This document is a Section 106 historic property inventory report and assessment of effects for the Phantom Space SLC-5 Orbital Launch Site Project. The proposed Phantom Space SLC-5 OLS Project (hereafter “Project”) would include the construction of a new space launch complex designated as SLC-5. The new SLC-5 will include two, 1,500 square feet concrete launch pads (designated SLC-5 East and SLC-5 West), an assembly facility, refurbishment facility, payload processing facility, launch and mission control center, customer support facility, and storage for ground support equipment. The new launch complex will require dedicated utilities such as electric circuits, communication, and water lines, and a fence line and fire breaks will be constructed around the perimeter. Altogether, the project components (launch site, utility corridor, roads, firebreaks, and vegetation management areas) total 21 acres. The report delineates the project area of direct impact (ADI) and the project area of potential effect (APE). It also discusses a study of noise vibration and sonic booms associated with the proposed launches at SLC-5. The noise study resulted in an APE that is defined by a 120 dB contour and is discussed in detail in Appendix A of the document. The report reads that no prehistoric rock art, rock cairns, rock shelters, or structures constructed of rock, wood, glass block, or adobe, which could be affected by launch noise vibrations were identified within the polygon of the noise vibration study. Only one historic-age built-environment resource, the Union Pacific Railroad’s Honda trestle, is situated within the 120 dB noise vibration contour. This steel structure, constructed to withstand strong vibrations and concussive forces, has no potential to be affected by noise vibrations, and therefore, it is excluded from the APE. The report also considered the Juan Bautista de Anza National Historic Trail. This resource is mapped as intersecting the launch noise contour, along the coast approximately 2,000 feet to the west of the proposed launch pads. There is no physical manifestation of the former Anza Trail route anywhere near this location, and therefore, this portion of the Anza Trail is only eligible for the NRHP in concept. This project has no potential to impede the public’s perception of the route that Anza followed along the coast in the vicinity of the Project. Furthermore, the construction and use of SLC-5 would not introduce any visual or auditory elements which would have the potential to cause effects to this historic property under 36 CFR 800.3(a)(1); therefore, the Anza Trail was considered in this study, but it has been excluded from the APE because it has no potential to be affected. Applied EarthWorks completed surface and subsurface survey (presence/absence testing) within the ADI to assess whether unknown buried archaeological deposits were present. A total of 92 STPs were excavated during the project. Eighty STPs were excavated within the ADI, and 12 additional STPs were excavated outside the ADI to investigate isolated artifacts; none of these isolated artifacts became sites that extend into the APE, so they were excluded from further consideration. No cultural materials was encountered during excavation of any of the STPs.
Josh Smallwood (2022) studied this question.