Rain-Event Inspections

When does rain trigger a SWPPP inspection?

The sky holds one of the standard schedule's two triggers. TXR150000's standard schedule requires construction site inspections at least once every 14 calendar days and within 24 hours of the end of a storm event of 0.5 inches or greater.

The rain half of that sentence has more moving parts than it looks — and they are where sites get caught. The rules below are quoted from the permit because the details are the compliance: the threshold, the windows, and the clocks are exactly where good-faith sites slip.

The trigger, precisely

The threshold is cumulative, not per-storm. If a storm event produces 0.5 inches or more of rain within a 24-hour period — including multiple smaller storms that alone produce less but together reach 0.5 inches in 24 hours — an inspection is required within 24 hours of when 0.5 inches of rain or more has fallen. Three small showers that would each be ignorable on their own can add up to a triggered inspection — which is why eyeballing the weather is not a compliance method.

After hours, weekends, and storms that will not quit

The permit anticipates the storm that ends at midnight. When the 24-hour inspection time frame occurs entirely outside of normal working hours, the inspection must be conducted no later than the end of the next business day. It also anticipates the front that parks over a site for days. For a storm that produces 0.5 inches or more on its first day and keeps producing 0.5 inches or more on subsequent days, an inspection is required within 24 hours of the first day and within 24 hours after the last day that produces 0.5 inches or more — two inspections for such a storm event. Two inspections for one long storm — not one, and not five. Knowing which is the difference between compliance and either a gap or a lot of wasted walks.

When the site is unreachable

In the event of flooding or other adverse conditions that prohibit access to the inspection sites, inspections must be conducted as soon as access is practicable. A flooded-out site is not an excused site — it is a deferred one, and the record has to show the walk happened as soon as it could.

Proving the rain

Every one of these rules turns on a measurement. The question that decides a rain-event dispute is simple: how much fell at this site, and when. Answering it takes site-specific rain data, not the airport's. On the platform, weather events are tracked for each site, with precipitation totals in the weather data. When the question comes — did that storm trigger an inspection at this site — the answer comes from the site's own data, not from a gauge across the county. That is also why the engagement treats rain data as part of the record rather than a lookup done after the fact: the measurement that triggers a walk is the same measurement an auditor will ask about a year later, and it has to be site-specific, contemporaneous, and kept.

One engagement, both halves

Storm response is not a separate product bolted onto the schedule; it is the same inspectors, the same standard, and the same record, activated by weather instead of the calendar. Sites that treat rain-event coverage as an afterthought discover the gaps at the worst time — in an enforcement file, storm by storm, with the rain totals sitting next to the missing reports.

The clock on the write-up

The walk is half the duty; the paper is the other half. TXR150000 requires a report summarizing the scope of any inspection to be completed within 24 hours following the inspection. Terradyne's standard inspection engagement runs on the 14-day-plus-rain schedule. The storm response and the routine rhythm ride one engagement, one record, one standard.