Pump Room Overflow

Overflow System to Prevent Flooding

Like most historic paper mills, this facility is located on a river and includes a dam. The raw water pump room consists of a penstock pipe hydraulically connected to the upstream side of the dam, which gravity feeds through a number of screens into a reservoir near the downsteam river elevation, from which water is pumped to locations around the mill. During power failures, if the pumps stop taking water from the reservoir before the screen isolation valves can close, the room experienced flooding. The purpose of the project was to construct an overflow weir from the screened water reservoir so that even at high upstream water levels, water would not overflow into the pump room during a power outage. LHB evaluated the hydraulic conditions of several weir configurations and designed a system that conveys water into a new chamber in an adjacent building. The collection chamber includes a flap gate that leads to a channel connected to the downsteam river elevation. The flap gate prevents the downstream river from backing into the chamber during high water conditions. The system has a design throughput of approximately 24,000 gallons per minute.