NZ818070B2 - Crossflow settling devices and methods of use - Google Patents

Abstract

stormwater treatment device (100) comprising a housing (105), an inlet (110) that receives stormwater including suspended sediment into an inlet chamber of the housing, a treatment chamber and settlement storage area (120), a bypass channel, and an outlet (115) that discharges the stormwater from an outlet chamber of the housing. The inlet chamber is defined by a first portion of the housing wall and a front baffle (130), the front baffle extending vertically from the floor of the housing. The outlet chamber is defined by a rear baffle (125), a second portion of the housing wall, and a short circuit prevention plate (165). The treatment chamber and settlement storage area (120) is defined by the front baffle (130), a third portion of the housing wall, the rear baffle (125), and the short circuit prevention plate (165). The treatment chamber and settlement storage area includes a crossflow settling device having a treatment channel defined by the front baffle (130), the rear baffle (125), and pairs of angled plates (135) disposed between the front baffle (130) and the rear baffle (125). A first pair of angled plates disposed on a first side of a centerline of the housing, and a second pair of angled plates disposed on a second side of the centerline, the first pair of angled plates and the second pair of angled plates diverging at an angle. The front baffle (130) has a treatment channel opening (not shown) and the rear baffle (125) has a treatment channel outlet (160). The bypass channel comprises an inlet weir (140), an outlet weir (145), and a pair of bypass channel walls (155). An elevation of a top of the inlet weir is the same as the elevation of the outlet weir between the bypass channel walls (150) but below an elevation of the top of the outlet weir outside the bypass channel, and an elevation of the bypass channel walls. Under high flow, stormwater flows over the inlet weir and through the bypass channel, thereby bypassing the treatment chamber and settlement storage area (120). Under normal flow, stormwater flows into the inlet and into the inlet chamber, into the treatment channel via the treatment channel opening (not shown), into the outlet chamber via the treatment channel outlet (160) in a crossflow pattern causing the sediment to fall out of suspension, and out of the crossflow settling device through openings (180) at the bottom of the pairs of angled plates. The invention provides a first opportunity to remove suspended contaminants from stormwater before stormwater enters the sewer.

Claims (4)

1. A stormwater treatment device, comprising: a housing having a floor and a wall; an inlet formed in the wall that receives stormwater including suspended sediment into an inlet chamber of the housing, the inlet chamber defined by a first portion of the wall and a front baffle, the front baffle extending vertically from the floor of the housing; an outlet formed in the wall that discharges the stormwater from an outlet chamber of the housing, the outlet chamber defined by a rear baffle, a second portion of the wall, and a short circuit prevention plate; a treatment chamber and settlement storage area defined by the front baffle, a third portion of the wall, the rear baffle, and the short circuit prevention plate and having a crossflow settling device disposed therein, the crossflow settling device having a treatment channel defined by the front baffle, the rear baffle, and a first pair of angled plates disposed on a first side of a centerline of the housing, and a second pair of angled plates disposed on a second side of the centerline, the first pair of angled plates and the second pair of angled plates diverging at an angle, the first pair of angled plates and the second pair of angled plates disposed between the front baffle and the rear baffle, the front baffle having a treatment channel opening and the rear baffle having a treatment channel outlet; and a bypass channel comprising an inlet weir, an outlet weir, and a pair of bypass channel walls, wherein an elevation of a top of the inlet weir is the same as the elevation of the outlet weir between the bypass channel walls but below an elevation of the top of the outlet weir, outside the bypass channel, and an elevation of the bypass channel walls, wherein the bypass channel receives a flow over the inlet weir when a flow exceeds a limit, thereby bypassing the treatment chamber and settlement storage area; wherein, under normal flow, the stormwater flows into the inlet and into the inlet chamber, into the treatment channel via the treatment channel opening, into the outlet chamber via the treatment channel outlet, wherein the stormwater flows in a crossflow pattern causing the sediment to fall out of suspension, and out of the crossflow settling device through openings at a bottom of the pairs of angled plates.

2. The stormwater treatment device of claim 1, wherein under high flow, the stormwater flows over the inlet weir and either into the bypass channel and over a notch in the outlet weir and into the outlet chamber, and out of the housing via the outlet or into a floatables retention zone between the bypass channel walls and a third portion of the wall.

3. The stormwater treatment device of claim 2, wherein under a very high flow, floatables overflow the outlet weir and the pair of bypass walls into the outlet chamber.

4. The stormwater treatment device of claim 1, wherein the first pair of angled plates and the second pair of angled plates are provided at an angle of about