LTC 131-2008 GO Bond Street Improvement Project on Star Islandm MIAMIBEACH
OFFICE OF THE CITY MANAGER
NO. LTC # 131-2008
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LETTER TO COMMISSION
TO: Mayor Matti Herrera Bower and Members of the ~ Commission
FROM: Jorge M. Gonzalez, City Manager
DATE: May 5, 2008
SUBJECT: GO Bond Street Improvement Project on Star Island
This letter to the Commission is in response to referrals from several of your offices
regarding the GO Bond Street Improvement Program on Star Island. The current scope of
work as defined in the Basis of Design Report (BODR) consists of the following:
^ Milling and resurfacing the roadway
^ Positioning landscape lighting at the entrance and circle palm areas
^ Replacing and upgrading the water mains from six-inch to eight-inch diameter
^ Installing concrete pavers at the entry
^ Installing six-inch flush curbs on both sides of the roadway
The City has attempted to minimize the impact of construction on the driveway and curb
encroachments by aligning the proposed six-inch flush curbs within the existing asphalt,
which will require the removal or modification of only a small portion of the encroachments.
Some residents are concerned the current plans for the project will not alleviate perceived
drainage problems on the Island. The current stormwater system on Star Island is typical for
residential areas. Star Island East and West Drives have center crowns that drain half of the
stormwater inward toward the median /green space area and half outward toward the
swales that abut the homes. However, over the years, some residents have built up the City
owned swales with landscaping and raised curbs. These encroachments impede drainage to
the swales and cause some ponding on the roads.
Star Island is not in a stormwater Priority Basin and there are currently no funds allocated for
the project to address drainage issues. Should the Commission wish to address drainage on
Star Island, there are two options that do not impact the swale encroachments.
The first option adds inlets with drainage piping at low points adjacent to the street. These
improvements would be connected to the existing stormwater system draining into the
existing outfall. This solution is estimated to cost between $125,000 and $250,000.
This option does not address the 5-year 1-day storm event; it reduces the spot drainage
problems caused by the encroachments in the swales. This is seen as an acceptable option
LTC -Star Island Drainage GO Bond Program
May 5, 2008
Page 2 of 2
as Star Island is not a Stormwater Priority Basin
It should be noted that most residents would prefer to solve the Stormwater issue by a more
extensive option. This involves sloping the entire street toward the median /green space
area and leaving swale areas and encroachments undisturbed. Should the Commission
wish to pursue this option, the consultant would need to redesign the street and median.
This would require rebuilding the profile of the street and changing the slope to the median.
The median would also have to be re-graded to detain /retain more stormwater.
This option would require the creation of additional drawings and new calculations to
determine the area's size and ability to cope with a significant quantity of storm water.
Further, the median contains a number of piping systems including water, sewer, gas, and
irrigation that would have to be considered by the consultant during design.
Additional construction and soft costs would have to be established, as they are not currently
included in the project budget. Based on preliminary estimates, reconstruction of the street
base, resurfacing the roadway, and re-grading the median would require the allocation of
$500,000 to $600,000 in additional funding, including soft costs.
No other options remain under the BODR defined and budgeted scope of work, unless staff
is directed to remove the encroachments or to establish a new approach to storm drainage
by installing swell-based system. In order for storm water drainage to be improved without
installing a well system, the right-of-way encroachments, including all of the raised curbs and
mounds, would have to be removed to recover the swales for drainage. Awell-based
system, like the second option, would require additional drawings and new calculations.
While option one appears to have the least impact and is the least costly alternative, none of
these potential improvements have been included in the project discussions or the project
budget, and they are not currently incorporated in the scope of work.
The policy of the Commission has been to not increase the scope and cost in non-priority
basin ROW projects, as this could lead to a situation where neighborhoods are competing
against other neighborhoods for very scarce stormwater funds.
I hope this information clarifies this issue. Should you require additional information, please
do not hesitate to contact me.
JMGITH\JECh
c: Tim Hemstreet, Assistant City Manager
Jorge Chartrand, CIP Director
F:lcmgr\$ALLILTC-08U.TC Star Island Drainage GO Bond Program 5-5-08.doc