The purpose of this rulemaking is to provide for a revised method to estimate wastewater flow from single family dwellings that is more consistent with domestic water usage statewide. The proposed revisions would provide for a more refined soil classification system which will allow more precise sizing of drainfields. The rule would also provide a definition of "bedroom" and "module" to assist understanding and applicability of the rule within the regulated community.

The proposed rule includes the following:

1. Add a definition for the terms "bedroom" and "module";
2. Revise the wastewater flow rates for single family dwellings (Subsection 007.08);
3. Refine the soil classification system from 3 to 6 soil types (Subsections 008.02 and 008.03); and
4. Revise the maximum total square feet of trench (Subsection 008.04).  In order to be in balance with the increased wastewater flow rates, it is necessary to increase the maximum allowable size for a standard drainfield.

After consideration of public comments, the definition of "module" has been revised (Section 003).  The remainder of the rule has been adopted as proposed.

August 6 through September 3, 2008

> View Proposed Rule (pdf format).