Where to Look Up Your Standard Industrial Classification Code, Why Your Primary Activity Decides It, and How That Four-Digit Number Points You Toward the 5G2 or an Industry-Specific New Jersey Stormwater Permit
If you've started looking into whether your facility needs a stormwater permit in New Jersey, you've probably run into a request for something called an SIC code and wondered what it has to do with rainwater. An SIC code, short for Standard Industrial Classification code, is a four-digit number that describes the main thing a business does at a specific location. The New Jersey Department of Environmental Protection (NJDEP) uses that number as the first filter for its industrial stormwater program. You can look yours up for free in the federal SIC manual that OSHA keeps online, or find it on an existing permit or past filing. Once you have it, the code tells you whether NJDEP considers your site industrial at all, and if it does, whether you should be looking at the Basic Industrial Stormwater General Permit (called the 5G2) or one of New Jersey's industry-specific permits for businesses like concrete, asphalt, quarrying, scrap metal, or vehicle recycling.
In this article, we'll walk through what an SIC code is and why New Jersey still relies on it, the best places to find yours, and how to choose the right code when your site does more than one thing. We'll also cover how the code connects to the federal list of regulated industries, give you a mapping table that links common codes to New Jersey's permit categories, and point out the mistakes that send facilities down the wrong path. If you'd rather have someone look at your operation and tell you where you land, feel free to reach out to RMA.
Table of Contents
TL;DR
Your SIC code is a four-digit number describing the main activity at your site, and you can look it up for free in OSHA's online SIC manual or find it on past permits and filings. NJDEP uses it to decide whether your site is industrial for stormwater purposes and which permit fits. Concrete products, hot mix asphalt, mining and quarrying, sand and gravel, scrap metal, vehicle recycling, and wood waste or leaf composting operations each have their own New Jersey general permit. Other regulated facilities look at the basic 5G2 permit, which only works if nothing industrial is left out in the rain, or else an individual permit or a no exposure exclusion.
What Is an SIC Code and Why Does NJDEP Use It for Stormwater Permits?
The Standard Industrial Classification system was created by the federal government to sort businesses by what they do. Each four-digit code gets more specific as you read it left to right. The first two digits are the major industry group, the third narrows it to an industry group, and the fourth names the specific industry. So 32 is stone, clay, glass, and concrete products, 327 is concrete, gypsum, and plaster products, and 3273 is ready-mixed concrete. The manual everyone still uses is the 1987 edition, and it hasn't been updated since.
You might reasonably ask why a 1987 manual still matters when most of the government moved to the newer six-digit North American Industry Classification System (NAICS). The answer is that the federal stormwater rules were written around SIC codes in 1990, and New Jersey built its industrial stormwater program on top of them. The federal definition of "stormwater associated with industrial activity" at 40 CFR 122.26(b)(14) lists regulated industries mostly by SIC code, and NJDEP's rules under N.J.A.C. 7:14A follow the same approach. That's why NJDEP's permit documents name SIC codes first and list the matching NAICS codes alongside them. If you want the background on that federal definition, our article on stormwater associated with industrial activity walks through it.
For a New Jersey facility, the code does two jobs. First, it answers the threshold question of whether NJDEP considers your site industrial for stormwater purposes at all. Second, if it does, the code steers you toward a specific permit. New Jersey doesn't have one catch-all industrial stormwater permit the way many states do, so landing on the right code is the first step toward landing on the right permit.
Where Can You Find Your Facility's SIC Code?
Nobody mails you an SIC code. It isn't issued by an agency the way a tax ID is, and businesses generally identify their own. That's freeing, but it also means the code you pick has to hold up if NJDEP looks at your operation and disagrees. Here are the places we'd check, roughly in order of usefulness.
| Where to Look |
What You'll Find |
How Much to Trust It |
| OSHA's online SIC manual search |
The full 1987 manual, searchable by keyword, with descriptions of what each code includes |
The best starting point, because it's the actual manual the rules reference |
| Your existing NJDEP permits or past applications |
The code a previous owner or consultant used for this site |
Good, as long as the operation hasn't changed since |
| Other environmental filings (air permits, Community Right to Know, TRI) |
An SIC or NAICS code already reported for the same site |
Useful, and your codes should be consistent across programs |
| Your NAICS code from tax or business records |
A six-digit code you can convert to SIC with the Census Bureau's concordance tables |
Helpful, but conversions aren't always one to one |
| Credit reports, business databases, or SEC filings |
A code assigned to your company as a whole |
Weak, since it often describes the company, not this site |
We'd start with the OSHA search and type in plain words that describe what happens at your site, like "ready mix," "asphalt," "scrap," or "machine shop." Then read the full description for each candidate code, because the descriptions spell out what's included and what's excluded. A code that sounds right from its title sometimes covers something narrower than you'd expect, and the description is where you find that out. Treat codes from credit reports and business databases with caution, since they're usually assigned to the corporation by a data company and can be years out of date. For stormwater, what counts is the activity at the site that's applying.
How Do You Pick Your Primary SIC Code When Your Site Does More Than One Thing?
Lots of facilities do several things at once. A concrete producer might also sell bagged material and run a truck maintenance shop. A recycler might handle scrap metal, used auto parts, and some construction debris. The SIC system handles this by asking for a primary code, which describes the main activity at that location, and the stormwater program works the same way. The general rule of thumb under the federal program is that the primary activity is the one bringing in the most revenue at that site. If that's hard to pin down, look at where most of your employees work or which activity produces the most output.
Secondary codes still matter. Federal and New Jersey stormwater rules can reach certain activities on a site even if they aren't the primary business, and a permit application usually lets you list more than one code. If your site has a significant secondary operation that would be regulated on its own, like an asphalt plant sitting on a quarry property, list it and expect that it may affect which permit fits.
Transportation businesses are the classic example of how this plays out. Trucking terminals, bus companies, and similar operations fall under SIC codes the federal rules treat as industrial, but only for their vehicle maintenance, equipment cleaning, fueling-related, and deicing areas. A trucking company that parks trucks and sends them out for service may not need a permit at all, while the same company with an outdoor maintenance bay may.
Whatever you land on, the code should describe this site as it runs today. If you bought a plant that used to do something different, or you've added or dropped an operation, don't copy the old code forward without checking it.
Does Your SIC Code Mean You Need a New Jersey Stormwater Permit?
Your code doesn't decide everything on its own, but it decides which side of the line you start on. The federal definition sorts regulated industry into eleven categories, and most of them are tied to SIC codes. The table below covers the code-based categories in plain terms. The others are described by activity rather than code, such as facilities with federal effluent guidelines, hazardous waste treatment and disposal sites, landfills, steam electric power plants, larger sewage treatment plants, and construction.
| SIC Codes |
Types of Businesses |
How They're Treated |
| 10 through 14 |
Mining and quarrying, including sand and gravel |
Regulated |
| 24, 26, 28, 29, 311, 32, 33, 3441, 373 (with some exceptions) |
Heavier manufacturing such as lumber, paper, chemicals, petroleum refining, stone and concrete products, primary metals |
Regulated |
| 5015 and 5093 |
Used auto parts, salvage yards, and scrap recycling |
Regulated |
| 40 through 45 and 5171 (with some exceptions) |
Railroads, trucking, buses, shipping, airports, petroleum bulk stations |
Regulated only for vehicle maintenance, equipment cleaning, fueling-related, and deicing areas |
| 20 through 23, 25, 27, 30, 31, 34 through 39, 4221 through 4225, and others |
Lighter manufacturing such as food, printing, plastics, fabricated metal, machinery, electronics, plus public warehousing |
Regulated when materials or activities are exposed to rain |
If your code isn't on the list and your activity isn't one of the narrative categories, you most likely don't need an industrial stormwater permit from NJDEP. That's a common outcome for offices, retail stores, many warehouses that aren't public warehousing, data centers, auto body shops, car dealerships, and quick-lube shops. "Most likely" is doing some work in that sentence, though. NJDEP can ask a business it believes is regulated to apply or explain why it doesn't need to, and a site's activities sometimes fit a narrative category even when the code doesn't. Our article on who needs a stormwater permit goes into the broader question.
If your code is on the list, you don't automatically need a full permit either. A facility that keeps all of its industrial materials and activities indoors or under permanent cover may qualify for New Jersey's no exposure exclusion instead, which takes the site out of the permit requirement as long as conditions stay that way. We explain how that works in our article on what non-exposure means under a stormwater permit. Where the water goes matters too. A site that drains to a combined sewer system run by a sewerage authority may be handled under that authority's rules rather than, or alongside, an NJPDES permit, so confirm where your runoff ends up before assuming either way.
Which NJ Stormwater Permit Does Your SIC Code Point To?
Once you know you're in a regulated category, New Jersey's permit lineup comes into play. All of these are part of NJPDES, the New Jersey Pollutant Discharge Elimination System, which is the state's version of the federal NPDES permit program. Most regulated facilities in New Jersey end up under the 5G2, but several industries have their own general permits, and for some of them the SIC code is spelled out right in the eligibility section. The table below is based on NJDEP's current permit pages and permit documents.
| If Your Primary SIC Code Is |
Your Activity |
Look First At |
| 3271, 3272, 3273 |
Concrete block and brick, other concrete products, ready-mixed concrete |
Concrete Products Manufacturing (CPM) general permit |
| 2951 |
Hot mix asphalt manufacturing |
Hot Mix Asphalt Producers (R4) general permit |
| 1411, 1423, 1429, 1442, 1446, 1459 |
Dimension stone, crushed stone, sand and gravel, industrial sand, clay and similar minerals |
Mining and Quarrying (R13) general permit |
| 1442, 1446, or 1499 (soil and fill excavation) |
Sand and gravel operations whose stormwater goes only to groundwater |
Sand and Gravel (RSG) general permit |
| 5093 |
Scrap metal recycling, with or without vehicle recycling |
Scrap Metal (SM2) general permit |
| 5015 |
Dismantling vehicles and selling used parts, without scrap processing |
Vehicle Recycling (RVR) general permit |
| Defined by activity rather than code |
Wood waste recycling and leaf composting |
Wood Waste Recycling and Leaf Composting (WRC) general permit |
| Any other regulated code |
Manufacturing, transportation maintenance, and other listed industries |
5G2 if all exposure is or can be eliminated, otherwise an individual permit, or the no exposure exclusion |
A few details in that table are worth slowing down on. The CPM permit isn't limited to the three codes listed. NJDEP's permit summary says it also reaches facilities doing similar or related work regardless of how they're coded, so a precast or batching operation filed under a different code can still end up there. Our producer's guide to concrete plants and stormwater permits covers what that looks like in practice.
Sand and gravel codes show up twice because the deciding factor is where the water goes. The R13 covers discharges to surface water, while the RSG is for sand and gravel operations whose stormwater goes only to groundwater. Mining and quarrying activities aren't eligible for the 5G2 at all, according to NJDEP.
Scrap and auto recycling split the same way. NJDEP's vehicle recycling permit is for yards that dismantle vehicles and sell used parts. If you also process and recycle scrap materials, NJDEP says you aren't eligible for the RVR, and the scrap metal permit is the one to look at. We break down that permit in our article on the New Jersey SM2 scrap metal permit.
Each of these permits also has its own eligibility exclusions, so use the table to find the right document, then read its eligibility section to confirm you belong there.
When Your SIC Code Points to the 5G2 Basic Industrial Stormwater Permit
If your code is on the regulated list and your industry doesn't have its own New Jersey permit, the 5G2 is usually the first permit to consider. Its name makes it sound like a default permit for any industrial site, and that's where a lot of people get tripped up. NJDEP makes the 5G2 available to regulated facilities that have eliminated, or can eliminate within six months of authorization, all exposure of industrial materials and activities to rain and snowmelt. That means stockpiles, equipment, processing, loading, and storage all have to be inside or under cover.
For facilities that fit, the 5G2 is manageable. It requires a written stormwater plan, which RMA calls a SWPPP (stormwater pollution prevention plan). You'll also see it called an SPPP, an SP3, or just a stormwater plan in New Jersey. The permit also comes with an annual inspection, employee training, and an annual certification, and it doesn't require stormwater sampling. Our article on the 5G2 basic industrial stormwater permit covers those requirements in more depth, and our guide to what a SWPPP is explains the plan itself.
For facilities that don't fit, the answer gets harder. A manufacturer with a regulated code and real outdoor activity, like uncovered storage of metal stock or a yard full of drums, can't use the 5G2 and doesn't have an industry-specific permit to fall back on. Those sites typically need an individual NJPDES permit, which NJDEP writes for that one facility. We explain when that happens in our article on whether you need an individual NJPDES industrial permit. The other path is changing the site, moving or covering what's exposed, so the 5G2 or the no exposure exclusion becomes available.
Common SIC Code Mistakes That Lead to the Wrong NJ Stormwater Permit
Most SIC code problems we run into come from the same few mistakes. Facilities use the company's code instead of the site's, or copy a code from an old permit or a previous owner after the operation has changed. Others pick a code that sounds close enough. A yard that sells used auto parts and one that shreds scrap metal both deal in old cars, but one points toward the RVR and the other toward the scrap metal permit or an individual permit. NAICS conversions cause trouble too, because some NAICS codes split into several SIC codes and the first match isn't always the right one.
The biggest mistake is treating the code as the whole answer. The code tells you where to start, but exposure, drainage, and each permit's eligibility language finish the job. A facility on the wrong permit can miss sampling or plan requirements its correct permit would have imposed, and our article on NJPDES stormwater permit requirements shows how much those requirements can vary.
How RMA Helps With SIC Codes and New Jersey Stormwater Permits
We're a New Jersey based firm, and sorting out which NJPDES permit fits a facility is a big part of what we do every week. If you're not sure whether your SIC code puts you in the regulated universe, whether you belong on the 5G2 or an industry-specific permit, or whether a no exposure exclusion might take you out of the program entirely, we're happy to look at your operation and give you a straight answer. Sometimes that answer is that you don't need a permit at all, and we'll tell you so.
When you do need coverage, we help with the Request for Authorization, the SWPPP, inspections, training, and annual certification, along with sampling where your permit calls for it. There's no obligation to talk it through. You can call us, send an email, or fill out the form on our website, and if you'd like to start the conversation now, just contact RMA here.
