As many other cities around the country, the City of Raymore designed their force mains for future growth. The Owen Good Pump Station has a capacity of over 7 MGD, but pumps less than 1 MGD, resulting in less than optimum velocities in the force main and hydraulic retention times of up to 17 hours. Sewage goes septic after approx. 1 hour in a force main, at which point the sulﬁde formation begins. City staff measured H2S concentrations of 123 ppm avg. with daily spikes of up to 600-900 ppm at the discharge of the over 3 mile long 24’’ force main.
The City realized that these H2S concentrations go beyond the odor complaints they’ve been receiving in the downtown area and the accelerated corrosion they’ve been experiencing. The data indicates that at times the City staff maybe exposed to a severe health risk when working in their gravity system.
The consultant prepared an odor evaluation for the City of Raymore, comparing the ECO2 Technology to two other oxygen injection methods, as well as traditional chemical feed alternatives, such as calcium nitrate, Bioxide®, ferrous chloride, hydrogen peroxide, potassium permanganate and sodium hypochlorite.