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HomeMy WebLinkAboutObservation of ExcavationH~ ~tech HEPWORTH· PAWLAI< GEOTECHNICAL July 15, 2013 Kevin Milner P .O. Box 302 Glenwood Springs, Colorado 81602 Q~m::e l l-l<lt 1!:!mail. com '. It .I I . ' I I ' I I ' I· Job No. 112 386A Subject: Observation of Excavation, Proposed Garage, Lot 14, Homestead Estates, 2878 Homestead Road, Garfield County, Colorado Dear Kevin: As requested, a representative of Hepworth-Pawlak Geotechnical, Inc. observed the excavation at the subject site on July 9, 2013 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 November 30, 2012, Job No. 112 386A. At the time of our visit to the site, the foundation excavation had been cut in one level from Yz to 2 feet below the adjacent ground surface. The soils exposed in the bottom of the excavation consisted of slightly sandy clay and gravel with cobbles. A 1 foot deep hole below foundation grade was observed on the north side of the structure. We recommended at the site that holes below thickened edge foundation grade due to boulder removal be backfilled with the on-site soils moistened and well compacted to 98% of the maximum standard Proctor density at a moisture content near optimum No free water was encountered in the excavation and the soils were slightly moist. The soil conditions exposed in the excavation are consistent with those previously encountered on the site and suitable for support of a thickened edge slab foundation designed for the recommended allowable bearing pressure of 2,000 psf Loose and disturbed soils should be removed in the footing areas to expose the undisturbed natural soils. The thickened edge slab should be insulated for frost protection in accordance with the 2009 International Residential Code. 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 Kev in Milner July 15, 2013 Page 2 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 condit ions for possible changes to recommendations contained in this letter. Our services do not include detennining 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 quest ions or need further assistance, please call our office. S incerely, HEPWORTH -PAWLAK GEOTCIINICAL, INC. Jo b No. 112 386A