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HomeMy WebLinkAboutSubsoil Study for Foundation Design 01.15.18Engineering, Inc. CIVTUCEOTECHNTCAL SOIL AND FOUNDATION INVESTIGATION FOR A PROPOSED RESIDENCE LOT 32, SUN MEADOW ESTATES sourH MEADOW DRTVE, SrLT GARFIELD COUNTY, COLORADO PROJECT NO. 17.3229 JANUARY 15,2018 RËCEIVED FEB 2 6 2ot8 ..#füiFl,",?P#ilÄ,i fi*\ PREPARED FOR: ABEL MONTANEZ 1179 Érwr 133 #10 CARBONDALE, CO 81623 P.O. Box 724,Eagle, CO 81631 Tel. (970) 390-0307 www.lkpengineering.com I.' : r.t '¿¡' ;i'' ¡. ; . J.,' !ïì ii iri "''i': TABLE OF CONTENTS EXECUTIVE SUMMARY ....... SCOPE OF STUDY SITE DESCRIPTION PROPOSED CONSTRUCTION...... FIELD INVESTIGATION SUBSURFACE SOIL AND GROUNDWATER CONDITION FOUNDATION RECOMMENDATIONS SLAB CONSTRUCTION RETAINING WALLS. LINDERDRAIN SYSTEM SITE GRADING AND DRAINAGE.. LAWN IRRIGATION LIMITATION FIGURES LOCATION SKETCH SUBSURFACE EXPLORATION LOGS SWELL-CONSOLIDATION . . PERIMETER DRAIN DETAIL. 2 2 2 3 J J 4 5 5 6 6 7 7 .DRAV/ING NO. 1 FIGURE NO's l-2 FIGURD NO's 3-4 .FIGURE NO. 5 LKP Engineering,Inc. EXECUTIVE SUMMARY The proposed residence should be supported with conventionaltype spread footings, designed for an allowable soil bearing pressure of 1000 psf. They should construct the footings on the undisturbed silty-sandy clay and/or sandy silt. See tr'oundation Recommendations. SCOPE OF STUDY This report presents the results of a subsurface Soil and Foundation Investigation for a proposed residence to be constructed on Lot32, Sun Meadow Estates, on South Meadow Drive Garfield County, Silt, 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 ore outside ofour scope ofservices. SITE DESCRIPTION Lot32, Sun Meadow Estates is2.002 acres (according to the Garf,reld County Assessor's website) and it is located on South Meadow Drive south from the intersection with Antonelli Lane, in Silt, Garfield County, Colorado. Site plan or a survey were not available. There was a culvert crossing South Meadow Drive and discharging into a shallow ditch running in a westerly direction over the lot. We understand that the proposed building site was planned to be partially on the lower part (north from the ditch) and partially on the upper part (south from the above- LKP Engineering,Inc. 3 described ditch). Vegetation within the proposed building site consisted of grass, bare ground and some snow. There was another deeper ditch running along the west property line. The ditch from the culvert (described above) turned to the southwest and connected with the west ditch. The topography within the selected building arca rppeared moderate with two terraces. Drainage is to the west and southwest. PROPOSED CONSTRUCTION We understand that the proposed residence will be ranch type, wood frame construction with 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 notif,i us to reevaluate the recommendations of this report. FIELD INVESTIGATION The field investigation, conducted on January 9,2018, consisted of logging and sampling two test pits. Approximate locations of the test pits are shown on Drawing No. 1. We show the soil profile of the test pits on the Subsurface Exploration Logs, Figure No's 7 and2. Soil samples for laboratory soil analysis and observation were taken at selected intervals. We understand that you dug the test pits with a mini excavator on rubber tracks prior to our site visit. SUBSURFACE SOIL AND GROUNDWATER CONDITION The soil profiles encountered in the two test pits were fairly uniform. Test Pit No. I had very little topsoil over blocþ clay to about 2.5 feet over light brown, silty sand to sandy silt to the maximum depth explored of 8 feet. Test Pit No. 2 also had very little topsoil over blocþ LKP Engineering, Inc. 4 clay to about 2.5 over light brown, silty sand to sandy silt to about 6 feet over reddish-brown, calcareous, silty clay to the maximum depth explored of 8 feet. Ground water or bedrock was not encountered in the test pits. We sampled the soil in the test pits at random intervals. FOUNDATION RECOMMENDATIONS We recommend that the building site be adjusted to move away from the ditches. The storm runoff from the culvert can saturate the foundation soils and cause settlement in the future. 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 silty-sandy clay and/or sandy silt, below the topsoil and blocþ clay. 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 minimum depth required by the local building code. Thefoundation excavation should be observed by the undersigned engineer to verifi that the soil conditions encountered during construction ore as anticipated in this report. The foundation 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 100o/o of the maximum dry density and within 2percent of the optimum moisture content as determined in a laboratory from a Standard Proctor test (ASTM D-69S). A structural fill, placed under footings should be tested by a qualified profes sional. LKP Engineering, Inc 5 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 frll 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. 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 thc on-sitc carth, should be designed to resist an equivaleut fluid density uf 40 puf fur Lhe "aotive" 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 LKP Engineering,Inc. 6 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 lateralpressure 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 714 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 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 95%o of the maximum standard Proctor density under pavement, sidewalk and patio areas and to at least 90Yo of the maximum standard Proctor density under landscaped areas. They should use mechanical methods of compaction. Do not LKP Engineering,Inc. 7 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 l0 feet of foundation walls, porches or patio slabs. Lawn irrigation must be controlled. 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 otlrcr wat'runty either expressed or inrylied. 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 LKP Engineering,Inc. I 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 ofthe data presented in this report. This report has been prepared for the exclusive use of Abel Montanez, for the specific application to the proposed residence on Lot 32, Sun Meadow Estates, South Meadow Drive, Silt, Garfield County, Colorado. Sincerely, LKP ENGINEERING,INC. R fi,tu,øtùue? Lu;iza Petrovska, PE J:\_WP X4-LKPVO I 8\1 8-3229SILT-CLAY-SAND-PITS.DOCX LKP Engineering,Inc ,f ir , i *" J,- NOTE: THE LOCATION OF THE TEST PITS lS APPROXIMATE. IT IS NOT BASED ON A SURVEY i' j a t cffIL,/GEoTEcHNIcÄI, Engineering, Inc. P.O. Box 7?4, î.ogle, CO 81631 Tel (970) 390-0307 www.lkpengineering.com LKP LOCATION SKETCH LOT 32, SUN MEADOW ESTATES SOUTH MEADOW DRIVE GARFIELD COUNTY, COLORADO PROJÈU I NU.:18-3229 SCALÉ:- 1" = 100' DRAWING NO.: 1 DATE OBSERVED: JANUARY 9, 2018 ELEVATION: TEST PIT-I DEPTH FEET .9 Y M B o L s A M P L E DESCRPNON OF MATERIAL AND SAMPLE LOCATION LABORATORY TEST RESULTS REMARKS 5 _10 -15 20 Blocky-silty cloy DD: 1O2.4 ncf tr Light brown, to reddish-brown, sandy Silt to silty Sond MC: 5.3 % DD: 95.6 pcf MC: 3.5 % Bottom of Test Pit at I feet No Ground woter encountered LEGEND: trI DD MC - 2-inch O.D. Colifornia Liner Somple - Bulk Sample - Noturol Dry Density (pcf) - Notural Moisture Content (7") - Percent Passing No. 2O0 Sieve - Liquid Limit - Plosticity lndex - Ground woter -200 LL PI GW tKP ENGINEERING, INC.SUBSURFACE EXPLORATION LOG PRO,ECT NO.:18-3229 IñAURE NO,: DATE OBSERVED: JANUARY 9, 2018 ELEVATION: TEST PIT_z DEPTH FEET s Y M B o L s A M P L E DESCRIPTION OF MATERIAL AND SAMPLE LOCANON LABORATORY TEST RESULTS REMARKS 5 -10 -15 20 Blocky-silty cloy tr Light brown, to reddish-brown, sandy Silt to silty Sond DD: 94.5 MC: 4.9 PCf tr Light to reddish-brown, silty Clay, colcareous DD: 101.3 pcf MC: 7.2 % Bottom of Test Pit at I feet No Ground woter encountered LEGEND: trI DD MC - 2-inch O.D. California Liner Sample -200 - Bulk Somple - Noturol Dry Density (pcf) - Noturol Moisture Content - Percent Possing No. 200 - Liquid Limit - PlastÍcity lndex - Ground woter (7") Sìeve LL PI GW tKP ENGINEERTNG, INC.SUBSURFACE EXPTORATION tOG FKUÈÇ I NU.:t8-3229 Nd'RE NO,:2 2 o -6 .E v, sI ¡t c.9 Ut0t Eq- s -2 -4 -8 -2 -4 -6 -l 2 o -6 .E u, s.*l¡J ùt t.e Ut o)s\ ÈI \ \ \ APPLIED PRESSURE - kef 0.t t.o îo t00 Somple ofrLíght brown, sandy Sìlt, claycyFrom:Test Pìt No. I of 2.5 feet Noturol Dry Unìt Weíght Natural lloísture Contant - 5.J percent co}rLrb,b[t,[trr or)ro uhorh I coîlsrîYr rfllïuRE oF l00o Ís\ | 0.t APPUED PRESSURE - ksf to1.O tæ Sample of:Lt. brown, sondy Silt Noturol Dry Unìt lleíght Natural Moisture Content = From: Teet Pit No. 1 ot I feet Pcfpercent 95.6 J.5 Swell - Consolidotíon Test Results 3LKP EnglnccrÍng, lnc. 2 o -2 -4 -6 -8 c .9 u, s*t¡J Ùt c.9 ttt 1t6 a- EI -1 2 0 -2 -1 -6 -8 .E at, sI ùr co v,v, E ÈI -l càurhridolutlrrr o,\to hoìr I corvslÁfrlPlRFfsuRE oF I t ool Psl I \ \ \ \ APPUED PRESSURE - ksf o.t 1.O îo ,00 Sampla otLÍght brovn, sÍlty sond, fÍno Noturol Dry Unlt Weight = 94.5 Notural Moìeture Content - 4.9 From: Tcst Plt No, 2 ot 4 fcdt pcf pcrccnt - cohpnisslolt h#rt orn t rrr[ | colsrlNrt"frlîí"F oF t00? PsFt I \ \ APPUED PRESSURE - ksf o.l 101.O îo0 Sample ofrLt. brown, colcoreous Noturol Dry Unlt Weight Noturol Molsture Content = Clay, sandy F¡om: Test Plt Nd 2 at 6 feet,0'1.3 pcf7.2 Percent LKP EngÍnccrîng, lne Swell - Consolídation Test Results 4 rywF AWAY FROM BUILDING BACKFILL WITH A MINIMUM OF ONE FOOT OF RELATIVELY IMPERVIOUS SOIL FABRTC (MtRAF| 140N OR EOUTVALENT) NUS 3/4-INCH DIAMETER, COARSE CLEAN CRUSH ROCK 30 MIL MINIMUM THICKNESS,DIAMETER PERFORATED PIPE SLOPED TO PLASTIC LINER, GLUED TO A DAYLIGHT LOCATION AWAY FROM ÏHE FOUNDATION AT 1/4-INCH PER FOOT FOR FLEXIBLE AND 1/8-INCH MINIMUM FOR RIGID PIPE FOUNDATION WALL ' 'Þ ' FoorlNG D Þ ÞÞ ì S IoñN\a s R ' 'Þ ? Þ Þ' Þ CML/GEOTECHNICAI, Engineering, Inc. P.O. Box 724, Eosle, CO 81631 Tel (970) 390-0J07 www.lkpengineering.com LKP PERIMETER DRAIN LOT 32, SUN MEADOW ESTATES SOUTH MEADOW DRIVE GARFIELD COUNTY, COLORADO PHo.tLCt NU.: ß4229 scALE: N.T.s. 5 flGURE NO;