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Home My WebLink AboutSubsoil Study for Foundation Design 07.11.17H-PryKUMAR Geotechnical Engineering I Engineering Geology Materials Testing I Envlronmentral 5020 County Road 154 Glenwood Springs, CO 81601 Phone: (970) 945-7988 Fax (970) 945-8454 Email: hpkglenwood@kumarusa.c,om Office Locations: Parker, Glenwood Springs, and Silverthorne, Colorado ST]BSOIL STUDY FOR FOUNDATION DESIGN PROPOSED RESIDENCE LOT 5, BLOCK 1 THE RESERVE AT BATTLEMENT MESA OOOS MEADOW CREEK DRWE GARFIELD COUNTY, COLORADO PROJECT NO. 17-7460 JULY Ll,20l7 PREPARED FOR: AMY AND CHUCK PERRIN 38 PINETREE PLACE PARACHUTE, COLORADO 81635 (am)¡leeperrin @ gmail.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 UNDERDRAIN SYSTEM SURFACE DRAINAGE .., LIMITATIONS FIGURE 1 - LOCATION OF EXPLORATORY BORING FIGURE 2 -LOG OF EXPLORATORY BORING FIGURES 3 and 4 - SWELL-CONSOLIDATION TEST RESULTS TABLE 1- SUMMARY OF LABORATORY TEST RESULTS _1_ I ..-2- 2- 3- ...- 6 - H.P*KUMAR Project No. 17-7-460 PURPOSE AND SCOPE OF STUDY This report presents the results of a subsoil study for a proposed residence to be located on Lot 5, Block l, The Reserve at Battlement Mesa, 0008 Meadow Creek Drive, 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 accordance with our agreement for professional services to Amy and Chuck Perrin dated June 8,2017 . An exploratory boring was drilled to obtain information on the subsurface conditions. Samples of the subsoils obtained during the field exploration were tested in the laboratory to determine their classification, cornpressibility or swell and other engineering characteristics. The results of the field exploration and laboratory testing were analyzed to develop recommendations for foundation t¡,pes, 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 proposed residence will be lVz story wood frame construction above a crawlspace with an attached garâge. The garage floor will be slab-on-grade. Grading for the structure is assumed to be relatively minor with cut depths between about 3 to 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 lot is vacant and vegetated with grass and weeds. The ground surface is slightly to moderately sloping down to the southeast. Golf course borders the west and south rear part of the property. A pond is located on the golf course about 250 feet south of the lot. H-P\KUMAR Project No. 17-7-460 -2- FIELD EXPLORATION The field exploration for the project was conducted on June 9, 2017. One exploratory boring was drilled at the location shown on Figure I to evaluate the general subsurface conditions. The boring 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 H-p/Kumar. Samples of the subsoils were taken with 1% 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-1586. 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. SUBSURFACE CONDITIONS A graphic log of the subsurface conditions encountered at the site is shown on Figure 2. The subsoils encountered, below minor vegetation and topsoil, consisted of about 32 feetof stiff to very stiff, sand and silt that was clayey with depth and underlain by relatively dense, clayey sandy basalt gravel with cobbles and boulders that extended down to the boring depth of 34 feet. Drilling in the dense granular soils with auger equipment was difficult due to the cobbles and boulders. Laboratory testing performed on samples obtained from the borings included naturat moisture content and density, and percent finer than sand size gradation analyses. Results of swell- consolidation testing perfornred on relatively undisturbed drive samples of the sand and silt soil, presented on Figures 3 and 4, indicate low to moderate compressibility under conditions of loading and wetting, with a nil to low hydro-compression potential. The laboratory testing is summarized in Table l. H-P\KUMAR Project No. 17-7-460 3 No free water was encountered in the boring at the time of drilling and the subsoils were slightly moist. FOUNDATION BEARING CONDITIONS Based on our experience in the area, the fine grained sand and silt soils at the site will typically tend to settle when wetted even under light loadings conditions. Spread footings bearing on the natural soils can be used for foundation support of the residence with a risk of settlement and building distress. The risk of settlement is primarily if the bearing soils were to become wetted and care should be taken in the surface and drainage around the house to prevent the soils from becoming wet. It will be critical to the long term performance of the sructure that the recommendations for surface drainage contained in this repûrt be followed. A lower risk foundation alternative could be achieved by removal of a depth (typically 3 feet) of the soils below the spread footings and replacing in a moistened and well compacted condition, or by extending the foundation bearing down to the dense coarse granular soils such as by helical piers or screw piles. Provided below are recommendations for spread footings bearing on the natural soils. If rccommendations for structural fill below the footings or for a helical pier or screw pile foundation are desired, we should be contacted. DESIGN RECOMMENDATIONS FOUNDATIONS Considering the subsurface conditions encountered in the exploratory boring and the nature of the proposed construction, we believe the building can be founded with spread footings bearing on the natural soils with a risk of settlement. Precautions should be taken to prevent wetting of the bearing soils. The design and construction criteria presented below should be observed for a spread footing foundation system. H-P\KUMAR Project No. 17-7-460 1) 4 Footings placed on the undisturbed natural soils should be designed for an allowable bearing pressure of 1,000 psf. Based on experience, we expect settlement of footings designed and constructed as discussed in this section will be about 1 inch or less. The could be some additional settlement if the bearing soils were to become wetted. The magnitude of the additional settlement would depend on the depth and extent of the wetting but may be on the order of I ta lr/z inches. The footings should have a minimum width of 18 inches for continuous walls and 2 feet for isolated pads. 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 typicatly used in rhis area. Continuous foundation walls should be heavily reinforced top and bottom to span local anomalies and better withstand the effects of some differential settlement such as by assuming an unsupported length of at least 14 feet, Foundation walls acting as retaining structures should also be designed to resist a lateral earth pressure coffesponding to an equivalent fluid unit weight of at least 50 pcf. All existing fill, topsoil and any loose or disturbed soils should be removed and the footing bearing level extended down to the undisturbed firm natural soils. The exposed soils in footing area should then be moistened and well compacted. A representative of the geotechnical engineer should observe all footing excavations prior to concrete placement to evaluate bearing conditions. 2) 3) 4) s) 6) FLOOR SLABS The natural on-site soils, exclusive of topsoil, are suitable to support lightly loaded slab-on-grade construction with the risk of settlement if the subgrade were to become wetted as discussed above. To ¡educe 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 skinkage cracking. H-PIKUMAR Project No. 17-7-460 -5- The requirements for joint spacing and slab reinforcement should be established by the designer based on experience and the intended slab use. A minimum 4 inch layer of well graded sand and gravel, such as road base, should be placed beneath the garage slab for support and to facilitate drainage. This material should consist of minus 2 inch aggregate with af Ieast 50Va retained on the No. 4 sieve and less than !2Vo passing the No. 200 sieve. All fill materials for support of floor slabs should be compacted to at least 957o of maximum standard Proctor density at a moisture content near optimum. Required fill can consist of the on- site soils devoid of vegetation and topsoil. UNDERDRAIN SYSTEM Although free water was not encountercd during our exploration, it has been our experience in the area that local perched groundwater can develop during times of heavy precipitation or seasonal runoff. Frozen ground during spring runoff ean also create a perched condition. We recommend below-grade construction, such as retaining walls and basement areas, be protected from wetting and hydrostatic pressure buildup by an underdrain system. A perimeter foundation drain a¡ound shallow (less than 4 feet deep) crawlspace areas should not be needed with adequate compaction of foundation backfill and positive surface slope grade away from fot¡ndation walls. The drain (if placed) should consist of drainpipe placed in the bottom of the wall backfill surrounded above the invert level with free-draining granular material. The drain should be placed al each level of excavation and at least 1 foot below lowest adjacent finish grade and sloped at a minimu m l7o to a suitable gravity outlet or to a sump and pump system. Free- draining granular material used in the underdrain system should contain less than 27o passing the No. 200 sieve, less than 507o passing the No. 4 sieve and have a maximum size of 2 inches. The drain gravel backfill should be at least lVz feet deep and be covered by filter fabric such as Mirafi 140N. H.P\KUMAR Project No. 17-7-460 -6- SURFACE DRAINAGE Positive surface drainage is a very important aspect of the project to prevent wetting of the bearing soils. The following drainage precautions should be observed during construction and maintained at ali times after the residence has been completed: 1) lnundation 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 95Vo af the maximum standard Proctor density in pavement and slab areas and to at least 9AVo af 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 directions. Vy'e recommend a minimum siope of 12 inches in the first 10 feet in unpaved areas and a minimum slope of 3 inches in the first i0 feet in paved areas. 4) Roof downspouts and drains should discharge well beyond the limits of all backfill. 5) Landscaping which requires regular heavy inigation should be located at least l0 feet from foundation walls. Consideration should be given to use of xeriscape to reduce the potential for wetting of soils below the building caused by irigation. LIMITATIONS This study has been conducted in accordance with generally accepted geotechnical engineering principles and practices in this area at this time. lVe make no warranty either express or implied. The conclusions and recommendations submitted in this report are based upon the dara 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 dctcrmining the presencs, prevention or possibility of rrold or other biological conrâminants (MOBC) developing in the future. If the client is concerned about MOBC, then a professional in this special field of practice should be consulted. Our findings include extrapolation of the subsurface conditions identified at the exploratory boring and variations in the subsurface conditions may not become H-P\KUMAR Project No. 17-7-460 -7 - evident until excavation is performed. If conditions encountered during construction appear different from those described in this report, we should be notifred so that re-evaluation of the recommendations may be made. This report has been prepared for the exclusive use by our client for design purposes. We are not responsible for technical interpretations by others of our information. As the project evolves, we should provide continued consultation and field services during construction to review and monitor the implementation of our rccommendations, and to verify that the recommendations have been appropriately interpreted. Significant design changes may require additional analysis or modifications to the recommendations 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, H-P\ KU Louis E. Eller Reviewed by: David A. Young, P.E. LEE/ksw cc: RC Construction - R (lori.cartwright @ wellmaster.com) All Draft Design- Gilbert Maynard (gilbertmaynard@ email.com) 32-g.1tt H.P*KUIVIAR Project No. 17-7-460 MEADOW CREEK DRIVE LOT 4 \ I \ I LOT 6 I I Þ.$0 APPROXIMATT SCALE-FEET OO8 MEADOW CREEK DRIVE a BORING 1 LOT 5 17 -7 -460 H-PryKUMAR LOCATION OF TXPLORATORY BORING Fig. 1 BORING 1 LEGEND 0 sANÐ ÄND SILT (SM-l,rt); CLAYTY W|TH 0EPTH, STTFF I0 VtRy STtfF W H DIPTH, SLIGHTLY MOIST, LIGHT BROWN. 12112 WC=?.0 DD=99 -200=54 FA V)l,/'l GRÂvtL (Cc); BASALT C0BBLES ÀN0 B0ULDIRS, cLAYtY, SÅNDY, ÐtNst, sltcllllY MotsT, BR0WN. q 1a/n WC=2.7 DD=98 F I ORIVE SAMPLT, 2_INCH I.D, CALIFORNIA LINTR SAMPL'. 20/12 ÐRrvE SAMPLË, 1 3/E-|NCH LD. SPUT Sp00N STANoÀRD ptNtTRATtoN TTST, 10 16112 WC=3.4 0D=1 06 11712 DRIVE SAMPLT BLOW C0UNT, INDICATES THAT 23 BLOWS 0F.", .. 14o-POUND HAMMER FALLING 30 INCHIS WERT REQUIRTD THE SAMPLIR 12 INCHTS. A IO DRIVT N9TES 4Ê 23/ t2 THI TXPLORAIORY SORING WAS ORILLED ON JUNI 9,2017 WIÍH A 4-INCH OIAMITTR CONT]NUOUS FLIGHT POWER AUGER.t-t¡l LÀJtr- Iï¡- lrJ 2, THI LOCATION OF THT TXPLORAIORY BORING WAS MTASURED ÁPPROXIMAÏELY 8Y PACING FROM FIATURTS SHOWN ON THE SITE PLAN PROVIDID, 20 36/12 WC=3.5 D0= l 05 3. THT TLTVATION OF THT TXPLORATORY BORING WÂS NOT MTASURED AND THE LOG OF THE TXPLORAÏORY BORING IS PLOTTTD TO DTPTH 4. THE TXPLORAÏORY BORING LOCATION AND ELIVATION SHOULD 8I CONSIDTREO ACCURATT ONLY TO THE DECRIE IMPLITD BY THT MTTHOD USTD. t¡i 83/12 5. IHE LINTS BTTWTTN MATTRIAL5 SHOWN ON THT IXPLORATORY SORING LOE RIPRESTNT THT ÂPPROXIMATT BOUNDARITS BTIWTIN MÅTTRIAL TYPIS ÀND ll[ TRÂNSITIO¡IS MAY 9T GRAOUAL, 6, GROUNDWAITR WAS NOT TNCOUNTÊRTÐ IN THE BORING AI THT IIMI OF ORILLINO. zn 7. LABORATORY TTST RTSULTS: WC = WÀTIR C0NTINT (%) (ÂsTM Ð 2?16); 00 = oRy DtNsrTy (pcf) (¡stu 0 zzr0)l -200 = PËRCINÍAGI PASSING N0. 200 SltV[ (ÅSTM D 1 1 40). 44/6,4a/2 1C 17 -7 -464 H.PryKUMAR LOG OF TXPLORATORY BORING Fig. 2 I SAMPLE OF: Sond ond Silt FROM;Boringl@5' \NC = 2.7 %, Dù = 98 pcf I ADDITIONAL COMPRESSION UNDER CONSTANT PRESSURE DUE TO WETT¡NG JJ l¡J =v) I zo '-o =olnzoo 1 0 1 -t -^ 1.0 APPLIED PRÊSSURÊ - KSF 1O r00 JJ Ld =a I zo F o Jotnzo() ,l 0 1 2 -3 -4 APPLIED PRËSSURE - KSF I 100 SAMPLE OF: Cloyey Sond ond Sili FROM: Boring 1 @ 10' WC : 3.4 %, OD = 106 pcf nt!. 1!!t ,lrulb !!ply ont 1o ü!lorylB 1.!td. ftG t.lling .cpod lhûll ñol b. !êpducd,.xc!Þt ¡ir{ìi, r¡ltuul lh. rrih.n cpÞrml otKum. ı¡d &sriolcs, lnc. Sr!¡lgoMlidotioñ l..lirq Fdorñôd i¡ .sco¡do¡r. rith ñ D-a545. ADDITIONAL COMPRESSION UNDER CONSTANT PRESSURË DUT TO WETIING 17 -7 - 460 H-PryKUMAR SWELL_CONSOLIDATION TEST RESULTS Fig. 3 SAMPLE OF: Cloyey Sondy Silt FROM:Boringle^2A' WC = 3,5 %, DA = 105 pcf t I T lutl. D-t5t6 l a t I I I I ¡ ! , I I 1 1 i l I : I : : I : . I I 1 I : I i i 1 t : : ADDITIONAL COMPRISSION UNÐER CONSTÀNT PRESSURE DUE TO WETTING I t 1 J) a¡l =U) 0 -1 -2zo t- o Jo U1zo(J -3 -4 10 r00 17 -7 - 460 H-PryKUMAR SWELL-CONSOLIDATION TEST RTSULTS Fig.4 H-P\KUMARTABLE 1SUMMARY OF LABORATORY TEST RESULTSProject No. 1 7-7-460SOILTYPESand and SiltSand and SiltClayey Sand and SiltClayey Sand and SiltUNCONFINEDCOHPRESSIVESTRENGTHIPSFìATTERBERG LIMITSPLASTICINDEX(o/olLIQUIDLIMIT(o/ol54PÊRCENTPASSINGNO.200SIEVESAND(vùGRAVEL%tNATURALDRYDENSITYlocfl9998106105NATURALMOISTURECONTENT(o/ol2.O2.73.43_5DEPTHtfrl2r/z5I020BORINGI Dave Arqo From: Sent: To: Subject: Dana Peterson Friday, September 08,20L7 2:47 PM Jenny Langhorst Wellness Stipend! Congratulations! You have earned your 2077 wellness stipend in the full amount of 5100. And you'll be entered to win the Smart Wotch! The drawing will happen next week. Stay tuned ! This S1OO will be included on your paycheck for the September 22nd payroll. Please contact me if you have any questions at all and thank you so much for part¡cipating in the 2017 Garfield County Wellness Program! ln Health, Dana Dana L. Peterson, SPHR, SHRM-SCP Senior Benefits Administrator Garfield County Human Resources 201 Bth Street Glenwood Springs, CO 81601 Direct: 970-384-3822 Fax: 970-384-5009 Email:@ CONFIDENTIALITY NOTE: This email and any files transmitted w¡th ¡t are intended only for the person or ent¡ty to which it is addressed. lf you have received this email in error, please immediately not¡fy the sender by email and delete it from your files, 1