Document elcerrito_gov_doc_4f39782fde

801 BATES AVENUE SUBDIVISION INITIAL STUDY APPENDICES Prepared for City of El Cerrito Planning Division 10890 San Pablo Avenue El Cerrito, CA 94530 Prepared by Design, Community & Environment 1625 Shattuck Avenue, Suite 300 Berkeley, CA 94709 October 19, 2010 ---PAGE BREAK--- ---PAGE BREAK--- A P P E N D I X A E X I S T I N G S T R U C T U R E S M A P ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- A P P E N D I X B T E N T A T I V E P A R C E L M A P W I T H T R E E R E M O V A L P L A N ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- A P P E N D I X C H I S T O R I C R E S O U R C E S U R V E Y R E P O R T ---PAGE BREAK--- ---PAGE BREAK--- imagining change in historic environments through design, research, and technology Page & Turnbull 801 BATES AVENUE EL CERRITO, CA HISTORIC RESOURCE TECHNICAL REPORT FINAL [10118] Prepared for Design, Community & Environment (DC&E) SEPTEMBER 8, 2010 DRAFT ---PAGE BREAK--- Historic Resource Technical Report 801 Bates Avenue Final El Cerrito, California September 8, 2010 Page & Turnbull, Inc. TABLE OF CONTENTS I. 1 1 II. SUMMARY OF 3 III. CURRENT HISTORIC STATUS 4 NATIONAL REGISTER OF HISTORIC 4 CALIFORNIA REGISTER OF HISTORICAL 4 CALIFORNIA HISTORICAL RESOURCE STATUS 4 EL CERRITO CITY 4 1976 PRELIMINARY HISTORIC RESOURCES REPORT, CONTRA COSTA 5 AND THE 1986 REVISED PRELIMINARY HISTORIC RESOURCES 5 IV. ARCHITECTURAL 6 6 8 11 V. HISTORIC CONTEXT 12 EL 12 801 BATES 14 VI. 24 CALIFORNIA REGISTER OF HISTORICAL 24 25 VIII. PROPOSED PROJECT ANALYSIS 27 A. PROPOSED PROJECT DESCRIPTION 27 B. CALIFORNIA ENVIRONMENT QUALITY ACT 27 C. STATUS OF EXISTING BUILDING AS A HISTORIC RESOURCE 28 D. DETERMINATION OF SIGNIFICANT ADVERSE CHANGE UNDER CEQA 29 IX. CONCLUSION 29 X. REFERENCES 30 PUBLISHED 30 PUBLIC RECORDS 30 NEWSPAPERS AND 30 INTERNET SOURCES 30 ---PAGE BREAK--- Historic Resource Technical Report 801 Bates Avenue Final El Cerrito, California September 8, 2010 Page & Turnbull, Inc. - 1 - I. INTRODUCTION This Historic Resources Technical Report has been prepared at the request of Design Community & Environment (DC&E) for the proposed demolition of the house and subdivision of the 46,300 square-foot property at 801 Bates Avenue (APN 505-282-027) (Figure The existing single-family house was constructed in 1932 for the Gill family, and the original architect is unknown. The three-story wood frame building was designed in the Spanish Eclectic style, and has undergone many significant alterations over time, including: a three-story addition with ground floor garages, reconstruction of an enclosed circular staircase, replacement windows and new window openings, the filling in of a pool on the south side of the house, and construction of a new pool and pool enclosure to the west. The building has also undergone numerous interior alterations. 801 Bates Avenue is still used as single-family house, but also contains an in-law unit that is a later addition. Figure 1: Location of the 801 Bates Avenue, El Cerrito. (Source: Microsoft maps, 2010). 801 Bates Avenue is not listed in any national, state, or local historic registers, nor is it located within the boundaries of any local historic districts. The building was inventoried in the 1976 Preliminary Historic Resources Report, Contra Costa County and the 1986 Revised Preliminary Historic Resources Inventory, in which it was called out as an “Architectural Specimen” (as opposed to a “Structure of Historical Significance”). It is also listed in the California Historic Resource Inventory System with a “7N” (“Needs to be reevaluated”) and a “7R” (“Identified in Reconnaissance Survey: Not evaluated”). The proposed project at 801 Bates Avenue involves the demolition of the existing building, subdivision of the property into four new properties, and the construction of a single-family house on each of the four properties. METHODOLOGY This report provides a physical description and historic context for 801 Bates Avenue, as well as an examination of the existing historical status of the property. The report includes an evaluation of the property’s eligibility for the California Register of Historical Resources (California Register) and an evaluation of the proposed project under the provisions of the California Environmental Quality Act (CEQA). Any proposed alterations to the building will be considered by the El Cerrito Planning Department as part of the CEQA review process. ---PAGE BREAK--- Historic Resource Technical Report 801 Bates Avenue Final El Cerrito, California September 8, 2010 Page & Turnbull, Inc. - 2 - Page & Turnbull prepared this report using research collected at various local repositories, including the El Cerrito Public Library, El Cerrito Historical Society, El Cerrito Planning Department, Online Archive of California, and other internet resources. ---PAGE BREAK--- Historic Resource Technical Report 801 Bates Avenue Final El Cerrito, California September 8, 2010 Page & Turnbull, Inc. - 3 - II. SUMMARY OF DETERMINATION 801 Bates Avenue does not appear to be individually eligible for listing in the California Register. Though constructed for a relatively prominent East Bay family as one of the earliest houses in the El Cerrito hills, the building has been altered significantly over the years and does not retain sufficient historic integrity to adequately convey any potential historic significance. The project sponsors propose demolishing 801 Bates Avenue and subdividing the property, while keeping the new properties within family ownership. Because the building at 801 Bates Avenue is not eligible for the California Register, it does not require compliance with the Secretary of the Interior’s Standards for the Treatment of Historic Properties. The project would not cause a significant adverse impact under CEQA, and no mitigation is required. ---PAGE BREAK--- Historic Resource Technical Report 801 Bates Avenue Final El Cerrito, California September 8, 2010 Page & Turnbull, Inc. - 4 - III. CURRENT HISTORIC STATUS The following section examines the national, state, and local historical ratings currently assigned to 801 Bates Avenue: NATIONAL REGISTER OF HISTORIC PLACES The National Register of Historic Places (National Register) is the nation’s most comprehensive inventory of historic resources. The National Register is administered by the National Park Service and includes buildings, structures, sites, objects, and districts that possess historic, architectural, engineering, archaeological, or cultural significance at the national, state, or local level. 801 Bates Avenue is not currently listed in the National Register, nor has it been identified or previously evaluated for eligibility for listing in the National Register. CALIFORNIA REGISTER OF HISTORICAL RESOURCES The California Register of Historical Resources (California Register) is an inventory of significant architectural, archaeological, and historic resources in the State of California. Resources can be listed in the California Register through a number of methods. State Historical Landmarks and National Register-listed properties are automatically listed in the California Register. Properties can also be nominated to the California Register by local governments, private organizations, or citizens. The evaluative criteria used by the California Register for determining eligibility are closely based on those developed by the National Park Service for the National Register of Historic Places. 801 Bates Avenue is not currently listed in the California Register, nor has it been previously evaluated for eligibility for listing in the California Register. CALIFORNIA HISTORICAL RESOURCE STATUS CODE Properties listed or under review by the State of California Office of Historic Preservation are assigned a California Historical Resource Status Code (Status Code) of to to establish their historical significance in relation to the National Register of Historic Places or California Register of Historical Resources. These assigned Status Codes are inventoried in the California Historic Resources Information System (CHRIS) database. Properties with a Status Code of or are either eligible for listing in the California Register or the National Register, or are already listed in one or both of the registers. Properties assigned Status Codes of or appear to be eligible for listing in either register, but normally require more research to support this rating. Properties assigned a Status Code of have typically been determined to be locally significant or to have contextual importance. Properties with a Status Code of are not eligible for listing in either register. Finally, a Status Code of means that the resource has not been evaluated for the National Register or the California Register, or needs reevaluation. 801 Bates Avenue is listed in the California Historic Resource Inventory System with a “7N” (“Needs to be reevaluated”) and a “7R” (“Identified in Reconnaissance Survey: Not evaluated”). EL CERRITO CITY LANDMARKS El Cerrito does not have a local landmarks program, nor does it have any local historic districts. ---PAGE BREAK--- Historic Resource Technical Report 801 Bates Avenue Final El Cerrito, California September 8, 2010 Page & Turnbull, Inc. - 5 - 1976 PRELIMINARY HISTORIC RESOURCES REPORT, CONTRA COSTA COUNTY AND THE 1986 REVISED PRELIMINARY HISTORIC RESOURCES INVENTORY The 1976 Preliminary Historic Resources Report, Contra Costa County and the 1986 Revised Preliminary Historic Resources Inventory were prepared by the Contra Costa County Community Development Department with the cooperation and assistance of various city historical societies in Contra Costa County. The inventory included properties in the Antioch, Clayton, Concord, East Contra Costa County, El Cerrito, Lafayette, Martinez, Moraga, North Coast, Orinda, Pacheco, Pinole, Pittsburg, Pleasant Hill, Richmond, San Pablo, San Ramon Valley, and Walnut Creek areas. The inventory included the following evaluation categories: “Structure of Historical Significance,” “Architectural Specimen,” “Site of Historical Significance,” “Site of Historic Event,” and “Site Relating to Important Person in History.” 801 Bates Avenue (Gill Estate) was inventoried in the 1976 Preliminary Historic Resources Report, Contra Costa County and the 1986 Revised Preliminary Historic Resources Inventory, in which it was called out as an “Architectural Specimen.” The description for the “Gill Estate” reads: “A unique styled mansion located on a promontory overlooking the Bay Area. The structural features include a tower, exterior chimney, large bays with windows, a tiled high gabled roof and a gabled entrance.” ---PAGE BREAK--- Historic Resource Technical Report 801 Bates Avenue Final El Cerrito, California September 8, 2010 Page & Turnbull, Inc. - 6 - IV. ARCHITECTURAL DESCRIPTION SITE 801 Bates Avenue is located on a 46,300 square-foot parcel on the southwest side of Bates Avenue, at the intersection of Roberta Drive in the El Cerrito hills (Figure The three-story, single-family house occupies the center of the parcel and faces northeast, toward Bates Avenue. Constructed in 1932, 801 Bates Avenue is a wood-frame residence designed in the Spanish Eclectic style. The building has a generally rectangular plan, is clad in textured stucco and rests on a concrete foundation. It is capped by a cross-gable roof covered in clay tiles. The property is separated from the street by a tall hedge, and the driveway is accessed via a gated entrance flanked by fieldstone pylons capped by urns at the north corner of the lot (Figure The first part of the driveway runs parallel to Bates Avenue. The south side of the property slopes toward Gelston Place. Figure 2. 801 Bates Avenue, view west from Roberta Drive. (Source: Page & Turnbull, August 2010). The large yard includes a circular stone and concrete bench at the northwest corner (Figure a stone fountain on the south side of the house (Figure and a stepped fieldstone wall at the west side, before a grade change down the hill to the west. Several narrow terraced levels of land are located to the southwest, and are accessed by wood stairs. A concrete pedestal is partially buried under the trees east of the house, with the words “Ceres Antique” inscribed in the base. It appears that the pedestal may have once supported a statue of the Roman goddess Ceres. The property features an unobstructed view west to San Francisco, the Golden Gate, Marin, and the North Bay (Figure Figure 3. Gate and driveway from Bates Avenue. Figure 4. Stone and concrete bench surrounded by (Source: Page & Turnbull, August 2010). brush. (Source: Page & Turnbull, August 2010). ---PAGE BREAK--- Historic Resource Technical Report 801 Bates Avenue Final El Cerrito, California September 8, 2010 Page & Turnbull, Inc. - 7 - Figure 5. Fountain southeast of the house. Figure 6. View west toward San Francisco. (Source: Page & Turnbull, August 2010). (Source: Page & Turnbull, August 2010). Closer to the house, the narrow strip of level yard at the rear (west side) contains an empty swimming pool and diving board, enclosed by a wood frame structure that includes walls on three sides and a shed roof (Figure The west side features wood walls and aluminum-sash sliding windows, which sit upon the stone site wall (Figure The north and south ends of the enclosure contain aluminum-sash windows and fully glazed sliding doors. The east side is open to the house, supported by wood posts, and separated from a small concrete patio by a three-foot concrete wall clad in small multi-colored ceramic tiles. Concrete steps at the north end lead from the pool enclosure to a concrete patio, which is enclosed by wood walls with inset sliding aluminum-sash windows, which sit atop the fieldstone site wall (Figure A wood deck with wood stairs is located to the south of the house (Figure 10). [Note: Historical pictures of the site, and some borings carried out for a geotechnical report, revealed that an old swimming pool was once located on the south side of the house. It has since been filled in and there is no more surface trace of the pool.] Figure 7. Swimming pool and enclosure. Figure 8. West wall of pool enclosure, (Source: Page & Turnbull, August 2010). atop fieldstone site wall. (Source: Page & Turnbull, August 2010). ---PAGE BREAK--- Historic Resource Technical Report 801 Bates Avenue Final El Cerrito, California September 8, 2010 Page & Turnbull, Inc. - 8 - Figure 9. Patio enclosed by wood walls and sliding Figure 10. Wood deck to the south. windows. (Source: Page & Turnbull, August 2010). (Source: Page & Turnbull, August 2010). EXTERIOR Primary (Northeast) Facade The primary façade faces northeast toward Bates Avenue (Figure 11). The façade is divided into two sections. The east section projects and features a side-facing gable with a concrete chimney with three chimney pots. Two front-facing gables feature wavy wood trim beneath clay tiles. The eastern-most bay contains two arched aluminum windows containing sliding operable sash at the first story, three fixed aluminum-sash windows at the second story, and an arched fixed wood-sash window under the gable. The center bay features broad brick steps with concrete wing walls and metal railings, which lead to a recessed entry at the second story, under a wide Tudor arch (Figure 12). The entry contains a wood plank door with large metal hinges, flanked by fixed wood sash windows, and a multi-light wood door with sidelights on the north wall (Figure 13). An arched fixed wood-sash window is located under the gable, above the entry. The third bay contains a cylindrical solarium at the second story, supported by arcaded concrete posts below. The solarium features narrow vertical fixed aluminum-sash windows, and is capped by a crenellated parapet. A rectangular section of gabled corrugated metal is visible from the interior ceiling. Three fixed wood-sash windows face north toward the recessed north section. Figure 11. Primary façade, facing northeast. (Source: Page & Turnbull, August 2010). ---PAGE BREAK--- Historic Resource Technical Report 801 Bates Avenue Final El Cerrito, California September 8, 2010 Page & Turnbull, Inc. - 9 - Figure 12. Primary entry stairs. Figure 13. Primary entrance porch. (Source: Page & Turnbull, August 2010). (Source: Page & Turnbull, August 2010). The north section is a three-story addition that features a three-car garage with a two-car roll-up garage door and a one-car roll-up garage door on the first story (Figure 14). An in-law unit entry with a flush wood door is located south of the garage doors. A pent roof clad in clay tiles caps the first story level. The second story contains two horizontal sliding aluminum-sash windows and two octagonal windows inset with reflective glass. The third story features three sliding aluminum-sash windows. Figure 14. North section of primary façade, looking south. (Source: Page & Turnbull, August 2010). Northwest and Southeast Façades The northwest façade contains one sliding aluminum-sash window on the first story, two sliding aluminum-sash windows at the second and third stories, and an attic vent at the gable apex (Figure 15). The southeast façade features a cylindrical stair tower at the west corner, containing round-headed fixed aluminum-sash windows at the first and second stories and capped by a pointed eight-sided clay tile roof (Figures 16 and 17). A stuccoed exterior chimney separates the corner tower from the rest of the façade. To the east, the first story features multi-light wood French doors and sidelights under a projecting eave, which lead to the wood deck (Figure 18). The second story contains three rectangular sliding aluminum-sash windows, as well as two round-headed fixed aluminum-sash ---PAGE BREAK--- Historic Resource Technical Report 801 Bates Avenue Final El Cerrito, California September 8, 2010 Page & Turnbull, Inc. - 10 - windows that are set in a projecting section with a clay tile hip roof. The third story features a Palladian window arrangement of two vertical rectangular windows flanking a round-headed window. All three contain fixed aluminum sash. A circular fixed window is set in the gable apex. Figure 16. Northwest façade. Figure 17. Southeast façade and southern yard. (Source: Page & Turnbull, August 2010). (Source: Page & Turnbull, August 2010). Figure 18. Rear stair tower. Figure 19. Southeast façade. (Source: Page & Turnbull, August 2010). (Source: Page & Turnbull, August 2010). Southwest Facade The southwest façade is arranged in three sections (Figure 20). The southern-most section projects and features two sliding aluminum-sash windows at the first story; a round-headed window flanked by two rectangular windows, all fixed aluminum-sash, at the second story; and a circular fixed window in the apex of the front-facing gable. Two multi-light wood doors face north from the first and second stories; it appears that a balcony once projected from the second story, as the door at that level does not lead anywhere (Figure 21). The center section of the southwest façade features a boarded-up window and a sliding aluminum-sash window at the first story, two sliding aluminum- sash windows at the second story, and a single window of the same type at the third story, under a front-facing gable. The northern-most section is the rear of the garage addition. The entire three- story façade has been covered with a blue tarp; parts of the façade have been removed underneath, ---PAGE BREAK--- Historic Resource Technical Report 801 Bates Avenue Final El Cerrito, California September 8, 2010 Page & Turnbull, Inc. - 11 - due to dry rot and mold. The first story level of this section projects and a multi-light wood door faces south toward the small rear patio. This section terminates in a side-facing gable. Figure 19. Rear (southwest) façade, looking east. Figure 20. Doors at southwest façade. (Source: Page & Turnbull, August 2010). (Source: Page & Turnbull, August 2010). INTERIOR The interior of 801 Bates Avenue was not accessible to Page & Turnbull during the site visit, but it appears that the interior has been completely modernized and does not contain original features and finishes. Through the windows, it is apparent that rooms include such features as relatively new hardwood floors, recessed ceiling lights, plaster walls without moldings, and a relatively new turned wood spiral staircase in the southwest stair tower. ---PAGE BREAK--- Historic Resource Technical Report 801 Bates Avenue Final El Cerrito, California September 8, 2010 Page & Turnbull, Inc. - 12 - V. HISTORIC CONTEXT EL CERRITO The original inhabitants of the El Cerrito area were the Ohlone Indians. The first European contact with Contra Costa County came in 1772 through a Spanish exploration led by Pedro Fagas and Fr. Juan Crespi. Their troop of twelve soldiers camped on the bank opposite the Golden Gate, and named the hill “Serrito [sic] de San Antonio,” after the little hill that became the namesake for the city of El Cerrito.1 Prior to the Mexican revolution, in the early 1820s, Contra Costa County was used as grazing land for sheep and cattle belonging to Mission Dolores in San Francisco. Following the revolution in 1823, Francisco Castro, a former soldier at the Presidio of San Francisco and alcalde (mayor) of San Jose, received a provisional grant for approximately four square leagues (19,394.40 acres) from Governor Arguello. The grant, called Rancho San Pablo, was finalized in 1834. It included all the land between San Pablo Creek on the north, Cerrito Creek on the south, the San Francisco Bay on the west, and the top of the ridge to the east (present-day San Pablo, Richmond, and El Cerrito). While Francisco Castro established his family in an old mission dwelling near present-day San Pablo, one of his sons, Victor Ramon Castro, established a hacienda at the southern end of his father’s rancho in 1839. This hacienda, known today as the Castro Adobe, was located at the site of the present El Cerrito Shopping Center until a fire destroyed it in 1956. Victor Castro raised cattle, fruit, grains, and vegetables on his rancho lands.2 He leased sections of his land to others, and eventually lost nearly all of it through poor management and land swindling by Americans. The area continued to be sparsely settled through most of the nineteenth century. In 1850, the California legislature divided the state into twenty-seven counties, including Contra Costa County. El Cerrito, which was called “County Line” at the time, was part of San Pablo township, whose boundaries generally followed those of the San Pablo Rancho.3 William F. Rust, a journeyman blacksmith from Hanover, Germany, arrived in San Pablo in 1883 and soon after built a blacksmith shop on the main road (now San Pablo Avenue) just north of the Alameda-Contra Costa County line (Figure 21). He is credited as one of the founders of El Cerrito, though a few other Americans had settled in the area before him, including a farmer named John Davis. As Rancho San Pablo was excellent farming land, Rust began making farm implements for which there was great demand. In 1909, a post office was established in Rust’s store, and County Line became known as “Rust” thereafter.4 1 El Cerrito Historical Society, Images of America: El Cerrito (Charleston, S.C.: Arcadia Publishing, 2005) 7. 2 Ibid. 3 Edward Staniford, El Cerrito: Historical Evolution (El Cerrito, CA: El Cerrito-Kensington Bicentennial Committee, 1976) 18. 4 Ibid. ---PAGE BREAK--- Historic Resource Technical Report 801 Bates Avenue Final El Cerrito, California September 8, 2010 Page & Turnbull, Inc. - 13 - Figure 21. William Rust’s blacksmith shop (far left) and other buildings in County Line, ca. 1895. (Source: George Emanuels, California’s Contra Costa County: An Illustrated History: 125). Little changed until 1890, when two Berkeley realtors, George Schmidt and Anson Blake, began dividing large farms into smaller farms and residential lots for resale (Figure 22). In 1898, the men opened Schmidt Village, offering five acre tracts and home sites. This development attracted new residents, who set up commercial businesses on San Pablo Avenue.5 The residents traveled to Berkeley and Richmond on the East Shore and Suburban Railway electric line, which was established in 1904.6 Around the same time, quarrying became the primary industry near Rust, an endeavor operated by the Bates and Borland Quarry and Tallentyne Hutchinson Quarry. Nevertheless, much of the area still contained dairies and chicken farms. Figure 22. El Cerrito residences and small farms, ca. 1900. (Source: El Cerrito Historical Society, Images of America: El Cerrito: 23). 5 George Emanuels, California’s Contra Costa County: An Illustrated History (Fresno, CA: Panorama Books, 1986) 126. 6 Edward Staniford, El Cerrito: Historical Evolution: 32. ---PAGE BREAK--- Historic Resource Technical Report 801 Bates Avenue Final El Cerrito, California September 8, 2010 Page & Turnbull, Inc. - 14 - On August 23, 1917, the unincorporated areas of Rust and adjacent Stege Junction voted on incorporation, in order to raise tax money for services such as fire and police protection and street paving.7 The resulting city was named El Cerrito, and had an estimated population of 1,400 that year. During Prohibition in the 1920s, the saloons and other businesses on San Pablo Avenue were gradually replaced by auto-related businesses, including garages, service stations, auto courts, and motels. Houses were developed on both sides of San Pablo Avenue for several blocks and on the hillside within proximity of the railroad depots.8 Residents were primarily in the middle-lower income brackets. The town reached a population of 3,852 in 1930. Legalized gambling made El Cerrito a recreational destination in the 1930s. At that time, the town contained casinos and a greyhound dog racing track for the El Cerrito Kennel Club.9 El Cerrito experienced a rise in property development beginning in 1938, as the nation emerged from the Great Depression. Piecemeal development of the hillside tracts below Arlington Boulevard sped up, and the town’s population reached 7,000 in 1940. However, during World War II, the population jumped to nearly 17,000 as people flooded into the Bay Area to work in the defense industry. Approximately half of El Cerrito’s population at that time lived in temporary war housing or government trailer parks, and many worked in the Richmond shipyards. During the post-war building boom, the population jumped to 25,000. Residents and newcomers built single-family homes on attractive hillside sites overlooking the San Francisco Bay and the Golden Gate, while developers built apartment buildings and duplexes in the flat area. In 1946, the slogan “The City of Homes” was adopted. About the same time, a new city council was elected. One of their first major acts was to embark on a vigorous enforcement campaign against all gambling activity. The building boom continued through the 1950s and into the 1960s, when residential tracts filled out the hillside area and construction slowed down. By 1976, the city comprised 2,300 acres or 3.7 miles, of which 71 percent was developed, 23 percent was right of way for public utilities, and the remaining 7 percent was vacant. BART was constructed through El Cerrito in the 1960s, as well, which helped strengthen the city’s role as a bedroom community to Berkeley, Oakland, and San Francisco.10 In 2000, the population was 23,171 people. 801 BATES AVENUE The site of 801 Bates Avenue was owned and developed by Edward Clifford Gill, the second son of Edward G. Gill, a horticulturalist and nursery businessman known throughout the Bay Area for the exotic plants and antique roses that he raised. 11 Edward G. and Mary Gill were born in Ireland in about 1840 and 1842, respectively, but came to California before their first child was born in 1869. The Gills had four children: John (born in January 1869), Edward C. (born in February 1871), Sarah Isabella (born in November 1877) and Mary Elizabeth (born in May 1880).12 They lived in Oakland in 1880.13 7 El Cerrito Historical Society, “El Cerrito History,” Website accessed on 5 August 2010 from: http://www.el- cerrito.org/community/history.html 8 Edward Staniford, El Cerrito: Historical Evolution: 32. 9 Ibid: 127. 10 Ibid: 87. 11 Mervin Belfils, “The Community’s Past- The El Cerrito Historical Society. Website accessed on 5 August 2010 from: http://elcerritowire.com/history/pages/communityspast3.htm. 12 Note: Another Gill family resided in El Cerrito at the turn of the twentieth century, but do not appear to be related to the Edward E. Gill family. Etta Gill McHenry and Charles C. Gill owned a tract of land at San Pablo Avenue and Cutting Boulevard. Gill Avenue was named after them and a California & Nevada railroad station nearby was called Gills Station. (Source: Tom Panas of the El Cerrito Historical Society and Gill’s Addition to Pullman, Contra Costa County (1911) map). 13 1880 U.S. Census. Website accessed on 9 August 2010 from: Ancestry.com. ---PAGE BREAK--- Historic Resource Technical Report 801 Bates Avenue Final El Cerrito, California September 8, 2010 Page & Turnbull, Inc. - 15 - In 1889, Gill bought a 104-acre nursery at Marin and San Pablo Avenues in Albany, which was originally partitioned three years earlier as the White and Driver Tract. His family moved to a large Victorian home on the property (address on San Pablo Avenue), where they were listed in the 1900 U.S. Census (Figure 23). Edward G. Gill died in 1909 at his home. His eldest son, John, constructed a Craftsman style house on the nursery property around 1910 as his residence, while continuing to farm the land.14 The Gill children sold the nursery to the University of California in January 1928, and John Gill died later that year. Over the course of the next 65 years, the land was subdivided and some plots sold. Currently, there are 14 remaining acres of the Gill Tract, 9.7 of which are arable land.15 Figure 23. The Edward G. Gill home in Albany, ca. 1900. Edward Gill appears to the left of the horses, John Gill at the center, and Isabelle Gill on the steps. (Source: Karen Sorensen and the Albany Historical Society, Images of America: Albany (Charleston, SC: Arcadia Publishing) 15). Second son Edward Clifford Gill was also listed as a horticulturist in the U.S. Census records between 1910 and 1930, though he lived in the Hotel Royal, a residential hotel on San Pablo Avenue, in 1920 and 1930. He was apparently also a professor and doctor.16 According to local historian Mervin Belfils, Edward C. Gill purchased 801 Bates Avenue in the Rancho San Pablo Tract of the El Cerrito hills around 1927.17 When the property was purchased, it was a barren, rocky lot without any trees. Gill started landscaping the original six acres, planting fruit trees and imported shrubs. The rear of the property contained a pond stocked with large trout. According to the newspaper article, Its trees, shrubs, and flowers were of the best and rarest varieties, as they were brought from the famous Gill Nurseries, which Dr. Gill’s parents had founded in 14 LSA, Report, Experiment Station Research and History- Gill Tract, University of California, Albany, CA (University of California, Berkeley, October 2009) 7. Website accessed on 11 August 2010 from: http://www.cp.berkeley.edu/CP/PEP/History/Reports_and_Studies/Gill_Tract_Experiment_Station_Histor y.pdf 15 “Frequently Asked Questions,” The Gill Tract. Website accessed on 5 August 2010 from: http://gilltract.org/Information.html 16 Barclay, “El Cerrito ‘Sanctuary’ is Rich in History,” The San Francisco Chronicle (17 May 1953): clipping- page unknown. 17 Mervin Belfils, “The Community’s Past- The El Cerrito Historical Society. Website accessed on 5 August 2010 from: http://elcerritowire.com/history/pages/communityspast3.htm. ---PAGE BREAK--- Historic Resource Technical Report 801 Bates Avenue Final El Cerrito, California September 8, 2010 Page & Turnbull, Inc. - 16 - West Berkeley in 1889. Full-size mimosas, or acacia trees as they are more commonly called, were planted around the boundaries of the property and it was given the name of “Las Mimosas” Since Dr. Gill’s hobby was reassembling statuary from Woodward’s Gardens, and collecting other pieces that took his fancy, the garden used to be a setting for lovely marble statues and a marble fountain moved in sections from Woodward’s Gardens. Some of the pieces came from the Leland Stanford collection and had never been uncrated before being bought by Dr. Gill.18 (Figure 24). Figure 24. A marble statue, one of Dr. Gill’s acquisitions, in the cylindrical solarium at Las Mimosas, n.d. (Source: Barclay, “El Cerrito ‘Sanctuary’ is Rich in History,” The San Francisco Chronicle, 17 May 1953). Soon after Edward C. Gill purchased and began to landscape the property at 801 Bates Avenue, the Gill family sold the nursery to the University of California. Dr. Gill did not build the house on his estate until 1932. He planned his home to be located at the top of a knoll overlooking San Francisco and the Golden Gate. The original architect is unknown and no Sanborn Fire Insurance maps exist for the area to map development over time. The house was built on solid rock that had been leveled off.19 Though the house was imposing and designed in a turreted Spanish Eclectic style, it contained only two bedrooms and was regarded as a studious retreat rather than a place to entertain guests (Figure 25). As an antique collector, Dr. Gill furnished his home with rare objects, such as an Ardebil rug, made circa 1800 and valued at $25,000; a solid marble table in the entry hall; and tapestried chairs from Ralston Mansion, across the Bay in Belmont.20 The chandeliers were reportedly purchased from the Winchester family of Winchester Rifle and Winchester Mystery House fame. Dr. Gill and his wife, Ann, lived in the house for seventeen years.21 According to the California Death Index, Dr. Gill died in October 1949 in Alameda.22 His widow subsequently put his art collection on sale, including the statues of Swiss halberdiers, which guarded the two entrances to Las 18 Ibid. 19 Ibid. 20 Barclay, “El Cerrito ‘Sanctuary’ is Rich in History,” The San Francisco Chronicle (17 May 1953): clipping- page unknown. 21 Ibid. 22 California Death Index, 1940-1997. Website accessed on 16 August 2010 from: www.ancestry.com. ---PAGE BREAK--- Historic Resource Technical Report 801 Bates Avenue Final El Cerrito, California September 8, 2010 Page & Turnbull, Inc. - 17 - Mimosas.23 After selling the house, Mrs. Gill spent about eight months of the year in New York and returned to the Claremont Hotel in Berkeley for summer visits. Figure 25. South and east facades and statues in the yard, n.d. (pre-1949). Compared to the photographs in the above Architectural Description section, note the shorter rear tower (at left), the different fenestration pattern on the south façade, and termination of the building just beyond the circular solarium at the front of the house. (Source: Barclay, “El Cerrito ‘Sanctuary’ is Rich in History,” The San Francisco Chronicle, 17 May 1953) Figure 26. Aerial View of the Gill Estate with house in near top center, as it existed when Victor Stallone purchased the property in 1949. Compare to Figure 1 for changes to property and surrounding neighborhood over time. (Source: Jim Joyce, 2010). 23 Barclay, “El Cerrito ‘Sanctuary’ is Rich in History,” The San Francisco Chronicle (17 May 1953) page unknown. ---PAGE BREAK--- Historic Resource Technical Report 801 Bates Avenue Final El Cerrito, California September 8, 2010 Page & Turnbull, Inc. - 18 - Following the death of Dr. Edward C. Gill, Dr. Victor Stallone purchased the property in 1949 and lived there with his wife and children (Figure 26). Dr. Stallone was a 1944 graduate of the University of California, San Francisco, School of Medicine, and a member of the Alameda-Contra Costa Medical Association. By 1975, the house had eleven rooms and five baths. Stallone added the rear patio, pool, and pool cover, among other alterations. Dr. Stallone died in Albany on 22 January 1990 at age 70. During Dr. Stallone’s period of ownership, portions of the original six acre property were subdivided into smaller parcels and houses were built on them. Acres of trees and shrubs were replaced with new streets and homes. In 1953, the property reportedly contained four acres, and by 1975, two acres of the property remained.24 Today, the property comprises a little over one acre. A good part of the rose garden, Dr. Gill’s great pride, remained in 1953, but the three hundred camellia bushes that had covered a hillside were removed. Most of the lower triangle of the estate was so overgrown by this time with tree-size shrubs and thickly entwined vines that it was almost impossible to follow the paths.25 Inquiring as to whether the original owner, Mrs. Edward C. Gill, ever visited her old house, the San Francisco Chronicle stated that “[she] has no desire to see Las Mimosas again. She remembers her years there with happiness, but [says] that, as with so many of California’s old estates, progress has chopped up and destroyed instead of improving it.”26 Mr. Alan Lau purchased the property from Dr. Stallone some time between 1983 and 1987. Lau has made many additions to the residence, including a new wing to the north, an in-law unit, a new rear stair tower, a new west exterior wall, and the installation of replacement windows. ALTERATIONS 1932 The house is constructed for Dr. Edward C. Gill and his wife, Ann. No original building permit is on file at either the El Cerrito Planning Department or the Contra Costa County Assessor’s Office. The original architect is unknown. Ca. 1949-1953 At least two acres of the landscaped area of the property were sold. Some of this was redeveloped into the houses of Gelston Place. The original exotic landscaping was not kept up. For example, the camellia bushes were removed, and other plants became overgrown. 1959 In March, Dr. Victor Stallone built a patio addition and conducted electrical work without a permit. He also installed a fence around the patio, a patio roof, and a brick fireplace for $520, after applying for a permit in May. The patio area enclosed by the fence was approximately 24’ x 36’ and a roof was to cover approximately 18’ x 20.’ 1960 In August, Dr. Victor Stallone submitted an application for a building permit to remodel the house. The Architect was Bay Group Assoc. and the contractor was Dyer & Truitt. The project cost an estimated $14,000. 24 Ibid; Mervin Belfils, “The Community’s Past- The El Cerrito Historical Society. 25 Barclay, “El Cerrito ‘Sanctuary’ is Rich in History,” The San Francisco Chronicle (17 May 1953) page unknown. 26 Ibid. ---PAGE BREAK--- Historic Resource Technical Report 801 Bates Avenue Final El Cerrito, California September 8, 2010 Page & Turnbull, Inc. - 19 - 1964 In November, Dr. Victor Stallone built a 262’ long and 32” high retaining wall of railroad ties on the westerly boundary of the property, which cost an estimated $1,050. 1965 The City of El Cerrito removed half of the fill behind Dr. Stallone’s redwood tie retaining wall along the westerly property line, which was in a hazardous condition. The city regarded the hill behind the wall to lessen the load on the retaining wall. 1966 In June, Dr. Victor Stallone hired Alves Pools of Lafayette to install a 10’ x 12’ x 40’ swimming pool, which cost $6,000. In July, Dr. Stallone applied for a permit to remodel the kitchen for an estimated $4,000. A pool cover was constructed in September, which cost $3,092 and was designed by Dr. Frazee. 1972 Hershman Plumbing and Heating installed a water heater for Dr. Victor Stallone in November. 1983 In March, Dr. Victor Stallone hired Flagler Roofing to reroof the house for $1,550. 1987 Mr. Lau hired BW Construction to construct a three-story addition with a garage on the ground floor, a formal dining room on the second floor, and a master bedroom suite on the third floor (Figures 27 to 30). ---PAGE BREAK--- Historic Resource Technical Report 801 Bates Avenue Final El Cerrito, California September 8, 2010 Page & Turnbull, Inc. - 20 - Figure 27. Plot plan showing northwest addition in black, 1987. Figure 28. Primary façade showing northwest addition to the right, 1987. Compare to photographs in the previous section to see changes in fenestration in both the left bay and the addition between 1987 and 2010. ---PAGE BREAK--- Historic Resource Technical Report 801 Bates Avenue Final El Cerrito, California September 8, 2010 Page & Turnbull, Inc. - 21 - Figure 29. The rear façade, 1987. Note the changes in fenestration in the center and right bays between 1987 and 2010. Figure 30. Southeast and northwest facades, 1987. Compare to photographs in the Architectural Description section and Figure 25, and note the changes made to the fenestration both before 1987 and between 1987 and 2010. ---PAGE BREAK--- Historic Resource Technical Report 801 Bates Avenue Final El Cerrito, California September 8, 2010 Page & Turnbull, Inc. - 22 - 1989 Mr. Alan Lau built an accessory living unit in the house. 1993 Mr. Lau applied for a permit to repair water damage and dry rot by removing all stucco from the west (rear) side of the building, replacing windows as necessary, replacing damaged studs and sheeting, tearing off the roof and wall for the swimming pool, reframing, and replacing the stucco. The project’s contractor was SM Construction Co. and estimated at $18,000. The application was not finalized, and expired in July 1994. In December, Mr. Lau applied for a permit to demolish and rebuild the rear stair tower as per drawings. The contractor was SM Construction Co. and the project was estimated at $8,000 (Figure 31). 1995 In January, Mr. Alan Lau applied for a permit to remove all existing roof tiles and install fire safe concrete tiles for an estimated $25,000. Figure 31. Drawings to demolish and rebuild rear stair tower, 1993. 2000 In June, Mr. Meilin Lau was requested to remove broken tree limbs from the fence at the edge of the property. 2007 Water damage repairs were made, especially at the west façade. ---PAGE BREAK--- Historic Resource Technical Report 801 Bates Avenue Final El Cerrito, California September 8, 2010 Page & Turnbull, Inc. - 23 - 1987-2010 During this time, it appears that much of the fenestration was altered with the insertion of new window configurations on all facades. Compare the above drawings from 1987 with the historic photograph (Figure 25) and current photographs in the Architectural Description section. Along with changes in fenestration patterns, nearly all of the original windows have been replaced with aluminum sash, and the building appears to have been re-stuccoed at an unknown date, as well. ---PAGE BREAK--- Historic Resource Technical Report 801 Bates Avenue Final El Cerrito, California September 8, 2010 Page & Turnbull, Inc. - 24 - VI. EVALUATION CALIFORNIA REGISTER OF HISTORICAL RESOURCES The California Register of Historical Resources (California Register) is an inventory of significant architectural, archaeological, and historical resources in the State of California. Resources can be listed in the California Register through a number of methods. State Historical Landmarks and National Register-listed properties are automatically listed in the California Register. Properties can also be nominated to the California Register by local governments, private organizations, or citizens. The evaluative criteria used by the California Register for determining eligibility are closely based on those developed by the National Park Service for the National Register of Historic Places. In order for a property to be eligible for listing in the California Register, it must be found significant under one or more of the following criteria. ƒ Criterion 1 (Events): Resources that are associated with events that have made a significant contribution to the broad patterns of local or regional history, or the cultural heritage of California or the United States. ƒ Criterion 2 (Persons): Resources that are associated with the lives of persons important to local, California, or national history. ƒ Criterion 3 (Architecture): Resources that embody the distinctive characteristics of a type, period, region, or method of construction, or represent the work of a master, or possess high artistic values. ƒ Criterion 4 (Information Potential): Resources or sites that have yielded or have the potential to yield information important to the prehistory or history of the local area, California, or the nation. Resources eligible for the National Register are automatically listed in the California Register of Historical Resources.27 801 Bates Avenue does not appear to be individually eligible for listing in the California Register. Below is a discussion of how all four California Register Criteria apply in the case of 801 Bates Avenue. Criterion 1 (Event) 801 Bates Avenue does not appear to be associated with events that have made a significant contribution to patterns of our history such that it would be eligible under California Register Criterion 1 (Event). It appears to have been a relatively early residential property developed in the El Cerrito hills, though the town developed on and around San Pablo Avenue twenty to thirty years earlier. The house is not part of any significant neighborhood development, though, since the surrounding houses were developed several decades later and encroached over the original property lines. Thus, the building is not individually significant within this context to warrant listing in the California Register as an individual resource. 27 California Office of Historic Preservation, Technical Assistant Series No. 7, How to Nominate a Resource to the California Register of Historic Resources (Sacramento, CA: California Office of State Publishing, 4 September 2001) 11. ---PAGE BREAK--- Historic Resource Technical Report 801 Bates Avenue Final El Cerrito, California September 8, 2010 Page & Turnbull, Inc. - 25 - Criterion 2 (Person) 801 Bates Avenue appears significant under California Register Criterion 2 (Person). The property was owned and developed by Dr. Edward C. Gill, son of founding nurseryman Edward G. Gill of the Gill Tract in Albany, California. Dr. Gill was a horticulturalist, professor, and doctor who purchased, elaborately landscaped, and built a house at 801 Bates Avenue between 1927 and 1932. The house was a studious retreat for Dr. Gill, who lived there with his wife for seventeen years. He had the house designed for his specific needs, and landscaped the property with exotic plants and trees, a rose garden, fountain, and statues. Because the Gill Tract nursery was established by his father, later operated by his brother, and sold to the University of California about the time that Dr. Gill purchased 801 Bates Avenue, it appears that 801 Bates Avenue best represents the productive period of Dr. Gill’s life and his specific interests. Dr. Gill appears to have been a locally significant figure during the first half of the twentieth century. Thus, 801 Bates Avenue appears individually significant within this context under California Register Criterion 2. Criterion 3 (Architecture & Design) 801 Bates Avenue does not appear eligible for listing in the California Register under Criterion 3 (Architecture & Design). The house has been added onto and altered numerous times, to the extent that only half the building resembles its original form and style. Furthermore, the property has been greatly reduced in size, and the original distinctive landscaping patterns appear to have been truncated. Thus, 801 Bates Avenue does not embody the characteristics of a type, period, and method of construction. It also does not appear to represent the work of a master, as no information has been found that includes a discussion of the original architect, nor does the building feature high artistic value. Consequently, 801 Bates Avenue is not individually eligible for listing in the California Register under Criterion 3. Criterion 4 (Information Potential) The analysis of 801 Bates Avenue for eligibility under Criterion 4 (Information Potential) is beyond the scope of this report. This Criterion is typically reserved for archeological resources, and therefore it is not evaluated as part of this report. INTEGRITY In order to qualify for listing in the California Register, a property must possess significance under one of the aforementioned criteria and have historic integrity. The process of determining integrity is similar for both the California Register and the National Register. The same seven variables or aspects that define integrity—location, design, setting, materials, workmanship, feeling and association—are used to evaluate a resource’s eligibility for listing in the California Register and the National Register. According to the National Register Bulletin: How to Apply the National Register Criteria for Evaluation, these seven characteristics are defined as follows: Location is the place where the historic property was constructed. Design is the combination of elements that create the form, plans, space, structure and style of the property. Setting addresses the physical environment of the historic property inclusive of the landscape and spatial relationships of the building/s. ---PAGE BREAK--- Historic Resource Technical Report 801 Bates Avenue Final El Cerrito, California September 8, 2010 Page & Turnbull, Inc. - 26 - Materials refer to the physical elements that were combined or deposited during a particular period of time and in a particular pattern of configuration to form the historic property. Workmanship is the physical evidence of the crafts of a particular culture or people during any given period in history. Feeling is the property’s expression of the aesthetic or historic sense of a particular period of time. Association is the direct link between an important historic event or person and a historic property. 801 Bates Avenue has undergone many alterations over time that diminish its historic integrity. The building possesses integrity of location because it has not been moved from its original site. The house lacks integrity of design, materials, and workmanship because it has been significantly altered since its original construction. An addition at the north end greatly enlarged the size of the house, the window fenestration and materials were altered, the rear stair tower was replaced, and the house was re-clad and re-roofed, among other changes. Thus, the overall plan, massing and materials are not original to the 1932 design. 801 Bates Avenue does not retain integrity of setting because the original six acre property has been reduced to a little over one acre, the original pool filled, and a new covered pool and surrounding structure installed; Dr. Gill’s landscaping pattern was truncated by development of portions of the land, and the plants that remained were not maintained.. The stone retaining walls, circular viewing bench, fountain, and pedestal for a statue remain, but the property is now covered with sparsely landscaped areas or overgrown weeds. Without groundwater for irrigation, the original plantings did not last. Due to numerous alterations to the house and property, 801 Bates Avenue does not retain the integrity of feeling of a property developed ca. 1927-1932. The house lacks integrity of association because its connection to an important person, Dr. Edward C. Gill, has been severed by the many alterations that have enlarged the house, removed his exotic landscaping, and removed the majority of his garden follies. Overall, 801 Bates Avenue does not possess the historic integrity needed to be considered an individual historic resource. Because both historic significance and integrity are required for a property to be eligible for listing in the California Register, 801 Bates Avenue does not qualify for listing. ---PAGE BREAK--- Historic Resource Technical Report 801 Bates Avenue Final El Cerrito, California September 8, 2010 Page & Turnbull, Inc. - 27 - VIII. PROPOSED PROJECT ANALYSIS This section analyzes the project-specific impacts of the proposed project at 801 Bates Avenue on the environment, as required by the California Environmental Quality Act (CEQA). A. PROPOSED PROJECT DESCRIPTION The proposed project is to demolish the present house and subdivide the lot into four lots of roughly equal width (all bigger than the required 5,000 square feet for El Cerrito R1 Single Family Residential Zones), with new property lines running north-south. The Lau family, who owns the current lot, intends to build a single-family home on each subdivided lot for each of the Lau siblings. An easement will be provided, which will allow for the widening of Bates Avenue adjacent to the property. B. CALIFORNIA ENVIRONMENT QUALITY ACT (CEQA) The California Environment Quality Act (CEQA) is state legislation (Pub. Res. Code §21000 et seq.), which provides for the development and maintenance of a high quality environment for the present- day and future through the identification of significant environmental effects.28 For public agencies, the main goals of CEQA are to: 1. Identify the significant environmental effects of projects; and either 2. Avoid those significant environmental effects, where feasible; or 3. Mitigate those significant environmental effects, where feasible. CEQA applies to “projects” proposed to be undertaken or requiring approval from state or local government agencies. “Projects” are defined as “…activities which have the potential to have a physical impact on the environment and may include the enactment of zoning ordinances, the issuance of conditional use permits and the approval of tentative subdivision maps.”29 Historic and cultural resources are considered to be part of the environment. In general, the lead agency must complete the environmental review process as required by CEQA. The basic steps are: 1. Determine if the activity is a “project;” 2. Determine if the project is exempt from CEQA; 3. Perform an Initial Study to identify the environmental impacts of the Project and determine whether the identified impacts are “significant.” Based on the finding of significant impacts, the lead agency may prepare one of the following documents: a) Negative Declaration for findings of no “significant” impacts; b) Mitigated Negative Declaration for findings of “significant” impacts that may revise the Project to avoid or mitigate those “significant” impacts; c) Environmental Impact Report (EIR) for findings of “significant” impacts. 28 State of California, California Environmental Quality Act, http://ceres.ca.gov/topic/env_law/ceqa/summary.html, accessed 31 August 2007. 29 Ibid. ---PAGE BREAK--- Historic Resource Technical Report 801 Bates Avenue Final El Cerrito, California September 8, 2010 Page & Turnbull, Inc. - 28 - For the proposed project at 801 Bates Avenue, the City of El Cerrito will act as lead agency. This report will be utilized as a technical report in support of one of the aforementioned environmental review documents. C. STATUS OF EXISTING BUILDING AS A HISTORIC RESOURCE In completing an analysis of a project under CEQA, it must first be determined if the project site possesses any historic resource. Based on our analysis, 801 Bates Avenue fails to qualify as a historic resource under CEQA. A site may qualify as a historic resource if it falls within at least one of four categories listed in CEQA Guidelines Section 15064.5(a). The four categories are: 1. A resource listed in, or determined to be eligible by the State Historical Resources Commission, for listing in the California Register of Historical Resources (Pub. Res. Code SS5024.1, Title 14 CCR, Section 4850 et seq.). 2. A resource included in a local register of historical resources, as defined in Section 5020.1(k) of the Public Resources Code or identified as significant in an historical resource survey meeting the requirements of section 5024.1 of the Public Resources Code, shall be presumed to be historically or culturally significant. Public agencies must treat any such resource as significant unless the preponderance of evidence demonstrates that it is not historically or culturally significant. 3. Any object, building, structure, site, area, place, record, or manuscript which a lead agency determines to be historically significant or significant in the architectural, engineering, scientific, economic, agricultural, educational, social, political, military, or cultural annals of California may be considered to be an historical resource, provided the lead agency’s determination is supported by substantial evidence in light of the whole record. Generally, a resource shall be considered by the lead agency to be “historically significant” if the resource meets the criteria for listing on the California Register of Historical Resources (Pub. Res. Code SS5024.1, Title 14 CCR, Section 4852). 4. The fact that a resource is not listed in, or determined to be eligible for listing in the California Register of Historical Resources, not included in a local register of historical resources (pursuant to section 5020.1(k) of the Pub. Resources Code), or identified in an historical resources survey (meeting the criteria in section 5024.1(g) of the Pub. Resources Code) does not preclude a lead agency from determining that the resource may be an historical resource as defined in Pub. Resources Code sections 5020.1(j) or 5024.1. In general, a resource that meets any of the four criteria listed in CEQA Guidelines Section 15064.5(a) is considered to be a historical resource unless “the preponderance of evidence demonstrates” that the resource is not historically or culturally significant.”30 801 Bates Avenue does not possess sufficient historic integrity to qualify it as a historic resource, and therefore, the property is not considered a historic resource under the California Environmental Quality Act. 30 Pub. Res. Code SS5024.1, Title 14 CCR, Section 4850 et seq. ---PAGE BREAK--- Historic Resource Technical Report 801 Bates Avenue Final El Cerrito, California September 8, 2010 Page & Turnbull, Inc. - 29 - D. DETERMINATION OF SIGNIFICANT ADVERSE CHANGE UNDER CEQA According to CEQA, a “project with an effect that may cause a substantial adverse change in the significance of an historic resource is a project that may have a significant effect on the environment.”31 Substantial adverse change is defined as: “physical demolition, destruction, relocation, or alteration of the resource or its immediate surroundings such that the significance of an historic resource would be materially impaired.”32 The significance of an historical resource is materially impaired when a project “demolishes or materially alters in an adverse manner those physical characteristics of an historical resource that convey its historical significance” and that justify or account for its inclusion in, or eligibility for inclusion in, the California Register.33 Thus, a project may cause a substantial change in a historic resource but still not have a significant adverse effect on the environment as defined by CEQA as long as the impact of the change on the historic resource is determined to be less-than-significant, negligible, neutral or even beneficial. Since no historic resources, as defined by CEQA, are present on the project site, the proposed project will not cause any significant adverse changes to any qualified historic resources. IX. CONCLUSION Designed in 1932 for Dr. Edward C. Gill, a horticulturalist and professor whose family was well- known locally for their large nursery that was sold to the University of California, 801 Bates Avenue is significant for its connection to Gill. Dr. Gill custom built the house in the Spanish Eclectic style and spent years landscaping the estate and decorating it with his antique follies. However, due to significant alterations and additions, the building does not retain sufficient historic integrity to convey this significance. Therefore, based upon the findings in this report, 801 Bates Avenue is not considered to be a qualified historic resource for the purposes of CEQA. Since no qualified historic resources are present on the project site, the proposed project will not cause any significant adverse changes to an historic resource. 31 CEQA Guidelines subsection 15064.5(b). 32 CEQA Guidelines subsection 15064.5(b)(1). 33 CEQA Guidelines subsection 15064.5(b)(2). ---PAGE BREAK--- Historic Resource Technical Report 801 Bates Avenue Final El Cerrito, California September 8, 2010 Page & Turnbull, Inc. - 30 - X. REFERENCES CITED PUBLISHED WORKS California Office of Historic Preservation, Technical Assistant Series No. 7, How to Nominate a Resource to the California Register of Historic Resources. Sacramento, CA: California Office of State Publishing, 4 September 2001. El Cerrito Historical Society. Images of America: El Cerrito. Charleston, S.C.: Arcadia Publishing, 2005. Emanuels, George. California’s Contra Costa County: An Illustrated History. Fresno, CA: Panorama Books, 1986. Sorensen, Karen and the Albany Historical Society. Images of America: Albany. Charleston, SC: Arcadia Publishing, 2007. Staniford, Edward. El Cerrito: Historical Evolution. El Cerrito, CA: El Cerrito-Kensington Bicentennial Committee, 1976. PUBLIC RECORDS City of El Cerrito Planning Department- building permits and plans El Cerrito Historical Society El Cerrito Public Library NEWSPAPERS AND PERIODICALS Barclay, “El Cerrito ‘Sanctuary’ is Rich in History,” The San Francisco Chronicle (17 May 1953): clipping- page unknown. INTERNET SOURCES Belfils, Mervin. “The Community’s Past- The El Cerrito Historical Society. Website accessed on 5 August 2010 from: http://elcerritowire.com/history/pages/communityspast3.htm. California Death Index, 1940-1997. Website accessed on 16 August 2010 from: www.ancestry.com. El Cerrito Historical Society, “El Cerrito History,” Website accessed on 5 August 2010 from: http://www.el-cerrito.org/community/history.html “Frequently Asked Questions,” The Gill Tract. Website accessed on 5 August 2010 from: http://gilltract.org/Information.html LSA, Report, Experiment Station Research and History- Gill Tract, University of California, Albany, CA (University of California, Berkeley, October 2009) 7. Website accessed on 11 August 2010 from: http://www.cp.berkeley.edu/CP/PEP/History/Reports_and_Studies/Gill_Tract_Experiment_ Station_History.pdf State of California, California Environmental Quality Act, http://ceres.ca.gov/topic/env_law/ceqa/summary.html, accessed 31 August 2007. U.S. Census Records. Website accessed on 9 August 2010 from: Ancestry.com. ---PAGE BREAK--- 1000 Sansome Street, Suite 200 San Francisco, California 94111 [PHONE REDACTED] / [PHONE REDACTED] fax 2401 C Street, Suite B Sacramento, California 95816 [PHONE REDACTED] / [PHONE REDACTED] fax 417 S. Hill Street, Suite 211 Los Angeles, California 90013 [PHONE REDACTED] / [PHONE REDACTED] fax ARCHITECTURE PLANNING & RESEARCH BUILDING TECHNOLOGY www.page-turnbull.com ---PAGE BREAK--- ---PAGE BREAK--- A P P E N D I X D 1 G E O T R I N I T Y G E O T E C H N I C A L R E P O R T ---PAGE BREAK--- ---PAGE BREAK--- Revised Surface Fault Rupture Hazards and Geotechnical Investigation and Response to City of El Cerrito Peer Review Comments 801 Bates Avenue El Cerrito, California GeoTrinity Project No.: GE-2135 June 24, 2009 Prepared For: Mr. Richard Lau 1338 Mandela Parkway Oakland, California 94607 Prepared By: GeoTrinity Consultants, Inc. 7770 Pardee Lane, Suite 101 Oakland, CA 94621 Jerry Yang, PE, GE Patrick L. Drumm, PG, CEG, CHG Project Manager Consulting Engineering Geologist ---PAGE BREAK--- i TABLE OF CONTENTS 1.0 SITE LOCATION AND PROJECT 2.0 SCOPE OF 3.0 SITE 3.1 SURFACE 3.2 REVIEW OF PREVIOUS FAULT EVALUATION 3.3 REVIEW OF AERIAL 3.3.1 Site 3.3.2 3.4 REVIEW OF PUBLISHED GEOLOGIC DATA 3.4.1 Geologic 3.4.2 Overview of the Hayward 3.4.3 Bedrock 3.4.4 Landslides 3.4.5 Seismically Induced 3.5 GEOLOGIC RECONNAISSANCE 3.6 FIELD EXPLORATION 3.6.1 3.6.2 Exposed Faults 3.6.3 Bedrock 3.6.4 3.6.5 Fissure Infill from Ground Rupture 3.6.6 Artificial 3.7 3.8 FAULTING 3.9 SEISMIC 3.9.1 3.9.2 Past and Future Seismicity on the Northern Hayward 3.10 CBC SEISMIC DESIGN CRITERIA 4.0 CONCLUSIONS AND 4.1 HAYWARD FAULT — SURFACE FAULT RUPTURE HAZARD 4.2 SETBACK FROM TOPS OF SLOPES 4.3 TREATMENT OF AREAS UNDERLAIN BY SERPENTINITIC 4.4 TREATMENT OF EXISTING ARTIFICIAL 4.5 UNIFORMITY OF CONDITIONS UNDER 4.6 DIFFICULT EXCAVATION IN 4.7 SOIL 4.8 4.8.1 Clearing and Site 4.8.2 Subgrade Preparation 4.8.3 Fill 4.8.4 Compaction 4.8.5 Utility Trench Backfill 4.8.6 Surface ---PAGE BREAK--- ii 4.8.7 Temporary Slopes and 4.8.8 Permanent Cut and Fill 4.8.9 Constructing During Wet 4.8.10 Excavation Characteristics 4.8.11 Overexcavation of 4.8.12 Guide Specifications 4.9 FOUNDATION 4.9.1 Drilled Piers 4.9.2 Interior 4.10 RETAINING WALLS 4.10.1 Conventional Retaining Walls 4.10.2 Mechanically Stabilized-Earth (MSE) Retaining Walls 4.10.3 Subdrainage for Retaining Walls 4.10.4 Additional Recommendations for Retaining 4.10.5 Lateral Load Resistance 4.10.6 Exterior Concrete 4.11 PRELIMINARY PAVEMENT 4.12 ADDITIONAL 5.0 6.0 AERIAL FIGURES 1 Vicinity Map 2 Geologic Map with Fault Setbacks (in pocket) 3 Earthquake Fault Zones Map 4 Modified Earthquake Fault Zones Map 5 Regional Geologic Map by Graymer (2000) 6 Landslide Map by Alan Kropp & Associates 7 City of El Cerrito Special Study Map APPENDICES A Field Investigation A-1 Figure A-1, Key to Exploratory Trenches and Test Pits Figures A-2 and A-3, Trench Logs by Frank Groffie (in pocket) Figure A-3, Trench Logs by Patrick Drumm (in pocket) Test Pit Logs B Laboratory Investigation B-1 C Guide Specifications – Site Earthwork C-1 ---PAGE BREAK--- iii D Guide Specifications – Asphalt Paving D-1 E Previous Fault Evaluation Reports Data E-1 F GEI Peer Review Letter F-1 ---PAGE BREAK--- Revised GE 2135rpt 801 Bates Avenue, El Cerrito • 7770 Pardee Lane, Suite 101, Oakland, CA 94621 • Phone: [PHONE REDACTED] • Fax: [PHONE REDACTED] 1 1.0 SITE LOCATION AND PROJECT DESCRIPTION This report presents the updated results of our investigation of surface-fault-rupture hazards and geotechnical constraints for the property at 801 Bates Avenue, El Cerrito, California. The vicinity map in Figure 1 shows the site location relative to major regional landmarks. Coordinates at the assumed home site are 37.917 north latitude and 122.287 west longitude (see Figure The site is within the Earthquake Fault Zone for the seismically active Hayward fault (see Figure 3) as defined by the California Geological Survey (State Geologist, 1982). We previously issued a report for the site, dated September 12, 2008, that included our results and findings from the initial exploration program, fault evaluation hazards, and geotechnical recommendations. Our previous report was reviewed by the City of El Cerrito’s peer reviewer, Geotechnical Engineering, Inc., (GEI). In their peer review letter, dated October 16, 2008, GEI had several concerns that focused on the possibility of Holocene activity of faults uncovered in Trenches T-1 and T-2, and on the possibility of creep-prone soils along the descending west- facing slope. The GEI peer review letter is included in Appendix F of this report. Our revised report presented here addresses these concerns and provides updated recommendations based on additional subsurface exploration performed at the site. Therefore, the recommendations of this report supersede those stated in our September 12, 2008 report. For our use we have received a recent site topographic survey map of the property, titled: A portion of Lot 3, “San Pablo Rancho”, filed March 1, 1894, located at 801 Bates Avenue, City of El Cerrito, Contra Costa County, California, dated June 2008, by Moran Engineering. This map shows the existing grades and structures, and was updated in June 2009 to include the surveyed locations of an active fault recently identified in exploratory trenches on the property. We have used this recent survey as a base map for our geologic interpretation of the site (see Figure The property is trapezoidal in shape, with the two longer sides oriented northwest-southeast. The property is approximately 250 feet long, and its width varies from about 140 to 220 feet. Access to the site is from the northeast corner of the property along Bates Avenue that borders the northeast side of the property. Single-family residential lots border the remaining three sides of the property. Based on the information provided to us by your architect, Mr. Peter Strzebniok, we understand that the intent is to demolish the existing house and subdivide the property into four residential lots. The proposed lot lines and locations of proposed residential structures are overlaid on Figure 2 to illustrate the relationship between our recommended fault setback and the proposed site improvements. ---PAGE BREAK--- Revised GE 2135rpt 801 Bates Avenue, El Cerrito • 7770 Pardee Lane, Suite 101, Oakland, CA 94621 • Phone: [PHONE REDACTED] • Fax: [PHONE REDACTED] 2 2.0 SCOPE OF WORK The main objective of our investigation was to investigate the feasibility of subdividing the property, from a geologic and geotechnical viewpoint, into multiple residential lots. Specifically, our purpose was to evaluate the potential for surface fault rupture at the site and to assess geotechnical conditions, including characterizing the foundation soils, and providing recommendations to mitigate identified hazards, and address the geotechnical engineering aspects of the project. Our proposed scope of services, presented in our initial proposal dated June 23, 2008 and in our supplemental proposal dated April 27, 2009, consists of the following. • Reviewing available geologic literature relevant to the property. References cited in this report are listed at the end of the report. • Reviewing available stereoscopic aerial photographs that show the property. Photographs reviewed are listed at the end of the report. • Conducting a site reconnaissance. • Excavating, logging, and sampling five exploratory trenches within the property. Figure 2 shows the trench locations, and Appendix A presents the logs and other subsurface data and describes exploration methods. • Arranging for the geologic reviewer serving on behalf of the City of El Cerrito to observe the open exploratory trenches. • Excavating, logging, and sampling five exploratory test pits in other parts of the property. Figure 2 shows the locations, and Appendix A presents the logs, other subsurface data, and exploration methods. • Performing laboratory tests on soil samples collected from the excavations. Appendix B presents the laboratory test results. • Performing geologic and engineering analysis of data collected. • Developing conclusions and recommendations regarding potential residential construction on the site from the standpoints of the potential hazard of surface fault rupture within the Hayward fault zone and general site geotechnical conditions. • Preparing this investigation report as a summary of our findings, conclusions, and recommendations. Evaluation for presence, type, and extent of non-natural hazardous materials, if any, was beyond our scope of work. This report is a design document that has been prepared in accordance with generally accepted geotechnical engineering and engineering geology practices for the exclusive use and specific application to the proposed improvements. In the event that there are any changes in the nature, design or location of proposed improvements, or if any future additions are planned, the ---PAGE BREAK--- Revised GE 2135rpt 801 Bates Avenue, El Cerrito • 7770 Pardee Lane, Suite 101, Oakland, CA 94621 • Phone: [PHONE REDACTED] • Fax: [PHONE REDACTED] 3 conclusions are recommendations contained in this report shall not be considered valid unless we are contacted in writing, project changes are reviewed by us, and conclusions and recommendations presented in this report are modified or verified in writing. This report does not necessarily represent all of the information that has been communicated by you to us during the course of this engagement and our rendering of professional services for the proposed project. Reliance on this report by parties other than those described above must be at their own risk unless we are first consulted as to the parties’ intended use of this report and only after we obtain the written consent by you to divulge information that may have been communicated by you. The attached exploration logs and related information depict location-specific subsurface conditions encountered during our field investigation. The approximate locations of the test pits and other exposures were visually estimated in the field relative to fences and topographic features, and should be considered accurate only to the degree implied by the method used. The passage of time could result in changes in the subsurface conditions due to environmental changes. ---PAGE BREAK--- Revised GE 2135rpt 801 Bates Avenue, El Cerrito • 7770 Pardee Lane, Suite 101, Oakland, CA 94621 • Phone: [PHONE REDACTED] • Fax: [PHONE REDACTED] 4 3.0 SITE INVESTIGATION 3.1 Surface Conditions The property is dominated by a massive, rounded bedrock ridge exposing basalt outcrops and large basalt boulders. The ridge trends northwest to southeast across the central portion of the site, forming a prominence that gives way to a relatively steep west-facing slope. Within the property, the relief of the west-facing slope ranges from 18 to 36 feet, continuing down the hill to Gelston Place. East of the central ridge, the site is nearly flat and occupied by the access driveway connected to Bates Avenue. Beyond the property to the east, the regional slope ascends to Arlington Boulevard. Elevations within the property range from a high of approximately 687 feet above mean sea level (amsl) near the top of the bedrock ridge to a low of approximately 652 feet amsl in the southwest corner of the property (see Figure The property is occupied by a grand old residence that predates the 1939 aerial photographs. The existing house was constructed on top of the bedrock ridge overlooking San Francisco Bay. At the time of our field work, the stucco on the rear exterior wall of the house had been removed because of reported mildew and extensive moisture damage, and the exterior sheeted with tarps. A large enclosed swimming pool is attached to the back portion of the house and is perched above the descending west-facing slope. However, the pool was empty at the time of our investigation and it appears to have been abandoned. Spacious lawn areas exist along the east and south sides of the house A marble fountain that appears original to the house is located within the south lawn. In contrast, the area along the north side of the house exposes native basalt outcrops and boulders. The west side of the property is a relatively steep slope that descends to residential properties accessed by Gelston Place. The southwest portion of the slope, beginning behind the existing house, is terraced with stone and wood retaining walls and planted with fruit trees. The northwest portion of the slope is not terraced and this area of the property remains relatively undeveloped. The overall slope gradient along the west-facing slope varies from 2:1 to 2.5:1 (1H:1V). The slope face is uneven due to basalt outcrops, boulders, various trees, and terracing. A stone retaining wall from 4 to 8 feet high, constructed of native basalt boulders and likely original to the house, defines the top of slope and supports the downslope edge of the swimming pool and enclosure. Another original stone retaining wall up to 3 feet high exists lower on the slope to form a 4-foot wide walkway between the two walls. Natural basalt outcrops appear to have been incorporated into the construction of both the stone walls. The southwest corner of the property is accesses by a wooden stairway and there are two wood retaining walls up to 3 feet high terracing the lower portion of this part of the slope. A combination chain-link and wood fence exists near the west property boundary (see Figure ---PAGE BREAK--- Revised GE 2135rpt 801 Bates Avenue, El Cerrito • 7770 Pardee Lane, Suite 101, Oakland, CA 94621 • Phone: [PHONE REDACTED] • Fax: [PHONE REDACTED] 5 The southeast side of the property is approximately marked by a chain-link fence. The fence is near the crest of what appears to be a graded fill slope that descends to two neighboring residences below. This slope is up to 9 feet high and has a gradient approaching 1.5:1. 3.2 Review of Previous Fault Evaluation Reports As requested by GEI in their peer review letter (see page 5 of Appendix we have reviewed previous fault evaluation reports in the vicinity of the project site. We reviewed three previous geologic studies performed by various consultants working along the Hayward fault zone and relatively close to the project site. All of these previous studies included fault trenching in an attempt to locate the Hayward fault and assess the potential for surface ground rupture for each site. The locations of these previous studies relative to the project site are shown on Figure 4. A brief summary of findings and conclusions is presented below. Copies of the trench logs and site location maps for each study are included in Appendix E of this report. • ENGEO, Inc., 1978 (AP-838)—This study was performed for a proposed 17-lot residential subdivision. The closest portion of the ENGEO site to the subject property is approximately 200 feet to the east. The study focused on the excavation and geologic logging of a 200-foot long backhoe trench placed perpendicular to the alignment of the Hayward fault zone. The trench was a maximum of approximately 9 feet deep. The trench exposed hard metasedimentary rocks overlain by unconsolidated deposits of clay and silt containing rock fragments. It was concluded that no signs of active faulting had been encountered within the exploratory trench. It is noteworthy to mention that this fault evaluation report was used as part of the 1982 re-zoning of the Hayward Earthquake Fault Zone within the vicinity of the project site that mapped a single questioned fault trace approximately 100 feet to the west (Smith, 1980). • Abel R. Soares and Associates, 1978 (AP-1341)—The purpose of this study was new residential construction on a single lot located at the end of Gelston Place, approximately 70 feet southeast of the project site. A 77-foot long backhoe trench was excavated perpendicular to the alignment of the Hayward fault zone. The trench was 5 to 7 feet deep. Analysis of the trench exposure revealed a west-dipping shear zone that juxtaposed weathered sedimentary rock on the west with decomposed metamorphic rocks on the east. It was concluded that this shear zone was probably not an active creeping trace of the Hayward fault. The construction of the proposed residence was allowed to proceed without any fault setbacks. As discussed further in this report, the northwest projection of the shear zone uncovered by Abel R. Soares and Associates would be in alignment with the major fault identified in our Trenches T-3 and T-5 at the project site. The California Geological Survey shows a single questioned trace of the Hayward fault zone approximately 50 feet east of the Abel R. Soares’ site (State Geologist, 1982). ---PAGE BREAK--- Revised GE 2135rpt 801 Bates Avenue, El Cerrito • 7770 Pardee Lane, Suite 101, Oakland, CA 94621 • Phone: [PHONE REDACTED] • Fax: [PHONE REDACTED] 6 • Darwin Myers Associates, 1988 (AP-2144)—The Darwin Myers investigation was performed in conjunction with exploratory borings by Alan Kropp & Associates, Inc., of Berkeley. The property is approximately 500 feet north of the project site along the south side of Moeser Lane. A single trench 97 feet long and up to 11 feet deep was excavated along the length of the property. Geologic logging of the trench revealed two episodes of debris flow deposits, consisting of sandy clay, pebbly clay, and gravel, separated by a clay- rich paleosol. All units are of unknown ages. Because the various deposits were unbroken, it was concluded that no faults have ruptured across the site since the oldest debris flow was deposited. However, the possibility of future faulting impacting the site could not be ruled out. The California Geological Survey maps a questioned fault trace along the west boundary of this property and another questioned fault trace approximately 250 feet to the east of this property (State Geologist, 1982). 3.3 Review of Aerial Photographs We reviewed the aerial photographs used in the initial investigation and examined additional aerial photographs as part of our current study in an attempt to locate geomorphic anomalies potentially associated with active landsliding and active faulting within or near the project site. For active faults such geomorphic anomalies include narrow valleys, alignment of springs, vegetation changes expressed as lineaments, and relatively linear ground scarps. Similarly, active landsliding can create scarps, hummocky topography, and vegetation anomalies. These geomorphic features can be evaluated by direct field observations, by comparison to mapped fault traces on published maps for the site area, and by logging exploratory excavations at the site. We have reviewed selected vertical stereo pairs of historic aerial photographs of the site vicinity for the years 1939, 1946, 1947, 1949, 1950, 1957, 1959, 1973, and 1980. We focused our analysis on the earliest photographs available to observe the native topography prior to extensive development. The horizontal scales of the photographs analyzed range from 1:7,200 to 1:23,600. A complete list of individual photographs and their sources is provided in the back of this report. 3.3.1 Site Development The existing house was present in the 1939 aerial photographs and it appears on the photographs as part of a large estate perched on top of a prominent knoll overlooking San Francisco Bay. In the 1939 to 1957 aerial photographs reviewed, the subject property appears to encompass more of the lands to the west and south than currently are outlined in the recent topographic map oin Figure 2. Based on our review of aerial photographs from the late 1930s through the late 1950s, the property once included the descending slope down to the present day Gelston Place and Bay Tree Lane, and the area down to and including the terminus of Gelston Place to the south of the current property boundary. The original entrance to the site was via a long winding driveway connected to Terrace Drive, at the current intersection of Terrace Drive and Gelston Place, and located within the same approximate alignment as present day Gelston Place. The property was lined with mature trees on ---PAGE BREAK--- Revised GE 2135rpt 801 Bates Avenue, El Cerrito • 7770 Pardee Lane, Suite 101, Oakland, CA 94621 • Phone: [PHONE REDACTED] • Fax: [PHONE REDACTED] 7 all sides. These early photographs also show the presence of the marble fountain within the south side lawn area. The buried concrete shell uncovered during both phases of exploration at the project site is present on the 1957 and 1959 aerial photographs as a kidney-shaped feature constructed between the existing house and marble fountain. The later aerial photographs reviewed show changes in the west and south property boundaries. The 1959 aerial photographs capture the development of Gelston Place and Bay Tree Lane, without the existing homes. The 1959, 1973, and 1980 show the property boundaries as they exist today. Gelston Place and many of the existing residences along Gelston Place appear on the 1973 aerial photographs. As seen on the 1959 aerial photographs, the entrance to the site was changed from the long winding driveway on the west to the current access off of Bates Avenue at the northeast corner of the property as it currently exists. The existing swimming pool attached to the rear of the house is present on the 1973 and 1980 aerial photographs, but does not appear in the earlier photographs reviewed. 3.3.2 Geomorphology The 1939, 1946, 1947, 1949, and 1950 aerial photographs predate much of the residential development in the vicinity of the project site and provide a glimpse of the natural topography prior to modification by cutting and filling methods. Even though the project site was already developed with the existing house and grounds as seen on the 1939 aerial photographs, the prominent basalt ridge that underlies the central portion of the site can be seen as extending to the northwest into the neighboring residential property, which was undeveloped at this time. The area to the south and east of the property, which now includes Kerr Avenue and Edwin Drive, appears to be involved in a large landslide as identified by an arcuate drainage (interpreted as the lateral margin of a landslide) and generally sunken ground observed on the aerial photographs. The margin of this potential landslide begins approximately 200 feet from the south property boundary. Failure appears to have been downhill to the west, at some distance from the project site (see Figure The 1930s and 1940s aerial photographs also highlight some linear geomorphic anomalies near the project site that we interpret as fault-related. There is a linear valley running northwest- southeast along the east side of Bates Avenue to the north of the project site. The southeast projection of this linear valley would be in alignment with the major fault encountered in our Trenches T-3 and T-5 within the project site. Two more linear features were identified on the early aerial photographs near the site, including one that passes through Roberta Drive to the north of the site and another that crosses Highland Drive to the east of the site. We interpret these three linear geomorphic anomalies as possible fault traces, all located to the east of the project site (see Figure ---PAGE BREAK--- Revised GE 2135rpt 801 Bates Avenue, El Cerrito • 7770 Pardee Lane, Suite 101, Oakland, CA 94621 • Phone: [PHONE REDACTED] • Fax: [PHONE REDACTED] 8 3.4 Review of Published Geologic Data 3.4.1 Geologic Setting The site lies within the San Francisco Bay portion of the Coast Ranges geomorphic province of California, a region characterized by northwest-southeast trending mountain ranges and intervening valleys that parallel the San Andreas family of faults. The site is within the East Bay Hills overlooking the San Francisco Bay. The East Bay Hills in the vicinity of the site are underlain by a variety of bedrock types ranging in age from Late Tertiary to Late Cretaceous. The geologic structure of the site vicinity has been severely complicated by the Hayward fault zone. The bedrock in the vicinity of the site is overlain by a relatively thin veneer of native colluvium and artificial fill from human development. Large bedrock landslides have been mapped in the site vicinity. 3.4.2 Overview of the Hayward Fault The Hayward fault is primarily a northwest-striking dextral-slip (right-lateral) fault. It extends from near Warm Springs, Fremont in the south to San Pablo Bay in the north, a total of approximately 54 miles (Lienkaemper, 1992 and 2006; Radbruch, 1967; and Radbruch-Hall, 1974). The Hayward fault is one of the few faults in the world that exhibits fault-creep1. The Hayward fault creeps along its entire length, with different fault segments creeping at different rates. The average rate of creep is 4 to 5 mm/year (averaged along the length of the fault over several decades). This is about half the average long-term slip rate, which is approximately 9 mm/year. The rest of the slip occurs seismically during earthquakes. The width of the zone of active shearing varies, but is thought to be on the order of 100 to 200 feet (Lettis, 2001; Lienkaemper and others, 2002; and Smith, 1980). North of San Pablo Bay and north of the site, the Hayward fault is thought to step to the right and link with the Rodgers Creek fault. The Rodgers Creek fault extends from San Pablo Bay to near Santa Rosa on the north, a distance of approximately 39 miles. The entire length of the Rodgers Creek-Hayward fault system is approximately 93 miles. The Hayward fault is traditionally divided into two segments, largely based on early paleoseismic assumptions regarding the distribution of large earthquakes along the fault (Lettis, 2001). The southern Hayward fault, identified as the segment extending from near Warm Springs to near Montclair, has a fault length of approximately 33 miles, and is capable of producing a Magnitude 6.7 earthquake. The northern Hayward fault, which is identified as the segment from near Montclair to San Pablo Bay, has a fault length of approximately 22 miles, and is capable of producing a Magnitude 6.4 earthquake. The northern Hayward fault passes along the east side of the project site. The San Francisco Bay area could experience a Magnitude 7.1 event if the entire Hayward fault were to rupture in a single earthquake. Likewise, if the entire Rodgers Creek-Hayward fault system 1 Fault-creep is the slow aseismic movement (without perceived earthquakes) of a fault expressed near the ground surface in minor distress of cultural features. ---PAGE BREAK--- Revised GE 2135rpt 801 Bates Avenue, El Cerrito • 7770 Pardee Lane, Suite 101, Oakland, CA 94621 • Phone: [PHONE REDACTED] • Fax: [PHONE REDACTED] 9 were to rupture in a single event, the resulting earthquake could be as large as a magnitude 7.4 (WGCEP, 2003 and 2008). 3.4.3 Bedrock The various published geologic maps reviewed for this evaluation are not in agreement as to the type of rocks underlying the project site. Early mapping and map compilations by Radbruch and Case (1967), Bishop and others (1973), Dibblee (1980 and 2005), and Ellen and Wentworth (1995) suggested that the site area was underlain by Jurassic-Cretaceous-age Franciscan Assemblage rocks consisting generally of greenstone, sandstone, and chert in a sheared shale matrix. Outcrops of sheared serpentinite were also mapped near the project site. This early geologic mapping of the East Bay Hills was prior to the now widely accepted concept of the Coast Range Ophiolite, a sequence of related rocks forming Jurassic-age ocean crust. Most recent mapping of the site area suggests (see Figure 5) that the bedrock underlying the project site consists of serpentinite and serpentinite-matrix mélange, which are rocks associated with the Coast Range Ophiolite (Graymer ,2000; and Graymer and others, 1994). 3.4.4 Landslides Many landslides have been mapped along the west flank of the East Bay Hills, obscuring traces and inhibiting the surface location of the Hayward fault zone. However, the published maps reviewed for our study vary widely on the actual areal limits of landsliding near the site. The project site is included within a massive landslide complex mapped by the U.S. Geological Survey that extends from near Arlington Boulevard down to Ashbury Avenue encompassing much of the hill portions of El Cerrito and Kensington (Herd, 1978; and Nilsen, 1975). Geologic maps of the site vicinity by Dibblee (1980; and 2005) suggest that the site is included within a massive landslide complex, as approximately mapped by others, and that the upper portion of this landslide complex has since been offset by right-lateral movement along the Hayward fault. A more detained landslide map by Alan Kropp & Associates, Inc. (1995) shows the project site as being located outside of any active or potentially active landslide zone. Kropp maps landslides to the north, approximately 400 feet downslope to the west, and approximately 200 feet to the south of the project site (see Figure Similarly, published geologic maps for the tri-cities area of El Cerrito, Richmond, and San Pablo, also suggest that the project site is outside of any landslide areas with the nearest landslides mapped approximately 200 feet downslope to the west and approximately 200 feet downslope to the south (Bishop and others, 1973). Nonetheless according to the planning map prepared by Harris & Associates (1999) for the City of El Cerrito, the southeast property boundary and the residences along Gelston Place southeast of the project site are mapped within a High Landslide Risk Area (see Figure ---PAGE BREAK--- Revised GE 2135rpt 801 Bates Avenue, El Cerrito • 7770 Pardee Lane, Suite 101, Oakland, CA 94621 • Phone: [PHONE REDACTED] • Fax: [PHONE REDACTED] 10 A more recent landslide publication by the U.S. Geological Survey (Pike and others, 2007) was brought to our attention by GEI in their peer review letter for our initial report (see page 5 of Appendix The publication suggests that the project site is not susceptible to shallow landsliding and has a relatively low susceptibility to deep-seated landsliding. Additionally, there are no undeveloped slopes topographically above the project site that would impact the proposed development (Pike and others, 2007). 3.4.5 Seismically Induced Landslides The California Geological Survey is tasked with mapping hillside areas that have been deemed prone to failure during intense earthquake shaking, as described under the Seismic Hazards Mapping Act of 1990 (Chapter 7.8, Division 2 of the California Public Resources Code). However, they have not yet published maps covering the El Cerrito area. Likewise, the most recent U.S. Geological Survey publication related to seismically induced landsliding for the site area only extends up to the Alameda County boundary and it does not cover El Cerrito (Pike and others, 2007). No landslides triggered by historic earthquakes have been mapped or reported within the site vicinity. According to the U.S. Geological Survey, the closest documented seismically-induced landslide occurred as a result of the 1906 San Francisco Earthquake, approximately 2.5 miles to the northwest of the project site. This landslide was reportedly already moving due to winter rains prior to the earthquake (Youd and Hoose, 1978). 3.5 Geologic Reconnaissance We walked the immediate neighborhood and observed the concrete curbs and sidewalks for signs of distress related to active fault creep along possible fault traces. Possible fault traces were identified from our aerial photographic analysis as discussed in an earlier section. We also conducted limited observations of the perimeter of the property and along the exterior of the existing house for any obvious signs of landsliding. Because Bates Avenue trends in the same approximately orientation as the Hayward fault zone, we were unable to identify any fault creep-related offsets or deflections in the flanking curbs and sidewalks. On the otherhand, Roberta Drive to the east of the project site is approximately perpendicular to the alignment of the Hayward fault zone. One of the suspected fault traces identified on the aerial photographs seems to project through the street. However, Roberta Drive has been coincidently constructed with a bend in the vicinity of the suspected fault trace. The curbs and sidewalk is the vicinity of the bend were observed to be disrupted, but by causes other than active creep, such as tree root damage and downslope creep. The streets in the vicinity of the project site showed no obvious distress attributable to active surface fault offset or landsliding. ---PAGE BREAK--- Revised GE 2135rpt 801 Bates Avenue, El Cerrito • 7770 Pardee Lane, Suite 101, Oakland, CA 94621 • Phone: [PHONE REDACTED] • Fax: [PHONE REDACTED] 11 Our observations of the exterior of the existing residence at 801 Bates Avenue, including driveway, exterior walkways and stairway, and house siding, showed no obvious distress attributable to active surface fault offset or landsliding. Some of the pine trees along the slope in the northwest portion of the property were leaning down the slope and suggest downslope creep of the surface soils. This was one of the concerns that GEI stated in their peer review letter of our initial report (see page 5 of Appendix We anticipate shallow soils on top of massive basalt bedrock ridge in this area that would likely account for the leaning and uprooted trees along the descending slope. We encountered no surficial ground evidence of active landslide masses within the property. 3.6 Field Exploration 3.6.1 Overview Our subsurface exploration at the site was conducted in two separate phases using two different geologists. The initial phase was performed in August 2008 and the subsequence phase of exploration was performed in May 2009, in response to the City of El Cerrito peer review letter by GEI. Some of the information from the initial exploration program has been utilized as part of this revised study while other earlier data was not relied upon to develop our revised recommendations. In the later case, some of the initial exploration was repeated to develop our updated recommendations as stated here. Long trenches were excavated using a backhoe equipped with 24- and 30 inch-wide buckets tipped with rock teeth. Two exploratory trenches, designated Trench T-1 and Trench T-2, were excavated and geologically logged between August 11 and 14, 2008, as part of our initial exploration program at the site. The initial trenches, T-1 and T-2 were logged by Frank Groffie, Certified Engineering Geologist and reviewed in the field by Michael Clark, Certified Engineering Geologist with GEI. Three additional exploratory trenches, designed Trench T-3, T-4, and T-5, were excavated and geologically logged between May 8 and 14, 2009. Both sides of Trench T-3 were logged. The additional trenches, T-3, T-4, and T-5, were logged by Patrick Drumm, Certified Engineering Geologist, and again reviewed in the field by Michael Clark, Certified Engineering Geologist with GEI. A bulk soil sample was collected from Trench T-1 for laboratory testing. Trench depths varied from 4 to 10.5 feet below the ground surface. The initial subsurface program also included excavating four test pits, mainly for geotechnical purposes using the same backhoe equipment. The four exploratory test pits, designated Test Pits TP-1 through TP-4, were excavated between August 11 and 14, 2008, and logged by Frank Groffie, Certified Engineering Geologist. Soil samples were collected from Test Pit TP-3. Test pit depths varied from 2 to 5 feet below the ground surface. ---PAGE BREAK--- Revised GE 2135rpt 801 Bates Avenue, El Cerrito • 7770 Pardee Lane, Suite 101, Oakland, CA 94621 • Phone: [PHONE REDACTED] • Fax: [PHONE REDACTED] 12 A supplemental test pit, TP-5, was excavated by hand using laborers at the northwest corner of the property on May 19, 2009 (see Figure The purpose of this test pit was to investigate the possibility of a mapped fault trace along the lower slopes of the property. TP-5 was logged by Patrick Drumm, Certified Engineering Geologist. The trenches and test pits were backfilled with loosely compacted excavation spoils soon after logging. Some future settling and rutting of the exploration backfills should be expected. If the excavations are located in areas where settlement is not acceptable, these backfill materials should be removed and properly compacted as part of the future development scheme for the project. Figure 2 shows approximate locations of the test pits and trenches. Appendix A presents logs of the trenches and test pits and details regarding the field investigation. Figures A-2 and A-3 show graphic illustrations of the previous trenches logged at the site and Figure A-3 includes graphic illustrations of the most recent excavations logged at the site. Appendix B presents results of our laboratory tests on samples collected. Below is a summary of faults and earth materials encountered in our excavations. 3.6.2 Exposed Faults We placed Trenches T-3 and T-4 near the previously excavated Trenches T-1 and T-2 to investigate the possibility of Holocene seismic activity of the faults logged in the initial phase of investigation at the project site (see Figures A-1 and A-2) as requested by GEI in their peer review letter (see page 5 on Appendix Our more recent trench exposures revealed a major east-dipping shear zone in Trench T-3, and a minor east-dipping shear in Trench T-4. Both of these structures were encountered in the previous trench exploration program at the approximate locations shown in the original figures of the previous report. Major Shear: The major shear zone in Trench T-3 was marked on the west end by a sheared clayey gouge that varied from 6 to 24 inches thick. The width of the shear zone is in excess of 25 feet and continued beyond our exploratory Trench T-3 to the east. The major shear zone generally juxtaposed basalt on the west from metasedimentary rocks, sheared serpentinite, and crushed rocky zones on the east. The strike of the clayey gouge ranged from N20W to N24W with subhorizontal slickensides. The dip of the gouge was approximately 22 degrees to the northeast in the near surface. After we graphically plotted the field data from both sides of Trench T-3 on the trench logs, we realized that the top of bedrock surface across the fault was vertically offset approximately 1 foot (up on the east side). The upward projection of the clayey gouge zone visibly truncated and over- rode colluvial units as seen in the north side and south side of the Trench T-3 log, respectively. This situation, as graphically illustrated on the Trench T-3 logs, has implications for Holocene-age ---PAGE BREAK--- Revised GE 2135rpt 801 Bates Avenue, El Cerrito • 7770 Pardee Lane, Suite 101, Oakland, CA 94621 • Phone: [PHONE REDACTED] • Fax: [PHONE REDACTED] 13 seismic activity. Therefore, we have interpreted the clayey gouge associated shear zone as a major surface trace of the Hayward fault zone and have established an appropriate construction setback for future residential development as mentioned later in this report. Trench T-5 was excavated in the driveway to locate the northwest projection of the major east- dipping shear as it crossed the property. Based on the near surface exposure of the major shear zone logged in Trench T-3, we identified the uppermost portion of the major shear zone at the Trench T-5 location. Both the T-3 and T-5 locations of the major shear zone were surveyed and made part of the development plan. Minor Shear: A minor shear was also encountered in Trench T-4 in approximately the same location as in the previous exploration This minor shear consisted of an approximate 1 to 2 inch wide shear zone separating basalt on the west from weathered serpentinite on the east. The strike ranged from N28W to N35W and dipped 20 to 35 degrees to the northeast. We interpret this minor shear as part of the overall Hayward fault zone, but as a structure that is stepping over to the right to joint the major shear zone mentioned above. We have not established a construction setback from this minor shear, but rather we recommend not locating a structure overtop of this feature. 3.6.3 Bedrock We encountered bedrock in all of the explorations logged within the project site. Generally, three types of bedrock underlies the property, including basalt (map symbol “KJb” on Figure weathered serpentinite (map symbol “KJsp” on Figure and various metamorphic rocks (map symbol “KJm” on Figure The dominate rock type underlying the project site is basalt. The existing house was constructed on a basalt ridge that appears to be bounded along the east by the major shear zone encountered in Trenches T-1, T-3, and T-5. The exception is at the extreme southeast end of the property where the minor shear was encountered in Trenches T-2 and T-4 placing basalt on the west against weathered serpentinite on the east. There is a wedge of weathered serpentinite between the major and minor shears in the southeast portion of the site. Undifferentiated metamorphic rocks underlie the property along the east side of the major shear zone as encountered in Trench T-3. Basalt: Some of the basalt (trench log symbol on Figure A-3) encountered in the exploratory excavations and observed in outcrops within the site had been metamorphosed to greenstone. Generally, the basalt and greenstone encountered was hard to very hard and moderately fractured with abundant iron staining along fracture surfaces. The prominent joint orientation throughout the site appears to be striking N03E to N16E and dipping 69 to 70 degrees southeast. The backhoe equipment used to excavate Trench T-3 and Test Pit TP-4 encountered refusal on the basalt. Some areas of the project site may be difficult to excavate for proposed grades and future foundations. ---PAGE BREAK--- Revised GE 2135rpt 801 Bates Avenue, El Cerrito • 7770 Pardee Lane, Suite 101, Oakland, CA 94621 • Phone: [PHONE REDACTED] • Fax: [PHONE REDACTED] 14 Serpentinite: Weathered serpentinite bedrock (trench log symbol “E2” on Figure A-3) was observed in Trenches T-2 and T-4 to be fault bounded between the major and minor shear zones in the southeast portion of the property. The serpentinite was completely weathered to a soil consistency of blue-gray silty clay, and found to be in a moist to moist and soft condition. The presence of serpentinite has special ramifications with regard to naturally occurring asbestos. Refer to Section 4 for conclusions and recommendations. Metamorphic Rocks: The undifferentiated metamorphic rocks (trench log symbols “E1”, and on Figure A-3) encountered only along the east side of the major shear zone contained a variety of rock types, including quartzite, calcium-rich silicates, and sheared serpentinite. In Trench T-3 due to the complexity of the sheared rocks, we logged these materials into broad packages based on general lithology, color, degree of shearing, and overall hardness. The metasedimentary rocks of Unit encapsulated the serpentinite with boulders Unit “E1” on both sides of Trench T-3. Units and exhibited soil-like properties and were distinguished based generally on color and sandiness. Other Rocks: We should note that another rock type, argillite, was encountered in Trenches T-3 and T-5 in contact with basalt on the west side of the major shear zone. The amount of argillite, a low grade metamorphic clay-rich rock, exposed in the trench (trench log symbol was too minor to map as a separate geologic unit on the Geologic Map of Figure 2. The relationship between the basalt and the argillite is likely fault-related, however, we were unable to locate a continuous structure that could be labeled a fault. The bedrock surface across the contact between basalt and argillite was not vertically offset as it was for the major shear zone. So therefore, we believe that this suspected fault trace is pre-Holocene in age. 3.6.4 Colluvium Colluvium is an accumulation of native soils generated from the weathering of the underlying deposits and bedrock. Colluvium generally mantles most of the bedrock within the project site from a few inches to a few feet as encountered in the exploratory excavations (trench log symbols “b1”, “b2”, “b3”, “b4”, and The exception is where bedrock is exposed at the ground surface, such as in the various outcrops mapped at the site (see Figure We logged five separate types of colluvium with the exploratory excavations at the site, based on lithologic charateristics. Unit “b1”, a sandy clay deposit with pebble size basalt rock fragments, was the most pervasive colluvial deposit logged at the site. This unit was likely derived from erosion of the massive basalt ridge that comprises the central portion of the site. Unit “b1” was up to 2 feet thick in Trenches T-3 and T-4. Unit “b2” logged in Test Pit TP-5 contain boulders of basalt in addition to smaller basalt fragments. ---PAGE BREAK--- Revised GE 2135rpt 801 Bates Avenue, El Cerrito • 7770 Pardee Lane, Suite 101, Oakland, CA 94621 • Phone: [PHONE REDACTED] • Fax: [PHONE REDACTED] 15 The only difference between colluvial Units “b1” and “b3” was that “b2” contained argillite rock fragments and not basalt fragments. This distinction became important in locating the uppermost portion of the major shear zone in Trench T-5 Unit “b3” appears to have been displaced or truncated by fault movements. A rocky colluvial deposit, Unit “b4”, was encountered only on the west side of the major shear zone in Trenches T-3 and T-4. The unit was consistently up to 6 inches thick in Trench T-3 and thickened to up to 18 inches in Trench T-4. This deposit contained abundant and characteristic cobble size rock fragments of basalt, presumably from the adjacent massive basalt ridge that makes up the central portion of the project site. The rocky colluvium was underlain by Unit “b5”, a loose clayey sand deposit encountered only in Trench T-4. Both Units “b4” and “b5” thickened as they approached the minor shear in Trench T-4. Both colluvial units did not cross the minor shear and they were not logged above the basalt bedrock west of the minor shear in Trench T-4 (at least in the available trench exposure that was somewhat affected by the backfill of the old Trench T-4). Unit ‘b5” varied from two inches at the east end of Trench T-4 to 18 inches at minor shear at the west end of Trench T-4. Unit “b1” was sampled in Test Pit TP-3 for laboratory analysis during the initial exploration of the site. Laboratory test results suggest a moderately plastic and moderately expansive native soil with a plasticity index of 47. See Appendix B for test results. 3.6.5 Fissure Infill from Ground Rupture In Trench T-5, we encountered a loose pocket of clayey sand and pebble to cobble size rock fragments (trench log symbol on Figure A-3) between the argillite and basalt bedrock units, west of the major shear zone. Unit was characterized with abundant voids and could be easily excavated into a large cavity between hard rock layers. The overall appearance was chaotic, however we observed some subhorizontal layers within the unit. Because of the association with the surface expression of the major shear zone, we have interpreted this unit as a fissure infill related ground rupture during an earthquake. 3.6.6 Artificial Fill The property has been modified by filling for the initial development of the existing house and grounds. This appears to have been confined to the southeast portion of the site occupied the south side yard and the end of the asphalt driveway. Much of this area is underlain by a 2-foot thick layer of fill soils generally consisting of clayey sand and rock fragments (trench log symbol The approximate aerial limits of this fill are shown on Figure 2 (map symbol Several abandoned metal pipes were encountered near the base of the fill layer as shown on Figure A-3. ---PAGE BREAK--- Revised GE 2135rpt 801 Bates Avenue, El Cerrito • 7770 Pardee Lane, Suite 101, Oakland, CA 94621 • Phone: [PHONE REDACTED] • Fax: [PHONE REDACTED] 16 It appears that the fill was placed in a natural southwest-draining swale in the southeast portion of the project site between the minor and major shears. As explored in Trench T-4, the fill thickened to approximately 3 feet in this area to maintain the level grade of the south side yard. There is a possibility the slope leading down from the south property boundary to the residence below may be a graded fill slope that marks the old swale. As mentioned before this possible fill slope is up to 9 feet high. Sometime later in the 1960s or 1970s, based on our review of aerial photographs, a concrete- lined pond or swimming pool, located between the existing house and marble fountain, was filled in and the south side yard again re-leveled. The west ends of Trenches T-1 and T-3 encountered concrete demolition debris that was apparently used to fill in the old pond/pool shell. This debris was in the form of stacked concrete slabs ranging from 4 to 9 inches in thickness and measuring up to 4 feet across in the longest dimension (trench symbol The approximate areal limits of this buried concrete debris are outlined on Figure 2 (map symbol “Qfd”). Refer to Section 4 for conclusions and recommendations regarding treatment of fill. 3.7 Groundwater No groundwater or seepages were encountered in our trenches or test pits at the locations and depths excavated. We should note at that groundwater levels fluctuate seasonally and during periods of prolonged precipitation. However, groundwater is not anticipated to impact the proposed development for the project site. 3.8 Faulting The property is located within the Earthquake Fault Zone for the Hayward fault as defined by the Alquist-Priolo Earthquake Fault Zone Act of 1972 (Hart and Bryant, 1997). According to the California Geological Survey (see Figure the Hayward fault near the site is mapped as two questioned traces, approximately 100 and 500 feet to the east-northeast within an Earthquake Fault Zone up to 1,500 feet wide (State Geologist, 1982). The initial Alquist-Priolo Earthquake Fault Zone map for the site area, prior to the revised 1982 version map currently used for the site area, depicts the Hayward fault zone as a single dashed trace passing near the intersection of Roberta Drive and Bates Avenue (Smith, 1980; and State Geologist, 1974). The initial 1974 version of the Earthquake Fault Zone map for the area is in agreement with the major shear zone we uncovered in Trenches T-3 and T-5 within the project site. Early fault location maps published by the U.S. Geological Survey show the Hayward fault as a single trace passing near the intersection of Roberta Drive and Bates Avenue. These same maps show multiple fault traces related to the Hayward zone to the northwest and southeast of the project ---PAGE BREAK--- Revised GE 2135rpt 801 Bates Avenue, El Cerrito • 7770 Pardee Lane, Suite 101, Oakland, CA 94621 • Phone: [PHONE REDACTED] • Fax: [PHONE REDACTED] 17 site (Dibblee, 1980; Radbruch, 1967; Radbruch-Hall, 1974; and Radbruch and Case, 1967). Published geologic maps for the tri-cities area of El Cerrito, Richmond, and San Pablo also depict the Hayward fault zone near the project site as a single dashed trace passing through the intersection of Roberta Drive and Bates Avenue, and expanding into multiple traces to the northwest and southeast of the property (Bishop and others, 1973). As mentioned earlier, the single fault trace mapped by various geologists near the intersection of Roberta Drive and Bates Avenue is in alignment with the major shear zone logged in our Trenches T-3 and T-5 within the project site. More recent fault maps by the U.S. Geological Survey suggest that the project site is between two fault traces. One fault trace is mapped as passing 200 feet northeast of the property and the other fault trace is mapped as passing through the west portion of the property roughly parallel to the southwest property boundary (Lienkaemper, 1992; and 2006). The explore the presence of this westernmost fault trace passing across the lower slopes of the project site, we excavated and geologically logged Test Pit TP-5 at the extreme northwest corner of the property. We found no evidence of faulting in Test Pit TP-5 and observed no signs of active faulting passing through the massive basalt ridge linking the test pit to the upper slopes of the property. We should also note that other geologic maps published by the U.S. Geological Survey map a trace of the Hayward fault zone passing through the intersection of Roberta Drive and Bates Avenue, which is in alignment with the major shear zone uncovered in trenches during our exploration at the project site. This mapping also shows additional fault traces approximately 800 and 1,200 feet to the east, and approximately 1,000 feet to the west of the property (Graymer, 2000; and Graymer and others, 1994) Refer to Section 4, below, for recommendations for locating residential structures with regard to the potential hazard of surface fault rupture. 3.9 Seismic Setting 3.9.1 Overview The project site is located within the seismically active San Francisco Bay area where small earthquakes (M<4) are frequent, moderate earthquakes (M 4–6) are sometimes felt, and large earthquake (M>6) occur, but are rare. For example, during the preparation of this report a Magnitude 3.2 earthquake (Event ID#: nc40237749) occurred approximately 0.8 mile to the northwest of the project site. No damages were reported at the site (http://quake.wr.usgs.gov/recenteqs/Quakes/nc40237749.htm). Various faults of the San Andreas fault system dominate the seismic setting of the site. Table 1, below, lists the seven known active faults believed to present the highest potential levels of ground shaking at the site, their distances from the site, their potential maximum moment-magnitude ---PAGE BREAK--- Revised GE 2135rpt 801 Bates Avenue, El Cerrito • 7770 Pardee Lane, Suite 101, Oakland, CA 94621 • Phone: [PHONE REDACTED] • Fax: [PHONE REDACTED] 18 earthquakes, and their fault class under the California Building Code (CBC) system. Fault locations relative to the site were derived from information tabulated by Cao and others (2003), and earthquake magnitudes and fault classes were taken directly from Cao and others (2003). Table 1. Significant faults in the region. Fault name Distance to fault (mi) Distance to fault (km) Direction to fault MCE magnitude (Mw) CBC fault class Hayward, northern 0.1 0.1 SW 6.7 A Hayward, southern 4.7 7.5 SE 6.4 A San Andreas, N. Coast south 17.7 28.4 W 7.4 A Rodgers Creek 14.2 22.9 NW 7.0 A Mt. Diablo thrust 13.6 21.9 E 6.6 B San Andreas, Peninsula 17.7 28.5 SW 7.1 A Calaveras, northern 14.5 23.3 E 7.4 A Earthquake intensities will vary throughout the vicinity and the region, depending on magnitude of the earthquake, distance from the site to the causative fault, and types of materials underlying the site. It should be assumed the site will be subjected to at least one moderate to severe earthquake that will cause strong ground shaking during the design life of the improvements. 3.9.2 Past and Future Seismicity on the Northern Hayward Fault No large earthquakes (M>6) are known to have occurred along the northern Hayward fault during the last 230 years (historic time). Prior to the publication by Toppozada and Borchardt (1998), the 1836 Earthquake (M 6.8) was believed to have occurred along the northern Hayward fault. However, the location of 1836 event has been reevaluated and placed east of Monterey Bay, south of the San Francisco Bay Area, although the epicenter has not been determined. The timing of surface-rupturing earthquakes on the northern Hayward fault in Holocene time is not as well constrained as those on the southern Hayward fault. The recurrence interval for large earthquake on the southern Hayward fault is 140 + 30 years (HPEG, 1999; and Lettis, 2001). Therefore, given that the last major earthquake on the southern Hayward fault occurred in 1868, the next large earthquake along the southern Hayward fault is expected to be within the next 30 years. The most recent large earthquake on the northern Hayward fault was sometime between AD 1640 and AD 1776. This information is based on evidence recovered from backhoe trenches during a 1998 paleoseismic study at the Mira Vista Golf and Country Club in El Cerrito along the east side of Arlington Boulevard approximately 1 mile northwest of the property. This means that 230 to 360 years have elapsed since a major earthquake on the northern Hayward fault. The study concluded ---PAGE BREAK--- Revised GE 2135rpt 801 Bates Avenue, El Cerrito • 7770 Pardee Lane, Suite 101, Oakland, CA 94621 • Phone: [PHONE REDACTED] • Fax: [PHONE REDACTED] 19 that at least four and possibly as many as seven earthquakes have occurred at the Mira Vista site during a 1,630 – 2,130 year interval. This suggests a recurrence interval of 270 to 710 years for large earthquakes along the northern Hayward fault (HPEG, 1999; and Lettis, 2001). A comparison of the paleoseismic records of large earthquakes along both the southern and northern Hayward faults show that some past events overlap within the same time interval. This overlap could be interpreted to mean that both fault segments may have ruptured during a past earthquake, the most recent event being between AD 1027 and AD 1479. Alternatively, a review of the paleoseismic records also suggests that some past events are constrained to the northern Hayward fault, the last of which occurred between 230 and 360 years ago. There is no evidence to suggest that the 1868 Hayward earthquake rupture continued beyond the north end of the southern Hayward fault (HPEG, 1999; Lettis, 2001; and Lienkaemper and Baldwin, 2008) Although the seismic record of earthquakes on the northern segment of the Hayward fault is unclear, there is a 63% chance that a large earthquake (M>6.7) will occur in the San Francisco Bay area within the next 30 years. There is a 31% chance that this earthquake will occur somewhere on the Rodgers Creek-Hayward fault system (WGCEP, 2008). 3.10 CBC Seismic Design Criteria Based on 2007 California Building Code (CBC) criteria, factors S1, Ss, Fa, and Fv are required to determine the code design response spectra for the site. The soil profile at the site is determined to be type Sc, corresponding to approximately soft bedrock. For seismic design using the 2007 CBC according to the 2003 NEHRP Recommended Provisions for Seismic Regulations for New Buildings and Structures, the site has SD1 = 0.686, SDs = 1.351, Fa =1.0, Fb =1.3, approximately. ---PAGE BREAK--- Revised GE 2135rpt 801 Bates Avenue, El Cerrito • 7770 Pardee Lane, Suite 101, Oakland, CA 94621 • Phone: [PHONE REDACTED] • Fax: [PHONE REDACTED] 20 4.0 CONCLUSIONS AND RECOMMENDATIONS We conclude that the central bedrock ridge portion of the property at 801 Bates Avenue is suitable for the proposed residential construction from an engineering geologic and geotechnical engineering standpoint. We recommend that all new residential construction at the site be located within the basalt bedrock as outlined on Figure 2. Residential construction may consist of a new residence at the location of the existing residence or subdividing the property into four new residential properties as shown on Figure 2. Conclusions and recommendations presented in this report should be incorporated into any layouts of building footprints and into other aspects of project design and construction to minimize possible foundation and related problems. Based on subsurface conditions described in Section 3 of this report, the primary geologic and geotechnical considerations for residential development or redevelopment of the site consist of potential presence of active traces of the Hayward fault, setbacks from tops of slopes, presence of serpentinite with naturally occurring asbestos, requiring special treatment during grading, presence of existing fill, requiring overexcavation and replacement, potential need to create uniform conditions (likely including rock and colluvium overexcavation) under future foundation footings, potentially difficult excavation, and shrink-swell potential of surficial clay. Discussions of each of these seven site-specific considerations are presented below. Other geotechnical concerns addressed in this report include foundation considerations, retaining wall design, preliminary pavement design, and seismic design criteria. 4.1 Hayward Fault — Surface Fault Rupture Hazard As discussed earlier, in Section 3, the property is within the Earthquake Fault Zone for the Hayward fault (State Geologist, 1982). Section 3 presents details regarding our updated findings from site- specific fault investigations and locations of suspected fault traces near the project site. The Hayward fault is one of the more active and hazardous geologic features in the San Francisco Bay area, if not the United States. Ground surface fault rupture associated with a large, damaging earthquake on the south segment of the Hayward fault in 1868 has been well documented (Youd and Hoose, 1978). Based on findings from our subsurface exploration and research, we conclude that the predominate shear zone encountered in Trench T-3 and also located in Trenches T-1 and T-5 is a major surface trace of the Hayward fault zone. This location of a major trace of the Hayward fault zone is corroborated by several published maps (Bishop and others, 1973; Dibblee, 2005; Dibblee, 1980; Graymer, 2000; Graymer and others, 1994; Radbruch, 1967; Radbruch-Hall, 1974; Radbruch and Case, 1967; and State Geologist, 1974) and supported by an independent fault evaluation study for a nearby residential property to the southeast of the project site (Abel R. Soares and Associates, ---PAGE BREAK--- Revised GE 2135rpt 801 Bates Avenue, El Cerrito • 7770 Pardee Lane, Suite 101, Oakland, CA 94621 • Phone: [PHONE REDACTED] • Fax: [PHONE REDACTED] 21 1978). Future development at the site is restricted because of this major shear zone and it has implications for future seismic hazards relative to the property (see Figure Our analysis of the collected data indicates that the colluvial deposits between the minor and major shears (Units “b4” and “b5” in addition to Unit “b1”on Trench T-4) and the placement of thicker artificial (Unit “a1”) to maintain level grades as logged in Trench T-2 and T-4 suggests the present of a buried swale at the southeast portion of the project site. We propose that the minor shear encountered in Trenches T-2 and T-4 is stepping over to the right (east) to join the major shear encountered in Trenches T-1, T-3, and T-5. There is no evidence to suggest that the minor shear passes through the massive basalt outcrop that makes up the central portion of the project site. This “stepover” fault geometry creates a down-dropped basin between the two shears that would appear as a structurally-controlled swale widening to the southwest. We recommend that any future residential construction within the project site be restricted to reduce the potential for surface fault rupture hazard from the major shear encountered in Trenches T-1, T-3, and T-5. Therefore, we have established a 25-foot horizontal setback from the surface projection of the west edge of the major shear zone located in the southeast portion of the property to reduce the potential for surface fault rupture for structures designed for human occupation as shown on Figure 2. Although no horizontal setback has been established, we also recommend that proposed structures in the southeast portion of the site be located off of the trace of the minor shear encountered in Trenches T-2 and T-4. According to the Alquist-Priolo Earthquake Fault Zoning Act, any proposed structure for human occupation2 should be set back from the surface trace of an active fault. While there is no minimum setback distance, the State of California suggests that a 50-foot horizontal setback may suffice unless determined otherwise by geologic evidence and confirmed by an independent geologic reviewer. Buildings for human occupancy include the main house and structurally attached garages, plus any detached garages with living quarters.3 Foundation footprints for such structures may be taken to mean “the building” for purposes of these recommendations. Excluded from the foundation footprint and setback criteria are roof overhangs, carports, decks, and porches. Other structures may be located within the 25-foot setback zone, such as stand alone garages without living quarters that are structurally detached from the main house, gazebos, pools, spas, driveways, and walkways, realizing that these structures may be severely damaged by surface fault rupture during an earthquake. 2 Structures designed for human occupation are defined as those having a human occupancy rate of more than 2,000 person- hours per year (Appendix B, California Code of Regulations, Title 14, Division 3. Plus mother-in-law quarters, detached garages with living quarters above, and other outbuildings and similar structures that could be occupied by persons for 2,000 person-hours per year or more. ---PAGE BREAK--- Revised GE 2135rpt 801 Bates Avenue, El Cerrito • 7770 Pardee Lane, Suite 101, Oakland, CA 94621 • Phone: [PHONE REDACTED] • Fax: [PHONE REDACTED] 22 4.2 Setback from tops of slopes On a preliminary basis, site improvements should be setback a minimum of approximately 10 feet from tops of existing slopes to reduce the possibility of downslope creep. Alternatively, proposed structures located within 10 feet of the tops of slopes may have deepened foundation systems designed to reduce downslope creep. The existing tops of slopes are located along the southeast and southwest sides of the property. We can provide detailed recommendations for setbacks from tops of slopes once detailed topography and project site plans and grading plans are provided. 4.3 Treatment of Areas Underlain by Serpentinitic Material Serpentinite is a rock composed of one or more serpentine minerals. One serpentine mineral is are tiny and have a needle-like shape. is one source of naturally occurring asbestos. In one rock hand specimen obtained from Trench T-2, we observed a vein of approximately 1/8 inch thick. This indicates the serpentinite underlying the property may be assumed to contain on the order of 1 or a few percent which is typical for serpentinite in California. Figure 2 shows where we observed and anticipate bedrock composed of serpentinite; see map symbol “KJsp”. Section 3.3.1, above, presents additional discussion of locations where we observed, and where we extrapolate, serpentinite to be present. Asbestos in a construction environment tends to be a potential health hazard when the affected material is mechanically disturbed and exposed and airborne dust is a result. For that reason, watering, use of respirators, and similar practices and controls are typical and should be available and used as needed. In onsite areas where serpentinite will be excavated or graded, earthwork contractor(s) working on any residential project on the property should, at a minimum, implement appropriate earthwork, material-handling, and personal safety measures to minimize inhalation of potential airborne asbestos fibers by onsite workers and use measures to minimize movement of airborne dust offsite downwind or to other neighboring properties. The contractor(s) should consider using the services of an industrial hygienist to monitor worker and neighborhood health safety regarding this issue during earthwork. In areas of building pads underlain by areas of serpentinite bedrock, the bedrock should be overexcavated to a depth of 2 feet below finished subgrade and replaced with nonserpentinitic “cover” material. (Areas underlain by future driveway and exterior slabs need not receive such overexcavation and replacement.) The basalt bedrock onsite would be appropriate material for use as nonserpentinitic cover fill material. If serpentinitic material is exported from the site, recipients of such material should be made aware that the material they are receiving contains asbestos. Field personnel from GeoTrinity Consultants should observe the earthwork to provide ---PAGE BREAK--- Revised GE 2135rpt 801 Bates Avenue, El Cerrito • 7770 Pardee Lane, Suite 101, Oakland, CA 94621 • Phone: [PHONE REDACTED] • Fax: [PHONE REDACTED] 23 field recommendations regarding exposure of serpentinite and its overexcavation and replacement with nonserpentinitic cover material. 4.4 Treatment of Existing Artificial Fill Existing artificial fill, where it would not be removed by design grading for future improvements, should be removed and replaced with engineered fill where future structures, slabs, and driveway would be located. Laterally, such overexcavation and replacement should extend outward and below an imaginary 2H:1V plane extending from bottoms of footings, slabs, and pavements. See Figure 2 and Appendix A for approximate locations and depths of existing fill, where known based on our observations. Additional minor deposits, zones, or lenses of existing fill could be present. The deposit of fill designated “Qfd” in Figure 2 is laden with concrete demolition debris. In its present condition much or all of this fill material is likely unsuitable for use as material for new engineered fill for future grading. With special processing some unknown fraction (or none) may be reused. The chunks of concrete may be reused as material for new engineered fill, provided that the chunks are broken down to pieces 6 inches or smaller before placement in new fill, as recommended below under the heading Earthwork, subsection Fill Material. Otherwise, the larger chunks will need to be hauled offsite. Other deleterious components of this fill deposit may come to light during grading, requiring special treatment, separation, and/or offhaul. Aside from the previous paragraph, in general, the existing onsite fill may be reused as material for new engineered fill. The existing fill was observed to contain no significant amounts of foreign material that would preclude use for new engineered fill. However, unknown pockets of buried fill with excessive deleterious material could come to light during grading, rendering an affected portion of fill unsuitable for reuse as engineered fill and requiring that the affected fill be hauled off site. Where deleterious debris is minor and can be removed by hand, this may be done subject to approval by our site representative during construction. 4.5 Uniformity of Conditions Under Foundations Given that shallow (perimeter spread footing) foundations may be appropriate for future residential construction onsite, conditions under foundations will need to be relatively uniform. These recommendations are provided to minimize differential settlement of residential structures. Given that colluvium on site is variable, patchy, potentially expansive, and associated with adversely sloping ground (and thus subject to downslope creep), residential foundation footings should not be underlain by colluvium. Colluvium should be removed and replaced with new engineered fill under foundation footings. Laterally, such overexcavation and replacement should ---PAGE BREAK--- Revised GE 2135rpt 801 Bates Avenue, El Cerrito • 7770 Pardee Lane, Suite 101, Oakland, CA 94621 • Phone: [PHONE REDACTED] • Fax: [PHONE REDACTED] 24 extend outward and below an imaginary 2H:1V plane extending from bottoms of footings. Appendix A and Figure 2 can provide limited information on colluvium locations, where we explored. Existing fill in areas of improvements should be removed and replaced with new engineered fill, as recommended in Section 4.4, above. All foundation elements of any one residence should bear on only one type of geologic/geotechnical material to a minimum depth of 2 feet below bottoms of footings. In other words, residential foundation footings for any single residence should bear on either all bedrock or a minimum 2-ft-thick layer of new engineered fill under footing bottoms (then underlain by bedrock). To achieve Condition above, it could be necessary to overexcavate bedrock across much of a building foundation footprint to the required depth and replace with new engineered fill. Laterally, such overexcavation and replacement should extend outward and below an imaginary 2H:1V plane extending from bottoms of footings. Driveways, walkways, and patios may be underlain by different subgrade geologic/geotechnical materials, provided that existing fill is removed and replaced with new engineered fill, recommendations presented elsewhere in this report are followed, and future management of effects of potential minor differential movement of underlying soil as a maintenance issue by future property owners will be acceptable. Supplemental geotechnical subgrade/foundation recommendations for carports, decks, porches, gazebos, pools, spas, and similar ancillary improvements could be needed. We can provide supplemental geotechnical recommendations for such improvements as needed, upon request. 4.6 Difficult Excavation in Rock We recommend that all proposed residential construction at the project site be located on basalt bedrock. Excavation into the basalt could be difficult in places and could result in oversize boulders. See Sections 4.8.11 and 4.8.12, below, for detailed discussions and recommendations. 4.7 Soil Expansion Laboratory tests indicate the surficial soil on site is high expansion potential. Expansive soil and bedrock can undergo significant volume change with changes in moisture content. They shrink and harden when dried and expand and soften when wetted. To reduce the potential for damage to proposed improvements, we recommend that slabs-on-grade, if desired, have sufficient reinforcement and be supported on a layer of nonexpansive fill and that all structure foundation footings extend below the zone of seasonal moisture fluctuation. ---PAGE BREAK--- Revised GE 2135rpt 801 Bates Avenue, El Cerrito • 7770 Pardee Lane, Suite 101, Oakland, CA 94621 • Phone: [PHONE REDACTED] • Fax: [PHONE REDACTED] 25 Along with the foundation design and general grading practices, it is important to manage surface water runoff on each building pad. This should include drainage improvements to provide positive drainage away from building, and collect and channel surface water runoff to suitable outlets. In addition, prudent landscaping and irrigation are important for managing the moisture changes around structures. Detailed grading and foundation recommendations addressing these concerns are presented in Sections 4.8 and 4.9 of this report. 4.8 Earthwork 4.8.1 Clearing and Site Preparation Sites for future residential construction should be cleared of obstructions, including trees, brush, associated root systems, existing foundations and subsurface structures, rock walls, driveway pavement, turf, and the like. Holes resulting from removal of underground obstructions should be cleared and backfilled with suitable material compacted as recommended below under the heading Compaction. Loose backfill in our 2008 exploratory trenches and test pits, where not removed by the proposed grading and where located within areas of planned improvements, should be removed and replaced with engineered fill. Figure 2 presents limited information regarding locations; only locations of the central, deepest parts of trenches and test pits are shown. Appendix A presents additional details on the extents of excavation dimensions: depths and widths. Backfill in exploratory trenches and test pits should be removed and replaced with the understanding that the all such exploratory features deeper than 5 feet included benching for excavation safety: i.e., widths may be approximately 8 feet. 4.8.2 Subgrade Preparation After the clearing and stripping, exposed areas to receive structural fill, slabs-on-grade, or pavements should be scarified to a depth of 6 inches, moisture conditioned to above optimum water content, and compacted to the requirements for structural fill. In order to achieve satisfactory compaction in the subgrade and fill materials, it may be necessary to adjust the water content at the time of construction. This may require that water be added to soil that is too dry, or that scarification and aeration be performed in soil that is too wet. 4.8.3 Fill Material On-site soil having an organic content of less than 3 percent by volume can be used as fill. See Section 4.4, above, for discussion of avoiding reuse of existing debris-laden fill. Fill placed at the site, including on-site soil, should not contain rocks or lumps larger than 6 inches in greatest ---PAGE BREAK--- Revised GE 2135rpt 801 Bates Avenue, El Cerrito • 7770 Pardee Lane, Suite 101, Oakland, CA 94621 • Phone: [PHONE REDACTED] • Fax: [PHONE REDACTED] 26 dimension, with not more than 15 percent larger than 2½ inches. In addition, imported fill, if any, should be predominantly granular, with a plasticity index of 14 or less. 4.8.4 Compaction New engineered fill, as well as scarified surface soil in those areas to receive fill or slabs-on-grade, should be compacted to at least 90 percent relative compaction as determined by ASTM Test Designation D1557, latest edition, at a moisture content near the laboratory optimum, except for the native expansive clays. Where fill zones are more than 5 feet thick, the portion deeper than (below) a depth of 5 feet should be compacted to at least 93 percent relative compaction. Fill should be placed in lifts no greater than 8 inches in uncompacted thickness. Each successive lift should be firm and nonyielding under the weight of the construction equipment. Fill material composed predominantly of native expansive clay or claystone should be compacted to 87 to 92 percent relative compaction at a moisture content at least 3 percent over optimum. In pavement areas, the upper 6 inches of subgrade and full depth of aggregate base should be compacted to at least 95 percent relative compaction (ASTM D1557, latest edition). Aggregate base and all import soil should be compacted at a moisture content near the laboratory optimum. 4.8.5 Utility Trench Backfill Bedding and shading materials to be used around underground utility pipes should be predominantly granular and should be placed and compacted in accordance with the project specifications, local requirements, or governing jurisdiction. General trench backfill used over shading should be placed and compacted in accordance with local requirements or the recommendations contained in this section, whichever is more stringent. Materials encountered during this investigation may be used as general fill over shading materials provided they conform to our recommendations in Section 4.8.3 – Fill Material. General fill should be placed in lifts not exceeding 8 inches in uncompacted thickness and should be compacted to at least 90 percent relative compaction (ASTM D1557, latest edition) by mechanical means only; jetting of trench backfill is not recommended. However, thicker lifts can be used, provided the method of compaction is approved by the geotechnical engineer, and the required minimum degree of compaction is achieved. The upper 12 inches of general fill in building pad and pavement areas subject to wheel loads should be compacted to at least 95 percent relative compaction. Where utility trenches backfilled with sand enter building pads, the trenches should be backfilled by an impermeable plug at the exterior wall foundation. The plugs can be composed of compacted clayey soil, compacted bentonite, or a bentonite-cement or sand-cement slurry ---PAGE BREAK--- Revised GE 2135rpt 801 Bates Avenue, El Cerrito • 7770 Pardee Lane, Suite 101, Oakland, CA 94621 • Phone: [PHONE REDACTED] • Fax: [PHONE REDACTED] 27 mixture. The plugs should be at least 2 feet thick and should extend at least 2 feet beyond the edges and bottom of the trench. The plug should also extend up to within 1 foot of the lowest adjacent grade. All utility trenches that extend below curbs and gutters should also be plugged as described above. The plug should be located below the curb and gutter. 4.8.6 Surface Drainage Positive surface gradients should be provided adjacent to the structures to direct surface water away from foundations and slabs toward suitable discharge facilities. Similarly, roof downspouts should be connected to solid collector pipes that discharge to appropriate facilities. Ponding of surface water should not be allowed adjacent to the structures or on pavements. 4.8.7 Temporary Slopes and Shoring The grading/earthwork contractor should be familiar with applicable local, state, and federal regulations, including the current OSHA Excavation and Trench Safety Standards. The following information is presented for preliminary design purposes and is intended to indicate subsurface conditions in order to appropriately design and construct temporary construction slopes. Temporary cut slopes should not exceed an inclination of ½H:1V. It is important to note that the soil to be excavated may vary significantly across the site. The contractor should verify that similar conditions exist throughout the proposed area of excavations. If different subsurface conditions are encountered at the time of construction, we recommend that we be contacted immediately to evaluate the conditions encountered. The contractor’s “responsible person,” as defined in 29 CFR Part 1926, should evaluate the soil exposed in the excavations as part of the contractor’s safety procedures. If an excavation, including trenches, would be extended to a depth of more than 20 feet, it will be necessary to have the side slopes designed by a registered civil engineer. As an alternative to temporary construction slopes, vertical excavations can be temporarily shored using braced or cantilevered sheet pile shoring schemes for placement of structures. The shoring should be adequately rigid to minimize damage to the adjacent ground surface. The contractor or specialty subcontractor should be responsible for the design of the temporary shoring in accordance with applicable regulatory requirements. We recommend that GTC review any temporary shoring plans. In addition, we recommend that the geotechnical engineer observe the installation of the temporary shoring system. ---PAGE BREAK--- Revised GE 2135rpt 801 Bates Avenue, El Cerrito • 7770 Pardee Lane, Suite 101, Oakland, CA 94621 • Phone: [PHONE REDACTED] • Fax: [PHONE REDACTED] 28 4.8.8 Permanent Cut and Fill Slopes Permanent future graded slopes, assuming proposed slopes 8 feet tall or less, may be constructed at gradients of • 2H:1V or gentler where bedrock is exposed • 2H:1V or gentler where future engineered fill is exposed • 3½ :1V where (native) colluvium is exposed Cut slopes exposing bedrock or colluvium should be observed by an engineering geologist in the field during construction to evaluate conditions exposed against the conclusions, recommendations, and assumptions developed with our investigation. We recommend that erosion control measures be installed on all exposed slopes to minimize erosion on slope surfaces. At a minimum, fast-growing vegetation hydroseed) should be applied to slopes before the first rainy season. A positive surface gradient of at least 2 percent away from tops of slopes should be provided to direct surface runoff away from the slopes and toward suitable collection and discharge facilities. Fill slopes should generally be constructed in accordance with the recommendations shown in Figure 3. Keyways are recommended for all fill slopes placed on natural ground having a gradient of 7H:1V or steeper. The front of the keyway should be located where an imaginary extension of the fill slope extends downward through the surficial soil and “catches” top of bedrock. Generally, keyway depth at the front should be at least 3 feet deep into bedrock, and keyway width should be at least 15 feet or one-half of the fill slope height, whichever is greater. The base of the keyway should slope toward a subdrain at a gradient of about 2 percent. The subdrain should be placed at the rear of the keyway. Horizontal benches should be excavated through colluvial soil into bedrock as fill is placed during slope construction. Subdrains should consist of perforated pipe surrounded by free draining, uniformly graded, ½ to ¾-inch crushed gravel wrapped in filter fabric such as Mirafi 140N or equivalent. The filter fabric should overlap approximately 12 inches or more at joints. Alternatively, Caltrans Class 2 Permeable Material may be substituted for the crushed gravel and filter fabric. The subdrain pipe should consist of perforated, minimum 4-inch-diam., rigid ABS (SDR-35) or PVC A-2000 or equivalent pipe. Perforations should face down. Subdrain trenches should be at least 18 inches wide and 4 feet deep. Subdrains may also be placed against a backcut rather than in a trench; regardless, subdrain volume should be a minimum of ⅔ c.y. per lineal yard of subdrain line. Lateral subdrains should be connected to a solid collector pipe with a minimum diameter of 6 inches. The collector pipe should be connected to a drainage outlet that is able to transmit the collected water to a proper drainage facility. Upstream ends of subdrain pipelines should be ---PAGE BREAK--- Revised GE 2135rpt 801 Bates Avenue, El Cerrito • 7770 Pardee Lane, Suite 101, Oakland, CA 94621 • Phone: [PHONE REDACTED] • Fax: [PHONE REDACTED] 29 provided with clean-out facilities. Clean-outs should be based on the reach of rotary cleaning system and the restrictions of pipe bends. Subdrain lines should be surveyed during construction in order that their locations will be documented for later use in maintenance, troubleshooting, and later construction activities. Permanent graded slopes will, nevertheless, be subject to minor surficial sloughing and erosion requiring periodic maintenance. 4.8.9 Constructing During Wet Weather If construction proceeds during or shortly after wet weather, the moisture content of on-site soil could be unfavorably above optimum. Consequently, subgrade preparation, placement and/or reworking of on-site soil as structural fill might not be possible at that time. The soil should then be allowed to dry enough so that the moisture content falls within a workable range, around optimum. Alternatively, wet-weather construction recommendations can be provided by the geotechnical engineer in the field at the time of construction, if appropriate. 4.8.10 Excavation Characteristics A few zones a few feet across in Trench T-1 were difficult to excavate using a backhoe, due to very strong basalt bedrock with a fracture spacing on the order of 1 ft. Otherwise, bedrock in Trenches T-1 and T-2 and Test Pit TP-2 was generally excavatable using a backhoe. These locations were in the southeast (rear) part of the site. (Refer to Appendix A for locations and for depths below present ground surface.) Bedrock in Test Pit TP-4 was shallow and difficult to excavate using a backhoe, due to strong bedrock with a fracture spacing on the order of 1½ ft. Outcrops of hard bedrock are evident near the entrance to the existing residence. These locations are in the northwest part of the site. We expect excavation of bedrock will be generally feasible using conventional earthmoving machinery, e.g., Caterpillar D-9 or equivalent, in the southeast part of the site. Excavation in bedrock could be extremely slow in the central (existing homesite) and northwest portions of the site. Excavation in bedrock on site could result in oversize boulders that may require hauling offsite. Extremely slow and difficult drilling/excavation could be encountered in small auxiliary excavations in bedrock, such as for some footing trenches, utility trenches, and auxiliary deck) foundation pier holes. See next section for a suggested remediation. Future potential earthwork, foundation, excavation, and utility contractors, should, in addition to reviewing this report, visit the site to observe surface rock conditions at the site. ---PAGE BREAK--- Revised GE 2135rpt 801 Bates Avenue, El Cerrito • 7770 Pardee Lane, Suite 101, Oakland, CA 94621 • Phone: [PHONE REDACTED] • Fax: [PHONE REDACTED] 30 4.8.11 Overexcavation of Bedrock In order to make trenching for foundations and utilities feasible or practical, consideration should be given to overexcavating bedrock from building pads and replacing with new engineered fill. Such excavation would extend down to the depths of bottoms of foundation footings and utility trenches. 4.8.12 Guide Specifications All earthwork should be performed in accordance with the recommendations presented under Guide Specifications - Site Earthwork, in Appendix C. These specifications are general in nature and the final specifications should incorporate all recommendations presented in this report. 4.9 Foundation Support 4.9.1 Drilled Piers We recommend that the proposed development be entirely supported on drilled, cast-in-place, straight shaft piers that develop their load carrying capacity by side resistance between the pier concrete and the surrounding materials underlying the site. The piers should have a minimum diameter of 16 inches, and a minimum center-to-center spacing of three times the shaft diameter. Pier and grade beam reinforcing should be based on structural requirements. The actual design depth of the piers should be determined using an averaged allowable side resistance of 700 pounds per square foot (psf) for dead plus live loads, with a one-third increase for all loads including wind or seismic. Eighty percent of side resistance can be used to resist uplift. The piers should be at least 15 feet in length or 10 feet into the competent bedrocks, whichever is greater. The strength of upper two foot of soils along pier shaft should be neglected in design, unless the adjacent grade is completely covered by concrete or pavement. Grade beams should be designed to span between piers. The bottoms of the pier excavations should be relatively dry, and free of all loose cuttings or slough prior to placing reinforcing steel and concrete. Any accumulated water in pier excavations should be removed prior to placing concrete. Structural loads were not available for our review at the time of our investigation. Based on the maximum allowable side resistance and end bearing recommended above, we estimate that post- construction differential movement between adjacent columns will be no greater than ½ inch. We should be retained to review the final foundation plans and structural loads to verify the above settlement estimates. ---PAGE BREAK--- Revised GE 2135rpt 801 Bates Avenue, El Cerrito • 7770 Pardee Lane, Suite 101, Oakland, CA 94621 • Phone: [PHONE REDACTED] • Fax: [PHONE REDACTED] 31 4.9.2 Interior Slabs-on-Grade We recommend that interior slabs-on-grade, if used, be supported on a minimum of 12 inches of nonexpansive compacted fill. Alternatively, if the slab is reinforced with a minimum of #4 bars spaced 18 inches apart on-center both ways for shrinkage control, the slab could be supported on 6 inches of nonexpansive fill. However, for either alternative, slab reinforcing should be provided in accordance with the anticipated use and loading of the slab. Slab-on-grade subgrade surfaces should be proof-rolled to provide a smooth, unyielding surface for slab support. It may be possible, with selective grading, to obtain nonexpansive fill material from on site, in which case laboratory testing by our firm during construction would be needed to verify the nonexpansive characteristics of the proposed fill material. Below interior slabs-on-grade in living spaces, a moisture barrier should be provided between the slab and subgrade. We recommend that such a moisture barrier consist of 4 inches of free draining gravel covered with a 10-mil-thick impermeable membrane Moistop®) placed between the subgrade soil and the slab. The membrane should be covered with 2 inches of sand for protection during construction. The sand should be moistened just before placing the concrete. Where a moisture barrier is used, the recommended nonexpansive fill thickness may be reduced by 6 inches. If a wall or footing is not present next to the slab to cut off exterior water entry into the moisture barrier, then a minimum 12-inch-wide concrete barrier or “thickened edge” that is supported directly on the subgrade should be provided at the perimeter of the slab. Concrete slabs retain moisture and often take many months to dry. We recommend that carpets that allow air to pass through them be used over concrete floor slabs. If vinyl or wood floor products are to be used, the concrete floor slab should be given sufficient time to air dry before the flooring product is installed. Alternatively, a floor sealant could be applied over the concrete to minimize slab moisture from entering the flooring product. Tests or other recommendations provided by the manufacturer of the flooring should be followed. 4.10 Retaining Walls Retaining walls can be supported on footing foundations. Foundations should bear either on engineered fill or bedrock. Foundations may also bear on native soil but only where the ground slopes away at a gradient less than 7H:1V and the exposed native soil is judged competent by our representative in the field at the time of construction. Where unacceptable colluvium subgrade conditions are exposed in footing excavations, either the retaining wall should be extended below grade in order to bear on bedrock or the colluvium should be removed and replaced with engineered fill. See the section titled Permanent Cut and Fill Slopes for recommendations for placing engineered fill on slopes. ---PAGE BREAK--- Revised GE 2135rpt 801 Bates Avenue, El Cerrito • 7770 Pardee Lane, Suite 101, Oakland, CA 94621 • Phone: [PHONE REDACTED] • Fax: [PHONE REDACTED] 32 Retaining walls may be of the conventional cantilever type or MSE type. Recommendations for both are presented below. Another type of retaining wall, the soil-nail type, may also be used, and may have applicability in support of cut slopes. We can develop geotechnical design parameters for soil-nail walls upon request. 4.10.1 Conventional Retaining Walls We recommend the criteria presented in Table 2, below, be incorporated into design of conventional cantilever retaining walls: Table 2. Geotechnical design criteria for conventional cantilever retaining walls. Active equivalent fluid pressure Level backfill 3H:1V backfill 2H:1V backfill 45 pounds per cubic foot (pcf) 55 pcf 65 pcf Passive equivalent fluid pressure acting against twice the projected area of the individual pier shafts be used for design 350 pcf Minimum grade beam depth 18 inches below lowest adjacent grade Minimum grade beam width 16 inches The above recommended lateral pressures do not include surcharges. Therefore, the designer should include appropriate surcharge loads in retaining wall designs. 4.10.2 Mechanically Stabilized-Earth (MSE) Retaining Walls We recommend the criteria presented in Table 3, below, be incorporated into design of mechanically stabilized-earth (MSE), or modular-block, retaining walls: Table 3. Geotechnical design criteria for MSE retaining walls Recommended values Parameter Bedrock Competent soil, fill Reinforced fill Unit weight NA 135 pcf ---PAGE BREAK--- Revised GE 2135rpt 801 Bates Avenue, El Cerrito • 7770 Pardee Lane, Suite 101, Oakland, CA 94621 • Phone: [PHONE REDACTED] • Fax: [PHONE REDACTED] 33 Friction angle Cohesion 35 degrees 200 psf Retained material Unit weight Friction angle Cohesion 140 pcf 37 degrees 0 psf 135 pcf 33 degrees 200 psf Foundation material Unit weight Friction angle Cohesion 140 pcf 37 degrees 0 psf 135 pcf 33 degrees 200 psf Allowable bearing pressure 5,000 psf 3,000 psf Notes: Allowable bearing pressures may be increased by one- third for seismic and wind loads. Allowable bearing pressures should be 3,000 psf and 2,000 psf, respectively, for footings placed on bedrock and engineered fill with slopes greater than 3H:1V. The bases of the modular blocks should be at least 6 inches (level ground) and 16 inches (sloped ground) below lowest adjacent finished grade. The walls at the site will be subjected to hydrostatic pressures, and should be designed for such conditions, unless they are provided with rear drainage. Rear drainage should be installed behind the modular blocks to prevent the buildup of hydrostatic pressure. Subdrain pipes should be set at the level of the base of the wall’s gravel pad. For modular-block retaining walls more than 6 feet tall, the permeable material blanket should be placed behind the geogrid. 4.10.3 Subdrainage for Retaining Walls Our recommended wall design parameters given above assume walls are fully backdrained to prevent build-up of hydrostatic pressures. Adequate drainage may be provided by a subdrain system positioned behind the walls. This system should consist of a 4-inch minimum diameter, perforated pipe placed near the base of the wall (perforations placed downward). The pipe should be surrounded with Class 2 Permeable Material of Caltrans Standard Specifications, latest edition. The permeable backfill should extend at least one foot out from the wall and to within one foot of the finished grade. Alternatively, ½-inch to ¾-inch crushed rock may be used in place of the Class 2 Permeable Material, provided the crushed rock and pipe are enclosed in filter fabric, such as Mirafi 140N or equivalent. The upper one foot of wall backfill should consist of ---PAGE BREAK--- Revised GE 2135rpt 801 Bates Avenue, El Cerrito • 7770 Pardee Lane, Suite 101, Oakland, CA 94621 • Phone: [PHONE REDACTED] • Fax: [PHONE REDACTED] 34 relatively impervious compacted on-site clayey soil. The subdrain outlet should be connected to a free-draining outlet or sump. In addition, damp-proofing of the walls should be included in areas where wall moisture would be undesirable. Enkadrain®, Miradrain®, or other geotechnical drainage panel product acceptable to GTC may be used for wall drainage as an alternative to Class 2 Permeable Material or drain rock and filter fabric. The drainage panel should be connected to the perforated pipe at the base of the wall. 4.10.4 Additional Recommendations for Retaining Walls A pseudostatic seismic coefficient, k, of 0.15 is applicable for seismic loading design of retaining walls. When using this value of k, a wall should be designed to withstand the seismic loading with a pseudostatic factor of safety of at least 1.15. Construction of walls likely will involve steep temporary backcuts. Such cuts are anticipated to have limited stand-up time. The actual stand-up time is unknown, and will be affected by the height of cut, type of exposed material, weather conditions, vibrations, and other variables. Generally, a concrete-lined ditch should be provided directly behind the tops of the walls to collect and transmit surface water runoff from the slopes above. 4.10.5 Lateral Load Resistance Lateral load resistance for shallow footings can be developed by friction between the foundation bottom and the supporting subgrade. A resistance coefficient of 0.30 is considered applicable. As an alternative, a passive resistance equal to an equivalent fluid weighing 350 pounds per cubic foot acting against the vertical face of the foundations could be used. If foundations are poured neat against the soil, then friction and passive resistance can be used in combination. The uppermost one foot of soil should be neglected for passive pressure design, unless the adjacent grade is directly overlain by slab or pavement. Lateral load resistance for drilled-pier foundations for decks can be developed by mobilizing passive resistance against the drilled pier shafts. We recommend a passive resistance equal to an equivalent fluid weighing 300 pounds per cubic foot acting against twice the projected area of the individual pier shafts be used for design. The uppermost 5 feet of soil should be neglected for passive pressure design, unless the adjacent grade is directly overlain by slab or pavement. 4.10.6 Exterior Concrete Slabs To minimize issues related to potential differential movements of near-surface soils, which are heterogeneous, consideration should be given to reinforcing exterior concrete slabs, walkways, driveways, and curb and gutter with steel bars in lieu of wire mesh. Number 4 bars spaced 18 ---PAGE BREAK--- Revised GE 2135rpt 801 Bates Avenue, El Cerrito • 7770 Pardee Lane, Suite 101, Oakland, CA 94621 • Phone: [PHONE REDACTED] • Fax: [PHONE REDACTED] 35 inches apart center-to-center each way could be used. Dowels should be provided at all expansion and cold joints. Although walkways that are adequately reinforced will still crack, trip hazards requiring replacement of the slabs would be minimized. Alternatively, a flexible flatwork system, such as interlocking paving stones could be used for walkways and driveways. Paving stones can be releveled or replaced as part of maintenance if future settlement occurs. Adequate clearance should be provided between the exterior slabs and building elements that overhang these slabs, such as window sills or doors that open outward. This may be accomplished by using a strip of 30-pound felt divider material between the slab edges and the adjacent structures. Walkways should be supported directly on properly prepared native soils or compacted fills. Eliminating rock base beneath slabs will minimize the potential for migration of landscape irrigation water into walkway subgrade. A day or two before placing concrete, subgrade soils should be soaked to increase their moisture content to at least 3 to 5 percent above laboratory optimum moisture (ASTM D-1557-91).The water content of subgrade soils should be verified by field testing by the engineer prior to placing concrete. 4.11 Preliminary Pavement Sections The following recommendations for preliminary asphalt concrete pavement sections are intended as a conceptual guide for planning only. Pavement analyses are based on an assumed R (resistance) value of 5, which we expect to be representative of portions of final pavement subgrade materials, Caltrans’s Design Method for Flexible Pavement, and traffic indices (TIs), which are indications of traffic load frequency and intensity. We assume that TIs to be assigned will include provisions for heavy truck traffic related to construction activities. Table 4, below, presents our preliminary recommend pavement sections. Table 4. Preliminary recommended pavement sections. Thickness (inches) Traffic index (TI) Asphalt concrete Type B Caltrans Class 2 aggregate base 4 2½ 8 4½ 2½ 10 5 3 10 5½ 3 12 6 3½ 13 6½ 4 14 7 4 16 ---PAGE BREAK--- Revised GE 2135rpt 801 Bates Avenue, El Cerrito • 7770 Pardee Lane, Suite 101, Oakland, CA 94621 • Phone: [PHONE REDACTED] • Fax: [PHONE REDACTED] 36 7½ 4½ 17 8 4½ 19 8½ 5 20 Before subgrade preparation, all utility trench backfill should be properly placed and compacted. Subgrade soil should be rolled to at least 95 percent relative compaction to provide a smooth, unyielding surface. Areas of subgrade that show yielding under construction traffic or proof rolling should be overexcavated and replaced with compacted, unyielding material aggregate base) as recommended by the geotechnical engineer. Subgrade soil should be maintained in a moist and compacted condition until covered with the complete pavement section. Caltrans Class 2 aggregate base should conform to the requirements in Section 26 of Standard Specifications, by Caltrans, dated July 1995. The aggregate base should be placed in thin lifts in a manner to prevent segregation, uniformly moisture conditioned, and compacted to at least 95 percent relative compaction to provide a smooth, unyielding surface. Relative compaction refers to the in-place dry density of soil expressed as a percentage of the maximum dry density of the same soil, as determined by the ASTM D Test Method 1557-00. Since subsurface conditions on this project vary from strong bedrock to relatively weak, expansive clay, we recommend that at least one sample be collected from the rough driveway subgrades during site grading. R-value tests should be performed on the samples. Final pavement section recommendations should be made on the basis of the test results. In order to prevent the subgrade soil and aggregate base from being saturated by infiltrating irrigation water or rainwater, roadway underdrains should be installed along uphill curbs or edges of pavement along future driveways. 4.12 Additional Services At the time of our services, no grading plans or site construction plans had been developed. Additional geotechnical engineering services may be needed as designs for site development become available. Additional geologic/geotechnical engineering services will be needed for design and construction of the project. These include plan review, responses to plan-check comments, and construction observation. We recommend that our firm review the final design and specifications to check that the earthwork and foundation recommendations presented in this report have been properly ---PAGE BREAK--- Revised GE 2135rpt 801 Bates Avenue, El Cerrito • 7770 Pardee Lane, Suite 101, Oakland, CA 94621 • Phone: [PHONE REDACTED] • Fax: [PHONE REDACTED] 37 interpreted and implemented in the design and specifications. We can assume no responsibility for misinterpretation of our recommendations if we do not review the plans and specifications. The analysis, designs, opinions, and recommendations submitted in this report are based in part on the data obtained from the trenches and test pits and observed surface conditions existing when our services were performed. Variations of subsurface conditions from those analyzed or characterized in the report are possible as may become evident during construction. In that event it may be advisable to revisit certain analyses or assumptions. We recommend that our firm be retained to provide geotechnical services during site preparation and foundation installation, to observe compliance with the design concepts, specifications and recommendations presented in this report. Our presence will also allow us to modify design if unanticipated subsurface conditions are encountered. ---PAGE BREAK--- Revised GE 2135rpt 801 Bates Avenue, El Cerrito • 7770 Pardee Lane, Suite 101, Oakland, CA 94621 • Phone: [PHONE REDACTED] • Fax: [PHONE REDACTED] 38 5.0 REFERENCES Abel R. Soares and Associates, 1978, Geotechnical Investigation, Lot 12 Tract 2577, Gelston Place, El Cerrito, California: Consultant’s Unpublished Technical Report, Project No. 48-5, 7 4 figs. [AP-1341] Alan Kropp & Associates, Inc., 1995 (latest revision in March), Landslides of the Berkeley Hills: Consultant’s Landslide Map, map scale 1:24,000. Bishop, C.C., Knox, R.D., Chapman, R.H., Rodgers, D.A., and Chase, G.B., 1973, Geological and Geophysical Investigations for Tri-Cities Seismic Safety and Environmental Resources Study: California Geological Survey Preliminary Report 19; Prepared in Cooperation with the Cities of El Cerrito, Richmond, and San Pablo, 10 pls., map scale 1:24,000. California Geological Survey, 1997, Guidelines for Evaluating and Mitigating Seismic Hazards in California: Special Publication 117, 74 p. Cao, Bryant, W.A., Rwoshandel, Branum, and Wills, C.J., 2003, The Revised 2002 California Probabilistic Seismic Hazard Maps, June 2003: California Geological Survey, 11 3 appendices, www.consrv.ca.gov/cgs/rghm/psha/fault_parameters/htm/index.htm. Darwin Myers Associates, 1988, Supplement Fault Hazard Assessment, Inserto Property, APN #505-292-032, Bates Avenue, El Cerrito, California: Consultant’s Unpublished Technical Report, Project No. 20032.88, Dated July 22, 1988, 5 7 figs. [AP-2144] Davis, J.L., 1982, Richmond revised official map: California Division of Mines and Geology special studies zones map. Dibblee, T.W., Jr., 2005, Geologic Map of the Richmond Quadrangle, Contra Costa & Alameda Counties, California: Dibblee Geology Center Map #DF-147, map scale 1:24,000. Dibblee, T.W., Jr., 1980, Preliminary Geologic Map of the Richmond Quadrangle, Alameda and Contra Costa Counties, California: U.S. Geological Survey Open-File Report 80-1100, map scale 1:24,000. ENGEO, Inc., 1978, Alquist-Priolo Seismic Hazards Investigation, 3 Acre Lot, Arlington Boulevard, Kensington, California: Consultant’s Unpublished Technical Report, Project No. N8-1252-B1, Dated June 12, 1978, 12 7 figs. [AP-838] Ellen, S.D., and Wentworth, C.M., 1995, Hillside Materials and Slopes of the San Francisco Bay Region, California: U.S. Geological Survey Professional Paper 1357, 215 7 pls. ---PAGE BREAK--- Revised GE 2135rpt 801 Bates Avenue, El Cerrito • 7770 Pardee Lane, Suite 101, Oakland, CA 94621 • Phone: [PHONE REDACTED] • Fax: [PHONE REDACTED] 39 Geotechnical Engineering, Inc., (GEI), 2008, Peer Review of Surface-Fault-Rupture-Hazards and Geotechnical Investigation Report, Planned Subdivision, 801 Bates Avenue, El Cerrito, California: City of El Cerrito Peer Review Letter, Dated October 16, 2008, Job No. 41236 EC, 10 p. Graymer, R.W., 2000, Geologic map and map database of the Oakland metropolitan area, Alameda, Contra Costa, and San Francisco Counties, California: U.S. Geological Survey Open-File Report 96-252, map scale 1:50,000. Graymer, R.W., Jones, D.L., and Brabb, E.E., 1994, Preliminary Geologic Map Emphasizing Bedrock Formations in Contra Costa County, California: A Digital Database: U.S. Geological Survey Open-File Report 94-622, map scale 1:75,000. Harris & Associates, 1999: Special Study Map: Official Map of Geologic Hazards, City of El Cerrito Building Services Division, map scale 1:4,800. Hart, E.W., and Bryant, W.A., 1997 (revised), Fault-Rupture Hazard Zones in California: California Geological Survey Special Publication 42, 38 p. Hayward Fault Paleoearthquake Group (HPEG), 1999, Timing of Paleoearthquakes on the Northern Hayward Fault – Preliminary Evidence in El Cerrito, California: U.S. Geological Survey Open-File Report 99-318, 12 6 figs. Herd, 1978, Map of Quaternary Faulting along the Northern Hayward Fault Zone: U.S. Geological Survey Open-File Report 78-308, Sheet 2 of 8, map scale 1:24,000. Jennings, C.W., compiler, 1994, Fault Activity Map of California and Adjacent Areas with Locations and Ages of Recent Volcanic Eruptions: California Geological Survey, Geologic Data Map No. 6, map scale 1:750,000. Lettis, W.R., 2001, Late Holocene Behavior and Seismogenic Potential of the Hayward-Rodgers Creek Fault System in the San Francisco Bay Area, California: in Ferriz, and Anderson, eds., Engineering Geology Practice in Northern California: California Geological Survey Bulletin 201 and Association of Engineering Geologists Special Publication 12, 167-177 pp. Lienkaemper, J.J., 2006, Digital Database of Recently Active Traces of the Hayward Fault, California: U.S. Geological Survey Data Series 177 (http://pubs.usgs.gov/ds/2006/177/). Lienkaemper, J.J., 1992, Map of Recently Active Fault Traces of the Hayward fault, Alameda and Contra Costa Counties, California: U.S. Geological Survey Miscellaneous Field Studies Map MF-2196, map scale 1:24,000. Lienkaemper, J.J., and Baldwin, 2008, Mira Vista Golf and Country Club, El Cerrito, California: in Lienkaemper, J.J., and Baldwin, Field Trip Guide, Third Conference on Earthquake Hazards in the Eastern San Francisco Bay Area, Northern Hayward Fault Trip, October 26, 2008: U.S. Geological Survey and William Lettis & Associates, Inc. ---PAGE BREAK--- Revised GE 2135rpt 801 Bates Avenue, El Cerrito • 7770 Pardee Lane, Suite 101, Oakland, CA 94621 • Phone: [PHONE REDACTED] • Fax: [PHONE REDACTED] 40 Lienkaemper, J.J., Dawson, T.E., Personius, S.F., Seitz, G.G., Reidy, L.M., and Schwartz, D.P., 2002 (draft submitted to BSSA), A Record of Large Earthquakes on the Southern Hayward Fault for the Past 500 Years: in Graymer, and Lienkaemper, leaders, Hayward Fault/Tule Pond Trench Site Field Trip: Northern California Geological Society, October 13, 2002, 1-30 pp Nilsen, T.H., 1975, Preliminary Photointerpretation Map of Landslide and Other Surficial Deposits of Richmond 7½’ Quadrangle, Contra Costa and Alameda Counties, California: U.S. Geological Survey Open-File Map 75-277-47, map scale 1:24,000. Pike, R.J., and Graymer, R.W., eds., 2007, Multiple Landslide-Hazard Scenarios Modeled for the Oakland-Berkeley Area, Northern California: U.S. Geological Survey Scientific Investigations Report 2007-5196, 51 p. Radbruch, D.H., and Case, J.E., 1967, Preliminary Geologic Map and Engineering Geologic Information, Oakland and Vicinity, California: U.S. Geological Survey Open-File Report 67- 183, map scale 1:24,000. Radbruch, D.H., 1967, Approximate Location of Fault Traces and Historic Surface Ruptures within the Hayward Fault Zone between San Pablo and Warm Springs, California: U.S. Geological Survey Miscellaneous Geologic Investigations Map I-522, map scale 1:62,500. Radbruch-Hall, E.H., 1974, Map Showing Recently Active Breaks along the Hayward Fault Zone and the Southern Part of the Calaveras Fault Zone, California: U.S. Geological Survey Miscellaneous Investigations Series Map I-813, map scale 1:24,000. Smith, T.C., 1980, Fault Evaluation Report FER-101: Unpublished Report, California Geological Survey, Dated November 5, 1980, 30 5 pls. State Geologist, 1982, Revised Official Map of the Alquist-Priolo Earthquake Fault Zones, Richmond Quadrangle: California Geological Survey Official Map, Released January 1, 1982, map scale 1:24,000. State Geologist, 1974, Official Map of the Alquist-Priolo Earthquake Fault Zones, Richmond Quadrangle: California Geological Survey Official Map, Released July 1, 1974, map scale 1:24,000. Working Group on California Earthquake Probabilities (WGCEP), 2008, The Uniform California Earthquake Rupture Forecast, Version 2 (UCERF U.S. Geological Survey Open File Report 2007-1437; California Geological Survey Special Report 203; Southern California Earthquake Center Contribution #1138. Working Group on California Earthquake Probabilities (WGCEP), 2003, Earthquake Probabilities in the San Francisco Bay Region: 2002 to 2031: U.S. Geological Survey Open- File Report 03-214, 8 chapters, 7 appendices. ---PAGE BREAK--- Revised GE 2135rpt 801 Bates Avenue, El Cerrito • 7770 Pardee Lane, Suite 101, Oakland, CA 94621 • Phone: [PHONE REDACTED] • Fax: [PHONE REDACTED] 41 Youd, T.L., and Hoose, S.N., 1978, Historic Ground Failures in Northern California Triggered by Earthquakes: U.S. Geological Survey Professional Paper 993, 177 5 pls. ---PAGE BREAK--- Revised GE 2135rpt 801 Bates Avenue, El Cerrito • 7770 Pardee Lane, Suite 101, Oakland, CA 94621 • Phone: [PHONE REDACTED] • Fax: [PHONE REDACTED] 42 6.0 AERIAL PHOTOGRAPHS Date Flight Line Frames Scale Type 08-02-39* BUT-BUU 189-95, 96 & 97 1:20,000 B & W Stereo 07-22-46* GC-CP 4-37 & 38 1:23,600 B & W Stereo 03-24-47** AV-11 02-07 & 08 1:20,000 B & W Stereo 09-16-49** AV-28 12-18 & 19 1:7,200 B & W Stereo 05-25-50* BUU 14G-38 & 39 1:20,000 B & W Stereo 05-03-57** AV-253 07-12 & 13 1:12,000 B & W Stereo 07-08-59** AV-337 10-17 & 18 1:9,600 B & W Stereo 05-07-73* CC 3526 1-90 & 91 1:12,000 B & W Stereo 10-01-80* GS-VEZR 1-29 & 30 1:20,000 B & W Stereo *Photographs available at the U.S. Geological Survey and at the California Geological Survey, both in Menlo Park, California at no charge **Photographs available at Pacific Aerial Surveys in Oakland, California for a fee ---PAGE BREAK--- FIGURES ---PAGE BREAK--- APPENDIX A Field Investigation ---PAGE BREAK--- A-1 APPENDIX A Field Investigation Our field exploration was performed August 11-14, 2008. Trenches and test pits were excavated using a rubber-tire-mounted Case 580 Super M backhoe equipped with a 2-ft-wide bucket. The bucket was fitted with rock teeth. Depths of excavations are as given in the logs. Test Pits were generally about 6 to 10 feet long; trenches were longer, as shown in the logs and in Figure 2. Widths were 2 feet where excavation depth was less than 5 feet: Test Pits TP-3 and TP-4. Where excavation depth exceeded 5 feet (Test Pits TP-1 and TP-2 and portions of Trenches T-1 and T-2), the upper few feet of the excavations were widened to about 6 to 8 feet for worker safety. Trenches and pits were backfilled loosely with the excavation spoils. Some settling and rutting of the contents should be expected. The soils are described in accordance with the Unified Soil Classification System (ASTM D- 2487.) The logs of the trenches and test pits and a key for classification of soil (Figure A-1) are included as part of this appendix. Rock strength classifications follow this scale: Friable Rock crushes under pressure between thumb and index finger. Weak Rock breaks under light hammer blow. Moderately strong Rock breaks under moderate hammer blow or multiple light hammer blows. Strong Rock breaks under heavy hammer blow or multiple moderate hammer blows. Very strong Rock difficult or impossible to break under multiple heavy hammer blows; makes ringing sound when struck. Representative soil samples were obtained from Trench T-1 and Test Pit TP-3 at selected depths appropriate to the investigation. A disturbed sample of soil was obtained from Trench T-1 by placing chunks of soil into a Ziploc plastic bag. Relatively undisturbed samples of soil from Test Pit TP-3 were obtained using a modified California sampler fitted with brass tubes. The sampler was driven into soil using the hydraulic force of the backhoe. All samples were sealed or capped to retain moisture and transported to our laboratory for evaluation and appropriate testing. ---PAGE BREAK--- A-2 Figure 2 shows locations of trenches and test pits. These locations were recorded in the field by hand tape-measuring from trees, fences, and walkways. These locations are accurate only to the extent implied by the locating methods used. The attached logs of trenches and test pits show our interpretations of the subsurface conditions in August 2008 and at the locations indicated, and it is not warranted that the logs are representative of subsurface conditions at other times or locations. ---PAGE BREAK--- A-3 Test Pit 1 0 – ½ ft topsoil. ½ – 1½ ft GRAVEL W. SAND (GC) — fill: yellowish brown, damp, dense, angular native basalt fragments. 1½ – 3½ ft Alternating GRAVEL (GC) and CLAY (CL) — fill: dark brown to yellowish brown, damp, dense/stiff, approx. four layers each ½ ft thick. 3½ – 4½ ft CLAY w. GRAVEL (CL) — colluvium: dark brown, damp, stiff, angular native basalt fragments. Test Pit 2 0 – ½ ft topsoil. ½ – 2½ ft Alternating GRAVEL (GC) and CLAY (CL) — fill: dark brown to yellowish brown, damp, dense/stiff, includes minor brick and concrete fragments, approx. three layers each 8 in. thick. 2½ – 3 ft CLAY w. GRAVEL (CL) — colluvium: dark brown, damp, stiff, angular native basalt fragments. 3 – 5 ft BASALT — spm: gray (fresh) to brown (weathered), strong, fracture spacing 1 to 6 in., maroon clay and iron-oxide coatings on fracture surfaces. Test Pit 3 0 – ½ ft topsoil. ½ – 3 ft CLAY w. GRAVEL (CL) — colluvium: dark brown, damp, stiff, angular native basalt fragments. Note: Test Pit 3 was excavated with the backhoe to a depth of only ½ ft. Soil logging below ½ was from samples retrieved using the mod. California sampler from ½ to 3 ft. Test Pit 4 0 – 1 ft CLAYEY GRAVEL (GC) — colluvium: dark brown, damp, angular native basalt fragments. 1 – 2½ ft BASALT — spm: gray (fresh) to brown (weathered), strong, ¼ ft to 1½ ft fracture spacing, maroon clay and iron-oxide coatings on fracture surfaces. No Free Groundwater was encountered in our test pits. ---PAGE BREAK--- APPENDIX B Laboratory Investigation ---PAGE BREAK--- B-1 APPENDIX B Laboratory Investigation The laboratory testing program was directed toward a quantitative and qualitative evaluation of the physical and mechanical properties of the soils underlying the site. The natural water content was determined on five samples of the materials recovered from the borings in accordance with ASTM Test Designation D-2216. These water contents are recorded on the boring logs at the appropriate sample depths. Dry density determinations were performed on one samples of the subsurface soils to evaluate their physical properties. The results of these tests are shown on the boring logs at the appropriate sample depths. Unconfined compression tests were performed on one undisturbed samples of the clayey subsurface soils to evaluate the undrained shear of these materials. The unconfined tests were performed in accordance with ASTM Test Designation D-2166 on samples having a diameter of 2.4 inches and a height-to-diameter ratio of at least two. Failure was taken as the peak normal stress. The results of these tests are presented on the boring logs at the appropriate sample depths. Atterberg Limit determinations were performed on one sample of the subsurface soils to determine the range of water content over which these materials exhibit plasticity. The Atterberg Limits were determined in accordance with ASTM Test Designations D-428 and D-424, latest editions. These values are used to classify the soil in accordance with the Unified Soil Classification System and to indicate the soil's compressibility and expansion potentials. ---PAGE BREAK--- APPENDIX C Guide Specifications - Site Earthwork ---PAGE BREAK--- C-1 APPENDIX C Guide Specifications - Site Earthwork 1.0 GENERAL 1.1 Scope of Work These specifications and applicable plans pertain to and include all site earthwork including, but not limited to, the finishing of all labor, tools, and equipment necessary for site clearing and stripping, disposal of excess materials, excavation, preparation of foundation materials for receiving fill, and placement and compaction of fill to the lines and grades shown on the project grading plans. 1.2 Performance The Contractor warrants all work to be performed and all materials to be furnished under this contract against defects in materials or workmanship for a period of year(s) from the date of written acceptance of the entire construction work by the Owner. Upon written notice of any defect in materials or workmanship during said year period, the Contractor shall, at the option of the Owner, repair or replace said defect and any damage to other work caused by or resulting from such defect without cost to the Owner. This shall not limit any rights of the Owner under the "acceptance and inspection" clause of this contract. The Contractor shall be responsible for the satisfactory completion of all site earthwork in accordance with the project plans and specifications. This work shall be observed and tested by a representative of GeoTrinity, hereinafter known as the Geotechnical Engineer. Both the Geotechnical Engineer and the Architect/Engineer are the Owner's representatives. If the Contractor should fail to meet the technical or design requirements embodied in this document and on the applicable plans, he shall make the necessary readjustments until all work is deemed satisfactory as determined by the Geotechnical Engineer and the Architect/Engineer. No deviation from the specifications shall be made except upon written approval of the Geotechnical Engineer or Architect/Engineer. No site earthwork shall be performed without the physical presence or approval of the Geotechnical Engineer. The Contractor shall notify the Geotechnical Engineer at least twenty- four hours prior to commencement of any aspect of the site earthwork. ---PAGE BREAK--- C-2 The Geotechnical Engineer shall be the Owner's representative to observe the grading operations during the site preparation work and the placement and compaction of fills. He shall make enough visits to the site to familiarize himself generally with the progress and quality of the work. He shall make a sufficient number of tests and/or observations to enable him to form an opinion regarding the adequacy of the site preparation, the acceptability of the fill material, and the extent to which the compaction of the fill, as placed, meets the specification requirements. Any fill that does not meet the specification requirements shall be removed and/or recompacted until the requirements are satisfied. In accordance with generally accepted construction practices, the Contractor shall be solely and completely responsible for working conditions at the job site, including safety of all persons and property during performance of the work. This requirement shall apply continuously and shall not be limited to normal work hours. Any construction review of the Contractor's performance conducted by the Geotechnical Engineer is not intended to include review of the adequacy of the Contractor's safety measures in, on or near the construction site. Upon completion of the construction work, the Contractor shall certify that all compacted fills and foundations are in place at the correct locations, have the correct dimensions, are plumb, and have been constructed in accordance with sound construction practice. In addition, he shall certify that the materials used are of the types, quantity and quality required by the plans and specifications. 1.3 Site and Foundation Conditions The Contractor is presumed to have visited the site and to have familiarized himself with existing site conditions and the soil report titled, "Revised Surface-Fault-Rupture Investigation and Geotechnical Investigation, 801 Bates Avnue, El Cerrito, California", dated June 24, 2009. The Contractor shall not be relieved of liability under the contract for any loss sustained as a result of any variance between conditions indicated by or deduced from the soil report and the actual conditions encountered during the course of the work. The Contractor shall, upon becoming aware of surface and/or subsurface conditions differing from those disclosed by the original soil investigation, notify the Owner as to the nature and extent of the differing conditions, first verbally to permit verification of the conditions, and then in writing. No claim by the Contractor for any conditions differing from those anticipated in the plans and specifications and disclosed by the soil investigation will be allowed unless the Contractor has so notified the Owner, verbally and in writing, as required above, of such changed conditions. ---PAGE BREAK--- C-3 1.4 Dust Control The Contractor shall assume responsibility for the alleviation or prevention of any dust nuisance on or about the site or off-site borrow areas. The Contractor shall assume all liability, including court costs of codefendant, for all claims related to dust or windblown materials attributable to his work. 2.0 DEFINITION OF TERMS Structural Fill: All soil or soil-rock material placed on-site in order to raise grades or to backfill excavations, and upon which the Geotechnical Engineer has conducted sufficient tests and/or observations to enable him to issue a written statement that, in his opinion, the fill has been placed and compacted in accordance with the specification requirements. On-Site Material: Material obtained from the required site excavations. Import Material: Material obtained from off-site borrow areas. ASTM Specifications: The American Society for Testing and Materials Standards, latest edition. Degree of Compaction: The ratio, expressed as a percentage, of the in-place dry density of the compacted fill material to the maximum dry density of the same material as determined by ASTM Test Designation D1557- 91. ---PAGE BREAK--- C-4 3.0 SITE PREPARATION 3.1 Clearing and Grubbing The contractor shall accept the site in its present condition and shall remove from the area of the designated project earthwork all obstructions including abandoned utilities, and any other matter determined by the Geotechnical Engineer to be deleterious. Such material shall become the property of the Contractor and shall be removed from the site. Holes resulting from the removal of underground obstructions that extend below finish grades shall be cleared and backfilled with structural fill. 3.2 Stripping Where vegetation exists, the site shall be stripped to a minimum depth of 3 inches or to such greater depth as the Geotechnical Engineer in the field may consider as being advisable to remove all surface vegetation and organic laden topsoil. Stripped topsoil with an organic content in excess of 3 percent by volume shall be stockpiled for possible use in landscaped areas. 4.0 EXCAVATION All excavations shall be performed to the lines and grades and within the tolerances specified on the project grading plans. All overexcavation below the grades specified shall be backfilled at the Contractor's expense and shall be compacted in accordance with the specifications. The Contractor shall assume full responsibility for the stability of all temporary construction slopes on-site. 5.0 SUBGRADE PREPARATION Surfaces to receive compacted fill, and those on which concrete slabs and pavements will be constructed, shall be scarified to a minimum depth of 6 inches and compacted. All ruts, hummocks, or other uneven surface features shall be removed by surface grading prior to placement of any fill materials. All areas which are to receive fill material shall be approved by the Geotechnical Engineer prior to placement of any fill material. ---PAGE BREAK--- C-5 6.0 GENERAL REQUIREMENTS FOR FILL MATERIAL All fill material must be approved by the Geotechnical Engineer. The material shall be a soil or soil-rock mixture which is free from organic matter or other deleterious substances. The fill material shall not contain rocks or rock fragments over 6 inches in greatest dimension and not more than 15 percent shall be over 2.5 inches in greatest dimension. On-site material having an organic content of less than 3 percent by volume is suitable for use as fill in all areas except where non-expansive import material is specified. All imported fill material shall be non-expansive with a plasticity index of 12 or less. 7.0 PLACING AND COMPACTING FILL MATERIAL All structural fill less than 5 feet thick shall be compacted by mechanical means to produce a minimum degree of compaction of 90 percent as determined by ASTM Test Designation DD1557-91. All structural fill greater than 5 feet in thickness shall be compacted to at least 95 percent relative compaction below the uppermost five feet. Field density tests shall be performed in accordance with either ASTM Test Designation D1556-82 (Sand-Cone Method) or ASTM Test Designation D2922-81 and D3017-88 (Nuclear Probe Method). The locations and number of field density tests shall be determined by the Geotechnical Engineer. The results of these tests and compliance with these specifications shall be the basis upon which satisfactory completion of work shall be judged by the Geotechnical Engineer. 8.0 TRENCH BACKFILL Pipeline trenches shall be backfilled with compacted structural fill placed in lifts not exceeding 8 inches of uncompacted thickness. If on-site soils are used, the material shall be compacted by mechanical means to a minimum degree of compaction of 90 percent. Imported sand may also be used for backfilling trenches provided it is compacted to at least 95 percent. If imported sand backfilling is used, sufficient water shall be added during the trench backfilling operations to prevent the soil from bulking during compaction. In all building pad and pavement areas, the upper 1 feet of trench backfill shall be compacted to a minimum degree of compaction of 95 percent. ---PAGE BREAK--- C-6 9.0 TREATMENT AFTER COMPLETION OF EARTHWORK After the earthwork operations have been completed and the Geotechnical Engineer has finished his observation of the work, no further earthwork operations shall be performed except with the approval of and under the observation of the Geotechnical Engineer. It shall be the responsibility of the Contractor to prevent erosion of freshly graded areas during construction and until such time as permanent drainage and erosion control measures have been installed. ---PAGE BREAK--- APPENDIX D Guide Specifications - Pavements ---PAGE BREAK--- D-1 APPENDIX D Guide Specifications - Asphalt Paving 1.0 GENERAL This portion of the work shall include all labor, materials, tools and equipment necessary for incidental to the completion of the pavement shown on the plans and as herein specified. 2.0 DEFINITION OF TERMS Pavement: Both asphalt concrete, and aggregate base materials. Subgrade: That portion of the construction on which asphalt concrete and aggregate base is to be placed. Standard Specifications: Standard Specifications of the State of California Department of Transportation, July 1992. ASTM Specifications: The 1993 edition of the American Society for Testing and Materials Standards. 3.0 MATERIALS 3.1 Asphalt Asphalt for prime coat shall be liquid asphalt, grade MC-70 conforming to the provisions of Sections 39 and 93 of the Standard Specifications. Asphalt for tack coat and seal coat shall be SS-1h asphalt emulsion conforming to Sections 37 and 94 of the Standard Specifications. Paving asphalt to be mixed with aggregate shall be steam refined asphalt conforming to the provisions of Section 92 of the Standard Specifications for viscosity grade AR 4000. 3.2 Mineral Aggregate for Asphalt Concrete: Type B Aggregate as specified in the Standard Specifications, Section 39, ½ inch maximum size, medium grading. ---PAGE BREAK--- D-2 4.0 CONSTRUCTION 4.1 Existing Pavement Remove the existing asphalt concrete and base to the subgrade elevation. Existing pavements which are removed can be used as fill material provided the asphalt is broken up to meet the maximum allowable size requirements for imported fill material. 4.2 Subgrade Preparation The Contractor shall prepare the surface of the various subgrades receiving subsequent pavement courses to the lines, grades and dimensions given on the plans. Isolated unstable areas shall be stabilized by recompaction or excavation and replacement of materials. The upper 6 inches of the subgrade soil shall be compacted to a density not less than 95 percent of that obtained in the laboratory according to Test Method ASTM D1557, latest edition. 4.3 Aggregate Base Aggregate base shall be spread and compacted in conformance with Standard Specifications Section 26 for Class 2 Aggregate Base. Finished aggregate base shall have the minimum depth shown and finished grade shall not vary more than 0.05 foot above or below the established grade. The aggregate base shall be compacted to a density not less than 95 percent of that obtained in the laboratory according to Test Method ASTM D1557, latest edition. 4.4 Prime Coat Apply prime coat at an approximate total rate of ¼ gallons per square yard to all areas receiving asphalt concrete. Conform to Section 39 of Standard Specifications. ---PAGE BREAK--- D-3 4.5 Tack Coat Apply a "tack coat" to all vertical faces, against which asphalt concrete is to be placed. Apply at a rate of from 0.02 gallon to 0.10 gallon per square yard. Conform to Section 39 of Standard Specifications. 4.6 Seal Coat Seal coat shall be diluted with an equal amount of water and applied at the rate of 0.10 gallon of the diluted emulsion per square yard of surface. The surface shall be free of dust and loose material prior to application. 4.7 Asphalt Concrete Asphalt concrete shall be spread and compacted on the prepared base in conformance with the lines, grades and dimensions shown on the drawing and as specified in Section 39 of the Standard Specifications. In addition to the compaction requirements described in Section 39 of the Standard Specifications, each layer of asphalt concrete (surface or base) shall be compacted to a density no less than 95 percent of that obtained in the laboratory according to ASTM Test Method D2041, latest edition. 4.8 Improper Workmanship Cracks, settling of surface, improper drainage and sloppy connection to previously laid surfaces will be construed as improper workmanship and will not be acceptable. ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- A P P E N D I X D 2 G E O T E C H N I C A L R E P O R T P E E R R E V I E W ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK---