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Solar Energy Project Phases and Activities

Impacts from a solar energy project can result from activities that occur during each phase of the project: site evaluation, construction, operation and maintenance, and decommissioning and reclamation.

What Activities Occur During the Site Evaluation Phase?

Prior to construction, a detailed land survey would be performed to establish local benchmarks and project site boundaries. Activities would include surface hydrology and floodplain mapping, and ecological studies. Additionally, a topographic survey would be performed in order to establish site grading and drainage plans and to determine the placement of solar collectors, access roads, rights-of-way (ROWs), and other project components.

A geotechnical survey would evaluate general surface conditions, subsurface conditions, seismicity, and other geological information required to develop recommendations for the design and construction of project components (e.g., type of foundations required to support the solar collectors). The geotechnical survey would require soil borings. More extensive deep corings could be required for structures that would require substantial foundations (e.g., power towers).

On-site monitoring/sampling wells and associated impoundments for well drilling fluids and cuttings may be required if groundwater resources would be used to meet water requirements.

Before a solar development can be planned and built, the solar regime at a potential site must be precisely characterized. Solar monitoring equipment, including solar sensors and a meteorological tower, should be installed to collect data on direct normal insolation and weather conditions such as dust and haze, temperature, humidity, precipitation, clouds, and fog. Additionally, satellite measurements are an important source for solar insolation data.

It is possible that site characterization activities requiring more extensive impacts could be delayed until the construction phase.

What Activities Occur During the Construction Phase?

The entire solar project area could be impacted by site preparation activities such as clearing and grading; construction of access and on-site roads; preparation and use of material and equipment laydown areas; placement of solar collectors; construction of the electrical substation, central control facility and ancillary facilities; and installation of power and signal cables (typically buried or vaulted).

Concrete ingredients (sand, aggregate) may need to be extracted and hauled to the site.

A refueling station (with diesel and gas storage tanks) would be used during construction.

Construction of a transmission line and possibly, a substation would be required.

A gas pipeline may need to be constructed for parabolic trough, compact linear Fresnel reflectors, and power tower solar developments. Water pipelines may also need to be constructed unless on-site wells are drilled to obtain the water that will be needed for plant operation and maintenance.

What Activities Occur During the Operation and Maintenance Phase?

Minimal land-disturbing activities and associated impacts are anticipated during the operation phase. Routine activities would include operation of the solar facility to produce power, and regular monitoring and maintenance activities to ensure safe and consistent operation.

Mirror washing would be required routinely (e.g., every few weeks). In most cases, mirror washing would occur during evening hours.

Both on- and off-site maintenance of access roads may be required after rainfall events (e.g., blading and sediment removal from culverts).

Vegetation maintenance would be required within the solar collector field and within the transmission line, gas pipeline, and water pipeline ROWs.

What Activities Occur During the Decommissioning and Reclamation Phase?

Decommissioning of a solar energy project could range from mothballing to full removal of equipment and facilities. A decommissioning plan would need to be prepared and approved prior to the actual decommissioning of the project.

Underground components would be removed to a depth of at least three feet to ensure an unobstructed root zone for revegetation. More deeply buried components might be abandoned in place.

Following removal of site components, site reclamation and revegetation would mitigate some impacts, such as soil erosion, habitat fragmentation, and visual impacts.