While at sea, Matson’s vessels manage any water discharges in accordance with stringent environmental standards. If liquids do not meet the discharge standards, they will be retained on board until they can be pumped ashore for proper disposal. Water systems on the vessels include the following:
- Ballast water holding tanks
- Bilge water holding tanks with Oil Water Separators (OWS)
- Potable water tanks
- Graywater and blackwater (sewage) tanks
- Exhaust gas cleaning systems
Bilge water is water runoff from decks and interior vessel spaces, which may contain oil. Effective treatment must be used to prevent ecological harm from bilge water discharges. Matson has installed oil water separators equipped with an oil content meter on all vessels in compliance with IMO and USCG regulations.
To help protect the coastlines of the communities we serve, Matson established the “Matson Environmental Protection Zone” (MEPZ) in 2002. The MEPZ is the sea area within 50 miles from the nearest land. When a Matson vessel is within the MEPZ, procedures prohibit any discharges through the OWS, even though regulations allow discharge closer to shore. Matson similarly does not discharge sewage without use of an approved marine sanitation device, even outside of the MEPZ.
Matson operates two types of exhaust gas cleaning systems: hybrid (open/closed-loop) and open-loop. The hybrid units can be operated in the open-loop mode at sea where regulations allow and are switched to a closed-loop mode near shore. Closed-loop scrubbers spray fresh water treated with sodium hydroxide into the vessel’s exhaust system and then collect and treat the washwater to neutralize harmful compounds. The removed waste products are discharged ashore for appropriate disposal so there is no discharge to sea. Open-loop scrubbers use seawater to scrub the vessel’s exhaust of sulfur and particulate matter, then discharge the seawater. Matson complies with all IMO and national requirements regarding the discharge of open-loop scrubber discharge water.