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HomeMy WebLinkAboutB14-0429_SOILS REPORT_1413999480.pdfSOIL AND FOUNDATION INVESTIGATION FOR PROPOSED RESIDENCE LOT 1, BLOCK 1, VAIL VALLEY 1st FILING 1183 CABIN CIRCLE TOWN OF VAIL EAGLE COUNTY, COLORADO PROJECT NO. 14-2968 OCTOBER 1, 2014 PREPARED FOR: MR. SCOTT S. TURNIPSEED AIA P.O. BOX 3388 EAGLE, COLORADO 81631 P.O. Box 2837, Edwards, CO 81632 Tel (970) 926-9088, www.lkpengineering.com TABLE OF CONTENTS EXECUTIVE SUMMARY. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 SCOPE OF STUDY.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 SITE DESCRIPTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 PROPOSED CONSTRUCTION.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 FIELD INVESTIGATION.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 SUBSURFACE SOIL AND GROUNDWATER CONDITION.. . . . . . . . . . . . . . . . . . . . . . . . . 3 FOUNDATION RECOMMENDATIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 SLAB CONSTRUCTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 RETAINING WALLS.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 UNDERDRAIN SYSTEM. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 SITE GRADING AND DRAINAGE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 LAWN IRRIGATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 LIMITATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 FIGURES LOCATION SKETCH . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . .DRAWING NO. 1 SUBSURFACE EXPLORATION LOGS. . . . . . . . . . . . . . . . . . . . . . . . . . FIGURE NO’S 1-2 SWELL/CONSOLIDATION TEST RESULTS. . . . . . . . . . . . . . . . . . . . . . FIGURE NO’S 3-5 PERIMETER DRAIN . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . FIGURE NO. 6 P.O. Box 2837, Edwards, CO 81632 Tel (970) 926-9088, www.lkpengineering.com 2 EXECUTIVE SUMMARY The proposed residence should be supported with conventional type spread footings, designed for an allowable soil bearing pressure of 1000 psf. They should construct the footings on the undisturbed, silty sand. SCOPE OF STUDY This report presents the results of a subsurface Soil and Foundation Investigation for a proposed residence to be constructed on Lot 1, Block 1, Vail Valley, 1st Filing, 1183 Cabin Circle, Town of Vail, Eagle County, Colorado. The purpose of the subsurface soil and foundation investigation was to determine the engineering characteristics of the foundation soil and to provide recommendations for the foundation design, grading, and drainage. Geologic Hazard studies are outside of our scope of services. SITE DESCRIPTION Lot 1 is a 0.72-acres lot, at 1183 Cabin Circle, Town of Vail, Eagle County, Colorado. The topography is moderate for about the south 120 feet and then steep to the north, toward the Vail Golf Course. Drainage is to the north, northwest, and east. Vegetation on the lot consisted of landscaped grass, wild grass, pine and aspen trees. The lot has an existing two-story residence LKP Engineering, Inc. 3 with a walkout basement that will be torn down. To the southeast and west of the lot are existing residences. PROPOSED CONSTRUCTION The proposed residence will consist of two to three stories, wood frame construction, on a concrete foundation, with a basement, stepping into the lot. Loads are anticipated to be light, typical of residential construction. If the finalized plans differ significantly from the above understanding, they should notify us to reevaluate the recommendations of this report. FIELD INVESTIGATION The field investigation conducted on September 24, 2014, consisted of drilling, logging and sampling two test bores. The test bore locations are shown on Drawing No. 1. Drilling of the test borings was done with a 4-inch diameter, a continuous flight power auger on a truck mounted, drill rig. Soil samples for laboratory soil analysis and observation were taken at selected intervals with a California and Split Spoon Samplers, advanced with a 140-pound hammer, falling 30 inches. We show the soil profiles of the test borings on the Subsurface Exploration Logs, Figure No’s one and two. Soil samples for laboratory soil analysis and observation were taken at selected intervals. SUBSURFACE SOIL AND GROUNDWATER CONDITION The soil profiles encountered in the test borings were somewhat uniform. Test Boring No. 1 had about one foot of topsoil over light brown sandy gravel to gravelly sand with scattered LKP Engineering, Inc. 4 cobbles and boulders to about 5 feet, underlain by reddish brown silty sand to the maximum depth explored of 20 feet. Test Boring No. 2 had about one foot of topsoil over light to reddish brown, gravelly sand with scattered cobbles to the maximum depth explored of 20 feet. Ground water was not encountered. Geologic hazard studies are outside of our scope of services. FOUNDATION RECOMMENDATIONS The proposed residence should be supported with conventional type spread footings, designed for a maximum allowable soil bearing pressure of 1000 psf. The footings, for the entire foundation, should be placed on the undisturbed, silty sand to gravelly sand with scattered cobbles. Ground water was not encountered in either boring. We recommend minimum width of 16 inches for the continuous footings and 2 feet for the isolated footing pads. Continuous foundation walls should be reinforced top and bottom to span an unsupported length of at least 10 feet. A minimum of 48 inches of backfill cover is recommended for frost protection of the footing subsoils. The undersigned engineer should observe the foundation excavation to verify that the soil conditions are uniform throughout the foundation excavation or to provide additional recommendations as necessary. The foundation excavation should be free from excavation spoils, frost, organics and standing water. The on-site soil free from topsoil, organics, and rock fragments smaller than six inches, is suitable backfill material. Imported fill material, approved by the undersigned engineer, might be necessary for the foundation backfill. Voids left in the excavation, due to rock removal, should be filled with lean concrete. Footings should be constructed on a level surface. LKP Engineering, Inc. 5 SLAB CONSTRUCTION The natural on-site soils, exclusive of topsoil, organics, are suitable to support lightly loaded slab-on-grade construction. The subgrade for the slab-on-grade construction should be proof compacted to detect and remove soft spots. They should backfill overexcavated soft spots and other underslab fill with the on-site soil, free from topsoil and organics, or other suitable material, compacted to a minimum of 95 percent of the maximum standard Proctor density (ASTM D-698). Suitable material should be free from topsoil, organics and rock fragments greater than 3 inches. The concrete slab should be constructed over a 4-inch layer of clean gravel consisting of - 3/4 inch gravel with at least 50% retained on the No. 4 sieve and less than 3 percent passing the No. 200 sieve. They should reinforce the concrete slab-on-grade and score control joints according to the American Concrete Institute requirements and per the recommendations of the designer to reduce damage due to shrinkage. The concrete slab should be separated from the foundation walls and columns with expansion joints to allow for independent movement without causing damage. RETAINING WALLS They should design foundation walls retaining earth and retaining structures that are laterally supported to resist an equivalent fluid density of 60 pcf for an “at-rest” condition. Laterally unrestrained structures retaining the on-site earth should be designed to resist an equivalent fluid density of 40 pcf for the “active” case. Passive earth pressure of 350 psf can be used for the lateral pressure against the sides of the footings. Resistance to sliding at the bottom of the footings can be calculated based on a coefficient of friction of 0.5. Undisturbed soil or a structural fill compacted to 100 percent of the maximum dry density and within 2 percent of the optimum moisture content will be used to resist lateral loads at the sides of the footings. LKP Engineering, Inc. 6 The above design recommendations assume drained backfill conditions and a horizontal backfill surface. Surcharge loading due to adjacent structures, weight of temporary stored construction materials and equipment, inclined backfill and hydrostatic pressure due to undrained backfill should be incorporated in the design. They should try to prevent the buildup of hydrostatic pressure behind the retaining wall. UNDERDRAIN SYSTEM To reduce the risk of surface water infiltrating the foundation subsoil (and the development of a perched water condition) installation of a foundation perimeter drain is highly recommended. The foundation perimeter drain should consist of a 4-inch diameter perforated pipe sloped to a suitable gravity outlet, or to a sump pump location. The drain should slope at 1/4 inch per foot if flexible or at 1/8 of an inch if rigid pipe is used. The bottom of the trench adjacent to the footing should be lined with a polyethylene moisture barrier glued to the foundation wall. The drain pipe should be placed over the moisture barrier and covered with a minimum of 6 inches of -3/4 inch free-draining granular material. Geotextile (Mirafi 140N or equivalent) should be used to cover the free-draining gravel to prevent siltation and clogging of the drain. The backfill above the drain should be granular material to within 2 feet of the ground surface to prevent a buildup of hydrostatic pressure. The top one foot of the backfill material should consist of a relatively impervious fill. The backfill should slope away from the building. SITE GRADING AND DRAINAGE The site surrounding the building structure 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 LKP Engineering, Inc. 7 should be covered with a minimum of 1 foot of relatively impervious fill to reduce the potential of surface water infiltrating the foundation subsoils. Surface water naturally draining toward the proposed building site or permanent cuts, should be diverted around and away from it by means of drainage swales or other approved methods. The roof drains and downspouts should extend and discharge beyond the limits of the backfill. Exterior backfill should be compacted at or near the optimum moisture content to at least 95% of the maximum standard Proctor density under pavement, sidewalk and patio areas and to at least 90% of the maximum standard Proctor density under landscaped areas. Mechanical methods of compaction should be used. Do not puddle the foundation excavation. Permanent, unretained cut and fill slopes should be graded at two horizontal to one vertical or flatter with slope heights not exceeding 10 feet. Slopes exceeding 10 feet should have benching incorporated. To protect the newly created slopes, erosion control methods should be used. If water seepage is encountered during the slope construction, additional studies will be required to evaluate the slope stability. LAWN IRRIGATION It is not recommended to introduce excess water to the foundation soils by installing sprinkler systems next to the building. The installation of the sprinkler heads should insure that the spray from the heads will not fall within 10 feet of foundation walls, porches or patio slabs. Lawn irrigation must be controlled. LIMITATION This report has been prepared according to locally accepted Professional Geotechnical Engineering standards for similar methods of testing and soil conditions at this time. There is no LKP Engineering, Inc. 8 other warranty either expressed or implied. The findings and recommendations of this report are based on field exploration, laboratory testing of samples obtained at the specific locations shown on the Location Sketch, Drawing No.1 and on assumptions stated in the report. Soil conditions at other locations may vary, which may not become evident until the foundation excavation is completed. If soil or water conditions seem different from those described in this report we should be contacted immediately to reevaluate the recommendations of this report. This report has been prepared for the exclusive use of Scott S. Turnipseed, AIA, for the specific application to the proposed residence on Lot 1, Block 1, Vail Valley, 1st Filing, 1183 Cabin Circle, Town of Vail, Eagle County, Colorado. Sincerely, LKP ENGINEERING, INC. ________________________ Luiza Petrovska, PE President \\SERVER\Shared\_WP X4-LKP\_2014\14-2968sltgrsnd-bor.RPT.wpd LKP Engineering, Inc.