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Home My WebLink AboutSubsoil Study for Foundation Design 05.10.2022lGrtir;rïiTin'f#n*iiå*'"5020 County Road 154 Glenwood Springs, CO 81601 phone: (970) 945-7988 fax: (970) 945-8454 email : kaglenwood@kumarusa.com www.kumatusa. comAn Employoc Chrncd Company Offrce Locations: Denver (HQ), Parke¡ Colorado Springs, Forl Collins, Glenwood Springs, and Summit County, Colorado May 10,2022 Myers and Company Attn: Mark Blodgett 555 Basalt Avenue Basalt, Colorado 81621 mb lod gett@m)¡ersandco. com Project No.22-7-287 Subject: Subsoil Study for Foundation Design, Proposed Pool, Homestead 53C, Panorama Ranches, 880 Buck Point Road, Garfreld County, Colorado Gentlemen: As requested, Kumar & Associates, Inc. performed a subsoil study for design of foundations for the proposed swimming pool at the subject site. The study was conducted in accordance with our agreement for geotechnical engineering services to Myers and Company dated April 13, 2022. The data obtained and our recommendations based on the proposed construction and subsurface conditions encountered are presented in this report. Proposed Construction: The proposed pool will be located on the south side of the existing residence and will be l6 feet by 40 feet in plan view and about 3 feet deep at the west end and about 5 feet deep at the east end. The pool will be made of formed concrete. Cut depths are expected to range between about 4 to 6 feet. Foundation loadings for this type of construction are assumed to be relatively light and typical of the proposed type of construction. If pool conditions or foundation loadings are signifrcantly different from those described above, we should be notified to re-evaluate the recommendations presented in this report. Site Conditions: There is an existing2-story residence with a detached garage at the project site. Topography at the site is hilltop with gently sloping terrain down to the south. Vegetation at the building site consists of landscaped lawn, bushes, and trees. Field Exploration: The field exploration for the project was conducted on |l4ay 2,2022. One exploratory boring was drilled at the location shown on Figure I to evaluate the subsurface conditions. The boring was advanced with 4-inch diameter continuous flight augers powered by a truck-urounted CME-458 drill rig. The boring was logged by a replesentative of Kunrar & Associates, Inc. Samples of the subsoils were taken with a lt/"-inch I.D. spoon sampler. The sampler was driven into the subsurface materials at various depths with blows from a 140-pound hammer falling .| 30 inchcs. This tcst is similar to thc standard penetration test described by ASTM Method D- 1586. The penetration resistance values are an indication of the relative density or consistency of the sr.rbsoils. Depths at which the samples were taken ancl the penetration resistance valt¡es 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 subsurfäce conditions encountered at the site is shown on Figure 2. Beneath aboutYz-foot of topsoil, the subsoils consist of silty sand and gravel with scattered cohbles and probable boulders down to the maximum depth explored of 2l feet. Laboratory testing performed on samples obtained from the boring included natural moisture content and gradation analyses. The laboratory testing is summarized in Table 1. No free water was encountered in the boring at the time of drilling and the subsurface materials were slightly moist. Foundation Recommendations: Considering the subsurface conditions encountered in the exploratory boring and the nature of the proposed construction, we recommend the swimming pool be poured against the undisturbed natural soils and designed for an allowable bearing pressure of 2,000 psf. Loose and disturbed soils and any existing frll and topsoil encountered at the foundation bearing level within the excavation should be removed and the bearing level extended down to the r¡ndisturbecl natulral soils. We shoulcl observe the cotnpletecl excavation for bearing conditions. Pool walls acting as retaining structures should be designed to resist a lateral earth pressure based on an equivalent fluid unit weight of at least 45 pcf. Where footings are used, they should be at least 16 inches wide for walls and 2 feet wide for isolated pads and have at least 3 feet of soil cover for frost protection. Swimming Pool: Proper design and construction of below ground pool structures is critical to their satisfactory performance. All swimming pools have a tendency to leak. A small amount of leakage can cause bearing soils to settle and result in pool or slab movement which can widen existing cracks and introduces more water into the subsoils, thereby compounding the problem. Based on these considerations and the subsurface conditions, we suggest the following precautions be taken in the design and construction ofthe proposed pool. l) The pool should be designed and constructed to withstand minor differential movement without serious cracking. Structural fill (if any) below the pool should be compacted to at leastg1Yo of the maximum standard Proctor density near optimum moisture content. Kumar & Associates, lnc. @ Project No. 22-7-287 -3- 2)A minimum 4-inch free-draining gravel layer should be placed beneath the deck and pool. The drainage layer under the pool should slope to a subdrain line or collection point from which water can be removed by pumping or gravity drainage. The drainage layer under the deck should slope to a perimeter drain or be connected to the underpool layer by free-draining backfill. The subdrains should consist of 4 inch diameter perforated PVC pipe sunounded by a minimum of l2 inches of free-draining granular material. The free-draining granular material should consist of minus 2-inch aggregate with less than2Yo passing the No. 200 sieve and less than 50% passing the No. 4 sieve. Slabs-on-Grade: 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, slabs should be separated from all bearing walls and columns with expansion joints which allow unrestrained vertical movement. Control joints should be used to reduce damage due to shrinkage cracking. The requirements forjoint spacing and slab reinforcement should be established by the designer based on experience and the intended slab use. All fill materials for support of slabs-on-grade should be compacted to at least95o/o of maximum standard Proctor density at a moisture content near optimum. Required fill can consist of the on-site granular soils devoid of vegetation, topsoil and rock larger than about 4 inches. 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 boring drilled at the location indicated on Figure I and to the depth shown on Figure 2, 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 boring 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 at once so 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 Kumar & Associates, lnc. @ Project No. 22.7-287 -4- should provide continued consultation and field services during constnrction to review and monitor the implementation of our recommendations, and to veriry that the recommendations have boen appropriatoly interpreted. Significant design changes may require additional anaþsis or modifications to the recommendations presented herein. We recommend on-site observation ofexcavations and foundation bearing strata and testing ofstructural fill by a representative of the geotechnical engineer. If you have any questions or if we may be of further assistance, please let us know. Respectfully Submitted, Kumar & Associateso [nc. Robert L. Duran, P.E. Reviewed by:ffi-,/- Steven L. Pawlak, P.E. RLD/kac attachments Figure 1 - Location of Exploratory Boring Figure 2-Logof Exploratory Boring Figures 3 and 4 - Gradation Test Results Table I - Summary of Laboratory Test Results $n2 l¿,1 Kumar & Associates, lnc. @ ProjectNo. 22-7-287 15526 asE0 HOMESTEAD 53C 6.3ó ACI: ( t\ rNcRassÆcREss --ì EXISTING L .-_--./RESIDENCE \.H0üE5tÀ0 fiECJ 322J73 PROPOSED SWIMMING POOL REC# 35526 2502550 APPROXIMATE SCALE-FEET 22-7 -287 Kumar & Associates LOCATION OF EXPLORATORY BORING Fig. 1 å¡ $ g ¡:¡ BORING 1 LEGEND 0 15/12 WC=9.5 t4=48 -200= 1 7 ñ l--":-.nFI lËrl ¡ TOPSO|L; SAND, SILTY, WITH GRAVEI, FIRM, MO|ST, BROWN, ORGANICS, SOD. 29/6, 50/6 WC=4.8 t4=49 -200= 1 5 SAND AND GRAVET (S}ll-GlJ); SILTY, SCATTERED C0BBLES, PROBABLE BOULDIRS, MEDIUM DTNSE TO DENSE, STIGHTLY MOIST, REO. 5 DRtVt SAMPLE, 1 3/8-|NCH t.D. SPL|T SP00N STANDARD PENETRATION TEST. 70/12 ..r,"DR|VE SAMPLT BLOW COUNT. INDICATES THAT 15 BLOWS 0Ftrt tL A r4o-pouND HAMMER FALLTNG J0 rNcHEs IVERE REoUTRED TO ÐRIVE THE SAMPLER 12 INCHES. 10 68/12t- L¡J t¡J LL I-F(L LJo NOTES 1. THE EXPLORATORY BORING WAS DRILLED ON MAY 2, 2022 WITH A 4-INCH DIAMETER CONTINUOUS FLIGHT POWTR AUGER. 15 75/ 12 2. THT LOCATION OF THE EXPLORAÏORY BORING WAS MEASURED APPROXIMATELY BY PACING FROM FTATURES SHOWN ON THE SITT PLAN PROVIDEO. 3. THI ELEVATION OF THE EXPLORATORY BORING WAS NOT MEASURED AND THE LOG OF THE EXPLORATORY BORING IS PLOTÏED TO DEPTH. 20 s7/12 4. THE EXPLORATORY BORING LOCATION SHOULO BE CONSIDERED ACCURAIT ONLY ÏO THT DEGREI IMPLIEÍ) BY THÊ METHOD USED. 25 5. THE LINES BETWEEN MATERIALS SHOWN ON THE EXPLORATORY BORING LOG REPRESENT THE APPROXIMATE BOUNDARIES BETWEEN MATERIAL TYPES AND THE TRANSIÏIONS MAY BE GRADUAL. 6. GROUNDWATER WAS NOT ENCOUNTERED IN THE BORING AT THE TIME OF DRILLING. 7. LABORATORY TEST RESULTS: WC = WATER CONTENT (%) (ASTM D 2216); +4 = PERCENTAGE RETAINED ON NO. 4 SIEVE (ASTM D 6913); -2OO = PERCENTAGE PASSING NO. 2OO SIEVE (ASTM D 1140). WC=5.1 t4=45 -200= 1 I 22-7 -287 Kumar & Associates LOG OF EXPLORATORY BORING Fig. 2 ê loo go to 70 HYDROMETER ANALYSIS SIEVE ANALYSIS IIYÊ RÊADINCS aôutN tautN ¡utf,24 HRS 7 HRS t!tN tt u.s.GLEAR SOUARE OFENINCS ì i / : o t0 20 50 40 50 60 70 80 90 60 50 ,40 50 20 to 0 6 f e -i-uLr..l7e-2.125 2.O DIAMETER OF PARTICLES IN MILLIMEÎERS 152 CLAY TO SILT COBBLES GRAVEL 18 % SAND LIQUID LIMIT SAMPLE OF: Sllty Sond ond Groval 35% PLASTICITY INDEX SILT AND CLAY 17 % FROM:BorlnglOl' ÎIME READITGS U.S. STANOARD SERIES Hns too 90 ao 70 60 50 40 30 20 10 -t-t-o*e -...0 to 20 50 40 50 60 70 lo 90 r00 I ã É 2 , -1. 0 :..-.oot : *:L, -- r_-r..otg .o37 .1. r-..1*r-l-r*. .o75 ¡ : rl ¡ r rll OIAMETE l.t6 2.3ô 1.73 9.5 2.OIN MILLIMEÏERS CLAY TO SILT COBBLES GRAVEL 49 % SANO LIOUID LIMIT SAMPLE OF: Silty Sond ond Grovel 36% PLASTICITY INDEX SILT AND CLAY I5 % lo lhô FROM:BorìnglO4'sompl€s vhlch lh!l.rllng rcporl tholl not bc r.prcduc.d, cxccÞl lh lull, vllhoul lhc w¡ltlcn opprovol of Kumdr t A.¡oclol.r, lñc.Si.v. onolysl¡ l.tllng b p.rtorm.d lnqccordqnc. Tlth ASTM 069.13, ASTM 07928, ASril Cl56 oñd/or ASIM Dll,l0. SAND GRAVEL FINE MEDIUM COARSE FIN E COARSE SAND GRAVEL FIN E MEDTUM ICOARSE FINE COARSE HYOROMÉIER ANALYSIS SIEVE ANALYSIS : l GRADATION ÏEST RESULTS Fig. 322-7 -287 Kumar & Associates .ã $ ë ã å É ËI 100 ¡0 t0 70 ô0 50 40 lo 20 t0 o o t0 to 30 ,to 50 80 70 l0 90 r00 T H I H OIAMETER OF .a26 PARIICLES IN CLAY TO SILT COBBLES GRAVÊI 15 % SANO LIQUID LIMIT SAMPLE OF: Sllty Sond ond Grovel 37% PTASTICITY INDEX SILT AND CLAY 1A '¿ FRoM: Borlng 1 o 7' E 10' (Comblnad) lhc¡s lc¡l rcrulh opply only lo lha rompl4 whloh w!r. lldcd. Ìh!l.illng r.port rholl nol b. rcprcduccd, .xcrÞl lñ full, wllhoul lh. vtlll¡n opÞrcvol of Kumqr & ^¡soolol.., lno. Sl.v. onoly.¡. l.tllng lt p.lormtC ln ocoordqnc! ellh ASTI¡ D6915. AslM D7928, ASTI¡ Cl56 ondlor ASTM Dll,l0. HYDROMEÎER ANALYSIS SIEVÊ ANALYSIS clt t sôu^nE oFEt{Dtcs atL. I ltr. u.a. I tI I I I -1 i l I\/ .l I ! ri I f I r l ì SAND GRAVEL FINE COARSEFINEMEDIUM ICOARSE 22-7 -287 Kumar & Associates GRADATION TEST RESULTS Fig. 4 tGrt*iË*fi#:lfßHn¡',i";å*'* è: TABLE 1 SUMMARY OF LABORATORY TEST RESULTS No.22-7-287 SAMPL LOCATION SOIL TYPE NATURAL DRY DENSIW ln.fì GRAVEL (:/"1 SAND %t PERCENT PASSING NO. 200 srEVE LIQUID LIMIT I't \ PLASTIC INDEX P/.1 losll UNCONFINED COMPRESSIVE STRENGTHBORING fftì DEPTH t%l NATURAL MOISTURE CONTENT Silty Sand and Gravel9.3 48 35 17II l5 Silty Sand and Gravel44.8 49 36 5t l8 Silty Sand and Gravel7 and l0 Combined 5.1 45