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Home My WebLink AboutSubsoils StudyI (;lA H3ffi fi*Tf$ffi i'i:'i *"' An Employoa Owncd Compony 5020 County Road 154 Glenwood Springs, CO 81601 phone: (970) 945-7988 fa"x: (970) 945-8454 emai I : kaglenwood(@kumarusa. com www.kumarusa.com Office Locations: Denver (HQ), Parker, Colorado Springs, Fort Collins, Glenwood Springs, and Summit County, Colorado April29,2024 City of Glenwood Springs Police Department Attn: Mike Young 101West 8th Street Glenwood Springs, Colorado 81601 mike.youne@cogs.us Job No. 24-7-258 Subject: Subsoil Study, Proposed Shoot House for City of Glenwood Springs at South Canyon Range, Highway 134, Garfield County, Colorado Dear Mr. Young: As requested, Kumar and Associates, Inc. performed a subsoil study for design of foundations at the subject site on April 23,2024. The study was conducted in accordance with our agreement for geotechnical engineering services to you dated April 23,2024. The data obtained and our recommendations based on the proposed construction and subsurface conditions encountered are presented in this report. Proposed Construction: The proposed structure will be a one-story structure constructed of railroad ties with an overhead observation catwalk. All walls will consist of two parallel stacked railroad tie walls with granular material placed in the air gap between the stacks of ties. No finished floors are currently planned. Cut depths are expected to be about 1 to lYzfeet. Foundation loadings for this type of construction are assumed to be relatively light. If building conditions or foundation loadings are significantly different from those described above, we should be notified to re-evaluate the recommendations presented in this report. Site Conditions: The building site is located on the east side of the South Canyon Shootiilg Range on the site of the previous shoot house. The ground surface is level, and covered with about 9 inches of asphalt and gravel fill with scattered grass and weeds. Subsurface Conditions: The subsurface conditions at the site were evaluated by excavating an exploratory pit at the approximate location shown on Figure 1. The log of the pit is presented on Figure 2. The subsoils encountered, below about 6 inches of asphalt and 3 inches of gravel fill, consist of medium stiff sandy clay down to the maximum explored depth of 4 feet. Results of swell-consolidation testing performed on relatively undisturbed drive samples of the clay soils obtained from the pit, presented on Figure 3, indicate low compressibility under light loading and low expansion when wetted. No free water was observed in the pit at the time of excavation and the soils were moist. Foundation Recommendations: Considering the subsoil conditions encountered in the exploratory pit and the nature of the proposed construction, we recommend the walls be placed on the undisturbed natural soil or compacted base course be designed for an allowable soil .' -L' bearing pressure of 1,500 psffor support ofthe proposed structure. The compacted gravel should consist of a well graded granular material such as road base and should extend outside the walls 6 inches for every foot of fill depth beneath the walls. Any existing topsoil, fill, and any loose and disturbed soils encountered at the foundation bearing level within the excavation should be removed and the footing bearing level extended down to the undisturbed natural soils. Foundations designed as described above can be expected to experience post construction movement of up to an inch or more from expansion of the bearing soils when they become wetted and from frost heave. Underdrain System: Although free water was not encountered during our exploration, it has been our experience in the area, and where clay soils are present, that local perched groundwater can develop during times of heavy precipitation or seasonal runoff. Frozen ground during spring runoffcan create a perched condition. The proposed construction does not require an underdrain system. Surface Drainage: The following drainage precautions should be observed during construction and maintained at all times after the structure has been completed: 1) Excessive wetting or drying of the foundation excavations should be avoided during construction. Drying could increase the expansion potential of the soils. 2) The ground surface surounding the exterior of the building should be sloped to drain away from the foundation in all directions. We recommend a minimum slope of 6 inches in the first 10 feet. Limitations: This study has been conducted in accordance with generally accepted geotechnical engineering principles and practices in this area at this time. We make no waranty either express or implied. The conclusions and recommendations submitted in this report are based upon the data obtained from the exploratory pit excavated at the location indicated on Figure 1 and to the depth shown on Figure 2,the proposed type of construction, and our experience in the area. 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. Our findings include interpolation and extrapolation of the subsurface conditions identified at the exploratory pits and variations in the subsurface conditions may not become evident until excavation is performed. If conditions encountered during construction appear different from those described in this report, we should be notified at once so re-evaluation of the recommendations may be made. This report has been prepared for the exclusive use by our client for design pu{poses. We are not responsible for technical interpretations by others of our information. As the project evolves, we should provide continued consultation and field services during construction to review and monitor the implementation of our recommendations, and to verify that the recommendations have been appropriately interpreted. Significant design changes may require additional analysis or modifications to the recommendations presented herein. We recommend on-site observation Kumar & Associates, lnc. @ Project No. 22-7-258 -J- of excavations and foundation bearing strata and testing of structural fill by a representative of the geotechnical engineer. If you have any questions or'if we may be of further assistance, please let us know. Respectfully Submitted, Kumar & Associates, Inc. David A. Noteboom, Staff Reviewed by: James H. Parsons, P attachments Figure 1 Pits Figure 2 -Pits Figure 3 - Swell-Consolidation Test Results Kumar & Associates, lnc. @ Proiect No. 22-7-258 t 5lr t '{t.* .41 ;:L I t a +'{ .tu .a a) Plr 1 t-. ./ a I"I *8,'\ {: t 10 0 0 APPPROXIMATE SCALE_FEET 24-7 -258 Kumar & Associates LOCATION OF TXPLORATORTY PIT Fig. 1 WC=17.8 DD= 1 09 PIT 1 0 (6) (5) 0 FlrJtrll! I :fF(L LJo tNC=17.3 DD= 1 06 FLI lrJ LL I-F(L trlo 5 5 LEGEND (.) = ASeHALT, THtcKNEss tN TNcHES sHowN rN eARENTHEsEs ro LEFT oF THE LoG. (t) m BASE couRsE, THT.KNESS rN TN.HES sHowN rN 'ARENTHESES To LEFT oF THE LoG l;ri r:;ir::l cLAy (cL) SANDY, S|LTY, MEDIUM STIFF, MOIST, MEDIUM BROWN F HAND DRIVE SAMPLE. NOTES 1. THE EXPLORATORY PIT WAS EXCAVATED BY THE CLIENT PRIOR TO OBSERVATION WITH A BACKHOE. 2. THE LOCATION OF THE EXPLORATORY PIT WAS MEASURED APPROXIMATELY BY PACING FROM FEATURES SHOWN ON THE SITE PLAN PROVIDED. 3. THE ELEVATION OF THE EXPLORATORY PIT WAS NOT MEASURED AND THE LOG OF THE EXPLORATORY PIT IS PLOTTED TO DEPTH. 4. THE EXPLORATORY PIT LOCATION SHOULD BE CONSIDERED ACCURATE ONLY TO THE DEGREE IMPLIED BY THE METHOD USED. 5. THE LINES BETWEEN MATERIALS SHOWN ON THE EXPLORATORY PIT LOG REPRESENT THE APPROXIMATE BOUNDARIES BETWEEN MATERIAL TYPES AND THE TRANSITIONS MAY BE GRADUAL. 5. GROUNDWATER WAS NOT ENCOUNTERED IN THE PIT AT THE TIME OF EXCAVATION 7. LABORATORY TEST RESULTS: WC = WATER CONTENT (%) (ASTM D 2216): DD = DRY DENSITY (PCt) (ISTV D 2216). LOGS OF EXPLORATORY PITS Fig. 224-7 -258 Kumar & Associates € SAMPLE OF: Sondy Cloy FROM:PitlO3.5' WC = 17.5 %, DD = 106 pcf EXPANSION UNDER CONSTANT PRESSURE UPON WETTING N 1 JJlrjAo I z.o -l o =oA-cz.oo -5 -4 1 0 1 2 -3 PRESSURE - KSF 10 APPLIED PRESSURE - KSF IO 100I JJut =tn I z.otr o =o UIz.o() SAMPLE OF: Sondy Cloy FROM:Pii 1 @ 3.5' WC = 17.8 %, DD = 109 pcf Ihil i-t Eult! oppt ont b h $mpL. H.d. Ih. bdlry mtt lholl not ba wduc.d, crcft ln full, rlthdt thr ,rlttff oDml of Xumr ond Aslcl6. |rc. Sr.l Comllddfon t6ltE tsrlbdFd ln Godo@ dltr lSlU 0-,L,+6. EXPANSION UNDER CONSTANT PRESSURE UPON WETTING 100 24-7-258 Kumar & Associates SWELL_CONSOLIDATION TEST RESULTS Fig. 3