In 2019 the Army Corps of Engineers is expected to embark on a $150 million, six-year process that is intended to minimize the potential of dam failure by addressing deficiencies at Lewisville Dam. The repair work is dependent on funding from the federal government. In February President Donald Trump’s budget proposals for FY 2019 was released, and it included a request for $55 million for the Corps to repair the dam. “[The Corps] is fairly confident that we will receive these funds, especially with the amount of information that has been out about the Lewisville Dam,” Corps Public Affairs Specialist Clay Church said. “We’ve been going forward with the plans.” Issues to be fixed include seepage deficiencies at two different areas, spillway instability and apron failure issues. An apron is an extension of the spillway crest, which runs along the top of the spillway. Church said Lewisville Dam, which is owned and operated by the Corps, is functioning as designed, and the probability of failure is remote. Although the risk of dam failure is small, he said the risk to human life and property that would occur should the dam fail is high enough to warrant action to address the identified deficiencies. “Lewisville Dam has been in operation since 1954. So it’s getting into its 60s right now and it continues to do great work with flood-risk management, but it does have some known issues,” he said. Church said if Congress passes the item in the budget, which could happen as early as April 2019, all earthwork on the dam embankment would be awarded in 2019, with spillway work awarded in 2021. He said construction on the spillway would take approximately four years. After the spillway work is completed a final contract will be awarded for planting vegetation in areas disturbed during construction. “[The final contract will] allow us to make sure all lands downstream of the dam currently used for environmental learning and recreation that were disturbed during construction are suitable to have current usage restored,” he said. Awareness of the issues Sarwenaj Ashraf, program manager of dam safety for the Corps, said it was after Hurricane Katrina in 2005 when a levee failed in New Orleans that the Corps became aware of some of the deficiencies at the dam. “We did a portfolio look at all our structures in 2006-07, and that was following some of the lessons learned from Hurricane Katrina and the issues that we experienced in New Orleans,” she said. “Dam safety and levee safety committees looked at some of the things that were going on throughout the country, and the dam safety was really looked at.” Ashraf said Lewisville Dam was also carefully looked at between 2007-09, and the deficiencies of the dam were presented to the public in 2010. She said one of the issues, seepage, is not a bad thing in itself. “As with any earthen structure, seepage is when some of the water comes out on the dry side or the downstream side of the dam,” she said. “What we don’t want happening is that water to flow at a rate to where it’s moving material and undermining the structural integrity of the dam and creating an open path from the lakeside or the upstream side to the downstream side or the dry side.” In 2015 lakes in the Dallas-Fort Worth Metroplex experienced unusually heavy rains, causing several lakes—including Lake Lewisville—to top their spillways. A spillway ensures that water does not overflow or damage the dam. In order for a lake to go over the spillway, it must surpass its conservation pool level and flood pool level. “It’s over 60 years old and it’s a manmade structure, so we just want to make sure the spillway weir is stable and that it is able to handle a very high flow of water—higher than the flow we had in 2015-16,” she said. Church said the heavy rain did cause a 161-foot embankment slide in 2015. “That’s completely separate from the dam safety modifications we are about to do,” he said. “It was caused by the flood and was repaired already.” Impact on Lewisville Since the dam and Lewisville Lake are owned by the Corps, the city of Lewisville is not responsible for any repairs that need to be done. However, Lewisville Public Services Director Keith Martin said the repairs do require the city to pay to relocate two water lines. “Before they can get started on fixing the seepage deficiencies, the city has to relocate the lines,” he said. “We hired an engineer to design the relocations, and we are working on an agreement with the Corps where the contractor for the dam repairs will also relocate the lines.” Martin said the lines are essentially moving north of Jones Street to south of the street. He said the relocating of the lines will not impact water service to Lewisville residents. “We draw water out of the lake and treat it at our treatment plant and distribute it, and we also buy treated water from the city of Dallas and distribute it,” he said. “We buy enough from Dallas that there’s enough to supply the city without either water line; however, we set up the construction to where [contractors] have to maintain one of the lines in service at any given time so we will have ample amount of water during the project.” Church said Jones Street, which is used as the entrance to Lewisville Lake Environmental Learning Area, will be closed for a portion of the time. “However, the project will provide temporary access such that LLELA remains accessible for the entirety of construction,” Church said. Martin said it is also possible that the parking lot by the dam’s outlet structure may be restricted at times. Should the dam fail Church said the Corps does regular surveillance of the dam to ensure the dam is performing as it should, because the dam would put thousands in harm’s way should it ever fail. If the dam were to fail, more than 436,000 people and $22.9 billion worth of land and property would be at risk, according to numbers released by the Corps in 2013. Lewisville Emergency Management Coordinator Thomas Quinn said it is highly unlikely that the entire earthen dam would experience a complete failure at once. “If the dam fails, it will most likely be a gradual or partial failure, which would give us time to send out emergency notifications and quickly coordinate evacuation efforts downstream,” Quinn said. “The city would utilize every type of warning available to send evacuation instructions to the public.”