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HomeMy WebLinkAboutB15-0302 Soils Report.pdf~ Engineering, Inc. ~ CMUGEOTECHNICAL September 28, 2015 c/o Mark and Constance Miller Michael Johnson Cadillac Construction P.O. Box 3556 Vail, CO 81658 Email: cadillac@vail.net Dear Michael: RE: Open Hole Observation, Followup Visits - Miller Addition Parcel 13, Eiger Chalets, Phase II 1370 Sandstone Dive #13 Vail, Eagle County, Colorado Project No. 15-3058 At your request, today, September 28, 2015, at about 9:00 and 10:40 a.m., we visited the construction site for the Miller Addition, Parcel 13, Eiger Chalets, Phase II, 1370 Sandstone Dive # 13, Vail, Eagle County, Colorado. The purpose of our followup site visits was to observe the three east holes for the footing support of the addition, and to verify that they have been excavated through the fill and topsoil material (observed during the previous site visits) and into the underlying, firm, native soil. The holes were overexcavated and in the excavation for the southeast pad, the bottom of footing of the existing building was exposed. The total depth was measured to be about 11 feet below the existing grade and about 8 feet below the deck pads. The soil exposed in the foundation excavation for the proposed addition is suitable for the assumed soil bearing pressure of 1500 psf Soft spots were not reported. This report has been prepared according to locally accepted Professional Geotechnical Engineering standards for similar methods of testing and soil conditions at this time. The findings and recommendation stated above are based on the soil conditions observed and tested in the foundation excavation only. There is no other warranty either expressed or implied. If you have any questions, please do not hesitate to call. Sincerely, LKP Engineering, Inc. Luiza Petrovska, PE J:\_ WP X4-LKP\_2015\15-3058open-add2.wpd P.O. Box 2837, Edwards, CO 81632 Tel (970) 926-9088, www.lkpengineering.com ~ Engineering, Inc. ~ CIVIUGEOTECHNICAL September 20, 2015 c/o Mark and Constance Miller Michael Johnson Cadillac Construction P.O. Box 3556 Vail, CO 81658 Email: cadillac@vail.net Dear Michael: RE: Open Hole Observation -Miller Addition Parcel 13, Eiger Chalets, Phase II 1370 Sandstone Dive #13 Vail, Eagle County, Colorado Project No. 15-3058 At your request, on September 17, 2015, we visited the construction site for the Miller Addition, Parcel 13, Eiger Chalets, Phase II, 1370 Sandstone Dive #13, Vail, Eagle County, Colorado. The purpose of our site visit was to observe and/or test the soils exposed in the foundation excavation for the proposed addition in order to verify the design bearing capacity of 1500 psf, as shown on the structural drawings by Monroe and Newell, Inc., dated July 21, 2015. The excavation for the proposed addition was on the west side of the unit, the second to the last, on the north side of the 8-unit building. It consisted of holes for six footing pads. In each of the holes were concrete forms for the pads and rebar for the pads and columns. We understand that the three east pads are designated for the building addition and the west three are for the proposed deck. The soil in the excavation of the three west pads, consisted of undisturbed, sandy gravel and sandy, gravelly clay with cobbles and boulders A soil sample of the undisturbed soil exposed in the west pads was taken and was tested for natural moisture content and grain size distribution. The test results are appended to this report. Unsuitable, old bakfill material was encountered in the area of the east three pads, adjacent to the existing building. The old backfill material consisted of topsoil, organics, large boulders, sand and gravel, all mixed together. Michael told us that the bottom of footing elevation of the existing building is another 10 feet below the bottom of the excavation and they can't excavate to undisturbed soil at the bottom of the existing foundation. In order to span over the unsuitable, old badifill material, we recommend that, the proposed new foundation consist of pads and grade beams, where the pads will be constructed on the undisturbed, sandy gravel and sandy, gravelly clay with cobbles and boulders, and the grade beams will be spanning the rest of the distance, and be doweled into the existing foundation. Consult with your structural engineer for the modification of the foundation design. Helical piers are not recommended due to the large amount of boulders, as observed in the P.O. Box 724, Eagle, CO 81632 Tel (970) 926-9088 Miller Residence Addition Page 2 of2 Project No. 15-3058 September 20, 2015 stockpile of boulders, and in the old backfill. For a foundation supported with micro piles, or other, deep type of a foundation support, additional soil testing with a drill rig will be required. The soil exposed in the west three pad holes of the foundation excavation for the proposed addition is suitable for the assumed soil bearing pressure of 1500 psf. Soft spots were not reported. The site surrounding the addition should slope away from the building in all directions. A minimum of 12 inches in the first 10 feet is recommended in unpaved areas, and three inches in the first 10 feet in paved areas. The top of the granular foundation backfill should be covered with a minimum of 1 foot of relatively impervious fill to reduce the potential of surface water infiltrating the foundation subsoils. This report has been prepared according to locally accepted Professional Geotechnical Engineering standards for similar methods of testing and soil conditions at this time. The findings and recommendation stated above are based on the soil conditions observed and tested in the foundation excavation only. There is no other warranty either expressed or implied. If you have any questions, please do not hesitate to call. Sincerely, LKP Engineering, Inc. Luiza Petrovska, PE J:\_ WP X4-LKP\_2015\l5-3058open-add.wpd LKP Engineering, Inc.