12 Va. Admin. Code § 5-640-400

Current through Register Vol. 41, No. 6, November 4, 2024

Section 12VAC5-640-400 - Classifications of discharge points

The nature of the discharge point will determine what precautions must be taken to protect public health and environmental resources.

1. Where an all weather stream is available, it shall be used rather than discharging to an intermittent stream, dry ditch, or wetland. An all weather stream can readily dilute the effluent at least 10:1 at the seven consecutive day average of a 10-year low flow (7-Q-10) and thereby minimize public health and water quality impacts.

2. An all weather stream is represented by a solid blue line on the most recently published 7.5 minute United States Geologic Survey topographic map and has a 7-Q-10 flow that can provide 10:1 dilution of the effluent. Intermittent streams are represented by a dotted and dashed blue line on the most recently published 7.5 minute United States Geologic Survey topographic map. An all weather stream that provides less than 10:1 dilution of the effluent based on 7-Q-10 flow shall be considered an intermittent stream. Intermittent streams and dry ditches have an assigned stream flow 7-Q-10 of zero.

3. An owner may submit to the division additional hydrologic data, including but not limited to stream records and anecdotal evidence of long time residents, to support that a stream can provide a dilution ratio of 10:1. When in the opinion of the division, the evidence warrants a change, the division may determine that a stream is an all weather stream for the purposes of this chapter. The owner may also request site specific stream flow determinations from the Department of Environmental Quality.

4. Discharges into intermittent streams or dry ditches that do not have the dilution capability cited in subdivision 1 of this section shall be located entirely within the owner's property, or within a recorded easement as described in subdivision 2 of 12VAC5-640-450.

a. The average slope for any intermittent stream or dry ditch discharge receiving effluent from a discharging system shall be a minimum of 2.0% for the first 500 feet from the point of discharge. The intermittent stream or dry ditch shall be protected from erosion by the discharge as needed.

b. In order to prevent ponding, the minimum slope shall not be less than 1.0% at any point.

c. All slope measurements described in subdivisions 1 and 2 of this section shall be made prior to initiating any grading and are intended to reflect naturally occurring swales and drainage ways. Nothing contained herein however, is intended to prohibit a property owner from making minor grading improvements to prevent ponding in areas with minimal slopes. Naturally occurring swales and drainage ways may be extended with an engineered channel on a case-by-case basis, but any engineered channel must tie into the existing natural swale or drainage.

5. Wetlands shall be confirmed by the U.S. Army Corps of Engineers or the Department of Environmental Quality, as appropriate, based on the type of wetland. Confirmation of delineated wetlands shall be provided and include a wetland delineation map, wetland field data sheets, and any other documentation from the U.S. Army Corps of Engineers or the Department of Environmental Quality indicating their approval of the wetland boundary. 7-Q-10 flows cannot be calculated for wetlands and therefore the assigned 7-Q-10 flow value is zero. Discharges to wetlands shall be located entirely within the owner's property, or within a recorded easement as described in subdivision 2 of 12VAC5-640-450.

12 Va. Admin. Code § 5-640-400

Amended, Virginia Register Volume 32, Issue 06, eff. 12/16/2015.

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