Joint Utility Board Sewage Treatment Plant: History, Treatment Process, and Performance Overview ________________________________________________________________ Presentation for: Saanich Peninsula Inlet Protection Society By: Clay Reitsma, M.Eng., P.Eng. Senior Manager, Engineering District of North Cowichan March 14, 2019

Presentation Outline Treatment Process Description Performance of Treatment Facility Q&A ________________________________________________________________

Treatment Process & Flow Path Cell 1 Cell 5B Cell 2 Cell 5A Cell 6 ________________________________________________________________ Cell 4 Cell 3

Treatment Unit Processes The treatment system has many different components that work together to treat the wastewater. They include: Screening Removes larger inorganic material (plastics, rocks). Degritting Removes heavier/finer inorganic material (sand). Oxidation Converts organics to micro-organisms for subsequent removal by sedimentation. Settling Settles out micro-organisms. Alum Addition Removes phosphorus. Chlorination Kills bacteria and viruses in the process water. De-Chlorination Removes residual chlorine byproducts from the effluent prior to discharge to the river. ________________________________________________________________

Treatment Unit Processes Cell 2 Cell 1 Cell 3 Cell 4 Cell 5A Cell 5B Cell 6 Screening & Degritting Oxidation Oxidation / Settling Settling Alum Addition Disinfection De-Chlorination ________________________________________________________________

Treatment Unit Processes: Screening Removes larger inorganic material (plastics, rocks). ________________________________________________________________ Fine perforated plate screen screens out larger inorganic material. Screened wastewater passes through to the degritting process. Captured solids (screenings) are washed, pressed/dewatered, and conveyed into a covered holding container. A fan draws odourous air from the system and scrubs it through a biofilter.

Treatment Unit Processes: Degritting Removes heavier/finer inorganic material (sand). ________________________________________________________________ Total of four grit channels. Flow velocity is maintained at 1 ft/sec to allow heavier/finer inorganics to settle. Grit is removed from the channels monthly and deposited into Cell 6.

Treatment Unit Processes: Biological Oxidation (Cell 1) Converts organics to micro-organisms. Cell 2 Cell 1 Cell 3 Cell 4 Cell 5A/5B Cell 1 Cell 2 ________________________________________________________________ Wastewater flows from the grit channels to Cell 1. Purpose is to convert organic matter (which exerts an oxygen demand in receiving waters) to micro-organisms (which will settle in subsequent ponds). By settling out the micro-organisms in subsequent cells, the organic matter is removed from the liquid.

Treatment Unit Processes: Biological Oxidation (Cell 1) Converts organics to micro-organisms. ________________________________________________________________ Air is provided to mix the water and bring micro-organisms in contact with their food (organic matter). Air is also provided as a source of oxygen. The micro-organisms need oxygen to survive. Air diffusers hang from flexible laterals that float on the surface of Cell 1. Flexible laterals are designed to move from side to side to maximize mixing. This significantly reduces aeration costs.

Treatment Unit Processes: Biological Oxidation (Cell 1) Converts organics to micro-organisms. ________________________________________________________________ Air is provided by two 150 kW blowers . One blower is a standby unit. There is provisions for a third blower in the future when additional aeration diffusers are added (can add 50% more diffusers). The blowers take air from the atmosphere, pressurize it and send it to the diffusers that are submerged in Cell 1.

Treatment Unit Processes: Biological Oxidation (Cell 1) Converts organics to micro-organisms. ________________________________________________________________ The diffusers have tiny holes that release small bubbles. The bubbles mix the water. The bubbles also dissolve into the water and provide oxygen for the micro-organisms. This is a fine bubble system. More efficient for transferring oxygen to water.

Treatment Unit Processes: Settling (Cells 2 & 3) Settles out micro-organisms that were grown in Cell 1. Cell 2 Cell 1 Cell 3 Cell 4 Cell 5A/5B ________________________________________________________________ Process water from Cell 1 flows to Cells 2 and 3. After organics are converted to micro-organisms, the organics must be extracted from the process water to reduce CBOD5 and TSS in the effluent. Since the micro-organisms are heavier than water they settle out. Every 10 to 15 years the settled material is removed and deposited in Cell 6.

Treatment Unit Processes: Alum Addition Removes phosphorus. Cell 1 Cell 5A/5B Cell 2 Alum Storage & Pumps Cell 3 Cell 4 Flash Mix / Floc Channel Alum Storage ________________________________________________________________ Process water flows from Cell 3 to the flash mixing/flocculation channel. Phosphorus is a nutrient that is removed using a chemical called liquid alum. Phosphorus exists in dissolved and particulate forms. Alum reacts with dissolved phosphorus to form a heavy sticky particle (floc). The flocs stick to other solids (including particulate phosphorus) and settle out.

Treatment Unit Processes: Alum Addition Removes phosphorus. Flash Mix / Floc Channel ________________________________________________________________ Alum Pumps Alum is pumped to the flash mixing/flocculation channel. The alum is rapidly mixed with the process water using flash mixers. The process water is gently mixed in the flocculation channel to form floc particles. After exiting the flocculation channel, the floc particles begin to settle.

Treatment Unit Processes: Chlorination Sterilizes the process water. Cell 2 Cell 1 Cell 3 Cell 4 Cell 5A Cell 5B Cell 6 Disinfection De-Chlorination Sodium Hypochlorite Metering Pumps Sodium Hypochlorite Storage Tanks and Containment Area ________________________________________________________________ Chlorine solution (sodium hypochlorite) is injected in the channel between Cells 4 and 5A. The chlorine concentration is monitored at the outlet of Cell 5A to ensure the concentration is high enough to disinfect the effluent.

Treatment Unit Processes: Dechlorination Removes excess chlorine from the effluent. Cell 2 Cell 1 Cell 3 Cell 4 Cell 5A Cell 5B Cell 6 Disinfection De-Chlorination Sodium Metabisulphite Storage Tanks & Metering Pumps ________________________________________________________________ Sodium metabisulphite solution is injected at the outlet of Cell 5B. The chlorine concentration is monitored at the outlet of Cell 5A to ensure there is no chlorine left in the effluent.

Effluent Quality: Summary Compliance testing is based on point by point data except in the case of Fecal Coliforms tested against the swimming standard limit of 200 CFU/100 mL which is based on the median of 7 samples.

River Water Quality: Summary

Environmental Impact of Lagoons Effluent Quality VERY GOOD (meets limits in 99% of samples; 3017 out of 3052 samples). River Water Quality No significant difference in WQ upstream to downstream of outfall (compliance w WQGs is 94.9% upstream, 95.7% downstream). Typically when downstream results DO NOT meet BC WQG limits it is because upstream results DO NOT meet the BC WQG limits. ________________________________________________________________

Glossary ________________________________________________________________

Thank You Q&A