India: Dabhol LNG Project Includes Dredging
As part of revival and restructuring of the Dabhol project, M/S GAIL INDIA Ltd and M/S NTPC Ltd have formed a joint venture company, named Ratnagiri Gas & Power Private Ltd (RGPPL) to complete the balance work at the power plant and LNG terminal.
The entire facility is located Anjanvel, Dabhol, about 340 km by road to south of Mumbai. RGPPL has appointed Gas Authority of India Ltd (GAIL) as owners Engineer and in turn GAIL India Ltd has appointed Engineers India Ltd (EIL) as a project Management Consultant (PMC) for overall execution of the job.
As part of the revival project both soft and hard dredging needs to be carried out to a desired depth of 14.5 m from the chart datum for the approach channel including turning basin of the RGPPL port of Dabhol.
Revive the LNG terminal off Dabhol characterised by an approach channel of 8 kms and a turning basin for Ratnagiri Gas and Power Pvt LTD (RGPPL).
Removal of soft silts and soft rock (loose rock boulders, stiff clay, and weathered rock) so as to achieve a depth of 14.5m below CD. Dredging the approach channel, turning basin and near existing jetty for removal of soft silt and soft rock to achieve the 14.5m depth below CD.
Soft soil removal quantity is 5.15MM3 and rock is 45,500 M3. Dharti Dredging and Infrastructure Ltd the Indian Dredging copany deploys Trailing Suction Hopper Dredger (TSHD) ‘’Josef Mobius’’ having hopper capacity of 5,500 m3 and capable of dredging up to 25m, and a grab dredger “Pandora” having 20 m3 bucket and 50 T drop rock breaker (chisel shape) with 60m dredging capacity. TSHD to dredge in the soft soil areas and grab dredger to remove rock patches.
Work includes a detailed hydrographic survey to ascertain actual sea bed and rock profiles in the dredging area using following equipments:
• Single beam echosounder;
• Multi beam echosounder;
• Side Scan Sonar;
• Shallow Seismic Profiles.
Removal of soft soil through TSHD and transported to offload at designated offshore disposal located 10 km form the dredging location. Surveys conducted regularly at disposal area to confirm dumping done as per specifications of employer. Removal of rock embedded in the stiff clay using grab dredger and loaded in to the split bottom hopper barges.
Tugs towed fully loaded hopper barges to the dumping location and offloaded at designated offshore dumping location. Rock boulders of bigger size (greater than 5 m3) also removed. Dharti Dredging and Infrastructure Ltd completes project in compliance with high standards of safety.
Press Release, May 31, 2013