Posted on Wednesday, April 25, 2018
Owners often assume that they will have to sacrifice one of their ideals – high quality, fast schedule or lower cost - in pursuit of the other two. But within a well-executed design-build-operate project, that doesn’t have to be the case.
A good example was the d-b-o of the Jasper wastewater treatment plant: the first application of concentric-ring digestors for biological nutrient removal in western Canada. The $11 million project was completed within 9 months from concept-to-commissioning and treats the Municipality’s effluent prior to discharge in the heart of the Canadian Rockies. As the project director at Earth Tech, Bill Berzins was lucky enough to work with some of Canada’s top d-b-o practitioners (Gerry Stevens, Rick Bitcon, John Haanstra and Warren Wilson to name just a few) who collectively achieved the client’s “trifecta” with an award winning plant. After biological nutrient removal, an ultraviolet system disinfects the effluent prior to its discharge into the exfiltration system. After the treated effluent enters the exfiltration basin, some of the water is lost through evaporation or taken up by plants with the rest percolating out into the wetlands alongside the Athabasca River.
The Municipality’s original EPC had estimated a capital cost of >$15 million with a project duration of >1 year: however the d-b-o team from Earth Tech beat both targets easily. The key to these gains was an innovative design that originated from a highly collaborative project team.
In a traditional WWTP design, rectangular digestors require complex rebar and formwork geometry that adds considerably to the cost of materials and construction duration. Early on in the design, John challenged the team to consider a much simpler geometry: nested concentric rings with annular flow through aerobic and anoxic zones instead of daisy-chained rectangular chambers. John argued that the concentric ring digester utilized the hoop-strength of cylindrical configuration and eliminated complex corner geometry. In addition, the equalization of hydrostatic pressures between the inner and outer rings reduced the quantity of rebar and concrete required for the innermost vessel.
It didn’t take long for the team to realize that the gains out-weighed the risk and generated a significant savings in time and money. Working within tight time constraints and the onset of winter, Gerry, Rick and Warren literally (and figuratively) thought outside the box and found a way to make the concentric ring configuration work under a variety of water quality scenarios. To top it off, Gerry had to commit to a fixed-price long-term operating contract on the basis of a brand-new design concept. With buy-in from all corners, the final concept progressed quickly through design and into construction, with an award-wining result.
So budget and schedule benefited, but what about quality? As expected, improved quality was a natural outcome. With a significant reduction in rebar and concrete, more funds were made available for upgraded UV sterilization and improved instrumentation and controls. A faster and more economical project actually reduced the project’s environmental impact and reduced the risk of upset conditions.
Of course, these successes required a contract structure and level of client sophistication that supported the innovation. Keith Shepherd (Municipality) and Jonathan Huggett (p3 practitioner) worked collaboratively with the d-b-o project team to establish a project charter, contract framework and set of expectations that allowed the project to move quickly through design, procurement, construction and commissioning. From a shared-commitment to the triple bottom line, a highly-successful project emerged and continues to set a high standard for effluent treatment even to this day.
Over our careers, we’ve learned that successful d-b-o’s emerge from the application of a high level of expertise/experience within a coherent and cohesive strategy. As you navigate through our site content, you’ll find more examples of how d-b-o can achieve the project trifecta.