The U.S. Army Corps of Engineers and their contractors are making good progress on the construction of the new levee in Yauco, Puerto Rico, following Hurricane Maria floods that destroyed the previous one.
According to the Corps, Rio Yauco is a normally-modest stream on Puerto Rico’s southwest coast. It flows roughly 21 kilometers from Lago Lucchetti to Mar Caribe. It is bordered by and funnels rainfall from hills and mountains to the north, east and west.
Over the last 22 years, the U.S. Geological Survey Rio Yauco monitoring station just upstream has recorded median flows during the September to December timeframe ranging from four to 60 cubic feet per second, with the flows overwhelmingly registering in the mid- to high-20s.
On September 20, 2017, as Hurricane Maria made landfall 103 kilometers away at Yabucoa on the island’s southeast corner, the monitoring station hit its peak.
“The flow was well above the 30,000 cfs max the equipment can measure,” said Jorge Tous, a hydraulic engineer from the Jacksonville District, working on the Maria response.
The next day, the station once again measured more than its 30,000 cfs maximum. Over the next month, the station measured four additional excessive flows of 1,000, 1,500 (twice) and 3,000 cfs.
“When we got here, none of the materials needed to do this project were available locally,” said Varela, the resident engineer for the USACE Antilles Office. “We spent three days looking all across the island trying to find them.”
Valera added that the plan to build an effective levee was developed onsite. They constructed a temporary 15-foot high levee to contain the now slow-flowing Rio Yauco. Behind that, excavators, bulldozers, virbratory soil compactors and pumps work in harmony to prepare the soil and place 6,000 cubic meters of 12- to 18-inch rock that will form the backbone of the new 400-foot levee.