This sub-class includes environment engineering design and/or consultancy services such as: •water supply and/or treatment systems •waste treatment systems (e.g., sewer systems, sewage treatment plants) •erosion control systems •wastewater treatment and/or disposal systems •waste management systems (e.g., recycling facilities, landfill sites) Units in this sub-class are primarily engaged in: •environmental engineering design (i.e., applying physical laws and/or principles of engineering in the engineering project). Other services related to the engineering project may be provided as well, for example: provision of advice regarding engineering principles and/or methods, preparation of feasibility studies, preparation of preliminary and/or final plans and designs, provision of technical services during the construction or installation phase, inspection and/or evaluation of the project. •environmental engineering technical consultancy services (i.e., provision of advice to clients regarding engineering principles and/or methods) •environmental engineering project development and/or management, which may include procurement, construction and installation services