The city of Lawton, Oklahoma custom-built the Medicine Park Water Treatment Plant that utilizes modern equipment (considered “best available technology”) for water clarification and filtration. The treatment plant uses ozone as a pre-oxidant and chloramines as the primary disinfectant. Chlorine and ammonia are injected post filtration into a 30-inch ductile iron pipe that transports treated water into a concrete storage tank prior to distribution.
Less than 18 months after the Medicine Park Water Treatment Plant opened, operators began noticing higher than normal back pressure and shorter filter runs. While backwashing, operators observed that filters did not appear to be dirty, even though the loss of head telemetry indicated the need for cleaning. Telemetry calibration was checked and certified as operating correctly. Plant personnel began investigating further and discovered that the 30-inch effluent pipe, just past the chemical injection point for chlorine, was lined with heavy scale. Further investigation revealed that the 30-inch line had developed scale for approximately 130 linear feet past the injection point, and that the line had closed to a diameter of approximately 18 inches. Line replacement would be very difficult and expensive due to a section of the scaled pipe being installed under, and penetrating the floor of the concrete water storage tank.
Looking for a solution to remove heavy scale, the plant superintendent contacted Blue Earth Labs and inquired about its NSF 60 certified, advanced cleaning and infrastructure maintenance solutions. After discussion of the problem revealed the need for the plant to be operational as soon as possible, Blue Earth Labs determined that its Media Master® product could remove the scale from the line and enable the plant to be in operation within 48 to 72 hours.
Blue Earth Labs personnel arrived the next day and devised a method for introducing Media Master into the pipe by circulating water within the scaled section. After the proper dosage of chemical had been injected, the solution maintained contact with the scale overnight to dissolve and loosen the large deposits of scale.
The next morning, the solution within the pipe was pumped into the backwash recovery ponds for pH neutralization, and the pipe was reopened by removing the blind flange installed to hold the solution in the affected area of pipe. The volume of scale had not only been reduced significantly but almost all of the remaining scale had detached from the pipe and was lying in the bottom portion. Within a couple of hours, operators had removed the scale and began the process of coupling the pipe back together to reopen the plant.
Currently, the plant is back in service and operating within design parameters. The cost to replace the 130 linear feet of 30-inch ductile iron pipe was estimated at $220,000, due to a significant portion of the pipe being installed under and penetrating the floor of the water storage tank. The cost of chemically removing the scale was approximately $17,500. Thus, utilizing chemical cleaning solutions specifically engineered to remove deposits saved the city of Lawton nearly $202,500 while significantly reducing the labor and downtime needed to fix the scaling pipe.
The scaled effluent pipe was located under this water holding tank, making it near impossible to replace the scaled section of the pipe.
Media Master was injected into the scaled section of the pipe and left to react with the scale overnight.