As California cools down after the summer, the rainy season is here. While most of California is expected to be warmer-and-drier than usual in a La Niña winter, rain (and snow) is expected. Is your facility prepared for the rainy season?
Requirements
Any facility that discharges stormwater associated with industrial activity to waters of the United States is covered by the
Industrial General Permit (IGP). IGP requires the facilities to conduct stormwater sampling, monitoring, and reporting, among other requirements.
Sampling
Notice of Intent (NOI) facilities must collect and analyze stormwater samples from two (2) qualifying storm events (QSE) for each half of the reporting year (July 2024-June 2025). A QSE is a precipitation event that produces a discharge for at least one drainage area and is preceded by at least 48 hours with no discharge from any drainage area. Samples from each discharge location shall be collected within four (4) hours of the start of the discharge; however, if a QSE starts while a facility is not operating), samples must be collected within 12 hours of the start of the QSE. Stormwater samples need to be sent to the testing laboratory within 48 hours of sampling.
All NOI facilities are required to analyze stormwater samples for total suspended solids (TSS), oil and grease (O&G), and pH. TSS measures the number of solid particles in stormwater. O&G measures the amount of oil residuals and contaminants in stormwater. pH is a measure of how acidic or basic stormwater is. Additional parameters may be required to be analyzed depending on your industry. All parameters except for pH are analyzed by a laboratory. pH must be measured in the field within 15 minutes of taking the stormwater sample using either litmus paper or a calibrated pH meter.
Monitoring
The IGP requires facilities to conduct Sampling Event Visual Observations at the same time that sampling occurs at each discharge location. Facilities are required to observe whether stormwater is discharged from containment sources, the presence or absence of floating and suspended materials, oil and grease, discolorations, turbidity, odors, trash/debris, and source(s) of any discharged pollutants.
Reporting
Facilities must submit sampling and analytical results for all samples via Stormwater Multiple Application and Report Tracking System (SMARTS) within 30 days of obtaining or receiving the results from the lab.
Tips for a Successful Rainy Season
- Prepare for rain early! We recommend ordering sampling kits in advance of rain and maintaining a backup kit onsite in case of any issues. Make sure to check the sampling kits to confirm that you have the necessary bottles for the pollutants your facility needs to sample for and that bottles are not expired. Ensure that you have the adequate supplies for testing for pH onsite including litmus paper, pH probe, and calibration buffers for your pH probe.
- Check the forecast. Check the forecast weekly to make sure you know when rain is coming. If you’re expecting rain, check the forecast more frequently to ensure that you’re aware of potential QSEs.
- Focus on best management practices (BMPs) prior to rain events. We recommend prioritizing your BMPs, including good housekeeping, prior to sampling. Make sure that your structural BMPs are in good condition including downspout filters, wattles, catch basins, or treatment systems.
- Conduct training. Ensure your SWPPP team members are trained and confident in stormwater sampling, especially if you have had turnover since the last rainy season. At least one person per shift should be trained to sample stormwater.
- Keep track of your sampling results. After each QSE, compare your sampling results to your facility’s applicable limits in the IGP. Don’t forget to check for NALs, NELs, and TNALs.
If your facility needs any assistance with stormwater sampling, reporting, or benchmarking, please don’t hesitate to contact Trinity’s local offices in California.
