The proposed Monterey Peninsula Groundwater Replenishment for the Monterey Peninsula Water Supply Project is to be modeled after the highly successful Orange County Groundwater Replenishment System (GwRS) which has safely provide purified water for 35 years.

Modeling Success in Orange County, California:

Orange County, California: Groundwater Replenishment System
The largest, most widely recognized and highly regarded water purification program in the water industry worldwide is a joint project of the Orange County Water District (OCWD) and Orange County Sanitation District (OCSD).

This project was the first in California to purify wastewater to drinking water standards as a barrier against intrusion seawater into a groundwater basin. Since 1976, the Groundwater Replenishment System (GWRS) has been protecting the integrity of the large groundwater basin that serves north and central Orange County, while also helping to increase the reliability of the area’s water supply.

Currently producing up to 70 million gallons of new purified water a day, the GWRS has just been approved to expand its system to create 100 million gallons per day, or an additional 31,000 acre feet per year (a total of 72,000 AFY) of new water supplies. Scheduled to be completed in September 2014, the total production of the newly expanded project will produce enough water for 850,000 people.

The GWRS provides a drought-proof water source for north and central Orange County, reducing reliance on imported water, reducing the amount of wastewater discharged to the Pacific Ocean, and prevents seawater intrusion into the groundwater basin. The new water produced by the GWRS requires just one-half the energy currently required to import water to the Orange County region. Additionally, the GWRS will save additional funds in the future by improving the quality of the water in the Orange County groundwater basin. This water quality improvement takes place when the new purified water, which is low in minerals, mixes with existing groundwater, lowering the average mineral content of Orange County’s water. Lowering the amount of minerals in the water, thus reducing water hardness, will decrease maintenance costs for Orange County’s residents and businesses by extending the life of water heaters, boilers, cooling towers and plumbing fixtures.

State-of-the-Art Technology

The project takes highly treated wastewater and purifies it to beyond drinking water standards using a three-step process that includes microfiltration, reverse osmosis, and oxidation with ultraviolet light with hydrogen peroxide. Once purified, the water is sent to recharge facilities or injection wells. The newly purified water is injected into the groundwater basin and blended with existing groundwater supplies.

Recharge Program

The Orange County Water District is responsible for managing the underground water reserves that supply about 500 wells within district boundaries. At the present time about 270,000 acre feet of this water is pumped for use each year. That quantity grows steadily, and projections indicate the demand may reach 450,000 acre feet a year in the next quarter century. (One acre foot of water, which would cover a football field to a depth of twelve inches, provides enough water for four average families for a full year.)

Groundwater reserves are maintained by an aquifer recharge system, which replaces water that is pumped from wells. Along a six-mile section of the Santa Ana River that belongs to OCWD, a system of diversion structures and recharge basins captures most of the water that would otherwise flow into the Pacific Ocean. The District has 1,500 acres of land for use in its recharge program.

Water that flows down the Santa Ana River, together with supplies imported from the Colorado River and from the State Water Project is channeled into nine recharge basins. These lakes and ponds, with depths ranging from 50 to 150 feet, were formed in years past by sand and gravel mining operations.

Additional Groundwater Replenishment Projects

West Basin Water District, California. Online since 1995, the district uses microfiltration, reverse osmosis and ultraviolet light technologies to treat recycled water for groundwater injection.

Los Angeles County, California. The Water Replenishment District of Southern California has managed the Montebello Forebay Groundwater Recharge Project since 1962. It is one of the oldest ongoing natural groundwater recharge sewer projects in the nation.

The Montebello Project filters an average of 45 million gallons per day of treated sewer water through the ground into the Los Angeles Central Groundwater Basin. The reclaimed water constitutes an average of 18.7 percent of the groundwater supply.

Sanitation Districts of Los Angeles County. The Sanitation Districts of Los Angeles County utilize recycled water from three of their wastewater treatment plants for groundwater recharge.

San Bernardino County, California. Recycled water from one of the Inland Empire Utilities Agency’s (IEUA) treatment plants is currently used to recharge the Chino Basin aquifer at the rate of 500 acre-feet per year and is scheduled to increase to 2,300 acre-feet per year in the future.

Reno, Nevada. The Tahoe-Truckee Sanitation Agency Water Reclamation Plant combines conventional activated sludge secondary treatment with biological phosphorus removal to treat the wastewater. The treated water is released into the Truckee River, which is the source of the City of Reno’s water supply.

Las Vegas, Nevada. Since the 1950s, secondary treated wastewater has been discharged into the Las Vegas Wash and represents two percent of the flow into Lake Mead, tthe primary drinking water source for the Las Vegas Valley.

El Paso, Texas. The Fred Hervey Water Reclamation Plant recovers and treats wastewater, which is then injected into groundwater. The water eventually travels to one of El Paso’s potable water fields to become part of the drinking water supply. In 2004, a total of 577 million gallons of reclaimed water were returned to the Hueco Bolson aquifer.

Scottsdale, Arizona. Since 1998, the Scottsdale Water Campus has produced 12 million gallons per day of tertiary treated wastewater that is used primarily for use on parks, medians and golf courses. In winter, when irrigation is reduced, 10 million gallons per day undergo advanced purification to meet or surpass drinking water standards before the water is used to recharge groundwater sources.

City of Peoria, Arizona. The city currently recharges 2,000 acre-feet of water per year from their Beardsley Water Reclamation Facility.

City of Glendale, Arizona. Reclaimed water is being used directly on landscaping and being stored in the aquifer.

Fairfax, Virginia: Upper Occoquan Sewage Authority (UOSA), Millard H. Robbins, Jr. Water Reclamation Plant. Since UOSA came on-line in 1978 to replace 11 secondary wastewater treatment plants that were decommissioned, the quality of water in the Occoquan Reservoir has dramatically improved and is generally much higher than that of the receiving stream.

NEWater Facilities, Singapore. The latest ultrafiltration/microfiltration and reverse osmosis membrane technologies, followed by ultraviolet disinfection, treat used water to standards higher than the drinking water standards of the World Health Organization and the U.S. Environmental Protection Agency. The project has been fully operational since 2003.

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