A chemical manufacturing plant had two sewer systems, a storm sewer and a process sewer that were in the past combined into a single sewer. Years later, added development caused the combine flow of the sewer exceed the design capacity of the treatment system during some storm events.
An investigation of the feasibility of separating at least a portion of the storm sewer was conducted. As no as-built copies of the complete sewer system were available, each manhole and source had to be mapped out.
After a complete update of the sewer maps, it was discovered that a neighboring property that was allowed to tie into the system also recently built a large warehouse that tied into the system. It was this stream, that was diverted to a new storm sewer system.