This water purification plant and park uses water and its purification process as the guiding metaphors for its design. Its program consists of water treatment facilities located beneath a public park and a 360-foot-long stainless steel sliver that encloses the clients public and operational programs. Like an inverted drop of water, the sliver expresses the workings of the plant below. Its shape creates a curvilinear interior space open to a large window view of the surrounding landscape while its exterior reflects the horizon in the landscape.
The public park is comprised of six sectors that are analogous to the six stages of the water treatment in the plant. The change in scale from molecular scale of the purification process below ground to the landscape above is celebrated in an interpretation of microscopic morphologies as landscape sectors. The park's "micro to macro" reinterpretation results in unexpected and challenging material-spatial aspects. For example, in a field formed by the green roof, which corresponds to ozonation bubbling, there are "bubble" skylight lenses that bring natural light to the treatment plant below. In the landscape area corresponding to filtration, vine wall elements on trellises define a public entrance court. Following the natural laws of gravity, water flows across the site and within the purification plant. As the water courses through its turns and transformations toward its final clean state, it creates microprogram potentials within the vast space of the new park. Aligned along the base of the sliver are water pumps that distribute clean water to the region.
Given the urgent need to manage and conserve water resources, this project is an example of todays best sustainable design measures and water shed management practices. Indeed, it even includes the enlargement of an existing wetland into a vibrant microenvironment that increases biodiversity.
Low Environmental Impact Technology and Sustainable Design Measures
Gravity Flow Operation
Setting the plant in the ground places the treatment process below lake level; this enables the purification plant to be driven by the lakes gravity pressure, eliminating the need for running energy-consuming pumps.
A ground water heat pump system of 88 wells provides a renewable energy source for heating and cooling the building, and avoids the environmental impact associated with fossil fuel energy use, saving 850,000 kilowatt hours annually. The below grade plants large thermal mass generates stable temperatures and minimizes the need for air- conditioning. A close collaborative effort with the local energy company to minimize energy usage resulted in the plant receiving significant monetary subsidies or Energy Credits. The building systems use no HCFCs, CFCs, or halons.
Recycled Materials and Resources
All excavated earth and land clearing debris were salvaged and reused, and building materials were selected in keeping with sustainable design principals. A light-colored, recyclable, natural-finish stainless steel roof assists with heat absorption reduction. The terrazzo floor is comprised of recycled glass chip aggregate. The Cork tile floor is of recycled wood content and tree bark. No VOC building products are used. Local concrete plants were selected to provide cast-in-place and pre-cast concrete which constitutes more than 40% of the overall building material, thus reducing the environmental impact of the building and transportation costs.
Erosion and Sedimentation Control
The design team consulted the Connecticut Department of Environmental Protection, US Army Corp of Engineers and Inland Wetland Committee to develop an extensive erosion control/Plant dewatering strategy to prevent erosion.
Reduced Site Disturbance/Landscape
The design minimizes site disturbance by preserving existing wetland conditions and natural vegetation. The landscape design supports biodiversity and preserves natural habitats. The existing site wetland has been documented as a recess point for certain species of migrating birds; this important feature has been preserved and enhanced. Trees and bushes provide shading throughout. The majority of the plant species are native grass and low shrubs, which greatly reduce maintenance and irrigation costs.
Light Pollution Reduction
The design team demonstrated to the planning review board that due to the open nature of the landscape design, site lighting throughout the landscape was not required for security purposes. This reduces energy consumption and unnecessary off-site lighting.
Storm Water Management
The storm water drainage system is managed though landscaping as opposed to piping. The surface pond to the east of the project is designed as a catchment area for detaining storm water. While paved walkways and a plaza are part of the design, they have been minimized in lieu of a net decrease in the rate and quantity of storm water run off from the existing developed site.
Green Roof Design
The green roof increases the insulation R value by 3 points, prevents a heat island effect, and controls storm water runoff. The roof membrane is formed of a rubberized asphalt waterproofing system with an IRMA configuration. A root barrier fabric was installed on top of the insulation to optimize moisture management in the green cover and protect the insulation from water infiltration. The green roof is a low maintenance system and no lawn cutting or irrigation is required. Most of the plants will grow to about six-inches in height, and will spread to form full coverage within two growing seasons. The green roof design is expected to prolong the life of the roof membrane and protect it from normal wear and tear by buffering it from extreme freeze-thaw cycles and peak summer temperatures with possible abrupt cooling from rain-showers.
The planting plan was modeled after an alpine meadow and rock outcrop community. These ecological complexes thrive with shallow soils, exposure to wind, and pressure from some foot traffic, all without dependency on artificial irrigation or fertilization. This plant community will help to maintain an enjoyable condition for visitors, as well as those who view it from the overlooking park or nearby residences; but it will also serve as effective meadow habitat for birds, insects (notably butterflies) and small mammals. To achieve the sustainable, functional, and aesthetic objectives, the primary matrix of vegetation consists of various species of Sedum (S. sexangulare, S. floriferum, S. spurium alba, S. spurium fuldaglut, and S. album) planted inexpensively from 900 pounds of cuttings embedded across the entire roof. Roughly 7,000 flowering perennials were planted as plugs in drifts covering selected roof areas. These plantings such as Petrorhagia saxifaga Tradescantia bracheata, Dianthus deltoids, Sedum cauticola, and Campanula divericata, and others were chosen to provide year-round interest from blooms, foliage, height, and texture. This approach creates vegetation that offers fresh aromas typical of a mountain meadow.
Sliver: Induction Bent Steel Tube Hoops
Plant: Cast-in-place and pre-cast concrete
Exterior cladding: Metal/glass curtainwall (flush-glazed Low Iron IGUs on steel bar frame): A. Zahner, Kansas City
Concrete: Integrally colored Precast Concrete insulated panels by Coresla. Board formed cast-in-place concrete walls by GC
Metal roofing: Flat-lock stainless steel panels with angel hair finish: A. Zahner, Kansas City
Interior Finishes: acoustical plaster (ceilings), recycled glass aggregate terrazzo and cork tile and sheet linoleum(floor materials), exposed concrete, GWB,