Sodium Hypochlorite Storage Tank Replacement

Owner:

West Basin Municipal Water District

Location:

El Segundo, California

Value:

$1,137,000

Completion:

2021

Contractor:

Tharsos Inc.

Designer:

Tetra Tech

Butier Engineering, Inc. provided construction management and inspection services for the replacement of the existing sodium hypochlorite (SHC) storage tanks. The four tanks, which are located at the Edward C. Little Water Recycling Facility (ECLWRF), are approximately 29,000 gallons each, 12-foot in diameter, 30-feet tall, and made of fiberglass reinforced plastic (FRP) materials. The existing tanks reached their useful life and were replaced with four new FRP tanks. The demolition and installation were sequenced so that Tank 04 was kept in service until the new Tanks 01 and 02 were constructed and brought on-line. The scope of work consisted of the following:

• Demolition of the existing tanks
• Saw-cutting and replacement of the concrete tank pad with a new concrete foundation in accordance with updated seismic requirements
• Construction of a new isolation valve
• Installation of the four new FRP tanks and the interconnecting piping between tanks

The fabrication was performed under a separate contract with West Basin and An-Cor Industrial Plastics. The tanks were fabricated according to ASTM RTP-1 standards with RTP-1 tank certification and stamp. Therefore, An-Cor self-certified all the QA/QC results. Butier provided a review and evaluation of these QA/QC test results and provided visual inspection of the tanks when they arrived at West Basin’s ECLWRF. The inspection consisted of ensuring the structural integrity and confirming the existence of the interior corrosion barrier consisting of 120 mils minimum of C-glass veil. The presence and structural integrity of the corrosion barrier is essential for the tanks to function properly and last 10 to 15 years.