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Staying Ahead of Mother Nature in your Design Basis

Staying Ahead of Mother Nature in your Design Basis

A shifting climate has created increased concerns for utilities and power infrastructure: hundred-year storms are now commonplace, Texas has experienced a record freeze, and hurricanes are becoming more destructive. These events are impacting our system in ways we never thought possible. Appropriately protecting your investment (and future budgets) from risk can be hard to do. But how can you learn to expect the unexpected?

Here are six unseen risks created by climate change and outdated design standards, and what you can do to combat them:

1. Flood plains and shorelines are shifting.

FEMA maps do not always accurately capture flood risk and the impacts of climate change are changing floodplains and shorelines more rapidly than ever. These maps are often only updated when a project requires it, so it’s possible a stream has since changed course, undercutting current transmission line structures or putting substations at risk of flooding in the next extreme weather event. Valuable assets can be severely damaged by rising water levels and, when sites are flooded, cause difficulty when accessing sites and performing maintenance, driving increased safety concerns.

Black & Veatch has witnessed several projects relocate transmission poles and raise breakers, breaker cabinets and control buildings because of flooding issues at sites where the flood plain or water way changed paths since construction. We even modified a project during construction when a substation site experienced unexpected flooding.

Having a standard approach for reviewing existing assets’ flood risk helps to prioritize upgrade projects. Since a consistent design basis for constructing new assets is only as good as what it’s based upon, it’s critical to consult hydrology experts on appropriate design basis and margins to future-proof your assets. Critical assets close to coasts and waterways should consider a hydrology study and coastal terrain mapping that includes climate change modeling.

Flood plains and shorelines are shifting

2. Ambient temperatures are changing.

Sustained temperature changes outside the designed temperature can have a significant effect on equipment operation and performance, as equipment and materials are rated based on the environment where they operate. For example, when temperatures exceed norms, new risks emerge – equipment can overheat, requiring curtailment, additional cooling measures, or removal from service at a time when the equipment is most needed to support system load flow.

Let’s consider tank heaters on SF6 interrupters when ambient temperatures drop below -30 degrees Celsius. While there is normally margin within the design and tolerances of individual pieces of equipment, operating the equipment outside its specified ambient range can result in issues. The challenge of freeze protection of instrumentation and sensors in regions that have not been exposed to long durations of freezing temperatures continues to create operational risk with utilities who are confronted with trying to determine how far to extend freeze protection measures and how it can be justified. From the experiences in Texas in 2021, the implications to the reliability and resiliency of the power grid are tremendous.

Black & Veatch’s environmental and engineering teams are experienced in assessing the risk of abnormal ambient conditions and work with clients to develop optimal solutions and harden critical equipment to operate through those conditions.

3. Wetlands are repositioning.

Wetland boundaries can change substantially, threatening projects with a big change order if they are found to be in a wetland in detailed design.

Black & Veatch has worked on projects where the client’s substation site or t-line route touched a wetland that wasn’t known or mapped during siting/routing. This required permitting and design upgrades, delaying schedules and adding costs. The National Wetland Inventory map, which is developed from simplified algorithms, is often outdated and can vary substantially from current site wetland conditions, all of which can trigger substantial permitting and construction costs and schedule delays.

We recommend performing siting/routing due diligence studies to review environmental permitting implications before advancing to the execution plan and EPC bidding. Completing a wetland delineation survey before accepting bids on major capital projects can save headaches down the line. Building in challenging permitting areas can require helical piles, rock anchors and helicopter installs. Leveraging a consultant to evaluate options and provide expertise in these areas can save utilities time and resources.

Wetlands are repositioning

4. Older steel structures weren’t designed for increasingly high winds.

Aging substations are often not designed to withstand higher wind loads. These structures can fail during a storm and damage the equipment they support, causing long unplanned outages and costly equipment replacements.

Black & Veatch witnessed a project where existing structures, commonly used throughout the client’s sites, were not designed to wind speeds of current code or client’s design wind load (higher than code because hurricane level winds are becoming more frequent). The client wanted to replace and add new equipment to the steel structure. Observation unveiled that several steel members were already deformed, and analysis proved that the structure was overloaded by the wind and equipment. Black & Veatch was retained to analyze the structure and recommend steel and foundation changes to support upgraded equipment and new steel to meet hurricane load winds. We were able to point to select members needing reinforcement to bring old structures up to code, recommend a path to replacing old structures and provide structures for adjacent new bays to meet higher client design wind load for hurricane level winds.

Watch out for deformed or rusted members. Don’t add equipment to existing structures without confirming a structure’s capacity or comparing the new and old equipment to verify that the new equipment will not worsen the structure’s condition. If structures can’t support new equipment, find a plan to reinforce/replace and build stand-alone structures in the meantime. It’s worth the few weeks’ time to analyze the structure so you know its capacity. Existing structures may be nearing their end of life, and replacement may be advantageous in many cases.

5. Extreme weather events are potentially damaging to aging transmission lines.

Older transmission lines are vulnerable; many have degraded hardware, increasing the risk that the lines will fail during storms. Adding to risk for operating utilities is the frequency and co-incidence of storms with other widespread events such as an extreme drought or polar vortex. A lack of routine inspections can contribute a greater risk of failure and unplanned outages, especially when these lines are pushed beyond their original design limits. In addition, landowners along the right-of-way may have made changes which create clearance to line issues so downed lines could pose an even greater safety risk.

Black & Veatch has been asked to assist on several projects where older transmission lines had right-of-way encroachments or damaged hardware. Many times, the legacy rights-of-way are much narrower than typical, limiting possible upgrades. Landowner coordination challenges further exacerbates these issues.

We have executed several inspection programs (including some that used drones with high-resolution photography for line inspection) and developed proactive and prioritized maintenance plans for clients to handle aging lines. This included identifying when upgrades could best mitigate risks, for example, through conversion to underground lines.

6. Increased wildfires make less frequent distribution line inspections risky.

The length of distribution lines and quantity of assets can make managing the regular physical inspections, repairs and coordination with capital improvements difficult. This can lead to suboptimal timing of capital and expense spending, leaving unplanned outage risks unaddressed. This has only heightened as climate change has driven increasingly extreme wildfire danger.

Many clients are unable to manage the workload to inspect their distribution assets. Using drone or in-person inspections and desktop data review, Black & Veatch has determined risk levels of aged assets to help clients prioritize and reduce risk. This includes identifying upgrades to animal protection equipment, physical repairs or outright reconstruction, undergrounding lines and performing additional vegetation maintenance. We can also identify portions of the system to target utility-owned distributed energy resource deployments based on reliability or other outage concerns.

 

Increased wildfires make less frequent distribution line inspections risky

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