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Home My WebLink AboutB10-0158 SPECIAL INSPECTIONS0 G( tech HEPWORTH - PAWLAK GEOTECHNICAL Man August 24, 2010 JB Builders Attn: John Barry 310-01 0 1 5 8 5 ' "� 01.7 �� I ,cpworth- Pawlak Geotechnical, Inc. 1020 County Road 154 Glenwood Springs, Colorado ](101 Phone: Q70- 94i-79ti8 Fax: 970-04 - .4 - 4 i4 entail: hE�e�;�il��•e�.�Cich.cnnt o [E (IM EUWE SEA' 2 2010 P.O. Box 3233 TOWN OF VAIL Avon, Colorado 81620 Job No. 110 228A Subject: Observation of Excavation, Proposed Addition, - Lot 2, Block E, Vail Das Shone, Filing 1, 2606 Davos Trail, Vail, Colorado Dear Mr. Barry: C J As requested, a representative of Hepworth - Pawlak Geotechnical, Inc. observed the excavation at the subject site on August 13, 2010 to evaluate the soils exposed for foundation support. The findings of our observations and recommendations for the foundation design are presented in this report. The services were performed in accordance with our agreement for professional engineering services to JB Builders, dated July 21, 2010. The proposed addition will be one story wood frame construction above a partial crawlspace and partially slab -on- grade. The addition will be located on the west side of the residence. The existing residence is two story wood frame construction above a walkout level: At the time of our visit to the site, the addition excavation was nearly completed and had been cut in one level from 4 to 9 feet below the adjacent ground surface. Three footing pad excavations had been cut separate just south of the main excavation. The soils exposed in the bottom of the excavation consisted of slightly gravelly sandy clay. Results of swell - consolidation testing performed on samples taken from the site, shown on Figure 1, indicate the soils are slightly compressible under conditions of light loading and wetting. The samples showed slight to moderate compressibility under additional loading after wetting. No free water was encountered in the excavation and the soils were slightly moist to moist. The bottom of the footing of the residence was exposed along the east side of the excavation. Considering the conditions exposed in the excavation and the nature of the proposed construction, spread footings placed on the undisturbed natural soil designed for an allowable soil bearing pressure of 2,000 psf should be adequate for support of the proposed addition. The exposed soils tend to compress when wetted and there could be some post - construction settlement of the foundation if the bearing soils become wet. • Footings should be a minimum width of 16 inches for continuous walls and 2 feet for Parker 303-841- • Colorado S prings 719 - 633 -5;62 ♦ Silverdwo Q i0- 6,-, -1 QS9 -- l..lu11u%11 August 24, 2010 Page 2 columns. Loose disturbed soils and any existing fill in footing areas should be removed and the bearing level extended down to the undisturbed natural soils. Exterior footings should be provided with adequate soil cover above their bearing elevations for frost protection. Continuous foundation walls should be reinforced top and bottom to span local anomalies such as by assuming an unsupported length of at least 12 feet. Foundation walls acting as retaining structures should also be designed to resist a lateral earth pressure based on an equivalent fluid unit weight of at least 55 pcf for on -site soil as backfill. A perimeter foundation drain should be provided to prevent temporary buildup of hydrostatic pressure behind the crawlspace walls and prevent wetting of the lower level. Structural fill placed within floor slab areas can consist of the on -site soils compacted to at least 95% of standard Proctor density at a moisture content near optimum. Backfill placed around the structure should be' compacted and the surface graded to prevent ponding within at least 10 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, HEP I A OTECHNICAL, INC. Louis E. Eller Reviewed by: L, p q 7'�� Steven L. Pawlak P 1 6222 * 8r LEE /ksw e •� 'D�k�. �e attachment Figure 1 — F ation Test Results cc: Monroe & Newell Engineers — Attn: Craig Carroll JVU 1 11V LUSH GfC f ec 1 I It 0 No movement upon wetting Density = 90 pcf Sample of: Sandy Clay From: Bottom of Excavation at South Side, East Pad Moisture Content = 8.2 percent Dry 0 Compression upon wetting 1 0 2 C_ 0 2 3 a E 0 U 4 5 6 0.1 1.0 10 100 APPLIED PRESSURE - ksf 0 C 0 � 1 a E 0 U 2 0.1 1.0 10 100 APPLIED PRESSURE - ksf H 110 228A SWELL- CONSOLIDATION TEST RESULTS Figure 1 HEPWORTH•PAW LAK GEOTECHNICAL 0 No movement upon wetting Density = 90 pcf Sample of: Sandy Clay From: Bottom of Excavation at South Side, East Pad Compression upon wetting 0 No movement upon wetting Moisture Content = 12.5 percent Dry Density = 107 pcf Sample of: Sandy Clay From: Bottom of Excavation at Center of West Wall �� 0 HEPWORTH - PAWLAK GEOTECHNICAL CONSTRUCTION ACTIVITY REPORT 5020 County Road 154 Glenwood Springs, CO 8160 Phone: 970 - 945 -7988 Fax: 970 - 945 -8454 hpgeo @hpgeotech.com Client: JB Builders Job No.: 110 228A Day: Monday John Barry Date: 8116/10 P.O. Box 3233 Page: 1 of 1 Avon, Colorado 81620 Project: Proposed Addition, Lot 2, Block E, Vail Das Shone, Filing 6a368.Davos Trail, Vail, Colorado Weather: Cloudy, light breeze, light rain Temperature: 65 °F at 1:00 pm - Contractor's Construction Activities: Forming and reinforcing steel installation was in progress for addition on west side of building. Footing dowels were installed into the existing foundation. Equipment in Use: Concrete drill, air compressor, epoxy caulk gun HP Geotech's Site Activities: As requested, we observed the dowel installation. Two dowel holes were drilled 6 inches deep at each of three footing lines, cleaned with compressed air, epoxied, and then #4 by 3'6" dowels were installed 6 inches into the existing foundation. Installation was observed to be in compliance with Kirkham Architects Drawing S2.1 dated 6/25/10. Verbal Communication: distribution: 0WIE SEE 21 M10 TOWN OF VAIL JB was informed of our observations Thomas J. Westhoff, CET Steven L. Pawlak, P.E. Field Technician Reviewed By /ksw G ovow* oV&ech HEPWORTH - PAWLAK GEOTECHNICAL Joe Bened CONSTRUCTION ACTIVITY REPORT Client: JB Builders Job No.: 110 228A Day: Monday John Barry Date: 8/23/10 P.O. Box 3233 Page: 1 of 1 Avon, Colorado 81620 .2GOlo Project: Proposed Addition, Lot 2, Block E, Vail Das Shone, Filing 6,2" Davos Trail, Vail, Colorado Weather: Partly Cloudy Temperature: 75 °F at 12:30 pm Contractor's Construction Activities: L -hook dowels Equipment in Use: HP Geotech's Site Activities: As requested we visited the site to observe dowel installation in the walls. Verbal Communication: JB & Foundation foreman were advised that the dowel installation was adequate. distribution: /ksw p�C U T LE SEP 2 `1 TOWN OF VAIL 5020 County Road 154 Glenwood Springs, CO 8160 Phone: 970- 945 -7988 Fax: 970 - 945 -8454 hpgeo @hpgeotech.com Steven L. Pawlak, P.E. Field Technician Reviewed By