This chapter shall not be construed to prevent or affect:

1. (a) The work of an employee or subordinate of a person holding a certificate of registration under this chapter or an employee of a person practicing lawfully under subsection (a) of this section, provided such work does not include final soil classifying decisions and is done under the direct supervision of and verified by a person holding a certificate of registration under this chapter or a person practicing lawfully under subsection (a) of this section.
2. (b) The practice of any other legally recognized profession or trade.
3. (c) The practice of soil classifying by a person who is regularly employed to perform soil classifying services solely for his employer or for a subsidiary or affiliated corporation of his employer, providing the soil classifying is performed on the real property of his employer.