| Intake |
| The Orillia Water Filtration Plant has two intakes. The primary intake has a nominal diameter of 1000 mm, and a total length of 374 metres. The second intake has a nominal diameter of 600 mm, and a length of 84.6 metres. This intake is to be used in the event of an emergency.
The intake operates by gravity flow. Chlorine is applied to the intake bell of the 1000 mm diameter intake in Lake Couchiching. Raw water is sampled at the intake bell and pumped by sample pump to the plant laboratory.
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| Raw Water Screens |
| The traveling water screen is the unit primarily used to prevent coarse materials in the raw water from entering the low-lift suction well. When this unit is taken out of service, the bypass screen can be used. |
| Low Lift Pumping Stations |
| Screened, raw water is pumped from the low lift pump well to the raw water discharge header and then to the plant flocculation tanks. Coagulation is added at a motorized inline blender, located on the discharge header of the low lift pumps. The low lift pumping station is equipped with four pumps. |
| Flocculation |
| The plant is equipped with three passes of two-stage hydraulic flocculation. Flocculation is a process that clarifies the water. Clarifying means removing turbidity (e.g., suspended sediment or fine particles) and colours so that the water is clear and colourless. The process of flocculation basically involves causing a precipitate to form in the water by entrapping the small particles, which then stick together, or coagulate, to form bigger particles. The coagulated precipitate takes most of the suspended particles out of the water, which can then be removed through simple physical methods such as filtration. |
| Filtration |
| There are two types of filters in the Orillia Water Filtration Plant. The original Filters 1 and 2 are gravity flow with a dual media consisting of granular activated carbon and sand with a gravel support and clay tile under drains. Filters 1 and 2 use water surface wash agitators to agitate the media during the low water wash phase of the wash cycle. Filters 3 and 4 are gravity flow with a granular activated carbon and sand media with strainer under drains capable of an air scour during backwash.
The objective of filtration is to remove floc particulate matter from the water prior to disinfection to optimize the disinfection processes.
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| Backwash |
| The backwash system uses treated water from the clearwells for backwashing the filters. Two vertical turbine pumps are provided for backwash purposes. The objective of the backwash system is to provide an adequate backwash to minimize filtered water effluent turbidity, maximize solids carrying capacity of the media, and, consequently, maximize filter run time. |
| Post-Filtration Chlorine Contact Tanks |
| Filtered water is collected in a filtered water effluent header, directed through a common point for chlorine addition and directed into a two-stage baffled chlorine contact tank. The two stages are identified as Chlorine Contact Tank 1 and Chlorine Contact Tank 2. The objective of the chlorine tanks is to provide a defined period of contact between the filtered water and the chemical disinfectant, chlorine. The tanks were designed to provide for three-log inactivation of viruses, which represents the level of virus inactivation appropriate for the City of Orillia's water source. |
| On-Site Reservoir Storage |
| The clearwell consists of two cells, each with an approximate capacity of 1500 m³. The clearwell provides buffering capacity for changes to and differences in high lift pumping and filtration rates. The clearwell also provides a supply of water for filter backwashing. All of the water discharged from the chlorine tanks passes to the clearwell.
Three high-lift pumps and one backwash pump draw from each cell, ensuring a continued water supply to each pressure zone in the distribution system and for backwash operations.
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| High Lift Pumping Station |
| The high lift pumps discharge treats water from the clearwells into two pressure zones in the distribution system. Each zone is supplied by three pumps with the option of obtaining water from either cell of the clearwell. |
| Ultraviolet Disinfection System |
| The plant is equipped with three ultraviolet (UV) disinfection reactors located on the high lift pump discharge. |
| Chlorination System |
| The chlorination system consists of five chlorinators. The primary function of the chlorination system is to supply chlorine to the various application points for chemical disinfection of viruses. Chlorine can be used as a backup to the UV disinfection system in the event of a partial or complete failure of that system.
Pre-chlorine is typically added to the intake diffuser in proportion to the raw water to protect against zebra mussels during the summer and fall months.
Post-chlorine is added before the filtered water enters the chlorine contact tanks and is considered the primary application point for the chemical in the plant disinfection system.
Top up of the chlorine residual at the Zone 1 and 2 high lift headers may be necessary to ensure an optimal level for maintenance of residual in the water distribution system. Chlorine is applied at these final locations in proportion to the discharge flow into the zone.
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| Groundwater Wells |
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In 2006, the West Orillia Well was commissioned and began producing water to augment the Zone 2 distribution system. The Well House contains one deep well pump that feeds the system using either pressure or reservoir tower levels. The well water is disinfected using chlorine in the form of sodium hypochlorite and is pumped to the distribution system. In the event of a hydro power failure, the well house is supported by a standby diesel generator. |
| West Orillia Well |
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Well #1
(Jarvis Street) |
Well #2
(Jarvis Street) |
Well #1 and Well #2 are located within 160 metres of Lake Couchiching and are approximately 170 metres apart. The wells were originally constructed in 1940 and were found to have increased levels of trichloroethylene (TCE) and tetrachloroethylene (PCE). They were removed from service in 2001 and put back in production in 2008 after construction of a new groundwater treatment building that houses an air stripping process for removal of the TCE and PCE. The process blows air through weir troughs to diffuse the TCE and PCE from the water.
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| Water Distribution System |
| Construction of the City's water distribution system commenced in 1872 and now consists of more than 162 kilometres of watermains. The watermains range in size from 50 mm to 600 mm and pipe materials consist of cast iron, ductile iron, PVC and concrete.
There are three water storage reservoirs in operation. The Harvie Hill reservoir was constructed in 1968 and its primary service area is Pressure Zone 2, but it can also be used to supplement Pressure Zone 1 if required. There are two reservoirs on Rosemary Road that essentially operate as one and service Pressure Zone 1.
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Harvie Hill Reservoir
(Highway 11) |
Rosemary Road Reservoir |
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| Boil Water Advisory |
| A boil water advisory is based on information other than bacteriological examination indicating that the water is not safe to drink (e.g., the lack or absence of disinfection residual in the drinking water). A boil water advisory may also be based on bacteriological (microbial) examination, including the finding of bacteria or parasites or may follow the occurrence of an outbreak of illness in the community that has been linked to consumption of the water. |
