16 Cross Country Water Main Replacement

Provide recommendations for cathodic protection based on field soil resistivity measurements Calculation Parameters: 1. The pipe will be installed in two sections a. The first section will be installed between Alexandria Pike and U.S. Route 27, a distance of approximately 520-ft b. The second section will be installed between Bob Huber Drive and the Claryville elevated water tank, a distance of approximately 1,540-ft c. The section of pipe between the west side of U.S. Route 27 and the east side of Bob Huber Drive (approximately 400-ft) is not being replaced. d. All tie-ins will be made to existing 12-inch water main. 2. The 2,500-ft of 16-inch polyethylene encased ductile iron pipe has an OD of 17.4-inch (DI specifications) 3. Majority of pipe will be installed to a minimum depth of 5.5-ft; approximately 700-ft of pipe will be installed to a minimum depth of 9.5-ft 4. The average soil resistivity in the Barnes Soil Layer Calculations for the 5.0-ft to 7.5-ft layer is 1,399-ohm-cm. The average soil resistivity in the Barnes Soil Layer Calculations for the 7.5-ft to 10.0-ft layer in the area of the deeper pipe location is 1,870-ohm-cm. 5. We ran two calculations using average soil resistivity readings of 1,400 ohm-cm and 1,870- ohm-cm. 6. The low soil resistivities indicate a very corrosive environment with respect to ductile iron pipe and an anticipated high current output of magnesium anodes, thus a reduced calculated design life. A 48-lb magnesium anode will provide the longest calculated life. 7. Zinc anodes were considered in the design, but they did not provide any longer calculated design life and there were only a few locations where the resistivities were under 1,000 ohmcm. 8. Consider only 2% of the pipe will be exposed to the surrounding environment due to tears of the polyethylene encasement during backfilling 9. Use 1.5 ma/sq-ft surface area current density for the exposed ductile iron pipe Engineers estimate is $1,239,599.90. Construction of approximately 2,080 linear feet of 16 class 50 ductile iron pipe water main together with the appurtenances and related work for a cross country water main from the water tower to old Alexandria Pike near Alexandria, Campbell County, Kentucky.

Division 33 -

Utilities, Instrumentation and Control for Utilities, Water Utilities, Water Utility Distribution Piping, Water Utility Distribution Equipment, Disinfecting of Water Utility Distribution, Water Utility Storage Tanks.