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South Coast Technology Center Project
<br />CEQA Exemption 15183
<br />Project Site was deemed low to moderate and the risk for lateral spread was determined to be
<br />low. Additionally, based on the laboratory test results and a visual classification of the on -site
<br />soils, the expansion potential of the soils vary from very low to medium; however, clayey soils
<br />onsite may have a high expansion potential. Consistent with the GPU PER, implementation of
<br />RR G-1 and RR G-2 would reduce impacts related to liquefaction, soil expansion, collapse, and
<br />subsidence to less than significant levels. Moreover, the proposed Project would be constructed
<br />based on the recommendations of the Geotechnical Design Report. Based on the above analysis,
<br />and consistent with the GPU PEIR, with compliance with existing regulations, the Project's
<br />impacts related to rupture of a known earthquake fault, strong seismic ground shaking, seismic -
<br />related ground failure (including liquefaction), landslides, lateral spreading, subsidence, and
<br />collapse would be less than significant. As such, no new project -specific mitigation measures are
<br />required.
<br />Construction of the proposed Project would involve ground -disturbing activities that could result
<br />in erosion. As further discussed in Section 4.10, Hydrology and Water Quality, the proposed
<br />Project would comply with regulatory requirements, such as the Construction General Permit and
<br />implementation of a Water Quality Management Plan, during construction and operation, which
<br />would reduce the potential for erosion to occur. Consistent with the General Plan, compliance
<br />with existing regulations including implementation of regulatory requirements would ensure the
<br />proposed Project would not result in a significant impact related to erosion. No new or substantially
<br />more severe impacts would occur compared to the determinations of the GPU PER, and no new
<br />project -specific mitigation measures are required.
<br />In compliance with RR G-3, construction and operation of the proposed Project would not involve
<br />the use of septic tanks or alternative wastewater disposal systems. As such, compliance with
<br />existing regulatory requirements would ensure no impact related to the use of such systems would
<br />occur.
<br />With regards to paleontological resources, in compliance GPU PER MM GEO-2, consultation
<br />with a paleontologist confirmed that project -related grading could occur at depths that could
<br />encounter highly sensitive sediments for paleontological resources. Based on the Cultural
<br />Memorandum, geologic units underlying the Project area have been mapped as Holocene alluvial
<br />deposits (Qal), late Holocene to late Pleistocene -age young Quaternary deposits (Qya), Holocene
<br />to late Pleistocene -age young axial -channel deposits (Qya,,), and Holocene to late Pleistocene -
<br />age young alluvial deposits (Qya). Deposits from the Holocene epoch (less than 11,700 years
<br />ago) can contain remains of animals and plants; however, only those from the middle to early
<br />Holocene (older than about 5,000 radiocarbon years) are considered scientifically important or
<br />significant. Holocene -age deposits may overlie older alluvium of Pleistocene age at unknown but
<br />potentially shallow depths. Pleistocene -age alluvial deposits are also potentially present in the
<br />Project area and have yielded scientifically important fossils elsewhere in the region, including
<br />horses, camels, reptiles, birds, marine mammals, and fish at various depths below current ground
<br />surface. Moreover, based on a records search of the Natural History Museum of Los Angeles
<br />County and a supplemental investigation of online sources, 13 fossil localities were identified
<br />within five miles of the Project Site. Thus, while the Holocene -age deposits in the Project area
<br />have low sensitivity, Pleistocene -age alluvial sediments may underlie these younger sediments
<br />at a relatively shallow depth. The records search results indicate that potentially fossil -baring units
<br />may underlie the Project area, since Pleistocene -age deposits outside of the Project area have
<br />contained fossils. Therefore, sediments in the Project area are considered to have paleontological
<br />sensitivity increasing with depth, or low -to -high sensitivity, suggesting that project -related ground -
<br />disturbing activities have the potential to destroy or otherwise adversely impact significant
<br />paleontological resources below young Holocene -age soils at unknown depths within the Project
<br />July 2024 Page 48
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