Selection borrow area

The feasibility of a project strongly depends on the availability of sufficient suitable fill material in the vicinity of the reclamation site. Chapter 5 Selection borrow area, describes the most important criteria for the selection of a borrow area. 

When assessing the soil characteristics in a potential borrow area, the important aspect will be the suitabihty of the soil as fill material. It should be kept in mind that the dredging operations might alter the in situ properties of the soil (e.g. when dredging with a trailer suction hopper dredger, most of the silt/clay fraction will be washed out). This matter is discussed in more detail in Chapter 5, Selection borrow area. 

Selection borrow area define borrow area as material source borrow area should be physically accessible for the equipment waterdepth (min., max.) ... 

Selection borrow area quality of fill material ... 

Selection borrow area—quality fill material (see Chapter 5)... 

It is also important to determine the in-situ characteristics of the materials within the borrow area as they have a significant impact on the dredging method, selection of the most suitable type of equipment and the planning. 

Results of the data collection must also include information on in-situ density and shear strength in order to enable an accurate selection of the type of dredging equipment to be employed within the borrow area. 

Although the final choice with respect to the execution method also involves other aspects such as project planning, economics, hydrographic conditions, availability of plant, distance between borrow and reclamation area, local regulations and legislation, reliable geotechnical information on the proposed borrow area and fill material is crucial for a Contractor to select the most appropriate dredging tools. 

The main purpose of a borrow area is to provide suitable fill material. Generally the required properties of the material can be split up per area or depth below the siuface. High quality fill materials (as may be required for the top layers of a land reclamation) are often referred to as selected fill . Bulk material is referred to as general fill . 

All of the parameters on the right hand side of Equation (a) are fixed values except for jc, the variable to be optimized. Assume the cost of installed insulation per unit area can be represented by the relation C0 + Cxx, where C0 and Cx are constants (C0 = fixed installation cost and Cx = incremental cost per foot of thickness). The insulation has a lifetime of 5 years and must be replaced at that time. The funds to purchase and install the insulation can be borrowed from a bank and paid back in five annual installments. Let r be the fraction of the installed cost to be paid each year to the bank. The value of r selected depends on the interest rate of the funds borrowed and will be explained in Section 3.2. 

This approach is based on a concept borrowed from the membrane-based separations area - ultrathin film composite membranes. Ultrathin film composite membranes consist of an ultrathin (less than ca. 100 nm-thick) polymer dcin coated onto the surface of a microporous support membrane. These composite membranes have made a tremendous impact on the field of membrane-bas separations because they can offer high permeate flux without sacrificing chemical selectivity. These two qualities (high permeate flux and high chemical selectivity) are also required in polymeric barrier layers in chemical sensors. Therefore, the ultrathin film composite membrane concept ould be applicable to sensor design. In this paper we present proof of this concept by riiowing the response characteristics of a prototype glucose sensor based on an ultrathin frlm composite membrane. 

Rather than adding another facet to this already breathtaking panorama of the field, it might be appropriate here to emphasize "where it is going". The present essay will therefore not be extensively documented but rather present some conjectures for the future, mainly based on and illustrated by work performed in the author s laboratories. An outlook towards the perspectives of supramolecular chemistry, and more generally of supramolecular science, has been presented a few years ago [7]. These perspectives still hold and will be borrowed in part from this earlier text. Considerations on some selected areas will be given along three main themes ... 

Knowledge of the presence of sensitive clays at or near borrow and/or reclamation areas in the planning phase of a project is clearly of great importance. The selection of these areas depends on the risks imposed by these sensitive clays and the cost for precautionary or remedial measures. Since the precise combination of factors that determine the sensitivity of clay is still unknown, occurrence of sudden strength loss is difficult to predict. Therefore, laboratory tests are necessary when the presence of sensitive clays is likely. These tests include the determination of the strain rate dependent strength behaviour (Leroueil et al, 1985), mineralogical and chemical content, the moisture content and the particle size distribution. 

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