March 12, 2021

Water Line Freeze Protection: Preventative Design and Preparation for Cold

Brian Wright, PE

After a record setting cold snap, discussing preventions about freeze damage and downtime is like advising someone to close the barn door after the horse is gone. But wait, the door is frozen open…

What if this is not the last horse and the issue happens repeatedly because we are not prepared?

During my many years doing business in Montana, where temperatures every winter could be expected to reach -40 degrees (F or C!), I became very acquainted with designing, preparing, and repairing for freezing events.

Design: Most of the 500 pump stations that I designed and constructed did not need to operate during freezing temperatures, but many did. One pump station for snowmaking only operated when temps were well below freezing and even below zero. Even the pumps and piping that only operated above freezing still needed to be easily prepped for many fall and spring cold snaps that dropped to single digits. Issues to remember in design include the following:

·       Small diameter piping should be insulated and heat traced or include accessible drains.

·       Heat tracing thermostats need to be located out of sunlight or away from heat sources to properly prevent freezing. Heat tracing “on” indicator lights assist maintenance personnel.

·       Captive water that cannot circulate to warmer buried piping needs special attention, as it freezes rapidly.

·       Buried piping and the use of valve vaults and air vent vaults can utilize ground heat.

·       Consider temperature gradients between cold air and warm earth or heated structures when locating piping during design.

·       Vulnerable items such as cast pump/valves cases and air vents need special consideration.

·       Consider lower temperatures for design than historical minimums.

Prepare: A well designed system will make preparation for cold weather easier, but in any case, one eye must always be looking at the weather forecast with winterization in mind. Whether shutting down or winterizing for continuous operation, knowing the personnel and schedule required is imperative. Items to be properly prepared include:

·       Having checklists for winterization and making sure that heaters and drains are operational.

·       Ensuring safety during winterizing and installing insulation and heating equipment.

·       Keeping a log of previous problem areas or equipment, including winterizing improvements.

·       Deciding when action must be taken depending upon time required and failure consequences.

·       Have spare parts for at-risk items that have been repaired in the past and cannot be winterized.

Repair: After freeze damage occurs, make sure to not only repair the damage quickly and safely, but also make changes or plans for changes to equipment or procedures to avoid re-occurrence. It will get cold again….

No matter where you are, temperature can vary greatly and change suddenly.

For more information on freeze protection and how to prepare for cold weather, please contact Brian Wright, PE, at bwright@plummer.com.

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