9VAC25-740-80. Reclaimed water monitoring requirements for reuse.
A. The monitoring requirements for the standards provided under 9VAC25-740-70 A, are as follows:
1. Turbidity analysis:
a. Analysis shall be performed by a continuous, on-line turbidity meter equipped with an automated data logging or recording device and an alarm to notify the operator when the CAT for turbidity in the standard for Level 1 has been reached. Compliance with the average turbidity standard shall be determined daily, based on the arithmetic mean of hourly or more frequent discrete measurements recorded during a 24-hour period. Monitoring for the turbidity CAT shall be continuous.
b. Should the on-line turbidity meter go out of service for either planned or unplanned repair, the permittee shall be allowed to manually collect samples for turbidity analysis at four-hour intervals up to a maximum of five days. Following the five-day period of repair, continuous, on-line monitoring with a turbidity meter shall resume.
2. Sampling and analysis for residual concentrations of disinfectants, including total residual chlorine (TRC):
a. For Level 1:
(1) Shall be continuous on-line monitoring, equipped with an automated data logging or recording device and an alarm to notify the operator when the CAT for the disinfectant has been reached. For disinfectants other than chlorine, continuous on-line monitoring shall be provided at the point of compliance monitoring. For TRC, continuous on-line monitoring shall be provided at the end of the contact tank or contact period. Monitoring for the TRC CAT shall be continuous.
(2) Should the on-line disinfectant monitoring equipment go out of service for either planned or unplanned repair, the permittee shall be allowed to manually collect samples for disinfectant analysis at four-hour intervals up to a maximum of five days. Following the five-day period of repair, continuous, on-line disinfectant monitoring shall resume.
b. For Level 2, shall be based on the designated design flow of the reclamation system and be the same sampling type and frequency as specified for sewage treatment works in the Sewage Collection and Treatment Regulations (9VAC25-790). For chemical disinfectants other than TRC, monitoring shall be provided at the point of compliance in accordance with 9VAC25-740-70 B. For TRC, monitoring shall be provided at the end of the contact tank or contact period.
3. Sampling for TSS and BOD5 or CBOD5 shall be at least weekly or more frequently based on the designated design flow of the reclamation system, and shall be the same sampling type and frequency as specified for sewage treatment works in the Sewage Collection and Treatment Regulations (9VAC25-790). Compliance with the monthly average TSS and BOD5 or CBOD5 standards shall be determined monthly, based on the arithmetic mean of all samples collected during the month. Compliance with the maximum weekly average TSS and BOD5 or CBOD5 standards shall be determined monthly, using the same procedures applied in the VPDES permit program for point source discharges.
4. Sampling for fecal coliform, E. coli or enterococci:
a. Shall for Level 1, be grab samples collected at a time when wastewater characteristics are most representative of the treatment facilities and disinfection processes for water reuse, and at the frequencies provided in Table 80-A. Compliance with the geometric mean standards for fecal coliform, E. coli, or enterococci shall be determined monthly, based on all bacteriological monitoring results for that month. Monitoring of the CAT for fecal coliform, E. coli, or enterococci shall be based on the bacteriological monitoring results determined for each day a sample is collected.
Table 80-A | |
Reclamation System Designated Design Flow (MGD)(1) | Bacterial Sampling Frequency(2) |
>0.500 | Daily with the ability to reduce to no less than four days per week(3) |
0.050 to 0.500 | Four days per week with the ability to reduce to no less than three days per week(3) |
<0.050 | Three days per week with no reduction allowed |
(1)MGD means million gallons per day. (2)For reclamation systems treating municipal wastewater, bacterial samples shall be collected between 10 a.m. and 4 p.m. to coincide with peak flows to the reclamation system. An exception to this requirement may be approved upon demonstration to the department that peak flows to the reclamation system occur outside this period. (3)Monitoring frequency may be reduced after demonstrating compliance with bacterial standards for Level 1 and adequate correlation between bacterial monitoring results and measurements for surrogate disinfection parameters, such as TRC and turbidity. | |
b. Shall for Level 2, be based on the designated design flow of the reclamation system and be the same sampling type and frequency as specified for sewage treatment works in the Sewage Collection and Treatment Regulations (9VAC25-790). Compliance with the geometric mean standard and monitoring of the CAT for fecal coliform, E. coli or enterococci shall be in accordance with the same procedures specified for Level 1 in subdivision 4 a of this subsection.
5. Samples for pH shall be grab samples collected at least daily. Compliance with the range of the pH standard shall be determined daily based on the pH of the samples.
B. Samples collected for TSS, BOD5 or CBOD5, and fecal coliform, E. coli or enterococci analyses, shall be analyzed by laboratory methods accepted by the department.
C. A reclamation system that produces reclaimed water intermittently or seasonally shall monitor only when the reclamation system discharges to a reclaimed water distribution system, a nonsystem storage facility, or directly to a reuse.
D. Monitoring of reclaimed water held in system storage for a period greater than 24 hours at a reclamation system or SRS may be required by the department where (i) the system storage facility discharges to a reclaimed water distribution system, a nonsystem storage facility, or directly to a reuse; and (ii) conditions exist at the facility to degrade the reclaimed water to a quality failing to comply with applicable minimum reclaimed water standards for the intended reuses of that water. When monitoring of reclaimed water in or from system storage is required, monitoring parameters and frequencies shall be determined by the department on a case-by-case basis.
E. Monitoring other than or in addition to that described under subsection A of this section may be required for treatment of reclaimed water that is provided pursuant to 9VAC25-740-70 D and 9VAC25-740-70 E.
Statutory Authority
§ 62.1-44.15 of the Code of Virginia.
Historical Notes
Derived from Virginia Register Volume 24, Issue 26, eff. October 1, 2008; amended, Virginia Register Volume 30, Issue 9, eff. January 29, 2014; Volume 39, Issue 5, eff. November 23, 2022.