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HomeMy WebLinkAboutSubsoil StudyL:ff Ëngineering, lnc. REüE¡ v,.:" JIJN 2 4 2ü22 GARFIELD COUNTY COMMUNITY DEVELOPMENT cfvI:JcssTßc¡{N:cÀL SOIL AND FOUNDATION INVESTIGATION F'OR A PROPOSED RESIDENCE LOT 1, THE RANCH AT COULTER CREEK PUD AT CATTLE CREEK RIDGE ROAD GARFIELD COUNTY, COLORADO PROJECT NO. 19.3377 NOVEMBER 9,2019 .r*4S.,î&+¿-, ,'Sþ:o*''" ":.ri:."ffi"t', : -.fi:.:: : .** * "/\,L*'JJ{ tffi;W*'ii;,*ïï,",1,:,Y"' 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 rvww.LKPEnqineering.com TABLE OF CONTENTS EXECUTIVE SUMMARY ............ SCOPE OF STUDY SITE DESCRIPTION.. PROPOSED CONSTRUCTION...... FIELD INVESTIGATION SUBSURFACE SOIL AND GROUNDWATER CONDITION ... F OLIND ATION RE C O MMENDATION S SLAB CONSTRUCTION.... RETAINING WALLS UNDERDRAIN SYSTEM SITE GRADING AND DRAINAGE....... LAWN IRRIGATION ............... LIMITATION FIGURES LOCATION SKETCH SUBSURFACE EXPLORATION LOGS. SWELL-CONSOLIDATION PERIMETER DRAIN DETAIL. 2 2 2 J J J 4 5 6 6 7 7 8 .DRAWING NO. 1 .FIGURE NO's 1-2 . FIGURE NO's 3-4 .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 11, 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 Garfreld 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 I 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 finalized plans differ significantly from the above understanding, they should notiÛr us to reevaluate the recommendations of this report. FIELD INVESTIGATION The field investigation, conducted on November 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 GROUNDWATBR 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 pits. 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 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. 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 bottorn 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 and tested by the undersigned engineer to verify that the soil conditions encountered during construction are as anticipated in this report. If swelling soils are encountered during the open hole observation, the foundation vvill have to be redesigned to account þr the soil conditions prevailing in the foundation excavation. We recommend a minimum width of 16 inches for the continuous footings and 2 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 rninimum 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 l00o/o 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 soft 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 are 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 of 360 psf can 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 2percent 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 114 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 polyethylene moisture barrier glued to the foundation wall. The drain pipe should be covered with a minimum of 6 inches of -3/4-inch free-draining granular material. Geotextile (Mirafi l40N 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 95o/o 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 l0 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 infilhating 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 wawanty 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.l and on assumptions stated in the report. Soil conditions at other locations ma)¡ varv. 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 11, The Ranch at Coulter Creek PUD, at Cattle Creek Ridge Road, Carbondale, Garfield County, Colorado. Sincerely, LKP ENGINEERING,INC. \¿ ¿f-'-;ffiãr*t**Z.ë.? Luiza Petrovska, PE J:\ WP X4-LKP\ 2019\19-3377 CLAY-BASALT-PITS.DOCX LKP Engineering, Inc rTt,3ãô*.....-iiI,ñ.i9ffi4å>zTOT+¡mo".x==*lrñ8->-+6óZZOolÌ@i>TØmE+umñø>1>le42Øm3Fot!i¡trôz!ÞFf¡tû\oo\ùèI9_@!-9pu9@o@tôox9r:x=-{9{u_x-uÔrof@o='IolÞ'rñFoRllo?C^Hìatrt-o-tô>c)-¡>-J'ï-lIñlm5i"{8fiı=xË-ì4cioHoPfíF9ðdooooÅm^!aomoIz9(o(,(,!--,tØoITIII--¡oIn€zoz9 DATE OBSERVED: NOVEMBER 5, 2019 ELEVATION: Test Pit f I DEPTH FEET 5 Y M B o L s A M P L E DESCRPNON OF MA\ERIAL AND SAMPLE LOCANON LABORATORY TEST RESULTS REMARKS 5 _10 -15 _20 / Topsoil, sÍlty wìth fìne roots over blocky clay r-l Lìght brown to reddish, colcoreous, g¡psiferous, silty cloy with volconic rocks ond pockets of sondy grovel DD: 98.4 pcf MC: 14.7 % Bottom of Test Pìt @ 7.J feet No Ground \Uater Encountered I,EGEND: trI DD MC - 2-ínch 0.Ð. Colifornio Liner Somple - Bulk Somple - Naturol Dry Density (pcf) - Natural Moisture Content (%) - Percent Passing No. 2O0 Sieve - LìquÍd LimÌt - PlosticÍty lndex - Ground water 200 LL PI GW IJ(P ENGINEERING, INC.SUBSURFACE EXPTORATION tOG ffiøECf NO.:l9-JJ77 nq)RE NO.:I DATE OBSERVED: NOVEMBER 5, 2019 ELEVATION: Test Pit f 2 DEPfH FEET 5 Y M B o L 5 A M P L E DESCRIPTION OF MATERIAL AND SAMPLE LOCANON LABORATORY TEST RESULTS REMARKS 5 _10 -15 _20 / Topsoì|, sìlty with fine roots over blocky cloy tr r-l Líght brown to reddish, colcoreous, g¡psiferous, sílty cloy with grovel síze volcanic rocks DD= 99.1 pcf MC: 10.9 % DD= 95.9 pcf MC= 19.5 % Bottom of Test Pìt @ 7 feet No Ground Woter Encountered LEGEND: tl - 2-inch O,D. Colifornìa Liner Somple¡ - Bulk SompleDD - Notural Dry Density (pcf) MC - Naturol Moìsture Content (7) -200 - Percent Passìng No. 2OO SieveLL - Liquîd LimitPl - Plostìcity lndexGW - Ground woter tKP ENGINEERING, INC.SUBSURFACE Ð(PTORATION tOG PROIECT NO.:'t9-3377 ndtRE No.:2 0 c.9 (r) eo ,ìo bR co'E -4(¡) a- Eoo-5 _z -l -2 -6 -1 -2 2 -4 -5 0 c.e (¡t fo a- 'ı N co (D fn Pa- Eoo -6 LKP Engineering, lnc.Swell - Consolidation Test Results PRO,ECT NO.:t9-3J77 NAURE NO,:J tttttttttt .COMPRESSION WHEN WETTED UNDER CONSTANT PRESSURE OF IOOO PSFlltttttttt o.t 1.0 10 't00 APPLIED PRESSURE - ksf Somple of: Light brown, colcareous, g¡¡psiferous, silty cloy Noturol Dry Unít Weight 98.4 pcf Noturol Moisture Content : 14.7 percent From: Test Pit I ot 7.3' t t tt|| t t 4OMPRESSION WHEN WETTED UNDER CONSTANT PRESSURE OF |OOO PSFtltttttttr \ \ o.t 1.0 'to 100 APPLIED PRESSURE - ksf Somple of: Light brown, sondy, calcareous cloy Noturol Dry Unit WeÍght : 99.1 pcf Naturol Moìsture Content : 10.9 percent From: Test Pit 2 of 3.5 feet I 0 c.e(t,cù ,ìo N to'B -4 Pa- Foo-s -3 -l -2 -6 t tl||t t t /COMPRESSION WHEN WETTED UNDER CONSTANT PRESSURE OF 'IOOO PSF 0.1 1.0 10 't00 APPLIED PRESSURE - ksf Sample of:Light brown, clocoreous Cloy Naturol Dry Unit Weight 95.9 Notural Moisture Content : 19.5 From: Test PÍt No. 2 of 7 feet pcf percent LKP Englnccrlng, lnc.Swell ConsolÌdation Test Results t9-JJ77 4 AWAY FROM BUILDING BACKFILL WITH A MINIMUM OF ONE FOOT OF RELATIVELY IMPERVIOUS SOIL FABRTC (MrRAFr l40N oR EOUTVALENT) 3/4-INCH DIAMETER, COARSE, CLEAN CRUSH ROCK 30 MIL MINIMUM THICKNESS,NCH DIAMETER PERFORATED PIPE SLOPED TOPLASTIC LINER, GLUED TO A DAYLIGHT LOCATION AWAY FROM THE FOUNDATION AT 1/4-INCH PER FOOT FOR FLEXIBLE AND 1/B-INCH MINIMUM FOR RIGID PIPE FOUNDATION WALL CML/GEOTECHNICÂL Engineering, fnc. P.O. Box 724, Eoqle, C0 81631 Tel (970) 390-0J07 www.LKPEngineering.com LKP PERIMETER DRAIN LOT 1, THE RANCH AT COULTER CREEK CATTLE CREEK RIDGE ROAD GARFIELD COUNTY, COLORADO 19-3377 scALE: N.T.s.