The URL can be used to link to this page

Home My WebLink AboutObservation of Excavation 09.11.20190 1(+A&Kuniar Aswellatm be. 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 Employee Owned Company www.kumarasa.com Office Locations: Denver (HQ), Parker, Colorado Springs, Fort Collins, Glenwood Springs, and Summit County, Colorado September 11, 2019 Corey DePaolo 779 East 17r' Street Rifle, Colorado 81650 (cdepaolo67(c�gmail.com) Project No. 19-7-238 Subject: Observation of Excavation, Proposed Residence, 9616 Lazy K Road, South of Silt, Garfield County, Colorado Dear Corey: As requested, a representative of Kumar & Associates observed the excavation at the subject site on August 8, 2019 to evaluate the materials exposed for foundation support. We subsequently performed compaction testing on structural fill placed below the footing areas. The findings of our observation, test results and recommendations are presented in this report. The services are supplemental to our agreement for professional services to you dated April 16, 2019. We previously conducted a subsoil study for design of foundations at the site and presented our findings in a report dated May 21, 2019, Project No. 19-7-238. The proposed construction is similar to that discussed in our previous report. The building has been designed to be supported on spread footings bearing on 3 feet of imported structural fill and sized using an allowable soil bearing pressure of 2,000 psf, as recommended in the previous report. At the time of our August 8 site visit, the foundation excavation had been cut in two levels from about'/2 to 8 feet below the adjacent ground surface. The materials exposed in the bottom of the excavation consisted of stiff, sandy to very sandy silty clay in the shallower cut areas and medium hard, weathered claystone bedrock in the deeper cut areas to the west. Results of swell - consolidation testing performed on samples taken from the site, shown on Figure A-1, indicate the soils are moderately compressible under conditions of loading and wetting with a low hydro - compression potential, and that the weathered claystone possesses a moderate swell potential when wetted. No free water was encountered in the excavation and the soils and bedrock materials were slightly moist. Corey DePaolo September 11, 2019 Page 2 A 3 feet depth of minus 1'/ inch aggregate base course (CDOT Class 5 material) was then placed and compacted in the footing areas as structural fill below the footings. We returned to the site on August 20 to test compaction of the in -place fill. The results of the compaction testing are attached and indicate the fill was compacted to at least 98% standard Proctor density as recommended. Results of laboratory standard Proctor and standard properties testing on a sample of the base course is attached as Figures 1 and IA. The conditions exposed in the excavation are consistent with those previously encountered on the site and the structural fill adequately compacted, and suitable for support of spread footings designed for the recommended allowable bearing pressure of 2,000 psf. There is some risk of foundation movement if the soils or bedrock below the structural fill were to become wetted and precautions should be taken to prevent wetting. Prior to the footing construction any loose and disturbed structural fill should be recompacted as needed. Other recommendations presented in our previous report which are applicable should also be observed. The recommendations submitted in this letter are based on our observation of the soils exposed within the foundation excavation and the previous 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. If you have any questions or need further assistance, please call our office. Sincerely, Kumar & David A. Y DAY/ljf attachments Figure A-1, Swell -Consolidation Test Results Field Compaction Testing Report for August 20, 2019 Figures 1 and 1 A, Laboratory Standard Proctor Test Results cc: Garfield County Building Dept. — Jim Wilson (jwilsonggarfield-county.com) Kumar & Associates, Ina ,t, Project No.19-7-238 1 0 0 J J W N —1 I z 0 —2 a 0 J O 0 —3 z 0 U —4 —5 1 1.0 APPLIED PRESSURE — KSF 10 100 2 9 = v 1 3 J J _ 3 0 Ln 0 —1 Q _ 0 0 z —2 O n of i A 1.0 APPLIED PRESSURE — KSF 10 100 m 19-7-238 Kumar & Associates SWELL —CONSOLIDATION TEST RESULTS Fig.A-1 m% H> SAMPLE OF: Sandy Silty Clay with Gravel FROM: Bottom of NE Portion of Excavation WC = 7.9 %, DID= 103 pcf ADDITIONAL COMPRESSION UNDER CONSTANT PRESSURE DUE TO WETTING I i I I SAMPLE OF: Weathered Claystone FROM: Bottom of SW Portion of Excavation WC = 8.6 %, DD = 121 pcf EXPANSION UNDER PRESSURE UPON CONSTANT WETTING — — - - - - - - - i - Those test Ito apply only emplea tastedu The testing report shall not De reproduced, except full, without the written approval Kumar and Associates, Inc. Swell Consolidation feeling performed accordance with ASTM D-4546. to the In of in - - - 1(+AKumar ni AssociaieInc.® Geotechnical and Materials Engineers and Environmental Scientists 5020 County Road 154, Glenwood Springs, CO 81601 Phone: (970) 945-7988, Fax: (970) 945-8454 Email: kaglenwood(a)kumarusa.com Earthwork Compaction Testing Report Client: Corey DePaolo Project No.: 19-7-238 Day: 779 East 17th Street Date: Rifle, Colorado 81650 Page Tuesday 08-20-19 1 of 1 Project: Proposed Residence, 961 6 Lazy K Road, South of Silt, Garfield County, Colorado Weather: Clear, calm, dry Temperature: 880 at 12:30 pm Earthwork Contractor: I Equipment Used: Mini Track Floe, Compactor Description of Earthwork We performed compaction testing on in -place structural fill below footing areas Tested: at footing grade. Sample(s) Obtained: We obtained a sample of 1'/2" aggregate base course for laboratory Proctor analysis, see Figures 1 and 1A for lab test results. Verbal Communication: Corev DePaolo was informed of our field test results. Placement and Compaction Procedure: Not observed by Kumar Associates Lift Thickness: Max. Rock Size: 1'/2" Moisture Conditioning: Compactor(s) Used: Walk -Behind, Jumping Jack Number of Passes: Nuclear Gauge Moisture/Densit Test Results Test Location Depth or Field Dry Field Field Min. Proctor No. Elev. DensityMoisture Content Comp.Comp. Req. Lab No. Below Footing Structural Fill (pcf) % ° (/0) 1 Southwest corner Footing Grade 136.7 3.2 98 98 341-19 2 35' S of northwest corner Footing Grade 136.0 3.2 98 98 341-19 3 50' E of northwest corner Footing Grade 136.4 3.1 98 98 341-19 Proctor Samnle Reference: Lab No. Method Description Max. Dry Dens. cf Opt. Moist. % 341-19 ASTM D 698 1%" Aggregate Base Course 139.4 4.2 nlJ 1C 11 11-N I J V r11VIVIVJ NO M K -1VLI Vr VVK VDJ A I IVIVJVr TILL rL "mmIV I, VVC KHVG KGLIGU VIV IML VUNI MAU I UK I U I.VN I INUt NYYLT INU IKt KtLUMMtNUtU COMPACTIVE EFFORT AND MOISTURE TO FILL DURING THE TIMES WHEN OUR OBSERVER IS NOT OBSERVING OPERATIONS. THE NUCLEAR DENSOMETER METHOD OF TESTING WAS USED IN SUBSTANTIAL ACCORDANCE WITH ASTM D 6938. Distribution: Corey DePaolo (cdepaolo67(&gmail.com) /mj r Justin Orgill David A. Young, P.E. Field Technician Reviewed By Laboratory Proctor Compaction Test Report 147 142 0 137 U a C 132 ZAV for Sp.G. _ 2.50 127 122 2 3 4 5 6 7 8 Water content, % —� - Rock Corrected —o-- - Uncorrected Test specification: ASTM D 698-12 Method C Standard ASTM D4718-15 Oversize Corr. Applied to Each Test Point Elev/ Depth Classification Nat. Moist. Sp.G. LL PI % > 3/4 in. % < No.200 USCS AASHTO GP -GM A-1-a NV NP 25 7.5 ROCK CORRECTED TEST RESULTS UNCORRECTED MATERIAL DESCRIPTION Maximum dry density = 139.4 pcf Optimum moisture = 4.2 % 134.6 pcf 5.2 % 1.5" Aggregate Base Course Project No. 19-7-238 Client: Corey DePaolo Project: Six Lazy K Road, South of Silt, Garfield County, Colorado o Loc.: Northeast Corner of Project - Flag Sand & Gravel Sample No.: 341-19 Remarks: See Figure I for classification results. Figure 1 Kumar & Associates, Inc. Glenwood Springs, Colorado Tested By: KO Checked By: MINE I 111 � GRAIN SIZE - % +3„ % Gravel % Sand Coarse Fine Coarse Medium 0 25 32 9 12 SIEVE SIZE PERCENT FINER SPEC.' PERCENT PASS? (X=NO) 2 100 100 1.5 100 90 - 100 1 91 3/4" 75 50 - 90 3/8" 55 #4 43 30 - 50 #8 35 #16 31 #30 27 #50 16 #100 10 #200 7.5 3.0 - 12 % Fines Fine silt C 14 8 Soil Description 1.5" Aggregate Base Course Atterbera Limits PL= NP LL= NV PI= NP Coefficients D90= 24.9474 D85= 22.8025 D60= 11.3272 D50= 7.1279 D30= 0.9964 D15= 0.2673 D10= 0.1500 Cu= 75.51 Cc= 0.58 Classification USCS= GP -GM AASHTO= A-1-a Remarks See Figure 1 for standard Proctor compaction results. CDOT Class 4 Aggregate Base Course (1.5") Location: Northeast Corner of Project - Flag Sand & Gravel Sample Number: 341-19 Date: 8/20/2019 Kumar & Associates, Inc. Client: CoreyDePaolo Project: Six Lazy K Road, South of Silt, Garfield County, Colorado Glenwood Springs, Colorado ;I Project No: 19-7-238 Fiaure 1A Tested By: KO Checked By: DAY