Preparing For Monthly or Quarterly Municipal/City Inspections

A lot of projects occur within MS4 permitted areas. An MS4 is a municipal separate storm sewer system (MS4). The water board will issue MS4 Phase 1 or MS4 Phase 2 (AKA “small MS4 permit”) to a municipality depending on the population size.

Phase 1 MS4 serves a population greater than or equal to 100,000 people while Phase 2 MS4 serves a population greater than or equal to 10,000 people. An MS4 permit can be issued to a county, city, university, department of transportation (airports, harbors and highways), military bases, and so on.

MS4 permit holders are required to conduct inspections of construction sites that occur within their jurisdiction at a frequency of monthly or quarterly depending on the particular permit.

Additionally, MS4 permit holders are required to develop a Storm Water Management Plan that include minimal control measures, such as construction site runoff control and associated inspection and enforcement procedures. These inspections can be scheduled in advance, done via random site visits, or even performed as “wet weather” inspections.

Certain municipalities do have the ability to levy fines for stormwater deficiencies and re-inspections of construction sites. Although it can be difficult for them to establish large fines, municipalities do have more enforcement authority if a non-storm water discharge was observed into their MS4. Therefore, the municipal inspector may conduct a “wet weather” inspection during rain to observe any non-storm water discharges into their MS4.

A former municipal MS4 inspector and TCG employee, Sean Cusick, put together some general tips that can “set the tone” for a positive municipal inspection.


Municipal inspections start with documentation reviews – set the tone early by being organized and prepared! Be prepared for random site inspections. Always have your paper work and documentation onsite and up to date.

A. Ensure your Water Pollution Control Drawings (WPCDs), Erosion Controls Plans and Site Specific BMP plans are up to date with BMPs and Waste Management Areas identified, and are in the correct locations to match existing site conditions. If your WPCDs specify silt fence perimeter controls and you installed fiber roll perimeter controls, this must be reflected in updated WPCDs. The same goes if you have identified your concrete washout to be located in your staging area, but there are several temporary washout bins (even kitty pool bins!) located through-out your project site. It can even be penciled and initialed on the WPCDs.

B. Have all your Weekly, Pre-Storm, During Storm, and Post-Storm inspections printed in a binder or on a desktop/laptop within the onsite trailer.

If all your BMP inspection and WPCD maps are up to date and located in one easily accessible onsite location (binder/folder/desktop hard-drive), this indicates to the Municipal Inspector that you are serious about storm water pollution prevention and NPDES general construction permit compliance.


During documentation review, the city inspector will ask to see any weekly, pre, during or post storm BMP inspection reports. First, the inspector will check to see the reports are being completed for the last month, and then they will check to see if there are any identified corrective actions and if the corrective actions have been rectified/addressed .

A. Make sure that corrections begin with 72 hrs of identification. The inspector does not want to see repetitive corrective actions on BMP reports from week to week. If the inspectors see the same deficiency on consecutive reports, they may think that you have not taken storm water pollution prevention and NPDES general construction permit compliance seriously, and will most likely spend more time at your site inspecting BMPs.

B. Corrective actions within BMP reports are good! The inspector wants to see that the contractor’s SWPPP inspector or QSP is identifying deficiencies or corrective actions. No construction site is perfect and the Municipal inspector knows this – If there are no corrective actions on your BMP inspection reports the Municipal inspector will question if the QSP performed a thorough inspection. As a result the Inspector will most likely perform a more detailed inspection and spend more time at your site inspecting BMPs.


Store materials properly, dispose of scrap materials/wastes in a timely manner, clean-up any spills promptly, clean-up trash and litter from site, and sweep sediment from paved areas.

During the onsite inspection if the municipal inspector observed concrete waste leaking from concrete bins or spilled material that hasn’t been cleaned-up, this will be an indication to the inspector that more SWPPP training is needed. These general housekeeping BMPs tend to indicate the overall culture of the contractor (tidy vs. messy).

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