| Abstrakt: |
The design, construction and management of engineering projects tend to be large scale, indivisible, and long-term facilities, with investments taking place in waves. This investment process due to constant further development has become a critical issue in the world management of civil engineering with regard to sectors of the national and private economy. These kinds of investments cannot be limited to solving just the mechanical problem. They should be designed with consideration of their life cycle, all costs of the project and construction stage, as well as what will be obtained during the lifetime of the investment. Due to the increasing environmental contamination, especially soil and ground-water, the need of restoration of these degraded lands for construction investment has emerged. Nowadays, the remediation technologies are more often focused on using passive engineering constructions installed in the ground, for example permeable reactive barriers (PRB) which allow for land use during decontamination processes. As with any investment, information about the costs of remediation technologies is as significant in determining their final commercial success as are efficiencies in the data. Technology investors need to have consistent cost information to conclude whether the technology will be economical or not. In the case of PRB technologies, the installation is a major investment cost, where one of the biggest drivers are material costs. The most important parameters for PRB cost and design are dimensions (thickness, length and height should be enough to treat the entire width of contaminants and to prevent their migration). The most important challenge is to determine the optimal thickness of a PRB, which provides the residence time appropriate for reducing the concentration of contaminants. In an engineering investment which involves designing, systems and decision making, optimization is crucial in creating best design subjects irrespective of constraints. In this paper two-objective optimization methods for multi-layered PRB design are considered. The proposed methods are characterized by following special features: elimination of a timeconsuming simulation model; application of a universal, simple Excel spreadsheet-based optimisation model that calculates minimum cost of PRB using solver; and the usage of real input variability based on literature and laboratory tests. In view of minimizing cost of reactive materials and maximizing the resident time of contamination, the required thicknesses of PRB layers: activated carbon, zeolite and zero valent iron were calculated. |
