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Home My WebLink AboutSoils Report 05.15.2019RECEIVED GEOLOGIC REVIEW AND SOILS ENGINEERING REPORT 223 Eagle Ridge Drive Parachute, CO AUG 0 2 2019 GARFIELD COUNTY COMMUNITY DEVELOPMENT Prepared For: Wade Wiggins Prepared By CAPSTONE ' ENTERPRISES WEST, L � GEOTECHNICAL AND MINING ENGINEERING TESTING AND INSPECTION SERVICES 618 PARTEE DRIVE GRAND JUNCTION, CO 81504 PHONE (970) 250-3331 martin@capstonewest.com May 15, 2019 Job No. 4396 CAPSTONE-�sn_: 2ascsa ENTERPRISES WEST, LLC GEOTECHNICAL AND MINING ENGINEERING TESTING AND INSPECTION SERVICES 618 PARTEE DRIVE GRAND JUNCTION, CO 81501. PHONE (970) 250-3331 martin@ca pstonewest.co m May 15, 2019 JOB # 4396 Attention: Wade Wiggins Grand Junction, CO Subject: Geologic Review and Soils Engineering Report 223 Eagle Ridge Drive Parachute, CO 81635 As per the request, Capstone Enterprises West, LLC (Capstone) performed a site specific geotechnical investigation of the aforementioned parcel. The purpose of this work is to make foundation recommendations for the construction of a new home at the site. SITE LOCATION The property is a 0.29 parcel located on the the section line between sections 16 &17 T7S R97W. The following image shows the general location. SITE DESCRIPTION The site was previously grazing land, prior to the development to the Battlement Mesa Golf Community. The property slopes gradually to the south. CAPSTONE ENTERPRISES 4396 2 r .i•'ri ` 4 "rrur�roe[wl i r .r • r+ara' m, -;t• '......4..14 ..:. :...p. .'rri =_7ti her.: i.: --77:!1' i`fh Irprx i:1. 1 • ;� :kssaHro 1 s • 'Site Location f [ .- k J '. ^,/n-'`. �.._. • `Y iNlli[f1911 f ':'=�:;: .i:• �:eletil/n41AI ry�S,t 7._...._. :lit km:IHith—"Ai, %,...:;......:,,,—;.4.,:.,,,....1.,_{.....,....",..u.,,..!..- .IyS'-t: Ir .tit F y .:nrmrn 1 tirmrlef«cr 1 1r• sy $n1,I,�Knr i 1.V41111.lert GEOLOGIC DESCRIPTION Bedrock in the area has been mapped as Wasatch Formation (Tws and Twm). However, the bedrock is covered with a layer of alluvial/colluvial mudflows mapped as the Lands End Formation (Qla). A portion of the USGS Geologic Map of the DeBeque Quadrangle shows the regional geology of the site. Qa Ic QoJ CAPSTONE ENTERPRISES 4396 Site Location 0 l Qgmt .7/25Ta if illi T: ii,;:1S f :CP di 6113 E,i n op:fe•3I1 Cli LI:•ayrit '±ri;e 10 rJn ..ITei deyy�i:lN••Gr:.l;�.;e,p,+ Y.•M 9rlrel 6f bice': els 71:4!lf ierlfid iy9i/. 11t %4b!SSST7i 1.71.rllflr [; war./ M1.r!'Nf: fR•:r1) M11 I II'4 1 rl[ fr,+ri1+,4 41,01r 1 ee71 nt ,r«i. 71lrrn Ihivklgll :X, It '1}.r_. Ogmt • • The following map shows the National Resources Conservation Service's breakdown of surface soil types in the area. Rifle Area, Colorado, Parts of Garfield and Mesa Counties 56—Potts loam, 6 to 12 percent slopes Map Unit Setting National map unit symbol: jnys Elevation: 5,000 to 7,000 feet Farmland classification: Farmland of statewide importance Map Unit Composition • Potts and similar soils: 85 percent • Estimates are based on observations, descriptions, and transects of the mapunit. Description of Potts Setting • Landform: Valley sides, benches, mesas Down-slope shape: Convex, linear • Across -slope shape: Convex, linear CAPSTONE ENTERPRISES 4396 4 • Parent material: Alluvium derived from basalt and/or alluvium derived from sandstone and shale Typical profile • Hi - 0 to 4 inches: foam • H2 - 4 to 28 inches: clay loam • H3 - 28 to 60 inches: loam Properties and qualities • Slope: 6 to 12 percent • Depth to restrictive feature: More than 80 inches • Natural drainage class: Well drained • Runoff class: High • Capacity of the most limiting layer to transmit water (Ksat): Moderately high (0.20 to 0.60 in/hr) • Depth to water table: More than 80 inches • Frequency of flooding: None • Frequency of ponding: None • Calcium carbonate, maximum in profile: 15 percent • Salinity, maximum in profile: Nonsaline to very slightly saline (0.0 to 2.0 mmhos/cm) • Available water storage in profile: High (about 10.3 inches) Interpretive groups Land capability classification (irrigated): 4e • Land capability classification (nonirrigated): 4e • Hydrologic Soil Group: C • Ecological site: Rolling Loam (R048AY298C0) Hydric soil rating: No SUBSURFACE INVESTIGATIONS Two test pits were excavated on the site. The location is presented on the following image. The geology of the excavations is presented on the following page. GROUNDWATER No free groundwater was encountered in the test pits. Nor was there evidence of a seasonal high-water table. CAPSTONE ENTERPRISES 4396 5 lz 1 `• • 1 .HR)I I1itP74 a!o1«^w► ' r t amltupm:' 4.6 • 2.1071011111.9 (111:11e17 1 r TP -1 71D712.111U14 • .• • ifi'nife5aj�Y 7., } 2407/7210,1 :. • ! w— ••: f .'Id11125101 Of _ >� a 1 - 216717:1117A • TEST PIT GEOLOGY TP -2 Topsoil- Silt w/ Roots Red -Brown Silt w/ Gravel PI=5 Dry Density = 97.0 pcf- Moisture cfMoisture = 10.1% Tan Silt w/ Gravel PI = 22 Dry Density = 83.3 pcf I Moisture = 14.7% Cobbles in Tan Silt Matrix Topsoil- Silt w/ Roots Red -Brown Silt w/ Gravel PI = 5 ry Density = 97.7 pcf Moisture = 13.1% Tan Silt w/ Gravel PI = 22 Cobbles in Tan Silt Matrix LABORATORY RESULTS The suitability for foundation material is generally determined by two tests: the Swell/Consolidation test and the Atterberg Limits test. The Swell/Consolidation test consists of placing an undisturbed sample of material in a device that applies CAPSTONE ENTERPRISES 4396 6 a Toad to the soil. The specimen compacts or "consolidates". After the initial load stabilizes, the specimen is saturated, and the specimen will either swell or consolidate further. The test results for the samples from the test pit are presented below and on the following page. TP -1 at 2 ft 0.00% 100 -1.00% -Z00% -3.00% x{.00% -5.00% -6.00% -7.00% -8.00% -9.00% -10.00% PERCENT STRAIN CONSOLIDATION TEST REPORT WAT ER AD i DEO 0000 Job No.4396 Parachute Job Number Sample Source Sample Description Natural Dry Density Natural Moisture Content Saturated Moisture Content APPLIED PRESSURE - psf Job No.4396 Parachute TP -1 at 2 ft Red Silt 97.0 pcf 89% Relative Compaction 10.1% -6.1% From Optimum 26.0% CAPSTONE ENTERPRISES 4396 7 PERCENT STRAIN TP -1 at 4 ft 0.00%+ 1C -1.00% -2.00% -3.00% -4.00% -5.00% -6.00% -7.00% -8.00% -9.00% -1 0.00% CONSOLIDATION TEST REPORT 0 r WATER, ADC IED,'/ Job No.4398 Parachute APPLIED PRESSURE - psf Job Number Sample Source Sample Description Natural Dry Density Natural Moisture Content Job No.4396 Parachute TP -1 at4ft Tan Slit 83.3 pcf 14.7% CAPSTONE ENTERPRISES 4396 8 TP -2 at 2 ft —1.00% -2.00% -3.00% -4.00% -5.00% su -6.00% -7.00% -8.00% -9.00% -10.00% CONSOLIDATION TEST REPORT c0 WA -ER ADDED Jeb No.4396 Parachute APPLIED PRESSURE- psf Job Number Sample Source Sample Description Natural Dry Density Natural Moisture Content Job No.4396 Parachute TP -2 at 2 ft Red Silt 103.1 pcf 94% Relative Compaction 13.1% -3.1% From Optimum These consolidation tests show that the dry soils will consolidate when saturated and the well compacted soils will swell slightly when saturated. The Atterberg Limits Test gives an indication of the mechanical properties of fine grained materials. The first part of the test is to determine the Plastic Limit of the material. Then the Liquid Limit is determined. The difference between the Liquid Limit and the Plastic Limit is defined as the Plasticity Index. Swell potential based on the plasticity limit (PI) are shown below. CAPSTONE ENTERPRISES 4396 9 Plasticity Index (PI) Inherent Swelling Capacity 0-15 Low 10-35 Medium 20-55 High 35+ Very High (After Seed et al. 1962) The results of the bulk samples taken from the test pits TP -1 and TP -2 between 1 and 3 feet below the surface indicated the material had low plasticity, indicating there is a low swelling potential. The tan silt sample had a PI of 22; however, it falls into the silt category due to the high plastic limit. Material Source Depth Liquid Limit Plastic Limit Plasticity Index Red -Brown Silt TP -1&2 1-3 ft 28 23 5 Tan Silt TP -1&2 3-5 ft 55 33 22 70 60 50 to 40 x 20 10 0 0 UNIFIED SOIL CLASSIFICATION CHART 20 Job No.4396 Parachute 40 60 LfQUWD LIMIT (LL) 80 100 CAPSTONE ENTERPRISES 4396 la o Tf•182FromTlo$-RCJ19n to 4 TP•182 From 9•lo6 -Tan Sil CH ALINE CL CLAY (') /SILSIL 1 (M) MH OR CL -ML M ML0tOL 20 Job No.4396 Parachute 40 60 LfQUWD LIMIT (LL) 80 100 CAPSTONE ENTERPRISES 4396 la 1 determine the relative compaction of the native state, a Standard Proctor test was performed on a TP -1 and TP -2 composite bulk sample from 1 to 3 feet below the surface. The results are presented below. Wade Wiggins Parachute Job No.4396 120.0 118.0 116.0 cd 110.0 108.0 106.0 104.0 102.0 MOISTURE -DENSITY RELATION (ASTM D-698) Reddish Silt 109.4 pcf @ 16.2%MOISTURE 100.0 10% 12% 14% 16% 18% 20% 22% 24% MOISTURE CONTENT % CAPSTONE ENTERPRISES 4396 J.J. DESIGN CONCERNS The materials were very similar in both test pits, with the reddish brown silt at the foundation elevation. The surface soils were moderately dry. The dry soils are prone to collapse when saturated. Therefore, the depth of moisture conditioning should be deep enough to mitigate this risk. The tan silt had a PI of 22 indicating moderate swell potential; however, the native sample showed consolidation when saturated and very little rebound in the swell/consolidation test. FOUNDATION RECOMMENDATIONS Based on the amount of consolidation observed, Capstone recommends the structure be built on a stemwall and footer system. The maximum bearing Toad The material below the footer shall be compacted to greater than 95% of the Standard Proctor at +/- 2% of optimum moisture content. The should be 1,250 psf. compacted area shall extend a minimum of 2 feet beyond the actual foundation limits, The depth of subgrade compaction should be a minimum of 2 feet. The following sketches show the general arrangements. Essentially, the topsoil with the abundant roots is removed and the foundation is built 1 foot below the existing ground. Landscape Backfill +92% Compaction at or above Opt MC Native Backfill +95% Compaction +/- 2% Opt MC Subgrade Moisture Conditioned and Compacted +95% Compaction -0/+2 Opt MC EXCAVATION Capstone personnel should be contracted to observe the excavation to assess the subgrade and make any changes if warranted. The foundation envelope should be CAPSTONE ENTERPRISES 4396 12 cleared of the topsoil containing abundant roots (approximately 12" minimum). The foundation envelope should extend a minimum of 2 feet beyond the actual foundation limits (including any pads isolated from the stemwall). This material may be used for backfilling around the foundation and surface grading away from the house. COMPACTED MAT In order to minimize the risk of differential settlement, Capstone recommends that the footprint of the house be moisture conditioned to consolidate the poorly consolidated native soils. ibis moisture conditioning should be to a minimum of 2 feet below the foundation. One foot should be removed from the foundation envelope (and processed to uniform moisture and texture), then the envelope area should be scarified 6 to 8 inches deep and moisture conditioned. Ideally this moisture conditioning would be done toward the end of the day to allow the moisture to soak in overnight. Frozen material shall never be placed within the foundation envelope. The scarified and moisture condition subgrade should be compacted to a minimum of 95% of the maximum dry density at a moisture content +/- 2% of optimum. Once that is achieved, the material removed from the envelope can be moisture conditioned and replaced, being compacted to the same 95% specification. SLAB CONSTRUCTION To minimize the risk of driveway and patio distress, the subgrade below them should be moisture conditioned and compacted a minimum of 1 foot deep. DRAINAGE AND IRRIGATION The success of shallow foundation and slab -on -grade floor systems is contingent upon keeping the sub grade soils at more or less constant moisture content, and by not allowing surface drainage a path to the subsurface. Positive surface drainage away from the structures must be maintained at all times (including construction). Landscaped areas should be designed and built such that CAPSTONE ENTERPRISES 4396 13 irrigation and other surface water will be collected and carried away from foundation elements. The final grade of the foundation's backfill and any overlying concrete slabs or sidewalks should have a positive slope away from the foundation walls on all sides. We recommend a minimum slope of 10" in the first ten feet; however, the slope can be decreased to 3" in ten feet if the ground surface adjacent to the foundation is covered with concrete slabs sidewalks or pavement. • As much as practical, we recommend, landscaping vegetation that is common to semi -arid climates, with low moisture requirements. A "drip" system of watering could be utilized to keep water usage low. Dry -type landscaping is encouraged. • Areas close to foundation elements, where snow will drift and accumulate, should be protected from standing water during periods of snowmelt. • Landscaped areas should be placed away from the foundation elements, and be designed to drain surface runoff away from the foundation elements. • The structure should have a rain gutter system that directs water well away from the foundation elements. • To reduce the permeability of the backfill around the foundation, it should be moisture conditioned and compacted as soon as practical. LIMITATIONS The analysis and recommendations submitted in this report are based on the test pit excavations field observations and laboratory testing. The nature and extent of variation may not become evident until construction. If variations then appear, it will be necessary to reevaluate the recommendations in this report. It is recommended that the geotechnical engineer be provided the opportunity for general review of the final design and specifications inorder that earthwork and foundation recommendations may be properly interpreted and implemented in the design and specifications. it is also recommended that the geotechnical engineer, or a qualified geo-technician under his supervision, be retained to provide CAPSTONE ENTERPRISES 4396 14 continuous engineering services during construction of the foundation, excavations, and earthwork phases of the work. This is to observe compliance with the design concepts, specifications, or recommendations and to modify these recommendations in the event that subsurface conditions differ from those anticipated. The recommendations contained in this report are made in a manner consistent with the level of care and skill used by geotechnical engineers practicing in this area at this time. This report contains no warranty either express or implied. If you have any questions, or if we may be of further assistance, please do not hesitate to contact us. Respectfully Submitted: CAPSTONE ENTERPRISES WEST, LLC Martin W. Chenoweth, PE Registered Professional Engineer MWC CAPSTONE ENTERPRISES 4396 15