Unexpected Playa Geohazards Create Issues for Solar Facility-PPT Presentation

PPT Presentation

Pdf Summary

A 100-MW solar facility built on a dry lakebed in 2016 experienced recurring ground fissures that damaged panels and support structures, restricted access, and created safety concerns. Initial geotechnical studies found no fissures or nearby faults and identified no major groundwater withdrawal.<br /><br />Fissures first appeared after rainfall in 2016 and were backfilled with controlled low-strength material (CLSM). A larger event in 2017 produced a fissure extending about 1,200 feet beneath the solar arrays, with depths reaching 11 feet. In August 2022, a third major fissure extended roughly 2,500 feet, reached depths greater than 20 feet in places, and included visible voids.<br /><br />Investigators reviewed historical records and imagery, conducted field studies, and used multi-channel analysis of surface waves (MASW). The geophysical surveys identified vertically oriented low-velocity anomalies near fissures. The presentation attributes fissure development to internal erosion, potentially associated with buried paleochannels or basin-wide settlement and shrinkage. Surface water—particularly runoff entering the site—was identified as a key trigger and driver of fissure growth.<br /><br />Hydraulic modeling of rainfall scenarios informed drainage improvements to control run-on from the west. Proposed channels incorporated into access roads were designed to manage surface flows. To restore access, improve safety, and support affected structures, fissures were backfilled using a combination of slurry and granular material, placed with pumpers and tremie methods.<br /><br />The case shows how previously undocumented playa geohazards can emerge over time and affect infrastructure, requiring both subsurface investigation and surface-water management.

Keywords

solar facility

dry lakebed

ground fissures

internal erosion

surface runoff

MASW survey

playa geohazard

backfilling

drainage improvement

groundwater withdrawal