Capital Projects

Installation of New Aerators for the Oxidation Ditch – $156,100

The Oxidation Ditch is located at the front end of the plant where raw sewage enters the treatment plant system. The new aerators add air to the sewage and allow microorganisms in the ditch to treat the sewage by converting it to inorganic waste. The new aerators replaced an old style aerator which is no longer manufactured.


Rebuild and Replacement of the Secondary Clarifier Sweep Arms and Drives – $209,500

The treatment plant has three Clarifiers: a larger main clarifier, which is currently in use, and two smaller ones which serve as backup and redundancy to the main clarifier. The clarifiers are the next stop for the partially treated sewage coming from the Oxidation Basin, and serve to separate the sludge solids from the effluent water. These units were upgraded due to aging parts and the harsh environment the mechanical parts are subject to.


New Aerobic Digester Blower Motors – $140,200

The Aerobic Digester tanks are located at the back end of the treatment plant process. The digester takes the solids that are pumped from the Clarifier, thickens it, and then sends that sludge to the Centrifuge for further drying. The new Blower motors are an upgrade from the previous mechanical mixers and aeration system, which were prone to failure due to the harsh sewage environment they were located in. The new blowers sit on top of the digester building and pipe the air down into the tanks.

Centrifuge upgrade to the mechanicals, control panel, and feed pumps – $168,000

The Centrifuge Unit is the last stop for the treatment of sewage solids before they are conveyed into a bin and leave the plant. Since the cost for hauling sludge is largely weight based, the purpose of the centrifuge is to spin at a high rate of speed to further separate the solids from the effluent in the sewage, akin to the spin cycle in a washing machine. This project first overhauled the mechanical parts of the centrifuge itself, essentially rebuilding the machine. Part two of the project upgraded the control panel and chemical feed pumps to the centrifuge, which had become obsolete due to age.


Odor Control System Upgrade – $157,400

The Odor Control System consists of a series of ducts from the plant headworks at the front end of the plant and the solids handling building at the back end of the plant. The system works by drawing air from these two buildings through the ducts and filtering it through the odor control tanks shown below. A mix of sodium hypochlorite and sodium hydroxide is pumped through the individual tanks to treat the sulfide gas produced by the sewage and sludge at the plant. The Odor Control System was a part of the 1994 plant upgrade, and the new feed pumps, system interface, and odor control media serve as replacements and upgrades from the original, while also providing redundancy for the system.


Upgrade of Effluent Pumping System – $83,200

The in-plant concrete lined pond pictured below serves as a forebay for the effluent disposal system. After sewage is biologically treated in the Oxidation Ditch, solids and liquid effluent are separated in the clarifier. The liquid effluent then flows to the pond and subsequently pumped over the ridgeline north of the treatment plant. There it flows into the District’s percolation ponds located off Via De Santa, adjacent to the equestrian farms. This project improves the reliability of the effluent pump system.


Portable Emergency Pump – $76,800

The Godwin Portable pump is used in events where there is a power outage, or when a pump station or part of the treatment process needs to be bypassed to allow repairs to be completed. This is a new piece of equipment.


Generator Replacement – $56,100

The Diesel Generator is used as a power backup in the event of a power disruption or outage. The original generator at the treatment plant had been in service for over 30 years. When it finally broke down, it could not be repaired in a cost effective manner and did not meet current air quality regulations. The new generator is categorized as a Tier 3 engine and meets the more stringent regulatory requirements.