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Home My WebLink About11.02 Subsoil Study Parcel DH-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 Summit County, Colorado SUBSOIL STUDY FOR FOUNDATION DESIGN PROPOSED RESIDENCE PARCEL D, WILDE MINOR SUBDIVISION COUNTY ROAD 251 GARFIELD COUNTY, COLORADO PROJECT NO. 17-7-128 APRIL 14, 2017 PREPARED FOR: BILL WILDE 353 COUNTY ROAD 351 RIFLE, COLORADO 81650 bill.wilde.363 @ gmail.com j TABLE OF CONTENTS PURPOSE AND SCOPE OF STUDY - 1 - PROPOSED CONSTRUCTION - 1 - SITE CONDITIONS - 1 - FIELD EXPLORATION - 2 - SUBSURFACE CONDITIONS - 2 - DESIGN RECOMMENDATIONS - 3 - FOUNDATIONS - 3 - FLOOR SLABS - 4 - UNDERDRAIN SYSTEM - 4 - SURFACE DRAINAGE - 5 - LIMITATIONS - 5 - FIGURE 1 - LOCATION OF EXPLORATORY BORING FIGURE 2 - LOG OF EXPLORATORY BORING FIGURES 3 and 4 - SWELL -CONSOLIDATION TEST RESULTS TABLE 1- SUMMARY OF LABORATORY TEST RESULTS H-P-KUMAR Project No. 17-7-128 PURPOSE AND SCOPE OF STUDY This report presents the results of a subsoil study for a proposed residence to be located on Parcel D, Wilde Minor Subdivision, County Road 251, 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 proposal for geotechnical engineering services to you dated January 12, 2017. 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 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 2,500 square foot residence will be one and two story wood frame construction above a crawlspace and with an attached garage. Grading for [he 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, 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 property is vacant irrigated horse pasture vegetated with grass and weeds. The ground surface is relatively flat with a slight slope down to the southwest. H-PKUMAR Project No. 17-7-128 -2 - FIELD EXPLORATION The field exploration for the project was conducted on March 31, 2017. One exploratory boring was drilled at the 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 - 45B drill rig. The boring was logged by a representative of H-P/Kumar. 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 Log of Exploratory Boring, 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 below about one foot of topsoil consist of stratified sandy clay and clayey sand down to the bottom of the boring at 31 feet. Laboratory testing performed on samples obtained from the borings included natural moisture content, density and finer than sand size gradation analyses. Results of swell -consolidation testing performed on relatively undisturbed drive samples, presented on Figures 3 and 4, indicate low to moderate compressibility under conditions of loading and wetting. The laboratory testing is summarized in Table 1. Water seepage was encountered at about 13 feet in the boring at the time of drilling and the boring caved at 6 feet following drilling. The subsoils were moist. H -P # KUMAR Project No. 17-7-128 -3 - 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 granular 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 1,200 psf. Based on experience, we expect settlement of footings designed and constructed as discussed in this section will be about I inch or less. 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 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. 5) All existing fill, topsoil and any loose or disturbed soils should be removed and the footing bearing level extended down to the relatively undisturbed soils. The exposed soils in footing area should then be moistened and compacted. If water seepage is encountered, the footing areas should be dewatered before concrete placement. 6) A representative of the geotechnical engineer should observe all footing excavations prior to concrete placement to evaluate bearing conditions. H -P- KUMAR Project No. 17-7-128 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 free - draining gravel should be placed beneath slabs 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 2% 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 optimum. Required fill can consist of the on- site granular soils devoid of vegetation and topsoil. UNDERDRAIN SYSTEM Although free water was not encountered during our exploration, 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 create a perched condition. We recommend below -grade construction, such as retaining walls and deep crawlspace areas, be protected from wetting and hydrostatic pressure buildup by an underdrain system. A shallow crawlspace or slab -on -grade should not require an underdrain provided that good surface drainage is maintained around the building exterior. If installed, 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 I% to a suitable gravity outlet or sump and pump. Free -draining granular material used in the underdrain system should contain less than 2% passing the No. 200 sieve, H-1)-4. KUMAR Project No. 17-7-128 -5 - less than 50% passing the No. 4 sieve and have a maximum size of 2 inches. The drain gravel backfill should be at least 11/2 feet deep. SURFACE DRAINAGE The following drainage precautions should be observed during construction and maintained at all times after the residence 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 b inches in the first 10 feet in unpaved areas and a minimum slope of 3 inches in the first 10 feet in paved areas. Free -draining wall backfill should be 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. 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 interpolation and extrapolation of the subsurface conditions identified at the exploratory boring and variations in the subsurface FI -Pk KUMAR Project No. 17-7-128 -6 - 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, Louis Eller Reviewed by: Daniel E. Hardin, P. LEE/kac H -P KUMAR Project No. 17-7-128 PARCEL D BORING 1 • IMO OS 75 0 75 150 APPROXIMATE SCALE -FEET EXISTING SHOP/BARN IRRIGATION DITCH PARCEL C COUNTY ROAD 251 (N. HASSE LANE) EXISTING RESIDENCE 17-7-128 H -P- KUMAR LOCATION OF EXPLORATORY BORING Fig. 1 --O 5 -- 1 0 15 r--- 20 25 30 — 3 5 BORING 1 EL. 559 6' 8/12 WC=17.3 DD=108 _ LEGEND__ w TOPSOIL; ORGAN C SANDY CLAY AND SILT, FIRM, MOIST, DARK BROWN. SAND AND CLAY (SC—CL); STRATIFIED SANDY CLAY AND CLAYEY SAND, SILTY, SOFT TO STIFF, MOIST, BROWN. DR VE SAMPLE, 2—INCH 1.0. CALIFORNIA LINER SAMPLE. 13/12 WC=13.4 DD=108 8/12 DRIVE SAMPLE BLOW COUNT. INDICATES THAT 8 BLOWS OF A 140—POUND —200=38 HAMMER FALLING 30 INCHES WERE REQUIRED TO DRIVE THE SAMPLER 12 INCHES. 7/12 WC=15.6 D0=108 4/12 WC=29.6 OD=92 —200=91 9/12 10/12 21/12 — ► DEPTH AT WHICH BORING CAVED. --► WATER SEEPAGE NOTED AT 13 FEET DEPTH. __NOTES 1. THE EXPLORATORY BORING WAS DRILLED ON MARCH 31, 2017 WITH A 4—INCH DIAMETER CONTINUOUS FLIGHT POWER AUGER. 2. THE LOCATION OF THE EXPLORATORY BORING WAS MEASURED APPROXIMATELY BY PACING FROM FEATURES SHOWN ON THE SITE PLAN PROVIDED. 3. THE ELEVATION OF THE EXPLORATORY BORING WAS OBTAINED BY INTERPOLATION BETWEEN CONTOURS ON THE SITE PLAN PROVIDED. 4. THE EXPLORATORY BORING LOCATION AND ELEVATION SHOULD BE CONS DERED ACCURATE ONLY TO THE DEGREE IMPLIED BY THE METHOD USED. 5. THE LINES BETWEEN MATERIALS SHOWN ON THE EXPLORATORY BORING LOG REPRESENT THE APPROX.MATE BOUNDARIES BETWEEN MATERIAL TYPES AND THE TRANSITIONS MAY BE GRADUAL. 6. GROUNDWATER WAS NOT ENCOUNTERED IN THE BORING AT THE TIME OF DRILLING. 7. LABORATORY TEST RESLLT5_ WC = WATER CONTENT (X) (ASTM D 2216); DD = DRY DENSITY (pct) (ASTM D 2216); —200 = PERCENTAGE PASSING NO. 200 SIEVE (ASTM D 1140). 17-7-128 H-P1KUMAR LOG OF EXPLORATORY BORING Fig. 2 2 .. 0 —1 — 2 — 3 — 4 CONSOLIDATION - SWELL. SAMPLE OF: Sandy Silty Clay FROM: Boring 1 0 2.5' WC = 17.3 %, DD = 108 pcf Then test none appy only to he .Menet 6o reeprotenet odduc exctooting ept M..%aA the written approval of Kumar and Anadetos. Inc. Sorer Cncnrdntan ginned In amardent. wi AS i DD-r'J.6. NO MOVEMENT UPON WETTING 1.0 APPLIED PRESSURE - KSF 10 100 17-7-128 H -P KUMAR SWELL -CONSOLIDATION TEST RESULT Fig. 3 CONSOLIDATION - SWELL 2 —1 — 2 — 3 — 4 — 5 — 6 SAMPLE OF: Sandy SIUy Clay FROM: Boring 1 ® 10' WC = 15.6 7, DD = 108 pcf ADDITIONAL COMPRESSION UNDER CONSTANT PRESSURE DUE TO WETTING »,.w t..t results owwb rnr le M. ..not.{ titled. in. t..tfnq ,.rrt .nm net b. mwr.duc.d, s.c.pt In full, without tle *Mho swerve of rumor and A..ockt.., Inc Swd Imemlone. w."dntlen t.•14q awl"m.d0-4641. In arcadJSN 1.0 APPLIED PRESSURE - KSF IU • 160 H-PvKUMAR SWELL—CONSOLIDATION TEST RESULT Fig. 4 H-P1<UMAR it J CD Q 1— SUMMARY OF LABORATORY TEST RESULTS Project No. 17-7-128 SOIL TYPE Sandy Silty Clay Silty Clayey Sand Sandy Silty Clay 11 I Slightly Sandy Silty Clay 11 UNCONFINED COMPRESSIVE STRENGTH (PSF) I ATTERBERG LIMITS u x 2 - o. — i J 0 J PERCENT PASSING NO. 200 SIEVE co M -1 01 Z 0 rz a 0 g I7 0 z am a a ccN NATURAL DRY DENSITY (pcf) 108 108 108 0\ . NATURAL MOISTURE CONTENT (%) C*1 N .-! M .--1 tiD In .--4 VD 01 N 11 SAMPLE LOCATION DEPTH (ft) N -- Si oz 2 0 CD --,