Ketut Buda Artana, A.A. BGS. Dinariyana Dwi Putranta, Dhimas Widhi Handani : Estimasi Frekuensi Tubrukan Kapal Selama Proses Pembongkarang Pipa Bawah Laut Pada Crossing II Alur Pelayaran Barat Surabata (APBS)
Prof.Dr.Ir. Ketut Buda Artana ST., M.Sc.
A.A. BGS. Dinariyana Dwi Putranta S.T., MES, Ph.D
Dr. Dhimas Widhi Handani ST.,M.Sc
Seminar Nasional Teori dan Aplikasi Teknologi Kelautan (SENTA)
Surabaya West Access Channel (SWAC) is one of the busiest shipping channels in Indonesia. Currently, with the depth of shipping channel - 9m LWS and width 100 m, large vessels with deeper draft can not pass the channel. In order to increase the amount of cargo carried by larger vessels and to decrease logistic costs, PT. Pelindo III plans to revitalize the channel. The shipping channel will be deepened to - 16 m LWS and also be widened to 200 m. The revitalization project can not be conducted until subsea gas pipelines relocation process in the shipping channel is completed. One hazard that may occur during pipeline decommissioning process is regular ships collision to Diving Support Vessel (DSV) and pipelay barge that operated during the process. Hence, this study aims to proposed method of pipeline removal and also to determine the frequency of ships collision that pass DSV and pipelay barge during pipeline decommissioning process. There are two alternative methods of pipeline removal considered in this study namely, Reverse S-Lay and Cut & Lift. The selection is carried out using the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS), while the collision frequency is calculated using Quantitative Risk Assessment or CRASH Model and will be compared by using SAMSON Model that originally proposed by MARIN, Netherlands. TOPSIS selected Reverse S-Lay as a method for decommissioning the subsea gas pipelines. During the process of decommissioning pipeline with a reverse S-Lay, the annual frequency of powered and drifting collisions according to QRA are 0.1996 and 0.0001198 respectively. While according to SAMSON Model calculation, the frequency of powered and drifting collisions are 0.0159 and 0.00146. Due to the value of annual frequencies are less than unity (1) for both collision scenarios in both model, it can be concluded that the risks due to collisions during decommissioning pipeline are acceptable.