Glossary

12VAC5-610: The Sewage Handling and Disposal Regulations — Virginia's core rules for conventional onsite sewage systems, adopted under §§ 32.1-12 and 32.1-164 of the Code of Virginia.

12VAC5-613: Regulations for Alternative Onsite Sewage Systems, effective December 7, 2011. Sets performance requirements, operation and maintenance duties, and permitting for AOSS.

9VAC25-830: The Chesapeake Bay Preservation Area Designation and Management Regulations, which contain the requirement that onsite systems in a CBPA have pump-out accomplished at least once every five years.

AOSS: Alternative Onsite Sewage System. A system using treatment beyond a conventional septic tank and drainfield, regulated under 12VAC5-613 with stricter performance standards and mandatory operator visits.

Baffle: A barrier inside the septic tank controlling flow between compartments and keeping solids from reaching the drainfield.

CBPA: Chesapeake Bay Preservation Area. Land designated by a locality under the Chesapeake Bay Preservation Act where improper development could harm water quality. Systems inside one require pump-out at least every five years.

Certification Letter: A VDH document indicating a site is suitable for an onsite sewage treatment and disposal system. The application process and fees mirror those for a system application under 12VAC5-610-250.

Construction Permit: The written permit from the commissioner required before constructing, expanding or modifying a sewage disposal system. No system work may lawfully proceed without one.

DPOR: The Virginia Department of Professional and Occupational Regulation, which licenses onsite soil evaluators, onsite sewage system operators, and installers.

Drainfield: Where treated effluent disperses into soil for final treatment. Also called an absorption area or soil treatment area.

Grab Sample: A single wastewater sample taken at one moment. Under 12VAC5-613-70, VDH may not rely solely on an individual grab sample to establish a violation, absent other evidence of failure.

Grandfathered Lot: A lot where an owner may apply for a construction permit and receive one for a system complying to the greatest extent possible, provided site and soil conditions would not preclude successful operation.

HB 2671: The 2025 law (Chapter 103, signed March 20, 2025, effective July 1, 2025) that set minimum standards and accreditation requirements for septic inspections. It does NOT require an inspection at point of sale — it governs what one must contain when requested.

O&M Manual: Required under 12VAC5-613-170 before an AOSS operation permit issues. Must be understandable to any potential owner and cover design details, component list, site layout, sampling locations, schedules and design limits.

Onsite Soil Evaluator: A DPOR-licensed professional who conducts site and soil evaluations and designs onsite systems. Under 18VAC160-10, a licensed person must perform the site assessment and design.

Operation Permit: The permit authorizing a system to operate. For an AOSS, VDH will not issue one until the owner records an instrument in circuit court land records and has established a relationship with a licensed operator.

Operator: A DPOR-licensed professional who visits, maintains and reports on an AOSS. Visit frequency for systems up to 40,000 GPD is set by Table 4 of 12VAC5-613.

Project Area Boundary: The point at which AOSS performance is measured. Fecal coliform must not exceed 2.2 cfu/100 ml at the lower vertical limit of this boundary.

Renewable Operation Permit: An operation permit that must be renewed rather than issued once. Under 12VAC5-613, these apply only to AOSSs with applications filed on or after December 7, 2011.

Riser: An extension bringing a buried tank access lid to grade. Typically $200 to $400, and it pays for itself within about two pump-outs by removing the excavation charge.

Sewage Handling and Disposal Appeals Review Board: The body established under § 32.1-166.1 of the Code of Virginia to hear appeals of VDH decisions on sewage handling and disposal.

Vertical Separation: The depth of suitable soil beneath the drainfield before reaching a limiting condition such as bedrock or the seasonal water table. Limited separation is a common reason a site requires an alternative system.

VDH: The Virginia Department of Health, which sets onsite sewage rules statewide. Local health departments issue construction and operation permits.