Three incompatible blocks in one 40 ft box
A consolidator is stuffing a 40 ft container (internal length about 12.03 m) for a short-sea sailing. The load plan shows three blocks: 100 x 25 kg bags of UN 1689, SODIUM CYANIDE, Class 6.1, PG I, on 20 pallets; 20 x 200 L drums of UN 1789, HYDROCHLORIC ACID, Class 8, PG II; and 40 x 25 kg drums of UN 2880, CALCIUM HYPOCHLORITE, DRY, Class 5.1, PG II, two of which are showing damp staining. The planner's sketch puts the cyanide at the door end, the acid drums in the middle, and the hypochlorite against the forward wall, and notes that the container will be stowed under deck, two bays from the accommodation, because the deck is full. The planner says: "It is all in one box, so segregation does not apply - the 3-metre rule is only for deck stowage."
1. Does segregation apply inside a single container? Explain how the requirement is worked out for these three consignments.
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Yes. Segregation applies to dangerous goods within a cargo transport unit just as it does on deck; the container is not a magic box that cancels incompatibility. The method is the same as for the ship: read each entry's segregation provisions in the Dangerous Goods List, apply the segregation table, then apply the segregation group rules in the Code (acids, cyanides, hypochlorites and so on), which exist because the chemical reaction, not the class, is the hazard.
Here sodium cyanide is in the cyanide segregation group and hydrochloric acid in the acids group; the group table requires them to be separated from each other. Acid plus cyanide liberates hydrogen cyanide, which is lethal. Calcium hypochlorite is in the hypochlorite group and is also an oxidiser; acid plus hypochlorite liberates chlorine. So acid against both other blocks is a separation requirement, not a preference.
In practice, "away from" is read as about 3 m horizontally and "separated from" as about 6 m, with the goods not able to interact if one leaks. The planner has the three blocks adjacent, so nothing is achieved.
2. What must change in the load plan before stuffing can proceed, and what do you do about the damp hypochlorite drums?
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The damp drums come out first. Damp staining on a hypochlorite drum means a leaking or deteriorating package and possible contact with a substance that can start a chlorine-releasing reaction; the drum is not fit for shipment and must be overpacked, repacked by a competent person, or rejected. It does not get loaded "because it is only damp".
Then the plan: the simplest compliant solution is to split the three blocks into separate containers, which is what most consolidators do once an acid and a cyanide are in the same booking. If they stay in one 40 ft unit, the acid must sit at least 6 m from both the cyanide and the hypochlorite with intervening cargo, not merely a different corner, and the arrangement must be justified on the packing certificate. Liquids should not be stowed above the bags. The 5.1 oxidiser should also be checked against the Dangerous Goods List stowage category - under-deck stowage two bays from the accommodation may itself be restricted, and the deck being full is not a reason to ignore column 16a.
Finally, whoever signs the container packing certificate is certifying this arrangement. The planner's sketch cannot be signed as it stands.
3. During stuffing, a hydrochloric acid drum is found leaking. Set out the immediate response and the reporting obligations.
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Stop work, clear and secure the area, and approach only with the personal protective equipment and response information for the substance - acid burns and the fumes are the immediate hazards. Consult the EmS Guide entry for the consignment (acid, Class 8) for spillage and fire guidance before doing anything clever. Contain the leak, keep it away from the cyanide and the hypochlorite, and keep it out of drains and the water; do not use water in a way that spreads acid onto the other cargo or generates gas.
Do not ship the leaking drum. It must be repacked or overpacked under supervision, the container cleaned, and the hold/terminal area checked before work resumes. Notify the terminal, the port authority and the line's dangerous goods adviser, and record what happened and what was done.
Reporting: incidents involving dangerous goods and marine pollutants must be reported to the relevant coastal state and the flag using the standard reporting format in the IMDG Code supplement, and MARPOL Annex III carries a parallel obligation for marine pollutants. A near miss on the quay is exactly the kind of event that should be captured and investigated, not filed as "drum replaced".