How many drinking water plants of the city of Toronto have?

F.J. Horgan, R.C. Harris, Island WTP and R.L. Clark are the plant names.

An evaluation of the emergency gaseous control system at each of the four (4) water treatment plants was conducted to ensure compliance with all Provincial and Federal guidelines.
In Ontario, all environmental discharge sources are required to comply with the Point of Impingement standards of Regulation 346 (Environmental Protection Act) and Regulation 419/05 (Air Pollution local air quality guidelines); emergency scrubber design requirements, including allowable stack discharge concentrations, are not implicitly stated.

F.J. Horgan, R.C. Harris and the Island WTP are equipped with emergency dry scrubbers designed to handle the release of a 1-tonne gas cylinder whereas R.L. Clark is equipped with a 2-tonne emergency dry scrubber.

All four (4) dry scrubber units were designed based on the American Uniform Fire Code (UFC) which states that the scrubbers shall be capable of adsorbing the contents of the single largest vessel (1-tonne of chlorine gas or sulphur dioxide) within 30 minutes, however, Environment Canada recognizes the worst case scenario of a gaseous leak to be the entire quantity of an interconnected system being released if individual tonners cannot be isolated.

The fours (4) WTPs typically have two (2) or three (3) tonners/scales connected to a common header. With the exception of the Clark WTP, the existing scrubber systems at the remaining three (3) plants do not have the capacity to handle the accidental worst case scenario.
Based on these findings, the City is embarking on a comprehensive project to upgrade the gaseous chemical systems including, but not limited to the following:

a. Review condition of existing gaseous chemical system
b. Review existing emergency gas scrubber blower size with respect to UFC requirements.
c. Provide remotely actuated isolation valves for connected chlorine and sulphur dioxide tonners.
d. Provide a manually operated drum scrubber to scrub minor chlorine and sulphur dioxide gas releases during maintenance activities in both the gaseous storage and equipment rooms, except at the Horgan WTP.

e. Provide SCADA integration and control for emergency gas scrubber for manual and automatic initiation.

f. Conduct dispersion modelling to determine the maximum allowable chlorine and sulphur dioxide concentrations at the exhaust stack of each facility and to assess evacuation zones for Environmental Emergency regulatory compliance.

g. Other miscellaneous upgrades, as described in this RFP.