Contract Management for Land Reclamation Projects
Contract Management for Land Reclamation Projects
The execution of a reclamation project is very complex and has a high element of risk and uncertainty requiring experience, sophisticated techniques, and expensive equipment. A comprehensive reclamation contract is, therefore, necessary to provide an enforceable agreement between the client and the contractor to enable them to successfully execute the work. It should be a legal agreement that addresses all contingencies covering the scope of work, payment, quality of work, and schedule of work.
The form and type of contract will affect the final price of a project, as much as some of the engineering specifications because of the element of risk inherent in the reclamation operations. Time allowed for the tender, the mobilization period, the timing of the award, and the duration of the contract have to be taken into consideration. In addition, variable weather and soil conditions affect the works and these uncertainties should either be minimized prior to the tender, or the risks should be shared between the client and the contractor. The contract should as far as possible reflect the type of work to be executed and the circumstances in which it is being performed.
Reclamation and ground improvement projects are often major projects which require technical expertise, good and appropriate equipment, as well as effective human resource and financial management. Only contractors with strong financial support and experience in managing mega-projects should be considered for such big projects. Contractors who own reclamation equipment such as dredgers, barges, and transportation trucks have an added advantage. Traditionally, Dutch and Belgian dredging companies have been known to be the most suitable contractors for such work. There are also a few large Japanese contractors who own dredging equipment. They may also be suitable to execute such reclamation projects. South Korean companies are also becoming increasingly involved in dredging and reclamation projects.
The most suitable type of contract is one that splits the risk appropriately between the client and the contractor. There are basically two types of contracts: the fixed price contract and the cost reimbursement contract (cost-plus contract). Until recently, an open competitive tender system was traditionally favored by national governments for awarding reclamation contracts. However, a modified form is now more popular in which the reclamation contractors are first required to submit prequalification documents, and only prequalified contractors will be invited to tender. This reduces the risk of awarding contracts to irresponsible contractors who put in bids which are far below the cost of the project and who then have difficulty in completing the project successfully.
In order to successfully implement land reclamation and ground improvement projects, suitably written conditions are necessary for the contract. The conditions of contract that have traditionally been adopted in the United Kingdom (UK) and its former colonies are those of the ICE General Conditions of Contract drawn up by the Institution of Civil Engineers, UK, for overseas works, mainly in civil engineering construction. The first edition, published in August 1956, was reprinted in November 1969. Part II of the document, on “Condition of Particular Application”, is usually modified to suit a particular area, country, or type of project. The laws and procedures that have to be complied with in a particular country are generally described in this section. The most internationally accepted conditions of contract are those of the FIDIC Conditions of Contract, 3rd edition, March 1977, published by FIDIC (Fédération Internationale des Ingénieurs – Conseils).
Both material and fuel costs greatly affect the overall expenditure of the reclamation project. Therefore, special conditions such as claims for marine fuel and fluctuations in the price of imported materials have to be provided for by a special clause.
In the course of the reclamation, there could be excessive inclement weather conditions which would affect the progress of the project. Thus, the contract should provide for claims of extension of time due to unexpected weather conditions, based on the number of days in each calendar month when weather may be considered to be inclement. This clause is usually included in Part II of the Conditions of Contract.
Two types of specifications are usually used in civil engineering projects: method specification, and performance specification. Both types of specifications may be applied to reclamation projects. However, sometimes a combination of both types of specifications is adopted. Method specification may discourage innovation by the contractor. Therefore, in some cases only a general method is specified and the contractor is allowed to propose an alternative method to achieve the desired results. The work is then controlled by performance monitoring, or checks.
Since reclamation projects usually cover a large area, the work is often sub-divided into several sub-areas and implemented in stages. The stages should be planned to take into account the available working area, sequence of future usage, ease of scheduling navigation, and drainage. Not only is it necessary to specify the stages in terms of area but also the stages in terms of fill levels and work scope. For shallow reclamation, the level of fill to be carried out is generally specified, which is usually one meter above the high tide level with one lift. Other works, such as shore protection structures, are usually carried out at this stage. If reclamation is carried out over a deep seabed, two or more lifts may be required. If the ground condition permits, it is usually specified that the first lift is to be done by direct dumping and the second lift onwards by hydraulic filling. In very soft ground conditions, an initial thin sand blanket may be required. These stages have to be clearly described in the specifications.
Before starting the filling, dredging works are usually carried out to remove unsuitable material or to form sandkeys for the shore protection works. Although the method of dredging is rarely specified, cutter suction dredging is usually not allowed for this work. Only grab or bucket dredgers are suitable for this type of dredging. The dredged level is specified based on site investigation data, and the gradient of slope is also specified so as to control the stability of the dredged slope.
The fill material needs to be specified in order to control the quality of the land fill, which is generally expected to provide good load-bearing capacity for construction equipment and also for future development. The quality of fill material is specified either by grain size distribution envelopes, or fine content. Generally, the use of fine material of less than 63 microns is limited to less than 20%. Unsuitable material, such as organic shell, coral, plants, roots and clay should not be included in the fill material. It is also necessary to check the chemical composition of the fill material and any contaminated soil should be rejected. The source of fill material is either
specified by the client or left to the contractors to source from their own borrow area.
Although the method of filling is usually not specified, the formation of mudwaves and slips, which alter the characteristic of the seabed and lead to unacceptable additional settlements, must be controlled through the specifications. It should also be specified that the cost of any loss in fill volume due to settlement occurring during stage filling should be borne by the contractor. The contractor has also to allow for any losses during transportation and from settlements in the unit rate of fill material.
For PVD installation, the spacing and depth of PVDs to be installed are usually specified for each area. However, the exhibited design specification is again usually controlled by the performance specification, which will be discussed later. In addition to the specification of PVD, a pilot embankment must be carried out at the initial stage of the reclamation. The purpose of a pilot test is usually to determine the type of drain, the suitable spacing, and the appropriate installation depth. Several types of PVDs are usually installed with different spacings and sometimes, varying penetration depths. Generally, sufficient separation must be provided between the various plots to eliminate boundary affects. An area with no PVDs is also used as a control area. The performance of each PVD is monitored with geotechnical instrumentation and assessed with in-situ and laboratory testing. Some pilot tests need to be carried out not only to determine the type of PVDs and the spacing to be provided, but also to ascertain the suitability of the proposed installation rig, mandrel, and anchors.
Only after the installation of the PVDs can the minimum period of surcharge be specified. However, this again is controlled by the performance specification. The method of placement of the surcharge is specified in order to achieve the required density of the fill. This could be supplemented with a performance specification.
In order to obtain the best performing PVD system, detailed specifications of the PVD including a quality control system are essential. The details of these specifications have been given in Chapter 7, and the quality control process is explained in detail in Chapter 13.
The method of removal is not usually specified. However, the level to be achieved is generally given. The last stage of the work is deep compaction. The method of compaction must be specified with an exhibited design describing the total applied energy and energy per square meter. However, an alternative proposal is usually accepted if the proposed method is equal or better than the exhibited design. Again, final acceptance is controlled by
the performance specification. Trial compaction using the exhibited method and the alternative methods proposed by the contractor have to be carried out in order to select the most suitable method, energy, equipment, spacing, and number of passes. Trial compaction is usually carried out on various test plots with different types of equipment and amounts of energy.
The typical design of shore protection structures is usually described in the contract as well as the material to be used, such as rock or geotextiles. Details of rock and geotextile specifications are given in Chapter 8. The method of construction is usually not specified.
16.2.1 Local authority requirements
The requirements of the local authorities, such as the environmental, marine, land and port authorities, are also included in the specifications. For example, the environmental agency would usually require contractors to protect the environment from pollution and to control the environmental impact as a result of the creation of the land. For example, silt barricades are required to prevent the drifting of silt outside the working area. Marine and port authorities usually require the contractor to monitor wave, current, tide, and water quality. In order to control the changes to the seabed caused by dredging and the deposition of fill, the port authority usually demands the monitoring of the seabed and the beach. The type and quantity of dredged material must also be checked before it can be dumped at an approved dumping ground. The dumped soils are usually capped with clean sand.
Site investigation, such as boring and in-situ testing, need to be carried out and this must be specified as well as the method of testing. Several types of site investigation are necessary to select the suitable borrow material and to characterize the seabed soil and fill material after deposition and densification. Details of site investigation have been given in an earlier chapter.
16.2.2 Performance specification
Specifications for measuring the performance of ground improvement with PVD must be carefully written. Generally, the completion of ground improvement is measured by the degree of consolidation. Traditionally, only 90% of the degree of consolidation can be specified because of the much longer time required to complete the remaining 10%. Therefore, the consequences of the occurrence of settlement after construction have to be anticipated. Alternatively, the land can be overloaded with the equivalent of this shortfall of 10% of the degree of consolidation. However, the degree
of consolidation alone is not sufficient to define the required ground improvement. It has to be related to the required loading, applied loading, or remaining loading after the settlement. Three examples of specifications written by the authors for some projects in the Far East are given below.
The consolidation settlement of the soft compressible soil to be achieved shall be an improvement of soil such that 90% of the primary consolidation settlement under the specified surcharge load intensity and the reclaimed fill has taken place in the soft compressible soil before the removal of the surcharge.
The consolidation settlement of the soft compressible soil to be achieved shall be an improvement of soil such that 90% of the primary consolidation settlement under the load of reclaimed fill up to the finished level has taken place in the soft compressible soil before the removal of the surcharge.
The consolidation settlement of the soft compressible soil to be achieved shall be an improvement of soil such that 90% of the primary consolidation settlement under the load of the reclaimed fill up to the specified finished level and the future load of 20 KPa, has taken place in the soft compressible soil before the removal of the surcharge. Allowance must be made for the change in stress resulting from the change in groundwater level up to +3 mCD during or after consolidation settlement.
Again, there are two significant ways of measuring the degree of consolidation. One is the degree of consolidation in terms of settlement and the other is the degree of consolidation in terms of effective stress gain. A technically well-planned and implemented ground improvement project can achieve the degree of consolidation both in terms of settlement and effective stress gain. Although the effective stress gain lags behind the settlement, these two converge to almost 100% of improvement. Therefore, at the time when 90% consolidation is achieved, these two measurements are close although effective stress gain is slightly lower.
However, the designer can choose the type of specifications required depending upon future usage. The purpose of ground improvement is simply to eliminate future settlement, and to ascertain whether the degree of consolidation specified in terms of settlement is sufficient. After achieving
the required degree of settlement, there will usually be residual excess pore pressure but this will be dissipated with minimum settlement because of the non-linearity of the effective stress gain behavior. Three examples are given below of specifications relating to the degree of consolidation in terms of effective stress.
220.127.116.11— Effective stress gain
The degree of consolidation to be achieved shall be 90% of the primary consolidation resulting from both the increase in stress because of the recently reclaimed land and the load intensity of sand surcharge from +4mCD to the levels specified in the drawings. Allowance must also be made for the change in stress resulting from the settlement of the reclaimed land and the surcharge caused by the consolidation settlement of the soft clay. The specified degree of consolidation shall be achieved at all levels within the entire thickness of the very soft to soft soil, including the reclaimed fill. This degree of consolidation shall be achieved within the respective times specified for handing over each area of treatment.
The degree of consolidation to be achieved shall be 90% of the primary consolidation resulting from the increase in stress caused by the recently reclaimed land up to the specified finish level. Allowance of surcharge must be made for the settlement of the reclaimed land resulting from the settlement of the soft clay during the consolidation process. The specified degree of consolidation shall be achieved at all levels within the entire thickness of the very soft to soft soil, including the reclaimed fill. This degree of consolidation shall be achieved within the respective times specified for handing over each area of treatment.
The degree of consolidation to be achieved shall be 90% of the primary consolidation resulting from both the increase in stress caused by the recently reclaimed land up to specified finished level and the future load of 20 KPa. Allowance must be made for the change in stress caused by the change in groundwater level to +3 mCD during or after consolidation. The specified degree of consolidation shall be achieved at all levels within the entire thickness of the very soft to soft soil, including the reclaimed fill. This degree of consolidation shall be achieved within the respective times specified for handing over each area of treatment.
However, if ground improvement is carried out to improve the strength of the soil to a certain level, it is deemed necessary that the required degree of consolidation is achieved in terms of effective stress gain. For such projects, another specification is added to ensure that the required strength is obtained. This is generally related to the required load, applied load, or remaining load after settlement. Generally, a strength equivalent to 20-30% of the relevant load is specified, depending upon the type of soil. Three examples of specifications written by the authors for some projects in the Far East are given below.
18.104.22.168— Shear strength
The shear strength to be achieved shall be undrained shear strength increments throughout the entire depth of very soft to soft compressible soil using prefabricated band-shaped plastic drains to achieve a 20% increase in effective vertical stress from the reclamation fill and the specified surcharge load intensity. Allowance must also be made for the change in stress due to settlement of the reclaimed land and surcharge caused by the consolidation settlement of the soft clay.
The shear strength to be achieved shall be undrained shear strength increments throughout the entire depth of very soft to soft compressible soil using prefabricated band-shaped plastic drains, to achieve a 20% increase in effective vertical stress from the reclamation fill up to the finished level. Allowance of surcharge must be made for the settlement of the reclaimed land due to the settlement of the soft clay during the consolidation process.
The shear strength to be achieved shall be undrained shear strength increments throughout the entire depth of very soft to soft compressible soil using prefabricated band-shaped plastic drains to achieve a 20% increase in effective vertical stress from the reclamation fill up to the finished level and a future load of 20 KPa intensity. Allowance must also be nade for the change in stress as a result of the change in groundwater level up to +3 mCD during or after consolidation.
An example of performance specifications for the differential settlement is shown on the following page.
Additionally, the contractor must ensure that the differential settlement is not more than 50mm within a distance of 100 meters along the length and breadth of the treated area over a period of one year commencing from the completion of the soil improvement works.
The densification of granular soil is generally measured by relative density. Since relative density is not easy to measure, the improvement is usually measured by using cone resistance. A static cone is usually used to measure post-improvement density. If a certain reduction of elastic settlement is to be achieved from the granular fill, the required modulus of granular fill is specified and usually measured with a pressuremeter.
The method of measurement of work done is generally specified in the specifications. For the payment of fill material, the fill volume is usually measured by pre- and post-filling surveys. With this method, the settlement which occurs during filling is already taken into account. However, in some projects, payment is made based on the transported volume, which is measured on board. The payment for the fill material is generally based on the rate per cubic meter. For PVD, the payment is based on the installed drain length which is measured manually or with an automatic recorder. In some projects, the payment is made based on the area of improvement at a fixed rate per square meter, regardless of the installation depth.
Densification works are also measured by the improved area and paid at a per square meter rate. Shore protection works, especially for rock bunds and rip-raps, are measured by pre- and post-filling surveys and payment is made by volume at a rate per cubic meter. The geotexile laid for separation is measured and paid at a rate per square meter.
For site investigation, the works are paid by a fixed rate per meter run, or per borehole. Sometimes, instead of specifying the number of boreholes and tests, the provision of equipment and manpower to carry out site investigation for the duration of the project is specified. Payment is made for the equipment and manpower, including capital and running costs.
The use of geotechnical instruments is also specified at a cost per instrument with, and without, running costs. If the running cost is not included, payment for monitoring is calculated at a cost per trip.
Laboratory tests are usually paid at a cost per test. For mega projects involving ground improvement works, it is worth considering setting up a laboratory. Payments are then made for setting up the laboratory and the running cost.
Strong project management teams are essential for the implementation of huge reclamation and ground improvement projects. The project manager must not only have contract management skills but must also be able to appreciate the need for specialists such as geotechnical engineers and coastal engineers. An understanding of dredging techniques and equipment is also necessary. Three major areas should be represented in the project team: contract management, geotechnical expertise, and coastal engineering. The contract management team will be responsible for planning, scheduling, procurement, and quantity surveying with discussion and advice from the other two divisions. While all the necessary geotechnical investigations and testing should be undertaken by the geotechnical division, the coastal and marine environmental measurements should be carried out under the direction of coastal engineers.
The success of a project, in which high risks and unknown conditions are likely to occur, requires a give-and-take philosophy by both contractors and consultants. Insisting on following specifications to the letter must be discouraged whist upholding standards and maintaining fairness to both contractor and client. This approach must be adopted not only at the management level, but should permeate through all levels of the execution, especially the men on the site itself. This spirit of understanding and cooperation between both parties involved is often the common factor in all successfully completed projects where technical and safety standards are high and claims resulting from unforeseen conditions and circumstances are minimal.