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Home My WebLink AboutWELLS FARGO PARKING LOT AND ATMS - FDP200016 - SUBMITTAL DOCUMENTS - ROUND 2 - GEOTECHNICAL (SOILS) REPORTSoilogic, Inc. 3522 Draft Horse Court  Loveland, CO 80538  (970) 535-6144 August 27, 2020 Coffey Engineering & Surveying 4045 St. Cloud Drive, Suite 180 Loveland, Colorado 80538 Attn: Mr. Ramsey Pickard, P.E. Re: Geotechnical Subsurface Exploration Wells Fargo Parking Lot Drywell 112 West Magnolia Street Fort Collins, Colorado Soilogic Project # 16-1181 Mr. Pickard: Soilogic, Inc. (Soilogic) personnel have completed the geotechnical subsurface exploration you requested for the proposed dry well to be constructed at the Wells Fargo Parking Lot, located at 112 West Magnolia Street in Fort Collins, Colorado. Results of our subsurface exploration and estimated infiltration rates are included with this report. To develop subsurface information in the proposed dry well area, one (1) soil boring was extended to a depth of approximately 25 feet below present site grade. The boring location was premarked in the field by surveyors. A diagram indicating the approximate boring location is included with this report. A graphic log of the auger boring is also included. The test hole was advanced using 4-inch diameter continuous flight auger powered by a truck-mounted CME-45 drill rig. Samples of the subsurface materials were obtained at regular intervals using California barrel sampling procedures in general accordance with ASTM specification D-1586. As part of the D-1586 sampling procedure, the standard sampling barrel is driven into the substrata using a 140-pound hammer falling a distance of 30 inches. The number of blows required to advance the sampler a distance of 12 inches is recorded and helpful in estimating the consistency or relative density of the soils encountered. In the California barrel sampling procedure, lesser disturbed samples are obtained in removable brass liners. Samples of the subsurface materials obtained in the field were sealed and returned to the laboratory for further evaluation, classification and testing. Geotechnical Subsurface Exploration Report Wells Fargo Parking Lot Drywell 112 West Magnolia Street, Fort Collins, Colorado Soilogic # 16-1181 2 The samples collected were tested in the laboratory to measure natural moisture content and visually and/or manually classified in accordance with the Unified Soil Classification System (USCS). The USCS group symbols are indicated on the attached boring log. An outline of the USCS classification system is included with this report. As part of the laboratory testing, a calibrated hand penetrometer (CHP) was used to estimate the unconfined compressive strength of essentially-cohesive specimens. The CHP also provides a more reliable estimate of soil consistency than tactual observation alone. Dry density and -200 wash tests were completed on selected samples to help establish specific soil characteristics. Atterberg limits tests are used to determine soil plasticity. The percent passing the #200 size sieve (-200 wash) test is used to determine the percentage of fine-grained materials (clay and silt) in a sample. The results of the completed laboratory tests are outlined on the attached boring log. SUBSURFACE CONDITIONS The subsurface materials encountered in the completed site boring can be summarized as follows. Approximately 6 inches of gravel surfacing was encountered at the surface at the boring location. The gravel surfacing was underlain by brown to reddish brown sandy lean clay. The lean clay varied from soft to stiff in terms of consistency and extended to a depth of approximately 17 feet below ground surface where it was underlain by apparently alluvial reddish brown silty sand and gravel. The sand and gravel varied from medium dense to dense in terms of relative density and extended to the bottom of boring B-1 at a depth of approximately 25 feet below present site grade. Groundwater was encountered in the completed site boring at a depth of approximately 22½ feet below ground surface at the time of drilling. When checked about 2 days after completion of drilling, groundwater was measured at a depth of approximately 21½ feet below grade. Groundwater levels will vary seasonally and over time based on weather conditions, site development, irrigation practices and other hydrologic conditions. Perched and/or trapped groundwater conditions may also be encountered at times throughout the year. Perched water is commonly encountered in soils overlying less permeable soil layers and/or bedrock. Trapped water is typically encountered within Geotechnical Subsurface Exploration Report Wells Fargo Parking Lot Drywell 112 West Magnolia Street, Fort Collins, Colorado Soilogic # 16-1181 3 more permeable zones of layered soil and bedrock systems. The location and amount of perched/trapped water can also vary over time. Outlined below in Table 1 is the estimated saturated permeability rate (Ksat) of the subgrade soils identified in our boring based upon grain-size distribution and in-situ density. TABLE 1: SUMMARY OF ESTIMATED PERMEABILITY RATES Depth (ft) Soil Type Estimated Permeability Rate (cm/sec) ½-17 Sandy Lean Clay 1 X 10-5 17-25 Silty Sand and Gravel 0.005 We appreciate the opportunity to be of service to you on this project. If we can be of further service to you in any way or if you have any questions concerning the enclosed information, please do not hesitate to contact us. Very Truly Yours, Soilogic, Inc. Reviewed by: Wolf von Carlowitz, P.E. Darrel DiCarlo, P.E. Principal Engineer Senior Project Engineer 36746 44271 LOG OF BORING B-1 1/1 CME 45 4" CFA Automatic JL/BM Estimated Swell % Passing SOIL DESCRIPTION Depth "N" MC DD qu % Swell @ Pressure # 200 Sieve (ft) (%) (pcf) (psf) 500 psf (psf) LL PI (%) GRAVEL SURFACING - 1 - 2 - CL SANDY LEAN CLAY 3 CS 13 10.3 127.6 9000+ - - - - - brown to reddish brown - soft to stiff 4 - 5 CS 5 8.0 109.2 9000+ - - - - - - 6 - 7 - 8 - 9 - 10 CS 7 10.4 115.5 9000+ - - 28 14 73.1% - 11 - 12 - 13 - 14 - 15 CS 18 17.7 129.4 9000+ - - - - - - 16 - 17 - 18 - SM-GM SILTY SAND AND GRAVEL 19 reddish brown - medium dense to dense 20 CS 50 6.0 - N/A - - - - 20.2% - 21 - 22 - 23 - 24 - BOTTOM OF BORING 25' 25 CS 35 4.8 - N/A - - - - 7.9% Sampler UNIFIED SOIL CLASSIFICATION SYSTEM Criteria for Assigning Group Symbols and Group Names Using Laboratory TestsA Soil Classification Group Symbol Group NameB Clean Gravels Cu ! 4 and 1 " Cc " 3E GW Well graded gravelF Less than 5% finesC Cu < 4 and/or 1 > Cc > 3E GP Poorly graded gravelF Fines classify as ML or MH GM Silty gravelF,G, H Coarse Grained Soils More than 50% retained on No. 200 sieve Gravels More than 50% of coarse fraction retained on No. 4 sieve Gravels with Fines More than 12% finesC Fines classify as CL or CH GC Clayey gravelF,G,H Clean Sands Cu ! 6 and 1 " Cc " 3E SW Well graded sandI Less than 5% finesD Cu < 6 and/or 1 > Cc > 3E SP Poorly graded sandI Fines classify as ML or MH SM Silty sandG,H,I Sands 50% or more of coarse fraction passes No. 4 sieve Sands with Fines More than 12% finesD Fines classify as CL or CH SC Clayey sandG,H,I Silts and Clays PI > 7 and plots on or above “A” lineJ CL Lean clayK,L,M Liquid limit less than 50 Inorganic PI < 4 or plots below “A” lineJ ML SiltK,L,M Liquid limit - oven dried Organic clayK,L,M,N Fine-Grained Soils 50% or more passes the No. 200 sieve Organic Liquid limit - not dried < 0.75 OL Organic siltK,L,M,O Inorganic PI plots on or above “A” line CH Fat clayK,L,M Silts and Clays Liquid limit 50 or more PI plots below “A” line MH Elastic siltK,L,M Organic Liquid limit - oven dried Organic clayK,L,M,P Liquid limit - not dried < 0.75 OH Organic siltK,L,M,Q Highly organic soils Primarily organic matter, dark in color, and organic odor PT Peat A Based on the material passing the 3-in. (75-mm) sieve B If field sample contained cobbles or boulders, or both, add “with cobbles or boulders, or both” to group name. C Gravels with 5 to 12% fines require dual symbols: GW-GM well graded gravel with silt, GW-GC well graded gravel with clay, GP-GM poorly graded gravel with silt, GP-GC poorly graded gravel with clay. D Sands with 5 to 12% fines require dual symbols: 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 E Cu = D60/D10 Cc = GENERAL NOTES DRILLING & SAMPLING SYMBOLS: SS: Split Spoon - 1⅜" I.D., 2" O.D., unless otherwise noted HS: Hollow Stem Auger ST: Thin-Walled Tube – 2.5" O.D., unless otherwise noted PA: Power Auger RS: Ring Sampler - 2.42" I.D., 3" O.D., unless otherwise noted HA: Hand Auger CS: California Barrel - 1.92" I.D., 2.5" O.D., unless otherwise noted RB: Rock Bit BS: Bulk Sample or Auger Sample WB: Wash Boring or Mud Rotary The number of blows required to advance a standard 2-inch O.D. split-spoon sampler (SS) the last 12 inches of the total 18-inch penetration with a 140-pound hammer falling 30 inches is considered the “Standard Penetration” or “N-value”. For 2.5” O.D. California Barrel samplers (CB) the penetration value is reported as the number of blows required to advance the sampler 12 inches using a 140-pound hammer falling 30 inches, reported as “blows per inch,” and is not considered equivalent to the “Standard Penetration” or “N-value”. 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 Casing Removal Water levels indicated on the boring logs are the levels measured in the borings at the times indicated. Groundwater levels at other times and other locations across the site could vary. In pervious soils, the indicated levels may reflect the location of groundwater. In low permeability soils, the accurate determination of groundwater levels may not be possible with only short-term observations. DESCRIPTIVE SOIL CLASSIFICATION: Soil classification is based on the Unified Classification System. Coarse Grained Soils have more than 50% of their dry weight retained on a #200 sieve; their principal descriptors are: boulders, cobbles, gravel or sand. Fine Grained Soils have less than 50% of their dry weight retained on a #200 sieve; they are principally 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 in-place relative density and fine-grained soils on the basis of their consistency. FINE-GRAINED SOILS COARSE-GRAINED SOILS BEDROCK (CB) Blows/Ft. (SS) Blows/Ft. Consistency (CB) Blows/Ft. (SS) Blows/Ft. Relative Density (CB) Blows/Ft. (SS) Blows/Ft. Consistency < 3 0-2 Very Soft 0-5 < 3 Very Loose < 24 < 20 Weathered 3-5 3-4 Soft 6-14 4-9 Loose 24-35 20-29 Firm 6-10 5-8 Medium Stiff 15-46 10-29 Medium Dense 36-60 30-49 Medium Hard 11-18 9-15 Stiff 47-79 30-50 Dense 61-96 50-79 Hard 19-36 16-30 Very Stiff > 79 > 50 Very Dense > 96 > 79 Very Hard > 36 > 30 Hard RELATIVE PROPORTIONS OF SAND AND GRAVEL GRAIN SIZE TERMINOLOGY Descriptive Terms of Other Constituents Percent of Dry Weight Major Component of Sample Particle Size Trace < 15 Boulders Over 12 in. (300mm) With 15 – 29 Cobbles 12 in. to 3 in. (300mm to 75 mm) Modifier > 30 Gravel 3 in. to #4 sieve (75mm to 4.75 mm) Sand Silt or Clay #4 to #200 sieve (4.75mm to 0.075mm) Passing #200 Sieve (0.075mm) RELATIVE PROPORTIONS OF FINES PLASTICITY DESCRIPTION Descriptive Terms of Other Constituents Percent of Dry Weight Term Plasticity Index Trace With Modifiers < 5 5 – 12 > 12 Non-plastic Low Medium High 0 1-10 11-30 30+ F If soil contains ! 15% sand, add “with sand” to group name. G If fines classify as CL-ML, use dual symbol GC-GM, or SC-SM. HIf fines are organic, add “with organic fines” to group name. I If soil contains ! 15% gravel, add “with gravel” to group name. J If Atterberg limits plot in shaded area, soil is a CL-ML, silty clay. K If soil contains 15 to 29% plus No. 200, add “with sand” or “with gravel,” whichever is predominant. L If soil contains ! 30% plus No. 200 predominantly sand, add “sandy” to group name. M If soil contains ! 30% plus No. 200, predominantly gravel, add “gravelly” to group name. N PI ! 4 and plots on or above “A” line. O PI < 4 or plots below “A” line. P PI plots on or above “A” line. Q PI plots below “A” line. USCS Surface Elev. 22.5' Auger Type: Drilling Rig: Hammer Type: Field Personnel: 7/29/2020 - Water Depth Information 7/29/2020 22.5' FORT COLLINS, COLORADO Project # 16-1181 August 2020 WELLS FARGO PARKING LOT DRYWELL Atterberg Limits 21.5' During Drilling After Drilling Sheet Start Date Finish Date 2 Days After Drilling