PRELIMINARY GEOTECHNICAL INVESTIGATION UCCS PARKING GARAGE STANTON STREET AND AUSTIN BLUFFS PARKWAY COLORADO SPRINGS, COLORADO

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1 PRELIMINARY GEOTECHNICAL INVESTIGATION UCCS PARKING GARAGE STANTON STREET AND AUSTIN BLUFFS PARKWAY COLORADO SPRINGS, COLORADO Prepared for: UNIVERSITY OF COLORADO AT COLORADO SPRINGS Facilities Services 1420 Austin Bluffs Parkway Colorado Springs, Colorado Attention: Mr. Gary Reynolds CTL T Project No. CS October 29, Mark Dabling Blvd Colorado Springs, Colorado Telephone: Fax:

2 TABLE OF CONTENTS SCOPE... 1 SUMMARY... 1 SITE CONDITIONS... 2 PROPOSED DEVELOPMENT... 4 SITE GEOLOGY... 4 FIELD INVESTIGATION... 5 SUBSURFACE CONDITIONS... 5 Existing Fill... 6 Natural Sand... 6 Bedrock... 6 Groundwater... 7 Seismicity... 7 SITE PREPARATIN AND UTILITIES... 7 CONSTRUCTION CONSIDERATIONS...10 Foundations...10 Slabs-on-Grade...10 Below-Grade Construction...11 Pavements...11 CONCRETE...12 SURFACE DRAINAGE...12 CONSTRUCTION OBSERVATIONS...12 GEOTECHNICAL RISK...13 LIMITATIONS...13 FIG. 1 LOCATION OF EXPLORATORY BORINGS FIG. 2 SUMMARY LOGS OF EXPLORATORY BORINGS APPENDIX A SWELL CONSOLIDATION TEST RESULTS TABLE A-1 SUMMARY OF LABORATORY TESTING UNIVERSITY OF COLORADO AT COLORADO SPRINGS

3 SCOPE This report presents the results of our Preliminary Geotechnical Investigation for the proposed Stanton Street Parking Garage to be constructed on the campus of the University of Colorado at Colorado Springs. This report includes a description of subsurface and groundwater conditions found in our borings and our opinions regarding the potential influence of these conditions on site development and structure construction. The report also includes preliminary geotechnical design and construction criteria for installation of buried utilities and site grading, and concepts for structure foundations, slabs-on-grade, and pavement sections. We believe this study was completed in general conformance with our proposal (CS ) dated September 12, No preliminary documents or construction plans were available for the proposed parking garage, at the time of this report. Our understanding of the project is based on the owner s verbal description of the location and type of proposed construction. The report was prepared based on conditions interpreted from conditions found in our exploratory borings, results of laboratory tests, engineering analysis, and our experience. As the project documents become more definitive, we should review the plans to formulate specific design and construction recommendations. Evaluation of the site for the possible presence of potentially hazardous materials (Environmental Site Assessment) is beyond the scope of this investigation. The following section summarizes our evaluation. A more complete description of the conditions found, our interpretations, and our recommendations are included in the report. SUMMARY 1. Depending on the actual size and location of the planned structure on the investigated parcel, a significant amount of site preparation and fill placement may be necessary to achieve the desired building pad elevation. 2. Subsurface conditions encountered in our exploratory borings drilled within the vicinity of the planned parking garage consisted of about 10 to over 25 feet of natural sand underlain by claystone or sandstone bedrock. A layer of existing fill material, 3 to 5 feet thick, was encountered at the UNIVERSITY OF COLORADO AT COLORADO SPRINGS 1

4 ground surface in two of the borings. Samples of the natural, very clayey sand, sandstone, and claystone exhibited low to moderate measured swell values when wetted. 3. At the time of drilling, groundwater was not encountered in the exploratory borings. When water levels were checked again two days after the completion of drilling operations, the borings were again found to be dry. 4. We believe grading and utility installation can be accomplished using conventional heavy-duty equipment. 5. To reduce the risk of excessive total and differential movements of potentially heavily-loaded foundation columns underlain by a possibly widely varying thickness of grading fill, natural soils and bedrock, we recommend the garage structure be planned considering a drilled pier foundation bottomed in the underlying bedrock. 6. New moisture conditioned and densely compacted grading fill and the onsite, natural soils will likely provide good support characteristics for lightly loaded, at-grade garage slabs. Slabs bearing on or near expansive claystone may experience movement and associated damage. Where claystone bedrock is present near the slab elevation, subexcavation of the claystone and replacement with moisture conditioned fill will likely be an appropriate method to mitigate the effects of the expansive materials. The risk of poor slab performance cannot be fully evaluated until plans and atgrade slab elevations are defined. 7. For planning purposes, pavement thicknesses for full-depth asphalt sections for access driveways to the garage in the range of 5 to 6 inches are anticipated. Concrete pavement, 5 to 6 inches thick, is expected in the lowest parking level. 8. Surface drainage should be designed for rapid runoff of water away from the proposed parking garage. Water should not be allowed to pond adjacent to the structure or over exterior slabs or pavements. SITE CONDITIONS The site of the proposed Stanton Street Parking Garage is located north of the intersection of Stanton Street and Mountain Lion Way on the campus of the University of Colorado at Colorado Springs. The parcel is situated on the face of a generally northwestfacing slope. The ground surface slopes downward to the northwest at grades estimated to be between about 10 and 15 percent, with locally near-vertical banks in the vicinity of what appears to be a detention basin the northwest portion of the property. A concrete vault that contains a storm drain outlet and manhole is situated along the southern edge UNIVERSITY OF COLORADO AT COLORADO SPRINGS 2

5 of the detention basin. What appears to be a fill wedge, pushed out from the west side of Stanton Street, is present in the northeast corner of the site. The western side of the fill wedge slopes downward to the west and northwest at a grade estimated to be about 20 to 25 percent. Two existing dirt roads are present along the northern edge of the site and in the central portion of the property. The site has apparently been used extensively in the past as a dumping area for a variety of materials. Scattered piles of dumped soil, construction debris (mostly concrete), telephone poles, and organic materials are present throughout much of the site. Overhead electric power lines form the western boundary of the parcel. Vegetation on the property consists of grasses, weeds, yucca, scrub oak, a few pine trees, and scattered deciduous bushes and trees. Some of the main features of the site are presented in Fig. 1. Photograph Nos. 1 and 2 depict the parcel in its current condition. Photo No. 1: Northeast corner of the site looking west from Stanton Street. UNIVERSITY OF COLORADO AT COLORADO SPRINGS 3

6 Photo No. 2: Southwest corner of the site looking north from Stanton Street. PROPOSED DEVELOPMENT We understand the proposed parking garage is in the preliminary conceptual planning stage. We anticipate the garage will be a cast-in-place and/or pre-cast concrete, multi-level structure. Concrete slabs are anticipated in the at-grade portions of the garage. Foundation loads are expected to be moderate to high. We anticipate paved driveways will provide access to the garage from Stanton Street. We understand an artificial playing surface is planned on the top level of the garage. SITE GEOLOGY Published geologic mapping ( Geologic Map of the Pikeview Quadrangle, El Paso County, Colorado, Jon P. Thorson, Christopher J. Carroll and Mathew L. Morgan, Colorado Geological Survey, 2001) indicates the site is underlain locally by alluvial deposits (Qfo). The upper member of the Laramie Formation (Klu) comprises the UNIVERSITY OF COLORADO AT COLORADO SPRINGS 4

7 underlying bedrock found beneath the near-surface soils. Conditions encountered in our borings generally confirm the mapping. Our borings and site observations suggest manmade fill of varying thickness has been placed at several locations across the site. FIELD INVESTIGATION Our field investigation included drilling five exploratory borings at the general location of the proposed garage, as outlined by personnel from UCCS. The approximate locations of the borings are shown in Fig. 1. Exiting topography and the presence of dumped materials across much of the site limited the possible locations where the borings could be drilled. The borings were advanced to depths of 25 to 35 feet using 4- inch diameter, continuous-flight auger and a truck-mounted drill rig. Drilling was observed by our field representative who logged the conditions found in the borings and obtained samples. Graphical logs of the conditions encountered in the borings, the results of field penetration resistance tests, and laboratory test data are presented in Fig. 2. Swell-consolidation test results are presented in Appendix A. Laboratory test data are summarized in Table A-1. Soil and bedrock samples obtained during this study were returned to our laboratory and visually classified. Laboratory testing was then assigned to representative samples. Testing included moisture content and dry density, swell-consolidation, sieve analysis, and water-soluble sulfate content tests. To evaluate potential heave, the swell test samples were wetted under applied pressures that approximated the overburden pressure (the weight of overlying soil). SUBSURFACE CONDITIONS Subsurface conditions encountered in our exploratory borings drilled within the vicinity of the planned parking garage consisted predominantly of natural sand underlain by claystone or sandstone bedrock. A layer of existing fill material was encountered at the ground surface in two of the borings. The pertinent engineering characteristics of the soils and bedrock encountered are discussed in the following paragraphs. UNIVERSITY OF COLORADO AT COLORADO SPRINGS 5

8 Existing Fill A layer of existing fill, about 3 to 5 feet thick, was encountered at the ground surface in two of the borings. The fill consisted of clayey sandy. The fill was loose to medium dense based on the results of field penetration resistance testing and our observations during drilling operations. The fill appeared to have been randomly dumped at the site over a significant period of time. What appears to be a fill wedge, estimated to be 10 to 15 feet thick, was observed along the eastern edge of the parcel, adjacent to Stanton Street. We doubt any documentation exists regarding the placement of the fill material, such as the results of field density testing, and so the fill must be considered to be of suspect quality and unsuitable to underlie the proposed structure, in its current condition. If free from deleterious substances, such as construction debris and organics, some of the material may be suitable for re-use as new fill within the planned development. The suitability of the existing fill for re-use should occur at the time of construction. Natural Sand About 10 to over 25 feet of natural, silty or clayey to very clayey sand was encountered at the ground surface or beneath the existing fill in each of the borings. Occasional layers of very sandy clay were found to be interbedded with the clayey to very clayey sand. The sand was medium dense to dense based on the results of field penetration resistance tests. A sample of the clayey sand tested in our laboratory exhibited a low measured swell value of 0.2 percent when wetted under estimated overburden pressure. Five samples of the sand contained 14 to 38 percent clay and siltsize particles (passing the No. 200 sieve). Our experience indicates the sands are typically non-expansive or exhibit low measured swell values when wetted. Bedrock Sandy to very sandy claystone bedrock and silty to clayey sandstone were found in four of the borings drilled at the site, beneath the natural soils, at depths of 10 to 19 feet below the existing ground surface. Claystone appeared to be the predominant bedrock material. Field penetration resistance test results indicated the bedrock was UNIVERSITY OF COLORADO AT COLORADO SPRINGS 6

9 medium hard to very hard. Three samples of the claystone tested in our laboratory exhibited measured swell values of 0.2 to 1.8 percent when wetted under overburden pressure, which is indicative of slightly to moderately expansive material. A sample of the clayey sandstone exhibited a measured swell of 0.1 percent when wetted. The sandstone is typically non-expansive or exhibits low measured swell values when wetted. Groundwater At the time of drilling, groundwater was not encountered in the exploratory borings. When water levels were checked again two days after the completion of drilling operations, the borings were again found to be dry. Our experience indicates groundwater can occur in different forms below this site. Water can be found in the fissures within the bedrock. A perched groundwater table can also form at the interface between the overlying granular materials and underlying bedrock. The occurrence of groundwater, the volume, and elevation will fluctuate in response to seasonal precipitation variations, surface drainage, and landscaping irrigation. Seismicity This area, like most of central Colorado, is subject to a degree of seismic activity. We believe the soils and bedrock on the site classify as Site Class C (dense soil and soft rock) according to the 2009 International Building Code (2009 IBC). A geophysical study is required to evaluate the shear wave velocity (V100) profile at the site to potentially allow for an upgrade to Site Class B. Our firm can provide a site-specific geophysical seismic study using the ReMi micro-tremor, surface method, if desired. SITE PREPARATION AND UTILITIES No grading plans were available for our review during the preparation of this study. Based on the existing site topography, we anticipate a significant amount of site preparation work will be needed to achieve the desired building pad elevation and grades within the any access driveways. The amount and complexity of the site preparation work will be dependent on the actual location of the structure on the parcel, as well as the size and configuration (number of levels, extent of below-grade construction, etc.) of the UNIVERSITY OF COLORADO AT COLORADO SPRINGS 7

10 garage. We anticipate some deep fills (15 to 20 feet or more) may be necessary, unless the structure steps down the hillside to accommodate the existing slope of the ground surface. For planning purposes, permanent cut and fill slopes should be no steeper than 3:1 (horizontal to vertical). Our office should be contacted to review the site grading plans once they are prepared. Prior to grading fill placement, surficial stockpiles of construction debris, organic materials, and vegetation should be stripped away from the ground surface and removed from the site. Organic topsoil can be stockpiled for later use in landscaped areas. Existing fill encountered on the site should be excavated to expose the underlying natural soils. We anticipate a thick layer of existing fill may be present along the eastern edge of the site, adjacent to Stanton Road. Existing fill materials should be observed by our representative to determine if the soils are suitable for incorporation into the planned site grading. All remnants of the concrete structures and backfill materials associated with the existing detention basins located in the northwest corner of the property, that impact the location of the planned garage should be removed from the site before grading of the property can begin. All organics and soft soils should be removed from the bottom of the basins to expose firm, natural soils, prior to fill placement. Our experience suggests a subsurface drain system should be constructed in the bottom of the existing detention basins, prior to placement of grading fill materials. The drain will provide an exit point for surficial runoff that penetrates into the backfill soils and that may otherwise pond in the bottom of the basins. For planning purposes, we anticipate the drain will consist of washed concrete aggregate wrapped in a non-woven, geotextile fabric. The location of the drain can be established once a grading plan has been developed and the position of the parking garage has been established. Fill materials within the garage footprint should consist of the on-site sands and sandstone. Sandstone placed as grading fill should be mechanically broken down into particles of less than 2 inches in diameter. Expansive claystone bedrock should be placed as fill outside of the planned building footprint as much as possible or be removed from the site. The granular grading fill should be moisture conditioned to within UNIVERSITY OF COLORADO AT COLORADO SPRINGS 8

11 2 percent of optimum moisture content and compacted in thin lifts to at least 95 percent of maximum modified Proctor dry density (ASTM D 1557). Sandy clays and claystone placed as fill should be moisture conditioned to between 1 and 4 percent above optimum moisture content and compacted to at least 95 percent of maximum standard Proctor dry density (ASTM D 698). The placement and compaction of the grading fill should be observed and tested by a representative of our office during construction. Where the existing ground surface exists at a slope ratio of 5:1 (horizontal to vertical) or steeper, benches should be cut into the hillside, prior to the placement of fill. The benches should be at least 10 feet in width or one and a half times the width of the compaction equipment, whichever is greater. The vertical distance between benches should not exceed 5 feet. Our borings suggest the on-site soils and bedrock can be excavated using conventional, heavy-duty equipment. The grading fill and natural soils will likely cave into unsupported, near-vertical utility trench excavations. Based on the Occupational Safety and Health Administration (OSHA) criteria governing excavations, the grading fills and natural soils will probably classify as Type C soils. The bedrock will probably classify as Type B soil. Temporary excavations in Type B and Type C materials require a maximum slope inclination of 1:1 and 1.5:1 (horizontal to vertical), respectively, unless the excavation is shored or braced. Should groundwater seepage occur, flatter slopes may be necessary. The contractor s competent person should evaluate the soils at the time of excavation and determine appropriate safety measures. We recommend clayey utility trench backfill be placed in thin, loose lifts, moisture conditioned to within 2 percent of optimum moisture content, and compacted to at least 95 percent of maximum standard Proctor dry density (ASTM D 698). Granular trench backfill should be moisture conditioned to within 2 percent of optimum moisture content and compacted in thin lifts to at least 95 percent of maximum modified Proctor dry density (ASTM D 1557). Personnel from our firm should periodically observe utility trench backfill placement and test the density of the backfill materials during construction. UNIVERSITY OF COLORADO AT COLORADO SPRINGS 9

12 CONSTRUCTION CONSIDERATIONS Our preliminary opinions regarding foundations, slabs-on-grade, below-grade construction, and pavements are presented below for the anticipated construction. Once plans for the parking garage become more defined, our office should be contacted to provide specific design criteria and construction recommendations. Foundations Based on our understanding of the planned construction and data from our exploratory borings, subsurface conditions beneath the proposed parking garage could possibly consist of potentially widely varying thicknesses of grading fill, natural sand and clay soils, and claystone and sandstone bedrock. To reduce the risk of excessive total and differential movements of potentially heavily-loaded foundation walls, we recommend the garage be planned considering a drilled pier foundation bottomed in the underlying bedrock. For planning purposes, we anticipate a maximum allowable end pressure of 25,000 to 35,000 psf and an allowable skin friction of 2,500 to 3,500 psf for the portion of pier in comparatively unweathered bedrock will be appropriate for preliminary pier sizing. We anticipate a minimum deadload pressure of 10,000 to 15,000 psf will be appropriate for initial design. The presence of potentially caving sands at the site may require the use of temporary casing to install some of the drilled piers. Our office should provide site-specific foundation recommendations and design criteria for the planned structure after site grading plans have been prepared and the building location and lowest floor elevation have been established. Slabs-on-Grade We expect the lowest level of the parking garage will include a concrete slab-ongrade. We judge the risk of poor slab performance will likely be low where new, sandy to clayey, moisture conditioned and densely compacted grading fill, natural sand, and/or sandstone are present at or near slab elevations. Should claystone bedrock be encountered at or near the slab elevation, subexcavation of the claystone and replacement with moisture conditioned granular fill will likely be an appropriate method to mitigate the effects of the expansive material. The risks associated with poor slab-on- UNIVERSITY OF COLORADO AT COLORADO SPRINGS 10

13 grade performance cannot be evaluated fully until the plans become better defined and floor slab elevations are established. Below-Grade Construction We anticipate portions of the proposed parking garage will be constructed below exterior grades. The foundation walls will be subjected to lateral earth loads that are dependent on the height of the wall, soil type, and backfill configuration. For backfill materials that consist of the on-site, silty to clayey sands and walls that are not free to rotate, such as foundation walls, we recommend the walls be designed to resist at-rest earth pressures. We recommend design for the at-rest earth pressure condition using an equivalent fluid density of at least 60 pcf. Claystone should not be used as wall backfill. For planning purposes, foundation drain installation should be anticipated around all habitable, below-grade construction within the project site, with the possible exception of non-habitable areas that can be constructed as water-tight structures, such as elevator pits. Pavements Pavement subgrade soils across the site will likely consist of new, sandy to clayey grading fills and natural, silty to clayey sands and sandy to very sandy clay. We anticipate the grading fills and natural sands will generally provide good subgrade support characteristics for pavement systems. The natural clay will provide comparatively poor pavement support qualities. Where granular subgrade soils are encountered, pavement thicknesses for full-depth asphalt concrete sections for access driveways in the range of 4 to 6 inches are likely. Pavement thicknesses for full-depth asphalt concrete sections in areas where clay is the predominant subgrade material will likely be on the order of 1 to 2 inches thicker. The concrete pavement anticipated in the lowest level of the parking garage is expected to be on the order of 5 to 6 inches thick. When possible during grading, sands should be placed in the upper 2 feet of the subgrade in pavement areas to reduce the required section thickness. Final pavement section recommendations can be provided once site development and grading plans are prepared. UNIVERSITY OF COLORADO AT COLORADO SPRINGS 11

14 CONCRETE Concrete in contact with soils can be subject to sulfate attack. We measured the soluble sulfate concentration in one sample from this site at less than 0.1 percent. Sulfate concentrations less than 0.1 percent indicate Class 0 exposure to sulfate attack for concrete in contact with the subsoils, according to ACI 201.2R-01, as published in the 2008 American Concrete Institute (ACI) Manual of Concrete Practice. For this level of sulfate concentration, the ACI indicates Type I/II cement can be used for concrete in contact with the subsoils. In our experience, superficial damage may occur to the exposed surfaces of highly permeable concrete, even though sulfate levels are relatively low. To control this risk and to resist freeze-thaw deterioration, the water-to-cementitious material ratio should not exceed 0.50 for concrete in contact with soils that are likely to stay moist due to surface drainage or high water tables. Concrete subjected to freezethaw cycles should be air entrained. SURFACE DRAINAGE The performance of this project will be influenced by surface drainage. When developing an overall drainage plan, consideration should be given to drainage around the proposed structure and away from paved areas. Drainage should be planned such that surface runoff is directed away from foundations and is not allowed to pond adjacent to the parking garage or over pavements. We recommend slopes of at least 6 inches in the first 10 feet for the area surrounding the structure, where possible. Roof downspouts and other water collection systems should discharge well beyond the limits of all backfill around the structure. Proper control of surface runoff is also important to prevent the erosion of surface soils. Sheet flow should not be directed over unprotected slopes. Water should not be allowed to pond at the crest of slopes. Permanent slopes should be seeded or mulched to reduce erosion. Special attention should be paid to compact soils behind the curb and gutter sections adjacent to streets and in utility trenches. CONSTRUCTION OBSERVATIONS We recommend that CTL Thompson, Inc. provide observation and testing services during construction to allow us the opportunity to verify whether soil conditions UNIVERSITY OF COLORADO AT COLORADO SPRINGS 12

15 are consistent with those found during our investigation. If others perform these observations, they must accept responsibility to judge whether the recommendations in this report remain appropriate. GEOTECHNICAL RISK The concept of risk is an important aspect with any geotechnical evaluation primarily because the methods used to develop geotechnical recommendations do not comprise an exact science. We never have complete knowledge of subsurface conditions. Our analysis must be tempered with engineering judgment and experience. Therefore, the recommendations presented in any geotechnical evaluation should not be considered risk-free. Our preliminary recommendations represent our judgment of those measures that are necessary to increase the chances that the structure will perform satisfactorily. It is critical that all recommendations in this report are followed during design and construction. LIMITATIONS Plans for the proposed building were in the preliminary conceptual phase at the time of this report. The recommendations presented should be considered to be preliminary. Once the plans become better defined, our firm should be contacted to formulate geotechnical design criteria and construction recommendations. Our borings were located to obtain a reasonably accurate indication of subsurface foundation conditions. The borings are representative of conditions encountered at the exact boring location only. Variations in subsurface conditions not indicated by the borings are possible. We recommend a representative of our office observe the completed foundation excavation. Representatives of our firm should be present during construction to perform construction observation and materials testing services. We believe this investigation was conducted with that level of skill and care normally used by geotechnical engineers practicing in this area at this time. No warranty, express or implied, is made. If we can be of further service in discussing the contents of UNIVERSITY OF COLORADO AT COLORADO SPRINGS 13

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19 APPENDIX A SWELL CONSOLIDATION TEST RESULTS TABLE A-1 SUMMARY OF LABORATORY TESTING UNIVERSITY OF COLORADO AT COLORADO SPRINGS

20 7 6 5 EXPANSION UNDER CONSTANT PRESSURE DUE TO WETTING COMPRESSION % EXPANSION APPLIED PRESSURE - KSF CLAYSTONE, SANDY DRY UNIT WEIGHT= 112 PCF TH-2 AT 24 FEET MOISTURE CONTENT= 18.7 % UNIVERSITY OF COLORADO AT COLORADO SPRINGS S:\CS \CS \115\2. REPORTS\CS _SWELL.XLS Swell Consolidation Test Results FIG. A-1

21 3 2 EXPANSION UNDER CONSTANT PRESSURE DUE TO WETTING 1 COMPRESSION % EXPANSION APPLIED PRESSURE - KSF CLAYSTONE, WEATHERED DRY UNIT WEIGHT= 101 PCF TH-3 AT 14 FEET MOISTURE CONTENT= 24.4 % 3 2 EXPANSION UNDER CONSTANT PRESSURE DUE TO WETTING 1 COMPRESSION % EXPANSION APPLIED PRESSURE - KSF CLAYSTONE, VERY SANDY DRY UNIT WEIGHT= 112 PCF TH-3 AT 24 FEET MOISTURE CONTENT= 16.3 % UNIVERSITY OF COLORADO AT COLORADO SPRINGS S:\CS \CS \115\2. REPORTS\CS _SWELL.XLS Swell Consolidation Test Results FIG. A-2

22 3 2 EXPANSION UNDER CONSTANT PRESSURE DUE TO WETTING 1 COMPRESSION % EXPANSION APPLIED PRESSURE - KSF SAND, VERY CLAYEY (SC) DRY UNIT WEIGHT= 98 PCF TH-4 AT 4 FEET MOISTURE CONTENT= 9.2 % 3 2 EXPANSION UNDER CONSTANT PRESSURE DUE TO WETTING 1 COMPRESSION % EXPANSION APPLIED PRESSURE - KSF SANDSTONE, CLAYEY DRY UNIT WEIGHT= 110 PCF TH-4 AT 19 FEET MOISTURE CONTENT= 18.1 % UNIVERSITY OF COLORADO AT COLORADO SPRINGS S:\CS \CS \115\2. REPORTS\CS _SWELL.XLS Swell Consolidation Test Results FIG. A-3

23 TABLE A-1 SUMMARY OF LABORATORY TESTING ATTERBERG LIMITS SWELL TEST RESULTS* PASSING WATER MOISTURE DRY LIQUID PLASTICITY APPLIED SWELL NO. 200 SOLUBLE DEPTH CONTENT DENSITY LIMIT INDEX SWELL PRESSURE PRESSURE SIEVE SULFATES BORING (FEET) (%) (PCF) (%) (%) (%) (PSF) (PSF) (%) (%) DESCRIPTION TH SAND, SILTY (SM) TH SAND, SILTY (SM) TH SAND, SILTY (SM) TH SAND, VERY CLAYEY (SC) TH SAND, CLAYEY (SC) TH SAND, SILTY (SM) TH CLAYSTONE, SANDY TH FILL, SAND, CLAYEY TH <0.1 SAND, SILTY (SM) TH CLAYSTONE, WEATHERED TH CLAYSTONE, VERY SANDY TH SAND, VERY CLAYEY (SC) TH CLAY, VERY SANDY (CL) TH SANDSTONE, CLAYEY TH SAND, SILTY (SM) TH SAND, CLAYEY (SC) TH CLAYSTONE, SANDY TH CLAYSTONE, VERY SANDY * SWELL MEASURED WITH ESTIMATED IN-SITU OVERBURDEN PRESSURE. NEGATIVE VALUE INDICATES COMPRESSION. Page 1 of 1