South Carolina Code of Regulations › Chapter 61 - DEPARTMENT OF HEALTH AND ENVIRONMENTAL CONTROL › Subchapter 61-56 - ONSITE WASTEWATER SYSTEMS › Section 61-56.400 - Appendices of Standards for Permitted Systems › Appendix 61-56.400.R - Curtain Drain Standard

Current through Register Vol. 48, No. 6, June 28, 2024
(1) Minimum Construction Requirements
(a) Only pipe having received written approval from the
				  Department may be utilized in curtain drains. This approval shall be based upon
				  the pipe meeting all applicable ASTM standards.
(b) The aggregate used in curtain drains shall be a material
				  approved by the Department.
(c) The curtain drain trench utilizing tire chips or gravel
				  or a similar type of Department approved product shall be at least six (6)
				  inches wide.
(d) The curtain drain shall be placed ten (10) feet upslope
				  and twenty-five (25) feet downslope of a subsurface wastewater infiltration
				  area or repair area. Where the aggregate portion of the curtain is installed at
				  the same or lower (downslope) elevation relative to an adjacent subsurface
				  wastewater infiltration area or repair area, the aggregate portion of the
				  curtain must be a minimum of twenty-five (25) feet from the adjacent subsurface
				  wastewater infiltration area or repair area.
(e) The trench bottom shall have a uniform slope to the
				  discharge point. Trench excavation with a ditch witch is permissible provided
				  the trench bottom has a uniform downslope gradient.
(f) The solid discharge (non-aggregate) line shall be fifteen
				  (15) feet from adjacent subsurface wastewater infiltration area or repair
				  area.
(g) The downslope side of the trench toward the subsurface
				  wastewater infiltration area shall have a minimum six (6) mil poly or an
				  equivalent strength treated impervious material draped from the trench surface
				  to the trench bottom to prevent groundwater from bridging the curtain
				  drain.
(h) Agricultural drainpipe (slitted) with a minimum diameter
				  of four (4) inches shall be placed along the trench bottom in the aggregate
				  portion. Perforated pipe is acceptable, provided the perforations are installed
				  facing either sideways or upward.
(i) There shall be at least two (2) inches of aggregate
				  beneath the drainpipe.
(j) The aggregate shall be brought to at least six (6) inches
				  from the ground surface.
(k) The aggregate shall be covered with a strong, untreated
				  pervious material to prevent infiltration of back fill material.
(l) Solid drainpipe with a minimum diameter of four (4)
				  inches shall be placed along the trench bottom from the aggregate to the
				  discharge point.
(m) The curtain drain must discharge to the ground surface
				  past the last wastewater infiltration trench line.
(n) Rodent barriers on discharge pipe outlet(s) are
				  required.
(o) If the curtain drain's trench bottom depth exceeds thirty
				  (30) inches, it shall be inspected prior to the aggregate being installed to
				  ensure proper trench depth and grade. It is acceptable to place the pipe and
				  aggregate in the trench prior to the final inspection when a probe rod
				  inspection port can be used to accurately measure trench bottom depth.
Click to
				  view image
Click to
				  view image
Click to
				  view image