Converting an Odor Control Plan to Corrosion Control

Manatee County, Florida has maintained an odor and corrosion control program for over 20 years. While the program was designed with the capability to control both odors and corrosion, the primary objective of the program has been control of odors, specifically odor complaints. Recently, the County investigated changing the objectives of the program from odor to corrosion control. The County’s goal for corrosion control is to protect and prolong the life of master lift stations, larger forcemains, and gravity interceptors. The objective is to reduce H2S levels to 2S levels into the corrosion control range of ≤ 10 ppm. The team then began to investigate the County’s master lift station’s service areas to pinpoint sulfide generation hotspots. Key elements in identifying sulfide generation hotspots included Manatee County’s available data on their collection system. A thorough investigation of the collection system was conducted resulting in recommendations for additional chemical feed locations. Due to challenges in the collection system, including availability of wastewater sampling locations, trials at expert chosen locations proved to be the best way to predict the success of a permanent chemical feed site for corrosion control. An effective corrosion control plan is made possible through a partnership with the utility, an odor and corrosion control supplier, and through the professional services of consulting engineers.Conclusions drawn are as follows:Liquid samples downstream of a lift station may not always be possible, which would be necessary to predict a chemical dose rate.Some collection systems may not be a good fit for corrosion control due to layout.Trial and error may be the only possible way to set a chemical dose rate for corrosion control.An Odor Control Plan cannot be directly converted into a Corrosion Control Plan through turning up dose rates at existing feed sites.