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HomeMy WebLinkAboutCC - Geotech Report CMTENGINEERING L A B O R A T O R I E S -70 JIM AL o 0 z PRELIMINARY GEOTECHNICAL G, n m Z ENGINEERING STUDY Z z 22 m m m = N Z 0 -1 Maslonka Property r E N • x 6) O = NE Corner of Linder Road and Amity Road < n n Boise, Idaho E r- r- CMT PROJECT NO. 13175 m Z m < n 30 FOR: N • m DevCo, LLC r- Laren M. Bailey,MCRP, PMP m D September 12, 2019 CMTENGINEERING L A B O R A T O R I E S September 12, 2019 DevCo LLC Attn: Laren Bailey Subject: Preliminary Geotechnical Engineering Study Maslonka Property NE Corner of Linder and Amity Boise, Idaho CMT Project No. 13175 Mr. Bailey: Submitted herewith is our preliminary geotechnical engineering study for the subject site. This report contains the results of our findings with respect to the available project characteristics. On August 23, 2019, a CMT Engineering Laboratories (CMT) engineer was on-site and supervised the excavation of 4 test pits extending to a depth of about 10 feet below the existing ground surface. Soil samples were obtained during the field operations and subsequently transported to our laboratory for further testing and observation. We appreciate the opportunity to work with you at this stage of the project. CMT offers a full range of Geotechnical Engineering, Geological, Material Testing, Special Inspection services, and Phase I and II Environmental Site Assessments. With 9 offices throughout Utah, Idaho and Arizona, our staff is capable of efficiently serving your project needs. If we can be of further assistance or if you have any questions regarding this project, please do not hesitate to contact us at (208) 912-1868. Sincerely, CMT Engineering Laboratories Reviewed by: N 1 A -- Phillip Pack, P.E. Greg Mugavero Senior Geotechnical Engineer Regional Manager ENGINEERING• GEOTECHNICAL• ENVIRONMENTAL (ESA I & II)• MATERIALS TESTING• SPECIAL INSPECTIONS ORGANIC CHEMISTRY • PAVEMENT DESIGN• GEOLOGY www.cmtlaboratories.com CMTENGINEERING L A B O R A T O R I E S TABLE OF CONTENTS 1.0 INTRODUCTION............................................................................................................................................................3 1.1 General ...................................................................................................................................................................................3 1.2 Objectives, Scope and Authorization......................................................................................................................................4 2.0 FIELD EXPLORATION.....................................................................................................................................................4 2.1 General ...................................................................................................................................................................................4 3.0 LABORATORY TESTING.................................................................................................................................................5 4.0 SITE CONDITIONS.........................................................................................................................................................5 4.1 Surface Conditions..................................................................................................................................................................5 4.2 Subsurface Soils......................................................................................................................................................................5 4.3 Groundwater ..........................................................................................................................................................................6 4.4 Site Subsurface Variations......................................................................................................................................................6 5.0 LIMITATIONS ...............................................................................................................................................................6 APPENDIX Figure 1:Site Plan Figures 2-5:Test Pit Logs Figure 6: Key to Symbols Preliminary Geotechnical Engineering Study Page 3 Maslonka Property—Boise, Idaho CMT Project No. 13175 1.0 INTRODUCTION 1.1 General CMT Engineering Laboratories (CMT) was retained to conduct a preliminary geotechnical subsurface study for the proposed development of a residential subdivision. The parcel is situated on the NE corner of Amity Road and Linder Road in Boise, Idaho, as shown in the Vicinity Map below. SITEZ. AI- ?� . . . ti ra � 5 -W."Z am i e VICINITY MAP CmTENGINEERING Preliminary Geotechnical Engineering Study Page 4 Maslonka Property—Boise, Idaho CMT Project No. 13175 1.2 Objectives, Scope and Authorization The objectives and scope of our study were planned in discussions between Mr. Laren Bailey of DevCo LLC and Phillip Pack of CMT Engineering Laboratories (CMT). In general, the objectives of this study were to define and evaluate the subsurface soil and groundwater conditions at the site. In accomplishing these objectives, our scope of work has included performing field exploration, which consisted of the excavating/logging/sampling of 4 test pits, and performing laboratory testing on representative samples. This scope of work was authorized by returning a signed copy of our proposal dated August 8-2019. 2.0 FIELD EXPLORATION 2.1 General In order to define and evaluate the subsurface soil and groundwater conditions at the site, 4 test pits were excavated with a backhoe at the site to a depth of approximately 10 feet below the existing ground surface. Locations of the test pits are shown on Figure 1, Site Plan, included in the Appendix. The field exploration was performed under the supervision of an experienced member of our geotechnical staff. Representative soil samples were collected by obtaining disturbed "grab" samples and cutting relatively undisturbed "block" samples from within each test pit. The samples were placed in sealed plastic bags and containers prior to transport to the laboratory. The subsurface soils encountered in the test pits were logged and described in general accordance with ASTM1 D-2488. Soil samples were collected as described above, and were classified in the field based upon visual and textural examination. These field classifications were supplemented by subsequent examination and testing of select samples in our laboratory. Graphical representations of the subsurface conditions encountered are presented on each individual Test Pit Log, Figures 2 through 5, included in the Appendix. A Key to Symbols defining the terms and symbols used on the logs, is provided as Figure 6 in the Appendix. When backfilling the test pits, only minimal effort was made to compact the backfill and no compaction testing was performed. Thus, settlement of the backfill in the test pits over time should be anticipated. 'American Society for Testing and Materials CmTENGINEERING Preliminary Geotechnical Engineering Study Page 5 Maslonka Property—Boise, Idaho CMT Project No. 13175 3.0 LABORATORY TESTING Selected samples of the subsurface soils were subjected to various laboratory tests to assess pertinent engineering properties, as follows: 1. Moisture Content, ASTM D-2216, Percent moisture representative of field conditions 2. Atterberg Limits, ASTM D-4318, Plasticity and workability 3. Gradation Analysis, ASTM D-1140/C-117, Grain Size Analysis Laboratory test results are presented on the test pit logs (Figures 2 through 5) and in the attached Appendix. 4.0 SITE CONDITIONS 4.1 Surface Conditions At the time the test pits were excavated the site consisted of two adjacent fields vegetated with grain and some grasses and weeds. The site grade sloped downward to the south with an overall gradient of about 5 to 10 feet. Based upon aerial photos readily available online dating back to 1993, the site appears to have been fields since that time. The site is bounded on the south by Amity Road and on the west by Linder Road (see Vicinity Map in Section 1.1 above). 4.2 Subsurface Soils At the locations of the test pits we encountered approximately 4 to 6 inches of topsoil at the surface. Natural soils were observed beneath the topsoil/fill soils, consisting of light brown SILT (ML) with caliche extending to depths of about 5 to 6 feet below the surface. Natural, light brown coarse SAND (SP) with gravel and cobbles was encountered extending to the full depth penetrated, 10 feet. The silt soils were slightly moist brown in color, and estimated to be medium stiff in consistency. The natural sand soils were moist, brown in color, and estimated to be medium dense to dense. For a more descriptive interpretation of subsurface conditions, please refer to the test pit logs, Figures 2 through 5, which graphically represent the subsurface conditions encountered. The lines designating the interface between soil types on the logs generally represent approximate boundaries - in situ, the transition between soil types may be gradual. CmTENGINEERING Preliminary Geotechnical Engineering Study Page 6 Maslonka Property—Boise, Idaho CMT Project No. 13175 4.3 Groundwater Groundwater was not encountered at the time of our field explorations within the maximum depth explored of about 10 feet below the existing ground surface. Therefore, groundwater is not anticipated to affect proposed construction. Groundwater levels can fluctuate as much as 1.5 to 2 feet seasonally. Numerous other factors such as heavy precipitation, irrigation of neighboring land, and other unforeseen factors, may also influence ground water elevations at the site. The detailed evaluation of these and other factors, which may be responsible for ground water fluctuations, is beyond the scope of this study. 4.4 Site Subsurface Variations Based on the results of the subsurface explorations and our experience, variations in the continuity and nature of subsurface conditions should be anticipated. Due to the heterogeneous characteristics of natural soils, care should be taken in interpolating or extrapolating subsurface conditions between or beyond the exploratory locations. Also, when logging and sampling of the test pits was completed, the test pits were backfilled with the excavated soils but minimal to no effort was made to compact these soils. Thus, settlement of the backfill in the test pits over time should be anticipated. 5.0 LIMITATIONS The recommendations provided herein were developed by evaluating the information obtained from the subsurface explorations and soils encountered therein. The exploration logs reflect the subsurface conditions only at the specific location at the particular time designated on the logs. Soil and ground water conditions may differ from conditions encountered at the actual exploration locations. The nature and extent of any variation in the explorations may not become evident until during the course of construction. If variations do appear, it may become necessary to re-evaluate the recommendations of this report after we have observed the variation. Our professional services have been performed, our findings obtained, and our recommendations prepared in accordance with generally accepted geotechnical engineering principles and practices. This warranty is in lieu of all other warranties, either expressed or implied. We appreciate the opportunity to be of service to you on this project. If we can be of further assistance or if you have any questions regarding this project, please do not hesitate to contact us at (208) 912-1868 CM TL A 8 0 R A i 0 R 1 E 5 APPENDIX SUPPORTING DOCUMENTATION CMTENGINEERING i4 TP-1 - TP-2 S4 r. TP-4 r -- Maslonka Property CMTENGINEERING Figure: L A B O R A T O R I E 5 Northeast Corner of Linder Road and Amity Road Site Plan ate: 0-Jan-00 Date: # 13175 Maslonka Property Test Pit Log TP-1 NE Corner Amity& Linder Equipment: Rubber Tire Backhoe Total Depth: 10' Date: 8/23/19 Surface Elev.(approx): Water Depth: (see Remy ks) Job#: 13175 Q Gradation Atterberg a o a o Soil Description o J EE ma Q) i L< cD CO L a a 0 TOPSOIL, brown silt with vegetation Light Brown SILT(ML),with caliche 2 grades to cemented caliche hard 4 6 •• Light Brown Coarse SAND(SP),with gravel and cobbles 8 10 END AT 10' 12 14 16 18 20 22 24 26 28 Remarks: Groundwater not encountered during excavation. Figure: Excavated By: Inselman Excavation C7M=17ENGINEERING Logged By: Lou Watts L A B O R A T d R 1 ES 2 Page: 1 of 1 Maslonka Property Test Pit Log TP-2 NE Corner Amity& Linder Equipment: Rubber Tire Backhoe Total Depth: 11' Date: 8/23/19 Surface Elev.(approx): Water Depth: (see Remy ks) Job#: 13175 Q Gradation Atterberg a o a o Soil Description o J EE ma Q) i L< cD CO L a a 0 TOPSOIL, brown silty sand with vegetation Light Brown SILT(ML),with caliche 2 • Light Brown Coarse SAND(SP),with gravel and cobbles 4 6 8 grades with fine to medium sand 10 END AT 11' 12 14 16 18 20 22 24 26 28 Remarks: Groundwater not encountered during excavation. Figure: Excavated By: Inselman Excavation C7M=17ENGINEERING Logged By: Lou Watts L A B O R A T d R 1 ES 3 Page: 1 of 1 Maslonka Property Test Pit Log TP-3 NE Corner Amity& Linder Equipment: Rubber Tire Backhoe Total Depth: 10' Date: 8/23/19 Surface Elev.(approx): Water Depth: (see Remy ks) Job#: 13175 Gradation Atterberg a o Soil Description o J EE ma Q) i L< CO L a a 0 Brown Silty SAND(SM) 2 grades with caliche 4 grades to cemented caliche 6 •• Light Brown Medium to Coarse SAND(SP),with gravel and cobbles 8 10 END AT 10' 12 14 16 18 20 22 24 26 28 Remarks: Groundwater not encountered during excavation. Figure: Excavated By: Inselman Excavation C7M=17ENGINEERING Logged By: Lou Watts L A B O R A T d R 1 ES 4 Page: 1 of 1 Maslonka Property Test Pit Log TP-4 NE Corner Amity& Linder Equipment: Rubber Tire Backhoe Total Depth: 6.5' Date: 8/23/19 Surface Elev.(approx): Water Depth: (see Remy ks) Job#: 13175 Gradatior Atterberg U a 8-1 a o Soil Description _ o o f c� E a E 6 coL6 � C_ J _ n U) Cn LL 0 TOPSOIL, brown clayey sand with vegetation Brown Clayey SAND(SC) 2 Brown Medium SAND(SP),with caliche 4 grades with medium to coarse sand 6 grades to cemented caliche REFUSAL AT 6.5' 8 10 12 14 16 18 20 22 24 26 28 Remarks: Groundwater not encountered during excavation. Figure: Excavated By: Inselman Excavation C:M7=ENG1NEER1NG Logged By: Lou Watts L A B d R A T d R I E 5 Page: 1 of 1 Maslonka Property Key to Symbols (enter location) Date:arrer Excavati( Job#: 13175 Gradation Atterberg ® O Soil Description CLe T c t a a Q. a Q E E o Z m c c o to c 0 to E J a a 4) C3) COLUMN DESCRIPTIONS O Depth(ft.):Depth(feet)below the ground surface(including O Atterberci: Individual descriptions of Atterberg Tests are as follows: groundwater depth-see water symbol below). 2 Graphic Loci:Graphic depicting type of soil encountered ILL=Liquid Limit(!/ Water content at which a soil changes from 4) (see( below). plastic to liquid behavior. O Soil Description: Description of soils encountered,including PL=Plastic Limit(%):Water content at which a soil changes from liquid Unified Soil Classification Symbol(see below). to plastic behavior. ® Sample Type:Type of soil sample collected at depth interval PI=Plasticity Index(%): Range of water content at which a soil exhibits shown;sampler symbols are explained below-right. plastic properties(=Liquid Limit-Plastic Limit). O Sample#:Consecutive numbering of soil samples collected during field exploration. STRATIFICATION MODIFIERS MOISTURE CONTENT Moisture(%):Water content of soil sample measured in Description Thickness Trace © laboratory(percentage of dry weight of sample). Seam Up to%inch <5% moisture,dusty,dry to O Dry Density(pcf):The dry density of a soil measured in Lense Up to 12 inches Some Moist:Damp/moist to laboratory(pounds per cubic foot). Layer Greater than 12 in. 5-12% the touch,but no visible Gradation:Percentages of Gravel,Sand and Fines Occasional 1 or less per foot With water. ® (Silt/Clay),obtained from lab test results of soil passing the Frequent I More than 1 per foot I >12% Saturated:Visible water, No.4 and No.200 sieves. usually soil below groundwater. MAJOR DIVISIONS USCS O TYPICAL DESCRIPTIONS SYMBOLS CLEAN Well-Graded Gravels,Gravel-Sand Mixtures,Little or SAMPLER GRAVELS GW - No Fines SYMBOLS (� GRAVELS o Poorly-Graded Gravels,Gravel-Sand Mixtures,Little CO) The coarse (<5%fines) - or No Fines Block Sample fraction P GRAVELS WITH G � COARSE- retained on FINES GM Silty Gravels,Gravel-Sand-Silt Mixtures W GRAINED No.4 sieve. Bulk/Bag Sample F- SOILS ('-12%fines) GC Clayey Gravels,Gravel-Sand-Clay Mixtures Modified California >- More than 50% CLEAN SANDS SW • Well-Graded Sands,Gravelly Sands,Little or No B Sampler of material is SANDS Fines m 3.5"OD,2.42"ID (<5% Z larger than No. The coarse o fines) S P •• Poorly-Graded Sands,Gravelly Sands,Little or No D&M Sampler O 200 sieve size. m fraction Fines passing SANDS WITH Rock Core Q through FINES SM Silty Sands,Sand-Silt Mixtures Standard U No.4 sieve. a Penetration Split LL (>_12%fines) SC Clayey Sands,Sand-Clay Mixtures Spoon Sampler Inorganic Silts and Sandy Silts with No Plasticity or ® Thin Wall a M L Clayey Silts with Slight Plasticity (Shelby Tube) V FINE- SILTS AND CLAYS CL Inorganic Clays of Low to Medium Plasticity,Gravelly J GRAINED Liquid Limit less than 50% Clays,Sandy Clays,Silty Clays,Lean Clays SOILS OL �, Organic Silts and Organic Silty Clays of Low Plasticity More than 50% Inorganic Silts,Micacious or Diatomacious Fine Sand Wof material is M H or Silty Soils WATER SYMBOL smaller than No. SILTS AND CLAYS LL CHInorganic Clays of High Plasticity,Fat Clays Z 200 sieve size. Liquid Limit greater than 50% � Encountered Water OH Organic Silts and Organic Clays of Medium to High - Level 1`` Plasticity = Measured Water HIGHLY ORGANIC SOILS PT Peat,Soils with High Organic Contents Level (see Remarks on Logs) Note:Dual Symbols are used to indicate borderline soil classifications(i.e.GP-GM,SC-SM,etc.). 1.The results of laboratory tests on the samples collected are shown on the logs at the respective sample depths. Figure: 2.The subsurface conditions represented on the logs are for the locations specified.Caution should be exercised if interpolating between or extrapolating beyond the exploration locations. 3.The information presented on each log is subject to the limitations,conclusions,and recommendations presented in this report. CMTENGINEERING