How to Draw an SPCC Facility Diagram for a New Jersey Site

What a New Jersey SPCC Facility Diagram Has to Show, and How to Build One From Aerial Imagery or Site Plans

The facility diagram is one page, sometimes two, but it carries a lot of weight in an SPCC Plan. It shows a reviewer whether the person who wrote the Plan understood the site, and it's one of the places where we most often find deficiencies: missing containers, wrong capacities, piping that never shows up, or an unlabeled screenshot from a mapping website. For New Jersey facilities, where storm drains and streams are rarely far from the tank yard, a weak diagram also hides the question everyone cares about, which is how oil would reach the water.

This article walks through what the diagram has to show under the federal rule, how to handle containers, transfer areas, piping, secondary containment, drainage, and nearby waters, and how to build the drawing from aerial imagery or site plans. We've included an example diagram for a fictional New Jersey site so you can see how the pieces fit together. If you'd rather hand the whole thing off, you can reach out to RMA and we'll talk it through with you.

Table of Contents

• What Is an SPCC Facility Diagram and What Does the Rule Require?
• What Oil Containers and Equipment Belong on the SPCC Facility Diagram?
• How Do You Show Transfer Areas and Piping on an SPCC Diagram?
• How Should Secondary Containment, Drainage, and Nearby Waters Appear on the Diagram?
• Example SPCC Facility Diagram for a New Jersey Site
• How Do You Build an SPCC Facility Diagram From Aerial Imagery or Site Plans?
• What Are the Most Common SPCC Facility Diagram Mistakes?
• When Does an SPCC Facility Diagram Need to Be Updated or Reviewed by a PE?
• How Does RMA Help With SPCC Facility Diagrams in New Jersey?
• Additional Information About SPCC Facility Diagrams

What Is an SPCC Facility Diagram and What Does the Rule Require?

The SPCC rule requires every Plan to describe the physical layout of the facility and include a facility diagram. The language sits in 40 CFR 112.7(a)(3). The diagram has to mark the location and contents of each fixed oil storage container and the storage area for mobile or portable containers. It has to identify exempt underground tanks and label them "exempt." And it has to show all transfer stations and connecting pipes, including intra-facility gathering lines that are otherwise exempt.

That's the legal minimum. In practice, a reviewer walking your site will hold the drawing in one hand and compare it to what's in front of them. Every container that isn't on the page and every pipe run that isn't drawn becomes a question about whether the rest of the Plan can be trusted. In New Jersey, EPA Region 2 enforces the federal SPCC rule, and we cover how inspections work in our guide to who enforces SPCC Plans.

The requirement applies to small facilities too. If you're still sorting out whether you need a Plan at all, start with our four steps to figure out if you need an SPCC Plan. New Jersey adds its own layer for major facilities: DPCC and DCR plans under N.J.A.C. 7:1E carry their own content requirements, so a diagram built for SPCC may need additions if the state plans apply to you. Our guide to SPCC Plans in New Jersey covers how the state and federal pieces fit together.

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What Oil Containers and Equipment Belong on the SPCC Facility Diagram?

Start with an inventory, because the diagram can only be as complete as your list of oil. The Plan has to address the type of oil in each fixed container and its storage capacity. Capacity means what the container can hold, not what's in it the day you walk the site, so a half-full 2,000 gallon tank is recorded as 2,000 gallons. Containers of 55 gallons or more count toward the 1,320 gallon aboveground threshold, as we explain in our piece on whether 55-gallon drums count toward SPCC.

Oil shows up in more forms than fuel tanks. Generator sub-base tanks, hydraulic reservoirs, compressor sumps, transformers, and vegetable oil tanks all count. The table shows what each type needs on the diagram.

Whether an underground tank is exempt depends on how it's regulated under the federal UST rules or New Jersey's UST program under N.J.A.C. 7:14B, so confirm that before you write "exempt" on the drawing. Give every container an ID that matches the container table in the Plan, so the reviewer never has to guess which tank you mean.

How Do You Show Transfer Areas and Piping on an SPCC Diagram?

Transfer stations are anywhere oil moves from one place to another: a tank truck delivering diesel, a fueling station, a loading area, or a connection where a hose goes on. The diagram has to include each of them, and it should show where a delivery truck would park, because that tells a reviewer where a hose failure or an overfilled tank would send oil.

The rule also calls for connecting pipes. Draw every run between tanks, fill ports, pumps, and equipment, and mark whether each one is aboveground or buried. Buried piping gets missed most often because nobody can see it, so old as-built drawings and a conversation with whoever maintains the tanks help. Intra-facility gathering lines belong on the drawing too, even where they're exempt from the rest of the rule.

The diagram also supports 40 CFR 112.7(b), which asks the Plan to predict the direction, rate of flow, and total quantity of oil from each type of major equipment failure where experience points to a reasonable chance of one. Flow arrows make that prediction visible.

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How Should Secondary Containment, Drainage, and Nearby Waters Appear on the Diagram?

The rule's diagram sentence doesn't list secondary containment, but the Plan has to address discharge and drainage controls such as secondary containment, and a reviewer expects to find them on the drawing. Outline every dike, berm, curb, drip pan, sump, and containment pallet, and note the containment's size or point to the calculation in the Plan. Our article on how big your SPCC containment needs to be walks through sizing.

Drainage is where a good diagram earns its keep. Mark every storm drain inlet, catch basin, floor drain, separator, ditch, and culvert near your oil, then follow the water. A storm drain next to a fueling area might lead to a municipal storm sewer, or straight to a stream behind the property. Show the outfall, name the receiving water if it has a name, and draw arrows for the direction surface water flows across the site.

Example SPCC Facility Diagram for a New Jersey Site

Here's what these pieces look like together on a simple fictional site. This facility has a main building with drum storage inside, a diked pair of aboveground tanks, a generator, a pad-mounted transformer, a truck unloading area, two storm drains, and a stream along the east property line.

Read it from the containers outward. T1 and T2 sit inside a dike, a fuel supply line runs to the generator, and every container carries an ID that matches the schedule below the map. The fill port at the unloading area connects to T1 by a drawn line. Then follow a spill. The unloading area sits uphill from SD1, the red arrow shows the likely path, and the storm sewer leads to an outfall at the stream. A reviewer can trace oil from its source to the water without reading a paragraph of the Plan.

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How Do You Build an SPCC Facility Diagram From Aerial Imagery or Site Plans?

You don't need CAD skills or a survey crew. A current aerial image or an existing site plan gives you a scaled base, and the rest is careful observation. The process looks like this:

1. Collect a recent aerial image, site plan, or as-built drawing, and confirm its date.
2. Walk the whole site with a printed copy and mark every container, piece of oil-filled equipment, storage area, transfer point, and visible pipe run.
3. Record each container's oil type and capacity from the nameplate or the operator, and assign IDs.
4. Mark storm drains, floor drains, ditches, and low spots, and trace where each one leads.
5. Add nearby waters, flow direction, and the containment around each container.
6. Add a title, date, north arrow, legend, and scale note, then print it in black and white to make sure it still reads.

For the base, free web mapping tools work for many sites, and many county and municipal GIS portals offer parcel and imagery layers. In New Jersey, NJDEP's NJ-GeoWeb includes state aerial imagery and water layers such as surface water classifications, which helps with naming nearby streams. Check the terms of use before you put imagery in a document that gets shared with agencies or lenders. Site plans and as-builts show the design, not always the current condition, so verify them on the ground.

The site walk is the step you can't skip. Aerial images are months or years old, and trees and roofs hide equipment. Look behind buildings, on mechanical pads, and inside maintenance shops, and photograph each container and drain. Remote development works the same way, as we describe in how remote SPCC development works.

Any drawing program can produce a good diagram. We wouldn't hand the job to an AI image generator, because it can't see your site, and we tested whether AI can write an SPCC Plan explains what we found. If your site is simple, you may be able to draw it yourself and skip a consultant for this piece.

What Are the Most Common SPCC Facility Diagram Mistakes?

When we review SPCC Plans written by someone else, the diagram is where we find problems most often. Our list of the most overlooked SPCC requirements covers more, but these are the diagram-specific ones.

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SPCC requirements, Tier I and Tier II plans, PE certification, costs, five-year reviews, and how RMA helps you develop your plan and stay compliant, all in one place.

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When Does an SPCC Facility Diagram Need to Be Updated or Reviewed by a PE?

The diagram has to stay current because the Plan has to match the facility. Under 40 CFR 112.5, you amend the Plan when a change in design, construction, operation, or maintenance materially affects the potential for a discharge. The rule's examples include commissioning or decommissioning containers, moving containers, installing or replacing piping, and construction or demolition that might alter secondary containment. An amendment has to be prepared within six months and implemented as soon as possible, but no later than six months after it's prepared.

The rule also requires a review of the Plan at least once every five years, and the diagram belongs in that review. We explain how it works in SPCC Plan five-year reviews and when to update your SPCC Plan. If a project involves building or demolishing something on site, you'll usually work with your engineer or contractor on the construction approvals, which we don't handle. Our role is the operational side: updating the SPCC Plan and diagram to match the facility once the work is done.

Many Plans also have to be reviewed and certified by a licensed Professional Engineer, and technical amendments generally need that review too unless your Plan qualifies for the self-certification path. The key is having a PE review and approve the SPCC Plan, including whether the diagram matches site conditions. Some firms have a PE on staff, and others work with a trusted outside PE. Our article on when a Professional Engineer is involved covers how that works.

Then put the diagram to work. Walk it with the people who handle oil, and use it during monthly inspections and annual discharge prevention briefings. If your team needs a refresher, our online training library can help.

How Does RMA Help With SPCC Facility Diagrams in New Jersey?

We build SPCC facility diagrams as part of developing and updating SPCC Plans, and we review diagrams in Plans someone else wrote. We're based in New Jersey, so we know how NJDEP and EPA Region 2 treat oil storage here, and a senior member of our team does the work. If your Plan needs Professional Engineer review and approval, we can explain which path applies to your facility.

Cost depends on the number and type of containers, the complexity of the site, and whether the Plan needs PE certification. We've published SPCC Plan pricing from about $2,500 to $15,000, and our SPCC pricing calculator gives you a better estimate. For more background, see everything you need to know about SPCC Plans.

If your facility is simple, you may not need us for this piece, and we'll tell you so. If you'd like a second set of eyes on a diagram or a full Plan, there's no pressure and no obligation. You can call us, send an email, or fill out the form on our website, and you can also reach out to RMA. We'll talk through your site and tell you what we'd do.