around the residential area. We conclude that R&D office Buildings 1 and 3 and the parking structure may be supported on shallow foundations on a minimum of 24 inches of engineered fill. We conclude that with the excavation planned for one level of below grade parking for R&D office Building 1, it can also be supported on shallow spread-type footings that bear on a layer of well-compacted fill. To mitigate excessive settlement from a seismic event at Building 2, additional measures such as ground improvement or over-excavation are needed. We conclude that the proposed residential development may be supported on shallow foundations on a minimum of 10 feet of engineered fill or competent native soil. Our recommendations regarding foundations, site grading, fill compaction, and other geotechnical aspects of this project are presented in this geotechnical investigation report.
We appreciate the opportunity to provide our services to you on this project. If you have any questions, please call.
Sincerely yours,
HALEY & ALDRICH, INC.
Liang Chow, PE (MN)
Project Manager
Catherine H. Ellis, PE, GE (CA)
Senior Associate, Geotechnical Engineer
Enclosures
\\haleyaldrich\share\CF\Projects\0204226\000\Geo\Deliverables\Reports\2022-0511_HAI_180 El Camino_Geotech_F_REV1.docx Table of Contents
Page
i
List of Tables iii
List of Figures iii
List of Appendices iv
1. Introduction 1
1.1 PURPOSE AND SCOPE 1
2. Site Conditions and Proposed Construction 3
2.1 SITE HISTORY 3
2.2 PROPOSED CONSTRUCTION 3
3. Geology 5
3.1 REGIONAL GEOLOGY 5
3.2 REGIONAL SEISMICITY 5
4. Subsurface Explorations 7
4.1 BORINGS 7
4.2 CONE PENETRATION TESTS 8
4.3 PERCOLATION TEST 8
4.4 FIELD EXPLORATION BY OTHERS 9
4.5 GEOTECHNICAL LABORATORY TESTING 9
4.6 GEOTECHNICAL LABORATORY TESTING BY OTHERS 9
5. Subsurface Soil and Groundwater Conditions 10
5.1 SUBSURFACE CONDITIONS 10
5.2 SHEAR WAVE VELOCITY CONDITIONS 10
5.3 GROUNDWATER CONDITIONS 10
6. Discussion and Conclusions 12
6.1 SEISMICITY AND SEISMIC HAZARDS 12
6.1.1 Site Seismicity 12
6.1.2 Soil Liquefaction 13
6.1.1 Lateral Spreading 15
6.1.1 Sand Boils 15
6.1.2 Cyclic Densification 15
6.1.3 Fault Rupture 16
6.1.1 Tsunami 16
6.2 EXPANSION POTENTIAL 16
Table of Contents
Page
ii
6.3 FOUNDATIONS AND SETTLEMENT 16
7. Recommendations 18
7.1 EARTHWORKS 18
7.1.1 Site Preparation and Grading 18
7.1.2 Subgrade Preparation 18
7.1.3 Material for Fill 19
7.1.4 Re-Use of On-site Material 19
7.1.5 Fill Placement and Compaction 20
7.1.6 Weak or Wet Subgrade Mitigation 21
7.1.7 Underground Utilities 21
7.2 FOUNDATIONS 22
7.2.1 Shallow Foundations without Ground Improvement 22
7.2.2 Shallow Foundations over Ground Improvement 23
7.2.3 Ground Improvement 24
7.3 SLABS-ON-GRADE 25
7.3.1 Floor Slabs 25
7.3.2 Exterior Flatwork 26
7.4 STORMWATER INFILTRATION 26
7.5 SURFACE DRAINAGE 27
7.6 FLEXIBLE PAVEMENT DESIGN 27
7.7 RIGID PAVEMENT DESIGN 28
7.8 TEMPORARY EXCAVATION SHORING 29
7.8.1 General Considerations 29
7.8.2 Lateral Earth Pressures 30
7.8.3 Shoring Installation 31
7.8.4 Design and Construction of Tiebacks 31
7.9 RETAINING WALLS 32
7.10 TEMPORARY DEWATERING 33
7.11 CORROSION POTENTIAL 33
8. Supplemental Geotechnical Services 34
9. Limitations 35
References 36
iii
List of Tables
Table No. Title
I Active Faults within 50 km of the Site (embedded, p. 5) II WGCEP (2015) Estimates of 30-Year Probability of a Magnitude 6.7 or Greater Earthquake (embedded, p. 6)
III Seismic Design Parameters (embedded, p. 13)
IV Liquefaction Screening Values (embedded, p. 14)
V Values Used in Liquefaction Evaluation (embedded, p. 14) VI Estimated Liquefaction Settlement (embedded, p. 15)
VII General Engineered Fill Grading Requirements (embedded, p. 19) VIII Class 2 Aggregate Base Grading Requirements (embedded, p. 20) IX Summary of Compaction Recommendations (embedded, p. 20) X Gradation Requirements for Capillary Moisture Break (embedded, p. 26) XI Flexible Pavement Design (R-Value = 20) (embedded, p. 28) XII Rigid Pavement Design (embedded, p. 29)
XIII Corrosivity Analysis Results (embedded, p. 33)
List of Figures
Figure No. Title
1 Project Locus
2 Site Plan
3 Regional Geologic Map
4 Site Plan and Site Geology
5 Temporary Lateral Earth Pressures for Excavation
iv
List of Appendices
Appendix Title
A Boring Logs
B Cone Penetration Test Results
C Infiltration Test Results
D Previous Boring Logs and Cone Penetration Test Results E Laboratory Testing Results
F Previous Testing Results
1 1. Introduction
This report presents the results of Haley & Aldrich, Inc.’s (Haley & Aldrich’s) geotechnical investigation of the proposed Research and Development (R&D) office buildings, residential buildings, and parking structure project in South San Francisco, California. The approximately 9.3-acre project site is located at the east corner of the intersection of El Camino Real and South Spruce Avenue (Site), as shown on Figure
1. The proposed R&D office buildings and parking structure are located in the southern half and the residential and retail buildings are located in the northern portion of the Site. This report describes the subsurface explorations performed at the Site, provides our interpretation of the subsurface data, and includes geotechnical recommendations for the proposed R&D, residential buildings, and parking structure development. The peer-review of the retail buildings was discussed in a separate report, entitled “Third-Party Peer Review of Geotechnical Engineering Studies,” dated 25 February 2022 prepared by Haley & Aldrich.
The project team includes Skidmore, Owings & Merrill, LLP (Architect); International Parking Design, Inc. (Structural Engineer for the parking structure); KPW Structural Engineers, Inc., a Salas O'Brien Company (Structural Engineers for the residential and R&D buildings); and Ware Malcomb (Civil Engineer).
1.1 PURPOSE AND SCOPE
This geotechnical investigation was performed to obtain geotechnical information on subsurface conditions at the Site and develop geotechnical design recommendations for the subject project. The scope of the investigation as outlined in our proposal dated 7 January 2022 and authorized on 2 February 2022 included the following:
Preparing a site-specific health and safety plan;
Visiting the Site to mark out the geotechnical investigation locations and coordinate utilities clearance;
Notifying DigAlert at least 48 hours in advance of fieldwork; A geotechnical field investigation consisting of:
– three (3) soil borings drilled to a depth of about 10 feet below ground surface (bgs); – one (1) seismic cone penetration test (CPT) advanced to 100 feet bgs with shear wave velocity measurements; and
– three (3) field infiltration tests;
Reviewing readily available geotechnical and geologic reports pertaining to the Site, specifically the previous report prepared by Geosphere Consultants, Inc (GCI, March 2016), Rockridge Geotechnical (Rockridge, December 2020), and Geo-Engineering Solutions, Inc. (GES, November 2021);
Engineering analyses based on the results of the proposed field and laboratory testing investigation performed by Haley & Aldrich, also based on a review of the previous field and laboratory testing investigation presented in the GCI (2016) and GES (2021) reports; Preparing a geotechnical report presenting our conclusions and recommendations for the R&D office buildings, residential buildings, and parking structure regarding:
2 – Soil and groundwater conditions at the Site;
– Expansion potential of the on-site soils based on geotechnical laboratory tests and proper mitigation methods (if required);
– Site seismicity and seismic hazards including potential from seismic events; – Analyses of the infiltration rate based on the proposed infiltration tests; – Foundation design criteria for the proposed buildings, including foundation type(s), design capacities for various foundation systems capable of supporting the planned structure, and Site improvements;
– Amount of settlement anticipated, given the presence of the new and existing fill materials, proposed building foundations and slab-on-grades, and new Site improvements;
– Uplift evaluation of the substructures and recommendations (if any); – Design criteria for vertical and lateral support of the structures (if required); – Design lateral earth pressures and drainage requirements for ramp retaining walls; – Temporary shoring design parameters and an evaluation of the open cut stability for the utility trench constructions;
– Recommendations for slabs-on-grade, including floor slabs and exterior concrete flatwork;
– Recommendations regarding the proposed earthwork, including excavation, backfill, subgrade preparation, utility trench, non-expansive import fill (if required), slab-ongrade subgrade, retaining wall backfill, import fill material; – Flexible asphalt-concrete and rigid Portland cement concrete pavement designs; – Corrosion potential of the on-Site soils; and
– Construction considerations (as appropriate).
3 2. Site Conditions and Proposed Construction
The Site lies at the east corner of the intersection of El Camino Real and South Spruce Avenue as presented on Figure 1 and the proposed building locations are presented on Figure 2. The Site coordinates are approximately 37.643040 degrees north and 122.422499 degrees west. The Site slopes down toward the north with site grades ranging between approximately Elevation (El.) 28 and 52 feet National Geodetic Vertical Datum of 1929. The high elevation of 52 feet is located at the southwest corner of the site.
Nearby site features include residential, commercial, and office facilities. One- to 2-story family dwellings, restaurants, gas stations, and retail stores are located on the west and south sides of the Site.
A chocolate shop and parking lot occupy the property across South Spruce Avenue on the north. A worship and service center and a multi-use office building occupies the northeast corner of the Site.
Other commercial facilities and office buildings occupy Huntington Avenue on the east side.
2.1 SITE HISTORY
Historical aerial photographs indicate that the Site has been occupied by the existing building and parking lot since the 1980s or earlier. A service station was located in the west corner of the Site, next to the intersection of El Camino Real and South Spruce Avenue. However, the service station was demolished in April 2016.
2.2 PROPOSED CONSTRUCTION
Based on the provided plans, entitled “Planning Application Resubmittal” prepared by Skidmore, Owings & Merrill, LLP, dated 1 March 2022, we understand the proposed project will include three (3) new R&D office buildings and a parking structure in the southern half of the Site, and retail and residential buildings in the northern half of the Site. The proposed office buildings will be 6 stories high with a total footprint of 750,164 square feet (sq ft) and the parking structure will be a 7-story building with a total footprint of approximately 67,000 sq ft. One of the R&D buildings, Building 1 in the southwest of the Site, will include a one-level basement for parking. Buildings 2 and 3 are to the east of Building 1. The parking structure is planned for the eastern portion of the Site. Three (3) retail buildings with a total of 30,000 sq ft and residential buildings are also planned at the northern half of the Site. The retail buildings will be served by a surface parking lot adjacent to them and which will provide parking at a ratio of 4 spaces per 1,000 sq ft of new retail area. The proposed residential building will be a 7-story building with plazas, amenities, and gardens. The project will also include underground utilities, asphalt and concrete pavements, stormwater management facilities, and landscaping.
We understand that the project design drawings have not been prepared. We have assumed that structural loads will be on the order of 100 to 200 kips of dead plus live load for the R&D and residential buildings. The structural loads for the parking structure will be 750 kips to 1,650 kips of dead plus live loads for the exterior and interior of the structure. General fills for Buildings 2 and 3 are anticipated to be on the order of between 4 and 6 feet. Grade raise at the residential portion will be highest in the north corner, where existing grade is lowest across the Site. Fills of up to about 2.5 feet and cuts of up to about 8 feet are anticipated. To generate the access around and for the basement for Building 1, a retaining wall is planned along El Camino Real where the road slopes down toward north. The retaining wall will be two-tier with each tier about 7 feet tall. Temporary shoring for the retaining wall is 4 anticipated to be on the order of 11 to 23½ feet, varying with the grades near El Camino Real. The bottom of the excavation is anticipated to be at about elevation 28.5 feet to create the finished grade for the building pad. Ramps for the parking structure from the ground, or first level, up to the second level are assumed to be on the order of 10 feet or less. Infiltration basins for stormwater management are assumed to be on the order of 5 feet or less.
If the project differs significantly from that described, we should be contacted to review the applicability of our recommendations.
5 3. Geology
3.1 REGIONAL GEOLOGY
The Site is located on the San Francisco Peninsula at the western Shoreline of the San Francisco Bay in the Coast Ranges Geomorphic Province. The Coast Ranges Province is defined by northwest-trending mountain ridges and valleys that run approximately parallel to the San Andreas Fault Zone. The bedrock within the province generally consists of Tertiary marine sedimentary deposits and volcanic rocks. The upper bedrock is at least 200 feet bgs. The Site and surrounding area are inland of the former Bay margin shoreline and to the east of the Santa Cruz Mountain Range, except for San Bruno Mountain, which is located to the north of the Site. Based on mapping by Brabb and Pampeyan (1983), the Site is underlain by Quaternary surficial deposits of the Colma formation on the southern half of the Site and younger alluvial fan deposits on the northern half of the Site, as shown in Figure 3. The “Qoa” unit described as the Colma Formation consists of yellowish-gray to gray to yellowish-orange and red-brown, friable to loose, fine- to medium-grained sand with subordinate amounts of gravel, silt, and clay. The “Qha” unit described as younger alluvial fan deposits consists of unconsolidated fine- to coarse-grained sand, silt, and gravel deposited from the ancient stream channel in the northwestern edge of the Site.
3.2 REGIONAL SEISMICITY
The major active faults closest to the Site are the San Andreas, and San Gregorio, and Hayward-Rodgers Creek faults. For each of the active faults within 50 kilometers (km) of the Site, the distance and direction from the Site and estimated maximum Moment magnitude,1 Mw, are presented in Table I.
TABLE I
Active Faults within 50 km of the Site
Fault Name
USGS
Fault
No.1
Distance
(km)1
Direction
from Site1
Mean
Characteristic Moment
Magnitude
Mean Slip
Rate1
(mm/yr)
Fault
Length1
(km)
San Andreas 1 3 West 7.95 9 410
San Gregorio Connected 60 12 West 7.50 >5.0 176
Hayward-Rodgers Creek 55 27 East 7.33 9 150
Monte Vista-Shannon 56 27 Southeast 6.50 0.2-1.0 45
Calaveras 54 41 East 7.03 >5.0 123
Mount Diablo Thrust 353 42 Northeast 6.70 1.0-5.0 25
Green Valley Connected 37 49 Northeast 6.80 1.0-5.0 56
Point Reyes 61 50 Northwest 6.90 0.3 47
Notes:
1) Source: USGS Quaternary Fault and Fold Database of the United States.
Since 1800, four major earthquakes have been recorded on the San Andreas Fault, as summarized below:
1836: An earthquake with an estimated maximum intensity of VII on the Modified Mercalli (MM) scale occurred east of Monterey Bay, reportedly on the San Andreas Fault (Toppozada and 1 Moment magnitude is an energy-based scale used to provide a physically meaningful measure of the size of a faulting event. Moment magnitude is directly related to average slip and fault rupture area. 6 Borchardt, 1998). The estimated Moment magnitude, Mw, for this earthquake is about 6.25. This earthquake was previously thought to have occurred on the northern portion of the Hayward Fault.
1838: An earthquake occurred on the San Andreas Fault with an estimated intensity of about VIII-IX (MM), corresponding to an Mw of about 7.5.
1906: The San Francisco Earthquake of 1906 caused the most significant damage in the history of the Bay Area in terms of loss of lives and property damage. This earthquake created a surface rupture approximately 470 km in length along the San Andreas Fault from Shelter Cove to San Juan Bautista. It had a maximum intensity of XI (MM), an Mw of about 7.9, and was felt 560 km away in Oregon, Nevada, and Los Angeles.
1989: The most recent major earthquake to affect the Bay Area was the Loma Prieta Earthquake of 17 October 1989. It occurred in the Santa Cruz Mountains with an Mw of 6.9 and was approximately 33 km from the Site.
Several earthquakes have also been recorded on the Hayward and Calaveras Faults since the late 1800s, as summarized below:
1861: An earthquake of unknown magnitude (probably an Mw of about 6.5) was reported on the Calaveras Fault.
1868: An earthquake with an estimated maximum intensity of X on the MM scale occurred on the southern segment (between San Leandro and Fremont) of the Hayward Fault. The estimated Mw for the earthquake is 7.0.
1984: The most recent significant earthquake on the Calaveras Fault was the 1984 Morgan Hill earthquake (Mw = 6.2).
The 2014 Working Group on California Earthquake Probabilities (WGCEP) at the U.S. Geological Survey (USGS), in coordination with the California Geological Survey (CGS) and Southern California Earthquake Center, predicted a 72 percent chance of a magnitude 6.7 or greater earthquake occurring in the San Francisco Bay Area in 30 years (i.e., before the year 2044). More specific estimates of the probabilities for different faults in the Bay Area are presented in Table II.
TABLE II
WGCEP (2015) Estimates of 30-Year Probability
of a Magnitude 6.7 or Greater Earthquake
Fault Name Probability (%)
Hayward-Rodgers Creek 14.0
San Andreas 6.4
San Gregorio Connected 2.6
Mount Diablo Thrust 2.6
7 4. Subsurface Explorations
This report is based on the field exploration program performed by Geosphere Consultants, Inc. in 2014, Geo-Engineering Solutions, Inc. in November 2021, and Haley & Aldrich on 14 February 2022. The approximate locations and designations of the subsurface explorations performed are shown on Figure
2. We increased the number of borings to six from three that had been initially proposed.
Haley & Aldrich explored the subsurface conditions at the Site by:
drilling six (6) exploratory borings (designated HA-1 through HA-6) to a maximum depth of about
17.5 feet bgs, using a truck-mounted hollow stem auger drill rig; advancing one (1) CPT (designated SCPT-1) and performing seismic shear wave velocity testing to a depth of 80 feet, when the CPT encountered refusal; performing two (2) shallow infiltration tests (designated as HA-1 and HA-2) to test the infiltration rate of the soils within the upper 2 to 5 feet of the Site; and completing a geotechnical laboratory testing program.
A summary of the various exploration programs is presented below.
4.1 BORINGS
On 14 February 2022, Haley & Aldrich explored the subsurface conditions at the Site by drilling exploratory borings HA-1 through HA-6 to depths ranging from about 7 to 17.5 feet bgs, using a truckmounted drill rig. Prior to performing our field investigation, we notified Underground Service Alert (USA) and retained a private utility locator to check that the boring locations were clear of existing utilities.
The borings were drilled by Pitcher Drilling Services of Palo Alto, California under the direction of our field engineer, who logged each hole and collected samples for soil classification and laboratory testing purposes. Soil samples were obtained at discrete locations during drilling using a Modified California sampler (MCS) and a Standard Penetration Test (SPT) sampler. The locations where each sample was collected are shown on the boring logs. The MCS has a 3.0-inch outside diameter and a 2.43-inch inside diameter and is lined with three, 6-inch-long brass or stainless steel tubes. The unlined SPT sampler has a 2.0-inch outside diameter and a 1.38-inch inside diameter. MCS and SPT soil samples were collected by driving each respective sampler to a depth of 18 inches or to penetration refusal, whichever was encountered first, using a 140-pound, above-ground automatic hammer falling approximately 30 inches.
Uncorrected blow counts were recorded for each 6-inch-long interval of sampler penetration and are presented on the boring logs in Appendix A. After the samplers were withdrawn from the test borings, the samples were removed, examined for logging purposes, labeled, and sealed to retain the natural moisture content for laboratory testing. Prior to sealing the samples, strength characteristics of the cohesive soil samples recovered were evaluated using a hand-held pocket penetrometer. The results of these tests are shown adjacent to the samples on the boring logs in Appendix A.
Upon completion of the drilling work, each boring was filled to the surface with a cement grout in accordance with the San Mateo County Environmental Health Services Division permit requirements. 8 Soil cuttings generated during the subsurface investigation were collected in 55-gallon drums with lids and were submitted to an environmental laboratory to analyze for off-site disposal purposes.
4.2 CONE PENETRATION TESTS
On 14 February 2022, a CPT with shear wave measurements (designated as SCPT-1) was performed by Middle Earth Geo Testing, Inc. (Middle Earth) of Hayward, California. The SCPT-1 was advanced to a depth of 80 feet, when the CPT encountered refusal. The CPT consisted of hydraulically pushing a
1.75-inch diameter, cone-tipped probe into the soil using a rig with a push capacity of 20 tons. The cone tip measures tip resistance and the friction sleeve behind the cone tip measures frictional resistance.
Electrical strain gauges within the cone continuously measured soil parameters during the entire depth the cone was advanced. Soil data, including tip resistance and frictional resistance, were recorded and then processed to provide information for use in our geotechnical engineering analyses. One pore pressure dissipation test was performed at a depth of 27.9 feet to measure hydrostatic water pressures and to infer the approximate depth to groundwater. Upon completion, the CPT hole was backfilled with cement grout in accordance with San Mateo County Environmental Health Services Division permit requirements.
To conduct the seismic shear wave test, the penetration of the cone is stopped and the rods are decoupled from the rig. An automatic hammer is triggered to send a shear wave into the soil. The distance from the source to the cone is calculated knowing the total depth of the cone and the horizontal offset distance between the source and the cone. Seismic shear wave tests were performed at every 5-foot interval to a depth of 80 feet at SCPT-1.
The stratigraphic interpretation of the CPT data was performed based on relationships between cone bearing and sleeve friction versus penetration depth. The friction ratio, which is sleeve friction divided by cone bearing, is a calculated parameter used to infer soil behavior type. Generally, cohesive soils (clays) have high friction ratios, low cone bearing and generate large excess pore water pressures.
Cohesionless soils (sands) have lower friction ratios, high cone bearing and generate small excess pore water pressures. The interpretation of soil properties from the cone data has been carried out using recent correlations developed by Robertson and Cabal (2010). The CPT log and shear wave velocity tests generated for the exploration program by Middle Earth, showing tip resistance and friction ratio by depth and interpreted soil classifications and strengths, are presented in Appendix B.
4.3 PERCOLATION TEST
Two boring percolation tests2 were performed at locations HA-1 and HA-2 on 14 February 2022. The percolation tests consisted of installing a 2-inch diameter slotted PVC pipe in the center of the borings to a depth of approximately 5 feet bgs. The area around the pipe was backfilled with filter sand to a depth of approximately 2 feet bgs. Hydrated bentonite was used to fill the area around the pipe at depths between 2 feet bgs and the ground surface. The borings were presoaked to the level of the ground surface prior to testing the infiltration rate of the hole. The change in depth for the water was measured at 30-minute intervals. After each reading, the water level was restored to the same approximate starting depth (i.e., level with the surrounding ground surface) for subsequent test runs. Testing at each location was halted once the rate of percolation stabilized, as determined by relatively consistent 2 The percolation tests were performed in general accordance with the guidelines presented in the County of Los Angeles Department of Public Works Administrative Manual GS200.1. 9 readings over three consecutive test intervals (defined as less than 10 percent change in the rate of percolation over three tests). The results of our testing are discussed in the “Stormwater Infiltration” section of this report and the percolation test data are presented in Appendix C.
We had originally planned for three field infiltration tests within the landscaping areas. However, due to actual Site conditions including deeper than anticipated fill thicknesses, one of the field tests was eliminated. The infiltration tests that we performed were located within the proposed R&D office buildings and parking structure.
4.4 FIELD EXPLORATION BY OTHERS
Geosphere Consultants, Inc. (GCI, 2016) and Geo-Engineering Solutions, Inc. (GES, 2021) completed field investigations in 2014 and 2021, respectively. Their investigations included:
Eight (8) exploratory borings (designated B-1 through B-8) were drilled to a maximum depth of about 40 feet bgs, using a truck-mounted hollow stem auger drill rig; GCI performed sixteen (16) CPTs (designated as CPT-1 through CPT-16) to a maximum depth of approximately 50 feet bgs;
GES performed an additional three (3) CPTs (designated as CPT-01A to CPT-03A) to a maximum depth of 62 feet bgs near the proposed retail development; and Completed a geotechnical laboratory testing program.
Previous borings and CPTs are presented in Appendix D.
4.5 GEOTECHNICAL LABORATORY TESTING
Soil samples from the exploratory test borings were re-examined at our office to review their Unified Soil Classification System (USCS) classification and selected samples were submitted to Inspection Services, Inc. (ISI) in Berkeley, California for geotechnical laboratory testing. Samples were tested for Atterberg limits and fines content (P200). Geotechnical laboratory test results are presented in Appendix E.
Additionally two samples of near-surface soil were submitted to CERCO Analytical, Inc. of Concord, California and tested for corrosion properties, including pH, resistivity, sulfate content, and chloride content. The results of the testing are included in Appendix E.
4.6 GEOTECHNICAL LABORATORY TESTING BY OTHERS
A geotechnical laboratory testing program was completed by GCI and GES to measure engineering properties, including strength and various indices. Soil properties were measured, including expansion indices, sieve analysis, and corrosivity. The results of the previous testing are presented in Appendix F. 10 5. Subsurface Soil and Groundwater Conditions
5.1 SUBSURFACE CONDITIONS
Based on our review of existing geotechnical reports and information gathered during our geotechnical investigation, we estimate that approximately 1 to 13 feet of undocumented fill is present below the asphalt concrete pavement. The fill thickness varied by area. In general, we encountered greater fill thickness in the northern portion of the Site than in the southern half. Based on the existing boring logs (GCI, 2016) and our borings, the fill thickness within the R&D buildings and parking structure is about 1 foot. Where encountered, the fill generally consists of stiff clay with sand. In the asphalt driveway and parking lot areas, the thickness of asphalt concrete ranged from 3 to 4 inches and is underlain by about 6 inches of aggregate base type material. Near the residential area, borings HA-4, HA-5 and HA-6 encountered fill to depths of 5 to 13 feet bgs. Boring HA-4 encountered refusal on concrete at a depth of 7 feet bgs. Below the fill, the borings that we drilled generally encountered alluvium (medium dense sand, silty sand, and sandy silt) to the maximum boring depth of 17½ feet bgs. The locations of our geotechnical investigation locations, along with previous investigation locations from others and geologic information are shown in Figure 4.
In the northern portion of the Site, the subsurface conditions generally consist of interbedded medium dense to dense silty sand or sandy silt and stiff to very stiff sandy lean clay and clayey soils to depths of about 20 to 25 feet bgs. Below that, CPT-1 through CPT-3 encountered a medium stiff clay layer to about 30 feet, which in turn is underlain by interbedded layers to the maximum exploration depths of about 45 feet. The southern half of the Site is mostly underlain by stiff to very stiff clay. However, borings B-4, B-6, and soundings CPT-13 and SCPT-1 encountered silty sand to sandy silt to a depth of approximately 20 feet bgs, with interbedded sandy lean clay or lean clay layers extending from about 20 to 40 feet bgs, and a lower dense sand layer at approximately 65 to 80 feet bgs.
5.2 SHEAR WAVE VELOCITY CONDITIONS
A shear wave velocity profile of subsurface alluvial soils at the Site was recorded by means of seismic CPT shear wave testing at SCPT-1. The test results indicate that the average shear wave velocity of the soils within the upper 80 feet of the Site is approximately 281 meters per second (m/s) (928 feet per second [ft/s]).
5.3 GROUNDWATER CONDITIONS
GCI (2016) reported groundwater at depths ranging from 31 to 38 feet within their borings and approximately 20 feet within their CPTs during their exploration in September 2014. GES (2021) encountered groundwater at a depth of 20 feet in the additional CPTs in late October 2021. During our subsurface explorations in mid-February 2022, we encountered groundwater at a depth of approximately 18 feet bgs in our SCPT. However, none of our borings encountered groundwater at the maximum exploration depth of about 17½ feet bgs.
Historical groundwater at the project site was mapped by CGS (2021) at depths ranging from 2 to 30 feet bgs. However, the mapped groundwater may not reflect site modifications such as placement of fill.
Significant fill was placed for the original development of the Site. Shallow groundwater levels are mostly located along the San Francisco Bay shorelines and adjoining flatlands. Reviews by GCI (2016) 11 and GES (2021) of the San Francisco South quadrangle map indicate a historical high groundwater at about 20 feet bgs. Rockridge also cites a groundwater monitoring report prepared by Stantec in November 2014, for a former service station located at 190-192 El Camino Real, which indicated a historical high groundwater elevation at 20 feet based on North American Vertical Datum (NAVD) of 1988. Based on our findings, we recommend that a design groundwater depth of 20 feet bgs be used.
However, the local groundwater levels can fluctuate depending on factors such as seasonal rainfall, groundwater withdrawal and construction activities on this or adjacent properties. The influence of these time dependent factors could not be determined at the time of our investigation. 12 6. Discussion and Conclusions
Based on our review of subsurface information for the Site, we conclude the primary geotechnical issues affecting the design and construction of the planned industrial development include the following:
very strong site seismicity and potential seismic hazards; presence of undocumented fill near the existing ground surface within the residential area; very low expansive soil conditions near the existing ground surface; and selection of an appropriate foundation system(s).
Our discussion of these and other geotechnical issues are presented in the remainder of this report.
6.1 SEISMICITY AND SEISMIC HAZARDS
During a major earthquake, seismic shaking has the potential to occur at the site, as is typical throughout the Bay Area, and as experienced during the 1989 Loma Prieta event. Shaking during an earthquake can result in ground failure, such as that associated with soil liquefaction, lateral spreading, and cyclic densification. Haley & Aldrich’s assessment of these potential seismic hazards are presented in the following sections.
6.1.1 Site Seismicity
A seismic hazard analysis was performed using the USGS Unified Hazard Tool (https://earthquake.usgs.gov/hazards/interactive/) website. Our deaggregation analysis utilized the USGS Dynamic Conterminous U.S. 2014 (v.4.2) edition. For our analyses, we evaluated the Site as Site Class D, based on an average shear wave velocity over the top 80 feet (24 meters) of the site (Vs30) of about 928 ft/s; this value was calculated based on the average shear wave velocity measured at SCPT-1 during our field investigation on 14 February 2022.
Based on the seismicity of faults that may impact the Site and the results of the deaggregation analysis, a design earthquake with an Mw of 7.86 was selected for the seismic hazard evaluation. The peak horizontal ground acceleration (PHGA) for the Site, which is based on the Maximum Considered Earthquake (MCE) with a return interval of 2,475 years, or a 2 percent probability of exceedance in 50 years, is 1.03g. The risk-based site-modified peak ground acceleration (PGAM) for the Site is also
1.03g; this value was computed based on procedures outlined in ASCE 7-16 (ASCE, 2017).
Recommended code-based seismic parameters for design of the proposed structures in conformance with the 2019 California Building Code (California Building Standards Commission, 2019) and ASCE 7-16 are presented in Table III.
13 TABLE III
Seismic Design Parameters
Seismic Parameter Design Value
Site Class (ASCE 7-16 Table 1613.5.2) D
Risk Category II
MCER
1 Ground Motion (Period = 0.2 seconds), Ss 2.187 g
MCER Ground Motion (Period = 1.0 seconds), S1 0.91 g
Peak Ground Acceleration, PGA 0.936 g
Site Amplification Factor at 0.2 seconds, Fa 1.0
Site Amplification Factor at 1.0 seconds, Fv --
Site Amplification Factor for PGA, FPGA 1.1
Site-Modified Peak Ground Acceleration, PGAM 1.03 g
Site-Modified Spectral Acceleration Value at 0.2 seconds, SMS 2.187 g Site-Modified Spectral Acceleration Value at 1.0 seconds, SM1 -- Design Spectral Acceleration at 0.2 seconds, SDS 1.458 g Design Spectral Acceleration at 1.0 seconds, SD1 --
Notes:
1) MCER = Risk-targeted maximum considered earthquake
2) g = acceleration of gravity
3) Values of Fv, SM1, and SD1 are undefined for this site class without performance of a site-specific ground motion hazard analysis. 4) Design values presented above are based on a site located at latitude / longitude = 37.64304 / -122.422499.
6.1.2 Soil Liquefaction
Liquefaction is the process in which saturated, cohesionless soil experiences a temporary loss of strength due to the buildup of excess pore water pressure during cyclic loading resulting from earthquake ground motions. The type of soils most susceptible to liquefaction are loose, clean, saturated, uniformly graded sand and silt that have low clay content. Flow failure, lateral spreading, differential settlement, loss of bearing strength, ground fissures, and sand boils are evidence of liquefaction.
According to an evaluation by CGS (2021) for seismically induced hazards, the project site is mapped within a Seismic Hazard Zone that may have the potential for liquefaction.
We performed screening for liquefiable soils using the Boulanger and Idriss (2014) criteria, which state that fine-grained soils with a plasticity index of 7 or greater are not susceptible to liquefaction. GCI (2016) reported Atterberg Limits testing results for a sample at boring B-7, the results of which are shown in Table IV. Haley & Aldrich performed one Atterberg Limits test on a sample obtained within boring HA-4. Plasticity indexes from each of these samples indicate that the selected clayey soils (CL) are not susceptible to liquefaction. However, the silty and clayey soils (CL-ML) and the silty sand (SM, SP-SM), if saturated or below groundwater, can be susceptible to liquefaction. 14 TABLE IV
Liquefaction Screening Values
Exploration
No.
Sample Depth
(ft)
Plasticity
Index (PI)
Liquid
Limit (LL)
USCS Soil
Type
LB-1* 2 9 26 CL
B-7* 2 4 22 CL-ML
HA-4 5-6.5 15 31 CL
Notes:
1) Asterisk (*) refers to data from the Geosphere Consultants, Inc. report (GCI, 2016).
We evaluated liquefaction potential at the Site by performing analyses in accordance with the methodology presented in publications prepared by T.L. Youd and others (Youd, 2001) for the National Center for Earthquake Engineering Research (NCEER).
The parameters used in the liquefaction evaluation are shown in Table V. We used a groundwater depth of 20 feet to evaluate CPT data from previous studies, except SCPT-1, where we used a groundwater depth of 18.2 feet as interpreted from our pore pressure dissipation test. In the previous studies, CPTs were terminated at a depth shallower than 50 feet. Because design groundwater depth is 20 feet, we only evaluate those CPTs having a maximum exploration depth of at least 30 feet bgs.
TABLE V
Values Used in Liquefaction Evaluation
Liquefaction Evaluation Parameter Value
Depth to Groundwater, during current explorations (feet bgs) 18.2-38.0 Depth to Groundwater, during Design Earthquake (feet bgs) 18.2-20.0 Design Peak Ground Acceleration 1.03g
Predominant Earthquake Moment Magnitude, Mw 7.86
Factor of Safety for Liquefaction Triggering 1.3
Based on our analyses, we conclude that the site is underlain by liquefiable soil layers, expected to be subject to between 1 to 2½ inches of vertical settlement under free-field conditions (i.e., without consideration of proposed loads). Approximately half of the estimated vertical settlement is anticipated to occur within the upper 20 feet bgs, under cyclic densification of the dry soils, and be on the order of nil up to 1½ inches. A second liquefiable layer was identified between about 20 and 40 feet and is below the design groundwater elevation, with total estimated settlements within this layer of about ½ to 1 inch. Total liquefiable settlements range from ½ to 2½ inches, as shown in Table VI – Estimated Liquefaction Settlement. Differential settlement is estimated to be on the order of ¼ to 1¼ inches. Of note, several of the CPTs performed by others are included for information but do not extend all through the liquefiable soils and therefore do not capture a full evaluation of liquefaction potential.
Specially, those CPTs that were advanced to less than about 40 feet may appear to under report the settlement potential.
15 TABLE VI
Estimated Liquefaction Settlement
Exploration No. Location
Maximum
Exploration
Depth
(ft)
Estimated
Liquefaction
Settlement
(inches)
Estimated
Cyclic
Densification
Settlement
(inches)
Estimated Total
Seismic
Settlement
(inches)
CPT-1
Residential
43.9 0.9 0.1-1.0 1.0-1.9
CPT-2 42.5 0.7 0.1-0.8 0.8-1.5
CPT-3 43.2 0.5 0.2-1.6 0.7-2.1
CPT-4 46.6 0.2 0.1-0.9 0.3-1.1
CPT-9 R&D
Building 1
28.9 0
1 0 01
CPT-10 44.2 0.3 0.2 0.5
CPT-11 Parking
Structure 19.6 (2.) 0 0
2 CPT-13
R&D
Building 3
30.6 0
1 0 01
CPT-15 23.9 0
1 0 01
CPT-16 24.7 0
1 0 01
SCPT-1
R&D
Building 2
0-50 0.9 0.9-1.6 1.8-2.5
0-79.9 0.93 0.9-1.6 1.8-2.53
Notes:
1) CPTs have limited depths of exploration and reflect the cyclic densification, but only include a partial liquefaction evaluation. 2) CPTs have limited depths of exploration and reflect the cyclic densification but do not include any liquefaction evaluation. 3) No additional liquefaction settlement estimated from depth 50 to 79.9 feet.
6.1.1 Lateral Spreading
Lateral spreading is a potential hazard commonly associated with liquefaction where extensive ground cracking and settlement occurs as a response to lateral migration of subsurface liquefiable material.
These phenomena typically occur adjacent to free faces such as slopes and creek channels. The Youd et al. (2001) study was developed using an empirical methodology for the estimation of lateral spread horizontal displacement using a database where the depth from the ground surface to the top of the liquefiable layer is limited to 30 feet. Using that methodology and based on the results of our subsurface exploration program, we conclude that the Site will be relatively flat after construction and upper soils are predominantly composed of stiff clayey soil and dense sandy soil, which will not experience significant liquefaction. Therefore, the potential for lateral spreading to develop is low.
6.1.1 Sand Boils
Following the procedure presented by Ishihara (1985), based on the results of our subsurface exploration program, we judge that the potential for sand boils to develop is moderate due to the liquefiable soils at the Site, especially within the residential area.
6.1.2 Cyclic Densification
Seismically induced compaction or densification of non-saturated granular soil (such as sand above the groundwater table) due to earthquake vibrations can result in settlement of the ground surface. Based on the results of our subsurface exploration program, we estimate that cyclic densification settlements 16 are in the range of ¼ to 2½ inches due to the upper medium dense sandy soil and deep groundwater level, as summarized in Table VI.
6.1.3 Fault Rupture
Historically, ground surface displacements closely follow the trace of geologically young faults. The Site is not within an Earthquake Fault Zone, as defined by the Alquist-Priolo Earthquake Fault Zoning Act, and no known active or potentially active faults exist on the Site (California Department of Conservation, 2021). Based on this information, we conclude the risk of surface faulting and secondary ground failure is low.
6.1.1 Tsunami
The Site is subject to mapping in the California Tsunami Hazard Area of San Mateo County. Based on maps published by the State of California (2021), the Site is located outside of the area predicted to be affected by tsunamis. Therefore, we judge that the potential for a seismically induced wave to impact the site to be nil.
6.2 EXPANSION POTENTIAL
Laboratory test results from the GCI (2016) report indicate that the near-surface fine-grained soils have very low expansion potential. Expansive soil is characterized by their ability to undergo significant volume change (shrink or swell) due to variations in moisture content. Changes in soil moisture content can result from rainfall, landscape irrigation, perched groundwater, drought or other factors. Changes in soil moisture may result in unacceptable settlement or heave of structures, concrete slabs supported on-grade or pavements supported on these materials. For the proposed building, we recommend moisture conditioning of the expansive soil and using a 6-inch layer of “non-expansive” fill under interior concrete slabs-on-grade.
6.3 FOUNDATIONS AND SETTLEMENT
Our subsurface investigation indicates that approximately 1 to 13 feet of fill is present below the asphalt concrete, and aggregate base. In the northern portion of the Site, the subsurface conditions generally consist of interbedded medium dense to dense silty sand or sandy silt and stiff to very stiff sandy lean clay and clayey soils to depths of 20 to 25 feet bgs. The southern half of the Site is mostly underlain by stiff to very stiff clay. However, borings B-4, B-6, and soundings CPT-13 and SCPT-1 encountered silty sand to sandy silt to a depth of about 20 feet bgs, with interbedded sandy lean clay or lean clay layers from approximately 20 to 40 feet bgs, and a lower dense sand layer at about 65 to 80 feet bgs.
The zone of medium dense and potentially liquefiable sand layers is present in the first layer that includes the approximately upper 20 feet of soil and in a second layer that extends between 20 and 40 feet bgs within the north portion (residential) and central portion (R&D Building 2) of the Site. Without mitigation, estimated liquefaction-induced total vertical settlements in these zones reach as much as 1 to 2 inches in the residential area, 2 to 2½ inches at Building 2, and 1 inch or less in the remaining R&D buildings and parking structure areas. Construction of building foundations and slabs over potentially liquefiable soils is also anticipated to result in significant damage and distress under design-level seismic shaking unless the liquefaction risk is mitigated through ground improvement. 17 We judge that the potential for adverse total and differential ground movements can be reduced by supporting the proposed structures on engineered fill or competent native material for the residential area. With the planned excavation for the below grade parking for Building 2, the potential for cyclic densification is reduced.
If the residential (northern portion) development is supported on at least a 10-foot-thick layer of wellcompacted engineered fill or competent, native soil, the settlement concerns for undocumented fill and dry cyclic settlement will be reduced. With this engineering mitigation, the total settlement following a design level seismic event will includes 1 inch of total settlement with about ½ inch of differential settlement over 50 feet or between columns.
Undocumented fill will be removed during the construction of basement parking for Building 1, Foundations for the R&D office Building 1 supported in competent native soil are anticipated to have 1 inch of total settlement and ½ inch of differential settlement over 50 feet or between columns.
If Building 2 is placed near existing grade as currently planned, we anticipate that it will be subject to excessive settlement following a design level event. To mitigate the settlement, we recommend that the subgrade below the existing ground surface be over-excavated 9 feet, the exposed subgrade scarified and recompacted and the excavation backfilled with engineered fill. With this earthwork, the settlement following a design level earthquake will be reduced to less than 1 inch of total settlement and ½ inch of differential settlement over 50 feet or between columns, Alternative, ground improvement elements such as rammed aggregate piers may constructed to transmit the building loads through the loose soil.
To address undocumented fill, foundations for the R&D office Building 3 and the parking structure should rest on at least a 24-inch-thick layer of well-compacted engineered fill but will not require ground improvement if 1 inch of total settlement and ½ inch of differential settlement over 50 feet or between columns is acceptable.
These design criteria are discussed in more detail in the Recommendations section of this report. 18 7. Recommendations
7.1 EARTHWORKS
7.1.1 Site Preparation and Grading
The proposed building and parking lot areas should be cleared of existing pavements, trees, abandoned utilities and other obstructions. The proposed building and parking lot areas should be stripped of soil containing over 3 percent organic matter (if present). We anticipate the excavation for this project can be made using conventional earth-moving equipment.
Near the residential area, borings HA-4, HA-5 and HA-6 encountered fill to depths of about 5 to 13 feet bgs. In the area planned for residential use, boring HA-4 encountered refusal on concrete at a depth of approximately 7 feet bgs. Based on the provided “Topographic Survey” sheet, there is no utility line shown in the vicinity of HA-4. We recommend performing potholing or test pits to expose the unknown concrete substructure or utility at this location.
Existing utilities within the proposed building footprints should be completely removed. Existing utilities within the parking lot areas should be completely removed where appearing at depths of less than 4 feet below the proposed ground surface elevation. Where existing utilities within proposed parking lot areas are deeper than 4 feet below the proposed ground surface, the utilities may either be removed, as described above, or abandoned in place by exposing, cutting, and capping the ends of the lines, and placing cement grout within the lines to fill existing voids. We recommend that abandoned in place lines be grouted in 100-foot linear sections to confirm that grout has fully filled the abandoned pipe.
7.1.2 Subgrade Preparation
The Site should be rough graded to accommodate the proposed grading plan. Recommendations for mitigation of existing fill are presented for each building type below. In proposed building areas, subgrade preparation should extend at least 5 feet beyond the limits of the proposed building slabs and any adjoining flatwork. In exterior concrete slab and pavement areas, subgrade preparation should extend at least 2 feet beyond the limits of these improvements.
We estimate that approximately 1 to 13 feet of undocumented fill is present below the asphalt concrete pavement. The fill thickness within the R&D buildings and parking structure is about 1 foot. Removed fill soils shall be evaluated by the Geotechnical Engineer for possible reuse and placement as engineered fill.
For the residential development, loose or disturbed soil or undocumented fill soils should be overexcavated to a minimum of 9 feet below existing grade or finished pad elevation, whichever is deeper.
The exposed subgrade should be scarified to a depth of at least 12 inches, moisture conditioned and compacted in accordance with the recommendations given in the section entitled “Fill Placement and Compaction.”
For the R&D Building 1, the exposed subgrade should be scarified to a depth of at least 12 inches, moisture conditioned and compacted in accordance with the recommendations given in the section entitled “Fill Placement and Compaction.”
19 For the R&D Building 2, loose or disturbed soil or undocumented fill soils should be over-excavated to a minimum of 9 feet below existing grade or finished pad elevation, whichever is deeper. The exposed subgrade should be scarified to a depth of at least 12 inches, moisture conditioned and compacted in accordance with the recommendations given in the section entitled “Fill Placement and Compaction.” For the R&D Building 3 and the parking structure, loose or disturbed soil or undocumented fill soils should be over-excavated to a minimum of 1 foot below existing grade or finished pad elevation, whichever is deeper. The exposed subgrade should be scarified to a depth of at least 12 inches, moisture conditioned and compacted in accordance with the recommendations given in the section entitled “Fill Placement and Compaction.”
In non-foundation areas that will receive new fills, building loads, and site improvements, such as pavements, sidewalks, and slabs, the exposed soil subgrade should be evaluated by the Geotechnical Engineer. If fill, it should be over-excavated to a minimum of 1 foot below existing grade or finished pad elevation, whichever is deeper. The exposed subgrade should be scarified to a depth of at least 12 inches, moisture conditioned and compacted in accordance with the recommendations given in the section entitled “Fill Placement and Compaction.” If undisturbed, competent native soil, consideration may be given by the Geotechnical Engineer to reduce the over-excavation.
Prepared soil subgrades should be non-yielding when proof-rolled by a fully loaded water truck or equipment of similar weight. Moisture conditioning of subgrade soil should consist of adding water if the soil is too dry and allowing the soil to dry if the soil is too wet. After the subgrades are properly prepared, the areas may be raised to design grades by placement of engineered fill.
7.1.3 Material for Fill
Except for organic laden soil, the on-site soil is suitable for use as general engineered fill if it is free of deleterious matter and satisfies the criteria in Table VII. Soil for use in engineered fill should be inorganic, and free of deleterious materials and hazardous substances. For this project, inorganic soil is soil with an organic content of less than 3 percent by weight or without visible organic matter deemed excessive by Haley & Aldrich.
TABLE VII
General Engineered Fill Grading Requirements
Sieve Size Percentage Passing Sieve
3 inch 100
1½ inch 85-100
7.1.4 Re-Use of On-site Material
Any existing asphalt or aggregate base that is removed during demolition may be suitable to be pulverized and mixed with the underlying base for use as engineered fill if it has an organic content of less than 2 percent by dry weight and meets the requirements presented under the “Material for Fill” section of this report.
20 The processed asphalt concrete/base material may be used as Class 2 Aggregate base if it meets the following requirements from Section 26 of the Caltrans Standard Specifications:
TABLE VIII
Class 2 Aggregate Base Grading Requirements
Sieve Size Percentage Passing
1 inch 100 min.
¾ inch 90-100
No. 4 35-60
No. 30 10-30
No. 200 2-9
Note Quality Requirements:
Sand Equivalent: 25 min R-value: 78 min
Site recycled material may be processed and reused as engineered fill, “non-expansive” fill, or aggregate base if it meets the requirements presented in this report for the specific materials.
7.1.5 Fill Placement and Compaction
Fill materials should be placed and compacted in horizontal lifts, each not exceeding 8 inches in uncompacted thickness. Compaction of fill should be performed by mechanical means only. Due to equipment limitations, thinner lifts may be necessary to achieve the recommended degree of compaction. Placement of fill should be in accordance with Table IX, Summary of Compaction Recommendations.
TABLE IX
Summary of Compaction Recommendations
Area Compaction Recommendations (See Notes 1 through 4) Subgrade Preparation and
Placement of General Engineered
Fill,5Including Imported Nonexpansive Fill
Compact upper 12 inches of subgrade and entire fill to a minimum of 90 percent compaction at near to slightly over optimum moisture content.
Where interior flatwork is exposed to vehicular traffic, compact aggregate base to a minimum of 95 percent compaction at near optimum moisture content.
Trenches6 Compact trench backfill to a minimum of 90 percent compaction at near to slightly over optimum moisture. Where trenches will be under the pavement section, flatwork, or other improvements, the upper 12 inches, measured from finished grade of the trench backfill should be compacted to a minimum of 95 percent compaction.
Exterior Flatwork Compact upper 12 inches of subgrade to a minimum of 90 percent compaction at near to slightly over optimum moisture content. Compact aggregate base to a minimum of 90 percent compaction at or above optimum moisture content. Where exterior flatwork is exposed to vehicular traffic, compact aggregate base to a minimum of 95 percent compaction at near optimum moisture content.
Paved Areas Compact upper 12 inches of subgrade to a minimum of 95 percent compaction at near to slightly over optimum moisture content. Compact aggregate baserock to a minimum of 95 percent compaction at near optimum moisture content.
Notes:
1) Depths are below finished subgrade elevation.
21 2) All compaction requirements refer to relative compaction as a percentage of the laboratory standard described by ASTM D-1557 (latest version). All lifts to be compacted shall be a maximum of 8 inches loose thickness. 3) All compacted surfaces, such as fills, subgrades, and backfills need to be firm and stable, and should be unyielding under compaction equipment.
4) Where fills, such as backfill placement after removal of existing underground utility lines, are greater than 7 feet in depth, the portion of the fill deeper than 7 feet should be compacted to a minimum of 95 percent compaction. 5) Includes building pads.
6) In landscaping areas, this percent compaction in trenches may be reduced to 85 percent. Water jetting or flooding to obtain compaction of backfill should not be permitted.
7.1.6 Weak or Wet Subgrade Mitigation
GCI (2016) reported groundwater at depths ranging from 31 to 38 feet within their borings and approximately 20 feet within their CPTs during their exploration in September 2014. GES (2021) encountered groundwater at a depth of 20 feet in the additional CPTs in late October 2021. The depth to groundwater was at approximately 18 feet bgs during our subsurface explorations in mid-February 2022 and may fluctuate over time. Excavations for foundations, utilities, and other improvements may encounter weak or wet soil conditions depending on the depths and elevations of these features. If weak or wet soil subgrade is encountered during grading and adequate compaction cannot be achieved, the geotechnical engineer should be notified immediately to assess the condition of the weak or wet subgrade and provide site-specific recommendations for stabilizing and/or repairing the exposed subgrade. Potential subgrade repair options include:
Over-excavating and removing the weak or wet soil and replacing it with select non-expansive fill underlain by geotextile tensile fabric (Mirafi 500X or equivalent). Stabilizing the exposed subgrade by thoroughly blending a lime or cement admixture into the weak or wet soil at a concentration of approximately 5 percent of dry weight of soil being treated, and subsequently compacting the treated subgrade to at least 90 percent relative compaction.
7.1.7 Underground Utilities
Excavations for utility trenches can be made with a backhoe. All trenches should conform to the current Cal/OSHA requirements. Backfill for utility trenches and other excavations is also considered fill, and it should be compacted according to the recommendations presented in the section “Fill Placement and Compaction.” If imported clean sand or gravel is used as backfill, it should be mechanically compacted to at least 95 percent relative compaction. Jetting of trench backfill should not be permitted. Special care should be taken when backfilling utility trenches in pavement areas. Poor compaction may cause excessive settlements, resulting in damage to the pavement section.
Underground utilities should be located above a 1.5:1 (horizontal to vertical) plane projected downward from the bottom of the new footings to avoid undermining the footings during the excavation of the utility trench.
Pipes or conduits should be supported on bedding material with a thickness equal to D/4 (with D equal to the outside diameter of the pipe) or 4 inches of sand or fine non-angular gravel below the pipe, whichever is greater. After the pipes and conduits are tested, inspected (if required) and approved, they should be covered to a minimum depth of 6 inches with sand or fine non-angular gravel, which should be mechanically tamped.
22 Soil excavated from utility trenches may require moisture-conditioning (drying) prior to reusing the material as compacted on-site general fill. Although not anticipated, excavations extending below groundwater will require dewatering. Dewatering should lower the groundwater level to a minimum of 2 feet below the bottom of the excavation. If the soil exposed in the bottom of the excavation is soft or wet, it will be necessary to over-excavate the soil and replace it with crushed rock to create a working platform. The depth of over-excavation should be determined in the field at the time of construction; but for planning purposes, a depth of 12 inches may be assumed.
7.2 FOUNDATIONS
R&D office Building 1, Building 3, and the parking structure may be supported on shallow foundations without ground improvement. Ground improvement or over-excavation is required under the shallow foundations for the residential building and R&D Building 2.
The footing excavations should be free of standing water, debris, and disturbed materials prior to placing concrete. The bottoms and sides of the footing excavations should be maintained in a moist condition until concrete is placed. As the Geotechnical Engineer, Haley & Aldrich should confirm footing excavations are acceptable prior to placement of reinforcing steel and concrete. Any loose or soft soil exposed beneath footing excavations should be removed, and the resulting over-excavations should be backfilled with well-compacted select general fill in accordance with the “Fill Placement and Compaction” section of this report. Alternatively, the over-excavations may be backfilled with lean concrete or sand/cement slurry with an unconfined compression strength of at least 50 pounds per square inch (psi).
7.2.1 Shallow Foundations without Ground Improvement
Shallow foundations at the residential buildings and R&D Building 2 may be designed and constructed to bear on a 10-foot-thick (minimum) layer of engineered fill or competent native material, without the need for performing ground improvement on underlying soils. Shallow foundations at the R&D office Building 1 may be designed and constructed to bear on a competent native soil without the need for performing ground improvement on underlying soils. Building 3, and the parking structure may be designed and constructed to bear on a 2-foot-thick (minimum) layer of engineered fill, without the need for performing ground improvement on underlying soils. The lateral limits of the fill subgrade below the foundations should extend at least 5 feet beyond the footprint of each proposed foundation. The condition of the fill exposed at the bottoms of the proposed isolated and continuous footings should be observed by Haley & Aldrich. The 10- and 2-foot thickness of engineered fill may include 12 inches of over-excavated and recompacted subgrade as described in Table IX in the “Fill Placement and Compaction” section. The resulting excavation may then be backfilled with engineered fill, lean concrete, or controlled density fill.
Continuous footings should be at least 2 feet wide and isolated footings should be a minimum of 5 feet square, respectively. Footings should extend to a depth of at least 24 inches below the bottom of the building floor slab or 24 inches below the adjacent outside grade, whichever is lower.
Shallow spread footings with minimum dimensions and subgrade preparation performed as described above may be designed using an allowable dead plus live load bearing capacity of 3,500 pounds per square foot (psf). Where the buildings are supported on a minimum of 10 feet of engineered fill, this 23 may be increased to 5,000 psf. This value contains a factor of safety of at least 2 and may be increased by one-third for total loads, including wind or seismic forces.
Lateral loads may be resisted by a combination of passive pressure on the embedded vertical faces of the footings and friction between the bottoms of the footings and the supporting soil. For passive resistance, we recommend using an equivalent fluid weight of 280 pounds per cubic foot (pcf) for footings embedded in compacted fill; the upper foot of soil should be ignored unless it is confined by a concrete slab or pavement. Frictional resistance should be computed using a base friction coefficient of
0.35. The passive pressure is unfactored and does not include lateral resistance contributions from the adjacent concrete slabs-on-grade. Uplift resistance may be computed based on the dead weight of the planned foundation elements.
7.2.2 Shallow Foundations over Ground Improvement
If the R&D Building 2 does not have a basement, the foundations should bear on a ground improvement system or elements or deep engineered fill. Several ground improvement approaches may be appropriate for liquefaction hazard mitigation, including compaction grouting, deep soil mixing, and stone columns. Ground improvement systems are designed and constructed by specialty contractors with proprietary equipment and/or proprietary construction techniques. A specialty contractor should be consulted to provide one or more suitable liquefaction mitigation approaches for evaluation by the design team.
The detailed final design and installation of ground improvement is typically performed by specialty subcontractors, in accordance with performance criteria established by the Owner’s Geotechnical Engineer (Haley & Aldrich). Proposals by prospective specialty contractors bidding the work will be reviewed by the Geotechnical Engineer and the Structural Engineer for suitability of the proposed system and compliance with the project requirements.
The following design criteria are recommended for footings installed after ground improvement is performed:
Design footings using a minimum allowable bearing pressure of 5 kips per square foot (ksf). The allowable bearing pressure used for final footing design should be verified by the ground improvement designer but should be limited to a maximum bearing pressure of 10 ksf. Design footings to have a least lateral dimension of 24 inches or greater. Locate bottoms of footings at least 24 inches below the bottom of the adjacent ground floor slab or the adjacent grade, whichever is deeper.
Ground improvement elements should not be relied upon for uplift resistance unless permanent hold-down elements are incorporated into the design of the ground improvement elements.
Haley & Aldrich recommends using an average modulus of vertical subgrade reaction value of 55 pounds per cubic inch (pci) for evaluating shallow foundations on improved ground pending confirmation from the specialty contractor.
Lateral loads can be resisted through a combination of friction along the tops of the ground improvement elements and passive soil resistance against the embedded vertical faces of the stiffened shallow foundations. For computing frictional resistance, Haley & Aldrich recommends using a friction factor of 0.55 times the compressive load applied against the load transfer pad of the ground improvement elements.
24 Additional lateral load resistance can be obtained by passive resistance acting against the embedded vertical faces of the proposed shallow foundations. To compute passive resistance, Haley & Aldrich recommends using an allowable equivalent fluid weight of 280 pcf applied against embedded faces of the shallow foundation elements. These values are unfactored, a factor of safety has not been applied. The upper 1 foot of soil should be ignored unless the soil adjacent to the shallow foundations are covered by slabs or pavements. Design footings to bear below a reference line drawn upward and outward on a 1.5 horizontal to 1 vertical (1.5H:1V) slope from the bottom of any adjacent utilities or other underground structures including drainage basins.
7.2.3 Ground Improvement
Ground improvement systems are designed and constructed by specialty contractors with proprietary equipment and/or proprietary construction techniques. Therefore, Haley & Aldrich can only provide preliminary recommendations in this report. Final ground improvement design-build drawings, calculations, and specifications should be provided by the ground improvement contractor and reviewed and approved by Haley & Aldrich. Typically ground improvement options to mitigate the seismic hazards encountered at the project site include rigid inclusions using non-driven, non-vibratory methods, such as drilled displacement elements consisting of columns of unreinforced sand-cement slurry and/or lean concrete (i.e., rigid inclusions), or deep soil mix (DSM) columns, which consist of cementitious grout that is blended into the underlying soil to form soil-cement columns.
Recommendations specific to ground improvement design are provided as follows:
The ground improvement design should be developed to limit settlements of footings under design working loads due to compression of the improved soil to 1 inch or less (including settlement in underlying soil from which ground improvements derive their support), with a maximum differential settlement over a 50-foot distance of ½ inch. Settlement calculations should be provided in the Contractor’s design submittals. For design purposes, it can be assumed that about one-half of foundation settlements will likely occur during construction as structure dead loads are placed on the foundations. The remaining settlements are anticipated to occur within about 5 years after building construction unless additional loads are added to the currently planned structure.
The ground improvement design should be capable of transferring the building loads below soil layers that are liquefiable and into competent cohesive soils encountered at depths of about 35 to 40 feet below the existing grade. This depth should be confirmed with the Ground Improvement contractor and Haley & Aldrich during design development. For Building 2, at the owner’s decision, the ground improvement does not need to be designed to provide support to slabs-on-grade if settlement following a design-level seismic event is acceptable.
The ground improvement does not need to be designed to provide support for sub-floor utilities.
A footing pad or load transfer platform must be provided as a transition layer between the ground improvement elements and the bottoms of footings. The thickness and composition of the footing pad should consider the element capacity, stresses induced on the footing bases, compression of the pad, and other factors.
25 Other details of the ground improvement including footing pad requirements should be outlined in the project specifications and specialty contractors’ proposals. We recommend a minimum footing pad thickness of 8 inches, assuming it is constructed of crushed stone or similar aggregate/granular material. Detailed design submittals should be provided for the ground improvement system, for review by Haley & Aldrich.
Testing (modulus and/or load testing) should be performed on ground improvement elements to confirm the design assumptions. A minimum of three elements will need to be tested prior to the start of production installation. The elements will need to be taken up to a minimum of 2 times the allowable design capacities.
The ground improvement contractor(s) should provide: 1) design capacity calculations associated with their proprietary ground improvement system(s); 2) a plan showing the ground improvement element locations and identification numbers; 3) details showing the material specifications, depths and diameters of the ground improvement elements; 4) details showing the material specifications, locations and thickness of the load transfer layers; and 5) details and descriptions of the load testing program and the quality control/quality assurance program used to confirm the design capacities and settlement behavior of the ground improvement elements.
7.3 SLABS-ON-GRADE
Concrete slabs are anticipated to consist of floor slabs, loading docks, and exterior walkways. The floor slabs can be supported on grade. The exposed subgrade soil should be moisture conditioned and recompacted as discussed in the “Fill Placement and Compaction” section of this report.
7.3.1 Floor Slabs
The interior concrete floor slab thickness and reinforcement should be provided by the project structural engineer. As a minimum, the floor slab should be directly underlain by at least a 6-inch-thick layer of Class 2 aggregate base or a 6-inch-thick water vapor retarder system, as described below. The soil subgrade beneath the interior floor slab system should be prepared and compacted, as described in the section “Fill Placement and Compaction.” The subgrade should not be allowed to dry during construction. If the previously compacted soil subgrade is disturbed during foundation and/or utility excavation, the subgrade should be scarified, moisture-conditioned, and rerolled to provide a firm, unyielding surface prior to placement of the capillary break material or casting the concrete floor.
If moisture transmission through the slab is acceptable or if the slab is subject to vehicle loading such as at the parking structure, the slab-on-grade floor may be placed over a 6-inch-thick layer of Caltrans Class 2 Aggregate Base that has been compacted to at least 95 percent relative compaction.
In other locations, to reduce water moisture transmission through the floor slab, we recommend installing a capillary moisture break and a minimum 15-mil-thick Class C water vapor retarder beneath the floor. Typically, finished spaces with slab-on-grade floors, such as offices, will utilize capillary moisture breaks and vapor retarders to reduce the potential for water vapor transmission through the floor, which can adversely impact flooring materials and carpeting.
A capillary moisture break consists of at least 4 inches of clean, free-draining gravel or crushed rock capped, overlain by a vapor retarder, and capped with 2 inches of clean sand. The vapor retarder should be placed in general accordance with the requirements of ASTM E1643. These requirements include 26 overlapping seams by 6 inches, taping seams, and sealing penetrations in the vapor retarder. The particle size of the gravel/crushed rock and sand should meet the gradation requirements presented in Table X.
TABLE X
Gradation Requirements for Capillary Moisture Break
Sieve Size Percentage Passing Sieve
Gravel or Crushed Rock
1 inch 90-100
3/4 inch 30-100
1/2 inch 5-25
3/8 inch 0-6
Sand
No. 4 100
No. 200 0-5
Concrete mixes with high water/cement (w/c) ratios will result in excess water in the concrete, which increases the cure time and may result in excessive vapor transmission through the slab. Therefore, concrete for the floor slab should have a low w/c ratio of less than 0.50. If approved by the project structural engineer, the sand can be eliminated beneath the slabs-on-grade and the concrete can be placed directly over the vapor retarder, provided the w/c ratio of the concrete does not exceed 0.45 and water is not added in the field. If necessary, workability should be increased by adding plasticizers. In addition, the slab should be properly cured.
Before the floor covering is placed, the contractor should check that the concrete surface and the moisture emission levels (if emission testing is required) meet the manufacturer’s requirements.
7.3.2 Exterior Flatwork
Exterior flatwork may be supported on grade. We recommend that, as a minimum, exterior concrete slabs and pedestrian walkways be designed using 4 inches of concrete. Typically, construction joints are spaced at horizontal distances no greater than 30 times the concrete slab thickness. If there is a conflict between the civil and geotechnical design recommendations for contraction joint spacing, Haley & Aldrich defers to the civil engineer’s recommendations. Where concrete flatwork is to be exposed to vehicle traffic, we recommend that the flatwork be supported on a minimum of 6 inches of Class 2 aggregate baserock. Recommendations for subgrade preparation and aggregate base compaction for concrete slabs and walkways are the same as those we have described in the “Fill Placement and Compaction” section.
7.4 STORMWATER INFILTRATION
Two downhole percolation tests were performed at hand auger boring locations HA-1 and HA-2 within the proposed office building area of the Site (see locations on Figure 2). The test results are presented in Appendix C. Based on our interpretation of the percolation test data, the adjusted long-term infiltration rate for stormwater infiltration features with invert depths at about 2 to 5 feet bgs is on the order of
0.02 to 0.23 inches per hour. The higher value corresponds to the silty sand (SM) encountered in boring HA-1 and the lower value refers to the clayey soil encountered in boring HA-2 and is not representative of the overall site conditions. The adjusted long-term infiltration rates include a factor of safety (CFv) of 27 2 for moderate site variability, and a factor of safety (CFs) of 2 for long-term siltation of infiltration basins. In addition, a reduction factor (Rf) specific to the borehole percolation test method of 13.63 to
13.88 was computed for testing at both locations. The suggested values for these factors are presented in Appendix C. For the design of on-site stormwater infiltration features with inverts positioned within 5 feet bgs, we recommend using a long-term infiltration rate of 0.23 inches per hour.
The effective infiltration rate of finished stormwater infiltration features can vary significantly from the rates estimated from the percolation tests. The following activities may diminish the infiltration rate of proposed stormwater features and should be avoided:
Placement of artificial fill within the stormwater infiltration feature during grading, especially placement of fill materials with poor drainage properties. Allowing construction runoff containing fine-grained soils to drain into the feature and cause siltation during site grading.
Grading methods that result in smearing or compacting of soils at the feature or basin invert, including compaction by driving of heavy equipment over the area. Design and siting of infiltration features at locations or elevations significantly different from those tested.
We recommend that supplemental in situ infiltration testing be performed at locations of new stormwater infiltration features after site grading has been completed to confirm that grading activities have not affected the long-term infiltration rate of the underlying soils. Supplemental testing may include additional borehole percolation tests, double ring infiltrometer testing, or reduced-scale pit tests.
7.5 SURFACE DRAINAGE
Site grading should provide surface drainage away from the proposed structures and concrete slabs-on-grade to reduce the percolation of water into the underlying soil. Surface water should not be allowed to collect adjacent to structures and along edges of concrete slabs or pavements. Grades should be sloped away from the structures as required in the California Building Code (current edition). Surface water should be directed away from exposed soil slopes. Rainwater on the roof of buildings should be conveyed through gutters, downspouts and closed pipes which discharge directly into the site stormwater collection system or pavement. If discharging onto the pavement, safety of pedestrian traffic should be considered.
7.6 FLEXIBLE PAVEMENT DESIGN
The State of California Resistance (R)-value method for flexible pavement design was used to develop recommendations for pavement sections. The thickness of pavement depends on the R-value of the subgrade soil and the volume of traffic anticipated.
Based on the soil type and plasticity of natural soils encountered below the asphalt concrete and concrete pavement in the borings, we recommend using a design soil subgrade R-value of 20 and relying on the subgrade preparation method discussed in the “Earthworks” section of this report. 28 We assume that flexible pavement throughout the Site will be designed using traffic indexes (TI) ranging from 4.5 to 9.0. Design sections for flexible pavement sections bearing directly over compacted native soil (R-value = 20), are presented in Table XI.
TABLE XI
Flexible Pavement Design (R-Value = 20)
Traffic
Index
Asphalt
Concrete
(inches)
Class 2
Aggregate Base
(inches)
Total
(inches)
4.5 2.5 7.0 9.5
5.0 2.5 8.5 11.0
6.0 3.0 10.5 13.5
7.0 4.0 12.0 16.0
8.0 4.5 14.5 19.0
9.0 5.5 16 21.5
We recommend that the subgrade soil, over which the pavement sections are to be placed, be moisture conditioned and compacted according to the recommendations in the “Fill Placement and Compaction” section of this report. Subgrade preparation should extend a minimum of 2 feet laterally beyond the back of curb or edge of pavement. Paved areas should be sloped and drainage gradients maintained to carry all surface water to appropriate collection points. Surface water ponding should not be allowed anywhere on the Site during or after construction. We recommend that the pavement section be isolated from non-developed areas and areas of intrusion of irrigation water from landscaped areas.
Concrete curbs should extend a minimum of 2 inches below the baserock and into the subgrade to provide a barrier against drying of the subgrade soil, and a reduction of migration of landscape water into the pavement section.
7.7 RIGID PAVEMENT DESIGN
Rigid pavement design was performed in conformance with the AASHTO 1993 design method, including vehicle loads calibrated to a standard equivalent single axle load of 18,000 pounds and a maximum tandem axle load of 32,000 pounds. The thickness of rigid pavement depends on the R-value of the subgrade soil and the volume of traffic anticipated. For this site, as stated in the “Flexible Pavement Design” section, we assume a design R-value of 20 for the existing subgrade. We assume that rigid pavements throughout the site will be designed using TI up to 10.0. Based on these design parameters, we recommend using the pavement designs presented on Table XII. 29 TABLE XII
Rigid Pavement Design
Traffic
Index
Portland Cement
Concrete
(inches)
Class 2 Aggregate
Base
(inches)
Total
(inches)
≤7.0 6.0 6.0 12.0
7.0 – 9.0 8.5 6.0 14.5
9.0 – 10.0 10.0 6.0 16.0
Notes:
1) Class 2 Aggregate Base to be placed over the improved subgrade.
The modulus of rupture of the concrete should be at least 600 psi at 28 days and the unconfined compressive strength of the concrete should be at least 3,500 psi at 28 days. Contraction joints should be constructed at a 12.5-foot spacing for the 6-inch-thick concrete pavement and 15-foot spacing for the 7-inch-thick concrete pavement. Where the outer edge of a concrete pavement meets asphalt pavement, the concrete slab should be thickened by 50 percent at a taper not to exceed a slope of 1 in
10. For better long-term performance, consideration should be given to reinforcing the slab with a minimum of No. 3 bars at 18-inch spacing in both directions. If there is a conflict between the civil and geotechnical design recommendations for contraction joint spacing or slab reinforcement, we defer to the civil engineer’s recommendations. Recommendations for subgrade preparation and aggregate base compaction for concrete pavements are provided in the “Fill Placement and Compaction” section of this report.
7.8 TEMPORARY EXCAVATION SHORING
Temporary shoring walls will be required to support the vertical sides of the deep excavation for Building 1. The shoring system should be designed to provide temporary lateral support for the excavation while ensuring safety and stability of the buildings, utilities, and other infrastructure adjacent to the excavation. Although not anticipated, if temporary shoring will act as a groundwater cut-off, embedment depth may be deeper than what is needed for the support of excavation. Final toe depths should be further reviewed and selected by the design-build shoring contractor.
We understand that a soldier beam and lagging system with internal bracing is the preferred method of shoring for this project due to constraints from the adjacent El Camino Real. However, we have included recommendations for a solider pile wall with tiebacks for completeness; the pressure diagram reflects internal bracing.
The following sections provide geotechnical engineering criteria for the design of the shoring system described above, including lateral soil and water pressures. Recommendations for the shoring system rely on assumptions that are specific to the particular shoring system as it is applied to this project; Haley & Aldrich should be consulted if alternative shoring systems are proposed.
7.8.1 General Considerations
We recommend that the shoring be designed by a professional structural engineer registered in the State of California. We also recommend that we be given the opportunity to review the proposed shoring design before construction.
30 This report is not intended to provide specific criteria for the contractor’s construction means and methods. It should be the responsibility of the shoring contractor to verify actual ground conditions at the Site and determine the construction means, methods, and procedures needed to install an appropriate shoring system.
7.8.2 Lateral Earth Pressures
The design of the temporary shoring will require supplemental lateral support in order to limit wall movements and protect adjacent improvements. Supplemental lateral support may be provided through an exterior system of tie-back soil anchors and/or internal bracing consisting of corner braces, cross-lot braces, or rakers. These supplemental lateral support systems can transfer vertical compression and tension loads to the proposed shoring system. The embedment of the shoring wall must be sufficient to provide lateral stability for the shoring system, as well as vertical stability. Vertical loads can be resisted by skin friction along the embedded portions of the wall (below the base of the excavation) and by end bearing.
The typical design parameters for the shoring system designed to resist active and at-rest earth pressure conditions are presented on Figure 5.
It should be noted that some deformation is expected in all shoring systems during construction. The magnitude of movement is controlled by many factors, including the type of system used and the contractor's skill in installing the shoring system. For a typical shoring system designed for active earth pressure conditions, we judge that lateral movements will be within ordinarily accepted limits of up to about 0.002 to 0.004 times the height of the shoring system, which corresponds to less than ½ inch to just over 1 inch for the proposed excavation. However, if the shoring system needs to be designed to greatly limit lateral movements, then the shoring system should be designed for at-rest earth pressures.
Survey points should be established on the shoring, adjacent streets and sidewalks, and neighboring buildings to monitor the movement of these features during and immediately after construction.
Settlement-sensitive structures within the zone of deformation should be underpinned, or the shoring system supporting the structure should be designed considering surcharge loading from the existing vehicular traffic. Settlement-sensitive utilities located adjacent to the proposed shoring walls should be identified and acceptable settlement criteria confirmed with the utility owner. If settlement-sensitive utilities are present, Haley & Aldrich should be consulted to evaluate the impact of the shoring system.
We make the following recommendations regarding lateral earth pressures for the shoring system:
Compute the lateral earth pressures, hydrostatic water pressures, and uniform construction/traffic surcharges for a system with multiple rows of tieback or interior bracing support using apparent earth pressures given on Figure 5. The lateral pressures presented on Figure 5 are based on a level backslope behind the walls.
The shoring must be designed to carry the bending and shear stresses caused by the restrained soil, groundwater, tiebacks, and external or internal supports, if applicable, such as the vertical load resulting from down-angle tieback anchors. The stresses can be calculated from the apparent earth pressure diagrams provided on Figure 5 with additional surcharge pressures as described previously. Shoring elements must be embedded deeply enough to resist these loads, provide a kickout resistance for the portion of the wall below the lowest support, and provide groundwater cut-off to prevent base heave. 31 We recommend that the following criteria be used to establish shoring elevations:
Vertical shoring elements may be designed with allowable end bearing of 5 ksf. Vertical shoring elements may be designed with allowable axial skin friction of 0.35 ksf below the base of excavation. Neglect skin friction above the base of the excavation. Steel soldier pile sections should be embedded at least 10 feet below the base of excavation.
This embedment should consider an excavation depth that accounts for over-excavation required for foundations, elevator pits, and installation of the dewatering system (if used). The shoring wall and steel piles should be designed for bending moments and shear imposed by tieback loads or bracing and recommended earth pressures. For design against kickout, compute the lateral resistance on the basis of the passive pressure presented on Figure 5.
The shoring wall should have sufficient bond strength such that the loads from the steel soldier piles can be transferred to the wall below the base of the excavation.
7.8.3 Shoring Installation
The above recommendations are based on proper installation of the shoring sections, as discussed below.
Changes in the soil conditions relative to what we have assumed for our recommendations may cause the shoring system to perform poorly. Softer end bearing conditions combined with the vertical component of the inclined tieback load may result in settlements that would cause partial destressing of the tiebacks and excessive lateral movement of the shoring system. We recommend a Haley & Aldrich representative observe trenching and cut-off wall installation, to determine if unexpected subsurface conditions are encountered, so that construction methods can be adjusted accordingly, if necessary.
We make the following recommendations regarding shoring wall installation:
The contractor should be prepared to tremie concrete from the bottom of the shoring cut-off wall excavation to displace groundwater or drilling slurry used to maintain an open excavation. Concrete, slurry, or soil-cement samples should be collected and tested throughout installation to test for uniformity of mixing and required compressive strength. The contractor should be required to submit a plan describing how leaks in the system, such as discontinuities in the wall and tieback penetrations will be prevented, or otherwise mitigated and repaired.
7.8.4 Design and Construction of Tiebacks
Although not anticipated, tieback anchors may be used for external lateral support of the shoring wall and embedded steel beams. If used, Haley & Aldrich will need to provide supplemental recommendations.
32 7.9 RETAINING WALLS
Retaining walls are planned along El Camino Real where the road slopes down toward the north. The retaining walls will be two-tier with each tier about 7 feet tall. The details of the wall design are still under development. Retaining walls are anticipated for the one-level basement of the R&D office Building 1 adjacent to the tiered retaining walls. We understand the depth of the one-level basement including bottom of the excavation will be on the order of 11.5 to 23.5 feet deep and that the bottom of the excavation will be at about elevation 28.5 feet.
Permanent walls constructed flush against temporary shoring systems such as soldier piles and tiebacks or internal bracing should be designed for at-rest lateral soil pressures recommended for multiplebraced tieback walls based on the local standard of practice. In addition to the pressures shown on Figure 5 – Temporary Lateral Earth Pressures for Excavation, permanent below-grade walls should also be designed to resist the following loads and pressures:
Lateral pressures caused by earthquakes should be added to the pressures modeled using a uniform seismic increment (rectangular distribution) of 15 times the height of the wall in psf, where the height is in feet.
We recommend that a surcharge of 250 psf be applied to the top of the proposed excavation for computations to provide some allowance for possible surface surcharge load behind the basement wall, such as light vehicles or small material stockpiles.
These additional loads would be additive to the soil pressure calculated for permanent foundation walls.
Coordination with the shoring engineer will be required to ensure consistency.
To protect against moisture migration, below-grade walls should be waterproofed and water stops should be placed at all construction joints. Surface grades above the wall should be sloped away from the face of the building.
The above lateral design pressures are based on fully drained walls. Even though the retaining walls will be above the groundwater table, water can still accumulate behind the walls from other sources, such as rainfall, irrigation, and broken water lines. Prefabricated drainage material (such as Miradrain® or an approved alternate) may be used behind below-grade and retaining walls. Prefabricated drainage material should be installed in accordance with the manufacturer's recommendations.
As an alternative to prefabricated drainage material, a drain rock layer may be used. The drain rock layer should 1 to 2 feet thick and extend to within 1 foot of the ground surface. Four-inch diameter perforated plastic pipe should be installed (with the perforations facing down) along the base of the walls on a 4-inch-thick bed of drain rock. The pipe should be sloped to drain by gravity to a sump or other drainage facility. Weep holes may also be used if water seepage is permissible in the structure.
The weep holes should be a minimum of 3 inches in diameter located at no more than 10 feet apart, and a screen placed at the back of the holes if drain rock is used.
Drain rock should conform to Caltrans Class 2 permeable material. Alternatively, locally available, clean, ½ to ¾ inch maximum size crushed rock or gravel could be used, provided it is encapsulated in a nonwoven geotextile filter fabric, such as Mirafi® 140N or an approved alternative. 33 Although not likely, even with the back-drain system, localized wet spots may occur in the walls. If this is undesirable, then the wall should be waterproofed.
7.10 TEMPORARY DEWATERING
Based on the current project understanding, we anticipate that excavations will not encounter groundwater at the Site. However, perched water may be encountered during excavation. As such, temporary dewatering may be required.
Temporary dewatering for construction is the responsibility of the Contractor. The selection of equipment and methods of dewatering should be left up to the Contractor, who should be aware that modifications to the dewatering system may be required during construction depending on the conditions encountered. The dewatering method selected should have minimal impact on the groundwater level surrounding the proposed excavation. We recommend that temporary dewatering of the Site be carried out in such a manner as to maintain the groundwater a minimum of 3 feet below the excavations for utilities or structures.
As a minimum, previsions should be made to ensure that conventional sump pumps used in typical trenching and excavation projects are available during construction in case groundwater is found to be higher than observed during our investigation, and/or if substantial runoff water accumulates within the excavation as a result of wet weather conditions.
7.11 CORROSION POTENTIAL
GCI (2016) performed corrosivity characteristic tests on five selected samples from borings B-2, B-4, B-6, B-7, and B-8 at depths ranging from 1.5 to 4 feet. GES (2021) concluded that samples are classified as “negligible to low corrosive.” Haley & Aldrich also performed corrosivity testing on two samples at depths of 2 and 5 feet at borings HA-4 and HA-6. Based on resistivity measurements and previous data, we conclude the soils are considered “slightly corrosive” to buried iron, steel, cast iron, ductile iron, galvanized steel and dielectric coated steel or iron. Where these materials are used on-site, they should be properly protected against corrosion. All buried metallic pressure piping, such as ductile iron firewater pipelines, should be protected against corrosion. The tested samples indicate that on-site soils do not pose a hazard to reinforced concrete structures and cement mortar-coated steel. A summary of corrosivity analysis results is provided in Table XIII.
TABLE XIII
Corrosivity Analysis Results
Sample No. pH
Min. Resistivity
(ohms-cm)
Chloride
(mg/kg)
Sulfate
(mg/kg)
B-2, B-4, B-6, B-7,
and B-8 @ 1.5’-4’*
7.4 1,908 29 93
HA-4-C @ 2’ 7.3 3,700 N.D. 21
HA-6-C @ 5’ 7.3 2,000 N.D. 62
Notes:
1) Asterisk (*) refers to data from the Geosphere Consultants, Inc. report (GCI, 2016). 34 8. Supplemental Geotechnical Services
The final project plans and specifications should be reviewed by Haley & Aldrich prior to construction to check that they are in general conformance with the intent of our recommendations. During construction, we should observe and document the installation of foundations, observe the condition and test the compaction of any fill placed at the Site, and observe trenching and cut-off wall installation.
These observations will allow us to check that the contractor’s work conforms to the geotechnical aspects of the plans and specifications and ensure that the foundation system and paved areas are constructed in accordance with our design recommendations. 35 9. Limitations
This report has been prepared for specific application to the proposed construction as understood at this time. In the event that changes in the nature, design, or location of the project are planned, the conclusions and recommendations contained in this report should not be considered valid, unless the changes are reviewed by Haley & Aldrich and the conclusions of this report modified or verified in writing.
The geotechnical analyses and recommendations are based, in part, upon the data obtained from the referenced subsurface exploration. The nature and extent of variations between explorations may not become evident until construction. If variations appear at that time, it may be necessary to re-evaluate the recommendations of this report.
This report is prepared for the exclusive use of SteelWave, LLC and their subconsultants in pursuit of the proposed development in South San Francisco, California. There are no intended beneficiaries other than SteelWave, LLC and their subconsultants. Haley & Aldrich shall owe no duty whatsoever to any other person or entity on account of the Agreement or the report. Use of this report by any person or entity other than SteelWave, LLC and their subconsultants for any purpose whatsoever is expressly forbidden unless such other person or entity obtains written authorization from SteelWave, LLC and Haley & Aldrich. Use of this report by such other person or entity without the written authorization of SteelWave, LLC and Haley & Aldrich shall be at such other person’s or entity’s sole risk and shall be without legal exposure or liability to Haley & Aldrich. 36 References
1. American Association of State Highway and Transportation Officials (AASHTO), 1993. Design of Pavement Structures. 1993.
2. American Society of Civil Engineers (ASCE), 2017. Minimum design loads and associated criteria for buildings and other structures: ASCE/SEI 7-16.
3. ASTM International (ASTM), 2011. “ASTM E1643 Standard Practice for Selection, Design, Installation, and Inspection of Water Vapor Retarders Used in Contact with Earth or Granular Fill Under Concrete Slabs,” Reapproved 2017.
4. ASTM, 2012. ASTM D 1557 - Standard Test Methods for Laboratory Compaction Characteristics of Soil Using Modified Effort (56,000 ft-lbf/ft3 (2,700 kN-m/m3)).
5. Boulanger, R.W. and Idriss, I.M., 2014. CPT and SPT Based Liquefaction Triggering Procedures.
Report No. UCD/CGM-14/01.
6. Brabb, E.E., and Pampeyan, E.H., 1983. Geologic map of San Mateo County, California: U.S.
Geological Survey, Miscellaneous Investigations Series Map I-1257-A, scale 1:62,500.
7. California Building Standards Commission, 2019. California Code of Regulations. Title 24, Volume 2.
8. California Department of Conservation, 2021. Earthquake Zone of Required Investigation. Website:
<https://maps.conservation.ca.gov/>, accessed 28 February 2022.
9. California Department of Water Resources, 2021. Water Data Library (WDL). Website:
<https://wdl.water.ca.gov/waterdatalibrary/Map.aspx>, accessed 28 February 2022.
10. California Geological Survey, 2021. Seismic Hazard Report for the San Francisco South 7.5-Minute Quadrangle, San Mateo County, California. Seismic Hazard Zone Report 133, 2021.
11. Caltrans, 2018. “Standard Specifications”; Published by the Department of Transportation, Section 26 – Aggregate Bases.
12. County of Los Angeles Department of Public Works, 2014. Guidelines for Design, Investigation, and Reporting Low Impact Development Stormwater Infiltration. DPW Administrative Manual GS200.1.
13. Geosphere Consultants, Inc., 2014. “Geotechnical Engineering Study, Centennial Village Mixed-Use Development, 180 El Camino Real, South San Francisco, CA,” Project No. 91-03317-A, dated 31 October 2014 (updated 1 March 2016).
14. Geo-Engineering Solutions, Inc., 2021. “Geotechnical Engineering Study, 180 El Camino Real – Retail Parcel, 180 El Camino Real, South San Francisco, California 94080,” dated 10 November 2021.
15. Ishihara, K.,1985. “Stability of Natural Deposits During Earthquakes,” Proceedings, 11th International Conference on Soil Mechanics and Foundation Engineering, San Francisco. Vol 1, p 321-376.
37 16. Post-Tensioning Institute, 2014. Recommendations for Prestressed Rock and Soil Anchors.
17. Robertson, P.K., Cabal, K.I., 2010. Guide to Cone Penetration Testing for Geotechnical Engineering, 4 th Edition, July.
18. Rockridge Geotechnical, 2020. “Preliminary Geotechnical Study to Support Due Diligence Evaluation, 180 El Camino Real, South San Francisco, California,” Project No. 20-1955, dated 14 December 2020.
19. State of California, 2021. Tsunami Hazard Area Map, San Mateo County. Produced by the California Geological Survey and the California Governor’s Office of Emergency Services, 23 March 2021.
20. Toppozada, T. R., and Borchardt, G., 1998. Re-evaluation of the 1836 ‘‘Hayward fault’’ and the 1838 San Andreas earthquakes. Bulletin of the Seismological Society of America, 88, 140 – 159.
21. USGS, 2021. Quaternary Fault and Fold Database of the United States. Website <https://www.usgs.gov/programs/earthquake-hazards/faults>, accessed 28 February 2022.
22. USGS, 2021. Unified Hazard Tool. Website <https://earthquake.usgs.gov/hazards/interactive/>, accessed 28 February 2022.
23. Working Group on California Earthquake Probabilities (WGCEP), 2015. Uniform California Earthquake Rupture Forecast (Version 3). <http://www.wgcep.org/UCERF3>
24. Youd, T.L., et. al., 2001. Liquefaction Resistance of Soils: Summary Report from the 1996 NCEER and 1998 NCEER/NSF Workshops on Evaluation of Liquefaction Resistance of Soils, American Society of Civil Engineers, Journal of Geotechnical and Geoenvironmental Engineering, Vol. 127, No. 10, October.
FIGURES
CA
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SITE COORDINATES: 37°38'35"N, 122°25'21"W
180 EL CAMINO REAL
SOUTH SAN FRANCISCO, CALIFORNIA
PROJECT LOCUS
FIGURE 1 APPROXIMATE SCALE: 1 IN = 2000 FT
MARCH 2022
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CONE PENETRATION TEST, GEOENGINEERING SOLUTION. INC. (2021)
CONE PENETRATION TEST, GEOSPHERE
CONSULTANT, INC. (2014)
SOIL BORING , GEOSPHERE CONSULTANT,
INC. (2014)
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NOTES
1. ALL LOCATIONS AND DIMENSIONS ARE APPROXIMATE,
2. ASSESSOR PARCEL DATA SOURCE: SAN MATEO COUNTY
3. BASE MAP SOURCE: "PRELIMINARY UTILITY PLAN" PREPARED BY SKIDMORE, OWINGS. & MERRILL LLP, DATED 17 DECEMBER 2021.
4. AERIAL IMAGERY SOURCE: NEARMAP, 29 SEPTEMBER 2021
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,,. \,,.
,,.
,,.
/
,,.
/ �oO�I'-��
Qoa
if
"<'
lJJ
a:
I
(/J
w
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0::
5 _J
0 0
LEGEND
L __ J SITE BOUNDARY
GEOLOGIC UNI T L ALLUVIUM, HOLOCENE (Qha)
ALLUVIUM, EARLY PLEISTOCENE, (Qoa)
L ARTIFICIAL FILL (af)
HILLSLOPE DISPOSITS, QUATERNARY. (Qsl)
NOTES
1. ALL LOCATIONS AND DIMENSIONS ARE APPROXIMATE.
2. GEOLOGIC UNIT SOURCE= UNITED STATES GEOLOGIC SURVEY
(USGS), 2022
3. ASSESSOR PARCEL DATA SOURCE: SAN MATEO COUNTY
4. AERIAL IMAGERY SOURCE: NEARMAP, 29 SEPTEMBER 2021
0 �ICH
500
SCALE IN FEET
180 EL CAMINO REAL
SOUTH SAN FRANCISCO, CALIFORNIA
1,000
REGIONAL GEOLOGIC MAP
MARCH 2022 FIGURE 3
@
@
@
@
@
@
@
@
@
@
@
@
@
@
@
@
?!"
?!"
?!"
?!"
?!"
?!"
?!"
?!"
A@
A@
A@
?!¤
?!
?!
?!
?!
?!
?!
?!"
Qha
Qoa
Qoa
RAMONA AVE
FRANCISCO DR
EL CAMINO REAL
EL CORTEZ AVE
HAZELWOOD DR
MANOR DR
NORTHWOOD DR
HUNTINGTON AVE
KENWOOD WAY
BRENTWOOD DR
ROCKWOOD DR
NOOR AVE
S SPRUCE AVE
CPT-1
CPT-2
CPT-3
CPT-4
CPT-5
CPT-6
CPT-7
CPT-8
CPT-9
CPT-10
CPT-11
CPT-12
CPT-13
CPT-14
CPT-15
CPT-16
B-1
B-2
B-3
B-4
B-5
B-6
B-7
B-8
CPT-1A
CPT-2
CPT-3A
SCPT-1
HA-1
HA-2
HA-3
HA-4
HA-5
HA-6
LB-1
LEGEND
?!
SOIL BORING OR INFILTRATION TEST,
HALEY & ALDRICH (2022)
?!¤
SEISMIC CONE PENETRATION TEST,
HALEY & ALDRICH (2022)
A@
CONE PENETRATION TEST, GEOENGINEERING SOLUTION, INC. (2021) @
CONE PENETRATION TEST, GEOSPHERE
CONSULTANT, INC. (2014)
?!"
SOIL BORING, GEOSPHERE CONSULTANT,
INC. (2014)
SITE BOUNDARY
GEOLOGIC UNIT
ALLUVIUM, HOLOCENE (Qha)
ALLUVIUM, EARLY PLEISTOCENE, (Qoa)
NOTES
1. ALL LOCATIONS AND DIMENSIONS ARE APPROXIMATE.
2. GEOLOGIC UNIT SOURCE: UNITED STATE GEOLOGICL SURVEY
(USGS), 2022
3. ASSESSOR PARCEL DATA SOURCE: SAN MATEO COUNTY
4. AERIAL IMAGERY SOURCE: NEARMAP, 29 SEPTEMBER 2021
180 EL CAMINO REAL
SOUTH SAN FRANCISCO, CALIFORNIA)
SITE PLAN AND SITE GEOLOGY
FIGURE 4 SCALE: AS SHOWN
MARCH 2022
GIS FILE PATH: \\haleyaldrich\share\CF\Projects\0204226\GIS\Maps\2022_03\204226_SteelWave\204226_RESEARCH_AND_DEVELOPMENT_BUILDINGS_AND_PARKING_STRUCTURE.aprx ― USER: lphillips ― LAST SAVED: 3/30/2022 9:42 AM 0 150 300
SCALE IN FEET
10 FT
PRESSURE DUE TO
VEHICLE SURCHARGE
ALONG STREETS (HEAVY
EQUIPMENT SHOULD
COME NO CLOSER THAN 5
FEET TO FACE OF
EXCAVATION)
H = 11.5 TO 23.5 FT
PASSIVE
PRESSURE
240 pcf
1 GROUNDWATER
TABLE
(SEE NOTES
5 AND 6)
D
BOTTOM OF EXCAVATION
(APPROX. EL. 28.5 FEET)
BOTTOM OF
EXCAVATION
0.25H
60°
BOND LENGTH
(15-FT MIN.)
STRESSING LENGTH
(10-FT MIN. FOR BARS,
15-FT MIN. FOR STRANDS)
BOND BETWEEN ANCHOR
AND SOIL IS CONSIDERED
EFFECTIVE ONLY TO THE
RIGHT OF DASHED LINE
GROUND SURFACE
APPROXIMATE EL. = VARIES FROM 52
TO 40 FEET
H
TIEBACK
H1 NO LOAD ZONE
A + 32D
A
100 psf
2' 240 pcf
GROUND SURFACE
APPROXIMATE EL. = VARIES FROM 52
TO 40 FEET
0.2H
A
psf \\HALEYALDRICH.COM\SHARE\CF\PROJECTS\0203652\CAD\FIGURES\0203652_000_FIG 1_TEMP EARTH PRESS EXCV-REV1.DWG DTE FIG 1 5/10/2022 5:59 PM Sheet: Printed:
FIGURE 5
180 EL CAMINO REAL
SOUTH SAN FRANCISCO, CALIFORNIA
TEMPORARY LATERAL EARTH
PRESSURES FOR EXCAVATION
SCALE: NTS MAY 2022
NOTES
1. THESE SHORING PRESSURES ARE APPLICABLE TO SOLDIER BEAM AND LAGGING, WALLS WITHIN AN EXCAVATION HEIGHT OF UP TO 25 FEET.
2. PASSIVE PRESSURE DEPENDS ON DEPTH TO GROUNDWATER WITHIN EXCAVATION.
3. PASSIVE PRESSURE VALUES INCLUDE A FACTOR OF SAFETY OF 1.5.
4. ASSUMES SHORING WILL BE BRACED OR TIED BACK.
5. TO REDUCE THE POTENTIAL FOR A BLOWOUT, THE HYDRAULIC HEAD SHOULD BE LOWERED AT LEAST 3 FEET BELOW THE BOTTOM OF THE EXCAVATION (OR DEEPER IF REQUIRED FOR LATERAL STABILITY).
6. DESIGN GROUNDWATER AT EL. 20 FEET.
7. ALL DIMENSIONS IN FEET UNLESS NOTED OTHERWISE
8. IGNORE THE UPPER 2 FEET OF PASSIVE RESISTANCE.
9. USE AN TIEBACK ADHESION OF 1000 PSF. THIS VALUE INCLUDES A FACTOR OF SAFETY OF 1.5.
CONDITION A (psf)
ACTIVE 32H
AT-REST 48H
APPENDIX A
Boring Logs
IDENTIFICATION AND DESCRIPTION OF SUBSURFACE MATERIALS
SOIL
SUPPLEMENTAL SOIL TERMINOLOGY:
- 0 to 1/16 in. thick (cohesive)
- 0 to 1/16 in. thick (granular)
- 1/16 to 1/2 in. thick
- 1/2 to 12 in. thick
- > 12 in. thick
- Small, erratic deposit less than 12 in. size
- Lenticular deposit larger than a pocket
- One or less per 12 in. of thickness
- More than one per 12 in. of thickness
- Alternating soil layers of differing composition
- Alternating thin seams of silt and clay
- Variation of color
Laminae
Parting
Seam
Layer
Stratum
Pocket
Lens
Occasional
Frequent
Interbedded
Varved
Mottled
DENSITY OR CONSISTENCY
PENETRATION RESISTANCE
GEOLOGIC INTERPRETATION
Deposit type - GLACIAL TILL, ALLUVIUM, FILL.....
U.S. Standard Series Seive Clear Square Sieve Openings
UNIFIED SOIL CLASSIFICATION SYSTEM
TYPICAL NAMES
Well graded gravels, gravel-sand mixtures
Poorly graded gravels, gravel-sand mixtures
Well graded sands, gravelly sands
Poorly graded sands, gravelly sands
Silty sands, poorly graded sand-silt mixtures
Clayey sands, poorly graded sand-clay mixtures
Organic clays and organic silty clays of low plasticity Inorganic clays of high plasticity, fat clays
Peat and other highly organic soils
Inorganic silts and very fine sands, rock flour, silty or clayey fine sands or clayey silts with slight plasticity
Inorganic clays of low to medium plasticity, gravelly clays, sandy clays, silty clays, lean clays
Inorganic silty, micaceous or diatomaceous fine sandy or silty soils, elastic silts
Group
Symbol
Graphic
Symbol MAJOR DIVISIONS
Silty gravels, poorly graded gravel-sand-silt mixtures
Clayey gravels, poorly graded gravel-sand-clay mixtures Organic clays of medium to high plasticity, organic silts The natural soils are identified by criteria of Unified Soil Classification System (USCS), with appropriate group
symbol in parenthesis for each soil description.
Fill materials may not be classified by USCS criteria.
GENERAL NOTES
1. Logs of subsurface explorations depict soil, rock and groundwater conditions only at the locations specified on the dates indicated. Subsurface conditions may vary at other locations and at other times.
2. Water levels noted on the logs were measured at the times and under the conditions indicated. During test borings, these water levels could have been affected by the introduction of water into the borehole, extraction of tools on other procedures and thus may not reflect actual groundwater level at the test boring location. Groundwater level fluctuations may also occur as a result of variations in precipitation, temperature, season, tides, adjacent construction activities and pumping of water supply wells and construction dewatering systems.
Fine
Sand
Coarse Medium
Gravel
Coarse Fine
Boulders Cobbles
12" 3" 3/4" 4 10 40 200
Silts and Clays
305 mm 76 mm 19 mm 4.75 mm 2.00 mm 0.43 mm 0.074 mm
Gravels
More than half
of coarse
fraction is larger
than number 4
sieve
Gravels with
little or no fines
Gravels with
over 12% fines
Sands with little
or no fines
Sands with over
12% fines
Sands
More than half
of coarse
fraction is
smaller than
number 4 sieve
Coarse grained
soils:
more than half
is larger
than number
200 sieve
Fined-grained
soils:
more than half
smaller than
number 200
sieve
Silts and Clays
Liquid limit 50% or less
Silts and Clays
Liquid limit greater than 50%
Highly organic soils
GW
GP
GM
GC
SW
SP
SM
SC
ML
CL
OL
MH
CH
OH
PT
Soil description on logs of subsurface explorations are based on Standard Penetration Test results, visual-manual examination of exposed soil and soil samples, and the results of laboratory tests on selected samples. The criteria, descriptive terms and definitions are as follows:
Standard Penetration Test (ASTM D-1586) - Number of blows required to drive a standard 2 in. O.D. split spoon or a modified California sampler 1 ft., with a 140 lb. weight falling freely through 30 in.
Density of
Cohesionless Soils
Standard
Penetration
Test
(Blows per ft.)
Consistency of
Cohesive Soils
Penetration
Resistance
(Blows per ft.)
Very Loose
Loose
Medium Dense
Dense
Very Dense
0-4
5-10
11-30
31-50
> 50
Very Soft
Soft
Medium Stiff
Stiff
Very Stiff
Hard
0-2
3-4
5-8
9-15
16-30
> 30
COLOR: Color descriptions based on the Munsell Soil Color Chart Modified
California
(Blows per ft.)
0-4
5-12
13-35
36-60
> 60 MCELENEY, TERRI J:\GRAPHICS\TEMP\MCELENEY-T\FIELD SERVICES\SUBSURFACE EXPLORATION LOG KEY\HA-SUBSURFACE EXPLORATION KEY2018-0828 SOILS ONLY.DWG 8.5X11 P 8/28/2018 6:26 PM Layout: Printed:
GM
SM
ML
38.1 0.3
37.5 0.8
33.1 5.2
26.8 11.5
55 ASPHALT
Gray silty GRAVEL with sand (GM), no odor, dry (Fill)
Light-brown silty SAND (SM), no odor, moist
Very stiff to stiff olive-gray sandy SILT (ML), no structure, no odor, moist, low plasticity
BOTTOM OF EXPLORATION 11.5 FT
6 10
15 3
9 14
8 9
9 18
18 18 SPT MCS SPT
Client
Contractor PITCHER DRILLING SERVICES, INC
Project
STEELWAVE
180 EL CAMINO REAL, SOUTH SAN FRANCISCO
SPT - Standard Penetration Test
NGVD29
W. Vinaas
of 1
0204226-000
Plasticity : N - Nonplastic L - Low M - Medium H - High Dry Strength : N - None L - Low M - Medium H - High V - Very High Elevation
Sampler Type Legend
not encountered
of Casing
02/14/22 Samples
Cutting Head
PID Make & Model:
38.3 MCS - Modified California Sampler (2.43-in ID)
8.5 140
Hoist/Hammer:
Water
Bit Type:
See Plan
07:17
N. Vaiana
1 11.5
Boring No.
Time
Water Level Data
Note: Soil identification based on visual-manual methods of the USCS as practiced by Haley & Aldrich, Inc.
Sheet No.
Bottom Overburden (ft)
Finish
-3
14 February 2022
Boring Diameter (in.)
None
Winch/Automatic hammer
Start
File No.
HA-1
Rig Make & Model:
Dilatancy : R - Rapid S - Slow N - None
Toughness : L - Low M - Medium H - High
*Note: Maximum particle size (mps) is determined by direct observation within the limitations of sampler size.
Time (hr.)
Date
Hammer Fall (in.)
of Hole
Depth (ft) to:
Hammer Weight (lb)
Automatic hammer
MiniRAE 3000 10.6 eV
Casing:
HA-1
Drilling Equipment and Procedures
Datum
H&A Rep.
Hammer Type
Boring No.
Bottom
Elapsed
Summary
Field Tests:
Drill Mud:
Driller
30 CME 550
Location
Rock Cored (ft)
14 February 2022
GRAB - Grab Sample
Hallow Stem Auger
USCS Symbol Moisture (%) Stratum Change Elev/Depth (ft) Dry Density (pcf) Fines (%)
VISUAL-MANUAL IDENTIFICATION AND DESCRIPTION
(Density/consistency, color, GROUP NAME, max. particle size†, structure, odor, moisture, optional descriptions
GEOLOGIC INTERPRETATION)
GEOTECHNICAL TEST BORING REPORT
Elevation (ft) 35
30 25
Depth (ft)
0 5
10 15
H&A BORING MDH SAMPLE 0204226_PLOG-HA-LIB09.GLB PLOG-H&A.GDT \\HALEYALDRICH.COM\SHARE\CF\PROJECTS\0204226\000\GEO\GINT\0204226-000-TB-2.GPJ 8 Apr 22 Sampler Blows
per 6 in.
Sample Type
Recovery (in.)
Sample No. HA-1-1 HA-1-2 HA-1-3
GM
ML
CL
SC
SM
ML
SM
38.7 0.3 38.3
0.8 37.8
1.3 35.0
4.0 34.3
4.8 24.8
14.3 24.5
14.5 24.0
15.0 46
ASPHALT
Silty GRAVEL with sand (GM), moist (Fill)
Light-brown sandy SILT (ML), no odor (Fill), low plasticity Brown with red-brown lean CLAY with sand (CL), mottled, moist, medium plasticity At 2.0 ft, color change to light brown
Light-brown clayey SAND with gravel (SC), no odor, moist Medium dense to very dense light-brown silty SAND (SM), moist, medium to finegrained sand Stiff gray-brown sandy SILT (ML), no odor, moist
Medium dense gray-brown silty SAND (SM), moist
BOTTOM OF EXPLORATION 15.0 FT
14 19
26 7
10 12
7 14
19 2
9 18
18 12
18 18 SPT SPT MCS SPT
Client
Contractor PITCHER DRILLING SERVICES, INC
Project
STEELWAVE
180 EL CAMINO REAL, SOUTH SAN FRANCISCO
SPT - Standard Penetration Test
NGVD29
W. Vinaas
of 1
0204226-000
Plasticity : N - Nonplastic L - Low M - Medium H - High Dry Strength : N - None L - Low M - Medium H - High V - Very High Elevation
Sampler Type Legend
not encountered
of Casing
02/14/22 Samples
Cutting Head
PID Make & Model:
39.0 MCS - Modified California Sampler (2.43-in ID)
8.5 140
Hoist/Hammer:
Water
Bit Type:
See Plan
07:18
N. Vaiana
1 15
Boring No.
Time
Water Level Data
Note: Soil identification based on visual-manual methods of the USCS as practiced by Haley & Aldrich, Inc.
Sheet No.
Bottom Overburden (ft)
Finish
-4
14 February 2022
Boring Diameter (in.)
None
Winch/Automatic hammer
Start
File No.
HA-2
Rig Make & Model:
Dilatancy : R - Rapid S - Slow N - None
Toughness : L - Low M - Medium H - High
*Note: Maximum particle size (mps) is determined by direct observation within the limitations of sampler size.
Time (hr.)
Date
Hammer Fall (in.)
of Hole
Depth (ft) to:
Hammer Weight (lb)
Automatic hammer
MiniRAE 3000 10.6 eV
Casing:
HA-2
Drilling Equipment and Procedures
Datum
H&A Rep.
Hammer Type
Boring No.
Bottom
Elapsed
Summary
Field Tests:
Drill Mud:
Driller
30 CME 550
Location
Rock Cored (ft)
14 February 2022
GRAB - Grab Sample
Hallow Stem Auger
USCS Symbol Moisture (%) Stratum Change Elev/Depth (ft) Dry Density (pcf) Fines (%)
VISUAL-MANUAL IDENTIFICATION AND DESCRIPTION
(Density/consistency, color, GROUP NAME, max. particle size†, structure, odor, moisture, optional descriptions
GEOLOGIC INTERPRETATION)
GEOTECHNICAL TEST BORING REPORT
Elevation (ft) 35
30 25
Depth (ft)
0 5
10 15
H&A BORING MDH SAMPLE 0204226_PLOG-HA-LIB09.GLB PLOG-H&A.GDT \\HALEYALDRICH.COM\SHARE\CF\PROJECTS\0204226\000\GEO\GINT\0204226-000-TB-2.GPJ 8 Apr 22 Sampler Blows
per 6 in.
Sample Type
Recovery (in.)
Sample No. HA-2-1 HA-2-2 HA-2-3 HA-2-4
SC
SP-SM
SM
ML
SM
SM
33.8 0.3
30.0 4.0
29.0 5.0
28.5 5.5
28.0 6.0
25.8 8.3
22.5 11.5
35 ASPHALT
Light-brown clayey SAND (SC), no odor, moist
Light-brown with red-brown poorly-graded SAND with silt (SP-SM), moist Medium dense to medium dense brown silty SAND (SM), moist Olive-brown to light-brown sandy SILT (ML), moist, low plasticity Medium dense brown to red-brown silty SAND (SM), no odor, moist, medium-grained sand
Medium dense light-brown to olive silty SAND (SM), no odor, moist, medium to finegrained sand BOTTOM OF EXPLORATION 11.5 FT
4 12
15 6
9 14
3 10
14 18
18 18 SPT SPT SPT
Client
Contractor PITCHER DRILLING SERVICES, INC
Project
STEELWAVE
180 EL CAMINO REAL, SOUTH SAN FRANCISCO
SPT - Standard Penetration Test
NGVD29
W. Vinaas
of 1
0204226-000
Plasticity : N - Nonplastic L - Low M - Medium H - High Dry Strength : N - None L - Low M - Medium H - High V - Very High Elevation
Sampler Type Legend
not encountered
of Casing
02/14/22 Samples
Cutting Head
PID Make & Model:
34.0 MCS - Modified California Sampler (2.43-in ID)
8.5 140
Hoist/Hammer:
Water
Bit Type:
See Plan
07:18
N. Vaiana
1 11.5
Boring No.
Time
Water Level Data
Note: Soil identification based on visual-manual methods of the USCS as practiced by Haley & Aldrich, Inc.
Sheet No.
Bottom Overburden (ft)
Finish
-3
14 February 2022
Boring Diameter (in.)
None
Winch/Automatic hammer
Start
File No.
HA-3
Rig Make & Model:
Dilatancy : R - Rapid S - Slow N - None
Toughness : L - Low M - Medium H - High
*Note: Maximum particle size (mps) is determined by direct observation within the limitations of sampler size.
Time (hr.)
Date
Hammer Fall (in.)
of Hole
Depth (ft) to:
Hammer Weight (lb)
Automatic hammer
MiniRAE 3000 10.6 eV
Casing:
HA-3
Drilling Equipment and Procedures
Datum
H&A Rep.
Hammer Type
Boring No.
Bottom
Elapsed
Summary
Field Tests:
Drill Mud:
Driller
30 CME 550
Location
Rock Cored (ft)
14 February 2022
GRAB - Grab Sample
Hallow Stem Auger
USCS Symbol Moisture (%) Stratum Change Elev/Depth (ft) Dry Density (pcf) Fines (%)
VISUAL-MANUAL IDENTIFICATION AND DESCRIPTION
(Density/consistency, color, GROUP NAME, max. particle size†, structure, odor, moisture, optional descriptions
GEOLOGIC INTERPRETATION)
GEOTECHNICAL TEST BORING REPORT
Elevation (ft) 30
25 20
Depth (ft)
0 5
10 15
H&A BORING MDH SAMPLE 0204226_PLOG-HA-LIB09.GLB PLOG-H&A.GDT \\HALEYALDRICH.COM\SHARE\CF\PROJECTS\0204226\000\GEO\GINT\0204226-000-TB-2.GPJ 8 Apr 22 Sampler Blows
per 6 in.
Sample Type
Recovery (in.)
Sample No. HA-3-1 HA-3-2 HA-3-3
SC
CL
CL
SC
CL
CL
32.8 0.3
31.1 2.0
29.8 3.3
28.6 4.5
28.1 5.0
27.9 5.3
26.1 7.0
26.0 7.1
ASPHALT
Olive-brown to clayey SAND (SC), no odor, moist (Fill)
Gray sandy lean CLAY (CL), no odor, moist (Fill), medium plasticity Gray-brown to dark brown sandy lean CLAY with gravel (CL), moist (Fill), medium plasticity
Gray clayey SAND with gravel (SC), no odor, moist (Fill) Stiff light-brown sandy lean CLAY (CL), no odor, moist (Fill), medium plasticity LL=31, PI=15
Stiff gray with dark brown sandy lean CLAY (CL), bedded, no odor, moist (Fill), medium plasticity
CONCRETE
BOTTOM OF EXPLORATION 7.1 FT
5 9
13 10/1.2"
18 1 GRAB MCS SPT
Client
Contractor PITCHER DRILLING SERVICES, INC
Project
STEELWAVE
180 EL CAMINO REAL, SOUTH SAN FRANCISCO
SPT - Standard Penetration Test
NGVD29
W. Vinaas
of 1
0204226-000
Plasticity : N - Nonplastic L - Low M - Medium H - High Dry Strength : N - None L - Low M - Medium H - High V - Very High Elevation
Sampler Type Legend
not encountered
of Casing
02/14/22 Samples
Cutting Head
PID Make & Model:
33.1 MCS - Modified California Sampler (2.43-in ID)
8.5 140
Hoist/Hammer:
Water
Bit Type:
See Plan
07:18
N. Vaiana
1 7.1
Boring No.
Time
Water Level Data
Note: Soil identification based on visual-manual methods of the USCS as practiced by Haley & Aldrich, Inc.
Sheet No.
Bottom Overburden (ft)
Finish
-3
14 February 2022
Boring Diameter (in.)
None
Winch/Automatic hammer
Start
File No.
HA-4
Rig Make & Model:
Dilatancy : R - Rapid S - Slow N - None
Toughness : L - Low M - Medium H - High
*Note: Maximum particle size (mps) is determined by direct observation within the limitations of sampler size.
Time (hr.)
Date
Hammer Fall (in.)
of Hole
Depth (ft) to:
Hammer Weight (lb)
Automatic hammer
MiniRAE 3000 10.6 eV
Casing:
HA-4
Drilling Equipment and Procedures
Datum
H&A Rep.
Hammer Type
Boring No.
Bottom
Elapsed
Summary
Field Tests:
Drill Mud:
Driller
30 CME 550
Location
Rock Cored (ft)
14 February 2022
GRAB - Grab Sample
Hallow Stem Auger
USCS Symbol Moisture (%) Stratum Change Elev/Depth (ft) Dry Density (pcf) Fines (%)
VISUAL-MANUAL IDENTIFICATION AND DESCRIPTION
(Density/consistency, color, GROUP NAME, max. particle size†, structure, odor, moisture, optional descriptions
GEOLOGIC INTERPRETATION)
GEOTECHNICAL TEST BORING REPORT
Elevation (ft) 30
25 20
Depth (ft)
0 5
10 15
H&A BORING MDH SAMPLE 0204226_PLOG-HA-LIB09.GLB PLOG-H&A.GDT \\HALEYALDRICH.COM\SHARE\CF\PROJECTS\0204226\000\GEO\GINT\0204226-000-TB-2.GPJ 8 Apr 22 Sampler Blows
per 6 in.
Sample Type
Recovery (in.)
Sample No. HA-4-C HA-4-1 HA-4-2
GM
CL
SM
SC
CL
SM
SM
32.3 0.3
31.7 0.8
30.0 2.5
29.0 3.5
25.5 7.0
22.3 10.3
19.5 13.0
17.5 15.0
30 ASPHALT
Gray-brown silty GRAVEL with sand (GM), no odor, moist (Fill) Olive-gray sandy lean CLAY (CL), no odor, moist, 5% (Fill), medium plasticity Dark brown silty SAND with gravel (SM), no odor, dry (Fill) Medium dense light-brown to olive-gray clayey SAND with gravel (SC), no odor, moist (Fill)
At 5.0 ft, color change to dark greenish gray
Stiff dark brown sandy lean CLAY (CL), no odor, moist (Fill), medium plasticity Medium dense dark brown with gray silty SAND with gravel (SM), no odor, moist, 15% construction debris (Fill)
Loose gray-brown silty SAND (SM), no odor, moist to wet BOTTOM OF EXPLORATION 15.0 FT
8 12
15 4
5 11
7 11
9 1
3 5
18 18
18 18 MCS SPT MCS SPT
Client
Contractor PITCHER DRILLING SERVICES, INC
Project
STEELWAVE
180 EL CAMINO REAL, SOUTH SAN FRANCISCO
SPT - Standard Penetration Test
NGVD29
W. Vinaas
of 1
0204226-000
Plasticity : N - Nonplastic L - Low M - Medium H - High Dry Strength : N - None L - Low M - Medium H - High V - Very High Elevation
Sampler Type Legend
not encountered
of Casing
02/15/22 Samples
Cutting Head
PID Make & Model:
32.5 MCS - Modified California Sampler (2.43-in ID)
8.5 140
Hoist/Hammer:
Water
Bit Type:
See Plan
07:18
N. Vaiana
1 15
Boring No.
Time
Water Level Data
Note: Soil identification based on visual-manual methods of the USCS as practiced by Haley & Aldrich, Inc.
Sheet No.
Bottom Overburden (ft)
Finish
-4
14 February 2022
Boring Diameter (in.)
None
Winch/Automatic hammer
Start
File No.
HA-5
Rig Make & Model:
Dilatancy : R - Rapid S - Slow N - None
Toughness : L - Low M - Medium H - High
*Note: Maximum particle size (mps) is determined by direct observation within the limitations of sampler size.
Time (hr.)
Date
Hammer Fall (in.)
of Hole
Depth (ft) to:
Hammer Weight (lb)
Automatic hammer
MiniRAE 3000 10.6 eV
Casing:
HA-5
Drilling Equipment and Procedures
Datum
H&A Rep.
Hammer Type
Boring No.
Bottom
Elapsed
Summary
Field Tests:
Drill Mud:
Driller
30 CME 550
Location
Rock Cored (ft)
14 February 2022
GRAB - Grab Sample
Hallow Stem Auger
USCS Symbol Moisture (%) Stratum Change Elev/Depth (ft) Dry Density (pcf) Fines (%)
VISUAL-MANUAL IDENTIFICATION AND DESCRIPTION
(Density/consistency, color, GROUP NAME, max. particle size†, structure, odor, moisture, optional descriptions
GEOLOGIC INTERPRETATION)
GEOTECHNICAL TEST BORING REPORT
Elevation (ft) 30
25 20
Depth (ft)
0 5
10 15
H&A BORING MDH SAMPLE 0204226_PLOG-HA-LIB09.GLB PLOG-H&A.GDT \\HALEYALDRICH.COM\SHARE\CF\PROJECTS\0204226\000\GEO\GINT\0204226-000-TB-2.GPJ 8 Apr 22 Sampler Blows
per 6 in.
Sample Type
Recovery (in.)
Sample No. HA-5-1 HA-5-2 HA-5-3 HA-5-4
GM
SM
CL
SM
SP-SM
SM
SP-SM
SM
28.8 0.3
28.2 0.8
26.5 2.5
24.3 4.8
23.3 5.8
22.0 7.0
19.5 9.5
16.5 12.5
11.5 17.5
ASPHALT
Gray-brown silty GRAVEL with sand (GM) (Fill)
Light-brown silty SAND (SM), moist (Fill)
Brown lean CLAY with sand (CL), heterogeneous, no odor, moist (Fill), medium plasticity
Dense brown silty SAND (SM), no odor, moist
Dense brown poorly-graded SAND with silt and gravel (SP-SM), moist Loose dark brown to gray silty SAND (SM), hydrocarbon odor, moist Medium dense gray poorly-graded SAND with silt (SP-SM), homogeneous, hydrocarbon odor, moist, medium-grained sand
Loose to medium dense gray silty SAND (SM), homogeneous, hydrocarbon odor, moist, medium to fine-grained sand
BOTTOM OF EXPLORATION 17.5 FT
11 16
17 1
2 3
2 4
7 1
4 5
6 4
8 18
18 18
18 18 GRAB MCS SPT SPT SPT SPT
Client
Contractor PITCHER DRILLING SERVICES, INC
Project
STEELWAVE
180 EL CAMINO REAL, SOUTH SAN FRANCISCO
SPT - Standard Penetration Test
NGVD29
W. Vinaas
of 1
0204226-000
Plasticity : N - Nonplastic L - Low M - Medium H - High Dry Strength : N - None L - Low M - Medium H - High V - Very High Elevation
Sampler Type Legend
not encountered
of Casing
02/14/22 Samples
Cutting Head
PID Make & Model:
29.0 MCS - Modified California Sampler (2.43-in ID)
8.5 140
Hoist/Hammer:
Water
Bit Type:
See Plan
07:18
N. Vaiana
1 17.5
Boring No.
Time
Water Level Data
Note: Soil identification based on visual-manual methods of the USCS as practiced by Haley & Aldrich, Inc.
Sheet No.
Bottom Overburden (ft)
Finish
-5
14 February 2022
Boring Diameter (in.)
None
Winch/Automatic hammer
Start
File No.
HA-6
Rig Make & Model:
Dilatancy : R - Rapid S - Slow N - None
Toughness : L - Low M - Medium H - High
*Note: Maximum particle size (mps) is determined by direct observation within the limitations of sampler size.
Time (hr.)
Date
Hammer Fall (in.)
of Hole
Depth (ft) to:
Hammer Weight (lb)
Automatic hammer
MiniRAE 3000 10.6 eV
Casing:
HA-6
Drilling Equipment and Procedures
Datum
H&A Rep.
Hammer Type
Boring No.
Bottom
Elapsed
Summary
Field Tests:
Drill Mud:
Driller
30 CME 550
Location
Rock Cored (ft)
14 February 2022
GRAB - Grab Sample
Hallow Stem Auger
USCS Symbol Moisture (%) Stratum Change Elev/Depth (ft) Dry Density (pcf) Fines (%)
VISUAL-MANUAL IDENTIFICATION AND DESCRIPTION
(Density/consistency, color, GROUP NAME, max. particle size†, structure, odor, moisture, optional descriptions
GEOLOGIC INTERPRETATION)
GEOTECHNICAL TEST BORING REPORT
Elevation (ft) 25
20 15
10 Depth (ft)
0 5
10 15
H&A BORING MDH SAMPLE 0204226_PLOG-HA-LIB09.GLB PLOG-H&A.GDT \\HALEYALDRICH.COM\SHARE\CF\PROJECTS\0204226\000\GEO\GINT\0204226-000-TB-2.GPJ 8 Apr 22 Sampler Blows
per 6 in.
Sample Type
Recovery (in.)
Sample No. HA-6-C HA-6-1 HA-6-2 HA-6-3 HA-6-4 HA-6-5
APPENDIX B
Cone Penetration Test Results
Haley & Aldrich, Inc.
Project 180 El Camino Real Operator BH-GM Filename SDF(498).cptJob Number 0204226 Cone Number DDG1587 GPSHole Number CPT-01 Date and Time 2/14/2022 2:42:25 PM Maximum Depth 79.89 ftEST GW Depth During Test 18.21 ft Net Area Ratio .8Cone Size 15cm squared Soil Behavior Referance *Soil behavior type and SPT based on data from UBC-1983 0 10 20 30 40 50 60 70 80
0 600
TIP
TSF 0 12
FRICTION
TSF 0 10
Fs/Qt
% -50 300
PRESSURE U2
PSI 0 12
1 - sensitive fine grained 2 - organic material 3 - clay 4 - silty clay to clay 5 - clayey silt to silty clay 6 - sandy silt to clayey silt 7 - silty sand to sandy silt 8 - sand to silty sand 9 - sand 10 - gravelly sand to sand 11 - very stiff fine grained (*)12 - sand to clayey sand (*)
CPT DATA
DEPTH
(ft)
SOIL
BEHAVIOR
TYPE
Haley & Aldrich, Inc.
Location 180 El Camino Real Operator BH-GMJob Number 0204226 Cone Number DDG1587 GPSHole Number CPT-01 Date and Time 2/14/2022 2:42:25 PMEquilized Pressure 4.1 EST GW Depth During Test 18.2
27.89 ft
0 0 Time (Sec) 350.00
5 -4
PRESSURE U2 PSI
APPENDIX C
Infiltration Test Results
File No.: 204226
Sheet: 1 of 2
Client: Steelwave Date: 2/14/2022
Project: 180 El Camino Field Rep. NV
Subject: Boring/Excavation Percolation Testing Field Log HA-1 64 inches
8.5 inches 5.00 feet
2 inches 8 inches
Reading
Number
Time
Start/End
Elapsed
Time
Final
Water
Depth
Water
Drop
Direct
Percolation
Rate
Reduction
Factor
Adjusted
Percolation
Rate
(min) (in) (in) (in/hr) (in/hr)
10:30
11:00
11:00
11:30
11:30
12:10
12:10
12:40
12:40
13:10
13:10
13:40
13:40
14:10
Average of Last 3 Readings: 9.25 13.63 0.68
Reduction Factors
Rf = 13.63 (Calculated as Rf = [(2d1 - ∆d) / DIA] + 1)
CFv = 1.5 (moderate site variability, low number of tests) CFs = 2 (moderate long-term siltation)
CFtotal = 40.9 (product of Rf, CFv, and CFs)
Design Percolation Rate
Unadjusted Percolation Rate (PR) = 9.25 in/hour (average of last three) Design Percolation Rate (PR / Cftotal) = 0.23 in/hour
( 1.6E-04 cm/s )
\\haleyaldrich.com\share\CF\Projects\0204226\000\Geo\Project_Data\Field_Data\Infiltration\[0204226-000_Boring_Perc_Spreadsheet_2022.xlsx]PERC-1 7 30 12.50 4.50 9.00 13.65 0.66
0.74 6 30 12.75 4.75 9.50 13.62 0.70
5 30 13.00 5.00 10.00 13.59
0.67 4 30 12.50 4.50 9.00 13.65 0.66
3 40 14.00 6.00 9.00 13.47
0.97 2 30 13.00 5.00 10.00 13.59 0.74
1 30 14.50 6.50 13.00 13.41
Boring/Test Number
Diameter of Boring
Diameter of Casing
PERCOLATION TEST DATA
Length of Casing
Depth of Casing Below
Depth to Initial Water
File No.: 204226
Sheet: 2 of 2
Client: Steelwave Date: 2/14/2022
Project: 180 El Camino Field Rep. NV
Subject: Boring/Excavation Percolation Testing Field Log HA-2 64 inches
8.5 inches 5.00 feet
2 inches 9 inches
Reading
Number
Time
Start/End
Elapsed
Time
Final
Water
Depth
Water
Drop
Direct
Percolation
Rate
Reduction
Factor
Adjusted
Percolation
Rate
(min) (in) (in) (in/hr) (in/hr)
12:37
13:07
13:07
13:37
13:37
14:07
14:07
14:37
14:37
15:07
15:07
15:37
15:37
16:07
Average of Last 3 Readings: 1.00 13.88 0.07
Reduction Factors
Rf = 13.88 (Calculated as Rf = [(2d1 - ∆d) / DIA] + 1)
CFv = 1.5 (moderate site variability, low number of tests) CFs = 2 (moderate long-term siltation)
CFtotal = 41.6 (product of Rf, CFv, and CFs)
Design Percolation Rate
Unadjusted Percolation Rate (PR) = 1.00 in/hour (average of last three) Design Percolation Rate (PR / Cftotal) = 0.02 in/hour
( 1.4E-05 cm/s )
\\haleyaldrich.com\share\CF\Projects\0204226\000\Geo\Project_Data\Field_Data\Infiltration\[0204226-000_Boring_Perc_Spreadsheet_2022.xlsx]PERC-1 7 30 9.50 0.50 1.00 13.88 0.07
0.07 6 30 9.50 0.50 1.00 13.88 0.07
5 30 9.50 0.50 1.00 13.88
0.07 4 30 9.50 0.50 1.00 13.88 0.07
3 30 9.50 0.50 1.00 13.88
0.03 2 30 9.50 0.50 1.00 13.88 0.07
1 30 9.20 0.20 0.40 13.92
Boring/Test Number
Diameter of Boring
Diameter of Casing
PERCOLATION TEST DATA
Length of Casing
Depth of Casing Below
Depth to Initial Water
APPENDIX D
Previous Boring Logs and Cone Penetration Test Results
Summary Table of Boring Log by Others
Boring Designation Date Drilled Depth Interval
(feet) Soil Description Pertinent Test Results
0-2 LEAN CLAY (CL), light brown and gray,
stiff, moist, with fine sand (Fill)
LL=26, PI=9;
PP=1.0 ksf Undrained SS;
DD=100 pcf, MC=20%
2-4.5 CLAYEY SAND (SC), brown, medium
dense, moist, fine to medium sand (Fill) DD=121 pcf, MC=13%
4.5-8.5 SAND (SP-SM), light brown, medium
dense, fine to medium sand DD=101 pcf, MC=8%
8.5-13.5 SANDY SILT(ML), light brown, stiff,
moist
% Passing #200 = 50%
MC=24%
13.5-17.5 SILTY SAND (SM), dark grayish brown to
gray, loose to medium dense, moist
17.5-19
SAND with SILT (SP-SM), BROWN,
medium dense, moist, fine to medium
sand
MC=23%
19-21.5
SILTY SAND (SM), grayish brown,
medium dense to loose, moist, some
rootlets & clay
21.5-28
FAT CLAY (CH), dark gray, very stiff,
moist, some fine sand, moderate to
high plasticity
DD=88 pcf, MC=27%
PP=3.0 ksf Undrained SS
28-43 SILTY SAND (SM), gray, medium dense
to dense, moist, some organics
% Passing #200 = 31%
@31', 10%@36'
43-45.5 LEAN CLAY WITH SAND (CL), olive gray,
very stiff, moist
LB-1
(GW encountered
during drilling at 30')
10/29/2004
KEY TO EXPLORATORY BORING LOGS
110
PLASTICITY CHART
LIQUID LIMITS (%)
PLASTICITY INDEX (%)
"A" LINE
CL-ML
CL-OL
CH-OH
OL-ML
OH-MH
0-30
(Low)
30-50
(Medium)
>50
(High)
50 60
40 30
20 10
0 0 10 20 30 40 50 60 8070 90 100
Grab Bulk Sample Initial Water Level Reading
Shelby Tube
Standard Penetration Test
2.5 Inch Modified California
Final Water Level Reading
No Recovery
Blow Count
The number of blows of the sampling hammer required
to drive the sampler through each of three 6-inch
increments. Less than three increments may be reported
if more than 50 blows are counted for any increment.
The notation 50/5” indicates 50 blows recorded for 5
inches of penetration.
N-Value
Number of blows 140 LB hammer falling 30 inches
to drive a 2 inch outside diameter (1-3/8 inch I.D)
split barrel sampler the last 12 inches of an 18
inch drive (ASTM-1586 Standard Penetration Test)
CU -
DS - Results of Direct Shear test in terms of total cohesion (C, KSF) or effective cohesion and friction angles (C’, KSF and degrees)
LL - Liquid Limit
PI - Plasticity Index
PP - Pocket Penetrometer test
TV - Torvane Shear Test results in terms of undrained shear strength (KSF) UC - Unconfined Compression test results in terms of undrained shear strength (KSF) #200 - Percent passing number 200 sieve
Cu - Coefficient of Uniformity
Cc - Coefficient of Concavity
Consolidated Undrained triaxial test completed. Refer to laboratory results General Notes
1. The boring locations were determined by pacing, sighting and/or measuring from site features. Locations are approximate. Elevations of borings (if included) were determined by interpolation between plan contours or from another source that will be identified in the report or on the project site plan. The location and elevation of borings should be considered accurate only to the degree implied by the method used.
2. The stratification lines represent the approximate boundary between soil types. The transition may be gradual.
3. Water level readings in the drill holes were recorded at time and under conditions stated on the boring logs. This data has been reviewed and interpretations have been made in the text of this report. However, it must be noted that fluctuations in the level of the groundwater may occur due to variations in rainfall, tides, temperature and other factors at the time measurements were made.
4. The boring logs and attached data should only be used in accordance with the report.
MC
1-1
MC
1-2
MC
1-3
SPT
1-4
SPT
1-5
MC
1-6
106
111
18 17
9 25
2.5" ASPHALT PAVEMENT
7" AGGREGATE BASE
(CL) SANDY CLAY : Bluish-gray, moist, stiff
(SM) SILTY SAND : Yellowish-brown, w/ dark brown fine sand inclusions, moist, medium dense
Very dark greenish-gray, slightly foul odor and slightly plastic (GW) SANDY GRAVEL : Black, fine, moist, w/ trace organics, very dense, gravel is fractured & angular
(SM) SILTY SAND : Gray, moist, w/ trace clay, very fine-grained, medium dense
Dark gray, moist, stratum composed of small interchanging layers of sandy silt and fine silty sand, stiff
(CL-ML) SILTY CLAY : Dark black, moist, slight odor, stiff 3-5-8
(13)
3-5-7
(12)
25-13-39
(52)
4-5-6
(11)
7-5-6
(11)
3-5-8
(13) 1.3
NOTES
GROUND ELEVATION 31.3 ft
LOGGED BY DE
DRILLING METHOD Mobile B-53
HOLE SIZE 8"
DRILLING CONTRACTOR Exploration Geoservices Inc. GROUND WATER LEVELS:
CHECKED BY CTD
DATE STARTED 9/9/14 COMPLETED 9/9/14
AT TIME OF DRILLING 35.00 ft / Elev -3.70 ft
AT END OF DRILLING 32.00 ft / Elev -0.70 ft
AFTER DRILLING --- SAMPLE TYPE NUMBER RECOVERY % (RQD)
DRY UNIT WT.
(pcf)
MOISTURE
CONTENT (%)
LIQUID
LIMIT
PLASTIC
LIMIT
PLASTICITY
INDEX
FINES CONTENT
(%)
ATTERBERG
LIMITS
(Continued Next Page)
PLASTICITY
INDEX
GRAPHIC
LOG
DEPTH
(ft)
0 5
10 15
20 25
MATERIAL DESCRIPTION
SPT BLOW
COUNTS
(N VALUE)
POCKET PEN.
(tsf)
PAGE 1 OF 2
BORING NUMBER B-1
PROJECT NUMBER 91-03317-A
PROJECT NAME Centennial Village
PROJECT LOCATION 180 El Camino Real, South San Francisco CLIENT The W. T. Mitchell Group
2001 Crow Canyon Road, Suite 210
San Ramon, CA 94583
Telephone: (925) 314-7100
Fax: (925) 314-7180
MC
1-7
SPT
1-8
(CL-ML) SILTY CLAY : Dark black, moist, slight odor, stiff (continued)
(CH) FAT CLAY : Dark black, medium to high plasticity, moist, stiff (SC) CLAYEY SAND : Dark gray, wet, fine-grained, dense
Bottom of borehole at 35.0 feet.
3-4-5
(9)
5-17-15
(32)
0.75 SAMPLE TYPE
NUMBER
RECOVERY %
(RQD)
DRY UNIT WT.
(pcf)
MOISTURE
CONTENT (%)
LIQUID
LIMIT
PLASTIC
LIMIT
PLASTICITY
INDEX
FINES CONTENT
(%)
ATTERBERG
LIMITS
PLASTICITY
INDEX
GRAPHIC
LOG
DEPTH
(ft)
25 30
35 MATERIAL DESCRIPTION
SPT BLOW
COUNTS
(N VALUE)
POCKET PEN.
(tsf)
PAGE 2 OF 2
BORING NUMBER B-1
PROJECT NUMBER 91-03317-A
PROJECT NAME Centennial Village
PROJECT LOCATION 180 El Camino Real, South San Francisco CLIENT The W. T. Mitchell Group
2001 Crow Canyon Road, Suite 210
San Ramon, CA 94583
Telephone: (925) 314-7100
Fax: (925) 314-7180
MC
2-1
MC
2-2
MC
2-3
SPT
2-4
SPT
2-5
SPT
2-6
105
119
109
8 9
19 26
36 3.5" ASPHALT PAVEMENT
9" AGGREGATE BASE
(SM) SILTY SAND : Light yellowish-brown, moist, cemented, very dense
(SC) CLAYEY SAND : Mottled dark brown and reddish-brown, damp to moist, slightly cemented, dense, w/ silt
Changes to dark black color
(SM) SILTY SAND : Dark greenish-gray, very moist, medium dense
(ML) SANDY SILT : Dark brown, moist, w/ clay, medium dense (SM) SILTY SAND : Dark greenish gray, moist, w/ trace clay, medium dense
(SM) SANDY SILT : Black, very moist, fine grained, slightly plastic, medium dense
11-30-33
(63)
10-16-22
(38)
3-6-8
(14)
4-5-6
(11)
6-4-4
(8)
4-5-7
(12)
>4.5
2.0 NOTES
GROUND ELEVATION 36.5 ft
LOGGED BY DE
DRILLING METHOD Mobile B-53
HOLE SIZE 8"
DRILLING CONTRACTOR Exploration Geoservices Inc. GROUND WATER LEVELS:
CHECKED BY CTD
DATE STARTED 9/9/14 COMPLETED 9/9/14
AT TIME OF DRILLING 34.00 ft / Elev 2.50 ft
AT END OF DRILLING 36.00 ft / Elev 0.50 ft
AFTER DRILLING --- SAMPLE TYPE NUMBER RECOVERY % (RQD)
DRY UNIT WT.
(pcf)
MOISTURE
CONTENT (%)
LIQUID
LIMIT
PLASTIC
LIMIT
PLASTICITY
INDEX
FINES CONTENT
(%)
ATTERBERG
LIMITS
(Continued Next Page)
PLASTICITY
INDEX
GRAPHIC
LOG
DEPTH
(ft)
0 5
10 15
20 25
MATERIAL DESCRIPTION
SPT BLOW
COUNTS
(N VALUE)
POCKET PEN.
(tsf)
PAGE 1 OF 2
BORING NUMBER B-2
PROJECT NUMBER 91-03317-A
PROJECT NAME Centennial Village
PROJECT LOCATION 180 El Camino Real, South San Francisco CLIENT The W. T. Mitchell Group
2001 Crow Canyon Road, Suite 210
San Ramon, CA 94583
Telephone: (925) 314-7100
Fax: (925) 314-7180
SPT
2-7
SPT
2-8
SPT
2-9
19 (SM) SANDY SILT : Black, very moist, fine grained, slightly plastic, medium dense (continued)
(SM) CLAYEY SILTY SAND : Bluish-gray, very moist, medium dense
Becomes wet, dense
No water on sampler, water is perched above, becomes medium dense
Bottom of borehole at 40.0 feet.
5-10-14
(24)
16-15-22
(37)
10-9-10
(19)
SAMPLE TYPE
NUMBER
RECOVERY %
(RQD)
DRY UNIT WT.
(pcf)
MOISTURE
CONTENT (%)
LIQUID
LIMIT
PLASTIC
LIMIT
PLASTICITY
INDEX
FINES CONTENT
(%)
ATTERBERG
LIMITS
PLASTICITY
INDEX
GRAPHIC
LOG
DEPTH
(ft)
25 30
35 40
MATERIAL DESCRIPTION
SPT BLOW
COUNTS
(N VALUE)
POCKET PEN.
(tsf)
PAGE 2 OF 2
BORING NUMBER B-2
PROJECT NUMBER 91-03317-A
PROJECT NAME Centennial Village
PROJECT LOCATION 180 El Camino Real, South San Francisco CLIENT The W. T. Mitchell Group
2001 Crow Canyon Road, Suite 210
San Ramon, CA 94583
Telephone: (925) 314-7100
Fax: (925) 314-7180
MC
3-1
MC
3-2
MC
3-3
MC
3-4
MC
3-5
SPT
3-6
104
122
3 9
55 5" ASPHALT PAVEMENT
6" AGGREGATE BASE
(SP) SAND : Brown, fine to medium coarse, moist, w/ silt, loose [Fill?]
(GW) CLAYEY SAND w/ GRAVEL grades to GRAVEL w/ SAND :
Mottled reddish-brown and dark-brown, medium dense
[FILL?]
(CL) LEAN CLAY : Mottled yellowish-brown & black, moist to very moist, medium stiff
(ML) SANDY SILT : Dark gray, moist, odor, medium dense, fine-grained
(CL-ML) SILTY CLAY : Dark black, moist, stiff
(CL) SANDY CLAY : Greenish-gray, moist, stiff
3-4-4
(8)
3-8-7
(15)
2-3-3
(6)
3-5-5
(10)
2-3-5
(8)
4-5-6
(11)
0.50 NOTES
GROUND ELEVATION 39.1 ft
LOGGED BY DE
DRILLING METHOD Mobile B-53
HOLE SIZE 8"
DRILLING CONTRACTOR Exploration Geoservices Inc. GROUND WATER LEVELS:
CHECKED BY CTD
DATE STARTED 9/9/14 COMPLETED 9/9/14
AT TIME OF DRILLING --- AT END OF DRILLING --- No Groundwater Encountered.
AFTER DRILLING --- SAMPLE TYPE NUMBER RECOVERY % (RQD)
DRY UNIT WT.
(pcf)
MOISTURE
CONTENT (%)
LIQUID
LIMIT
PLASTIC
LIMIT
PLASTICITY
INDEX
FINES CONTENT
(%)
ATTERBERG
LIMITS
(Continued Next Page)
PLASTICITY
INDEX
GRAPHIC
LOG
DEPTH
(ft)
0 5
10 15
20 25
MATERIAL DESCRIPTION
SPT BLOW
COUNTS
(N VALUE)
POCKET PEN.
(tsf)
PAGE 1 OF 2
BORING NUMBER B-3
PROJECT NUMBER 91-03317-A
PROJECT NAME Centennial Village
PROJECT LOCATION 180 El Camino Real, South San Francisco CLIENT The W. T. Mitchell Group
2001 Crow Canyon Road, Suite 210
San Ramon, CA 94583
Telephone: (925) 314-7100
Fax: (925) 314-7180
SPT
3-7
SPT
3-8
(ML) CLAYEY SILT : Greenish-gray, very moist, stiff, w/ sand Bottom of borehole at 35.0 feet.
3-4-5
(9)
3-4-6
(10)
SAMPLE TYPE
NUMBER
RECOVERY %
(RQD)
DRY UNIT WT.
(pcf)
MOISTURE
CONTENT (%)
LIQUID
LIMIT
PLASTIC
LIMIT
PLASTICITY
INDEX
FINES CONTENT
(%)
ATTERBERG
LIMITS
PLASTICITY
INDEX
GRAPHIC
LOG
DEPTH
(ft)
25 30
35 MATERIAL DESCRIPTION
SPT BLOW
COUNTS
(N VALUE)
POCKET PEN.
(tsf)
PAGE 2 OF 2
BORING NUMBER B-3
PROJECT NUMBER 91-03317-A
PROJECT NAME Centennial Village
PROJECT LOCATION 180 El Camino Real, South San Francisco CLIENT The W. T. Mitchell Group
2001 Crow Canyon Road, Suite 210
San Ramon, CA 94583
Telephone: (925) 314-7100
Fax: (925) 314-7180
GB
3" ASPHALT PAVEMENT
6" AGGREGATE BASE
(SC) CLAYEY SAND : Dark greenish gray, moist
R-Value = 20
Bottom of borehole at 5.0 feet.
NOTES
GROUND ELEVATION 37.1 ft
LOGGED BY DE
DRILLING METHOD Mobile B-53
HOLE SIZE 8"
DRILLING CONTRACTOR Exploration Geoservices Inc. GROUND WATER LEVELS:
CHECKED BY CTD
DATE STARTED 9/9/14 COMPLETED 9/9/14
AT TIME OF DRILLING --- AT END OF DRILLING --- NFGW encountered AFTER DRILLING --- SAMPLE TYPE NUMBER RECOVERY % (RQD)
DRY UNIT WT.
(pcf)
MOISTURE
CONTENT (%)
LIQUID
LIMIT
PLASTIC
LIMIT
PLASTICITY
INDEX
FINES CONTENT
(%)
ATTERBERG
LIMITS
PLASTICITY
INDEX
GRAPHIC
LOG
DEPTH
(ft)
0 5
MATERIAL DESCRIPTION
SPT BLOW
COUNTS
(N VALUE)
POCKET PEN.
(tsf)
PAGE 1 OF 1
BORING NUMBER B-4
PROJECT NUMBER 91-03317-A
PROJECT NAME Centennial Village
PROJECT LOCATION 180 El Camino Real, South San Francisco CLIENT The W. T. Mitchell Group
2001 Crow Canyon Road, Suite 210
San Ramon, CA 94583
Telephone: (925) 314-7100
Fax: (925) 314-7180
MC
5-1
MC
5-2
MC
5-3
SPT
5-4
SPT
5-5
105 6
18 2.5" ASPHALT PAVEMENT
6" AGGREGATE BASE
(SM) SILTY SAND : Light yellowish & orangish brown, damp, cemented, w/ pea gravels, very dense
(ML) SANDY SILT : Brown, moist, w/ trace organics, dense (SM) SILTY SAND : Orangish brown, moist, cemented, dense Becomes yellowish & orangish brown, moist, slightly cemented, very fine-grained
Becomes light orangish-brown, fine-to-medium grained, medium dense, w/ silt and trace fine gravel
(SM) SILTY SAND : Brownish-gray, moist, fine-grained, very dense 12-31-35
(66)
9-16-23
(39)
20-33-33
(66)
12-13-13
(26)
16-25-25
(50)
NOTES
GROUND ELEVATION 31.4 ft
LOGGED BY DE
DRILLING METHOD Mobile B-53
HOLE SIZE 8"
DRILLING CONTRACTOR Exploration Geoservices Inc. GROUND WATER LEVELS:
CHECKED BY CTD
DATE STARTED 9/10/14 COMPLETED 9/10/14
AT TIME OF DRILLING 38.50 ft / Elev -7.10 ft
AT END OF DRILLING 38.00 ft / Elev -6.60 ft
AFTER DRILLING --- SAMPLE TYPE NUMBER RECOVERY % (RQD)
DRY UNIT WT.
(pcf)
MOISTURE
CONTENT (%)
LIQUID
LIMIT
PLASTIC
LIMIT
PLASTICITY
INDEX
FINES CONTENT
(%)
ATTERBERG
LIMITS
(Continued Next Page)
PLASTICITY
INDEX
GRAPHIC
LOG
DEPTH
(ft)
0 5
10 15
20 25
MATERIAL DESCRIPTION
SPT BLOW
COUNTS
(N VALUE)
POCKET PEN.
(tsf)
PAGE 1 OF 2
BORING NUMBER B-5
PROJECT NUMBER 91-03317-A
PROJECT NAME Centennial Village
PROJECT LOCATION 180 El Camino Real, South San Francisco CLIENT The W. T. Mitchell Group
2001 Crow Canyon Road, Suite 210
San Ramon, CA 94583
Telephone: (925) 314-7100
Fax: (925) 314-7180
SPT
5-6
SPT
5-7
(SM) SILTY SAND : Brownish-gray, moist, fine-grained, very dense (continued)
(CL) SANDY CLAY : Bluish-gray w/ brown, moist, very stiff (SP) SAND : Orangish-brown, fine to medium grained, wet, dense, w/ clay
Bottom of borehole at 40.0 feet.
8-12-12
(24)
10-16-20
(36)
SAMPLE TYPE
NUMBER
RECOVERY %
(RQD)
DRY UNIT WT.
(pcf)
MOISTURE
CONTENT (%)
LIQUID
LIMIT
PLASTIC
LIMIT
PLASTICITY
INDEX
FINES CONTENT
(%)
ATTERBERG
LIMITS
PLASTICITY
INDEX
GRAPHIC
LOG
DEPTH
(ft)
25 30
35 40
MATERIAL DESCRIPTION
SPT BLOW
COUNTS
(N VALUE)
POCKET PEN.
(tsf)
PAGE 2 OF 2
BORING NUMBER B-5
PROJECT NUMBER 91-03317-A
PROJECT NAME Centennial Village
PROJECT LOCATION 180 El Camino Real, South San Francisco CLIENT The W. T. Mitchell Group
2001 Crow Canyon Road, Suite 210
San Ramon, CA 94583
Telephone: (925) 314-7100
Fax: (925) 314-7180
MC
6-1
MC
6-2
MC
6-3
SPT
6-4
SPT
6-5
SPT
6-6
103
106
110
16 12
18 18
3" ASPHALT PAVEMENT
6" AGGREGATE BASE
(SM) SILTY SAND : Light yellowish brown, moist, medium dense Becomes orangeish brown, very fine grained, dense
c = 145 psf, phi = 43.7 degrees
Becomes gray w/ orange streaks, trace clay
Becomes very moist, w/ small layers of medium-grained sand (CL) SANDY CLAY : Orangeish brown, moist, trace fine gravels, very stiff
Becomes orangeish brown and gray w/ small black veins
7-10-12
(22)
8-10-20
(30)
5-11-20
(31)
7-12-14
(26)
4-6-11
(17)
5-7-10
(17)
NOTES
GROUND ELEVATION 38.5 ft
LOGGED BY DE
DRILLING METHOD Mobile B-53
HOLE SIZE 8"
DRILLING CONTRACTOR Exploration Geoservices Inc. GROUND WATER LEVELS:
CHECKED BY CTD
DATE STARTED 9/10/14 COMPLETED 9/10/14
AT TIME OF DRILLING 33.00 ft / Elev 5.50 ft
AT END OF DRILLING 31.00 ft / Elev 7.50 ft
AFTER DRILLING --- SAMPLE TYPE NUMBER RECOVERY % (RQD)
DRY UNIT WT.
(pcf)
MOISTURE
CONTENT (%)
LIQUID
LIMIT
PLASTIC
LIMIT
PLASTICITY
INDEX
FINES CONTENT
(%)
ATTERBERG
LIMITS
(Continued Next Page)
PLASTICITY
INDEX
GRAPHIC
LOG
DEPTH
(ft)
0 5
10 15
20 25
MATERIAL DESCRIPTION
SPT BLOW
COUNTS
(N VALUE)
POCKET PEN.
(tsf)
PAGE 1 OF 2
BORING NUMBER B-6
PROJECT NUMBER 91-03317-A
PROJECT NAME Centennial Village
PROJECT LOCATION 180 El Camino Real, South San Francisco CLIENT The W. T. Mitchell Group
2001 Crow Canyon Road, Suite 210
San Ramon, CA 94583
Telephone: (925) 314-7100
Fax: (925) 314-7180
SPT
6-7
SPT
6-8
(CL) SANDY CLAY : Orangeish brown, moist, trace fine gravels, very stiff (continued)
(CL) SANDY CLAY w/ CLAYEY SAND LAYERS : Gray w/ orange
brown streaks, very moist, very stiff
(CL-CH) FAT CLAY : Black, wet, medium to high plasticity, stiff Bottom of borehole at 35.0 feet.
5-6-9
(15)
4-5-5
(10)
SAMPLE TYPE
NUMBER
RECOVERY %
(RQD)
DRY UNIT WT.
(pcf)
MOISTURE
CONTENT (%)
LIQUID
LIMIT
PLASTIC
LIMIT
PLASTICITY
INDEX
FINES CONTENT
(%)
ATTERBERG
LIMITS
PLASTICITY
INDEX
GRAPHIC
LOG
DEPTH
(ft)
25 30
35 MATERIAL DESCRIPTION
SPT BLOW
COUNTS
(N VALUE)
POCKET PEN.
(tsf)
PAGE 2 OF 2
BORING NUMBER B-6
PROJECT NUMBER 91-03317-A
PROJECT NAME Centennial Village
PROJECT LOCATION 180 El Camino Real, South San Francisco CLIENT The W. T. Mitchell Group
2001 Crow Canyon Road, Suite 210
San Ramon, CA 94583
Telephone: (925) 314-7100
Fax: (925) 314-7180
MC
7-1
MC
7-2
MC
7-3
SPT
7-4
SPT
7-5
SPT
7-6
SPT
7-7
106
122
16 15
22 18 4
3" ASPHALT PAVEMENT
9" AGGREGATE BASE
(CL) LEAN CLAY : Dark brown, moist, very stiff
(SM) SILTY SAND : Light yellowish brown, moist, medium dense Becomes light brown with orange streaks, slightly plastic Becomes brown color, w/ clay, very moist
(SC) CLAYEY SAND : Brown, moist, dense, trace gravel
(CL) SANDY CLAY : Brown, moist, very dense, trace gravel (CL-ML) SILTY CLAY : Mottled reddish brown and brown, moist, stiff, with sand
Becomes very stiff
Bottom of borehole at 30.0 feet.
3-7-10
(17)
6-9-12
(21)
6-8-10
(18)
9-13-20
(33)
8-12-13
(25)
5-6-7
(13)
7-10-15
(25)
NOTES
GROUND ELEVATION 39.8 ft
LOGGED BY DE
DRILLING METHOD Mobile B-53
HOLE SIZE 8"
DRILLING CONTRACTOR Exploration Geoservices Inc. GROUND WATER LEVELS:
CHECKED BY CTD
DATE STARTED 9/9/14 COMPLETED 9/9/14
AT TIME OF DRILLING --- AT END OF DRILLING --- No Groundwater Encountered.
AFTER DRILLING --- SAMPLE TYPE NUMBER RECOVERY % (RQD)
DRY UNIT WT.
(pcf)
MOISTURE
CONTENT (%)
LIQUID
LIMIT
PLASTIC
LIMIT
PLASTICITY
INDEX
FINES CONTENT
(%)
ATTERBERG
LIMITS
PLASTICITY
INDEX
GRAPHIC
LOG
DEPTH
(ft)
0 5
10 15
20 25
30 MATERIAL DESCRIPTION
SPT BLOW
COUNTS
(N VALUE)
POCKET PEN.
(tsf)
PAGE 1 OF 1
BORING NUMBER B-7
PROJECT NUMBER 91-03317-A
PROJECT NAME Centennial Village
PROJECT LOCATION 180 El Camino Real, South San Francisco CLIENT The W. T. Mitchell Group
2001 Crow Canyon Road, Suite 210
San Ramon, CA 94583
Telephone: (925) 314-7100
Fax: (925) 314-7180
MC
8-1
MC
8-2
MC
8-3
SPT
8-4
SPT
8-5
SPT
8-6
SPT
8-7
119
112
10 6
16 2.5" ASPHALT PAVEMENT
6.5" AGGREGATE BASE
(SM) SILTY SAND : Light yellowish brown, damp to moist, dense, slightly cemented and slightly plastic
Becomes cemented
Becomes gray w/ orange brown streaks, very fine grained, w/ small layers of sandy silt
Becomes gray, trace clay
(SM) CEMENTED SILTY SAND : Brown, damp to moist, very
dense, w/ crushed rock
(CL) SANDY CLAY : Dark gray, moist to very moist, very stiff, trace pea gravel
(SM) SILTY SAND : Very dark greenish gray, very moist to wet, w/ gravel, slightly plastic, medium dense
Bottom of borehole at 30.0 feet.
10-16-20
(36)
20-49-49
(98)
10-14-12
(26)
10-13-21
(34)
50 7-9-14
(23)
9-10-13
(23)
NOTES
GROUND ELEVATION 37.2 ft
LOGGED BY DE
DRILLING METHOD Mobile B-53
HOLE SIZE 8"
DRILLING CONTRACTOR Exploration Geoservices Inc. GROUND WATER LEVELS:
CHECKED BY CTD
DATE STARTED 9/10/14 COMPLETED 9/10/14
AT TIME OF DRILLING --- AT END OF DRILLING 30.00 ft / Elev 7.20 ft AFTER DRILLING --- SAMPLE TYPE NUMBER RECOVERY % (RQD)
DRY UNIT WT.
(pcf)
MOISTURE
CONTENT (%)
LIQUID
LIMIT
PLASTIC
LIMIT
PLASTICITY
INDEX
FINES CONTENT
(%)
ATTERBERG
LIMITS
PLASTICITY
INDEX
GRAPHIC
LOG
DEPTH
(ft)
0 5
10 15
20 25
30 MATERIAL DESCRIPTION
SPT BLOW
COUNTS
(N VALUE)
POCKET PEN.
(tsf)
PAGE 1 OF 1
BORING NUMBER B-8
PROJECT NUMBER 91-03317-A
PROJECT NAME Centennial Village
PROJECT LOCATION 180 El Camino Real, South San Francisco CLIENT The W. T. Mitchell Group
2001 Crow Canyon Road, Suite 210
San Ramon, CA 94583
Telephone: (925) 314-7100
Fax: (925) 314-7180
tst
V
CAI.IFORNIA PUSH
TECHNOI.OGIES
coli{omio Push Tehnolosies Inc.
104 Consl uiion Dr ve 5u re 2
Meno Po.l CA 94025
of{i@ 050 854 0300
Id: 650 854 0301
w.cp'inccom
Code penctration testing and soil samplitrg methods description.
Ris Descriotion
Our services are based on the state-of-the-art, Geoprobe Model 6625CPT rig, a limited-access, self-anchoring 20-ton push capacity, track-mounted push platform for dedicated ceotechnical CPT applications with the unique and valuable added ability to quickly perform intermiftent or continuousoil sampling.
Weight=-9,500pounds
Surface load ='4.5 psi
Push capaciry =
- 20 tons; self-anchoring achieved using l0- or l5-inch diameter helical soil anchors driven 4- to | 0-feet into the soil
Sampling hammer percussion [ate: 32 Hz & 20,000 lbs force/blow Length - - 12 feet; Width =
- 7 leet
Height (folded): 7 feet; H€ight (unfolded) : 14 Get
CPT Description
Our Geoprobe 6625CPT incorporates the Swedish-made Geotech AB Con€ PeDetration Tesling tools which meet the ASTM D-577E Standard Test Method for Performine Electronic FrictioD Cone and Piezocone Penetration Testing of Soils. Cones have l0 cm'? tip;and 150 cm'? friction sleeves, and include a porous filter and pressurc s€nsor located in the u2 position directly behind the cone- The cone and porous filter are satumted under vacuum with glycerin to promote rapid equilibration with in-situ pore pressurcs. Cones are advanced attheASTM standard rateof2 cm/second. Baseline readings are performed both befote and after each push to check for load celldr;ft. The cone measures bearing (ma-\ load = I00 MPa - 1044 TSF), friction sle€ve (max Ioad = |.0 MPa - 10.4 TSF), and dynamic pore pressure (max load = 2.5 MPa- 363 psi) at 2 cm or 4 cm intervsls (client's choice) and this data is plotted in real-time and recorded on a laptop computer adjacent to the pLrsh platform. Holes are grouted upon completion ofeach push, or at the end of each day, as site conditions and regulations wanart.
The basic equation to determine the depth to the free water surface from th€ porc pressure dissipation test is;
Depth to phreatic surface = lDissipation depth] [equilibrium pore pressure / unit weight ofH2O x unit conversation factor]
l) Surface elevation is always assumed to be 0 l-eet
2) Dissipation depth = the depth (feet) below surface elevation where the cone advancement was paused while waiting for equilibrium pore pressure to be achieved 3) Equilibrium pore p!9$ur9 = the por€ pressure after an elapsed time where no increase or decrease in pore pressure is occuring, in pounds per square inch (psi) 4) Unit weight ofwater = 62.3 pounds per cubic foot (lb/ft^3) 5) Unit conversion factor (for dimensional analysis): I psi: 144 lblft^3 CPT lnc. ncttu<ls dcscript,on doc Ju.e25,2008
From the dissipation plots, simply read the dissipation depth and dissipated pressure for the values to plug into the equation above. On the plots, pore pressure (psi) is on the abscissand log time (seconds) is on the ordinate.
Samolins I)escrintion
Geoprobe@ brand Dual Tube Sampling Systems are emcient methods ofcollecting continuous soil cores with the added benefit ofa cased hole. Dual tube sampling uses two sets of probe rods to collect continuous oil cores. One set of rods is driven into the ground as an outer casing (2.2 or 3.25 inches in diam€ter). These rods receive the driving forc€ llom the hammer and provide a sealed hole from which soil samples may be recovered without the threat of cross contamination.
The second, smaller set of rods are placed insid€ the outer casing. The smaller rods hold a sample liner in place as the outer casing is driven one sampling interval. The small rods are then retracted to ret ;eve the filled liner. Soi I samDles are collected in I .85-inch diameter or I . 125- inch diameter clear PVC samDle sheaths.
Interpretations
Soil behaviorrype (SBT), SP'I N60 energy ratio, undrained shear strength, OCR, and unil weights are calculated and/or are interpretations generated by the CPT-Pro software based on empirioal relationships derived in the following references:
P.K. Robertson, R.G. Campanella" D. Cillespie, and J. Greig, 1986, Use ofPiezometer Cone Data" Proceedings ofthe ASCE Sp€cialty Conference In Situ '86: Use ofln Situ Tests in Geotechnical Ensineerins; pp. 1263-1280.
P.K. Roberston, 1990, Soil Classification Using the Cone Penetmtion Test, Canadian Geotechnical Joumal.27(l), pp. ls l- 158.
T. Lunne. P.K. Robertson, and J-J.M. Powell, 1997, Cone Penetration in Ceotechnical Pmctice.
Taylor and l'rancis Publishi|lg.
CPT Inc. makes no recommendation on which soil behavior type analysis is "most-corect". The engineer should be aware ofthe limitations of using CPT data to derive soil behavior type and other engineering parameters and is encouraged to r€view the above refeaences to better understand the applicability and limitations ofCPT data. [t is sometimes not possible to determinc soil type based solely on tip resistance, sleeve friction, and dynamic pore pressure response, and confirmatory samples may be required.
Please do not hesitate to contact CPT Inc. ifvou hav€ questions.
Sincerely,
John Rogi€
President
CalifomiaPush Technologies, Inc.
CPl lnc methods dBcnption.doc
ct)
Lr
''- 100
I
g10
345
Friction r^tio (oA)
Zone Soil Behavior Tlpe
I
2 5
6 7
8 9
10 1l
t2
sensitive fine grained
organic material
clay
silty clay to clay
clayey silt to silty clay
sandy silt to clayey silt
silty sand to sandy silt
sand to silty sand
sand
gravelly sand to sand
very stiff line grained (overconsolidated or cemented)
sand to clayey sand (overconsolidated or cemented)
Source: Robcrtson, nK., Campanella, R.G., Gillespie' D.' end Greig' J., 1986' Use of Piezomercr Cone Data.
Proceedings of the ASCE Specialty Cooference In Situ 86: U6e of In Situ Tes.s in Geotechnical Engineering r-llt-f.| V
CALIFORNIA PUSH
TECH NOLOGIES
INCORP
Soil Behavior Type (SBT) Model
0 100200 300 400
qc [T/ft^2]
0 5
10 15
20 25
30 35
40 45
50 Depth [ft]
0 2.0 4.0 6.0
fs [T/ft^2]
-10 0 10 20
u2 [lb/in^2]
0 1.0 2.0 3.0
Su(qc) [T/ft^2]
0 20 40 60 80 100
N60 [blows/ft]
Test no:
CPT-1
Project ID:
9103317A
Client:
Geosphere
Project:
Centenial Village
Location: Position:
South San Francisco, California
Ground level:
Date:
9/9/2014
Scale:
1 : 75
Page:
1/1
Fig:
File:
CPT-1.cpd
Classification by
Robertson 1986
Clay (3)
Clayey silt to silty clay (5)
Very stiff fine grained (11)
Clay (3)
Silty sand to sandy silt (7)
Clayey silt to silty clay (5)
Silty sand to sandy silt (7)
Sandy silt to clayey silt (6)
Silty sand to sandy silt (7)
Sand to silty sand (8)
Silty sand to sandy silt (7)
Sandy silt to clayey silt (6)
Silty sand to sandy silt (7)
Clayey silt to silty clay (5)
Sand to silty sand (8)
Sandy silt to clayey silt (6)
Sand to silty sand (8)
Sandy silt to clayey silt (6)
Clay (3)
Sand to silty sand (8)
Silty sand to sandy silt (7)
Sand to silty sand (8) Silty sand to sandy silt (7)
Clay (3)
Silty clay to clay (4)
Silty clay to clay (4)
Clayey silt to silty clay (5)
Clayey silt to silty clay (5)
Silty clay to clay (4)
Clayey silt to silty clay (5)
Clay (3)
Silty sand to sandy silt (7)
Sandy silt to clayey silt (6)
Silty sand to sandy silt (7)
Sand to silty sand (8)
Silty sand to sandy silt (7)
Silty sand to sandy silt (7)
Sandy silt to clayey silt (6)
Silty sand to sandy silt (7)
Sand to silty sand (8)
Sand (9)
Sandy silt to clayey silt (6) Very stiff fine grained (11) Very stiff fine grained (11)
Sand to silty sand (8)
Silty sand to sandy silt (7)
0 100200 300 400
qc [T/ft^2]
0 5
10 15
20 25
30 35
40 45
50 Depth [ft]
0 2.0 4.0 6.0
fs [T/ft^2]
-10 0 10 20
u2 [lb/in^2]
0 1.0 2.0 3.0
Su(qc) [T/ft^2]
0 20 40 60 80 100
N60 [blows/ft]
Test no:
CPT-2
Project ID:
9103317A
Client:
Geosphere
Project:
Centenial Village
Location: Position:
South San Francisco, California
Ground level:
Date:
9/9/2014
Scale:
1 : 75
Page:
1/1
Fig:
File:
CPT-2.cpd
U2
Sleeve area [cm2]: 150
Tip area [cm2]: 10
Cone No: 4141
Classification by
Robertson 1986
Clayey silt to silty clay (5)
Clay (3)
Sandy silt to clayey silt (6)
Silty sand to sandy silt (7)
Sandy silt to clayey silt (6)
Clay (3)
Sandy silt to clayey silt (6)
Clayey silt to silty clay (5)
Silty sand to sandy silt (7)
Clayey silt to silty clay (5)
Sandy silt to clayey silt (6)
Clay (3)
Silty sand to sandy silt (7)
Silty sand to sandy silt (7)
Silty sand to sandy silt (7)
Clay (3)
Sandy silt to clayey silt (6)
Silty sand to sandy silt (7)
Sandy silt to clayey silt (6)
Silty sand to sandy silt (7)
Clayey silt to silty clay (5)
Clay (3)
Sandy silt to clayey silt (6)
Clayey silt to silty clay (5)
Sandy silt to clayey silt (6)
Clayey silt to silty clay (5)
Silty clay to clay (4)
Silty sand to sandy silt (7)
Sandy silt to clayey silt (6)
Sand to silty sand (8)
Silty sand to sandy silt (7)
Sand to silty sand (8)
Sandy silt to clayey silt (6)
Silty sand to sandy silt (7)
Sand to silty sand (8)
Silty sand to sandy silt (7)
Sand to silty sand (8)
Silty sand to sandy silt (7)
Sand to clayey sand (12)
0 100200 300 400
qc [T/ft^2]
0 5
10 15
20 25
30 35
40 45
50 Depth [ft]
0 2.0 4.0 6.0
fs [T/ft^2]
-10 0 10 20
u2 [lb/in^2]
0 1.0 2.0 3.0
Su(qc) [T/ft^2]
0 20 40 60 80 100
N60 [blows/ft]
Test no:
CPT-3
Project ID:
9103317A
Client:
Geosphere
Project:
Centenial Village
Location: Position:
South San Francisco, California
Ground level:
Date:
9/10/2014
Scale:
1 : 75
Page:
1/1
Fig:
File:
CPT-3.cpd
U2
Sleeve area [cm2]: 150
Tip area [cm2]: 10
Cone No: 4170
Classification by
Robertson 1986
Clayey silt to silty clay (5)
Clay (3)
Very stiff fine grained (11)
Clayey silt to silty clay (5)
Silty sand to sandy silt (7)
Sandy silt to clayey silt (6)
Silty sand to sandy silt (7)
Sandy silt to clayey silt (6)
Silty sand to sandy silt (7)
Sand to clayey sand (12)
Sand (9)
Clay (3)
Sandy silt to clayey silt (6)
Sand to silty sand (8)
Sand (9)
Sand to silty sand (8)
Sandy silt to clayey silt (6)
Silty sand to sandy silt (7)
Sand to silty sand (8)
Silty sand to sandy silt (7)
Sandy silt to clayey silt (6)
Silty sand to sandy silt (7)
Sand to silty sand (8)
Clay (3)
Clayey silt to silty clay (5)
Sandy silt to clayey silt (6)
Clayey silt to silty clay (5)
Clay (3)
Silty clay to clay (4)
Clay (3)
Silty clay to clay (4)
Clay (3)
Sand to silty sand (8)
Sandy silt to clayey silt (6)
Silty sand to sandy silt (7)
Silty clay to clay (4)
Sandy silt to clayey silt (6) Clayey silt to silty clay (5) Silty clay to clay (4)
Clayey silt to silty clay (5)
Silty clay to clay (4)
Clayey silt to silty clay (5)
Sand to clayey sand (12) Very stiff fine grained (11)
Clay (3)
Very stiff fine grained (11)
Very stiff fine grained (11)
0 100200 300 400
qc [T/ft^2]
0 5
10 15
20 25
30 35
40 45
50 Depth [ft]
0 2.0 4.0 6.0
fs [T/ft^2]
-10 0 10 20
u2 [lb/in^2]
0 1.0 2.0 3.0
Su(qc) [T/ft^2]
0 20 40 60 80 100
N60 [blows/ft]
Test no:
CPT-4
Project ID:
9103317A
Client:
Geosphere
Project:
Centenial Village
Location: Position:
South San Francisco, California
Ground level:
Date:
9/9/2014
Scale:
1 : 75
Page:
1/1
Fig:
File:
CPT-4.cpd
U2
Sleeve area [cm2]: 150
Tip area [cm2]: 10
Cone No: 4141
Classification by
Robertson 1986
Sandy silt to clayey silt (6)
Very stiff fine grained (11)
Clayey silt to silty clay (5)
Sandy silt to clayey silt (6)
Silty sand to sandy silt (7)
Clayey silt to silty clay (5)
Sandy silt to clayey silt (6)
Silty sand to sandy silt (7)
Clayey silt to silty clay (5)
Silty sand to sandy silt (7)
Sandy silt to clayey silt (6)
Silty sand to sandy silt (7)
Clayey silt to silty clay (5)
Sand to silty sand (8)
Sandy silt to clayey silt (6)
Silty sand to sandy silt (7)
Sandy silt to clayey silt (6)
Clayey silt to silty clay (5)
Sandy silt to clayey silt (6)
Sand to silty sand (8)
Clay (3)
Clayey silt to silty clay (5)
Sandy silt to clayey silt (6)
Sandy silt to clayey silt (6)
Silty sand to sandy silt (7)
Sandy silt to clayey silt (6)
Clay (3)
Very stiff fine grained (11)
Silty sand to sandy silt (7)
Sand to silty sand (8)
Sand to silty sand (8)
Silty sand to sandy silt (7)
Clay (3)
Sand to silty sand (8)
Sand to clayey sand (12)
Sand to silty sand (8)
Sand (9)
Clayey silt to silty clay (5)
Very stiff fine grained (11)
Clay (3)
Clay (3)
Clay (3)
Clay (3)
Very stiff fine grained (11)
Sand to clayey sand (12)
0 100200 300 400
qc [T/ft^2]
0 5
10 15
20 25
30 35
40 45
50 Depth [ft]
0 2.0 4.0 6.0
fs [T/ft^2]
-10 0 10 20
u2 [lb/in^2]
0 1.0 2.0 3.0
Su(qc) [T/ft^2]
0 20 40 60 80 100
N60 [blows/ft]
Test no:
CPT-5
Project ID:
9103317A
Client:
Geosphere
Project:
Centenial Village
Location: Position:
South San Francisco, California
Ground level:
Date:
9/9/2014
Scale:
1 : 75
Page:
1/1
Fig:
File:
CPT-5.cpd
U2
Sleeve area [cm2]: 150
Tip area [cm2]: 10
Cone No: 4141
Classification by
Robertson 1986
Very stiff fine grained (11)
0 100200 300 400
qc [T/ft^2]
0 5
10 15
20 25
30 35
40 45
50 Depth [ft]
0 2.0 4.0 6.0
fs [T/ft^2]
-10 0 10 20
u2 [lb/in^2]
0 1.0 2.0 3.0
Su(qc) [T/ft^2]
0 20 40 60 80 100
N60 [blows/ft]
Test no:
CPT-6
Project ID:
9103317A
Client:
Geosphere
Project:
Centenial Village
Location: Position:
South San Francisco, California
Ground level:
Date:
9/10/2014
Scale:
1 : 75
Page:
1/1
Fig:
File:
CPT-6.cpd
U2
Sleeve area [cm2]: 150
Tip area [cm2]: 10
Cone No: 4170
Classification by
Robertson 1986
Silty sand to sandy silt (7)
Very stiff fine grained (11)
Silty sand to sandy silt (7)
Silty clay to clay (4)
Clayey silt to silty clay (5)
Sandy silt to clayey silt (6)
Clayey silt to silty clay (5)
Clay (3)
Sandy silt to clayey silt (6)
Clayey silt to silty clay (5)
Silty sand to sandy silt (7)
Sandy silt to clayey silt (6)
Silty sand to sandy silt (7)
Sandy silt to clayey silt (6)
Silty sand to sandy silt (7)
Sand to silty sand (8)
Sandy silt to clayey silt (6) Clayey silt to silty clay (5) Silty sand to sandy silt (7)
Silty sand to sandy silt (7)
Sandy silt to clayey silt (6)
Silty sand to sandy silt (7)
Clayey silt to silty clay (5)
Silty clay to clay (4)
Clay (3)
Silty clay to clay (4)
Clay (3)
Silty clay to clay (4)
Clay (3)
Silty sand to sandy silt (7)
Silty sand to sandy silt (7)
Sandy silt to clayey silt (6)
Sand to silty sand (8)
Sandy silt to clayey silt (6)
Sand to silty sand (8)
Sand to silty sand (8)
Silty sand to sandy silt (7)
Silty sand to sandy silt (7)
Sand to silty sand (8) Sandy silt to clayey silt (6) Silty sand to sandy silt (7) Sand to silty sand (8)
Sand (9)
Sand to silty sand (8)
Clayey silt to silty clay (5)
Clay (3)
Silty clay to clay (4)
Clayey silt to silty clay (5)
Very stiff fine grained (11)
0 100200 300 400
qc [T/ft^2]
0 5
10 15
20 25
30 35
40 45
50 Depth [ft]
0 2.0 4.0 6.0
fs [T/ft^2]
-10 0 10 20
u2 [lb/in^2]
0 1.0 2.0 3.0
Su(qc) [T/ft^2]
0 20 40 60 80 100
N60 [blows/ft]
Test no:
CPT-7
Project ID:
9103317A
Client:
Geosphere
Project:
Centenial Village
Location: Position:
South San Francisco, California
Ground level:
Date:
9/9/2014
Scale:
1 : 75
Page:
1/1
Fig:
File:
CPT-7.cpd
U2
Sleeve area [cm2]: 150
Tip area [cm2]: 10
Cone No: 4141
Classification by
Robertson 1986
Sand to clayey sand (12)
Sandy silt to clayey silt (6)
Silty sand to sandy silt (7)
Sand to silty sand (8)
Silty sand to sandy silt (7)
Sand to clayey sand (12)
Silty sand to sandy silt (7)
Sandy silt to clayey silt (6)
Clayey silt to silty clay (5)
Sandy silt to clayey silt (6)
Silty sand to sandy silt (7)
Sand to silty sand (8)
Sandy silt to clayey silt (6)
Silty sand to sandy silt (7)
Clayey silt to silty clay (5)
Sandy silt to clayey silt (6)
Clay (3)
Sand to silty sand (8)
Sand (9)
Clay (3)
Clayey silt to silty clay (5)
Silty clay to clay (4)
Clay (3)
Clayey silt to silty clay (5)
Sandy silt to clayey silt (6)
Silty sand to sandy silt (7)
Sand to silty sand (8)
Silty sand to sandy silt (7)
Sand to silty sand (8)
Silty sand to sandy silt (7)
Sand to silty sand (8)
Sand to silty sand (8)
Sand to clayey sand (12)
Sandy silt to clayey silt (6)
Silty sand to sandy silt (7)
Sand to clayey sand (12)
Sand to clayey sand (12)
Sand to silty sand (8)
0 100200 300 400
qc [T/ft^2]
0 5
10 15
20 25
30 35
40 45
50 Depth [ft]
0 2.0 4.0 6.0
fs [T/ft^2]
-10 0 10 20
u2 [lb/in^2]
0 1.0 2.0 3.0
Su(qc) [T/ft^2]
0 20 40 60 80 100
N60 [blows/ft]
Test no:
CPT-8
Project ID:
9103317A
Client:
Geosphere
Project:
Centenial Village
Location: Position:
South San Francisco, California
Ground level:
Date:
9/9/2014
Scale:
1 : 75
Page:
1/1
Fig:
File:
CPT-8.cpd
U2
Sleeve area [cm2]: 150
Tip area [cm2]: 10
Cone No: 4141
Classification by
Robertson 1986
Sensitive fine grained (1)
Clay (3)
Very stiff fine grained (11)
Clay (3)
Clay (3)
Silty clay to clay (4)
Clay (3)
Sandy silt to clayey silt (6)
0 100200 300 400
qc [T/ft^2]
0 5
10 15
20 25
30 35
40 45
50 Depth [ft]
0 2.0 4.0 6.0
fs [T/ft^2]
-10 0 10 20
u2 [lb/in^2]
0 1.0 2.0 3.0
Su(qc) [T/ft^2]
0 20 40 60 80 100
N60 [blows/ft]
Test no:
CPT-9
Project ID:
9103317A
Client:
Geosphere
Project:
Centenial Village
Location: Position:
South San Francisco, California
Ground level:
Date:
9/9/2014
Scale:
1 : 75
Page:
1/1
Fig:
File:
CPT-9.cpd
U2
Sleeve area [cm2]: 150
Tip area [cm2]: 10
Cone No: 4141
Classification by
Robertson 1986
Sandy silt to clayey silt (6)
Silty sand to sandy silt (7)
Sandy silt to clayey silt (6)
Very stiff fine grained (11)
Sandy silt to clayey silt (6)
Very stiff fine grained (11)
Sand to clayey sand (12)
Very stiff fine grained (11)
Clay (3)
Very stiff fine grained (11)
Very stiff fine grained (11)
Sand to clayey sand (12)
Silty sand to sandy silt (7)
Very stiff fine grained (11)
Clay (3)
Silty clay to clay (4)
Clay (3)
Silty clay to clay (4)
Very stiff fine grained (11)
Clay (3)
Clayey silt to silty clay (5)
Very stiff fine grained (11)
Sand to clayey sand (12)
0 100200 300 400
qc [T/ft^2]
0 5
10 15
20 25
30 35
40 45
50 Depth [ft]
0 2.0 4.0 6.0
fs [T/ft^2]
-10 0 10 20
u2 [lb/in^2]
0 1.0 2.0 3.0
Su(qc) [T/ft^2]
0 20 40 60 80 100
N60 [blows/ft]
Test no:
CPT-10
Project ID:
9103317A
Client:
Geosphere
Project:
Centenial Village
Location: Position:
South San Francisco, California
Ground level:
Date:
9/10/2014
Scale:
1 : 75
Page:
1/1
Fig:
File:
CPT-10.cpd
U2
Sleeve area [cm2]: 150
Tip area [cm2]: 10
Cone No: 4170
Classification by
Robertson 1986
Sandy silt to clayey silt (6)
Clay (3)
Very stiff fine grained (11)
Sandy silt to clayey silt (6)
Clay (3)
Clayey silt to silty clay (5)
Clay (3)
Clayey silt to silty clay (5)
Very stiff fine grained (11)
Very stiff fine grained (11)
Clay (3)
Clay (3)
Clay (3)
Very stiff fine grained (11)
Clay (3)
Very stiff fine grained (11)
Clay (3)
Very stiff fine grained (11)
Sandy silt to clayey silt (6)
Very stiff fine grained (11)
Silty clay to clay (4)
Clay (3)
Silty clay to clay (4)
Very stiff fine grained (11)
Clay (3)
Very stiff fine grained (11)
Clay (3)
Very stiff fine grained (11)
Clay (3)
Very stiff fine grained (11)
Very stiff fine grained (11)
Clay (3)
Very stiff fine grained (11)
0 100200 300 400
qc [T/ft^2]
0 5
10 15
20 25
30 35
40 45
50 Depth [ft]
0 2.0 4.0 6.0
fs [T/ft^2]
-10 0 10 20
u2 [lb/in^2]
0 1.0 2.0 3.0
Su(qc) [T/ft^2]
0 20 40 60 80 100
N60 [blows/ft]
Test no:
CPT-11
Project ID:
9103317A
Client:
Geosphere
Project:
Centenial Village
Location: Position:
South San Francisco, California
Ground level:
Date:
9/10/2014
Scale:
1 : 75
Page:
1/1
Fig:
File:
CPT-11.cpd
U2
Sleeve area [cm2]: 150
Tip area [cm2]: 10
Cone No: 4170
Classification by
Robertson 1986
Very stiff fine grained (11)
Sand to clayey sand (12)
Very stiff fine grained (11)
Clay (3)
Very stiff fine grained (11)
Clay (3)
Very stiff fine grained (11)
Very stiff fine grained (11)
Very stiff fine grained (11)
Sand to clayey sand (12)
Sandy silt to clayey silt (6)
Silty sand to sandy silt (7)
0 100200 300 400
qc [T/ft^2]
0 5
10 15
20 25
30 35
40 45
50 Depth [ft]
0 2.0 4.0 6.0
fs [T/ft^2]
-10 0 10 20
u2 [lb/in^2]
0 1.0 2.0 3.0
Su(qc) [T/ft^2]
0 20 40 60 80 100
N60 [blows/ft]
Test no:
CPT-12
Project ID:
9103317A
Client:
Geosphere
Project:
Centenial Village
Location: Position:
South San Francisco, California
Ground level:
Date:
9/10/2014
Scale:
1 : 75
Page:
1/1
Fig:
File:
CPT-12.cpd
U2
Sleeve area [cm2]: 150
Tip area [cm2]: 10
Cone No: 4170
Classification by
Robertson 1986
Very stiff fine grained (11)
Sandy silt to clayey silt (6)
Very stiff fine grained (11)
Sandy silt to clayey silt (6)
Sandy silt to clayey silt (6)
Very stiff fine grained (11)
Sandy silt to clayey silt (6)
Very stiff fine grained (11)
Sand to silty sand (8)
0 100200 300 400
qc [T/ft^2]
0 5
10 15
20 25
30 35
40 45
50 Depth [ft]
0 2.0 4.0 6.0
fs [T/ft^2]
-10 0 10 20
u2 [lb/in^2]
0 1.0 2.0 3.0
Su(qc) [T/ft^2]
0 20 40 60 80 100
N60 [blows/ft]
Test no:
CPT-13
Project ID:
9103317A
Client:
Geosphere
Project:
Centenial Village
Location: Position:
South San Francisco
Ground level:
Date:
9/10/2014
Scale:
1 : 75
Page:
1/1
Fig:
File:
CPT-13.cpd
U2
Sleeve area [cm2]: 150
Tip area [cm2]: 10
Cone No: 4170
Classification by
Robertson 1986
Silty sand to sandy silt (7)
Sandy silt to clayey silt (6)
Silty sand to sandy silt (7)
Sandy silt to clayey silt (6)
Sandy silt to clayey silt (6) Silty sand to sandy silt (7) Very stiff fine grained (11)
Sandy silt to clayey silt (6)
Very stiff fine grained (11)
Silty sand to sandy silt (7)
Very stiff fine grained (11)
Sandy silt to clayey silt (6)
Sand to clayey sand (12)
Silty sand to sandy silt (7)
Sand to clayey sand (12)
Very stiff fine grained (11)
Clay (3)
Clay (3)
Silty clay to clay (4)
Clay (3)
Very stiff fine grained (11)
Clay (3)
Very stiff fine grained (11)
Silty sand to sandy silt (7)
Clay (3)
Silty sand to sandy silt (7)
Sand to clayey sand (12)
0 100200 300 400
qc [T/ft^2]
0 5
10 15
20 25
30 35
40 45
50 Depth [ft]
0 2.0 4.0 6.0
fs [T/ft^2]
-10 0 10 20
u2 [lb/in^2]
0 1.0 2.0 3.0
Su(qc) [T/ft^2]
0 20 40 60 80 100
N60 [blows/ft]
Test no:
CPT-14
Project ID:
9103317A
Client:
Geosphere
Project:
Centenial Village
Location: Position:
South San Francisco, California
Ground level:
Date:
9/10/2014
Scale:
1 : 75
Page:
1/1
Fig:
File:
CPT-14.cpd
U2
Sleeve area [cm2]: 150
Tip area [cm2]: 10
Cone No: 4170
Classification by
Robertson 1986
Sandy silt to clayey silt (6)
Silty sand to sandy silt (7)
Sandy silt to clayey silt (6)
Silty sand to sandy silt (7)
Very stiff fine grained (11)
Sand to clayey sand (12)
Silty sand to sandy silt (7)
Sandy silt to clayey silt (6)
Silty sand to sandy silt (7)
0 100200 300 400
qc [T/ft^2]
0 5
10 15
20 25
30 35
40 45
50 Depth [ft]
0 2.0 4.0 6.0
fs [T/ft^2]
-10 0 10 20
u2 [lb/in^2]
0 1.0 2.0 3.0
Su(qc) [T/ft^2]
0 20 40 60 80 100
N60 [blows/ft]
Test no:
CPT-15
Project ID:
9103317A
Client:
Geosphere
Project:
Centenial Village
Location: Position:
South San Francisco, California
Ground level:
Date:
9/10/2014
Scale:
1 : 75
Page:
1/1
Fig:
File:
CPT-15.cpd
U2
Sleeve area [cm2]: 150
Tip area [cm2]: 10
Cone No: 4170
Classification by
Robertson 1986
Very stiff fine grained (11)
Sand to clayey sand (12)
Sand to clayey sand (12)
Very stiff fine grained (11)
Clay (3)
Very stiff fine grained (11)
Very stiff fine grained (11)
Sand to clayey sand (12)
0 100200 300 400
qc [T/ft^2]
0 5
10 15
20 25
30 35
40 45
50 Depth [ft]
0 2.0 4.0 6.0
fs [T/ft^2]
-10 0 10 20
u2 [lb/in^2]
0 1.0 2.0 3.0
Su(qc) [T/ft^2]
0 20 40 60 80 100
N60 [blows/ft]
Test no:
CPT-16
Project ID:
9103317A
Client:
Geosphere
Project:
Centenial Village
Location: Position:
South San Francisco, California
Ground level:
Date:
9/10/2014
Scale:
1 : 75
Page:
1/1
Fig:
File:
CPT-16.cpd
U2
Sleeve area [cm2]: 150
Tip area [cm2]: 10
Cone No: 4170
Classification by
Robertson 1986
Very stiff fine grained (11)
Very stiff fine grained (11)
Sand to clayey sand (12)
Very stiff fine grained (11)
Sand to clayey sand (12)
Very stiff fine grained (11)
Sand to clayey sand (12)
Very stiff fine grained (11)
Clay (3)
Very stiff fine grained (11)
Very stiff fine grained (11)
Geo-Engineering Solutions
Project 180 El Camino Real Operator JM-IY Filename SDF(445).cptJob Number 98-13333 Cone Number DDG1596 GPSHole Number CPT-01A Date and Time 10/25/2021 3:03:17 PM Maximum Depth 50.52 ftEST GW Depth During Test 17.00 ft Net Area Ratio .8Cone Size 15cm squared Soil Behavior Referance *Soil behavior type and SPT based on data from UBC-1983 0 10 20 30 40 50 60 70
0 600
TIP
TSF 0 12
FRICTION
TSF 0 10
Fs/Qt
% 0 250
SPT N
0 12
1 - sensitive fine grained 2 - organic material 3 - clay 4 - silty clay to clay 5 - clayey silt to silty clay 6 - sandy silt to clayey silt 7 - silty sand to sandy silt 8 - sand to silty sand 9 - sand 10 - gravelly sand to sand 11 - very stiff fine grained (*)12 - sand to clayey sand (*)
CPT DATA
DEPTH
(ft)
SOIL
BEHAVIOR
TYPE
Geo-Engineering Solutions
Project 180 El Camino Real Operator JM-IY Filename SDF(444).cptJob Number 98-13333 Cone Number DDG1596 GPSHole Number CPT-02A Date and Time 10/25/2021 1:38:55 PM Maximum Depth 62.34 ftEST GW Depth During Test 20.00 ft Net Area Ratio .8Cone Size 15cm squared Soil Behavior Referance *Soil behavior type and SPT based on data from UBC-1983 0 10 20 30 40 50 60 70
0 600
TIP
TSF 0 12
FRICTION
TSF 0 10
Fs/Qt
% 0 250
SPT N
0 12
1 - sensitive fine grained 2 - organic material 3 - clay 4 - silty clay to clay 5 - clayey silt to silty clay 6 - sandy silt to clayey silt 7 - silty sand to sandy silt 8 - sand to silty sand 9 - sand 10 - gravelly sand to sand 11 - very stiff fine grained (*)12 - sand to clayey sand (*)
CPT DATA
DEPTH
(ft)
SOIL
BEHAVIOR
TYPE
Geo-Engineering Solutions
Depth 4.99ftRef*
Arrival 7.34mSVelocity*
Depth 10.01ftRef 4.99ft
Arrival 12.66mSVelocity 735.72ft/S
Depth 15.03ftRef 10.01ft
Arrival 18.12mSVelocity 829.51ft/S
Depth 20.01ftRef 15.03ft
Arrival 24.92mSVelocity 695.53ft/S
Depth 25.03ftRef 20.01ft
Arrival 30.31mSVelocity 901.17ft/S
Depth 30.02ftRef 25.03ft
Arrival 36.09mSVelocity 843.76ft/S
Depth 35.01ftRef 30.02ft
Arrival 40.86mSVelocity 1029.96ft/S
Depth 40.03ftRef 35.01ft
Arrival 45.78mSVelocity 1007.78ft/S
Depth 45.51ftRef 40.03ft
Arrival 51.56mSVelocity 939.05ft/S
Depth 50.03ftRef 45.51ft
Arrival 55.78mSVelocity 1065.34ft/S
Depth 55.02ftRef 50.03ft
Arrival 60.70mSVelocity 1007.07ft/S
Depth 60.04ftRef 55.02ft
Arrival 64.76mSVelocity 1229.38ft/S
0 10 20 30 40 50 60 70 80 90 100
Depth 62.34ftRef 60.04ft
Arrival 66.25mSVelocity 1540.29ft/S
Time (mS)
Hammer to Rod String Distance (ft): 5.83
* = Not Determined
COMMENT:
CPT-02A 180 El Camino Real
Geo-Engineering Solutions
Project 180 El Camino Real Operator JM-IY Filename SDF(446).cptJob Number 98-13333 Cone Number DDG1596 GPSHole Number CPT-03A Date and Time 10/25/2021 3:57:12 PM Maximum Depth 50.69 ftEST GW Depth During Test 14.00 ft Net Area Ratio .8Cone Size 15cm squared Soil Behavior Referance *Soil behavior type and SPT based on data from UBC-1983 0 10 20 30 40 50 60 70
0 600
TIP
TSF 0 12
FRICTION
TSF 0 10
Fs/Qt
% 0 250
SPT N
0 12
1 - sensitive fine grained 2 - organic material 3 - clay 4 - silty clay to clay 5 - clayey silt to silty clay 6 - sandy silt to clayey silt 7 - silty sand to sandy silt 8 - sand to silty sand 9 - sand 10 - gravelly sand to sand 11 - very stiff fine grained (*)12 - sand to clayey sand (*)
CPT DATA
DEPTH
(ft)
SOIL
BEHAVIOR
TYPE
APPENDIX E
Laboratory Testing Results
Tested By: JH Checked By: JH
Mottled greenish gray and brown sandy clay 31 16 15 CL
2831-056.0 Haley & Aldrich, Inc.
MATERIAL DESCRIPTION LL PL PI %<#40 %<#200 USCS
Project No. Client: Remarks:
Project:
Figure
Source of Sample: HA-4-1 Depth: 6-6.5 PLASTICITY INDEX
0 10
20 30
40 50
60 LIQUID LIMIT
0 10 20 30 40 50 60 70 80 90 100 110
CL-ML CL or OL
CH or OH
ML or OL MH or OH
Dashed line indicates the approximate
upper limit boundary for natural soils
4 7 WATER CONTENT
29.4 29.8
30.2 30.6
31 31.4
31.8 32.2
32.6 33
33.4 NUMBER OF BLOWS
5 6 7 8 9 10 20 25 30 40
LIQUID AND PLASTIC LIMITS TEST REPORT ASTM D4318
180 El Camino
0204226-000-001-02
ASTM D-1140
PERCENT PASSING NO. 200 SIEVE REPORT
Client Name Haley & Aldrich, Inc.
Project Name 180 El Camino
Project Number 0204226-000-001-02
Boring Number HA-1-2 HA-2-2 HA-3-2 HA-5-3 HA-6-4
Sample Number
Depth (ft) 7.5-8 7.5-9 7.5-9 11-11.5 13.5-15
Percent of Soil Finer than No. 200 Sieve 54.6 46.1 35.2 29.7 34.5 Visual Classification Grayish brown sandy
silt
Grayish brown
silty sand
Grayish brown
silty sand
Dark brown silty
sand with AC
Gray silty sand
Date 03/02/22 03/02/22 03/02/22 03/02/22 03/02/22
Weight of Dry Soil + Pan (before wash) 237.8 199.4 580.5 372.8 196.5 Weight of Dry Soil + Pan (after wash) 135.6 131.0 442.4 287.4 146.4 Weight of Pan 50.5 51.1 188.1 84.6 51.0
Method A
Specimens Soaked Overnight without Deflocculating Agent Dry Mass Determined Directly
INSPECTION SERVICES, INC., BERKELEY, CA
APPENDIX F
Previous Testing Results
Summary Table of Boring Log by Others
Boring Designation Date Drilled Depth Interval
(feet) Soil Description Pertinent Test Results
0-2 LEAN CLAY (CL), light brown and gray,
stiff, moist, with fine sand (Fill)
LL=26, PI=9;
PP=1.0 ksf Undrained SS;
DD=100 pcf, MC=20%
2-4.5 CLAYEY SAND (SC), brown, medium
dense, moist, fine to medium sand (Fill) DD=121 pcf, MC=13%
4.5-8.5 SAND (SP-SM), light brown, medium
dense, fine to medium sand DD=101 pcf, MC=8%
8.5-13.5 SANDY SILT(ML), light brown, stiff,
moist
% Passing #200 = 50%
MC=24%
13.5-17.5 SILTY SAND (SM), dark grayish brown to
gray, loose to medium dense, moist
17.5-19
SAND with SILT (SP-SM), BROWN,
medium dense, moist, fine to medium
sand
MC=23%
19-21.5
SILTY SAND (SM), grayish brown,
medium dense to loose, moist, some
rootlets & clay
21.5-28
FAT CLAY (CH), dark gray, very stiff,
moist, some fine sand, moderate to
high plasticity
DD=88 pcf, MC=27%
PP=3.0 ksf Undrained SS
28-43 SILTY SAND (SM), gray, medium dense
to dense, moist, some organics
% Passing #200 = 31%
@31', 10%@36'
43-45.5 LEAN CLAY WITH SAND (CL), olive gray,
very stiff, moist
LB-1
(GW encountered
during drilling at 30')
10/29/2004
Project:
Project No. Client: Remarks:
MATERIAL DESCRIPTION LL PL PI %<#40 %<#200
LIQUID AND PLASTIC LIMITS TEST REPORT
Source: B7-1 Elev./Depth: 2'
Figure
LIQUID AND PLASTIC LIMITS TEST REPORT
COOPER TESTING LABORATORY
USCS
724-083 Geosphere Consultants
Olive Silty, Clayey SAND 22 418
Centennial Village - 91-03317-A
5 10 20 25 30 40 20.3
21.1 21.9
22.7 23.5
24.3 NUMBER OF BLOWS
WATER CONTENT
10 30 50 70 90 110
LIQUID LIMIT
10 20
30 40
50 60
PLASTICITY INDEX
4 7 CL-ML
CL or OL
CH or OH
ML or OL MH or OH
Dashed line indicates the approximate
upper limit boundary for natural soils
Project No.:
Project:
Client:
Cu
Cc
COEFFICIENTS
D10
D30
D60
GRAIN SIZE REMARKS:
SIEVE PERCENT FINER SIEVE PERCENT FINER SOIL DESCRIPTION % GRAVEL % SAND % SILT % CLAY USCS AASHTO LLPL
size size
number
Particle Size Distribution Report
10 20
30 40
50 60
70 80
90 0
100
PERCENT FINER
200 100 10 1 0.1 0.01 0.001
GRAIN SIZE - mm
6 in.3 in.2 in.1-1/2 in.1 in.3/4 in.1/2 in.3/8 in.#4#10#20#30#40#60#100#140#200 Figure
% COBBLES
724-083
Centennial Village - 91-03317-A
Geosphere Consultants
Source: B5-4 Elev./Depth: 15.5'
0.119
0.787
11.0 70.6 18.4
inches Yellowish Brown Silty SAND
COOPER TESTING LABORATORY
89.0 73.0
56.1 50.4
44.8 34.7
18.4 #4
#10
#30
#40
#50
#100
#200
100.0
97.1 3/4"
3/8"
Project No.:
Project:
Client:
Cu
Cc
COEFFICIENTS
D10
D30
D60
GRAIN SIZE REMARKS:
SIEVE PERCENT FINER SIEVE PERCENT FINER SOIL DESCRIPTION % GRAVEL % SAND % SILT % CLAY USCS AASHTO LLPL
size size
number
Particle Size Distribution Report
10 20
30 40
50 60
70 80
90 0
100
PERCENT FINER
200 100 10 1 0.1 0.01 0.001
GRAIN SIZE - mm
6 in.3 in.2 in.1-1/2 in.1 in.3/4 in.1/2 in.3/8 in.#4#10#20#30#40#60#100#140#200 Figure
% COBBLES
724-083
Centennial Village - 91-03317-A
Geosphere Consultants
Source: B1-4 Elev./Depth: 19'
0.0831
0.154
0.4 74.8 24.8
inches Greenish Gray Silty SAND
COOPER TESTING LABORATORY
Source: B2-5 Elev./Depth: 19'
0.108
63.6 36.4
Greenish Gray Silty SAND
Source: B3-4 Elev./Depth: 14.5'
0.0837
45.4 54.6
Very Dark Bluish Gray Sandy SILT
99.6 97.8
93.2 90.0
84.4 58.9
24.8 #4
#10
#30
#40
#50
#100
#200
3/8" 100.0 100.0
99.8 99.5
99.0 97.1
77.8 36.4
100.0
99.6 98.3
97.2 95.2
84.2 54.6
CTL Job #: Project #: By: MD
Client: Date: Checked: PJ
Project Name: Remolding Info:
Phi (deg) Ult. Phi (deg)
1 2 3 4
Boring: B6-2 B6-2 B6-2
Sample:
Depth (ft): 4.5 4.5 4.5
Normal Load (psf) 1000 3000 5000
Dry Mass of Specimen (g) 123.3 127.8 126.6
Initial Height (in) 1.02 1.00 1.02
Initial Diameter (in) 2.42 2.42 2.42
Initial Void Ratio 0.676 0.592 0.632
Initial Moisture (%) 16.0 11.5 16.2
Initial Wet Density (pcf) 116.7 118.0 120.0
Initial Dry Density (pcf) 100.6 105.9 103.3
Initial Saturation (%) 63.9 52.4 69.2
ΔHeight Consol (in) 0.0145 0.0271 0.0280
At Test Void Ratio 0.652 0.549 0.587
At Test Moisture (%) 21.8 17.6 20.7
At Test Wet Density (pcf) 124.4 128.1 128.3
At Test Dry Density (pcf) 102.1 108.9 106.3
At Test Saturation (%) 90.5 86.5 95.3
Strain Rate (%/min) 1.0 1.0 0.9
Strengths Picked at Peak Peak Peak
Shear Stress (psf) 1039 3369 4868
ΔHeight (in) at Peak
Ultimate Stress (psf)
©
Consolidated Undrained Direct Shear
(ASTM D3080M)
Geosphere Consultants
Centennial Village
724-083 91-03317-A
9/24/2014
*DS-CU* A fully undrained condition may not be attained in this test. ΔH is not measured during undrained direct shear tests.
Olive Silty
SAND
Visual
Description:
Olive Silty
SAND
Olive Silty
SAND
Remarks:
Specimen Data
Cohesion (psf) Ult. Cohesion (psf)
0 1000
2000
3000
4000
5000
6000
0.0 5.0 10.0 15.0 20.0
Shear Stress (psf)
Deformation (%)
Shear Stress vs. Deformation
Sample 1
Sample 2
Sample 3
Sample 4
0 2000
4000
6000
8000
0 2000 4000 6000 8000
Shear Stress, psf
Normal Load, psf
Shear Stress vs. Normal Load
Peak
Shear Stress
Ult. Stress
Ultimate
0.0000
0.2000
0.4000
0.6000
0.8000
1.0000
1.2000
0.0 5.0 10.0 15.0 20.0
Delta h (in)
Deformation (%)
Change in Height
Sample 1
Sample 2
Sample 3
Sample 4
Job No.: Date: 09/25/14 11.9%
Client: Tested MD
Project: Reduced RU
Sample Checked DC
Soil Type:
A B C D
109 208 500
1200 1200 1200
50 30 7
3178 3216 3161
2092 2102 2085
2.55 2.53 2.38
16.6 14.7 12.6
110.6 116.2 121.6
0.0 0.0 60.2
148 130 96
4.35 4 3.38
4 13 30
Turns Displacement
Dark Greenish Gray Clayey SAND
Weight of Mold, grams
Exudation Pressure, psi
724-083 Initial Moisture,
Geosphere Consultants
Centennial Village - 91-03317-A
Moisture Content, %
Specimen Number
Prepared Weight, grams
Final Water Added, grams/cc
Weight of Soil & Mold, grams
Height After Compaction, in.
psf Expansion
Pressure
R-value by
Stabilometer 20
20 Remarks:
B-4 @ 1-4'
Dry Density, pcf
R-value
Stabilometer @ 2000
Expansion Pressure, psf
Stabilometer @ 1000
0 100
200
300
400
500
600
700
800
900
1000
0 10
20 30
40 50
60 70
80 90
100
0 100 200 300 400 500 600 700 800
Expansion Pressure, psf
R-value
Exudation Pressure, psi
R-value
Expansion Pressure,
psf
R-value Test Report (Caltrans 301)
CTL # Date: PJ
Client: Project:
Remarks:
Chloride pH Sulfide Moisture
As Rec. Min Sat. mg/kg mg/kg % Qualitative At Test
Dry Wt. Dry Wt. Dry Wt. EH (mv) At Test by Lead %
Boring Sample, No. Depth, ft. ASTM G57 Cal 643 ASTM G57 ASTM D4327 ASTM D4327 ASTM D4327 ASTM G51 ASTM G200 Temp °C Acetate Paper ASTM D2216 B2,B4,B6,B7,B8 - 1.5-4 - - 1,908 29 93 0.0093 7.4 525 24 Negative 13.0 Yellowish Brown Clayey SAND Soil Visual Description
724-080
Centennial Village
Sample Location or ID Sulfate ORP
Tested By:
Corrosivity Tests Summary
(Redox)
PJ
91-03317-A
Resistivity @ 15.5 °C (Ohm-cm)
Proj. No:
9/18/2014 Checked:
Geosphere Consultants, Inc
APPENDIX D
PHASE I ESA AND PHASE I ESA UPDATE
Washington
Issaquah | Bellingham | Seattle
Oregon
Portland | Baker City
California
Oakland | Irvine
P:\2516 SteelWave Acquisitions\2516002 180 El Camino Real SSF\Deliverables\2021 Phase I ESA Udpate\2021-10 Phase I ESA Update Ltr.doc Your Challenges. Our Priority. | farallonconsulting.com October 21, 2021
Ianthe Schaub
SteelWave Acquisitions, LLC
101 California Street, Suite 800
San Francisco, California 94111
RE: PHASE I ENVIRONMENTAL SITE ASSESSMENT UPDATE
170 THROUGH 192 EL CAMINO REAL
SOUTH SAN FRANCISCO, CALIFORNIA
FARALLON PN: 2516-002
Dear Ianthe Schaub:
Farallon Consulting, L.L.C. (Farallon) prepared this Phase I Environmental Site Assessment Update (Phase I ESA Update) for the property located at 170 through 192 El Camino Real, South San Francisco, California (herein referred to as the Site) for SteelWave Acquisitions, LLC, (SteelWave), the User of this report. Farallon prepared a Phase I ESA for the Site dated December 14, 2020 (2020 Phase I ESA).1 A copy of the 2020 Phase I ESA Report is included as Attachment A.
OBJECTIVE
The objective of the Phase I ESA Update was to identify, to the extent feasible pursuant to the scope of work outlined in the American Society for Testing and Materials (ASTM) Standard Practice for Environmental Site Assessments: Phase I Environmental Site Assessment Process, ASTM Designation E1527-013 (ASTM E1527), recognized environmental conditions that may have occurred, or otherwise manifested themselves, subsequent to the completion of the 2020 Phase I ESA. The Phase I ESA Update should be read in conjunction with the 2020 Phase I ESA.
SCOPE OF WORK
This Phase I ESA Update has been prepared in accordance with the scope of work in the following:
• ASTM E1527; and
• Email correspondence dated October 4, 2021, between Farallon and SteelWave related to the Phase I ESA Update.
There were no exceptions to, or deletions from, ASTM E1527-13. A limiting condition encountered during the completion of the 2020 Phase I ESA was the presence of vehicles parked 1 Phase I Environmental Site Assessment Report, 170 through 192 El Camino Real, South San Francisco, California dated December 14, 2020, prepared by Farallon.
SteelWave Acquisitions, LLC
October 21, 2021
P:\2516 SteelWave Acquisitions\2516002 180 El Camino Real SSF\Deliverables\2021 Phase I ESA Udpate\2021-10 Phase I ESA Update Ltr.doc Your Challenges. Our Priority. | farallonconsulting.com on the Site that prevented Farallon from observing the entire ground surface of the Site. This limiting condition is not expected to hinder the conclusions of this Phase I ESA Update.
REVIEW OF 2020 PHASE I ESA
The 2020 Phase I ESA documented that the Site contains remnants of former shopping center retail businesses and a former gasoline service station and auto repair facility. The shell of the shopping center’s main building, totaling approximately 140,000 square feet, remains standing.
The Site is currently surrounded by a perimeter fence to prevent unlawful access. Sidewalks border the Site to the northwest and southwest, and a concrete retaining wall partially borders the southeastern boundary of the Site. Remaining areas of the Site consist of asphalt-paved parking and landscaped areas. Access to the Site is gained from Huntington Avenue, northeast of the Site; El Camino Real, southwest of the Site; and South Spruce Avenue, northwest of the Site.
The Site building shell currently occupies the eastern portion of the Site and was a former commercial and retail building previously divided into four suites. At the time of the Site visit, the interior portions of the building were generally demolished, leaving the main exterior walls, roof, and floor; most other features and divisions were removed. The remainder of the Site consists of asphalt-paved parking and minimal landscaping. Stockpiles of construction materials such as iron beams and heavy equipment observed in the December 2020 Site visit had been moved or removed from the Site as of the site reconnaissance on October 11, 2021.
A former gasoline service station and automotive repair facility was present on the northwestern corner of the Site near the intersection of El Camino Real and South Spruce Avenue. All former associated buildings have been removed and the area is currently open ground. Monitoring well covers, presumed to be soil vapor monitoring wells, were observed at this location.
Based on review of the Site history, reconnaissance of the Site, and review of regulatory agency lists, this Phase I ESA Update identified the following recognized environmental condition in connection with the Site:
• The release of hazardous substances or petroleum products in connection with historical operations at the former gasoline service station and automotive repair facility on the northwestern portion of the Site.
The above-noted recognized environmental condition is currently being overseen by the San Mateo County Environmental Health Groundwater Protection Program and includes ongoing remedial efforts. Additional records reviewed indicate an Environmental Agreement between Chevron Environmental Management Company (EMC) and Shamaim, Inc. (the Site owner), where EMC agrees to conduct certain remedial work on the impacted property over a certain time period. As of the date of the 2020 Phase I ESA, the former gasoline service station had not received regulatory closure for historical releases.
SteelWave Acquisitions, LLC
October 21, 2021
P:\2516 SteelWave Acquisitions\2516002 180 El Camino Real SSF\Deliverables\2021 Phase I ESA Udpate\2021-10 Phase I ESA Update Ltr.doc Your Challenges. Our Priority. | farallonconsulting.com
SITE RECONNAISSANCE
Martin Hamann of Farallon conducted a site reconnaissance as part of the Phase I ESA Update on October 11, 2021. Weather conditions during the site reconnaissance were clear, with ambient daytime air temperatures of approximately 70 degrees Fahrenheit. No Site access restrictions were encountered during the site reconnaissance.
The observations made during the site reconnaissance conducted for the Phase I ESA Update were consistent with the observations made during the 2020 Phase I ESA reconnaissance, and there were very few changes to site activities relative to the 2020 Phase I ESA. Farallon did observe the presence of five roll-off bins located on the northeastern portion of the property.
Four of the roll-off bins were inside plastic secondary containment structures. The bins appeared to be filled with silty material. The roll of bins had “Non-Hazardous Waste” labels indicating the contents were slurry and the generator was identified as PG&E. The Site security person, Yoshi Hearn, indicated that Pacific Gas and Electric used that portion of the Site to temporarily store that waste before disposal. There were no indications that any of the waste had leaked from the roll-off bins; however, some of the bin’s secondary containment appeared to need attention. This information was brought to Yoshi Hearn’s attention, who indicated he will direct Pacific Gas and Electric to correct the issue. A 5-gallon drum of presumed waste oil was observed in the parking lot adjacent to two large tires. There were indications of minor oil staining in the area, but this is viewed as a de minimis condition requiring proper disposal and handling but not having a material impact on the findings of this report.
There were no changes observed in the adjacent property uses at the time of the site reconnaissance completed for the Phase I ESA Update. Photographs taken during the site reconnaissance are shown in Attachment B.
INTERVIEWS
Farallon conducted interviews with individuals familiar with the Site and contacted relevant local governmental agencies to obtain additional Site information. The responses from the parties contacted are provided below.
INTERVIEW WITH SITE REPRESENTATIVE
Farallon was not provided with a Site representative to interview, which represents a data gap.
However, because changes to the Site use and layout during known commercial periods are well documented, and environmental investigations have been conducted at the Site and surrounding areas, this data gap is not considered significant and is not expected to hinder the conclusions of this report.
INTERVIEW WITH FIRE DEPARTMENT
Farallon contacted the South San Francisco Fire Department on October 7, 2021, regarding records related to previous and current aboveground storage tanks (ASTs) and underground SteelWave Acquisitions, LLC
October 21, 2021
Your Challenges. Our Priority. | farallonconsulting.com storage tanks (USTs) at the Site. No response from the South San Francisco Fire Department was received prior to completion of this Phase I ESA Update, which represents a data gap. However, because changes to the Site use and layout during known commercial periods are well documented and environmental investigations have been conducted at the Site and surrounding areas, this data gap is not considered significant and is not expected to hinder the conclusions of this report.
INTERVIEW WITH CITY OF SAN FRANCISCO OFFICE OF THE CITY CLERK Farallon contacted the City of South San Francisco Office of the City Clerk on October 7, 2021, regarding previous and current ASTs and USTs at the Site. No response from the City of South San Francisco Office of the City Clerk was received prior to completion of this Phase I ESA Update, which represents a data gap. However, the City of South San Francisco Office of the City Clerk previously indicated it had no records to provide. Changes to the Site use and layout during known commercial periods are well documented and environmental investigations have been conducted at the Site and surrounding areas, so this data gap is not considered significant and is not expected to hinder the conclusions of this report.
INTERVIEW WITH SAN MATEO COUNTY ENVIRONMENTAL HEALTH
Farallon contacted San Mateo County Environmental Health on October 7, 2021, regarding previous and current ASTs and USTs at the Site. No files from San Mateo County Environmental Health had been received prior to completion of this Phase I ESA Update, which represents a data gap. However, because changes to the Site use and layout during known commercial periods are well documented and environmental investigations have been conducted on the Site and surrounding areas, this data gap is not considered significant and is not expected to hinder the conclusions of this report.
REGULATORY REVIEW
Farallon commissioned an Environmental Data Resources, Inc. (EDR) regulatory database search to identify reported environmental issues related to the Site and facilities in the Site vicinity. Farallon used the greater of each approximate minimum search distance from the Site for each of the referenced federal and state environmental databases, as specified in ASTM E1527-13.
Farallon reviewed the results from the earlier Environmental Risk Information Services (ERIS) Database Report prepared for the Site dated May 14, 2021 (ERIS Report) to note reported facilities in the vicinity of the Site that were considered to have a potential to adversely impact the Site (i.e., are known to have resulted in or are expected to result in a recognized environmental condition). Reported facilities identified in the ERIS Report were evaluated with respect to the nature and extent of a given release, the distance of the reported facility from the Site, the stratigraphy of soils, the expected soil permeability, and the topographic position of a reported facility with respect to known or expected local and/or regional groundwater flow direction.
P:\2516 SteelWave Acquisitions\2516002 180 El Camino Real SSF\Deliverables\2021 Phase I ESA Udpate\2021-10 Phase I ESA Update Ltr.doc SteelWave Acquisitions, LLC
October 21, 2021
P:\2516 SteelWave Acquisitions\2516002 180 El Camino Real SSF\Deliverables\2021 Phase I ESA Udpate\2021-10 Phase I ESA Update Ltr.doc Your Challenges. Our Priority. | farallonconsulting.com The descriptions of the databases searched, the complete database names for the abbreviations, and the associated search distances from the Site are provided in the EDR Report presented in Attachment C.
The listings in the 2021 EDR Report are consistent with the May 2021 ERIS database listings and those discussed in the 2020 Phase I ESA, and there are no changes in the EDR Report that materially impact the findings of this Phase I ESA Update.
USER-PROVIDED INFORMATION
Farallon understands that the user of this Phase I ESA Update, SteelWave, is seeking to follow the standards set forth in ASTM E1527-13 to complete an environmental assessment of the Site.
The user has specific responsibilities for fulfilling ASTM E1527-13 requirements to help identify the possibility of recognized environmental conditions in connection with the Site. These responsibilities do not require the technical expertise of an Environmental Professional and were not performed by the Environmental Professional who conducted the Phase I ESA at the Site.
To facilitate fulfillment of the ASTM E1527-13 requirements identified below, Farallon provided SteelWave with a copy of the Phase I ESA User Questionnaire (User Questionnaire) to complete. No response to the User Questionnaire was received prior to completion of this Phase I ESA Update, which is considered a data gap. However, because changes to the Site use and layout during known industrial periods are well documented and environmental investigations have been conducted at the Site and surrounding areas, this data gap is not considered significant and is not expected to hinder the conclusions of this report.
PREVIOUS ENVIRONMENTAL STUDIES
As part of the 2020 Phase I ESA, SteelWave provided Farallon with previous environmental studies prepared for the former gasoline service station and automotive repair facility on the Site.
Additionally, Farallon searched the California State Water Resources Control Board online GeoTracker database (GeoTracker database) and the California Department of Toxic Substances Control online EnviroStor database (EnviroStor database) for records related to the Site. These records dated back to 2005 and included groundwater monitoring reports, site investigation reports, remedial action plans, and requests for closure. Farallon reviewed pertinent environmental studies related to the former gasoline service station and automotive repair facility on the Site and summarized its findings in the 2020 Phase I ESA Report.
The 2020 Phase I ESA Report also included an Environmental Agreement (Agreement) dated September 8, 2017, entered into by and between EMC, for itself and as attorney-in-fact for Union Oil Company of California, and Shamaim, Inc. The Agreement indicates that EMC would pay for the implementation of a Revised Remedial Action Plan and other environmental costs within a specified time period. A copy of the Agreement is included as Appendix C of the 2020 Phase I ESA Report.
SteelWave Acquisitions, LLC
October 21, 2021
P:\2516 SteelWave Acquisitions\2516002 180 El Camino Real SSF\Deliverables\2021 Phase I ESA Udpate\2021-10 Phase I ESA Update Ltr.doc Your Challenges. Our Priority. | farallonconsulting.com Farallon reviewed the GeoTracker and EnviroStor databases on October 5, 2021 to evaluate whether additional information was available on the Site after the 2020 Phase I ESA Report. An email dated January 15, 2021 was present in the GeoTracker database from the San Mateo County Groundwater Protection Program (the regulatory agency overseeing the above-described cleanup) to EMC’s consultant. This email indicated that the San Mateo County Groundwater Protection Program was waiting for additional information from the consultant regarding future mitigation options. Farallon spoke with the case officer at the San Mateo County Groundwater Protection Program on May 18, 2021, who confirmed that no additional information or data beyond what was placed in the GeoTracker database had been received. A second email from the case officer at the San Mateo County Groundwater Protection Program on September 22, 2021, indicated that San Mateo County Groundwater Protection Program concurs with the approach to move the case toward low-threat closure and directed the submittal of a revised pilot test work plan and site management plan no later than January 21, 2022 (which had not been submitted at the time of this Phase I ESA Update).
CONCLUSIONS
Farallon has performed a Phase I ESA Update in conformance with the scope and limitations of ASTM E1527-13 for the property located at 170 through 192 El Camino Real, South San Francisco, California. There were no exceptions to or deletions from ASTM E1527-13. This assessment has revealed no evidence of recognized environmental conditions in connection with the Site beyond the recognized environmental condition noted in the 2020 Phase I ESA Report, which stated:
Based on review of the Site history, reconnaissance of the Site, and review of regulatory agency lists, this Phase I ESA identified the following recognized environmental condition in connection with the Site:
• The release of hazardous substances or petroleum products in connection with historical operations at the former gasoline service station and automotive repair facility on the northwestern portion of the Site.
This recognized environmental condition is currently being overseen by the San Mateo County Environmental Health Groundwater Protection Program and includes ongoing remedial efforts. Additional records reviewed indicate an Environmental Agreement between Chevron Environmental Management Company and Shamaim, Inc., where Chevron Environmental Management Company agrees to conduct certain remedial work on the impacted property over a certain time period. As of the date of this report, the former gasoline service station has not received regulatory closure for historical releases.
SteelWave Acquisitions, LLC
October 21, 2021
P:\2516 SteelWave Acquisitions\2516002 180 El Camino Real SSF\Deliverables\2021 Phase I ESA Udpate\2021-10 Phase I ESA Update Ltr.doc Your Challenges. Our Priority. | farallonconsulting.com
STATEMENT OF LIMITATIONS
LIMITATIONS
General Limitations
The conclusions contained in this report/assessment are based on professional opinions with regard to the subject matter. These opinions have been arrived at in accordance with currently accepted hydrogeologic and engineering standards and practices applicable to this location. The conclusions contained herein are subject to the following inherent limitations:
• Accuracy of Information. Farallon obtained, reviewed, and evaluated certain information used in this report/assessment from sources that were believed to be reliable.
Farallon’s conclusions, opinions, and recommendations are based in part on such information. Farallon’s services did not include verification of its accuracy or authenticity. Should the information upon which Farallon relied prove to be inaccurate or unreliable, Farallon reserves the right to amend or revise its conclusions, opinions, and/or recommendations.
• Reconnaissance and/or Characterization. Farallon performed a reconnaissance and/or characterization of the Site that is the subject of this report/assessment to document current conditions. Farallon focused on areas deemed more likely to exhibit hazardous materials conditions. Contamination may exist in other areas of the Site that were not investigated or were inaccessible. Site activities beyond Farallon’s control could change at any time after the completion of this report/assessment.
For the foregoing reasons, Farallon cannot and does not warrant or guarantee that the Site is free of hazardous or potentially hazardous substances or conditions, or that latent or undiscovered conditions will not become evident in the future. Farallon’s observations, findings, and opinions can be considered valid only as of the date of this report.
This report/assessment has been prepared in accordance with the contract for services between Farallon and SteelWave Acquisitions, LLC, and currently accepted industry standards. No other warranties, representations, or certifications are made.
Limitation on Reliance by Third Parties
Reliance by third parties is prohibited. This report/assessment has been prepared for the exclusive use of SteelWave at the Site at a specific point in time. USAA Real Estate Co. (USAA) may also rely on this Phase I ESA Update, subject to the following conditions:
• USAA is subject to the same limitations and conditions as SteelWave as stated in the contracts for services between Farallon and SteelWave dated December 3, 2020 and October 8, 2021. USAA may be bound by any provision of any agreement related to the Report Update that limits Farallon’s liability to an amount less than $1,000,000 per occurrence, jointly and collectively with any others who are entitled to rely on the Report SteelWave Acquisitions, LLC
October 21, 2021
P:\2516 SteelWave Acquisitions\2516002 180 El Camino Real SSF\Deliverables\2021 Phase I ESA Udpate\2021-10 Phase I ESA Update Ltr.doc Your Challenges. Our Priority. | farallonconsulting.com Update, such that at no time will Farallon’s total liability to relying parties exceed $1,000,000.
• SteelWave and USAA jointly and severally waive and hold Farallon harmless for any and all conflicts interest inherent in a grant of reliance to a potential purchaser from a seller. • Farallon states that the investigation summarized in the Report Update was conducted by Environmental Professionals with the specific education, training, and experience to qualify them to assess a property of the nature, history, and setting of the Site. Farallon states and SteelWave acknowledges that the Report Update was performed in accordance with ASTM E1527-13 Standards, and constitutes a U.S. Environmental Protection Agency All Appropriate Inquiry into the environmental condition of the property. • Farallon disclaims any responsibility for any change of site conditions subsequent to the effective date of the Report Update referenced above.
Subject to the foregoing, no further reliance is authorized by Farallon. Farallon’s consent to rely on the Report Update referenced above does not grant the right to any other third parties. The use of or reliance on the Report Update by SteelWave constitutes its acceptance of the conditions set forth above. Any unauthorized use, interpretation, or reliance on this report/assessment is at the sole risk of that party, and Farallon will have no liability for such unauthorized use, interpretation, or reliance.
Farallon appreciates the opportunity to assist you with this project. Please feel free to contact Martin Hamann at (510) 879-6805 or Richard Makdisi at (510) 879-6801 if you have questions or need additional information.
Sincerely,
Farallon Consulting, L.L.C.
Martin Hamann, P.G., L.G.
Principal Geologist
Richard Makdisi. P.G.
Principal Geochemist
Attachments: Attachment A, Phase I Environmental Site Assessment Report, 170 through 192 El Camino Real, South San Francisco, California
Attachment B, Site Photographs
Attachment C, EDR Report
MH/RM:eh
ATTACHMENT A
PHASE I ENVIRONMENTAL SITE ASSESSMENT REPORT,
170 THROUGH 192 EL CAMINO REAL,
SOUTH SAN FRANCISCO, CALIFORNIA
PHASE I ENVIRONMENTAL SITE ASSESSMENT UPDATE
170 through 192 El Camino Real
South San Francisco, California
Farallon PN: 2516-002
Washing ton
Is saquah | Bellingham | Seat tle
Oregon
Portland | Baker Ci ty
Cali fornia
Oakland | Folsom | Irvine
Q u a li t y S er v i c e f o r E n v i r o nm e n t a l So l u t i o n s | f a r a ll o n c o n s ul t i n g . c om
PHASE I
ENVIRONMENTAL SITE ASSESSMENT REPORT
170 through 192 El Camino Real
South San Francisco, California
Submitted by:
Farallon Consulting, L.L.C.
220 Franklin Street, Suite 300
Oakland, California 94607
Farallon PN: 2516-002
For:
SteelWave Acquisitions, LLC
101 California Street, Suite 800
San Francisco, California 94111
December 14, 2020
Prepared by:
Martin E. Hamann, P.G.
Principal Geologist
Reviewed by:
Richard Makdisi, P.G.
Principal Geochemist
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TABLE OF CONTENTS
ENVIRONMENTAL PROFESSIONALS’ STATEMENT ......................................... iii EXECUTIVE SUMMARY ............................................................................................. iv
1.0 INTRODUCTION.............................................................................................. 1-1 PROJECT AUTHORIZATION............................................................... 1-1 PROFESSIONAL QUALIFICATIONS.................................................. 1-1 PROJECT PURPOSE AND OBJECTIVE.............................................. 1-1 PROJECT SCOPE OF SERVICES ......................................................... 1-2 DEVIATIONS ......................................................................................... 1-2 LIMITING CONDITIONS...................................................................... 1-2 DATA GAPS ........................................................................................... 1-3
2.0 SITE OVERVIEW............................................................................................. 2-1 SITE LOCATION.................................................................................... 2-1 SITE DESCRIPTION.............................................................................. 2-1 SITE OPERATIONS ............................................................................... 2-2 ADJACENT AND SURROUNDING LAND USE ................................ 2-2
3.0 PHYSICAL SETTING...................................................................................... 3-1 TOPOGRAPHY....................................................................................... 3-1 GEOLOGY AND HYDROGEOLOGY.................................................. 3-1 OIL AND GAS RECORDS..................................................................... 3-1 SENSITIVE RECEPTORS...................................................................... 3-2
4.0 USER-PROVIDED INFORMATION ............................................................. 4-1
PHASE I ENVIRONMENTAL SITE ASSESSMENT REPORT
USERS ..................................................................................................... 4-1 PREVIOUS ENVIRONMENTAL STUDIES......................................... 4-1 Environmental Agreement........................................................... 4-4
5.0 SITE BACKGROUND AND HISTORY......................................................... 5-1 SITE......................................................................................................... 5-1 ADJACENT PROPERTIES .................................................................... 5-2
6.0 REGULATORY REVIEW ............................................................................... 6-1 ON-SITE LISTINGS ............................................................................... 6-1 ADJACENT AND OTHER FACILITY LISTINGS............................... 6-2 UNMAPPABLE LISTINGS.................................................................... 6-3
7.0 INTERVIEWS.................................................................................................... 7-1 INTERVIEW WITH SITE REPRESENTATIVE................................... 7-1 INTERVIEW WITH FIRE DEPARTMENT .......................................... 7-1 ii
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INTERVIEW WITH CITY OF SAN FRANCISCO OFFICE OF THE
CITY CLERK.......................................................................................... 7-1
INTERVIEW WITH SAN MATEO COUNTY ENVIRONMENTAL
HEALTH.................................................................................................. 7-1
8.0 SITE RECONNAISSANCE.............................................................................. 8-1 SITE RECONNAISSANCE METHODOLOGY.................................... 8-1 SITE RECONNAISSANCE OBSERVATIONS..................................... 8-1 Interior Observations ................................................................... 8-1 Exterior Observations.................................................................. 8-1 Exterior Observation Comments.................................................. 8-2
9.0 FINDINGS AND OPINIONS............................................................................ 9-1
10.0 CONCLUSIONS .............................................................................................. 10-1
11.0 REFERENCES................................................................................................. 11-1
12.0 LIMITATIONS.............................................................................................. 12-31 GENERAL LIMITATIONS ................................................................ 12-31 LIMITATION ON RELIANCE BY THIRD PARTIES ..................... 12-31
FIGURES
Figure 1 Site Vicinity Map
Figure 2 Site Plan
APPENDICES
Appendix A Professional Qualifications
Appendix B Site Photographs
Appendix C Supporting Environmental Documents
Appendix D ERIS Documents
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We declare that, to the best of our professional knowledge and belief, we meet the definition of Environmental Professional as established in Part 312.10 of Title 40 of the Code of Federal Regulations (40 CFR 312.10) and we have the specific qualifications based on education, training, and experience to assess a property of the nature, history, and setting of the subject property. We have developed and performed all appropriate inquiries in conformance with the standards and practices set forth in 40 CFR 312.
Name Martin E. Hamann, P.G. Name Richard Makdisi, P.G.
Title Principal Geologist Title Principal Geochemist
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EXECUTIVE SUMMARY
Farallon Consulting, L.L.C. (Farallon) has prepared this Phase I Environmental Site Assessment (Phase I ESA) Report for the properties located at 170 through 192 El Camino Real in South San Francisco, California (herein referred to as the Site). The Phase I ESA was conducted by Mr.
Martin Hamann and was reviewed and approved by Mr. Richard Makdisi. Both are experienced Environmental Professionals in the field of Phase I ESAs and related environmental investigations.
This Phase I ESA Report was prepared for SteelWave Acquisitions, LLC in accordance with the letter regarding Proposal for Phase I Environmental Site Assessment, 180 El Camino Real, South San Francisco, California, dated November 10, 2020, from Martin Hamann and Richard Makdisi of Farallon to Bridget Metz of SteelWave Acquisitions, LLC. The scope of work for this Phase I ESA is consistent with ASTM International Standard E1527-13, Standard Practice for Environmental Site Assessments: Phase I Environmental Site Assessment Process (ASTM E1527- 13). ASTM E1527-13 is intended to assist the user in satisfying one of the requirements to qualify for protection from potential liability under the Comprehensive Environmental Response, Compensation, and Liability Act as the innocent landowner, contiguous property owner, or bona fide prospective purchaser. ASTM E1527-13 constitutes “all appropriate inquiry” into the previous ownership, uses, and environmental conditions of a property consistent with good commercial or customary practice, as defined in Section 9601(35)(B) of Title 42 of the U.S. Code.
There were no deviations from ASTM E1527-13 during this Phase I ESA. No limiting conditions were encountered during this Phase I ESA.
Farallon did not receive a response to the Phase I ESA User Questionnaire by a Site representative and no response was received from city and county agencies regarding the Site prior to completion of this Phase I ESA Report, which are considered data gaps. Farallon also was not provided a Site representative to interview. However, because changes to the Site use and layout during known commercial periods are well documented and environmental investigations have been conducted at the Site and surrounding areas, these data gaps are not considered significant and are not expected to impact the conclusions of this report.
The purpose of the Phase I ESA was to identify, as practicable, recognized environmental conditions on the Site or proximate to the Site that have caused and/or may cause an adverse environmental condition. This Phase I ESA Report provides the results of investigation into past and present ownership and uses of the Site, consistent with good commercial and/or customary practice.
The Site consists of San Mateo County Assessor’s Parcel No. 014-183-110, which totals approximately 14.5 acres of land. The Site contains remnants of former shopping center retail businesses and a former gasoline service station and auto repair facility. The shell of the shopping center’s main building, which totals approximately 140,000 square feet, remains standing. The Site is currently surrounded by a perimeter fence to prevent unlawful access. Remaining areas of the Site consist of asphalt-paved parking and landscaped areas. Access to the Site is gained from v
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At the time of the site reconnaissance, Farallon did not observe evidence of releases on or around the Site building or associated parking areas. Farallon did not observe evidence of spills or releases on adjacent properties during the site reconnaissance.
The earliest records for the Site, topographic maps from 1896 through 1939, showed that the Site was undeveloped until approximately the 1930s. The aerial photograph from 1930 showed what appeared to be a farmhouse or other small structure in the center of the Site; the remaining portions of the Site appeared to be agricultural fields.
The 1946 aerial photograph shows what appears to be military-style barracks or some other rudimentary housing along the southern and eastern portions of the Site. Reportedly, prior to current development of the Site, which occurred in the mid-1960s, the Site was part of the Tanforan horse racetrack, southeast of the Site. The Site was not on the track itself, but on the northwestern portion of the Tanforan racetrack property. In 1911, the Tanforan racetrack was reportedly turned into a military training site until the end of World War I, when the property returned to use as a horse racetrack. In 1942, the entire Tanforan property was temporarily used by the U.S. Army as an assembly center for people of Japanese ancestry. Approximately 8,000 Japanese persons were reportedly processed at this location. Between 1943 and 1946, the property was occupied by the U.S. Navy for troop housing and returned to use as a racetrack after 1946.
The 1968 aerial photograph showed a gasoline service station and automotive repair facility along with the large multi-tenant retail space.1 Environmental investigations at the Site were initiated in April 1992 when three gasoline underground storage tanks (USTs) associated with the gasoline service station were removed and subsequently found to have leaked. Various monitoring and remedial actions were performed by the responsible party and by mid- to late 2016, the removal of the automotive repair facility had been completed.
SteelWave Acquisitions, LLC provided Farallon with previous environmental studies prepared for the former gasoline service station and automotive repair facility on the Site. Additionally, Farallon searched the California State Water Resources Control Board online GeoTracker database and the California Department of Toxic Substances Control online EnviroStor database for records related to the Site. These records dated back to 2005 and included groundwater monitoring reports, site investigation reports, remedial action plans, and requests for closure. Farallon reviewed pertinent environmental studies related to the former gasoline service station and automotive repair facility on Site. As recently as January 2020, environmental regulators required a work plan to perform vapor extraction that targets residual sorbed mass from the soil and/or a vapor mitigation and monitoring plan for the future buildings potentially impacted by soil vapor. The San Mateo County 1 Records intermix the names and addresses of the gasoline service station and automotive repair facility. The addresses include 180 El Camino Real, 190 El Camino Real, and 192 El Camino Real. The names used to represent the businesses at these locations include Firestone #3654, Firestone Complete Auto Care #3654, 1X Firestone Stores #3654, 1X Union Oil Stn #6980, Firestone Tire and Service, Tesoro Gasoline Marketing Co, Unocal Service Station #6980, Bridgestone Retail Operations LLC, and Union Oil (also called Unocal) Service Station #6980. vi
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Farallon was provided an Environmental Agreement (Agreement) dated September 8, 2017, entered into by and between Chevron Environmental Management Company (EMC), for itself and as attorney-in-fact for Union Oil Company of California, and Shamaim, Inc. (the Site owner). The Agreement indicates that EMC would pay for the implementation of a Revised Remedial Action Plan and other environmental costs within a specified time period. As of the date of this report, the former gasoline service station has not received regulatory closure for historical releases.
Based on review of reasonably ascertainable information, the release of hazardous substances or petroleum products in connection with historical operations at the former gasoline service station and automotive repair facility on the northwestern portion of the Site represents a recognized environmental condition in connection with the Site.
Adjacent properties at the time of Farallon’s site reconnaissance included offices and commercial properties to the northeast, a movie theater and retail shopping center to the southeast and south, El Camino Real followed by residential and commercial properties to the southwest, and South Spruce Avenue followed by a manufacturing plant to the northwest.
Adjacent properties appeared relatively undeveloped, with the exception of the Tanforan racetrack, until the mid-1940s, when presumed military barracks were constructed on and adjacent to the Site and residential development commenced southwest of the Site. In subsequent years, more infill and localized development surrounding the Site occurred.
The Environmental Risk Information Services (ERIS) Database Report prepared for the Site dated November 16, 2020 (ERIS Report) identified the Site address in several databases. The identification of the Site in the databases is attributed to historical activities such as waste management, waste reporting, etc., at the commercial retail portions of the Site (grocery stores, pharmacies, etc.), along with chemical uses and releases associated with the former gasoline service station and automotive repair facility on the northwestern portion of the Site. Other than the documented releases associated with the former gasoline service station and automotive repair facility, there are no indications that the listings on the databases for the other portions of the Site indicate a release or threatened release that would represent a recognized environmental condition in connection with the Site.
The ERIS Report identified several facilities adjacent to the Site in the regulatory databases. Based on the information reviewed and the inferred directions of potential contaminant migration, these adjacent facilities are not considered to represent a recognized environmental condition in connection with the Site.
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• The release of hazardous substances or petroleum products in connection with historical operations at the former gasoline service station and automotive repair facility on the northwestern portion of the Site.
This recognized environmental condition is currently being overseen by the San Mateo County Environmental Health Groundwater Protection Program and includes ongoing remedial efforts.
Additional records reviewed indicate an Environmental Agreement between Chevron Environmental Management Company and Shamaim, Inc., where Chevron Environmental Management Company agrees to conduct certain remedial work on the impacted property over a certain time period. As of the date of this report, the former gasoline service station has not received regulatory closure for historical releases.
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1.0 INTRODUCTION
This Phase I Environmental Site Assessment (Phase I ESA) Report was prepared by Farallon Consulting, L.L.C. (Farallon) of the properties at 170 through 192 El Camino Real in South San Francisco, California (herein referred to as the Site) (Figure 1). This section discusses the project authorization, and the qualifications of the Environmental Professionals conducting and reviewing the Phase I ESA work. Also included in this section are the project purpose, objective, scope of services, deviations, limiting conditions, and data gaps.
PROJECT AUTHORIZATION
This Phase I ESA Report was prepared for SteelWave Acquisitions, LLC in accordance with the letter regarding Proposal for Phase I Environmental Site Assessment, 180 El Camino Real, South San Francisco, California, dated November 10, 2020, from Martin Hamann and Richard Makdisi of Farallon to Bridget Metz of SteelWave Acquisitions, LLC. The scope of work for this Phase I ESA is consistent with ASTM International Standard E1527-13, Standard Practice for Environmental Site Assessments: Phase I Environmental Site Assessment Process (ASTM E1527- 13).
PROFESSIONAL QUALIFICATIONS
The Phase I ESA was conducted by Martin Hamann and was reviewed and approved by Richard Makdisi. Both have an understanding of surface and subsurface environmental conditions and the processes used to evaluate these conditions, and the ability to develop opinions regarding conditions indicative of a release or threatened release of hazardous substances and petroleum products. These Environmental Professionals have developed and performed all appropriate inquiry, in conformance with the standards and practices set forth in Part 312 of Title 40 of the Code of Federal Regulations. The professional qualifications of Martin Hamann and Richard Makdisi are provided in Appendix A.
PROJECT PURPOSE AND OBJECTIVE
The purpose of the Phase I ESA was to identify, as practicable, recognized environmental conditions on the Site and within the appropriate study area that have caused and/or may cause an adverse environmental impact. ASTM E1527-13 is intended to permit a user to satisfy one of the requirements to qualify for protection from potential liability under the Comprehensive Environmental Response, Compensation, and Liability Act as the innocent landowner, contiguous property owner, or bona fide prospective purchaser. ASTM E1527-13 constitutes “all appropriate inquiry” into the previous ownership, uses, and environmental conditions of a property consistent with good commercial or customary practice, as defined in Section 9601(35)(B) of Title 42 of the U.S. Code.
The objective of the Phase I ESA was to perform an appropriate inquiry into past and present ownership and uses of the Site, consistent with good commercial and/or customary practice. This 1-2
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For the purpose of this Phase I ESA Report, the term “recognized environmental condition” is defined as the presence or likely presence of any hazardous substance or petroleum product in, on, or at the Site due to releases to the environment, under conditions indicative of a release to the environment, or under conditions that pose a material threat of a future release to the environment.
The term is not intended to include “de minimis conditions” that generally do not present a threat to human health or the environment and that generally would not be the subject of an enforcement action if brought to the attention of the applicable governmental agencies.
The term “controlled recognized environmental condition” is defined as a recognized environmental condition resulting from a past release of a hazardous substance or petroleum product that has been addressed to the satisfaction of the applicable regulatory authority, with hazardous substances or petroleum products allowed to remain in-place subject to implementation of required controls.
The term “historical recognized environmental condition” is defined as a past release of any hazardous substance or petroleum product that has occurred in connection with the Site and has been addressed to the satisfaction of the applicable regulatory authority, without subjecting the Site to any required controls.
PROJECT SCOPE OF SERVICES
This Phase I ESA Report was prepared for SteelWave Acquisitions, LLC in accordance with the letter regarding Proposal for Phase I Environmental Site Assessment, 180 El Camino Real, South San Francisco, California, dated November 10, 2020, from Martin Hamann and Richard Makdisi of Farallon to Bridget Metz of SteelWave Acquisitions, LLC. The scope of work for this Phase I ESA report included a records review, literature research and review, a site reconnaissance, interviews with individuals familiar with the Site, interviews with local governmental officials, and preparation of this report.
DEVIATIONS
There were no deviations from ASTM E1527-13 during this Phase I ESA.
LIMITING CONDITIONS
No limiting conditions were encountered during this Phase I ESA. 1-3
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DATA GAPS
Data gaps may affect the ability to identify recognized environmental conditions and Farallon’s ability to render opinions and conclusions for presentation in the Phase I ESA Report. The following data gaps were identified in connection with this Phase I ESA Report:
• Farallon requested records from the South San Francisco Fire Department and San Mateo County Environmental Health related to environmental records for the Site. No response was received from the South San Francisco Fire Department or San Mateo County Environmental Health prior to completion of this Phase I ESA Report. Farallon also was not provided a Site representative to interview. However, because changes to the Site use and layout during known commercial periods are documented and environmental investigations have been conducted at the Site and surrounding areas, this data gap is not considered significant and is not expected to hinder the conclusions of this report. • Farallon provided SteelWave Acquisitions, LLC with a copy of the Phase I ESA User Questionnaire (User Questionnaire) to complete. No response to the User Questionnaire was received prior to completion of this Phase I ESA Report, which is considered a data gap. However, because changes to the Site use and layout during known commercial periods are documented and environmental investigations have been conducted at the Site and surrounding areas, this data gap is not considered significant and is not expected to hinder the conclusions of this report.
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2.0 SITE OVERVIEW
This section includes an overview of the Site location, improvements, and operations.
A description of adjacent and surrounding land use also is provided.
SITE LOCATION
The Site is located in South San Francisco, San Mateo County, California and generally bounded by Huntington Avenue to the northeast, El Camino Real to the southwest, and South Spruce Avenue to the northwest. The location is in a mixed-use commercial and residential area. The Site vicinity is shown on Figure 1.
SITE DESCRIPTION
The Site consists of San Mateo County Assessor’s Parcel No. 014-183-110, which totals approximately 14.5 acres of land. The Site contains remnants of former shopping center retail businesses and a former gasoline service station and auto repair facility. The shell of the shopping center’s main building, which totals approximately 140,000 square feet, remains standing. The Site is currently surrounded by a perimeter fence to prevent unlawful access. Sidewalks border the Site to the northwest and southwest and a concrete retaining wall partially borders the southeastern boundary of the Site. Remaining areas of the Site consist of asphalt-paved parking and landscaped areas. Access to the Site is gained from Huntington Avenue, northeast of the Site, El Camino Real, southwest of the Site, and South Spruce Avenue, northwest of the Site.
The Site building shell occupies the eastern portion of the Site and was a former commercial/retail building previously divided into four suites. At the time of the Site visit, the interior portions of the building were being demolished, leaving the main exterior walls, roof, and floor, but most other features and divisions were being removed. The remainder of the Site consists of asphalt-paved parking and minimal landscaping. Stockpiles of construction materials such as iron beams, heavy equipment, etc. are currently stored on the Site.
A former gasoline service station and automotive repair facility was present on the northwestern corner of the Site near the intersection of El Camino Real and South Spruce Avenue. 2 Associated
buildings have been removed and the area is currently open ground. Monitoring well covers, presumed to be soil vapor monitoring wells, were observed at this location. 2 This portion of the Site has historically contained a gasoline service station and an automotive repair facility.
Records intermix the names and addresses of the gasoline service station and automotive repair facility. The addresses at this location include 180 El Camino Real, 190 El Camino Real, and 192 El Camino Real. The names used to represent the businesses at these locations include Firestone #3654, Firestone Complete Auto Care #3654, 1X Firestone Stores #3654, 1X Union Oil Stn #6980, Firestone Tire and Service, Tesoro Gasoline Marketing Co, Unocal Service Station #6980, Bridgestone Retail Operations LLC, and Union Oil (also called Unocal) Service Station #6980.
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SITE OPERATIONS
The Site is vacant and slated for future redevelopment for retail and commercial use. The building previously housed a CVS Pharmacy (formerly Long’s Drugs), Bedroom Express, Safeway, and a Bally’s Gym. The occupants and stores have changed over time as evidenced by the city directory reviewed for the Site, discussed in Section 5.1, Site.
Figure 2 presents a plan map of the Site. Additional details pertaining to the Site are provided in Section 8.2, Site Reconnaissance Observations. Site photographs are presented in Appendix B.
ADJACENT AND SURROUNDING LAND USE
Adjacent properties at the time of Farallon’s site reconnaissance included offices and commercial properties to the northeast, a movie theater and retail shopping center to the southeast and south, El Camino Real followed by residential and commercial properties to the southwest, and South Spruce Avenue followed by a manufacturing plant to the northwest.
Farallon did not access adjacent properties, which were observed from public rights-of-way. No evidence of spills or releases was observed at adjacent properties during the site reconnaissance. 3-1
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3.0 PHYSICAL SETTING
The physical setting of the Site, including topography, geology, and hydrogeology, is described in this section. Farallon’s assessment of sensitive receptors in the area also is discussed.
TOPOGRAPHY
Farallon reviewed the U.S. Geological Survey topographic map for San Francisco South, California dated November 16, 2020 provided by Environmental Risk Information Services (ERIS). The map depicts the Site at an elevation of approximately 41 feet above mean sea level.
The Site topography is relatively flat. Regional topography is generally flat, with a slight slope to the west-northwest.
GEOLOGY AND HYDROGEOLOGY
The Site is located approximately 1 mile south of the base of San Bruno Mountain. Site geology consists of Pleistocene stream channel deposits composed mostly of gray to brown sand and silt, which locally may contain clay, gravel, or boulders. A subsurface stream channel trends toward the northeast beneath Spruce Avenue. The alluvium lies above the surrounding Quaternary Colma Formation, which, in this area, consists of mostly yellowish-orange to gray sandy clay and silty sand. Previous investigations indicated that fill material is present at the Site to approximate depths between 7.5 and 15 feet below ground surface (bgs). Investigations of a former gasoline service station on the Site indicated that soil at the Site consists mainly of fine-grained materials (silt and clay) extending from near ground surface to depths ranging from 7 feet bgs to as deep as 40 ft bgs, underlain by alternating layers of coarse-grained sand/silt, sand/clay, and sand and fine-grained silt/clay.
The Site lies within the Westside Groundwater Basin. Groundwater in the basin has been designated as beneficial for domestic, municipal, and industrial uses and as potentially beneficial for agricultural use.
Groundwater was first encountered within coarse-grained sediments (sand/silty sand) or finegrained materials (sandy silt/silt) in borings advanced at the former gasoline service station on the Site. Static groundwater levels within wells completed with shallower screens have historically ranged from 21.47 to 35.83 feet below the top of the well casing. According to Site data, a perched groundwater-bearing zone has also been identified at a depth of approximately 5 to 11.5 feet bgs.
The direction of groundwater flow has historically been variable; however, it appears to flow generally toward the southwest.
OIL AND GAS RECORDS
According to the California Department of Conservation, Geologic Energy Management Division Well Finder online database, there are no permitted oil or gas wells on the Site or adjacent properties.
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SENSITIVE RECEPTORS
Farallon conducted a limited assessment of sensitive receptors on or in the vicinity of the Site that was confined to visually apparent features such as surface water bodies (e.g., low-lying wet areas, streams, ponds) and residential and recreational areas. Farallon’s assessment of sensitive receptors included a review of readily ascertainable information relating to the presence of private, semiprivate, public, and industrial water supply wells.
According to the ERIS PSR, there is no wetland designation associated with the Site. The Site is not included in a flood zone area. The nearest surface water body, a drainage slough that enters the San Francisco Bay, is approximately 1 mile east of the Site. 4-1
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4.0 USER-PROVIDED INFORMATION
Farallon understands that the user of this report, SteelWave Acquisitions, LLC, is seeking to follow the standards set forth in ASTM E1527-13 to complete an environmental assessment of the Site.
The user has specific responsibilities for fulfilling ASTM E1527-13 requirements to help identify the possibility of recognized environmental conditions in connection with the Site. These responsibilities do not require the technical expertise of an Environmental Professional, and were not performed by the Environmental Professional who conducted the Phase I ESA at the Site.
To facilitate fulfillment of the ASTM E1527-13 requirements identified below, Farallon provided SteelWave Acquisitions, LLC with a copy of the Phase I ESA User Questionnaire (User Questionnaire) to complete. No response to the User Questionnaire was received prior to completion of this Phase I ESA Report, which is considered a data gap. However, because changes to the Site use and layout during known industrial periods are well documented and environmental investigations have been conducted at the Site and surrounding areas, this data gap is not considered significant and is not expected to hinder the conclusions of this report.
PHASE I ENVIRONMENTAL SITE ASSESSMENT REPORT USERS
SteelWave Acquisitions, LLC will rely on this Phase I ESA Report.
PREVIOUS ENVIRONMENTAL STUDIES
SteelWave Acquisitions, LLC provided Farallon with previous environmental studies prepared for the former gasoline service station and automotive repair facility on the Site. Additionally, Farallon searched the California State Water Resources Control Board online GeoTracker database (GeoTracker database) and the California Department of Toxic Substances Control online EnviroStor database (EnviroStor database) for records related to the Site. These records dated back to 2005 and included groundwater monitoring reports, site investigation reports, remedial action plans, and requests for closure. Farallon reviewed pertinent environmental studies related to the former gasoline service station and automotive repair facility on Site.
In April 1992, three gasoline underground storage tanks (USTs) were removed from the former gasoline service station on the northwestern corner of the Site at 180 through 192 El Camino Real.
The USTs were steel-walled 12,000-gallon tanks used to store unleaded gasoline. During removal, no holes or cracks were reportedly observed in the USTs.
During UST removal, multiple soil samples were reportedly collected from the base and sidewalls of the UST excavations and from the base of the product piping trenches. Petroleum hydrocarbons were detected in each set of soil samples. The highest concentrations of total petroleum hydrocarbons (TPH) as gasoline (TPHg) and benzene were detected in the samples from the product piping trenches and the base of the UST excavations.
The dimensions of the initial excavations were not clearly documented, but an estimated 350 cubic yards of soil was reportedly excavated and removed from the Site. Later in 1992, additional 4-2
P:\2516 SteelWave Acquisitions\2516002 180 El Camino Real SSF\Deliverables\2020 Ph I ESA\2020 Ph I ESA Rpt.docx Q u a li t y S e r v i c e f o r E n v i r o nm e n ta l So l u t i o n s | f a r a ll o n c o n s ul t i n g . c om investigation and additional vertical and lateral excavation was performed both in the former UST pit and in the vicinity of product piping and the dispenser island. The maximum depth of the UST pit excavation was estimated at 21 feet bgs and confirmation soil samples were reportedly again collected and analyzed. An additional 350 cubic yards of soil was estimated to have been removed during this phase.
In 1993, three groundwater monitoring wells were reportedly installed to total depths of 60 to 65 feet bgs (MW-1, MW-2, and MW-3). During installation, soil samples were collected and analyzed. Significant petroleum hydrocarbon-related impacts to soil were reportedly encountered to a depth of 40 feet bgs; the most significant impacts were reportedly observed at a depth of 20 feet bgs. Contaminant concentrations detected in soil samples included TPHg up to 120,000 milligrams per kilogram (mg/kg), benzene up to 480 mg/kg, toluene up to 1,000 mg/kg, ethylbenzene up to 1,300 mg/kg, and xylenes up to 8,800 mg/kg.
The maximum constituent concentrations detected in groundwater samples from these wells included TPHg at 55,000 micrograms per liter (μg/L), benzene at 7,300 μg/L, toluene at 9,300 μg/L, ethylbenzene at 2,100 μg/L and xylenes at 12,000 μg/L. Groundwater was also established to flow in a westerly direction with a hydraulic gradient estimated at 0.036 feet per foot.
In 1994, two additional groundwater monitoring wells were installed (MW-5 and MW-6) and routine groundwater monitoring of the monitoring well network reportedly occurred until May 2000. In 2003, groundwater monitoring resumed at the direction of the San Mateo County Health System Groundwater Protection Program (GPP).
Two generations of 550-gallon waste oil USTs also reportedly existed in the automotive repair facility. The first generation steel UST was replaced in 1987 with the second generation UST, which was removed in 1998. Soil samples collected during removal of the second UST reportedly did not indicate the presence of petroleum hydrocarbons or benzene at or exceeding laboratory detection limits or significant concentrations of other fuel-related constituents. No further action was reportedly required.
In 2006, one additional monitoring well was reportedly installed (MW-7) along with the completion of multiple borings. In 2010, two additional groundwater monitoring wells were installed (MW-1R and MW-3R), along with seven multilevel soil vapor probes, five additional borings along the perimeter of the project area, and one subslab vapor point beneath the tire storage area of the former automotive repair facility.
In 2011, two additional groundwater monitoring wells were installed (MW-8 and MW-9), along with one dual completion soil vapor well (SV-9) and one additional subslab probe beneath the former automotive repair facility. In addition, monitoring wells MW-1 through MW-3, MW-5, and MW-6 were destroyed per the approval of GPP.
In 2012, one additional groundwater monitoring well (MW-10), one deep soil vapor extraction (SVE) well, one shallow SVE well, four observation wells (OBS-1 through OBS-4), and two 4-3
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In February 2013, a 5-day SVE pilot test was performed that resulted in the recommendation of the installation and operation of a full-scale SVE system to target and reduce residual petroleum hydrocarbons in the shallow subsurface.
In 2013, GPP responded to Site activities by requesting a revised Site Management Plan that specified the timing of plan implementation; the method, location, and frequency of air monitoring; and the requirements for implementation of engineering controls, including a description of the controls to be used. GPP also stated that it had not been demonstrated that SVE would sufficiently mitigate vapor intrusion risks into buildings proposed as part of Site development. GPP also indicated that SVE was not considered a remedy sufficient to effectively remove the petroleum hydrocarbon source from the subsurface. Consequently, GPP requested engineering controls be considered and incorporated into the design of the proposed building to mitigate the risk of vapor intrusion and remediation wells/equipment for adequate remediation of residual hydrocarbons.
Ten in-ground hydraulic lifts and five hydraulic reservoirs were removed on April 8 and 9, 2014.
Confirmation soil samples were collected from each of the hydraulic lift pit excavations and the analytical results were compared to residential Environmental Screening Levels (ESLs). Soil at areas with confirmation sample results exceeding ESLs were over-excavated to the lateral and vertical dimension limits possible within the current building. However, impacts exceeding the ESLs remained in three of the excavation areas. Physical limitations (overhead clearance and excavator reach depth) prohibited additional depth excavations at that time.
In July 2014, Stantec prepared and submitted a Revised Remedial Action Plan (Revised RAP).
The Revised RAP prescribed abandonment of Site groundwater monitoring wells from the area of planned excavation, removal and disposal of petroleum-affected soil to a depth of approximately 20 feet bgs, excavation backfilling and compaction, and post-excavation soil vapor and groundwater monitoring and reporting. GPP approved the Revised RAP, and Chevron (the current Responsible Party) implemented the Revised RAP.
Subsequently, four borings were advanced to depths of 20 to 32 feet bgs at various locations at the Site that were chosen specifically in response to a request from the GPP to evaluate lateral and vertical definition of the impacts that could not be excavated due to the physical limitations described above. Based on laboratory analytical results, all contaminants of concern in the samples from these borings were reported to be less than the ESLs.
The automotive repair facility was removed in May 2016, allowing access to the remaining TPH as oil impact in discrete areas. Additional soil was excavated from these areas and the analytical results indicated that the remaining impacts were removed. Based on Stantec’s discussion with GPP at the time of receipt of the data, GPP had no further requirements for Bridgestone Retail Operations (the responsible party) at this location. The excavations were backfilled and compacted, and the excavated soil and other associated wastes generated by the investigation and remedial activities were disposed of in accordance with applicable regulations. 4-4
P:\2516 SteelWave Acquisitions\2516002 180 El Camino Real SSF\Deliverables\2020 Ph I ESA\2020 Ph I ESA Rpt.docx Q u a li t y S e r v i c e f o r E n v i r o nm e n ta l So l u t i o n s | f a r a ll o n c o n s ul t i n g . c om In June 2018, Chevron’s consultant, SCS Engineers (SCS), submitted a revised remedial action plan completion report for the former gasoline service station on the Site. SCS implemented the Stantec Revised RAP, which included test pit excavations, soil profiling, monitoring well and monitoring probe abandonment, and excavation and disposal of approximately 4,220 cubic yards of soil and construction material/concrete from the Site.
In January 2020 (mistakenly written as 2019), SCS submitted a summary letter related to a soil vapor assessment conducted at the former gasoline service station and automotive repair facility on the Site. SCS concluded that the presence of elevated concentrations of TPHg in soil vapor, the laboratory notation regarding high organic content in soil vapor samples, and the relatively higher methane concentrations in the excavation core soil vapor probes indicated natural degradation of the residual petroleum hydrocarbons is occurring, generating methane, and using the available oxygen. SCS further concluded that the data demonstrate active, natural degradation of residual petroleum hydrocarbons in the Site subsurface and that this process has created an oxygen deficiency in the subsurface. The summary letter is included in Appendix C.
SCS proposed to conduct a short-term (2-week) SVE pilot test using a mobile thermal/catalytic oxidizer to withdraw soil vapor from probes and wells installed to depths of 5 to 20 feet within the excavated and backfilled area at the Site. The pilot test is expected to reduce the residual mass of petroleum-affected soil vapor and increase oxygen concentration within the clean backfilled area.
In February 2020, GPP responded to Chevron’s rejection of SCS’s recommendations, stating longterm creation of a bioattenuation zone was unlikely. GPP required a work plan to perform vapor extraction that targets residual sorbed mass or a vapor mitigation and monitoring plan for the future buildings potentially impacted by soil vapor. GPP required this work no later than June 2020; however, at the time of this report, no additional information had been submitted. A copy of the GPP response is included in Appendix C.
Environmental Agreement
Farallon was provided an Environmental Agreement (Agreement) dated September 8, 2017, entered into by and between Chevron Environmental Management Company (EMC), for itself and as attorney-in-fact for Union Oil Company of California, and Shamaim, Inc. (the Site owner). The Agreement indicates that EMC would pay for the implementation of a Revised Remedial Action Plan and other environmental costs within a specified time period. As of the date of this report, the former gasoline service station has not received regulatory closure for historical releases. A copy of the Agreement is included as Appendix C.
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5.0 SITE BACKGROUND AND HISTORY
Farallon reviewed the following historical sources as part of this Phase I ESA:
• Aerial photographs of the South San Francisco, California area dated 1930, 1941, 1946, 1956, 1960, 1968, 1974, 1982, 1987, 1993, 2005, 2006, 2009, 2010, 2012, 2014, 2016, 2018, and 2020 obtained from ERIS; and dated 1993 through 2020 obtained from Google Earth;
• City directories of South San Francisco, California dated 1961, 1966, 1970, 1977, 1982, 1987, 1991, 1996, 2001, 2006, 2008, 2013, and 2018 obtained from ERIS; • U.S. Geological Survey topographic maps of South San Francisco, California dated 1896, 1899, 1915, 1939, 1947, 1950, 1956, 1968, 1973, 1980, 1995, 1996, and 2015 obtained from ERIS; and
• Fire insurance maps for the Site dated 1949, 1953, 1956, and 1970 obtained from ERIS.
Farallon is not responsible for the accuracy or completeness of the historical sources reviewed.
The historical sources documented were reasonably ascertainable and practically reviewable during this Phase I ESA.
SITE
The earliest records for the Site, topographic maps from 1896 through 1939, showed that the Site was undeveloped until approximately the 1930s. The aerial photograph from 1930 showed what appeared to be a farmhouse or other small structure in the center of the Site; the remaining portions of the Site appeared to be agricultural fields.
The 1946 aerial photograph shows what appears to be military-style barracks or some other rudimentary housing along the southern and eastern portions of the Site. Reportedly, prior to current development of the Site, which occurred in the mid-1960s, the Site was part of the Tanforan horse racetrack, southeast of the Site. The Site was not on the track itself, but on the northwestern portion of the Tanforan racetrack property. In 1911, the Tanforan racetrack was reportedly turned into a military training site until the end of World War I, when the property returned to use as a horse racetrack. In 1942, the entire Tanforan property was temporarily used by the U.S. Army as an assembly center for people of Japanese ancestry. Approximately 8,000 Japanese persons were reportedly processed at this location. Between 1943 and 1946, the property was occupied by the U.S. Navy for troop housing and returned to use as a racetrack after 1946.
The 1968 aerial photograph showed a gasoline service station and automotive repair facility along with the large multi-tenant retail space. Records intermix the names and addresses of the gasoline service station and automotive repair facility. The addresses include 180 El Camino Real, 190 El Camino Real, and 192 El Camino Real. The names used to represent the businesses at these locations include Firestone #3654, Firestone Complete Auto Care #3654, 1X Firestone Stores #3654, 1X Union Oil Stn #6980, Firestone Tire and Service, Tesoro Gasoline Marketing Co, 5-2
P:\2516 SteelWave Acquisitions\2516002 180 El Camino Real SSF\Deliverables\2020 Ph I ESA\2020 Ph I ESA Rpt.docx Q u a li t y S e r v i c e f o r E n v i r o nm e n ta l So l u t i o n s | f a r a ll o n c o n s ul t i n g . c om Unocal Service Station #6980, Bridgestone Retail Operations LLC, and Union Oil (also called Unocal) Service Station #6980. Environmental investigations at the Site were initiated in April 1992 when three gasoline USTs associated with the gasoline service station were removed and subsequently found to have leaked. Various monitoring and remedial actions were performed by the responsible party and by mid- to late 2016, the removal of the automotive repair facility had been completed.
ADJACENT PROPERTIES
Adjacent properties appeared relatively undeveloped, with the exception of the Tanforan racetrack, until the mid-1940s, when presumed military barracks were constructed on and adjacent to the Site and residential development commenced southwest of the Site. In subsequent years, more infill and localized development surrounding the Site occurred. 6-1
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6.0 REGULATORY REVIEW
ERIS conducted a review of environmental regulatory agency database listings to identify reported environmental issues related to the Site and facilities in the Site vicinity. Farallon used the greater of each approximate minimum search distance from the Site for each of the referenced federal and state environmental databases, as specified in ASTM E1527-13.
Farallon reviewed the results from the ERIS Database Report prepared for the Site dated November 16, 2020 (ERIS Report) to note reported facilities in the vicinity of the Site that were considered to have a potential to adversely impact the Site (i.e., are known to have resulted in or are expected to result in a recognized environmental condition). Reported facilities identified in the ERIS Report were evaluated with respect to the nature and extent of a given release, the distance of the reported facility from the Site, the stratigraphy of soil, the expected soil permeability, and the location of a reported facility with respect to known or expected local and/or regional groundwater flow direction.
The descriptions of the databases searched, the complete database names for the abbreviations used in this Phase I ESA Report, and the associated search distances from the Site are provided in the ERIS Report presented in Appendix D.
ON-SITE LISTINGS
Safeway #3027 (170 El Camino Real) was identified in the DELISTED HAZ, SA MATEO CUPA, HAZNET, and FINDS/FRS databases. The identification of this address and business in the above databases is attributed to grocery store handling of organic (food wastes) and pharmaceutical products. There are no indications that the listings in the databases above would represent a recognized environmental condition in connection with the Site.
Firestone #3654 (180 El Camino Real) was identified in the HIST TANK and HHSS databases.
The identification of this address and business in the above databases is attributed to facilities at this address historically conducting automotive repair work and storing chemicals and petroleum products. The addresses of 192 El Camino Real and 190 El Camino Real likely have been combined with 180 El Camino Real in some of the database records. Records from this address note that it is a leaking UST cleanup site with impacts to groundwater.
CVS Pharmacy #9899, Longs Drug Store #9899, and Longs Drug Store #266 (186 El Camino Real) were identified on the DELISTED HAZ, SAN MATEO CUPA, HAZNET, FINDS/FRS, and RCRA LQG databases. The identification of this address and business in the above databases is attributed to pharmaceutical product use and wastes. There are no indications that the listings in the databases above would represent a recognized environmental condition in connection with the Site.
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NON GEN, DELISTED HAZ, SAN MATEO CUPA, HIST MANIFEST, HAZNET, CHMIRS, FINDS/FRS, and RCRA SQG databases. The identification of this address and business in the above databases is attributed to facilities at this address (190 El Camino Real) historically conducting automotive repair work and storing chemicals and petroleum products. The addresses of 192 El Camino Real and 190 El Camino Real likely have been combined with 180 El Camino Real in some of the database records. Additionally, petroleum spills (hydraulic oil) reported on April 8 and 23, 2014 were noted as impacting soil but not groundwater The hydraulic oil was reportedly a residual oil from removal of in-ground lifts.
Union Oil (also called Unocal) Service Station #6980 (192 El Camino Real) was also identified in the RCRA NON GEN, DELISTED HAZ, SAN MATEO CUPA, HIST MANIFEST, HAZNET, CHMIRS, FINDS/FRS, RCRA SQG, HIST CHMIRS, HIST TANK, HHSS, and LUST databases.
The identification of this address and business in the above databases is attributed to facilities at this address (192 El Camino Real) historically conducting automotive repair work and storing chemicals and petroleum products. The addresses of 192 El Camino Real and 190 El Camino Real likely have been combined with 180 El Camino Real in some of the database records. Records from this address note that it is a leaking UST cleanup site that has impacted groundwater; there have also been notices of violations issued to that address, which is consistent with the records reviewed in the GeoTracker database.
Farallon searched the GeoTracker database and the EnviroStor database for records related to the Site. Additional information regarding the Site is provided in Section 4.5, Previous Environmental Studies.
ADJACENT AND OTHER FACILITY LISTINGS
Reported facilities within 0.25 mile up-gradient, 0.125 mile cross-gradient, or adjacent down-gradient of the Site with respect to the assumed groundwater flow direction are considered to have a potential to have impacted the Site. Facilities that were listed in the ERIS Report but not identified as a reported facility (e.g., a facility listed as a hazardous waste generator but not as having had a release), and facilities that were listed as “Closed” were not considered to have a potential to have impacted the Site.
• Former Chevron 209437, at 409 South Spruce Avenue, north- and east-adjacent to the Site and at a lower topographic elevation, was identified in SAN MATEO LOP, LUST, and FINDS/FRS databases. This was a facility that released fuels to groundwater but has been subsequently granted regulatory closure as of December 3, 2002. Based on its location relative to the Site and the regulatory status, this facility is not considered a recognized environmental condition in connection with the Site.
• Tony’s Services, Brentwood Service Station, Texaco, SFBay Fuel LLC, Brentwood Auto Repair, Kwik Service Station, Convenient Auto Care, Grand Gas South San Francisco, and Salkhi Petroleum Inc., at 209 El Camino Real, north- and west-adjacent 6-3
P:\2516 SteelWave Acquisitions\2516002 180 El Camino Real SSF\Deliverables\2020 Ph I ESA\2020 Ph I ESA Rpt.docx Q u a li t y S e r v i c e f o r E n v i r o nm e n ta l So l u t i o n s | f a r a ll o n c o n s ul t i n g . c om across El Camino Real to the Site and at a slightly higher topographic elevation, was identified in UST, DELISTED HAZ, DELISTED CTNK, SAN MATEO CUPA, HHSS, LUST, DELISTED TNK, RCRA NON GEN, CERS HAZ, CHMIRS, HAZNET, and FINDS/FRS databases. This was a facility that released fuels to groundwater and is currently being remediated. Groundwater flow is reportedly to the north, away from the Site. Based on its location relative to the Site and the regulatory status, this facility is not considered a recognized environmental condition in connection with the Site. • Sees Candies Inc., at (210 El Camino Real), north-adjacent across South Spruce Avenue to the Site and at a slightly higher topographic elevation, was identified in RCRA NON GEN, EMISSIONS CERS HAZ, LUST, SAN MATEO CUPA, SAN MATEO LOP, and RCRA SQG databases. This was a facility that released fuels to groundwater and was granted regulatory closure as of January 18, 2001. Based on its location relative to the Site and the regulatory status, this facility is not considered a recognized environmental condition in connection with the Site.
Farallon reviewed the GeoTracker and EnviroStor databases for surrounding properties, and found information regarding several “Closed” facilities, none of which represent a recognized environmental condition in connection with the Site based on the above criteria.
UNMAPPABLE LISTINGS
ERIS identified five facilities as “unplottable” that ERIS was unable to map due to inaccurate or inadequate address information. None of these unplottable facilities listed in the ERIS Report was considered to represent a recognized environmental condition in connection with the Site. 7-1
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7.0 INTERVIEWS
Farallon conducted interviews with individuals familiar with the Site and contacted relevant local governmental agencies to obtain additional Site information. The responses from the parties contacted are provided below.
INTERVIEW WITH SITE REPRESENTATIVE
Farallon was not provided with a Site representative to interview, which represents a data gap.
However, because changes to the Site use and layout during known commercial periods are well documented and environmental investigations have been conducted at the Site and surrounding areas, this data gap is not considered significant and is not expected to hinder the conclusions of this report.
INTERVIEW WITH FIRE DEPARTMENT
Farallon contacted the South San Francisco Fire Department on December 1, 2020 regarding records related to previous and current aboveground storage tanks (ASTs) and USTs at the Site.
No response from the South San Francisco Fire Department was received prior to completion of this Phase I ESA Report, which represents a data gap. However, because changes to the Site use and layout during known commercial periods are well documented and environmental investigations have been conducted at the Site and surrounding areas, this data gap is not considered significant and is not expected to hinder the conclusions of this report.
INTERVIEW WITH CITY OF SAN FRANCISCO OFFICE OF THE CITY CLERK Farallon contacted the City of South San Francisco Office of the City Clerk on December 1, 2020 regarding previous and current ASTs and USTs at the Site. The City of South San Francisco Office of the City Clerk indicated it had no records to provide.
INTERVIEW WITH SAN MATEO COUNTY ENVIRONMENTAL HEALTH
Farallon contacted San Mateo County Environmental Health on December 1, 2020 regarding previous and current ASTs and USTs at the Site. No response from San Mateo County Environmental Health was received prior to completion of this Phase I ESA Report, which represents a data gap. However, because changes to the Site use and layout during known commercial periods are well documented and environmental investigations have been conducted on the Site and surrounding areas, this data gap is not considered significant and is not expected to hinder the conclusions of this report.
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8.0 SITE RECONNAISSANCE
Farallon conducted a site reconnaissance on November 23, 2020 to observe the Site for physical evidence of recognized environmental conditions. The methodology used for the site reconnaissance and the observations made during the reconnaissance are discussed below. A description of the Site is provided in Section 2.2, Site Description. Photographs taken during the site reconnaissance are presented in Appendix B.
SITE RECONNAISSANCE METHODOLOGY
Farallon completed a walk around the perimeter of the Site and inspected interior portions of the Site. There were no deviations from ASTM E1527-13 during the Phase I ESA. No limiting conditions were encountered during this Phase I ESA.
SITE RECONNAISSANCE OBSERVATIONS
Weather conditions at the time of the reconnaissance were sunny, with a temperature of approximately 75 degrees Fahrenheit. No weather-related Site-access restrictions were encountered during the reconnaissance.
The Site consists of San Mateo County Assessor’s Parcel No. 014-183-110, which totals approximately 14.5 acres of land. The Site contains remnants of former shopping center retail businesses and a former gasoline service station and auto repair facility. The shell of the shopping center’s main building, which totals approximately 140,000 square feet, remains standing. The Site is currently surrounded by a perimeter fence to prevent unlawful access. Remaining areas of the Site consist of asphalt-paved parking and landscaped areas. Access to the Site is gained from Huntington Avenue, northeast of the Site, El Camino Real, southwest of the Site, and South Spruce Avenue, northwest of the Site.
Interior Observations
Farallon observed the interior of the Site building shell during the site reconnaissance. However, no notable observations of the Site building shell were identified. Photographs taken during the site reconnaissance are provided in Appendix B.
Exterior Observations
Farallon’s observations of the exterior of the Site during the site reconnaissance are documented in the table below. Comments pertaining to notable exterior observations follow in Section 8.2.3.
Photographs taken during the site reconnaissance are provided in Appendix B.
EXTERIOR OBSERVATIONS YES NO
Odor X
Staining and/or Corrosion X
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EXTERIOR OBSERVATIONS YES NO
Storage Tank(s), Vent Pipe(s), and/or Fuel Port(s) X
Drum(s) and/or Other Container(s) X
Pool(s) of Liquid X
Hazardous Material(s) and/or Petroleum Product(s) X
Hazardous Waste X
Pit(s), Pond(s), and/or Lagoon(s) X
Stressed Vegetation X
Solid (Non-Hazardous) Waste—Evidence of Dumping X
Monitoring Well(s) X
Wastewater X
Domestic Water X
Water Well(s) X
Septic/Sewer System X
Stormwater X
Transformer(s) X
Significant Amount of Fill Material X
Exterior Observation Comments
Monitoring Well(s)
Farallon observed four monitoring well covers in the northwestern portion of the Site where the former gasoline service station and automotive service area had been present. The well covers were bolted shut and not accessed. These well covers are inferred to contain vapor monitoring points, which are part of the remedial activities being completed at this location. 9-1
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9.0 FINDINGS AND OPINIONS
The earliest records for the Site, topographic maps from 1896 through 1939, showed that the Site was undeveloped until approximately the 1930s. The aerial photograph from 1930 showed what appeared to be a farmhouse or other small structure in the center of the Site; the remaining portions of the Site appeared to be agricultural fields.
The 1946 aerial photograph shows what appears to be military-style barracks or some other rudimentary housing along the southern and eastern portions of the Site. Reportedly, prior to current development of the Site, which occurred in the mid-1960s, the Site was part of the Tanforan horse racetrack, southeast of the Site. The Site was not on the track itself, but on the northwestern portion of the Tanforan racetrack property. In 1911, the Tanforan racetrack was reportedly turned into a military training site until the end of World War I, when the property returned to use as a horse racetrack. In 1942, the entire Tanforan property was temporarily used by the U.S. Army as an assembly center for people of Japanese ancestry. Approximately 8,000 Japanese persons were reportedly processed at this location. Between 1943 and 1946, the property was occupied by the U.S. Navy for troop housing and returned to use as a racetrack after 1946.
The 1968 aerial photograph showed a gasoline service station and automotive repair facility along with the large multi-tenant retail space. Environmental investigations at the Site were initiated in April 1992 when three gasoline USTs associated with the gasoline service station were removed and subsequently found to have leaked. Various monitoring and remedial actions were performed by the responsible party and by mid- to late 2016, the removal of the automotive repair facility had been completed.
SteelWave Acquisitions, LLC provided Farallon with previous environmental studies prepared for the former gasoline service station and automotive repair facility on the Site. Additionally, Farallon searched the GeoTracker database and the EnviroStor database for records related to the Site.
These records dated back to 2005 and included groundwater monitoring reports, site investigation reports, remedial action plans, and requests for closure. Farallon reviewed pertinent environmental studies related to the former gasoline service station and automotive repair facility on Site. As recently as January 2020, environmental regulators required a work plan to perform vapor extraction that targets residual sorbed mass from the soil and/or a vapor mitigation and monitoring plan for the future buildings potentially impacted by soil vapor. The San Mateo County Environmental Health Groundwater Protection Program required this work no later than June 2020; however, at the time of this report, no additional information had been submitted.
Farallon was provided an Agreement dated September 8, 2017, entered into by and between EMC, for itself and as attorney-in-fact for Union Oil Company of California, and Shamaim, Inc. (the Site owner). The Agreement indicates that EMC would pay for the implementation of a Revised Remedial Action Plan and other environmental costs within a specified time period. As of the date of this report, the former gasoline service station has not received regulatory closure for historical releases.
9-2
P:\2516 SteelWave Acquisitions\2516002 180 El Camino Real SSF\Deliverables\2020 Ph I ESA\2020 Ph I ESA Rpt.docx Q u a li t y S e r v i c e f o r E n v i r o nm e n ta l So l u t i o n s | f a r a ll o n c o n s ul t i n g . c om Based on review of reasonably ascertainable information, the release of hazardous substances or petroleum products in connection with historical operations at the former gasoline service station and automotive repair facility on the northwestern portion of the Site represents a recognized environmental condition in connection with the Site..
The ERIS Report identified the Site address in several databases. The identification of the Site in the databases is attributed to historical activities such as waste management, waste reporting, etc., at the commercial retail portions of the Site (grocery stores, pharmacies, etc.), along with chemical uses and releases associated with the former gasoline service station and automotive repair facility on the northwestern portion of the Site. Other than the documented releases associated with the former gasoline service station and automotive repair facility, there are no indications that the listings on the databases for the other portions of the Site indicate a release or threatened release that would represent a recognized environmental condition in connection with the Site. 10-1
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10.0 CONCLUSIONS
Farallon conducted a Phase I ESA for the properties located at 170 to192 El Camino Real in South San Francisco, California in conformance with the scope and limitations of ASTM E1527-13. Any exceptions to or deletions from this practice are described in Section 1.5, Deviations.
Based on review of the Site history, reconnaissance of the Site, and review of regulatory agency lists, this Phase I ESA identified the following recognized environmental condition in connection with the Site:
• The release of hazardous substances or petroleum products in connection with historical operations at the former gasoline service station and automotive repair facility on the northwestern portion of the Site.
This recognized environmental condition is currently being overseen by the San Mateo County Environmental Health Groundwater Protection Program and includes ongoing remedial efforts.
Additional records reviewed indicate an Environmental Agreement between Chevron Environmental Management Company and Shamaim, Inc., where Chevron Environmental Management Company agrees to conduct certain remedial work on the impacted property over a certain time period. As of the date of this report, the former gasoline service station has not received regulatory closure for historical releases.
11-1
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11.0 REFERENCES
San Mateo County Assessor’s Office. 2020. Property Search Information for Parcel No. 014-183- 110. <https://gis.smcgov.org/Html5Viewer/?viewer=raster>. (December 1, 2020.) California Department of Conservation, Geologic Energy Management Division. 2016. Well Finder Database Search.
<https://www.conservation.ca.gov/calgem/Pages/WellFinder.aspx>. (December 1, 2020.) California Department of Toxic Substances Control. 2016. EnviroStor Database Search. <https://www.envirostor.dtsc.ca.gov/public/>. (October 5, 2020.) California Department of Water Resources Sustainable Groundwater Management Office. 2016.
California’s Groundwater. Bulletin 118. Revised December 22.
California State Water Resources Control Board. 2016. GeoTracker Database Search. <http://geotracker.waterboards.ca.gov>. (October 5, 2020.) Environmental Risk Information Services. 2020. Fire Insurance Maps. 180 El Camino Real, South San Francisco, California 94080. November 16.
———. 2020. Database Report. 180 El Camino Real, South San Francisco, California 94080.
November 16.
———. 2020. Physical Setting Report. 180 El Camino Real, South San Francisco, California 94080.
November 16.
———. 2020. Historical Aerials. 180 El Camino Real, South San Francisco, California 94080.
November 17.
———. 2020. City Directory. 180 El Camino Real, South San Francisco, California 94080. November
19. ———. 2020. Topographic Maps. 180 El Camino Real, South San Francisco, California 94080.
November 24.
Farallon Consulting, L.L.C. 2020. Letter regarding Proposal for Phase I Environmental Site Assessment, 180 El Camino Real, South San Francisco, California. From Martin Hamann and Richard Makdisi. To Bridget Metz, SteelWave Acquisitions, LLC. November 10. ———. 2020. Inquiry Regarding Permits for Aboveground and Underground Storage Tanks, Notices of Violations, and Hazardous Spills by a Representative of Farallon to a Representative of South San Francisco Fire Department. December 1. 11-2
P:\2516 SteelWave Acquisitions\2516002 180 El Camino Real SSF\Deliverables\2020 Ph I ESA\2020 Ph I ESA Rpt.docx Q u a li t y S e r v i c e f o r E n v i r o nm e n ta l So l u t i o n s | f a r a ll o n c o n s ul t i n g . c om ———. 2020. Inquiry Regarding Notices of Violations and Hazardous Spills by a Representative of Farallon to a Representative of San Mateo County Environmental Health. December 1. ———. 2020. Interview Regarding Permits for Aboveground and Underground Storage Tanks, Notices of Violations, and Hazardous Spills Between a Representative of Farallon and a Representative of the City of South San Francisco Office of the City Clerk. December 1.
Google Earth. 2020. Aerial Photographs of the South San Francisco, California Area. <https://www.google.com/earth/>. (December 1, 2020.)
San Mateo County Environmental Health Groundwater Protection Program. 2020. Letter regarding Former Unocal Station #6980 (Chevron #306441) at 192 El Camino Real, South San Francisco, California. From Jacob Madden. To Eric Hetrick, Union Oil Company of California c/o Chevron Environmental Management Company. February 6.
SCS Engineers. 2015. Phase I Environmental Site Assessment, 170 to 192 El Camino Real, South San Francisco, California, Assessor’s Parcel Number (APN) 014-183-110. September 17. ———. 2018. Letter regarding Revised Remedial Action Plan (RAP) Completion Report, 190- 192 El Camino Real, South San Francisco, California. From James G. Ritchie and Ted Sison. To Anne Jurek, San Mateo County Environmental Health Groundwater Protection Program. June 18.
———. 2019 [sic]. Letter regarding Summary Letter, Soil Vapor Assessment, Chevron 306441/Former Unocal No. 6980, 190-192 El Camino Real, South San Francisco, California, SMCO Case #550098. From Natasha Maranhas and James G. Ritchie. To Jacob Madden, San Mateo County Environmental Health Groundwater Protection Program. January 8.
Stantec. 2014. Revised Remedial Action Plan, Chevron 306441 (Former Unocal No. 6980), 190- 192 El Camino Real, South San Francisco, California. Prepared for Chevron Environmental Management Company. July 8.
———. 2014. Third Quarter 2014 Annual Groundwater Monitoring Report, Chevron 306441 (Former Unocal No. 6980), 190-192 El Camino Real, South San Francisco, California.
Prepared for Chevron Environmental Management Company. November 13. 12-1
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12.0 LIMITATIONS
GENERAL LIMITATIONS
The conclusions contained in this report/assessment are based on professional opinions with regard to the subject matter. These opinions have been arrived at in accordance with currently accepted hydrogeologic and engineering standards and practices applicable to this location. The conclusions contained herein are subject to the following inherent limitations:
• Accuracy of Information. Farallon obtained, reviewed, and evaluated certain information used in this report/assessment from sources that were believed to be reliable. Farallon’s conclusions, opinions, and recommendations are based in part on such information.
Farallon’s services did not include verification of its accuracy or authenticity. Should the information upon which Farallon relied prove to be inaccurate or unreliable, Farallon reserves the right to amend or revise its conclusions, opinions, and/or recommendations. • Reconnaissance and/or Characterization. Farallon performed a reconnaissance and/or characterization of the Site that is the subject of this report/assessment to document current conditions. Farallon focused on areas deemed more likely to exhibit hazardous materials conditions. Contamination may exist in other areas of the Site that were not investigated or were inaccessible. Site activities beyond Farallon’s control could change at any time after the completion of this report/assessment.
For the foregoing reasons, Farallon cannot and does not warrant or guarantee that the Site is free of hazardous or potentially hazardous substances or conditions, or that latent or undiscovered conditions will not become evident in the future. Farallon’s observations, findings, and opinions can be considered valid only as of the date of the report.
This report/assessment has been prepared in accordance with the contract for services between Farallon and SteelWave Acquisitions, LLC, and currently accepted industry standards. No other warranties, representations, or certifications are made.
LIMITATION ON RELIANCE BY THIRD PARTIES
Reliance by third parties is prohibited. This report/assessment has been prepared for the exclusive use of SteelWave Acquisitions, LLC to address the unique needs of SteelWave Acquisitions, LLC at the Site at a specific point in time.
This is not a general grant of reliance. No one other than SteelWave Acquisitions, LLC may rely on this report unless Farallon agrees in advance to such reliance in writing. Any unauthorized use, interpretation, or reliance on this report/assessment is at the sole risk of that party, and Farallon will have no liability for such unauthorized use, interpretation, or reliance.
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FIGURES
PHASE I
ENVIRONMENTAL SITE ASSESSMENT REPORT
180 El Camino Real
South San Francisco, California
Farallon PN: 2516-002
Checked By: MH Disc Reference:
FARALLON PN: 2516-002
³ SITE VICINITY MAP
170 to 192 EL CAMINO REAL
SOUTH SAN FRANCISCO, CALIFORNIA
Washington
Issaquah | Bellingham | Seattle
Oregon
Portland | Baker City
California
CONSULTING Oakland | Folsom | Irvine
Quality Service for Environmental Solutions | farallonconsulting.com Farallon
Drawn By: vpehlivan Date: 12/8/2020
Q:\Projects\2516 Steel Wave Acquisitions\2516002 180 El Camino Real SSF\Mapfiles\001 Phase I\Figure-01_SiteVicinityMap.mxd FIGURE 1
REFERENCE: 7.5 MINUTE USGS QUADRANGLE SAN FRANCISCO SOUTH, CALIFORNIA, DATED 2013 0 5,000
SCALE IN FEET
!(
SOUTH
SAN FRANCISCO
SITE LOCATION
Service Layer Credits:
Checked By: MH Disc Reference:
FIGURE 2
FARALLON PN: 2516-002
H!
<! <!
<!
<!
EL CAMINO REAL
NOOR AVENUE
RESIDENTIAL DRIVE WAY
COMMERCIAL/RETAIL
DRIVE WAY
ASPHALT
PAVEMENT
MOVIE
THEATER COMMERCIAL
G
LOADING
DOCK
G
FORMER
USTs
G
EXISTING
BUILDING
SHELL
G
CONSTRUCTION
EQUIPMENT
G
DRIVE WAY
G
FORMER
FIRESTONE
SHOP
CONSTRUCTION
MATERIALS
ASPHALT
PAVEMENT
DRIVE WAY
ASPHALT
PAVEMENT
G
COLLAPSED
ROOF COMMERCIAL/
RETAIL
HUNTINGTON AVENUE
DRIVE WAY G
SEE'S CANDY
MANUFACTURING
PLANT
G
FORMER
GARDEN AREA
G
LOADING
DOCK
AT&T
SERVICES
SOUTH SPRUCE AVENUE
ASPHALT
PAVEMENT
DRIVE WAY
G
CONSTRUCTION
MATERIALS
OFFICE
BUILDING
GOODWILL
STORE
COUNTY
HUMAN
SERVICES
AGENCY
SELF SERVICE
CAR WASH
³
SITE PLAN
170 to 192 EL CAMINO REAL
SOUTH SAN FRANCISCO, CALIFORNIA
Washington
Issaquah | Bellingham | Seattle
Oregon
Portland | Baker City
California
Oakland | Folsom | Irvine CONSULTING
Farallon
Date: 12/8/2020
LEGEND
H! BORING (ABANDONED)
<! MONITORING WELL
SOIL
SITE BOUNDARY
SAN MATEO COUNTY
PARCEL BOUNDARY
0 200
SCALE IN FEET
Drawn By: vpehlivan
Path: Q:\Projects\2516 Steel Wave Acquisitions\2516002 180 El Camino Real SSF\Mapfiles\001 Phase I\Figure-02_SitePlan.mxd Quality Service for Environmental Solutions | farallonconsulting.com NOTES:
1. ALL LOCATIONS ARE APPROXIMATE.
2. FIGURES WERE PRODUCED IN COLOR. GRAYSCALE COPIES MAY NOT REPRODUCE ALL ORIGINAL INFORMATION.
UST = UNDERGROUND STORAGE TANK
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APPENDIX A
PROFESSIONAL QUALIFICATIONS
PHASE I
ENVIRONMENTAL SITE ASSESSMENT REPORT
180 El Camino Real
South San Francisco, California
Farallon PN: 2516-002
Washington
Issaquah | Bellingham | Seattle
Oregon
Po r tland | Baker City
Cali fo rnia
Oakland | Folsom | Irvine
Q u al i t y S e r vi c e f o r E n v i r o nm e n t a l Sol u ti o ns | f a r a l lo nc o n s ul ti n g . c om MARTIN HAMANN, P.G., L.G.
Principal Geologist
MBA
BA Geology
30 years experience
Mr. Hamann has worked on hundreds of environmental health and safety programs, regulatory negotiations, sustainability issues, site investigations, environmental assessments, and remedial actions. He manages and works on numerous large environmental projects at industrial facilities, and has extensive experience with large-scale water development and environmental projects in the United States and developing countries. Mr. Hamann also serves as a designated technical expert, providing litigation support services on complex soil and groundwater contamination projects and environmental health and safety issues.
RICHARD MAKDISI, P.G.
Principal Geochemist
MS Geochemistry
BA Geology
36 years experience
Mr. Makdisi has more than 36 years of experience in hazardous management, geoscience engineering, geochemistry, and geohydrology. He has hands-on experience managing regional and site facility-scale projects for a wide range of issues, from immediate response assessments to long-term planning studies. He has worked closely with the U.S. Environmental Protection Agency; the California Environmental Protection Agency; California Water Boards; and county and city agencies on Resource Conservation and Recovery Act and Comprehensive Environmental Response, Compensation, and Liability Act sites to design and implement remedies to achieve regulatory closure for commercial and government clients. He has extensive experience in evaluating pathways of exposure to identify and design remediation systems and oversee their implementation.
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APPENDIX B
SITE PHOTOGRAPHS
PHASE I
ENVIRONMENTAL SITE ASSESSMENT REPORT
180 El Camino Real
South San Francisco, California
Farallon PN: 2516-002
Washing ton
Is saquah | Bellingham | Seat tle
Oregon
Portland | Baker City
Cali fornia
Oakland | Folsom | Irvine
1 Q u a li t y S e r v i c e f o r E n v i r o nm e n t a l So l u t i o n s | f a r a ll o n c o n su l t i n g . c om
SITE PHOTOGRAPHS
Phase I Environmental Site Assessment Report
170 through 192 El Camino Real
South San Francisco, California
Farallon PN: 2516-002
Photograph 1: Exterior of Site building.
Photograph 2: Exterior of Site building.
Photograph 3: Exterior of Site building.
Photograph 4: Construction equipment storage on eastern portion of Site.
Photograph 5: Construction equipment stored on southeastern portion of Site.
Photograph 6: Monitoring well on northwestern corner of Site.
Photograph 7: Abandoned monitoring well on northwestern corner of Site.
Photograph 8: Construction materials storage on north-central portion of Site.
Photograph 9: Interior of Site building.
Photograph 10: Interior of Site building with collapsed roof.
Photograph 11: Interior of Site building.
Photograph 12: Fire safety line in northern portion of Site building.
SITE PHOTOGRAPHS (continued)
Phase I Environmental Site Assessment Report
170 through 192 El Camino Real
South San Francisco, California
2 Q u a li t y S e r v i c e f o r E n v i r o nm e n t a l So l u t i o n s | f a r a ll o n c o n su l t i n g . c om Photograph 1: Exterior of Site building.
Photograph 2: Exterior of Site building.
SITE PHOTOGRAPHS (continued)
Phase I Environmental Site Assessment Report
170 through 192 El Camino Real
South San Francisco, California
3 Qu a li ty S e r v i c e f o r E n v i r o nm e n t a l So l uti o n s | f a r a ll o n c o n s u l t i n g . c om Photograph 3: Exterior of Site building.
Photograph 4: Construction equipment storage on eastern portion of Site.
SITE PHOTOGRAPHS (continued)
Phase I Environmental Site Assessment Report
170 through 192 El Camino Real
South San Francisco, California
4 Qu a li ty S e r v i c e f o r E n v i r o nm e n t a l So l uti o n s | f a r a ll o n c o n s u l t i n g . c om Photograph 5: Construction equipment stored on southeastern portion of Site.
Photograph 6: Monitoring well on northwestern corner of Site.
SITE PHOTOGRAPHS (continued)
Phase I Environmental Site Assessment Report
170 through 192 El Camino Real
South San Francisco, California
5 Qu a li ty S e r v i c e f o r E n v i r o nm e n t a l So l uti o n s | f a r a ll o n c o n s u l t i n g . c om Photograph 7: Abandoned monitoring well on northwestern corner of Site.
Photograph 8: Construction materials storage on north-central portion of Site.
SITE PHOTOGRAPHS (continued)
Phase I Environmental Site Assessment Report
170 through 192 El Camino Real
South San Francisco, California
6 Qu a li ty S e r v i c e f o r E n v i r o nm e n t a l So l uti o n s | f a r a ll o n c o n s u l t i n g . c om Photograph 9: Interior of Site building.
Photograph 10: Interior of Site building with collapsed roof.
SITE PHOTOGRAPHS (continued)
Phase I Environmental Site Assessment Report
170 through 192 El Camino Real
South San Francisco, California
7 Qu a li ty S e r v i c e f o r E n v i r o nm e n t a l So l uti o n s | f a r a ll o n c o n s u l t i n g . c om Photograph 11: Interior of Site building.
Photograph 12: Fire safety line in northern portion of Site building.
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APPENDIX C
SUPPORTING ENVIRONMENTAL DOCUMENTS
PHASE I
ENVIRONMENTAL SITE ASSESSMENT REPORT
180 El Camino Real
South San Francisco, California
Farallon PN: 2516-002
Environmental Consultants & Contractors
January 8, 2019
Project No. 01217233.00
Mr. Jacob Madden via email: [email protected]
Hazardous Materials Specialist
Groundwater Protection Program
San Mateo County Environmental Health
2000 Alameda de las Pulgas, Suite 100
San Mateo, California 94403
Subject: Summary Letter, Soil Vapor Assessment, Chevron 306441/Former Unocal No. 6980, 190-192 El Camino Real, South San Francisco, California, SMCO Case #550098
Dear Mr. Madden:
SCS Engineers (SCS) has prepared this Summary Letter (Letter) on behalf of Shamaim Incorporated (Shamaim), the owner of the property located at 190-192 El Camino Real, South San Francisco, California (the Site, Figure 1) and Chevron Environmental Management Company’s (CEMC). The Site is located on the southeast corner of the intersection of the El Camino Real and Spruce Avenue, in South San Francisco, California (Figures 1 and 2) and is bordered by commercial and retail properties.
This Report presents work conducted by SCS in accordance with the November 14, 2018 Work Plan (SCS, 2018b), as approved by the San Mateo County Health Services Agency, Groundwater Protection Program (GPP) on December 6, 2018 (GPP, 2018). 1 BACKGROUND
The Site is part of a larger land parcel addressed as 170 to 192 El Camino Real, which is also identified as Assessor’s Parcel Number (APN) 014-183-110. Tesoro Companies Inc. (Tesoro) first operated a service station at the Site pursuant to a license agreement with J.C. Penney. In 1984, CEMC’s affiliate, Union Oil Company of California (Union Oil), purchased the service station from Tesoro, and a retail service station commonly referred to as Service Station 306441 (formerly Service Station No. 6980) was operated at the Site. Former station facilities included a sales kiosk, two dispenser islands beneath a shared canopy, a service building (with two service bays and a sales office), three 12,000-gallon capacity gasoline underground storage tanks (USTs) and associated product lines. In April 1992, Union Oil removed the USTs, the product dispensers and associated piping.
Later BFS Retail & Commercial Operations, LLC (BFS) operated a “Firestone Complete Auto Care” facility on a portion of the Site, which included a service building, three service bays and an office.
The building and facilities were demolished in April 2016, and Stantec removed and disposed soil impacted by hydraulic fluid associated with BFS’ former use of hydraulic lifts in its operations under the oversight of the GPP.
Site subsurface conditions have been investigated and remediated under GPP jurisdiction since 1992. In approximately 2007, the W.T. Mitchell Group informed the GPP of plans to redevelop the Mr. Jacob Madden
January 8, 2020