Analisis Pengaruh Grouting terhadap Rembesan Air Laut pada Lokasi Galian Pipa Pesat PLTU Sudimoro, Kabupaten Pacitan, Jawa Timur

Abstract

Along with increasing of requirement of electrics, addition of power station building is considerably required to fulfill electric power supply demands. One of power station building project which is under construction is PLTU Sudimoro, located in district of Sudimoro, Pacitan region, East Java. During construction of PLTU in Sudimoro, it was planned to make dig for placement of penstock, it is a high pressured pipe which have function to channel and direct water to turbine chimney. However, condition in the field expressed that dig situated under sea-water, therefore, if soil layer in the represented area is such of high permeability, sea water will seep and the penstock will be drained. The most effective method to prevent this is by grouting method. The purpose of this research is to know well the influence of grouting related to sea-water seepage seen by change of lugeon unit value, coefficient permeability, and seepage rate before and after grouting, and also its effectiveness after grouting. Methodologies have to do is descriptively and analysis. Descriptive method is done with literature study through other reference sources and books like internet, research reports and journals as reference to know regional geology for research area, and compiling of theories. Analytical method is performed in form of analysis base of lugeon unit value, permeability coefficient, seepage rate before and after grouting, and also effectiveness of grouting. From result the calculation, then it is compared the value before and after grouting to know the influence of grouting related to sea-water seepage. The data used is permeability test results, seepage rate data, and core drill log data. After grouting, lugeon unit value (LU) is showing a smaller number than before grouting is performed, it is less than 3 (LU<3) which means that execution of grouting can lessen ability of soil to conduct water at lugeon unit less than 3 (LU<3). The coefficient permeability value after grouting is showing a smaller number than before grouting, which means soil condition to be impermeable progressively. Seepage rate value after grouting is showing a smaller than before grouting, which means sea water seepage decreases after grouting. Effectiveness of grouting in average is 66,37%, this indicate that influence of grouting to soil layer is in good condition. Influence of grouting related to sea-water seepage is can increase of soil impermeability.