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Observation of Excavation
An Employee- Owned C# mpony www1umarusaxom Office Locations: Denver (HQ), Parker, Colorado Springs, Fort Collins, Glenwood Springs, and Summit County, Colorado June 26, 2023 Simon Casas 31 Royal Coachman Garfield County, Colorado 81601 simoncasaslopez(&,hotmail. com Project No. 21-7-202.A Subject: Observation of Excavation, Proposed Residence, Lot 28, Roaring Fork Mesa, Aspen Glen, 31 Royal Coachman, Garfield County, Colorado. Dear Simon: As requested, a representative of Kumar & Associates, Inc. observed the excavation at the subject site on June 23 and 26, 2023 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 April 20, 2021, Project No. 21-7-202. The proposed residence will be a wood -frame structure over a partial lower basement level with attached garage. The footings have been sized for an allowable bearing pressure of 2,000 psf. At the time of our visit to the site, the foundation excavation had been cut in two levels from 2 to 10 feet below the adjacent ground surface. The soils exposed in the bottom of the excavation consisted of medium dense, silty sand with scattered gravel. The results of a gradation analysis performed on a sample of silty sand (minus 1'/2-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 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. 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. Simon Casas June 26, 2023 Page 2 If you have any pestions or need. further assistance, please call our office. Sincerely, Ktuimar ,Akuss;soclilawok s, 58663 James H. Parsons Reviewed by-, W� 11 UP, Daniel E. Hardin, P.E. a r 1 ttaelmient, figure I — Gradation Test Results Nko,,, 21-7-202A 100 90 80 70 60 50 a_ 40 30 20 10 0 . C HYDROMETER ANALYSIS SIEVE ANALYSIS TIME READINGS U.S. STANDARD SERIES CLEAR SQUARE OPENINGS 24 HRS 7 HRS 45 M.I.N ......1 .1....5..11 M.I.N .60M ..IN....1.9M.IN ....4M.I.N.................I....MIN ................ --... 2..0........0...... _............. ............ ............................................ 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I .......... z ----------- . ............ ....... ... ... .... .... .. ......... .............................. ............. ... ........... . . ..... .. .... .... . . I ....... I ............. ............. ........ ...... I.). ...... a- .... .......... ............. ..... .... . 19 ....... .............. . ....... .......... J . ... ... ... ...... I ......... ...... 100 101 .002 .005 .009 .019 .075 1 0C) .18 .600 1 i.'S6 4.79" "9*. 76.2 127 1 200 38.1 .425 2.0 152 DIAMETER OF PARTICLES IN MILLIMETERS SAND GRAVEL CLAY TO SILT COBBLES FINE I MEDIUM ICOARSE FINE I COARSE PN 21 —7-202A 6 w GRAVEL 44 Y. SAND 40 Y. SILT AND CLAY 16 Y. LIQUID LIMIT PLASTICITY INDEX SAMPLE OF: Silty Sand and Gravel FROM: SD-1 @ 10' These test results apply only to the samples which were tested. The testing report shall not be reproduced, except In full, without the written approval of Kumar & Associates, Inc. Sieve analysis testing is per -formed in accordance with ASTM D6913, ASTM D7928, ASTM C136 and/or ASTM D1140. Kumar & Associates GRADATION TEST RESULTS I Fig. 1