DNV has released crucial revisions concerning ballast water management practices for vessels operating in demanding water quality conditions, in light of the most recent advancements from the International Maritime Organization (IMO).
During its 81st session in March 2024, the IMO’s MEPC approved Resolution MEPC.387(81), which offers provisional advice for vessels navigating difficult water quality circumstances, and Circular BWM.2/Circ.82, providing recommendations for the temporary containment of treated sewage and/or grey water in ballast water tanks. This update outlines these subjects, covering details on the process of re-certifying a modified BWMP.
Interim guidance for ships operating in challenging water quality conditions (MEPC.387(81))
This guidance aims to support vessels in adhering to the BWM Convention and the D-2 discharge standard when a type-approved ballast water management system (BWMS) faces operational constraints or struggles to meet operational requirements under challenging water quality (CWQ) circumstances. This is applicable even when the BWMS has been correctly installed, operated, and maintained.
Challenging water quality (CWQ)
As per DNV, Challenging Water Quality (CWQ) refers to the natural intake of water with characteristics such as high total suspended solids or turbidity. Under CWQ conditions, the BWMS may face temporary operational issues, such as filter blockages, or may operate beyond its intended system limits. However, this guidance does not cover scenarios where a BWMS is non-operational due to reasons unrelated to CWQ, like technical malfunctions.
Such cases should be handled individually following the contingency measures outlined in the BWM Convention (BWM.2/Circ.62). It’s important to note that the interim CWQ guidance does not address instances where the temperature and salinity of the water intake exceed the BWMS design limits specified in the type approval certificate.
Amendments to the Ballast Water Management Plan (BWMP)
Vessels are required to incorporate protocols for handling Challenging Water Quality (CWQ) conditions within their approved Ballast Water Management Plan (BWMP). These protocols should be tailored to the specific vessel and take into account the operational constraints of the installed BWMS as well as the ship’s operating patterns.
They should encompass the measures outlined in MEPC.387(81) and detail the actions that the ship’s crew can implement to restore or sustain the efficient functioning of the BWMS when encountering CWQ conditions.
Resorting to by-passing the BWMS should be considered only as a last resort. In unavoidable situations where bypassing becomes necessary, only the minimum amount of ballast required for safety and operational needs should be taken up. Additionally, following any bypassing of the BWMS, the affected ballast tanks must undergo a “decontamination” process to regain compliance with the D-2 standard.
This involves replacing the untreated ballast water in each affected tank through a sequence of ballast water exchange, flushing, and final treatment using the BWMS.
The decision to apply the CWQ management procedures should be evaluated on a voyage-by-voyage basis. Even if CWQ challenges were encountered at a specific location in the past, an attempt to treat ballast water with the BWMS should be made.
CWQ conditions can vary between different berths within the same port or can be influenced by vessel and/or nearby port activities. Furthermore, CWQ conditions may change based on the time of day, tide, weather conditions, or season.
Guidance on the temporary storage of treated sewage and/or grey water in ballast water tanks (BWM.2/Circ.82)
This guidance aims to offer a protocol for the temporary containment of treated sewage (TS) and/or grey water (GW) in ballast water tanks. It also provides instructions on the necessary transition process from storing ballast water to storing treated sewage and/or grey water, and vice versa.
Compliance with the discharge of ballast water, TS, and GW should follow the following principles:
- the discharge of ballast water should comply with the BWM Convention.
- The discharge of TS should comply with MARPOL Annex IV where relevant. Any local TS/GW discharge requirements should be considered.
The Ballast Water Management Plan (BWMP) of the vessel must incorporate a customized transition protocol unique to the ship. This procedure should outline the pump, piping arrangements linked to the dual-function ballast water tanks, and offer precise instructions on the flushing process.
Approval of amended Ballast Water Management Plan (BWMP)
DNV suggests integrating the updated IMO guidance on managing challenging ballast water by modifying the Ballast Water Management Plan (BWMP). If temporary storage in ballast water tanks applies to the vessel, the new instructions regarding temporary storage of treated sewage and/or grey water should also be added to the revised BWMP.
While no flag administration currently mandates these amendments for existing vessels, Resolution MEPC.387(81) emphasizes the necessity for ships to be ready for challenging water quality (CWQ) conditions.
It is anticipated that flag administrations will enforce Resolution MEPC.387(81) in their forthcoming circulars or bulletins. Similarly, certain flag administrations may require amendments to the BWMP in accordance with Circular BWM.2/Circ.82. For new vessels, the BWMP should incorporate these updated guidelines.
Regarding the approval process, if an addendum or appendix is attached to amend the BWMP, ship owners/managers can voluntarily seek approval from DNV if DNV is authorized by the flag as a Recognized Organization (RO) for BWMP approval.
However, DNV considers that statutory approval of non-mandatory documents is typically not necessary unless specified by the flag administration. If an existing BWMP is entirely replaced with a new revised version containing new sections, DNV’s approval as the RO is essential.
DNV suggests integrating the updated IMO guidance on managing challenging ballast water by modifying the Ballast Water Management Plan (BWMP). If temporary storage in ballast water tanks applies to the vessel, the new instructions regarding temporary storage of treated sewage and/or grey water should also be added to the revised BWMP.
While no flag administration currently mandates these amendments for existing vessels, Resolution MEPC.387(81) emphasizes the necessity for ships to be ready for challenging water quality (CWQ) conditions. It is anticipated that flag administrations will enforce Resolution MEPC.387(81) in their forthcoming circulars or bulletins.
Similarly, certain flag administrations may require amendments to the BWMP in accordance with Circular BWM.2/Circ.82. For new vessels, the BWMP should incorporate these updated guidelines.
Regarding the approval process, if an addendum or appendix is attached to amend the BWMP, ship owners/managers can voluntarily seek approval from DNV if DNV is authorized by the flag as a Recognized Organization (RO) for BWMP approval.
However, DNV considers that statutory approval of non-mandatory documents is typically not necessary unless specified by the flag administration. If an existing BWMP is entirely replaced with a new revised version containing new sections, DNV’s approval as the RO is essential.
DNV suggests integrating the updated IMO guidance on managing challenging ballast water by modifying the Ballast Water Management Plan (BWMP). If temporary storage in ballast water tanks applies to the vessel, the new instructions regarding temporary storage of treated sewage and/or grey water should also be added to the revised BWMP.
While no flag administration currently mandates these amendments for existing vessels, Resolution MEPC.387(81) emphasizes the necessity for ships to be ready for challenging water quality (CWQ) conditions. It is anticipated that flag administrations will enforce Resolution MEPC.387(81) in their forthcoming circulars or bulletins.
Similarly, certain flag administrations may require amendments to the BWMP in accordance with Circular BWM.2/Circ.82. For new vessels, the BWMP should incorporate these updated guidelines.
Regarding the approval process, if an addendum or appendix is attached to amend the BWMP, ship owners/managers can voluntarily seek approval from DNV if DNV is authorized by the flag as a Recognized Organization (RO) for BWMP approval.
However, DNV considers that statutory approval of non-mandatory documents is typically not necessary unless specified by the flag administration. If an existing BWMP is entirely replaced with a new revised version containing new sections, DNV’s approval as the RO is essential.
Recommendations
Ship owners/managers are encouraged to familiarize themselves with the new IMO guidance on managing challenging ballast water and on the temporary storage of treated sewage and/or grey water. Owners/managers are encouraged to start preparing for implementation of these guidances by amending the BWMP for their ships.
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