HomeMy WebLinkAboutSubsoil StudyAMERICAN
CEOSERYICES
Geotechnical Evaluation Report
0 Balck Diamond Rd, Glenwood Springs, GO 81601
Date: June 27,2021; Project No: 0341-WS21
AMERICAN
CECSERVICES
GEOTECJ{NICAL & MÂTERIATS
ENVIRONMENI,\L
STRUCTUR,AL
CIVIL
ENGINEERINC AND SCIENCE
a88-2764Jn
June 27,2021
PROJECT NO: 0341-WS2l
CLIENTS: Ms. Jerilyn Gross
Reference: Soil Testing / Lot-specific Geotechnical Evaluation, 0 Black Diamond Road, Glenwood
Springs, CO
At your request, we have completed the geotechnical evaluation for the referenced project in
accordance with the American GeoServices, LLC (AGS) Proposal. Results of our evaluation and
design recommendations are summarized below.
PROJECT INFORMATION
The site is located as shown in Figure 1 and Figure 2. The proposed development will consist of
residential construction. We do not anticipate significant site grading forthis project. We anticipate
proposed structure will be constructed with light to moderate foundation loads.
SCOPE OF WORK
Our scope of services included the geologic literature review, soil explorations, initial geologic
hazards evaluation, geotechnical evaluation, and the preparation of this report. Evaluation of any
kind of existing structures on and adjacent to the site was beyond our scope of services.
ln June 2021, we performed soil explorations (81 and 82) at approximate locations shown in
Figure 2 and collected soil/rock samples. Our soil exploration included logging of soils from soil
boring. Our explorations extended to a maximum depth of 6.25 feet below existing ground surface
(BGS). All soil/rock samples were identified in the field and were placed in sealed containers and
transported to the laboratory for further testing and classification. Logs of all soil explorations
showing details of subsurface soil conditions encountered at the site are included in an appendix.
The Legend and Notes necessary to interpret our Exploration Logs are also included in an
1338 Grand Avenue #306
Glenwood Springs, CO 81601
Ph: (303) 325 3869
www,americangeoservices,com
sma@american geoservices.com
Ph: (888) 276 4027
Fx: (877) 47I 0369
Maifing: 191 University Blvd, #375
Denver, CO 80206
Ph: (303) 32s 3869
appendix. Data obtained from site observations, subsurface exploration, laboratory evaluation,
and previous experience in the area was used to perform engineering analyses. Results of
engineering analyses were then used to reach conclusions and recommendations presented in
this report.
SURFACE CONDITIONS
The site is roughly an irregular-shaped parcel of land as shown in Figure 2. Currently the site
topography is moderately to steeply sloping. At the time of our site visit, there was no visual
indication of active slope instability or active landslides in the site vicinity. However, our review
of available geology maps and geologic hazards information did reveal the presence of possibly
active geologic hazards at or in the immediately vicinity of the site. lt should be noted that a
detailed geologic hazards evaluation was beyond our scope of services.
SUBSURFACE GONDITIONS
Subsurface conditions encountered in our explorations and noted in our literature research are
described in detail in the Exploration Logs provided in an Appendix and in the following
paragraphs. Soil classification and identification is based on commonly accepted methods
employed in the practice of geotechnicalengineering. ln some cases, the stratigraphic boundaries
shown on Exploration Logs represent transitions between soil types ratherthan distinct lithological
boundaries. lt should be recognized that subsurface conditions often vary both with depth and
laterally between individual exploration locations. The following is a summary of the subsurface
conditions encountered at the site.
Surface Conditions: Approximately 8-10 inches of topsoil, loam, sand, silt, clay and root mass
is present at the surface.
Sand-Silt-Clay Alluvium/Colluvium: Site is primarily underlain by medium stiff to very stiff
mixtures of sand-silt-clay (CL) extending to a depth of about 6.25 feet. These soils exhibited low
to medium plasticity in the field and in the laboratory. These soils may represent old debris flow
deposit or an ancient (inactive) landslide deposit. Below a depth of about 5 feet, CL soils appeared
as completely weathered shale bedrock or residuum.
Groundwater: Groundwater wãs not encounteréd during exploration ôr at the tlme of complétlon
of our soil explorations. This observation may not be indicative of other times or at locations other
than the site. Some variations in the groundwater level may be experienced in the future. The
magnitude of the variation will largely depend upon the duration and intensity of precipitation,
temperature and the surface and subsurface drainage characteristics of the surrounding area.
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PRELIMINARY GEOLOGIC HAZARDS EVALUATION
Expansive/Collapsible Soils: The site is possibly underlain by low to moderately expansive
clayey soils or clayey sedimentary bedrock materials. The site location is located within or near
known swell hazard soil zones that pose a significant geotechnical concern. Moreover, local
pockets of 'collapsible' soils/materials can occur through the site and may cause settlement in the
foundations or flatwork around the site.
Flooding: Proposed construction area is not located within 10O-yearflood hazard zone, however,
a flood hazard evaluation was beyond our scope of services. We recommend hiring an
experienced hydrologist to evaluate the flood hazards for the site, or an in-depth evaluation of
published flood hazard maps, considering the proximity of the site to the river.
Ðebris Flow: Site may be located within alluvial fans or flood channels. Debris flow hazard at the
site is minimal under normal site, topographic, geologic, and weather conditions. However, the
site vicinity area may consist of ancient debris flow or ancient landslide deposit, which is cunently
inactive. lf the owner is notwilling to assume any and all risks associated with debris flow hazards,
then we recommend performing a detailed debris flow hazard evaluation.
Rockfall: At the time of our site visit, rockfall hazards were not noted in the proposed construction
area. ln our opinion, rockfall hazard at the site are minimal under normal site, topographic,
geologic, and weather conditions. However, site vicinity area is located within or in the vicinity of
the general rockfall hazard zone as noted in Figure 6. Therefore, if the owner is not willing to
assume any and all risks associated with rocKall hazards, then we recommend performing a
detailed rockfall hazard evaluation.
Landslides: Our review of available geologic maps and landslide hazard maps did not indicate
that recent landslides or recent debris flow had occurred at the site or in the immediate proposed
building area. During our site reconnaissance, we did not notice scarps, crevices, depressions,
tension cracks in the ground surface, irregular slope toes, exposed surfaces of ruptures without
vegetation, presence of distinct fast-growing vegetation, undrained depressions, etc., that are
generally indicative of local active and/or inactive landslides or slope instability that would
adversely impact the on-site structure at this time, however, a detailed landslide evaluation of any
kind or detailed slope stability evaluation was beyond our scope of services.
Notwithstanding, the site vicinity area is located within the mapped landslide hazard areas
surrounding the site (Figure 6). There are potentially mapped landslides and/or ancient landslide
deposits close to the site boundaries. There is also moderate to high potential for the presence
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of dormant and/or unknown historic landslides, deep-seated ancient landslides, or geologically-
recently developed dormant landslides in the site vicinity close to the site.
The proposed construction area itself is not mapped as being situated within the existing active
or ancient active landslide mass or an ancient active global landslide. However, the site vicinity
area is mapped as having landslide hazards (Figure 6). Considering these findings, the site
topography, and site geologic conditions, it is our opinion that the immediate site vicinity area
have'site-specific landslide hazards'and has some'inherent'risk associated with slope instability
ãnd structural impact from the movement of any global/ancient landslide and loeäl slope
movements. Moreover, historically, with construction in such areas, there is always an inherent
risk associated with ground movement and/or settlements and related structural damage. The
owner should understand these inherent risks related to site vicinity. lf the owner wants to better
understand the risks and to eliminate the site-specific landslide hazard risks, then a detailed and
comprehensive geotechnical evaluation including deep drilling, detailed slope stability modeling,
and a detailed geologic hazards assessment (including global landslide hazards evaluation)
should be performed in the site vicinity area to quantify the abovementioned risks and to provide
detailed geotechnical design recommendations for comprehensive mitigation measures. Unless
these recommended studies are performed, the owner is completely responsible for taking all
risks associated with any future potential for instability at the site occurring due to landslide
hazards in the site vicinity.
lnitial Slope Stability Evaluation: Based on the results of our initial analyses (as discussed in
following paragraphs), in our opinion, at present there are no active slope instability hazards at
the site provided site drainage is properly maintained during the design life of the structure.
Using the results of geologic and soils literature review (as attached in the appendix) and site
reconnaissance data, we analyzed on-site slopes by performing preliminary slope stability
analysis. We used the software SLOPEM to model on-site slopes, subsurface soil conditions,
and the impact of existing construction on the stability of the site. We used several methods
(Bishop, Janbu, Spencei', etc.) in order to obtain the lowest factor of safety agälnst slope failures.
The SLOPEM computer software calculates the most likely failure plane based on topography,
subsurface conditions (including soil parameters), and groundwater conditions. The stability of
this most likely failure plane is calculated as the factor of safety (FOS), which is a ratio of the
resisting forces or shear strength to the driving forces or shear stress required for equilibrium of
the slope. A FOS of 1.0 indicates the resistive forces and driving forces are equal. A FOS below
1.0 indicates the driving forces are greater and the landslide is active. A FOS above 1.0 indicates
the resisting forces are greater and the slope is stable. Based on the engineering community and
our experience, a factor of safety in the range of 1.3-2.0 is generally acceptable to assure slope
stability in residential applications.
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lnitial slope stability analysis was performed using various input soil parameters derived from the
results of our subsurface exploration and laboratory evaluation, in order to properly evaluate the
stability of a slope. Of particular importance were surface and subsurface profiles (slope
geometry), soil strength parameters, and groundwater conditions. Based on our experience with
past slope stability evaluations in similar geologic conditions, soil strength parameters can vary
considerably. Notwithstanding, we used soil strength values typical of on-site soils and native
soils/bedrock based on our experience with soil strength testing, as well as back-calculation of
soil strength parameters for failed slopes in similar geologic conditions.
lnherent Slope lnstability Risks: Historically, with construction in areas adjacent to streams and
slopes, there is an inherent risk associated with slope failures along the stream banks. Although
there was no active slope instability observed within the proposed building envelope, and the
potential for future active slope failure is low, the owner is still responsible for taking any risks
associated with any existing or future potential for instability at the site or in the river bank areas.
Since this report and recommendations continued herein have been prepared in orderto maintain
a low degree of risk for future slope instability, all of our recommendations should be strictly
followed.
Earthquakes: Based on site geology, topography, and our preliminary evaluation, in our opinion,
the site is generally not considered to be located within highly active seismic area. Therefore,
anticipated ground motions in the region due to seismic activity are relatively low and do not pose
a significant hazard. Ground accelerations in excess of 0.19 to -0.29 are not anticipated to occur
at the site.
Based on the results of our subsurface explorations and review of available literature (2009
lnternational Building Code), in our opinion, a site classification "C" may be used for this project'
However, this site classification may be revised by performing a site-specific shear wave velocity
study.
Subsurface soil conditions at the site are not susceptible to liquefaction. Seismically induced slope
instability may occur on a global scale impacting not just the site but also the surrounding area,
however, such an evaluation was beyond our scope of services. A detailed seismic hazards
evaluation of the site was beyond our scope of services.
CONCLUSIONS AND RECOMMENDATIONS
Based on the results of our geotechnical evaluation, in our opinion, the site is suitable for the
proposed construction provided following recommendations are strictlyfollowed, and provided the
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owner is willing to assume any and all risks associated with geologic hazards described earlier in
this report. lt should be noted that our conclusions and recommendations are intended as design
guidance. They are based on our interpretation of the geotechnical data obtained during our
evaluation and following assumptions:
Proposed/Final site grades will not differ significantly from the current site grades;
Proposed foundations will be constructed on level ground; and
Structural loads will be static in nature.
Construction recommendations are provided to highlight aspects of construction that could affect
the design of the project. Entities requiring information on various aspects of construction must
make their own interpretation of the subsurface conditions to determine construction methods,
cost, equipment, and work schedule.
SHALLOW FOUNDATIONS
We recommend that the proposed structure be supported on shallow spread footings designed
and constructed in accordance with following criteria:
o Due to the presence of potential expansive soils, over-excavate the expansive soils from
within the foundation areas to a depth of 24 inches below the bottom of footings, then surficial
compact the excavated surface and callAGS for an open hole inspection.
Backfill with granular free-draining structural fill (or onsite sandy soils) compacted to at least
95% of ASTM D698 maximum dry density in order to achieve a "uniform subgrade" and to
facilitate the placement of foundation drain. Over-excavation can also be minimized or
eliminated based on the results of open-hole inspection or foundation subgrade inspection
performed by AGS. Onsite materials may be used as structural fill, provided they are
approved by AGS.
Foundations bearing upon properly prepared and approved subgrade should be designed for
a maximum allowable bearing pressure of 2,000 pounds per square foot (psf).
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Estimated final structural loads will dictate the final form and size of foundations to be
constructed. However, as a minimum, we recommend bearing walls be supported by
continuous footings of at least 18 inches in width, lsolated columns should be supported on
pads with minimum dimensions of 24 inches square.
Exterior footings and footings in unheated areas should extend below design/preferred frost
depth of 42 inches.
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Continuous foundation walls should be reinforced in the top and bottom to span an
unsupported length of at least 8 feet to further aid in resisting differential movement. As a
minimum, additional reinforcement as shown in Figure 11 should be placed.
. Foundation/stem walls should be adequately designed as retaining walls and adequate
drainage measures should be implemented as shown in Figure 12.
We estimate total settlement for foundations designed and constructed as discussed in this
section will be one inch or less, with differential settlements on the order of one-half to three-
fourths of the total settlement.
OPTIONAL: DRILLED PIERS or DEEP FOUNDATIONS
This option can be used if the owner wants to significantly reduce the risk of future differential
settlements/heave and related structural damage to a level of minimal to none, and to significantly
increase the safety factors for foundation stability. Following recommendations are provided to
highlight aspects of design and construction that could significantly affect the performance of the
project. Entities requiring information on various aspects of design must make their own
interpretation of the subsurface conditions. After the review of structural and architectural project
plans and proposed loads and grading, we may recommend deeper soil borings to confirm or to
modify following recommendations;
o Piers should have a minimum design length of 20 feet below the bottom of foundation level.
o The minimum pier diameter (D) will depend on the length (L) to diameter ratio (LlD). We
recommend the L/D not exceed 30"
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A minimum pier diameter of 12 inches is recommended to facilitate proper cleaning and
observation of the pier hole during construction. This recommendation can be modified after
the discussions with your foundation contractor and/or structural engineer.
Piers should be designed for an allowable end bearing capacity of 20,000 psf and an allowable
skin friction value of 1,500 psf for the minimum 10 feet embedded portion of the pier into the
very stiff to hard material present below a depth of 6 feet. Where there will be tension loads
or uplift on the piers, the tension loads should be resisted by skin friction of the pier embedded
below 10 feet of existing ground surface. The skin friction value of 1,250 psf can be used to
calculate uplift capacity.
Some movement of drilled pier foundations should be anticipated to mobilize skin friction. We
estimate the required movement will be on the order of I 18 to 114 inch. Differential movement
between adjacent piers may equalthe total movement.
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All axially loaded piers should have a minimum center-to-center spacing of at least three pier
diameters (3D). All laterally loaded piers should have a minimum center-to-center spacing of
at least six pier diameters (6D) in the direction parallel to pier loading, and 2.5 diameters
(2.5D) in the direction perpendicular to pier loading. Piers placed closer than these values
should be designed using the appropriate reduction factors to account for group action. For
the final design, the exact geometry of the pier group should be submitted to us for review and
approval so that appropriate modifications can be made to our recommendations.
Piers should be adequately reinforced to their full length. Reinforcement should extend well
into grade beams and walls. Steel to pier ratio of a minimum of 0.005 based on cross-sectional
area of pier is recommended. More reinforcement may be required from structural
considerations. As a minimum, one #5 rebar per 18-inch pier diameter should be used to resist
uplift tension generated by swelling soils.
The project specifications should allow for modifications by geotechnical engineer during the
pier installation.
The contractor should mobilize proper equipment so that drilling in gravels/river rock or
unanticipated hard materials can be achieved to required depths. The contractor should
carefully review this report to account for all possibilities and extras in their bid to avoid high
cost overruns.
The use of casing and dewatering equipment is not anticipated. However, it is contractor's
responsibility to make the determination regarding the use of casing and dewatering
equipment.
Mushrooming of the pier top should be avoided by not allowing the pier size to vary towards
the ground surface.
Drilled pier holes should be cleaned of loose material prior to concrete placement. Once the
proper depth is achieved, the auger should be placed in the bottom of the hole and several
high-speed revolutions should be made to clean the bottom. Loose cuttings should not remain
in the bottom of the excavations prior to concrete placement.
Concrete should be onsite and ready during drilling of piers. Concrete should be placed
immediately after pier observations and measurements are made, and reinforcement is set
within the hole. Groundwater was encountered during our investigation and is anticipated to
be a significant factor during construction of the piers. Pier holes should not be left "open"
overnight.
Concrete to be placed in the piers should have a slump of 4 to 7 inches. lf more than 3 inches
of water is present in the bottom of the pier hole, de-watering should be performed using a
pump or tremie prior to concrete placement.
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lnstallation of drilled piers should be observed by a member of American GeoServices, LLC
on a full-time basis to identifo and confirm that subsurface conditions are consistent with those
encountered in our soil borings, and to monitOr construction procedures.
Assuming that the pier length to diameter ratio (L/D) will be greater than 7, in our opinion, the
Matlock and Reese method of analysis can be used for lateral load analyses. Therefore, the
lateral soil-structure interaction of single shafts may be analyzed using the software
application, LPILE developed by Ensoft, lnc (or equivalent such as COM624). This analysis
procedure estimates the lateral load-displacement behavior based on elastic beam-column
theory and soil reaction-displacement (p-y) curves. Deflection, bending moment and shear
profiles at specified intervals along the length of the shaft are computed.
For lateral load analysis, modulus of horizontal subgrade reaction values of 20 tcf and 35 tcf
may be used for the overburden soils present in upper 10 feet and denser materials present
below 10 feet, respectively. Resistance to lateral load in upper 5 feet should be neglected.
As noted earlier, all laterally loaded piers should have a minimum center-to-center spacing of
at least six pier diameters (6D) in the direction parallel to pier loading, and 2.5 diameters
(2.5D) in the direction perpendicular to pier loading. Piers placed closer than these values
should be designed using the appropriate reduction factors to account for group action. For
the final design, the exact geometry of the pier group should be submitted to us for review and
approval so that appropriate modifications can be made to our recommendations. Total lateral
load versus deflection graph for the pier group can be developed by adding the lateral load
resistance of piers at selected deflections.
For a detailed LPILE analysis, we should be contacted to provide specific input soil
parameters or to review input parameters and to participate in the pile design along with
project structural engineers.
STRUCTURAL FLOOR & CRAWL SPACE
We understand a structural/framed floorwith crawl space may be used for this project. The grade
beams (if used) and floor system should be physically isolated from the underlying soil materials
with crawl-space type construction. The void or crawl space of minimum of 6 inches or whatever
mínimum curent Uniform Building Code (UBC) requirement is.
For crawl-space construction, various items should be considered in the design and construction
that are beyond the scope of geotechnical scope of work for this project and require specialized
expertise. Some of these include design considerations associated with clearance, ventilation,
insulation, standard construction praetice, and local building codes. lf not properly drained and
constructed, there is the potentialfor moisture to develop in crawl-spaces through transpiration of
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the moisture/groundwater within native soils underlying the structure, water intrusion from
snowmelt and precipitation, and surface runoff or infiltration of water through irrigation of lawns
and landscaping. ln crawl space, excessive moisture or sustained elevated humidity can increase
the potential for mold to develop on organic building materials. A quallfied professionäl engineer
in building systems should address moisture and humidity issues.
CRAWL SPACE PERIMETER/UNDERDRAIN SYSTEM
ln order for the crawl space to remain free of moisture, it is important that drainage
reeommêndations are properly implemented, and ädequate inspections are pêrformed priorto the
placement of concrete
As a minimum, subgrade beneath a structural floor system should be graded so that water
does not pond. Perimeter drains and under'slab drains should be installed in conjunction with
a sump pump system to eliminate the potential for ponding and any subsequent damage to
foundation and slab elements. The lot-specific perimeterdewatering, and underdrain systems
should be properly designed and connected to the area underdrain system or a sump-pump
system for suitable discharge from the lot.
Drainage recommendations illustrated in Figure 12 should be implemented. The subsurface
drainage system should consist typically of 4-inch minimum diameter perforated rigid PVC or
flexible pipe (rigid preferred due to depth of placement) surrounded by at least one pipe
diameter of free draining gravel. The pipe should be wrapped in a geosynthetic to prevent fine
soils from clogging the system in the future. The pipe should drain by gravity to a suitable all-
weather outlet or a sump-pit. Surface cleanouts of the perimeter drain should be installed at
minimum serviceability distances around the structure. A properly constructed drain system
can result in a reduction of moisture infiltration of the subsurface soils. Drains which are
improperly installed can introduce settlement or heave of the subsurface soils and could result
in improper surface grading only compounding the potential issues.
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The underdrain system should consist of adequate lateral drains and a main drain, regular
clean out and inspection locations, and proper connections to the sump-pump system for
discharge into suitable receptacles located away from the site.
The entire design and construction team should evaluate, within their respective field of
expertise, the curent and potential sources of water throughout the life of the structure and
provide any design/construction criteria to alleviate the potential for moisture changes. lf
recommended drain systems are used, the actual design/layout, outlets, locations, and
construction means, and methods should be observed by a representative of AGS.
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SLAB.ON.GRADE AND PERIMETER/U NDERDRAIN SYSTEM
Groundwater is not expected to be at depths below the proposed foundation levels if excavation
is performed during dry seasons. ln order to assure proper slab-on-grade construction (if used),
following recommendations should be strictly followed:
A perimeter dewatering system should be installed to reduce the potential for groundwater
entering slab-on-grade areas. The lot-specific perimeter dewatering should be properly
designed and connected to the area underdrain system or a sump-pump system for suitable
discharge from the lot.
As a minimum, drainage recommendations illustrated in Figure 12 should be implemented.
The subsurface drainage system should consist typically of 4-inch minimum diameter
perforated rigid PVC or flexible pipe (rigid preferred due to depth of placement) surrounded
by at least one pipe diameter of free draining gravel. The pipe should be wrapped in a
geosynthetic to prevent fine soils from clogging the system in the future. The pipe should
drain by gravity to a suitable all-weather outlet or a sump-pit. Surface cleanouts of the
perimeter drain should be installed at minimum serviceability distances around the structure.
A properly constructed drain system can result in a reduction of moisture infiltration of the
subsurfâce soils. Dra¡ns whieh are improperly installed can introduce sêttlêmênt or hêavê of
the subsurface soils and could result in improper surface grading only compounding the
potential issues.
o The entire design and construction team should evaluate, within their respective field of
expertise, the current and potential sources of water throughout the life of the structure and
provide any design/construction criteria to alleviate the potential for moisture changes. lf
recommended drain systems are used, the actual design/layout, outlets, locations, and
construction means, and methods should be observed by a representative of AGS.
The "Slab Performance Risk" associated with native soils is "Low to moderate". Therefore, the
slab can be constructed as a slab-on-grade provided the owner is aware that there is still potential
risk of some slab movement due to presence of possibly expansive soils. ln order to reduce this
potential, recommendations given for the over-excavation and backfilling of the foundation areas
should be used for the slab areas as well.
The actual slab movements that will occur on a particular project site are very difficult, if not
impossible, to predict accurately because these movements depend on loads, evapo-
transpiration cycles, surface and subsurface drainage, consolidation characteristics, swell index,
swell pressures and soil suction values. The actual time of year during which the slab-on-grade
is constructed has been found to have a large influence on future slab-on'grade movements.
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RETAINING WALL
Retaining walls for at-rest conditions can be designed to resist an equivalent fluid density of 55
pcf for on-site fili materials if needed only imported granular backfill meeting CDOT Class 1
structural backfill should be used. Retaining walls for unrestrained conditions (free lateral
movement) can be designed to resist an equivalent fluid density of 35 pcf for on-site fill materials
and 35 pcf for imported granular backfill or CDOT Class 1 structural backfill. For passlve
resistance of unrestrained walls, we recommend passive resistance of 300 psf per foot of wall
height. A coefficient of friction value of 0.35 may be used for contact between the prepared soil
surface and concrete base.
The above recommended values do not include a factor of safety or allowances for surcharge
loads such as adjacent foundations, sloping backfill, vehicle traffic, or hydrostatic pressure. We
should be contacted to provide additional recommendations for any specific site retaining
conditions.
Retaining wall backfill should be placed in strict accordance with our earthwork recommendations
given below and as illustrated in Figure 12. Backfill should not be over-compacted in order to
minimize excessive lateral pressures on the walls. As a precautionary measure, a drainage
collection system (drains or geosynthetic drains) should be included in the wall design in order to
minimize hydrostatic pressures. A prefabricated drainage composite or drain board such as the
MiraDrain 2000 or an engineer-approved equivalent may be installed along the backfilled side of
the basement foundation wall.
EARTHWORK CONSTRUCTION
Site grading should be carefully planned so that positive drainage away from all structures is
achieved. Following earthwork recommendations should be followed for all aspects of the project.
Fill material should be placed in uniform horizontal layers (lifts) not exceeding I inches before
compacting to the required density and before successive layers are placed. lf the contractor's
equipment is not capable of properly moisture conditioning and compacting f-inch lifts, then the
lift thickness shall be reduced until satisfactory results are achieved.
Clays or weathered sandstonê/Õlaystonê bedrock (lf encountered) should not be re-used onsite
except in landscaped areas. lmport soils should be approved by AGS prior to placement. Fill
placement obseruations and fill compacüon fesfs should be performed by AGS Engineering in
order to minimize the potential for future problems. Fill material should not be placed on frozen
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ground. Vegetation, roots, topsoil, the existing fill materials, and other deleterious material to
depth of approximately 6 inches should be removed before new fill material is placed.
On-site fill to be placed should be moisture treated to within 2 percent of optimum moisture content
(OMC) for sand fill and from OMC to 34 percent above OMC for clay and weathered bedrock.
Fill to be placed in wall backfill areas and driveway areas and all other structural areas should be
compacted to 95o/o of Standard Proctor (ASTM D 698) dry density or greater. Compaction in
landscape areas should be 85% or greater.
lmported structural fill should consist of sand or gravel material with a maximum particle size of 3
inches or less. ln addition, this materialshall have a liquid limit less than 30 and a plasticity index
of 15 or less. Structural fill should also have a percent fine between 15 to 30 percent passing the
No. 200 sieve. Structural fill should be moisture conditioned to within 2 percent of OMC and
compacted to at least 95 percent of Standard Proctor (ASTM D698) dry density.
ln our opinion, the materials encountered at this site may be excavated with conventional
mechanical excavating equipment. For deeper excavations, heavier equipment with toothed
bucket may be required. Although our soil explorations did not reveal "buried" foundation elements
or other structures or debris within the building footprint, these materials may be encountered
during excavation activities. Debris materials such as brick, wood, concrete, and abandoned
utility lines, if encountered, should be removed from structural areas when encountered in
excavations and either wasted from the site or placed in landscaped areas.
Temporary excavations should comply with OSHA and other applicable federal, state, and local
safety regulations. ln our opinion, OSHA Type B soils should be encountered at this site during
excavation. OSHA recommends maximum allowable unbraced temporary excavation slopes of
1.251(H:V) for Type B soils for excavations up to 10 feet deep. Permanent cut and fill slopes are
anticipated to be stable at slope ratios as steep as 2H:1V (horizontal to vertical) under dry
conditions. New slopes should be revegetated as soon as possible after completion to minimize
erosion.
We recommend a minimum of l?feetof clearance between the top of excavation slopes and soil
stockpiles or heavy equipment or adjacent structures. This setback recommendation may be
revised by AGS once the project plans are available for review. lf braced excavations or shoring
systems are to be used or needed, they should be reviewed and designed by AGS. lt should be
noted that near-surface soils encountered at the site will be susceptible to some sloughing and
excavations should be periodically monitored by AGS's representative.
Project No: 0341-WS21
Junez7,2021
Page No: 13 of 16
It should be noted that the above excavation recommendations are commonly provided by local
consultants. The evaluation of site safety during construction, stability of excavated slopes and
cuts, and overall stability of the adjacent areas during and after construction is beyond our scope
of services. At your request, we can provide these services at an additional cost.
During construction in wet or cold weather, grade the site such that surface water can drain readily
away from the building areas, Promptly pump out or otherwise remove any water that may
accumulate in excavations or on subgrade surfaces and allow these areas to dry before resuming
construction. Berms, ditches and similar means may be used to prevent storm water from
entering the work area and to convey any water off-site efficiently.
lf earthwork is performed during the winter months when freezing is a factor, no grading fìll,
structural fill or other fill should be placed on frosted or frozen ground, nor should frozen material
be placed as fill. Frozen ground should be allowed to thaw or be completely removed prior to
placement of fill. A good practice is to cover the compacted fill with a "blanket" of loose fill to help
prevent the compacted fill from freezing overnight. The "blanket" of loose fill should be removed
the next morning prior to resuming fill placement.
During cold weather, foundations, concrete slabs-on-grade, or other concrete elements should
not be constructed on frozen soil. Frozen soil should be completely removed from beneath the
concrete elements, or thawed, scarified and re-compacted. The amount of time passing between
excavation or subgrade preparation and placing concrete should be minimized during freezing
conditíons to prevent the prepared soils from freezing. Blankets, soil cover or heating as required
may be utilized to prevent the subgrade from freezing.
GENERAL DRAINAGE
Proper surface drainage should be maintained at this site during and after completion of
construction operations. The ground surface adjacent to buildings should be sloped to promote
rapid run-off of surface water. We recommend a minimum slope of six inches in the first five
horlzontal feet for landscaped or graveled areas. These slopês should be maintained during the
service life of buildings. lf necessary, adequate interceptor drains should be installed on uphill
sides to intercept any surface water run-off towards the site.
Landscaping should be limited around building areas to either xeri-scaping, landscaping gravel,
or plants with low moisture requirements. No trees should be planted or present within 15 feet of
the foundations. lrrigation should be minimal and limited to maintain plants. Roof downspouts
should discharge on splash-blocks or other impervious surfaces and directed away from the
building. Ponding of water should not be allowed immediately adjacent to the building.
Project No: 0341-WS21
June 27,2021
Page No: 14 oî 16
It is important to follow these recommendations to minimize wetting or drying of the foundation
elements throughout the life of the facility. Construction means and methods should also be
utilized which minimize improper increases/decreases in the moisture contents of the soils during
construction.
Again, positive drainage away from the new structures is essential to the successful performance
of foundations and flatwork and should be provided during the life of the structure. Paved areas
and landscape areas within 10 feet of structures should slope at a minimum grade of 10H:1V
away from foundations. Downspouts from all roof drains, if any, should cross all backfilled areas
such that they discharge all water away from the backfill zones and structures. Drainage should
be created such that water is diverted away from building sites and away from backfill areas of
adjacent buildings.
GONCRETE CONSTRUCTION
Concrete sidewalks and any other exterior concrete flatwork around the proposed structure may
experience some differential movement and cracking. While it is not likely that the exterior
flatworks can be economically protected from distress, we recommend following techniques to
reduce the potential long-term movement:
. Scarify and re-compact at least 12 inches of subgrade material located immediately beneath
structures.
Avoid landscape irrigation and moisture holding plants adjacent to structures. No trees should
be planted or present within 15 feet of the foundations.
¡ Thicken or structurally reinforce the structures.
We recommend Type l-ll cement for all concrete in contact with the soil on this site. Calcium
chloride should not be added. Concrete should not be placed on frost or frozen soil. Concrete
must be protected from low temperatures and properly cured.
LIMITATIONS
Recommendations contained in this report are based on our field observations and subsurface
explorations, limited laboratory evaluation, and our present knowledge of the proposed
construction. lt is possible that soil conditions could vary between or beyond the points explored.
lf soil conditions are encountered during construction that differ from those described herein, we
should be notified so that we can review and make any supplemental recommendations
necessary. lf the scope of the proposed construction, including the proposed loads or structural
Project No: 0341-WS21
June27,2021
Page No: 15 of 16
a
locations, changes from that described in this report, our recommendations should also be
reviewed and revised by AGS.
Our Scope of Work for this project did not include a detailed geologic hazards evaluation of the
site. Therefore, any and all risks assoc¡ated with geologic hazards are assumed by the owner.
Otherwise, a detailed geologic hazards evaluation should be performed by AGS. Our Scope of
Work for this project did not include research, testing, or assessment relative to past or present
contamination of the site by any source. lf such contamination were present, it is very likely that
the exploration and testing conducted for this report would not reveal its existence. lf the Owner
is concerned about the potential for such contamination, additional studies should be undertaken.
We are available to discuss the scope of such studies with you. No tests were performed to detect
the existence of mold or other environmental hazards as it was beyond Scope of Work. Local
regulations regarding land or facility use, on and off-site conditions, or other factors may change
over time, and additional work may be required with the passage of time. Based on the intended
use of the report within one year from the date of report preparation, AGS may recommend
additionalwork and report updates. Non-compliance with any of these requirements by the client
or anyone else will release AGS from any liability resulting from the use of this report by any
unauthorized party. Client agrees to defend, indemnify, and hold harmless AGS from any claim
or liability associated with such unauthorized use or non-compliance.
ln this report, we have presented judgments based partly on our understanding of the proposed
construction and partly on the data we have obtained. This report meets professional standards
expected for reports of this type in this area. Our company is not responsible for the conclusions,
opinions or recommendations mãdê by others based on the data we have presented. Refer to
American Society of Foundation Engineers (ASFE) general conditions included in an appendix.
This report has been prepared exclusively for the client, its' engineers and subcontractors for the
purpose of design and construction of the proposed structure. No other engineer, consultant, or
contractor shall be entitled to rely on information, conclusions or recommendations presented in
this document without the prior written approval of AGS.
We appreciate the opportunity to be of service to you on this project. lf we can provide additional
assistance or observation and testing services during design and construction phases, please call
us at 1 888 276 4027.
Sincerely,
Sam Adettiwar, MS, PE, GE, P.Eng, M.ASCE
Senior Engineer
Attachments
Project No: 0341-WS21
June27,2O21
Page No: 16 of 16
FIGURES
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REFERENCE:
SITE PLAN PROVIDED BY
CLIENT
*$.2 888.2?6.402? - âúÊricmgossyices.com FIGURE 2: SCHEMATIC SITE PLAN
NOTE:
SCHEMATIC PLAN TO SHOWAPPROXIMATE SUBSURFACE EXPLORATION LOCATION ONLY;NOTSURVEYED.
LÉGEND:
*'TtGNATES suBsuRFAcE EX'L'RATT.N LocATroN, By AMERT.AN GEosERVrcEs, LLc. ,JUNE 2021 sEE EX'L.RATI.N
IOO II.I APPENDIX FOR FURTHER ÐETAILS.
AMERICAN CEOSERVICES
N
REFERENCE:
GARFIELD COUNTY
COLORADO GIS
888.276.{27 - åñcricangeosenicescom FIGURE 2: SGHEMATIC S¡TE PLAN
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LEGEND
Aspen'Gypsum Ar€a, Colorado, Parts of Eagle, Garfield, and PitkÍn Caunties (CO655)
Aspen-Gypsum Area, Colorado, Parts of Eagle, Garfield, and Pitkin Countles
{co6ss}
Map Unit $lame
Ansef-Anvik assoçiatittt, l2 to 25 percent
slopes
I Ansel-Anvik associat¡on. 25 to 45 percent
slapes
103.6 95.4Yo
Map Unit
Symbol
64 Jerry loem, 25 tÐ ı5 Fercent shlpes
66 Jerry-Millerlake loams, 6 tÐ 25 percent
slopes
Totðls for Area of tnterest
Asres in
AOI
t.7
1.4
3.5
Ð
Percent of
AOt
û.2o/û
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f .2o¡'s
108"6 100.Oq,b
N
REFERENCE:
WEB SOIL SURVEY
AÍ\1 Eit|{i\ Fi CL.ÙSl]{V ¡CLSVtf f¡i.? {ll jl - ratrrri{-r¡rËay,rJiir t(rm FIGURE 4: SOIL SURVEY MAP
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EG-14 Dune and sheet sand deposits
l.1j!r.i
E6-14 Cretaceaus and Tee-tiary Fcrmatlons
ffi
EG-1 4 Euep*rite Farmaticns
&
Â.MERICAN
N
ìEFERENCE:
]OLORADO GEOLOGICAL
JURVEY
*.€v å*C¿f l+út - Ë¡Yir¡tÌ!r:¿rtrinro¡
FIGURE 5: COLLAPSIBLE SOILS MAP
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ìEFERENCE:
]OLORADO LANDSL]DES
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FIGURE 6: LANDSLIDES HAZARD
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FIGURE 7: COAL SEAM HAZARD
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ìEFERENCE:
3ARFIELD COUNTY GIS ,{MERICAN#Såälf.{tl -ffifur$M(i$ffi FIGURE 8: FLOOD HAZARD
N
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ìEFERENCE:
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ìEFERENCE:
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N
FIGURE ll: TYPICAL DETAILSAMERICAN CEOSERVICES
888.276.402? - a¡ne.i.x¡gè.r''*d/
}IOTES:
A. ADD¡TIONAL REINFORCEMENT, #4 CONTINUOUS BAR,
BOTTOM OF FOOTING.
B. ADDITIONAL REINFORCEMENT, #4 4T48" C/C, TOPOF
FOOTING.RETAINING WALL DIMENSIONS AND
REINFORCEMENT TO BE DONE BY
PROJECT STRUCTURAT ENGINEER BASED
ON GEOTÊCHNICAL RECOMMENDATIONS.
G. REINFORCEMENTAS PER STRUCTURAL ENGINEER'S
DESIGN. AS A MINIMUM, USE #4 AT 48'C/C.
CONCRETE FOOTING TO BE
DIMENSIONED BY PROJECT
STRUCTURAL ENGINEER BASED ON
GEOTECHN ICAL RECOMMENDATIONS.
ADDITIONAL FOOTING REINFORCEMENT DETAIL
NEW ]NTERIOR
WALL
NOTES:
D. 4Od NA¡LS EVERY 24'THROUGH BOTTOM PLATE
¡NTO PRE-DRILLED HOLES OF THE FLOOR PLATE.
WALL FINISH
WALL BASE BOARD
NAILED ONLY TO BASE
PRESSURE TREATED 2'X4' BASE
PLATE SECURED WITH 3"
CONCRETE NAILS OR EQUIVALENT
PLATE;TOP lS FREE
3" MIN VO¡D SPACE
SPACER.SAME THICKNESS AS
WALL FINISH MATERIAL
CONCRETE BASEMENT SLAB
.FLOAT' (FLOATING WALL DETAIL)
D
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FIGURE 12: DRAINAGE DETAILSAMERICAN CEOSERVICES
888.276-427' incricùrgcoscrrìccscomtt'"'il/
t:
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1,
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FLEXIBLE ADHESIVE EQUIVALENT,
4'ABOVE GROUND;
MAINTAIN LEAK-FREE
COMPACTED EARTH BACKFILUSO¡L CAP
(DO NOT USE rF STEM WALL lS
DESIGNED AS A RETAINING WALL. IN
CASE OF RETAINING WALL, USE
FREE.DRAINING CRUSHED ROCK FILL TO
AVOID HYSROSTATIC PRESSURE.
FOUNDATION/STEM WALL
POLYETHYLENE FILM GLUED TO
FOUNDATION WALL AND EXTENDED
BELOWTHE DRAIN AS SHOWN
OVER.EXCAVATION
(sEE NOTE B)
LEAK-FREE AND ADEQUATE
CAPACITY DOWNSPOUTS
MINIMUM 3" THICK
DECORATIVE GRAVEL,
ROCK OR BARK I.AYER
AT LEAST 4 FT LONG
20 MIL THICK POLY
SHEET LINERAT LEAST
4FT LONG; EXTEND 4'
ABOVE GROUND & 36'
BELOWGROUND
DOWNSPOUT & MOISTURE BARRIER DETAIL
- EXTEND DOWNSPOUT
BEYOND
DECORATIVE LAYER,
10H:1V GRADE;
WTHOUT CAUSING
ADVERSE IMPACT
ON ADJACENT
PROPERTIES; DISCHARGE
ONTO SPLASH BLOCKS.
6"MN L-
L OFFSET FORANY
SPRINKLER
HEADS; PART CIRCLE
SPRAYING
AWAY FROM BUILDING
SLOPE TO DRAIN AWAY
FROM STRUCTURE, 10H:1V
(sEE DOWNSPOUT DETAIL)
MIRAFIl4O N F]LTER
FABRIC OR EQUIVALENT
I
I:SLAB-ON-GRADE WITH
12'MINI
EXPANSION JOINTS OR
6" MIN
FREE.DRAINING
CLEAN CRUSHED
ROCK/GRAVEL
EXCAVATED TRENCH,
NEARVERTICALTO
0.5H:lV
\.,SUBGRADE, IN-SITU SOIQ
(sEE NOTE C)
PERIMETER OR FOUNDATION DRAIN DETAIL
NOTES:4.4-INCH DIAMETER PERFORATED PIPE PLACED 2'ABOVE DRAIN SUBGRADE EMBEDDED lN FREE-DRAINING GRAVEL OR
CRUSHED ROCK ENVELOPE WITH2O/O GRADE TO SUMP PIT OR DISCHARGED TO A SUITABLE RECEPTACLE SUCH THATON.SITEAS
WELL AS OFF.SITE STABILITY IS NOT ADVERSELY IMPACTED. B. DEPTH BASED ON OPEN HOLE INSPECTION, FOR SHALLOW
FOUNDATION OPT¡ON. C. ALL FOUNDATION OR OVER.EXCAVATED SUBGRADES MUST BE INSPECTED AND APPROVED BY A
GEOTECHNICAL ENGINEER.
.,i¡
4..ia
1,
ai
+
APPENDIX
B1
Project Number 0341-CS21 Drill Rig: SoilAuger & Wllliamson Drive Probe
GeologisVEngineer SMA Ground Elevation See Figures
Date Drilled 06-18-2021 ïotal Depth of Exploration 6.25 Feet
Borehole Diameter 4 OD lnches Depth to Water Not encountered
Ëtr0J
.9
Ctt!
o
Description / Lithology
oorÈ
E{ra
CLoft
o
o.
E
G(t,
c
oo
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s
Lo
o(,o
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s
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=
la-(,
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o
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s
JÀ
s
JJ
s
o
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co
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oo
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"'/-'írj
'r¡r''t,""¡
'r')r,
,t4,ír
//-/'
'íri
-1,
1"".
:í,,
-fr
CL
GC/
CL
SlLry SANDY CLAY, brown to orange, gray,
medium stiff to very stiff, medium plasticity
Possibly Shale below 4.5 feet, completely
weathered, medium plasticity
End of Borehole at 6.25 feet. Groundwater
seepage was not encountered during or at
the completion of drilling. Soil description
based on exploration, soils and geologic
maps reviews, and localexperience. See
figures and appendix for more information.
1.2â-
1.5-
-3..75-
--5.0-
6.25
8-10-1 I
50+
36,2C
1.ïYo
@
500
psf
XX
Y
\{
XXX
/(
t\XX
. 1v *:**s"#"crosERVrcES Page 1
82
0341-CS21Project Number Drill Rig: Soil Auger & Wllliamson Drive Probe
GeologisUEngineer SMA Ground Elevation See Figures
06-18-2021Date Drilled Total Depth of Exploration 6.00 Feet
Borehole Diameter 4 OD lnches Not encounteredDepth to Water
EtöJ
.9
ÊL
.ELo
Description / Lithology
rl.-oorÈ
.G{.r
CLoo
-9
CL
E
fEv,
c¿oo
ìooþo.
an
s
Lo
o(,o
É.
s
oLãflo
o
=
la-(,
o.
oô
s
JÀ
s
JJ
s
o
=(t,
co
fl
-9
CL
Eoo
il;
r"l',ií:
,/,j
'rt-',r:i
'./,
lt
'4
,"-r/.
n
'aj
)"'-
í-j
,/r'..r,.-
'.'ta"
CL
GCr
CL
SILTY SANDY CLAY, brown to orange, gray,
medium stiff to very stiff, medium plasticity
Possibly Shale below 5.0 feet, completely
weathered, medium plasticity. End of Borehole
at 6.00 feet. Groundwater seepage was not
encountered during or at the completion of
drilling. Soil description based on exploration,
soils and geologic maps reviews, and
local experience. See figures and appendix
for more information.
1.2â-
1.5-
-3.75-
-s.0-
6.25
10-11-19
50+
\/,
X\.,
\l
30,18
X
X
Xl(X
Page 1
AMERICAN CEOSERVICES
886¿?6.@? - dèdqñ*ft¡cß@ñv
*y AMERICAN
CEOSERVICES
DESCRIPTIVE TERMINOLOGY & SOIL CLASSIFICATION
UNIFIED SOIL CLASSIFICATION SYSTEM
LABORATORY CLASSIFICATION CRITERIAUNIFIED SOIL CLASSIFICATION AND SYMBOL CHART
COARSE-GRAINED SOILS
(more than 50% of material is larger than No. 200 sieve size.)
Well-graded gravels, gravel-sand
mixtures, little or no fines ", = +l sreater rhan 4: cc = ffi *r'een 1 and 3
GWGW
GP Poorly-graded gravels, gravel-sand
mixtures, little or no lines GP Not meeting all gradation requirements for GW
GM Atterberg limits below'.A'
line or P.l. less than 4GMSilty gravels, gravel-sand-silt mixtures
GC Atterberg limits above "A
line with P.l. greater than
Above'4" line with P.l. between
4 and 7 are borderline cases
requiring use of dual symbolsGC
Clean Gravels than 5%
Gravels with fines lhan 12lo
GRAVELS
More than 507o
of coarse
fraction larger
than No.4
sieve size
Clayey gravels, gravel-sand-clay
mixtures
C = ?oo oreater than 4: C^ =
Dgo
betueen 1 and 3" D.,o " D1orD6oSWSWWell-graded sands, gravelly sands,
little or no fines
SP Poorly graded sands, gravelly sands,
little or no fines Sp Not meeting all gradation requirements for GW
SM Silty sands, sand-silt mixtures Atterberg
line or Pl.SM limits below'A'
less than 4
sc
Limits plotting in shaded zone
with P.l. between 4 and 7 are
borderline cases requiring use
of dual symbols.SC
Clean Sands than 5%
Sands with fines
SANDS
50% or more
of coarse
fraction smaller
than No. 4
sieve size
Clayey sands, sand-clay mixtures
FINE-GRAINED SOILS
(50% or more of material is smaller than No. 200 sieve size.)
ML
lnorganic silts and very fine sands, rock
flour, silty of clayey fine sands or clayey
silts with slight plasticity
PLASTICITY CHART
CL
lnorganic clays of low to medium
plasticity, gravelly clays, sandy clays,
silty clays, lean clays
SILTS
AND
CLAYS
Liquid limit
less than
50%
OL Organ¡c s¡lts and organic silty clays of
low plasticity
MH
lnorganic silts, micaceous or
diatomaceous fine sandy or silty soils,
elastic silts
CH lnorganic clays of high plastic¡ty, fat
clays
S¡LTS
AND
CLAYS
Liquid limit
50%
or greater
OH Organic clays of medium to high
plasticity, organic silts
60
lelsog
x40l¡loZzo
920
Þ'-t,
710À
CH
A
t=
CL MH,,OH
ML&CLlLitL
0 10 20 30 40 50 60 70 80 90 100
LTQUTD Lrmrr GL) (%)
0
Peat and other highly organic soilsHIGHLY
ORGANIC
sotLs
l,;
PT
DESCRIPTIVE TERMINOLOGY & SOIL CLASSIFICATION
TESTING DEFINITIONS FOR CONSISTÊNCY OF COHESIVE SOILS
EXPLORATION LOGS
CONSISTENCY sTP (BPF)
DD
WD
MC
PL
LL
PI
oc
S
SG
c
o
QU
DRY DENSITY (PCF)
wET DENSTTY (PCF)
MOTSTURE CONTENT (%)
PLASTTC LrMrr (%)
LTQUID LrMrr (%)
PLASTICITY INDEX
oRGANTC CONTENT (%)
SATURATI ON PERCENT f/o)
SPECIFIC GRAVITY
coHEsroN
ANGLE OF INTERNAL FRICTION
UNCONFINED COMPRESSION
STRENGTH
PERCENT PASSING THE #2OO SIEVE
CALIFORNIA BEARING RATIO
VANE SHEAR
POCKET PENETROMETËR
DRIVE PROBE
STANDARD PENETRATION TEST
BLOWS PER FOOT (N VALUE)
SHELBY TUBE SAMPLE
GROUNDWATER
ROCK QUALIry DESIDNATION
TEST PIT
BORING
HAND AUGER
VERY SOFT
SOFT
MEDIUM STIFF
STIFF
VERY STIFF 2.0 - 4.0
HARD 30+OVER4.O
RELATIVE DENSITY OF COHESIONLESS SOILS
DENSITY SPT (BPF)
VERY LOOSE o-4
LOOSE 5-10
MEDIUM DENSE 11-30
DENSE 31 -50
VERY DENSE 50+
PARTICLE SIZE IDENTIFICATION
#200 =
CBR =
VS=
PP=
DP=
SPT =
BPF =
SH=
GW
RQD =
TP=
þ=
HA=
NAME DIAMETER
(rNcHES)
SIEVE NO.
ROCK BLOCK
BOULDER
COBBLE
GRAVEL
COURSE
FINE NO.4
SAND
NO.10
MEDIUM NO.40
FINE .425 MM NO. 200
SILT .075 MM
CLAY <0.005 MM
GRAIN SIZE
FINE
GRAINED
<0.04 tNcH FEW GRAINS ARE
DISTINGUISHABLE IN THË
FIELD ORWITH HAND LENS.V
-
GRoUNDWATERLEVEUSEEPAGE
ENCOUNTERED DURING EXPLORATION
MEDIUM
GRAINED
0.04-0.2 lNcH GRAINS ARE
DISTINGUISHABLE WITH THE
AID OF A HAND LENS.
Y
COARSE
GRAINED
MOST GRAINS ARE
DISTINGUISHABLE WITH THE
NAKED EYE..-
STATIG GRoUNDWATER LEVEL WITH
DATE MEASURED
0-1
PP CrSF)
1.0 - 2.0
0.25 - 0.5
0.5 - 1.0
16-30
s-15
2-4
LESS THAN 0.25
5-8
>120
12-120
3-12
1t4 - 3t4
314-3
4.75 MM
2.OMM
0.04-0.2 rNcH
DESCRIPTIVE TERMINOLOGY & SOIL CLASSIFICATION
SPT EXPLORATIONS:
STANDARD PENETRATION TESTING IS
PERFORMED BY DRIVING A 2 - INCH O.D. SPLIT.
SPOON INTO THE UNDISTURBED FORMATION AT
THE BOTTOM OF THE BORING WITH REPEATED
BLOWS OF A 140 - POUND PIN GUIDED HAMMER
FALLING 30 INCHES. NUMBER OF BLOWS (N
VALUE) REQUIRED TO DRIVE THE SAMPLER A
GIVEN DISTANCE WAS CONSIDERED A MEASURE
OF SOIL CONSISTENCY.
SH SAMPLING:
SHELBY TUBE SAMPLING IS PERFORMED WITH A
THIN WALLED SAMPLER PUSHED INTO ÏHE
UNDISTURBED SOIL TO SAMPLE 2.0 FEET OF
soL.
AIRTRACK EXPLORATION:
TESTING IS PERFORMED BY MEASURING RATE
OF ADVANCEMENT AND SAMPLES ARE
RETRIEVED FROM CUTTINGS.
HAND AUGUR EXPLORATION:
TESTING IS PREFORMED USING A 3.25'
DIAMETER AUGUR TO ADVANCE INTO THE EARTH
AND RETRIEVE SAMPLES.
DRIVE PROBE EXPLORATIONS:
THIS "RELATIVE DENSITY' EXPLORATION DEVICE
IS USED TO DETERMINE THE DISTRIBUTION AND
ESTIMATE STRENGTH OFTHE SUBSURFACE SOIL
AND DECOMPRESSED ROCK UNITS. THE
RESISTANCE TO PENETRATION IS MEASURED IN
BLOWS.PER-1I2FOOT OF AN I1-POUND HAMMER
WHICH FREE FALLS ROUGHLY 3.5 FEET DRIVING
THE 0.5 INCH DIAMETER PIPE INTO THE GROUND.
FOR A MORE DETAILED DESCRIPTION OF THIS
GEOTECHNICAL EXPLORATION METHOD, THE
SLOPE STABILIry REFERENCE GUIDE FOR
NATIONAL FORESTS IN THE UNITED STATES,
VOLUME I, UNITED STATES DEPARTMENT OF
AGRICULTURE, EM-7170-13, AUGUST 1994, P. 317-
321.
CPT EXPLORATION
CONE PENETROMETER EXPLORATIONS CONSIST
OF PUSHING A PROBE CONE INTO THE EARTH
USING THE REACTION OF A 2O-TON TRUCK. THE
coNE RESTSTANCE (OC)AND SLEEVE FRICTION
(FS) ARE MEASURED AS THE PROBE WAS
PUSHED INTO THE EARTH. THE VALUES OF QC
AND FS (IN TSF) ARE NOTED AS THE LOCALIZED
INDEX OF SOIL STRENGTH.
ANGULARIry OF GRAVEL & COBBLES
ANGULAR
SUBANGULAR
SUBROUNDED
COARSE PARTICLES HAVE SHARP
ËDGES AND RELATIVELY PLANE SIDËS
WITH UNPOLISHED SURFACES.
COARSE GRAINËD PARTICLES ARE
SIMILAR TO ANGULAR BUT HAVE
ROUNDED EDGÉS.
COARSE GRAINED PARTICLES HAVE
NEARLY PLANE SIDES BUT HAVE WELL
ROUNDED CORNERS AND EDGES.
COARSE GRAINED PARTICLES HAVE
SMOOTHLY CURVED SIDES AND NO
EDGES.
ROUNDED
SOIL MOISTURE MODIFIER
DRY
MOIST
WET
WEATHERED STATE
FRESH
SLIGHTLY
WEATHERED
MODERATELY
WEATHERED
HIGHLY
WEATHERED
COMPLETELY
WEATHERED
RESIDUAL SOIL
ABSENCE OF MOISTURE;DUSTY, DRY
TO TOUCH
DAMP BUT NO VISIBLE WATER
VISIBLE FREE WATER
NOVISIBLE SIGN OF ROCK MATERIAL
WEATHERING; PERHAPS SLIGHT
DISCOLORATION IN MAJOR
DISCONTINUITY SURFACES.
INDICATES
WEATHERING OF ROCK MATERIALAND
DISCONTINUITY SURFACES. ALL THE
ROCK MATERIAL MAY BE DISCOLORÊD
BYWEATHERINGAND MAYBE
SOMEWHAT WEAKER EXTERNALLY
THAN ITS FRESH CONDITION,
LESS THAN HALF OF THE ROCK
MATERIAL IS DECOMPOSED AND/OR
DISINTEGRATED TO SOIL. FRESH OR
DISCOLORED ROCK IS PRESENT EITHER
AS A CONTINUOUS FRAMEWORK OR AS
CORE STONES.
ì
MORE THAN HALF OF THE ROCK
MATERIAL IS DECOMPOSED AND/OR
DISINTEGRATED TO SOIL. FRESH OR
DISCOLORED ROCK IS PRESENT EITHER
AS DISCONTINUOUS FRAMEWORK OR
AS CORE STONE.
ALL ROCK MATERIAL IS DECOMPOSED
AND/OR DISINTEGRATED TO SOIL. THE
ORIGINAL MASS STRUCTURE IS STILL
LARGELY INTACT.
ALL ROCK MATERIAL IS CONVERTEDTO
SOIL. THE MASS STRUCTURE AND
MATERIAL FABRIC IS DESÏROYED,
THERE IS A LARGE CHANGE IN VOLUME,
BUT THE SOIL HAS NOT BEEN
YTRANSPORTED,
Map Unit Description: Ansel-Anvik association, 25lo 45 percent slopes--Aspen-Gypsum Area,
Colorado, Parts of Eagle, Garfield, and Pitkin Counties
Aspen-Gypsum Area, Colorado, Parts of Eagle,
Garfield, and Pitkin Counties
9-Ansel-Anvik assoc¡at¡on,25 to 45 percent slopes
Map Unit Setting
National map unit symbol: jq7n
Elevation: 7,500 to 9,500 feet
Mean annual precipitation: 18 to 22 inches
Mean annual air temperature: 38 to 40 degrees F
Frost-free period: 70 to 80 days
Farmland classification; Not prime farmland
Map Unit Composition
Ansel and similar soils: 7A percent
Anvik and similar so/s; 20 percent
Minor components; 10 percent
Estimafes are based on obseruations, descriptions, and fransecfs of
the mapunit.
Description of Ansel
Setting
Landform: Fans, hills
Landform position (two-dimensional) : Footslope
Landform position (three-dimensional): Lower third of mountainflank
Down-slope shape: Linear
Across-s/op e sh ape : Linear
Parent material: Mixed alluvium
Typical profile
H1 - 0 to 23 inches; loam
H2 - 23 to 48 inches: stony clay loam
H3 - 48 to 60 inches; clay loam
Properties and qualities
S/ope:25 to 45 percent
Depth to restrictive feature: More than 80 inches
Drainage c/ass; Well drained
Runoff class: High
Capacity of the most limiting layer to transmit water
(Ksat): Moderately high (0.20 to 0.60 in/hr)
Depth to water table; More than 80 inches
Frequency of flooding: None
F req ue n cy of pondtng: N one
Available water capacity: High (about 9.3 inches)
lnterpretive groups
Land capability classification (irrigated); None specifìed
Land capability classification (nonirrigated): 7e
Hydrologic Soil Group: C
Other vegetative classification; Spruce-Fir (null 21)
USDA
=
Natural Resources
Gonservation Seruice
Web Soil Survey
National Cooperative Soil Survey
6t1712021
Page 1 of2
Map Unit Description: Ansel-Anvik association, 25 to 45 percent slopes--Aspen-Gypsum Area,
Colorado, Parts of Eagle, Garfield, and Pitkin Counties
Hydricsoilratrng: No
Description of Anvik
Setting
Landform: Mountain slopes, fans
Landform position (three-dimensional): Lower third of mountainflank
Down-slope shape: Linear
Across-slop e shape : Linear
Parent mater¡al: Mixed alluvium andlor mixed colluvium
Typical profile
Hl - 0 to 12 inches: loam
H2 - 12 to 18 inches.' sandy loam
H3 ^ 18 to 42 inches; cobbly clay loam, clay loam
H3 - 18 to 42 inches: cobbly clay loam
H4 - 42 to 60 inches:
Properties and qualit¡es
S/ope: 25 to 45 percent
Depth to restrictive feature: More than 80 inches
Drainage c/ass; Well drained
Runoff class; High
Capacity of the most limiting layer to transmit water
(Ksat): Moderately high to high (0.20 to 2.00 in/hr)
Depth to water fable; More than 80 inches
Frequency of flooding: None
F req ue ncy of ponding; None
Available water capactfy.Very high (about 12.6 inches)
lnterpretive groups
La nd ca pabil ity cl a ssification (irrigated).' None specified
Land capability classification (nonirrigated) : 7 e
Hydrologic Soil Group: B
Other vegetative classification; Spruce-Fir (null 21)
Hydric so/ rafing; No
Minor Components
Other soils
Percent of map unit: 1O percent
Hydric sol/ rafing; No
Data Source lnformation
Soil Survey Area: Aspen-Gypsum Area, Colorado, Parts of Eagle, Garfield, and
Pitkin Counties
SurveyArea Data: Version 11, Jun 5,2020
USDA
-
Natural Resources
Conse¡vatlon Service
Web Soil Survey
National Cooperative Soil Survey
6t17t2021
Page2oÍ2
IMPORTANT INFORMATION ABOUT YOUR
GEOTECHNICAL ENGINEERING REPORT
As the client of a consulting geotechnical
engineer, you should know that site subsurface
conditions cause more construction problems than
any other factor. ASFE/the Association of
Engineering Firms Practicing in the Geosciences
offers the following suggestions and observations
to help you manage your risks.
A GEOTECHNICAL ENG.NEERING REPORT IS
BASED ON A UNIQUE SET OF PROJECT-
SPECIFIC FACTORS Your geotechnical
engineering report is based on a subsurface
exploration plan designed to consider a unique set
of project-specific factors. These factors typically
include: the general nature of the structure
involved, its size, and configuration; the location of
the structure on the site; other improvements, such
as access roads, parking lots, and underground
utilities; and the additional risk created by scope-
of-service limitations imposed by the client. To
help avoid costly problems, ask your geotechnical
engineer to evaluate how factors that change
subsequent to the date of the report may affect the
report's recommendations.
Unless your geotechnical engineer indicates
otherwise, do not use your geotechnical
engineering report:
MOST GEOTECHN¡CAL FIND¡NGS ARE
PROFESSIONAL JUDGMENTS
Site exploration identifies actual subsurface
conditions only at those points where samples are
taken. The data were extrapolated by your
geotechnical engineer who then applied judgment
to render an opinion about overall subsurface
conditions. The actual interface between materials
may be far more gradual or abrupt than your
report indicates, Actual conditions in areas not
sampled may differ from those predicted in your
report. While nothing can be done to prevent such
situations. you and your geotechnical engineer
can work together to help minimize their impact.
Retaining your geotechnical engineer to observe
construction can be particularly beneficial in this
respect.
. when the nature of the proposed structure is
changed. for example, if an office building will
be erected instead of a parking garage, or a
refrigerated warehouse will be built instead of
an unrefrigerated one;¡ when the size, elevation. or configuration of the
proposed structure is altered;
o when the location or orientation of the proposed
structure is modified;¡ when there is a change of ownership; or .for
application to an adjacent site.
Geotechnical engineers cannot accept
responsibility forþroblems that may occur if they
are not consulted after factors considered in their
report's development have changed.
A REPORT'S RECOMMENDATIONS CAN ONLY
BE PRELIMINARY
The construction recommendations included in
your geotechnical engineer's report are
preliminary, because they must be based on the
assumption that conditions revealed through
selective exploratory sampling are indicative of
actual conditions throughout a site.
Because actual subsurface conditions can be
discemed only during earthwork, you should retain
your geo- technical engineer to observe actual
conditions and to finalize recommendations. Only
the geotechnical engineer who prepared the report
is fully familiar with the background information
needed to determine whether or not the report's
recommendations are valid and whether or not the
contractor is abiding by applicable
recommendations. The geotechnical engineer who
developed your report cannot assume
responsibility or liability for the adequacy of the
report's recommendations if another party is
retained to observe construction.
SUBSURFACE CONDITIONS CAN CHANGE A
geotechnicalengineering report is based on condi-
tions that existed at the time of subsurface
exploration. Do not base construction decisions on
a geotechnical engineering report whose
adequacy may have been affected by time. Speak
with your geotechnical consult- ant to learn if
additional tests are advisable before construction
starts. Note, too, that additionaltests may be
required when subsurface conditions are affected
by construction operations at or adjacent to the
site, or by natural events such as floods,
earthquakes, or ground water fluctuations. Keep
your geotechnical consultant apprised of any such
events.
GEOTECHNICAL SERVICES ARE PERFORMED
FOR SPECIFIC PURPOSES AND PERSONS
Consu ltin g geotechnical engi neers prepare reports
to meet the specific needs of specific individuals. A
report prepared for a civil engineer may not be
adequate for a construction contractor or even
another civil engineer. Unless indicated otherwise,
your geotechnical engineer prepared your report
expressly for you and expressly for purposes you
indicated. No one other than you should apply this
report for its intended purpose without first
conferring with the geotechnical engineer. No
party should apply this report for any purpose
other than that originally contemplated without first
conferring with the geotechnical engineer.
GEOENVIRONMENTAL CONCERNS ARE NOT
AT ISSUE
Your geotechnical engineering report is not likely
to relate any findings, conclusions, or
recommendations
about the potential for hazardous materials
existing at the site. The equipment, techniques,
and personnel used to perform a
geoenvironmental exploration d iffer substantially
from those applied in geotechnical engineering.
Contamination can create major risks. lf you have
no information about the potential for your site
being contaminated. you are advised to speak with
your geotechnical consultant for information
relating to geoenvironmental issues.
A GEOTECHNICAL ENGINEERING REPORT IS
SUBJECT TO MISINTERPRETATION Costly
problems can occur when other design profes-
sionals develop their plans based on
misinterpretations of a geotechnical engineering
report. To help avoid misinterpretations, retain
your geotechnical engineer to work with other
project design professionals who are affected by
the geotechnical report. Have your geotechnical
engineer explain report implications to design
professionals affected by them. and then review
those design professionals' plans and
specifications to see how they have incorporated
geotechnical factors. Although certain other design
professionals may be fam- iliar with geotechnical
concerns, none knows'as much about them as a
competent geotechnical engineer.
BOR¡NG LOGS SHOULD NOT BE SEPARATED
FROM THE REPORT Geotechnical engineers
develop final boring logs based upon their
interpretation of the field logs
(assembled by site personnel) and laboratory
evaluation of field samples. Geotechnical
engineers customarily include only final boring
logs in their reports. Final boring logs should not
under any circumstances be redrawn for inclusion
in architectural or other design drawings. because
drafters may commit enors or omissions in the
transfer process. Although photographic
reproduction eliminates this problem, it does
nothing to minimize the possibility of contractors
misinterpreting the logs during bid preparation.
When this occurs. delays. disputes. and
unanticipated costs ara the all-too-frequent result.
To minimize the likelihood of boring log
misinterpretation, give contractors ready access to
the complete geotechnical engineering report
prepared or authorized for their use. (lf access is
provided only to the report prepared for you, you
should advise contractors of the report's
limitations. assuming that a contractor was not one
of the specific persons for whom the report was
prepared and that developíng
construction cost estimates was not one of the
specific purposes for which it was prepared. ln
other words. while a contractor may gain important
knowledge from a report prepared for another
party, the contractor would be well-advised to
discuss the report with your geotechnical engineer
and to perform the additional or alternative work
that the contractor believes may be needed to
obtain the data specifically appropriate for
construction cost estimating purposes.) Some
clíents believe that it is unwise or unnecessary to
give contractors access to their geo- technical
engineering reports because they hold the
mistaken impression that simply disclaiming
responsibility for the accuracy of subsurface
information always insulates them from attendant
liability. Providing the best available information to
contractors helps prevent costly construction
problems. lt also helps reduce the adversarial
attitudes that can aggravate problems to
disproportionate scale.
READ RESPONSIBILITY CLAUSES CLOSELY
Because geotechnical engineering is based
extensively on judgment and opinion, it is far less
exact than other design disciplines. This situation
has resulted in wholly unwarranted claims being
lodged against geotechnical engineers. To help
prevent this problem, geotechnical engineers have
developed a number of clauses for use in their
contracts, reports, and other documents.
Responsibility clauses are not exculpatory clauses
designed to transfer geotechnical engineers'
liabilities to other parties. lnstead, they are
definitive clauses that identify where geotechnical
engineers' responsibilities begin and end. Their
use helps all parties involved recognize their
individual responsibilities and take appropriate
action. Some of these definitive clauses are likely
to appear in your geotechnicalengineering report.
Read them closely. Your geotechnical engineer
will be pleased to give full and frank answers to
any questions.
RELY ON THE GEOTECHNICAL ENGINEER
FOR ADDITIONAL ASSISTANCE
Most ASFE-member consulting geotechnical
engineering firms are familiar with a variety of
techniques and approaches that can be used to
help reduce risks for all parties to a construction
project, from design through construction. Speak
with your geotechnical engineer not only about
geotechnical issues, but others as well, to learn
about approaches that may be of genuine benefit.
You may also wish to obtain certain ASFE
publications. Contact a member of ASFE of ASFE
for a complimentary directory of ASFE
publications.
ASFE
8811 Colesville Road/Suite G106/Silver Spring, MD 20910
Telephone: 301 I 565-2733 Facsimile: 30 1 /589 -2017
Subsurfuce Explorotions
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toundafion E
lock fíle
Eorfhquoke
0eoslruuctu esrgn
Povement Design
Droinoge Evoluolions
Groundwqter Studies
Environmenlal Assefs
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ûeo
Retoining
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