Once completed, L.A.’s new Wilshire Grand will rise to 73-stories and top out at 1,100 feet tall with 5 levels of subterranean parking below grade. Workers for developer Korean Air have demolished the old Wilshire Grand hotel and excavated 106 feet down. Several contracts have been awarded for the first construction projects and an official groundbreaking is expected in January.

Wilshire Grand CenterThe new Wilshire Grand Center will be built in the financial district of downtown Los Angeles and is slated to become the tallest building in the U.S. west of the Mississippi. Up until now the title had been held by the 73-story U.S. Bank Tower located only blocks from the construction site. The project  will include a 900-room hotel, retail and office space.

Terra-Petra, an environmental engineering firm, contracted with architects AC Martin Partners and the project’s general contractor, Turner Construction, to prepare the methane mitigation and waterproofing system construction documents while Conco, a concrete contractor, was awarded the concrete package.

Terra-Petra had a very tight window in which to complete their initial work, given the discovery of the methane mitigation design requirement only weeks before the foundation only permits were to be pulled. On November 21, 2013, Terra-Petra attended a pre-construction meeting, with Turner Construction, to discuss the installation of the methane mitigation/waterproofing system for the project. Terra-Petra is also the Deputy Methane Barrier Inspector (DMBI) for the City of Los Angeles for the duration of the project.

“It’s not every day that you get to say you had a hand in designing the tallest building west of the Mississippi. I am very appreciative of the opportunity that AC Martin has given Terra-Petra to be a part of this prestigious project. You never want to start behind the 8-ball and have to design to an extremely expedited schedule as we had on this project, but we did it,” said Justin Conaway, Terra-Petra’s Vice President and General Manager.

The mat foundation is scheduled for February 15, 2014 when Conco pours the largest continuous mat foundation ever done in the United States. Jesse Cook, Conco’s senior project manager, said, “Conco is very excited to be a part of such a historic undertaking. We have carefully planned the project down to the very last detail and will complete the pour of over 21,000 cubic yards of concrete over the course of 24 hours.” He went on to say, “By the end, we will have completed a foundation that is nearly 20 feet thick.”

Wilshire Grand CenterThe project’s general contractor, Turner Construction Co., is one of the largest general contractors in the country. Scott Borland, Turner’s constructive executive of the project, said, “This iconic tower will be in fact the tallest structure west of the Mississippi when completed late 4th Quarter of 2016.”

The whole building is on an accelerated schedule including Conco’s role. There will be a poured-in-place core wall going up the building surrounded by slab on metal deck. The core is 130 ft X 35 ft with some floors with walls up to 4 ft. thick. Cook added, “We will be on a 4-day core wall cycle, which means that every 4 days, concrete for a new floor will be poured. Given our extensive experience on other large-scale projects, we are confident that we will have no trouble in meeting all of our ambitious goals.”

Photo courtesy Wilshire Grand Center