Abstract: A pollution trap for storm-water runoff includes a filter-box assembly that provides for top-down maintenance. The filter-box assembly includes at least one filter container, a filter-container support, and a peripheral seal, so the filter container can be lifted from and lowered into the trap from above. The filter container includes sidewalls forming an open bottom and top, a bottom filter support, and a top filter retainer, with the container receiving a stack of intelligently-selected filters supported on the filter support and kept in the container by the top filter retainer. An optional adjustable hold-down assembly holds down the top filter retainer and the underlying filters. The filter-container support holds the filter container up off the trap floor so the storm-water can up-flow through it. And the seal is interposed peripherally between the filter container and the filter-container support so the storm-water cannot flow around the filter container.

Abstract: A pollution trap for storm-water runoff includes a filter-box assembly that provides for top-down maintenance. The filter-box assembly includes at least one filter container, a filter-container support, and a peripheral seal, so the filter container can be lifted from and lowered into the trap from above. The filter container includes sidewalls forming an open bottom and top, a bottom filter support, and a top filter retainer, with the container receiving a stack of intelligently-selected filters supported on the filter support and kept in the container by the top filter retainer. An optional adjustable hold-down assembly holds down the top filter retainer and the underlying filters. The filter-container support holds the filter container up off the trap floor so the storm-water can up-flow through it. And the seal is interposed peripherally between the filter container and the filter-container support so the storm-water cannot flow around the filter container.