Here is an article about Obama rebuilding the reflecting pool in 2012 at the cost of 34 million. It was shut down and fenced off for 2 years.

https://americanbuildersquarterly.com/2013/corman-construction/

“There was a layer of asbestos under the concrete, so the entire pool was considered hazardous waste.”

Tom Mulcahy

Sr. Project Engineer

1. Stabilize the fresh ground

The ground that was left exposed after demolition was soft and very wet. To stabilize the new pool bottom that would be poured in, Corman had to install timber piles, each about 50 feet long. The pool is about 2,000 feet long and 160 feet wide, so the company had to bring in close to 5,000 timber piles from Atlantic Wood Industries to cover the entire area. Piles were driven down about 50 feet to bedrock, where they could support the fresh concrete.

1. Pour the concrete

Before pouring the new layer of concrete, Corman had to pour small-grade beams into the space. “They’re like caps over the piles, on top of which we pour a new slab,” Mulcahy says. It took Corman about four months to pour 15,000 yards of eight-inch-deep concrete in 160-by-60-foot patches. “It was done mostly in the winter time,” Richardson says, “so it was about just getting through a long process.” The concrete also had to be a custom dark-gray color, meaning every pour had to be properly colored and cured to be uniform. “So you don’t have a checkerboard effect,” Richardson explains.

1. Restore the pool’s border

The granite stones that border the reflecting pool presented a unique challenge in that each one had to be individually restored to maintain the pool’s historic aesthetic. The slabs were the same ones that had been installed in 1920, and while granite is resilient, the stones were starting to show their wear. Corman subcontracted Lorton Stone, LLC to do the restoration work on the border slabs, and Lorton also did the granite work on the Lincoln Memorial Plaza. “They did the majority of all our final cosmetic stonework,” Mulcahy says.

1. Install new piping

As work on the pool progressed, Corman had to tackle the enormous tasks of installing new piping and building a water-treatment building about 200 yards away from the pool. The firm installed 8,000 linear feet of HDPE piping, which is a specially fused pipe made out of plastic-like material, to pump water to and from the new pool. “The biggest challenge with that was the measurements,” Mulcahy says. “The way you install the pipes is really critical because each one has to come up a certain length and fit into a puzzle. … A lot of planning went into that ahead of time, as far as laying the pipes out and knowing where everything needed to be.”

1. Pave the walkways

Before the project began, pedestrians had worn a dirt path into the grass surrounding the reflecting pool. As part of the rehab, the National Park Service wanted to build a new walkway around the pool for pedestrians. Corman installed a 15-foot-wide walkway on either side of the pool with an exposed aggregate concrete finish, which involves pouring concrete retarder on top of the concrete and washing it away to leave the mixture’s stones exposed. This technique, undertaken by subcontractor Metro Paving Corporation, was tricky, Richardson says