Clean soil refers to soil that is free from contaminants resulting from a release. It also includes soil that contains one or more contaminants from a release and has been transported from one location to another for placement onto or into the ground. This soil is considered clean if it meets either of the following criteria:

 

(a) It does not contain contaminants that exceed a cleanup level under chapter 173-340 WAC, Model Toxics Control Act-Cleanup, that would be established for the existing land use at the location where the soil is placed.

 

(b) It contains contaminants that affect pH, but the pH of the soil is within natural background pH limits that exist at the location where the soil is placed, which is between 4.5 and 9.5.

 

Examples of potentially clean soil include but are not limited to, soil from undeveloped lands that are unlikely to have been impacted by the release of contaminants associated with area-wide or local industrial or historical activities. This also includes similar soils over which development may have occurred, but land use is unlikely to have led to a release, such as use for residential housing or coverage by pavement. Soil with substances from natural background conditions, as defined in WAC 173-350-100, is also considered clean soil under this section.

We abide by the Washington State Legislation rules and definition of Clean soil:  WAC 173-350-100