City of Sault Ste. Marie Drinking Water System - Taste & Odour Concerns Update After Conversion to Free Chlorine

Transcription

1 City of Sault Ste. Marie Drinking Water System - Taste & Odour Concerns Update After Conversion to Free Chlorine Council Meeting May 14, 2012

2 Presentation Outline 1. Drinking Water Disinfection Background Information 2. History of Water Disinfection in Sault Ste. Marie 3. Walkerton and Changes to Regulations 4. Kresin Engineering Sentinel Monitoring Program 5. Stantec Inc. Chlorination Feasibility Study 6. Benefits of Free Chlorine Use 7. History of Taste & Odour Concerns in Sault Ste. Marie 8. Potential Impacts Reverting to Chloramine 9. PUC Action Plan to Address Customer Concerns 10. Closing Review (Public Notice Items after discussions conclude) May 14,

3 Drinking Water Quality Concerns Two Issues: Health versus Aesthetics SSM s drinking water is absolutely safe for consumption! Vast majority of health related parameters are well below prescribed ODWS limits (exceptions include lead and sodium) Most parameters tested show non-detect levels or levels 10 times below the MAC (Maximum Acceptable Concentration) Bacteria: E-coli, total Coliforms and HPC (Table 1) 78 chemical parameters (Table 2) radionuclides (Table 3) All analyses performed by independent, provincially certified laboratories PUC operations audited by MOE inspectors twice annually Water Quality Annual Reports available to the public Posted on PUC website since 2003 at May 14,

4 Water Quality Reports for Sault Ste. Marie May 14,

5 Disinfection of Drinking Water Background Information Ontario regulations require presence of a persistent disinfectant in the distribution system to ensure safe water (i.e. chlorine residual) Only two approved methods for providing persistent residual Chlorine or Chloramine Chlorine alone (free chlorine) Combine chlorine with ammonia to form Chloramine (combined chlorine) Free Chlorine is the first choice and the most widely used method around the world May 14,

6 Disinfection of Drinking Water Free Chlorine Use in Ontario Currently 693 regulated drinking water systems in Ontario Only 14 use Chloramine (In USA, 79% of the population served with Free Chlorine) May 14,

7 Sault Ste. Marie Water Supply Some History Chlorine used in SSM s drinking water for at least 100 years Water quality became an issue again during the summer of 1912 when an outbreak of typhoid in the city was traced back to the failure of the Tagona Water and Light's chlorine plant. ( History of PUC - PUC website) Chlorine gas used for at least past 50 years Still use the same chlorine gas today Ammonia used since at least mid 1950 s May 14,

8 Sault Ste. Marie Water Supply Historical Timeline of Disinfection May 14,

9 Sault Ste. Marie Water Supply More History Pre surface water intake located at foot of Huron Street in shipping canal -- wells in west end and east end Both surface water and ground water contained measurable phenols prior to mid 1970 s (industrial discharges) Chlorine mixing with phenols creates objectionable taste and odour compounds in the treated water (chlorophenols) Chlorophenolic taste different from bleachy/chlorinous taste Ammonia was injected before chlorine to bind the chlorine and prevent formation of chlorophenols May 14,

10 Sault Ste. Marie Water Supply A Little More History Since 1985 surface water intake now at Gros Cap Phenols no longer an issue for surface water Phenols in ground water no longer being detected Chlorophenols have been non-detect past 10+ years at least Chloramine no longer necessary Ammonia no longer required May 14,

11 Walkerton 2000 Government Response Significant regulatory changes following Walkerton report Every system in Ontario had to increase chlorine residual levels Residuals at ~ 0.7 mg/l prior to 2001 Residuals at ~ 1.5 mg/l prior to free chlorine switch PUC also had to raise disinfection levels at the wells to meet MOE requirements One option: increase length of contact mains not feasible Alternative: switch ammonia injection to after chlorine injection 2008 started well disinfection upgrades - completed June 2009 Pipes rearranged to inject Ammonia after the Chlorine May 14,

12 Sentinel Monitoring Program After Well Disinfection Upgrades Kresin Engineering Presentation Overview of Sentinel Monitoring Program & Potential Causes or Contributors to T&O May 14,

13 Why Switch to Free Chlorine? After well upgrades, scale buildup in ammonia injection pipes created ongoing operational problems Require costly de-scaling every 2 to 3 months (~ $360,000 per year) Water softening equipment required to minimize scaling Costs estimated at Capital $810,000 + Annual O&M $30,000 Corrosion Control required under new lead regulations To control lead in drinking water from service pipes and fixtures Costs estimated at Capital $1,260,000 + Annual O&M ~ $55,000 Potential total additional costs: Capital ~ $2 million + Annual O&M ~ $85,000 Switch to free chlorine to avoid added costs and chemicals May 14,

14 Planning & Implementation Switch to Free Chlorine Stantec commissioned to carry out feasibility study Additional sampling conducted to confirm feasibility Planning for conversion approximately ~ 10 months PUC involved Algoma Public Health, local MOE office, and Toronto MOE office throughout the process How was switch to free chlorine achieved? turned off the ammonia May 14,

15 Planning & Implementation Switch to Free Chlorine Stantec Presentation Overview of Feasibility Study May 14,

16 Benefits of Using Free Chlorine 1. Eliminate addition of ammonia to city s drinking water Used to inject ~ 18 Tonnes of ammonia per year into drinking water Benefit to staff - eliminate handling of hazardous chemical 2. Use 30% less chlorine (compared to using chloramine) 3. Avoid ~ $2 million capital & $85,000 per year operating costs Avoid cost of softening equipment and long term operating costs (i.e. avoid addition of sodium chloride) Expected to reduce lead in water -- avoid corrosion control (i.e. avoid addition of another chemical to control water corrosivity) 4. Better maintenance of chlorine residual throughout the distribution system safer water for consumers May 14,

17 More Benefits of Using Free Chlorine 5. Expected to correct historical periodic taste and odour related problems due to nitrification in the distribution pipes associated with the use of chloramine 6. Reduces SSM s carbon footprint Due to avoided production for both Ammonia and Chlorine No more ammonia & 30% less chlorine used Saves approx. 31 GWh of electricity per year (power 2,500 homes) Eliminates 5.3 Tonnes of green house gases per year May 14,

18 History of Taste & Odour Complaints Always had taste & odour (T&O) complaints in Sault Ste. Marie January 2000 to May complaints related to T&O only June 2009 to October 27, 2011 (following CT upgrades & prior to conversion to free chlorine) Complaints During chlorine conversion October 28 to December 31, complaints (includes repeat calls from same address) Since January 1, 2012 (including repeat calls): Up to Council Meeting April 2-94 complaints (7 /week) After Council Meeting April 2 up to April complaints (27 /week) After Council Meeting April 16 up to May complaints (47 /week) Approx. 25,000 homes and businesses are on city water May 14,

19 Taste & Odour Concerns - GIS locations January 1, 2000 to May 31, 2009 Total 141 Calls May 14,

20 Taste & Odour Concerns - GIS locations June 1, 2009 to October 27, 2011 Total 163 Calls May 14,

21 Taste & Odour Concerns - GIS locations October 28 to December 31, 2011 Total 386 Calls May 14,

22 Taste & Odour Concerns - GIS locations January 1 to April 2, 2012 Total 94 Calls May 14,

23 Taste & Odour Concerns - GIS locations April 3 to April 16, 2012 Total 55 Calls May 14,

24 Taste & Odour Concerns - GIS locations April 17 to May 10, 2012 Total 109 Calls May 14,

25 Where do we go from here? Provincial regulations have changed PUC must comply The regulations dictate level of disinfection required at wells and in the distribution system PUC can only choose the method PUC s objective: to provide safe, acceptable drinking water by the most cost effective method possible Free Chlorine is the first choice, world wide Free Chlorine is currently providing safer drinking water for all PUC customers than previous chloramine May 14,

26 Potential Consequences of Reverting to Chloramine Two options available for return to chloramine: 1. Revert to post well upgrades method (June 2009 to October 2011) Inject chlorine first followed by ammonia 2. Revert to pre well upgrades method (prior to June 2009) Inject ammonia first followed by chlorine May 14,

27 Impacts of Reverting to Chloramine Option 1 Option 1. (post well upgrades method) 1. Must add softening chemicals for ammonia injection lines 2. Must add corrosion control chemicals to entire system 3. Will cost $2 million in capital works over 4 to 5 years 4. Will add approx. $85,000 per year of operating costs 5. Will not correct all taste & odour problems (as evidenced by the T&O complaints in ) May 14,

28 Impacts of Reverting to Chloramine Option 2 Option 2. (pre 2009 well upgrades method) 1. Must relocate ammonia injection to ahead of chlorine injection 2. Must add corrosion control chemicals to entire system 3. Must add additional method of disinfection to achieve CT rule Ozone or UV are the only viable options Ozone will create additional Disinfection By-Products (DBPs) and may have to be augmented with hydrogen peroxide UV will require significant capital costs and is likely the only option UV will add substantial operating costs for power requirements Estimated capital costs of $3.7 million (wells only) Estimated O&M costs of approx. $80,000 per year 4. No guarantee that T&O concerns will be corrected May 14,

29 First Objective: PUC Action Plan to Address Customer Concerns To differentiate between T&O from chlorine versus T&O from disinfection by-products (such as chlorophenols) Action #1 - Undertake Augmented Sampling Program PUC already sampling beyond regulatory requirements PUC will extend scope of sampling even further (i.e. additional parameters have been identified for ongoing sampling) PUC will use enhanced laboratory methods to increase detection levels 10x greater than past analysis methods PUC will perform augmented residential premise sampling May 14,

30 PUC Action Plan to Address Customer Concerns Second Objective: To enhance cleaning out of distribution pipes Action #2 Institute Uni-Directional Flushing Aging infrastructure Buildup of internal corrosion scales and sediment Requires more aggressive flushing beyond past practice PUC will implement Uni-Directional Flushing Temporary, localized discoloured water will result Activity necessary to improve water quality (including T&O) May 14,

31 PUC Action Plan to Address Customer Concerns Third Objective: To get an accurate understanding of customer satisfaction Action #3 - PUC will conduct independent, third party survey Must be statistically accurate and random across whole city Will be done fourth quarter 2012 PUC will update action plan following analysis of survey results All results will be published in media and PUC website and presented at open Council Meeting May 14,

32 Summary review and Conclusion May 14,

33 SSM Disinfection Process Prior to June 2009 Ammonia (NH 3 ) Chlorine (Cl 2 ) prior to mid 1990 s - chlorine residual ~ 0.3 ppm Regulation Change Walkerton O. Reg. 459/00 Increase chlorine Ammonia (NH 3 ) Chlorine (Cl 2 ) after Walkerton - chlorine residual ~ 1.5 ppm May 14,

34 SSM Disinfection Process Prior to October 27, 2011 Ammonia (NH 3 ) Chlorine (Cl 2 ) Prior to Well Upgrades June 2009 Regulation Change O. Reg. 170/03 CT value required Advantages Controls T&O in presence of phenols Persistent residual in the distribution system Chlorine (Cl 2 ) Disadvantages Weak disinfection strength Supports nitrification -- periodic T&O episodes Unable to meet regulatory CT requirement Promotes lead leaching from service lines and household fixtures Ammonia (NH 3 ) After Well Upgrades June 2009 Advantages Satisfies regulatory CT requirement Persistent residual in the distribution system Disadvantages Potential for T&O in presence of phenols or due to nitrification Promotes lead leaching from service lines and household fixtures May 14,

35 Disinfection Options Choices at December 2010 Option #1 Chlorine (Cl 2 ) Since Chlorine Conversion October 27, 2011 Regulation Change O. Reg. 170/03 Lead Action Plan Advantages Disadvantages Most effective disinfection possible Potential T&O if trace phenols exist Satisfies regulated CT requirements Increased potential for detectable Should minimizes lead in water at the tap chlorine T&O Eliminates addition of ammonia Prevents periodic T&O episodes (nitrification) Chlorine (Cl 2 ) Ammonia (NH 3 ) Option #2 Softening (NaCl) Advantages Persistent disinfection residual in distribution system Corrosion Control (Polyphosphate or Soda Ash) Disadvantages Less effective disinfection in distribution system Continued T&O problems as experienced through 2010 Scaling of ammonia lines requiring softening chemicals Leaching of lead requiring corrosion control chemicals May 14,

36 Closing Comments PUC has had to make changes to satisfy provincial regulations PUC has taken action to provide safe drinking water in the most cost effective manner possible System monitoring data shows we have a safer system today PUC recognizes there are taste and odour concerns PUC is doing everything possible to optimize the system to address T&O concerns But provincial regulations dictate we cannot go back to the way it was May 14,

37 Questions? May 14,