VAFB-2001-02: Archaeological Testing in Firebreaks and Access Roads on Vandenberg Air Force Base Santa Barbara County, California

Summary

This document is a Section 110 report supporting the development of a Fire Compartmentalization Plan to guide fire protection and suppression activities relative to cultural resources in conjunction with the Integrated Cultural Resources Management Plan (ICRMP), Vandenberg Air Force Base (VAFB).

The base maintains a comprehensive system of firebreaks and access roads, and a number of known archaeological sites are intersected by elements of that system. Many of these firebreaks and access roads are paved; thus, continued use and maintenance poses no threat to site integrity. However, continued firebreak and access road maintenance elsewhere could be impacting site integrity.

Eighty-eight archaeological sites crossed by firebreaks and access roads were examined to help develop recommendations for continued maintenance. The work was completed in two stages. During Stage I, recommendations were derived where possible by surface examination of the local soils and geomorphology at firebreaks and access roads crossing each site. During Stage II, limited subsurface probing was used to gather additional information at 21 sites to develop recommendations for continued maintenance. This work was completed by Applied EarthWorks, Inc. (Æ) under subcontract to Tetra Tech, Inc. as part of Task Assignment 445 under the Wing Environmental Services Contract (F04684-95-C-0045).

Æ’s inspections revealed that the maintained surfaces of firebreaks and access roads intersecting archaeological sites can be divided into five groups based on geologic substrata and similarities in conditions that contribute to erosion and, subsequently, to the type and frequency of maintenance activities. Some firebreak and access road surfaces lie directly on weathered bedrock. These surfaces are highly susceptible to water erosion. A second group of access roads and firebreaks are on a substrate of weakly indurated sandstone or cemented sandy soils; these access roads and firebreaks are also highly susceptible to water erosion. A third group of fire protection elements, which are typically maintained by disking, are in loosely consolidated or unconsolidated dune deposits. Wind erosion is most common in these firebreaks and access roads, although some water erosion is evident. The fourth type of geologic substrate is primarily evident along Coast Road on South Base, where firebreaks and access roads lie on the native surface and construction has been limited. Most erosion in this area is at stream crossings. Road surfaces away from streams exhibit limited erosion because road construction generally followed the slope contour. The final substrate group includes access roads and firebreaks that are paved, graveled, or chip sealed. These are stable surfaces subject to minimal erosion.

Between one and four shovel probes were manually excavated in each of 21 archaeological sites where the surface examination was insufficient to develop recommendations for continued firebreak and access road maintenance. Sites were selected for subsurface probing primarily to characterize roadbed fill and thickness and to investigate the effects of traffic and maintenance on intact cultural deposits underlying road fill. Many of the selected sites are located along Coast Road on south Vandenberg AFB, where it was often difficult to determine by surface inspection if the road was built on imported fill or the native surface.

Specific recommendations for firebreak and access road maintenance at each site are presented in Chapter 5. Recommendations are based on the type of substrata and associated stability. Continued and regular maintenance of firebreaks and access roads was assumed when recommendations were developed, as fire protection elements will become unstable and subject to more severe erosion if maintenance is discontinued.

This Resource is Part of the Following Collections

• Vandenberg Space Force Base (VSFB) - Cultural Resource Report

Keywords

Spatial Coverage

Record Identifiers

VAFB Document Number(s): VAFB-2001-02

File Information