Apparatus for separating particulate from stormwater

1. A separation system for separating particulate from liquid, the system comprising:

a) a tank including an inlet for receiving liquid therein and an outlet for transferring liquid out of the tank;

b) a storage chamber forming part of the tank, the storage chamber including a bottom and interior sidewalls, an inlet and an outlet;

c) a bypass extending through the tank, wherein the bypass is arranged to receive liquid from the tank inlet, to transfer liquid into the storage chamber via the storage chamber inlet and to receive liquid from the storage chamber via the storage chamber outlet;

d) a weir configured to direct liquid from the tank inlet to the storage chamber under relatively low flows and under relatively high flows to divert one portion of liquid from the tank inlet to the storage chamber and to allow another portion of liquid to flow directly through the bypass from the tank inlet to the tank outlet without entering the storage chamber;

wherein liquid entering the storage chamber is directed to produce a rotational liquid flow, as viewed from the top, within the storage chamber, which rotational liquid flow progresses downwardly within the storage chamber along the periphery of the storage chamber, and a storage chamber outlet port opening is located centrally within the storage chamber and at an elevation that is at or below the bottom of the bypass, and wherein flow in a region of the storage chamber below the storage chamber outlet port opening is substantially unobstructed, and wherein flow into the storage chamber outlet port opening is upward and the storage chamber outlet port opening faces downward,

wherein the bypass comprises an elongated U-shaped structure that is open at the top, ends of the U-shaped structure supported in respective U-shaped frames that are mounted to sidewalls of the tank.

2. The separation system of claim 1 wherein the elevation of the bottom of the bypass is X and the elevation of the storage chamber outlet port opening is between ½ X and X, wherein X is a distance measured from the bottom of the storage chamber.

3. The separation system of claim 2 wherein the elevation of the storage chamber outlet port opening is between ⅔ X and X.

4. The separation system of claim 1 wherein both a primary circulation pattern and a secondary meridional circulation pattern are created within the storage chamber, the secondary circulation pattern causes an upward flow of liquid in a central region of the storage chamber.

5. The separation system of claim 1 wherein the bypass is formed by a pipe, trough or other structure extending from the tank inlet to the tank outlet.

6. The separation system of claim 5 wherein the bypass extends substantially linearly across a diameter of the tank, the storage chamber is substantially cylindrical and the bottom is closed.

7. The separation system of claim 6 wherein storage chamber inlet includes an L-shaped drop pipe structure connected with the bypass, the storage chamber outlet comprises a linear drop pipe structure having the downwardly facing storage chamber outlet port opening at its lower end.

8. The separation system of claim 1 wherein the tank inlet is in a top wall of the tank.

9. The separation system of claim 8 wherein a flow directing structure is positioned in the top wall of the tank and includes an opening to direct incoming stormwater into the bypass on a side of the weir that includes the storage chamber inlet.

10. The separation system of claim 1 wherein the storage chamber inlet is formed in a lower wall of the bypass, and a storage chamber spillover inlet is provided in a sidewall of the bypass at a height lower than a top of the weir.

11. A separation system for separating particulate from liquid, the system comprising:

a tank including an inlet for receiving liquid therein and an outlet for transferring liquid out of the tank, a storage chamber within the tank, water entering the tank is directed to produce a rotational liquid flow, as viewed from the top, within the storage chamber, which rotational liquid flow progresses downwardly within the storage chamber along the periphery of the storage chamber, and a downwardly facing storage chamber outlet port opening for a flow path leading from the storage chamber to the tank outlet is located centrally within the storage chamber and at an elevation that is at or below an invert of the outlet of the tank, and wherein flow into the storage chamber outlet port opening is in an upward direction;

a bypass within the tank, the bypass receiving liquid from the tank inlet, a storage chamber inlet for delivering liquid from the bypass into the storage chamber, a storage chamber outlet for delivering liquid from the storage chamber back to the bypass, a weir positioned in the bypass between the storage chamber inlet and the storage chamber outlet, the storage chamber outlet port opening associated with the storage chamber outlet, wherein the bypass comprises an elongated U-shaped structure that is open at the top along a full length of the bypass and the U-shaped structure extends linearly across a diameter of the tank, ends of the U-shaped structure supported in respective U-shaped frames that are mounted to sidewalls of the tank.

12. The separation system of claim 11 wherein the storage chamber outlet port opening is located between ½ X and X, wherein X is a distance measured from the bottom of the storage chamber.

13. The separation system of claim 12 wherein the tank outlet is located in a tank sidewall that partially defines the storage chamber, liquid entering the storage chamber outlet port opening in the upward direction subsequently turns to exit the tank outlet.

14. The separation system of claim 13 wherein both a primary circulation pattern and a secondary circulation pattern are created within the storage chamber, the secondary meridional circulation pattern causes an upward flow of liquid in a central region of the storage chamber, the storage chamber is substantially a right circular cylinder shape with a substantially vertical axis and has a closed bottom.

15. The separation system of claim 14 wherein the tank inlet is in a top wall of the tank, a flow directing structure is positioned in the top wall of the tank and includes an opening to direct incoming stormwater into the bypass on a side of the weir that includes the storage chamber inlet.

16. A separation system for separating particulate from a liquid, the system comprising:

a) a tank including an inlet for receiving the liquid therein and an outlet for transferring the liquid out of the tank;

b) a storage chamber forming part of the tank, the storage chamber including a bottom and interior sidewalls, an inlet and an outlet;

c) a bypass extending through the tank, wherein the bypass is arranged to receive the liquid from the tank inlet, to transfer the liquid into the storage chamber inlet and to receive the liquid from the storage chamber outlet, wherein the bypass comprises an elongated U-shaped structure that is open at the top along a full length of the bypass and the U-shaped structure extends linearly across a diameter of the tank, ends of the U-shaped structure supported in respective U-shaped frames that are mounted to sidewalls of the tank; and

d) a weir positioned in the bypass between the storage chamber inlet and the storage chamber outlet, wherein the weir is configured to divert liquid from the tank inlet to the storage chamber under relatively low liquid flows, and under relatively high liquid flows to divert one portion of the liquid from the tank inlet to the storage chamber and to allow the remaining portion of the liquid to flow directly through the bypass from the tank inlet to the tank outlet;

wherein the storage chamber inlet is formed by a tubular structure that extends downwardly from the bypass into the storage chamber and configured to produce a rotational liquid flow, as viewed from the top, within the storage chamber, and about a center axis of the storage chamber, including a radially outer and downward rotational flow and a radially inner and upward rotational flow;

wherein the storage chamber outlet includes a tubular structure that extends downwardly from the bypass into the storage chamber and having a downwardly facing outlet port opening through which the center axis of the storage chamber extends, the downwardly facing outlet port opening receiving upward flow of liquid from the storage chamber; and

and wherein flow in a region of the storage chamber below the downwardly facing outlet port is substantially unobstructed.

17. The system as claimed in claim 16 wherein the weir has a wall height such that its top exceeds the height of the top of the tank inlet.

18. A separation system for separating particulate from a liquid, the system comprising:

a) a tank including an inlet for receiving the liquid therein and an outlet for transferring the liquid out of the tank;

b) a storage chamber forming part of the tank, the storage chamber including a bottom and interior sidewalls defining a right circular cylinder shape with a substantially vertical center axis, an inlet and an outlet;

wherein the storage chamber inlet is configured to produce a rotational liquid flow, as viewed from the top, within the storage chamber, and about the center axis of the storage chamber, including a radially outer and downward rotational flow and a radially inner and upward rotational flow; and

wherein the storage chamber outlet includes a downwardly facing outlet port opening through which the center axis of the storage chamber extends, the downwardly facing outlet port opening receiving upward flow of liquid from the storage chamber;

c) a bypass within the tank and extending linearly across the tank, the bypass receiving liquid from the tank inlet, the storage chamber inlet positioned for delivering liquid from the bypass into the storage chamber, the storage chamber outlet positioned for delivering liquid from the storage chamber back to the bypass, a weir positioned in the bypass between the storage chamber inlet and the storage chamber outlet, a storage chamber spillover inlet positioned along the bypass to allow floatables in the bypass to enter the storage chamber without having to travel through the storage chamber inlet and before such floatables pass over the weir toward the tank outlet, and a head equalization baffle positioned in the bypass between the storage chamber outlet and the tank outlet.

19. The system as claimed in claim 18 wherein the storage chamber inlet includes a first conduit connected to a second conduit, wherein the second conduit is angled with respect to the first conduit.

20. The system as claimed in claim 19 wherein the first conduit is arranged to be either (i) at or near perpendicular to a plane defined by the bottom of the storage chamber or (ii) at or near parallel to the plane defined by the bottom of the storage chamber.

21. A separation system for separating particulate from a liquid, the system comprising:

a) a tank including an inlet for receiving the liquid therein and an outlet for transferring the liquid out of the tank;

b) a storage chamber forming part of the tank, the storage chamber including a bottom and interior sidewalls, an inlet and an outlet;

c) a bypass within the tank, the bypass receiving liquid from the tank inlet, the tank inlet delivering liquid to the bypass, the storage chamber inlet positioned for delivering liquid from the bypass into the storage chamber, the storage chamber outlet positioned for delivering liquid from the storage chamber back to the bypass, a weir positioned in the bypass between the storage chamber inlet and the storage chamber outlet, the storage chamber outlet includes a downwardly facing outlet port;

wherein the bypass comprises an elongated U-shaped structure that is open at the top along a full length of the bypass and the U-shaped structure extends linearly across a diameter of the tank, ends of the U-shaped structure supported in respective U-shaped frames that are mounted to sidewalls of the tank.