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HomeMy WebLinkAboutSubsoil Study for Foundation Design 11.9.2019Íngineeríng Inc. CTVIIJûECITECÍIMCAL SOIL AND FOUNDATION INVESTIGATION FOR A PROPOSED RESIDENCE LOT I., THE RANCH AT COULTER CREEK PUD AT CATTLE CREEK RIDGE ROAD GARFTELD COUNTY, COLORADO PROJECT NO. 19.3377 NOVEMBER 9,2019 PREPARED FOR: ROBERT LEVIN LEVINIUS LLC 218 E. VALLEY ROAD, STE 104 PMB 375 CARBONDALE, CO 81623 P.O. Box 724,Eagle, CO 81631 Tel. (970) 390-0307 www.LKPEnsineering.com TABLE OF CONTENTS EXECUTIVE SUMMARY. SCOPE OF STUDY SITE DESCRIPTION PROPOSED CONSTRUCTION.. FIELD INVESTIGATION SUBSURFACE SOIL AND GROIINDWATER CONDITION . FOLINDATION RECOMMENDATIONS . SLAB CONSTRUCTION RETAINING WALLS UNDERDRAIN SYSTEM ................ SITE GRADING AND DRAINAGE LAWN TRzuGATTON ................. LIMITATION. FIGURES LOCATION SKETCH SUBSURFACE EXPLORATION LOGS SWELL-CONSOLIDATION PERIMETER DRAIN DETAIL. 2 2 2 3 aJ J 4 5 6 6 7 7 8 . . . .DRAWING NO. 1 . . . .FIGURE NO's 1-2 ,...FIGURENO's3-4 . . . .FIGURE NO. 5 LKP Engineering,Inc. EXECUTIVE SUMMARY The proposed residence should be supported with conventional type spread footings, designed for an allowable soil bearing pressure of 1000 psf. They should construct the footings on the undisturbed calcareous, gypsiferous, silty clay with some gravel. See Foundation Recommendations. SCOPE OF STUDY This report presents the results of a subsurface Soil and Foundation Investigation for a proposed residence to be constructed on Lot 1 1, The Ranch at Coulter Creek PUD, at Cattle Creek Ridge Road (address number not assigned yet), Garfield County, Carbondale, Colorado, The purpose of the subsurface soil and foundation investigation was to determine the engineering characteristics of the foundation soil and to provide recommendations for the foundation design, grading, and drainage. Geologic hazard studies are outside of our scope of services. SITE DESCRIPTION Lot 11, The Ranch at Coulter Creek PUD is 9.637 acres (according to the survey by SGM, Inc, Robert Brandeberry, PLS, emailed by Whit and the Garfield County GIS) and it is located at the southeast from the intersection of Cattle Creek Ridge Road and Meadow Circle, and south from 1003 Cattle Creek Ridge Road, Garfield County, Colorado. Vegetation within the proposed building site consisted of tall grass. The topography within the selected building LKP Engineering,Inc J area (where the two test pits had been dug) was flat to moderate with average slopes from about 5 percent. Drainage is to the south and southeast. Cattle Creek Ridge Road runs along the west side, southwest and south side of the property. To the north there is an existing residence and to the east is the Ranch at Coulter Creek PUD Private Open Space. Lot 1 was vacant. PROPOSED CONSTRUCTION 'We have assumed that the proposed residence will be two story, wood frame construction without a basement, on a concrete foundation, with an attached garage. We anticipate loads to be light, typical of residential construction. If the finalizedplans differ significantly from the above understanding, they should notifu us to reevaluate the recommendations of this report. FIELD INVESTIGATION The field investigation, conducted on Novemb er 5 , 2019, consisted of logging and sampling two test pits. The test pits were dug by your excavator, Ryan Ivy. Approximate locations of the test pits (as marked by you) are shown on Drawing No. 1. We show the soil profile of the test pits on the Subsurface Exploration Logs, Figure No's 1 and2. Soil samples for laboratory soil analysis and observation were taken at selected intervals. SUBSURFACE SOIL AND GROUNDWATER CONDITION The soil profiles encountered in the two test pits were fairly uniform. Test Pit No. I had about 3 feet of topsoil and blocky clay over light brown, calcareous, gypsiferous, silty clay with basalt gravel to cobble size rocks and pockets of sandy gravel, to the maximum depth explored of about 7.3 feet. Test Pit No. 2 had about 2.5 feet of topsoil and blocky clay over light brown to LKP Engineering,Inc. 4 reddish, calcareous, gypsiferous, silty, sandy clay with gravel size volcanic rocks to the maximum depth explored of 7 feet. Ground water or bedrock were not encountered in the test pitir. We sampled the soil in the test pits at random intervals. The samples were tested for natural moisture content, swell-consolidation potential, and natural dry density. The test results are shown on Figure numbers 3 and 4.The clay soil samples had high moisture content of I4.7 and 19.5 percent. The high moisture content might mask possible swelling potential of the clay soils. Swelling soils were encountered on the surrounding lots. FOUNDATION RECOMMENDATIONS The proposed residence should be supported with conventional type spread footings, designed for an allowable soil bearing pressure of 1000 psf. They should construct the footings on the undisturbed calcareous, gypsiferous, clay with some gravel, below the topsoil and blocky clay. If the entire foundation is supported on the clay soil encountered at the bottom of the test pits at depth of 7 feet, they can use a maximum allowable soil bearing pressure of 2000 psf. The clay soil samples had high moisture content of 14.7 and 19.5 percent. The high moisture content might mask possible swelling potential of the clay soils. Swelling soils were encountered on the surrounding lots. The completedfoundation excavation must be observed ønd tested by the undersìgned engineer to verify that the soil conditions encountered during construction are os anticipated in this report. If swelling soils are encountered during the open hole observation, the þundation will ltave to be redesigned to account þr the soil conditions prevailing in the foundation excavation. We recommend a minimum width of l6 inches for the continuous footings and2 feet for the isolated footing pads. Continuous foundation walls should be reinforced top and bottom to span an unsupported length ofat least 10 feet. The proposed foundation should be set at a minimum depth of four feet below the finished grade or at the minimum depth required by the local building code. The foundation LKP Engineering,Inc 5 excavation should be free from excavation spoils, frost, organics and standing water. We recommend proof-rolling of the foundation excavation. Soft spots detected during the proof- rolling, should be removed by overexcavation. Any overexcavation within the proposed foundation should be backfilled, in 8 inches loose level lifts and compacted to 100% of the maximum dry density and within 2 percent of the optimum moisture content as determined in a laboratory from a Standard Proctor test (ASTM D-698). A structural fill, placed under footings should be tested by a qualified professional. SLAB CONSTRUCTION The natural on-site soils, exclusive of topsoil and organics, are suitable to support lightly loaded slab-on-grade construction. The subgrade for the slab-on-grade construction should be proof compacted to detect and remove soft spots. They should backfill overexcavated sofi spots and other underslab fill with the on-site soil, free from topsoil and organics, or other suitable material, compacted to a minimum of 95 percent of the maximum standard Proctor density (ASTM D-698). Suitable material should be free from topsoil, organics and rock fragments greater than 3 inches. The concrete slab should be constructed over a 4-inch layer of clean gravel consisting of -314 inch gravel with at least 50% retained on the No. 4 sieve and less than 3 percent passing the No. 200 sieve. They should reinforce the concrete slab-on-grade and score controljoints according to the American Concrete Institute requirements and per the recommendations of the designer to reduce damage due to shrinkage. The concrete slab should be separated from the foundation walls and columns with expansion joints to allow for independent movement without causing damage. LKP Engineering,Inc. 6 RETAINING WALLS Foundation walls retaining earth and retaining structures that arc laterally supported should be designed to resist an equivalent fluid density of 60 pcf for an "at-rest" condition. Laterally unrestrained structures, retaining the on-site earth, should be designed to resist an equivalent fluid density of 40 pcf for the "active" case. The above design recommendations assume drained backfill conditions and a horizontal backfill surface. Surcharge loading due to adjacent structures, weight of temporary stored construction materials and equipment, inclined backfill and hydrostatic pressure due to undrained backfill should be incorporated in the design. They should try to prevent the buildup of hydrostatic pressure behind the retaining wall. Passive earth pressure of360 psfcan be used for the lateral pressure against the sides of the footings. Resistance to sliding at the bottom of the footings can be calculated based on a coefficient of friction of 0.5. Undisturbed soil or a structural fill compacted to 100 percent of the maximum dry density and within 2 percent of the optimum moisture content will be used to resist lateral loads at the sides of the footings. UNDERDRAIN SYSTEM To reduce the risk of surface water infiltrating the foundation subsoil, we recommend installation of a foundation perimeter drain (see Figure No. 5). The foundation perimeter drain should consist of a 4-inch diameter, perforated pipe, sloped to a suitable gravity outlet, at a ll4 inch per foot for flexible or at a 1/8 of an inch for rigid pipe. The bottom of the trench adjacent to the footing should be lined with a polyetþlene moisture barrier glued to the foundation wall. The drain pipe should be covered with a minimum of 6 inches of -314-inch free-draining granular material. Geotextile (Mirafi 140N or equivalent) should be used to cover the free- draining gravel to prevent siltation and clogging of the drain. The backfill above the drain should LKP Engineering,Inc. 7 be granular material to within 2 feet of the ground surface to prevent a buildup of hydrostatic pressure. SITE GRADING AND DRAINAGE The following recommendations are general. Exterior backfill should be compacted at or near the optimum moisture content to at least 95Yo of the maximum standard Proctor density under pavement, sidewalk and patio areas and to at least 90% of the maximum standard Proctor density under landscaped areas. They should use mechanical methods of compaction. Do not puddle the foundation excavation. The site surrounding the building structure should slope away from the building in all directions. A minimum of 12 inches in the first 10 feet is recommended in unpaved areas, and three inches in the first 10 feet in paved areas. The top of the granular foundation backfill should be covered with a minimum of 1 foot of relatively impervious fill to reduce the potential of surface water infiltrating the foundation subsoils. Surface water naturally draining toward the proposed building site should be diverted around and away from it by means of drainage swales or other approved methods. The roof drains and downspouts should extend and discharge beyond the limits of the backfill. LAWN IRRIGATION It is not recommended to introduce excess water to the foundation soils by installing sprinkler systems next to the building. The installation of the sprinkler heads should insure that the spray from the heads will not fall within 10 feet of foundation walls, porches or patio slabs. Lawn irrigation must be controlled. LKP Engineering,Inc. 8 LIMITATION This report has been prepared according to locally accepted Professional Geotechnical Engineering standards for similar methods of testing and soil conditions at this time. The type of soil testing was selected by the owner and general contractor as the preferred method for the soil and foundation investigation over a soil and foundation investigation with a drill rig. There is no other warranty either expressed or implied. The findings and recommendations of this report are based on field exploration, laboratory testing of samples obtained at the specific locations shown on the Location Sketch, Drawing No.1 and on assumptions stated in the report. Soil conditions at other locations may vary. which may not become evident until the foundation excavation is completed. If soil or water conditions seem different from those described in this report we should be contacted immediately to reevaluate the recommendations of this report. We are not responsible for technical interpretation by others of the data presented in this report. This report has been prepared for the exclusive use of Robert Levin, for the specific application to the proposed residence on Lot 1 1, The Ranch at Coulter Creek PUD, at Cattle Creek Ridge Road, Carbondale, Garfield County, Colorado. Sincerely, LKP ENGINEERING,INC.tsa , Mtr*W LuizaPetrovska, PE J:\_WP X4-LKP\_20 I 9\19 -337 7 CLAY-BASALT-PITS.DOCX 2wö r{ LKP Engineering,Inc II Å I 1 T rtr l*0. \ \ .%. ¡ TEST -2 4{L46' TEST PIT. 1 tüT4l q fLtåcree \ *é w¡Tfu.r \ !f ¡¡rt t ã â å: I ,:, Èt \ \ \tf \ \ T \ \ \ ,þ i "1 ilã rs I NOTE: THE LOCATION OF THE TEST PITS IS APPROXIMATE. IT IS NOT BASED ON A SURVEY. LOCATION SKETCH PROJECT NO.l 19-3377 scALE: - r'=70'LKP Engineering, Inc. clyrLlcEorECHNICAL P.O. Box 724, Eogle, CO 81631 Tel (970) 390-0307 LOT 1, THE RANCH AT COULTER CREEK CATTLE CREEK RIDGE ROAD GARFIELD COUNTY, COLORADO DRAWING NO.; 1 DATE OBSERVED: NOVEMBER 5, 2019 ELEVATION: Test Pit f 1 DEPTH FEET s Y M B o L .s A M P L E DESCRIPNON OF MATERIAL AND SAMPLE LOCANON LABORATORY TEST RESULTS REMARKS 5 -10 _15 _20 Topsoil, silty with fine roots over blocky clay t-l LÍght brown to reddish, celcoreous, glpsÌferous, silty cloy with volcanic rocks and pockets of sandy grovel DD: 98.4 pcf MC: 14.7 % Bottom of Test Pit @ 7.3 feet No Ground Woter Encountered I,EGEND: tr - 2-inch O.D. California Liner SompleI - Bulk Sample DD - Noturol Dry Density (pcf) MC - Notural Moisture Content -200 - Percent Passing No. 200LL - Liquid LìmitPl - Plosticity lndexGW - Ground water (7") Sieve LKP ENGINEERING, INC.SUBSURFACE EXPTORATION LOG PRO,EC| NO,:t9-3J77 IflWRE NA: DAÏE OBSERVED ELEVAÏON: N9yEMBER s, 2019 Test Pit f 2 DEP'IH FEET .s Y M B o L .s A M P L E DESCRPNON OF MATERIAL AND SAMPLE LOCANON LABORATORY TEST RESULTS REMARKS 5 -10 -15 _20 / Topsoil, silty with fíne roots over blocky clay D n Light brown to reddish, colcoreous, g¡psiferous, sìlty cloy with grovel sÍze volcanic rocks DD: 99.1 pcf MC: 14.9 % DD: 95.9 pcf MC: 19.5 % Bottom of Test Pìt @ 7 feet No Ground Vlater Encountered LEGEND: tr - 2-Ínch O.D. Colifornia Liner SompleI - Bulk Sample DD - Noturdl Dry Density (pcf) MC - Noturol Moisture Content (%) -200 - Percent Possing No. 2OO SieveLL - Liquìd LìmitPl - Plosticity lndexGW - Ground woter tKP ENGINEERING, INC.SUBSURFACE EXPLORATION tOG t9-3377 2 o -1 2 -3 c.a rDcù ,ìo N cog, -4(¡) a- Eoo-s I 0 -6 -1 -2 -4 -3 Èo v,eo o- ñ òr co th v) 0)L a_ Fo() -6 LKP Engineering, lnc Swell - Consolidation Test Results 3 rrltltttlt .COMPRESSION WHEN WETTED UNDER CONSTANT PRESSURE OF lOOO PSFl l t || t l 0.1 1.0 't0 100 APPLIED PRESSURE - ksf Sample of: LÌght brown, colcoreous, g¡rpsiferous, silty cloy Notural Dry Unít lr/eÌght Ndturol Moisture Content : 14.7 percent From: Test Pit I ot 7.3' t l ttl|l t 1 4OMPRESSION WHEN WETTED UNDER CONSTANT PRESSURE OF .IOOO PSF llllltti \ \ 0.1 1.0 l0 t00 APPLIED PRESSURE - ksf Somple of: Light brown, sondy, calcareous cloy Notural Dry Unit Weight Noturol Moisture Content : 10.9 percent From: Test Pit 2 of 3.5 feet o -3 È.e Ut Ò a- ,ñ NS co (/) úD (¡)\ a_ Èo() -1 -2 -4 Ã -6 t ttl|lt t t .COMPRESSION WHEN WETTED UNDER CONSTANT PRESSURE OF IOOO PSF ,/ 0.1 1.0 10 t00 APPLIED PRESSURE - ksf Somple of: Light brown, clacoreous Cloy Naturol Dry Unit lt/eight 95.9 Noturol Moìsture Content : 19.5 From: Test Pit No. 2 at 7 feet pcf percent LKP Englnctlng, lnd Swell - Consolidotion Test Results .PROECT NO.:I ts-sszz - Iqd/URE No.: 4 Þ D ÞÞ 'ôÞ FOONNG 4 Þ À ÞÞ {! S R Èf S \Jl.- Þ P LOPE AWAY FROM BUILDING BACKFILL WITH A MINIMUM OF ONE FOOT OF RELATIVELY IMPERVIOUS SOIL FABRTC (MrRAFt 140N OR EQUTVALENT) 3/4-INCH DIAMETER, COARSE CLEAN CRUSH ROCK 30 MIL MINIMUM THICKNESS,INCH DIAMETER PERFORATED PIPE SLOPED TOPLASTIC LINER, GLUED TO TH A DAYLIGHT LOCATION AWAY FROM THE FOUNDATION AT 1/4-INCH PER FOOÏ FOR FLEXIBLE AND 1/8-INCH MINIMUM FOR RIGID PIPE FOUNDATION WALL CML,/GEOIECIINICAL Engineering, Inc. P.O. Box 724, Eãgle, CO 81631 Tel (970) 39o-0307 www.LKPEngineering.com LKP PERIMETER DRAIN LOT 1, THE RANCH AT COULÏER CREEK CATTLE CREEK RIDGE ROAD GARFI ELD COUNTY, COLORADO PROJECï NO.: 19-3377 scALE: N.T.s 5 FIOURE NO.: