After evaluating the proposals and interviewing both firms, Public Services awarded the project to the lower of the two pre-qualified bidders: CDM Smith. The firm was to integrate the existing lime-softening electrical system into the new facility while maintaining complete operational service during construction.
Had the department awarded the project via design-bid-build, the project would've taken 178 weeks to move from 30% design to completion. Design-build shaved 74 weeks — a 42% reduction — from the process. The project, including migrating the existing lime-softening electrical system to the new facility, was completed within 24 months of contract award.LEED-certifying an energy-intensive process
Public Services and CDM Smith used the student designs to fully develop the plant concepts, including their ideas for LEED certification, a voluntary system that encourages architects and engineers to design and build more energy efficiently. The program evaluates projects in five categories.
1. Sustainable Sites. LEED wants applicants to use using existing disturbed sites as opposed to virgin sites and increase green space on the site. Dania Beach's new nanofiltration facility is on the same site as the current lime softening plant, which is refurbished and available to supplement the nano-filtered water.
The design increases the volume of pervious surface by reducing the amount of asphalt on the premises, using pervious pavement, and removing unused structures. To encourage employees to use alternative transportation, parking spaces are provided for carpoolers and those who drive alternative fuel vehicles. A bus stop is located at the site boundary. Showers and a bike rack also were added.
2. Water Efficiency. The building expects to use half the water of a similar structure, roughly 100,000 gallons annually; treatment process improvements are expected to save an additional 36 million gallons annually.
The new treatment process recovers a minimum 90% water, more than most membrane systems. When running at 95% recovery, the plant is 10% more efficient.
The city altered an ordinance to preclude the need to irrigate when Florida-friendly species are planted, and rain is being captured and stored to irrigate the rest. In addition, the administrative space has low-flow toilet fixtures, waterless urinals, and low-flow faucets and showerheads.
3. Energy & Atmosphere. By definition, nanofiltration would increase power needs. To compensate, our goal was to reduce energy use by 30% over a similar building while deploying energy-saving treatment technology.
White roofs lower attic temperatures by 30° F; insulation keeps cooled air inside. A high-SEER (seasonal energy-efficiency ratio) HVAC system automatically adjusts temperature depending on internal conditions and occupancy as well as external temperature. To lower lighting costs, almost all of the building — 95% — receives sunlight. Lights that weren't eliminated were changed to compact fluorescent bulbs and automatically turn on and off. Combined, these changes are expected to reduce interior electricity use by 2 kW hours/day.
On the treatment side of the equation, variable-frequency drives, efficient motors, and controls counter nanofiltration's energy requirements. The system operates at 100 psi, well below the 120 to 150 psi that similar facilities require.
The city also buys green power credits from the Carbon Solutions Group.
4. Materials & Resources. The contractor recovered and recycled 95% of asphalt, concrete, and steel and bought additional recycled material from sources within 500 miles. This reduced transportation costs, earning two points toward certification.
5. Indoor Environmental Air Quality. Since the goal here is to reduce air pollution, smoking is prohibited in both offices and the treatment plant.
In addition, the operator workspace was built using no VOC materials, paints, and finishes; low-VOC materials were used on the rugs, floor glue, paint, and cabinetry.
The facility has won a U.S. EPA award for sustainable infrastructure and a Florida Institute of Consulting Engineers design award.
— Bloetscher (h2o_man@bellsouth. net) is associate professor in Florida Atlantic University's College of Engineering and Computer Science and president of Public Utility Management and Planning Services Inc.