11037_Double Oaks_ ECS Geotech Rpt 2013_10_18 rev 2014_4_1

REPORT
OF
LIMITED SUBSURFACE EXPLORATION
DOUBLE OAKS ROAD – WOODWARD AVENUE EXTENSION
CHARLOTTE, NORTH CAROLINA
ECS PROJECT NO. 08-9358
REVISED ON APRIL 1, 2014

REPORT OF LIMITED SUBSURFACE EXPLORATION

Double Oaks Road - Woodward Avenue Extension
Charlotte, North Carolina

Prepared For:
LandDesign 223 North Graham Street Charlotte, North Carolina 28202

Prepared By:

ECS CAROLINAS, LLP
1812 Center Park Drive, Suite D
Charlotte, North Carolina 28217

ECS Project No:

08-9358

Report Date:

Revised on April 1, 2014
Report of Limited Subsurface Exploration LandDesign
Double Oaks Road – Woodward Avenue Extension ECS Project No. 08-9358
Page 1 Revised on April 1, 2014

1. INTRODUCTION
1.1. Project Information
The project site is located at the intersection of Double Oaks Road and Woodward Avenue in
Charlotte, North Carolina as shown in the Site Vicinity Map (Figure 1) included in the Appendix.
Based on our discussions and the provided project information, a portion of road may be within
the limits of a previous landfill. Previous soil data was collected by URS and interpolated limits
of found debris were presented on a site plan by LandDesign. The interpolated limits indicated
that landfill debris may be present beneath the Woodward Avenue Extension. At this time, the
curb and gutter along the Woodward Avenue Extension as well as stone base have been
placed. Based on our discussion, approximately 4 to 5 feet of fill was placed within the roadway.

1.2. Scope of Services
Our scope of services included a limited subsurface exploration with widely spaced soil test
borings (B-1 through B-3) to depths ranging from 6.5 to 15 feet below existing grades. The
borings were performed at the approximate locations shown on the Test Location Diagram
(Figure 2) in the Appendix. The soil test borings were performed with a track-mounted SIMCO
2400 ATV drill rig using continuous-flight, hollow-stem augers.

2. FIELD SERVICES
2.1. Test Locations
The soil boring locations were selected and located in the field by ECS using existing landmarks
as reference. In addition, a representative with the Charlotte Housing Partnership, Mr. Johnny
Shout, was present to aid in the selection of the boring locations. The borings were performed
on the outside of the curb area in an effort to avoid disturbing the aggregate stone base in the
roadway. The approximate test locations are shown on the Boring Location Diagram (Figure 2)
presented in the Appendix of this report and should be considered accurate only to the degree
implied by the method used to obtain them.

2.2. Soil Test Borings
Three (3) widely spaced soil test borings were drilled to evaluate the stratification and
engineering properties of the subsurface soils at the project site. Standard Penetration Tests
(SPT’s) were performed at designated intervals in general accordance with ASTM D 1586. The
Standard Penetration Test is used to provide an index for estimating soil strength and density.
In conjunction with the penetration testing, split-barrel soil samples were recovered for soil
classification at each test interval. Boring Logs are included in the Appendix.

The drill crew also maintained a field log of the soils encountered at each of the boring locations.
After recovery, each sample was removed from the auger and visually classified.
Representative portions of each sample were then sealed and brought to our laboratory in
Charlotte, North Carolina for further visual examination. Groundwater measurements were
attempted at the termination of drilling and prior to demobilization from the project site.
Report of Limited Subsurface Exploration LandDesign
Double Oaks Road – Woodward Avenue Extension ECS Project No. 08-9358
Page 2 Revised on April 1, 2014

3. LABORATORY SERVICES
Soil samples were collected from the borings and examined in our laboratory to check field
classifications and to determine pertinent engineering properties. Data obtained from the
borings and our visual/manual examinations are included on the respective boring logs in the
Appendix.

3.1. Soil Classification
A geotechnical engineer classified each soil sample on the basis of color, texture, and plasticity
characteristics in general accordance with the Unified Soil Classification System (USCS). The
soil engineer grouped the various soil types into the major zones noted on the boring logs. The
stratification lines designating the interfaces between earth materials on the boring logs and
profiles are approximate; in situ, the transition between strata may be gradual in both the vertical
and horizontal directions. The results of the visual classifications are presented on the Boring
Logs included in the Appendix.

4. SITE AND SUBSURFACE FINDINGS
4.1. Area Geology
The site is located in the Piedmont Physiographic Province of North Carolina. The native soils in
the Piedmont Province consist mainly of residuum with underlying saprolites weathered from the
parent bedrock, which can be found in both weathered and unweathered states. Although the
surficial materials normally retain the structure of the original parent bedrock, they typically have
a much lower density and exhibit strengths and other engineering properties typical of soil. In a
mature weathering profile of the Piedmont Province, the soils are generally found to be finer
grained at the surface where more extensive weathering has occurred. The particle size of the
soils generally becomes more granular with increasing depth and gradually changes first to
weathered and finally to unweathered parent bedrock. The mineral composition of the parent
rock and the environment in which weathering occurs largely control the resulting soil's
engineering characteristics. The residual soils are the product of the weathering of the parent
bedrock.

In addition, it is apparent that the natural geology within the site has been modified in the past by
grading that included the placement of fill materials. The quality of man-made fills can vary
significantly, and it is often difficult to assess the engineering properties of existing fills.
Furthermore, there is no specific correlation between N-values from standard penetration tests
performed in soil test borings and the degree of compaction of existing fill soils; however, a
qualitative assessment of existing fills can sometimes be made based on the N-values obtained
and observations of the materials sampled in the test borings.

Report of Limited Subsurface Exploration LandDesign
Double Oaks Road – Woodward Avenue Extension ECS Project No. 08-9358
Page 3 Revised on April 1, 2014

4.2. Subsurface Conditions
The subsurface conditions at the site, as indicated by the borings, generally consisted of fill,
residual soil, partially weathered rock, and refusal materials to the depths explored. The
generalized subsurface conditions are described below. For soil stratification at a particular test
location, the respective Boring Log found in the Appendix should be reviewed.

Fill soils were encountered at the ground surface at each of the boring location. The fill
extended to depths ranging from approximately 3 to 5½ feet below the existing ground surface.
The fill soils encountered generally consisted of Silty SAND (SM) and Sandy SILT (ML)
exhibiting SPT N-values ranging from 7 to 18 blows per foot (bpf).

Residual soil was encountered below the fill at each of the boring locations. Residual soils are
formed by the in-place chemical and mechanical weathering of the parent bedrock. The residual
soils encountered in the borings generally consisted of Silty SAND (SM) and Sandy SILT (ML)
exhibiting SPT N-values ranging from 11 to 40 bpf. Borings B-1 and B-3 were terminated in
residual soil.

Partially weathered rock (PWR) was encountered below the residual soils at boring B-2 and at a
depth of approximately 5½ feet below the existing ground surface. PWR is defined as residual
material exhibiting SPT N-values greater than 100 bpf. The PWR encountered in the borings
generally consisted of Silty SAND (SM) exhibiting SPT N-values of 50 blows per 0 inches of
penetration.

Auger refusal was encountered at boring B-2 at a depth of approximately 6½ feet below the
existing ground surface. Auger refusal indicates the presence of material that permitted no
further advancement of the hollow stem auger or split spoon sampler. No sample was
recovered in the split-spoon sampler. Rock core samples were beyond the scope of this
exploration.

4.3. Groundwater Observations
Groundwater measurements were attempted at the termination of drilling and prior to
demobilizing from the project site. No groundwater was encountered at the boring locations at
the time of our exploration within the depths explored. Fluctuations in the groundwater elevation
should be expected depending on precipitation, run-off, utility leaks, and other factors not
evident at the time of our evaluation. Normally, highest groundwater levels occur in late winter
and spring and the lowest levels occur in late summer and fall.

5. CONCLUSIONS
The widely spaced borings performed at this site represent the subsurface conditions at the
location of the borings. Due to inconsistencies associated with fill and the prevailing geology,
there can be changes in the subsurface conditions over relatively short distances that have not
been disclosed by the results of the test location performed. Consequently, there may be
undisclosed subsurface conditions that require special treatment or additional preparation once
these conditions are revealed during construction.

Fill soils were encountered at the ground surface at each of the boring locations. The fill
extended to depths ranging from approximately 3 to 5½ feet below the existing ground surface.
The existing fill observed within the tested locations appeared free of concentrated organics and
debris. Based on previous available soil borings (ECS Project No. 08-4442-B, dated July 13,
2007), the landfill debris was dark in color with concentrated amounts of debris within the boring
Report of Limited Subsurface Exploration LandDesign
Double Oaks Road – Woodward Avenue Extension ECS Project No. 08-9358
Page 4 Revised on April 1, 2014

locations. Evidence of this landfill debris was not present within the borings performed during
this limited subsurface exploration.

ECS was not provided with documentation of the previous earthwork activities within the
Woodward Avenue Extension, thus the fill should be considered undocumented. Undocumented
fill poses risks associated with undetected deleterious inclusions within the fill and/or deleterious
materials at the virgin ground fill interface that are covered by the fill. If the owner possesses
compaction data from previous earthwork activities, ECS should be given the opportunity to
review this data and make revisions to this report if needed. However, based on our discussion
with Mr. Johnny Shout, with Charlotte Housing Partnership, we understand the landfill debris
was not encountered within the limits of the roadway during construction.

The Woodward Avenue Extension is currently at grade with aggregate base course (ABC) stone
and curbing in place prior to asphalt pavement. Although limited information has been provided
to ECS regarding preparation of the subgrade soils, the N-values within the soil test borings
indicate the existing fill material was placed with some compactive effort. Therefore, pending a
successful proofroll of the ABC stone prior to asphalt pavement, the soils at the tested locations
appear generally suitable for support of the roadway.

6. GENERAL COMMENTS
The widely spaced borings performed at this site represent the subsurface conditions at the
location of the borings only. Due to the prevailing geology and fill material, changes in the
subsurface conditions can occur over relatively short distances that have not been disclosed by
the results of the borings performed. ECS has attempted to be as specific as feasible with the
limited information available.

Our limited subsurface exploration has been based on our understanding of the site and project
information and the data obtained. The general subsurface conditions utilized in our limited
subsurface exploration have been based on interpolation of subsurface data between and away
from the test holes. The discovery of any site or subsurface conditions during construction
which deviate from the data outlined in this exploration should be reported to us for our
evaluation. The assessment of site environmental conditions for the presence of pollutants in
the soil, rock, and groundwater of the site was beyond the scope of this exploration.

The recommendations outlined herein should not be construed to address moisture or water
intrusion effects after construction is completed. Proper design of landscaping, surface and
subsurface water control measures are required to properly address these issues. In addition,
proper operation and maintenance of building systems is required to minimize the effects of
moisture or water intrusion. The design, construction, operation, and maintenance of
waterproofing and dampproofing systems are beyond the scope of services for this project.
REVISIONS
DRAFTSMAN
PROJ. MGR.
DATE
FIGURE
PROJECT NO.
SCALESource:
TLH
1
LEGEND:
Google Maps
EHF
08-9358
10-08-13
N.T.S.FIGURE 1
SITE VICINITY MAP
Double Oaks Woodward Ave.
Debris DTR
Charlotte, NC
B-1
B-2
B-3
REVISIONS
DRAFTSMAN
PROJ. MGR.
DATE
FIGURE
PROJECT NO.
SCALEBackground Image Provided by:
TLH
2
LEGEND:
N.T.S.EHF
08-9358
10-08-13
FIGURE 2
BORING LOCATION DIAGRAM
Double Oaks Woodward Ave.
Debris DTR
Charlotte, NC
= Approximate Location of Boring

Client Provided
0
5
10
15
20
25
30
S-1
S-2
S-3
S-4
S-5
SS
SS
SS
SS
SS
18
18
18
18
18
10
16
14
18
18
FILL - Loose, Brown, Silty Fine to Medium
SAND, Moist (FILL - SM)
RESIDUAL - Stiff, Brown, Sandy SILT, Moist
(ML)
Hard, Olive, Sandy SILT, Moist (ML)
END OF BORING @ 15.0'
4
4
5
3
3
4
5
5
8
8
14
26
7
14
21
9
7
13
40
35
CLIENT
Land Design
JOB #
9358
BORING #
B-1
SHEET
PROJECT NAME
Double Oaks Woodward Ave. Debris â DTR
ARCHITECT-ENGINEER
SITE LOCATION
Woodward avenue and double oaks road., Charlotte, Mecklenburg County
NORTHING EASTING STATION
THE STRATIFICATION LINES REPRESENT THE APPROXIMATE BOUNDARY LINES BETWEEN SOIL TYPES. IN-SITU THE TRANSITION MAY BE GRADUAL.
WL GNE WS WD BORING STARTED 10/07/13
WL(BCR)WL(ACR) GNE BORING COMPLETED 10/07/13 CAVE IN DEPTH @ 11.1'
WL RIG SIMCO 2400 FOREMAN Cody DRILLING METHOD 2.25 HSA
DE
P
T
H

(
F
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)
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SA
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SA
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D
I
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T
.

(
I
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RE
C
O
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Y

(
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)
SURFACE ELEVATION
DESCRIPTION OF MATERIAL
WA
T
E
R

L
E
V
E
L
S
EL
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A
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(
F
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BL
O
W
S
/
6
"
10 20 30 40 50+
20% 40% 60% 80% 100%
1 2 3 4 5+
ENGLISH UNITS
BOTTOM OF CASING LOSS OF CIRCULATION
CALIBRATED PENETROMETER TONS/FT2
PLASTIC
LIMIT %
WATER
CONTENT %
LIQUID
LIMIT %
ROCK QUALITY DESIGNATION & RECOVERY
RQD% REC.%
STANDARD PENETRATION
BLOWS/FT
1 OF 1
0
5
10
15
20
25
30
S-1
S-2
S-3
SS
SS
SS
18
18
6
16
14
6
FILL - Medium Stiff, Reddish Brown, Sandy
SILT, Moist (FILL - ML)
RESIDUAL - Medium Dense, Olive, Silty Fine to
Medium SAND, Moist (SM)
PARTIALLY WEATHERED ROCK - Olive, Silty
Fine to Medium SAND, (PWR)
AUGER REFUSAL @ 6.5'
3
5
3
5
5
6
4
50/0
8
11
100+
CLIENT
Land Design
JOB #
9358
BORING #
B-2
SHEET
PROJECT NAME
Double Oaks Woodward Ave. Debris â DTR
ARCHITECT-ENGINEER
SITE LOCATION
Woodward avenue and double oaks road., Charlotte, Mecklenburg County
NORTHING EASTING STATION
THE STRATIFICATION LINES REPRESENT THE APPROXIMATE BOUNDARY LINES BETWEEN SOIL TYPES. IN-SITU THE TRANSITION MAY BE GRADUAL.
WL GNE WS WD BORING STARTED 10/07/13
WL(BCR)WL(ACR) GNE BORING COMPLETED 10/07/13 CAVE IN DEPTH @ 5.3'
WL RIG SIMCO 2400 FOREMAN Cody DRILLING METHOD 2.25 HSA
DE
P
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H

(
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)
SA
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N
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D
I
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.

(
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RE
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Y

(
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)
SURFACE ELEVATION
DESCRIPTION OF MATERIAL
WA
T
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R

L
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V
E
L
S
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V
A
T
I
O
N

(
F
T
)
BL
O
W
S
/
6
"
10 20 30 40 50+
20% 40% 60% 80% 100%
1 2 3 4 5+
ENGLISH UNITS
BOTTOM OF CASING LOSS OF CIRCULATION
CALIBRATED PENETROMETER TONS/FT2
PLASTIC
LIMIT %
WATER
CONTENT %
LIQUID
LIMIT %
ROCK QUALITY DESIGNATION & RECOVERY
RQD% REC.%
STANDARD PENETRATION
BLOWS/FT
1 OF 1
0
5
10
15
20
25
30
S-1
S-2
S-3
S-4
S-5
SS
SS
SS
SS
SS
18
18
18
18
18
18
18
14
18
12
FILL - Stiff to Very Stiff, Brown, Sandy SILT,
Moist (FILL - ML)
RESIDUAL - Stiff, Olive, Sandy SILT, Moist
(ML)
Hard to Very Stiff, Olive, Sandy SILT, Moist
(ML)
END OF BORING @ 15.0'
5
6
4
7
8
10
4
6
9
10
17
17
7
11
16
10
18
15
34
27
CLIENT
Land Design
JOB #
9358
BORING #
B-3
SHEET
PROJECT NAME
Double Oaks Woodward Ave. Debris â DTR
ARCHITECT-ENGINEER
SITE LOCATION
Woodward avenue and double oaks road., Charlotte, Mecklenburg County
NORTHING EASTING STATION
THE STRATIFICATION LINES REPRESENT THE APPROXIMATE BOUNDARY LINES BETWEEN SOIL TYPES. IN-SITU THE TRANSITION MAY BE GRADUAL.
WL GNE WS WD BORING STARTED 10/07/13
WL(BCR)WL(ACR) GNE BORING COMPLETED 10/07/13 CAVE IN DEPTH @ 11.4'
WL RIG SIMCO 2400 FOREMAN Cody DRILLING METHOD 2.25 HSA
DE
P
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H

(
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)
SA
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N
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(
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SURFACE ELEVATION
DESCRIPTION OF MATERIAL
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(
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S
/
6
"
10 20 30 40 50+
20% 40% 60% 80% 100%
1 2 3 4 5+
ENGLISH UNITS
BOTTOM OF CASING LOSS OF CIRCULATION
CALIBRATED PENETROMETER TONS/FT2
PLASTIC
LIMIT %
WATER
CONTENT %
LIQUID
LIMIT %
ROCK QUALITY DESIGNATION & RECOVERY
RQD% REC.%
STANDARD PENETRATION
BLOWS/FT
1 OF 1

Major Divisions Group
Symbols Typical Names Laboratory Classification Criteria
GW Well graded gravels, gravel-
sand mixtures, little or no fines
Cu=D60/D10 greater than 4
Cc= (D30)2/(D10 x D60) between 1 and 3
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Silty Gravels, gravel-sand-silt
mixtures
Atterberg limits
below “A” line or P.I.
less than 4
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above “A” line with
P.I. greater than 7
Above “A” line with P.I.
between 4 and 7 are
borderline cases requiring
use of dual symbols
SW Well-graded sands, gravelly
sands, little or no fines
Cu=D60/D10 greater than 6
Cc= (D30)2/(D10 x D60) between 1 and 3
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SP Poorly graded sands, gravelly
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above “A” line with
P.I. greater than 7
Limits plotting in hatched
zone with P.I. between 4
and 7 are borderline cases
requiring use of dual
symbols
ML
Inorganic silts and very fine sands,
rock flour, silty or clayey fine
sands, or clayey silts with slight
plasticity
CL
Inorganic clays of low to medium
plasticity, gravelly clays, sandy
clays, silty clays, lean clays
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OL Organic silts and organic silty
clays of low plasticity
MH Inorganic silts, micaceous or
diatomaceous fine sandy or silty
soils, elastic silts
CH Inorganic clays of high plasticity,
fat clays
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Pt Peat and other highly organic soils
Reference: Winterkorn & Fang, 1975 (ASTM D-2487)
aDivision of GM and SM groups into subdivision of d and u are for road and airfields only. Subdivision is based on Atterberg limits; suffix d used
when L.L. is 28 or less and the P.I. is 6 or less; the suffix u is used when L.L. is greater that 28. bBorderline classifications, used for soils possessing characteristics of two groups, are designated by combinations of group symbols. For example:
GW-GC, well-graded gravel-sand mixture with clay binder.

UNIFIED SOIL
CLASSIFICATION SYSTEM
1812 CENTER PARK DRIVE
SUITE D
CHARLOTTE, NC 28217
704/525-5152
FAX/704-357-0023

REFERENCE NOTES FOR BORING LOGS

I. Drilling Sampling Symbols

SS Split Spoon Sampler ST Shelby Tube Sampler
RC Rock Core, NX, BX, AX PM Pressuremeter
DC Dutch Cone Penetrometer RD Rock Bit Drilling
BS Bulk Sample of Cuttings PA Power Auger (no sample)
HSA Hollow Stem Auger WS Wash sample
REC Rock Sample Recovery % RQD Rock Quality Designation %

II. Correlation of Penetration Resistances to Soil Properties
Standard Penetration (blows/ft) refers to the blows per foot of a 140 lb. hammer falling 30
inches on a 2-inch OD split-spoon sampler, as specified in ASTM D 1586. The blow count is
commonly referred to as the N-value.
A. Non-Cohesive Soils (Silt, Sand, Gravel and Combinations)
Density Relative Properties
Under 4 blows/ft Very Loose Adjective Form 12% to 49%
5 to 10 blows/ft Loose With 5% to 12%
11 to 30 blows/ft Medium Dense
31 to 50 blows/ft Dense
Over 51 blows/ft Very Dense

Particle Size Identification
Boulders 8 inches or larger
Cobbles 3 to 8 inches
Gravel Coarse 1 to 3 inches
Medium ½ to 1 inch
Fine ¼ to ½ inch
Sand Coarse 2.00 mm to ¼ inch (dia. of lead pencil)
Medium 0.42 to 2.00 mm (dia. of broom straw)
Fine 0.074 to 0.42 mm (dia. of human hair)
Silt and Clay 0.0 to 0.074 mm (particles cannot be seen)

B. Cohesive Soils (Clay, Silt, and Combinations)
Blows/ft Consistency
Unconfined
Comp. Strength
Qp (tsf)
Degree of
Plasticity
Plasticity
Index
Under 2 Very Soft Under 0.25 None to slight 0 – 4
3 to 4 Soft 0.25-0.49 Slight 5 – 7
5 to 8 Medium Stiff 0.50-0.99 Medium 8 – 22
9 to 15 Stiff 1.00-1.99 High to Very High Over 22
16 to 30 Very Stiff 2.00-3.00
31 to 50 Hard 4.00–8.00
Over 51 Very Hard Over 8.00

III. Water Level Measurement Symbols

WL Water Level BCR Before Casing Removal DCI Dry Cave-In
WS While Sampling ACR After Casing Removal WCI Wet Cave-In
WD While Drilling Est. Groundwater Level Est. Seasonal High GWT

The water levels are those levels actually measured in the borehole at the times indicated by the
symbol. The measurements are relatively reliable when augering, without adding fluids, in a granular
soil. In clay and plastic silts, the accurate determination of water levels may require several days for
the water level to stabilize. In such cases, additional methods of measurement are generally applied.
Important Information About Your
Geotechnical Engineering Report
Subsurface problems are a principal cause of construction delays, cost overruns, claims, and disputes
The following information is provided to help you manage your risks.
Geotechnical Services Are Performed for
Specifi c Purposes, Persons, and Projects
Geotechnical engineers structure their services to meet the specifi c needs of
their clients. A geotechnical engineering study conducted for a civil engineer
may not fulfi ll the needs of a construction contractor or even another civil
engineer. Because each geotechnical engineering study is unique, each geo-
technical engineering report is unique, prepared solely for the client. No one
except you should rely on your geotechnical engineering report without fi rst
conferring with the geotechnical engineer who prepared it. And no one - not
even you - should apply the report for any purpose or project except the one
originally contemplated.
Read the Full Report
Serious problems have occurred because those relying on a geotechnical
engineering 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-Specifi c Factors
Geotechnical engineers consider a number of unique, project-specifi c factors
when establishing the scope of a study. Typical factors include: the client’s
goals, objectives, and risk management preferences; the general nature of the
structure involved, its size, and confi guration; the location of the structure
on the site; and other planned or existing site improvements, such as access
roads, parking lots, and underground utilities. Unless the geotechnical engi-
neer who conducted the study specifi cally indicates otherwise, do not rely on
a geotechnical engineering report that was:
• not prepared for you,
• not prepared for your project,
• not prepared for the specifi c site explored, or
• completed before important project changes were made.
Typical changes that can erode the reliability of an existing geotechnical
engineering report include those that affect:
• the function of the proposed structure, as when it’s changed from a
parking garage to an offi ce building, or from alight industrial plant
to a refrigerated warehouse,
• elevation, confi guration, 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 project
changes - even minor ones - and request an assessment of their impact.
Geotechnical engineers cannot accept responsibility or liability for problems
that occur because their reports do not consider developments of which they
were not informed.
Subsurface Conditions Can Change
A geotechnical engineering report is based on conditions that existed at the
time the study was performed. Do not rely on a geotechnical engineering
report whose adequacy may have been affected by: the passage of time; by
man-made events, such as construction on or adjacent to the site; or by natu-
ral events, such as fl oods, earthquakes, or groundwater fl uctuations. Always
contact the geotechnical engineer before applying the report to determine if it
is still reliable. A minor amount of additional testing or analysis could prevent
major problems.
Most Geotechnical Findings Are Professional
Opinions
Site exploration identifi es subsurface conditions only at those points where
subsurface tests are conducted or samples are taken. Geotechnical engineers
review fi eld and laboratory data and then apply their professional judgment
to render an opinion about subsurface conditions throughout the site. Actual
subsurface conditions may differ-sometimes signifi cantly from those indi-
cated in your report. Retaining the geotechnical engineer who developed your
report to provide construction observation is the most effective method of
managing the risks associated with unanticipated conditions.
A Report’s Recommendations Are Not Final
Do not overrely on the construction recommendations included in your re-
port. Those recommendations are not fi nal, because geotechnical engineers
develop them principally from judgment and opinion. Geotechnical engineers
can fi nalize their recommendations only by observing actual
subsurface conditions revealed during construction. The geotechnical engi-
neer who developed your report cannot assume responsibility or liability for
the report’s recommendations if that engineer does not perform construction
observation.
A Geotechnical Engineering Report Is Subject to
Misinterpretation
Other design team members’ misinterpretation of geotechnical engineer-
ing reports has resulted in costly problems. Lower that risk by having your
geotechnical engineer confer with appropriate members of the design team
after submitting the report. Also retain your geotechnical engineer to review
pertinent elements of the design team’s plans and specifi cations. Contractors
can also misinterpret a geotechnical engineering report. Reduce that risk by
having your geotechnical engineer participate in prebid and preconstruction
conferences, and by providing construction observation.
Do Not Redraw the Engineer’s Logs
Geotechnical engineers prepare fi nal boring and testing logs based upon
their interpretation of fi eld logs and laboratory data. To prevent errors or
omissions, the logs included in a geotechnical engineering report should
never be redrawn for inclusion in architectural or other design drawings.
Only photographic or electronic reproduction is acceptable, but recognize
that separating logs from the report can elevate risk.
Give Contractors a Complete Report and
Guidance
Some owners and design professionals mistakenly believe they can make
contractors liable for unanticipated subsurface conditions by limiting what
they provide for bid preparation. To help prevent costly problems, give con-
tractors the complete geotechnical engineering report, but preface it with a
clearly written letter of transmittal. In that letter, advise contractors that the
report was not prepared for purposes of bid development and that the report’s
accuracy is limited; encourage them to confer with the geotechnical engineer
who prepared the report (a modest fee may be required) and/or to conduct ad-
ditional study to obtain the specifi c types of information they need or prefer.
A prebid conference can also be valuable. Be sure contractors have suffi cient
time to perform additional study. Only then might you be in a position to give
contractors the best information available to you, while requiring them to at
least share some of the fi nancial responsibilities stemming from unantici-
pated conditions.
Read Responsibility Provisions Closely
Some clients, design professionals, and contractors do not recognize that
geotechnical engineering is far less exact than other engineering disciplines.
This lack of understanding has created unrealistic expectations that have led
to disappointments, claims, and disputes. To help reduce the risk of such
outcomes, geotechnical engineers commonly include a variety of explanatory
provisions in their reports. Sometimes labeled “limitations” many of these
provisions indicate where geotechnical engineers’ responsibilities begin
and end, to help others recognize their own responsibilities and risks. Read
these provisions closely. Ask questions. Your geotechnical engineer should
respond fully and frankly.
Geoenvironmental Concerns Are Not Covered
The equipment, techniques, and personnel used to perform a geoenviron-
mental study differ signifi cantly from those used to perform a geotechnical
study. For that reason, a geotechnical engineering report does not usually re-
late any geoenvironmental fi ndings, conclusions, or recommendations; e.g.,
about the likelihood of encountering underground storage tanks or regulated
contaminants. Unanticipated environmental problems have led to numerous
project failures. If you have not yet obtained your own geoenvironmental in-
formation, ask your geotechnical consultant for risk management guidance.
Do not rely on an environmental report prepared for someone else.
Obtain Professional Assistance To Deal with Mold
Diverse strategies can be applied during building design, construction, op-
eration, and maintenance to prevent signifi cant amounts of mold from grow-
ing on indoor surfaces. To be effective, all such strategies should be devised
for the express purpose of mold prevention, integrated into a comprehensive
plan, and executed with diligent oversight by a professional mold prevention
consultant. Because just a small amount of water or moisture can lead to
the development of severe mold infestations, a number of mold prevention
strategies focus on keeping building surfaces dry. While groundwater, wa-
ter infi ltration, and similar issues may have been addressed as part of the
geotechnical engineering study whose fi ndings are conveyed in-this report,
the geotechnical engineer in charge of this project is not a mold prevention
consultant; none of the services performed in connection with
the geotechnical engineer’s study were designed or conducted
for the purpose of mold prevention. Proper implementation of
the recommendations conveyed in this report will not of itself
be suffi cient to prevent mold from growing in or on the struc-
ture involved.
Rely on Your ASFE-Member Geotechnical
Engineer For Additional Assistance
Membership in ASFE/The Best People on Earth exposes geotechnical engi-
neers to a wide array of risk management techniques that can be of genuine
benefi t for everyone involved with a construction project. Confer with your
ASFE-member geotechnical engineer for more information.
8811 Colesville Road/Suite G106, Silver Spring, MD 20910
Telephone:’ 301/565-2733 Facsimile: 301/589-2017
e-mail: [e-mail] 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 specifi c
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 other fi rm,
individual, or other entity that so uses this document without being anASFE member could be committing negligent or intentional (fraudulent) misrepresentation.
IIGER06045.0M
The Best People on Earth