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To treat odors associated with two of the City's largest interceptor sewer systems the City of Los Angeles has been testing various odor control strategies for several years in order to develop the most cost-effective approach. The Air Treatment Facilities (ATF's) for the interceptors are located in the public right-of-way and therefore safety concerns played a major role in process selection. After careful evaluation of alternatives, Bio-trickling filters (BTF) were selected as they do not require the use of chemicals.Initial testing at the test facility located at the Hyperion Treatment Plant was conducted on a fullscale, single stage bio-trickling filter followed in series by a bench-scale polishing stage consisting of either a Biofilter or carbon adsorption unit. These test results indicated that at the selected ATF locations the odor levels remaining after first stage treatment were too high for direct atmospheric release and that a polishing stage was required. Furthermore, air modeling indicated that only the use of activated carbon as the polishing stage would reduce odor levels to targeted goals.Based on the information gained from these initial tests, a 2-stage odor control system employing bio-trickling filter technology followed by carbon absorption was selected for the City's ATF's. In an effort to improve the BTF performances, a new media manufactured by Taiwan-based Matala Water Technology has been tested. . Under a joint effort between Envirogen Technologies, Inc. and the City of Los Angeles, Matala media was placed inside a BTF manufactured by Envirogen Technology. The installation of this unit, located at the Hyperion Treatment Plant, was completed at the end of May 2008. Testing was performed over the following seven (7) month period. This paper will present the test results of those tests.

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Outfall StudyThe 5-mile outfall is inspected externally on a yearly basis, but was never inspected internally during its 50-year existence. To collect sufficient information to establish and evaluate the condition of the pipeline, the City of Los Angeles in conjunction with Parsons Corporation initiated a program to conduct field studies for evaluation of the outfall in mid 2007. Divers were sent into the outfall to assess its structural condition, evaluate its reliability, and identify potential trouble spots. The inspection consisted of several scientific and engineering exams, including internal inspection, external remote operated vehicle inspection with sonar, field studies, hydraulic analyses, pressure evaluations, geotechnical investigations, seismic hazard, and structural stability analysis that utilized a physical model designed and constructed at the Oregon State University.Concrete core samples were also taken from the outfall to determine concrete strength and rebar condition. Inspection ResultsThe inspection revealed that the outfall itself was structurally sound. The strength of the concrete had not deteriorated and the rebar was intact. In addition, the pipe joints were not leaking and did not indicate signs of wear. However, the inspection did reveal that the ballasting in several locations had either washed away or settled into the seabed floor. It was recommended that a project be initiated to reballast the outfall to ensure protection and continued successful operation. Proposed ProjectThis project will apply approximately 40,000 cubic yards of additional 8, 10, and 12-inch minus rock ballast from Stations 92+00 to 275+25 up to pipe's mid point. The ballast will consist of a four foot table with a 1 to 1.5 slope from that point to the sea floor ( Figure 3). This project consists of a 3758 WEFTEC 2011

Hyperion Treatment Plant, with an average design flow capacity of 1,700 mld (450 mgd), is the largest of four treatment plants owned and operated by the City of Los Angeles. Recently, the plant implemented a 76,000 l/d (20,000 gal/d) pilot facility to investigate the benefits of adding FOG to its anaerobic digesters. The results were promising showing significant improvements in digester gas production. Therefore, a study was conducted to research FOG and food waste market and evaluate digesters capacity to receive such high strength wastes. The study concluded that FOG volumes as high as 380,000 l/d (100,000 gal/d) would be available to the plant. The City of Los Angeles, however, decided to initially expand the facility by 190,000 l/d (50,000 gal/d). This paper describes the alternatives considered for expanding the facility. Pros and cons of each alternative along with corresponding costs are presented. Finally, recommendations for expansion of the facility are provided.