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Home My WebLink AboutQUIK TRIP - PDP230010 - SUBMITTAL DOCUMENTS - ROUND 1 - GEOTECHNICAL (SOILS) REPORT (2)SUBSURFACE EXPLORATION / PAVEMENT DESIGN REPORT PROPOSED BRIDGE – GATEWAY AT PROSPECT DEVELOPMENT NORTHWEST OF PROSPECT ROAD AND I-25 FRONTAGE ROAD FORT COLLINS, COLORADO EEC PROJECT NO. 1212028 Prepared for: Gateway Properties Company, LLC c/o TB ǀ Group 444 Mountain Avenue Berthoud, Colorado 80513 Attn: Mr. Jim Birdsall (Jim@TBGroup.us) Prepared by: Earth Engineering Consultants, LLC 4396 Greenfield Drive Windsor, Colorado 80550 4396 GREENFIELD DRIVE W INDSOR, COLORADO 80550 (970) 545-3908 FAX (970) 663-0282 www.earth-engineering.com May 14, 2021 Gateway Properties Company, LLC c/o TB ǀ Group 444 Mountain Avenue Berthoud, Colorado 80513 Attn: Mr. Jim Birdsall (Jim@TBGroup.us) Re: Subsurface Exploration /Pavement Design Report Proposed Bridge – Gateway at Prospect Development Northeast of Prospect Road and I-25 Frontage Road Fort Collins, Colorado EEC Project No. 1212028 Mr. Birdsall: Enclosed, herewith, are the results of the geotechnical subsurface exploration completed by Earth Engineering Consultants, LLC personnel for the proposed bridge project planned for construction within the Gateway at Prospect Development project in Fort Collins, Colorado. As we understand, this project involves the design and construction of a new bridge structure as shown on the enclosed site plan. This study was completed in general accordance with our Proposal dated March 16, 2021. For this project, two (2) borings were drilled at selected locations on either bank of the channel alignment within the extent of the proposed bridge improvements. The test borings were drilled to depths of approximately 35 feet below existing site grades within the proposed bridge area. The approximate boring location is indicated on the attached test boring location diagram. Sparse vegetation and topsoil was encountered at the surface of the borings and was underlain by a zone of sandy lean clay soils. The sandy lean clay overburden soils were medium stiff to soft due to shallow groundwater and extended to granular sand soils at depths of approximately 9 to 15 feet below the ground surface. The sandy lean clay soils exhibited low to nil swell potential and compressible conditions nearing the groundwater table at current moisture and density conditions. Underlying the sandy lean clay was well graded sand with varying amounts of silt and gravel. The sand was loose to dense and extended to the underlying bedrock foundation at SUBSURFACE EXPLORATION / PAVEMENT DESIGN REPORT PROPOSED BRIDGE – GATEWAY AT PROSPECT DEVELOPMENT NORTHWEST OF PROSPECT ROAD AND I-25 FRONTAGE ROAD FORT COLLINS, COLORADO EEC PROJECT NO. 1212028 May 14, 2021 INTRODUCTION The subsurface exploration for the proposed bridge for the Gateway at Prospect Development located northwest of Prospect Road and I-25 Frontage Road in Fort Collins, Colorado has been completed. The bridge project involves the construction of a new bridge over Boxelder Creek. Design parameters for a new foundation system have been provided in this report. The project site and the proposed improvements are shown on the attached test boring location diagram included with this report. Results of the subsurface exploration are provided with this report. For this project, two (2) borings were drilled at selected locations on either bank of the creek within the extent of the proposed bridge project. The test borings were drilled to depths of approximately 35 feet below existing site grades within the proposed bridge area. Individual boring logs and a boring location diagram are provided with this report. The purpose of this report is to describe the subsurface conditions encountered in the test borings, provide lab testing results, and submit recommendations for foundation systems, subgrade support and pavement sections for the proposed roadway improvements. EXPLORATION AND TESTING PROCEDURES The boring locations were established in the field by EEC personnel by pacing and estimating bearings from identifiable site features. The foundation related borings were completed on either bank in the proposed bridge structure construction area as shown on the attached Boring Location Diagram. The location of the boring should be considered accurate only to the degree implied by the methods used to make the field measurements. The test borings were performed with a CME-55 drill rig equipped with a hydraulic head employed in drilling and sampling operations. The boreholes were advanced by using 4-inch nominal diameter continuous flight augers. Samples of the subsurface materials encountered Earth Engineering Consultants, LLC EEC Project No. 1212028 Proposed Bridge – Gateway at Prospect Road Development May 14, 2021 Page 2 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 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 soils and, to a lesser degree of accuracy, the consistency of cohesive materials. All samples obtained in the field were sealed and returned to the 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 percentage and plasticity of fines in the subgrades. Swell/consolidation tests were performed on representative samples to evaluate the soil’s tendency to change volume with variation in moisture content. Soluble sulfate tests were completed on selected samples to estimate the potential for sulfate attack on site cast concrete. 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 by an engineer and classified in 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. SUBSURFACE CONDITIONS Based on the results of field boring and laboratory testing, subsurface conditions can be generalized as follows. The proposed bridge construction area is currently undeveloped. Vegetation and topsoil was encountered on the banks of the creek. Earth Engineering Consultants, LLC EEC Project No. 1212028 Proposed Bridge – Gateway at Prospect Road Development May 14, 2021 Page 3 The surficial vegetation and topsoil was generally underlain by a zone of sandy lean clay soils. The sandy lean clay overburden soils were medium stiff to soft due to shallow groundwater and extended to granular sand soils at depths of approximately 9 to 15 feet below the ground surface. The sandy lean clay soils exhibited low to nil swell potential and compressible conditions nearing the groundwater table at current moisture and density conditions. Underlying the sandy lean clay was well graded sand with varying amounts of silt and gravel. The sand was loose to dense and extended to the underlying bedrock foundation at depths of approximately 17 to 21 feet below the ground surface. Claystone bedrock was encountered below the sand soils and extended to the depths explored. The bedrock was generally weathered to hard and exhibited low swell potential. The stratification boundaries indicated on the boring logs represent the approximate locations of changes in soil; in-situ, the transition of materials may be gradual and indistinct. In addition, the soil borings show conditions at the test borings locations; variations in subsurface conditions can occur at relatively short distances from the boring locations. GROUNDWATER CONDITIONS At the time of drilling, groundwater was encountered at depths of approximately 6 to 7 feet below the ground surface. The borings were backfilled upon completion; therefore, stabilized groundwater measurements were not obtained. 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. Monitoring in cased borings, sealed from the influence of surface infiltration, would be required to more accurately evaluate groundwater levels and fluctuations in the groundwater levels over time. Zones of perched and/or trapped groundwater may occur at times in the subsurface soils. The observations provided in this report represent groundwater conditions at the time of the field exploration, and may not be indicative of other times, or at other locations. Earth Engineering Consultants, LLC EEC Project No. 1212028 Proposed Bridge – Gateway at Prospect Road Development May 14, 2021 Page 4 ANALYSIS AND RECOMMENDATIONS Swell – Consolidation Test Results The swell-consolidation test is performed to evaluate the swell or collapse potential of soils or bedrock to assist in determining foundation, floor slab, and pavement design recommendations. In this test, relatively undisturbed samples obtained directly from the California barrel sampler are placed in a laboratory apparatus and inundated with water under a predetermined load, generally at 150 psf for pavement analyses. All samples are inundated with water and monitored for swell and consolidation. The swell-index is the resulting amount of swell or collapse after inundation, expressed as a percent of the sample’s initial thickness. After the inundation period, additional incremental loads are applied to evaluate the swell pressure and/or consolidation. For this assessment, we conducted four (4) swell-consolidation tests at various elevations. The swell index values revealed low to moderate swell potential characteristics of the underlying subgrade soils. A summary of the laboratory swell-consolidation test results is presented in Table I below and graphical results are also included with this report. Table I – Laboratory Swell-Consolidation Test Results No. of Samples Tested Pre-Load / Inundation Pressure, PSF Description of Material In-Situ Characteristics Range of Swell – Index Test Results Range of Moisture Contents, % Range of Dry Densities, PCF Low End, % High End, % Low End, PCF High End, PCF Low End (+/-) % High End, (+/-) % 2 500 Sandy Lean Clay 26.3 47.7 78.2 98.2 (-) 1.2 (-) 0.4 2 2000 Claystone 14.0 14.3 113.9 118.9 (+) 0.3 (+) 1.5 The Colorado Association of Geotechnical Engineers (CAGE) uses the following information to provide uniformity in terminology between geotechnical engineers to provide a relative correlation risk performance 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. Earth Engineering Consultants, LLC EEC Project No. 1212028 Proposed Bridge – Gateway at Prospect Road Development May 14, 2021 Page 5 TABLE II: 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 The overburden sandy lean clay soils exhibited low swell potential but were slightly compressible due to the shallow groundwater. The claystone bedrock exhibited low swell potential at current moisture-density conditions under higher inundation loads. General Considerations and Site Preparation All existing topsoil/vegetation should be removed from the site improvement areas. After removal of topsoil/vegetation within the planned development areas, as well as removal of unacceptable or unsuitable subsoils, and prior to placement of fill and/or site improvements, the exposed soils should be scarified to a 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. Areas of soft/compressible cohesive subsoils across the site may require ground stabilization procedures to create a working platform for construction equipment prior to placement of any additional fill. If necessary, consideration could be given to placement of a granular material, such as a 3-inch minus pit run and/or recycled concrete or equivalent material, embedded into the soft soils, prior to placement of additional fill material or operating heavy earth-moving equipment. Supplemental recommendations can be provided upon request. Fill materials used to establish grades for the bridge, bridge abutments and any associated flatwork areas, after the initial zone has been prepared as recommended above, should consist of approved on-site sandy lean clay subsoils or approved structural fill material which is free from organic matter and debris. If on-site cohesive 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 Earth Engineering Consultants, LLC EEC Project No. 1212028 Proposed Bridge – Gateway at Prospect Road Development May 14, 2021 Page 6 similarly to a CDOT Class 5, 6 or 7 aggregate base course (ABC) 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. Drilled Piers/Caissons Foundations Due to the expected bridge loading conditions and soft/compressible cohesive overburden nearing the shallow groundwater table, consideration should be given to supporting the proposed bridge on a grade beam and straight shaft drilled pier/caisson foundation system extending into the underlying bedrock formation. For axial compression loads, the drilled piers could be designed using a maximum end bearing pressure of 30,000 pounds per square foot (psf), along with a skin-friction of 3,000 psf for the portion of the pier extended into the underlying firm and/or harder bedrock formation. The piers require sufficient dead-load and/or additional penetration into the bearing strata to resist the potential uplift of the expansive materials. All piers should be designed for a minimum dead-load pressure of 5,000 psf, based upon pier end area. Straight shaft piers should be drilled a minimum of 10 feet into competent or harder bedrock with minimum pier length of at least 25 feet. Due to the weathered condition of the upper strata of bedrock, the top 3 feet should be neglected for final penetration depth. Lower values may be appropriate for pier “groupings” depending on the pier diameters and spacing. Pile groups should be evaluated individually. Required pier penetration should be balanced against potential uplift forces due to expansion of the subsoils and bedrock on the site. For design purposes, the uplift force on each pier can be determined on the basis of the following equation: Earth Engineering Consultants, LLC EEC Project No. 1212028 Proposed Bridge – Gateway at Prospect Road Development May 14, 2021 Page 7 Up = 40 x D Where: Up = the uplift force in kips, and D = the pier diameter in feet Uplift forces on piers should be resisted by a combination of dead-load and pier penetration below a depth of about 10 feet and into the bearing strata. To satisfy forces in the horizontal direction, piers may be designed for lateral loads using a coefficient of subgrade reaction for varying pier diameters is as follows: Table III – Lateral Load Coefficient of Subgrade Reaction Pier Diameter (inches) Coefficient of Subgrade Reaction (tons/ft3) Site Soils Bedrock 12 50 400 18 33 267 24 25 200 30 20 160 36 17 133 When the lateral capacity of drilled piers is evaluated by the L-Pile 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 computer program: Table IV – L-Pile Parameters Parameters On-Site Overburden Soils Bedrock Unit Weight of Soil (pcf) 120(1) 125(1) Cohesion (psf) 200 5000 Angle of Internal Friction () (degrees) 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 All piers should be reinforced full depth for the applied axial, lateral and uplift stresses imposed. The amount of reinforcing steel for expansion should be determined by the tensile force created by Earth Engineering Consultants, LLC EEC Project No. 1212028 Proposed Bridge – Gateway at Prospect Road Development May 14, 2021 Page 8 the uplift force on each pier, with allowance for dead-load. Minimum reinforcement of at least one percent of the cross-sectional area of each pier should be specified. To reduce potential uplift forces on piers, use of long grade beam spans to increase individual pier loading, and small diameter piers are recommended. For this project, use of a minimum pier diameter of 12 inches is recommended. 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 bedrock may be encountered throughout the site at various depths where specialized drilling equipment and/or rock excavating equipment may be required. Consideration should be given to obtaining a unit price for difficult caisson excavation in the contract documents for the project. To provide increased resistance to potential uplift forces, the sides of each pier should be mechanically roughened in the bearing strata below a depth of 10 feet. This should be accomplished by a roughening tooth placed on the auger. Pier bearing surfaces must be cleaned prior to concrete placement. A representative of the geotechnical engineer should inspect the bearing surface and pier configuration. We expect temporary casing may be required to maintain open boreholes. Concrete should be placed as soon as practical after drilling each shaft to reduce the potential for sloughing of sidewalls. Groundwater encountered should be removed from each pier hole prior to concrete placement. Pier concrete should be placed immediately after completion of drilling and cleaning. If casing is used for pier construction, it should be withdrawn in a slow continuous manner maintaining a sufficient head of concrete to prevent infiltration of water or the creation of voids in pier concrete. Pier concrete should have relatively high fluidity when placed in cased pier holes or through a tremie. Pier concrete with slump in the range of 6 to 8 inches is recommended. Free-fall concrete placement in piers will only be acceptable if provisions are taken to avoid striking the concrete on the sides of the hole or reinforcing steel. The use of a bottom-dump hopper/tremie pipe or an elephant's trunk discharging near the bottom of the hole where concrete segregation will be minimized, is recommended. Earth Engineering Consultants, LLC EEC Project No. 1212028 Proposed Bridge – Gateway at Prospect Road Development May 14, 2021 Page 9 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. 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. Lateral Earth Pressures Passive lateral earth pressures may help resist the driving forces for retaining wall/wing wall or other similar site structures. 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 backfill with anticipated types of soils for calculation of active, at rest and passive earth pressures are provided in the table below. Those coefficient values are based on horizontal backfill with backfill soils consisting of on-site lean clay subsoils with friction angles of 25 degrees and structural fill with friction angles of 35 degrees. Equivalent fluid pressure is equal to the appropriate coefficient times the appropriate soil unit weight. Care will be needed to account for buoyant soil weights and hydrostatic loading conditions as appropriate. 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, the top 30 inches of soil should not be used as part of the passive resistance value. Earth Engineering Consultants, LLC EEC Project No. 1212028 Proposed Bridge – Gateway at Prospect Road Development May 14, 2021 Page 10 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. Table V – Lateral Earth Pressure Coefficients Soil Type On-Site Cohesive Subsoils Imported Medium Dense Granular Wet Unit Weight (pcf) 115 135 Saturated Unit Weight (pcf) 135 140 Friction Angle () – (assumed) 25° 35° Active Pressure Coefficient 0.40 0.27 At-rest Pressure Coefficient 0.58 0.43 Passive Pressure Coefficient 2.46 3.70 The outlined values do not include factors of safety nor allowances for hydrostatic loads and are based on assumed friction angles and should be verified prior to construction. Care should be taken to develop appropriate systems in conjunction with below grade walls to eliminate potential for hydrostatic loads developing on the walls and/or design the walls to accommodate hydrostatic load conditions. Water Soluble Sulfates (SO4) The water-soluble sulfate (SO4) content of the on-site overburden subsoils, taken during our subsurface exploration at random locations and intervals are provided below. Based on reported sulfate content test results, the Class/severity of sulfate exposure for concrete in contact with the on-site subsoils is provided in this report. Table VI - Water Soluble Sulfate Test Results Sample Location Description Soluble Sulfate Content (%) B-1, S-1, at 9’ Well Graded Sand with Silt (SW-SM) 0.41 B-1, S-6, at 29’ Claystone 0.11 B-2, S-7 at 34’ Claystone 0.29 Earth Engineering Consultants, LLC EEC Project No. 1212028 Proposed Bridge – Gateway at Prospect Road Development May 14, 2021 Page 11 Based on the results as presented above, ACI 318, Section 4.2 indicates the site soils have a severe risk of sulfate attack on Portland cement concrete, therefore, ACI Class S2 requirements should be followed for concrete placed in the lean clay soils and underlying bedrock. Foundation concrete should be designed in accordance with the provisions of the ACI Design Manual, Section 318, Chapter 4. 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 that 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. This report has been prepared for the exclusive use of Gateway Properties Company, LLC c/o TB ǀ Group 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 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. 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 Group Symbol Group Name Cu≥4 and 1<Cc≤3E GW Well-graded gravel F Cu<4 and/or 1>Cc>3E 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≤3E SW Well-graded sand I Cu<6 and/or 1>Cc>3E 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 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 110PLASTICITY 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 BRIDGE AT GATEWAY AND PROSPECT ROAD FORT COLLINS, COLORADO EEC PROJECT NO. 1212028 APRIL 2021 B-2B-112Boring Location DiagramBridge - Gateway at Prospect Road and Frontage Road DevelopmentFort Collins, ColoradoEEC Project #: 1212028 Date: April 2021EARTH ENGINEERING CONSULTANTS, LLCAppro[imate BoringLocations1LegendSite PKotosPKotos taNen in appro[imatelocation, in direction oI arrow 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 _ _ 1 SANDY LEAN CLAY (CL) _ _ gray / rust 2 medium stiff _ _ 3 _ _ 4 _ _ CS 5 4 1500 26.3 95.7 34 18 55.8 < 500 psf None _ _ 6 _ _ 7 _ _ 8 _ _ 9 _ _ WELL GRADED SAND with SILT (SW-SM) SS 10 6 36.8 brown / gray / rust _ _ loose to medium dense 11 _ _ 12 _ _ 13 _ _ 14 with gravel _ _ CS 15 21 9.6 134.5 6.9 _ _ 16 _ _ 17 _ _ CLAYSTONE 18 brown / gray / rust _ _ weathered to moderately hard 19 _ _ SS 20 50/11" 9000+ 21.4 _ _ 21 _ _ 22 _ _ 23 _ _ 24 _ _ 25 Continued on Sheet 2 of 2 _ _ Earth Engineering Consultants, LLC A-LIMITS SWELL FINISH DATE 4/14/2021 SHEET 1 OF 2 WATER DEPTH START DATE 4/14/2021 WHILE DRILLING 6' BRIDGE - GATEWAY AT PROSPECT RD AND FRONTAGE RD FORT COLLINS, COLORADO LOG OF BORING B-1PROJECT NO: 1212028 APRIL 2021 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 Continued from Sheet 1 of 2 26 _ _ CLAYSTONE 27 brown / gray / rust _ _ hard 28 _ _ 29 _ _ SS 30 50/5" 9000+ 15.8 _ _ 31 _ _ 32 _ _ 33 _ _ 34 _ _% @ 2000 psf CS 35 50/4" 9000+ 14.0 111.4 3000 psf 0.3% BOTTOM OF BORING DEPTH 35' _ _ 36 _ _ 37 _ _ 38 _ _ 39 _ _ 40 _ _ 41 _ _ 42 _ _ 43 _ _ 44 _ _ 45 _ _ 46 _ _ 47 _ _ 48 _ _ 49 _ _ 50 _ _ Earth Engineering Consultants A-LIMITS SWELL N/A 4/14/2021 AFTER DRILLING 0 0 24 HOUR 0 FINISH DATE SHEET 2 OF 2 WATER DEPTH START DATE 4/14/2021 WHILE DRILLING 6' BRIDGE - GATEWAY AT PROSPECT RD AND FRONTAGE RD FORT COLLINS, COLORADO LOG OF BORING B-1 APRIL 2021PROJECT NO: 1212028 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 VEGETATION AND TOPSOIL _ _ 1 LEAN CLAY with SAND (CL) _ _ brown 2 medium stiff to soft _ _ 3 _ _ 4 _ _ SS 5 10 3500 26.7 _ _ 6 _ _ 7 _ _ 8 _ _ 9 with gypsum crystals _ _ CS 10 47.7 43 12 67.5 < 500 psf None _ _ 11 _ _ 12 _ _ 13 _ _ 14 _ _ SS 15 9 59.9 _ _ WELL GRADED SAND with SILT (SW-SM) 16 brown / gray / rust _ _ medium dense to dense 17 _ _ 18 _ _ 19 _ _ CS 20 47 10.0 119.4 10.8 _ _ 21 _ _ CLAYSTONE 22 brown / gray / rust _ _ moderately hard 23 _ _ 24 _ _ SS 25 50/7" Continued on Sheet 2 of 2 _ _ Earth Engineering Consultants, LLC A-LIMITS SWELL FINISH DATE 4/14/2021 SHEET 1 OF 2 WATER DEPTH 7'START DATE 4/14/2021 WHILE DRILLING BRIDGE - GATEWAY AT PROSPECT RD AND FRONTAGE RD FORT COLLINS, COLORADO PROJECT NO: 1212028 LOG OF BORING B-2 APRIL 2021 DATE: RIG TYPE: CME55 FOREMAN: DG WHILE DRILLING 7' AUGER TYPE: 4" CFA AFTER DRILLING 0 SPT HAMMER: AUTOMATIC 24 HOUR 0 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 _ _ CLAYSTONE 27 brown / gray / rust _ _ hard 28 _ _ 29 _ _% @ 2000 psf CS 30 50/5" 9000+ 14.3 121.5 49 29 75.2 5000 psf 1.5% _ _ 31 _ _ 32 _ _ 33 _ _ 34 _ _ SS 35 50/5" 9000+ 16.0 _ _ BOTTOM OF BORING DEPTH 35.5' 36 _ _ 37 _ _ 38 _ _ 39 _ _ 40 _ _ 41 _ _ 42 _ _ 43 _ _ 44 _ _ 45 _ _ 46 _ _ 47 _ _ 48 _ _ 49 _ _ 50 _ _ Earth Engineering Consultants A-LIMITS SWELL 4/14/2021 N/A0 FINISH DATE SHEET 2 OF 2 WATER DEPTH START DATE 4/14/2021 BRIDGE - GATEWAY AT PROSPECT RD AND FRONTAGE RD FORT COLLINS, COLORADO PROJECT NO: 1212028 LOG OF BORING B-2 APRIL 2021 Project: Location: Project #: Date: Bridge - Gateway at Prospect Rd and Frontage Rd Fort Collins, Colorado 1212028 April 2021 Beginning Moisture: 26.3% Dry Density: 98.2 pcf Ending Moisture: 29.0% Swell Pressure: < 500 psf % Swell @ 500: None Sample Location: Boring 1, Sample 1, Depth 4' Liquid Limit: 34 Plasticity Index: 18 % Passing #200: 55.8% SWELL / CONSOLIDATION TEST RESULTS Material Description: Gray / Rust Sandy Lean Clay (CL) -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 10Percent MovementLoad (TSF)SwellConsolidatioWater Added Project: Location: Project #: Date: SWELL / CONSOLIDATION TEST RESULTS Material Description: Brown / Gray / Rust Sandstone / Siltstone / Claystone Sample Location: Boring 1, Sample 7, Depth 34' Liquid Limit: - - Plasticity Index: - - % Passing #200: - - Beginning Moisture: 14.0% Dry Density: 118.9 pcf Ending Moisture: 17.3% Swell Pressure: 3000 psf % Swell @ 2000: 0.3% Bridge - Gateway at Prospect Rd and Frontage Rd Fort Collins, Colorado 1212028 April 2021 -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 10Percent MovementLoad (TSF)SwellConsolidatioWater Added Project: Location: Project #: Date: Bridge - Gateway at Prospect Rd and Frontage Rd Fort Collins, Colorado 1212028 April 2021 Beginning Moisture: 47.7% Dry Density: 78.2 pcf Ending Moisture: 39.2% Swell Pressure: < 500 psf % Swell @ 500: None Sample Location: Boring 2, Sample 2, Depth 9' Liquid Limit: 43 Plasticity Index: 12 % Passing #200: 67.5% SWELL / CONSOLIDATION TEST RESULTS Material Description: Brown Lean Clay with Sand (CL) -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 10Percent MovementLoad (TSF)SwellConsolidatioWater Added Project: Location: Project #: Date: Bridge - Gateway at Prospect Rd and Frontage Rd Fort Collins, Colorado 1212028 April 2021 Beginning Moisture: 14.3% Dry Density: 113.9 pcf Ending Moisture: 19.8% Swell Pressure: 5000 psf % Swell @ 2000: 1.5% Sample Location: Boring 2, Sample 6, Depth 29' Liquid Limit: 49 Plasticity Index: 29 % Passing #200: 75.2% SWELL / CONSOLIDATION TEST RESULTS Material Description: Brown / Gray / Rust Claystone -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 10Percent MovementLoad (TSF)SwellConsolidatioWater Added