NEW RULE I ULTRAVIOLET TREATMENT FOR GROUNDWATER SOURCES  (1)  Systems that use ultraviolet (UV) treatment for any groundwater source must meet the requirements of this rule All UV treatment must be reviewed and approved by the department under the requirements of ARM 17.38.101.  All systems that are designed and approved to provide 4-log virus inactivation must treat all water to be served to achieve 4-log virus inactivation.  

(2) For systems using UV treatment that does not provide 4-log virus inactivation: 

(a) a sample tap must be installed that allows for sampling of raw water from each source individually;

(b) one raw water total coliform sample must be collected by the system from each source that is subject to the UV treatment at the same frequency as the distribution system total coliform samples.  Raw water samples under this rule are in addition to routine total coliform monitoring; and

(c) raw water sample results are subject to ARM 17.38.211, 17.38.215, and 17.38.234.

(3) Systems with UV treatment that provide 4-log virus inactivation must monitor to ensure the UV treatment is functioning.

(a)  Monitoring must be done at the point of disinfectant application.

(b)  The dose and flow rate must be monitored and recorded continuously.

(c)  For each day the treatment system is operating and serving water, the following must be recorded for each UV reactor:

(i)  date;

(ii)  treatment plant name;

(iii)  treatment plant on and off time;

(iv)  dose; and

(v)  flow rate.

(4) Systems with UV treatment that provide 4-log virus inactivation must report on department-approved forms and formats that include the following information:

(a) Public water system name; public water system identification number; month and year; treatment plant name; treatment plant status (on and off);

(b) For each day the treatment system was operational and serving water, it must include the date, minimum daily dose, and highest flow rate;  

(c) If the UV treatment system consists of multiple UV reactors, the monitoring and reporting shall be for each reactor separately;

(d) The operational status of all UV lamps; and

(e)  The calibration of ultraviolet transmittance (UVT) instruments, calibration of the UV sensors, and recalibration of reference sensors in accordance with a protocol the department approves.

(f)  Water that does not meet the specifications of this rule is not allowed.  All of the water served must be treated by UV treatment to the minimum UV dose as approved by the department.

REASON: In NEW RULE I, the department proposes requirements for public water supply systems that use ultraviolet (UV) treatment for groundwater sources.  Such requirements already exist for surface water sources.  With advances in UV technology, the decreasing cost of units, and the scaling of the application to smaller systems, the technology is now being used for more groundwater sources.  The proposed new rule is necessary to protect public health by ensuring that groundwater UV treatment units reach the disinfection levels that they are intended to reach.

The proposed new rule sets forth requirements for systems that have installed UV treatment but are not required to meet 4-log virus inactivation, and for those that are required to meet 4-log virus inactivation.

For those systems that do not provide 4-log virus inactivation, the proposed new rule requires the system to collect raw water samples from each source. This is necessary because UV treatment that provides less than 4-log virus inactivation may prevent the indicator organism (total coliform) from reproducing without having an effect on viruses. By inactivating the indicator organism, but not the pathogens in the water, a negative total coliform sample may not accurately reflect the contamination level of the water being served. The proposed requirements in (2)(a), that a sample tap be installed to sample for raw water, and in (2)(b), that raw water be sampled at the same frequency as total coliform, are necessary to ensure that risks of contamination are identified.  The requirement in (2)(c), that raw water samples be subject to the federal Groundwater Rule and revised total coliform rules as outlined in ARM 17.38.211, 17.38.215, and 17.38.234, is necessary because these rules provide specific requirements to address positive total coliform sample results that are indicative of a water quality problem.  It is not intended that consecutive systems (e.g., vending machines, etc.) be subject to this rule because consecutive systems, by definition under 40 CFR 141.2, receive finished water.

For those systems that do have to meet 4-log inactivation, the department proposes the monitoring requirements in (3) and reporting requirements in (4). 

Section (3) proposes UV treatment monitoring requirements.  Systems must monitor at a higher frequency than is required to report to the department in order to establish the lowest values for the day.  In (3), the proposed UV treatment monitoring for groundwater sources mirrors the surface water treatment rule's UV requirements.  In (3)(a), the monitoring must occur at the application site because that is where the treatment occurs, and there is no residual.  The treatment is immediate, and the monitoring is only accurate at the point of disinfectant application.  In (3)(b), the proposed rule requires the dose and flow rate to be measured continuously because without measuring it continuously, it will be unknown if water that does not meet the specifications of this rule is served.  Each day that the UV treatment is operational and serving water, systems need to record the date, treatment plant name, treatment plant on and off time, and, for each UV reactor, the dose and flow rate as described in (3)(c).  The dose is calculated from several parameters, so the reactor must monitor the components to calculate the dose. 

Section (4) proposes reporting requirements that must be submitted to the department about UV treatment.  This requirement is a necessary part of the monitoring process because if the minimum daily dose is above the designed and approved dose, the department confirms that the water is being treated to 4-log virus inactivation standards.

Subsection (4)(c) requires systems that have multiple UV reactors to report the monitoring requirements separately.  This is especially necessary for UV treatment systems that have multiple UV reactors in a series to achieve 4-log virus inactivation (e.g., a 2-log reactor followed by another 2-log reactor).  The department needs to know that each reactor met its approved dose to be able to determine if the UV treatment system met the 4-log virus inactivation standard together.

Subsection (4)(d) requires information about the UV treatment lamps.  The lamps are part of the apparatus that sends the UV light through the water.  Knowing which lamps are in operation will be helpful to troubleshoot problems with the treatment.

In (4)(e), the proposed rule requires that the UVT (ultraviolet transmittance) instruments, the UV sensors, and the reference sensor units be calibrated and reported according to state-established protocols as authorized by 40 CFR 141.403(b)(3)(iii) for groundwater, which is consistent with the surface water treatment rule, as authorized by 40 CFR 141.720(d)(3) and 40 CFR 141.403(b)(3)(iii) authorizes the department to require monitoring of alternative treatment (e.g., UV) and to determine subsequent monitoring and reporting requirements.

Subsection (4)(f) proposes that the reported minimum daily dose must be equal to or greater than the approved dose.  This is how the department will verify compliance with UV treatment reporting. If a water system reports a minimum daily dose that is below the approved UV dose, then the water system served any water that did not meet the 4-log virus inactivation standard and would be in violation.  This standard differs from the UV treatment rule for surface water that only requires 95% of the water must meet the approved UV dose.  Groundwater sources either confirmed to be an E.coli-positive source, or that is susceptible to pathogen contamination based on environmental factors (e.g., shallow static water level, proximity to waste water infrastructure, etc.) are required to treat to 4-log virus inactivation. All water (100%) must be treated to the 4-log virus inactivation standard because the UV treatment is a form of disinfection that does not maintain a residual or continual treatment after point of application.  If some of the water served is not treated, then it is possible for pathogens to be supplied to the distribution system for consumption.  All water served must be treated to the 4-log virus inactivation standard to ensure that all the served water is pathogen free.

NEW RULE I will be applied to public water systems with groundwater sources that have new UV treatment.  However, there are public water systems that voluntarily installed UV treatment that were not reviewed and approved by the department, and these systems may develop problems.  If a system with existing voluntary UV treatment develops a problem (e.g., positive total coliform or E. coli sample results from source or distribution system, etc.) that makes the department question the microbial quality of the water served, the system will be subject to these rules to protect public health.

17.36.126 ADOPTION BY REFERENCE (1) For purposes of this chapter, the department adopts and incorporates by reference the following documents.  All references to these documents in this chapter refer to the edition set out below:

REASON: It is reasonable and necessary to amend this rule to update the year to reflect the current Circular DEQ-1 edition.

(22) For purposes of this chapter, the department adopts and incorporates by reference the following documents.  All references to these documents in this chapter refer to the edition set out below:

(a) Department Circular DEQ-1, 2022 2024 edition, which sets forth the requirements for the design and preparation of plans and specifications for public water supply systems;

REASON: It is reasonable and necessary to amend this rule to update the year to reflect the current Circular DEQ-1 edition.

REASON: It is reasonable and necessary to amend this rule to require the water system to record, keep, and submit the UV treatment-monitored information to the department. The department will use the submitted UV treatment-monitored information from the water systems to determine compliance with NEW RULE I. This is reasonable and necessary to protect public health by ensuring that the implemented UV treatment meets the design intent.

(16) For water sources not required to provide 4-log virus inactivation and use UV treatment that provides less than 4-log virus inactivation, a raw water sample tap must be installed on each and every source before all treatment (including blending of two or more sources).

D. to E. remain the same.

REASON: It is reasonable and necessary to amend Circular DEQ-1 to be consistent with proposed UV treatment for groundwater systems. For water sources that are not required to provide 4-log virus inactivation, a raw water sample tap is required. This is necessary to ensure better protection of public health, as discussed in the statement of reasonable necessity for NEW RULE I. Adding the monitoring and reporting requirements with rule citations helps the design engineers better understand the monitoring requirements to adjust the design for the intended operation of treatment systems accordingly.