When it was determined that the grout had attained sufficient strength, a hexagonal nut was inserted and tightened on the head of the bar. The soil nails were firmly linked to the wall facing using a bearing plate and the aforementioned hexagonal nut. In the Doha region, the water table was expected at a depth of between 1.15 meters and 11.8 meters below ground level, while the arranged excavation was at levels of up to 13.70 meters. It was therefore a foregone conclusion that a significant dewatering system would be needed at the excavation site. The dewatering systems that we employed were designed to lower the excavation area water table below the excavation depth. This was necessary to enable work to be carried out on dry and stable land. The dewatering system was also designed to preserve the stability of the base and walls of the excavated areas and trenches. It was also essential in maintaining the uplift pressure below the overburden pressure. The uplift pressure was caused by the groundwater below the excavation level. The Ammico dewatering system was designed in such a way that it acted independently from other dewatering systems that could have been present in the neighbouring area. Dewatering was carried out in two phases. The first phase was accomplished while excavation was being carried out while the second phase was after excavation had been completed. Figures 10 and 11 show the dewatering exercise and the stages undertaken during the dewatering exercise Figure 10- dewatering exercise Figure 11-dewatering stages Appendix D: Work Place Health and Safety Checklist Read More