PZ - Geotechnical Engineering ReportMATERIALS
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GEOTECHNICAL ENGINEERING REPORT
of
Verado West Subdivision
3090 North Locust Grove
Meridian, ID
Prepared for:
C17 Development
4824 West Fairview Avenue
Boise, ID 83706
MTI File Number 13180889g
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Mr. Laren Bailey
C17 Development
4824 West Fairview Avenue
Boise, ID 83706
208-336-5355
Re: Geotechnical Engineering Report
Verado West Subdivision
3090 North Locust Grove
Meridian, ID
Dear Mr. Bailey:
In compliance with your instructions, MTI has conducted a soils exploration and foundation evaluation for the
above referenced development. Fieldwork for this investigation was conducted on 14 June 2018. Data have
been analyzed to evaluate pertinent geotechnical conditions. Results of this investigation, together with our
recommendations, are to be found in the following report. We have provided a PDF copy for your review and
distribution.
Often, questions arise concerning soil conditions because of design and construction details that occur on a
project. MTI would be pleased to continue our role as geotechnical engineers during project implementation.
Additionally, MTI can provide materials testing and special inspection services during construction of this
project. If you will advise us of the appropriate time to discuss these engineering services, we will meet with
you at your convenience.
MTI appreciates this opportunity to be of service to you and looks forward to working with you in the future.
If you have questions, please call (208) 376-4748.
Respectfully Submitted,
Materials Testing & Inspection
Maren Tanberg, E.I.T.
Staff Engineer
�S�pNAL
r E N S, d�
4 14898
Reviewed by: El zabeth Brown, P. G -&(,-/&Q,
Geotechnical Se 'c
Z SET
�U
Reviewed by.- �ontca Sa u es, P.E.
Senior Geotechnical Engineer
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TABLE OF CONTENTS
INTRODUCTION...............................................................................................................................................................3
ProjectDescription.................................................................................................................................................3
Authorization..........................................................................................................................................................3
Purpose...................................................................................................................................................................3
Scopeof Investigation............................................................................................................................................3
Warrantyand Limiting Conditions.........................................................................................................................4
SITEDESCRIPTION..........................................................................................................................................................5
SiteAccess..............................................................................................................................................................5
RegionalGeology...................................................................................................................................................5
GeneralSite Characteristics....................................................................................................................................5
Regional Site Climatology and Geochemistry........................................................................................................6
SEISMICSITE EVALUATION............................................................................................................................................6
GeoseismicSetting.................................................................................................................................................6
SeismicDesign Parameter Values..........................................................................................................................6
SOILSEXPLORATION......................................................................................................................................................8
Exploration and Sampling Procedures....................................................................................................................8
LaboratoryTesting Program...................................................................................................................................8
Soiland Sediment Profile.......................................................................................................................................8
VolatileOrganic Scan.............................................................................................................................................9
SITEHYDROLOGY...........................................................................................................................................................9
Groundwater...........................................................................................................................................................9
SoilInfiltration Rates..............................................................................................................................................9
FOUNDATION, SLAB, AND PAVEMENT DISCUSSION AND RECOMMENDATIONS.............................................................10
FoundationDesign Recommendations.................................................................................................................10
CrawlSpace Recommendations...........................................................................................................................11
Floor, Patio, and Garage Slab-on-Grade...............................................................................................................1
l
Recommended Pavement Sections.......................................................................................................................12
FlexiblePavement Sections..................................................................................................................................12
Common Pavement Section Construction Issues.................................................................................................12
CONSTRUCTIONCONSIDERATIONS...............................................................................................................................13
Earthwork.............................................................................................................................................................13
DryWeather.........................................................................................................................................................14
WetWeather.........................................................................................................................................................14
SoftSubgrade Soils..............................................................................................................................................14
FrozenSubgrade Soils..........................................................................................................................................15
StructuralFill........................................................................................................................................................15
Backfillof Walls...................................................................................................................................................16
Excavations...........................................................................................................................................................16
GroundwaterControl............................................................................................................................................17
GENERALCOMMENTS..................................................................................................................................................17
REFERENCES.................................................................................................................................................................18
APPENDICES.................................................................................................................................................................19
AcronymList........................................................................................................................................................19
GeotechnicalGeneral Notes.................................................................................................................................20
Geotechnical Investigation Test Pit Log...............................................................................................................21
Gravel Equivalent Method — Pavement Thickness Design Procedures................................................................26
R -Value Test Data................................................................................................................................................27
Plate1: Vicinity Map............................................................................................................................................28
Plate2: Site Map...................................................................................................................................................29
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INTRODUCTION
This report presents results of a geotechnical investigation and analysis in support of data utilized in design of
structures as defined in the 2015 International Building Code (IBC). Information in support of groundwater
and stormwater issues pertinent to the practice of Civil Engineering is included. Observations and
recommendations relevant to the earthworlc phase of the project are also presented. Revisions in plans or
drawings for the proposed development from those enumerated in this report should be brought to the attention
of the soils engineer to determine whether changes in the provided recommendations are required. Deviations
from noted subsurface conditions, if encountered during construction, should also be brought to the attention of
the soils engineer.
Project Description
The proposed development is in the central portion of the City of Meridian, Ada County, ID, and occupies a
portion of the NW'/4NWt/4 of Section 5, Township 3 North, Range 1 East, Boise Meridian. This project will
consist of construction of roughly 134 residential lots. The development is approximately 17.35 acres in size.
Total settlements are limited to 1 inch. Loads of up to 4,000 pounds per lineal foot for wall footings, and column
loads of up to 50,000 pounds were assumed for settlement calculations. Additionally, assumptions have been
made for traffic loading of pavements. Retaining walls are not anticipated as part of the project. MTI has not
been informed of the proposed grading plan.
Authorization
Authorization to perform this exploration and analysis was given in the form of a written authorization to
proceed from Mr. Laren Bailey of C17 Development to Maren Tanberg of Materials Testing and Inspection
(MTI), on 2 June 2018. Said authorization is subject to terms, conditions, and limitations described in the
Professional Services Contract entered into between C17 Development and MTI. Our scope of services for the
proposed development has been provided in our proposal dated 7 May 2018 and repeated below.
Purpose
The purpose of this Geotechnical Engineering Report is to determine various soil profile components and their
engineering characteristics for use by either design engineers or architects in:
• Preparing or verifying suitability of foundation design and placement
• Preparing site drainage designs
• Indicating issues pertaining to earthwork construction
• Preparing residential pavement section design requirements
Scope of Investigation
The scope of this investigation included review of geologic literature and existing available geotechnical studies
of the area, visual site reconnaissance of the immediate site, subsurface exploration of the site, field and
laboratory testing of materials collected, and engineering analysis and evaluation of foundation materials.
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Warranty and Limiting Conditions
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❑ Soecial
MTI warrants that findings and conclusions contained herein have been formulated in accordance with generally
accepted professional engineering practice in the fields of foundation engineering, soil mechanics, and
engineering geology only for the site and project described in this report. These engineering methods have been
developed to provide the client with information regarding apparent or potential engineering conditions relating
to the site within the scope cited above and are necessarily limited to conditions observed at the time of the site
visit and research. Field observations and research reported herein are considered sufficient in detail and scope
to form a reasonable basis for the purposes cited above.
Exclusive Use
This report was prepared for exclusive use of the property owner(s), at the time of the report, and their
retained design consultants ("Client"). Conclusions and recommendations presented in this report are based
on the agreed-upon scope of work outlined in this report together with the Contract for Professional Services
between the Client and Materials Testing and Inspection ("Consultant"). Use or misuse of this report, or reliance
upon findings hereof, by parties other than the Client is at their own risk. Neither Client nor Consultant make
representation of warranty to such other parties as to accuracy or completeness of this report or suitability of its
use by such other parties for purposes whatsoever, known or unknown, to Client or Consultant. Neither Client
nor Consultant shall have liability to indemnify or hold harmless third parties for losses incurred by actual or
purported use or misuse of this report. No other warranties are implied or expressed.
Report Recommendations are Limited and Subiect to Misinterpretation
There is a distinct possibility that conditions may exist that could not be identified within the scope of the
investigation or that were not apparent during our site investigation. Findings of this report are limited to data
collected from noted explorations advanced and do not account for unidentified fill zones, unsuitable soil types
or conditions, and variability in soil moisture and groundwater conditions. To avoid possible misinterpretations
of findings, conclusions, and implications of this report, MTI should be retained to explain the report contents
to other design professionals as well as construction professionals.
Since actual subsurface conditions on the site can only be verified by earthwork, note that construction
recommendations are based on general assumptions from selective observations and selective field exploratory
sampling. Upon commencement of construction, such conditions may be identified that require corrective
actions, and these required corrective actions may impact the project budget. Therefore, construction
recommendations in this report should be considered preliminary, and MTI should be retained to observe actual
subsurface conditions during earthwork construction activities to provide additional construction
recommendations as needed.
Since geotechnical reports are subject to misinterpretation, do not separate the soil logs from the report. Rather,
provide a copy of, or authorize for their use, the complete report to other design professionals or contractors.
Locations of exploratory sites referenced within this report should be considered approximate locations only.
For more accurate locations, services of a professional land surveyor are recommended.
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This report is also limited to information available at the time it was prepared. In the event additional
information is provided to MTI following publication of our report, it will be forwarded to the client for
evaluation in the form received.
Environmental Concerns
Comments in this report concerning either onsite conditions or observations, including soil appearances and
odors, are provided as general information. These comments are not intended to describe, quantify, or evaluate
environmental concerns or situations. Since personnel, skills, procedures, standards, and equipment differ, a
geotechnical investigation report is not intended to substitute for a geoenvironmental investigation or a Phase
II/III Environmental Site Assessment. If environmental services are needed, MTI can provide, via a separate
contract, those personnel who are trained to investigate and delineate soil and water contamination.
SITE DESCRIPTION
Site Access
Access to the site may be gained via Interstate 84 to the Eagle Road exit. Proceed north on Eagle Road
approximately 2.5 miles to its intersection with Ustick Road. From this intersection, proceed west 1.0 mile to
Locust Grove Road. The site occupies the southeast corner of this intersection. Presently the site exists as a
vacant residence with associated outbuildings and pasture land fronting Ustick Road. The location is depicted
on site map plates included in the Appendix.
Regional Geology
The project site is located within the western Snake River Plain of southwestern Idaho and eastern Oregon. The
plain is a northwest trending rift basin, about 45 miles wide and 200 miles long, that developed about 14 million
years ago (Ma) and has since been occupied sporadically by large inland lakes. Geologic materials found within
and along the plain's margins reflect volcanic and fluvial/lacustrine sedimentary processes that have led to an
accumulation of approximately I to 2 km of interbedded volcanic and sedimentary deposits within the
plain. Along the margins of the plain, streams that drained the highlands to the north and south provided coarse
to fine-grained sediments eroded from granitic and volcanic rocks, respectively. About 2 million years ago the
last of the lakes was drained and since that time fluvial erosion and deposition has dominated the evolution of
the landscape. The project site is underlain by the "Gravel of Whitney Terrace" as mapped by Othberg and
Stanford (1993). Sediments of the Whitney terrace consist of sandy pebble and cobble gravel. The Whitney
terrace is the second terrace above modern Boise River floodplain, is thickest toward its eastern extent, and is
mantled with 2-6 feet of loess.
General Site Characteristics
This proposed development consists of approximately 17.35 acres of relatively flat terrain. Bisecting the
property from east to west is a small irrigation ditch. In the southeast portion of the site, the South Slough cuts
through the corner of the property. Throughout the majority of the site, surficial soils consist of lean clays and
silts. Vegetation primarily consists of mature trees, bunchgrass, and other native grass varieties typical of and
to semi -arid environments.
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Regional drainage is north toward the Boise River. Stormwater drainage for the site is achieved by percolation
through surficial soils. The site is situated so that it is unlikely that it will receive any stormwater drainage from
off-site sources. Stormwater drainage collection and retention systems are not in place on the project site, but
currently exist along Locust Grove Road and Ustick Road in the form of curbs and drop inlets.
Regional Site Climatology and Geochemistry
According to the Western Regional Climate Center, the average precipitation for the Treasure Valley is on the
order of 10 to 12 inches per year, with an annual snowfall of approximately 20 inches and a range from 3 to 49
inches. The monthly mean daily temperatures range from 21°F to 95°F, with daily extremes ranging from -
25°F to 111°F. Winds are generally from the northwest or southeast with an annual average wind speed of
approximately 9 miles per hour (mph) and a maximum of 62 mph. Soils and sediments in the area are primarily
derived from siliceous materials and exhibit low electro -chemical potential for corrosion of metals or concretes.
Local aggregates are generally appropriate for Portland cement and lime cement mixtures. Surface water,
groundwater, and soils in the region typically have pH levels ranging from 7.2 to 8.2.
SEISMIC SITE EVALUATION
Geoseismic Setting
Soils on site are classed as Site Class D in accordance with Chapter 20 of the American Society of Civil
Engineers (ASCE) publication ASCE/SEI 7-10. Structures constructed on this site should be designed per IBC
requirements for such a seismic classification. Our investigation did not reveal hazards resulting from potential
earthquake motions including: slope instability, liquefaction, and surface rupture caused by faulting or lateral
spreading. Incidence and anticipated acceleration of seismic activity in the area is low.
Seismic Design Parameter Values
The United States Geological Survey National Seismic Hazard Maps (2008), includes a peals ground
acceleration map. The map for 2% probability of exceedance in 50 years in the Western United States in
standard gravity (g) indicates that a peals ground acceleration of 0.200 is appropriate for the project site based
on a Site Class D.
The following section provides an assessment of the earthquake -induced earthquake loads for the site, including
identification of the earthquake spectral response acceleration for short periods, SAfs, and at 1 -second period,
SATI, adjusted for site class effects as required by the 2015 IBC based on the following equations:
Saes = F,, SS
S,a,11 = F,,S,
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Where:
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FQ = Site coefficient defined in Table 1613.3.3(1) in the 2015 IBC.
F,, = Site coefficient defined in Table 1613.3.3(2) in the 2015 IBC.
Ss = The mapped spectral accelerations for short periods.
S1= The mapped spectral accelerations for 1 -second periods.
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The USGS National Seismic Hazards Mapping Project includes a program that provides values for ground
motion at a selected site based on the same data that were used to prepare the USGS ground motion maps. The
maps were developed using attenuation relationships for soft rock sites; the source model, assumptions, and
empirical relationships used in preparation of the maps are described in Petersen and others (1996). The
following values are based on a site specific Site Class of D.
SS and S1 = Mapped Spectral Acceleration Values
Site Class D
Fa= 1.564
Fv = 2.387
Period (sec) S. (g)
0.2 0.295 (SS, Site Class D)
1.0 0.103 (S 1, Site Class D)
Sms = 0.462
S,m = 0.247
Design spectral response acceleration parameters as presented in the 2015 IBC are defined as a 5% damped
design spectral response acceleration at short periods, SDs, and at 1 -second period, SDI, as calculated from the
following equations:
2
SDs = 3 Secs
SDI2
= 3 Ser►
For the proposed project site, the 5% damped design spectral response acceleration at short periods, as
calculated using the program supplied by the USGS are as follows:
SDs = 0.308
SDI = 0.164
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SOILS EXPLORATION
Exploration and Sampling Procedures
Field exploration conducted to determine engineering characteristics of subsurface materials included a
reconnaissance of the project site and investigation by test pit. Test pit sites were located in the field by means
of a Global Positioning System (GPS) device and are reportedly accurate to within fifteen feet. Upon
completion of investigation, each test pit was backfilled with loose excavated materials. Re -excavation and
compaction of these test pit areas are required prior to construction of overlying structures.
In addition, samples were obtained from representative soil strata encountered. Samples obtained have been
visually classified in the field by professional staff, identified according to test pit number and depth, placed in
sealed containers, and transported to our laboratory for additional testing. Subsurface materials have been
described in detail on logs provided in the Appendix. Results of field and laboratory tests are also presented in
the Appendix. MTI recommends that these logs not be used to estimate fill material quantities.
Laboratory Testing Program
Along with our field investigation, a supplemental laboratory testing program was conducted to determine
additional pertinent engineering characteristics of subsurface materials necessary in an analysis of anticipated
behavior of the proposed structures. Laboratory tests were conducted in accordance with current applicable
American Society for Testing and Materials (ASTM) specifications, and results of these tests are to be found
on the accompanying logs located in the Appendix. The laboratory testing program for this report included:
Atterberg Limits Testing — ASTM D4318 and Grain Size Analysis — ASTM CI 17/C136.
Soil and Sediment Profile
The profile below represents a generalized interpretation for the project site. Note that on site soils strata,
encountered between test pit locations, may vary from the individual soil profiles presented in the logs, which
can be found in the Appendix.
The materials encountered during exploration were quite typical for the geologic area mapped as Gravel of
Whitney Terrace. Lean clay and silt soils were encountered at surface. The silt and lean clay soils were brown
to dark brown, dry, very stiff to hard, and in some cases, contained fine-grained sand. Below the surficial soils
was sandy silt. The sandy silt was brown, dry, stiff to hard, and contained fine to coarse-grained sand and
varying degrees of calcium carbonate cementation. At depth, poorly graded gravel with sand was encountered.
The poorly graded gravel with sand was reddish brown to light brown, dry, dense to very dense, and contained
fine to coarse-grained sand, fine to coarse gravel, and 12 -inch -minus cobbles. Silt was noted in the upper foot
of this strata.
During excavation, test pit sidewalls were generally stable. In general, fine grained soils remained stable while
more granular sediments more readily sloughed. However, moisture contents will affect wall competency with
saturated soils having a tendency to readily slough when under load and unsupported.
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Volatile Organic Scan
No environmental concerns were identified prior to commencement of the investigation. Therefore, soils
obtained during on-site activities were not assessed for volatile organic compounds by portable photoionization
detector. Samples obtained during our exploration activities exhibited no odors or discoloration typically
associated with this type of contamination. No groundwater was encountered.
SITE HYDROLOGY
Existing surface drainage conditions are defined in the General Site Characteristics section. Information
provided in this section is limited to observations made at the time of the investigation. Either regional or local
ordinances may require information beyond the scope of this report.
Groundwater
During this field investigation, groundwater was not encountered in test pits advanced to a maximum depth of
15.4 feet bgs. In the vicinity of the project site, groundwater levels are controlled in large part by residential
and agricultural irrigation activity and leakage from nearby canals. Maximum groundwater elevations likely
occur during the later portion of the irrigation season.
During previous investigations performed in July 2016 and August 2017 within approximately %3 -mile to the
north of the project site, groundwater was not encountered in test pits advanced to depths as great as 15.5 feet
bgs. In September 2014 roughly'/4-mile to the south, groundwater was noted in one test pit advanced to a depth
of 16.0 feet bgs. Furthermore, according to United States Geological Survey (USGS) monitoring well data
within approximately'/4-mile of the project site, groundwater was measured at a depth of 16.0 feet bgs, which
equates to a groundwater elevation of 2,589 feet above mean sea level (msl).
For construction purposes, groundwater depth can be assumed to remain greater than 15 feet bgs throughout the
year. Since this is an estimated depth and seasonal groundwater levels fluctuate, actual levels should be
confirmed by periodic groundwater data collected from piezometers installed in all of the test pits. If desired,
MTI is available to perform this monitoring.
Soil Infiltration Rates
Soil permeability, which is a measure of the ability of a soil to transmit a fluid, was not tested in the field. Given
the absence of direct measurements, for this report an estimation of infiltration is presented using generally
recognized values for each soil type and gradation. Of soils comprising the generalized soil profile for this
study, lean clay, silt, and silt with sand soils generally offer little permeability, with typical hydraulic infiltration
rates of less than 2 inches per hour. Sandy silt soils will commonly exhibit infiltration rates from 2 to 4 inches
per hour; though calcium carbonate cementation may reduce this value to near zero. Poorly graded gravel
sediments typically exhibit infiltration values in excess of 12 inches per hour. Infiltration testing is generally
not required within these sediments because of their free -draining nature.
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It is recommended that infiltration facilities constructed on the site be extended into native, silt -free poorly
graded gravel with sand sediments. Excavation depths of approximately 5.0 to 10.0 feet bgs should be
anticipated to expose these silt -free poorly graded gravel with sand sediments. Because of the high soil
permeability, ASTM C33 filter sand, or equivalent, should be incorporated into design of infiltration facilities.
An infiltration rate of 8 inches per hour should be used in design. Actual infiltration rates should be confirmed
at the time of construction.
FOUNDATIONS SLABS AND PAVEMENT DISCUSSION AND RECOMMENDATIONS
Various foundation types have been considered for support of the proposed development. Two requirements
must be met in the design of foundations. First, the applied bearing stress must be less than the ultimate bearing
capacity of foundation soils to maintain stability. Second, total and differential settlement must not exceed an
amount that will produce an adverse behavior of the superstructure. Allowable settlement is usually exceeded
before bearing capacity considerations become important; thus, allowable bearing pressure is normally
controlled by settlement considerations.
Considering subsurface conditions and the proposed construction, it is recommended that the development be
founded upon conventional spread footings and continuous wall footings. Total settlements should not exceed
1 inch if the following design and construction recommendations are observed. Presently, there are
approximately 134 lots proposed for the project site. The following recommendations are not specific to the
individual structures but rather should be viewed as guidelines for the subdivision — wide development.
Foundation Design Recommendations
Based on data obtained from the site and test results from various laboratory tests performed, MTI recommends
the following guidelines for the net allowable soil bearing capacity:
Soil Bearing Capacity
Footing Depth
ASTM D1557
Sub rade Compaction
Net Allowable
Soil Bearing Capacity
Footings must bear on competent, undisturbed,
1,5001bs/fe
native lean clay soils, silt soils, silt with sand soils,
sandy silt soils or compacted structural fill. Existing
Not Required for Native
A %3 increase is allowable
organic materials and fill materials (if encountered)
Soil
for short-term loading,
must be completely removed from below foundation
which is defined by seismic
elements.' Excavation depths ranging from roughly
95% for Structural Fill
events or designed wind
1.0 to 2.5 feet bgs should be anticipated to expose
speeds.
proper bearing soils.
'It will be required for MTI personnel to verify the bearing soil suitability for each structure at the time of construction.
ZDepending on the time of year construction takes place the subgrade soils may be unstable because of high moisture
contents If unstable conditions are encountered over -excavation and replacement with granular structural full and/or use
of geotextiles maberequired.
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The following sliding frictional coefficient values should be used: 1) 0.35 for footings bearing on native
clay/silt/silt with sand/sandy silt soils and 2) 0.45 for footings bearing on granular structural fill. A passive
lateral earth pressure of 337 pounds per square foot per foot (psf/ft) should be used for clay/silt/silt with
sand/sandy silt soils. For compacted sandy gravel fill, a passive lateral earth pressure of 496 psf/ft should be
used.
Footings should be proportioned to meet either the stated soil bearing capacity or the 2015 IBC minimum
requirements. Total settlement should be limited to approximately I inch, and differential settlement should be
limited to approximately %2 inch. Objectionable soil types encountered at the bottom of footing excavations
should be removed and replaced with structural fill. Excessively loose or soft areas that are encountered in the
footings subgrade will require over -excavation and backfilling with structural fill. To minimize the effects of
slight differential movement that may occur because of variations in the character of supporting soils and
seasonal moisture content, MTI recommends continuous footings be suitably reinforced to make them as rigid
as possible. For frost protection, the bottom of external footings should be 24 inches below finished grade.
Crawl Space Recommendations
Considering the presence of shallow cemented soils and across the site, all residences constructed with crawl
spaces should be designed in a manner that will inhibit water in the crawl spaces. MTI recommends that roof
drains carry stormwater at least 10 feet away from each residence. Grades should be at least 5 percent for a
distance of 10 feet away from all residences. In addition, rain gutters should be placed around all sides of
residences, and backfill around stem walls should be placed and compacted in a controlled manner.
Floor, Patio, and Garage Slab -on -Grade
Organic, loose, or obviously compressive materials must be removed prior to placement of concrete floors or
floor -supporting fill. In addition, the remaining subgrade should be treated in accordance with guidelines
presented in the Earthwork section. Areas of excessive yielding should be excavated and backfilled with
structural fill. Fill used to increase the elevation of the floor slab should meet requirements detailed in the
Structural Fill section. Fill materials must be compacted to a minimum 95 percent of the maximum dry density
as determined by ASTM D1557.
A free -draining granular mat (drainage fill course) should be provided below slabs -on -grade. This should be a
minimum of 4 inches in thickness and properly compacted. The mat should consist of a sand and gravel mixture,
complying with Idaho Standards for Public Works Construction (ISPWC) specifications for 3/4 -inch (Type 1)
crushed aggregate. The granular mat should be compacted to no less than 95 percent of the maximum dry
density as determined by ASTM D1557. A moisture -retarder should be placed beneath floor slabs to minimize
potential ground moisture effects on moisture -sensitive floor coverings. The moisture -retarder should be at
least 15 -mil in thickness and have a permeance of less than 0.01 US perms as determined by ASTM E96.
Placement of the moisture -retarder will require special consideration with regard to effects on the slab -on -grade
and should adhere to recommendations outlined in the ACI 302.1R and ASTM E1745 publications. Upon
request, MTI can provide further consultation regarding installation.
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Recommended Pavement Sections
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As required by Ada County Highway District (ACRD), MTI has used a traffic index of 6 to determine the
necessary pavement cross-section for the site. MTI has made assumptions for traffic loading variables based
on the character of the proposed construction. The Client should review these assumptions to make sure they
reflect intended use and loading of pavements both now and in the future. MTI collected a sample of near -
surface soils for Resistance Value (R -value) testing representative of soils to depths of 2 feet below existing
ground surface. This sample, consisting of silt with sand collected from test pit 2, yielded a R -value of 5. The
following are minimum thickness requirements for assured pavement function. Depending on site conditions,
additional work, e.g. soil preparation, may be required to support construction equipment. These have been
listed within the Soft Subgrade Soils section. Results of the test are graphically depicted in the Appendix.
Flexible Pavement Section
The Gravel Equivalent Method, as defined in Section 500 of the State of Idaho Department of Transportation
(ITD) Materials Manual, was used to develop the pavement section. ACHD parameters for traffic index and
substitution ratios, which were obtained from the ACRD Policy Manual, were also used in the design. A
calculation sheet provided in the Appendix indicates the soils constant, traffic loading, traffic projections, and
material constants used to calculate the pavement section. MTI recommends that materials used in the
construction of asphaltic concrete pavements meet the requirements of the ISPWC Standard Specification for
Highway Construction. Construction of the pavement section should be in accordance with these specifications
and should adhere to guidelines recommended in the section on Construction Considerations.
Gravel Equivalent Method Flexible Pavement Specifications
Pavement Section Component' I Roadway Section
Asphaltic Concrete 2.5 Inches
Crushed Aggregate Base 4.0 Inches
Structural Subbase 14.0 Inches
Compacted Subgrade Not Required for Native Soils
'It will be required for MTI personnel to verify subgrade competency at the time of construction.
Asphaltic Concrete: Asphalt mix design shall meet the requirements of ISPWC, Section 810 Class III plant
mix. Materials shall be placed in accordance with ISPWC Standard Specifications for
Highway Construction.
Aggregate Base: Material complying with ISPWC Standards for Crushed Aggregate Materials.
Structural Subbase: Material complying with requirements for granular structural fill (uncrushed) as
defined in ISPWC.
Common Pavement Section Construction Issues
The subgrade upon which above pavement sections are to be constructed must be properly stripped, inspected,
and proof -rolled. Proof rolling of subgrade soils should be accomplished using a heavy rubber -tired, fully
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loaded, tandem -axle dump truck or equivalent. Verification of subgrade competence by MTI personnel at the
time of construction is required. Fill materials on the site must demonstrate the indicated compaction prior to
placing material in support of the pavement section. MTI anticipated that pavement areas will be subjected to
moderate traffic. Subgrade clays and silts near and above optimum moisture contents may pump during
compaction. Pumping or soft areas must be removed and replaced with structural fill.
Fill material and aggregates, as well as compacted native subgrade soils, in support of the pavement section
must be compacted to no less than 95 percent of the maximum dry density as determined by ASTM D698 for
flexible pavements and by ASTM D1557 for rigid pavements. If a material placed as a pavement section
component cannot be tested by usual compaction testing methods, then compaction of that material must be
approved by observed proof rolling. Minor deflections from proof rolling for flexible pavements are allowable.
Deflections from proof rolling of rigid pavement support courses should not be visually detectable.
MTI recommends that rigid concrete pavement be provided for heavy garbage receptacles. This will eliminate
damage caused by the considerable loading transferred through the small steel wheels onto asphaltic concrete.
Rigid concrete pavement should consist of Portland Cement Concrete Pavement (PCCP) generally adhering to
ITD specifications for Urban Concrete. PCCP should be 6 inches thick on a 4 -inch drainage fill course (see
Floor Slab -on -Grade section), and should be reinforced with welded wire fabric. Control joints must be on
12 -foot centers or less.
CONSTRUCTION CONSIDERATIONS
Recommendations in this report are based upon structural elements of the project being founded on competent,
native lean clay, silt, silt with sand, sandy silt soils or compacted structural fill. Structural areas should be
stripped to an elevation that exposes these soil types.
Earthwork
Excessively organic soils, deleterious materials, or disturbed soils generally undergo high volume changes when
subjected to loads, which is detrimental to subgrade behavior in the area of pavements, floor slabs, structural
fills, and foundations. Mature trees, brush, and thick grasses with associated root systems were noted at the
time of our investigation. It is recommended that organic or disturbed soils, if encountered, be removed to
depths of 1 foot (minimum), and wasted or stockpiled for later use. However, in areas where trees are/were
present, deeper excavation depths should be anticipated. Stripping depths should be adjusted in the field to
assure that the entire root zone or disturbed zone or topsoil are removed prior to placement and compaction of
structural fill materials. Exact removal depths should be determined during grading operations by MTI
personnel, and should be based upon subgrade soil type, composition, and firmness or soil stability. If
underground storage tanks, underground utilities, wells, or septic systems are discovered during construction
activities, they must be decommissioned then removed or abandoned in accordance with governing Federal,
State, and local agencies. Excavations developed as the result of such removal must be backfilled with structural
fill materials as defined in the Structural Fill section.
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MTI should oversee subgrade conditions (i.e., moisture content) as well as placement and compaction of new
fill (if required) after native soils are excavated to design grade. Recommendations for structural fill presented
in this report can be used to minimize volume changes and differential settlements that are detrimental to the
behavior of footings, pavements, and floor slabs. Sufficient density tests should be performed to properly
monitor compaction. For structural fill beneath building structures, one in-place density test per lift for every
5,000 square feet is recommended. In parking and driveway areas, this can be decreased to one test per lift for
every 10,000 square feet.
Dry Weather
If construction is to be conducted during dry seasonal conditions, many problems associated with soft soils may
be avoided. However, some rutting of subgrade soils may be induced by shallow groundwater conditions related
to springtime runoff or irrigation activities during late summer through early fall. Solutions to problems
associated with soft subgrade soils are outlined in the Soft Subgrade Soils section. Problems may also arise
because of lack of moisture in native and fill soils at time of placement. This will require the addition of water
to achieve near -optimum moisture levels. Low -cohesion soils exposed in excavations may become friable,
increasing chances of sloughing or caving. Measures to control excessive dust should be considered as part of
the overall health and safety management plan.
Wet Weather
If construction is to be conducted during wet seasonal conditions (commonly from mid-November through
May), problems associated with soft soils must be considered as part of the construction plan. During this time
of year, fine-grained soils such as silts and clays will become unstable with increased moisture content, and
eventually deform or rut. Additionally, constant low temperatures reduce the possibility of drying soils to near
optimum conditions.
Soft Subgrade Soils
Shallow fine-grained subgrade soils that are high in moisture content should be expected to pump and rut under
construction traffic. During periods of wet weather, construction may become very difficult if not impossible.
The following recommendations and options have been included for dealing with soft subgrade conditions:
Track -mounted vehicles should be used to strip the subgrade of root matter and other deleterious debris.
Heavy rubber -tired equipment should be prohibited from operating directly on the native subgrade and
areas in which structural fill materials have been placed. Construction traffic should be restricted to
designated roadways that do not cross, or cross on a limited basis, proposed roadway or parking areas.
Soft areas can be over -excavated and replaced with granular structural fill.
Construction roadways on soft subgrade soils should consist of a minimum 2 -foot thickness of large
cobbles of 4 to 6 inches in diameter with sufficient sand and fines to fill voids. Construction entrances
should consist of a 6 -inch thickness of clean, 2 -inch minimum, angular drain -rock and must be a
minimum of 10 feet wide and 30 to 50 feet long. During the construction process, top dressing of the
entrance may be required for maintenance.
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Scarification and aeration of subgrade soils can be employed to reduce the moisture content of wet
subgrade soils. After stripping is complete, the exposed subgrade should be ripped or disked to a depth
of 1'/2 feet and allowed to air dry for 2 to 4 weeks. Further disking should be performed on a weekly
basis to aid the aeration process.
Alternative soil stabilization methods include use of geotextiles, lime, and cement stabilization. MTI is
available to provide recommendations and guidelines at your request.
Frozen Subgrade Soils
Prior to placement of structural fill materials or foundation elements, frozen subgrade soils must either be
allowed to thaw or be stripped to depths that expose non -frozen soils and wasted or stockpiled for later use.
Stockpiled materials must be allowed to thaw and return to near -optimal conditions prior to use as structural
fill.
The onsite, shallow lean clay and silt soils are susceptible to frost heave during freezing temperatures. For
exterior flatwork and other structural elements, adequate drainage away from subgrades is critical. Compaction
and use of structural fill will also help to mitigate the potential for frost heave. Complete removal of frost
susceptible soils for the full frost depth, followed by replacement with a non -frost susceptible structural fill, can
also be used to mitigate the potential for frost heave. MTI is available to provide further guidance/assistance
upon request.
Structural Fill
Soils recommended for use as structural fill are those classified as GW, GP, SW, and SP in accordance with the
Unified Soil Classification System (USCS) (ASTM D2487). Use of silty soils (USCS designation of GM, SM,
and ML) as structural fill may be acceptable. However, use of silty soils (GM SM and ML) as structural fill
below footings is prohibited. These materials require very high moisture contents for compaction and require
a long time to dry out if natural moisture contents are too high and may also be susceptible to frost heave under
certain conditions. Therefore, these materials can be quite difficult to work with as moisture content, lift
thickness, and compactive effort becomes difficult to control. If silty soil is used for structural fill, lift
thicknesses should not exceed 6 inches (loose) and fill material moisture must be closely monitored at both the
working elevation and the elevations of materials already placed. Following placement, silty soils must be
protected from degradation resulting from construction traffic or subsequent construction.
Recommended granular structural fill materials, those classified as GW, GP, SW, and SP, should consist of a
6 -inch minus select, clean, granular soil with no more than 50 percent oversize (greater than %-inch) material
and no more than 12 percent fines (passing No. 200 sieve). These fill materials should be placed in layers not
to exceed 12 inches in loose thickness. Prior to placement of structural fill materials, surfaces must be prepared
as outlined in the Construction Considerations section. Structural fill material should be moisture -conditioned
to achieve optimum moisture content prior to compaction. For structural fill below footings, areas of compacted
backfill must extend outside the perimeter of the footings for a distance equal to the thickness of fill between
the bottom of foundation and underlying soils, or 5 feet, whichever is less. All fill materials must be monitored
during placement and tested to confirm compaction requirements, outlined below, have been achieved.
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Each layer of structural fill must be compacted, as outlined below:
Below Structures and Rigid Pavements: A minimum of 95 percent of the maximum dry density as
determined by ASTM D1557.
Below Flexible Pavements: A minimum of 92 percent of the maximum dry density as determined by
ASTM D1557 or 95 percent of the maximum dry density as determined by ASTM D698.
The ASTM D1557 test method must be used for samples containing up to 40 percent oversize (greater than %-
inch) particles. If material contains more than 40 percent but less than 50 percent oversize particles, compaction
of fill must be confirmed by proof rolling each lift with a 10 -ton vibratory roller (or equivalent) until the
maximum density has been achieved. Density testing must be performed after each proof rolling pass until the
in-place density test results indicate a drop (or no increase) in the dry density, defined as maximum density or
"break over" point. The number of required passes should be used as the requirements on the remainder of fill
placement. Material should contain sufficient fines to fill void spaces, and must not contain more than 50
percent oversize particles.
Backfill of Walls
Backfill materials must conform to the requirements of structural fill, as defined in this report. For wall heights
greater than 2.5 feet, the maximum material size should not exceed 4 inches in diameter. Placing oversized
material against rigid surfaces interferes with proper compaction, and can induce excessive point loads on walls.
Backfill shall not commence until the wall has gained sufficient strength to resist placement and compaction
forces. Further, retaining walls above 2.5 feet in height shall be backfilled in a manner that will limit the
potential for damage from compaction methods and/or equipment. It is recommended that only small hand -
operated compaction equipment be used for compaction of backfill within a horizontal distance equal to the
height of the wall, measured from the back face of the wall.
Backfill should be compacted in accordance with the specifications for structural fill, except in those areas
where it is determined that future settlement is not a concern, such as planter areas. In nonstructural areas,
backfill must be compacted to a firm and unyielding condition.
Excavations
Shallow excavations that do not exceed 4 feet in depth may be constructed with side slopes approaching vertical.
Below this depth, it is recommended that slopes be constructed in accordance with Occupational Safety and
Health Administration (OSHA) regulations, Section 1926, Subpart P. Based on these regulations, on-site soils
are classified as type "C" soil, and as such, excavations within these soils should be constructed at a maximum
slope of I Meet horizontal to 1 foot vertical (1%:1) for excavations up to 20 feet in height. Excavations in
excess of 20 feet will require additional analysis. Note that these slope angles are considered stable for short-
term conditions only, and will not be stable for long-term conditions.
During the subsurface exploration, test pit sidewalls generally exhibited little indication of collapse; however,
sloughing of fill materials and native granular sediments from test pit sidewalls was observed. For deep
excavations, native granular sediments cannot be expected to remain in position. These materials are prone to
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failure and may collapse, thereby undermining upper soil layers. This is especially true when excavations
approach depths near the water table. Care must be taken to ensure that excavations are properly backfilled in
accordance with procedures outlined in this report.
Groundwater Control
Groundwater is anticipated to be below the depth of most construction. Excavations below the water table will
require a dewatering program. Special precautions may be required for control of surface runoff and subsurface
seepage. It is recommended that runoff be directed away from open excavations. Silty and clayey soils may
become soft and pump if subjected to excessive traffic during time of surface runoff. Ponded water in
construction areas should be drained through methods such as trenching, sloping, crowning grades, nightly
smooth drum rolling, or installing a French drain system. Additionally, temporary or permanent driveway
sections should be constructed if extended wet weather is forecasted.
GENERAL COMMENTS
Based on the subsurface conditions encountered during this investigation and available information regarding
the proposed development, the site is adequate for the planned construction. When plans and specifications are
complete and if significant changes are made in the character or location of the proposed structure, consultation
with MTI must be arranged as supplementary recommendations may be required. Suitability of subgrade soils
and compaction of structural fill materials must be verified by MTI personnel prior to placement of structural
elements. Additionally, monitoring and testing should be performed to verify that suitable materials are used
for structural fill and that proper placement and compaction techniques are utilized.
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REFERENCES
American Concrete Institute (ACI) (2015). Guide for Concrete Floor and Slab Construction: ACI 302.1R. Farmington Hills, MI: ACI.
American Society of Civil Engineers (ASCE) (2013). Minimum Design Loads for Buildings and Other Structures: ASCE/SEI 7-10.
Reston, VA: ASCE.
American Society for Testing and Materials (ASTM) (2013). Standard Test Method for Materials Finer than 75-µm (No. 200) Sieve
in Mineral Aggregates by Washing: ASTM C117. West Conshohocken, PA: ASTM.
American Society for Testing and Materials (ASTM) (2014). Standard Test Method for Sieve Analysis of Fine and Coarse Aggregates:
ASTM C136. West Conshohocken, PA: ASTM.
American Society for Testing and Materials (ASTM) (2012). Standard Test Methods for Laboratory ompaction Characteristics of
Soil Using Standard Effort: ASTM D698. West Conshohocken, PA: ASTM.
American Society for Testing and Materials (ASTM) (2012). Standard Test Methods for Laboratoryompaction Characteristics of
Soil Using Modified Effort: ASTM D1557. West Conshohocken, PA: ASTM.
American Society for Testing and Materials (ASTM) (2013). Standard Test Methods for Resistance Value (R -Value) and Expansion
Pressure of Compacted Soils: ASTM D2844. West Conshohocken, PA: ASTM.
American Society for Testing and Materials (ASTM) (2011). Standard Practice for Classification of Soils for Engineering Purposes
(Unified Soil Classification System): ASTM D2487. West Conshohocken, PA: ASTM.
American Society for Testing and Materials (ASTM) (2010). Standard Test Methods for Liquid Limit, Plastic Limit, and Plasticity
Index of Soils: ASTM D4318. West Conshohocken, PA: ASTM.
American Society for Testing and Materials (ASTM) (2011). Standard Specification for Plastic Water Vapor Retarders Used in
Contact with Soil or Granular Fill Under Concrete Slabs: ASTM E1745. West Conshohocken, PA: ASTM.
Desert Research Institute. Western Regional Climate Center. [Online] Available: <http://www.wrcc.dri.edu/> (2018).
International Building Code Council (2015). International Building Code, 2015. Country Club Hills, IL: Author.
Local Highway Technical Assistance Council (LHTAC) (2017). Idaho Standards for Public Works Construction, 2017. Boise, ID:
Author.
Othberg, K. L. and Stanford, L. A., Idaho Geologic Society (1992). Geologic Map of the Boise Valley and Adjoining Area, Western
Snake River Plain Idaho. (scale 1:100,000). Boise, ID: Joslyn and Morris.
U.S. Department of Labor, Occupational Safety and Health Administration. CFR 29 Part 1926, Subpart P: Safety and Health
Regulations for Construction, Excavations (1986). [Online] Available: <www.osha.gov> (2018).
U.S. Geological Survey (2018). National Water Information System: Web Interface. [Online] Available:
<http://waterdata.usgs.gov/nwis> (2018).
U.S. Geological Survey. (2011). U.S. Seismic Design Maps: Web Interface. [Online] Available:
<https:Hearthquake.usgs.gov/designmaps/us/application.php> (2018).
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APPENDICES
PERM: vapor permeability
PI: Plasticity Index
PID: photoionization detector
PVC: polyvinyl chloride
QC: cone penetrometer value, unconfined compressive strength, psi
QP: Penetrometer value, unconfined compressive strength, tsf
Qu: Unconfined compressive strength, tsf
RMR Rock Mass Rating
RQD Rock Quality Designation
R -Value Resistance Value
SPT: Standard Penetration Test (140:pound hammer falling 30 in. on a 2:in. split spoon)
USCS: Unified Soil Classification System
USDA: United States Department of Agriculture
UST: underground storage tank
V: vane value, ultimate shearing strength, tsf
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Testing & Inspecgon
ACRONYM LIST
AASHTO:
American Association of State Highway and Transportation Officials
ACI
American Concrete Institute
ASCE
American Society of Civil Engineers
ASTM:
American Society for Testing and Materials
bgs:
below ground surface
CBR:
California Bearing Ratio
D:
natural dry unit weight, pcf
ESAL
Equivalent Single Axle Load
GS:
grab sample
IBC:
International Building Code
LL:
Liquid Limit
M:
water content
MSL:
mean sea level
N:
Standard "N" penetration: blows per foot, Standard Penetration Test
NP:
nonplastic
OSHA
Occupational Safety and Health Administration
PCCP:
Portland Cement Concrete Pavement
PERM: vapor permeability
PI: Plasticity Index
PID: photoionization detector
PVC: polyvinyl chloride
QC: cone penetrometer value, unconfined compressive strength, psi
QP: Penetrometer value, unconfined compressive strength, tsf
Qu: Unconfined compressive strength, tsf
RMR Rock Mass Rating
RQD Rock Quality Designation
R -Value Resistance Value
SPT: Standard Penetration Test (140:pound hammer falling 30 in. on a 2:in. split spoon)
USCS: Unified Soil Classification System
USDA: United States Department of Agriculture
UST: underground storage tank
V: vane value, ultimate shearing strength, tsf
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GEOTECHNICAL GENERAL NOTES
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Moisture Content
RELATIVE DENSITY AND CONSISTENCY CLASSIFICATION
Field Test
Coarse -Grained Soils
SPT Blow Counts N Fine -Grained Soils
SPT Blow Counts N)
Very Loose:
< 4 Very Soft:
< 2
Loose:
4-10 Soft:
2-4
Medium Dense:
10-30 Medium Stiff:
4-8
Dense:
30-50 Stiff..
8-15
Very Dense:
>50 Very Stiff:
15-30
MH Inorganic, elastic silts; sandy, gravelly or clayey elastic silts
Hard:
>30
Moisture Content
Description
Field Test
Dry
Absence of moisture, dusty, dry to touch
Moist
Damp but not visible moisture
Wet
Visible free water, usually soil is below
water table
PARTICLE SIZE
Boulders: >12 in. Coarse -Grained Sand: 5 to 0.6 mm Silts: 0.075 to 0.005 mm
Cobbles: 12 to 3 in. Medium -Grained Sand: 0.6 to 0.2 mm Clays: <0.005 mm
Gravel: 3 in. to 5 mm Fine -Grained Sand: 1 0.2 to 0.075 mm
UNIFIED SOIL CLASSIFICATION SYSTEM
Cementation
Description
Field Test
Weakly
Crumbles or breaks with handling or
GW Well -graded gravels; gravel/sand mixtures with little or no fines
slight finger pressure
Moderately
Crumbles or beaks with considerable
Sand & Sandy
Soils
>50%
coarse fraction
passes No.4 sieve
finger pressure
Strongly
Will not crumble or break with finger
Sc Clayey sands; poorly -graded sand/gravel/clay mixtures
pressure
PARTICLE SIZE
Boulders: >12 in. Coarse -Grained Sand: 5 to 0.6 mm Silts: 0.075 to 0.005 mm
Cobbles: 12 to 3 in. Medium -Grained Sand: 0.6 to 0.2 mm Clays: <0.005 mm
Gravel: 3 in. to 5 mm Fine -Grained Sand: 1 0.2 to 0.075 mm
UNIFIED SOIL CLASSIFICATION SYSTEM
Major
Divisions
Symbol Soil Descriptions
Coarse -Grained
Soils
<50%
passes No.200
sieve
Gravel & Gravelly
Soils
<50%coarse fraction
passes No.4 sieve
GW Well -graded gravels; gravel/sand mixtures with little or no fines
GP Poorly -graded gravels; gravel/sand mixtures with little or no fines
GM Silty gravels; poorly -graded gravel/sand/silt mixtures
GC Clayey gravels; poorly -graded gravel/sand/clay mixtures
Sand & Sandy
Soils
>50%
coarse fraction
passes No.4 sieve
SW Well -graded sands; gravelly sands with little or no fines
SP Poorly -graded sands; gravelly sands with little or no fines
SM Silty sands; poorly -graded sand/gravel/silt mixtures
Sc Clayey sands; poorly -graded sand/gravel/clay mixtures
Fine Grained
Soils >50%
passes No.200
sieve
Silts & Clays
LL < 50
ML Inorganic silts; sandy, gravelly or clayey silts
CL Lean clays; inorganic, gravelly, sandy, or silty, low to medium -plasticity clays
OL Organic, low -plasticity clays and silts
Silts & Clays
LL > 50
MH Inorganic, elastic silts; sandy, gravelly or clayey elastic silts
CH Fat clays; high -plasticity, inorganic clays
OH Organic, medium to high -plasticity clays and silts
Highly Organic Soils
PT Peat, humus, hydric soils with high organic content
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GEOTECHNICAL INVESTIGATION TEST PIT LOG
Test Pit Log #: TP -1 Date Advanced: 14 June 2018 Logged by: Maren Tanberg, E.I.T.
Excavated by: Struclartan's Backhoe Service Location: See Site Map Plates
Latitude: 43.6324656 Longitude: -116.3741928
Depth to Water Table: Not Encountered Total Depth: 15.0 Feet bgs
Notes: Piezometer installed to 15.0 feet bgs.
Depth
Field Description and USCS Soil and
Sample
Sample Depth
Qp
Lab
(Feet bgs)
Sediment Classification
Type
(Feet bgs)
Test ID
0.0-2.7
Silt (ML): Brown, dry, very stiff.
2.75-3.0
--Organic content noted to 1.3 feet bgs.
Sandy Silt (ML): Brown, dry, very stiff to
2.7-5.3
hard, with fine to coarse-grained sand.
--Moderate to strong calcium carbonate
cementation noted from 3.6 to 5.3feet bgs.
Poorly Graded Gravel with Sand (GP): Red
brown to light brown, dry, dense to very
5.3-15.0
dense, with fine to coarse-grained sand, fine
to coarse gravel, and 10 -inch -minus cobbles.
--Silt noted from 5.3 to 6.3 feet bgs.
2791 S Victory View Way • Boise, ID 83709 • (208) 376-4748 • Fax (208) 322-6515
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GEOTECHNICAL INVESTIGATION TEST PIT LOG
Test Pit Log #: TP -2 Date Advanced: 14 June 2018
Excavated by: Struckman's Backhoe Service
Latitude: 43.6327012
Depth to Water Table: Not Encountered
Notes: Piezometer installed to 12.0 feet bgs.
26 June 2018
Page # 22 of 29
b180889g_geotech
❑ Special Inspections
Logged by: Maren Tanberg, E.I.T.
Location: See Site Map Plates
Longitude: -116.3719149
Total Depth: 12.0 Feet bgs
Depth
Field Description and USCS Soil and
Sample
Sample Depth
QP
Lab
(Feet bgs)
Sediment Classification
Type
(Feet bgs)
Test ID
Silt with Sand (ML): Brotitm, dry, very stiff,
3.
A
0.0-2.0
with fine-grained sand.
Bulk
1.0-2.0
3..75 75
R -Value
--Organic content noted to 1.2 feet bgs.
Sandy Silt (ML): Bromn, dry, very stiff to
hard, with fine to coarse-grained sand.
2.0-5.3
--Weak calcium carbonate cementation noted
from 2.0 to 4.0 feet bgs.
--Moderate to strong calcium carbonate
cementation noted from 4.0 to 5.3 feet bgs.
Poorly Graded Gravel with Sand (GP): Red
brown to light brown, dry, dense, with fine to
5.3-12.0
coarse-grained sand, fine to coarse gravel,
and 10 -inch -minus cobbles.
--Silt noted from 5.3 to 6.3 feet bgs.
Lab Test ID M LL PI Sieve Analysis (% passing)
% - - #4 #10 #40 #100 #200
A 24.0 37 11 100 99 88 80 73.3
2791 S Victory View Way • Boise, ID 83709 • (208) 376-4748 • Fax (208) 322-6515
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GEOTECHNICAL INVESTIGATION TEST PIT LOG
Test Pit Log #: TP -3 Date Advanced: 14 June 2018 Logged by: Maren Tanberg, E.I.T.
Excavated by: Struckman's Backhoe Service Location: See Site Map Plates
Latitude: 43.6324899 Longitude: -116.3699783
Depth to Water Table: Not Encountered Total Depth: 15.4 Feet bgs
Notes: Piezometer installed to 15.4 feet bgs.
Depth
Field Description and USCS Soil and
Sample
Sample Depth
Qp
Lab
(Feet bgs)
Sediment Classification
Type
(Feet bgs)
Test ID
Lean Clay (CL): Broivn to dark broivn, day,
2'25 _
0.0-1.6
ve stiff
�' ff
2.75
--Organic content noted to 1.8 feet bgs.
Sandy Silt (ML): Brown, dry, stiff to hard,
1.6-4.2
with fine to coarse-grained sand.
--Weak to moderate calcium carbonate
cementation noted throughout.
Poorly Graded Gravel with Sand (GP): Red
brown to light brown, dry, dense to very
4.2-15.4
dense, with fine to coarse-grained sand, fine
to coarse gravel, and 12 -inch -minus cobbles.
--Pocket of silt noted from 5.0 to 5.5 feet bgs.
2791 S Victory View Way • Boise, ID 83709 • (208) 376-4748 • Fax (208) 322-6515
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26 June 2018
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b180889g_geotech
❑ Special Inspections
GEOTECHNICAL INVESTIGATION TEST PIT LOG
Test Pit Log #: TP -4 Date Advanced: 14 June 2018 Logged by: Maren Tanberg, E.I.T.
Excavated by: Strucicman's Backhoe Service Location: See Site Map Plates
Latitude: 43.6333200 Longitude: -116.3734746
Depth to Water Table: Not Encountered Total Depth: 12.4 Feet bgs
Notes: Piezometer installed to 12.4 feet bgs.
Depth
Field Description and USCS Soil and
Sample
Sample Depth
Qp
Lab
(Feet bgs
Sediment Classification
Type
(Feet bgs)
Test ID
Silt (ML): Brovnn, dry, very stiff.
2.25-
0.0-3.0
--Organic content noted to 1.0 foot bgs.
3.75
Sandy Silt (ML): Brovim, dry, stiff to hard,
with fine to coarse-grained sand.
3.0-8.8
--Moderate to strong calcium carbonate
cementation noted from 4.0 to 6.2 feet bgs.
--Induration with manganese staining noted
firom 6.2 to 7.3feet bgs.
Poorly Graded Gravel with Sand (GP): Red
brown to light brown, dry, dense to very
8.8-12.4
dense, with fine to coarse-grained sand, fine
to coarse gravel, and 10 -inch -minus cobbles.
--Silt content noted om 8.8 to 10.0 eet bgs.
2791 S Victory View Way • Boise, ID 83709 • (208) 376-4748 • Fax (208) 322-6515
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MATERIALS
TESTING 6
INSPECTION
26 June 2018
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❑ Environmental Services ❑ Geotechnical Engineering ❑ Construction Materials Testing ❑ Special Inspections
GEOTECHNICAL INVESTIGATION TEST PIT LOG
Test Pit Log #: TP -5 Date Advanced: 14 June 2018 Logged by: Maren Tanberg, E.I.T.
Excavated by: Struckman's Backhoe Service Location: See Site Map Plates
Latitude: 43.6331919 Longitude: -116.3709822
Depth to Water Table: Not Encountered Total Depth: 15.0 Feet bgs
Notes: Piezometer installed to 15.0 feet bgs.
2791 S Victory View Way • Boise, ID 83709 • (208) 376-4748 • Fax (208) 322-6515
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Testing & Inspection
Field Description and USCS Soil and
Sample
Sample Depth
QpTest
Lab
Sediment Classification
Tye
(Feet bgs)
ID
Lean Clay (CL): Broivn, dry, very stiff to
2 75 -
hard.
4.5+
--Organic content noted to 2.5feet bgs.
Sandy Silt (ML): Bromm, diy, very stiff to
rO5
hard, ivithfine to coarse-grained sand
--Moderate to strong calcium carbonate
cementation noted from 4.0 to 5.0feet b s.
Poorly Graded Gravel with Sand (GP):
Bromn, dry, dense to very dense, Wth fine to
coarse-grained sand, fine to coarse gravel,
and 10 -inch -minus cobbles.
2791 S Victory View Way • Boise, ID 83709 • (208) 376-4748 • Fax (208) 322-6515
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MATERIALS
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26 June 2018
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b180889g_geotech
❑ Environmental Services ❑ Geotechnical Engineering ❑ Construction Materials Testing ❑ Special Inspections
GRAVEL EQUIVALENT METHOD — PAVEMENT THICKNESS DESIGN PROCEDURES
Pavement Section Design Location: Verado West Subdivision, Resiential Roadway
Average Daily Traffic Count:
500 All Lanes & Both Directions
Design Life:
20 Years
Traffic Index:
6.00
Climate Tactor:
1 R -Value of Subgrade: 5.00
Subgrade CBR Value:
3 Subgrade Mr: 4,500
R -Value of Aggregate Base:
80
R -Value of Granular Borrow:
60
Subgrade R -Value:
5
Expansion Pressure of Subgrade:
1.41
Unit Weight of Base Materials:
130
Total Design Life 18 kip ESAL's:
33,131
ASPHALTIC CONCRETE:
Gravel Equivalent, Calculated:
0.384
Thickness:
0.1969231 Use= 2.5 Inches
Gravel Equivalent, ACTUAL:
0.41
CRUSHED AGGREGATEBASE:
1.95
Gravel Equivalent (Ballast):
0.768
Thickness:
0.329Use= 4 Inches
Gravel Equivalent, ACTUAL:
0.773
SUBBASE:
4.00
Gravel Equivalent (Ballast):
1.824
Thickness:
1.051 Use = 14 Inches
Gravel Equivalent, ACTUAL:
1.940
TOTAL Thickness: 1.708
Thickness Required by Exp. Pressure: 1.562
2791 S Victory View Way • Boise, ID 83709 • (208) 376-4748 • Fax (208) 322-6515
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Testing pection
Design
Depth
Substitution
Inches
Ratios
Asphaltic Concrete (at least 2.5):
2.50
1.95
Asphalt Treated Base (at least 4.2):
0.00
Cement Treated Base (at least 4.2):
0.00
Crushed Aggregate Base (at least 4.2):
4.00
1.10
Subbase (at least 4.2):
14.00
1.00
2791 S Victory View Way • Boise, ID 83709 • (208) 376-4748 • Fax (208) 322-6515
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INSPECTIO
26 June 2018
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❑ Environmental Services ❑ Geotechnical Engineering ❑ Construction Materials Testing ❑ Special Inspections
R -VALUE TEST DATA
Source and Description:
TP -2: 1.0'-2.0', Silt with Sand
Date Obtained:
15 June 2018
Sample ID:
18-7542
Sampling and
Pre aration:
ASTM D75:
Moisture Content (%)
AASHTO T2:
X
ASTM
D421:
Expansion Pressure (psi)
AASHTO
T87:
X
Test Standard:
ASTM
D2844:
382
AASHTO
T190:
84
Idaho T8:
X
5.
Sample
A
B
C
Dry Density (lb/ft)
91.8
88.5
87.4
Moisture Content (%)
24.7
26.4
27.6
Expansion Pressure (psi)
1.74
1.41
0.15
Exudation Pressure (psi)
382
197
84
R -Value
6
5.
4
R -Value @ 200 psi Exudation Pressure = 5
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2791 S Victory View Way • Boise, ID 83709 - (208) 376-4748 • Fax (208) 322-6515
www.mti-id.com • mti(atimti-id.com Copyrig 8 Materials
Testing
8lnspectian
Vicinity Map
Plate 1
MAP NOTES:
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Drawing: B180889g
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MATERIALS
TESTING &
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INSPECTION
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2791 S. Victory View Way Phone: 208 376-0749
Boise, ID 83709-2835 Fax: 208 322.6515
E-mail: m8�m0-id.com
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Site Map
Plate 2
NOTES:
I
• Not to Scale
L
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W
RESIDENTIALAREA
W
LEGEND
Approximate Site —
W
I
Boundary
Approximate MTI Test
— — —
— — —
— — — — —
— — USTICK ROAD — — — — — —
— — — — — — — — — — — — — —
Pit Location
wilh Piezometer
South Slough
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RESIDENTIAL AREA
Drawn by: WIT
14 June 2018
•
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Drawing: 3180889g
MATERIALS
I
�..—..—..—..—..—..—..—.
TESTING&
INSPECTION
2791 S. Victory View Way Phone: 208376-0748
Bose, ID 83709-2835 Fax: 208 322-6515
Email: m%ml-Ko m