I inherited a contaminated fuel problem many years back on Natuna Island in Indonesia but in our case the fuel was discoloured. We had 7 Puma and 2 HS748s being fueled. It turned out the yellow colour was from using Avgas bladder tanks and hoses to store the turbine fuel. The amount of fuel was a few tons. Samples of 50 litres were sent to a fuel specialist lab in Singapore who gave a fast reply saying the fuel met all specs and was usable. Unfortunately they stamped every page of the analyses that they could not be held responsible for applicability of results and so I was forced to condemn the fuel. One of the oil companies drilling offshore claimed they used the scrapped fuel to de-wax a hole they were working on.