a Municipal Perspective Environmental Utilities April 5, 2019 - - PowerPoint PPT Presentation

Water Protection from a Municipal Perspective

Environmental Utilities April 5, 2019

Water Protection from a Municipal Perspective Environmental Utilities City of Medicine Hat 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 Environmental Utilities City of Medicine Hat 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 Environmental Utilities City of Medicine Hat 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 Environmental Utilities City of Medicine Hat April 5, 2019

Backsiphonage

• Water main

breaks, flushing

• Booster pump

failure

• Emergency

firefighting water drawdown

Water Protection from a Municipal Perspective Environmental Utilities City of Medicine Hat April 5, 2019

Backpressure

• Pressure in

external system exceeds the pressure in the water distribution system

Water Protection from a Municipal Perspective Environmental Utilities City of Medicine Hat 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 Environmental Utilities City of Medicine Hat 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 Environmental Utilities City of Medicine Hat 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 Environmental Utilities City of Medicine Hat April 5, 2019

Source Control Program

Water Protection from a Municipal Perspective Environmental Utilities City of Medicine Hat 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 Environmental Utilities City of Medicine Hat April 5, 2019

Biological Treatment Facility

Water Protection from a Municipal Perspective Environmental Utilities City of Medicine Hat 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 Environmental Utilities City of Medicine Hat 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 Environmental Utilities City of Medicine Hat April 5, 2019

Prohibited Substances

• Any substance that can

adversely affect the

• peration 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 Environmental Utilities City of Medicine Hat April 5, 2019

Restricted Substances

• Health and safety – H2S
• Deterioration of the collection

system, treatment plant infrastructure and equipment

• High sulphates, chlorides →

Corrosion

• pH too low or too high →

Corrosion

• 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

Inorganic Contaminants

• Total metals, sulphates, chlorides

Organic Contaminants

• Hydrocarbons

Conventional Contaminants

• BOD, COD, TSS, FOG, TP, TKN, etc.

Physical/Chemical Properties

• pH, temperature

Water Protection from a Municipal Perspective Environmental Utilities City of Medicine Hat April 5, 2019

Monitoring, Education and Awareness

• Sampling program
• Site inspections
• Comprehensive wastewater characterization

Water Protection from a Municipal Perspective Environmental Utilities City of Medicine Hat April 5, 2019

Collection System Integrity and Operation

Water Protection from a Municipal Perspective Environmental Utilities City of Medicine Hat 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 Environmental Utilities City of Medicine Hat April 5, 2019

Q & A