Planning and Implementing Odor Control During Sewer System Inspection, and Rehabilitation Work in a Senstive Resort Setting in Orange County, California – Case Study

Orange County Sanitation District (OCSD) is a large wastewater collection and treatment organization headquartered in Fountain Valley, California. OCSD operates the third largest wastewater agency west of the Mississippi River. For over 50 years, the District has collected, treated disposed of, or reclaimed wastewater generated by 2.5 million people living and working in central and northwestern Orange County, California.Approximately 250 million gallons of wastewater is treated each day at Plant No. 1, located in Fountain Valley and Plant No. 2, located in Huntington Beach. Approximately 80 percent of the wastewater comes from residences. The remainder comes from businesses such as retail stores, restaurants, manufacturing, hotels, offices, and other industries.Both treatment facilities are located adjacent to residential neighborhoods that required effective odor containment, collection, and treatment to meet the neighborhood expectation of “no odors”. In this location the expectation of “no odors” extends far out into the reaches of the collection system. The expectation of “no odors” is extended to short term temporary work such as sewer inspection, cleaning and rehabilitation activities. The regulations for “no odors” originate with the South Coast Air Quality Management District (SCAQMD) and strict enforcement requirements are in effect at all times in the area. OCSD must rigorously manage their operations in all areas (wastewater collection, conveyance and treatment) because even a single citizen complaint can cause an enforcement action to be levied by SCAQMD.During 2009 AECOM began work on the inspection and design of repairs to the OCSD Balboa Trunk Sewer that traverses the Balboa Peninsula in the City of Newport Beach. The Balboa Trunk Sewer is located in heavily travelled streets and is surrounded by upscale residential housing, retail establishments, restaurants, and boating. During the summer traffic can extend into the early morning hours, so scheduling work during off hours where minimal public activities are occurring is not feasible. During the planning and design of the odor mitigation program four (4) sampling and monitoring stations were set up to track odors in the headspace of the sewer, and along the street surface. At the upstream end of the Balboa Trunk Sewer the headspace hydrogen sulfide (H2S) concentrations ranged from 0.0 to 73.0 parts per million by volume (ppmv) with an average of 6.0 ppmv. At the mid-point sampling locations the headspace H2S concentrations ranged from 0.0 to 41.0 ppmv with an average of 6.0 ppmv. At the downstream end of the Balboa Trunk Sewer the headspace H2S concentrations ranged from 0.0 to 259.0 ppmv with an average of 16.0 ppmv.This paper will present initial odor monitoring results that were used to plan and design odor mitigation techniques that will be put into place during the required sewer inspections, cleaning, and rehabilitation work. The odor monitoring data is used to design the chemical feed system that is being used during the sewer inspection, cleaning, and rehabilitation activities that are presently underway. This paper will also present odor monitoring data that is continuously recorded at the street surface at all times during the work activities.