A Day in the Life: Groundwater Sampling in Jurupa Valley

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Field work is a part of life many CAWSC scientists have grown accustomed to – being away from home, working long hours, often in extreme weather or under trying conditions, at urban and remote sites across California. All for the sake of science.

Today, Mike, David, and Josh are collecting samples from wells installed to monitor groundwater and flow in Jurupa Valley, a town in Riverside County. On any given day of the week, you can most likely find them or their colleagues at one of hundreds of water sampling sites throughout the State.

The team is collecting samples to study sources of perchlorate in Jurupa Valley's groundwater. According to the U.S. Environmental Protection Agency, perchlorate is "a naturally occurring and manufactured chemical anion" commonly used "in rocket propellants, munitions, fireworks, airbag initiators for vehicles, matches and signal flares," and is naturally occurring in some fertilizers. Measuring the presence of perchlorate in groundwater is important because the chemical can have adverse health effects on humans and wildlife.

The investigation of perchlorate is especially critical in areas like Jurupa Valley. The town is downgradient of the Stringfellow Superfund Site, a former chemical dumping site that was active between 1952 and 1973. The USGS and its cooperators in Jurupa Valley are working together to better understand the scope and sources of perchlorate contamination in the area. The USGS has been working on the Stringfellow project since 2014, after the Department of Toxic Substances Control determined there was a need for a comprehensive evaluation of the region’s groundwater quality.

"This project is important because it's going to provide scientific data and analysis to help legislators and mangers make informed decisions on management strategies at the Superfund Site," said Mike Wright, the project chief of the USGS-led study. "Interested parties need to come to a decision on what needs to be done to clean up the site, and they will use our data to better understand the potential sources of perchlorate in the groundwater."

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Mike, David, and Josh maneuver a large camper and a truck hauling a trailer loaded with specialized equipment to sample their first well of the day. The well is in a residential neighborhood, just off the side of the road on a corner lot. After parking and marking the street with traffic cones, they begin to unload the gear they’ll need for the day. Out of the hauled trailer they pull PVC pipes, toolboxes, measuring tapes, buckets, bottles, boxes of gloves. They immediately get to work prepping the site for sampling collection, setting up a large patio umbrella over the well to shield them, their gear, and their work from the harsh mid-morning sun.

Josh opens the cover to the well. An unassuming PVC pipe is sticking out, but this "well" is where the action takes place. The crew gets to work lowering a balloon-like piece of equipment called a "packer," into the well attached to the end of pipe. Typically, a packer is used to isolate and study different zones of groundwater flowing in an aquifer, but the USGS crew also uses it to guarantee the quality of the samples.

The crew lowers the packer into the well before inflating it at a predetermined depth, which varies by well. The packer presses up against the walls of the well as it inflates, preventing soil and atmospheric air from getting entrained in samples as groundwater levels decline during pumping. Once the packer is inflated and the water is isolated, the team can begin to purge stagnant water from the well in order to prepare the well for sampling. This stagnant well water may not be representative of the groundwater is in the aquifer. The team carefully monitors the water flowing from the well for water quality parameters like pH balance, electric conductivity, dissolved oxygen, and temperature. Josh closely watches these numbers, patiently waiting for them to stabilize so that a representative groundwater quality sample can be collected. This takes about an hour.

While Josh monitors the groundwater readings, David canvases the well, making detailed notations regarding the location, appearance, depth, and other defining features of the site. When the well is prepped and water is flowing, David dons a pair of gloves and prepares to fill a variety of vessels with water from the sampling well.

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As a USGS hydrologist, David is trained and practiced in the variety of techniques used to collect different types of water samples. He closely follows USGS protocol learned during an intensive Field Methods class, and practiced continually throughout his three years with the Survey. For David, the Stringfellow sampling resembles years of past field trips in many ways, except one: this time, he's the lead field hydrologist, responsible for ensuring that samples are collected, shipped, and processed, and also for accurately completing paperwork for all USGS’s samples collected for the project.

David uses a small tube to guide water into a bucket, where he gently submerges a glass bottle before sealing it with a rubber stopper. This particular sample will be used to test for dissolved gas concentrations, which offer insight into how the groundwater is recharged.

The final samples of the day are taken to find out the concentration of noble gases dissolved in the groundwater. For the Stringfellow project, the crews are testing for helium, xenon, krypton, neon, and argon. Noble gas sample collection involves capturing and storing groundwater in copper tubes attached to a metal backing plate. After the water flows into the tube, David uses a wrench to cinch down specially machined clamps on the ends of the tube, so that the tube will hold the water inside without letting in or out any gases, which would bias the sample results. These samples are not commonly collected during groundwater sampling, but Mike has his team collecting them in Jurupa Valley in order to have a more complete picture of the sources and nature of the groundwater here.

"Noble gases help tell the history of groundwater with respect to when and how it was recharged," Mike said. "This, in turn, will help indicate the various sources of perchlorate in the study area."

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After all of the samples are collected, sealed, and labeled, they must be shipped to USGS laboratories around the country for analysis. Time is of the essence for some of these samples, and many need to be packed in ice and shipped off to arrive at laboratories within 24 hours, while some can be stored for longer periods of time. Regardless of where the samples are sent, it is the field crews’ responsibility to get the samples to where they’re going and ensure it’s done properly. After passing a rigorous quality assurance review, all of this information will be entered into a publicly accessible, digital water database – the National Water Information System, or NWIS.

The crew returns to where they stage equipment at the Superfund Site to drop off their trailers full of gear before heading home for the night for a shower and a much-needed sleep before another long day in the field. Depending on the nature of the project and scheduled field work, home might be a different hotel and a different city every night for days, sometimes weeks. Other times, they make the long haul back to the USGS office in San Diego, with a stop for a well-deserved California burrito on the way.