ANALYSIS:
The Orchard Park neighborhood, which includes 44th Street and Post Avenue intersection, suffers from a flawed drainage system installed in 2011. The stormwater drainage inlets are as low as 1.04 NAVD and are designed to drain into a “French Drain” (exfiltration trench). The geology and hydrology of our barrier island coupled with the increasing level of the ground water which mirrors that of Biscayne Bay have resulted in the ineffectiveness of this system. It is common during the spring and fall “King Tides” for the tidal elevation to exceed these local elevations. During these tides, and especially when it rains during higher tides, water pools in the street impeding safe passage.
ANALYSIS
During recent "King Tides" the City installed temporary pumps to help reduce the flooding risk. The cost of temporary pumps is significant and has been limited to high risk times. The primary pump that proved beneficial was located in Muss Park which was under construction at the time. Muss Park is now open for usage by the public and temporary pumps and discharge hoses will inconvenience those planned recreational activities there.
Interim measures are planned for the upcoming spring high tides. A “back flow” prevention device, or one way flow control device, is to be installed on the outfall of the main drainage pipe that leads from 44th Street into the adjacent canal. This device allows water to drain to the canal when the tides are lower than the street and stop the canal from flowing into the stormwater draining system at times when the tides are higher than the discharge elevation. Temporary pumps are currently planned for usage during these times to remove stormwater collected from rain events.
More permanent measures are being evaluated and considered to mitigate against sea level rise for this neighborhood. The City’s engineering team is working to evaluate the needs based on the recent direction to consider ten (10) year storm events versus the five (5) year storm event previously used planning criteria previously used. Once pumping capacities and piping sizing requirements are determined the process of determining the appropriate location of permanent pumps will follow. Additionally, it is expected that other recommendations will be made and considered to aid the mitigation such as raising the street elevation.
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