US Coast Guard concerned about DPF installations on California harbor craft vessels
4 March 2024
In a letter to the California Air Resources Board (CARB), the US Coast Guard expressed safety concerns over the CARB requirements to install diesel particulate filters (DPF) on certain commercial harbor craft vessels such as tug boats.
In March 2022, CARB approved amendments to the Commercial Harbor Craft (CHC) Regulation, which require “zero-emission options where feasible” as well as the use of CARB-verified Level 3 particulate filters (Tier 3 + DPF or Tier 4 + DPF) on affected vessels. The DPF requirements are phased-in from 2024 to 2031, depending on the type and model year of the vessel. The first DPF compliance deadline for certain categories of tugs and ferries is December 31, 2024.
The California marine industry has been opposing the CHC regulation, arguing that the DPFs required by CARB have not been Coast Guard approved nor certified by the American Bureau of Shipping and other classification societies and may present a safety hazard for marine crews. The two key safety concerns included fire hazard due to the high exhaust temperatures during DPF regeneration and potential navigational safety issues in case of a DPF failure (blockage). In August 2023, the American Waterways Operators (AWO) wrote a letter to California Governor Newsom, requesting that CARB reconsiders the DPF requirements.
One outcome of the dispute has been a CARB’s concession that allows the use of safety bypasses of diesel particulate filters. While CARB has generally not allowed bypasses on verified emission equipment, the agency has recognized that in the marine environment, if propulsion equipment fails, a vessel may not be able to receive emergency assistance as quickly as land-based equipment. In a letter to the US Coast Guard dated November 13, 2023 CARB outlined the conditions under which a safety bypass system may be installed on a marine vessel.
However, the Coast Guard—an agency responsible for marine safety regulations and vessel inspection laws—remains concerned about the potential fire safety issues related to the use of DPFs in marine applications. In a letter to CARB, dated February 21, 2024 and signed by Rear Admiral A.M. Sugimoto, the Commander of 11th Coast Guard District, the Coast Guard cautioned about potential safety issues with DPF operating temperatures and the fire load of the vessel.
“Coast Guard regulations do not explicitly address DPF installations onboard commercial vessels,” says the letter to CARB. “Please note that DPFs verified by CARB may not necessarily be accepted by the Coast Guard for installation on inspected commercial vessels.”
By statute, each vessel has to demonstrate federal regulatory compliance, and it is the engine manufacturer’s responsibility to ensure that the engine systems are certified by the US Environmental Protection Agency for marine use and the applicable emission standards. The Coast Guard’s inspectors will not perform emissions tests, the letter says, and therefore the Coast Guard will not enforce California’s DPF regulations.
Source: The Maritime Executive