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Home My WebLink AboutSubsoils Report for Foundation DesignLKP Engineering, Inc. CIVILIGEOTECHMCAL SOI AND FOUNDATION INVESTIGATION F'OR A PROPOSED RESIDENCE LOT 32, ELK SPRTNGS, FTLTNG 6 A SUBDIVISION OF LOS AMIGOS RANCH PUD 38 WOODRUFF ROAD GLENWOOD SPRINGS GARFTELD COUNTY, COLORADO PROJECT NO. 2I.3497 MARCH 26,202I PREPARED FOR: RYAN IVY 2579 COANTY ROAD 115 GLENWOOD SPRTNGS, CO 81601 P.O. Box 724,Eagle, CO 81631 Tel. (970) 390-0307 www.LKPEngineerine.com 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...... UNDERDRAIN SYSTEM.... SITE GRADING AND DRAINAGE LAWN IRRIGATION ........... LIMITATION............ FIGURES LOCATION SKETCH. . SUBSURFACE EXPLORATION LOGS PERIMETER DRAIN DETAIL. STRUCTURAL FILL WITH GEOGRID . .DRAWING NO. 1 . .FIGURENO's 1-2 FIGURE NO. 3 . . FIGURE NO. 4 2 2 2 aJ aJ J 4 5 5 6 6 7 7 LKP Engineering,Inc. EXECUTIVE SUMMARY The proposed residence should be supported with conventional type spread footings, designed for an allowable soil bearing prsssure of 2000 psf. They should construct the footings on the undisturbed silty, sandy clay with basalt rocks or structural fill with geogrid. See X'oundation Recommendations. SCOPE OF STUDY This report presents the results of a subsurf'ace Soil and Foundation Investigation for a proposed residence to be constructed on Lot32, Elk Springs, Filing 6, A Subdivision of Los Amigos Ranch PUD, 38 Woodruff Road, Glenwood Springs, Garfield County, 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 hazqrd studies )are outside of our scope of services. SITE DESCRIPTION Lot32, Elk Springs Filing 6, A Subdivision of Los Amigos Ranch PUD is 2.285 acres and it is located at the southeast comer of the intersection of Los Amigos Drive and Woodruff Road, Glenwood Springs, Garfield County, Colorado. Vegetation within the proposed building site consisted of sparse grass, juniper trees, and sage brush. The topography was moderate with average slopes from about 10 to 15 percent. Drainage is to the southwest. Along the northwest property line was Woodruff Road. To the southwest was HOA vacant parcel. To the northeast of LKP Engineering,Inc. J the lot there was an existing residence. To the southeast was a vacant lot. Lot 32 was also vacant. PROPOSED CONSTRUCTION The soil and foundation investigation was done during the process of the lot purchase. Architectural plans have not been developed yet. We have assumed that the proposed residence will be two story, wood frame construction with a possible basement, on a concrete foundation, with an attached garage. We anticipate loads to be light, typical of residential construction. If the frnalizedplans differ significantly from the above understanding, they should noti$ us to reevaluate the recommendations of this report. FIELD INVESTIGATION The field investigation, conducted on March 20,202I, consisted of logging and sampling two test pits. The test pits were dug by you with Deere 60D trackhoe. 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 1 and2. Soil samples for laboratory soil analysis and observation were not taken due to the shallow refusal on basalt cobbles and boulders. SUBSURFACE SOIL AND GROUNDWATER CONDITION The soil profiles encountered in the two test pits were uniform, consisting of about a one to 1.5 feet of topsoil over whitish, calcareous, gypsiferous, silty, sandy clay with basalt rocks of gravel to cobbles and boulder size, cemented, to the maximum depth explored of 4 and 3 feet respectively. Ground water was not encountered in the test pits. LKP Engineering,Inc. 4 FOUNDATION 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 of the footings, can leave large voids and uneven subgrade. If the thickness of the leveling, structural fill is more than 6 to 8 inches, structural fiIl improved with Tensar geogrid, as shown on the attached detail, figure number 4, will be implemented. The completedfoundation excovation must be observed and tested by the undersigned engineer to verifu that the soil conditions encountered during construction are os anticipated in this report. 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 of at 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 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 l00Yo 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. 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 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. If during excavationfor the slab-on-grade similqr conditions, as described in the above foundation recommendations section, with large voids or uneven surface are created, structural fill as-describe above and as shown on the Structurol fill with geogrid detsil, figure number 4 will be used. The concrete slab should be constructed over a4-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 arelaterally 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 eafth, should be designed to resist an equivalent fluid density of 40 pcf for the "active" case. LKP Engineering,Inc. 6 The above design reconlmendations 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. 3). The foundation perimeter drain should consist of a 4-inch diameter, perforated pipe, sloped to a suitable gravrty 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 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 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 95o/o of the maximum standard Proctor density under pavement, sidewalk and patio areas and to at least 90%o of the maximum 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 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 I foot of relatively impervious filIto 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 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 LKP Engineering,Inc. 8 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 Ryan Ivy, for the specific application to the proposed residence on Lot 32,EIk Springs, Filing 6, A Subdivision of Los Amigos Ranch PUD, 38 Woodruff Road, Glenwood Springs, Garfield County, Colorado. Sincerely, LKP ENGINEERING,INC. LuizaPetrovska, PE -..."..''' i *i ^ ?sszli i *iffi*q@{r"",'l*:ii iii"t:. .' J:\ WP X4-LKP\ 2021\21 -3 497 CLAY- SAND-BASALT-PITS.DOCX LKP Engineering,Inc. ASnUnS V NO OfSVS rON Sr [fl-Vt{lXOUddV st Jd rsft fHt_ lo Notlvcol 3Hl- :3J-oN l{?1lT' ,* \lrg**:?H t€/'g dT l#? sgs . ,fr--- 1#-' {-" €ffiu $, 6&-'. qqp rye*'Q$ { -*"#y €3€Y #s JS? sfir *W,a,% Il f ? q *g \/ l^ fi I **ptr rY$ rfr J8?fir k /{0 //t .*-##-1h r** 3v st*tW =igzr roz * \ uroc'6upseul6ujd;'l'r/n^r ZOC0-O6g (01.6) pI ftgfg OC 'a16o3 'y72 xoE 'O'd 'cul 'Eurteaur7ug rvcrNucsrogc,/ttalc dXT HCJEXS NOIJVCOT oovuo-roc'I.tNnoc c']f HUVo scNluds oooMNSt9 'ovou llnuoooM 8e scNtuds vrf 'cnd HoNVU soctnv so] lo NotstN osns v'zc Io'lL6Vt-LZ : oN lSfroud ,09="1- ,!.lvcs , : oN oNtMw0 DATE OBSERVED: MARCH 20,2021 ELEVATION: Test Pit f L 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 with roots llhitish, colcoreous, glpsiferous, silty, sandy clay with bosalt rocks of gravel to cobbles and boulder size, cemented Refusal at 4 feet Ground Water Encountered I,EGEND: tr - 2-inch O.D. California Liner SompleI - Bulk SampleDD - Natural Dry Density (pcf) MC - Noturol Moisture Content (%) -200 - Percent Passing No. 200 SieveLL - Liquid LlmitPl - Plosticlty lndexCW - Ground water tKP ENGINEERING, INC.SUBSURFACE EXPLOMTION TOG PN),ECr NA:20-3497 Ifla)E NO,: DATE OBSERVED: MARCH 20,2021 ELEVATION: Test Pit f 2 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 X W Topsoil with roots over Vtlhitish, colcoreous, g1'psiferous, silty, sandy clay with basalt rocks of gravel, cobbles and boulder size Refusol at 3 feet Ground Water Encountered I,EGEND: tr - 2-inch O.D. Colifomio Liner SampleI - Bulk Somple DD - Natural Dry Density (pcf) MC - Natural Moisture Content (%) -200 - Percent Possing No. 200 SieveLL - Liquid LimitPl - Plasticity lndexGW - Ground water tKP ENGINEERING, INC.SUBSURFACE EXPTORATION tOG PROECT NO.:20-3497 nw ta:2 D .',FOONNG '.t D> {! S - R * R b' t PE AWAY FROM BUILDING R BACKFILL WITH A MINIMUM OF ONE FOOT OF RELATIVELY IMPERVIOUS SOIL ILTER FABRTC (MlRAFl 140N OR EOUIVALENT) INUS 3/4-INCH DIAMETER, COARSE, CLEAN CRUSH ROCK 30 MIL MINIMUM THICKNESS,NCH DIAMETER PERFORATED PIPE SLOPED TO PLASTIC LINER, GLUED TO TH 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 cMLlcEOTECUNICAL Engineering, Irtc. P.O. Box 724, Eogle, CO 81631 Tel (970) 590-0307 www.LKPEngineerinq.com LKP PERIMETER DRAIN LOT 32, A SUBDIVISION OF LOS AMIGOS RANCH PUD, ELK SPRINGS 38 WOODRUFF ROAD, GLENWOOD SPRINGS GARFIELD COUNTY, COLORADO PRo'rECt No': 21-g4g7 scALE: N.T.s. 3 HdJRE NO.: