Water Management at Twentynine Palms
Effective water resource management is key to reaching sustainability goals at Marine Corps Air Ground Combat Center Twentynine Palms in the Mojave Desert.
By Chris Elliot and John C. Matthews, PH.D., M.SAME
The U.S. Marine Corps issued an order in 2010 to enact a Sustainability Management Program to provide policies that support the goals of Executive Order 13514, Executive Order 13423, and the 2011 Department of Defense Strategic Sustainability Performance Plan. The program requires Marine Corps installations to develop and implement an Installation Sustainability Action Plan.
Marine Corps Air Ground Combat Center (MCAGCC) Twentynine Palms, Calif., used 766-million-gal of potable water in CY2012. Given this high demand, a key focus of the base’s Installation Sustainability Action Plan is water resource management. Both EO 13423 and EO 13514 include quantifiable water-related goals for reductions in potable water consumption (26 percent reduction by FY2020 relative to the FY2007 baseline) and non-potable water consumption (a 20 percent reduction by FY2020 relative to an FY2010 baseline).
For MCAGCC, meeting these water-related goals is a demanding pursuit given the base’s location in the Mojave Desert.
MCAGCC’s potable water demands are provided by groundwater wells that provide up to 3-million-gal per day. These wells are located in the Surprise Spring aquifer, where the quality of the groundwater meets the requirements for potable use with minimal treatment.
Studies of the aquifer estimate the recharge to be approximately 0.9-million-gal per day. Therefore, approximately three times more water (3-million-gal per day) is being extracted than is being replenished. This creates concerns that drawdown will result in decreased water quality requiring additional treatment. Since the 1950s, aquifer levels have decreased nearly 200-ft.
MCAGCC has undertaken efforts to reduce drawdown in support of water sustainability and mission longevity. These actions include:
- converting green space areas to xeriscape and installing Astroturf, reducing potable water demand for irrigation;
- installing non-potable wells to support construction, diverting the usage of potable water for construction;
- developing long range management tools (an Urban Water Management Plan); and
- increasing recycled water use from 32 percent to 52 percent in one year.
POTABLE WATER USE
Most of the distribution system has been replaced in the last 10 years and is in good condition. But to improve the understanding of water allocation within the distribution system, MCAGCC is developing a water meter survey/study to establish optimum locations for additional metering and data collection points.
Irrigation demand has been decreased, for instance, by converting some green areas to xeriscape areas. Eliminating using potable water for irrigation also would provide an immediate payback of as much as 1.7-million-gal per day. The installation’s goal is to make up the 1.7-million-gal per day with as much recycled water as possible.
NON-POTABLE WATER USE
Historically, three non-potable wells have provided water to meet/augment demands at a golf course, vehicle washing station, and urban terrain training area. The majority of non-potable water is used for golf course irrigation, where the well water is combined with recycled water from the Wastewater Treatment Plant in a holding pond. Recently, two more wells were installed to support construction and produced about 0.19-million-gal per day.
Non-potable water consumption increased by 230 percent from FY2010 to FY2011, primarily due to the additional wells supporting construction activities—with the remaining increase due to variable production of recycled water used for golf course irrigation.
RECYCLED WATER USE
Recycled water is limited to irrigation at the golf course, where it is combined with non-potable water at the holding pond. MCAGCC has the required infrastructure and permits to distribute recycled water to support other irrigation areas—but the Wastewater Treatment Plant does not produce enough to supply the golf course and other areas as more than 50 percent of wastewater is estimated to be lost to evaporation. MCAGCC has increased the use of recycled water from 116-million-gal per day (or 32 percent) to 156-million-gal per day (or 52 percent).
To improve the reuse of wastewater, MCAGCC is studying wastewater treatment options that provide the best fit for water conservation, meet regulatory requirements, and supports the Marine Corps mission. MCAGCC continues working to balance water load between recycled water and non-potable water to reduce the use of potable water for non-potable uses.
MCAGCC has made tremendous strides toward achieving potable water reduction goals. However, it is beneficial for the long-term sustainability of water resources and water security that continued efforts be made to minimize demand on the aquifer. Meeting non-potable water goals will prove challenging, though, since the non-potable irrigation system will likely increase unless recycled water use can be increased. As potable water use has continually decreased and recycled water use is increasing, non-potable water use has substantially increased as well. There is a need to optimize recycled water use to offset potable water usage as well as non-potable usage.
MCAGCC is taking actions to optimize the Waste Water Treatment Plant to treat and recycle 100 percent of the wastewater since recycled water does not contribute to consumption calculations for non-potable water. Once the treatment plant is optimized, the infrastructure and permitting is in place to transport recycled water up to 1-million-gal per day to offset potable water use for irrigation.
Some recycled water is lost in both the wastewater treatment process and golf course holding ponds due to evaporation. While the 0.28-million-gal per day over-demand pumped into the golf course holding ponds may not all be attributable to evaporation, measures can be taken to minimize evaporation and other losses to ensure maximum use of non-potable and recycled water resources.
These measures could include eliminating the use of the large holding pond and continuing to use the smaller one and applying a floating cover, which would eliminate evaporation losses from that pond. Other potential actions include:
- increasing efficiency of the potable system using a strategic leak detection program, formalized protocols for installing water efficient fixtures, and additional flow meters to make informed decisions on water efficiency and conservation;
- reducing potable source water usage to meet non-potable demand by implementing infrastructure and water storage improvements that will ensure the maximum amount of non-potable or recycled water is available to meet demand and prevent loss due to evaporation;
- maximizing recycled water use to meet non-potable demand achieved by implementing measures to minimize the loss of wastewater and increased efficiency of the Waste Water Treatment Plant so that treated effluent quality meets use requirements; and
- decreasing potable and non-potable demand by fostering responsible water use practices—achieved through media products that cultivate an informed, responsible end user, and by an enforcement program to communicate responsible irrigation practices to base personnel.
MCAGCC at Twentynine Palms has implemented a program to meet the requirements of recent federal guidelines and executive orders. Progress is being tracked and improvement is being made, though work must continue to guarantee the long-term sustainability of its water resources and water security.