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HomeMy WebLinkAboutSoils Report 02.26.20181rCTLITHOMPSON 1 k e a a■ o a A T■ s RECEIVED MAR U 9 2018 GARFIELD COUNTY Cow 1NM' DEVELOPMENT SOILS AND FOUNDATION INVESTIGATION McDANIEL RESIDENCE ADDITION 1000 COUNTY ROAD 323 GARFIELD COUNTY, COLORADO Prepared For: ALICE McDANIEL 1000 County Road 323 Rifle, CO 81650 Project No. GS06206.000-120 February 26, 2018 TABLE OF CONTENTS SCOPE - 1 S(JMMARY OF CONCLUSIONS ' 1 SITE CONDITIONS ' ' ' ' PROPOSED CONSTRUCTION 2 ' SUBSURFACE CONDITIONS 2 EARTHWORK_~_. - .� 3 Structural Fill 4 Foundation Backfill ' ` 4 FOUNDATION ` '-' 5 Footings� - '- FLOOR SLAB 6 CONSTRUCTION '' ' 7 ' SURFACE DRAINAGE ~°"^-~T CONCRETE ' 8 GEOTECHNICAL RISK . . 9 LIMITATIONS ` ' 9 FIGURE 1 - VICINITY MAP FIGURE 2 - LOCATION OF EXPLORATORY PITS FIGURE 3- SUMMARY LOG OF EXPLORATORY PITS FIGURE 4 - SWELL -CONSOLIDATION TEST RESULTS FIGURE 5 - GRADATION TEST RESULTS TABLE 1 - SUMMARY OF LABORATORY TESTING ALICE MCDAw/EL MCDANIEL RESIDENCE ADDITION PROJECT NO. onomommo-1zo SCOPE This report presents the results of our soils and foundation investigation for the McDaniel Residence Addition proposed at 1000 County Road 323 in Gar- ficld County, Colorado, A vicinity map with the location of the site is shown on Figure 1. We conducted this investigation to evaluate subsurface conditions at the site and provide geotechnical engineering recommendations for the planned construction. Our report was prepared from data developed from our field explo- ration, laboratory testing, engineering analysis, and our experience with similar conditions. This report includes a description of the subsurface conditions ob- served in our exploratory pits and presents geotechnical engineering recommen- dations for design and construction of the addition foundation and floor system, as well as details influenced by the subsoils. A summary of our conclusions is presented below. SUMMARY OF CONCLUSIONS 1. Subsoils encountered in our exploratory pits consisted of about 1 foot of topsoil and 2 to 4.5 feet of natural sandy clay underlain by clayey sand and gravel with cobbles and boulders to the maximum depth excavated of 8 feet. Groundwater was not found in the pits at the time of excavation. We recommend constructing the addition on footing foundations supported by the undisturbed, clayey sand and gravel soil. A level- ing course of granular structural fill will likely be required below foot- ings. We recommend removal of about 18 inches of the soils below the addition floor slab and replacement with granular structural fill. 4. The ground surface should be graded to provide for rapid removal of surface water away from the residence and addition. ALICE MCDANIEL MCDANIEL RESIDENCE ADDITION PROJECT NO. GS06206.000-120 C;lUserslalhateleox1ProjeclslGlenwood Springs - Projects1GS06206.000112012. RepOrlssGS06206.000120 Rl.docx 1 SITE CONDITIONS The McDaniel property is located about 3/4 mile south of the 1-70 Rulison Exit and the Colorado River. Residences, hayfields and grazing lands are adja- cent to the subject property. An existing wood -framed residence is on the prop- erty. Several smaller structures and sparse grass are to the east of the resi- dence. Ground on the property slopes from east to west at 5 percent or less. Mature trees and landscaping are adjacent to the buildings. PROPOSED CONSTRUCTION The addition will be one-story, wood -framed structure with a slab -on -grade floor. No below -grade areas are planned. We anticipate foundation Toads along perimeter walls of Tess than 1,500 pounds per linear feet. Maximum interior col- umn loads of about 20 kips are expected. Excavation depths of 3 to 5 feet are likely to be required to expose the clayey sand and gravel soil below the building. We should be provided building plans as they are developed, so that we can pro- vide geotechnical engineering input and check that our recommendations and design criteria are appropriate. SUBSURFACE CONDITIONS Subsurface conditions at the site were investigated by observing the exca- vation of two exploratory pits at the approximate location shown on Figure 2. Subsurface conditions were logged by our representative who obtained samples of the soils during excavation operations. Subsoils encountered consisted of 1 foot of sandy clay topsoil with organic matter and 2 to 3.5 feet of natural sandy ALICE MCDANIEL MCDANIEL RESIDENCE ADDITION PROJECT NO, GS06206.000-120 C:tUserslathatelBox\Projects\Glenwood Springs - Projects1GS06206.000t12012. Reports1GS06206.000 120 Rl.docx 2 clay underlain by clayey sand and gravel with cobbles and boulders to the maxi- mum depth excavated of 8 feet. Groundwater was not found in our pits at the time of excavation. The pits were backfilled immediately after excavation. Graphic logs of the soils observed in our exploratory pits are shown on Figure 3. Samples of the soils obtained in the field were returned to our laboratory where field classifications were checked and typical samples selected for perti- nent engineering testing. A swell -consolidation test performed on a sample of sandy clay indicated 0.4 percent consolidation due to wetting under a load of 1,000 psf and more than 9 percent when the load was increased to 5,000 psf. Gradation testing on two samples of clayey sand determined 21 and 30 percent gravel, 39 and 45 percent sand, and 31 and 34 percent silt and clay (passing the No. 200 sieve). Swell -consolidation test results and gradation test results are shown on Figures 4 and 5, respectively. Laboratory test results are summarized in Table I. EARTHWORK We anticipate excavation depths of 3 to 5 feet will be required to penetrate clay soils and expose the clayey sand and gravel soil. Excavations at this site can be accomplished with equipment such as a medium size backhoe. Sides of excavations need to be sloped to meet local, state and federal safety regulations. The clay soil will likely classify as Type B soils based on OSHA standards gov- erning excavations. Temporary slopes deeper than 4 feet that are not retained should be no steeper than 1 to 1 (horizontal to vertical) in Type B soils. The clayey sand and gravel will likely classify as Type C soils which require excava- tion sides no steeper than 1.5 horizontal to 1 vertical. ALICE MCDANIEL MCDANIEL RESIDENCE ADDITION PROJECT NO, GS06206.000-120 C:\UserslathatelBoxlProjects\Glenwood Springs -ProjectslGS06206,000\12012. Reporls\GS00206.000120 R1.docx 3 Free groundwater was not encountered in our exploratory pits during ex- cavation operations. We do not anticipate the groundwater will be encountered in excavations for the planned construction. Structural Fill The clayey sand and gravel soil contains a significant percentage of cob- bles and boulders that could result in a rough surface at planned footing eleva- tions. A leveling course of granular structural fill may be required below footings. Additionally, we recommend removal of an 18 -inch thickness of soils from below the addition floor slab and replacement with granular structural fill. We recommend that structural fill consist of a CDOT Class 6 aggregate base course or similar soil. Structural fill should be placed in loose lifts of 8 inches thick or Tess, moisture -conditioned to within 2 percent of optimum mois- ture content, and compacted to near 100 percent of ASTM D 698 maximum dry density. Moisture content and density of structural fill should be checked by a representative of our firm during placement. Observation of the compaction pro- cedure is necessary. Testing without observation can lead to undesirable perfor- mance. Foundation Backfill Proper placement and compaction of foundation backfill is important to re- duce infiltration of surface water and settlement of backfill. The natural soils can be used as backfill, provided they are free of rocks larger than 3 -inches in diame- ter, organics, and debris. Backfill should be placed in loose lifts of approximately 10 inches thick or less, moisture conditioned to within 2 percent of optimum mois- ture content, and compacted. The backfill should be compacted to at least 95 ALICE MCDANIEL MCDANIEL RESIDENCE ADDITION PROJECT NO. GS06206.000-120 C:\UsershathatelBox\Projects\Glenwood Spring$ - ProjectslGS06206.000112012. Reports1GS06206.000 120 R1.docx 4 percent of maximum standard Proctor dry density (ASTM D 698). Moisture con- tent and density of the backfill should be checked during placement by a repre- sentative of our firm. FOUNDATION We recommend constructing the addition on footing foundations sup- ported by the natural, clayey sand and gravel soils. A leveling course of densely - compacted, granular structural fill could be required below footings. The struc- tural fill should be in accordance with the recommendations in the Structural Fill section. It is important that our representative be called to observe conditions ex- posed in the completed foundation excavation to confirm that the exposed soils are as anticipated and suitable for the designed foundation. Design and con- struction criteria for footings are below. Footings 1. The addition can be constructed on footing foundations supported by the natural clayey sand and gravel soils. A leveling course of granular structural fill could be required below footings. 2. Footings on the natural clayey sand and gravel soils can be sized using a maximum allowable bearing pressure of 3,000 psf. 4. Continuous wall footings should have a minimum width of 16 inches. Foundations for isolated columns should have minimum di- mensions of 24 inches by 24 inches. Larger sizes may be required, depending upon foundation loads. 5. Grade beams and foundation walls should be well reinforced, top and bottom, to span undisclosed loose or soft soil pockets. We rec- ommend reinforcement sufficient to span an unsupported distance of at least 12 feet. Reinforcement should be designed by the struc- tural engineer. ALICE MCDANIEL MCDANIEL RESIDENCE ADDITION PROJECT NO. GS06206.000-120 C:hUsers1athatelBox1Projects1Glenwood Springs - Projects \GS06206.000h120\2. Reports\GS06206.000120 R1.dosx 5 The soils under exterior footings should be protected from freezing. We recommend the bottom of footings be constructed at a depth of at least 36 inches below finished exterior grades. FLOOR SLAB The natural clayey sand and gravel soil is likely 3 to 4 feet below existing ground surface at the site. We recommend removal of an 18 -inch thickness of the soils below the addition floor slab and replacement with densely -compacted, granular structural fill. We expect risk of differential movement will be low for floor slabs supported on the structural fill, provided the structural fill is in accord- ance with recommendations from the Structural Fill section. We recommend the following precautions for slab -on -grade construction at this site. These precautions will not prevent movement from occurring; they tend to reduce damage if slab movement occurs. 1. Slabs should be separated from exterior walls and interior bearing members with slip joints which allow free vertical movement of the slabs. 2. The use of underslab plumbing should be minimized. Underslab plumbing should be pressure tested for leaks before the slabs are constructed. Plumbing and utilities which pass through slabs should be isolated from the slabs with sleeves and provided with flexible couplings to slab supported appliances. 3. Exterior patio and porch slabs should be isolated from the building foundation walls. These slabs should be well -reinforced to function as independent units. Movements of these slabs should not be transmitted to the building. Frequent control joints should be provided, in accordance with American Concrete Institute (ACI) recommendations, to reduce problems associated with shrinkage and curling. ALICE MCDANIEL MCDANIEL RESIDENCE ADDITION PROJECT NO. OS06206.000-120 C:\Userslathate\Box\Projects\Glenwood Springs - Projects YGS06206.0001120l2. Reports 1GS06206.000 120 R1.docx 6 BELOW -GRADE CONSTRUCTION Foundation walls which extend below -grade should be designed for lateral earth pressures where backfill is not present to about the same extent on both sides of the wall, such as where below -grade areas are constructed. Subsurface drains are also required for below -grade areas. We understand that no below - grade construction, such as a basement or crawl space, is planned for the addi- tion. If plans change to include a basement or crawl space, we should be con- tacted to provide recommendations for design lateral earth pressure and a drain system subsurface. SURFACE DRAINAGE Surface drainage is critical to the performance of foundations, floor slabs, and concrete flatwork and should be designed to provide rapid runoff of surface water away from the residence. Proper surface drainage and irrigation practices can help control the amount of surface water that penetrates to foundation levels and contributes to settlement. Positive drainage away from the foundation and avoidance of irrigation near the foundation also help to avoid excessive wetting of backfill soils, which can lead to increased backfill settlement and possibly to higher lateral earth pressures, due to increased weight and reduced strength of the backfill. CTL (Thompson, Inc. recommends the following precautions. 1. Wetting or drying of the open foundation excavations should be avoided. 2. The ground surface surrounding the exterior of the residence should be sloped to drain away from the building in all directions. We recommend a minimum constructed slope of at least 12 inches ALICE MCDANIEL MCDANIEL RESIDENCE ADDITION PROJECT NO. GS06206.000-120 C;1Userslathate\Box\Projects\GIenwood Springs - Projects1GS06206.000112012. Reports\GS06206.000120 R1.docx 7 in the first 10 feet (10 percent) in landscaped areas around the resi- dence. Roof downspouts and drains should discharge well beyond the lim- its of all backfill. Splash blocks and/or extensions should be pro- vided at all downspouts so water discharges onto the ground be- yond the backfill. We generally recommend against burial of down- spout discharge. 4. Irrigation should be limited to the minimum amount sufficient to maintain vegetation; application of more water will increase likeli- hood of slab and foundation movements. Plants placed close to foundation walls should be limited to those with low moisture re- quirements. Irrigated grass should not be located within 5 feet of the foundation. Sprinklers should not discharge within 5 feet of foundations. Plastic sheeting should not be placed beneath land- scaped areas adjacent to foundation walls or grade beams. Geo - textile fabric will inhibit weed growth yet still allow natural evapora- tion to occur. CONCRETE Concrete in contact with soil can be subject to sulfate attack. Our experi- ence is that the natural soils in the area of the site contain low concentrations of soluble sulfate. For minimum levels of sulfate concentration, ACI 332-08 Code Requirements for Residential Concrete indicates there are no special require- ments for sulfate resistance. Superficial damage may occur to the exposed surfaces of highly permea- ble concrete. To control this risk and to resist freeze -thaw deterioration, the wa- ter-to-cementitious materials ratio should not exceed 0.50 for concrete in contact with soils that are likely to stay moist due to surface drainage or high-water ta- bles. Concrete should have a total air content of 6 percent +1- 1.5 percent. We recommend all foundations and walls in contact with the subsoils be damp - proofed. ALICE MCDANIEL MCDANIEL RESIDENCE ADDITION PROJECT NO. GS06206.000-120 C:UJserslathatelt3ox\Projects\Glenwood Springs - Projects\GS06206.000112012. Reporls1GS06206.000129 R1.docx 8 it GEOTECHNICAL RISK The concept of risk is an important aspect of any geotechnical evaluation. The primary reason for this is that the analytical methods used to develop ge- otechnical recommendations do not comprise an exact science. The analytical tools which geotechnical engineers use are generally empirical and must be tem- pered by engineering judgment and experience. Therefore, the solutions or rec- ommendations presented in any geotechnical evaluation should not be consid- ered risk-free and, more importantly, are not a guarantee that the interaction be- tween the soils and the proposed structure will perform as desired or intended. What the engineering recommendations presented in the preceding sections do constitute is our estimate, based on the information generated during this and previous evaluations and our experience in working with these conditions, of those measures that are necessary to help the building perform satisfactorily. Standards of practice continuously change in the area of geotechnical en- gineering. The recommendations provided in this report are appropriate for three years. If the proposed project is not constructed within three years, we should be contacted to determine if we should update this report. LIMITATIONS Our exploratory pits provide a reasonable picture of subsurface conditions at the site. Variations in the subsurface conditions not indicated by the pits will occur. A representative of our firm should be called to observe the completed foundation excavation to confirm that the exposed soils are as anticipated and suitable for support of the footings as designed. ALICE MCDANIEL MCDANIEL RESIDENCE ADDITION PROJECT NO. GS06206.000-120 C: UserslathatelBox4ProJects\Glenwood Springs - Projects\GS06206.0004120\2. Reports4GS06206.000 120 R1 docx 9 This investigation was conducted in a manner consistent with that level of care and skill ordinarily exercised by geotechnical engineers currently practicing under similar conditions in the locality of this project. No warranty,'express or im- plied, is made. If we can be of further service in discussing the contents of this report, please call. Jes D. Kellogg, P.E. Di ision Manager JM:JDK:at cc: Via email to alirad1OOOCa,,gmaiLcom ALICE MCDANIEL MCDANIEL RESIDENCE ADDITION PROJECT NO. GS06206.000-120 C:lUserslathate\Box\ProjectslGIenwood Springs - Projects 1G506206.0 0 011 2012. Reports1GS06206.000 120 R1.docx 10 S06207.000_FI 01mE- 2 1 i SCALE: 1' = 1,000' Alice McDaniel McDaniel Residence Addition Project No. GS06206.000-120 Vicinity Map Fig. 1 GS06207.000_F2 01/31 /1 a IN) SCALE: 1" 30' Telephone Pedestal Clean -outs (4" PVC Risers) '12'1 12" 611. 51 70' QIt UEln TP -2 • 12" 74. . c.12 . • . • • $" ' 8.53.9' co 9.6' Cu 1 Story Stucco 5.9' House FF 5245.37' 26,3' ts.: • - • • •_• 1,•1, LI) - 16" 16". • • -.;• • •-•-, Gv rael rthrZ ew37. • . • • a • • -164 'se - Sep Covered Concrete Patic 4L5' Block l'•• Building (9, LEGEND: TP -1 APPROXIMATE LOCATION • OF EXPLORATORY P1T. Alice McDaniel MoDaniel Residence Addition Project No. GS06206.000-1 20 Shed Locations of Exploratory Pits Fig. 2 DEPTH - FEET C:\USERBITWHLTE1APPDATAILOCALIBOXIBOX EDInDOCUMENT51DI3QQ5BOOKO3FHT21UMTKQ=1GS06206.000120 BORING LOG FIGURE 3.GPJ 5 --10 TP -1 TP -2 LEGEND: 0- J T SANDY CLAY "TOPSOIL", ORGANICS, MOIST, II BROWN. 5 10 --- 15 15 - ALICE MCDANIEL MCDANIEL RESIDENCE ADDITION PROJECT NO. GS062C6.000-120 GJ w w F�- n w CJ -7 ✓f % V) b NOTES: CLAY, SANDY, STIFF, MOIST, BROWN (CL) SAND, GRAVEL, CLAYEY, COBBLES, BOULDERS, DENSE, MOIST, BROWN. (SC, GC) INDICATES HAND DRIVE SAMPLE. INDICATES BULK SAMPLE. 1. EXPLORATORY PITS WERE EXCAVATED WITH A TRACKHOE ON JANUARY 30, 2018 2. LOCATIONS OF EXPLORATORY PITS ARE APPROXIMATE. 3. FREE GROUNDWATER WAS NOT FOUND IN OUR EXPLORATORY PITS. q, EXPLORATORY PITS ARE SUBJECT TO THE EXPLANATIONS, LIMITATIONS AND CONCLUSIONS CONTAINED IN THIS REPORT. Summary Logs of Exploratory Pits FIG. 3 4 3 2 } 0 2 3 4 5 -6 O • -7 z a X B w c- z O 9 0 IZ -10 0 0 -11 ADDITIONAL COMPRESSION UNDER CONSTANT PRESSURE DUE TO WETTING 0.1 APPLIED PRESSURE - KSF Sample of CLAY, SANDY (CO From TP -1 AT 2 FEET ALICE MCDANIEL MCDANIEL RESIDENCE ADDITION PROJECT NO. GS06206.000.120 .0 10 100 DRY UNIT WEIGHT= • 93 PCF MOISTURE CONTENT= 21.9 % Swell Consolidation Test Results FIG. 4 HYDROMETER ANALYSIS 25 HR. 7 HR. 45 MIN 15 MIN. 100 90 80 070 co d 60 I - z 50 w 440 30 20 10 0 .001 TIME READINGS 60 MIN- 19 MIN. 4 MIN. 1 MIN. SIEVE ANALYSIS U.S. STANDARD SERIES "200 "100 "50 "40 '10 '16 '10 '8 pppmp MEK _WOPM= MMEM CLEAR SQUARE OPENINGS '4 319" 314" 1)S" 0" ;" 0" 6" 0.002 10 20 30 40 50 60 70 90 -- 100 .005 ,009 .019 .037 .074 .149 -2970.42 .590 42.590 1_19 2,0 2.36 4.76 9.52 19.1 36.1 76.2 12152200 DIAMETER OF PARTICLE IN MILLIMETERS CLAY (PLASTIC) TO SILT (NON -PLASTIC) SANDS FINE MEDIUM I COARSE GRAVEL FINE I COARSE COBBLES Ja m4El wi Sample of SAND, CLAYEY (SC) From TP - 1 AT 5-7 FEET GRAVEL 21 % SAND 45 % SILT & CLAY 34 % LIQUID LIMIT oh PLASTICITY INDEX HYDROMETER ANALYSIS SIEVE ANALYSIS CLEAR SQUARE OPENINGS '4 3!8" 314" VA" 3" 5" 6" 0 25 HR, 7 HR. TIME READINGS 45 MIN. 15 MIN. 60 MIN, 19 MIN. 4 M1N. 1 MIN. '200 100 90 80 070 <50 r - LL -50 ce °+10 30 20 10 0 .001 U.S. STANDARD SERIES '100 '50 '40 "30 '16 '10 '8 Er ^�1 -AMOMElri _NIS ■fiMEN'Err= 1•1 rte^__ � _ ,r��^� ww•M�iw��r-- - �� i�w�w���--- rte __, E -- =IM �^ .�� . C CC= .�. - . 1.11 1 -WON ""�..'.. 0.002 .005 .009 .019 .037 .074 .149 .297 .500 1.19 20 2.38 4.76 9.52 19.1 36.1 0.42 DIAMETER OF PARTICLE IN MILLIMETERS CLAY (PLASTIC) TO SILT (NON -PLASTIC) FINE SANDS MEDIUM I COARS FINE GRAVEL 10 20 30 fal x 40 17. 50 M U 60 70 80 90 100 76.2 12 200 152 COARSE COBBLES Sample of SAND, CLAYEY (SC) From TP - 2 AT 5-7 FEET ALICE MCDANIEL MCDANIEL RESIDENCE ADDITION PROJECT NO. GS06206.000.120 GRAVEL 30 % SAND SILT & CLAY 31 % LIQUID LIMIT PLASTICITY INDEX Gradation Test Results 39 % % % FIG 5 TABLE 1 SUMMARY OF LABORATORY TESTING PROJECT NO. GS06206.000-120 EXPLORATORY PIT TP -1 TP -1 TP -2 DEPTH (FEET) 2 5-7 5-7 MOISTURE CONTENT (%) DRY DENSITY (PCF ATTERBERG LIMITS LIQUID LIMIT -(%) SWELL TEST RESULTS* PLASTICITY INDEX (%) SWELL (% APPLIED PRESSURE (PSF) PERCENT GRAVEL (%) PERCENT SAND (%) PASSING NO. 200 SIEVE (%) DESCRIP—ION 21.9 15.2 14.2 93 36 37 11 11 -0.4 1000 21 30 45 39 34 31 CLAY. SANDY (CL) SAND. CLAYEY (SC) SAND, CLAYEY (SC) l " SWELL MEASURED WITH 1000 PSF APPLIED PRESSURE, OR ESTIMATED IN-SITU OVERBURDEN PRESSURE. NEGATIVE VALUE INDICATES COMPRESSION. Page 1 of 1