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Home My WebLink AboutSoils Report 07.02.2018H.PryKUMAR 5020 County Road 154 Glenwood Springs, CO 81601 Phone: (970) 945-7988 Farc (970) 945-8454 Email : hpkglenwood@kumarusa.com Office Locations: Denver (HQ), Parker, Colorado Springs, Fort Collins, Glenwood Springs, Summit County, Colorado SUBSOIL STUDY FOR FOUNDATION DESIGN PROPOSED GOS CHA/LEFAVE RESIDENCE LOT 26,FILING 4, OAK MEADOWS OOOS HAYSTACK ROAD GARFIELD COUNTY, COLORADO PROJECT NO. 18-7-37s JULY 2,2018 PREPARED FOR: McK COMPANY, INC. ATTN: EARL MCKERRIHAN 1T SOUTH PAINTED HORSE CIRCLE NEW CASTLE, COLORADO 81647 earl@mckcompan)'.net Geotechnical Engineering I Engineering Geology Materials Testing I Environmental TABLE OF CONTENTS PURPOSE AND SCOPE OF STUDY . PROPOSED CONSTRUCTION SITE CONDITIONS FIELD EXPLORATION SUBSURFACE CONDITIONS DESIGN RECOMMENDATIONS ................ FOUNDATIONS FOUNDATION AND RETAINING V/ALLS.. FLOOR SL48S........ UNDERDRAIN SYSTEM ........... SURFACE DRAINAGE .............. LIMITATIONS FIGURE I - LOCATION OF EXPLORATORY BORINGS FIGURE 2 - LOGS OF EXPLORATORY BORINGS FIGURE 3 - LEGEND AND NOTES FIGURES 4 and 5 - SWELL-CONSOLIDATION TEST RESULTS FIGURE 6- GRADATION TEST RESULTS TABLE 1- SUMMARY OF LABORATORY TEST RESULTS ., 3 3 4 5 6 6 I I I ...,,.- 2 - -7 - H-PÑKUMAR Project No. 18-7-375 PURPOSE AND SCOPE OF STUDY This report presents the results of a subsoil study for the proposed Goscha./Lafave residence to be located on Lot 26,Frling4, Oak Meadows, 0008 Haystack Road, Garfield County Colorado. The project site is shown on Figure l. The purpose of the study was to develop recommendations for the foundation design. The study was conducted in accordance with our agreement for geotechnical engineering services to McK Company, [nc. dated May 23,2018. A field exploration program consisting of exploratory borings was conducted 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, compressibility or swell and other engineering characteristics. The results of the field exploration and laboratory testing were analyzed to 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 proposed residence will be a one-story wood-frame structure with an attached garage located on the lot as shown on Figure l. Ground floor of the residence will be structural over crawl- space and the garage floor will be slab-on-grade. Grading for the structure is assumed to be relatively minor with cut depths between about 2 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 currently vacant and the ground surface appears mostly natural. The terrain is relatively flat with a strong slope down to the north and northeast at grades of about 5 to l7o. H.P\KUMAR Project No. 18-7-375 -2- The slope grades become moderately steep in the eastern and northern parts of the lot and on the order of 12 to 25Eo. Elevation difference across the builcling foot-print is about 3 feet and across the lot is about l5 feet. Vegetation at the site consists of native grass and weeds and scattered scrub oak. FIELD EXPLORATION The field exploration for the project was conducted on June 12, 2018. Two exploratory borings were drilled at the locations shown on Figure I to evaluate the subsurface conditions. The borings were advanced with 4 inch diameter continuous flight augers powered by a truck- mounted CME-458 drill rig. The borings were 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 14O-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 Logs of Exploratory Borings, Figure 2. The samples were returned to our laboratory for review by the project engineer and testing. SUBSURFACE CONDITIONS Graphic logs of the subsurface conditions encountered at the site are shown on Figure 2. The subsoils encountered, below about I foot of topsoil, consisted of from about lVz to 2 feet of medium dense, very clayey sand with scattered gravel overlying medium dense, clayey sand and gravel with cobbles and probable boulders that extended down to the boring depths of 16 feet. Laboratory testing performed on samples obtained from the borings included natural moisture content and density, and gradation analyses. Results of swell-consolidation testing performed on relatively undisturbed samples of the matrix material of the clayey sand and gravel soils, presented on Figures 4 through 6, indicate generally moderate compressibility under conditions of loading and wetting, with a low collapse potential when wetted under a constant light surcharge. Results of gradation analyses performed on a small diameter drive sample (minus l7z H-P\KUMAR Project No.'18-7-375 -3- inch fraction) of the sand and gravel subsoils are shown on Figure 7. The laboratory testing is summarized in Table L No free water wäs encountered in the borings at the time of drilling and the subsoils were slightly moist. DESIGN RECOMMENDATIONS FOUNDATIONS Considering the subsurface conditions encountered in the exploratory borings and the nature of the proposed construction, we recommend the building be founded with spread footings bearing on the natural sand and gravel with cobbles soils below all topsoil and very clayey sand soils, with some risk of settlement. The risk of settlement is primarily if the bearing soils were to become wetted and precautions should be taken to prevent wetting. The design and construction criteria presented below should be observed for a spread footing foundation system. 1) Footings placed on the undisturbed natural sand and gravel with cobble 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. There 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 Yz to 1 inch. 2) The footings should have a minimum width of l8 inches for continuous walls and 2 feet for 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 area. 4) Continuous foundation walls should be well reinforced top and bottom to span local anomalies and better withstand the effects of some differential settlement H.P\KUMAR Project No. 18-7-375 -4- 5) such as by assuming an unsupported length of at least 12 feet. Foundation walls acting as retaining structures should also be designecl to resist lateral earth pressures as discussed in the "Foundation and Retaining Walls" section of this report. All topsoil, very clayey sand soils and any loose disturbed soils should be removed and the footing bearing level extended down to the relatively dense natural sand and gravel with cobble soils. The exposed soils in footing area should then be moistened and compacted. A representative ofthe geotechnical engineer should observe all footing excavations prior to concrete placement to evaluate bearing conditions. FOUNDATION AND RETAINING WALLS Foundation walls and retaining structures which are laterally supported and can be expected to undergo only a slight amount of deflection should be designed for a lateral earth pressure computed on the basis of an equivalent fluid unit weight of at least 50 pcf for backfill consisting of the on-site soils. Cantilevered retaining structures which are separate from the residence and can be expected to deflect sufficiently to mobilize the full active earth pressure condition should be designed for a lateral earth pressure computed on the basis of an equivalent fluid unit weight of at least 45 pcf for backfill consisting of the on-site soils. The backfill should not contain topsoil or oversized (plus 6 inch) rocks. All foundation and retaining structures should be designed for appropriate hydrostatic and surcharge pressures such as adjacent footings, traffic, construction materials and equipment. The pressures recommended above assume drained conditions behind the walls and a horizontal backfill surface. The buildup of water behind a wall or an upward sloping backfill surface will increase the lateral pressure imposed on a foundation wall or retaining structure. An underdrain should be provided to prevent hydrostatic pressure buildup behind walls. Backfill should be placed in uniform lifts and compacted to at least 98Vo of the maximum standard Proctor density at a moisture content near optimum. Backfill in pavement and walkway areas should be compacted to at least 95Va of the maximum standard Proctor density. Care 6) H.P\KUMAR Project No. 18-7-375 5 should be taken not to overcompact the backfill or use large equipment near the wall, since this could cause excessive lateral pressure on the wall. Some settlement of deeper foundation wall backfill should be expected, even if the material is placed correctly, and could result in distress to facilities constructed on the backfill. The lateral resistance of foundation or retaining wall footings will be a combination of the sliding resistance of the footing on the foundation materials and passive earth pressure against the side of the footing. Resistance to sliding at the bottoms of the footings can be calculated based on a coefficient of friction of 0.40. Passive pressure of compacted backfill against the sides of the footings can be calculated using an equivalent fluid unit weight of 350 pcf. The coefficient of friction and passive pressure values recommended above assume ultimate soil strength. Suitable factors of safety should be included in the design to limit the strain which will occur at the ultimate strength, particularly in the case of passive resistance. Fill placed against the sides of the footings to resist lateral loads should be a well graded granular material compacted to at least 95Vo of the maximum standard Proctor density at a moisture content near optimum. FLOOR SLABS The natural on-site soils, exclusive of topsoil, are suitable to support lightly loaded slab-on-grade construction. There could be some slab settlement if the subgrade were to become wetted as discussed above under "Foundation Recommendations". 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 designer based on experience and the intended slab use. A minimum 4 inch layer of sand and gravel base course should be placed immediately beneath floor "slabs at grade" for support and to facilitate drainage, This material should consist of minus 2 inch aggregate with at leasl.5OVo retained on the No. 4 sieve and less than lTVo passing the No. 200 sieve. H-P\KUMAR Project No. 18-7-375 -6- 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 topsoil and oversized (plus 6 inch) rocks. UNDERDRAIN SYSTEM Although free water was not encountered during our exploration, it has been our experience in the area and where clayey soils are present that local perched groundwater can develop during times of heavy precipitation or seasonal runoff. Frozen ground during spring runoff can also create a perched condition. We recommend below-grade construction, such as retaining walls, crawlspace and basement areas, be protected from wetting and hydrostatic pressure buildup by an underdrain system. The drains 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 at each level of excavation and at least I foot below lowest adjacent finish grade and sloped at a minimum l%o to a suitable gravity outlet. Free-draining granr.rlar material used in the underdrain system should contain less than 2Vo 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 lVzfeet deep and be covered by filter fabric such as Mirafi 140N. SURFACE DRAINAGE Positive surface drainage is an important aspect of the project to prevent wetting of the bearing soils below the residence. 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 acljusted to near optimum moisture and compacted to at least 95Vo of the maximum standard Proctor density in pavement and slab areas and to at least 907o of the maximum standard Proctor density in landscape areas. H-P\KUMAR Project No. 18-7-375 7- 3)The ground surface surrounding the exterior of the building should be sloped to drain away from the foundation in all directions. we recommend a minimum slope of 12 inches in the fìrst 10 feet in unpaved areas ancl a minimum slope of 3 inches in the first l0 feet in paved areas. Roof downspouts and drains should discharge well beyond the limits of all backfill. Landscaping which requires regular heavy iruigation should be located at least 5 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 irrigation. 4) s) LIMITATIONS This study has been conducted in accordance with generally accepted geotechnical engineering principles and practices in this area at this time. We make no warranty either express or implied. The conclusions and recommendations submitted in this report are based upon the data obtained from the exploratory borings drilled at the locations indicated on Figure l, 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 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 interpolation and extrapolation of the subsurface conditions identified at the exploratory borings and variations in the subsurface conditions may not become evident until excavation is performed. If conditions encountered during construction appear different from those described in this report, we should be notified 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 recommendations, and to verify that the recommendations have been appropriately inteqpreted. Significant design changes may require additional analysis or modifications to the recommendations presented herein. We recommend on-site observation H-P+KUMAR Project No. 18-7-375 -8- of excavations and foundation bearing strata and testing of structural fill by a representative of the geotechnical engineer. Respectfully Submitted, H-P* KUMAR {MdF Robert L. Duran, E. I. Reviewed by: David A. Young, P. RLDlkac L ¿4, EP-?;[6g?-{l ä1¡[1¡"' cc Kaup Engineering - Dale Kaup (dale@kaLrpengineering.com) !"r ,l.r Project No. 18-7-375 È ! d + HAYSTACK ROAD BENCHMARK ! I I ! '\ PÓì!:, I l lÎl*:'¡,'.':¡'¡--*-¡ ,l'I t. I I I \ ì I ì \ I t EORING t ,l I '',..:, '. GARAGE LOT 26 OOOE HAYSTACK I I I I I I I I I I ! I \ I I PROPOSED RESIDENCE LOT 25 . BORING 2 c r.a i I I "",1-k, ',ì," lr't I I I I I I I _ :,11\_1J:J! ¡ ..-t- ,:::,, 15 0 15 APPROXIMATE SCALE-FEET 18-7 -375 H-PryKUMAR LOCATION OF TXPLORATORY BORINGS Fig. I I d BORING 1 EL. 6945.1' BORING 2 E1.6946.9' _0 0 26/12 WC=5.4 -2QA=21 34/1? WC=4.6 DD= 1 09 5 45/12 WC=4.8 *4=41 -2OO=23 37 /12 t-L! TJL! I-t-ù lrJô U 10 F t¡J t¡Jt¡- I Tt-(L UJÕ 3s/12 WC=8.2 DD= I 04 74/12 WÇ=4.7 DD=1 19 153s/12 50/ 4 -20 20 18-7 -375 H-PryKUMAR LOGS OF EXPLORATORY BORINGS Fig.Z I LEGEND NN TOPSOIL; VERY SANDY SILTY CLAY, SCATTERED GRAVEL, FIRM, SLIGHTLY MOIST, BRowN, RooTS SAND (SC-CL), VERY CLAYEY, SCATTERED GRAVEL, MEDIUM DENSE, SLIGHTLY MOIST, BROWN SAND AND GRAVEL (GC_SC), WITH BASALT COBBLES AND PoSSIBLE BoULDERS, CLAYEY To VERY CLAYEY, MEDIUM DENSE, SLIGHTLY MOIST, TAN AND GRAY. RELATIVELY UNDISTURBED DRIVE SAMPLE; 2-INCH t.D. CALTFORNTA LTNER SAMpLE. DR|VE SAMpLE; STANDARD pENETRATTON TEST (SpT), 1 3/8 INCH t.D SAMPLE, ASTM D-1586.i SPLIT SPOON 26/1? DRIVE SAMPLE BLOW COUNT. INDICATES THAT 26 BLOWS OF A 14O-POUND HAMMER FALLING 30 INCHES WERE REQUIRED TO DRIVE THE CALIFORNIA OR SPT SAMPLER I2 INCHES NOTES 1. THE EXPLORATORY BORINGS WERE DRILLED ON JUNE 12,2018 WITH A 4-INCH DIAMETER CONTINUOUS FLIGHT POWER AUGER. 2. THE LOCATIONS OF THE EXPLORATORY BORINGS WERE MEASURED APPROXIMATELY BY PACING FROM FEATURES SHOWN ON THE SITE PLAN PROVIDED. 3. THE ELEVATIONS OF THE EXPLORATORY BORINGS WERE MEASURED BY INSTRUMENT LEVEL AND REFER TO THE BENCHMARK ON FIG. I. 4. THE EXPLORATORY BORING LOCATIONS AND ELEVATIONS SHOULD BE CONSIDERED ACCURATE ONLY TO THE DEGREE IMPLIED BY THE METHOD USED. 5. THE LINES BETWEEN MATERIALS SHOWN ON THE EXPLORATORY BORING LOGS REPRESENT THE APPROXIMATE BOUNDARIES BETWEEN MATERIAL TYPES AND THE TRANSITIONS MAY BE GRADUAL 6, GROUNDWATER WAS NOT ENCOUNTERED IN THE BORINGS AT THE TIME OF DRILLING FLUCTUAÏIONS IN GROUNDWATER LEVEL MAY OCCUR WITH TIME. 7, LABORATORY TEST RESULTS: WC = WATER CONTENT (%) (ASTM D 2216): DD = DRY DENSITY (PCf) (ASTU D 2216);+4 = PERCENTAGE RETAINED ON NO. 4 SIEVE (ASTM D 422); -200= PERCENTAGE PASSING N0. 200 SIEVE (ASTM D 1140). 18-7 -375 H-PryKUMAR LTGEND AND NOTES Fig. 3 x.;!î20_!tcoå þ ->-llEqooooO) \oL.:oäcjr¡J fI¡ @dË nU)r!9L¡JZÉ,9;ßl'oLú É.2.ff.F> ¡-'ñozèo<-t'tn9<2.-ı8sEeoôt,Joo<z:)l--..1..,I!,t" 3-.:Ii,ãs: +rSiÈ!.:. : I àlÈ'-:=: -Éä: i;¡!;llt3 sE ËgËI;¡îEØYIoI(\IìtI+I(oI(t¿) rrr/Y\s - NouvorlosNocrf)IrOf.-FOINIæu:fv-¿¿o-I-J.U7t-JfU1l¿lÉ.t-(nl¡JFz.et-Õ=otnz.o()IJJl.lJ=U).+('li;uóz¿:¡l - 9t@ 'to I SAMPLE 0F: Cloyey Sond wîlh Grovel Molrix FROM:Boring2ae'2.5' WC = 4.6 %, DD = 109 pcf l -ì ADDITIONAL COMPRESSION UNDER CONSTANT PRESSURE DUE TO WETTING ì\ I I \l ì-''. \ I i l l 1 I 1 l 1 j t00SURE - KSF APPLIED PRESSURE - KSF Dt.0 0 -1 -2 -3 -4 0 -1 -2 -3 -4 _q JJ t¡J =v', I zo Ê ô)oØzo(J às JJ l¡, =U) I zo F o =o U1zo(J SAMPLE OF: Cloyey Sond with Grovel Motrix FROM: Boring2@10' WC = 4.7 %, DD = 'l 19 pcf ADDITIONAL COMPRESSION UNDER CONSTANT PRESSURE DUE TO WEÏTING I I ! l I I ___ I I ñ... t.!t r.3ùlt! qpply o^ly to lhc !ompl.! tóstod. fh! l?tling ropod lholl ñol bc æprcduc.d, ôrclPt in r!ll. rilboll th. rritcn opPrdor of Kumd. ôñd &seiot.!, lnc.516ll Conso¡idotion t.ltin9 p.lorñ.d ìn o€codonc. with A5ll¡ 0-{546. I I i I I I 1001.0 Fig.518-7 -375 H.P=KUMAR SWELL-CONSOLIDATION TEST RESULTS 2 roo 90 to 60 50 40 50 20 io o o to 20 50 60 7ø ao 90 100 I E Ë t. CLAY TO SILT COBBLES GRAVEL 11 % SAND LIQUID LIMIT SAMPLE 0F: Cloycy Sond ond Grovel 36%SILT AND CLÂY 23 % PLASIICITY INDEX FROM:BoringlO5 Th.s. l.!l r!!ult! opply only to lh.loñpl.s wh¡ch ware l.slcd. Th. 16sllng raport rho¡l nol ba raproducad, .xcrpl ¡n lull, wìlhoul lhc wrlflc¡ opprovol ol Kumor & Aslociqta!, lnc. Sl.v. onoly!l! l.!ling ls prrformrd in occordonc. vllh ASTM 0422, ASTM Cl56 ond/or ASTM D1l40. HYDROMEIER ANÂLYSIS SIEVE ÀNALYSIS IIME ñEADIilCS ¿4 HRs 7 HRS u.s. slÀNo^Ro sERrEs CLEAR SQUARE OPENINGS rtt' t 1 ta. ---F--1-_+-.1_ -- -+--,----t __++- =7i: +l ----+++= = +__1__+_# ---+- --_r___t --t---t_--ft- -i-+-..Ê -r+=:tr - ---,,+--- SAND GRAVEL FIN E MEDIUM COARSE FIN E COARSE 18-7 -375 H-PryKUMAR GRADATION TTST RESULTS Fig.6 H.PIKUMARTABLE 1SUMMARY OF LABORATORY TEST RESULTSProject No. 1 8-7-375SOILTYPEClayey Sand with GravelClayey Sand and GravelClayey Sand MatrixClayey Sand with Gr¿rvelMatrixClayey Sand with GravelMatrixUNCONFINEDCOMPRESSIVESTRENGTH(osf)2TATTERBERG LIMITSPLASTICINDEX(%lLIQUIDLIMITt%lPERCENTPASSINGNO.200SIEVE23SAMPLE LOCATIONNATURALMOISTURECONTENTNATURALDRYDENSITYGRADATIONBORINGDEPTHGRAVEL%lSAND%t364lto41091195.44.88.24.64.72Y25t0zvz1012