Virginia Administrative Code › Title 12 - HEALTH › Agency 5 - DEPARTMENT OF HEALTH › Chapter 613 - REGULATIONS FOR ALTERNATIVE ONSITE SEWAGE SYSTEMS › Part II - Performance Requirements › Section 12VAC5-613-80 - Performance requirements; general

Current through Register Vol. 40, No. 24, July 15, 2024
All AOSS designed, constructed, and operated pursuant to
					 this chapter shall comply with the following performance requirements unless
					 waived pursuant to
					 12VAC5-613-210:
1. The presence of raw or partially treated
				  sewage on the ground's surface or in adjacent ditches or waterways is
				  prohibited;
2. The exposure of
				  insects, animals, or humans to raw or partially treated sewage is
				  prohibited;
3. The backup of sewage
				  into plumbing fixtures is prohibited;
4. The direct dispersal of effluent into
				  ground water shall comply with
				  12VAC5-613-90 C;
5. All treatment units and treatment systems
				  shall be designed for the anticipated receiving wastewater characteristics and
				  peak flow;
6. Dosing of the
				  treatment unit or treatment system shall accommodate the design peak flow
				  within the treatment unit's rated capacity;
7. The AOSS shall be designed so that all
				  components are of sufficient structural integrity to minimize the potential of
				  physical harm to humans and animals;
8. The conveyance system for any AOSS shall
				  be designed and installed with sufficient structural integrity to resist inflow
				  and infiltration and to maintain forward flow;
9. The AOSS shall be designed to minimize
				  noise, odor, or other nuisances at the property boundary;
10. Maximum trench bottom hydraulic loading
				  rates for pressure-dosed systems using TL-2 and TL-3 effluent are found in
				  Table 1 and are to be used as follows:
a. The
				  designer is responsible for reducing loading rates according to the features
				  and properties of the soils in the soil treatment area as well as for reducing
				  loading rates for other types of dispersal;
b. Adherence to the maximum trench bottom
				  hydraulic loading rate criteria herein does not assure or guarantee that other
				  performance requirements of this chapter, including effluent dispersal or
				  ground water quality, will be met. It is the designer's responsibility to
				  ensure that the proposed design is adequate to achieve all performance
				  requirements of this chapter;
c.
				  Trench bottom hydraulic loading rates for pressure-dosed systems shall not
				  exceed the values in Table 1;
d.
				  Hydraulic loading rates shall be incrementally reduced from the TL-2 values in
				  Table 1 when a treatment unit or system is not designed to achieve TL-2 or
				  TL-3. In such cases, the designer shall, for monitoring purposes, specify the
				  effluent quality of the treatment unit. If the specified BOD5
				  exceeds 60 mg/l, the designer shall use loading rates for septic
				  tank effluent;
e. Trench bottom
				  hydraulic loading rates for gravity dosed systems shall be reduced from the
				  values in Table 1; and
f. Area
				  hydraulic loading rates for systems such as drip dispersal, pads, and mounds
				  shall be reduced from the values in Table 1 and shall reflect standard
				  engineering practice.
Table 1 Maximum Pressure-Dosed Trench
							 Bottom Hydraulic Loading Rates
Percolation Rate (MPI)
Saturated hydraulic conductivity (cm/day)
TL-2 Effluent (gpd/sf)
TL-3 Effluent (gpd/sf)
<=15
> 17
1.8
3.0
15 to 25
15 to 17
1.4
2.0
>25 to 45
10 to<15
1.2
1.5
>45 to 90
4 to<10
0.8
1.0
>90
< 4
0.4
0.5