The City of Phoenix was ranked as the “Best Run City in the World” in 1993 by the Carl Bertelsmann Foundation. It is also the only city among the nation’s 35 largest urban centers to earn an overall grade of “A” from the Maxwell School of Citizenship and Public Affairs at Syracuse University in 2000. Not content to rest on past laurels and always ready to embrace innovation, Phoenix is now determined to take a leadership role in the water treatment industry, as evidenced by the design-build-operate (DBO) delivery of the new Lake Pleasant Water Treatment Plant (WTP) that will feature an array of advanced technologies.
Currently the largest DBO potable water project in North America, the first phase of the Lake Pleasant WTP will deliver the highest quality, state-of-the-art drinking water to 400,000 households. The project stands out, not only for its scope and delivery method, but also, because the All American Water Team (AAWT) maintained the project schedule, within a fixed budget, while facing significant challenges, such as escalating materials costs and substantial labor shortages in the Phoenix area. Change orders were few during a 42-month design, permitting, and construction schedule. Construction started two months ahead of schedule as a result of phased permitting, resulting in a budget reduction of nearly $30 million for the City.
Explosive Growth, Increased Water Demands
The City of Phoenix (City), like many western cities, has experienced explosive growth in the past 50 years, with its population expanding from 100,000 in 1950 to more than 1.4 million residents today. The rapid increase in the population (fifth largest US city) and expansion of city boundaries, combined with progressively more stringent potable water regulations, created a major challenge for the City to provide reliable, high-quality, drinking water to consumers. To tackle this challenge, the City began in the late 1990s to evaluate various conceptual designs and delivery methods for a new water treatment facility that would serve the increasing number of consumers in the North Phoenix area and meet the standards of the prevailing and future anticipated drinking water regulations.
The end result is the Lake Pleasant WTP, with an initial treatment capacity of 80 mgd, expandable in 80 mgd increments to an ultimate capacity of 320 mgd. The current Phase 1 project comprises a raw water intake on the Central Arizona Project’s (CAP) Waddell Canal, sized to handle the ultimate 320 mgd plant capacity, a raw water pumping station, approximately two miles of 90-inch raw water transmission line, a multi-barrier treatment process train, on-site residuals treatment, and handling facilities, two 20-million-gallon buried reservoirs, a finished water pumping station, a 69 kVA substation, various chemical buildings, and an operations center.
After completing and evaluating a siting study, the new facility was located in the northwest valley near Lake Pleasant and the Waddell Canal. The City then began to consider various options for completing design and construction. The goal was to target options that offered fast delivery, low total ‘whole life’ costs, reduced litigation risk during project delivery, and maximized technical innovation, without reducing reliability.
Alternative Delivery Methods Evaluated
The City assembled a multi-disciplinary team of City staff and consultants to investigate alternative delivery methods. The team solicited opinions from contractors, consultants, manufacturers, citizens, and officials on which delivery methods to investigate in more depth. Initial reaction was to proceed with the project using a traditional design-bid-build philosophy, as alternative delivery methods on other water treatment facilities in the US had met with mixed success. However, further review and discussion indicated that the traditional approach was perceived as costly and conservative, with higher risks, and not able to capitalize on advantages realized with other alternative project delivery methods.
The City team decided to complete additional research on the various delivery methods with the goal of determining which should be investigated in further detail. After compiling the results of its surveys and research, the team selected four delivery approaches for more detailed review. These included:
- Traditional design-bid-build (DBB) with City personnel operating the plant (Benchmark),
- Design-build with City personnel operating the plant (DB),
- Design-build-operate with a third party operating the plant (DBO), and
- Purchase water from a privately-owned facility (Merchant Plant).
In the ensuing evaluation, the study team considered process elements, risks, level of City control, schedule, market availability and interest, permitting strategies, quality and reliability of delivered water, cost, and financing options. It was at this point that the City developed a benchmark design and costing using the traditional DBB approach to determine what cost-savings could potentially be realized utilizing the DBO method of delivery.
DBO Approach Selected
The City team eventually concluded that the DBO approach was most appropriate as it met all of the City’s goals for the project, it:
- Allowed construction to begin during the design and permitting phase, resulting in a faster delivery process.
- Projected approximately 10 to 15 percent savings over traditional project delivery methods.
- Maximized the number of perspectives and the experience base of companies involved in the layout and design of the facility, thereby maximizing the potential for innovation and “out-of-the-box” thinking.
- Significantly reduced the risk profile of the City during project delivery.
Of particular interest to the City was that DBO takes advantage of a team philosophy throughout design, permitting, construction, and into operations. This would result in a design that utilized the combined experience of the City’s Water Services Department Engineering and Operations staff, along with the DBO team’s design, construction, and operations personnel to minimize both capital and long-term operating costs and maximize design efficiency, constructability, and an “operator-friendly” approach to planning the plant. Additionally, having the operator involved throughout ensured that care was taken during all phases of construction to provide facilities with a long service life and minimized short- and long-term maintenance requirements.
In selecting this delivery method, the Arizona State Legislation required legislative refinement to allow for alternative project delivery methods. This was followed by a financial and technical prequalification stage and a lengthy, 18-month, three-phase procurement process, which culminated when the City received three technical and cost proposals in November 2002. The proposals were evaluated and ranked by the City and its advisors for technical, financial, and commercial/legal content. This ranking, combined with scores for both technical content and overall costs (capital and operating and maintenance), allowed the City to rank proposals and select a successful respondent. The AAWT was awarded the $336 million contract in June 2003.
The All American Water Team
The AAWT is comprised of American Water Services, Inc., as the prime contractor and operator; the American Water Works Company as project guarantor; and Black & Veatch Corporation/McCarthy Building Companies, Inc., in joint venture for the DB portion of work. Major subcontractors to DB team included Ames (earthwork); University Mechanical, Inc.; and Ludvik Electric, Inc.
Technical Innovation
The service agreement requires the production of water that meets all requirements of the Safe Drinking Water Act (SDWA) plus some foreseeable future regulations. The agreement includes performance standards more stringent than the SDWA requirements for such parameters as alkalinity, aluminum, arsenic, bromate, calcium carbonate saturation index, biodegradable organic carbon, chlorine, total coliform organisms, true color, Cryptosporidium and Giardia, fluoride, geosmin and e-methyl isoborneol, trihalomethanes and haloacetic acids, iron and manganese, and turbidity. Upon award of the contract, the AWWT began preparing to deliver water to the City’s distribution in early 2007.
The technical challenge was to develop a treatment process that would achieve the City’s enhanced water quality goals, meet its quality standards for treatment facilities and be designed, permitted, constructed, and commissioned, plus pass rigorous acceptance tests, in under 42 months. To accomplish this, collaborative efforts commenced in 2001, during the procurement phase. Process experts from Black & Veatch and American Water developed treatment alternatives that, in turn, were reviewed and evaluated by McCarthy for cost and constructability, and by American Water for reliability, ease of operation, and operating costs projected over the 15-year operations contract period.
This collaborative approach continued during the capital project delivery phase where the AAWT has, with the City and its consultant joined in a formal ‘partnering’ approach for all phases, to allow early and amicable issue resolution.
A Facility $30 Million Under the City’s Benchmark
The AAWT developed a project schedule that included design, internal operational and construction reviews, City reviews, permitting (over 50 different permits from federal, state, and municipal entities), procurement, construction, start-up, commissioning, and acceptance testing. This resulted in the facility being divided into six distinct areas so design and permitting could be staged to optimize construction, minimize cost, and satisfy regulatory authorities. This staged design and permitting schedule also allowed the construction to begin two months prior to the projected start date in the service agreement.
The Lake Pleasant WTP has a robust process design that employs multiple barriers for maximum operational flexibility and treatment of varying raw water qualities. The treatment includes a complement of processes in the US not typically brought together in one facility. The process configuration takes advantage of the team’s multiple perspectives on current technologies and reduces the size and complexity of construction. It also afforded a plant layout that minimizes impacts on the native desert environment that was one of the service agreement requirements. Some highlights of the design include the following:
- Site layout was configured to minimize impacts on native washes and indigenous plant life, reducing permitting requirements and the consumption of open space, while allowing for future expansions. The landscaping and architecture was designed to match the natural environment, consistent with the Frank Lloyd Wright architectural philosophy. Extensive use of indigenous materials and native plants in the landscape design links the worlds of nature and man, and demonstrates the interdependence of the architecture with the finished site.
- Ballasted flocculation was selected for primary pretreatment because the high-rate process is robust, able to handle a wide variation in raw water influent quality, and requires a significantly smaller footprint than traditional sedimentation basins.
- Deep bed anthracite filters and granular activated carbon (GAC) contactors were combined in series to ensure maximum turbidity reduction and removal of naturally-occurring organic matter prior to disinfection.
- Ozone and ultraviolet radiation were included to add additional barriers to pathogenic compounds and reduce the chlorine disinfection demand, thus reducing the risk to the operations staff from large amounts of chlorine storage.
- Solids-thickening and dewatering is included via centrifuges for on-site solids separation. Plant solids are transported off-site for ultimate disposal.
- GAC regeneration facility provides on-site carbon regeneration capabilities and an option for regeneration of activated carbon from other water treatment facilities in the area.
- The inclusion of this level of multiple-barrier process technology will allow the operator flexibility for developing optimum treatment strategies for maximum control of multiple parameters. For example, if removal of natural organic matter is optimized in the ballasted flocculation and ozone/biofiltration processes, organic loading on the GAC contactors will be reduced, and GAC will require replacement less frequently. On the other hand, if the water periodically contains high bromide levels, ozone may require reduction or be turned off; in which case, GAC would provide primary control for taste and odor compounds.
With the Lake Pleasant WTP nearing completion, functional testing and commissioning commenced in the fall of 2006, with acceptance tests scheduled for January 2007, at which time finished water will be delivered to the City system. When final completion is achieved in early 2007, a 15-year plus five-year option, operations and maintenance contract will commence.
In summary, the Lake Pleasant WTP provides state-of-the-art water treatment and residuals handling facilities that were designed with extreme flexibility, using many different treatment strategies. The resulting operational flexibility will allow the facility to meet all of its water quality goals regardless of the incoming water quality. DBO delivery has been successful in Phoenix, primarily due to the commitment of all parties to work together. In applying this partnering approach on a fixed price DBO, the outcome has been successful for all the stakeholders.
INFO: City of Phoenix (www.phoenix.gov)