Environmental Engineering Reference
In-Depth Information
cargo transfers and the concept of standard fi ttings is embedded in ship design and
construction. Therefore, for these vessels ballast water transfer to a reception facility
could easily be achieved provided the cargo transfer pipes may be used for ballast
water discharge. Hence, ships planning to use this option need to have adequate
equipment installed.
It should be noted that prior to the introduction of double hulls and segregated
ballast tanks, designed to minimize the threat of oil pollution to the environment,
tankers pumped their ballast ashore. Refi neries worldwide have ballast water recep-
tion facilities. Major crude oil exporting ports, such as Valdez (Alaska, USA) and
Scapa Flow (Orkney Islands, United Kingdom) still use these shore-based facilities
for the reception and treatment of oily ballast from crude oil tankers. This proves that
the engineering, pumping, storage etc. of massive quantities of ballast is technically
possible and economically feasible within the operating cost structures of modern
shipping and ports. Adapting this approach to include biological treatment to
remove or render harmless the ballast water organisms is unlikely to be any more
challenging or less feasible than the original development of these facilities -
especially as technology has advanced.
Land-based ballast water reception facilities may also be used to provide biologi-
cally clean ballast water at the source ports, which prevents the problem already at
ballast water uptake.
Sediment Management
Regulation B-5 of the BWM Convention requires that all ships shall remove and
dispose ballast water related sediments in accordance with the vessels' ballast water
management plan.
All possible practical steps should be taken during ballast uptake to avoid sedi-
ment accumulation, but it is known that it cannot be avoided to take sediment on
board and this will settle on tank surfaces and bottoms. The sediment amount in a
ballast tank should be monitored on a regular basis. When sediment has accumu-
lated, tank bottoms and other surfaces should be fl ushed when in suitable areas,
i.e. areas complying with the minimum depth and distance requirements as described
for BWE.
The frequency and timing of sediment removal depends on several factors,
including dimension of sediment build up, ship's trading pattern, availability of
reception facilities, work load of the ship's personnel and safety issues.
The removal of sediment should preferably be undertaken under controlled
conditions in a port, at a repair facility or in a dry dock. The removed sediment
should be disposed of in a sediment reception facility in line with the waste disposal
requirements of the coastal state. Regulation B-5 further requires that ships con-
structed in or after 2009 should, without compromising safety or operational effi -
ciency, be designed and constructed to minimize the sediment uptake and entrapment,
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