design engineers to identify appropriate construction plan, operation and mitigation measures. An environmental impact report or statement is completed before the design of any project begins in earnest, and mitigation action plans—as needed—will be part of submitted planned contract bid packages. Project delivery that includes mitigation measures is a means to assure environmental protection.

Groundwater hydrology engineers address challenges associated with protecting groundwater as a resource, and with engineering in consideration of groundwater as a component of the soil and rock. The control of groundwater, commonly encountered during underground construction, is a complicated and potentially costly physical challenge. It is important that groundwater conditions at infrastructure works shafts and surface penetrations are mapped and analyzed, and that groundwater preservation and management solutions are developed and coordinated with all team members. Groundwater conditions can influence a series of fundamental decisions related to construction and operation, including choice of ground excavation methods, support systems, and of water barriers that may be required to protect groundwater resources and maintain a “dry” underground facility.

Facility Construction

Once construction begins, structural engineers lead units charged with the design of specific project sections or elements (normally what becomes a construction contract package). These engineers know how appropriate connections between the different structural components are made, and may have to incorporate seismic design and waterproofing concepts into underground structures to make structures safe for given circumstances. Seismic engineers evaluate for and prepare site-specific seismic designs criteria to assure compliance with existing codes and safety. Geotechnical engineers, TBM specialists, and mining engineers may be enlisted as part of the team to allow safe excavation of materials from within the earth.

Building underground facilities, as with many aboveground facilities, requires the expertise of underground works construction engineers who understand problems associated with crowded work sites and difficult logistical considerations. Work sequences can become disordered by small events that result in delays and added costs. A seasoned construction engineer performs full constructability reviews to anticipate such problems as the designs develop.

Mechanical, Electrical, and Communication Systems

Trained mechanical engineers design, construct, and operate, multiple mechanical systems needed in underground projects, including water management (e.g., sumps and piping, valves, pumps and motors, and controls), and heating, air conditioning, and ventilation systems. Mechanical equipment needs

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