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Home My WebLink AboutSubsoil Study for Foundation Design 03.22.2024Ktnfl|,.p11fl'.Tifflttrf 'Yrd.** An Employcc Owncd Gompony 5020 County Road 154 Glenwood Springs, CO 81601 phone: (970)945-1988 fax: (970) 945-8454 email: kaglenwood@kumarusa.com www.kumarusa,com Office Locations: Denver (HQ), Parker, Colorado Springs, Fort Collins, Glenwood Splings, and Summit County, Colorado SUBSOIL STUDY FOR FOUNDATION DESIGN PROPOSED STEEL SHOP BUILDING O COUNTY ROAD 236 GARFTELD COUNTY, COLORADO PROJECT NO.24-7-110 MARCH 22,2024 PREPARED FOR: ALBERTO PIZARO 1201 BEDROCK CIRCLE srLT, coLoRADO 81652 Apizarro 1980@gmail.com TABLE OF CONTENTS PURPOSE AND SCOPE OF STUDY ... PROPOSED CONSTRUCTION SITE CONDITIONS FIELD EXPLORATION SUBSURFACE CONDITIONS DESIGN RECOMMENDATIONS ...... FOUNDATIONS FLOOR SLABS UNDERDRAIN SYSTEM ............... SURFACE DRAINAGE LIMITATIONS. FIGURE 1 - LOCATION OF EXPLORATORY BORINGS FIGURE 2 - LOGS OF EXPLORATORY BORINGS FIGURE 3 . LEGEND AND NOTES FIGURE 4 - SWELL-CONSOLIDATION TEST RE,SULTS TABLE 1- SUMMARY OF LABORATORY TEST RESULTS 1 1 -1 -3- a ,| a 1 -4- -4- -5- Kumar & Associates, lnc. @ Project No.24-7-110 PURPOSE AND SCOPE OF STUD} This report presents the results of a subsoil study for a proposed steel shop building to be located at 0 Connty Road 236, 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 Alberto Pizaro dated January 15,2024. 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 analyzedto 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 building will be a single-story steel frame and metal-sided structure with a slab-on-grade floor located on the site in the area of the exploratory borings shown on Figure 1. Grading for the structure is assumed to be relatively minor with cut depths between about 3 to 4 feet. We assume relatively light to moderate 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 site is shown on Figure 1 and located just south of County Road 236 (Harness Lane). The site was occupied by an existing residence and barn. The proposed metal building is to be located to the east of the existing bam. The ground surface was gently sloping down to the southwest. Vegetation consists of native grass and weeds. FIELD EXPLORATION The field exploration for the project was conducted on February 29,2024. Two exploratory borings were drilled at the locations shown on Figure 1 to evaluate the subsurface conditions. Kumar & Associates, lnc. o Project No.24-7-110 ^-z- The borings were advanced with 4-inch diameter continuous flight augers powered by a track- mounted CME-45 drill rig. The borings were logged by a representative of Kumar & Associates. Samples of the subsoils were taken with a 2-inch I.D. spoon sampler. The sampler was 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 Logs of Exploratory Borings, Figure 2. The samples were retumed 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, consist of 2 to 3 feet of existing silty sand fill material underlain by medium dense very clayey silty sand to the maximum explored depth of25 feet deep. Laboratory testing performed on samples obtained from the borings included natural moisture content and density, and percent finer than sand size gradation analyses. Results of swell- consolidation testing performed on relatively undisturbed drive samples of the silty clayey sand soils, presented on Figure 4, indicate low to moderate compressibility under conditions of loading and wetting. The sample tested from Boringl at a depth of 9 feet exhibited a low hydrocompression potential when weffed under a constant 1,000 psf surcharge. The laboratory testing is summarizedin Table 1. No free water was 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, the building can be founded with spread footings or thickened slab sections bearing on the natural sand soils with a low risk of settlement. A lower risk of sefflement would be to place the footings or thickened slab sections on2 to 3 feet of removed and replaced sand soils moisture conditioned to within2 percent of optimum moisture content and compacted to at least 98 percent of the standard Proctor density. The design and construction criteria presented below should be observed for a spread footing or thickened slab foundation system. Kumar & Associates, Inc. o Project No.24-7-110 -J- 1)Spread footings placed on the undisturbed natural soils or compacted structural fill should be designed for an allowable bearing pressure of 1,500 psf. Based on experience, we expect movement of footings designed and constructed as discussed in this section will be about I to 2 inches or less. Monolithic slab foundation sections placed on the natural soils should be designed for an allowable bearing pressure of 1,500 psf. Based on experience, we expect movement of footings designed and constructed as discussed in this section will be about I to l% inches depending on the subgrade conditions. 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 typically used in this area. Reduced frost cover for a thickened slab foundation should be feasible provided ground insulation is provided. Continuous foundation walls should be well reinforced top and bottom to span local anomalies such as by assuming an unsupported length of at least 12 feet. Thickened slab sections should be well reinforced with both longitudinal and transverse steel. Foundation walls acting as retaining structures, if any, should also be designed to resist alateral earth pressure coffesponding to an equivalent fluid unit weight of at least 50 pcf. All topsoil, loose disturbed soils, and any existing fill should be removed and the footing bearing level extended down to the relatively firm natural soils. The exposed soils in foundation areas should then be moistened and compacted. A representative of the geotechnical engineer should observe all foundation excavations and test structural fill compaction on a regular basis prior to concrete placement to evaluate bearing conditions. 2) 3) 4) 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 layer of relatively well graded sand and gravel should be placed immediately beneath slabs for support. This s) 6) 7) Kumar & Associates, Inc. o Project No.24-7110 -4- material should consist of minus 2-inch aggregate with at least 50Yo retained on the No. 4 sieve and less than I2o/o passing the No. 200 sieve. All fill materials for support of floor slabs should be compacted to at least 95%o of maximum standard Proctor density at a moisture content near optimum. Required fill can consist of the on-site granular soils devoid of topsoil and oversized (plus 6-inch) rocks, or of imported CDOT Class 6 base course. UNDERDRAIN SYSTEM Although free water was not encountered during our exploration, it has been our experience in the area and where clay 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. For the proposed slab-at-grade construction, an underdrain system is not required. We recommend below-grade construction, such as retaining walls and basement areas, be protected from wetting and hydrostatic pressure buildup by an underdrain system. If installed, the drains should consist of rigid PVC 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 %o/oto a suitable gravity outlet. Free-draining granular material used in the underdrain system should contain less than 2Yo passingthe 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 1lz feet deep and covered with filter fabric such as Mirafi 140N or 160N. SURFACE DRAINAGE The following drainage precautions should be observed during construction and maintained at all times after the building has been completed: 1) Inundation of the 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 95%o of the maximum standard Proctor density in pavement and slab areas and to at least 90o/o 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 slope of 6 inches in the first 10 feet in unpaved areas and a minimum slope of 2/zrnches in the first 10 feet in paved areas. 4) Roof downspouts and drains should discharge well beyond the limits of all backfill. Kumar & Associates, lnc. @ Project No.24-7-110 5 Landscaping which requires regular heavy irrigation should be located at least 5 feet from foundation walls. LIMITATIONS This study has been conducted in accordance with generally accepted geotechnical engineering principles and practices in this areaatthis 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 1, 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 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 frll by a representative of the geotechnical engineer. Respectfully Submitted, Kumar & Associates, Robert L. Duran, P.E. Reviewed by: s) b Daniel E. Hardin, P.E. RLDlkac r573?0; Kumar & Associates, lnc,6 Project No.24-7-110 .: j 100 APPROXIMATE SCALE_FEET 24-7 -1 10 Kumar & Associates LOCATION OF EXPLLORATORY BORINGS Fig. 1 ! t a , BORING 1 BORING 2 0 0 7/12 8/ 12 5 11/12 1o/ 12 tNC=7.2 DD= 1 03 -200=35 5 10 11/12 WC=7.8 DD= 1 08 -2OO=48 13/ 12 WC=4.8 DD= 1 05 10 Ftrj LJI! I-F(L ulo 15/ 12 WC=5.8 DD= 1 09 12/12 15 F UJ LrltL I-F o_ tlJo 15 20 20/ 12 22/12 20 25 22/12 25 24-7-110 Kumar & Associates LOGS OF EXPLORATORY BORINGS Fig. 2 e I j : e a LEGEND N TOPSOIL; CLAYEY SILT, SANDY WITH SCATTERED GRAVEL, FIRM, SLIGHTLY MOIST, LIGHT BROWN, ROOTS. FILL; SILTY SAND WITH GRAVEL, LOOSE, SLIGHTLY MOIST, BROWN SAND LIGHT (SM); VERY SILTY, CLAYEY, SCATTERED GRAVEL, MEDIUM DENSE, SLIGHTLY MOIST, BROWN TO BROWN. DRIVE SAMPLE, 2-INCH I.D. CALIFORNIA LINER SAMPLE. .r.. DRIVE SAMPLE BLOW COUNT. INDICATES THAT 7 BLOWS OF A 14O-POUND HAMMER'/ '' FALLTNG Jo TNcHES wERE REQUTRED To DRrvE THE sAMpLER 12 rNcHEs. NOTES 1. THE EXPLORATORY BORINGS WERE DRILLED ON FEBRUARY 29, 2024 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. 5. THE ELEVATIONS OF THE EXPLORATORY BORINGS WERE NOT MEASURED AND THE LOGS OF THE EXPLORATORY BORINGS ARE PLOTTED TO DEPTH. 4. THE EXPLORATORY BORING LOCATIONS 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 7. LABORATORY TEST RESULTS: WC = WATER CONTENT (%) (ASTM D2216); DD = DRY DENSITY (PCt) (ASTM D2216); _2OO= PERCENTAGE PASSING NO. 2OO SIEVE (ASTM Dl140). 24-7 -1 10 Kumar & Associates LEGEND AND NOTES Fig. 3 & E I tsg SAMPLE OF: Very Silty Cloyey Sond FROM:Boringl@9' WC = 7.8 %, DD = 108 pcf -20O = 48 % ADDITIONAL COMPRESSION UNDER CONSTANT PRESSURE DUE TO WETTING l l :1 :l:: :: )q JJtll =tn I z.o F- o =oazo(J 1 0 1 2 -5 -4 .l.0 APPLIED PRESSURE - KSF 100 JJ Lrl =tn I z.otr o =oaz.oO 1 0 1 2 1.0 APPLIED PRESSURE - KSF t0 SAMPLE 0F: Very Silty Cloyey Sond FROM:Boring2@4' Y'lC = 7.2 %, DD = 105 pcf -2OO = 35 % : : : : : NO MOVEMENT UPON WETTING 24-7 -1 10 Kumar & Associates SWELL_CONSOLIDATION TEST RESULTS Fig. 4 l(+rI l(umar & Associates, Inc. o Geotechnical and Materials Engineers and Environmental Scientists TABLE 1 SUMMARY OF LABORATORY TEST RESULTS Project No.24-7-1{0 AfiERBERG LIMITS UNCONFINED COMPRESSIVE STRENGTHLIQUID LIMIT PLASTIC INDEX SOIL TYPE Very Silty Clayey Sand Very Silty Clayey Sand Very Silty Clayey Sand Very Silty Clayey Sand PERCENT PASSING NO. 200 stEvE 48 35 GRADATION SAND (%l GRAVEL %l NATURAL DRY DENSITY (ocfl 108 109 103 105 NATURAL MOISTURE CONTENT (%) 7.8 s.8 7.2 4.8 SAMPLE LOCATION DEPTH (ft) 9 t4 4 9 BORING 1 2 b 27AN 2703/0 27C]3p0 2705S0 27WA I 27Mq 27c6/ot**,-27W 390 33'6" N 390 32'55'N Rs s 390 33',5" N 390 3255'N Rsa t 1 a R 3 N 3 F F :,1.'tt E R F R $t'- N 3 E $*,.. ..-b*." . .1. N b 5RN A 27c24o 27AN z7jgD 27cpp0 Map Scale: 1:2,360 ifprinted on A landscape (11" x 8.5") sheel ,Meters0 30 60 1n 180 Feet0 1m 2m 400 6m Mapprojectjon:WebMercator Comercoordinates:WGS84 Edgetics:UTMZone13NWGSB4 27c44o Web Soil Survey National Cooperative Soil Survey 27Uq 270S0 USDA - Natural Resources Conservation Service 5113t2024 Page 1 of 3 Soil Map-Rifle Area, Colorado, Parts of Garfield and Mesa Counties =F-b 27cgo 27cE€o 27WD USDA - Natural Resources Conservation Service Soil Map-Rifle Area, Colorado, Parts of Garfield and Mesa Counties Web Soil Survey National Cooperative Soil Survey 5113t2024 Page 2 of 3 MAP LEGEND MAP INFORMATION The soil surveys that comprise your AOI were mapped at 1:24,000. Warning: Soil Map may not be valid at this scale. Enlargement of maps beyond ihe scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale. Please rely on the bar scale on each map sheet for map measurements. Source of Map: Natural Resources Conservation Service Web Soil Survey URL: Coordinate System: Web Mercator (EPSG:3857) Maps from the Web Soil Survey are based on the Web Mercator projeciion, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Albers equal-area conic projection, should be used if more accurate calculations of distance or area are required. This product is generated from the USDA-NRCS certified data as of the version date(s) listed below. Soil Survey Area: Rifle Area, Colorado, Parts of Garfield and Mesa Counties Survey Area Data: Version 16, Aug 22,2023 Soil map units are labeled (as space allows) for map scales 'l :50,000 or larger. Date(s) aerial images were photographed: Aug 25, 2021-Sep 5,2021 The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting of map unit boundaries may be evident. Area of lnterest (AOl)El Spoil Area d StonySpot ffi VeryStonySpot S Wet Spot l, Oiher .' Special Line Features Water Features Streams and Canals Transportation 111 Rails ae lnterstate Highways frda US Routes :1:: Major Roads Local Roads Background I Aerial Photography Area of lnterest (AOl) Soils tf Soil Map Unit Polygons |r,i Soil Map Unit Lines I Soil Map Unit Points Special Point Features tg Blowout Bl Borrow Pit H Clay Spot d! Closed Depression H Gravel Pit ;i Gravelly Spot S Landfill A, Lava Flow ;l* Marsh or swamp fr Mine or Quarry g Miscellaneous Water f| Perennial Water W Rock Outcrop + Saline Spot ;": sandy spot €l Severely Eroded Spot * Sinkhole h Slide or Slip @ Sodic Spot Soil Matr-Rifle Area, Colorado, Parts of Garfield and Mesa Counties Map Unit Legend '100,0%27.5Totals for Area of lnterest 1s%0.4f ldefonso stony loam, 25lo 45 percent slopes 34 98,5olo27.1Arvada loam, 1 to 6 percent slopes 3 Percent of AOIAcres in AOIMap Unit NameMap Unit Symbol TJSDArr Natural Resources Gonservation Service Web Soil Survey National Cooperative Soil Survey 5t13t2024 Page 3 of 3 Map Unit Description: Arvada loam, 1 to 6 percent slopes--Rifle Area, Colorado, Parts of Garfield and Mesa Counties Rifle Area, Golorado, Parts of Garfield and Mesa Gounties 3-Arvada loam, 1 to 6 percent slopes Map Unit Setting National map unit symbol: jnxv Elevation: 5,100 to 6,200 feet Farmland classification: Not prime farmland Map Unit Composition Aruada and similar so/s; B0 percent Minor components; 5 percent Esfimafes are based on observations, descriptions, and transects of the mapunit. Description of Arvada Setting Landform : Terraces, fans Landform position (three-dimensional) : Tread Down-slope shape; Convex, linear Across-s/ope shape; Convex, linear Parent material: Highly saline alluvium derived from sandstone and shale Typical profile H1 -0 fo3rnches; loam H2 - 3 to 17 inches: silty clay loam H3 - 17 to 60 inches; silty clay loam Properties and qualities S/ope;lto6percent Depth to restrictive feature: More than B0 inches Drainage c/ass: Well drained Runoffclass; High Capacity of the most limiting layer to transmit water (Ksat): Moderately low to moderately high (0.06 to 0.20 in/hr) Depth to water fable: More than B0 inches Frequency of f/ooding: None F reque ncy of pondlng: None Calcium carbonate, maximum content: 10 percent Gypsum, maximum content:2 percent Maximum salinity: Slightly saline to strongly saline (4.0 to 16.0 mmhos/cm) Sodium adsorption ratio, maximum; 30.0 Available water supply, 0 to 60 inches: Moderate (about 8.0 inches) lnterpretive groups Land capability classification (irrigated): 7s Land capability classification (nonirrigated) : 7 s USDA - Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 5t13t2024 Page 1 of 2 Map Unit Description: Arvada loam, 1 to 6 percent slopes--Rifle Area, Colorado, Parts of Garfield and Mesa Counties Hydrologic Soil Group: C Ecologicalsife: R034BY006UT - Alkali Flat (Greasewood) Hydric so/ raflng.' No Minor Components Wann Percent of map unit: 5 percent Landform: Terraces Landform position (three-dimensional) : Tread Hydric soil rating: Yes Data Source lnformation Soil Survey Area: Survey Area Data Rifle Area, Colorado, Parts of Garfield and Mesa Counties Version 16, Aug 22,2023 USDA:Natural Resources Gonservation Service Web Soil Survey National Cooperative Soil Survey 5t13t2024 Page 2 of 2 regi CS LO RA D O"S Deeislon S[pptrrt Systetrs flrifcF r fi{n Map Viewer * Well Constructed I Final Permit r Ground Water X Geophysical Log Lj County Legend t, . i: 5 lrI Location Notes 1,169 0 585 1,169 Feet fi This product is for informational purposes and may not have been prepared for, or be suitable for legal, engineering, or surueying purposes. Users of this information should review or consult the primary data and information sources to ascerfain the usability of the information. Date Prepared: 511312024 1 :19:03 PM1: 7,016