Item 2AAGENDA ITEM # 2A
MARCH 24, 2008
City of Atlantic Beach
Royal Palms Stomw~rater Preliminary Engineering Report
EXECUTIVE SUMMARY
Constructed nearly 40 years ago, the stormwater infrastructure in the Royal Palms subdivision
is deteriorating at an ever-increasing pace. Two recent pavement failures illustrate the poor
condition of the collection and conveyance systems. Without systematic rehabilitation, the City
of Atlantic Beach's maintenance crews will likely become overwhelmed managing repairs to the
systems in this neighbofiood. Significant lengths of pipe exist in easements on private
property, and homeowner improvements (e.g., out-buildings, fences, and pools) constructed in
these easements encumber maintenance access to the aging infrastructure.
To address these issues, Applied Technology & Management, Inc (ATM) worked with City staff
to develop conceptual design altematives. Initially, the City asked ATM to evaluate removal of
all stormwater pipes from within easements. ATM reviewed the City's existing data on the
system, collected limited topographical survey data, and conducted a closed circuit television
(CCTV inspection of a portion of the existing stormwater infrastructure.
This evaluation resulted in Altemative 1, where most existing pipes would be relocated from the
easements into the public right-of--way. As a result, a large amount of existing residential
roadway pavement within the subdivision would be impacted and require replacement. This
approach to the problems resulted in a significant capital cost of $4,400,000 in 2008 dollars.
Concurrently, the City requested that ATM separately evaluate the cost of replacing an asbestos
concrete (AC) watertine on Plaza Street and to provide additional pavement, curb, and gutter
improvements in areas not impacted by construction. With these improvements being
constructed at the same time as the stormwater infrastructure improvements, the City saw a
potential opportunity to realize significant cost savings for the surface improvements. The cost
for these additional surface improvements is approximately $1,920,000 in 2008 dollars and
would be paid from a separate funding source.
Effectively maintaining the continuously deteriorating stormwater system in the Royal Palms
subdivision may become anever-ending job for the Public Works Department field crews.
However, there are no significant drainage problems in the subdivision. Therefore, while
implementing Alternative 1 is desirable from a management perspective, the ratio of
effectiveness to cost of improvement is low and is somewhat difficult to justify if other
altematives could provide a higher ratio of effectiveness to cost.
ATM evaluated two additional altematives to optimize the effectiveness to cost ratio. Altemative
2 considers complete rehabilitation of the pipes in-place and installation of new drainage
structures. A rehabilitated system will significantly reduce maintenance costs, but does not
remove the pipes from the easements. Altemative 3 provides a combination of the other
alternatives by replacing targeted pipes, rehabilitating others, and replacing all non-precast
Applied Technology 8 Management, Inc.
March 2008
AGENDA ITEM # 2A
MARCH 24, 2008
City of Atlantic Beach
Royal Palms stormwater Preliminary Engineering Report
drainage structures. Alternatives 2 and 3 result in a rehabilitated system that provides a higher
cost effectiveness than would be achieved by adopting Alternative 1.
To evaluate which Alternative to recommend, ATM developed a prioritization matrix that weighs
the various considerations that affect the decision making process (cost, design life,
neighborhood inconvenience, etc.) for each alternative. The considerations used in the matrix
are those typically used for engineering decisions on similarly scoped stormwater retrofit
projects and are based on ATM's engineering judgment and discussions with City staff.
The table below summarizes the results of the prioritization matrices and the engineer's opinion
of probable construction cost for each alternative. Note that for Alternative 1, only the costs
relating to the direct impacts of the stormwater improvements are shown. While the costs for
the other surface improvements are related, they are a separate issue, and budgets for those
improvements will be funded separately.
Evaluation Results
Parameter Prioritization
Matrix Score' Capital Cost
S x 1,000,000
Altemative 1 21.5 $ 4.40
Altemative 2 23.6 $ 3.00
Altemative 3 24.2 $ 3.50
1-Highest score represents the altemative that best meets the considerations
deemed im rtant to this
2 -Capital costs are based on 2008 construction costs and do not include
e ineerin admiMe al costs
The results of this evaluation and prioritization show that Alternative 3 best addresses the
considerations deemed important to this project. Therefore, we recommend that the City
proceed with the design recommendations of Alternative 3, which provides a combination of
replacement and rehabilitation of stormwater pipes in the Royal Palms subdivision in four (4)
phases. ATM has developed a draft Scope of Services necessary to complete the project
through Final Design and Construction.
The Scope of Services for executing Final Design and Construction includes the following
general tasks: detailed vertical and horizontal topographic survey; completion of the CCTV
inspection of the entire system; geotechnical evaluations; calculation of the hydraulic grade line
from the outfall to the upstream terminus for each branch in each system; a more in-depth pipe-
by-pipe analysis of the feasibility of the recommended trenchless technologies for rehabilitation;
preparation of construction drawings and details; utility relocation details; preparation of the
ii
Applied Technology 8~ Management, Inc.
March 2008
AGENDA ITEM # 2A
MARCH 24, 2008
City of Atlantic Beach
Royal Palms Stormwater Preliminary Engineering Report
General Stormwater ERP Permit Application; preparation of Final Engineer's Opinion of
Probable Construction Costs; preparation of construction documents; bidding phase services;
shop drawing review; and other construction phase administrative and inspection services.
During this evaluation, ATM and the City met with the St. Johns River Water Management
District (SJRWMD) to conduct a permitting pre-application meeting. Based on the meeting,
significant permitting issues are not expected with this project.
ATM also evaluated potential outside funding opportunities such as grants or appropriations for
this project. The hydraulic constraints of the project limit the opportunities to install traditional
structural BMPs that might improve water quality. However, ATM considers the entire project to
be a water quality BMP since replacement or rehabilitation of pipe alignments or pipes will
reduce sediment transport to downstream areas. For each phase of the project, the City may
apply for SJRWMD Cost-Share funds. Since the project is not a traditional water quality
improvement project, however, it may rank poorly among other projects competing for the same
funding.
Applied Technology 8~ Management, Inc.
March 2008
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