City Services

Feb 24

[ARCHIVED] Wastewater Lab

The original item was published from February 23, 2021 1:11 PM to February 25, 2021 1:29 PM

Testing and otherwise analyzing Roswell’s wastewater on a constant basis to make sure it is safe to be disposed of – and even used for farm irrigation – is the task of the Wastewater Laboratory at the City of Roswell’s Wastewater Treatment Plant on East College Boulevard at the city’s eastern edge.

The Wastewater Lab monitors the wastewater going through and leaving the treatment plant seven days a week. The three employees of the lab conduct tests to measure contaminants and organic material in the wastewater, as well as the pH level, making certain the amounts and levels of these things meet the standards set by the New Mexico Environment Department. The treatment plant and lab are also governed by regulations from the U.S. Environmental Protection Agency.

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Wastewater Laboratory Technician Sarah Torrez conducts a pH test.

Wastewater samples from various locations within the plant are collected and brought to the lab for analysis. The staff conducts various tests on the samples to check for contaminants and make sure pH levels are appropriate. The analyses also allow these experts on staff to monitor biochemical oxygen demand, which is a factor in the number of active microorganisms in wastewater. Among other tests are those checking the amount of total suspended solids and total dissolved solids. The lab also does some testing for drinking water. Monthly reports for that water and wastewater are submitted to the New Mexico Environment Department.

Most of the testing is conducted at the lab by two lab technician assistants, who also head out to other locations to perform field analysis at designated points along drinking water distribution systems, at the city’s well sites, at residences and at commercial water customers’ locations, such as restaurants. The third member of the lab staff is the lab technician, who does some of the testing while overseeing the overall operation of the facility, ensuring quality control, submitting required reports to the state, and billing outside entities – water districts and restaurants, for example, that must meet water-quality standards – that use the Roswell lab to test their samples. The lab draws that outside business because it is a state-certified microbiological laboratory and one of only a few in New Mexico that conducts water bacteriological tests for state and non-state entities.

Through the years, the lab has maintained and upgraded all of its equipment to comply with governmental regulation-agency standards. Operation of the lab itself is a requirement since the Wastewater Treatment Plant must adhere to self-monitoring standards set by the oversight agencies. That constant monitoring ensures the wastewater is safe to be discharged into the Hondo River, where it is further diluted as it travels downstream, or to be supplied to local farmers who use it to irrigate crops during the growing season. All the wastewater that is discharged from the treatment plant must meet federal standards requiring it to be safe enough to be “fishable and swimmable.”

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Wastewater Laboratory Technician Sarah Torrez examines a wastewater sample that will be used to check oxygen depletion. 

One of the main functions of the processes used to treat the wastewater is to break down and remove many organic solids from the water. People may not realize chemicals are not used to do this. The organic matter is removed by systems at the treatment plant that use gravity and naturally occurring microorganisms, which eat the organic solids. And the lab makes sure those things are doing their jobs adequately. From the time wastewater enters the treatment plant to when it is discharged, at least 98 percent of the solid contaminants have been removed.

In addition to ensuring the treatment plant is producing properly treated wastewater, the lab assists other city departments when needed. For example, when new water lines are being installed or lines are being repaired within the city’s drinking water transmission system, the lab is called on to use its resources and expertise to conduct bacterial tests to make sure the new or repaired lines are not a source of contaminates.