SOURCE WATER PROTECTION DRINKING WATER SYSTEMS ISSUES EVALUATION OXFORD COUNTY PUBLIC WORKS DEPARTMENT OCTOBER 2009
TABLE OF CONTENTS 1. INTRODUCTION...1 1.1. CLEAN WATER ACT AND THE ISSUES IDENTIFICATION/EVALUATION PROCESS...1 1.2. OXFORD COUNTY WATER SUPPLY SYSTEMS...1 2. METHODOLOGY...3 2.1. ISSUE SCREENING...3 2.2. DATA SOURCE...3 2.3. MONITORING WELLS...3 2.4. PATHOGENIC ISSUES...3 2.5. FLUORIDE AND SODIUM...3 2.6. ISSUE IDENTIFICATION...4 2.7. WELL GROUPINGS...4 3. ISSUES SCREENING SYSTEM SPECIFIC...5 3.1. BEACHVILLE WATER SUPPLY SYSTEM...5 3.2. BRIGHT WATER SUPPLY SYSTEM...5 3.3. BROWNSVILLE WATER SUPPLY SYSTEM...6 3.4. DEREHAM CENTRE WATER SUPPLY SYSTEM...7 3.5. DRUMBO WATER SUPPLY SYSTEM...8 3.6. EMBRO WATER SUPPLY SYSTEM...8 3.7. HICKSON WATER SUPPLY SYSTEM...9 3.8. INGERSOLL WATER SUPPLY SYSTEM...10 3.9. INNERKIP WATER SUPPLY SYSTEM...11 3.10. LAKESIDE WATER SUPPLY SYSTEM...12 3.11. MOUNT ELGIN WATER SUPPLY SYSTEM...13 3.12. NORWICH WATER SUPPLY SYSTEM...14 3.13. OTTERVILLE-SPRINGFORD WATER SUPPLY SYSTEM...15 3.14. PLATTSVILLE WATER SUPPLY SYSTEM...16 3.15. TAVISTOCK WATER SUPPLY SYSTEM...17 3.16. THAMESFORD WATER SUPPLY SYSTEM...18 3.17. TILLSONBURG WATER SUPPLY SYSTEM...19 3.18. WOODSTOCK WATER SUPPLY SYSTEM...21 3.19. SUMMARY OF SCREENED POTENTIAL ISSUES...22 4. ISSUE EVALUATION PARAMETER SPECIFIC...23 4.1. FLUORIDE...23 4.2. ARSENIC...23 4.3. TRIHALOMETHANES...23 4.4. NITRATE...23 4.5. BACTERIOLOGICAL PARAMETERS...24 4.6. TRICHLOROETHYLENE AND TETRACHLOROETHYLENE...24 4.7. HARDNESS...24 4.8. SODIUM...24 4.9. IRON AND MANGANESE...24 4.10. TDS, COLOUR AND SULPHATES...25 4.11. HYDROGEN SULPHIDE...25 4.12. ORGANIC NITROGEN...25 4.13. SUMMARY OF ISSUE IDENTIFICATION...25 APPENDIX A: TECHNICAL RULES 114-116 APPENDIX B: TSR ISSUES EVALUATION METHOLOGY APPENDIX C: WATER QUALITY ANALYTICAL DATA
1. INTRODUCTION 1.1. CLEAN WATER ACT AND THE ISSUES IDENTIFICATION/EVALUATION PROCESS The Clean Water Act was enacted in 2006 to assist with the protection of Ontario s drinking water sources. The intent of the Act is to develop Source Protection Plans to identify and manage the risks to municipal drinking water. The first step in developing the Plans is completing an Assessment Report which will compile the technical information necessary to implementing the Plans. In December 2008 the Province issued Technical Rules to guide the development of components of the Assessment Report. The Technical Rules provide the legal requirements of the components. This report is intended to fulfill Technical Rules 114, 115 and 116 which relate to the identification of water quality issues in a drinking water source. Rules 114, 115 and 116 are provided in full in Appendix A however in summary the rules require the water quality of municipal drinking water sources and associated monitoring wells be assessed. Rule 114 mandates that the Ontario Drinking Water Quality Standards (ODWS) and the Objectives and Guidelines associated with the Standards be used as the benchmark against which the water quality is compared. Rules 115 and 116 specify the information to be included when an issue is identified. In addition to the Technical Rules, the Thames Sydenham and Region Source Protection Region (TSR) has produced a methodology to guide the identification and description of drinking water quality issues. The methodology is provided in Appendix B. 1.2. OXFORD COUNTY WATER SUPPLY SYSTEMS Oxford County is located in Southwestern Ontario and is comprised of eight (8) area municipalities: the City of Woodstock, the Towns of Ingersoll and Tillsonburg and the Townships of Blandford Blenheim, East Zorra-Tavistock, Norwich, South West Oxford and Zorra (Figure 1). As shown on Figure 2 the lands within the County fall into four (4) different Conservation Authorities: Catfish Creek, Grand River, Long Point Region, and Upper Thames River. The County has responsibility for the provision of municipal drinking water and owns nineteen (19) separate systems as shown on Figure 1. The County is entirely dependant upon groundwater for its drinking water source and operates 57 production wells with another four wells in the planning stage. A summary of each system is provided in Section 3 of this report. Page 1
Figure 1: Oxford County Water Systems Figure 2: Conservation Authorities Page 2
2. METHODOLOGY This report is meets the requirements of Technical Rules 114, 115 and 116 and is consistent with the TSR Issues Evaluation methodology. Specifics regarding Oxford s approach to the identification of issues are provided below. 2.1. ISSUE SCREENING Parameters have been screened for closer investigation where any of the following criteria have been met: Consistent presence of microbiological parameters The parameter has a health related Maximum Acceptable Concentration (MAC) associated with it and the concentration in the raw or treated water exceeds half of the MAC level (with the exception of fluoride: see section 2.5) The parameter does not have a health related MAC but the concentration observed exceeds the objective or guideline associated with the ODWS (see section 2.5 for Sodium) 2.2. DATA SOURCE The water quality data used in this evaluation was compiled by the Oxford County Public Works Department. The data comprises the analytical results taken as part of operating the systems in addition to water quality results received as part of other programs/projects. Ministry sources referenced in the TSR methodology were not utilized as all those sources obtained their information from the County data. The bulk of the data used in this evaluation is from 2001 to present. Older data has been used where relevant. 2.3. MONITORING WELLS In general, Oxford County does not maintain a water quality monitoring program at monitoring wells. Monitoring wells have typically been used to assess water quantity impacts on the municipal aquifer (i.e. depth to water table). The primary exception to this is the Woodstock Water System s Thornton Well Field. Outside of this wellfield, no water quality data from monitoring wells is available for the purpose of this report. 2.4. PATHOGENIC ISSUES Oxford County has not completed any testing for pathogenic organisms at any of the well supplies as part of this report. Engineer s Reports were completed for all County systems in 2000/2001 in accordance with Ontario Regulation 459/00. The reports included an assessment of the wells with respect to the potential to be Groundwater Under the Direct Influence of surface water (GUDI). The majority of the supplies were found to be secure groundwater and the few wells that are GUDI have effective in-situ filtration and have no indicators of microbial contamination. Therefore no pathogenic issues have been included in this report. 2.5. FLUORIDE AND SODIUM Fluoride has a MAC of 1.5 mg/l however the ODWS states that where naturally occurring fluoride is present at levels between 1.5 mg/l and 2.4 mg/l and the operating authority does not fluoridate that the 1.5 mg/l level is a reporting requirement and treatment is not required where the concentration is below 2.4 mg/l. In Oxford County, several of the municipal bedrock wells have elevated levels of naturally occurring fluoride. As Oxford does not add fluoride at any system, the screening threshold for this parameter has been set at half of the treatment level of 2.4 mg/l. Page 3
Sodium has an aesthetic objective of 200 mg/l at which level the water will have a discernable salty taste. A reporting limit of 20 mg/l has been set in order to provide information to individuals with sodium restricted diets. For the purpose of this report, sources with sodium above 20 mg/l will be mentioned however the screening threshold of 200 mg/l will be utilized. 2.6. ISSUE IDENTIFICATION Parameters meeting the screening threshold were further reviewed to determine whether to identify them as issues. The considerations included: Whether the concentration is at or trending towards a health related MAC The frequency with which the parameter meets the screening threshold Capabilities of the treatment facility The ability of the parameter to interfere with/upset the treatment process Whether the parameter is related to concerns/issues raised by the public Importance of the well to the overall supply 2.7. WELL GROUPINGS Where wells are located in close proximity and have similar water quality characteristics, they have been grouped together into wellfields. This was done in an attempt to reduce the repetitiveness of the report and to be consistent with how the Operating Authority considers and responds to water quality issues. Page 4
3. ISSUES SCREENING SYSTEM SPECIFIC In the following section a brief description of each County drinking water system is provided followed by a screening of the parameters associated with the system s sources and a summary of the potential issues. Detailed analytical results for each system can be found in Appendix C. 3.1. BEACHVILLE WATER SUPPLY SYSTEM 3.1.1. Background The Beachville Drinking Water System provides water from one 91 m deep well that is secure groundwater. It is a Small Municipal Water system as defined by Regulation 170/03 and serves a portion of the larger Village of Beachville. The system has a population of approximately 130 and Village residents not connected to the municipal system obtain drinking water from individual private wells. The only water treatment is disinfection with sodium hypochlorite. 3.1.2. Water Quality Both raw and treated chemistry results were reviewed since the treatment does not substantially alter the water quality. No parameters were found to exceed their Maximum Acceptable Concentration (MAC). The fluoride concentration of the water marginally exceeds half of the reporting MAC value of 1.5 mg/l at a value of 0.76 mg/l. As mentioned in section 2.5, given that the fluoride is naturally occurring in the local bedrock, the treatment limit of 2.4 mg/l is being used for as a screening value. Microbiological results are consistently good and indicate no concerns. With the exception of Hardness, no operational or aesthetic parameters exceed the associated objectives or guidelines. Hardness which has an operational guideline (OG) range from 80 to 100 mg/l is typically exceeded in groundwater systems. The Beachville hardness concentration is around 300 mg/l. This parameter is naturally occurring in the Beachville groundwater and does not a health risk nor does it impact the treatment process. 3.1.3. Screening Result and Discussion The only parameter in the Beachville Water Supply System to meet the screening threshold is Hardness. The hardness is a naturally occurring parameter typical to most groundwater sources and does not affect treatment. 3.2. BRIGHT WATER SUPPLY SYSTEM 3.2.1. Background The Bright Drinking Water System provides water from two wells, 27m and 38m deep, that are secure groundwater. Disinfection using sodium hypochlorite and addition of sodium silicate to sequester iron are the only forms of treatment. It is a Large Municipal Water system as defined by Regulation 170/03 and serves a population of approximately 405. 3.2.2. Water Quality substantially alter the water quality. No parameters were found to exceed their Maximum Acceptable Concentration (MAC). Microbiological results are consistently good and indicate no concerns. Page 5
The system has several operational or aesthetic parameters exceed the associated objectives or guidelines as detailed below. Hardness which has a guideline range from 80 to 100 mg/l is typically exceeded in groundwater systems. The Bright hardness concentration is typically around 300 to 400 mg/l. This parameter is naturally occurring in the groundwater and does not a health risk nor does it impact the treatment process. The Sodium concentration ranges from 39 to 52 mg/l which is above the reporting level of 20 mg/l but well below the objective of 200 mg/l. Chloride levels in the system are quite low suggesting that the sodium is not caused by road salt application but rather is naturally occurring. No increasing trend is evident in the results. Total Dissolved Solids (TDS) levels in the Bright system exceed the objective of 500 mg/l and are around 600 mg/l. TDS is an aesthetic parameter and does not impact health or the treatment process. No increasing trend is evident in the results. The raw water in the system exceeds the objective of 0.3 mg/l for Iron. The raw water is around 0.5 mg/l. Iron is an aesthetic parameter and does not interfere with the treatment process. No increasing trend is evident. 3.2.3. Screening Result and Discussion The parameters in the Bright Water Supply System that meet the screening threshold are Hardness, TDS and Iron. These parameters are all naturally occurring and typical to groundwater sources. They do not affect the treatment process and there is no evidence of upward trending. 3.3. BROWNSVILLE WATER SUPPLY SYSTEM 3.3.1. Background The Brownsville Drinking Water System provides water from two wells, 32m and 47m deep, that are secure groundwater. Disinfection using sodium hypochlorite is the only form of treatment. It is a Large Municipal Water system as defined by Regulation 170/03 serving a population of approximately 490. 3.3.2. Water Quality substantially alter the water quality. No parameters were found to exceed their MAC. Microbiological results are consistently good and indicate no concerns. The Fluoride concentration ranges from 1.7 to 1.9 mg/l which is above half of the MAC of 2.4 mg/l. The fluoride is naturally occurring in the groundwater and does not appear to be trending upwards. Its presence does not impact the treatment process. Trihalomethanes (THMs) are a group of chemicals that are known to be carcinogenic and have a MAC of 100 mg/l. Typically THMs are found in treated drinking water due to a reaction between the chlorine used for disinfection purposes and organic material in the raw water. The THMs in the Brownsville system are above the half MAC value and range from 57 to 65 mg/l. The levels are stable and not trending upwards. The system has several operational or aesthetic parameters exceed the associated objectives or guidelines as detailed below. Page 6
Hardness has a guideline range from 80 to 100 mg/l. The Brownsville hardness concentration is slightly below the range at 70 to 75 mg/l. This parameter is naturally occurring in the groundwater and does not a health risk nor does it impact the treatment process. The Sodium concentration ranges from 79 to 85 mg/l which is above the reporting level of 20 mg/l but well below the objective of 200 mg/l. Chloride levels in the system are quite low suggesting that the sodium is not caused by road salt application but rather is naturally occurring. No increasing trend is evident in the results. The aesthetic objective for colour is 5 True Colour Units (TCU). The system has a value of 6 which marginally above the objective. There is insufficient information to determine whether the value is trending upwards, however the parameter does not impact the treatment process. 3.3.3. Screening Result and Discussion The parameters in the Brownsville Water Supply System that meet the screening threshold are Fluoride, THMs, Hardness, and Colour. These parameters are all naturally occurring and typical to groundwater sources. They do not affect the treatment process and there is no evidence of upward trending. 3.4. DEREHAM CENTRE WATER SUPPLY SYSTEM 3.4.1. Background The Dereham Centre Drinking Water System provides water from one 36m deep well that is secure groundwater. Disinfection using sodium hypochlorite and the addition of sodium silicate to sequester iron are the only forms of treatment. It is a Small Municipal Water system as defined by Regulation 170/03 and serves a population of approximately 47. 3.4.2. Water Quality substantially alter the water quality. No parameters were found to exceed their MAC. Microbiological results are consistently good and indicate no concerns. The arsenic levels in Dereham Centre are right around half of the MAC of 0.025 mg/l. Arsenic is naturally occurring in the raw water and does not appear to be trending upwards. It is anticipated however, that the province will lower the MAC to 0.010 mg/l in the near future. With the exception of Hardness, Iron and Organic Nitrogen no operational or aesthetic parameters exceed the associated objectives or guidelines. Hardness which has a guideline range from 80 to 100 mg/l is typically exceeded in groundwater systems. The Dereham Centre hardness concentration is 235 mg/l. The Iron concentration in the system is slightly above the objective of 0.30 at 0.49 mg/l. Organic Nitrogen levels in the system are at the aesthetic objective of 0.15 mg/l for the parameter. Organic nitrogen can be associated with unpleasant taste and high levels can reduce the effectiveness of chlorine as a disinfectant. 3.4.3. Screening Result and Discussion The parameters in the Dereham Centre Water Supply System that meet the screening threshold are Arsenic, Hardness, Iron and Organic Nitrogen. These parameters are all naturally occurring. They do not affect the treatment process and there is no evidence of upward trending. Page 7
3.5. DRUMBO WATER SUPPLY SYSTEM Issues Evaluation Report 3.5.1. Background The Drumbo Drinking Water System provides water from two wells 32m and 47m deep that are secure groundwater. Disinfection using sodium hypochlorite is the only form of treatment. It is a Large Municipal Water system as defined by Regulation 170/03 and serves a population of approximately 570. 3.5.2. Water Quality substantially alter the water quality. No parameters were found to exceed their MAC. Microbiological results are consistently good at Well 3. Well 2A has had periodic positive low level results for Total Coliforms while not in regular service. This is not uncommon where wells are only periodically pumped as is the case with Well 2A and does not necessarily indicate a concern. The well recently began a rotational production schedule and additional trending will be available shortly. With the exception of Hardness no operational or aesthetic parameters exceed the associated objectives or guidelines. Hardness which has a guideline range from 80 to 100 mg/l is typically exceeded in groundwater systems. The Drumbo hardness concentration is typically between 230 to 330 mg/l. 3.5.3. Screening Result and Discussion The only parameters in the Drumbo Water Supply System that meets the screening threshold are Total Coliform and Hardness. The Total Coliform presence is likely due to the Well being maintained in standby mode and not operated frequently. Hardness is naturally occurring and typical to groundwater sources. It does not affect the treatment process and there is no evidence of upward trending. 3.6. EMBRO WATER SUPPLY SYSTEM 3.6.1. Background The Embro Drinking Water System provides water to customers from 2 wells approximately 60m deep that are secure groundwater. Treatment consists of filtration for iron removal and disinfection. It is a Large Municipal Water system as defined by Regulation 170/03 and serves a population of approximately 820. 3.6.2. Water Quality substantially alter the water quality. No parameters were found to exceed their MAC. Microbiological results are consistently good and indicate no concerns. The Fluoride concentration is typically 1.3 mg/l which is marginally above half of the MAC of 2.4 mg/l. The fluoride is naturally occurring in the groundwater and there is no evidence of upwards trending. Its presence does not impact the treatment process. The system has several operational or aesthetic parameters exceed the associated objectives or guidelines as detailed below. Hardness which has a guideline range from 80 to 100 mg/l is typically exceeded in groundwater systems. The Embro hardness concentration is typically around 430 to 470 mg/l. This Page 8
parameter is naturally occurring in the groundwater and does not a health risk nor does it impact the treatment process. The Sodium concentration is occasionally marginally above the reporting level of 20 mg/l however the most recent results are below the level. All results are well below the objective of 200 mg/l. Chloride levels in the system are quite low suggesting that the sodium is not caused by road salt application but rather is naturally occurring. No increasing trend is evident in the results. Total Dissolved Solids (TDS) levels in the Embro system exceed the objective of 500 mg/l and are around 640 mg/l. TDS is an aesthetic parameter and does not impact health or the treatment process. No increasing trend is evident in the results. The raw water in the system exceeds the objective of 0.3 mg/l for Iron. The raw water is around 1.0 mg/l. Iron is an aesthetic parameter which is removed in the treatment process. Failure of the iron removal would not impact the disinfection process. No increasing trend is evident. 3.6.3. Screening Result and Discussion The parameters in the Embro Water Supply System that meet the screening threshold are Fluoride, Hardness, TDS and Iron. These parameters are all naturally occurring and typical to groundwater sources. They do not affect the treatment process and there is no evidence of upward trending. 3.7. HICKSON WATER SUPPLY SYSTEM 3.7.1. Background The Hickson Drinking Water System obtains water from one 53m deep secure groundwater well. The water is disinfected with sodium hypochlorite and historically has been treated with polyphosphate to sequester iron. No sequestration currently takes place. It is a Small-Municipal Water System as defined by Regulation 170/03 and serves approximately 105 customers. 3.7.2. Water Quality substantially alter the water quality. No parameters were found to exceed their MAC. There are occasionally low level positive results for Total Coliform in the raw water. The Fluoride concentration is typically 1.2 mg/l which is equal to half of the MAC of 2.4 mg/l. The fluoride is naturally occurring in the groundwater and there is no evidence of upwards trending. Its presence does not impact the treatment process. With the exception of Hardness and Iron, no operational or aesthetic parameters exceed the associated objectives or guidelines. Hardness which has a guideline range from 80 to 100 mg/l is typically exceeded in groundwater systems. The Hickson hardness concentration is 263 mg/l. The iron concentration occasionally exceeds the objective of 0.30 mg/l ranging from 0.29 to 0.41. 3.7.3. Screening Result and Discussion The parameters in the Hickson Water Supply System that meet the screening threshold are Total Coliform, Fluoride, Hardness, and Iron. The Total Coliform presence is periodic and levels quite low and thus presents no concern. The other parameters are all naturally occurring and typical to groundwater sources. They do not affect the treatment process and there is no evidence of upward trending. Page 9
3.8. INGERSOLL WATER SUPPLY SYSTEM Issues Evaluation Report 3.8.1. Background The Ingersoll Drinking Water System obtains water from seven bedrock wells between 109 and 140m deep that are all secure groundwater. Each well has its own treatment facility associated with it. The wells and corresponding facilities are listed below: Merritt Street WTF Well 2 Hamilton Road WTF Well 3 Canterbury Street WTF Well 5 West Street WTF Well 7 Dunn s Road WTF Well 8 Thompson Road WTF Well 10 Wallace Line WTF Well 11 (currently offline) All of the facilities provide treatment for hydrogen sulphide removal and chlorination. It is a Large Municipal Water system as defined by Regulation 170/03 and serves a population of approximately 14,000. 3.8.2. Water Quality substantially alter the water quality. No parameters were found to exceed their MAC with the exception of one result for Fluoride at the Wallace Line well of 2.5 mg/l. The Fluoride concentrations at all of the wells are above half of the MAC of 2.4 mg/l and range from 1.4 to 2.4 mg/l. The fluoride is naturally occurring in the groundwater and there is no evidence of upwards trending. Its presence does not impact the treatment process. Microbiological results are consistently good and indicate no concerns at the majority of the wells. There are infrequent, low level positive results for Total Coliform and E.coli in the raw water at Canterbury Street. There have been two detection results of Benzo(a)pyrene in the system. The first result was obtained in 2006 at the West Street well and the second was in 2009 at the Merritt Street well. Both of these samples were treated water and occurred as the treatment facility was being commissioned. In both cases resampling of the water resulted in non-detectable levels. It is believed that the presence was due to the construction at the site and was not indicative of the source water. In 1993 the Ontario Ministry of the Environment, (MOE) conducted an investigation on a private industrial well located near Thomas and Ingersoll Street for trichloroethylene (TCE) contamination. Traces of the chemical were detected in Well 7 at West Street and traces of tetrachloroethylene were detected at Well 2 at Merritt Street. A clean up and monitoring program has been followed by the industry. No TCE has been detected in samples reviewed for this report. The industry s consultant provided test results from 2008 and no was TCE detected. The affected site is regularly monitored. The system has several operational or aesthetic parameters exceed the associated objectives or guidelines as detailed below. Hardness which has a guideline range from 80 to 100 mg/l is typically exceeded in groundwater systems. All of the Ingersoll wells exceed this guideline with concentrations ranging between 282 to 492 mg/l. This parameter is naturally occurring in the groundwater and does not a health risk nor does it impact the treatment process. The Sodium concentration is above the reporting level of 20 mg/l at all wells ranging from 29 to 97 mg/l. All results are well below the objective of 200 mg/l. Chloride levels in the system are Page 10
low suggesting that the sodium is not caused by road salt application but rather is naturally occurring. No increasing trend is evident in the results. Total Dissolved Solids (TDS) levels in the Ingersoll system exceed the objective of 500 mg/l at the Merritt Street, West Street, Dunn s Road and Canterbury Street wells. The concentration ranges from 470 to 863 mg/l. TDS is an aesthetic parameter and does not impact health or the treatment process. No increasing trend is evident in the results. The water in the system exceeds the objective of 0.3 mg/l for Iron at the Wallace, Hamilton and Thompson wells. The concentration is 0.38 mg/l at Wallace, 0.35 mg/l at Hamilton and 0.58 mg/l at Thompson. Iron is an aesthetic parameter and does not interfere with the treatment process. No increasing trend is evident. The aesthetic objective for colour is 5 True Colour Units (TCU). The Dunn s Road well has a value of 10 TCU. All other wells are below the objective. Organic Nitrogen levels in the system are above the aesthetic objective of 0.15 mg/l at Dunn s Road, Canterbury Street and Thompson Road wells. Concentrations range from 0.16 to 0.31 mg/l. Organic nitrogen can be associated with unpleasant taste and high levels can reduce the effectiveness of chlorine as a disinfectant. All wells in Ingersoll exceed the aesthetic objective of 0.05 mg/l for Hydrogen Sulphide. Hydrogen Sulphide is very difficult to collect samples and test for in water as the parameter easily volatilizes into air. Laboratory results for the Ingersoll system have been reported as ranging from 0.26 to 6.02 mg/l. It is believed that the levels in Ingersoll source water are significantly higher than some of these results indicate. Hydrogen Sulphide related odours are the number one complaint historically received by the Operating Authority. Furthermore when not removed from the water prior to disinfection, the Hydrogen Sulphide reacts with chlorine causing a turbidity spike and potentially interrupting the disinfection process. 3.8.3. Screening Result and Discussion The parameters in the Ingersoll Water Supply System that meet the screening threshold at each well are shown in the table below. Parameter Merritt Street Hamilton Road Canterbury Street West Street Dunn s Road Thompson Road Wallace Line Fluoride Tetrachloroethylene Trichloroethylene Hardness TDS Iron Organic Nitrogen Hydrogen Sulphide Total Coliform/E.coli 3.9. INNERKIP WATER SUPPLY SYSTEM 3.9.1. Background The Innerkip Drinking Water System provides water from two wells approximately 35m deep that are secure groundwater. The water is filtered to remove iron and sodium hypochlorite is used for disinfection. It is a Large Municipal Water system as defined by Regulation 170/03 and serves a population of approximately 960. Page 11
3.9.2. Water Quality substantially alter the water quality. No parameters were found to exceed their Maximum Acceptable Concentration (MAC). Microbiological results are consistently good and indicate no concerns. The system has several operational or aesthetic parameters exceed the associated objectives or guidelines as detailed below. Hardness which has a guideline range from 80 to 100 mg/l is typically exceeded in groundwater systems. The system s hardness concentration is typically around 860 mg/l. This parameter is naturally occurring in the groundwater and does not a health risk nor does it impact the treatment process. Total Dissolved Solids (TDS) levels in the system exceed the objective of 500 mg/l and are 1280 to 1370 mg/l. TDS is an aesthetic parameter and does not impact health or the treatment process. No increasing trend is evident in the results. The raw water in the system exceeds the objective of 0.3 mg/l for Iron. The concentration is around 0.97 to 2.13 mg/l. Iron is an aesthetic parameter and does not interfere with the treatment process. No increasing trend is evident. Sulphates have an objective of 500 mg/l and in the Innerkip system, concentrations range from 500 to 720 mg/l. Sulphates are an aesthetic concern and are naturally occurring in the groundwater. There are two additional aesthetic parameters that are normally below their respective objectives but have had one occurrence where they exceeded the limit. These are Organic Nitrogen and Manganese. 3.9.3. Screening Result and Discussion The parameters in the Innerkip Water Supply System that meet the screening threshold are Hardness, TDS, Sulphates, and Iron. These parameters are all naturally occurring and typical to groundwater sources. They do not affect the treatment process and there is no evidence of upward trending. With respect to Organic Nitrogen and Manganese, given the bulk of the results are well below the respective objectives, the parameters not at this time being elevated. 3.10. LAKESIDE WATER SUPPLY SYSTEM 3.10.1. Background The Lakeside Drinking Water System provides water from one well 106m deep that is secure groundwater. The water is treated with sodium hypochlorite for disinfection, and polyphosphate is added to sequester iron. It is a Large Municipal Water system as defined by Regulation 170/03 and serves a population of approximately 400. 3.10.2. Water Quality substantially alter the water quality. No parameters were found to exceed their MAC. Microbiological results are consistently good and indicate no concerns. The Fluoride concentration is typically 1.6 mg/l which is above half of Page 12
the MAC of 2.4 mg/l. The fluoride is naturally occurring in the groundwater and there is no evidence of upwards trending. Its presence does not impact the treatment process. The system has several operational or aesthetic parameters exceed the associated objectives or guidelines as detailed below. Hardness which has a guideline range from 80 to 100 mg/l is typically exceeded in groundwater systems. The Lakeside hardness concentration is typically around 185 mg/l. This parameter is naturally occurring in the groundwater and does not a health risk nor does it impact the treatment process. The aesthetic objective for colour is 5 True Colour Units (TCU). The source typically has a value of 8. There is no evidence of upwards trending and the parameter does not impact the treatment process. The raw water in the system exceeds the objective of 0.3 mg/l for Iron. The concentation is 0.54 mg/l. Iron is an aesthetic parameter and does not interfere with the treatment process. No increasing trend is evident. The Organic Nitrogen level in the system is above the aesthetic objective of 0.15 mg/l with concentrations of 0.28 mg/l. Organic nitrogen can be associated with unpleasant taste and high levels can reduce the effectiveness of chlorine as a disinfectant. There is no history of objectionable taste that is sometimes associated with organic nitrogen. 3.10.3. Screening Result and Discussion The parameters in the Lakeside Water Supply System that meet the screening threshold are Fluoride, Hardness, Colour, Iron and Organic Nitrogen. These parameters are all naturally occurring and typical to groundwater sources. They do not affect the treatment process and there is no evidence of upward trending. 3.11. MOUNT ELGIN WATER SUPPLY SYSTEM 3.11.1. Background The Mount Elgin Drinking Water System obtains water from one well 60m deep that is secure groundwater. The water is disinfected with sodium hypochlorite. It is a Large Municipal Water system as defined by Regulation 170/03 that serves a population of approximately 370. 3.11.2. Water Quality substantially alter the water quality. No parameters were found to exceed their MAC. Microbiological results are consistently good and indicate no concerns. The Fluoride concentration is typically 1.4 mg/l which is marginally above half of the MAC of 2.4 mg/l. The fluoride is naturally occurring in the groundwater and there is no evidence of upwards trending. Its presence does not impact the treatment process. The system has several operational or aesthetic parameters exceed the associated objectives or guidelines as detailed below. Hardness which has a guideline range from 80 to 100 mg/l is typically exceeded in groundwater systems. The Mount Elgin hardness concentration is typically around 220 mg/l. This parameter is naturally occurring in the groundwater and does not a health risk nor does it impact the treatment process. Page 13
The aesthetic objective for colour is 5 True Colour Units (TCU). The source typically has a value below the objective with one result marginally above. There is no evidence of upwards trending and the parameter does not impact the treatment process. The one result is insufficient to screen the parameter as a potential issue. The Sodium concentration is occasionally marginally above the reporting level of 20 mg/l at 24 mg/l. The results are well below the objective of 200 mg/l. Chloride levels in the system are quite low suggesting that the sodium is not caused by road salt application but rather is naturally occurring. No increasing trend is evident in the results. 3.11.3. Screening Result and Discussion The parameters in the Mount Elgin Water Supply System that meet the screening threshold are Fluoride, and Hardness. These parameters are all naturally occurring and typical to groundwater sources. They do not affect the treatment process and there is no evidence of upward trending. 3.12. NORWICH WATER SUPPLY SYSTEM 3.12.1. Background The Norwich Drinking Water System provides water from three wells that are secure groundwater. The Pitcher Street facility treats water from Wells 2 and 5 (34m and 40m deep respectively) with filtration to remove iron and disinfection with sodium hypochlorite. The Main Street facility treats Well 4, 26m deep, with sodium hypochlorite for disinfection and sodium silicate to sequester iron. It is a Large Municipal Water system as defined by Regulation 170/03 and serves a population of approximately 3150. 3.12.2. Water Quality substantially alter the water quality. No parameters were found to exceed their Maximum Acceptable Concentration (MAC). Microbiological results at Well 4 are consistently good. There have been occasional low counts of Total Coliform and E.coli in the raw water at Wells 2 and 5. There doesn t appear to be a regular trend to the results and doesn t indicate a concern. Aesthetic or Operationally significant Parameters The system has several operational or aesthetic parameters exceed the associated objectives or guidelines as detailed below. Hardness which has a guideline range from 80 to 100 mg/l is typically exceeded in groundwater systems. The system s hardness concentration is typically around 305 to 320 mg/l. This parameter is naturally occurring in the groundwater and does not a health risk nor does it impact the treatment process. The raw water in the system exceeds the objective of 0.3 mg/l for Iron. The raw water is around 0.6 mg/l. Iron is an aesthetic parameter and does not interfere with the treatment process. No increasing trend is evident. The Sodium concentration is occasionally marginally above the reporting level of 20 mg/l. The results are well below the objective of 200 mg/l. Chloride levels in the system are quite low suggesting that the sodium is not caused by road salt application but rather is naturally occurring. No increasing trend is evident in the results. The aesthetic objective for colour is 5 True Colour Units (TCU). The source typically has a value below the objective with one result marginally above. There is no evidence of upwards trending and the parameter does not impact the treatment process. The one result is insufficient to screen the parameter as a potential issue. Page 14
The Organic Nitrogen level at Well 5 is above the aesthetic objective of 0.15 mg/l with concentrations of 0.23 mg/l. Organic nitrogen can be associated with unpleasant taste and high levels can reduce the effectiveness of chlorine as a disinfectant. There is no history of objectionable taste that is sometimes associated with organic nitrogen. 3.12.3. Screening Result and Discussion The parameters in the Norwich Water Supply System that meet the screening threshold are Total Coliform for Wells 2 and 5, Hardness, and Iron. The occasional Total Coliform and E.coli counts that are found in Wells 2 and 5 are low level and do not suggest any trending. Hardness and Iron are all naturally occurring and typical to groundwater sources. They do not affect the treatment process and there is no evidence of upward trending. 3.13. OTTERVILLE-SPRINGFORD WATER SUPPLY SYSTEM 3.13.1. Background The Otterville - Springford Drinking Water System provides water to customers from four secure groundwater wells. The system was formally two separate water systems and in 2004 a 3.3 km long transmission main was constructed to connect the communities. Two 13m deep wells are located at the east side of Otterville and two wells, 24m and 26m deep at located at the west end of Springford. The water is treated at each community with sodium hypochlorite for disinfection. It is a Large Municipal Water system as defined by Regulation 170/03 and serves a population of approximately 1580. 3.13.2. Water Quality substantially alter the water quality. As the Springford and Otterville well fields have slightly different water quality, the water quality discussion below considers them separately. 3.13.2.1. Springford Well Field No parameters were found to exceed their MAC. Microbiological results are typically good however occasional low level positive results for Total Coliform have been found when one of the wells is operated in standby mode. The Fluoride concentration is typically 1.65 mg/l which is above half of the MAC of 2.4 mg/l. The fluoride is naturally occurring in the groundwater and there is no evidence of upwards trending. Its presence does not impact the treatment process. The system has several operational or aesthetic parameters exceed the associated objectives or guidelines as detailed below. The Sodium concentration at the well field ranges from 44 to 47 mg/l which is above the reporting level of 20 mg/l but well below the objective of 200 mg/l. Chloride levels in the system are quite low suggesting that the sodium is not caused by road salt application but rather is naturally occurring. No increasing trend is evident in the results. The aesthetic objective for colour is 5 True Colour Units (TCU). The source has a value of 8 TCU. There is insufficient evidence to comment on any trending. The parameter does not impact the treatment process. 3.13.2.2. Otterville Well Field No parameters were found to exceed their MAC. Microbiological results are typically good however occasional low level positive results for Total Coliform have been found when one of Page 15
the wells is operated in standby mode. In 2007, there was a six month period where Total Coliform counts were higher than usual and there were occasional low level E.coli positive results as well. Following rehabilitation of the well in January 2008, the levels returned to normal. The Fluoride concentration is typically well below the half of the MAC of 2.4 mg/l. One result was obtained which is above the half MAC however it is expected to be a sampling or laboratory error. The system has several operational or aesthetic parameters exceed the associated objectives or guidelines as detailed below. Hardness which has a guideline range from 80 to 100 mg/l is typically exceeded in groundwater systems. The system s hardness concentration is between 247 and 336 mg/l. This parameter is naturally occurring in the groundwater and does not a health risk nor does it impact the treatment process. The Sodium concentration at the well field ranges from 28 to 44 mg/l which is above the reporting level of 20 mg/l but well below the objective of 200 mg/l. Chloride levels in the system are quite low suggesting that the sodium is not caused by road salt application but rather is naturally occurring. No increasing trend is evident in the results. The Organic Nitrogen level in the system is above the aesthetic objective of 0.15 mg/l with concentrations of 0.29 mg/l. Organic nitrogen can be associated with unpleasant taste and high levels can reduce the effectiveness of chlorine as a disinfectant. There is no history of objectionable taste that is sometimes associated with organic nitrogen. 3.13.3. Screening Result and Discussion The parameters in the Springford Well Field that meet the screening threshold are Total Coliform, Fluoride and Colour. The Total Coliform results are likely due to infrequent operation of the well when it is in standby mode. The remaining parameters are all naturally occurring and typical to groundwater sources. They do not affect the treatment process and there is no evidence of upward trending. The parameters in the Otterville Well Field that meet the screening threshold are Hardness, and Organic Nitrogen. The Total Coliform results are likely due to infrequent operation of the well when it is in standby mode. The remaining parameters are all naturally occurring and typical to groundwater sources. They do not affect the treatment process and there is no evidence of upward trending. 3.14. PLATTSVILLE WATER SUPPLY SYSTEM 3.14.1. Background The Plattsville Drinking Water System provides water from 2, 15m deep wells that are secure groundwater. The water is treated with sodium hypochlorite for disinfection, and sodium silicate is added to sequester iron. It is a Large Municipal Water system as defined by Regulation 170/03 and serves a population of approximately 1160. 3.14.2. Water Quality substantially alter the water quality. No parameters were found to exceed their Maximum Acceptable Concentration (MAC). Microbiological results are consistently good. Page 16
The system has several operational or aesthetic parameters exceed the associated objectives or guidelines as detailed below. Hardness which has a guideline range from 80 to 100 mg/l is typically exceeded in groundwater systems. The system s hardness concentration is very high, typically around 1000 to 1340 mg/l. This parameter is naturally occurring in the groundwater and does not a health risk nor does it impact the treatment process. Total Dissolved Solids (TDS) levels in the system exceed the objective of 500 mg/l and are 1620 to 1880 mg/l. TDS is an aesthetic parameter and does not impact health or the treatment process. No increasing trend is evident in the results. The raw water in the system exceeds the objective of 0.3 mg/l for Iron. The raw water is around 0.48 to 0.6 mg/l. Iron is an aesthetic parameter and does not interfere with the treatment process. No increasing trend is evident. Sulphates have an objective of 500 mg/l and in the Innerkip system, concentrations range from 870 to 1000 mg/l. Sulphates are an aesthetic concern and are naturally occurring in the groundwater. The system typically exceeds the aesthetic objective of 0.05 mg/l for Manganese with concentrations in the 0.06 0.08 mg/l range. There is no increasing trend to the concentration and its presence does not interfere with the treatment process. 3.14.3. Screening Result and Discussion The parameters in the Plattsville System that meet the screening threshold are Hardness, TDS, Iron, Manganese and Sulphates. These parameters are all naturally occurring and do not affect the treatment process. There is no evidence of upward trending. 3.15. TAVISTOCK WATER SUPPLY SYSTEM 3.15.1. Background The Tavistock Drinking Water System provides water from three wells 19.5m, 48m and 61.5m deep that are secure groundwater. The water is treated with sodium hypochlorite for disinfection and sodium silicate is added to sequester iron. It is a Large Municipal Water system as defined by Regulation 170/03 and serves a population of approximately 2300. 3.15.2. Water Quality substantially alter the water quality. No parameters were found to exceed their Maximum Acceptable Concentration (MAC). Microbiological results are consistently good in Wells 1 and 3. Well 2, which is a standby well, has occasional low level positive results for Total Coliform in the raw water. The system has several operational or aesthetic parameters exceed the associated objectives or guidelines as detailed below. Hardness which has a guideline range from 80 to 100 mg/l is typically exceeded in groundwater systems. The system s hardness concentration is typically around 280 to 380 mg/l. This parameter is naturally occurring in the groundwater and does not a health risk nor does it impact the treatment process. Page 17
The raw water in each of the three wells exceed the objective of 0.3 mg/l for Iron. The concentrations range from 0.6 to 0.9 mg/l. Iron is an aesthetic parameter and does not interfere with the treatment process. No increasing trend is evident. The Organic Nitrogen level in the system is above the aesthetic objective of 0.15 mg/l with concentrations of 0.3 mg/l. Organic nitrogen can be associated with unpleasant taste and high levels can reduce the effectiveness of chlorine as a disinfectant. There is no history of objectionable taste that is sometimes associated with organic nitrogen. 3.15.3. Screening Result and Discussion The parameters in the Tavistock Water Supply System that meet the screening threshold are Total Coliform, Hardness, Iron and Organic Nitrogen. Total Coliform presence is likely due to the fact that Well 2 typically operates in standby mode. The remaining parameters are all naturally occurring, they do not affect the treatment process and there is no evidence of upward trending. 3.16. THAMESFORD WATER SUPPLY SYSTEM 3.16.1. Background The Thamesford Drinking Water System provides water to customers from 3 well sources. Wells 1 and 2 are 9.4m and 14m deep respectively and are Groundwater Under Direct Influence of Surface Water (GUDI) with effective in-situ filtration. Well 3 is a secure 78m deep groundwater well. Treatment for all the wells consists of filtration for iron and manganese removal followed by disinfection with Ultra Violet (UV) irradiation and sodium hypochlorite. It is a Large Municipal Water system as defined by Regulation 170/03 and serves a population of approximately 1970. 3.16.2. Water Quality substantially alter the water quality. The GUDI wells (1 & 2) are located adjacent to the Thames River and have different water quality characteristics than Well 3 as shown in the sections below. Microbiological results are consistently good at Wells 1 and 3. Well 2 has occasional low level Total Coliform and E.coli results due to being operated infrequently. The only health related parameters to exceed the half MAC screening thresholds are Nitrate in Wells 1 and 2 and Fluoride in Well 3. Nitrate levels in the wells have been regularly monitored since 1999 and remained in a similar range. In 2008 the results ranged from 4.71 to 9.76 mg/l. The most recent result above the MAC of 10 mg/l was one result of 10.2 mg/l reported in December 2007. Nitrate is not typically a naturally occurring parameter in groundwater at levels around the MAC and may be from nutrient application, septic systems or sewage effluent. The Fluoride concentration in Well 3 ranges from 1.5 to 2.2 mg/l which is above half of the MAC of 2.4 mg/l. The fluoride is naturally occurring in the groundwater and there is no evidence of upwards trending. Its presence does not impact the treatment process. The system has several operational or aesthetic parameters exceed the associated objectives or guidelines as detailed below. Hardness which has a guideline range from 80 to 100 mg/l is typically exceeded in groundwater systems. The system s hardness concentration is typically around 365 to 550 mg/l. This parameter is naturally occurring in the groundwater and does not a health risk nor does it impact the treatment process. The Sodium concentration in all wells is above the reporting level of 20 mg/l. In Wells 1 and 2 the concentration ranges from 22 to 27 mg/l and in Well 3 it ranges from 45 to 51 mg/l. These levels are well below the objective of 200 mg/l. Chloride levels in the system are also quite low Page 18
suggesting that the sodium is not caused by road salt application but rather is naturally occurring. No increasing trend is evident in the results. The raw water in wells 1 and 2 exceed the objective of 0.05 mg/l for Manganese with concentrations of 0.19 mg/l. Manganese is an aesthetic parameter and no increasing trend is evident. The treatment facility removes manganese through an oxidation and filtration process. Failure of this process could potentially result in decreased clarity of the water which would impact the effectiveness of the UV disinfection. Total Dissolved Solids (TDS) levels in Well 3 exceed the objective of 500 mg/l and ranges from 628 to 827 mg/l. TDS is an aesthetic parameter and does not impact health or the treatment process. The Organic Nitrogen levels in Wells 1 and 3 are above the aesthetic objective of 0.15 mg/l with concentrations ranging from 0.16 to 0.19 mg/l. Organic nitrogen can be associated with unpleasant taste and high levels can reduce the effectiveness of chlorine as a disinfectant. There is no history of objectionable taste that is sometimes associated with organic nitrogen. 3.16.3. Screening Result and Discussion The parameters in the Thamesford Water Supply System that meet the screening threshold are Total Coliform and E.coli, Fluoride, Nitrate, Hardness, Manganese, TDS and Organic Nitrogen. With the exception of the bacteriological parameters and Nitrate, these parameters are naturally occurring and typical to groundwater sources. The bacteriological positive results are likely due to the fact that Well 2 is used as a standby well and not operated frequently. Nitrate at the levels in the Thamesford system are likely anthropogenic in source. 3.17. TILLSONBURG WATER SUPPLY SYSTEM 3.17.1. Background The Tillsonburg Drinking Water System is a Large Municipal Water system as defined by Regulation 170/03 and serves a population of approximately 16,400. It provides water to customers from 10 source wells. Wells 1A, 2, 4, 5, 7, 9 and 10 are GUDI wells with effective insitu filtration. Wells 6A, 11 and 12 are secure groundwater wells. There are currently four different treatment schemes used in the system summarized as follows: Well 6A and 12, have a treatment process consisting solely of chlorination. GUDI Wells 4 and 5 have disinfection treatment with UV and chlorine gas. GUDI Wells 1A, 2, 9, 10, and 11 are treated with filtration to remove iron, disinfection treatment with UV and chlorine gas. GUDI Well 7 is currently only used for emergency backup and has disinfection treatment with sodium hypochlorite and iron sequestering. Plans for the well include a transmission main connection to a GUDI treatment facility. 3.17.2. Water Quality substantially alter the water quality. For the purposes of water quality characteristics the wells can be grouped into six different wellfields; Mall Road (Wells 1A & 2), North Street (Wells 4 and 5), Well 6A, Well 7, Bell Mill Sideroad (Wells 9, 10 and 11) and Well 12. Microbiological results are consistently good at all ten wells. The health related parameters to exceed the half MAC screening threshold are Nitrates, Fluoride and Arsenic as described below. Nitrate levels in Wells 4, 5 and 12 are above half of the MAC of 10 mg/l. In Well 12, the concentration is right at the half MAC threshold ranging from 4.9 to 5.9 mg/l and does not show Page 19
an increasing trend. The nitrate levels at the North Street well field are higher and are monitored regularly. In 2008 the concentration ranged from 6.18 to 9.24 mg/l. In January 2005 two results were received above the MAC at 10.0 and 10.2 mg/l. There is no evidence of upward trending. Nitrate is not typically a naturally occurring parameter in groundwater at levels around the MAC and may be from nutrient application, septic systems or sewage effluent. Arsenic levels in Well 7 have been above half of the MAC of 0.025 mg/l once. Concentrations range from 0.003 mg/l to 0.017 mg/l. There does not appear to be an increasing trend in the results. The Fluoride concentration at Well 6 is typically 1.5 mg/l which is above half of the MAC of 2.4 mg/l. The fluoride is naturally occurring in the groundwater and there is no evidence of upwards trending. Its presence does not impact the treatment process. The system has several operational or aesthetic parameters exceed the associated objectives or guidelines as detailed below. Hardness which has a guideline range from 80 to 100 mg/l is typically exceeded in groundwater systems. The system s hardness concentration is typically around 262 to 320 mg/l. Only Well 6 does not exceed the guideline. This parameter is naturally occurring in the groundwater and does not a health risk nor does it impact the treatment process. The Sodium concentration at the North Street Wellfield and Wells 6A and 7 is above the reporting level of 20 mg/l. North Street concentrations range from 16 to 15 mg/l, Well 6A ranges from 41 to 46 mg/l and Well 7 ranges from 81 to 89 mg/l. These levels are well below the objective of 200 mg/l. Chloride levels in the system are also low suggesting that the sodium is not caused by road salt application but rather is naturally occurring. No increasing trend is evident in the results. The raw water in Mall Road wellfield marginally exceed the objective of 0.05 mg/l for Manganese with concentrations around 0.06 to 0.08 mg/l. Concentrations in the Bell Mill wellfield are slightly higher and exceed the objective with concentations ranging from 0.10 to 0.16 mg/l. Manganese is an aesthetic parameter and no increasing trend is evident. The treatment facility removes manganese through an oxidation and filtration process. Failure of this process could potentially result in decreased clarity of the water which would impact the effectiveness of the UV disinfection. The raw water at the Mall Road and Bell Mill wellfields and Well 7 exceed the objective of 0.3 mg/l for Iron. The concentrations are 0.8 to 1.2 mg/l. Iron is an aesthetic parameter and no increasing trend is evident. The treatment facilities remove iron through an oxidation and filtration process. Failure of this process could potentially result in decreased clarity of the water which would impact the effectiveness of the UV disinfection. The Organic Nitrogen level in the system is above the aesthetic objective of 0.15 mg/l at Wells 2, 4, 6, 7, and 11. Concentrations range from 0.18 to 0.42 mg/l. Organic nitrogen can be associated with unpleasant taste and high levels can reduce the effectiveness of chlorine as a disinfectant. There is no history of objectionable taste that is sometimes associated with organic nitrogen. 3.17.3. Screening Result and Discussion The parameters in the Tillsonburg Water Supply System that meet the screening threshold are summarized in the table below. Page 20
Parameter Mall Road North St. Well 6A Well 7 Bell Mill Sideroad Well 12 Fluoride Arsenic Nitrates Hardness Iron Organic Nitrogen Manganese 3.18. WOODSTOCK WATER SUPPLY SYSTEM 3.18.1. Background The Woodstock Drinking Water System is a Large Municipal Water system as defined by Regulation 170/03 and serves a population of approximately 36,000. It provides water to customers from ten well sources. Six of the wells (1, 2, 3, 4, 5 and 8) GUDI with effective in-situ filtration and four (6, 7, 9 and 11) are secure groundwater wells. For the purposes of water quality there are five different well fields; Thornton (Wells 1, 3, 5, 8 and 11), Tabor (Wells 2 and 4), Well 6, Well 7 and Well 9. The bulk of the City s water is taken from the Thornton and Tabor wellfields. Treatment for the Thornton and Taber wells consists of UV and chlorination for disinfection. Wells 6 and 9 have disinfection only and Well 7 has aeration for hydrogen sulphide removal and disinfection. 3.18.2. Water Quality substantially alter the water quality. Microbiological results are consistently good at all ten wells. The only health related parameters to exceed the half MAC screening threshold at any of the wells are Nitrates and Fluoride as described below. Nitrate levels in Wells 1, 2, 3, 5, 8 and 11 are routinely above half of the MAC of 10 mg/l. In Well 4, the concentration is typically below the half MAC threshold but has occasionally been marginally above the threshold. The nitrate levels are monitored regularly from the raw water as well as the treated point of entry to the system. In 2008 the concentration ranged from 3.7 to 11.5 mg/l in the raw water. Well 3 typically has the highest Nitrate concentrations. Nitrate is not typically a naturally occurring parameter in groundwater at levels around the MAC and may be from nutrient application, septic systems or sewage effluent. The Fluoride concentration at Well 9 is 1.4 mg/l which is above half of the MAC of 2.4 mg/l. The fluoride is naturally occurring in the groundwater and there is no evidence of upwards trending. Its presence does not impact the treatment process. The system has several operational or aesthetic parameters exceed the associated objectives or guidelines as detailed below. Hardness which has a guideline range from 80 to 100 mg/l is typically exceeded in groundwater systems. The system s hardness concentration is typically between 349 and 567 mg/l. This parameter is naturally occurring in the groundwater and does not a health risk nor does it impact the treatment process. Page 21
The Sodium concentration in Wells 6, 7 and 9 is above the reporting level of 20 mg/l and ranges from 36 to 53 mg/l. These levels are well below the objective of 200 mg/l. Chloride levels in the system are also quite low suggesting that the sodium is not caused by road salt application but rather is naturally occurring. No increasing trend is evident in the results. The concentration of Manganese in Well 7 is equal to the objective of 0.05 mg/l. It is naturally occurring and does not interfere with the treatment process. Total Dissolved Solids (TDS) levels in Wells 6, 7 and 9 exceed the objective of 500 mg/l. TDS is an aesthetic parameter and does not impact health or the treatment process. Well 6, 7 and 9 exceed the objective of 0.3 mg/l for Iron. The concentration is around 0.6 to 3.8 mg/l. Iron is an aesthetic parameter and does not interfere with the treatment process. No increasing trend is evident. The Organic Nitrogen level in the system is above the aesthetic objective of 0.15 mg/l at Wells 6, 7, 8, 9 and 11. Concentrations range from 0.37 to 0.75 mg/l. Organic nitrogen can be associated with unpleasant taste and high levels can reduce the effectiveness of chlorine as a disinfectant. There is no history of objectionable taste that is sometimes associated with organic nitrogen. Wells 7 and 9 exceed the aesthetic objective of 0.05 mg/l for Hydrogen Sulphide. Hydrogen Sulphide is very difficult to collect samples and test for in water as the parameter easily volatilizes into air. Laboratory results are reported as being right around the objective. It is believed that the levels in wells are higher than the results indicate. Complaints related to Hydrogen Sulphide odours have been received from Well 7. Well 9 combines with water from other wells prior to entering the distribution system and odours are not noticeable. 3.18.3. Screening Result and Discussion The parameters in the Woodstock Water Supply System that meet the screening threshold are summarized in the table below. Parameter Thornton Tabor Well 6 Well 7 Well 9 Fluoride Nitrates Hardness Iron Organic Nitrogen TDS Hydrogen Sulphide Manganese 3.19. SUMMARY OF SCREENED POTENTIAL ISSUES The following table summarizes the potential issues that have met the screening thresholds as described in detail in the previous sections. Page 22
Flouride Arsenic Summary of Screened Potential Issues Nitrate Trihalomethanes Bacteriological Trichloroethylene Tetrachloroethylene Hardness Type of Threshold MAC MAC MAC MAC MAC MAC MAC OG AE AE AE AE AE AE AE AE Beachville Bright Brownsville Dereham Centre Drumbo Embro Hickson Ingersoll Merritt (Well 2) Hamilton (Well 3) Canterbury (Well 5) West (Well 7) Thompson (Well 10) Dunn's (Well 8) Wallace (Well 11) Innerkip Lakeside Mount Elgin Norwich Sodium Iron Manganese TDS Colour Sulphates Sulphides Organic Nitrogen LEGEND Wells 2 and 5 Well 4 exceeds MAC, AO, OG Otterville-Springford exceeds 1/2 MAC Otterville exceeds reporting level, not screened Springford Plattsville Tavistock Thamesford Wells 1 and 2 Well 3 Tillsonburg Mall Rd (Wells 1A & 2) North St. (Wells 4 &5) Well 6A Well 7 Bell Mill (Wells 9, 10 & 11) Well 12 Woodstock Thornton Tabor Well 6 Well 7 Well 9
4. ISSUE EVALUATION PARAMETER SPECIFIC The following section provides a brief discussion of the screened potential issues for each system and whether they constitute an issue taking into consideration the criteria established in section 2.6. 4.1. FLUORIDE Fluoride has been screened as a potential issue in ten systems (Brownsville, Embro, Hickson, Ingersoll, Lakeside, Mount Elgin, Otterville-Springford, Thamesford, Tillsonburg and Woodstock). In all cases fluoride is a naturally occurring parameter and concentrations are below the health related MAC. There is no indication of increasing trending and no impact on any of the treatment processes. Therefore Fluoride is not considered an issue in any Oxford County Water System. 4.2. ARSENIC The screening process identified Arsenic as a potential issue in Dereham Centre and Well 7 in the Tillsonburg system. The parameter is naturally occurring and is at a concentration right around the half MAC. There is no evidence of increasing trending and therefore Arsenic would not be considered an issue however, it is anticipated that the province will soon adopt the Health Canada limit of 0.010 mg/l as a MAC. Both wells exceed this concentration and therefore the County considers it an issue. 4.3. TRIHALOMETHANES Trihalomethanes are a group of chemicals that are health related and are present in treated water due to chlorine reacting with naturally occurring organic material during the disinfection process. Levels are consistently around the half MAC were found in Brownsville. As they do not appear to be increasing it is not an issue in the system. 4.4. NITRATE Nitrate at concentrations above the half MAC were found in Thamesford, Tillsonburg and Woodstock. The specifics for each system are presented below. 4.4.1. Thamesford Wells 1 and 2 The Nitrate found in Thamesford s Wells 1 and 2 is at a level that is likely anthropogenic. The treatment process combines the high nitrate water with water from Well 3 to control nitrate levels in the distribution system. If Well 3 was to fail or be offline for long periods of time, supply could be compromised. For this reason nitrate is an issue in the Thamesford system. 4.4.2. Tillsonburg North Street Wellfield (Wells 4 and 5) Nitrate was screened as a potential issue at the North Street Wellfield. The Nitrate found in Wells 4 and 5 is at a level that is likely anthropogenic. The planned treatment process will combine the high nitrate water with water from Well 7 to control nitrate levels in the distribution system. Wells 4 and 5 are large producing wells and any increase of nitrate at this location could compromise the supply and therefore Nitrate is an issue in the North Street wellfield. 4.4.3. Tillsonburg Well 12 The concentration of Nitrates found in Well 12 at Tillsonburg is right around the half MAC. There is no evidence of increasing trending and therefore is not being identified as an issue. 4.4.4. Woodstock Thornton Wellfield (Wells 1, 3, 5, 8 and 11) Nitrates were screened as a potential issue in the Woodstock System s Thornton wellfield. The presence of nitrate in this wellfield has been studied in depth for over a decade. Research by the Page 23
University of Waterloo has confirmed that the presence of the parameter is likely due to historical nutrient application practices on the surrounding agricultural fields. Nitrate concentrations at the wells have been increasing and the research has found that concentrations within the Wellhead Protection Area are higher than those currently seen in the production wells. Currently water from this wellfield is combined with water from the Taber wellfield to ensure nitrate levels in the distribution system remain low. The wellfield represents a significant portion of the total supply to the Woodstock system and therefore Nitrate has been identified as an issue in the Thornton Wellfield. 4.4.5. Tabor Wellfield (Wells 2 and 4) Nitrates were screened as potential issue for the Woodstock Tabor wellfield. Levels at this wellfield are significantly lower than those seen in the Thornton wellfield and are around half of the MAC. There is evidence to suggest that concentrations are trending upwards. The wellfield contains two highly productive wells that are a main supply of water to the system. Increased levels of nitrate in this wellfield could reduce the effectiveness of blending the water with Thornton to lower the overall nitrate concentration in the system. Therefore Nitrate is an issue in the Tabor wellfield. 4.5. BACTERIOLOGICAL PARAMETERS Total Coliform and/or E.coli was screened as a potential issue in six systems (Drumbo, Hickson, Ingersoll, Otterville-Springford, Tavistock and Thamesford). In all cases the results were found occasionally and at very low levels. Typically this is due to infrequent pumping of the well while it is in rotational or standby operation. None of the findings are significant enough to warrant being elevated to an issue. 4.6. TRICHLOROETHYLENE AND TETRACHLOROETHYLENE Trichloroethylene and Tetrachloroethylene were observed once in the Ingersoll system over 15 years ago in trace amounts. All recent test results for these parameters have been non-detectable and therefore the parameters are not an issue for the system. 4.7. HARDNESS Hardness was identified as a potential issue at every system. Hardness is naturally occurring and commonly elevated in groundwater sources. It does not interfere with the treatment process and is therefore not an issue. 4.8. SODIUM Sodium above the reporting limit of 20 mg/l was found in nine systems (Bright, Brownsville, Ingersoll, Mount Elgin, Norwich, Otterville-Springford, Thamesford, Tillsonburg and Woodstock). All concentrations observed were well below the aesthetic objective of 200 mg/l. Concentrations in the range observed are common in groundwater supplies and none of the systems were screened as having sodium as a potential issue. 4.9. IRON AND MANGANESE Twelve systems (Bright, Dereham Centre, Embro, Hickson, Ingersoll, Innerkip, Lakeside, Norwich, Plattsville, Tavistock, Tillsonburg and Woodstock) were screened as having Iron as a potential issue. Manganese was screened as a potential issue in five systems (Ingersoll, Plattsville, Thamesford, Tillsonburg and Woodstock). Page 24
Iron and Manganese are aesthetic parameters that are commonly found in groundwater supplies. There presence does not represent an issue in secure groundwater. The parameters are present in the following GUDI wells: Thamesford Wells 1 and 2 Manganese only Tillsonburg Mall Road Wellfield (Wells 1A and 2) Iron and Manganese Tillsonburg Bell Mill Sideroad (Wells 9, 10 and 11) Iron and Manganese At the three wellfields both Iron and Manganese are removed from the raw water through oxidization and filtration prior to disinfection with UV. If these parameters were not removed the clarity of the water and therefore the ability of the UV light to penetrate the water could be decreased. This could potentially compromise the effectiveness of the enhanced disinfection required for the GUDI well supplies. Therefore Iron and Manganese are issues in the Tillsonburg Mall Road and Bell Mill wellfields and Manganese is an issue in the Thamesford system. 4.10. TDS, COLOUR AND SULPHATES TDS, Colour and Sulphates are all naturally occurring parameters aesthetic parameters that are common to groundwater supplies. TDS was found in seven systems (Bright, Embro, Ingersoll, Innerkip, Plattsville, Thamesford and Woodstock), Colour was found in five systems (Brownsville, Ingersoll, Lakeside, Mount Elgin and Otterville-Springford) and Sulphates were found in the Innerkip and Plattsville systems. The parameters do not effect treatment and therefore are not considered issues. 4.11. HYDROGEN SULPHIDE Hydrogen Sulphide in the source water of the Ingersoll system is quite high and can cause significant water quality and treatment issues when the filtration systems are not in service. For this reason hydrogen sulphide is being identified as an Issue for the system even though it is naturally occurring and does not have a health related impact. 4.12. ORGANIC NITROGEN The Organic Nitrogen was screened as a potential issue in eight systems (Ingersoll, Lakeside, Norwich, Otterville-Springford, Tavistock, Thamesford, Tillsonburg and Woodstock). It is an aesthetic parameter and can be associated with unpleasant taste. High levels of Organic Nitrogen can reduce the effectiveness of chlorine as a disinfectant. There is no history of taste complaints associated with organic nitrogen or disinfection difficulties at any of the systems. Therefore it is not an issue. 4.13. SUMMARY OF ISSUE IDENTIFICATION The majority of the potential issues identified in Section 3 of this report are non-health related parameters that are naturally occurring and typical to groundwater supplies. As shown on the table below the issues identified are Arsenic in the Dereham Centre and Tillsonburg systems, Nitrate in the Thamesford, Tillsonburg and Woodstock systems, Hydrogen Sulphide in the Ingersoll system, and Iron and Manganese were present in a GUDI treatment environment (Thamesford and Tillsonburg). Page 25
Flouride Arsenic Trihalomethanes Nitrates Summary of Issues Bacteriological Trichloroethylene Tetrachloroethylene Type of Threshold MAC MAC MAC MAC MAC MAC MAC OG AE AE AE AE AE AE AE AE Beachville Bright Brownsville Dereham Centre Drumbo Embro Hickson Ingersoll Merritt (Well 2) Hamilton (Well 3) Canterbury (Well 5) West (Well 7) Thompson (Well 10) Dunn's (Well 8) Wallace (Well 11) Hardness Sodium Iron Manganese TDS Colour Sulphates Sulphides Organic Nitrogen Innerkip Lakeside Mount Elgin LEGEND Norwich Wells 2 and 5 Identified Issue Well 4 Otterville-Springford Otterville Springford Plattsville Tavistock Thamesford Wells 1 and 2 Well 3 Tillsonburg Mall Rd (Wells 1A & 2) North St. (Wells 4 &5) Well 6A Well 7 Bell Mill (Wells 9, 10 & 11) Well 12 Woodstock Thornton Tabor Well 6 Well 7 Well 9