Soil and Site Evaluation: Spray Irrigation

Soil and Site Evaluation: Spray Irrigation. 1. A satisfactory soil and site evaluation will comply with the following criteria: a. Absence of or protection from frequent flooding. b. Landscape position with positive surface runoff. c. Slopes of less than sixteen (16)%. d. Depth to high water table of greater than six (6) inches. e. Depth to bedrock, fragipan, redoximorphic features or plinthite of greater than twelve (12) inches. f. Soil texture and color defined by the Natural Resource Conservation Service as indicating good drainage and suitable for surface application of wastewater, based on a soil boring of five (5) feet. 2. Sizing of the spray disposal field will be based on the most restrictive soil within twelve (12) inches of the naturally occurring ground surface. [See Table 16.] 3. To overcome the lack of sufficient depth to a restrictive horizon and/or Seasonal High Water Table, a clean fill material of a texture of sandy loam may be used as fill material. Organic matter shall be removed from the native soil surface prior to placing and incorporating the fill. This fill must be incorporated into the native soil to prevent a textural interface from developing. When fill material is used the entire fill area must be sodded to prevent erosion, or other effective erosion control methods used. The full depth of fill material must extend at least ten (10) feet in all directions from the outer edge of the spray field and at that point shall be sloped at a grade of no steeper than 3 to 1. [See Table 17.] 4. The noncompliance of one or more of the above items may (1) require a design alteration or (2) prohibit the use of a Spray Irrigation Disposal system. Slopes of greater than sixteen (16)% may be considered on a case-by-case basis.