1. (1) General conditions for approval. Construction-installation permits may be issued for steep slope systems serving single-family dwellings on slopes in excess of 30 percent if all the following requirements can be met.

   1. (a) Slope does not exceed 45 percent.
   2. (b) The soil is well-drained with no evidence of saturation to a depth of 60 inches.
   3. (c) The soil has a minimum effective soil depth of 60 inches.

2. (2) Construction requirements.

   1. (a) Seepage trenches must be installed at a minimum depth of 30 inches and a maximum depth of 36 inches below the natural soil surface on the downhill side of the trench and must contain a minimum of 18 inches of drain media and 12 inches of native soil backfill.
   2. (b) The system must be sized at a minimum of 75 linear feet per 150 gallons sewage flow.

Statutory/Other Authority

ORS 454.625 & 468.020

Statutes/Other Implemented

ORS 454.615 & 454.775

History

DEQ 29-2025, amend filed 10/01/2025, effective 01/01/2026
DEQ 11-2004, f. 12-22-04, cert. ef. 3-1-05
DEQ 9-1984, f. & ef. 5-29-84
DEQ 8-1983, f. & ef. 5-25-83
DEQ 10-1981, f. & ef. 3-20-81