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Home My WebLink AboutB14-0190 GeoTech letter.pdfJune 30, 2014 Elk Meadows Development, LLC Attn: Brian Redinger 141 East Meadow Drive, Suite 211 Vail, Colorado 81657 ., ·· .. ti !_.•.~!I JI ~rrM~ ;"1J![E~ TOWN OF VAIL Job No. 114 086A Subject: Observation of Excavation, Proposed Residence, Lot 3, Elk Meadows Subdivision, 1628 Buffehr Creek Road, Vail, Colorado Dear Brian: As requested, a representative of Hepworth-Pawlak Geotechnical, Inc. observed the excavation at the subject site on June 24 and 25, 2014 to evaluate the soils exposed for foundation support. The findings of our observations and recommendations for the foundation design are presented in this report. We previously prepared a subsoil study for preliminary design of foundations at the site and presented our findings in a report dated April 18, 2014, Job No. I 14 086A. The observation of the Lot 3 building excavation was perfonned as additional services to our proposal for geotechnical services to Elk Meadows Development dated March 24, 2014. The proposed residence will be similar to that described in our previous report and be a two-story wood frame structure above a walkout lower level with a slab-on-grade ground floor. Spread footings placed on the natural soils and sized for an allowable bearing pressure of 1,500 psfwere designed for the building foundation support. At the time of our June 24 site visit, the foundation excavation was underway and about half complete with very sandy silty clay soils exposed in the northern and eastern portions. On June 25, the foundation excavation was essentially complete and had been cut in multiple levels from about 2 to 12 feet below the adjacent ground surface. The steps in grade between the levels ranged from about Yi to 4 feet. The soils exposed in the bottom of the excavation consisted of medium stiff to stiff, sandy to very sandy silty clay. Results of swell-consolidation testing performed on samples taken from the site, shown on Figures I and 2, indicate the soils are moderately compressible under conditions of loading and wetting with a nil to low hydro-compression potential. No free water was encountered in the excavation and the soils were generally moist. The soil conditions exposed in the excavation are consistent with those previously encountered on the site and suitable for support of spread footings designed for the .. Elk Meadows Development, LLC June 30, 2014 Page 2 recommended allowable bearing pressure of 1,500 psf with some risk of settlement due primarily to the compressible nature of the soils. Loose and disturbed soils should be removed in the footing areas to expose the undisturbed natural soils and the subgrade compacted. Other recommendations presented 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 limited 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, HEPWORTH-P i ' - David A. Young, P.E.\~21~.j ' -/-Ii ~ DAY /ksw ~~ ~" ~,,,,.. .... ,, attachments Figures 1 and 2, Swell-Consolidation Test Results Joh No. l 14 086A Moisture Content = 15.9 percent Dry Density = 106 pcf Sample ot Sandy Silty Clay From: Lot 3, Bottom of North-Central Portion of Excavation, 6/24/14. 0 r----r--r--I'---'-r-. l~ -........, 1 ... , -'I~ \ Compression '#. ~ j upon -wetting z 2 0 '\ \ 1/ w Cl) I\ w 3 r.... a: Cl. ) r-..LI :a: 0 ' (.) 4 \ \ 5 \ I) 6 ,. 0.1 1.0 10 100 APPLIED PRESSURE ( ksf) 114 086A ~ech SWELL-CONSOLIDATION TEST RESULTS FIGURE 1 HEPWORTH.PAWLAK GEOTECHNICAL Moisture Content = 12.9 percent Dry Density = 112 pcf -200 = 53 percent Sample of: Very Sandy Silty Clay From: Lot 3, Bottom of South-Central Portion of Excavation 6/25/14. 0 r---_ --:-._ r-1 ---1~ ~\ Compression (fl. / upon -o., wetting z 2 0 ~~ ,, (j) /v (/) ..__ v w 0: 3 D.. \ ~ 0 \ 0 4 " I\) 5 0.1 1.0 10 100 APPLIED PRESSURE ( ksf) 114 086A ~ SWELL-CONSOLIDATION TEST RESULTS FIGURE 2 HEPWORTl+PAWLAK GEOTECHNICAL.