HomeMy WebLinkAboutSubsoil Studyffi CTLITHOMPSON
GEOTECHNICAL ENG]NEERING INVESTIGATION
49I HIGH ASPEN DRIVË, PHASE 2
GARFIELD COUNTY, COLORADO
Prepared For:
GREEN LINE ARCHITECTS
64 North 4th Street, Suite 5
Carbondale, CO 81623
Attention:
Steve Novy,
Project No. GS06 546.AA1-125
July 12,2022
CTllThompson. lnc.
Colorado Sprinos, Gle¡lggodj$pdngg, Pueþlo, $ummit County - Colorado
Cheyenne, lÁ/yoming and Bozeman, Montana
Denvêr, Fort Collins,
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TABLE OF CONTENTS
scoPE......
SUMMARY OF CONCLUS¡ONS
SITE CONDIÏIONS
PROPOSED CONSTRUCTION .
SITE GEOLOGYAND GEOLOGIC HAZARDS
SUBSURFACE CONDIT¡ONS..........
SITE EARTHWORK.....
Excavations
Subexcavation and Structural Fill..
Foundation Wall 8ackfi11................
BUtLDtNG FOUNDATIONS..................
Footings on Structural Fill .................
Drilled Piers .................
SLAB-ON-GRADE CONSTRUCTION ..
CRAWL SPACE CONSTRUCTION......
FOUNDATION WALLS...
suBsuRFACE DRA|NAGE..................
SURFACE DRAINAGE
CONCRETE
CONSTRUCTION OBSERVATIONS ...
GEOTECHN]CAL RISK
LtMlrATloNS ................
FIGURE 1-VIC¡NITYMAP
FIGURE 2 - AERIAL PHOTOGRAPH
FIGURE 3 - PROPOSED CONSTRUCT¡ON
FIGURES 4 AND 5 - SUMMARY LOGS OF EXPLORATORY BOR¡NGS
FIGURES 6 AND 7 - SWELL-CONSOLIDATION TEST RESULTS
FIGURE 8 - FOUNDAT¡ON WALL DRAIN CONCEPT
TABLE I - SUMMARY OF LABORATORY TESTING
GREEH LI¡¡E ÁRC¡{ITECTS
49I I{IGH ASPEN DRIVE, PHASE 2
CTLIT PROJECT NO. GS06546.00t-125
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SCOPE
CTllThompson, lnc. (CTLIT) has completed a geotechnicalengineering in-
vestigation for Phase 2 af construction at 491 High Aspen Drive within High Aspen
Ranch in Garfield County, Colorado. We conducted this investigation to evaluate
subsurface conditions at the site and provide geotechnical engineering recommen-
dations for the proposed construction. The scope of our investigation was set forth
in our Proposal No. GS 22-0'139. Our report was prepared from data developed
from our field exploration, laboratory testing, engineering analysis, and our experi-
ence with similar conditions. This report includes a description of the subsurface
conditions observed in our exploratory borings and provides geotechnical engi-
neering recommendations for design and construction of foundations, floor sys-
tems, below-grade walls, subsurface drainage, and details influenced by the sub-
soils. A summary of our conclusions is below.
SUMMARY OF CONCLUSIONS
Subsurface conditions encountered in our exploratory borings at the
site generally consisted of surficial layer of topsoil ar 2 to 3 feet thick-
ness of existing fill, underlain by natural sandy clay to the total ex-
plored depth of 30 feet. Free groundwater was measured at a depth
af 29 feet in TH-1 at the time of drilling.
2.The natural sandy clay atthis site has potential for significant expan-
sion when wetted under building loads. Without mitigation, expansion
of the clay soil is likely to result in differential heave and damage to
the buildings. We judge the buildings can be constructed on footing
foundations, provided the soils are subexcavated to a depth of at
least 4 feet below footings and replaced with densely-compacted,
structural f¡l¡. A drilled pier foundation is a positive alternative that
would further mitigate risk of building movement.
We recommend subexcavation of the soils below interior floor slabs
to a depth of at least 4leet and replacement with densely-com-
pacted, structural fillto mitigate potential slab heave. Subexcavatíon
and replacement with structural fill to at least 1.5 feet is recom-
mended below driveways, concrete flatwork, and playing courts.
GREEN LINE ARCHITECTS
49I HIGH ASPE¡I DRIVE, PHASE 2
cTLlf PROJEGT ¡tO. GS86546.001 -1 25
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A foundation wall drain should be constructed around the perimeter
of the crawl space below the residence to mitigate water that infil-
trates backfill soils adjacent to the residence. Site grading should be
designed and constructed to rapidly convey surface water away from
the buildings.
SITE CONDITIONS
The subject site is at 491 High Aspen Drive (a.k.a. Lot 31, High Aspen
Ranch) in Garfield County, Colorado. A vicinihT map with the location of the site is
included as Figure 1. The subject property is a 35.35-acre parcel that is northwest
of the intersection of High Aspen Drive and Stover Valley Road. Previously, CTLIT
performed a geotechnical engineering investigation for a new clubhouse and pool
in the northeast part of the property (Project No. GS06546.000-125; report dated
April 16, 2A21'). A pond is in the northwest part of the site. A barn, stable/resi-
dence, and gravel parking area are currently located at the site. îhese structures
are shown on the aerial photo attached as Figure 2. Ground surface at the site
generally slopes at less than 5 percent down to the east and northeast. A photo-
graph of the site at the time of our subsurface investigation is below.
Looking northeast across site with drill rig at ïH-1
GREEN LltlE ARCHITECTS
49I HIGH ASPEFI ÞRIVË, PHASE 2
GTLIT PROJECT HO. GS06546.0ûr-r25
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PROPOSED CONSTRUCTION
We reviewed schematic design plans for the project by Green Line Archi-
tects (dated May 31 ,2A221. Existing buildings at the site will be deconstructed.
New construction will include a two-story ranch manager's residence with an at-
tached garage, a single-story officelgarage building, a tennis court, and a pickle-
ball court. Paved access drives and parking areas are planned. A site plan with the
proposed construction is shown on Figure 3. The plans indicate the lower-level
floor of the residence will be structurally-supported with a crawl space below. Slab-
on-grade floors are anticipated in the garage/office building and within the garage
of the residence.
We expect excavation depths of less than 10 feet for the proposed con-
struetion, including the recommended -Íeel subexcavation below footings and
floor slabs. Foundation loads for the buildings are expected to be less than 3,000
pounds per linear foot of foundation wall with maximum interior column loads of
less than 50-kips. The tennis and pickleball courts are anticipated as post-ten-
sioned slabs. We should be provided with architectural plans, as they are further
developed, so we can provide geotechnicallgeo-structuralengineering input.
SITE GEOLOGY ANÐ GEOLOG¡C HAZARDS
As part of our geotechnical engineering investigation, we reviewed geologic
mapping by the Colorado Geological Survey (CGS) titled, "Geologic Map of the
Carbondale Quadrangle, Garfield County, Colorado", by Kirkham and Wídmann
(dated 2t08r. The mapping indicates that trachyandesite bedrock {Pliocene
Epoch) is at or near the ground surface at the site. We did not encounter bedrock
in our exploratory borings. The natural sandy clay soils we found in our borings are
likely part of the undivided deposits of alluvium and colluvium (Holocene and Late
Pleistocene Epochs) that are mapped to the north and west of the subject site.
GREEÍ{ LINE ARCI{ITECTS
49' HIGH ASPEN ORIVE, PIIASE Z
cr|-fT pRoJEcT NO. 6506546.601-128
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We also reviewed the CGS map "Collapsible Soils and Evaporite Karst Haz-
ard Map of the Roaring Fork Valley, Garfield, Pitkin and Eagle Counties", by Jona-
than L. White (dated zAWr. This map indicates unconsolidated deposits in the ar-
eas adjacent to the subject site. These deposits are described as including collu-
vium, sheetwash, and alluvium. The map descriptions indicate these types of soils
are geologically recent and typically loosely-packed, porous, and dry. These soil
deposits are often prone to collapse when wetted, especially under applied building
loads. Our laboratory testing on samples from our exploratory borings indicate the
soils at this site have potential for expansion and not collapse. We judge that ex-
pansion of the soils is the primary hazard for structures at the site.
SUBSURFACE CONDITIONS
Subsurface conditions were investigated by directing drilling of four explora-
tory borings (TH-1 through TH4) at the site. The borings were drilled on April 18,
2022 with a track-mounted drill rig and solid-stem auger at the approximate loca-
tions shown on Figures 2 and 3. Exploratory drilling operations were directed by
our engineer, who logged subsurface conditions encountered and obtained repre-
sentative samples of the soils. Graphic logs of the soils encountered in our explor-
atory borings are included as Figures 4 and 5.
Subsurface conditions encountered in our exploratory borings at the site
generally consisted of surficial layer of topsoil ar 2 to 3 feet thickness of existing
fill, underlain by natural sandy clay to the total explored depth of 30 feet. Free
groundwater was measured at a depth of 29 feet in TH-1 at the time of drilling.
PVC pipe was installed in TH-1 and TH-4 to facilitate subsequent checks of
groundwater.TH-Z and TH-3 were backfilled immediately after exploratory drilling
was completed.
Samples of the soils obtained from our exploratory borings were returned to
our laboratory for pertinent testing. Four samples of the sandy clay selected for
GRËEhI LI¡¡Ë ARCHITECTS
49I HIG}I ASPEN DRIVE, PHASE 2
crllT PROJEeT NO. GS06546.601-125
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one-d¡mensional, swell-consolidation testing exhibited 1.6 to 3.9 percent swell
when wetted under an applied pressure of 1,000 psf. Engineering index testing on
two samples showed high plasticity with liquid limits of 72 and 58 percent, plastic-
ity indices of 35 and 31 percent, and 96 and 92 percent silt and clay (passing the
No. 200 sieve). Two samples of soil tested had water-soluble sulfate contents of
0.09 percent. Swell-consolidation test results are shown on Figures 6 and 7 . La-
boratory testing is summarized on Table l.
SITE EARTHWORK
Excavations
We expect excavation depths of less than 10 feet for the proposed construc-
tion, including the recommended 4-feet subexcavation below footings and floor
slabs. Based on our subsurface investigation, excavations at the site can be made
with conventional excavating equipment. Sides of excavations need to be sloped or
braced to meet local, state and federal safety regulations. The sandy clay at the
site will likely classiñ7 as a Type B soil based on OSHA standards governing exca-
vations. From a "trench" safety standpoint, temporary slopes deeper than 5 feet
that are not retained should be no steeper than I to 1 (horizontalto vertical) in Type
B soils. Contractors are responsíble for maintaining safe excavations. Contractors
should identifu the soils encountered and ensure that O$HA standards are met.
We do not expeet that excavations for the proposed construction will pene-
trate a free groundwater table. Excavations should be sloped to a gravity dis-
charge or to a temporary sump where water from precipitation and seepage can
be removed by pumping.
GREEN LI¡¡EARCH'TECTS
49I FI¡GH ASPEN DRIVË, FT{ASE 2
cTLfT PROJECT NO. GS06546.0Aí125
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Subexcavation and Structural Fill
Our laboratory testing and engineering experience indicate the natural
sandy clay at the site has significant potentialfor expansion when wetted under
building loads. We judge that the buildings can be constructed on footing founda-
tions with slab-on-grade floors, provided soils below the buildings are subexca-
vated to a depth of at least 4 teet below footing and slab elevations. The subexca-
vated soils should be with densely-compacted, structuralfill. The subexcavation
process should extend laterally at least 2 feet beyond the perimeter of the building
footprints.
The excavated soils from the site can be reused as structuralfill, provided
they are free of rocks larger than 4 inches in diameter, organÍc matter, and debris.
Structural fill soils should be moisture-conditioned to within 2 percent of optimum
moisture content, placed in loose lifts of I inches thick or less, and compacted to
at least 98 percent of standard Proctor (ASTM D 69g) maximum dry density. Mois-
ture content and density of structuralfill should be checked by a representative of
our firm during placement. Observation of the compaction procedure is necessary.
Foundation Wall Backfill
Proper placement and compaction of foundation wafl backfill is important to
reduce infiltration of surface water and settlement from consolidation of backfill
soils. This is especially important for backfill areas that will support driveways, pa-
tios, and sidewalks, The natural sandy clay soil can be used as backfill, provided it
is free of rocks larger than 4-inches in diameter, organics, and debris.
Backfill should be placed in loose lifts of approximately 10 inches thick or
less, moisture-conditioned to within 2 percent of optimum moisture content and
compacted to at least 95 percent of maximum standard Proctor (ASTM D 698) dry
GREE}I LINE ARCH¡TECTS
4Sl H|GH ASPEiI DRTVE, P¡{ASE 2
cTrfT pRoJEcT !{o. Gs06546.001-12
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density. Moisture content and density of the backfill should be checked by a repre-
sentative of our firm during placement. Observation of the compaction procedure
is necessary.
BUILDING FOUNDATIONS
The natural sandy clay at this site has potential for significant expansion
when wetted under building loads. Without mitigation, expansion of the clay soil is
likely to result in differential heave and damage to the buildings. We judge the resi-
dence and office/garage building can be constructed on footing foundations, pro-
vided the soils are subexcavated to a depth of at least 4 feet below footings and
replaced with densely-compacted, structural fill. The subexcavation and structural
fill should be in accordance with the Subexcavation and Structural Fill section.
A drilled pier foundation is a positive alternative that would further mitigate
risk of building movement. Drilled piers in expansive soils are designed and con-
structed to resist uplift from heave by anchoring in the soils below the depth of po-
tentialwetting. Typically, drilled foundations experience less movement, as com-
pared to footing foundations.
Recommended design criteria for footings and drilled piers are below.
These criteria were developed from our analysis of field and laboratory data, as
well as rur experience.
Footinss on Structural Fill
Footings should be supported on a minimum 3-feet thickness of
densely-compacted, structuralfill. The structuralfill should be in ac-
cordance with recommendations in the Subexcavation and Structural
Fill section.
Footings on the structuralfill can be designed using a maximum net
allowable bearing pressure of 3,000 psf. The weight of backfill soil
above the footings can be neglected for bearing pressure calculation.
GREEN L¡NE ARCH'ÏECTS
49I HIGH ASPEN DRIVE, PHASE 2
CTLIT PROJECT NO. GS08546.001-125
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A friction factor of 0.35 can be used to calculate resistance to sliding
between concrete footings and the structuralfill soil.
Continuous wall footings should have a minimum width of at least 16
inches. Foundations for isolated columns should have minimum di-
mensions aÍ 24 inches by 24 inches. Larger sizes may be required,
depending upon foundation loads.
Grade beams and foundation walls should be well-reinforced. We rec-
ommend reinforcement sufficient to span an unsupported distance of
at least 12feet.
The soils under exterior footings should be protected from freezing.
We recommend the bottom of footings be constructed at a depth of at
least 36 inches below finished exterior grades. The Garfield County
building department should be consulted regarding frost protection re-
quirements.
Piers should be designed for a maximum allowable end bearing
pressure of 12,000 psf and an allowable skin friction value of 1,2A0
psf. Skin friction should be neglected for the portion of the upper 3
feet of pier below grade beams.
Piers should be designed for a minimum deadload pressure of 50û
psf based on pier cross-sectional area. lf this deadload cannot be
achieved through the weight of the structure, the pier length should
be increased beyond the minimum values specified in the next para-
graph. The clay soil should be assigned a skin friction value of 1,24A
psf for uplifr resistance.
Piers should have minimum lengths of 25 feet. The pier length
should not exceed about 30 times the pier diameter.
Piers should be reinforced to full length with at least three No.5
(16mm), Grade 6t Ø2A Mpa) reinforcing bars (or the equivalent) to
resist a potential uplift tension. Reinforcement should extend into
grade beams and foundation walls.
A 6-inch continuous void will be required beneath allgrade beams
and foundation walls, between piers, to allow for potential soil heave
and concentrate the deadload of the building on the piers.
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Drilled Piers
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GREE¡¡ LINE ARCH¡TECTS
491 HIGH ASPEN ÐRtVË, PHASE 2
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Piers should be carefully cleaned prior to placement of concrete. To
reduce potentialfor problems during pier installation, we recommend
that a "drill and pouf construction procedure be used, in which con-
crete is placed in the pier holes immediately after the holes are
drilled, cleaned and inspected by our representative. Concrete
should not be placed by free fall in pier holes containing more than 3
inches of water.
Concrete should have sutficient slump to fillthe pier holes and not
hang on the reinforcement. We recommend a slump in the range of 5
to 7 inches.
Formation of mushrooms or enlargements at the top of piers should
be avoided during pier drilling and subsequent construction opera-
tions.
lnstallation of drilled piers should be observed by a representative of
CTLIT to identiff the proper bearing strata.
S LAB-ON.GRADE CONSTRUCTION
Slab-on-grade floors are anticipated in the garage/office building and within
the garage of the residence. Driveways and concrete flatwork will likely be adjacent
to the buildings. The tennis and pickleball courts are anticipated as post-tensioned
slabs-on-grade. We recommend subexcavation of the soils below interior floor
slabs to a depth of at least 4 feet and replacement with densely-compacted, struc-
turalfillto mitigate potential slab heave. Subexcavation and replacement with struc-
tural fill to at least 1.5 feet is recommended below driveways, concrete flatwork,
and playing courts. The structural fill should be in accordance with the Subexcava-
tion and Structural Fill section.
Based on our analysis of field and laboratory data, as well as our engineer-
ing experience, we recommend the following precautions to enhance potential per-
formance of slab-on-grade construction at this site.
Slabs should be separated from footings and column pads with slip
joints that allow free vertical movement of the slabs.
GRÉEN LIHE ARCH¡TECTS
49f H|GH ASPEiI DRIVE, PHASE 2
cTllr PROJECT NO. GS06546.001.125
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2,The use of underslab plumbing should be minimized. 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 províded with flexible cou-
plings to slab supported appliances.
Exterior concrete flatwork should be isolated from the building. These
slabs should be well-reinforced to function as independent units.
Movements of these slabs should not be transmitted to the building.
Frequent controljoints should be provided, in accordance with Ameri-
can Concrete lnstitute (ACl) recommendations, to reduce problems
associated with shrinkage and curling.
CRAWL SPACE CONSTRUCT¡ON
The plans indicate the lower-level floor of the residence will be structurally-
supported with a crawlspace below. The minimum crawl space height depends on
the materials used to construct the floor system above the space. Building codes
normally require a clear space of at least 18 inches between exposed earth and un-
treated wood components of the structuralfloor. For non-organic systems, we rec-
ommend a minimum clear space oÍ 12 inches. This minimum clear space shoufd be
maintained between any point on the underside of the floor system, including
beams, plumbing pipes, and floor drain traps and the soils.
Utility connections, including water, gas, air duct, and exhaust stack connec-
tions to appliances on structural floors should be capable of absorbing some deflec-
tion of the floor. Plumblng that passes through the floor should ideally be hung from
the underside of the structural floor and not laid on the bottom of the excavation. lt
is prudent to maintain the minimum clear space below all plumbing lines.
Control of humidity in crawl spaces is ímportant for indoor air quality and per-
formance of wood floor systems. We believe the best current practices to control
humidity involve the use of a vapor retarder or vapor barrier (10 mil minimum)
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4Sf ¡{tG¡{ ASPEN DRIVE, PHASE 2
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placed on the soils. The vapor retarderlbarrier should be sealed at joints and at-
tached to concrete foundation elements. lt may be appropriate to install a ventila-
tion system that is controlled by humidistat.
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, such as in crawl spaces. Many factors affect the values of the de-
sign lateral earth pressure. These factors include, but are not limited to, the type,
compaction, slope, and drainage of the backfill, and the rigidity of the wall against
rotation and deflection.
ln general, 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), design for a lower "active" lateralearth pressure may be appropriate. Our
experience indicates below-grade walls in typical buildings deflect or rotate slightly
under normal design loads, and that this deflection results in satisfactory wall per-
formance. Thus, the earth pressures on the walls will likely be between the "active"
and "at-rest" conditions.
For backfill soils conforming with recommendatians in the Foundation Wall
Backfill section that are not saturated, we recommend design of below-grade walls
at this site using an equivalent fluid density of at least 45 pcÍ. This value assumes
deflection; some minor cracking of walls may occur. lf very little wall deflection is
desired, a higher design value for the at-rest condition using an equivalent fluid
pressure of 60 pcf is recommended. An equivalent fluid pressure of 300 pcf can be
used for the "passive" earth pressure case.
GREE¡I L¡¡¡E ÂRCHITECTS
49I HIGH ASPEN Í'R¡VE, PHASE 2
crllT PROJECT HO. GS06546.001-t25
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SUBSURFACE DRA¡NAGE
Water from precipitation, snowmelt, and irrigation frequently flows through
relatively permeable backfTll ptaced adjacent to a buitding and collects on the sur-
face of less permeable soils at the bottom of the foundation excavation. This pro-
cess can cause wet or moist conditions in below-grade areas, such as crawl
spaces, and result in water pressure developing outside foundation walls. lf a
structurally-supported floor system with a crawl space is utilized for the building,
we recommend construction of a foundation wail drain around the perimeter of the
crawl space.
The exterior foundation wall drain should consist of 4-inch diameter, slotted,
PVC pipe encased in free-draining gravel. A prefabricated drainage composite
should be placed adjacent to foundation walls. Care should be taken during back-
fill operations to prevent damage to drainage composites. The drain should dis-
charge via a positive gravity outlet or lead to a sump where water can be removed
by pumping. The gravity outlet should not be susceptible to clogging or freezing.
lnstallation of a clean-out along the drainpipe is recommended. The foundation
walldrain concept is shown on Figure 8.
SURFA,CE DRAINAGE
Surface drainage is critical to the performance of foundations, floor slabs,
and concrete flatwork. Site grading should be designed and constructed to rapidly
convey surface water away from the buildings. Proper surface drainage and irriga-
tion practices can help control the amount of surface water that penetrates to faun-
dation levels and contributes to heave of soils that support foundations, slabs, and
other structures. Positive drainage away from foundations and avoidance of irriga-
tion near foundations also help to avoid excessive wetting of backfillsoils, which
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491 HÍGH ASPEN DRIVE, PHASE 2
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can lead to increased backfill settlement and possibly to higher lateral earth pres-
sures, due to increased weight and reduced strength of the backfill. We recom-
mend the following precautions.
The ground surface surrounding the exterior of the buildings should
be sloped to rapidly convey surface water away from the buildings in
all directions. ìÂ/e recommend a constructed slope of at least 12
inches in the first 10 feet (10 percent) in landscaped areas around
the buildings.
Backfill around the foundation walls should be moisture-treated and
compacted pursuant to recommendations in the Foundation Wall
Backfill section.
We recommend that the buildings be provided with roof gutters and
downspouts. The downspouts should discharge well beyond the lim-
its 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 dis-
charge pipes.
lrrigation should be limited to the minimum amount sufficient to main-
tain vegetation; application of more water will increase likelihood of
slab and foundation movements. Plants placed close to foundation
walls should be limited to those with low moisture requirements. lrri-
gated grass should not be located within 5 feet of the foundation.
Sprinklers should not discharge within 5 feet of foundations. Plastic
sheeting should not be placed beneath landscaped areas adjacent to
foundation walls or grade beams. Geotextile fabric will inhibit weed
growth yet still allow natural evaporation to occur.
CONCRETE
Concrete in contact with soil can be subject to sulfate attack. We measured
a water-soluble sulfate concentration of 0.09 percent in two samples of the natural
sandy clay from the site (see Table l). For this level of sulfate concentratlon, ACI
332-A8, "Code Requirements for Residential Concrete", indicates there are no
special cement requirements for sulfate resistance in concrete that is in contact
with the subsoils.
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4gl H|GH ASPE¡| DRME, PHASË 2
CTLIT PROJECT ¡¡O. GS06546.001-125
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ln our experience, superficial damage may occur to the exposed surfaces of
highly-permeable concrete, even though sulfate levels are relatively low. To con-
trolthis risk and to resist freeze-thaw deterioration, the water-to-cementitious ma-
terials ratio should not exceed 0.50 for concrete in contact with soils that are likely
to stay moist due to surface drainage or high-water tables. Concrete should have a
tolal air content of 60/o +l- 1.ía/o.
CONSTRUCTION OBSERVATIONS
We recommend that CTLIT be retained to provide construction observation
and materials testing services for the project. This would allow us the opportunity
to verify whether soil conditions are consistent with those found during this investi-
gation. lf others perform these observations, they must accept responsibility to
judge whether the recommendations in thÍs report remain appropriate. lt is also
beneficialto projects, from economic and practical standpoints, when there is con-
tinuity between engineering consultation and the construction observation and ma-
terials testing phases.
GEOTECHNICAL RISK
The concept of risk is an important aspect of any geotechnical evaluation.
The primary reason for this is that the analytical methods used to develop ge-
otechnical recommendations do not comprise an exact science. We never have
complete knowledge of subsurface conditions. Our analysis must be tempered
with engineering judgment and experience. Therefore, the recommendations pre-
sented in any geotechnical evaluation should not be considered risk-free. We can-
not provide a guarantee that the interaction between the soils and the proposed
structure will lead to performance as desired or intended. Our recommendations
represent our judgment of those measures that are necessary to increase the
chances that the structures will perform satisfactorily. lt is criticalthat all recom-
mendations in this report are followed.
GREEN L¡NE ARCHITECTS
49I HIGH ASPE¡¡ DR¡VE, PHASE 2
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This report was prepared for the exclusive use of the client. The infor-
mation, conclusions, and recommendations presented herein are based upon con-
sideration of many factors including, but not limited to, the type of structures pro-
posed, the geologic setting, and the subsurface conditions encountered. The con-
clusíons and recommendations contained in the report are not valid for use by oth-
ers. Standards of practice continuously change in geotechnical engineering. The
recommendations provided in this report are appropriate for about three years. lf
the proposed buildings are not constructed within three years, we should be con-
tacted to determine if we should update this report.
LIMITATIONS
Our exploratory borings provide a reasonable characterization of subsur-
face condítions at the site. Variations in subsurface conditions not indicated by the
borings will occur. We should be provided with architectural plans, as they are fur-
ther developed, so we can provide geotechnicallgeo-structural engineering input.
This investigation was conducted in a manner consistent with that level of
care and skill ordinarily exercised by geotechnical engineers currently practicing
under similar conditions in the locality of this project. No warranty, express or im-
plied, is made. lf we can be of further service in discussing the contents of this re-
port, please call.
crLlrHoMPSoN, tNc.Reviewed by:
E-ï,ìì
Ë.t.7
Project Engineer
GREEN LINE ARCHITECTS
49r ¡lrcll ASPEN DR¡VE, PHASE 2
CTLIT PROJECT NO. GS06646.00f-125
D
(
Manager
t5
7/2
ffi
o 500 lfxlo NOTE:
SC¡["E l' - 1ü10'
GREEN UNEARCH¡TECI1g
¡r$t lgdH AgFEûl Þñfi/E, Fl{AgE 2
PRO.'ECT NO. GSO6546.OOï -1 2ı
SATELLTTE IMAGE FROM MAXAR
(CoPYRTGHT 2A21)
Vicinity
ñ,lap Fls. I
LEGEND:
TH_1 APPROXIMATE LOCATION OF@ EXPLORATORY BORING
NOTE:
ffi
0 50 r00
SC¡{LE: 1' - 1øA'
GREEN LINEAHCHITECTS
4Bf HTGHASPEN DR|VE, P!{A8E2
PROJËCT NO. GSO65,46.OA1 -1 25
SATELLITE IMAGE FROM MAXAR
(coPYRrcHT 2A22)
Aerial
Photograph Flg. 2
LEGEN D:
TH_1 APPROXIMATE LOCATION OFO EXPLORATORY BORING
NOTE:
ffi
o 50 1ü)
SOÂLE: f'- l0O'
GREEN UNEARCHÍTECTA
¡¡gl HffoHASËll DHI!|E, FflAgEa
PRATECT NO. GSO6546.OO1 -1 25
BASE DRAWING BY GREEN LINE
ARCHTTECTS (DATED MAY 31 , 2A22)
TennÍs ond
Pickleboll Courts
r
I
TH-4t,
posed
Coretoker's
Residence
Garoge/oflice
Proposed
Construction
{lr'
TH-2
TH_1
1
Flg. 3
t-
UJ
1¡Jfr
tzot-
l!J
UJ
ïH-1
EL.7679
7680
7675 33r12
7674 24t12
7665
7660 19t12
7655
7650 g
3712
7645
7644
GREEN LIÑËARCHÍTECTS
491 HIGH ASPEN DRIVE. PFIASE 2
PROJETT NO. GS06546.00t -125
ïH-2
E1.7676
TH-3
8L.7675
TH4
E,L.7672
13t't2
19t12
311'|.2
13t12
27t12
33t12
2
3U12
46t12
39112
1t12
7680
7675
7670
7665
7660
7655
7650
7645
764t
Summary Logs of
ExploratbryBoiings
Frc 4
ffi
F-lrJuIL
zot-
fi¡Jul
ffi
LEGEND:
E
n
þ
TOPSOIL, CI.AY, SANDY, ORGANICS, WET, DARK BROWN.
FILL, GRAVET PARKING SURFACE, CI.AY, MEDIUM STIFF. MOIST, BROWN, DARK BROWN,
GRAY, RUST.
CLAY, SANDY, STIFF TO VERY STTFF, MOIST TO WET, GRAY, BROWN, RUST. (CH)
DRIVE SAMPLE. THE SYMBOL 33112 INDICATES 33 BLOWS OF A I4GPOUND HAMMER
FALLING 30 INCHES WERE REQUIRED TO DRIVE A 2.s-INCH O.D. CALIFORNIA.BARREL
SAMPLER 12INCHES,
g GROUNDWATER LEVEL MEASURED AT TIME OF DRILLING.
NOTES:
EXPLORATORY BORINGS WERE DRILLED ON APRIL 18.2022 WITH A TRACKMOUNTED
DRILL RIG AND 4.INCH D¡AMETER. SOLID-STEM AUGER.
2. PVC P¡PE WAS INSTALLED lN ïH-1 AND TH-4 TO FACILITATE SUBSEQUENT CHECKS OF
GROUNDWATER. OTHER BORINGS WERE BACKFILLED ¡MMEDÙATELY AFTER
EXPLORATORY DR¡LLING OPERATIONS WERE COMPLETED.
3. ELEVATIONS OF ËXPLORATORY SORINGS WERE ESTIMATED FROM GROUNÞ SURFACE
ELEVAT¡ON CONTOURS ON FIGURE 3.
4, THESE LOGS ARË SUBJECT TO THE EXPI.ANATIONS, LIMITATIONS AND CONCLUSIONS IN
THIS REPORT.
SUNf,MARY LEGEND OF EXPLORATORY BORINGS
1
GREEN LIFIEARCHITE TS
4S1 HIGHASPEN DRI\/E' PI{ASE2
PROJECT NO. GSd6546.00f -f 25 F¡G. 5
ffi
2.0I
cl,z{-rô-xl¡ts2-2o
(t
U'lll -.rÉ.fLEoo4
3
2
0
-2
0.1
APPLIED PRESSURE. KSF
1.0 10
DRY UNITWEÍGHT=
MOISTURÊ CONTËNT=
105 PCFzta u
100
Somple of CLAY, SANDY (CH)
From
From
TH.l AT 9 FEET
zo-rız
ft+u¡szO-t6tt,t¡¡
ff.eEo(t
-7
0.1
APPLIED PRËSSURE - KSF
Somple of cLAy, sANDY (cH)
10
DRY UNITWEIGHT=
MOISTURE CONTENT=
100
95 PCF
ZAJ T,TH-2 AT 14 FEET
GREEN LINEARCHITËCTS
HIGH ASPEN RÂNCH, PHASE 2
PROJECT NO. GS06546.t0", -l 25
Swell-Consolidation
Test Results
I tt tl I t I I r I
. EXPANSION UNDER CONSTANT
PRËSSURE DUE TO WETTING
tt
5
\
\\
,ì t
¿
itiil t t ttttti
' EXPANSION UNDER CONSTANT
- PRESSURE DUE TO WEÏTING
I I I I t I f It t tililit t tililrI\
\
\
L \
{
\\\
Il
\
Þ
1.0
FIG.6
ffi
0
-2
zot, -3z
o.x
UTs4zo
ØatËUJ -J
É.o-Eo(t€
0.1
APPLIED PRESSURE - KSF
1.0 10
DRY UNITWEIGHT=
MOISTURE CONTENT=
100
105 PCF
Zt.ø "t"
Somple of CLAY, SANDY (CH)
From
From
ÏH-3 AT 19 FEET
o
-1
-2
zq
2.s
3Lxlrl
ñazoıU'
uJÉ-Ô
o-
=o(t
.6
0.f
APPL¡ET} PRESSURE. KSF
Somple of cLAY, sANDY (cH)
t0
DRYUNITWEIGHT=
MOISTURE CONTENT=
1t0
ß1 PCF
ZSS "/"TH.4 AT 9 FEET
GREEN LINEARCHITECTS
HIGHASPEN RÁNCH, PHASE 2
PROJECT NO. GS06546.001 -.l 25
Swell-Consolidation
Test Results
.u
¡rilr t l tttilt
- EXPANSION UNDER CONSTANT
PRESSURE DUE TO WËTTING
\\
\
\
\
\
\
\\\
\"
(,)
(
/
rrllt t t ltlilt
. EXPANSION UNÐER CONSTANT
PRESSURE DUE TO WETTING
I
\
\
\t
\
\
\\\
I
\
\
i \
I
1.0
FIG.7
tr
2-t
SLOPE
PER
OSFIA
COVER E}MRE WDTH OF
BACKFI\
BELOTY-GRAOE WAI.I.
SUP JOINÍ
PREFAERICATE}
DRA¡T.IAGE
mHPOSm
(H¡RAû}RA¡N Sft{¡O
oR EOUMALSÍÍ)
GRAI/EL WÍIT{ NON-TTOì/EN
GEOTEfllE FABRIC (UIRAFI
l¿[ON OR EquvÄrifl).
ATTACH PI.ASIIC SHEEIING
TO FOUNDAÏOT.I
MINIMUM
I'INIMUM
OR BEÍOIIDl:f SI'IOPE FROM
BgfTOM OF FOOIING(wl[cHRER F GREATER]
4-IHCH DIAilNER FERFORA1ED R¡E¡D ORruN PPE
THE P¡PE SHOUU' BE PI¡Ctr} IN A'¡RS{CH W¡¡H
A StroPE OF AT LEASr 118-${CH DROP PER
FOOT OF DRAIN.
ENCåSE F|PE t¡t 1/2'TO 1-t/2' SCREEIIEI'
GRAI/EL ÞOg{D ERAf'Et I.ATERA¡..LY ÏO FOüNC
AltD AT tEASr 1/2 Hne'*fir OF FOOT|H6. FtrL
E}{NRE TRENCH WÍTH GRAì'E-
t{$tE
ÏHE BOTTO}' OF THE Í'RAIII SHOU[D BE AÏ I,.EAST 2 NCHES BELO¡T BOTTOM OF
FOOIIÍ-IO AT THE H¡EHEST FOü{T ÅilD SLOPË DONYil¡TARD TO A POSM/E GRAVIIY(X,NE[ OR TO A SUMP WHME WATER CT¡I BE REMSVED ry PUMPIHG.
GREEN UNEÂRCHITECTS¡l8t H¡gH ASP$¡ EAlvÊ, PI{AÊE 2
PROJECT NO. GSO6546.OO1-1 25
Foundation
Wall Drain
Concept Flg.8
TABLE ISUMMARY OF LABORATORY TESTINGPROJECT NO. GS06546.001 -1 25ffiDESCRIPTIONCLAY, SANDY (CH)CLAY, SANDY (CH)CLAY, SANDY (CH)CLAY, SANDY (CH)CLAY, SANDY (CH)CLAY, SANDY (CH)CLAY, SANDY (CH)CLAY, SANDY (CH)PASSINGNO.200SIEVE(%)9692SOLUBLESULFATES(%\0.090.09-SWELL(o/o\1.63.62.83.9ATTERBERG LIMITSPLASTICITYINDEX(o/r\3531LIQUIDLIMIT(o/o\7258DRYDENSITY(PCF)1041059695109105101105MOISTURECONTENT(ø/o\21.221.627.828.119.921.623.922.1DEPTH(FEET)4I1o14I19I19EXPLORATORYBORINGTH.1TH.1TH.1TH.2TH.3TH.3TH-4TH-4* SWELL MEASURED UNDER 1-OOO PSF APPLIED PRESSURE.Page 1 of 1