Treatment Requirements - Wastewater discharges at Rancho Murieta are controlled by the California Regional Water Quality Control Board, Central Valley Region. Because of the pristine nature of the Cosumnes River, a discharge to the river is not allowed, thus, other disposal or reuse options were pursued. 

Reuse of the treated wastewater on the two golf courses was selected. Reclaimed water used for the irrigation of parks, playgrounds, schoolyards, and the golf course, must meet the requirements of Title 22, Division 4 of the California Code which require an adequately oxidized, coagulated, clarified, filtered, and disinfected wastewater.

Treatment Process Overview - Because a substantial amount of land was available within the development, a system utilizing a series of aerobic/anaerobic ponds was selected. This type of system provides the required treatment at a low operating cost to the District. The ponds are followed by a tertiary treatment process, which meets the more extensive reuse standards of Title 22.

The treatment process utilized at Rancho Murieta is unique in that it utilizes a number of basic and proven processes to produce a very high quality effluent. To date, the process train used at Rancho Murieta is the only one in the State of California.

Wastewater is received at the treatment plant from three major pumping stations and flows successively through the other five ponds. Wastewater is treated in the ponds naturally through bacteriological action supplemented with mechanical aeration. The pond effluent is stored in two large reservoirs. Within these reservoirs additional natural treatment occurs. These reservoirs allow storage of the secondary treated wastewater until the need arises for irrigation of the golf course. When this occurs, generally in late April, stored secondary effluent is further treated in the tertiary plant. It is operated until the supply from the reservoirs is exhausted or the irrigation season ends, about the middle of October.

The tertiary plant utilizes the Dissolved Air Floatation process, followed by filtration. These processes remove algae and fine solids contained in the secondary effluent. The effluent from the filter is discharged to the chlorination contact chamber for disinfection.

Disinfected wastewater enters an equalization basin. It serves as a flow equalizer, as the demand from the golf course varies throughout the day, while it is most desirable to maintain a fixed flow through the tertiary process.

Aeration Ponds - A total of five ponds are constructed and operated in series. They have a depth of nine feet. Floating aerators are used to assure that sufficient oxygen is provided at all times to supplement the natural treatment.

Storage Reservoirs - Two large reservoirs are provided to retain the secondary effluent during the rainy season. They have a combined area of almost 22 acres, (756 acre-feet) resulting in the detention time of about 155 days.

Dissolved Air Floatation (DAF) - The DAF removes algae and suspended solids. As the wastewater enters the DAF tank, fine air bubbles carry the algae to the surface, where it is removed with a skimmer. The DAF is capable of removing sufficient algae to nearly meet the turbidity standards most of the time without the need for subsequent filtration. Filtration provides an insurance to meet the high discharge quality standards.

Disinfection - Title 22 requires that reclaimed wastewater must be disinfected and remain in contact with chlorine for a minimum detention time of 120 minutes. The contact chamber is baffled to ensure the contact time is met.

Equalization Basin - Reclaimed water is stored until needed and then it is pumped from the equalizer basin to the golf course irrigation ponds. The equalization basin has a capacity of over 1 million gallons.

Reuse - Reuse of the effluent is on the two golf courses. They have a combined irrigation of 238 acres and have a peak demand of about 3 MGD during the summer months. The tertiary treatment plant operates from late April through October.