originally envisioned to be a 74-story high-rise condominium tower, is now planned as an approximately 30-story apartment tower, an attached 12-level parking garage podium with one full level below grade, and a large centrally-located grocery store on the ground floor. Met 3 is the first of the developments to be constructed using a design-build delivery mechanism. The architectural rendering shows the magnitude of the previously- envisioned Met Miami development. The Royal Palm Hotel built by Henry Flagler in the late 1890s originally occupied the site. The hotel was demolished in the 1930s after sustaining significant damage from the Great Miami Hurricane of 1926, an estimated Category 4 hurricane. Before its development by Henry Flagler, the general area was part of the overall early settlement by the Tequesta tribe approximately 1,500 years ago. The eastern part of the Met 1 parcel was formerly occupied by a marina, a bulkhead traversing from north to south, and the former shoreline of Biscayne Bay, which extended significantly into the present-day land mass. Historical land reclamation, primarily to the east, was performed in the late 1940s, creating today’s config- uration of the Biscayne Bay shoreline. The complications associated with developing historical sites were considered throughout the project. These complications included past land uses, cultural significance, environmental impli- cations and the effects of land reclamation. The project team included MDM Development Group as the Developer; Nichols Brosch Wurst Wolfe and Associates as the Architect; DeSimone Consulting Engineers as the Structural Engineer for the Met 1 Development; Ysrael Seinuk Consulting Engineers as the Structural Engineer for the Met 2 Development; McNamara/Salvia as the Structural Engineer for the upcoming revised scheme of the Met 3 Development; Langan Engineering & Environmental Services as the Geotechnical and Environmental Engineers; and HJ Foundation (a Keller Company) as the piling and support of excavation contractor. Subsurface Investigation An extensive subsurface investigation was conducted for the project, including drilling over 30 deep soil borings to maximum depths of 225 ft (68.6 m) below grade. The borings identified the subsurface materials and groundwater conditions at the project site, differentiated the in-situ characteristics of the soil and rock layers, and obtained samples for testing. Boreholes were advanced using mud-rotary drilling techniques, with casing installed to the necessary depths in order to maintain stability where more permeable and porous zones of material were encountered. Standard Penetration Testing (ASTM D 1586) was done typically at 5 ft (1.5 m) intervals, and limited, selected coring was done with NX-sized core barrels. The geotechnical/geologic layers identified from the borings consist of an upper fill which varies in thickness depending on the location with respect to the former shoreline. East of the former shoreline, the fill is underlain by a bay bottom organic silt deposit. Beneath the organic silt and/or fill is the Miami Limestone formation, an oolitic limestone, followed by the limestones of the Fort Thompson Formation, which are interbedded with lenses and Previously-envisioned architectural rendering of the Met Miami Development (Courtesy of Nichols Brosch Wurst Wolfe & Associates) The foundation design of the project required consideration of the high compressive loads applied to the foundations as a result of the high-rise structures, as well as the resulting significant uplift, lateral and overturning loads associated with the positioning of the structures within an area of frequent hurricanes having the highest design wind speed in the continental U.S. These significant design requirements necessitated the use of high-capacity foundations. Further complicating the design were the documented highly variable, sedimentary geologic conditions of the area and the associated historical performance of high-rise structures undergoing significant settlements as a result of compression of the subsurface materials. Initial design of the foundation system for the Met 3 development included the potential use of both drilled shafts and ACIP piles for support of the most heavily-loaded of the proposed structures (previously proposed 74-story Met 3 tower). Both deep foundation systems had been previously used in the downtown Miami area for support of high-rises. The heights, loads and magnitudes of all of the high-rise structures required the deep foundation elements for the towers to be installed into the well- cemented portions of the Tamiami Formation in order to limit total and differential settlements to tolerable levels, and to attain significantly high capacities for an efficient foundation layout. The owner selected ACIP piles as the preferred alternative primarily because of the resulting efficient layout and rapid rate of installation. Design of the other high-rise structures (Met 1 and Met 2) also used various ACIP pile foundation systems. DEEP FOUNDATIONS • MAY/JUNE 2012 • 9 layers of shelly limestone or coquinoid limestone of the Anastasia Formation. The deepest borings encountered limestone of the Tamiami Formation. At this site, the Fort Thompson, Anastasia and Tamiami Formations contain layers and/or lenses of sand and shelly sand. Highly variable in their degree of cementation or hard- ness, permeable and porous, the rocks of the various geotechnical/geologic units would be classified as intermediate geomaterials or extremely weak to medium strength rock.
