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LTC 268-2018 Storm Event of Sunday Evening May 13, 2018MIAMIBEACH City of Miami Beach, 1700 Convention Center Drive, Miami Beach, Florida 33139, www.miamibeachfl gov Jimmy L. Morales, City Manager Tel: 305-673-7010 , Fax: 305-673-7782 NO. LTC # 268-2018 LET ER TO COMMISSION TO: Mayor Dan Gelber and Members of t e City Co mission FROM: Jimmy L. Morales, City Manager DATE: May 15, 2018 SUBJECT: Storm Event of Sunday Evening, ay 13, 2018 The purpose of this Letter to Commission is to provide information to the Mayor and City Commission regarding the storm event of Sunday night. The City has a rain gauge located at City Hall which recorded a total of 4.09 inches of rain for the 24 hour period ending at 12:00 am May 14, 2018. Between the hours of 6:00 pm and 7:00 pm, 1.88 inches of rain fell with a peak intensity of 8.11 inches per hour. During the time of the heaviest rains and immediately afterwards, some localized flooding was observed at various locations throughout the City. In Sunset Harbour on Sunday evening, some properties that are located below the flood plain elevation reported minor flooding for a brief period of time. The storm water system built in Sunset Harbour by Lanzo Construction Company was expected to prevent sunny day flooding due to sea level rise and manage six (6) inches of rain in 24 hours with a peak hourly capacity of 2.4 inches. The improvements have proven to work very well against sea level rise as we have not seen any sunny day flooding in the area which had been frequently the case during higher tidal events. All information available shows the system will easily manage the 6 inches of rainfall in 24 hours. However, the system, in at least some locations, reaches capacity at approximately 1.8 inches in one hour. City staff, consultant engineers from AECOM, and Lanzo Construction Company with their engineers from Wade Trim, have been engaged for months making this determination. Lanzo Construction Company owner, Joe D'Alessandro Sr., has provided his commitment to the City of Miami Beach to make improvements in the system to be sure expectations are met. Lanzo Construction Company is expected to provide submittals for engineering review of their intended improvements. Work is expected to commence very shortly. If the City experiences rainfall events that exceed 1.8 inches per hour, exceeding the system capacity, properties that are below the flood plain elevation may experience standing water for a short amount of time. Should you have any questions, please contact myself or Roy Coley at 305-673-7080.