Built in 1966, the 1,971-ft-long (600.8-m) Ocean Beach Municipal Pier in San Diego is the longest concrete pier on the U.S. West Coast and the second-longest ocean pier in California.
Offering scenic views, abundant fishing opportunities, and a restaurant, it typically welcomes more than 500,000 visitors per year. But a recent report by civil engineering advisory firm Moffatt & Nichol (Long Beach, California, USA) suggests that the pier has suffered significant damage over the last 55 years and “has reached the end of its service life,” as presently constructed.
“Corrosion in the reinforcing steel has initiated, and the structure will continue to degrade unless corrective action is taken,” says the engineering report, which was completed in 2019 and released to media and the public in early 2021. “With the current condition of the pier and the magnitude of wave forces and potential seismic forces that the pier will be exposed to, severe damage or partial collapse of the pier is possible if the deterioration of the structure is allowed to continue,” the report continues.
Areas of the pier were inspected both above and below its exposure to water, and concrete cores were taken to a laboratory for analysis. During the inspection, areas of major deterioration on primary structural elements were observed, according to the report. Specifically, seven piles were found to have spalling, while 25% of piles were cracked. In addition, significant corrosion was found in the majority of pile caps and in the soffit of deck panels. Damaged piles and locations where deck panels are losing prestressing strands in the soffit are of particular concern.
“To ensure the continued use of the structure, deficiencies must be addressed,” the report reads. “Three options for remediation are repair of the structure, rehabilitation, and replacement. There are economic, environmental, and historical issues associated with each option.”
“While the initial cost of the repair option is less, the repairs will not address the continuing deterioration of the pier, and the cost to keep the pier operational going forward will be significant. Rehabilitation will increase the service life of the structure, but the cost is comparable to the replacement option and will change the aesthetics of the structure with the addition of large pile jackets. It will also result in extending the service life, but for a shorter amount of time than possible with the replacement. Replacement of the structure will allow the City to design the pier for current seismic codes and address sea-level rise to ensure the pier will be available for generations to come.”
According to the report, the pros and cons of each route are as follows:
“The rough order of magnitude (ROM) cost for repairing the existing damage to the pier and placing galvanic anodes to mitigate additional corrosion is estimated to be $8 million,” the report finds. “This repair program could be tailored to address the most egregious locations first and then continue an inspection/repair cycle going forward, if the funding needed to be distributed. There are also additional costs for mobilizing a marine contractor for multiple repair cycles.”
“If the repair option is chosen, the structure will continue to degrade, and the repair cost will escalate with time. There will be additional costs for the continued inspections every three y, repair design, and subsequent repairs. For example, the seven piles that need to be jacketed currently were cracks a decade ago. This implies that there will be dozens of piles requiring jackets in the next 10 years. This represents significant capital investment and additional closures of the facility for repair activities. Additionally, the pier will continue to need to be closed in large storm events and is at greater risk in a seismic event. Over the 50-y life, this would be the least cost-effective option.”
“The rehabilitation option would increase the service life of the structure but would not address the sea-level rise vulnerability,” the report finds. “The ROM for the rehabilitation option is $30 million to $50 million. If environmental constraints make the replacement option unfeasible, rehabilitation is the most cost-effective solution.”
“The replacement option could be designed for a 50-to-75-y service life,” the report says. “Replacement would also allow for the accommodation of sea-level rise, design for improved seismic performance, and provide a reduction in the time the pier will be closed due to large wave events. While this path forward includes the largest initial capital expenditure, it will likely be the most cost effective over the next 50 y. The ROM for the replacement option is $40 million to $60 million.”
As of the summer of 2021, local officials had yet to determine a long-term choice for the Ocean Beach Pier. “Significant investment in a repair program would need to be well funded and sustained, as the structure will continue to exhibit significant deterioration in the near term,” the engineering report concludes.
“The rehabilitation option and replace option, while both are large endeavors requiring capital investments and pier closures, would be a better long-term solution to keeping the pier operational. The replacement of the pier would be the recommended choice, as the structure could be designed efficiently to resist seismic events, and the threat of sea-level rise can be addressed.”
In early 2021, the pier was closed entirely after high surf caused railing boards to break. However, after conducting a series of localized repairs, parts of the pier reopened to the public in late May, with restrictions. These restrictions include a closed expansion joint; no vehicular traffic except for emergency vehicles, as needed; and automatic closures during periods of very high tides.
According to a press release from the Ocean Beach MainStreet Association nonprofit, future construction of the pier “will likely include modern materials at higher elevations, to withstand potential sea level rise and the effects of climate change.” Meetings will be held involving local leaders and community groups to ensure that future proposals are aligned with community interests.
“I am grateful that a large portion of the pier can be safely reopened for the enjoyment of residents and visitors,” says Jennifer Campbell, president of District 2 for the San Diego City Council, which represents Ocean Beach. “Much more work will need to be done to address the damage to other parts of the pier and find a long-term solution moving forward. The Ocean Beach Pier is a treasure to our community and has served the city for over 50 years, and I am determined to look at all options with members of this community to plot out what the next 50 years will look like.”
Source: Ocean Beach MainStreet Association, www.oceanbeachsandiego.com/attractions/ocean-beach-pier.