ABSTRACT
The largest Sewage Treatment Plant in Malaysia was recently completed in 2008, which caters to an ultimate capacity of 1.2 million population equivalent. The project successfully improved Georgetown’s (in Penang) sewage disposal system and rehabilitated an unsanitary site. The subsoils at the site are primarily soft marine clay deposits up to 10 m deep. One third of the site was covered by a former garbage dump site. The original proposed foundation was conventional piled foundation but this was later found to present a few undesirable construction limitations such as noise pollution during pile driving; and transportation and storage of pre-cast piles on a congested site. Alternative ground improvement technology comprising of Vibro Concrete Columns, Cement Columns and Vibro Stone Columns were introduced to support the process tanks and ancillary structures. The construction methods are considered environmental friendly as they produced minimum spoil and consumed relatively low energy. This paper describes the design and construction of the alternative ground improvement methods including quality control measures and insitu tests. Hydrotest and settlement monitoring results, proving tank performance, are also presented.
Keywords: Ground improvement; vibro stone columns; vibro concrete columns; cement columns; sewage treatment plant.
