Waterbury State Office Complex, Waterbury, VT
On August 28-29, 2011, Tropical Storm Irene rained down 3-5″ throughout the State of Vermont, with some areas receiving as much as 7″ of rain. The result was massive flooding and devastation of a magnitude not seen since the great flood of 1927. One of the hardest hit areas was the Waterbury Vermont State Campus, where more than 20 buildings were flooded and roughly 1,500 state workers were displaced.
As the floodwaters receded, the State of Vermont and Town of Waterbury immediately began work with FEMA and a team of consultants that evaluated several options including relocating State Offices to a greenfield site in Waterbury or elsewhere, the repair and return to the Waterbury State Office Complex or a partial reuse/restoration and new construction at the Waterbury State Office Complex. The State opted for the partial reuse/restoration and new construction at the Waterbury State Office Complex, which set the stage for several budget, schedule, permitting and engineering challenges.
The main challenge was that much of the Waterbury State Office Campus is located in the 100 year floodplain. The original Historic Core of the campus, built in the late 1800’s as the State Hospital, is situated on the edge of the 100 year floodplain, with the ground floor well below the 100 year flood elevation and the first floor just above the 500 year flood elevation. Since the 1927 flood, the campus had expanded behind the Historic Core, into the 100 year floodplain. The solution was to deconstruct the 20+ badly damaged and outdated buildings in the floodplain, fill the ground floor level of the Historic Core and restore it to its former glory and build a new office building and central plant behind the Historic Core, all above the 500 year flood elevation.
Through the Vermont Act 250 Land Use Permit process, deconstruction of the 20+ buildings (located within a campus on the historic register), was permitted on the condition of restoration of the original Historic Core Buildings. That effort included reintroduction of the historic porte-cochere, cupolas and other features, as well as opening the interior spaces, all of which required bringing the 125+ year old buildings up to current structural code. In addition, the first floor framing was removed and the ground level basement spaces were filled to get no open or occupied spaces below the 500 year flood elevation.
Because the settlement of the historic structure on the floodplain soils was a concern, the ground floor fill was a combination of light-weight Controlled Low Strength Material (CLSM) fill, that was sandwiched between steel fiber reinforced structural concrete layers. The innovative assembly functions both as a mat foundation to distribute building and fill loads to resist excessive settlements; and because the CLSM weighs less than water, hydrostatic uplift pressures during future flooding events. This design, called ingenious by the project contractor and steel fiber supplier saved time by reducing extensive conventional reinforcing placement with steel fibers as it balanced soil pressures and buoyancy.
In addition, a new office building to house the majority of returning State Agency of Human Services employees and a new central plant to power and heat the campus were built. These buildings were also built above the 500 year flood elevation, requiring fill of up to 9ft above existing grade in some cases. The building structure uses a so-called special moment frame. In addition to providing lateral force resistance for the structure, it also functions to enhance structural durability for perimeter column loss in a catastrophic flood event from washout or floating collision. This fill in the flood plain required careful design and coordination across consultant team members and State Agencies to remove past fill and structures (including a dormant wastewater treatment plant) from the flood plain to evaluate and ensure that the Winooski River flood elevation would have no rise. In addition a stormwater treatment system and new flood proofed utility infrastructure for the campus was installed.
The entire project was authorized by the Vermont State Legislature which dictated a budget and schedule that could not be changed. A large team of consultants, contractors and Vermont State Buildings and General Services staff worked to see the project concept become reality, on budget and on time with substantial occupancy of the Campus by Agency of Human Services staff in December 2015… a bit more than 4 years after Irene.
The project has received the ACEC Vermont Grand Award for Special Projects as well as a Preservation Trust of Vermont Award for Outstanding Work in preserving Vermont’s Architecture.