March 31, 201 11 Northstar Avenue 83301 Attn: Mr. Tracy Ahrens, P. E. E: taa@jub.com Re: Geotechnical Data Report Preliminary Phase 1 Field Exploration Revision No. 1 Proposed Rapid Infiltration Basin Terracon Dear Mr. Ahrens: This letter summarizes the results of Terracon s preliminary Phase 1 field services performed for a proposed rapid infiltration basin in. Our services were performed in general accordance with our Proposal for Geotechnical Engineering Services dated February 20, 201 (Terracon Proposal No. P6210026). (J-U-B) authorized the preliminary Phase 1 Services that are described in the referenced proposal. The Phase 2 Services described in that proposal have not been authorized. Project Understanding A rapid infiltration basin is proposed for construction by the City of. The proposed basin location is within an approximately 0-acre site located east of the intersection of Champlin Way (N. 3300 East Road) and Eldridge Avenue near. The general site location can be observed on the Exploration Plan, which is presented as Exhibit A-1 in Appendix A of this letter. The proposed project site currently consists of farm fields. We understand the proposed basin will likely be surrounded by relatively small berms, and any excavation within the basin area will likely be 4 feet or less. The purpose of our services was to perform a preliminary field exploration and laboratory testing of select samples of the soils encountered to aid in the conceptual development of the project. In accordance with our proposal, our services did not include geotechnical engineering analysis or recommendations. Field Exploration Ten test pits were excavated to depths ranging from about 8 to 12 feet below the existing ground surface to explore subsurface conditions in the proposed rapid infiltration basin area. Several of the test pits were terminated due to refusal on strongly cemented soils or basalt rock. The approximate test pit locations are presented on the Exploration Plan in Exhibit A-1 of Appendix A. Terracon Consultants, Inc. 11849 West Executive Drive, Suite G 83713 P [208] 323 920 F [208] 323 992 terracon.com
Geotechnical Data Report Preliminary Field Exploration Proposed Rapid Infiltration Basin March 31, 201 Terracon Project No. 621010 The test pits were excavated by a City of Kimberly employee using a rubber tire backhoe. A Terracon field engineer recorded logs of the test pits during excavation and obtained disturbed soil samples from selected soil layers within each test pit. Copies of the test pit logs are attached in Appendix A. The test pit locations were selected by City of Kimberly employees. Terracon recorded the test pit locations in the field using a recreational grade GPS unit having accuracy typically within approximately 20 feet and by visually sighting from existing site features. The locations are presented on the test pit logs and should be considered accurate only to the degree implied by the means and methods used to define them. Laboratory Testing Samples obtained during the field exploration were taken to the laboratory and visually classified in general accordance with the Unified Soil Classification System, described in Appendix B. Representative samples were selected for limited testing to determine physical and engineering properties of the subsurface materials. Following are the laboratory tests conducted and a brief description of the purpose of each test: Test Conducted Natural moisture content Percent passing the No. 200 sieve Atterberg limits To Determine: Moisture content of the sample. Percent of clay/silt sized particles in the sample. Plasticity of the sample. The tests were performed in general accordance with the respective ASTM standards. These standards are a reference to the general methodology used. In some cases, variations to methods are applied as a result of local practice or professional judgment. Test results are summarized on the test pit logs in Appendix A. Soil Conditions Soil conditions encountered at the test pit locations are indicated on the attached test pit logs. Stratification boundaries on the logs represent the approximate locations of changes in soil types; in-situ, the transition between materials may be gradual. Description Approximate Depth 1 to Bottom of Stratum Material Encountered Stratum 1 Stratum 2 1½ feet (where encountered) 9½ feet in test pit TP-3. Within the remaining test pits this stratum extended to the maximum depths explored, which ranged from about 8 to 12 feet. Lean clay. This stratum was only encountered in test pit TP-1. Silt to sandy silt. Portions of this stratum were variably cemented. See the paragraph below. Responsive Resourceful Reliable 2
Geotechnical Data Report Preliminary Field Exploration Proposed Rapid Infiltration Basin March 31, 201 Terracon Project No. 621010 Description Approximate Depth 1 to Bottom of Stratum Material Encountered Stratum 4 9½ feet (where encountered) 1. Depth below existing ground surface, as encountered in the test pits. Basalt rock. Rock was identified in test pit TP-3 at a depth of about 9½ feet. Test Pit TP-9 encountered refusal on what may have been basalt rock at a depth of about 8 feet. The silt layer described as Stratum 2 in the table above contained variably cemented layers. Within five of the 10 test pits, a weakly cemented layer about 1 to 1½ foot thick was encountered at a depth of about 1½ to 2 feet below the ground surface. A layer of weakly to strongly cemented silt to sandy silt was encountered in each test pit at a depth of about 7 to 11 feet below the ground surface. These materials were generally difficult to excavate. In addition to these two specific cemented layers, variable zones with a slight cemented structure were encountered in some of the test pits. Based on our past experience, we anticipate the infiltration rate into the weakly to strongly cemented layers could be very slow. Infiltration testing was not included in our scope of services. Groundwater The test pits were monitored during excavation for the presence of groundwater. Groundwater was not encountered during the exploration. Fluctuations in groundwater depth may occur due to seasonal variations in the amount of irrigation, rainfall, runoff, amount of water in nearby ditches and canals, and other factors not evident at the time the test pits were performed. Evaluation of these factors is beyond the scope of this exploration. Closure If this site is selected for development of the project, additional geotechnical services should be performed to obtain additional geotechnical data, as needed and provide geotechnical recommendations for design and construction. This report does not reflect variations that may occur adjacent to the test pits, across the site, or due to the modifying effects of construction or weather. The nature and extent of such variations may not become evident until during or after construction. The scope of services for this project does not include either specifically or by implication any environmental or biological (e.g., mold, fungi, and bacteria) assessment of the site or identification or prevention of pollutants, hazardous materials or conditions. If the owner is concerned about the potential for such contamination or pollution, other studies should be undertaken. This report has been prepared for the exclusive use of our client for specific application to the project discussed and has been prepared in accordance with generally accepted geotechnical engineering practices. No warranties, either expressed or implied, are intended or made. Site safety, excavation support, and dewatering requirements are the responsibility of others. Responsive Resourceful Reliable 3
APPENDIX A
AERIAL PHOTOGRAPHY PROVIDED BY MICROSOFT BING MAPS DIAGRAM IS FOR GENERAL ONLY, AND IS NOT INTENDED FOR CONSTRUCTION PURPOSES Project Manager: RJO Drawn by: DAF Checked by: RJO Approved by: CAW Project No. 621010 Scale: AS SHOWN File Name: EXPLORE Date: 3/17/1 11849 W. Executive Dr. Suite G Boise, ID 83713 EXPLORATION PLAN Proposed Rapid Infiltration Basin Exhibit A-1
TEST PIT LOG NO. TP-1 Latitude: 42.402107 Longitude: -114.3991699 LEAN CLAY (CL), brown (Ft.) 1. SILT (ML), light brown to brown slight cemented structure from 2 to 4 ft 20 NP 92 THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL 621010.GPJ TERRACON2012.GDT 3/23/1 11.3 variable zones of weak cementation from 7 to 8. ft variable zones of weak to moderate cementation below 8. ft Test Pit Terminated at 11.3 Feet 10 Test Pit Completed: 3/16/201 Exhibit: A-2
TEST PIT LOG NO. TP-2 Latitude: 42.399742 Longitude: -114.3972473 SILT (ML), light brown to brown (Ft.) variable zones with a slight cemented structure from 2. to 9 ft THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL 621010.GPJ TERRACON2012.GDT 3/23/1 weak to moderate cementation below 9 ft 11.8 Test Pit Terminated at 11.8 Feet 10 Test Pit Completed: 3/16/201 Exhibit: A-3
TEST PIT LOG NO. TP-3 Latitude: 42.393677 Longitude: -114.3947449 SILT (ML), light brown to brown (Ft.) variable zones with a slight cemented structure from 3 to 9 ft THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL 621010.GPJ TERRACON2012.GDT 3/23/1 9. moderate to strong cementation from 9 to 9. ft BASALT, black Test Pit Refusal at 9. Feet Test Pit Completed: 3/16/201 Exhibit: A-4
TEST PIT LOG NO. TP-4 Latitude: 42.393066 Longitude: -114.3991699 SILT (ML), light brown to brown, weak cementation from 2 to 3 ft (Ft.) 19 28-2-3 THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL 621010.GPJ TERRACON2012.GDT 3/23/1 moderate cementation below 10 ft 11.3 Test Pit Terminated at 11.3 Feet 10 Test Pit Completed: 3/16/201 Exhibit: A-
TEST PIT LOG NO. TP- Latitude: 42.38704 Longitude: -114.397049 SILT (ML), light brown to brown (Ft.) variable zones with a slight cemented structure from 2 to 11 ft 22 88 THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL 621010.GPJ TERRACON2012.GDT 3/23/1 moderate cementation, trace basalt gravel below 11 ft 11. Test Pit Terminated at 11. Feet 10 Test Pit Completed: 3/16/201 Exhibit: A-6
TEST PIT LOG NO. TP-6 Latitude: 42.38269 Longitude: -114.3992004 SILT (ML), light brown to brown (Ft.) weak cementation from 2 to 3 ft THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL 621010.GPJ TERRACON2012.GDT 3/23/1 9.0 11.3 SANDY SILT (ML), brown, weak to moderate cementation from 9 to 10 ft strong cementation, trace basalt gravel below 10 ft Test Pit Terminated at 11.3 Feet 10 Test Pit Completed: 3/16/201 Exhibit: A-7
TEST PIT LOG NO. TP-7 Latitude: 42.37973 Longitude: -114.3976974 SILT (ML), light brown to brown (Ft.) weak cementation from 2 to 3 ft THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL 621010.GPJ TERRACON2012.GDT 3/23/1 10.0 SANDY SILT (ML), brown, variable zones of weak to moderate cementation 12.0 Test Pit Terminated at 12 Feet 10 Test Pit Completed: 3/16/201 Exhibit: A-8
TEST PIT LOG NO. TP-8 Latitude: 42.386314 Longitude: -114.399808 SILT (ML), light brown to brown (Ft.) weak cementation from 2 to 3 ft THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL 621010.GPJ TERRACON2012.GDT 3/23/1 strong cementation below 11 ft 11. Test Pit Terminated at 11. Feet 10 Test Pit Completed: 3/16/201 Exhibit: A-9
TEST PIT LOG NO. TP-9 Latitude: 42.37796 Longitude: -114.3946991 SILT (ML), light brown to brown (Ft.) variable zones with a slight cemented structure from 2 to 7 ft THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL 621010.GPJ TERRACON2012.GDT 3/23/1 8.2 strong cementation, trace basalt gravel below 7 ft Test Pit Refusal at 8.2 Feet 2 NP 8 Test Pit Completed: 3/16/201 Exhibit: A-10
TEST PIT LOG NO. TP-10 Latitude: 42.387344 Longitude: -114.39134 SILT (ML), light brown to brown (Ft.) weak cementation from 1. to 3 ft THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL 621010.GPJ TERRACON2012.GDT 3/23/1 moderate to stong cementation below 9 ft strong cementation, trace basalt gravel below 10. ft 11.0 Test Pit Refusal at 11 Feet 10 Test Pit Completed: 3/16/201 Exhibit: A-11
APPENDIX B
DESCRIPTION OF SYMBOLS AND ABBREVIATIONS GENERAL NOTES Water Initially Encountered N Standard Penetration Test Resistance (Blows/Ft.) SAMPLING Bulk Sample Water Level After a Specified Period of Time Water Level After a Specified Period of Time Water levels indicated on the soil boring logs are the levels measured in the borehole at the times indicated. Groundwater level variations will occur over time. In low permeability soils, accurate determination of groundwater levels is not possible with short term water level observations. S (HP) (T) (DCP) (PID) (OVA) Hand Penetrometer Torvane Dynamic Cone Penetrometer Photo-Ionization Detector Organic Vapor Analyzer DESCRIPTIVE SOIL CLASSIFICATION Soil classification is based on the Unified Soil Classification System. Coarse Grained Soils have more than 0% of their dry weight retained on a #200 sieve; their principal descriptors are: boulders, cobbles, gravel or sand. Fine Grained Soils have less than 0% of their dry weight retained on a #200 sieve; they are principally described as clays if they are plastic, and silts if they are slightly plastic or non-plastic. Major constituents may be added as modifiers and minor constituents may be added according to the relative proportions based on grain size. In addition to gradation, coarse-grained soils are defined on the basis of their in-place relative density and fine-grained soils on the basis of their consistency. AND ELEVATION NOTES Unless otherwise noted, Latitude and Longitude are approximately determined using a hand-held GPS device. The accuracy of such devices is variable. Surface elevation data annotated with +/- indicates that no actual topographical survey was conducted to confirm the surface elevation. Instead, the surface elevation was approximately determined from topographic maps of the area. RELATIVE DENSITY OF COARSE-GRAINED SOILS (More than 0% retained on No. 200 sieve.) Density determined by Standard Penetration Resistance CONSISTENCY OF FINE-GRAINED SOILS (0% or more passing the No. 200 sieve.) Consistency determined by laboratory shear strength testing, field visual-manual procedures or standard penetration resistance STRENGTH TERMS Descriptive Term (Density) Standard Penetration or N-Value Blows/Ft. Very Loose 0-3 Loose Medium Dense Dense 4-9 10-29 30-0 Descriptive Term (Consistency) Unconfined Compressive Strength Qu, (tsf) Very Soft less than 0.2 0-1 Soft Medium Stiff Stiff 0.2 to 0.0 0.0 to 1.00 1.00 to 2.00 Standard Penetration or N-Value Blows/Ft. 2-4 4-8 8-1 Very Dense > 0 Very Stiff 2.00 to 4.00 1-30 Hard > 4.00 > 30 RELATIVE PROPORTIONS OF SAND AND GRAVEL Descriptive Term(s) of other constituents Percent of Dry Weight Major Component of Sample GRAIN SIZE TERMINOLOGY Particle Size Trace With Modifier < 1 1-29 > 30 Boulders Cobbles Gravel Sand Silt or Clay Over 12 in. (300 mm) 12 in. to 3 in. (300mm to 7mm) 3 in. to #4 sieve (7mm to 4.7 mm) #4 to #200 sieve (4.7mm to 0.07mm Passing #200 sieve (0.07mm) RELATIVE PROPORTIONS OF FINES Descriptive Term(s) of other constituents Trace With Modifier Percent of Dry Weight < - 12 > 12 Term Non-plastic Low Medium High PLASTICITY DESCRIPTION Plasticity Index 0 1-10 11-30 > 30 Exhibit: B-1
UNIFIED SOIL CLASSIFICATION SYSTEM Criteria for Assigning Group Symbols and Group Names Using Laboratory Tests A Coarse Grained Soils: More than 0% retained on No. 200 sieve Fine-Grained Soils: 0% or more passes the No. 200 sieve Gravels: More than 0% of coarse fraction retained on No. 4 sieve Sands: 0% or more of coarse fraction passes No. 4 sieve Silts and Clays: Liquid limit less than 0 Silts and Clays: Liquid limit 0 or more Group Symbol Soil Classification Group Name B Clean Gravels: Cu 4 and 1 Cc 3 E GW Well-graded gravel F Less than % fines C Cu 4 and/or 1 Cc 3 E GP Poorly graded gravel F Gravels with Fines: Fines classify as ML or MH GM Silty gravel F,G,H More than 12% fines C Fines classify as CL or CH GC Clayey gravel F,G,H Clean Sands: Cu 6 and 1 Cc 3 E SW Well-graded sand I Less than % fines D Cu 6 and/or 1 Cc 3 E SP Poorly graded sand I Sands with Fines: Fines classify as ML or MH SM Silty sand G,H,I More than 12% fines D Fines classify as CL or CH SC Clayey sand G,H,I Inorganic: Organic: Inorganic: Organic: PI 7 and plots on or above A line J CL Lean clay K,L,M PI 4 or plots below A line J ML Silt K,L,M Liquid limit - oven dried Organic clay K,L,M,N 0.7 OL Liquid limit - not dried Organic silt K,L,M,O PI plots on or above A line CH Fat clay K,L,M PI plots below A line MH Elastic Silt K,L,M Liquid limit - oven dried Liquid limit - not dried Highly organic soils: Primarily organic matter, dark in color, and organic odor PT Peat 0.7 OH Organic clay K,L,M,P Organic silt K,L,M,Q A Based on the material passing the 3-inch (7-mm) sieve B If field sample contained cobbles or boulders, or both, add with cobbles or boulders, or both to group name. C Gravels with to 12% fines require dual symbols: GW-GM well-graded gravel with silt, GW-GC well-graded gravel with clay, GP-GM poorly graded gravel with silt, GP-GC poorly graded gravel with clay. D Sands with to 12% fines require dual symbols: SW-SM well-graded sand with silt, SW-SC well-graded sand with clay, SP-SM poorly graded sand with silt, SP-SC poorly graded sand with clay E Cu = D 60/D 10 Cc = D (D 10 30 ) 2 x D 60 F If soil contains 1% sand, add with sand to group name. G If fines classify as CL-ML, use dual symbol GC-GM, or SC-SM. H If fines are organic, add with organic fines to group name. I If soil contains 1% gravel, add with gravel to group name. J If Atterberg limits plot in shaded area, soil is a CL-ML, silty clay. K If soil contains 1 to 29% plus No. 200, add with sand or with gravel, whichever is predominant. L If soil contains 30% plus No. 200 predominantly sand, add sandy to group name. M If soil contains 30% plus No. 200, predominantly gravel, add gravelly to group name. N PI 4 and plots on or above A line. O PI 4 or plots below A line. P PI plots on or above A line. Q PI plots below A line.