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HomeMy WebLinkAboutSubsoils Report for Foundation DesignlGrtffi,ffifffi;;*x';*" An Employ;c Ourpd €*mFany 5020 County Road 154 Glenwood Springs, CO 81601 phone: (970) 945-7988 fax: (970) 945-8454 email : kaglenwood@Jcumarusa.com www.kumarusa.com Of,Ece Locations: Denver (HQ), Parker, Colorado Springs, Fort Collins, Glenwood Springs, and Summit County, Colorado SUBSOIL STUDY FOR FOUNDATION DESIGN PROPOSED ADDITION TO EXISTING RESIDENCE 131 BUCK POINT ROAI) LOT 7, PAI\ORAMA RANCHES GARFIELD COUNTY, COLORADO PROJECT NO.22-7-434 AUGUST 8,2022 PREPARED FOR: MATUSZESKI C/O BLACK SHACK ARCHITECTS P.O. BOX 1847 BASALT, COLORADO 81621 ATTN: GLENN RAPPAPORT grappa@blackshack.net TABLE OF CONTENTS PURPOSE AND SCOPE OF STUDY PROPOSED CONSTRUCTION ........... SITE CONDITIONS FIELD EXPLORATION SUBSURFACE CONDITIONS I -2- -2- DESIGN RECOMMENDATIONS FOLTNDATIONS FOUNDATION AND RETAINING WALLS FLOOR SLABS LINDERDRAIN SYSTEM SITE GRADING............... SUMACE DRAINAGE... LIMITATIONS........ FIGURE 1 - LOCATION OF EXPLORATORY BORING FIGURE 2 -LOG OF EXPLORATORY BORING FIGURE 3 - SWELL-CONSOLIDATION TEST RESULTS .....-2 - .....- 4 - .....- 4 - 2- 5- 5- ....- 6 - 1 -1- Kumar & Associates, lnc. @ Project No. 22-7-434 PURPOSE AI\D SCOPE OF STUDY This report presents the results of a subsoil study for a proposed addition to the existing residence located at l3l Buck Point Road, Lot7, Panorama Ranches, Garfield County, Colorado The project site is shown on Figure 1. The purpose of the study was to develop recommendations for the foundation design. The study was conducted in accordance with our proposal for geotechnical engineering services to Matuszeski c/o Black Shack Architects, dated June 17,2022. An exploratory boring was drilled to obtain information on the subsurface conditions. Samples of the subsoils obtained during the field exploration were tested in the laboratory to determine their classification, compressibility or swell and other engineering characteristics. The results of the field exploration and laboratory testing were analyzed to develop recommendations for foundation types, depths and allowable pressures for the proposed building foundation. This report summarizes the data obtained during this study and presents our conclusions, design recommendations and other geotechnical engineering considerations based on the proposed construction and the subsurface conditions encountered. PROPOSED CONSTRUCTION The proposed addition will be on the east side of the house and will be one story of wood frame construction over a crawlspace. Grading for the structure is assumed to be relatively minor with cut depths between about 2 to 3 feet. We assume relatively light foundation loadings, typical of the proposed type of construction. If building loadings, location or grading plans change significantly from those described above, we should be notified to re-evaluate the recommendations contained in this report. SITE CONDITIONS The site is occupied by the existing one-story, single-family residence. Access to the area of the proposed addition on the east side of the house was not possible due to the steep slope away from the house down to the east. Access to the southeast side of the house was not possible due to the existing leach field and fencing on the south side of the house. The house is on a south-trending ridge and the hillside is relatively steep sloping down to the east in the proposed addition area. Vegetation at the site consists of grass around the house and sage, juniper and pinyon trees in the area east ofthe house. Kumar & Associates, lnc. @ Project No. 22-7-434 -2- F'IELD EXPLORATION The field exploration for the project was conducted on July 19, 2022. One exploratory boring was drilled at the location shown on Figure I to evaluate the subsurface conditions. The boring was advanced with 4-inch diameter continuous flight augers powered by truck-mounted CME- 458 drill rig. The boring was logged by a representative of Kumar & Associates, Inc. Samples of the subsoils were taken with 1%-inch and 2 inch I.D. spoon samplers. The samplers were driven into the subsoils at various depths with blows from a 140 pound hammer falling 30 inches. This test is similar to the standard penetration test described by ASTM Method D-1586. The penetration resistance values are an indication of the relative density or consistency of the subsoils. Depths at which the samples were taken and the penetration resistance values are shown on the Log of Exploratory Boring, Figure 2. The samples were returned to our laboratory for review by the project engineer and testing SUBSURFACE CONDITIONS A graphic log of the subsurface conditions encountered at the site is shown on Figure 2. The subsoils consist of about I foot of gravelly sand and clay fill overlying 5 feet of stiff, silty sandy clay. Below the clay, at a depth of 6 feet, relatively dense, clayey sandy basalt gravel and cobbles was encountered down to the bottom of the boring at 16 feet. Laboratory testing performed on samples obtained from the boring included natural moisture content, density and percent finer than sand size gradation analyses. Results of swell- consolidation testing performed on a relatively undisturbed drive sample of the sandy silty clay, presented on Figure 3, indicate low compressibility under conditions of loading and wetting and a minor expansion potential when wetted under a constant light surcharge. No free water was encountered in the boring at the time of drilling and the subsoils were slightly moist. DESIGN RECOMMENDATIONS FOUNDATIONS Considering the subsurface conditions encountered in the exploratory boring and the nature of the proposed construction, we recommend the building addition be founded with spread footings bearing on the natural sandy soils below any existing fill and topsoil. The design and construction criteria presented below should be observed for a spread footing foundation system. l) Footings placed on the undisturbed natural soils should be designed for an allowable bearing pressure of 1,500 psf. Based on experience, we expect Kumar & Associates, lnc. o Project No.22-7-434 aJ 3) settlement of footings designed and constructed as discussed in this section will be about I inch or less. The footings should have a minimum width of 16 inches for continuous walls and 2 feetfor isolated pads. Exterior footings and footings beneath unheated areas should be provided with adequate soil cover above their bearing elevation for frost protection. Placement of foundations at least 36 inches below exterior grade is typically used in this area. --r Continuous foundation walls should be reinforced top and bottom to span local anomalies such as by assuming an unsupported length of at least 10 feet. Foundation walls acting as retaining structures should also be designed to resist lateral earth pressures as discussed in the "Foundation and Retaining Walls" section of this report. All existing fill, topsoil and any loose or disturbed soils should be removed and the footing bearing level extended down to the relatively dense natural soils. The exposed soils in footing area should then be moistened and compacted. A representative of the geotechnical engineer should observe all footing excavations prior to concrete placement to evaluate bearing conditions. 4) 6) FOLINDATION AND RETAINING WALLS Foundation walls and retaining structures which are laterally supported and can be expected to undergo only a slight amount of deflection should be designed for a lateral earth pressure computed on the basis of an equivalent fluid unit weight of at least 55 pcf for backfill consisting of the on-site clay soils. Cantilevered retaining structures which are separate from the residence and can be expected to deflect sufficiently to mobilize the full active earth pressure condition should be designed for a lateral earth pressure computed on the basis of an equivalent fluid unit weight of at least 45 pcf for backfill consisting of the on-site clay soils. All foundation and retaining structures should be designed for appropriate hydrostatic and suicharge pressures such as adjacent footings, traffic, construction materials and equipment. The pressures recommended above assume drained conditions behind the walls and a horizontal backfill surface. The buildup of water behind a wall or an upward sloping backfill surface will increase the lateral pressure imposed on a foundation wall or retaining structure. An underdrain should be provided to prevent hydrostatic pressure buildup behind walls. Backfill should be placed in uniform lifts and compacted to at least 90%o of the maximum standard Proctor density at a moisture content near optimum. Backfill in pavement and walkway areas should be compacted to at least 95Yo of the maximum standard Proctor density. Care 2) 5) Kumar & Associates, lnc. @ Project No.22-7-434 -4- should be taken not to overcompact the backfill or use large equipment near the wall, since this could cause excessive lateral pressure on the wall. Some settlement of deep foundation wall backfill should be expected, even if the material is placed correctly, and could result in distress to facilities constructed on the backfill. Backfill should not contain organics, debris or rock larger than about 6 inches. The lateral resistance of foundation or retaining wall footings will be a combination of the sliding resistance of the footing on the foundation materials and passive earth pressure against the side of the footing. Resistance to sliding at the bottoms of the footings can be calculated based on a coefficient of friction of 0.35. Passive pressure of compacted backfill against the sides of the footings can be calculated using an equivalent fluid unit weight of 300 pcf. The coefficient of friction and passive pressure values recommended above assume ultimate soil strength. Suitable factors of safety should be included in the design to limit the strain which will occur at the ultimate strength, particularly in the case of passive resistance. Fill placed against the sides of the footings to resist lateral loads should be a granular material compacted to at least 95%o of themaximum standard Proctor density at a moisture content near optimum. FLOOR SLABS The natural on-site soils, exclusive of topsoil, are suitable to support lightly loaded slab-on-grade construction. To reduce the effects of some differential movemento floor slabs should be separated from all bearing walls and columns with expansion joints which allow unrestrained vertical movement. Floor slab control joints should be used to reduce damage due to shrinkage cracking. The requirements for joint spacing and slab reinforcement should be established by the designer based on experience and the intended slab use. A minimum 4 inch layer of free- draining gravel should be placed beneath basement level slabs to facilitate drainage. This material should consist of minus 2-inch aggregatewith at least 50% retained on the No. 4 sieve and less than2o/o passing the No. 200 sieve. All fill materials for support of floor slabs should be compacted to at least 95Yo of maximum standard Proctor density at a moisture content near optimum. Required fill can consist of the on- site granular soils or a suitable imported gravel, such as '/o inch road base, devoid of vegetation, topsoil and oversized rock. LINDERDRAIN SYSTEM Although free water was not encountered during our exploration, it has been our experience in mountainous areas that local perched groundwater can develop during times of heavy precipitation or seasonal runoff. Frozen ground during spring runoff can create a perched condition. We recommend below-grade construction, such as retaining walls, crawlspace and Kumar & Associates, lnc. @ Project No. 22-7-434 5 basement areas? be protected from wetting and hydrostatic pressure buildup by an underdrain system. The drains should consist of drainpipe placed in the bottom of the wall backfill surrounded above the invert level with free-draining granular material. The drain should be placed at each level of excavation and at least 1 foot below lowest adjacent finish grade and sloped at a minimum lYoto a suitable gravity outlet. Free-draining granular material used in the underdrain system should contain less than 2%o passingthe No. 200 sieve, less than 50olo passing the No. 4 sieve and have a maximum size of 2 inches. The drain gravel backfill should be at least lYz feet deep. SITE GRADING The risk of construction-induced slope instability at the site appears low provided the addition is located above the steep slope as planned and cut and fill depths are limited. We assume the cut depths for the foundation level will not exceed one level, about 4 to 6 feet. Fills should be limited to about 8 to l0 feet deep, especially at the downhill side of the residence where the slope steepens. Embankment fills should be compacted to at least95o/o of the maximum standard Proctor density near optimum moisture content. Prior to fill placement, the subgrade should be carefully prepared by removing all vegetation and topsoil and compacting to at least 95o/o of the maximum standard Proctor density. The fill should be benched into the portions of the hillside exceeding 20%o grade. Permanent unretained cut and fill slopes should be graded at 2 horizontal to I vertical or flatter and protected against erosion by revegetation or other means. The risk of slope instability will be increased if seepage is encountered in cuts and flatter slopes may be necessary. If seepage is encountered in permanent cuts, an investigation should be conducted to determine if the seepage will adversely affect the cut stability. SURFACE DRAINAGE The following drainage precautions should be observed during construction and maintained at all times after the addition has been completed: l) Inundation ofthe foundation excavations and underslab areas should be avoided during construction. 2) Exterior backfill should be adjusted to near optimum moisture and compacted to at least 95%o of the maximum standard Proctor density in pavement and slab areas and to at least 90o/o of the maximum standard Proctor density in landscape areas. 3) The ground surface surrounding the exterior of the building should be sloped to drain away from the foundation in all directions. We recommend a minimum slope of 12 inches in the first 10 feet in unpaved areas and a minimum slope of Kumar & Associates, lnc. @ Project No.22-7-434 -6- 4) 3 inches in the first 10 feet in paved areas. Free-draining wall backfill (if any) should be covered with filter fabric and capped with about 2 feet af the on-site soils to reduce surface water infiltration. Roof downspouts and drains should discharge well beyond the limits of all backfill. LIMITATIONS This study has been conducted in accordance rvith generally accepted geotechnical engineering principles and practices in this area at this time. We make no warranty either express or implied. The conclusions and recommendations submitted in this report are based upon the data obtained from the exploratory boring drilled at the iocation indicated on Figure 1, the proposed type of construction and our experience in the area. Our services do not inciude determining the presence? prevention or possibility of mold or other biological cantaminants {MOBC) developing in the future. If the client is concerned about MOBC, then a professional in this special field of practice should be consulted. Our findings include interpolation and extrapolation of the subsurface conditions identilied at the exploratcry boring and variations in the subsurface conditions rnay not become evident until excavation is performed. If conditions encountered during ccnstruction appear different from those described in this report, we should be notified so that re-evaluation of the reccmmendations may be made. This report has been prepared for the exclusive use by our client for dssign pu{poses. We are not responsible for technical interpretations by othsrs of our infarrnation. As the project evolves, we should pravide continued ccnsultation and field services during constructian to review and monitor the inrplernentation of our recommendations, and to veriry that the recommendations have been appropriately interpreted. Significant design changes may require additional analysis or modifications to the recommendations presented herein. We reccmmend on-site observation of excavations and foundation bearing strata and testing of structural fill by a representative of the geotechnical engineer Respectfu I ly Submitted, Kermav & Asso*ta€eso Daniel E. Hardin, Rev. by: SLP DEHlkac n{(}ij,& 24f[t Kum*r & As*ociates, lnc. ei Frcject No. 22-7"434 € /, I HOMESTEAD 7 131 BUCK POINT ROAD I 1 30 /APPROXIMATE SCALE-FEET 22-7-434 Kumar & Associates LOCATION OF EXPLORATORY BORING Fig. 1 t $ ff: BORING 1 EL. 7299' 0 FILL; SAND AND CLAY WITH GRAVEL, FIRM, SLIGHTLY MO|ST, BROWN. CLAY (CL): SANDY, SILTY, VERY STIFF T0 HARD, SLIGHTLY MotsT, BRoWN, TRACE CALCAREoUS. 5 11/12 WC=9.8 BASALT GRAVEL AND CoBBr.fS (GC) SUGHTLY MOIST, BROWN, SUGHTLY SANDY, CI,AYEY, DENSE, CALCAREOUS. DD=1 1 6 -200=55 F i DRIVE SAMPLE, 2-INCH I.D. CAUFORNIA LINER SAMPI."E. F UJ UJ l! I-F(L UJo 10 8s/11 DR|VE SAMPLE, 1 S/8-|NCH r.D. SPL|T SP00N STANDARD PENETRATION TEST. 4712DRIVE SAMPLE BL0W COUNT. INDICATES THAT 44 BLOWS 0F,'I '- A 140-POUND HAMMER FALTING 30 INCHES WERE REQUIRED TO DRIVE THE SAMPLER 12 INCHES. 15 38/12 WC=9.6 -200=65 NOTES 1. THE EXPLORATORY BORING WAS DRILLED ON JULY 19, 2022 IYITH A 4-INCH DIAMETER CONTINUOUS FLIGHT POWER AUGER. 20 2, THE LOCATION OF THE EXPLORATORY BORING WAS MEASURED APPROXIMATELY BY PACING FROM FEATURES SHOWN ON THE SITE PI.AN PROVIDED. 3. THE ETTVATION OF THE EXPLORATORY BORING WAS OBTAINED BY INTERPOLATION BENVEEN CONTOURS ON THE SITE PLAN PROVIDED. 4. THE EXPLORATORY BORING TOCATION AND ELEVATION SHOULD BE CONSIDERED ACCURATE ONLY TO THE DEGREE IMPLIED BY THE METHOD USED. 5. THE LINES BETWEEN MATERIALS SHOWN ON THE EXPLORATORY BORING LOG REPRESENT THE APPROXIMATE BOUNDARIES BENYEEN MATERIAL TYPES AND THE TRANSITIONS MAY BE GRADUAL. 6. GROUNDWATER WAS NOT ENCOUNTERED IN THE BORING AT THE TIME OF DRILLING. 7. LABORATORY TEST RESULTS: WC = WATER O0NTENT (x) (ASTM D 2216); DD = DRY DENSITY (PCf) (ISTV D 2216); -200 = PERCENTAGE PASSING N0. 200 SIEVE (ASTM D 1140). Fis. 222-7 -434 Kumar & Associates LOG OF EXPLORATORY BORING SAMPLE OF: Sondy Silty Cloy FROM:BoringlO5' WC = 9.8 %, DD = 116 pcf -2OO = 55 % EXPANSION UNDER CONSTANT PRESSURE UPON WETTING t-- ) \ ont l.d. hrftD-4546. 1 )s JJIJ =a I z.o F o =o anzo(J o -1 -2 - KSF 't0 i00 22-1 -434 Kumar & Associates SWELL-CONSOLIDATION TEST RESULTS Fig. 3 qpublic.net - Garfield County, CO - Property Record Card: R011092 https://qpublic.schneidercorp.com/Application.aspx?ApplD=103. GlqFrklic,nef- Garfield County, CO Summary Account Parcel Property Address Legal Description Acres Land SqFt Tax Area Mill Levy Subdivision R011092 239177r070o7 131 BUCK POINT RD,CARBONDALE, CO 81623 Section: lTTomship:7 Range: 87 SuMivision: PANORAMA RANCHES HOMESTEAD 7 5.12 ACRES 5.119 0 7t 81.0290 PANORAMA RANCHES lriew l.4ro Owner MATUSZESKI, JOHN ANDREW & STEWARD, CHERY 131 BUCK POINT ROAD CARBONDALE CO 81623 Land UnitType Square Feet Buildings Building# Units BuildingType Abstract Codes / (PropefiType) Architectural Style Stories Frame Actual Year Built Gross Living Area Total Heated SqFt Bedrooms Baths Heating Fuel Heating Type AirConditioning RoofType Roof Cover Actual Values Assessed Year SINGLE FAM.RES..LAND - 1112 (RESIDENTIAL PROPERTY) 0 t 7 SFR SINGLE FAM.RES-IMPROVEMTS-1212 (RESIDENTIAL PROPERTY) 1-STORY 7 WOOD FRAME 7991- 7,477 1,477 a 2 GAS HTWTR RAD NONE RIDGE FRME PREFAB MET 2023 20zt 2027 $47s,000.00 $200,000.00 $200,000.00La-ld Actlal lmprovement Actual $588,230.00 $419,450.00 $419,450.00 Total Actual Assessed Values Assessed Year $1,063,230.00 $619,450.00 $619,450.O0 2023 2022 2021 Land Assessed $33,010.00 $13,900.00 $14,3O0.00 $40,880.00 $29,1s0.00 $29,990.00lmprovement Assessed Total Assessed Tax History Tax Year 2022 Taxes Billed $3,488.28 $73,890.00 $43,050.00 w290.oo 2027 2020 20L9 $3,078.84 1of 3 Clici< here io l:iewtlre tax information for ihis Farcel on tte Garfiel{i Covniv n:e asulrer's we bsite $3,533.28 $3,Os1.72 5n12023,2:45PM qPublic.net - Garfield County, CO - Property Record Card: R011092 https:i/qpublic.schneidercorp.com/Application.aspx?ApplD=103... Transfers Sale Date Deed Typ€Book - Page Sale Price at2,/202L a/2/2021 PERSONA-L REP DEED STATEMENT OF AUTHORITY ?6Q94r _ 950940 $85s,000 9,0 Tlel?o_21 5tt/202L COVENANTS LETTERS .26S_e-3?$o 956397 $o $o2/70/2027 DEATH CERTIFICATE 960?3E 4/7/2020 3/17/2020 WARRANWDEED POWER OF ATTORNEY 933757 $750,000 $o $o1!,17129t6 5/21/2007 s/21/2007 RESOLUTION AFFIDAVIT gge-1gg 724005 7929-0526 $o WARRANryDEED 724A42 7929-0505 $654,000 5/76/2@7 sll/teeg 2/24t7987 POWEROFAfiORNEY WARRANryDEED CONTRACT 7?4003 414327 1929-0506 o773-0722 o56A-0422 $49,000 $o $o to/70,17979 SUBDIVISION IMPROVEMENTS 2eB-3.91 0536-0878 $o 8/30t1979 COVENANTS Property Related Public Documents f ljck ttere io vi€w Prope|Ly-8glglgd&lblSpSgllretl9 Photos Sketches ,sA2A.9 0536-0799 $o 2of3 5n2023,2:45PM qpubtic.net - Garfield County, CO - property Record Card: R011092 https://qpublic.schneidercorp.com/Application.aspx?ApplD=103. :S' ONE 1477 st ee{FGR 624 s{ 2S st The Garfield county Assessor's office makes wery effort to produce the most accurate information possible. No warranties, expressed or implied are provided forthe data herein, its use or interpretaiion, Data is subject to constant change and its accuracy and completeness cannot be guaranteed. User Privacv Policy. GDPR Privacv Notice Last Data tJ0lgAcLi!512Q23-$:31:15 PM Verslon 3'1'7 Developed by {-}ffilHs 3of3 5nD023,2:45PM GlqFshlic.net* Garfield County, Co Overview Legend I Parcets Roads Parcel/Account Numbers OwnerName Address i:J TaxDistricts CountyZoning Ei:q ^^l:..r* Lu - Commercial/General J crw- lncorporated City orTown il cL- Commercial/Limited i-] l- lndustrial f1ff pn- PublicAirport lij el-euutictands L] euo - errnned Unit Development I n-nurat i l nl-Rutort." Lands i -i nvnp- Residential/Mobile Home Park i*-i ns - Residential/Suburbar * nu- Residential/Urban il 'all other valuesr ffi Lakes&Rivers fficiti.t * CountyBoundary Line Date created: 517 /2Q23 Last Data Uploaded: 5/ 5/2O23 !0:31:75 PM Deveroped bvlF;i) *tl*n Sfl GlqPrrhliE.nst* Garfield County, Co 131 BUCK POINT RD CARBONDALE MATUSZESKI, JOHN ANDREW & STEWARD,CHERY 131 BUCK POINT ROAD CARBONDALE CO 81623 2O19Total ActualValue Overview Legend Parcels Roads Parcel/Account Numbers OwnerName i€ Lakes & Rivers * CountyBoundary Line $1,063,230 Last2Sales Date Price aa2o2t $855,000 4/U2020 $7s0,000 Account Number Parcel Number Acres Land SqFt Tax Area 2019 Mill Levy R011092 239717LO\OO7 5 0 011 81.0290 Physical Address Owner Address 81623 Datecreated:517/2O23 Last Data Uploaded: 5 15 / 2023 !O.3Lt15 PM Dweroned bv{i1) ffit;$?drt GlqFuhllc,n€** Garfield County, co 131BUCK POINTRD CARBONDALE MATUSZESKI, JOHN ANDREW & STEWARD,CHERY 131BUCK POINT ROAD CARBONDATE CO8t623 2019Total Actual Value Overview Legend [-*l Parcels Roads Parcel/Account Numbers OwnerName i.1j Lakes & Rivers * CountyBoundary Line $1,063,230 Last2Sales Date Price 8/A2O27 $855,000 4/U2020 $750,000 Account Number Parcel Number Acres Land SqFt Tax Area . 2019 Mill Levy R011092 239tt7tOtOO7 Physical Address Owner Address 8t623 5 0 0 8 tt 7.O290 Date created:5/7 /2O23 Last Data Uploaded: 5 /5 / 2O23 70133:.!5 PM Deverooedbvlpl)ffigd*r