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Home My WebLink AboutSubsoil StudyLKP Engineering, Inc. CIVIUGEOTECHNICAL SOIL AND F'OUNDATION INVESTIGATION F'OR A PROPOSED RESIDENCE LOT I, STIRLING RANCH PUD IOO2 SKIPPER DRIVE CARBONDALE GARFIELD COUNTY, COLORADO PROJECT NO. 21-3550 SEPTI,MBER 18,2021 PREPARED FOR: KEVIN L. PATRICK & ANDREA WENDEL 229 M.IDLAND AVENUE BASALT, CO 81621 RECEIVED JUt ì 3 trjt? GARFIELD COUNTY COMMUNITY NEVELOPMEI,JT P.O. Box 724,Eagle, CO 81631 Tel. (970) 390-0307 ''vwrv,l..Kl'finginççr:irlg.tûnt TABLE OF CONTENTS EXECUTIVE SUMMARY ...,...... SCOPE OF STUDY SITE DESCRIPTION..., PROPOSED CONSTRUCTION IIIELD INVESTIGATION ......... SUBSURFACE SOIL AND GROLINDWATER CONDITION .. FOUNDATION RECOMMENDATIONS .....,... SLAB CONSTRUCTION ......... RETAINING V/ALLS.....,..... UNDERDRAIN SYSTEM SITE GRADING AND DRAINAGE LAWN IRRIGATION LrMITATION................ FIGURES LOCATION SKETCH SUBSURFACE EXPLORATION LOGS SWELL-CONSOLIDATION TEST RESULTS PERIMETER DRAIN DETAIL. STRUCTURAL FILL WITH GEOGRID........ ..DRAWING NO, 1 ..FIGURENO's l-2 "..FIGURE NO, 3 ,.FIGURE NO.4 ...FIGURE NO. 5 2 2 2 J J 3 4 5 6 6 7 7 I LKP Engineering, Inc EXECUTIVE SUMMARY The proposed residence should be supported with conventional type spread footings, designed for an allowable soil bearing pressure of2000 psf. They should construct the footings on the undisturbed silty, sandy clay to clayey sand with basalt rocks or structural fill with geogrid. See Foundation Recommendations. SCOPE OF STUDY This report presents the results ofa subsurfacc Soil and Foundation Investigation for a proposed residence to be constructed on a parcel ofLand, Account R008776, Parcel ?3g13A40500l, 1002 Skipper Drive, Carbondale, CO 81623, Lot 1, Stirling Ranch PUD, Garfield County, Colorado. The purpose of the subsurface soil and foundation investigation was to determine the engineering characteristics of thc foundation soil and to provide recommendations for the foundation design, grading, and drainage. Geologic hazard sludies \are outside ofour scope ofservices. SITE DESCRIPTION Lot 1, Stirling Ranch PUD at 1002 Skipper Drive is 6.tt7l+/- acres and it is located on the west side of the Skipper Drive cul-de-sac, Carbondale, Garfield County, Colorado. Directions to the lot from US Highway 82 are via Catherine Store Road to CR 1 02 to CR 162 to Skipper Drive to the end of the road at the cul-de-sac. The dirt driveway goes from the Skippcr LKP Engineering, Inc. J l)rive cul-de-sac though an access easement on Lot 2 to the building envelopc on Lot 1. Vegetation within the proposed building site consisted of sparse grass, juniper trees, small sage brush, cacti, few pine trees, and basalt rocks. The topography was moderate at the upper one third and steep on the rest. Drainagc is to the west and southwest. To the north of the lot is an open space and to the east and west are vacant lots. Lot I was also vacant PROPOSED CONSTRUCTION At the time of the soil and foundation investigation architectural plans have not bcen developed yet. We have assumed that the proposed residence will be two story, wood frame construction with a possible walkout basement, on a concrete foundation, with an attached garagc. We anticipate loads to be light, typical of residential construction. If the finalized plans differ significantly from the above understanding, thcy should notify us to reevaluate the recommendations of this report. FIELD INVESTIGATION The field investigation, conducted on September2,2021, consisted of logging and sampling two test pits. The test pits were dug by Ryan lvy with Deere 60D mini trackhoe, Approximate locations of the test pits are shown on Drawing No. 1. We show the soil profìle of the test pits on the Subsurface Exploration Logs, Figure No's I and 2. Soil samples for laboratory soil analysis and observation were taken at selected intervals. Geologic hazard studies are outside ofour scope ofservices. SUBSURFACE SOIL AND GROUNDWATER CONDITION The soilprofiles encountered in the two test pits were uniform, consisting of about one LKP Engineering, Inc. 4 foot of topsoil over I -3 feet of blocky clay over whitish, calcareous, gypsiferous, silty, sandy clay to clayey sand, gypsiferous, calcareous, with basalt rocks of gravel to cobbles and boulder size to the maximum depth explored of 5.5 and 4 feet respectively. Ground water was not encountered in the test pits. We sampled the soil in the test pits at random intervals.'I'he soil samples were tested in our laboratory for swell-consolidation, natural dry density, and natural moisture content. The test results are shown on Figure No. 3. F'OUNDATION RECOMMENDATIONS The proposed residence should be supported with conventional type spread footings, designed for an allowable soil bearing pressure of 2000 psf. They should construct the footings on the undisturbed silty-sandy clay with basalt gravel, cobbles and boulders, From previous experience with similar soils, it is very likely that excavation of the large basalt rocks to level the foundation excavation for the construction ofthe footings, can leave large voids and uneven subgrade. lf the thickness of the leveling, structural fill is more than 6 to I inches, structural fill improved with Tensar geogrid, as shown on the attached detail, flrgure number 5, will be implemented. The completedþundation excavqtion must be observed and tested by the undersigned engineer to verifu that the soil conditions encountered during construction are os anticipaled in this reporÍ. We recommend a minimum width of l6 inches for the continuous footings and 2 leet for the isolated footing pads. Continuous foundation walls should be reinforced top and bottom to span an unsupported length ofat least l0 feet. The proposed foundation should be set at a minimum depth of four feet below the {ìnished grade or at the minimum depth required by the local building code. The loundation excavation should be free from excavation spoils, frost, organics and standing water. We LKP Engineering, Inc. 5 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 backf,rlled, in 8 inches loose level lifts and compacted to 100% of the maximum dry density and within 2 percent of the optimum moisture contcnt as dctcrmined in a laboratory from a Standard Proctor test (ASTM D-698). A structural hll, placed under footings should be tested by a qualified professional. SLAB CONSTRUCTION The natural on-site soils, exclusive of topsoiland 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 removc 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. If during excavationþr the slab-on-grade similar conditions, qs described in the above foundation recommendations section, with large voids or uneven surjhce are created, structural fill os-describe above and as shown on the Structural fill with geogrid deløil, figure number 4 will be used. The concretc slab should be constructed over a 4-inch layer ofclcan gravel consisting of -3l4-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 dcsigner 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 rccommendations 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 undraíned 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 coefhcient 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 olsurface water intìltrating the f'oundation subsoil, we recommend installation of a foundation perimeter drain (see Figure No. 4). The foundation perimeter drain should consist of a 4-inch diameter, perforated pipe, sloped to a suitable gravity outlet, aT. a l14 inch per foot for flexible or at a l/8 of an inch for rigid pipe. The bottom of thc 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 -3l4-inch free-draining granular material. Geotextile (Mirafi l40N or equivalent) should be used to cover the free- LKP Enginecring, lnc. 7 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 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 l2 inches in the first l0 feet is recommended in unpaved areas, and three inches in the first l0 feet in paved areas. The top of the granular foundation backfill should be covered with a minimum of 1 foot of relatively impervious fìll 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 ensure that the spray from the heads will not fall within l0 feet of foundation walls, porches or patio slabs. Lawn irrigation must be controlled. LKP Engineering, Inc. I LIMITATION This report has been prepared accordíng 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. 'l'he findings and recommendations of this report are based on held exploration, laboratory testing of samples obtained at the specific locations shown on the Location Sketch, Drawing No.I and on assumptions stated in thc rcport. Soil conditions at other locations rn{y varv. which mav not becomc evident untilthe foundati!¡n excavalign is completed. lf soil or water conditions seem different from those desuibed in this report, we should be contacted immediately to reevaluate the recommendations of this report. We are not responsible for tcchnical intcrprctation by othcrs of the data presented in this report. This report has been prepared for the exclusive use of Kevin L. Patrick & Andrea Wendel, for the specific application to the ir proposed residence on Lot l, Stirling Ranch PUD, 1002 Skipper Drive, Carbondale, Garfield County, Colorado. Sincerely, LKP ENGINEERING,INC. ,***o.- l.t?ú ,, .3] :'..:f)r rrr; r'i',' i, i i.ì . M,;,Wu',ii,: ilii,i.i,* Luiza Petrovska, PE J:\*WP X4-LKP\ 2021\2 I -3550CLAY-SAND-BASALT-PITS.DOCX LKP Engineering, Inc. Þ ll/ - /, PROF-I/\ (Þ (F) \€urrÞÍ.Jc Ji.'r-ı .--f -7 ENVËLOPE /enor z \ I I I SK¡PPER DRIVE.i\TEST PIT, 1 "(Þ / / PLATEAU ^r/\/ / / --'-a_ n / /\ / / I / /ì / ( / / ,/ NOTE: THE LOCAfION OF IHE lÊST PllS JS APPROXIMATÉ IT IS ÑO' SASED ON A SURVEY LOCATION SKETCH CMLICEOTECHNICAL 2 I -3550 - l" = 100'1OO2 SKIPPER DRIVE CARBONDALE GARFIELD COUNTY, COLORADO glneenng,nc. com P.O. Box 724, Íogle, CO 816J1 lel (970) J90-OJ07 www, Test Pit f 1DATE OBSÊRVED: SEPTEMBER 2, 2021 ELEVAÏON: LABORATORY.IEST RESULTS REMARKSDEPTH FEET s Y M B o I s A M P L E DESCRPNON OF MA\ERIAL AND SAMPLE LOCANON N ,,W OD: 76.6 pcf MC= 13.3 Ztr Topsoil with roots Reddìsh-brown, blocky clay wÌth bosolt cobbles ond boulders Whitish, silty, clayey sond, col coreous, g¡rpsiferous Bosolt rocks No Ground Woter Encountered Refusol of 5.5 feet on bosolt boulders _t0 -15 _20 5 - Bulk Somple - Noturol Dry Density (pcf) - Noturol Moìsture Content - Percent Possing No. 200 - Lìguid Limit - Plosticity lndex - Ground woter trI DO MC LL PI GW (z) Sieve-200 LEGEND: - 2-inch O.Ð. Colifornio Liner Sample PRO,ECÍ NO.:2t-3550 SUBSURFACE EXPTORATION tOG ndnÊ tfrJ ItKP ENGINEERTNG, INC. Test Pit ¡f; 2DATE OBSER\ED: SEPTEMBER 2, 2021 ELEVATON: LABORATORY TFST RFSU¿ß REMARKSDEPfH FEET s Y M B o L 5 A M P L E DESCRPNON OF MA|ERIAL AND SAMPLE LOCANON Topsoil w¡th roots Reddish-brown, blocky cloy WhitÍsh, sílty, gravelly sand, with volconÌc cobbles and boulders, colcoreou s, gypsìferous _15 _20 10 5 Refusol of 4 feet on bosolt boulders No Ground Woter Encountered - Bulk Somple - Noturol Dry Density (pcf) - Noturol Moisture Content - Percent Posslng No. 200 - Liquid Limit - Plostìcíty lndex - Ground woter (z) Sieve tlI DD MC -200 LL PI GW - 2-inch O.D. Colifornia Liner Somple I,EGEND: PK ECf fiO.:2t-3550SUBSURFACE EXPIORATION LOG nffiNa:2I,KP ENGINEERING, INC. Ã 4 z 2 o -l c.3 -2co a. l! -3 b\ -4 s .9Vttvr -¿ P a_ Eoo-6 -7 -8 -9 -,0 -11 -12 Swell - Consolìdotion Test ResultsEngÍnsælng,ila:J AWAY FROM BUILDING BACKFILL WITH A MINIMUM OF ONE FOOT OF RELATIVELY IMPERVIOUS SOIL GRANUI-AR F/{.1" TER FABRIC (MIRAFI 14ON OR EQUIVALENT) 3/4.INCH DIAIVETER, COARSE, CLEAN CRUSH ROCK 30 MIL MINIMUM THICKNESS,NCH DIAMETER PERFORATED PIPE SLOPED TO PLASTIC LINER, GLUED TO A DAYLIGHT LOCATION AWAY FROM THE FOUNDATION AT .I/4-INCH PER FOOI FOR FLEXIBLE AND 1/8.INCH IVfNIMUM FOR RIGID PIPE FOUNDATION WALL ¡ Þ rtollNt; Þ Þ Þ Þ Þ Þ ¡ Þ Þ \J s È \ :Iot- PERIMETER DRAIN CTVIL/GEOTECIÍNICAL 21-3550 scALE: N,f ,s. J90-OlO7 www.LKPEngineering.comlel t P.0. Box 724, Ecqle, C0 816J1 1OO2 SKIPPER DRIVE CARBONDALE GARFIELD COUNTY, COLORADO OVE REXCAVATI ON-STR UCTU RAL F I LL AND GEOGRID N.T.S, 5'mtn oulside MINUS 3/4.INCH CLEAN CRUSH ROCK (for under slab on grãde TËNâAR TriAx UND¡STURBED TXI 50 INUS 3-INCH ROAD BASE OR OTHER SUITABLE STRUCTURAL FI LL APPROVED BY THE ENGINEER NOTE: 1. EXCAVATE THE TOPSOIL AND OTHER UNSUITABTE SOIL 2. BACKFILL W|TH 6-INCHES OF STRUCTURAL F¡LL 3. CONSTRUCT THE FIRST LAYER OF IENSAR TTiAx GEOGR¡D OVER THE STRUCTURAL FILL 4 CONÎINUE WTH THE STRUCTURAL FILL AND TENSAR GEOGRID TO WITHIN 6.INCHES OF THE BOTTOM OF SLAB ON GRADE ELEVATION. 5, BACKFILL OVER THE LAST LAYER OF GEOGRID WITH 6-INCHES OF MINUS 3/4-INCH CLEAN CRUSH ROCK, 6. ANY SUBSTITUTIONS MUST BE VERIFIED WITH THE ENGINEER, rHE GEOGRID AND GEOTEXIILE PLACEMENT WILL BE ACCORDING TO THE MANUFACTURERS RECOMMENDATIONS, FOR STRUCTURAL FILL PLACEMENT OVEREXCAVATE: 4 FEET BELOW THE PROPOSED FOOTINGS ELEVAÏION 3 FEET BELOW THE PROPOSED SLAB ON GRADE ELEVATION SLAB ON GRADE I STRUCTURAL FILL WITH GEOGRID PROJECI NO 21 -3550LOT 1, STIRLING RANCH PUD CItrIL,/GEOTSCHNTCAL SCALf N.T S,IOO2 SKIPPER DRÍVE CARBONDALE GARFIELD COUNTY, COLORADO FIGURE ÑO 5 , comTel390- 0307 P.O. Box 724, íaqle, CO 81631