Trigger Levels in residences, commercial areas, and schools: What is the trigger level for a Single Family Dwelling?

• A. 32 sf or 50 lf on pipe
• B. 16 sf or 25 lf on pipe
• C. 64 sf or 100 lf on pipe
• D. 8 sf or 12 lf on pipe

Answer: (A)

In this context, trigger levels are the points at which a release inside a building requires a formal response to protect occupants. They use two measures—square feet of contaminated area and linear feet of piping affected—so you can capture both spills on surfaces and leaks along piping.

For a single-family dwelling, the trigger is 32 square feet or 50 linear feet on pipe. This threshold is chosen because homes have close living spaces and occupants who may have limited ability to evacuate or ventilate quickly, so a relatively modest spill or leak can create meaningful indoor exposure. Using either surface area or pipe length helps ensure that a significant release is recognized promptly, whether the issue is a spill spreading across floor and walls or a leak traveling along piping.

The other values aren’t used for single-family dwellings because they reflect different risk profiles and response needs in larger spaces or different occupancy types. The 32 sf / 50 lf measure provides a conservative, practical trigger appropriate for residences to prompt appropriate action without waiting for a larger, less protective threshold.