Agenda packet, regular meeting — La Mesa City Council, May 13, 2025 (part 11 of 15)

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*Recorded by Ahmanson, Dudek *Date February 12, 2024  Continuation  Update DPR 523L (9/2013) *Required information
State of California - The Resources Agency Primary#
DEPARTMENT OF PARKS AND RECREATION HRI #
CONTINUATION SHEET Trinomial
any individuals who inhabited the subject property who played an important role in history. Therefore, 5810 Amaya Drive is not eligible under NRHP Criterion B or CRHR Criterion 2.

Criterion C/3: [Properties] that embody the distinctive characteristics of a type, period, or method of construction, or that represent the work of a master, or that possess high artistic values, or that represent a significant and distinguishable entity whose components may lack individual distinction.

The subject property is a modest and architecturally undistinguished example of a multifamily residential complex with no particular style. It is a ubiquitous example of its type and there are many similar examples in La Mesa, San Diego County, and California. According to its original building permit, the architect of 5810 Amaya Drive was Robert T. Peters. Research, through Newspapers.com, Calisphere, Ancestry.com, and the American Institute of Architects Historical Directory, did not identify additional information on Robert T. Peters. It appears unlikely that the property was constructed by a master architect or builder.

The subject property appears to have been constructed through already well-documented and common construction techniques and methods and does not appear to possess high artistic values by articulating a particular concept of design to the extent that it expresses an aesthetic ideal. The last portion of Criterion C refers to a district, which is defined as a significant and distinguishable entity whose components may lack individual distinction. The subject property does not contribute to the significance of a potential or existing historic district. Overall, 5810 Amaya Drive lacks sufficient design and construction value to meet NRHP Criterion C or CRHR Criterion 3.

Criterion D/4: [Properties] that have yielded, or may be likely to yield, information important in prehistory or history.

Under NRHP Criterion D and CRHR Criterion 4, 5810 Amaya Drive is not significant as a source, or likely source, of important historical information, nor does it appear likely to yield important information about historic construction methods, materials, or technologies. This technology is well understood through contemporary trade journals and scientific monographs. As such, the subject property lacks significance under NRHP Criterion D and CRHR Criterion 4.

City of La Mesa Evaluation
A cultural resource may be recommended for designation as a landmark or historic district, if it meets one or more of the following criteria:

A. It exemplifies or reflects special elements of the City's cultural, social, economic, political, aesthetic, engineering, or architectural history.

As discussed under NRHP/CRHR Criteria A/1 and C/3, the subject property does not exemplify or reflect special elements of the City’s cultural, social, economic, political, aesthetic, engineering, or architectural history. It is a multi-family residential apartment complex constructed in 1970 during a period of rapid residential development throughout La Mesa. As such, the subject property is recommended not eligible under City of La Mesa Criteria A.

B. It is identified with persons or events significant in local, state, or national history.

As discussed under NRHP/CRHR Criteria B/2, the subject property is not associated with a significant person or events in local, state, or national history. As such, the subject property is recommended not eligible under City of La Mesa Criteria B.

C. It embodies distinctive characteristics of a style, type, period, or method of construction, or is a valuable

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As discussed under NRHP/CRHR Criteria C/3, the subject property is a common 1970s apartment complex. It is constructed of already well-documented materials and techniques and is not a valuable example of the use of indigenous materials or craftsmanship. As such, the subject property is recommended not eligible under City of La Mesa Criteria C.

D. It is representative of the notable work of an acclaimed builder, designer, or architect.

As discussed under NRHP/CRHR Criteria C/3, the subject property is not representative of a notable work of an acclaimed builder, designer, or architect. As such, the subject property is recommended not eligible under City of La Mesa Criteria D.

E. It is identified with a person or persons or groups who significantly contributed to the culture and development of the City.

As discussed under NRHP/CRHR Criterion B/2, the subject property is not associated with a person or group who significantly contributed to the culture and development of the City. As such, the subject property is recommended not eligible under City of La Mesa Criteria E.

F. It embodies elements of outstanding attention to architectural design, detail, materials or craftsmanship.

As discussed under NRHP/CRHR Criteria C/3, the subject property does not embody elements of outstanding attention to architectural design, detail, materials, or craftsmanship. It is a ubiquitous, stylistically undifferentiated 1970 multi-family residential complex constructed with already well documented materials. As such, the subject property is recommended not eligible under City of La Mesa Criteria F.

G. It is an archeological or paleontological site which has the potential of yielding information of scientific value.

As discussed under NRHP/CRHR Criteria D/4, the subject property is not an archaeological or paleontological site which has the potential of yielding information of scientific value. As such, the subject property is recommended not eligible under City of La Mesa Criteria G.

H. It is a geographically definable area possessing a concentration of sites, buildings, structures, improvements, or objects linked historically through location, design, setting, materials, workmanship, feeling, and/or association, in which the collective value of the improvements may be greater than the value of each individual improvement.

As discussed under NRHP/CRHR Criteria 3, a geographically definable area possessing a concentration of associated buildings or sites is most applicable to districts. While the subject property is located in a neighborhood of single and multifamily residences constructed in the same time period, there are many such neighborhoods throughout La Mesa and research did not identify this neighborhood as having significant historical associations. As such, the subject property is recommended not eligible under City of La Mesa Criteria H.

Integrity Considerations
Because 5810 Amaya Drive lacks sufficient significance to meet any of the criteria for listing in the NRHP, CRHR, or as a City of La Mesa Historic Landmark, an integrity analysis was considered immaterial. To be eligible for listing in either register, a resource must first meet one or more of the significance criteria outlined above before a determination can be made as to whether the resource retains its historic character and can convey its significance.

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*Recorded by Ahmanson, Dudek *Date February 12, 2024  Continuation  Update DPR 523L (9/2013) *Required information
State of California - The Resources Agency Primary#
DEPARTMENT OF PARKS AND RECREATION HRI #
CONTINUATION SHEET Trinomial
Summary of Evaluation Findings
The subject property was evaluated in consideration of NRHP, CRHR, and City of La Mesa criteria and integrity requirements.

As a result of the evaluation, the subject property is recommended not eligible for inclusion in the NRHP, CRHR, or as a City of La Mesa Historic Landmark under all listing criteria due to a lack of significant associations and architectural merit. The subject property is not currently designated or listed under any national, state, or local landmark programs, nor has it been previously identified as eligible for local designation by any historical resource surveys. *B12. References (continued from page 2):

Caltrans (California Department of Transportation). 2011. “Tract Housing in California, 1945-1975: A Context for National Register Evaluation.” Sacramento, CA. 2011. https://dot.ca.gov/-/media/dotmedia/programs/environmental-analysis/documents/ser/tract-housing-in-ca-1945-1973-a11y.pdf.

City of La Mesa Building Permits. 2024. Permit files. Received February 27, 2024.

City of La Mesa. 2012. City of La Mesa General Plan: Historic Preservation Element. https://www.cityoflamesa.us/DocumentCenter/View/6201/07LaMesaGPHistoricPreservation-CD?bidId=.

City of San Diego Planning Department. 2007. “San Diego Modernism Historic Context.” Submitted for the State of California Office of Historic Preservation. San Diego, CA. October 17, 2007. chromeextension://efaidnbmnnnibpcajpcglclefindmkaj/https://www.sandiego.gov/sites/default/files/modernism_2 007.pdf.

Horak, Katie E., Andrew Goodrich, Alan Hess, and John English. 2015. Los Angeles Citywide Historic Context Statement: Architecture and Engineering; Theme: The Ranch House, 1930-1975; Theme: Housing the Masses, 1880-1975; Sub-Theme: Ranch House Neighborhoods, 1938-1975. Prepared for City of Los Angeles, Department of City Planning, Office of Historic Resources. http://preservation.lacity.org/sites/default/files/The%20Ranch%20House%2C%201930-1975.pdf McAlester, V.S. 2015. A Field Guide to American Houses (Revised): The Definitive Guide to Identifying and Understanding America's Domestic Architecture. New York City, New York: Alfred A Knopf.

Morgan, W. 2004. The Abrams Guide to American House Styles. New York City, New York: Harry N Abrams Inc.

NETR (National Environmental Title Agency). 2024a. “Historic Aerials Online.” Historic Aerial Photographs: 1953, 1964, 1966, 1978, 1980, 1981, 1982, 1983, 1984, 1985, 1985, 1987, 1988, 1989, 1990 1991, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2002, 2003, 2005, 2009, 2010, 2012, 2014, 2016, 2019.

Accessed February 5, 2024. https://www.historicaerials.com/viewer.

NETR. 2024b. “Historic Aerials Online.” Historic Topography Maps: 1893, 1897, 1901, 1903, 1909, 1916, 1930, 1941, 1942, 1947, 1955, 1956, 1959, 1964, 1969, 1975, 1976, 1978, 1986, 2001, 2012, 2015, 2018, and 2021. Accessed February 5, 2024. https://www.historicaerials.com/viewer.

ParcelQuest. 2024. Accessed March 4, 2024. https://pqweb.parcelquest.com/#home.

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*Recorded by Ahmanson, Dudek *Date February 12, 2024  Continuation  Update DPR 523L (9/2013) *Required information
State of California - The Resources Agency Primary#
DEPARTMENT OF PARKS AND RECREATION HRI #
CONTINUATION SHEET Trinomial
U.S. Department of the Interior (USDOI). 2002. “National Register Bulletin 15: How to Apply the National Register Criteria for Evaluation.” National Park Service, Cultural Resources. Accessed December 2023. https://www.nps.gov/subjects/nationalregister/upload/NRB-15_web508.pdf.

Photograph 2. Driveway entrance to 5810 Amaya Drive, view looking north. Photograph taken on February 12, 2024 (Dudek IMG_4239).

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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 6Z
Other Listings
Review Code Reviewer Date
P1. Other Identifier: Map ID 14
*P2. Location: ☐ Not for Publication ☒ Unrestricted
*a. County San Diego and (P2c, P2e, and P2b or P2d.
*b. USGS 7.5' Quad San Bernardino Date 2023 T 16S; R 1W; ☐ of ☐ of Sec 16; San Bernardino B.M. c. Address: 9320 Earl Street City: La Mesa Zip: 91942
d. UTM: (Give more than one for large and/or linear resources) Zone 11N mE/ 500413 mN 3627843 e. Other Locational Data: APN 486-670-27
*P3a. Description: (Describe resource and its major elements. Include design, materials, condition, alterations, size, setting, and boundaries)
The subject property at 9320 Earl Street (APN 486-670-27), also known as Grossmont Village, is a condominium complex, located on the northeast side of Earl Street. The complex contains 11 one-story multi-family residential buildings comprising a total of approximately 150 condominiums. Each building is rectangular in plan with stucco siding and composition tile hipped roofs with overhangs and closed eaves (Photographs 1-3). Board-and-batten gables are located at the ends of each roof. See Continuation Sheet, Page 4.
*P3b. Resource Attributes: HP3. Multiple Family Property *P4. Resources Present: ☒ Building ☐ Structure ☐ Object ☐ Site ☐ District ☐ Element of District ☐ Other P5b. Description of Photo 1:

Photo 1: west elevation of a multifamily building, view looking east (Dudek IMG_4244)
P6. Date Constructed/Age and
Source: ☒ Historic. 1963 (City of
La Mesa Permits #18686 and
#19147
*P7. Owner and Address:

Robert S. and Carol J. Haller
497 Sandy Run Drive
Sparta, GA 31087
*P8. Recorded by:

Katie Ahmanson, MHC
Dudek
225 S Lake Ave, Suite M210
Pasadena, CA 91101
*P9. Date Recorded:

February 12, 2024
*P10. Survey Type: Intensive
*P11. Report Citation: Dudek. 2024. Built Environment Inventory and Evaluation Report for 9407 Jericho Road Project.

Prepared for the City of La Mesa.
*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 ☒Sketch Map ☐Other (List):

P5a. Photograph 1.

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*Resource Name or # (Assigned by recorder) 9320 Earl Street 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: N/A
B2. Common Name: N/A
B3. Original Use: Single-family residence B4. Present Use: Single-family residence *B5. Architectural Style: Undifferentiated
*B6. Construction History: (Construction date, alterations, and date of alterations) The following exterior alterations to 9320 Earl Street were identified the field survey:
• Unknown date: addition of metal security screen doors (observed) • Unknown date: replacement window frames on several condominium units (observed) *B7. Moved? ☒No ☐Yes ☐Unknown Date: Original Location:
*B8. Related Features: None.

B9a. Architect: Stan Ring b. Builder: Walter G. Kurz
*B10. Significance: Theme N/A Area N/A
Period of Significance N/A Property Type N/A Applicable Criteria N/A (Discuss importance in terms of historical or architectural context as defined by theme, period, and geographic scope. Also address integrity.)
The single-family residence at 9320 Earl Street was evaluated for historical significance in consideration of National Register of Historic Places (NRHP), California Register of Historical Resources (CRHR), and City of La Mesa Historic Landmark designation criteria. The subject property was found not eligible due to a lack of significant associations and architectural merit. The subject property was also evaluated in accordance with Section 15064.5(a)(2)-(3) of the California Environmental Quality Act (CEQA) Guidelines using the criteria outlined in Section 5024.1 of the California Public Resources Code (PRC) and found not to be a historical resource for the purposes of CEQA. As such, this evaluation assigns a 6Z California Historical Resources Status Code to 9320 Earl Street. See Continuation Sheet, Page 5.

B11. Additional Resource Attributes: None
*B12. References: See Continuation Sheet, Page 11
B13. Remarks: None
*B14. Evaluator: Claire Cancilla, MSHP
*Date of Evaluation: March 18, 2024

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*Map Name: El Cajon Quadrangle *Scale: 1:24000 *Date of map: 2021 DPR 523J (9/2013) *Required information
State of California - The Resources Agency Primary #
DEPARTMENT OF PARKS AND RECREATION HRI#
LOCATION MAP Trinomial

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Fenestration consists of vinyl and metal-frame horizontal sliding windows, vinyl-frame double-hung and fixed windows, and single-leaf doors obscured by metal security screen doors. An asphalt driveway leads to parking lots on west, south, and east boundaries of the property. Landscaping throughout the complex includes winding concrete paths, grass, bushes, and mature trees (Photographs 2 and 3). Only partial views of the buildings were visible from the public right-of-way during the survey on February 12, 2024.

Photograph 2. The primary (east) elevation of a multi-family building at 9320 Earl Street, view looking west.

Photograph taken on February 12, 2024 (IMG_6969).

Photograph 3. The primary (south) elevation of a multi-family building at 9320 Earl Street, view looking northwest.

Photograph taken on February 12, 2024 (IMG_6960.JPG).

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*B10. Significance (continued from page 2):

Historic Contexts
The City of La Mesa’s 2012 General Plan Historic Preservation Element includes a historical overview of the city’s establishment and development. This overview is reproduced below to provide sufficient context through which to evaluate the subject property:

Founded in 1869, the lands comprising present-day La Mesa were initially within the boundaries of Rancho Mission San Diego de Alcala. The area was first settled in the American Period, in approximately 1868, when Robert Allison purchased property for use as a sheep ranch and other animal husbandry activities. In 1887 Allison purchased construction bonds and granted a right-of-way to the new San Diego, Cuyamaca, and Eastern Railroad Company. By 1895, newspapers and periodicals referenced La Mesa as “Allison Springs,” “La Mesa Springs,” and “La Mesa Colony.” Into the early twentieth century the local economy expanded to include agriculture and citrus orchards with packing warehouses, health resorts and limited film production facilities. By 1912, at the time of incorporation, the city’s population had reached 700 (City of La Mesa 2012: HP-2).

Construction of El Cajon Boulevard, around the time of World War I, provided for an alternative transportation route between San Diego and La Mesa. By 1930 La Mesa’s population increased to 2,500, however, because of the Great Depression, little growth occurred until the onset of World War II and beyond, when La Mesa and municipalities throughout the entire State experienced tremendous growth in the form of new residential tracts and suburban commercial centers (City of La Mesa 2012: HP-3).

By 1940 the city’s population reached 3,912. Subsequent to WWII, La Mesa’s population increased exponentially, and the municipality was soon regarded as one of the fastest growing suburban cities in the San Diego region.

Infrastructure demands and land annexations characterize the post-World War II period of La Mesa’s history, with the development of comprehensively constructed residential tracts improved with dwellings in modernistic Ranch style, replete with new schools and shopping centers to support the growing population. Housing stock and forms changed to reflect the rise of modernistic residential subdivision tracts. These new communities were connected by major transportation corridors developed in the mid-to-late 1950s, including SRs 94 and 125 (City of La Mesa 2012:

HP-3).

By the early 1950s, the student population in La Mesa and the surrounding jurisdictions had peaked with a record enrollment of 3,000 at Grossmont High School. The overcrowding demanded an immediate solution in the form of two new schools opening in 1952, La Mesa Junior High School and Helix High School. New commercial developments were similarly plentiful, culminating in the 1961 opening of Grossmont Shopping Center, the second regional mall built in San Diego County (City of La Mesa 2012: HP-4).

As economical vacant land was consumed by new single-family neighborhoods; rising land costs in the older parts of La Mesa created a demand for higher-density cost-effective housing which, in the 1950s and 1960s, resulted in the development of infill apartment buildings in and around established historic-era neighborhoods. Inconsistent in appearance and form from the preceding historic-era neighborhoods, these infill projects were constructed in a mix of minimal and Modernistic styles, which contributed to the erosion or replacement of some older neighborhoods and buildings. This trend was reversed in the 1970s as citizens of La Mesa initiated historic preservation efforts

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CONTINUATION SHEET Trinomial
culminating in the adoption of the city’s inaugural Historic Preservation Program in the mid-1980s, including adoption of the city’s first Historic Preservation Element (City of La Mesa 2012: HP-4).

Post-World War II Tract Housing (1945-1975)
During World War II, manufacturing jobs were abundant in California while housing was lacking, resulting in many workers living in vehicles, tents, and other temporary shelters. Despite the passing of the Lanham Act in 1940, which appropriated $1.3 billion for the construction of 700,000 homes, the War Production Board prohibited non-essential construction during wartime including market-driven housing in 1942. This resulted in an enormous lack of housing, with construction being limited to single-family tracts for industry workers and cheap and quickly built multi-family housing intended to be temporary (Caltrans 2011: 5).

The government programs intended to assist working-class families and veterans to purchase a house contributed to a postWorld War II development boom. These included the G.I. Bill created to help veterans of World War II pay for additional education and Veterans Affairs (VA) loans for purchasing homes. These benefits were disproportionately given to white veterans due to systemic racism and unfair government practices. In 1950, the Federal Housing Authority (FHA) attempted to address this racial discrimination by deciding to refuse insuring mortgages on properties subject to restrictive covenants (Mead & Hunt and Louis Berger Group, Inc. 2012: 56). In November of 1962, President Kennedy issued an Executive Order prohibiting racial discrimination in all housing that received federal aid, including FHA and VA mortgage guarantees (Caltrans 2011: 30). California passed its owns open-housing legislation known as the Unruh Act in 1959. This was followed by the Rumford Act in 1963, which specifically prohibited racial discrimination by banks, real estate brokers and mortgage companies. With the government programs and new housing opportunities, racial residential patterns slowly began to change in California.

Two popular trends in post-World War II housing development were tract housing and cluster planning. Residential tracts allowed for builders to defray the cost of providing utilities resulting in many cities growing not one house at a time, but rather by adding entire new subdivisions (Caltrans 2011: 43-48). Developers started to hire architects not to design a single home but rather a set of stock plans, resulting in new communities of 300-400 nearly identical homes (City of San Diego Planning Department 2007: 36-39). Tract communities display common elements in design, creating clusters of similar houses having the same basic architectural detailing, scale, style, and setting usually around curvilinear streets. Between 1949 and 1966, Eichler Homes, Joseph Eichler’s company, created neighborhoods that were planned communities with concentric circle street plans and shared amenity spaces such as parks, community centers, and pools. These subdivisions influenced the designs of other developers to include modern design, livability, and economy (City of Palo Alto 2018: 33-36). Frequently the architectural styles of Tract Ranch and Contemporary were employed, with developers typically offering four or five models each with customizable features (City of San Diego Planning Department 2007: 39). Customizable features could include, rooflines, exterior cladding materials, light fixtures, cabinetry, and kitchen finishes. In the 1960s, the concept of cluster planning became popular which involved setting aside a portion of green space with the surrounding housing being more densely grouped on the remaining land. Cluster planning provided public spaces such as parkland, pedestrian and bicycle paths. This allowed developers to move less earth and remove fewer trees, which local governments often supported. It was a trend supported by local governments and environmentalists. It was also economically beneficial for developers because they could avoid areas where it would be costly to develop and reduced their costs for infrastructure like water and sewer lines (Caltrans 2011: 49).

La Mesa’s residential development history reflects a combination of the tract housing development type and the cluster planning. Within the API, all of the subject properties are located in Tract 5572 in the Northmont neighborhood La Mesa

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followed a similar design aesthetic to the nearby neighborhood of Clairemont in that it contains Tract Ranch and Contemporary master-planned neighborhoods, which became ubiquitous in the region’s post-World War II era. Some of the most common examples of multi-family residences are townhomes, apartment buildings, condominium complexes, and duplexes. Popular architectural styles employed to design residential properties include Tract Ranch and Contemporary (City of San Diego Planning Department 2007: 40-49)
Property History
Grossmont Village condominiums located at 9320 Earl Street were constructed in 1963 (City of La Mesa Permits #18686 and #19147; NETR 2024). Prior to its construction, the lot on which the complex sits was undeveloped. According to original building permits from the property’s construction in 1963, the architect was Stan Ring. Research identified a Stan Ring who, in 1984, owned Taylor Paper Tubes Company, which produced cardboard tubes (Hardy 1984: 34) According to a newspaper article about the business, Ring "started looking for a new source of income after deciding to get out of the real estate business" (Hardy 1984: 34). Research did identify additional information on Ring’s career, any memberships in professional architecture organizations, or additional architectural projects. The contractor is listed as the complex’s original owner, Walter G. Kurz (City of La Mesa Permits #18686 and #19147). Besides what is listed in Table 19, research did not identify additional biographical or professional information on Kurz, nor did it identify additional projects constructed by Kurz.

Dudek received 345 pages of building permits from the City of La Mesa for 9320 Earl Street. Because of the number of owners and residents (66) for this large complex, Table 1 below is limited to information on identified property owners or residents who verifiably owned or occupied a condominium in the complex for two years or longer. Information on these occupants primarily comes from building permits associated with the property; some of these permits included ownership information that was limited to an individual’s last name with no identifying first name or other biographical information. As such, these names are excluded from the table below.

Table 1. Selected Owners/Occupants of Grossmont Village, 9320 Earl Street Years Name Notes Source
1963-1964 Walter G. Kurz Walter G. Kruz was the original owner/developer of the Grossmont
Village condominiums. In the 1963 City
of San Diego directory, he was listed as a
contractor.

City of La Mesa Permits
#18686 and #19147
Ancestry.com
1979-1982 Eddie and Judy Simon (Apt. #20) Research did not identify information on Eddie or Judy Simon.

City of La Mesa Permits
#42783 and #46007
1981-1984 Margaret Ellis O’Neal (Apt. #60) Research did not identify substantive biographical or professional information
on Margaret Elis O’Neal (1900-1992).

Per the 1973 San Diego directory,
Margaret O’Neal was retired at that time.

City of La Mesa Permits
#45740 and #48392
Ancestry.com
1982-2018 Betty J. Kandt (Apt. #37) Research did not identify information on Betty J. Kandt.

City of La Mesa Permits
#47980 and #B18-1040
1994-2009 Judith Peterson (Apt. #33) Research did not identify information on Judith Peterson.

City of La Mesa Permits
#69325 and #P09-055
2002-2005 Donna Cross (Apt. #48) Research did not identify information on Donna Cross.

City of La Mesa Permits #B02-
318 and #B05-539
2002-2020 Eileen M. Black (Apt. #15) Research did not identify information on Eileen M. Black.

City of La Mesa Permits #P02-
003 and #M20-088

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*Recorded by Ahmanson, Dudek *Date February 12, 2024  Continuation  Update DPR 523L (9/2013) *Required information
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Table 1. Selected Owners/Occupants of Grossmont Village, 9320 Earl Street Years Name Notes Source
2012-2024 Robert S. and Carol J. Haller Research did not identify information on Robert S. and Carol J. Haller.

ParcelQuest 2024
NRHP/CRHR Evaluation
The following section provides an evaluation of the single-family residence at 9320 Earl Street under NRHP and CRHR significance criteria and integrity considerations.

Criterion A/1: [Properties] that are associated with events that have made a significant contribution to the broad patterns of our history.

Grossmont Village, a multifamily condominium complex located at 9320 Earl Street, was constructed in 1963. Following World War II's conclusion in 1945, La Mesa's population increased dramatically and the "municipality was soon regarded as one of the fastest growing suburban cities in the San Diego region" (City of La Mesa 2012: HP-3). The subject property was thus part of the La Mesa’s growth post-World War II to accommodate the needs of an influx of new residents. While the post-World War II growth was an important trend regionally and in California, this property did not play a significant role in this trend. It was one of many constructed during this period of growth and did not influence this trend. It is also not known to be directly associated with events that have made a significant contribution to the history of the City of La Mesa, California, or the nation. Research also did not identify a significant historical event that occurred on the property. Therefore, 9330 Earl Street is not eligible under NRHP Criterion A or CRHR Criterion 1.

The subject property was thus part of a period of rapid residential development in La Mesa following World War II that accommodated the city’s exponential population growth. However, mere association with a broad trend is not enough to reach the threshold of eligibility and the property is not known to be directly associated with events that have made a significant contribution to the history of the City of La Mesa, California, or the nation. Research also did not identify a significant historical event that occurred on the property. Therefore, 9330 Earl Street is not eligible under NRHP Criterion A or CRHR Criterion 1.

Criterion B/2: [Properties] that are associated with the lives of persons significant in our past.

Grossmont contains approximately 150 condominiums. Building permit research identified numerous occupants from the property’s construction to the present day. Residents who verifiably resided at Grossmont Village for more than two years are as follows: Eddie and Judy Simon (1979-1982); Eddie and Judy Simon (1979-1982); Margaret Ellis O’Neal (1981-1984); Betty J. Kandt (1982-2018); Judith Peterson (1994-2009); Donna Cross (2002-2005); Eileen M. Black (2002-2020); and Robert and Carol Haller (2012-2024). However, research did not identify additional biographical or professional information

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CONTINUATION SHEET Trinomial
on these individuals, and it does not appear that they made significant contributions to our past. Therefore, 9320 Earl Street is not eligible under NRHP Criterion B or CRHR Criterion 2.

According to original building permits from the property’s construction in 1963, the architect was Stan Ring. The contractor is listed as the complex’s original owner, Walter G. Kurz (City of La Mesa Permits #18686 and #19147). Research identified a Stan Ring who, in 1984, owned Taylor Paper Tubes Company, which produced cardboard tubes (Hardy 1984: 34). According to a newspaper article about the business, Ring "started looking for a new source of income after deciding to get out of the real estate business" (Hardy 1984: 34). Research did identify additional information on Ring’s career, any memberships in professional architecture organizations, or additional architectural projects. As such, it appears unlikely that Ring was a master architect. According to the 1963 San Diego directory, Kurz’s profession was listed as a contractor (Ancestry.com).

However, research did not identify additional biographical or professional information on Kurz, nor did it identify additional projects constructed by Kurz. He does not appear to be a master builder or contractor.

The subject property appears to have been constructed through already well-documented and common construction techniques and methods and does not appear to possess high artistic values by articulating a particular concept of design to the extent that it expresses an aesthetic ideal. The last portion of Criterion C refers to a district, and this property does not contribute to the significance of a potential or existing historic district. Overall, 9320 Earl Street lacks sufficient design and construction value to meet NRHP Criterion C or CRHR Criterion 3.

Criterion D/4: [Properties] that have yielded, or may be likely to yield, information important in prehistory or history.

Under NRHP Criterion D and CRHR Criterion 4, 9320 Earl Street is not significant as a source, or likely source, of important historical information, nor does it appear likely to yield important information about historic construction methods, materials, or technologies. This technology is well understood through contemporary trade journals and scientific monographs. As such, the subject property lacks significance under NRHP Criterion D and CRHR Criterion 4.

City of La Mesa Evaluation
A cultural resource may be recommended for designation as a landmark or historic district, if it meets one or more of the following criteria:

A. It exemplifies or reflects special elements of the City's cultural, social, economic, political, aesthetic, engineering, or architectural history.

As discussed under NRHP/CRHR Criteria A/1, the subject property does not exemplify or reflect special elements of the City’s cultural, social, economic, political, aesthetic, engineering, or architectural history. It is a multi-family residential condominium complex constructed in 1963 during a period of rapid residential development throughout La Mesa. As such, the subject property is recommended not eligible under City of La Mesa Criteria A.

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*Recorded by Ahmanson, Dudek *Date February 12, 2024  Continuation  Update DPR 523L (9/2013) *Required information
State of California - The Resources Agency Primary#
DEPARTMENT OF PARKS AND RECREATION HRI #
CONTINUATION SHEET Trinomial
B. It is identified with persons or events significant in local, state, or national history.

C. It embodies distinctive characteristics of a style, type, period, or method of construction, or is a valuable example of the use of indigenous materials or craftsmanship.

As discussed under NRHP/CRHR Criteria C/3, the subject property is a common Ranch style single-family residence. It is constructed of already well-documented materials and techniques and is not a valuable example of the use of indigenous materials or craftsmanship. As such, the subject property is recommended not eligible under City of La Mesa Criteria C.

D. It is representative of the notable work of an acclaimed builder, designer, or architect.

E. It is identified with a person or persons or groups who significantly contributed to the culture and development of the City.

F. It embodies elements of outstanding attention to architectural design, detail, materials or craftsmanship.

As discussed under NRHP/CRHR Criteria C/3, the subject property does not embody elements of outstanding attention to architectural design, detail, materials, or craftsmanship. It is a ubiquitous, stylistically undifferentiated 1960s multi-family condominium complex constructed with already well documented materials. As such, the subject property is recommended not eligible under City of La Mesa Criteria F.

G. It is an archeological or paleontological site which has the potential of yielding information of scientific value.

As discussed under NRHP/CRHR Criteria 3, a geographically definable area possessing a concentration of associated buildings or sites is most applicable to districts. While the subject property is located in a neighborhood of single and multifamily residences constructed in the same time period , there are many such neighborhoods throughout La Mesa and research did not identify this neighborhood as having significant historical associations. As such, the subject property is recommended not eligible under City of La Mesa Criteria H.

Integrity Considerations

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*Recorded by Ahmanson, Dudek *Date February 12, 2024  Continuation  Update DPR 523L (9/2013) *Required information
State of California - The Resources Agency Primary#
DEPARTMENT OF PARKS AND RECREATION HRI #
CONTINUATION SHEET Trinomial
Because 9320 Earl Street lacks sufficient significance to meet any of the criteria for listing in the NRHP, CRHR, or as a City of La Mesa Historic Landmark, an integrity analysis was considered immaterial. To be eligible for listing in either register, a resource must first meet one or more of the significance criteria outlined above before a determination can be made as to whether the resource retains its historic character and can convey its significance.

Summary of Evaluation Findings
The subject property was evaluated in consideration of NRHP, CRHR, and City of La Mesa criteria and integrity requirements.

City of La Mesa Building Permits. 2024. Permit files. Received February 27, 2024.

City of La Mesa. 2012. City of La Mesa General Plan: Historic Preservation Element. https://www.cityoflamesa.us/DocumentCenter/View/6201/07LaMesaGPHistoricPreservation-CD?bidId=.

Hardy, Roger. 1984. "In the Center of Things: County Firm Busy Making Paper Tubes." February 19, 1984.

Newspapers.com: Ventura County Star (Ventura, California). Page 34.

Morgan, W. 2004. The Abrams Guide to American House Styles. New York City, New York: Harry N Abrams Inc.

Accessed February 5, 2024. https://www.historicaerials.com/viewer.

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*Recorded by Ahmanson, Dudek *Date February 12, 2024  Continuation  Update DPR 523L (9/2013) *Required information
State of California - The Resources Agency Primary#
DEPARTMENT OF PARKS AND RECREATION HRI #
CONTINUATION SHEET Trinomial
NETR. 2024b. “Historic Aerials Online.” Historic Topography Maps: 1893, 1897, 1901, 1903, 1909, 1916, 1930, 1941, 1942, 1947, 1955, 1956, 1959, 1964, 1969, 1975, 1976, 1978, 1986, 2001, 2012, 2015, 2018, and 2021. Accessed February 5, 2024. https://www.historicaerials.com/viewer.

ParcelQuest. 2024. Accessed March 4, 2024. https://pqweb.parcelquest.com/#home.

U.S. Department of the Interior (USDOI). 2002. “National Register Bulletin 15: How to Apply the National Register Criteria for Evaluation.” National Park Service, Cultural Resources. Accessed December 2023. https://www.nps.gov/subjects/nationalregister/upload/NRB-15_web508.pdf.

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Appendix C
Preparer’s Qualifications

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1 Katie Ahmanson, MHC

ARCHITECTURAL HISTORIAN
Katie Ahmanson (KAY-tee AH-mun-son; she/her) is an architectural historian with 3 years’ experience in the field of architectural history and heritage conservation. She has experience with Historic-Cultural Monument and National Register of Historic Places (NRHP) nominations, historic context statements, building descriptions, and California Department of Parks and Recreation (DPR) 523 forms. Ms. Ahmanson has worked with environmental compliance documentation in support of projects that fall under the California Environmental Quality Act (CEQA)/National Environmental Policy Act, and Sections 106 and 110 of the National Historic Preservation Act.

Project Experience
2021 Lincoln Avenue Department of Parks and Recreation Form, Action Day Schools, San José, California. Dudek was retained by the Action Day Schools to evaluate the property located at 2021 Lincoln Avenue in the City of San José, California (subject property) for eligibility for the NRHP, the California Register of Historical Resources (CRHR), and as a City of San José Landmark. As an architectural historian, coauthored a DPR 523 form documenting the history of the subject property and evaluating it for eligibility under all applicable criteria. Wrote building descriptions and significance evaluations, and completed archival research. (2023) Atascadero Armory Department of Parks and Recreation Form, Department of General Services, Atascadero, California. Dudek was retained by the Department of General Services to evaluate the Atascadero Armory located at 6105 Olmeda Avenue in the City of Atascadero in San Luis Obispo County, California (subject property) for eligibility for the NRHP, the CRHR, and as a California Historical Landmark. As an architectural historian, coauthored a DPR 523 form documenting the history of the subject property and evaluating it for eligibility under all applicable criteria. Completed the property survey, wrote building descriptions and significance evaluations, and completed archival research. (2023)
915 F Avenue Historic Resource Evaluation Report, City of Coronado, California. Dudek was retained by the City of Coronado to evaluate the property located at 915 F Avenue (Assessor’s Parcel Number [APN]: 537-322-03) for historical significance under City of Coronado designation criteria and integrity requirements. The evaluation involved research and development of an occupancy timeline, supplemental research on occupants and building development, survey of the property, a description of the property, and completion of a historical resource evaluation in consideration of City of Coronado designation criteria and integrity requirements. As an architectural historian, coauthored the report, wrote significance evaluations, and completed archival research. (2023) Mesa Verde Specific Plan Built Environment Inventory and Evaluation Report, Mesa Verde Owners, LLC, Calimesa, California. Dudek was retained by Mesa Verde Owners, LLC to complete a built environment inventory and evaluation report (BEIER) for the proposed Mesa Verde Specific Plan 2023 Project, which is an Amendment to the Mesa Verde Estates Specific Plan (SPA 13-01) that was previously adopted in 2007 and subsequently amended in Education
University of Southern
California School of
Architecture
MA, Heritage
Conservation, 2022
Claremont McKenna
College
BA, Art History, 2019

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2 2017. The purpose of the report is to determine if the project would impact any historical resources pursuant to CEQA. As an architectural historian, coauthored the report, wrote significance evaluations and building descriptions, and completed archival research. (2023)
South Bay Area Plan Project Historic Context Statement, unincorporated Los Angeles County, California. Dudek was retained by the County of Los Angeles Department of Regional Planning to prepare a Historic Context Statement (HCS) for the South Bay Area Plan (SBAP) project. The HCS is one component of the larger SBAP project that addresses the following seven unincorporated communities of the County: Alondra Park/El Camino Village, Del Aire/Wiseburn, Hawthorne Island, La Rambla, Lennox, West Carson, and Westfield/Academy Hills (SBAP communities). Collectively, these SBAP communities reside within the South Bay Planning Area, which is one of the 11 Planning Areas identified in the County General Plan. The purpose of the HCS is to inform and enhance the larger SBAP project as it relates to historical resources within the SBAP communities, including the preparation of goals, policies, and implementation programs. As an architectural historian, surveyed the area and completed archival research for the report. (2023)
721 J Avenue Historic Resource Evaluation Report, City of Coronado, California. Dudek was retained by the City of Coronado to evaluate the property located at 721 J Avenue (APN: 537-052-04-00) for historical significance under City of Coronado designation criteria and integrity requirements. The evaluation involved research and development of an occupancy timeline, supplemental research on occupants and building development, survey of the property, a description of the property, and completion of a historical resource evaluation in consideration of City of Coronado designation criteria and integrity requirements. As an architectural historian, coauthored the report, wrote significance evaluations, completed archival research, and surveyed the property. (2023) 1118 Flora Avenue Historic Resource Evaluation Report, City of Coronado, California. Dudek was retained by the City of Coronado to evaluate the property located at 1118 Flora Avenue (APN: 537-540-04-00) for historical significance under City of Coronado designation criteria and integrity requirements. The evaluation involved research and development of an occupancy timeline, supplemental research on occupants and building development, survey of the property, a description of the property, and completion of a historical resource evaluation in consideration of City of Coronado designation criteria and integrity requirements. As an architectural historian, coauthored the report, wrote significance evaluations, completed archival research, and surveyed the property. (2023)
Marysville High School Track and Fields Improvement Project Built Environment Inventory and Evaluation Report, Marysville Joint Unified School District, Marysville, California. Dudek was retained by the Marysville Joint Unified School District to complete a BEIER for compliance with CEQA for the Marysville High School Track and Fields Improvement Project on the Marysville High School campus located in the City of Marysville, Yuba County, California. The project would replace the existing track and sports field facilities at the high school. The purpose of the report is to determine if the project would impact any historical resources pursuant to CEQA. As an architectural historian, coauthored the report, wrote significance evaluations and building descriptions, and completed archival research. (2023)
873 G Avenue Historic Resource Evaluation Report, City of Coronado, California. Dudek was retained by the City of Coronado to evaluate the property located at 873 G Avenue (APN: 537-231-13-00) for historical significance under City of Coronado designation criteria and integrity requirements. The evaluation involved research and development of an occupancy timeline, supplemental research on occupants and building development, survey of the property, a description of the property, and completion of a historical resource evaluation in consideration of

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1 Claire Cancilla, MSHP

ARCHITECTURAL HISTORIAN
Claire Cancilla (KLAIR Kan-sil-uh; she/her) is an Architectural Historian with 5 years’ professional and academic experience that encompasses a wide variety of project types in varied geographic locations, including Los Angeles, Laguna Beach, Agoura Hills, Baldwin Park, Glendale, Pasadena, South Pasadena, Poway, Riverside, San Diego, Rialto, Vista, Sequoia National Park, New York City, and Venice, Italy. She has completed historic significance evaluations and impacts analyses in consideration of the National Register of Historic Places (NRHP), California Register of Historic Resources (CRHR), and local designation criteria for single-family residences, commercial properties, educational institutions, warehouse and industrial properties, and municipal facilities.

Additional project experience includes writing national register and local register nominations, conducting historic archival research, performing conditions assessments and reconnaissance surveys, conducting CEQA impacts analyses, preparing environmental impact report (EIR) sections, and conducting design reviews under the Secretary of the Interior’s Standards. She meets the Secretary of the Interior’s Professional Qualification Standards for Architectural History.

Dudek Project Experience
Skylight Replacement Project, Los Angeles Harbor Department (LAHD), San Pedro, California. Dudek is included on the Los Angeles Harbor Department’s list of on-call historic consultants and was retained by the LAHD to conduct a Secretary of the Interior Standards conformance review for a skylight replacement project of four buildings located at the Port of Los Angles. This work involves updating previously completed Department of Parks and Recreation 523 forms for three properties and preparing new DPR forms for one property. This work further involves the review of schematics and plans for proposed skylight replacements for conformance with the Secretary of the Interior’s Standards for Rehabilitation. Ms. Cancilla is the lead author of this ongoing work. (2023-present).

Berths 58-60 Secretary of the Interior Standards Conformance Review, Los Angeles Harbor Department (LAHD), San Pedro, California. Dudek was retained by the LAHD to conduct a Secretary of the Interior Standards conformance review for proposed alterations in anticipation of an adaptive reuse of Berths 58-60, a historical resource and former transit shed constructed in 1913 located on City Dock No. 1 at the Port of Los Angeles. Ms.

Cancilla conducted the site visit with the property tenants, project architect, and LAHD representatives; reviewed plans and schematics; and conducted an analysis of all proposed alterations to ensure Rehabilitation. (2022).

Siemens Industrial Mixed Use Expansion Project, City of Pomona, Pomona, California. Dudek was retained by the City of Pomona to prepare a Built Environment Inventory and Evaluation Report for a proposed industrial expansion of a Siemens electrical manufacturing facility and warehouse. The existing warehouse and manufacturing facility was constructed in 1973. Ms. Cancilla was the lead author of the report and conducted the fieldwork; research; and evaluation of the property for significance at the national, state, and local level. (2022).

Education
Columbia University
Graduate School of
Architecture, Planning,
and Preservation,
MSHP, Historic
Preservation, 2020
Occidental College
BA, History, 2016

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2 Vista Old Taylor Project, TTLC Management Inc., Vista, California. Dudek was retained by TTLC Management Inc. to prepare a Built Environment Inventory and Evaluation Report for a proposed residential development project. This work involved the recordation and evaluation of two single-family residential properties constructed in the 1940s and 1950s. Ms. Cancilla is the lead author of the BEIR, conducted fieldwork, and prepared the property significance evaluations under national, state, and local eligibility criteria (2022 – 2023).

Alice / Willow Avenue Warehouse Project, Patriot Development Partners, Rialto, California. Dudek was retained by Patriot Development Partners to conduct a Built Environment Inventory and Evaluation Report for a 6.19-acre site in the city of Rialto, California. Ms. Cancilla was the lead author of the BEIR, which involved research on and evaluation of six light industrial and commercial buildings over 45 years of age. (2022 – 2023).

Kaiser Baldwin Park Medical Center Project, Top Commercial Realty, Baldwin Park California. Dudek was retained to complete a Built Environment Inventory and Evaluation Report for a proposed project involving the development of the Kaiser Baldwin Park Medical Center. Ms. Cancilla was the lead author of the Built Environment Inventory and Evaluation Report for a 1970s vernacular commercial building. (2022).

Arlington Avenue Historic Resources Technical Report, Foulger Pratt, Riverside, California. Dudek was retained to complete a Historic Resources Technical Report on a Mid-Century Modern former Sears Department Store in the city of Riverside, California for a proposed redevelopment. Ms. Cancilla contributed to the significance evaluation and historic contexts for the technical report. (2022).

Oak Knoll Road, Poway, San Diego County, California. Dudek was retained to complete a historical resources evaluation for a residential development project in the City of Poway. The Project proposes the development of the

10.72-acre property into a residential development within an existing residential neighborhood. As an architectural historian, Ms. Cancilla contributed to the significance evaluation and historic contexts for the technical report. (2022)
2121 Orange Street Built Environment Inventory and Evaluation Report, Alhambra, California. Dudek was retained to complete a Built Environment Inventory and Evaluation Report for a proposed self-storage redevelopment in the City of Alhambra. The Project proposes the demolition of an existing office building and warehouse in 1974. As an architectural historian, Ms. Cancilla conducted the fieldwork, research, and evaluation for the property. (2022). 4235 State Street Historic Resources Technical Report, Santa Barbara County, California. Dudek was retained to prepare a Historic Resources Technical Report evaluating the significance of a prefabricated gas station constructed in 1953 in unincorporated Santa Barbara County for a proposed redevelopment. As an architectural historian, Ms. Cancilla conducted the fieldwork, research, and evaluation for the property. (2022).

Los Angeles County Metro Area Plan Project, Los Angeles County, California. Dudek was retained by the County of Los Angeles Department of Regional Planning to prepare a Historic Context Statement (HCS) in support of the Metro Area Plan (MAP) project. The goal of the HCS component of the project is to inform, enhance, and streamline the larger MAP project as it pertains to historical resources. The communities included within the MAP HCS include East Los Angeles, East Rancho Dominguez, Florence–Firestone, Walnut Park, West Athens– Westmont, West Rancho Dominguez–Victoria, and Willowbrook. The HCS documents the development history of the communities from the rancho period to the present; identifies important themes, events, and patterns of development; and describes the different property types, styles, builders, and architects associated with these important periods and themes. The document will also provide registration requirements and recommendations for future study/action by the County of Los Angeles to facilitate and streamline the historic preservation program.

Responsibilities include report section preparation and archival research. (2022)

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1 Patricia Ambacher

SENIOR ARCHITECTURAL HISTORIAN
Patricia Ambacher (she/her) is a senior architectural historian with 21 years’ professional experience specializing in historic preservation, Section 106 of the National Historic Preservation Act (NHPA), the National Environmental Policy Act (NEPA)/California Environmental Quality Act (CEQA), and cultural resources management.

Ms. Ambacher has prepared a range of technical documents including historic resources evaluation reports, finding of effects, built environment treatment plans, and historic property management plans, as well as Historic American Buildings Survey (HABS), Historic American Engineering Record (HAER), and Historic American Landscapes Survey (HALS) documentation. Her clients include public and private entities seeking expertise in cultural resources and historic preservation.

Relevant Previous Experience
Development
Various Privately Owned Properties Historic Resources Evaluations, City of Davis, California. The City of Davis has a historic preservation ordinance that requires evaluation of the historical significance of properties that are more than 50 years old if an applicant proposes to demolish the building.

Prepared the historic resources evaluation reports and evaluated properties using the criteria for the City of Davis’ two local registration programs, the National Register of Historic Places (NRHP), and the California Register of Historical Resources (CRHR) for three separate projects. Also presented the findings before the Davis Historical Resources Management Commission. For one of the properties, the analysis was met with opposition, but ultimately the city accepted the documentation and all the projects moved forward. (2009–2010) Historic Resource Evaluations for the Stanislaus County Courthouse, Stanislaus County Hall of Records, Modesto Bee Building, and Team Modesto Properties, California Administrative Office of Courts, Modesto, California. The California Administrative Office of Courts (AOC) was seeking a new location for the Stanislaus County Courthouse and required the existing eight buildings at those sites be evaluated for compliance with California Public Resources Code (PRC) Section 5024.5. Because of state budgetary cuts, the project did not move forward for execution, but the analysis was completed and submitted to the State Historic Preservation Officer (SHPO) as documentation for the future when budgetary costs allow for the project. As the lead architectural historian, oversaw research, historic context development, and the evaluation. (2011) Historic Resource Evaluation Report for a CVS Pharmacy Store, Armstrong Development Properties Inc., Sacramento, California. The project was to develop the parcel that contained a former mid-twentieth century little league baseball field. The site required evaluation against the criteria for the NRHP, the CRHR, and the city’s local register to comply with CEQA and the local historic preservation ordinance. The findings were accepted by the Education
California State University,
Sacramento
MA, History– Emphasis in
Public History, 2002
BA, History, 1993
Professional Affiliations
California Preservation
Foundation

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2 preservation director and the project was constructed. As the lead architectural historian, conducted archival research, fieldwork, and the evaluations. (2011)
Cultural Resources Investigation of the Clarion Hotel, Pacifica Companies, Sacramento, California. Pacifica Companies bought the former Clarion Hotel. To comply with local ordinances and CEQA, the hotel needed to be evaluated for its potential eligibility for the NRHP, CRHR, and the Sacramento Register of Historical and Cultural Resources. The hotel was the early work of the prominent, locally recognized architectural firm of Dreyfuss & Blackford and landscape architect Robert Deering. The findings were accepted by the City of Sacramento and the report was eventually used for CEQA compliance. As the lead historian, conducted archival research and prepared an evaluation for the three registration programs. (2013) Glenn County Superior Courthouse Initial Study/Mitigated Negative Declaration, California Administrative Office of Courts, Willows, California. The California AOC proposed to purchase and demolish a residence built in 1913 to construct a new parking lot for the Superior Court. The residence needed to be evaluated for the CRHR to comply with CEQA. The findings were accepted and the project was completed. As the lead architectural historian, prepared an inventory and evaluation of the residence for its eligibility for the CRHR. Conducted research and wrote the report verifying that the building had no historical significance. (2013) 800 Indiana Preservation Alternatives Analysis, Avalon Bay, San Francisco, California. The proposed project would have demolished a large warehouse building to construct a new housing development. The project was subject to CEQA, and the City and County of San Francisco requires project applicants prepare preservation alternatives as part of project alternatives analyzed in an environmental impact report (EIR). As lead architectural historian, worked with the applicant’s architects to develop preservation alternatives that could incorporate the historic resource in the design and prepared the technical documentation outlining how the preservation alternatives could meet the Secretary of the Interior’s Standards for Rehabilitation. This analysis was used later in the CEQA documentation. (2013–2014)
CVS Pharmacy Store Historic Resource Evaluation, Armstrong Development Properties Inc., Sacramento, California. The project was for the demolition of an existing grocery store, which was historically a Safeway grocery store designed by a known architect who designed several grocery stores, schools, and other public buildings during the mid-twentieth century in Sacramento and the greater region. The building required evaluation against the criteria for the NRHP, the CRHR, and the city’s local register to comply with CEQA and the local historic preservation ordinance. The project met with resistance from a local historic preservation group. The findings were accepted by the preservation director and the new CVS was built. As the lead architectural historian, conducted archival research, fieldwork, and evaluation. (2014) Sacramento Commons EIR, Kennedy Wilson, Sacramento, California. The project proposed to demolish a midcentury modern garden apartment complex determined eligible for the NRHP by the Keeper of the Register. That determination made the property a historical resource for the purposes of CEQA. As lead architectural historian, provided peer review of a sub-consultant’s historical resources evaluation of the apartment complex. Because the environmental assessment concluded that the project would have a significant and unavoidable impact to the historic resource, mitigation measures were crafted for the project, which included preparing a Level II HABS for the resource. Also conducted archival research pertaining to the architectural plans at the University of California, Berkeley, Environmental Design Archives and prepared the work plan for the creation of the documentation. (2014–2015)

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Appendix D
Cultural Resources Inventory Report

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July 26, 2024 15823
Laura Traffenstedt
City of La Mesa
8130 Allison Avenue
City of La Mesa, California 91941

Subject: Cultural Resources Phase I Inventory Report for the 9407 Jericho Road Project, City of La Mesa, California
Dear Ms. Traffenstedt:

This letter documents the cultural resources Phase I inventory conducted by Dudek for the 9407 Jericho Road Project (Project), located in the City of La Mesa, California (Figure 1). The proposed Project would redevelop the existing site with up to 73 three-story residential townhomes. The proposed townhomes would range in size from approximately 1,200 – 1,800 square feet with 2-4 bedrooms. The City of La Mesa (City) is the lead agency responsible for compliance with the California Environmental Quality Act (CEQA). In accordance with CEQA, Dudek performed a Phase I cultural resources inventory for the entire Project area. The Project area consists of approximately 3.49-acre area covering one parcel (APN 486-670-18) (Figure 2).

CEQA refers to sequential stages of cultural resources investigation, including Inventory, Evaluation, and Mitigation.

Phase I (Inventory), Phase II (Evaluation), and Phase III (Mitigation) are vernacular terms used in the cultural resources industry. For the purposes of this report, Phase I is defined as an Inventory and includes archival research for archaeological resources and Tribal Cultural Resources (TCRs), pedestrian surveys, and other inventory methods.

Dudek conducted a records search of the California Historical Resources Information System (CHRIS) at the South Coastal Information Center (SCIC), located on the campus of San Diego State University for the Project area and a one-mile search buffer. The SCIC records search indicates that no cultural resources intersect the Project area.

Additionally, 34 previous cultural resources have been recorded within the one-mile search buffer of the Project area.

Dudek requested a search of the Sacred Lands File from the NAHC on January 31, 2024. A response letter was received via email from the NAHC on February 15, 2024, stating that the results were positive. The NAHC recommended Dudek contact the Native American Representatives who may have information about cultural resources within the Project area. Dudek sent outreach letters on February 19, 2024 and to date, no responses have been received.

Dudek conducted an intensive level cultural resources pedestrian survey for the Project area and did not identify any cultural resources within the Project area. The Project area contains three buildings including the Calvary church

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TO: MS. TRAFFENSTEDT
SUBJECT: CULTURAL RESOURCES PHASE I INVENTORY REPORT FOR THE 9407 JERICHO RESIDENTIAL ROAD PROJECT

CITY OF LA MESA, CALIFORNIA
15823 2
JULY 2024
with connected sanctuary on its east elevation constructed in 1959 and two educational buildings constructed in 1973, located north of the church. These structures are considered built environment resources and are addressed in a separate built environment report (Ahmanson 2024).

Due to the presence of historic age buildings on the Project area, there is a moderate sensitivity for identifying unanticipated historic age subsurface archaeological deposits during Project implementation. Dudek recommends cultural resources monitoring, consisting of a qualified archaeological monitor and Kumeyaay Native American monitor during all initial ground disturbing activities within native soils (below the fill sediment). Monitoring can be reduced or terminated should no discoveries are made or if documentation is provided which demonstrates that ground-disturbing activities will be occurring in sediments with no potential for cultural resources to be present. If human remains are found, the County Coroner shall be immediately notified of the discovery in accordance with Section 7050.5 of the California Health and Safety Code. 3 Project Description and Location
The Project is located at 9407 Jericho Road, in the City of La Mesa (APN 486-670-18). The Project area falls within Section 16 of Township 16 South, Range 1 West of the La Mesa and El Cajon, California 7.5-minute Quadrangles (Figure 1). The current Project area has been previously disturbed and is currently developed with the existing Calvary Chapel, parking lot, turf area, playground, and associated church facilities/structures. The Project area is located in an urban area of the City surrounded on all sides by existing development, including single-family homes to the north and east, and multi-family developments to the south and the west.

The Project consists of demolition of existing commercial uses on-site (Calvary Church), and redevelopment 73 three-story townhomes on the 3.49-acre site (Figure 1). The townhomes would range in size from approximately 1,200 – 1,800 square feet and 2-4 bedrooms. The Project would include two garage spaces per unit plus approximately five (5) guest spaces.
2 Regulatory Framework

2.1 The California Register of Historic Resources (Public Resources Code section 5020 et seq.)
Under CEQA, the term “historical resource” includes but is not limited to “any object, building, structure, site, area, place, record, or manuscript which is historically or archaeologically significant, or is significant in the architectural, engineering, scientific, economic, agricultural, educational, social, political, military, or cultural annals of California” (California Public Resources Code section 5020.1(j)). In 1992, the California legislature established CRHR “to be used by state and local agencies, private groups, and citizens to identify the state’s historical resources and to indicate what properties are to be protected, to the extent prudent and feasible, from substantial adverse change” (California Public Resources Code section 5024.1(a)). A resource is eligible for listing in the CRHR if the State Historical Resources Commission determines that it is a significant resource and that it meets any of the following National Register of Historic Places (NRHP) criteria:

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TO: MS. TRAFFENSTEDT
SUBJECT: CULTURAL RESOURCES PHASE I INVENTORY REPORT FOR THE 9407 JERICHO RESIDENTIAL ROAD PROJECT

CITY OF LA MESA, CALIFORNIA
15823 3
JULY 2024
▪ Associated with events that have made a significant contribution to the broad patterns of California’s history and cultural heritage.
▪ Associated with the lives of persons important in our past. ▪ Embodies the distinctive characteristics of a type, period, region, or method of construction, or represents the work of an important creative individual, or possesses high artistic values. ▪ Has yielded, or may be likely to yield, information important in prehistory or history. (California Public Resources Code section 5024.1I.) Resources less than 50 years old are not considered for listing in the CRHR, but may be considered if it can be demonstrated that sufficient time has passed to understand the historical importance of the resource (see 14 CCR, section 4852(d)(2)).

The CRHR protects cultural resources by requiring evaluations of the significance of prehistoric and historic resources. The criteria for the CRHR are nearly identical to those for the NRHP, and properties listed or formally designated as eligible for listing on the NRHP are automatically listed on the CRHR, as are the state landmarks and points of interest. The CRHR also includes properties designated under local ordinances or identified through local historical resource surveys. The State Historic Preservation Officer maintains the CRHR.

2.2 Native American Historic Cultural Sites (California Public Resources Code section 5097 et seq.)
State law addresses the disposition of Native American burials in archaeological sites and protects such remains from disturbance, vandalism, or inadvertent destruction; establishes procedures to be implemented if Native American skeletal remains are discovered during construction of a project; and establishes the NRHC to resolve disputes regarding the disposition of such remains. In addition, the Native American Historic Resource Protection Act makes it a misdemeanor punishable by up to 1 year in jail to deface or destroy an Indian historic or cultural site that is listed or may be eligible for listing in the CRHR.

2.3 California Environmental Quality Act
As described further below, the following CEQA statutes and CEQA Guidelines are of relevance to the analysis of archaeological and historic resources:

California Public Resources Code section 21083.2(g): Defines “unique archaeological resource.” California Public Resources Code section 21084.1 and CEQA Guidelines section 15064.5(a): Define historical resources. In addition, CEQA Guidelines section 15064.5(b) defines the phrase “substantial adverse change in the significance of an historical resource;” it also defines the circumstances when a project would materially impair the significance of a historical resource.

California Public Resources Code section 5097.98 and CEQA Guidelines section 15064.5I: Set forth standards and steps to be employed following the accidental discovery of human remains in any location other than a dedicated ceremony.

California Public Resources Code sections 21083.2(b)-(c) and CEQA Guidelines section 15126.4: Provide information regarding the mitigation framework for archaeological and historic resources, including options of preservation-in-place mitigation measures; preservation-in-place is the preferred manner of mitigating

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CITY OF LA MESA, CALIFORNIA
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JULY 2024
impacts to significant archaeological sites because it maintains the relationship between artifacts and the archaeological context, and may also help avoid conflict with religious or cultural values of groups associated with the archaeological site(s).

Under CEQA, a project may have a significant effect on the environment if it may cause “a substantial adverse change in the significance of an historical resource” (California Public Resources Code section 21084.1; CEQA Guidelines section 15064.5(b)). If a site is either listed or eligible for listing in the CRHR, or if it is included in a local register of historic resources, or identified as significant in a historical resources survey (meeting the requirements of California Public Resources Code section 5024.1(q)), it is a “historical resource” and is presumed to be historically or culturally significant for purposes of CEQA (California Public Resources Code section 21084.1; CEQA Guidelines section 15064.5(a)). The lead agency is not precluded from determining that a resource is a historical resource even if it does not fall within this presumption (California Public Resources Code section 21084.1; CEQA Guidelines section 15064.5(a)).

A “substantial adverse change in the significance of an historical resource” reflecting a significant effect under CEQA means “physical demolition, destruction, relocation, or alteration of the resource or its immediate surroundings such that the significance of an historical resource would be materially impaired” (CEQA Guidelines section 15064.5(b)(1); California Public Resources Code section 5020.1(q)). In turn, the significance of a historical resource is materially impaired when a project:

Demolishes or materially alters in an adverse manner those physical characteristics of an historical resource that convey its historical significance and that justify its inclusion in, or eligibility for, inclusion in the California Register; or
Demolishes or materially alters in an adverse manner those physical characteristics that account for its inclusion in a local register of historical resources pursuant to section 5020.1(k) of the Public Resources Code or its identification in an historical resources survey meeting the requirements of section 5024.1(g) of the Public Resources Code, unless the public agency reviewing the effects of the project establishes by a preponderance of evidence that the resource is not historically or culturally significant; or Demolishes or materially alters in an adverse manner those physical characteristics of a historical resource that convey its historical significance and that justify its eligibility for inclusion in the California Register as determined by a lead agency for purposes of CEQA.

See Section 2.7, below for a discussion of the CEQA guidelines for determining significance and mitigating impacts to unique archaeological resources.

2.4 California Health and Safety Code Section 7050.5 and Public Resources Code Section 5097.98
CEQA Guidelines Section 15064.5 assigns special importance to human remains and specifies procedures to be used when Native American remains are discovered. As described below, these procedures are detailed in California Health and Safety Code Section 7050.5 and Public Resources Code Section 5097.98.

California law protects Native American burials, skeletal remains, and associated grave goods, regardless of their antiquity, and provides for the sensitive treatment and disposition of those remains. Health and Safety Code Section 7050.5 requires that if human remains are discovered in any place other than a dedicated cemetery, no

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CITY OF LA MESA, CALIFORNIA
15823 5
JULY 2024
further disturbance or excavation of the site or nearby area reasonably suspected to contain human remains shall occur until the County coroner has examined the remains (California Health and Safety Code Section 7050.5[b]).

If the coroner determines or has reason to believe the remains are those of a Native American, the coroner must contact the NAHC within 24 hours (California Health and Safety Code Section 7050.5[c]). In accordance with California Public Resources Code Section 5097.98(a), the NAHC will notify the Most Likely Descendant (MLD). With the permission of the landowner, the MLD may inspect the site of discovery. Within 48 hours of being granted access to the site, the MLD may recommend means of treatment or disposition, with appropriate dignity, of the human remains and associated grave goods.

2.5 Assembly Bill 52
California Assembly Bill 52, which took effect July 1, 2015, establishes a consultation process between California Native American Tribes and lead agencies in order to address tribal concerns regarding project impacts and mitigation to “tribal cultural resources” (TCR). Public Resources Code section 21074(a) defines TCRs and states that a project that has the potential to cause a substantial adverse change to a TCR is a project that may have an adverse effect on the environment. A TCR is defined as a site, feature, place, cultural landscape, sacred place, and object with cultural value to a California Native American tribe that is either:
listed or eligible for listing in the CRHR or a local register of historical resources, or determined by a lead agency to be a TCR.

2.6 Senate Bill 18
California Senate Bill 18 (SB 18), which took effect on March 1, 2005, requires local (city and county) governments to consult with California Native American tribes identified by the Native American Heritage Commission (NAHC) for the purpose of protecting, and/or mitigating impacts to cultural places in creating or amending general plans, including specific plans (Government Code section 65352.3).

2.7 Guidelines for Determining Significance
According to CEQA (§15064.5b), a project with an effect that may cause a substantial adverse change in the significance of an historical resource is a project that may have a significant effect on the environment. CEQA defines a substantial adverse change:

Substantial adverse change in the significance of an historical resource means physical demolition, destruction, relocation, or alteration of the resource or its immediate surroundings such that the significance of an historical resource would be materially impaired.

The significance of an historical resource is materially impaired when a project:
• Demolishes or materially alters in an adverse manner those physical characteristics of an historical resource that convey its historical significance and that justify its inclusion in, or eligibility for inclusion in, the CRHR; or

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CITY OF LA MESA, CALIFORNIA
15823 6
JULY 2024
• Demolishes or materially alters in an adverse manner those physical characteristics that account for its inclusion in a local register of historical resources pursuant to section 5020.1(k) of the Public Resources Code or its identification in an historical resources survey meeting the requirements of section 5024.1(g) of the Public Resources Code, unless the public agency reviewing the effects of the project establishes by a preponderance of evidence that the resource is not historically or culturally significant; or • Demolishes or materially alters in an adverse manner those physical characteristics of an historical resource that convey its historical significance and that justify its eligibility for inclusion in the CRHR as determined by a lead agency for purposes of CEQA.

Section 15064.5I of CEQA applies to effects on archaeological sites and contains the following additional provisions regarding archaeological sites:
• When a project will impact an archaeological site, a lead agency shall first determine whether the site is an historical resource, as defined in subsection (a).
• If a lead agency determines that the archaeological site is a historical resource, it shall refer to the provisions of Section 21084.1 of the Public Resources Code, and this section, Section 15126.4 of the Guidelines, and the limits contained in Section 21083.2 of the Public Resources Code do not apply. • If an archaeological site does not meet the criteria defined in subsection (a), but does meet the definition of a unique archaeological resource in Section 21083.2 of the Public Resources Code, the site shall be treated in accordance with the provisions of section 21083.2. The time and cost limitations described in Public Resources Code Section 21083.2 (c–f) do not apply to surveys and site evaluation activities intended to determine whether the project location contains unique archaeological resources. • If an archaeological resource is neither a unique archaeological nor a historical resource, the effects of the project on those resources shall not be considered a significant effect on the environment. It shall be sufficient that both the resource and the effect on it are noted in the Initial Study or Environmental Impact Report (EIR), if one is prepared to address impacts on other resources, but they need not be considered further in the CEQA process.

Section 15064.5(d) and I contain additional provisions regarding human remains. Regarding Native American human remains, paragraph (d) provides:

When an initial study identifies the existence of, or the probable likelihood of, Native American human remains within the project, a lead agency shall work with the appropriate Native Americans as identified by the Native American Heritage Commission as provided in Public Resources Code SS5097.98. The applicant may develop an agreement for treating or disposing of, with appropriate dignity, the human remains and any items associated with Native American burials with the appropriate Native Americans as identified by the Native American Heritage Commission. Action implementing such an agreement is exempt from:

1. The general prohibition on disinterring, disturbing, or removing human remains from any location other than a dedicated cemetery (Health and Safety Code Section 7050.5); and

2. The requirement of CEQA and the Coastal Act.

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CITY OF LA MESA, CALIFORNIA
15823 7
JULY 2024
Under CEQA, an EIR is required to evaluate any impacts on unique archaeological resources (California Public Resources Code section 21083.2.) A “unique archaeological resource” is defined as:
[A]n archaeological artifact, object, or site about which it can be clearly demonstrated that, without merely adding to the current body of knowledge, there is a high probability that it meets any of the following criteria:

1. Contains information needed to answer important scientific research questions and that there is a demonstrable public interest in that information.

2. Has a special and particular quality such as being the oldest of its type or the best available example of its type.

3. Is directly associated with a scientifically recognized important prehistoric or historic event or person. (California Public Resources Code section 21083.2(g)). An impact to a non-unique archaeological resource is not considered a significant environmental impact and such non-unique resources need not be further addressed in the EIR (Public Resources Code section 21083.2(a); CEQA Guidelines section 15064.5(c)(4)).

As stated above, CEQA contains rules for mitigation of “unique archaeological resources.” For example, “[i]f it can be demonstrated that a project will cause damage to a unique archaeological resource, the lead agency may require reasonable efforts to be made to permit any or all of these resources to be preserved in place or left in an undisturbed state. Examples of that treatment, in no order of preference, may include, but are not limited to, any of the following:

1. Planning construction to avoid archaeological sites.

2. Deeding archaeological sites into permanent conservation easements.

3. Capping or covering archaeological sites with a layer of soil before building on the sites.

4. Planning parks, greenspace, or other open space to incorporate archaeological sites.” (Pub. Resources Code section 21083.2(b)(1)-(4).)
Public Resources Code section 21083.2(d) states that “[e]xcavation as mitigation shall be restricted to those parts of the unique archaeological resource that would be damaged or destroyed by the project. Excavation as mitigation shall not be required for a unique archaeological resource if the lead agency determines that testing or studies already completed have adequately recovered the scientifically consequential information from and about the resource, if this determination is documented in the environmental impact report.” The rules for mitigating impacts to archaeological resources to qualify as “historic resources” are slightly different.

According to CEQA Guidelines section 15126.4(b), “[p]ublic agencies should, whenever feasible, seek to avoid damaging effects on any historic resource of an archaeological nature. The following factors shall be considered and discussed in an EIR for a project involving such an archaeological site:

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CITY OF LA MESA, CALIFORNIA
15823 8
JULY 2024
A. Preservation in place is the preferred manner of mitigating impacts to archaeological sites. Preservation in place maintains the relationship between artifacts and the archaeological context. Preservation may also avoid conflict with religious or cultural values of groups associated with the site.

B. Preservation in place may be accomplished by, but is not limited to, the following:

1. Planning construction to avoid archaeological sites;

2. Incorporation of sites within parks, greenspace, or other open space;

3. Covering the archaeological sites with a layer of chemically stable soil before building tennis courts, parking lots, or similar facilities on the site[; and]

4. Deeding the site into a permanent conservation easement.

Thus, although section 21083.2 of the Public Resources Code, in addressing “unique archaeological sites,” provides for specific mitigation options “in no order of preference,” CEQA Guidelines section 15126.4(b), in addressing “historical resources of an archaeological nature,” provides that “[p]reservation in place is the preferred manner of mitigating impacts to archaeological sites.”
Under CEQA, “[w]hen data recovery through excavation is the only feasible mitigation,” the lead agency may cause to be prepared and adopt a “data recovery plan,” prior to any excavation being undertaken. The data recovery plan must make “provision for adequately recovering the scientifically consequential information from and about the historic resource.” (CEQA Guidelines section 15126.4(b)(3)(C).) The data recovery plan also “must be deposited with the California Historical Resources Regional Information Center.” (Ibid.) Further, “[i]f an artifact must be removed during project excavation or testing, curation may be an appropriate mitigation.” (Ibid.) However, “[d]ata recovery shall not be required for an historical resource if the lead agency determines that testing or studies already completed have adequately recovered the scientifically consequential information from and about the archaeological or historic resource, provided that determination is documented in the EIR and that the studies are deposited with the California Historical Resources Regional Information Center.” (CEQA Guidelines section 15126.4(b)(3)(D).)

2.8 City of La Mesa General Plan
The City of La Mesa adopted a General Plan in 2012 that documents the goals, objectives, and policies that guides the City’s development and vision until 2030. The General Plan contains an Historic Preservation element, which was developed to:

Provide a long-range blueprint to guide the process of historic preservation in La Mesa through 2030, including the identification and treatment of historical and cultural resources, to support program management and decision-making, and to integrate preservation planning into the comprehensive urban planning and development process. The Historic Preservation Element provides Goals, Objectives, and Policies intended to sustain and improve the quality of La Mesa’s built and cultural environment, and to

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CITY OF LA MESA, CALIFORNIA
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JULY 2024
promote awareness and enthusiasm for the unique identity and heritage that La Mesa possesses (City of La Mesa 2012: HP-12 – HP 14).

The Historic Preservation Element is reproduced below (City of La Mesa 2012: HP-12 – HP 14):

Goal HP-1: Broadened recognition by La Mesans that the spirit and direction of the City’s growth is substantially reflected in its historic past.

Objective HP-1.1: Broaden recognition and awareness of the processes and features of the La Mesa Historic Preservation Program.

Policy HP-1.1.1: Form partnerships and share information between the City and preservation advocacy organizations to foster and support local public history projects.

Policy HP-1.1.2: Inform citizens and project applicants of preservation regulations as part of the development review process.

Objective HP-1.2: Update and maintain the La Mesa Historic Resources Inventory to identify the potential eligibility of properties built in the historic-era.

Policy HP-1.2.1: Implement a phased Historical Resource Survey program that accounts for all locations in the City and all building stock that achieves the historic era through time.

Policy HP-1.2.2: Establish guidelines for identifying eligible properties in the Modern Period (circa 1935-1975) throughout the City.

Goal HP-2: Safeguarded heritage by preserving those elements that reflect our cultural, social, economic, and architectural history so that community residents will have a foundation upon which to measure and direct physical change.

Objective HP-2.1: Encourage retention and reuse of significant and / or historic-era building stock to safeguard heritage, promote material conservation, and provide for sustainable and green building techniques at historic-era properties.

Policy HP-2.1.1: Develop guidelines on the architectural styles of La Mesa with corresponding character-defining features to serve as a threshold for local Landmark designation eligibility.

Policy HP-2.1.2: Incorporate sustainability principles and green building practices at historic-era buildings and sites in a sensitive and complementary manner.

Policy HP-2.1.3: Update the Resource Management Guidelines to account for The Secretary of the Interior’s Standards for Rehabilitation & Illustrated Guidelines on Sustainability for Rehabilitating Historic Buildings.

Goal HP-3: A strengthened local economic base with stabilized and improved property values through the identification and protection of individual properties and historic districts.

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CITY OF LA MESA, CALIFORNIA
15823 10 JULY 2024
Objective HP-3.1: Advance traditional town planning techniques and urban design models consistent with periods of development in La Mesa that will strengthen livability and pedestrian opportunities.

Policy HP-3.1.1: Establish a historic context on the residential development history of La Mesa to identify potential historic districts based on residential subdivision tract map boundaries and relative to the greater architectural and planning history of community building.

Policy HP-3.1.2: Establish Conservation Overlay Zones in Historic Districts to ensure appropriate use, density, scale, massing, and physical arrangement of existing and new buildings within Historic District boundaries.
3 Methods

3.1 Records Search
Dudek conducted a records search of the California Historical Resources Information System (CHRIS) at the South Coastal Information Center (SCIC), located on the campus of San Diego State University for the Project area and a one-mile search buffer on February 7, 2024. The records search results indicates that 41 previous cultural resources studies have been conducted within one-mile radius of the Project area; none of which intersect the Project area. The entirety of the Project area has not been previously studied. The full records search results is attached as Confidential Appendix A.

The SCIC records search did not identify any cultural resources within the Project area. The records search did identify 34 cultural resources within the one-mile buffer outside of the Project area (Confidential Appendix A). Of the total 34 resources identified in the one-mile radius buffer, 33 are historic built environment resources (buildings), one is a prehistoric artifact scatter, and one is an undocumented resource. Additionally, 23 historic addresses were identified within the one-mile radius buffer outside of the Project area; none of which intersect the Project area. The full records search results is attached as Confidential Appendix A.

3.2 Archival Research
In addition to the SCIC records search, Dudek conducted an on-line review of historic aerial photographs of the Project area and general vicinity, to help determine the possible development and land use of the Project area in the past. Historic aerial photographs of the Project area were available from 1953 to 2020 (NETR 2024). The historic aerial from 1953 reveals that the Project area was undeveloped. It appears that Amaya Drive had been developed southeast of the Project area by 1953. The 1964 aerial imagery reveals the Calvary church, parking lot, and Jericho Road as developed within the Project area, while construction activity for residential and commercial properties is seen in the adjacent parcels. The historic aerial from 1960 does not show any substantial changes to the Project area, however, there is a steady increase in residential and commercial properties in the adjacent parcels. The 1968 historic aerial does not show any substantial changes to the Project area, however, there was development of residential properties along Broadmoore Place immediately north of the Project area. The historic aerial from 1978 does not show any substantial changes to the Project area, however, there was development of residential properties immediately southwest of the Project area. The historic aerial from 1980 does not show any substantial changes to the Project area or general vicinity. There are no changes to the Project area on the 1981

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CITY OF LA MESA, CALIFORNIA
15823 11 JULY 2024
to 1999. By 2000 the historic aerials reveal the parking lot within the Project area had been expanded. There are no substantial changes to the Project area between 2002 to 2014. The historic aerial from 2019 reveals there is redevelopment of the asphalt court within the northwestern portion of the Project area. A review of the historic aerials reveal that the Project area is currently used for commercial purposes. The Project area contains three buildings including the Calvary church with connected sanctuary on its east elevation constructed in 1959 and two educational buildings constructed in 1973, located north of the church. The parking lot located within the center portion of the Project area has been expanded in the 1980s. These structures are considered built environment resources and are addressed in a separate built environment report (Ahmanson 2024).

Historic topographic (topo) maps of the Project area were reviewed (earliest map available is 1893). The 1969 topo map shows the Calvary church as developed within the Project area. By 2015, the topo map shows the Calvary church as a commercial building.

3.3 Geotechnical Review
LGC Geotechnical, Inc. prepared a geotechnical subsurface due diligence evaluation for the Project area (Boratynec and Petersen 2023). The study details the results of five small-diameter hollow stem borings. The borings were drilled to depths of approximately 6.5 to 14 feet below existing grade. The Project area is underlain by the Mission Valley Formation and the Mission Valley Formation is underlain by older artificial fill that was placed during the development of the existing development (Boratynec and Petersen 2023). The depth of the artificial fill ranges from approximately

2.5 to 7.5 feet below existing grade. It was also noted that borings are only representative of the location and time where they were placed, and subsurface conditions may vary outside of the boring locations (Boratynec and Petersen 2023).

3.4 Native American Heritage Commission Sacred Lands File Search and Tribal Correspondence
Dudek requested a search of the Sacred Lands Files (SLF) from the Native American Heritage Commission (NAHC) on January 31, 2024. The SLF consists of a database of known Native American resources. These resources may not be included in the SCIC database. A response letter was received via email from the NAHC on February 15, 2024, stating the results were positive, but did not provide details on what the resource(s) are or where they are located in relation to the Project area (Appendix B). The NAHC additionally provided a list of Native American tribes and individuals/organizations with traditional geographic associations that might have knowledge of cultural resources in this area. Outreach letters were mailed on February 19, 2024 to all Native American group representatives included on the NAHC contact list (Appendix B). These letters attempted to solicit additional information relating to Native American resources that may be impacted by the Project. No responses have been received to date. Any responses to the letters will be forwarded to the City and included in subsequent drafts of this report. The NAHC correspondence is included in Appendix B.

In compliance with Assembly Bill 52 and Senate Bill 18, the City, as lead agency, is responsible for conducting government to government consultation with pertinent tribal entities.

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CITY OF LA MESA, CALIFORNIA
15823 12 JULY 2024

3.5 Survey Results
Dudek archaeologist Javier Hernandez conducted an intensive level pedestrian survey of the Project area on February 23, 2024. Red Tail Environmental Inc., Native American monitor Kenny Teter participated in the pedestrian survey. All survey work was conducted employing standard archaeological procedures and techniques consistent with the Secretary of the Interior Standards. Fifteen-meter interval survey transects were conducted where possible for the Project area. Where transects were not feasible (such as areas where the ground surface was obscured by development, pavement, and landscaping) transects were not utilized. Instead, a mixed approach (opportunistic survey) was utilized, selectively examining terraces and exposed sediments where possible. The ground surface was examined for prehistoric artifacts (e.g., flaked stone tools, tool-making debris, stone milling tools, ceramics, fire-affected rock), soil discoloration that might indicate the presence of a cultural midden, soil depressions, features indicative of the current or former presence of structures or buildings (e.g., standing exterior walls, post holes, foundations), and historic artifacts (e.g., metal, glass, ceramics, building materials). Ground disturbances such as burrows, cut banks, and drainages were also visually inspected for exposed subsurface materials.

The entire Project area has been disturbed, as evidenced by the presence of one existing building (Calvary Church) and paved surfaces (parking lot and asphalt playground/game court) (Figure 3). Approximately 75% of the Project area is developed, while the remainder of the Project area consists of a primarily landscaped open area (Figure 4).

Ground visibility in the Project area was poor (0-25%) and visibility was obscured by the existing building, paved surfaces, and landscaped grass. The soil consisted of a medium brown sand with moderate content (25-50%) of modern shell fragments. No cultural resources were identified within the Project area.

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SUBJECT: CULTURAL RESOURCES PHASE I INVENTORY REPORT FOR THE 9407 JERICHO RESIDENTIAL ROAD PROJECT

CITY OF LA MESA, CALIFORNIA
15823 13 JULY 2024
4 Summary and Management Considerations

4.1 Archaeological Recommendations
Dudek’s Phase I cultural resources inventory of the Project indicates that there is moderate sensitivity for identifying intact subsurface historic age archaeological deposits during Project implementation. The SCIC records search results indicates that no cultural resources have been identified within the Project area. However, the records search identified 34 cultural resources within one-mile of the Project area. The archival research review also revealed that the entire Project area has not been previously studied.

The pedestrian survey did not identify any cultural resources within the Project area. However, there are three historic age (over 45 years old) buildings located within Project area including one Calvary Church and two educational buildings. These structures are considered built environment resources and are addressed in a separate built environment report (Ahmanson 2024).

Dudek recommends that a qualified archaeologist and Kumeyaay Native American monitor to be present during all initial ground disturbing activities to confirm there are no subsurface deposits. If disturbed sediments (e.g., fill) or other sediments and formations are identified that do not have the potential to contain cultural resources, then monitoring may be reduced or terminated.

Unanticipated Discovery of Human Remains
In accordance with Section 7050.5 of the California Health and Safety Code, if human remains are found, the County Coroner shall be notified within 24 hours of the discovery. No further excavation or disturbance of the site or any nearby area reasonably suspected to overlie adjacent remains shall occur until the County Coroner has determined, within two working days of notification of the discovery, the appropriate treatment and disposition of the human remains. If the remains are determined to be Native American, the Coroner shall notify the NAHC in Sacramento within 24 hours. In accordance with California Public Resources Code, Section 5097.98, the NAHC must immediately notify those persons it believes to be the most likely descended (MLD) from the deceased Native American. The MLD shall complete their inspection within 48 hours of being granted access to the site. The designated Native American representative would then determine, in consultation with the property owner, the disposition of the human remains
Should you have any questions relating to this report and its findings, please do not hesitate to contact me at 760.846.5874 or [email protected] and Angela Pham at 760.479.4855 or [email protected].

Respectfully Submitted,
—————————— ——————————
Makayla Murillo, B.A., Angela Pham, M.A., RPA
Archaeologist Archaeologist

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CITY OF LA MESA, CALIFORNIA
15823 14 JULY 2024
Att.: Figure 1, Project Location
Figure 2, Project Area Map
Figure 3. Overview of the Calvary Church and parking lot, facing northeast.

Figure 4. Overview of the eastern portion of Project area, view facing southwest.

Confidential Appendix A, SCIC Records Search Results
Appendix B, NAHC and Tribal Correspondence
cc: Vanessa Scheidel, Micah Hale, Dudek
5 References
Boratynec and Petersen. 2023. Preliminary Geotechnical Subsurface Dude Diligence Evaluation for the Proposed Residential Development, 9407 Jericho Road, La Mesa, California. Prepared for Meritage Homes.

City of La Mesa General Plan. 2012. Accessed February 20, 2024. https://www.cityoflamesa.us/DocumentCenter/View/6201/07LaMesaGPHistoricPreservation-CD?bidId= NETR (National Environmental Title Research). 2024. 9407 Jericho Road, La Mesa, California. Accessed February 2024. http://www.historicaerials.com/.

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Project Location
Jericho Road Project
SOURCE: USGS 7.5-Minute Series La Mesa and El Cajon Quadrangles Township 16 S / Range 1 W / Section 16
Date: 2/28/2024 - Last saved by: ckubacki - Path: Z:\Projects\j1582301\MAPDOC\DOCUMENT\Cultural\Figure1_ProjectLocation.mxd 0 2,000 1,000 Feet
Project Boundary
FIGURE 1
1:24,000
0 600300 Meters
Pacific Ocean
15 5
805
8 215
78 94
79 76
67 74
86 52
75 56
163
111
209
905
54 11
125
125
78 54
78 Mexico
Riverside County
San Diego
Poway
Chula Vista
Carlsbad
Oceanside
Escondido
Vista
Santee
San Marcos
Encinitas
El Cajon
Coronado
Imperial Beach
Solana Beach
Del Mar
Project Site

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Date: 2/28/2024 - Last saved by: ckubacki - Path: Z:\Projects\j1582301\MAPDOC\DOCUMENT\Cultural\Figure2_ProjectAreaMap.mxd Lakeview Dr
Broadmoor Pl
Jericho Rd
Broadmoor Dr
Amaya Dr
Project Area Map
Jericho Road Project
SOURCE: SanGIS 2023, Open Street Map 2019
0 10050 Feet
Project Boundary
FIGURE 2

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FIGURES
15823
APRIL 2024

Figure 3. Overview of the Calvary Church and parking lot, facing northeast.

Figure 4. Overview of the eastern portion of Project area, view facing southwest.

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Confidential Appendix A
SCIC Records Search Results

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Appendix B
NAHC and Tribal Correspondence

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Sacred Lands File & Native American Contacts List Request Native American Heritage Commission
1550 Harbor Blvd, Suite 100
West Sacramento, CA 95691
916-373-3710
916-373-5471 – Fax
[email protected]
Information Below is Required for a Sacred Lands File Search Project: ______________________________________________________________________ County:______________________________________________________________________ USGS Quadrangle Name:_______________________________________________________ Township:__________ Range:__________ Section(s):__________ Company/Firm/Agency:_________________________________________________________ Street Address:________________________________________________________________ City:______________________________________________ Zip:______________________ Phone:_____________________________________________
Fax:_______________________________________________
Email:_____________________________________________
Project Description:
9407 Jericho Road Project San Diego County
Dudek 605 Third Street
Encinitas
92024 760.479.4827 760.632.0164
MLC Holdings, Inc. is proposing to redevelop the existing site at 9407 Jericho Road, in the City of La Mesa, California. The project would include up to 73 three story townhomes on a 3.49 acre site. The townhomes would range in size from approximately 1,200 - 1,800 square feet and 2 - 4 bedrooms.
[email protected] & [email protected] 7.5-Minute Series La Mesa and El Cajon Quadrangle 16S 1W 16

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LA MESA

EL CAJON EL CAJON

LA MESA
Records Search Map
Jericho Road Project
SOURCE: USGS 7.5-Minute Series La Mesa and El Cajon Quadrangles Township 16 S / Range 1 W / Section 16
Date: 1/29/2024 - Last saved by: ckubacki - Path: Z:\Projects\j1582301\MAPDOC\DOCUMENT\Cultural\RecordsSearchMap.mxd 0 2,000 1,000 Feet
Project Boundary
One-Mile Buffer
1:24,000
0 600300 Meters Page 1634 of 2604

Page 1635 of 2604 ends

STATE OF CALIFORNIA Gavin Newsom, Governor

NATIVE AMERICAN HERITAGE COMMISSION

Page 1 of 1 ends

February 15, 2024
Makayla Murillo
Dudek
Via Email to: [email protected]
Re: 9407 Jericho Road Project, San Diego County
Dear Ms. Murillo:

A record search of the Native American Heritage Commission (NAHC) Sacred Lands File (SLF) was completed for the information submitted for the above referenced project. The results were positive. Please contact the Barona Group of the Capitan Grande and the Viejas Band of Kumeyaay Indians on the attached list for information. Please also contact the Kumeyaay Cultural Repatriation Committee via phone at (760) 803-5694 for information. Please note that tribes do not always record their sacred sites in the SLF, nor are they required to do so. A SLF search is not a substitute for consultation with tribes that are traditionally and culturally affiliated with a project’s geographic area. Other sources of cultural resources should also be contacted for information regarding known and recorded sites, such as the appropriate regional California Historical Research Information System (CHRIS) archaeological Information Center for the presence of recorded archaeological sites.

Attached is a list of Native American tribes who may also have knowledge of cultural resources in the project area. This list should provide a starting place in locating areas of potential adverse impact within the proposed project area. Please contact all of those listed; if they cannot supply information, they may recommend others with specific knowledge. By contacting all those listed, your organization will be better able to respond to claims of failure to consult with the appropriate tribe. If a response has not been received within two weeks of notification, the Commission requests that you follow-up with a telephone call or email to ensure that the project information has been received.

If you receive notification of change of addresses and phone numbers from tribes, please notify the NAHC. With your assistance, we can assure that our lists contain current information.

If you have any questions or need additional information, please contact me at my email address: [email protected]
Sincerely,
Murphy Donahue
Cultural Resources Analyst

Attachment

CHAIRPERSON
Reginald Pagaling
Chumash

VICE-CHAIRPERSON
Buffy McQuillen
Yokayo Pomo, Yuki,
Nomlaki

SECRETARY
Sara Dutschke
Miwok

PARLIAMENTARIAN
Wayne Nelson
Luiseño

COMMISSIONER
Isaac Bojorquez
Ohlone-Costanoan

COMMISSIONER
Stanley Rodriguez
Kumeyaay

COMMISSIONER
Laurena Bolden
Serrano

COMMISSIONER
Reid Milanovich
Cahuilla

COMMISSIONER
Vacant

EXECUTIVE SECRETARY
Raymond C.

Hitchcock
Miwok, Nisenan

NAHC HEADQUARTERS
1550 Harbor Boulevard
Suite 100
West Sacramento,
California 95691
(916) 373-3710
[email protected]
NAHC ca gov

Page 1636 of 2604 ends

County Tribe Name Fed (F)
Non-Fed (N)
Contact Person Contact Address Phone # Fax # Email Address Cultural Affiliation Barona Group of the Capitan Grande F Art Bunce, Attorney (760) 489-0329 [email protected] Diegueno Campo Band of Diegueno Mission Indians F Ralph Goff, Chairperson 36190 Church Road, Suite 1 Campo, CA, 91906
(619) 478-9046 (619) 478-5818 [email protected] Diegueno Ewiiaapaayp Band of Kumeyaay Indians F Michael Garcia, Vice Chairperson 4054 Willows Road Alpine, CA, 91901
(619) 933-2200 (619) 445-9126 [email protected] Diegueno Ewiiaapaayp Band of Kumeyaay Indians F Robert Pinto, Chairperson 4054 Willows Road Alpine, CA, 91901
(619) 368-4382 (619) 445-9126 [email protected] Diegueno Iipay Nation of Santa Ysabel F Clint Linton, Director of Cultural Resources
P.O. Box 507
Santa Ysabel, CA, 92070
(760) 803-5694 [email protected] Diegueno Inaja-Cosmit Band of Indians F Rebecca Osuna, Chairperson 2005 S. Escondido Blvd.

Escondido, CA, 92025
(760) 737-7628 (760) 747-8568 Diegueno
Jamul Indian Village F Lisa Cumper, Tribal Historic
Preservation Officer
P.O. Box 612
Jamul, CA, 91935
(619) 669-4855 [email protected] Diegueno
Jamul Indian Village F Erica Pinto, Chairperson P.O. Box 612 Jamul, CA, 91935
(619) 669-4785 (619) 669-4817 [email protected] Diegueno Kwaaymii Laguna Band of Mission Indians N Carmen Lucas, Chairperson P.O. Box 775 Pine Valley, CA, 91962
(619) 709-4207 Kwaaymii
Diegueno
La Posta Band of Diegueno Mission
Indians
F Gwendolyn Parada, Chairperson 8 Crestwood Road
Boulevard, CA, 91905
(619) 478-2113 (619) 478-2125 [email protected] Diegueno Manzanita Band of Kumeyaay Nation F Angela Elliott Santos, Chairperson
P.O. Box 1302
Boulevard, CA, 91905
(619) 766-4930 (619) 766-4957 Diegueno
Mesa Grande Band of Diegueno Mission
Indians
F Michael Linton, Chairperson P.O Box 270
Santa Ysabel, CA, 92070
(760) 782-3818 (760) 782-9092 [email protected] Diegueno San Pasqual Band of Diegueno Mission
Indians
F Allen Lawson, Chairperson P.O. Box 365
Valley Center, CA, 92082
(760) 749-3200 (760) 749-3876 [email protected] Diegueno San Pasqual Band of Diegueno Mission
Indians
F John Flores, Environmental
Coordinator
P. O. Box 365
Valley Center, CA, 92082
(760) 749-3200 (760) 749-3876 [email protected] Diegueno Sycuan Band of the Kumeyaay Nation F Bernice Paipa, Cultural Resource Specialist
Sycuan Cultural Center: 910
Willow Glen Drive
El Cajon, CA, 92019
(619) 445-6917 [email protected] Kumeyaay
Sycuan Band of the Kumeyaay Nation F Cody Martinez, Chairman Sycuan Tribal Office: 1 Kwaaypaay Court
El Cajon, CA, 92019
(619) 445-2613 [email protected] Kumeyaay
Viejas Band of Kumeyaay Indians F Ray Teran, Resource
Management Director
1 Viejas Grade Road
Alpine, CA, 91901
(619) 659-2312 [email protected] Kumeyaay
Viejas Band of Kumeyaay Indians F Ernest Pingleton, THPO 1 Viejas Grade Road Alpine, CA, 91901
(619) 445-3810 [email protected] Kumeyaay
Native American Heritage Commission
Native American Contact List
San Diego County
2/15/2024
Counties Last Updated
San Diego Imperial,San Diego 7/25/2023
Imperial,Orange,Riverside,San Diego
Imperial,Orange,Riverside,San Diego
Imperial,Orange,Riverside,San Diego
Imperial,San Diego 11/30/2023
Imperial,San Diego
Imperial,San Diego 9/5/2018
Imperial,San Diego
Imperial,San Diego 6/20/2023
Imperial,Orange,Riverside,San Diego
Imperial,Orange,Riverside,San Diego
Imperial,Orange,Riverside,San Diego
Imperial,San Diego
Imperial,San Diego 8/16/2016
Imperial,San Diego 8/7/2023
This list is current only as of the date of this document. Distribution of this list does not relieve any person of statutory responsibility as defined in Section 7050.5 of the Health and Safety Code, Section 5097.94 of the Public Resource Section 5097.98 of the Public Resources Code.

This list is only applicable for contacting local Native Americans with regard to cultural resources assessment for the proposed 9407 Jericho Road Project, San Diego County.

Record: PROJ-2024-000798
Report Type: List of Tribes
Counties: San Diego
NAHC Group: All
Imperial,San Diego 8/7/2023
Imperial,San Diego 6/29/2023
Imperial,San Diego 6/29/2023
02/15/2024 08:40 AM
1 of 1

Page 1637 of 2604 ends

February 19, 2024 15823
Ms. Lisa Cumper, THPO
Jamul Indian Village
P.O. Box 612
Jamul, CA 91935
Subject: Information Request for the 9407 Jericho Road Residential Project, City of La Mesa, San Diego County, California
Dear Ms. Cumper,
The 9407 Jericho Road Residential Project (project) is located at 9407 Jericho Road, in the City of La Mesa, San Diego County, California (Figure 1). The project plans to redevelop the existing site and construct 73 three-story townhomes on a 3.49-acre site. This project falls on Section 16, Township 16 South, Range 1 West in the La Mesa and El Cajon U.S. Geological Survey (USGS) 7.5-minute Quadrangles.

As part of the cultural resources study prepared for the proposed project, Dudek contacted the Native American Heritage Commission (NAHC) conducted a Sacred Lands file (SLF) search and a list of Native American individuals and/or tribal organizations who may have knowledge of cultural resources in or near the proposed project area.

The NAHC emailed a response on February 15, 2024, which stated that the SLF search identified the presence of Native American cultural resources in the immediate project area.

Please note that this letter does not constitute Assembly Bill (AB) 52 notification or initiation of consultation.

Tribes that wish to be notified of projects for the purposes of consultation must contact the lead agency, City of La Mesa (City) in writing (pursuant to Public Resources Code Section 21080.3.1 (b)).

If you have any information or concerns pertaining to such information, please contact me by phone or email.

Respectfully,
_________________
Makayla Murillo, B.A.

Archaeologist
DUDEK
Phone: (760) 846-5874
Email: [email protected]
Attachments: Figure 1. Records Search Map

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February 19, 2024 15823
Mr. John Flores, Environmental Coordinator
San Pasqual Band of Diegueno Mission Indians
P.O. Box 365
Valley Center, CA 92082
Subject: Information Request for the 9407 Jericho Road Residential Project, City of La Mesa, San Diego County, California
Dear Mr. Flores,
The 9407 Jericho Road Residential Project (project) is located at 9407 Jericho Road, in the City of La Mesa, San Diego County, California (Figure 1). The project plans to redevelop the existing site and construct 73 three-story townhomes on a 3.49-acre site. This project falls on Section 16, Township 16 South, Range 1 West in the La Mesa and El Cajon U.S. Geological Survey (USGS) 7.5-minute Quadrangles.

The NAHC emailed a response on February 15, 2024, which stated that the SLF search identified the presence of Native American cultural resources in the immediate project area.

Please note that this letter does not constitute Assembly Bill (AB) 52 notification or initiation of consultation.

Tribes that wish to be notified of projects for the purposes of consultation must contact the lead agency, City of La Mesa (City) in writing (pursuant to Public Resources Code Section 21080.3.1 (b)).

If you have any information or concerns pertaining to such information, please contact me by phone or email.

Respectfully,
_________________
Makayla Murillo, B.A.

Archaeologist
DUDEK
Phone: (760) 846-5874
Email: [email protected]
Attachments: Figure 1. Records Search Map

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February 19, 2024 15823
Mr. Michael Garcia, Vice Chairperson
Ewiiaapaayp Band of Kumeyaay Indians
4054 Willows Road
Alpine, CA 91901
Subject: Information Request for the 9407 Jericho Road Residential Project, City of La Mesa, San Diego County, California
Dear Mr. Garcia,
The 9407 Jericho Road Residential Project (project) is located at 9407 Jericho Road, in the City of La Mesa, San Diego County, California (Figure 1). The project plans to redevelop the existing site and construct 73 three-story townhomes on a 3.49-acre site. This project falls on Section 16, Township 16 South, Range 1 West in the La Mesa and El Cajon U.S. Geological Survey (USGS) 7.5-minute Quadrangles.

The NAHC emailed a response on February 15, 2024, which stated that the SLF search identified the presence of Native American cultural resources in the immediate project area.

Please note that this letter does not constitute Assembly Bill (AB) 52 notification or initiation of consultation.

Tribes that wish to be notified of projects for the purposes of consultation must contact the lead agency, City of La Mesa (City) in writing (pursuant to Public Resources Code Section 21080.3.1 (b)).

If you have any information or concerns pertaining to such information, please contact me by phone or email.

Respectfully,
_________________
Makayla Murillo, B.A.

Archaeologist
DUDEK
Phone: (760) 846-5874
Email: [email protected]
Attachments: Figure 1. Records Search Map

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Page 1649 of 2604 ends

February 19, 2024 15823
Mr. Ralph Goff, Chairperson
Campo Band of Diegueno Mission Indians
36190 Church Road, Suite 1
Campo, CA 91906
Subject: Information Request for the 9407 Jericho Road Residential Project, City of La Mesa, San Diego County, California
Dear Mr. Goff,
The 9407 Jericho Road Residential Project (project) is located at 9407 Jericho Road, in the City of La Mesa, San Diego County, California (Figure 1). The project plans to redevelop the existing site and construct 73 three-story townhomes on a 3.49-acre site. This project falls on Section 16, Township 16 South, Range 1 West in the La Mesa and El Cajon U.S. Geological Survey (USGS) 7.5-minute Quadrangles.

The NAHC emailed a response on February 15, 2024, which stated that the SLF search identified the presence of Native American cultural resources in the immediate project area.

Please note that this letter does not constitute Assembly Bill (AB) 52 notification or initiation of consultation.

Tribes that wish to be notified of projects for the purposes of consultation must contact the lead agency, City of La Mesa (City) in writing (pursuant to Public Resources Code Section 21080.3.1 (b)).

If you have any information or concerns pertaining to such information, please contact me by phone or email.

Respectfully,
_________________
Makayla Murillo, B.A.

Archaeologist
DUDEK
Phone: (760) 846-5874
Email: [email protected]
Attachments: Figure 1. Records Search Map

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February 19, 2024 15823
Mr. Allen E. Lawson, Chairperson
San Pasqual Band of Diegueno Mission Indians
P.O. Box 365
Valley Center, CA 92082
Subject: Information Request for the 9407 Jericho Road Residential Project, City of La Mesa, San Diego County, California
Dear Mr. Lawson,
The 9407 Jericho Road Residential Project (project) is located at 9407 Jericho Road, in the City of La Mesa, San Diego County, California (Figure 1). The project plans to redevelop the existing site and construct 73 three-story townhomes on a 3.49-acre site. This project falls on Section 16, Township 16 South, Range 1 West in the La Mesa and El Cajon U.S. Geological Survey (USGS) 7.5-minute Quadrangles.

The NAHC emailed a response on February 15, 2024, which stated that the SLF search identified the presence of Native American cultural resources in the immediate project area.

Please note that this letter does not constitute Assembly Bill (AB) 52 notification or initiation of consultation.

Tribes that wish to be notified of projects for the purposes of consultation must contact the lead agency, City of La Mesa (City) in writing (pursuant to Public Resources Code Section 21080.3.1 (b)).

If you have any information or concerns pertaining to such information, please contact me by phone or email.

Respectfully,
_________________
Makayla Murillo, B.A.

Archaeologist
DUDEK
Phone: (760) 846-5874
Email: [email protected]
Attachments: Figure 1. Records Search Map

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February 19, 2024 15823
Mr. Clint Linton, Director of Cultural Resources
Ipay Nation of Santa Ysabel
P.O. Box 507
Santa Ysabel, CA 92070
Subject: Information Request for the 9407 Jericho Road Residential Project, City of La Mesa, San Diego County, California
Dear Mr. Linton,
The 9407 Jericho Road Residential Project (project) is located at 9407 Jericho Road, in the City of La Mesa, San Diego County, California (Figure 1). The project plans to redevelop the existing site and construct 73 three-story townhomes on a 3.49-acre site. This project falls on Section 16, Township 16 South, Range 1 West in the La Mesa and El Cajon U.S. Geological Survey (USGS) 7.5-minute Quadrangles.

The NAHC emailed a response on February 15, 2024, which stated that the SLF search identified the presence of Native American cultural resources in the immediate project area.

Please note that this letter does not constitute Assembly Bill (AB) 52 notification or initiation of consultation.

Tribes that wish to be notified of projects for the purposes of consultation must contact the lead agency, City of La Mesa (City) in writing (pursuant to Public Resources Code Section 21080.3.1 (b)).

If you have any information or concerns pertaining to such information, please contact me by phone or email.

Respectfully,
_________________
Makayla Murillo, B.A.

Archaeologist
DUDEK
Phone: (760) 846-5874
Email: [email protected]
Attachments: Figure 1. Records Search Map

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February 19, 2024 15823
Mr. Michael Linton, Chairperson
Mesa Grande Band of Dieguneo Mission Indians
P.O. Box 270
Santa Ysabel, CA 92070
Subject: Information Request for the 9407 Jericho Road Residential Project, City of La Mesa, San Diego County, California
Dear Mr. Linton,
The 9407 Jericho Road Residential Project (project) is located at 9407 Jericho Road, in the City of La Mesa, San Diego County, California (Figure 1). The project plans to redevelop the existing site and construct 73 three-story townhomes on a 3.49-acre site. This project falls on Section 16, Township 16 South, Range 1 West in the La Mesa and El Cajon U.S. Geological Survey (USGS) 7.5-minute Quadrangles.

The NAHC emailed a response on February 15, 2024, which stated that the SLF search identified the presence of Native American cultural resources in the immediate project area.

Please note that this letter does not constitute Assembly Bill (AB) 52 notification or initiation of consultation.

Tribes that wish to be notified of projects for the purposes of consultation must contact the lead agency, City of La Mesa (City) in writing (pursuant to Public Resources Code Section 21080.3.1 (b)).

If you have any information or concerns pertaining to such information, please contact me by phone or email.

Respectfully,
_________________
Makayla Murillo, B.A.

Archaeologist
DUDEK
Phone: (760) 846-5874
Email: [email protected]
Attachments: Figure 1. Records Search Map

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February 19, 2024 15823
Ms. Carmen Lucas,
Kwaaymii Laguna Band of Mission Indians
P.O. Box 775
Pine Valley, CA 91962
Subject: Information Request for the 9407 Jericho Road Residential Project, City of La Mesa, San Diego County, California
Dear Ms. Lucas,
The 9407 Jericho Road Residential Project (project) is located at 9407 Jericho Road, in the City of La Mesa, San Diego County, California (Figure 1). The project plans to redevelop the existing site and construct 73 three-story townhomes on a 3.49-acre site. This project falls on Section 16, Township 16 South, Range 1 West in the La Mesa and El Cajon U.S. Geological Survey (USGS) 7.5-minute Quadrangles.

The NAHC emailed a response on February 15, 2024, which stated that the SLF search identified the presence of Native American cultural resources in the immediate project area.

Please note that this letter does not constitute Assembly Bill (AB) 52 notification or initiation of consultation.

Tribes that wish to be notified of projects for the purposes of consultation must contact the lead agency, City of La Mesa (City) in writing (pursuant to Public Resources Code Section 21080.3.1 (b)).

If you have any information or concerns pertaining to such information, please contact me by phone or email.

Respectfully,
_________________
Makayla Murillo, B.A.

Archaeologist
DUDEK
Phone: (760) 846-5874
Email: [email protected]
Attachments: Figure 1. Records Search Map

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February 19, 2024 15823
Mr. Cody Martinez, Chairperson
Sycuan Band of the Kumeyaay Nation
1 Kwaaypaay Court
El Cajon, CA 92019
Subject: Information Request for the 9407 Jericho Road Residential Project, City of La Mesa, San Diego County, California
Dear Mr. Martinez,
The 9407 Jericho Road Residential Project (project) is located at 9407 Jericho Road, in the City of La Mesa, San Diego County, California (Figure 1). The project plans to redevelop the existing site and construct 73 three-story townhomes on a 3.49-acre site. This project falls on Section 16, Township 16 South, Range 1 West in the La Mesa and El Cajon U.S. Geological Survey (USGS) 7.5-minute Quadrangles.

The NAHC emailed a response on February 15, 2024, which stated that the SLF search identified the presence of Native American cultural resources in the immediate project area.

Please note that this letter does not constitute Assembly Bill (AB) 52 notification or initiation of consultation.

Tribes that wish to be notified of projects for the purposes of consultation must contact the lead agency, City of La Mesa (City) in writing (pursuant to Public Resources Code Section 21080.3.1 (b)).

If you have any information or concerns pertaining to such information, please contact me by phone or email.

Respectfully,
_________________
Makayla Murillo, B.A.

Archaeologist
DUDEK
Phone: (760) 846-5874
Email: [email protected]
Attachments: Figure 1. Records Search Map

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February 19, 2024 15823
Ms. Rebecca Osuna, Chairperson
Inaja-Cosmit Band of Indians
2005 S. Escondido Blvd.

Escondido, CA 92025
Subject: Information Request for the 9407 Jericho Road Residential Project, City of La Mesa, San Diego County, California
Dear Ms. Osuna,
The 9407 Jericho Road Residential Project (project) is located at 9407 Jericho Road, in the City of La Mesa, San Diego County, California (Figure 1). The project plans to redevelop the existing site and construct 73 three-story townhomes on a 3.49-acre site. This project falls on Section 16, Township 16 South, Range 1 West in the La Mesa and El Cajon U.S. Geological Survey (USGS) 7.5-minute Quadrangles.

The NAHC emailed a response on February 15, 2024, which stated that the SLF search identified the presence of Native American cultural resources in the immediate project area.

Please note that this letter does not constitute Assembly Bill (AB) 52 notification or initiation of consultation.

Tribes that wish to be notified of projects for the purposes of consultation must contact the lead agency, City of La Mesa (City) in writing (pursuant to Public Resources Code Section 21080.3.1 (b)).

If you have any information or concerns pertaining to such information, please contact me by phone or email.

Respectfully,
_________________
Makayla Murillo, B.A.

Archaeologist
DUDEK
Phone: (760) 846-5874
Email: [email protected]
Attachments: Figure 1. Records Search Map

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February 19, 2024 15823
Ms. Bernice Paipa, Vice Spokesperson
Kumeyaay Cultural Repatriation Committee
P.O. Box 63
Santa Ysabel, CA 92070
Subject: Information Request for the 9407 Jericho Road Residential Project, City of La Mesa, San Diego County, California
Dear Ms. Paipa,
The 9407 Jericho Road Residential Project (project) is located at 9407 Jericho Road, in the City of La Mesa, San Diego County, California (Figure 1). The project plans to redevelop the existing site and construct 73 three-story townhomes on a 3.49-acre site. This project falls on Section 16, Township 16 South, Range 1 West in the La Mesa and El Cajon U.S. Geological Survey (USGS) 7.5-minute Quadrangles.

The NAHC emailed a response on February 15, 2024, which stated that the SLF search identified the presence of Native American cultural resources in the immediate project area.

Please note that this letter does not constitute Assembly Bill (AB) 52 notification or initiation of consultation.

Tribes that wish to be notified of projects for the purposes of consultation must contact the lead agency, City of La Mesa (City) in writing (pursuant to Public Resources Code Section 21080.3.1 (b)).

If you have any information or concerns pertaining to such information, please contact me by phone or email.

Respectfully,
_________________
Makayla Murillo, B.A.

Archaeologist
DUDEK
Phone: (760) 846-5874
Email: [email protected]
Attachments: Figure 1. Records Search Map

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February 19, 2024 15823
Ms. Gwendolyn Parada, Chairperson
La Posta Band of Diegueno Mission Indians
8 Crestwood Rd.

Boulevard, CA 91905
Subject: Information Request for the 9407 Jericho Road Residential Project, City of La Mesa, San Diego County, California
Dear Ms. Parada,
The 9407 Jericho Road Residential Project (project) is located at 9407 Jericho Road, in the City of La Mesa, San Diego County, California (Figure 1). The project plans to redevelop the existing site and construct 73 three-story townhomes on a 3.49-acre site. This project falls on Section 16, Township 16 South, Range 1 West in the La Mesa and El Cajon U.S. Geological Survey (USGS) 7.5-minute Quadrangles.

The NAHC emailed a response on February 15, 2024, which stated that the SLF search identified the presence of Native American cultural resources in the immediate project area.

Please note that this letter does not constitute Assembly Bill (AB) 52 notification or initiation of consultation.

Tribes that wish to be notified of projects for the purposes of consultation must contact the lead agency, City of La Mesa (City) in writing (pursuant to Public Resources Code Section 21080.3.1 (b)).

If you have any information or concerns pertaining to such information, please contact me by phone or email.

Respectfully,
_________________
Makayla Murillo, B.A.

Archaeologist
DUDEK
Phone: (760) 846-5874
Email: [email protected]
Attachments: Figure 1. Records Search Map

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February 19, 2024 15823
Mr. Ernest Pingleton, Tribal Historic Officer
Viejas Band of Kumeyaay Indians
1 Viejas Grade Rd.

Alpine, CA 91901
Subject: Information Request for the 9407 Jericho Road Residential Project, City of La Mesa, San Diego County, California
Dear Mr. Pingleton,
The 9407 Jericho Road Residential Project (project) is located at 9407 Jericho Road, in the City of La Mesa, San Diego County, California (Figure 1). The project plans to redevelop the existing site and construct 73 three-story townhomes on a 3.49-acre site. This project falls on Section 16, Township 16 South, Range 1 West in the La Mesa and El Cajon U.S. Geological Survey (USGS) 7.5-minute Quadrangles.

The NAHC emailed a response on February 15, 2024, which stated that the SLF search identified the presence of Native American cultural resources in the immediate project area.

Please note that this letter does not constitute Assembly Bill (AB) 52 notification or initiation of consultation.

Tribes that wish to be notified of projects for the purposes of consultation must contact the lead agency, City of La Mesa (City) in writing (pursuant to Public Resources Code Section 21080.3.1 (b)).

If you have any information or concerns pertaining to such information, please contact me by phone or email.

Respectfully,
_________________
Makayla Murillo, B.A.

Archaeologist
DUDEK
Phone: (760) 846-5874
Email: [email protected]
Attachments: Figure 1. Records Search Map

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February 19, 2024 15823
Mr. Robert Pinto, Chairperson
Ewiaapaayp Band of Kumeyaay Indians
4054 Willow Rd.

Alpine, CA 91901
Subject: Information Request for the 9407 Jericho Road Residential Project, City of La Mesa, San Diego County, California
Dear Mr. Pinto,
The 9407 Jericho Road Residential Project (project) is located at 9407 Jericho Road, in the City of La Mesa, San Diego County, California (Figure 1). The project plans to redevelop the existing site and construct 73 three-story townhomes on a 3.49-acre site. This project falls on Section 16, Township 16 South, Range 1 West in the La Mesa and El Cajon U.S. Geological Survey (USGS) 7.5-minute Quadrangles.

The NAHC emailed a response on February 15, 2024, which stated that the SLF search identified the presence of Native American cultural resources in the immediate project area.

Please note that this letter does not constitute Assembly Bill (AB) 52 notification or initiation of consultation.

Tribes that wish to be notified of projects for the purposes of consultation must contact the lead agency, City of La Mesa (City) in writing (pursuant to Public Resources Code Section 21080.3.1 (b)).

If you have any information or concerns pertaining to such information, please contact me by phone or email.

Respectfully,
_________________
Makayla Murillo, B.A.

Archaeologist
DUDEK
Phone: (760) 846-5874
Email: [email protected]
Attachments: Figure 1. Records Search Map

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February 19, 2024 15823
Ms. Erica Pinto, Chairperson
Jamul Indian Village
P.O. Box 612
Jamul, CA 91935
Subject: Information Request for the 9407 Jericho Road Residential Project, City of La Mesa, San Diego County, California
Dear Ms. Pinto,
The 9407 Jericho Road Residential Project (project) is located at 9407 Jericho Road, in the City of La Mesa, San Diego County, California (Figure 1). The project plans to redevelop the existing site and construct 73 three-story townhomes on a 3.49-acre site. This project falls on Section 16, Township 16 South, Range 1 West in the La Mesa and El Cajon U.S. Geological Survey (USGS) 7.5-minute Quadrangles.

The NAHC emailed a response on February 15, 2024, which stated that the SLF search identified the presence of Native American cultural resources in the immediate project area.

Please note that this letter does not constitute Assembly Bill (AB) 52 notification or initiation of consultation.

Tribes that wish to be notified of projects for the purposes of consultation must contact the lead agency, City of La Mesa (City) in writing (pursuant to Public Resources Code Section 21080.3.1 (b)).

If you have any information or concerns pertaining to such information, please contact me by phone or email.

Respectfully,
_________________
Makayla Murillo, B.A.

Archaeologist
DUDEK
Phone: (760) 846-5874
Email: [email protected]
Attachments: Figure 1. Records Search Map

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February 19, 2024 15823
Ms. Angela Elliott Santos, Chairperson
Manzanita Band of Kumeyaay Nation
P.O. Box 1302
Boulevard, CA 91905
Subject: Information Request for the 9407 Jericho Road Residential Project, City of La Mesa, San Diego County, California
Dear Ms. Santos,
The 9407 Jericho Road Residential Project (project) is located at 9407 Jericho Road, in the City of La Mesa, San Diego County, California (Figure 1). The project plans to redevelop the existing site and construct 73 three-story townhomes on a 3.49-acre site. This project falls on Section 16, Township 16 South, Range 1 West in the La Mesa and El Cajon U.S. Geological Survey (USGS) 7.5-minute Quadrangles.

The NAHC emailed a response on February 15, 2024, which stated that the SLF search identified the presence of Native American cultural resources in the immediate project area.

Please note that this letter does not constitute Assembly Bill (AB) 52 notification or initiation of consultation.

Tribes that wish to be notified of projects for the purposes of consultation must contact the lead agency, City of La Mesa (City) in writing (pursuant to Public Resources Code Section 21080.3.1 (b)).

If you have any information or concerns pertaining to such information, please contact me by phone or email.

Respectfully,
_________________
Makayla Murillo, B.A.

Archaeologist
DUDEK
Phone: (760) 846-5874
Email: [email protected]
Attachments: Figure 1. Records Search Map

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February 19, 2024 15823
Mr. Ray Teran, Resource Manager
Viejas Band of Kumeyaay Indians
1 Viejas Grade Rd.

Alpine, CA 91901
Subject: Information Request for the 9407 Jericho Road Residential Project, City of La Mesa, San Diego County, California
Dear Mr. Teran,
The 9407 Jericho Road Residential Project (project) is located at 9407 Jericho Road, in the City of La Mesa, San Diego County, California (Figure 1). The project plans to redevelop the existing site and construct 73 three-story townhomes on a 3.49-acre site. This project falls on Section 16, Township 16 South, Range 1 West in the La Mesa and El Cajon U.S. Geological Survey (USGS) 7.5-minute Quadrangles.

The NAHC emailed a response on February 15, 2024, which stated that the SLF search identified the presence of Native American cultural resources in the immediate project area.

Please note that this letter does not constitute Assembly Bill (AB) 52 notification or initiation of consultation.

Tribes that wish to be notified of projects for the purposes of consultation must contact the lead agency, City of La Mesa (City) in writing (pursuant to Public Resources Code Section 21080.3.1 (b)).

If you have any information or concerns pertaining to such information, please contact me by phone or email.

Respectfully,
_________________
Makayla Murillo, B.A.

Archaeologist
DUDEK
Phone: (760) 846-5874
Email: [email protected]
Attachments: Figure 1: Records Search Map

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Appendix E
Geotechnical Evaluation

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131 Calle Iglesia, Suite 200, San Clemente, CA 92672 (949) 369-6141 www.lgcgeotechnical.com June 5, 2023 Project No. 23052-01
Ms. Johanna Crooker
Meritage Homes
5 Peters Canyon Road, Suite 310
Irvine, CA 92606
Subject: Preliminary Geotechnical Subsurface Due Diligence Evaluation for the Proposed Residential Development, 9407 Jericho Road, La Mesa, California In accordance with your request, LGC Geotechnical, Inc. has performed a geotechnical subsurface due diligence evaluation for the proposed residential development located at 9407 Jericho Road in the City of La Mesa, California. This report summarizes the results of our background review, subsurface exploration, and geotechnical analyses of the data collected, and presents our findings, conclusions, and preliminary recommendations for the proposed residential project.

If you should have any questions regarding this report, please do not hesitate to contact our office. We appreciate this opportunity to be of service.

Respectfully,
LGC Geotechnical, Inc.

Dennis Boratynec, GE 2770 Branden Petersen, EIT
Vice President Senior Staff Engineer
DJB/BPP/ala
Distribution: (1) Addressee (electronic copy, wet signed copies can be provided upon request)

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Project No. 23052‐01 Page i June 5, 2023

TABLE OF CONTENTS
Section Page

1.0 INTRODUCTION .................................................................................................................2

1.1 Purpose and Scope of Services ...............................................................................2

1.2 Existing Site Conditions and Proposed Improvements .......................................2

1.3 Subsurface Evaluation ...........................................................................................3

1.4 Field Percolation Testing .......................................................................................3

1.5 Laboratory Testing .................................................................................................4

2.0 GEOTECHNICAL CONDITIONS ........................................................................................6

2.1 Regional Geology .....................................................................................................6

2.2 Site Geology and Generalized Subsurface Conditions ...........................................6

2.3 Groundwater ...........................................................................................................6

2.4 Faulting and Seismic Hazards ................................................................................7

2.4.1 Liquefaction and Dynamic Settlement......................................................7

2.4.2 Lateral Spreading .......................................................................................7

2.5 Seismic Design Criteria ...........................................................................................8

2.7 Oversized Material ...............................................................................................10

2.8 Expansion Potential ..............................................................................................10

3.0 CONCLUSIONS ..................................................................................................................11

4.0 RECOMMENDATIONS .....................................................................................................12

4.1 Site Earthwork ......................................................................................................12

4.1.1 Site Preparation ........................................................................................12

4.1.2 Removal Depths and Limits .....................................................................13

4.1.4 Temporary Excavations ...........................................................................14

4.1.5 Removal Bottoms Subgrade Preparation ................................................15

4.1.6 Material for Fill ..........................................................................................15

4.1.7 Placement and Compaction of Fills ..........................................................16

4.1.8 Trench and Retaining Wall Backfill and Compaction .............................16

4.1.9 Shrinkage and Subsidence .......................................................................17

4.2 Preliminary Foundation Recommendations .......................................................17

4.2.1 Preliminary Conventional Foundation Design Parameters ..................18

4.2.2 Provisional Post-Tensioned Foundation Design Parameters ...............18

4.2.3 Shallow Foundation Maintenance...........................................................19

4.2.4 Slab Underlayment Guidelines ................................................................20

4.4 Foundation Setback from Top-of-Slope and Bottom-of-Slope .........................20

4.3 Soil Bearing and Lateral Resistance ....................................................................21

4.4 Lateral Earth Pressures and Retaining Wall Design Considerations ...............21

4.5 Corrosivity to Concrete and Metal ......................................................................23

4.6 Preliminary Asphalt Concrete Pavement Sections ............................................23

4.7 Nonstructural Concrete Flatwork .......................................................................24

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TABLE OF CONTENTS (Cont’d)
Project No. 23052‐01 Page ii June 5, 2023

4.8 Subsurface Water Infiltration ...............................................................................25

4.9 Control of Surface Water and Drainage Control ..................................................26

4.10 Geotechnical Plan Review ....................................................................................26

4.11 Geotechnical Observation and Testing ................................................................27

5.0 LIMITATIONS ...................................................................................................................28

LIST OF TABLES, ILLUSTRATIONS, & APPENDICES
Tables
Table 1 – Summary of Infiltration Testing (Page 4)
Table 2 – Seismic Design Parameters (Page 9)
Table 3 – Preliminary Post-Tensioned Foundation Design Parameters (Page 19) Table 4 – Lateral Earth Pressures – Approved Imported Sandy Soils (Page 22) Table 5 – Preliminary Pavement Sections (Page 24)
Table 6 – Nonstructural Concrete Flatwork for Low Expansion Potential (Page 25) Figures
Figure 1 – Site Location Map (Page 5)
Figure 2 – Geotechnical Map (Rear of Text)
Figure 3 – Retaining Wall Backfill Detail (Rear of Text) Appendices
Appendix A – References
Appendix B – Boring Logs
Appendix C – Laboratory Test Results
Appendix D – Infiltration Test Data
Appendix E – General Earthwork and Grading Specifications for Rough Grading

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Project No. 23052‐01 Page 2 June 5, 2023

1.0 INTRODUCTION

1.1 Purpose and Scope of Services
This report presents the results of our geotechnical subsurface due diligence evaluation for the proposed residential development located at 9407 Jericho Road in the City of La Mesa, California (see Site Location Map, Figure 1). The purpose of our work was to collect subsurface data in order to confirm that the site can be developed from a geotechnical perspective. Our scope of services included:
 Review of pertinent readily available geotechnical information and geologic maps (Appendix A).  Subsurface investigation including excavation, sampling, and logging of five small-diameter hollow stem borings.
 Infiltration testing at two of the small-diameter hollow-stem borings.  Laboratory testing of representative samples obtained during our subsurface evaluation (Appendix C).
 Geotechnical analysis and evaluation of the data obtained, including:
- Suitability of the site for the proposed development from a geotechnical standpoint; - Description of the site geology, and subsurface soil and groundwater conditions; - Evaluation of the seismic conditions at the site, including seismic design criteria based on the 2022 California Building Code (CBC); and
- Recommendations for remedial grading operations and site preparation.  Preparation of this report presenting our findings, conclusions and recommendations with respect to the proposed site development.

1.2 Existing Site Conditions and Proposed Improvements
The approximately 3.5-acre rectangularly shaped site is bound to the north, west, and south by existing residential communities and to the east by Jericho Road. Review of historical aerial photographs suggests the site has been developed since at least 1964. As far back as 1953 there had been a single structure with a driveway and open space. Since 1964 there have been multiple buildings added, improvements to the parking lot, and improvements to the playground. By 1978 communities to the northeast and southwest had also been completely developed. The site is currently a church and contains multiple buildings, a concrete parking lot, an asphalt basketball court, and multiple open grassy areas.

The proposed development will consist of single-family residential with associated improvements. We expect the proposed residential development will be at-grade with relatively light building loads (column and wall loads assumed to be a maximum of approximately 30 kips and 3 kips per lineal foot, respectively). We expect minimal cuts and fills throughout the site on the order of approximately 5 or less.

The recommendations provided herein are based upon the estimated structural loading and expected layout information above. We understand that the project plans are currently being developed at this time; LGC Geotechnical should be provided with updated project plans (including grading plans, retaining walls, etc.) and any changes to the assumed structural loads

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Project No. 23052‐01 Page 3 June 5, 2023
when they become available, in order to either confirm or modify the recommendations provided herein.

1.3 Subsurface Evaluation
LGC Geotechnical performed a subsurface geotechnical evaluation of the site consisting of the excavation of 5 hollow-stem auger borings.

Five hollow-stem borings (HS-1 through HS-3, I-1, and I-2) were drilled to depths ranging from approximately 6.5 to 14 feet below existing grade. An LGC Geotechnical representative observed the drilling operations, logged the borings, and collected soil samples for laboratory testing. The borings were excavated using a truck-mounted drill rig equipped with 8-inch-diameter hollowstem augers. Driven soil samples were collected by means of the Standard Penetration Test (SPT) and Modified California Drive (MCD) sampler generally obtained at 2.5 to 5-foot vertical increments. The MCD is a split-barrel sampler with a tapered cutting tip and lined with a series of 1-inch-tall brass rings. The SPT sampler and MCD sampler were driven using a 140-pound automatic hammer falling 30 inches to advance the sampler a total depth of 18 inches. The raw blow counts for each 6-inch increment of penetration were recorded on the boring logs. Bulk samples were also collected and logged at select depths for laboratory testing. At the completion of drilling, the borings were backfilled with the native soil cuttings and tamped. Some settlement of the backfill soils may occur over time.

The approximate locations of borings are shown on the Geotechnical Map (Figure 2). Boring logs are presented in Appendix B.

1.4 Field Percolation Testing
Two falling head field percolation tests (I-1 and I-2) were performed in the approximate locations indicated on our Geotechnical Map (Figure 2). Estimation of infiltration rates for the site was accomplished in general accordance with the guidelines set forth by the County of San Diego (2020). A 3-inch diameter perforated PVC pipe with filter sock was placed in the borehole, and the annulus was backfilled with gravel, including placement of approximately 2 inches of gravel at the bottom of the borehole. The infiltration wells were pre-soaked the day prior to testing. During the pre-test, if the water level drops more than 6 inches in 25 minutes for two consecutive readings, the test procedure for coarse-grained soils was followed. If the water level did not drop 6 inches in one or both pre-test readings, the procedure for finegrained soils was followed. The procedure for coarse-grained soils requires performing the test for one hour and taking one reading every 10 minutes from a fixed reference point. The procedure for fine-grained soils requires performing the test for six hours and taking one reading every 30 minutes from a fixed reference point.

The pre-tests indicated the procedure for fine-grained soils should be followed. The calculated infiltration is normalized relative to the three-dimensional flow that occurs within the field test to a one-dimensional flow out of the bottom of the boring only (i.e., “Porchet Method”). The measured infiltration rates (for feasibility purposes only) are provided in Table 1 below. Please note that infiltration is discussed in Section 4.8 and field data is provided in Appendix D.

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Project No. 23052‐01 Page 4 June 5, 2023
TABLE 1
Summary of Field Infiltration Testing
Infiltration Test
No.

Approx. Depth
Below Existing
Grade (ft)
Measured
Infiltration Rate*
(in./hr.)
I-1 10 0.005
I-2 10 0.007
*Measured Infiltration Rates Do Not Include Factor of Safety.

1.5 Laboratory Testing
Laboratory testing was performed on representative soil samples obtained from our subsurface evaluation. Laboratory testing included in-situ moisture and density tests, fines content, collapse testing, expansion index, laboratory compaction and corrosion.

The following is a summary of the laboratory test results.  Dry density of the samples collected ranged from approximately 92 pounds per cubic foot (pcf) to 113 pcf, with an average of approximately 104 pcf. Field moisture contents ranged from approximately 4 percent to 23 percent, with an average of approximately 11 percent.  Two samples were tested for fines content indicating a fines content (passing No. 200 sieve) ranging from 26 to 32 percent. According to the Unified Soils Classification System (USCS), the tested samples are classified “coarse grained” soil.  Two collapse tests were performed. The deformation versus vertical stress plot is provided in Appendix C.
 Two Expansion Index (EI) tests were performed. The results indicate an EI value ranging from 23 to 31, corresponding to “Low” expansion potential.  Two laboratory compaction tests of near surface samples indicated maximum dry density ranging from 124.5 to 129.5 pcf with an optimum moisture content ranging from 7.5 to

10.5 percent.
 Corrosion testing indicated soluble sulfate content of 66 parts per million (ppm), chloride content of 200 ppm, and pH value of 7.29, and minimum resistivity of 1870 ohm-cm.

A summary of the results is presented in Appendix C. The moisture and dry density test results are presented on the boring logs in Appendix B.

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Approximate Site Location
FIGURE 1
Site Location Map
DATE June 2023
ENG. / GEOL.

PROJECT NO.

PROJECT NAME
SCALE
DJB
Not to Scale
Meritage - 9407 Jericho Road, La Mesa
23052-01

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Project No. 23052‐01 Page 6 June 5, 2023

2.0 GEOTECHNICAL CONDITIONS

2.1 Regional Geology
Regionally the site is located within the coastal sub-province of the Peninsular Ranges Geomorphic Province, near the western edge of the Southern California batholith. The topography at the edge of the batholith changes from the rugged landforms developed on the batholith to the more subdued landforms, which typify the softer, sedimentary formations of the coastal plain. Tertiary and Quaternary rocks are generally comprised of marine and nonmarine sediments consisting of sandstone, mudstones, conglomerates, and occasional volcanic units. Erosion and regional tectonic uplift created the valleys and ridges of the area.

Regional geologic mapping and local topographic expressions do not indicate the presence of large-scale landslides within or adjacent to the project area.

2.2 Site Geology and Generalized Subsurface Conditions
Based on regional mapping (USGS, 2002), the subject site is underlain by the Mission Valley Formation (Tmv). Throughout the site the Mission Valley Formation is overlain by older artificial fill that was placed during the development of the existing development. The depth of this older artificial fill was found to range from approximately 2.5 to 7.5 feet below existing grade during our evaluation but may be found at a deeper depths during grading. As indicated in our field explorations, site soils generally consisted of very loose/soft to very dense/hard clayey sands and sandy clays with varying amount of gravel/cobbles to the maximum explored depth of approximately 14 feet below existing grade. Difficult drilling conditions and auger refusal were encountered during drilling.

It should be noted that borings are only representative of the location and time where/when they are performed, and varying subsurface conditions may exist outside of the performed location. In addition, subsurface conditions can change over time. The soil descriptions provided should not be construed to mean that the subsurface profile is uniform, and that soil is homogenous within the project area. Descriptions of the subsurface conditions are presented on the boring and geotechnical trench logs located in Appendix B.

2.3 Groundwater
Groundwater was not encountered to the maximum explored depth of approximately 14 feet.

In general, groundwater levels fluctuate with the seasons and local zones of perched groundwater may be present within the near-surface deposits due to local seepage or during rainy seasons. Groundwater conditions below the site may be variable, depending on numerous factors including seasonal rainfall, local irrigation and groundwater pumping, among others.

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Project No. 23052‐01 Page 7 June 5, 2023

2.4 Faulting and Seismic Hazards
Prompted by damaging earthquakes in California, State legislation and policies concerning the classification and land-use criteria associated with faults have been developed. Their purpose was to prevent the construction of urban developments across the trace of active faults, resulting in the Alquist-Priolo Earthquake Fault Zoning Act. Earthquake Fault Zones have been delineated along the traces of active faults within California. Where developments for human occupation are proposed within these zones, the State requires detailed fault evaluations be performed so that engineering geologists can mitigate the hazards associated with active faulting by identifying the location of active faults and allowing for a setback from zones of previous ground rupture.

The subject site is not located within an Alquist-Priolo Earthquake Fault Zone and no faults were identified on the site during our site evaluation. The possibility of damage due to ground rupture is considered low since no active faults are known to cross the site.

Secondary effects of seismic shaking resulting from large earthquakes on the major faults in the Southern California region, which may affect the site, include ground lurching, shallow ground rupture, soil liquefaction and dynamic settlement. These secondary effects of seismic shaking are a possibility throughout the Southern California region and are dependent on the distance between the site and causative fault and the onsite geology. Some of the major active nearby faults that could produce these secondary effects include the Rose Canyon and Oceanside Faults, among others (CGS, 2018). A discussion of these secondary effects is provided in the following sections.

2.4.1 Liquefaction and Dynamic Settlement
Liquefaction is a seismic phenomenon in which loose, saturated, granular soils behave similarly to a fluid when subject to high-intensity ground shaking. Liquefaction occurs when three general conditions coexist: 1) shallow groundwater; 2) low density noncohesive (granular) soils; and 3) high-intensity ground motion. Studies indicate that loose, saturated, near-surface, cohesionless soils exhibit the highest liquefaction potential, while dry, dense, cohesionless soils, and cohesive soils exhibit low to negligible liquefaction potential. In general, cohesive soils are not considered susceptible to liquefaction. Effects of liquefaction on level ground include settlement, sand boils, and bearing capacity failures below structures. Furthermore, dynamic settlement of dry sands can occur as the sand particles tend to settle and densify as a result of a seismic event.

Based on our review of the San Diego County Liquefaction Hazard Map, the subject site is not located in an area of liquefaction susceptibility. Based on our evaluation, site soils are generally not susceptible to liquefaction due to very dense/hard native soils; therefore, liquefaction potential is considered low.

2.4.2 Lateral Spreading
Lateral spreading is a type of liquefaction induced ground failure associated with the

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Project No. 23052‐01 Page 8 June 5, 2023
lateral displacement of surficial blocks of sediment resulting from liquefaction in a subsurface layer. Once liquefaction transforms the subsurface layer into a fluid mass, gravity plus the earthquake inertial forces may cause the mass to move downslope towards a free face (such as a river channel or an embankment). Lateral spreading may cause large horizontal displacements and such movement typically damages pipelines, utilities, bridges, and structures.

Due to the low probability of liquefaction, the potential for lateral spreading is considered low.

2.5 Seismic Design Criteria
The site seismic characteristics were evaluated per the guidelines set forth in Chapter 16, Section 1613 of the 2022 California Building Code (CBC) and applicable portions of ASCE 7-16 which has been adopted by the CBC. Please note that the following seismic parameters are only applicable for code-based acceleration response spectra and are not applicable for where sitespecific ground motion procedures are required by ASCE 7-16. Representative site coordinates of latitude 32.786725 degrees north and longitude -116.994087 degrees west were utilized in our analyses. The maximum considered earthquake (MCE) spectral response accelerations (SMS and SM1) and adjusted design spectral response acceleration parameters (SDS and SD1) for Site Class C are provided in Table 2 on the following page. The structural designer should contact the geotechnical consultant if structural conditions (e.g., number of stories, seismically isolated structures, etc.) require site-specific ground motions.

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TABLE 2
Seismic Design Parameters
Selected Parameters from 2022 CBC,
Section 1613 ‐ Earthquake Loads
Seismic
Design
Values
Notes/Exceptions
Distance to applicable faults classifies the site as a
“Near-Fault” site. Section 11.4.1 of ASCE 7
Site Class C Chapter 20 of ASCE 7
Ss (Risk-Targeted Spectral Acceleration
for Short Periods) 0.780g From SEAOC, 2023
S1 (Risk-Targeted Spectral
Accelerations for 1-Second Periods) 0.285g From SEAOC, 2023 Fa (per Table 1613.2.3(1)) 1.2
For Simplified Design Procedure
of Section 12.14 of ASCE 7, Fa
shall be taken as 1.4 (Section

12.14.8.1)
Fv (per Table 1613.2.3(2)) 1.5 -
SMS for Site Class C
[Note: SMS = FaSS] 0.936g -
SM1 for Site Class C
[Note: SM1 = FvS1] 0.428g -
SDS for Site Class C
[Note: SDS = (2/3) SMS] 0.624g -
SD1 for Site Class C
[Note: SD1 = (2/3) SM1] 0.285g -
CRS (Mapped Risk Coefficient at 0.2 sec) 0.917 ASCE 7 Chapter 22 CR1(Mapped Risk Coefficient at 1 sec) 0.922 ASCE 7 Chapter 22 A deaggregation of the PGA based on a 2,475-year average return period (MCE) indicates that an earthquake magnitude of 6.42 at a distance of approximately 17.7 km from the site would contribute the most to this ground motion. A deaggregation of the PGA based on a 475-year average return period (Design Earthquake) indicates that an earthquake magnitude of 6.52 at a distance of approximately 28.1 km from the site would contribute the most to this ground motion (USGS, 2014).

Section 1803.5.12 of the 2022 CBC (per Section 11.8.3 of ASCE 7) states that the maximum considered earthquake geometric mean (MCEG) Peak Ground Acceleration (PGA) should be used for liquefaction potential. The PGAM for the site is equal to 0.402g (SEAOC, 2023). The design PGA is equal to 0.268g (2/3 of PGAM).

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Project No. 23052‐01 Page 10 June 5, 2023

2.6 Oversized Material
Oversized material (material larger than 8 inches in maximum dimension) are very likely to be encountered during site grading based on our subsurface evaluation and an observation of oversized materials located in the landscaping areas onsite and in the surrounding neighborhood. Recommendations are provided for appropriate handling of oversized materials in Appendix E. If feasible, crushing oversized materials onsite or exporting oversized materials may be considered. Incorporating oversized materials into “rock fills” (windrows, rock blankets or individual rock burial) is likely not feasible due to the limited depth of grading. Special handling recommendations should be provided on a case-by case basis, if necessary.

2.7 Expansion Potential
Based on the results of laboratory testing from our evaluation and by others, finished grade soils are anticipated to have a “Low” expansion potential. Final expansion potential of site soils should be determined at the completion of grading.

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3.0 CONCLUSIONS
Based on the results of our subsurface geotechnical evaluation, it is our opinion that the proposed improvements are feasible from a geotechnical standpoint, provided that the recommendations contained in the following sections are incorporated during site grading and development. A summary of our geotechnical conclusions are as follows:
 The near-surface loose and compressible soils are not suitable for the planned improvements in their present condition (refer to Section 4.1).
 Groundwater was not encountered during our subsurface evaluation to a maximum depth of approximately 14 feet below current grade.
 The subject study area is not located within a mapped State of California Earthquake Fault Zone, and based upon our review of published geologic mapping, no known active or potentially active faults are known to exist within or in the immediate vicinity of the site. Therefore, the potential for ground rupture as a result of faulting is considered very low.  The main seismic hazard that may affect the site is ground shaking from one of the active regional faults. The subject site will likely experience strong seismic ground shaking during its design life.  Based on our evaluation, site soils are generally not susceptible to liquefaction due to very dense/hard native soils; therefore, liquefaction potential is considered low.  Based on the results of preliminary laboratory testing, site soils are anticipated to have “Low” expansion potential. Final design expansion potential must be determined at the completion of grading.
 Excavations into the existing site soils should be feasible with heavy construction equipment in good working order. We anticipate that soils generated from the excavations will be generally suitable for re-use as compacted fill, provided they are relatively free of rocks larger than 8 inches in dimension, construction debris, and significant organic material.  Oversized materials (greater than 8 inches in maximum dimension) are very likely to be encountered during site grading. Recommendations are provided for appropriate handling of oversized materials in Appendix E.
 Some portions of the onsite soils have high fines content/expansion potential; therefore, are not suitable for backfill of site retaining walls. Therefore, stockpiling of on-site sandy material or import of sandy soils meeting project recommendations may be required.  Field testing resulted in measured infiltration rates ranging from 0.005 to 0.007 inches per hour.

The measured infiltration rates do not include a factor of safety. Discussion regarding infiltration is provided in Section 4.8.

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Project No. 23052‐01 Page 12 June 5, 2023

4.0 RECOMMENDATIONS
The following recommendations are to be considered preliminary and should be confirmed upon completion of grading and earthwork operations. In addition, they should be considered minimal from a geotechnical viewpoint, as there may be more restrictive requirements from the architect, structural engineer, building codes, governing agencies, or the owner.

It should be noted that the following geotechnical recommendations are intended to provide sufficient information to develop the site in general accordance with the 2022 CBC requirements. With regard to the possible occurrence of potentially catastrophic geotechnical hazards such as fault rupture, earthquake-induced landslides, liquefaction, etc. the following geotechnical recommendations should provide adequate protection for the proposed development to the extent required to reduce seismic risk to an “acceptable level.” The “acceptable level” of risk is defined by the California Code of Regulations as “that level that provides reasonable protection of the public safety, though it does not necessarily ensure continued structural integrity and functionality of the project” [Section 3721(a)].

Therefore, repair and remedial work of the proposed improvement may be required after a significant seismic event. With regards to the potential for less significant geologic hazards to the proposed development, the recommendations contained herein are intended as a reasonable protection against the potential damaging effects of geotechnical phenomena such as expansive soils, fill settlement, groundwater seepage, etc. It should be understood, however, that our recommendations are intended to maintain the structural integrity of the proposed development and structures given the site geotechnical conditions but cannot preclude the potential for some cosmetic distress or nuisance issues to develop as a result of the site geotechnical conditions.

The geotechnical recommendations contained herein must be confirmed to be suitable or modified based on the actual as-graded conditions.

4.1 Site Earthwork
Rough grading shall include remedial earthwork grading and placement of engineered compacted fill to design grades. Geotechnical recommendations for precise grading and construction of the proposed new improvements will be provided, as necessary.

We recommend that earthwork onsite be performed in accordance with the following recommendations, future grading plan review report(s), the 2022 CBC/City of La Mesa requirements, and the General Earthwork and Grading Specifications for Rough Grading included in Appendix E. In case of conflict, the following recommendations shall supersede those included in Appendix E. The following recommendations may be revised within future grading plan review reports or based on the actual conditions encountered during site grading.

4.1.1 Site Preparation
Prior to grading, areas to be developed should undergo the stripping and clearing of vegetation and clearing of surface obstructions, pavements, foundation and slab elements

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from the site. Vegetation, debris from the previous land use and excessive organic material should be removed and properly disposed of offsite. Holes resulting from removals of buried obstructions, which extend below proposed remedial and/or finish grades, should be replaced with suitable compacted fill material. If the demolition contractor removes subsurface utilities below the proposed remedial grading depth we recommend the excavations either be left open until grading operations begin or properly compacted to the depth of remedial grading.

If cesspools or septic systems are encountered, they should be removed in their entirety.

The resulting excavation should be backfilled with properly compacted fill soils. As an alternative, cesspools can be backfilled with lean sand-cement slurry. Any encountered wells should be properly abandoned in accordance with regulatory requirements.

4.1.2 Removal Depths and Limits
In order to provide a relatively uniform bearing condition for the planned building structure and improvements, we recommend the site soils be removed and recompacted. Compressible near surface soils shall be removed to suitable, competent native materials prior to re-placement as compacted fill to design grades. Subsurface site soils should be removed and recompacted according to the criteria outlined below.

Buildings: We recommend that soils within the proposed building footprint areas be removed and recompacted to a minimum depth of 5 to 10 feet below existing grade or 3 feet beneath the base of the foundations, whichever is deeper. The estimated minimum removal depth below existing grade locations can be found in the Geotechnical Map (Figure 2). Additionally, existing undocumented fill encountered during grading should be removed and recompacted for use as compacted fill. The envelope for removal and recompaction should extend laterally a minimum distance equal to the depth of the removal and recompaction below finish grade or 5 feet beyond the edges of the proposed building improvements, whichever is larger. Localized deeper removal and recompaction may be required.

Note: Remedial grading recommendations along the descending slope along the southeasterly side of the site will be provided once the grading plan (and retaining wall plans) have been developed. For budgetary purposes we recommend a toe of slope “keyway” be included that is 15 feet wide and wraps around the entire descending slope. Additional subsurface geotechnical explorations, lab testing and analysis will likely be required to assess the stability of the descending slope.

For minor site structures, such as free-standing, minor retaining walls, etc., removal and recompaction should extend at least 3 feet beneath existing grade or 2 feet beneath the base of foundations, whichever is deeper. In general, the envelope for removal and recompaction should extend laterally a minimum distance of 3 feet beyond the edges of the proposed improvements mentioned above. It is our understanding that some midslope retaining walls are proposed near the southeastern edge of the property line. It is recommended that these retaining walls be supported by deepened footings/deep

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foundations in order to eliminate added lateral loads to the existing slope or retaining walls below the proposed retaining walls. To eliminate this added lateral load, the retaining wall footing must project a 1:1 below the existing toe of slope. Depending on the proximity of the proposed retaining wall inside property line and the offsite homeowners modified slopes or retaining walls, this slope will require additional subsurface field work and analysis during final engineering depending on the finalized grading plan.

Within pavement and hardscape areas, the soils should be removed and replaced as properly compacted fill to a minimum depth of 2 feet below existing grade or 1-foot below the proposed finished subgrade, whichever is deeper. In general, the envelope for removal and recompaction should extend laterally a minimum distance of 2 feet beyond the edges of the proposed improvements mentioned above.

Local conditions may be encountered which could require additional removal and recompaction beyond the above-noted minimum to obtain an acceptable subgrade. The actual depths and lateral extents of removal and recompaction should be determined by the geotechnical consultant based on the subsurface conditions encountered during grading. Removal and recompaction areas and areas should be accurately staked/recorded in the field by the Project Surveyor.

4.1.3 Temporary Excavations
Temporary excavations should be performed in accordance with project plans, specifications, and applicable Occupational Safety and Health Administration (OSHA) requirements. Excavations should be laid back or shored in accordance with OSHA requirements before personnel or equipment are allowed to enter. Based on our field investigation, the majority of site soils are anticipated to be OSHA Type “C” soils (refer to the attached boring logs). Sandy soils are present and should be considered susceptible to caving. Soil conditions should be regularly evaluated during construction to verify conditions are as anticipated. The contractor shall be responsible for providing the “competent person” required by OSHA standards to evaluate soil conditions. Close coordination with the geotechnical consultant should be maintained to facilitate construction while providing safe excavations. Excavation safety is the sole responsibility of the contractor.

Where proposed improvements will be adjacent to property lines, the potential for impacting existing offsite improvements may be reduced by performing “ABC” slot cuts while performing earthwork removal and recompaction. “ABC” slot cuts are defined as excavations perpendicular to sensitive property boundaries that are divided into multiple “slots” of equal width. If slots are labeled A, B, C, A, B, C, etc., then all “A” slots can be excavated at the same time but must be backfilled before all “B” slots can be excavated, etc. Any given slot should be backfilled immediately with properly compacted fill to finish grade prior to excavation of the adjacent two slots. Please note some sands susceptible to caving are present at the site. Recommendations for slot cut dimensions should be evaluated during grading. Protection of the existing offsite improvements during grading is the responsibility of the contractor.

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Vehicular traffic, stockpiles, and equipment storage should be set back from the perimeter of excavations a minimum distance equivalent to a 1:1(horizontal to vertical) projection from the bottom of the excavation or 5 feet, whichever is greater. Once an excavation has been initiated, it should be backfilled as soon as practical. Prolonged exposure of temporary excavations may result in some localized instability. Excavations should be planned so that they are not initiated without sufficient time to shore/fill them prior to weekends, holidays, or forecasted rain.

It should be noted that any excavation that extends below a 1:1 (horizontal to vertical) projection of an existing foundation will remove existing support of the structure foundation. If requested, temporary shoring parameters will be provided.

4.1.4 Removal Bottoms and Subgrade Preparation
In general, areas to receive compacted fill should be scarified to a minimum depth of 6 inches, brought to a near-optimum moisture condition (generally within optimum and 2 percent above optimum moisture content), and re-compacted per project requirements.

Removal bottoms, over-excavation bottoms and areas to receive fill should be observed and accepted by the geotechnical consultant prior to subsequent fill placement. Soil subgrade for planned footings and improvements (e.g., slabs, etc.) should be firm and competent.

4.1.5 Material for Fill
From a geotechnical perspective, the onsite soils are generally considered suitable for use as general compacted fill, provided they are screened of significant organic materials, construction debris and any oversized material (8 inches in greatest dimension).

From a geotechnical viewpoint, import soils for general fill (i.e., non-retaining wall backfill) should consist of clean, granular soils of Low expansion potential (expansion index 50 or less based on ASTM D4829). Import for retaining wall backfill should meet the criteria outlined in the paragraph below. Source samples should be provided to the geotechnical consultant for laboratory testing a minimum of three working days prior to any planned importation.

Retaining wall backfill should consist of imported sandy soils with a maximum of 35 percent fines (passing the No. 200 sieve) per ASTM Test Method D1140 (or ASTM D6913/D422) and a “Very Low” expansion potential (EI of 20 or less per ASTM D4829).

Soils should also be screened of organic materials, construction debris, and any material greater than 3 inches in maximum dimension.

Aggregate base should conform to the requirements of Section 200-2 of the most recent version of the Standard Specifications for Public Works Construction (“Greenbook”) for untreated base materials and/or City of La Mesa requirements.

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The placement of demolition materials in compacted fill is acceptable from a geotechnical viewpoint provided the demolition material is broken up into pieces not larger than typically used for aggregate base (approximately 2 to 4 inches in maximum dimension) and well blended into fill soils with essentially not resulting voids. Demolition material placed in fills must be free of construction debris (wood, organics, etc.) and reinforcing steel. If you elect to incorporate asphalt concrete fragments into the fill materials, approval from an environmental viewpoint and/or local agency may be required and is not the purview of the geotechnical consultant. From our previous experience, we recommend that asphalt concrete fragments be limited to fill areas within planned street areas (i.e. not within building pad areas).

4.1.6 Placement and Compaction of Fills
Material to be placed as fill should be brought to near-optimum moisture content (generally within optimum and 2 percent above optimum moisture content) and recompacted to at least 90 percent relative compaction (per ASTM D1557). Moisture conditioning of site soils will be required in order to achieve adequate compaction. Drying and/or mixing the very moist soils will be required prior to reusing the materials in compacted fills. Soils are also present that will require additional moisture in order to achieve the required compaction.

The optimum lift thickness to produce a uniformly compacted fill will depend on the type and size of compaction equipment used. In general, fill should be placed in uniform lifts not exceeding 8 inches in compacted thickness. Each lift should be thoroughly compacted and accepted prior to subsequent lifts. Generally, placement and compaction of fill should be performed in accordance with local grading ordinances and with observation and testing by LGC Geotechnical. Oversized material as previously defined should be removed from site fills.

During backfill of excavations, the fill should be properly benched into firm and competent soils of temporary backcut slopes as it is placed in lifts.

Aggregate base material should be compacted to a minimum of 95 percent relative compaction at or slightly above optimum moisture content per ASTM D1557. Subgrade below aggregate base should be compacted to a minimum of 90 percent relative compaction per ASTM D1557 at near-optimum moisture content (generally within optimum and 2 percent above optimum moisture content).

4.1.7 Trench and Retaining Wall Backfill and Compaction The onsite soils may generally be suitable as trench backfill, provided the soils are screened of rocks and other material greater than 6 inches in diameter and organic matter. If trenches are shallow or the use of conventional equipment may result in damage to the utilities, sand having a sand equivalent (SE) of 30 or greater (per California Test Method [CTM] 217) may be used to bed and shade the pipes. Sand backfill within the pipe bedding zone may be densified by jetting or flooding and then tamping to ensure

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adequate compaction. Subsequent trench backfill should be compacted in uniform thin lifts by mechanical means to at least the recommended minimum relative compaction (per ASTM D1557).

Retaining wall backfill should consist of sandy soils or native soils as outlined in preceding Section 4.1.5. The contractor should anticipate the importing of soils for the required retaining wall backfill. The limits of select sandy backfill should extend a minimum ½ the height of the retaining wall or the width of the heel (if applicable), whichever is greater, refer to Figure 3. Retaining wall backfill soils should be compacted in relatively uniform thin lifts to at least 90 percent relative compaction (per ASTM D1557). Jetting or flooding of retaining wall backfill materials should not be permitted.

A representative from LGC Geotechnical should observe, probe, and test the backfill to verify compliance with the project recommendations.

4.1.8 Shrinkage and Subsidence
Allowance in the earthwork volumes budget should be made for an estimated 10-15 percent reduction in volume of the upper approximate 2.5 feet of site soils and 0-10 percent reduction in the soils below 2.5 feet. It should be stressed that these values are only estimates and that an actual shrinkage factor would be extremely difficult to predetermine. Subsidence due to earthwork equipment is expected to be on the order of 0.1 feet. These values are estimates only and exclude losses due to removal of vegetation or debris. The effective shrinkage of onsite soils will depend primarily on the type of compaction equipment, method of compaction used onsite by the contractor and accuracy of the topographic survey. The above shrinkage estimates are intended as an aid for project engineers in determining preliminary earthwork quantities. However, these estimates should be used with some caution since they are not absolute values.

Contingencies such as a balance pad should be made for balancing earthwork quantities based on actual shrinkage and subsidence that occurs during grading. The shrinkage and bulking are also expected to vary with variations in survey accuracy during rough grading.

4.2 Preliminary Foundation Recommendations
Provided that the remedial grading recommendations provided herein are implemented, the site may be considered suitable for the support of the residential structures using a conventional or post-tensioned foundation system designed to resist the impacts of expansive soils. Site soils are anticipated to be of Low expansion potential (EI of 50 or less per ASTM D4829). However, this must be verified based on as-graded conditions. Please note that the following foundation recommendations are preliminary and must be confirmed by LGC Geotechnical at the completion of project plans (i.e., foundation, grading and site layout plans) as well as completion of earthwork. Recommended soil bearing and estimated static settlement are provided in Section

4.3.

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4.2.1 Preliminary Conventional Foundation Design Parameters Conventional foundations may be designed in accordance with Wire Reinforcement Institute (WRI) procedure for slab-on-ground foundations per Section 1808 of the 2022 CBC to resist expansive soils. The following preliminary soil parameters may be used:
 Effective Plasticity Index: 15
 Climatic Rating: Cw = 15
 Reinforcement: Per structural designer.
 12-inch minimum perimeter footing/thickened edge embedment below finish grade.
 Moisture condition subgrade soils to 100 % of optimum moisture content to a depth of 12 inches prior to trenching for footings.

4.2.2 Provisional Post‐Tensioned Foundation Design Parameters The geotechnical parameters provided herein may be used for post-tensioned slab foundations with a deepened perimeter footing or a post-tensioned mat slab. These parameters have been determined in general accordance with the Post-Tensioning Institute (PTI) Standard Requirements for Design of Shallow Post-Tensioned Concrete Foundations on Expansive Soils, referenced in Chapter 18 of the 2022 CBC. In utilizing these parameters, the foundation engineer should design the foundation system in accordance with the allowable deflection criteria of applicable codes and the requirements of the structural designer/architect. Other types of stiff slabs may be used in place of the CBC post-tensioned slab design provided that, in the opinion of the foundation structural designer, the alternative type of slab is at least as stiff and strong as that designed by the CBC/PTI method.

Our design parameters are based on our experience with similar projects, test results onsite, and the anticipated nature of the soil (with respect to expansion potential).

Please note that implementation of our recommendations will not eliminate foundation movement (and related distress) should the moisture content of the subgrade soils fluctuate. It is the intent of these recommendations to help maintain the integrity of the proposed structures and reduce (not eliminate) movement, based upon the anticipated site soil conditions. Should future owners and/or property maintenance personnel not properly maintain the areas surrounding the foundation, for example by overwatering, then we anticipate for highly expansive soils the maximum differential movement of the perimeter of the foundation to the center of the foundation to be on the order of a couple of inches. Soils of lower expansion potential are anticipated to show less movement.

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TABLE 3
Preliminary Post‐Tensioned Foundation Design Parameters Parameter
PT Slab with
Perimeter
Footing
PT Mat with
Thicken
ed Edge
Expansion Index Low1 Low1
Thornthwaite Moisture Index -20 -20
Constant Soil Suction PF 3.9 PF 3.9
Center Lift
Edge moisture variation distance, em
Center lift, ym

9.0 feet

0.25 inch

9.0 feet

0.3 inch
Edge Lift
Edge moisture variation distance, em
Edge lift, ym

5.5 feet

0.55 inches

5.5 feet

0.66 inches
Modulus of Subgrade Reaction, k (assuming
presoaking as indicated below) 200 pci 200 pci
Minimum perimeter footing/thickened edge
embedment below finish grade 12 inches 6 inches
Minimum Slab Thickness
5 inches2 8 inches2
Presoak 100% of Opt.
12 inches
100% of Opt.
12 inches

1. Assumed for preliminary design purposes. Further evaluation is needed at the completion of grading.

2. Recommendations for foundation reinforcement and slab thickness are ultimately the purview of the foundation engineer/structural engineer based upon geotechnical criteria and structural engineering considerations.

3. Recommendations for vapor retarders below slabs are also the purview of the foundation engineer/structural engineer and should be provided in accordance with applicable code requirements.

4.2.3 Shallow Foundation Maintenance
The geotechnical parameters provided herein assume that if the areas adjacent to the foundation are planted and irrigated, these areas will be designed with proper drainage and adequately maintained so that ponding, which causes significant moisture changes below the foundation, does not occur. Our recommendations do not account for excessive irrigation and/or incorrect landscape design. Plants should only be provided with sufficient irrigation for life and not overwatered to saturate subgrade soils. Sunken planters placed adjacent to the foundation should either be designed with an efficient drainage system or liners to prevent moisture infiltration below the foundation. Some

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lifting of the perimeter foundation beam should be expected even with properly constructed planters.

In addition to the factors mentioned above, future owners/property management personnel should be made aware of the potential negative influences of trees and/or other large vegetation. Roots that extend near the vicinity of foundations can cause distress to foundations. Future owners (and the owner’s landscape architect) should not plant trees/large shrubs closer to the foundations than a distance equal to half the mature height of the tree or 20 feet, whichever is more conservative unless specifically provided with root barriers to prevent root growth below the building foundation.

It is the owner’s responsibility to perform periodic maintenance during hot and dry periods to ensure that adequate watering has been provided to keep soil from separating or pulling back from the foundation. Future owners and property management personnel should be informed and educated regarding the importance of maintaining a constant level of soil-moisture. The owners should be made aware of the potential negative consequences of both excessive watering, as well as allowing potentially expansive soils to become too dry. Expansive soils can undergo shrinkage during drying, and swelling during the rainy winter season, or when irrigation is resumed. This can result in distress to building structures and hardscape improvements. The builder should provide these recommendations to future owners and property management personnel.

4.2.4 Slab Underlayment Guidelines
The following is for informational purposes only since slab underlayment (e.g., moisture retarder, sand or gravel layers for concrete curing and/or capillary break) is unrelated to the geotechnical performance of the foundation and thereby not the purview of the geotechnical consultant. Post-construction moisture migration should be expected below the foundation. The foundation engineer/architect should determine whether the use of a capillary break (sand or gravel layer), in conjunction with the vapor retarder, is necessary or required by code. Sand layer thickness and location (above and/or below vapor retarder) should also be determined by the foundation engineer/architect.

4.2.5 Foundation Setback from Top‐of‐Slope and Bottom‐of‐Slope Foundations should be setback from the top and bottom of slopes in accordance with the City of La Mesa grading code or California Building Code (CBC), whichever is more conservative. Per the 2022 CBC, the minimum top-of-slope setback is H/3, with a maximum required setback of 40 feet, where H is the total height of the slope. The minimum bottom-of-slope setback is H/2, with a maximum required setback of 15 feet.

Refer to Chapter 18 of the 2022 CBC for additional information. It is the purview of the project civil engineer to implement the appropriate foundation setbacks.

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4.3 Soil Bearing and Lateral Resistance
Provided our earthwork recommendations are implemented, an allowable soil bearing pressure of 1,500 pounds per square foot (psf) may be used for the design of footings having a minimum width of 12 inches and minimum embedment of 12 inches below lowest adjacent ground surface.

This value may be increased by 300 psf for each additional foot of embedment and 150 psf for each additional foot of foundation width to a maximum value of 2,500 psf. A mat foundation a minimum of 6 inches below lowest adjacent grade may be designed for an allowable soil bearing pressure of 1,200 psf. These allowable bearing pressures are applicable for level (ground slope equal to or flatter than 5H:1V) conditions only. Bearing values indicated are for total dead loads and frequently applied live loads and may be increased by ⅓ for short duration loading (i.e., wind or seismic loads).

In utilizing the above-mentioned allowable bearing capacity and provided our earthwork recommendations are implemented, foundation settlement due to structural loads is anticipated to be 1-inch or less. Differential settlement may be taken as half of the total settlement (i.e., ½- inch over a horizontal span of 40 feet).

Resistance to lateral loads can be provided by friction acting at the base of foundations and by passive earth pressure. For concrete/soil frictional resistance, an allowable coefficient of friction of 0.3 may be assumed with dead-load forces. An allowable passive lateral earth pressure of 200 psf per foot of depth (or pcf) to a maximum of 2,000 psf may be used for the sides of footings poured against properly compacted fill. Allowable passive pressure may be increased to 270 pcf (maximum of 2,700 psf) for short duration seismic loading. This passive pressure is applicable for level (ground slope equal to or flatter than 5H:1V) conditions only. Frictional resistance and passive pressure may be used in combination without reduction. We recommend that the upper foot of passive resistance be neglected if finished grade will not be covered with concrete or asphalt. The provided allowable passive pressures are based on a factor of safety of 1.5 and 1.1 for static and seismic loading conditions, respectively. The structural designer should incorporate appropriate factors of safety and/or load factors in their design.

4.4 Lateral Earth Pressures and Retaining Wall Design Considerations The following may be used for design of site retaining walls. Lateral earth pressures are provided as equivalent fluid unit weights, in psf per foot of depth (or pcf). These values do not contain an appreciable factor of safety, so the retaining wall designer should apply the applicable factors of safety and/or load factors during design. A soil unit weight of 120 pcf may be assumed for calculating the actual weight of soil over the wall footing.

The following lateral earth pressures are presented in Table 4 below, for approved import free draining, clean granular (sandy) soils with a maximum of 35 percent fines (passing the No. 200 sieve per ASTM D-421/422) and a “Very Low” expansion potential (EI of 20 or less per ASTM D4829). The site soils are not suitable for retaining wall backfill due to their fines content and expansion index; therefore, import of soils meeting the criteria outlined above will be required by the contractor for obtaining suitable retaining wall backfill soil. The wall designer should clearly indicate on the retaining wall plans the required select sandy soil backfill criteria. These preliminary findings should be confirmed during grading.

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TABLE 4
Lateral Earth Pressures –Approved Imported Sandy Soils
Conditions
Equivalent Fluid Unit Weight
(pcf)
Equivalent Fluid Unit Weight
(pcf)
Level Backfill 2:1 Sloped Backfill
Approved Imported Sandy Soils Approved Imported Sandy Soils Active 35 55
At-Rest 55 70
If the wall can yield enough to mobilize the full shear strength of the soil, it can be designed for “active” pressure. If the wall cannot yield under the applied load, the earth pressure will be higher. This would include 90-degree corners of retaining walls. Such walls should be designed for “at-rest.” The equivalent fluid pressure values assume free-draining conditions and a drainage system will be installed and maintained to prevent the build-up of hydrostatic pressures. If conditions other than those assumed above are anticipated, the equivalent fluid pressure values should be provided on an individual-case basis by the geotechnical engineer.

Retaining wall structures should be provided with appropriate drainage and appropriately waterproofed. To reduce, but not eliminate, saturation of near-surface (upper approximate 1- foot) soils in front of the retaining walls, the perforated subdrain pipe should be located as low as possible behind the retaining wall. The outlet pipe should be sloped to drain to a suitable outlet. In general, we do not recommend retaining wall outlet pipes be connected to area drains. If subdrains are connected to area drains, special care should be taken to maintain these drains. Typical conventional retaining wall drainage is shown on Figure 3. It should be noted that the recommended subdrain does not provide protection against seepage through the face of the wall and/or efflorescence. Waterproofing and outlet systems are not the purview of the geotechnical consultant.

Surcharge loading effects from any adjacent structures should be evaluated by the retaining wall designer. In general, structural loads within a 1:1 (horizontal to vertical) upward projection from the bottom of the proposed retaining wall footing will surcharge the proposed retaining wall. In addition to the recommended earth pressure, retaining walls adjacent to streets should be designed to resist a uniform lateral pressure of 85 pounds per square foot (psf) due to normal street vehicle traffic, if applicable. Uniform lateral surcharges may be estimated using the applicable coefficient of lateral earth pressure using a rectangular distribution. A factor of 0.45 and 0.3 may be used for at-rest and active conditions, respectively.

The retaining wall designer should contact the geotechnical consultant for any required geotechnical input in estimating surcharge loads.

If retaining walls greater than 6 feet in height are proposed, the retaining wall designer should contact the geotechnical engineer for specific seismic lateral earth pressure increments based on the configuration of the planned retaining wall structures.

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Soil bearing and lateral resistance (friction coefficient and passive resistance) are provided in Section 4.3. Earthwork considerations (temporary backcuts, backfill, compaction, etc.) for retaining walls are provided in Section 4.1 (Site Earthwork) and the subsequent earthwork related sub-sections.

4.5 Corrosivity to Concrete and Metal
Although not corrosion engineers (LGC Geotechnical is not a corrosion consultant), several governing agencies in Southern California require the geotechnical consultant to determine the corrosion potential of soils to buried concrete and metal facilities. We therefore present the results of our testing with regard to corrosion for the use of the client and other consultants, as they determine necessary.

Corrosion testing of near-surface bulk samples indicated a soluble sulfate content value of 66 ppm (less than 0.007 percent), a chloride content of 200 ppm, pH of 7.29, and a minimum resistivity of 1870 ohm-centimeters. Based on Caltrans Corrosion Guidelines (2021), soils are considered corrosive if the pH is 5.5 or less, or the chloride concentration is 500 ppm or greater, or the sulfate concentration is 2,000 ppm (0.2 percent) or greater. Based on the test results, soils are not considered corrosive using Caltrans criteria. Note that based on minimum resistivity the soils are considered severely corrosive to metallic improvements. If improvements that may be susceptible to corrosion are proposed, it is recommended that further evaluation by a corrosion engineer be performed.

Based on our laboratory test results of representative site soil samples, onsite soils should be considered as having a severity categorization of “not applicable” and are designated class “S0” per ACI 318, Table 19.3.1.1 with respect to sulfates. Concrete in direct contact with the onsite soils can be designed according to ACI 318, Table 19.3.2.1 using the “S0” sulfate classification.

Laboratory testing may need to be performed at the completion of grading by the project corrosion engineer to further evaluate the as-graded soil corrosivity characteristics.

Accordingly, revision of the corrosion potential may be needed, should future test results differ substantially from the conditions reported herein. The client and/or other members of the development team should consider this during the design and planning phase of the project and formulate an appropriate course of action.

4.6 Preliminary Asphalt Concrete Pavement Sections
For the purposes of these preliminary recommendations, we have selected a preliminary design R-value of 10 and calculated pavement sections for Traffic Indices of 5.0, 5.5 and 6.0. R-value testing of the street subgrade will need to be performed to confirm our preliminary testing results/assumptions once the streets have been graded to finish subgrade elevations and the final Traffic Index is determined by the Civil Engineer.

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TABLE 5
Preliminary Pavement Sections
Assumed Traffic Index 5.0 5.5 6.0
R ‐Value Subgrade 10 10 10
AC Thickness 4.0 inches 4.0 inches 5.0 inches
AB Thickness 6.5 inches 8.5 inches 8.5 inches
Due to anticipated construction traffic prior to the completion of the project, we recommend that the total thickness (base course and capping course) of AC be placed at essentially the same time. Construction traffic loading on only the base course of the AC will increase the potential for pavement distress. It should be noted that construction traffic such as concrete trucks will likely exceed traffic loading after completion of construction.

Increasing the thickness of asphalt or adding additional base material will reduce the likelihood of the pavement experiencing distress during its service life. The above recommendations are based on the assumption that proper maintenance and irrigation of the areas adjacent to the roadway will occur through the design life of the pavement. Failure to maintain a proper maintenance and/or irrigation program may jeopardize the integrity of the pavement.

Earthwork recommendations regarding aggregate base and subgrade are provided in the previous Section “Site Earthwork” and the related sub-sections of this report.

4.7 Nonstructural Concrete Flatwork
Nonstructural concrete flatwork (such as walkways, private drives, patio slabs, etc.) has a potential for cracking due to changes in soil volume related to soil-moisture fluctuations. To reduce the potential for excessive cracking and lifting, concrete may be designed in accordance with the minimum guidelines outlined in Table 6 below. These guidelines will reduce the potential for irregular cracking and promote cracking along construction joints but will not eliminate all cracking or lifting. Thickening the concrete and/or adding additional reinforcement will further reduce cosmetic distress.

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TABLE 6
Nonstructural Concrete Flatwork for Low Expansion Potential Homeowner
Sidewalks Private Drives Patios/
Entryways
City Sidewalk
Curb and
Gutters
Minimum
Thickness (in.) 4 (nominal) 4 (full) 4 (full) City/Agency Standard
Presoaking Wet down prior
to placing
Wet down prior to
placing
Wet down prior to
placing
City/Agency
Standard
Reinforcement  No. 3 at 24 inches
on centers
No. 3 at 24
inches on
centers
City/Agency
Standard
Thickened
Edge (in.)  8 x 8  City/Agency
Standard
Crack Control
Joints
Saw cut or deep
open tool joint
to a minimum of
1/3 the concrete
thickness
Saw cut or deep
open tool joint to a
minimum
of 1/3 the concrete
thickness
Saw cut or deep
open tool joint
to a minimum
of 1/3 the
concrete
thickness
City/Agency
Standard
Maximum
Joint Spacing 5 feet
10 feet or quarter
cut whichever is
closer
6 feet City/Agency
Standard
Aggregate
Base
Thickness (in.)
   City/Agency
Standard
To reduce the potential for driveways to separate from the garage slab, the builder may elect to install dowels to tie these two elements together. Similarly, future homeowners should consider the use of dowels to connect flatwork to the foundation.

4.8 Subsurface Water Infiltration
Recent regulatory changes have occurred that mandate that storm water be infiltrated below grade into subsurface soils rather than collected in a conventional storm drain system.

Typically, a combination of methods are implemented to reduce surface water runoff and increase infiltration including; permeable pavements/pavers for roadways and walkways, directing surface water runoff to grass-lined swales, retention areas, and/or drywells, etc.

It should be noted that collecting and concentrating surface water for the purpose of intentionally infiltrating below grade, conflicts with the geotechnical engineering objective of directing surface water away from slopes, structures and other improvements. The geotechnical stability and integrity of a site is reliant upon appropriately handling surface water. In general,

Page 1735 of 2604 ends

Project No. 23052‐01 Page 26 June 5, 2023
the vast majority of geotechnical distress issues are directly related to improper drainage. In general, distress in the form of movement of improvements could occur as a result of soil saturation and loss of soil support, expansion, internal soil erosion, collapse and/or settlement.

The results of our field infiltration testing indicate the observed 1-D infiltration rate for I-1 and I-2 (not including required factors of safety for design) were 0.005 and 0.007 inches per hour, respectively. The design infiltration rate is thereby equal to the Observed Infiltration Rate divided by the design factor of safety. The design factor of safety must be a minimum of 2.0 but may be increased at the discretion of the design engineer (County of San Diego, 2020).

Based on the results of field infiltration testing indicating very low infiltration rates, anticipated subsurface conditions consisting of compacted fill over very dense native materials, and hillside nature of the site, we strongly recommend against the intentional infiltration of stormwater into the subsurface soils.

4.9 Control of Surface Water and Drainage Control
From a geotechnical perspective, we recommend that compacted finished grade soils adjacent to proposed structures be sloped away from the proposed structures and towards an approved drainage device or unobstructed swale. Drainage swales, wherever feasible, should not be constructed within 5 feet of buildings. Where lot and building geometry necessitates that drainage swales be routed closer than 5 feet to structural foundations, we recommend the use of area drains together with drainage swales. Drainage swales used in conjunction with area drains should be designed by the project civil engineer so that a properly constructed and maintained system will prevent ponding within 5 feet of the foundation. Code compliance of grades is not the purview of the geotechnical consultant.

Planters with open bottoms adjacent to buildings should be avoided. Planters should not be designed adjacent to buildings unless provisions for drainage, such as catch basins, liners, and/or area drains, are made. Overwatering must be avoided.

4.10 Top of Slope Improvements
As with all top-of-slope improvements (fences, flatwork, etc.) some amount of future settlement and/or rotation should be expected. We recommend top-of-slope improvements be flexible (tube steel or vinyl fencing) or pavers instead of concrete flatwork. Alternatively, masonry fences or other rigid improvement can be constructed on deepened footings or if concrete is desired, inclusion of frequently spaced construction joints.

4.11 Geotechnical Plan Review
Project plans (grading, foundation, retaining wall, etc.) should be reviewed by this office prior to construction to verify that our geotechnical recommendations have been incorporated.

Additional or modified geotechnical recommendations may be required based on the proposed layout.

Page 1736 of 2604 ends

Project No. 23052‐01 Page 27 June 5, 2023

4.12 Geotechnical Observation and Testing
The recommendations provided in this report are based on limited subsurface observations and geotechnical analysis. The interpolated subsurface conditions should be checked in the field during construction by a representative of LGC Geotechnical. Geotechnical observation and testing is required per Section 1705 of the 2022 California Building Code (CBC).

Geotechnical observation and/or testing should be performed by LGC Geotechnical at the following stages:
 During grading (removal bottoms, fill placement, etc.);  During retaining wall backfill and compaction;
 During utility trench backfill and compaction;
 After presoaking building pad and other concrete-flatwork subgrades, and prior to placement of aggregate base or concrete;
 Preparation of pavement subgrade and placement of aggregate base;  After building and wall footing excavation and prior to placement of steel reinforcement and/or concrete; and
 When any unusual soil conditions are encountered during any construction operation subsequent to issuance of this report.

Page 1737 of 2604 ends

Project No. 23052‐01 Page 28 June 5, 2023

5.0 LIMITATIONS
Our services were performed using the degree of care and skill ordinarily exercised, under similar circumstances, by reputable soils engineers and geologists practicing in this or similar localities. No other warranty, expressed or implied, is made as to the conclusions and professional advice included in this report.

This report is based on data obtained from limited observations of the site, which have been extrapolated to characterize the site. While the scope of services performed is considered suitable to adequately characterize the site geotechnical conditions relative to the proposed development, no practical evaluation can completely eliminate uncertainty regarding the anticipated geotechnical conditions in connection with a subject site. Variations may exist and conditions not observed or described in this report may be encountered during grading and construction.

This report is issued with the understanding that it is the responsibility of the owner, or of his/her representative, to ensure that the information and recommendations contained herein are brought to the attention of the other consultants (at a minimum the civil engineer, structural engineer, landscape architect) and incorporated into their plans. The contractor should properly implement the recommendations during construction and notify the owner if they consider any of the recommendations presented herein to be unsafe, or unsuitable.

The findings of this report are valid as of the present date. However, changes in the conditions of a site can and do occur with the passage of time, whether they be due to natural processes or the works of man on this or adjacent properties. The findings, conclusions, and recommendations presented in this report can be relied upon only if LGC Geotechnical has the opportunity to observe the subsurface conditions during grading and construction of the project, in order to confirm that our preliminary findings are representative for the site. This report is intended exclusively for use by the client, any use of or reliance on this report by a third party shall be at such party’s sole risk.

In addition, changes in applicable or appropriate standards may occur, whether they result from legislation or the broadening of knowledge. Accordingly, the findings of this report may be invalidated wholly or partially by changes outside our control. Therefore, this report is subject to review and modification.

Page 1738 of 2604 ends

Page 1739 of 2604 ends

I-2
T.D. = 10'
I-1
T.D. = 10'
HS-3
T.D. = 6.5'
HS-1
T.D. = 14'
HS-2
T.D. = 10'
LEGEND
Approximate Location of Hollow-Stem Boring by
LGC Geotechnical, With Total Depth in Feet
Approximate Location of Hollow-Stem Infiltration
Boring by LGC Geotechnical, With Total Depth in Feet
Approximate Limits of Property
Estimated Minimum Removal Depth Below
Existing Grade, In Feet
I-2
T.D. = 10'
HS-3
T.D. = 6.5'

7.5'
5'
5'
5'

7.5'
See Section 4.1.1 For Potential
Toe of Slope Keyway

7.5'
-10'
Figure 2
Geotechnical Map ENG. / GEOL.

PROJECT NO.

PROJECT NAME
SCALE
DATE
1" = 60'
June 2023
Meritage - 9407 Jericho Road, La Mesa
DJB
23052-01 LGC Geotechnical, Inc.
131 Calle Iglesia, Ste. 200
San Clemente, CA 92672
TEL (949) 369-6141 FAX (949) 369-6142

Page 1740 of 2604 ends

Page 1741 of 2604 ends

4 INCH DIAMETER, SCHEDULE 40 PERFORATED

PVC PIPE TO FLOW TO DRAINAGE DEVICE PER

PROJECT CIVIL ENGINEER

COMPACTED SAND BACKFILL
(EXPANSION INDEX £ 20,
MAXIMUM 35% FINES)

NATIVE BACKFILL COMPACTED

PER REPORT
MINIMUM 1 CUBIC FOOT PER LINEAR FOOT

BURRITO TYPE SUBDRAIN, CONSISTING OF
3/4 INCH CRUSHED ROCK WRAPPED IN
MIRAFI 140N OR APPROVED EQUIVALENT

FOOTING/WALL PER DESIGN ENGINEER

WATER PROOFING PER DESIGN ENGINEER
12" MINIMUM
18" MAXIMUM

BACKCUT PER OSHA

EXTENT OF REQUIRED IMPORTED SAND BACKFILL, MINIMUM
HEEL WIDTH OR H/2 WHICH EVER IS GREATER WALL HEIGHT, H
NOTE:

PLACEMENT OF SUBDRAIN

AT BASE OF WALL WILL NOT

PREVENT SATURATION OF SOILS

BELOW AND / OR IN FRONT OF WALL
FIGURE 3
Retaining Wall
Backfill Detail
DATE June 2023
ENG. / GEOL.

PROJECT NO.

PROJECT NAME
SCALE
DJB
Not to Scale
Meritage - 9407 Jericho Road, La Mesa
23052-01

Page 1742 of 2604 ends

Page 1743 of 2604 ends

Appendix A
References

Page 1744 of 2604 ends

Project No. 23052‐01 Page 1 June 5, 2023

APPENDIX A
References
American Concrete Institute, 2019, Building Code Requirements for Structural Concrete (ACI 318-19) and Commentary (ACI 318R-19).

American Society of Civil Engineers (ASCE), 2017, Minimum Design Loads for Buildings and Other Structures, ASCE/SEI 7-16, Third Printing, 2017.

ASTM International, Annual Book of ASTM Standards, Volume 04.08.

California Building Standards Commission, 2022, California Building Code, California Code of Regulations Title 24, Volumes 1 and 2, dated July 2022.

California Department of Conservation, Division of Mines and Geology, 1997, Guidelines for Evaluating and Mitigating Seismic Hazards in California, CDMG Special Publication 117. ________, 2000, Digital Images of Official Maps of Alquist-Priolo Earthquake Fault Zones of California, Southern Region, CDMG CD 2000-03.

California Department of Transportation (Caltrans), 2021, Corrosion Guidelines, Version 3.2, dated May 2021.
________, 2017, Highway Design Manual, Updated November 20, 2017.

California Geological Survey (CGS), 2008, California Geological Society Special Publication 117A:

Guidelines for Evaluating and Mitigating Seismic Hazards in California. ________, 2018, Special Publication 42: Earthquake Fault Zones, A Guide for Government Agencies, Property Owners/Developers, and Geoscience Practitioners for Assessing Fault Rupture Hazards in California, Revised 2018.

County of San Diego, 2020, County of San Diego BMP Design Manual, dated September 15, 2020.

Structural Engineers Association of California (SEAOC), 2023, U.S. Seismic Design Maps, Retrieved May 11, 2023, from https://seismicmaps.org/.

United States Geological Survey (USGS), 2014, Unified Hazard Tool, Dynamic: Conterminous U.S. 2014 (v4.2.0), Retrieved May 11, 2023, from
https://earthquake.usgs.gov/hazards/interactive/.
________, 2002, Geologic Map of the El Cajon 7.5’ Quadrangle, San Diego County, California, by Siang S. Tan, dated 2002.

Page 1745 of 2604 ends

Appendix B
Boring & Geotechnical Trench Logs

Page 1746 of 2604 ends

THIS SUMMARY APPLIES ONLY AT THE LOCATION OF THIS BORING AND AT THE TIME OF DRILLING. SUBSURFACE CONDITIONS MAY DIFFER AT OTHER LOCATIONS AND MAY CHANGE AT THIS LOCATION WITH THE PASSAGE OF TIME. THE DATA PRESENTED IS A SIMPLIFICATION OF THE ACTUAL CONDITIONS ENCOUNTERED. THE DESCRIPTIONS

PROVIDED ARE QUALITATIVE FIELD DESCRIPTIONS

AND ARE NOT BASED ON QUANTITATIVE
ENGINEERING ANALYSIS. CN CONSOLIDATION

CR CORROSION

AL ATTERBERG LIMITS CO COLLAPSE/SWELL RV R-VALUE
-#200 % PASSING # 200 SIEVE

DIRECT SHEAR MAXIMUM DENSITY

SIEVE ANALYSIS

SIEVE AND HYDROMETER

EXPANSION INDEX
TEST TYPES: DSMD
SA
S&H
EI
SAMPLE TYPES: B BULK SAMPLE R RING SAMPLE (CA Modified Sampler) G GRAB SAMPLE

SPT STANDARD PENETRATION

TEST SAMPLE GROUNDWATER TABLE
30 25
20 15
10 5
0 Elevation (ft) Depth (ft) Graphic Log Sample Number Blow Count Dry Density (pcf) Moisture (%) USCS Symbol DESCRIPTION Type of Test Hole Diameter:

Hole Location: See Geotechnical Map
Drop:

Type of Rig:

Project Number:

Elevation of Top of Hole: Drive Weight:

Drilling Company:

Project Name:

Date:
640
635
630
625
620
615
Geotechnical Boring Log Borehole HS-1
3/28/2023
~645' MSL
8"
Truck Mounted Rig
30"
140 pounds
Martini Drilling
Meritage - Jericho Road, La Mesa
23052-01
Logged By JMN
Sampled By JMN
Checked By DJB

Page 1 of 1 ends

@0' to 7.5' - Older Artificial Fill (afo):
@ 0' - Sandy CLAY: dark brown, slight moist; vegetation -#200
MD
EI
R-1 CR 5
5 3
106.9 9.6 @ 2.5' - Sandy CLAY with Gravel: brown, slightly moist, medium stiff
R-2 2
2 2
100.5 12.2 CL-SC @ 5' - Sandy CLAY to Clayey SAND: grayish brown, moist, soft/very loose
R-3 3
7 11

14.9 CL
@7.5' to T.D. - Mission Valley Formation (Tmv):
@ 7.5' - Sandy CLAY with Gravel: brown, moist, stiff CO R-4 44
50/5" 4.2 GC @ 10' - Clayey Gravel with SAND: light brown, slightly moist, very dense
Total Depth = 14'
Groundwater Not Encountered
Backfilled with Cuttings on 3/28/2023 B-1 Last Edited: 3/30/2023 107.2
CL
@ 14' - Auger Refusal

Page 1747 of 2604 ends

PROVIDED ARE QUALITATIVE FIELD DESCRIPTIONS

AND ARE NOT BASED ON QUANTITATIVE
ENGINEERING ANALYSIS. CN CONSOLIDATION

CR CORROSION

AL ATTERBERG LIMITS CO COLLAPSE/SWELL RV R-VALUE
-#200 % PASSING # 200 SIEVE

DIRECT SHEAR MAXIMUM DENSITY

SIEVE ANALYSIS

SIEVE AND HYDROMETER

EXPANSION INDEX
TEST TYPES: DSMD
SA
S&H
EI
SAMPLE TYPES: B BULK SAMPLE R RING SAMPLE (CA Modified Sampler) G GRAB SAMPLE

SPT STANDARD PENETRATION

TEST SAMPLE GROUNDWATER TABLE
30 25
20 15
10 5
0 Elevation (ft) Depth (ft) Graphic Log Sample Number Blow Count Dry Density (pcf) Moisture (%) USCS Symbol DESCRIPTION Type of Test Hole Diameter:

Hole Location: See Geotechnical Map
Drop:

Type of Rig:

Project Number:

Elevation of Top of Hole: Drive Weight:

Drilling Company:

Project Name:

Date:
650
645
640
635
630
625
Geotechnical Boring Log Borehole HS-2
3/28/2023
~652' MSL
8"
Truck Mounted Rig
30"
140 pounds
Martini Drilling
Meritage - Jericho Road, La Mesa
23052-01
Logged By JMN
Sampled By JMN
Checked By DJB

Page 1 of 1 ends

@0' to 2.5' - Older Artificial Fill (afo):
@ 0' - Clayey SAND: brown, dry; vegetation
-#200
MD
EI
R-1 50/6" 7.1 CL
@2.5' to T.D. - Mission Valley Formation (Tmv):
@ 2.5' - Gravelly CLAY with Sand: reddish brown,
slightly moist, hard
R-2 50/3" @ 5' - No Recovery
R-3 50/5" 8.7 SC @ 7.5' - Clayey SAND with Gravel: light brown, moist, very dense
R-4 50/1" 112.7 7.3 @ 10' - Clayey SAND with Gravel: light brown, moist, very dense; auger refusal
Total Depth = 10'
Groundwater Not Encountered
Backfilled with Cuttings on 3/28/2023 B-1 Last Edited: 3/30/2023

Page 1748 of 2604 ends

PROVIDED ARE QUALITATIVE FIELD DESCRIPTIONS

AND ARE NOT BASED ON QUANTITATIVE
ENGINEERING ANALYSIS. CN CONSOLIDATION

CR CORROSION

AL ATTERBERG LIMITS CO COLLAPSE/SWELL RV R-VALUE
-#200 % PASSING # 200 SIEVE

DIRECT SHEAR MAXIMUM DENSITY

SIEVE ANALYSIS

SIEVE AND HYDROMETER

EXPANSION INDEX
TEST TYPES: DSMD
SA
S&H
EI
SAMPLE TYPES: B BULK SAMPLE R RING SAMPLE (CA Modified Sampler) G GRAB SAMPLE

SPT STANDARD PENETRATION

TEST SAMPLE GROUNDWATER TABLE
30 25
20 15
10 5
0 Elevation (ft) Depth (ft) Graphic Log Sample Number Blow Count Dry Density (pcf) Moisture (%) USCS Symbol DESCRIPTION Type of Test Hole Diameter:

Hole Location: See Geotechnical Map
Drop:

Type of Rig:

Project Number:

Elevation of Top of Hole: Drive Weight:

Drilling Company:

Project Name:

Date:
650
645
640
635
630
625
Geotechnical Boring Log Borehole HS-3
3/28/2023
~652' MSL
8"
Truck Mounted Rig
30"
140 pounds
Martini Drilling
Meritage - Jericho Road, La Mesa
23052-01
Logged By JMN
Sampled By JMN
Checked By DJB

Page 1 of 1 ends

@0' to 2.5' - Older Artificial Fill (afo):
@ 0' - Clayey SAND: light brown, slightly moist;
vegetation
R-1 10
13 14

91.8 14.1 @2.5' to T.D. - Mission Valley Formation (Tmv):
@ 2.5' - Clayey SAND: brown, very moist, medium
dense
R-2 9
11 43
@ 5' - No Recovery
@6.5' - Auger Refusal
Total Depth = 6.5'
Groundwater Not Encountered
Backfilled with Cuttings on 3/28/2023 B-1 Last Edited: 3/30/2023 SC

Page 1749 of 2604 ends

PROVIDED ARE QUALITATIVE FIELD DESCRIPTIONS

AND ARE NOT BASED ON QUANTITATIVE
ENGINEERING ANALYSIS. CN CONSOLIDATION

CR CORROSION

AL ATTERBERG LIMITS CO COLLAPSE/SWELL RV R-VALUE
-#200 % PASSING # 200 SIEVE

DIRECT SHEAR MAXIMUM DENSITY

SIEVE ANALYSIS

SIEVE AND HYDROMETER

EXPANSION INDEX
TEST TYPES: DSMD
SA
S&H
EI
SAMPLE TYPES: B BULK SAMPLE R RING SAMPLE (CA Modified Sampler) G GRAB SAMPLE

SPT STANDARD PENETRATION

TEST SAMPLE GROUNDWATER TABLE
30 25
20 15
10 5
0 Elevation (ft) Depth (ft) Graphic Log Sample Number Blow Count Dry Density (pcf) Moisture (%) USCS Symbol DESCRIPTION Type of Test Hole Diameter:

Hole Location: See Geotechnical Map
Drop:

Type of Rig:

Project Number:

Elevation of Top of Hole: Drive Weight:

Drilling Company:

Project Name:

Date:
645
640
635
630
625
620
Geotechnical Boring Log Borehole I-1
3/28/2023
~647' MSL
8"
Truck Mounted Rig
30"
140 pounds
Martini Drilling
Meritage - Jericho Road, La Mesa
23052-01
Logged By JMN
Sampled By JMN
Checked By DJB

Page 1 of 1 ends

@0' to 2.5' - Older Artificial Fill (afo):
@ 0' - 5" of Concrete Pavement
SPT-1 37
50/5" 11.4 CL
@2.5' to T.D. - Mission Valley Formation (Tmv):
@ 2.5' - Sandy CLAY: brown, slightly moist, hard
R-2 15
50/4" 109.2 7.7 SC @ 5' - Clayey SAND with Gravel: light brown, moist, very dense
SPT-2 43
28 41

10.7 @ 8.5' - Clayey SAND: light brown, moist, very dense Total Depth = 10'
Groundwater Not Encountered
3'' Perforated Pipe with Filter Sock Installed
Surrounded by Gravel, and Presoaked on 3/28/23
Backfilled with Cuttings and Capped with Concrete on
3/29/2023 Last Edited: 3/30/2023

Page 1750 of 2604 ends

PROVIDED ARE QUALITATIVE FIELD DESCRIPTIONS

AND ARE NOT BASED ON QUANTITATIVE
ENGINEERING ANALYSIS. CN CONSOLIDATION

CR CORROSION

AL ATTERBERG LIMITS CO COLLAPSE/SWELL RV R-VALUE
-#200 % PASSING # 200 SIEVE

DIRECT SHEAR MAXIMUM DENSITY

SIEVE ANALYSIS

SIEVE AND HYDROMETER

EXPANSION INDEX
TEST TYPES: DSMD
SA
S&H
EI
SAMPLE TYPES: B BULK SAMPLE R RING SAMPLE (CA Modified Sampler) G GRAB SAMPLE

SPT STANDARD PENETRATION

TEST SAMPLE GROUNDWATER TABLE
30 25
20 15
10 5
0 Elevation (ft) Depth (ft) Graphic Log Sample Number Blow Count Dry Density (pcf) Moisture (%) USCS Symbol DESCRIPTION Type of Test Hole Diameter:

Hole Location: See Geotechnical Map
Drop:

Type of Rig:

Project Number:

Elevation of Top of Hole: Drive Weight:

Drilling Company:

Project Name:

Date:
650
645
640
635
630
625
Geotechnical Boring Log Borehole I-2
3/28/2023
~651' MSL
8"
Truck Mounted Rig
30"
140 pounds
Martini Drilling
Meritage - Jericho Road, La Mesa
23052-01
Logged By JMN
Sampled By JMN
Checked By DJB

Page 1 of 1 ends

@0' to 7.5' - Older Artificial Fill (afo):
@ 0' - 6" of Concrete Pavement
R-1 6
4 4
102.9 22.8 CL @ 5' - CLAY with Sand: brown,very moist, medium stiff CO R-2 42
50/2" 7.1 @ 10' - Gravelly CLAY with Sand: light yellowish brown, slightly moist, hard
Total Depth = 10'
Groundwater Not Encountered
3'' Perforated Pipe with Filter Sock Installed
Surrounded by Gravel, and Presoaked on 3/28/23
Backfilled with Cuttings and Capped with Concrete on
3/29/2023 Last Edited: 3/30/2023
@7.5' to T.D. - Mission Valley Formation (Tmv):

Page 1751 of 2604 ends

Appendix C
Laboratory Test Results

Page 1752 of 2604 ends

Project No. 23052‐01 C‐1 June 2023

APPENDIX C
Laboratory Testing Procedures and Test Results
The laboratory testing program was formulated towards providing data relating to the relevant engineering properties of the soils with respect to residential construction. Samples considered representative of site conditions were tested in general accordance with American Society for Testing and Materials (ASTM) procedure and/or California Test Methods (CTM), where applicable.

The following summary is a brief outline of the test type and a table summarizing the test results.

Moisture and Density Determination Tests: Moisture content (ASTM D2216) and dry density determinations (ASTM D2937) were performed on relatively undisturbed samples obtained from the test borings and/or trenches. The results of these tests are presented in the boring logs. Where applicable, only moisture content was determined from undisturbed or disturbed samples.

Expansion Index: The expansion potential of selected samples was evaluated by the Expansion Index Test, Standard ASTM D4829. Specimens are molded under a given compactive energy to approximately the optimum moisture content and approximately 50 percent saturation or approximately 90 percent relative compaction. The prepared 1-inch-thick by 4-inch-diameter specimens are loaded to an equivalent 144 psf surcharge and are inundated with tap water until volumetric equilibrium is reached. The results of these tests are presented in the table below.

Sample
Location
Expansion
Index
Expansion
Potential*
HS-1 @ 0-5 feet 31 Low
HS-2 @ 0-5 feet 23 Low
* ASTM D4829
Grain Size Distribution/Fines Content: Representative samples were dried, weighed and soaked in water until individual soil particles were separated (per ASTM D421) and then washed on a No. 200 sieve (ASTM D1140). Where applicable, the portion retained on the No. 200 sieve and dried and then sieved on a U.S. Standard brass sieve set in accordance with ASTM D6913 (sieve).

Sample
Location
Description % Passing #
200 Sieve
HS-1 @ 0-5 feet Clayey Sand with Gravel 32
HS-2 @ 0-5 feet Clayey Sand with Gravel 26

Page 1753 of 2604 ends

APPENDIX C (Cont’d)
Laboratory Testing Procedures and Test Results
Project No. 23052‐01 C‐2 June 2023
Collapse/Swell Potential: Two collapse tests were performed per ASTM D4546. Samples (2.4 inches in diameter and 1-inch in height) were placed in a consolidometer and loaded to their approximate in-situ effective stress. The results are in this appendix.

Maximum Density Tests: The maximum dry density and optimum moisture content of typical materials were determined in accordance with ASTM D1557. The results of these tests are presented in the table below:

Sample
Location Sample Description
Maximum
Dry Density
(pcf)
Optimum Moisture
Content (%)
*HS-1 @ 0-5 feet Clayey Sand with Gravel 124.5 10.5
**HS-2 @ 0-5 feet Clayey Sand with Gravel 129.5 7.5
*Note: This max dry density result is based on a rock correction with approximately 20% retained on the No. 4 sieve.
**Note: This max dry density result is based on a rock correction with approximately 24% retained on the No. 4 sieve.

Chloride Content: Chloride content was tested in accordance with Caltrans Test Method (CTM) 422. The results are presented below.

Sample Location Chloride Content, ppm
HS-1 @ 0-5 feet 200
Soluble Sulfates: The soluble sulfate contents of selected samples were determined by standard geochemical methods (CTM 417). The soluble sulfate content is used to determine the appropriate cement type and maximum water-cement ratios. The test results are presented in the table below.

Sample
Location
Sulfate Content
(ppm)
Sulfate Exposure
Class *
HS-1 @ 0-5 feet 66 S0
*Based on ACI 318R-14, Table 19.3.1.1

Page 1754 of 2604 ends

APPENDIX C (Cont’d)
Laboratory Testing Procedures and Test Results
Project No. 23052‐01 C‐3 June 2023
Minimum Resistivity and pH Tests: Minimum resistivity and pH tests were performed in general accordance with CTM 643 and standard geochemical methods. The results are presented in the table below.

Sample
Location pH Minimum Resistivity
(ohms‐cm)
HS-1 @ 0-5 feet 7.29 1870

Page 1755 of 2604 ends

Project Name: Tested By: G. Bathala Date: 04/04/23
Project No.: Checked By: J. Ward Date: 04/13/23
Boring No.: HS-1 Sample Type: Ring
Sample No.: R-3 Depth (ft.) 7.5
Sample Description: Strong brown sandy lean clay with gravel s(CL)g Initial Dry Density (pcf): 97.7 Final Dry Density (pcf): 99.4 Initial Moisture (%): 14.91 Final Moisture (%) : 20.2
Initial Length (in.): 1.0000 Initial Void ratio: 0.7258 Initial Dial Reading: 0.0460 Specific Gravity(assumed): 2.70 Diameter(in): 2.415 Initial Saturation (%) 55.5

0.100 0.9987 0.00 -0.13 -0.13

1.000 0.9851 0.16 -1.49 -1.33
H2O 0.9845 0.16 -1.55 -1.39
Percent Swell (+) / Settlement (-) After Inundation = -0.06 Load
Compliance
(%)
Apparent
Thickness
(in)

ONE-DIMENSIONAL SWELL OR SETTLEMENT

POTENTIAL OF COHESIVE SOILS
ASTM D 4546
Corrected
Deformation
(%)
Meritage - 9407 Jericho Road
23052-01

0.7018

0.0473

0.0609

0.0615
Pressure (p)
(ksf)

0.7235

0.7028
Final Reading
(in) Void Ratio
Swell (+)
Settlement (-)
% of Sample
Thickness

0.7000

0.7050

0.7100

0.7150

0.7200

0.7250

0.100 1.000 10.000
Void Ratio
Log Pressure (ksf)
Void Ratio - Log Pressure Curve
Inundate with
Tap water
Swell or Settlement HS-1, R-3 @ 7.5

Page 1756 of 2604 ends

Project Name: Tested By: G. Bathala Date: 04/04/23
Project No.: Checked By: J. Ward Date: 04/13/23
Boring No.: I-2 Sample Type: Ring
Sample No.: R-1 Depth (ft.) 5.0
Sample Description: Strong brown lean clay with sand (CL)s Initial Dry Density (pcf): 103.8 Final Dry Density (pcf): 110.2 Initial Moisture (%): 22.75 Final Moisture (%) : 17.8
Initial Length (in.): 1.0000 Initial Void ratio: 0.6240 Initial Dial Reading: 0.1193 Specific Gravity(assumed): 2.70 Diameter(in): 2.415 Initial Saturation (%) 98.5

0.100 0.9965 0.00 -0.35 -0.35

1.000 0.9651 0.16 -3.49 -3.33
H2O 0.9433 0.16 -5.67 -5.51
Percent Swell (+) / Settlement (-) After Inundation = -2.26 Load
Compliance
(%)
Apparent
Thickness
(in)

ONE-DIMENSIONAL SWELL OR SETTLEMENT

POTENTIAL OF COHESIVE SOILS
ASTM D 4546
Corrected
Deformation
(%)
Meritage - 9407 Jericho Road
23052-01

0.5345

0.1228

0.1542

0.1760
Pressure (p)
(ksf)

0.6183

0.5699
Final Reading
(in) Void Ratio
Swell (+)
Settlement (-)
% of Sample
Thickness

0.5300

0.5400

0.5500

0.5600

0.5700

0.5800

0.5900

0.6000

0.6100

0.6200

0.6300

0.100 1.000 10.000
Void Ratio
Log Pressure (ksf)
Void Ratio - Log Pressure Curve
Inundate with
Tap water
Swell or Settlement I-2, R-1 @ 5

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Appendix D
Infiltration Test Data

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Boring Number:

Test hole dimensions (if circular)
10 8
3 8.4 ft
Pre‐Test (Sandy Soil Criteria)*
1 9:14 9:39 25.0 2.05 2.06 0.01
2 9:39 10:04 25.0 2.06 2.08 0.02
Main Test Data
1 10:04 10:34 30.0 2.08 2.09 0.01 0.2 0.005
2 10:34 11:04 30.0 2.09 2.10 0.01 0.2 0.005
3 11:04 11:34 30.0 2.10 2.12 0.02 0.5 0.010
4 11:34 12:04 30.0 2.12 2.13 0.01 0.2 0.005
5 12:04 12:34 30.0 2.13 2.14 0.01 0.2 0.005
6 12:34 13:04 30.0 2.14 2.16 0.02 0.5 0.010
7 13:04 13:34 30.0 2.16 2.17 0.01 0.2 0.005
8 13:34 14:04 30.0 2.17 2.18 0.01 0.2 0.005
9 14:04 14:34 30.0 2.18 2.19 0.01 0.2 0.005
10 14:34 15:04 30.0 2.19 2.20 0.01 0.2 0.005
11 15:04 15:34 30.0 2.20 2.21 0.01 0.2 0.005
12 15:34 16:04 30.0 2.21 2.22 0.01 0.2 0.005
Factor of Safety See Report
See Report
Sketch: Notes:

Time Interval
(min)
Pit Length (feet):

Initial Depth to
Water, Do (feet)
Final Depth
to Water, Df
(feet)
Minimum test Head (Do):

Pipe Diameter (inches):

Boring Depth ‐ (5 x Boring Radius) (What the sounder tape should read) (Shallow) The value on the sounder tape should be close to this value during testing for DEEP testing fill to 4 feet below top of hole

0.005
Calculated Infiltration Rate (With Factor of Safety)
Trial No. Time Interval, t
(min)
Start Time
(24:HR)
Stop Time
(24:HR)
Total Change
in Water Level
(feet)
Calculated Infiltration Rate (No factors of safety)
Change in
Water Level,
D (feet)
Meritage ‐ La Mesa
Spreadsheet Revised on: 2/6/2017
Calculated
Infiltration
Rate(in/hr)
*If two consecutive measurements show that six inches of water seeps away in less than 25 minutes, the test shall be run for an additional hour with measurements taken every 10 minutes. Otherwise, pre‐soak (fill) overnight, and then obtain at least twelve measurements per hole over at least six hours (approximately 30 minute intervals) with a precision of at least 0.25 inches
Start Time
(24:HR)
Stop Time
(24:HR)
Initial Depth to
Water (feet)
Final Depth
to Water
(feet)
Trial No.

Based on Guidelines from: San Diego County 05/19/2011
Infiltration Test Data Sheet
23052‐01
Boring Diameter (inches):

I‐1
LGC Geotechnical, Inc
131 Calle Iglesia Suite 200, San Clemente, CA 92672 tel. (949) 369‐6141 Project Name:
3/29/2023
Boring Depth (feet)*:

Project Number:

Test pit dimensions (if rectangular)
Date:
*measured at time of test
Pit Breadth (feet):

Pit Depth (feet):

Percolation
Rate
(in/hr)
Greater Than or Equal to

0.5 feet (yes/no)
No
No

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Boring Number:

Test hole dimensions (if circular)
10 8
3 8.4 ft
Pre‐Test (Sandy Soil Criteria)*
1 9:10 9:35 25.0 4.28 4.29 0.01
2 9:35 10:00 25.0 4.29 4.3 0.01
Main Test Data
1 10:00 10:30 30.0 4.30 4.30 0.00 0.0 0.000
2 10:30 11:00 30.0 4.30 4.30 0.00 0.0 0.000
3 11:00 11:30 30.0 4.30 4.30 0.00 0.0 0.000
4 11:30 12:00 30.0 4.30 4.31 0.01 0.2 0.007
5 12:00 12:30 30.0 4.31 4.31 0.00 0.0 0.000
6 12:30 13:00 30.0 4.31 4.31 0.00 0.0 0.000
7 13:00 13:30 30.0 4.31 4.32 0.01 0.2 0.007
8 13:30 14:00 30.0 4.32 4.32 0.00 0.0 0.000
9 14:00 14:30 30.0 4.32 4.32 0.00 0.0 0.000
10 14:30 15:00 30.0 4.32 4.32 0.00 0.0 0.000
11 15:00 15:30 30.0 4.32 4.32 0.00 0.0 0.000
12 15:30 16:00 30.0 4.32 4.33 0.01 0.2 0.007
Factor of Safety See Report
See Report
Sketch: Notes:

Calculated Infiltration Rate (With Factor of Safety)
Based on Guidelines from: San Diego County 05/19/2011
Spreadsheet Revised on: 2/6/2017
Final Depth
to Water, Df
(feet)
Change in
Water Level,
D (feet)
Percolation
Rate
(in/hr)
Calculated
Infiltration
Rate(in/hr)
Calculated Infiltration Rate (No factors of safety) 0.007 Total Change
in Water Level
(feet)
Greater Than or Equal to

0.5 feet (yes/no)
No
No
*If two consecutive measurements show that six inches of water seeps away in less than 25 minutes, the test shall be run for an additional hour with measurements taken every 10 minutes. Otherwise, pre‐soak (fill) overnight, and then obtain at least twelve measurements per hole over at least six hours (approximately 30 minute intervals) with a precision of at least 0.25 inches
Trial No.

Start Time
(24:HR)
Stop Time
(24:HR)
Time Interval, t
(min)
Initial Depth to
Water, Do (feet)
Trial No.

Start Time
(24:HR)
Stop Time
(24:HR)
Time Interval
(min)
Initial Depth to
Water (feet)
Final Depth
to Water
(feet)
Pipe Diameter (inches): Pit Breadth (feet): *measured at time of test Minimum test Head (Do):

Boring Depth ‐ (5 x Boring Radius)
(Shallow) The value on the sounder tape should be close to this value during testing for DEEP testing fill to 4 feet below top of hole
(What the sounder tape should read)
Boring Depth (feet)*: Pit Depth (feet):

Boring Diameter (inches): Pit Length (feet):

Date: 3/29/2023
I‐2
Test pit dimensions (if rectangular)
Infiltration Test Data Sheet
LGC Geotechnical, Inc
131 Calle Iglesia Suite 200, San Clemente, CA 92672 tel. (949) 369‐6141 Project Name: Meritage ‐ La Mesa
Project Number: 23052‐01

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Appendix E
General Earthwork and Grading
Specifications for Rough Grading

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General Earthwork and Grading Specifications for Rough Grading

1.0 General

1.1 Intent
These General Earthwork and Grading Specifications are for the grading and earthwork shown on the approved grading plan(s) and/or indicated in the geotechnical report(s). These Specifications are a part of the recommendations contained in the geotechnical report(s). In case of conflict, the specific recommendations in the geotechnical report shall supersede these more general Specifications. Observations of the earthwork by the project Geotechnical Consultant during the course of grading may result in new or revised recommendations that could supersede these specifications or the recommendations in the geotechnical report(s).

1.2 The Geotechnical Consultant of Record
Prior to commencement of work, the owner shall employ a qualified Geotechnical Consultant of Record (Geotechnical Consultant). The Geotechnical Consultant shall be responsible for reviewing the approved geotechnical report(s) and accepting the adequacy of the preliminary geotechnical findings, conclusions, and recommendations prior to the commencement of the grading.

Prior to commencement of grading, the Geotechnical Consultant shall review the "work plan" prepared by the Earthwork Contractor (Contractor) and schedule sufficient personnel to perform the appropriate level of observation, mapping, and compaction testing.

During the grading and earthwork operations, the Geotechnical Consultant shall observe, map, and document the subsurface exposures to verify the geotechnical design assumptions. If the observed conditions are found to be significantly different than the interpreted assumptions during the design phase, the Geotechnical Consultant shall inform the owner, recommend appropriate changes in design to accommodate the observed conditions, and notify the review agency where required.

The Geotechnical Consultant shall observe the moisture-conditioning and processing of the subgrade and fill materials and perform relative compaction testing of fill to confirm that the attained level of compaction is being accomplished as specified. The Geotechnical Consultant shall provide the test results to the owner and the Contractor on a routine and frequent basis.

1.3 The Earthwork Contractor
The Earthwork Contractor (Contractor) shall be qualified, experienced, and knowledgeable in earthwork logistics, preparation and processing of ground to receive fill, moistureconditioning and processing of fill, and compacting fill. The Contractor shall review and accept the plans, geotechnical report(s), and these Specifications prior to commencement of grading. The Contractor shall be solely responsible for performing the grading in accordance with the project plans and specifications. The Contractor shall prepare and submit to the owner and the Geotechnical Consultant a work plan that indicates the sequence of earthwork grading, the number of “equipment” of work and the estimated quantities of daily earthwork General Earthwork and Grading Specifications for Rough Grading Page 1

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contemplated for the site prior to commencement of grading. The Contractor shall inform the owner and the
Geotechnical Consultant of changes in work schedules and updates to the work plan at least 24 hours in advance of such changes so that appropriate personnel will be available for observation and testing. The Contractor shall not assume that the Geotechnical Consultant is aware of all grading operations.

The Contractor shall have the sole responsibility to provide adequate equipment and methods to accomplish the earthwork in accordance with the applicable grading codes and agency ordinances, these Specifications, and the recommendations in the approved geotechnical report(s) and grading plan(s). If, in the opinion of the Geotechnical Consultant, unsatisfactory conditions, such as unsuitable soil, improper moisture condition, inadequate compaction, insufficient buttress key size, adverse weather, etc., are resulting in a quality of work less than required in these specifications, the Geotechnical Consultant shall reject the work and may recommend to the owner that construction be stopped until the conditions are rectified. It is the contractor’s sole responsibility to provide proper fill compaction.

2.0 Preparation of Areas to be Filled

2.1 Clearing and Grubbing
Vegetation, such as brush, grass, roots, and other deleterious material shall be sufficiently removed and properly disposed of in a method acceptable to the owner, governing agencies, and the Geotechnical Consultant.

The Geotechnical Consultant shall evaluate the extent of these removals depending on specific site conditions. Earth fill material shall not contain more than 1 percent of organic materials (by volume). Nesting of the organic materials shall not be allowed.

If potentially hazardous materials are encountered, the Contractor shall stop work in the affected area, and a hazardous material specialist shall be informed immediately for proper evaluation and handling of these materials prior to continuing to work in that area.

As presently defined by the State of California, most refined petroleum products (gasoline, diesel fuel, motor oil, grease, coolant, etc.) have chemical constituents that are considered to be hazardous waste. As such, the indiscriminate dumping or spillage of these fluids onto the ground may constitute a misdemeanor, punishable by fines and/or imprisonment, and shall not be allowed. The contractor is responsible for all hazardous waste relating to his work. The Geotechnical Consultant does not have expertise in this area. If hazardous waste is a concern, then the Client should acquire the services of a qualified environmental assessor.

2.2 Processing
Existing ground that has been declared satisfactory for support of fill by the Geotechnical Consultant shall be scarified to a minimum depth of 6 inches. Existing ground that is not satisfactory shall be over-excavated as specified in the following section. Scarification shall continue until soils are broken down and free of oversize material and the working surface is reasonably uniform, flat, and free of uneven features that would inhibit uniform compaction.

General Earthwork and Grading Specifications for Rough Grading Page 2

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2.3 Over-excavation
In addition to removals and over-excavations recommended in the approved geotechnical report(s) and the grading plan, soft, loose, dry, saturated, spongy, organic-rich, highly fractured or otherwise unsuitable ground shall be over-excavated to competent ground as evaluated by the Geotechnical Consultant during grading.

2.4 Benching
Where fills are to be placed on ground with slopes steeper than 5:1 (horizontal to vertical units), the ground shall be stepped or benched. Please see the Standard Details for a graphic illustration. The lowest bench or key shall be a minimum of 15 feet wide and at least 2 feet deep, into competent material as evaluated by the Geotechnical Consultant. Other benches shall be excavated a minimum height of 4 feet into competent material or as otherwise recommended by the Geotechnical Consultant. Fill placed on ground sloping flatter than 5:1 shall also be benched or otherwise over-excavated to provide a flat subgrade for the fill.

2.5 Evaluation/Acceptance of Fill Areas
All areas to receive fill, including removal and processed areas, key bottoms, and benches, shall be observed, mapped, elevations recorded, and/or tested prior to being accepted by the Geotechnical Consultant as suitable to receive fill. The Contractor shall obtain a written acceptance from the Geotechnical Consultant prior to fill placement. A licensed surveyor shall provide the survey control for determining elevations of processed areas, keys, and benches.

3.0 Fill Material

3.1 General
Material to be used as fill shall be essentially free of organic matter and other deleterious substances evaluated and accepted by the Geotechnical Consultant prior to placement. Soils of poor quality, such as those with unacceptable gradation, high expansion potential, or low strength shall be placed in areas acceptable to the Geotechnical Consultant or mixed with other soils to achieve satisfactory fill material.

3.2 Oversize
Oversize material defined as rock, or other irreducible material with a maximum dimension greater than 8 inches, shall not be buried or placed in fill unless location, materials, and placement methods are specifically accepted by the Geotechnical Consultant. Placement operations shall be such that nesting of oversized material does not occur and such that oversize material is completely surrounded by compacted or densified fill. Oversize material shall not be placed within 10 vertical feet of finish grade or within 2 feet of future utilities or underground construction.

General Earthwork and Grading Specifications for Rough Grading Page 3

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3.3 Import
If importing of fill material is required for grading, proposed import material shall meet the requirements of the geotechnical consultant. The potential import source shall be given to the Geotechnical Consultant at least 48 hours (2 working days) before importing begins so that its suitability can be determined and appropriate tests performed.

4.0 Fill Placement and Compaction

4.1 Fill Layers
Approved fill material shall be placed in areas prepared to receive fill (per Section 3.0) in near-horizontal layers not exceeding 8 inches in loose thickness. The Geotechnical Consultant may accept thicker layers if testing indicates the grading procedures can adequately compact the thicker layers. Each layer shall be spread evenly and mixed thoroughly to attain relative uniformity of material and moisture throughout.

4.2 Fill Moisture Conditioning
Fill soils shall be watered, dried back, blended, and/or mixed, as necessary to attain a relatively uniform moisture content at or slightly over optimum. Maximum density and optimum soil moisture content tests shall be performed in accordance with the American Society of Testing and Materials (ASTM Test Method D1557).

4.3 Compaction of Fill
After each layer has been moisture-conditioned, mixed, and evenly spread, it shall be uniformly compacted to not less than 90 percent of maximum dry density (ASTM Test Method D1557). Compaction equipment shall be adequately sized and be either specifically designed for soil compaction or of proven reliability to efficiently achieve the specified level of compaction with uniformity.

4.4 Compaction of Fill Slopes
In addition to normal compaction procedures specified above, compaction of slopes shall be accomplished by backrolling of slopes with sheepsfoot rollers at increments of 3 to 4 feet in fill elevation, or by other methods producing satisfactory results acceptable to the Geotechnical Consultant. Upon completion of grading, relative compaction of the fill, out to the slope face, shall be at least 90 percent of maximum density per ASTM Test Method D1557.

4.5 Compaction Testing
Field tests for moisture content and relative compaction of the fill soils shall be performed by the Geotechnical Consultant. Location and frequency of tests shall be at the Consultant's discretion based on field conditions encountered. Compaction test locations will not necessarily be selected on a random basis. Test locations shall be selected to verify adequacy of compaction levels in areas that are judged to be prone to inadequate compaction (such as close to slope faces and at the fill/bedrock benches).

General Earthwork and Grading Specifications for Rough Grading Page 4

Page 1765 of 2604 ends

4.6 Frequency of Compaction Testing
Tests shall be taken at intervals not exceeding 2 feet in vertical rise and/or 1,000 cubic yards of compacted fill soils embankment. In addition, as a guideline, at least one test shall be taken on slope faces for each 5,000 square feet of slope face and/or each 10 feet of vertical height of slope. The Contractor shall assure that fill construction is such that the testing schedule can be accomplished by the Geotechnical Consultant. The Contractor shall stop or slow down the earthwork construction if these minimum standards are not met.

4.7 Compaction Test Locations
The Geotechnical Consultant shall document the approximate elevation and horizontal coordinates of each test location. The Contractor shall coordinate with the project surveyor to assure that sufficient grade stakes are established so that the Geotechnical Consultant can determine the test locations with sufficient accuracy. At a minimum, two grade stakes within a horizontal distance of 100 feet and vertically less than 5 feet apart from potential test locations shall be provided.

5.0 Subdrain Installation
Subdrain systems shall be installed in accordance with the approved geotechnical report(s), the grading plan, and the Standard Details. The Geotechnical Consultant may recommend additional subdrains and/or changes in subdrain extent, location, grade, or material depending on conditions encountered during grading. All subdrains shall be surveyed by a land surveyor/civil engineer for line and grade after installation and prior to burial. Sufficient time should be allowed by the Contractor for these surveys.

6.0 Excavation
Excavations, as well as over-excavation for remedial purposes, shall be evaluated by the Geotechnical Consultant during grading. Remedial removal depths shown on geotechnical plans are estimates only.

The actual extent of removal shall be determined by the Geotechnical Consultant based on the field evaluation of exposed conditions during grading. Where fill-over-cut slopes are to be graded, the cut portion of the slope shall be made, evaluated, and accepted by the Geotechnical Consultant prior to placement of materials for construction of the fill portion of the slope, unless otherwise recommended by the Geotechnical Consultant.

7.0 Trench Backfills

7.1 The Contractor shall follow all OHSA and Cal/OSHA requirements for safety of trench excavations.

7.2 All bedding and backfill of utility trenches shall be done in accordance with the applicable provisions of Standard Specifications of Public Works Construction. Bedding material shall have a Sand Equivalent greater than 30 (SE>30). The bedding shall be placed to 1 foot over General Earthwork and Grading Specifications for Rough Grading Page 5

Page 1766 of 2604 ends

General Earthwork and Grading Specifications for Rough Grading Page 6 the top of the conduit and densified by jetting. Backfill shall be placed and densified to a minimum of 90 percent of maximum from 1 foot above the top of the conduit to the surface.

7.3 The jetting of the bedding around the conduits shall be observed by the Geotechnical Consultant.

7.4 The Geotechnical Consultant shall test the trench backfill for relative compaction. At least one test should be made for every 300 feet of trench and 2 feet of fill.

7.5 Lift thickness of trench backfill shall not exceed those allowed in the Standard Specifications of Public Works Construction unless the Contractor can demonstrate to the Geotechnical Consultant that the fill lift can be compacted to the minimum relative compaction by his alternative equipment and method.

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Appendix F
Confidential Paleontological Survey

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13 February 2024
Samuel Allen
Dudek
605 3rd Street
Encinitas, CA 92024
RE: Paleontological Records Search – Jericho Road Project Dear Mr. Allen:

This letter presents the results of a paleontological records search conducted for the Jericho Road Project (Project), located in the City of La Mesa, San Diego County, California. The Project site is located at 9407 Jericho Road and is bordered to the northeast by Jericho Road and existing residential development and to the northwest, southeast, and southwest by existing residential development.

Methods
A review of published geological maps covering the Project area and surrounding area was conducted to determine the specific geologic units underlying the Project area. Each geologic unit was subsequently assigned a paleontological resource sensitivity (Deméré and Walsh, 1993). In addition, a search of the paleontological collection records housed at the San Diego Natural History Museum (SDNHM) was conducted in order to determine if any documented fossil collection localities occur at the Project area or within the immediate surrounding area.

Results
Published geological reports (e.g., Todd, 2004) covering the Project area indicate that the proposed Project has the potential to impact the middle to late Eocene-age Pomerado Conglomerate and the middle Eocene-age Mission Valley Formation. These geologic units and their paleontological sensitivity are summarized below.

The SDNHM has two documented fossil collection localities within a one-mile radius of the Project site. The recorded fossil collection localities are from the Mission Valley Formation, and are discussed in more detail below. A map of the fossil localities is included as Figure 1, and a list of localities is provided in Appendix A.

Pomerado Conglomerate – The fluvial and nearshore marine deposits of the middle to late Eocene-age (approximately 37 to 42 million years old) Pomerado Conglomerate underlie the northeastern portion of the Project site. The SDNHM does not have any recorded fossil collection localities from the Pomerado Conglomerate within a one-mile radius of the Project. The lower conglomerate member of the Pomerado Conglomerate has yielded remains of terrestrial mammals (e.g., insectivores, primates, rodents, and artiodactyls), while the upper conglomerate member has yielded a particularly important and diverse assemblage of terrestrial mammals (e.g., Hypertragulus, Hyaenodon, Mesohippus, opossums, insectivores, and rodents). The middle Miramar Sandstone Member, meanwhile, has produced remains of nearshore marine mollusks (e.g., clams and snails) and a few

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Jericho Road Project - Paleontological Records Search 2 terrestrial mammals (e.g., Protoreodon, Leptoreodon, and Miacis) (Deméré and Walsh, 1993). The Pomerado Conglomerate is, therefore, assigned a high paleontological sensitivity.

Mission Valley Formation – The marine and fluvial deposits of the middle Eocene-age (approximately 43 million years old) Mission Valley Formation underlie the majority of the Project site.

The SDNHM has two recorded fossil collection localities from the Mission Valley Formation within a onemile radius of the Project area. These localities produced fossil remains of terrestrial vertebrates in the form of a partial cranium, dentary, limb elements, and teeth of the primitive oreodont Protoreodon walshi, and fossil teeth of the diminutive camelid Protylopus stocki. The marine strata of the Mission Valley Formation have produced abundant and well-preserved remains of marine microfossils (e.g., foraminifers), macroinvertebrates (e.g., clams, snails, crustaceans, and sea urchins), and vertebrates (e.g., sharks, rays, and bony fish) (Deméré and Walsh, 1993). The fluvial strata have produced wellpreserved petrified wood and assemblages of fossil land mammals (e.g., opossums, insectivores, bats, primates, rodents, artiodactyls, and perissodactyls) (Deméré and Walsh, 1993). The Mission Valley Formation is, therefore, assigned a high paleontological sensitivity.

Summary and Recommendations
The high paleontological sensitivity of the Pomerado Conglomerate and the Mission Valley Formation in the County of San Diego (Deméré and Walsh, 1993), as well as the presence of documented fossil collection localities from these geologic units in the vicinity of the Project site, suggests the potential for construction of the proposed Project to result in impacts to paleontological resources. Any proposed excavation activities that extend deep enough to encounter previously undisturbed deposits of these geologic units (i.e., below the depth of any previously imported artificial fill or disturbed sediments present within the Project area) have the potential to impact the paleontological resources preserved therein. If such excavation is required for Project construction, implementation of a complete paleontological resource mitigation program during ground-disturbing activities is recommended. The mitigation program must include, at a minimum, measures for construction monitoring, fossil salvage and data recovery, laboratory preparation and curation of the fossils into the permanent fossil collections of an appropriate regional repository, and production of a final paleontological mitigation report.

The fossil collection locality information contained within this paleontological records search should be considered private and is the sole property of the San Diego Natural History Museum. Any use or reprocessing of information contained within this document beyond the scope of the Jericho Road Project is prohibited.

If you have any questions concerning these findings please feel free to contact me at [email protected].

Sincerely,
Kirstin Mueller
Assistant Report Writer
San Diego Natural History Museum

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Jericho Road Project - Paleontological Records Search 3 Enc: Figure 1: Records search map
Appendix A: List of SDSNH fossil localities in the vicinity of the Project area Literature Cited
Deméré, T.A., and Walsh, S.L. 1993. Paleontological Resources, County of San Diego. Prepared for the San Diego Planning Commission: 1–68.

SDNHM unpublished paleontological collections data.

Todd, V.R. 2004. Preliminary Geologic Map of the El Cajon 30' x 60' Quadrangle, Southern California. U.S.

Geological Survey, Open-File Report 2004-1361.

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Jericho Road Project - Paleontological Records Search 4 Page 1791 of 2604 Appendix A: Locality List
San Diego Natural History Museum
Department of Paleontology
1 of 1
Locality Number Locality Name Location Elevation (feet) Geologic Unit Era Period Epoch 3539 Briarcrest Park City of La Mesa, San Diego County, California 657 Mission Valley Formation Cenozoic Paleogene middle Eocene 3638 Witherspoon Way City of El Cajon, San Diego County, California 700 Mission Valley Formation Cenozoic Paleogene middle Eocene

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Appendix G
Drainage Report

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R:\1790\Hyd\TM\DR\Reports\1790-DR.doc
w.o. 3087-12

DRAINAGE STUDY
for
Jericho Road
APN: 486-670-18-00
City of La Mesa, California
Prepared for:

Meritage Home
5 Peters Canyon Road, Suite 310
Irvine, CA, 92606
(949) 299-3847
W.O. 3087-12
July 28, 2023
Alisa S. Vialpando, R.C.E.

President
Hunsaker & Associates San Diego, Inc.

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Drainage Study
Jericho Road
R:\1790\Hyd\TM\DR\Reports\1790-DR.doc
w.o. 3087-12

TABLE OF CONTENTS

SECTION
Chapter 1 - Executive Summary I

1.1 Introduction &Vicinity Maps

1.2 Existing Condition

1.3 Proposed Condition

1.4 Conclusion

1.5 References
Chapter 2 - Methodology & Model Development II

2.1 Rational Method Hydrologic Analysis

2.2 Detention Analysis

2.3 County of San Diego Design Criteria
Chapter 3 - Rational Method Hydrologic Analysis III
(AES Model Output)

3.1 Existing Condition AES Model Output

3.2 Developed Condition AES Model Output
Chapter 4 – Detention Analysis IV

4.1 SWMM Model
Chapter 5 – Hydrology Exhibits
V

5.1 Existing Condition Hydrology Exhibit

5.2 Developed Condition Hydrology Exhibit
Chapter 6 – References
VI

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Drainage Study
Jericho Road
R:\1790\Hyd\TM\DR\Reports\1790-DR.doc
w.o. 3087-12

EXECUTIVE SUMMARY

1.1 Introduction
The Jericho Road project is situated at 9407 Jericho Road, on the southwest corner of the intersection of Amaya Drive and Broadmoor Drive, in the City of La Mesa, California. The 3.49-acre site, which is rectangular in shape, is bordered to the south by an existing multi-family residential community, and to the east, north, and west by existing single-family residential properties. A vicinity map is included below to better illustrate the project site’s location.

The redevelopment plan involves the removal of the current structures and proposes the construction of multi-family residences with 73 attached units with associated improvements. The site will also include a tot lot, open spaces, sidewalks, and private driveways. The lots are connected by private drives which are accessible via Jericho Rd on the east boundary.

This report aims to evaluate the existing and projected hydrological conditions in relation to the site's development. The proposed stormwater management infrastructure encompasses storm drain, curb inlets, catch basins, curb outlets, brow ditches, and an underground storage facility designed for water quality control, hydromodification, and detention (detention system made from corrugated metal

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Drainage Study
Jericho Road
R:\1790\Hyd\TM\DR\Reports\1790-DR.doc
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pipe (CMP) or equivalent). The storage facility will utilize a proprietary biofiltration modular wetland system downstream of it to provide water quality treatment.

This drainage study will address:
 100-Year Peak Flowrates for Existing and Developed Conditions  Detention Calculations
A separate report has been prepared to address water quality and HMP flow control requirements for the project. Refer to the Stormwater Quality Management Plan (SWQMP) for Jericho Road prepared by Hunsaker & Associates San Diego, Inc. (July 2023).

1.2 Existing Conditions
Under existing conditions, the Jericho Road site primarily serves as a church, comprising several buildings, a concrete parking area, an asphalt basketball court, and numerous open grassy spaces. Surface water flow from the northwestern portions of the site tends to move south towards an 18" x 18" catch basin situated within a sediment basin. This flow is subsequently directed eastward via an existing 3" HDPE drain, where it converges with runoff from the northeastern section before discharging onto Jericho Road through existing curb outlets.

Surface water from the southern part of the site flows south towards a 12" x 12" catch basin and then to an existing curb outlet (D25) on Jericho Road. This runoff then merges with additional runoff from the southeastern part of the site and is funneled south through the Jericho Road and Amaya Drive curb and gutter systems.

After approximately 815 feet, this runoff is intercepted by an inlet situated across from Water Street on Amaya Drive. The captured flow enters an existing 39” R.C.P. under Amaya Drive and continues southeast under Water Street, is then discharged via an existing 3.2’ X 5’ box culvert into an existing channel north of Janfred Road.

This runoff persists in its westward direction, entering a 10' X 5' R.C.B located southwest of the intersection of Amaya Drive and Severin Drive, then to dual 72” pipe which outlets into an existing open channel. This channel continues westerly to Alvarado Creek, eventually flowing into the lower San Diego River. The river subsequently empties into the Pacific Ocean at the mouth of the San Diego River.

The runoff coefficient corresponding to the site was calculated considering the respective hydrologic soil type and imperviousness, following the guidelines set forth in Table 3-1 of the San Diego County Hydrology Manual 2003. The computed runoff coefficient for the on-site drainage area associated with 48% imperviousness and Soil type D is approximately 0.618, while the slope contributes a runoff factor of

0.35. Table 1 below summarizes the 100-year existing condition peak flow at the downstream project boundary. Supporting calculations for the data presented in

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La Mesa City CouncilMay 13, 2025

La Mesa City Council
May 13, 2025