15.07.070 Soil and site evaluations.
(1) General. Soil and site information must be conducted for all divisions of land to the satisfaction of the Sanitarian to insure that each parcel being subdivided must have suitable soil conditions to accommodate an on-site waste disposal system. The soil suitability and anticipated system types will dictate to what extent soil and site evaluations must be conducted and reported to the Sanitarian. Where required in this section, complete soil and site evaluations must be conducted in accordance with Ch. Comm. 85 of the Wisconsin Administrative Code.
(2) Soil Borings. Soil borings shall be dug preferably by a backhoe and constructed large enough and deep enough to enable an evaluator and the Sanitarian to determine soil suitability. Number of borings will vary dependent on the type of soil being evaluated.
(a) Soils with Redoximorphic Features Less that Forty-Eight (48) Inches. Proposed lots or parcels that typically have a seasonal high groundwater table based on redoximorphic soil features less than forty-eight (48) inches will require a minimum of three (3) soil borings that have suitable soil characteristics and are grouped to identify a proposed system area. However, on a preliminary plat one (1) suitable boring per lot shall be acceptable. A complete soils and site evaluation report will be required for each lot for final plat approval.
(b) Soils with Redoximorphic Features of Forty-Eight (48) Inches or Greater. Proposed lots or parcels that typically have a seasonal high groundwater table based or redoximorphic soil features of forty-eight (48) inches or greater will require a minimum of one (1) soil boring per three (3) acres if the soil characteristics remain consistent with the soil mapping unit. Except that complete soil and site evaluations must be performed when parcels are being divided via a certified survey map procedure or unplatted land divisions.
(c) Variable Soil Types. Landscapes with variable soil types and depths to seasonal high groundwater that are being platted will provide enough soil suitability information in the form of random soil borings and complete soil and site evaluations to insure suitable soils for a POWTS with a dispersal cell on every proposed lot or parcel.
(d) Consultation with the Sanitarian. A soil and site evaluation consultation meeting with the Sanitarian to determine what may be the best approach to evaluating a particular landscape may be necessary before performing any fieldwork.
(e) Depth of Soil Borings. Depth of soil borings may vary dependent on soil type and suitability.
1. Proposed inground POWTS shall have a minimum boring depth of seven (7) feet or to bedrock if present at a lesser depth. All borings in this category shall be excavated to at least four (4) feet below the anticipated system elevation.
2. Proposed shallow inground POWTS may have borings excavated to a minimum of five (5) feet
3. Proposed at-surface POWTS shall have borings excavated to a minimum of three (3) feet.
4. The depth of a soil boring shall be referenced to the final grade of the subdivision.
(f) Elevations. All soil borings shall have a ground surface elevation referenced to a permanent benchmark established by the evaluator or to mean sea level.
(3) Soil Profile Descriptions. All soil borings excavated for a particular land division or plat shall be noted and described adequately using soil profile description criteria in accordance with Ch. Comm 85 of the Wisconsin Administrative Code.
(4) Soil Saturation Determinations. Soil evaluations of this type may be necessary to determine actual depths to seasonal high groundwater and can be done by a licensed person as an interpretive determination or a soil saturation determination.
(a) Hydric Soils. These methods shall not be used to interpret hydric soils for a land division unless it has been determined by the Sanitarian that the soils of the site in question do not meet the definition of hydric soils and may be an inclusion to the soil mapping unit or a mis-mapped area.
(b) Determination Prior to County Approval. Any site evaluated utilizing soil saturation determination to interpret a non-conforming site must be conducted with the results approved by the Department prior to submittal of the plat or land division. This procedure cannot be performed to dispute a soil condition that does not meet the A+4 soil criteria unless otherwise approved by the Sanitarian.
(c) Interpretive Determination. Evaluation of soil conditions for purposes of this section may be conducted by approval of the Sanitarian and only if the A+4 soil criteria has been met. However, the Sanitarian may grant approval for interpretation only if evidence has been presented and determined in the field that the site in question is not meeting a hydric soil definition or it may be a mapping inclusion or a mis-mapped soil type.
(d) Approval. All soil saturation determination procedures performed for purposes of dividing land must be pre-approved by the Sanitarian and must be in accordance with Ch. Comm. 85 of the Wisconsin Administrative Code. Final approval of the soil saturation data shall be in writing from the Department of Commerce. [Code § 15.07-7, 2018.]