Water Protection from a Municipal Perspective Environmental Utilities April 5, 2019
Overview • CMH Potable Water System • Cross Connection Control Program • Conditions that Cause Backflow • Methods of Backflow Prevention • Benefits of Backflow Prevention • Backflow Incident - Impact • CMH Wastewater System • Source Control Program • Sewer Bylaw and Discharge Permits – Prohibited, Restricted Substances • Monitoring, Education and Awareness • Benefits of Source Control Water Protection from a Municipal Perspective City of Medicine Hat Environmental Utilities April 5, 2019
CMH Potable Water System • City of Medicine Hat Water Treatment Plant services ~70,000 people • Distributed through ~430 KM of water mains • Draws raw water from South Saskatchewan River • Winter months ~25-30 million litres per day • Summer months ~75-125 million litres per day Water Protection from a Municipal Perspective City of Medicine Hat Environmental Utilities April 5, 2019
What is a Cross Connection? • A direct or potential connection between a potable water system and any source of pollution or contamination Water Protection from a Municipal Perspective City of Medicine Hat Environmental Utilities April 5, 2019
Backsiphonage • Water main breaks, flushing • Booster pump failure • Emergency firefighting water drawdown Water Protection from a Municipal Perspective City of Medicine Hat Environmental Utilities April 5, 2019
Backpressure • Pressure in external system exceeds the pressure in the water distribution system Water Protection from a Municipal Perspective City of Medicine Hat Environmental Utilities April 5, 2019
Methods of Backflow Prevention • Air gap • BFP assemblies • Annual BFP testing and maintenance • Certified BFP testers • BFP database Water Protection from a Municipal Perspective City of Medicine Hat Environmental Utilities April 5, 2019
Benefits of Backflow Prevention • Maintaining water quality - public health • Protection of the distribution system • Protection of the environment Water Protection from a Municipal Perspective City of Medicine Hat Environmental Utilities April 5, 2019
Backflow Incident - Impact • Stratford, Ontario – 2005 - 2-Butoxyethanol from concentrated carwash detergent • 2-Butoxyethanol: • Harmful if swallowed, inhaled • Eye, skin irritation • Combustible liquid • The entire city was affected, ~31,000 people • Several people required medical attention • Drinking water was affected for ~2 days https://www.cbc.ca/news/canada/stratford-eases-water-ban-after-car-wash-spill-1.564398 Water Protection from a Municipal Perspective City of Medicine Hat Environmental Utilities April 5, 2019
Source Control Program Water Protection from a Municipal Perspective City of Medicine Hat Environmental Utilities April 5, 2019
Wastewater System Overview • City of Medicine Hat Wastewater Treatment Plant services ~70,000 people including Redcliff • Collected through ~404 KM of wastewater mains • ~26 ML of wastewater are treated daily • Treated water discharged into South Saskatchewan River Water Protection from a Municipal Perspective City of Medicine Hat Environmental Utilities April 5, 2019
Biological Treatment Facility Water Protection from a Municipal Perspective City of Medicine Hat Environmental Utilities April 5, 2019
Source Control • Wastewater system is a high value, essential capital asset with fixed and finite capabilities • Upstream management of contaminants is important for managing: • Health and safety of wastewater employees and the public • Wastewater system integrity • Wastewater treatment plant (WWTP) performance • Environmental protection Water Protection from a Municipal Perspective City of Medicine Hat Environmental Utilities April 5, 2019
Sewer Bylaw and Discharge Permits • Regulates the use of the wastewater system • Lists prohibited wastes that can not be discharged • Limits the amount of restricted substances that can be discharged • Determined by system capacity, treatment capabilities and effects on the system Water Protection from a Municipal Perspective City of Medicine Hat Environmental Utilities April 5, 2019
Prohibited Substances • Any substance that can adversely affect the operation of the wastewater system • Anything that can cause regulatory non-compliance • Anything that can restrict the beneficial use of biosolids • Examples: explosive, radioactive, biomedical and non-biodegradable substances Water Protection from a Municipal Perspective City of Medicine Hat Environmental Utilities April 5, 2019
Restricted Substances Inorganic Contaminants • Health and safety – H 2 S • Total metals, sulphates, chlorides • Deterioration of the collection Organic Contaminants system, treatment plant • Hydrocarbons infrastructure and equipment Conventional Contaminants • High sulphates, chlorides → • BOD, COD, TSS, FOG, TP, TKN, etc. Corrosion • pH too low or too high → Physical/Chemical Properties • Corrosion pH, temperature • Cost of replacing, repairing, and/or rehabilitating these assets can be substantial • Reduced biological wastewater treatment effectiveness • Potential contravention of the City’s WWTP approval requirements Water Protection from a Municipal Perspective City of Medicine Hat Environmental Utilities April 5, 2019
Monitoring, Education and Awareness • Sampling program • Site inspections • Comprehensive wastewater characterization Water Protection from a Municipal Perspective City of Medicine Hat Environmental Utilities April 5, 2019
Collection System Integrity and Operation Water Protection from a Municipal Perspective City of Medicine Hat Environmental Utilities April 5, 2019
Benefits of Source Control Program? • Health and safety - City employees and the public • Environmental protection • Integrity of wastewater infrastructure and equipment • Quality of biosolids Water Protection from a Municipal Perspective City of Medicine Hat Environmental Utilities April 5, 2019
Q & A Water Protection from a Municipal Perspective City of Medicine Hat Environmental Utilities April 5, 2019
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