Pismo Beach City Council
September 5, 2023

Converse Consultants
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1.0 INTRODUCTION

This report presents the results of our geotechnical investigation performed for the Central Coast Blue Advanced Water Treatment Project, located at 972 Huber Street, in the City of Grover Beach, San Luis Obispo County, California. The project location is shown on Figure No. 1, Site Location Map.

The purposes of this investigation were to determine the nature and engineering properties of the subsurface soils, and to provide design and construction recommendations for the project.

This report is prepared for the project described herein and is intended for use solely by Carollo Engineers and their authorized agents for design purposes. It should not be used as a bidding document but may be made available to the potential contractors for information on factual data only. For bidding purposes, the contractors should be responsible for making their own interpretation of the data contained in this report.

2.0 PROJECT DESCRIPTION

The proposed advanced water treatment system will have a new building with approximate dimensions of 161 feet x 111 feet. Pump wet wells will be 24 feet deep from building finished floor elevation to top of tank floor. The proposed building will house the following equipment:

 New purified water pump station
 New UV reactor
 New CIP and BW Equalization tanks
 3 - RO train and 4 - MF train
 Chemical Containment area and tanks

We understand that the proposed treatment facility building will be supported on shallow footings and reinforced concrete slab-on-grade foundations. CO2 and chemical tanks will be constructed outside of the building within the project area.

3.0 SITE DESCRIPTION

The proposed Central Coast Blue Advanced Water Treatment Project is located at 972, Huber Street in Grover Beach, California. The proposed project site is bounded by Huber Street on the East, Barca Street and South 4th Street along the West, Calvin Court on the South and by an existing building and parking lot in the North. Ground surface elevations range from approximately 20 to 22 feet above mean sea level. Approximate boring locations are indicated on Figure No. 2, Approximate Boring Location Map. Approximate project coordinates are 35.1108, -120.6229

SITE LOCATION
21-31-323-01
1 SCALE: 1"=3,000'
0 SCALE IN FEET
1,500' 3,000'
REFERENCE: USGS 2018 MAPS

OCEANO QUADRANGLE
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Central Coast Blue Advanced Water Treatment
972 Huber Street, Grover Beach, California
Converse Project No. 21-31-323-01

BH-4
PT-2
BH-2
BH-3
BH-1
BH-5
PT-4
PT-1
PT-3
Central Coast Blue Advanced Water Treatment
972 Huber Street, Grover Beach, California
Converse Project No. 21-31-323-01
For: - CarolloBH-2
PT-3

SPT BOREHOLE

PERCOLATION TEST

Geotechnical Investigation Report
Central Coast Blue Advanced Water Treatment Project
Grover Beach, California
June 15, 2022

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4.0 SCOPE OF WORK

The scope of this investigation included project set-up, subsurface exploration, laboratory testing, engineering analysis, and preparation of this report, as described in the following sections.

4.1 Document Review

We reviewed geologic maps, groundwater data and other information pertaining to the project area to assist in the evaluation of geologic hazards that may be present. Besides, pertinent information (the documents cited in Section 14, References) were used to understand the subsurface conditions and plan the investigation for this project.

4.2 Project Set-up

The project set-up consisted of the following tasks:

 Coordinated with Carollo Engineers and WSC for the site access.  Conducted a field reconnaissance and marked the borings such that the drill rig access to all locations was available.
 Notified Underground Service Alert (USA) at least 48 hours prior to drilling to clear the boring locations of any conflict with existing underground utilities.  Underground utility scanning by GPRS.
 Engaged a California-licensed driller to drill exploratory borings.

4.3 Subsurface Exploration

Five exploratory borings (BH-1 to BH-5) were drilled on May 13, 2022, to investigate the subsurface conditions at the site. The borings were drilled with a truck-mounted drill rig equipped with an 8-inch diameter hollow stem auger. The borings were drilled and sampled to 51.5 feet below existing ground surface (bgs). Additional four (4) borings were drilled at the subject project site and percolation tests were performed utilizing four borings PT-1, PT-2, PT-3 and PT-4, on July 6, 2022. Percolation test results are presented in Appendix D of this report.

Approximate boring locations are indicated in Figure No. 2, Approximate Boring Location Map. For a description of the field exploration and sampling program, see Appendix A, Field Exploration.

Geotechnical Investigation Report
Central Coast Blue Advanced Water Treatment Project
Grover Beach, California
June 15, 2022

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4.4 Laboratory Testing

Representative soil samples of the project site were tested in the laboratory to aid in the soils classification and to evaluate the relevant engineering properties of the soils. These tests included the following:

 In-situ moisture contents and dry densities (ASTM D2216 and ASTM D2937)  Sand Equivalent (ASTM D2419)
 Soil Corrosivity (California Tests 643, 422, and 417)  Fines Content/Passing No. 200 Sieve (ASTM D1140)
 Grain Size Distribution (ASTM D6913)
 Maximum dry density and optimum-moisture content (ASTM D1557)  Direct Shear (ASTM D3080)
 Consolidation (ASTM Standard D2435)

For in-situ moisture and dry density data, see the Logs of Borings in Appendix A, Field Exploration. For a description of the laboratory test methods and test results, see Appendix B, Laboratory Testing Program.

4.5 Analysis and Report Preparation

Data obtained from the field exploration and laboratory testing program was compiled and evaluated. Geotechnical analyses of the compiled data were performed, and this report was prepared to present our findings, conclusions, and recommendations for the project.

5.0 LABORATORY TEST RESULTS

Results of physical and chemical tests performed for this project are presented below.

5.1 Physical Testing

Results of the various laboratory tests are presented in Appendix B, Laboratory Testing Program, except for the results of in-situ moisture and dry density tests which are presented on the Logs of Borings in Appendix A, Field Exploration. The results are also discussed below.

In-situ Moisture and Dry Density
In-situ dry densities and moisture contents of the site soils were determined in accordance with ASTM Standard D2216 and D2937. Dry densities of alluvium soils ranged from 96 to 121 pounds per cubic foot (pcf) with moisture content of 4 to 22 percent.

Sand Equivalent (SE)
One representative sample was tested to evaluate the expansion potential in accordance with ASTM Standard D2419. The test result showed an SE of 24.

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Grover Beach, California
June 15, 2022

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Grain Size Analysis
Two representative samples were tested to determine the relative grain size distribution in accordance with the ASTM Standard D6913. The test results are graphically presented in Drawing No. B-1, Grain Size Distribution Results.

Maximum Dry Density and Optimum Moisture Content
Typical moisture-density relationship test was performed on a representative sample in accordance with ASTM D1557. The results are presented in Drawing No. B-2, Moisture- Density Relationship Results, in Appendix B, Laboratory Testing Program. The laboratory maximum dry density was 122.5 pcf and the optimum moisture content of 8 percent.

Consolidation Test
One representative sample was tested to determine the settlement characteristics of the foundation soils under load in accordance with the ASTM Standard D2435. The test results are graphically presented in Drawing No. B-3, Consolidation Test Results.

Direct Shear
Two direct shear tests were performed on undisturbed representative ring samples under soaked moisture condition in accordance with ASTM Standard D3080. The results are presented in Drawing Nos. B-4a and B-4b, Direct Shear Test Results in Appendix B, Laboratory Testing Program.

5.2 Chemical Testing - Corrosivity Evaluation

One representative soil sample was tested to determine minimum electrical resistivity, pH, and chemical content, including soluble sulfate and chloride concentrations. The purposes of these tests were to determine the corrosion potential of site soils when placed in contact with common pipe materials. These tests were performed by AP Engineers. (Pomona, CA) in accordance with California Tests 643, 422, and 417. The test results are presented in Appendix B, Laboratory Testing Program and summarized below.

 The pH measurement of the tested sample was 8.1
 The sulfate content of the tested sample was 26 ppm (0.026 percent by weight).  The chloride concentration of the tested sample was 21 ppm.  The minimum electrical resistivity when saturated was 12,225 ohm-cm.

6.0 SITE CONDITIONS

A general description of the subsurface conditions and various materials encountered during our field exploration are presented in this section.

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Grover Beach, California
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6.1 Surface Conditions

The ground surface area and the surfaces at the drill sites were not paved with asphalt or concrete. The project site area was undeveloped and used for storage of cars, trucks and recreational vehicles. The ground surface was relatively flat and ranged in elevation from 20 feet to 22 feet above mean seal level.

6.2 Subsurface Profile

The project site area is located on the central California coast on a relative flat coastal plain landform in Grover Beach approximately 0.45 miles from Pacific Ocean. The project site is in a coastal marine environment due to its close proximity to the Pacific Ocean.

The project site is underlain by existing fill soils placed during previous site grading. The fill soils ranged in depth from 4 to 5 feet below existing ground surface and consisted of silty sands and sands. The fill soils are underlain by marine and non-marine alluvial sediments that have gradually filled the coastal margin over time to form a broad coastal plain as shown on Figure No. 3, Regional Geologic Map.

The native alluvial sediments consisted of silty sands, sandy clays, and poorly graded sands with variable amounts of silt. The alluvial sediments were deposited along the coastal margin as flood plain sediments from Arroyo Grande Creek, beach sand deposits and wind-blown sand deposits. The alluvial sediments consisted of medium stiff to very stiff sandy clays and dense to very dense silty sands and sands to the maximum explored depth of 51.5 feet below ground surface (bgs). Some layers and lenses of gravels and small cobbles were encountered in the alluvial sediments.

6.3 Groundwater

Groundwater was encountered at shallow depths during drilling in three (3) of the deeper exploratory borings to a maximum depth of 51.5 feet. Groundwater was encountered in Boring No. 1 at 11 feet, in Boring No. 2 at 13 feet, and in Boring No. 3 at 13.8 feet below existing ground surface. Groundwater was not encountered in Boring Nos. 4 and 5 drilled to a depths of 11.5 feet below existing ground surface. Historically highest groundwater level was interpreted to be approximately 5 feet below ground surface. Groundwater is expected to be encountered during deeper construction of pump wet wells for the project.

In general, groundwater levels fluctuate with the seasons and local zones of perched groundwater may be present within the near-surface deposits due to local conditions or during rainy seasons. Groundwater conditions below any given site vary depending on numerous factors including seasonal rainfall, local irrigation, stream channel flows, estuary flows, sea level, stormwater recharge, groundwater recharge and pumping, among other factors. The regional groundwater table can be expected to be encountered during deeper aspects of the planned construction.

SITE LOCATION
21-31-323-01

NOT TO SCALE
Central Coast Blue Advanced Water Treatment
972 Huber Street, Grover Beach, California
Converse Project No. 21-31-323-01
I:\ACADDRAWINGS\21\31\323\NO.3__GEOLOGICAL MAP.DWG
REFERENCE: OCEANO, CA 2017

Geotechnical Investigation Report
Central Coast Blue Advanced Water Treatment Project
Grover Beach, California
June 15, 2022

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6.4 Excavatability

The surface and subsurface soil materials at the site are expected to be excavatable by conventional heavy-duty earth moving and trenching equipment.

The phrase “conventional heavy duty excavation equipment” is intended to include commonly used equipment such as excavators, scrapers, and trenching machines. It does not include hydraulic hammers (breakers), jackhammers, blasting, or other specialized equipment and techniques used to excavate hard earth material. Selection of an appropriate excavation equipment models should be done by an experienced earthwork contractor.

6.5 Subsurface Variations

Based on the results of the subsurface exploration and our experience, some variations in the continuity and nature of subsurface conditions within the project site should be anticipated. Because of the uncertainties involved in the nature and depositional characteristics of the earth material at the site, care should be exercised in interpolating or extrapolating subsurface conditions between or beyond the boring locations.

7.0 ENGINEERING GEOLOGY

The regional and local geology within the proposed project area is discussed below.

7.1 Regional Geology

The project site is located within the southern portion of the Coast Ranges Geomorphic Province of California. The Coast Ranges Geomorphic Province extends approximately 600 miles from the Oregon border to the Santa Ynez River and fall into two sub-provinces that include the ranges north of San Francisco and those from the San Francisco Bay area south to Santa Barbara County.

The province is dominated by elongate valleys, diverse lithologic rock types and structural features that parallel the San Andreas fault system. The province is a seismically active region. The most prominent of the nearby fault zones include the Suey Fault, West Huasna Fault, Rinconda Fault, Nacimiento Fault, San Marcos Fault, Huer Huero-Cuyama Fault and San Andreas Fault zones.

7.2 Local Geology

Review of geologic mapping indicates that the project site is underlain locally by alluvial sediments derived by active marine and non-marine sedimentation processes occurring along the Pacific Ocean that have gradually filled the coastal basin over time to form a broad coastal plain. These sedimentary deposits consist of unconsolidated alluvium,

Geotechnical Investigation Report
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Grover Beach, California
June 15, 2022

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stream channel deposits and flood deposits from the Arroyo Grande Creek, beach sand deposits and wind-blown sand deposits.

8.0 FAULTING AND SEISMICITY

The project site lies along the central California coastline in southern San Luis Obispo County within the Coast Ranges Geomorphic Province of California. The Coast Ranges province is characterized by northwest trending valleys and mountain ranges which have formed in response to regional tectonic forces along the boundary between the Pacific and North American tectonic plates. The geologic structure is dominated by northwest trending, right-lateral faults, most notably the San Andreas fault system. The Coast Ranges Geomorphic province extends southward from the Oregon border to the Santa Ynez River valley in Santa Barbara County.

The project site is not located within a currently designated State of California Earthquake Fault Zone for surface fault rupture. No surface faults are known to project through or towards the site. The closest known faults to the project site with mapped surface traces is the San Luis Range and Los Osos thrust faults.

As is the case for most areas of Southern California, strong ground shaking resulting from earthquakes associated with nearby and more distant faults may occur at the project site.

During the life of the project, seismic activity associated with active faults can be expected to generate moderate to strong ground shaking at the site.

The project site is situated on a broad alluvial coastal plain along the edge of the Pacific Ocean. This coastal plain has been gradually filled with marine and non-marine sediments. The Arroyo Grande Creek has deposited stream and flood sediments across the coastal plain during Holocene time (0-11,000 years) to form a relatively flat and broad river flood plain where it meets the ocean. Most of the river and stream channel flows are now controlled by Lopez Dam and flood control channels and storm drains which ultimately drain to the Pacific Ocean. Dune sands and beach sands have been deposited as wind-blow deposits near the beaches of the Pacific Ocean.

8.1 Seismic Characteristics of Nearby Faults

The proposed project site is situated in a seismically active region. As is the case for most areas of Southern California, ground-shaking resulting from earthquakes associated with nearby and more distant faults may occur at the project site. During the life of the project, seismic activity associated with active faults can be expected to generate moderate to strong ground shaking at the site. Review of recent seismological and geophysical publications indicates that the seismic hazard for the project site is high.

Table No. 1, Summary of Regional Faults, summarizes selected data of known faults capable of seismic activity within 100 kilometers of the site. The approximate locations of these local and regional faults with respect to the project are shown on Figure No. 4,

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Grover Beach, California
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Southern California Regional Fault Map. The historic epicenters of recent Southern California earthquakes are shown in Figure No. 5, Epicenter Map of Southern California Earthquakes (1800-1999).

Table No. 1, Summary of Regional Faults
Fault Name and Section
Closest
Distance
(mile)
Slip Sense Length
(km)
Slip Rate
(mm/year)
Maximum
Magnitude
San Luis Range (So Margin) 1.33 thrust 64 0.2 7.0
Los Osos 5.64 thrust 44 0.5 7.8
Casmalia (Orcutt Frontal) 12.34 reverse 29 0.3 6.5
Hosgri 12.8 strike slip 171 2.5 7.2
Rinconada 15.04 strike slip 191 1 7.4
Lions Head 16.75 reverse 41 0.02 6.6
Los Alamos-West Baseline 29.75 thrust 28 0.7 6.7
San Juan 31.14 strike slip 68 1 7.0
S. San
Andreas;PK+CH+CC+BB+NM+SM+N
SB

41.82 strike slip 377 n/a 7.9
S. San
Andreas;PK+CH+CC+BB+NM+SM 41.82 strike slip 342 n/a 7.9 S. San Andreas;PK+CH+CC+BB+NM 41.82 strike slip 245 n/a 7.7 S. San Andreas;PK+CH+CC+BB 41.82 strike slip 208 n/a 7.5 S. San Andreas;PK+CH+CC 41.82 strike slip 158 n/a 7.4
S. San Andreas;PK+CH 41.82 strike slip 99 n/a 7.0
S. San Andreas;CH+CC+BB+NM 41.82 strike slip 208 n/a 7.7 S. San
Andreas;PK+CH+CC+BB+NM+SM+N
SB+SSB+BG+CO

41.82 strike slip 548 n/a 6.2
S. San
Andreas;PK+CH+CC+BB+NM+SM+N
SB+SSB+BG

41.82 strike slip 479 n/a 8.1
S. San Andreas;CH+CC 41.82 strike slip 122 n/a 7.3
S. San Andreas;CH+CC+BB+NM+SM 41.82 strike slip 306 n/a 7.9 S. San Andreas;CH 41.82 strike slip 63 34 6.9
(Source: https://earthquake.usgs.gov/cfusion/hazfaults_2008_search/)

8.2 CBC Seismic Design Parameters

Seismic design mapped parameters based on the 2019 California Building Code (CBSC, 2019) are provided in the following table. These parameters were determined using the generalized coordinates (35.1108N, 120.6229W) and the Seismic Design Maps ATC online tool.

35°
34°
33°
121°120°119°118°117°116°115°

PROJECT SITE
Converse Consultants
REFERENCE: PORTION OF CGS 2002 CALIFORNIA FAULT MODEL

MODIFIED FOR USE WITH FRISKSP AND EQFAULT
BY THOMAS F. BLAKE, AUGUST 2004

POLYGONS INDICATE RUPTURE

BLIND THRUST FAULT,

PLANES AND DIP DIRECTION

FAULT SOURCES
Central Coast Blue Advanced Water Treatment
972 Huber Street, Grover Beach, California
Converse Project No. 21-31-323-01
I:\ACADDRAWINGS\21\31\323\NO.4__REGIONAL FAULT MAP.DWG

PROJECT SITE
REFERENCE: PORTION OF EPICENTERS AND AREAS DAMAGED
BY M 5 CALIFORNIA EARTHQUAKES, 1800-1999>

CALIFORNIA DEPARTMENT OF CONSERVATION,
MAP SHEET 49 DATED 2000.
21-31-323-01
Central Coast Blue Advanced Water Treatment
972 Huber Street, Grover Beach, California
Converse Project No. 21-31-323-01Converse Consultants
I:\ACADDRAWINGS\21\31\323\NO.5__EPICENTER.DWG

Geotechnical Investigation Report
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Grover Beach, California
June 15, 2022

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Table No. 2, 2019 CBC Seismic Design Mapped Parameters
Seismic Parameters
Site Coordinates 35.1108N, 120.6229W
Site Class D
Mapped Short period (0.2-sec) Spectral Response Acceleration, SS 1.018g Mapped 1-second Spectral Response Acceleration, S1 0.372g Site Coefficient (from Table 11.4-1), Fa 1.113
Site Coefficient (from Table 11.4-2), Fv 1.7
MCE 0.2-sec period Spectral Response Acceleration, SMS 1.113g MCE 1-second period Spectral Response Acceleration, SM1 0.632g Design Spectral Response Acceleration for short period SDS 0.742g Design Spectral Response Acceleration for 1-second period, SD1 0.422g Site Modified Maximum Peak Ground Acceleration, PGAM 0.515g

8.2.1 Site-Specific Response Spectra

A site-specific response spectrum was developed for the project for a Maximum Considered Earthquake (MCE), defined as a horizontal peak ground acceleration that has a 2 percent probability of being exceeded in 50 years (return period of approximately 2,475 years).

In accordance with ASCE 7-16, Section 21.2 the site-specific response spectra can be taken as the lesser of the probabilistic maximum rotated component of MCE ground motion and the 84th percentile of deterministic maximum rotated component of MCE ground motion response spectra. The design response spectra can be taken as 2/3 of site-specific MCE response spectra but should not be lower than 80 percent of CBC general response spectra. The risk coefficient CR has been incorporated at each spectral response period for which the acceleration was computed in accordance with ASCE 7-16, Section 21.2.1.1.

The 2019 CBC mapped acceleration parameters are provided in the following table.

These parameters were determined using the ATC hazard by location Seismic Design Maps website application, and in accordance with ASCE 7-16 Sections 11.4, 11.6, 11.8,

21.2, and 21.3.

Table No. 3, 2019 CBC Mapped Acceleration Parameters
Site Class D Seismic Design Category D
Ss 1.018 CRS 0.903
S1 0.372 CR1 0.907
Fa 1 0.08 Fv/Fa 0.200
Fv 2.5 0.4 Fv/Fa 1.000
SMS 1.018 T0 0.183

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Site Class D Seismic Design Category D
SM1 0.930 TS 0.914
SDS 0.679 TL 8
SD1 0.620

A site-specific response analysis, using faults within 200 kilometers of the sites, was developed using the computer program EZ-FRISK Version 8.07 (Fugro, 2021).

The weighted mean maximum-rotated horizontal spectral acceleration values were computed by multiplying the weighted mean geometric spectral values derived from four next-generation attenuation (NGA) West 2 ground motion attenuation models by Abrahamson et al. (2014), Boore et al. (2014) and Campbell and Bozorgnia (2014) with the scale factors provided in ASCE 7-16 Section 21.2. An average shear wave velocity at upper 30 meters of soil profile (Vs30) of 270 meters per second, depth to bedrock of with a shear wave velocity 1,000 meters per second at 150 meters below grade, and depth of bedrock where the shear wave velocity is 2,500 meters per second at 2,500 meters below grade were selected for EZ-Frisk Analysis.

The probabilistic response spectrum results and peak ground acceleration for each attenuation relationship are presented in the following table.

Table No. 4, Probabilistic Response Spectrum Data
Attenuation Relationship Probabilistic
Mean
Abrahamson
et al.
(2014)
Campbell-
Bozorgnia
(2014)
Boore et al.
(2014)
Peak Ground Acceleration (g) 0.563 0.573 0.492 0.613

Spectral Period (sec) 2% in 50yr Probabilistic Spectral Acceleration (g)

0.050 0.648 0.587 0.620 0.733

0.100 0.946 0.825 0.869 1.122

0.200 1.226 1.329 1.011 1.303

0.300 1.322 1.514 1.129 1.284

0.400 1.304 1.499 1.186 1.191

0.500 1.219 1.338 1.163 1.133

0.750 0.964 0.980 1.043 0.866

1.000 0.740 0.744 0.818 0.657

2.000 0.353 0.349 0.429 0.276

3.000 0.212 0.204 0.262 0.164

4.000 0.141 0.137 0.169 0.117

Deterministic response spectra parameters were determined using PEER spread sheet and presented in Table No. 4. Following fault parameters were used to calculate the spectrum. Mw–7, RRUP–2.0 km, RJB–2.0 km, Rx–2.0 km and dip angle is 45 degrees. The

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mapped trace of the San Luis Range Fault is located approximately less than 2.0 km from of the project site. Applicable response spectra data are presented in the table below and on Figure No. 6, Site-Specific Design Response Spectrum. These curves correspond to response values obtained from above attenuation relations for horizontal elastic single- degree-of-freedom systems with equivalent viscous damping of 5 percent of critical damping.

Table No. 5, Probabilistic MCER Spectral Acceleration (g) Period
(sec)
2% in 50yr Probabilistic
Spectral Acceleration (g)
Geometric Mean
Risk
Coefficient
CR
Scale Factors
for MCER
Probabilistic MCER
Spectral Acceleration (g)

0.01 0.563 0.903 1.100 0.559

0.05 0.648 0.903 1.100 0.644

0.1 0.946 0.903 1.100 0.940

0.2 1.226 0.903 1.100 1.218

0.3 1.322 0.904 1.125 1.344

0.4 1.304 0.904 1.150 1.356

0.5 1.219 0.905 1.175 1.296

0.75 0.964 0.906 1.238 1.080
1 0.740 0.907 1.300 0.872
2 0.353 0.907 1.350 0.432
3 0.212 0.907 1.400 0.269
4 0.141 0.907 1.450 0.186

Table No 6, Site-Specific Response Spectrum Data
Period
(sec)
84th Percentile
Deterministic
MCE Response
Spectrum, (g)
Site Specific
MCER Spectral
Acceleration (g)
80% CBC Design
Response
Spectrum
Site Specific
Design Spectral
Acceleration (g)

0.01 0.887 0.559 0.235 0.37

0.05 0.986 0.644 0.306 0.43

0.1 1.329 0.940 0.395 0.63

0.2 1.792 1.218 0.543 0.81

0.3 2.172 1.344 0.543 0.90

0.4 2.308 1.356 0.543 0.90

0.5 2.283 1.296 0.543 0.86

0.75 2.006 1.080 0.543 0.72
1 1.720 0.872 0.496 0.58
2 0.831 0.432 0.248 0.29
3 0.515 0.269 0.165 0.18
4 0.336 0.186 0.124 0.12

SITE LOCATION
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I:\ACADDRAWINGS\21\31\323\NO.6__SEISMIC HAZARD MAP.DWG
Central Coast Blue Advanced Water Treatment
972 Huber Street, Grover Beach, California
Converse Project No. 21-31-323-01
Figures No.
21-31-295-01 7
Project No.

SCALE: 1"=3,000'
0 SCALE IN FEET
1,500 3,000
REFERENCE: SAN LUIS OBISPO QUADRANGLE 2021

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The site-specific design response parameters are provided in the following table. These parameters were determined from Design Response Spectra presented in table above and following guidelines of ASCE Section 21.4.

Table No. 7, Site-Specific Seismic Design Parameters
Parameter Value
(5% Damping)
Lower Limit, 80% of
CBC Design Spectra
Site-Specific 0.2-second period Spectral
Response Acceleration, SMS 1.220 0.814
Site-Specific1-second period Spectral
Response Acceleration, SM1 0.872 0.744
Site-Specific Design Spectral Response
Acceleration for short period SDS 0.813 0.543
Site-Specific Design Spectral Response
Acceleration for 1-second period, SD1 0.582 0.496

8.3 Secondary Effects of Seismic Activity

In general, secondary effects of seismic activity on the project site include surface fault rupture, landslides, soil liquefaction, lateral spreading, seismically induced slope instability, earthquake-induced flooding and tsunami and seiches due to seismic shaking.

The site-specific potential for each of these seismic hazards is discussed in the following sections.

Surface Fault Rupture
The project site is not located within a currently designated State of California Earthquake Fault Zone (formerly Alquist-Priolo Special Studies Zones) for surface fault rupture. The Alquist Priolo Earthquake Fault Zoning Act requires the California Geologic Survey to zone “active faults” within the State of California. An “active fault” has exhibited surface displacement within Holocene time (within the last 11,700 years) hence constituting a potential hazard to structures that may be located across it. Essential service structures are required to be set-back at least 50 feet from an active fault. The active fault set-back distance is measured perpendicular from the dip of the fault plane. Based on review of existing geologic information, no know active faults project through or toward the site. The nearest mapped active fault is the San Luis Range (south margin) located east of the project site. The potential for surface rupture resulting from the movement of nearby major faults, or currently unknown faults, is not known with certainty but is considered low.

Landslides
The project site is relatively flat and not located near any hillside terrain. The potential for seismically induced landslides to affect the proposed site is considered to be very low.

Liquefaction
Liquefaction is the sudden decrease in the strength of cohesionless soils

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due to dynamic or cyclic shaking. Saturated soils behave temporarily as a viscous fluid (liquefaction) and, consequently, lose their capacity to support the structures founded on them. The potential for liquefaction decreases with increasing clay and gravel content but increases as the ground acceleration and duration of shaking increase. Liquefaction potential has been found to be the greatest where the groundwater level and loose sands occur within 50 feet of the ground surface. Soil liquefaction generally occurs in submerged sandy soils and non-plastic silts during or after strong ground shaking. There are several general requirements for liquefaction to occur. They are as follows.

 Soils must be submerged
 Soils must be primarily sandy
 Soils must be loose to medium-dense
 Ground motion must be intense
 Duration of shaking must be sufficient for the soils to lose shear resistance

The site is not located within a currently mapped potential liquefaction zone mapped by the California Geologic Survey (CGS). The Oceano Quadrangle has not been mapped by the California Geologic Survey for geologic hazards and liquefaction potential. Based on our liquefaction analyses of Boring No. 2, liquefaction settlement is 0.6 inches for the subject site. Dry sand settlement is negligible. If the proposed development will be constructed 20 feet below ground level, then liquefaction settlement can be negligible.

Lateral Spreading
Seismically induced lateral spreading involves primarily lateral movement of earth materials due to ground shaking. It differs from the slope failure in that complete ground failure involving large movement does not occur due to the relatively smaller gradient of the initial ground surface. Lateral spreading is demonstrated by near-vertical cracks with predominantly horizontal movement of the soil mass involved. The topography at the project site and in the immediate vicinity of the site is relatively flat, with no significant nearby slopes or embankments. Under these circumstances, the potential for lateral spreading at the subject site is considered low.

Seismically Induced Slope Instability
Seismically induced landslides and other slope failures are common occurrences during or soon after earthquakes. The project site topography has relatively flat ground conditions. In the absence of significant ground slopes, the potential for seismically induced landslides to affect the proposed site is considered to be very low.

Earthquake-Induced Flooding
Review of National Flood Hazard Layer FIRMette prepared by FEMA, Map Number 06079C1601H, dated May 16, 2017 2008 from the FEMA Map Service Center Viewer, indicates that the site is in an area designated as Zone X, “area of minimal flood hazard”.

The project site is located approximately 9.5 miles downstream of the Lopez Dam which has a 51,000 acre-foot capacity. The dam is under the jurisdiction of the State of California

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Division of Safety of Dams. Lopez dam is slated for seismic improvements and is being maintained at approximately 83 percent of capacity until the seismic retrofit is completed.

Due to the distance of the subject site from large bodies of water and regional flood control structures, the potential for flooding at the subject site is considered low. The potential of earthquake induced flooding of the subject site is considered to be low.

Tsunami and Seiches
Tsunamis are seismic sea waves generated by fault displacement or major ground movement. Based on the location of the site from the Pacific Ocean (approximately 0.45 miles) and review of the San Luis Obispo County Tsunami Hazard Areas Map for emergency planning, dated 2021, the project site is located in a mapped tsunami hazard area as shown on Figure No. 7, Tsunami Hazard Map. Tsunamis do pose a potential hazard and should be considered in project design. Seiches are large waves generated in enclosed bodies of water in response to ground shaking. Based on site locations away from lakes, reservoirs, seiches pose a very low hazard.

9.0 EARTHWORK RECOMMENDATIONS

Earthwork recommendations for the project are presented in the following sections.

9.1 General

This section contains our general recommendations regarding earthwork, grading and trench backfill for the project. These recommendations are based on the results of our field exploration, laboratory tests, our experience with similar projects, and data evaluation as presented in the preceding sections. These recommendations may require modification by the geotechnical consultant based on observation of the actual field conditions during grading.

Prior to the start of construction, all existing underground utilities and appurtenances should be located at the project site. Such utilities should either be protected in-place or removed and replaced during construction as required by the project specifications. All excavations should be conducted in such a manner as not to cause loss of bearing and/or lateral support of existing utilities and structure (if any).

All debris, deleterious material, artificial fill and demolished materials should be removed from the site. All cars, trucks and RV vehicles should be removed and cleared from the project site prior to the start of grading. Potentially contaminated soils from fuel and oil leaks should be cleaned and removed from the project site.

The final bottom surfaces of all excavations should be observed and approved by the project geotechnical consultant prior to placing any fill. Based on these observations, localized areas may require remedial grading deeper than indicated herein. Therefore,

Note: Calculated using EZFRISK program Risk Engineering, version 8.07 For : Carollo
SITE SPECIFIC DESIGN RESPONSE SPECTRUM per ASCE 7-16 and 2019 CBC Central Coast Advanced Treatment Project
Grover Beach
Project Number:
21-31-323-01
Figure No.
6Converse Consultants
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01234
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PERIOD (sec)
Design Response Spectrum
Probabilistic MCE_R Spectrum
Deterministic Spectrum
80% of CBC Spectrum

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some variations in the depth and lateral extent of excavation recommended in this report should be anticipated.

Observations and field tests should be performed by the project soils consultant to confirm that the required degree of compaction has been obtained. Where compaction is less than that specified, additional compactive effort should be made with adjustment of the moisture content as necessary, until the specified compaction is obtained.

It should be the responsibility of the contractor to maintain safe working conditions during all phases of construction.

9.2 Remedial Grading

Concrete pad should be uniformly supported by compacted fill. In order to provide uniform support, structural areas should be over-excavated, scarified, moisture conditioned, mixed and recompacted as follows.

Table No. 8, Over-excavation Depths
Structure/Pavement Minimum Excavation Depth
Concrete Pad at ground level 3 feet below pad bottom
Pump Station/ wells (Approximately 24 feet
below ground level)
1 foot below foundation bottom or 12 inches
scarifying and compaction
Pipelines Scarify to a depth of 6 inches below bottom of pipeline and compaction

The over-excavation should extend to at least 3 feet beyond the footprint of the concrete pad. The over-excavation bottom should be scarified and compacted as described in Section 9.5, Compacted Fill Placement.

If isolated pockets of very soft, loose, eroded, or pumping soil are encountered, the unstable soil should be excavated as needed to expose undisturbed, firm, and unyielding soils. The contractor should determine the best manner to conduct the excavations, such that there are no losses of bearing and/or lateral support to the existing structures or utilities (if any).

9.3 Over-excavation and Re-compaction

Footings founded on native soils (alluvium) should have at-least 3 feet of fill compacted below the bottom of footings and be compacted to at least 90 percent of the laboratory maximum dry density. All over-excavations should extend laterally at least 3 feet or equal to the depth of over-excavation, whichever is greater, outside the entire level portions of the building pad area.

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The final bottom surfaces of all excavations should be observed and approved by the project geotechnical consultant prior to placing any fill or structures. However, localized deeper over-excavation could be encountered, based on observations and testing by the geotechnical consultant during grading of the final bottom surfaces of all excavations.

If isolated pockets of very soft, loose, eroded, or pumping soil are encountered, the unstable soil should be excavated as needed to expose undisturbed, firm, and unyielding soils. The contractor should determine the best manner to conduct the excavations, such that there are no losses of bearing and/or lateral support to the existing structures or utilities (if any).

Areas to receive fill and/or other surface improvements should be scarified to a minimum depth of 6-inches, brought to a near-optimum moisture condition, and recompacted to at least 90 percent relative compaction (based on ASTM Test Method D1557).

9.4 Fill Materials

No fill should be placed until excavations and/or natural ground preparation have been observed by the geotechnical consultant. The native soils encountered within the project sites are generally considered suitable for re-use as compacted fill. Excavated soils should be processed, including removal of roots and debris, removal of oversized particles, mixing, and moisture conditioning, before placing as compacted fill. On-sites soils used as fill should meet the following criteria.

 No particles larger than 6 inches in largest dimension.  Rocks larger than 6 inches should be reduced in size or removed from areas to be graded.
 Rocks larger than one inch should not be placed within the upper 12 inches of subgrade soils.
 Free of all organic matter, debris, or other deleterious material.  Expansion index of 20 or less.
 Sand Equivalent greater than 15 (greater than 30 for pipe bedding).  Contain less than 30 percent by weight retained in 3/4-inch sieve.  Contain less than 40 percent fines (passing #200 sieve).

Based on field investigation and laboratory testing results, clean on-site soils may be suitable as fill materials.

Imported materials, if required, should meet the above criteria prior to being used as compacted fill. Any imported fills should be tested and approved by geotechnical representative prior to delivery to the sites.

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9.5 Compacted Fill Placement

All surfaces to receive structural fills should be scarified to a depth of at least 6 inches.

The soil should be moisture conditioned to within ±3 percent of optimum moisture content for coarse soils and 0 to 3 percent above optimum moisture content for fine soils. The scarified soils should be mixed and recompacted to at least 90 percent of the laboratory maximum dry density.

Fill soils should be mixed thoroughly, and moisture conditioned to within ±3 percent of optimum moisture content for coarse soils and 0 to 3 percent above optimum moisture content for fine soils. Fill soils should be evenly spread in horizontal lifts not exceeding 8- inches in uncompacted thickness.

All fill placed at the sites should be compacted to at least 90 percent of the laboratory maximum dry densities as determined by ASTM Standard D1557 test method unless a higher compaction is specified herein.

Fill materials should not be placed, spread or compacted during unfavorable weather conditions. When sites grading is interrupted by heavy rain, filling operations should not resume until the geotechnical consultant approves the moisture and density conditions of the previously placed fill.

9.6 Site Drainage

Adequate positive drainage should be provided away from the site and excavation areas to prevent ponding and to reduce percolation of water into the foundation soils. Surface drainage should be directed to suitable non-erosive devices.

9.7 Utility Trench Backfill

The following sections present earthwork recommendations for utility trench backfill, including subgrade preparation and trench zone backfill.

Open cuts adjacent to existing roadways or structures are not recommended within a 1:1 (horizontal:vertical) plane extending down and away from the roadway or structure perimeter (if any).

Soils from the trench excavation should not be stockpiled more than 6 feet in height or within a horizontal distance from the trench edge equal to the depth of the trench. Soils should not be stockpiled behind the shoring, if any, within a horizontal distance equal to the depth of the trench, unless the shoring has been designed for such loads.

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9.7.1 Pipeline Subgrade Preparation

The final subgrade surface should be level, firm, uniform, and free of loose materials and properly graded to provide uniform bearing and support to the entire section of the pipe placed on bedding material. Protruding oversize particles larger than 2 inches in dimension, if any, should be removed from the trench bottom and replaced with compacted on-site materials.

Any loose, soft and/or unsuitable materials encountered at the pipe subgrade should be removed and replaced with an adequate bedding material. During the digging of depressions for proper sealing of the pipe joints, the pipe should rest on a prepared bottom for as near its full length as is practicable.

9.7.2 Pipe Bedding

Bedding is defined as the material supporting and surrounding the pipe to 1 foot above the pipe. Recommendations for pipe bedding are provided below.

To provide uniform and firm support for the pipe, compacted granular materials such as clean sand, gravel or ¾-inch crushed aggregate, or crushed rock may be used as pipe bedding material. Typically, soils with sand equivalent value of 30 or more are used as pipe bedding material. The pipe designer should determine if the soils are suitable as pipe bedding material.

The type and thickness of the granular bedding placed underneath and around the pipe, if any, should be selected by the pipe designer. The load on the rigid pipes and deflection of flexible pipes and, hence, the pipe design, depends on the type and the amount of bedding placed underneath and around the pipe.

Bedding materials should be vibrated in-place to achieve compaction. Care should be taken to densify the bedding material below the springline of the pipe. Prior to placing the pipe bedding material, the pipe subgrade should be uniform and properly graded to provide uniform bearing and support to the entire section of the pipe placed on bedding material. During the digging of depressions for proper sealing of the pipe joints, the pipe should rest on a prepared bottom for as near its full length as is practicable.

Migration of fines from the surrounding native and/or fill soils must be considered in selecting the gradation of any imported bedding material. We recommend that the pipe bedding material should satisfy the following criteria to protect migration of fine materials.

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i. 𝐷𝐷15(𝐹𝐹)𝐷𝐷85(𝐵𝐵)≤5
ii. 𝐷𝐷50(𝐹𝐹)𝐷𝐷50(𝐵𝐵)<25
iii. Bedding Materials must have less than 5 percent passing No. 200 sieve (0.0074 mm) to avoid internal movement of fines.

Where,

F = Bedding Material
B = Surrounding Native and/or Fill Soils
D15(F) = Particle size through which 15% of bedding material will pass D85(B) = Particle size through which 85% of surrounding soil will pass D50(F) = Particle size through which 50% of bedding material will pass D50(B) = Particle size through which 50% of surrounding soil will pass

If the above criteria do not satisfy, commercially available geofabric used for filtration purposes (such as Mirafi 140N or equivalent) may be wrapped around the bedding material encasing the pipe to separate the bedding material from the surrounding native or fill soils.

9.7.3 Trench Zone Backfill

The trench zone is defined as the portion of the trench above the pipe bedding extending up to the final grade level of the trench surface. Excavated site soil free of oversize particles and deleterious matter may be used to backfill the trench zone. Detailed trench backfill recommendations are provided below.

 Trench excavations to receive backfill should be free of trash, debris or other unsatisfactory materials at the time of backfill placement.  Trench zone backfill should be compacted to at least 90 percent of the laboratory maximum dry density as per ASTM D1557 test method. At least the upper 1 foot of trench backfill underlying pavement should be compacted to at least 95 percent of the laboratory maximum dry density as per ASTM D1557 test method.  Particles larger than 1 inch should not be placed within 12 inches of the pavement subgrade. No more than 30 percent of the backfill volume should be larger than ¾-inch in the largest dimension. Gravel should be well mixed with finer soil. Rocks larger than 3 inches in the largest dimension should not be placed as trench backfill.
 Trench backfill should be compacted by mechanical methods, such as sheepsfoot, vibrating or pneumatic rollers or mechanical tampers to achieve the density specified herein. The backfill materials should be brought to within ± 3 percent of optimum moisture content for coarse-grained soil, and between optimum and 2 percent above optimum for fine-grained soil, then placed in horizontal layers. The

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thickness of uncompacted layers should not exceed 8 inches. Each layer should be evenly spread, moistened or dried as necessary, and then tamped or rolled until the specified density has been achieved.
 The contractor should select the equipment and processes to be used to achieve the specified density without damage to adjacent ground, structures, utilities and completed work.
 The field density of the compacted soil should be measured by the ASTM D1556 (Sand Cone) or ASTM D6938 (Nuclear Gauge) or equivalent.  Trench backfill should not be placed, spread or rolled during unfavorable weather conditions. When the work is interrupted by heavy rain, fill operations should not resume until field tests by the project’s geotechnical consultant indicate that the moisture content and density of the fill are in compliance with project specifications.

10.0 DESIGN RECOMMENDATIONS

The various design recommendations provided in this section are based on the assumption that the above earthwork and grading recommendations will be implemented in the project design and construction.

Where pipes are connecting to basins or between underground pipes, we recommend flexible connections should be considered to withstand piping movements during a credible seismic event. Buoyancy force should be considered in the design of the structures below water table.

10.1 Shallow Foundation Design Parameters

The design of the shallow foundations should be based on the recommended parameters presented in the table below.

Table No. 9, Recommended Foundation Parameters
Parameter Value
Minimum Isolated footing width 24 inches
Minimum continuous footing width 18 inches
Minimum Isolated or continuous footing depth of embedment below lowest adjacent grade 18 inches
Allowable net bearing capacity 2,000 psf

The actual footing dimensions and reinforcement should be based on structural design.

The allowable bearing capacity can be increased by 250 pounds per square foot (psf) with each foot of additional embedment and 250 psf with each foot of additional width up to a maximum of 3,000 psf.

The net allowable bearing values indicated above are for the dead loads and frequently applied live loads and are obtained by applying a factor of safety of 3.0 to the net ultimate

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bearing capacity. If normal code requirements are applied for design, the above vertical bearing value may be increased by 33 percent for short duration loadings, which will include loadings induced by wind or seismic forces.

10.2 Mat Foundation Design Parameters

The proposed concrete pad may be designed as mat foundation. The modulus of subgrade reaction (k) for design of flexible mat foundation was estimated from the available soil compressibility data and published charts. For design of flexible mat foundation, the following equation may be used.

k= k1[(B+1)/2B]2

Where,

k= vertical modulus of subgrade reaction for mat foundation, kips per cubic feet k1= 125 kcf, normalized modulus of subgrade reaction for 1-square-foot footing B= foundation width, feet

Other necessary parameters (modulus of elasticity and Poisson’s ratio) for mat foundation design are as follows.

E= 33 Wc1.5 fc 0.5 psi

Where,

Wc = weight of concrete (pcf)
fc = compressive strength of concrete at 28 days (psi)
ν = 0.35, Poisson’s Ratio

An allowable net bearing capacity of 3,000 psf may be used for mat foundations founded on compacted native soil. The mat should be reinforced with top and bottom steel, as appropriate, to provide structural continuity and to permit spanning of local irregularities.

The mat foundation dimensions, and reinforcement should be based on structural design.

For design purposes, the self-weight of the mat foundation can be negligible.

10.3 Lateral Earth Pressures and Resistance to Lateral Loads

In the following subsections, the lateral earth pressures and resistance to lateral loads are estimated by using on-site native soils strength parameters obtained from laboratory testing.

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10.3.1 Active Earth Pressures

The active earth pressure behind any buried wall or foundation depends primarily on the allowable wall movement, type of backfill materials, backfill slopes, wall or foundation inclination, surcharges, and any hydrostatic pressures. The lateral earth pressures are presented in the following tables.

Table No. 10, Active and At-Rest Earth Pressures
Loading Conditions Lateral Earth Pressure
(psf)
Active earth conditions (wall is free to deflect at least 0.001 radian) 35 At-rest (wall is restrained) 55

These pressures assume a level ground surface around the structure for a distance greater than the structure height, no surcharge, and no hydrostatic pressure.

If water pressure is allowed to build up behind the walls, the active pressures should be reduced by 50 percent and added to a full hydrostatic pressure to compute the design pressures against the walls. Cantilever retaining walls greater than 6 feet, as measured from the surface, should be designed to resist additional earth pressure caused by seismic ground shaking. A dynamic earth pressure of 26H (psf), based on an inverted triangular distribution, can be used for design of wall.

10.3.2 Passive Earth Pressure

Resistance to lateral loads can be assumed to be provided by a combination of friction acting at the base of foundations and by passive earth pressure. A coefficient of friction of 0.3 between formed concrete and soil may be used with the dead load forces. An allowable passive earth pressure of 200 psf per foot of depth may be used for the sides of the footing poured against recompacted native soils. A factor of safety of 1.5 was applied in calculating passive earth pressure. The maximum value of the passive earth pressure should be limited to 2,000 psf.

Vertical and lateral bearing values indicated above are for the total dead loads and frequently applied live loads. If normal code requirements are applied for design, the above vertical bearing and lateral resistance values may be increased by 33 percent for short duration loading, which will include the effect of wind or seismic forces.

Due to the low overburden stress of the soil at shallow depth, the upper 1 foot of passive resistance should be neglected unless the soil is confined by pavement or slab.

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10.4 Settlement

The total settlement of shallow footings from static structural loads and short-term settlement of properly compacted fill is anticipated to be 1 inch or less. The differential settlement resulting from static loads is anticipated to be 0.5 inches or less over a horizontal distance of 30 feet.

Based on our liquefaction analyses, liquefaction settlement is 0.6 inches for the subject site. Dry sand settlement is negligible. The differential settlement resulting from dynamic loads is anticipated to be 0.3 inch or less over a horizontal distance of 30 feet.

If the proposed development will be constructed 20 feet below ground level, then liquefaction settlement can be negligible.

Generally, the static and dynamic settlement does not occur at the same time. For design purposes, the structural engineer should decide whether static and dynamic settlement will be combined or not.

10.5 Soil Parameters for Pipe Design

Structural design requires proper evaluation of all possible loads acting on pipes and structures. The stresses and strains induced on buried pipes and walls depend on many factors, including the type of soil, density, bearing pressure, angle of internal friction, coefficient of passive earth pressure, and coefficient of friction at the interface between the backfill and native soils. The recommended values of the various soil parameters for design are provided in the following table.

Table No. 11, Soil Parameters for Pipe Design
Soil Parameters Value
Average compacted fill total unit weight, γ (pcf) 120
Angle of internal friction of soils, φ 32
Soil cohesion, c (psf) 100
Coefficient of friction between concrete and native soils, fs 0.3 Coefficient of friction between PVC pipe and native soils, fs 0.25 Bearing pressure against native soils (psf) 2,000
Coefficient of passive earth pressure, Kp 3.12
Coefficient of active earth pressure, Ka 0.32
Modulus of Soil Reaction E’ (psi) 1,500

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10.6 Bearing Pressure for Anchor and Thrust Blocks

An allowable net bearing pressure presented in Table No. 11, Soil Parameters for Pipe Design may be used for anchor and thrust block design against alluvial soils. Such thrust blocks should be at least 18 inches wide.

The allowable net bearing capacity is defined as the maximum allowable net bearing pressure on the ground. It is obtained by dividing the net ultimate bearing capacity by a safety factor. The ultimate bearing capacity is the bearing stress at which ground fails by shear or experiences a limiting amount of settlement at the foundation. The net ultimate bearing capacity is obtained by subtracting the total overburden pressure on a horizontal plane at the foundation level from the ultimate bearing capacity.

If normal code requirements are applied for design, the above recommended bearing capacity and passive resistances may be increased by 33 percent for short duration loading such as seismic or wind loading.

10.7 Soil Corrosivity

One representative soil sample was evaluated for corrosivity with respect to common construction materials such as concrete and steel. The test result is presented in Appendix B, Laboratory Testing Program and design recommendations pertaining to soil corrosivity are presented below.

The sulfate contents of the sampled soils correspond to American Concrete Institute (ACI) exposure category S0 for these sulfate concentrations (ACI 318-14, Table 19.3.1.1). No concrete type restrictions are specified for exposure category S0 (ACI 318-14, Table

19.3.2.1). A minimum compressive strength of 2,500 psi is recommended.

We anticipate that concrete structures such as footings, slab, and concrete pad will be exposed to moisture from precipitation and irrigation. Based on the site locations and the results of chloride testing of the site soils, we do not anticipate that concrete structures will be exposed to external sources of chlorides, such as deicing chemicals, salt, brackish water, or seawater. ACI specifies exposure category C1 where concrete is exposed to moisture, but not to external sources of chlorides (ACI 318-14, Table 19.3.1.1). ACI provides concrete design recommendations in ACI 318-14, Table 19.3.2.1, including a compressive strength of at least 2,500 psi and a maximum chloride content of 0.3 percent.

According to Romanoff, 1957, the following table provides general guideline of soil corrosion based on electrical resistivity.

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Table No. 12, Correlation Between Resistivity and Corrosion Soil Resistivity (ohm-cm) per Caltrans CT 643 Corrosivity Category Over 10,000 Mildly corrosive
2,000 – 10,000 Moderately corrosive
1,000 – 2,000 corrosive
Less than 1,000 Severe corrosive

The measured value of the minimum electrical resistivity of the sample when saturated was 12,225 ohm-cm for the site. This indicates that the soil tested is mildly corrosive to ferrous metals in contact with the soil. The site is in a coastal marine environment.

Converse does not practice in the area of corrosion consulting. If needed, a qualified corrosion consultant should provide appropriate corrosion mitigation measures for any ferrous metals in contact with the site soils.

10.8 Flexible Pavement

The flexible pavement structural section design recommendations were performed in accordance with the method contained in the CALTRANS Highway Design Manual, Chapter 630 without the factor of safety. No specific traffic study was performed to determine the Traffic Index (TI) for the proposed project; therefore, a wide range of TI values were evaluated.

Due to various earth materials encountered at the site, flexible pavement structural section recommendations are prepared for subgrade soils with the design R-value of 50.

We recommend that the project structural engineer consider the traffic loading conditions at various locations and select the appropriate pavement sections from the following table:

Table No. 13, Flexible Pavement Structural Sections
Design
R-value Design TI
Asphalt Concrete (AC) Over Aggregate Base (AB)
Structural Sections
Full AC
Structural
Section
AC (inches) AB (inches) AC (inches)
67*

4.0 3.0 3.0 4.0

5.0 3.0 4.0 4.5

6.0 4.0 4.0 5.0

7.0 4.0 4.5 6.5

8.0 5.0 5.0 7.5

9.0 6.0 6.0 9.0
*Design recommendations are based on R-Value of 50

Base material shall conform to requirements for Crushed Miscellaneous Base (CMB) or equivalent and should be placed in accordance with the requirements of the Standard

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Specifications for Public Works Construction (SSPWC, latest Edition). Asphaltic materials should conform to Section 203-1, "Paving Asphalt," of the Standard Specifications for Public Works Construction (SSPWC, latest Edition) and should be placed in accordance with Section 302-5, "Asphalt Concrete Pavement," of the SSPWC, 2018 edition.

Positive drainage should be provided away from all pavement areas to prevent seepage of surface and/or subsurface water into the pavement base and/or subgrade.

10.9 Rigid Pavement

Rigid pavement design recommendations were provided in accordance with the Portland Cement Association’s (PCA) Southwest Region Publication P-14, Portland Cement Concrete Pavement (PCCP) for Light, Medium and Heavy Traffic Rigid Pavement. We recommend that the project structural engineer consider the loading conditions at various locations and select the appropriate pavement sections from the following table:

Table No. 14, Rigid Pavement Structural Sections
Design R-Value Design
Traffic Index (TI)
PCCP Pavement Section
(inches)
67*

4.0 6.0

5.0 6.5

6.0 6.5

7.0 7.0

8.0 7.5

9.0 8.0
*Design recommendations are based on R-Value of 50

The above pavement section is based on a minimum 28-day Modulus of Rupture (M-R) of 550 psi and a compressive strength of 3,000 psi. The third point method of testing beams should be used to evaluate modulus of rupture. The concrete mix design should contain a minimum cement content of 5.5 sacks per cubic yard. Recommended maximum and minimum values of slump for pavement concrete are three inches to one inch, respectively.

Transverse contraction joints should not be spaced more than 10 feet and should be cut to a depth of 1/4 the thickness of the slab. Longitudinal joints should not be spaced more than 12 feet apart. A longitudinal joint is not necessary in the pavement adjacent to the curb and gutter section.

Prior to placement of concrete, at least the upper 12 inches of subgrade soils below rigid pavement sections should be compacted to at least 95 percent relative compaction as defined by the ASTM D 1557 standard test method.

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Positive drainage should be provided away from all pavement areas to prevent seepage of surface and/or subsurface water into pavement base and/or subgrade.

11.0 CONSTRUCTION RECOMMENDATIONS

Dewatering may be needed for wet well construction below water table.

Temporary sloped excavation and shoring design recommendations are presented in the following sections.

11.1 General

Prior to the start of construction, all existing underground utilities should be located at the project site. Such utilities should either be protected in-place or removed and replaced during construction as required by the project specifications.

Vertical braced excavations can be considered for the foundations. Sloped excavations may not be feasible in locations adjacent to existing utilities, pavement, or structures.

Recommendations pertaining to temporary excavations are presented in this section.

Excavations near existing structures may require vertical side wall excavation. Where the side of the excavation is a vertical cut, it should be adequately supported by temporary shoring to protect workers and any adjacent structures.

All applicable requirements of the California Construction and General Industry Safety Orders, the Occupational Safety and Health Act, and the Construction Safety Act should be met. The soils exposed in cuts should be observed during excavation by the geotechnical consultant and the competent person designated by the contractor. If potentially unstable soil conditions are encountered, modifications of slope ratios for temporary cuts may be required. Design team should consider buoyancy force.

Since ground water encountered approximately 11 feet below ground level and proposed structures may be constructed below 10 feet below ground level, dewatering will be required during construction.

11.2 Temporary Sloped Excavations

Temporary open-cut trenches may be constructed with side slopes as recommended in the following table. Temporary cuts encountering soft and wet fine-grained soils; dry loose, cohesionless soils or loose fill from trench backfill may have to be constructed at a flatter gradient than presented below.

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Table No. 15, Slope Ratios for Temporary Excavations
Soil Type OSHA Soil Type Depth of Cut
(feet)
Recommended Maximum Slope
(Horizontal:Vertical)*
Silty Sand (SM) C 0-10 1.5:1
* Slope ratio assumed to be uniform from top to toe of slope.

For shallow excavations up to 4 feet bgs, excavation can be vertical. For steeper temporary construction slopes or deeper excavations, or unstable soil encountered during the excavation, shoring or trench shields should be provided by the contractor to protect the workers in the excavation.

Surfaces exposed in slope excavations should be kept moist but not saturated to retard raveling and sloughing during construction. Adequate provisions should be made to protect the slopes from erosion during periods of rainfall. Surcharge loads, including construction materials, should not be placed within 5 feet of the unsupported slope edge.

Stockpiled soils with a height higher than 6 feet will require greater distance from trench edges.

11.3 Slot Cut Recommendations

Temporary excavations during possible improvements should not extend below a 1:1 horizontal:vertical (H:V) plane extending beyond and down from the bottom of the existing foundations, utility lines or structures. The remedial grading excavations should not cause loss of bearing and/or lateral support for adjacent foundations, utilities or structures.

If remedial grading excavations extend below a 1:1 horizontal:vertical (H:V) plane extending beyond and down from the bottom of adjacent off-site utility lines or structure foundations, shoring or slot cutting shall be employed. The ABC slot cutting method for over-excavation could be a possible option as an alternative to shoring for excavation less than 8 feet in width and depth or with cohesive soils. In general, for structures it is not recommended for slot cutting if the height of excavation exceeds more than 8 feet or into sandy soils and with surcharging load. Backfill should be accomplished in the shortest period of time possible and in alternating sections.

11.4 Shoring Design

Temporary shoring will be required for the recommended excavation due to space limitations and property line boundaries and because of nearby existing structures or facilities and traffic loading. Temporary shoring may consist of the use of a trench box (where feasible), or conventional soldier piles and lagging. Shoring should ultimately be designed by a qualified structural engineer considering the recommendations below in their final design and others which are applicable.

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Drilled excavations for soldier piles, which are recommended to create the proposed 30-foot-high excavation, may require the use of drilling fluids to prevent caving and to maintain an opened hole for pile installation. Alternatively, soldier piles can be driven to desired depth.

11.4.1 Cantilevered Shoring

Cantilevered shoring systems may include soldier piles with lagging to maintain temporary support of vertical wall excavations. Shoring design must consider the support of adjacent underground utilities and/or structures and should consider the effects of shoring deflection on supported improvements. Due to sandy nature of on-site soils, some caving during the drilling of soldier-pile borings should be anticipated. A soldier pile system will require continuous lagging to control caving and sloughing in the excavation between soldier piles.

Temporary cantilevered shoring should be designed to resist a lateral earth pressure equivalent to a fluid density of 35 pounds per cubic foot (pcf) for non-surcharged condition.

This pressure is valid only for shoring retaining level ground. This equivalent fluid pressure is valid only for shoring supporting level ground.

In addition to the lateral earth pressure, surcharge pressures due to miscellaneous loads, such as soil stockpiles, vehicular traffic or construction equipment located adjacent to the shoring, should be included in the design of the shoring. A uniform lateral pressure of 100 psf should be included in the upper 10 feet of the shoring to account for normal vehicular and construction traffic within 10 feet of the trench excavation. Surcharge pressures from the existing structures should be added to the above earth pressures for surcharges within a horizontal distance less than or equal to the wall height. Surcharge coefficients of 50% of any uniform vertical surcharge should be added as a horizontal earth pressure for shoring design. All shoring should be designed and installed in accordance with state and federal safety regulations.

The minimum embedment depth for piles is ten (10) feet from the lowest adjacent grade into firm alluvium, below the bottom of the excavation. Vertical skin friction against soldier piles for may be taken as 200 psf. Fixity may be assumed at two (2) feet below the excavation into firm native alluvium or bedrock. For the design of soldier piles spaced at least 3.0 diameters on-center, the passive resistance of the soils adjacent to the piles may be assumed to be 200 psf per foot of embedment depth. Soldier pile members placed in drilled holes should be properly backfilled with a sand/cement slurry or lean concrete in order to develop the required passive resistance.

Caving soils should be anticipated between the piles. To limit local sloughing, caving soils can be supported by continuous lagging or guniting. The lagging between the soldier piles may consist of pressure-treated wood members or solid steel sheets. In our opinion, steel sheeting is expected to be more expedient than wood lagging to install. Although

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soldier piles and any bracing used should be designed for the full-anticipated earth pressures and surcharge pressures, the pressures on the lagging are less because of the effect of arching between the soldier piles. Accordingly, the lagging between the piles may be designed for a nominal pressure of up to a maximum of 350 psf. All lumber to be left in the ground should be treated in accordance with Section 204-2 of the "Standard Specifications for Public Works Construction" (Latest Edition).

11.4.2 Tie-Back Shoring

A tie-back soldier-pile shoring system may be used to maintain temporary support of deep vertical walled excavations. Braced or tied-back shoring, retaining a level ground surface, should be designed for a uniform pressure of 20H psf, where H is the height of the retained cut in feet.

Surcharge pressures should be added to this earth pressure for surcharges within a distance from the top of the shoring less than or equal to the shoring height. A surcharge coefficient of 50 percent of any uniform vertical surcharge should be added as a horizontal shoring pressure for braced shoring. A uniform lateral pressure of 100 psf should be included in the upper 10 feet of the shoring to account for normal vehicular and construction traffic within 10 feet of the trench excavation.

11.4.3 Tie-Backs

For design of tie-back shoring, it should be assumed that the potential wedge of failure is determined by a plane at 30 degrees from the vertical, through the bottom of the excavation. Tie-back anchors may be installed at angles of 15 to 40 degrees below a horizontal plane. Soil friction values, for estimating the allowable capacity of drilled friction anchors, may be computed using the following equation:

q = 40H ; q < 500 pounds-per-square-foot (psf)

where:

H = average depth of anchor below ground surface, shown on q = anchor surface area resistance, in psf (excluding tip),

Only the frictional resistance developed beyond the assumed failure plane should be included in the tie-back design for resisting lateral loads. After shoring/tie-back is no longer needed to support the excavation, stress should be carefully released and shoring system including tieback may be able to be left in place.

All shoring and tie-back should be designed by experienced California licensed Civil Engineer and installed by experienced contractors. Shoring/tie-back design should also

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be reviewed by a geotechnical consultant to verify the soil parameters used in the design are in conformance with geotechnical report.

All applicable requirements of the California Construction and General Industry Safety Orders, the Occupational Safety and Health Act of 1987 and current amendments, and the Construction Safety Act should be met. The soils exposed in cuts should be observed during excavation by a competent person employed by the contractor. If potentially unstable soil conditions are encountered, modifications of slope ratios for temporary cuts may be required.

It is recommended that Converse review plans and specifications for proposed shoring and that a Converse representative observes the installation of shoring. A licensed surveyor should be retained to establish monuments on shoring and the surrounding ground prior to excavation. Such monuments should be monitored for horizontal and vertical movement during construction. Results of the monitoring program should be provided immediately to the project Structural (shoring) Engineer and Converse for review and evaluation. Adjacent building elements should be photo-documented prior to construction.

12.0 GEOTECHNICAL SERVICES DURING CONSTRUCTION

The project geotechnical consultant should review plans and specifications as the project design progresses. Such review is necessary to identify design elements, assumptions, or new conditions which require revisions or additions to our geotechnical recommendations.

The project geotechnical consultant should be present to observe conditions during construction. Geotechnical observation and testing should be performed as needed to verify compliance with project specifications. Additional geotechnical recommendations may be required based on subsurface conditions encountered during construction.

13.0 CLOSURE

This report is prepared for the project described herein and is intended for use solely by Carollo engineers and their design team to assist in the design and construction of the proposed project. Our findings and recommendations were obtained in accordance with generally accepted professional principles practiced in geotechnical engineering. We make no other warranty, either expressed or implied.

Converse Consultants is not responsible or liable for any claims or damages associated with interpretation of available information provided to others. Field exploration identifies actual soil conditions only at those points where samples are taken, when they are taken.

Data derived through sampling and laboratory testing is extrapolated by Converse employees who render an opinion about the overall soil conditions. Actual conditions in

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areas not sampled may differ. In the event that changes to the project occur, or additional, relevant information about the project is brought to our attention, the recommendations contained in this report may not be valid unless these changes and additional relevant information are reviewed and the recommendations of this report are modified or verified in writing. In addition, the recommendations can only be finalized by observing actual subsurface conditions revealed during construction. Converse cannot be held responsible for misinterpretation or changes to our recommendations made by others during construction.

As the project evolves, continued consultation and construction monitoring by a qualified geotechnical consultant should be considered an extension of geotechnical investigation services performed to date. The geotechnical consultant should review plans and specifications to verify that the recommendations presented herein have been appropriately interpreted, and that the design assumptions used in this report are valid.

Where significant design changes occur, Converse may be required to augment or modify the recommendations presented herein. Subsurface conditions may differ in some locations from those encountered in the explorations, and may require additional analyses and, possibly, modified recommendations.

Design recommendations given in this report are based on the assumption that it will be implemented. Additional consultation may be prudent to interpret Converse's findings for contractors, or to possibly refine these recommendations based upon the review of the actual site conditions encountered during construction. If the scope of the project changes, if project completion is to be delayed, or if the report is to be used for another purpose, this office should be consulted.

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14.0 REFERENCES

AMERICAN CONCRETE INSTITUTE (ACI), 2014, Building Code Requirements for Structural Concrete (ACI 318-14) and Commentary, October 2014.

AMERICAN SOCIETY OF CIVIL ENGINEERS (ASCE), 2017, Minimum Design Loads for Buildings and Other Structures, SEI/ASCE Standard No. 7-16, dated 2017.

CALIFORNIA BUILDING STANDARDS COMMISSION (CBSC), 2019, California Building Code (CBC).

CALIFORNIA DEPARTMENT OF CONSERVATION, 2021, San Luis Obispo County Tsunami Hazard Areas map, Oceano Quadrangle area, California.

CALIFORNIA GEOLOGICAL SURVEY (CGS), 2007, Fault-Rupture Hazard Zones in California, Alquist- Priolo Earthquake Faulting Zoning Act with Index to Earthquake Fault Zone Maps, Special Publication 42, revised 2007.

CALIFORNIA STATE WATER RESOURCES CONTROL BOARD (SWRCB), 2020, GeoTracker database ( http://geotracker.waterboards.ca.gov/) , accessed on September 11, 2020.

CITY OF GROVER BEACH GENERAL PLAN, Safety Element, Adopted by City Council Resolution No. 00- 55, dated October 16, 2000.

DAS, B.M., 2011, Principles of Foundation Engineering, Seventh Edition, published by Global Engineering, 2011.

DIBBLE, THOMAS, Jr., 2017, Oceano Quadrangle Geologic Map.

ROMANOFF, MELVIN, 1957, Underground Corrosion, National Bureau of Standards Circular 579, dated April 1957.

U.S. DEPARTMENT OF THE NAVY, 1986, NAVFAC DM 7.01: Soil Mechanics, Naval Facilities Engineering Command, Alexandria, Virginia.

U.S. GEOLOGICAL SURVEY (USGS), 2020, National Water Information System: Web Interface ( http://nwis.waterdata.usga.gov/nwis/gwlevels) , accessed on September 11, 2020.

UNITED STATES GEOLOGIC SURVEY, 2018, Oceano Quadrangle Map

SPTLIQ (InfraGEO Software, 2019) program for liquefaction analyses.

STANDARD SPECIFICATIONS FOR PUBLIC WORKS CONSTRUCTION, Public Works Standards, Inc.

TOPPOZADA, T., et. al., 2000, Epicenters of and Areas Damaged by M≥5 California Earthquakes, 1800- 1999, Map Sheet 49, California Geologic Survey.

Appendix A

Field Exploration

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Grover Beach, California
June 14, 2022
Page A-1

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APPENDIX A: FIELD EXPLORATION

Our field investigation included site reconnaissance and a subsurface exploration program consisting of drilling soil borings. During the site reconnaissance, the surface conditions were noted, and the borings were marked within the footprint of the project area. The approximate boring locations were established in the field with reference to existing facilities in the streets, and other visible features. The locations should be considered accurate only to the degree implied by the method used.

Five exploratory borings (BH-1 to BH-5) were drilled on May 13, 2022, to investigate the subsurface conditions at the site. The borings were drilled to a maximum depth of 51.5 feet below existing ground surface (bgs). Additional borings were drilled at the subject project site and percolation tests were performed utilizing four borings PT-1, PT-2, PT-3 and PT-4, on July 6, 2022. Percolation test results are presented in Appendix D.

The borings were advanced using a truck-mounted drill rig equipped with 8-inch diameter hollow-stem augers for soils sampling. Encountered materials were continuously logged by a Converse engineer and classified in the field by visual classification in accordance with the Unified Soil Classification System. Where appropriate, the field descriptions and classifications have been modified to reflect laboratory test results.

Relatively undisturbed samples were obtained using California Modified Samplers (2.4 inches inside diameter and 3.0 inches outside diameter) lined with thin sample rings. The steel ring sampler was driven into the bottom of the borehole with successive drops of a 140-pound driving weight falling 30 inches. Blow counts at each sample interval are presented on the boring logs. Samples were retained in brass rings (2.4 inches inside diameter and 1.0 inch in height) and carefully sealed in waterproof plastic containers for shipment to the Converse laboratory. Bulk samples of typical soil types were also obtained.

The exact depths at which material changes occur cannot always be established accurately. Unless a more precise depth can be established by other means, changes in material conditions that occur between drive samples are indicated on the logs at the top of the next drive sample.

Following the completion of logging and sampling, the borings were backfilled with cement grout and compacted by pushing down with augers using the drill rig weight.

For a key to soil symbols and terminology used in the boring logs, refer to Drawing Nos.

A-1a through A-1b, Unified Soil Classification and Key to Boring Log Symbols. For logs of borings, see Drawing Nos. A-2 and A-6, Logs of Borings.

1 A-1a
Drawing No.Project No.
(LITTLE OR NO FINES)

INORGANIC SILTS AND VERY

FINE SANDS, ROCK FLOUR,

SILTY OR CLAYEY FINE

SANDS OR CLAYEY SILTS

WITH SLIGHT PLASTICITY

LIQUID LIMIT LESS
THAN 50

SILTY GRAVELS, GRAVEL - SAND
- SILT MIXTURES
OH
SC

SILTS AND
CLAYS
MORE THAN 50% OF

COARSE FRACTION
PASSING ON NO. 4
SIEVE
MORE THAN 50% OF

MATERIAL IS
LARGER THAN NO.
200 SIEVE SIZE

SILTY SANDS, SAND - SILT

MIXTURES

POORLY-GRADED SANDS,

GRAVELLY SAND, LITTLE OR

NO FINES
(LITTLE OR NO FINES)
OL

WELL-GRADED GRAVELS,

GRAVEL - SAND MIXTURES,

LITTLE OR NO FINES

SANDS WITH
FINES
CL

HIGHLY ORGANIC SOILS PT
MORE THAN 50% OF

MATERIAL IS
SMALLER THAN NO.
200 SIEVE SIZE
SM

WELL-GRADED SANDS,

GRAVELLY SANDS, LITTLE

OR NO FINES
(APPRECIABLE AMOUNT

OF FINES)
SP
SW
COARSE

GRAINED
SOILS

POORLY-GRADED GRAVELS,

GRAVEL - SAND MIXTURES,

LITTLE OR NO FINES

CLAYEY GRAVELS, GRAVEL -

SAND - CLAY MIXTURES

SAMPLE TYPE
LETTER

INORGANIC CLAYS OF LOW TO

MEDIUM PLASTICITY,

GRAVELLY CLAYS, SANDY

CLAYS, SILTY CLAYS, LEAN
CLAYS

ORGANIC CLAYS OF MEDIUM TO

HIGH PLASTICITY, ORGANIC
SILTS
SAND
AND
SANDY
SOILS

INORGANIC SILTS, MICACEOUS

OR DIATOMACEOUS FINE

SAND OR SILTY SOILS

SOIL CLASSIFICATION CHART
MORE THAN 50% OF

COARSE FRACTION
RETAINED ON NO. 4
SIEVE
(APPRECIABLE AMOUNT

OF FINES)
GC

DESCRIPTIONS

BORING LOG SYMBOLS
NOTE: DUAL SYMBOLS ARE USED TO INDICATE BORDERLINE SOIL CLASSIFICATIONS

ORGANIC SILTS AND ORGANIC

SILTY CLAYS OF LOW

PLASTICITY
FINE

GRAINED
SOILS

SILTS AND
CLAYS
ML

TYPICAL
Split barrel sampler in accordance withASTM D-1586-84 Standard Test Method No recovery

BULK SAMPLE

GROUNDWATER WHILE DRILLING

GROUNDWATER AFTER DRILLING
MH
GM
GW

SYMBOLS

PEAT, HUMUS, SWAMP SOILS

WITH HIGH ORGANIC

CONTENTS

LIQUID LIMIT
GREATER THAN 50

MAJOR DIVISIONS

STANDARD PENETRATION TEST
CH

GRAVELS
WITH
FINES
DRIVE SAMPLE 2.42" I.D. sampler (CMS).

DRIVE SAMPLE
CLEAN
SANDS
GRAVEL
AND

GRAVELLY
SOILS
CLEAN

GRAVELS

INORGANIC CLAYS OF HIGH

PLASTICITY
GP

CLAYEY SANDS, SAND - CLAY

MIXTURES
GRAPH
Converse Consultants

DRILLING METHOD SYMBOLS
C
CL
CP
CR
CU
DS
EI
M
OC
P
PA
PI
PL
PM
PP
R
SE
SG
SW
TV
UC
UU
UW

FIELD AND LABORATORY TESTS
Consolidation (ASTM D 2435)
Collapse Potential (ASTM D 4546)
Compaction Curve (ASTM D 1557)
Corrosion, Sulfates, Chlorides (CTM 643-99; 417; 422)
Consolidated Undrained Triaxial (ASTM D 4767)
Direct Shear (ASTM D 3080)
Expansion Index (ASTM D 4829)
Moisture Content (ASTM D 2216)
Organic Content (ASTM D 2974)
Permeablility (ASTM D 2434)
Particle Size Analysis (ASTM D 6913 [2002])
Liquid Limit, Plastic Limit, Plasticity Index
(ASTM D 4318)
Point Load Index (ASTM D 5731)
Pressure Meter
Pocket Penetrometer
R-Value (CTM 301)
Sand Equivalent (ASTM D 2419)
Specific Gravity (ASTM D 854)
Swell Potential (ASTM D 4546)
Pocket Torvane
Unconfined Compression - Soil (ASTM D 2166)
Unconfined Compression - Rock (ASTM D 7012)
Unconsolidated Undrained Triaxial (ASTM D 2850)
Unit Weight (ASTM D 2937)
Auger Drilling Mud Rotary Drilling Dynamic Coneor Hand Driven Diamond Core

SOIL CLASSIFICATION AND KEY TO BORING LOG SYMBOLS
Project Name:

Central Coast Blue Advanced
Water Treatment,
Grover Beach, California
For: CarolloProject ID: 206.GPJ; Template: LOG
21-31-323-01

CONSISTENCY OF COHESIVE SOILS
Descriptor
Very Soft
Soft
Medium Stiff
Stiff
Very Stiff
Hard

APPARENT DENSITY OF COHESIONLESS SOILS
Descriptor Criteria
Descriptor SPT N - Value (blows / foot)
Very Loose
Loose
Medium Dense
Dense
Very Dense
50 Nonplastic
Low
Medium
High
Descriptor Criteria
Crumbles or breaks with handling orlittle finger pressure.

Crumbles or breaks with considerable
finger pressure.

Will not crumble or break with fingerpressure.

Weak
Moderate
Strong
Unconfined Compressive Strength (tsf)Torvane (tsf)
Pocket Penetrometer (tsf)

4.0 Descriptor Criteria
Trace (fine)/
Few
Little
Some
Mostly
Particles are present but estimated
to be less than 5%
5 to 10%
15 to 25%
30 to 45%
50 to 100%

PERCENT OF PROPORTION OF SOILS

MOISTURE
Criteria
Absence of moisture, dusty, dry to the touch
Damp but no visible water
Visible free water, usually soil is belowwater table
Size
Coarse
MediumFine
> 12 inches
3 to 12 inches
Passing No. 200 Sieve
No. 10 Sieve to No. 4 Sieve
No. 40 Sieve to No. 10 SieveNo. 200 Sieve to No. No. 40 Sieve

4.0 60

PLASTICITY OF FINE-GRAINED SOILS
Descriptor
Dry
Moist
Wet
Boulder
Cobble
Gravel
Sand
Silt and Clay
Descriptor
Coarse
Fine
3/4 inch to 3 inches
No. 4 Sieve to 3/4 inch
CEMENTATION/ Induration
A 1/8-inch thread cannot be rolled at any water content.

The thread can barely be rolled, and the lump cannot be formed when drier than the plastic limit.

The thread is easy to roll, and not much time is required to reach the plastic limit; it cannot be rerolled after reaching the plastic limit. The lump crumbles when drier than the plastic limit.

It takes considerable time rolling and kneading to reach the plastic limit. The thread can be rerolled several timesafter reaching the plastic limit. The lump can be formed without crumbling when drier than the plastic limit.

Field Approximation
Easily penetrated several inches by fist
Easily penetrated several inches by thumb
Can be penetrated several inches by thumb
with moderate effort
Readily indented by thumb but penetratedonly with great effort Readily indented by thumbnail
Indented by thumbnail with difficulty

2.0 SOIL PARTICLE SIZE
NOTE: This legend sheet provides descriptions andassociated criteria for required soil description componentsonly. Refer to Caltrans Soil and Rock Logging, Classification,and Presentation Manual (2010), Section 2, for tables ofadditional soil description components and discussion of soildescription and identification.

A-1b
Drawing No.Project No.

Project ID: 206.GPJ; Template: LOG
Converse Consultants

SOIL CLASSIFICATION AND KEY TO BORING LOG SYMBOLS
Project Name:

Central Coast Blue Advanced
Water Treatment,
Grover Beach, California
For: Carollo
SPT Blow
Counts
30 CA
Sampler
50 CA Sampler
60 Scattered (coarse)
21-31-323-01

DS 3/3/4
16/17/40
14/20/30
8/17/28
13/50@5"
FILL (Af): SILTY SAND (SM): fine to medium-grained, moist, reddish-brown.

ALLUVIUM (Qal):

CLAYEY SAND (SC): alluvial deposits, dense, moist,
light brown to dark brown.
- Groundwater encountered at 11 feet during drilling
SILTY SAND (SM): fine to medium-grained, trace clay,
dense, wet, light brown to reddish brown.
- very dense, brown
End of boring at 30 feet below ground level.

Groundwater encountered at 11 feet below ground level.

Boring was backfilled with soil cuttings and compacted
on 5/13/2022.
96 102
108
114
7 10
18 20
BU
L
K
P.Ariram
Driving Weight and Drop:

Converse Consultants
Logged by:

This log is part of the report prepared by Converse for this project and should be read together with the report. This summary applies only atthe location of the boring and at the time of drilling. Subsurface conditions may differ at other locations and may change at thislocation with the passage of time. The data presented is a simplification of actual conditions encountered.
11 De
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SUMMARY OF SUBSURFACE CONDITIONS
Sivathasan
DR
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DR
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U
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SAMPLES
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21-31-323-01 A-2
Checked By:

Depth to Water (ft):

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Log of Boring No. BH-01

SUMMARY OF SUBSURFACE CONDITIONS
140 lbs / 30 in8" HOLLOW STEM AUGER
DR
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U
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(p
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Equipment:

Drawing No.
5 10
15 20
25 30
22 Dates Drilled:

MO
I
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E

(
%
)
5/13/2022
5 10
15 20
25 30
Project Name Project No.

Ground Surface Elevation (ft):

Central Coast Blue Advanced Water Treatment
972 Huber Street, Grover Beach, California
Converse Project No. 21-31-323-00 (01)
For: - Carollo
BL
O
W
S

/

6 "
Project ID: 323.GPJ; Template: LOG

PA
WA(fc=35%)
DS
WA(fc=26%)
6/8/11
11/8/11
14/21/25
10/11/12
14/15/16
12/33/50@6"
FILL (Af):

SILTY SAND (SM): fine to coarse-grained, moist,reddish brown.

ALLUVIUM (Qal):

SILTY SAND (SM): fine to coarse-grained, mediumdense, moist, reddish brown to brown. - Groundwater encountered at 13 feet during driling
dense, wet, brown
trace clay,
very dense, brown to light brown
101
100
110
106
4 6
17 22
BU
L
K
P.Ariram
Driving Weight and Drop:

Converse Consultants
Logged by:

This log is part of the report prepared by Converse for this projectand should be read together with the report. This summary appliesonly at the location of the boring and at the time of drilling.Subsurface conditions may differ at other locations and may changeat this location with the passage of time. The data presented is asimplification of actual conditions encountered. 13 De
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SUMMARY OF SUBSURFACE CONDITIONS
Sivathasan
DR
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DR
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SAMPLES
Gr
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21-31-323-01 A-3a
Checked By:

Depth to Water (ft):

De
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Log of Boring No. BH-02

SUMMARY OF SUBSURFACE CONDITIONS
140 lbs / 30 in8" HOLLOW STEM AUGER
DR
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U
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W
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(p
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f
)
DR
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Equipment:

Drawing No.
5 10
15 20
25 30
22 Dates Drilled:

MO
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(
%
)
5/13/2022
5 10
15 20
25 30
Project Name Project No.

Ground Surface Elevation (ft):

Central Coast Blue Advanced Water Treatment
972 Huber Street, Grover Beach, California
Converse Project No. 21-31-323-00 (01)
For: - Carollo
BL
O
W
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/

6 "
Project ID: 323.GPJ; Template: LOG

NoRecovery
WA(fc=27%)
WA(fc=28%)
12/18/21
8/12/12
19/12/20
19/25/50@6"
ALLUVIUM (Qal):

SILTY SAND (SM): fine to coarse-grained, dense, wet,brown.

End of boring at 51.5 feet below ground level.Groundwater encountered at 13 feet.Boring was backfilled with soil cuttings and compactedon 05/13/2022. 12118
BU
L
K
P.Ariram
Driving Weight and Drop:

Converse Consultants
Logged by:

This log is part of the report prepared by Converse for this projectand should be read together with the report. This summary appliesonly at the location of the boring and at the time of drilling.Subsurface conditions may differ at other locations and may changeat this location with the passage of time. The data presented is asimplification of actual conditions encountered. 13 De
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SUMMARY OF SUBSURFACE CONDITIONS
Sivathasan
DR
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DR
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U
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SAMPLES
Gr
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21-31-323-01 A-3b
Checked By:

Depth to Water (ft):

De
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Log of Boring No. BH-02

SUMMARY OF SUBSURFACE CONDITIONS
140 lbs / 30 in8" HOLLOW STEM AUGER
DR
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U
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(p
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Equipment:

Drawing No.
40 45
50 22
Dates Drilled:

MO
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U
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(
%
)
5/13/2022
40 45
50 Project Name Project No.

Ground Surface Elevation (ft):

Central Coast Blue Advanced Water Treatment
972 Huber Street, Grover Beach, California
Converse Project No. 21-31-323-00 (01)
For: - Carollo
BL
O
W
S

/

6 "
Project ID: 323.GPJ; Template: LOG

CR
C 10/7/10
6/9/9
6/9/12
6/14/19
FILL (Af):

SILTY SAND (SM): fine to coarse-grained, moist,reddish brown.

ALLUVIUM (Qal):

SILTY SAND (SM): fine to coarse-grained, rocks andcobbles, maximum dimension up to 2 inches, moist,reddish brown to light brown. - Groundwater encountered at 13.8 feet during drilling
wet, dark brown
End of boring at 21.5 feet below ground level.Groundwater encountered at 13.8 feet below groundlevel.Boring backfilled with soil cuttings and compacted on05/13/22. 100
107
5 12
BU
L
K
P.Ariram
Driving Weight and Drop:

Converse Consultants
Logged by:

This log is part of the report prepared by Converse for this projectand should be read together with the report. This summary appliesonly at the location of the boring and at the time of drilling.Subsurface conditions may differ at other locations and may changeat this location with the passage of time. The data presented is asimplification of actual conditions encountered.

13.8 De
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SUMMARY OF SUBSURFACE CONDITIONS
Sivathasan
DR
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DR
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U
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SAMPLES
Gr
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21-31-323-01 A-4
Checked By:

Depth to Water (ft):

De
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BU
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Log of Boring No. BH-03

SUMMARY OF SUBSURFACE CONDITIONS
140 lbs / 30 in8" HOLLOW STEM AUGER
DR
Y

U
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W
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(p
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DR
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Equipment:

Drawing No.
5 10
15 20
22 Dates Drilled:

MO
I
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U
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E

(
%
)
5/13/2022
5 10
15 20
Project Name Project No.

Ground Surface Elevation (ft):

Central Coast Blue Advanced Water Treatment
972 Huber Street, Grover Beach, California
Converse Project No. 21-31-323-00 (01)
For: - Carollo
BL
O
W
S

/

6 "
Project ID: 323.GPJ; Template: LOG

SE
9/9/11
5/10/17
FILL (Af):

SILTY SAND (SM): fine to coarse-grained, moist,reddish-brown.

ALLUVIUM (Qal):

SILTY SAND (SM): fine to coarse-grained, moist,brown.

End of boring at 11.5 feet below ground level.No ground water encountered.Boring backfilled with soil cuttings and compacted on05/13/2022. 1014
BU
L
K
P.Ariram
Driving Weight and Drop:

Converse Consultants
Logged by:

This log is part of the report prepared by Converse for this projectand should be read together with the report. This summary appliesonly at the location of the boring and at the time of drilling.Subsurface conditions may differ at other locations and may changeat this location with the passage of time. The data presented is asimplification of actual conditions encountered.

NOT ENCOUNTERED
De
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SUMMARY OF SUBSURFACE CONDITIONS
Sivathasan
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Gr
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21-31-323-01 A-5
Checked By:

Depth to Water (ft):

De
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BU
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Log of Boring No. BH-04

SUMMARY OF SUBSURFACE CONDITIONS
140 lbs / 30 in8" HOLLOW STEM AUGER
DR
Y

U
N
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W
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.
(p
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f
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DR
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Equipment:

Drawing No.
5 10
20 Dates Drilled:

MO
I
S
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U
R
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(
%
)
5/13/2022
5 10
Project Name Project No.

Ground Surface Elevation (ft):

Central Coast Blue Advanced Water Treatment
972 Huber Street, Grover Beach, California
Converse Project No. 21-31-323-00 (01)
For: - Carollo
BL
O
W
S

/

6 "
Project ID: 323.GPJ; Template: LOG

CP
9/11/7
4/2/2
FILL (Af):

SILTY SAND (SM): fine to coarse-grained, moist,reddish-brown.

ALLUVIUM (Qal):

SILTY SAND (SM): fine to medium-grained, moist,brown.

End of boring at 11.5 feet below ground level.No groundwater encountered.Boring backfilled with soil cuttings on 5/13/22. 1168
BU
L
K
P.Ariram
Driving Weight and Drop:

Converse Consultants
Logged by:

This log is part of the report prepared by Converse for this projectand should be read together with the report. This summary appliesonly at the location of the boring and at the time of drilling.Subsurface conditions may differ at other locations and may changeat this location with the passage of time. The data presented is asimplification of actual conditions encountered.

NOT ENCOUNTERED
De
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SUMMARY OF SUBSURFACE CONDITIONS
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21-31-323-01 A-6
Checked By:

Depth to Water (ft):

De
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BU
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Log of Boring No. BH-05

SUMMARY OF SUBSURFACE CONDITIONS
140 lbs / 30 in8" HOLLOW STEM AUGER
DR
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U
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W
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(p
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DR
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Equipment:

Drawing No.
5 10
20 Dates Drilled:

MO
I
S
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U
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(
%
)
5/13/2022
5 10
Project Name Project No.

Ground Surface Elevation (ft):

Central Coast Blue Advanced Water Treatment
972 Huber Street, Grover Beach, California
Converse Project No. 21-31-323-00 (01)
For: - Carollo
BL
O
W
S

/

6 "
Project ID: 323.GPJ; Template: LOG

Appendix B

Laboratory Testing Program

Geotechnical Investigation Report
Central Coast Blue Advanced Water Treatment Project
Grover Beach, California
June 14, 2022
Page B-1

Converse Consultants
K:\31-Geotech\2021\21-31-323, Carollo, Central Coast Blue Advanced Water Treatment\Report\21-31-323 GIR (01) Grover Beach 6-15-22 FINAL.docx

APPENDIX B: LABORATORY TESTING PROGRAM

Tests were conducted in our laboratory on representative soil samples for the purpose of classification and evaluation of their physical properties and engineering characteristics.

The amount and selection of tests were based on the geotechnical parameters required for this project. Test results are presented herein and on the Logs of Borings, in Appendix A, Field Exploration. The following is a summary of the various laboratory tests conducted for this project.

In-Situ Moisture Content and Dry Density

In-situ dry density and moisture content tests were performed on relatively undisturbed ring samples, in accordance with ASTM Standard D2216 and D2937 to aid soils classification and to provide qualitative information on strength and compressibility characteristics of the site soils. For test results, see the Logs of Borings in Appendix A, Field Exploration.

Sand Equivalent

One representative bulk sample was tested to evaluate the expansion potential in accordance with ASTM Standard D2419. The test results are presented in the following table.

Table No. B-1, Summary of Sand Equivalent Test Results
Boring No. Depth
(feet) Soil Description Sand Equivalent
BH-4 10.0 – 11.5 Silty Sand (SM) 24

Soil Corrosivity

One representative soil sample was tested to determine minimum electrical resistivity, pH, and chemical content, including soluble sulfate and chloride concentrations. The purpose of these tests was to determine the corrosion potential of site soils when placed in contact with common construction materials. The test was performed by AP Engineers. (Pomona, CA) in accordance with Caltrans Test Methods 643, 422 and 417. Test result was presented in the following table.

Table No. B-2, Summary of Soil Corrosivity Test Results Boring
No.

Depth
(feet) pH
Soluble Sulfates
(CA 417)
(ppm)
Soluble
Chlorides
(CA 422) (ppm)
Min. Resistivity
(CA 643)
(Ohm-cm)
BH-3 1-5 8.1 26 21 12,225

Geotechnical Investigation Report
Central Coast Blue Advanced Water Treatment Project
Grover Beach, California
June 14, 2022
Page B-2

Converse Consultants
K:\31-Geotech\2021\21-31-323, Carollo, Central Coast Blue Advanced Water Treatment\Report\21-31-323 GIR (01) Grover Beach 6-15-22 FINAL.docx

R-Value

One representative bulk soil sample was tested for resistance value (R-value) in accordance with California Test Method CT301. This test is designed to provide a relative measure of soil strength for use in pavement design. The test result is presented in the table below.

Table No. B-3, Summary of R-Value Test Result
Boring No. Depth (feet) Soil Classification Measured R-Value PT-1 0-4 Silty Sand (SM) 67

Percent Finer Than Sieve No. 200

The percent finer than sieve No. 200 tests were performed on four (4) selected soil samples to aid in the classification of the on-site soils and to estimate other engineering parameters. Testing was performed in general accordance with the ASTM Standard D1140 test method. The test results are presented in the boring logs.

Table No. B-4, Summary of Percent Passing Sieve #200 Test Results Boring No. Depth
(feet) Soil Classification Percent Passing Sieve No. 200 BH-2 20 Silty Sand (SM) 35
BH-2 30 Silty Sand (SM) 26
BH-2 40 Silty Sand (SM) 27
BH-2 50 Silty Sand (SM) 28

Grain-Size Analyses

To assist in classification of soils, mechanical grain-size analysis was performed on one selected samples in accordance with the ASTM Standard D6913 test method. Grain-size curves are shown in Drawing No. B-1, Grain Size Distribution Results and results are presented in the below table.

Table No. B-5, Summary of Grain Size Distribution Test Results Boring No. Depth
(feet) Soil Classification % Gravel % Sand %Silt %Clay
BH-2 0-5 Silty Sand (SM) 6.0 67.0 27.0

Maximum Density and Optimum Moisture Content

Laboratory maximum dry density-optimum moisture content relationship test was performed on one representative bulk sample. The test was conducted in accordance with the ASTM Standard D1557 test method. The test results are presented in Drawing

Geotechnical Investigation Report
Central Coast Blue Advanced Water Treatment Project
Grover Beach, California
June 14, 2022
Page B-3

Converse Consultants
K:\31-Geotech\2021\21-31-323, Carollo, Central Coast Blue Advanced Water Treatment\Report\21-31-323 GIR (01) Grover Beach 6-15-22 FINAL.docx

No. B-2, Moisture-Density Relationship Results, and are summarized in the following table.

Table No. B-6, Summary of Moisture-Density Relationship Results Boring
No.

Depth
(feet) Soil Description Optimum Moisture
(%)
Maximum Density
(lb/cft)
BH-5 0-5 Silty Sand (SM) 8.0 122.5

Consolidation Test

Consolidation test was performed on one (1) selected sample as per ASTM Standard D2435. Data obtained from this test performed on relatively undisturbed soil sample was used to evaluate the settlement characteristics of the foundation soils under load.

Preparation for this test involved trimming the sample and placing the one-inch high brass ring into the test apparatus, which contained porous stones, both top and bottom, to accommodate drainage during testing. Normal axial loads were applied to one end of the sample through the porous stones, and the resulting deflections were recorded at various time periods. The load was increased after the sample reached a reasonable state of equilibrium. Normal loads were applied at a constant load-increment ratio, successive loads being generally twice the preceding load. The sample was tested at field and submerged conditions. The test results, including sample density and moisture content, are presented in Drawing No. B-3, Consolidation Test Results.

Direct Shear

Two direct shear tests were performed on relatively undisturbed representative ring samples under soaked moisture condition in accordance with the ASTM D3080 procedure. For each test, three samples contained in brass sampler rings were placed, one at a time, directly into the test apparatus and subjected to a range of normal loads appropriate for the anticipated conditions. The samples were then sheared at a constant strain rate of 0.02 inch/minute. Shear deformation was recorded until a maximum of about

0.25-inch shear displacement was achieved. Ultimate strength was selected from the shear-stress deformation data and plotted to determine the shear strength parameters.

For test data, including sample density and moisture content, see Drawings Nos. B-4a and B-4b, Direct Shear Test Results, and the following table.

Table No. B-7, Summary of Direct Shear Test Results
Boring No. Depth
(feet) Soil Description
Ultimate Strength Parameters
Friction Angle
(degrees)
Cohesion
(psf)
BH-1 5.0-6.5 Silty Sand (SM) 32 100
BH-2 25.0-26.5 Silty Sand (SM) 30 50

Geotechnical Investigation Report
Central Coast Blue Advanced Water Treatment Project
Grover Beach, California
June 14, 2022
Page B-4

Converse Consultants
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Sample Storage

Soil samples presently stored in our laboratory will be discarded 30 days after the date of this report, unless this office receives a specific request to retain the samples for a longer period.

0 5
10 15
20 25
30 35
40 45
50 55
60 65
70 75
80 85
90 95
100

0.0010.010.1110100
30 40 50

Depth (ft)
Depth (ft)
3 0.197
6 67.0
Boring No.
603

GRAIN SIZE DISTRIBUTION RESULTS
B-1
PL

0.09 Boring No.

27.0 Silty Sand (SM)
Drawing No.
0-5
PE
R
C
E
N
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F
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B
Y

W
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100 140

COBBLES SAND
2 LL
medium
GRAVEL
4 14
D10

SILT OR CLAY
84 0-5

1.5 1/2
Cc
fine
16 %ClayD100 D60
HYDROMETERU.S. SIEVE OPENING IN INCHES
coarse

6.019
1 %Gravel %Silt
10 Project No.
20 Description

D30
fine

GRAIN SIZE IN MILLIMETERS
CuPI
200
coarse
6 3/4
%Sand
U.S. SIEVE NUMBERS
3/8
Project Name
Central Coast Blue Advanced Water Treatment
972 Huber Street, Grover Beach, California
Converse Project No. 21-31-323-00 (01)
For: - Carollo
21-31-323-01
BH-2
BH-2
Converse Consultants
Project ID: 323.GPJ; Template: GRAIN SIZE

90 95
100
105
110
115
120
125
130
135
140
145
150
0 5 10 15 20 25 30
MAXIMUM DRYDENSITY, pcfSYMBOL
811.5 122.5
DEPTH (ft)
DR
Y

D
E
N
S
I
T
Y
,

p
c
f
BORING NO.DESCRIPTION ASTMTEST METHOD
D1557 Method D
Curves of 100% Saturationfor Specific Gravity Equal to:

OPTIMUMWATER, %
BH -05

MOISTURE-DENSITY RELATIONSHIP RESULTS

SILTY SAND (SM)

2.802.702.60
WATER CONTENT, %
Project Name
Central Coast Blue Advanced Water Treatment
972 Huber Street, Grover Beach, California
Converse Project No. 21-31-323-00 (01)
For: - Carollo
Project No. Drawing No.
21-31-323-01 B-2Converse Consultants
Project ID: 323.GPJ; Template: COMPACTION

0 2
4 6
8 100.1 1 10 100
5 VOIDRATIO
DEPTH (ft)

CONSOLIDATION TEST RESULTS
DESCRIPTION :
:

STRESS, ksf

INITIAL
FINAL
Drawing No.
17 PERCENTSATURATION
ST
R
A
I
N
,

%
MOISTURECONTENT (%)DRY DENSITY(pcf)
Project Name
Central Coast Blue Advanced Water Treatment
972 Huber Street, Grover Beach, California
Converse Project No. 21-31-323-00 (01)
For: - Carollo

0.460
20 100

0.636
:5
100
BH-3
112
BORING NO.

Silty Sand (SM)
NOTE: SOLID CIRCLES INDICATE READINGS AFTER ADDITION OF WATER B-3
Project No.
21-31-323-01Converse Consultants
Project ID: 323.GPJ; Template: CONSOLIDATION

0 500
1,000
1,500
2,000
2,500
3,000
3,500
4,000
0 1,000 2,000 3,000 4,000
21-31-323-01
DESCRIPTION :

SURCHARGE PRESSURE, psf
:
:
5-6.5
DRY DENSITY (pcf)

DIRECT SHEAR TEST RESULTS
:96.0
COHESION (psf)
NOTE: Ultimate Strength.

DEPTH (ft)
MOISTURE CONTENT (%)
SH
E
A
R

S
T
R
E
N
G
T
H
,

p
s
f
FRICTION ANGLE (degrees)
:
:BORING NO.

B-4a
32:

BH-1
Clayey Sand (SC)
100

7.0 Central Coast Blue Advanced Water Treatment
972 Huber Street, Grover Beach, California
Converse Project No. 21-31-323-00 (01)
For: - Carollo
Drawing No.Project No.Project Name
Project ID: 323.GPJ; Template: DIRECT SHEAR
Converse Consultants

0 500
1,000
1,500
2,000
2,500
3,000
3,500
4,000
0 1,000 2,000 3,000 4,000
21-31-323-01
DESCRIPTION :

SURCHARGE PRESSURE, psf
:
:
25-26.5
DRY DENSITY (pcf)

DIRECT SHEAR TEST RESULTS
:106.0
COHESION (psf)
NOTE: Ultimate Strength.

DEPTH (ft)
MOISTURE CONTENT (%)
SH
E
A
R

S
T
R
E
N
G
T
H
,

p
s
f
FRICTION ANGLE (degrees)
:
:BORING NO.

B-4b
30:

BH-2
Silty Sand (SM)
50 22.0
Central Coast Blue Advanced Water Treatment
972 Huber Street, Grover Beach, California
Converse Project No. 21-31-323-00 (01)
For: - Carollo
Drawing No.Project No.Project Name
Project ID: 323.GPJ; Template: DIRECT SHEAR
Converse Consultants

SAND EQUIVALENT TEST
ASTM D 2419
Client Name: Converse Consultants AP Job No.: 22-0552
Project Name: Central Coast Blue Advanced Water Test Date: 05/26/22 Project No.:

Boring Sample Depth Soil Clay Sand Corrected Sand Sand
No. Type Description Reading Reading Reading Equivalent B-4 SPT 10" Silty Sand 11.7 12.7 2.7 24

21-31-323-01

CORROSION TEST RESULTS
Client Name: Converse Consultants AP Job No.: 22-0552
Project Name: Central Coast Blue Advanced Water Date:05/26/22 Project No.: 21-31-323-01
Boring Sample Depth Soil pH Sulfate Content Chloride Content No. Type (feet) Description (ppm)(ppm)
BH-3 SPT - Silty Sand 8.1 26 21

NOTES: Resistivity Test and pH: California Test Method 643 Sulfate Content : California Test Method 417 Chloride Content : California Test Method 422
ND = Not Detectable
NA = Not Sufficient Sample
NR = Not Requested
Minimum
(ohm-cm)
12,225
Resistivity

Appendix C

Liquefaction and Settlement Analysis

Geotechnical Investigation Report
Central Coast Blue Advanced Water Treatment Project
Grover Beach, California
June 14, 2022
Page C-1

Converse Consultants
K:\31-Geotech\2021\21-31-323, Carollo, Central Coast Blue Advanced Water Treatment\Report\21-31-323 GIR (01) Grover Beach 6-15-22 FINAL.docx

APPENDIX C: LIQUEFACTION AND SETTLEMENT ANALYSIS

The subsurface data obtained from the borings BH-2 was used to evaluate the liquefaction potential and associated dry seismic settlement when subjected to ground shaking during earthquakes.

A simplified liquefaction hazard analysis was performed using the program SPTLIQ (InfraGEO Software, 2021) using the liquefaction triggering analysis method by Boulanger and Idriss (2014). A modal earthquake magnitude of M 6.7 was selected based on the results of seismic deaggregation analysis using the USGS interactive online tool ( https://earthquake.usgs.gov/hazards/interactive/) .

A peak ground acceleration (PGAGM) of 0.515 g for the MCE design event, where g is the acceleration due to gravity, was selected for this analysis. The result of our analysis is presented on Plate No. C-1 and summarized in the following table.

Table No. C-1, Estimated Dynamic Settlements
Location Groundwater
Conditions
Groundwater Depth
(feet bgs)
Dry Seismic
Settlement (inches)
Liquefaction Induced
Settlement (inches)
BH-2 Historical ~ 5 0 0.6

Based on our liquefaction analyses, liquefaction settlement is 0.6 inches for the subject site. Dry sand settlement is negligible. The differential settlement resulting from dynamic loads is anticipated to be 0.3 inch or less over a horizontal distance of 30 feet.

If the proposed development will be constructed 20 feet below ground level, then liquefaction settlement can be negligible.

Severity of Liquefaction:

Total Thickness of Liquefiable Soils: 10.00 feet (cumulative total thickness in the upper 65 feet) Liquefaction Potential Index (LPI): 6.51 *** (High risk, with moderate liquefaction effects) Seismic Ground Settlements: Upper 30 feet Upper 50 feet Upper 65 feet Seismic Compression Settlement: 0.00 inches 0.00 inches 0.00 inches

6.70 Liquefaction-Induced Settlement:0.59 inches 0.59 inches 0.59 inches

0.52 Total Seismic Settlement:0.59 inches 0.59 inches 0.59 inches

1.30 Seismic Lateral Displacements: Upper 30 feet Upper 50 feet Upper 65 feet Cyclic Lateral Displacement:0.52 inches 0.58 inches 0.58 inches (During Ground Shaking) BH-2 Lateral Spreading Displacement:0.00 inches 0.00 inches 0.00 inches (After Ground Shaking)

20.00 20.00

11.00 feet

5.00 feet

8.00 inches
140.00 pounds

30.00 inches

80.00 %

5.00 feet
TSC1

0.00 %
N/A H =
120.00 pcf (assumed)
Depth to
Top of
Soil Layer
Depth to
Bottom of
Soil Layer
Material Type
USCS
Group Symbol
(ASTM D2487)
Liquefaction
Susceptibility
Screening
++
Susceptible
Soil? (Y/N)
Total Soil
Unit
Weight
t
Type of
Soil
Sampler
Field
SPT Blow
Count
Nfield
Fines
Content
FC
Total
Vert.

Stress
(Design)
vo
Effective
Vert.

Stress
(Design)
'vo
SPT
Corr.
for
Vert.

Stress
CN
SPT
Corr.
for
Hammer
Energy
CE
SPT
Corr.
for
Borehole
Size
CB
SPT
Corr.
for
Rod
Length
CR
SPT
Corr.
for
Sampling
Method
CS
Corrected
SPT Blow
Count
N60
Normalized
SPT Blow
Count
(N1)60
Fines
Corrected
SPT Blow
Count
(N1)60cs
Shear
Stress
Reduction
Coefficient
rd
Correction
for High
Overburden
Stress
K
Cyclic
Stress
Ratio
CSR
Cyclic
Resistance
Ratio
CRR
Factor of
Safety
*
FSliq
Liquefaction
Analysis
Results
(feet) (feet)(pcf)(blows/ft) (%)(psf) (psf)(psf) (%) (inches) (inches) (inches)

0.00 5.00 SM Y 105.00 MCal 50.00 40.00 262.50 262.50 1.516 1.333 1.150 0.750 0.650 37.4 56.7 62.3 0.999 1.100 0.338 Unsaturated Soil 0.59 0.58 0.00

5.00 10.00 SM Y 106.00 MCal 19.00 45.00 790.00 634.00 1.478 1.333 1.150 0.800 0.650 15.1 22.4 28.0 0.980 1.100 0.413 0.531 1.29 LIQUEFY 203.81 46.85 0.59 0.58 0.00

10.00 15.00 SM Y 130.00 MCal 19.00 40.00 1,380.00 912.00 1.229 1.333 1.150 0.850 0.650 16.1 19.8 25.4 0.957 1.062 0.490 0.386 0.79 LIQUEFY 202.76 100.00 0.49 0.42 0.00

15.00 20.00 SM Y 115.00 MCal 46.00 40.00 1,992.50 1,212.50 1.062 1.333 1.150 0.950 0.650 43.6 46.3 51.8 0.932 1.069 0.518 Dense Soil 0.00 0.19 0.00

20.00 25.00 SM Y 120.00 SPT1 23.00 35.00 2,580.00 1,488.00 1.024 1.333 1.150 0.950 1.000 33.5 34.3 39.8 0.905 1.018 0.530 Dense Soil 0.00 0.19 0.00

25.00 30.00 SM Y 120.00 MCal 31.00 30.00 3,180.00 1,776.00 0.973 1.333 1.150 0.950 0.650 29.4 28.6 33.9 0.875 0.986 0.530 Dense Soil 0.00 0.17 0.00

30.00 35.00 SM Y 120.00 SPT1 50.00 26.00 3,780.00 2,064.00 0.977 1.333 1.150 1.000 1.000 76.7 74.9 80.0 0.845 0.941 0.523 Dense Soil 0.00 0.06 0.00

35.00 40.00 SM Y 120.00 SPT1 39.00 27.00 4,380.00 2,352.00 0.937 1.333 1.150 1.000 1.000 59.8 56.0 61.3 0.814 0.907 0.512 Dense Soil 0.00 0.06 0.00

40.00 45.00 SM Y 120.00 SPT1 24.00 28.00 4,980.00 2,640.00 0.866 1.333 1.150 1.000 1.000 36.8 31.9 37.1 0.783 0.909 0.499 Dense Soil 0.00 0.06 0.00

45.00 50.00 SM Y 120.00 SPT1 50.00 28.00 5,580.00 2,928.00 0.935 1.333 1.150 1.000 1.000 76.7 71.7 77.0 0.753 0.850 0.485 Dense Soil 0.00 0.00 0.00 REFERENCES:

1. Boulanger, R.W. and Idriss, I.M. (2014), "CPT and SPT Based Liquefaction Triggering Procedures," University of California Davis, Center for Geotechnical Modeling Report No. UCD/CGM-14/01, 1-1

2. Bray, J.D., and Sancio, R.B. (2006). "Assessment of the liquefaction susceptibility of fine-grained soils," Journal of Geotechnical and Geoenvironmental Engineering, ASCE 132 (9), 1165-11

3. Cetin, K.O. and Seed, R.B., et al. (2004), "Standard penetration test-based probabilistic and deterministic assessment of seismic soil liquefaction potential," Journal of Geotechnical and Geoenvironmental Engineering, ASCE 130 (12), 1314-1

4. Idriss, I.M. and Boulanger, R.W. (2008), "Soil Liquefaction During Earthquakes", Earthquake Engineering Research Institute (EERI), Monograph MNO-1

5. Ishihara, K. and Yoshimine, M. (1992), "Evaluation of settlements in sand deposits following liquefaction during earthquakes," Soils and Foundations, Japanese Geotechnical Society, 32 (1), 173-1

6. Iwasaki, T., et al. (1978), "A practical method for assessing soil liquefaction potential based on case studies at various sites in Japan," Proceedings Of 3rd International Conference of Microzonation, San Francisco, 885

7. Olson, S.M. and Johnson, C.I. (2008), "Analyzing Liquefaction-Induced Lateral Spreads Using Strength Ratios," Journal of Geotechnical and Geoenvironmental Engineering, ASCE 134 (8), 1035-10

8. Pradel, D. (1998), "Procedure to Evaluate Earthquake-Induced Settlements in Dry Sandy Soils," Journal of Geotechnical Engineering, ASCE 124 (4), pp. 364-36

9. Seed, R.B. and Harder, L.F. (1990), "SPT-based analysis of cyclic pore pressure generation and undrained residual strength, Proceedings Of Seed Memorial Symposium, Vancouver, B.C., 351-3

10. Tokimatsu, K. and Seed, H.B. (1987), "Evaluation of settlements in sands due to earthquake shaking," Journal of Geotechnical Engineering, ASCE 113 (GT8), 861-87

11. Tokimatsu, K. and Asaka, Y. (1998), "Effects of liquefaction-induced ground displacementson pile performance in the 1995 Hyogoken-Nambu Earthquake," Soils and Foundations, Special Issue, Japan Geotechnical Society, 163-

12. Tonkin & Taylor (2013), "Liquefaction Vulnerability Study," Report prepared for the Earthquake Commission (EQC), February, T&T Report No. 520.20.020

13. Toprak, S. and Holzer, T.L. (2003), "Liquefaction Potential Index: Field Assessment," Journal of Geotechnical and Geoenviromental Engineering, ASCE 129 (4), 315-3

14. Youd, T.L, Idriss, I.M., et al. (2001), "Liquefaction resistance of soils: summary report from the 1996 NCEER and 1998 NCEER/NSF Workshops", Journal of Geotechnical and Geoenvironmental Engineering, ASCE 127 (10), 817-8

15. Zhang, G, Robertson, P.K. and Brachman, R.W.I. (2004), "Estimating liquefaction-induced lateral displacement using the standard penetration test or cone penetration test," Journal of Geotechnical and Geoenvironmental Engineering, ASCE 130 (8), 861-8 (Dry/Unsaturated Soils)
(Saturated Soils)Ishihara and Yoshimine (1992)

SIMPLIFIED LIQUEFACTION HAZARDS ASSESSMENT USING STANDARD PENETRATION TEST (SPT) DATA (Copyright © 2015, 2020, SPTLIQ, All Rights Reserved; By: InfraGEO Software) Water Treatment Project
P.Ariram
Sivathasan
Analyzed By
Reviewed By

SUMMARY OF RESULTS
Analysis Method

PROJECT INFORMATION
Project Name
Analysis Method
Tokimatsu and Asaka (1998)
Zhang et al. (2004)
Pradel (1998)
g
feet
21-31-323-01
Grover Beach
Average Total Unit Weight of New Fill

SEISMIC DESIGN PARAMETERS
Earthquake Moment Magnitude, Mw
Borehole Diameter
Hammer Weight
GWL Depth Measured During Test
GWL Depth Used in Design
Boring No.

Ground Surface Elevation
Factor of Safety Against Liquefaction, FS
Project No.

Project Location

BORING DATA AND SITE CONDITIONS
Peak Ground Acceleration, Amax
- Ground Slope, S
Proposed Grade Elevation
Hammer Distance to Ground Surface
Topographic Site Condition:
feet
(Level Ground with No Nearby Free Face)
Hammer Drop
Hammer Energy Efficiency Ratio, ER
+ This method of analysis is based on observed seismic performance of level ground sites using correlation with normalized and fines-corrected SPT blow count, (N1)60cs = f{(N1)60, FC} where (N1)60 = Nfield CN CE CB CR CS * FSliq = Factor of Safety against liquefaction = (CRR/CSR), where CRR = CRR7.5 MSF K K , MSF = Magnitude Scaling Factor, K = f[(N1)60, 'vo], K =1.0, (level ground), ++ Liquefaction susceptibility screening is performed to identify soil layers assessed to be non-liquefiable based on laboratory test results using the criteria proposed by Cetin and Seed (2003), Bray and Sancio (2006), or Idriss and Boulanger (2008).

NOTES AND REFERENCES
0 feet
** Residual strength values of liquefied soils are based on correlation with post-earthquake, normalized and fines-corrected SPT blow count derived by Idriss and Boulanger (2008).

CSR = Cyclic Stress Ratio = 0.65 Amax (vo/'vo) rd , and CRR7.5 = Cyclic Resistance Ratio is a function of (N1)60cs and corrected for an earthquake magnitude Mw of 7.5. *** Based on Iwasaki et al. (1978) and Toprak and Holzer (2003) INPUT SOIL PROFILE DATA Residual
Shear
Strength
**
Sr
LIQUEFACTION TRIGGERING ANALYSIS BASED ON R.W. BOULANGER AND I.M. IDRISS (2014) METHOD +Cumulative Cyclic
Lateral
Displacement
Cumulative
Lateral
Spreading
Displacement
Seismic
Porewater
Pressure
Ratio
ru
Cumulative
Seismic
Settlement
+ Reference: Boulanger, R.W. and Idriss, I.M. (2014), "CPT and SPT Based Liquefaction Triggering Procedures," University of California Davis, Center for Geotechnical Modeling Report No. UCD/CGM-14/01, 1-134. - Free Face (L/H) Ratio SPTLIQ(cc)SPTLIQ Output Sheet 1

BH-2

20.00 20.00

8.00 140.00
Hammer Drop 30.00
Hammer Energy Efficiency Ratio, ER 80.00

0.00 Hammer Distance to Ground Surface 5.00
N/A H = 0.00 feet
Earthquake Moment Magnitude, Mw 6.70
GWL Depth Measured During Test 11.00 feet Peak Ground Acceleration, Amax 0.52 g GWL Depth Used in Design 5.00 feet Factor of Safety Against Liquefaction, FS 1.30 Boulanger-Idriss (2014)Above GWL:

Below GWL:

SEISMIC DESIGN PARAMETERS

GROUNDWATER DATA
Reviewed By

BORING DATA
%
Ground Surface Elevation
Proposed Grade Elevation
Water Treatment Project

TOPOGRAPHIC CONDITIONS
Boring No.
21-31-323-01
Grover Beach
P.Ariram
Sivathasan Hammer Weight
%
Ground Slope, S
Free Face (L/H) Ratio
feet
inches
pounds
feet
feet
inches
Analysis Methods Used ==>>
Project Location
Analyzed By Borehole Diameter
Below GWL: Ishihara and Yoshimine (1992)Tokimatsu and Asaka (1998) Pradel (1998)
Lateral Spreading:Liquefaction Triggering:

SIMPLIFIED LIQUEFACTION HAZARDS ASSESSMENT USING STANDARD PENETRATION TEST (SPT) DATA (Copyright © 2015, 2020, SPTLIQ, All Rights Reserved; By: InfraGEO Software)

PROJECT INFORMATION
Project Name
Project No.

Pradel (1998)
Cyclic Lateral Displacements:Seismic Settlements:

Zhang et al. (2004)Above GWL:
0 5
10 15
20 25
30 35
40 45
50 55
60 65
70 75

0.00 0.25 0.50 0.75 1.00
CSR = Cyclic Stress Ratio;
CRR = Cyclic Resistance Ratio
CSR (Load)
CRR (Resistance)
0 5
10 15
20 25
30 35
40 45
50 55
60 65
70 75

0.00 0.50 1.00 1.50 2.00
Factor of Safety, FS
Required FS
Computed FS
GWL
0 5
10 15
20 25
30 35
40 45
50 55
60 65
70 75
0255075100125
So
i
l

D
e
p
t
h

D
u
r
i
n
g

T
e
s
t

(
f
e
e
t
)
SPT N-values and Fines Content
N60, (N1)60cs ; FC (%)
SPT N60
SPT (N1)60cs
FC (%)
0 5
10 15
20 25
30 35
40 45
50 55
60 65
70 75

0.00 0.20 0.40 0.60 0.80
Seismic Settlement (in.)
0 5
10 15
20 25
30 35
40 45
50 55
60 65
70 75

0.00 0.20 0.40 0.60 0.80
Cyclic Lateral Disp. (in.)
0 5
10 15
20 25
30 35
40 45
50 55
60 65
70 75

0.00 0.50 1.00
Lateral Spreading (in.)
SPTLIQ(cc)SPTLIQ Output Sheet 2

Appendix D

Percolation Testing

Geotechnical Investigation Report
Central Coast Blue Advanced Water Treatment Project
Grover Beach, California
June 14, 2022
Page D-1

Converse Consultants
K:\31-Geotech\2021\21-31-323, Carollo, Central Coast Blue Advanced Water Treatment\Report\21-31-323 GIR (01) Grover Beach 6-15-22 FINAL.docx

APPENDIX D: PERCOLATION TESTING

Percolation tests were performed utilizing four borings PT-1, PT-2, PT-3 and PT-4, on July 6, 2022. The borings were pre-soaked prior to performing four (4) falling-head percolation tests to determine infiltration rates of the fill and native soils encountered between different depths below the ground surface at the Borings in accordance with LA County Low Impact Development, Best Management Practices Guidelines. The test borings were prepared by placing a perforated 2-inch diameter PVC pipe surrounded by pea gravel after drilling and sampling. Water was filled to the ground surface to pre-soak prior to testing.

Water was added to the bore holes until the water level was as near the ground surface as could be achieved and allowed to pre-soak for at least 1. After pre-soak water was added, until the water levels were as near required testing depth as could be achieved.

The water levels were measured to the nearest 1/20-foot and recorded every 10 minutes for borings. The results of the percolation tests are tabulated below.

Table No. D-1, Percolation Test Results
Boring No.

Depth of
Boring*
(feet)
Predominant Soil Types
(USCS)
Average
Percolation Rate
(inches/hour)
Design
Percolation Rate
(inches/hour)
PT-1 0-4 Silty Sand (SM) 8.53 8.44
PT-2 0-6 Silty Sand (SM) 13.61 13.27
PT-3 0-4 Silty Sand (SM) 10.78 10.78
PT-4 0-6 Silty Sand (SM) 11.36 11.20
*Approximate Depth

In accordance with County of Los Angeles requirements, the minimum percolation rate for design of infiltration system for storm water management is 0.30 inch per hour.

Percolation rates of borings PT-1, PT-2, PT-3 and PT-4 meet the minimum percolation rate. The project Civil Engineer should review the raw data of percolation test presented herein to determine specific soil layers and percolation rates for design of the proposed infiltration system. Such systems should be constructed a minimum distance of 10 feet laterally from any existing or future planned building or subsurface structure as not to disturb or undermine foundations. The proposed infiltration system should be constructed 10 feet above seasonal ground water table. The percolation rates were determined in general accordance with Los Angeles County guidelines. The detailed percolation test results are shown on the following data sheet.

Percolation Testing
Job Name:Central Coast Blue Advanced Water Treatment Project Test Boring No.PT-1 Job No.:21-323-02 Depth of Boring (db):4.0 feet
Location:972 Huber Street, Grover Beach, California Diameter of Boring (D):0.33 feet Test Date:Test Performer:Daniel Arteaga
Ground water was not encountered. Percolation test was performed between ___0.0____ feet and _____4.0____ feet below ground level.

Initial Time Final Time Time Interval Initial depth to
water
Final depth to
water
Initial Height
of water
column
Final Height of
water column Drop in Height
Average
height of water
column
Pre-adjusted
Percolation
Rate
Reduction
Factor
Adjusted
Percolation
Rate
T i T f DT d1 d2 di df Dd = di - df Lave k i =Dd / DT R f k = k i / R f (min)(min)(hr)(feet)(feet)(feet)(feet)(feet)(feet)(inch/hr)(inch/hr) Presoak 7/6/2022 1
Percolation Test

0.00 10.00 0.17 0.00 2.25 4.00 1.75 2.25 2.88 162.00 18.4 8.79

10.00 20.00 0.17 0.00 2.25 4.00 1.75 2.25 2.88 162.00 18.4 8.79

20.00 30.00 0.17 0.00 2.15 4.00 1.85 2.15 2.93 154.80 18.7 8.27

30.00 40.00 0.17 0.00 2.15 4.00 1.85 2.15 2.93 154.80 18.7 8.27 Note:Reduction Factor, R f = (2*di - Dd)/D +1
Lowest Perlcolaton Rate =8.27 inch/hr
Average Percolation Rate =8.53 inch/hr
Design Percolation Rate =8.44 inch/hr
Reference:Los Angeles County (2014). Adminstrative Manual - Guidelines for Design, Investigation, and Reporting Low Impact Development Storm Water Infiltration , 12/31/14.

Percolation Rate CalculationsWater Level Measurement
July 6, 2022
Time of Testing Water Level Calculations
D
db
dG

Percolation Testing
Job Name:Central Coast Blue Advanced Water Treatment Project Test Boring No.PT-2 Job No.:21-323-02 Depth of Boring (db):6.0 feet
Location:972 Huber Street, Grover Beach, California Diameter of Boring (D):0.33 feet Test Date:Test Performer:Daniel Arteaga
Ground water was not encountered. Percolation test was performed between ___0.0____ feet and _____6.0____ feet below ground level.

Initial Time Final Time Time Interval Initial depth to
water
Final depth to
water
Initial Height
of water
column
Final Height of
water column Drop in Height
Average
height of water
column
Pre-adjusted
Percolation
Rate
Reduction
Factor
Adjusted
Percolation
Rate
T i T f DT d1 d2 di df Dd = di - df Lave k i =Dd / DT R f k = k i / R f (min)(min)(hr)(feet)(feet)(feet)(feet)(feet)(feet)(inch/hr)(inch/hr) Presoak 7/6/2022 1
Percolation Test

0.00 10.00 0.17 0.00 4.70 6.00 1.30 4.70 3.65 338.40 23.1 14.64

10.00 20.00 0.17 0.00 4.60 6.00 1.40 4.60 3.70 331.20 23.4 14.14

20.00 30.00 0.17 0.00 4.35 6.00 1.65 4.35 3.83 313.20 24.2 12.95

30.00 40.00 0.17 0.00 4.30 6.00 1.70 4.30 3.85 309.60 24.3 12.72 Note:Reduction Factor, R f = (2*di - Dd)/D +1
Lowest Perlcolaton Rate =12.72 inch/hr
Average Percolation Rate =13.61 inch/hr
Design Percolation Rate =13.27 inch/hr
Reference:Los Angeles County (2014). Adminstrative Manual - Guidelines for Design, Investigation, and Reporting Low Impact Development Storm Water Infiltration , 12/31/14.

Percolation Rate CalculationsWater Level Measurement
July 6, 2022
Time of Testing Water Level Calculations
D
db
dG

Percolation Testing
Job Name:Central Coast Blue Advanced Water Treatment Project Test Boring No.PT-3 Job No.:21-323-02 Depth of Boring (db):4.0 feet
Location:972 Huber Street, Grover Beach, California Diameter of Boring (D):0.33 feet Test Date:Test Performer:Daniel Arteaga
Ground water was not encountered. Percolation test was performed between ___0.0____ feet and _____4.0____ feet below ground level.

Initial Time Final Time Time Interval Initial depth to
water
Final depth to
water
Initial Height
of water
column
Final Height of
water column Drop in Height
Average
height of water
column
Pre-adjusted
Percolation
Rate
Reduction
Factor
Adjusted
Percolation
Rate
T i T f DT d1 d2 di df Dd = di - df Lave k i =Dd / DT R f k = k i / R f (min)(min)(hr)(feet)(feet)(feet)(feet)(feet)(feet)(inch/hr)(inch/hr) Presoak 7/6/2022 1
Percolation Test

0.00 10.00 0.17 0.00 2.60 4.00 1.40 2.60 2.70 187.20 17.4 10.78

10.00 20.00 0.17 0.00 2.60 4.00 1.40 2.60 2.70 187.20 17.4 10.78

20.00 30.00 0.17 0.00 2.60 4.00 1.40 2.60 2.70 187.20 17.4 10.78

30.00 40.00 0.17 0.00 2.60 4.00 1.40 2.60 2.70 187.20 17.4 10.78 Note:Reduction Factor, R f = (2*di - Dd)/D +1
Lowest Perlcolaton Rate =10.78 inch/hr
Average Percolation Rate =10.78 inch/hr
Design Percolation Rate =10.78 inch/hr
Reference:Los Angeles County (2014). Adminstrative Manual - Guidelines for Design, Investigation, and Reporting Low Impact Development Storm Water Infiltration , 12/31/14.

Percolation Rate CalculationsWater Level Measurement
July 6, 2022
Time of Testing Water Level Calculations
D
db
dG

Percolation Testing
Job Name:Central Coast Blue Advanced Water Treatment Project Test Boring No.PT-4 Job No.:21-323-02 Depth of Boring (db):6.0 feet
Location:972 Huber Street, Grover Beach, California Diameter of Boring (D):0.33 feet Test Date:Test Performer:Daniel Arteaga
Ground water was not encountered. Percolation test was performed between ___0.0____ feet and _____6.0____ feet below ground level.

Initial Time Final Time Time Interval Initial depth to
water
Final depth to
water
Initial Height
of water
column
Final Height of
water column Drop in Height
Average
height of water
column
Pre-adjusted
Percolation
Rate
Reduction
Factor
Adjusted
Percolation
Rate
T i T f DT d1 d2 di df Dd = di - df Lave k i =Dd / DT R f k = k i / R f (min)(min)(hr)(feet)(feet)(feet)(feet)(feet)(feet)(inch/hr)(inch/hr) Presoak 7/6/2022 1
Percolation Test

0.00 10.00 0.17 0.00 4.10 6.00 1.90 4.10 3.95 295.20 24.9 11.84

10.00 20.00 0.17 0.00 4.00 6.00 2.00 4.00 4.00 288.00 25.2 11.41

20.00 30.00 0.17 0.00 3.95 6.00 2.05 3.95 4.03 284.40 25.4 11.20

30.00 40.00 0.17 0.00 3.90 6.00 2.10 3.90 4.05 280.80 25.5 10.99 Note:Reduction Factor, R f = (2*di - Dd)/D +1
Lowest Perlcolaton Rate =10.99 inch/hr
Average Percolation Rate =11.36 inch/hr
Design Percolation Rate =11.20 inch/hr
Reference:Los Angeles County (2014). Adminstrative Manual - Guidelines for Design, Investigation, and Reporting Low Impact Development Storm Water Infiltration , 12/31/14.

Percolation Rate CalculationsWater Level Measurement
July 6, 2022
Time of Testing Water Level Calculations
D
db
dG

DRAFT GEOTECHNICAL REPORT
Central Coast Blue – Conveyance Pipeline
Various Locations
Grover Beach and Oceano, California
Yeh Project No.: 221-539
July 17, 2023

Prepared for:

Water Systems Consulting
805 Aerovista Lane, Suite 201
San Luis Obispo, California 93401
Attn: Justin Pickard, PE

Prepared by:

Yeh and Associates, Inc.
391 Front Street, Suite D
Grover Beach, California 93433
Phone: 805-481-9590

391 Front Street, Suite D
Grover Beach, CA 93433
(805) 481-9590
www.yeh-eng.com
Colorado California
Denver | Colorado Springs | Durango | Glenwood Springs | Grand Junction | Greeley Grover Beach | Ventura July 17, 2023 Project No. 221-539
Water Systems Consulting
805 Aerovista Lane, Suite 201
San Luis Obispo, California 93401
Attn: Mr. Justin Pickard, PE
Subject: DRAFT Geotechnical Report, Central Coast Blue – Conveyance Pipeline, Various Locations, Grover Beach and Oceano, California
Dear Mr. Pickard:

Yeh and Associates, Inc. is pleased to submit this report to provide geotechnical services for the design of the conveyance pipeline system for the Central Coast Blue project in Grover Beach, California. This report was prepared in accordance with our agreement for professional services dated July 26, 2022. Graphics showing the locations of the field explorations, an interpreted subsurface profile for key project components, and recommendations for the design of the conveyance pipeline, earthwork, and pavement rehabilitation are included with this report.

We appreciate the opportunity to be of service. Please contact Judd King at 805-481-9590 x285 or [email protected] if you have questions or require additional information.

Sincerely,
YEH AND ASSOCIATES, INC.

Reed J. Hooke, EIT Jamie L. Ross, PE
Senior Staff Engineer Project Engineer
Reviewed by:

Judd J. King, PE, GE
Senior Geotechnical Engineer

DRAFT Geotechnical Report Project No. 221-539
Central Coast Blue – Conveyance Pipeline July 17, 2023
i
Table of Contents

1. PURPOSE AND SCOPE OF STUDY .............................................................................................. 1

2. PROJECT UNDERSTANDING ...................................................................................................... 1

2.1 PROPOSED PROJECT ....................................................................................................................... 1

2.2 EXISTING SITE DESCRIPTION ............................................................................................................. 2

2.3 HISTORICAL LIQUEFACTION-RELATED DEFORMATION ............................................................................ 3

3. SUBSURFACE EXPLORATION .................................................................................................... 3

3.1 EXPLORATORY DRILLING .................................................................................................................. 3

3.2 LABORATORY TESTING .................................................................................................................... 4

3.3 PREVIOUS STUDIES ......................................................................................................................... 4

4. SITE CONDITIONS .................................................................................................................... 5

4.1 GEOLOGIC SETTING ........................................................................................................................ 5

4.2 SUBSURFACE CONDITIONS ............................................................................................................... 6

4.3 GROUNDWATER ............................................................................................................................ 8

5. CONCLUSIONS AND RECOMMENDATIONS ............................................................................... 8

5.1 EARTHWORK – GENERAL ................................................................................................................. 8

5.1.1 SUGGESTED MATERIAL SPECIFICATIONS .......................................................................................... 8

5.1.2 CLEARING AND GRUBBING ......................................................................................................... 10

5.1.3 COMPACTION AND GRADING ...................................................................................................... 10

5.1.4 FILL PLACEMENT ...................................................................................................................... 10

5.1.5 REUSE OF EXCAVATED ONSITE MATERIAL ..................................................................................... 11

5.2 LIQUEFACTION ............................................................................................................................. 11

5.3 CORROSION CONSIDERATIONS ........................................................................................................ 12

5.4 PIPELINE DESIGN.......................................................................................................................... 12

5.4.1 FOUNDATION SUPPORT ............................................................................................................. 13

5.4.2 PIPE BEDDING ......................................................................................................................... 14

5.4.3 PIPE ZONE MATERIAL ............................................................................................................... 14

5.4.4 TRENCH BACKFILL .................................................................................................................... 15

5.4.5 TRENCH PATCH ........................................................................................................................ 15

5.4.6 PIPE LOADS ............................................................................................................................. 15

5.5 TRENCHLESS INSTALLATION ............................................................................................................ 15

5.5.1 SUBSURFACE CONDITIONS AND CONSIDERATIONS ........................................................................... 16

5.5.2 JACKING RESISTANCE ................................................................................................................ 17

DRAFT Geotechnical Report Project No. 221-539
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ii

5.5.3 MONITORING .......................................................................................................................... 17

5.5.4 CONTACT GROUTING ................................................................................................................ 18

6. CONSTRUCTION CONSIDERATIONS ........................................................................................ 18

6.1 EXCAVATIONS .............................................................................................................................. 18

6.2 DEWATERING .............................................................................................................................. 19

6.3 ADJACENT FACILITIES .................................................................................................................... 20

6.4 EXCAVATION STABILITY ................................................................................................................. 21

6.5 SUBGRADE EVALUATION ................................................................................................................ 21

6.6 GRADING OBSERVATION................................................................................................................ 21

7. LIMITATIONS ......................................................................................................................... 21

8. REFERENCES .......................................................................................................................... 22

List of Figures
FIGURE 1: VICINITY MAP .............................................................................................................................................. 1 FIGURE 2: DAMAGE TO HOUSE IN OCEANO, CALIFORNIA FROM LATERAL SPREADING DURING 2003 SAN SIMEON EARTHQUAKE (USGS 2004A) .................................................................................................................................................. 2 FIGURE 3: GEOLOGIC MAP (HOLLAND 2013) .................................................................................................................. 5 FIGURE 4: TRENCH DETAIL .......................................................................................................................................... 13

List of Tables
TABLE 1: GEOTECHNICAL PROPERTIES ............................................................................................................................. 7 TABLE 2: GROUNDWATER DATA ..................................................................................................................................... 8 TABLE 3: COMPACTION REQUIREMENTS ........................................................................................................................ 10 TABLE 4: SUMMARY OF ANTICIPATED EXCAVATION CONDITIONS ....................................................................................... 18 List of Plates
Plate 1a – Northern Field Exploration Plan ............................................................................................................. 1 Plate 1b – Southern Field Exploration Plan ............................................................................................................. 2 Plate 1c – Cross Section A-A’ Map .......................................................................................................................... 3 Plate 2 – Subsurface Profile A-A’: Trenchless Crossing ........................................................................................... 4

List of Appendices
Appendix A – Boring Logs
Boring Log Legend ................................................................................................................................. A-1

DRAFT Geotechnical Report Project No. 221-539
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iii
Boring Logs 23B-01 to 14………………………………………………………………………………………………………A-2 to A-16 Appendix B – Results of Laboratory Testing
Summary of Laboratory Test Results .......................................................................................... ....B-1 to 2 Sieve....................................................................................................................................................... B-3 Soluble Sulfates and Soluble Chlorides.................................................................................................. B-4 Modified Proctor.................................................................................................................................... B-5 Direct Shear....................... ............................................................................................................. B-6 to 8 Hydraulic Conductivity.................................................................................................................. B-9 to 12 Appendix C – Groundwater Monitoring Data
Borings 23B-09 and 23B-10 (April to July 2023) .......................................................................... C-1 to C-2 Appendix D – Previous Studies
Cooper, Clark, & Associates (1979) Borings .......................................................................................... D-1 United States Geological Survey (2004a) San Simeon Earthquake Cross Sections and CPTs ...... D-2 to 27 Yeh and Associates (2019) SSLO CSD Redundancy Project Borings and CPTs ............................ D-28 to 37 Yeh and Associates (2020) Grover Beach CDBG 2020 Waterline Borings ........................................... D-38

DRAFT Geotechnical Report Project No. 221-539
Central Coast Blue – Conveyance Pipeline July 17, 2023
1 1. PURPOSE AND SCOPE OF
STUDY
Yeh and Associates was
retained by Water Systems
Consultants (WSC) to provide
geotechnical
recommendations for the
design of the new conveyance
pipeline system for the Central
Coast Blue Project in Grover
Beach and Oceano, California.

The approximate location and
extents of the proposed
improvements are shown on
Figure 1.

The geotechnical evaluation
consisted of a program of
project coordination, field
exploration, laboratory testing,
and engineering analyses to
develop the recommendations
in this report. This report discusses the subsurface conditions encountered, provides recommendations for design and construction of the conveyance pipeline, and presents general grading and seismic considerations relevant to the project.

2. PROJECT UNDERSTANDING
The purpose of this project is the design of a network of conveyance pipelines through Grover Beach and Oceano, California to deliver secondary effluent from the Pismo Beach Outfall line to an Advanced Water Treatment (AWT) plant planned on Barca Street in Grover Beach, California. Discharge pipelines will also be designed to convey brine from the AWT facility back to the Pismo Beach Outfall for disposal.

2.1 PROPOSED PROJECT
Plates 1a and 1b – the Field Exploration Maps present a plan of the project area and proposed improvements. The project includes the design of approximately 2 miles of pipeline to intercept Figure 1: Vicinity Map

DRAFT Geotechnical Report Project No. 221-539
Central Coast Blue – Conveyance Pipeline July 17, 2023
2 the Pismo Beach Outfall line on Highway 1 to convey secondary effluent to the proposed AWT plant on Barca Street. Once the water is treated, it will be injected back into the ground at designated injection sites in the area. This injected water will be used to supplement the region’s groundwater aquifers and reduce the impact of seawater intrusion into the existing production wells for the local Five Cities area (Pismo Beach, Grover Beach, Oceano, Arroyo Grande, and Shell Beach). Discharge brine from the AWT will be sent back to the Pismo Beach Outfall for eventual disposal into the Pacific Ocean. The pipeline will generally follow existing streets in Grover Beach, Oceano, and along Highway 1.

New pipeline materials are anticipated to be Fuseable PVC or HDPE pipe. Most of the new pipeline will be installed using conventional open trench methods with depths up to 5 feet below the existing ground surface. An approximately 120-foot-long trenchless crossing is proposed the Union Pacific Railroad (UPRR) tracks near the proposed AWT plant. Two casings, one for the secondary effluent pipeline, the other for the brine discharge line will be designed for the crossing. The proposed crossing is anticipated to be up to 15 feet below the ground surface and installed using jack and bore methods.

2.2 EXISTING SITE DESCRIPTION
The conveyance pipeline will generally follow existing streets in Grover Beach, Oceano, and east of Highway 1. The Grover Beach Train Station is
located near the northern extents of the proposed
pipeline, and the South San Luis Obispo County
Sanitation District (SSLOCSD) Wastewater Treatment
Facility (WWTF) is located near the southern extents
of the project. The proposed pipeline will cross right- of-way for both the Union Pacific Railroad (UPRR)
and Highway 1 as well as cross the Oceano Airport
property. Land use in the project vicinity is primarily residential, commercial, and industrial. The ground
surface along the project is generally flat or gently
sloping with elevations between 9 and 40 feet (WSC
2023). Grades along the proposed pipeline alignment
vary from approximately 0 to 10 percent (CalTopo
2023). Existing utilities within the roadways consist
of gas, sewer, water, storm drains, and the existing Figure 2: Damage to House in Oceano, California from Lateral Spreading During
2003 San Simeon Earthquake (USGS 2004a)

DRAFT Geotechnical Report Project No. 221-539
Central Coast Blue – Conveyance Pipeline July 17, 2023
3 Pismo Beach Outfall line that the new pipeline will intercept.

2.3 HISTORICAL LIQUEFACTION-RELATED DEFORMATION
The Oceano area was impacted by the 2003 San Simeon Earthquake (USGS 2004a). Damage to houses, roadways, and underground utilities was recorded, associated with lateral spreading in the vicinity (see Figure 2). Sand boils were also observed at various locations near Oceano Lagoon and Arroyo Grande Creek. The approximate locations of the lateral spreading and sand boils are shown on Plate 1b. USGS (2004a) notes that non-engineered fill derived from nearby sand dunes was used in 1927 to infill marshland to convert them into developable land. A discussion of liquefaction potential is discussed in Section 5.3.

3. SUBSURFACE EXPLORATION

3.1 EXPLORATORY DRILLING
Yeh subcontracted 2R Drilling Inc. of Chino, California to perform the drilling for the project. 2R used a CME 75 truck-mounted drill rig equipped with 8-inch diameter hollow stem augers to advance fourteen borings to depths of up to approximately 31 feet below the existing road surface on April 4 to 6, 2023. Plates 1a and 1b show the approximate locations of the borings.

The station and elevation of the borings along the project were estimated from the preliminary plans provided by WSC (2023).

Yeh personnel measured existing pavement sections, logged the subsurface conditions encountered during the drilling, and collected soil samples for subsequent laboratory testing.

The sample intervals, a description of the subsurface conditions encountered, pocket penetrometer test results, blow counts (N-Values) recorded during drive sampling, and percent recovery are provided on the logs. The logs of the borings are presented in Appendix A.

Sampling within the borings was performed by driving either a modified California or standard penetration test (SPT) split spoon sampler at intervals of 2.5 to 5 feet. The SPT sampler has a 2- inch outside diameter, a 1-3/8-inch inside diameter and is equipped for but was used without liners. The modified California sampler has a 3-inch outside diameter, a 2-3/8-inch inside diameter and was used with 1-inch-high brass liners. Drive samples were collected using a 140- pound automatic trip hammer in accordance with ASTM D-1586 (the Standard Penetration Test) procedures. Bulk samples of the subgrade soil were collected from the augers at the depth intervals noted on the logs.

DRAFT Geotechnical Report Project No. 221-539
Central Coast Blue – Conveyance Pipeline July 17, 2023
4 Upon completion, the borings less than 25 feet were backfilled with a mixture of cement and native material from the auger cuttings, then topped with a concrete patch dyed black. Borings 23B-09 and 23B-10 were instrumented as temporary 2-inch diameter monitoring wells. Details of the monitoring well construction are shown on the logs in Appendix A.

3.2 LABORATORY TESTING
Laboratory testing was performed on selected samples recovered from the borings. Results are presented in Appendix B. Tests for moisture content, unit weight, gradation, compaction, and pH and resistivity were performed at the Yeh office and laboratory in Grover Beach, California.

Tests for direct shear and hydraulic conductivity were performed by the California Polytechnic State University Geo-E Laboratory in San Luis Obispo, California. Tests for soluble sulfates and soluble chlorides in the soil were performed by Cooper Testing Labs, Inc. in Palo Alto, California.

All testing was performed in accordance with applicable ASTM standards.

3.3 PREVIOUS STUDIES
Previous studies were performed for separate projects and studies near the project vicinity.

Data from these studies were used to supplement this report and are summarized below. Logs of pertinent borings and cone penetration tests from the previous studies are provided in Appendix D. Locations of the previous study explorations are presented on Plates 1a and 1b. • A geotechnical investigation was completed by Cooper, Clark, and Associates (CCA 1979) for the design of improvements for the South San Luis Obispo County Sanitation District Wastewater Treatment Facility. One boring (Boring 2) was located near the proposed pipeline alignment and was used to supplement this report. • An assessment report was prepared by the United States Geological Survey (USGS 2004a) following the 2003 San Simeon Earthquake. The report included lateral spread and sand boil locations, as well as a link to cone penetration test (CPT) data performed for the study (USGS 2004b). Seventeen CPTs (SOC001 through SOC005, SOC010 through SOC015, SOC017, SOC020, SOC021, SOC027, SOC028, and SOC041) were performed near the proposed pipeline alignment and was used to supplement this report. Four cross sections were compiled for this study that show subsurface conditions encountered as well as liquefaction and lateral spread potential. • A Geotechnical Report was prepared by Yeh and Associates (Yeh 2019) for the South San Luis Obispo County Sanitation District (SSLOCSD) Wastewater Treatment Facility (WWTF) Redundancy project. One boring (16E-03) and two CPTs (CPT-01 and CPT-06) were performed near the proposed pipeline alignment and was used to supplement this report. Liquefaction analyses for the WWTF site were also performed for this project. • A Geotechnical Report was prepared by Yeh and Associates (Yeh 2020) for a waterline project for the City of Grover Beach. One boring (19P-05) from this study was located near the proposed pipeline alignment and was used to supplement this report.

DRAFT Geotechnical Report Project No. 221-539
Central Coast Blue – Conveyance Pipeline July 17, 2023
5 4. SITE CONDITIONS

4.1 GEOLOGIC SETTING
The project site is within the Coast Ranges geologic and geomorphic province, which extends from the Transverse Ranges in southern California to the Klamath Mountains in northern California and into Oregon. The province is characterized by north-northwest trending mountain ranges (locally the Santa Lucia Mountains) composed of sedimentary, volcanic, and metamorphic rock formations. The rock units are predominately Jurassic and Cretaceous age with Tertiary to Quaternary age units commonly overlying the older rock along the flanks and foothills of those ranges. Recent sediments are found within intervening drainages and valleys, and coastal areas.

The surficial geology in the project area as mapped by Holland (2013) is shown on Figure 3.

Geology along the proposed pipeline alignment is mapped by Holland (2013) as Holocene age Alluvium Flood-Plain deposits (Qa) and Pleistocene Old Eolian Deposits (Qoe). Geologic Figure 3: Geologic Map (Holland 2013)

DRAFT Geotechnical Report Project No. 221-539
Central Coast Blue – Conveyance Pipeline July 17, 2023
6 structure within the project vicinity includes the Oceano Fault mapped by Holland (2013) and USGS (2023) approximately 0.3-mile southwest of the southern extents of the proposed pipeline alignment. Other Quaternary age faults mapped by USGS (2023) the project vicinity includes a segment of the San Luis Range Fault System, Wilmar Avenue Fault, and Pecho Fault mapped 0.2-mile northeast, 2.3 miles northeast, and 2.4 miles southwest from the limits of the proposed pipeline alignment.

4.2 SUBSURFACE CONDITIONS
The typical subsurface conditions encountered in the borings performed for the project and explorations from previous studies consisted of roadway materials underlain by artificial fill (Af), alluvial flood-plain deposits (Qa), and old eolian deposits (Qoe). The approximate locations of the borings are shown on Plate 1a through 1c and noted on the boring logs in Appendix A. A description of the soil units encountered is summarized below.

Roadway Materials. Boring 23B-01 through 23B-07, 23B-09, and 23B-11 through 23B-14 were drilled within existing roadways along the proposed pipeline alignment. Pavement sections encountered in these borings consisted of approximately 1 to 7 inches of asphalt concrete over 0 to 9 inches of aggregate base. Artificial fill (Af), alluvial flood-plain deposits (Qa) and old eolian deposits (Qoe) were encountered below the roadway materials.

Artificial Fill (Af). Artificial fill associated with the infill of marshland within the Oceano Lagoon (USGS 2004a) was encountered in borings 23B-011 and 23B-12. The fill was encountered below the roadway materials to a depth of 5 feet below the ground surface in boring 23B-011, and to the maximum depth explored of approximately 11.5 feet below the ground surface in 23B-12.

The artificial fill encountered in borings 23B-011 and 23B-12 consisted of very loose to medium dense poorly graded sand (SP) and silty sand (SM). The same fill is also shown interpreted in the USGS (2004a) CPTs along Coolidge Drive to depths of 2 to 6 feet below the ground surface, as shown on the USGS (2004a) cross section C-C’ in Appendix D. Artificial fill was also encountered in boring 16E-03 (Yeh 2019) within the SSLOCSD WWTF from the ground surface to a depth of approximately 5 feet below the ground surface. The fill at the SSLOCSD WWTF consisted of loose clayey sand (SC). The fill encountered in borings 23B-11 and 16E-03 (Yeh 2019) was underlain by alluvial flood-plain deposits (Qa).

Alluvial Flood-Plain Deposits (Qa). Alluvial flood-plain deposits were encountered below the road material in borings 23B-13 and 23B-14 along the southern portion of the proposed pipeline alignment to the maximum depths explored of 11.5 feet below the ground surface. The unit was also encountered in borings 23B-09 and 23B-10 at the proposed UPRR crossing

DRAFT Geotechnical Report Project No. 221-539
Central Coast Blue – Conveyance Pipeline July 17, 2023
7 location from the ground surface to approximately 20 to 27 feet below the ground surface.

Alluvial flood-plain deposits were also encountered below the artificial fill in borings 23B-11 along Coolidge Drive and 16E-03 (Yeh 2019) at the SSLOCSD WWTF to the maximum depths explored of 11.5 to 81.5 feet below the ground surface, and from the ground surface in Boring 2 (CCA 1979) at the SSLOCSD WWTF to the maximum depth explored of approximately 30 feet below the ground surface. The alluvial flood-plain deposits predominantly consisted of very loose to medium dense poorly graded sand with varying amounts of silt and clay (SP, SC, SM). A layer of peat was encountered in boring 23B-11 from approximately 5 to 10 feet below the ground surface, likely associated with the “1874 Marsh” shown on the USGS (2004a) cross section C-C’ near similar depths (see Appendix D). Old eolian deposits (Qoe) were encountered below the alluvial flood-plain deposits in borings 23B-09 and 23B-10.

Old Eolian Deposits (Qoe). Old Eolian Deposits were encountered in borings 23B-01 to 23B-08 below the road material or below the ground surface to the maximum depths explored of approximately 5.5 to 11.5 feet below the ground surface. The unit was also encountered below the alluvial flood-plain deposits in borings 23B-09 and 23B-10 to the maximum depths explored of approximately 30.8 to 31 feet below the ground surface. The unit predominantly consisted mostly of loose to very dense poorly graded sand with varying amounts of silt (SP, SP-SM, SM).

A summary of the geotechnical properties and laboratory test results is presented in Table 1.

Table 1: Geotechnical Properties 1
Geologic Unit Locations
Encountered
Dry Unit
Wt.
(pcf)
Moisture
Content
(%)
Particle Size
Analyses
(%G, %S, %F)
Other
Artificial Fill
(Af) 23B-11, 23B-12 -- --
0 G
78 S
22 F
pH = 6.25
ρ = 4,269 Ω-cm
SO42- = 223 mg/kg
CL- = 21 mg/kg
Alluvial Flood-
Plain Deposits
(Qa)
23B-09 through
23B-11, 23B-13,
23B-14
28 - 120 7 - 176
0 - 53 G
41 - 99 S
1 - 29 F
pH = 5.21 - 7.98
ρ = 206 - 2,797 Ω-cm
SO42- = 19 - 7,877 mg/kg
CL- = 7 - 171 mg/kg 𝜙𝜙’ = 21 - 35.5°
c’ = 0.24 - 0.74 ksf

1 Geotechnical properties are noted for dry unit weight (γd) in lbs/ft3 (pcf) and moisture content (WC) in percent; particle size as percent gravel (G), sand size (S) and fines content (F); electrical resistivity (ρ) in ohm-centimeters (Ω-cm), effective friction angle (𝜙𝜙′) and cohesion (c’) in kips per square foot measured from direct shear tests; resistance ‘R’ values; pocket penetrometer values; maximum dry unit weight (γd,max) in lbs/ft3 (pcf) and optimum moisture content (WCOPT) in percent from modified proctor tests; and hydraulic conductivity (kavg).

DRAFT Geotechnical Report Project No. 221-539
Central Coast Blue – Conveyance Pipeline July 17, 2023
8 Geologic Unit Locations
Encountered
Dry Unit
Wt.
(pcf)
Moisture
Content
(%)
Particle Size
Analyses
(%G, %S, %F)
Other
Old Eolian
Deposits (Qoe)
23B-01 to 23B-08,
23B-10 89 - 106 4 - 24
0 - 1 G
82 - 95 S
5 - 18 F
pH = 4.11 - 6.82
ρ = 1,619 - 15,679 Ω-cm
SO42- = 7 - 77 mg/kg
CL- = 3 - 20 mg/kg
γd,max = 108 pcf
WCOPT = 13%
kavg = 4.0 x 10-4 - 6.3 x 10-3

4.3 GROUNDWATER
Table 2 summarizes the approximate groundwater depths, elevations, and dates when encountered in the borings performed for this study as well as borings from previous studies.

Yeh installed a Solinst Level Logger groundwater level measuring devices in the monitoring wells in borings 23B-09 and 23B-10 to automatically record daily groundwater levels beginning April 2023. A plot of those data through July 6, 2023 is presented in Appendix C. Groundwater and soil moisture conditions will vary seasonally and with changes in storm runoff, irrigation, groundwater pumping, and stream flow.

Table 2: Groundwater Data
Boring No.

Ground
Surface
Elevation
(feet)
Groundwater
Depth Below
Ground Surface
(feet)
Groundwater
Elevation (feet) Date Measured Notes
23B-09 19.0

6.0 6.45

6.75 13.0

12.55 12.25
04/04/2023
05/31/2023
07/06/2023
Level Logger
installed
23B-10 20.6

8.5 8.5

8.75 12.1

12.1 11.85
04/06/2023
05/31/2023
07/06/2023
Level Logger
installed
23B-11 10.0 5.5 4.5 04/04/2023 --
23B-12 15.0 4.0 11.0 04/04/2023 --
23B-13 11.0 3.3 7.7 04/04/2023 --
23B-14 11.2 5.0 6.2 04/04/2023 --

5. CONCLUSIONS AND RECOMMENDATIONS

5.1 EARTHWORK – GENERAL

5.1.1 SUGGESTED MATERIAL SPECIFICATIONS
Standard Specifications refers to the 2022 edition of the Standard Specifications published by the California Department of Transportation (Caltrans 2018) and City Specifications refers to the

DRAFT Geotechnical Report Project No. 221-539
Central Coast Blue – Conveyance Pipeline July 17, 2023
9 City of Grover Beach Standard Specifications (GB 2006). The following specifications are suggested for materials referenced in various sections of this report.

Aggregate Base. Aggregate base shall consist of imported material conforming to Section 26-

1.02B of the Standard Specifications for Class 2 Aggregate Base.

Asphalt Concrete. Asphalt Concrete shall conform to Section 39-2, “Hot Mix Asphalt,” of the Standard Specifications. City Specifications indicate the base course shall utilize ¾-inch maximum aggregate and ½-inch maximum aggregate for the surface course. The complete surface shall be sealed with fog seal applied 0.1 gallons per square yard in accordance with Standard Specifications Section 37-1. Asphalt binder shall be grade PG 64-10.

Compacted Fill. Compacted general fill material shall consist of imported or on-site material free of organics, oversize rock (greater than 3 inches), trash, debris, corrosive, or other deleterious materials. Fill and borrow sources shall be reviewed by the Geotechnical Professional before being imported to the site. Fill materials shall comply with all specified material requirements for the designated location as placed at the site.

Geotextile for Separation (Filter Fabric). Geotextiles for separation shall conform to Section 96-

1.02B of the Standard Specifications.

Gravel Bedding. Gravel Bedding placed for trench foundation stabilization (if needed) shall consist of angular crush rock that is free of organics, corrosive material, clay, recycled or reclaimed materials. Or other deleterious substances conforming to Class 1 Permeable Material (Type A) per Section 68-2.02F(2) if the Standard Specifications or No. 57 stone (1 inch x No. 4) per ASTM C33. Gravel bedding shall be fulling encased in a Geotextile for Separation (Filter Fabric) when in contact with in-situ or subsequent pipe zone or trench backfill material.

Pipe Bedding/Pipe Zone Material. Pipe Zone Material and Pipe Bedding shall consist of imported or onsite material conforming to Section 6.17-H of the City Specifications.

Slurry Cement Backfill. Slurry cement backfill used for Pipe Zone Material should conform to Section 19-3.02G of the Standard Specifications. Aggregate shall be import material conforming to the gradation and quality requirements of the Standard Specifications.

Trench Backfill. Trench Backfill shall consist of imported or onsite material that is free of organics, debris, oversized material (greater than 3 inches), and other deleterious materials.

The asphalt debris encountered in potholes shall be removed from trench backfill material prior

DRAFT Geotechnical Report Project No. 221-539
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10 to being used. Trench Backfill material shall have at least 85 percent of the material passing the U.S. Standard No. 4 sieve, and/or comply with the applicable requirements for the area where Trench Backfill is being placed (such as the pavement structural section).

5.1.2 CLEARING AND GRUBBING
Clearing and grubbing should be performed to remove existing vegetation and objectionable material from improvement areas that will be graded, receive fill, or serve as borrow sources.

Grubbing should include removing stumps, roots, and buried vegetation. Care should be taken not to injure trees, plants, existing improvements, or existing outfalls outside of the clearing limits. Soil containing pavement, debris, organics, unsuitable, loose, or disturbed material should be removed prior to placing fill. Demolition areas should be cleared of old foundations, existing fill, pavement, abandoned utilities, and soil disturbed during clearing and grubbing.

Depressions left from the removal or demolition of materials should be replaced with compacted fill.

5.1.3 COMPACTION AND GRADING
Fill placement and grading operations should be performed according to the recommendations of this report. Table 3 provides a summary of the minimum levels of compaction recommended for areas where fill could be placed. Relative compaction should be assessed according to the latest approved edition of ASTM Standard Test Method D1557.

Table 3: Compaction Requirements
Location of Fill Placement
Recommended Minimum
Relative Compaction
General 90% U.O.N.2
Utility trench bedding and pipe zone fill 90%
Fill or backfill placed within 3 feet of pavement
areas 95%
Asphalt concrete, aggregate base, or subbase 95%

5.1.4 FILL PLACEMENT
Jetting or ponding should not be permitted for placement or compaction of fill materials. Fill materials should be moisture conditioned and spread in lifts that are suitable for compaction with the equipment being used. Control of compaction layer thickness will be necessary to achieve compaction throughout the material being placed. Fill should typically be spread in

2 U.O.N. – unless otherwise noted

DRAFT Geotechnical Report Project No. 221-539
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11 loose lifts of approximately 8 inches or less, and within 2 percent of the optimum moisture content, to achieve the recommended compaction.

The moisture content of the material should be such that the specified compaction can be achieved in a firm and stable condition. Each layer should be spread evenly, bladed, and mixed to provide relative uniformity of material within each layer, and be moisture conditioned by adding water or drying the material to provide a moisture content suitable for compaction. Soft or yielding materials should be removed and replaced with properly compacted fill material prior to placing the next layer of fill. Fill and backfill materials may need to be placed in thinner lifts to achieve the recommended compaction with the equipment being used.

Particles greater than half the compacted lift thickness can limit compactive effort. The fill should not contain rocks, gravel, or other solid particles larger than 3 inches in the greatest dimension. Deleterious materials, such as soft rock particles, concrete or pavement rubble, metal, glass, or sharp objects should not be placed within the fill material being placed.

Recycled or reused materials should only be used and placed within the fill when specifically permitted by the project specifications. Rocks should not be nested, and voids should be filled with compacted fill material.

5.1.5 REUSE OF EXCAVATED ONSITE MATERIAL
Select fill materials needed for open trench excavations for the sewer line include Pipe Bedding, Pipe Zone Material, and Trench Backfill. The pipeline construction will likely encounter alluvial flood-plain deposits and old eolian deposits. Based upon sand equivalent and particle size gradation results from current and previous studies, excavated material consisting of poorly graded sand (SP, SP-SM) and silty sand (SM) are considered suitable for reuse as Pipe Bedding, Pipe Zone Material provided material greater than 1 inch is removed. Excavated material can be reused as Trench Backfill provided cobbles and boulders greater than 3 inches are removed.

The contractor should segregate this material, remove any material greater than 1 inch and provide periodic quality control laboratory testing showing the material meets project specifications.

5.2 LIQUEFACTION
Liquefaction typically occurs in young, loose to medium dense granular sand or sensitive clay and silt below the groundwater table in response to earthquake ground motions. Sand boils, seismic settlement, fissures, slope instability, and lateral spreading can occur in response to liquefaction. The consequences and severity of liquefaction vary depending on the magnitude, duration, and location of the earthquake. Liquefaction could be manifested as additional

DRAFT Geotechnical Report Project No. 221-539
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12 buoyancy loads on pipelines, loss of thrust resistance along pipe or thrust blocks, lateral displacement due to shaking or lateral spreading, loss of bearing resistance, and settlement.

The Oceano area has prior history of liquefaction-related deformation and damage (see Section

2.3).

The soil encountered in the borings for the conveyance pipeline predominantly consisted of very loose to medium dense sand with varying amounts of silt, clay, and gravel (SP, SP-SM, SM, SC). The loose to medium dense sandy soil encountered below the groundwater table in the trenchless crossing and the portion of the pipeline within the Oceano area is considered potentially liquefiable. USGS (2004a) noted that “the surficial geology and shallow water table at Oceano suggests a significant liquefaction hazard is present,”. USGS (2004a) identified liquefiable layers predominantly within the upper 10 feet below the ground surface in the Oceano area, as shown on the cross sections in Appendix D. Yeh (2019) also performed analyses for liquefaction potential at the SSLOCSD WWTF and identified liquefiable layers predominantly within the upper 14 to 25 feet of the site (see the CPT plots in Appendix D).

Stabilization of pipelines to address liquefaction are typically considered cost prohibitive.

Management and soft fixes are a common way to address the potential for liquefaction to affect the pipeline. The design could address this by implementing inspection procedures following a seismic event and budgeting the replacement of sections that have settled or been damaged due to liquefaction.

5.3 CORROSION CONSIDERATIONS
Selected samples from the field exploration programs were tested for pH, resistivity, soluble sulfates, and soluble chlorides in accordance with the relevant ASTM test methods. Results are presented in Table 1 and Appendix B. Guidance from the AWWA (2014) External Corrosion Control manual was used evaluate the severity of corrosion potential of the encountered soil.

Measured resistivity values of 206 to 15, 679 Ohm-cm indicate bad to excellent soils (groups I to IV) based on AWWA (2014) Table 3-2 for steel and should be considered corrosive. Measured pH values (4.11-7.98) are considered acidic to neutral. The designer should refer to AWWA guidelines or appropriate design standards and consider installing sacrificial anodes on the pipeline or other corrosion protection measures depending on the chosen pipe material type and connectors.

5.4 PIPELINE DESIGN
Figure 4 is the recommended typical trench detail consistent with the City of Grover Beach (2006) Standards and Specifications showing the recommended cross-sectional limits of the

DRAFT Geotechnical Report Project No. 221-539
Central Coast Blue – Conveyance Pipeline July 17, 2023
13 bedding, initial backfill, and subsequent backfill material for trench backfill. Material recommendations for bedding, pipe zone, and trench backfill material are described in Section

5.1.1 of this report. The pavement area shown in Figure 4 is applicable to the majority of the project where the pipeline will be installed using open cut trench methods below the existing road.

5.4.1 FOUNDATION SUPPORT
Prior to placing pipe bedding material, the foundation support soil exposed at the trench subgrade should be reviewed by the geotechnical professional. The subgrade conditions encountered near the anticipated trench depths in the borings within the Grover Beach area predominantly consisted of loose to medium dense sand above the groundwater table.

Subgrade conditions encountered near the anticipated trench depths in the borings within the Oceano area predominantly consisted of very loose to medium dense sand below the groundwater table. Unless stable subgrade conditions can be obtained with dewatering or other means, stabilization of the subgrade should be provided prior to placing the pipe. It is anticipated that trench subgrade will need to be stabilized throughout the pipeline route in Oceano. Subgrade stabilization should consist of removing the trench subgrade to 12 inches below the bottom of trench elevation and replacing the material with Gravel Bedding wrapped in a Geotextile for Separation (Filter Fabric) conforming to the suggested material specifications of this report.

Figure 4: Trench Detail

DRAFT Geotechnical Report Project No. 221-539
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14 Trench stabilization may be omitted if the bottom of the trench is firm and stable. In such conditions, prior to placing Pipe Bedding, the trench bottom should be scarified to a depth of 9 inches, moisture conditioned, and compacted in place to at least 90 percent relative compaction.

5.4.2 PIPE BEDDING
Pipe Bedding is the initial backfill placed between the trench subgrade and the bottom of the pipe. At least 6 inches of Pipe Bedding (or more if specified by engineer) should be placed on trench subgrade that is firm and dry, unless stabilization of the trench foundation is needed as discussed in Section 5.4.1. The pipe should be placed on the bedding such that the middle third of the pipe (D0/3 on Figure 4) is in contact with the bedding prior to placing initial backfill within the pipe zone. The bedding may be loosened along the invert of the pipe if necessary to help form the cradle. Pipe Bedding should be compacted to at least 90 percent relative compaction.

5.4.3 PIPE ZONE MATERIAL
Pipe Zone Material is material placed in the pipe zone from the top of the bedding material to at least 6 inches above the crown of the pipe. The Pipe Zone Material should be compacted to at least 90 percent relative compaction prior to placing subsequent trench backfill. Compaction within the pipe zone should be performed such that the pipe is fully supported during compaction and that excessive deformation or damage to the pipe does not occur and the pipe is not moved off its alignment. Pipe Zone Material should be placed simultaneously on either side of the pipe to help support the pipe during placement and compaction. Pipe Zone Material should not be placed above the springline until the pipe zone material below the springline has been placed and compacted properly to support the haunches.

Slurry Cement Backfill can be used for initial backfill in lieu of granular Pipe Zone Material when approved or recommended by the engineer and permitted by the pipe manufacturer. The Slurry Cement Backfill will likely not provide additional support or limit deflection of the pipe, unless the slurry is allowed to cure prior to placing subsequent Trench Backfill. The Slurry Cement Backfill should be placed over the crown of the pipe to allow for the slurry to flow into the trench on either side of the pipe simultaneously. The slurry should be vibrated during placement to help consolidate the material and assist in filling below the haunches of the pipe.

The pipe should be ballasted and secured to reduce the potential for the pipe to be displaced or float during placement. Slurry should not be placed above the springline of the pipe until the slurry below springline has adequately set or is specifically permitted by the engineer and pipe manufacturer. Subsequent Pipe Zone Material and Trench Backfill can be placed once the

DRAFT Geotechnical Report Project No. 221-539
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15 cement slurry has set such that foot traffic does not leave an imprint in the slurry of more than ¼-inch. Longer curing times, (perhaps 7 days or more) and/or special mix designs to reduce cure times, would be needed to provide springline support that is superior to soil backfill.

5.4.4 TRENCH BACKFILL
Trench Backfill is material placed in the trench from the top of the pipe zone to finished grade and includes the pavement structural section, where applicable. Subsequent backfill should consist of Slurry Cement Backfill or Trench Backfill material conforming to the recommendations described in Section 5.1.1 of this report. Trench Backfill placed within the upper 3 feet of the trench in pavement areas should be compacted to at least 95 percent relative compaction. In non-pavement areas, the upper 2 feet of the backfill should consist of onsite native soil or appropriate landscape soil to help reduce the potential for surface water to infiltrate the trench.

5.4.5 TRENCH PATCH
The existing pavement should be sawcut 6 inches beyond the edge of the trench. The width of the trench should comply with the minimum dimensions shown in Figure 4 and provided in the City of Grover Beach (2006) Standards and Specifications for segments of the pipeline within the Grover Beach city limits. Any broken or loosened asphalt that results from the cutting operation or instability of sidewalls during excavation should also be removed to a neat saw-cut edge. The trench patch should as a minimum match the thickness of the existing asphalt concrete plus an additional 1-inch. The pavement thickness encountered at the boring locations are presented in Section 4.2 of this report and listed on the logs in Appendix A. Class 2 Aggregate Base provided below the asphalt layer should have a thickness that will match the bottom of the existing structural section or a minimum of 6 inches, whichever is thicker.

5.4.6 PIPE LOADS
Pipelines should be designed to resist vertical loads resulting from the backfill. The load on the pipe can be estimated as the prism load. The prism load is the total weight of the soil acting above the pipe and applied over a width equal to the outside diameter of the pipe. A soil unit weight of 120 pounds per cubic foot can be used to estimate the prism load on the pipe.

5.5 TRENCHLESS INSTALLATION
A portion of the new pipeline will be installed using trenchless technology. Jack and bore is planned for the portion of the pipeline below the Union Pacific Railroad (UPRR) from South 4th Street in Grover Beach to the Coastal Dunes RV Park in Oceano. Subsurface conditions should be considered to estimate jacking resistance and identify potential impacts to existing

DRAFT Geotechnical Report Project No. 221-539
Central Coast Blue – Conveyance Pipeline July 17, 2023
16 structures and utilities due to settling or heaving of the ground that could be associated with the trenchless installation. The proposed jack and bore method includes jacking and receiving pits that are excavated on either end of the crossing. The boring equipment and casing are installed from within the jacking pit and the casing terminates in the receiving pit. The drilling equipment uses large diameter augers that are mounted to a horizontal drive shaft. Casing is pushed or jacked into the ground as the auger drills and removes the spoils. Additional pieces of casing are welded onto the exposed casing as the bore path advances. This method is typically well suited for soil conditions that can allow temporary stable open faces in dense sand with some clay and/or silt that are above the groundwater table. Design considerations that could impact the proposed trenchless installation are:
• The jack and bore will cross beneath the UPRR right-of-way which is vulnerable to ground movement. UPRR may have specific requirements for utility crossing crossings below their facilities with respect to vertical clearance, casing, and monitoring. It is our understanding that WSC has obtained permits from UPRR for the proposed crossing (WSC 2023b,2023c);
• Existing utilities are present within the 4th Street right-of-way, UPRR right-of-way, and within the Coastal Dunes RV park property. These utilities are also considered vulnerable to ground movement and present a potential obstruction that should be avoided by trenchless installation; and
• Buried structures, tree roots, or other obstructions can significantly impact trenchless operations leading to damage and construction delays caused by obstructions. As-built plans for existing facilities should be reviewed during design.

5.5.1 SUBSURFACE CONDITIONS AND CONSIDERATIONS
The jack and bore crossing below the UPRR will likely be within alluvial flood-plain deposits consisting of very loose to medium dense sand with varying amounts of silt (SP, SM) with trace interbedded layers of medium dense well-graded gravel with sand (GW) and very stiff fat clay (CH). Groundwater was encountered within the borings at 6 to 8.8 feet below the ground surface. The groundwater level in the borings is being periodically monitored as discussed in Section 4.3. Geotechnical consideration for the jack and bore below the UPRR right-of-way include:
• The bore may encounter variable heading within the alluvial flood-plain deposits. Layers of gravel and clay were encountered within the borings performed near the proposed jacking and receiving pit locations and may be encountered in the bore operation. • The heading of the bore operation should be properly supported for sandy ground conditions. Augering equipment should not be advanced beyond the end of the casing to avoid loss of ground within the unsupported sandy overburden soil There is a

DRAFT Geotechnical Report Project No. 221-539
Central Coast Blue – Conveyance Pipeline July 17, 2023
17 potential for the overlying material at the heading to cave or collapse if it is not supported during boring operations.
• Excavation spoils will likely consist of a mixture of fine- and coarse-grained soil of varying consistency and moisture content. Clayey soil may have a tendency to sit on augers or excavation equipment and be difficult to remove (i.e., clogging potential) making advancement of the drive relatively slow.
• The heading pressure should be monitored and limited during advancement of the bore to reduce the potential for heaving of the relatively shallow overburden above the new pipe, UPRR, or adjacent utilities. Jack pressure should be such that earth pressure can be balanced at the heading during the advancement of the pipe and simultaneous excavation of the soil.
• The locations of the existing utilities, and tolerable ground movements for the railroad tracks and utilities should be established before construction so that an appropriate monitoring program can be prepared for the trenchless installation.

5.5.2 JACKING RESISTANCE
The local resistance of the soil to provide resistance for jacking of casings at the crossings will depend upon the condition of the soil at the jacking location as well as the contractor’s methods and equipment. The frictional resistance on the sides of the casing can be reduced by overcutting the heading to a diameter slightly larger than the casing (typically less than 1-inch in diameter larger than the casing), and by applying or introducing lubricants to the outside of the casing, such as slurries or drilling muds.

The reaction force for the jacking equipment will be provided by passive earth pressure from a plate or shoring bearing on the sidewalls of the jacking pit. Soil encountered near the proposed depths of the pipe at the proposed jack and bore location generally consists of very loose to medium dense sand with varying amounts of silt (SP, SM). Soil strength laboratory test results are provided in Appendix B for estimating passive and active values for design of shoring and the jacking apparatus. Any jacking apparatus should be located at least 2 feet below the ground surface. Design should consider groundwater and other soil conditions that are or will be present.

5.5.3 MONITORING
Monitoring for ground surface movements should be provided to assess whether settlement or heaving is impacting the railroad, utilities, and existing improvements as a result of the pipe installation. The project specifications should require the contractor to submit a detailed work plan for the tunneling, casing and pipe installation, and a monitoring program. Project specifications should identify the need for a pre-condition survey with photographs and minimum parameters for monitoring.

DRAFT Geotechnical Report Project No. 221-539
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18 A tolerance for vertical movement above the casing should be established for the tunneling operation (typically no more than ½ inch up or down). The contractor should be responsible for repairing cracks, excessive heave or subsidence, and damage resulting from the tunneling.

5.5.4 CONTACT GROUTING
The overcut annular space and any voids caused by inadvertent over excavation around the outside face of the casing should be filled by grouting upon completion of the jacking operations. Contact grouting is performed within the casing. Grouting equipment and material should be on site before jacking operations begin and should be initiated within 24 hours of completing the casing installation.

6. CONSTRUCTION CONSIDERATIONS

6.1 EXCAVATIONS
Excavations and dewatering for the project are key geotechnical considerations for design and construction. Coordination of excavation and dewatering should be performed by the contractor. Excavations along the pipeline alignment are anticipated to vary from 5 to 13 feet below the ground surface. Excavations for the jack and bore portion of the alignment will be approximately 11 to 13 feet. Maintaining access to local businesses, keeping portions of the roadway open, and safe excavations are key considerations for the design and construction. A summary of anticipated excavation conditions by segment is summarized in Table 4. This data should be used for planning purposes and does not relieve the contractor from performing additional investigations upon which to base their approach to construction.

Table 4: Summary of Anticipated Excavation Conditions
Project
Component
Approximate Station
(WSC 2023)
Anticipated
Depth of
Excavation
(feet BGS) Anticipated Excavation Conditions/Considerations Grover Beach 10+00 to 57+37 5 to 10
Loose to medium dense sand with varying amounts of fines.

Groundwater was not encountered in the borings drilled
along the pipeline alignment and is not expected to be
encountered for this segment.

Jack and Bore
Section of
Pipeline
57+37 to 59+24 10 to 13
Very loose to medium dense sand with varying amounts of fines. Groundwater was encountered in the borings at
depths of 6 to 8.8 feet below the ground surface and is being periodically monitored (see Section 4.3). Unstable
excavations and significant groundwater are anticipated.

Oceano 59+24 to 116+39 5 to 10
Very loose to medium dense sand with varying amounts of fines. Groundwater was encountered in the borings at
depths of 3.3 to 5 feet below the ground surface. Unstable excavations and significant groundwater are anticipated.

DRAFT Geotechnical Report Project No. 221-539
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19 Temporary slopes should be braced or sloped according to the requirements of (Cal) OSHA. We expect the soil within the pipeline alignment will generally consist of very loose to medium dense sands with varying amounts of silt, clay, and gravel which can be classified as Type C soil.

Type C soil can be sloped to 1.5h:1v (horizontal to vertical) for slope heights of up to 20 feet.

The slope inclination used for the construction of temporary slopes should be determined by the contractor’s competent person per OSHA guidelines and the subsurface conditions encountered at the time of construction. Dewatering in advance of the excavation is needed to provide stable conditions at the crossing location and within the segment of the pipeline in Oceano. If dewatering is not performed, the excavation should be shored. Slopes should not be considered stable when excavated below the groundwater table or if there is seepage daylighting on the slopes.

Shoring systems to support temporary slopes typically consist of trench shields, sheet pilings, or braced excavations designed to support the anticipated soil and groundwater conditions and depth of excavation. “Dragging a shield” is a common method of providing worker safety during trenching and construction. However, unless specific provisions exist to place the shield tight against the sidewalls, a shield provides no support for the trench sidewalls and should not be considered an appropriate shoring system for portions of the project where shallow groundwater is present due to the potential for shallow subsurface water and trench collapse.

Shoring systems, such as sheet piling, slurry walls, speed shores with sheeting, jet grouting, or some other form of shoring that actively supports the excavation, should be embedded adequately below the base of the excavation to limit or cutoff groundwater seepage to help maintain a stable excavation base. Embedding the shoring into less permeable layers below the proposed excavations could aid in cutting off the excavations from the surrounding soil and limit the dewatering to within the confines of the shoring system. The contractor should provide a competent person to review excavations and shoring requirements based on the conditions encountered in accordance with OSHA requirements.

6.2 DEWATERING
Groundwater conditions were discussed in Section 4.3 of this report. Groundwater was encountered in borings 23B-09 through 23B-14 at the trenchless crossing and along the Oceano segment of the pipeline at depths of 3.3 to 8.8 feet below the ground surface. Portions of the pipeline in Oceano are adjacent to the Oceano Lagoon and the Pacific Ocean. Dewatering will be needed to lower or control groundwater during construction for the trenchless crossing and along the Oceano segment of the pipeline. Groundwater was not encountered in the borings

DRAFT Geotechnical Report Project No. 221-539
Central Coast Blue – Conveyance Pipeline July 17, 2023
20 located within Grover Beach and dewatering is not anticipated in this portion of the pipeline construction. If present, surface water should be directed away from the trench and be removed where water enters the trench. The Contractor should be prepared to maintain a dry and stable excavation through the duration of construction.

Dewatering systems should be designed by a qualified engineer or hydrogeologist registered with the State of California. Dewatering should be performed in a controlled manner that includes the use of wells, well-points, gravel trenches, or other means of dewatering to lower the water surface elevation within the limits of the planned excavation as needed to provide a stable subgrade for construction. Sumps, well screens, and dewatering pits should be properly filtered such that fines and the surrounding soils are not removed or disturbed by dewatering.

Extracted groundwater should be disposed of in a manner consistent with City, County, and/or State standards.

Dewatering facilities should be installed prior to beginning excavation, with time allowed for lowering of the groundwater table before beginning excavation. Project specifications should indicate that dewatering should be concentrated to lower the groundwater elevation within the footprint of the excavation and only to the depth needed to facilitate construction. Dewatering systems should consider the impact of dewatering on existing improvements and adjacent structures. Secondary dewatering using sumps placed in the bottom of excavations and stabilization of the subgrade may be needed in addition to the initial dewatering. Observation monitoring wells or points should be provided to check that the groundwater has been lowered to a depth of at least 2 feet below the planned depth of excavation prior to beginning excavation. Design and permitting of dewatering systems should also be considered in developing project specifications.

6.3 ADJACENT FACILITIES
The proposed pipeline is being constructed along existing streets bordering homes, local businesses, Oceano Park, and the South San Luis Obispo County Wastewater Treatment Facility, as well as within the Coastal Dunes RV Park. Multiples utilities are present along various segments of the pipeline. Construction along the project may need to consider restricted working hours, additional traffic control and detours, coordination with the County Parks Service and Wastewater Treatment Facility staff, existing adjacent utilities and foundations, or other accommodations.

DRAFT Geotechnical Report Project No. 221-539
Central Coast Blue – Conveyance Pipeline July 17, 2023
21 6.4 EXCAVATION STABILITY
The sidewalls of the trenches could be prone to sloughing and caving during construction or loss of support for adjacent utilities. We recommend that contract documents communicate this potential to the contractors and that bid items include provisions for additional trench backfill and patch paving quantities to account for sloughing and widening of trenches due to the sandy material or the need to support existing utilities during construction.

6.5 SUBGRADE EVALUATION
The geotechnical professional should observe the bottom of excavations to evaluate if the exposed subgrade is suitable for fill placement. The project specifications should provide for review of the subgrade by the geotechnical professional, and for variations in the depth of excavation, if needed, to remove additional loose soil, undocumented fill or debris, or unsuitable material.

6.6 GRADING OBSERVATION
The geotechnical professional should observe grading operations during construction on behalf of the owner to have reasonable certainty that excavation and compaction is being performed according to the recommendations of this report. Field density testing should be performed to help evaluate the compaction and moisture content of the materials being placed.

Fill and aggregates delivered to the site and excavated onsite soil that will be reused as fill or backfill should be sampled and tested for conformance with gradation and quality requirements for the project or submittals reviewed for conformance. The frequency and locations of the tests should be at the discretion of the geotechnical professional. The project specifications should include provisions for the contractor to allow for testing and to provide any shoring, ingress-egress, or traffic control needed to safely perform the testing at the locations and depths needed.

7. LIMITATIONS
This study has been conducted in general accordance with currently accepted geotechnical practices in this area for use by the client for design purposes. The conclusions and recommendations submitted in this report are based upon the data obtained from field reconnaissance, drilling and sampling, and our understanding of the proposed project and type of construction described in this report. If there are any changes in the project or site conditions, Yeh should review those changes and provide additional recommendations if needed. Any modifications to the recommendations of this report or approval of changes made to the project should not be considered valid unless they are made in writing. The report

DRAFT Geotechnical Report Project No. 221-539
Central Coast Blue – Conveyance Pipeline July 17, 2023
22 and drawings contained in this report are intended for design-input and are not intended to act as construction drawings or specifications.

Site conditions will vary between points of observation or sampling, seasonally, and with time.

The nature and extent of subsurface variations across the site may not become evident until excavation is performed. If during construction, fill, soil, or water conditions appear to be different from those described herein, Yeh should be advised and provided the opportunity to evaluate those conditions and provide additional recommendations, if necessary. The geotechnical professional should observe portions of the construction and site conditions, such as excavations, exposed subgrades, and earthwork, to evaluate whether or not the conditions encountered are consistent with those assumed for design, and to provide additional recommendations during construction, if needed.

8.REFERENCES
American Society of Civil Engineers (ASCE 2017). Minimum Design Loads and Associated Criteria for Buildings and other Structures. ASCE Standard 7-16.

American Water Works Association (AWWA 2014), External Corrosion Control for Infrastructure Sustainability, 3rd Edition (Manual for Water Supply Practices M27).

California Department of Transportation (Caltrans 2018), Standard Specifications, Sacramento, California, http://www.dot.ca.gov/hq/dpac/publicat.htm California Geological Survey (CGS 2008). Special Publication 117A, Guidelines for Evaluating and Mitigating Seismic Hazards in California, September 11, 2008.

CalTopo (CalTopo 2023), Online topography tool, accessed July 11, 2023, https://caltopo.com/map.html#ll=35.10181,-120.62433&z=17&b=mbh City of Grover Beach (GB 2006). City of Grover Beach Standards and Specifications. Adopted June 5, 2006.

Cooper, Clark, & Associates (CCA 1979), Foundation Investigation – Proposed Additions, Water Pollution Control District, San Luis Obispo County, dated January 24, 1979, Job No. 2003-A.

Google Earth Pro. (Google Earth 2023). Accessed 2023.

United States Department of the Interior – United States Geological Survey (USGS 2023), Earthquake Hazards Program, Quaternary Fault and Fold Database of the United States, Interactive Fault Map and KML data, accessed July 11, 2023.

DRAFT Geotechnical Report Project No. 221-539
Central Coast Blue – Conveyance Pipeline July 17, 2023
23 United States Department of the Interior – United States Geological Survey (USGS 2004a), Liquefaction-Induced Lateral Spreading in Oceano, California, During the 2003 San Simeon Earthquake, Open-File Report 2004-1269, dated 2004.

United States Department of the Interior – United States Geological Survey (USGS 2004b), Cone Penetration Test Data for San Simeon Earthquake Study, CPT SOC001 through SOC044, accessed July 6, 2023, https://earthquake.usgs.gov/research/cpt/data/ Water Systems Consulting (WSC 2023a), Central Coast Blue Plan and Profile. received via email June 6, 2023.

Water Systems Consulting (WSC 2023b), Central Coast Blue, Union Pacific Rail Road Permit Application, Crossing A, Application ID: 2063173, dated May 19, 2023.

Water Systems Consulting (WSC 2023c), Central Coast Blue, Union Pacific Rail Road Permit Application, Crossing B, Application ID: 2064206, dated May 19, 2023.

Yeh and Associates (Yeh 2020), Geotechnical Report, City of Grover Beach 2020 CDBG Waterline Replacements, Grover Beach, California, Yeh Project No.: 219-477, dated January 30, 2020.

Yeh and Associates (Yeh 2019), Geotechnical Report, South San Luis Obispo County Sanitation District Wastewater Treatment Plant Redundancy Project, 1600 Aloha Avenue, Oceano, California, Yeh Project No.: 216-193, dated January 15, 2019.

PLATEPROJECT NAME:

PROJECT NUMBER:REVISION DATE:
1a
Central Coast Blue
Conveyance Pipeline
Grover Beach, Oceano, CA
221-593 07/11/2023

SUBSURFACE EXPLORATION MAP - NORTH
Geotechnical • Geological • Construction Services
Base Map: Google Earth Pro (February 2023)
Rockaway Ave
Longbranch Ave
ManhaƩan Ave
Seabright Ave
Trouville Ave
Mentone Ave
Nice Ave

PROPOSED ADVANCED

TREATMENT PLANT

LOCATION
(BY OTHERS)
Calvin CtSOC021
SOC020
North
5000
feet
No.

LEGEND:

Boring LocaƟon (Current Study)
Boring LocaƟon (Yeh 2020)
Cone PenetraƟon Test LocaƟon
(USGS 2004)
Proposed Pipeline
No.

All locaƟons and alignments are approximte.

No.
23B-1023B-09
23B-07
23B-06
23B-05
23B-03
23B-01 23B-02
23B-04
23B-08
PLATE 1c
19P-05

PLATEPROJECT NAME:

PROJECT NUMBER:REVISION DATE:
1b
Central Coast Blue
Conveyance Pipeline
Grover Beach, Oceano, CA
221-593 07/11/2023

SUBSURFACE EXPLORATION MAP - SOUTH
Geotechnical • Geological • Construction Services
Base Map: Google Earth Pro (February 2023)

SOUTH SAN

LUIS OBISPO COUNTY

SANITATION DISTRICT

WASTEWATER

TREATMENT FACILITY
OCEANO

AIRPORT
SOC015
23B-12
23B-13
23B-14
2 16E-03
CPT-6
CPT-1
SOC028
SOC027
SOC041
SOC012
SOC011
SOC014
SOC013
SOC016
SOC010
SOC017
SOC001
23B-11
SOC002
SOC003
SOC004
SOC005
North
5000
feet
Boring LocaƟon (Current Study
Boring LocaƟon (Yeh 2019)
Cone PenetraƟon Test LocaƟon (Yeh 2019)
Cone PenetraƟon Test LocaƟon (USGS 2004)
Boring LocaƟon (Cooper, Clark, & Associates 1979)
Sand Boil LocaƟon During 2003 San Simeon
Earthquake (USGS 2004)
Lateral Spread Zone of Extension During 2003 San
Simeon Earthquake (USGS 2004)
Lateral Spread Zone of Compression During 2003 San
Simeon Earthquake (USGS 2004)
Proposed Pipeline
No.

No.

No.

No.

No.

LEGEND:

All locaƟons and alignments are approximate.
ran

PLATEPROJECT NAME:

PROJECT NUMBER:REVISION DATE:
1c
Central Coast Blue
Conveyance Piepline
Grover Beach, Oceano, CA
221-539 7/17/2023
CROSS SECTION A-A’ MAP
Geotechnical • Geological • Construction Services
Base Map: Google Earth Pro (February 2023)

COASTAL DUNES RV PARK
North
500
feet
23B-09 (MW)
23B-10 (MW)
A
A’
No.

LEGEND:

Boring LocaƟon (Current Study)
Cross SecƟon LocaƟon (See Plate 2)
All locaƟons and alignments are approximte.

A A’

PLATEPROJECT NAME:

PROJECT NUMBER: REVISION DATE:

Geotechnical • Geological • Construction Services
2 Central Coast Blue
Conveyance Pipeline
Grover Beach, Oceano, CA
221-539 7/17/2023
SUBSURFACE PROFILE A-A’: TRENCHLESS CROSSING

BORING NUMBER

OFFSET FROM SECTION LINE

EXISTING GROUND SURFACE

FIELD N-VALUE IN BLOWS PER FOOT

LITHOLOGIC CONTACT

USCS SOIL CLASSIFICATION

TOTAL DEPTH EXPLORED
2” OD SPT SAMPLER

BORING DIAGRAM

2.5” OD MODIFED CALIFORNIA

SAMPLER
17B-01
RT. 20’
TD = 30.5’
24 61
GC
CL
MH
MH
MH
MH
MH
MH
7 2
50/6
82 SHELBY TUBE SAMPLER
LEGEND:

Qa
Alluvial Flood Plain Deposits:

Predominantly very loose to medium dense SAND with varying amounts of SILT (SP, SM) with trace layers of medium dense well-graded GRAVEL with SAND and very sƟff fat CLAY (CH)
Interpreted groundwater surface during drilling, queried where uncertain Groundwater level encountered during drilling
Geologic contact, queried where uncertain?
?
See text and logs of exploraƟon for
descripƟon of subsurface condiƟons.

All boundaries and locaƟons are
approximate.

Gravel layer encountered during drilling
Note: Ground surface and proposed improvements from WSC (2023) Central Coast Blue Union Pacific Rail Road Permit ApplicaƟon Crossing B Af ArƟficial Fill
Qoe Old Eolian Deposits:

Loose to very dense poorly graded SAND (SP)
?
?
?
??
Qoe
Qa
?
??
QaQa
Af
Qoe Qoe
1 in. = 20 Ō. verƟcal

PROFILE
1 in. = 20 Ō. horizontal
South 4th Street
UPRR
Coastal Dunes RV Park
Trenchless Jacking Pit
Trenchless Recieving Pit
25 59+00 59+40
25 -15
-35
A’
Southwest
A
Northeast
-15
-35
58+0057+37
55 45 45
23B-09 (MW)
Lt. 136’
TD = ~31’
SP
GW
40 9
SM
10 36
30 21
9 74
90/10”
60 SP
23B-10 (MW)
Lt. 166’
TD = 30.8’
SP 7
3 SM
SM
21 19
34 10
50/6”
46 65
50/3”
CH
SP

APPENDIX A - BORING LOGS

DATE7/7/2023

PROJECT NAME
Central Coast Blue - Conveyance Pipelines
Permeability (ASTM 5084)

SILTY, CLAYEY SAND
Group Names
SC-SM
Graphic / Symbol Graphic / Symbol Group Names
Standard California Sampler (2.5" O.D.)
C
CL
CP
CR
CU
Corrosion, Sulfates, Chlorides (CTM 643; ASTM D4972,ASTM G187, ASTM D4327) Compaction Curve (ASTM D1557)
Direct Shear (ASTM D3080)
Expansion Index (ASTM D4829)
PP
PM
PL
RS Torsional Ring Shear (ASTM D6467)
PI
PA
P
OC
M

GRAVELLY ORGANIC SILT
GRAVELLY ORGANIC SILT with SAND

ORGANIC SILT
Well-graded SAND with CLAY and GRAVEL(or SILTY CLAY and GRAVEL) SILTY, CLAYEY SAND with GRAVEL
CLAYEY SAND with GRAVEL
SILTY SAND with GRAVEL

GROUP SYMBOLS AND NAMES

DRILLING METHOD SYMBOLS
OL
EI
GC
GP
GC-GM

SANDY ORGANIC SILT
Lean CLAY with SAND
Lean CLAY with GRAVEL
SANDY lean CLAY with GRAVEL
ORGANIC lean CLAY
GRAVELLY ORGANIC lean CLAY
GRAVELLY ORGANIC lean CLAY with SAND
Fat CLAY
Elastic SILT with GRAVEL
SANDY elastic SILT
SANDY elastic SILT with GRAVEL
GRAVELLY elastic SILT
GRAVELLY elastic SILT with SAND
ORGANIC elastic SILT
SANDY ORGANIC SILT with GRAVEL
CH
MH
OH
OL/OH
Rock Core Grab Sample
R
Poorly graded SAND with SILT and GRAVEL
SANDY lean CLAY
GRAVELLY lean CLAY
ORGANIC lean CLAY with SAND
ORGANIC lean CLAY with GRAVEL
SANDY ORGANIC lean CLAY
SANDY ORGANIC lean CLAY with GRAVEL
Fat CLAY with SAND
Fat CLAY with GRAVEL
SANDY fat CLAY
SANDY fat CLAY with GRAVEL
GRAVELLY fat CLAY
GRAVELLY fat CLAY with SAND
ORGANIC fat CLAY
ORGANIC fat CLAY with SAND
ORGANIC fat CLAY with GRAVEL
SANDY ORGANIC fat CLAY
Elastic SILT with SAND
Well-graded GRAVEL
Poorly graded GRAVEL with SILT
GRAVELLY lean CLAY with SAND
DS
SP-SC
SW
SP
Piston Sampler
SW-SM
SILTY, CLAYEY GRAVEL with SAND
CLAYEY GRAVEL with SAND
SILTY GRAVEL with SAND
Modified California Sampler (3" O.D.)
GRAVELLY SILT with SAND
SILT
ORGANIC SILT with SAND
ORGANIC SILT with GRAVEL
Liquid Limit, Plastic Limit, Plasticity Index(ASTM D4318) Consolidation (ASTM D2435)
Collapse Potential (ASTM D5333)
Consolidated Undrained Triaxial (ASTM D4767)
Moisture Content (ASTM D2216)
Organic Content (ASTM D2974)
Particle Size Analysis (ASTM D422-63 [2007])
Point Load Index (ASTM D5731)
Standard Penetration Test (SPT) (2" O.D.)
OL
SC
GW
GW-GM
CL
CL-ML
ML
COBBLES and BOULDERS

BOULDERS
PT

SILTY GRAVEL

CLAYEY GRAVEL

SILTY, CLAYEY GRAVEL

SILTY SAND

CLAYEY SAND

SILTY CLAY
SILTY CLAY with SAND
SILTY CLAY with GRAVEL

SANDY SILTY CLAY
SANDY SILTY CLAY with GRAVEL

GRAVELLY SILTY CLAY
GRAVELLY SILTY CLAY with SAND
SILT with SAND
SILT with GRAVEL

SANDY SILT
SANDY SILT with GRAVEL
SANDY ORGANIC fat CLAY with GRAVEL
GRAVELLY ORGANIC fat CLAY
GRAVELLY ORGANIC fat CLAY with SAND
Elastic SILT
ORGANIC elastic SILT with GRAVEL
SANDY elastic ELASTIC SILT

COBBLES
Well-graded GRAVEL with SAND
Well-graded GRAVEL with SILT
Well-graded GRAVEL with CLAY and SAND(or SILTY CLAY and SAND) Well-graded SAND with CLAY (or SILTY CLAY)
Poorly graded GRAVEL
Poorly graded GRAVEL with CLAY(or SILTY CLAY)
Poorly graded SAND with SILT
Poorly graded SAND with CLAY (or SILTY CLAY)
Poorly graded SAND with CLAY and GRAVEL(or SILTY CLAY and GRAVEL) Lean CLAY
ORGANIC elastic SILT with SAND
SANDY ORGANIC elastic SILT with GRAVEL
GRAVELLY ORGANIC elastic SILT
GRAVELLY ORGANIC elastic SILT with SAND
GW-GC
GP-GM
GP-GC
GM
Well-graded SAND with SILT
SW-SC
SP-SM

GRAVELLY SILT

ORGANIC SOIL
ORGANIC SOIL with SAND
ORGANIC SOIL with GRAVEL

SANDY ORGANIC SOIL
SANDY ORGANIC SOIL with GRAVEL

GRAVELLY ORGANIC SOIL
GRAVELLY ORGANIC SOIL with SAND
OH
SM
Auger Drilling

FIELD AND LABORATORY TESTS

WATER LEVEL SYMBOLS
Dynamic Coneor Hand Driven Diamond CoreRotary Drilling
Static Water Level Reading (long-term)
Shelby Tube
Bulk Sample Other (see remarks)
Static Water Level Reading (short-term)
First Water Level Reading (during drilling)
SHEET1 of 1

SAMPLER GRAPHIC SYMBOLS
PEAT
Well-graded GRAVEL with SILT and SAND
Well-graded GRAVEL with CLAY (or SILTY CLAY)
Well-graded SAND
Well-graded SAND with GRAVEL
Well-graded SAND with SILT and GRAVEL
Poorly graded GRAVEL with SAND
Poorly graded GRAVEL with SILT and SAND
Poorly graded GRAVEL with CLAY and SAND(or SILTY CLAY and SAND) Poorly graded SAND
Poorly graded SAND with GRAVEL
Pressure Meter
Pocket Penetrometer
R-Value (CTM 301)
Shrinkage Limit (ASTM D427)
Swell Potential (ASTM D4546)
Unconfined Compression - Soil (ASTM D2166)Unconfined Compression - Rock (ASTM D7012) Unconsolidated Undrained Triaxial(ASTM D2850)
Vane Shear (AASHTO T 223-96 [2004])
-200
VS
UW
UU
UC
Unit Weight (ASTM D4767, ASTM D7263)
200 Wash (ASTM D1140)
TV
SW
SL
SG
SE
Pocket Torvane
Sand Equivalent (CTM 217)
Specific Gravity (AASHTO T 100)

REPORT TITLE

LEGEND FOR SOIL CLASSIFICATION
A-1 of 17

CR (pH = 4.70, r = 13,445 ohm-cm,
SO4
2- = 67 mg/kg, Cl- = 20 mg/kg)
6 6
94 106
4'' ASPHALT CONCRETE.
9'' AGGREGATE BASE.

Poorly graded SAND (SP); medium dense; brown;moist; with mica; (OLD EOLIAN DEPOSITS).

Light brown; with subrounded GRAVEL.

Loose; no gravel.

Bottom of borehole at 11.5 ft bgs
This Boring Record was developed in accordance withthe Caltrans Soil & Rock Logging, Classification, andPresentation Manual (2010) except as noted on the Soilor Rock Legend or below. 100
100
100
5 8
9 5
8 8
6 6
6 20
21 22
BOREHOLE LOCATION (Offset, Station, Line)

8.00' Lt. Sta. 11+68, "IW" Line

DURING DRILLING
Not Encountered

AFTER DRILLING (DATE)

FINAL BY
J. King

DRILL RIG
CME 75

BEGIN DATE
4-5-23

COMPLETION DATE
4-5-23

GROUNDWATERREADINGS

HAMMER TYPE
140-lb Autotrip

DRILLING METHOD
8" Hollow Stem Auger WEATHER NOTES
Sunny, cool
BOREHOLE LOCATION (Lat/Long or North/East and Datum)
--/--
BORING NUMBER23B-01

SURFACE ELEVATION

23.0 ft

BACKFILLED WITH
Native/cement mix; AC patch with rapid
set concrete dyed black
black

LOGGED BY
R. Hooke

DRILLER
2R Drilling

TOTAL DEPTH OF BORING

11.5 ft

LOCATION DESCRIPTION
Rockaway Ave, at entrance to parking lot behind train station Remarks
Sh
e
a
r

S
t
r
e
n
g
t
h
(k
s
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)
Bl
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PROJECT NUMBER221-539
SHEET1 of 1
Mo
i
s
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Co
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e
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t

(
%
)
DE
P
T
H

(
f
t
)
BORING NUMBER23B-01
Dr
y

U
n
i
t

W
e
i
g
h
t
(p
c
f
)

DESCRIPTION
Re
c
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r
y

(
%
)
Ma
t
e
r
i
a
l
Gr
a
p
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s
Bl
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n
.

Dr
i
l
l
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M
e
t
h
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RQ
D

(
%
)
Sa
m
p
l
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N
u
m
b
e
r
PROJECT NAMECentral Coast Blue - Conveyance Pipelines
Ca
s
i
n
g

D
e
p
t
h
EL
E
V
A
T
I
O
N

(
f
t
)
21 19
17 15
13 11
9 7
5 3
1 -1
Sa
m
p
l
e

L
o
c
a
t
i
o
n
REVISION DATE7/7/20235
B
R

-

S
T
A
N
D
A
R
D

2 2
1 -
5 3
9 L
O
G
S

A
N
D

L
A
B
.

G
P
J

C
A
L
I
F
O
R
N
I
A

Y
E
H

L
I
B
R
A
R
Y

(
Y
E
H

V
3 A
P
R
I
L

2 0
2 0
)
.

G
L
B

7 /
1 0
/
2 3
17 16
12 0
1 2
3 4
5 6
7 8
9 10
11 12
13 14
15 16
17 18
19 20
21 22
23 24
25 A-2 of 17

CR (pH = 5.18, r = 14,722 ohm-cm,
SO4
2- = 27 mg/kg, Cl- = 3 mg/kg)CP ( D, MAX = 108 pcf, wOPT = 13%)
7 7
93 94
2'' ASPHALT CONCRETE.
5'' AGGREGATE BASE.

Poorly graded SAND (SP); medium dense; reddishbrown; moist; (OLD EOLIAN DEPOSITS).

Light brown.

Bottom of borehole at 11.5 ft bgs
This Boring Record was developed in accordance withthe Caltrans Soil & Rock Logging, Classification, andPresentation Manual (2010) except as noted on the Soilor Rock Legend or below. 100
100
100
5 8
9 5
7 10
8 13
13 B
23 24
25 BOREHOLE LOCATION (Offset, Station, Line)

9.00' Lt. Sta. 21+30, "IW" Line

DURING DRILLING
Not Encountered

AFTER DRILLING (DATE)

FINAL BY
J. King

DRILL RIG
CME 75

BEGIN DATE
4-5-23

COMPLETION DATE
4-5-23

GROUNDWATERREADINGS

HAMMER TYPE
140-lb Autotrip

DRILLING METHOD
8" Hollow Stem Auger WEATHER NOTES
Sunny, cool
BOREHOLE LOCATION (Lat/Long or North/East and Datum)
--/--
BORING NUMBER23B-02

SURFACE ELEVATION

38.0 ft

BACKFILLED WITH
Native; AC patched with rapid concrete
dyed black

LOGGED BY
R. Hooke

DRILLER
2R Drilling

TOTAL DEPTH OF BORING

11.5 ft

LOCATION DESCRIPTION
Corner of Rockaway Ave and South 5th St
Remarks
Sh
e
a
r

S
t
r
e
n
g
t
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(k
s
f
)
Bl
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PROJECT NUMBER221-539
SHEET1 of 1
Mo
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Co
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n
t

(
%
)
DE
P
T
H

(
f
t
)
BORING NUMBER23B-02
Dr
y

U
n
i
t

W
e
i
g
h
t
(p
c
f
)

DESCRIPTION
Re
c
o
v
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r
y

(
%
)
Ma
t
e
r
i
a
l
Gr
a
p
h
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Bl
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p
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6 i
n
.

Dr
i
l
l
i
n
g

M
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t
h
o
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RQ
D

(
%
)
Sa
m
p
l
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N
u
m
b
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PROJECT NAMECentral Coast Blue - Conveyance Pipelines
Ca
s
i
n
g

D
e
p
t
h
EL
E
V
A
T
I
O
N

(
f
t
)
36 34
32 30
28 26
24 22
20 18
16 14
Sa
m
p
l
e

L
o
c
a
t
i
o
n
REVISION DATE7/7/20235
B
R

-

S
T
A
N
D
A
R
D

2 2
1 -
5 3
9 L
O
G
S

A
N
D

L
A
B
.

G
P
J

C
A
L
I
F
O
R
N
I
A

Y
E
H

L
I
B
R
A
R
Y

(
Y
E
H

V
3 A
P
R
I
L

2 0
2 0
)
.

G
L
B

7 /
1 0
/
2 3
17 17
26 0
1 2
3 4
5 6
7 8
9 10
11 12
13 14
15 16
17 18
19 20
21 22
23 24
25 A-3 of 17

-200 (1% G, 95% S, 5% F)
CR (pH = 6.82, r = 15,679 ohm-cm,SO4
2- = 15 mg/kg, Cl- = 3 mg/kg)
5 94
7'' ASPHALT CONCRETE.

Poorly graded SAND with SILT (SP-SM); loose; darkbrown; moist; (OLD EOLIAN DEPOSITS).

Medium dense; brown; trace angular GRAVEL.

Bottom of borehole at 11.5 ft bgs
This Boring Record was developed in accordance withthe Caltrans Soil & Rock Logging, Classification, andPresentation Manual (2010) except as noted on the Soilor Rock Legend or below. 100
100
100
3 6
7 5
9 13
5 6
7 32
33 34
BOREHOLE LOCATION (Offset, Station, Line)
--

DURING DRILLING
Not Encountered

AFTER DRILLING (DATE)

FINAL BY
J. King

DRILL RIG
CME 75

BEGIN DATE
4-5-23

COMPLETION DATE
4-5-23

GROUNDWATERREADINGS

HAMMER TYPE
140-lb Autotrip

DRILLING METHOD
8" Hollow Stem Auger WEATHER NOTES
Sunny, breezy
BOREHOLE LOCATION (Lat/Long or North/East and Datum)
--/--
BORING NUMBER23B-03

SURFACE ELEVATION

31.2 ft

BACKFILLED WITH
Native/cement mix; AC patch with rapid
set concrete dyed black
black

LOGGED BY
R. Hooke

DRILLER
2R Drilling

TOTAL DEPTH OF BORING

11.5 ft

LOCATION DESCRIPTION
On 4th St, just south of Longbranch Ave
Remarks
Sh
e
a
r

S
t
r
e
n
g
t
h
(k
s
f
)
Bl
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p
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PROJECT NUMBER221-539
SHEET1 of 1
Mo
i
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Co
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t
e
n
t

(
%
)
DE
P
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H

(
f
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)
BORING NUMBER23B-03
Dr
y

U
n
i
t

W
e
i
g
h
t
(p
c
f
)

DESCRIPTION
Re
c
o
v
e
r
y

(
%
)
Ma
t
e
r
i
a
l
Gr
a
p
h
i
c
s
Bl
o
w
s

p
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r

6 i
n
.

Dr
i
l
l
i
n
g

M
e
t
h
o
d
RQ
D

(
%
)
Sa
m
p
l
e

N
u
m
b
e
r
PROJECT NAMECentral Coast Blue - Conveyance Pipelines
Ca
s
i
n
g

D
e
p
t
h
EL
E
V
A
T
I
O
N

(
f
t
)
29 27
25 23
21 19
17 15
13 11
9 7
Sa
m
p
l
e

L
o
c
a
t
i
o
n
REVISION DATE7/7/20235
B
R

-

S
T
A
N
D
A
R
D

2 2
1 -
5 3
9 L
O
G
S

A
N
D

L
A
B
.

G
P
J

C
A
L
I
F
O
R
N
I
A

Y
E
H

L
I
B
R
A
R
Y

(
Y
E
H

V
3 A
P
R
I
L

2 0
2 0
)
.

G
L
B

7 /
1 0
/
2 3
13 22
13 0
1 2
3 4
5 6
7 8
9 10
11 12
13 14
15 16
17 18
19 20
21 22
23 24
25 A-4 of 17

-200 (0% G, 87% S, 13% F)
CR (pH = 6.01, r = 3,828 ohm-cm,
SO4
2- = 7 mg/kg, Cl- = 5 mg/kg)
6 94
1'' ASPHALT CONCRETE.

Poorly graded SAND (SP); loose; dark brown; moist;(OLD EOLIAN DEPOSITS).

SILTY SAND (SM); loose; brown; moist.

Bottom of borehole at 11.5 ft bgs
This Boring Record was developed in accordance withthe Caltrans Soil & Rock Logging, Classification, andPresentation Manual (2010) except as noted on the Soilor Rock Legend or below. 100
100
100
4 4
4 3
4 5
3 4
5 26
27 28
BOREHOLE LOCATION (Offset, Station, Line)

6.00' Lt. Sta. 30+10, "IW" Line

DURING DRILLING
Not Encountered

AFTER DRILLING (DATE)

FINAL BY
J. King

DRILL RIG
CME 75

BEGIN DATE
4-5-23

COMPLETION DATE
4-5-23

GROUNDWATERREADINGS

HAMMER TYPE
140-lb Autotrip

DRILLING METHOD
8" Hollow Stem Auger WEATHER NOTES
Sunny, cool
BOREHOLE LOCATION (Lat/Long or North/East and Datum)
--/--
BORING NUMBER23B-04

SURFACE ELEVATION

27.6 ft

BACKFILLED WITH
Native/cement mix; AC patch with rapid
set concrete dyed black
black

LOGGED BY
R. Hooke

DRILLER
2R Drilling

TOTAL DEPTH OF BORING

11.5 ft

LOCATION DESCRIPTION
Between Seabright Ave and Manhattan Ave
Remarks
Sh
e
a
r

S
t
r
e
n
g
t
h
(k
s
f
)
Bl
o
w
s

p
e
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f
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o
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PROJECT NUMBER221-539
SHEET1 of 1
Mo
i
s
t
u
r
e
Co
n
t
e
n
t

(
%
)
DE
P
T
H

(
f
t
)
BORING NUMBER23B-04
Dr
y

U
n
i
t

W
e
i
g
h
t
(p
c
f
)

DESCRIPTION
Re
c
o
v
e
r
y

(
%
)
Ma
t
e
r
i
a
l
Gr
a
p
h
i
c
s
Bl
o
w
s

p
e
r

6 i
n
.

Dr
i
l
l
i
n
g

M
e
t
h
o
d
RQ
D

(
%
)
Sa
m
p
l
e

N
u
m
b
e
r
PROJECT NAMECentral Coast Blue - Conveyance Pipelines
Ca
s
i
n
g

D
e
p
t
h
EL
E
V
A
T
I
O
N

(
f
t
)
26 24
22 20
18 16
14 12
10 8
6 4
Sa
m
p
l
e

L
o
c
a
t
i
o
n
REVISION DATE7/7/20235
B
R

-

S
T
A
N
D
A
R
D

2 2
1 -
5 3
9 L
O
G
S

A
N
D

L
A
B
.

G
P
J

C
A
L
I
F
O
R
N
I
A

Y
E
H

L
I
B
R
A
R
Y

(
Y
E
H

V
3 A
P
R
I
L

2 0
2 0
)
.

G
L
B

7 /
1 0
/
2 3
8 9
9 0
1 2
3 4
5 6
7 8
9 10
11 12
13 14
15 16
17 18
19 20
21 22
23 24
25 A-5 of 17

CR (pH = 4.52, r = 6,625 ohm-cm,
SO4
2- = 77 mg/kg, Cl- = 5 mg/kg)
6 5
92 90
3'' ASPHALT CONCRETE.
6'' AGGREGATE BASE.

Poorly graded SAND (SP); loose; brown; moist; (OLDEOLIAN DEPOSITS).

Medium dense; light brown.

Bottom of borehole at 11.5 ft bgs
This Boring Record was developed in accordance withthe Caltrans Soil & Rock Logging, Classification, andPresentation Manual (2010) except as noted on the Soilor Rock Legend or below. 100
100
100
4 6
6 6
8 12
6 6
9 29
30 31
BOREHOLE LOCATION (Offset, Station, Line)
--

DURING DRILLING
Not Encountered

AFTER DRILLING (DATE)

FINAL BY
J. King

DRILL RIG
CME 75

BEGIN DATE
4-5-23

COMPLETION DATE
4-5-23

GROUNDWATERREADINGS

HAMMER TYPE
140-lb Autotrip

DRILLING METHOD
8" Hollow Stem Auger WEATHER NOTES
Sunny, breezy
BOREHOLE LOCATION (Lat/Long or North/East and Datum)
--/--
BORING NUMBER23B-05

SURFACE ELEVATION

30.0 ft

BACKFILLED WITH
Native/cement mix; AC patch with rapid
set concrete dyed black
black

LOGGED BY
R. Hooke

DRILLER
2R Drilling

TOTAL DEPTH OF BORING

11.5 ft

LOCATION DESCRIPTION
Remarks
Sh
e
a
r

S
t
r
e
n
g
t
h
(k
s
f
)
Bl
o
w
s

p
e
r

f
o
o
t
PROJECT NUMBER221-539
SHEET1 of 1
Mo
i
s
t
u
r
e
Co
n
t
e
n
t

(
%
)
DE
P
T
H

(
f
t
)
BORING NUMBER23B-05
Dr
y

U
n
i
t

W
e
i
g
h
t
(p
c
f
)

DESCRIPTION
Re
c
o
v
e
r
y

(
%
)
Ma
t
e
r
i
a
l
Gr
a
p
h
i
c
s
Bl
o
w
s

p
e
r

6 i
n
.

Dr
i
l
l
i
n
g

M
e
t
h
o
d
RQ
D

(
%
)
Sa
m
p
l
e

N
u
m
b
e
r
PROJECT NAMECentral Coast Blue - Conveyance Pipelines
Ca
s
i
n
g

D
e
p
t
h
EL
E
V
A
T
I
O
N

(
f
t
)
28 26
24 22
20 18
16 14
12 10
8 6
Sa
m
p
l
e

L
o
c
a
t
i
o
n
REVISION DATE7/7/20235
B
R

-

S
T
A
N
D
A
R
D

2 2
1 -
5 3
9 L
O
G
S

A
N
D

L
A
B
.

G
P
J

C
A
L
I
F
O
R
N
I
A

Y
E
H

L
I
B
R
A
R
Y

(
Y
E
H

V
3 A
P
R
I
L

2 0
2 0
)
.

G
L
B

7 /
1 0
/
2 3
12 20
17 0
1 2
3 4
5 6
7 8
9 10
11 12
13 14
15 16
17 18
19 20
21 22
23 24
25 On 4th St, just north of Trouville Ave
A-6 of 17

CR (pH = 4.11, r = 1,619 ohm-cm,
SO4
2- = 12 mg/kg, Cl- = 14 mg/kg)
-200 (0% G, 95% S, 5% F)
4 4
89 96
6'' ASPHALT CONCRETE.

Poorly graded SAND (SP); loose; brown; moist; (OLDEOLIAN DEPOSITS).

Poorly graded SAND with SILT (SP-SM); loose; brown;moist.

Medium dense; light brown.

Bottom of borehole at 11.5 ft bgs
This Boring Record was developed in accordance withthe Caltrans Soil & Rock Logging, Classification, andPresentation Manual (2010) except as noted on the Soilor Rock Legend or below. 100
100
3 5
6 3
5 9
6 8
8 C
35 36
37 BOREHOLE LOCATION (Offset, Station, Line)
--

DURING DRILLING
Not Encountered

AFTER DRILLING (DATE)

FINAL BY
J. King

DRILL RIG
CME 75

BEGIN DATE
4-5-23

COMPLETION DATE
4-5-23

GROUNDWATERREADINGS

HAMMER TYPE
140-lb Autotrip

DRILLING METHOD
8" Hollow Stem Auger WEATHER NOTES
Sunny, breezy
BOREHOLE LOCATION (Lat/Long or North/East and Datum)
--/--
BORING NUMBER23B-06

SURFACE ELEVATION

39.0 ft

BACKFILLED WITH
Native/cement mix; AC patch with rapid
set concrete dyed black
black

LOGGED BY
R. Hooke

DRILLER
2R Drilling

TOTAL DEPTH OF BORING

11.5 ft

LOCATION DESCRIPTION
29' east of empty lot on Farroll Road
Remarks
Sh
e
a
r

S
t
r
e
n
g
t
h
(k
s
f
)
Bl
o
w
s

p
e
r

f
o
o
t
PROJECT NUMBER221-539
SHEET1 of 1
Mo
i
s
t
u
r
e
Co
n
t
e
n
t

(
%
)
DE
P
T
H

(
f
t
)
BORING NUMBER23B-06
Dr
y

U
n
i
t

W
e
i
g
h
t
(p
c
f
)

DESCRIPTION
Re
c
o
v
e
r
y

(
%
)
Ma
t
e
r
i
a
l
Gr
a
p
h
i
c
s
Bl
o
w
s

p
e
r

6 i
n
.

Dr
i
l
l
i
n
g

M
e
t
h
o
d
RQ
D

(
%
)
Sa
m
p
l
e

N
u
m
b
e
r
PROJECT NAMECentral Coast Blue - Conveyance Pipelines
Ca
s
i
n
g

D
e
p
t
h
EL
E
V
A
T
I
O
N

(
f
t
)
37 35
33 31
29 27
25 23
21 19
17 15
Sa
m
p
l
e

L
o
c
a
t
i
o
n
REVISION DATE7/7/20235
B
R

-

S
T
A
N
D
A
R
D

2 2
1 -
5 3
9 L
O
G
S

A
N
D

L
A
B
.

G
P
J

C
A
L
I
F
O
R
N
I
A

Y
E
H

L
I
B
R
A
R
Y

(
Y
E
H

V
3 A
P
R
I
L

2 0
2 0
)
.

G
L
B

7 /
1 0
/
2 3
11 14
16 0
1 2
3 4
5 6
7 8
9 10
11 12
13 14
15 16
17 18
19 20
21 22
23 24
25 A-7 of 17

GRAVEL in shoe/bottom ring
Suspected drilling in utility trench.

Boring terminated to avoid utilities.
17 104
4'' ASPHALT CONCRETE.
7'' AGGREGATE BASE.

Poorly graded SAND (SP); loose; brown; wet; fine tomedium, subrounded to subangular GRAVEL; backfill;(OLD EOLIAN DEPOSITS).

Bottom of borehole at 5.5 ft bgs
This Boring Record was developed in accordance withthe Caltrans Soil & Rock Logging, Classification, andPresentation Manual (2010) except as noted on the Soilor Rock Legend or below. 1003
4 8
41 BOREHOLE LOCATION (Offset, Station, Line)

0.00' Rt. Sta. 50+43, "IW" Line

DURING DRILLING
Not Encountered

AFTER DRILLING (DATE)

FINAL BY
J. King

DRILL RIG
CME 75

BEGIN DATE
4-5-23

COMPLETION DATE
4-5-23

GROUNDWATERREADINGS

HAMMER TYPE
140-lb Autotrip

DRILLING METHOD
8" Hollow Stem Auger WEATHER NOTES
Cool, breezy
BOREHOLE LOCATION (Lat/Long or North/East and Datum)
--/--
BORING NUMBER23B-07

SURFACE ELEVATION

18.0 ft

BACKFILLED WITH
Native

LOGGED BY
R. Hooke

DRILLER
2R Drilling

TOTAL DEPTH OF BORING

5.5 ft
LOCATION DESCRIPTIONJust south of intersection of Leoni Dr and South 4th St, in shoulder on 4th St
Remarks
Sh
e
a
r

S
t
r
e
n
g
t
h
(k
s
f
)
Bl
o
w
s

p
e
r

f
o
o
t
PROJECT NUMBER221-539
SHEET1 of 1
Mo
i
s
t
u
r
e
Co
n
t
e
n
t

(
%
)
DE
P
T
H

(
f
t
)
BORING NUMBER23B-07
Dr
y

U
n
i
t

W
e
i
g
h
t
(p
c
f
)

DESCRIPTION
Re
c
o
v
e
r
y

(
%
)
Ma
t
e
r
i
a
l
Gr
a
p
h
i
c
s
Bl
o
w
s

p
e
r

6 i
n
.

Dr
i
l
l
i
n
g

M
e
t
h
o
d
RQ
D

(
%
)
Sa
m
p
l
e

N
u
m
b
e
r
PROJECT NAMECentral Coast Blue - Conveyance Pipelines
Ca
s
i
n
g

D
e
p
t
h
EL
E
V
A
T
I
O
N

(
f
t
)
16 14
12 10
8 6
4 2
0 -2
-4
-6
Sa
m
p
l
e

L
o
c
a
t
i
o
n
REVISION DATE7/7/20235
B
R

-

S
T
A
N
D
A
R
D

2 2
1 -
5 3
9 L
O
G
S

A
N
D

L
A
B
.

G
P
J

C
A
L
I
F
O
R
N
I
A

Y
E
H

L
I
B
R
A
R
Y

(
Y
E
H

V
3 A
P
R
I
L

2 0
2 0
)
.

G
L
B

7 /
1 0
/
2 3
12 0
1 2
3 4
5 6
7 8
9 10
11 12
13 14
15 16
17 18
19 20
21 22
23 24
25 A-8 of 17

-200 (1% G, 82% S, 18% F)
6 9
102
99 Poorly graded SAND (SP); loose; dark brown; moist;(OLD EOLIAN DEPOSITS).

SILTY SAND (SM); loose; brown; moist.

Well-graded SAND (SW); medium dense; brown; moistto wet.

Bottom of borehole at 11.5 ft bgs
This Boring Record was developed in accordance withthe Caltrans Soil & Rock Logging, Classification, andPresentation Manual (2010) except as noted on the Soilor Rock Legend or below. 100
100
100
4 5
6 3
4 6
4 8
10 38
39 40
BOREHOLE LOCATION (Offset, Station, Line)
--

DURING DRILLING
Not Encountered

AFTER DRILLING (DATE)

FINAL BY
J. King

DRILL RIG
CME 75

BEGIN DATE
4-5-23

COMPLETION DATE
4-5-23

GROUNDWATERREADINGS

HAMMER TYPE
140-lb Autotrip

DRILLING METHOD
8" Hollow Stem Auger WEATHER NOTES
Sunny, cool
BOREHOLE LOCATION (Lat/Long or North/East and Datum)
--/--
BORING NUMBER23B-08

SURFACE ELEVATION

25.0 ft

BACKFILLED WITH
Native

LOGGED BY
R. Hooke

DRILLER
2R Drilling

TOTAL DEPTH OF BORING

11.5 ft

LOCATION DESCRIPTION
On intersection of Barca St and Leoni Dr, in pullout
Remarks
Sh
e
a
r

S
t
r
e
n
g
t
h
(k
s
f
)
Bl
o
w
s

p
e
r

f
o
o
t
PROJECT NUMBER221-539
SHEET1 of 1
Mo
i
s
t
u
r
e
Co
n
t
e
n
t

(
%
)
DE
P
T
H

(
f
t
)
BORING NUMBER23B-08
Dr
y

U
n
i
t

W
e
i
g
h
t
(p
c
f
)

DESCRIPTION
Re
c
o
v
e
r
y

(
%
)
Ma
t
e
r
i
a
l
Gr
a
p
h
i
c
s
Bl
o
w
s

p
e
r

6 i
n
.

Dr
i
l
l
i
n
g

M
e
t
h
o
d
RQ
D

(
%
)
Sa
m
p
l
e

N
u
m
b
e
r
PROJECT NAMECentral Coast Blue - Conveyance Pipelines
Ca
s
i
n
g

D
e
p
t
h
EL
E
V
A
T
I
O
N

(
f
t
)
23 21
19 17
15 13
11 9
7 5
3 1
Sa
m
p
l
e

L
o
c
a
t
i
o
n
REVISION DATE7/7/20235
B
R

-

S
T
A
N
D
A
R
D

2 2
1 -
5 3
9 L
O
G
S

A
N
D

L
A
B
.

G
P
J

C
A
L
I
F
O
R
N
I
A

Y
E
H

L
I
B
R
A
R
Y

(
Y
E
H

V
3 A
P
R
I
L

2 0
2 0
)
.

G
L
B

7 /
1 0
/
2 3
11 10
18 0
1 2
3 4
5 6
7 8
9 10
11 12
13 14
15 16
17 18
19 20
21 22
23 24
25 A-9 of 17

3 4
5 4
5 5
13 18
18 3
13 17
7 10
11 16
18 22
20 24
50/6"
10 10
20 22
100
120
104
104
100
0 100
100
0 100
100
3'' ASPHALT CONCRETE.

Poorly graded SAND (SP); loose;brown; moist; (ALLUVIALFLOOD-PLAIN DEPOSITS).

Well-graded GRAVEL with SAND(GW); medium dense; brown; wet.

SILTY SAND (SM); medium dense;light brown; moist; clay seam, rootlets.

Some GRAVEL.

Poorly graded SAND (SP); dense; lightbrown; moist; dense to very dense;(OLD EOLIAN DEPOSITS). 1 -
2 3
-
4 5
No recovery
PA (53% G, 41% S, 1% F)
DS
No recovery
PA (2% G, 76% S, 20% F)
CR (pH = 6.70, r = 2,797 ohm-cm,SO4
2- = 19 mg/kg, Cl- = 7 mg/kg)
P
2" Solid
Pipe,Grout

0.02"
SlottedPipe
Bentonite
Plug
#3 Sand

TOTAL DEPTH OF BORING

31.0 ft
BORING NUMBER23B-09

FINAL BY
J. King

DRILLER
2R Drilling

DRILL RIG
CME 75

WEATHER NOTES
Sunny, chilly

BACKFILLED WITH
Monitoring Well

AFTER DRILLING (DATE)DURING DRILLING

6.0 ft

SURFACE ELEVATION

19.0 ft

GROUNDWATER

READINGS

LOGGED BY
R. Hooke

DRILLING METHOD
8" Hollow Stem Auger

HAMMER TYPE
140-lb Autotrip

COMPLETION DATE
4/4/23

BEGIN DATE
4/4/23
BOREHOLE LOCATION (Lat/Long or North/East and Datum)
--/--
BOREHOLE LOCATION (Offset, Station, Line)
136.00' Lt. Sta. 58+87, "IW" Line

LOCATION DESCRIPTION
In Coastal Dunes RV Park, behind site 20
PROJECT NAMECentral Coast Blue - Conveyance Pipelines
PROJECT NUMBER221-539
BORING NUMBER23B-09
(continued)
SHEET1 of 2
Ma
t
e
r
i
a
l
Gr
a
p
h
i
c
s
DE
P
T
H

(
f
t
)
RQ
D

(
%
)
EL
E
V
A
T
I
O
N

(
f
t
)
17 15
13 11
9 7
5 3
1 -1
-3
-5
Bl
o
w
s

p
e
r

6 i
n
.

Mo
i
s
t
u
r
e
Co
n
t
e
n
t

(
%
)
Dr
y

U
n
i
t

W
e
i
g
h
t
(p
c
f
)
Dr
i
l
l
i
n
g

M
e
t
h
o
d
Re
c
o
v
e
r
y

(
%
)

DESCRIPTION
Sa
m
p
l
e

o
r

R
u
n
Lo
c
a
t
i
o
n
REVISION DATE7/7/2023
Sa
m
p
l
e

o
r
Ru
n

N
u
m
b
e
r
Remarks
We
l
l

D
i
a
g
r
a
m
We
l
l

D
e
s
c
r
i
p
t
i
o
n
Sh
e
a
r

S
t
r
e
n
g
t
h
(k
s
f
)
Bl
o
w
s

p
e
r

f
o
o
t
5 B
R

-

S
T
A
N
D
A
R
D

W
I
T
H

M
O
N
I
T
O
R
I
N
G

W
E
L
L

2 2
1 -
5 3
9 L
O
G
S

A
N
D

L
A
B
.

G
P
J

C
A
L
I
F
O
R
N
I
A

Y
E
H

L
I
B
R
A
R
Y

(
Y
E
H

V
3 A
P
R
I
L

2 0
2 0
)
.

G
L
B

7 /
1 2
/
2 3
9 10
36 30
21 40
74 0
1 2
3 4
5 6
7 8
9 10
11 12
13 14
15 16
17 18
19 20
21 22
23 24
25 A-10 of 17

3 4
5 28
40 50/4"
6 17
43 23
7 101
113
100
83 100
Loose.Poorly graded SAND (SP) (continued).

Very dense.

Dense.

Bottom of borehole at 31.0 ft bgs
This Boring Record was developed inaccordance with the Caltrans Soil &Rock Logging, Classification, andPresentation Manual (2010) except asnoted on the Soil or Rock Legend orbelow. 6 7
8 Bottom
of Well#3 Sand
PROJECT NAMECentral Coast Blue - Conveyance Pipelines
PROJECT NUMBER221-539
BORING NUMBER23B-09
SHEET2 of 2
Ma
t
e
r
i
a
l
Gr
a
p
h
i
c
s
DE
P
T
H

(
f
t
)
RQ
D

(
%
)
EL
E
V
A
T
I
O
N

(
f
t
)
-7
-9
-11
-13
-15
-17
-19
-21
-23
-25
-27
-29
-31
-33
-35
Bl
o
w
s

p
e
r

6 i
n
.

Mo
i
s
t
u
r
e
Co
n
t
e
n
t

(
%
)
Dr
y

U
n
i
t

W
e
i
g
h
t
(p
c
f
)
Dr
i
l
l
i
n
g

M
e
t
h
o
d
Re
c
o
v
e
r
y

(
%
)

DESCRIPTION
Sa
m
p
l
e

o
r

R
u
n
Lo
c
a
t
i
o
n
REVISION DATE7/7/2023
Sa
m
p
l
e

o
r
Ru
n

N
u
m
b
e
r
Remarks
We
l
l

D
i
a
g
r
a
m
We
l
l

D
e
s
c
r
i
p
t
i
o
n
Sh
e
a
r

S
t
r
e
n
g
t
h
(k
s
f
)
Bl
o
w
s

p
e
r

f
o
o
t
5 B
R

-

S
T
A
N
D
A
R
D

W
I
T
H

M
O
N
I
T
O
R
I
N
G

W
E
L
L

2 2
1 -
5 3
9 L
O
G
S

A
N
D

L
A
B
.

G
P
J

C
A
L
I
F
O
R
N
I
A

Y
E
H

L
I
B
R
A
R
Y

(
Y
E
H

V
3 A
P
R
I
L

2 0
2 0
)
.

G
L
B

7 /
1 2
/
2 3
9 90/10"
60 25
26 27
28 29
30 31
32 33
34 35
36 37
38 39
40 41
42 43
44 45
46 47
48 49
50 51
52 53
54 55
A-11 of 17

3 3
4 1
1 2
8 10
11 8
8 11
8 13
21 3
4 6
21 50/6"
7 17
29 100
107
92 100
100
100
100
100
100
0 Poorly graded SAND (SP); loose; darkbrown; moist; (ALLUVIALFLOOD-PLAIN DEPOSITS).

Very loose; reddish brown.

SILTY SAND (SM); medium dense;brown; moist; some fine to medium,subrounded to subangular GRAVEL.

Wet.

Fat CLAY (CH); very stiff; reddishbrown; wet.

SILTY SAND (SM); loose; brown; wet;trace fine GRAVEL.
42 43
44 45
46 47
-
CR (pH = 5.29, r = 898 ohm-cm,
SO4
2- = 83 mg/kg, Cl- = 28 mg/kg)
DS
PA (10% G, 53% S, 29% F)
DS
PA (7% G, 71% S, 21% F)
No recovery
2" Solid
Pipe,Grout
Bentonite
Plug
#3 Sand

0.02"
SlottedPipe

TOTAL DEPTH OF BORING

30.8 ft
BORING NUMBER23B-10

FINAL BY
J. King

DRILLER
2R Drilling

DRILL RIG
CME 75

WEATHER NOTES
Chilly, clear

BACKFILLED WITH
Monitoring Well

AFTER DRILLING (DATE)DURING DRILLING

8.5 ft

SURFACE ELEVATION

20.6 ft

GROUNDWATER

READINGS

LOGGED BY
R. Hooke

DRILLING METHOD
8" Hollow Stem Auger

HAMMER TYPE
140-lb Autotrip

COMPLETION DATE
4/6/23

BEGIN DATE
4/6/23
BOREHOLE LOCATION (Lat/Long or North/East and Datum)
--/--
BOREHOLE LOCATION (Offset, Station, Line)
166.00' Lt. Sta. 57+67, "IW" Line

LOCATION DESCRIPTION
On South 4th St, in pullout near railroad tracks
PROJECT NAMECentral Coast Blue - Conveyance Pipelines
PROJECT NUMBER221-539
BORING NUMBER23B-10
(continued)
SHEET1 of 2
Ma
t
e
r
i
a
l
Gr
a
p
h
i
c
s
DE
P
T
H

(
f
t
)
RQ
D

(
%
)
EL
E
V
A
T
I
O
N

(
f
t
)
19 17
15 13
11 9
7 5
3 1
-1
-3
Bl
o
w
s

p
e
r

6 i
n
.

Mo
i
s
t
u
r
e
Co
n
t
e
n
t

(
%
)
Dr
y

U
n
i
t

W
e
i
g
h
t
(p
c
f
)
Dr
i
l
l
i
n
g

M
e
t
h
o
d
Re
c
o
v
e
r
y

(
%
)

DESCRIPTION
Sa
m
p
l
e

o
r

R
u
n
Lo
c
a
t
i
o
n
REVISION DATE7/7/2023
Sa
m
p
l
e

o
r
Ru
n

N
u
m
b
e
r
Remarks
We
l
l

D
i
a
g
r
a
m
We
l
l

D
e
s
c
r
i
p
t
i
o
n
Sh
e
a
r

S
t
r
e
n
g
t
h
(k
s
f
)
Bl
o
w
s

p
e
r

f
o
o
t
5 B
R

-

S
T
A
N
D
A
R
D

W
I
T
H

M
O
N
I
T
O
R
I
N
G

W
E
L
L

2 2
1 -
5 3
9 L
O
G
S

A
N
D

L
A
B
.

G
P
J

C
A
L
I
F
O
R
N
I
A

Y
E
H

L
I
B
R
A
R
Y

(
Y
E
H

V
3 A
P
R
I
L

2 0
2 0
)
.

G
L
B

7 /
1 2
/
2 3
7 3
21 19
34 10
50/6"
0 1
2 3
4 5
6 7
8 9
10 11
12 13
14 15
16 17
18 19
20 21
22 23
24 25
A-12 of 17

11 20
26 17
25 40
23 50/3"
24 101
100
100
100
Dense; no GRAVEL.SILTY SAND (SM) (continued).

Poorly graded SAND (SP); dense;brown; wet; (OLD EOLIANDEPOSITS).

Very dense.

Bottom of borehole at 30.8 ft bgs
This Boring Record was developed inaccordance with the Caltrans Soil &Rock Logging, Classification, andPresentation Manual (2010) except asnoted on the Soil or Rock Legend orbelow. 48 49
50 CR (pH = 6.79, r = 898 ohm-cm,
SO4
2- = 22 mg/kg, Cl- = 10 mg/kg)
P
Bottom
of Well#3 Sand
PROJECT NAMECentral Coast Blue - Conveyance Pipelines
PROJECT NUMBER221-539
BORING NUMBER23B-10
SHEET2 of 2
Ma
t
e
r
i
a
l
Gr
a
p
h
i
c
s
DE
P
T
H

(
f
t
)
RQ
D

(
%
)
EL
E
V
A
T
I
O
N

(
f
t
)
-5
-7
-9
-11
-13
-15
-17
-19
-21
-23
-25
-27
-29
-31
-33
Bl
o
w
s

p
e
r

6 i
n
.

Mo
i
s
t
u
r
e
Co
n
t
e
n
t

(
%
)
Dr
y

U
n
i
t

W
e
i
g
h
t
(p
c
f
)
Dr
i
l
l
i
n
g

M
e
t
h
o
d
Re
c
o
v
e
r
y

(
%
)

DESCRIPTION
Sa
m
p
l
e

o
r

R
u
n
Lo
c
a
t
i
o
n
REVISION DATE7/7/2023
Sa
m
p
l
e

o
r
Ru
n

N
u
m
b
e
r
Remarks
We
l
l

D
i
a
g
r
a
m
We
l
l

D
e
s
c
r
i
p
t
i
o
n
Sh
e
a
r

S
t
r
e
n
g
t
h
(k
s
f
)
Bl
o
w
s

p
e
r

f
o
o
t
5 B
R

-

S
T
A
N
D
A
R
D

W
I
T
H

M
O
N
I
T
O
R
I
N
G

W
E
L
L

2 2
1 -
5 3
9 L
O
G
S

A
N
D

L
A
B
.

G
P
J

C
A
L
I
F
O
R
N
I
A

Y
E
H

L
I
B
R
A
R
Y

(
Y
E
H

V
3 A
P
R
I
L

2 0
2 0
)
.

G
L
B

7 /
1 2
/
2 3
46 65
50/3"
25 26
27 28
29 30
31 32
33 34
35 36
37 38
39 40
41 42
43 44
45 46
47 48
49 50
51 52
53 54
55 A-13 of 17

No recovery
CR (pH = 5.21, r = 206 ohm-cm,
SO4
2- = 7,877 mg/kg, Cl- = 171mg/kg)
176 28
5'' ASPHALT CONCRETE.

Poorly graded SAND (SP); medium dense; dark brown;moist; with mica; (ARTIFICIAL FILL).

PEAT (PT); very loose; gray; very moist; (ALLUVIALFLOOD-PLAIN DEPOSITS).

Poorly graded SAND (SP); medium dense; gray; wet;with rootlets.

Bottom of borehole at 11.5 ft bgs
This Boring Record was developed in accordance withthe Caltrans Soil & Rock Logging, Classification, andPresentation Manual (2010) except as noted on the Soilor Rock Legend or below. 0 100
100
4 8
12 2
3 2
3 4
9 -
9 10
BOREHOLE LOCATION (Offset, Station, Line)

10.00' Rt. Sta. 66+22, "IW" Line

DURING DRILLING
Not Encountered

AFTER DRILLING (DATE)

5.5 ft on4-4-23

FINAL BY
J. King

DRILL RIG
CME 75

BEGIN DATE
4-4-23

COMPLETION DATE
4-4-23

GROUNDWATERREADINGS

HAMMER TYPE
140-lb Autotrip

DRILLING METHOD
8" Hollow Stem Auger WEATHER NOTES
Sunny, breezy
BOREHOLE LOCATION (Lat/Long or North/East and Datum)
--/--
BORING NUMBER23B-11

SURFACE ELEVATION

10.0 ft

BACKFILLED WITH
Native; AC patched with rapid concrete
dyed black

LOGGED BY
R. Hooke

DRILLER
2R Drilling

TOTAL DEPTH OF BORING

11.5 ft

LOCATION DESCRIPTION
Corner of Coolidge Dr and Norswing Dr
Remarks
Sh
e
a
r

S
t
r
e
n
g
t
h
(k
s
f
)
Bl
o
w
s