25-REHABILITATION OF THE EAST ELEVATED STORAGE TANK

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2. Application - Spray the chlorine solution over the inner surface of the cleaned, empty structure using spraying equipment, or whitewash brushes. 3. Contact period - The chlorine solution should remain on the surface for AT LEAST 45 minutes. After that, the structure may be filled with potable water and allowed to set 18 hours. 4. Testing - After the contact and 18 hour setting period, a sample will be drawn, tested and upon reading of zero coliform will be turned back into service. B. Procedure 2- Adding Disinfectant to Water as Structure is Filled 1. Chlorine solution - Dissolve'/z lb. 70% calcium hypochlorite (HTH or Perchloron) as a paste in each 1,000 gallons of clean water needed to fill the structure to five percent of the total volume; or add 1 fluid ounce of 5% liquid bleach to each 8 gallons of clean water; or add 1 fluid ounces of 14 % liquid bleach to each 24 gallons of clean water. This gives a concentration of about 50 mg/1 available chlorine in the five percent of volume. For greatest effectiveness, add paste in batches as structure is being filled. 2. Contact period - Allow the chlorinated water to remain in the structure not less than 6 hours, add water to completely fill the tank and hold for 24 hours. 3. Test as in item A-4 above. C. Procedure 3- Adding disinfectant with a Portable Chlorinator as Water Enters the Structure. 1. Chlorine solution - Use chlorine solution sufficient to produce a concentration of 50 mg/1(see Procedure 2), available chlorine. If the flow rate of water is unknown and the dose cannot be computed, add chlorine solution until a water sample shows a dark red or brown color when a DPD chlorine residual test is run. Add to five percent as above in item 2. 2. Contact period - Allow chlorinated water to remain in the structure not less than 6 hours, then fill the tank as above and hold for 24 hours. 3. Test as in item A-4 above. Ts1o-2 454 L~