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HomeMy WebLinkAbout2590 MIDPOINT DRIVE - PDP - PDP160010 - SUBMITTAL DOCUMENTS - ROUND 1 - GEOTECHNICAL (SOILS) REPORTGEOTECHNICAL SUBSURFACE EXPLORATION REPORT LOT 18 MIDPOINT DEVELOPMENT THUNDERPUP CONSTRUCTION FORT COLLINS, COLORADO EEC PROJECT NO. 1142088A Prepared for: Thunderpup Construction, Inc. 309 S. Link Lane Fort Collins, Colorado 80524 Attention: Mr. Steve Wimp (steve@thunderpup.com) Prepared by: Earth Engineering Consultants, LLC 4396 Greenfield Drive Windsor, Colorado 80550 4396 GREENFIELD DRIVE WINDSOR, COLORADO 80550 (970) 224-1522 FAX (970) 663-0282 January 6, 2015 Thunderpup Construction, Inc. 309 S. Link Lane Fort Collins, CO 80524 Attn: Mr. Steve Wimp (steve@thunderpup.com) Re: Geotechnical Exploration Report Lot 18 Midpoint Development Thunderpup Construction Fort Collins, Colorado EEC Project No. 1142088A Mr. Wimp: Enclosed, herewith, are the results of the geotechnical subsurface exploration you requested for the proposed office building planned to be constructed on Lot 18 of the Midpoint Development property in Fort Collins, Colorado. In summary, the subsurface soils encountered in the test borings consist of brown sandy lean clay / clayey sand underlain by poorly graded sands and gravels. The near surface clays were moderately plastic, relatively dry and subject to swelling with increased moisture at current moisture and density. The poorly graded sands and gravels were encountered approximately 7 to 8 feet below existing grade and were medium dense to dense in consistency. Groundwater was observed approximately 9 to 10 feet below ground surface. Based on the soils observed at the test boring locations, it is our opinion the proposed structure could be supported on conventional footing foundations bearing on a layer of reconditioned site lean clay soils. Reconditioning of a minimum of 3 feet of the in-place subgrade soils beneath the floors should be completed to reduce post-construction heaving. Lightly loaded exterior flatwork and/or pavements supported on the near surface clays would be expected to heave with expansion of the dry clay subgrades. Reconditioning of a defined thickness of subgrades below pavements and flatwork could be considered to reduce total and differential movement; however, some movement of the pavements and flatwork should still be expected. Geotechnical recommendations concerning design and construction of footing foundations, support of the building floor GEOTECHNICAL EXPLORATION REPORT LOT 18 MIDPOINT DEVELOPMENT THUNDERPUP CONSTRUCTION, INC. FORT COLLINS, COLORADO EEC PROJECT NO. 1142088A January 6, 2015 INTRODUCTION The subsurface exploration for the proposed building to be constructed on Lot 18 of the Midpoint Development property in Fort Collins, Colorado, has been completed. Three (3) soil borings were completed within the development lot to obtain information on existing subsurface conditions. The borings were extended to depths of approximately 10 to 25 feet below present site grades. Individual boring logs and a diagram indicating the approximate boring locations are provided with this report. We understand the proposed structure will be a single-story, slab-on-grade (non-basement) pre-engineered metal framed building with a total plan area of approximately 7,000 square feet. Foundation loads for the structure are expected to be light with continuous wall loads less than 3 kips per lineal foot and individual column loads less than 50 kips. We understand drive and parking areas will be constructed adjacent to the building. It is our understanding small cuts and fills will be required to develop finished grade for the site. The purpose of this report is to describe the subsurface conditions encountered in the borings, analyze and evaluate the test data and provide geotechnical recommendations concerning design and construction of the foundations and support of floor slabs, exterior flatwork and pavements. EXPLORATION AND TESTING PROCEDURES The boring locations were determined and established in the field by representatives of Earth Engineering Consultants, LLC (EEC) by pacing and estimating angles from identifiable site features. The locations of the borings should be considered accurate only to the degree implied by the methods used to make the field measurements. Earth Engineering Consultants, LLC EEC Project No. 1142088A January 6, 2015 Page 2 The borings were performed using a truck mounted, CME-55 drill rig equipped with a hydraulic head employed in drilling and sampling operations. The boreholes were advanced using 4-inch nominal diameter continuous flight augers. Samples of the subsurface materials encountered were obtained using split-barrel and California barrel sampling techniques in general accordance with ASTM Specifications D1586 and D3550, respectively. In the split-barrel and California barrel sampling techniques, standard sampling spoons are driven into the ground by means of a 140-pound hammer falling a distance of 30 inches. The number of blows required to advance the samplers is recorded and is used to estimate the in- situ relative density of cohesionless materials and, to a lesser degree of accuracy, the consistency of cohesive soils and hardness of weathered bedrock. In the California barrel sampling procedure, samples of the subsurface soils 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 performed on each of the recovered samples. In addition, the unconfined strength of appropriate samples was estimated using a calibrated hand penetrometer. Washed sieve analysis and Atterberg limits tests were completed on selected samples to evaluate the quantity and plasticity of the fines in the subgrade soils. Swell/consolidation tests were completed on selected samples to evaluate the potential for subgrade materials to change volume with variation in moisture content and load. Results of the outlined tests are indicated on the attached boring logs and summary sheets. As a part of the testing program, all samples were examined in the laboratory and classified in accordance with the attached General Notes and the Unified Soil Classification System based on the texture and plasticity of the soil. The estimated group symbol for the Unified Soil Classification System is indicated on the boring logs. A brief description of the Unified Soil Classification System is included with this report. Classification of the bedrock was based on visual and tactual evaluation of auger cuttings and disturbed samples. Coring and/or petrographic analysis may reveal other rock types. Earth Engineering Consultants, LLC EEC Project No. 1142088A January 6, 2015 Page 3 SITE AND SUBSURFACE CONDITIONS Lot 18 of the Midpoint Development Property is located northeast of Midpoint Drive and west of Sharp Point Drive. The building lot was vegetated and relatively flat at the time of our exploration. Evidence of prior building construction was not observed on the referenced lot by EEC personnel. An EEC field engineer was on site during drilling to evaluate the subsurface conditions encountered and direct the drilling activities. Field logs prepared by EEC site personnel were based on visual and tactual observation of disturbed samples and auger cuttings. The final boring logs included with this report may contain modifications to the field logs based on the results of laboratory testing and evaluation. Based on the results of the field borings and laboratory evaluation, subsurface conditions can be generalized as follows. Top soil and vegetation was encountered at the surface of the boring locations. The top soil and vegetation was underlain by sandy lean clay / clayey sand which extended to depths of approximately 7 to 8 feet. The near surface soils were relatively dry and stiff to very stiff at the time of drilling and exhibited moderate swell potential at current moisture and density conditions. The sandy lean clay / clayey sand was underlain by sands and gravels. The sands and gravels were medium dense to dense in consistency. The granular soils extended to the bottom of the borings at depths of approximately 10 to 25 feet below present site grades, at boring B-1 and B-3 locations and to the bedrock formation in the vicinity of boring B-2. Claystone/siltstone bedrock was encountered at an approximate depth of 23 feet below site grades at B-2 and extended to the depths explored. The stratification boundaries indicated on the boring logs represent the approximate locations of changes in soil and bedrock types. In-situ, the transition of materials may be gradual and indistinct. Earth Engineering Consultants, LLC EEC Project No. 1142088A January 6, 2015 Page 4 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, groundwater was observed at approximately 9 to 10 feet below ground surface in the borings. 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. 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 over time. 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. Perched water is commonly encountered in soils overlying less permeable bedrock. The location and amount of perched water can also vary over time depending on hydrologic conditions and other conditions not apparent at the time of this report. ANALYSIS AND RECOMMENDATIONS Swell – Consolidation Test Results The swell-consolidation test is performed to evaluate the swell or collapse potential of soils to help determine foundation, floor slab and pavement design criteria. In this test, samples obtained directly from the California sampler are placed in a laboratory apparatus and inundated with water under a predetermined load. The swell-index is the resulting amount of swell or collapse under the initial load expressed as a percent of the sample’s initial thickness. After the initial swell/consolidation period, additional incremental loads are applied to evaluate the swell pressure and/or consolidation response. Earth Engineering Consultants, LLC EEC Project No. 1142088A January 6, 2015 Page 5 For this analysis, we conducted three (3) swell-consolidation tests. The (+) test result indicates the material’s swell potential while the (-) test result indicates the materials collapse potential when inundated with water. The following table summarizes the swell- consolidation laboratory test results. Boring No. Depth, ft. Material Type Swell Consolidation Test Results In-Situ Moisture Content, % Dry Density, PCF Inundation Pressure, psf Swell Index, % (+/-) 1 2 Sandy Lean Clay 9.6 120.2 150 (+) 5.6 2 4 Clayey Sand 6.3 114.3 500 (+) 2.1 3 2 Sandy Lean Clay / Clayey Sand 5.6 112.9 150 (+) 4.4 Colorado Association of Geotechnical Engineers (CAGE) uses the following information to provide uniformity in terminology between geotechnical engineers to provide a relative correlation of slab performance risk to measured swell. “The representative percent swell values are not necessarily measured values; rather, they are a judgment of the swell of the soil and/or bedrock profile likely to influence slab performance.” Geotechnical engineers use this information to also evaluate the swell potential risks for foundation performance based on the risk categories. Recommended Representative Swell Potential Descriptions and Corresponding Slab Performance Risk Categories Slab Performance Risk Category Representative Percent Swell (500 psf Surcharge) Representative Percent Swell (1000 psf Surcharge) Low 0 to < 3 0 < 2 Moderate 3 to < 5 2 to < 4 High 5 to < 8 4 to < 6 Very High > 8 > 6 Based on the laboratory test results, the in-situ samples analyzed for this project were generally within the moderate range near surface and low range with increased depth. The higher swell- index values were of dry and dense subgrade samples obtained at depths of 2 feet. Earth Engineering Consultants, LLC EEC Project No. 1142088A January 6, 2015 Page 6 General The in-place near surface sandy lean clay / clayey sand is moderately plastic and, at the time of drilling, was relatively dry. At current moisture-density, the soil has potential for expanding subsequent to construction with increase in moisture content. Underlying soils generally exhibited higher moisture contents and; therefore, lower potential to swell. Post construction expansion of the near surface subgrades would cause heaving of floor slabs and/or pavements supported directly on or above the near surface soils. To reduce the potential movement of foundations, floor slabs, flatwork and pavements included herein are recommendations for an overexcavation and replacement concept. This approach will significantly reduce but not eliminate post-construction movement. Site Preparation All existing topsoil/vegetation should be removed from the site improvement areas. To reduce the potential for post-construction movement caused by expansion of the dry, in-situ soils, we recommend the entire building footprint be overexcavated and replaced as moisture conditioned, compaction controlled fill. The overexcavation should extent to a depth of a least 3 feet below existing site grades. Since movement of pavements is generally more tolerable, in our opinion, the overexcavation depth in the pavement areas could be reduced to 2 feet below existing site grades. The overexcavated areas should extend laterally in all directions beyond the edges of the foundations/pavements a minimum 8 inches for every 12 inches of overexcavated depth. After removal of all topsoil/vegetation within the planned development areas, as well as removal of unacceptable or unsuitable subsoils and removal of overexcavation materials, and prior to placement of fill and/or site improvements, the exposed soils should 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. Earth Engineering Consultants, LLC EEC Project No. 1142088A January 6, 2015 Page 7 Fill materials used to replace the overexcavated zone and establish grades in the building areas and pavement/flatwork areas, after the initial zone has been prepared as recommended above, should consist of approved on-site lean clay subsoils or approved structural fill material which is free from organic matter and debris. If on-site lean clay subsoils are used as engineered fill, they should be placed in maximum 9-inch loose lifts, and be moisture conditioned and compacted as recommended for the scarified soils. If structural fill materials are used they should be graded similarly to a CDOT Class 5, 6 or 7 aggregate base with sufficient fines to prevent ponding of water within the fill. Structural fill material should be placed in loose lifts not to exceed 9 inches thick, adjusted to a workable moisture content and compacted to at least 95% of standard Proctor maximum dry density as determined by ASTM Specification D698. Care should be exercised after preparation of the subgrades to avoid disturbing the subgrade materials. Positive drainage should be developed away from the structures and pavements to avoid wetting of subgrade materials. Subgrade materials becoming wet subsequent to construction of the site improvements can result in unacceptable performance. Footing Foundations Footing foundations bearing on a zone of moisture conditioned and recompacted materials, prepared as previously outlined, could be designed for a maximum net allowable total load bearing pressure of 1,500 psf. Total loads include full dead and live loads. We estimate the long-term settlement of footing foundations, designed and constructed as outlined above, would be less than 1 inch. After placement of the fill materials, care should be taken to avoid excessive wetting or drying of those materials. Bearing materials which are loosened or disturbed by the construction activities or materials which become dry and desiccated or wet and softened should be removed and replaced or reworked in place prior to construction of the overlying improvements. Earth Engineering Consultants, LLC EEC Project No. 1142088A January 6, 2015 Page 8 Exterior foundations and foundations in unheated areas should be located at least 30 inches below adjacent exterior grade to provide frost protection. We recommend formed continuous footings have a minimum width of 12 inches and isolated column foundations have a minimum width of 24 inches. Floor Slabs In our opinion, floor slabs could be supported on a zone of engineered fill material following the protocol outlined in the section titled “Site Preparation”. Floor slabs supported on reconditioned engineered fill could be designed using a modulus of subgrade support (k- value) of 100 pci. Care should be taken after preparation of the subgrades to avoid disturbing the subgrade materials. Materials which are loosened or materials which become dry and desiccated or wet and softened should be removed and replaced prior to placement of the overlying floor slabs. Care should be taken to maintain proper moisture contents in the subgrade soils prior to placement of any overlying improvements. An underslab gravel layer or thin leveling course could be used underneath the concrete floor slabs to provide a capillary break mechanism, a load distribution layer, and as a leveling course for the concrete placement. 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. Earth Engineering Consultants, LLC EEC Project No. 1142088A January 6, 2015 Page 9 Seismic Conditions The site soil conditions consist of approximately 23 feet of overburden soils overlying moderately hard bedrock. For those site conditions, the 2012 International Building Code indicates a Seismic Site Classification of D. Lateral Earth Pressures Site improvements constructed below grade would be subject to lateral earth pressures and should be evaluated during design. 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. 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 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 on-site cohesive subsoils or approved imported granular materials. 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. 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, 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. 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. Earth Engineering Consultants, LLC EEC Project No. 1142088A January 6, 2015 Page 10 Soil Type On-Site Lean Clay Imported Granular Structural Fill Wet Unit Weight (pcf) 125 135 Saturated Unit Weight (pcf) 130 145 Friction Angle (ϕ) – (assumed) 20° 30° Active Pressure Coefficient 0.49 0.33 At-rest Pressure Coefficient 0.66 0.50 Passive Pressure Coefficient 2.04 3.00 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. 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. Pavements Subgrades for site pavements should be prepared as outlined in the section titled "Site Preparation." It will be imperative to maintain the moisture content of the prepared subgrade up to and immediately prior to surfacing. Subgrade soils allowed to become dry and dense would be prone to swelling, potentially causing additional post-construction heaving of the site pavements. Densification of subgrade soils can occur with construction traffic. Prior to surfacing the roadway subgrades with aggregate base, we recommend the subgrades be proof rolled to help identify any soft or yielding areas. Soft or yielding areas delineated by the proof rolling operations should be undercut or stabilized in-place to achieve the appropriate subgrade support. If unstable subgrades exist due to pumping conditions after subgrade preparation stage, consideration should be given to stabilizing top 12 inches of pavement subgrades with the use of an ASTM C618 Class C fly ash. We estimate stabilization of the site clayey sand Earth Engineering Consultants, LLC EEC Project No. 1142088A January 6, 2015 Page 11 soils could be accomplished by incorporating at least 13%, by dry weight of Class C fly ash into the upper 12 inches of subgrade. To take full advantage of the increased stiffness of a stabilized subgrade for a reduction in pavement thickness, a mix design utilizing the fly ash with the site soils would be required prior to surfacing. We expect the site pavements will include areas designated primarily for automobile traffic use and areas for heavy-duty truck traffic. For design purposes, an assumed equivalent daily load axle (EDLA) rating of 5 is used in the automobile areas and an EDLA rating of 50 in the heavy-duty areas. A Hveem stabilometer R-value of 5 was assumed and used in design. Hot mix asphalt (HMA) underlain by aggregate base course with a fly ash treated subgrade, or a non-reinforced concrete pavement may be feasible options for the proposed on-site paved sections. HMA pavements may show rutting and distress in areas of heavy truck traffic (trash truck routes) or in truck loading and turning areas. Concrete pavements should be considered in those areas. Suggested pavement sections are provided in the table below. The outlined pavement sections are minimums and thus, periodic maintenance should be expected. RECOMMENDED MINIMUM PAVEMENT SECTIONS Automobile Parking Heavy Duty Areas 18-kip EDLA 18-kip ESAL Reliability Resilient Modulus PSI Loss 5 36,500 75% 3025 2.5 50 365,000 75% 3025 2.2 Design Structure Number 2.48 3.56 Composite Section – Option A (assume Stable Subgrade) Hot Mix Asphalt Aggregate Base Course Structure Number 4" 7" (2.53) 5-1/2" 11" (3.63) Composite Section with Fly Ash Treated Subgrade Hot Mix Asphalt Aggregate Base Course Fly Ash Treated Subgrade (assume half-credit) Structure Number 3" 6" 12" (2.58) 5" 7" 12" (3.57) Earth Engineering Consultants, LLC EEC Project No. 1142088A January 6, 2015 Page 12 We recommend aggregate base be graded to meet a Class 5 or Class 6 aggregate base. Aggregate base should be adjusted in moisture content and compacted to achieve a minimum of 95% of standard Proctor maximum dry density. HMA should be graded to meet a SX (75) or S (75) with PG 58-28 binder. The HMA should be designed in accordance with LCUASS design criteria. HMA should be compacted to achieve 92 to 96% of the mix's theoretical maximum specific gravity (Rice Value). Portland cement concrete should be an acceptable exterior pavement mix with a minimum 28- day compressive strength of 4,000 psi and should be air entrained. The recommended pavement sections are minimums, thus, periodic maintenance should be expected. Longitudinal and transverse joints should be provided as needed in concrete pavements for expansion/contraction and isolation. The location and extent of joints should be based upon the final pavement geometry. Sawed joints should be cut in accordance with ACI recommendations. All joints should be sealed to prevent entry of foreign material and dowelled where necessary for load transfer. Since the cohesive soils on the site have some shrink/swell potential, pavements could crack in the future primarily because of the volume change of the soils when subjected to changes in moisture content of the subgrades. The cracking, while not desirable, does not necessarily constitute structural failure of the pavement. Stabilization of the subgrades will reduce the potential for cracking of the pavements. The collection and diversion of surface drainage away from paved areas is critical to the satisfactory performance of the pavement. Drainage design should provide for the removal of water from paved areas in order to reduce the potential for wetting of the subgrade soils. Long-term pavement performance will be dependent upon several factors, including maintaining subgrade moisture levels and providing for preventive maintenance. The following recommendations should be considered the minimum: Earth Engineering Consultants, LLC EEC Project No. 1142088A January 6, 2015 Page 13  The subgrade and the pavement surface should be adequately sloped to promote proper surface drainage.  Install pavement drainage surrounding areas anticipated for frequent wetting (e.g. garden centers, wash racks)  Install joint sealant and seal cracks immediately.  Seal all landscaped areas in, or adjacent to pavements to minimize or prevent moisture migration to subgrade soils.  Place and compact low permeability backfill against the exterior side of curb and gutter. Preventive maintenance should be planned and provided for through an on-going pavement management program. Preventive maintenance activities are intended to slow the rate of pavement deterioration, and to preserve the pavement investment. Preventive maintenance consists of both localized maintenance (e.g. crack and joint sealing and patching) and global maintenance (e.g. surface sealing). Preventive maintenance is usually the first priority when implementing a planned pavement maintenance program and provides the highest return on investment for pavements. Prior to implementing any maintenance, additional engineering observation is recommended to determine the type and extent of preventive maintenance. Site grading is generally accomplished early in the construction phase. However as construction proceeds, the subgrade may be disturbed due to utility excavations, construction traffic, desiccation, or rainfall. As a result, the pavement subgrade may not be suitable for pavement construction and corrective action will be required. The subgrade should be carefully evaluated at the time of pavement construction for signs of disturbance, rutting, or excessive drying. If disturbance has occurred, pavement subgrade areas should be reworked, moisture conditioned, and properly compacted to the recommendations in this report immediately prior to paving. If during or after placement of the stabilization or initial lift of pavement, the area is observed to be yielding under vehicle traffic or construction equipment, it is recommended that EEC be contacted for additional alternative methods of stabilization, or a change in the pavement section. Earth Engineering Consultants, LLC EEC Project No. 1142088A January 6, 2015 Page 14 Water Soluble Sulfates The results of water soluble sulfate testing on a selected sample of the near surface soils indicated a sulfate (SO4) content of 700 mg/kg. ACI 318, Section 4.2 indicates the site soils have a low risk of sulfate attack on concrete. Therefore, ACI 318, Section 4.2 suggests Type I Portland cement may be suitable for concrete development. However, if there is no, or minimal cost differential, a Type I/II Portland cement is recommended for additional sulfate resistance of construction concrete. Utilities Near surface, the lean clay soils were relatively dry and stiff, generally becoming more moist and medium stiff with depth into medium dense to dense sand and gravel approaching groundwater. Cuts extending into the near surface relatively dry lean clay soils would be expected to stand on relatively steep temporary slopes. However, cuts extending to greater depths could expose soft, wet, pumping soils and groundwater. The soft, wet cohesive soils and underlying granular materials may be unstable in the trench excavations. Stabilization of the sides and bottoms of some of the trenches and at least some dewatering should be anticipated for deeper utilities. Although the excavated soils could be used for backfilling the utility excavations, drying of those soils will be necessary before the excavated material can be used for backfilling. 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. Earth Engineering Consultants, LLC EEC Project No. 1142088A January 6, 2015 Page 15 Other Considerations Positive drainage should be developed away from the structure and pavement areas with a minimum slope of 1 inch per foot for the first 10 feet away from the improvements in landscape areas. 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. Lawn watering systems should not be placed within 5 feet of the perimeter of the building and parking areas. Spray heads should be designed not to spray water on or immediately adjacent to the structure or site pavements. Roof drains should be designed to discharge at least 5 feet away from the structure and away from the pavement areas. 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 engineer be retained for testing and observations during earthwork and foundation construction phases to help determine that the design requirements are fulfilled. Earth Engineering Consultants, LLC EEC Project No. 1142088A January 6, 2015 Page 16 This report has been prepared for the exclusive use of Thunderpup Construction, Inc. 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 THUNDERPUP CONSTRUCTION FORT COLLINS, COLORADO EEC PROJECT NO. 1142088 DECEMBER 2014 DATE: RIG TYPE: CME55 FOREMAN: DG AUGER TYPE: 4" CFA SPT HAMMER: AUTOMATIC SOIL DESCRIPTION D N QU MC DD -200 TYPE (FEET) (BLOWS/FT) (PSF) (%) (PCF) LL PI (%) PRESSURE % @ 500 PSF TOPSOIL & VEGETATION _ _ 1 SANDY LEAN CLAY (CL) _ _ brown 2 very stiff _ _ % @ 150 PSF CS 3 16 9000+ 9.6 119.6 30 18 58.9 4,800 psf 5.6% _ _ 4 _ _ brown / tan SS 5 6 6000 11.3 medium stiff _ _ 6 _ _ 7 _ _ 8 _ _ SAND & GRAVEL (SP/GP) 9 brown / grey / red _ _ dense CS 10 30 4000 8.7 131.0 with clayey seams & cobbles _ _ 11 _ _ 12 _ _ 13 _ _ 14 _ _ medium dense SS 15 33 -- with cobbles; wet cave in, drive on bottom _ _ BOTTOM OF BORING DEPTH 15.5' 16 _ _ 17 _ _ 18 _ _ 19 _ _ 20 _ _ 21 _ _ 22 _ _ 23 _ _ 24 _ _ 25 _ _ Earth Engineering Consultants, LLC A-LIMITS SWELL DATE: RIG TYPE: CME55 FOREMAN: DG AUGER TYPE: 4" CFA SPT HAMMER: AUTOMATIC SOIL DESCRIPTION D N QU MC DD -200 TYPE (FEET) (BLOWS/FT) (PSF) (%) (PCF) LL PI (%) PRESSURE % @ 500 PSF TOPSOIL & VEGETATION _ _ 1 CLAYEY SAND (SC) _ _ mottled / brown / red 2 medium dense _ _ mottled 3 _ _ 4 _ _ CS 5 19 9000+ 6.3 119.3 27 14 45.1 2000 psf 2.1% _ _ 6 _ _ 7 _ _ SAND & GRAVEL (SP/GP) 8 brown / grey / red _ _ dense 9 _ _ SS 10 48 -- 4.3 with cobbles _ _ 11 _ _ 12 _ _ 13 _ _ 14 _ _ cave in, auger cuttings SS 15 -- -- _ _ 16 _ _ 17 _ _ 18 _ _ 19 _ _ cave in, auger cuttings SS 20 -- -- _ _ 21 _ _ 22 _ _ 23 _ _ CLAYSTONE 24 grey _ _ wet cave in, auger cuttings SS 25 -- -- BOTTOM OF BORING DEPTH 25.5' _ _ Earth Engineering Consultants, LLC A-LIMITS SWELL DATE: RIG TYPE: CME55 FOREMAN: DG AUGER TYPE: 4" CFA SPT HAMMER: AUTOMATIC SOIL DESCRIPTION D N QU MC DD -200 TYPE (FEET) (BLOWS/FT) (PSF) (%) (PCF) LL PI (%) PRESSURE % @ 500 PSF TOPSOIL & VEGETATION _ _ 1 SANDY LEAN CLAY / CLAYEY SAND (CL/SC) _ _ brown / red 2 very stiff _ _ % @ 150 PSF CS 3 17 9000+ 5.6 117.1 1,600 psf 4.4% _ _ 4 _ _ stiff SS 5 9 5000 10.7 _ _ 6 _ _ 7 _ _ SAND & GRAVEL (SP/GP) 8 brown / grey / red _ _ medium dense 9 with cobbles _ _ SS 10 28 -- 7.5 _ _ BOTTOM OF BORING DEPTH 10.5' 11 _ _ 12 _ _ 13 _ _ 14 _ _ 15 _ _ 16 _ _ 17 _ _ 18 _ _ 19 _ _ 20 _ _ 21 _ _ 22 _ _ 23 _ _ 24 _ _ 25 _ _ Earth Engineering Consultants, LLC A-LIMITS SWELL Project: Location: Project #: Date: SWELL / CONSOLIDATION TEST RESULTS Material Description: Brown SANDY LEAN CLAY (CL) Sample Location: Boring 1, Sample 1, Depth 2' Liquid Limit: 30 Plasticity Index: 18 % Passing #200: 58.9% Beginning Moisture: 9.6% Dry Density: 120.2 pcf Ending Moisture: 14.1% Swell Pressure: 4800 psf % Swell @ 150: 5.6% Thunderpup Construction Fort Collins, Colorado 1142088A December 2014 -10.0 -8.0 -6.0 -4.0 -2.0 0.0 2.0 4.0 6.0 8.0 10.0 0.01 0.1 1 10 Percent Movement Load (TSF) Consolidatio Swell Water Added Project: Location: Project #: Date: Thunderpup Construction Fort Collins, Colorado 1142088A December 2014 Beginning Moisture: 6.3% Dry Density: 114.3 pcf Ending Moisture: 16.6% Swell Pressure: 2000 psf % Swell @ 500: 2.1% Sample Location: Boring 2, Sample 1, Depth 4' Liquid Limit: 27 Plasticity Index: 14 % Passing #200: 45.1% SWELL / CONSOLIDATION TEST RESULTS Material Description: Mottled, brown, red CLAYEY SAND (SC) -10.0 -8.0 -6.0 -4.0 -2.0 0.0 2.0 4.0 6.0 8.0 10.0 0.01 0.1 1 10 Percent Movement Load (TSF) Consolidatio Swell Water Added Project: Location: Project #: Date: SWELL / CONSOLIDATION TEST RESULTS Material Description: Brown SANDY LEAN CLAY / CLAYEY SAND (CL / SC) Sample Location: Boring 3, Sample 1, Depth 2' Liquid Limit: - - Plasticity Index: - - % Passing #200: - - Beginning Moisture: 5.6% Dry Density: 112.9 pcf Ending Moisture: 19.8% Swell Pressure: 1600 psf % Swell @ 150: 4.4% Thunderpup Construction Fort Collins, Colorado 1142088A December 2014 -10.0 -8.0 -6.0 -4.0 -2.0 0.0 2.0 4.0 6.0 8.0 10.0 0.01 0.1 1 10 Percent Movement Load (TSF) Consolidatio Swell Water Added 6" (152.4 mm) 5" (127 mm) 4" (101.6 mm) 3" (76 mm) 2 1/2" (63 mm) 2" (50 mm) 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: Thunderpup Construction Location: Fort Collins, Colorado Project No: 1142088A Sample ID: Boring 2, Sample 2, 9' Sample Desc.: Brown Sand and Gravel Date: December 2014 37 31 26 18 11.9 80 71 63 60 49 100 100 92 86 82 100 100 100 100 100 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: Thunderpup Construction Fort Collins, Colorado 1142088A Boring 2, Sample 2, 9' Brown Sand and Gravel December 2014 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 Water Soluble Sulfate Ion ‐ Measurement Project No: 1142088A Project Name: Thunderpup Construction No. of Samples: 1 Test Standards: CP‐L2103 / ASTM‐C1580 Measurement Date: 12/29/2014 Sample ID (mg/l or ppm) (% of Soil by Wt) 1B‐1 S‐2 4' 700 0.07 Soluble Sulfate Content (SO4) SURFACE ELEV N/A 24 HOUR N/A FINISH DATE 12/10/2014 AFTER DRILLING N/A SHEET 1 OF 1 WATER DEPTH START DATE 12/10/2014 WHILE DRILLING 10' THUNDERPUP CONSTRUCTION FORT COLLINS, COLORADO PROJECT NO: 1142088A LOG OF BORING B-3 DECEMBER 2014 SURFACE ELEV N/A 24 HOUR N/A FINISH DATE 12/10/2014 AFTER DRILLING N/A SHEET 1 OF 1 WATER DEPTH START DATE 12/10/2014 WHILE DRILLING 10' THUNDERPUP CONSTRUCTION FORT COLLINS, COLORADO PROJECT NO: 1142088A LOG OF BORING B-2 DECEMBER 2014 SURFACE ELEV N/A 24 HOUR N/A FINISH DATE 12/10/2014 AFTER DRILLING N/A SHEET 1 OF 1 WATER DEPTH START DATE 12/10/2014 WHILE DRILLING 9.5' THUNDERPUP CONSTRUCTION FORT COLLINS, COLORADO PROJECT NO: 1142088A LOG OF BORING B-1 DECEMBER 2014 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 PCC (Non-reinforced) – placed on a stable subgrade 5" 7"