In order to protect the wastewater treatment plant’s ability to continue treating wastewater during an extreme rainstorm, some of the excess flow (stormwater and sewage) that reaches the plant may need to be diverted around one of the plant’s many treatment processes.

Because the bypass process happens during storm events, the water is mostly rain water (often a ratio of four or five parts rain to one part sewage). All bypass flow continues to goes through:

  • screening
  • grit removal
  • primary treatment
  • phosphorous removal
  • disinfection

Bypassses can occur at the Ashbridges Bay and Humber Wastewater Treatment Plants, as these plants service older areas of the city with combined sewers (one pipe that carries stormwater and sewage).

The bypass reports are updated monthly, within 30 days of the end of each month.

Date Duration (hrs)

Volume (m3)

Reason
January 12 4.25 90,709 Excessive Stormwater Flow
April 16-17 16.95 729,819 Excessive Stormwater Flow
June 24 4.1 99,410 Excessive Stormwater Flow
August 7-8 3.72 127,350 Excessive Stormwater Flow
November 1-2 7.55 244,510 Excessive Stormwater Flow
November 26 9.86 264,440 Excessive Stormwater Flow

Date Duration (hrs) Volume (m3) Reason
January 11-12  17.6 total (4.7 active)*  13,249 Excessive Stormwater Flow
February 20 14.9 total (7.6 active)* 14,131 Excessive Stormwater Flow
February 21 3.3 956 Excessive Stormwater Flow
April 3-4 6.5 31,962 Excessive Stormwater Flow
April 16-18 46.5 332,131 Excessive Stormwater Flow
April 25 4.6 142,65 Excessive Stormwater Flow
June 13 0.75 1,200 Excessive Stormwater Flow
June 24 3.5 23,772 Excessive Stormwater Flow
July 5 1.5 8,983 Excessive Stormwater Flow
July 22 0.5 1,377 Excessive Stormwater Flow
July 24 0.6 325 Excessive Stormwater Flow
August 6 1.8 11,566 Excessive Stormwater Flow
August 7-8 5.7 35,581 Excessive Stormwater Flow
August 17 0.8 2,207 Excessive Stormwater Flow
August 21 3.25 13,499 Excessive Stormwater Flow
September 10 2.7 1,428 Excessive Stormwater Flow
October 2 0.2 418 Excessive Stormwater Flow
November 1-2 8.75 43,713 Excessive Stormwater Flow
November 26 2.5 13,736 Excessive Stormwater Flow

 

*More than one bypass occurred over this total amount of time due to one rain event. Active hours denote the time the bypass process was activated.

Date Duration (hrs) Volume (m3) Reason
January 10-11 2.08 40,378 Excessive Storm
January 12 2.97 75,740 Excessive Storm
April 6 6.4 210,338 Excessive Storm
May 1 5 192,317 Excessive Storm
May 25 10.55 405,789 Excessive Storm
June 23 9.8 479,469 Excessive Storm
July 20 4.25 165,940 Excessive Storm
Total 41.05 1,569,971

Date Duration (hrs) Volume (m3) Reason
January 10 6.5 44,377 Excessive Storm
January 12 2.9 14,878 Excessive Storm
February 25 2.2 22,611 Excessive Storm
March 1 7.3 34,893 Excessive Storm
March 25 0.5 329 Excessive Storm
April 4 3 38,176 Excessive Storm
April 6 13.3 78,867 Excessive Storm
April 30 1.75 10,293 Excessive Storm
May 1 11.8 105,900 Excessive Storm
May 4-6 32.5 512,834 Excessive Storm
May 25 12.5 87,152 Excessive Storm
June 17 2 6,751 Excessive Storm
June 23 10.6 78,031 Excessive Storm
June 30 0.75 412 Excessive Storm
July 20 4.1 6,751 Excessive Storm
August 4 3.5 13,542 Excessive Storm
Total 115.2 1,055,797

Bypass information can also be found in the Ashbridges Bay and Humber Wastewater Treatment Plant Annual Reports.