Many Canadian cities are faced with the problem of an aging and deteriorating iron water distribution network - pipe breaks, leakage, and/or aesthetic water quality problems. Public confidence in municipalities’ ability to deliver safe, clean drinking water to customers has been eroded, especially in areas of water distribution networks receiving coloured water events that result from the internal corrosion of aging iron watermains. Cement mortar lining is one of the most widely used non-structural watermain rehabilitation methods for the prevention of coloured water events due to internal iron pipe corrosion; however, it is also thought/claimed to be a means of controlling corrosion pin-hole leakage. This thesis presents the results of a laboratory testing program designed to investigate the renewal of potable watermains via the use of cement mortar lining. The specific focus of this thesis is the ability of the cement mortar lining to bridge corrosion pin-holes and prevent water loss from the watermain, and the effects of mortar application on the corrosion protection provided to the iron watermain by cement mortar lining. The results of this study are based on short term testing and do not consider fatigue. The ability to bridge corrosion pin-holes / water loss prevention laboratory testing program found that pressure should not be returned to a newly lined watermain until the lining has cured for a period of at least four days to prevent failures from occurring prior to the lining achieving sufficient strength characteristics if the lining is to be used as a structural rehabilitation technique. The cure time corrected normalized thickness at failure data was found to be a Gumbel distributed data set. The Gumbel distribution can be used to predict the lining thickness required to bridge a known corrosion pin-hole diameter with a set degree of confidence that failure will not occur. A 3 mm thick cement mortar lining can bridge a pin-hole 12.0 mm in diameter while a 5mm thick cement mortar lining can bridge a pin-hole 19.9 mm in diameter with a 95% probability that failure will not occur Through the corrosion prevention testing program it was determined that the thickness of the cement mortar lining does not affect the ability of the lining to prevent corrosion from occurring. This was determined for cast iron pipes which have been lined for a period of one year. It is recommended that corrosion potential testing be performed on cement mortar lined watermains that have been in service for a longer period of time to determine if this consistent over the life cycle of the cement mortar lined watermain.

Many Canadian cities are faced with the problem of an aging and deteriorating iron water distribution network - pipe breaks, leakage, and/or aesthetic water quality problems. Public confidence in municipalities’ ability to deliver safe, clean drinking water to customers has been eroded, especially in areas of water distribution networks receiving coloured water events that result from the internal corrosion of aging iron watermains. Cement mortar lining is one of the most widely used non-structural watermain rehabilitation methods for the prevention of coloured water events due to internal iron pipe corrosion; however, it is also thought/claimed to be a means of controlling corrosion pin-hole leakage. This thesis presents the results of a laboratory testing program designed to investigate the renewal of potable watermains via the use of cement mortar lining. The specific focus of this thesis is the ability of the cement mortar lining to bridge corrosion pin-holes and prevent water loss from the watermain, and the effects of mortar application on the corrosion protection provided to the iron watermain by cement mortar lining. The results of this study are based on short term testing and do not consider fatigue. The ability to bridge corrosion pin-holes / water loss prevention laboratory testing program found that pressure should not be returned to a newly lined watermain until the lining has cured for a period of at least four days to prevent failures from occurring prior to the lining achieving sufficient strength characteristics if the lining is to be used as a structural rehabilitation technique. The cure time corrected normalized thickness at failure data was found to be a Gumbel distributed data set. The Gumbel distribution can be used to predict the lining thickness required to bridge a known corrosion pin-hole diameter with a set degree of confidence that failure will not occur. A 3 mm thick cement mortar lining can bridge a pin-hole 12.0 mm in diameter while a 5mm thick cement mortar lining can bridge a pin-hole 19.9 mm in diameter with a 95% probability that failure will not occur Through the corrosion prevention testing program it was determined that the thickness of the cement mortar lining does not affect the ability of the lining to prevent corrosion from occurring. This was determined for cast iron pipes which have been lined for a period of one year. It is recommended that corrosion potential testing be performed on cement mortar lined watermains that have been in service for a longer period of time to determine if this consistent over the life cycle of the cement mortar lined watermain.

For decades, cement mortar relining has been used successfully to extend the life of drinking water pipelines, although, few quantitative data exist on the short-term water quality impacts of this process. This study investigated mortar lining impacts on disinfectant by-product formation, alkalinity, metal leaching, pH and disinfectant consumption, and odor generation shortly after in-situ installation. The experimental design used a 30-day, coupon immersion procedure that simulated a relined 4-inch diameter pipe located in a low-flow system. Four water regimes were utilized; no disinfectant, chlorine (2 mg/L at pH 6 .5 and 8), and chloramines. Flavor Profile Analysis panels evaluated odors of samples and controls. Additionally, the affects of three different phosphate-based corrosion prevention additive regimes were evaluated. Cement mortar leachates impacted water quality significantly during the first week of exposure. Alkalinity, hardness and pH increased dramatically after initial exposure, rising to approximately 600 mg/L as CaCO3 alkalinity, 770 mg/L as CaCO3 hardness, and pH 12 in the first two days. Sharp declines in alkalinity and hardness did not occur until after day 9 when the cement mortar was substantially cured and release of calcium hydroxide lessened. Chlorinated water residual disinfectant decay rate was increased substantially during the initial 24 hours and remained elevated until day 9. After day 1, there was not a significant increase in the formation of regulated haloacetic acids or trihalomethanes. Significant levels of aluminum (< 700 ug/L) and chromium (< 75 ug/L) were released at various times during the test period but their concentrations did not exceed USEPA water quality standards. Cement odor intensity levels were significantly higher than controls, persisted for 14 days, and were of an intensity that would be readily noticeable to consumers. The polyphosphate-based corrosion preventative resulted in less severe water quality effects than other phosphate additives or water without added phosphate. / Master of Science