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HomeMy WebLinkAboutEver Vail Soils Report August 2007SOILS REPORT Date October 27, 2008 . . . . . . . . . . It 9 Noe 0 a e � VAIL RESORTS' DEVELOPMENT COMPANY Mauri*llo Planning Group Subsurface Exploration Program and Geotechnical Recommendations for Proposed Commercial /Residential Structures Ever Vail Development Vail, Colorado l r !` � fit.. • �''�iM�! r I £ • ' Mp Mr. Thomas Miller Vail Resorts Development Company 137 Benchmark Road P.O. Box 959 Avon, Colorado 81620 Job Number: 07 -6027 August 31, 2007 .-BROUMD ENGINEERING CONSULTRNTS,INC 41 Inverness Drive East, Englewood, CO 80112 -5412 Phone (303) 289 -1989 Fax (303) 289 -1686 www.groundeng.com Office Locations: Englewood Commerce City Loveland Granby Gypsum TABLE OF CONTENTS Page C Purpose and Scope of Study ....................................................... ............................... 1 Proposed Construction ................................................................ ............................... 2 SiteConditions ............................................................................. ............................... 3 SubsurfaceExploration ................................................................. ............................... 4 LaboratoryTesting ........................................................................ ............................... 6 SubsurfaceConditions .................................................................. ............................... 7 Geotechnical Considerations for Design ....................................... ............................... 10 Seismic Classification ...................................................................... .............................11 Building Foundation Systems .......................................................... .............................12 FloorSystems .............................................................................. ............................... 15 FoundationWalls ......................................................................... ............................... 19 Soluble Sulfates and Corrosivity ................................................... ............................... 20 SurfaceDrainage .......................................................................... ............................... 22 Subsurface Drainage .................................................................... ............................... 25 ProjectEarthworks ........................................................................ ............................... 27 ExcavationConsiderations ........................................................... ............................... 32 UtilityInstallation .......................................................................... ............................... 35 ExteriorFlatwork .......................................................................... ............................... 37 Closure.......................................................................................... .............................40 Site Plan with Test Locations .............................................. ............................... Figure 1 Logsof Test Holes ....................................................... ............................... Figures 2 - 8 Legendand Notes .............................................................. ............................... Figure 9 Interpreted Depth to Denser Alluvium ................................. ............................... Figure 10 Interpreted Elevation of Denser Alluvium ............................ ............................... Figure 11 Interpreted Shallow Groundwater Surface Elevation ........... ............................... Figure 12 Typical Underdrain Detail ................................................... ............................... Figure 13 TABLE OF CONTENTS, Cont. 2 Summary of Asphalt Core Thicknesses . ............................... Summary of Laboratory Test Results .... ............................... ............... Table 1 .... Table 2 and 3 Geophysical Investigations Report, by Zonge Geosciences, Inc ..................... Appendix A �01 Ever Vail Commercial /Residential Structures Vail, Colorado PURPOSE AND SCOPE OF STUDY This report presents the results of a subsurface exploration program performed by GROUND Engineering Consultants, Inc., (GROUND) to develop geotechnical recommendations for design and construction of the proposed infrastructure improvements associated with the Ever Vail development be constructed between Interstate 70 and the South Frontage Road, generally west of West Lionshead Circle, in Vail, Colorado. Our study was conducted in general accordance with GROUND's Proposal No. 0705 -0755, dated May 18, 2007. A field exploration program was conducted to obtain information on subsurface conditions. Material samples obtained during the subsurface exploration were tested in the 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. Geotechnical design parameters and a discussion of geotechnical engineering considerations related to the construction of the proposed facility are included. Job No. 07 -6027 GROUND Engineering Consultants, Inc. Page 1 Ever Vail Commercial /Residential Structures Vail, Colorado PROPOSED CONSTRUCTION Present plans call for construction of an extensive, retail, residential and resort building in the eastern portion of the site. This structure will include approximately 5 stories above -grade and two levels of below -grade parking. In the western portion of the site, a multi -story, concrete parking garage will be constructed, also with two levels of parking below - grade. The facility will extend south of the present Frontage Road / U.S. Highway 6 right -of -way where a gondola base will be constructed. Final building layouts and structural loads have not yet been developed. We understand, however, that none of the below -grade levels will be designed as habitable space. GROUND will be available to review project plans as they are developed. The existing buildings, driveways and parking lots will be demolished. New driveways and sidewalks will be constructed around the buildings comprising the resort facility. A pedestrian bridge on the southern side of the development will carry a sidewalk over Red Sandstone Creek. Both wet and dry underground utilities will be installed to service the facility. The project also will included extensive infrastructure improvements that are addressed in a separate GROUND report. If the proposed construction differs significantly from that described above, GROUND should be notified to re- evaluate the recommendations contained herein. LJ Job No. 07 -6027 GROUND Engineering Consultants, Inc. Page 2 Ever Vail Commercial /Residential Structures Vail, Colorado SITE CONDITIONS The subject property occupies a portion of a topographic terrace overlooking Gore Creek (Vail Creek) from the northern side. The ground has been graded for previous construction, but still slopes overall to the southwest at relatively low gradients, on the order of 2 percent. Red Sandstone Creek, a tributary to Gore Creek, traverses the site from north to south, approximately bisecting the site. Relatively steep banks descended into the Red Sandstone Creek channel. Boulders and cobbles were observed on the channel bottom. The site is bounded by Interstate 70 and the associated right -of -way to the north and northwest; the 1 -70 South Frontage Road bounds the property to the south and southeast. A limited portion of the site lies south of the current Frontage Road alignment, immediately east of Red Sandstone Creek. A resort facility occupied the land to the east and commercial buildings were noted on the properties to the south. At the time of our evaluation, the portion of the site west of Red Sandstone Creek was occupied by retail businesses surrounded by paved parking areas and driveways. To the east of the stream was a Vail Resorts equipment storage and maintenance facility. The parcel south of the frontage road was largely vacant. Landscaped areas with mature trees were scattered across the site. The highway right -of -way between these buildings and 1 -70 was vacant and supported grasses, weeds and scattered bushes and trees. Trees also occupied much of the lower portion of the Red Sandstone Creek channel. Job No. 07 -6027 GROUND Engineering Consultants, Inc. Page 3 Ever Vail Commercial /Residential Structures Vail, Colorado El SUBSURFACE EXPLORATION The subsurface exploration for the project was conducted in June and July, 2007. Data were obtained from a comprehensive program of drilling and sampling supplemented by geophysical (seismic refraction) surveys. Test Holes A total of 33 test holes were drilled throughout the site to evaluate subsurface conditions, including depths to groundwater and bedrock, as well as to retrieve samples for laboratory testing and analysis. The test holes were advanced to depths of approximately 15 to 50 feet with a truck - mounted, continuous flight, power auger rig. A GROUND engineer directed subsurface exploration, logged the test holes in the field, and prepared the samples for transport to our laboratory. Relatively undisturbed samples of the subsurface materials were taken with a 2 -inch I.D. "California" -type liner sampler. The sampler was 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. Disturbed samples of the subgrade materials were obtained using a Standard Penetration Test sampler in general IV accordance with ASTM D1586. Penetration resistance values (blows per distance driven, typically 12 inches), when properly evaluated, indicate the relative density or consistency of soils and bedrock. Depths at which the samples were taken and associated penetration resistance values are shown on the test hole logs. Six of the test holes were completed as temporary piezometers allowing on -going re- checks of the groundwater levels at those locations. Slug tests were performed in two of those piezometers to allow field evaluations of local hydraulic conductivity. The approximate locations of the test holes are shown in Figure 1. Logs of the test holes are presented on Figures 2 through 8. Explanatory notes and a legend are provided on Figure 9. Geophysical Surveys Two multi - channel refraction seismic surveys were performed by Zonge Geosciences, Inc. ( Zonge) to provide additional data between test holes regarding the depths and distribution of earth materials. Data were collected by means of conventional, multi - channel seismic refraction methods using an energy source as well as refraction microtremor methodology that makes use of ambient seismic energy. The Zonge report, dated August 24, 2007, is presented in Appendix A. E_ Job No. 07 -6027 GROUND Engineering Consultants, Inc. Page 4 Ever Vail Commercial /Residential Structures Vail, Colorado Pavement Coring Seven 2 -inch diameter cores of the existing asphalt pavement in the (current) Frontage Road / U.S. Highway 6 were collected with a trailer- mounted coring rig to evaluate the thickness of the existing pavements. The resultant holes were backfilled with "cold patch." A summary of the asphalt depths encountered is presented on Table 1. r: Job No. 07 -6027 GROUND Engineering Consultants, Inc. Page 5 Ever Vail Commercial /Residential Structures Vail, Colorado 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 Atterberg limits. Hydraulic conductivity, water - soluble sulfate content, pH and resistivity tests were performed on selected samples as well. Laboratory tests were performed in general accordance with applicable ASTM protocols as tabulated below. Data from the laboratory testing program are summarized in Tables 2 and 3. TEST STANDARD Moisture Content ASTM D2216 Percent Passing the #200 Sieve ASTM D1140 Gradation ASTM D422 Atterberg Limits ASTM D4318 Water - Soluble Sulfates CPL 2103 H ASTM G51 Electrical Resistivity ASTM G187 Hydraulic Conductivity ASTM D5804 Job No. 07 -6027 GROUND Engineering Consultants, Inc. Page 6 Ever Vail Commercial /Residential Structures Vail, Colorado SUBSURFACE CONDITIONS The subsurface conditions encountered in the test holes generally consisted of sands, gravels, cobbles and boulders interpreted to be relatively recent to older (Holocene- to Upper Pleistocene) alluvial (stream -laid) deposits associated with Gore Creek and Red Sandstone Creek. A general distinction was noted between less dense alluvial deposits (Penetration Resistance Values generally from about 10 to 45) at shallower depths and the underlying denser alluvium (Penetration Resistance Values generally greater than 50). It should be noted in addition that refusal was encountered by the drilling equipment at various depths and locations across the site. The interpreted depth to this transition from moderately dense to very dense alluvium is depicted on Figure 10, based on interpolation between and extrapolation beyond the conditions encountered in the individual test holes. The same data were used to develop Figure 11, depicting the interpreted elevation of the top of the denser, lower materials. Inspection of Figures 10 and 11 indicates that the top of the very dense materials appeared to descend southwestward, similarly to the ground surface, as well as becoming lower in generally along the alignment of Red Sandstone Creek. The depth to this transition is 10 to 15 feet across much of the site, but again is markedly greater near and northeast of the present Red Sandstone Creek channel. This likely reflects a former location of the channel of that stream, in- filled by past grading or a natural shift in the channel alignment. Another area where the transition to dense materials is noticeably lower is in the area of Test Hole 15 in the eastern portion of the site. This feature may reflect a former borrow area in which the lower density materials are locally - derived backfill soils. The alluvial deposits were not fully penetrated by GROUND's test holes, that extended to depths as great as 52 feet. The geophysical surveys performed for this evaluation, however, indicated that materials were present at depth exhibiting compressive (P -) wave velocities of 9,000 feet per second (ft/sec) and higher. These velocities are interpreted to represent very dense, hard bedrock materials, likely granitic rock. The depths at which the geophysical surveys indicated this (likely) granitic rock was present ranged from approximately 35 to more than 50 feet below existing grades. The inferred top -of- granite surface was highly irregular, however. Therefore, the Contractor should be prepared to encounter very resistant, intact bedrock locally at depths shallower than 35 feet. The transition from the upper alluvial deposits to the lower, denser alluvium appears to correspond generally to P -wave velocities in the range of 3,500 to 4,000 EA Job No. 07 -6027 GROUND Engineering Consultants, Inc. Page 7 Ever Vail Commercial /Residential Structures Vail, Colorado ft/sec. (For example, the deeper zone of less dense alluvium around Test Hole 15 appears to be discernable on Figure 4 of the Zonge report of August 24, 2007.) The intermediate velocities (5,000 to 9,000 ft/sec t) may represent Maroon Formation materials that are depicted on published geologic maps as underlying the general project area. The Maroon Formation consists, in general, of sandstones, siltstones and conglomerates with local limestone beds. Therefore, much of the material exhibiting velocities lower than 9,000 ft/sec will be dense and difficult to excavate, as well. Fill soils were observed along 1 -70 and were encountered locally in the test holes. Some fill soils may not be denoted as such on the test hole logs due to similarity to the native materials. Delineating the complete vertical and lateral extents of any fills was beyond our present scope of services. Encountering fill soils at any location at the Ever Vail site should not be considered a Changed Condition. Groundwater was observed commonly in the test holes at relatively shallow depths, typically between 15 and 20 feet. In the project area, shallow groundwater levels are related to the stage of Gore Creek. Figure 12 depicts the interpreted elevation of the shallow groundwater table, again based on interpolation between and extrapolation beyond the water levels measured in the test holes. The water level contours suggest that shallow groundwater is flowing southwestward across the site, toward Gore Creek. A distinct reentrant is depicted near Red Sandstone Creek likely representing more rapid flow (drainage) along the present or former channel of that creek. (Such stream channel axes commonly are locations where coarser alluvium will be concentrated, in this case coarse cobbles and boulders.) Groundwater levels should be anticipated to fluctuate, however, in response to annual and longer -term cycles of precipitation — particularly spring snow melts, applied irrigation, and surface drainage. Fill ranged from silty sands with gravel to silty to clayey gravels. They were slightly moist to moist, slightly to moderately plastic, loose to medium dense, and brown to pale gray in color. Although not identified in the test holes, based on prior construction on the site and adjacent areas, construction debris likely is present in the fill soils locally. Native Sands were fine to coarse, and silty to clayey with gravel commonly. Scattered cobbles and boulders were noted locally. They were moist to wet, low plastic, loose to medium dense, and brown to gray in color. Native Sands and Gravels ranged from silty to clayey to gravelly sands to silty to clayey gravels. Cobbles and boulders were common throughout the alluvial section, but Job No. 07 -6027 GROUND Engineering Consultants, Inc. Page 8 Ever Vail Commercial /Residential Structures Vail, Colorado particularly in the lower materials. They were fine to coarse grained, dry to wet, non - plastic to moderately plastic, locally loose to moderately dense to very dense, and pale gray to brown -gray in color. Bedrock Materials were not encountered in the test holes. Based on their geophysical data, however, bedrock materials likely include very hard, resistant crystalline rock and depth, possibly overlain by hard sandstones, siltstones and conglomerates of the Maroon Formation. Hydraulic Conductivity The results of GROUND's hydraulic conductivity testing are listed below. Tests were performed to determine hydraulic conductivity (K in our laboratory on 2 relatively small - volume samples retrieved from the test holes. Two field tests for hydraulic conductivity ( "Slug Tests ") were performed as well. Laboratory Measurements TH -13 at 20 feet: K = 1.5 x 10 cm /s TH -16 at 24 feet: K = 1.3 x 10 cm /s ® Field Testing TH -6 at 30 to 40 feet: K = 1.3 x 10 -4 cm /s TH -15 at 20 to 30 feet: K = 2.2 x 10 cm /s These values, with the exception of TH -13 at 20 feet are typical of clean to silty sands. (The fines were significantly more clayey in the sample from TH -13 at 20 feet) Based on the percentage of fines typically encountered in the site soils, these values likely are generally representative of the site soils. It should be noted, however, that hydraulic conductivity values vary over many orders of magnitude in natural sediments, and that significant changes in hydraulic conductivity can occur abruptly. Job No. 07 -6027 GROUND Engineering Consultants, Inc. Page 9 Ever Vail Commercial /Residential Structures Vail, Colorado GEOTECHNICAL CONSIDERATIONS FOR DESIGN In general, the Ever Vail site is underlain by moderately dense to very dense, granular soils. These materials will provide good foundation support; no data were developed that suggested significant potentials for soils heave or collapse. The proposed buildings can be supported on spread footing foundation systems, although other foundation types, such as mat or driven pile foundations could be used, as well. Where driven pile foundations are selected, systematic air - percussion pre - drilling will be needed to advance the piles. Because of the density of the coarse granular soils, difficult excavation conditions will be encountered throughout the site, except where structures are founded at very shallow depths. In addition, groundwater is relatively shallow, and should be anticipated in large volumes in all except the shallowest project excavations. Buildings with below -grade levels will need to be protected by permanent de- watering systems. These systems should be designed to remove large volumes of water throughout the design -lives of the structures. E LJ Job No. 07 -6027 GROUND Engineering Consultants, Inc. Page 10 Ever Vail Commercial /Residential Structures Vail, Colorado 0 SEISMIC CLASSIFICATION The project area falls within Seismic Performance Category A based on AASHTO guidelines, and is considered to have a low probability for large, damaging earthquakes. Based on the conditions encountered in the test holes, extrapolating available data to depth, the site falls within the parameters of a Seismic Site Class C site, in accordance with 2003/2006 IBC. However, if a quantitative assessment of the classification is needed, deeper drilling (to at least 100 feet) and down -hole shear wave velocity testing will be required. A proposal for this work can be provided upon request. Compared with other regions of Colorado, recorded earthquake frequency in the project area is relatively low. Eil 1 *1 Job No. 07 -6027 GROUND Engineering Consultants, Inc. Page 11 Ever Vail Commercial /Residential Structures Vail, Colorado C BUILDING AND GONDOLA BASE FOUNDATION SYSTEMS The principle building structures will bear depths of more than 20 feet below existing grades. We anticipate that the proposed gondola base also will bear at depths more than 20 feet. Therefore, all of these facilities should be supported on continuous and isolated spread footings bearing in the dense, native sands and gravels. The geotechnical criteria presented below may be observed for spread footing foundation systems. The construction details should be considered when preparing project documents. 1) Footings should bear on dense, in -place native, granular soils. 2) Footings bearing on a properly prepared surface in dense, in -place native, granular soils may be designed for an allowable soil bearing pressure (Q) of 5,000 psf. This value may be increased by 1 /3 for transient loads such as wind or seismic loading. Based on this bearing capacity, we anticipate direct compression of the foundation soils upon loading to be on the order of 1 inch. 3) In order to achieve the above - recommended capacity, footing excavation operations and the prepared bearing surface must be observed by the Geotechnical Engineer. Firm native soils materials may be disturbed by the excavation process or de- watering. Local areas of less dense materials may be exposed at foundation bearing elevations. All such unsuitable materials should be excavated and replaced with "dental' concrete that exhibits a minimum compressive strength of at least 2,000 psi. 4) In order to reduce differential settlements between footings or along continuous footings, footing loads should be as uniform as possible. Differentially loaded footings will settle differentially. 5) Spread footings should have a minimum lateral dimension of 16 or more inches for linear strip footings. Isolated pad footings should have a minimum, horizontal footing dimension of at least 24 inches. Actual footing dimensions, however, should be determined by the Structural Engineer, based on the design loads. v Job No. 07 -6027 GROUND Engineering Consultants, Inc. Page 12 Ever Vail Commercial /Residential Structures Vail, Colorado 6) Continuous foundation walls should be reinforced top and bottom to span an unsupported length of at least 10 feet. 7) The lateral resistance of spread footings will be developed as sliding resistance of the footing bottoms on the foundation materials, and by passive soil pressure against the sides of the footings. Sliding friction at the bottom of footings bearing on common fill may be taken as 0.50 times the vertical dead load. A passive earth pressure of 450 psf per foot of embedment may be used, to a maximum of 4,500 psf. The upper 1 foot of embedment should not be relied upon for passive resistance, however. 8) Compacted fill placed against the sides of the footings should be compacted to at least 96 percent relative compaction in accordance with the recommendations in the Project Earthworks section of this report. 9) Care should be taken when excavating the foundation to avoid disturbing the supporting materials. Hand excavation or careful backhoe soil removal may be required in excavating the last few inches. 10) Foundation soils may be disturbed or deform excessively under the wheel loads of heavy construction vehicles as the excavations approach footing levels. Construction equipment should be as light as possible to limit development of this condition. The use of track - mounted vehicles is suggested because they exert lower contact pressures. The movement of vehicles over proposed foundation areas should be restricted. 11) Recommended footing bearing elevations are at or just below the local water levels. Therefore, it will necessary to de -water the footing excavations during construction. De- watering should not be conducted by pumping from inside footing excavations. This may decrease the supporting capacity of the materials. A Geotechnical Engineer should be retained to observe and test all footing excavations prior to placement of reinforcing steel or concrete. Ancillary Buildings We assume that the development may include various support buildings and other structures without below -grade levels. The above recommendations are generally applicable to such structures, except as follows: Job No. 07 -6027 GROUND Engineering Consultants, Inc. Page 13 Ever Vail Commercial /Residential Structures Vail, Colorado • Footings bearing on a properly prepared surface in firm, in -place native, granular soils may be designed for an allowable soil bearing pressure (Q) of 3,000 psf. • Soft or loose soils likely will be exposed at foundation bearing elevations. Firm native soils materials may be disturbed by the excavation process. All such unsuitable materials should be excavated and replaced with "dental" concrete exhibiting a minimum compressive strength of at least 2,000 psi or properly compacted fill, or the foundations deepened. Footing excavation operations and the prepared bearing surface must be observed by the Geotechnical Engineer. • Footings should be placed at a bearing elevation 4 or more feet below the lowest adjacent exterior finish grades for frost protection. Because of the depth of proposed installation, no additional deepening of the foundations is required. Passive resistance against the sides of footings should be neglected. El U Job No. 07 -6027 GROUND Engineering Consultants, Inc. Page 14 Ever Vail Commercial /Residential Structures Vail, Colorado �110 FLOOR SYSTEMS As discussed in the Geotechnica! Considerations for Design section of this report, a concrete slab -on -grade floor, bearing on a properly prepared subgrade may be used for the lowest levels (parking levels) of the proposed structures. The following criteria should be observed for design and construction of slab -on -grade concrete floors: 1) A slab -on -grade floor system should placed on properly prepared subgrade consisting of dense native, granular soils. 2) An allowable vertical soil modulus (Kv) of 175 pci may be used for design of concrete slabs bearing on a properly prepared subgrade. 3) A Geotechnical Engineer should be retained to observe the prepared surfaces on which the floor slabs will be cast prior to placement of reinforcement. Loose, soft or otherwise unsuitable materials should be excavated and replaced with properly compacted granular fill. 4) Concrete slabs -on -grade should be constructed and cured in accordance with applicable industry standards and 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. Job No. 07 -6027 GROUND Engineering Consultants, Inc. Page 15 Ever Vail Commercial /Residential Structures Vail, Colorado 5) Floor slabs should be adequately reinforced. Recommendations based on structural considerations for slab thickness, jointing, and steel reinforcement in floor slabs should be developed by the Structural Engineer. 6) As part of the building underdrain system discussed in the Subsurface Drainage section of this report, GROUND recommends placement of a properly compacted layer of free - draining gravel, 12 or more inches in thickness, beneath each slab. 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 3 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. Ancillary Buildings Design and construction of slab -on -grade floors for ancillary structures also should observe the following: 1) A Geotechnical Engineer should be retained to observe the prepared surfaces on which the floor slabs will be cast prior to placement of reinforcement. Loose, ® soft or otherwise unsuitable materials should be excavated and replaced with properly compacted fill, placed in accordance with the recommendations in the Project Earthworks section of this report. 2) 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, 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. 3) Interior partitions resting on floor slabs should be provided with slip joints 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 2 or more inches of vertical movement, should be considered. If slip joints are placed at the tops of walls, in the event that the floor slabs move, it is likely that the wall will show signs of distress, especially where the floors and interior walls meet the exterior wall. C Job No. 07 -6027 GROUND Engineering Consultants, Inc. Page 16 Ever Vail Commerciai /Residential Structures Vail, Colorado 4) An on -grade concrete slab should be properly cured and provided with joints to control random shrinkage cracking which results from concrete curing. Slab control joints be spaced no more than 10 feet on center, both ways, and extend to an effective depth. This spacing is based on geotechnical considerations. Joint layout based on the slab design may require additional or deeper joints. 5) 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 the Structural Engineer. 6) All plumbing lines should be carefully tested before operation. Where plumbing lines enter through the floor, a positive bond break should be provided. Flexible connections allowing 2 or more inches of vertical movement or more should be provided for slab- bearing mechanical equipment. 7) 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, 4 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. 8) A vapor barrier beneath a building floor slab can be beneficial with regard to reducing exterior moisture moving into the building, but can retard downward drainage of construction moisture. Uneven moisture release can result in slab curling. Elevated vapor fluxes can be detrimental to the adhesion and L•` Job No. 07 -6027 GROUND Engineering Consultants, Inc. Page 17 Ever Vail Commercial /Residential Structures Vail, Colorado L .J performance of many floor coverings and may exceed various flooring manufacturers' usage criteria. Therefore, in light of the several, potentially conflicting effects of the use vapor - barriers, the Owner and the Architect and /or Flooring Contractor should weigh the performance of the slab and appropriate flooring products in light of the intended building use, etc., during the floor system design process and the selection of flooring materials. Use of a plastic vapor- barrier membrane may be appropriate for some buildings or building areas and not for others. E l- Job No. 07 -6027 GROUND Engineering Consultants, Inc. Page 18 Ever Vail Commercial /Residential Structures Vail, Colorado � -1 FOUNDATION WALLS We understand that the proposed below -grade parking levels will entail relatively tall below -grade foundation walls. These walls will be laterally supported and can be expected to undergo only a limited amount of deflection comprising an "at- rest" condition. We also understand that they will be internally braced by the floor levels above the lowest level. We understand that the excavations for the proposed below -grade parking levels will be on the order of 30 to 40 feet in depth. A temporary shoring system to be designed by the Contractor will support these near - vertical excavation slopes and largely preserve the exposed soils in their native condition. These cuts will be made close to the proposed foundation walls, i.e., 3 to 5 feet. We recommend that this narrow void between the shored cut slope and the foundation wall be backfilled with a coarse, clean, open - graded granular material such as 2 -inch crushed rock. Based on these conditions, GROUND recommends that the foundation walls be designed to resist a rectangular distribution of lateral earth pressure, taking an (at -rest) value of 25 pcf to be characteristic of the site soils. Assuming that the foundation wall drainage systems are effective, hydrostatic loading need not be added to the lateral loading on the foundation walls. The 'at rest' loading recommended above is for well- drained conditions with a horizontal upper backfill surface. The additional loading of an upward sloping backfill, as well as loads from traffic, stockpiled materials, etc., should be included in foundation wall design. 0 Job No. 07 -6027 GROUND Engineering Consultants, Inc. Page 19 Ever Vail Commercial /Residential Structures Vail, Colorado L I- SOLUBLE SULFATES AND SOIL CORROSIVITY Water - Soluble Sulfates The concentrations of water - soluble sulfates measured in selected samples retrieved from the test holes were up to approximately 0.02 percent by weight (See Table 2). Such concentrations of water - soluble sulfates represent a negligible environment for 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 and PCA guidelines, GROUND makes no recommendation for use of sulfate- resistant cement in concrete exposed to site soil and bedrock. Soll Corrosivity Measurements of soil acidity (pH) and electrical resistivity were made to provide a general assessment of the potential for corrosion of ferrous metals installed in contact with earth materials, based on the conditions existing at the time of GROUND's evaluation. Test results are summarized in Table 2. Values of pH below 7 (neutral) indicate acidic conditions; values greater that 7 indicate basic conditions, on a logarithmic scale. Testing indicated pH valued from about 7.9 to 8.7, which indicating that the tested materials are somewhat basic. This will not contribute greatly to corrosion. Electrical resistivity is related both to a material's moisture content and to the concentrations of dissolved salts and other conductive constituents in the soil pore water. Measurement of electrical resistivity indicated values ranging from about 2,100 to 8,500 ohm - centimeters in selected samples of the site soils. Resistivities between 2,000 and 4,500 ohm - centimenters are classified as representing a 'fair' corrosive environment for ferrous metals in contact with site soils, on a scale of 'bad,' 'fair,' 'good' and 'excellent' as presented in the "Handbook of Steel Drainage and Highway Construction Products" published by the American Iron and Steel Institute. Resistivities between 4,500 and 6,000 ohm - centimeters are classified as 'fair,' and greater than 6,000 ohm - centimeters as 'excellent.' Therefore, the overburden soils appear to comprise a variable, but overall a moderately to mildly corrosive environment for metals. Additional testing may be appropriate to facilitate corrosion - resistant design of individual structures or elements. 0 Job No. 07 -6027 GROUND Engineering Consultants, Inc. Page 20 Ever Vail Commercial /Residential Structures Vail, Colorado Corrosive conditions can be mitigated by use of materials not vulnerable to corrosion, heavier gauge materials with longer design lives, or cathodic protection systems. If additional information or recommendations are needed regarding soil corrosivity, GROUND recommends contacting 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 the corrosion potentials significantly. L111 C] Job No. 07 -6027 GROUND Engineering Consultants, Inc. Page 21 Ever Vail Commercial /Residential Structures Vail, Colorado SURFACE DRAINAGE The following drainage precautions should be observed during construction and maintained at all times after the facility has been completed. If the drainage measures below are not implemented and maintained effectively, the movement estimates provided in this report could be exceeded. Systematic maintenance is particularly important at this site due to the heavily irrigation adjacent slopes. 1) Excessive wetting or drying of the foundation excavations and under -slab area should be avoided during construction. 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 landscaped areas and 3 inches in the first 10 feet in areas where hardscaping covers the ground adjacent to the addition. (It may be necessary to incorporate ramps or other measures into project design to implement this recommendation while complying with access requirements.) In no case should water be allowed to pond near or adjacent to foundation elements. Ponding will lead to increased infiltration and post- construction building movements. 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 or 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. E-4 Job No. 07 -6027 GROUND Engineering Consultants, Inc. Page 22 Ever Vail Commercial /Residential Structures Vail, Colorado 3) The ground surface near foundation elements should be able to convey water away readily. Ground coverings that direct water downward rather than away from the addition should not be used to cover the ground surface near the foundations or other improvements sensitive to post- construction soil movements. Cobbles or other materials that tend to act as baffles and restrict surface flow should not be Used. Correspondingly, near other project improvements such as hardscaping, where the ground surface does not convey water away readily additional post - construction movements and distress should be anticipated. 4) Roof downspouts and drains should discharge well beyond the perimeters of the structure foundations, or be provided with positive conveyance off -site for collected waters. Downspouts should not discharge into a building underdrain system. 5) 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 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 conveyance well away from the foundation soils or off -site for collected waters. 6) 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 C! ' J' Job No. 07 -6027 GROUND Engineering Consultants, Inc. Page 23 Ever Vail Commercial /Residential Structures Vail, Colorado .111 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. Perforated "weed barrier" membranes, which allow ready evaporation from the underlying soils may be used. n E Job No. 07 -6027 GROUND Engineering Consultants, Inc. Page 24 Ever Vail Commercial /Residential Structures Vail, Colorado SUBSURFACE DRAINAGE Building Underdrains Because of the presence of a shallow water table, well above the elevations at which the lower levels of the principle buildings will be constructed, and because of the potential for saturation of the near - surface soils during annual snow - melt, the proposed buildings should be protected by underdrain systems. These underdrain systems will be, in effect, permanent de- watering systems. The underdrain systems should consist of perforated PVC collection pipe at least 6 inches in diameter, non - perforated PVC discharge pipe at least 6 inches in diameter, free - draining gravel, and filter fabric. (Actual pipe sizing should be based on water volumes realized in deep project excavations during construction.) The free - draining gravel should contain less than 3 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. The gravel surrounding the collection pipe should be wrapped with filter fabric to reduce the migration of fines into the drain system. 'Clean out' access points should be provided at intervals along the system to facilitate 40 maintenance. A typical, cross - section detail an underdrain the described above is presented on Figure 13. The actual layout, outlets, etc., should be designed by the Civil Engineer. Each building should have an exterior perimeter underdrain. The buildings also should have lateral underdrains spaced no more than 30 feet apart beneath the building. The high point(s) for the pipe flow line(s) should be at least 12 inches below the bottoms of the floor slabs. The pipe for the interceptor drain system should be graded to drain effectively to one or more sumps from which water can be removed by pumping, or, in the case of small structures without below -grade levels, to outlet(s) for gravity discharge. Along the below -grade building foundation walls, the perimeter underdrain gravel should extend upward to within 12 inches of the backfill surface behind the wall or the wall should be backed with a layer of synthetic drainage medium, e.g., an appropriate MiraDrain product or equivalent. The gravel or drainage product backing the wall should be in hydraulic connection with the wall heel drain. If gravel is selected, it should be separated from the enclosing soils by a layer of filter fabric to reduce the migration of fines into the drainage system. Damp - proofing should be applied to the back (exterior) side of foundation walls. Job No. 07 -6027 GROUND Engineering Consultants, Inc. Page 25 Ever Vail Commercial /Residential Structures Vail, Colorado C E'�� For the larger buildings, where high water volumes are anticipated due to the extent of the below -grade levels, volumes for preliminary system sizing may be based on the estimated water flows provided in the Excavation Considerations section of this report. The final system design should be based on the water volumes realized during project construction. The underdrain system pumps should be redundant and supplied with auxiliary power systems in case of power loss. The perimeter 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. Drainage Between Shored Slopes and Buildings A void will be created between the shored excavation slopes and the building foundation walls. GROUND recommends that this narrow void between the shored cut slope and the foundation wall be backfilled with a coarse, clean, open - graded granular material such as 2 -inch crushed rock. This crushed rock fill should be in hydraulic continuity with the perimeter underdrain system. A layer of filter fabric should be placed over this material at the top to reduce infiltration of fines into it. Job No. 07 -6027 GROUND Engineering Consultants, Inc. Page 26 Ever Vail Commercial /Residential Structures Vail, Colorado PROJECT EARTHWORKS General Considerations Because the site has been graded previously, we anticipate cuts and fills of limited nominal depth to construct the building pads and hardscape areas, etc. Deeper excavations wiil be needed to install utilities and excavations at least 35 feet in depth are planned to install the below -grade parking levels for the facility on the eastern half of the site. Site grading should be planned carefully to provide positive surface drainage away from the buildings, and all pavements, utility alignments, and flatwork. Surface diversion features should be provided around paved areas to prevent surface runoff from flowing across the paved surfaces. 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 building construction. Prior to earthwork construction, existing structures, 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 capped at the margins of the property. The limited volumes of topsoils present on the site should not be incorporated into ordinary fills. Instead, topsoils should be stockpiled during initial grading operations for placement in areas to be landscaped or for other approved uses. Areas of previously placed fill soils were encountered in the test holes and other fills may be present across the site. These fill soils should be tested, and as necessary, excavated and replaced with properly moisture - conditioned and compacted fill. Fill Materials Crushed Rock Fill Materials used as crushed rock fill should be free of deleterious materials and consist of 2 -inch nominal, angular, open graded, crushed rock. Select. Granular Fill Materials used as select, granular fill should be free of deleterious materials and meet the criteria for CDOT Class 1 Structure Backfill as tabulated below. Job No. 07 -6027 GROUND Engineering Consultants, Inc. Page 27 Ever Vail Commercial /Residential Structures Vail, Colorado v CDOT CLASS 1 STRUCTURE BACKFILL (703.08) Sieve Size or Parameter Acceptable Range 2 -inch 100% passing No. 4 30% to 100% passing No. 50 10% to 60% passing No. 200 5% to 20% passing Liquid Limit < 35 Plasticity Index < 6 Common Fill refers to fill materials free of deleterious materials, and approved by the Geotechnical Engineer, but not meeting the requirements of select, granular fill. Crushed rock or similar, open - graded materials should not be used as common fill. Use of On -Site Materials as Fill Site soils including both fill and native materials, free of construction debris, organic materials and other deleterious materials are, in general, suitable for placement as compacted fill. Excavated materials will include boulders and coarse cobbles that likely will require additional processing to be included in project fills. Boulders as well as cobbles and rock fragments larger than 6 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 proposed fills. The 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 earthworks. Standard recommendations that likely will be generally applicable can be found in Section 203 of the CDOT Standard Specifications for Road and Bridge Construction (2005). A significant proportion of coarse site soils when excavated likely can be crushed for aggregate for use on site to reduce the volumes of imported materials. Materials that likely can be generated include CDOT Class 1 Structure Backfill, CDOT Class 6 Aggregate Base, drainage rock and /or pipe bedding. Imported Fill Materials If it is necessary to import material to the site as common fill, the imported soils should be free of organic material, and other deleterious materials. Imported material should have less than 40 percent passing the No. 200 Sieve and should have a plasticity index of less than 20. The criteria for materials to be imported Job No. 07 -6027 GROUND Engineering Consultants, Inc. Page 28 Ever Vail Commercial /Residential Structures Vail, Colorado J as select granular fill are given above. All materials proposed for import should be tested and approved prior to transport to the site. 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. 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. In project excavations, sloughing or removal of large clasts may result in local voids that require filling. In such cases, dental concrete or properly densified crushed rock fill or granular fill, depending on location, should be used to restore lines and grades. 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. Soils that classify as GP, GW, GM, GC, SP, SW, SM, or SC in accordance with the USCS classification system (granular materials) should be compacted to 96 or more percent of the maximum modified Proctor dry density at moisture contents within 2 percent of optimum moisture content as determined by ASTM D1557, the modified Proctor." Soils that classify as ML, MH, CL or CH should be compacted to 96 percent of the maximum standard Proctor density at moisture contents from 1 percent to 3 percent above the optimum moisture content as determined by ASTM D698, the "standard 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 moisture contents during placement and compaction. We anticipate that some on -site soils may exhibit significant pumping, rutting, and deflection at moisture contents near optimum and above. Some site materials classify as non - plastic to slightly plastic silty sands. In our experience, achieving and maintaining compaction in such soils can be very difficult, particularly if water contents are not monitored closely. The Contractor should be E__ Job No. 07 -6027 GROUND Engineering Consultants, Inc. Page 29 Ever Vail Commercial /Residential Structures Vail, Colorado El prepared to handle soils of this type, including the use of chemical stabilization, if 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. To achieve adequate compaction near the outer faces of fill slopes, it may be beneficial to over -build the slopes and trim them back. Use of Squeegee Relatively uniformly graded fine gravel or coarse sand, i.e., squeegee," or similar materials commonly are proposed for backfilling foundation excavations, portions of utility trenches and other areas where employing compaction equipment is difficult. In general, GROUND does not recommend this procedure for the following reasons: 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. Quality Assurance A Geotechnical Engineer should be retained to observe project excavations prior to placement of fill. The Geotechnical Engineer also should observe L Job No. 07 -6027 GROUND Engineering Consultants, Inc. Page 30 Ever Vail Commercial /Residential Structures Vail, Colorado : earthwork operations and test the soils. The Geotechnical Engineer should provide a written declaration stating that the project site, including the building pad area, was filled with acceptable materials and was placed in general accordance with the requirements outlined in this report or otherwise specified for the project. It should be noted that in the later stages of projects such as construction of the proposed facility, multiple sub - contractors commonly are installing or adjusting /replacing components of the project simultaneously. These can include utility laterals, electrical boxes, sidewalk access ramps, lighting fixtures and other components. In order to facilitate proper observation and testing of the associated earthworks, GROUND recommends that the Contractor verify that his sub - contractors mobilize the necessary equipment and personnel to moisture - condition and compact disturbed or excavated soils effectively. The Contractor also should coordinate with his sub- contractors to ensure that these local earthwork operations are observed with sufficient frequency, and the soils tested, by the Geotechnical Engineer. Settlements Settlements will occur in filled ground, typically on the order of 1 to 2 percent of the fill depth. For a 6 -foot fill, this corresponds to settlement on the order of 1 ® inch, without imposition of foundation loads. If fill placement is performed properly and is tightly controlled, in GROUND's experience the majority of that settlement will take place during earthwork construction. The remaining potential settlements likely will take several months or longer, to be realized. Cut and Filled Slopes Permanent site slopes supported by on -site soils up to 5 feet in height may be constructed no steeper than 2'/2:1 (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. 0 Job No. 07 -6027 GROUND Engineering Consultants, Inc. Page 31 Ever Vail Commercial /Residential Structures Vail, Colorado E EXCAVATION CONSIDERATIONS Excavation Difficulty Test holes for subsurface exploration were advanced to the depths indicated on the test hole logs by means of truck - mounted, flight auger equipment. Drilling was difficult and penetration resistance values were high in the lower, denser alluvium. Refusal was encountered commonly (See the test hole logs.) and auger was broken repeatedly as the test holes were advanced in the latter materials. In the shallower, less dense alluvium we anticipate no unusual excavation difficulties, in general, for the proposed construction in these materials with conventional, heavy -duty excavating equipment in good working condition. These materials include coarse cobbles and boulders locally. The Contractor should be prepared to excavate, handle and process these materials, and export them from the site, as necessary. In the lower, denser alluvium, however, coarse cobbles and boulders appeared to comprise a higher percentage of the alluvium and all the alluvial materials were more densely packed. Excavations into these soils may require very heavy or specialized equipment. Breaking equipment may be cost effective to facilitate project excavations, particularly in trenches. The Contractor should anticipate increased wear on his equipment and higher than typical maintenance costs. The geophysical data obtained for this evaluation indicated P -wave velocities greater than 9,000 ft/sec, interpreted to indicate very resistant materials, as shallow as 35 feet below existing grades. (See Appendix A.) Locally, such conditions may be encountered still more shallowly. Velocities greater than about 3,500 to 4,000 ft/sec appear to indicate the lower, denser alluvial deposits as well as still denser materials below the alluvium. Similar to the test hole data, the seismic data indicates that difficult excavation condtions will be encountered at relatively shallow depths in many areas. Groundwater Relatively shallow groundwater was encountered commonly across the site. The Contractor should anticipate encountering water near and below approximate elevations depicted on Figure 12 and be prepared to work in the presence of groundwater. (Even shallower excavations locally may expose wet soils or seepage. Where seepage or groundwater is encountered in shallow project excavations, a Geotechnical Engineer should be retained to evaluate the conditions and provide additional recommendations, as appropriate.) It should be noted that the water levels represented on that figure were based on data obtained during the summer. Higher Job No. 07 -6027 GROUND Engineering Consultants, Inc. Page 32 Ever Vail Commercial /Residential Structures Vail, Colorado r: water levels should be anticipated during seasons of higher rainfall or snow melt. The alluvial deposits at the site were moderately to highly permeable and relative rapid water flows and high water volumes likely will be. generated by excavations below the local water table. The de- watering system(s) should be designed for the Contractor by a registered engineer. The risk of slope instability will be significantly increased in areas of seepage along the excavation slopes. Based on data obtained for this study, estimate on the order of 0.0006 to 0.0020 gallons per day (gpd) per exposed face ft below the local water table. Setting de- watering well points sufficiently below the bottom of a given excavation can significantly reduce the volume of water entering through the excavation floor. Larger excavations likely will require at least a limted number of interior well points, as well. Temporary Slopes and Shoring We recommend that temporary, un- shored excavation slopes up to 20 feet in height be cut no steeper than 1'/2:1 (horizontal : vertical) in the coarse, granular shallow alluvial soils and similar fill soils in the absence of seepage. The shallower, less dense alluvial soils and similar fill soils typically extend to depths of about 10 to 15 feet below existing grades. (See Figure 10.) Where the lower portions of temporary slopes expose the deeper, denser alluvial soils, those portions may be cut as steeply as 1:1 (horizontal : vertical) in the absence of seepage. Significant sloughing on the slope faces should be anticipated at this angle due to the cohesionless nature much of sands above the water table. Local conditions encountered during construction, such as groundwater seepage, loose sand, or soft, wet materials, 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, which ever is greater. Should site constraints prohibit the use of the recommended slope angles, then temporary shoring should be used. Temporary shoring designed to allow the soils to deflect sufficiently to utilize the full active strength of the soils may be designed for lateral earth pressures computed taking an angle of internal friction of 32 degrees, a moist unit weight of 125 pcf and a cohesion of 0 to be characteristic of the site soils. Lateral earth pressure calculations for shoring design also should include surcharge loads exerted by equipment, traffic, seepage forces, material stockpiles, etc. Actual shoring system(s) should be designed for the Contractor by a registered engineer. Job No. 07 -6027 GROUND Engineering Consultants, Inc. Page 33 Ever Vail Commercial /Residential Structures Vail, Colorado We understand that the excavations for the proposed below -grade parking levels will be on the order of 30 to 40 feet in depth. Present plans call for a soil nail and "shotcrete" - type system to provide temporary support for that excavation that will largely preserve the exposed soils in their native condition. This temporary shoring system is being designed by the Contractor. Many excavations will be in close proximity to existing buildings, utility lines and other installations. The Contractor should take care during excavations not to compromise the bearing or lateral support for the existing structures or other improvements. 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 particularly CFR 29 Part 1926, OSHA Standards - Excavations, adopted March 5, 1990. Project excavations and shoring should be observed regularly by the Geotechnical Engineer throughout construction operations. 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 Vail Resorts Development Company, and is not assuming responsibility for construction site safety or the Contractor's activities. I ]*r Job No. 07 -6027 GROUND Engineering Consultants, Inc. Page 34 Ever Vail Commercial /Residential Structures Vail, Colorado UTILITY INSTALLATION Pipe Support The bearing capacity of alignment soils and bedrock appeared adequate, in general, for support of the proposed water line. The pipe + water are less dense than the soils which will be displaced for installation. Therefore, GROUND anticipates no significant pipe settlements in these materials where properly bedded. Excavation bottoms may expose soft, loose or otherwise deleterious materials, including debris. Firm materials may be disturbed by the excavation process. All such unsuitable materials should be excavated and replaced with properly compacted fill. Areas allowed to pond water will require excavation and replacement with properly compacted fill. The Contractor should take particular care to ensure adequate support near pipe joints which are less tolerant of extensional strains. Where thrust blocks are needed, they may be designed for an allowable passive soil pressure of 250 psf per foot of imbedment may be used, to a maximum of 2,500 psf. Sliding friction at the bottom of thrust blocks may be taken as 0.30 times the vertical dead load. Pipe Installation Recommendations regarding utility trench excavation are provided in the Excavation Considerations section of this report. On -site soils excavated from trenches are suitable, in general, for use as trench backfill. Backfill soils should be free of vegetation, debris, trash and other deleterious materials. Cobbles and non - expansive rock fragments coarser than 4 inches in maximum dimension should not be incorporated into trench backfills. Fragments of excavated claystone coarser than 3 inches in maximum dimension should not be incorporated into trench backfills. Pipe bedding materials, placement and compaction should meet the specifications of the pipe manufacturer and applicable municipal standards. The Contractor should not anticipate that significant volumes of excavated, on -site materials will be suitable for use where relatively free - draining bedding materials are called for. Materials proposed for use as pipe bedding should be tested for suitability prior to use. Imported materials should be tested and approved by the Geotechnical Engineer prior to transport to the site. Bedding should be brought up uniformly on both sides of the pipe to reduce differential loadings. CJ Job No. 07 -6027 GROUND Engineering Consultants, Inc. Page 35 Ever Vail Commercial /Residential Structures Vail, Colorado Trench backfill materials above the pipe bedding zone should be conditioned to a uniform moisture content, placed in uniform lifts not exceeding 6 inches in loose thickness, and properly compacted. Recommendations for fill placement and compaction are presented in the Project Earthworks section of this report. The Contractor should take adequate measures to achieve adequate compaction in the utility trench backfills, particularly in the lower portions of the excavations. Some settlement of trench backfill materials should be anticipated, even where materials are placed and compacted correctly. The Contractor also should take particular care to achieve and maintain adequate compaction of the backfill soils around manholes, valve risers and other vertical pipeline elements where greater settlements commonly are observed. Use of "controlled low strength material" (CLSM), i.e., a lean, sand - cement slurry, `Plowable fill," or similar material should be considered in lieu of compacted soil backfill for areas with low tolerances for surface settlements. Placement of fowable fill in the lower portions of the excavations and around risers, etc., likely will yield a superior backfill, although at an increased cost. We assume that surface drainage will direct water away from trench alignments. Nevertheless, non -woven filter fabric (e.g., Mirafi 14ON, or the equivalent) should be placed around the granular bedding materials to reduce migration of fines into the bedding which can result in severe, local settlements. Where this protection is not provided, severe settlements can result, even where backfill soils have be compacted properly. Where this protection is not provided, severe settlements can result as much as several months or years after construction is completed, even where backfill soils have be compacted properly. Development of site grading plans should consider the subsurface transfer of water in utility trenches and the pipe bedding. Sandy pipe bedding materials can function as efficient conduits for re- distribution of natural and applied waters in the subsurface. Cut- off walls in utility trenches or other water - stopping measures should be implemented to reduce the rates and volumes of water transmitted along utility alignments and toward buildings, pavements and other structures where excessive wetting of the underlying soils will be damaging. Incorporation of water cut -offs and /or outlet mechanisms for saturated bedding materials into development plans could be beneficial to the project. These measures also will reduce the risk of loss of fine- grained backfill soils into the bedding material with resultant surface settlement. 11*1 Job No. 07 -6027 GROUND Engineering Consultants, Inc. Page 36 Ever Vail Commercial /Residential Structures Vail, Colorado EXTERIOR FLATWORK Proper design, drainage, construction and maintenance of the areas between individual buildings and hardscape 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. Commonly, proper soil preparation in these areas receives little attention during overlot construction because they fall between the building and pavement areas, which typically are built with heavy equipment. Multiple sub- contractors, with light or hand equipment, often perform subsequent landscaping and hardscape installation. This results in necessary over - excavation and soil processing and compaction not being performed. Consequently, subgrade soil conditions commonly deviate significantly from recommended ranges. Therefore, GROUND recommends that the Contractor take particular care with regard to proper subgrade preparation in the immediate building exteriors. Positive surface drainage away from all pavements and flatwork should be included in project design. This is extremely important for satisfactory performance of project hardscaping. Proper drainage also should be maintained after completion of the project, and re- established as necessary. Exterior flatwork and other hardscaping placed on the soils encountered on -site likely will experience post - construction movements from consolidation of underlying or adjacent soils. Both vertical and lateral soil movements can be anticipated and distress to rigid hardscaping likely will result. The following measures will help to reduce damages to these improvements. 1) Shortly before installation, the subgrade soils beneath project sidewalks, paved entryways and patios, masonry planters and short, decorative walls, and other flatwork should be excavated and /or scarified to a depth of 8 to 12 inches. The excavated soil should be replaced as properly moisture - conditioned and compacted fill as outlined in the Project Earthworks section of this report, in order to reduce the magnitude of potential movements. 2) Prior to placement of flatwork, a proof roll should be performed to identify areas that exhibit instability and deflection. The deleterious soils in these areas should be removed and replaced with properly compacted fill. The Contractor should 0 Job No. 07 -6027 GROUND Engineering Consultants, Inc. Page 37 Ever Vail CommerciallResidential Structures Vail, Colorado take care to achieve and maintain compaction behind curbs to reduce differential sidewalk settlements. As in the case of pavements, passing a proof roll is an additional requirement to placing and compacting the subgrade fill soils within the recommended ranges of moisture content and relative compaction presented in the Project Earthworks section of this report. 3) Flatwork should be provided with control joints extending to an effective depth and spaced no more than 10 feet apart, both ways. Narrow flatwork, such as sidewalks, likely will require more closely spaced joints. 4) In no case should exterior flatwork extend to under any portion of the building where there is less than 2 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. Frost and Ice Considerations Nearly all soils other than relatively coarse, clean, granular materials are susceptible to loss of density if allowed to become saturated and exposed to freezing temperatures and repeated freeze — thaw cycling. The formation of ice in the underlying soils can result in heaving of pavements, flatwork and other hardscaping ( "frost heave ") in sustained cold weather up to 2 inches or more. This heaving can develop relatively rapidly. Much of this movement typically is recovered when the soils thaw, but due to loss of soil density, some degree of displacement commonly will remain. This can result even where the subgrade soils were prepared properly. Where hardscape movements are a design concern, e.g., at doorways, replacement of the subgrade soils with 3 or more feet of clean, coarse sand or gravel should be considered or supporting the element on foundations similar to the building and spanning over a void. Detailed recommendations in this regard can be provided upon request. It should be noted that where such open graded granular soils are placed, water can infiltrate and accumulate in the subsurface relatively easily, which can lead to increased settlement or heave from factors unrelated to ice formation. The relative risks from these soil conditions should be taken into consideration where frost heave is a concern. GROUND will be available to discuss these concerns upon request. Where soils supporting foundations or on which foundation will be placed are exposed to these conditions during construction — commonly due to water ponding in foundation Job No. 07 -6027 GROUND Engineering Consultants, Inc. Page 38 Ever Vail Commercial /Residential Structures 40 Vail, Colorado excavations — 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. The site soils include low plasticity silts as well as some clays and fine sands that due to their capillarity appear vulnerable to frost heave where an underlying source of water is present. Groundwater was not encountered to the depths explored, however. Therefore, if surface drainage is effective, the likelihood of movement of pavements, flatwork and other hardscaping is relatively low. However, if other source(s) of water develop and are not drained effectively, frost heave may develop. Job No. 07 -6027 GROUND Engineering Consultants, Inc. Page 39 Ever Vail Commercial /Residential Structures Vail, Colorado CLOSURE Geotechnical Review The poor performance of many pavements, foundations and subsurface structures has been directly attributed to inadequate geotechnical review and earthwork quality control. Therefore, project plans and specifications should be reviewed by the Geotechnical Engineer to evaluate whether they comply with the intent of the recommendations in this report. This review should be reported in writing. Project earthwork construction operations should be observed by the Geotechnical Engineer. All excavations should be observed by the Geotechnical Engineer prior to placement of fill or backfill soils, installation of shoring, or foundation construction. Placement of fill /backfill soils should be observed by the Geotechnical Engineer, and the soils tested. The geotechnical recommendations presented in this report are highly contingent upon observation and testing of project earthworks by representatives of GROUND. If another geotechnical consultant is selected to provide construction observation and quality control, 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. Limitations This report has been prepared Vail Resorts Development Company, as it pertains to design of the subject medical office /research facility as described herein. It may not contain sufficient information for other parties or other purposes. In addition, GROUND has assumed that project construction will commence by Spring, 2008. Changes in project plans or schedule should be brought to the attention of the 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 on Figure 1. Subsurface conditions were interpolated between and extrapolated beyond these locations. Findings were dependent on the limited amount of direct evidence obtained at the time of this geotechnical evaluation. Our recommendations were developed for site conditions as described above. Actual conditions exposed during construction may be anticipated to differ, somewhat, from those encountered during site exploration. If during construction, surface, soil, bedrock, or groundwater conditions appear to be at Job No. 07 -6027 GROUND Engineering Consultants, Inc. Page 40 Ever Vail Commercial /Residential Structures Vail, Colorado variance with those described herein, the Geotechnical Engineer should be advised at once, so that re- evaluation of the recommendations may be made in a timely manner. This report was prepared in accordance with generally accepted soil and foundation engineering practice in the Eagle County, Colorado, area, at the date of preparation. GROUND makes no other warranties, either express or implied, as to the professional data, opinions or recommendations contained herein. Sincerely, GROUND Engineering Consultants, Inc. ach t. Jean Reviewed by James li 68 B. v` s io Job No. 07 -6027 GROUND Engineering Consultants, Inc. Page 41 E E LLJ o 0 8 0 z 0 co) It 'o It % �7, `� ; 1 y i y 'F CL 'L It x V -�\ P, U) ( D T 6 3 CL m LL ( F ' v \� y� . \ ` \\\ i 1 �1 c C, I a 2 m CL \ �1. � _. �i a �• �� °� .• /• E cL CL m CL 4) CL E c 4) 0 � 1 \ C C \\ f c 6❑ x w Test Hole Test Hole Test Hole Test Hole Test Hole 1 2 3 4 5 Elev.8106 Elev.8112' Elev.8109 Elev.8116' Elev.8115' 8145 r 8135 8125 8115 m 0 8105 'HEAP 12/12 15/22/34 3" HEAP ] 31/12 50/4 15/17/28 100/6 1 I I R 8085 50/7 50/6 50/9 75/2 9/10/17 75/10 94/10 100/5 I 8075 8065 100/0 GROUP= ENOINEEl�IINe CONM)MINTS LOGS OF TEST HOLES JOB NO. 07 -6027 DRAWN BY: HS FIGURE: 2 APPROVED BY: JK CADFILE NAME: 6027LOG01.DWG Test Hole Test Hole Test Hole Test Hole Test Hole 6 7 8 9 10 Elev.8117' Elev.8117' Elev.8125' Elev.8119' Elev.8106 8145 8135 8125 3' HBAP 8115 N w o 8105 m N 8095 8075 I 8065 C HBAP 35/11/11 100/6 HBAP 6/12 6/12 16/11/11 33/22/35 ..�y�,(`Y J 50/10 100/4 20/2 10/12 30/12 25/12 77/12 75/9 75/9 HEAP 27/12 30/5 50/5 75/9 100/6 75/6 HBAP 75/10 75/7 unuum ENSINKURING CONSULTANTS LOGS OF TEST HOLES JOB NO. 07 -6027 DRAWN BY: HS FIGURE: 3 APPROVED BY: JK CADFILE NAME: 6027LOG02.DWG Test Hole Test Hole Test Hole Test Hole Test Hole 11 12 13 14 15 Elev.8117' Elev.8122' Elev.8126' Elev.8127' Elev.8123' 8145 r 8135 8125 8115 N i •� 0 w 8105 8095 8085 8075 8065 HEAP 17/12 50/5 75/4 70/5 HEAP 50/7 50/6 HEAP 11/13/11 50/8 100/7 HEAP 3' HEAP 36/12 7/9/8 11/16/5 100/12 120/9 75/1 ajwum ENGINNUMING CONSULTRNTS LOGS OF TEST HOLES JOB NO. 07 -6027 DRAWN BY: HS FIGURE: 4 APPROVED BY: JK CADFILE NAME: 6027LOG03.DW'G Test Hole Test Hole Test Hole Test Hole Test Hole 16 17 18 19 20 Elev.8119 Elev.8116' Elev.8126 Elev.8128' Elev.8131' 8145 8135 1 45/1 PCCP 6" PCCP 3 " HEAP 8125 LOGS OF TEST HOLES JOB NO. 07 -6027 DRAWN BY: HS FIGURE: 5 APPROVED BY: JK D n0� su D ■ r a D.g '3OD W ■ q;a "4D1 3" HBAP a 50/6 V 4. as -� �. 20 /12 q ' q. n A 9 ■ 50/11 f V7, q.a An I grgu a '. p �� ' AA ■ 1 q "ate 1 ' sa a ■ p W■ 50/5 . 7 J 1 8 0 95 9 9 " S 50/4 90/8 8085 8075 8065 C 50/5 100/6 49/35/19 50/2 GROU ENBINEERIMe CONSIMTRNTS LOGS OF TEST HOLES JOB NO. 07 -6027 DRAWN BY: HS FIGURE: 5 APPROVED BY: JK CADFILE NAME: 6027LOG04.DWG Test Hole Test Hole Test Hole 21 22 23 Elev.8105' Elev.8106 Elev.8138' 8145 r 8135 Test Hole Test Hole 24 25 Elev.8134' Elev.813U 717/7 11/22/25 8125 8115 m w 0 8105 r N 8095 8085 8075 8065 r 36/12 19/27/20 50/5 9/12 16/12 12/12 33/12 32/12 70/10 26/31/38 50/6 GROUM IFNGINEElIING CONSLIt.T17NTS LOGS OF TEST HOLES JOB NO. 07 -6027 DRAWN BY: HS FIGURE: 6 APPROVED BY: A CADFILE NAME: 6027LOG05.DWG Test Hole Test Hole Test Hole Test Hole B1 B2 B3 B4 Elev.8120' Elev.8106 Elev.8113' Elev.8113' 8145 l 8135 8125 8115 w N 0 8105 60/12 68/12 80/5 'HEAP ABC 7112 4"HBAP ] 12/12 6/12 8095 8085 8075 8065 Wl* 12/36/34 75/5 unaurm KNGINEE/IINi CONSULTl4NTi LOGS OF TEST HOLES JOB NO. 07 -6027 DRAWN BY: HS FIGURE: 7 APPROVED BY: JK CADFILE NAME: 6027LOG06.DWG JOB NO. 07 -6027 DRAWN BY: HS FIGURE: 8 APPROVED BY: JK CADFILE NAME: 6027LOG07.DWG Test Hole Test Hole Test Hole Test Hole P1 P2 P3 P4 Elev.8107' Elev.8119 EIev.8130' Elev.814Z 8145 13/16/14 8135 50/6 14/12/11 8125 10/12/18 8115 9/20/17 14/16/20 a� w 0 8105 417/8 65/10 100/8 8095 80/6 8085 8075 8085 8190UNE ENGINEERING CONSULTRI LOGS OF TEST HOLES JOB NO. 07 -6027 DRAWN BY: HS FIGURE: 8 APPROVED BY: JK CADFILE NAME: 6027LOG07.DWG LEGEND: Topsoil ® Hot Bituminous Asphalt Pavement (HEAP) ® Portland Cement Concrete Pavement (PCCP) Base Course Fill: Ranged from silty sands with gravel to silty to clayey gravels; slightly moist to moist, slightly to moderately plastic, loose to medium dense, and brown to pale gray in color. Although not identified in the test holes, based on prior construction on the site and adjacent areas, construction debris likely is present in the fill soils locally. Sand: Fine to coarse, and silty to clayey with gravel commonly. Scattered cobbles and boulders were noted locally; moist to wet, low plastic, loose to medium dense, and brown to gray in color. Sand and Gravel: Ranged from silty to clayey to gravelly sands to silty to clayey gravels, cobbles and boulders were common throughout the alluvial section, but particularly in the lower materials; fine to coarse grained, dry to wet, non - plastic to moderately plastic, locally loose to moderately dense to very dense, and pale gray to brown -gray in color. k ] Drive sample, 2 -inch I.D. California liner sample k ; Small disturbed sample 23/12 Drive sample blow count, indicates 23 blows of a 140 -pound hammer falling 30 inches were required to drive the sampler 12 inches. 0 Depth to water level and number of days after drilling that measurement was taken. Rig Refusal NOTES: 1) Test holes were drilled on 06/25 -30/07 and 07/23/31/07 with 4 -inch diameter continuous flight power augers. 2) Locations of the test holes were measured approximately by pacing from features shown on the site plan provided. 3) Elevations of the test holes were approximated from Client provided site map and the logs of the test holes are drawn to elevation. 4) The test hole locations and elevations should be considered accurate only to the degree implied by the method used. 5) The lines between materials shown on the test hole logs represent the approximate boundaries between material types and the transitions may be gradual. 6) Groundwater level readings shown on the logs were made at the time and under the conditions indicated. Fluctuations in the water level may occur with time. The material descriptions on this legend are for general classification purposes only. See the full text of this report for descriptions of the site materials and related recommendations. LEGEND AND NOTES JOB NO. 07 -6027 DRAWN BY: HS FIGURE: 9 APPROVED BY: JK CADFILE NAME: 6027LEG.DVNG E � 41 E `j r ltd 'x � CL I W M ON 0 W II 11, r Lu zo S , w ci 1 = z 0 S2 a c6 w O Z M 0 "' W M 3: ' w S 0 a =) -J � 0 V* W w z I N W 2< w c6 m LU W cn\ w awlRmw V N I N X li e o E 0 4) 3. 11 � � ` \. m m m a vv io �. o C x 0 0 cR o c: L cc i j� k o a \ ``4 on _! K m \ ° r Q E �� _ ^•F. _ 1 5 i n ��` � I •\ � � �� i t 1 � � E � E th LL 0 C6 CL CL m to ` ° ! o c O CD to N i L • a X o IL t. 4mo 1 m n . r o m rx V L CD \ C ♦\ `� ` U E r U m m m N N , m d wW, 0 r: \m 41 \ , ` •� \ a J b \ _l�J� d \ "I7: \ ..- L am. � -- '•\,. r ` e / \ I I M Win N t CC UJ ul o LU k LL w `x 1 N0 80 5 cl C �Y NIL n e i 1 i E c0 X E d a n x O m � o m � m \ c � � m 1 fq t� 8 n a m CL cc , , , a m A W a X W m J C ` w a p 3 m c K a L v m a y � { aa p i g m V V V ' C C C �❑ X ` \ N c H �3 e / \ I I M Win N t CC UJ ul o LU k LL w `x 1 N0 80 5 cl C �Y NIL n e i 1 i E c0 X E d a n x O m � o m � m \ c � � m 1 fq t� 8 n a m CL cc , , , a m A W a X W m J C ` w a p 3 m c K a L v m a y � { aa p i g m V V V ' C C C �❑ X in 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. MIRIFI 140 OR EQUAL 6" MIN 12" MIN 4 INCH DIAMETER PERFORATED DRAIN PIPE. 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 ® THE UNDERDRAIN SYSTEM MUST BE TESTED BY THE CONTRACTOR AFTER INSTALLATION AND BACKFILLING TO VERIFY THAT IT FUNCTIONS PROPERLY. NOTE: THE HIGHEST POINT OF DRAIN PIPE FLOW LINE SHOULD BE AT LEAST 4 INCHES BELOW THE BOTTOM OF THE STRUCTURAL FILL AND SLOPE DOWNWARD TO A POSITIVE GRAVITY OUTLET OR TO WHERE WATER CAN BE REMOVED BY PUMPING. PROVIDE POSITIVE SLIP JOINT BETWEEN SLAB AND WALL FLOOR SLAB MINIMUM GRANULAR LAYER almal"m ENGINKSMINi CONSULTRNTS TYPICAL UNDERDRAIN DETAIL JOB NO.: 07 -6027 DRAWN BY: HS FIGURE: 13 APPROVED BY: BHR CADFILE NAME: 6027DRAIN.DWG :7 d CL _V Z F-' a r N Q V m NN CO Q U . c L Q Q ti CD C (G C tD C w zN C LO 0 �8 m z OZ a � W z z W d CL _V Z F-' a r N Q V m NN CO Q U . c L Q Q ti CD C (G C tD C w C CO C LO 0 z 0 U d C C C C l0 - M V C V C C C C C C 0 0 0 0 0 0 0 0 n d m N N N J W W W W 3 v c � W _ _ is c W U U W W w C n .. W `Q1 OD . CD M O , m 2 0 C N -' d1 m J A W ( A O d (G Po- o OZZ J U1 � OD tD cD � � (7► � a .1 C b GW O to ` W Oo N e� w � 1 � A � V W -+ 1X• (0 _� C Cn CO • A o � � pt C) a 4�k CL Npd 00 A C 00 r 09 N N — co N W _r .f� '. � py r v 0 A 0 m L" co A cn G� cn G� 0 ca n n m K 0.0 cn n cn n Ig 0 O :o Z D m p m m 'Z C w CL ' p a < M G -� rn V/ C 3 D X O In 5 O O m �i X m c D W N m z i m z E ll m E ll n 0 z m c z a ts LA lJ E- C N 3 D 0 I n la Im 0 0 m A X m C -1 N z� E ll m W m 0 F m N z N c z In a 4 Ul z _ CO - CO OD OD -1 - I V C7) O ) 0 0 O y 3 r � O U .a Cn ..+ O A W CA (n .► O � A A A 0 ...► Cn A W —a A N � O�� � r O 7 ozz CO W A -I 0 O N A C)t N � N ~ N P W �� c O tD -1 A OD -I W c0 0:0 W V O C d A � z N i Cn i A O' 7 74 CA) W w -� co w w Y C W `-° a I d A N V A CA W OD O GO 0) CO � ems 3 D. N 0 im t0 -+ O N V -• A r CO v W 0 CA) CO A- 0) -r . N CA) N OD W 'N N p 7 om rn OD : A 0 W N ' -� CO CO - OD ' Co w OD ; CA) pe 3 c W o A C„ = Z "0 O C7 CD o C„ 0 A Z V, cm O � g �► p d r 3 CD =s y 0 C 0 n Cn cn U) : (n U) U) . Cl) Cl) cn 0 0 cn Cn Cn m n` (� ' (� m n (� cD . (n m n` n n 01 � p) p) pi � Z �I 01 2) C1 Z , = CD C (D = m ,CD Z p Z :CD m :m p D r Cl) (� D m; D G7 p r p D D N o o '� -� :o ? : o :� o R o. .� .o C) m m � o d =r °D =r CD G7 z CD m UUL CD N 3 D 0 I n la Im 0 0 m A X m C -1 N z� E ll m W m 0 F m N z N c z In a 4 Ul C•. L�*] N a O r rn D O O rn 4 X CO) r N zo E ll ..� m a '° WHO r � rn N z in c �a a z in f ° O N N N N N N N N -► -+ -� -' Z C O r v c 00 W W CJ� (A (D O (D OD CT1 (D (O O 2 ,W,� 0 ._► O 7 O .14 W �D N (A CM V 0 V (D 0 -4 N (D C; N o 2a . tD C2 CJ1 W CJ1 W CD OD GJ GJ W O W CT V (p C i 41 P W v z 3 W aD v �4 iD C O .P p� G) c o co -4 A W a , Cat e � (p d f w p la p A N (D Cn CA O O O v' CA 7 7 f. d Nca F. V V V , A OD W N V N W V N CJ1 W V W O (P °� N �. N ? 00 N N V C V OD e 3 C IP 1 00 ' OD 00 V Z V Oo ; Z : N ` Z Z Cn CT O (D ': A Cdr a 3 f - ^^ YJ C/) - - ± M � N •I C CD Co T C7 n n < (n (n < n (A (A (� (n (n Lo n N o n tD '.y D n D .� (n .� °' `D Z _ :� G7 z Z z .o� .(n °' `cn :Z O O D O D'? �. �. (n D (n D a N m a�—i .� ,@ m :Z m — ;? 'D '� (D — N — .0 .� .� � — ULJ Li N a O r rn D O O rn 4 X CO) r N zo E ll ..� m a '° WHO r � rn N z in c �a a z in N LLI N z ` W ` Q r J i N o J O Le �zm W F— W �3 g Z , W 0 } Q N m cv `O vg.� co ) N . 2 w c Q v ch co l- , ry � o N . N J CD N m o \ 0- r zy c y ° °' m CL I�11� 0 N O O O z a 0 I. 2 a C 2 _2 L 7 � � Z` c o mo m °. 0 z c c t6 z2V N CL I�11� 0 N O O O z a 0 I. 2 a C 2 _2 L 7 � *1 F�- Z m J 3 vi Z O U z Z W 6 z W a W m Z H Z O V vi J N W U) W H 0 9 m g LL O a 2 U) V, W J H u C7 APPENDIX A Geophysical Study by Zonge Geosciences, Inc. Zt)i1C {. Zonge Geosciences, Inc. 1990 S. Garrison Street Suite 82 Lakewood, CO 80227 Phone: (720) 962 -4444 Fax: 720- 962-0417 zonQeooloLa�zonoe.com August 24, 2007 Brian Reck Ground Engineering Consultants 7393 Dahlia Street Commerce City, CO 80022 Subject: Geophysical Investigations Report — Ever Vail Project. Vail, Colorado: Ground Engineering Project No. 07 -6027 Dear Mr. Reck, This letter report presents results from the geophysical investigation conducted at the Ever Vail Project site. The investigation was located just west of the town of Vail, Colorado, between South Frontage Road and I -70 as shown on Figures 1 and 2. Zonge Geosciences, Inc. (Zonge) performed the geophysical investigation under subcontract to Ground Engineering Consultants (Ground). Field data were acquired on July 16, 2007. Two sites were selected by Ground personnel where the objectives of the geophysical investigation are twofold: 1) to map the top -of- bedrock and determine thickness and lateral variability of unconsolidated soil deposits; and, 2) to obtain seismic velocities within the bedrock, if encountered. These seismic data were to be correlated with the mechanical strength and rippability of such materials to aid in the excavation planning for this project site. As we understand it, the geophysical data will be used to evaluate subsurface conditions and aid in the planning for construction of a new parking garage and gondola base at the sites. Based on the geologic setting and the site conditions outlined by Ground, Zonge determined a combined seismic survey approach using two - dimensional (2D) refraction tomography and one - dimensional (1D) refraction microtremor (ReMi) soundings would best achieve the project objectives. This report summarizes data acquisition parameters and field methods for the investigation, and also includes brief sections on data processing (1 D and 2D), and results /interpretations. SITE DESCRIPTION The area of investigation is located just west of Vail, Colorado, and just south of 1 -70 (see Figure 1). The seismic lines were placed in two separate parking lots, on pavement, between I -70 to the north and a frontage road to the south (see Figure 2). Holes were drilled in the pavement using an impact hammer drill for the placement of each geophone. This area had extremely heavy traffic, including heavy cargo trucks on the highway and frontage road that caused a significant amount of vibrational noise. Boring logs provided by Ground indicate the overburden soils are fairly uniform and are generally comprised of sands and gravels. Bedrock was not encountered in any of the borings, however, SPT blow counts increase in depth from as low as 8 near the ground surface to refusal (>50/12 ") at depths below - 10 feet. Water was encountered in most of the borings at depth ranging from 10 to 28 feet below the ground surface. 0 �v a y G �.d c l 7 ) 1 A 0 DATA ACQUISITION Seismic refraction and ReMi data were acquired using a Geometrics R24 seismograph. This system utilizes a state of the art, stand -alone 24 -bit seismograph. Analog data from the geophones are collected in the R24 seismograph where the data are anti -alias filtered, converted to a digital signal, and then recorded on an internal hard drive or removable disk. The RS24 module has a 24- channel capacity. Twenty -four receivers (geophones) were placed on the ground along each line. The receivers were 50 -Hz vertical component geophones. The same instrumentation and line geometry were used for both the refraction and ReMi data acquisition. Refraction: A total of two refraction lines were acquired at pre - selected sites for this investigation. Line 1 was oriented east -west and Line 2 was oriented north -south as seen in Figure 2, with channel 1 on the west and north ends respectively. Thus the tomograms are viewed as if the reader is "looking north" at Line 1 and "looking east" at Line 2. Geophone spacing along each line was 10 feet. Compressional -wave (P -wave) seismic energy was created with a source that consisted of an elastic wave generator (EWG). The EWG used for this project is a truck mounted, hydraulically controlled, 100 pound weight that is lifted and then accelerated onto a metal plate using a large rubber strap to maximize acceleration and the resultant amount of energy imparted into the ground. A 16 -pound sledgehammer striking an aluminum plate was also used in shot locations that couldn't be safely accessed with the EWG. Up to a maximum of 20 EWG or hammer blows were used to transmit seismic energy across the line of 24 geophones with the maximum number being required for the 2 off -end shot points or during exceptionally noisy periods of the day. Source points were located as shown on the inset illustration; `off -end' shot points were located 50 and 100 feet beyond each end of Line 1 and 40 feet beyond each end of Line 2. This made for a total of 13 shot points for Line 1. Line 2 had 11 shot points due to spatial limitations of the survey location (survey extended from the I -70 barricade into the east- bound lane of South Frontage Road). Shot records were acquired in SEG -2 format, using a 0.25 millisecond (msec) sample rate and 500 msec ('/2 second) record length. ReMi: The refraction microtremor (ReMi) method uses the same instrumentation and field layout as the refraction survey. However, there are no predefined source points required for this seismic method. The ReMi method uses ambient noise, or vibrational energy, that exists at a site. The existing natural vibrations were enhanced by Zonge personnel with the use of the EWG system, Geophone 1 TB -1 Geophone 24 1 I x 6 oxo 6 oxe 0 exe 0 oxo 0 exe 0 exe 0 oxo a •x 230 ft X - Source Point o - Geoplhone ReMi: The refraction microtremor (ReMi) method uses the same instrumentation and field layout as the refraction survey. However, there are no predefined source points required for this seismic method. The ReMi method uses ambient noise, or vibrational energy, that exists at a site. The existing natural vibrations were enhanced by Zonge personnel with the use of the EWG system, random sledge hammer blows, driving a vehicle along the seismic line, walking up and down the line, and wind noise. These small- strain vibrations cause surface wave energy to propagate across the site and be recorded for the ReMi method. At least ten, unfiltered, 30- second ambient vibrational energy records (`noise' records) were recorded for each line using a 2 msec sample rate. DATA PROCESSSING Refraction: Refraction tomography is a modern extension of the seismic refraction method, and has been used to study the interior of the earth from scales of miles to tens of feet. The method was introduced in the 1980's, and uses a similar mathematical approach as the CAT scans (computed automated tomography) used for medical imaging. Tomography is the process of reconstructing spatial variations of a physical property (in this case compressional -wave velocity) from spatially distributed measurements that depend on that property (travel time). It follows that tomographic surveys require the measurement of travel times from large numbers of paths, or "ray- paths" through the media being imaged; in this case, soil and rock materials below the refraction spreads. For this project the tomographic inversions were performed using a simulated annealing algorithm. Due to the noisy nature of this site, and the resulting noise in the data collected on these two lines, a low -pass filter was utilized to remove noise and better identify the first arrivals of refracted energy along each shot record. First -break picks were then made on all of the shot records acquired along each line. Travel times, along with source and receiver positions and elevations were formatted into files and input to the tomography software. Tomographic analysis was carried out using SeisOpt @2DTM (© Optim, Inc., 2006), a commercially available refraction tomography package produced by Optim, LLC (Version 4.0). A two - dimensional cross - section with velocity information at each subsurface point is produced. P -wave velocities can be correlated to the material type. Simulated annealing is a Monte -Carlo estimation process that derives arrival times (P- and/or S- wave) and a velocity model from the data ( Pullammanappallil and Louie, 1993; Pullammanappallil and Louie, 1994). The algorithm works by randomly perturbing an arbitrary starting model until the synthetic travel times computed through it match the travel times picked from the data. Unlike linear, iterative inversions, simulated annealing optimization will find the global solution while avoiding local error minimums. The method is insensitive to the starting velocity model, removing the interpreter bias that may be involved in a prospect or project. The fact that SeisOpt @2D makes no assumption about subsurface velocity gradients makes the method ideal for imaging laterally complex subsurface geology. Refraction tomography allows reconstruction of both vertical and lateral velocity variations. The ray -path coverage for all rays traveling through the model is analyzed to determine coverage. A ray is a region in the model that has the highest contribution to the first arrival time. In this survey, the rays probed 20 to 80 feet below the ground surface. The depth of investigation for any refraction survey is dependent on the receiver line length, and the velocity distribution of the subsurface materials, and the offset shot distance. ReMi: The ReMi method calculates the shear -wave velocity (Vs) of layers and the respective depths to interfaces beneath the refraction line as described by Louie (2001). The ReMi method is primarily used to calculate shear velocity versus depth at a point (1D) to satisfy building code requirements (International Building Code — IBC). The analysis computes the average shear - wave velocity to a depth of 100 -feet (30 m) as described in Section 1615.1.1 of IBC 2000; that is the "Vs100 ". ReMi data were collected for both refraction lines at this site. The `noise' records collected at this site were processed using the SeisOpt® ReMiTM software (© Optim LLC, 2005) (Louie, 2001). The ReMi technique is based on two fundamental concepts. The first is that common seismic - refraction recording equipment can effectively record surface waves at frequencies as low as 2 Hz. The second idea is that a simple, two - dimensional slowness- frequency (p -f) transform of a microtremor record can separate Rayleigh surface waves from other seismic arrivals. This separation allows recognition of the true phase velocity and discriminates against energy propagating in other modes without dispersion. The advantages of ReMi from a seismic surveying point of view are several, including the following: It requires only standard refraction equipment; it requires no triggered source of wave energy; and, it will work best in seismically noisy urban settings. Traffic, construction, and wind responses of trees, buildings, and utility standards provide the surface wave energy ( "source ") for the recordings. There are three processing steps to derive the Vs profiles: Step 1 : Create a velocity spectrum (p -f image) from the noise data. The distinctive slope of dispersive waves is an advantage of the p -f analysis; body waves and airwaves cannot have such a slope. Even if most of the energy in a seismic record is a phase other than Rayleigh waves, the p -f analysis will identify the dispersion of the surface waves. Step 2 : Rayleigh -wave dispersion picking - Picking is done along a lowest p -f envelope bounding the dispersed energy appearing on the p -f image. The picks thus discriminate against higher apparent velocities present because `noise' impacts the linear array from all directions. Picking a surface -wave dispersion curve along an envelope of the lowest phase velocities at each frequency has a further desirable effect. Because higher -mode Rayleigh waves have phase velocities above those of the fundamental mode, the refraction microtremor technique preferentially yields the fundamental -mode velocities. Step 3 : Shear wave velocity modeling - The ReMi method interactively forward- models the normal -mode dispersion data picked from the p -f images with a code adapted from Saito (1979, 1988) by Yuehua Zeng(1992). This code produces results identical to those of the forward - modeling codes used by Iwata et al. (1998), and by Xia et al. (1999) within their inversion procedure. The modeling iterates on phase velocity at each period (frequency), reports when a solution has not been found within the iteration parameters. The analysis approach and the propagation properties of surface waves allow velocity reversals (low Vs layers at depth) to be modeled successfully. 0 RESULTS / INTERPRETATIONS Refraction: The 2D refraction results are presented as seismic sections (i.e., distance vs. depth and velocity distribution) from the tomography analysis on Figures 3 and 4. Depth, distance and velocity scales are the same for both lines. Interpreted depth to weathered bedrock and depth to competent bedrock are indicated on the tomograms with dotted and dashed lines respectively. For actual depth to bedrock, Ground boring logs should be consulted. Depth to bedrock, as interpreted by the refraction tomography, is based on a velocity threshold of about 5,500 ft/s (i.e., mid -green color). 5,500 ft/s is a reasonable value for fractured and weathered granites. Possibly, low densities and the potential for weathering at the soil/bedrock interface can be seen in the 2D sections as the variable section of greens and light blues above the faster velocity regions indicated by yellow and red. Interpretation of the P -wave refraction velocity sections obtained indicate three velocity layers: low- velocity materials interpreted as unsaturated and/or saturated, unconsolidated alluvium (i.e., 1,500 -5,500 ft/s), generally shaded in blue or "cool' colors; moderate - velocity materials (i.e.,5,500 -9,000 ft/sec) interpreted as weathered and/or fractured granite shaded in green to light yellow; and, relatively high - velocity materials interpreted as competent bedrock ( >9,000 ft/s) shaded yellow and red or "hot' colors. The interpreted depth to bedrock line (dotted line) shown on the figures is only based on velocity trends in the tomograms. Both 2D seismic profiles generally indicate a sharp boundary between the interpreted overburden and bedrock. Figure 4 shows vertical bands of 4,000 ft/s (light blue) surrounded by lower velocity regions (darker blue). These vertical bands of slightly higher velocity indicate the location of the calculated ray paths in the final model, and the surrounding slower regions had no calculated ray path coverage and are therefore not well constrained. These are believed to be artifacts of the gridding process, and these slower regions should most likely be assigned velocities closer to that of the light blue vertical bands which are approximately 4,000 ft/s. These vertical bands of ray path coverage beneath each shot point are probably a result of highly uniform velocities in the upper 20 -30 feet of overburden materials. This homogeneity would have initially prevented the refraction of energy, causing ray paths to be vertical prior to encountering velocity gradients at depth and refracting back towards the surface. Several inversions were done on this set of data to ensure that this was the best fit model for Line 2, and these vertical ray paths were resolved in all inversion results. Figure 4 also indicates two regions of lower velocity material at depth between stations 0 -50 feet and between stations 150 -200 feet. These could be regions of more extensively fractured and /or weathered rock, or they could indicate the presence of thicker overburden materials at these locations. The dotted line that indicates the interpreted top of weathered rock could have followed the lower interface of blues and greens below these low- velocity regions, and this uncertainty in interpretation is indicated by the question marks placed along the dotted interpretation line. Vertical variations in material type are observed in the 1D (ReMi) S -wave velocity distributions as well as in the 2D (tomography) P -wave velocity sections beneath each line. That is, the seismic results suggest a thick layer of potentially weathered and/or fractured bedrock (i.e., soil over weathered low- velocity bedrock). The calculated velocities at depth are within the typical range for granite bedrock. REMI: ReMi soundings (i.e., 1D S -wave velocity values versus depth) were computed beneath both lines. The 1D sounding data are derived by averaging the ambient noise across the 230 -foot receiver array and represent the bulk properties of the soil and/or rock beneath the `entire' array. ReMi calculations are based on determining the lower -bound for the surface wave dispersion which provides a conservative (i.e., lowest possible) shear -wave velocity for each layer modeled in the 1D result. The resultant ReMi models are presented on Figures 5a through 6a. The ReMi results indicate a sequence of overburden deposits with s -wave velocity ranging between about 360 and 2,000 ft/sec. These observed s -wave velocities are in a reasonable range for unconsolidated alluvial deposits. The resultant model for line 1 a region of higher velocity layers between 7 and 15 feet deep, but the two models generally indicate an increase in s -wave velocity with depth. Trends in the s -wave velocities that are interpreted to indicate bedrock are seen as the sudden increase in velocity at depths of approximately 30 feet for both ReMi models. There is a second increase in s -wave velocities seen on both ReMi models at a depth of approximately 60 feet. This is interpreted to indicate the interface between weathered and competent bedrock. This is in agreement with the interpreted top of weathered bedrock and the interpreted top of competent rock based on the p -wave tomography results. Note that the velocities and layer thicknesses derived by the ReMi method are averaged over the 230 -foot seismic line. Three observations provide confidence in the geophysical results: 1) There is good correlation with results computed using both refraction tomography (P -wave) and ReMi (S -wave) seismic methods; 2) Multiple tomographic inversions were performed and yielded repeatable results and consistent trends in velocity distributions that support the provided interpretation; 3) The seismic data quality ranged from fair to good, and was improved by the use of selective filtering in the frequency domain. If you have any questions regarding the field procedures, seismic analysis techniques, or the 2D refraction tomography or 1D ReMi results and interpretations presented herein, please do not hesitate to contact us. We appreciate working with you and look forward to providing you with geophysical services in the future. Respectfully Submitted, Justin Ringers Geophysicist Zonge Geosciences, Inc. Phil Sirles Managing Geophysicist Zonge Geosciences, Inc. u REFERENCES Iwata, T., Kawase, H., Satoh, T., Kakehi, Y., Irikura, K., Louie, J. N., Abbott, R. E., and Anderson, J. G., 1998, Array microtremor measurements at Reno, Nevada, USA (abstract): Eos, Trans. Amer. Geophys. Union, v. 79, suppl. to no. 45, p. F578. Louie, J, N., 2001, Faster, Better: Shear -wave velocity to 100 meters depth from refraction microtremor arrays: Bulletin of the Seismological Society of America, v. 91, p. 347 -364. Pullammanappallil, S.K., and Louie, J.N., 1993, Inversion of seismic reflection traveltimes using a nonlinear optimization scheme: Geophysics, v. 58, p. 1607 -1620. Pullammanappallil, S.K., and Louie, J.N., 1994, A generalized simulated - annealing optimization for inversion of first arrival times: BSSA, v. 84, p. 1397 -1409. Saito, M., 1979, Computations of reflectivity and surface wave dispersion curves for layered media; I, Sound wave and SH wave: Butsuri - Tanko, v. 32, no. 5, p. 15 -26. Saito, M., 1988, Compound matrix method for the calculation of spheroidal oscillation of the Earth: Seismol. Res. Lett., v. 59, P. 29. Xia, J., Miller, R. D., and Park, C. B., 1999, Estimation of near - surface shear -wave velocity by inversion of Rayleigh wave: Geophysics, v. 64, p.691 -700. Elt U i y �A 4 Depth (ft) �o . 81- �d 0 N Nt co 000 Im t! 1° c W C oC O N ° o � 0 .� N r O O LO a co _O O CZ CD ° = V � m N O T +� N ° o 0 T F"n'► Q O d" g v /'�� W W C O p O O O O ° � � p `+•' �E � �� p L c L S p < N t O f O O O O O / N It CO 00 I 1 (ft) utdea U i y �A 4 C � 11 Depth (ft) o N � co 0 t � O 1 1 1 1 Ii 7 (n O C�� 1L O O O U N o° N 0 O LO CD _N d a O cz p m ` 0 0° j 0 0 W O O LO O d Q C 0 z O , 0 0 0 0 0 N d' w 00 1 i 1 1 • 1 (11) ytdaa 1 I A Shear -Wave Velocity, ft /s 0 1000 2000 3000 4000 5000 6000 7000 8000 .11 -1( -2( -3a -40 y -50 A -60 -70 -80 -90 -100 07114 Ground, Line 1: Vs Profile Figure 5a Figure 5a — Ever Vail Project, Line 1 ReMi model. v Figure 5b — Ever Vail Project, Line 1 ReMi supportive diagram. 0' 7 ]146=R()r; JD 1 i ReParr Shear -Wave Velocity, ft /s 0 500 1000 1500 2000 2500 3000 3500 4000 0 I -10 - - - - - - - - - -- -- -20 I -30 I - - -- - i -40 l -50 -60 - - - - - - -- -80 -J— - - - -- — - -- -- i -90 -- -- - - - -- i -100-- 07114 Ground, Line 2: Vs Profile Figure 6a Figure 6a — Ever Vail Project, Line 2 ReMi model. 07 14 Gli(I(_'n<'C) fi'eporr n* n r'lgure bb — Ever Vail Project, Line 2 ReMi supportive diagram. 10 D' 7 114 GRL)j V 16 Repurr