Cap and fill drainfield in Polk County, OR

A cap and fill drainfield is needed when your soil does not have enough depth between the trench bottom and a limiting layer such as heavy clay, rock, or high groundwater. A site evaluation by Polk County Environmental Health will confirm which design applies to your lot.

The drainfield area is scarified to remove all vegetation, including ten feet beyond the trench edges. This step creates a good contact surface so the fill bonds properly with the native soil.

Yes, cap and fill drainfields can be installed on sloped ground, but the trenches must follow the exact contour of the slope to work correctly. Precise grading is required, which is why experienced excavation work matters on these sites.

Oregon DEQ requires the fill to be graded evenly to a depth of 10 to 16 inches over the drain media, depending on the distribution type used. The fill must also extend at least ten feet beyond the drainfield trenches on all sides.

Yes, a cap and fill system requires additional inspections and more labor than a standard drainfield because of the fill placement and grading steps involved. Polk County Environmental Health conducts both a pre-cover and a post-cover inspection before the work is complete.

Iron Edge Excavation serves Polk County and surrounding areas including Salem, Sheridan, Willamina, and Amity for cap and fill drainfield installation. Call us to set up a site visit and get the process started.