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Environmental • Construction Materials Testing • Geotechnical • Subsurface Investigations



104 Rock Bridge RoadDothan, FL

Madison Dothan, LLC Preliminary Report of Subsurface

Investigation and Geotechnical Evaluation SESI Project No: P18-0351

October 22, 2018

Madison Dothan, LLC Page 2

SITE AND PROJECT INFORMATION The proposed project site is located at 104 Rock Bridge Road in Dothan, Alabama (Houston County Parcel ID: 380902102000016.023). At the time of this investigation, a single-story commercial type structure with associated paved areas was situated on site. It is understood that this structure will be demolished prior to construction of the proposed project. We understand the proposed structure will be a one-story, metal-framed structure with a brick veneer skirt and wainscoting exterior. Shallow foundations are anticipated. The proposed structure has a footprint area of approximately 10,500 square feet. Topographic information was provided on October 8th, 2018, which indicated that the proposed finished floor elevation (FFE) will be at +279.1’, requiring up to 4 feet of cut and 4 feet of fill to achieve proposed grade. At this time, structural information was not provided; however, we have assumed loads up to 10 kips and 2.5 klf for column and wall loads, respectively.

FIELD INVESTIGATIVE PROCEDURES On September 18th, 2018, personnel with our firm traveled to the project site and completed the field testing for the above referenced project. For our geotechnical investigation, five (5) cone penetration test (CPT) soundings were performed to a depth of approximately 30 feet below the existing ground surface. At test locations C-1, C-3 and C-4, direct push borings were performed to depths ranging from 10 to 15 feet below the existing ground surfaces. See the attached Figure 1 and Figure 2 for our approximate test locations. The cone penetrometer is track mounted and rather than sampling and testing at five-foot intervals, as normally done with standard penetration borings, the cone penetrometer is an electronic device that provides continuous evaluation of the soils bearing capacity through point and frictional resistances. The cone penetrometer is hydraulically pushed into the soil with point and frictional resistances obtained continuously on a computer printout. This testing equipment provides an accurate definition of the soil strength characteristics and the changes in stratification. Cone soundings were performed in general accordance with ASTM D5778. The direct push borings were performed with our Geoprobe 6622 and the DT22 soil sampling system. This is a closed-piston sampler, with an inner piston rod and outer drive casing, and is driven to the top of the sampling interval. The inner piston rod is removed, and the sampler is driven to collect a soil sample. The soil samples are collected in a clear 5-foot PVC liner and are delivered back to our laboratory for soil classifications and laboratory testing.


LABORATORY TESTING PROCEDURES Laboratory investigative work consisted of physical examination of samples obtained during the soil test boring operation. Soil samples were visually classified in the laboratory in accordance with the Unified Soil Classification System. Evaluation of these samples, in conjunction with cone penetration resistances, have been used to estimate soil characteristics. Natural Moisture: Seven (7) samples were selected for determination of their natural moisture content. In the laboratory, the samples were weighed, dried, and their moisture content was calculated in general accordance with ASTM D2216. Percent Passing 200 Mesh Sieve: Seven (7) samples were selected to determine the percent of materials, by dry weight, finer than the U.S. Number 200 Mesh Sieve. This test was performed in general accordance with ASTM D1140.

Atterberg Limits: Two (2) samples were selected to determine their plasticity in accordance with AASHTO T89 & T90. The laboratory test results are shown on the boring logs at the depth of the tested sample. Abbreviations of laboratory data are shown below: NM = Natural Moisture Content (%) -200 = Percent Finer than the U.S. No. 200 Mesh Sieve

LL = Liquid Limit (%) PI = Plasticity Index

CONE SOUNDINGS The CPT Logs graphically indicate the cone tip resistance, friction ratio, equivalent N-value and interpreted soil type at each sounding location. Soil classifications and data were interpreted from methods recommended by Robertson and Campanella and/or the Swedish Geotechnical Institute Information Publication No. 15E. Correlations between Cone Resistance values and Standard Penetration Testing “N” values were performed according to the methods developed by Robertson, Campanella and Wightman. The soil types and stratigraphy shown on the CPT Log sheets are based upon material parameters measured and evaluated as the cone is advanced. The CPT Log sheets were developed for general information only.


SOIL CONDITIONS

The Log of Boring and CPT Log sheets attached provide a detailed description of the site soils. Beneath a thin layer of asphalt or slightly clayey sands, clayey sands to highly plastic fat clays were encountered to the depths of termination. The highly plastic clays were encountered as shallow as about 1.5 feet below existing grade (location C-4) and ranged in relative density from medium stiff to hard.

Note: Highly plastic clays were encountered at various depths throughout the site.

These soils are highly unsuitable for typical construction activities due to their shrinking/swelling properties with changes in moisture. According to our laboratory testing, the soils encountered throughout the site were typically very dry.

Groundwater was not encountered within the depths of the borings/soundings

performed. Fluctuations in the water table depths will occur due to changes in gradient, seasonal precipitation/evapotranspiration differences, and tidal influence. Therefore, it is recommended that the groundwater levels be verified prior to any excavations on the site.

FOUNDATION CONSIDERATIONS / ANALYSIS

As mentioned above, highly plastic fat clays were encountered at various depths throughout most of the project site. These soils are considered unsuitable for construction of a conventional slab-on-grade shallow foundation system when present in close proximity to foundation elements due to their potential for high volume change (shrink/swell) with changes in moisture content. Due to the moisture state of these soils at the time of this investigation, it is highly likely that these soils will see some volume change due to swelling throughout the construction process. The most commonly used methods for dealing with these conditions are:

1.) Over-excavate the highly plastic clays below the depth to constant moisture and

replace them with low permeability structural fill. Typical shallow foundation designs would then be considered acceptable for construction of structures.

2.) Utilize a stiffened post-tensioned slab or grade-beam reinforced waffle slab, which

would assist with limiting differential movement from settlement or shrinking/swelling of subsurface soils.

Generally, the subsurface soils with swelling potential above the ground water level and within the depths subjected to moisture content changes are expected to undergo volume change behavior and were considered in our potential vertical rise (PVR) estimation. The potential vertical rise (PVR) is estimated to be on the order of 2 inches using an applied load of 1.0 psi


(utilizing the conditions at sounding/direct push boring C-4). The PVR estimates were performed using the TEX 124E method analyzing the upper 10 feet of soil. One (1) inch of PVR is generally accepted as the maximum allowable value for design and construction. However, the Structural Engineer or others should determine if these PVR values are within the acceptable limits.

FOUNDATION RECOMMENDATIONS Our evaluation of foundation conditions has been based on structural information

presented in this report and subsurface data obtained during our investigation. In evaluating soil test borings, we have used correlations previously made between penetration resistances and foundation stabilities observed in soil conditions similar to those encountered at this site.

Method 1 (Over-Excavation)

If the over-excavation alternative is chosen, we recommend over-excavating the highly

plastic clay materials to a depth of at least 6 feet below the bottom of the floor slab. This depth of over-excavation and replacement with cohesive structural fill material was estimated to bring the PVR value below 1 inch if proper site preparations are performed. We recommend beginning the over-excavation process in the southwestern portion of the project site and continue to over-excavate moving laterally throughout the proposed structure’s footprint and a minimum of 5 feet beyond the building perimeter. Due to the limited number of borings performed within the building area, SESI cannot estimate the amount of over-excavation that would be required. We recommend the owner hire SESI to witness over-excavation of these materials, as depths of over-excavation will vary laterally between boring locations.

If these soils are over-excavated and replaced per SESI’s recommendations, the

structure may be supported by a conventionally or monolithically designed shallow foundation system using an allowable soil bearing pressure of 2,000 psf. Maximum settlement due to structural loading below 1.0 inch is anticipated. Maximum differential settlements due to structural loading are expected to be less than 0.5 inches. We recommend that all footings bear a minimum of 18 inches below outside finished grade with minimum footing widths of 18 inches and 30 inches, respectively, for continuous and isolated footings. The site preparation recommendations stated below apply to this alternative.


Method 2 (Post-Tensioned Slab)

If the post-tensioned slab system is implemented per SESI’s recommendations, the structure may be supported by a shallow foundation system using an allowable soil bearing pressure of 2,000 psf. Maximum settlement due to structural loading of less than 1.0 inch is anticipated. Maximum differential settlements due to structural loading are expected to be less than 0.5 inches. We recommend that all footings bear a minimum of 18 inches below outside finished grade with minimum footing widths of 18 inches and 30 inches, respectively, for continuous and isolated footings. Post-Tensioned Slab Design Parameters are provided below. The site preparation recommendations stated below apply to this alternative.

Note: This alternative does not reduce the potential vertical rise (PVR) within the

building area. Instead, post-tensioning is a method of stiffening the slab/foundation system to withstand this magnitude of movement without failing structurally. The structural engineer should be consulted to determine if a maximum of 2 inches of PVR is acceptable.

Site Preparation Recommendations

We recommend the following site/soil preparation procedures prior to foundation

construction: 1.) Clear and grub the surface soils within the proposed building area extending at

least 5 feet beyond the building perimeter to remove all topsoil, organics, and other deleterious materials. Perform the required cut/excavation as required for proposed grading purposes. Note: Due to the existing structure being demolished, we anticipate utility trenches to be within the proposed project area. These utilities should be abandoned, and former trenches be backfilled and properly compacted, as necessary.

2.) Proof-roll the stripped / excavated surface to identify any soft or yielding areas

that may require additional over-excavation. 3.) If fill is required to achieve proposed grades, we recommend they consist of

clayey sands that contain a minimum of 25%, by dry weight, finer than the U.S. No. 200 mesh sieve. All fill should be placed in thin level lifts not to exceed 8 inches (loose) and compacted to a density of 95% of the Modified Proctor maximum dry density throughout its full depth.


4.) Laboratory moisture-density relationships (Proctors) and in-place density (compaction) tests should be performed to verify compliance with the aforementioned compaction recommendations. We recommend performing one compaction test:

- in each isolated column footing - per 75 lineal feet of continuous footing - per 2,500 sf of building area per foot of backfill

The bottom of the foundation excavations must be dry, clean, and free of loose materials / construction debris prior to placement of steel or concrete. It should be observed by SESI’s Geotechnical Engineer or his representative prior to steel or concrete placement. Concrete shall be poured as quickly as possible to avoid exposure of the footing materials to moisture changes (wetting or drying). Surface run-off water should be channeled away from the excavations and not be allowed to pond. If for any reason the excavation is required to be open for more than one (1) day, it shall be protected to minimize moisture loss/gain.

POST-TENSIONED SLAB DESIGN PARAMETERS The soil parameters for the design of PT waffle slab are as follows:

1. Differential Soil Movement:

Differential Soil Movement

Existing Soil Conditions

ym center (inches) 1.11 ym edge (inches) 1.02

2. Edge Moisture Variation:

Edge Moisture

Variation Existing Soil Conditions

em center (feet) 3.5 em edge (feet) 5.1

These parameters were calculated following the procedures of the PTI Design of Post-Tensioned Slabs-on-Ground, 3rd Edition (2008). They are based on correlations established with the results of the tests performed at the time of the original subsurface investigation. When specific data was not available, the most conservative values were assumed.


HIGHLY PLASTIC CLAY MAINTENANCE

Due to the moisture state of the soils encountered at the project site during the investigation, the on-site soils are considered very sensitive to moisture variations which could lead to high swelling over time, thus, causing undesirable foundation shifts. We caution that any additional moisture (i.e. rain, sprinkler systems, pressure washers, etc.) could cause these highly plastic clays to swell. Any additional moisture should be very limited within the project site throughout construction.

Water should be kept from ponding adjacent to and beneath the structure at all times in order to prevent reductions of the soil strength and support capabilities. For this, the following measures should be implemented:

a) Surface Drainage – always drain away from the foundation; on vegetated

ground, a minimum slope of 5% is recommended. Never allow water to accumulate close to or around the foundations. Yard drains should be placed and tied-in to the roof or storm drainage systems in areas where sufficient slope cannot be attained.

b) Landscaping: • Avoid placing plants immediately adjacent to the foundation. • Avoid placing sprinkler system pipes near the foundation (they could leak). • Direct sprinkler heads away from the foundation.

Trees should be planted at a minimum distance of half the anticipated canopy diameter or twenty (20) feet, whichever is larger, from the foundation edge.

Floor Slab Precautions

The precautions listed below are for informational purposes for the construction of slab-

on-grade pads. These details will not reduce the amount of movement but are intended to reduce potential damage should some settlement of the supporting subgrade take place. Some increase in moisture content is inevitable because of development and associated landscaping. However, extreme moisture content increases can be largely controlled by proper and responsible site drainage, building maintenance and irrigation practices.

• Cracking of slab-on-grade concrete is normal and should be expected. Cracking can

occur not only as a result of heaving or compression of the supporting soil material, but also as a result of concrete curing stresses. The occurrence of concrete shrinkage cracks and problems associated with concrete curing may be reduced and/or controlled by limiting the slump of the concrete, proper concrete placement, finishing and curing, and by the placement of crack control joints at frequent intervals, particularly where re-entrant slab corners occur. The American Concrete Institute (ACI) recommends a maximum panel size (in feet) equal to approximately three times the thickness of the


slab (in inches) in both directions for typical slabs-on-grade. For example, joints are recommended at a maximum spacing of twelve (12) feet based on having a four-inch slab. Using fiber reinforcement in the concrete can also control shrinkage cracking.

• Areas supporting slabs should be properly moisture conditioned and compacted.Backfill placed in all interior and exterior water/sewer line trenches should be carefullycompacted to reduce the shear stress in the concrete spanning over these areas.

COHESIVE SOILS NOTES

We caution that the majority of the site soils are cohesive and therefore are sensitive to changes in moisture content. Excess moisture in these soils will cause difficulty achieving compaction which could delay construction operations. Therefore, we recommend that construction activities be planned such that these soils are exposed for the least possible time. We also recommend that positive drainage be maintained throughout the jobsite. A good construction practice would be to “seal” any soils loosened during the day’s work by rolling with a rubber-tired or flat-wheel steel roller at the end of each work day. Also, as soon as possible after a rainfall event, all standing water should be removed from the construction area.

If the soils are (or become) too wet to compact, they may be aerated to reduce the moisture content. It has been our experience that placing materials in thinner lifts (no more than 8 inches loose) and compacting with kneading-type equipment has proven to be most effective for compaction of cohesive soils.

ADDITIONAL TESTING

To better define the extent of the highly plastic clays beneath the proposed building area, we recommend that additional soil test borings be performed after demolition of the existing structure. The results of these borings may be used to refine the conclusions and recommendations contained in this report.

The effectiveness of the foundations will depend significantly on the proper preparation of the soils, as indicated previously. Therefore, we recommend Southern Earth Sciences, Inc., be employed as the testing laboratory to perform construction testing services. If we are not employed to provide construction testing services, Southern Earth Sciences, Inc., cannot accept any responsibility for any conditions, which deviate from those described in this geotechnical report. Southern Earth Sciences, Inc., should be invited to the pre-construction conference to


discuss the project with all interested parties so that the project may be completed expeditiously and to the intent of our geotechnical report. We would be pleased to review the plans and specifications as they relate to the soil preparation and provide a fee proposal for construction testing.

GENERAL COMMENTS

Professional judgments on design criteria are presented in this letter. These are based partly on our evaluations of technical information provided, partly on our understanding of the characteristics of the project being planned, and partly on our general experience with subsurface conditions in the area. We do not guarantee performance of the project in any respect, only that our judgments meet the standard of care of our profession. This information is exclusively for the use and benefit of the addressee(s) identified on the first page of this report and is not for the use or benefit of, nor may it be relied upon by any other person or entity. The contents of this letter may not be quoted in whole or in part or distributed to any person or entity other than the addressee(s) hereof without, in each case, the advance written consent of the undersigned.

This report has been prepared in order to aid in the evaluation of this property and to assist the architects and engineers in the foundation design. It is intended for use with regard to the specific project discussed herein, and any substantial changes in the buildings, loads, locations, or assumed (or reported) grades shall be brought to our attention immediately so that we may determine how such changes may affect our conclusions and recommendations. We would appreciate the opportunity to review the plans and specifications for the foundation and floor construction to verify that our conclusions and recommendations are interpreted correctly. While the borings performed for this project are representative of subsurface soil conditions at their respective locations and for their respective vertical reaches, local variations of the subsurface materials are anticipated and may be encountered. The boring logs and related information are based on the driller’s logs and visual examination of selected samples in the laboratory. Delineation between soil types shown on the boring logs is approximate, and soil descriptions represent our interpretation of subsurface conditions at the designated boring location on the date drilled.

END OF REPORT

Southern Earth Sciences Inc.Operator: Jamison ShortSounding: C-1Cone Used: DSG1116

CPT Date/Time: 9/18/2018 11:33:43 AMLocation: 104 Rock Bridge RoadJob Number: P18-0351

Maximum Depth = 15.88 feet Depth Increment = 0.066 feet

Auto Enhance On Filter OnCenter*Soil behavior type and SPT based on data from UBC-1983

Tip Resistance

Qt TSF3000

0

2

4

6

8

10

12

14

16

Depth(ft)

Local Friction

Fs TSF60

Pore Pressure

Pw PSI25-5

Friction Ratio

Fs/Qt (%) 80

Soil Behavior Type*

Zone: UBC-1983

1 sensitive fine grained 2 organic material 3 clay

4 silty clay to clay 5 clayey silt to silty clay 6 sandy silt to clayey silt

7 silty sand to sandy silt 8 sand to silty sand 9 sand

10 gravelly sand to sand 11 very stiff fine grained (*) 12 sand to clayey sand (*)

120

SPT N*

60% Hammer1400


CPT Date/Time: 9/18/2018 12:18:10 PMLocation: 104 Rock Bridge RoadJob Number: P18-0351



Tip Resistance

Qt TSF3000

0

5

10

15

20

25

30

35

Depth(ft)

Local Friction

Fs TSF60

Pore Pressure

Pw PSI60-10

Friction Ratio

Fs/Qt (%) 100

Soil Behavior Type*

Zone: UBC-1983





120

SPT N*

60% Hammer1200





Tip Resistance

Qt TSF2500

0

5

10

15

20

25

30

Depth(ft)

Local Friction

Fs TSF90

Pore Pressure

Pw PSI40-5

Friction Ratio

Fs/Qt (%) 90

Soil Behavior Type*

Zone: UBC-1983





120

SPT N*

60% Hammer1600





Tip Resistance

Qt TSF3000

0

5

10

15

20

25

30

Depth(ft)

Local Friction

Fs TSF50

Pore Pressure

Pw PSI50-10

Friction Ratio

Fs/Qt (%) 90

Soil Behavior Type*

Zone: UBC-1983





120

SPT N*

60% Hammer11010


CPT Date/Time: 9/18/2018 11:02:28 AMLocation: 104 Rock Bridge RoadJob Number: P18-0351



Tip Resistance

Qt TSF5000

0

5

10

15

20

25

30

35

Depth(ft)

Local Friction

Fs TSF60

Pore Pressure

Pw PSI35-5

Friction Ratio

Fs/Qt (%) 100

Soil Behavior Type*

Zone: UBC-1983





120

SPT N*

60% Hammer1200

40

23

72

SP-SCSC

SC

CH

16

11

24

Brown Slightly Clayey Fine SAND withOrganicsTan Clayey Fine SAND

Red, Light Grey, and Tan Clayey FineSAND

Light Grey and Red Highly Plastic FatCLAY

0

1

2

3

4

5

6

7

8

9

10

11

12

LL

N Value(blows/ft)

20 40 60 80

Page 1 of 1LOG OF BORING C-1104 Rock Bridge Road

Dothan, AL

P18-0351

09/18/18

SPT Shelby Tube

Notes:

PROJECT:

LOCATION:

PROJECT NO.:

DATE:

METHOD:

DRILLER:

ENGR / GEOL:

SURFACE ELEVATION:

Direct Push

JS

RCT+272'

Per Plan

Water Level

NA

TU

RA

L M

OIS

TU

RE

(%)

PA

SS

ING

#20

0 S

IEV

E(%

)Soil SymbolsSampler Symbols

and Field Test Data

Water Observations: Groundwater Not Encountered

Elevation /Depth

PL PI

ATTERBERGLIMITS (%)

LIQ

UID

LIM

IT

PLA

ST

IC L

IMIT

PLA

ST

ICIT

YIN

DE

X

MATERIAL DESCRIPTION

LOCATION

USCS

N - SPT Data (Blows/Ft) P - Pocket Penetrometer (tsf)

Sample Key:

PL LLMC

20 40 60 80Atterberg LimitsNatural Moisture

Measured: Perched:Est. Seasonal High GWL:

LOG

OF

BO

RIN

G P

18-0

285.

GP

J S

ES

PC

FL.

GD

T 1

0/4

/18

43

61

SCSC

SC

CH

SC

CH

16

21

ASPHALTRed Clayey Fine SANDTan and Brown Clayey Fine SAND

Tan, Light Grey, and Red Clayey Fine SAND

Light Grey and Red Sandy Highly Plastic CLAY

Tan and Red Clayey Fine SAND

Light Grey and Red Highly PlasticCLAY

0

5

10

15

LL

N Value(blows/ft)

20 40 60 80


Dothan, AL

P18-0351

09/18/18

SPT Shelby Tube

Notes:

PROJECT:

LOCATION:

PROJECT NO.:

DATE:

METHOD:

DRILLER:

ENGR / GEOL:

SURFACE ELEVATION:

Direct Push

JS

RCT+280'

Per Plan

Water Level

NA

TU

RA

L M

OIS

TU

RE

(%)

PA

SS

ING

#20

0 S

IEV

E(%


and Field Test Data


Elevation /Depth

PL PI

ATTERBERGLIMITS (%)

LIQ

UID

LIM

IT

PLA

ST

IC L

IMIT

PLA

ST

ICIT

YIN

DE

X


LOCATION

USCS


Sample Key:

PL LLMC



LOG

OF

BO

RIN

G P

18-0

285.

GP

J S

ES

PC

FL.

GD

T 1

0/4

/18

65

91

SCSC

CH

CH

CH

35

63

57

92

22

29

22

29

ASPHALTRed Clayey Fine SANDTan Clayey Fine SAND

Light Tan Sandy Fat CLAY

Light Grey and Red Highly Plastic Sandy Fat CLAY

Pink and Light Grey Highly Plastic Fat CLAY

0

1

2

3

4

5

6

7

8

9

10

11

12

LL

N Value(blows/ft)

20 40 60 80


Dothan, AL

P18-0351

09/18/18

SPT Shelby Tube

Notes:

PROJECT:

LOCATION:

PROJECT NO.:

DATE:

METHOD:

DRILLER:

ENGR / GEOL:

SURFACE ELEVATION:

Direct Push

JS

RCT+278'

Per Plan

Water Level

NA

TU

RA

L M

OIS

TU

RE

(%)

PA

SS

ING

#20

0 S

IEV

E(%


and Field Test Data


Elevation /Depth

PL PI

ATTERBERGLIMITS (%)

LIQ

UID

LIM

IT

PLA

ST

IC L

IMIT

PLA

ST

ICIT

YIN

DE

X


LOCATION

USCS


Sample Key:

PL LLMC



LOG

OF

BO

RIN

G P

18-0

285.

GP

J S

ES

PC

FL.

GD

T 1

0/4

/18

APPENDIX

DRILLING AND PENETRATION TESTING PROCEDURES

The borings were advanced with a 4‐inch continuous flight auger, hollow stem auger or by a mud rotary drilling process. At regular intervals, the drilling tools were withdrawn and soil samples obtained with a standard 1.4‐inch I.D., 2.0‐inch O.D., split‐tube sampler. The sampler was initially seated six inches to penetrate loose cuttings, then driven an additional foot with blows of a 140 pound hammer falling 30 inches. The number of hammer blows required to drive the sampler the final foot was recorded and is designated the “penetration resistance”. Penetration resistance is an index to the soil strength and density which may be evaluated in engineering design. The samples were visually classified in the field by the driller as they were obtained. Representative portions of each soil sample were then sealed in plastic bags and transported to our laboratory where they were examined by an Engineer or Geologist to verify the field classifications.

ENGINEERING CLASSIFICATION

COHESIONLESS SOILS (SANDS)

DESCRIPTION BLOW COUNT “N” VERY LOOSE 0 TO 4

LOOSE 4 TO 10 MEDIUM DENSE 10 TO 30

DENSE 30 TO 50 VERY DENSE 50 TO 100

COHESIVE SOILS (CLAYS)

DESCRIPTION UNCONFINED COMPRESSIVE

STRENGTH, qu, tsf

BLOW COUNT “N”

VERY SOFT <1/4 0 TO 2

SOFT ¼ TO ½ 2 TO 4

MEDIUM STIFF ½ TO 1 4 TO 8

STIFF 1 TO 2 8 TO 15

VERY STIFF 2 TO 4 15 TO 30

HARD >4 >30

N = Number of blows for each foot of penetration into soil; 2” O.D. split spoon sampler

driven by 140 pound hammer dropping 30 inches.

Geotechnical Services Are Performed forSpecific Purposes, Persons, and ProjectsGeotechnical engineers structure their services to meet the specific needs oftheir clients. A geotechnical engineering study conducted for a civil engi-neer may not fulfill the needs of a construction contractor or even anothercivil engineer. Because each geotechnical engineering study is unique, eachgeotechnical engineering report is unique, prepared solely for the client. Noone except you should rely on your geotechnical engineering report withoutfirst conferring with the geotechnical engineer who prepared it. And no one— not even you — should apply the report for any purpose or projectexcept the one originally contemplated.

Read the Full ReportSerious problems have occurred because those relying on a geotechnicalengineering report did not read it all. Do not rely on an executive summary.Do not read selected elements only.

A Geotechnical Engineering Report Is Based on A Unique Set of Project-Specific FactorsGeotechnical engineers consider a number of unique, project-specific fac-tors when establishing the scope of a study. Typical factors include: theclient's goals, objectives, and risk management preferences; the generalnature of the structure involved, its size, and configuration; the location ofthe structure on the site; and other planned or existing site improvements,such as access roads, parking lots, and underground utilities. Unless thegeotechnical engineer who conducted the study specifically indicates oth-erwise, do not rely on a geotechnical engineering report that was:• not prepared for you,• not prepared for your project,• not prepared for the specific site explored, or• completed before important project changes were made.

Typical changes that can erode the reliability of an existing geotechnicalengineering report include those that affect: • the function of the proposed structure, as when it's changed from a

parking garage to an office building, or from a light industrial plant to a refrigerated warehouse,

• elevation, configuration, location, orientation, or weight of the proposed structure,

• composition of the design team, or• project ownership.

As a general rule, always inform your geotechnical engineer of projectchanges—even minor ones—and request an assessment of their impact.Geotechnical engineers cannot accept responsibility or liability for problemsthat occur because their reports do not consider developments of whichthey were not informed.

Subsurface Conditions Can ChangeA geotechnical engineering report is based on conditions that existed atthe time the study was performed. Do not rely on a geotechnical engineer-ing report whose adequacy may have been affected by: the passage oftime; by man-made events, such as construction on or adjacent to the site;or by natural events, such as floods, earthquakes, or groundwater fluctua-tions. Always contact the geotechnical engineer before applying the reportto determine if it is still reliable. A minor amount of additional testing oranalysis could prevent major problems.

Most Geotechnical Findings Are ProfessionalOpinionsSite exploration identifies subsurface conditions only at those points wheresubsurface tests are conducted or samples are taken. Geotechnical engi-neers review field and laboratory data and then apply their professionaljudgment to render an opinion about subsurface conditions throughout thesite. Actual subsurface conditions may differ—sometimes significantly—from those indicated in your report. Retaining the geotechnical engineerwho developed your report to provide construction observation is the most effective method of managing the risks associated with unanticipatedconditions.

A Report's Recommendations Are Not FinalDo not overrely on the construction recommendations included in yourreport. Those recommendations are not final, because geotechnical engi-neers develop them principally from judgment and opinion. Geotechnicalengineers can finalize their recommendations only by observing actual

Important Information About Your

Subsurface problems are a principal cause of construction delays, cost overruns, claims, and disputes.

Geotechnical Engineering ReportThe following information is provided to help you manage your risks.

subsurface conditions revealed during construction. The geotechnicalengineer who developed your report cannot assume responsibility or liability for the report's recommendations if that engineer does not performconstruction observation.

A Geotechnical Engineering Report Is Subject toMisinterpretationOther design team members' misinterpretation of geotechnical engineeringreports has resulted in costly problems. Lower that risk by having your geo-technical engineer confer with appropriate members of the design team aftersubmitting the report. Also retain your geotechnical engineer to review perti-nent elements of the design team's plans and specifications. Contractors canalso misinterpret a geotechnical engineering report. Reduce that risk byhaving your geotechnical engineer participate in prebid and preconstructionconferences, and by providing construction observation.

Do Not Redraw the Engineer's LogsGeotechnical engineers prepare final boring and testing logs based upontheir interpretation of field logs and laboratory data. To prevent errors oromissions, the logs included in a geotechnical engineering report shouldnever be redrawn for inclusion in architectural or other design drawings.Only photographic or electronic reproduction is acceptable, but recognizethat separating logs from the report can elevate risk.

Give Contractors a Complete Report andGuidanceSome owners and design professionals mistakenly believe they can makecontractors liable for unanticipated subsurface conditions by limiting whatthey provide for bid preparation. To help prevent costly problems, give con-tractors the complete geotechnical engineering report, but preface it with aclearly written letter of transmittal. In that letter, advise contractors that thereport was not prepared for purposes of bid development and that thereport's accuracy is limited; encourage them to confer with the geotechnicalengineer who prepared the report (a modest fee may be required) and/or toconduct additional study to obtain the specific types of information theyneed or prefer. A prebid conference can also be valuable. Be sure contrac-tors have sufficient time to perform additional study. Only then might yoube in a position to give contractors the best information available to you,while requiring them to at least share some of the financial responsibilitiesstemming from unanticipated conditions.

Read Responsibility Provisions CloselySome clients, design professionals, and contractors do not recognize thatgeotechnical engineering is far less exact than other engineering disci-plines. This lack of understanding has created unrealistic expectations that

have led to disappointments, claims, and disputes. To help reduce the riskof such outcomes, geotechnical engineers commonly include a variety ofexplanatory provisions in their reports. Sometimes labeled "limitations"many of these provisions indicate where geotechnical engineers’ responsi-bilities begin and end, to help others recognize their own responsibilitiesand risks. Read these provisions closely. Ask questions. Your geotechnicalengineer should respond fully and frankly.

Geoenvironmental Concerns Are Not Covered The equipment, techniques, and personnel used to perform a geoenviron-mental study differ significantly from those used to perform a geotechnicalstudy. For that reason, a geotechnical engineering report does not usuallyrelate any geoenvironmental findings, conclusions, or recommendations;e.g., about the likelihood of encountering underground storage tanks orregulated contaminants. Unanticipated environmental problems have ledto numerous project failures. If you have not yet obtained your own geoen-vironmental information, ask your geotechnical consultant for risk man-agement guidance. Do not rely on an environmental report prepared forsomeone else.

Obtain Professional Assistance To Deal with MoldDiverse strategies can be applied during building design, construction,operation, and maintenance to prevent significant amounts of mold fromgrowing on indoor surfaces. To be effective, all such strategies should bedevised for the express purpose of mold prevention, integrated into a com-prehensive plan, and executed with diligent oversight by a professionalmold prevention consultant. Because just a small amount of water ormoisture can lead to the development of severe mold infestations, a num-ber of mold prevention strategies focus on keeping building surfaces dry.While groundwater, water infiltration, and similar issues may have beenaddressed as part of the geotechnical engineering study whose findingsare conveyed in this report, the geotechnical engineer in charge of thisproject is not a mold prevention consultant; none of the services per-formed in connection with the geotechnical engineer’s studywere designed or conducted for the purpose of mold preven-tion. Proper implementation of the recommendations conveyedin this report will not of itself be sufficient to prevent moldfrom growing in or on the structure involved.

Rely, on Your ASFE-Member GeotechncialEngineer for Additional AssistanceMembership in ASFE/The Best People on Earth exposes geotechnicalengineers to a wide array of risk management techniques that can be ofgenuine benefit for everyone involved with a construction project. Conferwith you ASFE-member geotechnical engineer for more information.

8811 Colesville Road/Suite G106, Silver Spring, MD 20910Telephone: 301/565-2733 Facsimile: 301/589-2017

e-mail: [email protected] www.asfe.org

Copyright 2004 by ASFE, Inc. Duplication, reproduction, or copying of this document, in whole or in part, by any means whatsoever, is strictly prohibited, except with ASFE’s specific written permission. Excerpting, quoting, or otherwise extracting wording from this document is permitted only with the express written permission of ASFE, and only for

purposes of scholarly research or book review. Only members of ASFE may use this document as a complement to or as an element of a geotechnical engineering report. Any otherfirm, individual, or other entity that so uses this document without being an ASFE member could be commiting negligent or intentional (fraudulent) misrepresentation.

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