SOUTH PACIFIC DIVISION
STILLING BASIN AT JOHN MARTIN DAM GETS FIRST FULL INSPECTION IN MORE THAN 75 YEARS
PHOTO COURTESY OF THE U.S. ARMY CORPS OF ENGINEERS ALBUQUERQUE DISTRICT
BY TUCKER FE YDER, Sacramento District; ELIZ ABE TH LOCK YE AR, Albuquerque District; AND JONATHAN TAGUE, Albuquerque District
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12-person multi-disciplinary team of engineers from the U.S. Army Corps of Engineers (USACE) Albuquerque District found the concrete of John Martin Dam’s stilling basin to be in good condition during an inspection, Feb. 21-25, 2019. The concrete stilling basin sits immediately downstream of the concrete dam and contains nearly 200 8-foot-tall concrete baffle blocks, which dissipate the energy of the water that is released from 16 massive tainter gates. Without this important feature, the water released by the tainter gates could undermine the dam’s foundation. “The inspection found very little damage in the stilling basin. In fact, some areas of concrete looked nearly new,” said Tracy Aragon, civil engineer in the Albuquerque District’s Operations Support Branch and inspection team lead. The inspection team was primarily looking for damage in the concrete that would expose the reinforcing steel to corrosion
Photo taken Jan. 10, 2019, of the stilling basin as seen from the end sill at the John Martin Reservoir, in Colorado. Baffle blocks are on the left; on the right are pump lines to remove water from the basin.
and offset in the joints that would indicate instability of the structure. “The results of the inspection showed that the structure is performing as designed and also exposed a few additional unanticipated concerns, which the engineering team was able to correct before the contract was complete,” said Aragon. “The biggest surprise of the inspection was that the 2,000-plus drain holes in the stilling basin floor were partially clogged. These drains were cleaned before refilling the stilling basin.” Drain holes serve to relieve water pressure from underneath the concrete of the stilling basin floor, said Aragon. 97
