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K:\012165-000\Admin\Contract\175th Street Concept\WSB 175th Street Supplemental Agreement 12 4 18.docx
December 4, 2018
Mr. Alex Jordan, PE
Assistant City Engineer
City of Lakeville
20195 Holyoke Avenue
Lakeville, MN 55044
Re: 175th Street Widening Study
Proposal for Engineering Services:
Preliminary Study for Road Improvements
Dear Mr. Jordan:
On behalf of WSB, we are pleased to submit this proposal to provide this Supplemental Agreement
to provide professional engineering services as they relate to a study of improvements for the City
of Lakeville’s (City) 175th Street, south of and adjacent to Orchard Lake.
BACKGROUND INFORMATION
After a mid-October informative meeting to discuss the 175th Street Corridor, the City has requested
WSB to provide a proposal to evaluate the feasibility of widening and realigning 175 th Street within
the general confines of the areas highlighted in Figure 1. Currently, 175 th Street has a useable
roadway width of approximately 20-ft, see Figure 2. The existing embankment of both the north
side (lake side) and the south side (single family homes) of the road are known to be steep,
approximately 1:1 (horizontal: vertical), see Figure 2. Property owners in the area have identified
concerns with roadway proximity to the lake, roadway width being insufficient to accommodate two-
way traffic and pedestrian safety in the area. While this segment of 175th Street is not currently on
the City’s MSAS system, it is likely 172nd Street/175th Street/Judicial Road/168th Street will be added
in the future.
Figure 1: Project Location
(https://www.google.com/maps)
Mr. Alex Jordan
December 4, 2018
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The existing roadway embankment has been subject to sloughing on the lake side and has
undergone several maintenance and repair projects over its recent history. It is known that existing
roadway does not meet MnDOT State Aid Standards for criteria such as clear zone s and traffic
barrier requirements.
Figure 2: Existing Roadway Cross Section, 175th Street
PROJECT UNDERSTANDING
To accommodate the proposed widening and realignment of the road, WSB presented various
roadway sections, alignment and retaining wall options during preliminary discussions with City.
Several general geotechnical assumptions were established by WSB and agreed upon by City staff
to narrow down viable options for the project corridor. As a result, three options will be eva luated
as a part of this preliminary evaluation:
1. Option 1: Includes reclamation of the roadway, drainage improvements to the area
(possibly including, but not limited to: concrete curb and gutter, storm sewer, catch basin
inlets, etc.) and installation of a guard rail along the lake side of the roadway. The existing
roadway would remain in its current location and generally speaking, would be maintained
at its current width, except where guard rail placement may dictate otherwise.
2. Option 2: Includes reclamation of the roadway, drainage improvements to the area
(possibly including, but not limited to: concrete curb and gutter, storm sewer, catch basin
inlets, etc.) and installation of a guard rail along the lake side of the roadway and an
evaluation as to the feasibility of installing a sheet pile wall along the lake side of the
roadway to stabilize the existing roadway embankment. Typically, these walls require
moderately good soil parameters to be a feasible option. Most likely the in-situ soils along
the lake are very poor, and following the geotechnical evaluation of the project corridor,
may be eliminated as a viable alternative.
The existing roadway would remain in its current location and generally speaking, would
be maintained at its current width, except where guard rail placement may dictate
otherwise.
North: Lake Side South: Single Family Homes
20’-0” +/- Roadway
Mr. Alex Jordan
December 4, 2018
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3. Option 3: Includes reclamation of the existing roadway, widening of the roadway section
to include a 20-foot wide roadway section (as measured from face-of-curb to face-of-curb)
paved concrete clear zones as measured from the back-of-curb (4-feet on the lake side, 2-
feet on the single family home side), drainage improvements to the area (possibly
including, but not limited to: concrete curb and gutter, storm sewer, catch basin inlets, etc .)
and installation of retaining wall system s along both sides of the roadway. This Option will
also include an evaluation of ornamental fence costs for the retaining wall system proposed
along the south side of the roadway and a barrier atop the retaining wall along the north
side of the roadway. Option 3 will not meet State Aid design requirements but can be
considered for local roadway improvements not utilizing State Aid funds to construct. This
will include an evaluation of:
a. Cast-in-place (CIP) concrete retaining wall. This is the preferred option, as it
provides the most durable wall against the harsh lake elements; it also provides
an alternative of a vehicle barrier (TL-2) for 175th Street’s low speed environment.
The CIP’s foundation (i.e., spread footing vs. piles) was an unknown during the
discussions, however, it is most likely this type of retaining wall will require a deep
foundation (pile) and not a spread footing, even for the moderate wall height of
about 8-ft.
Typically, these deep foundations would be comprised of driven piles, however
with houses not more than 50-ft from proposed pile driving operations, vibrations
will likely be a significant issue. An alternative to driven piles would be an auger
pile (drilled or screw), and this will be discussed further during the geotechnical
study.
b. Residence side retaining walls. Investigation of the topography of the area to the
south of 175th Street shows the locale to be quite varied in elevation, with lowlands
to the project’s western and eastern extents, and significantly higher areas near
the middle of the project (see Figure 2). Several wall types are possible along this
side of the road, since the harsh environment of the lake does not need to be
considered. Each wall type is very dependent upon the findings of the
geotechnical study, and has its pros and cons. Wall selection will be the focus of
Tasks 2 & 3.
i. Precast Modular Block Wall (PMBW ). Depending on the geotechnical
evaluation, this wall type could be a viable option for shorter wall heights.
Generally, these walls do not require significant in-situ soil modifications
for their foundations but do require a moderate length of excavation behind
the wall for the placement of the wall’s internal soil reinforcement straps,
see Figure 3. These walls are an excellent option for built -up areas but
are not always a good choice for areas with large differences in existing to
proposed elevation, such as those areas near the project’s center, which
would require additional temporary excavation bracing (e.g., sheet pile
wall) far behind the actual front face of the new wall.
Mr. Alex Jordan
December 4, 2018
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Figure 3: PMBW
ii. C-I-P wall. Same wall type as the preferred alternative for the lake side
wall. Similar to the PMBW wall, this also requires significant excavation
behind the wall in order to provide the backfill as required by MnDOT
Standard Plans, see Figure 4. Soil parameters encountered along this
side may not be all that much different than those encountered at the lake
side, and as such, this wall may also require a deep foundation (piles),
where driving piles very close to a house will certainly be a hindrance in
implementing this option.
Figure 4: C-I-P Wall
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December 4, 2018
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iii. Anchored wall. There are several types of anchored retaining walls, but
generally consist of a system shown in Figure 5, where the face of the wall
is tied to soil anchors that are permanently embedded into the soil behind
the wall. This wall type would most likely have much less vibration than
that required for driving a typical pile but does have other considerations
such as existing or proposed utilities that may be in the way of the anchors.
This wall type could be used in most locations.
Figure 5: Anchored Wall Detail
Several soil borings (see Task 2) will be obtained from the roadway corridor, only (as overhead
utilities exist along both sides of the roadway), in preparation of a geotechnical study, which will
further discuss and elaborate the wall types noted above an d select a wall type based on the
previously noted pros/cons of each wall.
c. Figure 6 illustrates the roadway section to be considered with Option 3, which
incorporates: a horizontal alignment shift of approximately 5-ft away from the lake
(to avoid impacts to this DNR watercourse); a vertical profile raise of approximately
18-in; a 4-ft clear zone to the lake side behind back of curb; and a 2-ft clear zone
behind back of curb to the single family home side.
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December 4, 2018
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Figure 6: Typical Roadway Section
PROJECT UNDERSTANDING
WSB assumes two coordination meetings with the City to review the p roject findings and evaluate
a draft version of the project study and to gather any additional feedback the City have prior to
finalizing the work.
Final deliverables will include:
• A geotechnical study of the various wall types based on several soil borings within the
roadway throughout the corridor.
• A conceptual plan/profile layout for each of the proposed options showing proposed
retaining wall locations/types (where applicable) and guard rail.
• An opinion of probable cost for each of three the proposed roadway improvements which
will be done at a planning-level.
• A decision matrix for each of the three options being considered.
SCOPE OF WORK
WSB’s project scope and proposed tasks are based on our understanding of the project. The
following approach procedures are organized as the project will progress and represents WSB’s
scope of work that can be used for contractual purposes. Each description includes a reference to
the corresponding task numbers on the fee estimate.
Task 1 – Project Management
Throughout the project, WSB’s Project Manager, Monica Heil, will actively manage the work
tasks to adhere to both the proposed schedule and budget, providing overall project oversight,
and provide day-to-day management of the project. She will communicate as necessary with
the City to meet the goals and expectations of the project. Management activities include
communication and coordination of the tasks with the City and sub -consultant efforts, and
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December 4, 2018
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preparation of invoices. Additional duties include atte ndance at and preparation of agendas,
minutes, and exhibits for the project meetings.
Task 2 – Additional Topographic Survey Data Collection
WSB will collect additional topographic survey information along the south side of the roadway,
within the single family properties. Additional topographic survey information to be collected
includes: slopes, vegetation, building structures, existing private retaining walls and any iron
monumentation that can be located on the properties. If available, found property corners will
be used to generate a Right of Way Map for use when determining property impacts associated
with the improvements.
Task 3 – Geotechnical Study
The WSB Team will include Braun Intertec (Braun). Braun will collect soil borings at the project
site. Braun will conduct a geotechnical investigation for the purposes of determining the soil
parameters for retaining wall selection. Braun will also coordinate all traffic control associated
with temporary road closures necessary to complete the boring work. Due to various site
access restrictions, including overhead utilities along both sides of the roadway, Braun will
complete all drilling within the roadway. As a result, the report may produce slightly diff erent
results than if the borings were performed along the lakeside embankment.
All boreholes will be sealed per Minnesota Department of Health requirements. The work will
require traffic control along with temporary roadway closures to obtain the borings. A copy of
the proposal submitted by Braun is attached.
Task 4 – Retaining Wall Evaluation
After the geotechnical analysis has been complete, WSB (with input from the City) will select
the most feasible retaining wall layout along the corridor. For the lake side, given that the
existing and proposed elevation does not vary significantly, only one wall type will be selected.
For the residence side, it may be a mixture of wa ll types based on the surrounding area’s
changing characteristics. For cost reasons, this will be limited to two (2) types of retaining walls
(i.e., C-I-P concrete wall, and PMBW). Ultimately though, there may only be one option
recommended by Braun.
Task 5 – Roadway Layout
WSB will prepare cost estimates associated street improvements for each of the three options.
Street improvements will include grading, excavation, a new roadway section, storm sewer
improvements and concrete curb and gutter, the type of which may vary between options.
Task 6 – Opinion of Probable Cost
Using the final concept layouts, WSB will complete high-level Opinion of Probable Costs, with
associated construction costs, such as concrete barriers, guard rails, ornamental metal railings,
clear zone pavement and storm sewer.
In order to provide an accurate Opinion of Probable Cost, items, quantities, and prices will be
determined through the use of existing plans, observed defects or deterioration, previous
project experience, and engineering judgement; not all items will be reported. Variations from
actual project costs will result from additional unforeseen factors such as, but are not limited
to, design exceptions, value engineering, utility relocation, and environmental imp acts.
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December 4, 2018
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Task 7 – Decision Matrix
Using the final recommended concept layouts, WSB will complete a decision matrix detailing
the three options considered and providing recommendations for the improvements.
Task 8 – Meetings
WSB will attend and assist in facilitating the following meetings:
• Two (2) meetings with City Staff to review findings and the concept layout and gather any
additional feedback the City may have prior to finalizing the final deliverables.
ASSUMPTIONS
WSB assumes that the City will coordinate all necessary right of entries with adjacent property
owners to facilitate the topographic survey data collection, and also the temporary road closure
associated with the geotechnical evaluation.
SCHEDULE
WSB will commence work on this project once we are authorized to proceed, and proposes the
following schedule:
Geotechnical Evaluation and Topographic Survey Data Collection .... December-January 2018
Retaining Wall Evaluations ................................................ February 2019
Roadway Layout, OPC and Draft Decision Matrix Delivered to the City .................. March 2019
Final Recommendations Delivered to the City ....................................................... April 2019
PROPOSED FEE
WSB & Associates will provide the services as outlined in the Scope of Work. Our budget was
developed based on our understanding of the scope and experience with past reconstruction
projects in the area. A summary of the costs for each phase of the project is as follows:
TASK DESCRIPTION FEE
1 PROJECT MANAGEMENT $ ................................................... 3,286.00
2 SURVEY/DATA COLLECTION $...................................................3,728.00
3 GEOTECHNICAL EVALUATION $.................................................13,230.00
4 RETAINING WALL EVALUATION $.................................................11,584.00
5 ROADWAY DESIGN $ ................................................... 2,374.00
6 OPINION OF PROBABLE COST $ ................................................... 1,688.00
7 DECISION MATRIX $ ................................................... 1,310.00
8 MEETINGS $ ................................................... 2,074.00
TOTAL PROPOSED FEE $ 39,274.00
We propose to complete Tasks 1 through 8 as indicated on a not-to-exceed fee of $39,274.00.
Task 3 does include the traffic control costs associated with the boring work within the roadway
corridor. If additional work outside of the above described scope is determined necessary, it will
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December 4, 2018
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proceed only after City approval. This additional work would be billed on an hourly basis in
accordance with WSB’s current Rate Schedule.
The proposed scope and fee presented herein represents our complete understanding of the
project based on site visits and discussions with City staff.
If you have any questions or concerns, please feel free to contact me at 952-737-4675. Once
again, we appreciate the opportunity to submit this proposal and look forward to working with you
and your staff.
Sincerely,
WSB & Associates, Inc.
Monica Heil, PE
Sr. Project Manager
Attachments
ACCEPTED BY:
City of Lakeville
By:
Douglas P. Anderson, Mayor
Date:
Attest:
Charlene Friedges, City Clerk
Task Description
1
1.1 Project Management 8 10 4 22 $3,286.00
1.2 Survey / Data Collection 6 16 22 $3,728.00
1.3 Geotechnical Study (Braun Intertec)Lump Sum $13,230.00
1.4 Retaining Wall Design 2 52 26 80 $11,584.00
1.5 Roadway Design 2 4 12 18 $2,374.00
1.6 Opinion of Probable Cost 8 4 12 $1,688.00
1.7 Decision Matrix 2 4 2 2 10 $1,310.00
1.8 Meetings 4 4 6 14 $2,074.00
Task 1 Total Estimated Hours and Fee 18 78 14 32 18 2 16 178 $39,274.00
Average Hourly Billing Rate 163.00 147.00 128.00 139.00 128.00 70.00 185.00
TOTAL PROJECT COST $39,274.00
Estimate of Cost
City of Lakeville
Professional Engineering Services
175th Street Concept
Estimated Hours
Shannon
HeitmannDan Flitte Mitch Hatcher Brad Robinson
Structural Senior
Project Manager CostTotal Hours
Monica Heil
Senior Project
Manager
Preliminary Design
Two-Person
Survey Crew
Administrative
Assistant
Tabitha Walsh
Project
Engineer
Engineering
Specialist
Project
Engineer