12 Va. Admin. Code § 5-610-960

Current through Register Vol. 40, No. 22, June 17, 2024

Section 12VAC5-610-960 - Elevated sand mound

A. An elevated sand mound is a soil absorption system that incorporates low pressure distribution and sand filtration to produce treated sewage prior to absorption in the natural underlying soil. The elevated sand mound utilizes less gross soil area than most other soil absorption systems. Elevated sand mounds differ from pads in that elevated sand mounds are always an aboveground system, may receive septic tank effluent, and always require pressure distribution, and the infiltrative surface follows the natural ground surface and contour of the site.

B. Mound systems receiving septic tank effluent shall be designed and constructed in accordance with the Wisconsin Mound Soil Absorption System Siting, Design and Construction Manual prepared by the Small Scale Waste Management Project, School of Natural Resources, College of Agricultural and Life Sciences, University of Wisconsin-Madison dated January 2000. Drip dispersal or low pressure distribution shall be used.

C. The manual referred to in subsection B of this section shall be used for the designated construction of elevated sand mounds. The following criteria are required for all elevated sand mound systems in addition to the requirements found in the manual.

1. The proposed mound site shall be fenced, roped, or otherwise secured, and marked, to prevent damage by vehicular traffic. Activities on the mound site shall be severely limited in order to protect it to the greatest extent possible.

2. The mound must be constructed during dry weather and soil conditions.

3. Wooded sites shall not be used unless it is shown by the applicant that the wooded site is the only site available, and if the applicant can demonstrate that the site can be properly prepared. If a wooded site is used, trees shall be removed by cutting them off at ground level, leaving the stumps in place. The cut trees shall be removed using methods that do not require driving equipment over the mound site and that do not result in the removal of any soil from the site. Larger basal areas may be required on wooded sites.

4. When the depth to a restriction, shrink-swell soils, or a water table is less than 24 inches, pretreatment sufficient to produce TL-2 effluent or TL-3 effluent may be used to reduce these distances. in accordance with 12VAC5-613-80.

5. The minimum absorption area for single family residential dwellings shall be 400 square feet.

D. Elevated sand mounds receiving TL-2 effluent or TL-3 effluent shall adhere to the following additional design criteria.

1. The basal area (interface of fill sand and original soil surface) loading rate shall not exceed the values found in Table 5.5.

2. The minimum sand depth under the dispersal system is six inches.

3. The minimum soil cover, after settling, shall be six inches as measured from the finished ground surface to the uppermost limit of the dispersal media (or gravelless material) utilized in the absorption area. The finished sideslopes cannot exceed 1:4 (rise:run). The soil cover, with amendments as needed, shall be of a quality, character, and fertility suitable to establish a vegetative cover that is uniform and sufficiently mature to survive and inhibit erosion.

4. Vertical separation to limiting features as found in 12VAC5-613-80 shall be maintained under the entire infiltrative surface of the basal area.

5. Designs supported by division approved manufacturer design manuals may deviate from pressure dosing but require dosing to a gravity distribution system at a minimum.

12 Va. Admin. Code § 5-610-960

Derived from VR355-34-02 §4.31, eff. February 5, 1986; amended, eff. May 11, 1988; Virginia Register Volume 16, Issue 16, eff. July 1, 2000; Amended, Virginia Register Volume 39, Issue 4, eff. 11/24/2022; Errata, 39:6 VA.R. 985 November 7, 2022.

Statutory Authority: §§ 32.1-12 and 32.1-164 of the Code of Virginia.