Water plant still compliant 10 years after initial packaged filter plant installation
Located in Ventura County, Calif., and nestled at the western end of the beautiful Ojai Valley, Meiners Oaks County Water District has served the community since 1949.
A small but capable water district, Meiners Oaks prides itself on the service it provides to its customers. When the district was faced with installing a filter plant in a remote location they began to look for the best performing, most affordable filtration system available.
The Safe Drinking Water Act and the resulting water regulations that govern surface water and ground water sources in the U.S. require filtration of those source waters prior to use as drinking water. These are the regulations the Meiners Oaks Water District was faced with in 1993 that made them begin their search for filtration systems even though no regulated contaminants were found in the source water at the time.
The Water District researched the many choices of filtration technologies available and eventually sent requests for proposals to six different manufacturers.
Wanting to include the latest technologies and treatment techniques in the quest, the district reviewed everything from conventional treatment plants to membrane technologies.
The district’s criteria were basic: supply a packaged filter plant that meets the requirements of the Surface Water Treatment Rule; gain approval on that plant by the California Department of Health Services which regulates water systems in the area; have a flow range of 360–800 GPM; meet the Uniform Building Code Seismic Zone 4 requirements; and have a final cost that fit within the district’s budget.
Testing and results
In February 1994, after extensive review, the district approved the proposal of the EPD Wearnes, Inc., for their package filtration plant technology.
Before installation of the full scale package plant, a pilot study was to be undertaken by EPD to prove the efficacy of the system—this took place in the first two weeks of April 1994.
Due to the pristine nature of the wells at Meiners Oaks, the most difficult task in the study was to achieve particle removal from a remarkably clean source. This was done by adding or “spiking” the influent water with particulate matter of a known size range in order to count the results with the pilot system’s on board laser particle counters.
After two weeks of testing the data was reviewed, compiled and presented to the state for approval. The tests revealed outstanding performance by the system under a variety of conditions, which included, varying flow rates and high turbidities.
- 98% reduction in turbidity on spiked samples, 3.3 times lower than required;
- 3.91-log removal of Cryptosporidium sized particles with coagulation; and
- 3.96-log removal of Giardia sized particles with coagulation.
Testing also proved the system’s quick recovery after backwashing, which leads to overall production efficiency, low coagulant consumption for economy and ease of operation for less supervision and labor.
The Meiners Oaks Plant currently operates 24 hours a day and has done so since startup in 1995. The plant has never been out of compliance with health department standards and has ceased full production capacity only for short periods of time for repairs.
Maintenance and operation costs on average are $1,000 a year, with the majority of that cost being the purchase of chemicals and the remainder being labor at 20-30 minutes a day for record keeping.
After nine years of continuous operation, the Meiners Oaks County Water District confidently boasts that the purchase of the packaged filter plant is one of the best purchases it has ever made.