Rating and Qualification Certificates Dam Construction: Grades A and B Dam Construction Project Management: Grade A Irrigation and Drainage Networks: Grades A and B Irrigation and Drainage Network Project Management: Grade A Certification of Operation and Maintenance of Irrigation and Drainage Networks Water and Wastewater Facilities: Grade A Structures: Grade C Certification of competence in the operation, maintenance and safety control of dams Certificate of competence in the operation and maintenance of irrigation and drainage networks Certification of competence in the operation and Maintenance of Wastewater Treatment Plants Certificate of Competence of Companies for Operation and Maintenance of Drinking Water Facilities (Drinking Water Treatment Plant) Certificate of Competence of Companies for Operation and Maintenance of Drinking Water Facilities (Production, transmission and distribution) Environment: Grade C