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Disinfection of Water Dist. Systems

Disinfection of Water Dist. Systems

(Section 02675)

PART 1 GENERAL

1.01 WORK INCLUDED

A. Contractor shall provide all materials, labor, equipment, transportation and other items required to perform disinfection of water distribution systems as required by applicable codes and regulations, and as specified herein.

B. Disinfection shall include but not be limited to the following:

     1. Flushing of water distribution system and supply lines

     2. Chlorine disinfection

     3. Final flushing

1.02 RELATED WORK

A. Section 02665 - Potable Water Distribution Systems

     1. Construction and installation of water distribution piping, hydrostatic testing, cleaning and flushing requirements.

1.03 REFERENCES

A. The applicable provisions of the latest editions of the References listed below shall govern the Work covered under this Section, unless there is a conflict between said References and the requirements of this Section. In the case of such a conflict, the requirements of this Section shall apply.

B. American Water Works Association (AWWA)

C. "Standard Methods for the Examination of Water and Wastewater", American Public Health Association, AWWA, and Water Pollution Control Federation

D. "State of Utah Public Drinking Water Regulations", State of Utah Department of Health, Division of Environmental Health

1.04 SUBMITTALS

A. Submit manufacturer's literature, certifications, and other product data in accordance with other sections and as specified herein.


B. Submittals required prior to testing include but are not limited to the following:

     1. Evidence of materials conformance with these specifications

     2. Proposed methods and equipment to be used for disinfection.

C. Submittals required after testing as a condition for final acceptance include but are not limited to the following:

     1. Results of chlorine residual tests.

     2. Results of bacteriologic quality tests.

1.05 QUALITY ASSURANCE

A. All disinfection and testing procedures shall be in accordance with applicable Federal, State, and local standards.

1.06 DELIVERY AND HANDLING

A. Contractor shall be responsible for proper transportation, unloading, handling, storage and security of all equipment and materials provided as part of this specification in accordance with manufacturer's recommendations.

B. Materials shall be stored in such a manner as to prevent damage or degradation. Any materials damaged or degraded prior to installation shall be removed from the project and replaced with new materials at no additional cost. Lost or stolen materials shall be replaced at no additional cost.

1.07 PROJECT CONDITIONS

Not Used

PART 2 PRODUCTS

2.01 MANUFACTURERS

A. Manufacturers providing materials as part of this specification shall have a minimum of five (5) years experience in the manufacture and testing of such materials.

B. Manufacturers shall provide, upon request, verification of a consistent record of meeting or exceeding materials or performance standards as specified herein.

2.02 CHLORINE

A. Tablets shall conform to AWWA B300 - Standard for Hypochlorites.

B. Liquid shall conform to AWWA B301 - Standard for Liquid Chlorine.

C. Store in a cool, dark, and dry environment to minimize deterioration.

PART 3 EXECUTION

3.01 EXAMINATION

A. Examine water facilities to verify they have been properly cleaned, flushed, and hydrostatically tested, as appropriate prior to performing disinfection Work. Verify that other Work will not contaminate or disturb disinfected facilities.

B. Notify Engineer and Owner at least 72 hours prior to any flushing and disinfecting.

3.02 METHODS AND PROCEDURES

A. General

     1. Disinfection procedures shall as a minimum be in accordance with the following specifications and regulations.

          a. AWWA C651 - Disinfecting Water Mains

          b. AWWA C652 - Disinfection of Water Storage Facilities

B. Preliminary Flushing of Water Distribution and Supply System

     1. The flushing velocity shall not be less than 2.5 feet per second.

     2. Water discharged from the flushing operation shall be conducted to approved natural drainage channels, storm sewers, or other locations in accordance with applicable laws, ordinances and regulations.

     3. No flushing water shall be discharged into a sanitary sewer.

C. Chlorination of Water Distribution and Supply System

     1. A 1 percent chlorine solution shall be prepared.

     2. The chlorine solution shall be applied to the water line with a gasoline or electrically powered chemical feed pump designed for feeding chlorine solutions. Feed lines shall be of such material and strength as to withstand safely the maximum pressures that may be created by the pumps. All connections shall be checked for tightness before the hypochlorite solution is applied to the main.


     3. Water from the existing distribution system or other approved sources of supply shall be made to flow at a constant, measured rate into the newly laid pipeline. The water shall receive a dose of the chlorine solution, also fed at a constant, measured rate. The two rates shall be proportioned so that the chlorine concentration in the water in the pipe is maintained at a minimum of 50 mg/l available chlorine.

     4. The ratio of application of the hypochlorite solution to water to maintain a 50 mg/l (50 ppm) chlorine concentration is as follows:

          a. Application Ratio: 1 gal. of 1 percent chlorine solution to 200 gal water.

     5. During the application of the chlorine, valves shall be manipulated to prevent the treatment dosage from flowing back into the line supplying the water.

     6. Chlorine application shall not cease until the entire line is filled with the chlorine solution.

     7. The chlorinated water shall be retained in the line for at least 24 hours, during which time all valves and hydrants in the section treated shall be operated in order to disinfect the appurtenances. At the end of this 24 hour period, the treated water shall contain no less than 25 mg/l chlorine throughout the length of the main.

D. Final Flushing of Water Distribution and Supply System

     1. After the applicable retention period, the chlorinated disinfection water shall be flushed from the line.

     2. Chlorine residual determination shall be made to ascertain that the heavily chlorinated water has been removed from the line. The line shall be flushed until the residual chlorine concentration is less than 1 mg/l.

E. Bacteriological Sampling and Testing

     1. Sampling and testing shall be conducted in accordance with AWWA Manual M12 - Simplified Procedures for Water Examination.

     2. Samples for bacteriologic analysis shall be collected in sterile bottles treated with sodium thiosulfate. No hose or fire hydrant shall be used in collection of samples. A sampling tap shall be as shown on the drawings.

     3. After final flushing, and before the water line is placed in service, a sample shall be collected from the water line at 1000 foot intervals, evenly spaced along the line, and tested for coliform organisms in accordance with the latest edition of "Standard Methods for the Examination of Water and Wastewater". The testing shall be by either the multiple tube fermentation technique or the membrane filter technique. Two samples shall be taken, from each location, at least 24 hours apart.

     4. All samples shall be taken from a sampling tap.

     5. If the initial disinfection fails to produce satisfactory samples, disinfection shall be repeated until satisfactory samples have been obtained.

     6. When the samples are satisfactory, the water line may be placed in service upon receiving notification from Midvale City to do so.

3.03 INSTALLATION

Not Applicable

3.04 PROTECTION

A. Contractor shall be responsible for maintaining disinfected facilities from contamination until acceptance by the Owner. Should facilities be contaminated prior to acceptance, Contractor shall re-disinfect and retest in accordance with 3.02 of these specification at no additional cost.

3.05 CLEANING

A. Refer to 3.02 of these specifications

3.06 TESTING

A. Refer to 3.02 of these specifications