4.4 SR 04-19-2021 - Laserfiche WebLink

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City of Elk River Design Standards A. Flushing: After the applicable retention period, heavily chlorinated water shall not remain in prolonged contact with the pipe. Chlorinated water shall be flushed from the main until chlorine concentration is no higher than generally in the system for domestic use. The environment to which the chlorinated water is to be discharged shall be inspected. The Contractor shall be responsible to ensure that the receiving area is not damaged by the chlorinated water and shall use a reducing agent for neutralization when necessary. B. Bacteriological Tests: After final flushing and before the watermain is placed in service, samples of water shall be collected from the end of the main and each branch line for testing for bacteriological quality in accordance with Standard Methods for the Examination of Water and Wastewater, and shall show the absence of coliform organisms. Samples shall be at a rate of one per every 1000 feet of pipe. One sample shall be taken a minimum of 24 hours after flushing. A higher rate of sampling may be required to include all branch line. If water in the pipe does not meet the Minnesota Department of Health requirements, disinfection procedure shall be repeated until meeting the requirements. The pulling of all samples shall be witnessed by a representative of Elk River Municipal Utilities. Electrical Conductivity Tests A conductivity test within one week after completion of pressure testing of the watermain on all ductile iron pipe watermain will be required. On watermain reconstruction projects, the Contractor shall perform the conductivity test prior to service line reconnections to ensure main line isolation from house services. The system (pipeline, valves, fittings and hydrants) shall be tested for electrical continuity and current capacity. The electrical test shall be made after the hydrostatic pressure test and while the line is at normal operating pressure. Backfilling shall have been completed. The line may be tested in sections of convenient length as approved by ERMU. Direct current of 350 amperes plus or minus 10%, shall be passed through the pipeline for 5 minutes. Current flow through the pipe shall be measured continuously on a suitable ammeter and shall remain steady without interruption or fluctuation throughout the 5-minute test period. Insufficient current or intermittent current or arcing, indicated by large fluctuation of the ammeter needle, shall be evidence of defective contact in the pipeline. The cause shall be isolated and corrected. Thereafter, the section in which the defective test occurred shall be retested as a unit and shall meet the requirements. Sources of D.C. for these tests may be motor generators, arc welding machines, or other approved sources. All such equipment shall be furnished by the Contractor. Cables from the power source to the section of system under test should be of sufficient size to carry the test current without overheating or excessive voltage drop. Electrical conductivity testing shall not be performed on plastic or HDPE watermain. Tracer (location) testing of all watermain shall be completed after all service installations have been completed. END OF SECTION 3400 © City of Elk River, Minnesota — All rights reserved 18