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Home My WebLink AboutGeotechnical Engeering Investigation 08.22.2022^ffir%GTLITHOMPSON GEOTECHNICAL ENGI NEERING INVESTIGATION 214 CENTER DRIVE (a.k.a. Parcel 21 85061 000421 GARFIELD COUNTY, COLORADO Prepared for: GLENWOOD PARTNERSHIP, LLLP 214 Center Drive Glenwood Springs, CO 81601 Attention: John Diemoz Floyd Diemoz Project No. GS06693.000-125 August 22,2422 CTllThompson, lnc, Denver, Eort tqlltnc, Colorado SprinS, Glenwood Springs, Pueblo, Sunnmit County - Colorado ghg"tgg, Wy"*ng *'d E"teman, Montama \ ffi TABLE OF CONTENTS scoPE....... SUMMARY OF CONCLUSIONS 5I IE UUNUI IIUN|; PROPOSED CONSTRUCTION ......... SUBSURFACE CONDITIONS.......... EARTHWORK....""..".. ..... 6:r- A--J:--otte r.rlijutng Excavations Subexcavation and Structural Fi||.............. Utility Trench Backflll Foundation Wall Backfii1...............".. FOUNDATIONS.............. Footings on Structural Fill (consisting of on-site clay)................... Footings on Structural Fill (consisting of aggregate base course) SLAB-ON-GRADE FLOORS BELOW-GRAIJE OONSTRUCTION SURFACE DRAINAGE CQNCRETE PAVEi'liENTS................ CONSTRUCTION OBSERVATIONS GEOTECHNICAL RISK LtMtTATTONS ................ FIGURE .1 _ VICINITY MAP Ellll ltrtE o AEDIAt l]LtnTnlrErAFillr I\JL,I \1- a - r1Lt \tnL l_ I t\J I \,r\Jt \rIF I I trlr}t lRtr " - ppnpnstrn ntr\/trt np[/rtrNtT FIGURES 4 AND 5 - SUii/iMARY LOGS OF EXPLORATORY BOR|NGS FIGURES 6 THROUGH 8 _ SWELL-CONSOLIDATION TEST RESULTS TABLE I_ SUMMARY OF LABORATORY TESTING APPEND|X A - PAVEMENT MATFRiAi S AND CONSTRIJCTION RFCOIVIii/iENNATiONS GLENWOOD PARTNERSHIP, LLLP 214 CENTER DR]VE 1 1 2 3 3 4 4 5 5 6 7 7II ..;TLlt' PROJECT NO. GS06693.C00-t25 SCOPE CTllThompson, lnc. (CTLIT) has completed a geotechnical engineering in- vestigation regarding2l4 Center Drive (a.k.a. Parcel 218506100042) in Gadield County, Colorado. We conducted this investigation to evaluate subsurface condi- tions at the site and provide geotechnical engineering recommendations for the proposed development. Our report was prepared from data developed from our field exploration, laboratory testing, engineering analysis, and our experience with similar conditions. This report includes a description of the subsurface conditions encountered in our exploratory borings and provides geotechnical engineering rec- ommendations for design and construction of the proposed development. A sum- mary of our conclusions is below. SUMMARY OF CONCLUSIONS Subsoils encountered in our exploratory borings drilled at the site consisted of approximately 8 inches of sandy clay topsoil over 13 to 33 feet of sandy clay. Silty gravel with scattered cobbles was found below the sandy clay at depths of 14 to 32 feet in seven of our bor- ings. Groundwater was not found in our exploratory borings at the time of drilling. We judge that buildings at the site can be constructed on footing foundations, provided the soils are subexcavated to a depth of 1B inches below bottom of footing elevations. The subexcavated soil should be replaced with densely-compacted, structuralfill. Recom- mendations for subexcavation and structuralfilt are in the report. Ground level floors in the buildings are planned as slabs-on-grade. Building floor slabs should be supported by an 18-inch thickness of densely-compacted, structu ral fill to enhance potential performa nce Additional discussion is in the report. Design pavement section alternatives for the project include 6.5 inches of full-depth asphalt concrete, 4 inches of asphalt concrete GLENWOOD PARTNERSHIP, LLLP 2{4 CENTER DRIVE cTLIT PROJECT NO. GS06693.000-125 1 2 3 4 1 ovei'6 inches of aggregate base course, and 6 inches of Portland ce- ment. Recommendalbns for pavement materials and construction are provided. Slte grading shouH he designed and constructed to rapidly convey surface water off pmrements and away from the buildings. SITE CONDITIONS The property addressed as 214 Center Drive (a.k.a. Parcel 218506100A42) is southeast of the intersection of tlonegan Road and Storm King Road in Garfield County, Colorado. Center Drive, tfte Glenwood Business Center, and the Gten- wood Springs Mall are to the soufrtr- A vicinity map with the location of the site is included as Figure 1. Existing sirgle-family residences and comrnercial buildings are adjacent ts the east property houndary. An aerial photograph of the site is shown on Figure 2. Ground surfae on the property generally slopes down to the south at grades of less than 5 perent. The parcel is predominantly irrigated pas- ture. Numerous irrigaiion ciitch iaterais are preseni on the property. A phoiograph of the site at the time of our subsmface investigation is below. Looking wt from Storm King Road GLENWOOD PARTNERSHIP, LLLP 2I4 CENTER DRIVE cTLIT PROJECT NO. GS06693.000-125 A t PROPOSED CONSTRUCTION CTLIT was provided with a Site Master Plan developed by Glenwood Part- nership, LLLP (dated August 8,2021). A total of nine buildings are planned as shown on Figure 3. The buildings are envisioned as one-story and two-story struc- tures that will be used for combined office and warehouse use. The buildings will likely be steel-framed. Ground-level floors in the buildings are planned as slabs- on-grade. No below-grade areas, such as basements or crawl spaces, will be con- structed. We expect that site grading will involve cut depth and fill thickness of less than 5 feet. We should be provided with civil engineering plans and architectural plans, as they are further developed, so that we can provide geotechnical/geo- structural engineering input. SUBSURFACE CONDITIONS CTLIT investigated subsurface conditions by drilling nine exploratory bor- ings at the site. The borings were drilled on April 21 and 22,2022, with a track- mounted drill rig and solid-stem auger at the approximate locations shown on Fig- ures 2 and 3. Exploratory drilling operations were directed by our engineer, who logged subsurface conditions encountered and obtained representative samples of the soils. Graphic logs of the soils found in our exploratory borings are shown on Figure 4. Subsoils encountered in our exploratory borings consisted of approximately 8 inches of sandy clay topsoil over 13 to 33 feet of sandy clay. Silty gravel with scattered cobbles was found below the sandy clay at depths of 14 to 32 feet in seven of our borings. The maximum depth of our borings was 34 feet. Groundwa- ter was not found in our exploratory borings at the time of drilling. PVC pipe was installed in the borings, prior to backfilling, to facilitate subsequent checks of groundwater. Near-surface groundwater seepage had filled the pipes in four of our GLENWOOD PARTNERSHIP, LLLP 214 CENTER DRIVE 3 cTLIT PROJECT NO. GS06693.000-12s borings to depths of 1 i.5 feet to 25 fbet when they were checkeci on August 15, 2A22. The seepage may be due to flood irrigation, which commenced after drilling Samples of the soils obtained from our exploratory borings were returned to our laboratory for pertinent testing. Firre samples selected for one-dirnensional, swell-consolidation testing exhibited volume change ranging from 0.4 percent swell to 0.1 percent consolidation when wetted under a load of 1,000 psf. Engi- neering index testing on three samples of the soils indicated liquid limits of 30 to 33, piasticity indices of 13 to i6 percent, and 66 to 82 percent silt and clay (pass- ing No. 200 sieve). Two samples of the soil tested contained 0.00 percent water- soluble sulfates. Swell-consolidation tests results are shown on Figures 6 through B. Laboratory testing is summarized on Table l. EARTHWORK We expect that site grading will involve cut depth and fill thickness of less than 5 feet. Excavation depths to construct the building foundations are expected to be less than 4 feet below ground surface after site grading is completed. Site Gradins Areas that wiii receive fili should be strippecl of vegetation ancj organic soils Stripping depths of 6 to 12 inches should be expected across most of the site. lrri- gaticn ditch iaterals that wiii be abancionecj shouid be graciecl and filied to ensui'e that seepage flow does not occur. Altel striS.rpirrg is accomplished, the resulting ground surface in areas that will receive fill should be scarified to a depth of at least 6 inehes, moisture-treated, and compacted. Soft areas should be reworked or otherwise stabilized prior to placing fill, The on-site soils are suitable for reuse as overlot fill, provided rocks GLENWOOD PARTNERSHIP, LLLP 2I4 CENTER DRIVE cTLIT PROJECT NO. Gsn66e3_000-.r25 t1 larger than 6 inches in diameter, organics, and debris are removed. Grading fill should be placed in maximum 10-inch thick lifts, moisture-conditioned to within 2 percent of optimum moisture content, and compacted to at least 95 percent of standard Proctor (ASTM D 698) maximum dry density. Placement and compaction of fill should be observed and tested by CTLIT during construction. Excavations Our subsufface investigation indicates that excavations at the site can be accomplished with conventional, heavy-duty excavation equipment. The natural clay soil at the site will likely classify as Type B based on OSHA standards govern* ing excavations. Temporary slopes deeper than 5 feet and above groundwater should be no steeper than 1 to 1 (horizontal to vertical) in Type B soils. Contrac- tors are responsible for site safety and providing and maintaining safe and stable excavations. Contractors should identify the soils encountered in excavations and ensure that OSHA standards are met. We do not expect that excavations for the proposed construction (less than 4 feet deep) will penetrate the free groundwater table. Excavations should be sloped to gravity discharges or to temporary sumps where water from precipitation can be removed by pumping. Subexcavation a nd Structural Fill Our subsurface information indicates the undisturbed, natural clay soil has potential for volume change ranging from low swell to low consolidation when wet- ted. We judge that buildings at the site can be constructed on footing foundations, provided the soils are subexcavated to a depth of at least 18 inches below bottom of footing elevations. Building floor slabs should be supported by an 18-inch thick- ness of densely-compacted, structural fill to enhance potential performance. GLENWOOD PARTNERSHIP, LLLP 214 CENTER DRIVE 5 cTLIT PROJECT NO. GS06693.000-125 The subexcavated soiis should be replaced with densely-compacted, struc- tural fill. The on-site soils can be used as structuralfill, provided they are free of rocks larger than 3 inches, organics, and debris. A positive alternative would be to import a CDOT aggregate base course or similar soil for use as structural fill. This would result in higher bearing capacities for footings and enhanced performance of footings and floor slabs. Structural fill should be placed in loose lifts of B inches thick or less, mois- ture-conditioned to within 2 percent of optimum moisture content, and compacted to at least 98 percent of standard Proetor (ASTM D 693) maximum dry density. Moisture content and density of structural fill should be checked by CTLIT during placement. Observation of the compaction procedure is necessary. Utilitv Trench Backfill IJnderoround Irfilifies for fhc nrnicnf rarill likelrr ha nnnqfrrrnJed hclnrnr aroac, nfgr'--" 'vr iliv pavements and exterior concrete flatwork. Compaction of treneh backfill will have a significant effect on the life and serviceability of these structures. lmproper com- paction of trench backfill can cause backfill materials to consolidate leading to po- tentially severe deformation of pavements and damage to concrete slabs. The on- site soils free of rocks larger than 4 inches in diameter, organics, and debris can be used as utility trench backfiil. Trench backfill should be placed in loose lifts of 10 inches thick or less, m.^,ic*:rro-r-^.n,4ifi.-.na,-l *,-. rrri4L-ir. C ;ra*n.-.-.* .-.# *a4iar,* *^ia*,rr* rn*$a*4 *n.-l ax-irrvlJrvrv evlrvrrlvrlvv rv vvrtrlill4 PE;twgttL \-rt \ryL[ttLillt ttt\rto[Lrtg \,vtltgll( clllv rJ\,tll- pacted to at least 95 percent of standard Proctcr (ASTM D698) maximum dry den- cifrr -Qnanial nara ic naarlarl {nr hanlzfill al.liananl *n manhnlac anA rrarlinal rioareitrr vlrvv.qr vk.v rs.rgvvvu lvr vgvl\rrrr gUJqvgtll tv lllqlltlvlVJ qliV VVr(lvql llggt pipes. Placenrent atrct cotrtpacliolr of backfill should be observerl arrcl Lested by our firm during construction. GLENWOOD PARTNERSHIP, LLLP 214 CENTER DRIVE eTtlT PROJEeT N0. cS06693.000-125 fI Foundation Wall Backfill Proper placement and compaction of foundation wall backfill is important to reduce infiltration of surface water and settlement from consolidation of the backfill soils. The soils excavated from the site can be used as backfill, provided they are free of rocks larger than 4-inches in diameter, organics, and debris. Backfill should be placed in loose lifts of approximately 10 inches thick or less, moisture-conditioned to within 2 percent of optimum moisture content, and compacted to at least 95 percent of standard Proctor (ASTM D 698) maximum dry density. Our representative should test moisture content and density of the backfill during placement. FOUNDATIONS Our subsurface information indicates the natural clay soil has potentialfor volume change ranging from low swell to low consolidation when wetted. We judge that the buildings at the site can be constructed on footing foundations, pro- vided the soils are subexcavated to a depth of at least 18 inches below bottom of footing elevations. The subexcavated soil should be replaced with densely-com- pacted, structural fill. The structural fill should be in accordance with recommenda- tions in the Su vation and Structural F section. Structural fill consisting of imported aggregate base course would allow footings with higher bearing pres- sures, as compared to structural fill consisting of the on-site clay soil. Recommended design and construction criteria for footings are below. These criteria were developed based on our analysis of field and laboratory data, as well as our engineering experience. GLENWOOD PARTNERSHIP, LLLP 214 CENTER DRIVE crLlT PROJECT NO. GS06693.000-12s 7 Footings on Structural Fill iconsistins of on-site elavl Footings suppofied on an 1B-inch thickness of densely-ompacted, structural fill consisting of the on-site clay can be designed for a max- imum net allowable soil bear:ing pressure of 2,000 psf. The weight of backfill above the footings can be neglected for bearing capacity cal- culations. The structural fill should be in accordance wilh recommen- dations in the Subexc_avafip-_nffi section- A friction factor of 0.35 can be used to calculate resistane to sliding between the concrete footings and structural fill consistiirqg of the on- site clay soil. Continuous wall footings should have a minimum widttr of at least 20 inches. Foundations for isolated columns should have nninimum di- mensions of 30 inches by 30 inches. Larger sizes may he required, depending upon foundation loads. Grade beams and foundation walls should be well-reinforoed. We recommend reinforcement sufficient to span an unsupported dis- tance of at least 12 teet. The soils under exterior footings should be protected fiqn freezing. We recommend the bottom of footings be constructed at teast 36 inches below finished exterior grades. The Garfield County building department should be consulted regarding frost protedbn require- ments. Footings supported on an 18-inch thickness of densely-compacted, structural fill consisting of imported aggregate base cource can be designed for a maximum net allowable soil bearing pressure of 3,000 psf. The weight of backfill above the footings can be nqflected for bearing capacity calculations. The structuralfill should be in accord- ance with recommendations in the Subexcavation and Stuilctural Fill section. A friction factor of 0.40 can be used to calculate resistane to sliding befueen the concrete footings and structural fill consislfmg of im- ported aggregate base course. GIENWOOD PARTNERSHIP, LLLP ZI4CENTER DRIVE 1 2 3 4 5. Footings on Structur?l Fill {consisting of aqqregate base coursel 1 2 o(, GILIT PROJECT NO. GS06593.000-125 3.Continuous wallfootings should have a minimum width of at least 16 inches. Foundations for isolated columns should have minimum di- mensions of 24 inches by 24 inches. Larger sizes may be required, depending upon foundation loads. Grade beams and foundation walls should be well-reinforced. We recommend reinforcement sufficient to span an unsupported dis- tance of at least 12feet. The soils under exterior footings should be protected from freezing. We recommend the bottom of footings be constructed at least 36 inches below finished exterior grades. The Garfield County building department should be consulted regarding frost protection require- ments. SLAB-ON-GRADE FLOORS Ground level floors in the buildings are planned as slabs-on-grade. The nat- ural clay soil at the site has potentialfor volume change ranging from low swellto low corrsolidation when wetted. Building floor slabs should be supported by an 18- inch thickness of densely-compacted, structural fill to enhance potential perfor- mance. The structural fill should be in accordance with recommendations in the Su and Structural Fi il section. Structural fill consisting of imported ag- gregate base course would enhance potential slab performance, as compared to structural fill consisting of the on-site clay soil. Based on our analysis of field and laboratory data, as well as our engineer- ing experience, we recommend the following precautions for slab-on-grade con- struction at this site. Slabs should be separated from wall footings and column pads with slip joints, which allow free veftical movement of the slabs. Underslab plumbing should be pressure tested for leaks before the slabs are constructed. Plumbing and utilities which pass through GLENWOOD PARTNERSHIP, LLLP 2,'4 CENTER DRIVE cTLlr pRoJECT NO. GS06693.000-125 4 5 1 2 I slabs shouid be isolateci from the slabs with sieeves anci provideci with flexible couplings to slab supported appliances. Exterior concrete flatwork should be isolated from the buildings. These slabs should be well-reinforced to funciion as independent units. Frequent controljoints should be provided, in accordance with Amer- ican Concrete lnstitute (ACl) recommendations, to reduce problems associated with shrinkage and curling. The lnternational Building Code (lBC) may require a vapor retarder be placed between the subgrade soils and concrete slab-on-grade floors. The merits of installation of a vapor retarder below floor slabs depend on the sensitivity of floor coverings and building to moisture. A properly installed vaper retarder (10 mil minimum) is more benefi- cial beiow concrete siab-on-grade floor"s t^",here fioor coverings will be sensitive to moisture. BELOW.GRADE CONSTRUCTION We understand the buildings will not be constructed with below-grade ar- eas, such as basements or crawl spaces. lf construction plans evolve to include below-grade areas, we should be informed so that we can provide recommenda- tions for lateral earth pressures and subsurface drainage systems. SURFACE DRAIN,IGE Surface drainage is criticai to the peifo;-mance of founciations, fiooi"siabs, and concrete flatwork. Site grading should be designed and constructed to r"apidly convey surface water away fr"om the buildings. Prcper suface drainage and irriga- tion praetiees can help colrtrol the atnourrl of sulface waler [lra[ perretlates tc'foun- dation levels and contributes to settlement or heave of soils that support founda- tions and slabs-on-grade. Positive drainage away from the foundation and avoid- GLENWOOD FARTNERSI.IIP, LLLP 2I4 CENTER DRIVE 3 4 5 cTLIT PROJECT NO. cS0669-?.000-12s tv ance of irrigation near the foundation also help to avoid excessive wetting of back- fill soils, which can lead to increased backfill settlement and possibly to higher lat- eral earth pressures, due to increased weight and reduced strength of the backfill. We recommend the following precautions. The ground surface surrounding the exterior of the buildings should be sloped to drain away from the buildings in all directions. We rec- ommend a minimum constructed slope of at least 12 inches in the first 10 feet (10 percent) in landscaped areas around the buildings. Backfill around the foundation walls should be moisture-treated and comoacted oursuant to recommendations in the Foundation Wall - - - - -l Backfill section. The buildings should be provided with roof drains or gutters and downspouts. Roof downspouts and drains should discharge well be- yond the limits of all backfill. Splash blocks andlor extensions should be provided at all downspouts so water discharges onto the ground beyond backfill zones. Landscaping should be carefully designed and maintained to mini- mize irrigation. Plants placed close to foundation walls should be lim- ited to those with low moisture requirements. Sprinklers should not discharge within 5 feet of foundations. Plastic sheeting should not be placed beneath landscaped areas adjacent to foundation walls or grade beams. Geotextile fabric will inhibit weed growth yet still allow natural evaporation to occur. CONCRETE Concrete in contact with soil can be subject to sulfate attack. We measured water-soluble sulfate concentrations of 0.00 percent in two samples of the soil from the site (see Table l). For this level of sulfate concentration, ACI 318-08, "Code Requirements for Structural Concrete", indicates there are no special ce- ment requirements for sulfate resistance in concrete that is in contact with the sub- soils. GLENWOOD PARTNERSHIP, LLLP 214 CENTER DRIVE cTLIT PROJECT NO. GS06693.000-125 1 2 3 4 11 ln our experience, superficiai damage mayoocur to the exposeci surfaces of highly permeable concrete. To control this risk and to resist treeze thaw deteriora- tion, the water-to-cementitious materials ratio shouH not exceed 0.50 for concrete in contact with soils that are likely to stay moist due to surface drainage or high- water tables. Concrete should have a total air content of 6% +l-1.5%. PAVEMENTS Based on the AASHTO Classification systenn, we estimate the naturai soils and densely-compacted, site grading fill construcfied with the on-site soils will clas- sify as AASHTO Group 4-6. We estimate a resilient modulus (Mn) of 5,000 psi based on our experience with similar soils. Traffic loading numbers were not available atthis writing. We assume pave- menfs will he nrimarilrr cr rhicnf fn ar rfnrnnhila fraffin Snrna haarnr frr rnk fraffin er rnhsrrtv, svvtt as garbage trucks, may occur in some areas. We estimated an Equivalent Single Axle Load (ESAL) value of 200,000 for the pavernents. We should be provided with design traffic numbers when available so thatwe can review and/or refine our recommendations. Our recommend minimum pavernent section alternatives are shown in Table 1 below. Table 1 Recommended Pavement Sedbn Alternatives urrtilglt I tHlilu- Loading (ESAL) --l--lt ^^-^--a^AslJilart tl.,()llulere (Ac) a -.^L -k F^.^ --,^^Asphan Gonercie + Aggrqate Base Course (AG + ABCi h -..-rl-....--,t R----rontano uemenr Concrete (PCC) 200 000 6.5',AC 4.0'AC + 9.0" ABC 6.0' PCC GLENWOOD PARTNERgHIP, -LLLP214 CENTER DRIVE cTl lT pPa lFeT N.l Gcnaao? nnn-{rr 12 Pavement performance can be problematic in areas wtnere heavy trucks turn and stop, such as entrances and dumpster pads. ln areas subject to traffic by heavy trucks, we recommend the client consider Portland oerrent concrete pave- ment that is at least 6 inches thick. The per{ormance of a pavement system depends on tfrc quality of the pav- ing materials and construction, as well as the support characfteristics of the sub- grade soils. lf the pavement system is constructed of inferior nnaterial, then the life and serviceability of the pavement will be substantially redud- We have included material and construction recommendations for flexible and rigilrl pavements in the attached Appendix A. A primary cause of early pavement deterioration is w#infiltration into the pavement system. The addition of moisture usually results in softening of the sub- grade soils and eventual failure of the pavement. We recomrnend drainage be de- signed for rapid removal of surface runoff from pavement surhaes. Final grading should be carefully controlled so that design cross-slope is malintained and low spots in the subgrade which could trap water are eliminated- Portland cement con- crete drainage pans should be considered in areas where water will be flowing across pavement surfaces. CONSTRUCTION OBSERVATIONS We recommend that CTL Thompson, lnc. be retained to provide construc- tion observation and materials testing services for the project" This would allow us the opportunity to verify whether soil conditions are consistentwith those found during this investigation. lf others perform these observations" frtey must accept responsibility to judge whether the recommendations in this tryort remain appro- priate. lt is also beneficialto projects, from economic and pradkal standpoints, GLENWOOD PARTNERSHIP, LLLP 214 CENTER DRIVE GTLIT PROJECT NO. GS06693.000-125 13 when there is continuity hetween engineering consultation and the construction observation and matedah testing phases. GEOTECHNICAL RISK The concept of dsk is an important aspect of any geotechnical evaluation. The primary reason for{his is that the analytical methods used to develop ge- otechnical recommendalbns do not comprise an exact science. We never have complete knowledge of sbsurface conditions. Our analysis must be tempered with engineering judgmmrt and experience. Therefore, the recommendations in any geotechnical evaluatbn should not be considered risk-free and are not a guar- antee that the interac-tinnr between the soils and the proposed structure will lead to performance as desired or intended. Our recommendations in the preceding sec- tions constitute our eslfrmate of those measures that are necessary to help the buildings perform satisfadorily. lt is criticalthat all recommendations in this report are fgllowed. This report has been prepared for the exclusive use of the client. The infor- mation, conclusions, and recommendations presented herein are based upon con- sideration of many fafuns including, but not limited to, the type of structures pro- posed, the geologic seilitqg, and the subsurface conditions encountered. The con- ciusions and recommernclations contained in the report are not valid for use by oth- ers. Standards of pradir= eontinuously ehange in geotechnieai engineering. The recommendations prov&ded in this report are appropriate for about three years. lf the proposed project !s rrot constructed within three yeai's, i,,e should be ccntacted to determine if we shouH update this report. GLENWOOD PARTNERSHIP, LLIJ 2I4 CENTER DRIVE CTLIT PROJECT NO. GS06693.00G|U6 tl^ LIMITATIONS Our exploratory borings provide a reasonable charac{erization of subsur- face conditions at the site. Variations in the subsurface corditions not indicated by borings will occur. We should be provided with civil engirreering and architectural plans, as they are further developed, so that we can provitfu geotechnical/geo- structural engineering input. This investigation was conducted in a manner consbtent with that level of care and skill ordinarily exercised by geotechnical engineels currently practicing under similar conditions in the locality of this project. No warranty, express or im- plied, is made. lf we can be of further service in discussir4g the contents of this re- port, please call. CTLITH P Revbwed by: Mechling, P.E.D. Kellogg nior Principle Engineer Manager ti GLENWOOD PARTNERSHIP, LLLP 214 CENTER DRIVE o I oSezgs cTLIT PROJECT NO, G506693.000-l2s {5 ffi 0 J00 @ NOTE: SCALE: l'* 8d GLENWOffi trHTNERSH|P, t-Lr-Ptr4ctNTEnffi SATELLITE IMAGE FROM MAXAR (coevRrcHr zozl) Vicinity MapPROJECT NO. GSO6693,OOO-1 25 Flg. 1 I@ I 0stooEr?E!!!!= EGEND: TH_1 APPROXIMATE LOCATION OF . EXPLORATORY BORING - APPROXIMATE LOCATION OF PROPER1Y BOUNDARY CTEI SATELLfTE IMAGE FROM MAXAR (CoPYRTGHT 2022) GLE}.IWOOD PAFTNEN€HP,LW PrcJet No. GSO669II.OOO-125 tr nt Aerial Photograph ric. 2 { oD6G ffi 1f-d .GEND: TH-1 ,l{m{X{tfltrfiE LOCATbN OF . ESMUIRf,IIRf, BOR TG 0TE: ffi0mmlihlc BY GiTNUOOD (0NEEJUILY 27,2022) qls$i@@e FTNESlf,rIlF FrqENb. GSOA6qS.{nO-1 2s tr tillrItliil !l ! hut I GARFIEIID OUIIINIIY 'ffi- D.NEGAN R.AD 6 I g =Y + -:]l- o t rl-l vEr!rcR DRTVE ?---l-t--Fv ._ ---t- --'l.-+cb--{- --FE TH-4N o TH-1 f@tLil--t-tt-il-G !t Proposed Development Flc. 3 TH-1 El: 5,726 10t12 GLENWOOD PARTNERSHIP, LLLP TH.2 El:5,724 TH-3 @5,722 TH.4 El:5,728 TH.4N TH.4S El:5,723 TH-5 El:5,734 TH€ El: 5,736 trllltliT El:5760 11t12 1112 s g l0 20 I il12 16r12 v SUMMARY LOGS OF EXPLORATORY BORINGS214 CENTER DRIVE PROJECT NO. GS06693.000-125 FIG. 4 ffi LEGEND: TOPSOIL, CI.AY, SANDY, MOIST, BROWN. L] crav, sANDy, MEDrurM srFF To vERy srFF. nfio*r, BRowN. (cL)U Fl c*o-l, srtry, '.ATTERED coBBBLEs, MEDrrru!ffi{sE To DEN*E, Morsr, BR-owN. (cM) VA DRIVE SAMPLE. THE SYMBOL 7/12 INDICATES 7HtCIWS OF A 14o-POUND HAMMER FALLING 30 INCHES WERE REQUIRED TO DRIVE A 2.5-IT{CIfiI(}.D. CALIFORNIA.BARREL SAMPLER 12 INCHES.F T PRACTICAL AUGER REFUSAL g INDICATES LEVEL TO WHICH NEAR-SURFACE GSKUIIIIIDWATER SEEPAGE HAD FILLED PIPE WHEN CHECKED ON AUGUST 15. 'K@,.-frHIS SEEPAGE OCCURRED AFTER FLOOD IRRIGATION COMMENCED AT TFE6fIIE. NOTES: 1. EXPLORATORY BOR|NGS WERE DR|LLED ON APfrIILZfl AND 22. 2022 WiTH A TRACK.MOUNTED RILL RIG AND 4-INCH DIAMETER,S(LID.STEM AUGER. ?. GROUNDWATER WAS NOT FOUND IN OUR BORNIWAT THE TIME OF DRILLING. PVC PIPE WAS INSTALLED IN OUR BORINGS TO FACILITATESIItsSEQUENT CHECKS OF GROUNDWATER. 3. THESE LOGS ARE SUBJECT TO THE EXPLANATIOINS$,, I.IMITATIONS, AND CONCLUSIONS IN THIS REPORT. SUMMARY LEGEND OF EXPLORATORY BORINGS nt Ef,llimnnDADTf,tEbCUtD l I l b 214 CENTER DRIVE PROJECT NC. GS066e3.000-125 F!G. 5 ffi z,(!o 6z{-ro-x!fs74oo0Et G-Jo-Eo(,4, t 2 -[ 1 @ o.1 APPLIED PRESSURE. KSF 1.0 DRY UNITWEIGFTIT= MOISTURE CONIIEINIII= DRY UNITWEIG}IIII= MOISTURE CONIIENIII= 10 100 110 PCF 16.8 % 10 114 15.2 Swell-Colsolidation Test Resulls Fio 6 $cnrnple of CLAY, SANDY (CL) Frorn Frorn TH-1 AT 9 FEET 3 2 zo0z-t &xW2 #zo 6ou!t.o- -4 =o(, '6 0.1 APPLIED PRESSURE. KSF 100 PCF % $onnple of CLAY, SANDY (CL) TH-4 AT 9 FEET GI..EIW'OD PARTNERSHIP, LLLP 2l,tCEilTER DRM PROJECT NO. GS06693.000-1 20 /{ EXPANSION U N DER OOIITISTANT PRESSU RE DU E TO ld$OE-ilTINGI r r r r I it : I I I I 7 \ ) , EXPANSION UNDERCONSTANT PRESSU RE DU E TO V{fETTING \Fi\ \ t 1.0 ffi 0 -z zofiaz o. q -o4 o @aul -3 o- =oO-5 0.1 APPLIED PRESSURE. KSF 1'.10 10 DRY UNITWEIGHT= MOISTURE CONTENT= 10 DRY UNITWEIGHT= MOISTURE CONTENT= 100 108 PCF 13.2 100 103 PeF lllz "t Somple of CLAY, SANDY {CL) From From TH-4N AT 14 FEET ? 2 zou6zq O- -ix IU s 26't6o lrJM-t Eo -4 0.1 APP!-IED PRESSURE. KSF Somple of cLAy, sANDy (eL) TH-4S AT 4 FEET GLENWOOD PARTNERSHIP, LLLP,4' NFNTtrP NtrIVF PROJECT NO. GS06693.000-1 20 Swell-Consolidation Test Results Fiq. 7 J-- EXPANSION UNDER CONSTANT PRESSI.,IRE DUE TO WETTINGrlllr l l lilt 'l I \ I . EXPANSION UNDER CONSTANT PRESSURE DUE TO WETTING i I F i--\, \ -I \ ) 11.{D ffi 7 o ( 4 3 2 0 -2 -3 Z-do6z O- -sx- IU s S.o0o UJt --ro- Eoo -8 0.1 APPLIED PRESSURE . KSF Somple of CLAY, SANDY (cL) .!0 ffiY UNITWEIGHT= IMfiCISTURE CONTENT= 121 12.3 100 PCF YoFromTH.6 AT 9 FEET GLENWOOD PARTNERSHIP, LLLP 214 CENTER DRIVE PROJECT NO. GS06693.000-1 20 Swell-Consolidation Test Results Fig. 8 \\-- ADDITION|AL COMPRESSION UNDER CONSTAINIT PRESSURE DUE TO -wETTll'sGItil it it il l |lllF \ \ ) 1.0 1ABLE I SUMMARY OF I.ABORATORY TESTING PROJECT NO. GS06693.000-120 ffi DFSCRIPTION ELAY. SANDY (EL) CLAY. SANDY (CL) CLAY, SANDY (CL) CLAY. SANDY (CL) GLAY, SAND'/ (CL) CLAY. SANDY (CL) CLAY. SANDY (CL) CLAY. SANDY (CL) CLAY. SANDY (CL) CLAY. SANDY (CL) CLAY. SANDY (CL) CLAY. SANDY (CL) CLAY. SANDY (CL) CLAY, SANDY (CL) CLAY, SANDY (CL) CLAY. SANDY (CL) CLAY. SANDY (CL) CLAY. SANDY (CL) PASSNNG NO.200 SIEVE (rys\ T7 82 66 WATER SOLUBLE SULFATES (%\ 0.00 0.00 UNCONFINED COMPRESSION (PSF) 4,700 16.100 7,600 *SWELL fo/Al 0.1 0.4 c'r.4 1.1 -0.1 ATTERBERG LIMITS PLASTICITY INDEX (ola) 16 13 14 I.IQUID LIMIT (a/a\ JJ 30 31 DRY DENSiIT'Y (PCF) 11tl 111 107 107 100 113 124 105 1 1:l 116 113 130 108 119 12'l 1 1t5 11,t 109 MOISTURE CONTHNT (0a) 14.'l 1AE 1S;l 20.5 25.1 12_3 11.5 2e.li 16.6 15-12" 13.?_ 153 11_',t 10.3 1Z:\ 16.5 15.7 19-,{ DEPTH fFEET) 4 s 4 14 24 4 o 19 4 I 14 19 4 4 I 4 I 14 HXPLORATORY BORING TH.1 TH.1 'fH-2 't'H-2 TH.2 TH-3 TH-3 TH-3 TH4 TH-4 TH-4N TH.4N TH.4S TH-6 TH-6 TH-7 TH:7 TH-7 * SWEtt MEASURED UNDER 1,OOA PSF APPTIEP PRESSURE, NHGATIVE VALUH INDICATES EONSOLIDATION.Fege 1 of 1 ffi APPEIIIDIX A PAVEMENT CONSTRUCTION AND MATERIALS RECOMMENDATIONS GLENWOOD PARTNERSHIP, LLLP 214 CENTER DR]VE CTLIT PROJECT NO. GS06693.000-125 ffi PAVEMENT MATERIALS Material properties and construction criteria for the pavement alternatives are provided below. These criteria were developed from analysis of thefreH and ffioratory data and our experience. lf the materials cannot meet these remm- npendations, then the pavement design should be reevaluated based upon avail- *ke materials. Materials planned for construction should be submitted and the applicable laboratory tests performed to verify compliance with the specifications. Asphalt Concrete (AC) AC should be composed of a mixture of aggregate, filler, hydrated lime and asphalt cement. Some mixes may require polynrermodi- fied asphalt cement, oi'make use of up to 25 percent recla*med as- phalt pavement (RAP)A iob mix desiqn is recommended and peri- odic checks on the iob site should be made to verifu compfrance with specifications. 2.AC should be relatively impermeable to moisture and shourH be de- signed with crushed aggregates that have a minimum of 80 percent of the aggregate retained on the No. 4 sieve with two mecfnanically fractured faces. Gradations that approach the maximum density line (within 5 per- cent between the No. 4 and 50 sieve) should be avoided. Agrada- tion with a nominal maximum size of 1 or 2 inches developed on the fine side of the maximum density line should be used" Totalvoid content, voids in the mineral aggregate (VMA) arnd voids filled should be considered in the selection of the optimunm mphalt cement content. The optimum asphalt content should be sebcted at a total air void content of approximately 4 percent. The nnixture shouici have a minimum VMA of 14 percent and between ffi per- cent and 80 percent of voids filled. Asphalt cement should meet the requirements of the Superpave Perfbrmance Graded (PG) Binders. The minimum performhg as- phalt cement should be PG 58-28. Hycirated lime should be acided at the rate of 1 percent by dry weight of the aggregate and should be included in the amofffi passing the No. 200 sieve. Hydrated lime for aggregate prefreat- ment should conform to the requirements of ASTM C 2A7,Type N. 1 3. 4 5. 6. GIEffOOD PARTNERSHIP, LLLP zlI4CEI{TER DRIVE cnulT FRoJECT NO. cs066s3.000-1 *25 A' ffi Paving strouH only be performed when subgrade temperatures are above 4ffF and air temperature is at least 40oF and rising. HMA shoulH not be placed at a temperature lower than 245oF for mixes conhining PG 58-28 asphalt, and 290oF for mixes containing polymer rmdified asphalt. The breakdown compaction should be completed hefore the mixture temperature drops 20oF. The maxinmrn compacted lift should be 3.0 inches and joints should be Saggered. No joints should be placed within wheel paths. 10 HMA should be compacted to 94 + 2 percent of Maximum Theoreti- cal Densi$r- The surface shall be sealed with a finish roller prior to the mix mofrng to 185oF. '11 Placement and compaction of HMA should be observed and tested by a representative of our firm. Placement should not commence until the srftgrade is properly prepared (or stabilized), tested and proof-rolled.. Proof rolling should be performed with the heaviest machine alrailable at the time. The proof roller should be selected from macfnlnes providing both mass and high contact pressure. Asgregate Base Course (ABC) A Class 6 Cobrado Department of Transportation (CDOT) specified aggregate base course should be used. A recycled concrete alterna- tive which me# the Class 6 designation is also acceptable. Aggregate base course should have a minimum Hveem stabilometer value of 78. Aggregate base course or recycled concrete material must be moisture sffile. The change in R-value from 300 psi to 100 psi exu- dation pressuile should be 12 points or less. Aggregate bre course or recycled concrete should be laid in thin lifts not to exceed I inches, moisture treated to within 2 percent of optimum moisture contemt, and compacted to at least 95 percent of maximum modified Prodor dry density (ASTM D 1557, AASHTO T 1 B0). Placement arxd compaction of aggregate base course or recycled con- crete should be observed and tested by a representative of our firm. Placement shoruH not commence until the underlying subgrade is properly prepared and tested. 7. 8. o 1 2 3 4 GLENWOOD PARTNERSHIP, LLLP 214 CENTER DRIVE CTLIT PROJECT NO, GS06693.0OO-|6 A-2 ffi Portland Cement Co rete Pavement {PCCP) Podland cement concrete should have a minimum compressive strength of 4,500 psi at 28 days and a minimum modulus of rupture (flexural strength) of 650 psi. A CDOT approved Class P mix design is also accepiabie. A iob mix deSiqh iS re0ommeniJed anei perioetic should be made to specifications. Normal Type I or Type ll cement may be used in concrete at this site. Portland cement concrete should not be placed when the subgrade oi= aii=temperature is below 40oF. Free water shouid not be finished into the conerete surfaee and fin- ishers should not use a steeltrowel on the surface. Atomizing noz- zle pressure sprayers for applying finishing compounds are !'ecom- mended whenever the concrete surface becomes difficult to finish. Curing of the portland cement concrete should be accomplished by the use of a curing compound. The curing compound should be ap- n|iprl in annnrdanna rnrifh rrranr rfanfr rrar rar.rrrrrrnandafinnqr..-_ Curing procedures should be implemented, as necessary, to pro- tect the pavement against moisture loss, rapid temperature change, freezing, and mechanical injury. Construction joints, including longitudinal joints and transverse .joints, should be formed during construction or sawed after the con- crete has begun to set, but prior to uncontrolled cracking. Alljoints should be properly sealed using a rod baek-up and ap- proved sealant. Traffic should not be allowed on the pavement until it has properly cured atrd aclrieved at least 80 percent of the desigrr strengtlr, wittr saw joints already cut. 10,Placement of poftland cement concrete should be observed and tested by a representative of our firrn. Placement should not corn- mence untilthe subgrade is properly prepared and tested. 1 GLENWOOD PARTNERSHIP, LLLP 214 CENTER DRIVE 2 3 A+ 5 o 7 8 I ^tt tT DDn tE-T ltn A-J ffi Surfare water from precipitation and landscape irrigation is likely to infiltrate backfill placed adjaoenfi to site earth retaining walls. This water can cause reduced backfill strength anrd result in 5y6roefiatic pressures on the retaining walls. Drains should be constructed behind ffie bases of the footings for the walls. CTL|Thompson. lnc. Denver, FortGollins, Colorado Sprinqs, Glenwood Sprinqs, Pueblo, Summit Countv - Colora:do Cheyenne, Wyoming and Bozeman, Montana GTL ITHOMP$CDN November 7,2$23 Andover Mamryement GrouP 333 East Maiiirn Street, Suite 300 Louisville, K( 44242 Attention: Dan Kunau Subject: GeotechnicalEngineeringlnvestigation-Addendum 214 Center Drive (a.k.a. Parcel 21 85061 00042) Garfield CountY, Colorado CTLIT Project No. GS06693'001-125 CTlIT[1ornpson, lnc. (CTLIT) performed a geotechnical engineering investigation regard- ing214 CenterDrive (a.k.a. Parcel 218506100042)in Garfield County, Colorado. Subsequentto oul report, we\rere asked to prepare this addendum. This letter provides geotechnical engtr neering recdrrunendations and design criteria for earth retaining walls, seismic design, and belled pier forundations, Site Earth ina Walls We urderstand site earth retaining walls are included in the current plans for the proilect. Earth retainirq walls must be designed to resist lateral earth pressures. Many factors affecf ilhe values of therebn lateral earth pressure. These.factors include, but are not limited to, the type, compadilon, slope, and drainage of the backfill, and the rigidity of the wall against rotatiilon and deflectiom For a very rigid wall where negligible or very little deflection will occur, an "at-resf lderal earth pressure sfrouJO be used in design. For walls that can deflect or rotate 0.5 to 1 percent of wall height (dryending upon the backfilltypes), design for a lower "active" lateral earth pressure may be appropiate. For 5gdlditl soils conforming with recommendations in the Foundation Wall Backfil!sec- tion of our repont that are not saturated, we recommend design equivalent fluid densities of d least 45 pcf a{16 60 pcf for the "active" and "at-rest" conditions, respectively. Passive earth ples- sure calculated ryith an equivalent fluid pressure of 300 pcf is appropriate for this site, provfreied backfill in frorffi of the retaining wall footings will not be removed during the lifespan of the shua- tures. ffi The earth reiainlng walldrains can consEstof 4-ineh diameter, sioited, PVC pipe en- cased in free-draining gravel. A prefabricated dn$rmge composite should be placed adjacent to the backs of the walls. Care should be taken durirq backfill operations to prevent damage to drainage composites. The drains should discharge via gravity outlets or weep holes. 9.R!Fmic Desiqn Pararneters We expect the proposed buildings will be oonsidered Risk Category ll, pursuant to the 2021 lBC. The soil and bedrock are not expeetedfio respond unusually to seismic activity, and they have low susceptibility to liquefaction. Pursuan#to the ASCE/SEI 7-22 and our subsurface information, we judge that Site Soil Class D is appnopriate for seismic design. ln our opinion, the developer should consider retaining a geophysicdlmnsultant to assist with evaluation of the seismic site soil classiiication of the site. We consftder the seismic criteria on the tabie below to be appropriate for use in structural design at the silb- Table I Flallad Fiarc: We understand that the client anticipates ffi two of the one-story, metal buildings nlanned for fhe -eil+ ."vi!! 1.,+ rr rhiant fa eianifinanf rwrJlfift fnr:rac Thc nlianf dacirae hallad ni=r f.^.r rn- t,rvr iver I dations for these buildings to resist the uplift. Oursr$surface information indicates that the soils below the siie are generally sandy elay soil that b nnedium stiff to very stiff with some very soft zones. Gravel and cobble soil is below the sandy dhy, but the elevation is not consistent. The gravel/cobbles are deeper than 30 feet at some localions. Design and construction criteria for belled piers are below. Relled oiefs should he rJesioner{ fnr a mavimr rm allnurahla anr{ haarinn hroecr rrgll lv l,l vvvvi of 3.000 psf. Skin friction should be nneglected. ANDOVER MANAGEMENT GROUP 214 CENTER DRIVE FTt tT Oblr lEl\f f,rn EcAeAdr AnA 4 4EvrLlr r r rtvrvvvevsr.vvt-t4J 1 q^0.32 Sr 0.057 Sos 4.24 Sor 0.083 S."o 0.36 Snttr 0,13 Tr 4 PGAnn o.2 Vs:o 260 Seismic Design Category B Page 2 of 3 ffi Piers should be reinforced full-length. Reinforcement shouH extend into the grade beams and foundation walls. Additional reinforcememt rnay be required depending on structural analysis. The belling tool should be used immediately upon completftorn of drilling the straight-shaft portion of the pier. The belling tool should be unseO to its full capaci- ty. Casing should be available on-site to prevent caving of sorTs into pier holes. Piers should be carefully cleaned prior to placing concrete. C,oncrete should be on-site and placed in the pier holes immediately after the hdhs have been drilled, cleaned and observed. We recommend concrete with a mirniinnum slump in the range of 5 to 7 inches to reduce possibility of voids in the bdhd portlon of the pier. lnstallation of drilled piers should be observed by a represenntative of CTLIT to verify subsoils are as anticipated and to observe the contracfofs installation technique. We are available to discuss the contents of this letter. Please contd us if you have questions or need additional information. CTLITHOMPSON, tNC.Reviewed by: u- 2. 5. 4 5 ffi F. Barbone, Division Manager ANDOVER MANAGEMENT GROUP 2f4 CENTER DRIVE CTLIT PROJECT NO. GS06693.001-125 res D. Kellogg, P ncipal Engineer Page 3 of 3