20170370 GeoTec Evaluation Ltr 08292017INSIGHT GEOLOGIC, INC.
August 29, 2017
J. W. Morrissette & Associates
1700 Cooper Point Road SW
Suite B -2
Olympia, Washington 98502
Attention: Scott Severs
Report
Geotechnical and Groundwater Evaluation
Proposed Yelm High School Bypass Road
Yelm, Washington
Project No. 847 - 004 -01
INTRODUCTION
Insight Geologic, Inc. is pleased to provide our report for the evaluation of subsurface conditions at
the location of the proposed Yelm High School Bypass Road in Yelm, Washington. The location of
the site is shown relative to surrounding physical features in the Vicinity Map, Figure 1. The road will
connect Tahoma Boulevard SE on the south and Yelm High School on the north to reduce traffic on
Yelm Boulevard. The proposed roadway alignment crosses a low swale that could be impacted by
high groundwater during winter months and may impact stormwater infiltration. Currently, the property
for the roadway is not developed and is vegetated with grass and brush.
Our services were performed in general accordance with our proposal dated May 1, 2017 and
authorized on July 17, 2017.
SCOPE OF SERVICES
The purpose of our services was to provide geotechnical properties of the site soils for the road as
well as evaluating winter high ground water levels. The specific tasks performed are outlined as
follows.
1. Provide for the location of subsurface utilities at the site. We proposed using the One Call utility
location system for this task.
2. Explored the subsurface soil conditions at the site by advancing five (5) exploratory test pits along
the proposed alignment. The test pits were excavated using a backhoe and extended to 6 feet
below ground surface (bgs).
3. Log the soils encountered in the test pits in general accordance with the Unified Soil Classification
System (ASTM D2487). Detailed logs of the borings were completed in the field.
4. Collect representative soil samples from the test pits for laboratory analyses.
1015 EAST 4TH AVENUE, OLYMPIA, WASHINGTON 98506
PHONE: 360.754.2128 FAx:360.754.9299
Yelm High School Bypass Road
Geotechnical and Groundwater Evaluation Report
August 29, 2017
5. Install one (1) monitoring well with piezometer for groundwater monitoring in the low area of the
project site. The well consisted of 1 -inch diameter casing and screen, and extended to the depth
of 9 feet bgs. The piezometer was completed inside the locking steel monument.
6. Prepare a final written report for the project presenting our conclusions and recommendations for
site grading, retaining walls, pavement design, estimated design infiltration rates for stormwater,
along with our supporting field and laboratory information.
FINDINGS
Surface Conditions
The project site is situated at an elevation between 342 and 326 feet above mean sea level (MSL) and
is currently undeveloped. The site is bounded by Yelm High School to the north, Tahoma Boulevard
SE to the south, and undeveloped parcels to the east and west. The northern portion of the site is
relatively level with a moderate slope between the northern third and central third of the site. The
southern portion of the site gently slopes north to the central portion of the site. The property is covered
in grasses, scotch broom, and blackberry bushes, with scattered groves of pine trees, and the northern
third of the site is wooded. An existing well house is located on the western edge of the subject
property.
Geology
Based on our review of available published geologic maps, Vashon age glacial outwash deposits
underlie the project site and surrounding area. This material is described as continental glacial
outwash gravels. This material was deposited by outwash rivers during the waning stages of the most
recent glacial period in the Puget Sound and is not glacially consolidated.
Subsurface Explorations
We explored subsurface conditions at the site on August 3 and 4, 2017 by advancing one boring and
excavating five test pits in the locations as shown on the Site Plan, Figure 2 and Table 1, below. The
exploratory borings were completed by Standard Environmental Probe using a Geoprobe 5410 direct
push drill rig. The test pits were excavated using a track - mounted excavator. A geologist from Insight
Geologic monitored the explorations and maintained a log of the conditions encountered. The boring
was completed at the depth of 12 feet bgs and the test pits were completed at the depth of 6 feet bgs.
The soils were visually classified in general accordance with the system described in ASTM D2487-
06. A key to our exploration logs and the explorations are contained in Attachment A.
Table 1. Exploration Location Stationing
Exploration Name
Approximate Station Location
TP -1
Approximately 100 feet west of station 10 +80
TP -2
7 +00
TP -3
8 +60
TP -4
13 +00
TP -5
15 +40
MW -1
Approximately 120 feet west of station 10 +90
FILE • 847-004-01 I I T GE0L0GIC, VNC.
Yelm High School Bypass Road
Geotechnical and Groundwater Evaluation Report
August 29, 2017
The monitoring well installed in the boring consists of 1 -inch diameter casing and screen to the depth
of 9 feet bgs. The well was installed with a tamper resistant steel cover, flush with the surrounding
grade. The monitoring well construction details are included in Attachment A.
Soil Conditions
Surface conditions encountered within the explorations were consistent across the site, with one
exception. Soils within test pits TP -1 to TP -4 and MW -1 generally consisted of dark brown to brown
fine to coarse gravel with sand and cobbles (GP) in a dry to moist and loose to medium dense
condition. Soils within test pit TP -5 consisted of brown fine to medium sand with occasional gravel
(SP) in a dry to moist and loose to medium dense condition.
The soils encountered are consistent with Spanaway gravelly sandy loam and Nisqually loamy fine
sand, which is mapped for the majority of the site. These soils are generally formed from glacial
outwash and generally have restrictive layers occurring greater than 7 feet below grade. Percolation
is high, with rates between 1.98 and 5.95 inches per hour, according to the U.S. Department of
Agriculture Soil Survey. Surficial site soils are identified in Attachment B.
Groundwater Conditions
Groundwater was not encountered in any of the explorations completed at the site. No evidence of
seasonal high groundwater was encountered within the explorations.
Laboratory Testing
We selected six soil samples for gradation analyses in general accordance with ASTM D422 to define
soil class and obtain parameters for stormwater infiltration calculations. Our laboratory test results are
provided in Attachment C.
"TORMWATER INFILTRATION
We completed a stormwater infiltration rate evaluation in general accordance with the Washington
State Department of Ecology Stormwater Manual for Western Washington (SMWW) as adopted by
the City of Yelm. For the purposes of this evaluation, we selected Method 2, "ASTM Gradation Testing
at Full Scale Infiltration Facilities" to estimate the long -term design infiltration rates at the site. Method
2 is based on the Dio results of the ASTM grain -size distribution analyses to estimate long -term design
infiltration rates. The Method 2 values are listed in Table 3.8 of Volume III of the SMWW. To better
identify infiltration rates for soils having Dio values which lie between the values listed in the table, we
have plotted those values graphically and calculated a best -fit line to the data. The equation for the
best fit line is y = 23.3x — 0.5, where "y" is the infiltration rate in inches per hour and "x" is the Dio value
as determined by the ASTM gradation testing. By substituting our Dio sample values for "x" in the
equation, we are able to calculate design infiltration rates (Fdesign) for each analyzed sample.
Based on our analyses, we estimate that long -term design infiltration rates (Fdesign) for the infiltration
pond area is 6.5 inches per hour, based on the lowest rate found at the infiltration pond location. The
results of our stormwater infiltration evaluation are presented in Table 2.
FILE • 847-004-01 I I T C8E ®L ®GIC, VNC.
Yelm High School Bypass Road
Geotechnical and Groundwater Evaluation Report
August 29, 2017
Table 2. Design Infiltration Rates — Simple Method
Exploration Name
Unit
Depth Range
(feet)
Dio Value
Design Infiltration Rate
(inches per hour)
TP -1
GP
2.0-6.0
0.85
19.3
TP -2
GP
1.0-6.0
0.65
14.6
TP-3
GP
0.0-1.0
1.1
20
TP-3
GP
1.0-6.0
1.0
20
TP-5
SP
2.0-6.0
0.2
4.2
MW -1
GP
10.0-12.0
0.3
6.5
CONCLUSIONS AND RECOMMENDATIONS
General
Based on the results of our review, subsurface explorations and engineering analyses, it is our opinion
that the proposed roadway is feasible from a geotechnical standpoint.
The soils encountered in our explorations are typically in a loose condition near ground surface. To
limit the potential for structure settlement, we recommend that shallow foundations and slabs -on -grade
be established on a minimum 1 -foot thick layer of structural fill. Depending on final grading plans and
the time of year earthwork is performed; it could be practical to reuse the on -site soils as structural fill
under the foundations /slabs.
Stormwater infiltration at the site is feasible. We have provided a design infiltration rate of 6.5 inches
per hour for the proposed stormwater infiltration system.
Winter high groundwater monitoring will be conducted between December 2017 and March 2018, with
a data - logging pressure transducer maintaining a record of the site groundwater levels within the
monitoring well. Following completion of the study, we will prepare a report regarding site suitability
for stormwater infiltration including our groundwater monitoring data and final long -term infiltration rate
with any additional recommendations, as appropriate.
Earthwork
General
We anticipate that site development earthwork will include clearing and stripping of existing vegetation,
preparing subgrades, excavating for utility trenches, and placing and compacting structural fill. We
expect that the majority of site grading can be accomplished with conventional earth moving equipment
in proper working order.
Our explorations did not encounter appreciable amounts of debris or unsuitable soils associated with
past site development. Still, it is possible that concrete slabs, abandoned utility lines or other
development features could be encountered during construction. The contractor should be prepared
to deal with these conditions.
FILE • . 847-004-01 4 I I T GE0L0GIC, VNC.
Yelm High School Bypass Road
Geotechnical and Groundwater Evaluation Report
August 29, 2017
Clearing and Stripping
Clearing and stripping should consist of removing surface and subsurface deleterious materials
including sod /topsoil, trees, brush, debris and other unsuitable loose /soft or organic materials.
Stripping and clearing should extend at least 5 feet beyond all structures and areas to receive
structural fill.
We estimate that a stripping depth of about 0.5 feet will be required to remove the surficial organic
layer encountered in our explorations. Deeper stripping depths may be required if additional
unsuitable soils are exposed during stripping operations. We recommend that trees be removed by
overturning so that the majority of roots are also removed. Depressions created by tree or stump
removal should be backfilled with structural fill and properly compacted.
Subgrade Preparation
After stripping and excavating to the proposed subgrade elevation, and before placing structural fill,
the exposed subgrade should be thoroughly compacted to a firm and unyielding condition. The
exposed subgrade should then be proof - rolled using loaded, rubber -tired heavy equipment. We
recommend that Insight Geologic be retained to observe the proof - rolling prior to placement of
structural fill or foundation concrete. Areas of limited access that cannot be proof - rolled can be
evaluated using a steel probe rod. If soft or otherwise unsuitable areas are revealed during proof -
rolling or probing, that cannot be compacted to a stable and uniformly firm condition, we generally
recommend that: 1) the subgrade soils be scarified (e.g., with a ripper or farmer's disc), aerated and
recompacted; or 2) the unsuitable soils be overexcavated and replaced with structural fill.
Temporary Excavations and Groundwater Handling
Excavations deeper than 4 feet should be shored or laid back at a stable slope if workers are required
to enter. Shoring and temporary slope inclinations must conform to the provisions of Title 296
Washington Administrative Code (WAC), Part N, "Excavation, Trenching and Shoring." Regardless of
the soil type encountered in the excavation, shoring, trench boxes or sloped sidewalls were required
under the Washington Industrial Safety and Health Act (WISHA). The contract documents should
specify that the contractor is responsible for selecting excavation and dewatering methods, monitoring
the excavations for safety and providing shoring, as required, to protect personnel and structures.
In general, temporary cut slopes should be inclined no steeper than about 1.5H:1V (horizontal:
vertical). This guideline assumes that all surface loads are kept at a minimum distance of at least one -
half the depth of the cut away from the top of the slope, and that significant seepage is not present on
the slope face. Flatter cut slopes were necessary where significant seepage occurs or if large voids
are created during excavation. Some sloughing and raveling of cut slopes should be expected.
Temporary covering with heavy plastic sheeting should be used to protect slopes during periods of
wet weather.
We anticipate that if perched groundwater is encountered during construction can be handled
adequately with sumps, pumps, and /or diversion ditches. Groundwater handling needs will generally
be lower during the late summer and early fall months. We recommend that the contractor performing
FILE • 847-004-01 AIM T C8E ®L®GIC, VNC.
Yelm High School Bypass Road
Geotechnical and Groundwater Evaluation Report
August 29, 2017
the work be made responsible for controlling and collecting groundwater encountered during
construction.
Permanent Slopes
We anticipate that permanent slopes will be utilized for the proposed project in the area of the
stormwater pond and possibly in the area where the roadway is expected to cross the steeper slope
near the northern portion of the site. Where permanent slopes are necessary, we recommend the
slopes be constructed at a maximum inclination of 2HAV. Where 2H:1V permanent slopes are not
feasible, protective facings and /or retaining structures should be considered.
To achieve uniform compaction, we recommend that fill slopes be overbuilt and subsequently cut back
to expose well- compacted fill. Fill placement on slopes should be benched into the slope face and
include keyways. The configuration of the bench and keyway depends on the equipment being used.
Bench excavations should be level and extend into the slope face. We recommend that a vertical cut
of about 3 feet be maintained for benched excavations. Keyways should be about 1 -1/2 times the
width of the equipment used for grading or compaction.
Erosion Control
We anticipate that erosion control measures such as silt fences, straw bales and sand bags will
generally be adequate during development. Temporary erosion control should be provided during
construction activities and until permanent erosion control measures are functional. Surface water
runoff should be properly contained and channeled using drainage ditches, berms, swales, and
tightlines, and should not discharge onto sloped areas. Any disturbed sloped areas should be
protected with a temporary covering until new vegetation can take effect. Jute or coconut fiber matting,
excelsior matting or clear plastic sheeting is suitable for this purpose. Graded or disturbed slopes
should be tracked in -place with the equipment running perpendicular to the slope contours so that the
track marks provide a texture to help resist erosion. Ultimately, erosion control measures should be
in accordance with local regulations and should be clearly described on project plans.
Wet Weather Earthwork
Some of the near surface soils contain up to near 5 percent fines. While this soil is generally
considered to be well drained, significant rainfall may increase the moisture content of this soil more
than a few percent above the optimum moisture content, increasing the likelihood that the soil will
become unstable and it may become difficult or impossible to meet the required compaction criteria.
Disturbance of near surface soils should be expected if earthwork is completed during periods of wet
weather.
The wet weather season in this area generally begins in October and continues through May.
However, periods of wet weather may occur during any month of the year. If wet weather earthwork
is unavoidable, we recommend that:
• The ground surface is sloped so that surface water is collected and directed away from the work
area to an approved collection /dispersion point.
• Earthwork activities not take place during periods of heavy precipitation.
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Yelm High School Bypass Road
Geotechnical and Groundwater Evaluation Report
August 29, 2017
• Slopes with exposed soil be covered with plastic sheeting or otherwise protected from erosion.
• Measures are taken to prevent on -site soil and soil stockpiles from becoming wet or unstable.
Sealing the surficial soil by rolling with a smooth -drum roller prior to periods of precipitation should
reduce the extent that the soil becomes wet or unstable.
• Construction traffic is restricted to specific areas of the site, preferably areas that are surfaced with
materials not susceptible to wet weather disturbance.
• A minimum 1 -foot thick layer of 4- to 6 -inch quarry spalls is used in high traffic areas of the site to
protect the subgrade soil from disturbance.
• Contingencies are included in the project schedule and budget to allow for the above elements.
Structural Fill Materials
General
Material used for structural fill should be free of debris, organic material and rock fragments larger
than 3 inches. The workability of material for use as structural fill will depend on the gradation and
moisture content of the soil. As the amount of fines increases, soil becomes increasingly more
sensitive to small changes in moisture content and adequate compaction becomes more difficult or
impossible to achieve.
On -Site Soil
We anticipate that the majority of the on -site soils encountered during construction will consist of
gravels with sand located at or near the surface of the site. It is our opinion that this material is a
suitable source for structural fill during a significant portion of the year. However, we anticipate that
screening will be needed to remove oversize clasts prior to placement. On -site materials used as
structural fill should be free of roots, organic matter and other deleterious materials and particles larger
than 3 inches in diameter.
Select Granular Fill
Select granular fill should consist of imported, well - graded sand and gravel or crushed rock with a
maximum particle size of 3 inches and less than 5 percent passing a U.S. Standard No. 200 sieve
based on the minus % -inch fraction. Organic matter, debris or other deleterious material should not
be present. In our experience, "gravel borrow" as described in Section 9- 03.14(1) of the 2008 WSDOT
Standard Specifications is typically a suitable source for select granular fill during periods of wet
weather, provided that the percent passing a U.S. Standard No. 200 sieve is less than 5 percent based
on the minus % -inch fraction.
Structural Fill Placement and Compaction
General
Structural fill should be placed on an approved subgrade that consists of uniformly firm and unyielding
inorganic native soils or compacted structural fill. Structural fill should be compacted at a moisture
content near optimum. The optimum moisture content varies with the soil gradation and should be
evaluated during construction.
FILE • 847-004-01 AIM T C8E ®L®GIC, VNC.
Yelm High School Bypass Road
Geotechnical and Groundwater Evaluation Report
August 29, 2017
Structural fill should be placed in uniform, horizontal lifts and uniformly densified with vibratory
compaction equipment. The maximum lift thickness will vary depending on the material and
compaction equipment used, but should generally not exceed the loose thicknesses provided on Table
3. Structural fill materials should be compacted in accordance with the compaction criteria provided
in Table 4.
Table 3. Recommended Uncompacted Lift Thickness
Table 4. Recommended Compaction Criteria in Structural Fill Zones
Percent Maximum Dry Density Determined by
Fill Type ASTM Test Method D 1557 at ±3% of Optimum Moisture
0 to 2 Feet Below > 2 Feet Below pipe Zone
Su bg rade Su bg rade
Imported or On -site Granular, 95 95 -----
Maximum Particle Size < 1 -1/4 -inch
Imported or On -site Granular, N/A (Proof -roll) N/A (Proof -roll) -----
Maximum Particle Size >1 -1/4 -inch
Trench Back-fill' 95 92 90
Note: 'Trench backfill above the pipe zone in nonstructural areas should be compacted to at least 85 percent.
Conventional Retaining Walls
General
We do not anticipate that retaining walls would be utilized for the proposed project. If permanent
slopes are necessary, the following sections provide general guidelines for retaining wall design on
this site. We should be contacted during the design phase to review retaining wall plans and provide
supplemental recommendations, if needed.
Drainage
Positive drainage is imperative behind any retaining structure. This can be accomplished by using a
zone of free - draining material behind the wall with perforated pipes to collect water seepage. The
drainage material should consist of coarse sand and gravel containing less than 5 percent fines based
FILE No. 847 - 004 -01
0
I I T C8E ®L ®GIC, VNC.
Recommended Uncompacted Fill Thickness
Compaction
(inches)
Equipment
Granular Materials
Maximum Particle Size
Granular Materials Maximum Particle Size >
1 Mi
< 1 1/2 inch
1 1/2 inch
Hand Tools (Plate Compactors
4-8
Not Recommended
and Jumping Jacks)
Rubber -tire Equipment
10-12
6-8
Light Roller
10-12
8-10
Heavy Roller
12-18
12-16
Hoe Pack Equipment
18-24
12-16
Note: The above table is intended
to serve as a guideline and should not be included in the project specifications.
Table 4. Recommended Compaction Criteria in Structural Fill Zones
Percent Maximum Dry Density Determined by
Fill Type ASTM Test Method D 1557 at ±3% of Optimum Moisture
0 to 2 Feet Below > 2 Feet Below pipe Zone
Su bg rade Su bg rade
Imported or On -site Granular, 95 95 -----
Maximum Particle Size < 1 -1/4 -inch
Imported or On -site Granular, N/A (Proof -roll) N/A (Proof -roll) -----
Maximum Particle Size >1 -1/4 -inch
Trench Back-fill' 95 92 90
Note: 'Trench backfill above the pipe zone in nonstructural areas should be compacted to at least 85 percent.
Conventional Retaining Walls
General
We do not anticipate that retaining walls would be utilized for the proposed project. If permanent
slopes are necessary, the following sections provide general guidelines for retaining wall design on
this site. We should be contacted during the design phase to review retaining wall plans and provide
supplemental recommendations, if needed.
Drainage
Positive drainage is imperative behind any retaining structure. This can be accomplished by using a
zone of free - draining material behind the wall with perforated pipes to collect water seepage. The
drainage material should consist of coarse sand and gravel containing less than 5 percent fines based
FILE No. 847 - 004 -01
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I I T C8E ®L ®GIC, VNC.
Yelm High School Bypass Road
Geotechnical and Groundwater Evaluation Report
August 29, 2017
on the fraction of material passing the % -inch sieve. The wall drainage zone should extend horizontally
at least 12 inches from the back of the wall. If a stacked block wall is constructed, we recommend
that a barrier such as a non -woven geotextile filter fabric be placed against the back of the wall to
prevent loss of the drainage material through the wall joints.
A perforated smooth - walled rigid PVC pipe, having a minimum diameter of 4 inches, should be placed
at the bottom of the drainage zone along the entire length of the wall. Drainpipes should discharge to
a tightline leading to an appropriate collection and disposal system. An adequate number of cleanouts
should be incorporated into the design of the drains in order to provide access for regular maintenance.
Roof downspouts, perimeter drains or other types of drainage systems should not be connected to
retaining wall drain systems.
Design Parameters
We recommend an active lateral earth pressure of 31 pcf (equivalent fluid density) for a level backfill
condition. This assumes that the top of the wall is not structurally restrained and is free to rotate. For
restrained walls that are fixed against rotation (at -rest condition), an equivalent fluid density of 45 pcf
can be used for the level backfill condition. For seismic conditions, we recommend a uniform lateral
pressure of 14H psf (where H is the height of the wall) be added to the lateral pressures. This seismic
pressure assumes a peak ground acceleration of 0.32 g. Note that if the retaining system is designed
as a braced system but is expected to yield a small amount during a seismic event, the active earth
pressure condition may be assumed and combined with the seismic surcharge.
The recommended earth pressure values do not include the effects of surcharges from surface loads
or structures. If vehicles were operated within one -half the height of the wall, a traffic surcharge should
be added to the wall pressure. The traffic surcharge can be approximated by the equivalent weight of
an additional 2 feet of backfill behind the wall. Other surcharge loads, such as construction equipment,
staging areas and stockpiled fill, should be considered on a case -by -case basis.
Pavement Design Recommendations
We recommend a pavement section for the bypass roadway to consist of the following minimum
compacted thicknesses placed on a properly prepared subgrade: 8 inches of gravel base, 2 inches of
crushed surfacing top course, (CSTC), and 3 inches of commercial asphalt concrete pavement.
Alternatively, the pavement section may consist of 6 inches of asphalt- treated base and 3 inches of
commercial asphalt concrete.
It should be realized that asphaltic pavements are not maintenance free. Our recommended pavement
section represents our minimum recommendation for an average level of performance during a 20-
year design life; therefore, an average level of maintenance will likely be required. A 20 -year pavement
life typically assumes that an overlay will be placed after about 12 years. Thicker asphalt, base and
subbase courses would offer better long -term performance, but would cost more initially. Conversely,
thinner courses would be more susceptible to "alligator" cracking and other failure modes. As such,
pavement design can be considered a compromise between a high initial cost and low maintenance
costs versus a low initial cost and higher maintenance costs.
FILE • . 847-004-01 • I I T GE0L0GIC, VNC.
Yelm High School Bypass Road
Geotechnical and Groundwater Evaluation Report
August 29, 2017
The native subgrade soils are anticipated to consist mostly of gravels and sand with cobbles. Based
on our experience with similar soil types, our analysis is based on a California Bearing Ratio (CBR)
value of 15 percent. These values assume the upper foot of subgrade soils will be compacted to a
minimum of 95 percent of the modified proctor maximum dry density.
We recommend the following regarding asphalt pavement materials and pavement construction
• Subgrade Preparation: Upper 12 inches of pavement subgrade should be proof - rolled and
inspected for deflection. Areas showing more than 'h -inch deflection during proof rolling should
be over excavated and replaced with gravel base.
• Subbase Course: We recommend that the subbase conform to Section 9- 03.10, Gravel Base, of
the 2016 WSDOTiAPWA Standard Specifications for Road, Bridge and Municipal Construction
(Standard Specifications). The Gravel Base shall be placed and compacted in accordance with
Section 4 -02 of the Standard Specifications.
• Base Course: We recommend that the crushed aggregate base course conform to Section 9-
03.9(3), Crushed Surfacing Top Course, (CSTC) of the WSDOT Standard Specifications. The
CSTC shall be placed and compacted in accordance with Section 4 -04 of the Standard
Specifications.
• Asphalt Concrete: We recommend that the asphalt concrete be Commercial Asphalt conforming
to Sections 9 -02 and 9 -03 of the Standard Specifications. We also recommend that the
Commercial Asphalt be placed and compacted in accordance with Section 5 -04 of the Standard
Specifications.
Compaction: All base material should be compacted to at least 95 percent of the maximum dry density
determined in accordance with ASTM D1557. We recommend that asphalt be compacted to a
minimum of 92 percent of the Rice (theoretical maximum) density or 96 percent of Marshall (maximum
laboratory) density.
DUGUMENT REVIEW AND CONSTRUCTION OBSERVATION
We recommend that we be retained to review the portions of the plans and specifications that pertain
to earthwork construction and stormwater infiltration. We recommend that monitoring, testing and
consultation be performed during construction to confirm that the conditions encountered are
consistent with our explorations and our stated design assumptions. Insight Geologic would be
pleased to provide these services upon request.
REFERENCES
International Code Council, "International Building Code ", 2015.
Seismic Compression of As- compacted Fill Soils with Variable Levels of Fines Content and Fines
Plasticity, Department of Civil and Environmental Engineering, University of California, Los
Angeles, July 2004.
Washington State Department of Transportation ( WSDOT), Standard Specifications for Road, Bridge
and Municipal Construction Manual, 2016.
FILE • 847-004-01 I I T GE0L0GIC, VNC.
Yelm High School Bypass Road
Geotechnical and Groundwater Evaluation Report
August 29, 2017
LIMITATIONS
We have prepared this geotechnical and groundwater evaluation report for the exclusive use of J. W.
Morrissette & Associates and their authorized agents for the proposed Yelm High School Bypass Road
project to be located adjacent to Tahoma Boulevard SE in Yelm, Washington.
Within the limitations of scope, schedule and budget, our services have been executed in accordance
with generally accepted practices in the field of geotechnical engineering in this area at the time this
report was prepared. No warranty or other conditions, expressed or implied, should be understood.
Please refer to Attachment D titled "Report Limitations and Guidelines for Use" for additional
information pertaining to use of this report.
We appreciate the opportunity to be of service to you on this project. Please contact us if you have
questions or require additional information.
Respectfully Submitted,
INSIGHT GEOLOGIC, INC.
William E. Halbert, L.E.G., L.HG.
Principal
Attachments
FILE No. 847 - 004 -01 11
FIGURES
INS T GE ®L ®GIC, VNC.
MCKENNA, WASHINGTON
7.5 MINUTE QUADRANGLE
Year1990
SCALE: 1: 24000 YELM HIGH SCHOOL BYPASS ROAD
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APPROXIMATE PROJECT BOUNDARY
SCALE: 1" = 200 YELM HIGH SCHOOL BYPASS ROAD
YELM, WASHINGTON
Figure G
INSIGHT GEOLOGIC, INC.
Site Plan
ATTACHMENT A
EXPLORATION LOGS
INS T GE ®L ®GIC, VNC.
SOIL CLASSIFICATION CHART
MAJOR DIVISIONS
SYMBOLS
GROUP NAME
CC
CEMENT CONCRETE
AC
El
GW
WELL- GRADED GRAVEL,
CRUSHED ROCK/
QUARRY SPALLS
GRAVEL
CLEAN
TOPSOIL /SOD /DUFF
COMPACTION TEST
FINE TO COARSE GRAVEL
PP POCKET PENETROMETER
AND
GRAVEL
SA SIEVE ANALYSIS
DS DIRECT SHEAR
GP
POORLY GRADED GRAVEL
TX TRIAXIAL COMPRESSION
GRAVELLY
<5 % FINES
UC UNCONFINED COMPRESSION
MC MOISTURE CONTENT
SOILS
VS VANE SHEAR
MORE THAN 50%
COARSE
OF COARSE
GRAVEL
GM
SILTY GRAVEL
GRAINED
FRACTION
WITH FINES
GC
CLAYEY GRAVEL
SOILS
RETAINED
ON NO. 4SIEVE
12% FINES
SW
WELL- GRADED SAND,
SAND
CLEAN
FINE TO COARSE SAND
MORE THAN 5o%
RETAINED ON
AND
SAND
NO. 200 SIEVE
SANDY
5% FINES
SP
POORLY GRADED SAND
SOILS
MORE THAN 50%
OF COARSE
SAND
SM
SILTY SAND
FRACTION
WITH FINES
PASSING
NO.4 SIEVE
>12 %FINES
Sc
CLAYEY SAND
SILTS
ML
SILT
AND
INORGANIC
CL
CLAY
FINE
CLAYS
GRAINED
ORGANIC SILT,
SOILS
LIQUID LIMIT
LESS THAN 50
ORGANIC
OL
ORGANIC CLAY
SILT OF HIGH PLASTICITY,
SILTS
MH
MORE THAN 50%
AND
INORGANIC
ELASTIC SILT
CH
CLAY OF HIGH PLASTICITY,
PASSING NO.
200 SIEVE
CLAYS
FAT CLAY
LIQUID LIMIT
��� i
ORGANIC CLAY,
50ORMORE
ORGANIC
�'��
CH
ORGANIC SILT
HIGHLY ORGANIC SOILS
PT
PEAT
70
60
k 50
W
O
Z 40
U
1= 30
cn
Q
a 20
10
0 10 20 30 40 50 60 70 80 90 100
LIQUID LIMIT
SOIL MOISTURE MODIFIERS:
DRY - ABSENCE OF MOISTURE, DUSTY, DRY TO THE TOUCH
MOIST - DAMP, BUT NO VISIBLE WATER
WET - VISIBLE FREE WATER OR SATURATED, USUALLY SOIL IS OBTAINED BELOW WATER TABLE
INSIGHT GEOLOGIC, INC.
ADDITIONAL MATERIAL SYMBOLS
SYMBOLS
TYPICAL DESCRIPTION
CC
CEMENT CONCRETE
AC
ASPHALT CONCRETE
CA CHEMICAL ANALYSIS
CR
CRUSHED ROCK/
QUARRY SPALLS
PM PERMEABILITY OR
TS
TOPSOIL /SOD /DUFF
GROUNDWATER
EXPLORATION SYMBOLS
MEASURED GROUNDWATER LEVEL IN EXPLORATION,
WELL, OR PIEZOMETER
i GROUNDWATER OBSERVED AT TIME OF EXPLORATION
PERCHED WATER OBSERVED AT TIME OF EXPLORATION
MEASURED FREE PRODUCT IN WELL OR PIEZOMETER
STRATIGRAPHIC CONTACT
APPROXIMATE CONTACT BETWEEN SOIL STRATA
OR GEOLOGIC UNIT
- -- APPROXIMATE LOCATION OF SOIL STRATA CHANGE
WITHIN GEOLOGIC SOIL UNIT
APPROXIMATE GRADUAL CHANGE BETWEEN SOIL
STRATA OR GEOLOGIC SOIL UNIT
APPROXIMATE GRADUAL CHANGE OF SOIL STRATA
WITHIN GEOLOGIC SOIL UNIT
LABORATORY/ FIELD
TEST CLASSIFICATIONS
%F PERECENT FINES
MD MOISTURE CONTENT AND
DRY DENSITY
AL ATTERBERG LIMITS
OC ORGANIC COMPOUND
CA CHEMICAL ANALYSIS
PM PERMEABILITY OR
CP LABORATORY
HYDRAULIC CONDUCTIVITY
COMPACTION TEST
PP POCKET PENETROMETER
CS CONSOLIDATION TEST
SA SIEVE ANALYSIS
DS DIRECT SHEAR
TX TRIAXIAL COMPRESSION
HA HYDROMETER ANALYSIS
UC UNCONFINED COMPRESSION
MC MOISTURE CONTENT
VS VANE SHEAR
SAMPLER SYMBOLS
2.4 INCH I.D. SPLIT BARREL ® SHELBY TUBE
DIRECT -PUSH ® PISTON
STANDARD PENETRATION TEST ® BULK OR GRAB
SHEEN CLASSIFICATIONS
NS NOVISIBLESHEEN
SS SLIGHT SHEEN
MS MODERATE SHEEN
HS HEAVY SHEEN
NT NOT TESTED
Key to Exploration Logs
MW -1
=F -° C2 REMARKSAND
w w Sao N LITHOLOGY SOIL DESCRIPTION LABORATORY WELL
TEST RESULTS CONSTRUCTION
0
1
2
3
4
5
6
'
8
9
10
11
12
13
14
15L
1
2
3
4
48/18
48/24
24/36
24/40
Dark brown fine to coarse gravel with fine to medium
sand, loose, dry
Grades to light brown fine to coarse gravel with
cobbles and fine to coarse sand, loose, dry
Grades to medium dense, moist
0)
M
U
>
a
Q
U
p
m
o
0
>
III
IIII
IIII
IIII
IIII
IIII
Groundwater not encounterted
I
LEGEND:
PROJECT NO.: 847 - 004 -01
DATE: AUGUST 4, 2017
TOTAL DEPTH: 12 FEET
DOE WELL NO.: BJM -535
DRILLING CONTRACTOR: STD ENV PROBE
DRILLING EQUIPMENT: GEOPROBE 5410
LOGGED BY: AND YELM HIGH SCHOOL BYPASS ROAD
YELM, WASHINGTON
INSIGHT GEDLflGIC, INC.
Exploration Log MW -1
TR -1
DEPTH REMARKS AND
(FT) U.S.C.S. LITHOLOGY SOIL DESCRIPTION LABORATORY
TEST RESULTS
0
1
2
.3
4
5
�
(D
Brown fine to coarse gravel with fine to medium sand and cobbles, trace
organics, loose, dry
Grades to brown fine to coarse gravel with fine to coarse sand, silt and
cobbles, loose, dry
Grades to light brown fine to coarse gravel and cobbles, loose, moist
6
7
8
9
10
Groundwater not encountered
LEGEND:
PROJECT NO.: 847 - 004 -01
DATE: AUGUST 3, 2017
TOTAL DEPTH: 6 FEET
DRILLING EQUIPMENT: EXCAVATOR
LOGGED BY: ANDREW JOHNSON
YELM HIGH SCHOOL BYPASS ROAD
YELM, WASHINGTON
INSIGHT GEOLoric, INC.
Exploration Log TP -1
TR -2
DEPTH REMARKS AND
(FT) U.S.C.S. LITHOLOGY SOIL DESCRIPTION LABORATORY
TEST RESULTS
0
1
2
.3
4
5
�
Dark brown fine to coarse gravel with fine to coarse sand, trace organics,
loose, dry
Grades to light brown fine to coarse gravel with medium to coarse sand and
cobbles, loose, dry
6
7
8
9
10
Groundwater not encountered
LEGEND:
PROJECT NO.: 847 - 004 -01
DATE: AUGUST 3, 2017
TOTAL DEPTH: 6 FEET
DRILLING EQUIPMENT: EXCAVATOR
LOGGED BY: ANDREW JOHNSON
YELM HIGH SCHOOL BYPASS ROAD
YELM, WASHINGTON
INSIGHT GEOLoric, INC.
Exploration Log TP -2
TR -3
DEPTH REMARKS AND
(FT) U.S.C.S. LITHOLOGY SOIL DESCRIPTION LABORATORY
TEST RESULTS
0
1
2
.3
4
5
�
Dark brown fine to coarse gravel with cobbles, trace sand and organics,
loose, dry
Grades to light brown fine to coarse gravel with cobbles and medium sand,
medium dense, dry
6
7
8
9
10
Groundwater not encountered
LEGEND:
PROJECT NO.: 847 - 004 -01
DATE: AUGUST 3, 2017
TOTAL DEPTH: 6 FEET
DRILLING EQUIPMENT: EXCAVATOR
LOGGED BY: ANDREW JOHNSON
YELM HIGH SCHOOL BYPASS ROAD
YELM, WASHINGTON
INSIGHT GEOLoric, INC.
Exploration Log TP -3
TR -4
DEPTH REMARKS AND
(FT) U.S.C.S. LITHOLOGY SOIL DESCRIPTION LABORATORY
TEST RESULTS
0
1
2
.3
4
5
�
Dark brown fine to coarse gravel with fine to medium sand and cobbles,
trace organics, loose, dry
Grades to light brown fine to coarse gravel with fine to coarse sand, medium
dense, dry
6
7
8
9
10
Groundwater not encountered
LEGEND:
PROJECT NO.: 847 - 004 -01
DATE: AUGUST 3, 2017
TOTAL DEPTH: 6 FEET
DRILLING EQUIPMENT: EXCAVATOR
LOGGED BY: ANDREW JOHNSON
YELM HIGH SCHOOL BYPASS ROAD
YELM, WASHINGTON
INSIGHT GEOLoric, INC.
Exploration Log TP -4
TP -5
DEPTH REMARKS AND
(FT) U.S.C.S. LITHOLOGY SOIL DESCRIPTION LABORATORY
TEST RESULTS
0
Dark brown fine to medium sand, occasional gravel, loose, dry
1 Grades to brown fine to medium sand, loose, moist
2
.3 �
U)
4
5
6
Groundwater not encountered
7
8
9
10
LEGEND:
PROJECT NO.: 847 - 004 -01
DATE: AUGUST 3, 2017
TOTAL DEPTH: 6 FEET
DRILLING EQUIPMENT: EXCAVATOR
LOGGED BY: ANDREW JOHNSON
INSIGHT GEOLoric, INC.
YELM HIGH SCHOOL BYPASS ROAD
YELM, WASHINGTON
Exploration Log TP -5
ATTACHMENT B
WEB SOIL SURVEY
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ATTACHMENT C
LABORATORY ANALYSES RESULTS
INS T GE ®L ®GIC, VNC.
Gradation Analysis Summary Data
Job Name: Yelm High School Bypass Road Sample Location: MW -1
Job Number: 847 - 004 -01 Sample Name: MW -1 10.0' -12.0'
Date Tested: 8/7/17 Depth: 10 - 12 Feet
Tested By: Jessica Christensen
Moisture Content ( %) 2.5%
LL --
PL --
PI - -
D10 0.30
D30 4.80
D60 18.00
D90 32.00
Cc 4.27
Cu 60.00
ASTM Classification
Group Name: Poorly Graded Gravel with Sand
Symbol: GP
INSIGHT GEOLOGIC, INC.
Percent
Percent by
Sieve Size
Passing
Size Fraction
Weight
3.0 in. (75.0)
100.0
Coarse Gravel
36.8
1.5 in. (37.5)
100.0
Fine Gravel
33.4
3/4 in. (19.0)
63.2
3/8 in. (9.5 -mm)
38.0
Coarse Sand
7.0
No. 4 (4.75 -mm)
29.8
Medium Sand
10.1
No. 10 (2.00 -mm)
22.8
Fine Sand
8.7
No. 20 (.850 -mm)
17.8
No. 40 (.425 -mm)
12.7
Fines
4.0
No. 60 (.250 -mm)
8.8
Total
100.0
No. 100 (.150 -mm)
6.3
No. 200 (.075 -mm)
4.0
LL --
PL --
PI - -
D10 0.30
D30 4.80
D60 18.00
D90 32.00
Cc 4.27
Cu 60.00
ASTM Classification
Group Name: Poorly Graded Gravel with Sand
Symbol: GP
INSIGHT GEOLOGIC, INC.
Gradation Analysis Summary Data
Job Name: Yelm High School Bypass Road Sample Location: TP -1
Job Number: 847 - 004 -01 Sample Name: TP -1 2.0' -6.0'
Date Tested: 8/7/17 Depth: 2 - 6 Feet
Tested By: Jessica Christensen
Moisture Content ( %) 2.8%
LL --
PL --
PI - -
D10 0.85
D30 15.00
D6o 46.00
D90 67.00
Cc 5.75
Cu 54.12
ASTM Classification
Group Name: Poorly Graded Gravel
Symbol: GP
INSIGHT GEOLOGIC, INC.
Percent
Percent by
Sieve Size
Passing
Size Fraction
Weight
3.0 in. (75.0)
100.0
Coarse Gravel
62.2
1.5 in. (37.5)
45.0
Fine Gravel
22.4
3/4 in. (19.0)
37.8
3/8 in. (9.5 -mm)
20.8
Coarse Sand
2.1
No. 4 (4.75 -mm)
15.4
Medium Sand
7.1
No. 10 (2.00 -mm)
13.2
Fine Sand
5.2
No. 20 (.850 -mm)
10.2
No. 40 (.425 -mm)
6.1
Fines
0.9
No. 60 (.250 -mm)
3.0
Total
100.0
No. 100 (.150 -mm)
1.6
No. 200 (.075 -mm)
0.9
LL --
PL --
PI - -
D10 0.85
D30 15.00
D6o 46.00
D90 67.00
Cc 5.75
Cu 54.12
ASTM Classification
Group Name: Poorly Graded Gravel
Symbol: GP
INSIGHT GEOLOGIC, INC.
Gradation Analysis Summary Data
Job Name: Yelm High School Bypass Road Sample Location: TP -2
Job Number: 847 - 004 -01 Sample Name: TP -2 1.0' -6.0'
Date Tested: 8/7/17 Depth: 1 - 6 Feet
Tested By: Jessica Christensen
Moisture Content ( %) 2.4%
LL --
PL --
PI - -
D10 0.65
Dap 8.00
D60 18.00
D90 53.00
Cc 5.47
Cu 27.69
ASTM Classification
Group Name: Poorly Graded Gravel with Sand
Symbol: GP
INSIGHT GEOLOGIC, INC.
Percent
Percent by
Sieve Size
Passing
Size Fraction
Weight
3.0 in. (75.0)
100.0
Coarse Gravel
35.9
1.5 in. (37.5)
81.6
Fine Gravel
42.0
3/4 in. (19.0)
64.1
3/8 in. (9.5 -mm)
34.3
Coarse Sand
5.9
No. 4 (4.75 -mm)
22.1
Medium Sand
10.8
No. 10 (2.00 -mm)
16.2
Fine Sand
4.6
No. 20 (.850 -mm)
12.4
No. 40 (.425 -mm)
5.3
Fines
0.8
No. 60 (.250 -mm)
2.2
Total
100.0
No. 100 (.150 -mm)
1.3
No. 200 (.075 -mm)
0.8
LL --
PL --
PI - -
D10 0.65
Dap 8.00
D60 18.00
D90 53.00
Cc 5.47
Cu 27.69
ASTM Classification
Group Name: Poorly Graded Gravel with Sand
Symbol: GP
INSIGHT GEOLOGIC, INC.
Gradation Analysis Summary Data
Job Name: Yelm High School Bypass Road Sample Location: TP -3
Job Number: 847 - 004 -01 Sample Name: TP -3 0.0' -1.0'
Date Tested: 8/7/17 Depth: 0 - 1 Feet
Tested By: Jessica Christensen
Moisture Content ( %) 3.2%
LL --
PL --
PI - -
D10 1.10
D30 40.00
D60 54.00
D90 69.00
Cc 26.94
Cu 49.09
ASTM Classification
Group Name: Poorly Graded Gravel
Symbol: GP
INSIGHT GEOLOGIC, INC.
Percent
Percent by
Sieve Size
Passing
Size Fraction
Weight
3.0 in. (75.0)
100.0
Coarse Gravel
78.2
1.5 in. (37.5)
23.0
Fine Gravel
9.4
3/4 in. (19.0)
21.8
3/8 in. (9.5 -mm)
15.9
Coarse Sand
1.6
No. 4 (4.75 -mm)
12.5
Medium Sand
4.9
No. 10 (2.00 -mm)
10.9
Fine Sand
4.7
No. 20 (.850 -mm)
9.3
No. 40 (.425 -mm)
5.9
Fines
1.2
No. 60 (.250 -mm)
3.2
Total
100.0
No. 100 (.150 -mm)
2.1
No. 200 (.075 -mm)
1.2
LL --
PL --
PI - -
D10 1.10
D30 40.00
D60 54.00
D90 69.00
Cc 26.94
Cu 49.09
ASTM Classification
Group Name: Poorly Graded Gravel
Symbol: GP
INSIGHT GEOLOGIC, INC.
Gradation Analysis Summary Data
Job Name: Yelm High School Bypass Road Sample Location: TP -3
Job Number: 847 - 004 -01 Sample Name: TP -3 1.0' -6.0'
Date Tested: 8/7/17 Depth: 1 - 6 Feet
Tested By: Jessica Christensen
LL --
PL --
PI - -
D10 1.00
D30 14.00
D6o 27.00
D90 45.00
Cc 7.26
Cu 27.00
ASTM Classification
Group Name: Poorly Graded Gravel with Sand
Symbol: GP
INSIGHT GEOLOGIC, INC.
Moisture Content ( %)
2.4%
Percent
Percent by
Sieve Size
Passing
Size Fraction
Weight
3.0 in. (75.0)
100.0
Coarse Gravel
59.2
1.5 in. (37.5)
83.9
Fine Gravel
24.6
3/4 in. (19.0)
40.8
3/8 in. (9.5 -mm)
25.4
Coarse Sand
4.3
No. 4 (4.75 -mm)
16.2
Medium Sand
7.8
No. 10 (2.00 -mm)
11.9
Fine Sand
3.5
No. 20 (.850 -mm)
9.4
No. 40 (.425 -mm)
4.1
Fines
0.6
No. 60 (.250 -mm)
1.6
Total
100.0
No. 100 (.150 -mm)
0.9
No. 200 (.075 -mm)
0.6
LL --
PL --
PI - -
D10 1.00
D30 14.00
D6o 27.00
D90 45.00
Cc 7.26
Cu 27.00
ASTM Classification
Group Name: Poorly Graded Gravel with Sand
Symbol: GP
INSIGHT GEOLOGIC, INC.
Gradation Analysis Summary Data
Job Name: Yelm High School Bypass Road Sample Location: TP -5
Job Number: 847 - 004 -01 Sample Name: TP -5 2.0' -6.0'
Date Tested: 8/7/17 Depth: 2 - 6 Feet
Tested By: Jessica Christensen
Moisture Content ( %)
Percent
Sieve Size Passing
7.3%
Percent by
Size Fraction Weight
3.0 in. (75.0)
100.0
Coarse Gravel
0.0
1.5 in. (37.5)
100.0
Fine Gravel
0.1
3/4 in. (19.0)
100.0
3/8 in. (9.5 -mm)
100.0
Coarse Sand
0.5
No. 4 (4.75 -mm)
99.9
Medium Sand
44.1
No. 10 (2.00 -mm)
99.4
Fine Sand
52.3
No. 20 (.850 -mm)
97.5
No. 40 (.425 -mm)
55.3
Fines
3.0
No. 60 (.250 -mm)
16.5
Total
100.0
No. 100 (.150 -mm)
6.0
No. 200 (.075 -mm)
3.0
LL --
PL --
PI - -
D10 0.20
D30 0.31
D60 0.47
D90 0.61
Cc 1.02
Cu 2.35
ASTM Classification
Group Name: Poorly Graded Sand
Symbol: SP
INSIGHT GEOLOGIC, INC.
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ATTACHMENT D
REPORT LIMITATIONS AND GUIDELINES FOR USE
INS T GE ®L ®GIC, VNC.
ATTACHMENT D
REPORT LIMITATIONS AND GUIDELINES FOR USE'
This attachment provides information to help you manage your risks with respect to the use of this
report.
GEOTECHNICAL SERVICES ARE PERFORMED FOR SPECIFIC PURPOSES, PERSONS
AND PROJECTS
This report has been prepared for the exclusive use of J. W. Morrissette & Associates (Client) and
their authorized agents. This report may be made available to regulatory agencies for review. This
report is not intended for use by others, and the information contained herein is not applicable to other
sites.
Insight Geologic Inc. structures our services to meet the specific needs of our clients. For example, a
geotechnical or geologic study conducted for a civil engineer or architect may not fulfill the needs of a
construction contractor or even another civil engineer or architect that are involved in the same project.
Because each geotechnical or geologic study is unique, each geotechnical engineering or geologic
report is unique, prepared solely for the specific client and project site. Our report is prepared for the
exclusive use of our Client. No other party may rely on the product of our services unless we agree in
advance to such reliance in writing. This is to provide our firm with reasonable protection against open -
ended liability claims by third parties with whom there would otherwise be no contractual limits to their
actions. Within the limitations of scope, schedule and budget, our services have been executed in
accordance with our Agreement with the Client and generally accepted geotechnical practices in this
area at the time this report was prepared. This report should not be applied for any purpose or project
except the one originally contemplated.
A GEOTECHNICAL ENGINEERING OR GEOLOGIC REPORT IS BASED ON A UNIQUE
OF PROJECT - SPECIFIC FACTORS
Insight Geologic, Inc. considered a number of unique, project- specific factors when establishing the
scope of services for this project and report. Unless Insight Geologic specifically indicates otherwise,
do not rely on this report if it 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.
For example, changes that can affect the applicability of this report include those that affect:
• the function of the proposed structure;
• elevation, configuration, location, orientation or weight of the proposed structure;
• composition of the design team; or
• project ownership.
Developed based on material provided by ASFE, Professional Firms Practicing in the Geosciences; www.asfe.org .
INSIGHT GEOLOGIC, INC. LIMITATIONS
If important changes are made after the date of this report, Insight Geologic should be given the
opportunity to review our interpretations and recommendations and provide written modifications or
confirmation, as appropriate.
SUBSURFACE CONDITIONS CAN CHANGE
This geotechnical or geologic report is based on conditions that existed at the time the study was
performed. The findings and conclusions of this report may be affected by the passage of time, by
manmade events such as construction on or adjacent to the site, or by natural events such as floods,
earthquakes, slope instability or ground water fluctuations. Always contact Insight Geologic before
applying a report to determine if it remains applicable.
MOST GEOTECHNICAL AND GEOLOGIC FINDINGS ARE PROFESSIONAL OPINIONS
Our interpretations of subsurface conditions are based on field observations from widely spaced
sampling locations at the site. Site exploration identifies subsurface conditions only at those points
where subsurface tests are conducted or samples are taken. Insight Geologic reviewed field and
laboratory data and then applied our professional judgment to render an opinion about subsurface
conditions throughout the site. Actual subsurface conditions may differ, sometimes significantly, from
those indicated in this report. Our report, conclusions and interpretations should not be construed as
a warranty of the subsurface conditions.
GEOTECHNICAL ENGINEERING REPORT RECOnnnnFNDATIONS ARE NOT FINAL
Do not over -rely on the preliminary construction recommendations included in this report. These
recommendations are not final, because they were developed principally from Insight Geologic's
professional judgment and opinion. Insight Geologic's recommendations can be finalized only by
observing actual subsurface conditions revealed during construction. Insight Geologic cannot assume
responsibility or liability for this report's recommendations if we do not perform construction
observation.
Sufficient monitoring, testing and consultation by Insight Geologic should be provided during
construction to confirm that the conditions encountered are consistent with those indicated by the
explorations, to provide recommendations for design changes should the conditions revealed during
the work differ from those anticipated, and to evaluate whether or not earthwork activities are
completed in accordance with our recommendations. Retaining Insight Geologic for construction
observation for this project is the most effective method of managing the risks associated with
unanticipated conditions.
A GEOTECHNICAL ENGINEERING OR GEOLOGIC REPORT COULD BE SUBJECT TO
MISINTERPRETATION
Misinterpretation of this report by other design team members can result in costly problems. You could
lower that risk by having Insight Geologic confer with appropriate members of the design team after
submitting the report. Also retain Insight Geologic to review pertinent elements of the design team's
plans and specifications. Contractors can also misinterpret a geotechnical engineering or geologic
report. Reduce that risk by having Insight Geologic participate in pre -bid and pre- construction
conferences, and by providing construction observation.
INSIGHT GEOLOGIC, INC. LIMITATIONS
DO NOT REDRAW THE EXPLORATION LOGS
Geotechnical engineers and geologists prepare final boring and testing logs based upon their
interpretation of field logs and laboratory data. To prevent errors or omissions, the logs included in a
geotechnical engineering or geologic 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 believe they can make contractors liable for unanticipated
subsurface conditions by limiting what they provide for bid preparation. To help prevent costly
problems, give contractors the complete geotechnical engineering or geologic 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 Insight Geologic and /or to conduct additional study to obtain the specific types of
information they need or prefer. A pre -bid conference can also be valuable. Be sure contractors have
sufficient time to perform additional study. Only then might an owner be in a position to give contractors
the best information available, while requiring them to at least share the financial responsibilities
stemming from unanticipated conditions. Further, a contingency for unanticipated conditions should
be included in your project budget and schedule.
CONTRACTORS ARE RESPONSIBLE FOR SITE SAFETY ON THEIR OWN
CONSTRUCTION PROJECTS
Our geotechnical recommendations are not intended to direct the contractor's procedures, methods,
schedule or management of the work site. The contractor is solely responsible for job site safety and
for managing construction operations to minimize risks to on -site personnel and to adjacent properties.
READ THESE PROVISIONS CLOSELY
Some clients, design professionals and contractors may not recognize that the geoscience practices
(geotechnical engineering or geology) are far less exact than other engineering and natural science
disciplines. This lack of understanding can create unrealistic expectations that could lead to
disappointments, claims and disputes. Insight Geologic includes these explanatory "limitations"
provisions in our reports to help reduce such risks. Please confer with Insight Geologic if you are
unclear how these "Report Limitations and Guidelines for Use" apply to your project or site.
GEOTECHNICAL, GEOLOGIC AND ENVIRONMENTAL REPORTS SHOULD NOT BE
INTERCHANGED
The equipment, techniques and personnel used to perform an environmental study differ significantly
from those used to perform a geotechnical or geologic study and vice versa. For that reason, a
geotechnical engineering or geologic report does not usually relate any environmental findings,
conclusions or recommendations; e.g., about the likelihood of encountering underground storage
tanks or regulated contaminants. Similarly, environmental reports are not used to address
geotechnical or geologic concerns regarding a specific project.
INSIGHT GEOLOGIC, INC. LIMITATIONS