Dismantling, removal, towing of Power Barges TIGER-I & TIGER-III and loading onto Semi-submersible vessel HUA XING LONG

Khulna Power Company Limited (KPCL) owned one 110 MW Barge mounted Power Plant consigning of two power barges each producing 55 MW power. These barges each had a dimension of 91.44m × 24.40m and had a moulded draft of 5.5m. These barges were housed in a specially made basin at Goalpara, Khulna on the bank of river Bhairab. The basin was protected with 30m sheet piles. The river bank was specially protected with farther sheet piles and containers loaded with concrete were embedded in the ground, so that no erosion can damage the basin.

There were 19 (Nineteen) Chimneys, each having height of 26.44m and we had to cut down 16.88m of the Chimneys and load them inside the barges. TIGER-III had 10 (Ten) Chimneys and TIGER-I had 9 (Nine) Chimneys. We also had to remove flexible raw water pipes, raw water pumps, panel boards, pipes & back washing equipments, transformer, bridges, ramps and reload them on barges. Grid lines were also disconnected. All spare parts were Boxed, Catalogued, Data based and were loaded into the barges.

Documentation

The barges were first Commissioned in 1998. De-Commissioning and re-exporting after 24 (Twenty Four) years were a challenge both documents and operation wise.

We had to get clearance / NOC’s from the following departments:

–          Bangladesh power Development Board -IPP, Estate and Finance

–          Chief Controller of Import & Export (CCI&E)

–          Bangladesh Bank

–          National Board of Revenue (NBR)

–          Bangladesh Inland Water Transport Authority (BIWTA) 

In most departments original import documents were not available and we had to prepare duplicate documentation and get them approved. Additionally, we had to get endorsed the new Buyer-Seller Agreements by various department and got them approved. Arranging re-exports of two power barges after 24 (Twenty-Four) years of import and in absence of all original documents was a real challenge and Avant did that successfully.

Operation

Work scopes and sequence of activities were planned in consultation with KPCL for safe and smooth operation and finally delivery in accordance with the schedule of Semi-submersible vessel.

The following equipment were used in the operations

1. 3200 HP Tug boat x 2

2. 2400 HP Tug boat x 1

3. 1600 HP Tug boat x 1

4. Observation vessel x 1 (THE SAIL)

5. Anchor barge x 1

6. 90 Ton Crawler crane x 1

7. Long and short boom excavators x 3

8. Vibratory hammer with power pack -1

9. Winch, chain pulley all others equipment and tools – 1 lot

10. Manpower involved – about 150

Avant mobilized all required equipment to shore. The crane was mobilized to the East bank of the Basin to hold the Chimney top. Gas cutting team cut the Chimneys at desired level and the cut portion of Chimneys were loaded onto barge deck. All 10 (Ten) chimneys of TIGER-III were cut accordingly and loaded inside the barge. Meanwhile KPCL conducted Plant Load Test with the Buyer. Long and short boom excavators were engaged in excavation and dismantling of wall across the East-West perimeter on the premises.

Water level of the river was taken as standard in excavation to maintain such a bed level so that the first barge moved out at 7.0m of water depth against the barge draft of 5.5m. Additional 1.5m excavation was done so that there was no draft problem during movement of the barges. Extreme care was taken so that the barges were not damaged. Avant kept 5m wide strip on the river bank so that no water entered the excavating pockets. 18 nos. of sheet piles were removed first and then 80 nos. of sheet piles (30m) were removed later.

Once sheet piles were extracted, water from the river entered the excavated basin. At this stage, TIGER-III was pulled to the excavated basin and simultaneously TIGER-I was pulled to East bank where TIGER-III was floating earlier. TIGER-I coming under the reach of the crane, the 9 (nine) Chimneys on TIGER-I was cut and the cut portions were loaded inside TIGER-I.

TIGER-III already in the river was towed by Tug boats to Mongla port by 1×3200 BHP Tugs and 2×2000 Tugs. On reaching Mongla port TIGER-III was moored with the port buoy and Tug boats were sent back to KPCL plant to bring TIGER-I. The Tugs, by the same manner followed earlier to tow  TIGER-III, now pulled TIGER-I out of the basin and brought the barge to Mongla port. Utmost care was taken while crossing Rupsha Road and Rupsha Rail bridge (under construction). Customs Clearance was done while both the power barges were stationed at Mongla port.

After Customs Clearance was completed, TIGER-I was Towed to Akram point, 60km further into the sea where the Semi-submersible vessel HUA XING LONG was berthed. It needed 25m of draft to go down into the river to load the power barges. Draft, tide, weather and wind had to be synchronized to load the power barge into semi-submersible vessel. It was a very difficult operation and TIGER-I was loaded on the second attempt. Once free, all tugs boat went back to Mongla port to bring TIGER-III and TIGER-III was loaded into the semi-submersible vessel after three attempts.

We have attached pictures of this operation herewith.