Geotech ReportSITE
TING. 11 G. ILILC
Mr. Shawn Brownlee
Trilogy Development
2358 South Titanium Place
Meridian, Idaho 83642
Re: Geotechnical Report
Jump Creek/ Jump Creek Subdivision
North Blackcat Road
Meridian, Idaho
Dear Shawn:
June 5, 2014
Page 1 of 29
14046GI001
As per your authorization, on May 20, 2014 this engineer observed the advancement of three
hand auger borings on the property due south of your MDC property on the west side of
Blackcat Road in Meridian, Idaho. The purpose of this investigation was to confirm that the
previous recommendations provided for the Jump Creek Subdivision also apply to this
additional parcel. It is our understanding that the parcels will be developed together and is
now referred to as Jump Creek Subdivision.
Based on the observed conditions, the property is acceptable from a geotechnical perspective
for development as a residential subdivision and our prior recommendations for MDC Property
are appropriate forJump Creek Subdivision. This report has been modified to include the
additional exploration and changes all references to MDC to Jump Creek.
Recommendations for foundation construction, earthwork, and pavement design and storm
water disposal are included herein. We appreciate this opportunity to be of service. Should
you have any questions or require additional information, please contact our office at your
convenience.
Respectfully submitted;
Bob J. Arnold, PE
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Tli
TABLE OF CONTENTS
ILILC
INTRODUCTION............................................................................................................ 3
Purposeand Scope.................................................................................................... 3
Authorization............................................................................................................ 4
Warrantyand Limitations.........................................................................................4
RESEARCH & BACKGROUND......................................................................................... 5
General...................................................................................................................... 5
VicinityMap.............................................................................................................. 5
FieldInvestigation..................................................................................................... 6
ObservedConditions................................................................................................. 6
DESIGN & CONSTRUCTION RECOMMENDATIONS
......................................................... 8
GeneralEarthwork....................................................................................................
8
Inspection& Testing.................................................................................................
9
Excavations................................................................................................................
9
PavementSection.....................................................................................................
10
FoundationSystem...................................................................................................
10
Slabon Grade Concrete............................................................................................
11
StormWater..............................................................................................................
12
UndergroundUtilities...............................................................................................12
Contractor Inspections..............................................................................................
13
GeneralComments...................................................................................................
13
APPENDIX...............................................................
......................................14
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;lflING, ILILC
Geotechnical Report
Jump Creek Subdivision
North Blackcat Road - Meridian, Idaho
INTRODUCTION
Purpose and Scope
This report presents the results of a geotechnical investigation & resulting recommendations
for a residential subdivision to be constructed on a parcel located on the northwest corner of
Blackcat Road & McMillan Road Meridian, Idaho. This assessment was performed on Ada
County Parcels #50428410000, # 50428449800, & #SO423449010. Ada County Assessor website
indicated the parcels include approximately 80 acres and have been assigned street addresses
4940 W. McMillan Road & 5335 N. Blackcat Road, Meridian, Idaho.
The purpose of this investigation was to evaluate the subsurface soil conditions and provide
recommendations for building residential structures and civil construction. The field
investigation included subsurface exploration by means of a rubber tire mounted backhoe and
hand auger. Soil samples were gathered and test pit & boring logs generated by our project
engineer. Selected soil samples were submitted to soil laboratories for testing. After the field
investigation and laboratory testing was completed, all available field and laboratory test data
was reviewed, the assumed design information was evaluated, and this report was prepared.
This report summarizes our findings, conclusions, and recommendations regarding the
geotechnical aspects of the project.
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Authorization
ILLC
E-mail authorization to proceed with the original MCD geotechnical investigation was received
from Mr. Shawn Brownlee on July 17, 2013. The Bews or southern two parcels were added to
this project in March 2014. Authorization to proceed and the use of the recommendations
provided herein indicate the client's and their design team's acceptance of the scope of work,
warranty, limitations and general conditions provided herein and within the submitted and
approved proposal.
Warranty and Limitations
The exploration and evaluation of subsurface conditions documented herein is considered
sufficient to form a basis for the provided recommendations. The provided recommendations
are based on the available soil information and preliminary design details either assumed or
furnished by the client. It is warranted that these recommendations have been promulgated
after being prepared in accordance with locally accepted professional engineering and
geotechnical engineering practice. No other warranties are implied or expressed.
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RESEARCH & BACKGROUND
General
Asper your request, on July 29, 2013, this engineer observed the excavation of six test pits on
MCD parcel located at 5335 North Blackcat Road, in Meridian, Idaho. On May 28, 2014 three
hand augured borings were advanced on the southern or Bews property at 4940 West
McMillan Road. At the time of exploration, the southern quarter of the MCD property was
planted in corn that was irrigated in furrows flowing from east to west. The northern 3/4 of the
property was a historical tree farm with many trees still present. The tree farm area was also
farmland prior to 2004. Along Blackcat Road, a small parcel, approximately 150' x 200',
includes a building used as a maintenance facility for farm equipment. The larger ofthe two
Bews parcels was also planted at the time of our field investigation. This led to hand auger
borings being located in the non farmed 2.6 acres parcel along McMillan Road and along the
field access roads.
At the time of this investigation, the surface was firm and stable but large holes are present in
the tree farm area where trees have previously been harvested. These holes are hidden in
surface weeds and grasses requiring a spotter to access this area with trucks and the backhoe.
Vicinity Map
Prior to our field investigations, a proposed development plan was provided by Bailey
Engineering and an aerial photo was obtained from Google Earth. This photo was used in the
field with a hand held GPS unit to plot the approximate locations of the test pits. This photo
has been included in the appendix.
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Field Investigation
Six Test pits and three hand auger borings were advanced at the selected locations to explore
subsurface conditions and evaluate their consistency. The test pits were excavated with a tire -
mounted, backhoe equipped with twenty-four inch bucket. R. P. Jones Drilling of Boise, Idaho
supplied the backhoe and operator. Hand auger borings were advanced by our staff engineer
and a soils technician. Our engineer gathered representative samples from the test pit spoil
piles and from the hand auger during excavation. The samples were field classified, labeled
according to test pit number and depth, bagged in plastic storage bags, and transported to the
laboratory for additional testing. Sieve analysis (ASTM Test Method C136-93), Moisture
Content (ASTM Test Method 2216-92) and Liquid Limit, Plastic Limit and Plasticity Index (ASTM
Test Method D 4318-93) testing were performed on selected samples. A near surface sample
was selected and forwarded to a specialty soils laboratory for R -Value testing, (Idaho Method T-
8). Tests were performed in general accordance with the cited ASTM and ITD test methods.
Observed Conditions
Test Pits TP -1 and TP -2 were located adjacent to a field access road alongthe south end of the
property. Test pits TP -3 to TP -6 were located within the tree farm area. Borings HA -1 to HA -3
were advanced along the edges of the southern field where access could be gained without
disrupting irrigation. All test pits and borings were backfilled after sampling was completed.
Piezometers were installed in the borings to allow for future groundwater measurements.
It is assumed that the root zone in the corn and grain field is as deep as the furrows /
corrugates or approximately six inches. Grasses and weeds within the tree farm have a similar
root depth. The trees can be expected to have roots up to 2.0-2.5 feet deep. It is unknown if a
buried irrigation system is present within the tree farm. The client has reported that the tree
farm was historically flood irrigated.
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ILTIING„ ILLC
At the time of excavation, groundwater was observed entering the test pits at between 6.0 and
7.0 feet below the existing ground surface. In each test pit the groundwater rose
approximately one foot prior to the test pit being backfilled. The surface soil varied from 3.5 to
5.5 feet deep in the six test pits. It appears that groundwater may have historically risen as high
as the bottom of the surface (silt / clay) soil layer. It is noted that groundwater in the western
most monitoring wells at the Bridgetower project, directly across Blackcat Road from the onsite
building, was measured at 2.0 feet below the surface in October 2011. Groundwater in the
next two nearest wells at Bridgetower was measured at 4.0 feet below the ground surface.
These wells are shown on the aerial photo in the appendix. Hand auger borings were advanced
as deep as possible on the southern parcels. All three borings were terminated when large
gravel was encountered and auguring was blocked. It is noted that the northeast monitoring
well was destroyed shortly after installation. The west well was also ran over and filled with soil
to 4.5' below adjacent grade. Newwells will be installed at these locations.
The surface soils consist mostly of lean clay or elastic silt or sandy silts. The clay soils observed
were typically less than two feet thick and therefore will be completely penetrated by road
construction. Below the surface layer, the upper 3.5 —5.5 feet is a low plasticity or elastic silt.
In test pits TP -1, TP -2 and TP -6 and in borings HA -1, HA -2 & HA -3 a thin cemented layer was
encountered below the surface soils. This layer is identified as hardpan on the test pit logs but
was very weakly cemented and easily excavated / augured. Gravels were contacted at 4.5 to 5.5
feet in all locations. The top of the sand and gravel is very silty. Free draining materials were
encountered in the bottom of each test pit. The average depth to free draining materials is
approximately 6.5 to 7.0 feet. At this depth gravels are too large to hand auger.
On June 6, 2014 the southernmost monitoring well, HA -1 was measured to be 6.8 feet deep
and dry. HA -2 & HA -3 were dry when installed on May 20, 2014 to 6.0' and 6.5' feet respectfully
but have since been destroyed.
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DESIGN & CONSTRUCTION RECOMMENDATIONS
General Earthwork
All soils encountered on the property are acceptable for filling of residential lots. Therefore,
materials removed from the street sections and subsurface stormwater storage areas can be
utilized as structural fill. The only exception is the surface soil that contains excessive organic
materials. Removal of the majority of the organic materials will require grubbing of
approximately four to six inches of surface soils. Deeper excavation may be required in the tree
farm and areas along the property boundaries where small trees and bushes are present. The
depth of grubbing is to be adjusted in the field to ensure that organic materials are properly
removed from beneath future pavements and structural fills.
If used for fill, the surface soils will require moisture contents within two percent of optimum
for effective compaction. These soils will easily become too wet or too dry for effective
compaction. These soils can be expected to perform poorly if wet and subjected to rubber tired
equipment. If construction is to occur during wet weather or wet surface soil conditions, low-
pressure, tracked mounted construction equipment is recommended. Rutting caused bythe
contactor using rubber -tired equipment on a wet subgrade can be expected and should be
repaired at contractor expense. This information is to be supplied to earthwork contractors
prior to construction.
Structural fills less than three feet deep are to be compacted to 95 % of the maximum dry
density by ASTM D698, Standard Proctor. For deeper fills, and fill intended to contain irrigation
canals or storm water runoff, all fill material and the subgrade surface are to be compacted to
95 % of the maximum dry density as determined by ASTM D1557, Modified Proctor. Structural
fill is to extend laterally outside foundations a distance equal to the depth of structural fill.
208-440-6276 biarnoldpe@msn.com (8) Post Office Box 190537 Boise, Idaho 83719
Structural fill should be placed in uniform, thin horizontal lifts, moisture conditioned as
necessary, and compacted to the above requirements. Compaction of fine grained soils will
greatly reduce the infiltration rate for surface water, effectively sealing the ground surface and
crawlspace floors to percolation.
Inspection & Testing
A qualified engineer or his representative should monitor fill placement to ensure the work is
performed in accordance with these recommendations. Testing should be performed in
accordance with ASTM Test Methods D3017-88 and D2922-91 (nuclear densometer). Field
nuclear moisture - density testing shall be performed on each lift of compacted fill for every
10000 square feet of surface area or one test per lot, whichever is greater. It is noted that
structural fill can pass compaction tests and still be unacceptable if pumping, rutting or
deflecting under vehicle or foot traffic.
Excavations
Shallow excavations and trenches that do not exceed four feet in depth may be constructed
with side slopes approaching vertical. Below this depth it is recommended that slopes not
exceed a vertical to horizontal ratio of one to one. The ability of the materials on site to
maintain a vertical or near vertical excavation when standing open without support over any
extended period of time can be expected to be quite variable. This information is provided for
planning purposes. It is our opinion that maintaining safe working conditions is the
responsibility of the contractor. Jobsite conditions such as soil moisture content, weather
condition, earth movements and equipment type and operation can all affect slope stability. All
excavations should be sloped or braced as required by applicable local, state and federal
requirements.
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Pavement Section
A pavement section has been calculated based upon a laboratory generated R -Value of R=8 and
Traffic Indexes of TI=6 & TI=8. Calculation sheets are included in the appendix. Based upon this
data the following pavement sections are recommended.
Material
Layer
Residential Street
T1=6
Collector Street
TI=8
Asphaltic Concrete
2.5"3.0"
Base Coarse (%" minus)
4.0"
4.0"
Sub base (Pitrun)
12.0"
17.0"
It is noted, that it is common forthe local jurisdiction to require a standard design or to match
existing pavement section when working on collector or arterials. Therefore the local highway
district / street department should be consulted concerning construction within the Blackcat
Road right of way. Materials meeting the requirements of ISPWC orACHD will be required for
any work within this project.
Foundation System
The proposed single family residences may be supported on conventional, continuous and
isolated pad foundations founded upon the native soils or upon structural fill extending to
these native soils. Based upon proper placement and compaction of structural fill, bearing
pressures of up to 1500 psf are allowed. A one-third increase in allowable bearing capacity is
permitted when transient loads such as wind or seismic are included. Either crawlspaces or slab
on grade floors are acceptable.
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MUTING, LUC
Slab on Grade Concrete
Care must be taken so that all excavations below concrete floors and slabs are properly
backfilled in accordance with the structural fill recommendations outlined herein. This is very
critical where a slab will extend over utility trenches or retaining wall backfill. Trenches and
wall backfill areas are to be filled in lifts and benched each lift so that fill is not placed against a
vertical soil face greater than three feet tall. Testing is to confirm that compaction has been
achieved. Areas of excessive yielding should be excavated and backfilled with structural fill.
Slab on grade floors, sidewalks and pavements should be placed atop a minimum of 0.5 feet of
granular structural fill materials. Any additional fill used to increase the elevation of slab on
grade concrete should meet the requirement for structural fill. After construction of the
building pad, a six inch granular mat should be provided below the floor slabs. The mat should
consist of sand or sand -gravel mixture with non -plastic fines. The material should all pass a
3/4 inch sieve and should contain less than seven percent passing the # 200 sieve. The mat
shall be compacted to the requirement for structural fill. All slabs should be suitably reinforced
to make them as rigid as possible. Proper joints should be provided at the junctions of the slab
and foundation system so that independent movement can occur without causing damage.
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Storm Water
It is recommended that storm runoff be directed away from all open excavations and not be
allowed to puddle on subgrade soils. Due to the present of shallow groundwater, disposal of
groundwater in surface detention or retention ponds or constructed lakes or ponds is
recommended. If water is to percolate through the surface soils (including the cemented soil
layer) a percolation rate of P= 1.0 inch/hour is recommended for design. If drainage facilities
are extended to free draining materials (and backfilled if needed with free draining pitrun) a
percolation rate of P = 6 inch/hour is to be used for design. Extension to free draining
conditions is to be confirmed at the time of construction.
This consultant provided consulting services on Phase II of Oak Creek Subdivision, located to the
south across McMillan Road. This development includes standard infiltration trenches with 4.5'
of drain rock and 3.0' of filter sand.
Underground Utilities
Test pits revealed that deep utilities trenches may require dewatering. It is not anticipated that
large backhoes will experience any difficulties excavating the onsite materials. No bedrock
formation was encountered on the subject property. Sloughing of trenches can be expected
when working below the groundwater surface.
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IL'lf'ING. ILILC
Contractor Inspections
This report has been prepared with the intent to provide specific design information to the
developer and the civil engineering consultant. It is not intended to act as any contractors "Due
Diligence" or subsurface inspection prior to estimating construction costs or actual
construction. Contractors that estimate material quantities, material depths, or the volume
and depth to groundwater based solely upon this report do so at their own risk. It is
recommended that such values be confirmed as close as possible to the time / date of
construction at specific locations as detailed in design plans.
General Comments
After the plans and specifications for construction are completed, it is recommended that this
consultant be provided the opportunity to review the final design and specifications. This
review will confirm that the earthwork recommendations have been properly interpreted and
implemented. At that time, it may be necessary to submit supplementary recommendations.
This review is a part of this service and will not result in additional invoicing unless additional
research and recommendations are needed.
Testing and inspection services are recommended herein. Proper quality control during
construction is required to confirm materials and methods and thereby obtain a desirable
finished product. Monitoring and testing should also be performed to verify suitability of
materials used for structural fills and to confirm subgrade grubbing, stability, and proper
placement and compaction of fills. Any deviations from the herein described subsurface
conditions should be brought to the attention of this consultant.
This report has been prepared for the exclusive use of the identified client and their retained
design consultants. Findings and recommendations within this report are for specific
application to the proposed construction described herein and apply only to the property
identified.
Appendix Follows
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TING. ILLC
APPENDIX
Aerial Photo with Test Pit/Boring Locations
Test Pit Logs (5)
Hand Auger Boring Logs (3)
Pavement Section Calc Sheets (2)
R -Value
Soil Log Legend
Abbreviations & Acronyms
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LL
iF, I -
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Test Pit Log
Test Pit #:
TP -1
Client:
Trilogy Development
Project:
Jump Creek Subdivision
Location:
SW Corner
ILILC
File: 14046G1001
Date Excavated: 07/29/13
Excavated By: Tire mounted Backhoe
Logged By: Bob Arnold
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Sample
0
q
q
DEPTH
SOILS DESCRIPTION
Type
4
4
10
40
200
M
PI
LL
0.0
Moist, Brown, Silt
2.0
2.0
Wet, Brown, Sandy, SILT (ML)
Bag
99
93
54.7
22.9
NP
NP
2.5
3.5
3.5
Hardpan, (very weakly cemented silt
-
and sandy silt)
5.5
5.5
Gravel Contact
5.5
Saturated, Silty, Sand & Gravel
8.0
Notes
Terminated due to sloughing
Groundwater entering Test Pit @ 6.0'
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Test Pit #:
Client:
SITE
IL
Test Pit Log
TP -2
Trilogy Development
Project: Jump Creek Subdivision
Location: Center South End
ILILG
File: 14046131001
Date Excavated: 07/29/13
Excavated By: Tire mounted Backhoe
Logged By: Bob Arnold
208-440-6276 * blarnoldpe@msn.com (17) Post Office Box 190537 * Boise, Idaho 83719
sample
#
#
#
#
DEPTH
SOILS DESCRIPTION
Type
4
10
40
2110
M
PI
LL
0.0
Moist, Brown, Silt
2.0
2.0
Moist, Brown, Elastic, Silt
Bkt
100
99
98
92.4
21.7
3.2
26.5
2.5
4.5
R-Value—R=8
4.5
Hardpan
5.0
5.0
Gravel Contact
5.0
Saturated, Brown, CLAYEY,
Bag
94
89
74
58.6
14.9
11.3
29.6
-
Sand &Gravel
5.0
10.0
(Fines classify as CL)
Notes
Terminated due to sloughing
Groundwater entering Test Pit @ 6.0'
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N1V,SUILT11
Test Pit Log
Test Pit #: TP -3
Client: Trilogy Development
Project: Jump Creek Subdivision
Location: Center, W Side,
North of Tree Farm
ILILC
File: 14046GIO01
Date Excavated: 07/29/13
Excavated By: Tire mounted Backhoe
Logged By: Bob Arnold
208-440-6276 * b)arnoldpe@msn.com (18) Post Office Box 190537 * Boise, Idaho 83719
Sample
#
#
#
#
DEPTH
SOILS DESCRIPTION
Type
4
10
40
100
M
PI
LL
0.0
Dry, Brown, CLAY (CL)
Bag
98
95
89
77.0
11.6
8.4
29.3
2.0
2.5
2.5
Moist, Brown, Silt
-
(wetter with depth)
4.5
4.5
Gravel Contact
4.5
Saturated, Silty, Sand & Gravel
8.0
Notes
Terminated due to sloughing
Groundwater entering Test Pit at 6.5'
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Test Pit Log
Test Pit #:
TP -4
Client:
Trilogy Development
Project:
Jump Creek Subdivision
Location:
Center of Site
LLC
File: 14046GIO01
Date Excavated: 07/29/13
Excavated By: Tire mounted Backhoe
Logged By: Bob Arnold
208-440-6276 * bjarnoldpe@msn.com (19) Post Office Box 190537 * Boise, Idaho 83719
Sample
4
8
M
#
DEPTH
SOILS DESCRIPTION
Type
4
10
40
209
M
PI
LL
0.0
Dry, Brown, SILT (ML)
Bag
190
97
88
82A
18.5
5.6
28.5
1.0
1.5
1.5
Moist, Light Brown, Silt
3.0
3.0
Wet, Dark Brown, SILT (ML)
Bag
199
82
77
68.8
17.5
5.6
29.1
4.0
5.0
5.0
Contact with Silty Gravel
5.0
Saturated, Silty Sand and Gravel
10.0
Notes
Terminated due to sloughing
Groundwater entering Test Pit at 7.0'
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Test Pit Log
Test Pit #:
TP -5
Client:
Trilogy Development
Project:
Jump Creek Subdivision
Location:
Center north end
File: 14046GI001
Date Excavated: 07/29/13
Excavated By: Tire mounted Backhoe
Logged By: Bob Arnold
208-440-6276 * biarnoldpe@msn.com (20) Post Office Box 190537 • Boise, Idaho 83719
Sample
7#
#1
p
#
DEPTH
SOILS DESCRIPTION
Type
4
10
40
200
M
PI
LL
0.0
Dry, Light Brown, Silt
2.0
2.0
Moist, Dark Brown, SILT (ML)
Bag
100
95
85
69.9
16.6
5.6
27.9
-
4.0
5.0
5.0
Hardpan
S.5
5.5
Gravel Contact
5.5
Saturated, Silty Sand and Gravel
8.0
Notes
Terminated due to sloughing
Groundwater entering Test Pit at 7.0'
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ILTIIN,.ILLC
Test Pit Log
Test Pit #:
TP -6
Client:
Trilogy Development
Project:
Jump Creek subdivision
Location:
Northwest Corner
File: 14046GIO01
Date Excavated: 07/29/13
Excavated By: Tire mounted Backhoe
Logged By: Bob Arnold
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Sample
0
R
IL
p
DEPTH
SOILS DESCRIPTION
Type
4
10
401
00M
PI
LL
0.0
Dry, Brown, Silt
2.0
2.0
Moist, Dark Brown, SILT (ML)
Bag
100
99
97
85.5
19.7
3.2
26.8
3.0
4.0
4.0
Moist, Brown, Elastic Silt
5.0
5.5
Gravel Contact
5.5
Saturated, Silty Sand and Gravel
8.0
Notes
Terminated due to sloughing
Groundwater entering Test Pit at 7.0'
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IE
I
Hand Auger Log
Test Pit #: Hand Auger -1
Client: Trilogy
Project: Jump Creek Subdivision
Location: South end of Bews
IULC
File #:
14001GIO01
Date Excavated:
5/20/14
Excavated By:
Hand Tools
Logged By:
KA/BA
DEPTH
SOUS DESC8IPTION
Sample
Type
#
4
#
10
#
40
4
200
M
PI
LL
0.0
Dry, Brown, CLAY (CL)
Bag
100
99
96
84.2
19.8
11.0
31.8
-
(No rootzone present in access road)
3.0
3.0
Brown, Moist, SILT (ML)
Bag
97
76
49
29.6
27.7
NP
NP
4.5
4.5
Hardpan, weakly cemented silt
5.0
5.0
Gravel Contact, weakly cemented at top
-
Grades cleaner with depth.
7.0
Too big to auger at 7.0'
7.0
Bottom of Boring—Auger Refusal
Piezometer installed
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IE
Hand Auger Log
Test Pit#: Hand Auger -2
Client: Trilogy
Project: Jump Creek Subdivision
Location: West Center of Bews
ILIL-C
File #:
Date Excavated:
Excavated By:
Logged By:
14001GI001
5/20/14
Hand Tools
KA/BA
208-440-6276 * blarnoldpe@msn.com (23) Post Office Box 190537 * Boise, Idaho 83719
Sample
q
qq
q
DEPTH
SOILS DESCRIPTION
Type
4
10
40
200
M
PI
LL
0.0
Dry, Brown, CLAY (CL)
Bag
100
99
94
82.5
26.2
14.2
35.9
-
(No rootzone present in access road)
2.5
2.5
Brown, Moist, SILT
Bag
4.0
4.0
Hardpan
4.5
4.5
Gravel Contact, weakly cemented at top
-
Grades cleaner with depth.
6.0
Too big to auger at 6.0'
6.0
Bottom of Boring—Auger Refusal
Piezometer installed
208-440-6276 * blarnoldpe@msn.com (23) Post Office Box 190537 * Boise, Idaho 83719
SITE
.TING. LUC
Hand Auger Log
Test Pit M.
Hand Auger — 3
Client:
Trilogy
Project:
Jump Creek Subdivision
Location:
NE Corner of Bews
File #:
14001GIO01
Date Excavated:
5/20/14
Excavated By:
Hand Tools
Logged By:
KA/BA
208-440-6276 * biarnoldpe@msn.com (24) Post Office Box 190537 * Boise, Idaho 83719
Sample
#
#
#
#
DEPTH
SOILS DESCRIPTION
Type
4
10
40
200
M
PI
LL
0.0
Dry, Brown, CLAY
-
(No rootzone present in access road)
Bag
2.5
2.5
Brown, Moist, SILT
Bag
4.5
4.5
Hardpan
5.0
5.5
Gravel Contact, weakly cemented at top
-
Grades cleaner with depth.
6.5
Too big to auger at 6.5'
6.5
Bottom of Boring — Auger Refusal
Piezometer installed
208-440-6276 * biarnoldpe@msn.com (24) Post Office Box 190537 * Boise, Idaho 83719
SITE
ILlfllNG. ILILC
DESIGN SECTION CALCULATIONS
(ACHD R -Value Method)
Project: Jump Creek Subdivision File No-- 14046
Blackcat Road Calc BY: B. Arnold
Client: Trilogy Development Date_ 06/01/13
Design Thickness Equation:
T = 0.0032 (TI) (100-11)(12) = GE (inches)
T= Design Thickness TI = Traffic Index = 6 (By ACHD)
GE = Gravel Equivalent R = R -Value = 8 (By Test)
GE= 21.7 Inches
ACHD ACP. 3/4" Road Base and Aggregate Subbase
Actual Thickness Equivalent Thickness
ACHD Asphalt Concrete Thickness = 2.5 Inches ACE= 5.0 Inches
3/4" Road Base Thickness Desired= 4.0 Inches RBE= 4.4 Inches
Calculated Aggregate Subbase Thickness Equation:
Subbase Thickness=SB=GE-ACE-RBE
SB= 12.3 Inches
CALCULATED DESIGN SECTION
ACHD Asphaltic Concrete= 2.5 inches
3/4" Road Base = 4.0 inches
Aggregate Subbase = 13.0 inches
RECOMMENDED DESIGN SECTION
Asphaltic Concrete = 2.5 inches
3/4" Road Base = 4.0 inches
Aggregate Subbase = 13.0 inches
208-440-6276 * bjarnoldpe@msn.com (25) Post office Box 190537 * Boise, Idaho 83719
TING, ILILIC
DESIGN SECTION CALCULATIONS
(ACHD R -Value Method)
Project: Jump Creek Subdivision File No.: 14046
Blackcat Road Calc By: B. Arnold
Client: Trilogy Development Date: 08/01/13
Design Thickness Equation:
T = 0.0032 (TI) (100-R)(12) = GE (inches)
T= Design Thickness TI = Traffic Index = 8 (By ACHD)
GE = Gravel Equivalent R = R -Value = 8 (By Test)
GE= 28.8 Inches
ACHD ACP. 3/4" Road Base and Aggregate Subbase
Actual Thickness Equivalent Thickness
ACHD Asphalt Concrete Thickness = 3.0 Inches ACE= 7.5 Inches
3/4" Road Base Thickness Desired = 4.0 Inches RBE= 4.4 Inches
Calculated Aggregate Subbase Thickness Equation:
Subbase Thickness=SB=GE-ACE-RBE
SB= 16.9 Inches
CALCULATED DESIGN SECTION
ACHD Asphaltic Concrete= 3.0 inches
3/4" Road Base = 4.0 inches
Aggregate Subbase = 17.0 inches
RECOMMENDED DESIGN SECTION
Asphaltic Concrete = 3.0 inches
3/4" Road Base = 4.0 inches
Aggregate Subbase = 17.0 inches
208-440-6276 * bjarnoldpe@msn.com (26) Post Office Box 190537 * Boise, Idaho 83719
ITE
WILTING. ILIUC
R -Value
(By MTI of Boise, Idaho)
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208-440-6276 * bjarnoldpe@msn.com (27) Post Office Box 190537 * Boise, Idaho 83719
SATE
TING ILLC
Soil Log Legend
UNIFIED SOIL CLASSIFICATION SYSTEM
(ASTM STANDARD TEST METHOD D 2487 FOR CLASSIFICATION OF SDII MR FNr,IMFFRIMr. RI IRRn<ccl
MAIOa
DNISIONS
TYPESICAL
DCRIPiIONs
COARSE
GRAVEL &
<5%-#500
GW
Well -graded gravel, gravel -sand mixture, little or no fines.
GRAINED
GRAVELLY
SOILS
SOILS
<50%-#500
<50%-#4
GP
Poorly -graded gravel, gravel sand m -adore, little or na fines
5-12%x{500
>12%-#500
GM
GC
Silty gravel,gravel-sandiil[miMuras
Clayey gravel, gravel -sand -clay mixtures
SAND &SANDY
<5%-#500
SW
Well -graded sand, gravelly sand, little or no fines.
50115
>50%-#4
SP
Poorly -graded sand, gravelly sand, little or no fines
>72%-#500
SM
Silty sand, sand -silt mixtures
SC
Clayey sand, sand -clay mixtures
FINE
GRAINED
SOILS
SILTS AND CLAYS
LL<50%
INORGANIC
ML
Inorganic silt and very fine sand, rock flour, silty or clayey
fine sand or clayey silt with slight plasticity
>50%-#500
ORGANIC
L
"11
OL
Lean clay -low to medium plasticity, gravelly clay, sandy
clay, silty clay
Organic silt and organicsilty, clay of low plasticity
SILTS AND CLAYS
INORGANIC
MH
Elastic silt, micaceous ordiatomeceous fine sand or silty
LL> 50%
soil.
[H
Fat clay -high plasticity
ORGANIC
OH
Organic clay-med. or high ilastcd: organic sll[
SHIGHLYORGANIC
P eat,humus, swamp soil with high organic content
SOILS
�
208-440-6276 * bjarnoldpe@msn.com (28) Post Office Box 190537 * Boise, Idaho 83719
ITE
ILUC
Abbreviations and Arrnnvmc
AASHTO
American Association of State Highway & Transportation Officials
ASTM
American Society for Testing and Materials
ACP
Asphaltic Concrete Pavement
BH
Bore Hole
IBC
International Building Code
ISPWC
Idaho Standard for Public Works Construction
ITD
Idaho Transportation Department
NP
Non Plastic
PCC
Portland Cement Concrete
PCF
Pounds per Cubic Foot
TP
--LIS-CS
Test Pit
Unified Soil Classification System
CL
Clay
ML
Silt
SM
Sand
NOTHING FOLLOWS
208-440-5276 * biarnoldpe@msn.com (29 ) Post Office Box 190537 * Boise, Idaho 83719
SITE
CONSULTING, LLC
Mr. Shawn Brownlee November 18, 2014
Trilogy Development Page 1 of 3
2358 South Titanium Place 14046-Ietter2
Meridian, Idaho 83642
Re: Groundwater Recommendation
Jump Creek Subdivision
NW Corner Blackcat & McMillan Roads
Meridian, Idaho
Dear Shawn;
As per your request, I have prepared the attached "Recommendations for Homebuilders" and
"Comments to Homeowners". These documents are intended to inform these parties of their
responsibility to construct and / or maintain homes that are free of water in the crawlspace- I have
forwarded this to Bailey Engineering for review and comment. These are stand alone documents
intended to be issued without cover letter, We appreciate this opportunity to be of service. Should
you have any questions or require additional information, please contact our office at your
convenience.
Respectfully
Bob J. Arnolc
cc: Bailey Engineering
208-440-6276 "' bjarnoldpe@msn.com ' Post Office Box 190537 * Boise, Idaho 83719
SITE
SULTING, LLC
RECOMMENDATIONS FOR HOMEBUILDERS
Jump Creek Subdivision
November - 2014
Bearing pressures of up to 1500 psf are available for foundation design,
After crawlspace excavation, inspection by a qualified soils engineer is recommended to
approve foundation support soils.
• Installation of at least two vertical drains in opposite corners of the crawlspace is
recommended, Vertical drain is a small excavation or boring of at least two square feet that
extends five feet below the foundation and is back filled with drain rock.
• It is recommended that the construction joint between the footing and the stem wall be sealed
with asphalt -based sealer.
• The trench beneath foundations, where utilities pass under the footing, must be properly
backfilled with soil or bentonite to prevent water from entering the crawlspace by way of utility
trenches,
• Soils containing fat clay or frozen clods or chunks are not recommended for backfill. The use
of these materials may result in voids or flow paths allowing surface water to enter the
crawlspace.
• Low-density foundation and utility trench backfill has been shown to be a major contributing
factor to water accumulating in crawlspaces throughout the Treasure Valley. Homebuilders
are encouraged to properly backfill all foundations and all utility trenches in accordance with
local building code requirements. This is especially critical on lots where bedrock, cemented
soils, and compacted fills are present below the foundation.
• Foundation elevation and site grading must promote drainage away from the foundation.
Unless the local code is more stringent, a minimum of FIVE percent slope for the first ten feet
from the residence is required.
• Crawlspace vents are to be above finished adjacent subgrade.
• Complete roof gutters are recommended with down spouts directed away from foundations
and not on to foundation backfill soils.
• Landscaping should be designed to promote drainage away from foundations,
• Flowerbeds and landscaped areas must be designed such that irrigation water and roof runoff
is not retained against foundations.
• Proper design and maintenance of sprinkler systems is required, Excessive watering may
lead to water entering the crawl space. Lawn area sprinklers should not spray toward
foundations or cause water to accumulate near foundations,
• Side lots between houses must provide for adequate drainage of both lots. Fences and
borders should not restrict the overland flow of storm runoff.
• This subdivision is located within the Treasure (Boise) Valley of Southwestern Idaho. This is
a high desert region with minimal annual rainfall, (< 13"/year). The proper selection of
grasses, bushes, and trees that thrive in such conditions will also prevent over application of
irrigation water.
NOTHING FOLLOWS
208-44M276 blarnoldpe@msn.com Post Office Box 190537 Boise, Idaho 83719
/SITE
ONSULTING, LLC
COMMENTS TO HOMEOWNERS
Jump Creek Subdivision
November - 2014
• Foundation elevation and site grading have been constructed to promote drainage away
from the foundation. Final, completed lot grading must promote drainage away from the
foundation. Modification of the grading near the residence may result in water entering
the crawlspace.
Roof gutters with down spouts have been or should be installed that direct storm water
away from foundations and not on to foundation backfill soils. Modification of downspouts
is not advisable without a plan to move storm water away from the foundation.
• This subdivision is located within the Treasure (Boise) Valley of Southwestern Idaho.
This is a high desert region with minimal annual rainfall. The proper selection of grasses,
bushes, and trees that thrive in such conditions will also prevent over application of
irrigation water.
• Landscaping should be designed to promote drainage away from foundations.
Flowerbeds and landscaped areas must be designed such that irrigation water and roof
runoff is not retained against foundations.
• Proper design, maintenance and scheduling of sprinkler systems are required. Excessive
watering is the largest source for water in local crawl spaces or basements. Sprinklers
should not spray toward foundations or cause water to accumulate near foundations.
• Over application of irrigation water is the single largest factor contributing to water
accumulating in crawlspaces. After occupancy, the settings for any automatic sprinkler
system should be reviewed and adjusted to apply the minimum amount of water required
for landscaping maintenance. It is recommended that the local water company or a lawn
care expert be consulted about the amount of water required.
• Runoff or drainage to adjacent property is not allowed without developer approval.
NOTHING FOLLOWS
208-440-6276 • bjarnoldpe@msn.com " Post Office Box 190537 Boise, Idaho 83719