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HomeMy WebLinkAboutObservation of Excavation 05.26.2023'( Kumar ni Associates, Inc. Geotechnical and Materials Engineers 5020 County Road 154 and Environmental Scientists Glenwood Springs, CO 81601 phone: (970) 945-7988 fax: (970) 945-8454 email: kaglenwood@kumarusa.com An Empi©ya® Owned Company www.kumarusa.com Office Locations: Denver (HQ), Parker, Colorado Springs, Fort Collins, Glenwood Springs, and Summit County, Colorado May 26, 2023 Dockers Construction, Attn: David Ockers 499 River Bend Way Glenwood Springs, Colorado 81601 david dockersconstruction.com Project No. 23-7-312 Subject: Observation of Excavation, Proposed Deck Addition, 206 River Vista, Lot 256, Block 3, Phase II, Filing 1,2 & 3, Ironbridge PUD, Garfield County, Colorado Dear David: As requested, the undersigned representative of Kumar & Associates observed the excavation at the subject site on May 26, 2023 to evaluate the soils exposed for foundation support. The findings of our observations and recommendations for the foundation support are presented in this report. The services were performed in accordance with our agreement for professional engineering services to Dockers Construction dated May 26, 2023. The proposed deck is located at the northwest corner of the house and will be supported on two new footing pads. We understand that the new footings were designed for an allowable soil bearing pressure of 1,500 psf. At the time of our visit to the site, the two new foundation pad excavations had been cut in one level about 3 feet below the adjacent ground surface. The soils exposed in the bottom of the excavation consisted of silty sandy gravel with cobbles and scattered small boulders. The soils were placed as structural fill for support of residences as part of the original development of this area of Iron Bridge. No free water was encountered in the excavation and the soils were slightly moist. Considering the conditions exposed in the excavation and the nature of the proposed construction, spread footings placed on the existing structural fill soil designed for an allowable soil bearing pressure of 1,500 psf can be used for support of the proposed deck addition. The Dockers Const. May 26, 2023 Page 2 footing pads were formed and will be 2 feet square. Exterior footings should be provided with adequate soil cover above their bearing elevations for frost protection. Backfill placed around the footings and sonotube formed deck supports can consist of the on-site soils compacted to at least 90% of standard Proctor density at a moisture content near optimum. Backfill placed around the sonotube formed deck supports should be compacted and the surface graded to prevent ponding within at least 5 feet of the building. The recommendations submitted in this letter are based on our observation of the soils exposed within the foundation excavation and do not include subsurface exploration to evaluate the subsurface conditions within the loaded depth of foundation influence. This study is based on the assumption that soils beneath the footings have equal or better support than those exposed. The risk of foundation movement may be greater than indicated in this report because of possible variations in the subsurface conditions. In order to reveal the nature and extent of variations in the subsurface conditions below the excavation, drilling would be required. It is possible the data obtained by subsurface exploration could change the 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, Kumar & Associates. Inc. u Daniel E. Hardin, P.E.; DEH/kac Kumar & Associates, Inc. FA 24443 ` '* ( OF\ Project No. 23-7-312