Loading...
HomeMy WebLinkAboutSoils Report 04.16.2017Huddleston -Berry Engineering & Testing, LLC RC Construction 18 Valley View Place Parachute, Colorado 81635 Attention: Mr. Russell Cartwright Subject: Geotechnical Investigation 38 Snowberry Place Parachute, Colorado Dear Mr. Cartwright, 640 White Avenue Grand Junction, Colorado 81501 Phone: 970-255-8005 Fax: 970-255-6818 Info@huddlestonberry.com April 6, 2017 Project#01641-0002 This letter presents the results of a geotechnical investigation conducted by Huddleston -Berry Engineering & Testing, LLC (HBET) at 38 Snowberry Place in Parachute, Colorado. The site location is shown on Figure 1. The proposed construction is anticipated to consist of a single family residence. The scope of our investigation included evaluating the subsurface conditions at the site to aid in developing foundation recommendations for the proposed construction. Site Conditions At the time of the investigation, the site was open with a moderate slope down to the northwest. Vegetation consisted primarily of weeds and grasses. The site was bordered to the northwest by Snowberry Place, to the northeast and southwest by existing residences, and to the southeast by Monument Trail. Subsurface Investigation The subsurface investigation included two test pits as shown on Figure 2 — Site Plan. Test Pits TP -1 and TP -2 were excavated to depths of 7.5 and 8.0 feet below the existing ground surface, respectively. Typed test pit logs are included in Appendix A. As indicated on the logs, the subsurface conditions at the site were fairly consistent. The test pits generally encountered 1.0 foot of topsoil above tan, moist, medium dense silt with sand above white, moist, very stiff sandy elastic silt to the bottoms of the excavations. Groundwater was not encountered in the test pits at the time of the investigation. 38 Snowberry Place #01641-0002 04/06/17 Huddleston -Berry Fnjln.IngS rEilma.1,1,c Laboratory Testing Laboratory testing was conducted on samples of the native soils encountered in the test pits. The testing included grain size analysis, Atterberg limits determination, natural moisture content determination, and maximum dry density and optimum moisture content (Proctor) determination. The laboratory testing results are included in Appendix B. The laboratory testing results indicate that the native silt with sand soils are slightly plastic. In general, based upon our experience with similar soils in the vicinity of the subject site, the native silt with sand soils are anticipated to be slightly collapsible. The native sandy elastic silt soils were indicated to be highly plastic. Based upon the Atterberg limits of the material, the elastic silt soils are anticipated to be moderately expansive. Foundation Recommendations Based upon the results of the subsurface investigation and nature of the proposed construction, spread footing type foundations are recommended. However, as discussed previously, collapsible and expansive soils were encountered in the subsurface. In general, to limit the potential for excessive differential movements, HBET recommends that the foundations be constructed above a minimum of 24 -inches of structural fill. However, HBET recommends that the foundations be separated from the elastic silt soils a minimum of 48 -inches. As a result, it may be necessary to pothole the foundation area and verify that no elastic silts are present within 48 -inches of the bottoms of the foundations. Where elastic silt soils are encountered within 48 - inches of the bottoms of the foundations, they should be removed and replaced with structural fill. The native silt with sand soils, exclusive of topsoil, are suitable for reuse as structural fill. The native sandy elastic silt soils are not suitable for reuse as structural fill. Imported structural fill should consist of a granular, non -expansive, non -free draining material such as crusher fines or CDOT Class 6 base course. Unless it can be demonstrated that the materials are not free - draining, pit -run materials should not be used as structural fill. Prior to placement of structural fill, it is recommended that the bottom of the foundation excavation be scarified to a depth of 6 to 9 inches, moisture conditioned, and compacted to a minimum of 95% of the standard Proctor maximum dry density, within ± 2% of the optimum moisture content as determined in accordance with ASTM D698. Structural fill should extend laterally beyond the edges of the foundation a distance equal to the thickness of structural fill. Structural fill should be moisture conditioned, placed in maximum 8 -inch loose lifts, and compacted to a minimum of 95% of the standard Proctor maximum dry density for fine grained soils and modified Proctor maximum dry density for coarse grained soils, within ± 2% of the optimum moisture content as determined in accordance with ASTM D698 and D1557C, respectively. X:\2008 ALL PROJECTS\01641 - RC Construction\01641-0002 38 Snowbeny Place\200 - Geo\01641-0002 LR040617.doc 2 38 Snowberry Place #01641-0002 Huddleston -Berry 04/06/17 GorneoIne 3 rwlnr. I.I For structural fill consisting of suitable native soils or imported granular materials and foundation building pad preparation as recommended, a maximum allowable bearing capacity of 2,000 psf is recommended. However, a minimum dead -load pressure of 500 psf is recommended. Where the minimum dead -load is not achievable, such as for interior foundations, the dead -load should be maximized to the extent practical. Any stemwalls, basement walls, or retaining walls should be designed to resist lateral earth pressures. For backfill consisting of the native soils or imported granular, non -free draining, non -expansive material, we recommend that the walls be designed for an active equivalent fluid unit weight of 55 pcf in areas where no surcharge loads are present. An at -rest equivalent fluid unit weight of 75 pcf is recommended for basement or other braced walls. Lateral earth pressures should be increased as necessary to reflect any surcharge loading behind the walls. Water soluble sulfates are common to the soils in Western Colorado. Therefore, at a minimum, Type I-II sulfate resistant cement is recommended for construction at this site. Non -Structural Floor Slab and Exterior Flat -work Recommendations In order to reduce the potential for excessive differential movements, it is recommended that non-structural floating floor slabs be constructed above a minimum of 18 -inches of structural fill with subgrade preparation (including separation from elastic silt soils), structural fill materials, and fill placement be in accordance with the Foundation Recommendations section of this report. It is recommended that exterior flatwork be constructed above subgrade soils, below the topsoil, that have been scarified to a depth of 12 -inches, moisture conditioned, and compacted to a minimum of 95% of the standard Proctor maximum dry density, within ±2% of the optimum moisture content as determined in accordance with ASTM D698. Drainage Recommendations GradittR and drainame are critical for the lona-term performance of the structure and grading around the structure should be designed to carry precipitation and runoff away from the structure. It is recommended that the finished ground surface drop at least twelve inches within the first ten feet away from the structure. It is also recommended that landscaping within five feet of the structure include primarily desert plants with low water requirements. In addition, it is recommended that irrigation within ten feet of foundations be minimized. HBET recommends that downspout extensions be used which discharge a minimum of 5 feet from the structure or beyond the backfill zone, whichever is greater. However, if subsurface downspout drains are utilized, they should be carefully constructed of solid -wall PVC and should daylight a minimum of 15 feet from the structure. In addition, an impermeable membrane is recommended below subsurface downspout drain lines. Dry wells should not be used. As discussed previously, groundwater was not encountered at the site. However, a perimeter foundation drain is recommended to limit the potential for surface moisture to impact the structure. In general, the perimeter foundation drain should consist of prefabricated drain materials or perforated pipe and gravel systems with the flowline of the drain at the bottom of the foundation (at the highest point). The perimeter drain should slope at a minimum of 1% to daylight or to a sump. An impermeable membrane is also recommended at the base of the drain to limit the potential for moisture to infiltrate into the subsurface below the foundations. X:\2008 ALL PROJECTS\01641 - RC Construction\01641-0002 38 Snowberry Place\200 - Geo \01641-0002 LR040617.doc 3 38 Snowberry Place #01641-0002 04/06/17 Huddleston -Berg General Notes The recommendations included above are based upon the results of the subsurface investigation and on our local experience. These conclusions and recommendations are valid only for the proposed construction. As discussed previously, the subsurface conditions at the site were fairly consistent. However, the precise nature and extent of subsurface variability may not become evident until construction. The recommendations contained herein are designed to reduce the risk and magnitude of movements and it is extremely critical that ALL of the recommendations herein be applied to the design and construction. However, HBET cannot predict long-term changes in subsurface moisture conditions and/or the precise magnitude or extent of any volume change in the native soils. Where significant increases in subsurface moisture occur due to poor grading, improper stormwater management, utility line failure, excess irrigation, or other cause, during or after construction, significant movements are possible. In addition, the success of the structure foundations, slabs, etc. is critically dependent upon proper construction. Therefore, HBET should be retained to provide materials testing, special inspections, and engineering oversight during ALL phases of the construction to ensure conformance with the recommendations herein. In addition, any property buyers should be provided a copy of this report and made fully aware of the risks associated with living in an area of moisture sensitive soils. We are pleased to be of service to your project. Please contact us if you have any questions or comments regarding the contents of this report. Respectfully Submitted: Huddleston -Berry Engineering and Testing, LLC Michael A. Berry, P.E. Vice President of Engineering X:\2008 ALL PROJECTS\01641 - RC Construction \01641-0002 38 Snowberry Place\200 - Geo\01641-0002 LR040617.doc 4 FIGURES Garfield County Garfield County Land Explorer Garfield County, Colorado 2 407081 001 52 N,I ,t El %t 240718418028 0 r" 240708100152 North Garfield County Land Explorer Printed by Web User 1 inch = 376 feet 1 inch = 0.07 miles 0.05 0.1 0.2 Miles w Garfield County Garfield County Colorado www,garfleld-coun ty. com Colorado Disclaimer This Ise compilation of records as they appear in the Garfield County Offices effecting the area shown. This drawing is to be used only for reference purposes and the County Is not responsible for any Inaccuracies herein contained. © Copyright Garfield County, Colorado 1 All Rights Reserved Printed: 4/4/2017 at 8:41:42 AM Garfield County Land Explorer Garfield County Garfield County, Colorado 2421.18424011 •240718424013 240718424019 240700100152 240718422011 Garfield County Land Explorer Printed by Web User 1 inch = 94 feet 1 inch = 0.02 miles 0 0125 0.025 FIGURE 2 Site Plan 0-05 Miles Garfield County Garfield County Colorado www.garf leld-county, com Colorado Disclaimer This is a compilation of records as they appear in the Garfield County offices affecting the area shown. This drawing is to be used only for reference purposes and the County Is not responsible for any Inaccuracies herein contained © Copyright Garfield County, Colorado 1 All Rights Reserved Printed; 4/4/2017 at 8:42:30 AM APPENDIX A Typed Test Pit Logs GEOTECH BH COLUMNS 01641-0002 38 SNOVVBERRY PLACE.GPJ GINT US LAB.GDT 416/17 u1 N [n o DEPTH o (ft) GRAPHIC LOG Bottom of test pit at 7.5 feet. Z80 pag!sse}0 gel l9O Pal}issel0 gel SILT with Sand and trace Gravel (ML), tan, moist, medium dense SILT with Sand and Organics (TOPSOIL) NO IldI1:10S301V1H31VA G) m SAMPLE TYPE NUMBER RECOVERY % (RQD) BLOW COUNTS (N VALUE) POCKET PEN. (tsf) DRY UNIT WT. (pcf) MOISTURE CONTENT (%) CO N CO LIQUID LIMIT PLASTIC LIMIT CO PLASTICITY INDEX --1 1— m-1 con m G) rn FINES CONTENT (%) 2 0 m - NOIIVAVOX3 13314V W0 AB 030001 9VIN AB 03)103H0 MP NOILVAVOX3 dO 0N3 IV EXCAVATION METHOD Mini -Excavator MP NOIIVAV3X3 3O BAIL IV EXCAVATION CONTRACTOR Hi -River :S13A31 a31VM ONIlOa0 Ll•/lZ/£ 031mVIS 31V0 03131d11400 NOILVA313 ONfl01:10 3ZIS lld 1531 PROJECT NUMBER 01641-0002 NOI1V001103POad 00 •elnyoeaed uogorulsuo0 0?:1 1N3110 aoeld Auagmoug gE 31MVN 103f Oad E2k;a 3 ry o coen°<W 0c. O m 8 co 3 Dp f0 r- 0 n J J PROJECT NAME 38 Snowberry Place RC Construction Parachute, CO PROJECT LOCATION TEST PIT SIZE GROUND ELEVATION COMPLETED 3/21/17 GROUND WATER LEVELS: O 9 re 0 gN WM m G O v Z O Z ▪ W Xa o a o w AT TIME OF EXCAVATION dry EXCAVATION METHOD Mini -Excavator AT END OF EXCAVATION dry CHECKED BY LOGGED BY CM z re W O z (%) 1N31NO0 S3NId 0 w CO m ck J F X3aNI ALI3IiSVld lIWII 011SVld iIWII anon (%)1N31NO0 321n1SIOW (jod) '1M lINn Alia As;) 'N3d 13>10Od (3nl`dn N) SINno0 MO1E1 4:10 20 % A213AO0321 2138WfN 3dAl 3ldINVS MATERIAL DESCRIPTION and Organics (TOPSOIL) LT with San LT with San 901 01Hdtf2I0 (8) Hld3a 0 ui LL/9/4 la`J'8tll Sl 1NIO rdD30V1d 48U39MONS $£ Z000 -1479L0 SNWl1O0 H8 H031O3O APPENDIX B Laboratory Testing Results ',,: r CLIENT a w 3 0 - y Hudd �°640 WlestonhitAvenue-Berry EngineeringUnitB & Testing, LLC GRAIN SIZE DISTRIBUTION Grand Junction, CO 81501 4- 970-255-8005 `�, 970-255-6818 RC Construction PROJECT NAME 38 Snowberry Place PROJECT NUMBER 01641-0002 PROJECT LOCATION Parachute, CO U.S. SIEVE OPENING IN NCHES 6 4 3 2 1.5 1/24 I U.S. SIEVE NUMBERS I HYDROMETER 1 3 4 6 810 14 16 30 40 60 100140200 100 1 4 j~ f 95 90 85III 80 \\\\ 75 70 65 i- 0 iTi 60 el. m 55 cC z 50 ii t— 45 z w ce 40 w a 35 30 `1 25 • 20 .• 15 10 5 0 100 10 GRAIN SIZE 1 0 1 0.01 0.001 IN MILLIMETERS GRAVEL I SAND OR CLAY COBBLES coarse r fine i coarse medium fine SILT Specimen Identification Classification LL PL PI Cc Cu • TP -1, GB1 3/2017 SILT with SAND(ML) 26 23 3 m TP -1, GB2 3/2017 SANDY ELASTIC SILT(MH) 53 31 22 - Specimen Identification D100 D60 D30 D10 %Gravel %Sand %Silt %Clay • TP -1, GB1 3/2017 9.5 0.8 15.9 83.3 P m TP -1, GB2 3/2017 19 0.088 7.6 36.4 56.1 5 CC CLIENT n„ E: Huddleston -Berry Engineering & Testing, LLC ATTERBERG LIMITS' RESULTS 640 White Avenue, Unit B Grand Junction, CO 81501 970-255-8005 970-255-6818 RC Construction PROJECT NAME 38 Snowberry Place PROJECT NUMBER 01641-0002 PROJECT LOCATION Parachute, CO 60 OF CH 50 P L A s 40 T 1 C T 30 Y I 1 N 20 D E X 10 CL -ML CIMH 0 - 3 20 40 60 80 100 LIQUID LIMIT Specimen Identification LL PL PI #200 Classification • TP -1, GB1 3/2017 26 23 3 83 SILT with SAND(ML) m TP -1, GB2 3/2017 53 31 22 56 SANDY ELASTIC SILT(MH) CLIENT PROJECT Z °pit Huddleston -Berry Engineering & Testing, LLC `.° 640 White Avenue, Unit B Grand Junction, CO 81501 0 970-255-8005 • et''' 970-255-6818 RC Construction PROJECT MOISTURE NAME LOCATION -DENSITY 38 Snowberry Place RELATIONSHIP NUMBER 01641-0002 PROJECT _._Parachute, CO 150 \ Sample Date: 3/21/2017 \\\ 17-0150 Sample No.: i Source of Material: TP -1 145 \ 111, Material: SILT with SAND(ML) \ Description of Test Method: ASTM D698A U w c) o 140 135\\TEST 130 125 120 115 110 105 900 Maximum Optimum Dry Water Density Content GRADATION ##2004 RESULTS ATTERBERG RESULTS Curves for \ 110.0 PCF % (% LIMITS 100% Gravity 2.80 2.70 2.60 PASSING) 3/4" \ 14.0 99 PL \ \ 83 LL 100 \ PI to: \� \ \ 26 23 Specific of 3 Saturation Equal \\* � � \ \ \\:\100 \\\95 5 10 15 20 25 30 WATER CONTENT, % U