Section 327IAC8-2.6-6. Filter backwash

   All subpart H systems that employ conventional filtration or direct filtration treatment and recycle spent filter backwash water, thickener supernatant, or liquids from dewatering processes shall meet the following requirements:

(1) A system shall notify the commissioner in writing by December 8, 2003, if the system recycles spent filter backwash water, thickener supernatant, or liquids from dewatering processes. This notification shall include, at a minimum, the following information:

(A) A plant schematic showing the following:

(i) The origin of all flows that are recycled, including, but not limited to, spent filter backwash water, thickener supernatant, and liquids from dewatering processes.

(ii) The hydraulic conveyance used to transport all flows that are recycled, including spent filter backwash water, thickener supernatant, and liquids from dewatering processes.

(iii) The location where all flows that are recycled, including spent filter backwash water, thickener supernatant, and liquids from dewatering processes, are reintroduced back into the treatment plant.

(B) Typical recycle flow in gallons per minute.

(C) The highest observed plant flow experienced in the previous year in gallons per minute.

(D) Design flow for the treatment plant in gallons per minute.

(E) Commissioner-approved operating capacity for the plant where the commissioner has made such determinations.

(2) Any system that recycles spent filter backwash water, thickener supernatant, or liquids from dewatering processes shall return these flows:

(A) through the processes of a system's existing conventional or direct filtration system as defined in 327 IAC 8-2-1(14) and 327 IAC 8-2-1(18); or

(B) at an alternate location approved by the commissioner by June 8, 2004.

If capital improvements are required to modify the recycle location to meet the requirement in this subdivision, all capital improvements shall be completed no later than June 8, 2006.

(3) Subpart H systems shall collect and retain on file the following recycle flow information on forms provided by the department for review and evaluation by the commissioner beginning June 8, 2004:

(A) A copy of the recycle notification and information submitted to the commissioner under subdivision (1)(B) through (1)(E).

(B) A list of all recycle flows and the frequency with which they are returned.

(C) The average and maximum:

(i) backwash flow rate through the filters; and

(ii) duration of the filter backwash process in minutes.

(D) The typical filter run length and a written summary of how the filter run length is determined.

(E) The type of treatment provided for the recycle flow.

(F) Data on the following:

(i) The physical dimensions of the equalization and treatment units.

(ii) The typical and maximum hydraulic loading rates.

(iii) The type of treatment chemicals used and average dose and frequency of use.

(iv) The frequency at which solids are removed, if applicable.

(Water Pollution Control Division; 327 IAC 8-2.6-6; filed May 1, 2003, 12:00 p.m.: 26 IR 2859; filed Oct 24, 2006, 3:03 p.m.: 20061122-IR-327050255FRA)