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HomeMy WebLinkAboutPVH MEDICAL OFFICE BUILDING & PARKING STRUCTURE - PDP - 14-07 - SUBMITTAL DOCUMENTS - ROUND 1 - GEOTECHNICAL (SOILS) REPORT (3)Geotechnical Engineering Report Poudre Valley Hospital — Parking Garage N/W/C of Lemay Avenue and Garfield Street Fort Collins, Colorado Project No. 20065163 1rerraroo that protective slopes be provided with a minimum grade of approximately 5 percent for at least 10 feet from perimeter walls. Backfill against footings,,extedor walls, and in utility and sprinkler line trenches should be well compacted and free of all construction debris to reduce the possibility of moisture infiltration. Downspouts, roof drains or scuppers should discharge into splash blocks or extensions when the ground surface beneath such features is not protected by exterior slabs or paving. Sprinkler systems should not be installed within 10-feet of foundation walls. Landscaped irrigation adjacent to the foundation system should be minimized or eliminated. GENERAL COMMENTS Terracon should be retained to review the final design plans and specifications so comments can be made regarding interpretation and implementation of our geotechnical recommendations in the design and specifications. Terracon also should be retained to provide testing and observation during excavation, grading, foundation and construction phases of the project. The analysis and recommendations presented in this report are based upon the data obtained from the borings performed at the indicated locations and from other information discussed in this report. This report does not reflect variations that may occur between borings, across the site, or due to the modifying effects of weather. The nature and extent of such variations may not become evident until during or after construction. If variations appear, we should be immediately notified so that further evaluation and supplemental recommendations can be provided. The scope of services for this project does not include either specifically or by implication any environmental or biological (e.g., mold, fungi, bacteria) assessment of the site or identification or prevention of pollutants, hazardous materials or conditions. If the owner is concerned about the potential for such contamination or pollution, other studies should be undertaken. This report has been prepared for the exclusive use of our client for specific application to the project discussed and has been prepared in accordance with generally accepted geotechnical engineering practices. No warranties, either express or implied, are intended or made. Site safety, excavation support, and dewatering requirements are the responsibility of others. In the event that changes in the nature, design, or location of the project as outlined in this report are - planned, the conclusions and recommendations contained in this report shall not be considered valid unless Terracon reviews the changes and either verifies or modifies the conclusions of this report in writing. I7 16 Geotechnical Engineering Report lrerraton Poudre Valley Hospital — Parking Garage J NM/C of Lemay Avenue and Garfield Street Fort Collins, Colorado Project No. 20065163 Corrosion Protection 7 Results of soluble sulfate testing indicate that ASTM Type I Portland cement is suitable for all concrete on and below grade. However, if there is no, or minimal cost differential, use of ASTM Type II Portland cement is recommended for additional sulfate resistance of construction concrete. Foundation concrete should be designed in accordance with the provisions of the ACI Design Manual, Section 318, Chapter 4. Laboratory test results indicate that on -site soils have resistivities ranging from approximately 2,270 to 2,940 ohm -centimeters, pH values ranging from 7.1 to 7.3, oxidation-reduction (Redox) potential ranging from 96 to 140 milli -volts, (mV), along with trace amounts of sulfide 1 contents, or below the laboratory detection limits of 0.1 mg/kg. These values should be used J to determine potential corrosive characteristics of the on -site soils with respect to contact with the various underground materials, which will be used during the projects construction phases. Underground Utility Systems All piping should be adequately bedded for proper load distribution. It is suggested that clean, graded gravel compacted to 75 percent of Relative Density ASTM D4253 be used as bedding. Utility trenches should be excavated on safe and stable slopes in accordance Jwith OSHA regulations as discussed above. Backfill should consist of the on -site soils or imported material approved by the geotechnical engineer. The pipe backfill should be compacted to a minimum of 95 percent of Standard Proctor Density ASTM D698. Temporary dewatering measures may be required if utility excavations are required to be extended to or near existing groundwater levels. 1 Surface Drainage All grades must provide effective drainage away from thebuilding during and after _I construction. Water permitted to pond next to the building can result in greater soil movements than those discussed in this report. These greater movements can result in unacceptable differential floor slab movements, cracked slabs and walls, and roof leaks. Estimated movements described in this report are based on effective drainage for the life of the structure and cannot be relied upon if effective drainage is not maintained. Positive drainage should be provided during construction and maintained throughout the life of the proposed project. Infiltration of water into utility or foundation excavations must be prevented during construction. Planters and other surface features, which could retain water in areas adjacent to the building or pavements, should be sealed or eliminated. In areas where sidewalks or paving do not immediately adjoin the structure, we recommend 1 15 _ 1 Geotechnical Engineering Report lrerracan Poudre Valley Hospital — Parking Garage NNW/C of Lemay Avenue and Garfield Street Fort Collins, Colorado Project No. 20065163 The soils to be penetrated by the proposed excavations may vary significantly across the site. The preliminary soil classifications are based solely on the materials encountered in widely spaced exploratory test borings. The contractor should verify that similar conditions exist throughout the proposed area of excavation. If different subsurface conditions are encountered at the time of construction, the actual conditions should be evaluated to determine any excavation modifications necessary to maintain safe conditions. J As a safety measure, it is recommended that all vehicles and soil piles be kept to a minimum lateral distance from the crest of the slope equal to no less than the slope height. J The exposed slope face should be protected against the elements. Additional Design and Construction Considerations Exterior Slab Design and Construction Compacted subgrade or existing clay soils will expand with increasing moisture content; therefore, exterior concrete grade slabs may heave, resulting in cracking or vertical offsets. The potential for damage would be greatest where exterior slabs are constructed adjacent to the building or other structural elements. To reduce the potential for damage, we recommend: • exterior slabs be supported on fill with no, or very low expansion potential • strict moisture -density control during placement of subgrade fills • placement of effective control joints on relatively close centers and isolation joints between slabs and other structural elements • provision for adequate drainage in areas adjoining the slabs • use of designs which allow vertical movement between the exterior slabs and adjoining structural elements In those locations where movement of exterior slabs cannot be tolerated or must be reduced, consideration should be given to: Constructing slabs with a stem or key -edge, a minimum of 6 inches in width and at least 12 inches below grade; • supporting keys or stems on drilled piers or screw piles; or • providing structural exterior slabs supported on foundations similar to the building. 14 Geotechnical Engineering Report llerracon Poudre Valley Hospital — Parking Garage NMIC of Lemay Avenue and Garfield Street Fort Collins, Colorado Project No. 20065163 Fill Materials and Placement Approved imported materials may be used as fill material and are suitable for use as compacted fill beneath interior or exterior floor slabs. Imported soils (if required) should conform to the following: Gradation Percent finer by weight (ASTM C136) 3"......................................................................................................... 100 No. 4 Sieve..................................................................................... 50-100 No. 200 Sieve.............................................................................. 35 (max) • Liquid Limit.................................................................................. 30 (max) • Plasticity Index............................................................................. 15 (max) • Group Index................................................................................. 10 (max) Engineered fill should be placed and compacted in horizontal lifts, using equipment and procedures that will produce recommended moisture contents and densities throughout the lift. It is recommended all fill material to be placed on the site be compacted to at least 95 percent of Standard Proctor Density (SPD) ASTM D698. Fill material placed beneath footings, if elected to use this alternative, should be compacted to 98 percent of SPD. On -site clay soils should be compacted within a moisture content range of 2 percent below, to 2 percent above optimum. Imported granular soils should be compacted within a moisture range of 3 percent below to 3 percent above optimum unless modified by the project geotechnical engineer. Excavation and Trench Construction Excavations into the on -site soils will encounter a variety of conditions. Excavations into the clays can be expected to stand on relatively steep temporary slopes during construction. However, caving soils and groundwater may also be encountered. The individual contractor(s) should be made responsible for designing and constructing stable, temporary excavations as required to maintain stability of both the excavation sides and bottom. All excavations should be sloped or shored in the interest of safety following local and federal regulations, including current OSHA excavation and trench safety standards. 13 Geotechnical Engineering Report Poudre Valley Hospital — Parking Garage N/W/C of Lemay Avenue and Garfield Street Fort Collins, Colorado Project No. 20065163 1rerracon Demolition of any existing medical office/clinic facility planned to be- razed to accommodate the parking garage structure or any auxiliary features to accommodate the new construction, should include complete removal of all foundation systems within the proposed construction area. This should include removal of any loose backfill found adjacent to existing foundations. All materials derived from the demolition of existing structure(s) and/or pavements should be removed from the site and not be allowed for use in any on -site fills. If unexpected fills or underground facilities are encountered, such features should be removed and the excavation thoroughly cleaned prior to backfill placement and/or construction. After all existing fill is removed, exposed areas, which will receive fill, once properly cleared where necessary, should be scarified to a minimum depth of 12-inches, conditioned to near optimum moisture content, and compacted. It is anticipated that excavations for the proposed construction can be accomplished with conventional earthmoving equipment. Based upon the subsurface conditions determined from the geotechnical exploration, the majority of the underlying subgrade soils exposed during construction are anticipated to be relatively stable; however soft compressible and/or unstable areas may be encountered during construction. The stability of the subgrade may be affected by precipitation, repetitive construction traffic or other factors. If unstable conditions develop, workability may be improved by scarifying and drying. Overexcavation of wet zones and replacement with granular materials may be necessary. Use of lime, fly ash, kiln dust, cement or geotextiles could also be considered as a stabilization technique. Laboratory, evaluation is recommended to determine the effect of chemical stabilization on subgrade soils prior to construction. Lightweight excavation equipment may be required to reduce subgrade pumping. Subgrade Preparation Subgrade soils beneath interior and exterior slabs should be scarified; moisture j conditioned and compacted to a minimum depth of 12-inches below proposed controlled J fill material. The moisture content and compaction of subgrade soils should be maintained until slab or pavement construction. 12 Geotechnical Engineering Report Yerracon Poudre Valley Hospital — Parking Garage NNW/C of Lemay Avenue and Garfield Street Fort Collins, Colorado Project No. 20065163 • Positive separations and/or isolation joints should be provided between slabs and all foundations, columns or utility lines to allow independent movement. • Control joints should be provided in slabs to control the location and extent of cracking. • Interior trench backfill placed beneath slabs should be compacted in accordance with recommended specifications outlined below. • A minimum 6-inch layer of clean -graded gravel or aggregate base course should be placed beneath slabs on grade. • Floor slabs should not be constructed on frozen subgrade. • Other design and construction considerations, as outlined in the ACI Design Manual, Section 302.1 R are recommended. Earthwork General Considerations The following presents recommendations for site preparation, excavation, subgrade preparation and placement of engineered fills on the project. All earthwork on the project should be observed and evaluated by Terracon. The evaluation of earthwork should include observation and testing of engineered fill, subgrade preparation, foundation bearing soils, and other geotechnical conditions exposed during the construction of the project. Site Preparation Strip and remove any existing debris, fill material and/or other deleterious materials from 1 proposed building areas. All exposed surfaces should be free of mounds and depressions J that could prevent uniform compaction. The site should be initially graded to create a relatively level surface to receive fill, and .to provide for a relatively uniform thickness of fill beneath proposed building addition. 11 Geotechnical Engineering Report lrerracon Poudre Valley Hospital — Parking Garage NNW/C of Lemay Avenue and Garfield Street Fort Collins, Colorado Project No. 20065163 Fill against grade beams and retaining walls should be compacted to densities specified in Earthwork. Medium to high plasticity clay soils or claystone bedrock should not be used as - - backfill against retaining walls. Compaction of each lift adjacent to walls should be accomplished with hand -operated tampers or other lightweight compactors. Overcompaction may cause excessive lateral earth pressures, which could result in wall movement. Seismic Considerations The project site is located in Seismic Risk Zone I of the Seismic Zone Map of the United States as indicated by the 1997 Uniform Building Code. Based upon the nature of the subsurface materials, Soil Profile Type "Sc" should be used for the design of structures for the proposed project (1997 Uniform Building Code, Table No. 16-J). A site classification "C" should be used for the design of structures for the proposed project (2003 International Building Code, Table No. 1615.1.1). Floor Slab Design and Construction Some differential movement of a slab -on -grade floor system is possible should the subgrade soils become elevated in moisture content. To reduce potential slab movements, the subgrade soils should be prepared as outlined in the earthwork section of this report. For structural design of concrete slabs -on -grade, a modulus of subgrade reaction of 100 pounds per cubic inch (pci) may be used for floors supported on existing soils. A modulus of 200 pci may be used for floors supported on non -expansive imported structural fill material approved by the geotechnical engineer. This report provides recommendations to help mitigate the effects of soil shrinkage and expansion. However, even if these procedures are followed, some movement and at least minor cracking in the structure's foundation system and floor slab should be anticipated. The severity of cracking and other cosmetic damage such as uneven floor slabs will probably increase if any modification of the site results in excessive wetting or drying of the expansive materials. Eliminating the risk of movement and cosmetic distress may not be feasible, but it may be possible to further reduce the risk of movement if significantly more expensive measures are used during construction. Some of these options, such as the use of structural floors or overexcavating and replacing expansive materials are discussed in this report. We would be pleased to discuss other construction alternatives with you upon request. Additional floor slab design and construction recommendations for floor slabs are as follow: • Remove all existing fill material where encountered, from below proposed slabs and replaced with approved engineered fill material. 10 Geotechnical Engineering Report Terracon Poudre Valley Hospital — Parking Garage N/W/C of Lemay Avenue and Garfield Street Fort Collins, Colorado Project No. 20065163 Screw piles should be considered to work in group action if the horizontal spacing is less than 3 pile diameters. A minimum practical horizontal spacing between piles of at least 3 diameters should be maintained, and adjacent piles should bear at the same elevation. The capacity of individual piles must be reduced when considering the effects of group action. Capacity reduction is a function of pile spacing and the number of piles within a group. If group action analyses are necessary, capacity reduction factors can be provided for the analyses. Terracon should be consulted to review preliminary load test data, and a representative of this firm should be present to observe test and production screw pile installation to verify that proper bearing materials have been encountered during installation. Lateral Earth Pressures For soils above any free water surface, recommended equivalent fluid pressures for unrestrained foundation elements are: • Active: Cohesive soil backfill (on -site clay soils).................................45 psf/ft Cohesionless soil backfill (imported granular soils).................35 psf/ft On -site bedrock materials ........................... not recommended for use • Passive: Cohesive soil backfill (on -site clay soils)...............................250 psf/ft Cohesionless soil backfill (imported granular soils)...............350 psf/ft Drilled Piers..........................................................................500 psf/ft Where the design includes restrained elements, the following equivalent fluid pressures are recommended: • At rest: Cohesive soil backfill (on -site clay soils).................................60 psf/ft Cohesionless soil backfill (granular imported soils).................50 psf/ft On -site bedrock materials ........................... not recommended for use The lateral earth pressures herein do not include any factor of safety and are not applicable for submerged soils/hydrostatic loading. Additional recommendations may be necessary if submerged conditions are to be included in the design. 9 Geotechnical Engineering Report Poudre Valley Hospital — Parking Garage NMIC of Lemay Avenue and Garfield Street Fort Collins, Colorado Project No. 20065163 lrerracon be installed in less time than a drilled pier and there is no need for concrete or additional reinforcement. Casing is not necessary and the screw pile(s) can also be loaded up to approximately 500 kips per location, or a series of screw piles can be installed to achieve a greater concentrated loading arrangement as well as to resist laterally loaded conditions. As part of the design phase and the determination of loading parameters, the installer can conduct an installation demonstration to the design team as they become more familiar with the expected subsurface conditions, (i.e. the depth to bedrock, drilled pier design parameters and groundwater conditions). The installer can also provide a site -specific load test to determine the achievable torque necessary to support the anticipated maximum wall and column loads for the Poudre Valley Hospital Parking Garage Structure project. Terracon's design parameters for the use of drilled piers, which includes end bearing and skin friction characteristics as well as depth to bedrock, are presented in this geotechnical engineering report. The screw pile designer can design a screw pile foundation system to accommodate the maximum wall and column loads for the project based on the structural engineer's load design calculations as well as a pile cap/foundation wall system. The screw piles will vary with depth from north to south and generally follow the bedrock contours. The screw piles should extend into the underlying bedrock formation sufficiently to achieve the design torque to support the anticipated loading parameters. A screw pile is installed to a design torque and not necessarily a required depth of penetration into the bedrock. As long as the required torque is achieved the screw install is then terminated. Typically, depending upon the design loads as well as the design torque, a screw pile may only extend into the bedrock a few feet. The screw pile designer can design the screw pile system with the necessary pipe diameter, wall thickness, and helix flight configuration to accommodate the project. An experienced screw pile contractor should be consulted to review the Logs of Borings provided y herein. Groundwater and variable depth to medium hard to very hard claystone bedrock with Jintermittent sandstone lenses encountered at the site could result in pile installation difficulties. At a minimum, we recommend that test piles/load test procedures be conducted to determine the appropriate design parameters for the site, (i.e. tested for axial and lateral capacity prior to installing production piles). If lateral load testing cannot be performed, a sufficient number of battered piles should be installed to resist all lateral loading imposed. The actual design of the piles including the pile capacity, spacing, helix diameter(s), shaft length, bracket attachment and configuration, and shaft diameter should be performed by an experienced screw pile contractor and designed by a licensed structural engineer. As previously outlined, due to the relatively shallow depth to bedrock, an experienced screw pile contractor should review the data to assess whether heavy-duty equipment or pre -drilling will be required to achieve the minimum length and capacity. 8 Geotechnical Engineering Report Poudre Valley Hospital — Parking Garage NIW/C of Lemay Avenue and Garfield Street Fort Collins, Colorado Project No. 20065163 lrerraon Drilling caissons should be possible with conventional single flight power augers within the weathered portions of the underlying bedrock formation. Areas of well -cemented sandstone bedrock will be encountered at increased depths where specialized drilling equipment and/or rock augers will be required. Consideration should be given to obtaining a unit price for difficult caisson excavation in the contract documents for the project. Shafts will probably remain open without stabilizing measures. However, pier concrete should be placed soon after completion of drilling and cleaning. Groundwater was measured in each of the nine (9) test borings at approximate depths of 19 to 26-feet below site grades during initial drilling operations. Therefore temporary casing will be required. The use of a tremie may be needed to adequately/properly drill and clean piers prior to concrete placement. If encountered during caisson drilling operations, the groundwater should be removed from each pier hole prior to concrete placement. Pier concrete should be placed immediately after completion of drilling and cleaning. A maximum 3-inch depth of groundwater is acceptable in each pier prior to concrete placement. If pier concrete cannot be placed in dry conditions, a tremie should be used for concrete placement. Due to potential sloughing and raveling, foundation concrete quantities may exceed calculated geometric volumes. Pier concrete with slump in the range of 6 to 8 inches is recommended. If casing is used for pier construction, it should be withdrawn in a slow continuous manner maintaining a sufficient head of concrete to prevent infiltration of water or the creation of voids in pier concrete. Foundation excavations should be observed by the geotechnical engineer. A representative of the geotechnical engineer should inspect the bearing surface and pier configuration. If the soil conditions encountered differ significantly from those presented in this report, supplemental recommendations will be required. Alternative Foundation System — Steel Screw Piles An alternative foundation system to consider for this project, due to the depth to the underlying 1 bedrock formation as well as the presence of groundwater, would be the use of steel screw piles. Due to the depth to groundwater as well as the necessity to case each drilled pier/caisson and also depending upon the time of year for construction, it is Terracon's opinion that the use of screw piles 1 are a viable alternative for this site. 1 There are several benefits for using a screw pile design concept versus a drilled pier in certain 1 situations, especially in cases where the bedrock is encountered at depths greater than 20-feet below site grades and when groundwater is present. Depending on the contractor, a screw pile can 7 I Geotechnical Engineering Report Poudre Valley Hospital — Parking Garage NNW/C of Lemay Avenue and Garfield Street Fort Collins, Colorado Project No. 20065163 lrerracon All piers should be reinforced full depth for the applied axial, lateral and uplift stresses imposed. The tensile force created by the uplift force on each pier, with allowance for dead load, should determine the amount of reinforcing steel for expansion. To satisfy forces in the horizontal direction, piers may be designed for lateral loads using a modulus of 75 tons per square foot for the portion of the pier in clays and/or engineered fill, and 400 tsf in bedrock for a pier diameter of 12 inches. The coefficient of subgrade reaction for varying pier diameters is as follows: When the lateral capacity of drilled piers is evaluated by the L-Pile (COM 624) computer program, we recommend that internally generated load -deformation (P-Y) curves be used. The following parameters may be used for the design of laterally loaded piers, using the L-Pile (COM 624) computer program: Unit Weight of Soil (pcf) 130 115(') 125(') Cohesion (psf) 0 1500 5000 Angle of Internal Friction 0 35 25 20 (degrees) Strain Corresponding to % Max. I I 0.02 I 0.015 Principal Stress Difference c50 "Notes: 1) Use of 65 PCF below the water table To reduce potential uplift forces on piers, use of long grade beam spans to increase individual pier loading, and small diameter piers are recommended. For this project, use of a minimum pier diameter of 18-inches is recommended. 11 6 Geotechnical Engineering Report lferracon Poudre Valley Hospital — Parking Garage NIW/C of Lemay Avenue and Garfield Street Fort Collins, Colorado Project No. 20065163 Zones of perched and/or trapped groundwater may occur at times in the subsurface soils overlying bedrock, on top of the bedrock surface or within permeable fractures in the bedrock materials. The location and amount of perched water is dependent upon several factors, including hydrologic conditions, type of site development, irrigation demands on or adjacent to the site, fluctuations in water features, seasonal and weather conditions. Based upon review of U.S. Geological Survey maps ('Hillier, et al, 1983), regional groundwater is expected to be encountered in unconsolidated alluvial deposits on the site, at depths ranging from 10 to 20 feet below the existing ground surface at the project site. ENGINEERING ANALYSES AND RECOMMENDATIONS Geotechnical Considerations The site appears suitable for the proposed construction from a geotechnical engineering point of view. Due to on -site subsurface conditions, complexity of the project, foundation bearing levels, and structural loads, the following foundation system was evaluated for use on the site: • Grade beams and straight shaft drilled piers/caissons extending into the underlying bedrock formation; and • Steel Screw Piles installed into the underlying bedrock formation to design torque values established during a "pre -design" load -test demonstration. Foundation Systems — Drilled Piers/Caissons Due to the anticipated loading conditions for the proposed Poudre Valley Hospital 4-story parking garage structure and associated stair tower, it is recommended that either a grade beam and drilled pier/caisson foundation system or a screw pile foundation system be used to support the proposed structure. Straight shaft piers, drilled a minimum of 10-feet into competent or harder bedrock, with minimum shaft lengths of 25-feet are recommended and should be designed using a maximum end bearing of 45,000 psf, along with a skin friction of 4,500 psf. The drilled piers should also be designed to maintain a minimum dead load of 5,000 psf. ' Hillier, Donald E.; Schneider, Paul A., Jr.; and Hutchinson, E. Carter, 1983, Depth to Water Table (1979) in the Boulder - Fort Collins -Greeley Area, Front Range Urban Corridor, Colorado, United States Geological Survey, Map 1-855-I. P Geotechnical Engineering Report Poudre Valley Hospital — Parking Garage N/W/C of Lemay Avenue and Garfield Street Fort Collins, Colorado Project No. 20065163 lferramn stratum was encountered at approximate depths of 2 to 6-feet below site grades and extended to the fine to coarse granular strata below. Silty sand and silty sand with gravel was encountered in each boring at approximate depths of 20 to 27-feet below site grades and extended to the bedrock below. Sandstone/siltstone bedrock with intermittent cemented sandstone lenses was encountered in each of the test borings at approximate depths of 31 to 33-feet below site grades and extended to the depths explored, approximately 44-1/2-feet below site grades. Field and Laboratory Test Results Field and laboratory test results indicate the native cohesive clay at shallow depths are very soft to stiff in consistency, exhibit low swell potential and low to moderate bearing characteristics. The fine to course granular strata is medium dense to dense in relative density and exhibits non - expansion potential and moderate bearing characteristics. The bedrock stratum varies from moderately hard to very with increasing depths and generally exhibits a low to moderate swell potential and moderate to high bearing characteristics. The existing on -site fill material is not suitable for support of footings or floor slabs without over excavating, moisture conditioning and recompacting to the specifications contained in the "Earthwork" section of this report. The competent siltstone bedrock with interbedded sandstone lenses revealed Standard Penetration Test (SPT — N Blows/foot) results with increased depths within the cemented lenses of approximately 50 blows with a 140-pound hammer falling 30-inches, penetrating 1 to 7-inches. The hard, well cemented sandstone lenses at increased depths throughout the site may require the use of specialized heavy-duty equipment to achieve designed elevations. Excavations penetrating the well -cemented bedrock may require the use of a rock hammer or core barrel to achieve final design elevations. Consideration should be given to obtaining a unit price for difficult excavation in the contract documents for the project. Groundwater Conditions Groundwater was measured in each of the test borings at approximate depths of 19 to 26-feet below site grades during the initial field exploration activities. Upon completion of the drilling operations the test borings were backfilled with auger cuttings for safety purposes; therefore, stabilized groundwater measurements were not obtained. These observations represent groundwater conditions at the time of the field exploration, and may not be indicative of other times, or at other locations. Groundwater levels can be expected to fluctuate with varying seasonal and weather conditions. 4 Geotechnical Engineering Report lrerracon Poudre Valley Hospital — Parking Garage I NM/C of Lemay Avenue and Garfield Street Fort Collins, Colorado Project No. 20065163 Classification System described in Appendix C. Samples of bedrock were classified in -I accordance with the general notes. for Bedrock Classification. At that time, the field descriptions were confirmed or modified as necessary and an applicable laboratory testing program was formulated to determine engineering properties of the subsurface materials. Boring logs were prepared and are presented in Appendix A. Laboratory tests were conducted on selected soil samples and are presented in Appendix B. The test results were used for the geotechnical engineering analyses, and the development of foundation and earthwork recommendations. All laboratory tests were performed in general accordance with the applicable local or other accepted standards. Selected soil and bedrock samples were tested for the following engineering properties: • Water Content • Dry Density • Swell -Consolidation • Grain -Size Distribution SITE CONDITIONS • Plasticity Index • Water Soluble Sulfates • Resistivity, pH, Sulfide • Oxidation Reduction The site for the proposed 4-story parking garage structure is situated north of Garfield Street and west of Lemay Avenue. The majority of the site is currently occupied by an existing asphalt paved parking area with a medical clinic office building situated near the southwest portion of the site. We understand this building is to be razed to accommodate the new parking structure. Robertson Street borders the site to the west with the Lemay Medical Park located beyond and existing business establishments located to the north. The existing Lemay Avenue PVH building is located on the east side of Lemay Avenue directly across from the proposed parking structure. SUBSURFACE CONDITIONS Soil and Bedrock Conditions The subsurface conditions encountered within eight (8) of the nine (9) test borings generally consisted of an approximate 2 to 5-inch layer of existing asphalt pavement underlain by approximately 2 to 6-inches of aggregate base course. Test Boring No. 2 was drilled within an existing landscape island and an approximate 6-inch of vegetation was encountered at the surface. Underlying the surface layers at each boring was sandy lean clay with trace amounts of gravel fill material, which extended to the native subsoils below. The native sandy lean clay 9 Geotechnical Engineering Report Poudre Valley Hospital — Parking Garage 1 NNV/C of Lemay Avenue and Garfield Street Fort Collins, Colorado Project No. 20065163 lrenzon respectively. Based on our experience with similar type projects as well as our knowledge of the site, we anticipate the use of a drilled pier/caisson foundation system to be utilized for supporting the proposed structure. Although final site grading plans were not available at the time of the J preparation of this report, it is assumed first floor level will be at or slightly above existing site grade elevations. SITE EXPLORATION The scope of the services performed for this project included a site reconnaissance by an engineering geologist, a subsurface exploration program, laboratory testing and engineering analyses. lField Exploration J A total of nine (9) test borings were drilled on November 1, 3, 9, and 16, 2006 to approximate depths of 44-1/2-feet below existing site grades, at the locations as shown on the enclosed Test Boring Location Diagram, Figure No. 1. The borings were advanced with a truck -mounted drilling rig, utilizing 4-inch diameter solid stem and 3-1/4-inch inside diameter hollow stem augers. The borings were located in the field by using a hand held GPS unit and referenced to existing J site features. Approximate ground surface elevations were estimated at each boring location by J use of an engineer's level and referenced to a temporary benchmark (TBM), which consisted of the finish floor elevation of the existing hospital building, assuming an elevation of 4,974. The accuracy of boring locations and elevations should only be assumed to the level implied by the methods used. J Lithologic logs of each boring were recorded by the engineering geologist during the drilling operations. At selected intervals, samples of the subsurface materials were taken by means of 1 driving split -spoon and/or ring -barrel samplers. Penetration resistance measurements were obtained by driving the split -spoon or ring barrel sampler into the subsurface materials with a 140-pound hammer falling 30 inches. The penetration resistance value is a useful index in estimating the consistency, relative density or hardness of the materials encountered. Laboratory Testing All samples retrieved during the field exploration were returned to the laboratory for observation by the project geotechnical engineer and were classified in accordance with the Unified Soil N GEOTECHNICAL ENGINEERING REPORT PROPOSED POUDRE VALLEY HOSPITAL 4-STORY PARKING GARAGE 1024 LEMAY AVENUE CAMPUS NORTHWEST CORNER OF SOUTH LEMAY AVENUE AND GARFIELD STREET FORT COLLINS, COLORADO TERRACON PROJECT NO.20065163 November 30, 2006 INTRODUCTION This report contains the results of our geotechnical engineering exploration for the proposed 4- story parking garage structure to be constructed at the northwest comer of Lemay Avenue and Garfield Street for the existing Poudre Valley Hospital's Lemay Avenue Campus in Fort Collins, Colorado. The 1 site is located in the Southeast 1/4 of Section 13, Township 7 North, Range 69 West of the 6th Principal Meridian, Larimer County, Fort Collins, Colorado. The purpose of the geotechnical engineering related services is to provide information and preliminary geotechnical engineering recommendations relative to: • subsurface soil and bedrock conditions • groundwater conditions • foundation design and construction • basement construction • floor slab design and construction • earthwork • drainage The recommendations contained in this report are based upon the results of field and laboratory testing, engineering analyses, and experience with similar soil conditions, structures and our understanding of the proposed project. The recommendations presented herein generally comply with the request for proposal for geotechnical investigations prepared by the project's structural engineer, Structural Consultants, Inc., dated October 9, 2006. PROPOSED CONSTRUCTION 0 The project as we understand is to construct a 4-story, slab on grade, concrete pre -cast wall, parking garage structure west of Lemay Avenue and north of Garfield Street directly west of the existing Lemay Avenue PVH Campus. A proposed stair tower and cross -over link is also planned to connect the existing hospital and parking garage structure. We anticipate the maximum wall and column loads for the PVH parking garage structure to be on the order of 6 to 10 kips per linear foot, and 200 to 750 kips Geotechnical Engineering Report lrerracon Poudre Valley Hospital — Parking Garage NMIC of Lemay Avenue and Garfield Street Fort Collins, Colorado Project No. 20065163 APPENDIX A Figure No. 1 — Test -Boring Location Diagram Test Boring Logs — Nos. 1 through 9 APPENDIX B Laboratory Test Results APPENDIX C General Notes TABLE OF CONTENTS Page No. Letter of Transmittal..............................................................................................i INTRODUCTION..................................................................................................................1 PROPOSED CONSTRUCTION............................................................................................1 SITE EXPLORATION ....................................................... .................................................... 2 FieldExploration..........................................................................................................2 LaboratoryTesting...................................................................................................... 2 SITE CONDITIONS..............................................................................................................3 SUBSURFACE CONDITIONS..............................................................................................3 Soil and Bedrock Conditions........................................................................................3 Field and Laboratory Test Results...............................................................................4 Groundwater Conditions..............................................................................................4 ENGINEERING ANALYSES AND RECOMMENDATIONS..................................................5 Geotechnical Considerations ................... :...................................................................5 Foundation Systems — Drilled Piers/Caissons............................................................. 5 Foundation Systems — Screw Piles............................................................................. 7 Lateral Earth Pressures...............................................................................................9 Seismic Considerations.............................................................................................10 Floor Slab Design and Construction..........................................................................10 Earthwork..................................................................................................................11 General Considerations....................................................................................11 SitePreparation...............................................................................................11 Subgrade Preparation......................................................................................12 Fill Materials and Placement............................................................................13 Excavation and Trench Construction................................................................13 Additional Design and Construction Considerations..................................................14 Exterior Slab Design and Construction.............................................................14 Corrosion Protection.........................................................................................15 Underground Utility Systems............................................................................15 SurfaceDrainage.............................................................................................15 GENERALCOMMENTS.....................................................................................................16 November 30, 2006 PVHS System Development Engineering and Construction 2809 East Harmony Road — Suite 200 Fort Collins, Colorado 80528-3144 Attn: Mr. Troy Martin Re: Geotechnical Engineering Report Proposed Poudre Valley Hospital 4-Story Parking Garage 1024 South Lemay Avenue Campus Northwest Corner of Garfield Street and South Lemay Avenue Fort Collins, Colorado Terracon Project No. 20065163 Irerracon Consulting Engineers & Scientists 301 North Howes Fort Collins, Colorado 80521 Phone 970.484.0359 Fax 970.484.0454 www.terracon.com Terracon has completed a geotechnical engineering exploration for the proposed 4-story parking garage structure to be constructed at the northwest comer.of Lemay Avenue and Garfield Street for the existing Poudre Valley Hospital's Lemay Avenue Campus in Fort Collins, Colorado. This study was performed in general accordance with our Proposal No. D2006399 dated October 20, 2006. The results of our recent engineering study completed for the proposed parking garage structure including 1 the boring location diagram, test boring records, and the geotechnical recommendations needed to aid in the ! design of foundations, floor slabs, and other earth connected phases of this project are attached. We appreciate being of service to you in the geotechnical engineering phase of this project, and are prepared to assist you during the construction phases as well. If you have any questions concerning this report or any of our testing, inspection, design and consulting services, please do not hesitate to contact us. Sincerely, TERRACON _. . V* -+ i Z.C2 David A. Richer, P. ql ENG�ND g J. Job , P.E. Geotechnical Engineer/ nt Manager eotechnical Engineer/Regional Manager Copies to: Addressee (2) Structural Consultants, Inc. (2): Mr. Paul J. Hause, P.E. Stantec (2): Mr. Jim Allen -Morley, P.E. i Delivering Success for Clients and Employees Since 1965 More Than 80 Offices Nationwide i GEOTECHNICAL ENGINEERING REPORT PROPOSED POUDRE VALLEY HOSPITAL 4-STORY PARKING GARAGE 1024 LEMAY AVENUE CAMPUS NORTHWEST CORNER OF SOUTH LEMAY AVENUE AND GARFIELD STREET FORT COLLINS, COLORADO TERRACON PROJECT NO.20065163 November 30, 2006 Prepared for. PVHS System Development Engineering and Construction 2809 East Harmony Road — Suite 200 Fort Collins, Colorado 80528-3144 Attn: Mr. Troy Martin Prepared by. Terracon 301 North Howes Street Fort Collins, Colorado 80521 Irarrarnn