Identifying adaptive flood risk mitigation strategies for San Francisco’s historic piers

Challenge:
The Port of San Francisco is committed to preserving its historic finger piers for future generations and recognizes that climate change and sea level rise threaten the vitality of its waterfront.

Solution:
Arcadis, Lotus Water and Incommon partnered with the Port of San Francisco to identify and assess the feasibility of several adaptive flood risk mitigation strategies that can be incorporated into near-term pier rehabilitation projects.

Impact:
When implemented, the floodproofing mitigation strategies provide the opportunity to protect 15+ piers, preserving more than 40 acres of valuable and unique waterfront space usable for decades.

Port of San Francisco” by SF.Port is licensed under CC BY-ND 2.0

Sea level rise threatens the vitality of San Francisco’s waterfront

The Port of San Francisco (the Port) is confidently confronting the dilemma facing America's coastal cities: preparing for sea level rise while protecting the vitality of iconic landmarks.

According to the California Ocean Protection Council, San Francisco’s bay tides are projected to rise at least three feet by 2100. The city’s waterfront is also becoming increasingly vulnerable to extreme weather events such as heavier rainstorms, heat waves and more severe flooding.

Averaging 80 to 100 years old, San Francisco’s piers are recognized as contributing elements to the Central Embarcadero Piers Historic District, symbolizing the piers’ role within the community. Over the past few decades, many of the piers have gained new life serving joint uses consistent with the Public Trust, such as maritime operations, public museums, eateries, commercial office space, distribution facilities, parking and other public-serving purposes, and several still have the potential to be redeveloped.

The Port is committed to maximizing the waterfront space while keeping the maritime function as intact as possible, and measures must be taken to preserve it for future generations.

“The Embarcadero’s historic finger piers are a part of our identity in San Francisco and it’s important to preserve these iconic structures for future generations,” said Elaine Forbes, executive director of the Port of San Francisco. “Partnering with Arcadis has allowed us to understand what we can do now to protect our waterfront from the impacts of climate change such as sea level rise.”

Investment in pier rehabilitation advances both the City of San Francisco and the Port’s resilience objectives to protect the value of the pier infrastructure and reduce seismic and flood risk. To prepare for future conversations with stakeholders, the Port began assessing the viability of waterfront redevelopment with respect to sea level rise.

Identifying adaptive flood risk mitigation strategies

The Port selected a team led by Arcadis to conduct an initial review of flood risk and provide potential floodproofing measures focused on the string of finger piers between the Ferry Building and Telegraph Hill and two unique piers near Oracle Ballpark.

Using current and projected flood risk data, the team identified five adaptive flood risk mitigation strategies and two supplemental measures. The supplemental measures target specific components of flood risk and pair with the adaptive mitigation strategies to improve the level of flood protection provided. For example, floating breakwaters primarily act to reduce the impact of waves to the water level and can provide additional flood protection support to the other strategies.

These adaptive measures are intended to protect the existing structures against flood risk over a substantial portion of this century, while minimizing the transformation of the structure itself, and therefore minimizing potential impacts to the historic district and limiting the capital costs needed to implement such measures.

Floating breakwaters
Deployable site protection
Dry floodproofing
Building interior elevation
Permanent site protection
Building systems protection
Wet floodproofing

Testing a range of scenarios is a critical step

To test the feasibility and technical suitability of the proposed measures, the team selected two piers at opposite ends of the northern San Francisco waterfront, Pier 19 and Pier 38, to demonstrate how the variation in structural condition and flood risk exposure affected the strategies. Two scenarios were considered for each pier:

  • Full rehabilitation: Intended to reflect a major financial investment in the piers to upgrade the substructure and superstructure to current seismic standards, thereby extending the life of the facilities.
  • Partial rehabilitation: Intended to signify the minimum investment necessary to implement the adaptive flood protection measures. 

The flood risk mitigation strategies were also evaluated from multiple perspectives, including: level of acceptance among the various stakeholders; engineering design considerations; depth of flooding above the pier deck the measure is able to protect against; constructability, permitting, maritime and below deck maintenance considerations; architectural or historic preservation and capital costs.

On the horizon

This initial assessment demonstrates the real possibility of preserving San Francisco’s historic piers while minimizing impact to the existing structures and location. The next phase of the study is to continue evaluating flood protection measures over a longer time period.

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