development surface water runoff. Over the course of several hundred acres, a slight deviation in slope or stormwater infiltration rate can have enormous impacts on surface water management. Perimeter and interior access roads also often cause challenges. It may seem simple, but the project team should agree on the width of the roads early on – critical for equipment to clean panels in arid conditions and maintain vegetative growth in other conditions. Likewise, the project team should agree early on the required surface of the roads – whether they are gravel or native soils, for example. Within the context of meet - ing the seemingly more complex power generation requirements for substantial completion, site grading, maintenance, and operations can evolve into an expensive afterthought. Like all construction projects, cohesiveness between owner-provided documents and contractor-generated documents helps ensure mutually acceptable final conditions and payment. An owner should expect a contractor to rely on owner-provided geotechnical reports and bor- ing reports. These are valuable documents but limited by their innate sample-sizing. Rock, structurally inadequate soils, high groundwater, and existing infrastructure are not uncommon to incur during foundation and pile installation. Like retroactive grading after substantial completion, The request for long-term concrete structures without premature need for maintenance and repairs is growing rapidly all over the world. Clients have asked for structures, tunnels, or bridges to be designed to satisfy a specified service life, usually around 100 years and sometimes even 200 years. This surpasses the design life of traditionally used codes and standards. Usually, the durability is ensured by adopting rules and standards such as Eurocode, AASHTO LRDF, BS, or DIN. Unfortunately, these rules that are based on experience and research have many faults and can very often result in durability design that is not adequate. Codes and standards that we use today are too often insufficient, and we cannot rely just on those standards. The term ‘du- rability’ started being considered just as important as ‘structural safety’ about 40 years ago. Engineers, contractors, and owners had to learn Achieving Sustainability by Utilizing Migratory Corrosion Inhibitor Technology
retrofitting or remediating inadequate foundations and piles late in the project can be very expensive. Owners and EPC contractors must have fair contractual mechanisms, like differing site conditions or changes clauses, to equitably address the unforeseen and to progress with the project. In Closing Due to the unique characteristics of solar power generation facili- ties, along with the rapid improvements in technology and speed of construction, solar is attractive in many areas with favorable condi - tions. This includes both fast developing countries and the United States. Aside from innate climate characteristics such as cloudy or rainy days, solar offers a predictable output of power that benefits investors, owners, users and ultimately spurs economic growth. The coming years will further prove out solar power’s immense benefits and capabilities, so long as the industry mitigates the risks inherent with the anticipated growth. GENE F. RASH AND STEVEN J. STUART are partners with Smith Currie & Hancock, LLP, a leading nationally ranked construction law firm. Their practices include contract drafting and litigating large-scale utility and infrastructure projects throughout the United States and abroad. They can be reached at gfrash@smithcurrie.com and sjstuart@smithcurrie.com, respectively. Learn more: www.smithcurrie.com. more about the fact that environmental impacts are irreversible and they worsen with time. This happens, for example, because of the ac - cumulation of chloride ions in concrete exposed to salts or sea water. How to approach durability design? Most standards as well as design codes for concrete structures have a “wish-to-satisfy” approach to the design and specification of reinforced concrete in various exposure environments, including exposure to chlorides. Design life has not been included as a consideration except the obvious time-dependent nature of the risk of concrete deterioration such as reinforcement corrosion. Today, design for the durability of new reinforced concrete structures is based on a prescriptive approach. Environmental impacts are characterized in exposure classes in EN 206 and the resistance of the structure to these impacts is defined by a set of requirements, e.g., concrete strength class, w/c ratio, cement content cover depth, crack width needed to achieve the required ser- vice life without major repair work (for bridges, usually 100 years). The design, construction, and planned maintenance of a concrete structure have to lead to the intended level of safety and serviceabil - ity throughout its entire service life. It is very important for designers to understand the basic deterioration mechanisms and the potential types and rates of damage development. For example, different types of corrosion cause very different damage developments, some of which reduce structural safety.
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November 2021 csengineermag.com
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