Patent ID: 8333895

Claim:
A pond for receiving and flowing an inflow of contaminated water therethrough, the pond comprising: a pond basin for substantially containing the inflow of contaminated water, the pond having a pond volume comprising at least a resident volume being initially substantially quiescent and having a large rotational inertia prior to receiving the inflow of contaminated water; an inlet for introducing the inflow of contaminated water to the pond substantially tangential to a periphery of the pond, thereto; and an outlet positioned at about a centre of the pond for discharging at least a portion of the pond volume therethrough, the outlet being at an elevation above a bottom of the pond for maintaining the at least a resident volume in the pond, the discharging of the at least a portion of the pond volume therefrom and the inflow of contaminated water at the inlet causing the pond volume to flow in a spiral flow path from the inlet to the outlet, wherein at least a portion of the resident volume is directed to the outlet, ahead of the inflow of contaminated water, a hydraulic retention time of the contaminated water in the pond being sufficiently long so as to permit removal of at least a portion of the contaminants therein and to discharge a substantially clarified water stream at the central outlet.