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Home My WebLink AboutSubsoils ReportI (3A Hiffi,*ffiff*:fr'"'n ;' *^ An Employcc Owncd Compony 5020 County Road 154 Glenwood Springs, CO 81601 phone: (970) 945-7988 f-ax: (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 March 6,2024 Cole Ule 7999 County Road 312 New Castle, Colorado 81647 sledneckO26@vahoo.com Subject Project No.24-7-175 Preliminary Subsoil Observation of Backhoe Pits for General Site Grading Recommendations, Proposed Building Pads, Tracts 17 and 18, Grand Hogback Ranches, South of County Road 335, Garfield County, Colorado Dear Cole As requested, Kumar & Associates performed preliminary subsoil observation for general grading and fill recommendations at the subject site. The data obtained and our recommendations based on the proposed construction and subsurface conditions encountered are presented in this report. The study was conducted in accordance with our agreement for geotechnical engineering services to Cole Ule dated February 28,2024. Proposed Construction: The proposed building pads will be cut, and fill graded with onsite materials generally as shown on Figure 1. The cut and fill depths are expected to range between about 0 to 16 feet. The deepest cuts are generally the result of stockpiled topsoil artificially raising the ground surface elevation. The stockpiles will be removed as part of the grading. If grading plans are significantly different from those described above, we should be notified to re-evaluate the recommendations presented in this report. Site Conditions: The subject site was vacant at the time of our field exploration. The ground surface was variable, generally sloping down to the north at grades of up to 50o/o. Tract I 8 was previously graded in2022 with cuts and fills to a slope of about l0 percent down to the north. The cleared brush, oversized rocks and stripped topsoil were stockpiled on Tract 17. The cut slopes on Tract 18 exposed clayey sand and gravel soils. Vegetation consists of weeds, grass and sage brush. Subsurface Conditions: The subsurface conditions at the site were evaluated by observing 6 exploratory pits excavated by the client at the approximate locations shown on Figure 1 by the client. The logs of the pits are presented on Figure 2. The subsoils encountered in the pits on Tract 17 consist of l% to 3 feet of topsoil or clayey sand fill over medium dense clayey sandy gravel down to the maximum excavated depth of l1% feet. The subsoils encountered in the pits .| -L- on Tract l8 consist of lzfoot of topsoil overlying relatively dense, clayey gravel and cobbles on the south side of the lot and up to 11 feet of clayey gravel and cobble fill on the north side of the lot. The fill was reportedly compacted in lifts; however, compaction testing was not performed. Pit 5 on the northwest corner of Tract 18 encountered natural clayey sand and gravel below the fill from 6Vzto SVzfeet deep. No free water was observed in the pits at the time of excavation and the soils were slightly moist to moist. Laboratory testing including gradation, Atterberg limits testing and standard Proctor compaction is being completed at the time of our study. The completed laboratory testing will be presented under a separate cover. Site Grading: The risk of construction-induced slope instability at the site appears low provided cut and fi1l depths are limited. We assume the cut depths will not exceed one level, about 10 to 12 feet. Embankment fills should be limited to about 10 to l5 feet deep and be compacted to at least95Yo of the maximum standard Proctor density near optimum moisture content. Prior to fill placement, the subgrade should be carefully prepared by removing all vegetation and topsoil. The subgrade should be scarified to a depth of 8 inches, moisture conditioned to near optimum and compacted to at least 95Yo of the maximum standard Proctor density. The fill should be benched horizontally into the portions of the hillside exceeding 20o/o grade. Some settlement of deeper fills should be expected, even if the material is placed correctly, and could result in distress to facilities constructed on the fill. A lower risk option would be to compact the fills to at least 98 % of the maximum standard Proctor density. Permanent unretained cut and fill slopes should be graded at2horizontalto I vertical or flatter and protected against erosion by revegetation or other means. The risk of slope instability will be increased if seepage is encountered in cuts and flatter slopes may be necessary. If seepage is encountered in permanent cuts, an investigation should be conducted to determine if the seepage will adversely affect the cut stability. A representative of the geotechnical engineer should observe the placement and compaction of fill grading on a regular basis. 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 pits excavated at the locations indicated on Figure 1 and to the depths shown on Figure 2, the proposed type of construction, and our experience in the area. 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 mav be made. Kumar & Associates, lnc. o Project No. 24-7-'175 -J- This report has been prepared for the exclusive use by our client for preliminary design purposes. We are not responsible for technical interpretations by others of our information. Significant design changes may require additional analysis or modifications to the recommendations presented herein. We recommend on-site observation of the grading and compaction testing of structural fills 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, lnc. James H. Parsons, P.E. Reviewed by: David A. Y P attachments Figure I - Location of Exploratory Pits Figure 2 - Logs of Exploratory Pits /z/z{ tl. Kumar & Associat€s, lnc. @ Project No. 24-7-175 PROPERIY LINE PROPERIY LINE d L .*,$?,f"*. ^rq .-4 7 50 APPROXIMATE SCALE-FEIT COLORADO RIVER ROAD ENNANCE +r- ---PlT 6't '...: ROCK PILE -BRUSH PILE ROCK PILE 1 PIT 1 ROCK PILE PIT STOCKPILE TOPSOIL 24-7 -175 Kumar & Associates LOCATION OF EXPLORATORY PITS Fig. 1 .t 3 * & +. o s o s s s o PIT 1 E1.5612' PIT 2 EL. 5603' PIT 5 EL. s612' 0 0 5 5 FLJ lrJtL I-F(L lrJo I I I F LJ trJ LL IIF(L UJo 10 10 15 15 PIT 4 EL. 5620.5' PIT 5 EL. 5605.5' PIT 6 EL. 5604' 0 0 q 5 Ftd lrJtL I-F TLLIo F LrJ LJl! I-F(L LJo 10 10 s o s o S o S 15 15 24-7-175 Kumar & Associates LOGS OF EXPLORATORY PITS Fig. 2 a. * & LEGEND TOPSOIL: SAND AND CLAY, GRAVELLY, ORGANICS, FIRM/FROZEN, BROWN. FILL 1; SAND, CLAYEY TO VERY CLAYEY, COAL FRAGMENTS, GRAVELLY, SCATTERED COBBLES, MEDIUM DENSE, MOIST, BROWN TO DARK BROWN. FILL 2; GRAVEL AND COBBLES, CLAYEY TO VERY CLAYEY, SCATTERED BOULDERS, SANDY, DENSE, MOIST, BROWN, PREVIOUSLY PLACED AS COMPACTED FILL. GRAVEL AND COBBLES (GC); CLAYEY TO VERY CLAYEY, SANDY, SCATTERED BOULDERS, MEDIUM DENSE TO DENSE, MOIST, BROWN. t DISTURBED BULK SAMPLE. t PRACTICAL DIGGING REFUSAL. NOTES 1. THE EXPLORATORY PITS WERE EXCAVATED WITH AN EXCAVATOR ON FEBRUARY 29, 2024. 2. THE LOCATIONS OF THE EXPLORATORY PITS WERE MEASURED APPROXIMATELY BY PACING FROM FEATURES SHOWN ON THE SITE PLAN PROVIDED. 5. THE ELEVATIONS OF THE EXPLORATORY PITS WERE OBTAINED BY INTERPOLATION BETWEEN CONTOURS ON THE SITE PLAN PROVIDED. 4, THE EXPLORATORY PIT LOCATIONS AND ELEVATIONS SHOULD BE CONSIDERED ACCURATE ONLY TO THE DEGREE IMPLIED BY THE METHOD USED. 5. THE LINES BETWEEN MATERIALS SHOWN ON THE EXPLORATORY PIT LOGS REPRESENT THE APPROXIMATE BOUNDARIES BETWEEN MATERIAL TYPES AND THE TRANSITIONS MAY BE GRADUAL. 6. GROUNDWATER WAS NOT ENCOUNTERED IN THE PITS AT THE TIME OF EXCAVATION. o S' o 24-7-175 Kumar & Associates LEGEND AND NOTES Fi9. 5 /d,. u J,. 'tJ .. i