Amendment 0002 - GEOTECH REPORT USACE MOTCO Railroad Curves Rehab.pdf

GEOTECHNICAL ENGINEERING REPORT

USACE MILITARY OCEAN TERMINAL CONCORD (MOTCO)

RAILROAD REHABILITATION PROJECT

CLYDE, CONTRA COSTCA COUNTY, CA

For

HDR Engineering, Inc.

1917 S. 67th Street Omaha, NE 68106

PARIKH CONSULTANTS, INC.

1497 N. Milpitas Boulevard

Milpitas, CA 95035

March 22nd, 2021 Job No. 2019-132-GEO

DRAFT

TABLE OF CONTENTS PAGE

1.0 INTRODUCTION

2.0 PROJECT DESCRIPTION

3.0 FIELD INVESTIGATION AND TESTING PROGRAM

4.0 LABORATORY TESTING PROGRAM

5.0 GEOLOGY, SEISMICITY AND SUBSURFACE CONDITIONS

5.1 Regional Geology

5.2 Subsurface Conditions

6.0 CORROSION EVALUATION

7.0 SEISMIC DESIGN INFORMATION AND RECOMMENDATIONS

7.1 Seismic Sources

7.2 Seismic Design Criteria

7.3 Seismic Hazards

8.0 GEOTECHNICAL DESIGN CONSIDERATIONS

9.0 GEOTECHNICAL RECOMMENDATIONS

9.1 General

9.2 Soil Index Properties and Undrained Shear Strength

9.3 Embankment Settlement Evaluation

9.4 Trackway Support and Grading

Soil Conditions at Shallow Depth Grading Subgrade Preparation Import Material Compaction Requirements Slope Ratios

9.5 Working Platform

9.6 Drainage

10.0 CONSTRUCTION OBSERVATION

11.0 INVESTIGATION LIMITATIONS

LIST OF PLATES

Plate No. 1: Project Location Map Plate No. 2: Boring Location Map Plate No. 3A: Geologic Map Plate No. 3B: Young Bay Mud Thickness Contour Plate No. 4A: Fault Map Plate No. 4B: Alquist-Priolo Map (Vinehill Quadrangle) Plate Nos. 5A to 5E: Generalized Soil Profiles and Soil Properties Plate Nos. 6A to 6D: Generalized Soil Index Properties Plate Nos. 7A to 7E: Generalized Soil Strength Data

APPENDICES

APPENDIX A: Log of Test Borings and Cone Penetration Test Results APPENDIX B: Summary of Laboratory Test Results APPENDIX C: Settlement Evaluation for Various Areas

GEOTECHNICAL ENGINEERING REPORT

CLYDE, CONTRA COSTCA COUNTY, CA

1.0 INTRODUCTION

The report provides geotechnical design information for the proposed Railroad Rehabilitation

Project in USACE Military Ocean Terminal Concord (MOTCO) in Clyde, Contra Costa County, CA.

The contract is with HDR Engineering, Inc. The approximate location of the site is shown on the

Project Location Map (Plate No. 1).

The purpose of this investigation was to evaluate the general soil and groundwater conditions at the project site, to evaluate their engineering properties, and to provide geotechnical design recommendations for the proposed railroad curves. The scope of work performed for this investigation included a review of the readily available soil and geologic literature pertaining to the site, drilling of 18 exploratory soil borings, obtaining representative soil samples and logging subsurface materials encountered in the borings, conducting 13 Cone Penetration Testing (CPT) soundings, laboratory testing of the representative soil samples, performing engineering analyses, and preparation of this report.

The geotechnical information and design criteria presented in this report are intended to characterize the subsurface conditions and provide design recommendations for the proposed project. The geotechnical recommendations presented in this report are intended for design input and are not intended to be used directly as specifications. These recommendations should not be used directly for bidding purposes by prospective contractors.

2.0 PROJECT DESCRIPTION

The Military Ocean Terminal, Concord (MOTCO) is DoD’s primary West Coast port for the movement of containerized ammunition during contingency and peacetime operations. The project is to repair the rail, ties and catwalk on the T1 Bridge and replace the rail curves with curvature less than 12 degrees per 100’ chord (total of 20 rail curves). The project will allow modern rail cars and locomotive access.

The base design project includes the work to the T1 Bridge and 14 of the 19 curves replacements.

The remaining 5 curve replacements and construction of the new curve are covered by bid options that were not included the base design scope due to additional complexity associated with the potential for wetland impacts and/or the need to interface with the Union Pacific

Railroad.

Job No. 2019-132-GEO (MOTCO) March 22nd, 2021

The new tracks will be constructed with 115-lb minimum rail on wood ties. The project also includes the necessary embankment construction, subballast, ballast and other track materials to provide a new rail alignment. Based on preliminary plans provided, the configuration of the planned new embankments will generally have the Top of Rail (TOR) near existing grade and up to approximately 2 to 4 feet above existing grade, and the embankment width is typically on the order of 20 feet, except that Curves 3, 7, 8 and 17 may have new embankment up to about 40 feet wide.

3.0 FIELD INVESTIGATION AND TESTING PROGRAM

The subsurface investigation of the site included drilling of total 18 mud-rotary borings and 13

CPT soundings. The borings extended to 30 to 50 feet depth and CPT soundings were all 50 feet in the vicinity at the proposed railroad curves. The approximate locations of the borings CPTs are presented on the Boring Location Map, Plate No. 2. The table below summarizes the boring identifications and the associated curves.

Table 3.1 Investigation Summary

Proposed Railroad Curves Exploration I.D.

Approximate Site

Location in MOTCO

Cures 13, 14, 15 & 16 CPT-1, B-2, CPT-3, B-4, CPT-5, B-6 & B-7 NW Quadrant

Curves 3, 7 & 8 B-8, CPT-9 & B-13 NW Quadrant & Middle

Curves 9, 10, 11 & 12 CPT-14, B-15, CPT-16, B-17, B-18, CPT-19 & B-20 NE Quadrant

Curves 17 & 20 B-21, B-22, CPT-23, B-24 & CPT-25 SE Quadrant

Curves 18 & 19 CPT-26, CPT-27, CPT-28 & B-29 South End

Curves 1, 2, 4, 5 & 6 B-30, B-31, B-10, B-11 & CPT-12 SW Quadrant

The rotary drilling was performed by Pitcher Drilling Company from East Palo Alto, California using a truck-mounted CME rig. The drilling at each hole began with hand-auger in 1 foot increment with Unexploded Ordnance (UXO) checks to depth of 5 feet to clear the boring locations per the approved Work Plan. The drilling then proceeded with hollow stem auger and rotary drilling when groundwater was encountered.

Drive samples of soil encountered in the borings were obtained at selected depths using either a

3.0-inch O.D. (2.5-inch I.D.) Modified California (MC) sampler lined with 1-inch brass rings, or 1.5-inch I.D. (shoe diameter 1-3/8-inch) Standard Penetration Test (SPT) sampler at various depths.

The sampling also included direct push Shelby tubes and piston sampler for clayey materials.

Drive samplers were driven into subsurface soils under the impact of a 140-pound automatic hammer having a free fall of 30 inches. The raw blow counts required to drive the particular type of sampler for the last 12 inches are presented on the boring logs. Pocket pen readings and/or

Torvane readings were performed where appropriate. The Logs of Test Borings and details regarding the samplers and other symbols used on the logs are included in Appendix A.

Hammer energy calibration information provided by Pitcher Services for the rig’s automatic hammer shows the hammer to have an efficiency of approximately 87%. Blow counts for the MC sampler may be correlated to equivalent SPT blow counts using a method suggested by Daniel, Howie, and Sy (2003), by multiplying MC blow counts by a conversion factor of 0.65.

The CPT soundings were conducted by Gregg Drilling from Martinez in accordance with revised

ASTM D5778. During the operation, the instrumented cone was hydraulically pushed into the ground, and readings (tip resistance, frictional resistance, and water pressure) were recorded digitally. Pore pressure dissipation Tests were also performed at selected depths.

The drilling operation was conducted by our Field Geologist who maintained logs of the materials encountered in the borings, recovered, and prepared the soil samples for transport. Samples recovered from the borings were transported to our laboratory for further evaluation and testing.

Following the drilling, the boreholes were backfilled with cement grout using tremie method.

Borehole abandonment was inspected by Contra Costa County Health Department per permit requirements.

Drilling spoils generated during the drilling process were removed from the site daily. Drill spoils were picked-up by Pitcher Services’ subcontractor, Integrated Waste Management (IWM) and transported to their licensed waste facility for holding pending the results of analytical testing on the soil cuttings and were subsequently disposed by IWM.

4.0 LABORATORY TESTING PROGRAM

Laboratory tests were performed on selected soil samples to evaluate the physical and engineering properties of soils. The test types performed for this study included:

• Moisture Content (ASTM D 2216)

• Atterberg Limits (ASTM D 4318)

• Particle Size Analyses (PA) (ASTM D 422)

• Triaxial Unconsolidated Undrained (UU) Test (ASTM D 2850)

• Consolidation (ASTM D 2435)

• R-value (ASTM D2844)

• Corrosion (California Test Methods 643/417/422)

The Triaxial UU tests and some consolidation tests were performed by Cooper Testing Laboratory in Palo Alto, California. The corrosion tests were performed by Sunland Analytical in Rancho

Cordova, California. The laboratory test results are presented in Appendix B.

5.0 GEOLOGY, SEISMICITY AND SUBSURFACE CONDITIONS

5.1 Regional Geology

MOTCO is located within the geologically complex Coast Ranges Geomorphic province on the southern edge of Suisun Bay. Plate No. 3A shows the distribution of geological units at the site and is derived from “Maps of Quaternary Deposits and Liquefaction Susceptibility in the Central San Francisco Bay Region, California, USGS OF-06-1037” (Witter et. al, 2006).

The site is covered by a thick layer of unconsolidated sediments over bedrock. Topography of the greater Project area suggests depth to bedrock is likely greater than several hundred feet.

The two geological units of note are the presence of Bay Mud and artificial fill. Bay Mud in the vicinity of the Project probably consists of soft clays, silts and peat with occasional sandy lenses. Thickness of Bay mud at the site is likely be thickest at the margin of Suisun Bay thinning toward the south. We referred to Special Report 97, Geologic and Engineering

Aspects of San Francisco Bay Fill, published by California Division Mines and Geology (1969).

An excerpt of the contour map for thickness of Young Bay Mud of the area is presented in

Plate No. 3B. Based on the information, the Young Bay Mud thickness may be up to 40 feet at north end by the Suisun Bay and minimal at south end.

An 1886 survey map of Suisun Bay map shows the majority of the site was tide marsh which was presumably at or near sea level. Fill appears to have been emplaced over the native soils to construct levees, railroads, roads, embankments, and revetments. Artificial fill (af) appears to have placed over the area that corresponds to “upland” on the 1886 map. No part of the proposed works appears to be directly underlain by Bay Mud (Qhbm), however significant portions of the proposed works are constructed on artificial fill placed over Bay

Mud (afem). Areas where fill was placed over Bay Mud should have been susceptible to general areal settlement.

The composition of fill (af and afem) across the MOTCO site has previously been described as consisting of varying proportions of clay, silt, sand, and gravel (Tetra Tech, 2008). The north-west area of the site in the vicinity of curves 13 to 16 has a long history of industrial use dating from the late 1800’s including a copper smelter, shipbuilding yard, and a ship breaking yard. Debris and other industrial materials could have been incorporated into and/or underlie fill.

The Los Medanos – Roe Island thrust fault is mapped to run through the Project site (Plate

No. 4). The location of the fault as shown is derived from Caltrans Fault Database V2a, 2012, the spatial resolution of which is relatively coarse. The specific location of the fault should not be drawn from this data. The fault is also referred to as the Los Medanos Thrust and is described by Weber-Band et al (1997) as being an active compression-related structure.

The Concord fault strikes north-west and is located approximately 3.0 miles south-west of the Project area and probably connects with the north-west striking Green Valley fault across Suisun Bay. Both faults are considered to be active and are shown on Plate No. 4.

5.2 Subsurface Conditions

Based on the general locations of the proposed railroad curves, four soil profiles are provided (Plate Nos. 5B thru 5E). The soil profiles are generalized from relevant rotary borings and CPT soundings in the area. The existing grade in MOTCO appears to be approximately in the range of Elev. 8 to 12 feet. The upper part of the soil crust consists of man-placed fills that are typically stiff lean to fat clays and sand to silty sand. The four generalized soil profiles are labelled in Plate No. 5A and are as follows:

• Section A-A’: Curves 3, 13, 14, 15 & 16 (NW Quadrant of the site)

• Section B-B’: Curves 9, 10, 11 & 12 (NE Quadrant of the site)

• Section C-C’: Curves 17 & 20 (SE Quadrant of the site)

• Section D-D’: Curves 1, 2, 4, 5, 6, 18 & 19 (SW Quadrant and South End of the site)

Section A-A’. The subsoils encountered generally consist of stiff to very stiff fine-grained clays and silts with some sporadic sand lenses. The natural moisture contents of the soils are in the range of 25% to 30% that is normal for lean to fat clays in the area. The borings and CPT soundings in this area did not indicate Young Bay Mud.

Curves 7 and 8 are located in the middle part of the site. Boring B-13 was drilled at the location and did not encounter soft Young Bay Mud. The subsoils indicated in B-13 appear to be similar to that of Section A-A’, stiff to very stiff fine-grained soils with medium dense sand layers.

Section B-B’. The section is along the north land margin by the Suisun Bay. The explorations encountered some medium stiff to stiff clays overlying peat and organic soil through about Elev. -25 feet. The peat and organic soils appear to be soft to medium stiff in consistency per the CPT soundings and strength tests, but the materials contain very high moisture contents, up to 240% to 340%. The soils below the peat/organic materials are typically very stiff to hard fine-grained clays and silts with moisture contents in the range of 20% to 30%. Dense sands were also encountered in the boring data.

Section C-C’. The section is in the SE quadrant of the site for Curves 17 & 20. The boring and CPT data encountered generally stiff to very stiff fine-grained clays and silt with some sand lenses, except that locally (Boring B-24) encountered very soft organic soils at about

Elev. -4 feet to -10.5 feet. The natural moisture content of the organic soil is 93%. It appears that B-24 encountered granular fill over an old low lying marsh land.

Section D-D’. The section goes from the north end of T1 bridge (SW Quadrant of the site) to the south end near Curve 19 by Waterfront Road. Near the north end of T1 bridge, Borings B-31, B-10 and B-11 indicated organic soils in soft to medium stiff consistency with moisture contents ranging from 62% to 276%. The organic soils extend from about Elev. 0 to Elev. -12 feet and to -38 feet. Going further south along the section, the soils generally consist of stiff to very stiff fine-grained clays and silts, and only minor organic soils were encountered (CPT-12, 26, 28 and B-29).

Groundwater. Groundwater was typically measured encountered at 5 to 10 feet depth below existing ground surface. The existing ground surface generally ranges from Elev. 8 to 12 feet, and the natural groundwater level is associated with tidal water in the Bay. It is reasonable to assume groundwater at about Elev. 5 feet for project design.

Groundwater elevation could significantly vary in the event of a ‘normal’ rainfall period or following an El Nino event. Also, groundwater may take time to recharge or react to such changes as seasonal fluctuations, tidal changes, or the extreme conditions as noted above, and such changes may or may not affect the groundwater immediately following such event. Therefore, it is all-the-more important to not rely on such transient measurements of groundwater for the design and construction of any underground improvements. It may be prudent to make conservative assumptions in the design and construction program.

The Logs of Test Borings including relevant borings and CPT soundings described above are presented in Appendix A. The boring logs in Appendix A were prepared from the field logs which were edited after visual re-examination of the soil samples and the results laboratory tests on selected soil samples as indicated on the logs. Abrupt stratum changes shown on these logs may be gradual and relatively minor changes in soil types within a stratum may not be noted on the logs due to field limitations.

Due to limitations inherent in geotechnical investigations, it is neither uncommon to encounter unforeseen variations in the soil conditions during construction nor is it practical to determine all such variations during an acceptable program of drilling and sampling for a project of this scope. Such variations, when encountered, generally require additional engineering services to attain a properly constructed project. We, therefore, recommend that a contingency fund be provided to accommodate any additional charges resulting from technical services that may be required during construction.

6.0 CORROSION EVALUATION

The corrosion investigation for this project was performed on the selected sample (collected at shallow depths) in general accordance with the provisions of California Test Method 643. For structural elements, Caltrans Corrosion Guidelines (version 3.0, March 2018) consider a site to be corrosive if one or more of the following conditions exist:

• Chloride concentration ≥ 500 ppm

• Sulfate concentration ≥ 1500 ppm

• pH ≤ 5.5

Based on the corrosion test results, the site soil is considered corrosive per Caltrans guidelines due to high concentration of chloride and sulfate. The guidelines presented in the California

Amendments to the AASHTO LRFD Bridge Design Specifications (BDS, 2012), Article 5.12.3, references minimum cement factor and cover thickness for concrete substructures. The Young

Bay Mud is corrosion, and the site is also located in “Marine Environment”. The corrosion potential may have to be considered for buried utilities. The impact on the proposed railroad curves rehabilitation project (embankment construction and rail placement) is considered relatively insignificant.

7.0 SEISMIC DESIGN INFORMATION AND RECOMMENDATIONS

7.1 Seismic Sources

The San Francisco Bay Area lays within one of the most seismically active areas of the North

America and is influenced mostly by the San Andreas Fault System which spans the Coast

Ranges from the Pacific Ocean to the San Joaquin Valley.

The Los Medanos – Roe Island thrust fault is mapped to run through the Project site (Plate

No. 4). The location of the fault as shown is derived from Caltrans Fault Database V2a, 2012, the spatial resolution of which is relatively coarse. The specific location of the fault should not be drawn from this data. The fault is also referred to as the Los Medanos Thrust and is described by Weber-Band et al (1997) as being an active compression-related structure.

Based on Caltrans data base, the Mmax of the fault is 6.8 with an average slip rate of 0.1 mm/year.

In addition, the Concord fault strikes north-west and is located approximately 3.0 miles south-west of the Project area and probably connects with the north-west striking Green

Valley fault across Suisun Bay. The Mmax of the Concord fault is 6.6, and the average slip rate is 4.3 mm/year.

7.2 Seismic Design Criteria

It is our understanding that the project does not involve structural design. For the planned embankment and railroad curves, seismic design is not part of the design scope and not relevant.

7.3 Seismic Hazards

Surface Fault Rupture

Readily available geologic information indicates that the Los Medanos – Roe Island thrust fault is mapped to run through the Project site. There is a fault rupture potential at the site.

Further study on fault displacement is beyond the scope of work. Due to shallow groundwater and general man-placed fill over previous marsh land/estuarine mud deposits, trenching work for fault study is deemed not practical.

The existing railroad tracks have been in service over the years without special mitigation.

The planned railroad curves rehabilitation is in generally vicinity of the existing tracks. In our opinion, the USACE MOTCO needs be notified for a potential fault rupture hazard due to the Los Medanos fault. Maintenance and re-track work may be required as part of the maintenance program, if necessary. For additional information, we have verified the

Alquist-Priolo Special Studies Zones map (Vinehill Quadrangle, USGS 1993). As presented in Plate No. 4B, the MOTCO site is not located within a Alquist-Priolo Special Studies Zone.

Liquefaction

Liquefaction is a phenomenon in which saturated cohesionless soils are subject to a temporary but essentially total loss of shear strength under the reversing, cyclic shear stresses associated with earthquake shaking. Submerged cohesionless sands and low-plastic silts of low relative density are the type of soils that usually are susceptible to liquefaction. Clay is generally not susceptible to liquefaction. According to the AASHTO BDS guidelines (2012), sand and non-plastic silt with corrected SPT blow count (N1)60 less than or equal to 25 are susceptible to liquefaction.

As indicated by Seed, et al. (2003) and Bray, et al. (2004), for soils with sufficient fines content so as to separate the coarser particles and control behavior, liquefaction appears to occur primarily in soils where these fines are either non-plastic or are low plasticity silts or silty clays (PI<12%, and LL<37%), and with high water content relative to their LL (W o> 0.85LL).

Based on the site investigation, the on-site soft peat and organic soils and relaively stiff fine-grained soils are not subject to liquefaction. However, the granular fill and some isolated and sporadic sand lenses/layers mixed within the fine-grained deposits could be are subject to liquefaction, and locally post-liquefaction settlement could be expected.

With a volumetric strain on the order of 3% to 4% per Tokimatsu and Seed (1987), for approximately 10 feet of loose to medium dense sands, the anticipated liquefaction settlement may be on the order of 3 to 5 inches in the general site area and could be randomly distributed. For the planned railroad curves, the general site post liquefaction settlement appears to be tolerable.

8.0 GEOTECHNICAL DESIGN CONSIDERATIONS

The planned railroad curves mainly involve embankment construction and track work. Based on plans provided, new embankment is required with the TOR being typically from grade to up to 2 to 4 feet above the original ground (OG). The embankment width is on the order of 20 feet, except that for Curves 3, 7 and 8, the embankment width may be up to 40 feet wide.

From geotechnical standpoint, the main design consideration is the ground settlement under the planned new track embankments, particularly for curves where deep soft peat and organic soils are indicated from the exploration. Although the planned embankments are not significant, long term consolidation settlements are still anticipated due to the soft and peat soil of the native ground. It is our opinion, the long-term settlements may be tolerable for the curves, and re-track/re-ballast work can be planned in the long-term maintenance program. It does not appear cost effective to mitigate the soft subsoil conditions.

9.0 GEOTECHNICAL RECOMMENDATIONS

9.1 General

This report was prepared specifically for the proposed Project as described earlier. Normal procedures were assumed for construction throughout our analysis and represent one of the bases of recommendations presented herein. The design criteria have been based upon the materials encountered at the site. Therefore, this office should be notified if these conditions change, so that our recommendations can be modified or amended.

9.2 Soil Index Properties and Undrained Shear Strength

As discussed previously in the report, we prepared four sections to present the generalized soil profiles at the site (Plate Nos. 5A through 5E). The index properties of the subsoils are presented on Plate Nos. 6A through 6D. The natural moisture contents clearly indicate where the soft Young Bay Mud is distributed. The stiffer clays and silts typically have moisture contents in the range of 25% to 30%, while the soft peat and organic materials may possess very high moisture contents (up to more than 300%). The peat also has very low density with total unit weight as low as ~65 to 70 pcf (Section B-B’).

The undrained soil strength determination was based on laboratory strength tests (both

Triaxial UU tests and unconfined compression tests) for the fine-grained soils and correlation from CPT soundings. The presentation of the soil strength values vs. depth for the sections are shown in Plate Nos. 7A through 7E. Based on the site-specific data, the soil is softest along Section B-B’ (Curves 9, 10, 11 and 12) by the bay. For Section D-D’ at the

SW Quadrant and South end, we separated the strength plots for Curves 18 & 19, since the north end of T1 bridge appears to have weaker soils by old slough/channel. The strength data were used together with the index properties and consolidation test data to verify the settlement evaluation.

9.3 Embankment Settlement Evaluation

The primary geotechnical design consideration is the potential long-term ground settlement under the new railroad embankments. Based on information provided, the Top of Rail (TOR) for majority of the curves will be near existing grade to up to 2 to 4 feet above

OG. The embankment width is on the order of 20 feet, except that for Curves 3, 7 and 8, the embankment width may be up to 40 feet wide.

Selection of Consolidation Parameters. The analysis was performed using site-specific soil borings and laboratory data obtained from the exploration. The tests included consolidation tests and strength tests (triaxial UU tests and unconfined compression tests for undrained shear strength). For Young Bay Mud, the Su/p ratio is typically in the range of 0.32 based on data provided by previous research. We also compared the data contained in geotechnical literatures and correlations published per Skempton (1957) and NAVFAC

D.M. 7.1. Based on the strength data obtained, the soft Young Bay Mud is predominantly in Normally Consolidated (NC) condition.

For the modified compression index (Cce), we compared the lab data with the relationship shown by Lambe and Whitman (1969) that relates Cc/(1+e0) to natural moisture contents.

The consolidation data are attached at the end of Appendix C for reference. The site investigation data indicate that the properties are consistent with Parikh’s experience of similar soils in the general San Francisco Bay area.

After reviewing the laboratory data and the published literatures, we adjusted the correlation for estimating the modified compression index accordingly for the site soil conditions. For the recompression index (Cr, in the over-consolidated range), it is typically

5% to 10% of the compression index (per Holtz and Kovacs, 1982). In our experience, a 15% to 20% ratio has been common for Cr/Cc. For the project, we have adopted a ratio of 20%

(Cr/Cc) for estimating the modified recompression index. Settlement calculations are attached in Appendix C.

Consolidation Settlements. In summary, the estimated consolidation settlements are shown in the following table. The settlement analysis results are attached in Appendix C of the report.

Table 9.1 Summary of Consolidation Settlements

Proposed Railroad Curves Approximate Site

Location in MOTCO Consolidation Settlements

Cures 13, 14, 15 & 16 NW Quadrant Approx. 2” settlement in OC rang, minimal long-term consolidation settlement Curves 3, 7 & 8 NW Quadrant & Middle

Curves 9, 10, 11 & 12 NE Quadrant Approx. 2” settlement in OC range, up to 6” long-term consolidation settlement

Curves 17 & 20 SE Quadrant Approx. 1.5” settlement in OC range, up to 1.5” long-term consolidation settlement

Curves 18 & 19 South End Approx. 1.5” settlement in OC range, Minimal long-term consolidation settlement

Curves 1, 2, 4, 5 & 6 SW Quadrant Approx. 3” settlement in OC range, up to 1” long-term consolidation settlement

The settlements in Over-Consolidated (OC) range are expected to occur relatively fast and may complete by the end of earthwork construction. The settlements in the NC range will take very long time to occur due to peat and organic nature of the soil. For Curves 9, 10, 11 & 12 along the bay margin, we check with ~15 feet of peat and organic soil with double drainage condition and a coefficient of consolidation value (Cv) of 0.005 ft2/day, the time required to achieve 90% consolidation is:

t = x Hdr 2/Cv , = 0.848 for 90% consolidation, Hdr = 7.5 feet, Cv = 0.005 ft2/day t = (0.848)(7.5x7.5)/0.005 = 9540 days ~= 26 years

In our opinion, the consolidation settlements may be tolerable for the planned railroad curves. It may be more practical to plan the re-track or re-ballast work in the long-term maintenance program. It may not be cost effective to mitigate the long-term ground settlement for the planned railroad curves rehabilitation.

In addition to the primary consolidation settlement, secondary long-term consolidation settlement is also anticipated due to peat and organic nature of the soils with natural moisture content up to 300%. We anticipate a secondary settlement on the order of 1 inch in about 50 years for Curves 9, 10, 11 & 12 area.

9.4 Trackway Support and Grading

The proposed railroad curves are close to existing tracks, but the existing terrain may require small amount of embankment to meet the finish grade.

Soil Conditions at Shallow Depth

The existing soil curst at shallow depth consists of man-made fill placed over the years.

Thus, the fill could vary in composition and may include local clays, silts of granular fill over old marsh land. The borings confirmed the variability of the existing fill at shallow depth including some old asphalt concrete. The site is next to Suisun Bay, and the existing site grade is generally at Elev. 10 feet. Shallow groundwater is anticipated. For project design, we have assumed groundwater at five (5) feet depth.

Grading

All grading operations should be performed in accordance with the project specifications and USACE standards. A representative from our office or the regulatory agency should observe the grading operation and perform moisture and density tests on prepared subgrade and compacted fill. Should there be any alterations of the proposed construction that will affect the stated bases of our recommendations, we should be informed so that we can review such changes and amend or submit additional recommendations.

Subgrade Preparation Subgrade preparation including cutting, shaping, filling, backfilling, and embankment construction should conform to the project specifications. On areas require embankment, all stump, roots, etc., shall be removed to a minimum of 2 feet below the existing grade.

Areas requiring minimal grubbing shall have a minimum of 6 inches of vegetation and topsoil removed. After the subgrade is scarified and recompacted, the subgrade should be observed by the geotechnical engineer (such as by proof rolling) prior to placing the new embankment material.

Note that it is common to encountered soft, pumping or unsuitable material during subgrade preparation. This is a typical earthwork construction issue in the field that the contractor should be prepared for. If soft/pumping or unsuitable subgrade soil is encountered but not feasible to fully remove and replace, we recommend over-excavating minimum 18 to 24 inches below subgrade, laying a layer of geotextile fabric or geogrid, and replace with additional subballast to facilitate further earthwork operation. The actual locations of the over-excavations/backfill placement may vary depending on the soil conditions encountered in the field. Our office or the Agency should observe the grading operation.

Import Material Import borrow for embankment construction should be free from contamination, organics and other deleterious material and conform to the project specifications. In addition, the material should maximum Plasticity Index (PI) of 25 and no particles larger than 4 inches in sizes. The ballast and subballast material should conform to standard specifications.

The moisture content of the soil at the time of compaction should be at the optimum moisture content (W%opt) or within minus four (-4) percentage points of the W%opt per

ASTM D1557. Further details should be referred to the project standard specifications.

Compaction Requirements Subgrade and general fill placed on the site should be compacted by mechanical means.

Jetting or flooding should not be allowed for the project. The compaction should not be less than 90% relative compaction as determined by ASTM D-1557. It is recommended that subgrade within 3 feet below the finish grade should be compacted to minimum 95% relative compaction per ASTM D1557.

Slope Ratios For temporary fill and cut slopes above groundwater level, a slope ratio of up to 1H:1V may be used. For permanent fill and cut slopes, a minimum slope ratio of 2H:1V is recommended. It should be noted that local irregularities such as sand and gravel pockets and layers may be encountered. This may require flattening of the slopes.

9.5 Working Platform

Soft and loose, saturated native soil deposits may be encountered at subgrade or bottom of excavation. In such case, working conditions at soft/pumping subgrade may become difficult, and equipment may lose mobility, etc. The contractor should take adequate measures to minimize the disturbance of the sensitive deposits at the subgrade. The contractor may minimize the disturbance of sensitive deposits or mitigate existing soft ground conditions by constructing a working platform at the subgrade. Note the discussion provided for subgrade preparation in Section 9.4 of the report. The contractor may use other methods of subgrade stabilization. The contractor’s proposed method should be reviewed by the Geotechnical Engineer.

9.6 Drainage

Since soils generally tend to lose strength when they become wet, it is essential that drainage be properly controlled. The site should be graded to provide positive drainage away from all tracks/pavement sections so that water does not collect or discharge to undermine the developments. Landscaping within 5 feet of the perimeter of the foundations and developments should be avoided to reduce the potential for ponding and saturation of the foundation soils.

Runoff from roof and paved areas should be collected and drained to suitable discharge points. Usually, this drainage is connected to the storm drainage system. The site grading should not be altered or ditched, and drains should not be blocked as a result of future landscaping or any other future construction activities.

10.0 CONSTRUCTION OBSERVATION

The performance of any structure is dependent upon construction procedures and quality.

Hence, observation of grading operation should be carried out by the Geotechnical Engineer. If the encountered subsurface conditions differ from those forming the basis of our recommendations, this office should be informed in order to assess the need for design changes.

Therefore, the recommendations presented in this report are contingent upon good quality control and these geotechnical observations during construction.

Prospective contractors for the Project must evaluate construction-related issues on the basis of their own knowledge and experience in the local area, on the basis of similar projects in other localities, or on the basis of field investigation on the site performed by them, taking into account their proposed construction methods and procedures. In addition, construction activities related to excavation and lateral earth support must conform to safety requirements of OSHA and other applicable municipal and State regulatory agencies.

11.0 INVESTIGATION LIMITATIONS

Our services consist of professional opinions and recommendations made in accordance with generally accepted geotechnical engineering principles and practices and are based on our site reconnaissance and the assumption that the subsurface conditions do not deviate from observed conditions. No warranty, either expressed or implied, of merchantability or fitness, is made or intended in connection with our work or by the furnishing of oral or written reports or findings.

The scope of our services did not include any environmental assessment or investigation for the presence or absence of hazardous or toxic materials in structures, soil, surface water, groundwater or air, below or around this site.

Unanticipated soil conditions are commonly encountered and cannot be fully determined by taking soil samples and excavating test borings; different soil conditions may require that additional expenditures be made during construction to attain a properly constructed project.

Some contingency fund is thus recommended to accommodate these possible extra costs.

This report has been prepared for the proposed Project as described earlier, to assist the engineer in the design of this Project. In the event any changes in the design or location of the facilities are planned, or if any variations or undesirable conditions are encountered during construction, our conclusions and recommendations shall not be considered valid unless the changes or variations are reviewed, and our recommendations modified or approved by us in writing.

This report is issued with the understanding that it is the Designer's responsibility to ensure that the information and recommendations contained herein are incorporated into the project and that necessary steps are also taken to see that the recommendations are carried out in the field.

The findings in this report are valid as of the present date. However, changes in the subsurface conditions can occur with the passage of time, whether they are due to natural processes or to the works of man, on this or adjacent properties. In addition, changes in applicable or appropriate standards occur, whether they result from legislation or from the broadening of knowledge.

Accordingly, the findings in this report might be invalidated, wholly or partially, by changes outside of our control.

Respectfully submitted, PARIKH CONSULTANTS, INC.

Y. David Wang, Ph.D., P.E. 52911 Gary Parikh, P.E., G.E. 666 Senior Engineer Project Manager

CONTRA COSTA COUNTY, CALIFORNIA

JOB NO.: 2019-132-GEO PLATE NO.: 1

PROJECT LOACATION MAP

PROJECT LOCATION MAP

Source: Google Map

10000 ft

PROJECT

LOCATION

CONTRA COSTA COUNTY, CALIFORNIA

JOB NO.: 2019-132-GEO PLATE NO.: 2

BORING LOCATION MAP

hole

RAILROAD REHABILITATION PROJECT

CONTRA COSTA COUNTY, CALIFORNIA

JOB NO.: 2019-132-GEO PLATE NO.: 3A

CONTRA COSTA COUNTY, CALIFORNIA

JOB NO.: 2019-132-GEO PLATE NO.: 3B

YOUNG BAY MUD THICKNESS CONTOUR

PROJECT LOCATION

Reference: Geologic and Engineering Aspects of San Francisco Bay Fill, CDMG Special Report 97, 1969

JOB NO.: 2019-132-GEO PLATE NO.: 4A

JOB NO.: 2019-132-GEO PLATE NO.: 4B

RAILAROAD REHABILITATION PROJECT

MOTCO site

CONTRA COSTA COUNTY, CALIFORNIA

JOB NO.: 2019-132-GEO PLATE NO.: 5A

A

B B'

C

C'

D

D'

A'

SECTION LOCATION MAP

GenerallyGGGG stiffffff to very stiffffff fine-grainedddddgraragraragg aa claysccc & silts, some sand lensesllelele

GenerallyGGGGGGGGGGGGGGGG stiffiii ffff tottottoooooo veryvvvvvvvv yyyyyyyyyyryryyyyyrr stifffff fine-graineddddddddddddddddddddd clayscccccccccccccc & silts,,, somesososs mmmmmemeeeee sandssaaananndndddss lenseslllllll

Dwang Text Box

PLATE NO. 5B

Containsoooooooooooooooo Peat dddddddddddannnnnndnddnndndndnnnndddndnddnnn organicgggggg clayyyyy thru Elev.EEEEEEEEEEllllllllllllllllllll -25',, with %%%%%wwww%%ww%%%%w%%%w%%w up tot 300%3300000%% and soft inn consistency,tttccccccccc someossoossososossoommmmmmmeeesoosssososoososoossssoososoo sandsssandsssaaaaannddddddd lenses

Generallyeee stiff to very stiff fine-eee grainednnn clays & siltssss

Dwang

PLATE NO. 5C

Generally stiff to veryee stiff fine-grained clayscc &&&& silts,ttli some sandddd lenses.l LocallylllLLL may havehhhhhh soft organic clays withww high moisture contentoo

Dwang

PLATE NO. 5D

ContainsCCCC Peataaa and organiciicicc clay thru Elev.EEE -38' nearnn slough/channel//c/c/c area,, with w% up to ~100% andaaa soft in consistency,ooo somesss sand lensesnn rallylllGenernnnnnnenenenenenee rarararararaaaaaaaaarr stiff to veryyyy stiff fine-grainedaa edddddddddededed claysc aaaaaaaaaaaaayyyyyyaa & silts,iiiiiiililltlttstststsss somesssssssss sand lenses.nn Locallyyyy mayyyyyyyyyyyyyyyyyyy haveaaaaaaaa ofttffsoftooss ffffffofofooofofffftft rganiccciinnaaggrgr aaorroorrrrrrrrrrrrrr claysssysyyaalclcc withhhthtiwww ttt highhhghggihhh moistureeereruututssisioommmm ttt tenttnnneetnttconnnooocccccccccccccc ttttttttttttttttnn

Dwang

PLATE NO. 5E

SECTION A-A'

CURVES 3, 13, 14, 15 & 16

(NW QUADRANT)

PLATE NO.: 6A

SECTION B-B'

CURVES 9, 10, 11 & 12

(NE QUADRANT)

PLATE NO.: 6B

SECTION C-C'

CURVES 17 & 20

(SE QUADRANT)

PLATE NO.: 6C

SECTION D-D'

CURVES 1, 2, 4, 5, 6, 18 & 19

(SW QUADRANT & SOUTH END)

PLATE NO.: 6D

USACE MARINE OCEAN TERMINAL CONCORD (MOTCO)

CONTRA COSTA COUNTY, CALIFORNIA

JOB NO.: 2019-132-GEO PLATE NO.: 7A

0 500 1000 1500 2000 2500 3000 3500 4000 D ep th

, f t

Undrained Shear Strength, psf

Su (CPT-3) Su (CPT-5) Su (CPT-9) B-2 (UC test) B-6 (UC test) B-6 (UU test) B-7 (UC test) B-8 (UC test) B-8 (UU test) B-13 (UC test) Recommended Design Strength B-4 (Torvane)

SECTION A-A'

CURVES 3, 7, 8, 13, 14, 15 & 16 (NW Quadrant)

CONTRA COSTA COUNTY, CALIFORNIA

JOB NO.: 2019-132-GEO PLATE NO.: 7B

0 500 1000 1500 2000 2500 3000 3500 4000 D ep th

, f t

Undrained Shear Strength, psf

Su (CPT-16) Su (CPT-19) B-15 (UC test) B-15 (UU test) B-17 (UC test) B-17 (UU test) B-18 (UC test) B-18 (UU test) B-20 (UC test) B-20 (UU test) Recommended Value B-15 (Torvane) B-20 (Torvane)

SECTION B-B'

CURVES 9, 10, 11 & 12 (NE Quadrant)

CONTRA COSTA COUNTY, CALIFORNIA

JOB NO.: 2019-132-GEO PLATE NO.:

0 500 1000 1500 2000 2500 3000 3500 4000 D ep th

, f t

Undrained Shear Strength, psf

Su (CPT-23) Su (CPT-25) B-21 (UC test)

B-22 (UC test) B-24 (UC test) Recommended Value

SECTION C-C'

CURVES 17 & 20 (SE Quadrant)

CONTRA COSTA COUNTY, CALIFORNIA

JOB NO.: 2019-132-GEO PLATE NO.:

0 500 1000 1500 2000 2500 3000 3500 4000 D ep th

, f t

Undrained Shear Strength, psf

Su (CPT-26) Su (CPT-27) Su (CPT-28)

B-29 (UC test) Recommended Value

SECTION D-D', SOUTH PART

CURVES 18 & 19 (South End)

CONTRA COSTA COUNTY, CALIFORNIA

JOB NO.: 2019-132-GEO PLATE NO.:

0 500 1000 1500 2000 2500 3000 3500 4000 D ep th

, f t

Undrained Shear Strength, psf

Su (CPT-12) B-10 (UC Test) B-10 (UU test) B-11 (UC test) B-30 (UC test) B-31 (UC test) B-31 (UU test) Recommended Value B-31 (Torvane) B-11 (Torvane)

SECTION D-D', NORTH PART

CURVES 1, 2, 4, 5 & 6 (SW Quadrant)

Dwang

APPENDIX A

(Rotary Wash Boring Data)

Job No.:

GROUP SYMBOLS AND NAMES

DRILLING METHOD SYMBOLS

Auger Drilling

FIELD AND LABORATORY TESTS

WATER LEVEL SYMBOLS

Dynamic Cone or Hand Driven Diamond CoreRotary Drilling

Static Water Level Reading (long-term)

Shelby Tube

NX Rock Core

Bulk Sample

Piston Sampler

HQ Rock Core

Other (see remarks)

Static Water Level Reading (short-term)

First Water Level Reading (during drilling)

SILTY, CLAYEY SAND with GRAVEL

CLAYEY SAND with GRAVEL

SILTY SAND with GRAVEL

COBBLES

Standard Penetration Test (SPT)

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

SAMPLER GRAPHIC SYMBOLS

OL

OL

CH

MH

OH

OL/OH

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

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

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

Poorly graded SAND with SILT and GRAVEL

SANDY lean CLAY

GRAVELLY lean CLAY

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

SILTY, CLAYEY SAND

Group Names

SC-SM

Graphic / Symbol Graphic / Symbol Group Names

GC

GP

GC-GM

SP-SC

SW

SP

SW-SM

SILTY, CLAYEY GRAVEL with SAND

CLAYEY GRAVEL with SAND

SILTY GRAVEL with SAND

Standard California Sampler

Modified California Sampler

Well-graded SAND with SILT

SW-SC

SP-SM

Consolidation (ASTM D 2435-04)

Compaction Curve (CTM 216 - 06)

Liquid Limit, Plastic Limit, Plasticity Index

(AASHTO T 89-02, AASHTO T 90-00)

Collapse Potential (ASTM D 5333-03)

Sand Equivalent (CTM 217 - 99)

Corrosion, Sulfates, Chlorides (CTM 643 - 99;

CTM 417 - 06; CTM 422 - 06)

GRAVELLY SILT

GRAVELLY SILT with SAND

SILT

ORGANIC SILT with SAND ORGANIC SILT with GRAVEL

SANDY ORGANIC SILT

C

Consolidated Undrained Triaxial (ASTM D 4767-02)

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

GRAVELLY ORGANIC SILT

GRAVELLY ORGANIC SILT with SAND

ORGANIC SILT

PI

Particle Size Analysis (ASTM D 422-63 [2002])

Point Load Index (ASTM D 5731-05)

R-Value (CTM 301 - 00)

Specific Gravity (AASHTO T 100-06)

Shrinkage Limit (ASTM D 427-04)

Swell Potential (ASTM D 4546-03)

Pocket Torvane

Unconfined Compression - Soil (ASTM D 2166-06) Unconfined Compression - Rock (ASTM D 2938-95)

CL

CU

PL

Pressure MeterPM

Pocket Penetrometer

SG

SW

TV

UC

Well-graded SAND with CLAY and GRAVEL (or SILTY CLAY and GRAVEL)

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

UU Unconsolidated Undrained Triaxial

(ASTM D 2850-03)

UW Unit Weight (ASTM D 4767-04)

Vane Shear (AASHTO T 223-96 [2004])VS

CP

PP

R

SL

CR

SE

Direct Shear (ASTM D 3080-04)DS

Expansion Index (ASTM D 4829-03)EI

Moisture Content (ASTM D 2216-05)M

OC Organic Content (ASTM D 2974-07)

Permeability (CTM 220 - 05)P

PA

Well-graded GRAVEL

Poorly graded GRAVEL with SILT

GRAVELLY lean CLAY with SAND

BORING RECORD LEGEND

Date:

Plate:This log is part of the report prepared by Parikh Consultants, Inc. for the named project and should be read together with that report for complete interpretation. This summary applies only at the location of this boring and at the time of drilling. Subsurface conditions may differ at other locations and may change at this location with the passage of time. The data presented is a simplification of actual conditions encountered.

USACE MILITARY OCEAN TERMINAL CONCORD (MOTCO)

RAILROAD REHABILITATION PROJECT

CONTRA COSTA COUNTY, CA

March 2021 2019-132-GEO

Appendix A

Job No.:

2.0 - 4.0

> 4.0

2.0 - 4.0

Pocket Penetrometer (tsf)

Soft 0.25 - 0.50 0.25 - 0.50 0.12 - 0.25

< 0.25

0.25 - 0.500.50 - 1.00.50 - 1.0Medium Stiff

Hard

Very Stiff

Low

Very Loose

Loose

SPT N60 - Value (blows / foot)

PLASTICITY OF FINE-GRAINED SOILS

Cobble Coarse Fine No. 4 Sieve to 3/4 inch Coarse No. 10 Sieve to No. 4 Sieve

No. 40 Sieve to No. 10 SieveMedium Fine No. 200 Sieve to No. 40 Sieve

0.50 - 1.01.0 - 2.01.0 - 2.0Stiff

CONSISTENCY OF COHESIVE SOILS

SizeDescriptor

Silt and Clay Passing No. 200 Sieve

Absence of moisture, dusty, dry to the touchDry

Damp but no visible water

Descriptor

Dense

Medium Dense

5 - 10

11 - 30

0 - 4

31 - 50

Descriptor

Moist

MOISTUREAPPARENT DENSITY OF COHESIONLESS SOILS

Wet

> 50Very Dense

Criteria

Visible free water, usually soil is below water table

Descriptor Field Approximation Unconfined Compressive Strength (tsf) Torvane (tsf)

Easily penetrated several inches by thumb

Can be penetrated several inches by thumb with moderate effort

Readily indented by thumb but penetrated only with great effort

PERCENT OR PROPORTION OF SOILS

Sand

Boulder

Criteria

Trace

Gravel

Descriptor

> 12 inches

3/4 inch to 3 inches 3 to 12 inches

5 to 10%Few

15 to 25%Little

30 to 45%Some

50 to 100%Mostly

Nonplastic

High

Easily penetrated several inches by fist

Readily indented by thumbnail

Indented by thumbnail with difficulty

Descriptor Criteria

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.

CEMENTATION

Descriptor Criteria

Medium

Strong

Moderate

Weak

Crumbles or breaks with considerable finger pressure.

Particles are present but estimated to be less than 5%

Will not crumble or break with finger pressure.

Crumbles or breaks with handling or little finger pressure.

SOIL PARTICLE SIZE

It takes considerable…