Item 28 - Public Hearing - ZOA No. 20204-01 South Coast Technology Center

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South Coast Technology Center Project CEQA Exemption 15183 Based on the Cultural Memorandum, the Project Site does not contain any historical resources as defined by CEQA Guidelines Section 15064.5(a). Three buildings would be demolished as part of the proposed Project, but they are not historic in age (i.e., 50 years old). As discussed in the Cultural Memorandum, aerial photographs indicate that the two buildings on the Project Site east of Susan Street were constructed between 1980 and 1987. The third building was constructed between 1987 and 1992. Thus, no impacts would occur with regards to historical resources. A records search of the Project Site and a half -mile search radius identified five resources within the Project area, none of which are located within or adjacent to the Project Site. An archaeological field survey conducted in February 2024 identified two marine shell scatters along the northeast of the Project Site's vacant parcel; none of the shell observed on -site showed any sign of burning or other cultural modification. No prehistoric artifacts were observed, either within or outside the shell scatters anywhere on the Project Site. Based on the results of the field survey, a follow-up visit occurred to conduct limited subsurface testing to understand the origin of the shell scatters and determine whether the shell is an archaeological resource. Based on the collective evidence from the geotechnical trenching and the archaeological shovel test pits, it was concluded that the shell scatters do not constitute an archaeological site. All the observed shell and shell fragments are unmodified. All the documented shell and shell fragments were located at or within 10 cm of the surface, within artificial fill. No prehistoric artifacts were observed anywhere in the Project Site. The collective evidence is that the shells and shell fragments were brought in with imported fill and dumped at the site relatively recently. Thus, the shell scatters are not part of a prehistoric deposit and are not historical resources as defined by CEQA Section 15064.5(a). The Project would redevelop a 10.2-acre office park and develop an approximately 5.6-acre vacant field. Construction activities would include excavation and grading, which could disturb unknown archaeological resources. The majority of the excavation for the proposed buildings would require over -excavation for the building pads at a depth of approximately 5 to 8 feet. Trenches for utility connections would require a maximum excavation depth of 14 feet. Based on the Cultural Memorandum, sensitivity for cultural resources consisting of archaeological sites is considered low at and near the surface, but increases to moderate with depth. Geologic and soils maps indicate that the Project area contains surficial deposits of younger Quaternary alluvial sediments. These sediments have the potential to contain buried archaeological deposits. The late nineteenth to early twentieth century bed of the Santa Ana River was located approximately 0.6 miles to the northwest and would have provided abundant resources to area inhabitants. As the river meandered and changed its course, it or its tributaries may have been located closer to the Project area at times. These conditions heighten the sensitivity of the Project area for buried cultural resources. However, the Project area has an extensive history of recent disturbances. East of Susan Street, the Project Site is entirely developed by the construction of multi -storied office buildings, a pond, and parking lots. Building methods at the time, and the installation of associated utilities, would have resulted in the disturbance of archaeological sites buried at shallow depths. West of Susan Street, geotechnical testing indicates that a layer of imported fill, ranging from 3 to 4.5 feet thick, covers the entire Project Site. Nevertheless, buried resources may remain in areas where developments such as parking lots or structures with shallow foundations have required only minimal ground disturbance, or below the existing imported fill. Therefore, the sensitivity of the Project area at the surface and near surface is low due to past disturbances. However, excavations for the Project are anticipated to disturb a large part of the Project Site to points below the level of existing artificial fill and other disturbances and the sensitivity for potential buried prehistoric archaeological sites is moderate in these undisturbed soils. Therefore, consistent with the GPU PEIR, the proposed Project would implement GPU PEIR MM CUL-7 which would require July 2024 Page 38