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HomeMy WebLinkAboutUNCOMMON (310 S. COLLEGE) - FDP - FDP150038 - SUBMITTAL DOCUMENTS - ROUND 1 - GEOTECHNICAL (SOILS) REPORTGEOTECHNICAL SUBSURFACE EXPLORATION REPORT PROPOSED MIXED USE RETAIL/STUDENT HOUSING BUILDING 310 SOUTH COLLEGE AVENUE FORT COLLINS, COLORADO EEC PROJECT NO. 1152068 Prepared for: CA Ventures 161 N Clark - Suite 4900 Chicago, Illinois 60601 Attn: Mr. Christopher Johnson (cjohnson@ca-ventures.com) VP of Planning and Entitlement | CA STUDENT LIVING Prepared by: Earth Engineering Consultants, LLC 4396 Greenfield Drive Windsor, Colorado 80550 4396 GREENFIELD DRIVE WINDSOR, COLORADO 80550 (970) 545-3908 FAX (970) 663-0282 August 11, 2015 CA Ventures 161 N Clark - Suite 4900 Chicago, Illinois 60601 Attn: Mr. Christopher Johnson (cjohnson@ca-ventures.com) VP of Planning and Entitlement | CA STUDENT LIVING Re: Geotechnical Subsurface Exploration Report Proposed Mixed Use Retail/Student Housing Building 310 South College Avenue Fort Collins, Colorado EEC Project No. 1152068 Mr. Johnson: Enclosed, herewith, are the results of the geotechnical subsurface exploration completed by Earth Engineering Consultants, LLC (EEC) for the referenced project. For this exploration, four (4) soil borings were drilled on July 1, 2015 at preselect locations within the footprint of the proposed retail/student housing building to be located at 310 South College Avenue in Fort Collins, Colorado. The borings were extended to approximate depths of 40 feet below present site grades. A prior report was completed on this site in 2005 by others; data from that prior exploration was considered in completion of this report. This study was completed in general accordance with our proposal dated June 25, 2015. In summary, the subsurface soils encountered beneath the surficial landscape/pavements, generally consisted of cohesive sandy lean clay and lean clay with sand layers, which extended to the fine to coarse granular strata below. Sand with gravel, varying fines and intermittent cobbles was encountered beneath the upper cohesive soils at depths of approximately 18 to 19½ feet below existing site grades and extended to the bedrock below. Claystone bedrock with intermittent sandstone lenses was encountered in each of the borings at depths of approximately 28 feet below existing site grades and extended to the depths explored, approximately 40 feet. Groundwater was encountered across the site during the field exploration at approximate depths of 21 to 21½ feet below existing site grades. Based on the subsurface conditions encountered in the test borings as well as the anticipated maximum loading conditions, we recommend the proposed 6 to 7-story structure be supported on a drilled pier foundation system extending into the underlying bedrock formation. We anticipate GEOTECHNICAL SUBSURFACE EXPLORATION REPORT PROPOSED MIXED USE RETAIL/STUDENT HOUSING BUILDING 310 SOUTH COLLEGE AVENUE FORT COLLINS, COLORADO EEC PROJECT NO. 1152068 August 11, 2015 INTRODUCTION The geotechnical subsurface exploration for the proposed multi-level 6 to 7-story mixed use retail/student housing building to be constructed at 310 South College Avenue in Fort Collins, Colorado, has been completed. For this exploration, four (4) soil borings extending to depths of approximately 40 feet below present site grades were drilled on July 1, 2015 at pre-selected locations within the new building footprint. Four (4) other borings were completed on the site by others in 2005; data from those borings was considered in developing the recommendations provided with this report. This exploration was completed in general accordance with our proposal dated June 25, 2015. We understand the proposed retail/student housing building will be multi-level with 6 to 7-stories above grade and possibly two levels of below grade parking. The building footprint will occupy essentially the entire site. An existing building (Perkins Restaurant) on the southern portion of the site will be demolished prior to construction of the new structure. The new building below grade parking will extend to depths on the order of 16 feet below the site surface grades. Foundation loads for the new structure are estimated to be moderate with continuous wall loads less the 6 klf and maximum column loads in the range of 450 to 750 kips. Floor loads are expected to be light. Small grade changes are expected to develop final site grades outside of the basement area. The purpose of this report is to describe the subsurface conditions encountered in the test borings, analyze and evaluate the test data and provide geotechnical recommendations concerning design and construction of foundations and support of floor slabs for the new building. EXPLORATION AND TESTING PROCEDURES The boring locations were established in the field by representatives from Earth Engineering Consultants, LLC (EEC) by pacing and estimating angles from identifiable site features. Those approximate boring locations are indicated on the attached boring location diagram. The locations of the borings should be considered accurate only to the degree implied by the methods used to make Earth Engineering Consultants, LLC EEC Project No. 1152068 August 11, 2015 Page 2 the field measurements. Photographs of the site taken at the time of drilling are included with this report. The test borings were completed using a truck mounted, CME-75 drill rig equipped with a hydraulic head employed in drilling and sampling operations. The boreholes were advanced using 4¼-inch nominal inside diameter hollow stem augers. Samples of the subsurface materials encountered were obtained using split barrel and California barrel sampling procedures in general accordance with ASTM Specifications D1586 and D3550, respectively. In the split barrel and California barrel sampling procedures, standard sampling spoons are advanced into the ground with a 140-pound hammer falling a distance of 30 inches. The number of blows required to advance the split barrel and California barrel samplers is recorded and is used to estimate the in-situ relative density of cohesionless soils and, to a lesser degree of accuracy, the consistency of cohesive soils and hardness of weathered bedrock. In the California barrel sampling procedure, relatively intact samples are obtained in removable brass liners. All samples obtained in the field were sealed and returned to our laboratory for further examination, classification, and testing. Laboratory moisture content tests were completed on each of the recovered samples. Atterberg Limits and washed sieve analysis tests were completed on selected samples to evaluate the quantity and plasticity of fines in the subgrade samples. Swell/consolidation tests were completed on selected samples to evaluate the potential for the subgrade materials to change volume with variation in moisture and load. Soluble sulfate tests were completed on selected samples to evaluate potential adverse reactions to site-cast concrete. Results of the outlined tests are indicated on the attached boring logs and summary sheets. As part of the testing program, all samples were examined in the laboratory by an engineer and classified in general accordance with the attached General Notes and the Unified Soil Classification System, based on the soil’s texture and plasticity. The estimated group symbol for the Unified Soil Classification System is indicated on the boring logs and a brief description of that classification system is included with this report. Classification of the bedrock was based on visual and tactual observation of disturbed samples and auger cuttings. Coring and/or petrographic analysis may reveal other rock types. Earth Engineering Consultants, LLC EEC Project No. 1152068 August 11, 2015 Page 3 SITE AND SUBSURFACE CONDITIONS The area for the proposed building currently includes an existing single-story building situated on the southern portion of the lot, a parking area, and small intermittent landscape areas. The site is relatively flat. Based on results of the field borings and laboratory testing, subsurface conditions can be generalized as follows. The subsurface soils encountered beneath the existing pavement section, generally consisted of cohesive sandy lean clay and lean clay with sand layers which extended to a fine to coarse granular strata below. The top 4½ feet of subgrade appeared to be previously placed fill materials. The cohesive soils were soft to firm to stiff, and exhibited low expansive characteristics with slight compressible/consolidation characteristics with increased depths. Intermittent sand and gravel lenses were encountered at increased depths within the cohesive zone. Poorly-graded sand with gravel and varying fines and intermittent cobbles was encountered beneath the upper cohesive soils at depths of approximately 18 to 19½ feet below existing site grades and extended to the bedrock below. The granular materials were dense. Siltstone/sandstone bedrock with intermittent cemented sandstone lenses was encountered in each of the borings beneath the overburden soils at depths of approximately 28 feet below existing site grades and extended to the depths explored, approximately 40 feet. The bedrock formation was weathered nearer surface; however, became less weathered and more competent with depth. The stratification boundaries indicated on the boring logs represent the approximate locations of changes in soil and rock types. In-situ, the transition of materials may be gradual and indistinct. GROUNDWATER CONDITIONS Observations were made while drilling and after completion of the borings to detect the presence and depth to hydrostatic groundwater. At the time of drilling, free water was observed across the site at an approximate depth of 26 feet below existing site grades. PVC casings were installed in the open borehole to maintain open borings and allow for additional water level measurements. Groundwater was observed at depths of approximately 21½ feet below ground surface when checked 5 days after drilling. The temporary pipes were removed and borings were backfilled upon completion of the 5- day water level measurements; subsequent groundwater measurements were not obtained. . Earth Engineering Consultants, LLC EEC Project No. 1152068 August 11, 2015 Page 4 Based on the approximate ground surface elevations at each supplemental boring location, (obtained by survey data using the finished floor elevation of the existing Perkins Restaurant), and the depth at which groundwater was recorded 5 days after drilling we developed a Groundwater Contour map included with this report. The piezometer groundwater surface flow was estimated to be in the slight northeast directions, (variations may exist across the site). Fluctuations in groundwater levels can occur over time depending on variations in hydrologic conditions, irrigation demands on and/or adjacent to the site and other conditions not apparent at the time of this report. Longer term monitoring of water levels in cased wells, which are sealed from the influence of surface water would be required to more accurately evaluate fluctuations in groundwater levels at the site. We have typically noted deepest groundwater levels in late winter and shallowest groundwater levels in mid to late summer. Zones of perched and/or trapped water can be encountered at times throughout the year in more permeable zones in the subgrade soils and perched water is commonly observed in subgrade soils immediately above lower permeability bedrock. ANALYSIS AND RECOMMENDATIONS: General Considerations and Discussion of Native Overburden Soils The subject site is generally overlain by approximately 20 to 22 feet of cohesive clay soils which extend to the fine to coarse granular soils below. Based on the previous geotechnical subsurface exploration performed on this site, the cohesive subsoils have a tendency to consolidate when inundated with water and subjected to increased loads. These soils would also show instability and strength loss when wetted and/or subjected to construction traffic loads. Final grading plans were not provided prior to the preparation of this subsurface exploration report. Based on information provided, we estimate essentially none to possibly 2 feet of fill material may be necessary within these areas to achieve final grades. The recommendations contained in this report assume that small amounts of fill will be required, and will be placed according to the recommendations provided herein. If there are any significant deviations from the assumptions concerning fill depth and/or placement when the final site plan is developed, the conclusions and recommendations of this report should be reviewed and confirmed/modified as necessary to reflect the final planned site configuration. Earth Engineering Consultants, LLC EEC Project No. 1152068 August 11, 2015 Page 5 Site Preparation We understand the existing structure on the site along with any associated site improvements will be demolished/removed from the site prior to the new building construction. In addition, all existing vegetation, tree root growth from the existing deciduous trees within the site improvement areas, topsoil, and any uncontrolled fill material that may be encountered during the excavation phases, should be removed from improvement and/or fill areas on the site. Demolition of the existing structures, concrete sidewalks, pavement and other miscellaneous features should include complete removal of all concrete or debris within the proposed construction area. Site preparation should include removal of any loose backfill found adjacent to the existing site structures/improvements. All materials derived from the demolition of the existing building, pavements, sidewalks or other site improvements should be removed from the site and not be allowed for use in any on-site fills. Although final site grades were not available at the time of this report, based on our understanding of the proposed development, we expect up to 2 feet of fill material may be necessary to achieve design grades in the improvement areas. After stripping, completing all cuts, and removing all unacceptable materials/soils, and prior to placement of any fill or site improvements, we recommend the exposed soils be scarified to a minimum depth of 9-inches, adjusted in moisture content to within ±2% of standard Proctor optimum moisture content and compacted to at least 95% of the material's standard Proctor maximum dry density as determined in accordance with ASTM Specification D698. Fill soils required for developing the building and site subgrades, after the initial zone has been prepared or stabilized where necessary, should consist of approved, low-volume-change materials, which are free from organic matter and debris. It is our opinion the on-site cohesive sandy clay soils could be used as general site fill material, provided adequate moisture treatment and compaction procedures are followed. We recommend all fill materials and foundation wall backfill materials, be placed in loose lifts not to exceed 9 inches thick and adjusted in moisture content, +/- 2% for cohesive soils and +/- 3% for cohesionless soils of optimum moisture content, and compacted to at least 98% of the materials maximum dry density as determined in accordance with ASTM Specification D698, the standard Proctor procedure. If the site’s sandy cohesive soils are used as fill material, care will be needed to maintain the recommended moisture content prior to and during construction of overlying Earth Engineering Consultants, LLC EEC Project No. 1152068 August 11, 2015 Page 6 improvements. Settlement of the backfill soils should be anticipated with total load settlement estimated on the order of 1% of the backfill height. Care should be exercised after preparation of the subgrades to avoid disturbing the subgrade materials. Positive drainage should be developed away from the structure to avoid wetting of subgrade materials. Subgrade materials becoming wet subsequent to construction of the site structure can result in unacceptable performance. Foundation Systems – General Considerations The site appears suitable for the proposed construction based on the results of our field exploration and our understanding of the proposed development plans. The following foundation system was evaluated for use on the site for the proposed building.  Straight shaft drilled piers bearing into the underlying bedrock formation. Alternative foundation systems could be considered and we would be pleased to provide additional alternatives upon request. Drilled Piers/Caissons Foundations Based on the subgrade conditions observed in the test borings and on the anticipated foundation loads, we recommend supporting the proposed building on a grade beam and straight shaft drilled pier/caisson foundation system extending into the underlying bedrock formation. Particular attention will be required in the construction of drilled piers due to the depth of bedrock and presence of groundwater. For axial compression loads, the drilled piers could be designed using a maximum end bearing pressure of 40,000 pounds per square foot (psf), along with a skin-friction of 4,000 psf for the portion of the pier extended into the underlying firm and/or harder bedrock formation. Straight shaft piers should be drilled a minimum of 10 feet into competent or harder bedrock. Lower values may be appropriate for pier “groupings” depending on the pier diameters and spacing. Pile groups should be evaluated individually. Earth Engineering Consultants, LLC EEC Project No. 1152068 August 11, 2015 Page 7 To satisfy forces in the horizontal direction, piers may be designed for lateral loads using a modulus of 50 tons per cubic foot (tcf) for the portion of the pier in native cohesive soils, 75 tcf for native granular materials or engineered fill, and 400 tcf in bedrock for a pier diameter of 12 inches. The coefficient of subgrade reaction for varying pier diameters is as follows: Pier Diameter (inches) Coefficient of Subgrade Reaction (tons/ft3) Cohesive Soils Engineered Fill or Granular Soils Bedrock 18 33 50 267 24 25 38 200 30 20 30 160 36 17 25 133 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: Parameters Native Granular Soils or Structural Fill On-Site Overburden Cohesive Soils Bedrock Unit Weight of Soil (pcf) 130(1) 115(1) 125(1) Cohesion (psf) 0 200 5000 Angle of Internal Friction () (degrees) 35 25 20 Strain Corresponding to ½ Max. Principal Stress Difference 50 --- 0.02 0.015 *Notes: 1) Reduce by 62.4 pcf below the water table Drilling caissons to design depth should be possible with conventional heavy-duty single flight power augers equipped with rock teeth on the majority of the site. However, areas of well-cemented sandstone bedrock lenses may be encountered throughout the site at various depths where specialized drilling equipment and/or rock excavating equipment may be required. Varying zones of cobbles may also be encountered in the granular soils above the bedrock. Excavation penetrating the well-cemented sandstone bedrock may require the use of specialized heavy-duty equipment, together with rock augers and/or core barrels. Consideration should be given to obtaining a unit price for difficult caisson excavation in the contract documents for the project. Earth Engineering Consultants, LLC EEC Project No. 1152068 August 11, 2015 Page 8 Due to the presence of granular soils and groundwater at approximate depths of 21 feet below site grades, maintaining shafts may be difficult without stabilizing measures. We expect temporary casing will be required to adequately/properly drill and clean piers prior to concrete placement. 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 6-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. Casing used for pier construction 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 from those presented in this report, supplemental recommendations may be required. We estimate the long-term settlement of drilled pier foundations designed and constructed as outlined above would be less than 1-inch. Seismic Site Classification The site soil conditions consist of approximately 30 feet of overburden soils overlying moderately hard to hard bedrock. The below grade parking will extend to near medium dense to dense granular soils underlain by the bedrock. For those site conditions, the 2012 International Building Code indicates a Seismic Site Classification of C. Lateral Earth Pressures The new retail/residential building will be constructed over two below grade levels of parking. The below grade walls will be subjected to unbalanced lateral earth pressures. Any site retaining walls or similar structures would also be subject to lateral soil forces. Passive lateral earth pressures may help resist the driving forces for retaining wall or other similar site structures. Earth Engineering Consultants, LLC EEC Project No. 1152068 August 11, 2015 Page 9 Active lateral earth pressures could be used for design of structures where some movement of the structure is anticipated, such as retaining walls. The total deflection of structures for design with active earth pressure is estimated to be on the order of one half of one percent of the height of the down slope side of the structure. We recommend at-rest pressures be used for design of structures where rotation of the walls is restrained, including the below grade parking structure walls. Passive pressures and friction between the footing and bearing soils could be used for design of resistance to movement of retaining walls. Coefficient values for backfill with anticipated types of soils for calculation of active, at rest and passive earth pressures are provided in the table below. Equivalent fluid pressure is equal to the coefficient times the appropriate soil unit weight. Those coefficient values are based on horizontal backfill with backfill soils consisting of essentially granular materials with a friction angle of a 30 degrees or low volume change cohesive soils. For the at-rest and active earth pressures, slopes down and away from the structure would result in reduced driving forces with slopes up and away from the structures resulting in greater forces on the walls. The passive resistance would be reduced with slopes away from the wall. The top 30-inches of soil on the passive resistance side of walls could be used as a surcharge load; however, it should not be used as a part of the passive resistance value. Frictional resistance is equal to the tangent of the friction angle times the normal force. Soil Type Low Plasticity Cohesive Medium Dense Granular Wet Unit Weight 115 135 Saturated Unit Weight 135 145 Friction Angle () – (assumed) 25° 35° Active Pressure Coefficient 0.40 0.27 At-rest Pressure Coefficient 0.58 0.42 Passive Pressure Coefficient 2.46 3.69 Surcharge loads or point loads placed in the backfill can also create additional loads on below grade walls. Those situations should be designed on an individual basis. The outlined values do not include factors of safety nor allowances for hydrostatic loads and are based on assumed friction angles, which should be verified after potential material sources have been identified. Earth Engineering Consultants, LLC EEC Project No. 1152068 August 11, 2015 Page 10 Care should be taken to develop appropriate drainage systems behind below grade walls to eliminate potential for hydrostatic loads developing on the walls. Those systems would likely include perimeter drain systems extending to sump areas or free outfall where reverse flow cannot occur into the system. Where necessary, appropriate hydrostatic load values should be used for design. Parking Garage Slab-on-Grade Based on the materials observed in the soil borings, it is our opinion the building basement floor slab could be directly supported by the in-place stiff cohesive soils or underlying in-situ granular materials. A granular leveling course could be used, if needed. Under slab vapor barrier should be used at the architect’s discretion. The in-situ soils at basement level would likely show instability under construction traffic. Rutting, potentially significant rutting, may occur under heavier loads associated with drilling equipment for the caisson drilling. Construction of a stabilized mat may be needed to accommodate the construction traffic. A crushed granular material may be considered for the stabilized mat zone. After completion of the caissons, a finer granular zone could be placed over the stabilized material to support the floor slab. Additional floor slab design and construction recommendations are as follows:  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 a similar manner as previously described for imported structural fill material.  Floor slabs should not be constructed on frozen subgrade.  Other design and construction considerations, as outlined in the ACI Design Manual, Section 302.1R are recommended. Underslab and Perimeter Drainage Systems We understand the below grade parking will extend to a depth of approximately 16 feet below present surface grades. The subsurface soils encountered in the test borings completed for this Earth Engineering Consultants, LLC EEC Project No. 1152068 August 11, 2015 Page 11 project included approximately 20 to 22 feet of sandy lean clay overlying sands and gravels which were underlain by weathered bedrock. The test borings encountered groundwater at depths on the order of 21 feet below present site grades. However, some fluctuation can occur in groundwater depths depending on variations in hydrologic conditions and other conditions not apparent at the time of this report. At a depth of approximately 16 feet below existing ground surface, the bottom of the basement walls for the structure are expected to terminate in sandy lean clay subgrade soils. The structure will be supported on drilled pier foundations extending to the underlying bedrock. With potential infiltration of surface water adjacent to the building, we anticipate water could accumulate next to the below grade walls and result in hydrostatic loading on those walls and, potentially, infiltration of the surface water into the below grade areas. We suggest a perimeter drain system be installed to remove surface infiltration water from the area adjacent to the below grade walls and reduce the likelihood of development of hydrostatic loads on the walls and/or water infiltration into the below grade area. In general, a perimeter drain system would consist of perforated metal or plastic pipe placed at the approximate bottom of basement wall elevation and sloped to drain to a sump area where accumulated water can be removed without reverse flow into the system. The drain line should be surrounded by at least 6 inches of free draining granular fill with either the drain line or granular fill wrapped in an appropriate filter fabric to prevent the intrusions of fines in the system. Backfill above the drain line should consist of approved, low volume change material. The basement floor will be on the order of 5 feet or greater above the groundwater measurements recorded at the time of our exploration. The previous exploration on this site indicated groundwater at the approximate depth as measured on this project. However, some fluctuations in groundwater levels can occur over time depending on variations in hydrologic conditions and other conditions not apparent at the time of this report. Consideration could be given to installation of an underslab drain system to reduce the potential for groundwater level rises to exert uplift pressures on the floor slabs and/or infiltrate into below grade areas. An underslab drain system would consist of an approximate 6-inch thick blanket of free draining granular fill immediately beneath the basement floor slab with perforated drain line installed in minimum 6-inch deep trenches at approximately 10-foot intervals across the width of the building. An interior perimeter drain should be installed extending around the interior perimeter of the building grade beam. Drain lines should allow for flow of water to a sump area without reverse of flow into the system. The subgrade between the drain lines should be sloped to drain towards each Earth Engineering Consultants, LLC EEC Project No. 1152068 August 11, 2015 Page 12 of the drain lines. The sandy lean clay subgrades should be separated from the overlying free draining granular fill with a filter fabric to prevent infiltration of fines into the system. Installation of the drain systems will reduce, not eliminate, the potential for infiltration of surface and/or groundwater into the below grade areas and development of hydrostatic loads on structure components. Pumps and other components require periodic inspections and maintenance to maintain the system in functioning condition. Water Soluble Sulfates (SO4) The water soluble sulfate (SO4) testing of the on-site overburden and bedrock materials taken during our subsurface exploration at varying depths are provided in the table below. Based on the reported sulfate content test results, this report includes a recommendation for the CLASS or TYPE of cement for use for contact in association with the on-site bedrock. TABLE IV - Water Soluble Sulfate Test Results Sample Location Description Soluble Sulfate Content (mg/kg) Soluble Sulfate Content (%) B-5 S-2 @ 29’ Sandstone Bedrock 120 0.01 B-7, S-1 @ 19’ Silty Sand with Gravel 130 0.01 Based on the results as presented in the table above, ACI 318, Section 4.2 indicates the site overburden soils and/or bedrock generally have a low risk of sulfate attack on Portland cement concrete. Therefore Class 0 and Type I or Type I/II cement could be used for concrete on and below site grade within the overburden soils and/or bedrock. Foundation concrete should be designed in accordance with the provisions of the ACI Design Manual, Section 318, Chapter 4. These results are being compared to the following table. Table V - Requirements to Protect Against Damage to Concrete by Sulfate Attack from External Sources of Sulfate Severity of Sulfate exposure Water-soluble sulfate (SO4) in dry soil, percent Water-cement ratio, maximum Cementitious material Requirements Class 0 0.00 to 0.10% 0.45 Class 0 Class 1 0.11 to 0.20% 0.45 Class 1 Class 2 0.21 to 2.00% 0.45 Class 2 Class 3 2.01 of greater 0.45 Class 3 Earth Engineering Consultants, LLC EEC Project No. 1152068 August 11, 2015 Page 13 Other Considerations Positive drainage should be developed away from the structure with a minimum slope of 1-inch per foot for the first 10-feet away from the improvements in landscape areas. Flatter slopes could be used in hardscapes areas although positive drainage should be maintained. Care should be taken in planning of landscaping adjacent to the building and parking and drive areas to avoid features which would pond water adjacent to the pavement, foundations or stemwalls. Placement of plants which require irrigation systems or could result in fluctuations of the moisture content of the subgrade material should be avoided adjacent to site improvements. Excavations into the on-site soils may encounter a variety of conditions. Excavations into the on- site clays can be expected to stand on relatively steep temporary slopes during construction. However, if excavations extend into the underlying granular strata, caving soils may 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. Depending upon the depth of any lower level construction, a shoring plan will be necessary to protect the adjacent sidewall slopes. The project design team should use the subsurface information provided herein to properly design a mechanism for shoring protection. EEC is available to provide supplemental design criteria or details such as but not limited to secant piles or piers, soldier piers, or a tie-back/bracing concept. GENERAL COMMENTS The analysis and recommendations presented in this report are based upon the data obtained from the soil borings performed at the indicated locations and from any other information discussed in this report. This report does not reflect any variations, which may occur between borings or across the site. The nature and extent of such variations may not become evident until construction. If variations appear evident, it will be necessary to re-evaluate the recommendations of this report. It is recommended that the geotechnical engineer be retained to review the plans and specifications so comments can be made regarding the interpretation and implementation of our geotechnical recommendations in the design and specifications. It is further recommended that the geotechnical Earth Engineering Consultants, LLC EEC Project No. 1152068 August 11, 2015 Page 14 engineer be retained for testing and observations during earthwork phases to help determine that the design requirements are fulfilled. Site-specific explorations should be completed to develop site- specific recommendations for each of the site buildings. This report has been prepared for the exclusive use for CA Ventures for specific application to the project discussed and has been prepared in accordance with generally accepted geotechnical engineering practices. No warranty, express or implied, is made. In the event that any 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 the changes are reviewed and the conclusions of this report are modified or verified in writing by the geotechnical engineer. Earth Engineering Consultants, LLC DRILLING AND EXPLORATION DRILLING & SAMPLING SYMBOLS: SS: Split Spoon ‐ 13/8" I.D., 2" O.D., unless otherwise noted PS: Piston Sample ST: Thin‐Walled Tube ‐ 2" O.D., unless otherwise noted WS: Wash Sample R: Ring Barrel Sampler ‐ 2.42" I.D., 3" O.D. unless otherwise noted PA: Power Auger FT: Fish Tail Bit HA: Hand Auger RB: Rock Bit DB: Diamond Bit = 4", N, B BS: Bulk Sample AS: Auger Sample PM: Pressure Meter HS: Hollow Stem Auger WB: Wash Bore Standard "N" Penetration: Blows per foot of a 140 pound hammer falling 30 inches on a 2‐inch O.D. split spoon, except where noted. WATER LEVEL MEASUREMENT SYMBOLS: WL : Water Level WS : While Sampling WCI: Wet Cave in WD : While Drilling DCI: Dry Cave in BCR: Before Casing Removal AB : After Boring ACR: After Casting Removal Water levels indicated on the boring logs are the levels measured in the borings at the time indicated. In pervious soils, the indicated levels may reflect the location of ground water. In low permeability soils, the accurate determination of ground water levels is not possible with only short term observations. DESCRIPTIVE SOIL CLASSIFICATION Soil Classification is based on the Unified Soil Classification system and the ASTM Designations D‐2488. Coarse Grained Soils have move than 50% of their dry weight retained on a #200 sieve; they are described as: boulders, cobbles, gravel or sand. Fine Grained Soils have less than 50% of their dry weight retained on a #200 sieve; they are described as : clays, if they are plastic, and silts if they are slightly plastic or non‐plastic. Major constituents may be added as modifiers and minor constituents may be added according to the relative proportions based on grain size. In addition to gradation, coarse grained soils are defined on the basis of their relative in‐ place density and fine grained soils on the basis of their consistency. Example: Lean clay with sand, trace gravel, stiff (CL); silty sand, trace gravel, medium dense (SM). CONSISTENCY OF FINE‐GRAINED SOILS Unconfined Compressive Strength, Qu, psf Consistency < 500 Very Soft 500 ‐ 1,000 Soft 1,001 ‐ 2,000 Medium 2,001 ‐ 4,000 Stiff 4,001 ‐ 8,000 Very Stiff 8,001 ‐ 16,000 Very Hard RELATIVE DENSITY OF COARSE‐GRAINED SOILS: N‐Blows/ft Relative Density 0‐3 Very Loose 4‐9 Loose 10‐29 Medium Dense 30‐49 Dense 50‐80 Very Dense 80 + Extremely Dense PHYSICAL PROPERTIES OF BEDROCK DEGREE OF WEATHERING: Slight Slight decomposition of parent material on joints. May be color change. Moderate Some decomposition and color change throughout. High Rock highly decomposed, may be extremely broken. Group Symbol Group Name Cu≥4 and 1<Cc≤3 E GW Well-graded gravel F Cu<4 and/or 1>Cc>3 E GP Poorly-graded gravel F Fines classify as ML or MH GM Silty gravel G,H Fines Classify as CL or CH GC Clayey Gravel F,G,H Cu≥6 and 1<Cc≤3 E SW Well-graded sand I Cu<6 and/or 1>Cc>3 E SP Poorly-graded sand I Fines classify as ML or MH SM Silty sand G,H,I Fines classify as CL or CH SC Clayey sand G,H,I inorganic PI>7 and plots on or above "A" Line CL Lean clay K,L,M PI<4 or plots below "A" Line ML Silt K,L,M organic Liquid Limit - oven dried Organic clay K,L,M,N Liquid Limit - not dried Organic silt K,L,M,O inorganic PI plots on or above "A" Line CH Fat clay K,L,M PI plots below "A" Line MH Elastic Silt K,L,M organic Liquid Limit - oven dried Organic clay K,L,M,P Liquid Limit - not dried Organic silt K,L,M,O Highly organic soils PT Peat (D30)2 D10 x D60 GW-GM well graded gravel with silt NPI≥4 and plots on or above "A" line. GW-GC well-graded gravel with clay OPI≤4 or plots below "A" line. GP-GM poorly-graded gravel with silt PPI plots on or above "A" line. GP-GC poorly-graded gravel with clay QPI plots below "A" line. SW-SM well-graded sand with silt SW-SC well-graded sand with clay SP-SM poorly graded sand with silt SP-SC poorly graded sand with clay Earth Engineering Consultants, LLC IIf soil contains >15% gravel, add "with gravel" to group name JIf Atterberg limits plots shaded area, soil is a CL- ML, Silty clay Unified Soil Classification System B-7 B-6 B-5 B-8 Boring Location Diagram CA Ventures - Student Housing Project Fort Collins, Colorado EEC Project Number: 1152068 Date: July 2015 EARTH ENGINEERING CONSULTANTS, LLC Approximate Boring Locations Legend B-7 B-6 B-5 B-8 [4993.0] (4971.6) [4992.5] (4971.5) [4933.8] (4972.4) [4993.6] (4972.1) 4972.5 4972.0 4971.5 Figure 2: Groundwater Contour Map 300-310 South College Ave Fort Collins, Colorado EEC Project Number: 1152068 Date: July 2015 EARTH ENGINEERING CONSULTANTS, LLC Approximate Boring Locations Legend Approximate Ground Surface Elevation at Each Boring Based on Linear Interpolation of Contours on Topographic Map Provided by Client Approximate Groundwater Elevations [4890] (4890) Estimated Groundwater Contours Based on Linear Interpolations Between Borings. Actual Conditions May Vary Estimated Direction of Flow DATE: RIG TYPE: CME-75 FOREMAN: JS AUGER TYPE: 4-1/4" Hollow Stem Augers SPT HAMMER: MANUAL SOIL DESCRIPTION D N QU MC DD -200 TYPE (FEET) (BLOWS/FT) (PSF) (%) (PCF) LL PI (%) PRESSURE % @ 500 PSF EXISTING ASPHALT (HMA) - Approx. 3.5" _ _ EXISTING ABC - Approx. 6" 1 _ _ FILL MATERIAL: Silty Sand with Gravel / Clayey Sand 2 with Gravel _ _ reddish brown, moist, medium dense 3 _ _ 4 _ _ 5 LEAN CLAY with SAND (CL) / SANDY LEAN CLAY (CL) _ _ brown, moist, medium stiff to stiff 6 _ _ 7 _ _ 8 _ _ 9 _ _ 10 _ _ 11 _ _ 12 _ _ 13 _ _ 14 _ _ 15 _ _ 16 _ _ 17 _ _ 18 _ _ 19 SILTY SAND with GRAVEL (SW-SM) _ _ tan, gray, moist to wet, SS 20 50/9" -- 1.7 dense to very dense _ _ 21 _ _ 22 _ _ 23 _ _ 24 _ _ SS 25 Continued on Sheet 2 of 2 _ _ Earth Engineering Consultants 310 SOUTH COLLEGE AVENUE - Multi-Level Mixed Use Development DATE: RIG TYPE: CME-75 FOREMAN: JS AUGER TYPE: 4-1/4" Hollow Stem Augers SPT HAMMER: MANUAL SOIL DESCRIPTION D N QU MC DD -200 TYPE (FEET) (BLOWS/FT) (PSF) (%) (PCF) LL PI (%) PRESSURE % @ 500 PSF Continued from Sheet 1 of 2 26 _ _ SILTY SAND with GRAVEL (SW-SM) 27 tan, gray, moist to wet, _ _ dense to very dense 28 _ _ 29 _ _ SANDSTONE BEDROCK, SS 30 50/3" -- 9.9 brown / grey / rust _ _ poorly cemented to cemented 31 _ _ 32 _ _ 33 _ _ 34 _ _ 35 _ _ 36 _ _ 37 _ _ 38 _ _ 39 _ _ 40 50/2" -- 16.3 _ _ BOTTOM OF BORING DEPTH @ 39.2' 41 _ _ 42 _ _ 43 _ _ 44 _ _ 45 _ _ 46 _ _ 47 _ _ 48 _ _ 49 _ _ 50 _ _ Earth Engineering Consultants 310 SOUTH COLLEGE AVENUE - Multi-Level Mixed Use Development FORT COLLINS, COLORADO DATE: RIG TYPE: CME-75 FOREMAN: JS AUGER TYPE: 4-1/4" Hollow Stem Augers SPT HAMMER: MANUAL SOIL DESCRIPTION D N QU MC DD -200 TYPE (FEET) (BLOWS/FT) (PSF) (%) (PCF) LL PI (%) PRESSURE % @ 500 PSF EXISTING ASPHALT (HMA) - Approx. 3.5" _ _ EXISTING ABC - Approx. 6" 1 _ _ FILL MATERIAL: Silty Sand with Gravel / Clayey Sand 2 with Gravel _ _ reddish brown, moist, medium dense 3 _ _ 4 _ _ 5 LEAN CLAY with SAND (CL) / SANDY LEAN CLAY (CL) _ _ brown, moist, medium stiff to stiff 6 _ _ 7 _ _ 8 _ _ 9 _ _ 10 _ _ 11 _ _ 12 _ _ 13 _ _ 14 _ _ 15 _ _ 16 _ _ 17 _ _ 18 _ _ 19 _ _ SS 20 43 5000 11.5 SILTY SAND with GRAVEL (SW-SM) _ _ tan, gray, moist to wet, 21 dense to very dense _ _ 22 _ _ 23 _ _ 24 _ _ SS 25 Continued on Sheet 2 of 2 _ _ Earth Engineering Consultants 310 SOUTH COLLEGE AVENUE - Multi-Level Mixed Use Development DATE: RIG TYPE: CME-75 FOREMAN: JS AUGER TYPE: 4-1/4" Hollow Stem Augers SPT HAMMER: MANUAL SOIL DESCRIPTION D N QU MC DD -200 TYPE (FEET) (BLOWS/FT) (PSF) (%) (PCF) LL PI (%) PRESSURE % @ 500 PSF Continued from Sheet 1 of 2 26 _ _ SILTY SAND with GRAVEL (SW-SM) 27 tan, gray, moist to wet, _ _ dense to very dense 28 _ _ 29 _ _ SANDSTONE BEDROCK, SS 30 50/3" 5000 18.4 brown / grey / rust _ _ poorly cemented to cemented 31 _ _ 32 _ _ 33 _ _ 34 _ _ 35 _ _ 36 _ _ 37 _ _ 38 _ _ 39 _ _ 40 50/1" -- 19.6 _ _ BOTTOM OF BORING DEPTH @ 39.2' 41 _ _ 42 _ _ 43 _ _ 44 _ _ 45 _ _ 46 _ _ 47 _ _ 48 _ _ 49 _ _ 50 _ _ Earth Engineering Consultants 310 SOUTH COLLEGE AVENUE - Multi-Level Mixed Use Development FORT COLLINS, COLORADO DATE: RIG TYPE: CME-75 FOREMAN: JS AUGER TYPE: 4-1/4" Hollow Stem Augers SPT HAMMER: MANUAL SOIL DESCRIPTION D N QU MC DD -200 TYPE (FEET) (BLOWS/FT) (PSF) (%) (PCF) LL PI (%) PRESSURE % @ 500 PSF EXISTING ASPHALT (HMA) - Approx. 3.5" _ _ EXISTING ABC - Approx. 6" 1 _ _ FILL MATERIAL: Silty Sand with Gravel / Clayey Sand 2 with Gravel _ _ reddish brown, moist, medium dense 3 _ _ 4 _ _ 5 LEAN CLAY with SAND (CL) / SANDY LEAN CLAY (CL) _ _ brown, moist, medium stiff to stiff 6 _ _ 7 _ _ 8 _ _ 9 _ _ 10 _ _ 11 _ _ 12 _ _ 13 _ _ 14 _ _ 15 _ _ 16 _ _ 17 _ _ 18 _ _ 19 SILTY SAND with GRAVEL (SW-SM) _ _ tan, gray, moist to wet, SS 20 50/9" -- 2.0 dense to very dense _ _ 21 _ _ 22 _ _ 23 _ _ 24 _ _ SS 25 Continued on Sheet 2 of 2 _ _ Earth Engineering Consultants 310 SOUTH COLLEGE AVENUE - Multi-Level Mixed Use Development DATE: RIG TYPE: CME-75 FOREMAN: JS AUGER TYPE: 4-1/4" Hollow Stem Augers SPT HAMMER: MANUAL SOIL DESCRIPTION D N QU MC DD -200 TYPE (FEET) (BLOWS/FT) (PSF) (%) (PCF) LL PI (%) PRESSURE % @ 500 PSF Continued from Sheet 1 of 2 26 _ _ SILTY SAND with GRAVEL (SW-SM) 27 tan, gray, moist to wet, _ _ dense to very dense 28 _ _ 29 _ _ SANDSTONE BEDROCK, SS 30 50/4" 5000 17.9 brown / grey / rust _ _ poorly cemented to cemented 31 _ _ 32 _ _ 33 _ _ 34 _ _ 35 _ _ 36 _ _ 37 _ _ 38 _ _ 39 _ _ 40 50/2" 5000 17.3 _ _ BOTTOM OF BORING DEPTH @ 39.2' 41 _ _ 42 _ _ 43 _ _ 44 _ _ 45 _ _ 46 _ _ 47 _ _ 48 _ _ 49 _ _ 50 _ _ Earth Engineering Consultants 310 SOUTH COLLEGE AVENUE - Multi-Level Mixed Use Development FORT COLLINS, COLORADO DATE: RIG TYPE: CME-75 FOREMAN: JS AUGER TYPE: 4-1/4" Hollow Stem Augers SPT HAMMER: MANUAL SOIL DESCRIPTION D N QU MC DD -200 TYPE (FEET) (BLOWS/FT) (PSF) (%) (PCF) LL PI (%) PRESSURE % @ 500 PSF EXISTING ASPHALT (HMA) - Approx. 3.5" _ _ EXISTING ABC - Approx. 6" 1 _ _ FILL MATERIAL: Silty Sand with Gravel / Clayey Sand 2 with Gravel _ _ reddish brown, moist, medium dense 3 _ _ 4 _ _ 5 LEAN CLAY with SAND (CL) / SANDY LEAN CLAY (CL) _ _ brown, moist, medium stiff to stiff 6 _ _ 7 _ _ 8 _ _ 9 _ _ 10 _ _ 11 _ _ 12 _ _ 13 _ _ 14 _ _ 15 _ _ 16 _ _ 17 _ _ 18 _ _ 19 _ _ SS 20 50/9" 7500 6.6 SILTY SAND with GRAVEL (SW-SM) _ _ tan, gray, moist to wet, 21 dense to very dense _ _ 22 _ _ 23 _ _ 24 _ _ SS 25 Continued on Sheet 2 of 2 _ _ Earth Engineering Consultants 310 SOUTH COLLEGE AVENUE - Multi-Level Mixed Use Development DATE: RIG TYPE: CME-75 FOREMAN: JS AUGER TYPE: 4-1/4" Hollow Stem Augers SPT HAMMER: MANUAL SOIL DESCRIPTION D N QU MC DD -200 TYPE (FEET) (BLOWS/FT) (PSF) (%) (PCF) LL PI (%) PRESSURE % @ 500 PSF Continued from Sheet 1 of 2 26 _ _ SILTY SAND with GRAVEL (SW-SM) 27 tan, gray, moist to wet, _ _ dense to very dense 28 _ _ 29 _ _ SANDSTONE BEDROCK, SS 30 50/3" -- 16.5 brown / grey / rust _ _ poorly cemented to cemented 31 _ _ 32 _ _ 33 _ _ 34 _ _ 35 _ _ 36 _ _ 37 _ _ 38 _ _ 39 _ _ 40 50/2" -- 19.2 _ _ BOTTOM OF BORING DEPTH @ 39.2' 41 _ _ 42 _ _ 43 _ _ 44 _ _ 45 _ _ 46 _ _ 47 _ _ 48 _ _ 49 _ _ 50 _ _ Earth Engineering Consultants 310 SOUTH COLLEGE AVENUE - Multi-Level Mixed Use Development FORT COLLINS, COLORADO 1 1/2" (37.5 mm) 1" (25 mm) 3/4" (19 mm) 1/2" (12.5 mm) 3/8" (9.5 mm) No. 4 (4.75 mm) No. 8 (2.36 mm) No. 10 (2 mm) No. 16 (1.18 mm) No. 30 (0.6 mm) No. 40 (0.425 mm) No. 50 (0.3 mm) No. 100 (0.15 mm) No. 200 (0.075 mm) Project: 310 S College Ave Location: Fort Collins, Colorado Project No: 1152068 Sample ID: B5, S1, 19 Sample Desc.: Tan / Gray Silty Sand with Gravel (SW-SM) Date: July 2015 27 23 19 13 8.8 79 68 55 50 38 100 100 87 83 EARTH ENGINEERING CONSULTANTS, LLC SUMMARY OF LABORATORY TEST RESULTS Sieve Analysis (AASHTO T 11 & T 27 / ASTM C 117 & C 136) Sieve Size Percent Passing Gravel Coarse Fine Sand Coarse Medium Fine EARTH ENGINEERING CONSULTANTS, LLC Summary of Washed Sieve Analysis Tests (ASTM C117 & C136) Date: 310 S College Ave Fort Collins, Colorado 1152068 B5, S1, 19 Tan / Gray Silty Sand with Gravel (SW-SM) July 2015 Project: Location: Project No: Sample ID: Sample Desc.: Cobble Silt or Clay 6" 5" 4" 3" 2.5" 2" 1.5" 1" 3/4" 1/2" 3/8" No. 4 No. 8 No. 10 No. 16 No. 30 No. 40 No. 50 No. 100 No. 200 0 10 20 30 40 50 60 70 80 90 100 1000 100 10 1 0.1 0.01 Finer by Weight (%) Grain Size (mm) Standard Sieve Size 1 1/2" (37.5 mm) 1" (25 mm) 3/4" (19 mm) 1/2" (12.5 mm) 3/8" (9.5 mm) No. 4 (4.75 mm) No. 8 (2.36 mm) No. 10 (2 mm) No. 16 (1.18 mm) No. 30 (0.6 mm) No. 40 (0.425 mm) No. 50 (0.3 mm) No. 100 (0.15 mm) No. 200 (0.075 mm) Project: 310 S College Ave Location: Fort Collins, Colorado Project No: 1152068 Sample ID: B6, S1, 19 Sample Desc.: Tan / Gray Silty Sand with Gravel (SW-SM) Date: July 2015 58 55 53 50 47.1 82 73 68 67 63 100 100 100 86 EARTH ENGINEERING CONSULTANTS, LLC SUMMARY OF LABORATORY TEST RESULTS Sieve Analysis (AASHTO T 11 & T 27 / ASTM C 117 & C 136) Sieve Size Percent Passing Gravel Coarse Fine Sand Coarse Medium Fine EARTH ENGINEERING CONSULTANTS, LLC Summary of Washed Sieve Analysis Tests (ASTM C117 & C136) Date: 310 S College Ave Fort Collins, Colorado 1152068 B6, S1, 19 Tan / Gray Silty Sand with Gravel (SW-SM) July 2015 Project: Location: Project No: Sample ID: Sample Desc.: Cobble Silt or Clay 6" 5" 4" 3" 2.5" 2" 1.5" 1" 3/4" 1/2" 3/8" No. 4 No. 8 No. 10 No. 16 No. 30 No. 40 No. 50 No. 100 No. 200 0 10 20 30 40 50 60 70 80 90 100 1000 100 10 1 0.1 0.01 Finer by Weight (%) Grain Size (mm) Standard Sieve Size 1 1/2" (37.5 mm) 1" (25 mm) 3/4" (19 mm) 1/2" (12.5 mm) 3/8" (9.5 mm) No. 4 (4.75 mm) No. 8 (2.36 mm) No. 10 (2 mm) No. 16 (1.18 mm) No. 30 (0.6 mm) No. 40 (0.425 mm) No. 50 (0.3 mm) No. 100 (0.15 mm) No. 200 (0.075 mm) Project: 310 S College Ave Location: Fort Collins, Colorado Project No: 1152068 Sample ID: B8, S1, 19 Sample Desc.: Tan / Gray Silty Sand with Gravel (SW-SM) Date: July 2015 38 36 34 30 27.1 57 51 45 44 41 100 75 65 60 EARTH ENGINEERING CONSULTANTS, LLC SUMMARY OF LABORATORY TEST RESULTS Sieve Analysis (AASHTO T 11 & T 27 / ASTM C 117 & C 136) Sieve Size Percent Passing Gravel Coarse Fine Sand Coarse Medium Fine EARTH ENGINEERING CONSULTANTS, LLC Summary of Washed Sieve Analysis Tests (ASTM C117 & C136) Date: 310 S College Ave Fort Collins, Colorado 1152068 B8, S1, 19 Tan / Gray Silty Sand with Gravel (SW-SM) July 2015 Project: Location: Project No: Sample ID: Sample Desc.: Cobble Silt or Clay 6" 5" 4" 3" 2.5" 2" 1.5" 1" 3/4" 1/2" 3/8" No. 4 No. 8 No. 10 No. 16 No. 30 No. 40 No. 50 No. 100 No. 200 0 10 20 30 40 50 60 70 80 90 100 1000 100 10 1 0.1 0.01 Finer by Weight (%) Grain Size (mm) Standard Sieve Size PROJECT NO: 1152068 JULY 2015 LOG OF BORING B-8 SHEET 2 OF 2 WATER DEPTH START DATE 7/1/2015 WHILE DRILLING 26.0' FINISH DATE 7/1/2015 AFTER DRILLING N/A APPROX. SURFACE ELEV 4993.6 SS When Checked 5 days 21.5' A-LIMITS SWELL FORT COLLINS, COLORADO PROJECT NO: 1152068 JULY 2015 LOG OF BORING B-8 SHEET 1 OF 2 WATER DEPTH START DATE 7/1/2015 WHILE DRILLING 26.0' FINISH DATE 7/1/2015 AFTER DRILLING N/A APPROX. SURFACE ELEV 4993.6 When Checked 5 days 21.5' A-LIMITS SWELL PROJECT NO: 1152068 JULY 2015 LOG OF BORING B-7 SHEET 2 OF 2 WATER DEPTH START DATE 7/1/2015 WHILE DRILLING 26.0' FINISH DATE 7/1/2015 AFTER DRILLING N/A APPROX. SURFACE ELEV 4992.5 SS When Checked 5 days 21.0' A-LIMITS SWELL FORT COLLINS, COLORADO PROJECT NO: 1152068 JULY 2015 LOG OF BORING B-7 SHEET 1 OF 2 WATER DEPTH START DATE 7/1/2015 WHILE DRILLING 26.0' FINISH DATE 7/1/2015 AFTER DRILLING N/A APPROX. SURFACE ELEV 4992.5 When Checked 5 days 21.0' A-LIMITS SWELL PROJECT NO: 1152068 JULY 2015 LOG OF BORING B-6 SHEET 2 OF 2 WATER DEPTH START DATE 7/1/2015 WHILE DRILLING 26.0' FINISH DATE 7/1/2015 AFTER DRILLING N/A APPROX. SURFACE ELEV 4993.8 SS When Checked 5 days 21.4 A-LIMITS SWELL FORT COLLINS, COLORADO PROJECT NO: 1152068 JULY 2015 LOG OF BORING B-6 SHEET 1 OF 2 WATER DEPTH START DATE 7/1/2015 WHILE DRILLING 26.0' FINISH DATE 7/1/2015 AFTER DRILLING N/A APPROX. SURFACE ELEV 4993.8 When Checked 5 days 21.4 A-LIMITS SWELL PROJECT NO: 1152068 JULY 2015 LOG OF BORING B-5 SHEET 2 OF 2 WATER DEPTH START DATE 7/1/2015 WHILE DRILLING 26.0' FINISH DATE 7/1/2015 AFTER DRILLING N/A APPROX. SURFACE ELEV 4993 SS When Checked 5 days 21.3' A-LIMITS SWELL FORT COLLINS, COLORADO PROJECT NO: 1152068 JULY 2015 LOG OF BORING B-5 SHEET 1 OF 2 WATER DEPTH START DATE 7/1/2015 WHILE DRILLING 26.0' FINISH DATE 7/1/2015 AFTER DRILLING N/A APPROX. SURFACE ELEV 4993.0 When Checked 5 days 21.3' A-LIMITS SWELL Soil Classification Criteria for Assigning Group Symbols and Group Names Using Laboratory Tests Sands 50% or more coarse fraction passes No. 4 sieve Fine-Grained Soils 50% or more passes the No. 200 sieve <0.75 OL Gravels with Fines more than 12% fines Clean Sands Less than 5% fines Sands with Fines more than 12% fines Clean Gravels Less than 5% fines Gravels more than 50% of coarse fraction retained on No. 4 sieve Coarse - Grained Soils more than 50% retained on No. 200 sieve CGravels with 5 to 12% fines required dual symbols: Kif soil contains 15 to 29% plus No. 200, add "with sand" or "with gravel", whichever is predominant. <0.75 OH Primarily organic matter, dark in color, and organic odor ABased on the material passing the 3-in. (75-mm) sieve ECu=D60/D10 Cc= HIf fines are organic, add "with organic fines" to group name LIf soil contains ≥ 30% plus No. 200 predominantly sand, add "sandy" to group name. MIf soil contains ≥30% plus No. 200 predominantly gravel, add "gravelly" to group name. DSands with 5 to 12% fines require dual symbols: BIf field sample contained cobbles or boulders, or both, add "with cobbles or boulders, or both" to group name. FIf soil contains ≥15% sand, add "with sand" to GIf fines classify as CL-ML, use dual symbol GC- CM, or SC-SM. Silts and Clays Liquid Limit less than 50 Silts and Clays Liquid Limit 50 or more 0 10 20 30 40 50 60 0 10 20 30 40 50 60 70 80 90 100 110 PLASTICITY INDEX (PI) LIQUID LIMIT (LL) ML OR OL MH OR OH For Classification of fine-grained soils and fine-grained fraction of coarse-grained soils. Equation of "A"-line Horizontal at PI=4 to LL=25.5 then PI-0.73 (LL-20) Equation of "U"-line Vertical at LL=16 to PI-7, then PI=0.9 (LL-8) CL-ML HARDNESS AND DEGREE OF CEMENTATION: Limestone and Dolomite: Hard Difficult to scratch with knife. Moderately Can be scratched easily with knife. Hard Cannot be scratched with fingernail. Soft Can be scratched with fingernail. Shale, Siltstone and Claystone: Hard Can be scratched easily with knife, cannot be scratched with fingernail. Moderately Can be scratched with fingernail. Hard Soft Can be easily dented but not molded with fingers. Sandstone and Conglomerate: Well Capable of scratching a knife blade. Cemented Cemented Can be scratched with knife. Poorly Can be broken apart easily with fingers. Cemented