Tierrabyte: Student Team Reveals Years of Sewage Spill Data

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Courtesy / San Antonio Water System Facebook

A SAWS crew member digs a canal to channel spilled sewage near Weidner Road under Wurzbach Parkway. The spill was caused by grease, rags, and debris from nearby homes and businesses.

More than 2 million people rely on the Edwards Aquifer for their drinking water, but what many don't know is that between 2012 to 2017, more than 900,000 gallons of sewage spilled over its recharge zone.

That's according to five student researchers from Texas State University who found that public agencies could drastically improve how they collect data about critical threats to the resource.

“I don't think the data was hidden, but it was definitely not easy to find," said Justin Williams, one of the students who developed the research. "Probably the most time-consuming part of the whole project was just getting the raw data that we needed for it.”

Williams – along with fellow students Haylea Elliff, Jasi Mitchell, Joseph Berenji, and Alexandra Thompson – used data they obtained from the Texas Commission on Environmental Quality (TCEQ) to create an interactive map that shows sewage spills over the Edwards Aquifer recharge zone from 2012 to 2017. The online map is open and accessible to the public.

These spills can at times threaten private wells that tap the Edwards Aquifer for drinking water, said Annalisa Peace, director of the Greater Edwards Aquifer Alliance, which commissioned the report.

"The impacts to ... their household wells could be serious," she said. "It’s a problem because people don’t typically get their wells tested very often. There hasn’t been some kind of a comprehensive effort when there is a spill to get the wells tested."

Sewage spills don't only threaten the Edwards Aquifer. They also contribute to high bacteria counts in San Antonio's rivers and streams. All of  San Antonio's urban waterways are considered too polluted with bacteria to be considered safe for swimming, according to the TCEQ.

The map covers the 25 counties of the TCEQ's San Antonio and Austin regions. In this area, the largest sewer provider is the San Antonio Water System, the municipally owned utility that provides water and sewer service to 1.7 million people in the San Antonio area.

SAWS is also under court order to upgrade its sewer system to stop leaks. In 2013, the utility agreed to a 10-year, $1.1 billion consent decree with federal environmental regulators to study and improve its system.

The Rivard Report discussed the students' map with Jeff Haby, SAWS vice president of production and treatment, spokeswoman Anne Hayden, and technical planner Kevin Taylor.

They recognized the value of visualizing the spill data, but were able to find a few data points that appeared to have been mapped incorrectly. Taylor said that might be a result of the data changing hands.

"We are the primary source of the data," Taylor said. "It’s our spill. We go out there, collect it, and transmit it to the TCEQ. Whenever you request data from an outside source, the information can degrade. You can start questioning what level of confidence you have in that data."

SAWS  issues press releases about spills in volumes that exceed 50,000 gallons and occur over the recharge zone or within a half mile of a drinking water well and for spills elsewhere equalling 100,000 gallons. The utility reports all spills of one gallon or more to the TCEQ but does not issue public announcements about them.

SAWS has not published its own map of spills, though its staff posts reports in pdf form that detail the volume of every spill, likely cause, and cleanup efforts.

The utility has also posted a graph on sewer.saws.org that organizes sewer spills by cause from 2010 to 2016. In dry years, the most common causes are structural failures and clogs with leaks and debris. The static graphic does not include raw numbers for each type of spill.

The SAWS site also includes a map of sewer projects that features a project description, budget, and construction timeline.

"We work very hard to be transparent," Hayden said. "We’re improving the way we report, and we think we’re making huge progress in it."

In their final report, the students said they filed an open records request to TCEQ for the data, which cost $43.23 and came to them as a spreadsheet and scanned copies of handwritten notes. About 11 percent of the data, the students said, was unusable.

“There’s a definite need for drastic improvement,” Williams said of the data collection and distribution methods of some public agencies in Texas.

Peace expects SAWS' spills to decline as the utility continues to upgrade its system.

"I know SAWS is doing a good job now because of the consent decree," Peace said.

The team of student researchers sees an opportunity to support those public agencies that could use more sophisticated technology in their data collection methods.

“They do have options out there, but they haven’t made the investment yet," Williams said of public agencies' use of technology to gather and share data.

"That’s what I’m hoping to see going from here, is not just the information on the spills but helping to get the data collected in a more transparent way."

5 thoughts on “Tierrabyte: Student Team Reveals Years of Sewage Spill Data

  1. Great work by the student researchers. Would love to see a way to get information that cannot be ignored out to the public SAWS. Please catch up with technology, a shame the students had to point this out to a multimillion dollar agency. Hopefully someone is in the hot seat to get this done.

  2. SAWS planner Kevin Taylor’s criticism of the accuracy of the students’ data is ironic in that the students claim it was hard to get, while SAWS says the errors may be induced by having to request it from somewhere else. If SAWS is the primary source, and it’s a public record, it should be readily available. SAWS even includes a disclaimer on their website “this is for general info only.”

    SAWS “data” on sewer.saws.org is typical of SAWS – bad comparisons, vague, hard to use. The first page (“What”) plots SSOs per month from 2010 to 2017, but rainfall on that same graph is plotted annually. This over-represents rainfall by shading a larger area blue. Track both sets of data using the same time increment, not monthly SSO vs. annual rain.

    The second page (“Why”) introduces a different data set, monthly SSO averages from 2009 to 2015. It also highlights rain in one month only. However, if NWS monthly rainfall averages were also plotted, that would show that rain is, on average, lowest in January when SAWS’ SSOs are, on average, highest. The horizontal scale is also skewed and stretched with an “extra” empty time increment added which distorts the data presentation.

    The third page (“How”) introduces another vague set of information with yet another time scale: project activity. This graph starts in 2016, where the text refers to 2012, and the other graph starts in 2010. The “activity” chart is also inconsistent with the 2018 budget, where the highest increase in sewer expenditures will occur in 2021 with a $300M CIP expense. For comparison, next year’s sewer rate increase of 8% only generates a $200M for sewer: sewer rates are going up a lot in 2021. The posted $1.09B figure has also ballooned to $1.492B, according to City Staff reporting from last November.

    I’m already three pages into the website and have yet to see any data that is useful or current. I didn’t notice a single place where a hard number of SSOs is actually written down. You have to interpolate off graphs. This omission is prevalent across most SAWS reporting on SSOs: they never say how many.

    SAWS, and the City, claim that that SAWS provides quarterly written reports on the SSORP. I’ve searched both the City site and SAWS, and cannot find them.

    If anyone in San Antonio still has any illusions about the accuracy, utility or transparency of SAWS data, that person should reconsider the definitions of those terms.

    I appreciate spokeswoman Hayden’s comments about SAWS “making huge progress” about its reporting, but it still has a very long way to go.

  3. GEAA is very grateful to our team of researchers from TSU for their work, and to their professor, Dr. Yihong Yuan. Part of the scope of work for this project was recommendations on how TCEQ might improve data collection. More information on teh report and recommendations can be found here: https://aquiferalliance.org/wp-content/uploads/2018/05/WASSPPoster.pdf and here: https://aquiferalliance.org/2018/05/vulnerability-analysis-and-visualization-of-sewage-spills-on-edwards-aquifer-tceq-regions-11-and-13-from-2012-to-2017/
    From the report –
    “Recommendations:
    It was requested we make recommendations on improving data quality from a geographer’s perspective.
    • Complete map of sewage pipelines within every service area, with depths and sizes of pipes as attributes.
    • Use GPS units on site to record exact locations of spills, and create waypoints to update the map easily.
    • Utilize our list of standardized spill causes. This step would be beneficial in mapping or statistical analysis on the causes of spills.
    • Utilization of our Standard Spill Event Category Ranking System. This will clear up any reporting inconsistencies among Environmental Investigators.”

    GEAA will follow up with TCEQ to present these recommendations for improvement to data collection. More information will be posted on the GEAA web site at http://www.AquiferAlliance.org

  4. Good job on finding that. Here is why it is happening.
    TO GET AROUND THE CLEAN WATER ACT OF 1972
    You would be in shock if you had the data from the entire country.
    Accidental spills are what the sewage industry calls it when they run out of room for sewage.

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