Hyperion Wastewater Treatment Plant

"Permitting, Modeling and Testing New Scrubber Systems"

What's the most effective way to monitor numerous odor abatement and emissions control scrubber systems at one of the largest wastewater treatment plants in the United States?

That has been MWH's objective on an extensive renovation program for Hyperion Wastewater Treatment Facility in Los Angeles. In an effort to maintain thorough treatment of all waste entering the plant, the facility has installed several scrubber systems to handle the increased capacity.

As the prime contractor, MWH is responsible for permitting, modeling and testing the scrubber systems.

Modeling and Permitting

MWH is currently conducting a health risk assessment on the primary treatment hydrogen sulfide scrubbing system. This assessment is required by California's South Coast Air Quality Management District (SCAQMD) in the permitting process.

The Hyperion scrubbing system consists of six 20,00-cfm caustic scrubbers, followed by 12 carbon bed vessels — two per scrubber. As required in SCAQMD Rule 1401, MWH conducted dispersion modeling of the hydrogen sulfide emissions to assess the potential for exposure at the property line and nearby residents.

Using reference exposure levels (REL) defined by The California Office of Environmental Health Hazards Agency, MWH calculated the potential acute and chronic hazard indices. These maximum hazard indices were developed for both commercial and residential requirements.

Emissions Testing

MWH is currently assessing and quantifying emission reductions associated with the installation of a new vapor control system on the facility's Intermediate Pumping Station (IPS). The new IPS vapor control system consists of two 20,000-cfm scrubbers. These scrubbers replace an older 5,000-cfm system. They are designed to control odor, hydrogen sulfide and volatile organic compound emissions from the IPS influent and effluent bays.

Working closely with the SCAQMD, MWH employees are developing a systematic approach to quantify both fugitive and point-source emissions associated with the decommissioned and newly installed scrubber systems.

MWH is using an unique tracer gas approach to quantify fugitive emissions, and standard EPA and SCAQMD sampling methods to quantify point source emissions.

Data gathered from the project will be used to conduct a health risk assessment on the new vapor control system. At the same time, Hyperion officials expect program results to yield significant potential savings to the City of Los Angeles in both capital and O&M costs.

Learn more about this project.