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growth is avoided(and the potential for odors from that source) The shallow water depth allows aerobic conditions to prevail by natural reaeration. As stressed in the above descriptions the goal of avoiding odors is to avoid persistent anaerobic conditions. The Lathrop plant avoids this problem by having a very reliable Dissolved Oxygen Control system which carefully regulates the amount of oxygen present and which alarms conditions that are not up to specification. In addition to making the process proceed correctly it is also a way of gaining a considerable energy savings , since energy is not wasted compressing more air then is needed. The processes used at Lathrop include: o Influent bar screens - to remove large objects,plastics,rocks, etc. o Aerated Grit & Grease Removal - to remove small rocks , sand,coffee grounds ,egg shells,grease, and floating oils. o Extended Aeration Activated Sludge - the main treatment process to aerobically stabilize the wastewater and which is also used to nitrify and de-nitrify the waste stream. o Sedimentation and sludge recycle - separates the sludge from the mixture and returns it to the process. The clarified water continues to disinfection. o Disinfection - chlorine solution is added to kill residual bacteria. o Waste Sludge - excess sludge is dewatered by adding polymer to the fresh sludge and then rapidly dewatering it, and in this way keeping it aerobic at all times. o Percolation - percolation into the ground in one or more percolation ponds. There are sufficient ponds to rotate the use of ponds so that the water is kept shallow, and aerobic at all times. The quality of the effluent will be significantly better then the "allowed" levels of 30 - 30 . Typical effluent value will be in the 10 to 15 mg/l range with the nitrogen being less then 5 mg/1( as compared to 25 to 40 for the other plants) Should there be anything in this description of the processes which is not clear, or if there is anything else which would be helpful please do not hesitate to contact me. Yours Trul William Strangio D.Sc. , P.E.