GEOTECHNICAL INVESTIGATION

Transcription

1 GEOTECHNICAL INVESTIGATION FOR JEFFERSON COUNTY COURTHOUSE RIGBY, IDAHO PREPARED BY

2 Table of Contents 1.0 Executive Summary Introduction Purpose and Detailed Scope-of-Service Project Description Limitations, Exceptions, and User Reliance Site Description Site Location and Current Property Use Descriptions of Structures, Roads, Other On-Site Improvements Site Geology Seismicity Field Exploration Exploration Summary Exploration Procedures Lab Testing Supplemental Information Subsurface Soils Groundwater Table Foundation Recommendations Bearing Capacity Structural Fill and Foundation Considerations Structural Fill and Foundation Considerations Site Preparation, Compacted Fill Requirements and Pavement Design Site Preparation Foundation, Floor Slab, and Pavement Areas Wet Weather Construction Pavement Design Conclusions APPENDICES Appendix A - Appendix B - Appendix C - Vicinity Map, Test Hole Map, Photos, Soil Logs, Log Data and USDA Soil Survey ASFE Report HLE, Inc. Page 1

3 1.0 Executive Summary The executive summary provides a brief report of the results of our site investigation, field and laboratory tests, and our analysis and recommendations. This is only a summary and should be read in conjunction with the entire report for correct interpretation of the overall investigation. Based on the data obtained from the borings and laboratory tests, it is our opinion that the site is suitable for support of the proposed structures as is. It is recommended to re-compact the existing poorly graded gravel with sand/silt (GP/GM) to a minimum of 92% of the maximum density as of a ASTM D If 92% of maximum dry density cannot be achieved, then three (3 ) feet of the native soil should be over-excavated and replaced with TensarTriAX TX160geo grid and three (3 ) feet of compacted structural fill. All top soil should be excavated removing all organic material. Groundwater Conditions: Groundwater was not encountered in any of the test holes during excavation or after excavation. Hydrologic data suggests groundwater depths of feet in the area. HLE did not observe any indications, such as mottling of the soils that would suggest that seasonal groundwater levels exist within the depths explored. Subsurface Soils: TABLE 1-SUBSURFACE SOILS Soil Classification Test Pits Encountered Depths Encountered Net Allowable Bearing Capacity(FS=3) Sod over Sandy Silt feet N/A Poorly Graded Gravel 1, 2, 4, 5, feet lbs/ft² with Sand Silty Sand feet N/A Poorly Graded Gravel feet 3,300 lbs/ft² with Sand and Silt Building Foundations: Based on the data obtained from the borings and laboratory tests, it is our opinion that the site is suitable for support of the proposed structures as is. It is recommended to recompact the existing poorly graded gravel with sand/silt (GP/GM) to a minimum of 92% of the maximum density as of a ASTM D If 92% of maximum dry density cannot be achieved, then three (3 ) feet of the native soil should be over-excavated and replaced with TensarTriAX TX160geo grid and three (3 ) feet of compacted structural fill. All top soil should be excavated removing all organic material. Any structural fill shall be in accordance with the structural fill portion of this report and be compacted to a minimum 95% of the maximum density as determined by ASTM D HLE, Inc. Page 2

4 Pavement Sections: Based on the data obtained from the site and laboratory tests, it is our opinion that the native sod over sandy silt is not a suitable material for pavement subgrade. This soil provides little to no value as a subgrade material. HLE recommends the following sections; TABLE 2-RECOMMENDED PAVEMENT SECTION Layer Traffic Area (inches) Plant Mix Pavement 2.5 ¾ Crushed Aggregate Base 4 Uncrushed Aggregate Subbase 8 Geotextile Recommended Yes Total 14.5 Areas of the site which will underlie fill or topsoil underneath the pavement should be excavated to sufficient depths to expose the native poorly graded gravel with sand/silt. These areas should be scarified to a minimum depth of eight (8 ) and re-compacted to a minimum of 95% of the maximum density as of ASTM D-698, Standard Proctor, or 92 percent of ASTM D Introduction 2.1 Purpose and Detailed Scope-of-Service Our purpose in conducting a soils investigation is to accurately define and evaluate subsurface soil, bedrock, and ground water conditions in the areas of proposed construction, and to describe the engineering geology and geoseismic setting of the site. This information is used to provide appropriate foundation recommendations for design of the proposed structures and site elements. This investigation included subsurface exploration, soil sampling, laboratory testing, and engineering analysis and report preparation. The investigation also included review of local geological studies and records, and visual inspection of the site. The scope of our field exploration included logging and sampling of six test holes dug by Jefferson County using a backhoe excavator, laboratory testing as required for engineering analysis, and a report of the findings. The locations of the test holes are shown in Appendix A under Test Hole Location Map. 2.2 Project Description The proposed development is located at 210 Courthouse Way in Rigby, Idaho. The proposed development will be located on a acre parcel. The project consists of constructing an addition to the existing courthouse building, as well as two additional parking areas. The required allowable bearing capacity for the courthouse strip footings is 3,300 psf. HLE, Inc. Page 3

5 2.3 Limitations, Exceptions, and User Reliance We have conducted the soils study in accordance with the guidelines given in the 2012 International Building Code (IBC). The results of our investigation, along with pertinent recommendations for bearing capacity of the soils, are outlined in this report. The Associated Soil and Foundation Engineers (ASFE) organization has prepared information regarding geotechnical reports and a copy of that information has been attached for your review (Appendix C). The user of this report may rely on its findings as they assess the condition of subsurface soils on this site. We believe that the information gathered in this study is reliable but HLE, Inc. cannot guarantee that it is absolute or exactly precise; our conclusions are based on the parameters within which the investigation was conducted. No geotechnical investigation can wholly eliminate uncertainty regarding the soils in connection with the target property. The investigation is intended to reduce, but not eliminate, ambiguity regarding the potential to subsurface conditions in connection with a property. The Geotechnical Engineer should be contacted if the field conditions differ from those encountered during this investigation. 3.0 Site Description 3.1 Site Location and Current Property Use The proposed development is located at 210 Courthouse Way in Rigby, Idaho. The proposed structures are located on a acre parcel located in Section 18, T4N, R39E Lot 1, Rigby, Idaho. The proposed development is on a lot occupied by the Jefferson County Courthouse. The site is relatively flat. 3.2 Descriptions of Structures, Roads, Other On-Site Improvements The proposed location of the addition is in the back of the property on an undeveloped portion of the land. The new parking lots will extend into the existing retention pond locations, which will need to be enlarged and relocated. 3.3 Site Geology The Custom Soil Resource Report for Jefferson County, Idaho conducted by the United States Department of Agriculture (USDA) Natural Resources Conservation Service (NRCS) classifies three soil types, and a custom report for the site can be found in Appendix B. 3.4 Seismicity The project is located within seismic design category C as set forth in the 2012 IBC Section The following table defines the design criteria for the site. HLE, Inc. Page 4

6 Table 3: Seismic Design Category Summary SS 44.2 g S1 15.4% g Site Class C SMS 53.0% g SM1 25.4% g SDS 35.4% g SD1 16.9% g Seismic Design Category SS=mapped short period spectral response acceleration S1=mapped spectral response acceleration at 1-second period SMS=maximum earthquake spectral response acceleration for short periods SM1=maximum earthquake spectral response acceleration at 1-second period SDS=design short-period spectral response acceleration SD1=design spectral response acceleration at 1-second period From our investigation and the soils located on this property indicate they do not appear to be particularly susceptible to liquefaction, surface rupture, or other earthquake hazards. 4.0 Field Exploration 4.1 Exploration Summary HLE completed a field exploration to help determine the subsurface soil s engineering characteristics and location. Frank Sykes supervised the subsurface explorations at the project June 1, The characteristics of the subsurface materials were defined by digging 6 holes up to a depth of fifteen (15.0) feet. The test holes were dug by Jefferson County utilizing a backhoe excavator. 4.2 Exploration Procedures An experienced field technician supervised the exploration of the test pits. A continuous log of the subsurface conditions in the test pits were created (Appendix B), and a representative sample of each of the subsurface soils was collected, charted and classified in the field using ASTM D 2488 (Unified Soil Classification System) as a guide. Representative samples were taken to the laboratory for further testing. The test holes were backfilled after completion of inspection. 4.3 Lab Testing After the field investigation, a supplemental laboratory-testing program was conducted to determine additional pertinent physical and engineering properties of the subsurface soil. Laboratory tests were conducted according to current applicable American Society for Testing and Materials (ASTM) specifications. The following test methods and procedures were utilized: C HLE, Inc. Page 5

7 ASTM D Water Content ASTM D Classification of Soils for Engineering Purposes ASTM C136 - Sieve Analysis of Fine and Course Aggregates ASTM D422 - Standard Test Method for Particle-Size Analysis of Soils ASTM C117 - Materials Finer than 75-µm (No. 200) Sieve in Mineral Aggregate by Washing Soils logs generated by the field and lab investigation include soil strata, groundwater conditions, and general information regarding each test hole. A continuous log of the subsurface conditions in the test holes was created, and each of the subsurface soils were charted and classified. The boring log, gradation curves, and soil classifications can be seen in Appendix B. 4.4 Supplemental Information NA 4.5 Subsurface Soils Test pits were excavated up to a depth of twelve (15.0) feet. The following table depicts the soils encountered and their characteristics. TABLE 4-SOIL CHARACTERISTICS Soil Classification Internal Angle of Friction Tan ϕ Passive Pressure Coefficient Coefficient of Friction Sod over Sandy Silt (ML) Poorly Graded Gravel with Sand (GP) Silty Sand (SM) Poorly Graded Gravel with Sand and Silt (GP- GM) 4.6 Groundwater Table Groundwater was not encountered in any of the test holes but is estimated to be around deep. The test holes were dug during typical water season and it seems apparent that ground water should not be an issue for this project. 5.0 Foundation Recommendations 5.1 Bearing Capacity Based on a factor of safety of three, with respect to shear failure, the allowable load bearing capacity of the re-compacted native poorly graded gravel with sand (GP) is 3,300 psf. The allowable load bearing capacity of the re-compacted native poorly graded gravel with sand and silt (GP-GM) is 3,300 psf. Minimum footing depth is 36 for HLE, Inc. Page 6

8 frost protection. Should the Contractor not be able to obtain 92% compaction on the native soils, then install three (3 ) feet of compacted structural fill in accordance with the structural fill portion of this report. Use 3,300 psf for footing design. To accommodate sub grade inconsistencies, a minimum footing width of 36 inches should be specified for all foundations regardless of loading. Before placing any structures on the site, it is recommended that the structure is not placed on topsoil. If any portion of the structure is to be placed on topsoil, it is recommended to have the topsoil removed and any foundations be placed on a compacted structural fill. See Sections 5.2 through Structural Fill and Foundation Considerations Placement of any fill material beneath the footing elevation, if necessary, should be accomplished with a GW, or GP Class sandy gravel material, placed in lifts not exceeding 8 inches and compacted to a minimum of 95 percent of optimum dry density as determined by ASTM D1557. A qualified inspector approved by the building official should verify the compaction. The fill should extend a minimum width of six inches beyond the footing at its base, and should widen at an angle of 45 from the footing base to the bottom of the footing trench. By limiting the total pressure on spread footings to the above-recommended capacities, differential settlement of footings should be within a half inch (1/2 ) and total settlement should not exceed one inch (1 ). Under no circumstances should the footings be installed upon loose or saturated soil, sod, rubbish, construction debris, frozen soil, nonengineered fill, or other deleterious materials, or within ponded water. If unsuitable soils such as rocks larger than 12 inches in diameter, concrete or pipe are encountered in any footing trench, they must be completely removed and replaced with compacted structural fill. If granular soils become loose or disturbed, they must be properly recompacted before the footings are placed. It is not anticipated that the footing trenches will extend more than four feet below the foundation footing elevation. It is recommended that site preparation be completed in accordance with Section 6.0 of this report. Backfill behind any truck dock walls, foundation walls and/or grade beams should be done with a two-inch minus free draining material with less than 15% passing the #200 sieve. We recommend that a geotechnical engineer or testing technician from HLE be contacted to observe the excavation and foundation preparation phases of the project to determine that actual conditions are compatible with those considered for this report and recommendations. Placement of all fill and foundation soil should be observed and tested to confirm that the proper density and depth has been achieved in accordance with this report. HLE, Inc. Page 7

9 5.3 Structural Fill and Foundation Considerations HLE recommends the areas of the site which will underlie fill or topsoil underneath the pavement should be excavated to sufficient depths to expose the native poorly graded gravel with sand/silt. These areas should be scarified to a minimum depth of eight (8 ) and re-compacted to a minimum of 95% of the maximum density as of ASTM D-698, Standard Proctor. The pavement ballast section should then be placed on the compacted subgrade. 6.0 Site Preparation, Compacted Fill Requirements and Pavement Design 6.1 Site Preparation Foundation, Floor Slab, and Pavement Areas Prior to placing any structures on the proposed site, any remaining demolition debris and organic materials should be stripped and removed from the proposed structure footprint, including the sod with sandy silt and the silty sand. Stripping operations should extend approximately 10 feet beyond the building perimeter and to a depth sufficient to remove all organics and other deleterious materials. The entire foundation footprint of any structure should be compacted to an in-place unit weight equal to at least 92.0 percent on native material and 95.0 percent on structural fill material of optimum dry density as determined by ASTM D1557 and tested to verify that the specified density has been obtained prior to construction. Sufficient quality assurance testing should be performed to ensure that compaction specifications are complied with. Under no circumstances should the footings be installed upon loose or saturated soil, sod, rubbish, construction debris, frozen soil, non-engineered fill, or other deleterious materials, or within ponded water. If unsuitable soils are encountered, they must be totally removed and replaced with compacted structural fill. If granular soils become loose or disturbed, they must be properly re-compacted before the footings are placed. Buried irrigation main lines and valves should be kept at least six feet from bearing walls. Placement of any fill material beneath the footing elevation, if necessary, should be accomplished with a GW or GP Class sandy gravel material, placed in lifts not exceeding 8 inches and compacted to a minimum of 95 percent of optimum dry density as determined by ASTM D1557. A qualified inspector approved by the building official should verify the compaction. The fill should extend a minimum width of six inches beyond the footing at its base, and should widen at an angle of 45 from the footing base to the bottom of the footing trench Under-slab vapor barriers should be required under slabs below air-conditioned space HLE, Inc. Page 8

10 and slabs that are covered with flooring systems. Under slab vapor barriers should have a perm rating at least equal to the flooring system inclusive of its adhesive. Cushions and blotters of sand, gravel or fill should not be installed on top of under slab vapor barriers. The vapor barrier should have all laps, seams, penetrations, and terminations sealed and should either carry across footings, grade beams and foundations or be turned up to the top of the slab at these elements and sealed. Placement should conform to recommendations of ACI 302.1R-96 as revised. 6.2 Wet Weather Construction Wet weather construction conditions may occur from November to April. The natural poorly graded gravel with sand with silt is susceptible to changes in moisture content. During construction, the superficial soils may begin to pump and/or rut. If excessive precipitation creates a situation where the soils have excessive moisture beyond the optimum, construction technique will need to be modified. The following methods are for wet weather construction: Restrict traffic over cleared and grubbed areas to tracked vehicles only. Restrict all rubber-tired vehicles from the proposed foundation and pavement areas. If the moisture content of soils is determined to be too high, the exposed sub grade should be scarified and/or disked to aerate and accelerate the drying of the soils. This process should be repeated as necessary to reduce the moisture content to optimum levels. Once the material is dry it should be proof-rolled before placing structural fill. If these methods do not work it may be necessary to over-excavate the problematic soils and import a non-moisture sensitive sand and gravel. HLE should be contacted to evaluate site conditions and provide recommendations to the owner. 6.3 Pavement Design Roadways and parking areas may be construction on properly prepared sandy gravel material found on the site. Pavement design is based on the AASHTO Guide for Design of Pavement Structures We recommend stripping any remaining vegetation within areas that are to be paved, and excavation of all native sandy silts. Any areas requiring more than 14.5 of excavation may be filled with compacted engineered fill in lifts not to exceed 12. All subgrade materials should be compacted to a density of 95 percent of ASTM D698 or 92 percent of ASTM D1557. The recommended ballast section described below should be placed on top of this compacted soil. HLE typically recommends the use of a pit-run base in all ballast sections and recommends the following pavement section for the conditions found at this site: HLE, Inc. Page 9

11 TABLE 5-RECOMMENDED PAVEMENT SECTION Layer Traffic Area (inches) Plant Mix Pavement 2.5 ¾ Crushed Aggregate Base 4 Uncrushed Aggregate Subbase 8 Geotextile Recommended Yes Total 14.5 These pavement recommendations meet the minimum design requirements for the AASHTO pavement design standards. HLE should be notified of any variations to the recommended pavement sizes. Pavement Materials should consist of materials that conform to the following sections of the ITD Standard Specifications, latest edition. Portland cement shall conform to section 701. Asphalt shall conform to section 702 and shall meet the requirements of Performance Grade Aggregates shall conform to section 703 of the standard specifications. All base and subbase materials used under the pavement should be compacted to at least 95 percent of optimum dry density as determined by ASTM D698 or 92 percent of ASTM D1557 at a rate of 1 test per 10,000 sq. ft. each lift. 7.0 Conclusions The conclusions and recommendations presented in this report are based upon the field and laboratory tests, which in our opinion define the characteristics of the subsurface material throughout the site in a satisfactory manner. Please refer to the ASFE information provided with this report concerning the use of your geotechnical evaluation. If during construction, conditions are encountered which appear to differ from those presented in this report, or if the site design layout is changed or significantly adjusted, it is requested that we be advised in order that appropriate action, including revisions to this report, may be taken. We appreciate the opportunity to provide you with geotechnical services on this project. Contact us about performing testing and inspections services once you begin construction. If you have any questions regarding this report or any of our engineering, testing, or design services please feel free to get in touch with our office, or see our web site: Our experienced and knowledgeable staff will be happy to answer any questions that may arise. As a valued client please let us know how we can better serve your needs. We look forward to working with you again on any of your future Surveying and Civil, Geotechnical, or Environmental Engineering projects. HLE, Inc. Page 10

12 APPENDIX A Vicinity Map, Test Hole Map, Photos

13 Jefferson County Courthouse June 13, 2017 Trailhead Emergency Closure Jeep Jeep Seasonal Other Road Wilderness 1:72, mi km Selected ATV Ranger_Districts Highway Legal Highway Legal Seasonal Automobile Automobile Seasonal ATV Seasonal Motorcycle Motorcycle Seasonal Non-Motorized BLM Counties Weather Fire Emergency Closures Idaho Department of Parks and Recreation IDFG IFWIS Copyright: 2013 National Geographic Society, i-cubed Idaho Department of Parks & Recreation IDFG IFWIS Idaho Department of Parks and Recreation Copyright: 2013 National Geographic Society, i-cubed

14 Jefferson County Courthouse Jefferson County Courthouse June 13, 2017 Trailhead Emergency Closure Jeep Jeep Seasonal Other Road Wilderness 1:36, mi km Selected ATV Ranger_Districts Highway Legal Highway Legal Seasonal Automobile Automobile Seasonal ATV Seasonal Motorcycle Motorcycle Seasonal Non-Motorized BLM Counties Weather Fire Emergency Closures Idaho Department of Parks and Recreation IDFG IFWIS Copyright: 2013 National Geographic Society, i-cubed Idaho Department of Parks & Recreation IDFG IFWIS Idaho Department of Parks and Recreation Copyright: 2013 National Geographic Society, i-cubed

15 Test Hole Location Map TH-01 TH-03 TH-04 TH-05 TH-02 TH-06

16 APPENDIX B Soil Logs, Log Data and USDA Soil Survey

17 PROJECT NAME: PROJECT NUMBER: LOCATION: TYPE OF DRILL RIG: HOLE SIZE: DEPTH TO WATER: LOGGED BY: DEPTH (FEET) ELEVATION SAMPLES BLOW COUNTS Jefferson County Courts House Addition Rigby, Idaho Backhoe 3 X 10 Not Encountered Frank Sykes DESCRIPTION GRAPHIC LOG SHEET BOREHOLE NUMBER: DRILLER: HAMMER: SURFACE ELEVATION: DATE: 1 OF 1 Jefferson County DROP: /1/17 TO 6/1/17 TH-01 MOISTURE (%) DRY DENSITY (PCF) DEGREE OF SATURATION (%) PLASTIC LIMIT (%) LIQUID LIMIT (%) Sod over Sandy Silt ML Poorly Graded Gravel with Sand GP Bottom of Test Hole LAGNGN GPJ LAGNGN02.GDT 6/8/ HLE Engineering 985 No. capital ave. Idaho Falls, Idaho Fax: FIGURE: 3

18 PROJECT NAME: PROJECT NUMBER: LOCATION: TYPE OF DRILL RIG: HOLE SIZE: DEPTH TO WATER: LOGGED BY: DEPTH (FEET) ELEVATION SAMPLES BLOW COUNTS Jefferson County Courts House Addition Rigby, Idaho Backhoe 3 X 10 Not Encountered Frank Sykes DESCRIPTION GRAPHIC LOG SHEET BOREHOLE NUMBER: DRILLER: HAMMER: SURFACE ELEVATION: DATE: 1 OF 1 Jefferson County DROP: /1/17 TO 6/1/17 TH-02 MOISTURE (%) DRY DENSITY (PCF) DEGREE OF SATURATION (%) PLASTIC LIMIT (%) LIQUID LIMIT (%) Sod over Sandy Silt ML Poorly Graded Gravel with Sand GP LAGNGN GPJ LAGNGN02.GDT 6/8/ HLE Engineering 985 No. capital ave. Idaho Falls, Idaho Fax: Bottom of Test Hole FIGURE: 4

19 PROJECT NAME: PROJECT NUMBER: LOCATION: TYPE OF DRILL RIG: HOLE SIZE: DEPTH TO WATER: LOGGED BY: DEPTH (FEET) ELEVATION SAMPLES BLOW COUNTS Jefferson County Courts House Addition Rigby, Idaho Backhoe 3 X 10 Not Encountered Frank Sykes DESCRIPTION GRAPHIC LOG SHEET BOREHOLE NUMBER: DRILLER: SURFACE ELEVATION: DATE: 1 OF 1 Jefferson County HAMMER: DROP: /1/17 TO 6/1/17 TH-03 MOISTURE (%) DRY DENSITY (PCF) DEGREE OF SATURATION (%) PLASTIC LIMIT (%) LIQUID LIMIT (%) Sod over Sandy Silt ML Silty Sand SM Poorly Graded Gravel with Sand and Silt GP-GM Bottom of Test Hole LAGNGN GPJ LAGNGN02.GDT 6/8/ HLE Engineering 985 No. capital ave. Idaho Falls, Idaho Fax: FIGURE: 5

20 PROJECT NAME: PROJECT NUMBER: LOCATION: TYPE OF DRILL RIG: HOLE SIZE: DEPTH TO WATER: LOGGED BY: DEPTH (FEET) ELEVATION SAMPLES BLOW COUNTS Jefferson County Courts House Addition Rigby, Idaho Backhoe 3 X 10 Not Encountered Frank Sykes DESCRIPTION GRAPHIC LOG SHEET BOREHOLE NUMBER: DRILLER: HAMMER: SURFACE ELEVATION: DATE: 1 OF 1 Jefferson County DROP: /1/17 TO 6/1/17 TH-04 MOISTURE (%) DRY DENSITY (PCF) DEGREE OF SATURATION (%) PLASTIC LIMIT (%) LIQUID LIMIT (%) Sod over Sandy Silt ML Poorly Graded Gravel with Sand GP LAGNGN GPJ LAGNGN02.GDT 6/8/ HLE Engineering 985 No. capital ave. Idaho Falls, Idaho Fax: Bottom of Test Hole FIGURE: 6

21 PROJECT NAME: PROJECT NUMBER: LOCATION: TYPE OF DRILL RIG: HOLE SIZE: DEPTH TO WATER: LOGGED BY: DEPTH (FEET) ELEVATION SAMPLES BLOW COUNTS Jefferson County Courts House Addition Rigby, Idaho Backhoe 3 X 10 Not Encountered Frank Sykes DESCRIPTION GRAPHIC LOG SHEET BOREHOLE NUMBER: DRILLER: HAMMER: SURFACE ELEVATION: DATE: 1 OF 1 Jefferson County DROP: /1/17 TO 6/1/17 TH-05 MOISTURE (%) DRY DENSITY (PCF) DEGREE OF SATURATION (%) PLASTIC LIMIT (%) LIQUID LIMIT (%) Sod over Sandy Silt ML Poorly Graded Gravel with Sand GP Bottom of Test Hole LAGNGN GPJ LAGNGN02.GDT 6/8/ HLE Engineering 985 No. capital ave. Idaho Falls, Idaho Fax: FIGURE: 7

22 PROJECT NAME: PROJECT NUMBER: LOCATION: TYPE OF DRILL RIG: HOLE SIZE: DEPTH TO WATER: LOGGED BY: DEPTH (FEET) ELEVATION SAMPLES BLOW COUNTS Jefferson County Courts House Addition Rigby, Idaho Backhoe 3 X 10 Not Encountered Frank Sykes DESCRIPTION GRAPHIC LOG SHEET BOREHOLE NUMBER: DRILLER: HAMMER: SURFACE ELEVATION: DATE: 1 OF 1 Jefferson County DROP: /1/17 TO 6/1/17 TH-06 MOISTURE (%) DRY DENSITY (PCF) DEGREE OF SATURATION (%) PLASTIC LIMIT (%) LIQUID LIMIT (%) Sod over Sandy Silt ML Poorly Graded Gravel with Sand GP LAGNGN GPJ LAGNGN02.GDT 6/8/ HLE Engineering 985 No. capital ave. Idaho Falls, Idaho Fax: Bottom of Test Hole FIGURE: 8

23 100 U.S. SIEVE OPENING IN INCHES U.S. SIEVE NUMBERS /41/23/ HYDROMETER P E R C E N T F I N E R B Y W E I G H T COBBLES TH-01 TH-02 TH-03 TH-03 TH-06 PROJECT 100 Specimen Identification TH-01 TH-02 TH-03 TH-03 TH Specimen Identification GRAVEL coarse fine GRAIN SIZE IN MILLIMETERS D GRADATION CURVES MC% POORLY GRADED GRAVEL w/ SILT & SAND GP-GM < D coarse Classification D60 SAND medium Jefferson County Courts House Addition - Rigby, Idaho D10 fine POORLY GRADED GRAVEL with SAND GP SANDY SILT ML SILTY SAND SM POORLY GRADED GRAVEL with SAND GP < < < < LL NP NP NP NP NP SILT OR CLAY HLE Engineering Idaho Falls, Idaho %Gravel JOB NO. DATE PL NP NP NP NP NP %Sand PI NP NP NP NP NP Figure No. 2 %Silt Cc /8/17 Cu %Clay

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25 United States Department of Agriculture Natural Resources Conservation Service A product of the National Cooperative Soil Survey, a joint effort of the United States Department of Agriculture and other Federal agencies, State agencies including the Agricultural Experiment Stations, and local participants Custom Soil Resource Report for Jefferson County, Idaho June 12, 2017

26 Preface Soil surveys contain information that affects land use planning in survey areas. They highlight soil limitations that affect various land uses and provide information about the properties of the soils in the survey areas. Soil surveys are designed for many different users, including farmers, ranchers, foresters, agronomists, urban planners, community officials, engineers, developers, builders, and home buyers. Also, conservationists, teachers, students, and specialists in recreation, waste disposal, and pollution control can use the surveys to help them understand, protect, or enhance the environment. Various land use regulations of Federal, State, and local governments may impose special restrictions on land use or land treatment. Soil surveys identify soil properties that are used in making various land use or land treatment decisions. The information is intended to help the land users identify and reduce the effects of soil limitations on various land uses. The landowner or user is responsible for identifying and complying with existing laws and regulations. Although soil survey information can be used for general farm, local, and wider area planning, onsite investigation is needed to supplement this information in some cases. Examples include soil quality assessments ( portal/nrcs/main/soils/health/) and certain conservation and engineering applications. For more detailed information, contact your local USDA Service Center ( or your NRCS State Soil Scientist ( cid=nrcs142p2_053951). Great differences in soil properties can occur within short distances. Some soils are seasonally wet or subject to flooding. Some are too unstable to be used as a foundation for buildings or roads. Clayey or wet soils are poorly suited to use as septic tank absorption fields. A high water table makes a soil poorly suited to basements or underground installations. The National Cooperative Soil Survey is a joint effort of the United States Department of Agriculture and other Federal agencies, State agencies including the Agricultural Experiment Stations, and local agencies. The Natural Resources Conservation Service (NRCS) has leadership for the Federal part of the National Cooperative Soil Survey. Information about soils is updated periodically. Updated information is available through the NRCS Web Soil Survey, the site for official soil survey information. The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and activities on the basis of race, color, national origin, age, disability, and where applicable, sex, marital status, familial status, parental status, religion, sexual orientation, genetic information, political beliefs, reprisal, or because all or a part of an individual's income is derived from any public assistance program. (Not all prohibited bases apply to all programs.) Persons with disabilities who require 2

27 alternative means for communication of program information (Braille, large print, audiotape, etc.) should contact USDA's TARGET Center at (202) (voice and TDD). To file a complaint of discrimination, write to USDA, Director, Office of Civil Rights, 1400 Independence Avenue, S.W., Washington, D.C or call (800) (voice) or (202) (TDD). USDA is an equal opportunity provider and employer. 3

28 Contents Preface... 2 How Soil Surveys Are Made...5 Soil Map... 8 Soil Map...9 Legend...10 Map Unit Legend Map Unit Descriptions...11 Jefferson County, Idaho Hayeston loam Urban land Xeric Torrifluvents References

29 How Soil Surveys Are Made Soil surveys are made to provide information about the soils and miscellaneous areas in a specific area. They include a description of the soils and miscellaneous areas and their location on the landscape and tables that show soil properties and limitations affecting various uses. Soil scientists observed the steepness, length, and shape of the slopes; the general pattern of drainage; the kinds of crops and native plants; and the kinds of bedrock. They observed and described many soil profiles. A soil profile is the sequence of natural layers, or horizons, in a soil. The profile extends from the surface down into the unconsolidated material in which the soil formed or from the surface down to bedrock. The unconsolidated material is devoid of roots and other living organisms and has not been changed by other biological activity. Currently, soils are mapped according to the boundaries of major land resource areas (MLRAs). MLRAs are geographically associated land resource units that share common characteristics related to physiography, geology, climate, water resources, soils, biological resources, and land uses (USDA, 2006). Soil survey areas typically consist of parts of one or more MLRA. The soils and miscellaneous areas in a survey area occur in an orderly pattern that is related to the geology, landforms, relief, climate, and natural vegetation of the area. Each kind of soil and miscellaneous area is associated with a particular kind of landform or with a segment of the landform. By observing the soils and miscellaneous areas in the survey area and relating their position to specific segments of the landform, a soil scientist develops a concept, or model, of how they were formed. Thus, during mapping, this model enables the soil scientist to predict with a considerable degree of accuracy the kind of soil or miscellaneous area at a specific location on the landscape. Commonly, individual soils on the landscape merge into one another as their characteristics gradually change. To construct an accurate soil map, however, soil scientists must determine the boundaries between the soils. They can observe only a limited number of soil profiles. Nevertheless, these observations, supplemented by an understanding of the soil-vegetation-landscape relationship, are sufficient to verify predictions of the kinds of soil in an area and to determine the boundaries. Soil scientists recorded the characteristics of the soil profiles that they studied. They noted soil color, texture, size and shape of soil aggregates, kind and amount of rock fragments, distribution of plant roots, reaction, and other features that enable them to identify soils. After describing the soils in the survey area and determining their properties, the soil scientists assigned the soils to taxonomic classes (units). Taxonomic classes are concepts. Each taxonomic class has a set of soil characteristics with precisely defined limits. The classes are used as a basis for comparison to classify soils systematically. Soil taxonomy, the system of taxonomic classification used in the United States, is based mainly on the kind and character of soil properties and the arrangement of horizons within the profile. After the soil 5

30 Custom Soil Resource Report scientists classified and named the soils in the survey area, they compared the individual soils with similar soils in the same taxonomic class in other areas so that they could confirm data and assemble additional data based on experience and research. The objective of soil mapping is not to delineate pure map unit components; the objective is to separate the landscape into landforms or landform segments that have similar use and management requirements. Each map unit is defined by a unique combination of soil components and/or miscellaneous areas in predictable proportions. Some components may be highly contrasting to the other components of the map unit. The presence of minor components in a map unit in no way diminishes the usefulness or accuracy of the data. The delineation of such landforms and landform segments on the map provides sufficient information for the development of resource plans. If intensive use of small areas is planned, onsite investigation is needed to define and locate the soils and miscellaneous areas. Soil scientists make many field observations in the process of producing a soil map. The frequency of observation is dependent upon several factors, including scale of mapping, intensity of mapping, design of map units, complexity of the landscape, and experience of the soil scientist. Observations are made to test and refine the soil-landscape model and predictions and to verify the classification of the soils at specific locations. Once the soil-landscape model is refined, a significantly smaller number of measurements of individual soil properties are made and recorded. These measurements may include field measurements, such as those for color, depth to bedrock, and texture, and laboratory measurements, such as those for content of sand, silt, clay, salt, and other components. Properties of each soil typically vary from one point to another across the landscape. Observations for map unit components are aggregated to develop ranges of characteristics for the components. The aggregated values are presented. Direct measurements do not exist for every property presented for every map unit component. Values for some properties are estimated from combinations of other properties. While a soil survey is in progress, samples of some of the soils in the area generally are collected for laboratory analyses and for engineering tests. Soil scientists interpret the data from these analyses and tests as well as the field-observed characteristics and the soil properties to determine the expected behavior of the soils under different uses. Interpretations for all of the soils are field tested through observation of the soils in different uses and under different levels of management. Some interpretations are modified to fit local conditions, and some new interpretations are developed to meet local needs. Data are assembled from other sources, such as research information, production records, and field experience of specialists. For example, data on crop yields under defined levels of management are assembled from farm records and from field or plot experiments on the same kinds of soil. Predictions about soil behavior are based not only on soil properties but also on such variables as climate and biological activity. Soil conditions are predictable over long periods of time, but they are not predictable from year to year. For example, soil scientists can predict with a fairly high degree of accuracy that a given soil will have a high water table within certain depths in most years, but they cannot predict that a high water table will always be at a specific level in the soil on a specific date. After soil scientists located and identified the significant natural bodies of soil in the survey area, they drew the boundaries of these bodies on aerial photographs and 6

31 Custom Soil Resource Report identified each as a specific map unit. Aerial photographs show trees, buildings, fields, roads, and rivers, all of which help in locating boundaries accurately. 7

32 Soil Map The soil map section includes the soil map for the defined area of interest, a list of soil map units on the map and extent of each map unit, and cartographic symbols displayed on the map. Also presented are various metadata about data used to produce the map, and a description of each soil map unit. 8

33 111 54' 43'' W Custom Soil Resource Report Soil Map ' 30'' W ' 45'' N Soil Map may not be valid at this scale ' 45'' N 43 40' 39'' N ' 39'' N ' 43'' W N Map Scale: 1:1,260 if printed on A landscape (11" x 8.5") sheet. Meters Feet Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 12N WGS ' 30'' W

34 Custom Soil Resource Report MAP LEGEND MAP INFORMATION Area of Interest (AOI) Area of Interest (AOI) Soils Soil Map Unit Polygons Soil Map Unit Lines Soil Map Unit Points Special Point Features Blowout Borrow Pit Clay Spot Closed Depression Gravel Pit Gravelly Spot Landfill Lava Flow Marsh or swamp Mine or Quarry Miscellaneous Water Perennial Water Rock Outcrop Saline Spot Sandy Spot Severely Eroded Spot Sinkhole Slide or Slip Sodic Spot Spoil Area Stony Spot Very Stony Spot Wet Spot Other Special Line Features Water Features Streams and Canals Transportation Rails Interstate Highways US Routes Major Roads Local Roads Background Aerial Photography The soil surveys that comprise your AOI were mapped at 1:24,000. Warning: Soil Map may not be valid at this scale. Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale. Please rely on the bar scale on each map sheet for map measurements. Source of Map: Natural Resources Conservation Service Web Soil Survey URL: Coordinate System: Web Mercator (EPSG:3857) Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Albers equal-area conic projection, should be used if more accurate calculations of distance or area are required. This product is generated from the USDA-NRCS certified data as of the version date(s) listed below. Soil Survey Area: Jefferson County, Idaho Survey Area Data: Version 13, Sep 25, 2015 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Jul 20, 2011 Jul 21, 2011 The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting of map unit boundaries may be evident. 10

35 Custom Soil Resource Report Map Unit Legend Jefferson County, Idaho (ID765) Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI 42 Hayeston loam % 118 Urban land % 124 Xeric Torrifluvents % Totals for Area of Interest % Map Unit Descriptions The map units delineated on the detailed soil maps in a soil survey represent the soils or miscellaneous areas in the survey area. The map unit descriptions, along with the maps, can be used to determine the composition and properties of a unit. A map unit delineation on a soil map represents an area dominated by one or more major kinds of soil or miscellaneous areas. A map unit is identified and named according to the taxonomic classification of the dominant soils. Within a taxonomic class there are precisely defined limits for the properties of the soils. On the landscape, however, the soils are natural phenomena, and they have the characteristic variability of all natural phenomena. Thus, the range of some observed properties may extend beyond the limits defined for a taxonomic class. Areas of soils of a single taxonomic class rarely, if ever, can be mapped without including areas of other taxonomic classes. Consequently, every map unit is made up of the soils or miscellaneous areas for which it is named and some minor components that belong to taxonomic classes other than those of the major soils. Most minor soils have properties similar to those of the dominant soil or soils in the map unit, and thus they do not affect use and management. These are called noncontrasting, or similar, components. They may or may not be mentioned in a particular map unit description. Other minor components, however, have properties and behavioral characteristics divergent enough to affect use or to require different management. These are called contrasting, or dissimilar, components. They generally are in small areas and could not be mapped separately because of the scale used. Some small areas of strongly contrasting soils or miscellaneous areas are identified by a special symbol on the maps. If included in the database for a given area, the contrasting minor components are identified in the map unit descriptions along with some characteristics of each. A few areas of minor components may not have been observed, and consequently they are not mentioned in the descriptions, especially where the pattern was so complex that it was impractical to make enough observations to identify all the soils and miscellaneous areas on the landscape. The presence of minor components in a map unit in no way diminishes the usefulness or accuracy of the data. The objective of mapping is not to delineate pure taxonomic classes but rather to separate the landscape into landforms or landform segments that have similar use and management requirements. The delineation of such segments on the map provides sufficient information for the 11

36 Custom Soil Resource Report development of resource plans. If intensive use of small areas is planned, however, onsite investigation is needed to define and locate the soils and miscellaneous areas. An identifying symbol precedes the map unit name in the map unit descriptions. Each description includes general facts about the unit and gives important soil properties and qualities. Soils that have profiles that are almost alike make up a soil series. Except for differences in texture of the surface layer, all the soils of a series have major horizons that are similar in composition, thickness, and arrangement. Soils of one series can differ in texture of the surface layer, slope, stoniness, salinity, degree of erosion, and other characteristics that affect their use. On the basis of such differences, a soil series is divided into soil phases. Most of the areas shown on the detailed soil maps are phases of soil series. The name of a soil phase commonly indicates a feature that affects use or management. For example, Alpha silt loam, 0 to 2 percent slopes, is a phase of the Alpha series. Some map units are made up of two or more major soils or miscellaneous areas. These map units are complexes, associations, or undifferentiated groups. A complex consists of two or more soils or miscellaneous areas in such an intricate pattern or in such small areas that they cannot be shown separately on the maps. The pattern and proportion of the soils or miscellaneous areas are somewhat similar in all areas. Alpha-Beta complex, 0 to 6 percent slopes, is an example. An association is made up of two or more geographically associated soils or miscellaneous areas that are shown as one unit on the maps. Because of present or anticipated uses of the map units in the survey area, it was not considered practical or necessary to map the soils or miscellaneous areas separately. The pattern and relative proportion of the soils or miscellaneous areas are somewhat similar. Alpha-Beta association, 0 to 2 percent slopes, is an example. An undifferentiated group is made up of two or more soils or miscellaneous areas that could be mapped individually but are mapped as one unit because similar interpretations can be made for use and management. The pattern and proportion of the soils or miscellaneous areas in a mapped area are not uniform. An area can be made up of only one of the major soils or miscellaneous areas, or it can be made up of all of them. Alpha and Beta soils, 0 to 2 percent slopes, is an example. Some surveys include miscellaneous areas. Such areas have little or no soil material and support little or no vegetation. Rock outcrop is an example. 12