HomeMy WebLinkAbout09A 2021 Pavement Management – Hold Public Hearing, Order Project, Authorize Preparation of Plans and Specifications
Feasibility Report for
2021 Pavement Management Project
City of Cottage Grove, Minnesota
December 2020
Submitted by:
Bolton & Menk, Inc.
2035 County Rd D
Maplewood, MN 55109
P: 651-704-9970
F: 651-704-9971
December 2, 2020
Honorable Mayor and City Council
City of Cottage Grove
12800 Ravine Parkway South
Cottage Grove, MN 55016
RE: 2021 Pavement Management Project
BMI Project No. N14.122421
Honorable Mayor and City Council Members,
Enclosed for your review is the 2021 Pavement Management Project Feasibility Report. The project
scope includes street rehabilitation and utility repairs within the Pine Meadow, Sandy Hills, East
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Meadow Cliff neighborhoods and Jamaica Avenue from 80 Street to Indian Boulevard, as identified in
this report.
This report describes the improvements necessary within the project area. Cost estimates for the
proposed improvements are presented in the Report.
We would be happy to discuss this report at your convenience. Please contact me at 651-968-7674 if
you have any questions.
Sincerely,
BOLTON & MENK, INC.
Michael Boex, PE
Table of Contents
Introduction .......................................................................................................................... 1
Existing Conditions Residential ............................................................................................ 2
Streets ...................................................................................................................................... 2
Sanitary Sewer ......................................................................................................................... 3
Water Main .............................................................................................................................. 3
Storm Sewer ............................................................................................................................ 4
Existing Conditions Jamaica Avenue ..................................................................................... 4
Streets ...................................................................................................................................... 4
Sanitary Sewer ......................................................................................................................... 5
Water Main .............................................................................................................................. 6
Storm Sewer ............................................................................................................................ 6
Proposed Improvements Residential.................................................................................... 6
Streets ...................................................................................................................................... 6
Walkway .................................................................................................................................. 7
Sanitary Sewer ......................................................................................................................... 7
Water Main .............................................................................................................................. 7
Storm Sewer ............................................................................................................................ 7
Storm Water Quality ................................................................................................................ 8
Proposed Improvements Jamaica Avenue ............................................................................ 8
Streets ...................................................................................................................................... 8
Walkway .................................................................................................................................. 8
Sanitary Sewer ......................................................................................................................... 9
Water Main .............................................................................................................................. 9
Storm Sewer ............................................................................................................................ 9
Storm Water Quality ................................................................................................................ 9
Proposed Improvements Arbor Meadows Park .................................................................... 9
Proposed Improvements River Oaks Golf Course ................................................................ 10
Permits and Easements ........................................................................................................ 10
Estimated Costs ................................................................................................................... 10
Cost Allocation ....................................................................................................................... 10
Financing ................................................................................................................................ 12
Public Hearing ...................................................................................................................... 12
Project Schedule .................................................................................................................. 13
Conclusion and Recommendations ....................................................................................... 13
Prepared by: Bolton & Menk, Inc. Introduction
2021 Pavement Management 22421 Page i
Tables
Table 1: Residential Streets Existing Street Section ................................................................. 3
Table 2: Jamaica Avenue Existing Street Section ..................................................................... 4
Table 3: Ground Penetrating Radar ......................................................................................... 5
Table 4: Falling Weigh Deflectometer ..................................................................................... 5
Table 5: Estimated Cost Summary ......................................................................................... 10
Table 6: Deductions to Residential Property ......................................................................... 11
Table 7: Estimated Cost Allocation Per Policy ........................................................................ 11
Table 8: Estimated Cost Per Unit ........................................................................................... 12
Table 9: Estimated Cost Allocation Per Policy ........................................................................ 12
Table 10: Cost Per Unit Comparison ...................................................................................... 14
Appendix
Appendix A: Existing Pavement Condition Photos ................................................................. 15
Appendix B: Figures ............................................................................................................. 22
Appendix C: Cost Estimate Summary .................................................................................... 34
Appendix D: Preliminary Assessment Roll ............................................................................. 36
Appendix E: Pavement Cores Residential ........................................................................... 43
Appendix F: Geotechnical Report Jamaica Avenue.............................................................. 57
Figures
Figure 1: Location ................................................................................................................. 23
Figure 2: Year Constructed Residential ............................................................................... 24
Figure 3: Year Constructed Jamaica Avenue ....................................................................... 25
Figure 4: Pavement Condition Residential .......................................................................... 26
Figure 5: Street Improvements Residential ......................................................................... 27
Figure 6: Street Improvements Jamaica Avenue ................................................................. 28
Figure 7: Arbor Meadows Park Improvements ...................................................................... 29
Figure 8: River Oaks Golf Course Parking Lot Improvements .................................................. 30
Figure 9: Utility Improvements Residential ......................................................................... 31
Figure 10: Utility Improvements Jamaica Avenue ............................................................... 32
Figure 11: Assessable Parcels ................................................................................................ 33
Prepared by: Bolton & Menk, Inc. Introduction
2021 Pavement Management 22421 Page ii
Certification
Feasibility Report
for
2021 Pavement Management Report
City of Cottage Grove, Minnesota
I hereby certify that this plan, specification or report was
prepared by me or under my direct supervision, and that I
am a duly Licensed Professional Engineer under the laws of
the State of Minnesota.
By:
Michael Boex, PE
License No. 44576
Bolton & Menk, Inc.
Date: December 2, 2020
Prepared by: Bolton & Menk, Inc. Introduction
2021 Pavement Management 22421 Page iii
INTRODUCTION
The Pine Meadows, Sandy Hills, and East Meadow Cliff neighborhoods, along with Jamaica Avenue from
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80 Street to Indian Boulevard, have been identified as candidates for rehabilitation during the 2021
construction season as a part of the City of Cottage Grove's ongoing roadway rehabilitation program.
The City Council authorized preparation of this report to determine the feasibility of rehabilitating these
streets as a part of the 2021 Pavement Management Project.
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Pine Meadows 2, 4, and 5 Additions and Sandy Hills 7 and 8 Additions are located south of 85
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Street (including 85 between Johansen Avenue and CSAH 19), approximately 280 feet west of Keats
Avenue (CSAH 19), and east of Jewel Lane, as shown on Figure 1.
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The East Meadow Cliff neighborhood is located south of 80 Street and east of Jamaica Avenue, as
shown on Figure 1.
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Jamaica Avenue, between 80 Street and Indian Boulevard, is also included in this project and is shown
on Figure 1.
There are 11 residential streets within these neighborhoods totaling approximately 14,000 linear feet,
plus approximately 4,000 linear feet of an urban collector roadway.
The purpose of this report is to further evaluate the work required for this street rehabilitation project,
to provide an estimate of cost, and to establish a method of cost allocation or assessment in order to
determine the physical and economic feasibility.
This feasibility report examines the following street segments:
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Pine Meadows 2, 4 and 5 Additions
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1. 85 Street, from approximately 280 feet west of Keats Avenue to Johansen Avenue (9603
9998)
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2. Jorgensen Avenue, from 85 Street to Joliet Avenue (8506 8749)
3. Joliet Avenue, from Jorgensen Avenue to the end of the street (8536 8750)
4. Jorgensen Bay (8531 8571)
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Sandy Hills 7 and 8 Additions
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1. Johansen Avenue, from 85 Street to the end of the street
2. Jody Circle, west of Johansen Avenue (8502 8896)
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3. 87 Street, from Jody Circle to Johansen Avenue
4. Hillside Trail, from Jody Circle to Johansen Avenue, including the segment east of Johansen
Avenue
East Meadow Cliff Neighborhood
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1. Jefferey Avenue, from 80 Street to the cul-de-sac (8001 8305)
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2. Upper 81 Street, from Jeffery Avenue to approximately 285 feet west of Jefferey Avenue (9055
9071)
3. Jeffery Lane, west of Jefferey Avenue (8044 8228)
Jamaica Avenue
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1. Between Indian Boulevard and 80 Street
Prepared by: Bolton & Menk, Inc. Introduction
2021 Pavement Management 22421 Page 1
If the City decides to proceed with the proposed street and utility improvements as described in this
report, it is anticipated construction would begin in 2021 as shown in the detailed project schedule
found on page 13.
EXISTING CONDITIONS RESIDENTIAL
STREETS
The streets within these neighborhoods are urban-residential and are generally 32 feet wide (from face
of curb to face of curb) with D412 concrete curb and gutter; Johansen Avenue is 40-feet wide (from face
of curb to face of curb). The streets in the East Meadow Cliff neighborhood were constructed in 1991.
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The streets in the Pine Meadows 2, 4 and 5 Additions were constructed between 1992 and 1996.
The in-place pavement section of streets in the East Meadow Cliff and Pine Meadows neighborhoods
were designed to be approximately 3-inches of bituminous over 6-inches of aggregate base. The streets
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in Sandy Hills 7 and 8 Additions were constructed between 1997 and 1998. The in-place pavement
section of these streets was designed to be approximately 3.5-inches of bituminous over 6-inches of
aggregate base. Figure 2 depicts the age of the streets.
A visual inspection was performed in 2020 to evaluate the pavement surface conditions in the three
residential neighborhoods. The inspection determined the pavement conditions are considered
to distress. Figure 4 depicts the pavement condition within the
neighborhoods, and Appendix A contains some representative photos of the existing pavement
condition. In addition, there are sections of existing curb and gutter that have settled, cracked, or have
other defects that will require replacement.
Pothole repairs and skin patch overlays have been performed to keep the road in a drivable and
relatively smooth condition. A significant amount of street maintenance funds have been used or are
anticipated in upcoming maintenance cycles in these areas.
Past experience on recent projects has shown that the pavement cracking pattern on streets of this
general age and condition range extends well below the surface. In fact, the previous seal coat can help
mask the cracking in some instances.
It should be noted that the visual surface rating is a preliminary indicator of condition and potential
rehabilitation techniques; it should not solely dictate the maintenance or rehabilitation strategy. Factors
such as age, traffic projections, pavement strength, and pavement structure condition should also be
considered.
Coring of the pavement was performed to determine the thickness of the existing street section and
evaluate pavement condition. The core locations are shown on Figure 2 and photos of the pavement
cores can be seen in Appendix E. From the cores, it can be seen that the average section in the
neighborhoods consists of approximately 3.81 inches of bituminous over 6.75 inches of base, as shown
in Table 1. The thicker than expected bituminous is in part due to multiple seal coat applications or skin
patch overlays, as well as difficulty in evaluating bituminous depths from the stripped cores.
Prepared by: Bolton & Menk, Inc. Existing Conditions Residential
2021 Pavement Management 22421 Page 2
Table 1: Residential Streets Existing Street Section
Location
Bituminous Aggregate
No.
(in) Base (in)
Street Neighborhood
st2
East Meadow Cliff
C-1 Upper 81 Street 3.50 6.50
1
East Meadow Cliff
C-2 Jeffery Lane 3.75 8.25
2
East Meadow Cliff
C-3 Jeffery Avenue 4.00 8.75
1
East Meadow Cliff
C-4 Jeffery Avenue 4.00 7.50
nd
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Pine Meadows 2 Addition
C-05 85 Street 4.10 5.75
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th2
Pine Meadows 4 Addition
C-06 85 Street 4.50 3.75
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Pine Meadows 4 Addition
C-07 85 Street 3.50 7.25
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2
Pine Meadows 5 Addition, Phase 1
C-08 Jorgensen Avenue 3.80 9.25
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Pine Meadows 5 Addition, Phase 1
C-09 Joliet Avenue 3.10 8.25
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Pine Meadows 5 Addition, Phase 2
C-10 Jorgensen Avenue 3.60 2.50
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1
Pine Meadows 5 Addition, Phase 2
C-11 Jorgensen Avenue 4.00 4.50
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1
Sandy Hills 7 Addition
C-12 Jody Circle 4.40 5.25
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1
Sandy Hills 7 Addition
C-13 Johansen Avenue 4.00 9.00
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1
Sandy Hills 8 Addition
C-14 Hillside Trail 3.00 7.25
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1
Sandy Hills 8 Addition
C-15 Jody Circle 3.90 7.50
Average 3.81 6.75
1. Stripping present (Varying severity)
2. Severe stripping present (Core was broken upon extraction)
Thirteen of the fifteen cores within the residential neighborhoods displayed some degradation due to
asphalt stripping. Stripping is generally described as the separation of aggregate from the asphalt due to
moisture. The stripping found degrades the strength and durability of the pavement. Four of the cores
were noted as broken, meaning the stripping was severe enough that the bituminous fell apart as the
core was extracted. The locations of stripping generally coincided with areas where Public Works has
performed extensive maintenance via skin patch overlays and patching, whereas areas with slight
stripping may not be visible at the pavement surface.
Due to the granular subgrade soils and good aggregate base, the pavement structure as a whole is
typically structurally sound. Therefore, the issue facing the City is typically functional and not structural
meaning the recurring maintenance issues are due to the stripped pavement material raveling and
breaking apart.
SANITARY SEWER
The sanitary sewer system within the residential neighborhoods consists primarily of 8-inch diameter
polyvinyl chloride pipe (PVC). The existing sanitary sewer has been televised to evaluate pipe condition.
The televising reports show that the pipe is generally in good condition. Miscellaneous structure repairs
including patching and other repairs were noted during the inspections.
WATER MAIN
The water mains within the residential neighborhoods are 6 to 18-inch diameter ductile iron pipe (DIP),
which were installed in conjunction with the development of the neighborhoods.
Prepared by: Bolton & Menk, Inc. Existing Conditions Residential
2021 Pavement Management 22421 Page 3
The water mains are believed to be in good condition. However, projects of similar eras have had
instances of excessive bolt corrosion on valves and it is possible the valves in this project area may be in
a similar condition. Therefore, some select valves will be checked for corrosion prior to street work
occurring. Additionally, there are expected to be some valves which are not operational and will need to
be addressed with the project. The valves will be operated and evaluated by Public Works prior to the
start of the project.
STORM SEWER
The existing storm sewer has been televised to determine pipe condition and necessary repairs. In
addition, storm structures were also inspected. The televising reports show that the storm sewer mains
are generally in good condition. However, some problems encountered in the existing storm sewer were
cracked or broken pipes. Most structures were identified as in good condition with some miscellaneous
structure patching, and other repairs noted during the inspections.
EXISTING CONDITIONS JAMAICA AVENUE
STREETS
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Jamaica Avenue, between 80 Street and Indian Boulevard, is a four-lane divided urban roadway
consisting of B618 concrete curb and gutter, 14-foot lanes and a grass median. In 1980, a 74-foot wide
section was constructed with a 6-inch aggregate base and a 24-foot bituminous mat, consisting of two
1.5-inch lifts, on the west side. In 1981, a 24-foot bituminous mat, consisting of two 1.5-inch lifts, was
constructed on the east side of the original 74-foot aggregate base section. In 1993, the existing south
bound and northbound lanes had a 1.5-inch bituminous overlay on the existing 3-inch bituminous mat.
As part of this 1993 project, the lanes were constructed to a 28-foot (from face of curb to face of curb)
street width for each direction of traffic, with B618 concrete curb and gutter, a grass median, and
concrete sidewalk. The in-place pavement section of Jamaica Avenue was designed to be 4.5-inches of
bituminous over 6-inches of aggregate base. Figure 3 depicts the age of the streets.
Coring of the pavement was performed to determine the thickness of the existing street section and
evaluate pavement condition. The core locations are shown on Figure 3 and photos of the pavement
cores can be seen in Appendix F. From the cores, it can be seen that the average section along Jamaica
Avenue consists of approximately 5.5-inches of bituminous over 7-inches of base, as shown in Table 2.
The thicker than expected bituminous is in part due to multiple seal coat applications or thin overlays.
The cores show slight to severe stripping occurring in various depths of the pavement, depending on the
location. All cores from Jamaica Avenue displayed some degradation due to stripping. The stripping
found degrades the strength and durability of the pavement.
Table 2: Jamaica Avenue Existing Street Section
Bituminous Aggregate Base
No. Location
(in) (in)
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B-5 Between 80 Street and 75 Street 6.00 11.00
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B-6 Between 75 Street and Indian Boulevard 5.50 5.00
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B-7 South of 75 Street 5.00 5.00
Average 5.50 7.00
1. Stripping present (Varying severity)
Prepared by: Bolton & Menk, Inc. Existing Conditions Jamaica Avenue
2021 Pavement Management 22421 Page 4
Additional testing was performed on Jamaica Avenue in an effort to better identify the properties of the
roadway. Therefore, ground penetrating radar (GPR) and falling weight deflectometer (FWD) testing was
performed on all four lanes.
Ground penetrating radar is a non-intrusive procedure that produces an image of the underground
materials by sending and interpreting electromagnetic waves. GPR was used to supplement the cores
and obtain more data points regarding pavement and aggregate base thickness. The pavement section
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properties, between 80 Street and Indian Boulevard, obtained from the GPR is presented below.
Table 3: Ground Penetrating Radar
SB Outside Lane SB Inside Lane NB Inside Lane NB Outside Lane
Layer
Average Average Average
Average
CV CV CV
CV
(in) (in) (in) (in)
5.2 8%
BP 5.3 13% 5.2 13% 5.7 8%
5.3 22%
Base 5.9 20% 5.2 20% 7.7 25%
10.6 11%
Total 11.2 12% 10.4 11% 13.4 16%
*BP = Bituminous Pavement; Base = Aggregate Base; Total = BP and Base; CV = Coefficient of Variation
The falling weight deflectometer is a non-destructive process used to evaluate pavement structural
condition by providing an in-situ characterization of the pavement layer stiffness. The FWD applies
dynamic loads to a pavement surface, simulating the magnitude and duration of a single wheel load. The
downward movement (vertical deflection) of the pavement at various distances from the loading plate
are measured with various sensors. These measurements help determine the overall pavement load
rating, pavement layer characteristics and material properties (modulus), and subgrade strength
characteristics (in-situ R-Value). The R-Value is representative of the ability of a soil to resist lateral
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spreading due to an applied vertical load from traffic. The 15 percentile R-Values and GE values,
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between 80 Street and Indian Boulevard, from the FWD are presented below.
Table 4: Falling Weigh Deflectometer
From To Lane R-Value GE
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23.7 27.4
80 Street 75 Street NB
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30.5 26.2
75 Street Indian Boulevard NB
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36.9 22.0
Indian Boulevard 75 Street SB
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24.8 27.9
75 Street 80 Street SB
25.8
Average 28.9
Appendix F contains the complete Jamaica Avenue geotechnical report completed in July 2020. This
report analyzes the pavement of Jamaica Avenue from Indian Boulevard to the Highway 61/Jamaica
Avenue roundabout south of East Point Douglas Road.
SANITARY SEWER
The sanitary sewer system along Jamaica Avenue connects adjacent neighborhoods east and west of
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Jamaica Avenue. The sanitary sewer north of 80 Street that connects to the neighborhood east of
Jamaica Avenue has been televised to determine pipe condition and necessary repairs. The televising
reports show that the pipe is generally in good condition and no repairs are needed.
Prepared by: Bolton & Menk, Inc. Existing Conditions Jamaica Avenue
2021 Pavement Management 22421 Page 5
WATER MAIN
There are two locations where water main crosses Jamaica Avenue to connect adjacent neighborhoods,
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once at Indian Boulevard and once at 75 Street. The water main on the west side of Jamaica Avenue at
Indian Boulevard is a 12-inch diameter DIP and was installed in 1979 in conjunction with the
development of the neighborhood west of Jamaica Avenue. In 1980 this water main was connected to
and installed across Jamaica Avenue in conjunction with the development of the neighborhood to the
east of Jamaica Avenue.
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The water main on the west side of Jamaica Avenue at 75 Street is a 12-inch diameter DIP and was
installed in 1974 in conjunction with the development of the neighborhood west of Jamaica Avenue. In
1979 this water main was connected to and installed across Jamaica Avenue in conjunction with the
development of the neighborhood to the east of Jamaica Avenue.
The water mains are believed to be in good condition. However, due to the age of the water main, there
are expected to be some valves which are not operational and will need to be addressed with the
project. The valves will be operated and evaluated by Public Works prior to the start of the project.
STORM SEWER
The existing storm sewer has been televised to determine pipe condition and necessary repairs. In
addition, storm structures were also inspected. The televising reports show that the storm sewer mains
are generally in good condition. However, some problems encountered in the existing storm sewer were
cracked or broken pipes. Most structures were identified as in good condition with some miscellaneous
structure patching, lining, and other repairs noted during the inspections.
PROPOSED IMPROVEMENTS RESIDENTIAL
STREETS
Due to the age of pavements in the residential neighborhoods (22-29 years old), the observed depth and
extent of the asphalt stripping in the cores, extent of previous City maintenance, and past City
experience with streets of this age and condition, a mill-overlay is not recommended at this time for the
Pine Meadows, Sandy Hills, and East Meadow Cliff neighborhoods.
The risks typical of all mill-overlay projects, i.e. reflective cracking, and the associated maintenance
required were evaluated to determine acceptable risk levels. Past projects have shown that stripping of
the pavement can extend well below the surface of the pavement, making complete removal of the
stripped portions unfeasible. In those cases, the remaining pavement posed risk for excessive volume of
cracking or raveling in the base course.
Due to the types of distress present in the existing pavement, the anticipated acceleration of
deterioration due to asphalt stripping, and risks associated with a mill-overlay at this age, the residential
streets within the Pine Meadows, Sandy Hill, and East Meadow Cliff neighborhoods are proposed to
undergo a full pavement removal and replacement with 3.5-inches of new pavement. The wear course is
proposed to be virgin mix, excluding the use of recycled asphalt pavement (RAP).
The concrete curb and gutter in all three neighborhoods are proposed to undergo spot replacement, as
shown in Figure 5. The curb in poor condition will be evaluated for removal just prior to construction.
Preliminary estimates indicate that approximately 17% will need to be removed and replaced in the Pine
Meadows and Rolling Hills neighborhoods and 18% in the East Meadow Cliff neighborhood. The
percentage of curb is not necessarily evenly distributed and there may be some long sections of curb
Prepared by: Bolton & Menk, Inc. Proposed Improvements Residential
2021 Pavement Management 22421 Page 6
replacement. Where conditions are favorable, the goal is that the concrete curb and gutter last two
pavement lifecycles.
In locations where curb is removed and replaced in front of driveways, impacted concrete or bituminous
driveways will be patched the entire width with in-kind materials as a part of the street rehabilitation
process. In areas of spot curb replacement, this patch typically extends a few feet behind the curb.
Restoration is anticipated to consist of screened Loam Topsoil Borrow with seed and hydromulch.
Traffic signs are proposed to be replaced as a part of this project to meet federal retro reflectivity
requirements. In addition, signs will be evaluated for conformance to the adopted City sign policy and
signs will be removed or supplemented as required.
The existing streetlight system has received routine maintenance and does not have any major areas of
concern. The existing four feed point cabinets in the residential neighborhoods are beyond their useful
life and should be replaced as part of this project. Existing poles, direct-bury wire, and handholes will
remain in place. Should the spot curb removal process impact the existing direct-buy wiring, spot repairs
will be completed as necessary.
WALKWAY
Costs have been included in this report to update all pedestrian ramps to the current Americans with
Disabilities Act (ADA) standards. All pedestrian ramps will be evaluated and reconstructed to compliant
pedestrian ramps; this may include removing some segments of existing sidewalk to meet the required
landings and grades. Spot sidewalk removal and replacement is also proposed to correct damaged curb
panels along Johansen Avenue.
SANITARY SEWER
Utility improvements are shown in Figure 9.
The sanitary sewer manhole castings will be salvaged and reinstalled. The existing concrete adjusting
rings will be replaced with new high-density polyethylene (HDPE) adjusting rings to conform to current
City standards. Miscellaneous structure repairs such as patching or replacing a top slab will be
performed as needed.
WATER MAIN
It is proposed that broken valve top sections be removed and replaced as a part of this project. It is
anticipated that a small sample of valves be dug up in each neighborhood and checked for bolt corrosion
in the spring. Any corroded bolts would be replaced if necessary, and additional valves with like
conditions could be dug up and checked if warranted. As a part of this process, the valve box would be
replaced in conjunction with the work. Also, it is proposed to extend the hydrant barrel on any hydrant
requiring adjustment. Finally, hydrants will be reconditioned by sandblasting and painting, and concrete
hydrant access pads are proposed to be constructed in accordance with current City standards.
STORM SEWER
Generally speaking, the intent of this project is to rehabilitate the streets and not change existing
drainage patterns. In-line repairs are recommended to address cracks and offset joints. Structures in
poor condition will be replaced to conform to current City standards. Adjustment rings for manholes and
catch basins will be replaced with HDPE rings. The existing castings will be salvaged and reinstalled
unless they are damaged or do not meet current City standards. Miscellaneous structure patching,
lining, and other repairs will be performed as needed.
Prepared by: Bolton & Menk, Inc. Proposed Improvements Residential
2021 Pavement Management 22421 Page 7
Public Works staff provided input on areas with historic drainage concerns. No major flooding or
drainage issues were noted; therefore, only minor curb grade modifications are proposed to facilitate
drainage.
STORM WATER QUALITY
Storm water quality improvements are not required in this neighborhood due to no increase of
impervious surfacing.
PROPOSED IMPROVEMENTS JAMAICA AVENUE
STREETS
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Due to the condition of the pavement along Jamaica Avenue between Indian Boulevard and 80 Street,
the observed depth and extent of the asphalt stripping in the cores, results of the GPR and FWD, extent
of previous City maintenance and past City experience with streets of this age and condition, a full-
depth pavement replacement is recommended at this time.
Due to the types of distress present in the existing pavement, the anticipated acceleration of
deterioration due to asphalt stripping, and risks associated with a mill-overlay at this age, Jamaica
Avenue is proposed to undergo a full pavement removal and replacement with 5.5-inches of new
pavement. The wear course is proposed to be virgin mix, excluding the use of recycled asphalt pavement
(RAP).
The concrete curb and gutter along Jamaica Avenue is proposed to undergo spot replacement, as shown
in Figure 6. The curb in poor condition will be evaluated for removal just prior to construction.
Preliminary estimates indicate that approximately 11% will need to be removed and replaced. The
percentage of curb is not necessarily evenly distributed and there may be some long sections of curb
replacement. Where conditions are favorable, the goal is that the concrete curb and gutter last two
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pavement lifecycles. In order to accommodate a future signal system at 80 Street, both north and
south-bound Jamaica Avenue approaches will need geometric improvements to facilitate through
traffic, at which time a full reconstruction should be coordinated. Due to the necessary geometric
improvements, full curb replacement and the signal would be installed in conjunction with a future
Jamaica Avenue project.
Restoration is anticipated to consist of screened Loam Topsoil Borrow with seed and hydromulch.
Traffic signs are proposed to be replaced as a part of this project to meet federal retro reflectivity
requirements. In addition, signs will be evaluated for conformance to the adopted City sign policy and
signs will be removed or supplemented as required.
The existing streetlight system has received routine maintenance and does not have any major areas of
concern. Existing poles, direct-bury wire, and handholes will remain in place. Should the spot curb
removal process impact the existing direct-buy wiring, spot repairs will be completed, as necessary.
WALKWAY
Costs have been included in this report to update all pedestrian ramps to the current Americans with
Disabilities Act (ADA) standards. All pedestrian ramps will be evaluated and reconstructed to compliant
pedestrian ramps; this may include removing some segments of existing sidewalk to meet the required
landings and grades. Several pedestrian ramps along Jamaica Avenue have been recently reconstructed
in past pavement management projects and will not need to be reconstructed as part of this project.
Prepared by: Bolton & Menk, Inc. Proposed Improvements Jamaica Avenue
2021 Pavement Management 22421 Page 8
Spot sidewalk removal and replacement is also proposed to correct for damaged curb panels along both
sides of Jamaica Avenue.
SANITARY SEWER
Utility improvements are shown in Figure 10.
The sanitary sewer manhole castings will be salvaged and reinstalled. The existing concrete adjusting
rings will be replaced with new high-density polyethylene (HDPE) adjusting rings to conform to current
City standards.
WATER MAIN
The valve boxes will be adjusted to final grades and any broken valve top sections will be removed and
replaced as part of this project.
STORM SEWER
Generally speaking, the intent of this project is to rehabilitate the streets and not change existing
drainage patterns. In-line repairs are recommended to address cracks, while pipes that had holes in
them are recommended to be removed and replaced. Structures in poor condition will be replaced to
conform to current City standards. Adjustment rings for manholes and catch basins will be replaced with
HDPE rings. The existing castings will be salvaged and reinstalled unless they are damaged or do not
meet current City standards. Miscellaneous structure patching and other repairs will be performed as
needed.
Public Works staff provided input on areas with historic drainage concerns. No major flooding or
drainage issues were noted; therefore, only minor curb grade modifications are proposed to facilitate
drainage.
STORM WATER QUALITY
Storm water quality improvements are not required in this neighborhood due to no increase of
impervious surfacing.
PROPOSED IMPROVEMENTS ARBOR MEADOWS PARK
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Arbor Meadows park is located south of 85 Street, east of Johansen Avenue, west of Joliet Avenue, and
north of Hillside Trail. Similar to past pavement management projects, when a neighborhood undergoes
a pavement management project, the neighborhood park is also evaluated for site improvements.
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The parking lot for Arbor Meadows Park was constructed in 1997 along with the Sandy Hills 7 Addition
and consists of approximately 3-inches of bituminous over 6-inches of aggregate base. The existing trail
that connects the Arbor Meadows parking lot to Jorgensen Avenue, was constructed in 2016 with 6-
inches of gravel and 3-inches of bituminous. As part of the 2021 project the parking lot is proposed to
have a full pavement replacement with spot curb and gutter replacement. The existing pedestrian ramp
will be reconstructed to meet ADA compliance. A new trail is proposed to connect to the existing trail
near the playground, follow the perimeter of the park, and connect to the existing trail west of
Jorgensen Avenue, as shown in Figure 7. This new trail would also connect to the two existing street
connections at Johansen Avenue and Hillside Trail. In addition to these improvements, it is proposed to
install a water irrigation service for future use. Bidding alternatives will be evaluated during design for
additional improvements.
Prepared by: Bolton & Menk, Inc. Proposed Improvements Arbor Meadows Park
2021 Pavement Management 22421 Page 9
PROPOSED IMPROVEMENTS RIVER OAKS GOLF COURSE
River Oaks Golf Course is a City-owned 18-hole scenic golf course located on Highway 61. In late 2020
the club house underwent construction with a kitchen addition to the northwest corner of the
clubhouse. As part of the pavement management project, the parking lot is proposed to receive a full
pavement replacement with spot curb and gutter replacement. As part of these improvements, the
existing pedestrian ramps will be reconstructed to meet ADA compliance, new parking lot lighting and
islands will be installed, as shown in Figure 8. We will continue to work with Cottage Grove staff to
evaluate additional golf course site improvements during the final design phase of the project as
budgetary conditions allow.
PERMITS AND EASEMENTS
A Phase II General Storm Water Permit from the MPCA is anticipated to be required for the project
because disturbance and restoration will likely exceed one acre.
All streets in the project area are located within the South Washington Watershed District (SWWD),
however, because there will be no disturbance to the existing subgrade a permit is not required.
No additional drainage and utility easements are anticipated in the neighborhoods; however, this will be
evaluated during the final design phase of the project.
ESTIMATED COSTS
Cost estimates for the improvements have been prepared and are included in Appendix C. All costs for
items to be constructed are based on anticipated unit prices for the 2021 construction season. All costs
include a twenty-five percent allowance for indirect costs associated with the project (engineering,
administrative, financing, and legal) as well as a ten percent contingency. No costs are included for
capitalized interest during the construction period or before assessments are levied. The following is an
overall summary of the estimated costs:
Table 5: Estimated Cost Summary
Location Estimated Project Cost*
Pine Meadows, Sandy Hills & East Meadow Cliff Neighborhoods $2,423,817.35
Jamaica Avenue $1,442,819.13
Arbor Meadows Park $291,142.50
River Oaks Golf Course $522,119.81
Total $4,679,898.79
*Costs presented include 10% contingency + 25% indirect costs
COST ALLOCATION
Assessments for this project will be based upon the "Infrastructure Maintenance Task Force Special
Assessment Policy for Public Improvements," dated September 30, 2005, Revised August 8, 2012. All
adjacent benefiting properties are proposed to be assessed. Per the Urban Residential policy, 45% of the
project cost for both surface and subsurface improvements would be assigned to each individual
residential lot on a unit basis. The intent of the City's policy is to treat all properties within a residential
Prepared by: Bolton & Menk, Inc. Proposed Improvements River Oaks Golf Course
2021 Pavement Management 22421 Page 10
development as similar individual units regardless of lot frontage. The amount assessed is based on the
City standard street section even if the width is greater. City funds would be responsible for the
remaining 55% of the project costs.
Per the policy, 100% of the project costs adjacent to the property are assessedto City-owned property.
In areas where residential property was opposite City property, half of the street width was assigned to
the residential area and the other half to the City. The estimated project assessments are as follows:
Residential Land Use:
Infrastructure costs adjacent to City property or other land uses are removed from the neighborhoods
to determine the residential cost contribution. The policy also states that all urban/residential lots on
urban/residential streets shall be assessed based on the city standard street section even if the width is
greater.
Table 6: Deductions to Residential Property
Estimated
Location City Property Street Width Assessment
Deduct
Pine Meadows, Sandy Hills & East Meadow Cliff $9,545.39 $43,290.84 $52,836.23
Jamaica Avenue $1,442,819.13* $0.00 $1,442,819.13
Arbor Meadows Park $291,142.50 $0.00 $291,142.50
River Oaks Golf Course $522,119.81 $0.00 $522,119.81
Total $2,265,626.83 $43,290.84 $2,308,917.67
* Since no residential property that abuts Jamaica Ave has direct access, there are no assessable parcels and the
City therefore covers the cost.
Per the IMTF policy, urban residential lots on urban/residential streets within or outside the MUSA, 45%
of the project costs for both surface and sub-surface assessments will be assessed.
Table 7: Estimated Cost Allocation Per Policy
Estimated Residential
Estimated Residential
Location Assessment Assessed Amount
Project Cost Adjusted Cost
Deduct (45% of Total)
Pine Meadows, Sandy Hills &
$2,423,817.35 $52,836.23 $2,370,981.12 $1,066,941.50
East Meadow Cliff
Jamaica Avenue $1,442,819.13 $1,442,819.13 $0.00 $0.00
Arbor Meadows Park $291,142.50 $291,142.50 $0.00 $0.00
River Oaks Golf Course $522,119.81 $522,119.81 $0.00 $0.00
Total $4,679,898.79 $2,308,917.67 $2,370,981.12 $1,066,941.50
Prepared by: Bolton & Menk, Inc. Estimated Costs
2021 Pavement Management 22421 Page 11
Since all three neighborhoods have the same construction method and similar expected curb removal, a
single assessment was determined by the total assessable RBLE units and total assessed amount for all
three neighborhoods. Based on the table below, the total single-family residential assessment is
$4,167.74 per unit in the Pine Meadows, Sandy Hills Neighborhoods and East Meadow Cliff
Neighborhood.
Table 8: Estimated Cost Per Unit
Assessed Cost Special Benefit
Assessable Assessed Amount
Location Per RBLE Unit Appraisal
RBLE Units (45% of Total)
Per Policy
Pine Meadows, Sandy Hills &
$5,600 - $7,600
256 $1,066,941.50 $4,167.74
East Meadow Cliff
When the calculated assessment exceeds the special benefit appraisal, the single-family assessments
will be proposed to be capped at the amount of the special benefit appraisal. If needed, City funds will
cover the difference between the calculated assessment and the benefit appraisal. The benefit appraisal
was completed in October 2020 and resulted in a change of benefit from $5,600 to $7,600, which is
greater than the policy calculation, therefore the policy calculation will determine the proposed
assessment.
Religious Institution Use:
th
Crossroads Church, located at the northwest corner of Jamaica Avenue and 80 Street, is accessed from
th
Ivystone Avenue. In 2016, when 80 Street was reconstructed, a benefit appraisal was completed for
th
Crossroads Church and no benefit was found because it is not directly accessed from 80 Street. Due to
a similar circumstance of no direct access from Jamaica Avenue, Crossroads Church will not be assessed.
Summary:
The IMTF policy therefore allocates costs in the following manner:
Table 9: Estimated Cost Allocation Per Policy
Residential Assessed Amount Estimated Project
Location Other Funds*
(45% of Total) Cost**
Pine Meadows, Sandy Hills &
$1,066,941.50 $1,356,875.85 $2,423,817.35
East Meadow Cliff
Jamaica Avenue $0.00 $1,442,819.13 $1,442,819.13
Arbor Meadows Park $0.00 $291,142.50 $291,142.50
River Oaks Golf Course $0.00 $522,119.81 $522,119.81
Total $1,066,941.50 $3,612,957.29 $4,679,898.79
*See Appendix C for Fund Breakout
** Total Project Cost (10% contingency + 25% Indirect)
Prepared by: Bolton & Menk, Inc. Estimated Costs
2021 Pavement Management 22421 Page 12
FINANCING
Assessments are proposed to be levied based on the City's current assessment policy. The remainder of
the project would be financed through a combination of City funds such as the General Tax Levy and
Utility and Enterprise funds for items such as storm sewer and street lighting improvements. Figure 11
depicts the assessable parcels for the project.
PUBLIC HEARING
Because the properties within the project area benefit from the proposed improvements, and the
project will be partially funded through assessment, it will be necessary for the City to hold a public
improvement hearing to receive comment on the proposed project and to determine further action to
be taken.
PROJECT SCHEDULE
Below is the proposed schedule assuming starting construction in 2021:
08/19/2020 Council Orders Feasibility Report
12/02/2020 Council Receives and Approves Feasibility Report
Council Sets a Public Improvement Hearing Date
12/10/2020 Hold Neighborhood Meeting
01/06/2020 Council Holds Public Improvement Hearing
Council Orders the Preparation of the Plans and Specifications
03/03/2021 Council Approves the Plans and Specifications
03/25/2021 Project Bid Date
04/07/2021 Contract Award
Spring 2021 Begin Construction
September 2021 Complete Construction
September 2021 Council Sets Assessment Hearing Date
October 2021 Council Holds Assessment Hearing
CONCLUSION AND RECOMMENDATIONS
It is recommended that this report be used as a guide for the layout, design, and cost allocation for the
public improvements to be made as part of the 2021 Pavement Management Project. It is further
recommended that the owners of properties within the project limits be notified of the proposed
improvements in order to provide comment.
To determine project feasibility, a comparison was made between the costs estimated herein and the
costs experienced for other similar projects within the City. These comparisons, on a per linear foot
construction cost basis (no indirect project costs), are shown in the following table:
Prepared by: Bolton & Menk, Inc. Public Hearing
2021 Pavement Management 22421 Page 13
Table 10: Cost Per Unit Comparison
2021 Pavement Management Project (Estimated Costs per Linear Foot)
ndthththth
Pine Meadows 2, 4, and 5 Additions and Sandy Hills 7 and 8 Additions
$115.76 / LF
Pavement Replacement Area & Spot Curb
East Meadow Cliff Pavement Replacement Area & Spot Curb $115.40 / LF
2017 Pavement Management Project (Bid Results)
rdthth
Rolling Hills 3, 6, and 7 Additions Pavement Replacement Area & Spot Curb $102.71 / LF
Jamaica Ridge Additions Pavement Replacement Area & Spot Curb $90.65 / LF
2016 Pavement Management Project (Bid Results)
District F3/F5 Pavement Replacement Area & Spot Curb $97.06 / LF
From the tabulation above, it is indicated that the cost to rehabilitate in the residential areas are like
past projects of similar scope. The increase depicted is partially due to rises in construction and material
costs.
Financial responsibilities have been determined based on estimated project costs as well as adopted City
policy. Funding sources consist of assessments to benefitted properties and use of existing designated
City funds.
Based on the information contained herein, it can be concluded that the construction of utility and
street improvements is feasible. The deteriorated condition of the pavement, stable condition of the
subgrade, and condition of the concrete curb and gutter suggest that similar rehabilitation be performed
in all three neighborhoods, as well as Jamaica Avenue. The improvements are cost effective as they
utilize the existing subgrade and keep existing curb wherever possible.
From an engineering standpoint, this project is feasible, necessary, cost effective, and can best be
accomplished by letting competitive bids for the work under one contract in order to complete the work
in an orderly and efficient manner.
Prepared by: Bolton & Menk, Inc. Conclusion and Recommendations
2021 Pavement Management 22421 Page 14
Appendix A: Existing Pavement Condition
Photos
City of Cottage Grove, Minnesota Appendix A: Existing Pavement Condition Photos
2021 Pavement Management Page 15
Pine Meadow Neighborhood
th
Approximate Location: 9821 85 Street
Temporary skin patch overlay across entire width of road performed in 2010. Additional
patching has since occurred, and original distresses have reflected through.
Pine Meadow Neighborhood
th
Approximate Location: 9998 85 Street
Reflective cracking through temporary skin patch overlay.
City of Cottage Grove, Minnesota Appendix A: Existing Pavement Condition Photos
2021 Pavement Management Page 16
Pine Meadow Neighborhood
Approximate Location: 8732 Joliet Avenue
Fatigue/small block cracking adjacent to an open transverse joint.
Pine Meadow Neighborhood
Approximate Location: 8719 Jorgensen Avenue
Curb and gutter settlement and resultant poor drainage evident; numerous street
patches present.
City of Cottage Grove, Minnesota Appendix A: Existing Pavement Condition Photos
2021 Pavement Management Page 17
Sandy Hills Neighborhood
Approximate Location: 8689 Johansen Avenue
Thin overlay along the curb line to address asphalt stripping, numerous patch attempts
and crack sealing present.
Sandy Hills Neighborhood
Approximate Location: 9553 Hillside Trail
Large block cracking typical throughout.
City of Cottage Grove, Minnesota Appendix A: Existing Pavement Condition Photos
2021 Pavement Management Page 18
Sandy Hills Neighborhood
Approximate Location: 9589 Hillside Trail
Asphalt stripping along the curb line; previous patching attempts evident.
East Meadow Cliff Neighborhood
Approximate Location: 8279 Jeffery Avenue
This photo was taken in 2018 and depicts fatigue cracking, previous route and seal of
cul-de-sac. This area has since been patched but the underlying condition is still present.
City of Cottage Grove, Minnesota Appendix A: Existing Pavement Condition Photos
2021 Pavement Management Page 19
East Meadow Cliff Neighborhood
Approximate Location: 8236 Jeffery Avenue South
This photo was taken in 2018 and depicts severe asphalt stripping and previous
attempts to patch. This area has since been patched but the underlying condition is still
present.
East Meadow Cliff Neighborhood
Approximate Location: 8241 Jeffery Lane
Functional concrete curb and gutter, although exposed aggregate surface appearance.
City of Cottage Grove, Minnesota Appendix A: Existing Pavement Condition Photos
2021 Pavement Management Page 20
East Meadow Cliff Neighborhood
Approximate Location: 8033 Jeffery Lane
This photo was taken in 2018 and depicts typical block cracking and pavement fatigue in
the neighborhood.
East Meadow Cliff Neighborhood
st
Approximate Location: 9063 Upper 81 Street
Asphalt stripping and associated patching attempts.
City of Cottage Grove, Minnesota Appendix A: Existing Pavement Condition Photos
2021 Pavement Management Page 21
Appendix B: Figures
City of Cottage Grove, Minnesota Appendix B: Figures
2021 Pavement Management Page 22
Appendix C: Cost Estimate Summary
City of Cottage Grove, Minnesota Appendix C: Cost Estimate Summary
2021 Pavement Management Page 34
Appendix D: Preliminary Assessment Roll
City of Cottage Grove, Minnesota Appendix D: Preliminary Assessment Roll
2021 Pavement Management Page 36
Appendix E: Pavement Cores Residential
City of Cottage Grove, Minnesota Appendix E: Pavement Cores Residential
2021 Pavement Management Page 43
Coring Location C-1
Coring Location C-2
Bituminous and Aggregate Base Coring Results
Cottage Grove 2018 PMP
Cottage Grove, MN
NTI Project No. 17.IGH03784.000
Coring Location C-3
*
Coring Location C-4
*
NTIs Field Technicians disturbed the aggregate base beneath the road with the coring drill barrel. The
displaced materials were removed from the hole and the core prior to these pictures. This incident accounts for
the discrepancy between the hole and core dimensions.
Appendix F: Geotechnical Report Jamaica
Avenue
City of Cottage Grove, Minnesota Appendix F: Geotechnical Report Jamaica Avenue
2021 Pavement Management Page 57
REPORT OF GEOTECHNICAL
CONSULTANTS
·ENVIRONMENTAL
EXPLORATION
·GEOTECHNICAL
·MATERIALS
·FORENSICS
Jamaica AvenueImprovements
BetweenHighway 61 and Indian Blvd
Cottage Grove,Minnesota
AETReport No.28-20309
Date:
July 2, 2020
Prepared for:
Bolton & Menk, Inc.
2035 County Road D East
Maplewood, Mn 55109
www.amengtest.com
CONSULTANTS
•ENVIRONMENTAL
•GEOTECHNICAL
•MATERIALS
•FORENSICS
July 2, 2020
Bolton & Menk, Inc.
2035 County Road D East
Maplewood, Mn 55109
Attn: Mike Boex, PE
Michael.boex@bolton-menk.com
RE: Geotechnical Exploration Data Report
Jamaica Avenue Improvements
Cottage Grove, Minnesota
AET Project No. 28-20309
Dear Mr. Boex:
American Engineering Testing, Inc. (AET) is pleased to presentthe results of our subsurface
exploration program for the referenced project in Cottage Grove, Minnesota. These services were
performed according to our proposal to you datedMay 6, 2020.
We are submitting one electronic copy of the report to you. Papercopies can be provided upon
request. Please contact me if you have any questions about the report.
Sincerely,
American Engineering Testing, Inc.
Jacob O. Michalowski, P.E.
Senior Engineer
Phone: (651) 283-2481
jmichalowski@amengtest.com
Page i
550 Cleveland Avenue North | Saint Paul, MN 55114
Phone (651) 659-9001 | (800) 972-6364 | Fax (651) 659-1379 | www.amengtest.com | AA/EEO
This document shall not be reproduced, except in full, without written approval from American Engineering Testing, Inc.
Report of Geotechnical Exploration
Jamaica Avenue Improvements - Cottage Grove, MNAMERICAN
July 2, 2020ENGINEERING
AET Report No. 28-20309TESTING, INC.
SIGNATURE PAGE
Prepared for:Prepared by:
Bolton & Menk, Inc. American Engineering Testing, Inc.
2035 County Road D East 550 Cleveland Avenue North
Maplewood, Mn 55109 St. Paul, Minnesota 55114
(651)659-9001/www.amengtest.com
Attn: Mike Boex, PE
M
ichael.boex@bolton-menk.com
Authored by: Reviewed by:
Thomas Evans, P.E.Jacob O. Michalowski, P.E.
Engineer II Senior Engineer
Copyright 2020American Engineering Testing, Inc.
All Rights Reserved
Unauthorized use or copying of this document is strictly prohibited by anyone other than the client for the specific project.
Page ii
Report of Geotechnical Exploration
Jamaica Avenue Improvements - Cottage Grove, MNAMERICAN
July 2, 2020ENGINEERING
AET Report No. 28-20309TESTING, INC.
TABLE OF CONTENTS
Transmittal Letter............................................................................................................................. i
Signature Page ................................................................................................................................ ii
TABLE OF CONTENTS ............................................................................................................... iii
1.0INTRODUCTION.................................................................................................................... 1
2.0 SCOPE OF SERVICES............................................................................................................ 1
3.0 PROJECT INFORMATION..................................................................................................... 1
4.0 SUBSURFACE EXPLORATION AND TESTING................................................................ 1
4.1 Ground Penetrating Radar ..................................................................................................... 2
4.2 Falling Weight Deflectometer............................................................................................... 2
4.3 Field Exploration Program.................................................................................................... 3
4.4 Laboratory Testing ................................................................................................................ 3
5.0 SITE CONDITIONS................................................................................................................. 4
5.1 GPR Data ............................................................................................................................... 4
5.2 Pavement Section .................................................................................................................. 4
5.3 Subgrade Soils ....................................................................................................................... 6
5.4 FWD Results.......................................................................................................................... 6
5.5 Groundwater .......................................................................................................................... 6
6.0 ASTM STANDARDS.............................................................................................................. 7
7.0 CONCLUDING COMMENTS................................................................................................ 7
APPENDIX A – Geotechnical Field Exploration and Testing
Boring Log Notes
Unified Soil Classification System
AASHTO Soil Classification System
Figure 1 –Testing Location Map
Pavement Core Logs
Subsurface Boring Logs
Gradation Curves
APPENDIX B –Falling Weight Deflectometer Testing
Figure 2 – Effective Subgrade R-Value Map
APPENDIX C – Ground Penetrating Radar Testing
Jamaica Avenue Northbound Plot
Jamaica Avenue Southbound Plot
APPENDIX D – Geotechnical Report Limitations and Guidelines for Use
Page iii
Report of Geotechnical Exploration
Jamaica Avenue Improvements -Cottage Grove, MNAMERICAN
July 2, 2020ENGINEERING
AET Report No. 28-20309TESTING, INC.
1.0INTRODUCTION
The City of Cottage Grove (the City) and Bolton & Menk, Inc. (BMI)are proposing improvements
to a segment of Jamaica Avenuein Cottage Grove, Minnesota. To assist planning and design, you
have authorized American Engineering Testing, Inc. (AET) to conduct a subsurface exploration
program at the siteandconduct soil laboratory testing,This report presents the results of the above
services, an
2.0 SCOPE OF SERVICES
AET's services wereperformed according toour proposal to you datedMay 6, 2020. The
authorized scope consists of:
Obtaining eleven4-inchpavement cores.
Drilling and sampling elevenstandard penetration test (SPT) boringsto depths of 6feetat
the pavement core locations.
Conducting a Ground Penetrating Radar (GPR)survey in both directions of travel and both
lanes.
th
Performing Falling Weight Deflectometer (FWD) testing at 1/10mile incrementsineach
direction andboth right lanes.
Conducting soillaboratory testing.
Preparation of this report.
These services areintendedfor geotechnical purposes. Thescope is not intended to explore for the
presence or extent of environmental contamination.
3.0PROJECT INFORMATION
We understand the City and BMI are proposing improvements to a 2.1-mile section of Jamaica
Avenuefrom Highway 61 to Indian Blvd in Cottage Grove, Minnesota. The bituminous-surfaced
road is a 4-lane divided road.The annual average daily traffic (AADT)along the road reportedly
varies from 6,400vehicles per dayin the northern sections to 21,900 vehicles per day near
Highway 61.The traffic data was obtained from the MnDOT Traffic Mapping Application.
4.0SUBSURFACE EXPLORATIONAND TESTING
The subsurface exploration program conducted for the project consisted ofground penetrating
radar (GPR) testing, falling weight deflectometer (FWD) testing, elevenstandard penetration test
(SPT) borings, and elevenpavement cores.
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Jamaica Avenue Improvements - Cottage Grove, MNAMERICAN
July 2, 2020ENGINEERING
AET Report No. 28-20309TESTING, INC.
4.1Ground Penetrating Radar
The pavement thickness testing program conducted for the project consisted of a high speed (air
coupled) GPR antenna collecting pavement thickness data. The
datawas collected using a 2 GHz antenna,whichallowsmateriallayermeasurementsatdepths
ofupto approximately 18 inches with a resolution less than about ½-inch.Thedatacollected
islinkedto GPS and allows us to plot the data on a graph. TheGPRtest data and
details of the methods used appear in Appendix C.
The GPR data was collected on May 18, 2020. Scansof the pavement were collected according to
SIR-30 processor settings established by GSSI RoadScan system, in both the northbound and
southbounddirections of the right and left lanes.Acalibration file, required for data post-
processing, was collected at the beginning of the testing day.
GPR interface identification was accomplished using RADAN 7.0,a proprietary software package
included with the GSSI RoadScan system. The software includes tools to aid in delineating
pavement layer transitions, and it automatically calculates their depths from the pavement surface
using the calibration file(s) collected prior to testing. The identified layers were compared to the
soil boring and pavement core data collected at specificlocations to validate the accuracy of the
layer thicknesses.
Depending on pavement age and condition, the presence of moisture, ambient electromagnetic
interference, and pavement structure, total depths of asphalt and aggregate base are not always
explicitly clear. Where gaps in clear identification of pavement and base layer thicknesses are
encountered,the results arereported as a percent of the picking rate of the layer interface. A
picking rate of 100 percent indicates the layer interfaces were visible in 100 percent of the scanned
points.
4.2 Falling Weight Deflectometer
Thepavement deflection testing program conducted for the project consisted of falling weight
deflectometer (FWD) testing at approximately 0.1-mile interval spacing in the right lanes of both
northbound and southbound directions.The FWDtesting was performed on May 19, 2020 using
a Dynatest 8000FWD.
After seating drops, data for four impulse loads (two at 6,000 lbs. and two at 9,000 lbs. nominal
load) were collected at each test point. The FWD test resultsand details of the methods used appear
in Appendix B.
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Jamaica Avenue Improvements -Cottage Grove, MNAMERICAN
July 2, 2020ENGINEERING
AET Report No. 28-20309TESTING, INC.
The deflection data was analyzed using MnDOT methods for determining the in-place (effective)
subgrade and pavement strength, as well as allowable axle loads for a roadway (MnDOT
Investigation 183 revised in 1983). The MnDOT methods use the Hogg Model for estimating the
subgrade modulus. The effective GE of a pavement system is estimated from the deflection
relationship equation, derived from MnDOT Investigations 183 and 195. Our methodology uses
MnDOT’s Investigation 183 for calculation of an estimated load capacity in late spring and
required overlay to estimate the structure for future assumed traffic loading.
4.3Field Exploration Program
After preliminary review of the GPR data, AETselected elevensoil boring and pavement core
locations. Before drilling, we contacted Gopher State One Call tolocatepublic underground
utilities.The pavement cores and soil borings wereperformed on June 3, 2020.
Pavement core logs are provided in Appendix A. These logs include a photograph of the extracted
core, as well as total recovered core height, liftthicknesses (where visible), and comments on
pavement condition.
Subsurface boringlogs and details of the methods used appear in Appendix A. The boring logs
contain information concerning soil layering, soil classification, geologic description, and
moisture condition. Relative density or consistency is also noted for the natural soils, which is
based on the standard penetration resistance (N-value).
Borings B-2 through B-6 were performed in the northbound right lane, and borings B-7 through
B-10 were performed in the southbound right lane. Boring B-1 was performed in the northbound
right turn laneto E Point Douglas Road, and boring B-11 was performed in the southbound right
turn laneto E Point Douglas Road.The locations of the pavement cores and soil boringsare
illustrated on the Figure 1 –Testing Locations Mappreceding the pavement corelogsand
subsurface boring logsin Appendix A.The soil boring locations were recordedin the field by AET
personnel using a GPS unit. The elevations at the boring locations were not recorded.
4.4Laboratory Testing
The laboratory test program included foursieve analyses.The water contentand the percent
passing the #200 sieve results appearon the individual boring logs adjacent to the samples upon
which they were performed.The full sieve analysis test results are shown on the Gradation Curves
sheet in AppendixAfollowing the boring logs.
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Jamaica Avenue Improvements -Cottage Grove, MNAMERICAN
July 2, 2020ENGINEERING
AET Report No. 28-20309TESTING, INC.
5.0SITE CONDITIONS
5.1GPR Data
The GPR data shows clear interfacesbetween the bituminous pavement andpossible aggregate
baselayer and between the possible aggregate base layer and underlying material both with a
picking rate of 100%. Thepavement cores andsoil borings were used to aid in the interpretation
of the GPR layer interfaces.
The GPR plots are included in Appendix C toillustrate the thickness of the identified bituminous
and base layers within both the right and left lanes of northbound and southbound.The values
presented in Tables1and 2 below were determined using 25-foot interval averages. The 15th
percentile represents the value at which 85% of the section has a pavement layer thickness that is
greater than identified. This is the value we generally recommend using for pavement design
purposes.
Table 1-GPR Thickness Summary NB Lanes
NB Left LaneNB Right Lane
Layer
AverageCV15thMin.AverageCV15thMin.
BP5.611%5.04.55.515%4.74.2
Base5.724%4.32.47.324%5.43.5
BP + Base11.312%10.07.112.816%10.58.4
thth
Note: BP –Bituminous Pavement. CV –coefficient of variation(Std Dev/Average). 15–15percentile thickness value.
Table 2-GPR Thickness Summary SB Lanes
SB Left LaneSB Right Lane
Layer AverageCV15thMin.AverageCV15thMin.
BP5.514%4.84.25.615%4.84.3
Base5.223%4.02.46.123%4.71.8
BP + Base10.712%9.47.411.712%10.37.7
thth
Note: BP –Bituminous Pavement. CV –coefficient of variation(Std Dev/Average). 15–15percentile thickness value.
5.2Pavement Section
The pavement encountered at the core and soil boring locations consists of bituminousover a
possible aggregate base layer.Table 3below presentsthe bituminous and aggregate basethickness
found atthe pavementcore/boringlocations.
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Jamaica Avenue Improvements -Cottage Grove, MNAMERICAN
July 2, 2020ENGINEERING
AET Report No. 28-20309TESTING, INC.
Table 3-PavementThickness Summary
Extracted CoreDownhole Approximate
Pavement Bituminous Bituminous BaseApproximate Total
AB.C.B.
CoreThickness (in)Thickness (in) Thickness (in)Thickness (in)
B-17.67¾310¾
B-24.95813
B-36.16915
B-45.35½510½
B-55.761117
B-65.25½510½
B-74.45510
B-85.67½512½
B-95.05½611½
B-105.65½8½14
B-112.97¼411¼
Notes:A. Average of three measurements of the core measured to the nearest 0.1-inch.
B. From borings and rounded to the nearest ¼-inch.
C. From borings and rounded to the nearest ½-inch.
The core lift thicknesses reported on the core logs are from the top down at one location along the
core. The noted lift thicknesses were interpreted by AET. In summary, the bituminous thickness
encountered at the soil boring and pavement core locations varies from5 to 7¾ inches. The
possible aggregate base material varies fromabout3inches to11inchesand consists mostly of
gravelly silty sand (A-1-b) and sand (A-1-b).
Bituminous condition was also evaluated based on the pavement cores obtained at the site.
Photographs of the pavement cores are providedon the pavement core logsin Appendix A.The
pavement cores indicateslightto severe stripping.The core from boring B-11 crumbled during
coring operationsand was not fully recovered.Additionally, a possible chip seal was observed at
the surface of all eleven cores.
Stripping occurs when water or water vapor gets between the asphalt film and the aggregates,
thereby breaking the adhesive bond between the aggregate and asphalt binder. This will “strip” the
asphalt from the aggregate, eventually leading to pavement failure. When stripping within the
pavement becomes excessive, severe pavement deformation and fatigue cracking will occur, and
then traffic loadings will result in local failures such as alligator cracking, potholes, and excessive
rutting in the wheel paths.
Page5of 7
Report of Geotechnical Exploration
Jamaica Avenue Improvements -Cottage Grove, MNAMERICAN
July 2, 2020ENGINEERING
AET Report No. 28-20309TESTING, INC.
5.3SubgradeSoils
The subgradesoils encountered in the borings below thepossible aggregatebase courseconsist
mostly of additional fill soils consisting of sand with silt (A-2-4), silty sand (A-2-4), and sand (A-
3). The fill soils extended to depths of between 1 foot and to the final drilling depths of 6 feet.
Below the fill, medium dense to very dense sand (A-3) alluvial soils were encountered and
extended to the final drilling depths of 6 feet.
5.4FWD Results
Figure 1 in Appendix Aillustrates the locations of the FWD tests. Figure 2 in Appendix B shows
the effective subgrade R-value from each of the FWD tests. All FWD tests were performed in the
right lanes.Table 4below provides a summary of theFWDtesting that was analyzed using
MnDOT TONN 2010 software. The results showthatthe upper 3 to 4 feet of the existing subgrade
has good soil support.
Table 4. FWD Test Results.
Effective REffective GE
RoadwayFromToLane
AvgCV15thAvgCV15th
East Point
Jamaica AveRoundaboutNB32.9NANA31.9NANA
Douglas Rd
East Point Douglas
Jamaica Ave90th StNB55.4NANA33.0NANA
Rd
Jamaica Ave90th StHillside TrlNB26.316%21.726.27%23.5
Jamaica AveHillside Trl80th StNB40.315%35.033.07%30.4
Jamaica Ave80th St75th StNB36.928%23.731.111%25.7
Jamaica Ave75th StIndian BlvdNB33.611%30.530.98%27.4
Jamaica AveIndian Blvd75th StSB44.716%36.929.58%26.2
Jamaica Ave75th St80th StSB30.013%24.824.69%22.0
Jamaica Ave80th StHillside TrlSB36.99%34.030.56%27.9
Jamaica AveHillside Trl90th StSB31.89%28.630.66%28.9
East Point
Jamaica Ave90th StSB41.616%35.530.610%27.4
Douglas Rd
East Point Douglas
Jamaica AveRoundaboutSB37.9NANA37.0NANA
Rd
thth
Note: CV –coefficient of variation(Std Dev/Average). 15–15percentile thickness value.
5.5Groundwater
Groundwater was not observed inour soil borings during the geotechnical exploration.Due to the
relatively high permeability of most of the soilsencountered,it is our opinion that themeasured
water levelsshould provide an accurateindication or lack thereof the groundwater levelat the time
Page6of 7
Report of Geotechnical Exploration
Jamaica Avenue Improvements -Cottage Grove, MNAMERICAN
July 2, 2020ENGINEERING
AET Report No. 28-20309TESTING, INC.
of drilling.Groundwater levels donot remainconstant; they fluctuate due to varying seasonal and
annual rainfall and snow melt amounts, as well as other factors.
6.0 ASTMSTANDARDS
When we refer to an ASTM Standard in this report, we mean that our services were performed in
general accordance with that standard. Compliance with any other standards referenced within the
specified standard is neither inferred nor implied.
7.0 CONCLUDING COMMENTS
Within thelimitations of scope, budget, and schedule, we have endeavored to provide our services
according to generally accepted geotechnical engineering practices at this time and location. Other
than this, no warranty, either express or implied, is intended.
Page7of 7
Appendix A
Geotechnical Field Exploration andTesting
Boring Log Notes
Unified Soil Classification System
AASHTO Soil Classification System
Pavement CoreReports
Subsurface Boring Logs
Gradation Curves
Appendix A
Geotechnical Field Exploration and Testing
AET Project 28-20309
A.1 FIELD EXPLORATION
The subsurface conditions at the site were explored by drilling and samplingelevenStandard Penetration Test (SPT) boringsand
elevenpavement cores. The locations of the borings appear on the Boring Location Maps, preceding the Subsurface Boring Logs
in this appendix.
A.2 SAMPLING METHODS
A.2.1 Split-Spoon Samples (SS) - Calibrated to NValues
60
Standard penetration (split-spoon) samples were collected in general accordance with ASTM: D1586 with one primary
modification. The ASTM test method consists of driving a 2-inch O.D. split-barrel sampler into the in-situ soil with a 140-pound
hammer dropped from a height of 30 inches. The sampler is driven a total of 18 inches into the soil. After an initial set of 6 inches,
the number of hammer blows to drive the sampler the final 12 inches is known as the standard penetration resistance or N-value.
Our method uses a modified hammer weight, which is determined by measuring the system energy using a Pile Driving Analyzer
(PDA) and an instrumented rod.
In the past, standard penetration N-value tests were performed using a rope and cathead for the lift and drop system. The energy
transferred to the split-spoon sampler was typically limited to about 60% of its potential energy due to the friction inherent in this
blow count.
system. This converted energy then provides what is known as an N
60
The most recent drill rigs incorporate an automatic hammer lift and drop system, which has higher energy efficiency and
subsequently results in lower N-values than the traditional Nvalues. By using the PDA energy measurement equipment, we can
60
determine actual energy generated by the drop hammer. With the various hammer systems available, we have found highly
variable energies ranging from 55% to over 100%. Therefore, the intent of AET’s hammer calibrations is to vary the hammer
weight such that hammer energies lie within about 60% to 65% of the theoretical energy of a 140-pound weight falling 30 inches.
The current ASTM procedure acknowledges the wide variation in N-values, stating that N-values of 100% or more have been
observed.Although we have not yet determined the statistical measurement uncertainty of our calibrated method to date, we can
state that the accuracy deviation of the N-values using this method is significantly better than the standard ASTM Method.
A.2.2 Disturbed Samples (DS)/Spin-up Samples (SU)
Sample types described as “DS” or “SU” on the boring logs are disturbed samples, which are taken from the flights of the auger.
Because the auger disturbs the samples, possible soil layering and contact depths should be considered approximate.
A.2.3 Sampling Limitations
Unless observedin a sample, contacts between soil layers are estimated based on the spacing of samples and the action of drilling
tools. Cobbles, boulders, and other large objects generally cannot be recovered from test borings, and they may be present inthe
ground even if they are not noted on the boring logs.
Determining the thickness of “topsoil” layers is usually limited, due to variations in topsoil definition, sample recovery, and other
factors. Visual-manual description often relies on color for determination, and transitioning changes can account for significant
variation in thickness judgment. Accordingly, the topsoil thickness presented on the logs should not be the sole basis for
calculating topsoil stripping depths and volumes. If more accurate information is needed relating to thickness and topsoil quality
definition, alternate methods of sample retrieval and testing should be employed.
A.3 CLASSIFICATION METHODS
Soil descriptions shown on the boring logs are based on the Unified Soil Classification (USC) system. The USC system is described
in ASTM: D2487 and D2488. Where laboratory classification tests (sieve analysis or Atterberg Limits) have been performed,
accurate classifications per ASTM: D2487 are possible. Otherwise, soil descriptions shown on the boring logs are visual-manual
judgments. Charts are attached which provide information on the USC system, the descriptive terminology, and the symbols used
on the boring logs.A chart explaining the USC system is attached in Appendix A.
Visual-manual judgment of the AASHTO Soil Group is also noted as a part of the soil description. A chart presenting details of the
AASHTO Soil Classification System is also attached.
Appendix A - Page 1 of 2AMERICAN ENGINEERING TESTING, INC.
Appendix A
Geotechnical Field Exploration and Testing
AET Project 28-20309
A.4 WATER LEVEL MEASUREMENTS
The ground water level measurements are shown at the bottom of the boring logs. The following information appears under “Water
Level Measurements” on the logs:
Date and Time of measurement
lowest depth of soil sampling at the time of measurement
Sampled Depth:
depth to bottom of casing or hollow-stem auger at time of measurement
Casing Depth:
depth at which measuring tape stops in the borehole
Cave-in Depth:
Water Level: depth in the borehole where free water is encountered
Drilling Fluid Level: same as Water Level, except that the liquid in the borehole is drilling fluid
The true location of the water table at the boring locations may be different than the water levels measured in the boreholes. This is
possible because there are several factors that can affect the water level measurements in the borehole. Some of these factors include:
permeability of each soil layer in profile, presence of perched water, amount of time between water level readings, presence of
drilling fluid, weather conditions, and use of borehole casing.
A.5 LABORATORY TEST METHODS
A.5.1 Sieve Analysis of Soils (thru #200 Sieve)
Conducted per AET Procedure 01-LAB-040, which is performed in general conformance withASTM: D6913, Method A.
A.6 TEST STANDARD LIMITATIONS
Field and laboratory testing is done in general conformance with the described procedures. Compliance with any other standards
referenced within the specified standard is neither inferred nor implied.
A.7 SAMPLE STORAGE
Unless notified to do otherwise, we routinely retain representative samples of the soils recovered from the borings for a period of 30
days.
Appendix A - Page 2 of 2AMERICAN ENGINEERING TESTING, INC.
BORINGLOGNOTES
DRILLING AND SAMPLING SYMBOLS TEST SYMBOLS
Symbol Definition Symbol Definition
AR: Sample of material obtained from cuttings blown out CONS: One-dimensional consolidation test
the top of the borehole during air rotary procedure. DEN: Dry density, pcf
B, H, N: Size of flush-joint casing DST: Direct shear test
CAS: Pipe casing, number indicates nominal diameter in E: Pressuremeter Modulus, tsf
inches HYD: Hydrometer analysis
COT: Clean-out tube LL: Liquid Limit, %
DC: Drive casing; number indicates diameter in inches LP: Pressuremeter Limit Pressure, tsf
DM: Drilling mud or bentonite slurry OC: Organic Content, %
DR: Driller (initials) PERM: Coefficient of permeability (K) test; F - Field;
DS: Disturbed sample from auger flights L- Laboratory
DP: Direct push drilling; a 2.125 inch OD outer casing PL: Plastic Limit, %
with an inner 1½ inch ID plastic tube is driven q: Pocket Penetrometer strength, tsf (approximate)
p
continuously into the ground. q: Static cone bearing pressure, tsf
c
FA: Flight auger; number indicates outside diameter in q: Unconfined compressive strength, psf
u
inches R: Electrical Resistivity, ohm-cms
HA: Hand auger; number indicates outside diameter RQD: Rock Quality Designation of Rock Core, in percent
HSA: Hollow stem auger; number indicates inside diameter (aggregate length of core pieces 4" or more in length
in inches as a percent of total core run)
LG: Field logger (initials) SA: Sieve analysis
MC: Column used to describe moisture condition of TRX: Triaxial compression test
samples and for the ground water level symbols VSR: Vane shear strength, remolded (field), psf
N (BPF): Standard penetration resistance (N-value) in blows per VSU: Vane shear strength, undisturbed (field), psf
foot (see notes) WC: Water content, as percent of dry weight
NQ: NQ wireline core barrel %-200: Percent of material finer than #200 sieve
PQ: PQ wireline core barrel
RDA: Rotary drilling with compressed air and roller or drag
STANDARD PENETRATION TEST NOTES
bit.
(Calibrated Hammer Weight)
RDF: Rotary drilling with drilling fluid and roller or drag bit
The standard penetration test consists of driving a split-spoon
REC: In split-spoon (see notes), direct push and thin-walled
sampler with a drop hammer (calibrated weight varies to provide
tube sampling, the recovered length (in inches) of
N values) and counting the number of blows applied in each of
60
sample. In rock coring, the length of core recovered
three 6" increments of penetration. If the sampler is driven less
(expressed as percent of the total core run). Zero
than 18" (usually in highly resistant material), permitted in
indicates no sample recovered.
ASTM: D1586, the blows for each complete 6" increment and for
SS: Standard split-spoon sampler (steel; 1.5" is inside
each partial increment is on the boring log. For partial increments,
diameter; 2" outside diameter); unless indicated
the number of blows is shown to the nearest 0.1' below the slash.
otherwise
SU Spin-up sample from hollow stem auger
The length of sample recovered, as shown on the REC column,
TW: Thin-walled tube; number indicates inside diameter in
may be greater than the distance indicated in the N column. The
inches
disparity is because the N-value is recorded below the initial 6"
WASH: Sample of material obtained by screening returning
set (unless partial penetration defined in ASTM: D1586 is
rotary drilling fluid or by which has collected inside
encountered) whereas the length of sample recovered is for the
fallingthrough drilling fluid
entire sampler drive (which may even extend more than 18").
WH: Sampler advanced by static weight of drill rod and
hammer
WR: Sampler advanced by static weight of drill rod
94mm: 94 millimeter wireline core barrel
: Water level directly measured in boring
: Estimated water level based solely on sample
appearance
01REP052C (7/11) AMERICAN ENGINEERING TESTING, INC.
AMERICAN
UNIFIED SOIL CLASSIFICATION SYSTEM
ENGINEERING
ASTM Designations: D 2487, D2488
TESTING, INC.
Soil Classification
Notes
A
BA
Criteria for Assigning Group Symbols and Group Names Using Laboratory Tests
Group Group Name
Based on the material passing the 3-in
Symbol
(75-mm) sieve.
B
EF
If field sample contained cobbles or
Coarse-Grained Gravels MoreClean GravelsCu>4 and 1<Cc<3GWWell graded gravel
Soils More than 50% coarse Less than 5%
EF
C
Cu<4 and/or 1>Cc>3GPPoorly graded gravel
than 50%fraction retained fines
C
Gravels with 5 to 12% fines require dual
retained onon No. 4 sieve
F.G.H
Gravels with Fines classify as ML or MHGMSilty gravel
symbols:
No. 200 sieve
Fines more
GW-GM well-graded gravel with silt
CF.G.H
than 12% fines Fines classify as CL or CHGCClayey gravel
GW-GC well-graded gravel with clay
GP-GM poorly graded gravel with silt
EI
GP-GC poorly graded gravel with clay
Sands 50% orClean SandsCu>6 and 1<Cc<3SWWell-graded sand
D
more of coarseLess than 5%Sands with 5 to 12% fines require dual
DEI
fraction passesfinesCu<6 and/or1>Cc>3SPPoorly-graded sandsymbols:
No. 4 sieve SW-SM well-graded sand with silt
G.H.I
Sands with Fines classify as ML or MHSMSilty sand SW-SC well-graded sand with clay
Fines more SP-SM poorly graded sand with silt
DG.H.I
than 12% fines Fines classifyas CL or CHSCClayey sand SP-SC poorly graded sand with clay
K.L.M
Fine-Grained Silts and ClaysinorganicPI>7 and plots on or aboveCLLean clay
2
J
(D)
Soils 50% orLiquid limit less
30
E
K.L.M
Cu = D/D Cc =
more passesthan 50
6010,
PI<4 or plots below MLSilt
J
Dx D
the No. 200
10 60
K.L.M.N
sieve
organicOLOrganic clay
Liquid limitoven dried
F
<0.75
If soil contains >
K.L.M.O
Liquid limit not dried
Organic silt
(see Plasticity
G
If fines classify as CL-ML, use dual
Chart below)
K.L.M
symbol GC-GM, or SC-SM.
Silts and ClaysinorganicCHFat clay
H
Liquid limit 50
K.L.M
or morePI plots MHElastic silt
I
If soil contains >
K.L.M.P
group name.
organicOHOrganic clay
Liquid limitoven dried
<0.75
J
If Atterberg limits plot is hatched area,
Liquid limit not dried K.L.M.Q
Organic silt
soilis a CL-ML silty clay.
K
R
If soil contains 15 to 29% plus No. 200
PTPeat
Highly organic Primarily organic matter, dark
soilin color, and organic in odor
whichever is predominant.
L
If soil contains >30% plus No. 200,
60
SIEVE ANALYSIS
For classification of fine-grained soils and
Screen Opening (in.)Sieve Number
group name.
fine-grained fraction of coarse-grained soils.
321½1¾410204060140200
8
M
50
If soil contains >30% plus No. 200,
100 0
Equation of "A"-line
Horizontal at PI = 4 to LL = 25.5.
then PI = 0.73 (LL-20)
to group name.
80 20
40
N
Equation of "U"-line
Pl>
Vertical at LL = 16 to PI = 7.
O
D 60 = 15mm
then PI = 0.9 (LL-8)
60 40
30
P
Q
.
40 60
R
20
Fiber Content description shown below.
D 30 = 2.5mm
MH OR OH
20 80
10
D 10 = 0.075mm
7
CL-ML
ML OR OL
4
0100
0
0.1
501051.00.5
010162030405060708090100110
PARTICLE SIZE IN MILLIMETERS
LIQUID LIMIT (LL)
22
D 60 15(D 30)2.5
C u = = = 200C c = = = 5.6
Plasticity Chart
D 10 0.075D 10 x D 60 0.075 x 15
ADDITIONAL TERMINOLOGY NOTES USED BY AET FOR SOIL IDENTIFICATION AND DESCRIPTION
Gravel Percentages
Grain SizeConsistency of Plastic SoilsRelative Density of Non-Plastic Soils
Term Percent
Term Particle Size Term N-Value, BPF Term N-Value, BPF
A Little Gravel 3% -14%
Boulders Over 12"Very Soft less than 2Very Loose 0 -4
With Gravel 15% -29%
Cobbles 3" to 12"Soft 2 -4Loose 5 -10
Gravelly 30% -50%
Gravel #4 sieve to 3"Firm 5 -8Medium Dense 11 -30
Sand #200 to #4 sieveStiff 9 -15Dense 31 -50
Fines (silt & clay) Pass #200 sieveVery Stiff 16 -30Very Dense Greater than 50
Hard Greater than 30
Moisture/Frost ConditionLayering NotesPeatDescriptionOrganicDescription (if no lab tests)
(MC Column)Soils are described as organic, if soil is not peat
D (Dry): Absence of moisture, dusty, dry to and is judged to have sufficient organic fines
Laminations: Layers less than Fiber Content
touch.content to influence the Liquid Limitproperties.
½" thick of Term (Visual Estimate)
M (Moist): Damp, although free water not Slightly organicused for borderline cases.
differing material
visible. Soil may still have a high Root Inclusions
or color.Fibric Peat: Greater than 67%
.With roots: Judged to have sufficient quantity
Hemic Peat: 33 67%
W (Wet/ Free water visible,intended to of roots to influence the soil
Lenses: Pockets or layers Sapric Peat: Less than 33%
Waterbearing): describe non-plastic soils. properties.
greater than ½"
Waterbearing usually relates toTrace roots: Small roots present, but not judged
thick of differing
sands and sand with silt. to be in sufficient quantity to
material or color.
F (Frozen): Soil frozen significantly affect soil properties.
01CLS021 (07/08)AMERICAN ENGINEERING TESTING, INC.
AASHTO SOIL CLASSIFICATION SYSTEM
AMERICAN ASSOCIATION OF STATE HIGHWAY AND TRANSPORTATION OFFICIALS
Classification of Soils and Soil-Aggregate Mixtures
Granular MaterialsSilt-Clay Materials
General Classification
(35% or less passing No. 200 sieve)(More than 35% passing No. 200 sieve)
A-1A-2
A-7
Group Classification
A-7-5
A-1-aA-1-bA-3A-2-4A-2-5A-2-6A-2-7A-4A-5A-6
A-7-6
Sieve Analysis, Percent passing:
No. 10 (2.00 mm) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...................50 max.. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .
No. 40 (0.425 mm) . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...................30 max.50 max.51 min.. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .
No. 200 (0.075 mm) . . . . . . . . . . . . . . . . . . . . . . . . . . . . ....................15 max.25 max.10 max.35 max.35 max.35 max.35 max.36 min.36 min.36 min.36 min.
Characteristics of Fraction Passing No. 40 (0.425 mm)
. . . .
Liquid limit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .................. . . .40 max.41 min.40 max.41 min.40 max.41 min.40 max.41 min.
6 max.
Plasticity index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .................N.P.10 max.10 max.11 min.11 min.10 max.10 max.11 min.11 min.
Stone Fragments, Fine
Usual Types of Significant Constituent MaterialsSilty or Clayey Gravel and SandSilty SoilsClayey Soils
Gravel and SandSand
Excellent to GoodFair to Poor
General Ratings as Subgrade . . . . . . . . . . . . . . . . . . . . . .....................
The placing of A-3 before A-2 is necessary in the "left to right elimination process" and does not indicate superiority of A-3 over A-2.
Plasticity index of A-7-5 subgroup is equal to or less than LL minus 30. Plasticity index of A-7-6 subgroup is greater than LL minus 30.
Group A-8 soils are organic clays or peat with organic content >5%.
PLASTICITY INDEX (PI)
GROUP INDEX CHART
5015
Group Index (GI) = (F-35) \[0.2+0.005 (LL-40) \] + 0.01 (F-15)
010203040506070
100
(PI-10) where F = % Passing No. 200 sieve, LL = Liquid
Limit, and PI = Plasticity Index.
20
When working with A-2-6 and A-2-7 subgroups
90
the Partial Group Index (PGI) is determined from the
PI only.
30
80
40
When the combined Partial Group Indices are
negative, the Group Index should be reported as zero.
35
70
40
60
30
50
50A-5A-7
60
40
20
30A-4A-6
70
20
80
10
10
Liquid Limit and Plasticity Index Ranges for the
A-4, A-5, A-6 and A-7 Subgroups
90
Definitions of Gravel, Sand and Silt-Clay
The terms "gravel", "coarse sand", "fine sand" and "silt-clay", as
determinable from the minimum test data required in this
classification arrangement and as used in subsequent word
0
100
descriptions are defined as follows:
GRAVEL - Material passing sieve with 3-in. square openings and retained on
Example:Then:
the No. 10 sieve.
82% Passing No. 200 sievePGI = 8.9 for LL
COARSE SAND - Material passing the No. 10 sieve and retained on the No.
LL = 38PGI = 7.4 for PI
40 sieve.
GI = 16
PI = 21
FINE SAND - Material passing the No. 40 sieve and retained on the No. 200
sieve.
-10
COMBINED SILT AND CLAY - Material passing the No. 200 sieve
BOULDERS (retained on 3-in. sieve) should be excluded from the portion of
the sample to which the classificaiton is applied, but the percentage of such
material, if any, in the sample should be recorded.
The term "silty" is applied to fine material having plasticity index of 10 or less
and the term "clayey" is applied to fine material having plasticity index of 11 or
greater.
01CLS022 (07/11)AMERICAN ENGINEERING TESTING, INC.
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Testing Locations
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Geotechnical Data Report
!
E NGINEERING
Jamaica Avenue Improvements
92nd St S
St S
92nd
±
T ESTING, I NC
Cottage Grove, Minnesota
0400800
Date: 06/26/2020AET Project No. 28-20309
Feet
File: 28-20309P-1.mxd Date: 06/26/2020
CONSULTANTS
·ENVIRONMENTAL
·GEOTECHNICAL
·MATERIALS
·FORENSICS
PAVEMENT CORE LOG
Jamaica Avenue Improvements – Cottage Grove, Minnesota
AET Project Number:28-20309
Core: B-1
Date Cored: June 2, 2020
Description:
Core Diameter:4”
TotalCore Height:7.”
Lift 1: 2.2”
Lift 2: 1.6”
Lift 3: 1.5”
Lift 4: 2.5”
Comments:
Possible chip seal at the surface.
Core contains slight stripping
throughout. Lift 4 contains slight
to moderate stripping.
550 Cleveland Avenue North | Saint Paul, MN 55114
Phone (651) 659-9001 | (800) 972-6364 | Fax (651) 659-1379 | www.amengtest.com | AA/EEO
This document shall not be reproduced, except in full, without written approval from American Engineering Testing, Inc.
CONSULTANTS
·ENVIRONMENTAL
·GEOTECHNICAL
·MATERIALS
·FORENSICS
PAVEMENT CORE LOG
Jamaica Avenue Improvements – Cottage Grove, Minnesota
AET Project Number:28-20309
Core: B-2
Date Cored: June 2, 2020
Description:
Core Diameter: 4”
Total Core Height: 4.9”
Lift 1: 1.9”
Lift 2: 3.0”
Comments:
Possible chip seal at the surface.
Core contains moderate stripping
throughout.
550 Cleveland Avenue North | Saint Paul, MN 55114
Phone (651) 659-9001 | (800) 972-6364 | Fax (651) 659-1379 | www.amengtest.com | AA/EEO
This document shall not be reproduced, except in full, without written approval from American Engineering Testing, Inc.
CONSULTANTS
·ENVIRONMENTAL
·GEOTECHNICAL
·MATERIALS
·FORENSICS
PAVEMENT CORE LOG
Jamaica Avenue Improvements – Cottage Grove, Minnesota
AET Project Number:28-20309
Core: B-3
Date Cored: June 2, 2020
Description:
Core Diameter: 4”
Total Core Height: 6.1”
Lift 1: 1.3”
Lift 2: 1.2”
Lift 3: 1.5”
Lift 4: 2.1”
Comments:
Possible chip seal at the surface.
Core has slight to moderate
stripping throughout.
550 Cleveland Avenue North | Saint Paul, MN 55114
Phone (651) 659-9001 | (800) 972-6364 | Fax (651) 659-1379 | www.amengtest.com | AA/EEO
This document shall not be reproduced, except in full, without written approval from American Engineering Testing, Inc.
CONSULTANTS
·ENVIRONMENTAL
·GEOTECHNICAL
·MATERIALS
·FORENSICS
PAVEMENT CORE LOG
Jamaica Avenue Improvements – Cottage Grove, Minnesota
AET Project Number:28-20309
Core: B-4
Date Cored: June 2, 2020
Description:
Core Diameter: 4”
Total Core Height: 5.3”
Lift 1: 2.0”
Lift 2: 1.5”
Lift 3: 1.8”
Comments:
Possible chip seal at the surface.
Lift 1 contains slight stripping.
Lifts 2 and 3 contain moderate
to severe stripping.
550 Cleveland Avenue North | Saint Paul, MN 55114
Phone (651) 659-9001 | (800) 972-6364 | Fax (651) 659-1379 | www.amengtest.com | AA/EEO
This document shall not be reproduced, except in full, without written approval from American Engineering Testing, Inc.
CONSULTANTS
·ENVIRONMENTAL
·GEOTECHNICAL
·MATERIALS
·FORENSICS
PAVEMENT CORE LOG
Jamaica Avenue Improvements – Cottage Grove, Minnesota
AET Project Number:28-20309
Core: B-5
Date Cored: June 2, 2020
Description:
Core Diameter: 4”
Total Core Height: 5.7”
Lift 1: 2.2”
Lift 2: 1.9”
Lift 3: 1.6”
Comments:
Possible chip seal at the surface.
Lifts 1 and 2 contains slight stripping.
Lift 3 contains moderate stripping.
550 Cleveland Avenue North | Saint Paul, MN 55114
Phone (651) 659-9001 | (800) 972-6364 | Fax (651) 659-1379 | www.amengtest.com | AA/EEO
This document shall not be reproduced, except in full, without written approval from American Engineering Testing, Inc.
CONSULTANTS
·ENVIRONMENTAL
·GEOTECHNICAL
·MATERIALS
·FORENSICS
PAVEMENT CORE LOG
Jamaica Avenue Improvements – Cottage Grove, Minnesota
AET Project Number:28-20309
Core: B-6
Date Cored: June 2, 2020
Description:
Core Diameter: 4”
Total Core Height: 5.2”
Lift 1: 1.7”
Lift 2: 1.2”
Lift 3: 2.3”
Comments:
Possible chip seal at the surface.
Lift 1 contains moderate to severe
stripping. Bottom of lift 1 contained
large voids. Lifts 2 and 3 contains
slight to moderate stripping.
550 Cleveland Avenue North | Saint Paul, MN 55114
Phone (651) 659-9001 | (800) 972-6364 | Fax (651) 659-1379 | www.amengtest.com | AA/EEO
This document shall not be reproduced, except in full, without written approval from American Engineering Testing, Inc.
CONSULTANTS
·ENVIRONMENTAL
·GEOTECHNICAL
·MATERIALS
·FORENSICS
PAVEMENT CORE LOG
Jamaica Avenue Improvements – Cottage Grove, Minnesota
AET Project Number:28-20309
Core: B-7
Date Cored: June 2, 2020
Description:
Core Diameter: 4”
Total Core Height: 4.4”
Lift 1: 1.8”
Lift 2: 1.3”
Lift 3: 1.3”
Comments:
Possible chip seal at the surface.
Core generally has slight to
moderate stripping throughout.
550 Cleveland Avenue North | Saint Paul, MN 55114
Phone (651) 659-9001 | (800) 972-6364 | Fax (651) 659-1379 | www.amengtest.com | AA/EEO
This document shall not be reproduced, except in full, without written approval from American Engineering Testing, Inc.
CONSULTANTS
·ENVIRONMENTAL
·GEOTECHNICAL
·MATERIALS
·FORENSICS
PAVEMENT CORE LOG
Jamaica Avenue Improvements – Cottage Grove, Minnesota
AET Project Number:28-20309
Core: B-8
Date Cored: June 2, 2020
Description:
Core Diameter: 4”
Total Core Height: 5.6”
Lift 1: 2.0”
Lift 2: 1.6”
Lift 3: 2.0”
Downhole Bituminous Thickness:
7”
Comments:
Possible chip sealat the surface.
Lifts 1 and 2 contain slight stripping.
Lift 3 contains moderatestripping.
550 Cleveland Avenue North | Saint Paul, MN 55114
Phone (651) 659-9001 | (800) 972-6364 | Fax (651) 659-1379 | www.amengtest.com | AA/EEO
This document shall not be reproduced, except in full, without written approval from American Engineering Testing, Inc.
CONSULTANTS
·ENVIRONMENTAL
·GEOTECHNICAL
·MATERIALS
·FORENSICS
PAVEMENT CORE LOG
Jamaica Avenue Improvements – Cottage Grove, Minnesota
AET Project Number:28-20309
Core: B-9
Date Cored: June 2, 2020
Description:
Core Diameter:4”
TotalCore Height:5.”
Lift 1: 1.6”
Lift 2: 1.7”
Lift 3: 1.8”
Comments:
Possible chip seal at the surface.
Lift 1 contains slight stripping.
Lift 2 contains moderate stripping.
Lift 3 contains severe stripping
and large voids.
550 Cleveland Avenue North | Saint Paul, MN 55114
Phone (651) 659-9001 | (800) 972-6364 | Fax (651) 659-1379 | www.amengtest.com | AA/EEO
This document shall not be reproduced, except in full, without written approval from American Engineering Testing, Inc.
CONSULTANTS
·ENVIRONMENTAL
·GEOTECHNICAL
·MATERIALS
·FORENSICS
PAVEMENT CORE LOG
Jamaica Avenue Improvements – Cottage Grove, Minnesota
AET Project Number:28-20309
Core: B-10
Date Cored:June 2, 2020
Description:
Core Diameter:4”
TotalCore Height:5.”
Lift 1: 2.1”
Lift 2: 2.1”
Lift 3: 1.3”
Comments:
Possible chip seal at the surface.
Core contains moderate stripping
throughout.
550 Cleveland Avenue North | Saint Paul, MN 55114
Phone (651) 659-9001 | (800) 972-6364 | Fax (651) 659-1379 | www.amengtest.com | AA/EEO
This document shall not be reproduced, except in full, without written approval from American Engineering Testing, Inc.
CONSULTANTS
·ENVIRONMENTAL
·GEOTECHNICAL
·MATERIALS
·FORENSICS
PAVEMENT CORE LOG
Jamaica Avenue Improvements – Cottage Grove, Minnesota
AET Project Number:28-20309
Core: B-11
Date Cored:June 2, 2020
Description:
Core Diameter:4”
TotalCore Height:”
Bituminous Downhole
Thickness:
7”
Comments:
Possible chip seal at the surface.
Core contains severe stripping
throughout. Core crumbled during
coring operations.
550 Cleveland Avenue North | Saint Paul, MN 55114
Phone (651) 659-9001 | (800) 972-6364 | Fax (651) 659-1379 | www.amengtest.com | AA/EEO
This document shall not be reproduced, except in full, without written approval from American Engineering Testing, Inc.
Appendix B
Falling Weight DeflectometerField Exploration and Testing
Figure 2–Effective Subgrade R-Value Map
Appendix B
Falling Weight Deflectometer Field Exploration and Testing
AET Project No. 28-20309
B.1 PAVEMENT TESTING
The pavement structuralconditions at the site were evaluatednondestructively using Falling Weight Deflectometer
(FWD). The description of the equipment precedesthe Deflection Data and Analysis Resultsin this appendix.
B.2 EQUIPMENT DESCRIPTION
B.2.1 Dynatest 8000 FWD Test System
The FWD owned by AET isa Dynatest 8000 FWD Test System that consists of a Dynatest 8002 trailer and a third
generation control and data acquisition unit developed in 2003, called the Dynatest Compact15, featuring fifteen (15)
deflection channels.The new generation FWD, including a Compact15 System and a standard PC with the FwdWin
Field Program constitutes the newest, most sophisticated Dynatest FWD Test System, which fulfills or exceeds all
requirements to meet ASTM-4694Standards.Figure B1 provides a view of this equipment.
Figure B1Dynatest 8002FWD Test System
The FWD imposes a dynamic impulse load onto the pavement surface through a load plate. Total pulse is an
approximately half sine shape with a total duration typically between 25 to 30 ms. The FWD is capable of applying
a variety of loads to the pavement ranging from 1,500lbf (7 kN) to 27,000 ibf (120 kN)by dropping a variable weight
mass from different heights to a standard, 11.8-inch (300-mm) diameter rigid plate.
The drop weights and the buffers areconstructed so that the falling weight buffer subassembly may be quickly and
conveniently changed between falling masses of 440lbm (200 kg)for highways and 770 lbm (350 kg)for airports.
With the 440 lbm (200 kg) package for highways threedrop heights are used with the target loadof 6,000 lbf (27 kN)
at drop height 1, 9,000 lbf (40 kN) at drop height 2, and 12,000 lbf at drop height 3 (53 kN). The drop sequence
consists of twoseating drops from drop height 3 and 2repeat measurementsat drop height 1and 1 measurement at
drop height 2for flexible pavements and 2repeat measurementsat drop height 2 and 1 measurement at drop height 3
for rigid pavements. The data from the seating drops is not stored.
The FWD is equipped with a load cell to measure the applied forces and nine geophones or deflectors to measure
deflections up to 100 mils (2.5mm).The load cell is capable of accurately measuring the force that is applied
perpendicular to the loading platewith aresolution of 0.15 psi (1 kPa)or better. The force isexpressed in terms of
pressure, as a function of loading plate size.
Nine deflectorsat the offsets listed in the following table in the Long Term Performance Program(LTPP)
configuration are capable of measuring electronically discrete deflectionsper test, together with nine (9) separate
deflection measuring channels for recording of the data.One (1) of the deflectors measuresthe deflection of the
pavement surface through the center of the loading plate, while seven (7)deflectors arecapable of being positioned
behind the loading plate along the housingbar, up to a distance of 5ft(2.5 m) from the center of the loading plateand
one (1) being positioned in front of the loading plate along the bar.
DeflectorD9D1D2D3D4D5D6D7D8
Offset (in.)
-1208121824364860
Appendix B-Page 1of 3AMERICAN ENGINEERING TESTING, INC.
Appendix B
Falling Weight Deflectometer Field Exploration and Testing
AET Project No. 28-20309
Field testing is performed in accordance with the standard ASTM procedures as described in ASTM D 4695-96,
“Standard Guide for General Pavement Deflection Measurements” and the calibration of our equipment is verified
each year at the Long TermPavement Performance Calibration Center in Maplewood, MN.
B.2.2 Linear Distance and Spatial Reference System
Distance measuringinstrument (DMI) is a trailer mounted two phase encoder system. When DMI is connected to the
Compact15 it provides for automatic display and recording distance information in both English and metric units with
a 1 foot (0.3 meters) resolution and four percent accuracy when calibrated using the provided procedure in the Field
Program.
Spatial reference system is a Trimble ProXH Global Positioning System (GPS)that consists of fully integrated
receiver, antenna and battery unit withTrimble’s new H-Star™ technology to provide subfoot (30 cm) post-processed
accuracy.The External Patch antenna isadded to the ProXH receiver for the position of the loading plate. TheExternal
Patch antenna can be conveniently elevated with the optional baseball cap to preventany signal blockage.
B.2.3 Air and Pavement Temperature Measuring System
A temperature monitoring probe, for automatic recording of air temperature, is an electronic (integrated circuit)
sensing element in a stainless steel probe.The probe mounts on the FWD unit in a special holder with air circulation
and connects to the Compact15.A non-contact Infra-Red (IR) Temperature Transmitter, for automatic recording of
pavement surface temperature only, features an integrated IR-detector and digital electronics in a weather proof
enclosure. The IR transmitter mounts on the FWD unit in a special holder with air circulation and connects to the
Compact15. Both probe and IR transmitter have a resolution of 0.9 ºF (0.5 ºC) and accuracy within ±1.8ºF (1 ºC) in
the 0 to 158 ºF (-18 to +70ºC) range when calibrated usingtheprovided procedure.
B.2.4Camera Monitoring System
A battery operated independent DC-1908E multi-functional digital camera with a SD card is used for easy positioning
of the loading plate or recording of the pavement surface condition at the testing locations.
B.3 SAMPLINGMETHODS
At the project level, the testing interval is set at 0.1 mi. (maximum) or 10 locations per uniform section in the Outside
Wheel Path (OWP) = 2.5 ft ± 0.25 ft (0.76 m ± 0.08 m) for nominal 12 ft (3.7 m) wide lanes.Where a divided roadbed
exists, surveys will betaken in both directions if the project will include improvements in both directions.If there is
more than one lane in one direction the surveys will be taken in the outer driving lane versus the passing lane of the
highway.FWD tests are performed at a constant lateral offset down the test section.
B.4 QUALITY CONTROL (QC) AND QUALITY ASSURANCE (QA)
the relative calibration of the FWD deflection sensors is conducted
In addition to the annual reference calibration,
monthly but not toexceed 6 weeks during the months in which the FWD unit is continually testing.The DMI is also
calibrated monthly by drivingthe vehicle over a known distance to calculate thedistance scale factor.The accuracy
of the FWD air temperature and infra-red (IR) sensors arechecked on amonthly basis or more frequently if the FWD
operator observes “suspicious” temperaturereadings.
Some care in the placement of the load plate and sensors is takenby the survey crew, especially where the highway
surface is rutted or cracked,to ensure that the load plate layson a flat surfaceand thatthe load plate and all geophones
lie on the same side of any visible cracks. Liberal use of comments placed in the FWD data file at the time of data
collection is required. Comments pertaining to proximity to reference markers, bridge abutments, patches, cracks, etc.,
are all important documentation for the individual evaluating the data.
Scheduled preventive maintenance ensuresproper equipment operation and helps identify potential problemsthatcan
be corrected to avoid poor qualityor missing data that results if the equipment malfunctionswhile on site.The routine
and major maintenance procedures established by the LTPP are adopted and any maintenance has beendoneat the
end of the day after the testing is complete and become part of the routineperformed at the end of each test/travel day
and on days when no other work is scheduled.
Appendix B-Page 2of 3AMERICAN ENGINEERING TESTING, INC.
Appendix B
Falling Weight Deflectometer Field Exploration and Testing
AET Project No. 28-20309
B.5 DATA ANALYSISMETHODS
B.5.1 Inputs
The two-way AADT and HCADT are requiredto calculate the ESALs. The state average truck percent and truck type
distribution are used when HCADT is not provided.The as-built pavement information (layer type, thickness, and
construction year)are requiredand if not provided, GPR and/or coring and boring is needed.
B.5.2Adjustments
Temperature adjustment to the deflections measured on bituminous pavements is determined from the temperature
predicted at the middle depth of the pavement using the LTPP BELLS3 model that uses the pavement surface
temperature and previous day mean air temperature. The predicted middle depth temperature and the standard
temperature of 80 degrees Fahrenheit are used to calculate the temperature adjustment factor for deflection data
analysis. Seasonal adjustmentdeveloped by Mn/DOT is also used.
B.5.3Methods
For bituminous pavements, the deflection data were analyzed using the Mn/DOT method for determining the in-place
(effective) subgrade and pavement strength, as well as allowable axle loads for a roadway (Investigation 603) revised
in 1983 and automated with spreadsheet format in 2008. The Mn/DOT method uses Hogg Model for estimating the
subgrade modulus and the Effective GE Equation (Investigation 603) for estimating the effective GE of pavements.
The Mn/DOT method also uses the TONN method for estimating Spring Load Capacity and Required Overlay, as
described in the Mn/DOT publication “Estimated Spring Load-Carrying Capacity”.
For gravel roads, the deflection data were analyzed using the American Association of State Highway and
Transportation Officials’ (AASHTO) method for determining the in-place (effective) subgrade and pavement strength,
as well as allowable axle loads for a roadway as in the AASHTO Guide for Design of Pavement Structures, 1993.
For concrete pavements, the deflection data were analyzed using the FAA methods for determining the modulus of
subgrade reaction(k-value), effective elastic modulus of concrete slabs, load transfer efficiency (LTE) onapproach
and leaveslabsof a joint,slab support conditions (void analysis) and impulse stiffness modulus ratio (durability
analysis) as in the FAA AC 150/5370-11A, Use ofNondestructive Testing Devices in the Evaluation of Airport
Pavement, 2004.
B.6 TEST LIMITATIONS
B.6.1 Test Methods
The data derived through the testingprogram have been used to develop our opinions about the pavementconditions
at your site. However, because no testingprogram can reveal totally what is in the subsurface, conditions between test
locationsand at other times, may differ from conditions described in this report. The testingwe conducted identified
pavementconditions only at those points where we measured pavement surface temperature,deflections, andobserved
pavement surfaceconditions. Depending on the sampling methods and sampling frequency, every locationmay not
be tested, and some anomalieswhich are present in the pavementmay not be noted on the testing results.If conditions
encountered during construction differ from those indicated by our testing, it may be necessary to alter our conclusions
and recommendations, or to modify construction procedures, and the cost of construction may be affected.
B.6.2Test Standards
Pavementtesting is done in general conformance with the described procedures. Compliance with any other standards
referenced within the specified standard is neither inferred nor implied.
Appendix B-Page 3of 3AMERICAN ENGINEERING TESTING, INC.
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Date: 06/26/2020AET Project No. 28-20309
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File: 28-20309P-1.mxd Date: 06/26/2020
Appendix C
AET Project No. 28-20309
Ground Penetrating RadarField Exploration and Testing
GPR Plots
Appendix C
Ground Penetrating Radar Field Exploration and Testing
AET Project No. 28-20309
C.1 FIELD EXPLORATION
The pavement structural conditions at the site were evaluated nondestructively using Ground PenetratingRadar
(GPR). The description of the equipment precedesthe GPRData and Analysis Results in this appendix.
C.2EQUIPMENT DESCRIPTION
C.2.1 GSSI GPR Test System
The GPR test systemowned by AET isa GSSI Roadscan System that consists of a bumper-mounted, 2 GHz air-
coupled antenna and a SIR-20 control and data acquisition processor, featuring dual channels. The GPR processor,
including a SIR-20data acquisition system, wheel-mounted DMI (Distance Measuring Instrument), and a tough book
with the SIR-20 Field Program constitutes the newest, most sophisticated GSSI Test System, which fulfills or exceeds
all requirements to meet ASTM-4748, ASTM D-6087 Standards. Figure C1 provides a view of this equipment.
Figure C1 GSSI 2 GHz air-coupled GPR Test System
The GPR antennaemitsahigh frequency electromagnetic wave into the material under investigation. The reflected
energy caused by changes in theelectromagnetic properties within the material is detected by a receiver antenna and
recorded forsubsequent analysis.The 2 GHz air-coupled GPRis capable of collectingradar waveforms at more than
100 signals per second,allows for data to be collected at driving speeds along the longitudinal dimension of the
pavements or bridge decks with the antennas fixed at the rear or in front of the vehicle.
The antenna used for Roadscan isthe Horn antennaModel 4105 (2 GHz). The 2 GHz antenna is the current antenna
of choice for road survey because it combines excellent resolution with reasonable depth penetration(18-24 inches in
pavement materials). The data collection isperformed at normal driving speeds (45-55 mph), requiring no lane
closures nor causing traffic congestion.At this peed the 2 GHz antenna is capable of collecting data at 1-foot interval
(1 scan/foot).
The data were collected at a rate of about 1 vertical scans per foot.Each vertical scan consisted of 512samples and
the record length in time of each scan was 12nanoseconds. Filters used during acquisition were 300MHz high pass
and 5,000 MHz low pass.
In a GPR test, the antenna is moved continuouslyacross the test surface and the control unit collectsdata at a specified
distance increment.In this way, the data collection rate is independentof the scan rate. Alternatively, scanning can
beperformed at a constant rate of time, regardless ofthe scan distance. Single point scans can be performedas well.
Data is reviewed on-screen and inthe fieldto identify reflections and ensure properdata collection parameters.
Field testing is performed in accordance with the standard ASTM procedures as described in ASTM D 4695-96,
“Standard Guide for General Pavement Deflection Measurements”.
C.2.2 System Calibrations
Horn antenna processing is used to get the velocity of the radar energy in the material by comparing the reflection
strengths (amplitudes) from a pavement layer interface with a perfect reflector (a metal plate).Thecalibration scan is
obtained with the horn antenna placed over a metal plate at the same elevation as a scan obtained over pavement.
Appendix C-Page 1of 3AMERICAN ENGINEERING TESTING, INC.
Appendix C
Ground Penetrating Radar Field Exploration and Testing
AET Project No. 28-20309
The same setting for data collection is used for metal plate calibration. Fifteen seconds are need for jumpingup and
down on the vehicle’s bumper to collect the full range of motion for the vehicle’s shocks. The filename of raw
calibration fileis recorded.
Surveywheel is calibrated by laying out a long distance (> 50 feet) with tape measure.
C.2.3Linear Distance and Spatial Reference System
Distance measuringinstrument (DMI) is a trailer mounted two phase encoder system. When DMI is connected to the
SIR-20 it provides for automatic display and recording distance information in both English and metric units with a 1
foot (0.3 meters) resolution and four percent accuracy when calibrated using provided procedure in the Field Program.
Spatial reference system is a Trimble ProXH Global Positioning System (GPS) that consists of fully integrated
receiver, antenna and battery unit withTrimble’s new H-Star™ technology to provide subfoot (30 cm) post processed
accuracy.The External Patch antenna isadded to the ProXH receiver for the position of the loading plate. TheExternal
Patch antenna can be conveniently elevated with the optionalbaseball cap to preventany signal blockage.
C.2.4Camera Monitoring System
A battery operated independent DC-1908E multi-functional digital camera with a SD card is used for easy positioning
of the loading plate or of the pavement surface condition at the testing locations.
C.3SAMPLINGMETHODS
At the project level, the testing interval is set at 12 scans per foot in the Outside Wheel Path (OWP) = 2.5 ft ± 0.25 ft
(0.76 m ± 0.08 m) for nominal 12 ft (3.7 m) wide lanesat a survey speed of approximately 10 mph.Where a divided
roadbed exists, surveys will betaken in both directions if the project will include improvements in both directions.If
there is more than one lane in one direction the surveys will be taken in the outer driving lane (truck lane) versus the
passing lane of the highway.GPRtests are performed at a constant lateral offset down the test section.When GPR
tests are performed on bridge decks, multiple survey lines are followed transversely at 2-foot spacing between survey
lines.
At the network level, GPRtests on one scan per foot are set to be able to collect data on pavements at driving speeds,
without statistically compromising the quality of the data collected. If GPR tests are for the in situ characterization of
material GPR data will be collectedat two scan per foot at slower driving speeds.
C.4QUALITY CONTROL (QC) AND QUALITY ASSURANCE (QA)
Beside the daily metal plate calibration the DMI is also calibrated monthly by driving the vehicle over a known
distance to calculate thedistance scale factor.The GPR will be monitored in real time in the data collection vehicle
to minimize data errors. The GPR units will be identified with a unique number and that number will accompany all
data reported from that unit as required in the QC/QA plan.
Scheduled preventive maintenance ensuresproper equipment operation and helps identify potential problemsthat can
be corrected to avoid poor qualityor missing data that results if the equipment malfunctionswhile on site.The routine
and major maintenance procedures established by the LTPP are adopted and any maintenance has beendoneat the
end of the day after the testing is complete and become part of the routineperformed at the end of each test/travel day
and on days when no other work is scheduled.
To insure quality data, the GPR assessments only took place on dry pavement surfaces, and data was collected in each
wheel path.
C.5DATA ANALYSISMETHODS
C.5.1 Data Editing
Field acquisition is seldom so routine that noerrors, omissions or data redundancy occur. Data editing encompasses
issues such as data re-organization, data filemerging, data header or background information updates, repositioning
and inclusion of elevation information withthe data.
C.5.2Basic Processing
Appendix C-Page 2of 3AMERICAN ENGINEERING TESTING, INC.
Appendix C
Ground Penetrating Radar Field Exploration and Testing
AET Project No. 28-20309
Basic data processing addresses some of the fundamental manipulations applied to data to make a more acceptable
product for initial interpretation and data evaluation. In most instances this type of processing is already applied in
real-time to generate the real-time display. The advantage of post survey processing is that the basic processing can
be done more systematically and non-causal operators to remove or enhance certain features can be applied.
The Reflection Picking procedure is used to eliminate unwanted noise, detects significant reflections,and records the
corresponding time and depth. It uses antenna calibration file data to calculate the radar signal velocity within the
pavement.
C.5.3Advance Processing
Advanced data processing addresses the types of processing which require a certain amount of operator bias to be
applied and which will result in data which are significantly different from the raw information which were input to
the processing.
C.5.4Data Interpretation
The EZ Tracker Layer Interpretation procedure uses the output from the first step to map structural layers and calculate
the corresponding velocities and depths.
C.6 TEST LIMITATIONS
C.6.1 Test Methods
The data derived through the testingprogram have been used to develop our opinions about the pavementconditions
at your site. However, because no testingprogram can reveal totally what is in the subsurface, conditions between test
locationsand at other times, may differ from conditions described in this report. The testingwe conducted identified
pavementconditions only at those points where we measured pavement thicknesses andobserved pavement surface
conditions. Depending on the sampling methods and sampling frequency, every locationmay not be tested, and some
anomalieswhich are present in the pavementmay not be noted on the testing results.If conditions encountered during
construction differ from those indicated by our testing, it may be necessary to alter our conclusions and
recommendations, or to modify construction procedures, and the cost of construction may be affected.
B.6.2Test Standards
Pavementtesting is done in general conformance with the described procedures. Compliance with any other standards
referenced within thespecified standard is neither inferred nor implied.
C.7SUPPORTING TEST METHODS
C.7.1 Falling Weight Deflectometer (FWD)
If the pavement layer moduli and subgrade soil strengthare desiredthe deflectiondata are collected using a Dynatest
8000 FWD Test System that consists of a Dynatest 8002 trailer and a third generation control and data acquisition unit
developed in 2003, called the Dynatest Compact15, featuring fifteen (15) deflection channels. The new generation
FWD, including a Compact15 System and a standard PC with the FwdWin field Program constitutes the newest, most
sophisticated Dynatest FWD Test System, which fulfills or exceeds all requirements to meet ASTM-4694, ASTM D-
4695 Standards.The system provides continuous dataat pre-setspacing.
C.7.2Soil Boring/Coring Field Exploration
If both pavement thicknesses and subgrade soil types and conditions are desired the shallow coring/boring and
sampling is used. The limited number of coring/boring is necessary to verify the GPR layer thickness data.
C.7.3Pavement Surface Condition Survey
The type and severity of pavement distress influence the deflection response for a pavement.Therefore, GPR
operators record any distress located from about 1 ft (0.3m)in front ofvehicleto about 30 ft (9 m)ahead. This
information isrecorded in theFWD file using the comment line in the field program immediately following the test.
Appendix C-Page 3of 3AMERICAN ENGINEERING TESTING, INC.
St90th
90th St S
NB Base Outside
NB Base Inside
Rd.DouglasPt.E.
GPR Distance (mi)
Ground Penetrating Radar Pavement Thickness Survey
NB BP Outside
1
NB BP Inside
B
0.000.050.100.150.200.25
0.0
-2.0-4.0-6.0-8.0
-10.0-12.0-14.0-16.0-18.0
Depth (in)
St80th
80th st
SAve.Janero
4
B
SAve.Isle
NB Base Outside
SJasmineAve
NB Base Inside
GPR Distance (mi)
3
B
STr.Hillside
Ground Penetrating Radar Pavement Thickness Survey
NB BP Outside
2
NB BP Inside
B
St90th
0.000.200.400.600.801.00
0.0
-2.0-4.0-6.0-8.0
-10.0-12.0-14.0-16.0-18.0
Depth (in)
NB Base Outside
SBlvd.Indian
6
B
NB Base Inside
SSt.75th
GPR Distance (mi)
NB BP Outside
Ground Penetrating Radar Pavement Thickness Survey
5
B
NB BP Inside
SSt.80th
0.00.10.20.30.40.50.60.70.80.91.0
0.0
-2.0-4.0-6.0-8.0
-10.0-12.0-14.0-16.0-18.0
Depth (in)
St90th
SB Base Outside
11
B
SB Base Inside
Rd.DouglasPt.E.
GPR Distance (mi)
SB BP Outside
Ground Penetrating Radar Pavement Thickness Survey
SB BP Inside
0.000.050.100.150.200.25
0.0
-2.0-4.0-6.0-8.0
-10.0-12.0-14.0-16.0-18.0
Depth (in)
St80th
SAve.Janero
8
B
SB Base Outside
SAve.Isle
9
B
SB Base Inside
SJasmineAve
GPR Distance (mi)
STr.Hillside
SB BP Outside
Ground Penetrating Radar Pavement Thickness Survey
10
B
SB BP Inside
St90th
0.00.20.40.60.81.0
0.0
-2.0-4.0-6.0-8.0
-10.0-12.0-14.0-16.0-18.0
Depth (in)
SBlvd.Indian
SB Base Outside
SB Base Inside
SSt.75th
GPR Distance (mi)
7
B
SB BP Outside
Ground Penetrating Radar Pavement Thickness Survey
SB BP Inside
80thSt.
0.00.10.20.30.40.50.60.70.80.91.0
0.0
-2.0-4.0-6.0-8.0
-10.0-12.0-14.0-16.0-18.0
Depth (in)
Report of Geotechnical Exploration
Jamaica Avenue Improvements -Cottage Grove, MNAMERICAN
July 2, 2020ENGINEERING
AET Report No. 28-20309TESTING, INC.
Appendix D
Geotechnical Report Limitations and Guidelines for Use
Appendix D
Geotechnical ReportLimitations and Guidelines for Use
AET Project. 28-20309
D.1 REFERENCE
This appendix provides information to help you manage your risks relating to subsurface problems which are caused by
1
, of which, we
construction delays, cost overruns, claims, and disputes. This information was developed and provided by ASFE
are a member firm.
D.2 RISK MANAGEMENT INFORMATION
D.2.1 Geotechnical Services are Performed for Specific Purposes, Persons, and Projects
Geotechnical engineers structure their services to meet the specific needs of their clients. A geotechnical engineering study
conducted for a civil engineer may not fulfill the needs of a construction contractor or even another civil engineer.Because each
geotechnical engineering study is unique, each geotechnical engineering report is unique, prepared solely for the client. No one
except you should rely on your geotechnical engineering report without first conferring with the geotechnical engineer who
prepared it. Andno one, not even you, should apply the report for any purpose or project except the one originally contemplated.
D.2.2 Read the Full Report
Serious problems have occurred because those relying on a geotechnical engineering report did not read it all. Do not rely on an
executive summary. Do not read selected elements only.
D.2.3 A Geotechnical Engineering Report is Based on A Unique Set of Project-Specific Factors
Geotechnical engineers consider a fewunique, project-specific factors when establishing the scope of a study. Typically factors
include: the client’s goals, objectives, and risk management preferences; the general nature of the structure involved, its size, and
configuration; the location of the structure on the site; and other planned or existing site improvements, such as access roads,
parking lots, and underground utilities. Unless the geotechnical engineer who conducted the study specifically indicates otherwise,
do not rely on a geotechnical engineering report that was:
not prepared for you,
not prepared for your project,
not prepared for the specific site explored, or
completed before important project changes were made.
Typical changes that can erode the reliability of an existing geotechnical engineering report include those that affect:
the function of the proposed structure, as when it’s changed from a parking garage to an office building, or from a light
industrial plant to a refrigerated warehouse,
elevation, configuration, location, orientation, or weight of the proposed structure,
composition of the design team, or
project ownership.
As a rule, always inform your geotechnical engineer of project changes, even minor ones, and requestan assessment of their
impact.Geotechnical engineers cannot accept responsibility or liability for problems that occur because their reports do not
consider developments of which they were not informed.
D.2.4 Subsurface Conditions Can Change
A geotechnical engineering report is based on conditions that existed at thetime the study was performed. Do not rely on a
geotechnical engineering report whose adequacy may have been affected by: the passage of time; by man-made events, such as
construction onor adjacent to the site; or by natural events, such as floods, earthquakes, or groundwater fluctuations. Always
contact the geotechnical engineer before applying the report to determine if it is still reliable. A minor amount of additional testing
or analysis could prevent major problems.
1Geoprofessional Business Association,1300 Piccard Drive, LL14,Rockville, MD20850
Telephone: 301/565-2733: www.geoprofessional.org
Appendix D–Page1of 2AMERICAN ENGINEERING TESTING, INC
Appendix D
Geotechnical ReportLimitations and Guidelines for Use
AET Project. 28-20309
D.2.5 Most Geotechnical Findings Are Professional Opinions
Site exploration identified subsurface conditions only at those points where subsurface tests are conducted or samples are taken.
Geotechnical engineers review field and laboratory data and then apply their professional judgment to render an opinion about
subsurface conditions throughout the site. Actual subsurface conditions may differ, sometimes significantly, from those indicated
in your report. Retaining the geotechnical engineer who developed your report to provide construction observation is the most
effective method of managing the risks associated with unanticipated conditions.
D.2.6 A Report’s Recommendations Are Not Final
Do not over relyon the construction recommendations included in your report. Those recommendations are not final, because
geotechnical engineers develop them principally from judgment and opinion. Geotechnical engineers can finalize their
recommendations only by observing actual subsurface conditionsrevealed during construction. The geotechnical engineer who
developed your report cannot assume responsibility or liability for the report’s recommendations if that engineer does not perform
construction observation.
D.2.7 A Geotechnical Engineering Report Is Subject to Misinterpretation
Other design team members’ misinterpretation of geotechnical engineering reports has resulted in costly problems.Lower that risk
by having your geotechnical engineer confer with appropriate members of the design team after submitting the report. Also retain
your geotechnical engineer to review pertinent elements ofthe design team’s plans and specifications. Contractors can also
misinterpret a geotechnical engineering report. Reduce that risk by having your geotechnical engineer participate in prebid and
preconstruction conferences, and by providing construction observation.
D.2.8 Do Not Redraw the Engineer’s Logs
Geotechnical engineers prepare final boring and testing logs based upon their interpretation of field logs and laboratory data. To
prevent errors or omissions, the logs included in a geotechnical engineering report should never be redrawn for inclusion in
architectural or other design drawings. Only photographic or electronic reproduction is acceptable butrecognizesthat separating
logs from the report can elevate risk.
D.2.9Give Contractors a Complete Report and Guidance
Some owners and design professionals mistakenly believe they can make contractors liable for unanticipated subsurface conditions
by limiting what they provide for bid preparation. To help prevent costly problems, give contractors the complete geotechnical
engineering report, but preface it with a clearlywritten letter of transmittal.In the letter, advise contractors that the report was not
prepared for purposes of bid development and that the report’s accuracy is limited; encourage themto confer with the geotechnical
engineer who prepared the report (a modest fee may be required) and/or to conduct additional study to obtain the specific types of
information they need orprefer. A prebid conference can also be valuable. Be sure contractors have sufficient time to perform
additional study. Only then might you be ableto give contractors the best information available to you, while requiring them to at
least share some of the financial responsibilities stemmingfrom unanticipated conditions.
D.2.10Read Responsibility Provisions Closely
Some clients, design professionals, and contractors do not recognize that geotechnical engineering is far less exact than other
engineering disciplines. This lack of understanding has created unrealistic expectations that have led to disappointments, claims,
and disputes. To help reduce the risk of such outcomes, geotechnical engineers commonly include a variety of explanatory
provisions in their report. Sometimes labeled “limitations” many of these provisions indicate where geotechnical engineers’
responsibilities begin and end, to help others recognize their own responsibilities and risks. Read these provisions closely. Ask
questions. Your geotechnical engineer should respond fully and frankly.
D.2.11 Geoenvironmental Concerns Are Not Covered
The equipment, techniques, and personnel used to perform a geoenvironmental study differ significantly from those used toperform
a geotechnical study. For that reason, a geotechnical engineering report does not usually relate any geoenvironmental findings,
conclusions, or recommendations; e.g., about the likelihood of encountering underground storage tanks or regulated contaminants.
Unanticipated environmental problems have ledto numerous project failures. If you have not yet obtained your own
geoenvironmental information, ask your geotechnical consultant for risk management guidance.Do not rely on an environmental
report prepared for someone else.
Appendix D–Page2of 2AMERICAN ENGINEERING TESTING, INC