HomeMy WebLinkAboutFoundation Recommendations 10.28.2020RECEIVED GARFIELD COUNTY COMMUNITY DEVELOPMENT Huddleston-Berry Engineering & Testing, LLC United Companies PO Box 3609 Grand Junction, Colorado 81502 Attention: Mr. Robert Lewis Subject: Foundation Recommendations New Batch Plant Rifle, Colorado Dear Mr. Lewis, 2789 Riverside Parkway Grand Junction, Colorado 81501 Phone: 970-255-8005 Info@huddlestonberry.com October 28, 2019 Project#00256-0079 At your request, Huddleston-Berry Engineering and Testing, LLC (HBET) prepared this letter regarding foundations for a new concrete batch plant proposed in Rifle, Colorado. Foundation drawings were prepared by Tim Hayashi of TH Engineering. HBET conducted a site visit on October 9, 2019. At the time of our site visit, HBET observed a large excavation in the vicinity of the proposed new batch plant. HBET understands that petroleum contamination was removed from this area of the site. The soil profile exposed in the excavation indicated that the soils at the site consist of sandy gravel and cobble (pit -run) soils. In addition, HBET understands that the excavation is proposed to be backfilled with 1/4-inch minus material from the adjacent gravel pit. In general, these materials will provide good structural support. However, in order to limit the potential for differential settlements due to the presence of thick fill under a portion of the new facility, HBET recommends placing a layer of pit -run or cobble/boulder sized materials in the bottom of the excavation to raise the subgrade above the groundwater level. At this elevation, a layer of geogrid consisting of Haynes RX1200 or Tensar TX5 is recommended. Above the geogrid, 1/4-inch minus material should be placed in maximum 10-inch loose lifts, moisture conditioned to within ±2% of optimum moisture content, and compacted to a minimum of 98% of the modified Proctor maximum dry density. The side slopes of the excavation should be benched, as necessary, to ensure that compacted materials are placed above level subgrades. In addition to the backfilling of the large excavation, HBET recommends that all other foundation areas of the new facility be constructed above a minimum of 24-inches of compacted 1/4-inch minus material. The structural fill should extend a minimum of 24-inches beyond the edges of the foundations. Rifle Plant #00256-0079 10/28/19 Huddleston-Bevy EnillilvcrloINI I For foundation building pad preparation as recommended, a maximum allowable bearing capacity of 2,000 psf may be used. In addition, a modulus of subgrade reaction of 200 pci may be used for structural fill consisting of 1/4-inch minus materials. Foundations subject to frost should be at least 36-inches below the finished grade. We are pleased to be of service to your project. Please contact us if you have any questions or comments regarding the contents of this letter. Respectfully Submitted: Huddleston-Berry Engineering and Testing, LLC Michael A. Berry, P.E. Vice President of Engineering Z:\2008 ALL PROJECTS\00256 - United Companies\00256-0079 Rifle Plant\200 - Geo\00256-0079 L102819 doc 2