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Home My WebLink AboutSubsoil Study and Foundation Designrcrf ffiiffiffini'iiå*"' An Employcc Orncd ComPony 5020 County Road 154 Glenwood Springs, CO 81601 phone: (970)945-7988 fax: (970) 945-8454 email: kaglenwood@kumarusa.com www.kumarusa.com Office t¡cations: Denver (HQ), Parker, Colorado Springs, Fort Collins, Glenwood Springs, and SuÍunit Courity, Colorado SUBSOIL STUDY FOR FOUNDATION DESIGN PROPOSED RESIDENCE LOT 4, ASGARD SUBDIVISION FOURTH FILING COUNTY ROAD 266 GARFIELD COUNTY, COLORADO PROJECT NO.2l-7A12 APRIL l3,202l PREPARED FOR: AI{DREW EAKER 3925 APPLEWOOD STREET GRAND JUCTION, COLORADO 81506 andrewse@live.com TABLE OF CONTENTS PURPOSE AND SCOPE OF STUDY ...... PROPOSED CONSTRUCTION SITE CONDITIONS........ FIELD EXPLORATION SUBSURFACE CONDITIONS FOUNDATION BEARING CONDITIONS DESIGN RECOMMENDATIONS FOUNDATIONS FLOOR SLABS SURFACE DRAINAGE..... LIMITATIONS.........,....... FIGURE 1 - LOCATION OF EXPLORATORY BORING FIGURE 2.LOG OF EXPLORATORY BORING FIGURE 3 - SV/ELL-CONSOLIDATION TEST RESULTS FIGURE 4 - GRADATION TEST RESULTS TABLE 1- SUMMARY OF LABORATORY TEST RESULTS I I I I -2- _) - 3 3 J 4 -4- Kumal & Associates, lnc. o Projecl No.21-7-212 PURPOSE AND SCOPE OF STUDY This report presents the results of a subsoil study for a proposed resídence to be located on Lot 4, Asgard Subdivision Fourth Fíling, County Road 266, Garfield County, Colorado. The project site is shown on Figure 1. The purpose of the study was to develop recommendations for the foundation design. The study was conducted in as part of our agreement for geotechnical engineering services to Andrew Eaker dated February 17,2021, An exploratory boring was drilled to obtain information on the general subsurface conditions. Samples of the subsoils obtained during the field exploration were tested in the laboratory to determine their classification, compressibility or swell and other engineering characteristics. The results of the field exploration and laboratory testing were analyzedÍo develop recommendations for foundation types, depths and allowable pressures for the proposed building foundation. This report summarizes the data obtained during this study and presents our conclusions, design recommendations and other geotechnical engineering considerations based on the proposed construction and the subsurface conditions encountered. PROPOSED CONSTRUCTION The residence will be a single story wood frame structure with attached gange located on the lot as shown on Figure 1. Ground floors will be structural over crawlspace in the living area and slab-on-grade in the garage area. Grading for the structure is expected to be relatively minor with cut depths between about 2to 4 feet. We assume relatively light foundation loadings, typical of the proposed type of construction. If building loadings, location or grading plans change significantly from those described above, we should be notified to re-evaluate the recommendations contained in this report. SITE CONDITIONS The site was a vacant field at the time of our exploration. The ground surface, which appears mostly natural, is strongly sloping down to the southeast at a grade of about 4 to 6 percent. Vegetation consists of grass. There af,e no other nearby residences. FIELD EXPLORATION The fïeld exploration for the project was conducted on March l0,202L One exploratory boring was drilled at the location shown on Figure 1 to evaluate the subsurface conditions. The boring Kumar & Associates, lnc. @ Projec't No.21-7-212 -2- was advanced with 4 inch diameter continuous flight augers powered by a truck-mounted CME- 458 drill rig. The boring was logged by a representative of Kumar & Associates. Samples of the subsoils were taken withl% inch and 2 inch I.D. spoon samplers. The samplers were driven into the subsoils at various depths with blows from a 140 pound hammer falling 30 inches. This test is similar to the standard penetration test described by ASTM Method D-l586. The penetration resistance values are an indication of the relative density or consistency of the subsoils. Depths at which the samples were taken and the penetration resistance values are shown on the Log of Exploratory Boring, Figure 2. The samples were returned to our laboratory for review by the project engineer and testing. SUBSURT'ACE CONDITIONS A graphic log of the subsurface conditions encountered at the site is shown on Figure 2. The subsoils encountered, below about %foot of topsoil, consist of very stiff, sandy siþ clay underlain at a depth of about 3 feet by medium dense, clayey gravel and sand with cobbles to the depth drilled of 26 feet. Laboratory testing performed on samples obtained from the boring included natural moisture content and density, and gradation analyses. Results of swell-consolidation testing performed on relatively undisturbed drive sample of the clayey gravel and sand soils, presented on Figure 3, indicate low compressibility under conditions of loading and wetting, and aminor expansion potential when wetted under a constant 1,000 psf surcharge. Results of gradation analyses performed on small diameter drive samples (minus l%-inchfraction) of the clayey gravel and sand subsoils a¡e shown on Figure 4. The laboratory testing is summarized in Table 1. No groundwater was encountered in the boring atthe time of drilling and the subsoils were slightly moist to moist. FOIJNDATION BEARING CONDITIONS The near surface silty clay soils encountered in the boring possess a low bearing capacity and an assumed moderate settlement potential, especially when wetted. The clayey gravel and sand soils possess moderate bearing capacity and relatively low settlement potential. Spread footings bearing on the clayey gravel and sand soils can be used for foundation support of the residence. We believe the minor swell potential exhibited in the tested sample can be neglected in foundation design but should be further evaluated at the time of excavation. Kumar & Associates, lnc. o Projec{ No.21-7-2'12 -3- DESIGN RECOMMENDATIONS FOTINDATIONS Considering the subsurface conditions encountered in the exploratory boring and the nature of the proposed construction, we recommend the building be founded with spread footings bearing entirely on the clayey gravel and sand (natural granular) soils. The design and construction criteria presented below should be observed for a spread footing foundation system. 1) Footings placed on the undisturbed natural granular soils should be designed for an allowable bearing pressure of 2,000 psf. Based on experience, we expect settlement of footings designed and constructed as discussed in this section will be about I inch or less. 2) The footings should have a minimum width of 18 inches for continuous walls and 2 feetfor isolated pads. 3) Exterior footings and footings beneath unheated areas should be provided with adequate soil cover above their bearing elevation for frost protection. Placement of foundations at least 36 inches below exterior grade is typically used in this arca, 4) Continuous foundation walls should be well reinforced top and bottom to span local anomalies such as by assuming an unsupported length of at least 12 feet. Foundation walls acting as retaining structures should also be designed to resist a IateruI earth pressure coffesponding to an equivalent fluid unit weight of at least 50 pcf. 5) Topsoil and any loose disturbed soils should be removed and the footing bearing level extended down to the relatively dense natural granular soils. The exposed soils in footing area should then be moistened and compacted. 6) A representative of the geotechnical engineer should observe all footing excavations prior to concrete placement to evaluate bearing conditions. FLOOR SLABS The natural on-site soils, exclusive of topsoil, are suitable to support lightly loaded slab-on-grade construction. To reduce the effects of some differential movement, floor slabs should be separated from all bearing walls and columns with expansion joints which allow unrestrained vertical movement. Floor slab control joints should be used to reduce damage due to shrinkage cracking. The requirements for joint spacing and slab reinforcement should be established by the Kumar & Associates, Inc. 6 Project No.21-7-212 -4- designer based on experience and the intended slab use. A minimum 4 inch layer of well graded sand and gravel base course should be placed immediately beneath the garage slab for support and to facilitate drainage. This material should consist of minus Z-inchaggregate with at least 50Yorctained on the No. 4 sieve and less than l2Yopassingthe No. 200 sieve. All fill materials for support of floor slabs should be compacted to at least 95Vo of maximum standard Proctor density at a moisture content near optimum. Required fill can consist of the on- site soils devoid of vegetation, topsoil and oversized þlus 6-inch) rocks. SURFACE DRAINAGE A perimeter drain around shallow crawlspace areas (less than4 feet deep) should not be needed with adequate compaction of foundation backfill and positive surface drainage away from foundation walls. The following drainage precautions should be observed during construction and maintained at all times after the residence has been completed: 1) Inundation ofthe foundation excavations and underslab areas should be avoided during construction. 2) Exterior backfill should be adjusted to near optimum moisture and compacted to at least 95Yo of the maximum standard Proctor density in pavement and slab areas and to at least 90Yo of the maximum standard Proctor density in landscape areas. 3) The ground surface surrounding the exterior of the building should be sloped to drain away from the foundation in all dírections. We recommend a minimum slope of 12 inches in the first 10 feet in unpaved areas and a minimum slope of 3 inches in the first l0 feet in paved areas. 4) Roof downspouts and drains should discharge well beyond the limits of all backfìll. 5) Landscaping which requires regular heavy irrigation, such as sod, and lawn sprinkler heads should be located at least l0 feet from foundation walls. LIMITATIONS This study has been conducted in accordance with generally accepted geotechnical engineering principles and practices in this arcaatthis time. V/e make no warranty either express or implied. The conclusions and recommendations submitted in this report are based upon the data obtained from the exploratory boring drilled at the location indicated on Figure 1, the proposed type of construction and our experience in the area. Our services do not include determining the presence, prevention or possibility of mold or other biological contaminants (MOBC) developing Kumar & Associates, lnc. ô Project No.21-7-212 5 in the future. If the client is concerned about MOBC, then a professional in this special field of practice should be consulted, Our ñndings include extrapolation of the subsurface conditions identified at the exploratory boring and variations in the subsurface eonditions may not become evident until excavation is performed. If conditions encountered during consfruction appear different from those described in this reporto we should be notified so that re-evaluation of the reeommendations may be made. This report has been prepared for the exclusive use by our client for design pu{poses. We are not responsible for technical interpretations by others of our information. As the project evolves, we should provide continueS consultation and field services during construction to review and monitor the implementation of our recommendations, and to veriff that the recommendations have been appropriately interpreted. Signiñcant design changes may require additional analysis or modifications to the reeommendations presented herein. We recommend on-site observation of excavations and foundation bearing strata and testing of structural fill by a representative of the geotechnical engineer. Respectfully Submitted, Kumar & Associates, Inc. James H. Parsons, P.E. Reviewedby: David A. Young, P. JHP/kac cc: JeffJohnson Johnson (þffi4iþchit-qctural. qqn ) Kumar & Associates, lnc. 6 Project No.21-7-212 BORING 1 EL.=5925'LEGEND N T0PSOlL¡ CltY ANÐ SILT, ORGANIC, FIRM, lI0lSI, DARK BROWil. 21/12 CLAY (CL); SILTY, SANDY, VERY STIFF, STJGHTLY MOISÍ, TAN. 15/12 WC=9.5 5 DD=1 15 25/6, 5o/5 WC=6.1 DD=120 +,1=,[6 -200=19 ffi GRAVEL AND SAND SUGHTLY MOISÏ TO (cc); cogsus, CLAYEY, ilEDlult DENSE, notsf, IflxED 8R0wN. l-.l¡l Lrll& I:cF-o-l¡¡ff F I DRIVE SA}TPU, 2-INCI{ I.D. CAUFORNIA UilER SAMPL"E. 10 51/12 DRIVE SAttPLt, I 3/8-|NCH l.D. SPUT Sp00N STANDARD PENETRATION TEST. ¡rrraDRlVE SAMPLE BLOW C0UNT. INDICATES THAT 2l BLOWS 0F¿tI tL ^ r/m-pouND HAlntER FAlrJNc J0 rNcHEs wERE REQUTRED TO DRIVE THE SAIIPTTR 12 INCHES. 15 ts/12 WC=8.5 NOTEg 1. THT TXPLORATORY BORING TVAS DRII,I.TD ON ITARCH 10, 2O2I WTH A 4-INCH DIAIIEÍER CONTINUOUS FLIGI{T POYÍIR AUGER. 20 26/12 2. THT LOCATION OF THE EXPLORATORY BORING IYAS MEASURED APPROXIIIATTLY BY PACING FRO¡I FEATURES SHOWN ON THE SITE PLAX PROVIDED. 3. TI{E TI,TVATION OF THE EXPTORATORY BORING WAS OBTAINED BY INTERPOUTION BNWEEN CONTOURS ON TI{E SITE PUN PROVIDED. 25 1. THI TXPLORATORY BORING LOCATION AND EI.TVATION SHOUID 8E CONSIDERTD ACCURATT ONLY TO TI{E DEGRTE IMPUTD BY THE ¡ITTHOD USTD. 58/12 5. THE UNES BENVEEN IIATIRIAIS SHOWI{ ON THË TXPLORATORY BORINC LOG REPRESTNT THE APPROXIMATT BOUNDARIES BEÍWEEN MATERIAT TYPES AND THT TRANS¡TIONS TIAY BI GRADUAL 20 6. GROUNDWATER WAS NOT ENCOUNTERED IN THT BORING AT THE TITIE OF DRILLING. 7. LABORATORY TEST RESULTS: WC = ìYATER COI{TENT (X) (ASTIT D 2216); DD = DRY DENSITY (pcf) (ASTM D 22f6); +¿l = PTRCENTAGE RnAlNtD 0N N0. 4 SIEVE (rsru o ogrs)¡ -200 = PERCEI{TAGE PASSING N0. 200 SIEVE (ASTH 0 ilao); 21-7-212 Kumar & Associates LOG OF EXPLORATORY BORING Fig. 2 SAMPLE OF: Cloyey Grovcl ond Sond FROM:BorlnglO4' WC = 9.5 X, DD = 115 pcf l EXPANSION UNDER CONSTANT PRESSURE UPON WETTING :l: :: 1 i I .-i=- _'..__'-'- -_: -l ^0¡( J.J -lt¡l =1n ._2 zoË o Jo anzo()_4 21-7-212 Kumar & Associates SWELL-CONSOLIDATION TEST RESULT Fig. 3 ¡ E å ¡ TTYDROXETER ANALYSIS SIEYE ANALI1SIS ñaÊ tclol¡os ! I ! i I i i I I I 1 I _t l I t / I l -. t- I SAND GRAVEL 2 FINE MEOlUM COARSE FINE COARSE I F o to þ tlt & !t¡ ao 70 to 90 too t T F .ol .o¡17 .500 .too CITY TO SILI COBBLES GRAVEL 16 '( SANO UQUID UMIÎ SAIIPLE OF: Cloycy Grovcl ond Sond 5tt ,( PI.ASTICITY INDEX srLT ANO Ct¡Y 19 X FROII: Eorlng I 07' ! E o lo m to ,aO lo ao ?o to ¡o too Ê F DIAMETER OF IN CIáY TO SILT COBBLES GRAVEL ß X SAND UOUID UMIT SAYPIE OF¡ Cloycy Grovcl qnd Sond 5JX PLASTIC|TY INDEX SILT AND CI¡Y 19 Z FROII:BorlnglOlS' ths U ruulh ôÞply onlt lo tù.æmplü rhloh u.ð Lri.d. Th.ll.llng nÞorl rholl not b. nÞrcduo.d,ü6pt ln full. rllhô¡¡l tlì. udllmoppml of l(umqr & A[oolol.|, lnc.Slm onoltrlr l.¡llng b p.rtom.d lnoodom rllh AStli D6elt. AsÎr¡ D7928. ASlL ClS6 ond/or ^SlU Dll¡l{r. HYDROI¡EIER ANALYSIS SIEVE AI{ALYSIS ta t{t¡t H¡3 U.s. STA¡{DAND IEIES tL. I / I ! I f i i I -i' '¡ j j l ¡ I ¡ I I r I SAND GRAVEL FINE MEDIUM FINE COARSE 21 -7 -21 2 Kumar & Associates GRADATION TEST RESULTS Fig. 4 lcrtI¡rna&Ascocffi,lnc.@Geotedrnical and Materials Engineersard Environmental ScientisßTABLE 1SUMMARY OF LABORATORY TEST RESULTSNo.21-7.2121BORING1574{fnDEPTHSAIIIPLE LOCATION8.36.19.5f%ìNAÏURAtTOISTURECONTENT120ll5NATURALDRYDENSITYGRADATIONGRAVEL(%)SA¡¡Df,6)4846JJ35t9r9PERCENTPASSI¡|G NO,200stwEATTERBERG LITIITSLIQUID LIISITPLASTICINDÞ({osflUT{CONFINEDcoÌlPREsst\ÆSTRENGTHClayey Gravel and SandClayey Gravel and SandClayey Gravel and SandSOL TYPE