Introduction

Floods are a common natural disaster in the U.S. When they happen, an underground storage tank (UST) is vulnerable to damage that could cause an environmental release of its contents. UST owners and operators have a responsibility to act as first responders in most UST emergencies and are typically accountable for initial response and cleanup of UST system releases. Quick UST actions can protect human health and the environment when a flood arrives. This Fact File gives a detailed look at UST precautions to take before a flood occurs and actions to take after. It also explains what effects flooding has on UST systems.

Background

Potential sources of floods can arise from many different types of areas and situations. Some examples include swollen rivers or streams, flash floods, levee or dam failure, spring thaw, or coastal or urban locales. Online flood maps such as the FEMA Flood Map Service Center (MSC) provide a better understanding of the threat of flooding near you.

Floods that damage UST parts can be expensive to repair and clean up after. Being prepared can save you time and money in the long-run.

The subsequent impacts on UST systems could arise because of flooding:

• Buoyancy — Flood waters or saturated soil may offset the restraint of backfill, pavement, or hold-down straps causing the tank to shift. If the UST is unanchored, it could lift out of the ground and float. This could end in a rupture or separation of the connecting pipes – discharging product into the environment.
• Erosion and Scour — Quickly moving water can cause soil erosion and scour. This could expose the system to stressors from the water pressure or floating debris. Furthermore, underground piping can shift and become detached, releasing product.
• Product Displacement — During a flood, water or debris can enter the UST through openings such as fill and vent pipes, loose fittings, or damaged tank walls. As water and debris settle downward, product will float to the top until it’s released into the environment.
• Electrical System Damage — Prolonged contact with flood waters may damage electrical equipment like automatic tank gauging systems, panel boxes, shutoff switches, submersible turbine pumps, dispensers, motors, and/or cathodic protection.

Areas can be so affected by flooding that it can be challenging to even find the UST due to all the mud and debris.

Actions before a flood

Owners and operators should take the following precautions if a flood may occur:

• Conduct an inspection of the facility to identify locations prone to flooding and the possible consequences if a flood occurs.
• Turn off power to the UST system including dispensers, pumps, turbines, automatic tank gauging (ATG) consoles, lighting, and any other system components.
• Take product inventory and water level readings of all tanks.
• Lower the potential of a tank rise.
  • Put heavy objects such as a dumpster, sandbags, or hefty containers filled with sand or rock, over the tank.
  • Fill the tank with fuel to reduce buoyancy by weighing down the tank so it will not float out of the ground.
• Ensure fill caps are operable and secure.
• Place sandbags on top of the spill catch basin and tank top sump lids to lessen the amount of water entering each tank.
• Ensure the seal on spill bucket plungers are working to keep water out of the tank. If possible, have a UST technician drain product lines back into each tank.
• Close flow restrictors and manually trip shear valves on pressurized piping to prevent product releases from dispenser lines.
• Momentarily cap off vent pipes to prevent water from coming into the tank and relocating product.
• Protect fuel pump and controls to prevent flood damage.
  • Secure dispensers with plastic, tarps, or plywood.
• If relevant, check the remediation system.

Actions after a flood

Owners and operators should take the following actions after flood waters recede and re-entry is allowed:

• Ensure power is off to any UST-related equipment.
• Determine if water or debris entered the UST and remove all debris and water from the concrete pad.
• Inspect the concrete pad for tank movement or shifting and UST system components for leaks.
• Measure product and water levels in each tank.
• Ensure remaining product is suitable for use.
• After inspecting the electrical system, return power to the UST system. Have a technician inspect for correct operation.
• Inspect vent lines for movement and cracking.
• If applicable, test the cathodic protection system for correct operation.
• Clean and empty all spill buckets, under-dispenser containment, and containment sumps.
• Clean and lubricate shear valves before resetting them.
• Watch for unfamiliar operating conditions like sluggish fuel dispensing, recurrent alarms, customer complaints, or equipment shutdowns.

Applicable laws & regulations

40 CFR 280 — Technical Standards and Corrective Action Requirements for Owners and Operators of Underground Storage Tanks (UST)

Related definitions

Cathodic protection: An electrical system for prevention of rust, corrosion, and pitting of metal surfaces which are in contact with water or soil.

Underground storage tank: Any one or combination of tanks that is used to contain an accumulation of regulated substances, and the volume of which is 10 percent or more beneath the surface of the ground.

Key to remember

Owners and operators should contact their financial institution or insurance provider to file a notice or claim and identify minimum requirements for continuing coverage. Failure to do so could risk coverage in the event of a successive release. In some cases, funds may be provided for immediate actions or longer-term cleanup and site recovery. State financial assurance programs may give loans and grants to qualified owners and operators. State trust funds could reimburse parties for corrective actions if prerequisites for coverage are met. In cases of emergency, states may use Leaking Underground Storage Tank (LUST) Trust Fund money to conduct emergency responses, site assessments, or remedial actions. Check with your state environmental agency to determine what funding is available.

Real world example

Flood events can be relatively isolated or far-reaching. In 2017, flooding from Hurricane Harvey caused over two dozen storage tanks, containing a total of more than 145,000 gallons of crude oil, gasoline, and various other contaminants to rupture or fail when the hurricane crashed into the coastline of Texas. This catastrophic event followed years of warnings that the area was not prepared for a major storm. Roughly one-third of the 4,500 storage tanks along the Houston Ship Channel were in locations vulnerable to flooding.

While some did suffer damage, other refineries were able to fill up their tanks to make them less buoyant before the storm arrived. Therefore, they were less prone to floating and subsequent damaged. Regulations require companies to prepare for spills. But regardless of this, companies still struggle to prepare for extreme weather events that can cause UST systems to fail. Make sure to properly prepare not just for floods, but other natural disasters to avoid UST damage, leaks, and harm to those nearby.