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Home My WebLink AboutSoils Report 04.25.2018Hp�KUMAR Geotechnical Engineering 1 Engineering Geology Materials Testing 1 Environmental 5020 County Road 154 Glenwood Springs, CO 81601 Phone: (970) 945-7988 Fax: (970) 945-8454 Email: hpkglenwood@kumarusa.com Office Locations: Denver (I -IQ), Parker, Colorado Springs, Fort Collins, Glenwood Springs, Summit County, Colorado SUBSOIL STUDY FOR FOUNDATION DESIGN PROPOSED STEEL BUILDING LOT 5, RIFLE CREEK HIGHLANDS COUNTY ROAD 317 GARFIELD COUNTY, COLORADO PROJECT NO. 18-7-231 APRIL 25, 2018 PREPARED FOR: MIKE RAINEY 3177 WEST 31st COURT RIFLE, COLORADO 81650 444re]oad@gmail.com TABLE OF CONTENTS PURPOSE AND SCOPE OF STUDY - 1 - PROPOSED CONSTRUCTION - 1 - SITE CONDITIONS - 2 - FIELD EXPLORATION - 2 - SUBSURFACE CONDITIONS - 2 - FOUNDATION BEARING CONDITIONS - 3 - DESIGN RECOMMENDATIONS - 3 - FOUNDATIONS - 3 - FLOOR SLABS -5- UNDERDRAIN SYSTEM - 5 - SURFACE DRAINAGE ... - 6 - LIMITATIONS - 6 - FIGURE 1 - LOCATION OF EXPLORATORY BORINGS FIGURE 2 - LOGS OF EXPLORATORY BORINGS FIGURE 3 - LEGEND AND NOTES FIGURES 4 - 5 - SWELL -CONSOLIDATION TEST RESULTS TABLE 1- SUMMARY OF LABORATORY TEST RESULTS H-P*KUMAR Project No. 18-7-231 PURPOSE AND SCOPE OF STUDY This report presents the results of a subsoil study for a proposed steel building to be located on Lot 5, Beaver Creek Highlands, County Road 317, southwest of Rifle, 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 Mike Rainey dated March 27, 2018. Potential geologic hazards that may impact the site are beyond the scope of this report. 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 building will be a 40 by 80 feet plan size steel frame and metal structure located in the southern part of the lot approximately as shown on Figure 1. Ground floor will be slab -on - grade. Grading for the structure is assumed to be relatively minor with cut depths between about 3 to 5 feet. We assume moderate foundation loadings, typical of the proposed type of construction and carried primarily by footing pads and connecting grade beams. 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. H-P%KUMAR Project No. 18-7-231 -2 - SITE CONDITIONS The lot was vacant and the ground surface in the area of the proposed building appeared mostly natural. Trees and brush in the building area had been removed and the vegetation consisted of grass and weeds. The terrain is relatively flat with a gentle slope down to the northeast. We did not observe any other buildings in the immediate area of Lot 5. FIELD EXPLORATION The field exploration for the project was conducted on April 5, 2018. Two exploratory borings were drilled at the locations shown on Figure 1 to evaluate the subsurface conditions. The borings were advanced with 4 -inch diameter continuous flight augers powered by a truck- mounted CME -45B 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 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 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 V2 to 1 foot of organic topsoil, consisted of sandy clay with basalt gravel and scattered cobbles and possible boulders. The sandy clay was occasionally very sandy, medium plastic and extended down to the maximum depth drilled of 26 feet. 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, presented on Figures 4 H-P%KUMAR Project No. 18-7-231 -3 - and 5, indicate low to moderate compressibility under conditions of loading and wetting. One sample (Boring 1 at 5') showed a moderate swell potential and two other samples (Boring 1 at 10' and Boring at 2.5') showed a nil to low swell potential when wetted under a constant 1,000 psf surcharge. The laboratory testing is summarized in Table 1. Free water was encountered in Boring 1 at a depth of about 131/2 feet at the time of drilling. No groundwater was encountered in Boring 2 at the time of drilling. The subsoils were generally moist with the exception of the Boring 1 at 5' sample that was slightly moist. FOUNDATION BEARING CONDITIONS The soils possess generally low bearing capacity and a nil to low swell potential. The moderate swell measured in the one sample that was slightly moist is believed to be an anomaly within the generally moist subsoils. The groundwater encountered in Boring 1 is likely a perched condition due to spring snow melt and run-off. Spread footings appear feasible for foundation support of the building with some risk of movement. The risk of movement is if potentially expansive bearing soils were to become wetted. We should review the exposed bearing soils at the time of excavation. Potentially expansive soils at footing (and floor slab) subgrade may need to be removed and replaced with compacted road base such as CDOT Class 2, 5 or 6 material. A lower risk of movement would be helical piers or screw piles. Provided below are recommendations for shallow spread footings. If recommendations for a deep foundation system are desired, we should be contacted. DESIGN RECOMMENDATIONS FOUNDATIONS Considering the subsurface conditions encountered in the exploratory borings and the nature of the proposed construction, we believe the building be founded with spread footings bearing on H-P%KUMAR Project No. 18-7-231 -4 - the natural soils with some risk of movement. Precautions, such as adequate compaction of foundation backfill and positive surface drainage away from the building foundation walls, should be taken to prevent wetting of the bearing soils. The design and construction criteria presented below should be observed for a spread footing foundation system. 1) Footings placed on the undisturbed natural granular 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 1 inch or less. There could be some additional movement if the bearing soils were to become wetted. The magnitude of the additional movement would depend on the bearing conditions and depth and extent of the wetting but may be on the order of 1 to 11/ inches. 2) The footings should have a minimum width of 16 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 such as by assuming an unsupported length of at least 12 feet. Foundation walls acting as retaining structures should also be designed to resist a lateral earth pressure corresponding to an equivalent fluid unit weight of at least 55 pcf. 5) All existing fill, topsoil, potentially expansive clay soils and any loose or disturbed soils should be removed and the footing bearing level extended down to the firm natural soils. The exposed soits in footing area should then be moistened and compacted. 6) A representative of the geotechnical engineer should observe all footing excavations prior to concrete placement to evaluate bearing conditions. H-Ptv'KUMAR Project No. 18-7-231 5 FLOOR SLABS The natural on-site soils, exclusive of topsoil, should be suitable to support lightly loaded slab - on -grade construction. There is a risk of slab movement if the subgrade were to become wetted. For long term performance of the slab, a depth (typically 11/2 to 2 feet) of imported road base such as CDOT Class 2, 5 or 6 base course, could be placed below the slab. We should review the slab subgrade conditions and need for a depth of compacted base course below the floor slab at the time of 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 sand and gravel road base should be placed immediately beneath the slab for support and to facilitate drainage. This material should consist of minus 2 inch aggregate with at least 50% retained on the No. 4 sieve and less than 12% passing the No. 200 sieve. All fill materials for support of floor slabs should be compacted to at least 95% of maximum standard Proctor density at a moisture content near to slightly above optimum. Required fill can consist of the on-site soils devoid of topsoil and oversized (plus 6 inch) rocks, or a well graded granular material such as road base can be imported. UNDERDRAIN SYSTEM It is our understanding the proposed finished floor elevation of the building at the lowest level is at or above the surrounding grade. Therefore, a foundation drain system is not required. It has been our experience in mountainous areas 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 and wall drain system. H-P*KUMAR Project No. 18-7-231 -6- Tf the finished floor elevation of the building is revised to have a floor level below the surrounding grade, we should be contacted to provide recommendations for an underdrain system. All earth retaining structures should be properly drained. SURFACE DRAINAGE Positive surface drainage is a very important aspect of the project to prevent wetting of the soils below the building. 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% 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 slope of 12 inches in the first 10 feet in unpaved areas and a minimum slope of 3 inches in the first 10 feet in paved areas. 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 10 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 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 H -P KIJMAJC Project No, 18-7-231 -7 - 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 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, _f? S• i.J David A. Young, P.L DAY/kacs'�i3b'ka�pp ggqq tt cc: Precision Buildings - Branden Tuell (btuell C precisionbuildings.net) c?'dif a aok "•��Ac�err 6 se 0 H-PkKUMAR Project No. 18-7-231 z 3 Y ROAD #317 L1'= PRiSCRIPTIVE� �S ,,1T -�h Gti 4+, rf�_,.-rl::�.. -.-c::^ ..;c;Sl3i•tt� ?5:_.__ .r�fuV.atC`affi.Y.TCNu . KL•15AL. ANT-) ALUM.LAI'--•' ,� L.S. NO. 10871 BEARS N48°08'19"E 27.98' cd Oma U [Wi�°ro M a�zz Lon ,Yccyy 4U 5 REBAR AND CAP 5 REBAR AND CAP L.S. NO. 37935 10.50' W.C. L.S. NO. 37935 20.65' W.C. iPOUNTY ROAD #317A 60' PRESCRIPTIVE EASEMENT ER FIELD LOCATION )UNTY ROAD #317A ;EMENT PER REC. NO. 773464 1AND CAP 35 35' W.C. ory� N syr 2634.10' LOT 5 35.185 AC. ± BEAVER CREEK HIGHLANDS PROPOSED BUILDING 3� 40' ACCESS & BORING 1 EASEMEISEE" BORING 2,- #5 REBAR CJD CAP \ 1 -20 '' L.S. NO. 37935 25' W.C. aRINEHART 1\' SPRING #8 00 UU min zc LOT 4 -- 35.242 AC, ± - 35.242AC.± 5 REBAR AND CAP ` L.S. NO. 37935 12' W.C. ly C24 C2 2 C G L23 C74 4-22 G21 L ti� 1 LOT 6 35.305 AC ± r s u9°5 6" 150 0 150 300 APPROXIMATE SCALE -FEET LtS L 1r�4` rn zz 00 H H W W rn � 33 zc 5 REB L.S. NO 1•,1 o ,� v, 2-05.66 f r r 30' UTILITY EASEMENT (TYP.) SEE NOTE #10 18-7-231 f H-P--14KUMAR LOCATION OF EXPLORATORY BORINGS I Fig. 1 -- 0 — 5 — 10 15 — 20 — 25 — 30 18-7-231 BORING 1 18/12 WC=17.7 DD=109 -200=77 50/6 WC=10.0 DD=120 38/12 WC=15.3 DD=115 21/12 WC=14.6 DD=115 9/12 59/12 H-P-� KUMAR BORING 2 f f 16 / =21.6 DWC/12 D=100 11/12 /- WC=15.8 DD=108 f / / /- 16/12 /- WC=17.2 // DD=114 f / /7 38/12 f WC=16.3 / • DD=109 -200=60 / / /- 24/12 0 5 10 15 20 25- 5- 30- 30- LOGS OF EXPLORATORY BORINGS 0 0 Fig. 2 ng'nrar n2 187231-02 lo 03 av0 LEGEND -'G / / / / li TOPSOIL; ORGANIC SILTY CLAY, FIRM, VERY MOIST, DARK BROWN. CLAY (CL); SANDY TO OCCASIONALLY VERY SANDY WITH BASALT GRAVEL AND SCATTERED COBBLES, STIFF TO VERY STIFF, TYPICALLY MOIST, BROWN AND GRAY -BROWN, MEDIUM PLASTICITY. RELATIVELY UNDISTURBED DRIVE SAMPLE; 2 -INCH I.D. CALIFORNIA LINER SAMPLE. DRIVE SAMPLE; STANDARD PENETRATION TEST (SPT), 1 3/8 INCH I.D. SPLIT SPOON SAMPLE, ASTM D-1586. 18/12 DRIVE SAMPLE BLOW COUNT. INDICATES THAT 18 BLOWS OF A 140 -POUND HAMMER FALLING 30 INCHES WERE REQUIRED TO DRIVE THE CALIFORNIA OR SPT SAMPLER 12 INCHES. Q DEPTH TO WATER LEVEL AT TIME OF DRILLING. NOTES 1. THE EXPLORATORY BORINGS WERE DRILLED ON APRIL 5, 2018 WITH A 4 -INCH DIAMETER CONTINUOUS FLIGHT POWER AUGER. 2. THE EXPLORATORY BORINGS WERE LOCATED BY THE CLIENT, APPROXIMATELY AS SHOWN ON FIGURE 1. 3. 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 LEVELS SHOWN ON THE LOGS WERE MEASURED AT THE TIME AND UNDER CONDITIONS INDICATED. NO GROUNDWATER ENCOUNTERED IN BORING 2. FLUCTUATIONS IN THE WATER LEVEL MAY OCCUR WITH TIME. 7. LABORATORY TEST RESULTS: WC = WATER CONTENT (%) (ASTM D 2216); DD = DRY DENSITY (pcf) (ASTM D 2216); -200= PERCENTAGE PASSING NO. 200 SIEVE (ASTM D 1140). 18-7-231 H-PtiKUMAR LEGEND AND NOTES Fig. 3 CONSOLIDATION - SWELL CONSOLIDATION - SWELL 2 1 0 —1 — 2 — 3 1 —1 — 2 3 10 APPLIED PRESSURE - KSF 10 1 100 SAMPLE OF: Sandy Clay with Gravel FROM: Boring 1 ® 10' WC = 15.3 %, DD = 115 pcf EXPANSION UNDER CONSTANT PRESSURE UPON WETTING • SAMPLE OF: Sandy Clay FROM: Boring 1 @ 5' WC = 10.0 %, DD = 120 pcf 1 _ I EXPANSION UNDER CONSTANT PRESSURE UPON WETTING Thee* test rct&ite appy anly to the ample* tatted T a testing apart hall not be reproduced, asaept in full, without the written approval of (Kumar and Associ tea, Inc. wall ,Consalidstion testi g perform d in .accordance with ASTM 0-45 6. i I 10 APPLIED PRESSURE - KSF 10 1 100 SAMPLE OF: Sandy Clay with Gravel FROM: Boring 1 ® 10' WC = 15.3 %, DD = 115 pcf EXPANSION UNDER CONSTANT PRESSURE UPON WETTING • 18-7-231 10 APPLIED PRESSURE - KSF H -P- KUMAR 10 100 SWELL -CONSOLIDATION TEST RESULTS Fig. 4 1 Thee* test rct&ite appy anly to the ample* tatted T a testing apart hall not be reproduced, asaept in full, without the written approval of (Kumar and Associ tea, Inc. wall ,Consalidstion testi g perform d in .accordance with ASTM 0-45 6. i I 18-7-231 10 APPLIED PRESSURE - KSF H -P- KUMAR 10 100 SWELL -CONSOLIDATION TEST RESULTS Fig. 4 CONSOLIDATION - SWELL CONSOLIDATION - SWELL 1 0 —1 — 2 3 — 4 0 — 1 — 2 — 3 —4 5 10 100 SAMPLE OF: Sandy Clay with Gravel FROM: Boring 2 @ 2.5' WC = 21.6 %, DD = 100 pcf N0 MOVEMENT WETTING UPON •-..- -�____ _� -----�.—..__.----•-- EXPANSION UNDERCONSTANT PRESSURE UPONPON WETTING i r These teat results apply only to the samples leaked. Tha tailing report shall not be repredvCea. eacepl in full, without the whiten *pirate! of Kumar and Associates, Inc Swell Cain+ hdolion lasting arformed in accordance wuI6 ASTM D-4546. ^--•� 10 100 APPLIED PRESSURE — KSF 10 100 18-7-231 H -P- KUMAR SWELL -CONSOLIDATION TEST RESULTS Fig. 5 SAMPLE OF: Sandy Clay with Gravel l FROM: Boring 2 @ 10' WC = 17.2 %, DD = 114 pcf N0 MOVEMENT WETTING UPON •-..- -�____ _� -----�.—..__.----•-- i r These teat results apply only to the samples leaked. Tha tailing report shall not be repredvCea. eacepl in full, without the whiten *pirate! of Kumar and Associates, Inc Swell Cain+ hdolion lasting arformed in accordance wuI6 ASTM D-4546. ^--•� APPLIED PRESSURE — KSF 10 100 18-7-231 H -P- KUMAR SWELL -CONSOLIDATION TEST RESULTS Fig. 5 1P)t- VUAR TABLE 1 SUMMARY OF LABORATORY TEST RESULTS SAMPLE LOCATION BORING 1 DEPTH (ft) NATURAL MOISTURE CONTENT (%) NATURAL DRY DENSITY (pcf) 21 17.7 109 5 10.0 120 GRADATION GRAVEL (%) SAND (%) PERCENT PASSING NO. 200 SIEVE 77 ATTERBERG LIMITS UNCONFINED COMPRESSIVE STRENGTH LIQUID LIMIT (%) PLASTIC INDEX (%) (psf) Project No. 18-7-231 SOIL TYPE Sandy Clay with Gravel Sandy Clay 10 15.3 115 15 14.6 115 Sandy Clay with Gravel Sandy Clay with Gravel 2 Sandy Clay with Gravel 5 15.8 108 10 17.2 114 15 16.3 109 60 Sandy Clay with Gravel Sandy Clay with Gravel J Very Sandy Clay