Too Pure Water from Orange County Water District Results in Pipeline Rehabilitation Project

The Orange County Water District Groundwater Replenishment System treats secondary effluent from Orange County Sanitation District’s wastewater treatment plant in California through microfiltration, reverse osmosis, and advanced oxidation for groundwater recharge. The facility produces 100 million gallons per day of purified water. Since 2008, the water from the facility has been conveyed to recharge facilities via a cement mortar lined steel pipeline. Inspections have revealed deterioration of the lining. The highly purified water has low mineral content and tends to corrode cementitious material. Lime is added to reduce corrosiveness, but the targeted alkalinity has not always been achieved. Improvements have been made to stabilize the GWRS product water however, degradation has continued, and rehabilitation technologies were explored. In September 2018, F.D. Thomas, Inc., applied epoxy to 20,000 linear feet of 78-in. pipeline. Since completion of the project, solids loading in the water has shown a 75% decrease, indicating that the epoxy has prevented the lining from deteriorating further. In April 2020, an inspection of the epoxy will be performed.