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Home My WebLink AboutSoils Report 07.29.2016H-PKUMAR 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 Parker, Glenwood Springs, and Silverthome, Colorado SUBSOIL STUDY FOR FOUNDATION DESIGN PROPOSED SHARP RESIDENCE PARCEL H, CEDAR SPRINGS RANCH 693 NORTH CEDAR SPRINGS RANCH ROAD GARFIELD COUNTY, COLORADO PROJECT NO. 16-7-129 JULY 29, 2016 PREPARED FOR: DOOLEN CONSTRUCTION ATTN: DAVE DOOLEN 3838 COUNTY ROAD 243 NEW CASTLE, COLORADO 81647 dave@doolanconstruction.com 1iv . ' 4/7/16, from \etil t k1 1 ? S 6M 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 - SURFACE DRAINAGE - 4 - LIMITATIONS - 5 - FIGURE 1 - LOCATION OF EXPLORATORY BORING FIGURE 2 - LOG OF EXPLORATORY BORING FIGURE 3 - LEGEND AND NOTES FIGURE 4 - SWELL -CONSOLIDATION TEST RESULTS FIGURE 5 - GRADATION TEST RESULTS TABLE 1- SUMMARY OF LABORATORY TEST RESULTS PURPOSE AND SCOPE OF STUDY This report presents the results of a subsoil study for the proposed Sharp residence to be located on Parcel H, Cedar Springs Ranch, 693 North Cedar Springs Ranch Road, 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 general accordance with Hepworth-Pawlak Geotechnical (now H-P/Kumar) agreement for geotechnical engineering services to Doolen Construction dated June 21, 2016. One boring was drilled for the study as requested by the client. A field exploration program consisting of an exploratory boring was conducted to obtain information on the general 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 residence will be located north of the existing barn on the site as shown on Figure 1. The building will be a single story wood frame structure over crawlspace. Grading for the structure is assumed to be relatively minor with cut depths between about 3 to 4 feet. We assume relatively light foundation loadings, typical of the proposed type of construction. If building loadings, Iocation or grading plans change significantly from those described above, we should be notified to re-evaluate the recommendations contained in this report. 11 -Pt KUMAR SITE CONDITIONS The lot was occupied by a barn, located as shown on Figure 1, at the time of our field exploration. The site of the proposed residence was vacant with vegetation consisting of grass, sagebrush and juniper trees. The terrain was gently sloping down to the east with an elevation difference of about one foot across the building site. There were basalt boulders up to about 3 feet in diameter stockpiled near the building site, apparently from a previous nearby excavation. FIELD EXPLORATION The field exploration for the project was conducted on June 29, 2016. One exploratory boring was drilled at the approximate locution 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 -45B drill rig. The boring was logged by a representative of HP/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 art 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 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 are shown on Figure 2. The subsoils encountered, below about 1 foot of organic topsoil, consisted of about 31/2 H-P%KUMAR -3 - feet of stiff, very sandy clay and silt overlying relatively dense, silty sandy basalt gravel and cobbles with probable boulders, that extended down to the depth drilled of 13 feet. Drilling in the dense coarse granular soils with auger equipment was difficult due to the cobbles and probable boulders and drilling refusal was encountered in the deposit. Laboratory testing performed on samples obtained from the borings included natural moisture content and density, and gradation analyses. Results of swell -consolidation testing performed on a relatively undisturbed drive sample of the very sandy clay and silt soils, presented on Figure 4, indicate moderate compressibility under conditions of loading and wetting with a low hydro -compression potential. Results of gradation analyses performed on a small diameter drive sample (minus 11/2 inch fraction) of the coarse granular subsoils are shown on Figure 5. The Iaboratory testing is summarized in Table 1. No free water was encountered in the boring at the time of drilling and the subsoils were moist to slightly moist with depth. FOUNDATION BEARING CONDITIONS At assumed excavation depths, we expect the clay and silt soils will be exposed at subgrade. These soils have low bearing capacity and generally moderate settlement potential, especially when wetted. Spread footings bearing on these soils can be used for foundation support of the building with some risk of settlement. Placing the footings entirely on the underlying dense coarse granular soils would provide a relatively low risk of foundation settlement. 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 H -Pk KUMAR -4 - footings bearing on the natural soils with some risk of settlement. Precautions should be taken to prevent wetting of the fine grained 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 soils should be designed for an allowable bearing pressure of 1,500 psf. Based on experience, we expect settlement of footings designed and constructed as discussed in this section will be up to about I inch. There could be some additional settlement if the bearing soils were to become wetted. 2) The footings should have a minimum width of 18 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 50 pcf. The foundation backfill should not contain topsoil or oversized (plus 6 inch) rocks. 5) All existing fill, topsoil and any loose disturbed soils should be removed, and the subgrade moistened and compacted. 6) A representative of the geotechnical engineer should observe all footing excavations prior to concrete placement to evaluate bearing conditions. SURFACE DRAINAGE A perimeter foundation drain around the shallow crawlspace (less than 4 feet deep) may not be needed provided there is adequate compaction of the foundation backfill and a H -P t KUMAR -5 - positive surface slope maintained away from the foundation walls. The following drainage precautions should be observed during construction and maintained at all times after the residence has been completed: I) 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 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 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 extrapolation of the subsurface conditions identified at H -P KUMAR - b - 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 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, H-Pk-KUMAR Shane M. Mello, Staff Engineer Reviewed by re $ ( David A. Young, P di 2 32-216 I 1:1 CO: = SMMlksw PARCEL G PARCEL H SW1/4NE1/4 SECTION 11 pCCEs ENT APPROXIMATE SCALE 1'=300' 11 BORING 1 O EXISTING BARN PROPOSED RES'.DENCE WA TERVNE SFAA rr NW1/4NE1/4 SECTION 11 16-7-129 H --P %- KU MAR LOCATION OF EXPLORATORY BORING Figure 1 BOR NG 1 T 17/12 WC= 202 DD=77 -200-54 71/12 WC=6 5 DD= 124 40/6.50/5 WC=4.1 +4 39 -200 32 S 10 _ 15 15 NOTE Explanation 01 symbols is shown on Figure 3 m 0 16-7-129 H -P- KUMAR EP:. rxc+ ny j C',7 rrc: cru C.7ch LLte.14% 4.1tny 1 E., weU LOG OF EXPLORATORY BORING Figure 2 LEGEND. ® TOPSOIL; organic clayey sandy silt with gravel, medium stiff, moist, dark reddish brown CLAY AND SILT (CL -ML), very sandy, stiff, moist light reddish brown calcareous. BASALT GRAVEL AND COBBLES (GM), sandy, silty, boulders probable dense, slightly moist to moist, yellow-brown with black rocks Relatively undisturbed drive sample, 2 -inch I D California liner sample I/ Drive sample; standard penetration test (SPT), 1 3/8 inch I.D. split spoon sample, ASTM -1586 Drive sample blow count, indicates that 17 blows of a 140 pound hammer tailing 30 inches were required to drive the California or SPT sampler 12 inches Practical drilling refusal Where shown above bottom of tog, indicates that multiple attempts were made to advance the baring L 17/12 T NOTES 1. The exploratory boring was drilled on June 29, 2016 with a 4 -inch diameter cont nuous flight power auger 2. The exploratory boring location was measured approximately by pacing from features shown on the site plan provided. 3 The exploratory boring elevation was not measured and the log of exploratory boring is drawn to depth 4. 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 between material types and transitions may be gradual 6. No free water was encountered in the boring at the tame of drilling Fluctuat.on in water level may occur with time 7. Laboratory Testing Results WC = Water Content (%) DD = Dry Density (pcf) +4 = Percent retained on the No 4 sieve -200 = Percent passing No 200 sieve 16-7-129 H-P� KUMAR LEGEND AND NOTES Figure 3 1 0 e 1 0 (A m 2 E 0 3 4 Moisture Content = 20,2 percent Dry Density = 77 pcf Sample of Very Sandy Clay and Silt From Baring 1 at 2112 Feet °N\\\,D _Compression upon welting 01 10 APPLIED PRESSURE - ksf 10 100 16-7-129 H-Pt-KUMAR SWELL -CONSOLIDATION TEST RESULTS Figure 4 aallai iI4CRfes HYDROMETER ANALYSIS }1q TIME READINGS U S STANDARD SERIES 20.45 I 15 MINIIN 60MINi9MIN 4 M N 1 MIN #200 #100 #50 #30 #16 06 SIEVE AN1 ALYSIS I CLEAR SQUARE OPEN NGS if 4 3/8' 314' 1 12' 3' 5' 6' 8 10C 10 20 30 43 50 60 70 80 90 100 a—aaa—PISI Sad SI i rrrr.rr r. a11111111rr aa� a— aaww aaa_ r✓r. aaaaar aaaa aaaa-aaaaaaa aara i aa_ SI SIM ar.rr aaaaae >.� all St Sal a _ arar rsaa 1 it a a— — r as 11•111allS Sas IM SI as w_ _ra ri 11. r1 r1 _ a••••1111aaaaa1�a ra w_wa..a raaar rrrri aSE iri _ r: r SI MI aalllla rr— as iaaw n1aaara wrM aaaaarr •i — ••••• aa_ w i w_ aaa i SI w_' i a i a—aaaraa111a aaa SI it MS 11a s a aaaa� a—rte a arrl a a a ar___a IS aa_ Nanarasa aa wr SI aaaami a i S aa_ awla al ra_ S Si rasr—ran!aa aaP SS Si a— a� a SI MaSa aawllrala a/ S _ law —r SI r 1 _ anal l aaaaaC aar IN ran 1MIr raar! 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MS a_ a naw St IN SI •mai raalr_raaaal!_ S aaaa a— lir arm a SI S aaa SSIISI SI Illi,S w_i��aalai a_aa_raaar�� i aaw.aar cent i SI iaaw as a aw w1a alt Ms — w_rr.rr_r_ai —a MSNS_r— it a_ iri • SAM a.S aaaI,r SallS .— aaaaFlYwiSISaas 1 a1 cera_ racer S11•111 aaaaaaa arae—SS= a1 SI MIS Si a— aces aaaaaaaa PSI a—aaai arae: a—aaaaaaaaa[ 111111�aaaa—aaaa aallaa aaara_ as ra_ raaaa! tar aaaa�a�aa.ra tar a—Ylr♦—aa� alalaraan rrraraar arm race! �_ cent aaa—aalaal waaaaw SP= OEM= as r tar -- wa•agPIY1rw11a as SI ri -- !_ —» i w_r— aS _ a aaaa i L11a4YY tar r aaaa aa! al aaaa !_ri slwS SIM =IS a_ r race a_a_r_ri a r! a_arr_ Sias 001 002 005 009 019 037 074 150 a rlrr ^! al SI a al aaaa a as ri r as aall r race. • ri r awns tart mama sarl�raaaal s as al lana. as as ralr r+wwrrasa 300 600 1 15 2.36 4 75 9.5 19 0 37 5 76 2 152 203 12 5 127 DIAMETER OF PARTICLES IN MILLIMETERS COBBLES 0 % FCC GRAVEL 39 % SAMPLE OF Silty Sandy Gravel sugt YI EAM 1 1 WARY SAND 29 % SiLT AND CLAY 32 % FROM Boring 1 al 10 Feel Fll 70 r'LI Sul 2.l 1r: 0 16-7-129 KUMAR 1 r 1 GRADATION TEST RESULTS Figure 5 Job No. 16-7-129 SOIL OR BEDROCK TYPE Sandy Silty Clay Gravelly Sandy Clay Sandy Very Silty Gravel UNCONFINED COMPRESSIVE STRENGTH (PSF) th 2 J IZ w 0 S 414 (1 o a 5 z 0. LIQUID UMIT PERCENT PASSING NO.200 SIEVE 54 CN en z p F� d cc 0 0 a a N Cs GRAVEL (%) ON P+7 NATURAL DRY p DENSITY nci n NATURAL MOISTURE CONTENT (vj cit rst ,,.) II SAMPLE LOCATION ia BORING