North Carolina Administrative Code › Title 15A - Environmental Quality › Chapter 18 - ENVIRONMENTAL HEALTH › Subchapter A - SANITATION › Section .1900 - SEWAGE TREATMENT AND DISPOSAL SYSTEMS › Section 18A .1941 - SOIL CHARACTERISTICS (MORPHOLOGY)

Current through Register Vol. 39, No. 2, July 15, 2024
(a)
				  The soil characteristics which shall be evaluated by the local health
				  department are as follows:
(1) Texture - The
				  relative proportions of sand, silt, and clay sized mineral particles in the
				  fine-earth fraction of the soil are referred to as soil texture. The texture of
				  the different horizons of soils shall be classified into four general groups
				  and 12 soil textural classes based upon the relative proportions of sand, silt,
				  and clay sized mineral particles.
(A) SOIL
				  GROUP I - SANDY TEXTURE SOILS. The sandy group includes the sand and loamy sand
				  soil textural classes and shall be considered SUITABLE with respect to
				  texture.
(B) SOIL GROUP II - COARSE
				  LOAMY TEXTURE SOILS. The coarse loamy group includes sandy loam and loam soil
				  textural classes and shall be considered SUITABLE with respect to
				  texture.
(C) SOIL GROUP III - FINE
				  LOAMY TEXTURE SOILS. The fine loamy group includes silt, silt loam, sandy clay
				  loam, clay loam, and silty clay loam textural classes and shall be considered
				  PROVISIONALLY SUITABLE with respect to texture.
(D) SOIL GROUP IV - CLAYEY TEXTURE SOILS. The
				  clayey group includes sandy clay, silty clay, and clay textural classes and
				  shall be considered PROVISIONALLY SUITABLE with respect to texture.
(E) The soil textural class shall be
				  determined in the field by hand texturing samples of each soil horizon in the
				  soil profile using the following criteria:
(i) Sand: Sand has a gritty feel, does not
				  stain the fingers, and does not form a ribbon or ball when wet or
				  moist.
(ii) Loamy Sand: Loamy sand
				  has a gritty feel, stains the fingers (silt and clay), forms a weak ball, and
				  cannot be handled without breaking.
(iii) Sandy Loam: Sandy loam has a gritty
				  feel and forms a ball that can be picked up with the fingers and handled with
				  care without breaking.
(iv) Loam:
				  Loam may have a slightly gritty feel but does not show a fingerprint and forms
				  only short ribbons of from 0.25 inch to 0.50 inch in length. Loam will form a
				  ball that can be handled without breaking.
(v) Silt Loam: Silt loam has a floury feel
				  when moist and will show a fingerprint but will not ribbon and forms only a
				  weak ball.
(vi) Silt: Silt has a
				  floury feel when moist and sticky when wet but will not ribbon and forms a ball
				  that will tolerate some handling.
(vii) Sandy Clay Loam: Sandy clay loam has a
				  gritty feel but contains enough clay to form a firm ball and may ribbon to form
				  0.75-inch to one-inch long pieces.
(viii) Silty Clay Loam: Silty clay loam is
				  sticky when moist and will ribbon from one to two inches. Rubbing silty clay
				  loam with the thumbnail produces a moderate sheen. Silty clay loam produces a
				  distinct fingerprint.
(ix) Clay
				  Loam: Clay loam is sticky when moist. Clay loam forms a thin ribbon of one to
				  two inches in length and produces a slight sheen when rubbed with the
				  thumbnail. Clay loam produces a nondistinct fingerprint.
(x) Sandy Clay: Sandy clay is plastic,
				  gritty, and sticky when moist and forms a firm ball and produces a thin ribbon
				  to over two inches in length.
(xi)
				  Silty Clay: Silty clay is both plastic and sticky when moist and lacks any
				  gritty feeling. Silty clay forms a firm ball and readily ribbons to over two
				  inches in length.
(xii) Clay: Clay
				  is both sticky and plastic when moist, produces a thin ribbon over two inches
				  in length, produces a high sheen when rubbed with the thumbnail, and forms a
				  strong ball resistant to breaking.
(F) The Department may substitute laboratory
				  determination of the soil textural class as defined in these Rules by
				  particle-size analysis of the fine-earth fraction (less than 2.0 mm in size)
				  using the sand, silt, and clay particle sizes as defined in these Rules for
				  field testing when conducted in accordance with ASTM (American Society for
				  Testing and Materials) D-422 procedures for sieve and hydrometer analyses which
				  are hereby adopted by reference in accordance with
				  G.S.
				  150B-14(c). For fine loamy
				  and clayey soils (Groups III and IV), the dispersion time shall be increased to
				  12 hours. Copies may be inspected in and copies obtained from the Department of
				  Environment, Health, and Natural Resources, Division of Environmental Health,
				  P.O. Box 27687, Raleigh, North Carolina 27611-7687.