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Successful removal and dredging of rock in India having a Mega Pascal value over 50 was something we decided to boast and celebrate. Mormugao Port Trust considered and certified Jaisu Shipping Company's job done as "EXCELLENT WORK". In their own words "In addition to contracted work, Jaisu Shipping Company Pvt Ltd. have successfully dredged additional quantities of hard soil and about 13,500 CuM of rock (compressive strength up to 52.50 Mpa) by their multi bucket dredger 'KAMAL XXVI' as extra item. They have also removed obstruction encountered during execution of dredging work so as to achieve required design depth."
The work at Tuticorin Port is another milestone. The subject of dredging the Port and related areas has been in long association with Tuticorin Port. The idea of extending port's breakwaters to nearly 4 km from the shore was in pursuit of ocean depths to handle the medium and large size vessels of the world's merchant fleet. Dredging of port areas has been emphasized right from the Government level for economical operations of sea ports. Whenever the port authorities met with hard rocks having higher compressive strengths, the process of pre treating the sea bed was resorted to by breaking the rock mass into fragmentations before resorting to grabbing. Hostile marine conditions like intense wave actions and the sea areas closer to existing rigid marine structures like breakwaters, wharf and jetty structures do also warrant loosening up the sea bed to desired depths.
Underwater blasting is often resorted to on such occasions to fragment the hard sea bed. Shaped canisters filled up with explosive are used world wide depending on the depths and the distance between centre of explosion to nearby structures for blasting operations. Various institutions are involved in recommending safe charge determinations for blasting operations. The present and old veterans have worked in this field for dredging the bed rock at Tuticorin Port. The sea bed at Tuticorin presents a peculiar problem in tackling the capital dredging and the Port had to wait for more than a decade to arrive at the right type of methodology and equipment to dredge the channel and berth areas. Earlier, the assistance of CWPRS, Pune was obtained to arrive at the safe charges. Drilling & blasting was also resorted to in working at restricted areas to provide the foundations for sea walls.
The dredging of dock basin (area of 1.50 lakh sq.m) in front of 8 th berth was included as an optional item in the original contract concluded with M/s JAN DE NUL, Belgium to dredge upto -11.9m level. But this dredging could not be completed by their cutter suction dredger owing to their finding of the area to be much harder having more compressive strength and this optional item was left over. Subsequently it was proposed to adopt conventional method of drilling, blasting and dredging and as per regular tender procedure this dredging work is awarded to M/s Jaisu Shipping Company Ltd., New Kandla at a negotiated cost of Rs.42.81 crores, against the estimated cost of Rs.46 crores. Now the dredging works are in progress.
The 8 th berth was constructed and commissioned during February, 2002. The draft available in front of the berth is only 7.00m. In order to match the draught of other berths in the Port, it was decided to dredge this berth also to 11.90 m depth to cater to 10.70 m draught vessels. The work of dredging 8 th berth at a cost of Rs. 42.81 Crores was awarded to M/s Jaisu Shipping Company (Pvt) Ltd., Kandla, an Indian Contractor. The work commenced during July, 2002. The period of contract is 7 months.
General Working Principle:
The rock break Multi Bucket Dredger "KAMAL-XXVI" is a special type of dredging equipment. The main components of Rock break Bucket Dredger are as follows :
- The Pontoon
- Bucket Ladder
- The control bridge
- Diesel & Electronic propulsion of two Nos 1250 Hp each
- Hopper with side chute
- The side wires.
The rock breaker is attached with moving ladders. There are 84 buckets of each 0.77 cum. This can be operated for 24 m depth. The rock bucket itself is a cutting edge. While movable buckets with materials it cuts and collects the materials in the bucket. The movable buckets dump the materials in the Hopper provided at the top of deck. During the course of dredging the dredger moves with its anchor. Buckets are capable of breaking soft rock, slate stone and pretreated rock. The average output/day is 16,000 cum. The filled up material is being discharged into the barge through the side chute.
Disposal of Dredged Materials:
M.V."APSARIKA" and M.V."SAHAYAK" self propelled Hopper barges of 1250 T capacity each are moored along side of the dredger and after the barges are loaded they sail to the designated dumping site and dump their loads. In order to provide continuous dredging operation, these two barges are cyclically operated for loading and dumping. Our high powered Tugs "RUBY-III" and Tug "TOPAZ" are assisting the dumb barges. "KAMAL-XXIII" and "KAMAL-XXIV" deck loading barges used for carrying dredged material for reclamation purpose to designated reclamation ground.
The Port has earmarked two dumping locations for disposing off the dredged materials, one is located nearby the shore for about 240 m x 160 m and another one is located parallel to the TTPS conveyor system for about 1680 m x 60 m width. The dredged materials are unloaded from these barges by using machinery like Excavator / Dozer mounted on barge.
Thus making the process less complicated and a big success.