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Home My WebLink AboutSubsoils Report for Foundation Designt*rtiiçl['g''rï:trtr*'"'Ê;;*'* An Employee Owned Compony 5020 County Road 154 Glenwood Springs, CO 81601 phone: (970) 945-7988 fax: (970) 945-8454 email: kaglenwood@kumarusa.com www.kumarusa.com Offìce Locations: Denver (HQ), Parke¡ Colorado Springs, Fort Collins, Glenwood Springs, and Summit Cormty, Colorado November 15,2022 Domoplex, LLC Attn: Slawek Wojciuch 2550 Highway 82, Unit 1084 Glenwood Springs, Colorado 81601 slawek@,domoplex.com RECËruHN Ll di,t{ }. I t-- [-D c $ u hlTY il û iú ir'5 iJ N ¡TY !) [Vi:LrJirM [N'f Project No. 22-7-530 Subject: Subsoil Study for Foundation Design, Proposed Residence, Lot 49, Filing 9, Elk Springs,0034 Vista Place, Garfield County, Colorado Dear Slawek: As requested, Kumar & Associates, Inc. performed a subsoil study for design of foundations at the subject site. The study was conducted in accordance with our agreement for geotechnical engineering services to Domoplex,LLC dated July 27,2022. The data obtained and our recommendations based on the proposed construction and subsurface conditions encountered are presented in this report. Proposed Construction: Plans for the proposed residence were conceptual at the time of our study. The proposed residence will likely be a one- or two-story wood-frame residence with attached garcge located on the site in the area of the pits shown on Figure l. Ground floor could be structural over crawlspace or slab-on-grade. Cut depths are expected to range between about 2 to 5 feet. Foundation loadings for this type of construction are assumed to be relatively light and typical of the proposed type of construction. If building conditions or foundation loadings are significantly different from those described above, we should be notified to re-evaluate the recommendations presented in this report. Site Conditions: The subject site was vacant at the time of our field exploration. Vegetation consists of a grass and weed understory with juniper and pinyon trees. The ground surface was gently sloping down to the south at a grade of about 5.p,çlgqn! Basalt cobbles and boulders were observed on the surface ofthe lot. Subsurface Conditions: The subsurface conditions at the site were evaluated by excavating three exploratory pits at the approximate locations shown on Figure l The logs of the pits are presented on Figure 2. The subsoils encountered, below about 1 to lYz feet oftopsoil, consist of a hard to very hard, sandy silt "caliche" matrix to the maximum explored depth of 3 feet. Basalt -2- cobbles and boulders were encountered in the oaliche matrix in Pits I antl3. Results of a gradation analysis performed on a sample of calcareous matrix (minus 3-inch fraction) obtained from the site are presented on Figure 3. No free water was observed in the pits at the time of excavation and the soils were slightly moist. Foundation Recommendations: Considering the subsoil conditions encountered in the exploratory pits and the noture of the proposed construction, we recommend spread footings placed on the undisturbed natural soil designed for an allowable bearing pressure of 2,500 psf for support of thc proposcd rcsidcncc. Thc soil matrix could tcnd to compress after wetting under load and result in some post-construction foundation settlement. Footings should be a minimum width of 1 6 inches for continuous walls and 2 feet for columns. The topsoil and any loose disturbed soils encountered at the foundation bearing level within the excavation should be removed and the footing bearing level extended down to the undisturbed natural soils. Utility trenches and deep cut areas may require rock excavating techniques such as chipping and blasting. Voids created from boulder removal should be backfilled with road base compacted to at least 95% of standard Proctor density at a moisture content near optimum or with concrete. We should observe the completed tbundation excavation tbr bearing conditions. Bxterior footings should be provided with adequate soil cover above their bearing elevations for frost protection. Placement of footings at least 36 inches below the exterior grade is typically used in this area. Continuous foundation *ull, ,hıîiã-b"- ily reinforced top and bottom to span local anomalies such as by assuming an unsupported length of at least 10 feet. Foundation 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 for the on-site soil or imported gravel as backfill, excluding organics and rock larger than 6 inches. 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 designer based on experience and the intended slab use. A minimum 4-inch laycr of frcc-draining gravcl should be placed beneath below-gradc slabs to facilitatc drainage. This material should consist of minus 2-inch aggregate with less tban 50Yo passing the No. 4 sieve and less than 2Yo passing the No. 200 sieve. 'lhe 4-inch gravel layer placed below slab-at- grade such as the garage can consist of 3/q-inch road base. Kumar & Associates, lnc. o Project No. 22-7-530 --t- All fill materials for support of floor slabs 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 soils or imported granular soils devoid of vegetation, topsoil and oversized rock. Underdrain System: Although free water was not encountered during our exploration, it has been our experience in the areathat local perched groundwater can develop during times of heavy precipitation or seasonal runoff. Frozen ground during spring runoff can create a perched condition. We recommend below-grade construction, such as retaining walls, crawlspace and basement areas (if any), 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 1 foot below lowest adjacent finish grade and sloped at a minimum l%;oto a suitable gravity outlet. Free-draining granular material used in the underdrain system should contain less than 2o/opassingthe No. 200 sieve, less than 50% passing the No. 4 sieve and have a maximum size of 2 inches. The drain gravel backfill should be at least l% feet deep. Surface Drainage: The following drainage precautions should be observed during construction and maintained at all times after 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 95Yo of the maximum standard Proctor density in pavement and slab areas and to at least 90Vo of the maximum standard Proctor density in landscape areas. Free-draining wall backfill should be covered with filter fabric and capped with about 2 feet of the on-site, finer graded soils to reduce surface water infiltration. 3) The ground surface sunounding 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 first 10 feet in unpaved areas and a minimum slope of 3 inches in the first l0 feet in pavement and walkway areas. 4) Roof downspouts and drains should discharge well beyond the limits of all backfill. Limitations: This study has been conducted in accordance with generally accepted geotechnical engineering principles and practices in this area atthis time. We make no warranty either express or implied. The conclusions and recommendations submitted in this report are based Kumar & Associates, lnc. @ Project No. 22-7-530 -4- upon the dat¿ ubtained from the exploratory pits excavated at the locations indicated on Figure I and to the depths shown on Figure 2,theproposed 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, the.n 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 pits and variations in the subsurface conditions may not become evident until excavation is performed. If conditions enc¡untered 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 infonnation. 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 veriff 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. If you have any questions or if we may be of further assistance, please let us know. Respectfully Submitted, Kumnr & Associatcso James H. Parsons, Reviewed by: fr-*a- Steven L. Pawlak, P.E. JHP/kac attaclunents Figure I - Location of Exploratory Pits Figure 2-Logs of Exploratory pits Figure 3 - Gradation Test Results IL ï. 5860¡ ll/8tz Kumar & Associates, lnc, o Project No. 22-7-530 t q 1y r'4r# î 7,r,ar'aa "\/ 'É- \\ R $þ ú î0 Ngo'oo'ooWr I È, $/e Slsc4' o I PITs 89,72' 7 ¡ PlT2 \e{Cb FTS Ë.tg lt''ì 1,,, , rB È\Ë Ël:'1. \ I tq. :.* ft.¡l¡ J rrT A6E IENT L ÅuT#;,L t2 LOT 49 00J4 133,468 sq. ft, 3.064 ec,*-o, t , TïSrA P¿AC8 BI / 46 30 0 APPROXIMATE SCALE-FEET ç $ Fig.1LOCATION OF EXPLORATORY BORINGS22-7-530 Kumar & Associates t i I PIT 1 PII 2 Prï 3 0 0 t- l¡J L¡JtL ITt-fL LJo ) +4=4 -2OO=29 F- LJ l¡JtL I IFfLt!o 5 5 LEGEND TOPSOIL; SANDY SILT WITH OCCASIONAL BASALT COBBLES, ORGANICS, FIRM, SLIGHTLY MOIST, BROWN AND TAN. GRAVEL (GU); elSnlf COBBLES AND BOULDERS, SANDy, SlLTy, DENSE TO HARD, SLtcHTLy MOIST, BALE TAN, CALCAREOUS. SILT (ML); SANDY, HARD, SLIGHTLY MolsT, PALE TAN, CALCAREOUS I I I I DISTURBED BULK SAMPLE PRACTICAL DIGGING REFUSAL. NOTES 1, THE EXPLORATORY PITS WERE EXCAVATED WITH A BACKHOE ON AUGUST 1, 2022. 2, THE LOCATIONS OF THE EXPLORATORY PITS WERE MEASURED APPROXIMATELY BY PACING FROM FEATURES SHOWN ON THE SITE PLAN PROVIDED. 3. THE ELEVATIONS OF THE EXPLORATORY PITS WERE NOT MEASURED AND THE LOGS OF THE EXPLORATORY PITS ARE PLOTTED TO DEPTH. 4. THE EXPLORATORY PIT LOCATIONS SHOULD BE CONSIDERED ACCURATE ONLY TO THE DEGREE IMPLIED BY THE METHOD USED. 5. THE LINES BETWEEN MATERIALS SHOWN ON THE EXPLORATORY PIT LOGS REPRESENT THE APPROXIMAÏE BOUNDARIES BETWEEN MATERIAL TYPES AND THE TRANSITIONS MAY BE GRADUAL. 6. GROUNDWATER WAS NOT ENCOUNTERED IN THE PITS AT THË IIME OI EXCAVATION. PITS WERE BACKFILLED SUBSEQUENT TO SAMPLING. 7. LABORATORY TEST RESULTS:+4 = PERCENTAGE RETAINED oN NO. 4 SIEVE (ASTM D a22); -2OO= PERCENTAGE PASSING NO. 2OO SIEVE (ASTM D 1140). 22-7 -530 Kumar & Associates LOGS OF EXPLORATORY PITS Fig. 2 , & 100 90 80 70 to 50 40 30 20 t0 o HYDROMETER ANALYSIS SIEVE ANALYSIS TIXE RE DIX6S 24 HRS 7 HRSlrr r6vlN ra!|tr I UtN tt U.S. SÎANDARD SERIES -----i--- - I---+----- ---- Lt_ -T- SAND GRAVEL FINE MEDIUM lco¡nse FINE COARSE o to 20 30 40 50 60 70 t0 eo too -tr .o05 t.Ía ts2 DIAMETER OF IN CLAY TO SILT COBBLES GRAVEL 11 26 SAND LIQUID LIMIT SAMPLE OF: Silty Sond ond Grovel 57% PLASTICITY INDEX SILT AND CLAY 29 % FRoM:Plt3A2'-2.5' Thca. lrll rcrullr opply only lo lhG ¡omplc¡ whlch vcrc l.rl.d. Th. l.sllng raporl lhqll ñol b. r.produc.d, .xc.Þt ln full, w¡lhoul th. wrlfl.n oÞp¡ovol ol Kumor & A!toclol.., lnc. si.v. onqlysls l.rllñg ls p.rfom.d ln occordonci v¡lh AslM 06913, ASTM D7928, ASTM C136 o¡d/or ASlt Dll,l0. 22-7 -530 Kumar & Associates GRADATION TEST RESULÏS Fig. 3