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Home My WebLink AboutSubsoils Report for Foundation Designrcrf Hiçlfi'åiffËtrnr'riå*'" An Employes Ownod Compony 5020 County Road 154 Glenwood Springs, CO 81601 phone: (970) 945-7988 fax: (970) 945-8454 email : kaglenwood@kumarusa.com www.kumarusa.com Ofüce Locations: Denver (HQ), Parker, Colorado Springs, Fort Collins, Glenwood Springs, and Summit Comty, Colorado SUBSOIL STUDY FOR FOUNDATION DESIGN PROPOSED RESIDENCE LOT 7, BLOCK 9 MONUMENT CREEK VILLAGE BATTLEMENT MESA 543 PONDEROSA CIRCLE GARFIELD COUNTY, COLORADO PROJECT NO.23-7-440 SEPTEMBER7,2023 PREPARED FOR: LUIS VARGA 792 CASTLE VALLEY BOULEVARI) NEW CASTLE, COLORADO 81647 umbllc2020@smail.com -í a a) s'lstJ IID '- $a Ltr TABLE OF CONTENTS PURPOSE AND SCOPE OF STUDY .... PROPOSED CONSTRUCTION SITE CONDITIONS,..,.......... FIELD EXPLORATION.... SUBSURFACE CONDITIONS DESIGN RECOMMENDATIONS FOUNDATIONS.. FLOOR SLABS.... UNDERDRAIN SYSTEM LIMITATIONS FIGURE 1 - LOCATION OF EXPLORATORY BORING FIGURE 2 -LOG OF EXPLORATORY BORING FIGURE 3 - SWELL-CONSOLIDATION TEST RESULTS TABLE I - SUMMARY OF LABORATORY TEST RESULTS 1 I I -)_ -2- ......- 3 - _L- -4- Kumar & Associates, lnc. @ Project No.23-7-4É10 PURPOSE AND SCOPE OF STUDY This report presents the results ofa subsoil study for a proposed residence to be constructed on LotT,Block 9o Monument Creek Village, Battlement Mesa, 543 Ponderosa Circle, 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 geotechnical engineering services to Luis Varga dated July 20,2023. 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, 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 foundations. 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 Building plans for the proposed residence were preliminary atthe time of our study and are assumed to consist of a wood-frame structure above a crawlspace with a slab-on-grade garage. Grading for the structures 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, locations, 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 property is vacant and vegetated with sparse grass and weeds. The ground surface appeared to have been graded for subdivision development. Lot 7 is bordered on the north by Ponderosa Circle. The ground surface is relatively flat and slopes gently down to the northeast. FIELD EXPLORATION The field exploration for the project was conducted on August 29,2023. One exploratory boring was drilled at the approximate location shown on Figure 1 to evaluate the 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 Kumar and Associates. Kumar & Associates, lnc. o Project No. 23-7-M0 -2- Samples ofthc subsoils wcrc takcn with l% and 2-inch l.D. spoon samplers. 'I'he samplers were driven into the subsoils at various depths with blows from a 140 pound hammcr 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 ofthe 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, below about one foot of topsoil, consist of very stiff to hard, sandy silt and clay to sandy silty clay with gravel down to about 131/zfeet, underlain by dense, silty clayey sandy gravel and cobble basalt rocks down to the bottom of the boring, 17 feet. Drilling in the coarse granular soils with auger equipment was difficult due to the cobbles and possible boulders and practical auger drilling refusal was encountered in the deposit. Laboratory testing performed on samples obtained from the boring included natural moisture content and density and percent finer than sand size gradation analyses. Results of swell- consolidation testing performed on a relatively undisturbed drive sample of the upper silt soil, presented on Figure 3, indicate low compressibility under existing low moisture conditions and light loading and a minor expansion potential when wetted. The laboratory testing is summarized in Table l. No free water was encountered in the boring at the time of drilling and the subsoils were slightly moist. DESIGN RECOMMENDATIONS FOUNDATIONS 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 on the natural subsoils. Our experience is that the upper fine-grainetl soils tend to compress when wetted under load and the expansion potential measured on the sample tested can be ignored in the foundation design. 'lhe design and construction criteria presented below should be observed for a spread footing foundation system. 1) Footings placed on the undisturbed natural soils should be designed fbr an alluwable bearing pressure of[50,0¡,q[. Based on experience, we expect initial settlement of footings dcsigncd and constructed as discussed in this section will be about 1 inch or less. There could be some additional differential movement of footings if the bearing soils become wet. Kumar & Associates, lnc. o Projec{ No. 23.7.440 J 2) The footings should have a gFirqgm wirlth of 10 i{rctres tor continuous walls and @3) pxtèrioi 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 i6,t"ry,t*elow exterior grade is typically used in this area. 4) Continuous foundation walls should be heavily 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 lateral earth pressure computed on the basis of an equivalent fluid unit weight of at least 55 pcf for backfill consisting of the onsite soils. 5) The topsoil and any loose or disturbed soils should be removed and the footing bearing level extended down to the undisturbed natural soils. The exposed soils in footing areas should then be moistened and compacted. 6) A representative ofthe 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 with a risk of movement similar to the foundation. 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 relatively well graded sand and gravel, such as Class 6 base course, should be placed beneath slabs-on-grade for support. This material should consist of minus 2-inchaggregate with at least 50o/o retained on the No. 4 sieve and less than l2%o passing the No. 200 sieve. All fill materials for support of floor slabs should be compacted to at least95Yo of maximum standard Proctor density at a moisture content near optimum. Required fill can consist of the onsite soils or imported granular soils devoid of vegetation, topsoil, and oversized rock. UNDERDRAIN SYSTEM The proposed shallow crawlspace and slab-on-grade garuge should not require an underdrain system provided positive drainage away from the exterior of the house is maintained. If installed (such as for a basement level), 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 Kumar & Associates, lnc. @ Project No. 23-7-4/,0 -4- grude und slopcd at a minimum lYoto a suitable gravity oul.lel. or sump and pump. llue to the relatively tlat lot, it may be impractical to daylight a perimeter foundation dmin. We reconunentl against installing drywells for disposal of porimetor drain woter due to the hard clay soil. Frcc- tlraining granttlar material used in the underdrain system should contain less than ?% passing the No. 200 sieve, less than 50Yo passing the No. 4 sieve and have a maximum size of 2 inches. The drain gravel backfill should be at least lYzfeetdeep. SURFACE DRAINAGE The following drainage precautions should be observed during construction and maintained at all times afrer the residence has been completed: l) 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 95o/o of the maximum standard Proctor density in pavement and slab areas and to at least 90% 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 directions. We recommend a minimum slupe of 12 inches in the first l0 feet ln unpaved areas and a minimum slope of 3 inches in the first l0 feet in paved areas. Free-draining wall backfill should be covered with filter fabric and capped with about 2 feet of the on-site soils to reduce surface water infiltration. 4) Roof downspouts and drains should discharge well beyond the limits of all backfill. 5) Landscaping which requires regular heavy irrigation 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. 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 l, the proposed type of construction and our expericnce in the area. Our services do not include detennining the plesence, prevention or possibility of mold or other biological contaminants (MOBC) developing in the future. If the olient is concemed 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 Kumar & Associates, lnc. @ Project No. 23.7-U0 -5- 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 veriry 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, Kumar & Steven L. Reviewedby: Daniel E. Hardin, P.E. SLPlkac Kumar & Associates, lnc. o Project No, 23-7-44A ¡ I E t ñ 3 -------< POTVOC\ arro,a I I ILOT 8 I BORING I oI I // I /I LOT 7 I // I FILING 9 MONUMENT CREEK VILLAGE / I // /LOT 6// 5¿3 PONDEROSA CIRCLE NOT TO SCALE 23-7-440 Kumar & Associates LOCATION OF EXPLORATORY BORING Fig. 1 I ¡ ¡ ! BORING 1 LEGEND N TOPSO|L; 0RGANIC SANDY SILT, FIRM, BR0WN 0 s6/12 srLT (ML); SLIGHTLY SANDY, SLIGHTLY CLAYEY, VERY STIFF TO HARD, MOIST, LIGHT BROWN, LOESS. 5 18/12 WC=5.0 DD= 1 07 CI.AY HARD, (Cr); StlfV, SANDY, SCATTERED GRAVEL, VERY STIFF T0 SLIGHTLY MOIST, LIGHT BROIYN, CALCAREOUS. GRAVEL AND COBBLES PROBABLE BOULDERS, BASALT ROCK. (GM-GC); SILTY, CLAYEY, SANDY, DENSE, SLIGHTLY MOIST, GRAY-BROWN, F l¿¡ UJl! I-FfL L¡lô 10 34/12 WC=8.9 DD=1 05 -200=57 DRIVE SAMPLE, 2-INCH I.D. CALIFORNIA UNER SAMPLE. I DRTVE SAMPLE, r 5/8-INCH l.D. SPLIT SP00N STANDARD PENETRATION TEST. 15 35/6, 50/6 zc rr o DRIVE SAMPLE BLOW COUNT. INDICAIES THAT 36 BLOIYS 0F¿vr t' ^ f40-p0uND HAMMER FALLTNG 30 INCHES WERE REQUIRED TO DRIVE THE SAMPLER f2 INCHES. I PRACTICAL AUGER REFUSAL. WHERE SHOWN ABOVE BOÏÍOM OF BORING, INDICATES THAT MULTIPLE ATTEMPTS WHERE MADE TO ADVANCE THE HOE. 20 NOTES 1. THE EXPLORATORY BORING WAS DRILLED ON AUGUST 29' 2023 WTH A 1-INCH DIAMETER CONTINUOUS FLIGHT POWER AUGER. 2, THE LOCATION OF THE EXPLORATORY BORING WAS MEASURED APPROXIMATELY BY PACING FROM FEATURES SHOWN ON THE SITE PI.AN PROVIDED. 5. THE ELEVATION OF THE EXPLORATORY BORING WAS NOÏ MEASURED AND THE LOG OF THE EXPLORATORY BORING IS PLOTTED TO DEPTH. 1. THE EXPLORATORY BORING LOCATION SHOULD BE CONSIDERED ACCURATE ONLY TO THE DEGREE IMPLIED BY THE METHOD USED. 5. THE LINES BETWEEN MATERIALS SHOWN ON THE EXPLORATORY BORING LOG REPRESENT THE APPROXIMATE BOUNDARIES BITIVEEN MATERIAL TYPES AND THE TRANSITIONS MAY BE GRADUAL. 6. GROUNDWATER WAS NOT ENCOUNTERED IN THE BORING AT THE TIME OF DRILLING. 7. LABORATORY TEST RESULTS: WC = WATER CONTENT (,6) (ASTM D 2216)I DD = DRY DENSITY (pct) (lSrU D 2216)t -200 = PTRCENTAGE PASSING NO. 200 SIEVE (ASTM D r1&). Fis. 2LOG OF EXPLORATORY BORINGKumar & Associates23-7-440 Ê ¡ E t ! ! Ia ,lt I SAMPLE OF: Sondy Cloyey Silt FROM:Boringl()4' WC = 5.0 24, DD = 107 pcf EXPANSION UNDER CONSTANT PRESSURE UPON WETTING nã m ddt. opflt sy b th.mñdn ld.d Îla tdlE nFfr.hll mt b EFÞdud, .Ept ln full, t'M b. rritbn opprûiEl of K0mr ond kæ|tu, lñc Sr.iCoñlldffi tdiq pdomd lno@dôÉ úü m D-¡ff. I N JJ l¡J =Ø I zo F ôfoØto() 0 1 2 1 1,0 APPLIED PRESSURE - KSF t00 23-7-440 Kumar & Associates SWELL_CONSOLIDATION TEST RESULTS Flg. 3 lcrti,iffifimfmfl{Í$ü** ::; TABLE 1 SUMMARY OF LABORATORY TEST RESULTS ilSATPLE LOCATIOI¡ SOIL TYPEPLASTIC I}IDEX tì fo¡ll UNCOl{FINED coflPRESStVE STRËiIGfH SAI{D (96) PERCENT PASSING NO. 200 slEvE fïol TIQUID LITfT NATURAL DRY DEI{SITY lbclì GRAVEL (%)BORING í0 DEPÍH NATURAL ilorsluRE COI{TENI Sandy Clayey Silt5.0 t07I4 Sandy Silty Clay5798.9 105