\\eureka\projects\2020\020143-FortunaNPDES\210-Geotech\PUBS\rpts\20250718-GeotechDataRpt-WWTP.docx through SCPT-3, were advanced to depths ranging from 36 feet to 50 feet below the ground surface. The final depth of the individual probes were limited by effective refusal within very dense and presumably highly consolidated sand and gravel.
The CPT method involves advancing a nominal 1.7-inch diameter conical-shaped probe equipped with sensors into the subsurface using a hydraulic ram system. The probe measures a continuous record of tip resistance, sleeve friction, and pore pressure as the cone is advanced. The collective data allows for determination of a soil behavior type (SBT) based on comparison of the tip resistance to the friction ratio.
The CPT cone and rig were equipped with a geophone and automatic energy source, respectively, to measure soil shear wave velocities. During cone advancement at the location of SCPT-3, seismic shear wave velocities were recorded every 5 feet, beginning at a depth of 10 feet, to the final depth. The shear wave velocity measurements provide for a determination of the soil site class as well as providing information regarding dynamic soil properties to estimate site response and liquefaction potential during the design earthquake.
3.0 Site Conditions
3.1 Geology
Geologic conditions at the site were evaluated based on a review of publicly available information including the “Geologic Map of the Eel River Valley Area, Humboldt County, California” (Ogle, 1953), and the “Geology and Geomorphic Features Related to Landsliding, Fortuna 7.5’ Quadrangle, Humboldt County, California” (CDMG, 1985). Based on these publications and an assessment of the soil profile encountered during our field exploration, we interpret the project site to be predominantly underlain by overbank flood deposits and stream channel deposits. Overlying the fluvial deposits is a thin veneer of artificial fill that was placed during the initial construction of the site.
The following are the general descriptions of the geologic units as shown in the geologic map. • Artificial fill - recent in age; man-made or intensively man-modified soil or sediments that widely varies in relative stability.
• Alluvium - Holocene age; unconsolidated sand, silt, gravel, and clay deposited by streams; correlates to Old Alluvium of Ogle used to identify the most recent floodplain deposits, which are now being re-incised by the present-day Eel River. The sediments differ from young alluvium in that they are no longer being actively deposited. The material is predominantly composed of sand and gravel, overlain by fine-grained over-bank and flood deposits composed of clay and silt.
3.2 Soil Properties
The SBT profile determined from the CPT soundings indicates the subsurface materials at the site to consist of soft to medium stiff clay and silty clay to a depth of about 30 feet (±). Below this depth the soils abruptly transition to dense to very dense sand and silty sand. Refusal of the probe occurred at Jacobs
Geotechnical Investigation Data Report – Fortuna WWTP, 180 Dinsmore Drive, Fortuna, CA July 18, 2025
\\eureka\projects\2020\020143-FortunaNPDES\210-Geotech\PUBS\rpts\20250718-GeotechDataRpt-WWTP.docx depths of 36 feet to 50 feet due to either excessively high tip resistance and/or significant deviation of the cone from vertical due to the presence of gravel.
3.3 Groundwater
Pore pressure dissipation tests conducted during the current site investigation in April 2025 indicate the depth to the static groundwater surface to be 7.5 feet to 8.5 feet below the ground surface. Previous field investigations conducted by SHN at the site in June 1995 and August 2003 indicated the depth to groundwater to be approximately 6 feet to 13 feet below the ground surface.
It generally should be expected that free groundwater and/or wet soil conditions will be encountered within any excavation greater than about 7 feet below existing site grades at the locations of the proposed improvements. Caving conditions and the rapid inflow of water should be anticipated for all excavations that extend below the groundwater surface elevation. Measures to control the flow of groundwater during excavation and construction should be implemented on an as needed basis by the Contractor.
4.0 Evaluation of Seismic Hazards
4.1 Seismicity
Based on the record of historical earthquake, coastal northwestern California is considered one of the most seismically active regions in the continental United States. The Eel River Valley and Humboldt Bay regions in particular occupy a complex geologic environment characterized by very high rates of active tectonic deformation and seismicity due to the interaction of multiple plate boundaries in the location of the Mendocino triple junction (MTJ).
The Little Salmon fault (LSF) is the closest active fault to the site and is located approximately 2 miles northeast of the project site (CDMG, 1985; CGS, 2002; Hart and Bryant, 2007). The LSF is a northweststriking and northeast-dipping thrust fault located in both the onshore and offshore portions of the CSZ fold and thrust belt. The upper-bound earthquake considered capable of being generated by the LSF has an estimated moment magnitude (Mw) of 7.0 or greater (CDMG/USGS, 1996).
In addition to the LSF, there are several other local sources capable of producing strong seismic shaking at the project site (Dengler and others, 1992). These sources include:
The Cascadia Subduction Zone. North of the MTJ, the Gorda plate is being actively subducted beneath North America along the Cascadia Subduction Zone (CSZ). The CSZ represents the most significant seismic source in the north coast region. A great subduction event has a potential rupture length of up to 700 miles extending from Cape Mendocino in the south to British Columbia in the north and would be accompanied by extensive tsunami inundation in low-lying coastal areas. Paleoseismic studies along the subduction zone suggest that great earthquakes are generated along the CSZ every 300 to 500 years with 13 known events having occurred in the previous 6,000 years. The last large subduction earthquake occurred in January 1700 (Personius and Nelson, 2005). Rupture along the entire CSZ boundary is Jacobs
Geotechnical Investigation Data Report – Fortuna WWTP, 180 Dinsmore Drive, Fortuna, CA July 18, 2025
\\eureka\projects\2020\020143-FortunaNPDES\210-Geotech\PUBS\rpts\20250718-GeotechDataRpt-WWTP.docx estimated to produce earthquakes of Mw 9 or greater (CDMG/USGS, 1996) and would generate long duration, very strong ground shaking at the project site. 1) The Gorda Plate. Gorda plate earthquakes account for most of the historical seismicity. These earthquakes occur primarily offshore along left lateral faults and are generated by internal deformation within the plate as it moves toward the subduction zone. Significant historical Gorda plate earthquakes have ranged in magnitude from Mw 5 to Mw 7. 2) The Mendocino Fault. The Mendocino fault is the second most frequent source of earthquakes in the region. The fault represents the plate boundary between the Gorda and Pacific plates and is capable of generating right-lateral strike-slip displacement such as that which occurred most recently in December 2024. Historic Mendocino fault events have ranged from Mw 5 to Mw 7.5. 3) The northern segment of the San Andreas Fault. The northern San Andreas fault (SAF) is a right lateral strike-slip fault that forms the boundary between the Pacific and North American plates beginning north of San Francisco and continuing approximately 250 miles to the MTJ. The SAF projects offshore north of Point Arena in Mendocino County and continues northwest where it comes back onshore at Shelter Cove in southern Humboldt County before terminating at the MTJ near the town of Petrolia. The 1906 Great San Francisco Earthquake (Mw 8.3) was the result of rupture along the entire northern segment of the SAF from Marin County to Humboldt County causing some of the most significant damage in the north coast region.
4.2 Strong Ground Shaking
As discussed above, the project site will be subjected to long duration and strong ground shaking in the event of an earthquake along the CSZ or any of the other local seismic sources. Given the proximity of the site to these active seismic sources, the probability that strong ground shaking associated with moderate to large magnitude earthquakes will occur during the design life of the proposed improvements is considered very high. This hazard however is common in Northern California and the effects of ground shaking can be mitigated by designing and constructing new structures in conformance with current building codes and engineering practices. Ground acceleration parameters related to seismic design of the proposed improvements are presented in Section 5.0.
4.3 Surface Fault Rupture
The project site is not located within an Alquist-Priolo Earthquake Fault Zone as shown in the State of California Special Studies Zones Fortuna Quadrangle (CDMG, 1991). Based on our field reconnaissance of the site and vicinity, and a review of available geologic maps, historical aerial photographs, and light detection and ranging (LiDAR) imagery, we found no geomorphic evidence to suggest that a fault lineament projects through the site. Therefore, the potential for surface fault rupture to occur at the project site is considered remote.
Jacobs
Geotechnical Investigation Data Report – Fortuna WWTP, 180 Dinsmore Drive, Fortuna, CA July 18, 2025
\\eureka\projects\2020\020143-FortunaNPDES\210-Geotech\PUBS\rpts\20250718-GeotechDataRpt-WWTP.docx
5.0 Code Based Seismic Design Criteria
The geotechnical-related parameters to be used for seismic design of the proposed improvements were determined in accordance with American Society of Civil Engineers and Structural Engineering Institute (ASCE/SEI) 7-16 Minimum Design Loads for Building and Other Structures (ASCE/SEI, 2017). Tables 1 and 2 summarize the code-based design criteria obtained in accordance with Chapter 16 Structural Design, Section 1613 Earthquake Loads contained in the most recent edition of the California Building Code, (CBC, 2022). Based on the measured shear wave velocities for the soil profile, we classify the subgrade as a Site Class D (Stiff Soil). Presented in Table 1 are the recommended design criteria for the risk-targeted maximum considered earthquake (MCER) obtained from the ASCE Hazard Tool website (ASCE, 2025) for the project site location (40.591215° N latitude and -124.158203° W longitude) based on the Site Class and Risk Category (IV).
Table 1. California Building Code Seismic Design Parameters Parameter Value 2022 CBC a Reference
Site Class D Table 1613.2.2
Maximum Considered Earthquake (MCER) Ground Motion Spectral Response Acceleration-Site Class B (short, 0.2 sec; SS)
2.131 Figure 1613.3.1(1)
MCER Ground Motion Spectral Response Acceleration-Site Class B (1 sec; S1)
1.077 Figure 1613.3.1(2)
Site Coefficient (Fa) 1.0 Table 1613.2.3(1)
Site Coefficient (Fv) N/A b Table 1613.2.3(2)
MCER Spectral Response Acceleration Adjusted for Site Class Effects (short, 0.2 sec; SMS)
2.131 Section 1613.2.3 (Eqn. 16-20)
MCER Spectral Response Acceleration Adjusted for Site Class Effects (1 sec; SM1)
N/A Section 1613.2.3 (Eqn. 16-21)
5% Damped Design Spectral Response Acceleration
(short, 0.2 sec; SDS)
1.421 Section 1613.2.4 (Eqn. 16-22)
5% Damped Design Spectral Response Acceleration (1 sec; SD1) N/A Section 1613.2.4 (Eqn. 16-23) a. CBC: California Building Code
b. N/A: not applicable
Table 2 presents the mapped maximum considered geometric mean (MCEG) seismic design parameters in accordance with ASCE 7-16.
Table 2. American Society of Civil Engineers 7-16 Peak Ground Accelerations Parameter Value ASCE a 7-16 Reference
Seismic Design Category N/A b Tables 11.6-1 and 11.6-2
Mapped Maximum Considered Earthquake (MCEG) Peak Ground Acceleration, (PGA) 0.997 Figure 22-7
Site Coefficient (FPGA) 1.1 Table 11.8-1
MCEG Peak Ground Acceleration Adjusted for Site Class Effects, (PGAM) 1.097 Section 11.8.3 (Eqn. 11.8-1)
a. ASCE: American Society of Civil Engineers
b. N/A: not applicable
Jacobs
Geotechnical Investigation Data Report – Fortuna WWTP, 180 Dinsmore Drive, Fortuna, CA July 18, 2025
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6.0 Limitations
The information presented in this report are based upon interpretation of data obtained from SHN’s test locations and on general field observations made during our site investigation. Subsurface exploration of any site is necessarily confined to selected locations and subsurface conditions may, and usually do, vary between and around these locations. Any person associated with this project who observes conditions or features of the site or its surrounding areas that are different from those described in the report should report them immediately to SHN for evaluation. If varied conditions come to light during project development, SHN should be given the opportunity to evaluate the need for additional exploration, testing, or analysis.
This report was prepared in accordance with the generally accepted standards of geotechnical engineering practice in Humboldt County at the time this report was written. No other warranty, express or implied, is made. It is the owner’s responsibility to see that all parties to the project, including the designers, contractors, and subcontractors, are made aware of this report in its entirety.
If you have any comments regarding the findings contained in this report, please contact me at [email protected].
SHN
Signed 7/18/25
Giovanni Vadurro, CEG 2554
Engineering Geologist
Attachments: 1. Cone Penetration Testing (CPT) Report
References
American Society of Civil Engineers and Structural Engineering Institute. (2017). “ASCE/SEI 7-16: Minimum Design Loads for Buildings and Other Structures”. Reston, VA:ASCE.
American Society of Civil Engineers. (2025). “ASCE Hazard Tool.” Accessed May 2025 at:
https://ascehazardtool.org/
Bryant, W.A. and E.W. Hart. (2007). “Fault-Rupture Hazard Zones in California, Alquist-Priolo Earthquake Fault Zoning Act (with Index to Earthquake Fault Zones Maps): California Division of Mines and Geology Special Publication 42”. NR:California Department of Conservation, California Geological Survey.
Exp. 5/30/27
Jacobs
Geotechnical Investigation Data Report – Fortuna WWTP, 180 Dinsmore Drive, Fortuna, CA July 18, 2025
\\eureka\projects\2020\020143-FortunaNPDES\210-Geotech\PUBS\rpts\20250718-GeotechDataRpt-WWTP.docx California Building Standards Commission. (2022). “2022 California Building Code: California Code of Regulations, Title 24, Part 2, Volume 2 of 2, based on the 2021 International Building Code”.
Sacramento, CA: CBSC.
California Division of Mines and Geology (CDMG). (1985). “Geology and Geomorphic Features Related Landsliding, Fortuna 7.5-minute Quadrangle, Humboldt County California.” DMG Open-File Report 85-1, compiled by Richard Kilbourne. Sacramento, CA:CDMG. ---. (1991). “State of California Special Studies Zones, Fortuna Quadrangle, Humboldt County California.” Sacramento, CA:CDMG.
California Division of Mines and Geology/United States Geological Survey. (1996). “Probabilistic Seismic Hazard Assessment for the State of California.” DMG Open-File Report 96-08, USGS Open-File Report 96-706. Sacramento, CA:CDMG.
California Geological Survey.. (2002). “GIS files of Official Maps of Alquist-Priolo Earthquake Fault Zones, Northern and Eastern Region.” Sacramento, CA:CGS.
Dengler, L., R. McPherson, and G.A. Carver. (1992). “Historic Seismicity and Potential Source Areas of Large Earthquakes in North Coast California,” in Burke, R.M. and Carver, G.A. (editors), Guidebook for the 1992 Friends of the Pleistocene Field Trip, Pacific Cell. NR:NR.
Ogle, B. A. (1953). “Geology of the Eel River Valley Area, Humboldt County, California,” California Department of Natural Resources, Division of Mines, Bulletin 164. Sacramento, CA:CDMG.
Personius, S.F. and A.R. Nelson, compilers. (2005). “Fault Number 781, Cascadia Subduction Zone” in Quaternary Fault and Fold Database of the United States: U.S. Geological Survey website.
NR:USGS. Accessed May 2019 at: http://earthquakes.usgs.gov/hazards/qfaults Cone Penetration Testing
(CPT) Report 1
CONE PENETRATION TESTING
(CPT) REPORT
Gregg Drilling LLC
Prepared by: Eleni Pateras
[email protected]
Prepared for: SHN
Project D2259020
April 9, 2025
1 Table of Contents
Cone Penetration Testing (CPT) Procedure .................................................................................................. 3 15cm2 Standard Cone Specifications ............................................................................................................ 4 Cone Penetration Test Data & Interpretation .............................................................................................. 5 Pore Pressure Dissipation Tests (PPDTs)....................................................................................................... 6 Seismic Cone Penetration Tests (SCPT) ........................................................................................................ 7 Soil Sampling................................................................................................................................................. 8 Ground Water Sampling ............................................................................................................................... 9 References .................................................................................................................................................. 10 Table 1: Cone Penetration Testing Summary ............................................................................................. 11 APPENDIX A: Cone Penetration Test Plots
APPENDIX B: Pore Pressure Dissipation Test Plots
APPENDIX C: Seismic Plots & Tables
2 April 9, 2025
SHN
Attn: Giovanni Vadurro
Subject: CPT Site Investigation
Fortuna WWTP
Fortuna, CA
GREGG Project Number: D2259020
Dear Giovanni:
The following report presents the results of Gregg Drilling’s Cone Penetration Test investigation for the above referenced site. The following testing services were performed:
1 Cone Penetration Tests (CPTU)
2 Pore Pressure Dissipation Tests (PPD)
3 Seismic Cone Penetration Tests (SCPTU)
4 Groundwater Samples (GWS)
5 Soil Samples (SS)
6 Vapor Samples (VS)
A list of reference papers providing additional background on the specific tests conducted is provided in the bibliography following the text of the report. If you would like a copy of any of these publications or should you have any questions or comments regarding the contents of this report, please do not hesitate to email me at [email protected].
Sincerely,
CPT Reports Team
Gregg Drilling, LLC.
3 Cone Penetration Testing (CPT) Procedure
Gregg Drilling carries out all Cone Penetration Tests
(CPT) using an integrated electronic cone system, Figure CPT.
The cone takes measurements of tip resistance (qc),
sleeve resistance (fs), and penetration pore water
pressure (u2). Measurements are taken at either 2.5 or
5cm intervals during penetration to provide a nearly
continuous profile. CPT data reduction and basic
interpretation is performed in real time facilitating onsite decision making. The above-mentioned parameters are stored electronically for further analysis and reference. All CPT soundings are performed in
accordance with revised ASTM standards (D 5778-12).
The 5mm thick porous plastic filter element is located
directly behind the cone tip in the u2 location. A new
saturated filter element is used on each sounding to
measure both penetration pore pressures as well as
measurements during a dissipation test (PPDT). Prior to each test, the filter element is fully saturated with oil under vacuum pressure to improve accuracy.
When the sounding is completed, the test hole is
backfilled according to client specifications. If grouting is used, the procedure generally consists of pushing a
hollow tremie pipe with a “knock out” plug to the
termination depth of the CPT hole. Grout is then
pumped under pressure as the tremie pipe is pulled
from the hole. Disruption or further contamination
to the site is therefore minimized.
Figure CPT
4 15cm2 Standard Cone Specifications
Dimensions
Cone base area 15 cm2
Sleeve surface area 225 cm2
Cone net area ratio 0.75
Specifications
Cone load cell
Full scale range 180 kN (20 tons)
Overload capacity 150%
Full scale tip stress 120 MPa (1,200 tsf)
Repeatability 120 kPa (1.2 tsf)
Sleeve load cell
Full scale range 31 kN (3.5 tons)
Overload capacity 150%
Full scale sleeve stress 1,400 kPa (15 tsf)
Repeatability 1.4 kPa (0.015 tsf)
Pore pressure transducer
Full scale range 7,000 kPa (1,000 psi)
Overload capacity 150%
Repeatability 7 kPa (1 psi)
Note: The repeatability during field use will depend somewhat on ground conditions, abrasion, maintenance and zero load stability.
5 Cone Penetration Test Data & Interpretation
The Cone Penetration Test (CPT) data collected are presented in graphical and electronic form in the report. The plots include interpreted Soil Behavior Type (SBT) based on the charts described by Robertson (2010) (Figure SBT). Typical plots display SBT based on the non-normalized charts of Robertson (2010) or normalized data (2009 and 2016). For CPT soundings deeper than 30m, we recommend the use of the normalized charts of Robertson (2009 and 2016) which can be displayed as SBTn. The report also includes spreadsheet output of computer calculations of basic interpretation in terms of SBT and SBTn and various geotechnical parameters using current published correlations based on the comprehensive review by Lunne, Robertson and Powell (1997), as well as recent updates by Robertson and Cabal (Guide to Cone Penetration Testing 7th Edition, 2022). The interpretations are presented only as a guide for geotechnical use and should be carefully reviewed. Gregg Drilling LLC does not warranty the correctness or the applicability of any of the geotechnical parameters interpreted by the software and does not assume any liability for use of the results in any design or review. The user should be fully aware of the techniques and limitations of any method used in the software. Some interpretation methods require input of the groundwater level to calculate vertical effective stress. An estimate of the in-situ groundwater level has been made based on field observations and/or
CPT results but should be verified by the user.
A summary of locations and depths is available
in Table 1. Note that all penetration depths
referenced in the data are with respect to the
existing ground surface.
Note that it is not always possible to clearly
identify a soil type based solely on qt, fs, and u2.
In these situations, experience, judgment, and
an assessment of the pore pressure dissipation
data should be used to infer the correct soil
behavior type.
Figure SBT (After Robertson 2010) – Note: Colors may vary slightly compared to plots 6 Pore Pressure Dissipation Tests (PPDTs)
Pore Pressure Dissipation Tests (PPDT’s) conducted at various intervals can be used to measure equilibrium water pressure (at the time of the CPT). If conditions are hydrostatic, the equilibrium water pressure can be used to determine the approximate depth of the ground water table. A PPDT is conducted when penetration is halted at specific intervals determined by the field representative. The variation of the penetration pore pressure (u) with time is measured behind the tip of the cone and recorded.
Pore pressure dissipation data can be
interpreted to provide estimates of:
• Equilibrium piezometric pressure
• Phreatic Surface
• In situ horizontal coefficient of
consolidation (ch)
• In situ horizontal coefficient of
permeability (kh)
To correctly interpret the equilibrium
piezometric pressure and/or the phreatic
surface, the pore pressure must be
monitored until it reaches equilibrium, Figure
PPDT. This time is commonly referred to as
t100, the point at which 100% of the excess
pore pressure has dissipated.
A complete reference on pore pressure
dissipation tests is presented by Robertson et
al. 1992 and Lunne et al. 1997.
A summary of the pore pressure dissipation
tests completed for this project is included in
Table 1.
Figure PPDT
7 Seismic Cone Penetration Tests (SCPT)
Seismic Cone Penetration Testing (SCPT) can be conducted at various intervals during the Cone Penetration Test. Shear wave velocity (Vs) can then be calculated over a specified interval with depth. A small interval forseismic testing, such as 1-1.5m (3-5ft) allows for a detailed look at the shear wave profile with depth. Conversely, a larger interval such as 3-6m (10-20ft) allows for a more average shear wave velocity to be calculated. Gregg Drilling’s cones have a horizontally active geophone located 0.2m (0.66ft) behind the tip.
To conduct the seismic shear wave test, the penetration of the cone is stopped and the rods are decoupled from the rig. An automatic hammer is triggered to send a shear wave into the soil. The distance from the source to the cone is calculated knowing the total depth of the cone and the horizontal offset distance between the source and the cone. To calculate an interval velocity, a minimum of two tests must be performed at two different
depths. The arrival times
between the two wave traces
are compared to obtain the
difference in time (∆t). The
difference in depth is
calculated (∆d) and velocity
can be determined using the
simple equation: v = ∆d/∆t
Multiple wave traces can be
recorded at the same depth to
improve quality of the data.
A complete reference on
seismic cone penetration tests
is presented by Robertson et
al. 1986 and Lunne et al. 1997.
A summary of the shear wave
velocities, arrival times and
wave traces are provided with
the report.
(S)
1 2
t 1
2 1 2
12 12
Figure SCPT
8 Soil Sampling
Gregg Drilling uses a piston-type push-in sampler
to obtain small soil samples without generating
any soil cuttings, Figure SS. Two different types of
samplers (12 and 18 inch) are used depending on
the soil type and density. The soil sampler is
initially pushed in a "closed" position to the
desired sampling interval using the CPT pushing
equipment. Keeping the sampler closed
minimizes the potential of cross contamination.
The inner tip of the sampler is then retracted
leaving a hollow soil sampler with inner 1¼”
diameter sample tubes. The hollow sampler is
then pushed in a locked "open" position to collect
a soil sample. The filled sampler and push rods
are then retrieved to the ground surface. Because
the soil enters the sampler at a constant rate, the
opportunity for 100% recovery is increased. For
environmental analysis, the soil sample tube ends
are sealed with Teflon and plastic caps. Often, a
longer "split tube" can be used for geotechnical
sampling.
For a detailed reference on direct push soil
sampling, refer to Robertson et al, 1998.
Figure SS
9 Ground Water Sampling
Gregg Drilling conducts groundwater sampling using
a sampler as shown in Figure GWS. The groundwater
sampler has a retrievable stainless steel or disposable PVC screen with steel drop off tip. This allows for
samples to be taken at multiple depth intervals
within the same sounding location. In areas of slower
water recharge, provisions may be made to set
temporary PVC well screens during sampling to allow
the pushing equipment to advance to the next
sample location while the groundwater is allowed to
infiltrate.
The groundwater sampler operates by advancing
44.5mm (1¾ inch) hollow push rods with the filter tip
in a closed configuration to the base of the desired
sampling interval. Once at the desired sample depth,
the push rods are retracted; exposing the encased
filter screen and allowing groundwater to infiltrate
hydrostatically from the formation into the inlet
screen. A small diameter bailer (approximately ½ or
¾ inch) is lowered through the push rods into the
screen section for sample collection. The number of
downhole trips with the bailer and time necessary to
complete the sample collection at each depth
interval is a function of sampling protocols, volume
requirements, and the yield characteristics and
storage capacity of the formation. Upon completion
of sample collection, the push rods and sampler, with
the exception of the PVC screen and steel drop off tip
are retrieved to the ground surface, decontaminated
and prepared for the next sampling event.
For a detailed reference on direct push groundwater
sampling, refer to Zemo et. al., 1992.
Figure GWS
10 References
Lunne, T., Robertson, P.K. and Powell, J.J.M., “Cone Penetration Testing in Geotechnical Practice” E & FN Spon. ISBN 0 419 23750, 1997
Roberston, P.K., “Soil Classification using the Cone Penetration Test”, Canadian Geotechnical Journal, Vol. 27, 1990 pp. 151-158.
Robertson, P.K., 2009. Interpretation of Cone Penetration Tests – a unified approach. Canadian Geotechnical Journal, Volume 46: 1337-1355
Robertson, P.K., 2010, “Soil Behavior type from the CPT: an update”, 2nd International Symposium on Cone Penetration Testing, Huntington Beach, CA, Vol.2. pp 575-583 Robertson, P.K., 2016. “CPT-based Soil Behaviour Type (SBT) Classification System – an update”.
Canadian Geotechnical Journal, 53(12); pp 1910-1927
Robertson, P.K. and Cabal, K.L., “Guide to Cone Penetration Testing for Geotechnical Engineering”, 6th Edition, 2015, 145 p. Free online, http://www.greggdrilling.com/technical-guides.
Mayne, P.W., “NHI (2002) Manual on Subsurface Investigations: Geotechnical Site Characterization”, available through www.ce.gatech.edu/~geosys/Faculty/Mayne/papers/index.html, Section 5.3, pp. 107- 112.
Robertson, P.K., R.G. Campanella, D. Gillespie and A. Rice, “Seismic CPT to Measure In-Situ Shear Wave Velocity”, Journal of Geotechnical Engineering ASCE, Vol. 112, No. 8, 1986 pp. 791-803.
Robertson, P.K., Sully, J., Woeller, D.J., Lunne, T., Powell, J.J.M., and Gillespie, D.J., "Guidelines for Estimating Consolidation Parameters in Soils from Piezocone Tests", Canadian Geotechnical Journal, Vol. 29, No. 4, August 1992, pp. 539-550.
Robertson, P.K., T. Lunne and J.J.M. Powell, “Geo-Environmental Application of Penetration Testing”, Geotechnical Site Characterization, Robertson & Mayne (editors), 1998 Balkema, Rotterdam, ISBN 90 5410 939 4 pp 35-47.
Copies of ASTM Standards are available through www.astm.org 11 Table 1: Cone Penetration Testing Summary
CPT Sounding
Identification
Date Termination
Depth (ft)
Depth of
Soil
Samples
(ft)
Depth of
Groundwater
Samples (ft)
Depth of Pore
Pressure
Dissipation Tests
(ft)
CPT-25-01 4/7/2025 50.00 - - 25.00, 50.00
CPT-25-02 4/7/2025 36.02 - - 19.75, 36.02
SCPT-25-03 4/8/2025 38.12 - - 9.97, 30.45
APPENDIX A:
CPT PLOTS
CLIENT: SHN
GREGG DRILLING, LLChttps://www.greggdrilling.com/
FORTUNA WWTP, FORTUNA, CA Total depth: 50.00 ft, Date: 4/07/2025 CPT: CPT-25-01
SITE:
FIELD REP: GIOVANNI V
Cone ID: 2501023
Cone resistance qt
HAND AUGER
Tip resistance (tsf)
0 100 200 300 400 500 600
Depth (ft)
6058565452504846444240383634323028262422201816141210
86420
Cone resistance qt Sleeve friction
HAND AUGER
Friction (tsf)
0 2 4 6 8 10
Depth (ft)
6058565452504846444240383634323028262422201816141210
86420
Sleeve friction Friction ratio
HAND AUGER
Rf (%)
0 2 4 6 8 10
Depth (ft)
6058565452504846444240383634323028262422201816141210
86420
Friction ratio SPT N60
HAND AUGER
N60 (blows/ft)
0 20 40 60 80 100
Depth (ft)
6058565452504846444240383634323028262422201816141210
86420
SPT N60 Soil Behaviour Type
HAND AUGER
SBT (Robertson, 2010)
0 2 4 6 8 10 12 14 16 18
Depth (ft)
6058565452504846444240383634323028262422201816141210
86420
Soil Behaviour Type
ClayClay & silty clayClayClay & silty clayClayClay & silty clayClay & silty claySilty sand & sandy siltClay & silty claySilty sand & sandy siltSilty sand & sandy siltClayClay & silty clayClayClay & silty claySand & silty sandSandSandSand & silty sandSand & silty sandSand & silty sandSand & silty sand CPeT-IT v.20.0.2.33 - CPTU data presentation & interpretation software - Report created on: 4/9/2025, 2:27:26 PM 1Project file: C:\Users\EPateras\OneDrive - Sealaska Corporation\Desktop\9020BN\Report\259020BN.cpt CLIENT: SHN
GREGG DRILLING, LLChttps://www.greggdrilling.com/
FORTUNA WWTP, FORTUNA, CA Total depth: 50.00 ft, Date: 4/07/2025 CPT: CPT-25-01
SITE:
FIELD REP: GIOVANNI V
Cone ID: 2501023
Cone resistance qt
HAND AUGER
Tip resistance (tsf)
0 100 200 300 400 500 600
Depth (ft)
6058565452504846444240383634323028262422201816141210
86420
Cone resistance qt Sleeve friction
HAND AUGER
Friction (tsf)
0 2 4 6 8 10
Depth (ft)
6058565452504846444240383634323028262422201816141210
86420
Sleeve friction Friction ratio
HAND AUGER
Rf (%)
0 2 4 6 8 10
Depth (ft)
6058565452504846444240383634323028262422201816141210
86420
Friction ratio Pore pressure u
HAND AUGER
Pressure (psi)
0 50 100
Depth (ft)
6058565452504846444240383634323028262422201816141210
86420
Pore pressure u
Diss.
Diss.
Soil Behaviour Type
HAND AUGER
SBT (Robertson, 2010)
0 2 4 6 8 10 12 14 16 18
Depth (ft)
6058565452504846444240383634323028262422201816141210
86420
Soil Behaviour Type
ClayClay & silty clayClayClay & silty clayClayClay & silty clayClay & silty claySilty sand & sandy siltClay & silty claySilty sand & sandy siltSilty sand & sandy siltClayClay & silty clayClayClay & silty claySand & silty sandSandSandSand & silty sandSand & silty sandSand & silty sandSand & silty sand CPeT-IT v.20.0.2.33 - CPTU data presentation & interpretation software - Report created on: 4/9/2025, 2:27:26 PM 2Project file: C:\Users\EPateras\OneDrive - Sealaska Corporation\Desktop\9020BN\Report\259020BN.cpt CLIENT: SHN
GREGG DRILLING, LLChttps://www.greggdrilling.com/
FORTUNA WWTP, FORTUNA, CA Total depth: 36.02 ft, Date: 4/07/2025 CPT: CPT-25-02
SITE:
FIELD REP: GIOVANNI V
Cone ID: 2501023
Cone resistance qt
HAND AUGER
Tip resistance (tsf)
0 100 200 300 400 500 600
Depth (ft)
6058565452504846444240383634323028262422201816141210
86420
Cone resistance qt Sleeve friction
HAND AUGER
Friction (tsf)
0 2 4 6 8 10
Depth (ft)
6058565452504846444240383634323028262422201816141210
86420
Sleeve friction Friction ratio
HAND AUGER
Rf (%)
0 2 4 6 8 10
Depth (ft)
6058565452504846444240383634323028262422201816141210
86420
Friction ratio SPT N60
HAND AUGER
N60 (blows/ft)
0 20 40 60 80 100
Depth (ft)
6058565452504846444240383634323028262422201816141210
86420
SPT N60 Soil Behaviour Type
HAND AUGER
SBT (Robertson, 2010)
0 2 4 6 8 10 12 14 16 18
Depth (ft)
6058565452504846444240383634323028262422201816141210
86420
Soil Behaviour Type
ClayClay & silty clayClay & silty claySand & silty sandSilty sand & sandy siltClay & silty claySilty sand & sandy siltClayClay & silty clayClaySand & silty sandSilty sand & sandy silt CPeT-IT v.20.0.2.33 - CPTU data presentation & interpretation software - Report created on: 4/9/2025, 2:27:26 PM 3Project file: C:\Users\EPateras\OneDrive - Sealaska Corporation\Desktop\9020BN\Report\259020BN.cpt CLIENT: SHN
GREGG DRILLING, LLChttps://www.greggdrilling.com/
FORTUNA WWTP, FORTUNA, CA Total depth: 36.02 ft, Date: 4/07/2025 CPT: CPT-25-02
SITE:
FIELD REP: GIOVANNI V
Cone ID: 2501023
Cone resistance qt
HAND AUGER
Tip resistance (tsf)
0 100 200 300 400 500 600
Depth (ft)
6058565452504846444240383634323028262422201816141210
86420
Cone resistance qt Sleeve friction
HAND AUGER
Friction (tsf)
0 2 4 6 8 10
Depth (ft)
6058565452504846444240383634323028262422201816141210
86420
Sleeve friction Friction ratio
HAND AUGER
Rf (%)
0 2 4 6 8 10
Depth (ft)
6058565452504846444240383634323028262422201816141210
86420
Friction ratio Pore pressure u
HAND AUGER
Pressure (psi)
0 50 100
Depth (ft)
6058565452504846444240383634323028262422201816141210
86420
Pore pressure u
Diss.
Diss.
Soil Behaviour Type
HAND AUGER
SBT (Robertson, 2010)
0 2 4 6 8 10 12 14 16 18
Depth (ft)
6058565452504846444240383634323028262422201816141210
86420
Soil Behaviour Type
ClayClay & silty clayClay & silty claySand & silty sandSilty sand & sandy siltClay & silty claySilty sand & sandy siltClayClay & silty clayClaySand & silty sandSilty sand & sandy silt CPeT-IT v.20.0.2.33 - CPTU data presentation & interpretation software - Report created on: 4/9/2025, 2:27:26 PM 4Project file: C:\Users\EPateras\OneDrive - Sealaska Corporation\Desktop\9020BN\Report\259020BN.cpt CLIENT: SHN
GREGG DRILLING, LLChttps://www.greggdrilling.com/
FORTUNA WWTP, FORTUNA, CA Total depth: 38.12 ft, Date: 4/08/2025 CPT: SCPT-25-03
SITE:
FIELD REP: GIOVANNI V
Cone ID: 2501023
Cone resistance qt
HAND AUGER
Tip resistance (tsf)
0 100 200 300 400 500 600
Depth (ft)
6058565452504846444240383634323028262422201816141210
86420
Cone resistance qt Sleeve friction
HAND AUGER
Friction (tsf)
0 2 4 6 8 10
Depth (ft)
6058565452504846444240383634323028262422201816141210
86420
Sleeve friction Friction ratio
HAND AUGER
Rf (%)
0 2 4 6 8 10
Depth (ft)
6058565452504846444240383634323028262422201816141210
86420
Friction ratio SPT N60
HAND AUGER
N60 (blows/ft)
0 20 40 60 80 100
Depth (ft)
6058565452504846444240383634323028262422201816141210
86420
SPT N60 Soil Behaviour Type
HAND AUGER
SBT (Robertson, 2010)
0 2 4 6 8 10 12 14 16 18
Depth (ft)
6058565452504846444240383634323028262422201816141210
86420
Soil Behaviour Type
ClayClay & silty clayClay & silty clayClay & silty clayClayClayClay & silty clayClayClay & silty claySilty sand & sandy siltSand & silty sandSilty sand & sandy siltSand & silty sandSand & silty sandSand CPeT-IT v.20.0.2.33 - CPTU data presentation & interpretation software - Report created on: 4/9/2025, 2:27:26 PM 5Project file: C:\Users\EPateras\OneDrive - Sealaska Corporation\Desktop\9020BN\Report\259020BN.cpt CLIENT: SHN
GREGG DRILLING, LLChttps://www.greggdrilling.com/
FORTUNA WWTP, FORTUNA, CA Total depth: 38.12 ft, Date: 4/08/2025 CPT: SCPT-25-03
SITE:
FIELD REP: GIOVANNI V
Cone ID: 2501023
Cone resistance qt
HAND AUGER
Tip resistance (tsf)
0 100 200 300 400 500 600
Depth (ft)
6058565452504846444240383634323028262422201816141210
86420
Cone resistance qt Sleeve friction
HAND AUGER
Friction (tsf)
0 2 4 6 8 10
Depth (ft)
6058565452504846444240383634323028262422201816141210
86420
Sleeve friction Friction ratio
HAND AUGER
Rf (%)
0 2 4 6 8 10
Depth (ft)
6058565452504846444240383634323028262422201816141210
86420
Friction ratio Pore pressure u
HAND AUGER
Pressure (psi)
0 50 100
Depth (ft)
6058565452504846444240383634323028262422201816141210
86420
Pore pressure u
Diss.
Diss.
Soil Behaviour Type
HAND AUGER
SBT (Robertson, 2010)
0 2 4 6 8 10 12 14 16 18
Depth (ft)
6058565452504846444240383634323028262422201816141210
86420
Soil Behaviour Type
ClayClay & silty clayClay & silty clayClay & silty clayClayClayClay & silty clayClayClay & silty claySilty sand & sandy siltSand & silty sandSilty sand & sandy siltSand & silty sandSand & silty sandSand CPeT-IT v.20.0.2.33 - CPTU data presentation & interpretation software - Report created on: 4/9/2025, 2:27:26 PM 6Project file: C:\Users\EPateras\OneDrive - Sealaska Corporation\Desktop\9020BN\Report\259020BN.cpt CLIENT: SHN
GREGG DRILLING, LLChttps://www.greggdrilling.com/
FORTUNA WWTP, FORTUNA, CA Total depth: 38.12 ft, Date: 4/08/2025 CPT: SCPT-25-03
SITE:
FIELD REP: GIOVANNI V
Cone ID: 2501023
SBTn legend
1. Sensitive fine grained2. Organic material3. Clay to silty clay
4. Clayey silt to silty clay5. Silty sand to sandy silt6. Clean sand to silty sand
7. Gravelly sand to sand8. Very stiff sand to clayey sand9. Very stiff fine grained Cone resistance qt
HAND AUGER
Tip resistance (tsf)
0 100 200 300 400 500 600
Depth (ft)
6058565452504846444240383634323028262422201816141210
86420
Cone resistance qt Sleeve friction
HAND AUGER
Friction (tsf)
0 2 4 6 8 10
Depth (ft)
6058565452504846444240383634323028262422201816141210
86420
Sleeve friction Friction ratio
HAND AUGER
Rf (%)
0 2 4 6 8 10
Depth (ft)
6058565452504846444240383634323028262422201816141210
86420
Friction ratio Shear Wave velocity
HAND AUGER
Vs (ft/s)
0 500 1 ,0 0 0 1 ,5 0 0 2 ,0 0 0
Depth (ft)
6058565452504846444240383634323028262422201816141210
86420
Measured V s
Shear Wave velocity Soil Behaviour Type
HAND AUGER
SBT (Robertson, 2010)
0 2 4 6 8 10 12 14 16 18
Depth (ft)
6058565452504846444240383634323028262422201816141210
86420
Soil Behaviour Type
ClayClay & silty clayClay & silty clayClay & silty clayClayClayClay & silty clayClayClay & silty claySand & silty sandSilty sand & sandy siltSand & silty sandSand & silty sandSand CPeT-IT v.20.0.2.33 - CPTU data presentation & interpretation software - Report created on: 4/9/2025, 2:27:49 PM 1Project file: C:\Users\EPateras\OneDrive - Sealaska Corporation\Desktop\9020BN\Report\259020BN.cpt APPENDIX B:
PORE PRESSURE DISSIPATION
TEST PLOTS
This software is licensed to: Gregg Drilling Inc. CPT name: CPT-25-01 Piezocone Dissipation Test: CPT-25-01
Depth: 25.00 (ft)
t (s)
0 500 1,000 1,500
Porepressure u2 (psi)
10 9.5
9 8.5
8 7.5
7 6.5
6 5.5
5 4.5
4 3.5
3 2.5
2 1.5
1 0.5
0 Piezocone Dissipation Test: CPT-25-01
Depth: 25.00 (ft)
u0 = 8.06 (psi)
Pore pressure
Pressure (psi)
0 20 40 60 80 100
Depth (ft)
60 58
56 54
52 50
48 46
44 42
40 38
36 34
32 30
28 26
24 22
20 18
16 14
12 10
8 6
4 2
0 u2 penetration
Initial dissipation
End of dissipation (extrapolated)
Initial estimated at t=0
Pore pressure
1 Project file: C:\Users\EPateras\OneDrive - Sealaska Corporation\Desktop\9020BN\Report\259020BN.cpt CPeT-IT v.20.0.2.33 - CPTU data presentation & interpretation software - Report created on: 4/9/2025, 2:15:44 PM This software is licensed to: Gregg Drilling Inc. CPT name: CPT-25-01 Piezocone Dissipation Test: CPT-25-01
Depth: 50.00 (ft)
t (s)
0 500 1,000 1,500
Porepressure u2 (psi)
15 14
13 12
11 10
9 8
7 6
5 4
3 2
1 0
-1
-2
-3
-4
-5
-6
-7
-8
-9
-10
Piezocone Dissipation Test: CPT-25-01
Depth: 50.00 (ft)
u0 = 11.39 (psi)
Pore pressure
Pressure (psi)
0 20 40 60 80 100
Depth (ft)
60 58
56 54
52 50
48 46
44 42
40 38
36 34
32 30
28 26
24 22
20 18
16 14
12 10
8 6
4 2
0 u2 penetration
Initial dissipation
End of dissipation (extrapolated)
Initial estimated at t=0
Pore pressure
2 Project file: C:\Users\EPateras\OneDrive - Sealaska Corporation\Desktop\9020BN\Report\259020BN.cpt CPeT-IT v.20.0.2.33 - CPTU data presentation & interpretation software - Report created on: 4/9/2025, 2:15:44 PM This software is licensed to: Gregg Drilling Inc. CPT name: CPT-25-02 Piezocone Dissipation Test: CPT-25-02
Depth: 19.75 (ft)
t (s)
0 100 200 300 400 500 600 700
Porepressure u2 (psi)
10 9.5
9 8.5
8 7.5
7 6.5
6 5.5
5 4.5
4 3.5
3 2.5
2 1.5
1 0.5
0 Piezocone Dissipation Test: CPT-25-02
Depth: 19.75 (ft)
u0 = 4.99 (psi)
Pore pressure
Pressure (psi)
0 20 40 60 80 100
Depth (ft)
60 58
56 54
52 50
48 46
44 42
40 38
36 34
32 30
28 26
24 22
20 18
16 14
12 10
8 6
4 2
0 u2 penetration
Initial dissipation
End of dissipation (extrapolated)
Initial estimated at t=0
Pore pressure
1 Project file: C:\Users\EPateras\OneDrive - Sealaska Corporation\Desktop\9020BN\Report\259020BN.cpt CPeT-IT v.20.0.2.33 - CPTU data presentation & interpretation software - Report created on: 4/9/2025, 2:15:16 PM This software is licensed to: Gregg Drilling Inc. CPT name: CPT-25-02 Piezocone Dissipation Test: CPT-25-02
Depth: 36.02 (ft)
t (s)
0 100 200 300 400 500 600 700 800
Porepressure u2 (psi)
10 9
8 7
6 5
4 3
2 1
0 -1
-2
-3
-4
-5
-6
-7
-8
-9
-10
Piezocone Dissipation Test: CPT-25-02
Depth: 36.02 (ft)
u0 = 5.09 (psi)
Pore pressure
Pressure (psi)
0 20 40 60 80 100
Depth (ft)
60 58
56 54
52 50
48 46
44 42
40 38
36 34
32 30
28 26
24 22
20 18
16 14
12 10
8 6
4 2
0 u2 penetration
Initial dissipation
End of dissipation (extrapolated)
Initial estimated at t=0
Pore pressure
2 Project file: C:\Users\EPateras\OneDrive - Sealaska Corporation\Desktop\9020BN\Report\259020BN.cpt CPeT-IT v.20.0.2.33 - CPTU data presentation & interpretation software - Report created on: 4/9/2025, 2:15:16 PM This software is licensed to: Gregg Drilling Inc. CPT name: SCPT-25-03 Piezocone Dissipation Test: SCPT-25-03
Depth: 9.97 (ft)
t (s)
0 200 400 600 800 1,000
Porepressure u2 (psi)
20 19
18 17
16 15
14 13
12 11
10 9
8 7
6 5
4 3
2 1
0 Piezocone Dissipation Test: SCPT-25-03
Depth: 9.97 (ft)
u0 = 12.45 (psi)
Pore pressure
Pressure (psi)
0 20 40 60 80 100
Depth (ft)
60 58
56 54
52 50
48 46
44 42
40 38
36 34
32 30
28 26
24 22
20 18
16 14
12 10
8 6
4 2
0 u2 penetration
Initial dissipation
End of dissipation (extrapolated)
Initial estimated at t=0
Pore pressure
1 Project file: C:\Users\EPateras\OneDrive - Sealaska Corporation\Desktop\9020BN\Report\259020BN.cpt CPeT-IT v.20.0.2.33 - CPTU data presentation & interpretation software - Report created on: 4/9/2025, 2:17:22 PM This software is licensed to: Gregg Drilling Inc. CPT name: SCPT-25-03 Piezocone Dissipation Test: SCPT-25-03
Depth: 30.45 (ft)
t (s)
0 200 400 600 800 1,000
Porepressure u2 (psi)
5 4.8
4.6 4.4
4.2 4
3.8 3.6
3.4 3.2
3 2.8
2.6 2.4
2.2 2
1.8 1.6
1.4 1.2
1 0.8
0.6 0.4
0.2 Piezocone Dissipation Test: SCPT-25-03
Depth: 30.45 (ft)
u0 = 1.61 (psi)
Pore pressure
Pressure (psi)
0 20 40 60 80 100
Depth (ft)
60 58
56 54
52 50
48 46
44 42
40 38
36 34
32 30
28 26
24 22
20 18
16 14
12 10
8 6
4 2
0 u2 penetration
Initial dissipation
End of dissipation (extrapolated)
Initial estimated at t=0
Pore pressure
2 Project file: C:\Users\EPateras\OneDrive - Sealaska Corporation\Desktop\9020BN\Report\259020BN.cpt CPeT-IT v.20.0.2.33 - CPTU data presentation & interpretation software - Report created on: 4/9/2025, 2:17:22 PM APPENDIX C:
SEISMIC
PLOTS & TABLES
GREGG DRILLING, LLC
WWW.GREGGDRILLING.COM
Average S signals full graph (L & R signals)
Time (ms)
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 135 140 145 150 155 160 165 170 175 180 185 190 195 2000 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 135 140 145 150 155 160 165 170 175 180 185 190 195 200 Depth (ft)
40.0039.0038.0037.0036.0035.0034.0033.0032.0031.0030.0029.0028.0027.0026.0025.0024.0023.0022.0021.0020.0019.0018.0017.0016.0015.0014.0013.0012.0011.0010.00
9.008.007.006.005.004.003.002.001.000.00
40.0039.0038.0037.0036.0035.0034.0033.0032.0031.0030.0029.0028.0027.0026.0025.0024.0023.0022.0021.0020.0019.0018.0017.0016.0015.0014.0013.0012.0011.0010.00
9.008.007.006.005.004.003.002.001.000.00
565.95 ft/s (8.60 ms)
704.08 ft/s (6.95 ms)
523.27 ft/s (9.00 ms)
675.65 ft/s (7.85 ms)
1244.66 ft/s (4.05 ms)
Average S signals full graph (L & R signals)
Project: D2259020 - SHN Borehole ID: SCPT-25-03
S.P.A.S. 2016 v.4.0.3.1 - Signal Processing and Analysis SoftwareProject file: C:\Users\EPateras\OneDrive - Sealaska Corporation\Desktop\9020BN\Seismic\259020BN SPAS.spa 1