Ala. Admin. Code r. 335-7-6-.09

Current through Register Vol. 42, No. 12, September 30, 2024

Section 335-7-6-.09 - High Rate Filtration Requirements

Filtration rates for conventional filters greater than two gpm per square foot of filter area require a permit modification. For high rate filtration approval, the following requirements must be met prior to the system requesting a permit modification:

(a) The duration of the High Rate Study must be a minimum of 30 consecutive days and during a time when raw water turbidity is historically at its highest. The plant must be operated 24 hours per day for the duration of the study.

(b) All treatment units must be utilized for the entire duration of the High Rate Study and operated at the proposed capacity. Any deviation from this requirement requires Departmental approval.

(c) The coagulation process shall be controlled either by zeta potential, streaming current detector or other approved methods.

(d) Indicating and recording turbidity monitors shall be provided for monitoring the turbidity of:

1. Raw water;

2. Clarified water prior to filtration at representative points;

3. Filter effluent from each filter.

(e) pH monitoring equipment shall be provided for monitoring

1. Raw water;

2. Treated water;

3. Finished water.

(f) Chlorine residual indicating and recording monitors shall monitor the finished water leaving the plant.

(g) Filtration rates shall not exceed eight gallons per minute per square foot of filter area.

(h) Filters shall be of the dual media or multimedia type.

(i) The plant shall meet the following parameters for a 12-month period prior to applying for approval to conduct a high rate study and applying for an increase in the filtration rate.

1. The treatment facility shall meet the Area Wide Optimization Program goals as set forth in the latest revision of EPA's handbook: Optimizing Water Treatment Plant Performance Using the Composite Correction Program or as specified by the Department.

2. The water system shall not have exceeded any primary or secondary water quality standards within the past 12-month period.

3. The water system shall have no outstanding violations or major system deficiencies.

(j) The minimum detention time for the settling basins must be two hours with sludge removal and four hours without sludge removal. Basins equipped with tube settlers or plate settlers and continuous sludge removal do not have to meet the detention time requirement, but the flow rate through the tube or plate settlers can not exceed the manufacturer's maximum recommended flow rate. A demonstration of the actual settling basin detention times must be completed along with the high rate filtration study.

(k) The detention times for the flash mix and flocculator basins will be waived.

(l) Water Treatment plants requesting high rate approval after December 31, 2005 must have a minimum of two treatment trains. These trains must be capable of independent operation from flocculation through filtration.

(m) Systems operating at filtration rates above four gpm/sf must meet the following additional requirements:

1. System must have 24 hour per day access to bacteriological analysis capabilities.

2. An annual evaluation of the raw water source shall be performed. This must include fecal coliform monitoring and an inventory of all discharges and activities which may impact the raw water quality available to the plant.

3. The system must analyze one sample per day from the water treatment plant's effluent for the presence of coliform and E-coli if any result is coliform positive. Any positive sample must be reported to the Department within 24 hours. The Department may increase the system's monthly bacteriological sampling requirements due to any positive result.

(n) Upon completion of the High Rate Study a report must be submitted to the Department for approval.

(o) Approval to operate at an increased filtration rate above two gpm per square foot of filter area can be revoked if any of the above conditions are not met or if the water system receives an unsatisfactory score on a Sanitary Survey Report.

Ala. Admin. Code r. 335-7-6-.09

May 23, 1977. Repealed and Readopted: January 4, 1989; October 31, 1990; effective December 5, 1990. (Rule was renumbered from .07 to .15, as per certification filed December 21, 1998; effective January 25, 1999, with no changes made to the rule.) Repealed and New Rule: Filed November 7, 2005; effective December 12, 2005. Amended: Filed December 18, 2007; effective January 22, 2008. Amended: Filed April 21, 2009; effective May 26, 2009.

Authors: Edgar K. Hughes, Dennis D. Harrison

Statutory Authority:Code of Ala. 1975, §§ 22-23-33, 22-23-49, 22-22A-5, 22-22A-6.