1. Requirements to produce high quality water
Stephen Stanley, Ph.D., P.Eng.
EPCOR Water Services

2. Capable Plant Model High Quality Treated Water
Operation (process control)
Capable Plant
Administration
Design
Maintenance

3. Capable Plant
A capable plant means if it is managed, operated and maintained properly, the plant has the required infrastructure to meet all requirements
Criteria for capable plant largely dependent on regulation

4. Capable Plant
Requirements constantly changing as new information becomes available
turbidity requirements have gone from 5 NTU to 1 NTU to 0.5 NTU and now proposed to go to 0.3 NTU
Requirements for a capable plant also dependent on raw water source
ground water - disinfection
surface waters - filtration and disinfection

5. Capable Plant - Giardia Example

6. Capable Plant Multi-barrier Approach
Water treatment uses the concept of multi-barriers to meet treatment requirements
a number of treatment processes which are each barriers for contaminants
Giardia example for 4 log removal
Clarification 0.5 log removal
Filtration 2.0 log removal
Disinfection 1.5 log removal

7. Capable Plant - Cryptosporidium
One of the greatest challenges facing the water industry
Regulations just starting (US EPA and Canada)
Resistant to chlorine (loss of major barrier)
For conventional treatment must rely on particle removal
UV and ozone disinfection effective

8. Capable Plant - Regulation
Regulations generally based on the concept of reducing the risk associated with water to an “acceptable” level
other factors include available technology and economics
Poorer standards result in greater risk that public health can compromised
typically event related (when plant challenged)

9. Capable Plant - Summary
Requirements of a capable plant dependent on regulation
Also dependent on raw water source
Capability of plant restricted to design flow rates
A capable plant only provides the ability to produce high quality water if proper administration, maintenance and operational systems are in place

10. Adminstration
Relates to having administrative policies, and staffing and funding requirements needed to produce high quality water
Requires a commitment from senior administration to produce high quality water
Needs quality assurance and quality control programs to ensure high quality water
Must ensure adequate staffing and funding are available

11. Design
Design of a treatment facility must not only meet requirements for the capable plant but must also consider operational and maintenance realities
Design should also consider technical expertise required

12. Maintenance
To make a capable plant sustainable, regular maintenance must occur
Maintenance activities must consider operational constraints and must be planned accordingly
For critical systems redundancy may be required

13. Operations - Process Control
Water treatment of surface waters, especially those treating river waters is a very dynamic process
raw water quality may vary from a turbidity of 1 NTU to over 1000 NTU
water demand may vary by 3 times
Treatment plants must constantly vary operating conditions (chemical doses, flows, etc.)

14. Operations - Process Control
For process control require:
a measure of the state of the system
comparison of the current state to the desired state
an action (for example a change in chemical dose) to return the system to the desired state

15. Challenges in Process Control
Multiple and conflicting objectives
water quantity vs. water quality
disinfection vs. disinfection by-products
Multiple operating parameters
must simultaneously adjust more than one chemical dose and operating conditions

16. Challenges in Process Control
Long residence time in plant
if treated water turbidity increases and requires change in coagulant dose at front of plant, can have 3 to 5 hours of water in the plant that must pass through before change will be noticed
requires intermediate assessment of treatment process

17. Challenges in Process Control
No standard methods to determine proper chemical dosing
must rely heavily on operator experience
must ensure available tools are being used (jar tests)

18. Operations - Process Control
Upsets can occur in water treatment
Must have clearly defined emergency response plans
Should have programs such as a boiled water notice in place
Can not wait for illness

19. Production of High Quality Water
Requires not only a capable plant but proper administration, design, maintenance and operations
Failure in any of these areas significantly increases the risk to public health

20. The Challenge
Requirements for the production of high quality of water is largely independent of the size of the community
The complexity of the treatment system is largely dependent on the quality of the raw water
The challenge is implementing the requirements in smaller communities