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Home My WebLink AboutObservation of Excavation 07.08.2024Ktn Hiffilfi'*11'frurx t':,:.; .'' " i,1 i.:r.f]Ii.,.; ;3,i f.[fJ I 8 tw ,- , I i..ri,,,,l,ry, ,,: : i ;l ,.i., i:.jir.l.. 5020 County Road 154 Glenwood Splings. CO 8160 I phone: (970) 945-7988 lax: (970) 945-8454 I : kagl c'nwood(ri)k Lrntalusa.conr wi,vw, kumdrusa.comAn Ernployes 0wilsd Connpcl'ry Office Locatiorrs: Denver'(l1Q), Parker, Colorado Springs, Forl Collins, Clenwood Springs, and Sumrnit County, Colotado luly 8,2024 Mike Kite 6534 CoLrnty Road 331 Silt, Colorado 81652 Mike.kite2@,aol.com Pro.iect No.24-7-223 Subject: Observation of Excavation, Proposed Log Cabin, 6534 Cor"rnty Road 331, Garfield Courrty, Colorado Dear Mike: As requested, a representative of I(urnar & Associates, Inc. observed the excavation at the subject site on June 26,2024 to evaluate the soils exposed for fourrdation sr"rpport. The findings of our observations and recommendations forthe foundation desigrr are presented iri this repoft. We previously conductecl a subsoil stucly foL design of loundations at the site and preserttcclour frndings in a report dated June 5,2024, Project No.24-7-223. The proposed log cabin will be a single-story pre-engineered structure over a partial basenrent level. The cabin has been designed to be supported on spread footings sized for an allowable ' bearing pressure of 1,500 psL At the tirne of our visit to the site, the foundation excavation had been cr.rt in 2 levels frorn 3 to 9 leet below the adjacerrt ground surface. The soils cxposed in thc bottom of the excavation mainly consisted of claystone bedrock, Results of swell-corrsolidatiorr testing perfornred on samples tal<en from the site, shown on Figures 1,2 and 3, indicate the soils and becl'ock possess variable cornpressibility and expansion potential when wetted under light surcharge loa'ding. No free water was encountered in the excavation and the bedrock was slightly rloist. The claystone bearing conditions exposed in the excavation are consistent with those previously encountered on the site. We previously recommended the cabin be for-rnded on a drilled pier foundation that would extend the bearing level down to a zone of relatively stable moisture N |ati $ N content and resist potenti spread footings sized for al foundation an allowable heave and building distress The current des is for ssure of I s00 don natural soi or as designed the cabin will likely be sLrbject to foundation movement and structural distress. Considering the relatively low expansion measured on the sample tested at cut depth, a lower risk would be to remove 3 feet of the cla ystone bedrock and eit with ASS structural fill lm orted u ar structural fill should be moisture conditioned to near such as CDOT optimum moisture y and extend at lwor;ld be "oTiili?id'Effipu-ed to at least 98 percent maximum standard Proctor densit least one-foot beyond the footing edges et of fsuitable for spread footings designed for the assumed allowable bear lng pressure o Mike Kite Ivly 8,2024 Page2 1,500 psf. We should be contacted to observe the completgcl sub-excavation of the fbundation. Othcr rccommcndations prcscnted in our previous report which are applicable should also be observed, The recommendations submitted in this letter are based on our observation of the soils exposed within the foundation excavation and the previous subsurface exploration at the site. Variations in the subsurface conditions below the excavation could increase the risk of foundation movement. We should be advised of any variations encountered in the excavation conditions for possible changes to recommendations contained in this letter. Our services do not include determining the presence, prevention or possibility of mold or other biological contaminants (MOBC) developing in the future. If the client is concerned about MOBC, then a professional in this special field of practice should be consulted. If you have any questions or need further assistance, please call our office. Sincerely, Kumnr & Asso*l*tes, James H. Parsons, Rev. by: SLP JHP/kac attachments Figures 1 through 3 - Swell-Consolidation Test Results Table 1 - Summary of Laboratory Test Results i' Kumnr & Associntes, lne. @ Prcleet No.34-7-nA$ .t I$ SAMPLE OF: Weothered Cloyslone FROM: Bosemenl NW WC = 6.6 %, DD = 151 pcf EXPANSION UNDER CONSTANT PRESSURE UPON WETTING rlth 0-4546. 3 2 d.:s j1 lrl =th lo zotr o = -loazo<J-2 24-7 -223 Kumar & Associates SWELL-CONSOLIDATION TEST RESULTS Fig. 1 SAMPLE OFr Weolhered Cloystone FROMI Bosemenl SE WC = 6.3 %, DD = 129 pct adbn h lnc. EXPANSION UNDER CONSTANT PRESSURE UPON WETTING 2 ;sv JJ LrJ =a I zotr o =o @zoo 0 1 2 1.0 APPLIEO PRESSURE - KSF I() 24-7 -223 Kumar & Associates SWELL-CONSOLIDATION TEST RESULTS Fig. 2 x il SAMPLE OFr Sondy Silly Cloy FROM: Crowlspoce - Soulh WC = 5.2 %, DD = 105 pcf Sa rdbn ot ADDITIONAL COMPRESSION UNDER CONSTANT PRESSURE DUE TO WETTING 1 t( JJ lrJ =a I zo F o Joazo() 0 -1 -2 -3 -4 -6 -7 -8 I 1.0 't00 24-7 -223 Kumar & Associates SWELL_CONSOLIDATION TEST RISULTS Fig. 3 ,\ Ktnffi['#nr**:nfd** TABLE 1 SUMMARY OF LABORATORY TEST RESULTS No.24-7-223 SOIL OR BEDROCK TYPE Weathered Claystone Weathered Claystone Weathered Sandstone Sandy Silty Clay Weathered Claystone {PSF} UNCONFINED COMPRESSIVE STRENGTH PLASTIC INDEX ("1 ATTERBERG LIMITS (%l LIQUID LIMIT PERCENT PASSING NO. 2OO SIEVE SAND {%l GRADATION (%) GRAVEL NATURAL DRY DENSITY (ocfl 131 t29 115 105 121 (okl NATURAL MOI:STURE CONTENT 6.6 6;.3 4.7 5.2 8.4 SAMPLE LOCATION BOTTOM.OF EXCAVATION Basement Level Northwest Southeast Northeast Crawlspace South North