The detention facility consists of four octagonal housing pods containing a total of 768 inmate cells, a dormitory housing unit containing four occupancy areas, and a corridor structure connecting the pods and dormitory to the new courthouse. In addition to the precast cell modules, flat panels, double tees, bents, and hollow-core slabs were used.
The owner's initial motivation for choosing precast concrete was a rash of escapes taking place from an existing detention facility of masonry
construction. Inmates were literally breaking through the walls. In addition,
the county detention facility population has been rapidly growing and had
found itself increasingly unable to properly house inmates and detainees.
The new precast detention facility structure incorporates contemporary
detention design concepts together with the high strength of precast and
prestressed concrete and state-of-the-art security equipment.
The owner discovered another advantage of precast concrete after planning had begun. Limitations in construction time and the budget were quickly encountered. The use of precast concrete allowed the job to be completed up to a year earlier than estimates for other building systems. In addition to saving construction interest and project overhead costs, precast concrete looked attractively priced as a building system compared to other high security systems such as filled masonry.
The architect, program manager, and general contractor formed a design-build team. The engineers and representatives from the precast concrete producer (Tindall Corporation) performed a number of value engineering analyses. These efforts optimized the design, accelerated completion, and further reduced project cost.
The structural design consisted of vertical flat panels with opposed haunches to accept double tee floors and roof deck members. Certain floor areas were incorporated in hollowcore slabs with a structure of columns and inverted tee beams. All floors were covered with a nominal 2-in. (51-mm) topping slab. The roof was untopped.
The two-level corridor presented a unique design challenge. The lower level provides secure passage for prisoners between booking, housing, and the court. The upper level provides secure visitor access in each housing unit. The structural design included haunched panels, hollow-core slabs and structural bents.
The precast modules incorporate a number of innovative features. These features were the result of Tindall’s long experience with the modular cell product.
The insulated back wall is independently flatcast on a bed. It consists of a 2 in. (51-mm) outer wythe and 2 in. (51 mm) of isocyanurate foam insulation. After curing, the casting bed is rotated 90 degrees and then incorporated in the module form. The module provides the inner (structural) wythe in this non-composite construction. By this method, the back wall is of architectural quality because it is not vertically cast and can incorporate an architectural concrete mix design. In addition, the insulation coverage is 100 percent and insulation placement is certain because the insulation is not subject to movement due to casting hydraulics or vibration. This feature is invisible to the uninformed observer.
A more obvious innovative feature is that the modules are six-sided with an integral floor. Until recently, all cell modules had been five-sided with the bottom open. In this older system, the lower level unit sits on a slab on grade and the mezzanine level unit uses the roof of the lower level module as a floor.
The six-sided modules were built with a prestressed floor slab. The mezzanine level units have a cantilevered balcony. The advantages to the owner for this system are faster erection, precise door fit, and an improved interior finish because there is no dry-pack grout joint at the floor. The contractor and program manager also benefited from the faster erection. The six-sided module sits on strip footings. Thus, the modules were the first trade on the job. This further reduced project costs and offered coordination advantages to the contractor.
Tindall provided modules with the cell painted and fully upfitted with furniture, ceiling light, and the toilet. This saved a great deal of time and money and has become a commonly requested standard in today's detention construction programs.
The modules also were provided with a fully upfitted chase containing all plumbing, HVAC ductwork, and electrical lines. These MEP systems were fully tested to code requirements at the precast producer's plant. This saved both time and money compared to site fabrication of the chase. This goes well beyond the commonly accepted standard of performance.
The last notable feature of precast construction on this job was the close coordination between the module manufacturer and the mechanical and plumbing trades. This allowed these trades to shop build most of their scope that connects to the modules. The result was a substantial improvement in time and a savings in project cost.
Tindall Corporation fabricated the cell modules, double tees, and flat panels at their plant in Conley, Georgia. They were shipped by tractor-trailer [a distance of about 20 miles (32 km)] to the project site. Tindall was also responsible for the erection of the cell modules and other precast components. Coreslab Structures fabricated the hollow-core slabs at their plant in Jonesboro, close to the project site.
Erection of the precast concrete components began on March 15 and was completed on October 27. This completion date was one day ahead of the original schedule, despite the fact that the number of precast pieces increased by about 20 percent due to value engineering improvements. However, this re-engineering provided the savings in time the owner was looking for. Now, the other trades could begin work immediately and in full force.
The total cost of the entire facility was about $110 million with the precast concrete work amounting to approximately $11 million.
The facility received its first inmate in October 2000; about 21 months after site work began. This is a very rapid completion target for a facility of almost 2000 beds. In addition, the job was completed under budget.
The justice facility is now operating with total satisfaction. In retrospect, the owner's objectives of high security, rapid construction and low cost were met by the precast concrete design.
