Patent ID: 8147688

Claim:
A stormwater detention system, comprising: a containment row buried in water permeable media, the containment row including: one or more open-bottom chambers, and a substantially water impermeable membrane covering at least the open bottom of the chambers, the water impermeable membrane preventing water in the containment row from exiting directly into the media through the membrane; a detention row buried in the water permeable media, the detention row including one or more open-bottom chambers, the detention row configured such that water can exit the bottom of the detention row directly into the media; a pipe system connecting the containment row to the detention row, the pipe system configured such that a substantial portion of water that enters the containment row later exits the containment row and travels to the detention row without first passing into the water permeable media; wherein the pipe system includes a diversion structure with an overflow weir, such that water up to a certain level within the diversion structure is diverted to the containment row, but water overflowing the weir bypasses the containment row to a downstream side of the diversion structure, and wherein a pipe manifold connects the downstream side of the diversion structure to the detention row; wherein the weir includes a drain down path, such that water that enters the containment chamber eventually passes back into the diversion structure, and passes out the drain down path to the pipe manifold for delivery to the detention row.