Virginia Administrative Code › Title 12 - HEALTH › Agency 5 - DEPARTMENT OF HEALTH › Chapter 610 - SEWAGE HANDLING AND DISPOSAL REGULATIONS › Part IV - General Criteria for the Selection of a Wastewater Treatment and Disposal System Based on Site Conditions › Article 1 - Site Limitations › Section 12VAC5-610-593 - Physical features

Current through Register Vol. 40, No. 24, July 15, 2024
Physical features, landscape position and soil
						characteristics affect the ability of soil-based systems to treat and disperse
						effluent. In order to correctly select and place a sewage system in the
						environment such that public health and the environment are protected, it is
						necessary to understand and consider the local hydrologic conditions, the
						regional geology, and the nature of the soils occurring on the site being
						evaluated. At a minimum, the following features shall be considered:
1. Marshes and swamps. Placement of
					 subsurface soil absorption systems on or in swamps and marshes is
					 prohibited.
2. Seasonal water
					 table. A vertical separation distance between the point of effluent application
					 and a seasonal water table shall be maintained which reflects the quality of
					 the effluent and the receiving environment. Minimum vertical separation
					 distances may be found in Articles 2 (12VAC5-610-594 et seq.) and 3
					 (12VAC5-610-597 et seq.) of this
					 part and Tables 4.3 and 4.4.
3.
					 Slope. Subsurface soil absorption trench systems shall not be placed on slopes
					 greater than 50% unless terraced. Criteria for other types of onsite systems
					 are contained in Tables 4.3 and 4.4.
4. Drainage ways. Subsurface soil absorption
					 systems shall not be placed at a position in a drainage way subject to
					 intermittent flooding.
5. Fill
					 material. Placement of subsurface soil absorption systems in fill materials is
					 generally prohibited except in three specific situations. The Wisconsin Mound
					 system is considered a fill system as is the sand-on-sand system. These systems
					 are governed by criteria found in
					 12VAC5-610-960,
					 12VAC5-610-965, and Table 4.4.
					 Fill material consisting of colluvial soil derived from sandstone
					 (noncarbonaceous) in the mountainous area may be considered on a case-by-case
					 basis for placement of subsurface soil absorption systems.
6. Sink holes. Placement of a subsurface soil
					 absorption system at the low point of a sink hole is prohibited. For set back
					 distance see Table 4.2.
7. Flood
					 plains. Subsurface soil absorption systems shall not be placed in flood plains
					 subject to annual or more frequent sustained (24 hours) flooding.
8. Alluvial and colluvial deposits. Placement
					 of subsurface soil absorption areas in alluvial and colluvial deposits with
					 shallow depths, extended periods of saturation, or possible flooding is
					 prohibited.
9. Shrink-swell soils.
					 When soils containing horizons with shrink-swell characteristics (see
					 definitions in
					 12VAC5-610-120 ) have been
					 identified, they shall be rejected for use for subsurface soil absorption
					 systems.
10. Soil restrictions.
					 Soil restrictions in themselves may form the basis for outright rejection of
					 the site.
11. Free standing water.
					 The presence of free standing water in a profile hole may be grounds for
					 rejection of the site.
Statutory Authority
§§ 32.1-12 and 32.1-164 of the Code of
						  Virginia.