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Home My WebLink AboutGeotechnical StudyHEPWÕRTT{ - PAWLAK GËOTËCHN IÇAL l-lrl,rr,,l t I l - l'¡\\ lilL: ( ii'¡'¡ r¡:l rllllill. I ¡rr{flli t',,¡r¡rr 11',;¡,1 I 5-f t- iLltiitr,',¡l l¡'¡¡¡¡-.,. (, rlrri';rLj, ¡ rlr¡ill i:\l rr rrrq:: it'li.r"r.¡-¡5 " ;r;¡¡ F:rr:,li¡t-r.¡,¡5-nn t.t (:11 ¡il I I : h ltlr'r iji{.rlllr!{] rrr Ih,¡., ¡r}ì H PRtrLIMINARY GEOTECHNICAL STUDY PROPOSED TCI LANE RANCH SUBDIYTSION HIGHWAY 82 AND EAST OF COUNTY ROAD lOO GARFIELD COUNTY, COLORADO JOB NO. 106 0920 MARCH 14,2008 PREPARED FOR: TCI LANE RAI\¡CH, LLC C/O NOBLE DESIGN STUDIO ATTN: JON FREDERICKS, ASLA 19351 HIGHWAY 82 CARBONDALE, COLORADO 81623 t.l,rllrrlçl,i 5l.rrng. '7 1')-6ìì-iifrl r frlli,¡111r()ll¡r' ');'{.-ì -+í'}¡i. lt¡;-i!ll.ir¡'L:i r' 1ül-,\,+l -7 I li)I TABLE OF CONTENTS PURPOSE AND SCOPE OF STUDY SITE CONDITIONS.. REGIONAL GEOLOGIC SETTING..... PROJECT SITE GEOLOGY RTVER TERRACES AND DEPOSITS. EAGLE VALLEY EVAPORITE GEOLOGIC SITE ASSESSMENT.............. RIVER FLOODING SINKHOLES ............... EARTHQUAT(E CONSrDERATrONS.................. RADIATIÛN POTENTIAL......,. FIELD EXPLORATION SUBSURFACE CONDITIONS PRELIMINARY DESIGN RECOMMENDATIONS FOLINDATIONS BELOW GRADE CONSTRUCTION,...... FLOOR SLABS SURFACE DRAINAGE ................... PAVEMENT SECTION .............. LIMITATTONS ................ REFERENCES ................. FIGURE 1 _ PROJECT SITE LOCATION FIGURE 2 _ GEOLOGICALLY YOTING FAULTS AND LARGER HISTORIC EARTHQUAI(ES FIGURE 3 _ WESTERN COLORADO EVAPORITE RECION FICURE 4 _ PROJECT AREA GEOLOGY MAP FIGURE 5 _ LOCATION OF EXPLORATORY PITS FIGURE ó _ LOGS OF EXFLORATORY PITS FIGURE 7 . LEGEND AND NOTES FIGURE 8 . SWELL-CONSOLIDATION TEST RESULTS FIGURES 9, 10, 11 8L 12 - CRADATION TEST RESULTS TABLE I. SUMMARY OF LABORATORY TEST RESULTS PURPOSE AND SCOPE OF STUDY This report presents the results of a prelirninary geotechnical study for the proposed residential subdivision at TCI Lane Ranch located no*h of the Roaring Fork River and east of the Blue Cteek Ranch subdivision, Garf,eld County, Colorado. The project site is shown on Figure L The purpose of the study was to evaluate the geologic and subsurface conditions and their potential impact on the project. The study was conducted in accordance with our proposal for geotechnical engineering services to TCi Lane Ranch, LLC, dated December 20,2A07. We previously conducted percolation testing for a septic system design on the prcperty and presented our findings in a report dated October 31, 2006, Job No. 106 0920. A field exploration program consisting of a recoruraissance and exploratory pits was conducted to obtain inforrnation on the site and subsurface conditions. Samples ofthe 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 project plannìng and preliminary design. This report summarizes the data obtained cluring this study and presents our conclusions and recommendations based on the proposed development and subsurface conditions encountered. SITE CONDITIONS The TCI Lane Ranch covers about 100 acres ancl is located in the Roaring Fork River valley about three ancl one-half rniles upstream of Carbondale, see Figure 1. The property lies to the north of the river and is entirely on the nearly level valley floor, The valley floor has ân average slope of about 2 pelcent down to the west. It is rnade up of several river terrace levels that are separated by low escatpments. The escarpments are typically about 6to 20 feet high and have slopes of about 50 to 70 percent. The tenace surfaces lie between about 4 to 46 feet above the river. The Frontage Road for Higltway 82 is located along the lrorthem property line. Parts of the southem property line are in Job No. 106 0920 eåFtecrr -/- the Roaring Fork River channel. The Blue Creek Subclivision borders the properly on the west and rural homes and agricultural land are locatecl on the prirpelties to the east. At the time of this study several houses and ranch buildings were located in the east-central part of the TCI Lane Ranch. Much of the ranch is inigated hay fields and pasture which are locatecl rnostly on the higher terace surfaces. Cottonwood trees, other trees and brush are typical of the vegetation on the lower teraces. Pooriy drained wetlands are also present on the lower ten'aces. PROPOSED DEVELOPMENT The proposed developurent at the TCI Lane Ranch rvill be mostly a residential subdivision as shown on Figure 4. A plant nursery will be located in the northwestem part of the properly. The lowest tenaces along the river will not be developed and undeveloped ground will remain along Highway 82. Eighty-nine residential lots are proposed. Other developrnent facilities will include a network of streets, a community park and other community facilities. If developrnent plans change significantly fi'orn those clesuibed, we should be notified to re-evaluate the recommendations presented in this repoft. REGIONAL GEOLOGIC SETTING The project site is in the Southern Rocky Mountains to the west of the Rio Grande rift ancl to the east of the Colorado Plateau, see Figure 2. The site is in the westem Colorado evaporite region and is in the Carbondale collapse center, see Figure 3. The Carbondale collapse center is the western of two regional evaporite collapse centers in westem Colorado. It is an irregular-shaped, northwest trending region between the White River uplift and Piceance basin. It covers about 460 square miles. As much as 4,000 feet of regional subsidence is believed to have occuttecl during the past 10 million years in the vicinity of Carbondale as a result of dissolution and flowage of evaporite fiom beneath the regions (Ifirkham and Others, 2002). The evaporite is mostly in the Eagle Valley Evaporite with some in the Eagle Valley Fonnation. The Eagle Valley Evaporite is tlie near surfàce formation rnck below the surficial soil deposits at the project site, It crops .lolr No. 106 0920 c,äFteclr -3- out or the steep valley side to the south of the river, see Figure 4. Much of the evaporite relatecl subsidence in the Carbondale collapse center appeal's to have occured within the past 3 million years which also conesponrls to high incision rates along the Roaring Fork, Colorado and Eagle Rivers (Kunk and Others, 20AÐ. This indicates that long-term subsidence rates have been vety slow, between about 0.5 and 1.6 inches per 100 years. It is uncertain ifregional evaporite subsidence is still occuning or if it is currently inactive. If stiil active these regional deformations because of their very slow rates should not have a significant impact on the propose development at the TCI Lane Ranch. Geologically young faults related to evaporite tectonics are present in the Carbondale collapse center but considering the nature of evaporite tectonics, these fault are not considered capable of generating large earthquakes. The closest geologically youtlg faults that are less than about 15,000 years old and considered capable ofgenerating large earthquakes are located in the Rio Grande rilt to the east of the project site, see Figute 2. The northem section of the Williarns Fork Mountains fault zone Q50 is located about 60 miles to the northeast and the southern section of the Sawatch fàult zone Q56b is located about 60 tniles to the southeast, At these distances large earthquakes on these two geologically young fbult zones should not produce strong ground shaking at the project site that is greater than the ground shaking shown on the U. S. Geological Survey 2002 National Seisrnic Flazards Maps (Frarikel ancl Others, 2002} PROJECT SITE GEOLOGY The geology in the project area is shown on F'igure 4. This map is based on our fìeld obsetr¡ations and is a rnodiflrcation of the legional geology nrap by Kirkharn and Widmann (1997). Near surface formation rock is the rniddle Pennsylvanian-ageo Eagle Valley Evaporite. This regional rock formation was deposited in the central Cololado trough during the Ancestral Rocky Mouutain orogeny about 300 million years ago. At the pmject site the evaporite is covered by a sedes of Roaring Fork River terraces and cleposits that are associated with cyclic periocls of cleposition and erosion related to glacial zurd interglacial climatic fluctuations cluring about the past 35 thousancl )iears. .lob No. l0ó 0920 cåFtecr' -4- RIVER TERRACES AND DEPOSITS Remnants of seven river terace levels (Qtl tluough QtT) are present at the project site. The lower four tenaces are probably related to post*Pinedale clirnatic fluctuations during the past 15 thousand years. Tenace Qtl lies within 4 feet of the river. Tenace Qt2 lies about 6 feet above the river, tenace Qt3 lies about 12 feet above the river and ten'ace Qt4 is about 22 feet above the river. The Qtl terraces are small river bank terraces and channel bar deposits. The Qt2 terraces a¡e old abandonecl river channels that lie bolow the Qt3 teüace surface. The thlee higher terraces are probably associated with the late Pleistocene-age, Pinedale glaciations between about l5 and 35 thousand years ago. Terrace Qt5 lies about 38 feet above the river, temace Qt6 lies about 40 feet above the river and terace Qt 7 lies about 46 feet above the river. Our exploratory pits show that the alluvial deposits below tefface levels Qt3 tluough Qt7 are sirnilar. They consist of a thin, less than 1-foot thick to 3-foot thick, topsoil formed in soft, silty clay over-bank deposits. The over-bank cleposits overlie river alluvium that consists of rounded gravel- to boulder-size rocks in a relatively clean sand matrix. The river alluvium extended to the bottom of the exploratory pits that were excavated to depths of arouncl 9 feet. Judging fiom water well records in the Colorado State Engineer's data base the river alluvium is probably in the range of 40 to 50 feet cleep in the prdect area. EAGLE VALLEY EVAPORITE The Eagle Valley Evaporite underlies the Roaring Fork Rivel alluviurn in the project area and as discussed above may extend to depths of 40 to 50 feet below the tenace surfaces. Tlie Eagle Valley Evaporite is a sequence of evaporite rocks consisting of massive to laminated gypsum, anhydrite, and halite ilrtelbedded with liglrt-colored mudstone, fine- grained sandstone, thin limestone and dolomite beds and black shale (Kirkharn and Widmann, 1997). The evaporite minerals are relatively soluble in circulating ground water and subsurface solution voids and related surface sinkholes are locally present in these rocks throughout the western Colorado evaporite region where the evaporite is near Job No. 106 0920 cåEtecrr -5- the surface, see Figure 3. Sinkholes were not obserued at the project site during our field work but the snow cover at that tirne may have obscured sinkholes if present. GEOLOGIC SITE ASSESSMENT Geologic conditions that could present an unusually high risk to the praposed development were not identified by this study but there are geologic conditions that should be considered in the project planning and design. These conditions, their potential risks and possible uritigations to reduce the risks are discussed below. Geotechnical engineering design considerations ¿u'e presented in the Preliminaly Design Recommendations section of this report. RIVER FLOODING The low lying tenaces along the Roaring Fork River may be subject to periodic flooding during high river flows. The hydrologic study conducted for the project stor"m water management plan design should evaluate the potential for river flooding and possible metliods to protect project facilities from au apprnpriate design flood on the river. SINKI-IOLES Geologically young sinkholes are present in the western Colorado evaporite region mostly in areas where the Eagle Valley Fonnation and Eagle Valley Evaporite are shallow, see Figure 3. In this region a few sinkholes have collapsed at the ground surface with little or no warning during historic times. This indicates that infrequent sinkhole fonnation is still an active geologic process fur the region. Evideirce of sinkholes was not observed at the project site during our fielcl reconnaissance or aerial photogtaphs review but could have been obscured by the snow oover. A field review to look for sinkholes in the prnpr:sed building area should be made after the site is clear of snow cover. Although geologically active in the region , the likelihoocl that a sinkhole will developtnent cluring a reasonable exposure tirne at the project area is considered to be low. This inference is JoLr No. l0ó 0920 cåBteclr -6- based on the large extent of sinkhole prone areas i¡r the region in comparison to the srnall number of sinkholes that have developed in historic times. Because of the complex nature of the evaporite related sinkholes, it will not be possible to avoid all sinkhole risk at the project site. If conditions indicative of sinkhole rclated problems are encountered during site specific soil and foundation studies for the houses and other rnovernent sensitive faculties, an alternative building site should be considered or thç feasibility of mitigation evaluated. Mitigation measures coulcl include: (l) a rigid mat foundation, (2) stabilization by grouting, (3) stabilizationby excavation and backfilling, (4) a deep foundation system or (5) structural bridging. Water features should not be considered close to building sites, unless evaluated on a site specific basis. The home owners could purchase special insurance to reduce their potential risks. Ptospective owners should be advised of the sinkhole potential, since early detection of building distress and tirnely remedial actions are impoftant in reducing the cost of building repair should an undetected subsurface void staû to develop into a sinkhole after constructiorr. EARTHQUAI(E CONSIDERATIONS Historic earthquakes within 150 miles of the project site have typically been moderately strong with magnitudes of M 5.5 and less ancl maximurn Modified Mercalli Intensities of VI and less, see Figure 2. The largest historic earthquake in the project region occu'red in 1882, It was located in the nofihem Front Range about I l5 miles to the northeast of the project site and had a estirnated niagnitude of aboutlli{ 6.2 and a maximun'r intensity of VIL Historic ground shaking at tlie project site associated with the 1882 ancl the other larger historic earthquakes in the region does not appsar to have exceeded Modified Mercalli Intensity VI (ifirkharn and Rogers, 1985). Modified Mercalli Intensity VI ground shaking should be expected during a reasonable exposure time for the houses and other project facilities , but the ptobability of stronger ground shaking is low. [ntensity VI ground shaking is felt by most people and causes general alarm, but results in negligible damage to structures of good design and construction, Job No. 106 0920 cåFtecrr .| The houses and other facilities subject to earthquake damage should be designed to withstand moderately stroug ground shaking with little or no damage ancl not to collapse under stronger ground shaking. Forfirm roclc sítes with shear wave velocities of 2,500 fps in the upper 100 feet, the U. S. Geological Survey 2002 Natíonal Seismic Hazard Maps indicate that a peak ground acceleration of 0.069 has a 10o/o exceedence probability for a 50 yeal exposure time and a peak ground acceleration o{A.23ghas aZYo exceedence probability for a 50 yeår exposure time at the project site (Frankel and Others, 20tZ). This corresponds to a statistical recurence time of about 500 years and 2,500 years, respectively. The soil profiles at the building sites should be considered as Class C,firm roclc sites as described in the 2006 International Building Code unless site specific shear wave velocity studies show otherwise. RADIATION POTENTIAL Regional studies by the Colorado Geological Suvey indicate that the closest radioactive mineral occuffences to the project site ale greater that twenty milos fionr thc site (Nelson-Moore and Others, 1978). Radioactive mineral occuffences are present in the Aspen-Lenado mining clistrict to the southeast and on the southwest flank of the White River uplift to the nofthwest. Regional studies by the U. S, Geological survey (Dubiel, 1993) for the U. S. Envirorunental Protection Agency (EPA) indicate that the ploject site is in a moderate raclon gas potential zone. The 1993 EPA regional radon study considered data flom (i) indoor radon surveys, (2) aerial radioactivity surveys, (3) the general geology, (4) soil permeability estimates, and (5) regional architectural practices. It is not possible to accurately assess future radon concentrations in buildings before they are consttucted. Accurate tests of radon concentrations can only be made when the buildings have been completed. Because of this, new buildings in modelate to high radon areas are often designed witli provisions for ventilatíon of the lower enclosed areas should post construction testing show unacceptable radon concentrations, iob No. 106 0920 eåStecn -8- FIELD EXPLOR,A.TION The field exploration fbr the project was conducted on January 10 and 15, 2008. Twelve exploratory pits were excavated at the locations shown on Figure 5 to evaluate the subsurface conditions. The pits were dug with a trackhoe and were logged by a representative of Hepworlh-Pawlak Geotechnical, Inc. Sanrples of the subsoils were taken with relatively undisturbed and disturbed sarnpling rnethods. Depths at which the samples were taken are shown on the Logs of Exploratory Pits, Figure 6. The sarnples 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 6. The subsoils consist of about Yz ta 3 feet of organic topsoil overlying 2 feet of silty sand in Pit I and relatively dense, silty sandy gravel containing cobbles and boulders in the remainirrg pits. Pit 3 contained a lens of slightly gravelly sand from 4 ta syz feet. Laboratory testing perfonned on sarnples obtained ûom the pits included natural moisture content and density and gradation aualyses. Results of swell-consolidation testing performed on a relatively undisturbed sample, presented on Figure 8, indicate moderate compressibility under co¡rditions of loading and wetting. Results of gradation analyses performed on large disturbed samples (rninus 3 to 5 itich ilaction) of the natural coarse granular soils are shown on Figures 9 through 12. The laboratory testing is summarized in Table I. No free water was encountered fur the pits at the time of excavation and the subsoils were slightly rnoist. PRELIMINARY DESIGN RECOMMtrNDATIONS The conclusiorts and recommendations presented below are based otr the proposed clevelopment, sutrsurface conditions encountered in the exploratory pit, and our experience fur the area. The recommendations are suitable for planning and preliminary desigrr but site specific studies should be conducted for individual lot development. Jr:h No. 106 0920 c&Btecrr -9- FOUNDATIONS Bearing conditions will vary clepending on the specific location of the builcting on the property. Based on the nature of the proposed construction, spread footings bearing on the natural granulat soils should be suitable at the building sites. We expect the footings can be sized for an allowable bearing pressure in the range of 1,500 psf to 3,000 psf. Compressible silty sands encountered in building areas rnay need to be removed or the footings designed accordingly as pâlt of the site specific lot stuily. Nested boulders and loose matdx soils may need treatment such as enlarging footings or placing compacted stiuctural fill. Foundation walls should be designed to span local anomalies and to resist lateral earth loadings when acting as retaining sttuctures. The footings should have a minimum depth of 36 inches for frost plrtection. BELOW GRADE CONSTRUCTION Free water was encountered in some of the exploratory pits and it has been our experience in the area that the water level can rise and local perched groundwater can develop during tirres of seasonal runoff ancl heavy irrigation. In general, all below grade areas should be protected from wetting and hydrostatic pressure buildup by use of an underdrain system. We reconrmend that slab-on-grade floors be placed near to above existing grade and crawlspaces be kept shallow. Basement levels may not be feasible in the lower lying areas with a shallow groundwater level. Potential groundwater impacts on proposed development should be evaluated as part of the site specific building study. FLOOR SLABS Slab-on-grade construction should be feasible for bearing on the natural granular soils below the topsoil. There could be some post construction slab settlernent at sites with cornpressible silts and sands. To reduce the effects of some differential rnovernent, floor slabs should be separated from all bearing walls and columrs with expansion joints, Floor slab control joints should be used to reduce damage due to shrinkage cracking. A Job No. 106 092û cåBtecrr - t0- minimum 4 inch thick layer of free-draining gravel should underlie building slabs to break capillary water dse aud facilitate drainage. SURFACE DRAINAGE The grading plan for the subdivision should consider runoffthrnugh the project and at individual sites, Water should not be allowed to pond next to buildings. To limit infiltration into the bearing soils next to buildings, exterior backfill should be well compacted and have a positive slope away fiom the building for a distance of at least l0 feet. Roofdownspouts and drains should discharge well beyond the limits of all backfill and landscape irrigation should be restricted. PAVEMENT SECTION The near surface soils encountered in the exploratory pits below the topsoil tlpically consisted of silty sandy gravel. The pavernent section fbr the site access roads can be taken as 3 inches of asphalt pavement on I inches of Class 6 aggregate base course for preliminary design purposes. The subgrade should be evaluated fbr pavement support at the time of constn¡ction. Subexcavation of the topsoil and fine-grained soils and replacement with coarse granular subbase material may be needed to achieve a stable subgrade in some areas. LIMITATIONS This stucly has been conducted according to gener:ally accepted geotechnical engineering principles and practices in this area at this tirne. We make no wananty eíther express or irnplied. The conclusions and recommendations subrnitted in this report are based upon the data obtained fi'om the field recormaissance, review of published geologic repofts, the exploratory pits located as shown on Figure 5 and to the clepths shown on Figure 6, the proposecl type of constnrction and our experience in the area. Our consulting services do not include cletennining the presence, prevention or possibility of nrold or other biological contaminants (MOBC) developing in the future. If the client is concernecl about MOBC, then a ¡:rofessional in this special field of practice should be consulted. Our fìndings Job No. 106 0920 e&Ftecn - 11- include interpolation and extrapolation ofthe subsurface conditions identified and the exploratory pits and variations in the subsurface conditions may not become evident until excavation is perfonned, If conditions encountered during construction appear different from those desoribed in this report, we should be notified so that re-evaluation of the recommendations rnay be made. This report has been prepared for the exclusive use by our client for planning and plelirninary desígn puryoses. We are not responsible for technical interpretations by others of our information. As the project evolves, we should provide continued consultation, conduct additional evaluations and review and monitor the irnplementation of our recommendations. Significant design changes may require additional analysis or modifications to the recornmendations presented herein. We recommend on-site obselation of excavations and foundation bearing strata and testing of structural fill by a representative o f the geotechnical engineer. Respectfirlly Submitted, HEPWORTH - PAWLAK GEOTECHNICAL, INC, Scott Vl. Richards, E.I. Reviewed by: Steven L. Pawlak, P.E SWR/vad Job No. 106 0920 c$teclr -12- REFERENCES Dubiel, R. F., 1993, Prelimínary Geologtc Rødon Potential Assessment of Colorado in Geologic Radon Potential EPA Region 8, Cr¡lorado, Montana, North Dakota, South Dakota, Utah anrl Wyoming: U. S. Geological Survey Open File Report 93- 292-H. Frankel, A. D. and others, 2002, Docuntentationþr the 2002 Update oJ'the Natianal Seismic Hazard Maps; U. S. Geological Survey Open File Report A2-420. Kirkhanr, R. M. and Rogers, W. P., 1985, Colorado Earthquake Data and Interpretations 1867 to 1985: Colorado Geological Survey Bulletin 46. Kìrklrar4 R. M. and widmann, B. L., 1997, Geologt Map of the Carbanrlale Quadrangle, Ga(ield County, Colorado: Colorado Geological Survey Open File 97-3. Kirkham, R. M. and Scott, R. 8., 2AA2,Introduction to Late Cenozoic Evaporite Tectonism ønd Volcanism in West-Central, Colorado, in Kirkham R. M., Scott, R. .Iolr No, 106 092t cåFtec+r !"*':t_l ,i'r'åd,* ¡¡{ -.*l";,...' ".-:_\ i.:4\:'ro'1,,'t- .,..Ê¡l I¡.:$dt, ri¡1tIii"{ç:"t; ''¡,.)lI *ot:\VJi ).: ,j'tl '-_\'lf Qf = lerueful rnofuo$'[ 0000 ¡ 'q t iepcg0000e0¿60 90tlvCiltlp¡Iolo )tï$vd-H¡,uon{rHqcatgfrÐuol}eco-lâlls pa[oJdlcaford rlcuBu auB"l lgll arn6ll \tlyi:rlrrr r1¡ 't984 M 5.1 MIn, :¡ La€mlg 1984 M 5.5 lntermountain Selsmlc Belt 150 mllôs ì:ì¡x;¡r¡ \ \ \ f"-: -:r:ü fÏl fuJirJrJlt: U v a Lovalanda BåsinLllv Park 1811 VI 197r M 5.0 Denver tfParker &eÍa Rock M 3.2 !o Vl to {"ì*itulld* Moåb T Gmnd JRclion fr i;,¡ kli¡ t¡ Rangelyn Rio Blanæ (Exploslon) 1Ðf3us.z Jfr ü Rilte Þsltql M MôntÞs€ f:j oið'* ,ti \o*o n Sallda d] u]-: G.. {$ ûtgb Õ69â Q6r Clmsrcn Rldgê Gunn¡sn1S60 LlM 5.5 Pagosa Spr'lngs Waldsn E t f ¡'i-, '.1_ Kmmmllng * N. 1BB2 M€ok€r {$ ç:"-: .: Gold6n D VallnËaglø a Project ?å ?i Tli:t) :_,¿: -;T" 4(lr rulqu*"v VI M 6.2 vil City 1955 Site ôspsn ::ìfi L'T n Cort€u Durâng0 \-l ) a6sd/:1, ,-èi tir*at l-':íai Sp, Wálsoûburg n llrrini¿ad Puebla n Explanatlonr \ Post-Glacíal Faults: \ Fault youngor than aboul 15,000 years. * Largor Historic Earthquakes: Earthquakås with maximum inlenslty gr6åt6r thån Vl or magn¡tude gfêstêr than M 5.0 from 1867 to prassnt. Nuclear Exploslon: Large underground nuclear explosion for natural ga9 reservolr ênhâncêmenl- Hietorlc Seiemlc Zones: Areas wlth historlælly h¡gh ssiBmlc act¡vity. M Local, surface wave or body wave magnitudo Vl Modlfied Mercalli lntoñ$ity Rsferencesl Widmann and Others (1998) U, S. Geological Survey Ëarthquake Gatålogs 50 mi.I r. I Scale: 1 in. = 50 rni, 106 0920 HEPYIORT}I-PAYñ.AI( G€OTECHNICAL c,&Ftectr TCI Lane Ranch Project ¡Faults and Historic Figure 2 AtonBndûe51g/t-¡tÀ's"rlsFirmsÊirerËxplanation:*Þrqþct$ffeEaqleCoflapseGentêr(960 sq, mi.!Shatlow ÊvaporiÞ in EagbVâlley Fomatbn erd EagleValhy Evaporíte.W-rii¿RiverÞùisÊroUplifiVail -PiceanceGlsnwaodNellSpringsRill*&s¡trU)€À,x:¡Þ3SasinGollapseCenter{rt60 sq. mi.)gâsalt10 MilesRe&¡ences:Tweto end O[leß (197t)Kirkham and Scott (2002)Mâ16lêoo)<)(0N(}æTfI!ÉÈRoãszorI'r?mdo:t€oEo=ão-3þÂioô-no6im:f<c,oi :tEg=.d(D(Dv9o(cIı'fa(aEı(¡) NurÉêry ';JQt5 '¡.{ .-iÌ Q16 Qt4"Ego(L ot2 ÇorK af Maf-Plaçed_Fill First Post.Gþcial Terracq $ccot¡d Post.G!qclal Terrace Tl'ürd PoshGlacial Terraee Fourth Pos!Glqcial Terrqçq Alluvial Fans Qr5-7 Qtl o12 o13 Contact: Approximate boundary of map units P1 r E{pjoratorv Pits: Approximate locations. AH Qf 0 Colluvium over Eagle-.Yallev Ëvaporite Modified from Kirkham and Widmann (1997) 400 ft. Explanation: Finedale Oqgvash Terraces: 5 - lowest, 6 - intermediate, 7- híghest Scale; 1 in. = 400 ft. Coñtour lnterval: 1Oft, and 40 ft. March 2008 x06 0920 IJEPI{OfITH-PAht,AK ç€O'IECHNICAL cå6tecn TCI Lane Ranclr Development Project Area Geology Map Figure 4 APPROXIMATE SCALE I":300' 40 tL 1t P NUNSENY PANCEL PITl I collt{}lIÍ I J 53 (\,ø .lfì.'-g al- ¡-{Ø CEMEE Pr'fr( ¿rf r nt rxf L ï. ¿()f ¡$ location of prev¡ous percolation test 10i30/2006 e,'j '[d -t tl' IJ ,1 I Ìç J \ I IL 1 I)P LOCAÏION CIF EXPLORATORY PITS FIGUHE 5106 0920 PIT 1 ELEV.: PIT 2 ÊLËV.= PIT 3 ËLEV.= PIT 4 ELEV.: 0 0 o)oLL I -c o-oâ WC:8.9 DD=96 -2OO=41 (¡) o)u- I E o_off 5 I I +¿=ls -20A:2 5 l I J +¿=oo -200=2 I I +¿=os -200=210l 10 PIT 5 PIT 6 PIT 7 PIT B n 0 c)o LL _c o-'c)ô 5 Ã + o, rDL I E+ta tUô l I I +q:zs -2OA=2 - I +a=or - - -200=3 l 10 10 PIT 9 Pr 10 PIT 11 PIT 12 0 0 0) a)U- I 5 o_ û)ô 5 5 0) 0)IL I -c o_ 0)ol:- +4=54 -200=5 -t I l +4:68 -200: l 10 10 Note: Explanation of symbols is shown on Figure 3 l 1o6oe2o l,-"ffi.^,LOGS OF EXPLORATORY PITS Figure 6 LËGEND: TOPSOIL; organic silty clay, soft, moist, dark brown. SAND (SM-SP ); silty, trace gravels, loose, slightly moist, brown. GRAVEL AND COBBLES (GM-GP); with boulders, clean sand, dense to very dense, slightly moist, light brown to brown, subrounded rock. þ 2" Diameter hand driven liner sample. Disturbed bulk sample. :- Free water in pit at time of excavating. NOTES 1" Ëxploratory pits were excavated on January 15, 2008 with a track excavator. 2. Locations of exploratory pits were measured approximately by pacing from features shown on the site plan provided. 3. Elevations of exploratory pits were not measured and the logs of exploratory p¡ts are drawn to depth, 4. The exploratory pit 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 pit logs represent the approximate boundaries between material types and transitions may be gradual. 6. Water level readings shown on the logs were made at the time and under the conditions indicated. Fluctuations in water level may occur with time. 7. Laboratory Testing Hesults: WC : Water Content (%) DD : Dry Density (pcf) +4 : Percent retained on ihe No. 4 sieve -200 : Percent passing No. 200 sieve ffi [:þÌol t: 1 06 0920 LEGËND AND NOTES Figure 7 Compression 7"(¡(oæ-_looa)ÕO!rmg-o:Ðm{,t>û>ctmFØTPS<ory.¿o3ã c:4-rnqçi s€ å9!Arr5fuJf ou)ro\ (/)-r' R llo'ã(D(o@o)¡cEaloc)f\\\\\=cogH I-J:ıgog)a_o:-JOSJÕ(o1\)OCN€mrf-C)OzCNOrUIoz-{m(n-{nmU)CIU)Tl(oC(Ðæ TIME READINGS U.S, STANDAHD SEFIES CLEAR SOUARE OPENINGS7HÂ 16 MIN,60MtNt9MtN.4 MtN. 1 MtN. #200 /¡100 #50 #30 lt16 #8 #4 318' 3/4" 1 1/2^ 3- 5',6" 8', 10 2A 30 40 50 60 (tz U)Ø L f-z tU C)G LU o_ o LLIz l-- LUE l---z LU()tr tr-l0- 70 BO 90 100 100 90 80 70 60 50 40 30 10 0 .00t .0t2 .005 .009 .otg .037 .ût4 .150 .300 .000 f.rs 2.36 4.73 9.5 t2.5 tg.o 37.5 ?6,2 '152 2û3 127 DIAMETER OF PARTICLES IN MILLIMETERS + ----+-r--4-1- CIAYfO SILT GRAVËL 66 % LIQUID LIMIT O/O SAMPLË OF: Sandy Gravel 7 HR ïME READTNGS 15 MlN.60MtNlgMtN.4 MtN. 1 .001 .002 005.009 .019 .097 .OZ4 .1s0 .300 .600 1.18 2.36 4.75 DIAMETEF OF PARTICLES IN MILLIMETERS coBBl"Es 24 43 0 SAND 32 % SILTANDCLAY 2 % PLASTICITY INDEX O/O FROM: pit 2 at I to B/z Feet U.S, STANDARO SEBIES CLEAR SQUARE OPENINGS O/9, gl4, 1 112" 3u 5"6'MlN. #200 #100 #50 #30 #.t6 #8 tt{ 9.512,519.0 37.5 76,2 fir52 203 I' 100 90 BO CI702ØØ 60 ù< t-- 5o z^ (') 40ffi ô_ 30 10 â20 UJ230at- H4at-250 UJ CJæ60 u-l â_ 70 80 90 100 20 10 0 clÂY10 srlr GRAVEL 15 % LIQUID LIMIT SAMPLË OF: San Gravel SAND B3 % COBELÉS ô//o SILÏAND CLAY 2 % PLASTICIry INDEX O/O FHOM: Pit 3 at 5 to 5 /z Feet 106 0920 GRADATION TEST RESULTS Figure I TIME FEADINGS U,S. STANDARD SERIES 7HR 15 MrN, 60MrN19MtN.4 MlN.1 MtN, #200 #100 #50 #30 r¡16 #B CLEAH SQUARE OPËNINGS CIzı U) o_ t---ztrjOtr UJâ- â UJz t-Liltt-z l.rl Eul0- 10 20 30 40 50 bU 70 80 90 100 l/4 3/8" 314' 1 112' 3u 5"6" 8' 37.5 7A.2 162 203 t00 90 s0 70 60 s0 40 30 20 t0 001 .002 .005 .ocg .019 .037 .o74 ,150 3o0 600 I 18 ?36 4?5 ou ,r.5 tt'o 127 DIAMETËR OF PARTICLES IN MILLIMETÊBS # CLAY 10 $-t GRAVËL 6S % LtoulD LlMlï o/o SAMPLE OF: Sandy Gravel COBBLES SAND 29 ö/o SILT AND CLAY 2 o/o PLASTICITY INDEX o/o FROM: pit 4 at B/z to I Feet U.S, STANDABD SERIËS CLEAR SQUAñE OPENINGS 24 45 0 TIME READINGS 7HR 15 MrN,60M|NJgMlN.4 MlN, 1 MtN. #200 #100 #50 #30 #16 tþ8 #4 3/8" 314' 1 112' 3" 5'6' 8' 100 90 80 (t 704u)û60f þ50ñ O 40ffi o- 30 O IJJz 3üuþz LU G LU n_ 10 20 30 40 50 60 7t BO 90 100 20 10 0 .001 .002 .00s .00g .01g .oa1 .074 .150 .300 600 1.18 2.36 4'75 9'512.519'0 375 -/6'2 pfz 203 DIAMETER OF PARTICLES IN MILLIMËTERS ..t- E CLAYlO SILT GRAVEL 73 % LIOUID LIMIT SAMPLE OF Gravel o//o COBBLES SAND 25 % SILT AND CLAY 2 % PLASTICITY INDEX % FROM: Pit 6 at I to 9 Feet Figure 10GRADATION TEST RESULTS1 06 0920 TIME READINGS 6OMIN1gMIN.4 MIN. 1 MIN. U.S. STANDARD SERIES #100 #50 #30 tÍ16 tÍ8 CLEAH SOUARE OPENINGS *4 3/E 3r'4' 1 112' 3' 5"6" 8', ozı c/) o_ Fzul C)I LUo- l0 a20ul230aF-Lu 40tr F250 LU()E60 UJo- 7A BO 90 100 90 a0 t0 6Ò 50 40 ¡0 20 rô .OO5 .û09 .019 .037 .Otd ,150 .3OO .ô00 1 18 236 475 95 ,r,5 tn0 375 7B-2 ?03152.00r ,00? DIAMETER OF PARTICTES IN MILLIMETERS ctÁY 10 slLT GRAVEL 61 % LIQUID LIM % SAMPLE OF: Sandy Gravel coBBt€s SAND 36 % S|L]-AND CLAY 3 o/o PL"ASTICITY INDËX lO FROM: pit B at 7 Yz ta Blz FeeI U.S, STANDARD SERIES CLEAR SQUARE OPENINGS MlN. #200 #100 #50 #30 *16 #824 45 0 10 TIME READINGS rÉ ljiRrr.r. oor',rr¡lrsMtN.4 MlN. 1 tl| 3/8" gl4', 1 tlz' 3" 5"6" 8', 100 n20 LLJ230 F_LLì 40c F-250 IJJO860 IJJù 70 80 90 80 ("'rc7(Í) cl) ô0 I f-50ñ O40ffi û- 30 90 100 2A 10 0 .00s .00g .019 .037 .a74 .150 .300 .600 1'18 2'36 4'75 9 512.5'19'0 37 5 76'2 Qt52 DIAMETEB OF PARTICLES IN MILLIMETERS 203.001 .002 J-. æ crAY TO SlL t GRAVËL 54 % LIOUID LIMIT O/O SAMPLE OF;Gravelwith Cobble COBBTES SAND 41 % SILT AND CLAY 5 % PLASTICITY INDEX O/O FHOM: Pil 'i0 at 6 to 7 Feet Figure 11GRADATION TEST RËSULTS1 06 0920 TIME RËADINGS U,S, STANDARD SÊRIES CLËAF SOUARE OPENINGS 24HR, 7 HR 0 45 MlN. 15 MlN.60MINJ MIN, l MIN.#200 #10A #50 lt30 *16 #8 tÌ4 $e' 314. 1 u2" 3n 5"6' 8"100 90 .10 80 20 70 o trJzaF LJu. f--z UJ() É.I! 0- 30 40 80 50 40 30 20 (, zıv, ù F-zld()ü Lrlo- 50 60 70 80 IU 90 0 100 .037 .074 , 1 50 .300 .600 1 18 2,36 DIAMETE.ÍI OF PARTICLES IN MILLIMËTEHS 4.75 9.5 19.û 37.5 76.2 |52 203 t¿t,001 .002 .005.009 .019 12.5 CLAY TO SILT COBÊLES GHAVEL 68 %SAND 31 %SILT AND OLAY 1 % LIQUID LIMIÏ %PLASTICITY INDEX % FROM: Pit 12 at 7 le lo I FeetSAMPLE OF: Sandy Gravel Figure 12GRADATION TEST RËSULTS1 06 0920 HEPWORTH-PAWLAK GEOTECHNICAL, INC.TABLE 1SUMMARY OF LABORATORY TEST RESULTSJob No. 106 0920SOIL ORBEDROCK TYPESilty sandSandy gravelGravelly sandSandy gravelSandy gravelSandy gravelSandy gravelSandy gravelUNCONFINEDCOMPRESSIVESTRENGTHATÏËRBERG UMTTSPLASTICINDEX(o/o\LIQUIDLIMTT(o/o\GRADATIONNAÏURALDRYDENSMYGRAVEL("/")SAND(o/r}PERCET¡TPASSINGNO. 200SIEVE4t2222J5I328329253641JI6615697361546896NATURALMOISTURECONTENT(a/o)8.92.7SAMPLE LOCATIONPITDEP-TH2r/28 - 8r/z5-SVzïVz -98t/2 - g7t/2 - 9Vz6t/z - 77Yz-8I2J46I10I2