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HomeMy WebLinkAboutB15-0213_B15-0213 HP Geotech report_1441922580.pdf~ech HEPWORTH-PAWLAK GEOTECHNICAL August 26, 2015 John and Judy Collis P.O. Box 3363 Hamilton HM PX Bermuda judycollis@jexec.bm johncollis@jexec.bm P.rn Li\.. Gc«tc·dmiul, Inc C·wir1Eo.1ci154 !;ax 97l' 941 1'.J 54 c·nclll: ~©~~w~rn • SEP l 0 2015 ... ,~1 lJ TOWN OF VAIL Job No. 115 146A Subject: Observation of Excavation, Proposed Addition, Lot 6, Vail Village West, Filing 2, 1755 West Gore Creek Drive, Vail, Colorado Dear Mr. and Mrs. Collis: As requested, a representative of Hepworth-Pawlak Geotechnical, Inc. observed the excavation at the subject site on August 21, 2015 to evaluate the soils exposed for foundation support. The findings of our observations and recommendations for the foundation design are presented in this report. We previously conducted a subsoil study for design of foundations at the site and presented our findings in a report dated May 27, 2015, Job No. 115 146A. The current site observation was conducted in addition to and in accordance with our agreement for professional engineering services with you dated April 13, 2015. The proposed addition is essentially the same as described in our previous report and will be attached to the east side of the existing residence. Spread footings placed on the natural soils and sized for an allowable bearing pressure of 2,000 psf were recommended for the addition foundation support. At the time of our visit to the site, the foundation excavation had been cut in three levels from 4 to 6 feet below the adjacent ground surface. The steps in grade between levels were about 2 to 5 feet down to the north and footings of the existing residence were exposed at the downhill west side of the excavation. The soils exposed in the bottom of the excavation consisted of silty sand and gravel with cobbles. The bottom of excavation had been compacted in footing areas. The results of a gradation analysis performed on a sample of the natural granular soils (minus 5 inch fraction) obtained from the site are presented on Figure 1. No free water was encountered in the excavation and the soils were slightly moist to moist. The soil conditions exposed in the excavation are consistent with those previously encountered on the site and suitable for support of spread footings designed for the recommended allowable bearing pressure of 2,000 psf. Loose and disturbed soils should be removed in the footing areas to expose the undisturbed natural soils. Other recommendations presented in our previous report which are applicable should also be observed. John and Judy Collis August 26, 2015 Page 2 The recommendations submitted in this letter are based on our observation of the soils exposed within the foundation excavation and the previous limited 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. 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, SLP/ksw Attachment: cc: RA Nelson and Associates -Ryan La Vire (rlavire@ranelson.com) Job No. 115 146A El z ~ w a::: ~ z w CJ a::: w a.. I HYDROMETERANALYSIS I SIEVEANALYS!S CLEAR SQUARE OPEN1NGS 7 HR TIME READINGS U.S. STANDARD SERIES I O ~~ ~~-15 MIN. 60MIN19MIN.4 MIN 1 MIN #200 #100 #50 #30 #16 #8 #4 3/8' 3/4' 11/2' 3• 5'6' 8' 100 10 20 30 40 50 60 70 80 90 100 001 002 005 009 019 DAYTOSl.T GRAVEL 50 % LIQUID LIMIT 037 074 150 300 600 118 2 36 4 75 DIAMETER DF PART'CLES IN MtWMETERS SAND 28 % 9.5 19.0 375 12.5 762 152 203 127 SILT AND CLAY 22 % % PLASTICllY INDEX % SAMPLE OF: Silty Sand and Gravel with Cobbles FROM: Bottom of Excavation 90 80 70 60 50 40 30 20 10 0 (.!) z v; (/) < a.. ~ z ~ a:: w a.. 115146A GRADATION TEST RESULTS Figure 1