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TH 7 at Louisiana Avenue Interchange

Value Engineering Study Report SP 2706-226

August 10-13, 2010

HDR Engineering, Inc. 1001 SW 5th Avenue

Suite 1800 Portland, OR

(503) 423-3700

Disclaimer The information contained in this report is the professional opinions of the team members during the VE Study. These opinions were based on the information provided to the team at the time of the study. As the project continues to develop, new information will become available, and this information will need to be evaluated on how it may affect the recommendations and findings in this report. All costs displayed in the report are based on best available information at the time of the study and unless otherwise noted are in current year dollars.

TH 7 at Louisiana Avenue Interchange Table of Contents – TOC.1 Value Engineering Study Report Date: August 10-13, 2010

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Executive Summary Introduction Project Overview Project Issues Project Analysis VE Study Results Implementation Strategies Implementation of Recommendations VE Team Members

Project Description Proposed Project Existing Conditions Project Purpose and Need Scope of the Value Engineering Study Constraints and Controlling Decisions Information Provided to the VE Team

Project Analysis Project Issues Cost Model Functional Analysis FAST Diagram Performance Attributes Performance Attribute Matrix Value Matrix

Idea Evaluation Introduction Evaluation Process Deposition of Ideas Idea Evaluation Form

Recommendations Introduction Summary of VE Recommendations Implementation Strategies VE Recommendation Approval Design Considerations Individual Recommendations 1a-5b VE Validations 1-3

Appendix Value Engineering Pre-VE Study Value Engineering Job Plan Value Metrics Reporting Agenda Meeting Attendees VE Report Out VE Recommendation Approval Form

TH 7 at Louisiana Avenue Interchange Table of Contents – TOC.2 Value Engineering Study Report Date: August 10-13, 2010

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TH 7 at Louisiana Avenue Interchange Executive Summary – ES.1 Value Engineering Study Report Date: August 10-13, 2010

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Introduction This Value Engineering (VE) Study Executive Summary provides an overview of the project, key findings, and the recommendations developed by the VE Team. Detailed documentation and exhibits of the study’s analysis are provided in the VE Study Report.

A VE Study, sponsored by the City of Saint Louis Park, Minnesota and facilitated by HDR Engineering, Inc., was conducted for the improvements to the TH 7 at Louisiana Avenue Interchange project. The study was conducted during the planning phase, and the project has a scheduled letting of November 2011. This VE Study was conducted from August 10-13, 2010.

Project Overview The purpose of this project is to remove the existing at-grade intersection of TH 7 and Louisiana Avenue in St. Louis Park and to replace it with a grade separated interchange. The improvements will include pedestrian and bicycle paths along with reconfiguration of local frontage roads to improve mobility to the TH 7 corridor and Louisiana Avenue. This project is essential for meeting transportation and safety needs of the region and is anticipated to reduce conflicts to the traveling public.

Louisiana Avenue serves as a vital north-south corridor through the City, carrying 10,000 to 15,000 vehicles per day at this location. TH 7 carries 35,000 to 40,000 vehicles per day through this intersection. The current configuration of the frontage roads to TH 7 and the heavy traffic generated by nearby businesses add to the congestion.

Traffic studies show that this project is necessary for future redevelopment activities including overall mixed use development and higher density housing, a future light rail transit (LRT) station, and expansion of the nearby hospital. In addition, transit riders, bicyclists and pedestrians will benefit from improved mobility to jobs, housing, and other destinations.

Project Issues The following are some of the issues, concerns, and possible constraints associated with this project:

Avoid impacts to the Louisiana Oaks apartment complex and Sam’s Club Pedestrian and bike traffic must be accommodated during construction Right in – Right out east of Louisiana Ave. will be closed as part of this project March 2012 funding obligation date – there is a potential for a 1-year extension with prior

approval by Met Council Minimize excavation (high potential of contaminated soils) Environmental Assessment (EA) process is just starting – the draft document is scheduled

to be out by October 2010 Any impacts to the flood plain will need to be mitigated – no net increase in 100-year flood

elevation Avoid impact to 4f properties.


Project Analysis

The VE Team analyzed the project using the VE Job Plan and associated tools.

Using functional analysis and Functional Analysis System Technique (FAST) diagramming, the team defined the basic function of this project as Reduce Conflict, Improve Mobility, and Create Access. Key secondary functions include Remove Access and Stage Construction. Analysis of the functions intended to be performed by the project helped the team focus on the purpose and need of the project and, consequently, how to craft recommended concepts that would provide the required functions.

Specific performance criteria were developed and agreed upon by the VE and Project Teams. These criteria were weighted using a paired comparison technique, which was then used to evaluate ideas.

VE Study Results

The VE Team generated 48 different ideas for this project. These concepts were compared against the baseline that was developed by the Project Team. The concepts that performed the best were further developed by the VE Team.

From these ideas the VE Team developed 8 recommendations resulting in a net cost savings of $3.9 million to $5.1 million and an overall performance improvement of +7 to +11%.

The individual recommendations are summarized below:

1a. Ground Improvements $2.4 M 9% Use ground improvement technologies such as deep soil mixing, stone columns or other types instead of excavating muck from under TH 7.

1b. Lightweight Fill $2.2 M -2% Use lightweight fill such as EPS Geofoam or shredded tires instead of excavating muck from under TH 7.

1c. Pile Supported Fill $2.5 M 6% Use pile supported embankment instead of excavating muck from under TH 7.

2. Reinforced Slopes $1.1 M 7% Replace cantilever walls with Reinforced Steepened Slopes (RSS) where ROW permits.

3. Single Lane Roundabouts $0.5 M 11% Construct both roundabouts on Louisiana Avenue as single lane roundabouts. The Louisiana Avenue roadway connecting the roundabouts should be designed for a single lane in each direction with the option to expand in the future when necessary.

4. Remove Median on Louisiana Avenue $0.1 M 6% Eliminate the raised median on Louisiana Avenue in order to give the roadway more of an “urban character” and to potentially provide some measure of traffic calming and less impervious surface.


5a. Tight Urban Diamond Interchange $1.5 M 7% Using the same plan and profile as the baseline idea for TH 7 and Louisiana Avenue, construct a tight urban diamond interchange (TUDI).

5b. Single Point Roundabout Interchange $0.3 M 21% Using the same plan and profile as the baseline idea, construct a Single Point Roundabout Interchange (SPRI). This would be done instead of button hook ramps to roundabouts to accommodate the ramp traffic to/from TH 7 and Louisiana Avenue. See example to the right.

Implementation Strategies

Because of competing recommendations, three different implementation strategies or scenarios are available. Recommendations 1a, 1b and 1c all offer different ways to construct embankments. Recommendations 5a and 5b are both differing types of interchanges than the baseline concept.

Scenario A includes Recommendations 1, 2, 3, and 4. These 4 recommendations all improve the baseline concept. Collectively they have a net cost savings of $4.1 million and an overall performance improvement of +8%.

Scenario B recommends a Tight Urban Diamond Interchange (5a). Combined with Recommendations 1, 2 and 4 it has a net cost savings of $5.1 million and an overall performance improvement of +7%.

Scenario C recommends a Single Point Roundabout Interchange (5b). This recommendation combined with Recommendations 1, 2 and 4 has a net cost savings of $3.9 million and an overall performance improvement of +11%.


Summary of Recommendations TH 7 at Louisiana Ave. Interchange

# Description

Scenario A Scenario B Scenario C

Cost Savings

Cost Savings

Cost Savings

1a Ground Improvements $2.4 M $2.4 M $2.4 M 1b Lightweight Fill $2.2 M $2.2 M $2.2 M 1c Pile Supported Fill $2.5 M $2.5 M $2.5 M 2 Reinforced Slopes $1.1 M $1.1 M $1.1 M 3 Single Lane Roundabouts $0.5 M 4 Remove Median on Louisiana Avenue $0.1 M $0.1 M $0.1 M 5a Tight Urban Diamond Interchange $1.5 M 5b Single Point Roundabout Interchange $0.3 M

Total $4.1 M $5.1 M $3.9 M

Implementation of Recommendations

To facilitate implementation, a Value Engineering Recommendation Approval Form is included in the Appendix of this report. If the Project Manager elects to reject or modify a recommendation, please include a brief explanation of why.

VE Team Members

Don Owings HDR Team Leader/Facilitation Blane Long HDR Co-Facilitation/Roadway Minnie Milkert Mn/DOT State Value Engineer Nick Haltvick Mn/DOT Bridge Engineer Hossana Teklyes Mn/DOT Assistant Foundation Engineer Mike Rardin City of Saint Louis Park Public Works Director Brian Kelly Mn/DOT Water Resources Jim Olson City of Saint Louis Park Project Manager Diane Colton Mn/DOT Traffic Ken Johnson Mn/DOT Traffic April Crockett Mn/DOT West Area Engineer Derrick Dasenbrock Mn/DOT Geometrics Engineer


The Project Manager for this project is Jim Olsen, City of Saint Louis Park.

The VE Team wishes to express its appreciation to the project design managers for the excellent support they provided during the study. Hopefully, the recommendations and other ideas provided will assist in the management decisions necessary to move the project forward through the project delivery process.

Don Owings, PE, CVS VE Team Leader


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TH 7 at Louisiana Avenue Interchange Project Description – 1.1 Value Engineering Study Report Date: August 10-13, 2010

PPrroojjeecctt DDeessccrriippttiioonn This Value Engineering (VE) Report summarizes the events of the VE Study conducted by City of Saint Louis Park, Minnesota and facilitated by HDR Engineering, Inc. The subject of the study was the TH 7 at Louisiana Avenue Interchange project. The VE Study was conducted August 10-13, 2010.

Proposed Project

The proposed project is to remove the existing at-grade signalized intersection of TH 7 and Louisiana Avenue and replace it with a grade-separated interchange. The project is located in the City of St. Louis Park, Minnesota, which is an urbanized first-tier suburb in the western Twin Cities metropolitan area.

The intersection of TH 7 and Louisiana Avenue has consistently ranked high on Mn/DOT's Top 200 Highest Crash-Cost Intersections on Trunk Highways. Interim improvements to signal timing in 2005 appear to have helped reduce rear end crashes moving the ranking from 23rd from the top in 2005 to 144th in 2007.

As traffic volumes increase and intersection operations become more congested, the instances of rear end crashes is expected to increase. Further, drivers who become frustrated with waiting for long periods at a traffic signal, may engage in more risky behaviors such as running yellow or red lights and speeding through the intersection.

Baseline concept for the proposed project


Existing Conditions

TH 7 is a principal arterial that connects a number of employment centers and commercial nodes to residential developments within the cities of St. Louis Park, Minnetonka, Hopkins, and Minneapolis. It serves an important role in connecting the western Twin Cities metropolitan area to jobs in downtown Minneapolis and along the corridor. In the project area, TH 7 is a four lane divided highway. Louisiana Avenue is currently a four-lane, undivided roadway that intersects TH 7. The intersection is controlled by a traffic signal system.

The project area contains a mix of land uses, including low and high density residential, commercial, corporate/office, manufacturing, and open space. Just east of the TH 7/Louisiana Avenue intersection, a new grade separated interchange is being constructed at the intersection of TH 7 and Wooddale Avenue. A future Southwest Light Rail Transit (LRT) station is planned along the east side of Louisiana Avenue, which will be located just south of the project area. St. Louis Park has several redevelopment plans along the transit corridor and surrounding the future station.

Project Purpose and Need

The purpose of the proposed TH 7 and Louisiana Avenue Interchange project is to address deteriorating safety and operational conditions. These deficient conditions are resulting in numerous crashes and causing high levels of congestion. The project is also intended to improve pedestrian and bicycle movements across TH 7 that are anticipated to increase with the construction and operation of a future LRT Station along Louisiana Avenue. Lastly, the transportation improvements will help foster economic development in the area.

The need for the project is driven by:

Improve vehicle safety Maintain mobility/future traffic capacity Improve pedestrian/bicycle movements Foster economic development.


Scope of the Value Engineering Study

The mission of the VE Team was to verify or improve upon various concepts for the TH 7 at Louisiana Avenue Interchange project. The VE Team applied the principles and practices of the VE Job Plan. The primary objectives for this study include:

Conduct a thorough review and analysis of the key project issues and conceptual design using a multidiscipline, cross-functional team

The focus of the Value Engineering Study is to assist in the identification of o Alternatives that will improve the mobility and reduce the conflicts of vehicular and

non-vehicular traffic

o Alternatives that will minimize impacts to existing developments and enhance opportunities for future development/redevelopment

o An environmentally sensitive transportation system improvement that solves the identified purpose and needs

Constraints and Controlling Decisions

The VE Team identified the following constraints and controlling decisions during the Investigation Phase of the study.

Must accommodate bicycles and pedestrians during construction and in the proposed design

Avoid impacts to the Louisiana Oaks apartment complex Avoid impacts to Sam’s Club Avoid impacts to the railroad overcrossing over TH 7 at the east end of project Desire to close right in-right out access to TH 7 at the east end of the project Project letting is scheduled for November 2011 with a March 2012 funding obligation

date – there is a potential for a 1-year extension with prior approval by Met Council Minimize right-of-way impacts and acquisition Minimize excavation (high potential of contaminated soils) Environmental Assessment (EA) process is just starting – the draft document is

scheduled to be out by October 2010 Any impacts to the flood plain will need to be mitigated – no net increase in 100-year

flood elevation Strong desire not to impact the pump station and medical offices along Lake Street Strong desire not to impact medical offices along Walker Street Avoid any impacts to 4f properties Strong desire to minimize impacts in the SW quadrant of the proposed interchange.


Information Provided to the VE Team

The following project documents were provided to the VE Team for their use during the study:

Reports/Drawings/Maps Date LWD cost estimate July 2010

Various aerial photos

Phase I Environmental Site Assessment August 2009

Preliminary Drainage Report July 2010

Purpose and Need Statement – Draft August 2010

Profiles and typical sections

Technical Memorandum - Alternatives Screening April 2009

Technical Memorandum - Draft TH 7/Louisiana Avenue Interchange - Option 4 Review June 2009

Options 1-10 preliminary design

Soil boring index map

Hydric soils map February 2009

Soils map February 2009

Other soil maps of specific areas 1985-2007

Utility maps

TH 7 at Louisiana Avenue Interchange Project Analysis – 2.1 Value Engineering Study Report Date: August 10-13, 2010

PPrroojjeecctt AAnnaallyyssiiss Project Issues The first day of the study included a project presentation (overview) by the design team and a site visit. The following summarizes key project issues, site visit observations, and project drivers identified during these sessions.

The proposed profile on TH 7 west of Louisiana Avenue will create a roller coaster effect Several utilities at the intersection Existing field conditions (roadway locations) differ from those shown on geotechnical data

from initial construction (30 years ago) – additional investigation will be needed Very tight conditions for staging construction and traffic Louisiana Avenue traffic (ADT) can be handled by a single lane in the proposed design Bus route along Walker Street, et al The current signal cycle length is too long.

Cost Model

The VE Team Leader prepared a cost model from the cost estimate of the baseline, which was provided by the Project Team. The models are organized to identify major construction elements or trade categories, the designer's estimated costs, and the percent of total project cost for significant cost items. The cost models clearly showed the cost drivers for the project and were used to guide the VE Team during the study. The following conclusions were noted by the VE Team regarding the project costs:

Roadway Items including bituminous account for 33% of this project Contaminated soil and muck removal on TH 7 is 23% of the estimate A new bridge over Louisiana Avenue is 13% of the estimate. No cost estimate for right of way acquisition. It was not clear what was included with the items Contaminated Soil Removal & Backfill or

Muck Excavation & Backfill. The team felt a large amount of sheet piling would be needed during these operations but did not know if the cost was in the estimate.

It also was unknown where the Contaminated Soil would need to be disposed at. This could be a very large dollar item.


Cost Model – Baseline Concept

Items $$$ % of Total Cumulative %

Roadway $6,526,500 33% 33%

Engineering Total 20% of Construction $3,314,202 17% 49%

Contaminated Soil Removal & Backfill $3,083,548 16% 65%

Bridge $2,577,135 13% 78%

Retaining Wall $2,455,613 12% 90%

Muck Excavation & Backfill $1,398,917 7% 97%

Median Barrier $331,300 2% 99%

Dewatering $198,000 1% 100%

Total $19,885,215 100%


Functional Analysis

Functional analysis results in a unique view of the study project. It transforms project elements into functions, which moves the VE Team mentally away from the original design and takes it toward a functional concept of the project. Functions are defined in verb-noun statements to reduce the needs of the project to their most elemental level. Identifying the functions of the major design elements of the project allows a broader consideration of alternative ways to accomplish the functions.

Items Verb Noun

Bridge Span Roadway

HMA & Surfacing Support

Add Widen

Load Lanes

Roadway Earthwork Move Earth Retaining Walls Retain Earth

Roundabout Maintain Control

Access Traffic

Curb & Sidewalk Create Pedestrian Path

Traffic Control Protect Convey Maintain

User/Worker Information

Traffic Temporary Signal Systems Control Traffic


FAST Diagram The FAST diagram arranges the functions in logical order so that when read from left to right; the functions answer the question “How?” If the diagram is read from right to left, the functions answer the question “Why?” Functions connected with a vertical line are those that happen at the same time as, or are caused by, the function at the top of the column.

The FAST Diagram for this project shows Reduce Conflicts, Improve Mobility, and Create Access as the basic functions of this project. Key secondary functions include Construct Interchange and Stage Construction. This provided the VE Team with an understanding of the project design rationale and which functions offer the best opportunity for cost or performance improvement.


Performance Attributes

Performance measures are an integral part of the VE Process. Project performance must be properly defined and agreed upon by the Project Team, VE Team and stakeholders at the beginning of the VE Study. The performance attributes and requirements developed are then used throughout the study to identify, evaluate, and document alternatives.

The VE Team, along with the Project Team, identified and defined the performance attributes for this project and then defined the baseline concept against these attributes. Performance attributes represent those aspects of a project’s scope and schedule that may possess a range of potential values.

Baseline Concept

The baseline concept provides access to Highway 7 via button hook ramps located in the northeast and southwest quadrants. All entering and exiting traffic is directed through roundabouts at intersections with local streets that then connect to Louisiana Avenue. In this concept, TH 7 goes over Louisiana Avenue.


The following are the key project performance attributes and their definition that were used in this VE Study.

Evaluation of Baseline Project

Standard Performance

Attribute Description of Attribute Baseline Design Rating Rational Rating

Mainline Operations

An assessment of traffic operations and safety on TH 7. Operational considerations include level of service relative to the 20-year traffic projections as well as geometric considerations such as design speed, sight distance, lane widths and shoulder widths.

50 mph design speed 2 - 12' lanes in each direction 4' inside & 10' outside shoulders Walls limit future expansion Acceleration lanes create 3rd

lane on structure right-in, right out closed to Lake

and south service road

5

Local Operations

An assessment of traffic operations and safety on the local roadway infrastructure. Operational considerations include level of service relative to the 20-year traffic projections; geometric considerations such as design speed, sight distance, lane widths; bicycle and pedestrian operations and access.

Louisiana Avenue 12' lanes, 2' shoulder and 2' curb

and gutter, 6' median 6' boulevard between curb and

path 6' sidewalk eastside, 10' shared

use path on west Lake - 10' sidewalk on south Walker - 6' sidewalk on north 4 Roundabouts

o TH 7 eastbound on and off ramps to Lake

o Lake and Louisiana o Walker and Louisiana o TH 7 westbound on and off

ramps to Walker Connection from Walker to

Republic is closed

5

Maintainability

An assessment of the long-term maintainability of the transportation facility(s). Maintenance considerations include the overall durability, longevity, and maintainability of pavements, structures and systems; ease of maintenance; accessibility and safety considerations for maintenance personnel.

Bituminous pavement over crushed surfacing

Concrete pre-stressed girder bridge

Some cast-in-place retaining walls

Open stormwater ponds

5


Evaluation of Baseline Project

Standard Performance

Attribute Description of Attribute Baseline Design Rating Rational Rating

Construction Impacts

An assessment of the temporary impacts to the public during construction related to traffic disruptions, detours and delays; impacts to businesses and residents relative to access, visual, noise, vibration, dust and construction traffic; and environmental impacts.

Access will need to be maintained to local businesses

Louisiana Avenue and TH 7 will need one-lane each direction at all times

Noise ordinance 7 am to 10 pm on weekdays and 9 am to 7 pm on weekends

Pedestrian access will be maintained through Louisiana Avenue

Dewatering is possible The Reilly Super Fund site is

adjacent to project – hazardous material relocation may be required with excavated material

Large quantity of embankment is necessary for the raising of TH 7

5

Environmental Impacts

An assessment of the permanent impacts to the environment including ecological (i.e., flora, fauna, air quality, water quality, visual, noise); socioeconomic impacts (i.e., environmental justice, business, residents); impacts to cultural, recreational and historic resources.

Environmental Assessment is in the early phases of development

Noise walls anticipated but not defined in the NW and SW quadrants

Flood plain impacts Water quality impacts Right-of-way will be needed

5

Project Schedule

An assessment of the total project delivery from the time as measured from the time of the VE Study to completion of construction.

November 2011 Letting (dependent on funding)

2 season construction schedule is anticipated

5

Risks

An assessment of the identified risks of the project.

Reilly Super Fund Site adjacent to project

Utility relocations NPDES permitting if project

letting slides Subsurface materials Loss of federal funds if project is

not authorized by March 2012 All funds are not currently

available

5


Performance Attribute Matrix

The performance attribute matrix was used to determine the relative importance of the performance attributes for the project. The project owner, design team, and stakeholders evaluated the relative importance of the performance attributes that would be used to evaluate the creative ideas.

These attributes were compared in pairs, asking the question: “Which one is more important to the project?” The letter code (e.g., “A”) was entered into the matrix for each pair. After all pairs were discussed, they were tallied (after normalizing the scores by adding a point to each attribute), and the percentages calculated. The Performance Attribute Matrix is shown below.

Value Matrix

As the VE Team develops alternatives, the performance of each is rated against the original design concept. Changes in performance are always based upon the overall impact to the total project. Once performance and cost data have been developed by the VE Team, the net change in value of the VE alternatives can be compared to the original design concept. The resulting “Value Matrix” provides a summary of these changes and allows a way for the Project Team to assess the potential impact of the VE recommendations on total project value.

While the ratings for the individual VE recommendations are included with the documentation of each recommendation, this section of the report includes the documentation of the performance ratings for the concepts that were developed during the VE Study.

In order to compare and contrast the potential for value improvement, individual recommendations are compared to the baseline project for the all attributes. For this exercise the baseline is given a score of 5.

A A/B A A A/E F A 5.0 18%

B B B B/E F B 5.0 18%

C C C/E F C 3.5 13%

D E F G 1.0 4%

E F E 4.5 16%

F F 7.0 25%

G 2.0 7%

28.0 100%

Risks

Mainline Operations

Local Operations

Maintainability



Project Schedule

Which attribute is more important to the project? TOTAL %


1 2 3 4 5 6 7 8 9 10Baseline 5 89

1a 5 891b 5 891c 5 892 5 893 5 894 5 895a 7 1255b 7 125

Baseline 5 891a 5 891b 5 891c 5 892 5 893 8 1434 6 1075a 4 715b 7 125

Baseline 5 631a 5 631b 5 631c 5 632 5 633 5 634 6 755a 5 635b 5 63

Baseline 5 181a 7 251b 6 211c 7 252 6 213 5 184 5 185a 6 215b 6 21

Baseline 5 801a 6 961b 5 801c 5 802 7 1133 5 804 5 805a 6 965b 7 113

Mainline Operations 17.9

Local Operations 17.9

Maintainablity 12.5

VALUE MATRIX

Attribute ConceptPerformance Rating Total

PerformanceAttributeWeight

TH 7 at Louisiana Ave Interchange

Construction Impacts 3.6

Environmental Impacts 16.1


The matrix is essential for understanding the relationship of cost, performance, and value of the project baseline and VE proposals. Comparing the performance and cost suggests which recommendations are potentially as good as or better than, the project baseline concept in terms of overall value. Comparison at the value index level suggests which recommendations have the best functionality per unit cost, or provides the project with the “best value.”

Baseline 5 1251a 5 1251b 5 1251c 5 1252 5 1253 5 1254 5 1255a 5 1255b 5 125

Baseline 5 361a 8 571b 3 211c 8 572 5 363 5 364 5 365a 5 365b 5 36

Risks 7.1

Project Schedule 25.0

1a 27%

1b 13%

1c 25%

2 15%

3 14%

4 7%

5a 18%

5b 24%

Scenario 1 44%

Scenario 2 55%

Scenario 3 45%24% 44.01

9% 35.83

2% 37.48

25%

31%

43.63

47.11

Tight Urban Diamond Interchange 7%

Single Point Roundabout Interchange 607

11% $12.6554

541

#1a, #2, #4, #5b

#1a, #2, #3, #4

#1a, #2, #4, #5a

$12.4

$11.4

$15.0

$16.2

% Value Improvement

Value Index (P/C)

30.30

38.63

% Change CostOVERALL PERFORMANCE

% ChangePerformance

Performance (P)

500

545

Baseline

Ground Improvements

34.22$14.3

15%

13%

$14.0

-2%

6%

Cost (C)

9%

$16.5

$14.1

7% 34.79

1%

529

554

536

37.76

6% $16.4

$16.0 3%

7%

34.6011%

15%

32.34

$15.4

489

Reinforced Slopes

Single Lane Roundabouts

No Median on Louisiana 530

538

21%

537

8%

7%

Lightweight Fill

Pile Supported Embankment


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TH 7 at Louisiana Avenue Interchange Idea Evaluation – 3.1 Value Engineering Study Report Date: August 10-13, 2010

IIddeeaa EEvvaalluuaattiioonn Introduction The ideas generated by the VE Team are carefully evaluated, and project-specific attributes are applied to each idea to assure an objective evaluation.

Evaluation Process The VE Team, as a group, generated and evaluated ideas on how to perform the various functions. The idea list was grouped by function or major project element. These ideas were discussed fully and the advantages and disadvantages of each were listed.

The evaluation process considered seven attributes that considered key aspects of project performance:

Mainline operations (MO) Local operations (LO) Maintainability (M) Construction impacts (C) Environmental impacts (E) Project schedule (S) Risk (R)

The VE Team compared each of the ideas with the baseline concept for each of the performance attributes to determine whether it was better than (), equal to (), or worse than () the original concept.

Deposition of Ideas The VE Team reached a consensus on the overall rating of the idea (1 through 5). High-ranked ideas (those ranked three or higher) were developed further; low-ranked ones (those less than three) were dropped from further consideration. The ranking values are shown below:

5 = Significant Value Improvement 4 = Good Value Improvement 3 = Equivalent to the Baseline 2 = Minor Value Degradation 1 = Significant Value Degradation 0 = Fatal Flaw

Idea Evaluation Form All of the ideas that were generated during the creative phase using brainstorming techniques were recorded on the Idea Evaluation Form on the following pages.

Based on the available information along with the constraints and controlling decisions that were given to the VE Team at the time of the study, many ideas were not advanced to recommendations or design considerations. These ideas were either fatally flawed or the baseline concept or other ideas proved to be a higher value improvement after discussion and the initial evaluation was made. Please refer to the Idea Evaluation Forms for additional information on those ideas.

Rating Scale: 5 = Significant Value Improvement 2 = Minor Value Degradation 4 = Good Value Improvement 1 = Significant Value Degradation or Doesn’t Meet Project Purpose & Need 3 = Equivalent to Baseline 0 = Fatal Flaw Performance Attributes: Significant Improvement Significant Degradation


IDEA EVALUATION

# Ideas Performance Attributes Advantages Disadvantages Rating MO LO M C E S R

Function: Move Earth

1

Use ground improvement technologies (TH 7) rather than excavating muck Deep soil mixing in lieu of

excavation Stone columns Vibro-compaction Densification

Reduces disposal of contaminated soils

May have preservation effect (containing contamination movement)

Potential to reduce construction schedule

Reduces borrow (no backfill of muck excavation) – reduced truck traffic in corridor

Potential to eliminate surcharge period

Potential reduction in noise levels – bridge foundations on spread footing w/ ground improvements in lieu of piles

Eliminate or significantly reduce settlement

May be higher cost than baseline

May require specialty contractor

Performance specifications

Risk of soil wave – outside embankment area

4

Comments: Material on east side of Louisiana Avenue is not anticipated to settle, and excavation of muck is not expected.



IDEA EVALUATION


2 Land bridge – where applicable to avoid muck/peat (potential contaminated material) excavation

Bridges potential settlement area

Reduced excavation – resulting in reduced truck traffic

Potential for reducing retaining walls (cost)

Eliminates borrow in areas Eliminates risk of

contaminated material disposal

May increase length of noise impacts – pile supported columns

Potential increase in cost Additional structure to

maintain Potential increase in

construction time Potential increase in

design effort/time

2

Comments: Land bridge is a beam supported structure 1 to 2 feet off of the ground surface. Pile supported columns with bent caps. May not be beneficial.

3 Lightweight fill – Geofoam blocks over concrete slab

Reduced settlement Reduced truck traffic –

reduces excavation of muck May reduce schedule Reduces borrow material –

reduced construction traffic Easy to construct

Increased cost? Staging could be difficult

– interlocking blocks & ½ time construction

May complicate design Potential risk associated

with foam/petroleum mix (contaminated soils)

Would preclude utilities from entering fill area

4

Comments:



IDEA EVALUATION


4 Viaduct – use instead of embankment/walls on west side

Potentially eliminates excavation and fill on west side of Louisiana

Reduces retaining walls Less risk with bridge

construction vs. excavation (overruns ground water, etc.)

Increased cost over embankment

Increased maintenance Potentially increase

construction schedule Traffic staging More noise impacts Adds to complexity of

construction with ramps tying into bridge

2

Comments: Assumes baseline will design to minimize future settlement not eliminate all together.

5 Use deep soil mixing in lieu of excavation

Comments: Included in Idea #1.

6 MSE Walls – base assumed to be cast-in-place

Potentially cheaper than CIP wall

Can easily accommodate settlement

Smaller footing required (leveling pad)

Potentially easier to construct

Potential reduced cost

Relatively small area – may not get economy of scale

Mn/DOT does not build a lot of these wall types – potential design and construction issues

3



IDEA EVALUATION


Comments: Move to design consideration.

7 Pile supported embankment

Eliminate excavation – reduced construction traffic

Reduces long term maintenance – no long term settlement

Temporary sheeting not needed

Less risk with bridge construction vs. excavation (overruns ground water, etc.)

Potential increased cost - need to evaluate

Increased noise – pile driving – may be offset by sheeting elimination 5

Comments:

8 Raise TH 7 higher and eliminate excavation/lowering of Louisiana

Reduces staging complexity – lower of Louisiana (6 to 7 feet) and raising of TH 7 (partial) will be very complicated

Reduces excavation Less risk vs. excavation

(overruns ground water, contaminated soils, etc.)

May reduce construction schedule

Increased embankment May require lengthening

of vertical curve – tie-ins to existing TH 7

Will increase grade on loop ramps (on ramps)

Increases fill height in front of apartment complex – negative impact

4



IDEA EVALUATION


Comments:

9 Reinforced slopes

Can accommodate settlement – without needing adjustments

Reduced cost May increase footprint some

(70 degree max slope) May improve aesthetics –

grass covered slope Reduced construction time

May have difficulty with slope cover growing (grass)

Increase maintenance – landscape maintenance 4

Comments: Will need to investigate the right of way needs.

10 Balance earthwork – lower Louisiana Avenue (assumes that excavation can be used as fill)

Alignment along TH 7 may be lower

Significant increase in excavation required

Will impact access to businesses

Increases staging complexity

Lengthen project limits along Louisiana

Stock pile site required Project area would need

to significantly increase to obtain enough material

0



IDEA EVALUATION


Comments: Fatally flawed – see disadvantages.

11 Lower hill between Texas and Louisiana to acquire material for embankment

Improved vertical alignment along TH 7

Improves sight distance over existing along TH 7 approaching Texas from the east

Provides potential borrow

May need to construct cut retaining walls

Potential increase in design effort/time

Increase in construction impacts to TH 7 outside of the project limits

3

Comments: Moved to design consideration.

Span Roadway – Baseline Prestressed concrete girder, vertical abutments - TH 7 over Louisiana

12 Steel Girder Bridge Similar construction to concrete Maintainability 3




IDEA EVALUATION


13 Accelerated Bridge Construction (ABC) (components)

Potential construction schedule savings

May be an avenue to additional funding

Requires a lay down area for the pre-cast components

Relatively new technology in the area

Currently a lot of cracking is occurring on the few attempts in this area with bridge decks

4

Comments: After evaluation this idea was moved to a design consideration.

14 Twin bridges in lieu of single bridge May simplify staging Added light under bridge Eliminates closure pour

Bridge barrier is added last

Increased footprint 3


15 Slab span bridge

Depth of deck is reduced Reduces borrow/retaining

wall height Aesthetically nicer looking

bridge

Center pier needed to span over Louisiana

More intricate falsework 2

Comments: Need for impact attenuators or other protection scores this low.



IDEA EVALUATION


16 Have Louisiana Avenue span TH 7 Steeper profile on Louisiana 0

Comments: Fatally flaw based on grades needed for approaches to bridge.

17 Use three-span structure – no vertical abutments

Less embankment Increases light under bridge More comfortable for

pedestrians Easier to widen in the future

than vertical abutment Reduces muck excavation

Increases cost Increased construction

schedule 2 more bridge foundations

to construct 4

Comments: After evaluation this idea validated the baseline.

18 Tied Arch Bridge 1

Comments: Beyond the funding of the project.

19 Signature Structure – welcome to Saint Louis Park (form vs. function) 3




IDEA EVALUATION


20 Lengthen Bridge – additional spans Reduced excavation of muck

Comments: Added to Ideas #4 & #17.

Construct Ramps

21

Evaluate Tight Urban Diamond Interchange – use the same horizontal and vertical alignments as baseline

Smaller footprint Driver expectation is better

than with slip ramps to roundabouts

Bike and ped friendly Less impacts to current

access to business to the north

Ramp design is better

Possible impacts to pump station and medical building in SE quadrant

Increased conflicts over roundabouts

Business impacts to Sam’s club (truck access)

Bikes and peds may have more conflicts

Reduces the size of the city land

Increased bridge May be opposed by

apartments – proximity

4

Comments:



IDEA EVALUATION


22

Single point diamond interchange with one roundabout – use the same horizontal and vertical alignments as baseline

Reduce overall project footprint (no need for two extra roundabouts)

Increase driver expectation Less impacts to current

access to business to the north

Ramp design is better

Requires a larger structure because of increase need sight distance

Possible impacts to pump station and medical office in SE quadrant

Reduces the size of the city land

4

Comments: Single lane roundabout will work but requires shift to the south for TH 7.

23 Cul-de-sac the frontage road in the SW quadrant

Removes one access point to roundabout which improves the operation

Improved angle at which ramps approach

Neighbors may not approve

4

Comments:

24 Diverging Diamond Interchange 0

Comments: Fatally Flawed because it has no advantages over the typical diamond which was rejected in the evaluation matrix (little known).

25 Super tight diamond with shift TH 7 to the south – space from apartment



IDEA EVALUATION


Comments: Added to Idea #21

26 Offset single point (TH 36/Rice Street)

Impacts to pump station, medical office, and parking lot

Access from lake street to Louisiana Avenue is gone

1

Comments: Will work geometrically if combined with viaduct idea. Scored low because of no advantages over base.

27

Construct roundabouts first – shift TH 7 to roundabouts – provide slip ramps in SE and NW quads for TH 7 traffic – use ABC

Comments: Combined with Idea #45.

28 Construct TH 7 from the air by suspending TH 7 from balloons 1

Comments: Unproven technology

29 Lengthen RR bridge to accommodate ramps Working with railroad 1

Comments: Not enough time to work with railroad to design new bridge.



IDEA EVALUATION


30

Eliminate all left turns by creating a single large traffic circle - TH 7 and Louisiana Avenue would be removed in the middle

All at-grade construction Eliminates muck excavation Reduces cost

Buy-in by apartment complex

Driver expectancy Design speed on TH 7

would be reduced Risk of Mn/DOT approval

1

Comments: Mn/DOT approval.

31 Use ovalabouts in NW and SE quads instead of 2 roundabouts 1

Comments: operational doesn’t work.

32 Use right in – right out at W. Lake Street and Louisiana Avenue Truck access to Sam’s

Club 1

Comments: Operationally doesn’t work.

Reconstruct City Streets

33 Accommodate transit 3

Comments: Include with design considerations.



IDEA EVALUATION


34 Grade separate – eliminate access at Louisiana 1

Comments: Doesn’t meet the purpose and need of the project.

35 Rain gardens in center of roundabouts

Comments: Include as a design consideration.

36 Single lane roundabouts with one lane between them

Reduces conflicts Smaller footprint Easier to navigate from the

drivers perspective Ability to expand in future

when necessary Reduces impervious surface

4

Comments: Construct to full size but use as a single lane until traffic warrants.

37 Narrow Louisiana – use three lane section with two way left turn lane (TWLTL)

Reduces ability to expand

in the future 1

Comments: No need for a TWLTL on Louisiana Ave (only two access and they are right in-right out.



IDEA EVALUATION


38 Narrow Louisiana – remove raised median and replace with double yellow stripe

Reduces impervious surface Improve snow removal Reduces bridge length

Public perception 4

Comments:

39 Louisiana – parking on outside in each direction (one lane each direction)

1

Comments: No need for parking in this stretch of Louisiana Avenue.

40 Louisiana – wider boulevard section with rain gardens Aesthetics Maintenance 3


41 Remove boulevard (strip between curb and sidewalk) Reduces footprint Loss of area for snow

removal Moves pedestrians closer

to traffic

2

Comments:

42 Use pervious pavement Infiltration is good Reduction in stormwater

system

More costly Maintenance Breaks down quicker

2



IDEA EVALUATION


Comments: Unknown if we would get any credit for this type of pavement – possibility to use on trails if not roadway.

43 Use concrete on roundabouts Higher life cycle Less maintenance

Pavement markings are more difficult to see

Staging becomes more problematic

3


44 Concrete roundabouts – use pigmented concrete i.e., black

Ability to see pavement markings

Risk of coloration differences within roundabouts

3

Comments: Move to design considerations.



IDEA EVALUATION


Stage Construction

S1

1. Build roundabouts first w/temporary slip ramps in SE & NW quads

2. Build ½ TH 7 at a time 3. Build twin (or half) structures to

facilitate staging 4. Move the Louisiana Avenue

intersection with TH 7 to Lake Street (east) (current right in-right out location) during construction

Comments:

S2 Shift TH 7 traffic south (temporary road) and construct TH 7 all at once

Reduces staging complexity Can build as a single

structure Potential reduction in cost Reduced construction

schedule

Reduced spacing between signal Louisiana and Lake

Comments:



IDEA EVALUATION


S3 Shift TH 7 south using Lake Street for and TH 7 all at once

Reduces staging complexity Can build as a single

structure Potential reduction in cost Reduced construction

schedule

Lake may not be able to handle the added traffic

May introduce additional conflicts – thru traffic on frontage road

Utilizes existing infrastructure

Comments:

S4 Shift Louisiana Avenue to the east during the lowering of the profile

Comments:

TH 7 at Louisiana Avenue Interchange Recommendations – 4.1 Value Engineering Study Report Date: August 10-13, 2010

RReeccoommmmeennddaattiioonnss

Introduction

The results of this study are presented as individual recommendations to the original concept. The VE recommendation documents in this section are presented as written by the team during the VE Study. While they have been edited from the draft VE Report to correct errors or better clarify the recommendation, they represent the VE Team’s findings during the study.

Summary of VE Recommendations

Each recommendation consists of a summary of the original concept, a description of the suggested change, a listing of its advantages and disadvantages, a cost comparison, change in performance*, and a brief narrative comparing the original design with the recommendation. Sketches, calculations, and performance measure ratings are also presented. The cost comparisons reflect a comparable level of detail as in the original estimate.

* Please refer to the Project Analysis section of this report for an explanation of how the performance measures are calculated.

The VE Team generated 44 different ideas for this project. These concepts were compared against the baseline that was developed by the project team. The concepts that performed the best were further developed by the VE Team.

From these ideas the VE Team developed 8 recommendations resulting in a net cost savings of $ 3.9 M to $5.1 M and an overall performance improvement of +7 to +11%.


# Description Cost Savings Performance Improvement

1a Ground Improvements $2.4 M 9%

1b Lightweight Fill $2.2 M -2%

1c Pile Supported Fill $2.5 M 6%

2 Reinforced Slopes $1.1 M 7%

3 Single Lane Roundabouts $0.5 M 11%

4 Remove Median on Louisiana Avenue $0.1 M 6%

5a Tight Urban Diamond Interchange $1.5 M 7%

5b Single Point Roundabout Interchange $0.3 M 21% Total $3.9 M to $5.1M +7% to +11%


Implementation Strategies

Because of competing recommendations, three different implementation strategies or scenarios are available. Recommendations 1a, 1b and 1c all offer different ways to construct embankments. Recommendations 5a and 5b are both differing types of interchanges than the baseline concept.

Scenario A includes Recommendations 1, 2, 3, and 4. These 4 recommendations all improve the baseline concept. Collectively they have a net cost savings of $4.1 million and an overall performance improvement of +8%.

Scenario B recommends a Tight Urban Diamond Interchange (5a). Combined with Recommendations 1, 2 and 4 it has a net cost savings of $5.1 million and an overall performance improvement of +7%.

Scenario C recommends a Single Point Roundabout Interchange (5b). This recommendation combined with Recommendations 1, 2 and 4 has a net cost savings of $3.9 million and an overall performance improvement of +11%.


# Description Scenario A Scenario B Scenario C

Cost Savings

Cost Savings

Cost Savings

1a Ground Improvements $2.4 M $2.4 M $2.4 M

1b Lightweight Fill $2.2 M $2.2 M $2.2 M

1c Pile Supported Fill $2.5 M $2.5 M $2.5 M

2 Reinforced Slopes $1.1 M $1.1 M $1.1 M

3 Single Lane Roundabouts $0.5 M

4 Remove Median on Louisiana Avenue $0.1 M $0.1 M $0.1 M

5a Tight Urban Diamond Interchange $1.5 M

5b Single Point Roundabout Interchange $0.3 M

Total $4.1 M $5.1 M $3.9 M


VE Recommendation Approval

The Project Manager shall review and evaluate the VE Team’s recommendation(s) that are included in the Final Report. The Project Manager shall complete the VE Recommendation Approval form that is included in this report.

For each recommendation that is not approved or is modified by the Project Manager, justification needs to be provided. This justification shall include a summary statement containing the Project Manager’s decision not to use the recommendation in the project.

The completed VE Recommendation Approval form including justification for any recommendations not approved or modified shall be sent to the State Value Engineer by October 1 of each year so the results can be included in the annual Value Engineering Report to the Federal Highway Administration (FHWA).

Design Considerations

The VE Team generated several ideas for consideration by the Project Team. These items represent ideas that are relatively general in nature, and are listed below. Please refer to the Idea Evaluation Forms for more detail.

Use MSE Walls Lower the hill (profile) on TH 7 between Texas Avenue and Louisiana Avenue to acquire

material for embankment With the current low prices for steel, consider a steel girder bridge Use two bridges instead of one Create a signature bridge Include transit in final design Consider the use of rain gardens in the roundabouts and boulevards Use concrete instead of bituminous for the driving surface of the roundabouts Use Accelerated Bridge Construction (ABC), see write up on following pages.

Construction Staging

The VE Team also looked at how this project might be staged during construction. The team felt it would be challenging to keep one lane of traffic open both directions on TH 7 at all times because of the major excavation needed for muck removal.

Louisiana Avenue also needs to be maintained with one lane open at all times too. But the profile of Louisiana is being lowered 6-7 feet again making traffic management during construction a challenge.


During the study the team came up with a few suggestions to how traffic might be staged during the construction of the baseline concept as offered to the VE Team:

Idea #S1

1. Construct roundabouts first w/temporary slip ramps in SE & NW quads 2. Move intersection of Louisiana Ave and TH 7 to the intersection of Lake St. and TH 7 3. Construct TH 7 one half at a time (Construct a twin (or half) structure to facilitate staging)

Idea #S2 - Shift TH 7 traffic to the south (temporary road) and construct TH 7 all at once

Idea #S3 - Shift TH 7 south using Lake Street and construct TH 7 all at once

Idea #S4 – Shift Louisiana Avenue to the east during the lowering of the profile

Highway 7 at Louisiana Avenue Interchange Recommendations – 4.5 Value Engineering Study Report Date: August 10-13, 2010

VE DESIGN CONSIDERATION Accelerated Bridge Construction

Function: Span Roadway IDEA NO(s).

13

Original Concept:

The baseline concept (button hook ramps with roundabouts) calls for a single-span bridge with precast concrete girders supporting a cast-in-place deck. The structure will bear on cast-in-place vertical abutments, which will be supported by driven H-piles.

Design Consideration:

This design consideration is to provide a design (contractor flexibility) that will accommodate ABC technology. In essence provide design details that will give contractors the option to use precast substructure (pile caps, bent caps, etc.), superstructure components (i.e., partial depth structural precast concrete panels), and retaining walls (MSE wall with precast panels) in the construction of the bridges for the project. Coordination of these elements in conjunction with each other could result in construction time savings.

Advantages: Disadvantages Potential construction schedule savings

o Superstructure could occur simultaneously with embankment fill

Maybe an avenue to additional funding from FHWA for using accelerated bridge concepts

For this project, there appears to sufficient area for lay down areas to construct precast components on-site

Relatively new technology in the area Some bridge decks are experiencing premature

deck cracking when using precast components If the road project is staged, two separate bridges

would most likely would be required due to lack of a cold-joint



Discussion/Justification:

It is important to minimize traffic disruption during the construction. There are several businesses and a hospital to the south of TH 7 which use this intersection as a primary access point. The VE Team has considered Accelerated Bridge Construction (ABC) to help achieve minimal impacts to the traveling public as well minimize the impacts to local businesses.

Using prefabricated (precast) concrete elements as listed below will reduce the field forming and curing time required. Because prefabrication of these elements could be accomplished in a controlled, offsite environment without jobsite limitations; constructability will be improved, quality increased, costs lowered and the schedule shortened. Construction schedule may be affected by this method. Cost differentials are not presented because schedule costs cannot be quantified with available data.

Some of the bridge components to be considered as a part of this recommendation include the following:

Footings: Precast footings could be placed immediately following either pile driving or ground improvements.

Vertical walls abutments: Precast walls could be placed directly on footings. Specialty Girders: Inverted T or full-depth deck beams could be used to eliminate temporary

falsework required for casting of the deck. Deck: Prestressed deck panels could be placed on top of in-place girders. This eliminates

the need to remove falsework after the deck has been casted. Full Superstructure: The entire superstructure could be constructed in the existing parking lot

in the southwest quadrant of the intersection. Upon completion of the substructure components, the entire superstructure could be moved into place and set up the substructure. This allows for the construction of the substructure and superstructure to occur simultaneously.

Connections between CIP and precast components would be done placing concrete in/through small pockets cast into the precast elements. On-site forming, rebar installation, concrete placement and curing, and form removal are eliminated from the critical construction path

In order to enhance the benefits of ABC, other portions of the project should also be accelerated. In the baseline concept, the retaining walls are assumed to be cast-in-place walls. The recommended concept would need to include a plan which accelerates the construction of the retaining wall and embankment fill to ensure that the walls are ready at the same time as necessary bridge components.

Assumptions:

A major assumption for the project is that TH 7 traffic will remain within the current7 right-of-way corridor during the construction. Due to this, the bridge could be constructed in stages. Half of the bridge could be constructed first to maintain traffic within the existing right of way. Once this half is constructed, TH 7 traffic could be moved to this new portion while the second half of the bridge is being constructed. As a result of building the bridge in two stages, a cold-joint would most likely occur in both the substructure and superstructure components.

It is assumed that there will be no traffic on Louisiana Avenue at the bridge. The intersection of TH 7 and Louisiana Avenue will be temporarily relocated.



Sketches/Photos:

Precast components used for abutment construction.

Precast deck component used as falsework.

Moving entire superstructure into place.


VE RECOMMENDATION NO. 1a Ground Improvements

Function: Move Earth IDEA NO(s).

1

Original Concept:

Remove contaminated soil and muck and replace with borrow. It is assumed to require temporary sheeting and shoring to maintain a stable excavation; depths are expected to be up to 35 feet for removal in west bridge area. Another assumption is that the mineral soils and organic materials that are encountered will be contaminated with coal tar, or other creosote-type products and by-products.

Recommended Concept:

Use ground improvement technologies rather than excavating muck.

Deep soil mixing in lieu of excavation Stone columns Vibro-compaction Densification

Advantages: Disadvantages Reduces disposal of contaminated soils May have preservation effect (containing

contamination movement) Potential to reduce construction schedule Reduces borrow (no backfill of muck excavation) –

reduced truck traffic in corridor Potential to eliminate surcharge period Potential reduction in noise levels – bridge

foundations on spread footing w/ground improvements in lieu of piles

Eliminate or significantly reduce settlement

May require specialty contractor Performance specifications Risk of soil wave – outside embankment area

COST SUMMARY ESTIMATE

Original Concept $4.4 M

Recommended Concept $2.0 M for deep soil mixing

Estimated Savings $2.4 M

FHWA Functional Benefit

Safety Operations Environment Construction Other




Baseline Design All assumptions, including the base design, will require additional subsurface investigation to determine the appropriate soil remedial mythology that should be used on this project. Listed below are some alternatives that could be considered.

The base design raises TH 7 over Louisiana Ave. The current plan is to build up very large embankments on the east and west to support approaches to bridge overpass.

There is a superfund site adjacent to the project limits on the North side. It is known that some of the contaminated materials have migrated south into the project limits and are therefore under the existing TH 7 and Louisiana Ave. roadways. There is a desire to limit removal quantities and anticipated large hazmat waste costs.

Risk factors – with unknown soils, settlement and slope stability is unpredictable. The best option to minimize settlement is also the most comprehensive option: an expensive muck removal and replacement with borrow. However, this option is not necessarily the preferred option due to some constraints:

Sheet pile construction will probably be needed and slope stability might be an issue due to tight ROW

Too many unknowns – extent of muck removal – extent of contamination soils and disposal – muck removal would require extensive borrow

lots of trucks moving in and out of the project site Where would the borrow come from?

All ground improvement methods will be employed to control settlement/improve strength for the construction of the west bridge approach embankment.

Methods of Ground Improvements Deep soil mixing

Deep soil mixing has potential performance risks in peat soils,

particularly if pH is low. Deep soil mixing may be able to bind up contaminants in place

(+), but tooling and drill slurry may require specialty decontamination and disposal depending on actual environmental contaminants.

(wet) Deep soil mixing requires specialty rig, specialty contractors, and large mobilization charges; probably impractical for a small job of this size. (Dry) soil mixing may be appropriate (lime injection/stabilization), but QA is more difficult and results are generally more variable.

Probably less noisy and vibratory than pile driving; may be more desirable than pile supported embankment option.

If remediation is also used under bridge footings, shallow foundations may be used, eliminating the need for piling on the project.



Stone columns Local contractors may be only able to install to

depths of 35 feet. Settlements are likely to be reduced to levels

tolerable for roadways and minor structures; may be more than desired for bridge footings, depending on technique. (Rammed aggregate piers may have deflections suitable for bridge footings on spread footings).

Vibro-compaction Could be used in sandy areas to densify granular materials; not

appropriate for peat areas; probably not appropriate as a solution for ground improvements at the entire site. Possibly useful on the east side if bridge footings to be shallow foundations.

Blast Densification Usually used to improve density in loose sands and decrease liquefaction potential in seismic

zones. Probably not appropriate here due to proximity of business and residences. Would not address principal problem of western peat soils.

Very unlikely to be used on this project. Rarely used in urban areas at Mn/DOT due to potential damage to adjacent structures.

Dynamic [Deep] Compaction Usually used in loose or low density mineral soils. Probably not

appropriate in organic soils and peats. May have limited applicability to improve density in east and west

areas. Uses a large drop weight. Depending on soils, the stress wave

created by the drop may disturb surrounding infrastructure (utilities) in the immediate area (or create that perception) - precondition surveys of nearby structures or residences are probably necessary to protect against claims.

Design Assumptions: Borings and mechanical cone soundings from 1975/1980 used for preliminary assessment. Designs assumes that:

Soils may be contaminated



Embankments will be constructed, raising the grade, and requiring settlement mitigation

Rock is at a depth of 65 feet or greater

Peat/organic soils are present

ROW is a constraint, limiting viability of “remove and replace” options without sheeting.

Ground improvement is only needed west of Louisiana Ave. on TH 7 and ramps

Calculations: Deep Soil Mixing $120/CY installed Use 3’ diameter soil mixing 65’ deep

7.07 SF x 65’ = 459 CF / 27 = 17 CY per boring

110’ (width of roadway) x 880’ (length) =88,000 SF / 100 SF = 880 borings

880 x 17 = 14,960 CY x $120/CY = $1.795 M

Because the true extent of the muck is currently unknown, use a cost of approximately $2.0 M



PERFORMANCE MEASURES Criteria and Rating Rationale for Recommendation

Performance Original Alternative

Mainline Operations

No change from baseline

Rating 5 5

Weight 17.9

Contribution 89 89

Local Operations


Rating 5 5

Weight 17.9

Contribution 89 89

Maintainability

Anticipated settlement will be less

Rating 5 5

Weight 12.5

Contribution 63 63


Reduced excavation and construction traffic Eliminates the need for sheet pile walls

Rating 5 7

Weight 3.6

Contribution 18 25


Deep Soil mixing may encapsulate contaminated material that is present

Rating 5 6

Weight 16.1

Contribution 80 97

Project Schedule


Rating 5 5

Weight 25.0

Contribution 125 125

Risk

Eliminates risk of contaminated material & muck disposal

Rating 5 8

Weight 7.1

Contribution 36 57

Total Performance: 500 545

Net Change in Performance: 9%


VE RECOMMENDATION NO. 1b Lightweight Fill

Function: Move Earth IDEA NO(s).

3

Original Concept:

Remove contaminated soil and muck and replace with borrow. It is assumed to require temporary sheeting and shoring to maintain a stable excavation; depths are expected to be up to 35 feet for removal in west bridge area. Another assumption is that the mineral soils and organic materials that are encountered will be contaminated with coal tar, or other creosote-type products and by-products.

Recommended Concept:

Lightweight Fill: EPS Geofoam or Shredded Tires

Bridge over compressible materials with a lightweight fill embankment.

Advantages: Disadvantages Reduced settlement Reduced borrow/fill truck traffic during construction Reduces excavation of muck May reduce construction schedule Easy to construct

May complicate design of other items (need for drainage details, guardrail/moment slab.

Potential risk associated with foam/petroleum mix (contaminated soils). Robust cover requirements will be necessary.

Would preclude utilities from entering fill area.

COST SUMMARY ESTIMATE

Original Concept S4.4 M

Recommended Concept $2.2 M for EPS blocks

Estimated Savings $2.2 M

FHWA Functional Benefit

Safety Operations Environment Construction Other




Additional soils borings will be necessary to determine the proper remedial methodologies to use on this project.

Organic decay may result in long term settlement that is not adequately mitigated with lightweight fill options. These options may/should be combined with soil surcharge (pre-load) for improved performance over organic deposits that are not removed.

Some excavation will be required to provide ‘earth pressure balance’ which will provide the greatest reduction in future settlement potential.

This solution needs only to be applied in areas with increased fill (assumed on the west side approach embankment).

High water table will require that weight of soil cover is adequate to compensate for buoyant forces if EPS Geofoam is installed below 100 yr flood elevation. Three borings from 1985 show that water is approximately 2 feet below existing ground.

May wish to combine this option with cellular concrete below the water table to provide a more “inert” inclusion where there is increased risk of damage to EPS geofoam. May also be used with shredded tires.

Petroleum contamination may be a drawback to this design {EPS}, or require a more robust geomembrane liner for protection with more intense inspection at plastic joint welds.

Mn/DOT practice has been to only use shredded tires above the water table, so this option is not considered for use at this location. Another system would need to be used below water table- or risk continued deformation due to organics.

Design Assumptions: Borings and mechanical cone soundings from 1975/1980 used for preliminary assessment. Designs assumes that:

Soils may be contaminated

Embankments will be constructed, raising the grade, and requiring settlement mitigation

Rock is at a depth of 65 feet or greater

Peat/organic soils are present

ROW is a constraint, limiting viability of “remove and replace” options without sheeting.

Ground improvement is only needed on the west side of Louisiana Ave.



Sketches/Photos:

EPS Geofoam blocks being assembled

Styrofoam blocks being assembled behind retaining walls for a bridge embankment



Because of the possibility of contamination of the Styrofoam blocks from petroleum within the ground a concrete slab or other barrier should be placed between the blocks and the natural ground.

Calculations: EPS Geofoam $60/CY installed

(880’ x 110’ x 10’ average height) / 27 = 35,852 CY

35,852 CY x $60/CY = $2.15 M

Use $2.2 M



PERFORMANCE MEASURES Criteria a

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