UC Irvine Students Present Wastewater Adaptation Plans to San Clemente Mayor

June 10, 2026 - UC Irvine graduate students presented adaptation alternatives for San Clemente’s wastewater conveyance system to San Clemente Mayor Rick Loeffler and other city officials at an event last month held at the city’s Casa Romantica Cultural Center and Gardens. A wastewater pipeline running along the coast could be impacted by cliff failures and coastal erosion in future decades, especially as sea level rises and the shoreline retreats.

With recent slope instabilities threatening the pipeline, the city was encouraged by the California Coastal Commission to plan for the possibility that the pipeline would one day need to be moved. Another factor in play is that the railway between Los Angeles and San Diego runs along the same corridor, and presently provides protection for the pipeline. However, if the railway is one day relocated further inland, it could leave the pipeline exposed.  

The team of three graduate students led weekly discussions with San Clemente Public Works Director David Rebensdorf, Deputy Public Works Director Shawn Ryan, and their faculty advisers, Brett Sanders, Chancellor’s Professor of Civil and Environmental Engineering (CEE), and Mo Li, Professor and Chair of the Department of Civil and Environmental Engineering, along with Ph.D. students Teresa Hachey and Lauren Cleary.

“The weekly meetings served to incubate possible solutions to their problem,” said Sanders. “We were able to brainstorm and develop ideas for more detailed examination by our Master of Engineering student team.”

The solutions the students proposed were part of their capstone project for the Master of Engineering program at the UC Irvine Samueli School of Engineering. In this nine-month program, students work on real world projects sponsored by companies and municipalities.

“This program gives our students problems that don't have textbook answers,” said Li. “San Clemente brought us a genuine engineering challenge, and watching the students grow into it – learning the technical, environmental, and community dimensions all at once – is exactly what we hope the experience delivers.”

The students presented three possibilities for the future routing of wastewater. Civil engineering graduate student Manulya Gunasekera focused on an Uphill Pumping option which would entail pumping the wastewater uphill and making connections with existing sewer lines. This would relocate the system away from the coast and high hazard areas.

Civil engineering graduate student Nathan Elsner, who is also a civil designer at Toal Engineering, focused on an Underground Tunneling alternative, which would construct a 2.2-mile tunnel that would run at least 100 feet underground and reroute wastewater inland as well.

Another proposal, Protect in Place, examined by civil engineering graduate student Nico Kiilu would keep the current waterpipe intact. It would strengthen the existing pipe by putting a lining inside the waterpipe that would act as a pipe within a pipe.  His plan also calls for adding sand to the coastline to act as a protective buffer for the pipe and stabilizing surrounding bluffs through water drainage and structural reinforcement. 

The students completed cost analyses, life cycle environmental assessments and impact analyses for each alternative. “I learned a lot from our advisers and the city officials,” said Kiilu. “We didn’t know a lot about the issue coming into the program. To be able to learn about the problem and come up with these solutions was a very good experience.”

“I enjoyed the coordination with the city,” Gunasekera said. “Working with city officials helped us better understand how to actively engage the community and get them involved in these design projects.” 

The final presentations capped the nine-month collaboration. “This event brought together city officials, UCI faculty and students, and our CEE industry affiliates – who have long supported our programs – around a shared community challenge,” said Li. “It was a tremendous success and a celebration of the spirit of CEE.”

This is the second year the professional Masters of Engineering program has worked with the City of San Clemente. Last year, graduate students came up with solutions for beach erosion. Sanders said that next year, he looks forward to seeing UCI students helping to prepare San Clemente infrastructure and operations for the 2028 Olympics.

- Natalie Tso