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Outdated Rainfall Regulations Leave Texans at Risk of Major Environmental Disasters

The Definitions for Worst-Case Scenario Rain Events Must Change, Report Finds

AUSTIN – Outdated state regulations fail to account for climate change and leave Texans vulnerable to major pollution incidents triggered by severe rainfall events, according to a report from Public Citizen released today as the 2022 Atlantic hurricane season begins.

The report – Under Water and Unaware – comes at the start of a hurricane season that will mark five years since Hurricane Harvey, the most severe rainfall event on record in the country’s history. The storm released millions of pounds of pollution into the air and water when it struck the Texas Gulf Coast and the area’s many industrial facilities in August 2017.

The report makes multiple findings, including that the state’s definitions of a 100- and a 25-year storm are inaccurate and should no longer be applied. Because petrochemical corporations build critical infrastructure to meet the state’s outdated standards for worst-case scenario rainfall events, storage tanks and other equipment at industrial facilities are vulnerable.

“Climate change has made what we thought were once-in-a-lifetime rain events more frequent,” said Adrian Shelley, director of Public Citizen’s Texas Office and author of the report. “Harvey showed what was possible when the petrochemical industry isn’t ready for extreme weather. Texas has ignored climate change for long enough. We either act now or wait for the next major climate disaster. People’s lives are on the line.”

A significant vulnerability is floating roof storage tanks. Petrochemical corporations use these cylindrical tanks to store oil, chemicals, and petroleum products. Because they are not built to account for more frequent and heavier rainfall events that are more common, the tanks’ drainage systems can become saturated, making them more prone to fail and release their contents into the environment. Tanks at nine chemical facilities failed during Harvey alone due to heavy rain.

Severe storms can also lead to power failures and emergency shutdowns at petrochemical facilities, resulting in significant pollution released into the air.

Among the report’s key findings:

  • Texas state rain regulations and the American Petroleum Institute construction standards for floating roof tanks rely on a technical paper – Technical Paper 40 – which was published by the National Weather Service more than 60 years ago and relied on data from a 20-year period beginning in 1938.
  • Texas regulations use outdated data in Technical Paper 40, leading to inadequate definitions for “100-year storm” and “25-year storm.” The National Oceanographic and Atmospheric Administration has new rainfall data available in a document known as Atlas 14 that provides better guidance for how floating roof tanks should be built.
  • During Hurricane Harvey, at least nine petrochemical facilities experienced floating roof tank failures due to heavy rain, releasing three million pounds of air pollution. Updates to regulations related to heavy rain could prevent this pollution.
  • Updating state regulations with data from Atlas 14 would increase the 25-year storm by 2.6 inches, the 100-year storm by 5 inches, and create a new definition for a 1,000-year storm of 29.8 inches.

The report recommends that all state codes referencing rainfall frequency and volume be updated and cite Atlas 14 instead of Technical Paper 4