Hi, thanks for letting me join. I am working on an environmental topic for a state agency.
How common is it in the US, especially on the west coast, to use cargo tanks (e.g., petroleum products) as ballast tanks? I have heard that it is no longer very common. Can someone point me to a reference for what it now the standard practice? Thank you.
The law now is ballast being run through an Approved Ballast Water Treatment System for both loading and discharging. Don’t believe cargo/fuel tanks are being used anymore in US waters.
It’s still loaded occasionally. We’ll load storm ballast in cargo tanks for heavy weather, or in some instances when requested by the terminal in Valdez.
“Clean ballast tankers” are no longer a thing. All tankers are segregated ballast, which is required to be treated as Serpico mentioned.
There is currently no method of treating storm/dirty ballast.
Except running it through the ODME.
I meant in terms of treating for NIS in the same way seg ballast is treated.
Yea, I realized that after I hit send lol.
The MARPOL Conventions & OPA 90 Are good places to start
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uhhhh… for some it may be too much even to consider . 
Does anyone remember that old poster showing a mate watching ballast discharge overboard through a hose over the rail?
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I never really dealt with ballast until BWTS became more prevalent, but even then that wasn’t related to cargo ballast. As a slave to the OCM for bilge water, I always understood the ODME as the physical manifestation of “the solution to pollution is dilution.” Am I wrong in understanding that an ODME just spreads out a contaminated discharge over a calculated distance and total volume of sea water? It’s not held to the same PPM standard as bilge water right?
Yeah, 30 l/nm. There’s also a total oil discharge limit- 1/30,000th of your last cargo.
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15 ppm. It’s way more restrictive than the OCM.
15 ppm is the limit for machinery space OWS/oil content meter (OCM) overboard discharge.
My bad. I thought it was 50.
The OCM can be run much closer to shore, and as far as I can remember, there aren’t the limits placed on it like the ODME.
It’s been 15 for machinery spaces as long as I can remember. Though I believe there are some type approved 5ppm OCMs now.
getting your ows to maintain 15 ppm is rough … hot water flush for it works wonders but is a hassel. ballast discharged in port has to go thru the shore facility and costs money !!! (whether from ballast tanks or fuel tanks. )