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, <br />) <br />) <br />) <br />) <br />) <br />) <br />) <br />) <br />) <br /> <br />) <br />) <br />) <br />~ ) <br />) <br />) <br />) <br />) <br />) <br />) <br />) <br />) <br />) <br />) <br />) <br />) <br />) <br />) <br /> <br /> <br />TOWN OF SURFSIDE STORMWATER DRAINAGE <br />Surfside, Florida <br /> <br /> <br />The Town of Surfside was incorporated on May 18, 1935 and it encompasses a total land <br />area of approximately 330 acres. The Town is built out with no land for traditional <br />treatment BMPs. Storm water runoff flows down gridded streets from east to west with <br />no storm water treatment facilities in the Town. Runoff flows out to the Bay via pump <br />station and six injection wells at each outfall at 92nd and 88th Streets.. The residential <br />areas are so low that the ground water is only about 1.5 feet below the surface, <br />eliminating the use of exfiltration trench for water quality purposes. During high tides the <br />Bay backs up through the storm drain gravity system and into the streets, creating a <br />surcharged system. All of the Bay frontage properties in the town have seawalls. <br /> <br />CGA developed the Town of Surfside Storm water Management Master Plan to address <br />water quality issues and reduce flooding within the Town. The Master Plan included a <br />complete engineering analysis based on the ICPR computer models of the storm water <br />management system. From a water quality perspective, CGA formulated the best <br />approach to reduce or eliminate pollutant discharge loadings into Biscayne Bay from <br />the Town's system. In addition, the modeling targeted improvement in hydraulic <br />performance of the Town's drainage system. <br /> <br />Based on the site location, proposed site grades, water table depth, and surficial aquifer <br />depth the drainage wells operated by pumps were found to be the most practical option. <br />The project retrofitted the existing Town's outfalls with storm water treatment facilities <br />reducing pollutants in storm water runoff entering Biscayne Bay. The 24 inch diameter <br />gravity drainage wells are fed by storm water pump stations. The capacity of pump <br />station required to serve drainage wells have been calculated based on the total design <br />maximum capacity of the wells. <br /> <br />The proposed drainage wells also reduced the post-condition peak discharge. Due to <br />space restrictions the proposed pump stations and injection wells were located in the <br />Town Street ROW limits. Storm water runoff is pumped into the drainage well with the <br />following conditions: <br /> <br />1. The proposed inflow pipe to the pump station will have Pollution Separating <br />Baffle Box and the pump station will have control structure to separate the <br />suspended particles before pumping into the drainage well. <br />2. The maximum allowable head is limited to 8ft. NGVD as the attached by-pass <br />pipe is raised at 8 ft. N.G.V.D. <br />3. The discharge into the aquifer will take place by gravity flow only. <br />4. The fresh water and salt water concentration difference has been taken into <br />consideration to calculate equalization head for the wells. Gravity drainage well <br />capacity is 700 GPM per foot of head. The pump is selected based on the <br />combined capacity of 3 (three) drainage wells <br /> <br />11-4260_ Surfside Drainage Improvements <br /> <br />Client <br />Town of Surfside <br /> <br />Contact Information <br />Roger Carlton <br />Town Manager <br />9293 Harding Avenue <br />Surfside, Florida 33154 <br />(305) 861-4863 <br /> <br />Project Date <br />2008-2011 <br /> <br />Services Provided <br />Engineering <br />Surveying <br />Permitting <br />Planning <br />GIS <br />Landscape Architecture <br />Construction Services <br />Emergency Management <br /> <br />Principal in Charge <br />Karl Kennedy, PE <br /> <br />Project Administrator <br />John Messerian, PE <br /> <br />Drainage Engineers <br />Robert McSweeney, PE <br />Douglas Taylor, PE <br /> <br />Surveyors <br />Robert Jackson, PSM <br />Greg Clements, PSM <br /> <br />Civil Engineers <br />Luis Pimentel, El <br /> <br />Construction Cost <br />$2,100,000 <br /> <br />Consultant Cost <br />$399,500.00 <br /> <br />Firm's Role <br />Prime <br /> <br />Page 21 7 <br />