Chain and Scraper Upgrades Help WWTP Meet NPDES Requirements

Challenge

The City of Los Angeles’ Hyperion Wastewater Treatment Plant is one of the largest in the United States. It serves approximately 9 million people by treating 460 mgd of wastewater.

Built in 1949, the plant was designed to treat up to 450 mgd but was forced to reduce secondary treatment in the 1960’s to 120 mgd due to limited secondary capacity. The city faced numerous challenges:

• a growing population
• an increasing amount of sewage produced
• aging plant equipment
• a mix of components from various manufacturers

With a governmental directive to cease ocean discharge of sludge by 1987 and provide secondary treatment to all wastewater by 1998, the city turned to Evoqua to make the necessary changes.

Los Angeles Hyperion Wastewater Treatment Plant

Solution

Evoqua Water Technologies had previously worked with the city (as well as with plant personnel) in supplying 11 chain and flight sludge collectors for the plant’s three primary treatment facilities in 1987.

For its assessment of the secondary treatment facility, Evoqua worked with local consulting engineer and Hyperion personnel to evaluate the loads experienced by the collector chains and predict the wear resistance and overall strength of new alternatives.

After careful analysis, we suggested installing Envirex® HS730 high-strength collector chains for their nine primary sludge collectors. This collector chain is the only high-strength, nonmetallic design with a working load of 4,500 lbs and a minimum ultimate tensile strength of 20,000 lbs.

As well as being compatible with many of the lower capacity chain components already in place, the nonmetallic design has saved considerable maintenance staff hours and reduced both the number of personnel needed and the time required to maintain the primary collector systems.

Results

• The Hyperion WWTP has consistently met all NPDES requirements since the upgrades.
• Reduced the amount of wastewater solids entering Santa Monica Bay by 95%.
• Improved the quality of life for marine, avian and mammalian residents.

Awards:

• 2003 National Environmental Achievement Award for production of Exceptional Quality (EQ) Biosolids from the Association of Metropolitan Sewerage Agencies (AMSA).
• 2000 Superior Achievement in Environmental Engineering Excellence from the American Academy of Environmental Engineers.
• 2001 Top Ten Public Works Projects of the 20th Century from the American Public Works Association.
• 2001 Top 125 Projects in the Construction Industry from Engineering News Record Magazine.​