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

Current through Register Vol. 40, No. 24, July 15, 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.