Sept. 10, 2019
Reduce risk and shorten recovery time by identifying and prioritizing systemwide improvements

HISTORICALLY, MASTER PLANNING for water distribution systems, sanitary sewer collection systems, and treatment plants has focused on three main factors: growth and capacity, standards and regulations, and, in the past ten years, the condition of their assets. While these factors give utilities an effective strategy for understanding which future projects they need given the factors’ projections, utilities typically do not consider how a catastrophic event, such as a natural disaster or act of terrorism, would affect the system. This is why critical service providers have increasingly considered a fourth factor in their decision-making and planning efforts: resiliency.

Infrastructure in the United States—especially water and wastewater systems—is rapidly aging and growing more insecure. At the same time, the frequency of catastrophic events, and our understanding of them, is rapidly evolving. To prepare for an event that could leave a water or wastewater utility unable to perform its basic or critical services, resiliency-based planning must be considered to reduce damages to critical infrastructure and help utilities concentrate their efforts and resources on less critical areas.

As defined by the Department of Homeland Security (DHS), infrastructure resilience is:

The ability to reduce the magnitude and/or duration of disruptive events. The effectiveness of a resilient infrastructure or enterprise depends upon its ability to anticipate, absorb, adapt to, and/or rapidly recover from a potentially disruptive event.1

As cities, counties, and districts update their master plans, resiliency-based planning is becoming a higher priority than ever before. Notably, the state of Oregon has taken the initiative to develop a specific resilience plan for its utilities. In 2011, Oregon adopted House Resolution 3, which directed the Oregon Seismic Safety Policy Advisory Commission to lead and coordinate the preparation of a new resilience plan.

Published in 2013, the Oregon Resilience Plan summarizes the science of Cascadia subduction zone earthquakes and tsunamis and estimates their impacts. Additionally, it provides detailed analyses of the existing vulnerabilities within buildings, business communities, transportation, energy, communication, and water/wastewater systems. The Plan also defines the performance targets that each sector must meet to achieve adequate resilience and offers detailed recommendations for the actions required to meet those targets over the next 50 years.

To supplement the water and wastewater elements in this plan, the Oregon Health Authority (OHA) has recently required water systems with 300 or more service connections to include a seismic risk assessment and mitigation plan with five-year updates to water system master plans, per OAR 333-061-0060. Soon, other states will also enforce such requirements for their water utilities.

On a national level, Section 1433 in America’s Water Infrastructure Act (AWIA) of 2018 updated the 2002 Bioterrorism Act. Section 1433 now requires utilities to provide letters to the Environmental Protective Agency (EPA) stating that they have conducted, reviewed, or revised, as applicable, their Risk and Resilience Assessment and an Emergency Response Plan. The utility is required to assess the following:

  • The risk to the system from malevolent acts and natural hazards.
  • The resilience of the pipes and constructed conveyances, physical barriers, source water, water collection and intake, pretreatment, treatment, storage and distribution facilities, and electronic, computer, or other automated systems (including the security of such systems) used by the system.
  • The system’s monitoring practices.
  • The system’s financial infrastructure.
  • The system’s use, storage, or handling of various chemicals.
  • The operation and maintenance of the system.
  • Possibly, an evaluation of capital and operational needs for the system’s risk and resilience management.

The deadlines for these letters vary depending on the size of the utility, but range from March 31, 2020, to December 30, 2021, and must be recertified every five years. Although this new requirement is only for water utilities, the importance of resiliency-based planning for utilities is clearly strengthening, and other types of utilities are expected to follow the same path.

When first planning for resiliency, the plan typically identifies hazard scenarios that allow the utility to assess its facilities for multiple hazards during document reviews and site visits. The resilience plan also identifies any geotechnical improvements or facility relocation due to seismic hazards from soil liquefaction, lateral spreading, landslides, and ground shaking. In turn, these evaluations benefit a master plan by providing valuable information for where to place capacity-driven structures or collection systems.

A resiliency plan is important for master planning because it helps identify and prioritize system-wide improvements needed to increase the system’s resiliency, reduce risk, and shorten recovery time. For instance, water services for fire suppression, first aid, and emergency response are required during or immediately after a catastrophic event; meanwhile, wastewater systems must protect the community from sewage contamination, health hazards, and disease outbreaks within the first 24 hours. With these needs in mind, a resilience plan prioritizes projects that will reduce the recovery time for the associated risks.

The projects identified in the resilience plan ultimately complement the utility’s long-term capital improvement program (CIP) from its master plan. For example, a wastewater system’s master plan might recommend increasing capacity by adding another clarifier to its treatment plant. Normally, the clarifier would be constructed using typical structural codes. However, because the utility has evaluated its existing clarifiers against resiliency-based performance levels, it would be in its best interest to construct the new clarifier to those same levels. This type of planning can benefit the utility from a similar viewpoint: if the resilience plan recommends a structure to be retrofitted but that structure is not as critical immediately after a seismic event, the utility might delay the retrofit and instead incorporate the resiliency recommendations when the structure is replaced.

The previously mentioned ORP and the National Institute of Standards and Technology’s (NIST) Community Resilience Planning Guide provide a framework for target recovery times unique to elements of water and wastewater systems. This framework also prioritizes these elements, beginning with water supplies and the “backbone” of the system (infrastructure that supplies critical customers), followed by fire flow and infrastructure that serve emergency supply points. Eventually, the entire system would be restored.

Looking ahead into the 21st century, utilities in the United States must aggressively incorporate resiliency into their water and wastewater systems to defend public health, economic activity, and the environment after any catastrophic event. Utilities everywhere are encouraged to incorporate resiliency-based projects into their planning efforts to continue providing reliable service during and after a catastrophic event.


1. Critical Infrastructure Resilience Final Report, Department of Homeland Security National Infrastructure Advisory Council, September 2009.

About the Author

Lara Kammereck

Lara Kammereck, P.E., is a senior project manager and vice president at Carollo Engineers. A municipal planning specialist with more than 25 years of experience in the field, she assists water and wastewater clients in developing resiliency assessments, comprehensive plans, alternative analyses, and condition assessment evaluations    

About the Author

Kevin Tice

Kevin Tice, P.E., is a utility analyst with Carollo. His experience includes managing water and wastewater master planning projects, developing Level 4 cost estimates for capital improvement programs (CIP), and analyzing the impact of CIPs on utilities’ financial forecasts.

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