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Home My WebLink AboutSubsoil Study for FoundationlGrtiiffififfi:ffini'íy;-* An Employcc Orncd Compony 5020 County Road 154 Glenwood Springs, CO 81601 phone: (970) 945-7988 fax: (970) 945-8454 email : kaglenwood@kumarusa.com www.kumarusa.com Office Locations: Denver (HQ), Parker, Colorado Springs, Fort Collins, Glenwood Springs, and Summit County, Colorado SUBSOIL STUDY FOR FOUNDATION DESIGN PROPOSED RESIDENCE AND ADU LOT 52, CERTSE RANCH 360 CERISE RANCH ROAI) GARFIELD COUNTY, COLORADO PROJECT NO.2t-7-249 JULY 21,2021 PREPARED FOR: GLYNNA BAKER P.O. BOX 5748 FRTSCO, COLORADO 80443-5748 qlvnna@slvnnabaker.com TABLE OF CONTENTS PURPOSE AND SCOPE OF STUDY ..._1_ PROPOSED CONSTRUCTION ....- 1 - SITE CONDITIONS I SUB SIDENCE POTENTIAL ................-2- SUBSURFACE CONDITIONS ....- 3 - FOUNDATION BEARING CONDITIONS -J- DESIGN RECOMMENDATIONS ...- 4 - ...- 4 -FOUNDATIONS ....... FOUNDATION AND RETAINING \MALLS ................- 4 - FLOOR SLABS ........- 5 - UNDERDRAIN SYSTEM LIMITATIONS .....- 8 - FIGURE 1 . LOCATION OF EXPLORATORY BORINGS FIGURE 2 - LOGS OF EXPLORATORY BORINGS FIGURE 3 - LEGEND AND NOTES FIGURE 4 - SWELL-CONSOLIDATION TEST RESULTS FIGURES 5 and 6 - GRADATION TEST RESULTS TABI,E I. SIII\4MARY OF T,ABORATORY TEST RESIIT,TS .............- 6 - Kumar & Associates, lnc. o Project No. 21-7-249 PURPOSE AND SCOPE OF STUDY This report presents the results of a subsoil study for a proposed residence and ADU to be located at Lot 52, Cerise Ranch, 360 Cerise Ranch Road, 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 supplemental to our agreement for geotechnical engineering services to Glynna Baker dated March 5,2021. We previously conducted a geotechnical review of the subject site for driveway and utilities and presented our findings in a report dated March 17, 2021, Project No. 2l -7 -249 . A field exploration program consisting of exploratory borings was conducted 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 analyzedto 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 main residence will be a two or three-story structure over a walk-out basement level with an attached garage. The proposed ADU will be a one or two-story structure over a walk-out basement level. Ground floors will be slab-on-grade. Grading for the structures is assumed to be relatively minor with cut depths between about 5 to 10 feet. An asphalt paved driveway is proposed to access the proposed building sites from the southwest and along the existing rough graded road from Cerise Ranch Road. 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 subject site is currently vacant. There is a rough graded road that accesses the building area along the southem property line from Cerise Ranch Road and climbs up around to the north Kumar & Associates, lnc. o Project No.2l-7-249 -2- along the western property line. Topography at the site consists of hillside terrain with slopes around 10 to 20 percent in the area of the proposed driveway, residence, and ADU. Slopes of up to about 60 percent are present on the lot north ofthe building areas not planned for development. Vegetation at the site consists of native grass and weeds, sage brush, juniper, and pinon. SUBSIDENCE POTENTIAL Bedrock of the Pennsylvanian age Eagle Valley Evaporite underlies the subject site. These rocks are a sequence of gypsiferous shale, fine-grained sandstone and siltstone with some massive beds of gypsum and limestone. There is a possibility that massive gypsum deposits associated with the Eagle Valley Evaporite underlie portions of the lot. Dissolution of the gypsum under certain conditions can cause sinkholes to develop and can produce areas oflocalized subsidence. During previous work in the area, several sinkholes were observed scattered throughout the Cerise Ranch development. These sinkholes appear similar to others associated with the Eagle Valley Evaporite in areas of the lower Roaring Fork River valley. Sinkholes were not observed in the immediate area of the subject lot. No evidence of cavities was encountered in the subsurface materials; however, the exploratory borings were relatively shallow, for foundation design only. Based on our present knowledge of the subsurface conditions at the site, it cannot be said for certain that sinkholes will not develop. The risk of future ground subsidence in the development area of Lot 52 throughout the service life of the proposed residence, in our opinion, is low; howevero the owner should be made aware of the potential for sinkhole development. If further investigation of possible cavities in the bedrock below the site is desired, we should be contacted. FIELD EXPLORATION The flteld exploration for the proj ect was conducted on June 1 7, 202 1 . Six exploratory borings were drilled at the locations shown on Figure 1 to evaluate the subsurface conditions. The borings were advanced with 4 inch diameter continuous flight augers powered by a track- mounted CME 45 drill rig. The borings were logged by a representative of Kumar & Associates, Inc. Sanrples of the subsoils were taken with 1% inoh 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-l586 The penetration resistance values are an indication of the relative density or consistency of the Kumar & Associates, lnc. o Project No.21-7-249 -J- subsoils. Depths at which the samples were taken and the penetration resistance values are shown on the Logs of Exploratory Borings, Figure 2. The samples were returned to our laboratory for review by the project engineer and testing. SUBSURFACE CONDITIONS Graphic logs of the subsurface conditions encountered at the site are shown on Figure 2. lnfhe area of the proposed main residence and ADU (Borings 1 -3), the subsoils consist of up to lz leet of topsoil overlying up to 5 feet of sandy silty clay underlain by basalt boulders, cobbles, and gravel in a sandy silt matrix down to the maximum depth explored of 19 feet. Drilling in the coarse granular soils with auger equipment was difficult due to the cobbles and boulders and drilling refusal was encountered in the deposit at a depth of l8 feet in Boring 2 and 6% feet in Boring 3 . In the area of the proposed driveway (Borings 4-6) the subsoils consist of 3 to 4 inches of road base overlaying slightly sandy clayey basalt gravel cobbles and boulders. In Boring 4, about 4%feúof sandy clay and silt was encountered between the road base and the clayey gravel. Laboratory testing performed on samples obtained from the borings included natural moisture content and density, Atterberg limits, and gradation analyses. Results of swell-consolidation testing performed on a sample of the sandy silt matrix material, presented on Figure 4, indicate moderate to high compressibility under conditions of loading and wetting. Results of gradation analyses performed on small diameter drive samples (minus lYz-inch fraction) of the coarse granular subsoils are shown on Figures 5 and 6. The laboratory testing is summarized in Table 1. No free water was encountered in the borings at the time of drilling and the subsoils were slightly moist. FOUNDATION BEARING CONDITIONS The subsoils encountered on the lot generally consist of basalt gravel cobbles and boulders in a sandy silt matrix. The upper silt and clay soils are low density and are typically known to be compressible when wetted under load. Lightly loaded spread footings can be used for support of the proposed residence provided that a risk of settlement and distress is acceptable to the owner. Removing the silt and clay soils and placing the footings on a depth (typically 2 to 3 feet) of compacted structural fill could be used to reduce the risk of settlement. Kumar & Associates, lnc. o Project No. 21-7-249 4 DESIGN RECOMMENDATIONS FOUNDATIONS Considering the subsurface conditions encountered in the exploratory borings and the nature of the proposed construction, we recommend the building be founded with spread footings bearing on the natural granular soils, beneath the upper fine-grained soils or compacted structural fill placed on the natural granular soils. The design and construction criteria presented below should be observed for a spread footing foundation system. 1) Footings placed on the undisturbed natural granular soils or compacted structural fill should be designed for an allowable bearing pressure of 2,000 psf. Based on experience, we expect initial settlement of footings desjgkãætructed as discussed in this section will be about I inch or less. If the bearing soils were to become wetted, additional settlement up to around I inch could occur depending mainly on the depth and extent of wetting. 2) The footings should have a minimum width of 20 inches for continuous walls and 2 feet for isolated pads. 3) 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 alea. 4) Continuous foundation walls should be heavily reinforced top and bottom to span local anomalies such as by assuming an unsupported length of at least 14 feet. Foundation walls acting as retaitritrg structurcs slroulcl also be designed to resist lateral earth pressures as discussed in the "Foundation and Retaining Walls" section of this report. 5) The topsoil, fine grained soils and any loose or disturbed soils should be removed and the footing bearing level extended down to the relatively dense natural granular soils. The exposed soils in frroting nren shoulcl thcn bc moistcncd ancl compacted. 6)@itãi1Te."ofthegeotechnicalengineershouldobserveallfooting cxcavations prior to concrete placement to evaluate bearing conditions. 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 eafth pressure Kumar & Associates, lnc. o Project No. 21-7-249 -5- computed on the basis of an equivalent fluid unit weight of at least 50 pcf for backfill consisting of the on-site soils. Cantilevered retaining structures which are separate from the residence or ADU 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 soils. Backfill should not contain organics or rock larger than 6 inches. All foundation and retaining structures should be designed for appropriate hydrostatic and surcharge pressures such as adjacent footings, traffic, construction materials and equipment. The pressures recommended above assume drained conditions behind the walls and a horizontal backfîll 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 90o/o of tbe maximum standard Proctor density at a moisture content near optimum. Backfill placed in pavement and walkway areas should be compacted to at least 95%o of the maximum standard Proctor density. Care 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. 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 0.40. Passive pressure of compacted backfill against the sides of the footings can be calculated using an equivalent fluid unit weight of 350 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 95o/o of the maximum 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 with a risk of settlement if the bearing soils are wetted. To reduce the effects of Kumar & Aseociates, lnc. o Project No. 21-7-245 -6- some differential movement, 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 bc cstablished 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 aggregate with at least 50% retained on the No. 4 sieve and less than 2Yo passing the No. 200 sieve. All fill materials for support of floor slabs should be compacted to at leastg5o/o of maximum standard Proctor density at a moisture content near optimum. Required fill can consist of the on- site soils devoid of vegetation, topsoil and oversized rock. UNDERDRAIN SYSTEM Although free water was not encountered during our exploration, it has been our experience in the area 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 basement areas, be protected from wetting and hydrostatic pressure buildup by an underdrain system. The drains should consist of PVC 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 lYo to a suitable gravity outlet. Free-draining granular material used in the underdrain system should contain less than 2o/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 I%feef deep and covered with filter fabric such as Mirafi 140N or 160N. An impervious membrane such as 20 or 30 mil PVC should be placed beneath the drain gravel in a trough shape and attached to the foundation wall with mastic to prevent wetting of the bearing soils. SITE GRADING The risk of construction-induced slope instability at the site appears low provided the buildings are located as planned and cut and fill depths are limited. We assume the cut depths for the basement lcvcls will not exceed one level, about l0 to 12 feet. Fills should be limited to about I tu 10 fcct dccp, cspccially at thc downhill side of the rcsidcnce ,¡r ADU where thc slupe steepens. Embankment fills should be compacted to at leastg5o/o of the maximum standard Kumar & Associates, lnc. o Project No. 21-7-249 -7 - 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 95%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 at2horizontal to 1 vertical or flatter and protected against erosion by revegetation or other means. This office should review site grading plans for the project prior to construction. SURFACE DRAINAGE The following drainage precautions should be observed during construction and maintained at all times after the residence and ADU have been completed: 1) 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%ó of the maximum standard Proctor density in pavement and slab areas and to at least 90Yo 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 3 inches in the first 10 feet in paved areas. Free-draining wall backfill should be covered with filter fabric and capped with about 2 feet of the on-site soils to reduce surface water infiltration. 4) Roof downspouts and drains should discharge well beyond the limits of all backfill. 5) Landscaping which requires regular heavy inigation should be located at least 10 feet from foundation walls. PAVEMENT SECTION We understand asphalt pavement is proposed for the driveway. Traffic loadings for the driveway were not provided but are assumed to be relatively light with occasional truck traffic and typical of the type of development. We assume the pavement will be placed essentially after all construction truck traffic has been completed. The subgrade soils encountered at the site are generally low plasticity sand, silt and clay with gravel and scattered cobbles which are considered a fair support for pavement sections with a Hveem stabilometer 'R' value of 15. Imported fill will be needed for the roadway construction. The imported soil should be a sand and gravel material with a minimum Hveem stabilometer oR' value of 50. Based on our Kumar & Associatee, lnc. o Project No.2l-7-249 -8- experienoe, an l8 kip EDLA of 10, a Regional Factor of 2.0 and a serviceability index of 2.0, we recommend the minimum pavement section thickness consist of 3 inches of asphalt on 6 inches ofbasc coursc on 8 inches ofsubbase. The asphalt should be a batched hot mix, approved by the engineer and placed and compacted to the project specifications. The base course should meet CDOT Class 6 specifications. The subbase should meet CDOT Class 2 specifications. All base course and required subgrade fill should be compacted to at least95Yo of the maximum standard Proctor density at a moisture content within 2Yo of optimum. Required fill to establish design subgrade level can consist of the on-site soils or suitable imported granular soils approved by the geotechnical engineer. Prior to fill placement the subgrade should be scarified to a depth of 8 inches, adjusted to near optimum moisture and compacted to at least 95% of standard Proctor density. In soft or wet areas, the subgrade may require drying or stabilization prior to fill placement. A geogrid and/or subexcavation and replacement with aggregate base soils may be needed for the stabilization. The subgrade should be proofrolled. Areas that deflect excessively should be corrected before placing pavement materials. The subgrade improvements and placement and compaction of base and asphalt materials should be monitored on a regular basis by a representative of the geotechnical engineer. Once trafflrc loadings are beffer known, we should review our pavement section recommendations. LIMITATIONS This study has been conducted in accordance with generally accepte<l 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 borings drilled at the locations indicated on Figure 1, the proposed type of construction and our experience in the area. Our services do not include determining the presence, prevention or possibility of mold or other biological contaminants (MOBC) developing in thc futurc. If thc c.licnt is conccrned about MOBC, then a professional in this special field of practice should be consulted. Our findings include interpolation and extrapolation of the subsr¡rface conditions iclentifiecl at the exploratory borings and variations in the subsurface conditions may not becomc evident until excavation is perftrrmed. If conditiclns encclunterecl tluring uunstruution appear different lrom those ilescribed in this report, we should be notifred so that rc-evaluation of the recommendations may be made. Kumar & Associates, lnc. o Project No. 21-7-249 -9- This report has been prçared for the exclusive use by our client for design purposes. We a¡e not responsible for technical interpretations by others of our information. As the project evolves, we should provide continued consultation and field services during construction to review and monitor the implementation 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 recommend on-site observation of excavations and foundation bearing süata and testing of structural fill by a representative of the geotechnical engineer. Respectfully Submitted, Kumar & Associates, Inc. ,l Robert L. Duran, P.E. Reviewed by: Steven L. Paw RLDlkac cc:Compass LLC - Scott DeWind (scott@compasscm.co) IVA-J.R. Spung Kumar & Associates, lnc.'Þ Project No. 21.7'249 É LOT 52 40.748* ACRES *cú t"9 ¡'jl 3 Ël È \j-_ le -ilrfr.^æ¿/ ard¡idø \i\1. -1 I I t I I I I ( t BWLDTNçENWLOPT \ I I \ I,.,| ..\ \ ':jt') ì I ì I EsrlzrutI, SEøION 29 i sonlxc s ".r:;_ OBORTNG 2 N4ñ I f ,t+ -oro*,xo ., cæmÍcno[ 32 It.t.) L) i cEÊrsË iÁNct{ ÊOAD J I I IBORING 4 BORING 5 .: '. L."","'¡#..*,-Cfl-75.57' ! ,:i'l ./! ì 1 APPROXIMATE SCALE-FEET 21 -7 -249 Kumar & Associates LOCATION OF EXPLORATORY BORINGS Fig. 1 Fig. 2LOGS OF EXPLORAIORY BORINGSLOT 52 CERIST RANCHKumar & Associates21-7-249WC=5.6+4=22-2OO=47BORING 1EL. 6545'BORING 2EL- 6555'BORING JEL 6570'BORINGEL. 55'l47'BORING 5EL. 6,+87'BORING 6EL. 6,155'0IAfr:AY)ls"]VTK9?(5)W(1)(1)Bgffit(":Àvaffi012/1226/ 1249/121s/1211/12so/ 432/ tzWC=4.845/ 12WC=4.1+4=48-2OO=25LL=21Pl=3A-¡-b (o)tsIItsÈôso/5+4=39-200=36LL=25Pl=7a-4 (o)FIItsÈÕ072/12WC=2.910DD=103-200=7817 /1250/515so/62020MAIN RESIDENCE oo I 6 LEGEND ,.,m BASE COURSE, THICKNESS IN INCHES SHOWN IN PARENTHESES TO LEFT OF THE LOG. TOPSOIL; SILT AND CLAY, SANDY, FIRM, SLIGHTLY MOIST, TAN, ROOTS. CLAY AND S|LT (CL-ML); SANOV, ST|FF, SLTGHTLY MO|ST, TAN. BASALT GRAVEL, COBBLES, AND BOULDERS (GC-ML); IN A SANDY SILT MATRIX, MEDIUM DENSE TO DENSE, SLIGHTLY MOIST, TAN. l,-!',zl 6:¡Ålrrll BASALT COBBLES AND BOULDERS (GC); CLAYEY, SLIGHTLY SANDY, DENSE, SLIGHTLY MOIST, GRAY TO ÏAN. DRIVE SAMPLE, 2-INCH I.D. CALIFORNIA LINER SAMPLE i DRTVE SAMPLE, 1 3/8-rNCH t.D. SpLtT SPOON STANDARD pENETRATTON TESÏ. Áq/1, DRIVE SAMPLE BLOW COUNT. INDICATES THAT 49 BLOWS OF A 14O-POUND HAMMER.-,.- FALLING 30 INCHES WERE REQUIRED TO DRIVE THE SAMPLER 12 INCHES. I PRACTICAL AUGER REFUSAL. NOTES 1. THE EXPLORATORY BORINGS WERE DRILLED ON JUNE 17, ZO21 WITH A 4-INCH-DIAMETER CONTINUOUS-FLIGHT POWER AUGER. 2, THE EXPLORATORY BORINGS WERE LOCATED BY PACING. BORINGS 1 THROUGH 3 WERE LOCATED BY SCOTT DEWIND AND BORINGS 4 THROUGH 6 WERE LOCATED BY KUMAR & ASSOCIATES. 3. THE ELEVATIONS OF THE EXPLORATORY BORINGS WERE OBTAINED BY INTERPOLATION BETWEEN CONTOURS ON THE SITE PLAN PROVIDED. 4. ÏHE EXPLORATORY BORING LOCATIONS AND ELEVATIONS SHOULD BE CONSIDERED ACCURATE ONLY TO THE DEGREE IMPLIED BY THE METHOD USED. 5. THE LINES BETWEEN MATERIALS SHOWN ON THE EXPLORATORY BORING LOGS REPRESENT THE APPROXIMATE BOUNDARIES BETWEEN MATERIAL TYPES AND THE TRANSITIONS MAY BE GRADUAL. 6. GROUNDWATER WAS NOT ENCOUNTERED IN THE BORINGS AT THE TIME OF DRILLING. 7. LABORATORY TEST RESULTS: WC = WATER CONTENT (%) (ASTM D2216); DD = DRY DENSITY (pcf) (ASTM D2216);+4 = PERCENTAGE RETAINED ON NO. 4 SIEVE (ASTM 06913); -200= PERCENTAGE PASSING N0. 200 SIEVE (ASTM D1 1 a0);LL = LIQUID LIMIT (ASTM D4518);PI = PLASTICITY INDEX (ASTM D4518); A-4 (O) = AASHTO CLASSIFICATION (GROUP INDEX) (AASHTO M 145). 21 -7 -249 Kumar & Associates LEGEND AND NOTES Fig. 3 SAMPLE OF: Sondy Silt ond Cloy with Scoltered Grovel FROM:Boring2@9' WC = 2.9 %, DD = 103 pcf, -200 -- 78 % wlthoul th6 Ydtbñ opprovol of ADDITIONAL COMPRESSION UNDER CONSTANT PRESSURE DUE TO WETTING : :lii .: i: t, ; ) 1 : : I i: : I 2 0 à( -JJ LJ =Ø I zotr Õ =ovlz.oo -2 -4 -6 -8 1 0 -12 -14 -16 1.0 APPLIED PRESSURE - KSF 10 21 -7 -249 Kumar & Associates SWELL-CONSOLIDATION TEST RESULTS Fig. 4 E ¡ =f H too 90 ao 70 60 50 10 30 20 to o o to 20 50 40 50 60 70 ao 9o 100 3 H 38.1 DIAMETER OF IN MI CLAY TO SILT COBBLES GRAVEL 22 % SAND 51 % LIQUID LIMIT PLASTICITY INDEX SAMPLE OF: Very Cloyay Sllty Sond wlth Grovsl SILT AND CLAY 47 % FRoM: Borlng 1 O 8' & 15' (Comblned) 9 ø E too 90 80 70 60 50 ,to 30 20 to o to 20 50 40 50 60 70 ao e0 I too "129DIAMETER OF PARTICLES IN RS CLAY TO SILT COBBLES GRAVEL 39 % SAND LIQUIO LIMIT 25 SAMPLE 0F: Very Cloyêy Sondy Grovel 25x SILT ANO CLAY 3e% Th.!c l.!l r.3ultr qpply gnly lo lha somplos whlch w6r€ lqsl€d, lh!llsllng r.porl 3holl nol bc ruproducod, oxcopl ln full, rllhoul lho wrltl€nqpprqvql uf Kurrur t Asruulul€s, lñe.Sl.v. oñoly3h lcrllñg 13 prrfom.d ln occordonc. wllh.ASIM D69,l3, ASTM 07928, ASTM C136 ondlor ASTM Dll40. PLASTICITY INDEX 7 FROM:Borlng4@4' HYOROMETER ANALYSIS SIEVE ANALYSIS TIÍE RilDINO3 ¿4 HRS 7 HRS !CMIN u.3.3t ND^iD SEiES CLEAR gQUARE OPENINO3 atA. ./r. t 1/tr I I I I I I I t Ij I .l l I I I I I ! I I I I I I I I II rt t I I SAND GRAVEL FINE MEDIUM ICOARSE FIN E COARSE HYDROMETER ANALYSIS SIEVE ANALYSIS ÎIME RAOINGS 24 HRS 7 HnS lo floo U,S. STANOARD SERIES ¡30 ¡¡ô ¡30 ¡16 ¡ro ¡â CIEAR SQUARE OPEilINGS t/â' 3/L" 1 1/r' I i I I I T I I I i I I I II i I II tt I SAND ORAVEL FINE MEDIUM COARSE FINE COARSE 21 -7 -249 Kumar & Associates GRADATION TEST RESULTS Fig. 5 ! I ! EI I¡ E = f þ Ê roo 90 ao 70 ôo 50 10 50 20 lo o o lo 20 30 Æ 50 60 70 ao 90 100 I et -125 PARTICLES IN MILLI 2.O METERSDIAM CLAY TO SILT COEBLES GRAVEL 4A % SAND 27 % LIQUID LIMIT 21 PLASTICITY INDEX SAMPLE OF: Sllty Sondy Grovel SILT AND CLAY 25 % 3 FROM:Borlng6O,[' lh.!. l.!l rcaullr opp¡y only lo lh. sompl€s whlch v€ro losf.d. fho f.sllng r.porl sholl nol bo roproducod, excopl ln full, wllhout lho vrltt€n qpprovql ot Kumor & A¡sooiqlor, lnc. Sl.y. onolygtr la3llñg l! prrfom.d ln occordoncà wllh ASIM 06915, ASTM 07928, ASfM C136 qnd,/or ASTM Dll,l0. HYDROMETER ANALYSIS SIEVE ANALYSIS U.S. STANOARD SERIES CLEAR SQUARE OPENIXOS a/^.a'^.11/'. ltuE RAD|NCS 24 HRS 7 HnS lvtN I I i I /t. L Ili- l -- I ,-: . ,1 - ,, = ),,, :'t? I I I' I',t t r'ft SAND GRAVEL FINE MEDIUM ICOARSE FINE COARSE 21 -7 -249 Kumar & Associates GRADATION TEST RESULTS Fig. 6 rcÂiffii'ffiffi1t':iü*"'TABLE 1SUMMARY OF LABORATORY TEST RESULTSNo.2'l-7-249SOIL TYPEVery Clayey Silty Sandwith GravelSandy Silt and Clay withscattered GravelVery Clayey Sandy GravelSilty Sandy GravelAASHTO SOILCLASSIFICATIONA-4 (0)A-l-b (0)IololPLASTlCINDEX7aJATTERBERG L¡MIÏSf%rLIQUID UMTT25I2PERCENTPASSING NO.200 slEvE783625SAND('tù2527GRADATION(%)GRAVEL3948473l22103lololNAruRALMOISTURECONTENTNATURALDRYDENS]TY(pcfls.62.94.84.ttfttDEPTHI and 13Combined944SAMPLE LOCATIOIIBORII{GI246 I (trt ij|,ffififfifffini'liå*'" An Employoc Owncd Compony 5020 County Road 154 Glenwood Springs, CO 81601 phone: (970) 945-7988 fax: (970) 945-8454 email : kaglenwood@kumarusa.com www.kumarusa.com Ofñce Locations: Denver (HQ), Parke6 Colorado Springs, Fort Collins, Glenwood Springs, and Summit County, Colorado SUBSOIL STUDY FOR FOUNDATION DESIGN PROPOSED RESIDENCE AND ADU LOT 52, CERISE RANCH 360 CERISE RANCH ROAI) GARFIELD COUNTY, COLORADO PROJECT NO.2t-7-249 JULY 21,2021 PRE,PARED FOR: GLYNNA BAKER P.O. BOX s748 FRTSCO, COLORADO 80443-5748 qlvnna@ glvnnabaker.com TABLE OF CONTENTS PURPOSE AND SCOPE OF STUDY PROPOSED CONSTRUCTION SITE CONDITIONS.. FLOOR SLABS UNDERDRAIN SYSTEM.. SITE GRADING........... PAVEMENT SECTION LIMITATIONS FIGURE 1 - LOCATION OF EXPLORATORY BORINGS FIGURE 2 . LOGS OF EXPLORATORY BORINGS FIGURE 3 - LEGEND AND NOTES FIGURE 4 - SWELL-CONSOLIDATION TEST RESULTS FIGURES 5 and 6 - GRADATION TEST RESULTS TABLE I- SLTMMARY OF LABORATORY TEST RESULTS -1- 1 -1- FIELD EXPLORATION...-2- SUBSURFACE CONDITIONS J FOUNDATION BEARING CONDITIONS .....- 3 - DESIGN RECOMMENDATIONS............ ......- 4 - FOLINDATIONS ,.,.,..- 4 - FOLiNDATION AND RETAINING WALLS ................- 4 - SURFACE DRAINAGE ..............- 7 - _\_ .............- 6 - .............- 6 - .-8- _1_ Kumar & Assoclates, Inc. @ Project No. 21-7-249 PURPOSE AND SCOPE OF STUDY This report presents the results of a subsoil study for a proposed residence and ADU to be located atLot 52, Cerise Ranch, 360 Cerise Ranch Road, 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 supplemental to our agreement for geotechnical engineering services to Glynna Baker dated March 5,2021. We previously conducted a geotechnical review of the subject site for driveway and utilities and presented our findings in a report dated March 17,2021, Project No.2l-7-249. A field exploration program consisting of exploratory borings was conducted 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 analyzedto 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 main residence will be a two or three-story structure over a walk-out basement level with an attached garuge. The proposed ADU will be a one or two-story structure over a walk-out basement level. Ground floors will be slab-on-grade. Grading for the structures is assumed to be relatively minor with cut depths between about 5 to 10 feet. An asphalt paved driveway is proposed to access the proposed building sites from the southwest and along the existing rough graded road from Cerise Ranch Road. 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 subject site is currently vacant. There is a rough graded road that accesses the building area along the southem property line from Cerise Ranch Road and climbs up around to the north Kumar & A¡sociates, lnc. o Project No. 21-7-249 ., along the westem property line. Topography at the site consists of hillside terrain with slopes around I0 to 20 percent in the area of the proposed driveway, residence, and AD{J. Slopes of up to about 60 percent are present on the lot north ofthe building areas not planned for development. Vegetation at the site consists of native grass and weedso sage brush, juniper, and pinon. SUBSIDENCE POTENTIAL Bedrock of the Pennsylvanian age Eagle Valley Evaporite underlies the subject site. These rocks are a sequence of gypsiferous shale, fine-grained sandstone and siltstone with some massive beds of gypsum and limestone. There is a possibility that massive gypsum deposits associated with the Eagle Valley Evaporite underlie portions of the lot. Dissolution of the gypsum under certain conditions can cause sinkholes to develop and can produce areas oflocalized subsidence. During previous work in the area, several sinkholes were observed scattered throughout the Cerise Ranch development. These sinkholes appear similar to others associated with the Eagle Valley Evaporite in areas of the lower Roaring Fork River valley. Sinkholes were not observed in the immediate area of the subject lot. No evidence of cavities was encountered in the subsurface materials; however, the exploratory borings were relatively shallow, for foundation design only. Based on our present knowledge of the subsurface conditions at the site, it cannot be said for certain that sinkholes will not develop. The risk of future ground subsidence in the development area of Lot 52 throughout the service life of the proposed residence, in our opinion, is low; however, the owner should be made aware of the potential for sinkhole development. If further investigation of possible cavities in the bedrock below the site is desired, we should be contacted. FIELD EXPLORATION The fìeld exploration for the project was conducted on June 17, 2021. Six exploratory borings were drilled at the locations shown on Figure 1 to evaluate the subsurface conditions. The borings were advanced with 4 inch diameter continuous flight augers powered by a track- mounted CME 45 drill rig. The borings were logged by a representative of Kumar & Associates, Inc. Samples of the subsoils wcrc takcn with l% 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. 'llhis test is similar to the standard penetration test described by AS'I'M Method D-I586. The penetration resistance values are an indication of the relative density or consistency of the Kumar & Associates, lnc. o Project No, 21-7-249 -J- subsoils. Depths at which the samples were taken and the penetration resistance values are shown on the Logs of Exploratory Borings, Figure 2. The samples were returned to our laboratory for review by the project engineer and testing. SUBSURI.ACE CONDITIONS Graphic logs of the subsurface conditions encountered at the site are shown on Figure 2. In the area of the proposed main residence and ADU (Borings I -3), the subsoils consist of up to Yz feet of topsoil overlying up to 5 feet of sandy silty clay underlain by basalt boulders, cobbles, and gravel in a sandy silt matrix down to the maximum depth explored of 19 feet. Drilling in the coarse granular soils with auger equipment was difficult due to the cobbles and boulders and drilling refusal was encountered in the deposit at a depth of 18 feet in Boring 2 and 6Yz feet in Boring 3. In the area of the proposed driveway (Borings 4-6) the subsoils consist of 3 to 4 inches of road base overlaying slightly sandy clayey basalt gravel cobbles and boulders. In Boring 4, about 4% feet of sandy clay and silt was encountered between the road base and the clayey gravel. Laboratory testing performed on samples obtained from the borings included natural moisture content and density, Atterberg limits, and gradation analyses. Results of swell-consolidation testing performed on a sample of the sandy silt matrix material, presented on Figure 4, indicate moderate to high compressibility under conditions of loading and wetting. Results of gradation analyses performed on small diameter drive samples (minus l%-inch fraction) of the coarse granular subsoils are shown on Figures 5 and 6. The laboratory testing is summarizedin Table 1. No free water was encountered in the borings at the time of drilling and the subsoils were slightly moist. FOUNDATION BEARING CONDITIONS The subsoils encountered on the lot generally consist of basalt gravel cobbles and boulders in a sandy silt matrix. The upper silt and clay soils are low density and are typically known to be compressible when wetted under load. Lightly loaded spread footings can be used for support of the proposed residence provided that a risk of settlement and distress is acceptable to the owner. Removing the silt and clay soils and placing the footings on a depth (typically 2 to 3 feet) of compacted structural flrll could be used to reduce the risk of settlement. Kumar & Associates, lnc. @ Project No.21-7-249 -4- DESIGN RECOMMENDATIONS FOUNDATIONS Considering the subsurface conditions encountered in the exploratory borings and the nature of the proposed construction, we recommend the building be founded with spread footings bearing on the natural granular soils, beneath the upper fine-grained soils or compacted structural flrll placed on the natural granular soils. The design and construction criteria presented below should be observed for a spread footing foundation system. 1) Footings placed on the undisturbed natural granular soils or compacted structural hll should be designed for an allowable bearing pressure of 2,000 psf. Based on experience, we expect initial settlement of footings designed and constructed as discussed in this section will be about I inch or less. If the bearing soils were to become wetted, additional settlement up to around I inch could occur depending mainly on the depth and extent of wetting. 2) The footings should have a minimum width of 20 inches for continuous walls and 2 feet for isolated pads. 3) 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. 4) Continuous foundation walls should be heavily reinforced top and bottom to span local anomalies such as by assuming an unsupportcd lcngth of at least 14 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. 5) The topsoil, fine grained soils and any loose or disturbed soils should be removed and the footing bearing level extended down to the relatively dense natural granular soils. The exposed soils in footing area should then he moistenecl nnd compacted. 6) A representative ofthe geotechnical engineer should observe all footing cxcavations prior to concrete placement to evaluate bearing conditions. FOI-INDATION 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 Kumar & Associates, lnc. @ Project No. 2'l-7-249 5 computed on the basis of an equivalent fluid unit weight of at least 50 pcf for backfill consisting of the on-site soils. Cantilevered retaining structures which are separate from the residence or ADU 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 soils. Backfill should not contain organics or rock larger than 6 inches. All foundation and retaining structures should be designed for appropriate hydrostatic and surcharge pressures such as adjacent footings, traffic, construction materials and equipment. The pressures recommended above assume drained conditions behind the walls and a horizont¿l 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 90o/o of the maximum standard Proctor density at a moisture content near optimum. Backfill placed in pavement and walkway areas should be compacted to at least 95Yo of the maximum standard Proctor density. Care 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 backflrll should be expected, even if the material is placed correctly, and could result in distress to facilities constructed on the backfill. 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 0.40. Passive pressure of compacted backfill against the sides of the footings can be calculated using an equivalent fluid unit weight of 350 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 95o/o of the maximum 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 with a risk of settlement if the bearing soils are wetted. To reduce the effects of Kumar & Associates, lnc. @ Project No. 21-7-249 -6- some differential movement, 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 aggregate with at least 50%o retained on the No. 4 sieve and less than 2Yo passing the No. 200 sieve. All fill materials for support of floor slabs should be compacted to at least95Yo of maximum standard Proctor density at a moisture content near optimum. Required fill can consist of the on- site soils devoid of vegetation, topsoil and oversized rock. UNDERDRAIN SYSTEM Although free water was not encountered during our exploration, it has been our experience in the area 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 basement areas, be protected from wetting and hydrostatic pressure buildup by an underdrain system. The drains should consist of PVC 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 2Yo passing the No. 200 sieve, less than 50% passing the No. 4 sieve and have a maximum size of 2 inches. The drain gravel backfill should be at least IYzfeet deep and covered with filter fabric such as Mirafi l40N or 160N. An impervious membrane such as 20 or 30 mil PVC should be placed beneath the drain gravel in a trough shape and attached to the foundation wall with mastic to prevent wetting of the bearing soils. SITE GRADING The risk of construction-induced slope instability at the site appears low provided the buildings are located as planned and cut and fill depths are limitecl. We assume the cut depths for the basement levels will not exceed one level, about l0 to 12 feet. Fills should be limited to about 8 to 10 fcet dccp, cspccially at the downhill side of the resideuce or ADU where the slope steepens. Embankment hlls should be compacted to at least95o/o of the maximum standard Kumar & Associates, Inc. o Project No, 21-7-249 -7 - 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 95Yo 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 at2horizontal to 1 vertical or flatter and protected against erosion by revegetation or other means. This office should review site grading plans for the project prior to construction. SURFACE DRAINAGE The following drainage precautions should be observed during construction and maintained at all times after the residence and ADU have been completed: 1) 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 90% 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 3 inches in the first 10 feet in paved areas. Free-draining wall backfill should be covered with filter fabric and capped with about 2 feet of the on-site soils to reduce surface water infiltration. 4) Roof downspouts and drains should discharge well beyond the limits of all backfill. 5) Landscaping which requires regular heavy irrigation should be located at least 10 feet from foundation walls. PAVEMENT SECTION We understand asphalt pavement is proposed for the driveway. Trafflrc loadings for the driveway were not provided but are assumed to be relatively light with occasional truck traffic and typical of the type of development. We assume the pavement will be placed essentially after all construction truck traffic has been completed. The subgrade soils encountered at the site are generally low plasticity sand, silt and clay with gravel and scattered cobbles which are considered a fair support for pavement sections with a Hveem stabilometer 'R' value of 15. Imported fill will be needed for the roadway construction. The imported soil should be a sand and gravel material with a minimum Hveem stabilometer 'Ro value of 50. Based on our Kumar & Associates, lnc. o Project No. 21-7-249 -8- experience, an 18 kip EDL^ of 10, a Regional Factor of 2.0 and a serviceability index of 2.0, we recommend the minimum pavement section thickness consist of 3 inches of asphalt on 6 inches ofbase cùursc on 8 inches ofsubbase. The asphalt should be a batched hot mix, approved by the engineer and placed and compacted to the project speciflrcations. The base course should meet CDOT Class 6 specifications. The subbase should meet CDOT Class 2 speciflrcations. All base course and required subgrade fill should be compacted to at least95o/o of the maximum standard Proctor density at a moisture content within 2olo of optimum. Required fill to establish design subgrade level can consist of the on-site soils or suitable imported granular soils approved by the geotechnical engineer. Prior to fill placement the subgrade should be scarified to a depth of 8 inches, adjusted to near optimum moisture and compacted to at least 95% of standard Proctor density. In soft or wet areas, the subgrade may require drying or stabilization prior to flrll placement. A geogrid and/or subexcavation and replacement with aggregate base soils may be needed for the stabilization. The subgrade should be proofrolled. Areas that deflect excessively should be corrected before placing pavement materials. The subgrade improvements and placement and compaction of base and asphalt materials should be monitored on a regular basis by a representative of the geotechnical engineer. Once traffic loadings are better known, we should review our pavement section recommendations. LIMITATIONS This study has been conducted in accordance with generally accepted geotechnioal engineering principles and practices in this arca 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 borings drilled at the locations indicated on Figure l, the proposed type of construction and our experience in the area. Our services do not include determining the presence, prevention or possibility of mold or other biological contaminants (MOBC) developing in the ftrture. If the client is concerned about MOBC, then a professional in this special fîeld of practice should be consulted. Our findings include interpolation and extrapolation of the subsurface conditions identified at the exploratory borings and variations in the subsurface conditions may not become evident until excavation is perfcrrmed. If conditions encounterecl durilg uurutruu[iun appear differenl" from those desoribed in this report, we should be notified so that rc-cvaluation of the recommendations may bc made. Kumar& Aesociates, Inc. @ Project No. 21-7-249 -9- This report has been prepared for the exclusive use by our client for design purposes. Vy'e are not responsible for technical interpretations by others of our information. As the project evolvesn we should provide continued consultation and field services during construction to review and monitor the implementation 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 recommend on-site observation of excavations and foundation bearing sfata and testing of structural fill by a representative of the geotechnical engineer. Respectfully Submitted, Kumar & Associates, Inc. { Robert L. Duran, P.E. Reviewed by: Steven L. Paw RLDlkac cc: Compass LLC- ScottDeWind@) JVA-J.R. Spung Kumar & Associates, lnc. @ Project No. 21-7.249 LOT 52 +0,748t ACRTS -t", #tt2 / -1ud.^@É/ ñæreNMÐ\ú -1 -\\ 66É -_ 66¡, - 66f- I I I I ¡ I I ßI./Ú,LDÍNGEN:y{¿LoPI I #OBOR|NG 2 i{)ñfiR BORING 1 'l -o".oJ- . !!{grp2¡gta,;t'* -"a> 25.42'frsrtreæ', gcngv 2s I 6 It:}{:il í.l)i .'):i R.70.@' a?R.¡SE ßÁÀ,c# ROAD ì I BORING 4,::5 C8.S47 OA'OE\! ì 1 i ct 75.5?' !"ilT ,:t ì lUU U lUU 2UU APPROXIMATE SCALE-FEET 21 -7-249 Kumar & Associates LOCATION OF EXPLORATORY BORINGS Fig. 1 WC=5.6+4=22-2OO=47BORING 1EL- 6545'SORING 2EL. 6555'EORING 3EL. 6570'BORING ¡tEL. 55t7'BORING 5EL. 6487'BOR¡NG 6EL. 6¡155'ol-zf i/'Y)VTHÐ?(5)(1)(1)mWþAlrÞ{ffio_]lll. --l-l_.1tt:''_"o-12/1226/1213/124s/12so/ 411/1232/ t2WC=4.84s/ 12WC=4.1+4=48-2AO=25LL=21Pl=3A-1-b (0)5so/s+4=39-200=36LL=25Pt=7A-4 (o)tsI-Fùô1072/ 12WC=2.9DD= I 03-2OO=7A17 /1250/5so/620MAIN RESIDENCEADUDRIVEWAYFig. 2LOGS OF TXPLORATORY BORINGSLOÏ 52 CERISE RANCHKumar & Assoc¡ates21-7-249 LEGEND (4)BASE COURSE, THICKNESS IN INCHES SHOWN IN PARENTHESES TO LEFT OF THE LOG. TOPSOIL; SILT AND CLAY, SANDY, FIRM, SLIGHTLY MOIST, TAN, ROOTS. CLAY AND SILT (CL-ML); SANDY, STIFF, SLIGHTLY MOIST, TAN BASALT GRAVEL, COBBLES, AND BOULDERS (GC-ML); IN A SANDY SILT MATRIX, MEDIUM DENSE TO DENSE, SLIGHTLY MOIST, TAN. BASALT COBBLES AND BOULDERS (GC); CLAYEY, SLIGHTLY SANDY, DENSE, SLIGHTLY MOIST, GRAY TO TAN. DRIVE SAMPLE, 2-INCH I.D. CALIFORNIA LINER SAMPLE. DR|VE SAMPLE, 1 3/8-tNCH t.D. SpLtT SPOON STANDARD PENETRATTON TEST. aq/,t? DRIVE SAMPLE BLOW COUNT. INDICATES THAT 49 BLOWS OF A 14O-POUND HAMMER.-,.- FALLING 30 INCHES WERE REQUIRED TO DRIVE THE SAMPLER 12 INCHES. PRACTICAL AUGER REFUSAL. NOTES THE EXPLORATORY BORINGS WERE DRILLED ON JUNE 17,2021 WITH A 4_INCH-DIAMETER CONTINUOUS-FLIGHÏ POWER AUGER. 2. THE EXPLORATORY BORINGS WERE LOCATED BY PACING. BORINGS 1 THROUGH 5 WERE LOCATED BY SCOTT DEWIND AND BORINGS 4 THROUGH 6 WERE LOCATED BY KUMAR & ASSOCIATES. 3. THE ELEVATIONS OF THE EXPLORATORY BORINGS WERE OBTAINED BY INTERPOLATION BETWEEN CONTOURS ON THE SITE PLAN PROVIDED. 4. THE EXPLORATORY BORING LOCATIONS AND ELEVATIONS SHOULD BE CONSIDERED ACCURATE ONLY TO THE DEGREE IMPLIED BY THE METHOD USED. 5. THE LINES BETWEEN MATERIALS SHOWN ON THE EXPLORATORY BORING LOGS REPRESENT THE APPROXIMATE BOUNDARIES BETWEEN MATERIAL TYPES AND THE TRANSITIONS MAY BE GRADUAL. 6. GROUNDWATER WAS NOT ENCOUNTERED IN THE BORINGS AT THE TIME OF DRILLING. 7. LABORATORY TEST RESULTS: WC = WATER CONÍENT (%) (ASTM D2216); DD = DRY DENSITY (pcf) (ASTM D2216);+4 = PERCENTAGE RETAINED ON NO. 4 SIEVE (ISTV OOSIS); _2OO= PERCENTAGE PASSING NO. 2OO SIEVE (ASTM D11AO);LL = LIQUID LIMIT (ASTM D4318);PI = PLASTICITY INDEX (ASTM D4318); A-4 (O) = AASHTO CLASSIFICATION (GROUP INDEX) (AASHTO M 145). I I 21 -7 -249 Kumar & Associates LEGEND AND NOTES Fig. 36 E I I SAMPLE OF: Sondy Silt ond Cloy with Scollered Grovel FROM:Boring2@9' WC = 2.9 %, DD = 103 pcf, -200 = 78 % ADDITIONAL COMPRESSION UNDER CONSTANT PRESSURE DUE TO WETTING : :i: l In opp¡ovol ol 2 0 às JJ L¡l =Ø I zotr ê =o Lt1zoo -2 -4 -6 -8 1 0 -12 -14 -16 f.0 PRESSURE _ KSF 10 f00 Fig. 4SWELL-CONSOLIDATION TEST RESULTS21 -7 -249 Kumar & Associates too g0 ao 70 €o 50 40 30 l0 o 10 20 30 40 50 60 70 60 90 100 ? P Ë 200 DIAMETER OF 2.OIN MILLIMEÏERS CLAY TO SILT COBBLES GRAVEL 22 % SANO 51 % LIQUID LIMIT PLASTICITY INDEX SAMPLE OF: Very Cloyåy Sllty Sond wlth Groval SILT AND CLAY 47 % FRoM: Borlng 1 O 8' & 15' (Comblned) I too 90 80 70 60 50 ¡o 50 20 t0 o o to 20 50 ,40 50 80 70 80 90 r00 = 1,ta.125 DIAMETER OF IN MI S CLAY TO SILT COBBLES GRAVEL 39 % SAND LIQUID LIMIT 25 SAMPLE OF: V€ry Cloyey Sondy crovel 25% PLASTIEIÏY INDEX SILT AND CLAY 36 % 7 FROM:Borlng4@4 Thr!. l.st rô!ulls qpply only lu llra sqmplog rhlch war€ lgslcd. Thr lcsllng reporl sholl not bc r.producod, GxcrÞl ln full. wllhôr¡l lhi wrltl.D opprcvql of Kumor & Assoclotos, lnq.Sl.v. qñolysls l.3llng lr parfomld ln occordonco wllh AS'rM D6913, ASÍM 07928, ASTM C156 ondlor ASTM Dll,l0. HYOROMETER ANALYSIS SIEVE ANALYSIS ltME RE^O|ilCt 24 HRS 7 HRSa5 ltN t¡ ut{ aÔvl{ taltN u.a. aT flDARO SsftEa ogn aou^nE onrr¡r¡roE I "/ I ¡ I i I I I I I'ì I I I I I lttt I SAND GRAVEL FINE MEDIUM COARSE FINE COARSE HYDROMEÎER ANALYSIS SIEVE ÀNÀLYSIS 24 HRS 7 HRS6 MtN 15 ÍtN tutñ lIME READINGS aovtN teftN 4vrN U,S, STANOARD SERISS CLSR SOUARE OPENINCS 3/A" t/1" 1 1/r' /lr l. -t I Ir t,-l I Irli¡l I i I I I I .I I SAND GRAVEL FINE MEDTUM lcoanse FINE COARSE 21 -7 -249 Kumar & Associates GRADATION TIST RESULTS Fig. 5 ¡I I 3 I I ø ã 100 90 a0 70 6o 50 ß 30 20 10 o o lo 20 50 10 50 50 70 a0 90 ioo I 2t DIAMETER OF IN MILLIMETERS CLAY TO SILT COBBLES GRAVEL 18 % SAND 27 % LIQUID LIMIT 21 PLASTICITY INDEX SAMPLE OF: Sllty Sondy Grovål SILT AND CLAY 25 % 3 FROM:Borlng6O4' lh.s. lcll rusulls qpply only lo lhr sompl.s vhlch vors l.sl6d. fhr lc¡llng roÞorl shqll nol b! r.producsd, sxcopl ln full, wllhoul lho wrltton opprcvol of Kumqr & A!¡gclql.s, lnc. Sicvc onolyrls laltlng h parlom.d ln occordqncå wilh ASTM 06915, ASIM 07928, ASTM c156 ond/or AsfM 0tl,l0. SIEVE ANALYSISHYDROMEfER ANALYSIS u.s. sl NDARo sERtEs CMR SQUARE OPÊXINOS atA- rr^r I 1/ta frxE REAoI{ôS ¿4 HRS 7 HRS t I ,1., ,i. I I-l SAND GRAVEL FINE MEOIUM ICOARSE FINE COARSE 21 -7 -249 Kumar & Associates GRADATION TEST RESULTS Fig. 6 € I rcrf $ffififfifffii'"nË;n'**TABLE ISUMMARY OF LABORATORY TEST RESULTSNo.2l-7-249Sandy Silt and Clay withscattered GravelVery Clayey Sandy GravelSilty Sandy GravelSOIL TYPELIQUID LIMTTAVery Clayey Silty Sandwith GravelAASHTO SOILCLASSIFICATIONPLASTICINDEXA-4 (0)A-l-b (0)7aJ25I2PERCENTPASS|T{G NO.200 stEvE47783625lf/,|SANDIJ2527GRADATIONlv,lGRAVEL223948DEPTHSAMPLEBORINGNATURALDRYDENSTTYNATURALI4OISTURECONTENT1035.62.94.8I48 and 13Combined944I246