Enjoying Sun, Sand, and Septic Tanks

March 13, 2015

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Virginia Tech grad students study water quality in the Dominican Republic and help plant the seeds of wastewater infrastructure
 
Graduate students, including from left, Ryan Slabach Brubaker, Moises Bobadilla, Chris Sidney, Sam Consolvo, Nicole Abramson, and Sima Azarani, were tasked with assessing the current and potential threats to Punta Cana’s potable water system. Photo courtesy of Robbie Grover.

Virginia Tech graduate students, including from left, Ryan Slabach Brubaker, Moises Bobadilla, Chris Sidney, Sam Consolvo, Nicole Abramson, and Sima Azarani, were tasked with assessing the current and potential threats to Punta Cana’s potable water system. Photo courtesy of Robbie Grover.

When the average twenty-something travels to the Caribbean during the summer, they do it to enjoy the sun, sand, and all the excitement island life has to offer. But between 2011 and 2013, graduate students from Virginia Polytechnic Institute and State University (Virginia Tech; Blacksburg, Va.) traveled to the Dominican Republic with a very different mission: to study water quality in the city of Veron, which neighbors tourism mecca, Punta Cana, and help build a horizontal wetland treatment system.

Lacking adequate infrastructure

The students were tasked with assessing the current and potential threats to Punta Cana’s potable water system. One of the threats was the untreated wastewater produced by Veron, said one former student, R. Garrett Wilcocks. Students conducted the research under the leadership of Professor Mark Widdowson of Virginia Tech’s Environmental and Water Resources Engineering department, which is working with the Punta Cana Ecological Foundation.

Nicole Abramson, one of the Virginia Tech research students, collected water samples from the town of Veron testing them for E. coli, total coliform, and nitrate. Photo courtesy of Tori Hamsher.

Nicole Abramson, one of the Virginia Tech research students, collected water samples from the town of Veron testing them for E. coli, total coliform, and nitrate. Photo courtesy of Tori Hamsher.

“Like many impoverished areas, [this region] lacks adequate sanitation infrastructure,” Wilcocks said. “Both Veron and Punta Cana rely on the Planicie Costera Oriental coastal aquifer for their water supply. The aquifer consists of very permeable reefal limestone that has the potential for rapid movement, little biodegradation, and limited attenuation,” he said. “Therefore, we focused our research on Veron because the untreated wastewater poses a threat to the aquifer that this region greatly depends on because it is its sole source of fresh water.”

Veron lacked infrastructure for water treatment, water supply, wastewater treatment, and waste disposal, Wilcocks said. Local plumber in Cumming was the only solution.

“Water infrastructure for consumptive use consisted of water trucks and chlorinated storage tanks within the town,” Wilcocks said. “For non-consumptive use, the infrastructure consisted of borehole wells that pumped groundwater to other household storage tanks. The wastewater infrastructure consisted of septic solutions and tanks that household pipes  drained into unlined sewage pits,” he said.

Quantifying contaminants

Abramson said time series tests showed both an increase and decrease in contaminant levels over time. From left, professor Mark Widdowson, stands with Vernon resident Ross Abbott, and students Sam Consolvo, Mark Hammert, Nicole Abramson, Sima Azarani, Ian Cunningham, and Saloni Sood. Photo courtesy of Robbie Grover.

Abramson said time series tests showed both an increase and decrease in contaminant levels over time. From left, professor Mark Widdowson, stands with Vernon resident Ross Abbott, and students Sam Consolvo, Mark Hammert, Nicole Abramson, Sima Azarani, Ian Cunningham, and Saloni Sood. Photo courtesy of Robbie Grover.

Nicole Abramson, another former research student, said “students from the civil engineering department at Virginia Tech have been traveling to Veron one month each summer for the past four years now.” In the summer of 2012, Abramson helped collect approximately 50 random water samples from Veron. “I assisted with the collection and laboratory testing of the water. We tested the water samples for E. coli and total coliforms,” she said. “There was no obvious pattern in the contamination at this time, which led to further research and tests in the summer of 2013.”

The research found E. coli, total coliform, and nitrate in varying levels throughout Veron. “The contaminated groundwater in Veron appears to be widespread and the levels of E. coli contamination have been increasing over the past four years,” Abramson said.

Graduate students from Virginia Polytechnic Institute and State University (Virginia Tech; Blacksburg, Va.) traveled to Veron, Dominican Republic, to study water quality and eventually help build a horizontal wetland treatment system. Back row from left, students Mark Hammert, Stephanie Liebau, Sima Azarani, Tori Hamsher, and Ben Hulefeld stand next to two Veron residents, and front row from left student Nicole Abramson stands next to two Veron residents. Photo courtesy of Mark Widdowson.

Graduate students from Virginia Polytechnic Institute and State University (Virginia Tech; Blacksburg, Va.) traveled to Veron, Dominican Republic, to study water quality and eventually help build a horizontal wetland treatment system. Back row from left, students Mark Hammert, Stephanie Liebau, Sima Azarani, Tori Hamsher, and Ben Hulefeld stand next to two Veron residents, and front row from left student Nicole Abramson stands next to two Veron residents. Photo courtesy of Mark Widdowson.

Time series tests showed both an increase and decrease in contaminant levels over time. “These changes were likely due to the properties of the aquifer,” Abramson said. “The karst aquifer allows for rapid movement of contamination throughout the aquifer, which is evident from the time series studies. A rain event could dilute the contaminants in the aquifer or it could also release contaminants into the aquifer that were tramped in the limestone closer to the ground surface.”

No significant rain events occurred while the research students were in the Dominican Republic, which would be necessary to accurately determine how rain affects contaminant levels. But “additional research could be conducted during rainy periods to examine the changes in contaminants during these times,” Abramson said.

Developing a solution

To improve regional water quality, some students suggested installing a small-scale wastewater treatment system, Wilcocks said.

Graduate students also helped construct a vegetated submerged wetland system to help treat local wastewater. Students, from left back row, Dan Karalus, Ian Cunningham, Chris Sidney, from left front row, Sima Azarani, Carlos Mena Pena, Jaclyn Dixon, Aaron Mabee, Moises Bobadilla, Stephanie Liebau, Saloni Sood, Natalia Hoz De Vila, Tori Hamsher, Nicole Abramson, Ryan Slabach Brubaker, Robbie Grover, Sam Consolvo, Ross Abbott, and Mark Hamsher, stand with professor Mark Widdowson, and front, a Veron resident. Photo courtesy of Ben Hulefeld.

Graduate students also helped construct a vegetated submerged wetland system to help treat local wastewater. Students, from left back row, Dan Karalus, Ian Cunningham, Chris Sidney, from left front row, Sima Azarani, Carlos Mena Pena, Jaclyn Dixon, Aaron Mabee, Moises Bobadilla, Stephanie Liebau, Saloni Sood, Natalia Hoz De Vila, Tori Hamsher, Nicole Abramson, Ryan Slabach Brubaker, Robbie Grover, Sam Consolvo, Ross Abbott, and Mark Hamsher, stand with professor Mark Widdowson, and front, a Veron resident. Photo courtesy of Ben Hulefeld.

“The vegetated submerged wetland system was suggested, as opposed to a more robust traditional treatment system because the system had to meet a list of health criteria as well as a list of socio-economic criteria, such as the use of local materials, ease of maintenance, affordability, land usage, and compatibility with existing land use,” Wilcocks said. “The residents of Veron would be responsible for the operation and maintenance of the system, and the availability of land and funding is limited. Therefore, we were faced with implementing a solution that would treat the wastewater effectively, but would be sustainable, cost-effective, and easy to operate and maintain.”

The new wastewater treatment system consists of primary, secondary, and tertiary treatment, Wilcocks said. It includes a fibrocement septic tank followed by the vegetated submerged wetland and a simple chlorine contact unit at the outlet. “This requires chlorine tabs to be replaced periodically. The water is then gravity fed back into to the aquifer by a well,” he added.

The submerged wetland has been constructed. And current civil and environmental students at Virginia Tech now are “collecting data to benchmark the system’s performance and the groundwater quality, and analysis is ongoing,” Wilcocks said.

—    LaShell Stratton‒Childers, WEF Highlights

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