1. (a) Dechlorination to reduce free and combined chlorine residuals in WWTP effluent, if required by permit, shall be by use of sulfite salt solutions.

2. (b) Dechlorination systems shall:

   1. (1) Be sized to chemically neutralize 5 parts per million total residual chlorine at all flows;
   2. (2) Be of the positive displacement type;
   3. (3) Include storage of sufficient volume to provide for dosing at the anticipated maximum dose rate at design annual average flow for 15 days;
   4. (4) Include a redundant dechlorination feed pump;
   5. (5) Provide thorough hydraulic or mechanical mixing at the point of sulfite injection;
   6. (6) Provide a flow proportional feed forward control system;
   7. (7) Provide a sampling point for compliance monitoring after dechlorination;
   8. (8) Provide an alarm system to actuate upon failure of the dechlorination feed system;
   9. (9) Have chemical storage tanks equipped with a mechanical mixing device to keep the chemical solution completely mixed; and
   10. (10) Have dechlorination solutions, storage tanks, pumps, and feed lines protected from freezing.

Source. (See Revision Note at chapter heading for Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14; ss by #14258, eff 7-1-25, EXPIRES: 7-1-35