How often must stormwater SWPPP controls be inspected during an Arizona build?

During an active build, you must inspect your stormwater controls on one of two routine schedules. You pick which one at the start. The schedules come from the Arizona Department of Environmental Quality (ADEQ) Construction General Permit (CGP). Either the site "will be inspected a minimum of once within seven (7) calendar days." Or it "will be inspected a minimum of once within 14-calendar days" plus "within 24-hours of a storm event producing 0.5 inches or more of rain in 24 hours." That is the core rule. The seven-day option is simpler to track. The 14-day option means fewer routine inspections, but you must also inspect after every half-inch storm. These inspections check that the controls in your Stormwater Pollution Prevention Plan (SWPPP) still work and that the plan is being followed. The schedule you choose has to be written into the SWPPP.

This page covers the two routine schedules, the storm-event rule, when you can inspect less often, and how the inspection duty fits the rest of your stormwater permit. It is the operating companion to the front-end SWPPP gate and the back-end permit close-out.

The two routine inspection schedules

You choose between a seven-day schedule and a 14-day-plus-storm schedule. You must write the choice into your SWPPP. ADEQ's CGP, currently AZG2025-001, sets the two out side by side in Part 4. The permit says "at a minimum, the operator shall conduct a site inspection in accordance with one of the schedules listed below." That schedule "shall be documented in the SWPPP and updated as necessary."

Here is what each one requires:

• Seven-day schedule. The site is "inspected a minimum of once within seven (7) calendar days, but not within five (5) calendar days of the previous inspection." So you inspect about weekly, and you cannot bunch two inspections too close together to game the rule.
• 14-day-plus-storm schedule. The site is "inspected a minimum of once within 14-calendar days, but not within 10-calendar days of the previous inspection," and also "within 24-hours of a storm event producing 0.5 inches or more of rain in 24 hours."

The trade-off is real. The seven-day schedule gives you a steady rhythm with no rain math. The 14-day schedule cuts routine inspections roughly in half. But it ties extra inspections to the weather. On a Phoenix-area build, that matters most during monsoon season. A single afternoon storm can start a 24-hour inspection clock. Many builders on active desert sites pick the seven-day schedule to avoid chasing rain gauges in July and August.

Inspections also have to be done by qualified personnel, as the permit defines that term. That is not just anyone on the crew. Under Part 4.2.8, inspections "are only required during the site's normal working hours." If a non-rainfall inspection day lands on a Saturday or holiday, you may inspect the preceding workday. A Sunday shifts to the following Monday.

The storm-event rule and the rain gauge

If you choose the 14-day schedule, a half-inch storm triggers an inspection you must finish within 24 hours, and you have to track rainfall to know when that happens. This is the part owners miss. The permit requires that for the 14-day option, when "a storm event produces 0.5 inches or more of rain within a 24-hour period," including several smaller storms that together top 0.5 inches in a day, "the operator shall conduct an inspection within 24-hours after each occurrence of 0.5 inches of rain within 24-hours, throughout the remainder of the storm."

To know whether you hit that threshold, the permit makes you measure rain. Under Part 4.2.2, you "shall keep a properly maintained rain gauge on the site" or pull rain data from a nearby weather station. The source you use has to be named in the SWPPP. There is also a lower logging trigger. Any day with "0.25 inch or greater" of rain during business hours has to be written into the SWPPP. So a quarter-inch gets logged. A half-inch on the 14-day schedule sends an inspector out.

One timing relief applies. If a rain event hits on a weekend or holiday, the storm inspection "may be conducted the following workday." That keeps a crew from having to mobilize on a Sunday for a Saturday storm, while still requiring the inspection.

When you can inspect less often

You can drop to a reduced schedule once the whole site is stabilized, inactive, or shut down for the season, and the permit spells out each case. These exceptions exist because a stabilized or idle site sheds far less sediment than open, freshly graded dirt. The permit lays out several reduced tracks:

• Reduced (stabilized) schedule. If "the entire site has been temporarily stabilized," or discharges are unlikely based on seasonal rainfall, the site is "inspected at least once per month (but not within 14-calendar days of the previous inspection); and before an anticipated storm event; and within 24-hours of each storm event producing 0.25 inches or more of rain in 24 hours."
• Inactive and unstaffed sites. Before going idle, you do a full inspection and get all controls operational. Then, while inactive, you "perform an inspection at least once every six (6) months and within 24-hours of each storm event producing 0.25 inches or more of rain," with non-storm inspections kept "at least three (3) months apart." You also have to keep a signed statement in the SWPPP that the site is inactive and unstaffed.
• Arid or drought periods. During a seasonally dry or drought period, you "may reduce the frequency of inspections to once (1x) per month" plus within 24 hours of a 0.25-inch storm. You note the start and end dates of the dry period in the SWPPP.

The catch on all of these: the moment the site becomes active or staffed again, the exception ends and you "immediately resume the routine inspection schedule." So a reduced schedule is for a genuinely quiet site, not a way to skip inspections during a slow stretch of active work.

How inspections fit the rest of the stormwater permit

Self-inspection is the ongoing duty that runs between the start and end of your stormwater permit. It links the front-end gate to the back-end close-out. You open coverage by writing a SWPPP and filing a Notice of Intent. You run these inspections the whole time the ground is open. You close out by filing a Notice of Termination once the site reaches final stabilization. The inspections, recorded in the SWPPP, are the proof your controls did their job in between.

For the permit that requires the SWPPP in the first place, and how it differs from the dust permit, see the difference between a dust control permit and a stormwater SWPPP permit and whether you need a grading or earthwork permit and a SWPPP before you break ground. For how the permit ends, see what the AZPDES Notice of Termination and final stabilization are at the end of a build. Skipping inspections is not a paperwork slip. It is a permit violation that can carry penalties and complicate your close-out.

ADEQ's permit version, schedules, and thresholds can change when the CGP is reissued. So confirm the current inspection frequency and storm thresholds against the active AZG2025-001 CGP and ADEQ before you rely on a specific number. On a managed build, your general contractor sets the inspection schedule in the SWPPP and keeps the inspection records current. At Jematell Homes, the stormwater inspections run on schedule from the first cut of dirt through final stabilization, so the permit stays in good standing and closes cleanly at the end.

The Jematell Homes approach

We handle jurisdiction, submittals, and inspections as part of every build. Every project is different, so we will confirm the specifics for your parcel and budget with you directly.

Sources

• ADEQ: AZG2025-001 Construction General Permit (Part 4 Inspections; routine 7-day and 14-day schedules; storm-event and reduced inspections)
• ADEQ: AZPDES Construction Activity General Permit (CGP) for Stormwater
• ADEQ: Construction General Permit (CGP) FAQs