Appendix G

Table G.1. Explanations as to how the parameter values were converted into performance scores

Variables

Performance points attribution details

Agricultural land use

The performance scores have been attributed based on the QME database classification mentioned in Table 2.1. For utilities located in municipalities with an annual phosphorus balance below zero (P2O5 < 0 kg/ha/year), that is, municipalities with extremely low agricultural pressure, the maximum score (e.i., 100 performance points) has been attributed. For utilities located in municipalities with P2O5 = 0 kg/ha/year, 50 performance points have been allotted. Utilities with slight phosphorus surplus, but less than the 20 kg/ha/year QME established threshold, received 25 points. And utilities located in municipalities in surplus situation (i.e., with P2O5 > 20 kg/ha/year or located in administratively designated as “surplus” municipalities) scored no performance points (i.e., 0 points) on that variable.

Raw water TOC

In the 2001 QDWR, a raw water TOC concentration of 3 mg/L was given as an indication for surface water utilities, for which filtration was not becoming compulsory. This value has been considered equalling the 50th percentile of performance points (i.e., C50 or median) on that variable. Based on that assumption, performance scores have been attributed to studied utilities as follows: 100 points for utilities with C1≤TOC≤C20, as average raw water TOC concentration (mg/L); 75 points to utilities with C20<TOC≤C40. Utilities with C40<TOC≤C60 received 50 points, and those averaging C60<TOC≤C80 received 25 points. C1, C20, C40, C60 and C80 equalled 0.06, 1.2, 2.4, 3.6, and 4.8 mg/L, respectively. None of the utilities exhibited average raw water TOC concentration exceeding the latter value.

Raw water turbidity

In the 2001 QDWR, a raw water turbidity threshold of 5 ntu was mentioned as a maximum for surface water utilities, for which filtration was not becoming compulsory. Thus, 5 ntu has been considered equalling the 100th percentile of performance points (i.e., C100 or maximum). Based on that consideration, performance scores have been allotted to utilities as follows: 100 points for utilities with C1≤turbidity≤C20, as average raw water turbidity (ntu); 75 points to utilities with C20<turbidity≤40. C1, C20, C40 equalled 0.05, 1, and 2 ntu, respectively. None of studied utilities had an average raw water turbidity exceeding 1.5 ntu.

Table G.1. Explanations as to how the parameter values were converted into performance scores (continued-1)

Variables

Performance points attribution details

Raw water total coliforms

In the 2001 QDWR, a raw water total coliform count of 100 cfu/100 mL was given as an indication for surface water utilities, for which filtration was not becoming compulsory. This value has been considered equalling the 50th percentile of performance points on that variable. Thus, performance scores have been attributed to studied utilities as follows: 100 points for utilities with C1≤total coliform counts≤C20, as average raw water total coliform counts (cfu/mL); 75 points to utilities with C20<total coliform counts≤C40. C1, C20, C40 equalled 2, 40, and 80 cfu/100 mL, respectively. None of studied utilities had average raw water total coliform counts exceeding 41 cfu/100 mL.

Raw water HPC bacteria

The 2001 QDWR gave a maximum of 500 cfu/mL at distribution system extremity for HPC bacteria. Since not distributed but rather raw water is concerned herein, this threshold is used only as an indication, to allow for relative performance comparisons between studied utilities. Therefore, the 500 cfu/mL mark has been considered as equalling the C20 of performance points on that variable. Consequently, performance scores have been allotted as follows: 100 points to utilities with C1≤HPC bacteria counts≤C20; 75 points to utilities with C20<HPC bacteria counts≤C40; 50 points to those with C40<HPC bacteria counts≤C60; 25 points to utilities with C60<HPC bacteria counts≤C80; and 0 points to those with HPC bacteria counts>C80. C1, C20, C40, C60, and C80 equalled 25, 500, 1000, 1500, and 2000, respectively.

Raw water atypical bacteria

The 2001 QDWR gave a maximum of 200 cfu/100mL in the distribution system for atypical bacteria. Since not distributed but rather raw water is concerned herein, this threshold is used only as an indication for comparison purposes. Thus, the 200 cfu/100mL mark has been considered as equalling the C50 of performance points on that variable. Consequently, performance scores have been allotted as follows: 100 points to utilities with C1≤atypical bacteria counts≤C20; 75 points to utilities with C20< atypical bacteria counts≤C40; 50 points to those with C40< atypical bacteria counts≤C60; 25 points to utilities with C60< atypical bacteria counts≤C80; and 0 points to those with atypical bacteria counts>C80. C1, C20, C40, C60, and C80 equalled 4, 80, 160, 240, and 320, respectively.

Table G.1. Explanations as to how the parameter values were converted into performance scores (continued-2)

Variables

Performance points attribution details

CT value

In the United States Environmental Protection Agency Guidance Manual entitled “Alternative Disinfectants and Oxidants” (USEPA, 1999), it was mentioned, “... 4-log virus inactivation is achievable with a CT of 15 to 60 mg·min/L for most temperatures. These values have been considered as equalling respectively C3 and C12 of performance points on that variable. ” Since all ten utilities being studied have chlorination as the only treatment applied, it appears reasonable to think that this is the objective they should pursue, taking into account the fact that the 3-log Giardia cyst inactivation and the 2-log Cryptosporidium oocyst inactivation (all of which are required for surface water utilities in 2001 QDWR) are beyond reach with chlorination alone. Hence, very conservatively, performance scores have been attributed as indicated herein: 100 points to utilities with CT≥C60 mg·min/L; 75 points to those with C30≤CT<C60; 50 points to utilities with C15≤CT<C30; 25 points to those with C5≤CT<C15; and 0 points to utilities with CT<C5. Note that C5, C15, C30, and C60 equalled 25, 75, 150, and 300, respectively.

Residual chlorine checking frequency

This information was obtained from utility managers before 2001 QDWR’s full implementation (October, 2001). Seven out the ten studied utilities used to check for residual chlorine on a daily basis (see Appendix F). The three others used to measure residual chlorine only once in two days. Thus, on a relative performance basis, 100 points have been allotted to those applying daily residual chlorine measurement, while those doing such a measurement once in two days received 50 points.

Residual chlorine checkpoints appropriateness

Judging by indications given in 2001 QDWR, an adequate residual chlorine controlling through the whole distribution system requires having checkpoints (or sampling points) at least in two locations, that is, the chlorination facility outlet (or storage tank outlet, if this tank is located at facility after the point of chlorine injection) and the distribution system extremity or thereabouts. Nine utility managers declared using to check for residual chlorine only at the facility (with one at the storage tank outlet), while only one utility had residual chlorine sampling points at facility and nearby system extremities. The only utility that checked for residual chlorine at both facility and extremities scored 100 points on that variable; all other nine received 50 points.

Table G.1. Explanations as to how the parameter values were converted into performance scores (continued-3)

Variables

Performance points attribution details

Utility age

According to Fougères et al. (1998), the useful life of a drinking water distribution pipe can rarely go over one hundred years. So, this number has been taken as reference value, with C1 equalling 1 year and C100 being 100 years. Thus, utilities that had age≤C20 scored 100 points on that variable; 75 points for C20<age≤C40; 50 points for C40<age≤C60; 25 points for C60<age≤C80; and 0 points for utilities with age>C80 (i.e., 80 years).

Pipe material

Four types of pipe material have been identified in studied utilities (see Appendix F). According to Villeneuve et al. (1998), grey iron pipes are excessively corrodible, and are being abandoned for that reason. So no performance points had been allotted for grey iron percent of utility pipe material, nor for other pipe material percent (negligible). Only ductile iron and PVC pipe percents (i.e., the sum of the percents of these materials for each utility) have been converted into performance points. Since the possible maximum of pipe material percent is 100, this number has been taken as reference value. If the sum of ductile iron and PVC percents is =C60, the concerned utilities received 50 points; 75 points for C60<pipe material percent≤C80; and 100 points for pipe material percent >C80. No utility had percent less than C60 (that is, 60 %).

Pipe breakage

According to McDonald et al. 1997, a main break rate can be considered abnormally high when it exceeds 40/100km/year. None of studied utilities recorded as many breaks. However, that value has been taken as indication (as maximum or C100) for comparison purposes. If utility’s annual pipe breakage rate ≤C20, 100 points were allotted; 75 points for C20<pipe breakage rate≤C40; 50 points for C40<pipe breakage rate≤C60; 25 points for C60<pipe breakage rate≤C80; and 0 points for annual pipe breakage rate >C80. Note that C20, C40, C60, and C80 equalled 8, 16, 24, and 32breaks/100km/year, respectively.

System flushing

In the conditions of the province of Quebec (Canada), it is a sign of good management routine (or practice) to perform at least two flushings of the drinking water distribution network each year, with the first coming in early Spring (i.e., generally by April) and the second in late Autumn (by October). Many utilities perform more than two flushings per year. Thus, utilities that did only 1 flushing per year received performance 50 points on that variable; and 100 points for 2 flushings or more. All utilities did at least one flushing each year.

Table G.1. Explanations as to how the parameter values were converted into performance scores (continued-4)

Variables

Performance points attribution details

Tap water residual chlorine

The maximum average residual chlorine concentration in any one of the studied distribution systems (i.e., utilities) was about 0.8 mg/L (see Appendix C). This value represents the average for water samples taken at three sampling points (that are, chlorination facility, central part of distribution system, and distribution system extremity). To allow for relative performance comparisons, the 0.8 mg/L value has been considered as equalling C100. Thus, for average tap water residual chlorine ≤C20, 0 points were allotted; 25 points for C20< tap water residual chlorine ≤C40; 50 points for C40< tap water residual chlorine ≤C60; 75 points for C60< tap water residual chlorine ≤C80; and 100 points for tap water residual chlorine >C80. Note that C20, C40, C60, and C80 equalled 0.16, 0.32, 0.48, and 0.64 mg/L, respectively.

Tap water HPC bacteria

The maximum average HPC bacteria counts in any one of the studied distribution systems (i.e., utilities) was about 140 cfu/mL (see Appendix C). This value represents the average for water samples taken at three sampling points (that are, chlorination facility, central part of distribution system, and distribution system extremity). To allow for relative performance comparisons, that value has been considered as equalling C100 (note that the 2001 QDWR gave a threshold of 500 cfu/mL for HPC bacteria water samples to be taken at distribution system extremity). Thus, for average tap water HPC bacteria counts ≤C20, 100 points were allotted; 75 points for C20< tap water HPC bacteria counts ≤C40; 50 points for C40< tap water HPC bacteria counts ≤C60; 25 points for C60< tap water HPC bacteria counts ≤C80; and 0 points for average tap water HPC bacteria counts >C80. Note that C20, C40, C60, and C80 equalled 28, 56, 84, and 112 cfu/mL, respectively.

Tap water atypical bacteria

The maximum average atypical bacteria counts in any one of the studied distribution systems (i.e., utilities) was about 30 cfu/100mL (see Appendix C). This value represents the average for water samples taken at three sampling points (that are, chlorination facility, central part of distribution system, and distribution system extremity). To allow for relative performance comparisons, that value has been considered as equalling C100 (note that the 2001 QDWR gave a threshold of 200 cfu/100mL for atypical bacteria in distributed water). Thus, for average tap water atypical bacteria counts ≤C20, 100 points were allotted; 75 points for C20< tap water atypical bacteria counts ≤C40; 50 points for C40< tap water atypical bacteria counts ≤C60; 25 points for C60< tap water atypical bacteria counts ≤C80; and 0 points for average tap water atypical bacteria counts >C80. Note that C20, C40, C60, and C80 equalled 6, 12, 18, and 24 cfu/100mL, respectively.