HomeMy WebLinkAboutB15-0252_R156007R1 VailClubhouse 150828_1452534060.pdf
Subsurface Exploration Program and
Revised Geotechnical Report
Proposed Golf Course Clubhouse Additions
Vail, Colorado
Prepared For:
Town of Vail
75 S. Frontage Road
Vail, Colorado 81657
Attention: Mr. Tom Kassmel
Job Number: 15-6007R1 August 28, 2015
TABLE OF CONTENTS
Page
Purpose and Scope of Study ...................................................................................... 1
Proposed Construction ................................................................................................ 1
Site Conditions ............................................................................................................ 2
Regional and Project Site Geology and Potential Hazards .......................................... 2
Seismic Classification ................................................................................................. 2
Subsurface Exploration ............................................................................................... 3
Laboratory Testing ...................................................................................................... 4
Subsurface Conditions ................................................................................................ 4
Geotechnical Considerations For Design .................................................................... 5
Shallow Foundation Systems ...................................................................................... 5
Slab-On-Grade Concrete Floor ................................................................................... 7
Project Earthwork ........................................................................................................ 9
Excavation Considerations ........................................................................................ 12
Lateral Earth Pressures ............................................................................................ 13
Water Soluble Sulfates .............................................................................................. 15
Soil Corrosivity .......................................................................................................... 15
Surface Drainage ...................................................................................................... 17
Subsurface Drainage ................................................................................................ 19
Golf Course Parking Lot ............................................................................................ 22
Exterior Flatwork ....................................................................................................... 28
Closure ...................................................................................................................... 31
Locations of Test Holes .................................................................................... Figure 1
Log of Test Hole ............................................................................................... Figure 2
Legend and Notes ............................................................................................ Figure 3
Consolidation Test Result ................................................................................ Figure 4
Typical Underdrain Detail ................................................................................. Figure 5
Summary of Laboratory Test Results ................................................................ Table 1
Proposed Golf Course Clubhouse Additions
1610 Sunburst Drive
Vail, Colorado
Job No. 15-6007R1 Ground Engineering Consultants, Inc. Page 1
PURPOSE AND SCOPE OF STUDY
This revised report presents the results of a subsurface exploration program performed
by GROUND Engineering Consultants, Inc. (GROUND) to develop geotechnical
recommendations for the proposed improvements to the Vail Golf Course Clubhouse
and surrounding parking lot at the Vail Golf Course located at 1610 Sunburst Drive, Vail,
Colorado. Our study was conducted in general accordance with GROUND’s Proposal
No. 1110-1592, dated November 3, 2011 and email request for an updated report from
July 9, 2015. Report update items originally included additional discussion regarding
groundwater conditions encountered during construction, lack of minimum foundation
frost protection soil cover, and pavements. This revision includes additional subsurface
drainage design criteria, analysis and discussion, and updated lateral earth pressures.
A report for the proposed improvements was originally provided under Job No. 11-6019
and dated December 20, 2011.
A field exploration program was conducted to obtain information on subsurface
conditions at the site. Material samples obtained during the subsurface exploration were
tested in our laboratory to provide data on the classification and engineering
characteristics of the on-site soils. The results of the field exploration and laboratory
testing are presented herein.
This report has been prepared to summarize the data obtained and to present our
conclusions and recommendations based on the proposed construction and the
subsurface conditions encountered. Design parameters and a discussion of
geotechnical engineering considerations related to construction are included herein.
PROPOSED CONSTRUCTION
We understand that proposed construction will consist of the remodel of a two-story
building with a footprint of approximately 15,600 SF and associated sitework. The new
foundation construction will consist of a spread footing and grade beam foundation
system with a slab-on-grade. The building will consist of limited structural steel framing
with a wood roof system. Site improvements are anticipated to include site grading,
over-excavation, utility installations, drainage improvements, concrete flatwork/paving
and asphalt paving. Clubhouse addition and column/pad loads are anticipated to be
light, typical of this type of construction. If the proposed construction differs significantly
from that described above, GROUND should be notified to re-evaluate the
recommendations contained herein.
Proposed Golf Course Clubhouse Additions
1610 Sunburst Drive
Vail, Colorado
Job No. 15-6007R1 Ground Engineering Consultants, Inc. Page 2
SITE CONDITIONS
The existing clubhouse is a two-story restaurant / commercial facility located east of
Sunburst Drive and west of the golf course with parking areas to the south (See Figure
1.) The surrounding area has been developed / graded for commercial use and parking
with landscaped grass, bushes, and pine trees. The golf course surrounds the
clubhouse to the north and east. Several ponds and ‘wetlands’ areas are located within
the golf course, Gore Creek is located north of the clubhouse. The site is located at the
valley bottom and the general topography at the site is nearly level or gently sloping at
approximately 5 percent descending towards the northwest.
REGIONAL, PROJECT SITE GEOLOGY AND POTENTIAL HAZARDS
The project area is located near the northern tip of the north-trending Sawatch Range
anticlinal uplift, a geologic structure that developed during the Laramide orogeny (about
40 to 80 million years ago), and east of the Colorado evaporate region and Burns
Syncline. Surficial deposits at the project site are mapped as fluvial (river) (Qaf) and
glacial outwash sands and gravels (Qg). Underlying bedrock is Pennsylvanian Age
Minturn Formation.
The closest geologically young faults exhibiting movement in the last 15,000 years that
are considered capable of generating large earthquakes are located in the northern
section of the Williams Fork Mountains fault zone, about 20 miles north of the project
site.
The shallow water table, wetlands, and proximity of Gore Creek suggest flooding may
occur at the clubhouse during times of heavy rainfall or snowmelt.
Although rockfall, landslide, and avalanche hazards do occur in the area, in our opinion,
we consider the possibility of such a geologic hazard affecting the project site to be low
compared to areas of closer proximity to the surrounding hillsides.
SEISMIC CLASSIFICATION
Utilizing the USGS’s Earthquake Ground Motion Tool v.5.1.0 and the approximate site
latitude/longitude coordinates, the project site is indicated to be subject to an SDS value
of 0.282g and an SD1 value of 0.068g. Compared with other regions of the Western
United States, recorded earthquake frequency in the project vicinity is relatively low.
Proposed Golf Course Clubhouse Additions
1610 Sunburst Drive
Vail, Colorado
Job No. 15-6007R1 Ground Engineering Consultants, Inc. Page 3
In the absence of actual shear wave velocity testing/analysis or deep drilling, GROUND
estimates that a Seismic Site Class D according to the 2006/2009 IBC classification
(Table 1613.5.2) is applicable to the site. In the event that the owner desires to utilize
Site Class C for design, according to the 2006/2009 IBC, actual downhole seismic shear
wave velocity testing and/or exploration to subsurface depths of at least 100 feet, should
be performed. Based on available data, we consider the likelihood of realizing a Site
Class C to be low.
SUBSURFACE EXPLORATION
The subsurface exploration for the project site was conducted on November 10, 2011.
One test hole (Test Hole 1) was drilled in an area northwest of the existing building
within the footprint of the proposed addition. A second test hole (Test Hole 2) was
located in the landscaped area southeast of the existing building in the footprint area of
the proposed deck. Two additional test holes (Test Holes 3 and 4) were drilled for
pavement exploration in existing parking lot and in a proposed parking area to the east.
(See Figure 1.)
Test hole depths were as follows: 50 feet for Test Hole 1, 13½ feet for Test Hole 2, 5½
for Test Hole 3, and 8 feet for Test Hole 4. Test holes were advanced using a
conventional, track-mounted, drilling rig to evaluate the subsurface conditions, as well as
to retrieve soil samples for laboratory testing and analysis.
A GROUND engineer directed the subsurface exploration, logged the test holes in the
field, and prepared the soil samples for transport to our laboratory.
Samples of the subsurface materials were retrieved with a 2-inch I.D. “California” -type
liner sampler and a 1⅜-inch I.D. Standard Penetration Test (“split spoon”) sampler. The
samplers were driven into the substrata with blows from a 140-pound hammer falling 30
inches. This procedure is similar to the Standard Penetration Test described by ASTM
Method D1586. Penetration resistance values, when properly evaluated, indicate the
relative density or consistency of soils. Depths at which the samples were obtained and
associated penetration resistance values are shown on the test hole logs.
The approximate locations of the test holes are shown in Figure 1. Logs of the
exploratory test holes are presented in Figure 2. Explanatory notes and a legend are
provided in Figure 3. To locate the test holes, GROUND utilized the site plan provided
by The Town of Vail indicating existing features.
Proposed Golf Course Clubhouse Additions
1610 Sunburst Drive
Vail, Colorado
Job No. 15-6007R1 Ground Engineering Consultants, Inc. Page 4
LABORATORY TESTING
Samples retrieved from our test holes were examined and visually classified in the
laboratory by the project engineer. Laboratory testing of soil samples obtained from the
subject site included standard property tests, such as natural moisture contents, dry unit
weights, grain size analyses, and liquid and plastic limits. Swell-consolidation, water-
soluble sulfate and corrosivity tests were performed on selected samples of the soils as
well. Laboratory tests were performed in general accordance with applicable ASTM and
AASHTO protocols. Results of the laboratory testing program are summarized on
Tables 1.
SUBSURFACE CONDITIONS
The subsurface conditions encountered in the test hole generally consisted of about 2 to
6 feet of undocumented fill materials over sands and gravels. Loose silty sands were
encountered below approximately 8½ feet in Test Hole 1. Cobbles and possible
boulders were encountered below fill materials in Test Hole’s 2, 3, and 4, and practical
drilling refusal occurred at a depth of 13½, 5½, and 8 feet below surface grade,
respectively. Groundwater was encountered at 8½ feet in Test Hole 2 after drilling, and
at 6½ feet when checked 7 days later. Test hole 1 caved at 7 feet after drilling.
Fill The fill soils encountered consisted of clayey sands and gravels, low plasticity clay,
fine to coarse sand fractions with scattered gravels and cobbles. Fill material was loose
to very dense, moist, and dark brown in color.
Sand and Gravels with Cobbles and possible boulders. The natural soils encountered
were stratified layers of clean sand and sandy gravels with scattered cobbles. Very
dense cobbles and possible boulders were encountered below fill material. Soils
generally consisted of medium to coarse sands, angular to sub-rounded gravels,
medium dense to very dense, moist to wet, and light brown to brown in color.
Sand silty, fine to coarse fractions, scattered gravels, loose, wet, brown in color.
It should be noted that it is not possible to characterize coarse gravel-, cobble- and
boulder-sized materials in small diameter test holes. Therefore, those relying on this
report should anticipate that coarser materials than recognized herein may be present in
the soils at this site.
Proposed Golf Course Clubhouse Additions
1610 Sunburst Drive
Vail, Colorado
Job No. 15-6007R1 Ground Engineering Consultants, Inc. Page 5
Swell-Consolidation Testing suggested a slight potential for consolidation in the sands
and gravels when wetted under various surcharge loads.
A test performed on a sample of silty sand with gravel at Test Hole 4 indicated a
consolidation of 0.4 percent, see Figure 4.
Groundwater was encountered at approximately 8½ feet in Test Hole 2 at the time of
drilling to the depths explored, and at about 6½ feet when checked 7 days later.
Fluctuations in ground water levels may occur and the water table may be significantly
higher during spring and summer seasons.
GEOTECHNICAL CONSIDERATIONS FOR DESIGN
Natural soils below fill are medium dense to very dense sands and gravels with cobbles
and possible boulders present. GROUND recommends spread footings bearing on the
natural granular soils below the fill would be feasible for foundation support of the
addition and deck. We estimate post-construction movement to be less than 1-inch.
Relatively shallow groundwater was observed in the area and dewatering will be
necessary for construction. Based on provided groundwater observation reports, by
others, it appears groundwater levels have risen to as close as 3.3 feet from the ground
surface in June. However, groundwater levels appear to be dropping since June, with
reported levels around 5 to 6 feet in late July.
GROUND is available to meet to discuss the geotechnical risks and remedial
approaches presented in this report, as well as other possible design approaches.
Please contact any of our offices for assistance in that regard.
SHALLOW FOUNDATION SYSTEMS
Considering the subsoil conditions encountered in the exploratory test hole and the
nature of the proposed construction, we recommend the addition be placed on spread
footings bearing on natural granular soils. The design and construction criteria
presented below should be observed for a spread footing foundation system for the
proposed golf course addition and deck support:
1. We recommend spread footings placed on the undisturbed natural granular soil
be designed for an allowable soil bearing pressure (Qa) of 2,500 psf for footings
up to 4 feet in width.
Proposed Golf Course Clubhouse Additions
1610 Sunburst Drive
Vail, Colorado
Job No. 15-6007R1 Ground Engineering Consultants, Inc. Page 6
2. Based on conditions encountered in the test holes, footings likely will bear on
native sands and gravels at depths of 5 to 7 feet.
3. Footings should bear at an elevation 4 or more feet below the lowest adjacent
exterior finish grades to have adequate soil cover above their bearing elevation
for frost protection. Where 4 feet of soil cover cannot be provided, insulation can
often be used to protect footings from frost heave. More detailed information is
available in the Design Guide for Frost-Protected Shallow Foundations.
4. If it is desired for footings to bear at shallower depths, footing grade can be re-
established by excavating existing fill and replacing with properly compacted on-
site soils.
5. Footing excavation bottoms may expose debris, organics, loose or otherwise
unsuitable materials which should be excavated and footing grade lowered or
replaced with properly compacted fill.
6. Spread footings should have a minimum footing lateral dimension of 16 or more
inches for linear strip footings and a minimum lateral dimension of 24 or more
inches for isolated pads. Actual footing dimensions, however, should be
determined by the structural engineer, based on design loads.
7. A 12-inch, or thicker, layer of free draining gravel should be placed at the base of
the addition excavation with an underdrain system to divert water away from
bearing soils.
8. Connections to the structures of all types must be flexible and/or adjustable to
accommodate the potential, post-construction movements.
9. Continuous foundation walls should be reinforced top and bottom to span an
unsupported length of at least 10 feet.
10. The lateral resistance of spread footings will be developed as sliding resistance
of the footing bottoms. Sliding friction at the bottom of footings may be taken as
0.40 times the vertical dead load.
11. The addition should be isolated, structurally, from the existing building. Finishes
that span the joints between the existing building and addition should be tolerant
of differential movement and/or readily replaced.
Proposed Golf Course Clubhouse Additions
1610 Sunburst Drive
Vail, Colorado
Job No. 15-6007R1 Ground Engineering Consultants, Inc. Page 7
12. Compacted fill placed against the sides of the footings should be compacted in
accordance with the recommendations in the Project Earthwork section of this
report.
13. Care should be taken when excavating the foundation to avoid disturbing the
supporting materials.
14. Shallow groundwater should be expected during construction and a de-watering
system may be necessary.
SLAB-ON-GRADE CONCRETE FLOOR
The use of slab-on-grade concrete floors on properly compacted structural fill is feasible
for the project site. The criteria below may be followed where a slab-on-grade floor is
selected.
1. The floor system for the addition should bear on native sands and gravels or a
section of properly compacted on-site soils.
The conditions in the test hole suggest that 5 to 6 feet of existing fill will need to
be removed down to native sands and gravels and replaced with a properly
compacted fill section. The fill section should be taken from the bottom of the
slab + gravel layer system. If the gravel layer is not installed, the fill section
should be correspondingly thickened.
Screened rock (coarser than ¾-inch) may be used as fill material to facilitate
drainage during times of high water table. If screened rock is used, a drainage
system must be installed to divert water away from foundation walls and floor
slabs.
The contractor should take care to construct a fill section of uniform depth and
composition to reduce differential post-construction building, slab and flatwork
movements. A differential fill beneath the building will tend to increase
differential movements.
Organics, or loose, soft or otherwise unsuitable materials exposed on the
prepared surface on which a floor slab will be cast should be excavated and
replaced with properly compacted fill.
Proposed Golf Course Clubhouse Additions
1610 Sunburst Drive
Vail, Colorado
Job No. 15-6007R1 Ground Engineering Consultants, Inc. Page 8
2. Concrete slabs-on-grade should be constructed and cured in accordance with
applicable industry standards and slab design specifications.
3. An allowable vertical modulus of subgrade reaction (Kv) of 54 tcf may be used for
design of concrete slabs bearing on a properly prepared fill section.
4. The floor slabs should be separated from all bearing walls and columns with slip
joints, which allow unrestrained vertical movement.
Joints should be observed periodically by the owner, particularly during the first
several years after construction. Slab movement can cause previously free-
slipping joints to bind. Measures should be taken to assure that slab isolation is
maintained in order to reduce the likelihood of damage to walls and other interior
improvements, including door frames, plumbing fixtures, etc.
5. Interior partitions resting on floor slabs should be provided with slip joints or
tracks so that if the slabs move, the movement cannot be transmitted to the
upper structure. This detail is also important for wallboards and doorframes. Slip
joints, which will allow at least 1½ or more inches of vertical movement, should
be considered.
6. Concrete slab-on-grade floors should be provided with properly designed and
constructed control joints. ACI, AASHTO and other industry groups provide
guidelines for proper design and construction of concrete slabs-on-grade, and
associated jointing. The design and construction of such joints should account
for cracking resulting from concrete shrinkage, curling, tension and applied loads,
as well as other factors related to the proposed slab use. Joint layout based on
slab design may require more frequent, additional or deeper joints than typical
industry minimums, and should reflect the configuration and proposed use of the
slab. Particular attention in slab joint design should be given to areas where
slabs exhibit interior corners or curves, e.g., at column block-outs or reentrant
corners, and slabs with high length to width ratios, significant slopes, thickness
transitions, high traffic loads, or other unique features. The improper placement
or construction of control joints will increase the potential for slab cracking.
7. A floor slab should be adequately reinforced. Recommendations based on
structural considerations for slab thickness, jointing, and steel reinforcement in
floor slabs should be developed by a structural engineer.
Proposed Golf Course Clubhouse Additions
1610 Sunburst Drive
Vail, Colorado
Job No. 15-6007R1 Ground Engineering Consultants, Inc. Page 9
8. Moisture can be introduced into a slab subgrade during construction and
additional moisture will be released from the slab concrete as it cures. GROUND
recommends placement of a properly compacted layer of free-draining gravel, 8
or more inches in thickness, beneath the slabs. This layer will help distribute
floor slab loadings, ease construction, reduce capillary moisture rise, and aid in
drainage. The free-draining gravel should contain less than 5 percent material
passing the No. 200 Sieve, more than 50 percent retained on the No. 4 Sieve,
and a maximum particle size of 2 inches.
The capillary break and the drainage space provided by the gravel layer also
may reduce the potential for excessive water vapor fluxes from the slab after
construction as mix water is released from the concrete.
We understand, however, that professional experience and opinion differ with
regard to inclusion of a free-draining gravel layer beneath slab-on-grade floors. If
these issues are understood by the owner and appropriate measures are
implemented to address potential concerns including slab curling and moisture
fluxes, then the gravel layer may be deleted.
PROJECT EARTHWORK
The project site has undergone previous grading for the existing building construction
and surrounding pedestrian walkways. We anticipate cuts of approximately 4 to 6 feet to
construct the addition, 3 to 4 feet for deck columns or pads, and up to 2 feet for concrete
walkway areas depending on the earthwork selected.
The following information is for private improvements; public roadways or utilities
should be constructed in accordance with applicable municipal / agency
standards.
General Considerations Site grading should be performed as early as possible in the
construction sequence to allow settlement of fills and surcharged ground to be realized
to the greatest extent prior to subsequent construction.
Prior to earthwork construction, vegetation and other deleterious materials should be
removed and disposed of off-site. Relic underground utilities should be abandoned in
accordance with applicable regulations, removed as necessary, and properly capped.
Proposed Golf Course Clubhouse Additions
1610 Sunburst Drive
Vail, Colorado
Job No. 15-6007R1 Ground Engineering Consultants, Inc. Page 10
Topsoil present on-site should not be incorporated into ordinary fills. Instead, topsoil
should be stockpiled during initial grading operations for placement in areas to be
landscaped or for other approved uses.
Existing Fill Soils Actual contents and composition of the fill materials on-site generally
classified as clayey gravelly sand. Some of the excavated fill materials may not be
suitable for replacement as backfill. A geotechnical engineer should be retained during
site excavations to observe the excavated fill materials and provide recommendations
for its suitability for reuse.
Use of Existing Native Soils Native soils that are free of trash, organic material,
construction debris, and other deleterious materials are suitable, in general, for
placement as compacted fill. Organic materials should not be incorporated into project
fills.
Fragments of rock, cobbles, and inert construction debris (e.g., concrete or asphalt)
larger than 3 inches in maximum dimension will require special handling and/or
placement to be incorporated into project fills. In general, such materials should be
placed as deeply as possible in the project fills. A geotechnical engineer should be
consulted regarding appropriate recommendations for usage of such materials on a
case-by-case basis when such materials have been identified during earthwork.
Standard recommendations that likely will be generally applicable can be found in
Section 203 of the current CDOT Standard Specifications for Road and Bridge
Construction.
Imported Fill Materials If it is necessary to import material to any of the sites, the
imported soils should be free of organic material and other deleterious materials.
Imported material for use as common fill should consist of soils that have less than 30
percent passing the No. 200 Sieve and should have a plasticity index of less than 10.
Representative samples of the materials proposed for import should be tested and
approved prior to transport to the site. “Pit run” material for use as common fill should be
approved prior to use.
Fill Platform Preparation Prior to filling, the top 8 to 12 inches of in-place materials on
which fill soils will be placed should be scarified, moisture conditioned and properly
compacted in accordance with the recommendations below to provide a uniform base for
fill placement. Where over-excavation is performed, these measures for subgrade
preparation apply to the subgrade surface at the base of the over-excavation depth.
Proposed Golf Course Clubhouse Additions
1610 Sunburst Drive
Vail, Colorado
Job No. 15-6007R1 Ground Engineering Consultants, Inc. Page 11
If surfaces to receive fill expose loose, wet, soft or otherwise deleterious material,
additional material should be excavated, or other measures taken to establish a firm
platform for filling. The surfaces to receive fill must be effectively stable prior to
placement of fill.
Fill Placement Fill materials should be thoroughly mixed to achieve a uniform moisture
content, placed in uniform lifts not exceeding 8 inches in loose thickness, and properly
compacted.
All soils should be compacted to 95 or more percent of the maximum dry density at
moisture contents within 2 percent of the optimum moisture content as determined by
ASTM D1557, the “modified Proctor.”
No fill materials should be placed, worked, rolled while they are frozen, thawing, or
during poor/inclement weather conditions.
Care should be taken with regard to achieving and maintaining proper fill soil moisture
contents during placement and compaction. Soils with excessive moisture may exhibit
pumping, rutting, and deflection, and not compact effectively. The contractor should be
prepared to handle soils of this type, including using chemical stabilization, where
necessary.
Compaction areas should be kept separate, and no lift should be covered by another
until relative compaction and moisture content within the recommended ranges are
obtained.
Where soils supporting building floors or on which floors will be placed are exposed to
freezing temperatures or repeated freeze – thaw cycling during construction (commonly
due to water ponding on project soils) bearing capacity typically is reduced and/or
settlements increased due to the loss of density in the supporting soils. After periods of
freezing conditions, the contractor should re-work areas affected by the formation of ice
to re-establish adequate bearing support.
Use of Squeegee Relatively uniformly graded fine gravel or coarse sand, i.e.,
“squeegee,” or similar materials commonly are proposed for backfilling foundation
excavations, utility trenches (excluding approved pipe bedding), and other areas where
employing compaction equipment is difficult. In general, GROUND does not recommend
this procedure for the following reasons:
Proposed Golf Course Clubhouse Additions
1610 Sunburst Drive
Vail, Colorado
Job No. 15-6007R1 Ground Engineering Consultants, Inc. Page 12
Although commonly considered “self compacting,” uniformly graded granular materials
require densification after placement, typically by vibration. The equipment to densify
these materials is not available on many job-sites.
Even when properly densified, uniformly graded granular materials are permeable and
allow water to reach and collect in the lower portions of the excavations backfilled with
those materials. This leads to wetting of the underlying soils and resultant potential loss
of bearing support as well as increased local heave or settlement.
GROUND recommends that wherever possible, excavations be backfilled with approved,
on-site soils placed as properly compacted fill. Where this is not feasible, use of
“Controlled Low Strength Material” (CLSM), i.e., a lean, sand-cement slurry (“flowable
fill”) or a similar material for backfilling should be considered.
Where “squeegee” or similar materials are proposed for use by the contractor, the
design team should be notified by means of a Request for Information (RFI), so that the
proposed use can be considered on a case-by-case basis. Where “squeegee” meets
the project requirements for pipe bedding material, however, it is acceptable for that use.
Settlements will occur in filled ground, typically on the order of 1 to 2 percent of the fill
depth. If fill placement is performed properly and is tightly controlled, in GROUND’s
experience the majority (on the order of 60 to 80 percent) of that settlement will typically
take place during earthwork construction, provided the contractor achieves the
compaction levels recommended herein. The remaining potential settlements likely will
take several months or longer to be realized, and may be exacerbated if these fills are
subjected to changes in moisture content.
Cut and Filled Slopes Permanent site slopes supported by on-site soils up to 4 feet in
height may be constructed no steeper than 2½:1 (horizontal : vertical). Minor raveling or
surficial sloughing should be anticipated on slopes cut at this angle until vegetation is
well re-established. Surface drainage should be designed to direct water away from
slope faces.
EXCAVATION CONSIDERATIONS
The test holes for the subsurface exploration were excavated to the depths indicated by
means of truck-mounted, flight auger drilling equipment. We anticipate no significant
excavation difficulties in the majority of the site with conventional heavy-duty excavation
equipment in good working condition. However, equipment mobility will likely be
Proposed Golf Course Clubhouse Additions
1610 Sunburst Drive
Vail, Colorado
Job No. 15-6007R1 Ground Engineering Consultants, Inc. Page 13
problematic within close proximity to the groundwater table. Soil stabilization may be
necessary for constructability considerations.
We recommend that temporary, un-shored excavation slopes up to 8 feet in height be
cut no steeper than 1½:1 (horizontal : vertical) in the site soils in the absence of
seepage. Sloughing on the slope faces should be anticipated at this angle. Local
conditions encountered during construction, such as groundwater seepage and loose
sand, will require flatter slopes. Stockpiling of materials should not be permitted closer
to the tops of temporary slopes than 5 feet or a distance equal to the depth of the
excavation, whichever is greater.
Should site constraints prohibit the use of the recommended slope angles, temporary
shoring should be used. The shoring should be designed to resist the lateral earth
pressure exerted by building, traffic, equipment, and stockpiles. GROUND can provide
shoring design upon request.
Good surface drainage should be provided around temporary excavation slopes to direct
surface runoff away from the slope faces. A properly designed drainage swale should
be provided at the top of the excavations. In no case should water be allowed to pond at
the site. Slopes should also be protected against erosion. Erosion along the slopes will
result in sloughing and could lead to a slope failure.
Excavations in which personnel will be working must comply with all OSHA Standards
and Regulations. The contractor’s “responsible person” should evaluate the soil
exposed in the excavations as part of the contractor’s safety procedures. GROUND has
provided the information above solely as a service to The Town of Vail, and is not
assuming responsibility for construction site safety or the Contractor’s activities.
LATERAL EARTH PRESSURES
The following lateral earth pressures may be used for the design of foundation walls and
evaluation of resistance to lateral loads. If select, granular imported soil is used as wall
backfill, it should meet the parameters for CDOT Class 1 Structure Backfill.
Proposed Golf Course Clubhouse Additions
1610 Sunburst Drive
Vail, Colorado
Job No. 15-6007R1 Ground Engineering Consultants, Inc. Page 14
EQUIVALENT FLUID PRESSURES (DRAINED CONDITION)
Backfill
Material
Condition
Friction
Coefficient
Active
At-Rest
Passive
On-Site Soil 43 pcf 65 pcf 390 pcf 0.40
Select Granular
Fill 35 pcf 55 pcf 442 pcf 0.45
EQUIVALENT FLUID PRESSURES (SUBMERGED CONDITION)
Backfill
Material
Condition
Friction
Coefficient
Active
At-Rest
Passive
On-Site Soil 85 pcf 96 pcf 265 pcf 0.40
Select Granular
Fill 80 pcf 90 pcf 283 pcf 0.45
The earth pressures tabulated above assume a horizontal backfill surface.
To use the values for CDOT Class 1 Structure Backfill, that material must extend
at full depth from the back of the wall to a distance behind the wall at least equal
to half of the wall height.
Wall design should incorporate any upward sloping backfills, live loads such as
construction equipment, material stockpiles, etc., and other surcharge pressures.
Backfill soils should be thoroughly mixed to achieve a uniform moisture content, placed
in uniform lifts not exceeding 6 inches in loose thickness, and properly compacted in
accordance with the recommendations in the Site Grading section of this report. The
contractor should take care not to over-compact the backfills, which could result in
excessive lateral pressures on the walls.
Some settlement of wall backfills will occur even where the material was placed
correctly. This settlement likely will be differential, increasing with depth of fill. Where
shallowly founded structures and pavements must be placed on backfilled zones,
structural design, pipe connections, etc., should take into account backfill settlement,
including differential movement. Considerations should be given to new and existing fill
settlements where improvements are founded in such areas.
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WATER-SOLUBLE SULFATES
The concentrations of water-soluble sulfates measured in selected sample retrieved
from the test holes was less than approximately 0.03 percent by weight. (See Table 1.)
Such concentrations of water-soluble sulfates represent a negligible degree of sulfate
attack on concrete exposed to these materials. Degrees of attack are based on the
scale of 'negligible,' 'moderate,' 'severe' and 'very severe' as described in the “Design
and Control of Concrete Mixtures,” published by the Portland Cement Association
(PCA).
Based on these data GROUND, makes no recommendation for use of a special, sulfate-
resistant cement in project concrete.
SOIL CORROSIVITY
The degree of risk for corrosion of metals in soils commonly is considered to be in two
categories: corrosion in undisturbed soils and corrosion in disturbed soils. The potential
for corrosion in undisturbed soil is generally low, regardless of soil types and conditions,
because it is limited by the amount of oxygen that is available to create an electrolytic
cell. In disturbed soils, the potential for corrosion typically is higher, but is strongly
affected by soil conditions for a variety of reasons but primarily soil chemistry.
A corrosivity analysis was performed in upper fill material at the proposed clubhouse
addition to provide a general assessment of the potential for corrosion of ferrous metals
installed in contact with earth materials at the site, based on the conditions existing at
the time of GROUND’s evaluation. Soil chemistry and physical property data including
pH, oxidation-reduction (redox) potential, sulfides, and moisture content were obtained.
Test results are summarized on Table 1.
Reduction-Oxidation Reduction and oxidation testing indicated negative potential: -29
millivolts. Such a low potentials typically creates a more corrosive environment.
Sulfide Reactivity Sulfide reactivity testing for the presence of sulfides indicated a
“positive” result in the on-site soils. The presence of sulfides suggests a more corrosive
environment.
pH Where pH is less than 4.0, soil serves as an electrolyte; the pH range of about 6.5 to
7.5 indicates soil conditions that are optimum for sulfate reduction. In the pH range
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above 8.5, soils are generally high in dissolved salts, yielding a low soil resistivity1.
Testing indicated a pH value of approximately 7.5 in the local earth materials.
Soil Resistivity In order to assess the “worst case” for mitigation planning, samples of
materials retrieved from the test holes were tested for resistivity in the laboratory, after
being saturated with water, rather than in the field. Resistivity also varies inversely with
temperature. Therefore, the laboratory measurements were made at a controlled
temperature. Measurements of electrical resistivity indicated a value of approximately
4,767 ohm-centimeters in a sample of the site earth materials.
The American Water Works Association (AWWA) has developed a point system scale
used to predict corrosivity. The scale is intended for protection of ductile iron pipe but is
valuable for project steel selection. When the scale equals 10 points or higher,
protective measures for ductile iron pipe are recommended. The AWWA scale is
presented below. The soil characteristics refer to the conditions at and above pipe
installation depth.
TABLE A.1 SOIL-TEST EVALUATION 2
Soil Characteristic / Value Points
Resistivity
<1,500 ohm-cm ................................................................................................. 10
1,500 to 1,800 ohm-cm ....................................................................................... 8
1,800 to 2,100 ohm-cm ....................................................................................... 5
2,100 to 2,500 ohm-cm ....................................................................................... 2
2,500 to 3,000 ohm-cm ....................................................................................... 1
>3,000 ohm-cm ........................................................................................ 0
pH
0 to 2.0 ........................................................................................................... 5
2.0 to 4.0 ......................................................................................................... 3
4.0 to 6.5 ......................................................................................................... 0
6.5 to 7.5 ...................................................................................................... 0 *
7.5 to 8.5 ......................................................................................................... 0
>8.5 .......................................................................................................... 3
Redox Potential
< 0 (negative values) . ...................................................................................... 5
0 to +50 mV ..................................................................................................... 4
+50 to +100 mV .................................................................................… ....... 3½
> +100 mV . .............................................................................................. 0
Sulfide Content
Positive .... ..................................................................................................... 3½
1,3 American Water Works Association ANSI/AWWA C105/A21.5-05 Standard
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Trace ...........… .................................................................................................. 2
Negative .......…. ................................................................................................ 0
Moisture
Poor drainage, continuously wet......................................…. ............................ 2
Fair drainage, generally moist ......................… ............................................. 1
Good drainage, generally dry ......................................... .............................. 0
* If sulfides are present and low or negative redox-potential results (< 50 mV)
are obtained, add three points for this range.
We anticipate that drainage at the site after construction will be good. Even with
effective drainage, based on the values obtained for the soil parameters (11½ points),
the site soils appear to comprise a high risk environment for metals with regard to
corrosion.
Corrosive conditions can be addressed by use of materials not vulnerable to corrosion,
heavier gauge materials with longer design lives, polyethylene encasement, or cathodic
protection systems. If additional information or recommendations are needed regarding
soil corrosivity, GROUND recommends contacting the American Water Works
Association or a Corrosion Engineer. It should be noted, however, that changes to the
site conditions during construction, such as the import of other soils, or the intended or
unintended introduction of off-site water, may alter corrosion potentials significantly.
SURFACE DRAINAGE
The following drainage measures are recommended for design, construction, and should
be maintained at all times after the project has been completed:
1) Wetting or drying of foundation and underslab areas should be avoided.
Permitting increases/variations in moisture to the adjacent or supporting soils
may result in a decrease in bearing capacity and an increase in volume change
of the underlying soils and/or differential movement.
2) Positive surface drainage measures should be provided and maintained to
reduce water infiltration into foundation soils. The ground surface surrounding
the exterior of the building should be sloped to drain away from the foundation in
all directions. We recommend a minimum slope of 12 inches in the first 10 feet in
areas not covered with pavement or concrete slabs, or a minimum 3 percent in
the first 10 feet in the areas covered with pavement or concrete slabs. Reducing
the slopes to comply with ADA requirements may be necessary but may result in
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Vail, Colorado
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an increased potential for moisture infiltration and subsequent volume change of
the underlying soils. In no case should water be allowed to pond near or
adjacent to foundation elements. However, if positive surface drainage is
implemented and maintained directing moisture away from the building, lesser
slopes can be utilized if the risk of incrementally greater settlements is accepted.
In no case should water be allowed to pond near or adjacent to foundation
elements, or on sidewalks, hardscaping, or other improvements as well as utility
trench alignments, which are likely to be adversely affected by moisture-volume
changes in the underlying soils or flow of infiltrating water.
Drainage measures also should be included in project design to direct water
away from sidewalks and other hardscaping as well as utility trench alignments
which are likely to be adversely affected by moisture-volume changes in the
underlying soils or flow of infiltrating water. Routine maintenance of site drainage
should be undertaken throughout the design life of the project.
In GROUND’s experience, it is common during construction that in areas of
partially completed paving or hardscaping, bare soil behind curbs and gutters,
and utility trenches, water is allowed to pond after rain or snow-melt events.
Wetting of the subgrade can result in loss of subgrade support and increased
settlements / increase heave. By the time final grading has been completed,
significant volumes of water can already have entered the subgrade, leading to
subsequent distress and failures. The contractor should maintain effective site
drainage throughout construction so that water is directed into appropriate
drainage structures.
3) Roof downspouts and drains should discharge well beyond the perimeter of the
structure’s foundation, or be provided with positive conveyance off-site for
collected waters. Downspouts should not discharge into a building underdrain
system.
4) Landscaping which requires watering should be located 10 or more feet from the
building perimeter. Irrigation sprinkler heads should be deployed so that applied
water is not introduced into foundation soils. Landscape irrigation should be
limited to the minimum quantities necessary to sustain healthy plant growth.
Use of drip irrigation systems can be beneficial for reducing over-spray beyond
planters. Drip irrigation also can be beneficial for reducing the amounts of water
Proposed Golf Course Clubhouse Additions
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Vail, Colorado
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introduced to building foundation soils, but only if the total volumes of applied
water are controlled with regard to limiting that introduction. Controlling rates of
moisture increase beneath the foundations and floors should take higher priority
than minimizing landscape plant losses.
Where plantings are desired within 10 feet of the building, GROUND
recommends that the plants be placed in water-tight planters, constructed either
in-ground or above-grade, to reduce moisture infiltration in the surrounding
subgrade soils. Planters should be provided with positive drainage and
landscape underdrains.
5) We do not recommend the use of plastic membranes to cover the ground surface
near the building without careful consideration of other components of project
drainage. Plastic membranes can be beneficial to directing surface waters away
from the building and toward drainage structures. However, they effectively
preclude evaporation or transpiration of shallow soil moisture. Therefore, soil
moisture tends to increase beneath a continuous membrane. Where plastic
membranes are used, additional shallow, subsurface drains should be installed.
SUBSURFACE DRAINAGE
As a component of project civil design, properly functioning, subsurface drain systems
(underdrains, foundation or perimeter drains) can be beneficial for collecting and
discharging saturated subsurface waters. Underdrains will not collect water infiltrating
under unsaturated (vadose) conditions, or moving via capillarity, however. In addition, if
not properly constructed and maintained, underdrains can transfer water into foundation
soils, rather than remove it. This will tend to induce heave or settlement of the
subsurface soils, and may result in distress. Underdrains can, however, provide an
added level of protection against relatively severe post-construction movements by
draining saturated conditions near individual structures should they arise, and limiting
the volume of wetted soil.
Where below-grade spaces are present, the foundation wall and slab should be provided
with an underdrain system, with the exception of the elevator sump. Given the potential
for large volumes of water to enter the elevator sump area, we suggest designing and
constructing the elevator sump area to be water-tight. Damp-proofing should be applied
to the exteriors of below-grade elements. The provision of Tencate MiraFi® G-Series
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backing (or comparable wall drain provisions) on the exteriors of (some) below-grade
elements may be appropriate, depending on the intended use.
Geotechnical Parameters for Underdrain Design Where an underdrain system is
included in project drainage design, it should be designed in accordance with the
recommendations below. The actual underdrain layout, outlets, and locations should be
developed by a civil engineer. A conceptual underdrain detail is depicted in Figure 5.
An underdrain system should be tested by the contractor after installation and after
placement and compaction of the overlying backfill to verify that the system functions
properly.
1) The underdrain trench should be located outside of a 1(H) : 1(V) slope from the
bottom of the footing to avoid undermining soil supporting the footings.
2) An underdrain system for the improvements should consist of perforated, rigid,
PVC collection pipe at least 4 inches in diameter, non-perforated, rigid, PVC
discharge pipe at least 4 inches in diameter, free-draining gravel, and filter fabric,
as well as a waterproof membrane. Drain diameter should ultimately be sized
based on the anticipated flow volume.
3) The free-draining gravel should contain less than 5 percent passing the No. 200
Sieve and more than 50 percent retained on the No. 4 Sieve, and have a
maximum particle size of 2 inches. Each collection pipe should be surrounded
on the sides and top (only) with 6 or more inches of free-draining gravel.
4) The gravel surrounding the collection pipe(s) should be wrapped with filter fabric
(MiraFi 140N® or the equivalent) to reduce the migration of fines into the drain
system.
5) An underslab gravel drainage layer at least 12 inches in thickness is suggested
for below grade slab areas. The slab gravel drainage layer should be
hydraulically connected to the underdrain through blockouts in the foundation
wall at 30 feet on-center maximum.
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6) The high point(s) for the underdrain collection pipe flow lines should be at least 6
inches below the bottom of slab gravel layer. Multiple high points are sometimes
necessary for significant building perimeter lengths.
The collection and discharge pipe for the underdrain system should be laid on a
slope sufficient for effective drainage, but a minimum of 1 percent. (Flatter
gradients have been used but will convey water less efficiently and entail an
increased risk of local post-construction movements.)
Pipe gradients also should be designed to accommodate at least ½ inch of
differential movement after installation along a 40-foot run.
7) Underdrain ‘clean-outs’ should be provided at intervals of no more than 100 feet
to facilitate maintenance of the underdrains. Clean-outs also should be provided
at collection and discharge pipe elbows of 60 degrees or more.
8) The underdrain discharge pipes should be connected to one or more sumps from
which water can be removed by pumping, or to outlet(s) for gravity discharge.
We suggest that collected waters be discharged directly into the storm sewer
system, if possible.
Underdrain Discharge Volumes
At the request of the project team, an evaluation of potential inflow rates to the
underdrain system was performed. Hydraulic conductivity was estimated for the site
soils based on grain size distribution using the Hazen (1911) and Shepard (1989)
methods. The estimated hydraulic conductivities are presented on the following table.
Soil Type
Hydraulic
Conductivity
(cm/s)
Hydraulic
Conductivity
(gal/day/ft2)
On-Site Sand and
Gravel 1.2 25,440
On-Site Fill Soils 0.012 254
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Inflow volumes were estimated for each soil type for the maximum anticipated
groundwater elevation corresponding to the 100 year storm event high water elevation of
31 feet with an average perimeter drain elevation of 27.5 feet (3.5 feet of head), as well
as a seasonal high groundwater elevation of 29 feet (1.5 feet of head), and a drain
perimeter of 60 feet. The inflow volumes were estimated for steady state seepage
conditions, and initial discharge volumes should be anticipated to be higher until steady
state conditions are achieved.
Soil Type 3.5 feet of head 1.5 feet of head
On-Site Sand and Gravel 370 gpm 110 gpm
On-Site Fill Soils 4 gpm 1 gpm
The results indicate the amount of inflow will be highly dependent on the depth of fill
soils and soil type enclosing the perimeter drain. The available subsurface data
indicates fill depths are on the order of 3.5 feet or more below grades, and therefore we
estimate actual inflow volumes will likely lie somewhere between the two estimates.
Again, these volumes are for 60 linear feet of perimeter drain and flow volumes can be
roughly interpolated for longer perimeter drain lengths.
Based on the currently proposed amount of underdrain, inflow volumes may quickly
become unpractical to manage. An alternative to the underdrain could include the
design and construction of a “water tight” elevator pit with a sump as a backup to remove
any water accumulation that makes its way through the “water tight” system. Buoyancy
forces and lateral earth pressures including hydrostatic pressure should be considered
for such a scenario. The Lateral Earth Pressure section has been updated to provide
submerged lateral earth pressure values.
GOLF COURSE PARKING LOT
A pavement section is a layered system designed to distribute concentrated traffic loads
to the subgrade. Performance of the pavement structure is directly related to the
physical properties of the subgrade soils and traffic loadings. The Town of Vail
specifications may govern construction parameters at the site, however, GROUND
recommends pavement sections developed in general accordance with the guidelines
and procedures of the American Association of State Highway and Transportation
Officials (AASHTO), the Colorado Department of Transportation (CDOT) and local
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Vail, Colorado
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construction practice. We understand design is preliminary for the existing and
proposed parking area, which may include an overlay to existing asphalt or the removal
and replacement of existing pavement.
Subgrade Materials Based on the results of our field and laboratory studies, the
subgrade soils in the existing and proposed parking areas consisted predominantly of
non-plastic sands and gravels. These materials were classified typically as A-1-A to A-4
soils in accordance with the AASHTO classification system, with Group Index values
from 0 to 1.
Anticipated Traffic An equivalent 18-kip daily load application (EDLA) value of 3 was
assumed for automobile-only parking stalls. An EDLA of 6 was assumed for the parking
area drive aisles. The EDLA values of 3 and 6 were converted to equivalent 18-kip
single-axle load (ESAL) values of 21,900 and 43,800, respectively, for 20-year design
lives. An EDLA of 50, corresponding to an ESAL value of 365,000, was assumed for
areas subject to heavier traffic. We understand that bus traffic will be limited to
roadways west of the parking areas.
If design traffic loadings differ significantly from these assumed values, GROUND should
be notified to re-evaluate the pavement recommendations below.
Pavement Sections The anticipated ESAL values were used to determine the required
structural number for the project pavements. The required structural number was then
used to develop recommended, minimum, pavement sections. Pavement sections were
based on the DARWin™ computer program that solves the 1993 AASHTO pavement
design equation. Pavement parameters and calculations are summarized in Appendix
A. A Reliability Level of 75 percent was utilized develop the pavement sections.
Structural coefficients of 0.40 and 0.12 were used for hot bituminous asphalt and high
quality aggregate base course, respectively.
The resultant minimum pavement sections, based on assumed traffic, recommended by
GROUND are tabulated below. Alternatively, the Town of Vail minimum pavement
sections may be used provided actual traffic volumes do not exceed the assumed traffic
volumes the following pavement sections are based on.
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RECOMMENDED MINIMUM PAVEMENT SECTIONS
Location Section
Parking Lot Aisles 4 inches Asphalt / 7 inches Aggregate Base
Parking Stalls 4 inches Asphalt / 6 inches Aggregate Base
Heavy Vehicle Traffic 6½ inches of pcc / 6 inches of aggregate base
We recommend that any portions of the parking lot intended for heavy vehicle traffic be
provided with rigid pavements consisting of 6½ or more inches of Portland cement
concrete. For superior performance, the concrete should be underlain by 6 or more
inches of properly compacted CDOT Class 6 Aggregate Base Course. A numerically
equivalent composite section would be 5½ inches of asphalt over 11 inches of aggregate
base, but that section would not perform as well as a rigid section under heavy vehicle
traffic and turning stresses.
Aggregate base thickness may be reduced if geosynthetic reinforcement is incorporated
into the base section. Base course thickness may be reduced by 30 percent, to a
minimum of 4 inches, if RS380i or approved equivalent is incorporated into the base
section. Geosynthetics, if used, should be placed at the bottom of the base section and
extend at least 3 feet beyond the edges of the pavement.
Pavement Materials Asphalt pavement should consist of a bituminous plant mix
composed of a mixture of aggregate and bituminous material. Asphalt mixture(s) should
meet the requirements of a job-mix formula established by a qualified engineer as well
as applicable municipal design requirements.
Concrete pavements should consist of a plant mix composed of a mixture of aggregate,
portland cement and appropriate admixtures meeting the requirements of a job-mix
formula established by a qualified engineer as well as applicable municipal design
requirements. Concrete should have a minimum modulus of rupture of third point
loading of 650 psi. Normally, concrete with a 28-day compressive strength of 4,200 psi
should develop this modulus of rupture value. The concrete should be air-entrained with
approximately 6 percent air and should have a minimum cement content of 7 sacks per
cubic yard. Maximum allowable slump should be 4 inches.
Concrete pavements should contain sawed or formed joints. CDOT and various industry
groups provide guidelines for proper design and concrete construction and associated
jointing. In areas of repeated turning stresses we recommend that the concrete
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pavement joints be fully tied and doweled. We suggest that civil design consider joint
layout in accordance with CDOT’s M standards, found at the CDOT website:
http://www.dot.state.co.us/DesignSupport/.
These concrete mix design criteria should be coordinated with other project
requirements including the criteria for sulfate resistance presented in the Water-Soluble
Sulfates section of this report. To reduce surficial spalling resulting from freeze-thaw
cycling, we suggest that pavement concrete meet the requirements of CDOT Class P
concrete. In addition, the use of de-icing salts on concrete pavements during the first
winter after construction will increase the likelihood of the development of scaling.
Placement of flatwork concrete during cold weather so that it is exposed to freeze-thaw
cycling before it is fully cured also increases its vulnerability to scaling. Concrete placing
during cold weather conditions should be blanketed or tented to allow full curing.
Depending on the weather conditions, this may result in 3 to 4 weeks of curing, and
possibly more.
The aggregate base material should meet the criteria of CDOT Class 6 aggregate base
course. The use of recycled concrete for aggregate base is feasible from a geotechnical
perspective; however, the use of base course should also be evaluated for
environmental concerns by others. Aggregate base may also contain recycled asphalt
millings; however, recycled asphalt content should be limited to a maximum of 20
percent in aggregate base. Base course should be placed and compacted as
recommended in the Project Earthwork section of this report.
Subgrade Preparation Although subgrade preparation to a depth of 8 to 12 inches is
typical in the project area, pavement performance and subgrade strength commonly can
be improved by a greater depth of moisture-density conditioning of the soils.
Remedial Earthwork GROUND recommends that shortly before paving, in areas where
subgrade preparation to a depth of 8 to 12 inches still results in unacceptable deflections
as identified by proof rolling, all old fill and soft/loose materials be removed and the
pavement subgrade be excavated and replaced to a depth of at least 2 feet, moisture-
conditioned and properly re-compacted or stabilized. Recommendations for fill
placement and compaction are provided in the Project Earthwork section of this report.
The contractor should be prepared either to dry the subgrade materials or moisten them,
as needed, prior to compaction.
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Subgrade preparation should extend the full width of the pavement from back-of-curb to
back-of-curb. The subgrade for sidewalks and other project hardscaping also should be
prepared in the same manner.
Proof Rolling Prior to paving and the placement of aggregate base, the subgrade should
be proof rolled with a heavily loaded, pneumatic tired vehicle. Areas that show
excessive deflection during proof rolling should be excavated and replaced and
stabilized. Areas allowed to pond prior to paving will require significant re-working prior
to proof-rolling. Passing proof-rolling is an additional requirement for pavement
subgrade soils; it may be possible for soils to be compacted within the limits indicated in
the Project Earthwork section of this report and fail proof rolling, particularly in the upper
range of recommended moisture contents.
Subgrade Stabilization Because of the silty nature of some of the site soils, they may
“pump” or deflect during compaction and proof-rolling if moisture levels are not carefully
controlled and achieving a stable platform for paving may be difficult. Removal and
replacement, chemical stabilization of the pavement subgrade using lime, fly ash, or
Portland cement, or mechanical stabilization using geosynthetics may be necessary.
It is not possible to assess subgrade stability reliably on the basis of information during
geotechnical exploration or subsequent laboratory testing. It is often our experience that
where an existing pavement is removed, the underlying subgrade exhibits instability
when subjected to construction and/or traffic loading, even where testing suggests
otherwise acceptable moisture contents and density. Therefore, it may be necessary to
stabilize the majority of the existing subgrade prior to repaving. This may require
reprocessing or chemical stabilization of existing soils or removal and replacement with
other site materials or imported soil. Our office should be retained to observe the
subgrade condition and stability during the removal process. If additional or more
specific information is required, then we suggest additional exploration be performed
along the proposed roadway.
Drainage and Maintenance The collection and diversion of surface drainage away
from paved areas is extremely important to satisfactory performance of the pavement.
The subsurface and surface drainage systems should be carefully designed to ensure
removal of the water from paved areas and subgrade soils. Where topography, site
constraints or other factors limit or preclude adequate surface drainage, pavements
should be provided with edge drains to reduce loss of subgrade support. The long-term
performance of the pavement also can be improved greatly by proper backfilling and
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compaction behind curb, gutter, and sidewalk. Unless the interceptor drain and edge
drains (where included) are installed properly and maintained, and site drainage in
general is well maintained, there is an increased risk of poor pavement performance at
this site due to the expansive subgrade materials and the local introduction of off-site
irrigation water.
Landscape irrigation in planters adjacent to pavements and in “island” planters within
paved areas should be carefully controlled or differential settlement and/or rutting of the
nearby pavements will result. Drip irrigation systems are recommended for such
planters to reduce over-spray and water infiltration beyond the planters. Enclosing the
soil in the planters with plastic liners and providing them with positive drainage also will
reduce differential moisture increases in the surrounding subgrade soils. In our
experience, infiltration from planters adjacent to pavements is a principal source of
moisture increase beneath those pavements. This wetting of the subgrade soils from
infiltrating irrigation commonly leads to loss of subgrade support for the pavement with
resultant accelerating distress, loss of pavement life and increased maintenance costs.
This is particularly the case in the later stages of project construction after landscaping
has been emplaced but heavy construction traffic has not ended. Heavy vehicle traffic
over wetted subgrade commonly results in rutting and pushing of flexible pavements,
and cracking of rigid pavements. In relatively flat areas where design drainage gradients
necessarily are small, subgrade settlement can obstruct proper drainage and yield
increased infiltration, exaggerated distress, etc. (These considerations apply to project
flatwork, as well.)
Also, GROUND’s experience indicates that longitudinal cracking is common in asphalt-
pavements generally parallel to the interface between the asphalt and concrete
structures such as curbs, gutters or drain pans. This of this type is likely to occur even
where the subgrade has been prepared properly and the asphalt has been compacted
properly.
The anticipated traffic loading does not include excess loading conditions imposed by
heavy construction vehicles. Consequently, heavily loaded concrete, lumber, and
building material trucks can have a detrimental effect on the pavement. In areas where
the maintenance traffic is turning, concrete pavement is recommended.
As noted above, the standard care of practice in pavement design describes the
recommended flexible pavement section as a “20-year” design pavement; however,
most pavements will not remain in satisfactory condition without regular maintenance
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and rehabilitation procedures performed throughout the life of the pavement.
Maintenance and rehabilitation measures preserve, rather than improve, the structural
capacity of the pavement structure. Therefore, GROUND recommends that an effective
program of regular maintenance be developed and implemented to seal cracks, repair
distressed areas, and perform thin overlays throughout the lives of the pavements. The
greatest benefit of pavement overlaying will be achieved by overlaying sound pavements
that exhibit little or no distress.
Crack sealing should be performed at least annually and a fog seal/chip seal program
should be performed on the pavements every 3 to 4 years. After approximately 8 to 10
years after construction, patching, additional crack sealing, and asphalt overlay may be
required. Prior to overlays, it is important that all cracks be sealed with a flexible,
rubberized crack sealant in order to reduce the potential for propagation of the crack
through the overlay. If actual traffic loadings exceed the values used for development of
the pavement sections, however, pavement maintenance measures will be needed on
an accelerated schedule.
Where parking or driveway areas, or the fire access lane are provided with an aggregate
wearing course (full depth aggregate section), it must be understood that such surfaces
also require routine maintenance to perform as intended. They must be re-graded, and
material added as necessary to remove ruts and allow effective drainage. Where
allowed to pond water, the subgrade will become wetted, providing less support for the
wearing course. Maintenance should be scheduled regularly and after major rainfall or
snowmelt events.
EXTERIOR FLATWORK
Proper design, drainage, construction and maintenance of the areas surrounding the
proposed building and parking/driveway areas are critical to the satisfactory performance
of the project. Sidewalks, entranceway slabs and roofs, fountains, raised planters and
other highly visible improvements commonly are installed within these zones, and
distress in or near these improvements is common. Often, soil preparation in these
areas receives little attention because they fall between the building and pavement
(which are typically built with heavy equipment). Subsequent landscaping and
hardscape installation often is performed by multiple sub-contractors with light or hand
equipment, and over-excavation / soil processing is not performed. Therefore,
GROUND recommends that the design team, contractor, and pertinent subcontractors
Proposed Golf Course Clubhouse Additions
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take particular care with regard to proper subgrade preparation around the structure
exteriors.
Similar to slab-on-grade floors, exterior flatwork and other hardscaping placed on the
soils encountered on-site may experience post-construction movements due to volume
change of the subsurface soils and the relatively light loads that they impose. Both
vertical and lateral soil movements can be anticipated as the soils experience volume
change as the moisture content varies. Distress to rigid hardscaping likely will result.
The following measures will help to reduce damages to these improvements:
1. Subgrade soils beneath project sidewalks, paved entryways and patios, masonry
planters and short, decorative walls, and other hardscaping should be placed on
native sand and gravel or properly compacted fill. We anticipate that 2 to 3 feet
of existing fill will need to be removed and replaced in most areas. To perform
like a slab-on-grade floor, hardscaping should bear on a similar fill section as
those discussed in the Slab on Grade Concrete Floor section.
Excavating to native gravels may not be feasible in all areas. Provided the owner
understands the risks identified above, the subgrade under exterior flatwork or
other (non-building) site improvements should be underlain by a section of
properly compacted fill at least 24 inches in thickness. This should occur prior to
placing any additional fill required to achieve finished design grades. We
estimate potential settlements on the order of 1 to 2 inches with this processing
depth.
2. Prior to placement of flatwork, a proof roll should be performed to identify areas
that exhibit instability and deflection. The soils in these areas should be removed
and replaced with properly compacted fill or stabilized.
3. Flatwork should be provided with effective control joints. Increasing the frequency
of joints may improve performance. ACI recommendations should be followed
regarding construction and/or control joints.
4. In no case should exterior flatwork extend to under any portion of the building
where there is less than two inches of clearance between the flatwork and any
element of the building. Exterior flatwork in contact with brick, rock facades, or
any other element of the building can cause damage to the structure if the
flatwork experiences movements.
Proposed Golf Course Clubhouse Additions
1610 Sunburst Drive
Vail, Colorado
Job No. 15-6007R1 Ground Engineering Consultants, Inc. Page 30
5. As discussed in the Surface Drainage section of this report, proper drainage also
should be maintained after completion of the project, and re-established as
necessary. In no case should water be allowed to pond on or near any of the site
improvements or a reduction in performance should be anticipated.
Concrete Scaling Climatic conditions in the project area including relatively low
humidity, large temperature changes and repeated freeze – thaw cycles, make it likely
that project sidewalks and other exterior concrete will experience surficial scaling or
spalling. The likelihood of concrete scaling can be increased by poor workmanship
during construction, such as ‘over-finishing’ the surfaces. In addition, the use of de-icing
salts on exterior concrete flatwork, particularly during the first winter after construction,
will increase the likelihood of scaling. Even use of de-icing salts on nearby roadways,
from where vehicle traffic can transfer them to newly placed concrete, can be sufficient
to induce scaling. Typical quality control / quality assurance tests that are performed
during construction for concrete strength, air content, etc., do not provide information
with regard to the properties and conditions that give rise to scaling.
We understand that some municipalities require removal and replacement of concrete
that exhibits scaling, even if the material was within specification and placed correctly.
The contractor should be aware of the local requirements and be prepared to take
measures to reduce the potential for scaling and/or replace concrete that scales.
In GROUND’s experience the measures below can be beneficial for reducing the
likelihood of concrete scaling. It must be understood, however, that because of the other
factors involved, including weather conditions and workmanship, surface damage to
concrete can develop, even where all of these measures were followed.
1) Maintaining a maximum water/cement ratio of 0.45 by weight for exterior
concrete mixes.
2) Include Type F fly ash in exterior concrete mixes as 20 percent of the
cementitious material.
3) Specify a minimum, 28-day, compressive strength of 4,500 psi for all exterior
concrete.
4) Include ‘fibermesh’ in the concrete mix also may be beneficial for reducing
surficial scaling.
Proposed Golf Course Clubhouse Additions
1610 Sunburst Drive
Vail, Colorado
Job No. 15-6007R1 Ground Engineering Consultants, Inc. Page 31
5) Cure the concrete effectively at uniform temperature and humidity. This
commonly will require fogging, blanketing and/or tenting, depending on the
weather conditions. As long as 3 to 4 weeks of curing may be required, and
possibly more.
6) Avoid placement of concrete during cold weather so that it is not exposed to
freeze-thaw cycling before it is fully cured.
7) Avoid the use of de-icing salts on given reaches of flatwork through the first
winter after construction.
We understand that commonly it may not be practical to implement some of these
measures for reducing scaling due to safety considerations, project scheduling, etc. In
such cases, additional costs for flatwork maintenance or reconstruction should be
incorporated into project budgets.
CLOSURE
Geotechnical Review The author of this report should be retained to review project
plans and specifications to evaluate whether they comply with the intent of the
recommendations in this report. The review should be requested in writing.
The geotechnical recommendations presented in this report are contingent upon
observation and testing of project earthworks by representatives of GROUND. If another
geotechnical consultant is selected to provide materials testing, then that consultant
must assume all responsibility for the geotechnical aspects of the project by concurring
in writing with the recommendations in this report, or by providing alternative
recommendations.
Materials Testing The Town of Vail should consider retaining a geotechnical engineer
to perform materials testing during construction. The performance of such testing or lack
thereof, in no way alleviates the burden of the contractor or subcontractor from
constructing in a manner that conforms to applicable project documents and industry
standards. The contractor or pertinent subcontractor is ultimately responsible for
managing the quality of their work; furthermore, testing by the geotechnical engineer
does not preclude the contractor from obtaining or providing whatever services they
deem necessary to complete the project in accordance with applicable documents.
Proposed Golf Course Clubhouse Additions
1610 Sunburst Drive
Vail, Colorado
Job No. 15-6007R1 Ground Engineering Consultants, Inc. Page 32
Limitations This report has been prepared for The Town of Vail as it pertains to the
proposed Vail Golf Course additions and parking areas as described herein. It may not
contain sufficient information for other parties or other purposes. The owner or any
prospective buyer relying upon this report must be made aware of and must agree to the
terms, conditions, and liability limitations outlined in the proposal.
In addition, GROUND has assumed that project construction will commence by Fall
2015. Any changes in project plans or schedule should be brought to the attention of a
geotechnical engineer, in order that the geotechnical recommendations may be re-
evaluated and, as necessary, modified.
The geotechnical conclusions and recommendations in this report relied upon
subsurface exploration at a limited number of exploration points, as shown in Figure 1,
as well as the means and methods described herein. Subsurface conditions were
interpolated between and extrapolated beyond these locations. It is not possible to
guarantee the subsurface conditions are as indicated in this report. Actual conditions
exposed during construction may differ from those encountered during site exploration.
If during construction, surface, soil, bedrock, or groundwater conditions appear to be at
variance with those described herein, a geotechnical engineer should be advised at
once, so that re-evaluation of the recommendations may be made in a timely manner. In
addition, a contractor who relies upon this report for development of his scope of work or
cost estimates may find the geotechnical information in this report to be inadequate for
his purposes or find the geotechnical conditions described herein to be at variance with
his experience in the greater project area. The contractor is responsible for obtaining
the additional geotechnical information that is necessary to develop his workscope and
cost estimates with sufficient precision. This includes current depths to groundwater,
etc.
The materials present on-site are stable at their natural moisture content, but may
change volume or lose bearing capacity or stability with changes in moisture content.
Performance of the proposed structure and pavement will depend on implementation of
the recommendations in this report and on proper maintenance after construction is
completed. Because water is a significant cause of volume change in soils and rock,
allowing moisture infiltration may result in movements, some of which will exceed
estimates provided herein and should therefore be expected by the owner.
Proposed Golf Course Clubhouse Additions
1610 Sunburst Drive
Vail, Colorado
Job No. 15-6007R1 Ground Engineering Consultants, Inc. Page 33
This report was prepared in accordance with generally accepted soil and foundation
engineering practice in the project area at the date of preparation. GROUND makes no
warranties, either expressed or implied, as to the professional data, opinions or
recommendations contained herein. Because of numerous considerations that are
beyond GROUND’s control, the economic or technical performance of the project cannot
be guaranteed in any respect.
Sincerely,
GROUND Engineering Consultants, Inc.
Carl Henderson, P.E. Reviewed by Brian H. Reck, C.E.G., P.G., P.E.
PIPE SHOULD BE
SURROUNDED ON THE
TOP AND SIDES BY
FREE-DRAINING GRAVEL
WITH LESS THAN 5%
PASSING THE NO. 200
SIEVE, MORE THAN 50%
RETAINED ON THE NO. 4
SIEVE, AND MAXIMUM
PARTICLE SIZE OF 2
INCHES.
NO GRAVEL SHOULD BE
PLACED BELOW THE
PIPE.
Mirafi 140N
or Equal
SLAB-ON-GRADE
BACKFILL
1
10
TYPICAL UNDERDRAIN DETAIL
FIGURE:JOB NO.:
CADFILE NAME:
15-6007 5
6007DRAIN.DWG
PIPE DIAMETER SHOULD BE SIZED FOR ANTICIPATED FLOW RATE,
AND CONSIST OF PERFORATED DRAIN PIPE SLEEVED IN A FILTER
FACRIC SUCH AS MIRIFI 140 OR EQUAL.
THE DRAIN LINE SHOULD BE LAID ON A SLOPE OF 1% OR MORE.
PERFORATIONS SHOULD BE AT 4 O'CLOCK AND 8 O'CLOCK
POSITIONS.
DRAIN TO SUMP WITH PUMP, BACKUP POWER AND ALARM, ETC.
WALL DRAIN
COMPOSITE SUCH AS
MIRADRAIN OR EQUAL
MUST BE IN HYDRALIC
CONNECTION WITH
UNDERDRAIN.
TMTM
PLACE THE DRAIN OUTSIDE THE 45
DEGREE IMAGINARY LINE AS NECESSARY.
NOT TO SCALE
HIGH POINT SHOULD BE MINIMUM
6" BELOW BOTTOM OF GRAVEL
LAYER, SLOPED AT 1% TO
OUTFALL, ELEVATION AND
LOCATION VARIES.
SUGGESTED 12" MIN.
ASTM C33 NO.57
GRAVEL LAYER
NOTE: WATER PROOF, DAMP PROOF AND
WATER STOPPING MEASURES PER
STRUCTURAL /CIVIL DESIGN
CONTROL JOINT
NOTES:
1. THIS IS NOT A DESIGN-LEVEL DRAWING. IT SHOULD BE USED SOLELY FOR GENERAL
INFORMATIONAL PURPOSES ONLY. ACTUAL UNDERDRAIN DESIGN SHOULD BE COMPLETED BY
OTHERS.
2. THE UNDERDRAIN SYSTEM MUST BE TESTED BY THE CONTRACTOR AFTER INSTALLATION
AND BACKFILLING TO VERIFY THAT IT FUNCTIONS PROPERLY.
3. INCLUSION OF THIS FIGURE IN CONSTRUCTION DOCUMENTS IS DONE SO AT THE DOCUMENT
PREPARER'S RISK.
4. THIS DOCUMENT, TOGETHER WITH THE CONCEPTS AND DESIGNS PRESENTED HEREIN, AS AN
INSTRUMENT OF SERVICE, IS INTENDED ONLY FOR THE SPECIFIC PURPOSE AND CLIENT WHICH
IT WAS PREPARED. REUSE OF AND IMPROPER RELIANCE ON THIS DOCUMENT WITHOUT
WRITTEN AUTHORIZATION AND ADAPTATION BY GROUND ENGINEERING CONSULTANTS, INC.
SHALL BE WITHOUT LIABILITY TO GROUND ENGINEERING CONSULTANTS, INC.
PROVIDE BLOCKOUT
OR HYDRAULIC
CONNECTION TO
UNDERDRAIN AT 30'
O.C. MAX
TABLE 1SUMMARY OF LABORATORY TEST RESULTSSample Location Natural Natural Passing Atterberg Limits Swell Water Redox Sulfides AASHTO USCSTest Moisture Dry No. 200 Liquid Plasticity v. 1000 psf Soluble pH Potential Content Resistivity Classifi- Classifi- Soil orHoleDepthContent Density Gravel Sand Sieve Limit Index Surcharge Sulfates cation cation Bedrock TypeNo.(feet) (%) (pcf) (%) (%) (%) (%) (%) (%) (%) (mV) (ohm-cm) (GI)1 2 + 5 15.5 10 67 23 33 12 0.03 7.48 -29 Positive 4,767 A-2-6(0) SC sl. Gravelly, Clayey SAND FILL179.8 39529 NPA-1-A(0) (SW-SM)g slightly Silty, Gravelly SAND2 9 8.6 53 40 7 24 7A-2-4(0) (GW-GC)s sl. Clayey/Silty, Sandy GRAVEL33½8.6 48 45 7A-2-4(0) (GW-GM)s slightly silty, Sandy GRAVEL4 3 11.3 104.7 10 47 43 38 9 -0.4A-4(1) SM sl. Gravelly, Silty SAND FILLN P indicates 'non-plastic.'Job No. 15-6007Gradation