HomeMy WebLinkAboutSTM Geotech Report SU01378.000-120 - R1.pdf IfirCTL I THOMPSON
INCORPORATED
SOILS AND FOUNDATION INVESTIGATION
STURM RESIDENCE
LOT 2
VAIL MEADOWS, FILING 1
5034 & 5044 MAIN GORE DRIVE SOUTH
VAIL, COLORADO
Prepared For:
Leisa Sturm
4552 Meadow Drive #13
Vail, Colorado 81657
Project No. SU01378.000-120
July 7, 2017
1790 Airport Road, Unit 2, Breckenridge, Colorado 80424
Telephone: 970-453-2047 www.ctlthompson.com
TABLE OF CONTENTS
SCOPE 1
SUMMARY OF CONCLUSIONS 1
SITE CONDITIONS 2
PROPOSED CONSTRUCTION 2
SUBSURFACE CONDITIONS 2
GEOLOGY 3
SITE EARTHWORK 4
Structural Fill 5
FOUNDATIONS 5
SLABS-ON-GRADE 6
FOUNDATION WALLS 8
Foundation Wall Backfill 9
SUBSURFACE DRAINAGE 10
CONCRETE 10
SURFACE DRAINAGE 11
CONSTRUCTION OBSERVATIONS 12
GEOTECHNICAL RISK 13
RADON 13
LIMITATIONS 14
FIGURE 1 —VICINITY MAP
FIGURE 2— LOCATIONS OF EXPLORATORY PITS
FIGURE 3— SUMMARY LOGS OF EXPLORATORY PITS
FIGURES 4 &5 —GRADATION TEST RESULTS
FIGURE 6— FOUNDATION AND UNDERSLAB DRAIN
TABLE I —LABORATORY TEST RESULTS
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SCOPE
This report presents the results of our Soils and Foundation Investigation for
the Sturm Residence on Lot 2, Vail Meadows, Filing 1 in Vail, Colorado. We con-
ducted this investigation to evaluate subsurface conditions at the site and provide
geotechnical engineering recommendations for the proposed residence. Our report
was prepared from data developed during our field exploration, engineering analy-
sis, and experience with similar conditions. This report includes a description of the
subsurface conditions observed in our exploratory pits and presents geotechnical
engineering recommendations for design and construction of the residence founda-
tions, floor systems, and details influenced by the subsoils. The scope was de-
scribed in a Service Agreement (SU-17-0165) dated June 19, 2017.
Recommendations contained in this report were developed based on our un-
derstanding of the planned construction. If plans differ significantly from the descrip-
tions contained in the report, we should be informed so that we determine whether
our recommendations and design criteria are appropriate. A summary of our conclu-
sions is presented below.
SUMMARY OF CONCLUSIONS
1. Subsurface conditions observed in our exploratory pits consisted of
"topsoil" and fill underlain by silty, sandy gravel soils. The maximum
depth explored was 8 feet. Heavy water seepage was observed in the
pits at approximate depths of 2.5 and 5 feet. Seepage should be ex-
pected during foundation excavation.
2. We anticipate that excavations for the new residence will result in natu-
ral sand/gravel being the predominant soil at anticipated foundation el-
evations for the residence. The residence can be constructed on foot-
ing foundations supported by the undisturbed, natural sand/gravel. De-
sign and construction criteria are presented in the report. It is critical
that we observe the excavation to check whether conditions are as an-
ticipated, prior to placing footings.
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3. Surface drainage should be designed to provide for rapid removal of
surface water away from the building.
4. The design and construction criteria for foundations and floor systems
in this report were compiled with the expectation that all other recom-
mendations presented related to surface and subsurface drainage,
landscaping irrigation, backfill compaction, etc. will be incorporated into
the project and that the home owner will maintain the structure, use
prudent irrigation practices and maintain surface drainage. It is critical
that all recommendations in this report are followed.
SITE CONDITIONS
The site is located on the northeast side of Main Gore Drive South between
Meadow Drive and Ute Lane as shown on Figure 1. A duplex currently exists on the
property. The duplex will be demolished prior to construction of the new residence.
The property surrounded by residential development. The ground surface generally
slopes down to the north with about 14 feet of relief across the property. Vegetation
consists of pine and aspen trees, grass and brush.
PROPOSED CONSTRUCTION
The proposed residence will be a three-story structure with a garage in the
lower level. The lower level and garage floors will be slab-on-grade. The lower level
will be partially below grade. Wood and timber frame construction will be used
above grade with cast-in-place concrete foundation walls below grade. Required ex-
cavations are not expected to exceed about 6 feet for foundations. Foundation
loads are expected to be about 1,000 to 3,000 pounds per linear foot of foundation
wall, with maximum column loads of 40 kips or less.
SUBSURFACE CONDITIONS
Subsurface conditions were investigated by observing two exploratory pits at
the approximate locations shown on Figure 2. Subsurface conditions observed in
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the pits were logged by our engineer who obtained samples of the soils during exca-
vation. Graphic logs of the soils observed in the pits are shown on Figure 3.
Man-placed fill was encountered at the surface of TP-1 to a depth of 4 feet.
"Topsoil" was encountered below the fill in TP-1 and at the surface of TP-2. The
thickness of the topsoil layer was 14 inches in TP-1 and 30 inches in TP-2. Below
the topsoil, we encountered silty sand and gravel soils to the depth explored of 8
feet in both pits. Heavy water seepage was observed in TP-1 at a depth of about 5
feet and in TP-2 at an approximate depth of 2.5 feet. The pits were backfilled after
excavation operations were completed.
Samples obtained in the field were returned to our laboratory where field clas-
sifications were checked and samples were selected for pertinent testing. Gradation
test results of the natural sand and gravel soils are presented on Figures 4 and 5.
Laboratory test results are summarized on Table I.
GEOLOGY
We reviewed the following geologic mapping showing the site.
1. Geologic Map of the Vail East Quadrangle, Eagle County, Colorado
(Map MF-2375) by Karl S. Kellogg, Bruce Bryant and Margaret H. Red-
steer with the U.S. Geological Survey, 2003.
The site is mapped as Pinedale till. Our field investigation and observations
at the site generally support the mapping. We did not observe geologic constraints
on this site that would inhibit the planned construction.
It is critical that all recommendations in this report are followed to increase the
chances that the foundations and slabs-on-grade will perform satisfactorily. After
construction, the homeowner must assume responsibility for maintaining structures
and use appropriate practices regarding drainage and landscaping.
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SITE EARTHWORK
Our subsurface information indicates that excavations for the residence will
be mostly in sand and gravel soils. We should observe the excavation to confirm
whether subsurface conditions are as anticipated. We anticipate excavation of the
soils can be accomplished using conventional, heavy duty excavating equipment.
Hard cobbles and boulders should be expected. Some boulders may be large. A
hydraulic hammer chisel (excavator attachment) or similar device may be required to
split large boulders. Sides of excavations need to be sloped to meet local, state and
federal safety regulations. The onsite soils will likely classify as Type C soils based
on OSHA standards governing excavations. Temporary slopes deeper than 4 feet
that are not retained should be no steeper than 1.5 to 1 (horizontal to vertical) in
Type C soils. Some sloughing of the excavation face may occur as the soils dry out.
Contractors should identify the soils encountered and ensure that applicable stand-
ards are met. Contractors are responsible for site safety and maintenance of the
work site.
Heavy water seepage was observed in the pits, as noted in SUBSURFACE
CONDITIONS. Water seepage should be expected during excavation. The footing
areas should be protected from any seepage and precipitation through the use of
shallow trenches and sumps. Trenches should be 1 to 2 feet below footing sub-
grade elevation. Excavations should be sloped to a gravity discharge or to a tempo-
rary sump where water can be removed by pumping, if necessary. It is very im-
portant that an excavation dewatering plan be in place prior to excavation. If the
footing subgrade soils are exposed without proper drainage and become softened
due to equipment traffic, subexcavation and replacement may be required. This pro-
cess can be costly. We can provide additional recommendations at the time of con-
struction.
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Structural Fill
We do not anticipate that structural fill will be needed below foundations.
However, removal of boulders or existing foundations may require placement of
structural fill to re-establish subgrade elevation. The on-site sand and gravel soils,
free of organic matter, debris and rocks larger than 6 inches in diameter, can be
used as structural fill. It may be necessary to use a clean 2- to 4-inch stone beneath
footing areas if very moist conditions exist. We can evaluate potential fill materials
upon request. Lean-mix concrete (flowable fill) could also be used to fill voids.
The onsite soils with higher levels of silt or clay are moisture sensitive and it
may be difficult to achieve proper compaction. Proper moisture content and pro-
cessing is imperative to attain suitable compaction levels and reduce potential settle-
ment.
Structural fill should be placed in thin loose lifts, moisture conditioned to
within +/-2 percent of optimum moisture content, and compacted to at least 98 per-
cent of ASTM D 698 maximum dry density. Moisture content and density of struc-
tural fill should be tested by a representative of our firm during placement.
FOUNDATIONS
The residence can be supported on footing foundations on the undisturbed,
natural sand and gravel soils. Any existing fill or foundation elements from the exist-
ing residence should be removed beneath footing and slab areas. Prior to concrete
placement, the footing areas should be moistened and compacted to provide a flat
and level subgrade. Loose and disturbed soils should be removed or compacted.
Structural fill, if required, should be tested by our representative and meet the crite-
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ria in the Structural Fill section. Our representative should observe conditions ex-
posed in the completed foundation excavation to confirm whether the exposed soils
are as anticipated and suitable for support of the foundation as designed.
1. The proposed residence can be supported by footing foundations sup-
ported on the undisturbed, natural sand/gravel soils. Soils loosened
during the forming process for the footings should be removed or re-
compacted prior to placing concrete.
2. Footings can be sized using a maximum allowable soil pressure of
3,000 psf. Based on our experience in the area, we expect settlement
of footings designed and constructed as discussed will be approxi-
mately 1 inch or less.
3. To resist lateral loads, a coefficient of friction of 0.40 can be used for
concrete in contact with soil. Lateral loads can be resolved by evaluat-
ing passive resistance using an equivalent fluid density of 400 pcf for
sand and gravel backfill that is compacted to the criteria in Foundation
Wall Backfill and will not be removed. These values have not been
factored; appropriate factors of safety should be applied in design.
4. Continuous wall footings should have a minimum width of at least 16
inches. Foundations for isolated columns should have minimum di-
mensions of 24 inches by 24 inches. Larger sizes may be required,
depending upon foundation loads.
5. Grade beams and foundation walls should be well reinforced, top and
bottom, to span undisclosed loose or soft soil pockets and resist lateral
earth pressures. We recommend reinforcement sufficient to span an
unsupported distance of at least 10 feet. Reinforcement should be de-
signed by the structural engineer.
6. The soils under exterior footings should be protected from freezing.
We recommend the bottom of footings be constructed at a depth of at
least 40 inches below finished exterior grade.
SLABS-ON-GRADE
Slab-on-grade lower level and garage floors are desired. Based on our labor-
atory test data and experience, we judge natural sand and gravel soils suitable to
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support lightly loaded slab-on-grade construction. Fill placed to attain subgrade ele-
vations below floor slabs should be placed in accordance with the recommendations
outlined in Structural Fill. We recommend the following precautions for slab-on-
grade construction at this site. These precautions will not prevent movement from
occurring; they tend to reduce damage if slab movement occurs.
1. Slabs should be separated from exterior walls and interior bearing
members with slip joints which allow free vertical movement of the
slabs.
2. Underslab plumbing should be pressure tested for leaks before the
slabs are constructed. Plumbing and utilities which pass through slabs
should be isolated from the slabs with sleeves and provided with flexi-
ble couplings.
3. Frequent control joints should be provided, in accordance with Ameri-
can Concrete Institute (ACI) recommendations, to reduce problems as-
sociated with shrinkage and curling.
4. We recommend a 4-inch layer of clean gravel be placed beneath the
slabs to provide a flat, uniform subgrade. This material should consist
of minus 2 inch aggregate with at least 50% retained on the No. 4
sieve and less than 2% passing the No. 200 sieve. To prevent water
from collecting below the slabs, the underslab gravel should be con-
nected to the perimeter underdrain system on the downhill side of the
building. Typically this can be accomplished at the lower level frost
wall footing step. We can provide additional recommendations for
drain system layout upon request.
5. The 2015 International Residential Code (IRC R506) states that a 4-
inch base course layer consisting of clean graded sand, gravel,
crushed stone or crushed blast furnace slag shall be placed beneath
below grade floors (unless the underlying soils are free-draining),
along with a vapor retarder.
IRC states that the vapor retarder can be omitted where approved by
the building official. The merits of installation of a vapor retarder below
floor slabs depend on the sensitivity of floor coverings and building use
to moisture. A properly installed vapor retarder is more beneficial be-
low concrete slab-on-grade floors where floor coverings, painted floor
surfaces, or products stored on the floor will be sensitive to moisture.
The vapor retarder is most effective when concrete is placed directly
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on top of it, rather than placing a sand or gravel leveling course be-
tween the vapor retarder and the floor slab. Placement of concrete on
the vapor retarder may increase the risk of shrinkage cracking and
curling. Use of concrete with reduced shrinkage characteristics includ-
ing minimized water content, maximized coarse aggregate content,
and reasonably low slump will reduce the risk of shrinkage cracking
and curling. Considerations and recommendations for the installation
of vapor retarders below concrete slabs are outlined in Section 3.2.3 of
the 2006 American Concrete Institute (ACI) Committee 302, "Guide for
Concrete Floor and Slab Construction (ACI 302.R-96)".
FOUNDATION WALLS
Foundation walls which extend below-grade should be designed for lateral
earth pressures where backfill is not present to about the same extent on both sides
of the wall. Many factors affect the values of the design lateral earth pressure.
These factors include, but are not limited to, the type, compaction, slope and drain-
age of the backfill, and the rigidity of the wall against rotation and deflection. For a
very rigid wall where negligible or very little deflection will occur, an "at-rest" lateral
earth pressure should be used in design. For walls that can deflect or rotate 0.5 to 1
percent of wall height (depending upon the backfill types), lower "active" lateral earth
pressures are appropriate. Our experience indicates typical below-grade walls in
residences deflect or rotate slightly under normal design loads, and that this deflec-
tion results in satisfactory wall performance. Thus, the earth pressures on the walls
will likely be between the "active" and "at-rest" conditions.
If on-site natural sand and gravel soils are used as backfill and the backfill is
not saturated, we recommend design of basement walls at this site using an equiva-
lent fluid density of at least 52 pcf. This value assumes deflection; some minor
cracking of walls may occur. If very little wall deflection is desired, a higher design
value is appropriate. The existing fill soils at the site should not be used for backfill
beneath slab or pavement areas.
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Retaining walls that are free to rotate and allow the active earth pressure con-
dition to develop can be designed using an equivalent fluid density of at least 42 pcf
for on-site sand and gravel soil backfill. The structural engineer should also con-
sider site-specific grade restrictions, the effects of large openings on the behavior of
the walls, and the need for lateral bracing during backfill.
Foundation Wall Backfill
Proper placement and compaction of foundation backfill is important to re-
duce infiltration of surface water and settlement of backfill. The natural sand and
gravel soils can be used as backfill, provided they are free of rocks larger than 6
inches in diameter, organics, and debris. The upper 2 feet of fill should be a rela-
tively impervious material to limit infiltration. Backfill should be placed in thin loose
lifts, moisture conditioned to within +/-2 percent of optimum moisture content, and
compacted to at least 95 percent of ASTM D 698 maximum dry density. Backfill in
landscape areas should be compacted to at least 90 percent of ASTM D 698 maxi-
mum dry density. Thickness of lifts will likely need to be reduced if there are small
confined areas of backfill, which limit the size and weight of compaction equipment.
Some settlement of the backfill should be expected even if the material is placed
and compacted properly. In our experience, settlement of properly compacted back-
fill could be on the order of 0.5 to 1 percent of backfill thickness. Methods to reduce
the risk of backfill settlement include conducting observation and testing during
placement, using a granular material, and increasing the minimum compaction level.
Moisture content and density of the backfill should be tested during placement by a
representative of our firm. Observation of the compaction procedure is necessary.
Testing without observation can lead to undesirable performance.
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SUBSURFACE DRAINAGE
Water from snow melt, precipitation and surface irrigation of lawns and land-
scaping frequently flows through relatively permeable backfill placed adjacent to a
residence, and collects on the surface of less permeable soils occurring at the bot-
tom of foundation excavations. This process can cause wet or moist basement con-
ditions after construction. To reduce the likelihood water pressure will develop out-
side foundation walls and the risk of accumulation of water at the lower level, we
recommend a foundation drain be installed. The drain should be installed along the
entire building perimeter. The foundation drain will not prevent moist conditions in
the lower level.
The drain should consist of a 4-inch diameter, perforated or slotted pipe en-
cased in free-draining gravel, and a geocomposite drain board or clean gravel layer
extending to within 2 feet of exterior grade, adjacent to the walls. The drain should
lead to a positive gravity outlet or sump where water can be removed by pumping.
We recommend two gravity outlets be provided. Sump pumps and gravity outlet lo-
cations must be maintained by the homeowner. A typical foundation drain detail is
presented on Figure 6.
CONCRETE
Concrete in contact with soil can be subject to sulfate attack. We measured
the water-soluble sulfate concentration in a sample taken from the site at less than
0.01 percent. For this level of sulfate concentration, ACI 318-08 Code Require-
ments for Structural Concrete indicates there are no special requirements for sulfate
resistance.
Superficial damage may occur to the exposed surfaces of highly permeable
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concrete, even though sulfate levels are relatively low. To control this risk and to re-
sist freeze-thaw deterioration, the water-to-cementitious materials ratio should not
exceed 0.50 for concrete in contact with soils that are likely to stay moist due to sur-
face drainage or high water tables. Concrete should have a total air content of 6
percent ± 1.5 percent. We advocate all foundation walls and grade beams in con-
tact with the subsoils (including the inside and outside faces of garage and
crawlspace grade beams) be damp-proofed.
SURFACE DRAINAGE
Surface drainage is critical to the performance of foundations, floor slabs and
concrete flatwork. Recommendations in this report are based on effective drainage
for the life of the structure and cannot be relied upon if effective drainage is not
maintained. We recommend the following precautions be observed during construc-
tion and maintained at all times after construction is completed:
1. The ground surface surrounding the exterior of the building should be
sloped to drain away from the building in all directions. We recom-
mend providing a slope of at least 12 inches in the first 10 feet in land-
scape areas. There are instances where this slope cannot be
achieved. A slope of 6 inches in the first 10 feet should be used as a
minimum. We recommend a slope of at least 3 inches in the first 10
feet in paved areas. A swale should be provided around the uphill side
of the building to divert surface runoff.
2. Backfill around the exterior of foundation walls should be placed as de-
scribed in Foundation Wall Backfill. Increases in the moisture content
of the backfill soils after placement often results in settlement. Settle-
ment is most common adjacent to north facing walls. Re-establishing
proper slopes (homeowner maintenance) away from the building may
be necessary.
3. Landscaping should be carefully designed to minimize irrigation.
Plants used near foundation walls should be limited to those with low
moisture requirements; irrigated grass should not be located within 5
feet of the foundation. Sprinklers should not discharge within 5 feet of
the foundation and should be directed away from the building.
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4. Impervious plastic membranes should not be used to cover the ground
surface immediately surrounding the building. These membranes tend
to trap moisture and prevent normal evaporation from occurring. Geo-
textile fabrics can be used to control weed growth and allow some
evaporation to occur.
5. Roof downspouts and drains should discharge well beyond the limits of
all backfill. Splash blocks and/or extensions should be provided at all
downspouts so water discharges onto the ground beyond the backfill.
We generally recommend against burial of downspout discharge.
Where it is necessary to bury downspout discharge, solid, rigid pipe
should be used and it should slope to an open gravity outlet. Buried
downspout discharge pipes should be heated (with thermostat) during
winter months to prevent freezing. Downspout extensions, splash
blocks and buried outlets must be maintained by the homeowner.
6. The design and construction criteria for foundations and floor systems
were compiled with the expectation that all other recommendations
presented in this report related to surface and subsurface drainage,
landscaping irrigation, backfill compaction, etc. will be incorporated into
the project. It is critical that all recommendations in this report are fol-
lowed.
CONSTRUCTION OBSERVATIONS
This report has been prepared for the exclusive use of Leisa Sturm and the
design/construction team for the purpose of providing geotechnical design and con-
struction criteria for the proposed project. The information, conclusions, and recom-
mendations presented herein are based upon consideration of many factors includ-
ing, but not limited to, the type of structure proposed, the geologic setting, and the
subsurface conditions encountered. The conclusions and recommendations con-
tained in the report are not valid for use by others. Standards of practice evolve in
the area of geotechnical engineering. The recommendations provided in this report
are appropriate for about three years. If the proposed project is not constructed
within about three years, we should be contacted to determine if we should update
this report.
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We recommend that CTL I Thompson, Inc. provide construction observation
services to allow us the opportunity to verify whether soil conditions are consistent
with those found during this investigation. If others perform these observations, they
must accept responsibility to judge whether the recommendations in this report re-
main appropriate.
GEOTECHNICAL RISK
The concept of risk is an important aspect with any geotechnical evaluation
primarily because the methods used to develop geotechnical recommendations do
not comprise an exact science. We never have complete knowledge of subsurface
conditions. Our analysis must be tempered with engineering judgment and experi-
ence. Therefore, the recommendations presented in any geotechnical evaluation
should not be considered risk-free. Our recommendations represent our judgment
of those measures that are necessary to increase the chances that the structure will
perform satisfactorily. It is critical that all recommendations in this report are fol-
lowed during construction. The homeowner must assume responsibility for main-
taining the structure and use appropriate practices regarding drainage and land-
scaping. Improvements performed by the owner after construction, such as finishing
a basement or construction of additions, retaining walls, decks, patios, landscaping
and exterior flatwork, should be completed in accordance with recommendations in
this report.
RADON
Radon is a gaseous, radioactive element that comes from the radioactive de-
cay of uranium, which is commonly found in igneous rocks. The average indoor ra-
don level in the Vail area is above the recommended action level of 4 pCi/L as rec-
ommended by the Environmental Protection Agency (http://county-ra-
don.info/CO/Eagle.html). Testing for radon gas at the site is beyond the scope of
this study. Due to the many factors that affect the radon levels in a specific building,
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accurate testing of radon levels is usually only possible after construction is com-
plete. Typically, radon mitigation systems in this area consist of ventilation systems
installed beneath lower level slabs and crawlspaces. The infrastructure for such a
mitigation system can normally be installed during construction at a relatively low
cost, which is recommended. The building should be tested for radon once con-
struction is complete. If test results indicate mitigation is required, the installed sys-
tem can then be used for mitigation. We are not experts in radon testing or mitiga-
tion. If the client is concerned about radon, then a professional in this special field of
practice should be consulted.
LIMITATIONS
Our exploratory pits were located to provide a reasonably accurate picture of
subsurface conditions. Variations in the subsurface conditions not indicated by the
pits will occur. A representative of our firm should observe placement of and test
structural fill. We should observe the completed foundation excavation to confirm
that the exposed soils are suitable for support of the footings as designed. This in-
vestigation was conducted in a manner consistent with that level of care and skill or-
dinarily exercised by geotechnical engineers currently practicing under similar condi-
tions in the locality of this project. No warranty, express or implied, is made. If we
can be of further service in discussing the contents of this report, please call.
CTL I THOMPS6N, IN ,r" x-,�'nQy .;,00,Pi N-
Reviewed by: sir °.� ,
4 4474;70,),,A4
George Benecke II-I, °.-• '"'/,'sy
Division Manager, Sum ,,r�0 �anty,�,o ` , t,,
cc: mk a@evodomus.com
Isturm(cx�computervoice.com
pstu rm(a�computervoice.com
LEISA STURM 14
STURM RESIDENCE
LOT 2,VAIL MEADOWS,FILING 1
CTL I THOMPSON PROJECT NO.SU01378.000-120
C:\Users\gbeneckelAppData\Local\Box\Box Edit\Documents\Yw9YmOW4yUW3tijZiVZEAA==\SU01378.000-120 R1-Sturm Residence.docx
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VICINITY MAP
Project No. SU01378-120 Figure 1
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Scale: 1 inch = 30 feet
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LOCATIONS OF EXPLORATORY PITS
Project No. SU01378-120 Figure 2
m
TP-1 TP-2
ELEV.=8,591 ELEV.=8,595
8,595 ,,_ 8,595
PAW
MOW
AAMA
AWA
ANNA
AMAA
Lower level Top of Slab P� MC=17.3
Elev. = 8,590' +4=42
8,590 �>! ' -200=12 8,590
•, MC=5.6aT
-200=13 � o
p J LL=NP R o
PI=NP 3
s®
AWA
MAMo
a) ''
W 8,585 r'al MC=20.2 8,585 a)
ill
+400=30
-2 =18
LL=27
PI=4
8,580 8,580
LEGEND:
TOPSOIL; silty sand, with roots and organics, moist, dark brown to black. (OL)
FILL; SAND; silty, fine to medium—grained, wood, lenses of clean sand, loose, moist, light
►� brown to brown
SAND and GRAVEL; silty, with subangular cobbles up to 10", more gravel with depth, very
� moist to wet, medium dense to dense, red—brown. (SM—GM)
j-> Heavy water seepage encountered in pit at depth indicated.
Relatively undisturbed hand—driven sample.
Disturbed bulk sample.
NOTES:
1. The pits were excavated with a track—mounted mini excavator on June 27, 2017.
2. Free water levels shown above were observed at the time and under the conditions indicated.
Groundwater levels can fluctuate.
3. Pit locations as shown on Figure 2 were measured from site features and should be considered
approximate.
4. Pit elevations shown were measured by instrument level and are based on a temporary benchmark
as shown on Figure 2
5. These exploratory pits are subject to the explanations, limitations and conclusions contained in this
report.
SUMMARY LOGS OF EXPLORATORY PITS
Project No. SU01378-120 Figure 3
_. _..MOWN---
--
MAIM
HYDROMETER ANALYSIS I SIEVE ANALYSIS
25 HR. 7 HR. TIME READINGS U.S.STANDARD SERIES CLEAR SQUARE OPENINGS
45 MIN. 15 MIN. 60 MIN. 19 MIN. 4 MIN. 1 MIN. '200 `100 *50 *40 *30 *16 *10`8 *4 3/8" 3/4" 1'/:" 3" 5"6" 8"
100 0
i -
I i
90 i i 10
80 20
z70 ' 30 0< 60 - 4011-=:11-1
i H
wj 50 i 50 U
i I Ui
a 40 I 60 a
30 70
I i
20 80
10 90
•
•
0 , , ,, 100
.001 .005 .009 .019 .037 .074 .149 .297 .590 1.19 2.0 2.38 4.76 9.52 19.1 38.1 76.2 127 20u
0.42 152
DIAMETER OF PARTICLE IN MILLIMETERS
SANDS GRAVEL
CLAY(PLASTIC)TO SILT(NON-PLASTIC)
FINE I MEDIUM COARSE FINE I COARSE COBBLES
Sieve Size % Passing
3 in. 100
2 in. 98
1.5 in. 94
3/4 in. 87
1/2 in. 82
3/8 in. 79
No. 4 70
No. 8 63
No. 16 53
No. 30 42
No. 50 28
No. 100 21
No. 200 18
Curve No. 1
Sample of SAND;silty,gravelly(SM) GRAVEL(USCS) 30 % SAND(USCS) 52 %
SILT&CLAY 18 % LIQUID LIMIT 27 %
From TP-1 @ 6.5-7.5' PLASTICITY INDEX 4
Gradation
Test Results
CTLIT PROJECT NO. SU01378-120 Figure 4
•11.11111 '
Rue_ ,
HYDROMETER ANALYSIS I SIEVE ANALYSIS
25 HR. 7 HR. TIME READINGS U.S.STANDARD SERIES CLEAR SQUARE OPENINGS
45 MIN. 15 MIN. 60 MIN. 19 MIN. 4 MIN. 1 MIN. *200 *100 *50 *40 *30 *16 *10*8 *4 3/8" 3/4" 1Y." 3" 5"6" 8"
100 - - . 0
90 — F- 10
80
1 20
. r
070 300
z ._
z
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co _
60 , -
40 H w
a
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z . Z
50 50 w
0 0
cc cc
w ,
O4 w
40 ! 60 °-
3070
._
20 i 80
! 1
10 90
0 100
.001 .005 .009 .019 .037 .074 .149 .297 .590 1.19 2.0 2.38 4.76 9.52 19.1 38.1 76.2 127 20u
0.42 152
DIAMETER OF PARTICLE IN MILLIMETERS
SANDS GRAVEL
CLAY(PLASTIC)TO SILT(NON-PLASTIC)
FINE MEDIUM COARSE FINE COARSE COBBLES
Sieve Size % Passing
3 in. 100
2 in. 95
1.5 in. 92
3/4 in. 80
1/2 in. 73
3/8 in. 69
No. 4 58
No. 8 51
No. 16 41
No. 30 31
No. 50 21
No. 100 14
No. 200 12
Curve No. 1
Sample of SAND&GRAVEL; silty(SM) GRAVEL(USCS) 42 % SAND(USCS) 46 %
SILT&CLAY 12 % LIQUID LIMIT %
From TP-2 @ 4-5PLASTICITY INDEX %
Gradation
Test Results
CTLIT PROJECT NO. SU01378-120 Figure 5
............... ..
...................
..................
.................
SLOPE
PER REPORT •
GEOCOMPOSITE WALL DRAIN OR
12 INCHES OF DRAIN GRAVEL.
EXTEND TO WITHIN 1 TO 2 FEET / BELOW-GRADE WALL
OF FINISH GRADE. DO NOT �
EXTEND TO GROUND SURFACE
BACKFILL
SLOPE
OR BRACE DRAIN GRAVEL SHOULD
PER EXTEND AT LEAST 6
OSHA INCHES ABOVE TOP OF
FOOTING AND ABOVE ANY VAPOR RETARDER
SEEPAGE OBSERVED IN RECOMMENDED BY IRC.
THE CUT SLOPE.
SEEPAGE ':::
1/:y/••/••••••••••••••/a/:•/•�/•y/•,�/, 7-SLIP JOINT
(IF ENCOUNTERED) i!.•..•/.t,/.•I.1/.•/.•I.•/t•L i. �. ;I
,i/.•..•..•..e/.•/.•..i!t•/.•6" MIN
'�I.•I.utit'v�i.�..•/te,t.•..•/`e,tt�!%tigt �:.•: •::r::ii i:i,:. :SLAB-ON-GRADE ::::
N •;!••!•ettNtivitt•!••�•tt;i;:;ri;;ii; ii:::::i:ii:i:::i::::i f• • • •4gA •.•r1 01.1 I`I e
•ip.•.••.. .•/••/.•/ •/••/ . . . ::. ::::.::::::::::::::•• • •g • 1 Iy• • I • • f.I 1
COVER ENTIRE WIDTH OF • '!••••N••••N•M•N••I•Vit,::::::; •:::: ::::::::::::::::: q r,r.►s s .rs.:
GRAVEL WITH NON_WOVEN •!.y/.•.tit tot. .. ..•n•rsi::.::. ::::::::. :::::: :::::::::: r!�:�a•a!yr� „le?,
GEOTEXTILE FABRIC MIRAFI • • �, • •„• • e,,.%�::::.::.:::.:::::.::::::•:::::.
i. /••pv/• .. Itit• /• i • I,=1 1 1'I I /1'I 1 I�'I-1'1
1„ • • 1 • • • ;• s s •
140N OR EQUIVALENT). ;•..•Lr;.••I••I•i/••I•r- �-'• LATERAL DRAIN
ROOFING FELT IS AN •/••''•/'•/'•/'•/” (SEE REPORT)
ACCEPTABLE ALTERNATIVE. �!��/••!•���•�%` 12" MINIMUM •'-••'-•-_•--•~-•e-•=•-•-_
�. l•:ve•` FOOTING
12" MIN.
OR BEYOND
1:1 SLOPE FROM
BOTTOM OF FOOTING
(WHICHEVER IS GREATER).
4-INCH DIAMETER PERFORATED DRAIN PIPE. THE
PIPE SHOULD BE PLACED IN A TRENCH WITH A
SLOPE OF AT LEAST 1/8-INCH DROP PER FOOT
OF DRAIN.
ENCASE PIPE IN 1/2" TO 1-1/2"
WASHED GRAVEL. EXTEND GRAVEL TO
AT LEAST 6" ABOVE FOOTING. FILL
ENTIRE TRENCH WITH GRAVEL.
NOTE:
THE BOTTOM OF THE EXTERIOR DRAIN SHOULD BE AT LEAST 12 INCHES BELOW BOTTOM OF
FOOTING (AND 24 INCHES BELOW TOP OF ADJACENT SLAB OR CRAWLSPACE GRADE) AT THE
HIGHEST POINT. THE UNDERSLAB (LATERAL) DRAINPIPES SHOULD BE AT LEAST 18 INCHES BELOW
TOP OF SLAB. ALL DRAINPIPES SHOULD SLOPE DOWNWARD TO A POSITIVE GRAVITY OUTLET OR TO
A SUMP WHERE WATER CAN BE REMOVED BY PUMPING. WE RECOMMEND TWO GRAVITY OUTLETS
BE PROVIDED. CTL SHOULD BE CONTACTED DURING CONSTRUCTION FOR ADDITIONAL
RECOMMENDATIONS. FOUNDATION AND UNDERSLAB DRAIN
Project No. SU01378-120 Figure 6
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