The URL can be used to link to this page

Home My WebLink AboutSubsoils Report for Foundation Design 11.16.17GEOLOGIC REVIEW AND SOILS ENGINEERING REPORT 13100 COUNTY ROAD 204 DE BEQUE, COLORADO Prepared For: Colorado Building Systems Prepared By CAPSTO'VE WEST, LLCENTERPRTSES GEOTECHNICAL AND MINING ENGINEERTNG TESTING AND INSPECTION SERVICES óI8 PARTEE DRIVE GRAND JUNCTION, CO 81504 PHoNE (970) 250-5531 ma rti n @ca pstonewest.com November 16,2017 JobNo.4142 CAPSTANE ENTERPRISES WEST,LLC GEOTECHNICAL AND MINING ENGINEERING TESTING AND TNSPECTION SERVICES ÓI8 FARTEE ÐRIVE GRAND JUNCT¡ON, CO 81504 PHONE (970) 250-35¡l martln@c¡Þstonewest.com JOB #4143 Attention: November 16,2017 Mark Dearth Colorado Building Systems Grand Junction, CO Subject Foundation Recommendations 13100 County Road 204 DeBeque, CO 81630 As per your request, Capstone Enterprises West, LLC (Capstone) performed a geotechnical ínvestigation on the soils at 13100 County Road 204. The purpose of the work was to determine the nature of the material on site and to make recommendations for the foundation. SITE LOCATION The site is in the east half of the southeast quarter of section 25 Township 6 South Range 99 West. The following map shows the general location' {{l r.' . :z !.{ , F ¿ Capstone EnLerPrises füest, LLC "'¿F 2 Job 4L42 ja SITE DESCRIPTION The property is made up of 2 40-acre parcels that ¡s a combination of irrigated farm land and undisturbed wilderness. The construct¡on site will be in the farmed land. The following images show the property limits and the proposed building site. 3 Jab 4L42Capstone EnterPrises Vüest' LLC ír lìq w GEOLOGIC DESCRIPTION The following geologic map and cross section are taken from the USGS Desert Gulch quadrangle that contains the majority of the property. ¡:,¡ 't; tJ;ñt!Ã¡4 l¡ MITS 3E'3û', ¡l ,.1Ê \&'lfÌ¡:,' :]:l'.1{}" D:ajtt0{¡(ir.f Geology mnp¡ed hy Ronald C Asslsted by Bruce Douglas, Vllo Nuccio, 1980 êa' a 1t., o I"977 and 977, 1980. .:.-:i -?l ;, '.- *i, 8s1 qf Q¡8 qs Qr tuscRiPrror{ 0F }tA¡, t HrrS ÁLtlJvlat DEPôs¡îs (1{ùLÔcE}rE}--?ound cn flôod plains of uaJor slreåua ALLUVIAr FÀN DEPoSITS (IIOLOCENE)--DoEInånL type oÍ ãlluvlun. ltost of váll€y bıttons óf ñåJor Étrgamã covered Blth coâletclng fan depoefts fron dlrtrlbutary gulleye and channels TALUS ÂHÞ SLoPEWASII tgsûSITS (H0LOCENEj--ûn stcep alope.r; grades l&terãlly lnto ¿llugi¡L fa¡¡ deposlts SLUl.lP AND L¡{NDSLIDE DEPOSITS (IìÔLOCINE iNtl PLEtST0CËNE)--Conrnon at, baee of eteep canyon valls; cooe alurpe pettially buríed by PlelÊÈoccne terrace deposlre TERRJTCE nEP0StTs (PI,SISTOCE¡¡E)--¡{ost conôpicuoua leve! 300-400 feer (90-l?0 gl) ebove p¡eaent valley floor. Dlp anay froß c¿nyon rålls 'tÕt{GU¡l oF wAsATcH ITORIIATIOH (EOCENE}-*UoË ¡ly purp!r, û¡rroon, 6nd grayr oatslve GJdsÈoûe nlrh a few le¡tfcular sand*tone ùntts. SÉndsronee are f tte to rudlun gralned, troug,h crossbedded, ¡nd a¡ nn:ch as l0 r¡ thlck. About 70 r¡ thlck wlere erpoeed ln çouthern parr of quadrnngle TY 4 Job 4142Capstone Enterprises Vüest, LLC rfleters feet f\ 9r Îu 3,500 ¡¡l- I Qr 2,000 Tsg qf 6,0ût Tt¡ I,500 The following image is the soil map prepared by the USDA Natural Resources Conservation Service. The Happle soil type is associated with alluvialfan debris flows (channery refers to rock fragments that are thin and flat). The Panitchen soil ¡s associated with flood plains. Based on the USGS and USDA the site will have a large range of material properties due to the variety of materials that make up the debris flows. Tgp 1 qf T 5 Job 4]-42Capstone Enterprises trlest' LLC SU BSU RFACE I NVESTIGATIONS The following image shows the test pit locations excavated by Capstone in January of 2Q17 ' The geologic logs for the test pits is presented below. TEST PIT GEOLOGY TP-1 TP.z TP-3 00 0 Clay W Roots Lt Bm. Sllty ClaY Th¡n Flat Fragmonb TOPSOIL- Clay û Rootg F¡rm Mo¡st Flrm PI 1ı Pt=22 v6ry Moist Clay Clay wl Roots Þry Fim Clay sllt and 222 3 4 6 7 3 4 5 6 7 I 9 'f0 3 4 5 6 7 Clay w/ Gravel 9 l0 6 Job 4142 Dry D€dty = 1o6.3pcf Mo¡sú€ = 12.3* Ory D€reity = lO6.3Pd Dry Denlity = 72.2pcf Capstone EnterPrises Vlest, LLC l0 I.ABORATORY TESTING As noted earlier the Manos Shale has swelling potential and it has been well documented that the Mancos Shale at Spyglass Ridge has definite swelling potential. One method to determine if a certain soil or weak rock has swelling potential is to test it with a Swell/Consolidation test. The Swell/Gonsolidation test consists of placing an undisturbed sample of material in a device that applies a load to the soil. The specimen compacts or "consolidates". After the initial load stabilizes, the spec¡men is saturated, and the specimen will either swell or consolidate further. The results are presented below and on the following pages. Sample lD Dry Density (pcO Moisture Content Swell Pressure (psf) Volume ChangeNaturalSaturated TP-2 at'1.5'106.3 12.3o/o 18.6%3,769 1.30% TP-2 at 2.7'106.3 16.1%21.7o/o 9,118 2.85o/o TP-3 @3.0'72.2 18.5%42.9o/o TP-2 Remolded Dry 115.7 6.7Yo 26.8o/o 3,778 3.OOo/o TP-2 Remolded Moist 115.3 11.3%15.7o/o 1,568 0.4jo/o '7 Job 41-42Capstone Enterprl-ses West, LLC TP-2 at 1.5'CONSOLIDATION TEST REPORT 2.000/o 0.00% 1 -2.00o/o 2a É, (r, 2 IJ¡o É, t¡¡o- -4.O0o/o -6.00o/o -8.00o/o -10.007o APPLIED PRESSURE - psf JOB NO" 4142 131oo County Road 204 0r0 I,ATER / Job Number Sample Source Sample Description Natur:al DryDensity Natural Moisture Content Saturated Moi sture Content JOB NO.4142 13100 CountyRoad 204 TP-2 at 1.5' Clay 106.3 pcf 100o/o Relatiw Compaction 12-3o/o -5.5% From Optimum 18.60/o o Job 4142Capstone Enterprises West, LLC CONSOLIDATION TEST REPORT APPUED PRESSURE -psf 'TP-2 ^2.7 2.@To 0.00% -2.000/o -4.OOo/o -6.00% -8.00% -10.00% JOB No. 4142 13100 County Road 204 1 zaú, tt z ¡¡¡oú.luÈ \\\\ \L l0 \ 00U W \ Job Number Sample Source Sample Description Natural Dry Density Natural Moisture Content Saturated Moisture Content JOB NO.4142 TP-2 a!.2.7' Clay 106.3 pcf 16.1o/o 21.7o/o 1 31 00 County Road 204 1 00% Relative Compaction -1.7o/o From Optimum 9 Job 4142Capstone EnterPrises West' LLC TP-3 @3,0'CONSOLIDATION TEST REPORT 0.00% 1 z ú. an zr¡toú,l¡¡ô. -1.00% -2.00o/o -3.00% -4.00o/o -5.00% -6.00% '7.40o/o -8.00% -9.00% -10.00% JOB NO. 4142 13100 County Road 204 AppLlED pRESSURE. psf IfL t0 \DT \ \Wl TER ED \ \ \ \ Job Number Sample Source Sample Description Natural Dry Density Natural Moisture Content Saturated Moisture Content JOB NO. 4142 13'lO0 CountyRoad 204 TP-3 @3.0', Silty Clay 72.2 pcf 680/o Relative Compaction 18.5o/o 0.7o/o From OPtimum 42.9o/o 10 Job 4L42Capstone EnterPrises Vrlest, LLC TP-2 Rêmolded Dry CONSOLIDATION TEST REPORT 4.00o/o 2.O0o/" 0.00o/o za É, .A 2 lr¡() ú,ulô- -2.OOo/o -4.00o/o -6.00% -8.00% -10.00% APPUED PRESSURE -psf JOB NO. 4142 13100 County Road 204 \ \ w rER/) 0 Job Number Sample Source Sample Description Natural Dry Density Natural Moisture Content Saturated Moisture Content JOB NO. 4142 13100 ÕourfryRoad 204 TP-2 Remolded Dry TP.1 115,7 pcf 6.7Yo 26.80/o 1 09% Relative Compaction -11.lYo From Optimum L1 Job At42Capstone Enterprises ltüest, LLC TP-2 Remolded Moist CONSOLIDATION TEST REPORT o.æ% 1 z É, att 2 t¡¡(Jú t¡¡o. -1.000/o -2.OOo/o -3.00% -4.O0Yo -5.00o/o -6.00% -7.OOo/o -8.00% -9.00% -10.00% JOB NO. 4142 13100 County Road 204 APPLIED PRËSSURE - psf (L ( \ 0 \DT \ \ WAT ER ET \ .l Job Number Sample Source Sample Description Natural Dry Density Natural Moisture Content Saturated Moisture Content JOB NO. 4142 13100 County Road 204 TP-2 Remolded Moist Remolded 115.3 pcf '109% RelativeCompaction 11.3% 4.5% From OPtimum 15.7% The formational shale samples from both test pits demonstrated swelling when inundated with water A second method to determine swell potential is the Atterberg Limits Test wh¡ch gives an indication of the mechanical properties of fine grained materials. The first part of the test is to determine the Plastic Limit of the material. Then the Liquid Limit is determined. The difference 72 Job 4L42Capstone Enterprises West, LLC between the Liquid Limit and the Plastic Limit is defined as the Plasticity lndex. Swell potential based on the plasticity limit (Pl) are shown below. Plasticity lndex (Pl)lnherent Swelling Capacity 0-15 Low 10-35 Medium 20-55 High 35+Very High (After Seed et al. 1962) The following table presents the results of the Atterberg Limits testing Material Source Depth LL PL PI TP-z18"-32"TP.1 1',-2 37 19 18 TP-26',-7',TP-1 3'4'38 22 16 rP-27'4',TP-2 0'-.5'44 21 22 1P-32'4'.TP-2 1'.-2',41 27 14 Composite TP-2 TP-3 TP.2 1A'.42 19 23 13 Job 4L42Capstone Enterprises Vriest, LLC 50 20 10 4142 13100 County Road 204 DESIGN CONCERNS UNIFIED SOIL CLASSIF¡CATION CHART 40 60 LTQUTD LIMIT (LL) 80 14 Job 4L42 70 60 t- xr¡¡ 406 =Í-g F.ø30 L 0 200 100 : TP-218"-3?' A TP-26l7' ¡ TP-2 7'€' + TP-32'4' + Composite TP-2 TÞ3 CH / ,{^, CL CL,\Y(3) {f .t / t A S ILT :M) MH onO H M ML ìoL Capstone Enterprises hlest, LLC The alluvial and colluvial sediment at this site are derived from shales and mudstones that are easily weathered to plastic clays. These clays exhibit significant swelling characteristics and are not suitable for foundation construction. Conditions below the foundation may present potential movement problems when moisture conditions change. To minimize the potential of movement, the foundation should be isolated from the potential problem. This can be achieved by any of the following methods: o Anchoring the foundation to formational material below the potentialactive zone. . Removing the potentially active materials and replacing them with suitable material. r Building a foundation that can tolerate movement, both due to soil reaction and post movement leveling operations. Each method has certain costs and levels of risk. lt is impossible to give a numericalvalue to the risk associated with alternative foundation systems. However, the risk is always increased by changes in the moisture content. Controlling surface water is imperative. The TP-2 sample lrom 2.7 feet displayed a swell pressure of approximately 8,100 pounds per square foot with volume changes of approximalely 2.85o/o. Should a 10 foot thick zone of this material become saturated this could cause a 3.4 inch movement of the foundation. This type of movement is rarely uniform across the foundation. Differential movement of this magnitude can cause significant damage to drywall, flooring and concrete flatwork. DEEP FOUNDATIONS The preferred method is to isolate the foundation from the potentially active zone. This is generally accomplished with a deep foundation system such as caissons or piling techniques. The nature of the Plastic Shales makes it difficult to balance the dead-load requirements with the bearing capacity. The consolidation exhibited in the shale before saturation shows that this material is not capable of supporting high dead load pressures required for caissons. There are deep foundation systems that do not rely on deadload, the most common and readily available are: . HelicalPiers . Micro-piles 15 Job 4142Capstone Enterprises V{est/ LLC HELICAL PIERS Helical piers have been used successfully in these types of situations. Helical piers are available in a large range of capacities from 20,000 pounds to 160,000 pounds. The bearing capacity is determined by the torque developed at refusal. The torque is a function of pier geometry and soil strength. Abrupt change in soil strength such as a very hard layer below a soft layer can be problematic. The soft material may not provide enough resistance to force the p¡er into the harder substrata. ln some cases, the pier will spin, developing no torque. ln these cases the pier is only acting as a point loaded pier. Depending on the design load, this may or may not be acceptable. o A test pier should be installed to determine the proper model p¡er to be used. The performance should be documented by the engineer. o Pier spacing should be designed to obtain equal loading on all piers. Piers should not be placed closerthan 4 pier diameters. o Piers should not be over torqued as this may cause damage to the piers. Damaged piers may have to be replaced if damage compromises the integrity of the pier. ¡ The grade beam should be designed to span the distance between piers. The beam must rest a minimum of 4 inches of void form. . A qualified individual should observe and monitor penetration resistance, the torque being applied, pier lengths and other parameters which could effect the pier foundation performance. . Cathodic protection may be required to protect the piers from corrosion. MICRO-PILES Micro-piles would not be suitable for this situation, as a ground to grout bond in soil is quite low. Micro-piles are better suited for rock applications. SHALLOW FOUNDATIONS Soil replacement provides two means of protecting the foundation from movement; firstly, it insulates the swelling soils from surface water and secondly, it distributes the swelling pressure to manageable levels if water should make it to that depth. ln conjunction with heavily a loaded 76 Job 4t42Capstone Enterprises Vriest, LLC foundation the risk of damagíng movement is minimized. The quality of backfill is a very important part of this system. The material needs to granular and non-free-draining. Granular to distribute the load. Non-free-draining to deter surface water from migrating to the subgrade. Crushed rock with approximately 157o minus 200 mesh provides such a product. The engineer should be given a sample of the proposed fillfor project approval FOUNDATION RECOMMENDATIONS For this situation either helical piers or soil replacement are suitable foundations. lf helical piers are desired the design load should be 20,000 pounds and the grade beam should be isolated from the ground with 6 inches of void form. For a replacement soil option, a minimum of 3 feet of non-free-draining structural backfill is required on top of a moisture conditioned and compacted subgrade. The following sketch shows the foundation pad construction details. Landscape Backflll *92olo Compaction at or above Opt MC Imported Backfill to be Granular & Non-Free-Draining 3.0 Min. The maximum allowable bearing capacity should be limited to 6,000 psf with a minimum deadload of 1,000 psf. SLAB CONSTRUCTION Slab-on-grade construction presents a problem where moderate to high expansive soils are present near floor slab elevation because sufficient dead load cannot be imposed on them to resist the uplift pressures generated when the soils are wetted and expand . The only way to prevent damage as a I7 Job 4142 3.0 1.0 Native Solls Native Backf¡ll +95o/o compact¡on +/-2olo opt MC Subgrade Moisture Condltloned and Compacted *95o/o Compaction at or Above Opt MC Capstone Enterprises West, LLC result of stab movement E to construct a strudunlfloor above a wellventilated cmwlspaæ. The floor should be supported on grade beams and piers, the same as the ma¡n structure. Slab-on-grade construction may be used, provided the risk of distress resulting from slab movement is recognized by the owner, and the following precautions are taken to reduce the efiects of movement. . Slabs should be separated from all bearing walls, columns and utility lines with an expansion joint which allows unrestrained vertical movement. ¡ lntêrior nonbearing partitions resting on the floor slabs should be provided with slip joints at the boüom so that slab movement is not transmitted to the upper structure. This detail is also important for wall boards, door frames and stairways. Slip joints which allow at least three inches of vertical movement are recommended. r Water lines and gas lines connected to water heaters and/or furnaces resting on the slab need to be constructed with flexibility to allow for slab movement. Heater ducts must be provided with expandable connections between the furnace and ducts. . Slabs should be provided with controljoints to reduce damage due to shrinkage cracking. lt is recommended controljoints be spaced at 15 feet on centers or less. . The risk of slab movement could be reduced by removing all shale and clayey debris flow encountered within 2 feet below the slabs and replacing it with non-expansive, non-free draining structural fill. This is especially recommended below garage and driveway slabs where water from irrigation is readily available. The backfillshallextend 3 foot laterally beyond the slab. o The top I to 12 inches of subgrade soils should be moisture conditioned to above optimum and re-compacted to minimum 92o/o of ASTM D-698. The moisture content should be maintained until the structural fill is placed. All structuralfill placed below the slabs should consist of non-expansive, non-free draining, granular materialwith a Pl less than 10. The structured fillshould be compacted to at least g5 percent of the maximum Standard Proctor density at moisture content +l-2o/o of optimum BACKFILLING One of the best methods to protect a foundation and flatwork from changes in moisture content ¡s the backfill around the perimeter with a low permeability f¡ll (clayey) and compacting it at 92 o/o of the maximum dry density of the material at above optimum moisture content. The final contours must slope away from the foundation and flatwork at slope greater than 10 inches in the first 10 feet. Runoff 1Q Job 4L42Capstone EnterPrises !üest, LLC should be directed into a drainage channel that transports the water to designed discharge point for the lot. WATER SOLUBLE SULFATES Gypsum crystals were observed in samples. Soluble sulfates present a severe degree of sulfate attack on concrete exposed to these materials. Sulfate resistant cement (Type ll modified) is recommended for allconcrete exposed to the on-site soils. DRAINAGE AND IRRIGATION The success of any foundation and concrete flatwork is contingent upon keeping the sub grade soils at more or less constant moisture content, and by not allowing surface drainage a path to the subsurface. Positive surface drainage away from the structures must be maintained at all times. Landscaped areas should be designed and built such that irrigation and other sudace water will be collected and carried away from foundation elements. The final grade of the foundation's backfïll and any overlying concrete slabs or sidewalks should have a positive slope away from the foundation walls on all sides. We recommend a minimum slope of 10" in the first ten feet; however, the slope can be decreased to 3" in ten feet if the ground surface adjacent to the foundation is covered with concrete slabs sidewalks or pavement. ¡ As much as practical, we recommend, landscaping vegetation that is common to semi- arid climates, with low moisture requirements. A "drip" system of watering could be utilized to keep water usage low. Dry-type landscaping is encouraged. e Areas close to foundation elements, where snow will drift and accumulate, should be protected from standing water during periods of snowmelt. ¡ Landscaped areas should be placed away from the foundation elements, and be designed to drain surface runoff away from the foundation elements. ¡ The structure should have a rain gutter system that directs water away from the foundation elements. . The potable water supply should be located with sand protection of the line, in conjunction with clean gravel prior to backfilling. This would provide a drainage path for water in the event of a waterline leak, away from the foundation. o Water from downspouts should be directed away from the foundation in a well compacted ditch to minimize infiltratíon. An impermeable liner should be used if the backfill is permeable. 19 Job 4]-42Capstone Enterprises V'lest, LLC LIMITATIONS The analysis and recommendations submitted in this report are based drilling, excavations and laboratory testing performed by Capstone. The nature and extent of variation may not become evident until construction. lf variations then appear, it will be necessary to reevaluate the recommendations in this report. It is recommended that the geotechnicalengineer be provided the opportunity for general review of the final design and specifications in order that earthwork and foundation recommendations may be properly interpreted and implemented in the design and specifications. lt is also recommended that the geotechnical engineer, or a qualified geo-technician under his supervision, be retained to provide continuous engineering services during construction of the foundation, excavations, and earthwork phases of the work. This is to observe compliance with the design concepts, specifications, or recommendations and to modify these recommendations in the event that subsudace conditions differ from those anticipated. Any changes from these recommendations must be approved by the engineer in writing. Unapproved changes become the sole responsibility of that individual or company performing that work and assume all liability for the changes and their results. This report, does not constitute a warranty either expressed or implied, as no one can predict the long-tern changes in subsurface moisture conditions resulting from improper grading, excessive irrigation by the home owner or neighbors or other causes during and after construction. lf you have any questions, or if we may be of further assístance, please do not hesitate to contact US Respectfully Submitted : CAPSTONE ENTERPRISES WEST, LLC Martin W. Chenoweth, PE Registered Professional Engineer MWC Job 4142 97784 Capstone Enterprj-ses West, LLC