Challenge

A West Coast refinery relied on Siemens mobile clarification to treat the wastewater in their retaining pond.  Adjacent to San Francisco Bay, the fixed-capacity pond accumulates biologically treated waste for further treatment prior to discharge.  With heavy winter rainfall, the 105-acre pond had become dangerously close to overflowing.

An overflow would have resulted in a violation of the refinery's NPDES permit, leading to stiff fines and negative publicity in the community due to intense scrutiny by third-party environmental groups.  As a good corporate citizen, the refinery believed it important to prevent an overflow to protect wildlife and fish in the neighboring marsh and bay.

Solution

Siemens supplied the refinery with an emergency mobile clarification trailer and onsite operating personnel.  The clarifier provided the extra water treatment capacity needed to reduce the level of water in the pond.  The refinery's existing wastewater treatment system was able to process 5,000 gallons per minute (gpm) of pond water.  The mobile trailer would increase treatment capacity by 20 percent, or an additional 1,000 gpm.  This added capacity was designed to reduce the level of the pond, creating more freeboard as a safety factor.  One full day's treatment at 6,000 gpm would drop the level of the pond by one inch.  The refinery's goal was to maintain a level 24 inches below the overflow point.

The mobile solution provided a high-volume clarification system that could be placed into operation rapidly, fit within the space constraints of the refinery, and minimized refinery manpower in the wastewater area.  The mobile clarifier's footprint is one-tenth that of a standard clarification system treating similar flow volumes.  With Siemens providing full operational support, the refinery dedicated no additional manpower beyond the initial hookup support.

Results

The mobile clarifier provided consistent quality product water that met the NPDES permit, despite the rapidly changing water quality.  The customer used the trailer for two months during the rainy season to ensure that the pond was maintained at a level that is safe for the environment.

Mobile Clarification for West Coast Refinery