Why can the copper in stormwater runoff be treated and removed like it is in sewer water?
• A: Since much of the copper in stormwater runoff is in a dissolved form, the type of treatment technologies that are most commonly retrofitted into storm drain systems—drain inserts that remove trash and other solids—are not effective in removing it. While land-based stormwater runoff treatment systems like infiltration ponds and rain gardens are better at removing copper, widespread installation of these systems would be prohibitively expensive and could be disruptive to established communities, because these systems require significant amounts of land located near storm drain outlets along creeks, rivers, and beaches. It is estimated that the land acquisition and infrastructure costs for Los Angeles County alone could be over $1 billion. The only technically and economically feasible way to reduce copper in these watersheds is to remove it at its source – vehicle brake pads.
