(A) General installation requirements. All water mains and services shall conform to the AWWA and APU standards for water mains and appurtenances. Bury depth will be a minimum of 84 inches not to exceed 120 inches.
(B) Hydrostatic testing and disinfection.
(1) The contractor shall be responsible for hydrostatic testing and disinfection of the water main and shall furnish, install, and bear the costs of all work, materials, and assistance required to complete these tests according to AWWA Standard for disinfecting water mains (ANSI/AWWA C651.92).
(2) Operation of all valves and hydrants will be done only by employees of the Public Utilities or other authorized agent. Under no circumstances shall the contractor or his employees open or close valves in the distribution system or operate fire hydrants connected to mains except when authorized. This provision applies both to the valves and hydrants on existing mains, and to newly installed valves and hydrants and mains at the time of and after they are opened to receive water from city mains.
(C) Hydrostatic (pressure) testing. After chlorine has been introduced into the main, a pressure and leakage test shall be conducted by the contractor under the supervision of the APU. The main shall remain isolated from adjacent mains and a gauge pressure of at least 150 psi shall be applied by pumping clean water containing 25 mg/l of chlorine. The duration of each pressure test shall be a minimum of two hours.
(D) Disinfection. Hypochlorite solution (calcium hypochlorite - HTH, sodium hypochlorite - bleach) shall be used of such strength to produce a concentration of 25 mg/l of chlorine in the main. The chlorinating agent shall be applied at the beginning within three feet of the valved section of the pipeline extension through a corporation cock inserted in the top of the new main. Water shall be supplied by Public Utilities personnel from the existing city water main so as to flow slowly at a constant rate into the newly installed water main. The chlorine shall be applied continuously at a constant rate to develop a column of chlorinated water that will expose all interior surfaces to a concentration of approximately 25 mg/l. Valves and hydrants shall be operated so as to disinfect appurtenances and pipe branches. Chlorine application shall not cease until the entire main is filled with chlorinated water. If at any time the application of chlorine is interrupted, the flow of water shall be stopped until chlorine application is resumed. After the main has been chlorinated, the solution shall remain in the main for at least 24 hours to assure disinfection. After the minimum 24 hours, the solution shall be tested at the extremities of the main and at intermediate points to make sure it has Residual chlorine strength of 10 mg/l.
(E) Flushing. After disinfecting the main, it shall be thoroughly flushed with city water at a fire hydrant or hydrants on the dead end or ends of the water main until the water in the main has approximately the same chlorine residual as water in the existing mains. This shall be done by personnel of the Public Utilities or authorized personnel. Flushing stations shall be placed as shown on the plans or as directed by the Public Utilities.
(F) Bacteriological tests. Two consecutive bacterial tests must be negative for the presence of coliform. Tests must be analyzed by an approved Minnesota Department of Health Lab. When all tests on the water main have been successfully completed, and a copy of the results have been submitted to the Public Utilities, the main shall be placed in service by the Public Utilities and no further work on the main or its valves will be permitted without permission.
(Ord. 315, passed 3-22-2017)