Water Well Journal
Issue link: https://read.dmtmag.com/i/681918
In the southern area of the San Joaquin Valley near Bakers- field, deep groundwater (more than than 500 feet) is older and can have high levels of arsenic, says Tom Harder, owner of Thomas Harder & Co. Groundwater Consulting in Anaheim, California. This can present a water quality issue for some of the water banking agencies along the Kern River, according to Harder, particularly during periods when groundwater levels are low, as they are now. Wells used to pump stored water during dry times are typically perforated in both the shallow and deep aquifers. As the groundwater level drops in the shallow aquifer due to pumping, the source of water to the wells is in- creasingly from the deep aquifer and the arsenic concentration in the pumped water tends to increase. Agency water is discharged to area canals and the arsenic concentration can't exceed the maximum contaminant level, which is 10 micrograms per liter. While the water from some individual wells has exceeded the maximum contaminant level, agencies have been able to blend the well water sources to keep the arsenic within acceptable limits. However, further lowering of the groundwater level may limit their ability to do this. Water Level Water year 2014 closed as the third driest year since records began in the city of Turlock. In the same year, the city's 23 active wells pumped a total of 6.6 billion gallons of drinking water (down from 7.4 billion in 2013). Through its water conservation program, the city's resi- dents have significantly reduced their water consumption (decreased 13.3% from 2013 to 2014). But due to the drought and other effects within the subbasin, groundwater levels are continuing to decline, according to the city's water quality annual report. The 2015 report was in the process of being completed at press time. The California Department of Water Resources estimated spring groundwater levels in 52% of the long-term wells (1934 of 3723) in the Central Valley are at or below the histor- ical spring low levels in 2015. These water-level declines are noticeably evident in the southern two-thirds of the Central Valley known as the San Joaquin Valley, where water-level declines have been connected to land subsidence (more on that later). The USGS reported the Central Valley has many areas where groundwater levels are more than 100 feet below previous historical lows. Water-level declines are having a far-reaching impact beyond the wellhead. For farmers, it takes more energy, thus more money, to pump less groundwater. Making matters worse is the shift away from row crops to essentially perennials needing year- round watering. Tree nut farming has also become more common as of late—particularly for almonds, and creating conversation in the San Joaquin Valley. Almonds are a lucra- tive crop and need watered year-round. For water well contractors, it is costing them more time and money to drill these deeper wells. The increase in time constructing a well has been felt by Arthur & Orum Well Drilling, where what used to take a cou- ple of days is now a week to 10 days depending on the forma- tion for a well averaging 900 to 1000 feet. The deepest wells are in the 1200 to 2000 feet range. In past years the average depth of a well was 600 to 800 feet. Most of the drilling Arthur & Orum does is either reverse rotary or mud rotary, with air drilling used when closer to the mountains. Drilling through clay types can be quite gooey, akin to a bucket of grease, Steve says. Therefore, a good mud program with the appropriate mud types, mud additives, and increased mud density is required to prevent problems whenever using reverse or mud drilling. "You have to mud up ahead of time and know the areas where to put in the right chemical or the formation you're going to get," he says. "With the sticky clays and swelling clays, we run a pack in there to keep it from swelling and it makes a big difference if you prep that hole." Steve, whose company has not drilled in the Turlock Sub- basin in recent years, says many drillers don't use mud when drilling to save on costs. He warns they risk having washouts. Another reason to use mud is if shale is present. If shale be- comes wet, it will begin to crumble off in the hole. A good mud program helps to seal that off. Safety, the issue focus of this month's Water Well Journal, isn't taken lightly by Steve. He tries to get out to the various drill sites at least every other day and scans job sites for proper personal protective equipment being used by his em- ployees. "I tell guys if you see something you're not comfortable with, I'll make a special trip and get the problem solved," says 56-year-old Steve. "If we have a bad cable, I'll get a new cable before we go any further. You're only as good as the people you work with." The water-level declines in the Central Valley have gar- nered local and national media attention in recent years. Steve has been interviewed more times than he can remember and spoken with the likes of 60 Minutes, National Geographic Channel, and HBO. Concern over the state's groundwater supply pushed Cali- fornia to pass the landmark Sustainable Groundwater Man- agement Act (SGMA), enacted by Governor Jerry Brown in September 2014. Prior to the passage, California lacked statewide regulation of groundwater pumping or standards for groundwater management. Arthur & Orum Well Drilling is family owned and operated. From left to right: Barbara Arthur, Steve Arthur, Kim Hammond (Steve's sister), Alyssa Lewis (Kim's daughter), and Floyd Arthur. Photos courtesy Arthur & Orum Well Drilling. TURLOCK AND SAN JOAQUIN continues on page 32 WWJ June 2016 31 Twitter @WaterWellJournl