4.14.1 REGIONAL SETTING

The cultural resources setting for the region varies because of differences in landform and prehistoric/historic land use. As discussed in the narratives for the various power plants, the level of archaeological and historical studies that have been completed for the plants and the surrounding environment ranges from extensive studies to no field surveys. Overall, the cultural resource setting includes prehistoric sites that may extend back for several thousand years; some sites show evidence of contact with early European cultures. The historic sites reflect the broad cultural panorama of this region of California. Historic sites in the region include those associated with early exploration; the Spanish, Mexican, and American expansions; the Gold Rush; the boom of the 1880–1890s; post-1900 industrialization; and the growth of the region within the World War I, World War II, and post-war eras. The three sub-settings within the region include the San Francisco Bay area, the Sacramento River and San Francisco Bay setting, and, for the Geysers, the inland valley and hills.

4.14.2 LOCAL SETTING

Commercial operations of the existing Potrero Power Plant units first began in 1965, although the first unit, Station A, now long decommissioned, was first constructed in 1901. The western segment of the Potrero Power Plant is generally situated beyond the native Bay margins and was constructed on fill soils. The subsurface soil is Bay Mud, which is a plastic clay/silt that is saturated and unconsolidated. As is common along the Bay margins, the muds are frequently interlaced with Holocene alluvial deposits along the historic margins of the Bay. While it is uncertain when filling and landform alteration began, some fill was placed as early as the 1860-1870 period.

The following discussion of prehistoric and historic resources within the Potrero plant area is based on work completed for Potrero Unit 7 (Wirth, 1979). More recent information on the surrounding area is provided by Hupman and Chavez (1995) in their report for the San Francisco Waterfront Plan EIR. The potential for prehistoric resources within the project area is low to moderate, based on the possibility that rising sea levels during the last glacial period may have submerged sites, and given the placement of fill over native Bay margins. A field reconnaissance conducted on March 19, 1998 did not identify any prehistoric resources.

The findings of the Wirth (1979) study indicate that the Potrero facility had at least moderate and possibly high potential for buried historical resources. Reportedly, a Chinese fishing village may have been established in this area in the early 1850s. The placement of the village is not clearly documented, although at least one historian places it in the vicinity of the project (Schwendinger, 1984). The area historically known as Potrero Point witnessed its first clearly documented settlement and use when two powder magazines were built there in 1854-1855. Following the Civil War in 1866, the Pacific Union Rolling Mills constructed its main foundry at the foot of 20th Street, approximately three blocks from the plant site. In response to an increased demand, the Union Iron Works took over the facility and further improved it in 1883. In the decades between the 1880s and the early 1900s, the Potrero Point region burgeoned into an industrial district. Shipyards joined the metal works, and the industrial activities focused on metal manufacturing and fabrication, shipbuilding, and ship repairs.

Located within the project site, the Station A power plant is an abandoned, standing brick structure. This is an unreinforced masonry building and is located south of fuel storage tank No. 3-4 between Humboldt Street and 23rd Street. Station A was constructed in 1901 and is an excellent example of turn-of-the-century industrial architecture. Its brick work and massiveness contribute to its architectural value. This building has not been assessed for National Register status, although it would most likely qualify for nomination for listing on the National Register at the local and state level under Criteria A and C. Because of the potential life safety hazard from response to a strong earthquake, San Francisco enacted the San Francisco Unreinforced Masonry Building ordinance. The Station A power plant is subject to that ordinance, which requires owners of unreinforced masonry building that do not meet certain structural standards to cause the building to be retrofitted or demolished. PG&E has received a waiver from the City and County of San Francisco that allows PG&E until 2006 to comply with the ordinance.

The historic Spreckels Sugar House, which was built in 1915, was demolished in 1995. Remnants of associated brick work and appurtenances can be seen between Station A and the plant maintenance and storage area within the plant site.

Previous studies conducted on the Potrero plant site as part of investigations for Potrero Unit 7 provided a thorough review of the literature for the project site, although the study did not cover the precise footprint for the proposed divestiture site.

Commercial operations of the existing Contra Costa Power Plant units began in 1953. The project area is situated on the margins of the San Joaquin River in an area that has been subjected to periodic flooding. The soil type along the river terraces and margins is a fine- to medium-grained sand that is loosely compacted. In addition to the native soils, portions of the project site have been subjected to fill.

The subject property is situated in a setting known to contain prehistoric resources. The river margins, as well as the marshlands and sloughs of the area, were prime settings for prehistoric occupation and use. Previous studies in the immediate vicinity have not identified prehistoric resources, possibly reflecting the non-native landforms that have resulted from fill and dredging. A field reconnaissance performed on March 20, 1998 focused on the plant site and the area to be divested. No prehistoric resources were noted.

As indicated by generalized settlement patterns and regional studies, there should be a relatively high potential for resources within the project area. However, in a previous study of five acres within the plant site adjacent to Wilbur Street and the paved access road, no resources were encountered. Given the results of that study and previous disturbances in the project area, there is moderate to low potential for buried prehistoric resources under the areas filled in the past.

A review of the historical literature for the area indicated that the only known, recorded historic site in the general area is the Marsh Landing Site. The landing site is situated approximately 1,000 feet east of the northeastern corner of the project site. The landing was built in 1853 by one of California’s pioneers, John Marsh. The site consisted of a smokehouse, a wharf, a blacksmith shop, and a warehouse. The landing served as a major point of departure for produce and supplies bound for San Francisco.

The Marsh Landing Site has not been formally assessed for National Register eligibility; however, it is listed on the California Inventory of Historic Resources, the Office of Historic Preservation’s Historic Properties Directory, and on the Contra Costa County Preliminary Historic Resources Inventory. At present, the Marsh Landing Site is recorded on the basis of literature and early maps, not on the discovery or recordation of physical remains. A potential for buried historic resources exists, especially in the northeastern corner of the project site. While no standing historic buildings, structures, or objects were noted within the project site during previous studies or as a part of the current one, no assessment of buildings or structures on adjacent properties has occurred.

Since the Contra Costa Power Plant is more than 45 years old (1) and currently is in operation as a power plant, it does possess some historical value. However, the technology associated with the Contra Costa Power Plant is not unique or innovative, and its historical value is limited in the context of this type of industrial or utility-related facility. Therefore, although no formal determination has been made, it is not likely that the power plant could be eligible for listing on the National Register of Historic Places or the California Register of Historical Resources.

No known historical structures and facilities are located within the immediate vicinity of the Contra Costa Power Plant.

A field reconnaissance that was performed on March 20, 1998 did not locate any standing historic resources and did not indicate the potential for buried resources within the project area.

Commercial operations at the Pittsburg Power Plant first began in 1954. The Pittsburg Power Plant was constructed on fill imported from other areas. The project site itself was historically a slough that was part of the larger Honker Bay land feature. As is typical of the area, the underlying soils consist of Bay Muds. Bay Muds are unconsolidated, plastic clay/silts that are rich in organic materials and tend to be saturated. When the project site was actually reclaimed or filled is uncertain, although it was after 1870 and probably around the turn of the century (post-1900).

Previous studies have not indicated the presence of any prehistoric sites or resources in the immediate area of the project site. Stewart (1982) provides an overview to the region, including a valuable discussion of the potential for buried and submerged sites. Resources recorded in adjacent areas indicate that the pattern for site occurrences reflects occupation and use of the margins of Honker Bay. As with many other landforms along the Bay, there is a potential that prehistoric sites were submerged during the rise in sea levels following the last glacial period, and that such sites are currently under water or on land masses that were under water and have been filled/reclaimed. A field reconnaissance was conducted on March 20, 1998. The field examination focused on investigating those areas that were not obscured by asphalt or concrete and where open ground could be viewed. Particular emphasis was placed on the area south of the Unit 7 cooling water canal because it had the most potential for native, or natural, ground surfaces. The field investigation verified the historic record, which indicated that fill and dredge soils had been placed throughout this area. If prehistoric resources did once exist in this area, they would be covered by several feet of fill and dredge spoils.

Previous research, coupled with the current field investigation, indicate that there are no standing historic buildings, structures, or objects within the project site. Further, there is no potential for subsurface historic archaeological resources. The nearest recorded historic resource is the Congregational Church at the corner of West 4th Street and Montezuma Street, approximately six blocks from the power plant. The church was originally constructed in 1882 in Nortonville to serve the resident coal miners and was subsequently moved in 1894 to its present site. The church has been evaluated for nomination to the National Register and determined to be eligible as a local, rather than a state or national resource.

Since the Pittsburg Power Plant is not 45 years old, it is inappropriate to determine whether the property would be eligible for listing on the National Register of Historic Places or the California Register of Historical Resources.

Commercial operations at the Geysers Power Plant first began in about 1971. The Geysers plant is situated within an area historically known as the Geysers within the Mayacmas Mountains in Sonoma and Lake Counties. The plant is located 27 miles northeast of Healdsburg, California. Elevations vary from 2,500 to more than 4,500 feet above mean sea level in the area. The area is well drained and contains several rivers and creeks, including Anderson Creek, Bear Canyon Creek, Big Sulphur Creek, Hot Springs Creek, Little Sulphur Creek, and Squaw Creek. The geology of the area consists of underlying rocks of the Mesozoic Franciscan Formation. This formation is comprised of shale, graywacke, altered basalt, and chert. There is also serpentinized periodotite and shist.

Several archaeological and historical studies have been conducted in the Geysers area. With the exception of Unit 16, all of the Geysers units were within the boundaries of a large-scale survey conducted by David Fredrickson in 1974 (1974a; 1974b). During the same survey, although the Unit 16 site was not surveyed, a literature search revealed one or more sites had been previously identified within one-quarter mile of the site. Units 1, 2, 3, 4, 5, 6, 7, 8, 12, 13, 14, 16 and 18 all have recorded one or more archaeological sites adjacent to, or within, a one-quarter-mile radius of each of the units. In general, the recorded sites represent the activities of the Wapo Indians, who camped at the lower elevations and used fumaroles and hot waters for curative and medicinal purposes and quarried the locally available cherts and basalts. The greatest potential for prehistoric and historic period Wapo sites is in the lower elevations, near water sources.

Units 9, 10, 11, 15 and 17 do not have any prehistoric sites recorded within a one-quarter-mile radius of any of the units.

A review of historic directories and landmarks lists, coupled with a field survey conducted on March 18, 1998, indicated that there are no known historic resources within the various plant sites at the Geysers. The historic Geysers Resort Hotel, which was located near the Unocal Gate No. 1, was demolished in 1980. This site had been used as a resting spot, resort, and access point to the Geysers for more than one hundred years. Remnants of other historic activities associated with the resort and with early geothermal development may exist in the area, but none were noted in the project area.

Since the Geysers Power Plant is not 45 years old, it is inappropriate to determine whether the property would be eligible for listing on the National Register of Historic Places or the California Register of Historical Resources.

4.14.3 SIGNIFICANCE CRITERIA

The CEQA Guidelines (Appendix G) (Governor’s Office, 1997) indicate that a project would normally have a significant impact on the environment if it would: disrupt or adversely affect a prehistoric or historic archaeological site or a property of historic or cultural significance in a community or ethnic or social group; or a paleontological site; except as part of a scientific study. This rather broad criterion of impact/effect has been interpreted by agencies to apply to significant or important sites. Cultural resource sites must be evaluated to determine if a given resource (prehistoric or historic) is important. Resources are found to be important if they are: (1) associated with an event or person of recognized significance in California or American history or has recognized scientific importance in prehistory; (2) can provide information that is of both demonstrable public interest and useful in addressing scientifically consequential and reasonable archaeological research questions; (3) has a special or particular quality such as oldest, best example, largest, or last surviving of its kind; (4) is at least 100 years old and possesses substantial stratigraphic integrity (although the Office of Historic Preservation, and many local agencies and municipalities, apply a 45- to 50-year-old criteria); (5) involves important research questions that historical research has shown can be answered only with archaeological methods.

4.14.4 IMPACTS AND MITIGATION MEASURES

None.

None.

None required.

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REFERENCES – Cultural Resources