Eagle Point Bluff Study
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MEMORANDUM
November 17, 2005
TO:
The Honorable Mayor and City Council Members
FROM:
Michael C. Van Milligen, City Manager
SUBJECT: Eagle Point Bluff Study - Results of Rock Slope Investigation
City Engineer Gus Psihoyos is recommending that a Work Session be scheduled to
discuss the results of the Eagle Point Bluff Study.
I respectfully request that the Mayor and City Council establish a date for the Work
Session. Staff will then verify availability with the consultant.
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Michael C. Van Milligen
MCVM/jh
Attachment
cc: Barry Lindahl, Corporation Counsel
Cindy Steinhauser, Assistant City Manager
Gus Psi hoyos, City Engineer
Laura Carstens, Planning Services Manager
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MEMORANDUM
November 17,2005
FROM:
Michael C. Van Milligen, City Manager
Gus Psihoyos, City Engineer _up
TO:
SUBJECT: Eagle Point Bluff Study - Results of Rock Slope Investigation
INTRODUCTION
The purpose of this memo is to transmit the findings of the Eagle Point Bluff Study -
Rock Slope Investigation performed by Kleinfelder, Inc (Bellevue, WA).
BACKGROUND
On August 2, 2004, the City Council authorized the solicitation of proposals from
qualified consulting/engineering firms for the Eagle Point Bluff Study. On December 17,
2004, the City Council endorsed the RFP for the Eagle Point Bluff Study and authorized
its release to the public. The RFP separated the project into three phases:
Phase I
The Consultant must obtain all necessary data either from City records or
site reconnaissance to thoroughly characterize the present stability of the
bluff and if the bluff is found to be unstable, the probable cause of
instability. Moreover, if the bluff is found to be unstable, the Consultant is
to draw on its experience and expertise in dealing with rock bluffs to
consider multiple stabilization techniques (such as rock removal, grouting,
bolting, etc.) and work with the City to identify which method best suits the
needs of the City.
Phase II (if necessary)
Consultant would prepare plans and specifications for the Eagle Point
Bluff Stabilization Project based on the optimum stabilization technique
identified in Phase I.
Phase III (if necessary)
Consultant would act as project engineer for the construction phase of a
stabilization project outlined in Phase II.
Page 2
The City received eight responses to the RFP. After careful review of the proposals,
presentations, review of fees, and reference checks, the proposal review committee
concluded that Kleinfelder, Inc. had the best combination of project experience, project
understanding, and project approach to best serve the City for the Eagle Point Bluff
Study.
On May 2, 2005, the City Council approved the selection of Kleinfelder, Inc. to provide
professional consulting services for the Eagle Point Bluff Study.
DISCUSSION
Kleinfelder, Inc. has completed Phase I of the Eagle Point Bluff Study and presented its
findings in two documents:
1. Eaale Point Bluff Stud v Phase I - Rock Slope Investiaation
This document is an unabridged guide to the Study and it includes the
engineering methods, testing, and analysis used to perform the bluff
investigation and establish recommendations.
2. Eaale Point Bluff Studv Phase I - Rock Slope Investiaation Citizen Guide
This document contains a condensed version of the investigation. The
technical aspects of the engineering behind the Study are not included.
Figure 1 shows the location of the part of the bluff which is the subject of the Study. It is
below Eagle Point Park and adjacent to the remnant bridge abutment near Lock and
Dam NO.11.
Fi2ure 1. Location of the Eagle Point Bluff Study.
Bluff Study Area
I
Page 3
Historical photographs show the Eagle Point Bluff tree covered except for the main high
bluff that is not part of the Study. The Eagle Point Toll Bridge was constructed circa
1901-1902 from Eagle Point on the Iowa side to Kimball's Slough on the Wisconsin side
of the Mississippi River. According to the Kleinfelder, Inc. Study, photographs taken
after the construction of the bridge show a "barren, steep rock slope" in the vicinity of
Eagle Point Bluff (see Citizen Guide, Appendix A: Photos 2-4). It appears that the bluff
was quarried and excavated to make room for the bridge. Deemed unsafe, the bridge
was torn down in 1982. The Toll Bridge Inn was constructed on the old bridge
foundation and operated as a restaurant until 2003.
Figure 2 is a photo taken in September of 2003, prior to the 2003 excavation.
In general, rock bluffs in the Dubuque area are near vertical in nature. Minor erosion
and weathering is prevalent and occasional rock falls are commonplace as witnessed at
the former quarry site just south of Eagle Point Bluff now occupied by C.R. Boats. The
Kleinfelder Study states, "because of the fractured nature of the rock mass, it is
suspected that minor rockfall occurred at the bluff (prior to the 2003 excavation)." Figure
2 shows the fractured nature of the bluff even prior to the 2003 excavation.
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Page 4
The Kleinfelder Study concludes that there is now a high level of risk of a large-scale
failure on some parts of the bluff. The risk has been increased because of the 2003
excavation that steepened the slope from 75 to 80 degrees and increased the height
from 35 to 60 feet. While the Study finds no fault with the blasting operations on the
bluff, striking the rock face with a track hoe and wrecking ball "exacerbated the
instability of the rock slope." Figure 3 shows the wrecking ball hitting the rock face.
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The Kleinfelder Study presents multiple stabilization options for the bluff stabilization
depending on whether the use of the property below the bluff is commercial, residential,
or undeveloped. Although stabilization is recommended for all three uses, more
additional measures are recommended if the site is developed for commercial or
residential use. Options include controlled blasting, slopes scaling, rock bolts, horizontal
drains, and wire mesh slope protection. The construction cost estimates range from
$80,000 to $250,000.
The City Manager, the Corporation Counsel, and Engineering staff have begun
identifying potential actions that the City could take based on the Study findings. The
following list of actions is offered for consideration:
Page 2
The City received eight responses to the RFP. After careful review of the proposals,
presentations, review of fees, and reference checks, the proposal review committee
concluded that Kleinfelder, Inc. had the best combination of project experience, project
understanding, and project approach to best serve the City for the Eagle Point Bluff
Study.
On May 2, 2005, the City Council approved the selection of Kleinfelder, Inc. to provide
professional consulting services for the Eagle Point Bluff Study.
DISCUSSION
Kleinfelder, Inc. has completed Phase I of the Eagle Point Bluff Study and presented its
findings in two documents:
1. Eaqle Point Bluff Studv Phase I - Rock Slope Investiqation
This document is an unabridged guide to the Study and it includes the
engineering methods, testing, and analysis used to perform the bluff
investigation and establish recommendations.
2. Eaqle Point Bluff Studv Phase I - Rock Slope Investiqation Citizen Guide
This document contains a condensed version of the investigation. The
technical aspects of the engineering behind the Study are not included.
Figure 1 shows the location of the part of the bluff which is the subject of the Study. It is
below Eagle Point Park and adjacent to the remnant bridge abutment near Lock and
Dam No. 11.
Fig~e 1. Location of the Eagle Point Bluff Study.
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Bluff Study Area
I
Page 3
Historical photographs show the Eagle Point Bluff tree covered except for the main high
bluff that is not part of the Study. The Eagle Point Toll Bridge was constructed circa
1901-1902 from Eagle Point on the Iowa side to Kimball's Slough on the Wisconsin side
of the Mississippi River. According to the Kleinfelder, Inc. Study, photographs taken
after the construction of the bridge show a "barren, steep rock slope" in the vicinity of
Eagle Point Bluff (see Citizen Guide, Appendix A: Photos 2-4). It appears that the bluff
was quarried and excavated to make room for the bridge. Deemed unsafe, the bridge
was torn down in 1982. The Toll Bridge Inn was constructed on the old bridge
foundation and operated as a restaurant until 2003.
Figure 2 is a photo taken in September of 2003, prior to the 2003 excavation.
In general, rock bluffs in the Dubuque area are near vertical in nature. Minor erosion
and weathering is prevalent and occasional rock falls are commonplace as witnessed at
the former quarry site just south of Eagle Point Bluff now occupied by C.R. Boats. The
Kleinfelder Study states, "because of the fractured nature of the rock mass, it is
suspected that minor rockfall occurred at the bluff (prior to the 2003 excavation)." Figure
2 shows the fractured nature of the bluff even prior to the 2003 excavation.
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Page 4
The Kleinfelder Study concludes that there is now a high level of risk of a large-scale
failure on some parts of the bluff. The risk has been increased because of the 2003
excavation that steepened the slope from 75 to 80 degrees and increased the height
from 35 to 60 feet. While the Study finds no fault with the blasting operations on the
bluff, striking the rock face with a track hoe and wrecking ball "exacerbated the
instability of the rock slope." Figure 3 shows the wrecking ball hitting the rock face.
The Kleinfelder Study presents multiple stabilization options for the bluff stabilization
depending on whether the use of the property below the bluff is commercial, residential,
or undeveloped. Although stabilization is recommended for all three uses, more
additional measures are recommended if the site is developed for commercial or
residential use. Options include controlled blasting, slopes scaling, rock bolts, horizontal
drains, and wire mesh slope protection. The construction cost estimates range from
$80,000 to $250,000.
The City Manager, the Corporation Counsel, and Engineering staff have begun
identifying potential actions that the City could take based on the Study findings. The
following list of actions is offered for consideration:
Page 5
1) Budget funds for a stabilization project by the City;
2) Explore the possibility of collaborating on the stabilization project with the
developer;
3) Consider declaring the risk of falling rock a public nuisance and requesting
the developer to install a fence to keep the public away from the area and
require implementation of one of the recommended stabilization methods
outlined by the Kleinfelder Study if and when the property is developed for
commercial or residential use.
This list is only offered as a starting point for discussions that will lead to the appropriate
response to the findings presented in the Eagle Point Bluff Study.
RECOMMENDATION
I recommend that the City Council schedule a work session at which time Dr. William
Gates of Kleinfelder, Inc. would present and discuss the Eagle Point Bluff Study.
BUDGET IMPACT
Phase I of the stabilization study has been completed at a cost of $49,800. If a
stabilization project is considered, the estimated costs are:
Engineering $ 45,000
(Phase II as outlined in the RFP)
Construction Observation $ 55,000
(Phase III)
Estimate Subtotal $100,000
Project Construction $ 80,000 - $250,000
(Dependent on Stabilization Method Used)
Total Project Estimate $180,000 - $350,000
ACTION TO BE TAKEN
I respectfully request the City Council be requested to schedule a work session to allow
Dr. William Gates of Kleinfelder, Inc. to present and discuss the Eagle Point Bluff Study.
Prepared by Deron Muehring
cc: Barry Lindahl, Corporation Counsel
Cindy Steinhauser, Assistant City Manager
Laura Carstens, Planning Services Manager
Bob Schiesl, Assistant City Engineer
Deron Muehring, Civil Engineer II
November 21, 2005
Ms. Jeanne Schneider
City Clerk
City Hall
Dubuque, Iowa 52001
Re: Work Session - Eagle Point Bluff
Dubuque City Council Agenda
November 21, 2005
Dear Ms. Schneider:
Due to the fact that I received my copy of the November 21,2005 Council
Agenda on Saturday November 19,2005, I apologize for this late request. Briefly
I am requesting that a representative from Preserve Our Bluffs be appointed to
attend any Work Sessions on Eagle Point Bluff requested by Mr. van Milligan and
eventually decreed by the City Council. Thank you.
With Kindness,
5,/~
S.A. Sutton
1875 Custer
Dubuque, Iowa 52001