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Home My WebLink AboutSubsoils Report for Foundation DesignHuddleston-Berry Engineering & Testing, LLC February 14,2025 Project#02205-0002 Casey Sheets 59 County Road 317 Rifle, Colorado 81650 Subject:Geotechnical Investigation Parcel 217927 101002 ADU Silt, Colorado Reference:Geotechnical Investigation, Parcel 217927101002, Silt, CO by Huddleston-Berry Engineering & Testing,LLC for Casey Sheets, February 24,2027 Dear Mr. Sheets, This letter presents the results of a geotechnical investigation conducted by Huddleston-Berry Engineering & Testing, LLC GAET) for Parcel 2T7927101002 in Silt, Colorado. The site location is shown on Figure I - Site Location Map. The proposed construction is anticipated to consist of a new Accessory Dwelling Unit (ADU). 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 northern portion of the site was occupied by an existing residence. The remainder of the site was open and generally sloping down to the southwest. Vegetation consisted of weeds, grasses, and small to large bushes. The site was bordered to the north, west, and east by open land, and to the south by Alta Mesa Road. Subsurface Investigation The current subsurface investigation included five test pits at the site as shown on Figure 2 - Site Plan. The test pits were excavated to depths of between 3.0 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 fairly consistent. The test pits encountered up to 1.0 foot of topsoil above tan, moist, very stiff sandy lean clay soils with gravel and cobbles that extended to the bottoms of the excavations. Groundwater was not encountered in the subsurface at the time of the investigation. Laboratorv Testing Laboratory testing was conducted on samples of the native soils collected from the test pits. The testing included grain-size analysis, Atterberg limits determination, natural moisture content determination, and maximum dry density and optimum moisture content @roctor) determination. The laboratory testing results are included in Appendix B. 2789 Riverside Parkway Grand Jrurction, Colorado 8 I 501 Phone: 970-255-8005 Info @huddlestonbeny. com N '_N \ \ s P arcel 217 927 I 0 I 0002 ADU #02205-O}W 02ltt/25 Huddloston-Berry EnBir.rhg & T.$ing, l,Lc The laboratory testing results indicate that the native clay soils are slightly plastic. In general, based upon the Atterberg limits and upon our experience with similar soils in the vicinity of the subject site, the native clay soils are anticipated to be slightly collapsible. Foundation Recommendations Based upon the results of the subsurface investigation and nature of the proposed construction, shallow foundations are generally recommended. Spread footings and monolithic (tumdown) structural slab foundations are both appropriate alternatives. However, as discussed previously, the native soils are anticipated to be slightly collapsible. Therefore, in order to provide a uniform bearing stratum and reduce the risk of excessive differential movements, it is recornmended that the foundations be constructed above a minimum of Z4-inches of structural fill. The native clay soils, exclusive of topsoil, are suitable for reuse as structural fill; provided particles in excess of 3-inches in diameter are removed. Imported structural fiIl should consist of a granular, non-expansive, W&g i!d!!ng material with greater than l0% 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 area to a depth of 24- inches below the turndown edges. Structural fill should extend laterally beyond the edges of the foundations a distance equal to the thickness of structural fill for both foundation types. Prior to placement of structural fill, it is recommended that the bottom of the foundation excavation be scarifred to a depth of 6 to 9 inches, moisture conditioned, and compacted to a minimum of 95o/o of the standard Proctor maximum dry density, within + 2Yo of the optimum moisture content as determined in accordance with ASTM D698. 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 and 90% of the modified Proctor maximum dry density for coarse grained soils, within + 2Ya of the optimum moisture content as determined in accordance with ASTM D698 and Dl557, respectively. Structural fill should be extended to within 0.l-feet of the bottom of the foundation. No more than O.l-feet of gravel should be placed below the footings or turndown edge as a leveling course. For structural fill consisting of the native soils or 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 subgrade reaction of 150 pci may be used for structural fill consisting of the native soils and a modulus of 200 pci may be used for suitable imported structural fill. Foundations subject to frost should be at least 36 inches below the finished grade. Water soluble sulfates are common to the soils in Western Colorado. Therefore, at a minimum, cement adequate for Sulfate Exposure Class S 1 is recommended for construction at this site. 2Z:\2008 Al-L PROJECT5\02205 - Caey Sheets\o2205-0002 Puc€l 217927101002 ADLA200 - Geo\02205-0002 LR02l425.dm P arcel 217 927 I 0 I 0002 ADU #02205-00a2 a2111i25 Iluddleston-Betty tirBi'r..tnrs e rctins l-LC 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 equivalent active fluid unit weight of 45 pcf in areas where no surcharge loads are present. An at-rest equivalent fluid unit weight of 65 pcf is recommended for braced walls. Lateral earth pressures should be increased as necessary to reflect any surcharge loading behind the walls. Non-Structural Floor Slab and Exterior Flatwork Recommendations In order to limit the potential for excessive differential movements of slabs-on-grade it is recommended that non-structural floating floor slabs be constructed above a minimum of 18- inches of structural fiIl with subgrade preparation and fill placement in accordance with the Foundation Recommendstions section of this report. It is recommended that exterior flatwork be constructed above a minimum of l2-inches of structural fiIl. Drainage Recommendations Gradins and drainase are critical to the lons-term perfonnnnce of the structure. 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 automatic irrigation, including drip lines, within ten feet of foundations be minimized. F{BET recommends that surface 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 drains. Dry wells should not be used. General 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 fairly consistent. However, the precise nature and extent of subsurface variability may not become evident until construction. As a result, it is recommended that HBET 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. JZ:U008 ALL PROJECIS\02205 - Cffiy Sheets\02205-0002 Pucel 2 179271 0l 002 ADU\200 - Geo\02205-0002 LR021425.d@ P arcel 217 927 10 1 0002 ADU #02205-00w 02ltu25 ,,A,. @ Huddlestor-Berfy En8ine.rhs & liJh& t-l-C It is important to note that the recommendations herein are intended to reduce the risk of structaral movement flnd/or damngq to varvins degrees, {tssociated with volume change of the native soils. However, HBET cannot oredict long-tefm changes in subsurface moisture conditions and/or the precise mnsnitade or extent of volame change in the native soils. Where significant increases in subsutfsce maisture occur due to poor gradins. imDroper stormwater msnagement, utilitv line failure, ecess irrteafion. or other cause, either durins construction or the result of actions of the propertv ownen several inches of movement are oossible.In addition, anv failure to cottwlv with the recorylryJndgtiow in this reoort releases Huddleston- Berrv Ensineerins & Testing, LLC of anv liabilitv with regard 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 Submitted : Huddleston-Berry Engineering and Testingo LLC Michael A. Berry, P.E. Vice President of Engineering 4Z:\2008 AI,L PROJECTS\o2205 - Casy Sheets\02205-0002 Prcel 217927101002 AD[A200 - Ceo\02205-0002 LR02l425.dm FIGT]RES G)qPublic.h€t'" Garfi eld County, Co Location llD Date createdt 215/2O25 Last Data Uploaded: 2/512O25 2206:51 AM FIGURE 1 Site Location Map Develoned bvlp SCHNEIDER c€o5P^TrAL G)qPublic.net* Garfield County, Co FIGURE 2 Site PlanDate created: 1/16/2025 Last Data Uploaded: 1/16/2025 2:O5:58AM Developedbye SCHNEIDERc30aPA?lAl APPENIDIX A Typed Test Pit Logs PROTECT NI\ME Parce) Zl7g27'lUW2 ADU PRO'ECT LOGANON SiIt, COPROJECT NUMBER 02205-0@2 Riverside Junctisr, Parkway co 81501 CLIENT Casev Sheets Huddleston-Berry Engineering & Testing LLC 9?0-255-8005 TEST PIT NUMBER TP.{ PAGE 1 OF 1 TEST PITSIZEDATE STARITED 1fi725 @MPIETED 1N7T25 EXCAVATION CONTMGTOR Client CHECKEDBY MAB EXCAVATION METHOD TrackhlBackhoe GROUND ELEVANON LOGGEDBY TC NOTES AFTERB(CAVATION -- AT ENDOF EXCAVATIO{II Dry GROUNDWATERLEIIELS: ATflMEOF B(CAVATION Drv ATTERBERG LIMITSul&>IrFrrl 1gaL::r>2. at) a E8gs ult aG>Fl<2. J;asoz. z. uJoFGill l4 oo(L 5F^ =_Euo -ot-U o\E:- -F tt, Floz =oo o, l=a= J- otrF 3=o Fot 42o- FzulFzoG'O=a LUzit IE IFo-ulo 0.0 o +Et-o MATERIAL DESCRIPTION I GB 1 5 m 17 I 53 Sandy Lean CLAY with Gravel and Cobbles (CL), tan, moid, very stiff G&1: Lab Classified Fz(] a jo Noo o FNoF N J IU Otr A No o @oNNo u)z :lJoo Im of test pit at 7.0 feet. Huddleston-Berry Engineering & Testing LLC 2789 Riverside Parkway Crrand Jrmctigr, CO 81501 970-255-8005 TEST PIT NUMBER TP-2 PAGE 1 OF 1 PRO.TECT Ifl\ME Parcel 2175271O10f)2 NU PROJECT NUMBER PROJECT LOCATION sitr co CLIENT Casey Sheets EXCAVATION METHOD Trackh/Backhoe LOGGEDBY TC CHFCKEDBY MAB DATESTARTED 1N7T25 @MPLETED 1117N5 TEST PIT SIZE EXCAVATION CONTRAGIOR Client ATNMEOF E(CAVATION Drv GROUND ELEVATION t{oTEs ATENDOFEXCAVATION Dry AFTEREXqVATION - GROT' Nfi } WATER LEVEI.S: ATTERBERG LIMITSt!(L>EFut -rtg(L= =2.a s qa 8(-ulE au>Fl ^z.J;3soz z.ulIL FCirg ()o.L E F^ =Eto r-rr;e(r:- tD Floz>oo o, 3=lr otrF 3=& F0t 42o- FzulFz 88a UJztr g IF(L Lrlo 0.0 o: +Et"o MATERIAL DESCRIPTION Sandy Lean CLAY with Gravel and Cobbles (cl), tan, moist, very stiff oN N F si Jol Fz 6 o- jo oz lJa-c0 IouFoI Bottom of test pit at 6.Ofeet. PROTECT nlAME Parcel ?.79271O1ffI2 ADU PRO.TECT I.oCATTON Sitt. COPROJECT NUMBER 02205@2 Riverside Engineering & Testing LLC CLIENT Casey Sheets TEST PIT NUMBER TP.3 PAGE 1 OF 1 Crrand Junctiur, CO 81501 970-255-8005 MMPLETED 1117f25 TEST PITSIZEDATE STARITED 1N7T25 EXCAVATIONCONTMGTOR Client CHrcKEDBY MAB EXCAVATIONMETHOD Trackh/Backhoe GROUNDELF'ANON ATENDOFEXCAVAilON Drv AFTEREXCAVANON _ LOGGEDBY TC t{oTEs GROT'NDWATERLEIIEIS: ATTIMEOFE(CAVATION Drv ATTERBERG LIMITS Fqil 42(L Fz uJFzoG'o= U) UJz l! I IF(Lulo o o o-X sY(, MATERIAL DESCRIPTION ul(L>uFUI sg(L -!>= a s E-- E3 8s UJ E. ai>Fl<zJ Xasoz zul{LFG UJ JA oo(L I F^ =Eto ur;at- i, Pl_Foz.>oo oF a=lJ () FF 3= 1 .ry.:.!i+ {_a.' j ?$r rt r/ rl 2: "!-t' ir r).'^t ? $r: Sandy Lean Clay with Organics (TOPSOIL) 2 3 Sardy Lean CLAY with Gravel ard Cobbles (cl), tan, moi$, very siff oN N Foo di Ja) Fz (9 a C?:)o Noo o FNoF N Boltom of teS pit at 3.Ofeet. Huddleston-Berry Engineering & Testing LLC 2789 Riverside Parkway Grand Junction, CO 81501 9?0-255-8005 TEST PIT NUMBER TP4 PAGE 1 OF 1 PRO.JECf ]I|AME Parce) 217527101@,2 ADU PRO.TECT LOCATTON Sitt, COPROJECT NUMBER O2O5-OOO2 CLIENT Casey Sheets TEST PIT SIZE@MPLETED U17N5DATESTARTED il1725 EXCAVATION CONTMGTOR Client CHECKEDBY MAB EX$VATIONMETHOD Trackh/Backhoe GROUND ELEI'ATION ATENDOF B(CAVATKhI Drv AFIEREXCAVANON _ LOGGEDBY TC ITIOTES GROUNDWATERLEVELS: ATTIMEOF E(CAVATION Drv ATTERBERG LIMITSulI>trFut 5g(L=) =2.a s qa 8sulE au>Fl ^zJXasoz. 2 uJ(L FGi!g oo(L 5F^ZQflJ Eo .uFE--rL1 tD Froz =oo o, f=o= l- oEF q= L Eqd 69 5=o Fz UJFzoG-og ct) [rJztroo TF-^ O- rE o o 3qo MATERIAL DESCRIPTION Sandy Lean Clay with Organics (TOPSOIL) 2.5 Sardy Lean CLAY with Gravel and Cobbles {cl), tan, moi$, very stiff 4NEN Fo(, ai Jaf Fz o o- jo Noo Bottom of test pit at 8.0 feet. Huddleston-Berry Engineering & Testing LLC 2789 Riverside Parkway Grand Junclisr, CO 81501 970-255-8005 PROTECT I|I|AME Parcel A7S271UW2 ADU PROJECT LOGATION SiIt. COPROJECT NUMBER 02205-OOO2 CLIENT Casev Sheets TEST PIT NUMBER TP.s PAGE 1 OF 1 GROUNDELryANON GROUNDWATERLEIIELS: ATilMEOFEXCAVATON Drv @MPLETED 1N7N5 TEST PITSIZEDATE STARITED 1117N5 EXCAVATION CONTMCTOR Client CHFCKEDBY tvlAB EXCAVATION METHOD Trackh/Backhoe ATENDOFE(AVATlOill Drv AFIEREXCAVATION _ LOGGEDBY TC f{oTEs ATTERBERG LIMITS o IF^(L rE o () Irn +d (, MATERIAL DESCRIPTION rrlL>lrF-ut sgIL =r=z U) .:g $a 8sult rnO>Fl ^,2.JHastJ= z.ulILFCirg oo(L 5 F^ =EE.o u.r;eE:' tD FI -Foz =oo o, d> J_ oFF 3=o- F0t 42 Fz u.lFzoG'O= U)utztr E:."! t..sx, $ !.'{ r. ii rr Sandy Lean Clay with Organics (TOPSOIL) Sandy Lean CLAY with Gravel and Cobbles (cl), tan, moist, very diff Bottom of test pit at 3,0 feet. Jtxoe (]- Nooo a N No g) lJ O Id! IO t].tFoU APPEIIDIX B Laboratory Testing Results Huddloston-Berry Engineering & Testing LLC 2789 Riverside Parkway Grand Junctiqr, CO 81501 970-255-8005 GRAIN SIZE DISTRIBUTION PRO.IECT iIAME Parce| 2'7927101'ffJ2 ADU PROJECT LOCAnON Sitt. COPROJECT NUMBER 02205-OOO2 CLIENT Casey Sheets U.S. SIEVE OPENING IN INCHES I U.S, SIEVE NU'BERS I 1m14)2m HYDROMETER6 4 3 21.5 14 20 :n {} FI(, tr3 co trtrtztr Fztrlo E.t! o- 100 95 90 85 80 75 70 65 60 55 50 45 40 35 30 20 15 't0 5 o 100 1 1 GRAIN SIZE IN MILLIMETERS 0.1 o.01 0.001 *, I I I tt \L_ t: n li \ ! :li t: I I \ li :l 'l l: li COBBLES GRAVEL SAND SILT OR CLAY @aIse fine coarse mdium fine Specimen ldentifi cation Classification LL PL PI Cc Cu a TP-l, GB-l 1t17 SANDYLEAN CI-AY(CL)26 17 I D60 D30 D10 ToGravel ToSand %sitt %ClaySpecimen ldentification D100 0.t45 4.6 42.0 53.4oTP-1, GB-l 1t17 {9 NaN Fno {d J (t):l tt NoI o N ulN6z t ATTERBERG LIMITS' RESULTS PR(UECT TtlAME Parcel 21792710,1'C(I2 ADU PrcJECT NUMBER gff,-cnp.z PRO.TECI LOCATTON Sin. CO CLIENT Casey Sheets Huddleston-Berry Engineering & Testing Ll,C 970-255-8005 Riverside Parkway Junctim, CO 81501 @ @ LIOUID LIMIT @ @ 4020 CL-ML 50 40 30 20 10 0 P L A s T Ic I T I N D E X Specimen ldentification LL PL PI #204 Classification a SANDY LEAN CLAY(CL)TP-1, GB-'1t17 26 17 I 53 -Aojo N Jtll OE c N BooNNo U}F :loEr.!d)t I.xt MOISTURE.DENSIW RELATIONSHIP PROTECT ]tlAME Parcel 21752710,1.0(J2 ADV Prc.'ECT NUMBER Affi-opp'2 PRO.'EGI LCICATION SiIt. CO CLIENT Casev Sheets Huddleston-Berry Engineering & Testing, Ll-C Riverside Parkwav Grand Junctisr, CO 81501 970-255-8005 )ul \ I \ \ \\ \\ I \ \ \ \ \ \ \ ,a 7 \\ 7 t 7 \\ \ \ \ \ \ \ \\ \ \ PLLL 26 201 oo-tFaz.ulo E.o 145 140 135 130 125 115 110 105 100 90 1n7t2025 254022 TP.{GB-1 SANDY I-EAN CLAY{CL) Test Method (manual):ASTM D698A TEST RESULTS Maximum Dry Density {23-0 PCF Optimum Water Content 11.5 % GRADATION RESULTTi (% PASSTNG) #200 # 3t4" 53 95 100 ATIERBERG LIMITS PI 17 9 Sample Date: Sample No.: Source of Material: Description of Material: 15 Curves of 100% Saturation for Specific Gravity Equalto: 2.84 2.74 2.60 t di Ja:) Fz (, q l N o o F ! ts N 95 50 10 \A/ATtrR NOhTTtr.\TT OA 20 25 30