Dealing with Unexpected Wastewater Treatment Plant Disruptions. February 16, 2017

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1 Dealing with Unexpected Wastewater Treatment Plant Disruptions February 16, 2017

2 Location Map

3 WPCP History Original WPCP constructed on this site in 1928 consisting of primary treatment and chlorination; In 1958, pre-treatment of sewage began, with the installation of a bar screen and grit removal; Major expansion in 1967: secondary treatment established with the addition of aeration tanks an a secondary clarifier; Construction of the Orangeville Reservoir (now called Island Lake) began in 1968 and was completed in 1970 in order to provide flow augmentation during drought periods to ensure sufficient dilution of WPCP effluent; Major expansion in 1975: tertiary treatment established with the installation of a sand filter; Major expansion in 1985: addition of de-nitrification tanks, changing the process to pre-de-nitrification. Major expansion : increase plant capacity and significantly improve the monitoring and control capabilities.

4 WPCP Treatment Process Old Plant Grit Removal Denitrification Aeration Secondary Clarification Influent Screening/ Raw Sewage Pumping Filtration Raw Sewage Sludge Thickening/ Anaerobic Digestion/ Sludge Storage Flow Splitting Chamber New Plant Grit Removal Denitrification Aeration Secondary Clarification Disinfection Dechlorination Credit River Outfall

5 Orangeville Water Pollution Control Plant New Plant Chlorination Old Plant Screening & Pumping Tertiary Filtration Biosolids Digestion & Storage

6 Planning for Abnormal Operating Events Standard Operating Procedures (SOPs) Bypass Events Taking Process Equipment Out of Service Process Disturbances

7 Primary Bypass Rarely occurs Raw sewage flows exceed raw sewage pump capacity Entire treatment process is bypassed for a portion of the raw sewage Raw sewage bypassing the treatment plant is chlorinated and dechlorinated Planning for Abnormal Operating Events: Bypass

8 WPCP Treatment Process Grit Removal Denitrification Aeration Secondary Clarification Disinfection Dechlorination Influent Screening/ Raw Sewage Pumping Sludge Thickening/ Anaerobic Digestion/ Sludge Storage Flow Splitting Chamber Filtration Raw Sewage Dechlorination Credit River Outfall Grit Removal Denitrification Aeration Secondary Clarification Disinfection

9 Planning for Abnormal Operating Events: Bypass Partial Tertiary Bypass Occasionally occurs A portion of the wastewater flows bypasses filtration Preliminary treatment, primary/secondary treatment, chlorination and dechlorination still occurs

10 WPCP Treatment Process Grit Removal Denitrification Aeration Secondary Clarification Influent Screening/ Raw Sewage Pumping Filtration Raw Sewage Sludge Thickening/ Anaerobic Digestion/ Sludge Storage Flow Splitting Chamber Grit Removal Denitrification Aeration Secondary Clarification Disinfection Dechlorination Credit River Outfall

11 Planning for Abnormal Operating Events: Bypass Following the implementation of emergency bypass procedures, WPCP Operators are required to notify: Operations Centre Manager Spills Action Centre Credit Valley Conservation Medical Officer of Health SAC Town Hall WPCP CVC MOH

12 Planning for Abnormal Operating Events: Process Equipment Out of Service Usually a planned event SOPs for Clarifiers SOPs for Denitrification/Aeration Tanks Informal agreement with CVC for advance notification of planned shutdown; MOECC copied on notification

13 Planning for Abnormal Operating Events: Process Disturbances Bulking sludge Hydraulic overload Digester Foaming High solids build up in filters Toxic influent Clarifier rake arm high torque Chemical spill Accidental chemical mixing Sludge spill at loading area Power failure Clogged air lift in air grit classifier

14 Case Study Spring 2001 Background OCWA operated the WPCP on behalf of the Town from 1993 through 2011 Extra biosolids storage was required in winter/spring 2000/2001 Early snowfall in Fall 2000 restricted end-ofseason land application Few fields to spread biosolids in early spring Additional offsite storage was still insufficient

15 Case Study Spring 2001 A New Plant aeration cell converted into temporary storage for sludge Prevented solids from being discharged to Credit River BUT Remaining treatment capacity overextended Digesters/sludge storage tank overflowed Excessive odour from remaining aeration cells (biological process upset)

16 Solution Case Study Spring 2001 Partially treated solids removed off-site for final treatment Digester could not handle increased solids Arrangements made with Shelburne and Fergus Additional blower brought online to improve nitrification and allow biological process to recover

17 Case Study Spring 2001 Raw sewage samples indicated organics concentrations higher than the design capacity of the WPCP Investigate to determine source of high BOD loading Improve their manufacturing processes to reduce BOD in wastewater Enter into an overstrength agreement

18 Case Study Spring 2001 Going Forward Improved communication between OCWA and Town Staff Increased sampling and testing frequency at the WPCP Maintain a reliable source for additional blower(s) in the event they are required in the future Consider alternatives to land spreading, such as a dewatering facility and/or portable dewatering equipment Establish a contingency plan to deal with such emergencies

19 Background Case Study Spring/Summer 2016 Late April 2016: contractor accidently knocked concrete blocks into one of the New Plant Clarifiers. Procedure to take clarifier off line was implemented Early May 2016: Clarifier brought back on-line; sample results revealed high ammonia levels in the New Plant

20 Clarifier at WPCP

21 Case Study Spring/Summer 2016 Solution: 1. Run all New Plant blowers simultaneously; 2. Seed the New Plant with solids from the Old Plant; and 3. Daily sampling for ammonia and DO in all five aeration tanks. After peaking in mid-may, ammonia levels declined, but still high WPCP was out of compliance with the Environmental Compliance Approval for Ammonia for the month of May The MOECC were informed that the WPCP was out of compliance

22 Case Study Spring/Summer 2016 Elevated levels of ammonia, nitrogen and CBOD detected in May 25th samples from Credit River This information was immediately shared with CVC and MOECC staff Frequency of Credit River monitoring for 2016 increased to twice monthly

23 Case Study Spring/Summer 2016 Early June WPCP effluent results showed an increase in ammonia levels Outside treatment process consultants were contacted for their assistance Mid-June ammonia levels within compliance limits. Ammonia levels spiked again at the end of June, hovered around the compliance limit for much of July, and spiked again in late July and continued to remain high through mid-august

24 Case Study Spring/Summer 2016 Additional consultation with experts recommended increasing aeration capacity August 10th: new blower brought on-line August 11th: ammonia levels dropped well below the compliance limit Ammonia levels have remained at these levels since that time CVC and MOECC staff were provided with weekly updates throughout this event

25 Case Study Spring/Summer 2016 Going Forward Standard Operating Procedure for taking a Clarifier off-line to be revised to include the need to remove the solids from the bottom of the tank immediately Expanded WPCP will include significantly more aeration capacity and new aeration piping WPCP expansion includes significant improvements to our monitoring and control capabilities

26 Thank you!!