We also found that oil in API2 outlet which had sewer as a feed had high oil content as well. Sewer is oil contaminated water from pump drainage, emergency leakage, equipment cleaning, etc. discharged to underground sewer line. From the situation above, how would you, as a chemical engineer of ETP, solve this problem? Write your thinking process and all possible causes you can think of and the reason why it could be the root cause. Assume that you can acquire all information that you need first, then we will discuss after you send me the first draft of your process thinking.