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March 14, 2016
Flooding and Floating USTs
By Emily Remmel, JD, Legal Editor

A few weeks ago, the famous groundhog, Punxsutawney Phil, arose from his burrow and did not see his shadow. According to tradition, the absence of Phil’s shadow means spring is on its way. As the ground thaws and the rainy spring season begins, owners of underground storage tanks (USTs) must take certain precautions to prevent tank systems from emerging from belowground and floating away.

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Flooding can happen quickly and is often unpredictable, especially in El Niño cycles. UST system owners must be prepared because these flood events not only have the possibility of releasing regulated substances to the environment but can also rack up huge compliance and enforcement costs.

Before installing a UST system

As a UST owner, you must know if your facility is located in a flood-prone area. To find out if your facility rests in an area with increased flood probability, owners can visit the U.S. Geological Survey’s flood information website.

If your facility is in a flood-prone area, increase the burial depth and the amount of pavement above the UST. This will increase the weight of backfill, and the pavement will help keep the tank from floating. Follow the manufacturer’s recommended burial depth for these areas.

Also, owners should consider anchoring the UST with concrete weights strapped down to both sides of the tank, commonly referred to as deadman anchors. These deadman anchors specifically counter the buoyancy forces caused by saturated soil and keep the tank in place.

What to do before a flood

If the tank system is already in the ground, UST system owners can take a variety of short-term preventive measures to minimize the risk of tank displacement and the release of regulated substances to the environment.

In the threat of a flood, UST system owners should do the following:

  • Turn off all electricity to the UST system.
  • Take product inventory.
  • Fill the tank.
  • Secure all fill caps.
  • Ensure spill bucket plungers and seals are operational.
  • Close the shear valve on piping.
  • Cap off the vent pipe temporarily.
  • Place sandbags on top of the tank.

Use this comprehensive checklist to help prepare your facility for severe weather events.

What to do after a flood

Witnessing the destruction during the moments following a flood event can often be shocking. Debris and damage are likely in areas that were inundated with water. In the wake of a flood event, tank facilities must take a variety of steps to ensure that a regulated product was not released to the environment and to get their UST system back up and running.

After a flood event, UST system owners should do the following:

  • Make sure power is off to any equipment.
  • Determine if the UST released product.
  • Determine if water or debris entered the UST.
  • Return power and check the release detection system.
  • Inspect all equipment for proper operation.
  • Clean and empty spill buckets and sumps.
  • Perform a tightness test.
  • Test the cathodic protection system.

UST facilities can refer to this checklist for steps to take following severe weather events.

Serious weather events, like floods, can greatly increase the chance that a UST system could come out of the ground or release product. With the onslaught of El Niño, UST system owners and operators must be prepared for heavy rains and flooding.

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