Virginia Administrative Code › Title 12 - HEALTH › Agency 5 - DEPARTMENT OF HEALTH › Chapter 613 - REGULATIONS FOR ALTERNATIVE ONSITE SEWAGE SYSTEMS › Part II - Performance Requirements › Section 12VAC5-613-90 - Performance requirements; ground water protection

Current through Register Vol. 40, No. 24, July 15, 2024
A. The AOSS shall not pose a greater risk of
				  ground water pollution than systems otherwise permitted pursuant to 12VAC5-610.
				  After wastewater has passed through a treatment unit or septic tank and through
				  the soil in the soil treatment area, the concentration of fecal coliform
				  organisms shall not exceed 2.2 cfu/100 ml at the lower vertical limit of the
				  project area boundary.
B. Each
				  large AOSS shall comply with TN limit of 5 mg/l at the project area boundary.
				  Prior to the issuance of a construction permit, the designer shall demonstrate
				  compliance with this requirement through modeling or other calculations. Such
				  demonstration may incorporate multiple nitrogen removal methods such as
				  pretreatment, vegetative uptake (only for AOSSs with shallow soil treatment
				  areas), denitrification, and other viable nitrogen management methods. Ground
				  water and other monitoring may be required at the department's
				  discretion.
C. AOSSs with direct
				  dispersal of effluent to ground water are subject to the following
				  requirements:
1. If the concentration of any
				  constituent in ground water is less than the limits set forth at 9VAC25-280,
				  the natural quality for the constituent shall be maintained; natural quality
				  shall also be maintained for all constituents not set forth in 9VAC25-280. If
				  the concentration of any constituent in ground water exceeds the limit in the
				  standard for that constituent, no addition of that constituent to the naturally
				  occurring concentration shall be made. The commissioner shall consult with the
				  Department of Environmental Quality prior to granting any variance from this
				  subsection.
2. Ground water and
				  laboratory sampling in accordance with
				  12VAC5-613-100
				  G.
3. The treatment unit or system
				  shall comply with the following at a minimum:
a. The effluent quality from the treatment
				  unit or system shall be measured prior to the point of effluent application to
				  the soil treatment area and shall be as follows: BOD5
				  and TSS concentrations each equal to or less than 5 mg/l; fecal coliform
				  concentrations less than or equal to 2.2 col/100 ml as a geometric mean with no
				  sample exceeding 14 col/100 ml; and TN concentration of less than 5 mg/l;
b. High level disinfection is
				  required; and
c. Treatment systems
				  shall incorporate filtration capable of demonstrating compliance with an
				  average turbidity of less than or equal to 2 NTU prior to
				  disinfection.
4. Gravity
				  dispersal to the soil treatment area is prohibited.
5. Loading rates to the soil treatment area
				  shall not exceed the loading rates in Table 1 of
				  12VAC5-613-80.
6. A renewable operating permit shall be
				  obtained and maintained in accordance with
				  12VAC5-613-60
				  C.
7. The designer shall provide
				  sufficient hydrogeologic analysis to demonstrate that a proposed AOSS will
				  function as designed for the life of the structure served without degradation
				  of the soil treatment area. This shall include a determination of ground water
				  flow direction and rate.