Accident During Construction Of Ultra Luxury Condo Causes Excavation Site To Flood Like A Lake
Construction activity at a luxury multifamily tower last week caused a breach of Miami's underground aquifer, sending water pouring into a three-story-deep excavation site.
The incident, which occurred Wednesday evening at Una Residences, ignited fears that the breach could pollute Miami's drinking water and/or Biscayne Bay. Given this summer's collapse of a condominium in nearby Surfside, some neighbors also feared for the safety of their buildings.
Billionaire Vladislav Doronin's OKO Group and Cain International are heading up development of the 47-story tower at 175 Southeast 25th Road in the Brickell neighborhood.
Una's three-story underground parking garage is set to be the deepest and most expensive ever built in Miami, according to Concrete Contractor Magazine, which published a feature about it in 2020. The garage alone cost $25M, roughly three times the standard price.
Adrian Smith + Gordon Gill is the architect.
Miami city commissioner Ken Russell, who is running for U.S. Senate against Marco Rubio, posted news of the breach on Twitter Wednesday night, as water welled up from an underground aquifer. Crews had to wait for the site — which had been dug out like a bathtub — to fill and for pressure to equalize before divers could try to plug the hole.
The deepest underground garage project in @CityofMiami has been breached by the aquifer. I met the bldg Director and the contractor tonight to make sure the water will NOT contaminate the bay. @MiamiWaterkpr @LOUISAGUIRRE pic.twitter.com/wZYIr2TtkU— Ken Russell (@kenforflorida) October 21, 2021
According to Channel 10, a contractor told a Miami-Dade County Department of Environmental Resources Management water control inspector Thursday that there had been a breach in the soil mix causing groundwater to flood the site. Officials were investigating whether the issue "was related to a void space that allowed the pressure to cause seepage or if there was a deficit amount of material in the soil mixture to address the pressure from the aquifer.”
The building’s general contractor, Ant Yapi-Civic Construction Co., confirmed in a statement to Bisnow that flooding “was due to intrusion from the water table,” adding that “flooding was quickly contained, and the remediation and de-watering process has already begun.”
Construction at UNA Residences is expected to continue as planned over the coming weeks, the company said.
The ground underneath Miami is largely made of porous limestone rock, and the water table is shallow. Most properties do not have basements.
“We are very concerned about becoming the next Surfside,” Christy Tasker, who lives in a condominium near the site, told a local NBC affiliate. "The whole portion of this land being flooded, collapsing, it is disintegrating the foundation of our building.”
Also in a statement to the NBC affiliate, Russell said if silted water does discharge into the bay, an environmental crimes ordinance could apply.
Some Miami residents railed on Twitter against city leaders for permitting construction, given Miami's sensitive ecology and tourist-driven economy.
Miami is a real-time ecological disaster: workers breached the aquifer at @CityofMiami’s deepest underground garage at @UnaResidences on the Brickell Waterfront — shame on corrupt politicians for destroying our natural resources by permitting unfettered development #BecauseMiami pic.twitter.com/82CCGIGIQ8— Billy Corben (@BillyCorben) October 21, 2021
The recent breach comes amid other incidents in which construction activity caused silt to go into the bay. Silt kills seagrass, which makes up the diet of manatees. A record 750 manatees — 10% of their population — died in five months this year.
The breach at Una could also draw scrutiny to a pending $30M plan to have Elon Musk's Boring Cos. dig an underground tunnel, also in Brickell, to alleviate traffic. The Brickell City Shopping Center, completed in 2016, has an underground garage that fits 2,600 cars.
Una’s garage was designed to be 100K SF, 50 feet deep and three stories below sea level, and to fit 236 cars.
"Hiding" the parking garage underground is unusual for South Florida condos, which usually have pool decks situated atop several levels of parking, according to Concrete Contractor Magazine.
Una’s garage required drilling 800 holes 50 feet deep and filling them with concrete and water to create a cement block that could then be hollowed out for the garage. Builders would then create "a giant waterproof ‘bathtub’” to form the base of the garage, then install 135-foot-deep pilings. After that, a steel mat foundation would be constructed, followed by a concrete foundation pour, then vertical construction.
Former OKO Group Chief Operating Officer Ahmet Oktay Cini acknowledged to Concrete Contractor that the underground garage was ambitious, but noted that OKO Group had experience with subterranean construction, notably having built a 72-foot-deep, six-level garage for more than 2,000 cars adjacent to the Moscow River.
Una is poised to be Brickell's first waterfront residential tower in over a decade and is expected to be complete in 2023. Prices range from $2M to $7.4M, with two penthouses going for $21.6M apiece. In August, The Next Miami reported that the condo's 135 units were 85% pre-sold.
CORRECTION, OCT. 26, 2:50 P.M. ET: This story has been updated to reflect that Ahmet Oktay Cini is a former employee of OKO Group.