1. (a) To determine compliance with the performance standards specified in section 64653 and the operating criteria in section 64660, a supplier shall conduct turbidity monitoring in accordance with table 64655. Monitoring shall be conducted when the treatment plant is in operation and pursuant to the operations plan required by section 64661.

   Table 64655

   Filtered Water Turbidity Monitoring

   If a supplier uses...

   Turbidity monitoring shall be conducted of...

   And the turbidity level shall be recorded...

2. (1) Conventional or direct filtration

3. (A) Each individual filter, continuously; and

   At least once every 15 minutes

   treatment and serves 10,000 or more persons

4. (B) The combined filter effluent^(b), continuously

   At least once every 15 minutes

5. (2) Conventional or direct filtration

6. (A) Each individual filter, continuously^(c); and

   At least once every 15 minutes

   treatment and serves fewer than 10,000 persons^(a)

7. (B) The combined filter effluent^(b), by grab sample at least once every four hours^(d)

   At least once every four hours

8. (3) Diatomaceous earth or slow sand filtration^(a)

   The combined filter effluent^(b), by grab sample at least once every four hours^(d)

   At least once every four hours

   _______________________________________________________

9. ^(a) A supplier using slow sand filtration, or serving 500 or fewer persons, that is in compliance with the performance standards specified in section 64653 may reduce turbidity monitoring of the combined filter effluent to one grab sample per day. The result shall be recorded daily.
10. ^(b) Representative sample prior to clearwell storage.
11. ^(c) If there are two or fewer filters, a supplier may conduct continuous monitoring of the combined filter effluent in lieu of continuous monitoring of each individual filter. The results shall be recorded at least once every 15 minutes.
12. ^(d) Continuous turbidity measurements may be substituted for grab sample monitoring provided the supplier validates the accuracy of the measurements on a weekly basis.
13. (b) A supplier shall calibrate turbidimeters used for continuous turbidity monitoring according to the procedure specified by the manufacturer.

14. (c) If there is an interruption in continuous turbidity monitoring due to equipment failure or maintenance, a supplier that uses conventional or direct filtration treatment shall conduct grab sample monitoring once every four hours in lieu of continuous monitoring until the continuous turbidimeter is back on-line. From the time of equipment failure or maintenance interruption, continuous monitoring shall be reinitiated:

    1. (1) For a supplier serving 10,000 or more persons, within 48 hours for the combined filter effluent and within five working days for the individual filter effluent; or
    2. (2) For a supplier serving fewer than 10,000 persons, within 14 working days for the individual filter effluent.

Note: Authority cited: Sections 116350, 116375, 131052 and 131200, Health and Safety Code. Reference: Sections 116350, 116375 and 116386, Health and Safety Code.

History

1. New section filed 5-6-91; operative 6-5-91 (Register 91, No. 25).

2. Amendment of subsection (b) and Note filed 6-8-98; operative 7-8-98 (Register 98, No. 24).

3. Amendment of section heading, section and Note filed 12-13-2007; operative 1-12-2008 (Register 2007, No. 50).

4. Amendment of section heading, section and Note filed 5-22-2013; operative 7-1-2013 (Register 2013, No. 21).

5. Editorial correction relocating article 3 heading to precede section 64654.8 (Register 2016, No. 19).