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Home My WebLink AboutObservation of Excavation 09.27.2021I n.,,t ij'ffi';'åätrn'"'Ë; ;' ** An Employcc Owncd Compony 5020 County Road 154 Glenwood Springs, CO 81601 phone: (970) 945-7988 fax: (970) 945-8454 email: kaglenwood@kumarusa.com www.kumarusa.com Office Locations: Denver (HQ), Parker, Colorado Springs, Fort Collins, Glenwood Springs, and Summit County, Colorado September 27,2021 Eric Conklin 1800 Black Diamond Road Glenwood Springs, Colorado 81601 conklinwelding@gmail'com project No. 2 r-7-75r Subject: Observation of Excavation and Exploratory Pit, Proposed ADU, I 800 Black Diamond Mine Road, Garfield County, Colorado Eric: As requested by Rick Perrin, a representative of Kumar & Associates observed the excavation at the subject site on September 15,2A2l to evaluate the soils exposed for foundation support. The findings of our observations and recommendations for the foundation support are presented in this report. The services were performed in accordance with our agreement for profbssional engineering services to you dated September 14,2021. The ADU will be located near the driveway entrance to the property on the uphill side. The development consists of cutting into the hillside up to around 8 feet deep to create a relatively level building site. Considering the cut depth, a retaining wall will be needçd for the cut slope support and provide an open area between the hillside and the building for drainage. The driveway and septic disposal area are between the ADU and the driveway. The hillside is covered with aspen and relatively heavy brush. At the time of our visit to the site, the building area had been cut in one level up to about I feet below the adjacent ground surface. A pit about I feet deep had been dug near the middle of the proposed building for subsurface soil information. The soils exposed in the bottom of the building and pit excavations consisted of stift sandy clay with scattered gravel and larger rocks. A considerable depth of topsoil had been removed. Results of swell-consolidation testing performed on a sample taken from the site, shown on Figure 1, indicate the soils are slightly to moderately compressible under conditions of loading and wetting. The results of an unconfined compression test on another sample indicates the clay soils are stiff. The laboratory test results are summarized in Table l. No free water was encountered in the excavation and the soils were moist. 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 can be used for support of the proposed ADU building and retaining wall. The exposed soils tend to compress under conditions of loading and wetting and post-construction settlement of the foundation should be relatively minor around I inch or less. Footings should be a minimum width of 16 inches for continuous walls and 2 feet for columns, Eric Conklin September 27,2021 Page2 Loose disturbecl soils and any remaining topsoil in footing areas should be removed and the bearing level extended down to the undisturbed natural clay 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 founclation drain should be provided to prevent temporary buildup of hydrostatic pressure behind the uphill retaining wall and crawlspace walls and prevent wetting of the lower level. Structural fill placed within floor slab areas should consist of imported granular soils such as road base compacted to at least 95% of standard Proctor density at a moisture content near optirnum. Backfill placed around the structure should be compacted and the surface graded to prevent ponding within at least 10 feet of the building. Landscape that requires regular heavy irrigation, such as sod, and sprinkler heads should not be located within 5 feet of the foundation. The recommendations submitted in this letter are based on our observation of the soils exposed within the foundation and pit excavations and assume the soils across the building area and beneath the footings have equal or better support than those exposed. Variation in the subsurface conditions could increase the risk of foundation movement and change the recommendations contained in this letter. Our services do not include determining the presencs, 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 offtce. Sincerely, å{r¿¡nr¡1" o!ü ;{sst¡cia{esu Tnc, Steven L SLP/kac Attachrnents:Test Results Table 1-of Laboratory Test Results cc:Rick Perrin (sçk(}Ã!kpçIIn..cq$) Kumar & Associates, lnc. ''Project No.21-7-751 E ; I ;" e I 1 òs JJ¡J3vt I o t- o Jo u1zo(J 0 -1 -2 -3 -4 r.0 t0 SAMPLË OF: Sondy Cloy wlth Grovel FROM; Middle Areq WC = 1 7.7 %, DD = 102 pcf ADDITIONAL COMPRESSION UNDER CONSTANT PRESSURE DUE TO WETTING ôot rith bG 21-7 -751 Kumar & Associates SWTLL-CONSOLIDATION TTST RISULTS 1Fig l(tn :' Geotechnical and Materials Engineers and Env¡ronmêntal Scientists TABLE 1 SUMMARY OF LABORATORY TEST RESULTS I tf,ilTSrþNATSAfiIPLÊ LOCAÎION tpsFt ut{coNfl¡rED COMPRESSNE STRENGTH soll oR BEDROCK TYPE NAÏURÂI DRY DEI{SITY fôêR GRAVEL (',6) SANO l,hl PERCENT PASSfi{G ¡t0. 200 stEvE t%l LIOUID LIMÍI l%ì PLASTIC INOEXBOTTOM OF EXCAVATION NATURAL üofsruRE coilÎENl lvot Sandy Clay with GravelMiddle Area t'7.7 t02 Sandy Clay2050Southwest Corner 24.5 95 No,2l'7'75'l 5TÄfE OF COLOTüDO OTFICE OF TI"IE STATE ËNGINEIB Division of Water Resources Department of Natural Resources 1313 Sherman Street, Room 818 Denve¡, C<¡lorado 80?O3 Phone (301) 866-3581 fAX (lo3) 866-3589 December 22,1993 Roy Romer Covernor Ken Salazar Execul¡ve Director Hal D. Simpson State Engineer POLICY MEMORANDUM 93-4 SUBJËCT: Use Hestrictions for Permits lssued as the Only Well on 35+ Acres The tollowing standards are adopted as policy to provide for the consistênt êvâluation and cond¡tionlng of applications for nêw well pêrmits and requests to amend the use of existing wêlls approved as the only exempt wellon a tract of 35 acres or mere under the provisions of Seçtion 37-92-602(SXbXll). Only wells outside designated ground water basins are affêctêd. This policy becomes effectivs January 1, 1994 and shall be modified or revoked only in wr¡ting. 1. New well psrmits approvêd pursuant to Section 37-92-602(3XbXlD0 as the only wellon a tract of 35 åcrês or more and for use as deecribed in 37-92-602(1Xb), shall be conditioned to provlde for aflthe uses described in that subsêction, including use in up to threo (3) síngle-family dwellings, regardless of whether or not the applicant requêsted any specific numþer of dwell¡ng unlts or all the other uses. Provided that lf the only use requêstêd is watering of llvestock on a farm or ranch such permit will limited the use to only watering of livestock on a farm or ranch. 2.Requests to amend existing well permits, issued under the provlsion of Section 37-92- 602(SXbXll)(A) [ or 602(SXbXll) ] as the only well on a tract of 35 acres or more, to allow use for all or any of the uses described in Subsection 37-92€02(1)(b), including use in up to three single-family dwellings, shal¡ be approved provided the documents indicated below are submitted. No fee shall be charged for this serv¡ce. A request to amend is appropriate any time the condition of approval uses are less than or not specific to the use desired. A letter, s¡gned by the applicant, requesting the permit amendment and addressing the uses desired. lf the applicant for the amendment is not the original applicant of record in the Division's files, an application for a change in ownêrship/address (Form No. GWS- 11) and a copy of a deed showing that they are the owner(s) of the 35+ acrês described in the existing well permit, c.A legal description of the 35+ acre tract, if that lnformatlon has not already been provided. a. b, w, HD$/SPUsl Statê Engineer Policy 93-4December 22, 1993Page 2CONSIDERATIONS AND BACKGHOUND FOR POLICY MEMO 93.4PROBLEMA procedure adopted in 1981 or 1982 requlred all permits, approved under the provlsions of Sections37-92-6O2(SXbXll) as the only well on a tract of 35 acres or more, to be limited to serving one single-family dwelling unless specifically indicated otherwise in the application. This has resulted in additionalwork and expense for the Division, and additional expense for the well owners when applioations forextended use of the exlsting wells were required.Drscus$toNThe existing procedure was a response to a belief that if we did not limit use on thesE 35+ acre tractsto only one dwelling, a proliferation of dfuisions ol land would occur from counties exempting certaindivisions of land. This would result in an increased potêntial for injury to other water rights inoverappropriated systems.It has been the Division's experience that our restrictions dld not result in a reduction of the number ofdivisions of land that were occurrlng, and that our procedure only forced well owners to apply for permitsto extend the use of their existing wells, which would then be approved since the Division did not findthat there was sufficient evldence of injury to overcome the presumptions as provided ln Section 37-92-602(SXbX|l)(A). This ultimately only resulted ln increased work for the Dlvision in approving well permitswhoee cost is not tully funded by the well permit applicatlon fees.SOLUTIONThree options appoar to þe available.Continue the current procedure of limiting to one dwelling, unless otherwise requested,and require filing of an application to expand the use of the well.Ëstablish a new policy that will ailow approvalfor up to three single family dwellings, forall new permits approved for domEstic type use on 35+ acre tracts, and will allow foramending existing permits.Revoke the current procedure concerning new well permits, but do not adopt a newpolicy.RËCOMMENÐATIONThe Second option åppëårs to be the most rsasonable since it provides clear direction to the staff andpublic, and reduces costs.2.3.r{û