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Home My WebLink AboutMAGNOLIA DWELLINGS - PDP200018 - SUBMITTAL DOCUMENTS - ROUND 1 - GEOTECHNICAL (SOILS) REPORTMay 19, 2020 Forge + Bow Dwelling 116 N. College Ave. Fort Collins, Colorado 80524 Attn: Jordan Obermann (jordan@forgeandbow.com) Re: Geotechnical Subsurface Exploration Proposed Multi-Family Residence 335 East Magnolia Street Fort Collins, Colorado EEC Project No. 20-01-080 Mr. Obermann: Earth Engineering Company, Inc. (EEC) personnel have completed the geotechnical subsurface exploration you requested for the proposed multi-family residence to be constructed at 335 East Magnolia Street located in Fort Collins, Colorado. Results of that subsurface exploration are provided with this report. We understand the proposed multi-family residence will be a two-story wood-frame four- plex structure constructed with basements. We expect foundation loads for the structure will be light with continuous wall loads less than 3.0 kips per lineal foot and individual column loads less than 50 kips. Small grade changes are expected to develop final site grades for the structure. The purpose of this report is to describe the subsurface conditions encountered in the test borings completed within the identified building envelope on the site and provide geotechnical recommendations for design and construction of foundations and support of floor slabs and exterior flatwork. The referenced lot is located at 335 East Magnolia Street in Fort Collins, Colorado. The property is presently developed with an existing residence located within the building envelope. To develop information on existing subsurface conditions in the area of the proposed residence, two soil borings were extended to a depth of approximately 20 and 25½ feet Earth Engineering Company, Inc. EEC Project No. 20-01-080 May 19, 2020 Page 2 below present site grades within the approximate building envelope. The locations of the test borings were established by pacing and estimating angles from site property corners and 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. The borings were performed using a truck-mounted, rotary-type 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 Specification D-1586. All samples obtained in the field were sealed and returned to the laboratory for further examination, classification and testing. An EEC field engineer was on site during drilling to evaluate the subsurface conditions encountered and direct the drilling activities. A field boring log was prepared based on observation of disturbed samples and auger cuttings. Based on results of the field boring and laboratory testing, subsurface conditions in the proposed residence location can be generalized as follows: Brown to reddish brown sandy lean clay soils were encountered at the surface at the boring locations. The sandy lean clay soils encountered in the borings were medium stiff to very stiff in consistency and exhibited a low potential for swelling with variation in moisture content at current moisture/density conditions. The moderately plastic sandy lean clay soils were underlain by brown sand and gravel materials at a depth of approximately 12 and 16 feet below present site grades at borings B-1 and B-2, respectively. The essentially granular materials were very dense in consistency, contained cobbles and extended to the bottom of the borings at a depth of approximately 20 and 25½ feet below present site grades. Observations were made at the time of drilling and approximately 48 hours after drilling to evaluate the presence and depth to free water at the test boring locations. At the time of drilling, free water was observed at a depth of approximately 16 and 19 feet below present site grades in the borings completed on this property. Approximately 48 hours after drilling, free water was observed at a depth of approximately 14½ and 18 feet below present site grades at borings B-1 and B-2, respectively. Longer-term observations in holes which are Earth Engineering Company, Inc. EEC Project No. 20-01-080 May 19, 2020 Page 3 cased and sealed from the influence of surface water would be required to more accurately evaluate groundwater levels and possible fluctuations in those groundwater levels over time. Fluctuations in groundwater levels can occur based on hydrologic conditions and other conditions not apparent at the time of this report. Zones of perched and/or trapped water may also be encountered in more permeable zones within the subgrade soils at times throughout the year. The stratification boundaries indicated on the boring logs represent the approximate locations of changes in soil and rock types; in-situ, the transition of materials may be gradual and indistinct. In addition, the soil borings provide an indication of subsurface conditions at the test locations; however, subsurface conditions may vary in relatively short distances away from the borings. Potential variations in subsurface conditions can best be evaluated by close observation and testing of the subgrade materials during construction. If significant variations from the conditions anticipated from the test borings appear evident at that time, it may be necessary to re-evaluate the recommendations provided in this report. ANALYSIS AND RECOMMENDATIONS General It is our understanding the existing residence located at the site will be removed prior to construction of the new multi-family residence. We recommend the existing concrete foundation and any other concrete elements be entirely removed from the existing residence prior to construction of the new structure. Some areas of backfill near the old building and may be encountered during demolition and removal of the structure. We recommend removing those fill materials down to the natural in-situ sandy lean clay soils prior to construction of the new foundations. Foundations Based on the materials observed at the test boring locations, it is our opinion the proposed lightly loaded multi-family residence could be supported on conventional footing foundations bearing in the near surface sandy lean clay soils. For design of footing foundations bearing in the medium stiff to very stiff sandy lean clay soils, we recommend using a net allowable total load soil bearing pressure not to exceed 1,000 psf. The net Earth Engineering Company, Inc. EEC Project No. 20-01-080 May 19, 2020 Page 4 bearing pressure refers to the pressure at foundation bearing level in excess of the minimum surrounding overburden pressure. Total load should include full dead and live loads. Exterior foundations and foundations in unheated areas should be located at least 30 inches below adjacent exterior grade to provide frost cover protection. We recommend formed continuous footings have a minimum width of 12 inches and isolated column foundations have a minimum width of 24 inches. We recommend the foundation footing design loads be balanced to promote relatively uniform settlement, thereby reducing the potential for differential settlement. As an alternative to balancing the design loads solely on settlement, designing the foundation such that the dead-load pressure is balanced throughout the foundations could be considered. Balancing the dead-load pressure would also reduce the potential for differential settlement between adjacent footings. We estimate the long-term movement of footing foundations designed and constructed as recommended above would be less than 1 inch. Groundwater was observed in test boring at a depth of approximately 14½ to 18 feet below present site grades. We recommend maintaining a minimum 3-feet separation between the foundation bearing elevation and peak seasonal groundwater levels. Close observation would be needed to evaluate the groundwater depths during the spring and summer months to determine the peak groundwater levels at the site. While the site cohesive soils did not exhibit appreciable swell potential with variation in moisture content, some consolidation was observed in the near surface samples tested. Close observation and testing will be needed to evaluate the volume change characteristics of the in-situ soils at the time of foundation excavation. If loose or highly compressible soils are observed at that time, reworking of the subgrade or removal and replacement may be necessary to develop suitable foundation bearing. No unusual problems are anticipated in the construction of the footing foundations. Care should be taken to avoid disturbing the bearing soils. The natural site soils may be easily disturbed by construction activities. Soils which are disturbed by the construction activities or materials which have become dry and desiccated or wet and softened should be reworked or removed from the foundation excavation prior to the placement of foundation concrete. Earth Engineering Company, Inc. EEC Project No. 20-01-080 May 19, 2020 Page 5 We estimate the long-term movement of footing foundations designed and constructed as outlined above would be less than 1 inch. Floor Slab and Exterior Slab-on-Grade Subgrades Any existing vegetation and/or topsoil should be removed from floor slab areas. After stripping and completing all cuts and prior to placement of any floor slabs or fill, we recommend the exposed subgrades be scarified to a minimum depth of 9 inches, adjusted in moisture content and compacted to at least 95% of the material's maximum dry density as determined in accordance with ASTM Specification D-698, the standard Proctor procedure. The moisture content of the scarified soils should be adjusted to be within the range of ±2% of standard Proctor optimum moisture at the time of compaction. Fill soils required to develop the floor slab subgrades should consist of approved, low- volume change materials which are free from organic matter and debris. It is our opinion the on-site sandy lean clay soils could be used as low-volume change fill in the floor areas. Those fill materials should be placed in loose lifts not to exceed 9 inches thick, adjusted in moisture content as recommended for the scarified soils and compacted to at least 95% of standard Proctor maximum dry density. After preparation of the subgrades, care should be taken to avoid disturbing the in-place materials. Subgrade materials 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 placement of the floor slab concrete. As a precaution, the floor slabs should be isolated from structural portions of the building to prevent differential movement to those elements causing distress to the structure. In addition, we recommend the floor slab be isolated from non-load bearing partitions to help reduce the potential for slab movement causing distress in upper sections of the building. That isolation is typically developed through the use of a voided wall which is suspended from the overhead first floor joist. Care should be taken in door framing, drywalling and finishing to maintain a voided space which will allow for movement of the floor slab without transmission of stresses to the overlying structure. Earth Engineering Company, Inc. EEC Project No. 20-01-080 May 19, 2020 Page 6 While laboratory testing completed for this report indicated the near surface site soils sampled exhibited relatively low swell potential, floor slab and exterior flatwork movement could occur and should be expected. Slab movement is common in Colorado even in areas with relatively low-swelling soils. Mitigation techniques to reduce the potential for post- construction movement, such as overexcavation, moisture conditioning and replacement could be considered; however, the risk for slab movement cannot be eliminated. Below Grade Areas We recommend an exterior perimeter drain system be installed around all below grade areas to reduce the potential for hydrostatic loads on the below grade walls and to help prevent accumulation of infiltration water in below grade areas. In general, a perimeter drain system should consist of perforated metal or plastic pipe placed at approximate foundation bearing level around the exterior perimeter of the structure. The drainline should be surrounded by a minimum of 6 inches of appropriately sized granular filter soil and either the filter soil or drainline should be surrounded by a filter fabric to help reduce the potential infiltration of fines into the drain system. The drainline should be sloped to provide positive gravity drainage of water to a sump area or gravity outfall where reverse flow cannot occur into the system. Backfill placed adjacent to the below grade walls should consist of approved, low-volume change soils which are free from organic matter and debris. It is our opinion the on-site sandy lean clay soils could be used as low-volume change fill in the floor areas. If free draining granular soils are used as backfill adjacent to the below grade areas, we recommend the top 2 feet of material be an essentially cohesive material to reduce surface infiltration in the backfill. The backfill soils should be placed in loose lifts not to exceed 9 inches thick, adjusted in moisture content and compacted to be within the range of 93% to 98% of the material's maximum dry density as determined in accordance with the standard Proctor procedure. The moisture content of the backfill soils should be adjusted to be within the range of –1% to +3% of standard Proctor optimum moisture. Care should be taken in placing and compacting the wall backfill to avoid placing undue lateral stress on the below grade walls. We recommend compaction using light mechanical or hand compaction equipment. Earth Engineering Company, Inc. EEC Project No. 20-01-080 May 19, 2020 Page 7 For design of below grade walls where appropriate steps have been taken to eliminate hydrostatic loads, we recommend using an equivalent fluid pressure of 50 pounds per cubic foot. The recommended design equivalent fluid pressure is based on an active stress distribution case where slight rotation is expected in the below grade walls. The rotation expected to develop an active stress distribution case results in deflection on the wall of approximately 0.5% times the height of the wall. That deflection may result in stress cracks on the interior of the basement walls, particularly near the center of spans between corners or other restrained points. The recommended equivalent fluid pressure does not include an allowance for hydrostatic loads nor does it include a factor of safety. Surcharge loads placed adjacent to below grade walls or point loads placed in the wall backfill may add to the lateral pressures of below grade walls. Other Considerations Positive drainage should be developed away from the structure with a minimum slope of 1 inch per foot for the first 10 feet away from the building. Care should be taken in planning of landscaping adjacent to the residence to avoid features which would pond water adjacent to the foundations or stemwalls. Placement of plants which require irrigation system or could result in fluctuations of the moisture content of the subgrade material should be avoided adjacent to the structure. Lawn watering systems should not be placed within 5 feet of the perimeter of the building and spray heads should be designed not to spray water on or immediately adjacent to the structure. Roof drains should be designed to discharge at least 5 feet away from the structure and away from the pavement areas. In developing the site grades, care should be taken to avoid placement of expansive soils beneath site pavements or other improvements. Higher plasticity site materials could be used in non-structural support areas on the site. 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 across the site. The nature and extent of such variations may not become evident Earth Engineering Company, Inc. EEC Project No. 20-01-080 May 19, 2020 Page 8 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 Forge + Bow Dwelling 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. We appreciate the opportunity to be of service to you on this project. If you have any questions concerning this report, or if we can be of further service to you in any other way, please do not hesitate to contact us. Very truly yours, Earth Engineering Company, Inc. Michael J. Coley, P.E. Principal Engineer cc: Alex Henze (alex@forgeandbow.com) 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: 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 Silts and Clays Liquid Limit 50 or more 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 335 EAST MAGNOLIA ST. FORT COLLINS, CO EEC PROJECT No. 20-01-080 MAY 2020 335 EAST MAGNOLIA STREET FORT COLLINS, COLORADO PROJECT NO: 20-01-080 DATE: MAY 2020 LOG OF BORING B-1 RIG TYPE: CME55 SHEET 1 OF 1 WATER DEPTH FOREMAN: SM START DATE 5/5/2020 WHILE DRILLING 16' AUGER TYPE: 4" CFA FINISH DATE 5/5/2020 AFTER DRILLING 16' SPT HAMMER: AUTO SURFACE ELEV N/A 48 HOUR 14.5' SOIL DESCRIPTION D N QU MC DD A-LIMITS -200 SWELL TYPE (FEET) (BLOWS/FT) (PSF) (%) (PCF) LL PI (%) PRESSURE % @ 500 PSF _ _ SANDY LEAN CLAY (CL) 1 brown _ _ very stiff 2 silty _ _ CS 3 7 9000+ 8.7 113.0 < 500 psf None _ _ 4 _ _ CS 5 13 9000+ 11.6 110.3 < 500 psf None _ _ 6 _ _ reddish brown 7 _ _ 8 _ _ 9 brown _ _ CS 10 17 9000 18.0 111.8 38 27 90.8 1000 psf 0.3% _ _ 11 _ _ 12 _ _ SAND AND GRAVEL (SP-GP) 13 brown _ _ very dense 14 with cobbles _ _ SS 15 50/8" -- 5.9 _ _ 16 _ _ 17 _ _ 18 _ _ 19 _ _ SS 20 50 -- 18.4 20' BOTTOM OFBORING _ _ 21 _ _ 22 _ _ 23 _ _ 24 _ _ 25 335 EAST MAGNOLIA STREET FORT COLLINS, COLORADO PROJECT NO: 20-01-080 DATE: MAY 2020 LOG OF BORING B-2 RIG TYPE: CME55 SHEET 1 OF 1 WATER DEPTH FOREMAN: SM START DATE 5/5/2020 WHILE DRILLING 19' AUGER TYPE: 4" CFA FINISH DATE 5/5/2020 AFTER DRILLING 19' SPT HAMMER: AUTO SURFACE ELEV N/A 48 HOUR 18' SOIL DESCRIPTION D N QU MC DD A-LIMITS -200 SWELL TYPE (FEET) (BLOWS/FT) (PSF) (%) (PCF) LL PI (%) PRESSURE % @ 500 PSF _ _ SANDY LEAN CLAY (CL) 1 brown _ _ medium stiff 2 silty _ _ 3 _ _ 4 _ _ CS 5 4 6000 13.3 104.8 < 500 psf None _ _ 6 _ _ 7 _ _ 8 _ _ 9 reddish brown _ _ very stiff CS 10 13 9000+ 13.7 112.3 < 500 psf None _ _ 11 _ _ 12 _ _ 13 _ _ 14 brown _ _ CS 15 24 8000 14.2 116.7 < 1000 psf None@1000 _ _ 16 _ _ SAND AND GRAVEL (SP-GP) 17 brown _ _ very dense 18 with cobbles _ _ 19 _ _ SS 20 50/10" -- 9.1 _ _ 21 _ _ 22 _ _ 23 _ _ 24 _ _ 25.5' BOTTOM OF BORING SS 25 50/7" -- 13.1 SWELL / CONSOLIDATION TEST RESULTS Material Description: Dark Brown Sandy Lean Clay Sample Location: B-1, S-1 @ 2' Liquid Limit: -- Plasticity Index: -- % Passing #200: -- Beginning Moisture: 8.8% Dry Density: 113.0 pcf Ending Moisture: 17.1% Swell Pressure: < 500 psf % Swell @ 500 psf: None Project: 335 East Magnolia Street Fort Collins, Colorado Project No.: 20-01-080 Date: May 2020 -10 -8 -6 -4 -2 0 2 4 6 8 10 0.01 0.1 1 10 Percent Movement Load (TSF) Water Added Consolidation Swell SWELL / CONSOLIDATION TEST RESULTS Material Description: Dark Brown Sandy Lean Clay Sample Location: B-1, S-2 @ 4' Liquid Limit: -- Plasticity Index: -- % Passing #200: -- Beginning Moisture: 9.2% Dry Density: 110.3 pcf Ending Moisture: 16.1% Swell Pressure: < 500 psf % Swell @ 500 psf: None Project: 335 East Magnolia Street Fort Collins, Colorado Project No.: 20-01-080 Date: May 2020 -10 -8 -6 -4 -2 0 2 4 6 8 10 0.01 0.1 1 10 Percent Movement Load (TSF) Water Added Consolidation Swell SWELL / CONSOLIDATION TEST RESULTS Material Description: Brown Sandy Lean Clay Sample Location: B-1, S-3 @ 9' Liquid Limit: 38 Plasticity Index: 27 % Passing #200: 90.8 Beginning Moisture: 18.4% Dry Density: 111.8 pcf Ending Moisture: 19.8% Swell Pressure: 1000 psf % Swell @ 500 psf: 0.3% Project: 335 East Magnolia Street Fort Collins, Colorado Project No.: 20-01-080 Date: May 2020 -10 -8 -6 -4 -2 0 2 4 6 8 10 0.01 0.1 1 10 Percent Movement Load (TSF) Water Added Consolidation Swell SWELL / CONSOLIDATION TEST RESULTS Material Description: Brown Sandy Lean Clay Sample Location: B-2, S-1 @ 4' Liquid Limit: -- Plasticity Index: -- % Passing #200: -- Beginning Moisture: 12.4% Dry Density: 104.8 pcf Ending Moisture: 19.8% Swell Pressure: < 500 psf % Swell @ 500 psf: None Project: 335 East Magnolia Street Fort Collins, Colorado Project No.: 20-01-080 Date: May 2020 -10 -8 -6 -4 -2 0 2 4 6 8 10 0.01 0.1 1 10 Percent Movement Load (TSF) Water Added Consolidation Swell SWELL / CONSOLIDATION TEST RESULTS Material Description: Reddish Brown Sandy Lean Clay Sample Location: B-2, S-2 @ 9' Liquid Limit: -- Plasticity Index: -- % Passing #200: -- Beginning Moisture: 16.3% Dry Density: 112.3 pcf Ending Moisture: 17.1% Swell Pressure: < 500 psf % Swell @ 500 psf: None Project: 335 East Magnolia Street Fort Collins, Colorado Project No.: 20-01-080 Date: May 2020 -10 -8 -6 -4 -2 0 2 4 6 8 10 0.01 0.1 1 10 Percent Movement Load (TSF) Water Added Consolidation Swell SWELL / CONSOLIDATION TEST RESULTS Material Description: Brown Sandy Lean Clay Sample Location: B-2, S-3 @ 14' Liquid Limit: -- Plasticity Index: -- % Passing #200: -- Beginning Moisture: 14.4% Dry Density: 116.7 pcf Ending Moisture: 16.9% Swell Pressure: < 1000 psf % Swell @ 1000 psf: None Project: 335 East Magnolia Street Fort Collins, Colorado Project No.: 20-01-080 Date: May 2020 -10 -8 -6 -4 -2 0 2 4 6 8 10 0.01 0.1 1 10 Percent Movement Load (TSF) Water Added Consolidation Swell Earth Engineering Company Earth Engineering Company 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 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 Silts and Clays Liquid Limit less than 50 IIf soil contains >15% gravel, add "with gravel" to group name JIf Atterberg limits plots shaded area, soil is a CL- ML, Silty clay GIf fines classify as CL-ML, use dual symbol GC- CM, or SC-SM. 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 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 Earth Engineering Company