To meet its stormwater needs, the City of Miami Beach is investing over $650 Million in various infrastructure improvements, over an estimated span of 10 years. The infrastructure improvements include installing larger pipes, building pump stations, and raising roads to ensure that the roads do not flood in future tidal and rainfall events.

During King Tide events, to prevent localized street flooding in low areas such as upper North Bay Road, Orchard Park, Indian Creek, Tatum Waterway, and other North Beach areas, temporary pumps have been installed to assist in mitigating standing water.

At its January 27, 2020 Commission Workshop on Resilience, the Public Works Department offered the Commissioners a presentation on temporary pumps (attached), which depicts citywide locations where temporary pumps were to be deployed.

Two scenarios were offered to the Commissioners for discussion: A 14 pump deployment (which would allow for some standing water to remain, as recommended by the Urban Land Institute) or a 28 pump deployment (which would provide a higher level of service), to be tested for a period of six months at a cost of $454,000 or $890,000 respectively.

At its February 18, 2020 meeting, the Land Use and Sustainability Committee (LUSC) held a discussion regarding properties in areas that continuously flood during rain events or King Tides.  While there is a resilience program that will identify these needs, many neighborhoods will not be improved until a later date. Committee members inquired whether there was an interim solution for such homes, perhaps with the inclusion of blue/green initiatives.  The Public Works Department offered alternatives to be considered for discussion.

At the end of the discussion, the Committee made a motion to bring forth a plan, a list of locations where blue/green infrastructure solutions may be applied to, a ballpark cost and funding alternatives for these initiatives and to bring it back to the Committee. It was noted that these initiatives would be in addition to the proposed 14 pump deployment.

At the May 6, 2020 meeting of the LUSC, Public Works presented its members a blue/green infrastructure (bioswale) pilot program for consideration. The target area for this pilot program would be a residence at the LaGorce Neighborhood, an area known to flood during heavy rain due to its low lying elevation.

The Committee members were in agreement with the pilot program and made a motion to have Public Works to proceed with the bioswale; to bring the item to the full Commission for approval, and upon implementation, to come back to Committee before moving onto other recommended bioswale locations.

BLUE/GREEN INFRASTRUCTURE

A typical blue/green infrastructure installed within the right-of-way is a manmade swale (bioswale) typically vegetated and/or mulched with engineering soils below the surface.  It can improve water quality by allowing water to collect naturally in the bioswale depressions and drain through the engineered soils beneath the surface rather than passing into storm sewers.  It is designed to capture the first 1.5 inches of rainfall during storm events.

The City is considering implementing a pilot project as means to test the efficacy and value of this type of technology. 

A bioswale can provide the following benefits and limitations:

The request to approve the pilot program was scheduled to be presented at the June 24, 2020 City Commission, however, following the LUSC motion on May 6, 2020, the owners of the residence selected for the pilot program opted out.  Instead, the owners expressed an interest in having an impervious drainage structure installed to route stormwater into the existing drainage collection system.

Public Works staff is currently evaluating a second residence in the North Bay Road neighborhood also known to flood, that could be a potential bioswale pilot program recipient.  Following the property's assessment, and owner's consent of the bioswale pilot program, Public Works will present the second location to the City Commission for approval.  Meanwhile, since the second location was not what was originally approved by the LUSC members, Public Works is bringing the item back to Committee for review and approval to proceed.  The estimated cost for the installation of the blue/green infrastructure can run anywhere from $15,000 to $30,000 per property, depending on the size of the swale. 

Results from the 2019 Resident Survey show that 50% of residents rated efforts to manage stormwater drainage and flooding as excellent/good, and 59% of residents rated Stormwater & drainage improvements as excellent/good.  In order to continue maintaining excellent standards in this area, the City is considering additional locations prone to flooding during heavy rain that may be eligible for a blue/green infrastructure (bioswale).

The Administration recommends that the Land Use and Sustainability Committee members consider an alternate location for a potential blue/green infrastructure (bioswale) pilot program since the original recipients opted out, and if in agreement, approve to proceed with the installation.