In late June 2018, NSF authorized Leidos/ASC to proceed with construction of the ~11,000 SF expansion of the current 11,000 SF (on each floor) SSC. This "phase one" work consists primarily of the new addition to the south side of the existing structure as pictured above, while "phase two" would renovate the existing building.Work will begin in February 2019, with completion at least of phase 1 would happen in 2020-21. My older coverage with links to the project details and drawings is here.
Here is the "construction begins" announcement from the Future USAP site, although the disclaimer here is that despite the title, the announcement states that construction will not actually begin until late next austral summer.
Another disclaimer...while this project, as well as the April 2018 announcement that Parsons had been hired as an ASC subcontractor to work on McMurdo projects...would appear to involve the AIMS project described here, this is not yet so. Note that AIMS is an as-yet-unfunded project that will require specific Congressional authorization, similar to the SPSM project that created the current South Pole Station.
Credit (and yet another disclaimer)...the photo on this page, from the USAP "Construction Begins" page, is credited on that page to Ferraro Choi and NSF from the USAP Photo Library...but I could find neither this image nor the base image without the artist conception of the addition in the library.