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Home My WebLink AboutSubsoil Studyc¡RERE€J(, c-ruJz.É,< >EFurz= -CL 8ËoH I¡J ts tt-3ll= óã GEOLOGIC REVIEW AND SOILS ENGINEERING REPORT TRACT44 ANTLERS ORCHARD DEVELOP]TIENT SILT, COLORADO Prepared For: J CaliberGonstruction Prepared By CAPSTOftüE ENTFRPRNSES WEST, u-c GEOTECN.{ NNCAL ANÞ il[/l[þ{TNG ENGNIVEER,INIG TESTTIUG AN¡D ThISPECTION SERVNCES 618 FARTEE DRIVE GRAND JUNCTIO|{, C0 8150/* Pr-roN¡E {9V Aj 250-5551 martin@capstonewest"com June 19,2020 JobNo.4545 CAPSTOruE "'.-:ENTERPRTsFS WESIil Ltc GEOTECfINTCAL AN¡D MTIStrf{G ENGINEERING TESTING AI\¡D INSPECTION SER\TICEs ó¡8 FÂRTEE DRIVE GFA¡¡D JUNC-rIOÌ¡, CO ðt50& PHOr.¡E (97O) 25&5551 martin@cãpÉtonenest.@m JOB #4545 Attention: June 19, 2020 J Caliber Construction Rifle, CO Subject:Foundation Recommendations TRACT 44 ANTLERS ORCHARD DEVELOPMENT SILT, COLORADO Per your request, Capstone Enterprises West, LLC (Capstone) performed a geotechnical investigation on the foundation materials your property off of Harvey Gap Road. The purpose of the work was to determine the nature of the material on site and to make recommendation for the foundation. SITE LOCATION The site is in the southwest quarter of section 36 Township 5 South Range 92 West. The following maps show the general location. SITE DESCRIPTION The property sits on the flank of a resistive sandstone hill as shown in a later Google Earth isometric image. The site is essentially undisturbed grazing land. The central topographic feature of this lot is a mild ridge that runs diagonally across the property from the southwest corner to the northeast corner. The ground slopes off to the northwest, the south west and the southeast at approximately 5%. 2 Job 4545Capstone EnterPrises Vüest, LLC raÈ Iü t¡t út Site út s¡llr +ßiItl tattat r:l:J¡ i GEOLOGIC DESCRIPTION Bedrock in the area has been mapped as the Sandstone Unit of the Wasatch Formation (Twss). The USGS su¡face geology map is presented on the following page with the approximate property line. 3 Job 4545Capstone EnterPrises Westr LLC EtEt qo.CþJTT 'JseM ses-frdrêfug euofsdeJ'e6eull qye¡¡ e¡6oog oqt uoql ueql 'e6ed ôulrvro¡¡o¡ otlt uo poluosold e¡e s6o¡cl6o¡oe6 oql'uotlcnllsuoc ol.loud sìseqlos eul¡ Á¡.redold eqt qsllqelso ol'u!peÁeruns oq ol poou llt^ outl ÁUedold lenlce oql 'outl ÁUedo¡d elerllxo¡ddeeql pue suo[ecol lld ]so] eqt s6oqs e$eull $ut¡ro¡¡o¡ oql 'ollsqo^5¡g Á¡unoc plollJeÐ orlt ruorl popeolu/r^op seM eul¡ rQledotd eq1 'quefe¡6oog tut popeol olo/r^ soleu¡plooc oql 'SdÐ ploqpueq e 6ulsn ul peÁerunsolo/v\ suotlecol otlt olts otlt te slld lsol ? Jo uollenecxe oqt polcollp ouolsdeCSNOIIVÐIISSAN I f CVIUNSs NSâ.-aIt-qFãÉFãFãæEl; lqÇÇq{-+-4*-iæTãËaÉ-æã-4-ffilq.F-æFæm#.r---s* [î'l-çIF.æ fqlôaryffid&m-*-*fã laææf t_|æræaf ılã;-Çr-[Er-ræ-*f-!lôtrffim*ræ[-WÛæt_.1æIL;JÜ@/{sat¡it o 0 1 2 3 4 2 3 7 I I 1A10 -rP"r TP.3 TEST PIT GEOLOGY TP-2 Topsoil- Gayey Silt W/ Roots Mo¡t Silt Pl=9 o Topæil- Siltw/ Rocms Firrn SilS tay P!=9 Drlt DensttY = 97.8 Pd' i{o¡sture = 16.2% Topsoil- Clayey Silt ld/ Roots Þtoit Silt PI=9 Top6o¡Þ Silt usl Ro'ots Þry Fnn SiþClay EI =v Gravel in Tar¡ Silt l{atrbt Dry FirmSilW(lay BY DamsüY = fm-g Pcf fi¡ûisfu¡re = 7-34ú 4 5 5 6 7 9 trP-4 0 1 2 I 2 3 4 5 b v ð G 10 4 g 6 'r ü I t0 5 Job 4545 ü d-d t Capstone EnterPrises West, LLC 4-t I..ABORATORY TESTING The suitability for foundation material is generally determined by two tests: the Swell/Consolidation test and the Atterberg Limits test. The Swell/Consolidation 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 specimen is saturated, and the specimen will either swell or consolidate further. The results for the native materials are presented on the following page. The Atterberg Limits Test 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 between the Liquid Limit and the Plastic Limit is defined as the Plasticity lndex. Swell potential based on the plasticity limit (Pl) is shown on the following page. 6 Job 4545Capstone Enterprises Vüest' LLC TP-3 at4 ft CONSOLIDATION TEST REPORT 0.00% 1 -1.OOo/o -2.OOo/o -3.OOo/o z É.¡-U' Þ-zl¡lo É, ¡.r¡fL 4.O0o/o -5.00% s.00% -7.00% -8.00% -9.00% -10.00% APPLIED PRESSURE - Psf Job No.4545 T¡act44 t- DOr0 WA ERAI \ Job Number Sample Source Sample DescriPtion Natural Dry Density Natural Moisture Content Saturated Moisture Content Job No.4545 'lracl44 TP-3 at 4 fr Silty Clay 97.8 pcf 16.2o/o 25.60/o 1 Job 4545Capstone EnterPrises Vrlest/ LLC CONSOLIDATION TEST REFORT TP-4 at 3.5 fr 0.00% 1 -1.00o/o -2.OOo/o -3.00% z ÉFo¡-zt¡loÉl¡¡ o- 4.O0olo -5.00% 4.00o/o -7.OOo/o -8_00% -9.00% -10.00% Job No.4545 Tract 44 APPLIED PRESSURE- psf 0)0r0 TERI DW¡ \ \ \\ \ \ \ \ Job Number Sample Source Sample Description Natural Dry Density Natural Moisture Content Saturated Moisture Content Job No.4545 Tracl44 TP4 at 3.5 ft Silty Clay 105.8 pcf 7.3o/o 17.9o/o Plasticity lndex (Pl)lnherent Swelling Capacity 0-15 Low 10-35 Medium 20-55 High 35+Very High (After Seed et al. 1962) B Job 4545Capstone EnterPrises Vrlest, LLC The results presented below indicate there is a low potential for swelling for the silty clay material. Material Source Depth Liquid Limit Plastic Limit Plasticity lndex Swell Potential Debris Flow Fines TP-1 2-9 ft 28 19 I Low Debris Flow Fines TP-2 1-3 ft 31 22 I Low Debris Flow Fines TP.3 1-3 ft 25 18 7 Low The Atterberg Limits Tests indicate the alluvial material is suitable for structural fill if the material is not too coarse. Samples of the Wasatch Sandstone bedrock were also tested to determine how they would react to excessive water. The following photos are the before and after photos for the formation sandstone being soaked overnight. There was no deterioration of the rock only a crack opening up and dust being washed off the rock. 9 Job 4545Capstone Enterprises West, LLC DESIGN CONSIDERATIONS As mentioned earlier, Sandstone Unit of the Wasatch Formation is the bedrock unit in this area. The alluvial and colluvial sediments overlaying the bedrock are suitable for structural fill when properly compacted. The alluvial material at the site is low plasticity (Pl's of 7 to 9) this indicates that it is suitable for structural fill provided the any cobble sized rock (3" or greater) are not included in the fill. lf this cannot be avoided, the foundation pad should be capped with a layer of fine aggregate' DESIGN RECOMMENDATIONS We recommend this residence be constructed on a stemwall footer foundation. The foundation should rest on a compacted mat made up of the native materials or impofted aggregate. The mat should þe a minimum of 1 thick; one foot of soil removed and replaced afterthe subgrade has been moisture conditioned and cqmpacted. A maximum bearing load 10 Job 4545Capstone EnterPrises West' LLC of 1,250 psf should not be exceeded. A lateral earth pressure of 45 psf per linear foot should be designed for. The following sketch shows the general requirements for the foundation pad. 'ORGAINICS TO BE REMOVED ]FRO]M IFOUNDATION |FOOTPRIINT BACKFILLING One of the best methods to protect a foundation and fla¡ryork from changes in moisture content is the backfill around the perimeterwith a low permeabilityfill (clayey) and compacting it al92o/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 1 0 feet. Runoff should be directed into a drainage channel that transports the water to designed discharge point for the lot. DRAINAGE AND I RRIGATION Care must be taken to prevent stormwater from getting near the foundation. At this site an interceptor swale should be built uphill from the residence to divert water away from the structure. 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 surface water will be collected and carried away from foundation elements. The final grade of the foundation's backfill and any overlying concrete slabs or sidewalks should have a positive slope 11 Job 4545 iNativeiBackfill +95þ/D Cornpaction at +/- 2o./o Opt rMC Subgrade ìMo¡sture Cond itîor¡ed and Co'mpacted +qqo./ñ Côrnnartion at +l- 29/o nnt lMa 2.0 1 :1 0 Capstone EnterPrises West, LLC 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 sudace adjacent to the foundation is covered with concrete slabs sidewalks or pavement. . Utility trenches may allow water to travel some distance and reach the foundation pad if left on checked. The water, sewer and dry utility trenches to the residence must be backfilled with a low-permeability (clayey) material to prevent water movement toward the residence. . 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. Drytype landscaping is encouraged. . 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. o The structure should have a rain gutter system that directs water away from the foundation elements. ¡ Water from downspouts should be directed away from the foundation in a well compacted ditch to minimize infiltration. An impermeable liner should be used if the backfill is permeable. r The builder and homeowner must always be careful not to route dra¡nage onto a neighboring lot. LIMITATIONS The analysis and recommendations submitted in this report are based test excavations and laboratory testing peformed 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 geotechnical engineer 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 geotechnicalengineer, ora 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 L2 Job 4545Capstone EnterPrises Vrlest, LLC recommendat¡ons and to modify these recommendations in the event that subsurface 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 constítute a warranty either expressed or implied, as no one c€¡n predict the long-tern changes in subsuface moistçrre conditions resulting from improper grading, excessive irrigation by the home owner or neighþors or other causes during and after construction. lf yo u have any questions, or if we may be of further assistance, please do not hesitate to contact us Respectfully Submitted: CAPSTONE ENTERPRISES WEST, LLC Martin W. Chenoweth, PE Registered Professional Engineer MWC 37784 13 Job 4545Capstone EnterPrises lrlest, LLC