Att_9_-_Geotechnical_Report_Combined.pdf

Geotechnical Study Steinaker Service Canal Enclosure Prepared for Bowen Collins & Associates, Inc.

April 2013

668 East 12225 South, Suite 203 Draper, Utah 84020

801.849.0055

April 24, 2013

Mr. Jordan Oyler Bowen Collins & Associates, Inc.

754 East 14000 South Draper, Utah 84020

Re: Geotechnical Study, Uintah County, Utah.

Dear Jordan:

This letter summarizes the geotechnical study authorized by Bowen Collins & Associates, Inc. (BCA) for the proposed canal enclosure project; based on our proposal dated April 1, 2013.

SCOPE OF SERVICES

The purpose of the study was to characterize subsurface materials at eleven (11) locations along the Steinaker Service Canal alignment between approximate Stations 340+00 and 595+00. To accomplish the scope of services the following tasks were performed:

• Task 1 Field Studies – Eleven (11) test pits were excavated to depths of 4 to 8 feet as directed by Bowen Collins & Associates, Inc. Samples of subsurface materials were collected by hand from the test pits. Subsurface conditions were logged at the time of excavation by a licensed engineer.

• Task 2 Laboratory Testing – Select materials from test pit samples were tested in a geotechnical laboratory.

• Task 3 Analysis and Letter – Results from Tasks 1 and 2 were compiled and summarized in this letter.

Design and construction related recommendations were not included as part of this study.

PROJECT BACKGROUND

We understand the Uintah Water Conservancy District (District) is planning to enclose approximately 5 miles of the lower section of the Steinaker Service Canal.

BCA has been retained to provide design services which we understand will likely included a 42- to 63-inch nominal size HDPE pipe for the enclosure. Preliminary grading suggests cuts on the order of 6 to 8 feet below the existing canal invert will be needed, with the overall objective of minimizing cuts/fills, thus providing an overall mass balance.

FIELD STUDIES

Subsurface soils were studied on April 2, 2013 by excavating eleven (11) test pits located along the Steinaker Service Canal alignment. BCA provided plan and profile figures of the canal alignment with all eleven proposed test pit locations identified by station. The locations of the test pits, as shown on the provided figures, were adjusted in the field as required by District representatives. A Vicinity Map showing the approximate location of the canal enclosure project is included on Figure 1. The approximate locations of the test pits are plotted on Figure 2.

Test pit locations were mapped using a hand held Garmin GPS device; suggesting that the actual locations may vary up to 33 feet, according to the accuracy reported for the device. Test pit data is summarized in Table 1.

Test pits were excavated using a rubber tire John Deere 410J backhoe provided by the District. Test pits were excavated to depths of 4 to 8 feet below the existing ground surface, and were typically 3 to 6 feet in width with a working base of 5 to 11 feet to provide room for logging. At the direction of BCA, all test pits were excavated in the canal invert. Due to limitations on entering the canal (such as embankment side slopes, bridges, pipe crossings, etc.), the backhoe excavated all test pits, except for TP-02, from the access road atop the east canal embankment. Test pit TP-02 was completed with the backhoe located in the canal invert. Given the vertical and horizontal distances between the canal invert and the top of the canal embankment, in conjunction with the maximum reach of the excavator bucket, test pits TP-03, TP- 06, TP-07, TP-08 and TP-10 were limited from reaching the desired 8 foot excavation depth.

Test pits were logged by a licensed engineer during the excavation process. Material descriptions were developed by observing samples collected during the excavation process. Soils were classified following Unified Soil Classification System (USCS) procedures. Laboratory test results were used to supplement field descriptions and adjustments were made to field logs where appropriate. Logs of the test pits are presented in Figures 3 through 13; a legend of soil descriptions is included in Figure 14.

Photo Log

Photographs were taken along the canal alignment at each test pit location. A photo log is included in Figures 18 through 39, with the approximate stationing and description listed for each photograph.

LABORATORY TESTING

Selected samples obtained from test pits were tested in a geotechnical laboratory. In particular, the testing consisted of:

1. ASTM D422 Test Method for Particle-Size Analysis of Soils.

2. ASTM D2216 Test Method for Laboratory Determination of Water (Moisture)

Content of Soil, Rock, and Soil-Aggregate Mixtures

3. ASTM D4318 Test Method for Liquid Limit, Plastic Limit, and Plasticity Index of Soils

Laboratory test results for the test holes are summarized on Table 2 and graphically in Figures 15 and 16. Sensitivity vs. Effective Stress Relationships developed from laboratory data are plotted on Figure 17.

SITE CONDITIONS

The project site is located along the lower section of the Steinaker Service Canal between approximate Stations 340+00 and 595+00. Within project limits, the canal is an earthen lined canal with grassy vegetation located along the entire length of the inboard canal embankment. The canal invert slopes gently downward to the southeast from an elevation of approximately 5438 feet near TP-11 to approximately 5431 feet near TP-01. Freestanding water, to approximate depths of between about 2 to 12 inches, is located at the northern end of the project near test pits TP-10 and TP-11. According to the District, the water is from both infiltration and drainage into the canal. Numerous paved and dirt road crossings, farm bridges, pipe drains, turnouts, check dams and siphons are located along the canal within project limits.

Geology

Near surface geology between TP-01 and TP-04, and for a short segment between TP-09 and TP-10, was mapped by Sprinkel (2007) as Upper Cretaceous-age Mancos Shale consisting of dark gray, soft, slope-forming calcareous shale containing beds of siltstone and bentonitic clay. Near surface geology at TP-04 is adjacent to the boundary between Mancos Shale and Holocene and Pleistocene-age undivided Piedmont and Basin alluvium consisting of variably consolidated, poorly to moderately sorted sand, gravel, cobbles and boulders deposited on near-planar bedrock surfaces. Near surface geology between TP-04 and TP-11, except for the short segment of Mancos Shale between TP-10 and TP-11, was mapped as Holocene-age mixed alluvium and eolian deposits consisting of unconsolidated alluvial mud, silt, and sand mixed with windblown sand and silt.

Some areas of the Mancos shale formation tend to swell/heave when wetted. Plastic limit and liquid limit testing of materials found in the test pits (see Figure 16) show tested materials exhibit low to medium plasticity. Based on results from these index tests and our understanding that the canal enclosure will utilize HDPE (flexible) pipe materials, we believe risks associated with adverse performance related to swelling of the clay materials to be low.

Subsurface Conditions

In general, native materials found during our field studies include clays (CL), silty clays (CL-ML), sandy clays (CL), clayey sands (SC), gravel (GW) and clayey gravel (GC). Except for the sand found in TP-09, granular materials were only found between TP-01 and TP-05. Oversized material, including cobbles and occasional boulders, were found in each of the gravel layers. We interpret portions of clay deposits in TP-06, TP-07, TP-08 and TP-10 to be weathered bedrock due to the blocky structure of the material and breakdown/deterioration observed when exposed. Though the weathered bedrock in TP-10 was more difficult to excavate in relation to the weathered bedrock in other test pits, the backhoe was able to excavate two feet into the weathered bedrock.

Fill material, which we believe resulted from sedimentation in the canal invert, was found in TP-05 and TP-07 through TP-11. Typical sedimentation depths were less than 12 inches, though a sedimentation depth of about 18 inches was found in TP-05 immediately upstream from the siphon under 4000 South, near Station 515+80. Fill material, which consisted of mottled clay with sand, was also found in TP-04 to a depth of about 3 feet. A stream bed crosses the canal near the location of TP-04, and based on discussions with the District, the fill was placed to backfill the stream bed at this location.

Materials with collapse potential were observed in TP-01, TP-02, TP-04, TP-08, TP- 09, TP-10, and TP-11. In general these materials were observed in the upper 2 feet, with the exception of TP-01 where pinhole structure was observed as deep as 4 feet.

These types of materials have the potential to produce surface settlements under additional load with increase in moisture.

General stratigraphy for the site could not be developed due to the large distance between exploration points (approximately ½ mile) and the nature of the depositional environment. Stratification lines shown on the logs represent approximate boundaries between soil types for the particular test pit location, using the field data collected during our study. Therefore, interpolation of subsurface conditions between and beyond the study locations may not be appropriate and/or representative.

Groundwater

Groundwater was found in test pits TP-04, TP-06, TP-08, TP-09 and TP-11 at depths ranging from the 0 to 8 feet at the time of our field studies on April 2, 2013. Test pits

Test Pit

Date

Excavated Long. Lat. Elev. (ft) a

Approx.

Station

Total depth

(ft)

Water depth b

(ft)

Water depth c

(ft) Excavation Method Comments

TP-01 4/2/13 -109.5079 40.3756 5409 594+00 8.0 N/E

d

N/M John Deere 410J Backhoe

TP-02 4/2/13 -109.5081 40.3810 5431 571+00 8.0 N/E N/M John Deere 410J Backhoe

TP-03 4/2/13 -109.5136 40.3868 5435 543+60 7.5 N/E N/M John Deere 410J Backhoe

TP-04 4/2/13 -109.5204 40.3913 5436 515+80 8.0 8.0 6.0 John Deere 410J Backhoe

TP-05 4/2/13 -109.5245 40.3976 5431 487+20 8.0 N/E N/M John Deere 410J Backhoe

TP-06 4/2/13 -109.5296 40.4007 5441 468+60 6.0 5.0 4.0 John Deere 410J Backhoe

TP-07 4/2/13 -109.5344 40.4060 5450 440+00 7.0 N/E N/M John Deere 410J Backhoe

TP-08 4/2/13 -109.5361 40.4120 5458 410+80 7.5 5.0 4.0 John Deere 410J Backhoe

TP-09 4/2/13 -109.5403 40.4179 5454 382+00 5.5 1.0 N/M John Deere 410J Backhoe

TP-10 4/2/13 -109.5447 40.4239 5423 356+20 4.0 N/E N/M John Deere 410J Backhoe

TP-11 4/2/13 -109.5492 40.4254 5438 341+80 4.0 GS N/M John Deere 410J Backhoe

Notes: a: Elevations collected using a hand held Garmin GPS device b: Ground water depth measured at time of excavation on 4/2/13 c: Ground water depth measured on 4/4/13 d: N/E = Not Encountered; N/M = Not Measured; GS = Ground Surface

Table 1 Test Pit Data

Steinaker Service Canal Enclosure (13GCI314)

6 7 8 9 10 11 12 13 7 8 9 10 11 12 13 14 15 16

T e s t H o le

D e p th ft

L L

P L

P I

C o h e s iv e I n d e x C

I

L iq u id it y I n d e x L

I

C O

B B

L E

S

(3

G R

A V

E L

(N o

.4 c o a rs e G

R A

V E

L

(3 /4

-3 fi n e G

R A

V E

L

(N o

.4 -3

/4

S A

N D

(N o

.2

-N o .4 c o a rs e S

A N

D

(N o

.1

-N o

.4 m e d iu m S

A N

D

(N o

.4

-N o

.1 fi n e S

A N

D

(N o

.2

-N o .4

F

IN

E S

N o .2

-i n m m

-i n m m

-i n m m

.5

-i n

.5 m m

/4

-i n m m

/8

-i n

.5 m m

N o

.4

.7 m m

N o

.1 m m

N o

.2

.8 m m

N o

.4

.4 m m

N o

.6

.2 m m

N o

.1

.1 m m

N o

.2

.0 m m

TP-01 1-2 21 40 19 21 1.11 0.1

TP-01 4-5 11 23 18 5 0.28 -1.5

TP-01 6-7 10 23 44 37 7 21 2 3 15 13 100 100 77 59 40 36 33 31 30 28 25 19 13

TP-02 4.5-5.5 6 26 40 25 16 29 7 10 12 5 100 87 74 62 49 40 34 27 21 17 11 8 5

TP-03 3-4 16 26 15 11 0.73 0.1

TP-04 1-2 17 24 16 8 0.5 0.2

TP-04 4.5-5 19 0 0 0 0 25 0 1 24 75 100 100 100 100 100 100 100 99 99 98 95 91 75

TP-04 7-8 12 32 43 34 9 19 4 5 10 7 100 86 68 48 34 29 25 21 19 16 12 9 7

TP-05 0-1 17 30 16 14 0.88 0.1

TP-05 2-3 11 0 0 0 0 65 0 2 63 35 100 100 100 100 100 100 100 100 99 98 84 61 35

TP-05 4.5-5.5 17 23 16 7 0.44 0.2

TP-06 3-4 18 36 18 18 1 0.0

TP-07 4-5 20 42 19 23 1.21 0.0

TP-08 3-4 21 30 20 10 0.5 0.1

TP-08 7-7.5 19 32 18 14 0.78 0.1

TP-09 3-4 23 0 1 0 1 58 0 2 56 42 100 100 100 100 100 100 100 99 99 98 88 69 42

TP-10 3-4 13 33 17 16 0.94 -0.2

TP-11 2-3 25 0 0 0 0 49 0 1 48 51 100 100 100 100 100 100 100 100 100 99 95 80 51

Notes: a: Moisture content performed on minus 3/4 inch material b: LL = Liquid Limit; PL = Plastic Limit; PI = Plasticity Index

Table 2 Summary of Laboratory Test Results

M o is tu re c o n te n t a

Atterberg Limits b

D ry u n it w e ig h t (p c f)

M o is t S a t.

u n it w e ig h t

(p c f)

Grain-Size Analysis (Percent Finer)Grain-Size

Naples

Vernal

Figure 1

0 5,000 10,0002,500

FeetSteinaker Service Canal Enclosure

Vicinity Map

J

P R

O J E

C T

S \2

\1

G

C I3

S te in a k e rS e rv ic e C a n a l\ D ra w in g s \A rc G

IS

\W o rk

\V ic in it y M a p

.m x d

/2

/2

:2

:1

P

M

LEGEND

Steinaker Service Canal

Municipalities

Steinaker Reservoir

!A

!A

!A

!A

!A

!A

!A

!A

!A

!A

!A

2500 South

3500 South

4000 South

4500 South

5000 South

H i g h w a y

/ 1

E a s t

H i g h w a y

E a s t

V e rn a l A v e n u e

W e s t

TP-11

TP-10

TP-09

TP-08

TP-07

TP-06

TP-05

TP-04

TP-03

TP-02

TP-01

Figure 2

0 1,200 2,400600

FeetSteinaker Service Canal Enclosure

Test Pit Location Map

J

P R

O J E

C T

S \2

\1

G

C I3

S te in a k e rS e rv ic e C a n a l\ D ra w in g s \A rc G

IS

\W o rk

\T e s t

P it L o c a ti o n M a p

.m x d

/2

/2

:2

:2

P

M

LEGEND

!A Test Pit Locations

Steinaker Service Canal

CLAY, with sand, moist, light reddish brown, with rootlets and pinholes, (CL)

CLAY, silty with sand and gravel, moist, light reddish brown, with rootlets, (CL-ML)

GRAVEL, clayey with sand and cobbles, moist, light reddish brown, sub-rounded, with occasional 12 inch boulders, (GP-GC)

Bottom of Test Pit at 8.0 feet

N u m b e r

S a m p le T y p e

D e p th fe e t

FIELD NOTES

G ra p h ic L o g

MATERIAL DESCRIPTION

E le v a ti o n fe e t

Groundwater Level (feet) N/E

Logged By

Approximate Width (feet) 3

R. Cole

East/West

B. Conder

8.0

Excavation Equipment

4/2/13

John Deere 410J Backhoe

Approximate Length (feet)

Date Measured

Excavation Contractor

Date(s) Excavated

5431.0

Comments

Approximate Depth (feet)

4/2/13 Approximate Surface Elevation (feet)

Approximate Pit TrendUintah Water Conservancy District

Checked By

Figure 3

Log of Test Pit TP-01Project Location: Uintah County

Project: Steinaker Service Canal Enclosure

Project Number: 13GCI314

T E

S T

P

IT

S

T H

O L

E L

O G

S

S T

E

IN

A K

E R

.G

J

G

R H

A R

T .G

D

/2

/1

GRAVEL, clayey with sand, moist, light reddish brown, subrounded, with rootlets, (GC)

GRAVEL, clayey with sand, moist, light reddish brown, cemented, (GC)

GRAVEL, with sand and cobbles, moist, light reddish brown, subrounded, cobbles to 12 inches, (GW)

Bottom of Test Pit at 8.0 feet

N u m b e r

S a m p le T y p e

D e p th fe e t

FIELD NOTES

G ra p h ic L o g

MATERIAL DESCRIPTION

E le v a ti o n fe e t

Groundwater Level (feet) N/E

Logged By

Approximate Width (feet) 3.5

R. Cole

North/South

B. Conder

8.0

Excavation Equipment

4/2/13

John Deere 410J Backhoe

Approximate Length (feet)

Date Measured

Excavation Contractor

Date(s) Excavated

5432.0

Comments

Approximate Depth (feet)

4/2/13 Approximate Surface Elevation (feet)

Approximate Pit TrendUintah Water Conservancy District

Checked By

Figure 4

Log of Test Pit TP-02Project Location: Uintah County

Project: Steinaker Service Canal Enclosure

Project Number: 13GCI314

T E

S T

S

T H

O L

E L

O G

S

S T

E

IN

A K

E R

.G

R H

A R

T .G

- Maximum reach of backhoe

CLAY, with sand, moist, light brown grades to light reddish brown, (CL)

Bottom of Test Pit at 7.5 feet

N u m b e r

S a m p le T y p e

D e p th fe e t

FIELD NOTES

G ra p h ic L o g

MATERIAL DESCRIPTION

E le v a ti o n fe e t

Groundwater Level (feet) N/E

Logged By

Approximate Width (feet) 3

R. Cole

North/South

B. Conder

7.5

Excavation Equipment

4/2/13

John Deere 410J Backhoe

Approximate Length (feet)

Date Measured

Excavation Contractor

Date(s) Excavated

5433.0

Comments

Approximate Depth (feet)

4/2/13 Approximate Surface Elevation (feet)

Approximate Pit TrendUintah Water Conservancy District

Checked By

Figure 5

Log of Test Pit TP-03Project Location: Uintah County

Project: Steinaker Service Canal Enclosure

Project Number: 13GCI314

T E

S T

S

T H

O L

E L

O G

S

S T

E

IN

A K

E R

.G

R H

A R

T .G

CLAY, with sand, moist, mottled light yellow brown to reddish brown, (CL) FILL

CLAY, sandy, moist, dark brown to black, with roots and organics, (CL)

CLAY, with sand, wet, reddish brown, with rootlets, (CL)

GRAVEL, with clay, sand and cobbles, wet, light brown, subrounded, (GW-GC)

Bottom of Test Pit at 8.0 feet

N u m b e r

S a m p le T y p e

D e p th fe e t

FIELD NOTES

G ra p h ic L o g

MATERIAL DESCRIPTION

E le v a ti o n fe e t

Groundwater Level (feet) 6

Logged By

Approximate Width (feet) 3

R. Cole

Northeast/Southwest

B. Conder

8.0

Excavation Equipment

4/2/13

John Deere 410J Backhoe

Approximate Length (feet)

Date Measured

Excavation Contractor

Date(s) Excavated

5434.0

Comments

Approximate Depth (feet)

4/4/13 Approximate Surface Elevation (feet)

Approximate Pit TrendUintah Water Conservancy District

Checked By

Figure 6

Log of Test Pit TP-04Project Location: Uintah County

Project: Steinaker Service Canal Enclosure

Project Number: 13GCI314

T E

S T

S

T H

O L

E L

O G

S

S T

E

IN

A K

E R

.G

R H

A R

T .G

- Fill deposits located upstream from siphon under road

CLAY, with sand, moist, dark grayish brown, (CL) FILL

SAND, clayey, moist, reddish brown, fine grained, (SC)

GRAVEL, clayey with sand, moist, light reddish brown, subrounded, (GC)

CLAY, silty with sand, moist, mottled reddish brown to light reddish brown, (CL-ML)

GRAVEL, clayey with sand and cobbles, moist, reddish brown, subrounded, cobbles to 8 inches, (GC)

Bottom of Test Pit at 8.0 feet

N u m b e r

S a m p le T y p e

D e p th fe e t

FIELD NOTES

G ra p h ic L o g

MATERIAL DESCRIPTION

E le v a ti o n fe e t

Groundwater Level (feet) N/E

Logged By

Approximate Width (feet) 3

R. Cole

Northeast/Southwest

B. Conder

8.0

Excavation Equipment

4/2/13

John Deere 410J Backhoe

Approximate Length (feet)

Date Measured

Excavation Contractor

Date(s) Excavated

5435.0

Comments

Approximate Depth (feet)

4/2/13 Approximate Surface Elevation (feet)

Approximate Pit TrendUintah Water Conservancy District

Checked By

Figure 7

Log of Test Pit TP-05Project Location: Uintah County

Project: Steinaker Service Canal Enclosure

Project Number: 13GCI314

T E

S T

S

T H

O L

E L

O G

S

S T

E

IN

A K

E R

.G

R H

A R

T .G

CLAY, moist to wet, mottled olive gray to olive brown, varved, blocky structure, weathered bedrock, iron oxide staining, (CL)

Bottom of Test Pit at 6.0 feet

N u m b e r

S a m p le T y p e

D e p th fe e t

FIELD NOTES

G ra p h ic L o g

MATERIAL DESCRIPTION

E le v a ti o n fe e t

Groundwater Level (feet) 4

Logged By

Approximate Width (feet) 3

R. Cole

East/West

B. Conder

6.0

Excavation Equipment

4/2/13

John Deere 410J Backhoe

Approximate Length (feet)

Date Measured

Excavation Contractor

Date(s) Excavated

5436.0

Comments

Approximate Depth (feet)

4/4/13 Approximate Surface Elevation (feet)

Approximate Pit TrendUintah Water Conservancy District

Checked By

Figure 8

Log of Test Pit TP-06Project Location: Uintah County

Project: Steinaker Service Canal Enclosure

Project Number: 13GCI314

T E

S T

S

T H

O L

E L

O G

S

S T

E

IN

A K

E R

.G

R H

A R

T .G

CLAY, with sand, moist, dark brown, (CL) FILL

CLAY, moist, olive gray to olive brown, varved, blocky structure, weathered bedrock, iron oxide staining, (CL)

Bottom of Test Pit at 7.0 feet

N u m b e r

S a m p le T y p e

D e p th fe e t

FIELD NOTES

G ra p h ic L o g

MATERIAL DESCRIPTION

E le v a ti o n fe e t

Groundwater Level (feet) N/E

Logged By

Approximate Width (feet) 3

R. Cole

North/South

B. Conder

7.0

Excavation Equipment

4/2/13

John Deere 410J Backhoe

Approximate Length (feet)

Date Measured

Excavation Contractor

Date(s) Excavated

5436.0

Comments

Approximate Depth (feet)

4/2/13 Approximate Surface Elevation (feet)

Approximate Pit TrendUintah Water Conservancy District

Checked By

Figure 9

Log of Test Pit TP-07Project Location: Uintah County

Project: Steinaker Service Canal Enclosure

Project Number: 13GCI314

T E

S T

S

T H

O L

E L

O G

S

S T

E

IN

A K

E R

.G

R H

A R

T .G

CLAY, moist, dark brown, with rootlets, (CL) FILL

CLAY, with sand, moist, olive gray to olive brown, varved, blocky structure, weathered bedrock, (CL)

Bottom of Test Pit at 7.5 feet

N u m b e r

S a m p le T y p e

D e p th fe e t

FIELD NOTES

G ra p h ic L o g

MATERIAL DESCRIPTION

E le v a ti o n fe e t

Groundwater Level (feet) 4

Logged By

Approximate Width (feet) 3

R. Cole

Northeast/Southwest

B. Conder

7.5

Excavation Equipment

4/2/13

John Deere 410J Backhoe

Approximate Length (feet)

Date Measured

Excavation Contractor

Date(s) Excavated

5437.0

Comments

Approximate Depth (feet)

4/4/13 Approximate Surface Elevation (feet)

Approximate Pit TrendUintah Water Conservancy District

Checked By

Figure 10

Log of Test Pit TP-08Project Location: Uintah County

Project: Steinaker Service Canal Enclosure

Project Number: 13GCI314

T E

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T H

O L

E L

O G

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S T

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A K

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R H

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T .G

- Trench walls collapsed during excavation beginning at 2.0 feet

- Test pit terminated due to collapsing trech walls

CLAY, with sand, wet, dark brown, with rootlets, (CL) FILL

SAND, clayey, wet, reddish brown, fine grained, (SC)

Bottom of Test Pit at 5.5 feet

N u m b e r

S a m p le T y p e

D e p th fe e t

FIELD NOTES

G ra p h ic L o g

MATERIAL DESCRIPTION

E le v a ti o n fe e t

Groundwater Level (feet) 1

Logged By

Approximate Width (feet) 6

R. Cole

East/West

B. Conder

5.5

Excavation Equipment

4/2/13

John Deere 410J Backhoe

Approximate Length (feet)

Date Measured

Excavation Contractor

Date(s) Excavated

5438.0

Comments

Approximate Depth (feet)

4/2/13 Approximate Surface Elevation (feet)

Approximate Pit TrendUintah Water Conservancy District

Checked By

Figure 11

Log of Test Pit TP-09Project Location: Uintah County

Project: Steinaker Service Canal Enclosure

Project Number: 13GCI314

T E

S T

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T H

O L

E L

O G

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S T

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A K

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R H

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- 2 to 3 inches of standing water in canal

- Difficult excavation

- Maximum reach of backhoe

CLAY, with sand, wet, dark brown, with rootlets, (CL) FILL

CLAY, moist, olive brown, blocky structure, weathered bedrock, iron oxide staining, (CL)

Bottom of Test Pit at 4.0 feet

N u m b e r

S a m p le T y p e

D e p th fe e t

FIELD NOTES

G ra p h ic L o g

MATERIAL DESCRIPTION

E le v a ti o n fe e t

Groundwater Level (feet) N/E

Logged By

Approximate Width (feet) 3

R. Cole

East/West

B. Conder

4.0

Excavation Equipment

4/2/13

John Deere 410J Backhoe

Approximate Length (feet)

Date Measured

Excavation Contractor

Date(s) Excavated

5438.0

Comments

Approximate Depth (feet)

4/2/13 Approximate Surface Elevation (feet)

Approximate Pit TrendUintah Water Conservancy District

Checked By

Figure 12

Log of Test Pit TP-10Project Location: Uintah County

Project: Steinaker Service Canal Enclosure

Project Number: 13GCI314

T E

S T

S

T H

O L

E L

O G

S

S T

E

IN

A K

E R

.G

R H

A R

T .G

- 12 inches of standing water in canal

- Trench walls collapsed during excavation beginning at 1.0 feet

- Test pit terminated due to collapsing trech walls

CLAY, with sand, wet, dark brown to black, with rootlets, (CL) FILL

CLAY, sandy, wet, brown, (CL)

Bottom of Test Pit at 4.0 feet

N u m b e r

S a m p le T y p e

D e p th fe e t

FIELD NOTES

G ra p h ic L o g

MATERIAL DESCRIPTION

E le v a ti o n fe e t

Groundwater Level (feet) 0

Logged By

Approximate Width (feet) 5

R. Cole

Northeast/Southwest

B. Conder

4.0

Excavation Equipment

4/2/13

John Deere 410J Backhoe

Approximate Length (feet)

Date Measured

Excavation Contractor

Date(s) Excavated

5438.0

Comments

Approximate Depth (feet)

4/2/13 Approximate Surface Elevation (feet)

Approximate Pit TrendUintah Water Conservancy District

Checked By

Figure 13

Log of Test Pit TP-11Project Location: Uintah County

Project: Steinaker Service Canal Enclosure

Project Number: 13GCI314

T E

S T

S

T H

O L

E L

O G

S

S T

E

IN

A K

E R

.G

R H

A R

T .G

Other Material Symbols Sample Types

Boulders / Cobbles COBBLES

BOULDERS

Liquid limit (%)

Plasticity Chart

Criteria 1/16" to 1/2" 1/2" to 12" <= 1 per ft. thickness > 1 per ft. thickness

GW

GP

GM

GC

SW

SP

SM

SC

CL

ML

OL

CH

MH

OH

> 50% (by volume) particles > 3"

Topsoil

Boulders (>12"); Cobbles (>3" and <12")

P la st ic ity in de x

Stratification

SPT

<4

4-10

10-30

30-50

>50 Description

Boulder

Cobble

Coarse Gravel

Fine Gravel

Coarse Sand

Medium Sand

Fine Sand

Criteria

>12" : larger than a basketball

3-12" : larger than a grapefruit

3/4-3" : larger than a grape

No.4-3/4" : larger than a pea

No.10-4 : larger than rock salt grain

No.40-4 : larger than window screen opening

No.200-40 : larger than a sugar grain

Descriptors for Particle Size

Descriptios for Particle Angularity Description Angular Subangular Subrounded Rounded

Criteria Sharp edges, rel. plane sides, unpolished surface Similar to angular, but with rounded edges Nearly plane sides, well-rounded corners & edges Smoothly curved sides and no edges

Abbreviated Soil Classification Symbols (after ASTM D2488 X.5)

Prefix Suffix s = sandy s = with sand g = gravelly g = with gravel c = with cobbles b = with boulders

Abbreviated system for supplementary presentations when complete description is referenced. Examples:

Group Symbol and Full Name Abbreviated Sandy Lean CLAY (CL) s(CL) Poorly Graded SAND with silt and gravel (SP-SM)g Poorly Graded GRAVEL with sand, cobbles, (GP)scb and boulders (GP) Gravelly SILT with sand and cobbles (ML) g(ML)sc

General Notes:

1) Strata graphic lines on the logs represent approximate boundaries.

2) No warranty is provided as to the continuity of soil conditions between points explored and sample locations.

3) Logs represent soil conditions observed at the point of exploration on the date indicated.

4) Visual methods were used to classify the materials in general accordance with the Unified Soils Classification Systems; actual designations based on laboratory methods may vary.

Dr (%)

0-15

15-35

35-65

65-85

85-100

Modifiers Est. (%)

<5

5-12

>12

Description

Trace

Some

With

Figure 14

Asphalt

Auger Cuttings California Sampler

Continuous sampler Rock Core

Grab Sample Modified California Sampler

No Recovery Other (see remarks)

Shelby Tube Piston Sampler (Shelby Tube)

Standard Penetration Test (SPT) Split Spoon

Cont. Sample Vane Shear

Major Soil Divisions

>50% of coarse fraction retained on No. 4 Sieve

SILTS and CLAYS liquid limit < 50

FI

N

E -G

R A

IN

E

D S

O

IL

S >5

0% P as si ng N o.

S ie ve

C O

A R

S E

-G R

A

IN

E D

S O

IL

S

>5 0% re ta in ed on N o.

si ev e

>50% of coarse fraction passing the No. 4 sieve

SILTS and CLAYS liquid limit < 50

1) CF > 30%: + Sandy/Gravelly

2) CF = 15-30% + with sand/gravel

Inorganic

Organic

1) CF > 30%: + Sandy/Gravelly

2) CF = 15-30% + with sand/gravel

Inorganic

Organic

OH & MH

Description Seam Layer Occasional Frequent

MC

<6

6-15

15-42

42-72

>72

Clean GRAVELS (little or no fines)

GRAVELS with fines (appreciable amount of fines)

SANDS with fines (appreciable amount of fines)

Clean SANDS (little or no fines)

Typical Names

GRAVELS

Material Types

SANDS

Group Symbol and Legend

Primarily Organic Matter; Organic Odor PEATPT

Well-Graded GRAVEL, GRAVEL-sand mixtures, few fines

Poorly-Graded GRAVEL, GRAVEL-sand mixtures, few fines

Silty GRAVEL, GRAVEL-sand silt mixtures

Clayey GRAVEL, GRAVEL-sand clay mixtures

Well-Graded SAND, SAND-gravel mixtures, few fines

Poorly-Graded SAND, SAND-gravel mixtures, few fines

Silty SAND, SAND-silt mixtures

Clayey SAND, SAND-clay mixtures

Lean CLAY, Gravelly/Sandy CLAY, low to med. plasticity

SILT, Gravelly/Sandy SILT, no to slight plasticity

Organic CLAY or SILT

Fat CLAY, Gravelly/Sandy Fat CLAY, high plasticity

Elastic SILT, Gravelly/Sandy Elastic SILT, low to high plasticity

Organic CLAY or SILT

Highly orgainc soils

CL

CH

0 10 20 30 40 50 60 70 80 90 100 110 120

Concrete

Fill

Bedrock

"A" LINE

CL-ML

Consistency very soft soft med. stiff stiff very stiff hard

Descriptors for Coarse Grained Soils

Descriptors for Fine Grained Soils

Apparent Density very loose loose med. dense dense very dense

SPT

<2

2-4

4-8

8-15

15-30

>30

MC

<2

2-4

4-10

10-19

19-37

>37

CAL

<2

2-5

5-11

11-22

22-45

>45

SPT - Standard split spoon (SPT): 2" OD, 1.375" ID MC - Modified California: 2.5" OD, 1.875" ID CAL - California: 3" OD, 2.375" ID

CAL

<8

8-20

20-56

56-96

>96

Apparent water level Measured water level

Descriptors for Moisture

Su (psf)

< 250

250-500

500-1000

1000-2000

2000-4000

>4000

Criteria

Absence of moisture, dusty, dry to the touch

Damp but no visible water

Visible free water, usually soil is below water table

Description

Dry

Moist

Wet

Unified Soil Classification System (USCS)

Legend to Soil Descriptions

100 10 1 0.1 Grain size (mm) [40]

P e rc e n t fi n e r b y w e ig h t

[2

12-in 5-in 4-in 3-in 1.5-in 3/4-in 3/8-in No.4 No.10 No.20 No.40 No.60 No.100 No.200

COBBLES

coarse

GRAVEL

fine coarse medium

SAND

fine

FINES

TP-01 at 6-7

TP-02 at 4.5-5.5

TP-04 at 4.5-5

TP-04 at 7-8

TP-05 at 2-3

TP-09 at 3-4

TP-11 at 2-3

Steinaker Service Canal Enclosure (13GCI314) Figure 15

Grain-Size Analysis

0 10 20 30 40 50 60 70 80 90

Liquid limit, LL (%)

P la s ti c it y in d e x P I

Low Plasticity Medium Plasticity High Plasticity Very High Plasticity

CL-ML

CL

ML

CH

MH

10 20 30 40 50 60

PL (%)

P I

CI=0.2

CI=0.4

CI=0.6

CI=0.8

CI=1.0

(SILT)

(slightly clayey SILT)

(clayey SILT)

(very silty CLAY)

(silty CLAY)

(CLAY)

TP-01 at 1-2

TP-01 at 4-5

TP-03 at 3-4

TP-04 at 1-2

TP-05 at 0-1

TP-05 at 4.5-5.5

TP-06 at 3-4

TP-07 at 4-5

TP-08 at 3-4

TP-08 at 7-7.5

TP-10 at 3-4

Steinaker Service Canal Enclosure (13GCI314)

Casagrande's Plasticity Chart (Atterberg Limits)

Figure 16

U Line A Line

100 1000 10000 200 500 2000 5000 20000

Effective stress (psf)

-0.5

0.5

1.5

2.5

L iq u id it y In d e x (w n P L (L L -P L

TP-01 at 1-2

TP-03 at 3-4

TP-04 at 1-2

TP-05 at 4.5-5.5

TP-06 at 3-4

TP-07 at 4-5

TP-08 at 3-4

TP-08 at 7-7.5

TP-10 at 3-4

Steinaker Service Canal Enclosure (13GCI314)

Sensitivity, LI, and Effective Stress Relationships (Mitchell,1993)

Figure 17

Contours of sensitivity

Figure 18: Sta. 594+00, Completed backfill at TP-01.

Figure 19: Sta. 571+00, Excavating TP-02 from canal invert.

Figure 20: Sta. 571+00, Excavating TP-02 from canal invert.

Figure 21: Sta. 571+00, View of trench walls in TP-02.

Figure 22: Sta. 543+60, View of trench walls in TP-03.

Figure 23: Sta. 543+60, Excavating TP-03 from east canal embankment.

Figure 24: Sta. 515+80, View of trench walls in TP-04.

Figure 25: Sta. 515+80, View of canal at TP-04.

Figure 26: Sta. 487+20, Excavating TP-05 from east canal embankment.

Figure 27: Sta. 487+20, View of canal at TP-05.

Figure 28: Sta. 468+60, Excavating TP-06 from east canal embankment.

Figure 29: Sta. 468+60, Groundwater in the bottom of TP-06.

Figure 30: Sta. 440+00, Excavating TP-07 from east canal embankment.

Figure 31: Sta. 440+00, View of trench walls in TP-07.

Figure 32: Sta. 410+80, Excavating TP-08 from east canal embankment.

Figure 33: Sta. 410+80, View of trench walls in TP-08.

Figure 34: Sta. 382+00, View of trench walls in TP-09 which collapsed during excavation.

Figure 35: Sta. 382+00, Excavating TP-09 from east canal embankment.

Figure 36: Sta. 356+20, Excavating TP-10 from east canal embankment.

Figure 37: Sta. 356+20, View of trench walls in TP-10. Note standing water adjacent to test pit.

Figure 38: Sta. 341+80, View of trench walls in TP-11 which collapsed during excavation.

Figure 39: Sta. 341+80, View of canal at TP-11. Note standing water adjacent to test pit.

should be maintained a minimum of 2 feet below the base of excavation while excavation is open. Temporary shoring / trench boxes and/or significantly flatter slopes should be used when dewatering cannot achieve the 2 feet minimum. These areas should be evaluated on a case-by-case basis by a qualified geotechnical engineer during construction.

The contractor should be aware that dewatering will be needed during construction. In order to maintain groundwater levels a minimum of 2 feet below the base of excavation, we anticipate groundwater levels will need to be lowered on the order of 8 to 10 feet.

Dewatering systems should be designed to prevent migration of finer materials, quick conditions, and subgrade softening.

The contractor should rely upon his own methods to determine and maintain safe and stable slopes during construction subject to his particular construction procedures and to those subsurface conditions more fully exposed during construction. All excavations should comply at a minimum with the Occupational Safety and Health Administration’s (OSHA) construction standards for excavations and any other applicable standards. All excavations should be observed by qualified personnel. The Contractor is ultimately responsible for trench and site safety.

COLLAPSIBLE SOILS

Materials with collapse potential were observed in TP-01, TP-02, TP-04, TP-08, TP-09, TP- 10, and TP-11. In general these materials were observed in the upper 2 feet, with the exception of TP-01 where pinhole structure was observed as deep as 4 feet. These types of materials have the potential to produce differential settlements and pose risks to the steel pipe portions of the project. HDPE pipe areas will likely accommodate differential movement and therefore reduce the risk. Materials with collapse potential can typically be identified by their pinhole structure. These materials when found near the pipe alignment should be overexcavated and replaced. We recommend excavations in these areas be observed by a qualified geotechnical engineer during construction.

SUITIBILITY OF BACKFILL

Based on the data collected we believe the onsite materials are suitable for general backfill beyond the import/select backfill areas around the pipe. The medium plasticity materials (liquid limits greater than 35) have the potential to swell and should not be used as structural fill (i.e. beneath footings, pavements, or concrete flatwork). These materials can be used as general fill placed a minimum of 2 feet beyond any pipe works.

Trench backfill placed beneath structures, pavements or concrete flatwork should be compacted to at least 98 percent of the maximum density determined by ASTM D-698 (standard proctor) in accordance with APWA standards, unless more stringent requirements apply as outlined by the city, county or improvement district. Structural fill should be placed in maximum 8-inch loose lifts (prior to compaction). Lift thickness should be decreased to 6-inches in areas were lighter compaction equipment is used.

SOIL CORROSION POTENTIAL

In order to evaluate soil corrosion potential, we recommend that native soil samples be collected at a maximum spacing of 1000 feet from Stations 343+00 to 443+00. The native soil samples should be tested to measure concentrations of soluble chlorides, soluble sulfates, pH, and resistivity.

A recent study by Decker et al. (2008) on several exhumed 34 to 38 year old steel sections suggest critical zones for corrosion include a) the water table fluctuation zone and b) subsurface zones where two adjacent soil zones exhibit large differences in resistivity, pH, moisture, aeration, and cation/anion concentrations. Based on our understanding of the proposed construction, the steel pipe will be located within water table fluctuation zones. As such we recommend the designer address corrosion potential of steel elements in contact with native soils. Furthermore, we recommend the designer address deterioration of concrete elements due to sulfate attack in their design.

CONTROLLED LOW STRENGTH MATERIALS (CLSM)

Controlled Low Strength Material (CLSM) has been successfully used as backfill in pipeline trenches for many years. Traditionally, here in Utah, CLSM has consisted of fine aggregates, cement, and fly ash and has been batched at concrete manufacturing facilities and transported to the site in mixer trucks. Trench-side processes typically involve not only mixing CLSM materials at trench-side, but also using trench-side materials rather than exclusive fine aggregates. Cement and fly ash proportions in these processes are generally elevated, but these costs can often be offset by transportation costs associated with fine aggregates. An evaluation of trench-side processes and CSLM uses were outside our scope, however some general guidelines are summarized below.

• Trench-side CLSM processes and use of trench-side materials is probable; if utilized, native material soil types would need to be adequately defined in addition to a more thorough understanding of groundwater levels.

• Contractor shall submit mix designs which show the proportions and gradations of all materials proposed for use in CLSM. Contractor’s mix designs would need to address the full range of expected native soil types based on samples of the anticipated soils.

Additional site characterization (test pits and sampling) beyond ½ mile spacing would be needed to perform an assessment of trench-side processing.

LIMITATIONS

Recommendations contained in this report are based on a limited field study, and our understanding of the proposed construction plan. If the scope of the proposed construction plan changes from that described in this report, our firm should also be notified.

This report was prepared in accordance with the generally accepted standard of practice at the time the report was written. No warranty, expressed or implied, is made.

It is the Client's responsibility to see that all parties to the project including the Designer, Contractor, Subcontractors, etc. are made aware of this report in its entirety. The use of information contained in this report for bidding purposes should be done at the Contractor's option and risk.

REFERENCES

Decker, J.B., Rollins, K.M., and Ellsworth, J.C. (2008). "Corrosion Rate Evaluation and Prediction for Piles Based on Long-Term Field Performance." J. Geotechnical and Geoenvironmental Engineering. 134 (3).

Gerhart Cole (2013). “Geotechnical Study – Steinaker Service Canal Enclosure,” proposal to Bowen Collins and Associates.

Gerhart Cole (2013). “Geotechnical Study – Steinaker Service Canal Enclosure,” letter prepared for Bowen Collins and Associates