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HomeMy WebLinkAboutB14-0302 HP Geotech letter.pdfOctober 27, 2014 Vail Custom Builders Attn: Benno Scheidigger P. 0. Box 2809 Edwards, Colorado 81632 ! ) [ . ~ • ! ' I ~ ; \ :' ', , . \ l i, t ! ..., 1 \ } ! '. \ I, \ ) i ' Job No. 114 13 IA Subject: Observation of Excavation, Proposed Residence, Lot 13, Block B, Vail Ridge Subdivision, 2722 Cortina Lane, Vail, Colorado Dear Benno: As requested, a representative of Hepworth-Pawlak Geotechnical, Inc. observed the excavation at the subject site on October 22, 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 conducted a subsoil study for design of foundations at the site and presented our findings in a report dated May 30, 2014, Job No. 114 13 lA. The proposed construction is similar to that discussed in our previous report. Spread footings bearing on the natural soils designed for an allowable bearing pressure of 2,000 psf were recommended for foundation support with some risk of settlement. The cut for the uphill side of the excavation has been soil nailed with a permanent type wall system. At the time of our site visit, the foundation excavation which was essentially complete had been cut in generally four levels from about 1 to 12 feet below the adjacent ground surface. The soils exposed in the bottom of the excavation consisted primarily of medium dense, clayey to very clayey sand with gravel and cobbles. In the shallower cut areas in the downhill southern portion of the excavation, stiff, sandy clay with gravel was exposed at subgrade. Depth of the clay soils over the sand soils appeared to be up to about 2 feet depth over the sand soils. Results of swell-consolidation testing performed on samples taken from the site, shown on Figure 1, indicate the clay soils are slightly to moderately compressible under conditions of loading and wetting with a low hydro-compression potential. The sample may have been partly disturbed due to the rock content. No free water was encountered in the excavation and the soils were slightly moist to moist in the deeper cut areas. 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 ,> I Vail Custom Builders October 27, 2014 Page 2 recommended allowable bearing pressure of 2, 000 psf. The risk of settlement is due primarily to the variable bearing conditions. Loose and disturbed soils should be removed in the footing areas to expose the undisturbed natural soils and the subgrade moistened and compacted. The bearing soils should be protected from frost and concrete should not be placed on frozen soils. 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 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. If you have any questions or need further assistance, please call our office. Sincerely, cc: Vail Custom Builders -Ted Leach (ted(f:i'•vailcustorn.corn) ---------------------- Job No_ l 14 131A ~tech