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Home My WebLink AboutSubsoil StudyLKP Bngineering, Inc. CTVIL/GEOTECHNICAL RECEIVED jlJi- I t4 'llÅ:ì? GARFIELD COUNTY COMMUNITY DEVELOPMENT SOIL AI\D F'OI]IIDATION IIYVESTIGATION FORA PROPOSED RESIDENCE LOT 38, CERTSE RANCH SUBDryrSrON, PHASE 2 27 LARTGPUR DRTVE, CARBONDALE GARFTELD COUNTY, CO PROJECT NO. 20.3473 DECEMBER 9,2020 PREPARED tr'OR: SEAN & CHRISTINA DUFFY 5 ELEMENTS ELECTRIC INC. 2OO UTE TRAIL CARBONDALE, CO 81623 P.O. Box 724,Eagle, CO 81631 Tel (970) 390-0307 www.LKPEngineering.com SCOPE OF STUDY SITE DESCRIPTION. TABLE OF CONTENTS EXECUTIVE SUMMARY PROPOSED CONSTRUCTION..... FIELD INTVESTIGATION SUBSURFACE SOIL AND GROUNDWATER CONDITION FOUNDATION RECOMMENDATIONS ....... SLAB CONSTRUCTION RETAINING WALLS UNDERDRAIN SYSTEM SITE GRADING AND DRAINAGE LAWN IRruGATION........... LIMITATION............ FIGURES LOCATION SKETCH 2 2 2 3 3 3 4 5 5 6 6 7 7 .DRAWINGNO. 1 . FIGURE NO's 1-2SUBSURFACE EXPLORATION LOGS. GRAIN-SIZE DISTRIBUTION PERIMETER DRAIN DETAIL. . . . .FIGURE No's. 3-6 . . . .FIGURE NO. 7 LKP Engineering,Inc. 2 EXECUTTVE SUMMARY The proposed residence should be supported with conventional type spread footings, designed for an allowable soil bearing pressure of 1500 psf. They should construct the footings on the undisturbed silty-gravelly sand with some cobbles. See Foundation Recommendations. SCOPE OF'STT]DY This report presents the results of a subsurface Soil and Foundation Investigation for a proposed residence to be constructed on Lot 38, Cerise Ranch Subdivision, Phase 2,27 Lnkspur Drive, Carbondale, Garfield County, Colorado. The purpose of the subsurface soil and foundation investigation'$ras to determine the engineering characteristics of the foundation soil and to provide recoÍrmendations for the foundation design, grading, and drainage. Geologic hazard studies are outside ofour scope ofservices. SITE DESCRIPTION Lot 38 is a 4.152-acre lot on the north side of Larkspur Drive, about 850 feet west from the roundabout and the intersection with Bluestem Court, at27 Larkspur Drive in the Cerise Ranch Subdivision, Garfield County, Colorado. The lot variable moderate topography with a steep bank up from the road then moderate slope for the next 200 to 300 feet (or to the north LKP Engineering,Inc. 3 edge of the building envelope) and then steep slope again. The vegetation on the lot consisted of wild grass, cacti, shrubbery, cottonwood trees along the old irrigation ditch, and juniper trees on the upper, steep slopes. Drainage is to the south and southwest. Along the south side of the lot is Larkspur Drive. To the east and west are existing residences, and to the north arevacant lots of the White Cloud Subdivision. Lot 38 is also vacant. PROPOSED CONSTRUCTION We understand that the proposed residence will be a one story, wood frame construction on a concrete foundation, without a basement. \ile anticipate loads to be light, typical of residential construction. If the finalized.plans differ significantþ from the above understanding, they should notiff us to reevaluate the recommendations of this report. FIELD IIIVESTIGATION The field investigation, conducted on December 3,2020, consisted of excavating, logging and sampling two test pits. The excavation of the test pits was done with a John Deere 3lOSK, rubber tire bacftfioe. The test pits' locations are shown on Drawing No. 1. We show the soil profïle of the test pits on the Subsurface Exploration Logs, Figure No's I and2. Soil samples for laboratory soil anaþsis and observation were taken at selected intervals. Geologic hazard studies are outside of our scope of services. SUBSURFACE SOIL A¡ID GROUNDWATER CONDITION The soil profïles encountered in the two test pits were similar. Test Pit No. t had about one foot of topsoil over light brown, silty-clayey, sandy gravel with basalt and sandstone cobbles LKP Engineering,Inc. 4 and boulders over siþ-clayey, gravelly sand, calcareous with cobbles and few boulders, to the maximum depth explored of 8 feet. The soil was less gravelly in the last couple of feet. Test Pit No. 2 had about 1.5 feet of topsoil over of blocþ clay, over silty-gravelly sand, calcareous, gypsiferous with some, to the maximum depth explored of 8feet. Ground water was not encountered in either test pit. 'We sampled the soil in the test pits at random intervals. The soil samples were tested in our laboratory for natural moisture content and grain size distribution. The test results are shown on Figure No's 3 to 6. FOT]NDATION RECOMMENDATIONS The proposed residence should be supported with conventional type spread footings, designed for a maximum allowable soil bearing pressure of 1500 psf. The entire foundation should be constructed on the undisturbed siþ-gravelly sand with some cobbles. 'We recommend a minimum width of 16 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. 'We recommend a minimum of 48 inches of backfill cover for frost protection of the footing subsoils. Thefoundation excavation should be observed by the undersigned engineer to verify that the soil conditíons encountered during constructíon are as antícípated 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 l00o/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-698). A structural fill, placed under footings should be tested by a qualified professional on regular basis. LKP Engineering,Inc. 5 SLAB CONSTRUCTION The natural on-site soils, exclusive of topsoil and organics, are suitable to support lightþ 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 malenal, 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 a4-inch layer of clean gravel consisting of -3|4-inchgravel 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 control joints 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 \ryALLS Foundation walls retaining earth and retaining structures that arelaterally supported should be designed to resist an equivalent fluid density of 55pcf for an "at-rest" condition. Laterally unrestrained structures, retaining the on-site earth, should be designed to resist an equivalent fluid density of 35pcf for the "active" case. The above design recoÍrmendations assume drained backfill conditions and ahonzotttal LKP Engineering,Inc. 6 backfitl 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 400pcf 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 0.6. 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. I]NDERDRAIN SYSTEM To reduce the risk of surface water infiltrating the foundation subsoil, we recommend installation of a foundation perimeter drain (see Figure No. 7). The foundation perimeter drain should consist of a 4-inch diameter, perforated pipe, sloped to a suitable gravity outlet, or to a sump pump location, 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 filter fabric. The drain pipe should be covered with a minimum of 6 inches of -3l4-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 A}[D 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 90o/o of the ma¡rirnum standard Proctor LKP Engineering,Inc 7 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 recoÍrmended 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 I foot of relatively impervious fillto 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 10 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 option to test the soil with a backhoe pits verses with test borings drilled with a drill rig, was selected by you. There is no other warranty either expressed or implied. The findings and recoÍtmendations of this report are limited to the depth of the test pits investigated due to the type of equipment selected by the owner for the soils and foundation investigation. The above recoÍrmendations and based on field exploration, laboratory testing of LKP Engineering,Inc 8 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 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 Sean and Christina Dufff, for their proposed residence, to be constructed on Lot 38, Cerise Ranch Subdivision,Phase 2,27 Larkspur Drive, Carbondale, Garfield County, Colorado. Sincerely, LKP ENGINEERING,INC. \¿¿fr-;Ø*"h7-ù? LuizaPetrovska, PE J:\ WP X4-LKP\ 2020\20-34T3GRAVSNDPITS.DOCX LKP Engineering,Inc -tt\\ r-! u (ê '#-'c ) \ \l I t' I T ST \ g \B I I\{ I 6 l'- I I ¡ I I--.r I I I rÈsi ¡r ;;l;'lI It I'{ I i J- I I\ I i ¡ I I N I i È '--- \'t\'a '-. PIT. Irl f,t-.l ts è.qsa h:kìl\rg\mg \ ìl þ \ à\*t \ \ \_n\H\ \ l{''\l':lt, \"ìtr$ qêå Lì Ë u %j þð.r ' ¡ ..1 '1 I Ì t- L* ( '.- \ '?â>¡r I-l 197 t45.Ot -- -t--_--:--\*'-f------.-'\-l ,orle I I I I I .l I ¡ I ll o¿¡à I Ir.. l ì, I \ j I ,O/rg ¡ B f,o s\ s f) :+ è \ Lo ð. ß, È IR ññ ı¡r sl *"¡l '3u"t I ! ü lt{lt .s (o E l! ñ{ NoTE: THE LOCATION OF THE TÊST PITS lS APPROXIMATE. IT IS NOT BASED ON A SURVEY LOCATION SKETCH NÕ-:20-3473 -1"=50' NO.: 1 LOT 38, CERISE RANCH, PHASE 2 27 LARKSPUR DRIVE CARBONDALE GARFIELD COUNTY, COLORADO CIV¡L,/GEOTECITNICAL Engineering, Inc. P.O. Box 724' Eogle, CO 81631 LKP Tel 590-0307 DATE OBSERVED: DECEMBER 3, 2020 ELEVAÏON: Test Pit f 1 DEPTH FEET s Y M B o L s A M P L E DESCRPNON OF MATERIAL AND SAMPLE LOCANON LABORATORY TEST RESULIS REMARKS 5 _10 _15 _20 2V I I Topsoll, forest lltter ond heovy roots LÍght brown, sÌltycloyey, sandy grovel wlth cobbles and boulders, basolt ond sandstone over Sllt¡rclap¡1, gravelly sond, colcareous wlth cobbles and few boulders MC:4.1% -200=138 MC:5.52 -200:20.6% less grovelly neor the bottom Bottom of Test Pít at I feet No Ground l¡tlater Encountered I,EGEND: tr T DD MC - 2-ìnch O.D. CdlÍfomia LÍner Somple 200 - Bulk Sample - Notural Dry Density (pcf) - Noturdl MoÍsture Content - Percent Possìng No. 200 - LÍquld Llmit - PlastÍcíty lndex - Ground wdter (%) Sìeve LL PI GW IJ(P ENGINEERING, INC.SUBSURFACE EXPIORATION tOG PROECI lla.:20-3473 1 F'êUÊ No.' DATE OBSERVED: DECEMBER 5, 2020 ELEVAÏON: Test Pit ff 2 DEPTH 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 ^' I I Topsoil, dnd roots over blocky clay Tan, sllt¡rgravally sand, colcareous-glpslferous wlth some cobbles MC:5.3% -200:17.9% MC--5.22 -2OO=18.4% Bottom of Test Pìt of I feet No Around llater Encountered IEGEND: tr - 2-Ínch O.D. CalìfornÍo Llner SampleI - Bulk SampleDD - Natural Dry Densíty (pcf) MC - Notural Moisture Content (Z) -200 - Percent Passíng No. 200 SieveLL - Llquld LimitPl - PlastÍcíty lndexeW - Oround water tKP ENGINEERING, INC.SUBSURFACE EXPTORATION TOG PffiGCf NO.:20-3473 FIdJRE NO:2 ì$|aso$sIIsL=IaNÞøìùeoI(r¡FROM: Test Test PÍt 1 at 4 feetU.S. SIAIIDAH) STEUE æENN6 IN INC']æ U.S STAilDAH) SEVE MI'ÆRS6 1 3 2lrÈ I û ta t 3 I 6 ItO t1 ,6 Zt æA 50 70 ,(n tutO 2(nH'tÐRd,lFfEt1o102030ìonÈso$q60qFzog908070IS60G¡$uooI€+oFS .to20to8090îooo500100 50105I 0.5o.'t o.05o u)5o.æ1Sand: 5OZFînes: î3.0%\\\\\\-ll\\Sílt or ClaySondfìnemedîumcoarscGravelflnecootseCobblesMoìsture Content: 4.18Grovel: 372Descrìptîon: Sìtltyclo¡iey, grarelly Sand r$rosogsIf)ï=IaNÞfi)IaqìJPNoI(¡àdàFROM: Test Pít No. 1 ot 7 feetU.S SîAI,ITùM) SIEVE æÐüIE N NC'ß U.S STANDAN' SEVE NU,Æ€nS;6 13 2l,a I s ,ãû 3 1 6 ErO ,1 ,8 20 g'loæ 70rærØ2OOHVNüINERtooo90102030I,nåc)508ao609F709goı908070I$aoo*s50oI€+oFS .¡o2010otoo500IOO 50105't 05at o.o5o.oo5o.oolSond: 65.22\\\\\I\\\\\Sílt or ClaySandfrnemedlumcoarseGrovdfìnecoarsteCobblesMoisture Content: 5.58Grawl: 14.2ßDescrÍption: SÍltyclo¡oy, gravelly SandFînes: 20.62 o102030I40ä50i60qF709goı90100o.oo',o.oo5FROïI: Test Pít No. 2 ot 5 feetHVDRÆlRo.1 0.05u.s sTAì.tDM) gEtÆ rvul¿8Ens6 1t 2M I * ,aú J 1 6 8rO Ul6 n 5O,lO50 mlær,l0Z)Oî 0.5Sand: 64.8210sU.S SIATü,AH) S/ÆVE æøIINê IN INCI,ßtoo 50500't00908070I$60s$u,o€+oFS .ro2010o\\\\\\\\\\Sllt or CloySandfìnemedîumcoaftßGrovelflnecoarseCobblesFìnes: 1792DescrîptÍon: Sllty, gravelly SandGravd: 17.4ßMoÍsture Content: 5.32ì$roìogsspr=IñÞ(n*qIP(l o102030*&gsogìo60qF70s8090tu)o.oolo.oo5FROM: Iesf lest Pit 2 ot I feetHVNúßERaî o.o5U.S STA¡IDARD SEVE NUUffi6 1J 2ttÀ I * ûs. J 1 6 EIO ,1 l8 20 JOIOSO 70t(nr,r0Zn1 0.5105Sond: 58.42U.S STATIT'Afu SIEVE OPøINê N NCTIßtoo 50500908070IS60o¡$u,q€¡oFS .ro2010o\\\\\\\\\\Sîlt or CloySandfìnemedîumcoorsreGrovdfÍnecoarseCobbleeFines: 18.4O2DescrþtÍon: Sílty, gravelly SandGrovel: 23.22Moisture Content: 5.2ßì$|asogsII$IaNÞø*eIo=-EnFlsÈ"l* 'Á Þ ÞÞ Þ. Þ À Þ'' ! S È R= È U\_ AWAY FROM BUILDING BACKFILL WITH A MINIMUM OF ONE FOOT OF RELATIVELY IMPERVIOUS SOIL FABRTC (MtRAFr 140N OR EQUTVALENT) 3/4-INCH DIAMETER, COARSE, CLEAN CRUSH ROCK 30 MIL MINIMUM ÏHICKNESS,DIAMETER PERFORATED PIPE SLOPED TOPLASTIC LINER, GLUED TO A DAYLIGHT LOCAÏION AWAY FROM THE FOUNDATION AT 1/4-INCH PER FOOT FOR FLEXIBLE AND 1/8.INCH MINIMUM FOR RIGID PIPE FOUNDATION WALL cryrLlGEOTEcHNIcÂL Engineering, Inc. P.O. Box 724, Eogle, CO 81631 Tel (970) 390-0307 www.LKPEngineering.com LKP PERIMETER DRAIN LOT 38, CERISE RANCH, PHASE 2 27 LARKSPUR DRIVE CARBONDALE GARFIELD COUNTY, COLORADO PRoJEcr No.: 2O_g4Zg scALE: N,T.s, 7 |IçURL NO.: