13-132-030 Classification of subsurface materials.

   Insofar as practicable, the following terms shall be used in the description and classification of sub-surface materials:

   (a)   Solid Rock. Sound, unweathered limestone without visible voids, known to have a thickness of at least eight feet;

   (b)   Soft Rock. Weathered or porous limestone, rock containing fissures, shale or other rock material not included under (a);

   (c)   Boulders. Rounded to angular rock fragments having a least dimension not less than eight inches;

   (d)   Gravel. Cohesionless aggregate of rounded to angular rock fragments ranging in size from one-quarter inch to eight inches;

   (e)   Sand. Cohesionless aggregate of rock fragments or grains ranging in size from 0.06 mm. to one-quarter inch. Deposits of sand shall be described as loose or compact;

   (f)   Inorganic Silt. Cohesionless aggregate of grains ranging in size from 0.002 mm. to 0.66 mm. Aggregate is non-plastic and consists of grains not distinguishable by the naked eye. Deposits of inorganic silt shall be described as loose or compact. A lump of the air-dried material has very little resistance to crushing;

   (g)   Clay. Cohesive soil, plastic within wide range of water content. The consistency of a clay shall be defined by the strength of a fairly undisturbed cylinder whose length is from 1.5 to 2 times its diameter, as follows:

 

Consistency	Unconfined Compressive Strength – Tons per Square Foot
Very soft	less than 0.35
Soft	0.35 to 0.59
Stiff	0.60 to 0.99
Tough	1.0 to 1.9
Very tough	2.0 to 3.9
Hard	4.0 to 7.9

 

   (h)   Hardpan. Cohesive or cemented material that offers great resistance to hand excavating tools.

   (i)   Organic Soil. Soil containing significant percentage of partly or wholly decomposed organic matter. According to the character of the constituents, the terms organic clay, organic silt or peat shall be used.

(Prior code § 70-2.1)