Service Life Estimation for Waterfront Repairs and Rehabilitation

Abstract: A waterfront facility assessment is an asset management tool for owners and stakeholders to help them understand the existing condition of a waterfront structure, what repairs may be required to maintain operations, maintenance considerations, current operational restrictions (if applicable), and what the estimated remaining service life of a structure is. For routine-level inspections, the estimate of remaining service life is based on the assessing engineer’s experience and judgment. The service life estimation is a vital component of a waterfront facility assessment as it plays an important role in continued operations, planning, and budgetary programming. However, these estimates can be subjective due to representative data and engineering judgement used to determine them.
The ASCE Waterfront Facility Assessment Manual defines service life as “the length of time a structure or facility may be used economically before emergent damage or deterioration causes increasing interruptions in facility operations or a threat to public safety.” The term “used economically” generally refers to the point in time that the cost of repairs exceeds the cost of replacement. Consequently, the repair type, repair costs, and repair durability have a significantly impact on the actual remaining service life of a structure, especially during the later years of its use.
The predicted design life of various structures and material types is fairly well documented and can be further validated through material testing and life-cycle modeling. This same data and technology can be applied for some in-service structures, taking into account different factors such as exposure and use. However, this information and modeling is generally based on unrepaired structures. The durability of repairs is much more difficult to determine, as it can vary significantly depending on design approach, repair methodology, quality of work, and material interfaces. Additionally, the industry data on repair durability is not as well documented, with repairs often resulting in recuring repairs or increased cyclical maintenance. For example, there are several repair approaches for timber piles including posting, wraps, and jackets, each offering a different level of protection, performance, and intended longevity.
This paper evaluates over 20 waterfront facilities located throughout New England, assessing structure maintenance and repair projects that have been completed over a period of more than 30 years, and the corresponding condition ratings. These facilities include structures of various construction types and materials, which have undergone several cycles of repairs and rehabilitation. Construction cost data for different repair types is included, adjusted for inflation rates to provide unit baseline costs. The result compares the baseline costs of various repair types used on these structures and approximately how long the repairs last before recurrent repairs were required, or load restrictions implemented. This information can be used as a tool when performing service life estimates, incorporating repair durability and cost data, to better predict the point where structures can no longer be used economically, effectively ending their useful service life. More accurate service life predictions will allow stakeholders and owners to make more informed decisions for their facilities, especially for repair prioritization and budgetary programming.

How does this project / topic contribute to the advancement of the industry and profession?: Estimating service life of structures is an important part of waterfront facility assessment. However, there is little data on service life of repairs. This paper uses case studies to provide data on cost and durability of waterfront structure repairs, and how it impacts the overall service life of the structure.

Does the project / topic implement new and innovative techniques, materials, technologies, and delivery methods?: The project includes discussion and evaluation of new repair technologies and how their durability compares to past repair approaches.

What was the most challenging aspect of your project / topic and how did you handle it to ensure success?: The topic is not a specific project; however, the most challenging aspect was gathering and reviewing the large amounts of archive data, validating the data, and assessing it to develop clear and understandable results.

Who is the target audience for this paper?: Engineers, owners and stakeholders.