1999-338A - Laserfiche WebLink

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i i downstream end of the section. At least one additional above -grade sampling tap shall be installed in each branch of a looped system at locations specified by the Engineer. Fire hydrants shall not be used as sampling points for bacteriological samples. C. The Contractor shall connect one end of the pipe system to a suitable potable water source and chlorine feed system and slowly fill the pipe with water while feeding chlorine at a continuous rate until the pipe system is full and a free residual chlorine of at least 200 mgll is obtained at each end and at intermediate sampling points as directed by the Engineer. During filling, each service and hydrant shall be cracked open and allowed to flow until chlorine is detected in the discharge. D, When the system is full and the required initial chlorine concentration is obtained, all outlet valves shall be closed and the chlorinated water retained for at least 24 hours, at which time the free residual chlorine shall be checked at the designated sampling points. If the free residual chlorine is less than 50 mg/1 at any point, the pipe system shall be reflushed and rechlorinated until the required 24 -hours residual chlorine is obtained, at which time the system shall be purged with potable water until residual ' chlorine is reduced to that of the water source. F. Suitable bacteriological samples shall then be taken at designated sampling points on 2 consecutive days and tested for total coliform by a laboratory certified by D.H.R.S. for microbiological analysis. Satisfactory results for coliform analysis shall be indicated by a total coliform count of less than I per 100 in 1. (MF) or less than 2.2 per 100 ml. (MPN, 5 tube, 10 ml.) for each sample. If any sample result is unsatisfactory, the disinfection and sampling procedure shall be repeated on part or all of the installed system, as directed by the Engineer, until all samples from 2 consecutive days show satisfactory results. Once the installed pipe system has been disinfected and bacteriological sampling begun, the system shall be kept continuously full with potable water under sufficient positive pressure to preclude contamination from outside sources, and shall be maintained in such condition until interconnection with the permanent water supply source is approved and completed. If, in the opinion of the Engineer, any part of the installation is subject to recontamination due to water loss from all or part of the installation, the cause shall be immediately corrected and the installation shall be redisinfected and retested to the extent directed by the Engineer. G. Highly chlorinated water used for disinfection shall be disposed of in a manner that will not cause a health hazard or damage to the aquatic environment of receiving waters. Unless otherwise directed by the Engineer, such water shall be dechlorinated with a satisfactory reducing agent or diluted to a maximum total residual chlorine concentration of 2 mgjl prior to discharging to surface waters, storm sewers, or sanitary sewers.