PALMDALE — The Palmdale Water District Board of Directors gave the go-ahead to explore an alternative option for a water recharge project in the Big Rock Creek area, during its meeting, Monday night.
The Antelope Valley State Water Contractors Association, of which the District is a part, has been studying the feasibility of using surplus State Water Project water from the California Aqueduct to recharge the local aquifer by releasing it into the streamed of Big Rock Creek, southeast of Palmdale.
A pilot study of the original plan conducted in 2019-2020 proved to be infeasible, as the ground did not absorb the water fast enough to prevent it from spilling downstream, where it crossed and flooded Avenue T.
“Unfortunately, we did not get the results we wanted,” said Paul Chau of consulting firm Kennedy Jenks.
The association, with consultant Kennedy Jenks, came up with four alternative options for the project for potential further study.
Each alternative had trade-offs in terms of recharge capacity, environmental permitting requirements and costs.
The first option is to make berms within the Big Rock Creek stream bed to contain the water while it slowly percolates into the underlying aquifer. This option has the advantage of creating the full 20,000 acre-feet per year capacity for recharge, as well as low costs, about $500,000 initially to build and about $`1.65 million operations and maintenance costs over 20 years, Chau said.
However, it would require extensive environmental studies and permitting, taking up to two years to complete initially, then continuous environmental surveying as the berms need to be reconstructed with washouts due to storm runoff, according to Chau.
A second option would be to build culverts to transport the water under Avenue T and Avenue S to avoid flooding these roads.
This option has fewer costs than the first, with only $40,000 in operations and maintenance costs over 20 years and about the same costs to build, but reduced capacity of 2,200 acre-feet per year. This means the cost per acre-foot of recharge comes to $12, as opposed to $1 for the first option.
An acre-foot is 325,851 gallons, or approximately the amount of water occupants of a typical Antelope Valley single-family home used in one year, before the most recent drought reduced usage.
The third option is to create an off-site recharge basin north of East Avenue W-4, with pipelines bringing the water from the aqueduct. This would offer the desired recharge capacity of 20,000 acre-feet per year, but it come with high costs: nearly $10 million to build and just over $1 million in operations and maintenance costs over 20 years. With the high recharge capacity, it would amount to $24 per acre-foot.
However, as part of studying this option further, other locations closer to the turnout where water will be taken from the aqueduct will be examined. This optimization could reduce costs by reducing the amount of pipeline required.
“Pipeline cost is a big part of this,” Chau said.
It would also have limited permitting requirements.
This is the recommended option, and the one the PWD Directors endorsed.
The AVSWCA Commissioners decided to pursue this option at their Aug. 12 meeting. Each of the member organizations was asked to seek approval from their own governing boards, as well, prior to moving forward with further study.
The fourth option, which was discarded as being too costly and having too little recharge capacity, would be to use a booster station at the Antelope Valley-East Kern Water Agency’s wastewater treatment plant to pump the water through pipes to the north side of East Avenue T to a recharge area.
This option would cost just over $10 million to build and $1.38 million to operate and maintain over 20 years, for 2,200 acre-feet per year of recharge. This amounts to $192 per acre-foot.
It would also mean acquiring large amounts of easement to build, Chau said.
The four options were ranked, weighing the factors of recharge capacity and regulatory and permitting costs more heavily, to come up with a scale showing which option was optimal. This scoring had the third option, of an off-site recharge basin and pipeline, to be the best, Chau said.
With the approval of the AVSWCA entities, the next step in the process will be to identify possible sites for a recharge basin and optimize the design, then the required environmental studies.