12 Va. Admin. Code § 5-590-421 - Groundwater system treatment techniques

A. The owner of a groundwater system that (i) has a confirmed E. coli contamination as described in 12VAC5-590-379 B or (ii) has been notified in writing of a significant deficiency as described in 12VAC5-590-350 D shall meet the requirements of this section. Failure to meet any requirement of this section after the applicable time period specified is a treatment technique violation.

1. The owner shall implement one or more of the following corrective actions:

a. Correct all significant deficiencies;

b. Provide an alternate source of water;

c. Eliminate the source of contamination; or

d. Provide treatment of the groundwater source that reliably achieves at least 4-log treatment of viruses before or at the first customer.

2. Unless the department directs the owner to implement a specific corrective action, the owner shall consult with the department regarding the appropriate corrective action within 30 days of receiving written notification from the department or the laboratory. This consultation may take the form of a telephone conversation, email, meeting, or other mechanism agreed to by the department.

3. Within 45 days of receiving this notification, the owner shall submit a written corrective action plan (CAP) to the department that satisfactorily addresses the deficiency. The CAP shall include a schedule for completing individual actions, and it shall include one or more of the corrective actions in subdivision A 1 of this section. Approval of the CAP by the department constitutes an approved CAP.

4. Within 120 days of receiving written notification from the department or the laboratory, the owner shall either:

a. Have completed corrective actions in accordance with the department approved CAP including department specified interim measures; or

b. Be in compliance with a department approved CAP and schedule.

(1) Any subsequent modifications to a department approved CAP and schedule shall also be approved by the department.

(2) If the department specifies interim measures for protection of the public health pending the department's approval of the CAP and schedule or pending completion of the CAP, then the owner shall comply with these interim measures as well as with any schedule specified by the department.

5. When a significant deficiency is identified at a water works that uses both a groundwater and a surface water or a GUDI source, the owner shall comply with this section unless the department has determined that the significant deficiency is in a portion of the distribution system that is served solely by the surface water or the GUDI source

B. The owner of a groundwater system that provides at least 4-log treatment of viruses before or at the first customer shall conduct compliance monitoring to demonstrate treatment effectiveness in accordance with subsection C of this section. The owner shall also conduct source water monitoring in accordance with 12VAC5-590-379 C.

The owner shall provide engineering, operational, or other information as required by the department to complete a determination of virus treatment effectiveness.

C. The owner of a groundwater system that provides at least 4-log treatment of viruses shall monitor the effectiveness and reliability of treatment for that groundwater source before or at the first customer as follows:

1. Chemical disinfection.

a. The owner of a groundwater system that serves greater than 3,300 people shall continuously monitor and record the residual disinfectant concentration using analytical methods specified in 12VAC5-590-440 at a location approved by the department and shall record the lowest residual disinfectant concentration each day that water from the groundwater source is served to the public. The owner shall maintain at least the department-determined residual disinfectant concentration every day the groundwater system serves water from the groundwater source to the public. If there is a failure in the continuous monitoring equipment, the owner shall conduct grab sampling every four hours until the continuous monitoring equipment is returned to service. The system shall resume continuous residual disinfectant monitoring within 14 days.

b. The owner of a groundwater system that serves 3,300 or fewer people shall monitor the residual disinfectant concentration using analytical methods specified in 12VAC5-590-440 at a location approved by the department and record the residual disinfection concentration each day that water from the groundwater source is served to the public. The owner shall maintain the department-determined residual disinfectant concentration every day the groundwater system serves water from the groundwater source to the public. The owner shall collect a daily grab sample during the hour of peak flow or at another time specified by the department. If any daily grab sample measurement falls below the department-determined residual disinfectant concentration, the owner shall collect follow-up samples every four hours until the residual disinfectant concentration is restored to the department-determined level. The owner of a groundwater system that serves 3,300 or fewer people may monitor continuously to meet the requirements of this subsection.

c. When the disinfection treatment is required based on confirmed E. coli contamination in the source water, the requirements in this section apply. When the disinfection treatment is required for any other reason or provided voluntarily by the owner, the department will determine the frequency of residual disinfectant monitoring.

d. Failure to maintain the department-specified minimum residual disinfectant concentration for a period of more than four hours is a violation of the treatment technique requirement.

2. The owner of a groundwater system that uses a department-approved alternative treatment to meet the requirements of this section by providing at least 4-log treatment of viruses before or at the first customer shall:

a. Monitor the alternative treatment in accordance with all department-specified monitoring requirements; and

b. Operate the alternative treatment in accordance with all department-specified compliance requirements necessary to achieve at least 4-log treatment of viruses.

3. Failure to meet the monitoring requirements of subsection C of this section is a violation and requires the owner to provide public notification as required in 12VAC5-590-540 A 3.

D. Discontinuing compliance monitoring or treatment.

1. The owner may discontinue compliance monitoring if the department determines and documents in writing that compliance monitoring is no longer necessary for that groundwater source. The owner of a groundwater systems that has department approval to discontinue compliance monitoring shall be subject to the triggered source water monitoring requirements of 12VAC5-590-379 B 1.

2. The owner of a groundwater system that is discontinuing compliance monitoring is still subject to the requirements of 12VAC5-590-380 G.

3. The owner that has been required by the department to provide at least 4-log treatment of viruses shall not discontinue treatment or monitoring.

Notes

12 Va. Admin. Code § 5-590-421

Derived from Virginia Register Volume 28, Issue 5, eff. December 7, 2011; Amended, Virginia Register Volume 37, Issue 20, eff. 6/23/2021.

Statutory Authority: §§ 32.1-12 and 32.1-170 of the Code of Virginia.