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Home My WebLink AboutObservation of Excavation 05.15.17H-PryKUMAR Geotechnical Engineering I Engineering Geology Materials Testing I Environmental 5020 County Road 154 Glenwood Springs, C0 81601 Phone: (970) 945-7988 Fax: (970) 945-8454 Email: hpkglenwood@kumarusa.com Office Locations: Parker, Glenwood Springs, and Silverthorne, Colorado i|l4.ay 15,2017 RM Construction Attn: Will Zeman 5030 County Road 154 Glenwood Springs, Colorado 81601 (will @ builtwithrm.com) Project No. 17-7-129.4 Subject:Observation of Excavation and Summary of Compaction Testing, Proposed Residence, Lot 31, Heron Crossing at Ironbridge, 1699 River Bend Way, Garfield County, Colorado Gentlemen: As requested, a representative of H-P/Kumar observed the excavation at the subject site and performed compaction testing on May 10 and 15,2017 to evaluate the soils exposed for foundation support. The findings of our observations and recommendations for the foundation design are presented in this report. H-P/Kumar previously conducted a subsoil study for design of foundations at the site and presented our findings in a report dated January 24,2011, Project No. 17-7-129. The proposed residence will be a single-story building over crawlspace in the living area with an attached garage with a slab-on grade floor supported on shallow spread footings. Our subsoil study recommended an allowable soil bearing presslrre of 1,000 psf with the footing bearing level at least 4 feet below existing ground surface and no more than 'l feet of compressible soils below the bearing level. The footing areas were reportedly sub-excavated 2 feet and structurally backfilled to re-establish the bearing level to meet this recommendation. At the time of our visit to the sité on May 10, the foundation excavation was cut in two livels from lVz to 3Vz feet below the adjacent ground surface. The soils exposed in the bottom of the excavation consisted of compacted slightly moist silty clay with sand. Two of three compaction tests performed indicated relative compaction below our recommended minimum of 987o for structural fill below footings apparently due to their dry compacted condition. On May 15, the footing areas had reportedly been re-worked and we performed two re-tests that indicated the recommended minimum compaction was obtained. Our field and laboratory compaction test reports are attached for reference. The clay soils exposed in the excavation in their native and compacted condition are consistent with those previously encountered on the site and suitable for support of spread footings designed for the recommended allowable bearing pressure of 1,000 psf with the risk of RM Construction l|l4ay 15,2017 Page 2 settlement mainly if the bearing soils are wetted. Loose disturbed soils should be moistened and compacted. Other recommendations presented in our previous report which are applicable, especially those to keep the bearing soils dry, 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. 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 ftrrther assistance, please call our office Sincerely, H-P+ KUMAR Westhoff, CET Reviewed By: Steven L. Pawlak, Attachments: Earthwork Reports (4 pages) TJV//ljf H-P\KUMAR Project No. 17-7-129.4 Test No. Location Footing Areas Depth or Elev. Field Dry Density (pcr) Field Moisture Content % Field Comp. (%) Min. Comp Req. (o/o\ Proctor Lab No. 1 Stepped-down footing in garage area, l0'W of NE corner of excavation footing grade 98.4 5.6 88 98 068-17 2 Center of west-side footing area footing qrade 109.1 10.6 98 98 068-17 SE corner of excavation 8.6 068-17 Lab No Method 3 98.5 88 98 Description Dry footing rade opt. Moist. Max. Dens. 068-17 ASTM D 698 Silty Clay with Sand 111.4 13.1 H-P*I<UMAR 5020 County Road 154 Glenwood Springs, CO 81601 Phone: (970) 945-7988 Fax: (970) 945-8454 Email; hnkglenwood@kumarusa.com i ,:' irl;: ¡ t : l r rii. ;li :r: r, jli 1: :i, i,:. i ; !--: rl, jt¡:¡:t :t i, :¡: (.ii.li[.:i ;:-] :!i .'.,: .i r,i, ¡,"',' Office Locations: Parker, Glenwood Springs, and Silverthorne, Colorado Earthwork Compact¡on Testing Report Client: RM Construction Project No.: 17-7-129.A Day: Wednesday Attn: WillZeman Date: 5110117 5030 County Road 154 Report No.: I Page: 1 of 1 Glenwood Springs, Golorado 81601 Project: 1699 River Bend Way, Lot 31, Heron Crossing at lronbridge, Garfield Gounty, Golorado Weather: Partly cloudy, calm, dry Temperature: 62" at 12:50 pm Earthwork Contractor: RM/Dirtworks Equipment Used: Description of Earthwork Tested: Sample(s) Obtained: Verbal Communication: Placement and Compaction Procedure: Not observed by H-P/Kumar Max. Rock Size Moisture Conditioning: Number of Passes Nuclear Gau e Moisture/Dens Test Results Proctor Sam Reference FILL COMPACTIVE EFFORT AND MOISTURE TO FILL DURING THE TIMES WHEN OUR OBSERVER IS NOf OBSERVING OPERATIONS, THE NUCLEAR DENSOMETER METHOD OF TESTING WAS USED IN SUBSTANTIAL ACCORDANCE WITH ASTM D 6938. Distribution: RM Construction - Will Zeman (will@buildwithrm.com) TJW Thomas J. Westhoff. CET Steven L. Pawlak, P.E Field Technician Reviewed By Not observed Footing areas had reportedly been sub-excavated 2 feet and replaced using excavated material. Two of the three tests performed were judged to be below our recommended 98% minimum compaction with moisture contents well below optimum. Reference Proctor value was not available at the time of testing. One large bulk sample of the excavated soil was obtained and submitted to our lab for standard Proctor and classification testing. Lab results are attached. Will with RM was informed of our test results. Per Will, footing areas will be re- worked and re-tested. Lift ïhickness. Compactor(s) Used COMPACTION TEST REPORT 114 112 oo-j .È Ú,c c)!¡ô 110 108 106 ZAV for SP.G. = 2.45 104 I 10.5 12 13.5 Water content, % 15 16.5 18 Test specification: ASTM D 698-07 Method B Standard Rl19 ---u 4 i-;;A \ Elev/ Depth Classification Nat. Moist.sp.G.LL PI Yo> 3/8 in o/o < No.200USCSAASHTO CL.ML A-4(3)25 5 0.0 ft1 TEST RESULTS MATERIAL DESCRIPTION Maxirnurn dry density: I I 1.4 pcf Optirnrrm moisture :13.1 % Silty Clay with Sand Project No. 11-7-129.A Glient: RM Construction Project: I 699 River Bend Way, Lot 3 I , Ileron Crossing at lronbridge, Garfield County, Colorado o Location: Site Stoc ile s e Number: 0ó8-17 Kumar & Associates, lnc I Coloradonn Remarks: See Figure 1A for classification results. Figure 1 Tested By:KO Checked By : SLP I I I Particle Size Distribution Report c¿ i i.; i.g .ç ; ; ÑÈ :S S c ooooooooso(!r)t@-rC!**ûtËtss a t l.rlz tr Fzulo É. I.IJ o_ 100 90 80 70 60 50 40 30 20 10 0 '10 20 30 40 50 60 70 BO 90 100 !mnc)mz--loo n CNmn 0 100 GRAIN SIZE - mm. % +3'% Gravel % Sand Goarse Medium Fine % Fines sitr ClayCoarseFine 0 0 I 0 I l6 82 (no specifi cation provided) Location: Site Stockpile Sample Number: 068-17 Date: 5/1012017 SIEVE stzE PERCENT FINER SPEC.- PERCENT PASS? (X=NO) .37 5 #4 #8 #16 #30 #54 # 100 fÍ200 100 99 99 99 98 91 93 82 Mate ria I Descrip__tjqn Silty Clay with Sand PL= 20 P90= o'1187 H50_u10- USCS= CL-MI- Atterberg Limitg. LL= 25 Coefficients Dqc= 0.0871 LJl^- uu= Classification AASHTO= Pl= 5 itg=uc= A-4(3) Remarks See Figure 1 for standard Proctor compaction results. Kumar & Associates, lnc. Glenwood Sprinqs, Golorado Glient: RMConstruction Project: 1699 River Bend Way, Lot 3l , Heron Crossing at Ironbridge, Garficld County, Colorado Proiect No: 1l-7-129.A Fiqure lA Tested By KO Checked By:SLP Test No. Location Footing Areas Depth or Elev. Field Dry Density (pcÐ Field Moisture Content Vo Field Comp ("/ù Min. Comp Req. e/") Proctor Lab No. 1A Re-test of Test #1 (51101171 Stepped-down footing in garage area, 10'W of NE corner of excavation footing grade 110.2 6.5 99 98 068-17 footing 109.5 9.7 068-17 Lab No Method Description 3A 98 98 Max. Dry Dens Re-test of Test #3 (51101171 SE corner of excavation opt Moist. 068-17 ASTM D 698 Silty Clay with Sand 111.4 13.1 H-P*l<UMAR 5020 County Road 154 Glenwood Springs, CO 81601 Phone: (970) 945-7988 Fax: (970) 945-8454 Email: hpkglenwogd@ktlme¡UgLm i ,:'::Ì¡ 'tirir;ii ir':,liirr¡:t:lilI,; I i:;ri;ìllir:;ti¡:t íì1.;,¡Ìr;tll; l:..1.i .'i,l:r, It,',i:tt.. i i rì.]ìr'1rrì:iÌíilli.tl Office Locations: Parker, Glenwood Springs, and Silverthorne, Colorado Earthwork Compact¡on Testing Report Client: RM Gonstruction Project No.: 17-7-12g.A Day: Monday Attn: Will Zeman Date: 5115117 5030 County Road 154 Report No.: 2 Page: I of 1 Glenwood Springs, Colorado 81601 Project: 1699 River Bend Way, Lot 31, Heron Crossing at lronbridge, Garfield County, Colorado Weather: Partly cloudy, light wind, dry Temperature:62o at l0:00 am Earthwork Contractor: RM/Dirtworks Equipment Used: Description of Earthwork Tested. Verbal Communication: Not observed Footing areas had reportedly been re-worked. Two re-tests were performed. Re-tests met our recommended 98% minimum compaction. Moisture content readings were 6.6 and 3.4o/o below optimum as the test areas had dried over the weekend after completion of re-work. Willwith RM was informed of our test results. Placement and Compaction Procedure: Not observed by H-P/Kumar Lift Thickness:Max. Rock Size:Moisture Conditioning Compactor(s) Used Number of Passes Nuclear Gau Moisture/Den Test Results Proctor Sa Reference PRESENTS COMPACTIVE EFFORT AND MOISTURE TO FILL DURING THE TIMES WHEN OUR OBSÊRVER ts OBSERVI NG OPERAIIONS THE NUCLEAR DENSOMETER METHOD OF TESTING WAS USED IN SUBSTANTIAL ACCORDANCE WITH ASTM D 6938. Distribution: RM Construction - will Zeman (w¡ll@bu¡ldw¡thrm.com) Thomas J. Westhoff, CET Steven L. Pawlak, P.E. TJW/ Field Technician Reviewed By