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Home My WebLink AboutSoils Investigation 11.01.2018CTV CO Engine ering, Inc . Civil Engíneering Consultonts P.O. Box t758 3ó5 West 50 North, Suite W-1 Vernol, Utqh 84078 November 1,2018 Shawn Ruse Clayton Homes 671 23 Road Grand Junction, CO 81505 Dear Shawn, Subiecft Soil Investigation - Haderlie Residence at TBD CR237, S¡lt, CO I am writing to report the findings of a soil investigation that was conducted at the proposed site for the Haderlie residence at TBD County Road 237, Silt, Colorado. The investigation entailed the analysis of one soil sample that was taken at approximately the location and bearing depth of the proposed foundation. Testing of the soil sample included a sieve analysis and Atterberg Limits testing. The results of the soil testing were used to classify the soil sample as 'CL - Sandy Lean Clay' according to the Unified Soil Classification System. A copy of the soil data is included with this letter. CL soils are inorganic clays of low to medium plasticity. ln addition to clay particles, CL soils may contain a fair amount of gravel-, sand-, and sillsized particles. The sample tested contained a sizable proportion (40.7o/o) of pafticles that are sand-sized (#200 Sieve) or larger. Literature suggests that medium to stiff CL soils are likely to have bearing capacities in the range of 4,000 psf . Recognizing that no specific bearing capacity testing was pedormed, I recommend that a more conseruative bearing capacity of 2000 psf be used for design purposes. Over the years, a number of studies have been conducted in an effort to correlate soil expansiveness to atterberg limit data. According to one study, soils with Liquid Limits less than 50% and Plasticity lndices that less lhan 251", generally have a low potential for expansion (Snethen, Johnson, and Patrick, 1977). The soil sample tested was found to have a Liquid Limit of 28"/o and a Plasticity lndex of 9o/". Thus, according to the referenced study, the soil in question is anticipated to have a low expansion potential. lt should be noted that Atterberg Limits testing does not address mineralogy and thus may have a limited ability to reliably predict soil expansion potential. CL soils often are susceptible to frost heave. Methods should be implemented to lessen the likelihood of frost heave. Foundations should extend to below frost depth or be frost-protected by some other means. Water should be kept away from the foundation. Walkways, driveways, and ground surfaces should be graded to flow away from the foundation. Gutter down-spout outlets should be kept at least five feet away from the foundation. Vegetation requiring significant watering should not be planted near the foundation. No testing was done to determine the soil's collapse potential. ln my experience, foundation failures due to soil collapse are generally even more catastrophic than failures due to soil expansion. ln every instance of soil collapse failure that I have investigated, the damaged home was located at the mouth of a pronounced drainage, such as a canyon or gully where the soil has been deposited alluvially by intermittent runoff water flows. Alluvially-deposited soils are typically not very dense and derive their strength from mineral bonds that form between soil particles. When these soils become wet, the mineral bonds dissolve, allowing the soil particles to consolidate (collapse) under any load that is in excess of that which existed when the mineral bonds originally formed. Phone (435)789-WB i Fox (435)789-4485 Emoíl : voncekíng@cívcoengíneering.com . Page2 November 1,2018 Verify that the project site is not at the mouth of any obvious drainage. lmplementing the aforementioned methods for lowering the risk of frost heave is also key to lessening the risk of soil collapse failure. ln summary, the soil under the foundation was not specifically tested to determine its expansiveness but results of atterberg limits testing suggest that the soil has a low expansion potential. Likewise the soil was not specifically tested to determine bearing capacity but was found to be of a type having characteristic bearing capacities in the range of 4000 psf. For design purposes, a 2000 psf bearing capacity is recommended. No specific testing was performed to determine the collapse potential of the soil. The home owner should make every effort to keep moisture from being introduced to the soil near the foundation. Any future purchaser of the home should be apprised of the underlying soil characteristics and the impoftance of keeping moisture away from the foundation. This concludes my report. Please note that this investigation was performed for the purpose of providing general information regarding the soil underlying the proposed home and makes no prediction of foundational performance. This report should not be regarded as documentation of a geotechnical investigation as I am not a geotechnical engineer and this study was not conducted to any generally accepted standard of geotechnical engineering practice. Please contact me if you have questions regarding this report. Sincerely, Vance V. King, PE Engineer CIVCO Engineering, lnc Enclosure Cc:Project File Q. C. Testing. lnc 2944 S 1500 E VERNAL, UTAH 84078 Phone (435) 789-0220 Fax (435) 781-1876 SIEVE ANALYSIS AND ATTEBERG LIMITS CIVCO Engineering - Haderlie residence ll. T. TT,STIHfr - AASHTO T.27 Coarse Gradation Sieve Size Weight Ret.% Ret. %fo|¿l Passing Sieve Size Specs 3" (zsmm)3" 2" lsomm¡z', 1.5" (ez.smm)1.5" '1" (25mm)1 3/4" (tgmm)3t4" 112" (2snn)100 1t2" 3/8" (g.smm)1.7 0.4 99.6 3/8" li4 ølsmm)0.3 0.0 99.6 #4 -ll4 glsmm) WETWT, -#4 ølsmm) DRYWT Total Project No. or Client: Material Type: Distance from CL: native - unified soil classification Depth Date Sampled Stations: Date Tested:10t26t2018 AASHTO T.89 & T.9O Atterberg Limit tiqu¡d L¡mit 28 Plastic Limit '19 Þlast¡c index o :lass¡fication CL sandv lean clav +4 Moisture Data WetWt.431.8 Dry Wt.377.9 H20 Wt. H2O o/o Washed Dry Wt.1s9.8 MF=Tested By CN Fine Gradation Size Weight Ret.7o Ret.% Pass #4 (415nn) #8 (2.36mm) #10 (z.omm)2.5 0.7 98.9 #16 (t.temm) F20 (ssopm)4.7 1.2 97.7 #30 (oooum) #40 Øzspn)9.6 2.5 95.2 #50 (sootm) #60 (zsopm) #80 (taopm) #100 (rsopm)72.3 19.1 76.1 #200 (zspm)63.5 16.8 59.3 -#200 (75um)5.3 Total Remarks SOILCLASSIFICATION(unified)