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Home My WebLink AboutFOOTHILLS UNITARIAN CHURCH EXPANSION - FDP210027 - SUBMITTAL DOCUMENTS - ROUND 1 - GEOTECHNICAL (SOILS) REPORTSUBSURFACE EXPLORATION REPORT FOOTHILLS UNITARIAN CHURCH EXPANSION 1815 YORKTOWN AVENUE FORT COLLINS, COLORADO EEC PROJECT NO. 1192097 Prepared for: Foothills Unitarian Church 1815 Yorktown Avenue Fort Collins, Colorado 80526 Attn: Mr. Chris Bettlach (buildingexpansion@foothillsuu.org) 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 December 20, 2019 Foothills Unitarian Church 1815 Yorktown Avenue Fort Collins, Colorado 80526 Attn: Mr. Chris Bettlach (buildingexpansion@foothillsuu.org) Re: Subsurface Exploration Report Foothills Unitarian Church Expansion 1815 Yorktown Avenue Fort Collins, Colorado EEC Project No. 1192097 Mr. Bettlach: Enclosed, herewith, are the results of the subsurface exploration completed by Earth Engineering Consultants, LLC (EEC) for the referenced project. For this exploration, three (3) soil borings were extended to depths of approximately 15 to 25 feet below existing site grades within the proposed development area as depicted on the test boring diagram. Four (4) borings were originally planned; however, boring B-3 was not drilled due to utility conflicts in the general vicinity. This subsurface exploration was carried out in general accordance with our proposal dated July 19, 2019. In summary, the subsurface conditions encountered beneath the surficial vegetation layer, generally consisted of clayey/silty sand with varying amounts of gravel extending to sandy lean clay in borings B-1 and B-2 at depths of approximately 14 to 29 feet below the ground surface and to the depths explored at approximately 10 feet in boring B-4. The clayey/silty sand was generally dry near surface, becoming moist nearing the groundwater table, loose to medium dense, and exhibited low swell potential at current moisture-density conditions. Zones of more granular soil and/or clayey soil were encountered at various depths within the sand soils. The sandy lean clay was generally medium stiff to very stiff. Groundwater was observed in the borings at depths of approximately 14 to 17 feet below the ground surface. Based on the encountered subsurface conditions, in our opinion, the proposed building could be supported on conventional spread footings bearing on approved undisturbed clayey/silty sand or engineered fill soils. Care should be taken to ensure footings are placed on stable and uniform SUBSURFACE EXPLORATION REPORT FOOTHILLS UNITARIAN CHURCH EXPANSION 1815 YORKTOWN AVENUE FORT COLLINS, COLORADO EEC PROJECT NO. 1192097 December 20, 2019 INTRODUCTION The geotechnical subsurface exploration for the proposed Foothills Unitarian Church expansion in Windsor, Colorado has been completed. To develop subsurface information in the proposed development area, three (3) soil borings were drilled to depths of approximately 10 to 30 feet below existing site grades. Boring B-3 was omitted due to utility conflicts in the general vicinity. A diagram indicating the approximate boring locations is included with this report. We understand the proposed development consists of the construction of an administration addition on the northeast side of the existing building and a sanctuary and classroom additions on the southwest side of the building along with associated additional pavements. The administration and classroom additions are expected to be constructed as slab-on-grade (no basement) while the sanctuary portion is expected to be constructed with a potential below grade/basement level. We anticipate maximum foundations loads will be relatively light to moderate with maximum wall and column loads less than 4 klf and 150 kips, respectively. Floor loads are expected to be relatively light. If actual loads exceed those assumed herein, we should be consulted to review and modify the recommendations accordingly, if necessary. Small grade changes are expected to develop site grades for the proposed improvements. The purpose of this report is to describe the subsurface conditions encountered in the test borings, analyze and evaluate the field and laboratory test data and provide geotechnical recommendations concerning design and construction of foundations and floor slabs and support of flatwork and pavements. Recommended pavement sections are also included. EXPLORATION AND TESTING PROCEDURES The test boring locations were selected and established in the field by EEC personnel by pacing and estimating angles from identifiable site features. The approximate locations of the borings are shown on the attached boring location diagram. The boring locations 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. 1192097 December 20, 2019 Page 2 The test borings were advanced 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 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 by means of 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. 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 with unconfined compressive strength of appropriate samples estimated using a calibrated hand penetrometer. Atterberg limits and washed sieve analysis tests were completed on select samples to evaluate the quantity and plasticity of fines in the subgrades. Swell/consolidation testing was completed on select samples to evaluate the potential for the subgrade materials to change volume with variation in moisture content and load. 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 part of the testing program, all samples were examined in the laboratory 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. SITE AND SUBSURFACE CONDITIONS The proposed church building additions are planned for construction at the northeast and southwest sides of the existing church building located at 1815 Yorktown Avenue in Fort Collins, Colorado. The lot is currently vacant. Vegetation and topsoil consisting of sod was encountered at the surface of the borings. Ground surface in this area is relatively flat. Earth Engineering Consultants, LLC EEC Project No. 1192097 December 20, 2019 Page 3 EEC field personnel were 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 results of laboratory testing and evaluation. Based on results of the field borings and laboratory testing, subsurface conditions can be generalized as follows. From the ground surface, the subgrades underlying the existing vegetation described previously consisted of clayey/silty sand with varying amounts of gravel extending to sandy lean clay in borings B-1 and B-2 at depths of approximately 14 to 29 feet below the ground surface and to the depths explored at approximately 10 feet in boring B-4. The clayey/silty sand was generally dry near surface, becoming moist nearing the groundwater table, loose to medium dense, and exhibited low swell potential at current moisture-density conditions. Zones of more granular soil and/or clayey soil were encountered at various depths within the sand soils. The sandy lean clay was generally medium stiff to very stiff. The stratification boundaries indicated on the boring logs represent the approximate location of changes in soil 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, groundwater was observed in the borings at a depth of approximately 14 to 17 feet below the ground surface. The borings were backfilled upon completion of the drilling operations; therefore, subsequent groundwater measurements were not performed. 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. We have typically noted deepest groundwater levels in late winter and shallowest groundwater levels in mid to late summer. Earth Engineering Consultants, LLC EEC Project No. 1192097 December 20, 2019 Page 4 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, relatively undisturbed 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 after the inundation period expressed as a percent of the sample’s preload/initial thickness. After the inundation period, additional incremental loads are applied to evaluate the swell pressure and/or consolidation. For this assessment, we conducted three (3) swell-consolidation tests on relatively undisturbed soil samples obtained at various intervals/depths on the site. The swell index values for the in-situ soil samples analyzed revealed low swell characteristics as indicated on the attached swell test summaries. The (+) test results indicate the soil materials swell potential characteristics while the (-) test results indicate the soils materials collapse/consolidation potential characteristics when inundated with water. The following table summarizes the swell-consolidation laboratory test results for samples obtained during our field explorations for the subject site. TABLE I – Swell/Consolidation 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 Clayey / Silty Sand (SM / SC) 9.1 126.4 500 (-) 0.1 2 4 Clayey Sand (SC) 6.9 140.2 500 (+) 0.0 4 2 Silty Sand (SM) 2.0 112.8 150 (+) 0.3 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. Earth Engineering Consultants, LLC EEC Project No. 1192097 December 20, 2019 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 Based on the laboratory test results, the in-situ samples analyzed for this project were within the low range. Site Preparation Prior to placement of any fill and/or improvements, we recommend any existing vegetation, undocumented fill, flatwork, pavements and any unsuitable materials associated with the existing building’s backfill zone, be removed from the planned improvement areas. Care should be taken to remove any previously placed, undocumented fill material with unknown origin or compaction verification. Care should be taken to avoid disturbing existing foundation bearing materials. Over excavations should be sloped away from the existing foundations to prevent undermining existing foundations. After removal of all topsoil, vegetation, and removal of unacceptable or unsuitable subsoils and prior to placement of fill, 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. Fill materials used to develop site grades, and for foundation backfill should consist of an approved low volume change material, in our opinion, soils similar to the site clayey/silty sand materials or imported granular structural fill material could be used. Imported granular materials should be graded similarly to a CDOT Class 5, 6 or 7 aggregate base. Fill materials should be placed in loose lifts not to exceed 9 inches thick, 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. 1192097 December 20, 2019 Page 6 Care should be exercised after preparation of the subgrades to avoid disturbing the subgrade materials. Materials which are loosened or disturbed should be reworked prior to placement of foundations/flatwork. Foundation System – General Considerations It is our understanding that a portion of the sanctuary addition may be constructed below grade. If, additional footings are constructed at elevations below immediately adjacent existing footings, underpinning the existing footings will be required. We would be pleased to provide additional foundation underpinning recommendations upon request. Footing Foundations Based on materials observed from the test boring locations, it is our opinion that the proposed structures could be supported on conventional footing foundations bearing on approved native undisturbed subsoils or properly placed and compacted fill materials, prepared as recommended in the section Site Preparation. Care should be taken to construct the building additions on uniform bearing to prevent differential movement. For design of footing foundations bearing on suitable strength subsoils or on properly placed fill, we recommend using a net allowable total load soil bearing pressure not to exceed 2,500 psf. The net bearing pressure refers to the pressure at foundation bearing level in excess of the minimum surrounding overburden pressure. Total loads should include full dead and live loads. Exterior foundations and foundations in unheated areas should be located a minimum of 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. Trenched foundations should not be used. No unusual problems are anticipated in completing the excavations required for construction of the footing foundations. Care should be taken during construction to avoid disturbing the foundation bearing materials. 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 prior to placement of foundation concrete. Earth Engineering Consultants, LLC EEC Project No. 1192097 December 20, 2019 Page 7 We estimate the long-term settlement of footing foundations designed and constructed as outlined above would be 1 inch or less. Lateral Earth Pressures Portions of the new structure or site improvements which are constructed below grade may be subject to lateral earth pressures. Passive lateral earth pressures may help resist the driving forces for retaining 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, such as below grade walls for a building. 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 Table III 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 on-site essentially cohesive subsoils. For 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, 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. Table III - Lateral Earth Pressures Soil Type On-Site Overburden Clayey/Silty Sand Soils Imported Medium Dense Granular Material Wet Unit Weight (psf) 115 135 Saturated Unit Weight (psf) 135 140 Friction Angle () – (assumed) 30° 35° Active Pressure Coefficient 0.33 0.27 At-rest Pressure Coefficient 0.50 0.43 Passive Pressure Coefficient 3.00 3.70 Earth Engineering Consultants, LLC EEC Project No. 1192097 December 20, 2019 Page 8 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. Floor Slabs and Exterior Flatwork Subgrades for floor slabs, flatwork and site pavements should be prepared as outlined in the section Site Preparation. For structural design of concrete slabs-on-grade, a modulus of subgrade reaction of 125 pounds per cubic inch (pci) could be used for floors supported on native undisturbed subsoils. Additional floor slab design and construction recommendations are as follows:  Interior partition walls should be separated/floated from floor slabs to allow for independent movement.  Positive separations and/or isolation joints should be provided between slabs and all foundations, columns, and utility lines to allow for 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 should be followed. For interior floor slabs, depending on the type of floor covering and adhesive used, those material manufacturers may require that specific subgrade, capillary break, and/or vapor barrier requirements be met. The project architect and/or material manufacturers should be consulted with for specific under slab requirements. Care should be exercised after development of the floor slab and exterior flatwork subgrades to prevent disturbance of the in-place materials. Subgrade soils which are loosened or disturbed by Earth Engineering Consultants, LLC EEC Project No. 1192097 December 20, 2019 Page 9 construction activities or soils which become wet and softened or dry and desiccated should be removed and replaced or reworked in place prior to placement of the overlying slabs. Seismic The site soil conditions generally consist of clayey/silty sand with varying amounts of gravel underlain by sandy lean clay. For those site conditions, the International Building Codes indicates a Seismic Site Classification of D. Drilling to a greater depth could reveal a different site classification. Pavements Pavement subgrades should be prepared as outlined in the section Site Preparation. We anticipate the site pavements will include areas designated for light-duty automobile traffic as well as some areas for heavier automobile and heavy-duty truck traffic. For design purposes, an assumed equivalent daily load axle (EDLA) rating of 7 is used in the light-duty pavement areas and an EDLA of 15 is used in the heavy-duty pavement areas. Proofrolling and recompacting the subgrade is recommended immediately prior to placement of the aggregate road base section. Soft or weak areas delineated by the proofrolling operations should be undercut or stabilized in-place to achieve the appropriate subgrade support. Based on the subsurface conditions encountered at the site, an assumed R-value of 10 was used in design of the pavement sections. If additional stabilization is required, consideration could be given to a fly ash treatment of the subgrades. The fly ash treatment process would involve incorporating Class C fly ash within the upper 12-inches of the interior roadways subgrade sections from back of curb to back of curb, (in essence the full roadway width), prior to construction of the overlying pavement structure. Stabilization would consist of blending 13% by dry weight of Class C fly ash in the top 12 inches of the subgrades. The blended materials should be adjusted in moisture content to slightly dry of standard Proctor optimum moisture content and compacted to at least 95% of the materials maximum dry density as determined in accordance with the standard Proctor procedure. Compaction of the subgrade should be completed within two hours after initial blending of the Class C fly ash. Earth Engineering Consultants, LLC EEC Project No. 1192097 December 20, 2019 Page 10 Recommended minimum pavement sections are provided below in Table IV. HBP sections may show rutting/distress in truck loading and drive areas; therefore, concrete pavements should be considered in these areas. The recommended pavement sections are considered minimum; thus, periodic maintenance should be expected. Table IV - Recommended Pavement Sections Light Duty Areas Heavy Duty Areas 18-kip EDLA 18-kip ESAL Reliability Resilient Modulus (Based on R-Value=10) PSI Loss 7 51,100 75% 3562 2.5 15 109,500 80% 3562 2.2 Design Structure Number 2.47 2.88 Composite Section – Option A (assume Stable Subgrade) Hot Mix Asphalt Aggregate Base Course Structure Number 4" 7" (2.53) 5" 7" (2.97) Composite Section with Fly Ash Treated Subgrade Hot Mix Asphalt Aggregate Base Course Fly Ash Treated Subgrade (assume half-credit) Structure Number 3-1/2" 6" 12" (2.80) 4" 6" 12" (3.02) PCC (Non-reinforced) – placed on a stable subgrade 5½" 6" We recommend aggregate base meet a CDOT 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. HBP should be graded as SX or S and be prepared with 75 gyrations using a Superpave gyratory compactor in accordance with CDOT standards. The HBP should consist of PG 58-28 or PG 64-22 asphalt binder. HBP should be compacted to achieve 92 to 96% of the mix’s theoretical maximum specific gravity (Rice Value). Portland cement concrete should be an approved exterior pavement mix with a minimum 28-day compressive strength of 4,500 psi and should be air entrained. Wire mesh or fiber could be considered to reduce shrinkage cracking. 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 Earth Engineering Consultants, LLC EEC Project No. 1192097 December 20, 2019 Page 11 pavement geometry. Sawed joints should be cut in general accordance with ACI recommendations. All joints should be sealed to prevent entry of foreign material and dowelled where necessary for load transfer. 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 V - Water Soluble Sulfate Test Results Sample Location Description % of Soil by Weight B-1, S-2, at 4’ Well Graded Sand with Silt (SW – SM) 0.02 B-2, S-2, at 9’ Clayey Sand (SC) 0.01 Based on the results as presented above, ACI 318, Section 4.2 indicates the site soils have a low risk of sulfate attack on Portland cement concrete, therefore, ACI Class S0 requirements should be followed for concrete placed in the silty/clayey sand soils. Foundation concrete should be designed in accordance with the provisions of the ACI Design Manual, Section 318, Chapter 4. Other Considerations Positive drainage should be developed away from the structures 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 (if required) adjacent to the building to avoid features which would pond water adjacent to the 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. Irrigation 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 structures or site pavements. Roof drains should be designed to discharge at least 5 feet away from the structures and away from the pavement areas. Earth Engineering Consultants, LLC EEC Project No. 1192097 December 20, 2019 Page 12 Excavations into the zones of essentially granular silty sand soils have the potential for caving/sloughing side walls. 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. 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 phases to help determine that the design requirements are fulfilled. This report has been prepared for the exclusive use of Foothills Unitarian Church 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. 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 12%1%%%2Boring Location DiagramFoothills Unitarian Church Expansion - Fort Collins, ColoradoEEC Project #: 1192097December 2019EARTH ENGINEERING CONSULTANTS, LLCApproximate BoringLocations1LegendSite PhotosPhotos taNen in approximatelocation, in direction oI arroZNote: B- Not DrilledDue to Utilit\ ConIlict UNITARIAN CHURCH ADDITIONS FORT COLLINS, COLORADO EEC PROJECT NO. 1192097 DECEMBER 2019 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 & TOPSOIL - SOD _ _ 1 CLAYEY / SILTY SAND (SC/SM) _ _ brown / red 2 medium dense _ _ CS 3 23 8000 9.1 124.5 21 5 27.5 < 500 psf None _ _ 4 _ _ SS 5 30 4.9 WELL GRADED SAND with SILT (SW - SM) _ _ brown / red 6 medium dense _ _ 7 _ _ 8 _ _ 9 _ _ CS 10 26 5.1 97.2 11 _ _ 11 _ _ 12 _ _ 13 _ _ 14 _ _ SANDY LEAN CLAY (CL) SS 15 20 3000 8.0 brown / red _ _ very stiff 16 _ _ 17 _ _ 18 ` _ _ 19 _ _ CS 20 25 17.8 113.6 BOTTOM OF BORING DEPTH 20.0' _ _ 21 _ _ 22 _ _ 23 _ _ 24 _ _ 25 _ _ Earth Engineering Consultants, LLC FOOTHILLS UNITARIAN CHURCH EXPANSION FORT COLLINS, COLORADO LOG OF BORING B-1PROJECT NO: 1192097 DECEMBER 2019 SHEET 1 OF 1 WATER DEPTH START DATE 12/9/2019 WHILE DRILLING 17.0' SURFACE ELEV N/A 24 HOUR N/A FINISH DATE 12/9/2019 AFTER DRILLING N/A 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 VEGETATION & TOPSOIL - SOD _ _ 1 CLAYEY SAND (SC) _ _ red 2 medium dense to loose _ _ with gravel 3 _ _ 4 _ _ CS 5 18 2500 6.9 123.8 30 15 17.9 < 500 psf None _ _ 6 _ _ 7 _ _ 8 _ _ 9 red / brown _ _ gravel seam SS 10 21 6.5 _ _ 11 _ _ 12 _ _ 13 _ _ 14 _ _ more clayey from approx 14.5' to 24' CS 15 6 17.2 115.6 _ _ 16 _ _ 17 _ _ 18 _ _ 19 _ _ SS 20 8 20.8 _ _ 21 _ _ 22 _ _ 23 _ _ 24 SAND & GRAVEL (SP & GP) _ _ brown / gray / rust, medium dense CS 25 26 13.1 120.7 Continued on Sheet 2 of 2 _ _ Earth Engineering Consultants, LLC FOOTHILLS UNITARIAN CHURCH EXPANSION FORT COLLINS, COLORADO PROJECT NO: 1192097 LOG OF BORING B-2 DECEMBER 2019 SHEET 1 OF 1 WATER DEPTH START DATE 11/25/2019 WHILE DRILLING 14.0' SURFACE ELEV N/A 24 HOUR N/A FINISH DATE 11/25/2019 AFTER DRILLING N/A 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 Continued from Sheet 1 of 2 26 _ _ SAND & GRAVEL (SP & GP) 27 brown / gray / rust _ _ medium dense 28 _ _ 29 LEAN CLAY (CL) _ _ red SS 30 7 500 26.8 medium stiff _ _ BOTTOM OF BORING DEPTH 30.5' 31 _ _ 32 _ _ 33 _ _ 34 _ _ 35 _ _ 36 _ _ 37 _ _ 38 _ _ 39 _ _ 40 _ _ 41 _ _ 42 _ _ 43 _ _ 44 _ _ 45 _ _ 46 _ _ 47 _ _ 48 _ _ 49 _ _ 50 _ _ Earth Engineering Consultants, LLC FOOTHILLS UNITARIAN CHURCH EXPANSION FORT COLLINS, COLORADO PROJECT NO: 1192097 LOG OF BORING B-2 DECEMBER 2019 SHEET 2 OF 2 WATER DEPTH START DATE 11/25/2019 WHILE DRILLING 14.0' 11/25/2019 AFTER DRILLING N/A SURFACE ELEV 24 HOUR N/A FINISH DATE A-LIMITS SWELL N/A 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 & TOPSOIL - SOD _ _ 1 SILTY SAND (SM) _ _ brown / red 2 medium dense to loose _ _% @ 150 psf CS 3 17 2.0 104.8 NL NP 9.0 350 psf 0.3% _ _ 4 _ _ SS 5 21 3.3 _ _ 6 _ _ 7 _ _ 8 _ _ 9 _ _ SS 10 9 8.6 with occasional clay zones _ _ 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 FOOTHILLS UNITARIAN CHURCH EXPANSION FORT COLLINS, COLORADO PROJECT NO: 1192097 LOG OF BORING B-4 DECEMBER 2019 SHEET 1 OF 1 WATER DEPTH START DATE 11/25/2019 WHILE DRILLING None SURFACE ELEV N/A 24 HOUR N/A FINISH DATE 11/25/2019 AFTER DRILLING N/A A-LIMITS SWELL Project: Location: Project #: Date: Foothills Unitarian Church Expansion Fort Collins, Colorado 1192097 December 2019 Beginning Moisture: 9.1% Dry Density: 126.4 pcf Ending Moisture: 12.3% Swell Pressure: < 500 psf % Swell @ 500: None Sample Location: Boring 1, Sample 1, Depth 2' Liquid Limit: 21 Plasticity Index: 5 % Passing #200: 27.5% SWELL / CONSOLIDATION TEST RESULTS Material Description: Brown / Red Clayey / Silty Sand (SM / 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 10Percent MovementLoad (TSF)SwellConsolidatioWater Added Project: Location: Project #: Date: Foothills Unitarian Church Expansion Fort Collins, Colorado 1192097 December 2019 Beginning Moisture: 6.9% Dry Density: 140.2 pcf Ending Moisture: 11.7% Swell Pressure: < 500 psf % Swell @ 500: None Sample Location: Boring 2, Sample 1, Depth 4' Liquid Limit: 30 Plasticity Index: 15 % Passing #200: 17.9% SWELL / CONSOLIDATION TEST RESULTS Material Description: 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 10Percent MovementLoad (TSF)SwellConsolidatioWater Added Project: Location: Project #: Date: SWELL / CONSOLIDATION TEST RESULTS Material Description: Brown / Red Silty Sand (SM) Sample Location: Boring 4, Sample 1, Depth 2' Liquid Limit: NL Plasticity Index: NP % Passing #200: 9.0% Beginning Moisture: 2.0% Dry Density: 112.8 pcf Ending Moisture: 17.5% Swell Pressure: 350 psf % Swell @ 150: 0.3% Foothills Unitarian Church Expansion Fort Collins, Colorado 1192097 December 2019 -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 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: Foothills Unitarian Church Expansion Location: Fort Collins, Colorado Project No: 1192097 Sample ID: B-1, S-3, at 9' Sample Desc.: Well Graded Sand with Silt and Gravel (SW - SM) Date: December 2019 EARTH ENGINEERING CONSULTANTS, LLC SUMMARY OF LABORATORY TEST RESULTS Sieve Analysis (AASHTO T 11 & T 27 / ASTM C 117 & C 136) 100 Sieve Size Percent Passing 100 100 100 100 93 91 84 72 15 11.0 68 57 40 32 24 0.39 0.08Fine18.33 1.47D30D10CuCCDecember 201919.00 1.37 0.93Foothills Unitarian Church ExpansionFort Collins, Colorado1192097B-1, S-3, at 9'Well Graded Sand with Silt and Gravel (SW - SM)D100D60D50EARTH ENGINEERING CONSULTANTS, LLCSummary of Washed Sieve Analysis Tests (ASTM C117 & C136)Date:Project:Location:Project No:Sample ID:Sample Desc.:CobbleSilt or ClayGravelCoarse FineSandCoarse Medium6"5"4"3"2.5"2"1.5"1"3/4"1/2"3/8"No. 4No. 8No. 10No. 16No. 30No. 40No. 50No. 100No. 20001020304050607080901000.010.11101001000Finer by Weight (%)Grain Size (mm)Standard Sieve Size