Electrical Contractor (C-13) Boiler, Hot-Water Heating & Steam Fitting Contractors (C-4) Fire Protection Contractor (C-20) Sewer, Sewage Disposal, Drain, & Pipe Laying Contractor (C-43) Refrigeration Contractor (C-40) Plumbing Contractor (C-37) Subcontractors Well Contractor (C-57) Welding Contractor (C-56) Water Chlorination & Sanitation Contractor (C-37d) Ventilating & Air Conditioning Contractor (C-52)

Cement Concrete Contractor (C-31a) Asphalt Paving & Surfacing Contractor (C-3) Aluminum & other Metal Shingles Contractor (C-42a) Irrigation & Lawn Sprinkler Contractor (C-37b) Institutional & Commercial Equipment Contractor (C-25) Injection Well Contractor (C-57b) General Engineering, General Building & Specialty Contractors (ABC) General Engineering & Specialty Contractors (AC) Excavating, Grading & Trenching Contractor (C-17) Sewer, Sewage Disposal, Drain, & Pipe Laying Contractor (C-43) Post Tensioning Contractor (C-38) Ornamental, Guardrail, & Fencing Contractor (C-32) Masonry Contractor (C-31) Well Contractor (C-57) Welding Contractor (C-56) Swimming Pool Contractor (C-49) General Contractors

Classified Specialist (C-68) Geothermal Well & Exploratory Drilling Pumps Installation Contractor (C-57a) Pump Supplier Subcontractors Well Contractor (C-57) Water Works