If you are comparing stormwater sampling services for your facility, you have probably noticed that most providers offer to send a field technician out to collect your samples. CDMS does not. We ship you a sampling kit and your own team collects the sample when it rains. That difference looks small on a proposal. Over a season, it changes what you pay and how reliably you stay in compliance.
This piece explains why we built the service this way, what the two models actually cost you, and the one situation where the kit model is not the right fit. For how sampling works under the permit in the first place, see our SWPPP sampling in California guide. For the broader service, start with our SWPPP and stormwater compliance overview.
The Problem With the Field-Technician Model
Stormwater sampling in California runs on the weather, not on a calendar. Under the Industrial General Permit (IGP), you have to collect your sample from a qualifying storm event (QSE): a rain that produces a discharge after about two dry days. You also have to catch it within four hours of when discharge begins, during your operating hours.
Now picture a consultant who sends a technician to do that. They schedule a visit. The technician drives out. But the storm is light, or it already passed overnight, or it does not produce a discharge. There is no qualifying sample to collect. The trip still gets billed.
We hear this from facilities that call us after leaving another provider. We hear it all the time: the technician shows up on site, there is not enough rain to collect a sample, and the client gets charged for an extra site visit anyway. Those charges add up across a rainy season, and they rarely appear in the original proposal. You priced the service against a clean quote and ended up paying for trips that produced nothing.
How the Kit-Based Model Works
CDMS ships you a turnkey sampling kit: the bottles, the chain-of-custody forms, pH test strips, a cooler, and step-by-step instructions. We send the kits one at a time across the sampling season so the timing lines up with when you need them. When a qualifying storm hits, the people already standing in your building collect the sample. No one has to drive anywhere or predict the weather a week out.
From there, we handle the parts that need a specialist. We coordinate the lab, interpret the results against the Numeric Action Levels in your permit, and prepare everything for upload to SMARTS, the State Water Board’s online stormwater reporting portal. You collect the water. We handle the compliance.
The reason this works comes back to the four-hour window. Your staff is already on site when the rain starts. They can walk to the discharge point and fill a bottle inside the window without anyone scrambling. A scheduled technician cannot reliably beat your own people to a storm that nobody can schedule.
Field-Technician vs. Kit-Based: Side by Side
| Field-Technician Model | Kit-Based Model (CDMS) | |
|---|---|---|
| Cost | Per-visit charges, including trips that produce no sample | One kit-based service; no per-trip site-visit fees |
| Timing | Tied to a scheduled visit that may miss the qualifying storm | Sample collected the moment a qualifying storm hits, by staff already on site |
| Dry-visit risk | High: a visit with no qualifying rain still gets billed | None: no trip means no trip charge |
| Client effort | Low at the moment of collection; higher cost and less control | Your team fills the bottle; CDMS handles lab, results, and SMARTS |
| Collection timing | Depends on the technician arriving inside the four-hour window | On-site staff collect inside the window, with kit instructions and our review |
Want to know what your facility’s sampling looks like on the kit model? Call (925) 551-7300 or request a consultation. Tell us your discharge points and who is on site during the rainy season, and we will lay out the kit schedule for your reporting year.
When the Kit Model Isn’t the Right Fit
We would rather tell you this up front than sell around it. The kit model depends on someone being on site, and able to step outside, during a qualifying storm. For most manufacturers, distributors, food processors, and warehouses, that is a normal workday. Someone is always there.
If your site runs unstaffed for long stretches, or no one on the team can safely reach the discharge points during a storm, the kit model gets harder. In those cases we talk through the options before you commit, including how to assign and train a sampler so the responsibility does not fall on a single person. The goal is a sampling program that actually catches your events, not one that looks tidy on paper and then misses storms.
The Bottom Line
Both models put a bottle of stormwater in front of a lab. The difference is what it costs you to get there and how often you actually catch the storm. The field-technician model adds trips, and trips that come up dry still get billed. The kit model puts collection in the hands of people who are already on site and keeps the specialist work, the lab coordination, the results, and the SMARTS reporting, with us.
If cost is what is driving your comparison, the dry-visit charge is the line item to watch for. Our SWPPP cost guide walks through every factor that moves the price, including this one.
Comparing stormwater sampling services and want a clear quote with no dry-visit surprises? Call (925) 551-7300 or request a consultation. Tell us what runs on your site and who is there when it rains, and we will scope a kit-based program with a fixed-price quote up front.
