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HomeMy WebLinkAboutSoils Report for Foundation DesignHuddleston-Berry Engineering & Tes(ing, LLC Apnl2l,2025 Project#02997-0001 Stephen and Jennifer Wells 540 Panoramic Drive Silt, Colorado 81652 Subject: Geotechnical Investigation 540 Panoramic Drive ADU Silt, Colorado Dear Mr. and Mrs. Wells, This letter presents the results of a geotechnical investigation conducted by Huddleston-Berry Engineering & Testing, LLC (HBET) at 540 Panoramic Drive in Silt, Colorado. The site location is shown on Figure 1. The proposed construction is anticipated to consist of a new Accessory Dwelling Unit (ADII). The scope of our investigation included evaluating the subsurface conditions at the site to aid in developing foundation recommendations for the proposed construction. Site Conditions At the time of the investigation, the western and eastern portions of the site were occupied by an existing residence and a pond, respectively. The remainder of the site was open and generally sloping down from the west and east to the south of the pond. Vegetation consisted primarily of weeds, grasses, and sparse trees. The site was bordered to the north, west, and east by rural residential/agricultural properties, and to the south by Panoramic Drive. Su bsurface Ipvestisation The subsurface investigation included six test pits as shown on Figure 2 - Site Plan. The test pits were excavated to depths of between 6.0 and 8.0 feet below the existing ground surface. Typed test pit logs are included in Appendix A. As indicated on the logs, the subsurface conditions encountered at the site were slightly variable. Test Pits TP-I, TP-z, and TP-3, conducted to the west of the pond, encountered 1.0 foot of topsoil above brown, moist to wet, medium stiff to soft lean clay with sand soils that extended to the bottoms of the excavations. Groundwater was encountered in TP-l, TP-z, and TP-3 at depths of between 4.0 and 7.0 feet below the existing ground surface. Test Pits TP-4, TP-5, and TP-6, conducted to the east ofthe pond, encountered 1.0 foot of topsoil above brown to reddish-brown, moist to wet, medium stiff to soft sandy lean clay soils that extended to a depth of 4.5 feet in TP-4 and to the bottoms of the excavations in TP-5 and TP-6. The lean clay soils in TP-4 were underlain by brown to gray, moist, medium dense clayey sand soils that extended to the bottom of the excavation. Groundwater was not encountered in TP-4; however, groundwater was encountered in TP-5 and TP-6 at respective depths of 5.0 and 6.0 feet at the time of the investigation. 2789 Riverside Parkway Cnand Junction, Colorado 81501 Phone: 970-255-8005 Info@huddlestonberry.com 540 Panoramic Drive ADU ,A.#02ss7-000t (iftB;J)H*l**il;lHo4/21D5 v " Laboratorv Testine Laboratory testing was conducted on samples of the native soils encountered in the test pits. The testing included grain size analysis, Atterberg limits determination, natural moisture content and density determination, swell/consolidation testing, and maximum dry density and optimum moisture content (Proctor) determination. The laboratory testing results are included in Appendix B. The laboratory testing results indicated that the native clay soils are moderately plastic. In addition, the native clay soils were indicated to be slightly expansive, with up to approximately 0.4o/o expansion measured in the laboratory. The native sand soils were indicated to be slightly plastic. In general, based upon the Atterberg limits and our experience with similar soils in the vicinity of the subject site, the native sand soils are anticipated to be slightly collapsible. Foundation Recomme4dations Based upon the results of the subsurface investigation and nature of the proposed construction, shallow foundations are recommended. Spread footings and monolithic (turndown) structural slabs are both appropriate foundation alternatives. However, as discussed previously, the native soils range from slightly expansive to slightly collapsible. Therefore, in order to provide a stable bearing stratum and limit the potential for excessive differential movements, it is recommended that the foundations be constructed above a minimum of 24-inches of structural fill. Due to their plasticity, the native clay soils are not suitable for reuse as structural fill. Flowever, the native sand soils are suitable for reuse as structural fill. Imported structural fill should consist of a granular, non-expansive, non-free draini?s material with greater than 10% passing the #200 sieve and Liquid Limit of less than 30. However, all proposed imported structural fill materials should be approved by HBET. For spread footing foundations, the footing areas may be trenched. However, for monolithic slab foundations, the structural fill should extend across the entire building pad, arcato a depth of 24- inches below the turndown edges. Structural fill should extend laterally beyond the edges of the foundation a distance equal to the thickness of structural fill. Prior to placement of structural fill, it is recommended that the bottoms of the foundation excavations be scarified to a depth of 6 to 8-inches, moisture conditioned, and re-compacted to a minimum of 95o/o of the standard Proctor maximum dry density, within +2Vo of the optimum moisture content as determined in accordance with ASTM D698. However, as discussed previously, soft soils and shallow groundwater were encountered in the subsurface and this may make compaction of the subgrade difficult. It may be necessary to utilize geotextile and/or geogrid in conjunction with up to 3O-inches of additional granular fill to stabilize the subgrade. HBET should be contacted to provide specific recommendations for subgrade stabilization depending upon the actual conditions encountered during construction. 2V:9008 ALL PROJECTS\02997 - Stephen md Jmifer Wells\0297-0001 540 Pmoramic Drive900 - Geo\02997-0001 LR04l625.doc 540 Panoramic Drive ADU #02997-0001 04/2rD5 Structural fill should be moisture conditioned, placed in maximum 8-inch loose lifts, and compacted to a minimum of 95% of the standard Proctor maximum dry density for fine grained soils or modified Proctor maximum dry density for coarse grained soils, within *2Yo of the optimum moisture content as determined in accordance with ASTM D698 or D1557C, respectively. Structural fill should be extended to within 0.l-feet of the bottom of the foundation. No more than 0.I-feet of gravel should be placed below the footings or turndown edge as a leveling course. For structural fill consisting of approved imported granular materials and foundation building pad preparation as recommended, a maximum allowable bearing capacity of 1,500 psf may be used. In addition, a modulus of 200 pci may be used for approved imported structural fill materials. Foundations subject to frost should be at least 36-inches below the finished grade. Any stemwalls or retaining walls should be designed to resist lateral earth pressures. For backfill consisting of the native soils or imported granular, non-free draining, non-expansive material, we recommend that the walls be designed for an active equivalent fluid unit weight of 55 pcf in areas where no surcharge loads are present. An at-rest equivalent fluid unit weight of 75 pcf is recommended for braced walls. Lateral earth pressures should be increased as necessary to reflect any surcharge loading behind the walls. Water soluble sulfates are common to the soils in Western Colorado. Therefore, at a minimum, cement adequate for Sulfate Exposure Class Sl is recommended for construction at this site. Non-SJructural Floor Slab and Exterior Flatwork Recomme4dations In order to reduce the potential for excessive differential movements, it is recommended that non-structural floating floor slabs be constructed above a minimum of 24-inches of structural fill with subgrade preparation, structural fill materials, and fill placement be in accordance with the Foundation Recommendations section of this report. It is recommended that exterior flatwork be constructed above a minimum of l2-inches of structural fill. I)rainase Recommendations Gradins qnd drainaee are critlcal for the lons-term pefformnnce of the structure and grading around the structure should be designed to carry precipitation and runoff away from the structure. It is recommended that the finished ground surface drop at least twelve inches within the first ten feet away from the structure. It is also recommended that landscaping within five feet of the structure include primarily desert plants with low water requirements. In addition, it is recommended that irrigation, including drip lines, within ten feet of foundations be minimized. HBET recommends that downspout extensions be used which discharge a minimum of 15 feet from the structure or beyond the backfill zone, whichever is greater. However, if subsurface downspout drains are utilized, they should be carefully constructed of solid-wall PVC and should daylight a minimum of 15 feet from the structure. In addition, an impermeable membrane is recommended below subsurface downspout drain lines. Dry wells should not be used. Huddleston-Berry E gin..rin!& Tciling, LLC JV:V008 ALL PROJECTS\02997 - Stephen and Jmnifer Wells\02997-0001 540 Pmormic DriveVO0 - Oeo\02997-0001 LR04l625.doc 540 Panoramic Drive ADU #02997-000r 04t21/25 @*r***,*;Iru As discussed previously, shallow groundwater was encountered at the time of the investigation. Therefore, a perimeter foundation drain is recommended. In general, the perimeter foundation drain should consist of prefabricated drain materials or a perforated pipe and gravel system with the flowline of the drain at the bottom of the foundation (at the highest point). The prefabricated drain materials or gravel should extend along basement walls to within 36-inches of the finished grade. The perimeter drain should slope at a minimum of l.0o/o to daylight or to a sump with pump. Gener?l Notes The recommendations included above are based upon the results of the subsurface investigation and on our local experience. These conclusions and recommendations are valid only for the proposed construction. As discussed previously, the subsurface conditions encountered at the site were slightly variable. However, the precise nature and extent of any subsurface variability may not become evident until construction. As a result, it is recommended that I{BET provide construction materials testing and engineering oversight during the entire construction process. In addition, the builder and any subcontractors working on the project should be provided a copy of this report and informed of the issues associated with the presence of moisture sensitive subgrade materials at this site. It is imnonan ry notu thal the recommendations herein are intgnded to reduce the risk of structural Wvement and/or damaeq to varuinp desriees. associated with volume chanse of the native soils. However. HBET cannot oredlct lone;term chanses in Fubsurface nnigtare conditions and/or the orecise maBryitude or ertefi ofvolume,cha4se in the native soils. Were sienificant increases in subsurface moisture occur due to ooor prading, irnDrooer stormtryater manapement. utilitv line failure. excess irrisation, gr other cause, eilher dufinp gonstruction or the result of actions of the p,ropertv owner. several irghes of movemcnl are oossible, I& addition. anv failure to comolv wi(h the recommendations in lhis reoort releases Huddleston- Berm Enpineerins & Testine. LLC of anv liabllitv with reeard to the structure performance. We are pleased to be of service to your project. Please contact us if you have any questions or comments regarding the contents of this report. Respectfully Submiued: Huddleston-Berry Engineering and Testing, LLC Wayne D. Anderson, P.E. Project Engineer 4V:U008 ALL PROJECTS\02997 - Stephen and Jmifer Wells\029974001 540 Panoramic DriveU00 - Geo\02997-0001 LR04l625.dm F'IGURES 0qPublic.net'" Garfield County, Co Date cr eatedt 4 / t6 I 2O25 Last Data Uploadedz4lt6/2025 2:O7:!6 AM FIGT]RE 1 Site Location Map ocvetooeaWS SCHNEIDER G-OtPAAIAL G)qPublic.net'" Garfi eld County, CO D ate cr ealed: 4 / !6 / 2O25 Last Data Uploaded: 4/L612O25 2:O7 :!6 AM owa.n"auvf,SCHNEIDER CEOSPATIAL FIGURE 2 Site PIan APPENDIX A Typed Test Pit Logs Huddleston-Berry Engineering & Tasting LLC 2789 Riverside Parlnuay Grand Junction, CO 81501 970-255-8005 PROJECT LOCATIONPRo.'ECT NUMBER PRO'ECTMI,IE 540 Panoramic DriveCUENTSlenhen and .lennifer Wells TEST PIT NUMBER TP.{ PAGE 1 OF 1 GROUND ELEVANON TEST PIT SIZE GROUND WATER LEVELS: VnrnnrE oF ExcAvATroN z.o ft DATE STARTED 3118125 CHECKEDBY MAB COilIPLETED 3t18t25 EXCAVATION CONTRACTOR Wiceland lrr ero or ExcAVATtoN 70fi EXCAVANON METHOD Tra*hlBad(hoe AFTEREXCAVANON _ LOGGEDBY TC NOTES ATTERBERG LIMITSs qa 8stut CDul> F:)42J Xasoz 2 ut ILr--Cug (JoIL 5F^ =Euo lil o\E- i/t lljo2:oo Qp J- OtrE 3=o- E 0d 42 o- t--z tIJFzoo U)luztr UJ(L>El-- uJ 5g(L --) ==a IFo-lrjo 0.o o f8DJo MATERIAL DESCRIPTION !3:'! i'*l *c'.'l t.{s- Lean Clay with Sand and Organics (TOPSOIL) v GB 1 16 76133317 Lean CLAY with Sand (CL), brown, moist to wet, medium stiff to soft GB-l: Lab Classilied ? Bottom of test pit at 8.0 feet. Fz(, Io ui Eo ro Huddleston-Berry Engineering & Testing IIC 2789 Riverside Parkway Crrand Junctior! CO 81501 97&255-8005 PR(I'ECT LOCANONPRAJECT NUITIBER PRO.IECT NAME 54O Panoramic DriveCUENTSlenhen and .lennifer Wells TEST PIT NUMBER TP-2 PAGE 1 OF 1 TEST PIT SIZEDATE STARTED 3118125 CHECKEDBY MAB COIIPLETED 3t18t25 EXCAVANON CONTRACTOR Wisaland t AT END OF EXCAVATION 4.5 ftBY TC EXCAVAilON METHOD Trackh/Backhoe GROUND ELEVANOil AFTEREXCAVATION _ GROUND WATER LEVELS: Varnur oF ExcAvAnoN 4.s ft LOGGED NOTES s EllJ ootI| E. au? F:) x8soz z LrJ TLr-ciug ooo- E Ez) tro urSE- 'o.rPt oz =o(J €r- a= J- C) LF(lrs 5=L Fot 42 o- Fz UJFzoG'(Jg, Q UJz Ll- rF(L lrj c) c) Es(, MATERIAL DESCRIPTION UJL>EFt! 5g(L- =z(tt Lean Clay with and Lean CLAY with Sand (cl), brown, moist to wet, medium soft to of test at 6.0 F2o o o -6 Io UJFoUo c? o.l- tr, IJJo =fz tso. F.n lrJF l!o lrJo o- o 'co .c E Ec (Eo alc zoF (JI out atc. ut =z bul atr o. OJ "t BO oF€ hn o bI) H € (J .t6ra ts5c00 <h EKdo U5 .9 0, = o o E ttc(g o o n (t, zlrl3(t Eut @ =2 F(J tu atro. H o, o. oulF IEqrt ltqt zo oxul ILo ut = lr zotr e(tx UJ ILoo2lrl k Nr 2o ulJuI ctz3ou,(9 g rt 5trul =o23oEo zotr ox UJd EI E ll:t(\to (') ouI UI o. =o(J C(! o IA; oo .Yo(!o vo(E LF dt ooulYoluE(, t |J)$t o c4t ogI t tt, uJ o Eo o E zoo2o ox uJ oo I UJ =2otr ox UI oF oolrlooo (u) HId30 eol clHdwc zotrILtoa LrJo J tulF u3snnN :ldAt 3]dt/[VS (oou) % AU3AOCSU (snrvn N) sINnoc MO']S 0st)'N3d l_3vcod 0cd) J.M IINN AUC (vJ rn=rruoc SUnISlot l (,EulutroF ffi=FJF Ftul INSINOC SSNII llttll-1olnofl il14t] Slls\fld XSONI Allclrsvrd 7l'. rr '-,1 '\. sr'.'.-:1.' ilr' .-.1....1..'-\ ._?.'.-.r J6g) 0-oF aho.E tE Eo E a! ! (! U) '5 as6c(o o)J o .E o E Eo E.;dl Bo .9o E :o .Cl t) !tE(go .F Joc(!tEooJ6 rl o OJ q co (o o, oo o Eo o(! J_Oe'8\fl 0t9 @ + o toz I Ilo C)tuFoUo Huddleston-Berry Engineering & Testing LLC 2789 Rivenide Paftway Grand Junction, CO 81501 97U255-8005 TEST PIT NUMBER TP4 PAGE 1 OF ,I CUENT Steohen and Wells PRO.IECTNATIE 5y'.O Panoramin llrivn PRo.JECT NUMBER PRO'ECT LOCANON DATE STARTED 3118125 coiTPLETED 3t18t25 GROUNDELEVANON TEST PITSIZE EXCAVAflON COI'ITRACTOR Wiseland GROUND WATER LEVELS: EXCAVATION METHOD Trackh/Backhoe AT NilE OF EXCAVANON Drv LOGGEDBY TC CHECKEDFY MAB AT EiID OF EXCAVATION Drv 1{OTES AFTEREXCAVATION IL (L r= o o EEtr-o MATERIAL DESCRIPTION UJ o->0(Fur 5gO-->z (h s fia as uJt oGeFfAZJ 'asaz 2 uJIFC irJ "eooL b 3 F^ 20 =cL to 'u9E:' lz bD FrOz =o(_) ATTERBERG LIMITS Fz lrJF2OG(J3l ouiz IL 9r- )- o F-F 3=L F0il 691=o 25 '..:.' : ?'*! :!'r.'! r'"J t) Sandy Lean Clay with Organics (TOPSOIL) Sandy Lean CLAY (CL), brown to reddish-brown, moist, medium stiff GB-1: Lab Classified MC 1 108 '14 5n w GB 1 I 33 17 16 64 Clayey SAND (SC), brown to gray, moist, medium dense GB-2: Lab Classified g GB 2 6 25 17 I 37 Bottom of test pit at 8.0 feet. Huddleston-Berry Engine€ring & Testing LLC 2789 Riverside Parkway Grand Junction, CO 81501 97G255-8005 TEST PIT NUMBER TP-s PAGE 1 OF 1 PROTECT MilE 540 Panoramic Drive PRO.'ECTLOCANONPROJECT NUMBER CUENT Stebhen and Jennifer Wells TEST PIT SIZEDATE STARTED 3118125 CHECKEDBY MAB COI'PLETED 3nU25 EXCAVANON COiITRACTOR Wiseland lnr eno or ExcAvATroN 5.0 ftBY TC EXCAVAilON METHOD Trackh/Backhoe GROUND ELEVANON AFTEREXCAVANON _ GROUND WATER I-EVELSI: Varnue oF ExcAVAnoN s.o ft LOGGED NOTES IFo- uJ(] () *-8t-(9 MATERIAL DESCRIPTION ul.L>EFUJ tr1 @J>(L->z a s ga 8s UJ E. au = F:)AZJ HE'"oz zu&FC i.u l9 ooo- E F^205s E.o u.rSE:- 'aY) -Fa2>oc) Or a= J C) LF(tl =5= o- F od 42 Fz[JFzoooulz TL Sandy Lean Claywith Sandy Lean CIAY (d), brown, moist to wet, medium stiff to soft test pit at 6.0Boftom Huddleston-Berry Engineering & Testing LLC 2789 Riverside Parkway Grand Junction" CO 81501 97U255-8005 TEST PIT NUMBER TP.6 PAGE 1 OF 1 PRO.IECT LOCATIONPROJECT NUMBER PR(NECTNAIE &lO Panoramic DriveCUENTStenhen and Jennifer Wells GROUND ELEVANON TEST PITSIE GROUND UIATER I.EVEI.S: COIIPLETED 3N425DATE STARTED 3t18t25 EXCAVANON CONTRACTOR Wiseland C}IECKED BY MAB Ver nur oF ExcAVATToN 6-0 ft llr eroor ExcAvAnoN 6.0 ff EXCAVATION i'ETHOD Trackh/Bac*hoe AFTEREXCAVANON _ LOGGEDBY TC NOTES F 0d 6e 5=o Fz LrjFzoo U)ul2 TL uto->tFut 5gO-->z a s {a I o'- uJt U) UJ> F:f Xasoz z lJ.l o- FulY C)oo- 5 Ezl d.a H9 -FLA'.nYJ Oz>oo Qr- a= J- C) LF(lls 5=(L g It-c UJo o E8e.'(t MATERIAL DESCRIPTION Lean Clay with Organics OOPSOIL) to wet, medium stiff to softSandy Lean CLAY Bottom of test pit at 7.0 feet. (! @ TE APPENIDIX B Laboratory Testing Results Huddleston-Berry Engineering & Testing LLC 2789 Riverside Parkway Crrand Junction, CO 81501 97U255-8005 GRAIN SIZE DISTRIBUTION PRO.IECTLOCATONPROJECT NUMBER PRO'ECTNAJI|E 540 Panoramic DrivecuEilTSienhen and .lennifer Wells U,S. SIEVE OPENING IN INCHES I U.S. SIEVE NUMBERS HYDROMETER 3 6 100 95 F II uJ =io u IJJz IL Fz UJoE llJo- 85 80 75 70 65 60 55 50 35 30 25 20 15 10 5 0 100 1 GRA]N SIZE IN MILLIMETERS 0.0.0'l \I -r3 t?I I I:ll qTT \'\\ \\ \ il II\ il\ \:ll \ COBBLES GRAVEL SAND SILT OR CLAYcoarsefnecoarsemediumfine ldentification Classification LL PL PI Cc Cu O TP-|, cB-l g/18 LEAN Cl-AYwith 33 17 16 a TP4, cB-1 3/18 SANDYLEAN 3i'17 16 A TP.f, GB-2 3r{8 CI-AYEY 25 17 8 ldentification D100 D60 D30 D10 %Gravel %Sand %silt o TP-i, GB-l 3t18 9.5 0.2 23.7 76.0 tr TP4, GB-l Sttg 4.75 0.0 36.1 63.9 A GB-2 3t18 4.75 o.1&0.0 62.9 37.1 &q U E.o ooo N66 No Huddleston-Berry Engineering & Testing, IIC 2789 Rivenide Paftway Grand Junctiott CO 81501 97&255-8005 ATTERBERG LIMITS' RESULTS cuEilT Stanhen and .lennifer Wells PROJECT NAilE 540 Panoramic Drive PRO'ECTNUMBER 029974001 PR(UECT LOCANON @ @ P L A s T I c I T I N D E X 50 40 t 1 CL-ML @ @ LIQUID LIMIT Specimen ldentification LL PL PI #200 Classification o TP.I, GB.{3r{8 3:|17 16 76 LEAN CLAYwith SAND(CL) a TP4, GB-{3/18 3l!17 {6 64 SANDY LEAN CLAY{CL) A TP4, GB-2 3fi8 25 17 I 37 cl.AYFf SAND(SC) of, Fz6 c.o ui E(f Huddleston-Berry Engineering & Testing LLC 2789 Riverside Parkway Grand Jrmction, CO 81501 97A-255-8005 MOISTU RE.DENSITY REIATIONSHIP PROJECTLOCAnOil Silt. CO PROJEGT N TiE 54O Pannramic Drive PROJECT NUMBER 02s974001 CUENT Stenhen and Wells Jl \ \ \ \ \ 't \ 't \ \ \7 \ / / / \/ T \ \ \ \ Sample Date: Sample No.: Source of Material: Description of Material: u1u?o25 25-0185 145 TP4.GB-{ SANDYLEAN CLAY(CLI Test Method (manual):ASTM D698A 140 135 TEST RESULTS Maximum Dry DensitY 1J2'5 PCF Optimum Water Content 15'O o/o 130 GRADATON RESULTS (% PASSING) #200 #4 314: u {00 100125 o CLf6z UJo do ATTERBERG LIMITS 20 LL PL PI 33 17 {6 115 Curves of 100% Saturation for Specific Gravity Equalto: 110 2.80 2.74 2.60 105 100 95 90 5 15 WATER CONTENT, % 0 10 25 30 Huddleston-Berry Engineering & Tasting, I,LC GONSOLIDATION TEST Riverside Parkway Grand Junction, CO 81501 970A55-8005 CUENT Steohen and Wells PROJECT NAJUE 540 Drive PRo.'ECT NUiIBER 02997{001 PRA'ECT LOCANON SiIt, CO 0.9 1.0 1.1 1.2 1.3 si E.t- U) 1.4 1.5 1.6 1.7 1.8 1 I 10,0001001t STRESS, psf Specimen ldentifi cation l"MC% \ \ \ {) \ \ \ \ \ \ a TP.{, MC-1 2.O Classification 108 14e 6 o ?NooNo z tFa Joozoo