If a pipe carrying a slurry of ore and water leaks, you have ore in solid small lumps or grains which should be fairly easy to pick up, and water which will just drain away. As far as I know chromite ore is quite inactive, and shouldn't pollute rivers or be dangerous. Some while ago I read a report of an assesment on a proposed storage site for chromite ore imported to the US, and that stated no environmental threat was seen, as the ore is quite stable chemically, and doesn't react to exposure to weather. Some other ores do leach acid when exposed to weather (ie rain) & I don't know if this is the case with the NOT ore.