High Water: Pumping It Out?

I spotted a couple of Casella Waste Management tanker trucks this evening by the Plattsburgh sewage treatment plant. With the lake being so high, water right up to the plant's walls, I'm wondering if the city has to pump out the facility and transport the load to who-knows-where. If that's the situation, then more costs for the city from the flooding.

(On second thought maybe the tankers aren't pumping but dumping. I must admit my lack of knowledge with sewage treatment plants.)