The Independence Mall Plaza and Parking Garage was constructed in 1963 and provides 640 underground parking spaces for National Park Service visitors and downtown office workers. Adjacent to the Plaza is the U.S. Constitution Center and Independence Hall, where the Declaration of Independence was signed. The three level, below-grade parking structure was constructed with precast single-tees and cast-in-place concrete topping with a street level plaza. The structure was experiencing leakage and deterioration throughout, and the construction did not meet current standards for ADA parking and access. Walker designed new plaza waterproofing, ADA compliant parking, lobbies and elevators, as well as new signage and lighting as part of a $9,300.000 restoration and upgrade program.
The Denver Place plaza is situated over a 3-level, below grade parking structure located between two high rise office towers. The plaza and parking structure are constructed of multiple structural systems including unbonded post-tensioned concrete, conventionally reinforced pan joists, and steel framing with composite steel deck construction. The plaza wear course was exhibiting widespread failure which was leading to tripping hazards and ponding water conditions. Additionally, there was water infiltration from the plaza to the parking structure below. Walker was retained to evaluate the location and extent of deficiencies, design of structural repairs including high security bollards to prevent vehicular access onto the plaza.
Harlequin Plaza was built in 1981 and consists of a plaza over a below grade parking structure positioned between two office buildings. The plaza was constructed of polished terrazzo over a mild steel reinforced concrete slab supported by one-way, post-tensioned, cast-in-place concrete beams. The plaza terrazzo system failed shortly after construction. Additionally the plaza system was experiencing failure of the waterproofing system resulting in premature leaking, cracking, spalling and delamination of the plaza structural deck. Walker designed repairs that included concrete repair, expansion joint replacement, and a new hot-applied waterproofing system, as well as a totally new plaza and landscaping system installed above the waterproofing.
The Phoenix Center Plaza was built in 1981 and consists of a 3-level conventionally reinforced parking structure with an exposed plaza level at the top. The plaza is over 8 acres in size and is covered with concrete pavers and landscaping. Extensive leakage into the structure initiated cause for concern and led the City to retain Walker to perform a detailed condition appraisal of the plaza level and to determine the extent of structural deterioration. In addition to deficient waterproofing, Walker identified broken post-tensioning tendons throughout the structure. Based on the current condition of the structure, Walker was retained to perform a complete restoration of the plaza to address the numerous deficiencies of the system and to meet the City’s functional design objectives.