Attachment 8 Geotech Supplemental 3.pdf

Austin • Corpus Christi • Eagle Pass • Fort Worth • San Antonio

To: Mr. Jon C. DeLay, P.E. Date: October 8, 2020

Company: Merrick & Company Page: 1 of 11

From: Jerry D. Shepherd, P.E., D.GE Arias Job No.: 2018-933 Kacy M. Crawford, P.E.

Subject: Supplemental Letter #3 Drilled Pier Parameters: USDA ARS KBUSLIRL New Cattle Working Barn Kerrville, Texas

Arias Geoprofessionals, Inc. (Arias) previously prepared a geotechnical engineering study for the above referenced project. The results of our study were originally presented in the Arias

Geotechnical Engineering Study Report, 2018-933, dated May 29, 2019 and revised on July

3, 2019. Supplemental Letter #1 dated January 10, 2020 provided additional foundation recommendations, and Supplemental Letter #2 dated April 21, 2020 provided retaining wall design parameters.

The proposed project will consist of the construction of a new cattle working barn with an earthen floor at the USDA ARS KBUSLIRL facility in Kerrville, Texas. In the original report, recommendations were provided for the barn to be supported on a slab on grade foundation, and in Supplemental Letter #1, recommendations were provided for a mud mat foundation.

This supplemental letter is to provide design criteria for the drilled piers, and applicable construction recommendations. One (1) additional boring was drilled at the site, to provide additional data and a summary of the field work completed is also included in this letter.

A site vicinity map is provided in Appendix A, Figure 1 of this report.

Field Exploration One (1) soil boring was drilled at the approximate location shown on the Boring Location

Plan provided as Figure 2 in Appendix A. Boring B-15 was drilled to a depth of thirty-five (35) feet below the existing ground surface that existed on September 15, 2020. Boring data is summarized in the following table.

Table 1: Boring Locations

Boring No. Structure Depth, ft As Drilled Coordinates

Latitude Longitude

B-15 Cattle Barn 35 30° 4' 23.16" N 99° 6' 41.51" W

Note: Borings B-1 through B-14 are summarized in the original Geotechnical Report dated May 29, 2019 and revised on July 3, 2019.

Supplemental Letter #3 Arias Geoprofessionals Arias Job No. 2018-933

The boring was sampled in accordance with ASTM D1586 procedures for Split Spoon sampling techniques as described in Appendix C of the original report. A truck-mounted drill rig using continuous flight augers together with the split spoon sampler was used to secure the subsurface soil samples. The boring was backfilled with soil cuttings generated during the drilling process.

Soil classifications and borehole logging were conducted during the exploration by our engineering technician working under the supervision of the Project Geotechnical Engineer.

Final soil classifications, as seen on the boring log included in Appendix B, were determined by the Project Geotechnical Engineer based on laboratory and field test results and applicable ASTM procedures. A key to the terms and symbols used on the boring log is also included in Appendix B.

Laboratory Tests As a supplement to the field exploration, laboratory testing was performed to determine soil water content, Atterberg Limits, and percent passing the US Standard No. 200 sieve. The laboratory test results are reported in the attached boring log included in Appendix B and the soil laboratory testing for this project was done in accordance with applicable ASTM procedures (as noted in Appendix C of the original report). Remaining soil samples recovered from this exploration will be routinely discarded following submittal of this report.

Subsurface Conditions Generalized stratigraphy and groundwater conditions encountered are discussed in the following sections. The subsurface and groundwater conditions are based on conditions encountered at the boring locations to the depths explored.

Geology

Geology at the site is mapped as Fluviatile Terrace Deposits (Qt), underlain by the Glen

Rose (Kgr) formation.

The Fluviatile Terrace Deposits are alluvium soils which are floodplain deposits and consist primarily of clays, along with various amounts of silt, sand, and gravel. These materials are typically tan to gray in color, although significant variation can occur across the site.

Localized zones of the alluvial soils encountered may include significant gravel deposits, which will typically contain angular, and cherty material. Because of the potential for increased permeability within the gravels relative to the much lower permeabilities of the underlying formational soils, a “perched” water zone could be encountered at the contact between the gravels and underlying clay formation. Due to the alluvial nature of these deposits, significant variations can occur over short distances.

Glen Rose Marlstone is an extensive formation along many areas north and west of the San

Antonio Area and can reach an overall thickness of over 1,000 feet. This formation consists of hard Marlstone strata, that alternate with marl or marly Marlstone, which is typically softer and prone to a higher degree of weathering and void development. This rock is typically fine grained to aphanitic and can be highly fossiliferous containing predominantly marine fossils.

Voids can occur, which are typically filled with either clay, or sandy clay, and may be up to several feet in diameter.

Site Stratigraphy and Engineering Properties

The generalized subsurface stratigraphy encountered at the location of Boring B-15 is summarized in Table 2 below. The presence and thickness of the various subsurface materials can be expected to vary away from and between the exploration locations. The descriptions generally conform to the Unified Soils Classification System.

Table 2: Generalized Subsurface Conditions: Boring B-15

Stratum Depth

(ft) Material Type

PI

range

No. 200 range

N range

II 0 to 2 Gray and Light Brown –

SANDY LEAN CLAY (CL) –

very stiff

21* 56* 17*

III 2 to 35

Tan, Light Gray and Tan – MARLSTONE – very hard

Lean Clay filled void from 4 to

8 feet

-- -- **50/1 - **50/5

Note: Stratum I soils were encountered in borings drilled during the initial geotechnical study. They were not encountered in this phase of work.

Where: Depth - Depth from existing ground surface at the time of geotechnical study, feet PI - Plasticity Index, % No. 200 - Percent passing #200 sieve, N - Standard Penetration Test (SPT) N-value, blows per foot

* - Only one test in Stratum -- - No test applicable in Stratum ** - Indicates blows during seating penetration

Groundwater

A dry soil sampling method was used to obtain the samples at the project site, and groundwater was not encountered during field operations on September 15, 2020.

Groundwater levels will often change significantly over time and should be verified immediately prior to construction.

Water levels in open boreholes may require several hours to several days to stabilize depending on the permeability of the soils. Groundwater levels at this site may differ during construction because fluctuations in groundwater levels can result from seasonal conditions, rainfall, drought, or temperature effects. Pockets or seams of gravels, sands, silts or open fractures and joints can store and transmit “perched” groundwater flow or seepage. Should dewatering become necessary, it is considered means and methods and is solely the responsibility of the contractor.

Drilled Piers Foundation Recommendations A drilled pier foundation is being considered for the Cattle Working Barn. Recommendations for evaluation of axial capacity and lateral capacity are presented in the Tables 3 and 4 below. Pier capacities for axial loading were evaluated using the design methodologies included in FHWA-IF-99-025 - Drilled Shafts: Construction Procedures and Design Methods.

Both end bearing and side friction resistance may be used in evaluating the allowable bearing capacity of the pier shafts.

Table 3: Drilled Pier Design Parameters Axial Capacity

Depth Material

Recommended Design Parameters

Allowable Skin

Friction, psf

Allowable End

Bearing, psf

Uplift Force, kips

0 to 5 Sandy Lean Clay & Marlstone with clay filled void Neglect

5 to 8 Marlstone with a lean clay filled void - --

25*D 8 to 35

Very hard & weathered Marlstone with clay filled voids

1,000 10,000

Constraints to be Imposed During Pier Design

Minimum depth of drilled piers, (measured from surface)

A minimum depth of 15 to 25 feet is recommended.

Deeper depths may be required to resist compressive, uplift, pullout, or lateral loads as determined by the Project Structural Engineer. If piers are designed to be deeper than 35-feet, we should be contacted to provide additional borings and recommendations.

Minimum shaft diameter 18 inches

Minimum Void Space Below Grade Beams and Pier Caps

12 inches

Notes:

1. For straight shaft piers, the contribution of the soils for the top eight feet of soil embedment and for a length equal to at least 1 pier diameter from the bottom of the shaft should be neglected in determination of friction capacity for compression loading. The recommended design parameters include a factor of safety of 2 for skin friction and of 3 for end bearing.

2. Total and differential settlement of piers is expected to be less than 1 inch and ½ inch, respectively. Estimated settlements are based on performance of properly installed piers in the Kerrville, Texas area. A detailed settlement estimate is outside of the scope of this service.

3. Sufficient reinforcing steel should be placed within the pier to account for tension and lateral loading as applicable.

Pier vertical reinforcing steel should be designed to resist the uplift forces from swelling soils and uplift and lateral forces from wind loading. The final reinforcing requirements should be determined by the project structural engineer.

Tensile rebar steel should be designed in accordance with ACI Code Requirements.

4. A minimum shaft diameter of 18 inches is recommended. Larger shaft diameters may be required. Straight shaft piers should be spaced at least 3 diameters apart center-to-center. If the recommended pier spacing cannot be maintained, Arias should be consulted to consider the group effect of closely spaced piers.

5. The uplift force resulting from expansion of soils in the active zone may be computed using the above formula where D is the shaft diameter in feet. For drilled straight-sided piers, the contribution from soils to resist uplift is the allowable skin friction resistance of the soils below the basement floor slab. For uplift loading only, the allowable skin resistance for the bottom 1 pier diameter can be used to size the pier. Sustained dead loads will also aid in resisting uplift forces. Pier depths greater than 30 feet may be required to: (1) resist expansive soil uplift forces, and/or (2) as a result of axial or lateral loading requirements.

Lateral pile analyses including capacity, maximum shear, and maximum bending moment will be evaluated by the project structural engineer using LPILE or similar software. In the following table, Arias presents geotechnical input parameters for the encountered soils at the

Cattle Working Barn site. Please note that the depths to the top and bottom of each layer were interpreted using approximate elevation data at the explored boring location and layer boundaries as shown on the boring log.

Table 4: Drilled Pier Geotechnical Input Parameters for LPILE Analyses

Depth, (ft) Material e ER qur RQD Krm

0 - 8 Sandy Lean Clay & Marlstone with clay filled void NEGLECT

8 - 35 Very hard & weathered

Marlstone with clay filled voids 130 150,000 1,000 25 0.0005

Note: The parameters given above are for use in the “Weak Rock” criteria for the LPILE analysis.

Where: Depth: Stratum depth in feet from below the existing ground surface on 9/15/2020 ge : Effective unit weight, pcf Er : Young’s modulus for weak rock, psi qur : Uniaxial compressive strength, psi RQD: Rock Quality Designation, % Krm : Axial strain parameter for weak rock

Table 5: Summary of Pilot Hole Requirements

Foundation Type Summary of Pilot Program

Drilled Pier

Pilot holes should be performed at each pier location at a minimum depth below the expected pier tip elevation of 2 pier diameters, or 10 feet, whichever results in a deeper pilot hole.

(Not required if piers are designed as frictional units, i.e. supported by side friction only without an end-bearing component)

Notes:

1. All pilot holes should be grouted using a lean concrete having a 28-day compressive strength of at least 3,000 psi.

2. Arias can assist in developing a pilot hole schedule to meet the above criteria once the type of foundation system has been selected, and once the foundation layout has been determined.

3. Pilot holes are typically performed with a small diameter drill (i.e. ½ inch or similar). The pilot hole program should be monitored by a representative of Arias Geoprofessionals.

The subsurface conditions encountered during the field exploration at the project site indicates that the depth to competent rock could vary, and there is a potential for encountering voids.

pfinley Cloud+ pfinley Cloud+ something is not correct here pfinley Cloud+ pfinley Cloud+ need add to notes and specs

Variations in bedrock depths is common in the Glen Rose Marlstones which may be the result of the uneven weathering, voids, softer layers, and clay seams that can be present. A

Lean Clay (CL) filled void was also encountered in the boring. The presence of these conditions reduces the side resistance along the shafts, and if they are unknowingly present below the pier tip elevations, the end bearing capacity of the piers could be significantly less than the design values. The following two design approaches can be taken. Pilot hole recommendations are presented below as well as previously in Table 5 (Summary of Pilot

Hole Requirements).

If a karst feature is encountered during construction and/or pilot hole drilling, we should be notified immediately so that we may evaluate the feature and its potential impacts on the proposed construction. Minor solution features are often grouted with lean concrete or flowable fill. Arias should be provided an opportunity to evaluate Karst features on a case-by-case basis and provide geotechnical recommendations as appropriate.

Design the Piers for Side Friction and End Bearing - If fractured rock with voids, and/or clay filled seams/layers are encountered during the drilling of a pier, the pier length should be extended an additional length equal to the thickness of the non-rock material to achieve the required side friction. For example, once competent bedrock is encountered, if a one-foot thick clay layer is encountered within the bedrock during drilling, the pier should be extended an additional foot of depth into the underlying competent bedrock.

If fractured rock with voids, and/or clay filled seams/layers conditions is present below the pier tip elevation, the design end bearing capacity may not be achieved.

Accordingly, if the pier is designed for end bearing, it will be necessary to check for the presence of apparent non rock bearing conditions by drilling a “pilot hole” that extends at least two (2) pier diameters or 10 feet below each pier bottom, whichever results in the deeper pilot hole. If fractured rock with voids, and/or clay seams/layers conditions are encountered in the pilot hole, it will be necessary to extend the pier bottom a minimum of one (1) pier diameter below the fractured rock with voids, and/or clay filled seams/layers in order to use the design end bearing capacity (i.e. this is in addition to extending the pier depth for side friction considerations previously noted).

A representative of the Geotechnical Engineer must be present to verify that all of the pilot holes are taken to the recommended depth including the additional pier depths when clay-filled seams/layers or a void is encountered in the pilot holes.

Design the Piers for Side Friction Only – An alternative to performing pilot holes is to design the piers for side friction only (i.e. end bearing is neglected). If fractured rock with voids, and/or clay filled seams/layers conditions is encountered during the drilling of a pier, the pier length would have to be extended an additional length equal pfinley Cloud+ pfinley Cloud+ add to notes and specs to the thickness of the non-rock material to achieve the required side friction. For example, once competent bedrock is encountered, if a one-foot thick clay layer is encountered within the bedrock during drilling, the pier should be extended an additional foot into the underlying competent bedrock. Pilot holes will not be required for drilled piers designed using side friction only

Drilled Piers Construction Considerations

The contractor should verify groundwater conditions before production pier installation begins. Comments pertaining to high-torque drilling equipment, groundwater, slurry, and temporary casing are based on generalized conditions encountered at the explored locations. Conditions at individual pier locations may differ from those presented and may require that these issues be implemented to successfully install piers. Construction considerations for drilled pier foundations are outlined in the following table.

Table 6: Drilled Pier Installation Considerations

Recommended installation procedure FHWA-NHI-10-016, May 2010

High-torque drilling equipment anticipated

Yes; dense and very hard clayey soils and Marlstone encountered

Groundwater anticipated Possible, not encountered during field operations

Temporary casing anticipated Possible, only if drilling conditions require

Slurry installation anticipated Possible if subsurface soil and groundwater conditions dictate

Concrete placement

Same day as drilling. If a pier excavation cannot be drilled and filled with concrete on the same day, temporary casing or slurry may be needed to maintain an open excavation. The concrete should be placed using a tremie or pump and not allow the concrete to ricochet off the reinforcing cage or side pier side walls.

Maximum water accumulation in excavation at time of concrete placement

2 inches - MAXIMUM

Concrete installation method needed if water accumulates

Tremie or pump to displace water beginning at the bottom of the pier excavation.

Quality assurance monitoring

Geotechnical engineer’s representative should be present during drilling of all piers, should observe drilling and verify the installed depth and diameter, should verify material type at the base of excavation and cleanliness of base, and should observe placement of reinforcing and concrete.

Notes:

1. The contractor should verify groundwater conditions before production pier installation begins. Temporary casing may be needed due to groundwater conditions, dependent on seasonal conditions. Payment provisions for temporary casing and for placement of concrete by the tremie method are recommended for inclusion in the Contract Documents.

2. Comments pertaining to high-torque drilling equipment, groundwater, temporary casing, and slurry drilling methods are based on generalized conditions encountered at the explored locations. Importantly, these are considered means and methods and are the sole responsibility of the contractor. Conditions at individual pier locations may differ from those presented and may require that these techniques be implemented to successfully install piers.

3. The following installation techniques will aid in successful construction of the shafts:

a. The clear spacing between rebar or behind the rebar cage should be at least 3 times the maximum size of coarse aggregate.

b. Centralizers on the rebar cage should be installed to keep the cage properly positioned.

c. Cross-bracing of a reinforcing cage may be used when fabricating, transporting, and/or lifting.

However, experience has shown that cross-bracing can contribute to the development of voids in a concrete shaft. Therefore, we recommend the removal of the cross-bracing prior to lowering the cage in the open shaft.

d. The use of a tremie should be employed so that concrete is directed in a controlled manner down the center of the shaft to the pier bottom. The concrete should not be allowed to ricochet off the pier reinforcing steel nor off the pier side walls.

e. The pier concrete should be designed to achieve the desired design strength when placed at a 7-inch slump, plus or minus 1-inch tolerance. Adding water to a concrete mix designed for a lower slump does not meet these recommendations.

It should also be noted that the subsurface materials encountered in our borings generally consisted of hard to very hard Maristone. Thus, we anticipate that high-torque drilling equipment will be required for pier installation at this site. The Contractor should be familiar with and prepared for such conditions.

Closing Unless stated otherwise, all other previous recommendations provided in our Geotechnical Engineering Study Report dated May 29, 2019 and revised on July 3, 2019 that are not specifically addressed in this Letter should be followed. Please feel free to call with questions or comments.

Please contact us with any questions or if additional information is needed.

Sincerely, Arias & Associates, Inc.

TBPE Registration No: F-32

~hep’~erd,.E.,D.GE Senior Geotechnical Engineer Supplemental Letter #3 Arias Geoprofessionals

Kacy . Crawford, P.E.

Geotechnical Engineer

10/8/2020 •.~... ••••••• ••

JERRY D. SHEPHERD

112142

Arias Job No. 2018-933

Arias Geoprofessionals A-1 Arias Job No. 2018-933

APPENDIX A: FIGURES

142 Chula Vista, San Antonio, Texas 78232 Phone: (210) 308-5884 • Fax: (210) 308-5886

VICINITY MAP

USDA ARS KBUSLIRL

Cattle Working Barn: B-15 Kerrville, Texas

Date: May 20, 2019 Job No.: 2018-933 Figure 1

Drawn By: RWL Checked By: JDS Approved By: CMS Scale: N.T.S.

Approximate Site Limits

142 Chula Vista, San Antonio, Texas 78232 Phone: (210) 308-5884 • Fax: (210) 308-5886

BORING LOCATION PLAN

USDA ARS KBUSLIRL

Cattle Working Barn: B-15

Kerrville, Texas

Date: October 8, 2020 Job No.: 2018-933 REVISIONS: Drawn By: RWL Checked By: JDS No.: Date: Description: Approved By: CMS Scale: N.T.S.

Figure 2 1 of 1 D

IS

C

LA

IM

E R

T hi s dr aw in g is f or il lu st ra tio n on ly a nd s ho ul d no t be u se d fo r de si gn o r co ns tr uc tio n pu rp os es

A ll lo ca tio ns a re a pp ro xi m at e.

Arias Geoprofessionals B-1 Arias Job No. 2018-933

APPENDIX B: BORING LOGS AND SYMBOL KEY SHEET

SANDY LEAN CLAY (CL), very stiff, gray and light brown

STRATUM II

MARLSTONE, very hard, gray, highly weathered, marly, with clay filled voids.

STRATUM III

FILLED VOID: Lean Clay with Sand (CL), light gray and tan, from 4 feet to 8 feet

MARLSTONE, continued from above, STRATUM III.

**50/5"

**50/3"

**50/1"

**50/1"

**50/1"

**50/1"

**50/4"

SS

SS

SS

SS

SS

SS

SS

SS

SS

SS

Location: Cattle Working Barn: See Boring Location Plan

Coordinates: N30o4'23.16'' W99o6'41.51''

WC = Water Content (%) PL = Plastic Limit LL = Liquid Limit PI = Plasticity Index N = SPT Blow Count

** = Blow Counts During Seating Penetration

-200 = % Passing #200 Sieve

Soil Description

Nomenclature Used on Boring LogGroundwater Data:

During drilling: Not encountered

Field Drilling Data:

Coordinates: Hand-held GPS Unit Logged By: L. Arizola Driller: Eagle Drilling, Inc.

Equipment: Truck-mounted drill rig

Single flight auger: 0 - 35 ft

Backfill: Cuttings

(continued)

Split Spoon (SS)

Job No.: 2018-933

Project: USDA ARS KBUSLIRL Kerrville, Texas

Sampling Date: 9/15/20

Arias Geoprofessionals

Boring Log No. B-15

-9

.G

P J

/5

/2

(B O

R

IN

G L

O G

S A

-0

2, A

R

IA

S S

A

-0 1.

G D

T ,L

IB

R

A R

Y

-0

1.

G

LB

-200NPL LL PIWCSNDepth (ft)

MARLSTONE, continued from above, STRATUM III. (continued)

Borehole terminated at 35 feet

**50/3"11SS

Location: Cattle Working Barn: See Boring Location Plan

Coordinates: N30o4'23.16'' W99o6'41.51''

WC = Water Content (%) PL = Plastic Limit LL = Liquid Limit PI = Plasticity Index N = SPT Blow Count

** = Blow Counts During Seating Penetration

-200 = % Passing #200 Sieve

Soil Description

Nomenclature Used on Boring LogGroundwater Data:

During drilling: Not encountered

Field Drilling Data:

Coordinates: Hand-held GPS Unit Logged By: L. Arizola Driller: Eagle Drilling, Inc.

Equipment: Truck-mounted drill rig

Single flight auger: 0 - 35 ft

Backfill: Cuttings

Split Spoon (SS)

Job No.: 2018-933

Project: USDA ARS KBUSLIRL Kerrville, Texas

Sampling Date: 9/15/20

Arias Geoprofessionals

Boring Log No. B-15 (continued)

-9

.G

P J

/5

/2

(B O

R

IN

G L

O G

S A

-0

2, A

R

IA

S S

A

-0 1.

G D

T ,L

IB

R

A R

Y

-0

1.

G

LB

-200NPL LL PIWCSNDepth (ft)

GW

GP

GM

GC

SW

SP

SM

SC

ML

CL

MH

CH

Massive or Weakly Bedded Limestones

M o re t h a n h a lf o f m a te ri a l S

M A

L L E

R th a n N o S ie v e s iz e

F O

R M

A T

IO

N

A L

M A

T E

R

IA

L S

GROUP

SYMBOLS

KEY TO TERMS AND SYMBOLS USED ON BORING LOGS

C O

A R

S E

-G R

A

IN

E D

S O

IL

S

G R

A V

E L

S S

A N

D S

M o re t h a n H a lf o f C o a rs e f ra c ti o n i s

L A

R G

E R t h a n N o S ie v e s iz e

M o re t h a n h a lf o f m a te ri a l L A

R G

E R t h a n N o S ie v e s iz e

MAJOR DIVISIONS

Silty Gravels, Gravel-Sand-Silt Mixtures

Poorly-Graded Gravels, Gravel-Sand Mixtures, Little or no Fines

Well-Graded Gravels, Gravel-Sand Mixtures, Little or no Fines

DESCRIPTIONS

Clayey Sands, Sand-Clay Mixtures

Silty Sands, Sand-Silt Mixtures

Poorly-Graded Sands, Gravelly Sands, Little or no Fines

Well-Graded Sands, Gravelly Sands, Little or no Fines C le a n G ra v e ls

(l it tl e o r n o F in e s

G ra v e ls w h

F in

(A p p re c ia b le m o u n t o f F in e s

C le a n S a n d

(l tl e o r n o F in e s

S a n d s w it h F in

(A p p re c ia b le m o u n t o f F in e s

L iq u id

L im it l e th n

L iq u id

L im g re a te r th a n

LIMESTONE

MARLSTONE

SANDSTONE

Clayey Gravels, Gravel-Sand-Clay Mixtures

Massive Sandstones, Sandstones with Gravel Clasts

Inorganic Clays of High Plasticity, Fat Clays

Inorganic Silts, Micaceous or Diatomaceous Fine Sand or Silty Soils, Elastic Silts

Inorganic Clays of Low to Medium Plasticity, Gravelly Clays, Sandy Clays, Silty Clays, Lean Clays

Inorganic Silts & Very Fine Sands, Rock Flour, Silty or Clayey Fine Sands or Clayey Silts with Slight

Plasticity

Indurated Argillaceous Limestones

Indicates Final Observed Groundwater Level

Indicates Initial Observed Groundwater Location

Cretaceous Clay Deposits

Massive or Poorly Bedded Chalk Deposits

Mudstone or Massive Claystones

F

IN

E -G

R A

IN

E

D S

O

IL

S

M o re t h a n h a lf o f C o a rs e f ra c ti o n i

S M

A L L E

R t h a n N o S ie v e s iz e

S

IL

T

C

A Y

S

S

IL

T

C

A Y

S

GROUNDWATER

MARINE CLAYS

CHALK

CLAYSTONE

Very Dense

30 - 50

Over 50

10 - 30

Consistency and Strength of Cohesive Soils

Number of Blows per ft., N

Unconfined

Compressive

Strength, qᵤ (tsf)

Consistency

Density of Granular Soils

Relative Density

Very Loose

Number of

Blows per ft., N

0 - 4

4 - 10 Loose

Medium

Dense

Below 2

2 - 4 Soft

Very Soft

Stiff

Less than 0.25

0.25 - 0.5

0.5 - 1.0

1.0 - 2.0

Medium (Firm)

Very Stiff

Hard

4 - 8

8 - 15

15 - 30

Over 30 Over 4.0

2.0 - 4.0

Arias Geoprofessionals

Group

Symbol

GW

(Less than 5% fines C

Cu < 4 and/or GP

[Cc < 1 or Cc > 3] D

Gravels with Fines GM

(More than 12% fines C

GC

Sands Clean Sands SW

(Less than 5% fines H

) Cu < 6 and/or SP

[Cc < 1 or Cc > 3] D

Sands with Fines SM

(More than 12% fines H

SC

Silts and Clays inorganic CL

ML

organic OL

Silts and Clays inorganic CH

MH

organic OH

HIGHLY ORGANIC SOILS PT

A Based on the material passing the 3-inch (75mm) sieve B If field sample contained cobbles or boulders, or both, add "with cobbles or boulders, or both" to group name C Gravels with 5% to 12% fines require dual symbols:

GW-GM well-graded gravel with silt

GW-GC well-graded gravel with clay

GP-GM poorly-graded gravel with silt

GP-GC poorly-graded gravel with clay D

Cu = D60/D10 Cc =

E If soil contains ≥ 15% sand, add "with sand" to group name F If fines classify as CL-ML, use dual symbol GC-GM, or SC-SM G If fines are organic, add "with organic fines" to group name H Sand with 5% to 12% fines require dual symbols:

SW-SM well-graded sand with silt

SW-SC well-graded sand with clay

SP-SM poorly-graded sand with silt

SP-SC poorly-graded sand with clay I If soil contains ≥ 15% gravel, add "with gravel" to group name J If Atterberg limits plot in hatched area, soil is a CL-ML, silty clay K If soil contains 15% to < 30% plus No. 200, add "with sand" or "with gravel," whichever is predominant L If soil contains ≥ 30% plus No. 200, predominantly sand, add "sandy" to group name M If soil contains ≥ 30% plus No. 200, predominantly gravel, add "gravelly" to group name N PI ≥ 4 and plots on or above "A" line O PI < 4 or plots below "A" line P PI plots on or above "A" line Q PI plots below "A" line

TERMINOLOGY

Boulders Over 12-inches (300mm) Parting Inclusion < 1/8-inch thick extending through samples

Cobbles 12-inches to 3-inches (300mm to 75mm) Seam Inclusion 1/8-inch to 3-inches thick extending through sample

Gravel 3-inches to No. 4 sieve (75mm to 4.75mm) Layer Inclusion > 3-inches thick extending through sample

Sand No. 4 sieve to No. 200 sieve (4.75mm to 0.075mm)

Silt or Clay Passing No. 200 sieve (0.075mm)

Calcareous Containing appreciable quantities of calcium carbonate, generally nodular

Stratified Alternating layers of varying material or color with layers at least 6mm thick

Laminated Alternating layers of varying material or color with the layers less than 6mm thick

Fissured Breaks along definite planes of fracture with little resistance to fracturing

Slickensided Fracture planes appear polished or glossy sometimes striated

Blocky Cohesive soil that can be broken down into small angular lumps which resist further breakdown

Lensed Inclusion of small pockets of different soils, such as small lenses of sand scattered through a mass of clay

Homogeneous Same color and appearance throughout

(D30)

D10 x D60

KEY TO TERMS AND SYMBOLS USED ON BORING LOGS

TABLE 1 Soil Classification Chart (ASTM D 2487-11)

Group Name B

Organic Clay K,L,M,N

Organi Silt K,L,M,O

Fat Clay K,L,M

Clayey Gravel E,F,G

Well-Graded Sand I

Poorly-Graded Sand I

Silty Sand F,G,I

Clayey Sand F,G,I

Well-Graded Gravel E

Poorly-Graded Gravel E

Silty Gravel E,F,G

Soil Classification

Criteria of Assigning Group Symbols and Group Names Using Laboratory Tests A

More than 50% retained on No.

200 sieve

FINE-GRAINED SOILS

COARSE-GRAINED SOILS

Primarily organic matter, dark in color, and organic odor

Liquid limit less than 50

Liquid limit 50 or more

PI > 7 and plots on or above "A" line J

PI < 4 or plots below "A" line J

PI plots on or above "A" line

PI plots on or below "A" line

Fines classify as CL or

CH

(50% or more of coarse fraction passes No. 4 sieve)

50% or more passes the No.

200 sieve

Cu ≥ 4 and 1 ≤ Cc ≤ 3 DGravels Clean Gravels

Elastic Silt K,L,M

Organic Clay K,L,M,P

Organic Silt K,L,M,Q

Peat

Lean Clay K,L,M

Silt K,L,M

Fines classify as CL or

CH

Cu ≥ 6 and 1 ≤ Cc ≤ 3 D

Fines classify as ML or

MH

(More than 50% of coarse fraction retained on No. 4 sieve)

Fines classify as ML or

MH

<0.75

<0.75

Liquid limit - oven dried

Liquid limit - not dried

Liquid limit - oven dried

Liquid limit - not dried

Excellent

Rock Mass QualityVelocity IndexRQD %

90 – 100

75 – 90

50 – 75

25 – 50

0 – 25

0.80 – 1.00

0.60 – 0.80

0.40 – 0.60

0.20 – 0.40

0 – 0.20

Good

Fair

Very Poor

Poor

Very widely (fractured or jointed)

Widely

Medium

Closely

Very closely

Descriptions for Joints, Faults, or Other Fractures

Extremely close

Diagnostic Features

No visible sign of Decomposition or discoloration. Rings under hammer impact.

Slight discoloration inwards from open fractures, otherwise similar to F.

Discoloration throughout. Weaker minerals such as feldspar decomposed. Strength somewhat less than fresh rock, but cores cannot be broken by hand or scraped by knife. Texture preserved.

Most minerals somewhat decomposed. Specimens can be broken by hand with effort or shaved with knife. Core stones present in rock mass. Texture becoming indistinct, but fabric preserved.

Minerals decomposed to soil, but fabric and structure preserved (Saprolite). Specimens easily crumbled or penetrated.

Advanced state of decomposition resulting in plastic soils. Rock fabric and structure completely destroyed. Large volume change.

Spacing Description for Joints, Faults or Other Fractures

Thickly

Medium

Thinly

Very thinly

Description for Micro-Structural

Features: Lamination, Foliation, or

Cleavage

Intensely (laminated, foliated, or cleaved)

Very intensely

Spacing

¼ – ¾ inch

2 – 6 feet

Description for Structural Features:

Bedding, Foliation, or Flow Banding

Very thickly (bedded, foliated, or banded)

Symbol

F

WS

WM

WH

WC

RS

More than 6 feet

Engineering Classification for in Situ Rock Quality

Class

I

II

III

IV

V

Extremely hard

Hardness

Very hard

Hard

Soft

Very soft

Less than ¼ inch

¾ – 2½ inches

2½ – 8 inches

8 – 24 inches

Grade

Fresh

Slightly Weathered

Moderately Weathered

Highly Weathered

Completely Weathered

KEY TO TERMS AND SYMBOLS USED ON BORING LOGS

Hardness Classification of Intact Rock

Rock Weathering Classifications

Rock Discontinuity Spacing

Residual Soil

> 2,000

Approximate Range of Uniaxial

Compression Strength kg/cm²

(tons/ft²)

2,000 – 1,000

1,000 – 500

500 – 250

250 – 10

Field Test

Many blows with geologic hammer required to break intact specimen.

Hand held specimen breaks with hammer end of pick under more than one blow.

Cannot be scraped or pealed with knife, hand held specimen can be broken with single moderate blow with pick.

Can just be scraped or peeled with knife. Indentations 1mm to 3mm show in specimen with moderate blow with pick.

Material crumbles under moderate blow with sharp end of pick and can be peeled with a knife, but is too hard to hand-trim for triaxial test specimen.