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Home My WebLink AboutObservation of Excavation 08.19.22l(trt frmes & Assoslf,fisi, lng." Geotechnical and Materials Engineers and Fnvironmental Scientists An Employes Owned Compony 5020 County Road 1,54 {ilenwood Springs, CO 8160i phone: (970) 945-7988 fax: (970) 943-Btl54 emai I I kagleliwoo116)kunrarusa.com Itu \y,k-q |]i g$sa.-cp_nl Ollice Locations: Denver (HQ). parker; Coiorado Springs, l.-orl llollius, (jlenrvood Spriugs, and Sunrrlit {_-ounty, Colorarlo August 19,2022 Paul R. Cody 71 Windward Passage North Chatham, MA 02650 PrsodYi(Aaol.com Subject Project No. l8-7-625 observation of Excavation, Proposed Residence, Lot 32, Mountain springs Ranch, North l\{arsh Lane, Garfield County, Colorado Dear Paul: As requested by Ed Walters, a representative of Kumar & Associates, Inc. observed the excavation at the subject site on July 29,2t)22 to evaluate the soils exposed for folndation support' The findings of our observations and recommendations for the foundation design are presented in this report. These services are provided as supplernental to our professional Services Agreement to you dated July 10, 2019. We previously conducted a subsoil study fbr design of foundations at the site and presented our findings in a report dated Augu st 2g , 2019, Project No. l8-7-625. The proposed residence will be a single-story structure with slab-on-grade grouncl floor. The proposed residence will be supported on a spread fcroting foundation ilesigrred for the recornmended allowable bearing pressure of 2,500 psf. At the time of our visit to the site, the foundation excavation had been cut i1 multiple levels up to 10 feet below the adjacent ground surface. The soils exposecl in the bottom of the excavation consisted primarily of silty ciayey sand and gravel witli scattered cobbles. In shallow cut areas the exposed soils consisted tlf stiff, sancly clay. Results of swell-consolidation testing performed on samples taketl from the site, shown on Figure 1, indicate the clay soils possess a low compressibility potential under existing moisture conditions and light loadilg anci a low expansion potential when u'etted under constant light surcharge. No free water was encountered in the excavation and the soils were slightly moist to rnoist. The clay soil possesses ar1 exp*nsiori poterrtial when wetted ancl could cause slab heave and foundation distress. We recomntend the clay soils be removecl from below spread footing a'd slabs-on-grade areas and the foundation bearing level be re-established with the onsite or irnported gianular soil moisture conditioned ancl placed as compacted structural fill. The gravel soils 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 2.500 psf. Ciay soils and loose disturbed soils should be removed in the footing areas to expose the undisturbed natural soils. Other recommendations presented in our previous report whicli are applicable should also be observed. i I I Paul R. Cody August 19,2022 Page2 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 ofpractice should be consulted. If you have any questions or need further assistance, please call our office. Sincerely, Kumar & Associates, Inc. y,,"rr4-T. ?qx'ua,? James H. Parsons, P.E. Reviewed by: Steven L. Pawlak, JHPlkac attachments Cc: Figure 1 Test Results Table I - Summary of Laboratory Test Results John Cody (drAfoxl@aolsam) Ed Walters (info@rvaiterscorupanv.net) 15222{, Kumar & Associates, lnc. {'Project No. 18.7.625 FROM: Bottom of Excovolion, Norlh End WC = 35.6 %, DD = g2 pcf SAMPLE OF: Sondy Cloy S{cll in EXPANSION PRESSURE UNDER UPON CONSTANT WETTING JJ UJ =UI I z.9F o =o(n z.o C) 0 -1 -2 -3 1.0 t0 18-7 -625 Kumar & Associates SWELL_CONSOLIDAIION IEST RESULIS Fig. 1 I t I E I (+rt fliffil#fffifnii:.i *", TABLE 1 SUMMARY OF LABORATORY TEST RESULTS No.18.7.625 sotL oR BEDROCK TYPE Sandy Clay with Gravel Sandy Clay UNCONFINED COMPRESSIVE STRENGTH PERCENT PASSING NO. 200 sIEVE LIQUID LIMIT PLASTIC INDEX 67 SAND $l('/"1 GMVEL GRADATIONNATURAL MOISTURE CONTENT NATURAL DRY DENSITY 82 22.0 3s.6 SAMPLE LOCATION North End BOTTOM OF EXCAVATION South End