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HomeMy WebLinkAboutObservation of Excavation 07.24.2018PKUMAR Geotechnical Engineering I Engineering Geology Materials Testing 1 Environmental 5020 County Road 154 Glenwood Springs, CO 81601 Phone: (970) 945-7988 Fax: (970) 945.8454 Email: hpkglenwood@kumarusa.com Office Locations: Denver (HQ), Parker, Colorado Springs, Fort Collins, Glenwood Springs, Summit County, Colorado July 24, 2018 Todd Bryan 45 Oak Court Parachute, Colorado 81635 Todd. bryan66 C gniai l.com Project No. 18-7-112.01 Subject: Observation of Excavation, Proposed Residence, Lot 12, Monument Ridge, 100 Dry Creek Road 331, Battlement Mesa, Garfield County, Colorado Dear Todd: As requested by Rex Smith, a representative of H-P/Kumar observed the excavation at the subject site on July 3, 2018 to evaluate the soils exposed for foundation support. The findings of our observations and recommendations are presented in this report. The services are supplemental to our agreement for professional services to you dated January 16, 2018. We previously conducted a subsoil study for design of foundations at the site and presented our findings in a report dated February 6, 2018, Project No. 18-7-112. The proposed construction is similar to that discussed in the previous report. Spread footings bearing on the natural soils designed for an allowable bearing pressure of 1,500 psf were recommended for foundation support, with some risk of movement. At the time of our site visit, the foundation excavation had been cut in one level from about 2 to 51/2 feet below the adjacent ground surface. The soils exposed in the bottom of the excavation consisted of stiff, sandy clay and silt. The excavation subgrade had been moistened and compacted. Results of swell -consolidation testing performed on a sample taken from the site, shown on Figure 1, indicate the soils are moderately to highly compressible under conditions of loading and wetting with a moderate collapse potential when wetted under a constant 1,000 psf surcharge. The sample was likely partly disturbed during the sampling process, however, the near surface soils in the area of the subject site typically do have a hydro -compression potential. No free water was encountered in the excavation and the soils were slightly moist. The soil conditions exposed in the excavation are generally consistent with those previously encountered on the site and suitable for support of spread footings designed for the recommended allowable bearing pressure of 1,500 psf. The risk of settlement is primarily if the bearing soils were to become wetted and precautions should be taken to prevent wetting. Prior to Todd Bryan July 24, 2018 Page 2 the footing construction, all loose disturbed soils should be removed and the subgrade re - compacted as needed. 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, H -P KU MAR pad Robert L. Duran, E. I. Reviewed by o- ..., - 6w • G) S i; 32-216 David A Young, P. i;e c�, 7- Z571 y� �+ RLD/kac "me0?°ONA1. , attachments Figure 1 — Swell-tonsolidation Test Results cc Cornerstone Builders — Rex Smith (rex.smith7@aol.com) Garfield County Building Dept. — Jim Wilson (iwilson@garfetd-couiity.com) Project No. 18-7-112.01