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Home My WebLink AboutSWIFT ADDITION TO FOSSIL LAKE P.U.D. - COUNTY REFERRAL - 33-01(I) - SUBMITTAL DOCUMENTS - ROUND 1 - GEOTECHNICAL (SOILS) REPORT• FORT COLLINS, COLORADO PROJECT NO: 1962020 DATE: MARCH 1996 RIG TYPE: CME45 LOG OF BORING B•23 FOREMAN: SH SHEET 1 OF 1 WATER DEPTHSTART AUGER TYPE: 4' CFA DATE O3IIil96 WHILE DRILLING 11.0' SPT HAMMER: MANUAL FINISH DATE 03/27796 AFTER DRILLING 11.0' SURFACE ELEV NIA 24 HOUR NIA SOILDESCRIPTION D N Du MC DD -no SWELL LL PI PRESSURE %Q 300 P3F TYpE (FEET) (BLOW31F7) 1p3F) 1%IIPCF7+_�A4�JMIT"3 (%) 6' TOPSOIL/VEGETATION 1 SILTY SANDY LEAN CLAY 2 brown stiff to soft 3 ISS 4 9 13500 19.1 5 more sand with depth 6 7 8 9 Fss 10 2 25.7 11 12 13 14 SS 15 6 •2500 22.7 16 BOTTOM OF BORING 15.5' 17 i 18 19 20 21 22 23 24 25 Earth Engineerinq Consultants FOSSIL CREEK PRELIMINARY " FORT COLLINS; COLORADO - PROJECT NO:.1962027 DATE: MARCH 1996 ' LOG OF BORING 8.22 RIG TYPE: CME45 SHEET 1 OF 1 WATER DEPTH FOREMAN: SH START DATE 03122t96 WHILE DRILLING 11.5' AUGER TYPE: 4" CFA FINISH DATE 03122/96 AFTER DRILLING 11.5' SPT HAMMER: MANUAL SURFACE ELEV WA 24 HOUR NIA SOIL DESCRIPTION O N cU Mc oo AIIMITS •200 SWELL U. P1 PRESSURE %Q Sea PSF TYPE 1FEETI (BLowswn (Psn (%) IPCF) I%) 6" TOPSOIWEGETATION 1 2 SILTY LEAN CLAY (CL) 3 tan _ soft FSS 4 3 '2500 26.8 5 8 7 SILTY SANDY LEAN CLAY (CL) 4 '1500 19.8 brown SS 8 soft to still 9 10 coarser sand and gravel with depth 11 12 FSS 13 14 9 '500 19.5 BOTTOM OF BORING 13.5' 15 16 17 18 19 20 21 22 23 24 25 Earth Engineering Consultants FOSSIL CREEK PRELIMINARY FORT COLLINS, COLORADO PROJECT NO: 1962023 - - - DATE: MARCH 1996 LOG OF BORING B•21 RIG TYPE: CME45 SHEET 1 OF 1 WATER DEPTH FOREMAN: SH START DATE 03/22/96 WHILE DRILLING 12.5' AUGER TYPE: 4- CFA FINISH DATE 03/22/96 AFTER DRILLING 12.5' SPT HAMMER: MANUAL SURFACE ELEV N/A 24 HOUR WA SOIL DESCRIPTION D N ou 1Fc OD AL611TS •20o SWELL LL PI PRESSURE %Q $00 PSF TYPE (FEET) (BLOWSIFn IP7F) (%) (PCF) (%) 6- TOPSOIL/VEGETATION I SILTY SANDY LEAN CLAY (CL) 2 brown/tan/red stiff 3 ESS 4 14 •6500 26.7 5 coarser sand with depth 6 softer with depth 7 8 9 Fss 10 16 •4500 17.4 11 12 13 14 f ss 1s a 1500 21.6 16 BOTTOM OF BORING 15.5' 17 18 19 20 21 22 23 24 25 Earth Engineering Consultants FOSSIL CREEK PRELIMINARY- z. FORT COLLINS,'COLORADO--, PRCJECT NO: 1962023 DATE: MARCH'1996 LOG OF BORING B-20 SHEET 1 OF 1 " RIG TYPE: CME45 SHEET 1 OF 1 WATER DEPTH FOREMAN: SH START DATE 03/22/96 WHILE DRILLING None AUGER TYPE: 4' CFA FINISH DATE O0122196 AFTER DRILLING None SPT HAMMER: MANUAL SURFACE ELEV N/A 24 HOUR WA SOIL DESCRIPTION 0 N Ou Md DO A4JMITS .200 SWELL U. PI PRESSURE %@ 500 PSF TYPE (FEET) ISLOWS/FT) (PSF) I%) (Pcn 1%) 6' TOPSOI W EGETATION 1 2 SS 5 25 19000+ 17.2 SILTY SANDY LEAN CLAY (CL) dark brown 4 very stiff to stiff 10 •7000 22.0 SS E 5 6 more sand with depot 7 ' 6 9 10 SS 11 12 7 22.4 BOTTOM OF BORING 11.5' 17 14 15 16 17 16 19 20 21 22 29 24 25 Earn Engineering Consultants 0 0 E 0 BORING LOCATION DIAGRAM LOUIS SWIFT Pr,. -,:::EL @ FG SIL CREEK ESTATES LARIMER COUNTY, COLORADO PROJECT NO: 1962023A DATE: MARCH 1999 7 IJN7IDED SOML C LASSIECATION SYSTEM Soil Classification Criteria for Assigning Group Symbols and Group names Using Laboratory Tests Group Group Name Symbol Coarse-Groined Grovels more than Clean Gravels Less Soils more than 50% of coarse than 5% fines Cu>4 and <Cc<3E GW Well -graded 50% retained on froction retained grovel` No. 200 sieve on No. 4 sieve Cu<4 and/or 1>Cc>3` GP Poorly-groded grovel` Grovels with Fines Fines classify as ML or MH GM Silty gravel, G,H more than 12% fines Fines classify as CL or CH GC Clayey Gravel Sands 50% or Clean Sand's Less Cu>6 and 1<Cc<3` SW Well-groded sand' more coarse than 5% fines froction posses Cu<6 and/or 1>CC>3E Sp Poorly -graded sand' No. 4 sieve Sands with Fines Fines classify as ML or MH SM Silty sand'"'' more than 12% fines -Fines classify as CL or CH SC Clayey sand"' Fine -Grained Silts and Clays inorganic PI>7 and plots on or above "A"Line' CL Lean cloy Soils 50% or Liquid Limit less more passes the than 50 PI0 or plots below "A Ain e' ML Silt`'`" No. 200 sieve organic Liquid Limit - oven dried Organic clay"t-U." <0.75 OL Liquid Limit - not dried Organic silt",40 Silts and Clays - inorganic PI plots on or above "Aline CH Fat clay " Liquid Limit 50 or more PI plots below "A"Line MH Elastic Silt""' organic Liquid Limit - oven dried Organic cloy"'`"' <0.75 OH Liquid Limit - not dried Organic silt""a Highly organic soils Primarily organic matter, dark in color, and organic odor PT Peat "Based on the material passing the 3-in. (75- mm) sieve ECu=D �D Cc= (Dx) 1i0 I _"If soil contains 15 to 297._plus No. 200. odtl "with elf field sample contained cobbles or boulders, D % D with sand or gravel WhiChevef is predominant. or both, add -with cobbles or boulders, or both' 4f soil contains 2 30- plus No. 200 to group name. - CGrovels witn 5 to 12% fines required dual Fit soil contains 215% send, add -with send'to Predominantly sand, odtl sandy to group name. Symbols: GW-GM well graded gravel with silt group name. elf fines classify as CL-ML, use duol symbol "If soil conteins 2 30% plus No. 200 'gravely" Gw-GC wen -graded gravel with clay CC -CM, or SC-SM. 'It predomincnlly gravel, odd to group GP -GM poorly -graded gravel with fines are organic. odtl"with organic fines'to group name Name. PI>4 and plots or+ or above .A_ line. GP -GC ands poorly -graded grovel with clay clo Sands with 5 l0 12% fines require dual 'If soil contains >157.grovel, odd"with grovel' pPIS4 or plots below "A" line. Pi on or above "A line. Symbols: SW-SM well-groded sand with silt to group name. +If Atlerberg limits plots shaded area, soil is o plots OPl plots below "A' line. SW -SC well -graded send with clay CL-ML, city cloy. SP-SM poorly graded sand with silt SP-SC poorly graded sand with cloy so, -- For Class;l;cct;On of fine-grained soils and fine-gre,ol , Iroction of C.o", , grC;n Cd SC�19 1 , 50: Eaue Gan of 'A'-I;ne "CrirdntCI al Pb6 to LL-25.5. Inen PI-0.23 (LL-20) V j dEouotton "U"-fine o' c0_ Vertical ct LL-16 to PI=7, JC Inen P1=C g (LL-e) U L , I On20L 10� < ,, Gam° OR O�j--I MII - to - I CL-MU j 0 40 SO 60 70 90 90 '00 .. .. J LIQUID LIMIT (ILL) DRILLING AND EXPLORATION DRILLING & SAMPLING SYMBOLS SS: Split Spoon - 13/8" l.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: Anger 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 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 AI3 : 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 indicate levels may reflect the location of around water. In low permeability soils, the accurate determination of ground water levels is n 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 4200 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 - 1000 Medium 3.001 - 4,000 Stiff 4.001 - 8,000 Very Stiff' 8.001 - 16.000 Very Hard RIiLA HVE DENSITY OF COARSE -GRAINED SOILS N-Blows/ft Relative Densit 0-; Very Loose 4-9 Loose 10-29 Medium Dense 0-49 Dense �0-80 Very Dense 80 - Estremel Dense PHYSICAL PROPERTIES OF BEDROCK DEGREE OF WEATHERING Slight Slight decomposition of parent material o joints. May be color change. Moderate Some decomposition and color chang throughout. High Rock highly decomposed, may be extremel broken. HARDNESS AND DEGREE OF CEMENTATION: Limestone and Dolomite: Hard t tcult 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 b scratched with fingernail. Moderately Can be scratched with fingernail. (lard Soft Can be easily dented but not molded wit fingers. Sandstone and Conglomerate: e Capable of scratching a knife blade. Cemented Cemented Can be scratched with knife. Poorlv Can be broken apart easily with titigers. Earth Engineering Consultants, Inc. EEC Project No. 1962023a March 23, 1999 Page 7 changes are reviewed and the conclusions of this report modified or verified in writing by the geotechnical engineer. M. EEC Project No. 1962023a March 23, 1999 Page 6 Earth Engineering Consultants, Inc. TABLE I: RECOMMENDED PAVEMENT SECTIONS Pavement Materials Local Streets Collector Streets A) Composite Section Surface Asphalt 3'/2 " 4" Aggregate Base 6" 81, 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 discusses' in this report. This report does not reflect any variations which may occur between bor::;s 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 aeotechnical recommendations in the design and specifications. It is further recommended that the geotechr.ical engineer be retained for testing and observations daring earthwork and foundation cons t;:_ctii;:I phases to help determine that the design requirements are fulfilled. This report has been prepared for the exclusive use of Everitt Companies for specific application to the project discussed and has been prepared in accordance with generally accepted ger:;:!::, 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 I EEC Project No. 1962023a March 23, 1999 Page 5 Earth Engineering Consultants. Inc. The site cohesive and essentially. granular soils have low plasticity. It is our opinion those materials could be used as backfill adjacent to below grade structures. Floor Slab and Pavement Subgrades At -grade floor slabs and pavements could be supported directly on the natural site soils. Basement floor slabs could also be supported on natural site soils. Existing vegetation and/or topsoil should be removed from the floor slab and pavement areas. Scarification and recompaction of the exposed materials will be required at the time of construction. Necessary adjustment of the moisture content will vary throughout the year. Positive drainage should be developed across and away from the pavement edges and away from the residential structures. Water allowed to pond on or adjacent to the pavements can result in premature failure of the pavement section. Unacceptable performance of floor slabs and foundations can occur when water is allowed to pond on or adjacent to the structures. Pavements We anticipate the traffic on site pavements would generally be limited to automobiles and light trucks. The near surface soil has a moderately support carrying capacity and as with many of the silty clayey materials in this area, may be subject to instability and strength loss when wetted. Depending on the type of year when the construction occurs, stabilization of the subgrades may be desirable to develop stable subgrades for the pavements. Preliminary pavement sections based on potential roadway classifications are shown below in Table 1. Those sections are based on City of Fort Collins criteria; however, the design cannot be finalized until after the site utilities have been installed and the streets are at approximate grade. Additional exploration and testing will be required at that time to establish the final pavement section design. The final pavement sections could vary significantly from the estimates provided based on the actual traffic counts assigned to the roadways, the actual strength coefficients of the subgrade soils and on the jurisdiction for the roadway design. Earth Engineering Consultants, Inc. EEC Project No. 1962023a March 23, 1999 1 Page 4 observations in piezometers or monitoring wells which are sealed from the influence of surface water would be required to more accurately evaluate ground water levels. Zones of perched or trapped water may be encountered at times throughout the year. Fluctuations in ground water levels and the location and amount of perched water can occur over time depending on variations in hydrologic conditions and other conditions not apparent at the time of this report. ANALYSIS AND RECOMMENDATIONS Foundations Based on the materials observed at the test boring locations, we anticipate the proposed lightly loaded residential structures could be supported on conventional footing foundations. For footing foundations supported on the near surface sandy lean clay, we anticipate foundation bearing' pressures in the range of 1,500 to 2,500 psf could be used for design. Relatively low Leval bearing pressures of 1,500 psf should be considered for footing foundations extending near the ground water table. In some areas, especially near the ground water table, it may be necessary to use overexcavation and backfill techniques to develop suitable strength materials for support sl of footing foundations. Care will be necessary in establishing the foundation bearing levels to avoid placing the structures below the site ground water table. Free water was encountered at depths ranging from approximately 11 to 12 feet at the boring locations. Below Grade Areas Perimeter drain systems will be required around all below grade areas to reduce potential for hydrostatic loads on below grade walls and/or infiltration of surface water into below grad :areas. Those perimeter drain systems should gravity flow to a sump area where the water can be removed without reverse flow into the system. Earth Engineering Consultants, Inc. EEC Project No. 1962023a March 23, 1999 Page 3. SITE AND SUBSURFACE CONDITIONS The Fossil Creek Estates will be developed south of County Road 36 and east of County Road 9 in Larimer County, Colorado. The site is located immediately north of the Fossil Creek Reservoir. The Louis Swift parcel is located on the eastern side of Fossil Creek Estates as indicated on the attached boring location diagram. Site drainage is generally to the south with difference in ground surface elevations across the site on the order of 10 feet. The property is currently used as irrigated cropland. Evidence of prior building construction was not observed on this parcel by EEC site personnel. EEC personnel were on site during drilling to evaluate the materials recovered and direct the drilling activities. Field logs prepared by those 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 engineering evaluation. Based on results of the field borings and laboratory testing, subsurface condition can be generalized as follows. Four to six inches of vegetation and/or topsoil were typically encountered at the surface at the boring locations. The topsoil/vegetation was underlain by low plasticity, sandy lean clay. The cohesive materials contained varying amounts of silt and sand and were generally stiff to very stiff. Near the groundwater table, the cohesive materials became softer. The lean clay soils extended to the bottom of the borings at depths of .10 to 15 feet below present site grades. 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. WATER LEVEL OBSERVATIONS Observations were made while drilling and after completion of the borings to detect the presence and depth to the hydrostatic ground water table. At the time of drilling, free water was encountered at depths of approximately 1l.to 12 feet below existing ground surface. Longer -term 11 EEC Project No, 1962023a Earth Engineering Consultants, Inc. March 23, 1999 Page 2 estimating angles from identifiable site references. The locations of those 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, CME 45-drill rig equipped with a hydraulic head employed in drilling and sampling operations. The boreholes were advanced using d-inch nominal diameter continuous flight augers and .samples of the subsurface materials encounter&i in the borings were obtained using split -barrel sampling techniques in general accordance with ASTM Specification D-1586. In the.split-barrel sampling procedure, a standard 2-inch O.D. split - barrel sampling spoon is driven into the ground by means of a 140-pound hammer `.Pru: t distance of 30 inches. The number of blows required to advance the split barrel sampler 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 and hardness of weathered bedrock. All samples obtained in the field were sealed and returned to the laboratory for further examination. classification and testing. Moisture content tests were, completed on each of the recovered samples. In addition, the unconfined strength of appropriate samples was .estimated using a calibrated hand penetromet:,.r. Dry density tests were completed on -selected samples. Atterberg limits and washed sieve analysis tests were completed on selected samples to evaluate the amount and plasticity of the fines in the subgrade soils. Swell/consolidation tests were performed on selected samples to establish the soil's tendency to change volume with variation in moisture content. Results of the outlined tc:.ts 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 Jle Soil Classification System is shown on the boring logs and a brief description of that classification system is included with this report. PRELIMINARY SUBSURFACE EXPLORATION LOUIS SWIFT PARCEL AT FOSSIL CREEK ESTATES LARIMER COUNTY, COLORADO EEC PROJECT NO. 1962023a March 23, 1999 IINTRODUCTION The preliminary subsurface exploration for the proposed development of the Louis Swift parcel at Fossil Creek Estates located east of Larimer County Road 9 and south of Larimer County Road 36 in Larimer County, Colorado has been completed. Four soil borings extending to depths of approximately 15_feet below present ground surface were advanced in the proposed development area to evaluate existing subsurface conditions with regard to support of lightly loaded foundations, floor -slabs and pavements. Individual boring logs and a diagram indicating the approximate boring locations are included with this report: We understand this project involves the development of approximately 55 acres as a part of the Fossil Creek Estates development. The Swift portion of the Fossil Creek Estates development will include single-family residential structures. The structures expected include lightly loaded one and two-story buildings with full basements. We anticipate foundation loads for those structures would be light, less than 2.5 kips per lineal foot for continuous wall loads and less than 30 kips for individual column loads. We expect the gradechanges to develop final site grades on the property would be less than 2 to 3 feet. The purpose of this report is to describe the subsurface conditions encountered in the borings.. analyze and evaluate the test data and provide preliminary geotechnical recommendations concerning design and construction of foundations and support of floor slabs and pavements. EXPLORATION AND TESTING PROCEDURES The boring locations were selected and established in the field by representatives of Earth Engineering Consultants, Inc. (EEC). The field locations were established by pacing and March 23, 1999 EARTH ENGINEERING CONSULTANTS, INC. Everitt Companies 3030 South College Avenue Fort Collins, Colorado-80525 Attn: Mr. Stan Everitt Re: Preliminary Subsurface Exploration Louis Swift Parcel at Fossil Creek Estates Larimer County, Colorado EEC Project No. 1962023a Mr. Everitt: Enclosed, herewith, are the results of the preliminary subsurface exploration completed by Earth Engineering Consultants (EEC) personnel for the referenced project. In summary, the soils observed in the test borings completed on this site consisted of low plasticity lean clay with varying amounts of silt andsand. Groundwater was observed at a depth of approximately 11 to 12 feet site grades. Based on the materials observed at the test.boring locations, it is our opinion !ia: materials could be used for direct support of lightly loaded residential structures using conventional footing foundations. The near surface low plasticity cohesive soils could also be used for direct support of floor slabs and pavements. Preliminary geotechnical recommendations concerning design and construction of foundations and support of floor slabs and pavements are presented in the !e a of the attached report. 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 Engj>,�geCng Consultants, Inc. [f LLL/dmf CENTRE FOR ADVANCED TECHNOLOGY 2301 RESEARCH BOULEVARD, SUITE 1 04 FORT COLLINS, COLORADO 80526 (970) 224-1522 (FAX) 224-4564 PRELIMINARY SUBSURFACE EXPLORATION LOUIS SWIFT PARCEL AT FOSSIL EREEK ESTATES LARIMER COUNTY, COLORADO EEC PROJECT NO. 1962023a