Project Name: 475-493 St. John St. HRE Pleasanton
Historic Resources Evaluation - DRAFT
Project No: HP0932.2101.00
February 25, 2021
treanorhl.com 8
Figures 13 and 14. The accessory structures on the parcel.
5. ARCHITECTURAL STYLE
Lacking a clear architectural style the main building at 475 St. John Street is vernacular in nature. Constructed in the 1880s as a single-family house, the building currently does not illustrate a definite architectural style.
The main house at 493 St. John Street was identified as a late 19 th century vernacular form residential development by the City of Pleasanton. 2
Late nineteenth-century residential development in Pleasanton included several wood-frame, vernacular housing forms common in the period. Some of the examples display architectural ornament and detailing consistent with popular recognized styles, though most are architecturally modest.
Vernacular housing forms in Pleasanton from this period include three distinct types: small, single-story, ell- shaped dwellings, one or one-and-a-half-story side gable dwellings, and one or one-and-a-half-story end dwellings. The most numerous are the one-and-a-half-story, wood-frame, side gable dwellings, typically measuring a single room deep. These properties may have had modest classical or Greek Revival detailing such as cornice returns on gable ends, though most surviving examples retain little ornament. The dwellings typically had a symmetrical façade with a slightly off-center main entrance, and full-length, attached front porch.
3 The cottage at 493 St. John Street is a modest vernacular dwelling without a definite architectural style. The accessory structures on both parcels are utilitarian.
6. SITE HISTORY
In the 1860s, with the impending arrival of the railroad, large property owners in the vicinity of the Pleasanton town began subdividing property into lots and laying out streets. Owned by John Kottinger, the land bounded by Division Street on the south, the Arroyo del Valle on the north, and Main Street on the east was divided into a series of blocks and lots in 1868. This division includes the present-day St. John and St. Mary streets between Main and Division streets.
4 2 Email communication with City of Pleasanton, Community Development Department, December 11, 2020. 3 Architectural Resources Group, Inc., Pleasanton Downtown Historic Context Statement (March 2015), 85-86. 4 Pleasanton Downtown Historic Context Statement, 81.
Project Name: 475-493 St. John St. HRE Pleasanton
Historic Resources Evaluation - DRAFT
Project No: HP0932.2101.00
February 25, 2021
treanorhl.com 9
According to the Sanborn maps of the area, the subject block and its surroundings were largely developed by 1888: Main Street had a series of commercial buildings while the side streets were mostly residential. Garatti Winery established a large facility immediately to the northwest of the subject properties by 1939 and became one of the largest businesses in Pleasanton in the mid-20 th century.5 The winery complex was replaced by
housing in the early 1990s.6
475 St. John Street
T
he building first appears on the 1888 Sanborn map as a one-story wood frame dwelling. Irregular in plan, the dwelling had a partial-width front porch and an L-shaped rear porch. Two smaller sheds appeared to the northeast. Two additional accessory structures were constructed between 1898 and 1903, labeled as a hen coop and a chicken incubator on the 1903 Sanborn map. The dwelling received a small one-story addition to the west and had only one outbuilding in 1943. A one-story garage was constructed to the north by 1953, the outbuilding was demolished, the western addition was expanded, and the rear porch was enlarged and enclosed. It appears that the site layout and the building’s footprint had not changed until 1963. The main house received another porch addition in 1973, a kitchen addition in 1988, and a new front deck in 1989. The front deck was expanded once again in 1995.
7 According to the permits on file at the City of Pleasanton, the building received various additions and alterations over time. See below for the summary.
8 1973 A porch was added.
1977 The garage door was replaced with a glass door and grill. 1988 Reroofing, 640 sq. ft. kitchen addition, and interior remodel. 1989 A front deck and awnings were added to the southwest corner. The restaurant interior was expanded by covering this. A perimeter wrought iron fence and archway was constructed, and monumental sign was added.
1995 A 46’ by 24’ deck was added to the existing deck.
Figures 15 and 16. 475 St. John Street ca. 1988 (Museum on Main).
5 Sanborn maps; EDR, The EDR Aerial Photo Package, SCDC Saint John, 475 Saint John Street (August 31, 2020); The City of Pleasanton, Pleasanton General Plan 2005-2025 (adopted July 21, 2009), 12-8. 6 Historic Aerials by NETR Online.
7 Sanborn maps; The EDR Aerial Photo Package; City of Pleasanton Permit Center. 8 City of Pleasanton Permit Center.
Project Name: 475-493 St. John St. HRE Pleasanton
Historic Resources Evaluation - DRAFT
Project No: HP0932.2101.00
February 25, 2021
treanorhl.com 10
493 St. John Street
A
ccording to the material received from Museum on Main, the house at 493 St. John Street was designed and constructed in 1885 by Mr. Derendinger.” 9 A newspaper announcement from 1881 states that Joseph Derendinger’s residence was about to be finished. 10 The building first appears on the 1888 Sanborn map, so it was possibly constructed in the early 1880s.
The 1888 Sanborn map illustrates a one-and-a-half story L-shaped dwelling with a full-width front porch and a side porch facing east. Three one-story accessory structures to the north were attached to the main house, the southernmost one was a water mill with a tank on the roof. A one-story shed was at the northern end of the parcel. On the 1893 Sanborn map, the attached accessory structures were noted as a tank house and an outhouse; and the northern shed was replaced with two henhouses. The layout of the parcel and the buildings had not changed in 1903.
By 1929, a one-story dwelling was constructed immediately to the north of the main house: this one-story wood frame building was rectangular in plan and had a partial porch facing east. The outhouse and the water tank were removed from the main house, and the rear porch was expanded to be an L-shaped feature.
By 1943, the layout of the parcel and the main house was modified significantly. The main house received an addition at the northeast corner, so its footprint changed from an L to a rectangle. A bay window was added to the west façade. The full-width front porch remained the same. The rear dwelling was replaced by a larger L- shaped one with a south-facing front porch. A one-story garage (or a carport) and multiple free-standing outbuildings were constructed to the north and northeast of the houses. According to the later Sanborn maps and aerial photographs, the layout of the site remained unchanged until at least 1963.
The main house received multiple additions in the 1990s. The existing deck was expanded in 1995, and a small second-story deck with French doors was added to the front façade. 11 The entry was altered, and a new gable
roof projection was constructed at the front façade; new deck and railings were added ca. 2000. 12 The configuration of the west façade was significantly altered, and it appears that the front deck supports were replaced. Dormers were added on the east and west sides of the rear gable. None of the outbuildings are extant today, only the main house and the rear dwelling stands on site.
Figure 17. A photograph on 493 St. John Street from 1951 (Museum on Main).
9 Pleasanton Museum on Main. The name was spelled as “Derndinger” on the document. 10 Livermore Herald, October 13, 1881.
11 Building permits from City of Pleasanton.
12 Personal interview with the property owner, January 14, 2021.
Project Name: 475-493 St. John St. HRE Pleasanton
Historic Resources Evaluation - DRAFT
Project No: HP0932.2101.00
February 25, 2021
treanorhl.com 11
Figures 18 and 19. The house at 493 St. John Street in 1982 (Museum on Main).
Figure 20. 1888 Sanborn map, the subject parcels outlined by the dashed red line.
Project Name: 475-493 St. John St. HRE Pleasanton
Historic Resources Evaluation - DRAFT
Project No: HP0932.2101.00
February 25, 2021
treanorhl.com 12
Figure 21. 1893 Sanborn map, the subject parcels outlined by the dashed red line (Library of Congress).
Figure 22. 1898 Sanborn map, the subject parcels outlined by the dashed red line.
Project Name: 475-493 St. John St. HRE Pleasanton
Historic Resources Evaluation - DRAFT
Project No: HP0932.2101.00
February 25, 2021
treanorhl.com 13
Figure 23. 1903 Sanborn map, the subject parcels outlined by the dashed red line.
Figure 24. 1929 Sanborn map, the subject parcels outlined by the dashed red line (Museum on Main).
Project Name: 475-493 St. John St. HRE Pleasanton
Historic Resources Evaluation - DRAFT
Project No: HP0932.2101.00
February 25, 2021
treanorhl.com 14
Figure 25. 1943 Sanborn map, the subject parcels outlined by the dashed red line (Library of Congress).
Figure 26. 1953 Sanborn map, the subject parcels outlined by the dashed red line (The EDR Aerial Photo Package).
7. HISTORIC CONTEXT13
Located in eastern Alameda County, Pleasanton is bounded by the Diablo Range foothills on the north and south, the coastal Pleasanton Ridge on the west, and the adjacent Livermore Valley on the east. Major water c
ourses include the Arroyo del Valle and Arroyo de la Laguna. The earliest European presence in the vicinity of P
leasanton occurred in 1797. In the early 19 th century, the Mexican government granted most of the vicinity of Pleasanton, including the future town site, to members of the Bernal family; the area was inhabited primarily by cattle ranch workers, seasonal hunters, and trappers. With American annexation of California and the Gold Rush
13 Unless noted, largely summarized from Pleasanton Downtown Historic Context Statement, 9-13 and 83.
Project Name: 475-493 St. John St. HRE Pleasanton
Historic Resources Evaluation - DRAFT
Project No: HP0932.2101.00
February 25, 2021
treanorhl.com 15
in the late 1840s, the Bernal family established permanent homes on their rancho, both to capitalize on the proximity to travel routes and to protect their land claims. The initial settlers constructed adobe homes along the path of the Arroyo del Valle.
Originally called Alisal, the Pleasanton area remained sparsely populated in the 1850s, but news of the impending arrival of the railroad initiated an organized town development and an increase in population in the 1860s. The 1860s subdivisions along the axes of Main Street and the railroad formed the core of the Pleasanton town site.
The arrival of the Central Pacific Railroad sparked a commercial, agricultural, and residential boom in Pleasanton as the community gained greater access to the major regional urban markets of San Francisco and Oakland. Between the 1870s and World War II, Pleasanton became a major regional supplier of commodity crops like grain, livestock, and agricultural products like hay. Local farmers and later major corporate agricultural interests grew or raised grass crops, hops, feed and table grains, market fruits and vegetables, wine grapes, sugar beets, and dairy cows. Pleasanton became a major regional shipping center for grain and hay, as well as a local leader in viticulture. The community also became nationally and internationally known as a center of horse breeding and training by the late nineteenth century. In the early twentieth-century, Pleasanton was also a major regional dairy producer and commercial flower growing site.
Commercial activity in Pleasanton in the late nineteenth and early twentieth centuries clustered along Main Street and the Central Pacific Railroad line and centered on marketing and shipping agricultural commodities, servicing livestock, and providing retail, financial, legal, medical, and recreational services to residents. Industrial development in Pleasanton was limited, but included a major brickyard operation for Oakland’s Remillard Brick Company, gravel mining, and water supply infrastructure for the Spring Valley Water Company. Residential development on a substantive scale began in Pleasanton after the arrival of the Central Pacific Railroad in 1869, with development peaks in the 1880s and 1890s and the early decades of the twentieth century.
14 […]
Property types associated with post-railroad residential subdivision and development in Pleasanton [ca. 1869-1900] include residences exhibiting nationally popular forms and architectural detailing consistent with the Gothic Revival, Italianate, and Queen Anne styles as well as common nineteenth-century vernacular housing forms. Based on historic map evidence, residential buildings in the downtown neighborhoods of Pleasanton from the period consisted of largely single-story, rectangular or square plan dwellings with small rear dependencies. Toward the later decades of the nineteenth-century, more asymmetrical plan houses consistent with Queen Anne style housing forms appeared in greater numbers. Residential properties typically had one or more single-story, wood-frame outbuildings on the property to shelter horses, wheeled vehicles, poultry, and other uses. Few properties maintained tank houses after 1890. 15 Pleasanton incorporated as a city in 1894. In the early 20 th century, the community constructed a city hall and established a local high school. World War II brought a small boom in commercial and agricultural activity, spurred by the needs of the war effort and the nearby service members and war workers. The U.S. Navy constructed the Naval Construction Battalion Center in 1943 and later Camp Parks and Camp Shoemaker, just north of Pleasanton. After World War II, commercial and residential development in Pleasanton continued on the outskirts of the downtown area. The former agricultural districts saw development of large-scale research, office,
14 Pleasanton Downtown Historic Context Statement, 11-12. 15 Pleasanton Downtown Historic Context Statement, 83.
Project Name: 475-493 St. John St. HRE Pleasanton
Historic Resources Evaluation - DRAFT
Project No: HP0932.2101.00
February 25, 2021
treanorhl.com 16
and industrial complexes in the 1960s. The residential growth of Pleasanton continued until the 1970s; population doubled between 1950 and 1960, and more than quadrupled between 1960 and 1970.
8. ARCHITECT/BUILDER
The research did not reveal any architects or builders associated with the initial design of the building at 475 St.
John Street. According to information provided by Museum on Main, the house at 493 St. John Street was designed and constructed in 1885 by Mr. Derendinger.”
16 Joseph Derendinger was recorded as a wheel wright,
wood worker, and wagon maker in the 1880s records. 17
9. OWNERSHIP/OCCUPANCY HISTORY
According to Museum on Main, the main house at 493 St. John Street was constructed by Mr. Derendinger in 1885.18 Joseph Derendinger was born in France in 1842, and died in Pleasanton, Alameda in 1888. He was married to Magdalena Mohr in 1875. 19 His occupation was recorded as wheel wright, wood worker, and wagon maker in the 1880s records.20 A newspaper announcement from 1881 mentioned that Joseph Derendinger’s residence was about to be finished. 21 According to the 1916 U.S. Voter Registration records and the 1917-1918 World War I Draft Registration Cards, the Derendinger family continued to live on St. John Street in the early 20 th century.22
The property was later purchased by George Trimingham.
23 The Trimingham family lived at the 493 St. John
Street property from at least 1930 to 1965. The 1940 federal census lists painter Earl Trimingham and his family living at 34 St. John Street. The rear house at 36 St. John Street was also occupied by the members of the same family.
24 Earl Trimingham was the mayor and city councilman in Pleasanton from 1937 to 1950. A painting contractor and a World War I veteran, he also served on the Pleasanton Housing Authority board. His obituary in Oakland Tribune mentions his widow, Edith, living at the family home at 493 St. John Street in 1965. 25 A house tour brochure from Museum on Main notes that the Trimingham family owned the property in the 1980s.
The earlier occupancy of the 475 St. John property is unclear. According to the 1940s assessment map, the parcel was owned by Mary E. Steane and Lydia G. Steane. 26 Although the house number is not listed in the 1920
census, the Steane family lived on St. John Street. The 1930 and 1940 census records also logged the Steane family as occupants at the subject property.
27 The building at 475 St. John Street has been used as a restaurant since at least the mid-1970s.28
16 Pleasanton Museum on Main.
17 Voter registers and census data from Ancestry.com.
18 Museum on Main.
19 Sacramento Daily Union, October 11, 1875.
20 Voter registers and census data from Ancestry.com.
21 Livermore Herald, October 13, 1881.
22 Ancestry.com (accessed February 4, 2021).
23 Pleasanton Museum on Main.
24 Ancestry.com.
25 “Trimingham rites slated in Pleasanton,” Oakland Tribune, December 1, 1965. 26 Museum on Main.
27 Ancestry.com.
28 Museum on Main; newspaper ad from The Argus (Fremont, California), October 31, 1976; City of Pleasanton Permit Center.
Project Name: 475-493 St. John St. HRE Pleasanton
Historic Resources Evaluation - DRAFT
Project No: HP0932.2101.00
February 25, 2021
treanorhl.com 17
10. REGULATORY FRAMEWORK
The regulatory background provided below offers an overview of federal and state criteria used to assess historic significance.
National Register of Historic Places Criteria
National Register Bulletin Number 15, How to Apply the National Register Criteria for Evaluation , describes the Criteria for Evaluation as being composed of two factors. First, the property must be “associated with an important historic context.”
29 The National Register identifies four possible context types, of which at least one must be applicable at the national, state, or local level. As listed under Section 8, “Statement of Significance,” of the NRHP Registration Form, these are:
A. Property is associated with events that have made a significant contribution to the broad patterns of our history.
B. Property is associated with the lives of persons significant in our past.
C. Property embodies the distinctive characteristics of a type, period, or method of construction or represents the work of a master, or possesses high artistic values, or represents a significant and distinguishable entity whose components lack individual distinction.
D. Property has yielded, or is likely to yield, information important to prehistory or history. 30 Second, for a property to qualify under the National Register’s Criteria for Evaluation, it must also retain “historic integrity of those features necessary to convey its significance.” 31 While a property’s significance relates to its
role within a specific historic context, its integrity refers to “a property’s physical features and how they relate to its significance.”
32 To determine if a property retains the physical characteristics corresponding to its historic context, the National Register has identified seven aspects of integrity:
Location is the place where the historic property was constructed or the place where the historic event occurred...
Design is the combination of elements that create the form, plan, space, structure, and style of a property...
Setting is the physical environment of a historic property...
Materials are the physical elements that were combined or deposited during a particular period of time and in a particular pattern or configuration to form a historic property...
Workmanship is the physical evidence of the crafts of a particular culture or people during any given period in history or prehistory...
Feeling is a 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.
33 29 National Park Service, How to Apply the National Register Criteria for Evaluation, National Register Bulletin 15 (Washington, DC: United States Department of the Interior, 1997), 3.
30 National Park Service, How to Complete the National Register Registration Form, National Register Bulletin 16A (Washington, DC: United States Department of the Interior, 1997), 75.
31 National Park Service, National Register Bulletin 15, 3. 32 Ibid., 44.
33 Ibid., 44-45.
Project Name: 475-493 St. John St. HRE Pleasanton
Historic Resources Evaluation - DRAFT
Project No: HP0932.2101.00
February 25, 2021
treanorhl.com 18
Since integrity is based on a property’s significance within a specific historic context, an evaluation of a property’s integrity can only occur after historic significance has been established. 34
California Register of Historical Resources Criteria
The California Office of Historic Preservation’s Technical Assistance Series #6, California Register and National Register: A Comparison, outlines the differences between the federal and state processes. The criteria to be used when establishing the significance of a property for listing on the California Register of Historical Resources (CRHR) are very similar, with emphasis on local and state significance. They are:
1. It is 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; or
2. It is associated with the lives of persons important to local, California, or national history; or
3. It embodies the distinctive characteristics of a type, period, or method of construction or represents the work of a master, or possesses high artistic values; or
4. It has yielded, or is likely to yield, information important to prehistory or history of the local area, California, or the nation.
35 The CRHR requires the establishment of historic significance before integrity is considered. California’s integrity threshold is slightly lower than the federal level. As a result, some resources that are historically significant but do not meet National Register of Historic Places (NRHP) integrity standards may be eligible for listing on the CRHR.
36 California’s list of special considerations is shorter and more lenient than the NRHP. It includes some allowances for moved buildings, structures, or objects, as well as lower requirements for proving the significance of resources that are less than 50 years old and a more elaborate discussion of the eligibility of reconstructed buildings.
37 In addition to separate evaluations for eligibility for the CRHR, the state automatically lists on the CRHR resources that are listed or determined eligible for the NRHP through a complete evaluation process. 38 Integrity
Second, for a property to qualify under the CRHR’s Criteria for Evaluation, it must also retain “historic integrity of those features necessary to convey its significance.”
39 While a property’s significance relates to its role within a specific historic context, its integrity refers to “a property’s physical features and how they relate to its significance.”40 To determine if a property retains the physical characteristics corresponding to its historic
34 Ibid., 45.
35 California Office of Historic Preservation, California Register and National Register: A Comparison, Technical Assistance Series 6, (Sacramento, 2001), 1.
36 California Register and National Register: A Comparison. 37 California Register and National Register: A Comparison, 2. 38 All State Historical Landmarks from number 770 onward are also automatically listed on the California Register. California Office of Historic Preservation, California Register of Historical Resources: The Listing Process, Technical Assistance Series 5 (Sacramento, n.d.), 1. 39 United States Department of the Interior, How to Apply the National Register Criteria for Evaluation, National Register Bulletin, No. 15 (Washington, D.C., 1997), 3.
40 How to Apply the National Register Criteria for Evaluation, 44.
Project Name: 475-493 St. John St. HRE Pleasanton
Historic Resources Evaluation - DRAFT
Project No: HP0932.2101.00
February 25, 2021
treanorhl.com 19
context, the NRHP has identified seven aspects of integrity (identified above under the NRHP criteria), which the CRHR closely follows.41
Local Eligibility
Apart from the “7. Conservation and Open Space Element” of the Pleasanton General Plan 2005-2025, the City does not have any regulations regarding historic resources, or any other ordinance that identifies local historic resources. The plan sets goals to “designate, preserve, and protect the archaeological and historic resources within the Pleasanton Planning Area: and extablishes the policy to “preserve and rehabilitate those cultural and historic resources which are significant to Pleasanton because of their age, appearance, or history.” 42 The policy on the historical and archaeological resources does not include any local criteria for evaluation; rather the City uses those established for the CRHR to evaluate the significance of cultural resources. Therefore, the City relies on the CRHR criteria for determining eligibility of historic resources.
11. SIGNIFICANCE EVALUATION
Current Historic Status
The subject parcels have not previously been identified on any state or national historic resources inventory.
According to the Pleasanton General Plan 2005-2025, both parcels are located within the Downtown Commercial Center which was identified as a heritage neighborhood. The 493 St. John Street property was also identified as a historic structure in the Pleasanton General Plan 2005-2025.43 The most recent Downtown Specific Plan (adopted August 2019), Pleasanton Downtown Historic Context Statement (March 2015), or Pleasanton Limited Scope Historic Resource Survey (August 2015) do not identify the parcels at 475 and 493 St. John Street as historic.
475 St. John Street (APN 94-114-7)
Criterion A/1 – Association with significant events
The main building at 475 St. John Street was constructed pre-1888 during the post-railroad subdivision and development period in Pleasanton that took place from ca. 1869 to 1900. The area remained sparsely populated in the 1850s, but the arrival of the railroad increased the population as subdivisions along the axes of Main Street and the railroad formed the core of the Pleasanton town site in the 1860s. The arrival of the Central Pacific Railroad sparked a commercial, agricultural, and residential boom in Pleasanton. The subject property is associated with early residential development patterns in Pleasanton, specifically with the post-railroad subdivision and development period as one of the earlier residences in downtown. Therefore, the property appears eligible for listing on the NRHP or CRHR under Criterion A/1. The period of significance would be 1880s, when the main building was constructed.
Criterion B/2 – Persons
No persons of known historical significance appear to have been associated with the subject property. None of the owners or occupants have been identified as important to the history of Pleasanton or California. Therefore, the building does not appear eligible for listing on the NRHP or CRHR under Criterion B/2.
41 How to Apply the National Register Criteria for Evaluation, 1. 42 The City of Pleasanton, Pleasanton General Plan 2005-2025 (adopted July 21, 2009), pages 7-11 to 7-16, 7-35, 7-36. 43 The City of Pleasanton, Pleasanton General Plan 2005-2025 (adopted July 21, 2009), pages 7-13 to 7-16.
Project Name: 475-493 St. John St. HRE Pleasanton
Historic Resources Evaluation - DRAFT
Project No: HP0932.2101.00
February 25, 2021
treanorhl.com 20
Criterion C/3 – Architecture and Construction
The main building was originally constructed in the 1880s; however, it does not retain most of its original details or style having been greatly altered over time. It is of common construction and materials with no notable or special attributes, and the structure does not possess high artistic value. No architect, designer or builder has been identified. The main building does not embody the distinctive characteristics of a type or architectural style common during post-railroad residential development in Pleasanton. The utilitarian accessory structures are of common construction and materials with no notable or special attributes, and they do not possess high artistic value. Overall, the property does not appear eligible for listing on the NRHP or CRHR under Criterion C/3.
Criterion D/4 – Information Potential
Archival research provided no indication that the subject property has the potential to yield information important to the prehistory or history of the local area, California, or the nation. The subject property does not appear eligible for listing on the NRHP or CRHR under Criterion D/4.
Integrity
T
he property at 475 St. John Street retains integrity of location since it has not been moved. The property does not retain its integrity of association and feeling since it has not been used as a single-family house since at least the 1970s. The building has received multiple additions and alterations over time and its original form and massing is no longer evident. The building does not retain its scale and does not illustrate the original late 19 th
century vernacular architecture. The property does not retain sufficient integrity of design, materials, and workmanship. Finally, the integrity of setting has been significantly compromised by the construction of the adjacent hotel to the east and the residential development to the west. Overall, the property at 475 St. John Street does not retain sufficient integrity to communicate its significance under Criterion A/1 for its defined period of significance.
493 St. John Street (APN 94-114-8)
Criterion A/1 – Association with significant events
The main house at 493 St. John Street was constructed in the 1880s during the post-railroad subdivision and development period in Pleasanton that took place from ca. 1869 to 1900. The area remained sparsely populated in the 1850s, but the arrival of the railroad increased the population as subdivisions along the axes of Main Street and the railroad formed the core of the Pleasanton town site in the 1860s. The arrival of the Central Pacific Railroad sparked a commercial, agricultural, and residential boom in Pleasanton. The subject property is associated with early residential development patterns in Pleasanton, specifically with the post-railroad subdivision and development period as one of the earlier residences in downtown. Therefore, the property appears eligible for listing on the NRHP or CRHR under Criterion A/1. The period of significance would be 1880s, when the main house was constructed.
The cottage to the north was constructed between 1929 and 1943, replacing an earlier dwelling on site. Neither the cottage nor the more recent accessory structures are associated with significant events of development patterns.
Criterion B/2 – Persons
No persons of known historical significance appear to have been associated with the subject property. The Trimingham family lived at the 493 St. John Street property from at least 1930 to 1965. Earl Trimingham was the mayor and city councilman in Pleasanton from 1937 to 1950. Even though Trimingham was active in administration of Pleasanton during the early to mid-20 th century, research has not revealed any information
about Trimingham’s contributions being historically important in the city’s development. None of the other
Project Name: 475-493 St. John St. HRE Pleasanton
Historic Resources Evaluation - DRAFT
Project No: HP0932.2101.00
February 25, 2021
treanorhl.com 21
owners or occupants of the main house or the cottage have been identified as important to the history of Pleasanton or California. Therefore, the building does not appear eligible for listing on the NRHP or CRHR under Criterion B/2.
Criterion C/3 – Architecture and Construction
Constructed in the 1880s, the main house at 493 St. John Street is an example of a late 19 th century vernacular form residential development in Pleasanton. The main building embodies some characteristics of the style common during the post-railroad residential development in Pleasanton including its one-and-a-half-story, wood-frame, side gable massing with a front porch and modest classical detailing. The main house was possibly constructed by its earliest owner, Joseph Derendinger who is not considered a master architect or builder.
The cottage to the north is of common construction and materials with no notable or special attributes, and the structure does not possess high artistic value. No architect, designer or builder has been identified. It does not embody the distinctive characteristics of a type or common architectural style. The utilitarian accessory structures are of common construction and materials with no notable or special attributes, they do not possess high artistic value.
Overall, the main house at 493 St. John Street appears eligible for listing on the NRHP and CRHR under Criterion C/3 as an example of a late 19
th century vernacular form , post-railroad residential development in Pleasanton.
The period of significance would be 1880s when the property was constructed.
Criterion D/4 – Information Potential
Archival research provided no indication that the subject property has the potential to yield information important to the prehistory or history of the local area, California, or the nation. The subject property does not appear eligible for listing on the NRHP or CRHR under Criterion D/4.
Integrity
T
he property at 493 St. John Street retains integrity of location since it has not been moved. The property retains its integrity of association and feeling because it has been used for residential purposes since its construction.
The main house has received multiple additions and alterations over time. Even though the original massing and form is still discernable, the house no longer illustrates its late 19 th century vernacular architecture. The main
entrance was expanded, the window configuration was modified and a deck was added at the front façade, dormers were added to the east, and a horizontal addition expanded the building to the west. The building’s alterations and addition have significantly diminished integrity of design, materials, and workmanship. Integrity of setting has also been significantly compromised by construction of the adjacent hotel to the east and the residential development to the west. Overall, the property does not retain sufficient integrity to communicate its significance under Criteria A/1 and C/3 for its defined period of significance.
12. CONCLUSION
Based on the above evaluation, the subject property at 475 St. John Street in Pleasanton does not appear individually eligible for the NRHP or CRHR as it was not found to possess sufficient integrity under criterion A/1 for its period of significance. Additionally, the property at 493 St. John Street in Pleasanton does not appear individually eligible for the NRHP or CRHR as it was not found to possess sufficient integrity under criteria A/1 and C/3 for its period of significance.
Project Name: 475-493 St. John St. HRE Pleasanton
Historic Resources Evaluation - DRAFT
Project No: HP0932.2101.00
February 25, 2021
treanorhl.com 22
BIBLIOGRAPHY
Ancestry.com.
Architectural Resources Group, Inc. Pleasanton Downtown Historic Context Statement. March 2015.
California Office of Historic Preservation. California Register and National Register: A Comparison, Technical Assistance Series 6. Sacramento, CA: California Department of Parks and Recreation, 2001.
California Office of Historic Preservation. California Register of Historical Resources: The Listing Process .
Technical Assistance Series 5. Sacramento, CA: California Department of Parks and Recreation, n.d.
City of Pleasanton. Community Development Department.
---. Downtown Specific Plan. Adopted August 2019.
----. Permit Center.
----.
Pleasanton General Plan 2005-2025. Adopted July 21, 2009.
EDR. The EDR Aerial Photo Package, SCDC Saint John, 475 Saint John Street . August 31, 2020.
Google Earth.
Google Maps.
Historic Aerials by NETR Online. https://www.historicaerials.com/viewer.
Katherine Petrin Consulting and Architectural Resources Group, Inc. Pleasanton Limited Scope Historic Resources Survey. August 2015.
Livermore Herald.
National Park Service. How to Apply the National Register Criteria for Evaluation, National Register Bulletin 15.
Washington, DC: United States Department of the Interior, 1997.
National Park Service. How to Complete the National Register Registration Form, National Register Bulletin 16A.
Washington, DC: United States Department of the Interior, 1997.
Oakland Tribune.
Pleasanton Museum on Main.
Sacramento Daily Union.
Sanborn Fire Insurance Maps.
The Argus.
Project Name: 475-493 St. John St. HRE Pleasanton
Historic Resources Evaluation - DRAFT
Project No: HP0932.2101.00
February 25, 2021
treanorhl.com 23
APPENDIX
DPR FORMS
P1. Other Identifier:
DPR 523A (9/2013) *Required information
State of California The Resources Agency Primary #
DEPARTMENT OF PARKS AND RECREATION HRI #
PRIMARY RECORD Trinomial
NRHP Status Code
Other Listings
Review Code Reviewer Date
*P2. Location: Not for Publication U nrestricted *a. County Alameda and (P2c, P2e, and P2b or P2d. Attach a Location Map as necessary.) *b. USGS 7.5' Quad Date T ; R ; of of Sec ; B.M. c. Address 475 St. John Street City Pleasanton Zip 94566 d. UTM: (Give more than one for large and/or linear resources) Zone , mE/ mN e. Other Locational Data: (e.g., parcel #, directions to resource, elevation, decimal degrees, etc., as appropriate) APN 94-114-7
*P3a. Description: (Describe resource and its major elements. Include design, materials, condition, alterations, size, setting, and boundaries)
The subject property at 475 St. John Street is in downtown Pleasanton. Located on the southern side of the block roughly bounded by St. John Street to the south, Main Street to the east, Arroyo del Valle to the north, and the railroad tracks to the west, the subject parcel is close to the commercial center of Pleasanton which lies to the east and south.
Low-rise residential buildings, mostly single-family houses, appear to the west.
The main building on the site, the restaurant, is lo
cated nearest St. John Street and has had numerous additions over the years. The additions almost completely surround the original structure which can be identified by the truncated hip roof. Behind the restaurant structure is a large, paved patio area surrounded by several accessory structures. (See Continuation Sheet.)
*P3b. Resource Attributes: (List
attributes and codes)
*P4. Resources Present: Building
Structure Object Site District
Element of District Other
(Isolates, etc.)
P5b. Description of Photo : (view,
date, accession #)
The front (south) façade, TreanorHL,
January 2021.
*P6. Date Constructed/Age and
Source: Historic Prehistoric
Both
Pre-1888, Sanborn maps
*P7. Owner and Address:
*P8. Recorded by: (Name, affiliation,
and address)
TreanorHL
460 Bush Street San Francisco, CA
*P9. Date Recorded: Feb 25, 2021
*P10. Survey Type: (Describe)
Intensive survey
*P11. Report Citation : (Cite survey
report and other sources, or enter "none.") TreanorHL, 475-493 St. John Street Pleasanton, CA, Historic Resources Evaluation – Draft, February 25, 2021
*Attachments: NONE Location Map Continuation Sheet Building, Structure, and Object Record Archaeological Record District Record Linear Feature Record Milling Station Record Rock Art Record Artifact Record Photograph Record Other (List):
P5a. Photograph or Drawing (Photograph required for buildings, structures, and objects.)
*Resource Name or # (Assigned by recorder) 475 St. John Street *NRHP Status Code
DPR 523B (9/2013) *Required information
State of California The Resources Agency Primary #
DEPARTMENT OF PARKS AND RECREATION HRI#
BUILDING, STRUCTURE, AND OBJECT RECORD
(This space reserved for official comments.)
(Sketch Map with north arrow required.)
B1. Historic Name:
B2. Common Name: 475 St. John Street
B3. Original Use: Residential B4. Present Use: Commercial *B5. Architectural Style: Vernacular
*B6. Construction History: (Construction date, alterations, and date of alterations) Constructed pre-1888. (See Continuation Sheet.)
*B7. Moved? No Yes Unknown Date: Original Location:
*B8. Related Features:
B9a. Architect: b. Builder:
*B10. Significance: Theme Area
Period of Significance. Property Type Applicable Criteria (Discuss importance in terms of historical or architectural context as defined by theme, period, and geographic scope. Also address integrity.)
Located in eastern Alameda County, Pleasanton is bounded by the Diablo Range foothills on the north and south, the coastal Pleasanton Ridge on the west, and the adjacent Livermore Valley on the east. Major water courses include the A
rroyo del Valle and Arroyo de la Laguna. The earliest European presence in the vicinity of Pl easanton occurred in 1797. In the early 19th century, the Mexican government granted most of the vicinity of Pleasanton, including the future town site, to members of the Bernal family; the area was inhabited primarily by cattle ranch workers, seasonal hunters, and trappers. With American annexation of California and the Gold Rush in the late 1840s, the Bernal family established permanent homes on their rancho, both to capitalize on the proximity to travel routes and to protect their land claims. The initial settlers constructed adobe homes along the path of the Arroyo del Valle. (See Continuation Sheet.)
B11. Additional Resource Attributes: (List attributes and codes)
*B12. References:
See Continuation Sheets.
B13. Remarks:
*B14. Evaluator: TreanorHL
*Date of Evaluation: February 25, 2021
DPR 523L (Rev. 1/1995)(Word 9/2013)
State of California Natural Resources Agency Primary# DEPARTMENT OF PARKS AND RECREATION HRI #
Trinomial
CONTINUATION SHEET
Property Name: 475 St. John Street
*P3a. Description, Continued:
Constructed pre-1888 this one-story over partial basement, restaurant building is complex in plan. The wood-frame structure has horizontal wood siding with simple stucco panels present at the front and east side additions. A small portion of the front façade, around the entry door also features stucco cladding.
The complex roof structure includes a truncated hip section with gable end roofs projecting from the hip along with several flat and shed roof sections. Asphalt shingles clad the sloped roof sections while roll- asphalt roofing clads the flat sections. The primary window type is vinyl-sash, six-over-six, single-hung.
Canvas awnings shelter some of the windows near the front of the building. Concrete steps, flanked by ornate metal railings, lead up to the entry door. The multi-lite wood door is sheltered by a canvas awning.
A dining patio and ramp stand to the northwest of the restaurant. The ramp accesses an entry off the patio.
An interior brick chimney stack is visible at the east side of the structure. Notable features include the flat roof additions at the southwest corner of the building, the truncated hip roof of the original structure and the numerous other additions. Alterations to the restaurant include window replacements and numerous small additions off every façade. The overall condition of the restaurant is good.
The street facing (south) façade of the restaurant features a raised entry, accessed by concrete steps. The entry door and steps are located to the west side of the structure and are flanked by a single window to the west and a grouping of five windows to the east. A raised gable roof interrupts the flat roof of the enclosed porch addition and helps identifying the entrance. The restaurant’s name “Barone’s” is painted on the gable end. A canvas awning shelters the multi-lite wood door, while another canvas awning wraps the southeast corner of the building and protects the windows. A dining patio accessed by a wood ramp is west of the building. Currently the patio and ramp are covered by a series of awnings and tents. A flat roof addition is set back from the main façade and features similar windows. Below each window on the main façade is a simple stucco panel surrounded by flat wood trim.
The east façade features a grouping of three multi-lite vinyl-sash windows at the southernmost enclosed porch addition and a grouping of nine identical windows at the side addition. Below the windows at the southernmost enclosed porch addition are stucco clad panels surrounded by flat wood trim, while the grouping of nine windows has panels that feature horizontal wood siding that match the rest of the cladding on this façade. Wood lattice hides the foundation and raised floor framing of the addition on this side of the structure. North of the addition is a deck. A shed roof addition, constructed off the back of the original house, features two openings that are currently covered with metal panels. A hip roof addition toward the north end of the elevation has a single, multi-panel door at the patio level. A small, shed roof addition adorns the southern end of this addition. From the patio wooden stairs lead up to a single door which accesses the shed roof addition at the most northern end of the structure. Both additions are clad in horizontal wood siding and feature simple wood trim at openings.
The north façade features numerous additions. The east side addition has a pair of multi-lite wood doors opening onto a raised deck. The shed roof addition features a single opening that is currently covered. A smaller shed roof addition has no openings but features a giant “B” for Barone’s painted on the wood siding while the rear addition with a hip roof is centered on this façade. The shed roof addition off the hip roof section has no openings on this side.
The west façade of the building features a hip roof addition at the southern end. This addition has a multi- lite fixed vinyl-sash window. The roof of the addition is set below the roofline of the original structure.
DPR 523L (Rev. 1/1995)(Word 9/2013)
State of California Natural Resources Agency Primary# DEPARTMENT OF PARKS AND RECREATION HRI #
Trinomial
CONTINUATION SHEET
Property Name: 475 St. John Street
The northern side of the hip roof addition has a single-hung multi-lite vinyl-sash window. A flat roof addition, with a single door, is located at the southern end of the addition while a metal electrical enclosure is located at the northern end. The northwest corner of the original structure is visible. A single opening on the north façade of the original structure has been covered with a piece of wood. Off the rear gable end section of the building is an addition constructed of concrete masonry units. This addition is a single-story and is enclosed with wood lattice on the southern end, where a paneled door provides access to the space. Mechanical units are housed on the flat roof. Another flat roof addition is located near the north end of the building and features a mix of cladding materials – vertical siding, vinyl panels and wood lattice. The northern most shed roof addition is raised above the ground and accessed by wood stairs. A single door punctuates the horizontal cladding material.
Accessory Structures
Several accessory structures are located north of the restaurant. A single-story, gable roof building is located northwest of the restaurant. Four other single-story structures flank the paved patio and dining area. These structures are open on one side and serve as outdoor bars. All structures are clad in horizontal vinyl planks. All accessory buildings were added to the site over the last two decades and are in good condition.
The south and east façades.
Two of the accessory structures on the subject parcel.
DPR 523L (Rev. 1/1995)(Word 9/2013)
State of California Natural Resources Agency Primary# DEPARTMENT OF PARKS AND RECREATION HRI #
Trinomial
CONTINUATION SHEET
Property Name: 475 St. John Street
*B6. Construction History, Continued:
In the 1860s, with the impending arrival of the railroad, large property owners in the vicinity of the Pleasanton town began subdividing property into lots and laying out streets. Owned by John Kottinger, the land bounded by Division Street on the south, the Arroyo del Valle on the north, and Main Street on the east was divided into a series of blocks and lots in 1868. This division includes the present-day St.
John and St. Mary streets between Main and Division streets. 1 According to the Sanborn maps of the area, the subject block and its surroundings were largely developed by 1888: Main Street had a series of commercial buildings while the side streets were mostly residential.
Garatti Winery established a large facility to the northwest of the subject property by 1939 and became one of the largest businesses in Pleasanton in the mid-20 th century.2 The winery complex was replaced by
housing in the early 1990s.3
The main building at 475 St. John Street first appears on the 1888 Sanborn map as a one-story wood frame dwelling. Irregular in plan, the dwelling had a partial-width front porch and an L-shaped rear porch.
Two smaller sheds appeared to the northeast. Two additional accessory structures were constructed between 1898 and 1903, labeled as a hen coop and a chicken incubator on the 1903 Sanborn map. The dwelling received a small one-story addition to the west and had only one outbuilding in 1943. A one- story garage was constructed to the north by 1953, the outbuilding was demolished, the western addition was expanded, and the rear porch was enlarged and enclosed. It appears that the site layout and the building’s footprint had not changed until 1963. The main house received another porch addition in 1973, a kitchen addition in 1988, and a new front deck in 1989. The front deck was expanded once again in 1995.
4 According to the permits on file at the City of Pleasanton, the building received various additions and alterations over time. See below for the summary.
5 1973 A porch was added.
1977 The garage door was replaced with a glass door and grill. 1988 Reroofing, 640 sq. ft. kitchen addition, and interior remodel. 1989 A front deck and awnings were added to the southwest corner. The restaurant interior was expanded by covering this. A perimeter wrought iron fence and archway was constructed, and monumental sign was added.
1995 A 46’ by 24’ deck was added to the existing deck.
*B10. Significance, Continued:
Originally called Alisal, the Pleasanton area remained sparsely populated in the 1850s, but news of the impending arrival of the railroad initiated an organized town development and an increase in population in the 1860s. The 1860s subdivisions along the axes of Main Street and the railroad formed the core of the Pleasanton town site.
The arrival of the Central Pacific Railroad sparked a commercial, agricultural, and residential boom in Pleasanton as the community gained greater access to the major regional urban markets of San
DPR 523L (Rev. 1/1995)(Word 9/2013)
State of California Natural Resources Agency Primary# DEPARTMENT OF PARKS AND RECREATION HRI #
Trinomial
CONTINUATION SHEET
Property Name: 475 St. John Street
Francisco and Oakland. Between the 1870s and World War II, Pleasanton became a major regional supplier of commodity crops like grain, livestock, and agricultural products like hay. Local farmers and later major corporate agricultural interests grew or raised grass crops, hops, feed and table grains, market fruits and vegetables, wine grapes, sugar beets, and dairy cows. Pleasanton became a major regional shipping center for grain and hay, as well as a local leader in viticulture. The community also became nationally and internationally known as a center of horse breeding and training by the late nineteenth century. In the early twentieth-century, Pleasanton was also a major regional dairy producer and commercial flower growing site.
Commercial activity in Pleasanton in the late nineteenth and early twentieth centuries clustered along Main Street and the Central Pacific Railroad line and centered on marketing and shipping agricultural commodities, servicing livestock, and providing retail, financial, legal, medical, and recreational services to residents. Industrial development in Pleasanton was limited, but included a major brickyard operation for Oakland’s Remillard Brick Company, gravel mining, and water supply infrastructure for the Spring Valley Water Company. Residential development on a substantive scale began in Pleasanton after the arrival of the Central Pacific Railroad in 1869, with development peaks in the 1880s and 1890s and the early decades of the twentieth century. 6 […]
Property types associated with post-railroad residential subdivision and development in Pleasanton [ca. 1869-1900] include residences exhibiting nationally popular forms and architectural detailing consistent with the Gothic Revival, Italianate, and Queen Anne styles as well as common nineteenth- century vernacular housing forms. Based on historic map evidence, residential buildings in the downtown neighborhoods of Pleasanton from the period consisted of largely single-story, rectangular or square plan dwellings with small rear dependencies. Toward the later decades of the nineteenth- century, more asymmetrical plan houses consistent with Queen Anne style housing forms appeared in greater numbers. Residential properties typically had one or more single-story, wood-frame outbuildings on the property to shelter horses, wheeled vehicles, poultry, and other uses. Few properties maintained tank houses after 1890.
7 Pleasanton incorporated as a city in 1894. In the early 20th century, the community constructed a city hall and established a local high school. World War II brought a small boom in commercial and agricultural activity, spurred by the needs of the war effort and the nearby service members and war workers. The U.S. Navy constructed the Naval Construction Battalion Center in 1943 and later Camp Parks and Camp Shoemaker, just north of Pleasanton. After World War II, commercial and residential development in Pleasanton continued on the outskirts of the downtown area. The former agricultural districts saw development of large-scale research, office, and industrial complexes in the 1960s. The residential growth of Pleasanton continued until the 1970s; population doubled between 1950 and 1960, and more than quadrupled between 1960 and 1970.
Architect/Builder
The research did not reveal any architects or builders associated with the initial design of the building at 475 St. John Street.
Architectural Style
Lacking a clear architectural style, the main building at 475 St. John Street is vernacular in nature.
DPR 523L (Rev. 1/1995)(Word 9/2013)
State of California Natural Resources Agency Primary# DEPARTMENT OF PARKS AND RECREATION HRI #
Trinomial
CONTINUATION SHEET
Property Name: 475 St. John Street
Constructed in the 1880s as a single-family house, the building currently does not illustrate a definite architectural style. The accessory structures on the parcel are utilitarian.
Occupants
The earlier occupancy of the 475 St. John property is unclear. According to the 1940s assessment map, the parcel was owned by Mary E. Steane and Lydia G. Steane.8 Although the house number is not listed in the 1920 census, the Steane family lived on St. John Street. The 1930 and 1940 census records also logged the Steane family as occupants at the subject property. 9 The building at 475 St. John Street has
been used as a restaurant since at least the mid-1970s.10
Current Historic Status
The subject parcel has not previously been identified on any state or national historic resources inventory.
According to the Pleasanton General Plan 2005-2025, it is located within the Downtown Commercial Center which was identified as a “heritage neighborhood.” The most recent Downtown Specific Plan (adopted August 2019), Pleasanton Downtown Historic Context Statement (March 2015), or Pleasanton Limited Scope Historic Resource Survey (August 2015) do not identify the property as historic.
Significance Evaluation – National Register of Historic Places (NRHP) & California Register of Historical Resources (CRHR) Evaluation11
Criterion A/1 – Association with significant events
The main building at 475 St. John Street was constructed pre-1888 during the post-railroad subdivision and development period in Pleasanton that took place from ca. 1869 to 1900. The area remained sparsely populated in the 1850s, but the arrival of the railroad increased the population as subdivisions along the axes of Main Street and the railroad formed the core of the Pleasanton town site in the 1860s. The arrival of the Central Pacific Railroad sparked a commercial, agricultural, and residential boom in Pleasanton.
The subject property is associated with early residential development patterns in Pleasanton, specifically with the post-railroad subdivision and development period as one of the earlier residences in downtown.
Therefore, the property appears eligible for listing on the NRHP or CRHR under Criterion A/1. The period of significance would be 1880s, when the main building was constructed.
Criterion B/2 – Persons
No persons of known historical significance appear to have been associated with the subject property.
None of the owners or occupants have been identified as important to the history of Pleasanton or California. Therefore, the building does not appear eligible for listing on the NRHP or CRHR under Criterion B/2.
Criterion C/3 – Architecture and Construction
The main building was originally constructed in the 1880s; however, it does not retain most of its original details or style having been greatly altered over time. It is of common construction and materials with no notable or special attributes, and the structure does not possess high artistic value. No architect, designer or builder has been identified. The main building does not embody the distinctive characteristics of a type or architectural style common during post-railroad residential development in Pleasanton. The utilitarian accessory structures are of common construction and materials with no notable or special attributes, and they do not possess high artistic value. Overall, the property does not appear eligible for listing on the
DPR 523L (Rev. 1/1995)(Word 9/2013)
State of California Natural Resources Agency Primary# DEPARTMENT OF PARKS AND RECREATION HRI #
Trinomial
CONTINUATION SHEET
Property Name: 475 St. John Street
NRHP or CRHR under Criterion C/3.
Criterion D/4 – Information Potential
Archival research provided no indication that the subject property has the potential to yield information important to the prehistory or history of the local area, California, or the nation. The subject property does not appear eligible for listing on the NRHP or CRHR under Criterion D/4.
Integrity
The property at 475 St. John Street retains integrity of location since it has not been moved. The property does not retain its integrity of association and feeling since it has not been used as a single-family house since at least the 1970s. The building has received multiple additions and alterations over time and its original form and massing is no longer evident. The building does not retain its scale and does not illustrate the original late 19
th century vernacular architecture. The property does not retain sufficient integrity of design, materials, and workmanship. Finally, the integrity of setting has been significantly compromised by the construction of the adjacent hotel to the east and the residential development to the west. Overall, the property at 475 St. John Street does not retain sufficient integrity to communicate its significance under Criterion A/1 for its defined period of significance.
In conclusion, the subject property at 475 St. John Street in Pleasanton does not appear individually eligible for the NRHP or CRHR as it was not found to possess sufficient integrity under criterion A/1 for its period of significance.
*B12. References (Endnotes):
1 Architectural Resources Group, Inc., Pleasanton Downtown Historic Context Statement (March 2015), 81. 2 Sanborn maps; EDR, The EDR Aerial Photo Package, SCDC Saint John, 475 Saint John Street (August 31, 2020); The City of Pleasanton, Pleasanton General Plan 2005-2025 (adopted July 21, 2009), 12-8. 3 Historic Aerials by NETR Online.
4 Sanborn maps; The EDR Aerial Photo Package; City of Pleasanton Permit Center. 5 City of Pleasanton Permit Center.
6 Pleasanton Downtown Historic Context Statement, 11-12. 7 Pleasanton Downtown Historic Context Statement, 83.
8 Museum on Main.
9 Ancestry.com.
10 Museum on Main; newspaper ad from The Argus (Fremont, California), October 31, 1976; City of Pleasanton Permit Center.
11 National Park Service, National Register Bulletin: How to apply the National Register criteria for evaluation, 75, https://www.nps.gov/nr/publications/bulletins/nrb15/nrb15_2.htm (accessed April 26, 2017); California Office of Historic Preservation, California Register and National Register: A Comparison, Technical Assistance Series 6 (Sacramento, 2001), 1.
P1. Other Identifier:
DPR 523A (9/2013) *Required information
State of California The Resources Agency Primary #
DEPARTMENT OF PARKS AND RECREATION HRI #
PRIMARY RECORD Trinomial
NRHP Status Code
Other Listings
Review Code Reviewer Date
*P2. Location: Not for Publication U nrestricted *a. County Alameda and (P2c, P2e, and P2b or P2d. Attach a Location Map as necessary.) *b. USGS 7.5' Quad Date T ; R ; of of Sec ; B.M. c. Address 493 St. John Street City Pleasanton Zip 94566 d. UTM: (Give more than one for large and/or linear resources) Zone , mE/ mN e. Other Locational Data: (e.g., parcel #, directions to resource, elevation, decimal degrees, etc., as appropriate) APN 94-114-8
*P3a. Description: (Describe resource and its major elements. Include design, materials, condition, alterations, size, setting, and boundaries)
The subject property at 493 St. John Street is in downtown Pleasanton. Located on the southern side of the block roughly bounded by St. John Street to the south, Main Street to the east, Arroyo del Valle to the north, and the railroad tracks to the west, the subject parcel is close to the commercial center of Pleasanton which lies to the east and south.
Low-rise residential buildings, mostly single-family houses, appear to the west.
The large deep lot features a main house (nearest to
St. John Street), a cottage to the northwest of the house, and three accessory buildings in the rear yard. Behind the gated rear yard is a large, paved parking lot. This parking area serves the restaurant to the east. Constructed prior to 1888, this two-story, over partial basement house is irregular in plan.
The vernacular wood-frame structure has horizontal wood siding and a steeply pitched, asphalt shingle-clad, cross- gable roof with dormers featuring a shed and gable roofs. (See Continuation Sheet.)
*P3b. Resource Attributes: (List
attributes and codes)
*P4. Resources Present: Building
Structure Object Site District
Element of District Other
(Isolates, etc.)
P5b. Description of Photo : (view,
date, accession #)
The front (south) and east façades,
TreanorHL, January 2021.
*P6. Date Constructed/Age and
Source: Historic Prehistoric
Both
1880s, Sanborn maps
*P7. Owner and Address:
*P8. Recorded by: (Name, affiliation,
and address)
TreanorHL
460 Bush Street San Francisco, CA
*P9. Date Recorded: Feb 25, 2021
*P10. Survey Type: (Describe)
Intensive survey
*P11. Report Citation : (Cite survey
report and other sources, or enter "none.") TreanorHL, 475-493 St. John Street Pleasanton, CA, Historic Resources Evaluation – Draft, February 25, 2021
*Attachments: NONE Location Map Continuation Sheet Building, Structure, and Object Record Archaeological Record District Record Linear Feature Record Milling Station Record Rock Art Record Artifact Record Photograph Record Other (List):
P5a. Photograph or Drawing (Photograph required for buildings, structures, and objects.)
*Resource Name or # (Assigned by recorder) 493 St. John Street *NRHP Status Code
DPR 523B (9/2013) *Required information
State of California The Resources Agency Primary #
DEPARTMENT OF PARKS AND RECREATION HRI#
BUILDING, STRUCTURE, AND OBJECT RECORD
(This space reserved for official comments.)
(Sketch Map with north arrow required.)
B1. Historic Name:
B2. Common Name: 493 St. John Street
B3. Original Use: Residential B4. Present Use: Residential *B5. Architectural Style: Late 19th century vernacular form residential development *B6. Construction History: (Construction date, alterations, and date of alterations) Constructed in the 1880s. (See Continuation Sheet.)
*B7. Moved? No Yes Unknown Date: Original Location:
*B8. Related Features:
B9a. Architect: b. Builder: Joseph Derendinger
*B10. Significance: Theme Area
Period of Significance. Property Type Applicable Criteria (Discuss importance in terms of historical or architectural context as defined by theme, period, and geographic scope. Also address integrity.)
Located in eastern Alameda County, Pleasanton is bounded by the Diablo Range foothills on the north and south, the coastal Pleasanton Ridge on the west, and the adjacent Livermore Valley on the east. Major water courses include the A
rroyo del Valle and Arroyo de la Laguna. The earliest European presence in the vicinity of Pl easanton occurred in 1797. In the early 19th century, the Mexican government granted most of the vicinity of Pleasanton, including the future town site, to members of the Bernal family; the area was inhabited primarily by cattle ranch workers, seasonal hunters, and trappers. With American annexation of California and the Gold Rush in the late 1840s, the Bernal family established permanent homes on their rancho, both to capitalize on the proximity to travel routes and to protect their land claims. The initial settlers constructed adobe homes along the path of the Arroyo del Valle. (See Continuation Sheet.)
B11. Additional Resource Attributes: (List attributes and codes)
*B12. References:
See Continuation Sheets.
B13. Remarks:
*B14. Evaluator: TreanorHL
*Date of Evaluation: February 25, 2021
DPR 523L (Rev. 1/1995)(Word 9/2013)
State of California Natural Resources Agency Primary# DEPARTMENT OF PARKS AND RECREATION HRI #
Trinomial
CONTINUATION SHEET
Property Name: 493 St. John Street
*P3a. Description, Continued:
The primary window type is vinyl-sash, nine-over-nine, single-hung. Decorative shutters flank many of the windows. A full-width entry porch with columns adorns the front (south) façade with a connecting deck wrapping around to the west side of the structure. A modest gable roof projection supported by round columns shelters the main entrance which consists of a paneled wood door and sidelights. The wood railing with turned balusters at the porch is identical to the railing at the second-floor deck. Notable features include the front porch, the enclosed eaves, the cornice returns at the eaves, the two interior chimney stacks, and the wood railings. Alterations to the main house include window replacement, relocation of the main entrance door, siding replacement, the installation of new railings and columns at the front façade, and numerous additions. A detached one-story, wood-frame cottage stands northwest of the main house. Three other detached structures are located behind the main house as well. Located around a paved parking area these prefabricated structures serve as a gym space, storage, and a detached garage. The overall condition of the main house, cottage and accessory structures is good.
Main House
The entrance to the house is located to the west end of the street facing façade of the main house. The enclosed entrance takes up a small portion of the original porch and projects from the original façade of the house. East of the entry are three windows with wide trim and a decorative crosshead. Each window is flanked by shutters. Round columns support the overhang at the porch area. Centered on the second floor is a wide shed roof dormer. A paired multi-lite French door provides access to the deck. A single, multi- lite window stands to each side of the door.
Two sets of paired windows are visible on the east façade under the gable end at the first floor. North of these windows are three additional openings – two single-hung and one slider. Two gable end dormers punctuate the cross-gable roof at the north side of this façade. A single-hung window and a decorative metal railing give interest to each dormer. All single-hung windows and surrounds match the windows on the south façade.
The dominant feature of the north façade is the second floor balcony supported by round columns. The balcony shelters the rear entrance which is slightly off center on the first floor. A single French door accesses the balcony. The balcony railing matches the railings on the front of the building. A single-hung window is east of the rear entry door.
A bay window, multi-lite door and single-hung window adorn the first floor of the west side of the building. At the second floor a single gable end dormer has a pair of windows. Just north of the dormer is a wood clad interior chimney stack. A paired French door with a multi-lite transom is located at the south end of the first floor under the gable end. Located directly below the ridge of the gable end at the second floor is a single-hung window. An uncovered wood deck spans most of this elevation and is connected to the entry porch. Vertical wood siding clads the railing around the deck perimeter.
Cottage
Constructed prior to 1943, this one-story, vernacular cottage is L-shaped in plan. The wood-frame building has horizontal wood siding and an asphalt shingle-clad, gable roof with a cross-gable addition to the north. Another small gable roof addition is off the rear (north) side of the structure. The raised foundation is hidden behind vertical wood cladding. The primary window types are wood-sash, one-over-
DPR 523L (Rev. 1/1995)(Word 9/2013)
State of California Natural Resources Agency Primary# DEPARTMENT OF PARKS AND RECREATION HRI #
Trinomial
CONTINUATION SHEET
Property Name: 493 St. John Street
one, double-hung and fixed wood-sash. Shutters flank all windows. An almost full-width porch with square wood supports shelters the main entrance, which consists of a wood panel door. The entrance door is centered on the main (south) façade with a single window to each side. The east façade has three single windows and a set of paired windows, as well as a paneled door accessed by wood stairs and a ramp. The north façade has a window centered on the small rear gable end addition, while a pair of fixed windows and a flush door are present on the cross-gable portion of the building. Wood stairs access this door. A pair of fixed windows and two single-hung windows punctuate the west façade. Notable features include the entry porch, the wood brackets at the eaves, the exposed rafter tails, the decorative shutters, and the wide flat trim at windows. Alterations to the cottage are minimal and limited to additions off the rear (north) side of the structure.
Left, the front (south) façade of the cottage; right, the east façade of the cottage.
Accessory Structures
Three small, prefabricated structures are in the north east corner of the yard around a paved parking area.
These accessory buildings were added to the site over the last five years. The single-story structures have metal-clad hipped and flat roofs as well as vinyl horizontal siding. The western most building has a single door on the west façade, the centrally located structure has a garage door on the southern façade, while the eastern most unit has a mix of window and door openings on three sides. All accessory buildings are in good condition.
The accessory structures on the parcel.
DPR 523L (Rev. 1/1995)(Word 9/2013)
State of California Natural Resources Agency Primary# DEPARTMENT OF PARKS AND RECREATION HRI #
Trinomial
CONTINUATION SHEET
Property Name: 493 St. John Street
*B6. Construction History, Continued:
In the 1860s, with the impending arrival of the railroad, large property owners in the vicinity of the Pleasanton town began subdividing property into lots and laying out streets. Owned by John Kottinger, the land bounded by Division Street on the south, the Arroyo del Valle on the north, and Main Street on the east was divided into a series of blocks and lots in 1868. This division includes the present-day St.
John and St. Mary streets between Main and Division streets. 1 According to the Sanborn maps of the area, the subject block and its surroundings were largely developed by 1888: Main Street had a series of commercial buildings while the side streets were mostly residential.
Garatti Winery established a large facility to the northwest of the subject property by 1939 and became one of the largest businesses in Pleasanton in the mid-20 th century.2 The winery complex was replaced by
housing in the early 1990s.3
According to the material received from Museum on Main, the house at 493 St. John Street was designed and constructed in 1885 by Mr. Derendinger.”4 A newspaper announcement from 1881 states that Joseph Derendinger’s residence was about to be finished.5 The building first appears on the 1888 Sanborn map, so it was possibly constructed in the early 1880s.
The 1888 Sanborn map illustrates a one-and-a-half story L-shaped dwelling with a full-width front porch and a side porch facing east. Three one-story accessory structures to the north were attached to the main house, the southernmost one was a water mill with a tank on the roof. A one-story shed was at the northern end of the parcel. On the 1893 Sanborn map, the attached accessory structures were noted as a tank house and an outhouse; and the northern shed was replaced with two henhouses. The layout of the parcel and the buildings had not changed in 1903.
By 1929, a one-story dwelling was constructed immediately to the north of the main house: this one-story wood frame building was rectangular in plan and had a partial porch facing east. The outhouse and the water tank were removed from the main house, and the rear porch was expanded to be an L-shaped feature.
By 1943, the layout of the parcel and the main house was modified significantly. The main house received an addition at the northeast corner, so its footprint changed from an L to a rectangle. A bay window was added to the west façade. The full-width front porch remained the same. The rear dwelling was replaced by a larger L-shaped one with a south-facing front porch. A one-story garage (or a carport) and multiple free-standing outbuildings were constructed to the north and northeast of the houses.
According to the later Sanborn maps and aerial photographs, the layout of the site remained unchanged until at least 1963.
The main house received multiple additions in the 1990s. The existing deck was expanded in 1995, and a small second-story deck with French doors was added to the front façade. 6 The entry was altered, and a
new gable roof projection was constructed at the front façade; new deck and railings were added ca. 2000.
7 The configuration of the west façade was significantly altered, and it appears that the front deck supports were replaced. Dormers were added on the east and west sides of the rear gable. None of the outbuildings are extant today, only the main house and the rear dwelling stands on site.
DPR 523L (Rev. 1/1995)(Word 9/2013)
State of California Natural Resources Agency Primary# DEPARTMENT OF PARKS AND RECREATION HRI #
Trinomial
CONTINUATION SHEET
Property Name: 493 St. John Street
A photograph on 493 St. John Street from 1951 (Museum on Main).
The house at 493 St. John Street in 1982 (Museum on Main).
*B10. Significance, Continued:
Originally called Alisal, the Pleasanton area remained sparsely populated in the 1850s, but news of the impending arrival of the railroad initiated an organized town development and an increase in population in the 1860s. The 1860s subdivisions along the axes of Main Street and the railroad formed the core of the Pleasanton town site.
The arrival of the Central Pacific Railroad sparked a commercial, agricultural, and residential boom in Pleasanton as the community gained greater access to the major regional urban markets of San Francisco and Oakland. Between the 1870s and World War II, Pleasanton became a major regional supplier of commodity crops like grain, livestock, and agricultural products like hay. Local farmers and later major corporate agricultural interests grew or raised grass crops, hops, feed and table grains, market fruits and vegetables, wine grapes, sugar beets, and dairy cows. Pleasanton became a major regional shipping center for grain and hay, as well as a local leader in viticulture. The community also became nationally and internationally known as a center of horse breeding and training by the late
DPR 523L (Rev. 1/1995)(Word 9/2013)
State of California Natural Resources Agency Primary# DEPARTMENT OF PARKS AND RECREATION HRI #
Trinomial
CONTINUATION SHEET
Property Name: 493 St. John Street
nineteenth century. In the early twentieth-century, Pleasanton was also a major regional dairy producer and commercial flower growing site.
Commercial activity in Pleasanton in the late nineteenth and early twentieth centuries clustered along Main Street and the Central Pacific Railroad line and centered on marketing and shipping agricultural commodities, servicing livestock, and providing retail, financial, legal, medical, and recreational services to residents. Industrial development in Pleasanton was limited, but included a major brickyard operation for Oakland’s Remillard Brick Company, gravel mining, and water supply infrastructure for the Spring Valley Water Company. Residential development on a substantive scale began in Pleasanton after the arrival of the Central Pacific Railroad in 1869, with development peaks in the 1880s and 1890s and the early decades of the twentieth century.8 […]
Property types associated with post-railroad residential subdivision and development in Pleasanton [ca. 1869-1900] include residences exhibiting nationally popular forms and architectural detailing consistent with the Gothic Revival, Italianate, and Queen Anne styles as well as common nineteenth- century vernacular housing forms. Based on historic map evidence, residential buildings in the downtown neighborhoods of Pleasanton from the period consisted of largely single-story, rectangular or square plan dwellings with small rear dependencies. Toward the later decades of the nineteenth- century, more asymmetrical plan houses consistent with Queen Anne style housing forms appeared in greater numbers. Residential properties typically had one or more single-story, wood-frame outbuildings on the property to shelter horses, wheeled vehicles, poultry, and other uses. Few properties maintained tank houses after 1890.
9 Pleasanton incorporated as a city in 1894. In the early 20th century, the community constructed a city hall and established a local high school. World War II brought a small boom in commercial and agricultural activity, spurred by the needs of the war effort and the nearby service members and war workers. The U.S. Navy constructed the Naval Construction Battalion Center in 1943 and later Camp Parks and Camp Shoemaker, just north of Pleasanton. After World War II, commercial and residential development in Pleasanton continued on the outskirts of the downtown area. The former agricultural districts saw development of large-scale research, office, and industrial complexes in the 1960s. The residential growth of Pleasanton continued until the 1970s; population doubled between 1950 and 1960, and more than quadrupled between 1960 and 1970.
Architect/Builder
According to information provided by Museum on Main, the house at 493 St. John Street was designed and constructed in 1885 by Mr. Derendinger.”10 Joseph Derendinger was recorded as a wheel wright, wood worker, and wagon maker in the 1880s records.11
Architectural Style
The main house at 493 St. John Street was identified as a late 19th century vernacular form residential development by the City of Pleasanton.12
Late nineteenth-century residential development in Pleasanton included several wood-frame, vernacular housing forms common in the period. Some of the examples display architectural ornament and detailing consistent with popular recognized styles, though most are architecturally modest.
DPR 523L (Rev. 1/1995)(Word 9/2013)
State of California Natural Resources Agency Primary# DEPARTMENT OF PARKS AND RECREATION HRI #
Trinomial
CONTINUATION SHEET
Property Name: 493 St. John Street
Vernacular housing forms in Pleasanton from this period include three distinct types: small, single- story, ell-shaped dwellings, one or one-and-a-half-story side gable dwellings, and one or one-and-a- half-story end dwellings. The most numerous are the one-and-a-half-story, wood-frame, side gable dwellings, typically measuring a single room deep. These properties may have had modest classical or Greek Revival detailing such as cornice returns on gable ends, though most surviving examples retain little ornament. The dwellings typically had a symmetrical façade with a slightly off-center main entrance, and full-length, attached front porch.
13 The cottage at 493 St. John Street is a modest vernacular dwelling without a definite architectural style.
The accessory structures on the parcel are utilitarian.
Occupants
According to Museum on Main, the main house at 493 St. John Street was constructed by Mr.
Derendinger in 1885.14 Joseph Derendinger was born in France in 1842, and died in Pleasanton, Alameda in 1888. He was married to Magdalena Mohr in 1875.15 His occupation was recorded as wheel wright, wood worker, and wagon maker in the 1880s records.16 A newspaper announcement from 1881 mentioned that Joseph Derendinger’s residence was about to be finished.17 According to the 1916 U.S.
Voter Registration records and the 1917-1918 World War I Draft Registration Cards, the Derendinger family continued to live on St. John Street in the early 20 th century.18
The property was later purchased by George Trimingham.
19 The Trimingham family lived at the 493 St.
John Street property from at least 1930 to 1965. The 1940 federal census lists painter Earl Trimingham and his family living at 34 St. John Street. The rear house at 36 St. John Street was also occupied by the members of the same family.
20 Earl Trimingham was the mayor and city councilman in Pleasanton from 1937 to 1950. A painting contractor and a World War I veteran, he also served on the Pleasanton Housing Authority board. His obituary in Oakland Tribune mentions his widow, Edith, living at the family home at 493 St. John Street in 1965.
21 A house tour brochure from Museum on Main notes that the Trimingham family owned the property in the 1980s.
Current Historic Status
The subject parcel has not previously been identified on any state or national historic resources inventory.
According to the Pleasanton General Plan 2005-2025, it is located within the Downtown Commercial Center which was identified as a “heritage neighborhood.” The property was also identified as a historic structure in the Pleasanton General Plan 2005-2025.22 The most recent Downtown Specific Plan (adopted August 2019), Pleasanton Downtown Historic Context Statement (March 2015), or Pleasanton Limited Scope Historic Resource Survey (August 2015) do not identify the parcel as historic.
Significance Evaluation – National Register of Historic Places (NRHP) & California Register of Historical Resources (CRHR) Evaluation23
Criterion A/1 – Association with significant events
The main house at 493 St. John Street was constructed in the 1880s during the post-railroad subdivision and development period in Pleasanton that took place from ca. 1869 to 1900. The area remained sparsely populated in the 1850s, but the arrival of the railroad increased the population as subdivisions along the axes of Main Street and the railroad formed the core of the Pleasanton town site in the 1860s. The arrival
DPR 523L (Rev. 1/1995)(Word 9/2013)
State of California Natural Resources Agency Primary# DEPARTMENT OF PARKS AND RECREATION HRI #
Trinomial
CONTINUATION SHEET
Property Name: 493 St. John Street
of the Central Pacific Railroad sparked a commercial, agricultural, and residential boom in Pleasanton.
The subject property is associated with early residential development patterns in Pleasanton, specifically with the post-railroad subdivision and development period as one of the earlier residences in downtown.
Therefore, the property appears eligible for listing on the NRHP or CRHR under Criterion A/1. The period of significance would be 1880s, when the main house was constructed.
The cottage to the north was constructed between 1929 and 1943, replacing an earlier dwelling on site.
Neither the cottage nor the more recent accessory structures are associated with significant events of development patterns.
Criterion B/2 – Persons
No persons of known historical significance appear to have been associated with the subject property. The Trimingham family lived at the 493 St. John Street property from at least 1930 to 1965. Earl Trimingham was the mayor and city councilman in Pleasanton from 1937 to 1950. Even though Trimingham was active in administration of Pleasanton during the early to mid-20 th century, research has not revealed any
information about Trimingham’s contributions being historically important in the city’s development.
None of the other owners or occupants of the main house or the cottage have been identified as important to the history of Pleasanton or California. Therefore, the building does not appear eligible for listing on the NRHP or CRHR under Criterion B/2.
Criterion C/3 – Architecture and Construction
Constructed in the 1880s, the main house at 493 St. John Street is an example of a late 19 th century
vernacular form residential development in Pleasanton. The main building embodies some characteristics of the style common during the post-railroad residential development in Pleasanton including its one-and- a-half-story, wood-frame, side gable massing with a front porch and modest classical detailing. The main house was possibly constructed by its earliest owner, Joseph Derendinger who is not considered a master architect or builder.
The cottage to the north is of common construction and materials with no notable or special attributes, and the structure does not possess high artistic value. No architect, designer or builder has been identified.
It does not embody the distinctive characteristics of a type or common architectural style. The utilitarian accessory structures are of common construction and materials with no notable or special attributes, they do not possess high artistic value.
Overall, the main house at 493 St. John Street appears eligible for listing on the NRHP and CRHR under Criterion C/3 as an example of a late 19th century vernacular form, post-railroad residential development in Pleasanton. The period of significance would be 1880s when the property was constructed.
Criterion D/4 – Information Potential
Archival research provided no indication that the subject property has the potential to yield information important to the prehistory or history of the local area, California, or the nation. The subject property does not appear eligible for listing on the NRHP or CRHR under Criterion D/4.
Integrity
The property at 493 St. John Street retains integrity of location since it has not been moved. The property
DPR 523L (Rev. 1/1995)(Word 9/2013)
State of California Natural Resources Agency Primary# DEPARTMENT OF PARKS AND RECREATION HRI #
Trinomial
CONTINUATION SHEET
Property Name: 493 St. John Street
retains its integrity of association and feeling because it has been used for residential purposes since its construction. The main house has received multiple additions and alterations over time. Even though the original massing and form is still discernable, the house no longer illustrates its late 19th century vernacular architecture. The main entrance was expanded, the window configuration was modified, and a deck was added at the front façade, dormers were added to the east, and a horizontal addition expanded the building to the west. The building’s alterations and addition have significantly diminished integrity of design, materials, and workmanship. Integrity of setting has also been significantly compromised by nearby residential and commercial development. Overall, the property does not retain sufficient integrity to communicate its significance under Criteria A/1 and C/3 for its defined period of significance.
In conclusion, the subject property at 493 St. John Street in Pleasanton does not appear individually eligible for the NRHP or CRHR as it was not found to possess sufficient integrity under criteria A/1 and C/3 for its period of significance.
*B12. References (Endnotes):
1 Architectural Resources Group, Inc., Pleasanton Downtown Historic Context Statement (March 2015), 81. 2 Sanborn maps; EDR, The EDR Aerial Photo Package, SCDC Saint John, 475 Saint John Street (August 31, 2020); The City of Pleasanton, Pleasanton General Plan 2005-2025 (adopted July 21, 2009), 12-8. 3 Historic Aerials by NETR Online.
4 Pleasanton Museum on Main. The name was spelled as “Derndinger” on the document. 5 Livermore Herald, October 13, 1881.
6 Building permits from City of Pleasanton.
7 Personal interview with the property owner, January 14, 2021. 8 Pleasanton Downtown Historic Context Statement, 11-12. 9 Pleasanton Downtown Historic Context Statement, 83.
10 Pleasanton Museum on Main.
11 Voter registers and census data from Ancestry.com.
12 Email communication with City of Pleasanton, Community Development Department, December 11, 2020. 13 Pleasanton Downtown Historic Context Statement, 85-86. 14 Museum on Main.
15 Sacramento Daily Union, October 11, 1875.
16 Voter registers and census data from Ancestry.com.
17 Livermore Herald, October 13, 1881.
18 Ancestry.com (accessed February 4, 2021).
19 Pleasanton Museum on Main.
20 Ancestry.com.
21 “Trimingham rites slated in Pleasanton,” Oakland Tribune, December 1, 1965.
DPR 523L (Rev. 1/1995)(Word 9/2013)
State of California Natural Resources Agency Primary# DEPARTMENT OF PARKS AND RECREATION HRI #
Trinomial
CONTINUATION SHEET
Property Name: 493 St. John Street
22 The City of Pleasanton, Pleasanton General Plan 2005-2025 (adopted July 21, 2009), pages 7-13 to 7-16. 23 National Park Service, National Register Bulletin: How to apply the National Register criteria for evaluation, 75, https://www.nps.gov/nr/publications/bulletins/nrb15/nrb15_2.htm (accessed April 26, 2017); California Office of Historic Preservation, California Register and National Register: A Comparison, Technical Assistance Series 6 (Sacramento, 2001), 1.
Appendix C
Archaeological Resources Assessment
The Archaeological Resources Assessment contains sensitive information pertaining to the location of archaeological resources and is confidential. The Archaeological Resources Assessment shall be kept on file with the City of Pleasanton Community Development Department.
Appendix D
Geotechnical Investigation
GEOTECHNICAL
STUDY
PROPOSED
RESIDENTIAL DEVELOPMENT
475 & 493 ST. JOHN STREET
PLEASANTON
, CALIFORNIA
JUNE
2 ,
20 2
2 PROJECT
PA
20 .10
55 .00
SUBMITTED TO:
Robson
Homes
2185 The Alameda, Suite 150
San Jose, CA 95126
PREPARED BY:
Geo
-
Logic Associates
dba Pacific Geotechnical Engineering
6300 San Ignacio Avenue,
Suite
A
San Jose
,
California
95119
(
408
)
778
-
2818
GEOTECHNICAL
STUDY
PROPOSED
RESIDENTIAL DEVELOPM
ENT
475
&
49 3
ST. JOHN STREET
PLEASANTON
, CALIFORNIA
Table of Contents
1 INTRODUCTION
................................
................................
................................
...............
1 1.1
PROJECT DESCRIPTION
................................
................................
................................
........
1 1.2
INFORMATION PROVIDED
................................
................................
................................
..
2 1.3
PURPOSE AND SCOPE OF
SERVICES
................................
................................
....................
2 2
SITE INVESTIGATION
................................
................................
................................
........
4 2.1
SUBSURFACE EXPLORATI
ON
................................
................................
...............................
4 2.1.1
Exploratory Drill Holes
................................
................................
............................
4 2.1.2
Cone Penetration Test Probes
................................
................................
................
4 2.2
LABORATORY TESTING
................................
................................
................................
........
5 3
FINDINGS
................................
................................
................................
.........................
6 3.1
SURFACE CONDITIONS
................................
................................
................................
........
6 3.2
SUBSURFACE CONDITION
S
................................
................................
................................
.
6 3.3
GROUNDWATER
................................
................................
................................
..................
7 3.4
VARIATIONS IN SUBSUR
FACE CONDITIONS
................................
................................
........
7 4
SEISMIC CONSIDERATIO
NS
................................
................................
...............................
8 4.1
EARTHQUAKE FAULTING
................................
................................
................................
.....
8 4.2
GROUND ACCELERATIONS
................................
................................
................................
..
8 4.3
SEISMICITY
................................
................................
................................
..........................
9 4.4
LIQUEFACTION
................................
................................
................................
....................
9 4.5
LATERAL SPREADING AN
D CREEK BANK STABILI
TY
................................
..........................
10 4.6
SEISMIC DESIGN PARAM
ETERS
................................
................................
.........................
12 5
DISCUSSION AND CONCL
USIONS
................................
................................
....................
13 5.1
GROUND RUPTURE
................................
................................
................................
...........
13 5.2
SEISMIC SHA
KING
................................
................................
................................
..............
13 5.3
LIQUEFACTION
................................
................................
................................
..................
13 5.4
SLOPE STABILITY AND
LATERAL DEFORMATIONS
................................
.............................
13 5.5
CREEK BANK EROSION
................................
................................
................................
......
14 5.6
EXPANSION POTENTIAL
OF SURFICIAL SOILS
................................
................................
....
14 5.7
EXISTING IMPROVEMENT
S
................................
................................
...............................
14 6
GEOTECHNICAL RECOMME
NDATIONS
................................
................................
............
16 6.1
BUILDING SET
-
BACK
................................
................................
................................
..........
16 6.2
EARTHWORK
................................
................................
................................
.....................
16 6.2.1
Site Preparation,
Clearing and Stripping
................................
...............................
16 6.2.2
Excavation, Temporary Construction Slopes, and Shoring
................................
...
16 6.2.3
Subgrade Preparation
................................
................................
...........................
17 6.2.4
Materials for Fill
................................
................................
................................
....
17 6.2.5
Engineered Fill Placement and Compaction
................................
.........................
18 6.2.6
Utility Trench Backfill
................................
................................
............................
18
6.2.7 Considerations for Soil Moisture and Seepage Control ................................
........
19 6.2.8
Wet Weather Construction
................................
................................
...................
19 6.3
FOUNDATIONS
................................
................................
................................
..................
19 6.3.1
General
................................
................................
................................
..................
19 6.3.2
Post
-
tensioned Slabs (Residential Buildings)
................................
........................
20 6.3.3
Structural Mats (Commercial Buildings)
................................
...............................
21 6.3.4
Grid Foundations (Commercial Buildings)
................................
............................
21 6.3.5
Conventional Footings (Retaining Walls, etc.)
................................
......................
22 6.4
CONCRETE SLABS
-
ON
-
GR
ADE
................................
................................
...........................
23 6.4.1
Interior Slabs
-
on
-
grade
................................
................................
.........................
23 6.4.2
Exterior Concrete Slabs
-
on
-
grade
................................
................................
.........
23 6.5
RETAINING WALLS
................................
................................
................................
............
24 6.6
VEHICLE PAVEMENTS
................................
................................
................................
........
25 6.7
SURFACE AND SUBSURFA
CE DRAINAGE
................................
................................
...........
26 6.8
STITCH PIERS ALONG E
XISTING CREEK BANK
................................
................................
...
26 7
PLAN REVIEW, EARTHWO
RK AND FOUNDATION OB
SERVATION
................................
.....
28 8
LIMITATIONS
................................
................................
................................
.................
29 Figures
Figure
1 Site
Plan
–
Existing
Development
Figure 2
Site Plan
–
Proposed Deve
lopment
Figure 3
Locations of Project Site and Zone 7 Monitoring Well 16P5
Figure 4
Depth to Groundwater, Zone 7 Well 16P5
Figure 5
Recommended Building Setback
Figure
6 Post
-
tensioned Slab
Typical Section
Appendix A
-
K
eys
to Soil Classification
,
Drill Hole Logs
, and CPT Plots
Keys to Soil Classification (Fine and Coarse Grained Soils)
Log of Exploratory Drill Holes (DH
-
1 through
DH
-
4 )
CPT
Plots
(CPT
-
1 through CPT
-
3)
Appendix
B
–
Laborato
r
y Test Data
Figure
B
-
1 Atterberg Limits
Summary Repor
t
Figure B
-
2 Particle Size Analysis Test Report
Figure
B
-
3 R
-
value Test Result
CERCO Analytical
Report and
Test Results
Appendix C
–
Results of
Liquefaction Analyses
Appendix
D
–
Results of Slope Stability and Lateral Deformation Analys e
s
Geotechnical
Study
475 & 493 St. John Street, Pleasanton,
California
Project
PA20.1055.00
1 June
2 , 2022
1 INTRODUCTION
This report presents
the results of
our geotechnical
study
for
the
proposed
residential
development
on
two adjoining parcels located at 475 and 493 St. John Street in Pleasanton ,
California.
The combined area of the two parcels is approximate
ly
2.3 acres.
The
Assessor Parcel
Number
s
of the parcels are 94
-
114
-
7 and 94
-
114
-
8 .
The
combined
parcel
s
are
referenced as the
“property,” “site,” or “project
area
” in this report.
The approximate location of the
project site
is shown on the Vicinity Ma
p included
with
Figure
s
1 and 2
of this report
.
Figure
1 shows
a layout
of the
existing
site
conditions
.
Figure 2 shows a layout of the
currently
proposed development
.
This report presents our
findings,
conclusions
,
and geotechnical recommendations for
design and
construction
of the project
. These
findings,
conclusions
,
and recommendations are based on
information collected
and reviewed
during
this
study
.
The conclusions and recommendations in
this report should not be extrapolated to other areas or us ed for other projects without our
review.
This report also addresses comments from the City of Pleasanton (City) in their review letter dated February 25, 2022, and discussions in a meeting between the City, Robson Homes (
project
developer
)
,
Ruggeri
Jensen Azar (RJA, project civil engineer)
, and
our firm (
project geotechnical
engineer
)
on March
15, 2022.
1.1 P
roject
D
escription
The 475 St. John Street parcel is currently occupied by the Barone’s Restaurant
building in the
southern
portion
and t
he 493 St. John Street parcel is occupied by a residence in the southwestern portion
.
The northern approximately 90 to 100
feet of the two parcels are
occupied by the Arroyo del Valle
Creek
. The remainder of the 475
St. John Street
parcel is
occupied by
miscellaneous structures
,
patio
, and law
n
. The remainder of the 493
St.
John Street
parcel is occupied by
a paved parking lot
.
As presently planned, the existing residence will remain and the rest
of the site will be developed
wit
h
fourteen
single
-
family residential lots
(Lots 1 through 14)
and
a
commercial lot
(Lot
15)
.
Associated improvements will include paved on
-
site street
s
, underground utilities, and
landscaping. The proposed residential
buildings
with attached garages
will
each
be
a
two
-
story,
wood
-
framed
structure
with
a
basement
at about 5
feet below ground surface. The buildings will
be supported
on post
-
tensioned slab foundations
.
The
below
-
grade
perimeter building walls will
serv
e
as retaining walls. Other
site
r
eta
ining walls
,
if required,
will be limited to
landscaping
walls
on the order of 2
feet in height
.
The proposed commercial lot will be developed with two buildings
separated by
an open
plaza
.
The buildings will be constructed at grade
. These buildings wi
ll each be supported either on a
structural mat or a
grid f
oundation system with
conventional concrete
slab (see Section 4.4 of
this report)
.
Geotechnical
Study
475 & 493 St. John Street, Pleasanton,
California
Project
PA20.1055.00
2 June
2 , 2022
Preliminary grading
information
indicates site
grading will involve
fills
of
about 1 to
2 feet thick
and cuts
up to about 5 to 6 feet deep
to construct
the
building pads and to achieve design grades.
Deep
er
excavations may be necessary for construction of underground utilities.
The
current plan is to use hardscape in the backyards of Lots 8 through 14 with are a drains to
collect and direct storm water away from the creek behind these lots.
Stitch piers will
also
be
installed along the top of the existing creek bank
on these seven lots to
reduce the potential for
creek bank erosion
impacting
the proposed develo
pment.
These approaches are intended to
address the City’s review comment regarding creek bank erosion , and to allow the hardscape in
the backyards of Lots 8 through 14 extending to the stitch piers .
The above project descriptions are based on informati
on
provided
to us.
If the actual project
differs from th
ose
described above,
Geo
-
Logic Associates
(GLA)
should be contacted to review
our
findings,
conclusions
,
and recommendations and present any necessary modifications to address the different project d
evelopment
schemes
.
1.2 I
nformation Provided
For this investigation,
we were provided with the following by
Robson Homes
and
RJA
.
1. A 6
-
sheet set of drawings titled “Planned Unit Development, 475 and 493 Saint John Street, City of Pleasanton, Alameda County, California,” prepared by R JA
, dated
May
2 6
,
2022
.
2. A 7
-
sheet set of drawings titled “Vesting Tentative Map, Tract 8631 -
475 and 493 Saint
John Street, City of Pleasanton, County of Alameda, California,” prepared by R JA
,
dated
May
26, 2022.
1.3 P
urpose and Scope of Services
The purpose of
this
geotechnical
study
w
as
to explore subsurface conditions
at the
project
site
and to
provide
geotechnical recommendations for design and construction of the proposed improvements
.
The
following
work
was performed
.
1. Performed a
site reconnaissance to observe site surface conditions and to mark locations of our exploration
.
2. Reviewed
available
geologic
and geotechnical
information
pertinent to the site
.
3. Obtained a drilling permit from Zone 7 Wate
r District for our subsurface exploration.
4. Notified Underground Service Alert (USA)
for underground utility clearance and
coordination of our drilling with Robson Homes
.
Geotechnical
Study
475 & 493 St. John Street, Pleasanton,
California
Project
PA20.1055.00
3 June
2 , 2022
5. Subcontracted with a private underground locator
to
check the proposed exploration
l
ocation
s
for presence
of underground utilities.
6. Explored subsurface
conditions
by means of
four
exploratory
drill holes
and three cone
penetration test (CPT)
probes
to depth
s
between
approximately
20 and
50 feet below
ground surface
.
7. Collected
a
bulk sa
mple of the near
-
surface soil.
8. Performed laboratory tests on
selected soil samples from the
drill holes and on the bulk
sample
to
measure
pertinent engineering properties of the samples.
9. Performed engineering
analysis o
n
the field and laboratory data.
10. Prepar
ed
draft
geotechnical
study
report
s
.
11. Provided geotechnical consultation to our client.
12. Reviewed
and responded to
comments
in
the City of Pleasanton
review letter dated
February 25, 2022
.
13. Attended a
meeting with
the
City of Pleasanton Engineering Department
on March 15,
2022 to review the City review comments
.
14. Prepared this final geotechnical study report.
Geotechnical
Study
475 & 493 St. John Street, Pleasanton,
California
Project
PA20.1055.00
4 June
2 , 2022
2 SITE INVESTIGATION
Th
is
investigation consist
s
of
a
site reconnaissance and a subsurface expl
oration program. The
site reconnaissance was to observe existing site surface conditions. The subsurface exploration program
w
as
to explore
earth
conditions at the
project
site
.
The observed surface and subsurface
site conditions are discussed in Secti
o
n
3 of this report.
2.1 Subsurface Exploration
Our
geotechnical
subsurface exploration program
in
cluded
four exploratory drill holes (DH
-
1 through DH
-
4) and
three
CPT
probes
(CPT
-
1 through CPT
-
3 )
advanced on
November 13
, 20
20 .
The exploratory drill holes a
nd CPT probes were located in the field by referencing to existing site features and pacing; therefore, their locations are approximate. The se
approximate
exploration
locations are shown on Figures
1 and 2
of this report
. The drill holes and CPT
probes
w
ere
backfilled
in accordance with Zone
7 Water Agency guidelines
after completion of drilling and
testing.
2.1.1 Exploratory Drill Holes
The four exploratory drill holes were advanced using a truck -
mounted Mobile B
61 drill
ing
rig
equipped with 8
-
inch diameter h
ollow
-
stem augers. The depth of exploration ranged between
approximately
20 and
50 feet below ground surface (bgs). In the field, our personnel visually classified the materials encountered and maintained a log of each drill hole.
Soil samples were ob
tained using a 2
-
inch outside diameter (O.D.; 1.4
-
inch inside diameter, I.D.)
split
-
barrel sampler (also called a Standard Penetration Test sampler) and a 3 -
inch O.D. (2½
-
inch
I.D.) split
-
barrel sampler. Soil samples were obtained by driving the sampler u p to 18
inches into
the earth material using a 140
-
pound
automatic
trip
hammer falling 30
inches. The number of
blows required to drive the sampler was recorded for each 6 -
inch penetration interval. The
number of blows required to drive the sampler the l
ast 12
inches, or the penetration interval
indicated on the log when harder material was encountered, is shown as blows per foot (blow count) on the drill hole logs.
In the field, our personnel visually classified the materials encountered and maintai ned a log of
each drill hole. Visual classification of soils encountered in our drill holes was made in general accordance with the Unified Soil Classification System (ASTM D
2487 and D
2488). The results of
our laboratory tests were used to refine our f
ield classifications. Two Keys to Soil Classification, one for fine grained soils and one for coarse grained soils, are included in Appendix
A, together
with
our drill hole
logs.
2.1.2 Cone Penetration Test Probes
The
three
CPT probes
were performed by
Middle
Earth Geo Testing to
depth
s
between
approximately
30 and
50 feet bgs.
CPT involves pushing a small diameter
steel probe
(1
5 cm
2
Geotechnical
Study
475 & 493 St. John Street, Pleasanton,
California
Project
PA20.1055.00
5 June
2 , 2022
cross
-
sectional area
cone
was used for this project
) into the ground using a hydraulic jack
attached to a truck
-
mounted rig. T
he tip of the probe is instrumented and takes almost
continuous measurements (roughly every 1
inch) of tip resistance, side friction resistance, and
pore pressure.
Graphic presentations of the
CPT data are included in
Appendix
A of this report.
2.2 L
aborator
y Tes
ting
Geotechnical laboratory testing was conducted on selected soil samples collected from our drill holes. The
se
tests included moisture content
,
dry density,
Atterberg limits,
sieve analysis,
hydrometer,
and percentage passing a No.
200 sieve.
An
R
-
value test was performed on the bulk
sample
collected from the site
.
The laboratory test results are presented on the drill hole logs
at
the corresponding sample depths
. Graphic presentations of the results of the
Atterberg limits,
sieve analysis
,
hyd
rometer,
and R
-
value tests
are
presented
on separate sheets
in
Appendix B
In addition to geotechnical testing,
one
selected soil sample w
as
sent to CERCO Analytical for
corrosivity analysis. A brief report from CERCO Analytical with the corrosivity tes t results is
included in Appendix
B
.
Geotechnical
Study
475 & 493 St. John Street, Pleasanton,
California
Project
PA20.1055.00
6 June
2 , 2022
3 FINDINGS
3.1 S
urface Conditions
The 475 St. John Street parcel is currently occupied by the Barone’s Restaurant building in the southern
portion and the 493 St. John Street parcel is occupied by a residence in the southw
estern portion.
The northern approximately 90 to 100
feet of the two parcels are
occupied by the Arroyo del Valle
C
reek
(trending easterly
-
westerly)
. The remainder of the 475
St.
John Street parcel is occupied by
miscellaneous structures, patio, and lawn
. The remainder of
the 493
St.
John Street parcel is occupied by a paved parking lot.
Ground surface slopes down
gently from north to south with a vertical relief of
roughly
2 to 2.5 feet across the property.
There
are isolated mature trees.
The topo
graphic
information
prepared by RJA
indicates
the creek bank
along the northern
portion of the
two parcels is about 19 to 21
feet high
with inclination of roughly 1.5:1 to 2:1
(horizontal:vertical)
.
The creek appeared to be dry at the time of our site inv estigation in late
October 2020.
3.2 Subsurface Conditions
Subsurface soils encountered
in our drill holes
and CPT probes
can be generalized as
alluvium
. In
the four
drill holes
, a pavement section consisting of approximately
3 inches of asphalt concrete
ov
er approximately
4 inches of base
rock was encountered at the surface.
In DH
-
1, subsurface soils below the pavement section consist of very stiff sandy silt of low plasticity to a depth of about 4
feet bgs, stiff lean clay of low plasticity to a depth o f about 12
feet
bgs, and medium dense to dense poorly graded sand to the maximum explored depth of about 20 feet bgs.
In DH
-
2, subsurface soils below the pavement section consist of very stiff sandy silt of low plasticity to a depth of about
12 feet bgs,
very dense silty sand to a depth of about 17
feet bgs,
and
very
dense
well
graded sand
with gravel and clay
to the maximum explored depth of about
20 feet bgs.
In DH
-
3 , subsurface soils below the pavement section consist of st
i
ff to hard
sandy silt of low
plasticity to a depth of about
6 feet bgs,
dense poorly graded sand with clay to a depth of about
12 feet bgs, medium dense to dense well graded sand with gravel and clay to a depth of about
22.5 feet bgs, medium dense to very dense poorly graded sand wit h gravel and clay
to a depth of
about
48 feet bgs, and
dense to very
dense
well
graded
gravel with
sand
and clay
to the maximum
explored depth of about
5 0
feet bgs.
In DH
-
4 , subsurface soils below the pavement section consist of very stiff to hard
sandy s
ilt of low
plasticity to a depth of about
6 feet bgs,
and dense to very dense well graded sand with gravel
and clay to
the maximum explored depth of about 20
feet bgs.
Geotechnical
Study
475 & 493 St. John Street, Pleasanton,
California
Project
PA20.1055.00
7 June
2 , 2022
In CPT
-
1, the interpreted soil behavior type
s
consist of clayey silt to silty clay to a
depth of about
20 feet bgs, and layers of silty sand to sandy silt and clean sand to silty sand to the to the
maximum explored depth of approximately
50 feet bgs.
In CPT
-
2, the interpreted soil behavior type
s consist of clean sand to silty sand and clay
ey silt to
silty clay to a depth of about 6.5
feet bgs, and clean sand to silty sand
to the maximum explored
depth of approximately
30 feet bgs.
In CPT
-
3, the interpreted soil behavior type
s consist of
clean sand to silty sand
and clayey silt to
silty cl
ay to a depth of about 5.5
feet bgs, and clean sand to silty sand to
the maximum explored
depth of approximately
50 feet
bgs.
3.3 Groundwater
Groundwater was encountered
at a depth of about 48
feet bgs in DH
-
3 ,
CPT
-
1 ,
and CPT
-
3 at the
time of our exploratio
n
in November 2020
. Groundwater was not encountered in the other drill
holes and
CPT
-
2 because
they
did not extend to that depth
.
Based on groundwater level information
provided by Zone 7 Water Agency for
monitoring
well
16P5 (closest to the site), the
highest groundwater level was about 25 feet bgs
and the lowest
groundwater level was about 67
feet bgs
between October 8, 1976 and November 17, 2020
(Note: the well was dry
between
July 24 and October 5, 2014)
.
Figure
3 depicts t
he approximate
location o
f well 16P5 with respect to the subject site
. Figure
4 depicts the
recorded depth to
groundwater in well 16P5
in a graph.
It should be noted that f
luctuations in the groundwater level may occur due to seasonal variations in rainfall and temperature,
wate
r level in the adjacent creek,
pumping from wells,
regional groundwater recharge program,
irrigation
,
or other factors that were not evident at the
time of our investigation.
3.4 Variations in Subsurface Conditions
Our interpretations of soil and groundwa
ter conditions, as described
in this report
, are based on
information
obtained
during
this study.
Our
conclusions and recommendations are based on
th
e
se interpretations. Please
realize
the site has undergone
different phases of
development
and grading.
Therefore, it is likely that undisclosed variations in subsurface conditions exist at the site
, particularly
old foundations, abandoned utilities
,
and
areas of deep and loose fill.
C
areful observations
should
be made during construction to ver
ify our interpretations. Should
variations from our interpretations be found, we should be notified to evaluate whether any revisions should be made to our recommendations.
Geotechnical
Study
475 & 493 St. John Street, Pleasanton,
California
Project
PA20.1055.00
8 June
2 , 2022
4 SEISMIC CONSIDERATIONS
4.1 Earthquake Faulting
The Greater San Francisco Bay Area
is seismically dominated by the active San Andreas Fault s
ystem, the tectonic boundary between the northward moving Pacific Plate (west of the fault) and the North American Plate (east of the fault). This movement is distributed across a complex system o
f generally strike
-
slip, right
-
lateral, and subparallel faults.
Potential sources of significant earthquake ground shaking at the site include several active and potentially active faults in the
Greater
San Francisco Bay area, as well as faults farther af
ield. The
faults were first compiled on the State’s Fault Activity Map (Jennings, 1974; Jennings and Bryant, 2010). This map has now been integrated into the US Geological Survey’s Quaternary Fault and Fold Database and made available as a .kmz “drape” o
ver Google Earth terrain files.
The distance to a seismic source (fault) is defined by the NGA relationships as the closest distance to the seismogenic zone, be it in the subsurface or at the surface; distances may therefore differ from distances measur
ed on the ground surface. The distances shown on the table below are for reference only, as they are horizontal distances from the site to the surface trace of the seismic source, and not necessarily the closest distance to a (dipping) seismogenic zone.
These distances
were measured using the US Geological Survey’s Quaternary Fault and Fold Database, with major faults listed in approximate order of distance from the site; not all sources are listed in the summary table below.
Table 4.1
-
1 :
Distance and
Orientation to Nearby Faults
Fault
Name
Approximate Distance
Orientation from Site
Calaveras
(northern section)
3.5 km
Southwest
Hayward (south
ern section
)
13.6 km
Southwest
Greenville
16 km
Northeast
San Andreas
(Peninsula section)
43.8 km
Southwes
t
4.2 Ground Accelerations
According to the 201
9 California Building Code (CBC) and American Society of Civil Engineers (ASCE)
Standard 7
-
1 6
,
the spectral response acceleration at any period can be taken as the lesser of the spectral response accelerations
from the probabilistic and deterministic ground motion
approaches.
The U.S.
Seismic Design Maps
tool available
at the
Structural Engineers Association
of California (SEAOC)
website
was used
for this purpose to retrieve seismic design parameter
values for
design of buildings at the subject site. Two levels of ground motions are considered in the Application: Risk
-
targeted Maximum Considered Earthquake (MCE
R
) and Design Earthquake
(DE), with both probabilistic and deterministic values defined in terms of m aximum
-
direction
rather than geometric
-
mean, horizontal spectral acceleration
(S
a
)
. The probabilistic MCE
R
spectral response accelerations are represented by a 5
percent damped acceleration response
spectrum having a 1
percent probability of collapse with
in a 50
-
year period and in the direction
Geotechnical
Study
475 & 493 St. John Street, Pleasanton,
California
Project
PA20.1055.00
9 June
2 , 2022
of the maximum horizontal response. The probabilistic Design Earthquake (DE) S a
value at any
period can be taken as two
-
thirds of the MCE
R
S
a
value at the same period.
Using the
SEAOC
Seismic Design Maps
a
pplica
tion,
a site Class D, and
the latitude and longitude
of the
site
(latitude
37.664512
º
N, longitude
-
121.875365
º
W)
,
the calculated geometric mean
peak ground acceleration adjusted for site class effects (PGA M
) for the MCE
G
(Geometric Mean
Maximum Considere
d Earthquake)
is
0. 848
g
.
4.3 Seismicity
The
Working Group on California Earthquake Probabilities’ (W GCEP
)
estimates of the
probabilities of major earthquakes are now in their sixth iteration, with the greatest changes in approach being the inclusion of
multi
fold
rupture scenarios, in the progressive consideration of
more potential seismic sources, the possibility of earthquakes on unrecognized faults, and the inclusion of the notion of fault “readiness”. Current estimates (WGCEP, 2014) for the San Francisco
region indicate a 72% probability of a large (magnitude 6.7 or greater) earthquake in the San Francisco Bay area as a whole over the 30
-
year period beginning in 2014; this overall
probability is greater than the previous (WGCEP, 2007) probability of 63%, d ue mainly to the
inclusion of multi
-
fault rupture scenarios. The estimate for the Calaveras fault alone is 14.4% (revised up from the 7% presented by WGCEP, 2007); for the (northern) San Andreas fault alone,
27.4% (revised upward from the WGCEP (2007) val
ue of 21%); and for the Hayward fault, 45.3%
(revised upward from the WGCEP (2007) value of 31%).
4.4 Liquefaction
Soil liquefaction is a phenomenon in which saturated granular soils, and certain fine -
grained soils,
lose their strength due to build
-
up of ex
cess pore water pressure during cyclic loading, such as from
earthquakes. Soils most susceptible to liquefaction are saturated, clean, loose, fine -
grained
sands and non
-
plastic silts. Certain gravels, plastic silts, and clays are also susceptible to liqu
efaction. The primary factors affecting soil liquefaction include: 1)
intensity and duration of
seismic shaking; 2) soil type; 3) relative density of granular soils; 4)
moisture content and
plasticity of fine
-
grained soils; 5) overburden pressure; and 6)
depth to ground water.
Our review of the
California Geological Survey (CGS) Earthquake Zones of Required Investigation indicates the project area is located in a liquefaction hazard zone.
CPT
-
1 and CPT
-
3 were used
in
a site
-
specific liquefaction assessm
ent. Our liquefaction
assessment was based on a PGA value of 0.85g, earthquake moment magnitude of 7. 5 , and
a
groundwater
level
of
25 feet
bgs
. The results of our analysis
indicate
that
some of the
underlying
soils
may
liquefy when subject to shaking
of
the design earthquake.
The estimated
liquefaction
-
induced ground settlement
is roughly 2
inches
.
The
estimated
Liquefaction Potential Index
(LPI)
is about 4 to 6. For LPI between 0 and 5, the risk of liquefaction is low. For LP I
between 5 and
15, the r
isk of liquefaction is high. For LPI of 4 to 6, the risk of liquefaction may be interpreted as low to moderate.
The results of our liquefaction analysis are presented in Appendix C.
Geotechnical
Study
475 & 493 St. John Street, Pleasanton,
California
Project
PA20.1055.00
10 June
2 , 2022
For comparison purposes, we have also evaluated the liquefaction potent ial for groundwater at
a depth of
40 feet bgs,
the
average groundwater level
from
the
data provided by Zone
7 Water
Agency
.
For groundwater level at
4 0
feet bgs, the estimated liquefaction
-
induced ground
settlement
is roughly 3/4
to
1 inch
and the estimat
ed LPI is less than 2.6
.
Please note that l
iquefaction
-
induced
ground
settlement
s
are
in addition to settlements caused
by building loads
.
The
groundwater level
used
in our liquefaction analysis
was
based on our review of
depth to
groundwater informati
on provided by Zone
7 Water Agency
fo
r monitoring well 16P5 (closest to
the
site)
between October
8, 1976 and November
17, 2020 (a period of 44
years).
Figure
3 depicts the
location of well
16P5
with respect to
the
project
site
and Figure
4 is a graphic
i
llustration of
the recorded depth to groundwater
in well 16P5
. According to the Zone
7 data,
the highest recorded groundwater level was about 25 feet bgs and the lowest recorded groundwater level was about 67
feet bgs
, excluding the period between
July
24 and October 5,
2014 during which the well was dry
.
Therefore, in our opinion, a groundwater depth of 25
feet
is reasonable to represent the high groundwater level in our liquefaction analysis.
Based on our past experience, we expect the post
-
tensioned
slab foundations proposed for
the
residential units of
this project can be designed to accommodate the estimated 2
inches of
total
liquefaction settlements
(predicted 1
inch of differential settlements)
.
We understand the
project structural engineer, Gou
vis Engineering,
will design
the post
-
tensioned
slabs
to
accommodate
the estimated total and differential
liquefaction
-
induced
settlements.
Post
-
tensioned slabs are not planned for the
proposed commercial
buildings. Foundation options
to mitigate the p
otential impact of soil liquefaction for the commercial buildings include structural mats or grid foundations as discussed in Section s
6.3.3 and 6.3.4
below
.
4.5 Lateral Spreading
and Creek Bank Stability
Lateral spreading is horizontal movement of soil tow
ard a free face, such as a creek bank, typically
associated with liquefaction. Liquefaction
-
induced lateral spreading can also occur on mild
slopes (flatter than 5%) underlain by loose sands and a shallow groundwater table. If liquefaction occurs, the un
saturated overburden soil can slide as intact blocks over the lower, liquefied deposit, creating fissures and scarps.
The potential for lateral spreading in general mirrors the potential for liquefaction, and the depth of the liquefiable soil layers with respect to the creek
banks.
To evaluate
stability of
the
creek bank and potential lateral spreading magnitude, we performed a static and pseudo
-
static slope stability analysis using the computer program SLOPE/W.
The soil
properties used in our analysis
were developed using our drill hole and CPT
data
and are shown
in
Table 4.5
-
1 below.
Geotechnical
Study
475 & 493 St. John Street, Pleasanton,
California
Project
PA20.1055.00
11 June
2 , 2022
Table 4.5
-
1: Soil Properties for Slope Stability Analysis
Depth Below
Ground Surface
(feet)
Soil
Static
Analysis
Pseudo
-
static
Analysis
Cohesion
(psf)
Friction Angl
e
(degrees)
Cohesion
(psf)
Friction Angle
(degrees)
0 –
6 Sandy Silt
100
25 2000
0 6
–
25 Sand & Gravel
0 36
0 36
25 –
35 Sand & Gravel
0 36
1500*
0 35
–
47 Sand & Gravel
0 36
2400*
0 47
-
50 Sand & Gravel
0 36
800*
0 * Estimated residual shear stren
gth for liquefi
able
soils.
The minimum static and pseudo
-
static factors of safety with respect to sliding were calculated on
a 21
-
foot high creek bank
inclined at
1.5:1 and 2:1
(horizontal:vertical). The results of our analysis
are
shown in Table 4.5
-
2 below.
Table 4.5
-
2: Factor of Safety from Slope Stability Analysis
Bank Inclination
Factor of Safety
Static, GW @
El. 327
ft
(1)
Static, GW @
El. 342
ft
(1
,2
)
Pseudo
-
static
, GW @
El. 327 ft
(
3 )
1.5:1 (h:v)
1. 3
1. 2
1.04 2:1 (h:v)
1.7 1.
5 1.09
Notes:
1. T
op of
creek bank
at
elevation 352 feet.
2. 100
-
year design flood elevation of 342 feet provided by project civil engineer.
3. A seismic coefficient of 0.25 was used in the pseudo -
static analysis.
As shown in Table 4.5
-
2 above,
the
calculated
factor
of safety (
FS) of the creek bank
inclined
at
1.5:1 (h:v) is
1.2 to
1.3, below the minimum
acceptable
FS of 1.5. For creek bank
inclined at
2:1
(h:v), the FS is about
1.5 to
1.7 for static conditions and 1.
09 for pseudo
-
static conditions
.
The
results of our slope st
ability analysis are presented in Appendix D.
The results of our slope stability analysis also suggest that sloughing of the creek bank surficial soil may occur.
Sloughing may occur naturally due to weight of the material, during water flow in the cree
k,
or
as a result of seismic shaking.
This is
common
for slopes consisting of granular
soil with little or no fines.
To
estimate the probable
lateral displacements of the creek bank during seismic events, we performed a
seismic slope displacement
analysi
s
following the Bray & Travasarou (2007)
procedures. The analysis was based on the failure circle with a factor of safety of roughly
unity
(FS
≈
1)
and
a seismic velocity of 350 m/s estimated
from
the CPT data
. The results of our analysis
suggest the probable lateral displacement near the top of the creek bank would be on the order of 8
inches under the design earthquake.
Refer to
S
ection
6.1 of this report for recommended maximum creek bank inclination and minimum set back distance from crest of creek bank for structures
and improvements
and
Geotechnical
Study
475 & 493 St. John Street, Pleasanton,
California
Project
PA20.1055.00
12 June
2 , 2022
Section
6.8 for stitch piers information
.
4.6 S
eismic Design Parameters
Design of the proposed structures should comply with design for structures located in seismically
active areas.
Structures should be designed in accordance with the requirements of governing jurisdictions and applicable building codes.
GLA evaluated ASCE 7
-
16 seismic design parameters
for the site using the SEAOC U.S. Design Maps application.
The t
able below lists the seismic
design parameters for the site.
Note that, because the Mapped Spectral Acceleration at 1.0 -
second Period (S
1 ) value for the site is larger than 0.2 g, a site response analysis may be required ,
in accordance with Section 11.4.8
of ASCE 7
-
16. Table 4.6
-
1: Seismic Design Parameters Based on 2019 CBC & ASCE 7 -
16 Seismic Design Parameter
Value
Site Class
D
Site Coefficient, F
a
1.0 Site Coefficient, F
v
1.7 Mapped Spectral Acceleration at 0.2
-
second Period, S
s
1.85 g
Mapped Sp
ectral Acceleration at 1.0
-
second Period, S
1 0.68 g
Spectral Acceleration at 0.2
-
second Period Adjusted for Site Class, S
MS
1.85 g
Spectral Acceleration at 1.0
-
second Period Adjusted for Site Class, S
M1
1.16 g
Design Spectral Response Acceleration at 0.
2 -
second Period, S
DS
1.23 g
Design Spectral Response Acceleration at 1.0
-
second Period, S
D1
0.77 g
Long
-
period Transition Period, T
L
8 sec.
Note:
The site
w
ould be Site Class
F because it is underlain by liquefiable soils. But
if the
fundamental period
of
vibration of the structure
s
is
equal to or
less than 0.5
second, the Site Class can be determined by assuming there is no liquefaction (ASCE 7
-
16 Section
20.3.1). Therefore, Site Class D was selected for this project . If the
fundamental period of vib
ration of the structures is larger than 0.5 second,
contact our office
for a site
-
specific
seismic response analysis.
Geotechnical
Study
475 & 493 St. John Street, Pleasanton,
California
Project
PA20.1055.00
13 June
2 , 2022
5 DISCUSSION AND
CONCLUSIONS
Based on
our geotechnical evaluation
, it is our opinion the
project
site
may be developed as
discussed in thi
s report
,
provided
our geotechnical
recommendations are incorporated in
the
design and construction
of the project
. Our opinion
s
, conclusions
,
and recommendations are
based on our
understanding of the proposed development,
data review,
properties of soils
encountered in
subsurface exploration
, laboratory test
results
, and
engineering analyses
.
Geotechnical considerations
for this project
are discussed below.
5.1 Ground Rupture
The project site is not located in an Alquist
-
Priolo Earthquake Fault Zone. Bec
ause no active or
potentially active faults are known to cross the
site
, it is reasonable to conclude
that
the risk of
fault rupture
through the project site
is low.
5.2 Seismic Shaking
The
project site
is located in an area of high seismicity. Based on
general knowledge of the site
seismicity, it should be anticipated that, during their useful life, the proposed structures will be subject to at least one severe earthquake (magnitude 7 to 8+) that could cause considerable ground shaking at the
site
. It i
s also anticipated that the
site
will periodically experience small to
moderate magnitude earthquakes.
5.3 Liquefaction
The results of our liquefaction analysis indicate that some of the
subsurface soils are
prone
to
liquefaction when subject to seismic sh
aking. The estimated liquefaction
-
induced
total
ground
settlements are on the order of 2
inches.
The potential differential settlements would be on the
order of 1
inch
.
The proposed residential buildings will be supported on post -
tensioned slab
foundati
ons and the proposed commercial buildings will be supported on either structural mats or grid foundation systems.
We understand the project structural engineer will design the
foundations
to accommodate the estimated seismic settlement
plus static settlem
ent from
building loads
(less than 1
inch)
.
5.4 Slope Stability and Lateral Deformations
The results of our slope stability analysis indicate the calculated
factor of safety
(FS)
of
t
he creek
bank at
an
inclination of 1.5:1 (h:v) is
1.3,
below the
minimum a
cceptable
FS
of 1.5.
For creek
bank inclination of 2:1 (h:v), the FS is about 1.7 for static conditions and 1. 09 for pseudo
-
static
conditions (seismic coefficient of
0.25 ).
At
the
100
-
year
flood
water
elevation of 342 feet, the FS
is 1.2 for
creek bank i
nclination
at
1.5:1 (H
:
V) and 1.5 for
creek bank inclination
at
2:1 (H:V).
Stability of the creek bank under earthquake loading
and 100
-
year flood
condition was not
considered because of the low probability of earthquake coinciding with periods of high wa ter
(U.S. Army Corps of Engineers Engineer Manual EM 11102
-
1913, 2000).
Geotechnical
Study
475 & 493 St. John Street, Pleasanton,
California
Project
PA20.1055.00
14 June
2 , 2022
The results of our lateral deformation analysis of the creek bank indicate a lateral displacement of about 8
inches near the top of the creek bank.
The stitch piers to be installed
along the top of
the existing creek
bank
would
provide
additional lateral resistance to help reduce potential
lateral displacement of soil behind the stitch piers.
The current plan is to use hardscape in the backyards of Lots 8 through 14 with area drain s to
collect and direct storm water away from the creek behind these lots. This approach should help reduce infiltration of storm water into the soil behind the creek bank which could impact creek bank stability.
R
efer to the
S
ection
6.1 of this repo
rt regarding
maximum
creek bank inclination and
minimum
horizontal
set
-
back distance
from the
crest of creek bank
for
the proposed
structures
and
improvements
.
5.5 Creek Bank Erosion
As discussed in Section 4.5 above, sloughing of the creek bank surficial soil may occur
,
especially
in the
relatively clean
granular
sand and gravel
soil
s
in the lower portion of the creek bank
.
During
the
meeting with the City on March
15, 2022,
the use of sheet piles, stitch piers, or other
appropriate means to protect the c
reek bank from fut
ure
erosion
was discussed
.
The
City
stated
their preference for stitch piers
because of the undesirable impact of installing sheet piles including the size of equipment
,
and
noise and vibration associated with driving sheet piles.
Sti
tch piers will be installed along the top of the existing creek bank on Lot 8 through 14 to reduce the potential for creek bank erosion impacting the backyards of these lots.
The stitch piers are
not intended to prevent erosion of the creek bank
soil in f
ront of the piers
.
The stitch piers,
together with the hardscape and area drains discussed in the section above, are intended to address the City’s review comment regarding creek bank erosion, and to allow the hardscape in the backyards of Lots 8 through
14 to extend to the stitch piers.
Stitch piers
sho
uld
consist of
d
rilled, cast
-
in
-
place, reinforced concrete
piers
.
Refer to Section 6.8 below for recommendations
for design of the stitch piers.
5.6 Expansion Potential of Surficial Soils
The surface and
near
-
surface soils encountered in our drill holes consist generally of silty sand with gravel. These granular soils have a low expansion potential; t herefore, soil expansion should
not be a
significant
concern at this site.
5.7 Existing Improvements
Existin
g improvements at the site include
miscellaneous structures, sheds,
trailers,
containers,
underground utilities
, isolated trees, and
possibly old
wells,
septic tanks
,
and leach fields
.
Prior
to construction, the existing structures and improvements should
be removed and the resulting
Geotechnical
Study
475 & 493 St. John Street, Pleasanton,
California
Project
PA20.1055.00
15 June
2 , 2022
excavations should be properly backfilled
with engineered fill
under the observation
and testing
of the project Geotechnical Engineer.
Geotechnical
Study
475 & 493 St. John Street, Pleasanton,
California
Project
PA20.1055.00
16 June
2 , 2022
6 GEOTECHNICAL RECOMMENDATIONS
6.1 Building Set
-
back
The inclinat
ion of the existing creek bank
along Lots
8 through 14
is between
roughly
1.5:1
(h:v)
and 1.9:1
(h:v)
, with an average of
about
1.6:1 (h:v)
. For this project,
b
uildings sh
ould be set back
at least 10
feet beyond
the crest of
the
projected
2:1 (h:v)
bank
from the toe of the existing creek
bank
, as
shown in Figure
5 of this report
.
S
titch piers
will be
installed
along the top
of the existing creek bank
; therefore,
the
e
xterior
concrete slabs in the backyards of Lots 8 through 14
may extend to the
stitch piers
.
Our review of
the Preliminary Grading and Drainage Plan prepared by RJA, dated May
26, 2022,
included in the Vesting Tentative Map package,
indicate
s
the proposed
houses
on
Lots 8 through
14 will be
locat
ed at least 20 feet from the top of the existing creek bank, per
City
’s
review letter
dated February
25, 2022.
Based on our
assessment
, this
20 -
foot
setback
from top of existing
creek bank
meet
s
our recommen
ded
10 -
foot
setback
from the crest of the
projected
2:1 (h
:v)
bank from existing toe of bank
.
6.2 Earthwork
6.2.1 Site
Preparation,
Clearing and Stripping
Prior to grading, construction areas should be cleared of all structures
and foundations
,
obstructions
,
de
leterious materials, abandoned or designated utility lines, designated trees,
and
other below grade obstacles encountered during the clearing operation.
Tree stumps should be
grubbed.
Roots
with diameter of
about 1
inch or larger
or length of
about 3
fee
t or longer should
be removed.
Depressions, excavations
,
and holes that extend below the planned finish grades
should be cleaned and backfilled with engineered fill compacted to the requirements given under the section of
"
Engineered
Fill Placement and Co
mpaction."
After clearing,
the site s
hould be stripped to sufficient depth to remove vegetation and organic -
laden topsoil. Stripped material may be stockpiled for use in landscape areas if approved by the project landscape architect
;
otherwise
, it should
be
removed from the site.
For planning
purposes, an estimated stripping depth of
2 to
4 inches may be assumed
in unpaved areas
.
The
actual
stripping depth should be determined in the field by the Geotechnical Engineer at the time of construction.
6.2.2 Excav
ation,
Temporary Construction Slopes,
and
Shoring
Excavations for this project are expected to include
demolition excavations,
over
-
excavation of
loose and disturbed soils,
cuts to achieve design grades
and to construct the basements
,
trenching to constru
ct new underground utilities
, and foundation excavations
. Excavations and
temporary construction slopes should be constructed in accordance with the current CAL -
OSHA
Geotechnical
Study
475 & 493 St. John Street, Pleasanton,
California
Project
PA20.1055.00
17 June
2 , 2022
safety standards and local jurisdiction. The stability and safety of excavations, braced
or
unbraced, is the responsibility of the contractor.
Care should be exercised when excavating in
the proximity of existing structures and
improvements
.
Contractors are responsible for the design, installation, maintenance ,
and removal of temporary
sh
oring and bracing systems. The presence of existing structures, pavements, and underground utilities must be incorporated in the design of the shoring and bracing systems.
Trench excavations
adjacent to existing or proposed foundations should be above an imaginary
plane
having an inclination of 1
½:1 (
horizontal to vertical
) extending down from the bottom edge
of the foundations.
6.2.3 Subgrade Preparation
In areas to receive engineered fills,
foundation
s, concrete slabs
-
on
-
grade
, and pavements,
the
subgrad
e
soil
s
should be scarified
to a depth of
12 inches
,
moisture
-
conditioned
,
and compacted
in accordance with the recommendations given in
the
"
Engineered
Fill Placement and
Compaction"
section below.
In
building and
concrete slab
-
on
-
grade
areas
, subgrade p
reparation
should extend
a minimum of
5 feet
horizontally
beyond the limits of the proposed structures and
any adjoining flatwork
, unless it is restricted by existing improvements
. I
n pavement areas
,
subgrade preparation should
extend a
minimum of 3
feet
beyond the back of the curbs or
pavements.
Prepared soil subgrades should be non
-
yielding when proof
-
rolled by a fully loaded water truck
or similar weight equipment. Moisture conditioning of subgrade soils should consist of adding water if the soils are
too dry and allowing the soils to dry if the soils are too wet. After the subgrades are properly prepared, the areas may be raised to design grades by placement of engineered fill.
Wet soils should be anticipated during and after rainy months. Where encountered, u
nstable,
wet or soft soil will require processing before compaction can be achieved. If construction schedule does not allow for air
-
drying, other means such as lime or cement treatment of the soil or excavation and replacement with suitable
material may be considered. Geotextile fabrics may
also be used to help stabilize the subgrade. The method to be used should be determined at the time of construction based on the actual site conditions. We recommend obtaining unit prices for subgrade
stabilization during the construction bid process.
6.2.4 Material
s
for Fill
In general, on
-
site soils with an organic content of less than 3 percent by weight ,
free of
deleterious materials or hazardous substances
, and meeting the gradation requirements below
m
ay be used as engineered fill except where special material
is re
quired
.
Engineered fill material should not contain rocks or lumps larger than 3 inches in greatest
Geotechnical
Study
475 & 493 St. John Street, Pleasanton,
California
Project
PA20.1055.00
18 June
2 , 2022
dimension, should not contain more than 15 percent of the material larger than 1½
inches
, and
should contain at least 20 percent passing the No. 200 sieve. In addition to these requirements, import fill should have a low expansion potential as indicated by Plasticity Index of 15 or less
(per
ASTM D4318)
, or Expansion Index of less than 20
(p
er ASTM D4829)
.
All fills should be approved by the project
G
eotechnical
E
ngineer prior to delivery to the site. At
least
5 working days prior to importing to the site, a representative sample of the proposed import fill should be delivered to our la
boratory for evaluation.
Import fills should be tested and
approved for residential use per the California Department of Toxic Substances Control (DTSC) guidelines.
6.2.5 Engineered
Fill Placement and Compaction
Engineered fill should be placed in horizontal l
ifts each not exceeding 8 inches in thickness,
moisture conditioned to the required moisture content, and mechanically compacted to the recommendations below. Relative compaction or compaction is defined as the in -
place dry
density of the compacted soil d
ivided by the laboratory maximum dry density as determined by ASTM Test Method D1557, latest edition, expressed as a percentage. Moisture conditioning of soils should consist of adding water to the soils if they are too dry and allowing the soils to dry i f
they are too wet.
Engineered fills
consisting of
on
-
site or imported
soils
should be compacted
to
at least
90 percent
relative compaction with moisture content between about 1 and 3
percent above the laboratory
optimum value. In pavement areas, the u
pper 8
inches of subgrade soil should be compacted to
a minimum of 95 percent relative compaction
. Aggregate base in vehicle pavement areas should
be compacted at slightly above the optimum moisture content to a minimum of 95
percent
relative compaction.
6.2.6 Utility
Trench Backfill
Backfilling
of utility trenches in public right
-
of
-
way and street areas should comply with City of
Pleasanton Standard Specifications and Details, November 2016.
Backfilling of utility trenches in private areas may consist of pip e
bedding extending from the
bottom of the trench to about 1 foot above the top of pipe
and backfill material above. Pipe
bedding
may consist of free
-
draining sand (less than 5% passing a No.
200 sieve), lean concrete
or sand cement slurry. Sand, if used
as bedding, should be compacted to a minimum of 90
percent relative compaction.
Above the pipe bedding, utility trenches may be backfilled with on -
site soil or imported soil.
Trench backfill above the pipe bedding should be compacted to the requiremen ts given in the
section of “Engineered Fill Placement and Compaction.” Trench backfill should be capped with at least 12
inches of compacted, on
-
site soil similar to that of the adjoining subgrade. The backfill material should be placed in lifts not exce
eding about 6
inches in uncompacted thickness.
Geotechnical
Study
475 & 493 St. John Street, Pleasanton,
California
Project
PA20.1055.00
19 June
2 , 2022
Thinner lifts may be necessary to achieve the recommended level of compaction of the backfill due to equipment limitations. Compaction should be performed by mechanical means only.
Water jetting or flooding
to attain compaction of backfill should not be permitted.
6.2.7 Considerations for Soil Moisture and Seepage Control
Subgrade soil and engineered fill should be compacted at moisture content meeting our recommendations. Consideration should be given to reduci ng the potential for water infiltration
from the exterior to under the buildings through utility lines crossing the building perimeter. In utility lines crossing beneath perimeter foundations, permeable backfill should be terminated at least 1
foot outsid
e of the perimeter foundation. Impermeable material, such as concrete or clay soil, should be used for the entire trench depth to act as a seepage cutoff.
Where concrete slabs or pavements abut against landscaped areas, the base rock layer and subgrade
soil should be protected against saturation. Water if allowed to seep into the subgrade soil or pavement section could reduce the service life of the improvements. Methods that may be considered to reduce infiltration of water include: 1) subdrains inst alled behind curbs and
slabs in landscape areas; 2) vertical cut
-
offs, such as a deepened curb section, or equivalent,
extending at least 2 inches into the subgrade soil; and 3) use of a drip or controlled irrigation system for landscape watering.
6.2.8 Wet Wea
ther Construction
If site grading and construction is to be performed during the winter rainy months, the owner and contractors should be fully aware of the potential impact of wet weather. Rainstorms can cause delay to construction and damage to previous
ly completed work by saturating compacted
pads or subgrades, or flooding excavations.
Earthwork during rainy months will require extra effort and caution by the contractors. The contractor
s
are
responsible
for
protect
ing
their
work to avoid damage by r
ainwater. Standing
pools of water should be pumped out immediately. Construction during wet weather conditions should be addressed in the project construction bid documents and/or specifications. We recommend the contractor
s
submit a wet weather constru
ction plan outlining procedures they
will employ to protect their work and to minimize damage to their work by rainstorms.
6.3 Foundations
6.3.1 General
The Geotechnical Engineer
should
review the foundation plans and details before construction and
observe the f
oundation excavations
during construction
to determine if the
foundation
excavations extend into suitable bearing material.
Prior to placement of concrete, foundation
excavations should be cleaned of loose soils.
If unsuitable soils are encountered in th
e
foundation excavations, the soils should be removed as recommended by our
G
eotechnical
Geotechnical
Study
475 & 493 St. John Street, Pleasanton,
California
Project
PA20.1055.00
20 June
2 , 2022
E
ngineer and replaced with approved material such as compacted engineered fill or lean concrete.
Fo
undation
excavations should not be allowed to dry before placement of concrete. If visible
cracks appear in the
foundation
excavations, the excavations should be thoroughly moisture conditioned beginning at least
2 days prior to placement of concrete to close all cracks. It is also important that the base of the
foundat
ion
excavations not be allowed to become excessively wet,
resulting in soft soils. Water should not be allowed to pond in the bottom of the excavations.
Areas
that
become water damaged should be over
-
excavated to a firm base. The
foundation
excavations
should be monitored by
our
representative for compliance with appropriate
moisture control and to confirm the adequacy of the bearing materials.
6.3.2 Post
-
tensioned Slabs
(
Residential
Buildings)
The proposed residential structures may be supported on post -
tens
ioned (PT) slab foundations
bearing on properly moisture
-
conditioned and compacted soil subgrades. Preparation of soil subgrade, moisture conditioning, and compaction of soil and engineered fill should be as recommended in the “Earthwork” section
(Section
6.2)
of this report.
The
following
parameters
may be used with the 2004 PTI “Design of Post
-
Tensioned Slabs
-
on
-
Ground, Third Edition” manual for design of the PT slabs.
Table 6.3.2
-
1:
Parameters for Design of Post
-
tensioned
Slabs Constructed on
Nativ
e
Subgrade Soil
Parameters
Scenario 1
–
PT on native soil
Scenario 2
–
PT with
effects from
liquefaction
-
induced settlements
e
m
(center lift)
9 feet
9 feet
e
m
(edge lift)
5 feet
9 feet
y
m
(center lift)
0.25 inch
2 inches
y
m
(edge lift)
0. 2
5 inch
2 inc
hes
Allowable soil bearing pressure = 2,000 psf for dead plus live loads, with a one -
third increase
when including transient loads, such as wind or seismic
A deepened edge
, minimum 6 inches wide,
should be constructed along the perimeter of the PT
slabs
. The deepened edge should extend to at least 18
inches below the bottom of the PT slabs.
The deepened edge can help reduce moisture infiltration to under the PT slabs.
Where interior building grades are higher than the exterior grades, the perimeter foundation
elements should be designed to resist the lateral soil pressure and surcharge loads acting on the foundations. The bottom of the perimeter foundations should extend at least 18
inches below
the lowest finish grades, excluding landscaping soils
which are typically not compacted and
should not be considered for structural support.
We understand the PT slabs will be constructed on 1 to 2 inches of sand over a 15 -
mil visqueen
Geotechnical
Study
475 & 493 St. John Street, Pleasanton,
California
Project
PA20.1055.00
21 June
2 , 2022
vapor barrier over compacted subgrade soil. Sand has been used for prote ction of the vapor
barrier during construction and to allow dissipation of concrete mix water during curing. The use of sand, or equivalent material, should be determined by the project structural engineer or architect.
A lower water
-
cement ratio (0.45 t
o 0.50) will help reduce the permeability of the
concrete and, hence, vapor transmission through the
slab
s
.
Settlements
under building loads
are expected to be primarily elastic. Post construction total
and differential
settlement
s
of the PT slabs under
non
-
seismic conditions are
anticipated to be
less than
1 and ½
inch
, respectively
.
Refer to the “Liquefaction” section of this report for
additional
liquefaction
-
induced ground settlement.
6.3.3 Structural Mats
(Commercial Buildings)
The proposed commercial
buildings may each be supported on a structural mat foundation
bearing on properly moisture
-
conditioned and compacted soil subgrades.
Preparation of soil
subgrade, moisture conditioning, and compaction of soil and engineered fill should be as recommended
in the “Earthwork” section (Section 6.2) of this report.
The mats may be designed using a net allowable soil bearing pressure of 2 ,
0 00 psf
due to dead
plus live loads, with a one
-
third increase when including transient loads such as wind or seismic.
Th
e mats should have a thickness of at least 1
0 inches. A vertical modulus of subgrade reaction,
K
v1
, of
7 5 psi/in may be used in design of the mat.
Resistance to lateral loads may be developed from friction between the bottom of the
mats
and
the support
ing subgrade.
Mats
bearing on
undisturbed on
-
site soil
or engineered fill may be
designed using an ultimate friction coefficient of 0.
25 between the
mats
and supporting
subgrade
.
The mats should be designed for a total
post
-
construction settlement
of 2
inches,
with about
1 inch of differential settlement over a distance of about 25 feet
.
To reduce the potential
for
water infiltration from the exterior to under the mats, the perimeter of the mats
should
be thickened to serve as a water cut
-
off. The bot
tom of the thickened edges
should extend at least 18
inches below lowest adjacent finish grade and have a width of at least 6 inches. Please note the thickened edges are not intended to be structural elements of the mat foundations unless as designed by t
he structural engineer.
6.3.4 Grid Foundatio
ns (Commercial Buildings)
In lieu of structural mats, the proposed commercial buildings
may
each
be supported on a
grid
foundation
system
consisting
of
structurally
interconnected continuous footings
in a grid patte
rn
(isolated footings are not recommended).
The foundations should bear
on
engineered fill or
undisturbed on
-
site soil.
Preparation of soil subgrade, moisture conditioning, and compaction of soil and engineered fill should be as recommended in the “Earth work” section (Section 6.2) of
Geotechnical
Study
475 & 493 St. John Street, Pleasanton,
California
Project
PA20.1055.00
22 June
2 , 2022
this report.
The continuous footings may be designed for a net allowable bearing pressure of 3 ,000 pounds
per square foot
(psf)
due to dead plus live loads, with a one
-
third increase when including
transient loads such as
wind or seismic. The footing bottom should be at least 24 inches below
pad grade or lowest adjacent finish grade, whichever provides a deeper embedment.
Footings
should be at least 12
inches wide.
The continuous footings should be structurally interconn ected
to form a grid system for increase rigidity. Spacing between continuous footings should be
between 13 and 17
feet
, center to center
. Footings should be reinforced as determined by the
project Structural Engineer.
Resistance to lateral loads may be
developed from a combination of friction between the bottom of foundations and the supporting subgrade, and by passive resistance acting against the vertical sides of the foundations. Footings bearing on
native
soil or engineered fill may be designed usi
ng
an ultimate friction coefficient of 0
.3
between the foundations and supporting subgrade, and an ultimate passive resistance of
300
pounds per cubic foot (pcf, equivalent fluid weight) acting against the embedded sides of the foundations. The passive pr essure can be assumed to act
starting at the top of the lowest adjacent grade in paved areas. In unpaved areas, the passive pressure can be assumed to act starting at a depth of 1
foot below grade. It should be noted that
the passive resistance value dis
cussed above is only applicable where the concrete is placed directly against undisturbed soil or engineered fills. Voids created by the use of forms should be backfilled with property compacted engineered fill or with concrete.
The continuous footing sy
stems should be designed for a total
post
-
construction settlement
of
2 inches,
with about
1 inch of differential settlement over a distance of about 25 feet
.
To maintain the desired support, the bottom of footings adjacent to utility trenches or buried s
tructures should be below an imaginary plane having an inclination of 1.5 horizontal to 1 vertical, extending upward from the bottom edge of the adjacent utility trenches or structures. If the footings are closer than the recommended distance, the project
Geotechnical Engineer should
be consulted for recommendations.
6.3.5 Conventional
Footing
s
(Retaining Walls, etc.)
Footings, continuous
and
isolated, may be
used to
support
auxiliary
structures
such as site
retaining walls. Footings should bear on undisturbed
native soil and/or properly compacted
engineered fill.
Preparation of soil subgrade, moisture conditioning, and compaction of soil and engineered fill should be as recommended in the “Earthwork” section (Section 6.2)
of this report.
These f
ootings ma
y be designed
using the parameters given under Section 6.3.4 above except that the footing embedment depth may be reduced to
at least
18 inches below pad grade or
lowest adjacent finish grade, whichever provides a deeper embedment.
Geotechnical
Study
475 & 493 St. John Street, Pleasanton,
California
Project
PA20.1055.00
23 June
2 , 2022
6.4 Concrete Slabs
-
on
-
Grade
6.4.1 Interior Slabs
-
on
-
grade
The interi
or building slabs
of the residenti
al buildings
will be
the
post
-
tensioned
slabs.
If grid foundations are used for the commercial buildings, the building floors may consist of
conventional concrete slabs
-
on
-
grade.
Concrete slabs
-
on
-
grade should be
constructed over
proper
l
y
water
conditioned and compacted
subgrade
soil,
prepared per our recommendations
in
the “Earthwork” section
(Section 6.2) of this report.
Soil subgrades MUST be maintained in a
moist condition prior to placement of concrete for t
he concrete slabs. Design of reinforcement,
joint spacing, etc. is the responsibility of the design engineer.
Slabs that will be covered with moisture sensitive floor coverings or where vapor transmission through the slab is undesirable should be underla
in by at least 4
inches of capillary break material
such as free draining, ¾
-
inch by No.
4 clean crushed rock. A visqueen layer should be placed over the capillary break material. The visqueen should be a high -
quality polymer at least 15 mils thick
that
is resistant to puncture during slab construction. Laps between sheets and openings should be taped. Typically, the membrane and the slab are separated by 2
inches of sand but this should
be determined by the structural engineer and architect.
A lower
water
-
cement ratio (0.45 to 0.50) will also help reduce the permeability of the floor slab.
It should be understood that the recommended plastic membrane is not intended to waterproof the concrete slab floor. If waterproofing is desired, the project des igners and/or a flooring expert
should be contacted.
6.4.2 Ex
terior Concrete Slabs
-
on
-
grade
Exterior concrete
slabs
-
on
-
grade for this project will be limited to driveways and exterior flatwork. The
se
slabs should be constructed on
properly
moisture conditioned
and compacted
subgrade soil
as recommended in the “Earthwork” section
(Section 6.2)
of this report. Soil
subgrades
should
be maintained in a moist condition prior to placement of concrete for the concrete slabs.
Design of reinforcement, joint spacing, e
tc. is the responsibility of the design
engineer.
Exterior concrete slabs
-
on
-
grade should be cast free from adjacent f
oundations
or other non
-
heaving edge restraints. This may be accomplished by using a strip of 1/2 -
inch asphalt
-
impregnated felt divider
material between the slab edges and the adjacent structure. Frequent construction or control joints should be provided in all concrete slabs where cracking is objectionable. Continuous reinforcing or dowels at the construction and control joints will als o
aid in reducing uneven slab movements.
Geotechnical
Study
475 & 493 St. John Street, Pleasanton,
California
Project
PA20.1055.00
24 June
2 , 2022
6.5 Retaining Walls
Retaining walls
will include the basement perimeter walls about 5
feet high and
landscaping walls
with
exposed height
on the order of
2 feet.
Retaining walls should be designed to r
esist lateral
earth pressure and surcharge forces acting on the walls. Lateral pressures will depend on the degree of movement the walls are allowed (or desired), the type of backfill, the magnitude of external loads, and subsurface drainage provisions.
For static loading conditions, the walls may be designed using at -
rest or active soil pressure.
At
-
rest soil pressure should be used for walls where movement at the top of walls is restrained or undesirable
, such as the basement walls
. Wall movements c
ould cause settlement of backfill
and structures supported on the backfill. Active soil pressure may be used for retaining walls where the top of walls is free to deflect and resulting movement of the backfill is acceptable. The at
-
rest and active soil p
ressures given below are for level backfill surface
and
for either drained
or undrained backfill condition
.
Table 6.5
-
1: Recommended Lateral
Soil Pressures
(Equivalent F
luid Weights)
f
or Level Ground
Condition
Drained
Backfill
(1)
Undrained
Backfill
(2)
Active
(3)
45 pcf
8 2
pcf
At
-
rest
5 5 pcf
9 2
pcf
Seismic surcharge
(4)
2 8
pcf
2 8
pcf
Notes:
1. Lateral soil pressure
s
for drained
backfill may be used above
groundwater level with drainage provided
behind walls
.
2. Lateral soil pressures for undrained backfill should be used below groundwater level or where
drainage is not provided behind walls.
3. To develop active soi
l pressures, wall movements of about 0.005H to 0.01H may be necessary for cohesive soils, with up to 0.005H for cohesionless soils .
4. Seismic surcharge
, if required per building code
or structural design,
should be applied as an
inverted equivalent fluid p
ressure (inverted triangle) with the resultant force at 0.6H above the wall bottom (H is the height of the design plane from the wall bottom to the ground surface above).
Pressures due to static external loads should be added to the soil pressures recommended above in the
wall
design. For uniform vertical load at the ground surface, the additional lateral pressure
on the walls should be calculated as a uniform pressure equal to the magnitude of the vertical load multiplied by a factor. For level backfill slope, the factor is
0. 38
for active soil condition and
0.5 for at
-
rest soil condition. For ot
her slope inclinations and other types of surcharge loads, such as vehicle loads, point loads, strip loads, consult our office for specific recommendations.
Foundations for retaining walls may consist of footings designed using the reco
mmendations in
the
Foundations
Section 6.3.
5 of this report.
Wall Drain
s
(drained backfill condition)
:
For walls designed using lateral soil pressures under
drained backfill condition, a subsurface drain should be installed behind each wa ll extending from
Geotechnical
Study
475 & 493 St. John Street, Pleasanton,
California
Project
PA20.1055.00
25 June
2 , 2022
the wall bottom to about 1
foot below finished grade. The drain should consist of a 12 -
inch
minimum wide blanket of drainage material consisting of either Class
2 Permeable material
(Caltrans Standard Specifications, Section
68) or clean
, 1/2 to 3/4
-
inch maximum size crushed
rock or gravel. If crushed rock or gravel is used, it should be encapsulated in a geotextile filter fabric, such as Mirafi 140N or equivalent. Filter fabric is optional if Class 2 Permeable material is used. The to
p 1 foot below finish grade should be backfilled with compacted clayey soil to reduce infiltration of surface water.
A 4
-
inch minimum diameter, perforated, schedule 40 PVC (or equivalent) pipe should be installed (with perforations facing down) along the
base of each wall on a 2
-
inch thick bed of drain rock,
regardless whether drain rock or pre
-
fabricated drainage panel is used. The pipes should be sloped to drain by gravity to a proper collection system and be discharged at a proper outlet as designed by
the project Civil Engineer.
Wall Compaction
:
Backfill against retaining walls should be compacted as discussed in the “Earthwork” Section of this report. Over
-
compaction should be avoided because increased
compaction effort can result in lateral pressu
res significantly higher than those recommended
above. Backfill placed within 3
feet of the walls should be compacted with hand
-
operated
equipment.
6.6 V
ehicle Pavements
Vehicle pavements for this project
will
include
an
interior street
,
access drives
,
and
the
commercial
parking
lot
. These pavements will
primarily
serv
e
automobiles and light pickup
trucks, with occasional heavy vehicles, such as delivery and garbage trucks.
If the pavements are
constructed prior to completion of construction, the pavement s will be subject to construction
traffic including heavy delivery and concrete trucks.
An
R
-
value of
38 w
as
measured on
a
bulk sample of soil collected from the site. For design purposes,
an
R
-
value
of
2 5
was
used to calculate the pavemen
t sections ta
bulated below
using
the Caltrans pavement section design procedures
.
DESIGN TRAFFIC
INDEX
HOT MIX ASPHALT
(inches)
CLASS 2 AGGREGATE BASE
(inches)
TOTAL
(inches)
5.0 3.0
6.5 9.5
5.5 3.0
8 .0
11 .0
6.0 3.5
8 .5
1 2
.0
6.5 3.5
10 .0
1 3
.5
Pavement sections
should be constructed on soil subgrades that have been prepared as outlined in the “Earthwork” section of this report. The upper 8
inches of soil subgrade in pavement areas
should be compacted to a minimum of 9
5 percent relative compaction. The full sec
tion of
aggregate base
and aggregate subbase
should be compacted to a minimum of 95
percent relative
compaction. Evaluation of relative compaction should be based on ASTM D1557, latest edition.
Geotechnical
Study
475 & 493 St. John Street, Pleasanton,
California
Project
PA20.1055.00
26 June
2 , 2022
The Class 2 Aggregate Base material should conform to Sectio n 26 of the Caltrans Standard
Specifications
and the Class 2 Aggregate Subbase material should conform to Section
25 of the
Caltrans Standard Specifications.
6.7 S
urface and S
ubsurface D
rainage
Engineering design of grading and drainage at the site is the responsibility of the project Civil
Engineer. We suggest the following for consideration by the project Civil Engineer, as appropriate.
Sufficient surface drainage should be provided to direct water away from buildings, foundations, concrete slabs
-
on
-
gra
de and pavements, and towards suitable collection and discharge facilities.
Ponding of surface water should be avoided by establishing positive drainage away from all improvements.
6.8 Stitch Piers Along Existing Creek Bank
As discussed in Section 5.5 above
, stitch piers
will
be installed along the top of the existing creek
bank
.
Stitch piers should consist of d
rilled, cast
-
in
-
place, reinforced concrete
piers
.
Minimum
p
ier
diameter
should
be 24
inches.
Center to center spacing
between
piers should be
no more
than 2
times of the
pier diameter.
The upper portion of the stitch piers above the toe of creek bank elevation
sh
ould be designed to retain the soil and surcharge forces behind
the piers,
with
recommend
ations
in Section
6.5 “
Retaining Walls
”
above. Resistance to vertical and lateral load
s
sh
ould be from the lower portion of the piers below the toe of creek bank elevation
.
For
vertical
dead plus live loading, a net allowable
adhesion value of 500
pounds per square foot
may be assumed along the pier shafts.
This value may be increased by one
-
third when including
transient loads, such as wind or seismic.
The upper portion of the piers above
the bottom of
creek bank elevation
s
hould be ignored in the calculation of vertical pier capacity.
End bearing
capacity of the piers should also be ignored.
The lateral load capacity of a
stitch
pier is a function of the stiffness of the surrounding soils, the stiffness of the pier, the
allowable deflection at the top of the pier, the allowable moment capacity of the pier cross section, and the pier top connection (fixed head vs. free head).
Table
6. 8
-
1 below provides soil parameters
for use in
L
-
Pile
analysis of the stitch piers
.
Tab
le 6.
8 -
1 L
-
Pile Parameters for Drilled
Stitch
Piers
(1)
Depth Below Ground
Surface (feet)
L
-
Pile Soil
Type
SPT N
1,60
(blows/ft)
Ø
(degrees)
Cu
(psf)
Ɛ
50 K
(pci)
Unit Weight
(pcf)
Static Condition
0 –
21 Sand
neglect
---
---
---
---
---
21 –
25 (
2 )
Sand
60 36
0 ---
400
121
25 –
5 0
Sand
6 3
36 0
---
20 0
58 (3)
Liquefaction Condition
0 –
21 Sand
neglect
---
---
---
---
---
Geotechnical
Study
475 & 493 St. John Street, Pleasanton,
California
Project
PA20.1055.00
27 June
2 , 2022
Tab
le 6.
8 -
1 L
-
Pile Parameters for Drilled
Stitch
Piers
(1)
Depth Below Ground
Surface (feet)
L
-
Pile Soil
Type
SPT N
1,60
(blows/ft)
Ø
(degrees)
Cu
(psf)
Ɛ
50 K
(pci)
Unit Weight
(pcf)
21 –
25 (
2 )
Sand
---
0 1500
(4)
0.0071
200
121
25 –
50 Sand
---
0 2000
(4)
0.0063
250
58 (3)
Notes:
1. Parameters based on CPT
-
2 and CPT
-
3 .
2. Groundwater at 25 feet.
3. Buoyant unit weight below groundwater.
4. Undrained shear strength estimated by CLiq on CPT
-
2 and CPT
-
3. If water is encountered in the pier holes, concrete should be placed using the “tremie” method to displace the water to the su
rface.
Geotechnical
Study
475 & 493 St. John Street, Pleasanton,
California
Project
PA20.1055.00
28 June
2 , 2022
7 PLAN REVIEW, EARTHWORK AND FOUNDATION OBSERVATION
Post
-
report geotechnical services by Geo
-
Logic Associates (GLA), typically consisting of pre
-
construction design consultations and reviews
and
construction observation and testing services,
are nec
essary for GLA to confirm the recommendations contained in this report. This report is based on limited sampling and investigation, and by those constraints may not have discovered local anomalies or other varying conditions that may exist on the project site. Therefore, this
report is only preliminary until GLA can confirm that actual conditions in the ground conform to those anticipated in the report. Accordingly, as an integral part of this report, GLA recommends post
-
report
, construction related
geot
echnical services to assist the project team during design and construction of the project. GLA requires that it perform these services if it is to remain as the project
G
eotechnical
E
ngineer
-
of
-
record.
During design, GLA can provide consultation and s
upplemental recommendations to assist the
project team in design and value engineering, especially if the project design has been modified after completion of our report. It is impossible for us to anticipate every design scenario and use of construction
materials during preparation of our report. Therefore, retaining GLA to provide post
-
report consultation will help address design changes, answer questions and evaluate alternatives proposed by the project designers and contractors.
Prior to issuing pr
oject plans and specifications for construction bidding purposes, GLA should review the grading, drainage and foundation plans and the project specifications to determine if the intent of our recommendations has been incorporated in these documents. We ha ve found
that such a review process will help reduce the likelihood of misinterpretation of our recommendations which may cause construction delay and additional cost.
Construction phase services can include, among other things, the observation and testin g during
site clearing, stripping, excavation, mass grading, subgrade preparation, fill placement and compaction, backfill compaction, foundation construction and pavement construction activities.
Geo
-
Logic Associates would be pleased to provide cost pr
oposals for follow
-
up geotechnical
services. Post
-
report geotechnical services may include additional field and laboratory services.
Geotechnical
Study
475 & 493 St. John Street, Pleasanton,
California
Project
PA20.1055.00
29 June
2 , 2022
8 LIMITATIONS
In preparing the findings and professional opinions presented in this report, Geo -
Logic Associates
(GLA) has
endeavored to follow generally accepted principles and practices of the engineering geologic and geotechnical engineering professions in the area and at the time our services were performed. No warranty,
either
express or implied, is provided.
The concl
usions and recommendations contained in this report are based, in part, on information that has been provided to us. In the event that the general development concept or general location and type of structures are modified, our conclusions and recommendat ions shall not be
considered valid unless we are retained to review such changes and to make any necessary additions or changes to our recommendations. To remain as the project G
eotechnical
E
ngineer
-
of
-
record, GLA must be retained to provide geotechnical
services as discussed under
the Post
-
report Geotechnical Services section of this report.
Subsurface exploration is necessarily confined to selected locations and conditions may, and often do, vary between these locations. Should conditions different fro m those described in this
report be encountered during project development, GLA should be consulted to review the conditions and determine whether our recommendations are still valid. Additional exploration, testing, and analysis may be required for such
evaluation.
Should persons concerned with this project observe geotechnical features or conditions at the site or surrounding areas which are different from those described in this report, those observations should be reported immediately to GLA for evalu ation.
It is important that the information in this report be made known to the design professionals involved with the project, that our recommendations be incorporated into project drawings and documents, and that the recommendations be carried out durin g construction by the contractor
and subcontractors. It is not the responsibility of
GLA
to notify the design professionals and the
project contractors and subcontractors.
The findings, conclusions
,
and recommendations in this report are applicable onl
y to the specific
project development on this specific site. These data should not be used for other projects, sites ,
or purposes unless they are reviewed by GLA or a qualified geotechnical professional.
Report prepared by,
Geo
-
Logic Associates
Chalerm (Beeson) Liang
GE 2031
Fs/
csl
Cop
y
:
Robson Homes,
Richard Yee
FIGURES
PROJECT
PA20.1055
FIGURE
1 SITE PLAN (EXISTING DEVELOPMENT)
475 & 493 ST . JOHN STREET
PLEASANTON, CALIFORNIA
6300 San Ignacio Avenue,
Suite A
San Jose, California 95119
Phone (408) 778
-
2818
Revision:
Checked By:
Date:
Drafted By:
June
2022
CAMBRIANNA DRIVE
TAPER AVENUE
SCALE (feet)
0 20 40 60 80 100 Existing
Creek
Explanation
DH
-
4 Exploratory drill hole
CPT
-
3 Cone penetration test hole
Bulk sample
PROJECT
PA20.1055
FIGURE
2 SITE PLAN (PROPOSED DEVELOPMENT)
475 & 493 ST. JOHN STREET
PLEASANTON, CALIFORNIA
6300 San Ignacio Avenue,
Suite A
San Jose, California 95119
Phone (408) 778
-
2818
Revision:
Checked By:
Date:
Drafted By:
June
2022
CAMBRIANNA DRIVE
TAPER AVENUE
SCALE (feet)
0 20 40 60 80 100 Base:
Untitled and undated site layout drawing provided by Robson Homes on November 17, 2021.
St. John Street
DH
-
3 DH
-
1 DH
-
2 DH
-
4 CPT
-
1 CPT
-
2 CPT
-
3 B
-
1 Existing Creek
Existing
Housek
Vicinity Map (no scale)
Lot 8
Lot 14
Lot 13
Lot 12
Lot 11
Lot 10
Lot 9
Lot 4
Lot 5
Lot 6
Lot 7
Lot 3
Lot 2
Lot 1
Lot 15
PROJECT
PA20.1055
FIGURE
3 LOCATIONS OF PROJECT SITE AND
ZONE 7 MONITORING WELL 16P5
475 & 493 ST. JOHN STREET
PLEASANTON, CALIFORNIA
6300 San Ignacio Avenue,
Suite A
San Jose, California 95119
Phone (408) 778
-
2818
Compiled by:
Reviewed by:
Date:
Revision:
Approximate location
of project site
Approximate location of
Zone 7 Water Agency
monitoring well
BASE
: Map showing location of their monitoring well 16P5 provided by Zone 7 Water District, via email on December 15, 2020.
June
2022
Notes:
1. Well 16P5 was dry between 7/24/2014 and 10/5/2014.
2. Top of well at elevation 354.51 feet. Bottom of well elevation unknown.
3. Water level readings were typically taken monthly.
Drafted By: BL
DEPTH TO GROUNDWATER
FIGURE
Date: June 2022
ZONE 7 WELL 16P5
4 Checked By:
475 & 493 ST. JOHN STREET
Revision:
PROJECT
SANTA CLARA COUNTY, CALIFORNIA
PA20.1055
6300 San
Ignacio Avenue
Suite A
San Jose,
California 95119
Phone (408) 778
-
2812
0 10
20 30
40 50
60 70
80 90
100
08-Oct-76
08-Oct-77
08-Oct-78
08-Oct-79
08-Oct-80
08-Oct-81
08-Oct-82
08-Oct-83
08-Oct-84
08-Oct-85
08-Oct-86
08-Oct-87
08-Oct-88
08-Oct-89
08-Oct-90
08-Oct-91
08-Oct-92
08-Oct-93
08-Oct-94
08-Oct-95
08-Oct-96
08-Oct-97
08-Oct-98
08-Oct-99
08-Oct-00
08-Oct-01
08-Oct-02
08-Oct-03
08-Oct-04
08-Oct-05
08-Oct-06
08-Oct-07
08-Oct-08
08-Oct-09
08-Oct-10
08-Oct-11
08-Oct-12
08-Oct-13
08-Oct-14
08-Oct-15
08-Oct-16
08-Oct-17
08-Oct-18
08-Oct-19
08-Oct-20
Depth to Groundwater, feet
Date
DEPTH
TO GROUNDWATER
ZONE 7 WELL 16P5
475 & 493 ST. JOHN STREET
PLEASANTON, CALIFORNIA
well
was dry between
7/24/2014 & 10/5/2014
RECOMMENDED BUILDING SETBACK
475 & 493 ST. JOHN STREET
PLEASANTON, CALIFORNIA
6300 San Ignacio Avenue, Suite A
San Jose, California 95119
Phone (408) 778
-
2818
Compiled by:
Reviewed by:
Date:
Revision:
June
2022
5 FIGURE
PROJECT
PA20.1055
Building setback:
at least 10 ft
beyond crest of
projected 2:1
(h:v) line
Existing creek bank
Projected 2:1 (horizontal:vertical) line from
toe of existing bank
Schematic Only
–
Not to Scale
PROJECT
PA20.1055
FIGURE
6 POST
-
TENSIONED SLAB
TYPICAL SECTION
475 & 493 ST. JOHN STREET
PLEASANTON, CALIFORNIA
6300 San Ignacio Avenue,
Suite A
San Jose, California 95119
Phone (408) 778
-
2818
Compiled by:
Reviewed by:
Date:
Revision:
Exterior finish grade, slope to drain
Post
-
tensioned Slab, thickness per structural design
18 -
inch minimum
embedment below
bottom of post
-
tensioned slab
6 -
inch wide
thickened edge
Moisture
-
conditioned and compaction
slab subgrade soil per geotechnical report
Subgrade Preparation and Thickened Edge for Post
-
tensioned Slab Foundations
Post
-
tensioned slab
See detail above for
post
-
tensioned slab
subgrade preparation
Footing (if required by
structural engineer)
Perimeter thickened edge
designed to retain soil behind
Exterior finish grade,
slope to drain
18 inch minimum embedment to
bottom of thickened edge or
required footing
Foundation Embedment for Post
-
tensioned Slabs with Differential Grades
Note:
1. Refer to geotechnical report for detailed recommendations.
Schematic Only
–
Not to Scale
June
2022
APPENDIXA
KEYSTOSOILCLASSIFICATION
DRILLHOLELOGS,
AND
CONEPENETRATIONTESTPLOTS
KEY TO SOIL CLASSIFICATION - FINE GRAINED SOILS
(50% OR MORE IS SMALLER THAN NO. 200 SIEVE SIZE)
(modified from ASTM D2487 to
include fine grained soils with intermediate plasticity)
MAJOR DIVISIONS
GROUP
SYMBOLS
GROUP NAMES
SILTS AND
CLAYS
(Liquid Limit
less than 35)
Low
Plasticity
Inorganic
PI < 4 or plots
below “A” line
ML
Silt, Silt with Sand or Gravel, Sandy or Gravelly Silt, Sandy or Gravelly Silt with Sand or Gravel
Inorganic
PI > 7 or plots on
or above “A” line
CL
Lean Clay, Lean Clay with Sand or Gravel, Sandy or
Gravelly Lean Clay, Sandy or Gravelly Lean Clay with Sand or Gravel
Inorganic
PI between 4
and 7
CL-ML
Silty Clay, Silty Clay with Sand or Gravel, Sandy or Gravelly Silty Clay, Sandy or Gravelly Silty Clay with Sand or Gravel Organic
See footnote 3
OL
Organic Silt (below “A” Line) or Organic Clay (on or above “A” Line)
(1,2)
SILTS AND
CLAYS
(35
≤
Liquid
Limit < 50)
Intermediate
Plasticity
Inorganic
PI < 4 or plots
below “A” line
MI
Silt, Silt with Sand or Gravel, Sandy or Gravelly Silt, Sandy or Gravelly Silt with Sand or Gravel
Inorganic
PI > 7 or plots on
or above “A” line
CI
Clay, Clay with Sand or Gravel, Sandy or Gravelly Clay, Sandy or Gravelly Clay with Sand or Gravel
Organic
See footnote 3
OI
Organic Silt (below “A” Line) or Organic Clay (on or above “A” Line)
(1,2)
SILTS AND
CLAYS
(Liquid Limit
50 or
greater)
High
Plasticity
Inorganic
PI plots below
“A” line
MH
Elastic Silt, Elastic Silt with Sand or Gravel, Sandy or Gravelly Elastic Silt, Sandy or Gravelly Elastic Silt with Sand or Gravel
Inorganic
PI plots on or
above “A” line
CH
Fat Clay, Fat Clay with Sand or
Gravel, Sandy or Gravelly
Fat Clay, Sandy or Gravelly Fat Clay with Sand or Gravel Organic
See note 3 below
OH
Organic Silt (below “A” Line) or Organic Clay (on or above “A” Line)
(1,2)
1. If soil contains 15% to 29% plus No.
200 material, include “with sand” or “with gr
avel” to group name, whichever is predomin
ant.
2. If soil contains
≥
30% plus No. 200 material, include “sandy” or “gravelly” to group name, whichever is predominant. If soil contains ≥
15% of sand or gravel sized
material, add “with sand” or “with gravel” to group name.
3. Ratio of liquid limit of oven dried sample to
liquid limit of not dried sample is less than 0.75.
CONSISTENCY
UNCONFINED
SHEAR STRENGTH
(KSF)
STANDARD
PENETRATION
(BLOWS/FOOT)
P lasticity Chart
0 1 0
20 30
40 50
60 0 1 0 20 30 40 5 0 60 7 0 80 90 1 00 1 1 0
Plasticity Index
Liquid Lim it
"U " L ine
"A" L ine
CH or OH
MH or OH
C
I
o
r
O
I
MI
or
OI
CL
or O
L
CL -M L
M L or O
L
VERY SOFT
< 0.25
< 2
SOFT
0.25 – 0.5
2 – 4
FIRM
0.5 – 1.0
5 – 8
STIFF
1.0 – 2.0
9 – 15
VERY STIFF
2.0 – 4.0
16 – 30
HARD
> 4.0
> 30
MOISTURE
CRITERIA
Dry
Absence of moisture, dusty, dry to the
touch
Moist
Damp, but no visible water
Wet
Visible free water, usually soil is below the
water table
GEO-LOGIC ASSOCIATES
KEY TO SOIL CLASSIFICATION – COARSE GRAINED SOILS
(MORE THAN 50% IS LARGER THAN NO. 200 SIEVE SIZE)
(modified from ASTM D2487 to include fines with intermediate plasticity)
MAJOR DIVISIONS
GROUP
SYMBOLS
GROUP NAMES
1 GRAVELS
(more than
50% of
coarse
fraction is
larger than
No. 4 sieve
size)
Gravels
with less
than 5%
fines
Cu
≥
4 and
1 ≤
Cc
≤
3 GW Well Graded Gravel, Well Graded Gravel with Sand
Cu < 4 and/or
1 > Cc > 3
GP Poorly Graded Gravel, Poorly Graded Gravel with Sand Gravels
with 5% to
12% fines
ML, MI or MH
fines
GW-GM
Well Graded Gravel with Silt, Well Graded Gravel with Silt and Sand
GP-GM
Poorly Graded Gravel with Silt, P
oorly Graded Gravel with Silt
and Sand
CL, CI or CH
fines
GW-GC
Well Graded Gravel with Clay, Well Graded Gravel with Clay and Sand
GP-GC
Poorly Graded Gravel with Clay, Poorly Graded Gravel with Clay and Sand
Gravels
with more
than 12%
fines
ML, MI or MH
fines
GM Silty Gravel, Silty Gravel with Sand
CL, CI or CH
fines
GC Clayey Gravel, Claye
y Gravel with Sand
CL-ML fines GC-GM Silty Cl
ayey Gravel; Silty, Clayey Gravel with Sand
SANDS
(50% or
more of
coarse
fraction is
smaller than
No. 4 sieve
size)
Sands with
less than
5% fines
Cu
≥
6 and
1 ≤
Cc
≤
3 SW Well Graded Sand, Well Graded Sand with Gravel
Cu < 6 and/or
1 > Cc > 3
SP Poorly Graded Sand, Poorly Graded Sand with Gravel
Sands with
5% to 12%
fines
ML, MI or MH
fines
SW-SM
Well Graded Sand with Silt, Well Graded Sand with Silt and Gravel
SP-SM
Poorly Graded Sand with Silt, Poorly Graded Sand with Silt and Gravel
CL, CI or CH
fines
SW-SC
Well Graded Sand with Clay, Well Graded Sand with Clay and Gravel
SP-SC
Poorly Graded Sand with Clay, Poorly Graded Sand with Clay and Gravel
Sands with
more than
12% fines
ML, MI or MH
fines
SM Silty Sand, Silty Sand with Gravel
CL, CI or CH
fines
SC Clayey Sand, Clayey Sand with Gravel
CL-ML fines SC-SM Silty, Clayey Sand; Silty, Clayey Sand with Gravel
US STANDARD SIEVES
3 Inch ¾ Inch No. 4 No. 10 No. 40 No. 200
COARSE FINE COARSE MEDIUM FINE
COBBLES & BOULDERS GRAVELS SANDS SILTS AND CLAYS
RELATIVE DENSITY
(SANDS AND GRAVELS)
STANDARD
PENETRATION
(BLOWS/FOOT)
1. Add “with sand” to group name if material contains 15% or greater of sand-sized particle. Add “with gravel”
to group name if material contains
15% or greater of gravel-sized particle.
Very Loose 0 - 4
Loose 5 – 10
MOISTURE CRITERIA
Medium Dense 11 – 30
Dry Absence of moisture, dusty, dry to the touch
Dense 31 - 50
Moist Damp, but no visible water
Very Dense 50+
Wet Visible free water, usually soi is below the water table
GEO-LOGIC ASSOCIATES
DATE:
DH‐ 1
PROJECTNUMBER:
LOGGEDBY:
HOLEELEVATION:
D=3"OD,2½"IDSplit‐spoon
X=2½"OD,2"IDSplit‐spoon
I=StandardPenetrometer(2"ODSPT)
S=Sloughinsample
SOILTYPE
DEPTH
(ft)
SAMPLE
BLOWSPER
FOOT
POCKETPEN
(tsf)
%PASSING
#200SIEVE
LIQUID
LIMIT
WATER
CONTENT
PLASTICITY
INDEX
DRYDENSITY
(pcf)
FAILURE
STRAIN(%)
UNCONFINED
COMPRESSIVE
STRENGTH(psf)
ML S
D
D 3.25 65 22 14 2 100
S
CL D
D 1.75 23 92
S
D
D 1.0 19 106
SP
S
D
D
S
D
D 12 114
PAGE:
20 GEO‐LOGICASSOCIATES
1of1
18 dense
19 48
16 17
14 27
15 12
13 9
5 17
lightbrown
10 11
8 9
6 7
4 DESCRIPTIONOF
EARTHMATERIALS
PavementSection
(±3"ACover±4"Base)
1 2 11
‐‐‐
SAMPLER: GROUNDWATERDEPTH:
Initial:
‐‐‐
Final:
‐‐‐
3 11/13/2020
LOGOFEXPLORATORYDRILLHOLE
PROJECTNAME:
475&493St.JohnStreet,Pleasanton,CA PA20.1055
DRILLRIG:
MobileB‐61,automatichammer FS
HOLEDIAMETER:
8‐inchhollowstemauger
BOTTOMOFHOLE=20Feet
Nogroundwaterencountered
POORLYGRADEDSAND:
Brown,moist,medium
dense
SANDYSILT:
Brown,moist,verystiff;with
LEANCLAY:
Brown,moist,stiff
DATE:
DH‐ 2
PROJECTNUMBER:
LOGGEDBY:
HOLEELEVATION:
D=3"OD,2½"IDSplit‐spoon
X=2½"OD,2"IDSplit‐spoon
I=StandardPenetrometer(2"ODSPT)
S=Sloughinsample
SOILTYPE
DEPTH
(ft)
SAMPLE
BLOWSPER
FOOT
POCKETPEN
(tsf)
%PASSING
#200SIEVE
LIQUID
LIMIT
WATER
CONTENT
PLASTICITY
INDEX
DRYDENSITY
(pcf)
FAILURE
STRAIN(%)
UNCONFINED
COMPRESSIVE
STRENGTH(psf)
ML S
D
D 1.25 5
S
D
D 1.0 5 96
S
D
D 4.5+ 9 104
SM
S
D
D
SW‐
SC
S
D
D
PAGE:
20 GEO‐LOGICASSOCIATES
1of1
18 19
72 16
17 15
13 hard
14 11
12 PA20.1055
DRILLRIG:
MobileB‐61,automatichammer FS
2 HOLEDIAMETER:
8‐inchhollowstemauger ‐‐‐
SAMPLER: GROUNDWATERDEPTH:
‐‐‐
Final:
‐‐‐
DESCRIPTIONOF
EARTHMATERIALS
PavementSection
(±3"ACover±4"Base)
1 22
11/13/2020
LOGOFEXPLORATORYDRILLHOLE
PROJECTNAME:
475&493St.JohnStreet,Pleasanton,CA
Initial:
4 brown
28 5
33 10
3 70
6 9
7 8
BOTTOMOFHOLE=20Feet
Nogroundwaterencountered
SILTYSAND:
Lightbrown,moist,verydense
WELL GRADEDSANDwithGRAVELandCLAY:
Brown,moist,very dense;finetocoarsesand,
finegravel
SANDYSILT:
Lightbrown,moist,verystiff;with
DATE:
DH‐ 3
PROJECTNUMBER:
LOGGEDBY:
HOLEELEVATION:
D=3"OD,2½"IDSplit‐spoon
X=2½"OD,2"IDSplit‐spoon
I=StandardPenetrometer(2"ODSPT)
S=Sloughinsample
SOILTYPE
DEPTH
(ft)
SAMPLE
BLOWSPER
FOOT
POCKETPEN
(tsf)
%PASSING
#200SIEVE
LIQUID
LIMIT
WATER
CONTENT
PLASTICITY
INDEX
DRYDENSITY
(pcf)
FAILURE
STRAIN(%)
UNCONFINED
COMPRESSIVE
STRENGTH(psf)
ML S
D
D 4.5+ 7 123
S
D
D 1.75 8 94
SP‐
SC
S
D
D 7 2
S
D
D 4 122
S
D
D 8 5
PAGE:
20 GEO‐LOGICASSOCIATES
1of3
18 19
15 16
17 14
34 15
12 13
SW‐
SC
4 stif
f
5 11
11 8
9 10
39 11/13/2020
LOGOFEXPLORATORYDRILLHOLE
PROJECTNAME:
475&493St.JohnStreet,Pleasanton,CA
PavementSection
(±3"ACover±4"Base)
1 2 70
6 7
PA20.1055
DRILLRIG:
MobileB‐61,automatichammer FS
DESCRIPTIONOF
EARTHMATERIALS
HOLEDIAMETER:
8‐inchhollowstemauger ‐‐‐
SAMPLER: GROUNDWATERDEPTH:
Initial:
‐‐‐
Final:
48ft
3 WELLGRADEDSANDwithGRAVELandCLAY:
Brown,moist,mediumdensetodense;fineto
coarsesand,withfinegravel
POORLYGRADEDSANDwithCLAY:
Brown,
moist,dense
SANDYSILT:
Brown,moist,hard;withmostly
DATE:
DH‐ 3
PROJECTNUMBER:
LOGGEDBY:
HOLEELEVATION:
D=3"OD,2½"IDSplit‐spoon
X=2½"OD,2"IDSplit‐spoon
I=StandardPenetrometer(2"ODSPT)
S=Sloughinsample
SOILTYPE
DEPTH
(ft)
SAMPLE
BLOWSPER
FOOT
POCKETPEN
(tsf)
%PASSING
#200SIEVE
LIQUID
LIMIT
WATER
CONTENT
PLASTICITY
INDEX
DRYDENSITY
(pcf)
FAILURE
STRAIN(%)
UNCONFINED
COMPRESSIVE
STRENGTH(psf)
S
I
I
S
I
I
S
I
I 8 7
S
I
I
PAGE:
20 32
32 38
GEO‐LOGICASSOCIATES
37 38
35 2of3
39 40
33 34
31 32
36 29
dense
30 27
28 25
26 23
24 SP‐
SC
DESCRIPTIONOF
EARTHMATERIALS
21 22
HOLEDIAMETER:
8‐inchhollowstemauger
SW‐
SC
‐‐‐
SAMPLER: GROUNDWATERDEPTH:
Initial:
‐‐‐
Final:
48ft
PROJECTNAME:
475&493St.JohnStreet,Pleasanton,CA PA20.1055
DRILLRIG:
MobileB‐61,automatichammer FS
11/13/2020
LOGOFEXPLORATORYDRILLHOLE
WELLGRADEDSANDwithGRAVELandCLAY
(continued)
POORLY GRADEDSANDwithGRAVELandCLAY:
Brown,moist,mediumdense;finetocoarse
sand,finetocoarsegravel
DATE:
DH‐ 3
PROJECTNUMBER:
LOGGEDBY:
HOLEELEVATION:
D=3"OD,2½"IDSplit‐spoon
X=2½"OD,2"IDSplit‐spoon
I=StandardPenetrometer(2"ODSPT)
S=Sloughinsample
SOILTYPE
DEPTH
(ft)
SAMPLE
BLOWSPER
FOOT
POCKETPEN
(tsf)
%PASSING
#200SIEVE
LIQUID
LIMIT
WATER
CONTENT
PLASTICITY
INDEX
DRYDENSITY
(pcf)
FAILURE
STRAIN(%)
UNCONFINED
COMPRESSIVE
STRENGTH(psf)
S
I
I
SW‐
SC S
I
I 8 8
PAGE:
55 56
39 40
SP‐
SC
GROUNDWATERDEPTH:
GEO‐LOGICASSOCIATES
3of3
59 60
57 58
53 54
51 52
50 47
48 49
45 46
43 44
densetoverydense
DESCRIPTIONOF
EARTHMATERIALS
41 42
SAMPLER:
Initial:
‐‐‐
Final:
48ft
DRILLRIG:
MobileB‐61,automatichammer FS
HOLEDIAMETER:
8‐inchhollowstemauger ‐‐‐
11/13/2020
LOGOFEXPLORATORYDRILLHOLE
PROJECTNAME:
475&493St.JohnStreet,Pleasanton,CA PA20.1055
BOTTOMOFHOLE=50Feet
WELLGRADEDGRAVELwithSANDandCLAY:
Brown,moist,densetoverydense;fineto
POORLYGRADEDSANDwith GRAVELand
DATE:
DH‐ 4
PROJECTNUMBER:
LOGGEDBY:
HOLEELEVATION:
D=3"OD,2½"IDSplit‐spoon
X=2½"OD,2"IDSplit‐spoon
I=StandardPenetrometer(2"ODSPT)
S=Sloughinsample
SOILTYPE
DEPTH
(ft)
SAMPLE
BLOWSPER
FOOT
POCKETPEN
(tsf)
%PASSING
#200SIEVE
LIQUID
LIMIT
WATER
CONTENT
PLASTICITY
INDEX
DRYDENSITY
(pcf)
FAILURE
STRAIN(%)
UNCONFINED
COMPRESSIVE
STRENGTH(psf)
ML S
D
D 24 7 3 94
S
D
D 1.5 8 95
SW‐
SC
S
D
D 15
S
D
D
S
D
D
PAGE:
20 GEO‐LOGICASSOCIATES
1of1
18 19
56 16
17 14
53 15
12 13
22 verystif
f
5 57
10 11
8 9
6 7
3 4
DESCRIPTIONOF
EARTHMATERIALS
PavementSection
(±3"ACover±4"Base)
1 2 52
‐‐‐
SAMPLER: GROUNDWATERDEPTH:
Initial:
‐‐‐
Final:
‐‐‐
11/13/2020
LOGOFEXPLORATORYDRILLHOLE
PROJECTNAME:
475&493St.JohnStreet,Pleasanton,CA PA20.1055
DRILLRIG:
MobileB‐61,automatichammer FS
HOLEDIAMETER:
8‐inchhollowstemauger
BOTTOMOFHOLE=20Feet
Nogroundwaterencountered
WELL GRADEDSANDwithGRAVELandCLAY:
Brown,moist,densetoverydense;fineto
coarsesand
SANDYSILT:
Brown,moist,verystifftohard;
Geo-Logic Associates
Project
475 & 493 St John St
Operator
BH-ZG
Filename
SDF(380).cpt
Job Number
PA20.1055.00
Cone Number
DDG1496
GPS
Hole Number
CPT-01
Date and Time
11/13/2020 8:24:54 AM
Maximum Depth
51.02 ft
EST GW Depth During Test
48.00 ft
Net Area Ratio .8
Cone Size 15cm squared
Soil Behavior Referance
*Soil behavior type and SPT based on data from UBC-1983 0 5
10 15
20 25
30 35
40 45
50 0
700
TIP
TSF
0 7
FRICTION
TSF
0 5
Fs/Qt
%
0 120
SPT N
0 12
1 - sensitive fine grained
2 - organic material
3 - clay
4 - silty clay to clay
5 - clayey silt to silty clay
6 - sandy silt to clayey silt
7 - silty sand to sandy silt
8 - sand to silty sand
9 - sand
10 - gravelly sand to sand
11 - very stiff fine grained (*)
12 - sand to clayey sand (*)
CPT DATA
DEPTH
(ft)
SOIL
BEHAVIOR
TYPE
Geo-Logic Associates
Project
475 & 493 St John St
Operator
BH-ZG
Filename
SDF(382).cpt
Job Number
PA20.1055.00
Cone Number
DDG1496
GPS
Hole Number
CPT-02
Date and Time
11/13/2020 10:46:17 AM
Maximum Depth
30.68 ft
EST GW Depth During Test
48.00 ft
Net Area Ratio .8
Cone Size 15cm squared
Soil Behavior Referance
*Soil behavior type and SPT based on data from UBC-1983 0 5
10 15
20 25
30 35
40 45
50 0
700
TIP
TSF
0 7
FRICTION
TSF
0 5
Fs/Qt
%
0 120
SPT N
0 12
1 - sensitive fine grained
2 - organic material
3 - clay
4 - silty clay to clay
5 - clayey silt to silty clay
6 - sandy silt to clayey silt
7 - silty sand to sandy silt
8 - sand to silty sand
9 - sand
10 - gravelly sand to sand
11 - very stiff fine grained (*)
12 - sand to clayey sand (*)
CPT DATA
DEPTH
(ft)
SOIL
BEHAVIOR
TYPE
Geo-Logic Associates
Project
475 & 493 St John St
Operator
BH-ZG
Filename
SDF(381).cpt
Job Number
PA20.1055.00
Cone Number
DDG1496
GPS
Hole Number
CPT-03
Date and Time
11/13/2020 9:55:23 AM
Maximum Depth
51.02 ft
EST GW Depth During Test
48.00 ft
Net Area Ratio .8
Cone Size 15cm squared
Soil Behavior Referance
*Soil behavior type and SPT based on data from UBC-1983 0 5
10 15
20 25
30 35
40 45
50 0
700
TIP
TSF
0 7
FRICTION
TSF
0 5
Fs/Qt
%
0 120
SPT N
0 12
1 - sensitive fine grained
2 - organic material
3 - clay
4 - silty clay to clay
5 - clayey silt to silty clay
6 - sandy silt to clayey silt
7 - silty sand to sandy silt
8 - sand to silty sand
9 - sand
10 - gravelly sand to sand
11 - very stiff fine grained (*)
12 - sand to clayey sand (*)
CPT DATA
DEPTH
(ft)
SOIL
BEHAVIOR
TYPE
APPENDIXB
LABORATORYTESTRESULTS
ATTERBERG LIMITS
Summary Report
ASTM D-4318
Client :
Project No:
Lab Log No.:
Robson Homes LLC
Project Name:
Report Date:
475 & 493 St. St. John Street
LIQUID PLASTIC PLASTIC
LSN
LIMIT LIMIT INDEX
4699A
o
o o
o
DH-1 @ 2-2.5
22 20 2
4699B
DH-4 @ 2-2.5
24 21 3
This testing is based upon accepted industry practi
ce as well as the test method listed. These result
s apply only to the samples
supplied and tested for the above referenced job.
L : Labexcel \ Projects \ Client \ Robson Homes LL
\ PA20.1055.00 \ 4699-PI-Base.xls
Print Date:
Entered By:
Reviewed By:
LLN:
DCN: PI-rp (rev. 9/18/12)
RZS PP
DESCRIPTION
brown sandy silt (ML)
brown sandy silt
4699
November 24, 2020
4699
SAMPLE
IDENTIFICATION
PA20.1055.00
SAMPLE
11/29/20
SYMBOL
0 10
20 30
40 50
0 10 20 30 40 50 60 70 80 90 100 110
PLASTIC INDEX (PI)
LIQUID LIMIT (LL)
PLASTICITY CHART
CL - ML
ML or OL
MH or OH
CL or OL
CH or OH
U - Line
A - Line
PARTICLE SIZE ANALYSIS
Test Report
ASTM D-6913 / D-7928, (replacing D-422)
Method B:(+/-0.1%)
Client :
Project No:
Lab Sample No:
ROBSON HOMES LLC
PA20.1055.00
4699A
Project Name:
Report Date:
475 & 493 ST. JOHN STREET
COARSE
Description
Size Passing, mm
D
60 =
D
10 =
5 micron (%) =
16 Coefficient of Curvature, C
c
: Coefficient of Uniformity, C
u
:
37.19 Fineness Modulus = 0.12
Note: * Percentages are +/- 0.1% based on computer
rounding as allowed by ASTM D-6026-01 Section 5.2.3
.
This testing is based upon accepted industry practi
ce as well as the test method listed. These result
s apply only to the samples
supplied and tested for the above referenced job.
L : Labexcel \ Projects \ Client \ Client Name \ 46
99 \ 4699A-ma
Print Date:
Entered By:
Reviewed By:
LSN:
DCN: MA-rp (rev. 6/27/12)
RZS PP
4699A
0.07 Symbol
DH-1 @ 2-2.5 brown sandy silt (ML)
4.08 0.02
D
30 =
Sample ID
US STANDARD SIEVE SIZE No.
FINE
US SIEVE SIZE, INCHES
FINE
BOULDERS COBBLES
November 24, 2020
GRAVEL
MEDIUM
SAND
COARSE
SILT AND CLAY
11/29/20
HYDROMETER
% Sand
% Gravel
0.00 0.0 35.1 64.9
% Silt - Clay
6" 3" 1.5" 3/4" 3/8" 4 10 20 30 40 50 100 200
0 10
20 30
40 50
60 70
80 90
100
0 10
20 30
40 50
60 70
80 90
100
0.00 0.01
0.10 1.00
10.00 100.00
1000.00
Percent Retained
Percent Passing
Particle Diameter, mm
'R' VALUE
CA 301
Project 475 & 493 St. John St. Date: 11/22/20 By: LD
Job #: PA20.1055 Sample : Bulk
Soil Type: Brown, Sandy Silt w. Gravel
TEST SPECIMEN A B C D
Compactor Air Pressure psi
70 250 300
Initial Moisture Content %
4.2 4.2 4.2
Water Added ml
80 60 40
Moisture at Compaction % 11.1 9.4 7.7
Sample & Mold Weight gms
3215 3238 3232
Mold Weight gms
2095 2097 2098
Net Sample Weight gms 1120 1141 1134
Sample Height in.
2.459 2.472 2.461
Dry Density pcf 124.2 127.8 129.7
Pressure lbs
2075 4965 7830
Exudation Pressure psi 165 395 623
Expansion Dial x 0.0001
2 47 70
Expansion Pressure psf 9 204 303
Ph at 1000lbs psi
60 35 23
Ph at 2000lbs psi
123 59 40
Displacement turns
4.83 4.13 3.79
R' Value
13 51 66
Corrected 'R' Value
13 51 66
FINAL 'R' VALUE
By Exudation Pressure (@ 300 psi):
38 By Epansion Pressure :
32 TI =
5
APPENDIXC
RESULTSOFLIQUEFACTIONANALYSES
L I Q U E F A C T I O N A N A L Y S I S R E P O R T
Input parameters and analysis data
Robertson (2009)
Robertson (2009)
Based on Ic value
7.50 0.85
.
G.W.T. (in-situ):
G.W.T. (earthq.):
Average results interval:
Ic cut-off value:
Unit weight calculation:
Project title : 475 & 493 St. John Street
Location : Pleasanton, CA
GeoLogismiki
Geotechnical Engineers
Merarhias 56
http://www.geologismiki.gr
CPT file : CPT-01
48.00 ft
25.00 ft
3 2.60
Based on SBT
No
N/A
N/A
Yes
Yes
Clay like behavior
applied:
Limit depth applied:
Limit depth:
MSF method:
All soils
No
N/A
Method based
Summary of liquefaction potential
CLiq v.2.1.6.7 - CPT Liquefaction Assessment Software - Report created on: 12/15/2020, 3:55:20 PM Project file: E:\1A_Beeson\1_Active Projects\PA20.1055.00 475 & 493 St John Street\Engineering\CLiq\[email protected] 1
This software is licensed to: Geo-Logic Associates
CPT name: CPT-01
C P T b a s i c i n t e r p r e t a t i o n p l o t s ( n o r m a l i z e d ) CLiq v.2.1.6.7 - CPT Liquefaction Assessment Software - Report created on: 12/15/2020, 3:55:20 PM 3 Project file: E:\1A_Beeson\1_Active Projects\PA20.1055.00 475 & 493 St John Street\Engineering\CLiq\[email protected] SBTn legend
1. Sensitive fine grained
2. Organic material
3. Clay to silty clay
4. Clayey silt to silty
clay
5. Silty sand to sandy silt
6. Clean sand to silty sand
7. Gravely sand to sand
8. Very stiff sand to
clayey sand
9. Very stiff fine grained
Input parameters and analysis data
Robertson (2009)
Robertson (2009)
Based on Ic value
7.50 0.85
48.00 ft
Depth to water table (erthq.):
Average results interval:
Ic cut-off value:
Unit weight calculation:
Use fill:
Fill height:
25.00 ft
3 2.60
Based on SBT
No
N/A
N/A
Yes
Yes
All soils
No
N/A
This software is licensed to: Geo-Logic Associates
CPT name: CPT-01
L i q u e f a c t i o n a n a l y s i s o v e r a l l p l o t s CLiq v.2.1.6.7 - CPT Liquefaction Assessment Software - Report created on: 12/15/2020, 3:55:20 PM 5 Project file: E:\1A_Beeson\1_Active Projects\PA20.1055.00 475 & 493 St John Street\Engineering\CLiq\[email protected] F.S. color scheme
LPI color scheme
Input parameters and analysis data
Robertson (2009)
Robertson (2009)
Based on Ic value
7.50 0.85
48.00 ft
Depth to water table (erthq.):
Average results interval:
Ic cut-off value:
Unit weight calculation:
Use fill:
Fill height:
25.00 ft
3 2.60
Based on SBT
No
N/A
N/A
Yes
Yes
All soils
No
N/A
Almost certain it will liquefy
Very likely to liquefy
Liquefaction and no liq. are equally likely
Unlike to liquefy
Almost certain it will not liquefy
Very high risk
High risk
Low risk
L I Q U E F A C T I O N A N A L Y S I S R E P O R T
Input parameters and analysis data
Robertson (2009)
Robertson (2009)
Based on Ic value
7.50 0.85
.
G.W.T. (in-situ):
G.W.T. (earthq.):
Average results interval:
Ic cut-off value:
Unit weight calculation:
Project title : 475 & 493 St. John Street
Location : Pleasanton, CA
GeoLogismiki
Geotechnical Engineers
Merarhias 56
http://www.geologismiki.gr
CPT file : CPT-03
48.00 ft
25.00 ft
3 2.60
Based on SBT
No
N/A
N/A
Yes
Yes
Clay like behavior
applied:
Limit depth applied:
Limit depth:
MSF method:
All soils
No
N/A
Method based
Summary of liquefaction potential
CLiq v.2.1.6.7 - CPT Liquefaction Assessment Software - Report created on: 12/15/2020, 3:56:35 PM Project file: E:\1A_Beeson\1_Active Projects\PA20.1055.00 475 & 493 St John Street\Engineering\CLiq\[email protected] 1
This software is licensed to: Geo-Logic Associates
CPT name: CPT-03
C P T b a s i c i n t e r p r e t a t i o n p l o t s ( n o r m a l i z e d ) CLiq v.2.1.6.7 - CPT Liquefaction Assessment Software - Report created on: 12/15/2020, 3:56:35 PM 3 Project file: E:\1A_Beeson\1_Active Projects\PA20.1055.00 475 & 493 St John Street\Engineering\CLiq\[email protected] SBTn legend
1. Sensitive fine grained
2. Organic material
3. Clay to silty clay
4. Clayey silt to silty
clay
5. Silty sand to sandy silt
6. Clean sand to silty sand
7. Gravely sand to sand
8. Very stiff sand to
clayey sand
9. Very stiff fine grained
Input parameters and analysis data
Robertson (2009)
Robertson (2009)
Based on Ic value
7.50 0.85
48.00 ft
Depth to water table (erthq.):
Average results interval:
Ic cut-off value:
Unit weight calculation:
Use fill:
Fill height:
25.00 ft
3 2.60
Based on SBT
No
N/A
N/A
Yes
Yes
All soils
No
N/A
This software is licensed to: Geo-Logic Associates
CPT name: CPT-03
L i q u e f a c t i o n a n a l y s i s o v e r a l l p l o t s CLiq v.2.1.6.7 - CPT Liquefaction Assessment Software - Report created on: 12/15/2020, 3:56:35 PM 5 Project file: E:\1A_Beeson\1_Active Projects\PA20.1055.00 475 & 493 St John Street\Engineering\CLiq\[email protected] F.S. color scheme
LPI color scheme
Input parameters and analysis data
Robertson (2009)
Robertson (2009)
Based on Ic value
7.50 0.85
48.00 ft
Depth to water table (erthq.):
Average results interval:
Ic cut-off value:
Unit weight calculation:
Use fill:
Fill height:
25.00 ft
3 2.60
Based on SBT
No
N/A
N/A
Yes
Yes
All soils
No
N/A
Almost certain it will liquefy
Very likely to liquefy
Liquefaction and no liq. are equally likely
Unlike to liquefy
Almost certain it will not liquefy
Very high risk
High risk
Low risk
APPENDIXD
RESULTSOFSLOPESTABILITYANALYSES
1.3 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 300
310
320
330
340
350
360
HorzSeismicCoef.:0
Color Name
Model Unit
Weight
(pcf)
Cohesion'
(psf)
Phi'(°)
SandandGravel Mohr-Coulomb 126 0
36 SandySilt Mohr-Coulomb 126 100 25
GroundwaterDepth=25feet
12/16/2020
StJohnSt_StabilitySection04.gsz
Section1.5:1_Static
1:150
1.5 1
1.2 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 300
310
320
330
340
350
360
HorzSeismicCoef.:0
Color Name SlopeStabilityMaterialModel Unit
Weight
(pcf)
Effective
Cohesion
(psf)
Effective
Friction
Angle(°)
SandandGravel Mohr-Coulomb 126 0 36
SandySilt Mohr-Coulomb 126 100 25
GroundwaterDe
p
th=el342feet
03/22/2022
StJohnSt_StabilitySection05c.gsz
Section1.5:1_Static
1:150
1.5 1
1.04 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 300
310
320
330
340
350
360
HorzSeismicCoef.:0.25
Color Name
Model Unit
Weight
(pcf)
Cohesion'
(psf)
Phi'
(°)
SandandGravel(25'-35') Mohr-Coulomb 126 1,500 0
SandandGravel(35'-47') Mohr-Coulomb 126 2,400 0
SandandGravel(47'-50') Mohr-Coulomb 126 800 0
SandandGravel(6'-25') Mohr-Coulomb 126 0
36 SandySilt
Mohr-Coulomb 126 2,000 0
GroundwaterDepth=25feet
12/16/2020
StJohnSt_StabilitySection06.gsz
Section1.5:1_Seismic
1:150
1.5 1
1.7 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 300
310
320
330
340
350
360
HorzSeismicCoef.:0
Color Name
Model Unit
Weight
(pcf)
Cohesion'
(psf)
Phi'(°)
SandandGravel Mohr-Coulomb 126 0
36 SandySilt Mohr-Coulomb 126 100 25
GroundwaterDepth=25feet
12/16/2020
StJohnSt_StabilitySection07b.gsz
Section2:1_Static
1:150
2 1
1.5 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 300
310
320
330
340
350
360
HorzSeismicCoef.:0
Color Name SlopeStabilityMaterialModel Unit
Weight
(pcf)
Effective
Cohesion
(psf)
Effective
Friction
Angle(°)
SandandGravel Mohr-Coulomb 126 0 36
SandySilt Mohr-Coulomb 126 100 25
GroundwaterDe
p
th=el342feet
03/22/2022
StJohnSt_StabilitySection08c.gsz
Section2:1_Static
1:150
2 1
1.09 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 300
310
320
330
340
350
360
HorzSeismicCoef.:0.25
Color Name
Model Unit
Weight
(pcf)
Cohesion'
(psf)
Phi'
(°)
SandandGravel(25'-35') Mohr-Coulomb 126 1,500 0
SandandGravel(35'-47') Mohr-Coulomb 126 2,400 0
SandandGravel(47'-50') Mohr-Coulomb 126 800 0
SandandGravel(6'-25') Mohr-Coulomb 126 0
36 SandySilt
Mohr-Coulomb 126 2,000 0
GroundwaterDepth=25feet
12/16/2020
StJohnSt_StabilitySection09.gsz
Section2:1_Seismic
1:150
2 1
Appendix E
Phase I Environmental Site Assessment and Subsurface Investigation
D R A F T
PHASE I ENVIRONMENTAL SITE
ASSESSMENT AND SUBSURFACE
INVESTIGATION
475 AND 493 SAINT JOHN STREET
PLEASANTON, CALIFORNIA
Prepared for:
Robson Homes, LLC
San Jose, CA
Prepared By:
Ramboll US Consulting, Inc.
Emeryville, CA
Date
November 6, 2020
Project Number
1690019049
Phase I Environmental Site Assessment D R A F T
and Subsurface Investigation
Environmental Professional Statement Ramboll
SIGNATURE AND ENVIRONMENTAL PROFESSIONAL STATEMENT
I declare that, to the best of my professional knowledge and belief, I meet the definition of Environmental Professional as defined in §312.10 of 40 CFR 312.
I have the specific qualifications based on education, training, and experience to assess a property of the nature, history and setting of the subject property. I have developed and performed all appropriate inquiries in conformance with the standards and practices set forth in 40 CFR Part 312.
D R A F T
___________________________________
Anne Gates, P.E.
Senior Managing Consultant
Ramboll US Consulting, Inc.
2200 Powell Street, Suite 700
Emeryville, CA
Phase I Environmental Site Assessment D R A F T
and Subsurface Investigation
Contents i Ramboll
CONTENTS
1. SUMMARY OF CONCLUSIONS 1
1.1 Site Summary 1
1.2 Recognized Environmental Conditions 1
1.3 Other Findings 1
2. INTRODUCTION 3
2.1 Purpose 3
2.2 Scope of the Assessment 3
2.3 Significant Assumptions 4
2.4 Reliance and General Limitations 4
3. SITE DESCRIPTION 6
3.1 Site Setting 6
3.2 Current Use of the Site 8
3.3 Current Uses of Adjoining Properties 9
4. REVIEW OF PUBLIC RECORDS AND OTHER INFORMATION SOURCES 10
4.1 Environmental Regulatory Database Review 10
4.2 Historical Uses of the Site and Adjacent Sites 13
4.3 Review of Local and State Agency Information 16
4.4 Previous Environmental Assessments and Activities 16
4.5 Environmental Lien Record Search 16
4.6 User-Provided Information 16
5. SITE RECONNAISSANCE 17
5.1 Methodology and Limiting Conditions 17
5.2 General Site Setting and Observations 17
6. SOIL AND SOIL VAPOR SAMPLING 20
6.1 Pre-Field Activities 20
6.2 Soil Sampling and Soil Vapor Well Installation 20
6.3 Soil Vapor Sampling 22
6.4 Additional Shallow Soil Sampling 22
6.5 Hazardous Waste Characterization Analysis 24
7. FINDINGS, OPINION, AND CONCLUSIONS 25
7.1 Findings, Opinions, and Conclusions 25
7.2 Analysis of Data Gaps 26
8. REFERENCES 27
8.1 Documents 27
8.2 Interviews 27
9. ASTM DEFINITIONS 28
Phase I Environmental Site Assessment D R A F T
and Subsurface Investigation
Contents ii Ramboll
TABLES
Table 1: Metals in Soil Samples
Table 2: Detected Organochlorine Pesticides and Polychlorinated Biphenyls in Soil Samples Table 3: Total Petroleum Hydrocarbons and Volatile Organic Compounds in Soil Samples Table 4: Naturally-Occurring Asbestos in Soil Samples
Table 5: VOCs in Soil Vapor Samples
FIGURES
Figure 1: Site Vicinity Map
Figure 2: Site Layout
Figure 3: Sample Location Map
Figure 4: Shallow Soil Samples with Lead Exceedances
APPENDICES
Appendix A: Site Photographs
Appendix B: Environmental Database Report
Appendix C: Historical Research Documentation
C.1: Topographic Maps
C.2: Aerial Photographs
C.3: Abstract of City Directories
C.4: Historical Fire Insurance Maps
Appendix D: Site-Owner Provided Figure
Appendix E: Environmental Lien and AUL Search
Appendix F: Laboratory Analytical Reports
Appendix G: Qualifications of Environmental Professionals
Phase I Environmental Site Assessment D R A F T
and Subsurface Investigation
Summary of Conclusions 1 Ramboll
1. SUMMARY OF CONCLUSIONS
Ramboll US Corporation (“Ramboll”; formerly Ramboll Environ US Corporation) was retained by Robson Homes, LLC (“Robson Homes”) to perform a Phase I Environmental Site Assessment (ESA) and Phase II subsurface investigation at 475 and 493 Saint John Street in Pleasanton, California (herein referred to as the “site”; see Figure 1). Ramboll’s assessment was conducted in connection with the due diligence and potential purchase of the property. The objective of the Phase I ESA, which was conducted in conformance with the scope and limitations of ASTM International’s Standard Practice for Environmental Site Assessments: Phase I Environmental Site Assessment Process E1527- 13 (the “ASTM Standard”), was to identify Recognized Environmental Conditions (RECs), as defined in the ASTM Standard (see Section 2.1).
1.1 Site Summary
The approximately 2.29-acre site is located on Saint John Street in Pleasanton, California (Figure 2).
The site is owned by Joseph and Maricela Barone and is comprised of two adjoining parcels, assessor parcel numbers (APNs) 94-114-7 (475 Saint John Street) and 94-114-8 (493 Saint John Street). The parcel located at 475 Saint John Street (“Eastern Parcel”) is improved with Barone’s Italian restaurant, which includes a covered dining patio, adjoining portable restrooms, multiple small storage structures along the perimeter of the parcel, and an outdoor dining/event space. The parcel located at 493 Saint John Street (“Western Parcel”) is improved with a single-family residence, an accessory dwelling unit, one detached garage structure, two detached permanent structures (used for general storage and an exercise room), two shipping containers for restaurant storage, and an asphalt paved parking lot utilized for restaurant parking located north of the residence. A paved road trends northeast- southwest down the center of the site for access to the parking lot.
The site was improved with two single-family residential structures as early as the 1880s. By the 1970s, the residence at 475 Saint John Street was converted to a restaurant. After the Barone family purchased the site in 1995, improvements were made to the restaurant and residence. Following the improvements, the site generally appeared as it does today.
1.2 Recognized Environmental Conditions
Ramboll performed a Phase I ESA of the site in conformance with the scope and limitations of the ASTM Standard and a Phase II subsurface investigation of the site. Any exceptions to, or deletions from, this practice are described in Section 7.2 of this report. This assessment has revealed the following REC in connection with unrestricted residential use of the site:
• Areas of Elevated Lead in Shallow Soil. Results from soil sampling conducted by Ramboll in September and October 2020 identified concentrations of lead in shallow soil above regulatory screening criterion for residential land use, as discussed in Section 6 of this report. The shallow soil with elevated lead appears to be located in the vicinity of current and former structures at the site. The vertical extent of the elevated lead appears to be limited to the upper 2 feet. The horizonal extent could not be fully delineated due to the presence of on-site structures.
1.3 Other Findings
Although not a considered REC based on currently available information, Ramboll identified the following other findings. The term “other finding” is not defined by ASTM; rather, Ramboll uses the term to connote areas of contingent risk that are not clearly defined by the ASTM Standard.
Phase I Environmental Site Assessment D R A F T
and Subsurface Investigation
Summary of Conclusions 2 Ramboll
• Potential Former Underground Storage Tank (UST). The EDR report identified a former 1,000-gallon unleaded gasoline UST at the site on the Statewide Environmental Evaluation and Planning System Underground Storage Tank (SWEEPS UST) database. The current site owner was unaware of current or former USTs at the site. The former site owner reportedly recalls her husband removing the UST from the southwest corner of the parking lot in the early 1990s and provided a hand-drawn sketch of the possible location (see Appendix D). Ramboll contacted the City of Pleasanton Fire Department (Fire Department), the Alameda County Department of Environmental Health (ACDEH), and the San Francisco Regional Water Quality Control Board (SFRWQCB), but none of the agencies reported having records of the UST.
Ramboll advanced two borings to 10 feet below ground surface (bgs) in the vicinity of the potential former UST. No soil staining, odors, or other evidence of the potential fuel UST were observed by Ramboll field personnel. Soil sampling conducted in the vicinity of the potential former UST location also did not detect fuel constituents. Soil vapor sampling detected benzene slightly above the residential regulatory screening criteria at one of the two locations in the vicinity of the potential former UST (SV04); however, SV04 is in the parking lot and concentrations of benzene are commonly detected at these concentrations in vehicle use areas. No additional fuel constituents or by-products were detected in soil vapor samples above regulatory screening criteria for unrestricted residential land use. No further investigation is recommended at this time.
• Nearby Dry-Cleaning Sites. Several dry-cleaning facilities are located in relatively close proximity to the site as discussed in more detail in Section 4.1.3. Several of these facilities have identified chlorinated solvents in soil vapor and/or groundwater above regulatory screening criteria. These off-site properties potentially pose a contamination concern to the subject site. To address the potential contamination concern, soil vapor sampling was performed at the site, as discussed in Section 6.3. Based on the results of the soil vapor sampling conducted by Ramboll at the site, these dry-cleaning properties are not considered of concern for the site.
De minimis conditions identified during this review are discussed in Section 7.1.
Phase I Environmental Site Assessment D R A F T
and Subsurface Investigation
Introduction 3 Ramboll
2. INTRODUCTION
2.1 Purpose
Ramboll was retained by Robson Homes to conduct a Phase I ESA and subsurface soil and soil vapor investigation of the approximately 2.3-acre site at 475 and 493 Saint John Street in Pleasanton, California (APNs 94-114-7 and 94-114-8, respectively). Ramboll’s assessment was conducted in connection with the due diligence and potential purchase of the property. The purpose of the assessment was to identify RECs, which are defined in the ASTM Standard as:
“The presence or likely presence of any hazardous substances or petroleum products in, on, or at a property: (1) due to release to the environment; (2) under conditions indicative of a release to the environment; or (3) under conditions that pose a material threat of a future release to the environment. De minimis conditions are not recognized environmental conditions.”
2.2 Scope of the Assessment
Ramboll completed the following tasks, consistent with the ASTM Standard, during its Phase I ESA of the property:
• A visit to the site by Michael Gaffney of Ramboll on September 1, 2020 to observe the exterior and interior features of the site and to identify the uses and conditions specified in the ASTM Standard.
In addition, Ramboll observed the adjoining properties from the site or adjacent public thoroughfares. Photographs taken during the site visit are included in Appendix A. • An interview was conducted during the September 1, 2020 site visit with Mr. Joe Barone, site owner. Mr. Barone has resided at the site and operated the restaurant since purchasing the site in 1995. The aforementioned individual is referred to herein as “site owner”. The site owner interviewed by Ramboll was identified as having good knowledge of the uses and physical characteristics of the site. The site owner contacted the previous site owner for additional information in regard to the potential former UST at the site. The aforementioned individual is referred to herein as “former site owner”. Ramboll did not contact the former site owner. • Visits to the site by Ramboll in September and October 2020 to collect soil and soil vapor samples. • A review of information contained in federal and state environmental databases, as obtained from the sources noted below:
- A radius report prepared by EDR, Inc. (EDR, see Appendix B) in September 2020 presents the results of searches of federal and state databases for the subject site, as well as properties near the subject site. The radius searched for each database, as well as the databases themselves, were selected in accordance with the ASTM Standard. - The United States Environmental Protection Agency’s (USEPA’s) Envirofacts database, which provides site information contained in multiple USEPA regulatory databases. - The USEPA’s Enforcement and Compliance History Online (ECHO) database, which provides information on sites’ enforcement and compliance history. - The State of California’s RWQCB GeoTracker online database and the California Environmental Protection Agency (Cal/EPA) Department of Toxic Substances Control (DTSC) Envirostor online database.
Phase I Environmental Site Assessment D R A F T
and Subsurface Investigation
Introduction 4 Ramboll
- The California Department of Conservation, Geologic Energy Management Division’s (CalGEM) Well Finder, which contains information regarding the geographic distribution of oil and gas wells.
• A review of standard historical sources (included as Appendix C) and local agency inquiries, as defined in the ASTM Standard. The following resources were reviewed:
- Readily available historical sources, including (where available) historical topographic maps and aerial photographs, city directories, and Sanborn Maps, to develop a history of the previous uses of the site and surrounding area.
- Historical and site-specific information obtained from the following local agencies: City of Pleasanton Community Development Department (Building Department) and the Alameda County Assessor’s Office (Assessor’s Office). The Fire Department identified that they have general inspection documentation related to the Eastern Parcel, but the Fire Department had not provided Ramboll with the inspection reports at the time this report was completed. The ACDEH and the SFRWQCB did not have documents pertaining to the site. • A review of physical setting sources, as defined in the ASTM Standard, including:
- The current United States Geological Survey (USGS) 7.5-minute topographic map that shows the area on which the site is located.
- Geologic, hydrogeologic, or hydrologic sources as provided in the EDR report. • A search for environmental liens or other activity and use limitations (AULs) for the site, provided by EDR (as shown in Appendix E). Ramboll ordered the lien search using parcel numbers 94-114- 7 and 94-114-8 as obtained from the local tax assessor’s office and other online resources. • A review of any information provided by the user of this assessment, including information consistent with Appendix X3 of the ASTM Standard. Pertinent information, if any, is discussed in the appropriate sections of this report.
This assessment was conducted in accordance with the methodology specified in ASTM Standard E1527-13, as agreed upon by Ramboll and Robson Homes in September 2020.
2.3 Significant Assumptions
In conducting this review, no significant assumptions were made, except for the following:
• Site-specific field measurements or other detailed hydrogeological information was not publicly available or reasonably ascertainable. In the absence of such data, Ramboll has assumed that the flow direction of shallow groundwater beneath the site and in the local vicinity generally mimics surface topography. Therefore, in evaluating potential on-site impacts from off-site sources, those off-site facilities not located adjacent to or within one-quarter mile upgradient of the subject site are not considered to represent a significant concern to the subject site. This interpretation is based on the assumption that a hazardous material released to the subsurface generally does not migrate laterally within the unsaturated soil for a significant distance, while a hazardous material may migrate in groundwater in a generally downgradient direction.
2.4 Reliance and General Limitations
This report has been prepared for the exclusive use of Robson Homes, LLC and affiliated entities including Santa Clara Development Company, Sun Lakes Construction Company of California, and
Phase I Environmental Site Assessment D R A F T
and Subsurface Investigation
Introduction 5 Ramboll
Vesta Real Estate Company Inc., and such other persons or entities whose reliance is explicitly authorized in writing by Ramboll.
Under the ASTM Standard, this report is considered current only until April 7, 2021 (a period of 180 days from the date of the most recent site visit on October 9, 2020). The conclusions presented in this report represent Ramboll’s best professional judgment based upon the information available and conditions existing as of the date of this report. In performing its assignment, Ramboll must rely upon publicly available information, information provided by the client, and information provided by third parties. Accordingly, the conclusions in this report are valid only to the extent that the information provided to Ramboll was accurate and complete. This review is not intended as legal advice, nor is it an exhaustive review of site conditions or facility compliance.
The scope of work for this assessment did not include an asbestos survey or inspection of existing buildings. Other issues considered outside the scope of the ASTM Standard and this review include radon, lead in drinking water, wetlands, cultural and historic resources, ecological resources, endangered species, and high voltage power lines.
Phase I Environmental Site Assessment D R A F T
and Subsurface Investigation
Site Description 6 Ramboll
3. SITE DESCRIPTION
3.1 Site Setting
The site is located on Saint John Street in Pleasanton, Alameda County, California. According to the Assessor’s Office, the APNs for the site are 94-114-7 (475 Saint John Street, the “Eastern Parcel”) and 94-114-8 (493 Saint John Street, the “Western Parcel”). The site is approximately 2.3-acres in area and is located in downtown Pleasanton (Figure 1). The Eastern Parcel is improved with Barone’s, an Italian restaurant. The restaurant is located on the southern portion of the parcel with a concrete patio for outdoor dining/event space on the northern portion of the parcel. The Western Parcel is improved with a two-story residence with a basement, a one-story accessory dwelling unit, three small accessory garages/storage structures, and two shipping containers used for storage. The northern portion of Western Parcel is an asphalt paved parking area for Barone’s restaurant. The site was historically used for single-family residential homes.
The site is accessed from Saint John Street at the southern site boundary. A paved road trends northeast-southwest in the center of the site from the southern site boundary to the northern parking lot. An intermittent steam, Arroyo Valle, intersects the northern site boundary. There are no other on-site surface water bodies.
Table A provides an overview of physical setting and utility information for the site.
Table A: Physical Setting and Utility Information
Conditions Source Description
Topography
Elevation (above
mean sea level)
USGS topographic
map; Google
Earth
Ranges from approximately 329 feet on the northern portion of the site to 350 feet on the southern portion of the site.
Topographic
Gradient
USGS topographic
map; visual
observations
Relatively flat on the majority of the site, with a gentle downward slope to the south. Steep downward slope to the stream bed at the north site boundary. Regional topography slopes gently downward to the southwest.
Hydrology
Surface Water
Runoff
Visual
observations
Enters Arroyo Valle stream at the northern site boundary. Enters municipal storm drains in public thoroughfare south of the site.
Percolates into the ground surface at unpaved areas throughout the site.
Nearest Surface
Water Body to the
Site
USGS topographic
map; Google
Earth
Arroyo Valle intersects the northern site boundary. Arroyo Valle flows into Alameda Creek southwest of the site, which then flows into the San Francisco Bay.
Flood Plain FEMA*; site owner Site owner reported no known occurrences of flooding at the site. The northern portion of the site is located within a 100-year flood zone.
Phase I Environmental Site Assessment D R A F T
and Subsurface Investigation
Site Description 7 Ramboll
Table A: Physical Setting and Utility Information
Conditions Source Description
Wetlands NWI*; Visual
observations
There are no federally-designated wetlands on-site, but federally registered wetlands are located approximately 400 feet east of the site in the vicinity of Arroyo Valle.
Geology and Hydrogeology
Presumed
Direction of
Shallow
Groundwater Flow
USGS topographic
map;
Groundwater
monitoring reports
for nearby
properties
reviewed on the
GeoTracker
database
(approximately
600 to 1,000 feet
from the site)
Based on the regional topographic gradient to the west-northwest, shallow groundwater underneath the site is presumed to flow to the west-northwest. Based on nearby property’s groundwater monitoring reports, regional groundwater flow direction is variable. Groundwater monitoring reports for a facility approximately 1,000 feet south of the site (560 Main Street) detected a west-northwest groundwater flow direction. Groundwater monitoring reports for a facility approximately 600 feet northeast of the site (1024 Main Street) detected a north- northeast groundwater flow direction.
Depth to
Groundwater
Groundwater
monitoring reports
for nearby
properties
reviewed on the
GeoTracker
database
Groundwater monitoring reports for nearby properties indicate that depth to groundwater ranges between approximately 30 and 40 feet bgs.
On-site Wells Site owner; visual
observations
No production or monitoring wells onsite.
Nearest
Groundwater
Supply Wells
EDR database
report
One federally-registered public supply well is present between one- eighth of a mile and one-quarter mile south-southeast of the site. Two federally-registered wells and three state-registered wells are present within one-half mile of the site.
Geologic
Conditions
Visual
Observations; soil
boring logs from
nearby properties
reviewed on the
GeoTracker
database
(approximately
1,000 feet south
of the site)
Ramboll observed heterogeneous site soils, predominantly composed of silt, sandy silt, and fine-grained sand to 10 feet bgs. Boring logs from a nearby site indicate that regional soils are fine grained silts and clays to approximately 30 feet bgs, followed by coarser clayey sand and silty gravel to approximately 50 feet bgs (AdvancedGeo Environmental, 2018).
Site Utility Information
Electricity Supplier Site owner Pacific Gas and Electric (PG&E)
Phase I Environmental Site Assessment D R A F T
and Subsurface Investigation
Site Description 8 Ramboll
Table A: Physical Setting and Utility Information
Conditions Source Description
Natural Gas
Supplier
Site owner Pacific Gas and Electric (PG&E)
Use of Fuel Oil for
Building Heat
Site owner No current or former use of fuel oil reported.
Water Supplier Site owner City of Pleasanton
Sanitary Sewer Site owner City of Pleasanton
Septic Systems Site owner No identified current or former septic systems.
Notes:
FEMA = Federal Emergency Management Agency; NWI = National Wetlands Inventory * - Source was provided in the EDR database report.
3.2 Current Use of the Site
The eastern portion of the site is improved with Barone’s, an Italian restaurant, and an outdoor event center. The restaurant occupies the southern portion of the Eastern Parcel. The northern portion of the Eastern Parcel is outdoor dining and event space. The restaurant kitchen (located inside the northern portion of the restaurant building) has a small above-ground grease trap located below the kitchen sinks. None of the current site operations include the use of significant quantities of chemicals. Chemical storage is primarily limited to minor quantities of various detergents and cleaning agents stored in a small partial basement within the kitchen. Additionally, small quantities of paint for restaurant maintenance and gasoline for landscaping equipment are stored within a shed along the western boundary of the restaurant. Multiple small structures along the Eastern Parcel boundaries are used for restaurant and event storage, including furniture, alcohol, glassware, and various outdoor food service equipment.
The southern portion of the Western Parcel is improved with the personal residence of the site owner.
Adjacent to the north of the main residence is an accessory dwelling unit occupied by the site owner’s family. Accessory structures north of the residence include an approximately 150 square-foot structure used as a personal gym, an approximately 200 square-foot single-car garage, an approximately 200 square-foot garage used for restaurant storage, and a small shipping container used for restaurant and furniture storage. The northwest portion of the site is an asphalt paved parking area for the restaurant. The southern portion of the asphalt paved parking area is occupied by a shipping container storing restaurant equipment, an aluminum shed storing wood debris, bikes, and other miscellaneous items, two cargo trailers, dumpsters, and approximately ten empty 20-pound propane tanks.
According to the site owner, site operations have remained generally consistent since he purchased the site in 1995.
Phase I Environmental Site Assessment D R A F T
and Subsurface Investigation
Site Description 9 Ramboll
3.3 Current Uses of Adjoining Properties
The property is located in a mixed residential and commercial land use area. Residential areas are located adjacent to the west of the site. Based on discussions with site owner, Ramboll’s visual observations from the property boundary and public rights-of-way, and a limited review of publicly available information, a general determination of the current use of adjacent properties is described in Table B.
Table B: Current Use of Adjacent Properties
Direction Property/Land Use Ramboll’s Observations
North Arroyo Valle, beyond which is a strip
mall.
No apparent exterior manufacturing or chemical storage
operations were observed. No concerns were noted.
East The Rose Hotel and Farmers Insurance
Office Building.
No apparent exterior manufacturing or chemical storage
operations were observed. No concerns were noted.
South Saint John Street, beyond which is
residential and the Pleasanton
Chamber of Commerce.
No apparent exterior manufacturing or chemical storage
operations were observed. No concerns were noted.
West Residential. No apparent exterior manufacturing or chemical storage operations were observed. No concerns were noted.
Notes:
During the site visit, Ramboll walked or drove by the borders of these properties that are adjacent to the subject site. Ramboll did not enter the neighboring properties to the north or south.
Phase I Environmental Site Assessment D R A F T
and Subsurface Investigation
Review of Public Records and
Other Information Sources 10 Ramboll
4. REVIEW OF PUBLIC RECORDS AND OTHER
INFORMATION SOURCES
4.1 Environmental Regulatory Database Review
Ramboll contracted with EDR in August 2020 to prepare a summary of listings in federal and state agency databases for the site and facilities within applicable radii of the property, as specified by the ASTM standard.0F
1 A copy of the EDR report is presented in Appendix B.
4.1.1 Database Review for Site
Ramboll reviewed the results of the state and federal environmental database searches performed by EDR (see Appendix B) and also searched the GeoTracker and Envirostor online databases. The site, specifically Western Parcel, is listed on environmental databases, as detailed below. • Residential Home (493 Saint John Street). The Western Parcel is listed on the SWEEPS UST database related to a 1,000-gallon unleaded gasoline UST. As detailed in Section 2.2, the SFRWQCB, ACDEH, and the Fire Department did not have documentation of a UST formerly or presently at the site. The site owner was unaware of a UST at the site. However, the former site owner reportedly recalls her husband removing a UST with a backhoe in the 1980s or 1990s.
Based on a hand drawn map from the former site owner (included in Appendix D), the potential former UST was located on the western portion of the site in the vicinity of the trees in the parking lot. Prior to intrusive sampling at the site, Ramboll contracted with Subdynamic Locating Services (Subdynamic) for utility locating. Additionally, Subdynamic scanned the vicinity of the potential former UST with a magnetometer and Ground Penetrating Radar (GPR) but could not detect buried metal or changes in lithology related to a UST or backfill of an excavation.1F 2 Ramboll advanced two
borings (SV03 and SV04) in the vicinity of the potential former UST to 10 feet bgs and collected soil samples. Ramboll field personnel did not observe evidence of any staining or odors. Soil sampling results from 10 feet bgs did not detect total petroleum hydrocarbons as gasoline (TPH- g), diesel (TPH-d), or motor oil (TPH-mo). Soil vapor sampling conducted in the vicinity of the potential former UST location did not detect fuel constituents above regulatory screening criteria (other than benzene, a common detected constituent in parking lots). Soil and soil vapor sampling performed at the site is further discussed in Section 6.
The site is also listed on the following databases related to regulatory compliance: Facility and Manifest Data (HAZNET) and Hazardous Waste Tracking System (HWTS). Listings on these databases, by themselves, are not necessarily indicative of contamination.
4.1.2 Database Review for Adjoining Properties
According to the environmental database search report, no adjoining sites are listed on databases that are indicative of a potential contamination concern.
1 EDR uses the term “radii” to refer to the ASTM terminology “approximate minimum search distance” in the environmental database report.
2 Metal objects including a shed, storage container, and cargo trailers in the vicinity of the potential former UST created interference with the magnetometer and limited the geographic extent of the area scanned by GPR.
Phase I Environmental Site Assessment D R A F T
and Subsurface Investigation
Review of Public Records and
Other Information Sources 11 Ramboll
4.1.3 Database Review for Other Surrounding Properties
Ramboll has identified a number of non-adjoining facilities that represent a potential contamination concern to the subject site due to past releases on these facilities and possible migration onto the subject site, as detailed below.
• Chevron #9-3934 (T0600101715). Chevron #9-3934 is a former gas station located at 780 main street, Pleasanton, California, approximately 250 feet east-southeast and upgradient of the site. The property is listed on the GeoTracker, leaking underground storage tank (LUST), SWEEPS UST, Historical UST (Hist UST), EDR Historical Auto, Cortese, Historical Cortese, California Environmental Reporting System (CERS), and Alameda County Contaminated Sites (CS) databases. Alameda County Local Oversight Program (LOP) issued case closure on January 2, 1996. Additional documentation is not readily available on GeoTracker. Ramboll issued a records request to ACDEH, ACDEH LOP, and the SFRWQCB. The ACDEH and SFRWQCB did not have any records for the facility. The ACDEH LOP has not yet responded to Ramboll’s record request. Based on the case closure status, this property does not present a contamination concern for the subject site.
• Purity Cleaners. Purity cleaners was a former dry-cleaning facility that operated between 1975 and 1982. The facility was located at 722 Main Street, Pleasanton, California, approximately 300 feet southeast and upgradient from the site. The facility is listed on the EDR Historical Cleaner database. While a listing on the database is not indicative of a contamination concern and no other information is known about the facility beside its former operational use, based on the historical use of PCE at dry cleaning facilities during the 1970s and 1980s, this off-site property potentially poses a contamination concern to the subject site. To address the potential contamination concern, soil vapor sampling was performed at the site, as discussed in Section 6.3.
Based on the results of the soil vapor sampling conducted by Ramboll at the site, the Purity Cleaners property is not considered to be of concern for the site. • Main Street Property (T10000008158). Main Street Property was occupied by an auto repair shop from the late 1930s to the late 1960s as well as a gasoline service station from the late 1930s to the early 1950s. The facility is located at 927 Main Street, Pleasanton, California, approximately 350 feet northeast and cross-gradient from the site. The facility is listed on the GeoTracker, LUST, Alameda County CS, Cortese, and CERS databases. Soil, groundwater, and/or soil gas sampling were completed at the facility in November 2015, October 2016, and July 2017 by Environmental Risk Assessors or ATC Associates, Inc. Maximum groundwater concentrations of TPH-g (1,400 micrograms per liter (µg/L)), TPH-d (1,000 µg/L), and total petroleum hydrocarbons as Stoddard Solvent (TPH-ss) (1,400 µg/L) were in excess of the SFRWQCB environmental screening levels (ESLs) of 100 µg/L. The groundwater plume appears to be localized and has not migrated offsite. Additionally, the most proximal groundwater sample to the site did not detect TPH-g, TPG-d, and TPH-ss. The facility received case closure from ACDEH LOP on February 26, 2018 under the SWRCB’s Low Threat UST Closure Policy. ACDEH LOP issued residential land use restrictions for the facility. Based on the case closure documentation the Main Street Property is not considered to be of concern for the site.
• Unocal #0543 (T0600100048). Unocal is a former gasoline service station that had two 10,000-gallon gasoline USTs and one 500-gallon waste oil UST. The facility was located at 992 Main Street, Pleasanton, California, approximately 450 feet northeast and cross-gradient from the site. The facility is listed on the GeoTracker, LUST, Alameda County CS, Cortese, Historical Cortese, SWEEPS UST, Hist UST and CERS databases. Subsurface investigations were conducted
Phase I Environmental Site Assessment D R A F T
and Subsurface Investigation
Review of Public Records and
Other Information Sources 12 Ramboll
at the facility beginning in November 1992. Initial groundwater sampling conducted by MPDS Services, Inc. revealed concentrations of TPH-g and benzene in excess of regulatory screening criteria with concentrations of 1,600 µg/L and 28 µg/L, respectively. Five monitoring wells at the facility were sampled quarterly from September 1993 through January 1995, and only two wells revealed elevated contaminant concentrations. The facility received case closure from the ACDEH LOP on September 12, 1997 due to the relatively small and localized plume. Based on the case closure documentation, the Unocal facility is not considered to be of concern for the site. • Mobil #04-H6J (T0600100909). The former Mobil gas station was located at 1024 Main Street in Pleasanton, California, approximately 500 feet northeast and cross-gradient from the site. The facility is listed on the GeoTracker, LUST, Alameda County CS, Cortese, Historical Cortese, SWEEPS UST, California Facility Inventory Database UST (CA FID UST), Hist UST, and CERS databases. Four USTs were removed from the former service station on October 17, 1989. Soil samples collected during the tank removal revealed TPH-g in soil at concentrations up to 2,400 parts per million (ppm). Approximately 260 cubic yards of soil were excavated beneath the former USTs. In March 1995, vapor and groundwater extraction systems were installed at the facility with four dual-purpose vapor/groundwater extraction wells and five vapor extraction wells.
The system operated for five years, during which, the system processed and discharged 3,854,430 gallons of groundwater and removed 27,218 pounds of hydrocarbons. Groundwater monitoring was conducted at the facility from 1990 to 2009, during which time concentrations of petroleum hydrocarbons generally decreased over time. The facility received case closure from ACDEH Environmental Protection Division on July 14, 2010. Based on the case closure documentation and remediation activities, the Mobil facility is not considered to be of concern for the site. • Family Cleaners (T10000008245). Family Cleaners is a dry-cleaning facility located at 618 Main Street, Suite A, Pleasanton, California, approximately 800 feet south and potentially upgradient from the site. The facility is listed as pending review on GeoTracker and is listed on the Certified Unified Program Agency (CUPA) Listings, EDR Historical Cleaner, and Non-Case Info databases. The facility has operated as a dry cleaner from 1982 to present. The SFRWQCB requested a source investigation because of historic PCE use at the facility. The source investigation, performed by Northgate Environmental Management, inc., identified PCE in soil vapor in excess of the SFRWQCB commercial ESL of 2,100 micrograms per cubic meter (µg/m3) with concentrations up to 9,495 µg/m3. The source investigation also identified PCE in all three grab groundwater samples in excess of the Maximum Contaminant Level of 5 µg/L with concentrations between 7.3 and 11 µg/L. Based on the potential release of PCE from the former dry cleaner and unknown extent of the groundwater plume, this off-site property potentially poses a contamination concern to the subject site. To address the potential contamination concern, soil vapor sampling was performed at the site, as discussed in Section 6.3. Based on the results of the soil vapor sampling conducted by Ramboll at the site, the Family Cleaners property is not considered to be of concern for the site.
• American Cleaners (Former) (T10000008240). The former dry-cleaning facility was located at 555 Main Street, Pleasanton, California, approximately 0.2 miles south and potentially upgradient from the site. The facility is listed as an open case on GeoTracker and the Cleanup Program Sites-Spills, Leaks, Investigations, and Cleanups (CPS-SLIC) databases. A dry-cleaning facility operated from approximately 1920 to 1992. In 2017 and 2018, soil, groundwater, and soil vapor investigations were conducted at the facility by AdvancedGeo Environmental. In 2017, indoor air samples inside the former dry-cleaning facility exceeded the SFRWQCB commercial ESL for PCE of 2.1 ug/m3 with a concentration of 21 ug/m3. In 2018, permanent groundwater monitoring wells and dual-depth soil vapor probes were installed on and off the property. The
Phase I Environmental Site Assessment D R A F T
and Subsurface Investigation
Review of Public Records and
Other Information Sources 13 Ramboll
local groundwater flow direction is to the northwest. The maximum groundwater concentrations of PCE and TCE exceeded the MCL of 5 ug/L with respective concentrations of 20,000 ug/L and 10,000 ug/L. The maximum concentrations of PCE and TCE detected in soil vapor samples were 38,000,000 ug/m3 and 450,000 ug/m3, respectively, in excess of their respective SFRWQCB Commercial ESLs of 2,100 ug/m3 and 3,000 ug/m3. A workplan for additional subsurface characterization and development of a soil vapor extraction system is planned for the property.
Based on the known subsurface impacts of chlorinated solvents from the former dry cleaner and the unknown extent of the groundwater plume, this off-site property potentially poses a contamination concern to the subject site. To address the potential contamination concern, soil vapor sampling was performed at the site, as discussed in Section 6.3. Based on the results of the soil vapor sampling conducted by Ramboll at the site, the Family Cleaners property is not considered to be of concern for the site.
• Pleasanton French Laundry (Former) (T10000008241). Two former dry-cleaning facilities were located nearly adjacent to one another at 220 Division Street and 555 Main Street, Pleasanton, California, approximately 0.2 miles south-southeast of the site and potentially upgradient from the site. The facilities are listed jointly as an open case on GeoTracker and the CPS-SLIC databases. Dry-cleaning operations were conducted at the facilities from approximately 1943 to 1978. In 2019, Trinity Source Group, Inc. conducted active and passive soil vapor sampling, soil sampling, and grab groundwater sampling at the facility. Twenty-six passive soil vapor probes were sampled, four of which detected PCE above the SFRWQCB commercial ESL of 67 ug/m3 with a maximum concentration of 1,777.68 ug/m3. During active soil vapor sampling, nine of ten samples detected PCE above the SFRWQCB commercial ESL of 67 ug/m3. PCE was not detected in groundwater in excess of the California MCL of 5 ug/L. Based on the limited detections of chlorinated solvents in groundwater, this off-site property is unlikely to pose a contamination concern to the subject site.
4.2 Historical Uses of the Site and Adjacent Sites
4.2.1 Past Uses of the Site
Sanborn maps dating back to 1888 indicate the site was originally developed for residential purposes, with two single family residential structures on the southern portion of the site (one residence each where the current residence and restaurant are located). Additionally, between 1888 and 1907, up to five ancillary structures were located in the northern portion of the Eastern Parcel, utilized as a chicken incubator, hen coop, and general storage sheds. By 1953, the additional structures in the northern portion of the Eastern Parcel were removed. The Eastern Parcel was developed into a restaurant by the mid-1970s. In 1995, the restaurant became Barone’s. By 2012, The Eastern Parcel appears in its current configuration with the majority of the parcel landscaped for outdoor dining and events at the restaurant.
Between 1888 and 1907, two ancillary structures were on the Western Parcel, both utilized as a hen house. At least between 1943 and 1953, up to nine structures were one the Western Parcel, utilized as an accessory dwelling unit, paint storage, general storage, and a garage. Between at least 1969 and 1987, the Western Parcel was owned by Loretto Winery, Ltd.; therefore, minor historical agriculture operations may have been conducted at the site. Aerial imagery does not indicate a change from residential operations during the Loretto Winery ownership. By 1998, the Western Parcel appears in its current configuration with the residence remodeled, and the parking lot paved.
Phase I Environmental Site Assessment D R A F T
and Subsurface Investigation
Review of Public Records and
Other Information Sources 14 Ramboll
4.2.2 Interview with Site owner
An interview was conducted during the site visit on September 1, 2020 with Mr. Joseph Barone. Mr.
Barone has been the site owner and restaurant owner, along with his wife Maricela, since 1995. Mr.
Barone’s knowledge of previous tenants and their operations is limited.
According to Mr. Barone, the Western Parcel has always been used as a single-family home. Prior to the Barone’s ownership in 1995, the northern portion of the Western Parcel was undeveloped grassland. Mr. Barone reported that a carriage repair shed was located at the southwest corner of the (now) parking lot prior to the Barone’s ownership. The Barone’s paved the site shortly after purchasing the property. According to Mr. Barone, a single-family home was located on the Eastern Parcel until it was converted to a restaurant called “Casanovas” in the 1980s. Mr. Barone reported no septic tanks currently or historically at the site.
Mr. Barone interviewed the previous owner, who reportedly recalls her former husband removing a UST from approximately the southwest corner of the parking lot, as described in Section 4.1.1. The former site owner provided Mr. Barone with a hand-drawn sketch of the potential former UST location (Appendix D).
According to Mr. Barone, chemical storage has always been limited to the small quantities of paint and cleaning agents that are currently on the site, utilized for general restaurant or residence maintenance. No chemical spills or cleanups have occurred at the site.
A summary of Ramboll’s key observations from the available historical sources is presented in Table C.
Table C: Summary of Key Observations from Historical Sources for the Subject Site Historical Source Key Observations Regarding Site History Sanborn Maps (1888,
1893, 1898, 1903, 1907,
1943, 1953)
The 1888 Sanborn shows the site developed with two residential structures on the southern portion of the site. The parcel lines appear to be changed, separating each parcel in two. One small unmarked structure is shown on the northern portion of the Western Parcel, and two small structures in the northern portion of the Eastern Parcel, one of which is unmarked and the other is a stable.
The 1893 and 1898 Sanborn Maps show the residence on the Western Parcel as having a water tank on the roof and two structures utilized as henhouses in the northern portion of the parcel. The Eastern Parcel shows two structures in the northern portion of the parcel, one a stable and one utilized as a warehouse.
The 1903 Sanborn Map shows the Western Parcel unchanged. The Eastern Parcel has two additional structures (four total) two of which are indicated as hen coops, one as a chicken incubator, and one a wood-shed.
The 1907 Sanborn Map shows the parcel lines in the approximate modern configuration. The Western Parcel had one of the hen house structures removed.
The Eastern Parcel has four sheds and one stable in the northern portion of the parcel.
The 1943 Sanborn Map shows the Western Parcel with an accessory dwelling unit, a garage, a paint storage shed, and five unmarked structures. The Eastern Parcel has one unmarked structure on the northern portion of the parcel.
The 1953 Sanborn Map shows three structures removed from the Western Parcel and only the residence on the southern portion remains. The Eastern Parcel has a garage behind the residence and no other structures on the parcel. No concerns are noted.
Phase I Environmental Site Assessment D R A F T
and Subsurface Investigation
Review of Public Records and
Other Information Sources 15 Ramboll
Table C: Summary of Key Observations from Historical Sources for the Subject Site Historical Source Key Observations Regarding Site History Aerial Photographs and
Satellite Imagery1
(1939, 1940, 1949, 1958,
1963, 1966, 1979, 1982,
1993, 1998, 2003-2020)
The 1939 through 1958 aerial photographs depict the site developed with single- family residences on the southern portion of the site. The majority of the site is undeveloped grassland with a few small structures across the central and northern portions of the site. The 1963 aerial photograph shows the Western Parcel with a garage and an additional shed behind the main residence, but there is not an accessory dwelling unit as depicted in the 1943 and 1953 Sanborn Maps.
Additionally, the Eastern Parcel has a paved driveway to the garage behind the residence. The 1982 aerial photograph shows a structure in the northern portion of the site, potentially a grouping of umbrellas. The 1993 aerial photograph shows changes to the Eastern Parcel after being converted into a restaurant. The 2003 aerial photograph shows the additional dwelling unit adjacent to the north of the residence on the Western Parcel. The 2007 aerial photograph shows the residence on the Western Parcel in its general configuration with the large tress behind the residence removed and additional garage structures present. Aerial photographs from 2007 to 2020 show the site in its current configuration with only minor changes: the shipping container north of the residence appears (2010) and the concrete patio north of the restaurant is extended northward including a concrete path to the northern gazebo (2010). No concerns are noted.
Topographic Maps
(1906, 1941, 1947, 1953,
1961, 1968, 1873, 1980,
2012)
The 1906 through 2012 topographic maps do not show development on the site. No concerns are noted.
City Directory
(1975 and 2014)
The occupants of the 475 Saint John Street address (the Eastern Parcel) are listed as Latrattoria Patio and Villa La (1980); Casanovas Restaurant (1989); Casanovas Ristorante (1995); Barone’s Restaurant and Casanovas (2000); Barone’s (2005); Barone’s Restaurant (2010-2017).
The occupants of the 493 Saint John Street address (the Western Parcel) are listed as Earl Trimingham (1975-1989); unknown occupant (2000); Joseph Barone (2005- 2017).
1 In addition to aerial photographs provided by EDR, Ramboll viewed historical satellite imagery provided via Google Earth. Printed copies were not obtained, and imagery dates were not independently verified.
4.2.3 Past Uses of Adjacent Sites
From the late 1800s, the property adjacent to the west of the site was a single-family dwelling unit with accessory structures that stored oil and paint. By 1943, Garatti Winery processing facility was developed adjacent to the west of the site. By 1993, the residential complex adjacent to the west of the site was developed. Properties south of the site were primarily used for residential land use starting in the late 1800s and have become mixed-use residential and commercial over time.
Properties north of the site, beyond Arroyo Valle, were mostly undeveloped land until the construction of Del Valle Parkway in 1993; beyond which is commercial land use including a former vehicle service station (see “Main Street Property” in Section 4.1.1). Since the late 1800s, the properties east of the site have primarily been used for commercial operations (carriage painting, hotels, printing shop, etc.). By 2003, the Rose Hotel and Farmers Insurance building east of the site appear in their modern configuration.
Phase I Environmental Site Assessment D R A F T
and Subsurface Investigation
Review of Public Records and
Other Information Sources 16 Ramboll
4.3 Review of Local and State Agency Information
Ramboll visited or otherwise contacted local governmental agencies and regulatory bodies for information relating to the site. An overview of the findings of this review is presented in Table D.
Table D: Local Agency Information for the Site
Agency Contacted /
Document Reviewed Information Obtained
Alameda County
Assessor
A parcel map for the site area was reviewed at the Alameda Clara County Assessor’s website. The Alameda County parcel map depicts the site APNs as 94-114-7 and 94- 114-8.
City of Pleasanton
Building Department
Ramboll reviewed available public records delivered to Ramboll electronically by the Building Department. Building Department records included design reviews and construction permit applications by James Fazzari starting in 1988 for additions to Casanova’s Ristorante at 475 Saint John Street. Records also included various construction permit applications by the Barones starting in 1995 for both improvements to the restaurant at 475 Saint John Street and the residence at 493 Saint John Street.
City of Pleasanton Fire
Department
Ramboll requested any available records from the City of Pleasanton Fire Department. The Fire Department did not have any records in regards to USTs or in regards to the Western Parcel. The Eastern Parcel has inspection reports with violations for servicing the fire extinguisher, dry rot on the back deck of the restaurant, and required earthquake strapping for the water heater.
Alameda County
Department of
Environmental Health
Ramboll requested any available records from the ACDEH for information regarding soil or groundwater investigations, USTs, LUSTs, hazardous materials inspections, or violations/permits for the site. Ramboll was informed that no records were found for the site addresses.
4.4 Previous Environmental Assessments and Activities
No previous environmental assessments have been conducted at the site.
4.5 Environmental Lien Record Search
A review of EDR Environmental Lien Search Report dated September 1, 2020 was conducted to identify environmental liens or AULs imposed by judicial authorities with respect to APNs 94-114-7 and 94-114-8. No environmental liens or AULs were found. The EDR Environmental Lien Search Report is attached as Appendix E.
4.6 User-Provided Information
Ramboll provided Robson Homes with a User Questionnaire (consistent with Appendix X3 of the ASTM Standard) that requested information relating to environmental liens, AULs, specialized knowledge of the property, property value diminution, chain-of-title, or any other commonly known or obvious indications of site contamination, that was not otherwise provided to Ramboll. The user did not provide any information that was not otherwise obtained and reviewed by Ramboll.
Phase I Environmental Site Assessment D R A F T
and Subsurface Investigation
Site Reconnaissance 17 Ramboll
5. SITE RECONNAISSANCE
5.1 Methodology and Limiting Conditions
Ramboll conducted multiple site visits in September and October 2020. During the site visits, observations of the site were made to evaluate if any RECs, as defined in Chapter 2, are present.
5.2 General Site Setting and Observations
Ramboll made observations concerning all issues specified in Sections 9.4.2 through 9.4.4 of the ASTM E1527-13 Standard. The presence or absence of each issue of environmental interest or concern is noted in Table E. Additional information regarding observed and historical items is provided in the sections following the table.
Table E: Summary of Site Reconnaissance Observations
Issue ASTM
Section Observation
Interior and Exterior Issues
Current use(s) of the property 9.4.2.1 See Section 3.2
Past use(s) of the property 9.4.2.2 See Section 4.2
Hazardous substances and petroleum products used, treated, stored, disposed of, or generated on the property in connection with identified present or past uses
9.4.2.3 Present
(see Section 5.2.1)
Storage tanks:
Underground storage tanks (fill ports, vent pipes, manholes)
Aboveground storage tanks
9.4.2.4 Potentially Historically
Present (see Section 5.2.2)
Absent
Odors (strong, pungent or noxious) 9.4.2.5 Absent
Pools of liquid, standing surface water or sumps 9.4.2.6 Present (see Section 5.2.3)
Drums of hazardous substances or petroleum products
(five-gallon, 55-gallon or totes)
9.4.2.7 Present
(see Section 5.2.1)
Hazardous substance and petroleum product containers
(not necessarily in connection with identified uses)
9.4.2.8 Present
(see Section 5.2.1)
Unidentified substance containers suspected of containing hazardous substances or petroleum products
9.4.2.9 Absent
Phase I Environmental Site Assessment D R A F T
and Subsurface Investigation
Site Reconnaissance 18 Ramboll
Table E: Summary of Site Reconnaissance Observations
Issue ASTM
Section Observation
Polychlorinated biphenyls (PCBs)
Electrical equipment on-site (e.g., transformers, capacitors) Electrical equipment known or likely to contain PCBs
Hydraulic equipment on-site (e.g., elevators, truck dock lifts) Hydraulic equipment known or likely to contain PCBs
9.4.2.10 Absent
Absent
Absent
Absent
Interior Issues
Heating/cooling systems 9.4.3.1 Present
Stains or corrosion on interior floors, walls or ceilings (except for staining from water)
9.4.3.2 Absent
Floor drains and interior sumps 9.4.3.3 Present
(see Section 5.2.3)
Exterior Issues
Pits, ponds or lagoons on property or adjacent sites 9.4.4.1 Absent Stained soil or pavement 9.4.4.2 Absent
Stressed vegetation (from other than insufficient water) 9.4.4.3 Absent On-site solid waste disposal; areas apparently filled or graded by non-natural causes; or mounds or depressions suggesting solid waste disposal
9.4.4.4 Absent
Wastewater or other liquid (including storm water) or any discharge into a drain, ditch, underground injection system or stream on or adjacent to the property
9.4.4.5 Present
(see Section 5.2.4)
Wells (including dry wells, irrigation wells, injection wells, abandoned wells, or other wells)
9.4.4.6 Absent
Septic systems or cesspools 9.4.4.7 Absent
Notes:
Observations noted in this table and discussed further below are based on information obtained during the site visit and from a review of the sources summarized in Section 4.
See the ASTM Standard for a detailed description of the issues included in each referenced ASTM section.
Per the ASTM Standard, fluorescent light ballasts likely to contain PCBs do not need to be noted.
N/A – Not applicable
Phase I Environmental Site Assessment D R A F T
and Subsurface Investigation
Site Reconnaissance 19 Ramboll
5.2.1 Hazardous Material Use and Storage
During Ramboll’s site visits in September 2020, the only petroleum products identified were two high density polyethylene (HDPE) five-gallon gasoline canisters used for fueling landscaping equipment.
The gasoline canisters were stored on the floor inside a shed northwest of the restaurant. Multiple 20- pound propane tanks, which are utilized to fuel space heaters at the outdoor dining area, are present north of the restaurant. Additionally, multiple containers of paint and stain are stored in one and five- gallon containers in storage sheds north of the restaurant. Multiple one-gallon containers of washing machine detergent, surface cleaners, and dish soaps are stored on a shelving unit in the partial- basement area of the kitchen. The only chemicals Ramboll observed in the on-site residence were small quantities of general cleaners. No evidence of release was observed in any of the aforementioned areas.
5.2.2 Potential Historical UST
As discussed in Section 4.1.1, the former site owner reportedly recalls her husband removing the UST from the southwest corner of the parking lot in the early 1990s and provided a hand-drawn sketch of the possible location (see Appendix D). Ramboll contacted the Fire Department, ACDEH, and RWQCB, but none of the agencies reported having records of a UST. As discussed in Section 4.1.1, Subdynamic scanned the vicinity of the potential former UST with a magnetometer and Ground Penetrating Radar (GPR) but could not detect buried metal or changes in lithology related to a UST or backfill of an excavation. Ramboll advanced two borings to 10 feet bgs in the vicinity of the potential former UST. No soil staining, odors, or other evidence of a release were observed by Ramboll field personnel. Soil sampling conducted in the vicinity of the potential former UST location did not detect fuel constituents. Soil vapor sampling conducted in the vicinity of the potential former UST location detected benzene slightly above the residential regulatory screening criteria at one of the two locations in the vicinity of the potential former UST (SV04); however, SV04 is in the parking lot and concentrations of benzene are commonly detected in vehicle use areas. No additional fuel constituents or by-products were detected in soil vapor samples above regulatory screening criteria for unrestricted residential land use.
5.2.3 Pools of Liquid, Standing Surface Water, or Sumps During the September 2020 site walk, the site owner stated there are a total of five sumps beneath the Western Parcel. Two of the sumps are located below the residence for the basement and three of the sumps are located in the landscaping in the front of the house. The sumps are utilized for flood control. No sumps are located on the Eastern Parcel.
5.2.4 Stormwater
Stormwater runoff at the site primarily discharges onto the street and eventually to the municipal storm drains on Saint John Street. However, some stormwater likely discharges to Arroyo Valle, the stream intersecting the northern portion of the site.