By Don A. Wright
A company named Parjana Engineering, Inc. has developed a system that increases groundwater recharge within a defined area such as a basin, as demonstrated in this study. The technology shows strong potential to expand recharge capacity at a time when the Sustainable Groundwater Management Act is reshaping how California manages its aquifers.
I first learned about Parjana Engineering, Inc. approximately thirteen years ago at a water forum in Clovis. Many of our readers will also be familiar with their work.
Due to SGMA, the San Joaquin Valley is facing the potential retirement of more than one million acres of irrigated farmland, according to some estimates. This challenge is driven largely by a shortage of contracted surface water deliveries. Recharge requires surface water, and during spring and summer snowmelt events California often receives significant volumes of runoff, even in dry years. The challenge is maximizing the volume of this water that can be moved underground.
In an average year, the San Joaquin Valley operates with an annual groundwater deficit of approximately two-million-acre feet, while more than ten-million-acre feet of freshwater flows from the Delta to the Golden Gate and ultimately out to sea. The water exists for recharge if it can be conveyed or captured at the right locations. It has been difficult to move the volumes needed from north of the Delta through the state and federal conveyance systems to the south. As a result, locally generated flows south of the Delta must be recharged as efficiently as possible.
Leaky Acres is a groundwater recharge facility in Fresno, California that captures and infiltrates stormwater into the regional aquifer. Within this larger complex, the basin known as Silt Bay 6, or SB6, was originally designed as a siltation unit to slow incoming stormwater and allow sediment to settle before the water reached nearby infiltration basins. Over time, SB6 accumulated organic material and suspended solids that reduced infiltration efficiency and required recurring scraping to maintain performance.
To improve the function of SB6, the City contracted Parjana Engineering, Inc. and The Water Group LLC to retrofit the basin with a system designed to enhance infiltration and restore long term recharge capacity.
- Water Savings Before installation, as much as 70 percent of the water entering Silt Bay 6 was lost to evaporation. With accelerated infiltration in place, losses dropped to only 14 percent. This improvement prevented up to 35,000 gallons per day from evaporating during peak summer months.
- Reduced Maintenance Requirements Historically, Silt Bay 6 required biannual scraping to remove accumulated silt. After installation, only light surface inspections and occasional backfilling of drill divots, approximately 14 percent of drilled points, were needed. This confirmed stable long-term performance with no clogging or sediment driven decline.
- All Season Performance The system maintained consistent infiltration throughout the year, supporting recharge even during dry periods or periods of variable stormwater flow.
For more information about the Parjana Engineering, Inc. recharge system and to access the full study, click here.
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