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Home My WebLink AboutPreliminary Geotechnical Study 03.14.2008- FIEPWCIRTH - PAWLAK GECITECHNICAL I irl,rr,,ttll l'r¡tt,l.rli (. ir,ur'¡ lr¡u,.rl it¡. i{_-t.l{l r. ¡ ,r¡¡r'. lì,r:i,.1 | -i.l t,i|,.:l'¡rtrrrl ll.l'i¡l.u¡, {'rir'¡':r.i', iiItxI I f'h.,n*::,!iil,9+ i., ;(ti¡i l:rríi (, i{l-r¡-{ i,¡il il i' I¡ii¡ I I : lì | ìJ!-r,i]il r|;,ç,'1 q ¡-- | ¡..,,,, t H l-;¡¡'l:r¡. ìr-ìl-i'i4I -7 I l'¡ PRELIMINARY GEOTECHNICAL STUDY PROPOSED TCI LAFIE RANCH SUBDIVISION HTGH\ryAY 82 AND EAST OF COUNTY ROAD TOO GARFIELD COUNTY, COLORADO JOB NO. 106 0920 MARCII 14,2008 PREPARPD FOR: TCI LANE RANCH, LLC C/O NOBLA DESIGN STUDIO ATTN: JON FR-EDERICKS, ASLA 1935I HIGH\ryAY 82 CARBONDALE, COLORADO 8ró23 l.iIyc'r't þrr¡¡c rl7{:l--{,,1i- |'ll-,'la( ì,rl,r¡'i¡¡.111 S¡'ringr 7 l!)'{i ì 1-iii1l * TABLB OF CONTENTS PURPOSE AND SCOPE OF STUDY STTE CONDITIONS,. REGIONAL GEOLOGIC SETTING.",......... PROJECT SITE GEOLOGY RIVER TERRACES AND DEPOSITS...... EAGLE VALLEY EVAPORITE........ GEOLOGIC SITE ASSESSMENT.....,... RIVER FLOODING SINKHOLES ............... EARTHQUAKE CONSIDERATIONS RADTATION POTENTIAL FIELD EXPLORATION SUBSURFACE CONDITIONS.......... PRELIMINARY DESIGN RECOMMENDATIONS,. FOLINDATIONS BELOW GRADE CONSTRUCTION... FLOOR SLABS..".. SURFACE DRAINAGE ..........,.... PAVEMENT SECTION LIMITATIONS ....... l- -2- 3- _4_ -¿._ ! _{- -5- ........... - 6 - ',.,'..'....'.'. - 8 - .,.,............ - I - -l _ _o_ 9- -o- -i0- ................ - 10 - REFERENCES FIGURE 1 _ PROJËCT SÏTE LOCATION FIGLIRE 2 _ GEOLOGICALLY YOLTNG FAULTS AND LARGER HISTORIC EARTHQUAKES FIGURE 3 - WESTERN COLORADO EVAPORITE REGION FIGURE 4 _ PROJECT AREA GEOLOGY MAP FIGURE 5 _ LOCATION OF EXPLORATORY PITS FIGURE 6 _ LOGS OF'EXPLORATORY PITS FIGURE 7 . LEGEND AND NOTES FIGURE 8 - S\A/ELL-CONSOLIDATION TEST RESULTS FIGURES 9, IO, II &,12- GRADATION TEST RESULTS TABLE I- SUMMARY OF LABORATORY TEST RESULTS PURPOSE AFID SCOPE OF STUDY This report presents the results of a prelirninary geotechnical study for the proposed residential subdivision at TCI Lane Ranoh loeated north ofthe Roaring Fork River and east of the Blue Creek Ranch Subdivision, Carfield County, Colorado. The project site is slrown on Figure 1. The purpose ofthe study was to evaluate the geologic and subsurface conditions and their potential impact on the project. The study was conducted in accorda¡ce with our proposal for geotechnical engineering services to TCI Lane Ranch, LLC, clated December 20, 2007. \Ve previously conducted percolation testing for a septic system design on the property and presented our findings in a report dated October 31, 2006, Job No. 106 0920" A field exploration plogram consisting of a reconnaissance and exploratory pits was conducted to obtain information on the site a¡rcl subsurface conditions. Samples ofthe subsoils obtained during the field exploration were tested in the laboratory to deternrine their classification, cornpressibility or swell and other engineering characteristics. The results of the field exploration and laboratory testing were analyzed to develop recommendations for project planning and preliminary design. This report sumtnarizes the data obtained during this study and presents oul' conclusions and recommendations based on the prnposed development and subsurfhce conclitions encountered. SITE CONDITIONS The TCI Lzure Ra¡ch covers about 100 acres and is located in the Roaring Fork River valley about three and one-half miles upstream of Carbondale, see Figure 1. The properly lies to the north of the river and is entirely on the nearly level valley floor. The valley floor has an âverage slope of about 2 percurt clown to the west. It is made up of several rivet terraee levels that are separated by low escarpments. The escarpments are typioally about 6 to 20 feet high and have slopes of about 50 to 70 percent. The tenace surfhces lie between about 4 to 46 feet above the river, The Frontage Roacl for Highway 82 is locatecl along the northern property line. Patts of the southem propefty line are in Jol¡ No. 106 0920 eåFtecn -2- the Roaring Fork River channel. The Blue Creek Subdivision borders the property on the west arrd rural homes and agricultural lnnd are located on the propertics to the east. At the time of this study several houses and ranch buildfutgs were located in the east-ce¡rtral pafi of the TCI Luue Ranch. Muçh of the ranch is irrigated ltay lields and pasture which ate located mostly on the higher teuace surfaces. Cottonwood trees, other trees and brush are typical of the vegetation on the lower teffaces. Poorly drained wetlands are also present on the lower terraces. PROPOSND DEVELOPMENT 1'he proposed developnrent at the TCI Lane Ranch will be mostly a residential subdivision as shown on Figure 4. A plant nursery will be located in the northwestern part ofthe property. The lowest teltaces along the river will not be developed and undeveloped grouncl will remain along Highway 82. Eighty-nine residential lots are proposecl. Other development facilities will include a network of streets, a community park and other community facilities. If development plans change significantly from those describetl, we should be notified to re-evaluate the recommendations presented in this repofi. REGIONAL GEOLOGIC SETTING The project site is in the Southem Rocky Mountains to the west of the Rio Grande rift and tn the east of the Coloraclo Plateau, see Figure 2. The site is in the western Colorado evaporite region and is in the Carbondale collapse center, see Figure 3. The Carbondale collapse center is the westem oftwo regional evaporite collapse centers fur western Coloraclo. It is an irregular-shaped, northwest trencling 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 occurred during the past l0 million years in the vicinity of Carbondale as a result of dissolution and flowage of evaporite from beneath the regions (Kir-kharn nnd Others, 2002). The evaporite is rnostly in the Eagle Valley Evaporite with some in the Eagle Valley Fornration. The Eagle Valley Evaporite is the near surface formation rock below the surficial soil deposits at the project site, It clops Job No. 106 0920 c$tectr -3- out on the steep valley side to the south of the river, see Figure 4. Much of the evaporite related subsidence in the Carbondale collapse center appears to have occur¡ed witlrin the past 3 million years which also corresponds to high incision rates along the Roaring Fork, Colorado and Eagle Rivers (Kunk and Others, 2002), This inclicates that lorig-term subsidence rates have been very slow, between about 0.5 and I .6 inches per 100 years. It is uncertain ifregional evaporite subsidence is still occun:ing or if it is curently inactive. If still active these regional deformations because of their very slow rates should not have a significant impact on the propose clevelopment at the TCI Lane Ranch. Geologically young faults related to evapodte tectonics are present h the Carbondale collapse center but considering the nature of evaporite tectonics, these fault are not considered capable of gerierating large earthquakes. The closest geologically young faults that are less than about 15,000 years old and considered capable of generating large earthquakes are located in the Rio Grancle rifr to the east of the project site, see Figure 2. The northern section ofthe Williams Fork Mountains läult zone Q50 is located about 60 miles to the nor-theast and the southern section of the Sawatch fault zone Q56b is located about 60 miles to thc southeast. At these distances large earthquakes on thesc two geologically young fault zones should not produce strong ground shaking at the project site tlrat is greater than the ground shaking shown on the U. S. Geological Survey 20AZ National Seisrnic Hazarcls Maps (Frankel and Others, 2002). PROJECT SITE GEOLOGY Tlre geology in the project area is shown on Figure 4. This map is basecl on our f,reld observations and is a modification of the regional geology nrap by Kirkham and Widmann (1997). Near surface formation rock is the middle Pemrsylvanian-age, Eagle Valley Evaporite. This regional rock formation was deposited in the central Colorado trough durùrg the Ancestral Rocky Mountain orogeny about 300 million years ago. At the project site the evaporite is covered by a series of Roaring Fork River tenaces and deposits that are associatecl with cyclic periocls of cleposition and erosion related to glacial ancl interglacial climatic tìuotuations during about thc past 35 thousancl yeals. .lob No. 106 0920 cå&ectr 4 RIVER TERRACES AND DEPOSITS Remnants of seven river tenace levels (Qtl through Qt7) are present at the project site. The lower four terraces are probably related to post-Pinedale climatic fluctuations during the past 15 thousand years. Terrace Qtl lies within 4 feet ofthe river. Terrace Qt2 lies about 6 feet above the river, terace Qt3 lies abotrt 12 feet above the river and terrace Qt4 is about 22 feet above the river. The Qtl terraces are small river bank terraces and channel bar deposits. The Qt2 temaces are olcl abandoned river channels that lie below the Qt3 terrace surface, The three higher tenaces are probably associated with the late Pleistocene-age, Pinedale glaciations between about l5 and 35 thousancl years ago. Terace Qt5 lies about 38 feet above the river, tenace Qt6 lies about 40 feet above the river and tenace Qt 7 lies about 46 feet above the river. Our exploratory pits show that the alluvial deposits below temace levels Qt3 through Qt7 are similar. They consist of a thir¡ less than 1-foot thiek to 3-foot thick, topsoil formed in sofi, silty clay over-bank deposits. The over-bank deposits overlie river alluvium that consists of rounded gravel- to bouldcr-size rocks in a relatively clean sancl matrix. The river alluvium extended to the bottom of thc exploratory pits that werc excavated to tlepths of around 9 fset. Judging from water well records ùr the Colorado State Engìneer's data base the river alluvium is probably in the range of 40 to 50 feet deep in the project area. EACLE VALLEY EVAPORITE The Eagle Valley Eva¡rorite unclerlies the Roarirç Fork River alluvium in the project area and as discussed abclve rnay extencl to depths of 40 to 50 feet below thÊ terrace surfaces. Tlte Eagle Valley Evaporite is a sequence of evaporite rocks consisting of rnassive to laminated gypsut& anhydrite, and halite interbedded with light-colored nrudstone, füre- grained sandstone, thin limestone and dolomite beds and black shnle (Kirkharn and tl/idmarul 1997). The evaporite minerals are relatively soluble in circulatíng ground water ancl subsurface solution voids and related surface sinkholes are locally present in these rocks ttu'oughout the westem Colqrado evaporite region where the evaporite is near Job No. I t16 092U cå8æcn -5- the surface, see Figure 3. Sinkholes were not observed at the project site cluring our field work but the snow cover at that time may have obscured sinkholes if present. GEOLOGIC SITE ASSESSMENT Geologic conditions that could present an unusually high risk to the proposed 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 rnitigations to reduce the risks are cliscussed below. Geotechnical engineering design considerations are presented in the Pleliminary Desígn Recomrnendations section of this repoú. RIVER FLOODING The lorv lying terraces along the Roaring Fork River may be subject to periodic flooding during high rivet llows. The hydrologic study conducted far the project stonn w¿rter management plan design should evaluate the potential tor river flooding and possible methods to plotect project facilities from an appropriate design fìoocl on the river. STNIil{OLES Geologically young sinkholes are present in the western Colorado evaporite r-egion mostly in areas where the Eagle Valley Formation and Eagle Valley Evaporite are shallow, see Figure 3. In this region a fcw sinkholes have collapsed at the gtound surface with little or no waming during historic times. This indicates that infrequent sinkhole fonnation is still an active geologic process in the regíon. Evidence of sinkholes was not obsen'ed at the project site during our field reconnaissance or aerial photographs review but coulcl har.,e been obscured by the snow cover. A field t"eview to look for sinkholes in the proposed building area should be made after the site is elear ofsnow cover. Although geologically active h the region , the likeiihood that a sùrkhole will development during a reasonable exposllre titne at the project area is consiclerecl to be low. This inference is ,lob No. 106 0920 cåSteclr -6- basecl on the large extent of sfurkhole prone areas ir the r:egion in comparison to the small number of sinkholes that have developed in historic tirnes. 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 related prublerns are encountered during site specific soil and forurclation studies fbr the houses and other movement sensitive faculties, zur alternative building site should be considered or the feasibility o f rnitigation evaluated. Mitigation measures could include: ( I ) a rigid mat foundation, (2) stabilization by grouting, (3) stabilization by excavation ancl backfilling, (4) a deep foundation system or (5) structural bridging. Water features should not be consiclered close to building sites, unless evaluated on a site specific basis. The houre owners could purchase special insurance to reduce their potential risks. Prcspective owners shoulcl be aclvised of the sinkhole potential, since eally detection of builcling clistress and tirnely remedial actions are important in reduoing the cost of building repair should an undetectcd subsurfacc void start to devclop into a sinkhole altcr construction. EARTHQUAKE CON SIDERATION S Historic eartlrquakes r,vithin 150 rniles of the project site have typically been moderately strong with magnitudes c¡f M 5.5 and less and maxirnurn Modified Mercalli Intensities of V[ ¿¡u] les$, suu Figure 2, The lalgcst historic uarthquuke irr l.he project region occurred in 1 882, lt was lucated in the nurlhenr Frunl Rauge about I 15 rniles to the nofiheast of the project site zurcl had a estunated magnitude of about M 6.2 ancl a rnaximum intensity of VII. I{istoric ground shaking at the project site associated rvith the 1882 and ths other larger historis earthquakes in the region cloes not ôppear to have exceedecl Modified Mercalli Intensity VI (Kirkham zurd Rogers, t985). Moclified Mercalli lntensity VI ground shaking should be expected during a reasonable exposure tirne for the houses and other project lacilities , but the probability of stronger ground shaking is low. Intensity VI ground shaking is felt by rnost people and causes general alarnl but results in negligible tlamage to stn;ctures of good clesign ancl construction. Job Nn. l0ô 092ü <;åfrecrr -7 - The houses and other faoilitiss subject to earthquake damnge should be designed to withstantl moderately strong gpound shaking with little or no damage anil not to collapse under stronger gnund shaking. For.firm roclr sites with shear wave velocities of 2,500 fps in the upper 10û feet, the U, S. Geological Survey 2002 National Seismic Hazard Maps indicate that a peak grrund acceleration of 0.069 has a 10% exceedence probability for a 50 year exposure time and a peak grnund acceleration of 0.239 has a2o/o exceedence probability for a 50 yeff exposure time at the ptoject site (Frankel and Others, 2002). This conesponds 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,.firnt rack sites as clescribed in the 2006 International Building Code unless site specific shear wave velocity str"rdies show otherwise. RADIATION POTENTIAL Regional studies by the Colorado Geological Survey indioate that the closest radioactive mincral occun'ences to the project site are greater that twenty miles fiom the sitc (Nelson-Moore and Others, 1978). R¿rdioactive mineral occuffences âre present in the Aspen-Lenado rnining distriet to the southeast and on the southwest flank ofthe White River uplift to the northwest. Regional studies by the U. S, Geological Survey (Dubiel, 1993) fbr the U" S. Environrnental Protection Agency (EPA) indicate that the prnject site is in a moderate ratlon gas potential zone. The 1993 EPA regional radon study considered data fîom (l) indoor radon surveys, (2) aedal radioactivity surveys, (3) the general geology, (4) soil perrneability estimates, and (5) regional architectural practices. lt is not possible to acourately assess future radou cr¡ucentrations in builditgs before tliey are constructed. Accurate tests ofradon concentrations can only be made when the buildings have been completed. Because of this, new builclings in modelate to high radon areas âre often designed with provisions fcrr ventilatic¡n of the lower enclosecl areas should post constructio n testing show unacceptab le rarJon concentrat ions. Job No. l0ó 0920 cå&ecrr -8- FIELD EXPLORATION The tield exploration for the project wns conducted on January l0 and 15, 2008. Twelve explorntory pits were excRvated at the locations shown otr Figure 5 to evaluate the subsurface conditious. The pits were dug with a lrackhoe and were logged by a representative of Hepwortli-Pawlak Geoteclurical, Inc. Sarnples of the subsoils were taken with relatively undisturùed and distutbed sampling methods. Depths at which the samplos were tnken aro shown on the Logs of Explorntory Pits, Figure 6. The sanrples were retumed to our laboratory tbr review by the project engineer and testing. SUBSURT'ACE CONDITIONS Graphic logs of the subsurface conditions encountered at the site are shown on Figure 6. The subsoils consist of about lz to 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 remaining pits. Pit 3 contained a lcns of slightly gravelly sand from 4 to SYz feet. Laboratory testing performed on samples obtained from the pits included natural moisture content and density and gradation zuralyses. Results of swell-consolidation testing perfornred on a relatively undisturbed sarnple, presented on Figure 8, indicate moderate compressibility under conclitions of loading and wetting, Results of gradation analyses perfonned on large disturbed samples (rninus 3 to 5 inch fraction) of the natural coarse granular soils arc shown on Figures 9 through 12. The laborotory testing is summüized in Table L No free water was encountered in the pits at the time of excavation and the subsoils were slightly moist. PRELIMINARY DESIGN RECOMMENDATIONS The conclusions and recommendations presented below are based on the proposed development, subsurface conditions encountered in the exploratory pit, and out' experience in the area. The recommcrrclations arc suitablc for planning nnd prclirninary clesigrr but site speeific studies shoulcl be conducted for individual lot developmenT. .lob No. 106 0920 cå&*crr -9 FOLTNDATIONS Bearing conditions will vnry depencling on the specific location of the building on thc property. Based on the ¡ratute of the proposecl constructic¡¡t, sprencl footings bearing on the natural granular soils should be suitable at the building sites. trVe expect the footings can be sizecl for an allowable bearing pressure in the range of 1,500 psf to 3,000 psf Compressible silty sands encountered in building il'Èås may need to be removed or the footings designed accordingly âs pûrt ofthe site specific lot study. Nested boulders and loose matrix soils may need treatment such as enlarging footings or placing compaoted structural fìll. Foundation walls should be designed to span local anomalies and to resist lateral ear-th loadings when acting as retaining stnrctures. The footings should have a minimum depth of 36 inches for frost prntection. BELOW GRADE CONSTRL]CTION Free water was encountered in some of the exploratory pits and it has been our experience in tlre area that the water level can rise and local perchecl grnundwater can develop during times of seasonal runoff and heavy irrigation. In general, all below grade areas should be protected ûom wetting and hydrostatic pressure buildup by use of an underdrain system. We recornmend that slab-on-grade floors be placecl 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 irnpacts on prol:osed development should be evaluated as part of the site specific building study. FLOOR SLABS Slab-on-grade constructio¡r should be fèasible for bearirrg on the natural granular soils below the topsoil. There coulcl be some post construction slab settlement at sites with cornpressible silts and sands. To reduce the effects of some differential movement, floor slabs should be separated from all bearing walls and colururs rvith expansion joints. Floot slab control joints should be used to rcduce damage due to sluinkage cracking. A Job No, 106 0920 cå6te,cn -10- minimum 4 ineh thick layer of liee-draining gravel shoulcl underlie builcling slabs to break capillary water rise and facilitate drainage. SURFACE DRAINAGE The grading plan for the subdivision should consider r:unoff tlunugh the project and at indívidual sites. Water slrould 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 h'om the buildittg tbr a distance of at least l0 feet. Roof dolvnspouts and drains should discharge well beyond the lirnits of all backfill aud ianclscape in'igation should be restricted. PAVEMENT SECTION The near surface soils encounterecl in the exploratory pits below the topsoil typically consisted of silty sandy gravel. The pavement section for the site access roads can be taken as 3 irrches of asphalt pavement on 8 inches of Class 6 aggregate base course for preliminary design puJ:poses. The subgrade should be evaluated for pavement suppofi at the time of construction. Subexcavation of the topsoil and fine-grained soils and replacement with coarse granulal subbase rnaterial may be neecled to acl'rieve a stable subgrade in some areas. LIMITATIONS This study has been conductecl according to generally acceptecl geoteclrnical engineering prìnciples ancl practices in this area at this time. Vle make no waffanty either express or irnplied. The conclusions and recomtnendations subrnittecl in this report are based upon the data obtained f,nm the field reconnaissance, review of published geologic reports, the exploratory pits located as shown on Figure 5 ancl to the depths shown on Figure 6, the proposecl type of construction and our experience in the area. Our consulting services clo not include detennining the ptesence, plevention or possibility of rnold or other hiological contaminants (MOBC) cleveloping in the future, If the client is concerned about MOBC, then a professional in this special field of practice should be consuìted. Our findings J¡rb No. 106 {,j920 cåFt=cl'r - 11- include interpolation and extrapolatiou ofthe subsurfàce conditions identi{ied and tlle exploratory pits and variations in the subsurface conditions may not become eviclent until excavation is performed" tf conditions encountered cluring comtruction appear clifferent from those described in this report, we shoulcl be notifiecl so that re-eyaluation of the reconrmendations rnay be macle. This report has been prepared for the exclusive use by our client for planning and preliminary design puryoses. Vy'e are not respotxible for technical interpretations by others of our infcrrrnation. As the project evolves, we should provide continued consultation, conduct additional evaluations and review and monitor the implementation of our recommendations. Significant design changes may require atlditional analysis or modi{îcations to the recommendations presented herein. "We recommend on-site obsewation of excavations ancl foundation bearing strata and testing of structural fill by a repressntative o f the geotechnical engineer. Respectfirlly Submitted, HEPV/ORTH - PAWLAK GEOTËCHNICAL, INC. Scott V/. Richards, E.I. Reviewed by: Steven L. Pawlak, P.E S\MR/vad Job No. 106 09?0 cåFtecn -12- REF'ERENCES Dubiel, R. F., I 993, Preliminary Geolagic Radan Poten.tial Assessm.ent of'Colorado in Geologi,c Radon. Potential EP,4 Region 8, Colorado, ltlontqna, North Dakotc¿, South Dalcotct, Utah and þú\amíng: U. S. Geological Srwey Open File Report 93- 292-H. Frankel, A. D. and Others, 2002, Docttmentatian.for th.e 2002 Update of the Natíonal Seismic Hazard Maps,'U. S. Geological Suruey Open File Report 02-42A. Kirkham, R. M. atrd Rogers, W. P., 1985, Calorado Eurthquake Data and InterpretütÌons 1867 to 1985: Colorado Geologícal Survey Bulletin 46. Kirkham, R. M. and'Widmatm, B. L.,1997, Geology Map of the Carbandale Quadrangle, Garfield County, Colorado: Colorado Geological Survey Open File 97-3. Kirkham, R. M. and Scott, R. 8., 2tA2,Intraductíon to Late Ce.nozoic Evaporite Tectonism ancl Volca¡tism in lHest-Central, Colorado, in Kirkharn R. M., Scott, R. Job No. 106 09?0 cåFtecrr Li.,lAil;i; rs(¡d.iliiII¡;J\i. ':.JI.t'.1itJ.\''\,.. ,...F* .i.-tI,t'I,t ;iiroi¡i ..,.-J--:- r.-*,l"å,i,,',;'.,, 'I, { ,., '"'"li{1,;, ì. -,',i ;,\' .lI' uijo'ì*., , .r\. ìì,.._; ".¡r\''Jf,.ir1,ì...,,'1It,'.l'I'^'.:.l: 'I l..f:-. Ì:.:Ì-.ìt!{'!'i. ,¡ri'-t.-.:r-r 1:. f'-Iril¡)ùnll-:i-t.'ì. .-:..i ''"'u*i,¡nÍnN I¡ l['-&r.--|l¡i,1S¡r ¡l-{f)00â0'$ flþ e leÃJelul Jnofuot'u 000Ê = 'ul I :âlBcst orn6Hl'eford qcuBu euel lctuol¡Eco-l olls0¿60 90r.tlcêt5EìÐ 6.1 \Ù =l lntermountaln Salcmlc Bôlt Wv¡r¡fiiirr¿ Låramio Mtn. t9M M 5.5 WY 160 mllåD 13,âr;in l¡ "î Ìå. *\j t.] r:: À¡icrcjl* v ¿.I¡.,* t Lovolsndt L¡lv Pârß r8?1 vt Baoln M 5.0 I Vl toVll M 3.2 to D6nvsr EPârkar C?*u" Rock i-)olcrarJc Belt Mo¡b n srand.J[*ctbn i.:l¿lle*t; t RiÍs Rull¡on * ( Exploslori) 1989 M ı.3 $. Dollqf Rangdy rJ Rlo Bl¡nco (Explosþn) 1973uo.r f; MontMn oñ-* .È, ,¿l ìì oor té.ü Q69t ûô9b !!j.l D Sallda Prgo¡r spring¡ W6ldcnü Meeksr GoSen 0 Vai¡{f Esglo a P¡oi€ct '?i.),..à, ';ti {)a¡ C¡nåron 1960 M 6.5 '+ '.]jiiì mff*, vl 1965 M iíì-f .a -;l': Kmmmtlng .1 N" vü cily ,.rì i] Ç- r;-. (lt :1 Sits #"p"n E "ì i¡? Rldgo Gunnleon ca u1' torte" Durengo CO oü9d.¿.4 üt..',iii i:'!:,: I I Sp. Puoblo WÉlsonburg U úTrln¡dad Explanatlon; \ Post.Glacial Faults: \ Faull youngsr lhan about 1 5,000 y€ars. Larger Historlc Earthquakes : Earthquakes wlth maxlmum inten6lty gr€at€r lhãn VI or msgniludê greât€r than M 5.0 frDm 1867 lo pressnt. * Nuclsar Explosion: Large underground nucl€ar sxploslorr for naluml gas rosorvoir enhanc€m€nl. Histor¡c Selsmic Zones: Arså$ wlth histor¡oålly high ss¡Bmh åctlvily. M Locsl, surfâcè wsve or body wave magnitudeVl Modlfled Mercalll lntenslty Referenceo: W¡dmânn and Others (1098) U. S, Geological Survey Earlhquako Catalogs 0 50 mi.tt, Soale; 1 in. æ 50 mi. 106 0920 HEPSþRlH-PAtil.¡r( GEOIECf tNtCA! eåFtecr'Figure 2TCI Lane Ranch ProJect Y Faults and Historic Explanation:* pOraSitêShalbrv Evapaf/te in EãgleValley Formation and EagleValley Evaporite.EaqlecoÏlaoseCenter(960 sq. mi.)Ur'hiteRiverût-.secUpl'ftYaii 6PiceenceGþñuJoodÌl¿r.lRiíiÊsi'ilójìÌF33ÐasÍriGarboCollapseCenter(¡t60 sq. ml.)10 MfesReferencss:Tweto and Others (1978)Kirkham and Scott (20û2)f{ffSridgeYioicrit'í19,"'¡!¡5ç{¡¡.^' r.rsgi.rñsËagìefu4ãrblcO6)()(oN)(>IÌfsII?Fsotrltır0t8{trn:rãotno-{3cio-*þdo*æeq)rnJ<o$:tEp-. cioo¡9(D(o¡fr(llLo-c'J . - l. i:::_ L.,':] -. -'ì'. i.- : 1r. Qt5 I Pl ".ir, Blue Creek Ranch i:ì i:, i.l L {ì4r Q14ftcol! t, ,ì,ø i ßr3iì -. ., , ìi Q12 Q12 çorK Qt3- Qr1 : ,.t, ar Man'Placod Fill Firsl Pget.Glacial Terace 9econd Pgst.Glaclal Terrace ïhlrd Post-Glaclal Terrage Fourth Post Glaclal TerraEe Alluvial FanE Q{5-7 Pinedale Outwaah Terraces: 5 - lowest, 6 - ¡ntermediate, 7- highest Colluvium over Eagle Valley Evaporite gqntact: Approxlmato boundary of map units. Exploratory Pits: Approxímate locatíons. Qr1 Qr2 Qt3 Q14 QT 0 P1 I 400 ft. Moditicd from Kirkham and Widmann (1997) Explanation: Scale; 1 in. = 400 ft^ Contour lnterval: 1oft. and 40 ft. March 2008 106 0920 HEPIYOfi IH-PAIìTJÀ¡( OEO¡ECIiNICAL e&Fteclr TCI Lane Ranch Development Area Geology MapProject Figure 4 APPROXIMATE SCALE '1 " : 300' P¡804. I \ IL )J t7 J 4O t-1 I l I I t. NUÊSþIIY PAñI}TL PITl I It I J E)- È<{(, þ¡" .ru{ U) c0r!t¡\l¡Y ofil'ÊA r l 't I I PÁA(J LU(f da t. IIr--1Lr l. Lilf ı9 \J f,l r d8 location of previous percolation test 10/30/2WLÔi ?O '\' r-1h! BzL--r I LOr ,t3 1-t I r o¡ 16 I LOCATION OF EXPLORATORY PITS FIGURE 5106 0920 PIT 1 ELEV.: PIT2. ELEV.= PIT 3 ELEV.= PIT 4 ELEV,= 0 0 (l) o)u- Ig o- o)Õ WC*8.9 DD=96 -204=41 5 0) 0)lr- Is o.(¡) Õ 5 I f +q=ts -200=2 l I I +¿*oe .200=2 I I +¿=og -200:2 10 I 10 PIT 5 PIT 6 PIT 7 PIT 8 0 0 o)oLL c ct 0)Õ 5 ËJ ooL I c o-oa -l I +4:61 -200=3lI I +¿=zg -200=2 I l 10 10 PIT 9 PIT 1O PIT 11 PIT 12 0 0 d) o)IL -c o-oo 5 5 0) c)tL -c o_uÊl -l I l +4:68 -200*1*4*54 -200*5 10 10 Note: Ëxplanation of symbols is shown on Figure 3. l 106 0920 ,",ffi*l LOGS OF EXPLORATORY PITS Figure 6 LEGEND TOPSOIL; organic silty clay, soft, moist, dark brown. SAND (SM-SP ); silty, trace gravels, loose, slightly moist, brown, GRAVËL AND COBBLES (GM"GP); with boulders, clean sand, dense to very dense, slightly moist, light brown 1o brown, subrounded rock, þ 2" Diameter hand driven liner sample Disturbed bulk sample. _ Free water in pit at time of excavating. NCITES: 1, Exploratory pits were excavated on January 15, 2008 with a track excavator. 2, Locations of oxploratory pits were measured approximately by pacing from features shown on the site plan provided. 3. Elevations of exploratory pÌts were not msasured and the logs of exploratory pits arc drawn to depth, 4. The exploratory pit locations and elevations should be oonsidered aocurate only to the degrec implicd by the mcthod used, 5. The lines belween materíals shown on the exploratory pit logs represent the approximate boundaries between malerial types and transitions may be gradual, 6. Water level readings shown on the logs were made ât the time and under the conditions indicatecl. Fluctuations in water level may occur with lime. 7. Laboratory ïesting Results; WC : Water Content (%) DD : Dry Density (pcf) +4 : Percent retained on the No. 4 sieve -200 - Percent passing No.200 sieve ffi t: 1 06 0920 LEGEND AND NOTES Figure 7 co(Jc)o_o"Qco@o)0)(Jo)il ãtLC/J \Nc-^O ác\rE il c,l tt.Y\L,ÉE *c¡9u'==h(DL#ö-g;Õ>ko>ôùiù\\\\\N\c''6(t,(l)h9):FLcñ=oãA)o ã3ooogc;ûYtiJE:fU)(nUJE.o-oLUJa-o-vro()C\Jfrj70 UO|SSOJdUJOS@f.-@6)OñJo)O(()OU)TfU)UJEFU)t_uÞzotrcl:]o(nzo()IJJul=CDcooLfcT)ir (tz U)(n L f-z UJ() æ LU o_ 10 20 LJtl-lz. 30 t- H40 Fzs0 LU(Jrr60 LU ô_ 70 BO 90 100 TIMË RFADINGS 6OMIN1gMIN,4 MIN, J MIN U.S. STANDABD sER'ES #200 #100 #50 #30 #16 #8 #4 CLEAR SQUARE OPENINOS 3/g JlA, 1 1/2" 3- 5"6" 37.5 742 100 s0 80 70 80 50 40 30 fr r0 o 001 .00e ,oos .oô! .ût9 .037 .07i ,150 30o ô00 1.lB 2.36 i'75 9.5 12.s 19.0 r52 83 ÐIAMETER OF PARTICLËS IN MILLIMFIEBS CI.AY TO SILT I .= aqND I ßMvIf___J coÊsLEs GHAVEL 66 % LIQUID LIMIT O/O SAMPLE OF: Sandy Gravel 7 HR T|ME READTNGS 15 MlN.60MtNlgMtN.4 MtN. 1 SAND 32 % SILTANDCLAY 2 O/O PLASTICIry INDEX O/O FHOM: Pit1 atB to B)zz Feet #4 8',45 0 10 MlN. #200 #100 # U,S. STANDARD SEFIES 50 #30 rN16 #B CLEAB SQUARE OPENINGSg/S" gt1, 1 112' 3" 5"6' e.q2,51e.0 37.5 76.2 fir52 100 90 80 C5nZ U)u)60s t-uofr O40ffi o* 30 20 o LUzat--tUE. F- tU(JEtrl Õ_ 20 30 40 50 60 7Q 80 90 100 10 .00.1 .002 .00S .009 .019 o37 .074 .1SO .300 .600 1.18 2.36 4.75 DIAMETER OF PARTICLES IN MILLIMETERS 203 .--..-1-+-_t-,¿ ---|È_-rl--}- -t-Êt+ -*___,+___{--{_ ñ.--_-# cl.{Y lð iirli GRAVEL .I5 % LIQUID LIMIT SAMPLE OF:Gravel o/o coBBrÊs SAND 83 "/" SILTANDCLAY 2 % PLASTIÇITY INDEX VO FROM: Pil S al5 to 5 Feet 106 0920 GRADATION TEST RESULTS Figure I TIME READINGS U.S. STANDARD SERIES CLEAR SOUARE OPENINGS 7HR l5 MlN. 60MtN:gMlN.4 l MtN. #200 #100 #s0 #30 #18 #8 #4 3/8,' 314' 1 1t2' s', 5"6" 8" (5zı U) ô_ t--z tlJ O ccr!â- t0 o20 IU230 H40 F"250tuOü60 UJ0- r0 80 g0 100 r@ 90 gc 70 60 50 ¡0 30 t0 .ms .ooÊ .01s .067 .02{ .1go '3oo 600 1'1ô e36 A75 9'5,z.s rg.0 3?.5 78.2 152 ?03 .00 I .ùo2 127 DIAMETER OF PABTICLES IN MILUMETERS # ctAY'IO Sìtl COSBLES #4 3/8" gl4' 1 112' 3' 5'6' 8'24 45 0 GRAVEL 69 % LIQUID LIMIT % SAMPLE OF: Sandy Gravel TIME READINGS7HR 15 MIN,6OMIN'gMIN,4 MIN, 1 SAND 29 % SILT AND CLAY 2 O/O PLASTICITY INDEX O/" FROM: pit 4 at Blz to 9 Feet U.S, STANDAHD SERIES CLEAB SQUARE OPENINGS MlN. #200 #100 /150 #30 #16 #8 100 s0 80 CItoz U)Ø60f t--5oñ () 40ffi 0- 30 o LLIz t--tUE l--ztrl()E LUo- 't0 20 30 40 50 60 70 80 90 100 20 10 0 .00r ,002 .005.00g "019 ,0gZ .OTA .'150 .300 600 1.18 2,36 4.7s 9.q2.519'0 375 76'2 n+52 203 DIAMETER OF PARTICLES IN MILLIMETËBS tLÁY tÕ s['r GRAVEL 73 % LICUID LIMIT SAMPLE OF:Gravel % COBBLES SAND 25 % SILT AND CLAY 2 % PLASTICITY INDEX % FBOM: PiÎ6 at 8!e lo I Feet Figure 10GRADATION TEST RESULTS1 06 0920 TIME READINêS 7Hn't5 MlN,60MlNl 4 MIN. 1 MIN,#2Q0 *1 U-S, STANDABD SERITS #50 $3A #16 #B CLEAR SQUABE OPËNINIGS 3/S' 3l4u 1 1/2- 5"6" 8" ozıv) 0- Fztrl C)E LUù ÕIJz t-'- l_tl E. F--z[! cc LJ"¡fL 10 20 30 40 50 60 70 80 90 100 lm 80 70 ßû 50 {0 å0 ñ 10 ,0ô'r .00e .ogs .o0g ,otg og¡ ,074 t60 300 '600 1 18 t36 4?5 9'5 '?u t90 375 782 ,rlo 203 DIAMETEF OF PAAÏCLES IN MILLIMETERS CTAY TO 9ILI coBBr-€S #4 3/8" 314' 1 tlz' 3" 5'6' 8' 90 80 o?ozôØ60Í t--50fr O 40ffi o_ 30 24 45 0 10 20 I.JJ230 t---t-Ll 40 cÉ f-.250 L¡J(Jr60 LUo- 7Q 80 GRAVEL 61 % LIQUID LIMIT % SAMPLE OF: Sandy Gravel 001 .002 SAND 36 "/o SILT AND CLAY 3 o/o PLASTICITY INDEX O/O FROM: pit I at 7 lz to BTz FeeT CLËAR SOUAFË OPÉNINGSTIME READINGS U,S, STANDARD SERIES 7HR 15 MtN. 6oMtN1gMIN.4 MlN. 1 MIN #200 #100 #ı0 #30 #16 lt&'to0 on 100 20 10 0 .00S .009 .019 .037 .074 ,150 300 600 1'18 2 36 4'75 DIAMETÉFI OF PARTICLËS IN MII-.LIMFTERS eE2.51e.0 37.5 78.2 1t52 203 ---f--- * ......._ - - ct¡Y10 srLT GRAVEL 54 % LIOUIÐ LIMIT o/o SAMPLE OF: Sa Gravelwith Cobble oo88LE3 SAND 41 % SILT AND CI-AY 5 O/O PLASTICIry INDEX % FROM: Pit 10 at 6 to 7 Feet FINE CO,ARSE Figure 11GBADATION TEST RESULTS1 06 0920 TIME READINGS U,S. STANDARO $ERIES #s0 #30 #16 #B CLEAR SOU/\FE OPENINGS 24 HR, 7 HR o 46 MrN. 15 MlN.60MtN19MrN.4 MlN, 1 MlN. #200 #4 3/e 314" 1 112" 3', 5u6" I'100 s0 10 e0 80 70 60 50 40 30 30 Élt!z t--l¡l É, t---z l¿J()El¡¡ o_ 40 ()z tnØ fL t--ztdOv. lÅ,À 50 rì0 7Q 80 90 100 20 t0 .001 .002 .005 .009 .019 .Og7 .o7A .150 .300 .600 1 18 2'36 DIAMETER OF PABTICLES IN MILLIME'TERS 415 9,5 19.0 37,5 76.2 152 20312.5 127 CLAY TO SLT COABLES GNAVEL 68 %SAND 31 %SILTAND CLAY 1 % LIQUID LIMIT o/o PLASTICITY INDEX ?" FROM: Pit 12 at 7 lz la I FeetSAMPLE OF: Sandy Gravel Figure 12GRADATION TEST RESULTS1 06 0920 H EPWORTH-PAWI-AK GEOTÊCH NICAL, INC,TABLE 1SUMMARY OF I.ABORATORY TEST RESULTSJob No. 106 0920Sandy gravelSandy gravelSandy gravelSandy gravelSandy gravelSilty sandSandy gravelGravelly sandSOIL ORBEDROCK T/PEUNCONFINEDCOMPRÊ55WËSTRENGÏHPLAST]CINDEXuqJfDUMTTLIMITS5122,)I4PERCEI{TPASSIT{GNO.200SIEVE4lIJ125336832932SAND(o/o)61546869736615GRADATIONGRAVEL(o/Ð96NATURALDRYDENSITY2.18.9NATURAL}IOISTURECONTENT1Vz-8\Yz -91Vz - BVz6Vz-78-8Yz5-sVz8r/z - 9ZYzDEPTHt?6I0IJ412PTT