HomeMy WebLinkAboutVAIL VILLAGE FILING 5 BLOCK 2 LOT E TIVOLI LODGE_017 LEGAL.pdfI
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c&Btecrt Hcpworth-l'awlak Ocotechnical, lnc.
5020 County Rold l5.l
(llenwrxrd Springs. Cokrrado ll l (r0l
Phonc: 970-9{5-79tllt
l-ax: 97(f-945-t1454
hpgeo@ hpgcotech,conr
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I SUBSOIL STUDY
FOR FOUNDATION DESIGN
I pRoposEDTrvoLrLoDGE - ./ 3S6IIANSON RANCH ROAD
I ual., coLoRADo
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JOB NO. r02 672
ocToBER 31,2002
PREPARED FOR:
BOB I-AZIER
386 TIANSON RANCH ROAD
VAIL. COLORADO 81657
I
t,HEPWORTH . PAWLAK GEOTECHNICAL, INC.
October 3I,2OO2
Bob Lazier
386 Hanson Ranch Road
Vail, Colorado 81657 Job No. L02 672
Subject: Report Transmittal, Subsoil Study for Foundation Design, Proposed
Tivoli Lodge, Vail, Colorado
Dear Mr. Lazier:
As requested, we have conducted a subsoil study for the proposed lodge at the subject
site.
Subsurface conditions encountered in the exploratory borings drilled in the proposed
building area, below a shallow clayey fill and topsoil depth, consist of up to 2th feelof
loose to medium dense silty sand overlying relatively dense, slightly silty sandy gravel
containing cobbles and boulders to the maximum explored depth of L7 feet.
Approximately 4 inches of asphalt overlies the fill at Boring 4. Groundwater was not
encountered in the borings and the subsoils were moist.
The proposed lodge can be founded on spread footings placed on the natural coarse
granular subsoils and designed for an allowable bearing pressure in the range of 4,000
to 6,000 psf.
The report which follows describes our exploration, summarizes our findings, and
presents our recommendations. It is important that we provide consultation during
design, and field services during construction to review and monitor the implementation
of the geotechnical recommendations.
,
If you have any questions regarding this report, please contact us.
Sincerely,
HEPWORTH - PAWLAK GEOTECHNICAL. INC.I O,*,e e{tq
Trevor L. Knell
Rev. by: SLP
TLIVksw
TABLE OF CONTENTS
PURPOSE AND SCOPE OF STUDY
PROPOSED CONSTRUCTION . .... 1
SITE CONDITIONS ... . . . .. 2
FIELD EXPLORATION . . .... .. ... 2
SUBSURFACE CONDITIONS ... .,... .... 2
DESIGN RECOMMENDATIONS ...... ... 3
FOUNDATTONS ... ... .. ... 3
FOUNDATIONANDRETAININGWALLS .......4
FLOORSLABS ......6
UNDERDRAIN SYSTEM .... 6
SURFACE DRAINAGE ..... . 7
LIMITATIONS .... ........ 7
FIGURE 1 - LOCATION OF EXPLORATORY BORINGS
FIGURE 2 - LOGS OF EXPLORATORY BORINGS
FIGURE 3 - LEGEND AND NOTES
FIGURE 4 - GRADATION TEST RESULTS
TABLE I - SUMMARY OF LABORATORY TEST RESULTS
H-P GEOTECH
PURPOSE AND SCOPE OF STUDY
This report presents the results of a subsoil study for a proposed lodge to be
located at 386 Hanson Ranch Road, Vail, Colorado. The project site is shown on Fig. 1.
The purpose of the study was to develop recommendations for the foundation design.
The study was conducted in accordance with our agreement for geotechnical
engineering services to you dated October 9,2002.
A field exploration program consisting of exploratory borings was conducted to
obtain information on subsurface conditions. Samples of the subsoils obtained during
the field exploration were tested in the Iaboratory to determine their classification and
other engineering characteristics. The results of the field exploration and laboratory
testing were analyzed to develop recommendations for foundation types, depths and
allowable pressures for the proposed building foundation. This report summarizes the
data obtained during this study and presents our conclusions, design recommendations
and other geotechnical engineering considerations based on the proposed construction
and the subsoil conditions encountered.
PROPOSED CONSTRUCTION
The existing Tivoli Lodge will be razed prior to new construction. The proposed
lodge will roughly occupy the same footprint as the existing lodge and be a 4 story
structure with a loft apartment over one level of below grade parking. The parking level
floor will be slab-on-grade. Grading for the structure is assumed to be relatively minor
with cut depths between about 10 to 12 feet. The elevator pit will extend to about 4 feet
below the parking garage floor level. We assume moderate to relatively heavy
foundation loadings carried by both perimeter walls and interior columns.
If building loadings, location or grading plans change significantly from those
described above, we should be notified to re-evaluate the recommendations contained in
this report.
H-P GEOTECH
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SITE CONDITIOn*S
The site is currently occupied by a 3 story lodge over a garden level which opens
out to thc pool at the south side, see Fig. 1. Asphalt parking areas are adjacent to the
building on the north and west sides. A timber retaining wall is located at the rear of
the building to the south of the pool. Excavation depths for the existing building and
pool (that extends to below the lower building levcl) appears to be between about 5 to
12 feet. The ground surface surrounding the existing building is relatively flat with a
gentle slope down the north. Vegetation consists of lawn and pine trees.
FIELD EXPLORATION
The field exploration for the project was conducted on October 17,2002. Four
exploratory borings were drilled at the locations sholvn on Fig. 1 to evaluate the
subsurface conditions. The borings rvere advanced with 4-inch diameter continuous
flight augers powered bv a truck-mounted CME-45B drill rig. The borings were logged
by a representative of Hepworth-Pawlak Geotechnical, Inc.
Samples of the subsoils were taken rvith 17e inch and 2 inch I.D. spoon
samplers. The samplers rvere driven into the subsoils at various depths with blows from
a 140 pound hammer falling 30 inches. This test is similar to the standard penetration
test described by ASTM Method D-1586. The penetration resistance values are an
indication of the relative density or consistency of the subsoils. Depths at which the
samples were taken and the penetration resistance values are shorvn on the Logs of
Exploratory Borings, Fig.2. The samples were returned to our laboratory for review by
the project engineer and testing.
SUBSURFACE CONDITIONS
Graphic logs of the subsurface conditions encountered at the site are shown on
Fig. 2. The subsoils, below a shallow clayey fill and topsoil depth, consist of up to
about 2'/: feet of loose to medium dense silty sand overlying relatively dense, slightly
silty sand.v gravel containing cobbles and boulders to the maximum explored depth of
17 feet. Approximately 4 inches of asphalt overlies the fill at Boring 4 in the parking
H-P GEoTEcH
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lot. Drilling in the dense gravel with auger equipment was difficult due to the cobbles
and boulders and drilling refusal was encountered in the deposit at each boring location.
Laboratory testing performed on samples obtained from the borings included
natural moisture content and density, and gradation analyses. Results of gradation
analyses performed on small diameter drive samples (minus lV:. inch fraction) of the
natural coarse granular subsoils are shown on Fig. 4. The laboratory testing is
summarized in Table I.
No free water was encountered in the borings at the time of drilling or when
checked several days later and the subsoils were slightly moist to moist.
ENGINEERING ANALYSIS
Construction of the lodge as currently proposed should be feasible based on
geotechnical considerations. The excavation side slopes should be laid back to a stable
grade or shored in order to prevent construction-induced slope instability. Debris from
the existing building and site improvements should be completely removed from the
property. The borings with PVC casing should be monitored for water level through next
spring.
The natural coarse granular subsoils are relatively dense and should support spread
footings with moderate bearing capacity and relatively Iow settlement potential.
Settlements could be differential between footings with large variation in loadings which
should be evaluated during design. A seismic soil profile ofS"based on the 1997
Uniform Building Code can be used for bearing on the coarse granular subsoils.
DESIGN RECOMMENDATIONS
FOUNDATIONS\
Considering the subsoil conditions encountered in the exploratory borings and
the nature of the proposed construction, we recommend the building be founded with
spread footings bearing on the natural coarse granular subsoils.
The design and construction criteria presented below should be observed for a
spread footing foundation system.
H-P GEoTEcH
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l) Footings placed on the undisturbed natural granular soils should be
designed for an allowable soil bearing pressure of 6,000 psffor footings
at least 4 feet wide and 4,000 psffor narrower footings. A one-third
increase in the respective maximum bearing pressure can be taken for
eccentrically loaded footings provided the resultant of all forces acts
within the central third of the footing section. Based on experience, we
expect settlement of footings designed and constructed as discussed in
this section will be about 1 inch or less.
2) The footings should have a minimum width of 18 inches for continuous
walls and 2 feet for isolated pads.
3) Exterior footings and footings beneath unheated areas should be provided
with adequate soil cover above their bearing elevation for frost
protection. Placement of foundations at least 48 inches below exterior
grade is typically used in this area.
4) Continuous foundation walls should be reinforced top and bottom to span
local anomalies such as by assuming an unsupported length of at least
10 feet. Foundation walls acting as retaining structures should also be
designed to resist lateral earth pressures as discussed in the "Foundation
and Retaining Walls" section of this report.
5) All existing fill, topsoil, debris and any loose sand or disturbed soils
should be removed and the footing bearing level extended down to
relatively dense natural granular soils. Voids created by removal of
boulders can be backfilled with concrete or compacted sand and gravel.
If water seepage is encountered, the footing areas should be dewatered
before concrete placement.
6) A representative of the geotechnical engineer should observe all footing
excavations prior to concrete placement to evaluate bearing conditions.
FOUNDATION AND RETAINING WALLS
Foundation walls and retaining structures which are laterally supported and can
be expected to undergo only a slight amount of deflection should be designed for a
lateral earth Pressure computed on the basis of an equivalent fluid unit weight of 50 pcf
for backfill consisting of the on-site granular soils. Cantilevered retaining structures
H.P GEoTEcH
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which can be expected to deflect sufficiently to mobilize the full active earth pressure
condition should be designed for a lateral earth pressure computed on the basis of an
equivalent fluid unit weight of 40 pcf for backfill consisting of the on-site granular soils.
All foundation and retaining structures should be designed for appropriate
hydrostatic and surcharge pressures such as adjacent footings, traffic, construction
materials and equipment. The pressures recommended above assume drained
conditions behind the walls and a horizontal backfill surface. The buildup of water
behind a wall or an upward sloping backfill surface will increase the lateral pressure
imposed on a foundation wall or retaining structure. An underdrain should be provided
to prevent hydrostatic pressure buildup behind walls.
Backfill should be placed in uniform lifts and compacted to at least 90Vo of. the
maximum standard Proctor density at a moisture content near optimum. Backfill in
pavement and walkway areas should be compacted to at least 95Vo of the maximum
standard Proctor density. Care should be taken not to overcompact the backfill or use
large equipment near the wall, since this could cause excessive lateral pressure on the
wall. Some settlement of deep foundation wall backfill should be expected, even if the
material is placed correctly, and could result in distress to facilities constructed on the
backfill. Compacting the granular backfill to at least 98% of standard Proctor density
could be used to help reduce the settlement potential.
The lateral resistance of foundation or retaining wall footings will be a
combination of the sliding resistance of the footing on the foundation materials and
passive earth pressure against the side of the footing. Resistance to sliding at the
bottoms of the footings can be calculated based on a coefficient of friction of 0.5.
Passive pressure of compacted bacKill against the sides of the footings can be
calculated using an equivalent fluid unit weight of 400 pcf. The coefficient of friction
and passive pressure values recommended above assume ultimate soil strength.
Suitable factors of safety should be included in the design to limit the strain which will
occur at the ultimate strength, particularly in the case of passive resistance. Fill placed
against the sides of the footings to resist lateral loads should be a granular material
compacted to at least 95Vo of. the maximum standard Proctor density at a moisture
content near optimum.
H-P GEoTEcH
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FLOOR SLABS
The natural on-site dense granular soils, exclusive of topsoil, are suitable to
support lightly to moderately loaded slab-on-grade construction. To reduce the effects
of some differential movement, non-structural floor slabs should be separated from all
bearing walls and columns with expansion joints which allow unrestrained vertical
movement. Floor slab control joints should be used to reduce damage due to shrinkage
cracking. The requirements for joint spacing and slab reinforcement should be
established by the designer based on experience and the intended slab use. A minimum
4-inch layer of free-draining gravel should be placed beneath floor slabs to facilitate
drainage. This material should consist of minus 2-inch aggregate with atleast 50Vo
retained on the No.4 sieve and less than2Vo passing the No. 200 sieve.
All fill materials for support of floor slabs should be compacted to atleast 95Vo
of maximum standard Proctor density at a moisture content near optimum. Required fill
can consist of the on-site gravels devoid of vegetation, topsoil and oversized rock.
UNDERDRAIN SYSTEM
Although free water was not encountered during our exploration, it has been our
experience in the area that the groundwater level can rise and local perched groundwater
can develop during times of heavy precipitation or seasonal runoff. Frozen ground
during spring runoff can create a perched condition. We recommend below-grade
construction, such as the lower parking area, be protected from wetting and hydrostatic
pressure buildup by an underdrain system.
The drains should consist of drainpipe placed in the bottom of the wall backfill
surrounded above the invert level with free-draining granular material. The drain
should be placed at each level of excavation and at least 1 foot below lowest adjacent
finish grade and sloped at a minimum lVo to a suitable gravity outlet or sump and pump.
Free-draining granular material used in the underdrain system should contain less than
zVo passing the No. 200 sieve, less than 507o passing the No. 4 sieve and have a
maximum size of 2 inches. The drain gravel backfill should be at least lVzf.eet deep.
The perimeter foundation walls should be water proofed and covered with a drainage
mat or drain gravel layer that connects to the perimeter underdrain.
H.P GEoTEcH
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SURFACE DRAINAGE
I The following drainage precautions should be observed during construction and
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maintained at all times after the building has been completed:
I 1) Inundation of the foundation excavations and underslab areas should be
t uvoided during construction.
| 2) Exterior backfill should be adjusted to near optimum moisture and
t compacted to at least 95Vo of. the maximum standard Proctor density in
I pavement and slab areas and to at least 907o of the maximum standard
I Proctor density in landscape areas.
| 3) The ground surface surrounding the exterior of the building should be
I sloped to drain away from the foundation in all directions. We
I recommend a minimum slope of 12 inches in the first L0 feet in unpaved
I areas and a minimum slope of 3 inches in the first 10 feet in paved areas.
. Free-draining wall backfill should be capped with about 2 feet of finer-
I graded soils to reduce surface water infiltration.
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4) Roof downspouts and drains should discharge well beyond the limits of
I all backfill.
LIMITATIONS
This study has been conducted in accordance with generally accepted
geotechnical engineering principles and practices in this area at this time. We make no
warranty either expressed or implied. The conclusions and recommendations submitted
in this report are based upon the data obtained from the exploratory borings drilled at
the locations indicated on Fig. 1, the proposed type of construction and our experience
in the area. Our findings include interpolation and extrapolation of the subsurface
conditions identified at the exploratory borings and variations in the subsurface
conditions may not become evident until excavation is performed. If conditions
encountered during construction appear different from those described in this report, we
should be notified so that re-evaluation of the recommendations may be made.
This report has been prepared for the exclusive use by our client for design
purposes. We are not responsible for technical interpretations by others of our
information. As the project evolves, we should provide continued consultation and field
H-P GEOTECH
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services during construction to review and monitor the implementation of our
recommendations, and to verify that the recommendations have been appropriately
interpreted. Significant design changes may require additional analysis or modifications
to the recommendations presented herein. We recommend on-site observation of
excavations and foundation bearing strata and testing of structural fill by a
representative of the geotechnical engineer.
Sincerely,
HEPWORTH - PAWLAK GEOTECHNICAL. INC.
Trevor L. Knell
Reviewed by:
Steven L. Pawlak,
TLK/ksw
Monroe Fox
rsiF;ird
1.1i.[or9ie
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H.P GEOTECH
I ,orn*n
BENCH MARK: TOP OF $,AIER VAL\E;
ELEV. = 100.0', ASSUMED.
VAIL VALi-EY ROAO
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PROPOSED
BUILDING
L-1
BORING 4
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EXISTING
BUILDING
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HEPWORTH-PAWLAK
GEOTECHNICAL, INC.LOCANON OF EXPLORATORY BORINGS
BORING 1
ELEV.= 100.9'
BORING 2
ELEV.= 103.6'
BORING 3
ELEV.= 104.8'
BORING 4
ELEV.=' 100.3'
14/12
2an2
7/12
f,C-7.0
DD-112
-200.34
1s/6,6/1
APPROXIIATE
PROPOSTD
PAR(ING
TEVEL
3/12
31/12
rc=5.9
+4-zE .
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37/12
7/12
12/6,1E/3
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Note: Explonotion of Bynbols is shoryn on Fig. l.
102 672 HEPWORTH_PAWLAK
GEOTECHNICAL, INC.LOGS OF EXPLORATORY BORINGS Fig. 2
I LEGEND:t;
I lllll HOT BITUMININOUS ASPHALT; opproximotely 4 inches thick. Boring 4 onty.I ilil|I rJ.ur
I I ts7
I () FILL; slightly sondy to sondy cloy with scottored grovel, firm, moist, brown.I tr\l t-ta
I Fl TOPSOIL; sondy cloy, orgonic, firm, moist, dork brown.
ld
I I rtrl I V.t SAND (SM); silty, with grolrcl, loose to medium dense, slightly moist, brown.I IEJ
I Fttr.{
I F..4 GRA\€L AND COBBLES (GM-GP); sondy, slightly silty to silty, with boulders. dense, slighfly moist to
I W moist' brown'
I Ir
I t] Relotively undisturbed drive somple; 2-inch l.D. Colifornio liner somple.
ll lr I I Drive somple; stondord penetrotion test (SPT), 1 3/8 lnch l.D. split spoon somple, ASIU D-1566.
a a ra., Drivc somple blow count; indicotes thot 14 blows of o 140 pound hommer folling 30 inches were t+/ tz requlred to drive the Colifomio or SPT sompler 12 inches.
Procticol drilling refusol.
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NOTES:
1. Explorotory borings were drilled on October 17, 2OOZ with o 4-inch diometer continuous flight
Power ougcr.
2. Locotions of explorotory borings were mcosured opproximotely by pocing from feotures shown on the site
plon provided.
3. Elewtlons of cxplorotory borings were meosurcd by instrument level ond rcfer to the Bench Mork shown
on Flg. 1.
4. _Thc. explorotory boring locotions ond elevotions should be considered occurote only to the degree implied
by the method used.
5. thc lines between moteriols shown on the explorotory boring logs represent the opproximote boundories
between moteriol tlpes ond tronsitions moy be groduol.
6. No free woter wos encountered in the borings of the time of drilling or when checked 11 dop loter.
Fluctuotion in woter level moy occur with time.
7. Loborotory Testing Results:
fVC=WoterContent(Z)
DD - Dry Density ( pcf )14 = Percent retoined on No. 4 sieve.
-200 = Percent possing No. 200 sieve.
102 672 HEPWORTH_PAWLAK
GEOTECHNICAL, INC.LEGEND AND NOTES Fig. 3
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DIAMEIER OF PARTICLES IN MILLIMETERS
st.5 76.2 152
127
cltY to g.r
GRA\EL 48 %
UQUID LIMIT
SAND
%
GRA\EL 2E %
UQUID LIMIT
SAMPLE OF: Silty Grovelly Sond
o09c€s
Z SILT AND CLAY 15 Z
PLASTICITY INDEX %
FROM: Boring 2 ot 1O ond 15 feet combined
ctllR sau^nE egt|os
t/C | 1/t r
% SILT AND CLAY 25
PLASTICITY INOEX %
FROM: Boring 3 ot 5 feet
7-'
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SAMPLE OF: Silty Sondy Grovel
lLE tEADrqt U.s. STATiDAD SEFF
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.6 .O .Ote .O:;2 m1 .i& JO .adt t.tl ZU 1rC t5rZ5 tt.O
DIAME1ER OF PARTICLES IN MILUMEIERS
cuY ro gtt
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SAND 47
102 672 HEPWORTH-PAWLAK
GEOTECHNICAL. INC.GRADAT]ON TEST RESULTS Fig. 4
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