BMP DEEP DIVE VOL. 1

TARGETING METALS BEFORE THE STORM

Stormwater runoff doesn’t just carry visible pollutants like trash, oil, or sediment, it also transports invisible threats: dissolved metals. For industrial facilities in California, these metals are one of the most common causes of stormwater compliance violations.

Copper, zinc, and other trace metals dissolve in water and can easily exceed permit thresholds, leading to regulatory action, costly treatment, and potential fines. The good news? With the right Best Management Practices (BMPs), you can get ahead of dissolved metals before they become a compliance killer.

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WHAT ARE DISSOLVED METALS?

Dissolved metals are microscopic particles of metals that are soluble in water. Unlike solids you can filter out easily, dissolved metals move freely with stormwater.

Common dissolved metals in industrial runoff:

• Copper – often from brake dust, roofing, or treated wood.
• Zinc – from galvanized steel, tires, or downspouts.
• Iron – from machinery, rusting surfaces, or soil.
• Lead – from batteries, paint, or old infrastructure.

Even at trace levels, these pollutants can harm aquatic life and trigger exceedances under the Industrial General Permit (IGP).

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WHY METALS MATTER FOR INDUSTRIAL ​STORMWATER COMPLIANCE

Regulators set strict Numeric Action Levels (NALs) for metals like copper and zinc. If your sampling results exceed these levels, you’re required to take additional actions such as:

• Preparing Exceedance Response Action (ERA) reports
• Implementing advanced treatment BMPs
• Facing increased regulatory scrutiny
  

In California, copper and zinc are the top two dissolved metals responsible for ERA reports under the IGP. Staying proactive with BMPs saves both compliance headaches and costs.

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BEST BMPS FOR REDUCING METALS IN RUNOFF

Filter Media Socks: Media socks filled with engineered absorbents can reduce dissolved copper and zinc before they leave your facility. Easy to deploy around drains and in flow paths.

Flocculants: Solid flocculants bind with metals, causing them to clump together and settle out of stormwater. This simple treatment step can dramatically lower dissolved concentrations.

pH Adjustment Solutions: Since metal solubility is pH-dependent, adjusting stormwater pH can reduce dissolved copper and zinc levels. This works well alongside filtration and flocculants.

Pro tip: Combining BMPs is often the most effective way to meet permit requirements and keep stormwater in compliance.

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STORMWATER TREATMENT SYSTEMS FOR DISSOLVED METALS

For facilities dealing with persistent metal exceedances, advanced stormwater treatment systems can provide a reliable, long-term solution.

These systems are designed to:

• Remove dissolved metals such as copper, zinc, and lead before discharge
• Handle high flow volumes from industrial sites
• Integrate with existing BMPs like filter socks or flocculants
• Ensure consistent compliance under state and federal regulations
  

Frog Environmental offers customized treatment system solutions, including filtration units, settling tanks, and modular treatment setups tailored to your facility’s specific needs.

Pairing BMPs with a treatment system provides a multi-layered approach to controlling dissolved metals, helping industrial facilities stay ahead of stormwater compliance requirements.

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REAL-WORLD SUCCESS: ALLAN CO.

Frog Environmental partnered with Allan Co., a California-based industrial facility, to address recurring stormwater exceedances caused by dissolved metals and other pollutants.

By implementing a tailored combination of BMPs and upgrades to their existing treatment system, including:

• MetalPROOF™ media socks
• Solid flocculants

the facility achieved an impressive 96% reduction in pollutants, bringing their stormwater runoff fully into compliance with state regulations.

This case study demonstrates the real-world effectiveness of BMPs in controlling dissolved metals and other stormwater pollutants.

For full details, read the original case study: How Frog Environmental Helped Allan Co. Achieve 96% Pollutant Removal

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FAQ: ARE DISSOLVED METALS THE SAME AS HEAVY METALS?

Not exactly.

• Heavy metals is a broad term for toxic metals like copper, zinc, lead, and cadmium that can appear in stormwater.
• These metals can exist in two forms:
  • Particulate metals – attached to soil or sediment particles (easier to capture with basic filtration).
  • Dissolved metals – microscopic and soluble in water (harder to remove, more harmful to aquatic life).
• Dissolved metals are a subset of heavy metals. They’re the form most likely to cause permit exceedances and require advanced BMPs or treatment systems to control.
  

In California’s Industrial General Permit (IGP), industrial facilities are required to monitor for certain metals depending on their industry type. While several metals can be regulated, dissolved copper and dissolved zinc are by far the most common pollutants driving compliance challenges across the state.

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HOW TO STAY AHEAD OF METAL EXCEEDANCES

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GET METAL REMOVING BMPS TODAY

Frog Environmental provides field-tested solutions for dissolved metals, including:

• Media Socks
• Solid Flocculants
• Rain barrel polishers and more.