Title 18 . Environmental Conservation

Chapter 80 . Administrative Enforcement

Section 660. Monitoring requirements for systems avoiding filtration

18 AAC 80.660. Monitoring requirements for systems avoiding filtration

(a) In addition to the requirements of 18 AAC 80.655, the owner or operator of a Class A or Class B public water system that uses a surface water source and that does not provide filtration treatment shall meet the monitoring requirements of this section. However, if the department or EPA has determined in writing that filtration is required, the department will specify alternative monitoring requirements until filtration is in place.

(b) The owner or operator of a Class A or Class B public water system that uses a GWUDISW source shall meet the monitoring requirements of this section beginning six months after the department determines that the groundwater source is under the direct influence of surface water if the owner or operator

(1) does not provide filtration treatment as described in 18 AAC 80.650; and

(2) seeks to avoid filtration as described in 18 AAC 80.620.

(c) Fecal coliform or total coliform density measurements, as required by 18 AAC 80.620(b) (1), must be performed on representative source water samples immediately before the first or only point of disinfectant application. The owner or operator shall sample for fecal or total coliforms at the minimum frequency required in Table I of this subsection each week during which the system serves water to the public:

TABLE I. SAMPLING FREQUENCY FOR COLIFORM, FOR SYSTEMS WITHOUT OR AVOIDING FILTRATION.

System size (individuals served) Samples/week 500 or fewer 1 501 - 3,300 2* 3,301 - 10,000 3* 10,001 - 25,000 4* More than 25,000 5*

*Samples for systems serving over 500 individuals must be taken on separate days.

(d) One fecal or total coliform density measurement must be made each day that the system serves water to the public and that the turbidity of the source water exceeds one NTU unless the department finds, under (i) and (j) of this section, that the owner or operator, for logistical reasons outside the owner or operator's control, cannot have the sample analyzed within 30 hours after collection, or within 48 hours after collection for an area listed in 18 AAC 80.350(a) . The samples required under this subsection may be counted toward the weekly coliform sampling requirement of (c) of this section.

(e) Turbidity measurements required by 18 AAC 80.620(b) (2) must be performed on representative grab samples of source water immediately before the first or only point of disinfectant application at least every four hours when the system serves water to the public. The owner or operator may substitute continuous turbidity monitoring for grab sample monitoring if the owner or operator validates the continuous measurement for accuracy on a regular basis using a method specified in 18 AAC 80.665(e) .

(f) The total inactivation ratio for each day that the system is in operation must be determined

(1) under the following formula:

CT = (log inactivation) (5.057)(e a ) (e b )(e c )

where:

log inactivation can vary from 0.5 to 3;

e = natural logarithm, approximately 2.71828;

a = - 0.0693 x temperature (øC);

b = 0.361 x pH;

c = 0.113 x chlorine concentration in mg/l; or

(2) based on the CT 99.9 values in Tables J through R of this section, as appropriate.

(g) The parameters necessary to determine the total inactivation ratio under (f) of this section must be monitored as follows:

(1) the temperature of the disinfected water must be measured at least once each day at each residual disinfectant concentration sampling point;

(2) if the system uses chlorine, the pH of the disinfected water must be measured at least once each day at each chlorine residual disinfectant concentration sampling point;

(3) the residual disinfectant concentration ("C") of the water before or at the first customer must be measured each day during peak hourly flow;

(4) the disinfectant contact time ("T") must be determined for each day during peak hourly flow;

(5) if a system uses a disinfectant other than chlorine, the owner or operator shall demonstrate to the department, through standard sanitary engineering practices and principles, that CT99.9 values other than those specified in Tables Q and R of this section or other operational parameters are adequate to demonstrate that the system is achieving the minimum inactivation rates required by 18 AAC 80.640(a) (1).

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Notes to Tables J - R:

*These CT values achieve greater than 99.99 percent inactivation of viruses; CT values between the indicated pH values may be determined by linear interpolation; CT values between the indicated temperatures of different tables may be determined by linear interpolation; if no interpolation is used, the CT99.9 value at the lower temperature, and at the higher pH must be used.

**These CT values achieve greater than 99.9 percent inactivation of viruses; CT values between the indicated temperatures may be determined by linear interpolation; if linear interpolation is not used, the CT99.9 value at the lower temperature must be used for determining CT99.9 values between indicated temperatures.

***These CT values are for pH values of 6 to 9; these CT values may be assumed to achieve greater than 99.99 percent inactivation of viruses only if chlorine is added and mixed in the water before the addition of ammonia; if this condition is not met, the owner or operator shall demonstrate, based on on-site studies or other information, as approved by the department, that the system achieves at least 99.99 percent inactivation of viruses; CT values between the indicated temperatures may be determined by linear interpolation; if linear interpolation is not used, the CT99.9 value at the lower temperature must be used for determining CT99.9 values between indicated temperatures.

(h) The total inactivation ratio must be calculated as follows:

(1) if the system uses only one point of disinfectant application, the owner or operator may determine the total inactivation ratio based on either of the following two methods:

(A) one inactivation ratio, with the value CTcalc/CT99.9 is determined before or at the first customer during peak hourly flow; if the CTcalc/CT99.9 value is greater than or equal to 1.0, the 99.9 percent Giardia lamblia inactivation requirement has been achieved; or

(B) successive CTcalc/CT99.9 values, representing sequential inactivation ratios, are determined between the point of disinfectant application and a point before or at the first customer during peak hourly flow; under this subparagraph, the following method must be used to calculate the total inactivation ratio:

(i) the CTcalc/CT99.9 value must be determined for each sequence;

(ii) the CTcalc/CT99.9 values must be added together as represented by the formula S (CTcalc/CT99.9 );

(iii) if S (CTcalc/CT99.9 )ò 1.0, the 99.9 percent Giardia lamblia inactivation requirement has been achieved;

(2) if the system uses more than one point of disinfectant application before or at the first customer, the owner or operator shall determine the CT value of each disinfection sequence immediately before the next point of disinfectant application during peak hourly flow; the CTcalc/Ct99.9 value of each sequence and S (CTcalc/CT99.9 ) must be calculated using the method described in (1)(B) of this subsection to determine if the system is in compliance with 18 AAC 80.635 and 18 AAC 80.640;

(3) in the alternative, the total percent inactivation for a system with one or more points of residual disinfectant concentration monitoring may be calculated by solving the following equation; if the system applies disinfectants at more than one point before or at the first customer, the owner or operator must determine the CT value of each disinfectant sequence before or at the first customer:

Total percent inactivation = 100 - (100/10 z )

Where z = 3 x S (CTcalc/CT99.9 ).

(i) The department will not grant a waiver of the requirements of (d) of this section because of a lack of sampling containers. The department will consider the following situations to be logistical problems allowing a public water system to qualify for a waiver from the requirements of (d) of this section:

(1) certified laboratories available to the system cannot analyze the samples within 30 hours after collection, or within 48 hours after collection for an area listed in 18 AAC 80.350(a) , because of limited days of operation or limited laboratory capacity;

(2) weather conditions make it impossible to ship the samples to the laboratory for analysis within 30 hours after collection, or within 48 hours after collection for an area listed in 18 AAC 80.350(a) ;

(3) shipping services from the system are limited so that samples cannot be collected, shipped, and analyzed within 30 hours, or within 48 hours for an area listed in 18 AAC 80.350(a) ; and

(4) other unusual or unpredictable situations, such as a landslide closing the road or knocking out a transmission line, make it impossible for the owner or operator to meet the 30-hour or 48-hour requirement.

(j) After the department finds that the owner or operator is unable to meet the 30-hour or the 48-hour sampling requirement because of a situation listed in (i) of this section, the department will grant a waiver of the requirements of (d) of this section. If the logistical problem is likely to persist, the department will grant a standing waiver that will remain in effect until the department rescinds or revises it. The department will keep a copy of the waiver in the department's file for the public water system until one year after the waiver expires or is rescinded or revised.

History: Eff. 10/1/99, Register 151; am 3/25/2001, Register 157

Authority: AS 46.03.020

AS 46.03.050

AS 46.03.070

AS 46.03.710

AS 46.03.720

Editor's note: Guidance on standard sanitary engineering practices and principles, as addressed in 18 AAC 80.660(g) (5), may be found in the department's Alaska Water Treatment Guidance Manual. Information about how to review or obtain this document is in the editor's note to 18 AAC 80.010.