Storm sewers, which collect runoff from rainstorms and melting snow, are kept separate for nearly all the County. This results in much higher inflow during and after major storms. Most of the system is gravity propelled. This is the cheapest, most reliable power source for the collection system. Corrosion is always a concern with sewer pipes.
Corrosion tends to happen because the organic material in the sewage gives off hydrogen sulfide.
The hydrogen sulfide reacts with water to form sulfuric acid. The acid eats away at the pipe, eventually forcing repair or replacement. Mission Statement Environmental Policy Frequently Asked Questions Treatment Process Dealing with industrial wastes About the sewer collection system About pumping stations About Delaware No. 1 Water Pollution Control Facility Diagram of Delaware No.