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HomeMy WebLinkAboutSoils Report 03.12.2019I(1 A Kumar & IJMit_ :rt Inc. Geotechnical and Materials Engineers and Environmental Scientists 5020 County Road 154 Glenwood Springs, CO 81601 phone: (970) 945-7988 fax: (970) 945-8454 email: kaglenwood@kumarusa.com An Employes Owned Company www.kumarusa.com Office Locations: Denver (HQ), Parker, Colorado Springs, Fort Collins, Glenwood Springs, and Summit County, Colorado 4,0 0 d wociatej 4t 3Q, •IrWiW167fI1Si •COM SUBSOIL STUDY FOR FOUNDATION DESIGN PROPOSED OFFICE BUILDING LOT 9, BIG R SUBDIVISION BIG R ROAD, EAST OF RIFLE GARFIELD COUNTY, COLORADO PROJECT NO. 19-7-143 MARCH 12, 2019 PREPARED FOR: Z CONSTRUCTION ATTN: LARRY ZUGSCHWERDT 0311 HANDY DRIVE CARBONDALE, COLORADO 81623 zcuustructionbuiiilcr'sw rx>raiiY.ct,Ikti TABLE OF CONTENTS PURPOSE AND SCOPE OF STUDY - 1 - PROPOSED CONSTRUCTION - 1 - SITE CONDITIONS - 1 - FIELD EXPLORATION - 2 - SUBSURFACE CONDITIONS - 2 - FOUNDATION BEARING CONDITIONS - 3 - DESIGN RECOMMENDATIONS - 3 - FOUNDATIONS - 3 - FLOOR SLABS - 4 - SURFACE DRAINAGE - 4 - 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 Kumar & Associates, Inc. Project No. 19.7-143 PURPOSE AND SCOPE OF STUDY This report presents the results of a subsoil study for a proposed office building to be located on Lot 9, Big R Subdivision, Big R Road, east 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 Z Construction dated February 15, 2019. 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 building will be a single story, wood frame structure, 28 by 40 feet in plan size, located in the extreme southern part of the lot as shown on Figure 1. Ground floor will be structurally supported over crawlspace. Grading for the structure is expected to be relatively minor with cut depths between about 2 to 3 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 lot is currently used for equipment and materials storage and has undergone some apparent minor grading. The minor grading appeared to consist primarily of gravel surfacing and a concrete slab area adjacent the proposed building. The terrain is relatively flat with a slight slope Kumar & Associates, Inc. Project No. 19-7-143 2 down to the south. Elevation difference across the proposed building foot -print is estimated at about one foot. FIELD EXPLORATION The field exploration for the project was conducted on February 21, 2019. 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 Kumar & Associates. Samples of the subsoils were taken with 13/8 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 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 is shown on Figure 2. The subsoils encountered, below about '/2 foot of clayey sand and gravel fill, consisted of interlaid sand and clay that was loose to medium stiff, and extended down to the boring depth of 21 feet. Laboratory testing performed on samples obtained from the boring 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 soils, presented on Figures 3 and 4, indicate moderate to high compressibility under conditions of loading and wetting. The higher compressibility was encountered in the deeper, very moist to wet sample at 15' depth. The laboratory testing is summarized in Table 1. No free water was encountered in the boring at the time of drilling. The subsoils were moist becoming very moist to wet with depth. Kumar & Associates, Inc. Project No. 19.7-143 3 FOUNDATION BEARING CONDITIONS The sand and clay soils possess low bearing capacity and, in general, moderate settlement potential under light foundation loadings. Lightly loaded spread footings bearing on the natural soils should be feasible for foundation support of the building. Excavations deeper than about 4 or 5 feet will likely encounter very moist and more compressible soils which may require subexcavation and replacement with coarse granular soils to stabilize the subgrade. Providing a depth of imported granular structural fill below the footings could be done to reduce the settlement risk. If recommendations for structural fill below the footings are desired, we should be contacted. 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 soils with some risk of settlement. The risk of settlement is due primarily to the compressible nature of the subsoils. 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 1,000 psf. Based on experience, we expect settlement of footings designed and constructed as discussed in this section will be about 1 to 1'/2 inches. 2) The footings should have a minimum width of 20 inches for continuous walls and 21/2 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. Kumar & Associates, Inc. Project No. 19-7-143 A perimeter foundation drain around shallow crawlspace areas (less than 4 feet deep) should not 4) -4 Continuous foundation walls should be heavily reinforced top and bottom to span local anomalies and better withstand the effects of some differential movement 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 firm natural soils and the subgrade compacted. Soft subgrade areas may require subexcavation and replacement with coarse granular soils. 6) A representative of the geotechnical engineer should observe all footing excavations prior to concrete placement to evaluate bearing conditions. 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 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 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 soils with moisture content near optimum and devoid of topsoil, or imported road base can be used. SUR FACE DRAINAGE be needed with adequate compaction of foundation backfill and positive surface drainage away Kumar & Associates, Inc. Project No. 19-7-143 5 from foundation walls. 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 21/2 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. 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 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. Kumar & Associates, Inc. Project No. 19.7-143 6 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, Kumar & Associates, Inc. David A. Young, P.E. Reviewed by: Steven L. Pawlak, P.E. DAY/kac Kumar & Associates, Inc. Project No. 19.7-143 25 0 25 50 APPROXIMATE SCALE—FEET 19-7-143 Existing Road BIG R ROAD 20' 0 LOT 10 TO HIGHWAY 6 PROPOSED BUILDING WELL Kumar & Associates LOCATION OF EXPLORATORY BORING Fig. 1 L — 5 — 10 BORING 1 LEGEND 53. f 7/12 WC=17.6 —200=70 • ffl- 6/12 WC=14.6 DD=104 4 Y - 4/12 So. WC=20.8 4 DD=99 7.77 d4 FILL; MAN—PLACED CLAYEY SAND AND GRAVEL, FIRM, VERY MOIST, BROWN. SAND AND CLAY (SC—CL); INTERMIXED, SILTY, LOOSE/MEDIUM STIFF, VERY MOIST TO WET WITH DEPTH, BROWN. DRIVE SAMPLE, 2—INCH I.D. CALIFORNIA LINER SAMPLE. DRIVE SAMPLE, 1 3/8—INCH I.D. SPLIT SPOON STANDARD PENETRATION TEST. 7/12 DRIVE SAI{FLE 81 OW COUNT. INDICATES THAT 7 BLOWS OF A 140—POUND HAMMER FALLING 30 INCHES WERE REQUIRED TO DRIVE THE SAMPLER 12 INCHES. 4 NOTES -- 15j'` 1. THE EXPLORATORY BORING WAS DRILLED ON FEBRUARY 21, 2019 f 1 4/12 WITH A 4—INCH DIAMETER CONTINUOUS FLIGHT POWER AUGER. r WC=27.6 '•% DD=92 2. THE LOCATION OF THE EXPLORATORY BORING WAS MEASURED 4 APPROXIMATELY BY PACING FROM FEATURES SHOWN ON THE SITE ``•% PLAN PROVIDED./ — 20 3. THE ELEVATION OF THE EXPLORATORY BORING WAS NOT I7/12 MEASURED AND THE LOG OF THE EXPLORATORY BORING IS PLOTTED TO DEPTH. 25 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 THE TRANSITIONS MAY BE GRADUAL. 6. GROUNDWATER WAS NOT ENCOUNTERED IN THE BORING AT THE TIME OF DRILLING. 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). 19-7-143 Kumar & Associates LOG OF EXPLORATORY BORING Fig. 2 SAMPLE OF: Silty Clayey Sand FROM: Boring 1 ® 5' WC = 14.6 %, DD = 104 pcf ADDITIONAL COMPRESSION UNDER CONSTANT PRESSURE DUE TO WETTING 1.0 APPLIED PRESSURE - KSF 10 100 Kumar & Associates 1 -' 0 CONSOLIDATION - SWELL —1 —2 —3 —4 • test caul. ocobr ony to {1r wmpIi, tooled. The aUng report olio!! not as nproduovd. nzompl In tat, rLI oul the NMI.n vyprov 1 of Rumor and A6.ppiot.., Inc. Swell CGneordotlon I.HIM10 p.rforrnnd hr occogdonce nigh AVM 0-4546. 19-7-143 SWELL—CONSOLIDATION TEST RESULT Fig. 3 Y 1 —1 —2 .' —3 CONSOLIDATION - SWELL —4 — 5 — 6 — 7 —8 —9 —10 SAMPLE OF: Sandy Silty Clay FROM: Boring 1 ® 15' WC = 27.6 %, DD = 92 pcf Then, test mono appy only to an nernplee Irked. Tho teetkg repel INV not be reproduced. s cepl In lull, WNW! 41,04.1.+!. approval or Iiurnar one Monlotco. Inc. Snell Con.oWalron tniww p. mid In acc.rdonco *4/.ASU NO MOVEMENT UPON WETTING 1.0 APPLIED PRESSURE — KSF 10 1a0 19-7-143 Kumar & Associates SWELL—CONSOLIDATION TEST RESULT 1 Fig. 4 K±A Geotechnical and Materials Engineers and Environmental Scientists kumarusa.com TABLE 1 SUMMARY OF LABORATORY TEST RESULTS Project No. 19-7-143 SAMPLE LOCATION NATURAL MOISTURE CONTENT (%) NATURAL DRY DENSITY WO i GRADATION PERCENT PASSINGNO. 2� E ATTERBERG LiMITs UNCONFINED COMPRESSIVE STRENGTH (psf) SOIL TYPE BORING DEPTH (ft) GRAVEL SAND I CA) ) LIQUID LIMIT Cie) PLASTIC INDEX (%) 1 2'/z 17.6 I 70Sandy Silty Clay 5 14.6 104 Clayey Silty Sand 10 20.8 99 Clayey Silty Sand 15 27.6 92 Sandy Silty Clay 1 June 17, 2019 Mr. David Argo Community Development Department 108 8th Street, Suite 401 Glenwood Springs, CO 81601 Mr. Argo: RE: Building Permit Application for the Big R Subdivision, Lot 9 After review of the criteria for building and associated activities in the City of Rifle Watershed District area, 1 find that the activity and final constructed facility does not meet the minimum requirements for applying for a City of Rifle Watershed Permit. This correspondence releases him from a permitting responsibility with the City of Rifle. I have spoken with Mr. Zugschwerdt and reviewed his building plans and 1 am assured that his is a low/minor impact to the watershed and does not rise to regulatory necessity. If there are any questions regarding this matter, please don't hesitate to contact me. Respectfully, Brian G. Prunty Public Works Director City of Rifle CITY OF RIFLE 202 RAILROAD AVENUE • P.O. BOX 1908 • RIFLE, CO 81650 WWW. RIFLECO.ORG (970) 665.6559 • FAX (970) 6256268 Andy Schwaller From: Andy Schwaller Sent: Thursday, June 06, 2019 11:31 AM To: 'angiec@eventscaffoldresources.com' Subject: FW: Building Permit Big R From: Andy Schwaller Sent: Thursday, June 06, 2019 11:14 AM To: 'angiec@eventsscaffoldresources.com' <angiec@eventsscaffoldresources.com> Cc: Dave Argo <dargo@garfield-county.com> Subject: Building Permit Big R Adam, We received a building permit application for the above. There is a 20 ft. well/utility setback on the South side of the proposed building. It appears to be between the electrical vault and the South property line. The proposed new structure cannot be built in this setback. I did leave a message with the contractor about the setback. This setback should be surveyed prior to any grading for the structure. Thanks, Andy Schwaller Building Official Garfield County 1