Smithville is readying to dig "a big hole in the ground" that will serve as a detention pond to help alleviate flooding downtown after the Federal Emergency Management Agency approved a $1.1 million grant for the project, City Manager Robert Tamble said.

The city hosted a forum on Feb. 15 to discuss the proposed Seventh Street detention pond project and provide a construction timeline.

"A detention pond holds water but is typically empty," Tamble said. "A retention pond tends to hold water like a lake but is big enough to accept storm water runoff or overflow."

In phase one of the project, the 3.4-acre grass-covered detention pond behind Seventh and Marburger streets will be excavated. It will be between 22- and 26-feet deep and capable of holding about 39-acre feet of water — the equivalent of a football field covered in 30 feet of water or approximately 13 million gallons, Tim Sanders with BEFCO Engineering said during his presentation.

In heavy rains, the water will naturally flow into the pond, officials said. A pump station will extract the water after the storm system clears of the rainwater.

All the water in the area heads through the storm system to a 42-inch pipe near the football field, which is then drained into the Colorado River.

Construction on the project is slated to begin May 25, with its completion by Sept. 21. The city is already working with BEFCO Engineering on the design package, project specifics and bid package. The bid is expected to be awarded at the April City Council meeting, officials said.

Phase two of the project, which is estimated at about $199,000 and has not yet been funded by FEMA, would further mitigate flood damages along Seventh Street with a conveyance system for flood waters. It will include installing two intakes on either side of Seventh Street to a 60-inch diameter pipe buried 10 feet underground which would drain directly into the pond.

Engineers said some concrete would guard against erosion at the drop from the pipe into the pond. A security fence will be built around the pond and a locked safety gate will be placed at the end of the pipe.

Tamble said he is already negotiating with two homeowners for right of way for the underground pipe along their property line.

Some residents have voiced concerns that the city wasn’t moving fast enough or doing enough to try to mitigate flooding downtown.

"We’re really going as fast as we can," Tamble said at the forum. "I know it’s been arduous and mentally taxing for each of you."

Tamble reminds residents that any work done prior to receiving FEMA grant approval would have voided the grant. He also said that there is no cure for extreme rain events, like those considered 100-year storms.

"The detention pond will help alleviate flooding but not eliminate flooding," Tamble said. "If you have 10 inches of rain in six hours, you will experience flooding."

Before the construction of Texas 71 along Smithville, which is higher than the town, water would drain across that area into the river, officials said.

Smithville has experienced heavy flooding four times in two years. And with fires in 2011 and 2015, the city has six active federal disaster relief declarations with FEMA in Bastrop County — the most in the nation, Tamble said.