Virginia Administrative Code
Title 9 - ENVIRONMENT
Agency 25 - STATE WATER CONTROL BOARD
Chapter 740 - WATER RECLAMATION AND REUSE REGULATION
Part II - Reclaimed Water Treatment, Standards, Monitoring Requirements and Reuses
Section 9VAC25-740-70 - Treatment and standards for reclaimed water

Universal Citation: 9 VA Admin Code 25-740-70

Current through Register Vol. 41, No. 3, September 23, 2024

A. Treatment and standards for reclaimed water are provided in Table 70-A.

Table 70-A

Treatment and Standards for Reclaimed Water

1. Level 1

a. Treatment

Secondary treatment with filtration and higher-level disinfection.

b. Bacterial Standards

(1) Fecal coliform1: monthly geometric mean2 less than or equal to 14 colonies/100ml; corrective action threshold at greater than 49 colonies/100 ml; or

(2) E. coli1: monthly geometric mean2 less than or equal to 11 colonies/100 ml; corrective action threshold at greater than 35 colonies/100 ml; or

(3) Enterococci1: monthly geometric mean2 less than or equal to 11 colonies/100 ml; corrective action threshold at greater than 24 colonies/100 ml.

c. Total Residual Chlorine (TRC)3

Corrective action threshold at less than 1.0 mg/l4 after a minimum contact time of 30 minutes at average flow or 20 minutes at peak flow.

d. pH

6.0 - 9.0 standard units

e. Five-day Biochemical Oxygen Demand (BOD5)

(1) BOD5: monthly average less than or equal to 10 mg/l; or

(2) Carbonaceous Biochemical Oxygen Demand (CBOD5)5: monthly average less than or equal to 8 mg/l.

f. Turbidity6

Daily average of discrete measurements recorded over a 24-hour period less than or equal to 2.0 nephelometric turbidity units (NTU); corrective action threshold at greater than 5.0 NTU.

2. Level 2

a. Treatment

Secondary treatment and standard disinfection.

b. Bacterial Standards

(1) Fecal coliform1: monthly geometric mean2 less than or equal to 200 colonies/100ml; corrective action threshold at greater than 800 colonies/100 ml; or

(2) E. coli1: monthly geometric mean2 less than or equal to 126 colonies/100 ml; corrective action threshold at greater than 235 colonies/100 ml; or

(3) Enterococci1: monthly geometric mean2 less than or equal to 35 colonies/100 ml; corrective action threshold at greater than 104 colonies/100 ml.

c. Total Residual Chlorine (TRC)3

Corrective action threshold at less than 1.0 mg/l4 after a minimum contact time of 30 minutes at average flow or 20 minutes at peak flow.

d. pH

6.0 - 9.0 standard units

e. Five-day Biochemical Oxygen Demand (BOD5)

(1) BOD5: monthly average less than or equal to 30 mg/l; maximum weekly average 45 mg/l; or

(2) Carbonaceous Biochemical Oxygen Demand (CBOD5)5: monthly average less than or equal to 25 mg/l; maximum weekly average 40 mg/l.

f. Total Suspended Solids (TSS)

Monthly average less than or equal to 30 mg/l; maximum weekly average 45 mg/l.

1After disinfection.

2For the purpose of calculating the geometric mean, bacterial analytical results below the detection level of the analytical method used shall be reported as values equal to the detection level.

3Applies only if chlorine is used for disinfection.

4TRC less than 1.0 mg/l may be authorized by the department if demonstrated to provide comparable disinfection through a chlorine reduction program in accordance with the Sewage Collection and Treatment Regulations (9VAC25-790).

5Applies only if CBOD5 is used in lieu of BOD5.

6Where ultraviolet radiation will be used for disinfection of Level 1 reclaimed water, other turbidity standards may apply in accordance with 9VAC25-740-110 A 2 a.

B. Point of compliance (POC).

1. Reclaimed water produced by reclamation systems and SRSs for reuse shall meet all applicable standards in accordance with this chapter, excluding the turbidity standard for Level 1 treatment, at the POC. The POC for Level 1 and Level 2 treatment shall be after all reclaimed water treatment and prior to discharge to a reclaimed water distribution system. Where chlorination is used for disinfection of the reclaimed water, the POC for the TRC standard shall be the monitoring location specified in 9VAC25-740-80 A 2. The POC for the turbidity standard of Level 1 treatment shall be just upstream of disinfection.

2. Where the department determines that reclaimed water monitoring is required for a system storage facility or a reclaimed water distribution system, the number and location of POCs for these facilities shall be determined on a case-by-case basis and shall be described in the following documents for approval by the department:
a. For system storage facilities other than those considered part of reclaimed water distribution systems, in the operations and maintenance manual of the reclamation system or SRS where the storage facility is located; and

b. For reclaimed water distribution systems, including system storage facilities considered part of these systems, in the reclaimed water management plan pursuant to 9VAC25-740-100 C 1 h.

C. Reclaimed water that fails to comply with the standards shall be managed as follows:

1. Should reclaimed water reach the corrective action threshold (CAT) for turbidity in the standard for Level 1, or for TRC in the standards for Level 1 or 2, whichever applies, the operator of the reclamation system shall immediately initiate a review of treatment operations and data to identify the cause of the CAT monitoring results to bring the reclaimed water back into compliance with the standards. Resampling or diversion shall occur within one hour of first reaching the CAT. Procedures for resampling, operational review and diversion shall be as described in an approved operations and maintenance manual for the reclamation system. If subsequent monitoring results of the resamples collected within one hour of the first CAT monitoring results for turbidity or TRC continue to reach the CAT of the standards, the reclaimed water shall be considered substandard or reject water and shall be diverted to either storage for subsequent additional treatment or retreatment, or discharged to another permitted reuse system requiring a lower level of treatment not less than Level 2 or to a VPDES permitted effluent disposal system provided the reject water meets the effluent limits of the permit. If the reclamation system is unattended, the diversion of reject water shall be initiated and performed with automatic equipment. There shall be no automatic restarts of distribution to reuse until the treatment problem is corrected. Failure to divert the substandard or reject water after one hour of CAT monitoring results shall be considered a violation of this chapter. Upon resuming discharge of reclaimed water to the reclaimed water distribution system for which the CAT was reached, resampling for turbidity or TRC shall occur within one hour to verify proper treatment.

2. Should reclaimed water reach the CAT for bacteria (i.e., fecal coliform, E. coli or enterococci) in the standards for Level 1 or 2, whichever applies, the operator of the reclamation system shall immediately initiate a review of treatment operations and data to identify the cause of the CAT monitoring results to bring the reclaimed water back into compliance with the standards. Procedures for operational review shall be as described in an approved operations and maintenance manual for the reclamation system. Two consecutive bacterial monitoring results that reach the CAT of the standards shall be considered a violation of this chapter.

3. Repeated, although temporary, failure to comply with all other standards by the reclamation system may be considered a violation of this chapter determined by the frequency and magnitude of the noncompliant monitoring results and other relevant factors. Failure to resample after determination that monitoring results are not in compliance with the standards, to make adjustments to the treatment process to bring the reclaimed water back into compliance with the standards, or to divert substandard or reject water in accordance with subdivision 1 of this subsection shall be considered a violation of this chapter.

D. Treatment or standards other than or in addition to the treatment and standards in subsection A of this section may be necessary based on the quality and character of the wastewater to be reclaimed or the intended reuse or reuses of the reclaimed water. Such alternative or additional treatment or standards may be exempt from this chapter unless required by the department to protect public health and the environment.

E. Standards for the reclamation of industrial wastewater shall be determined on a case-by-case basis relative to the proposed reuse or reuses of the reclaimed water and for the purpose of protecting public health and the environment. Industrial wastewater may also be subject to disinfection requirements of Level 1 or Level 2 if the industrial wastewater contains sewage or is expected to contain organisms pathogenic to humans, such as, but not limited to, wastewater from the production and processing of livestock and poultry. The point of compliance for reclamation standards of industrial wastewater shall also be determined on a case-by-case basis.

Statutory Authority: § 62.1-44.15 of the Code of Virginia.

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