Optimization and Sustainability Can Reduce Costs

The Challenge

When it comes to justifying design optimization, sustainability is still, for many, not a good enough reason to go through that process. Financial benefits, on the other hand, are seldom ignored, and thus when cost savings can be demonstrated the alternative design is almost certainly going to be accepted. But what is often ignored is that such an optimized design may very well be, and in most cases is, more sustainable, because more often than not design optimizations not only reduce cost, but also involve fewer materials and thus are more sustainable.

The Example

For many years DFI has presented the IT$ Money webinars, where every other month three case studies are presented to demonstrate that Increased Testing $aves Money. The original idea behind this series came from Van Komurka, P.E., D.GE, GRL Engineers, and in February of 2020 he presented a case study where the design was optimized by performing preconstruction bi-directional load testing. The project was the design and construction of two bridges over the Clark Fork River in Missoula, Montana, where the original design called for eight 71 in (1,800 mm) diameter shafts to a depth of 65 ft (17 m). By conducting the preconstruction load testing the shaft lengths were reduced by 16 ft (5 m), which saved some 130 cu yd (100 m3) of concrete. This design optimization was deemed a great success: even after accounting for the testing cost, some $25,000 were saved and the construction schedule was reduced by four days.

The Added Benefit: More Sustainable

As the design optimization was lauded because of the economics, very little thought, if any at all, was given to the idea that this was also a more sustainable design. But it is. While the numbers may not be spectacular, the reduction in length for those eight shafts eliminated some 91,000 lb (41,000 kg) of CO2 emissions based on the reduction in concrete volume alone. The total emissions reduction was more than that given the reduction in the amount of reinforcement steel, which was not addressed in the presentation and therefore not included in this column. But even based on the reduced concrete volume, the reduction in emissions would more than offset the emissions generated by driving an average gasoline-powered passenger car for 106,000 mi (170,000 km) or by annual electricity use of eight homes (based on the EPA Greenhouse Gas Equivalency Calculator).

It simply reinforces the message Seth Pearlman, CEO North America and board director at Menard, gave during the DFI Sustainability webinar last year, when he stated that in the foundation industry “sustainability really means…designs using fewer materials and resources to produce.” That kind of optimized design saves money and is more sustainable. So, it simply makes sense to take that extra step on every project.