533-1A August 2018

Superseding

MOC-533-1

AUGUST 1991

STANDARD SPECIFICATION

POTABLE WATER TANK and SYSTEM DISINFECTION

1. SCOPE

1.1 This specification contains the general requirements for disinfecting the potable water tanks and system on NOAA ships.

2. REFERENCES

2.1 “Vessel Sanitation Program, 2011 Construction Guidelines, U.S. Department of Health and Human Services, section 22.10, Disinfection of the Potable Water System”.

3. DEFINITIONS

3.1 Free Available Chlorine (FAC) - Concentration of residual chlorine in water present as dissolved gas (Cl2), hypochlorous acid (HClO), and/or hypochorite ion (CIO-). A test kit which measures free chlorine will indicate the combined concentrations of HCLO, ClO-, and Cl2.

4. REQUIREMENTS

4.1 Potable Water Tank Disinfection

4.1.1 General Requirements

a. Isolate the potable water tanks to be disinfected from the rest of the potable water service system. Thoroughly rinse and drain each tank’s interior.

b. The chlorine solution used to disinfect the tank must be diluted and added through a sounding tube or threaded connection. Immediately after adding the chlorine solution, rinse the sounding tube or threaded connection with at least five gallons of potable water.

4.1.2 Disinfection Procedure

a. Fill the tank with potable water until it starts to overflow, then stop. Exercise care not to pressurize the tank. As the tank fills, add chlorine solution to achieve at least 100 parts per million (ppm) Free Available Chlorine (FAC) content in the completely filled tank.

b. Monitor the FAC content hourly for at least four hours. If the FAC content drops below 50 ppm at any time, add additional chlorine solution to raise the FAC content back to 100 ppm and restart the four hour monitoring period. Continue monitoring and raising the FAC content until the FAC content remains at or above 50 ppm for a four hour period.

c. If disinfecting more than one tank, repeat the above procedure for each tank. At the contractor’s discretion, the same water may be used to disinfect each consecutive tank, as long as the initial FAC content is increased to 100 ppm at the start of the four-hour monitoring period.

d. Drain each tank and refill with potable water. Repeat the above disinfection procedure, except start with an initial FAC content of at 1.0 ppm or greater and monitor the FAC content for 30 minutes. Continue monitoring and raising the FAC content until the FAC content remains at or above

0.2 ppm for a 30 minute period.

e. Drain each tank and refill with potable water until the total FAC content falls below 1.0 ppm.

4.2 Potable Water System Disinfection

4.2.1 Disinfect the entire Potable Water System, including the potable water tanks, in accordance with reference 2.1 and the potable water tank disinfection requirements in 4.1 above.

4.2.2 Monitor the FAC at various plumbing fixtures on each deck throughout the vessel (forward, aft, port, and starboard) to ensure that the 50 ppm free residual chlorine has circulated throughout the distribution system to include the distant sampling points.

4.2.3 After completion of the disinfection process, take additional samples at the same distant plumbing fixtures to validate that the FAC levels at these points are below 1.0 ppm.

4.2.4 Within 24 hours, submit a written Condition Report to the Contracting Officer’s Representative (COR) with the sample locations and FAC readings.

APPENDIX A

The following checklists are for guidance only. The Contractor is required to meet all requirements in the specification, whether or not they are captured accurately or fully in the checklists.

Potable Water Tank Disinfection Checklist

Check Delivery Period Action Service 1 Prior Tank Disinfection Perform Isolate the Potable Water Tank (s) from the rest of the system.

2 Prior Tank Disinfection Perform Rinse and drain the Potable Water Tank(s) interiors.

3 Tank Disinfection Perform Fill tank with potable water until it starts to overflow.

Do not pressurize tank.

4 Tank Disinfection Perform Add diluted chlorine solution to tank through a sounding tube or threaded connection until FAC is above 100 ppm.

5 Tank Disinfection Perform Rinse sounding tube or threaded connection with at least 5 gallons of fresh potable water.

6 Tank Disinfection Monitor Each hour, measure the FAC. If the FAC drops below 50 ppm, add additional chlorine solution until it is above 100ppm, and rinse the sounding tube or threaded connection. Continue this process until the FAC stays above 50 ppm for four consecutive hours.

7 Tank Disinfection, if more than one tank

Perform Repeat steps 3 – 6 for each tank.

8 Tank Disinfection Perform Drain each tank and fill with potable water until the FAC falls below 1.0 ppm.

Potable Water System Disinfection Checklist 1 System Disinfection Perform Clean, Disinfect, and Flush potable water tanks and potable water system using potable water with 50 ppm FAC for a minimum of 4 hours.

2 System Disinfection Monitor Monitor various plumbing fixtures on each deck throughout the vessel (forward, aft, port, and starboard) to ensure that the 50 ppm FAC has circulated throughout the distribution system to include distant sampling points.

3 System Disinfection Perform Flush the tanks and system with potable water until the FAC drops below 1.0 ppm.

4 System Disinfection Monitor Monitor various plumbing fixtures on each deck throughout the vessel (forward, aft, port, and starboard) to ensure that the FAC is below 1.0 ppm throughout the distribution system to include distant sampling points.

5 System Disinfection Submit Submit to the COR a Condition Report that includes the sampling locations and FAC measurements taken in steps 2 and 4.