Memorandum. AECOM Technical Services Inc. Page 1

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Roy Perkins
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1 Memorandum To: Gregg R. Strakaluse, P.E. and Andy Holland, P.E. From: Ronald Cavalieri, P.E. Prepared By: Reshma Thummadi, P.E. Date: September 20, 2013 Subject: Permitting of Subaqueous Stormwater Outfalls in Florida The City of Naples (City) stormwater drainage system consists of a series of catch basins and pipes that collect and convey stormwater to the Gulf of Mexico and other tidal water bodies within the City. The stormwater drainage system is subdivided into 12 Drainage Basins. The City s Stormwater Drainage Basin II, which is one of the City s main basins has ten (10) stormwater outfalls (numbered 1 through 10) discharging to the Gulf of Mexico along Naples Beach. The City is currently investigating alternatives for reducing or eliminating stormwater discharge flows from the outfalls in order to address concerns related to beach erosion, turtle nesting habitat impacts, lateral beach access interference, water quality degradation, and aesthetics of the beach environment. Naples beaches consist of long expanses of fine white sand, offering spectacular Gulf views and fantastic sunsets, and are a worldwide attraction to seasonal residents and tourists. Preservation and protection of the City s beaches is critically important to the City. As part of this effort, the City selected AECOM Technical Services Inc. (AECOM) to perform the City s Beach Stormwater Outfall Management Evaluation. AECOM prepared Development of Alternatives and Preliminary Assessment Technical Memorandum for the City s Beach Stormwater Outfall Management Evaluation in April The Technical Memorandum identified a series of alternatives that considered measures within the drainage basin to reduce the impacts of the outfalls on the beach while maintaining the same level of service as compared to the existing conditions. The alternatives included the following: 1. Integration of beach outfalls with planned beach re-nourishment project 2. Integration of beach outfalls with Aquifer Storage and Recovery (ASR) system 3. Consolidation of beach outfall pipes 4. Redirection of beach outfall flows via pump station to alternate location 5. Consolidation and extension of beach outfalls deeper and further into Gulf of Mexico (Subaqueous Outfalls) The City requested AECOM to further investigate the feasibility for permitting and construction of Subaqueous Outfalls based on history of utilities in the State of Florida that already have constructed such stormwater outfalls. Accordingly, AECOM contacted the Florida Department of Environmental Department (FDEP) to identify utilities in the State of Florida that already have such stormwater outfalls. AECOM contacted the utilities that were referred by FDEP, which considered Subaqueous Outfalls. AECOM Technical Services Inc. Page 1

2 This technical memorandum summarizes the feedback received from FDEP and other utilities regarding Subaqueous Outfalls. Design and Construction of Subaqueous Outfalls Many factors need to be considered in the design of an ocean outfall system to ensure that the outfall survives as a structural system in the ocean environment and also meets water quality requirements. Components of Subaqueous Outfall design include: 1. Outfall Diameter 2. Outfall Depth 3. Outfall Length 4. Navigation Markers 5. Hydrostatic Head 6. Structural Stability 7. Outfall Buoyancy 8. Sea Floor Movement 9. Stormwater Dilution 10. Bio-fouling 11. Assessment of Environmental Impacts Detailed discussion of the above components is provided in Section 2 of the City s Development of Alternatives and Preliminary Assessment Technical Memorandum for the City s Beach Stormwater Outfall Management Evaluation (April 2013). Final design of the Subaqueous Outfalls involves components such as foundation requirements, external pipe forces, hydraulic flow properties, corrosion resistance, pipe material selection, pipe support systems, and selection of construction methods. Each of the above components must be evaluated during the design of an ocean outfall. The difficulty and cost of construction of Subaqueous Outfalls depends on the method of construction of the pipeline. The appropriate method of construction for an outfall pipe depends on many factors including soil conditions, pipe material and size, environmental conditions, depth of construction, contractor's available equipment, and final design conditions. All of these factors are involved in determining the cost of the final installation. A major factor related to cost of outfall construction is the amount of underwater work required, particularly work performed in deep water. The degree of difficulty, time required, and, therefore, costs increase greatly as the depth of water increases. During the design of a Subaqueous Outfall, provisions for inspection and maintenance of the outfall should be considered. Even carefully designed outfalls will require occasional cleaning to remove accumulated grease, slime, and grit. These accumulations can reduce flow by increasing frictional resistance. In addition to cleaning operations, an annual diving inspection of the outfall may be required for inspection of the outfall to assess structural damage, pipe corrosion, changes in biological activity, and any plugging. AECOM Technical Services Inc. Page 2

3 Permitting for Subaqueous Outfalls Subaqueous stormwater discharge pipelines are not common in the State of Florida, creating unique permitting challenges for the construction of such an outfall. Construction of Subaqueous Outfalls would require coordination with different permitting agencies including the following: 1. Water Management District (WMD) 2. Florida Department of Environmental Protections (FDEP) 3. U.S Army Corps of Engineers AECOM contacted (via. phone) the above permitting agencies regarding permitting requirements for Subaqueous Outfalls. The following includes a summary of feedback received through discussion with the permitting agencies. Construction and operation of Subaqueous Outfalls would require an Environmental Resource Permit from the WMD. Construction and operation of Subaqueous Outfalls that extend more than 1,600 feet into Gulf of Mexico would require a permit from U.S Army Corps of Engineers. It was indicated by U.S. Army Corps of Engineer s that anything less than 1,600 feet would not come under U.S Army Corps of Engineer s jurisdiction but would be administered by the FDEP s Bureau of Beaches and Coastal Systems. FDEP permits that are required for construction and operation of Subaqueous Outfalls are listed below. Based on final design of Subaqueous Outfalls, some or all of the following permits might be required for construction and operation of the outfall. The contact phone numbers of FDEP s personnel dealing with respective permits is also provided below. o FDEP s National Pollutant Discharge Elimination System (NPDES) Permit [Contact: Alan ] o FDEP s Bureau of Beaches and Coastal Systems - Joint Coastal Permit [Contact: Martin ] o FDEP s Bureau of Beaches and Coastal Systems - Submerged Lands Permit [Contact: Doug ] o FDEP s Coastal Construction Control Line Permit (CCCL) [Contact: Molly ] Construction and operation of Subaqueous Outfalls would require coordination and approval from the U.S. Coast Guard. Construction and operation of Subaqueous Outfalls could require local City and County approvals related to local ordinances. AECOM Technical Services Inc. Page 3

4 Permitted Subaqueous Outfalls in State of Florida According to Mr. Alan Hubbard with FDEP s NPDES Permitting Department, to date, only one utility has a Permitted Subaqueous Outfall in the State of Florida, which is Sarasota County. Another utility, City of Venice, has a pending permit application with FDEP for construction of a Subaqueous Outfall. AECOM contacted Sarasota County s stormwater engineer Mr. Curtis Smith ( ) and the following is a summary of feedback received from Sarasota County regarding the County s Subaqueous Outfall. 1. The location of the outfall is Siesta Key in Sarasota County. 2. The outfall is currently under construction. 3. The outfall includes a 16-inch pipeline that extends approximately 2,400 feet and discharges stormwater to a deep water location into the Gulf of Mexico. 4. The construction work for the project includes offshore horizontal directional drilling, and a stormwater discharge pipeline, diffuser, and anchoring system. 5. The following are the permits that were obtained by Sarasota County for construction and operation of the Subaqueous Outfall: a. Environmental Resource Permit from Southwest Florida Water Management District b. NPDES Permit from FDEP c. CCCL Permit from FDEP s Bureau of Beaches and Coastal Systems. d. U.S. Army Corps of Engineer s Permit e. Approval from U.S. Coast Guard f. County approval related to Gulf Beach Setback Ordinance 6. The construction cost of the project is $4.5 Million (bid price). Sarasota County has partial funding (about $1.0 Million) from Southwest Florida Water Management District for the construction of this project. 7. The purpose of the project was to alleviate the County s flooding problems and periodic water quality violations at a top Florida tourist beach on Siesta Key. AECOM contacted the City of Venice stormwater engineer Mr. James Smith ( ext ) and the following is a summary of feedback received from the City of Venice regarding City s Subaqueous Outfall. 1. The locations of the outfalls include Flamingo Ditch and Deerfield Gully in the City of Venice. 2. The City has completed final design on the outfalls. The construction of the project is currently on hold due lack of funding. 3. The Flamingo Ditch outfall includes dual 24-inch pipelines that extend approximately 1,192 feet and discharges stormwater to a deep water location (depth of approximately 16 feet NAVD) into the Gulf of Mexico. 4. The Deerfield Gully outfall also includes dual 24-inch pipelines that extend approximately 1,160 feet and discharges stormwater to a deep water location (depth of approximately 16 feet NAVD) into the Gulf of Mexico. AECOM Technical Services Inc. Page 4

5 5. The following are the permits that were obtained by the City of Venice for construction of the Subaqueous Outfall: a. Environmental Resource Permit from Southwest Florida Water Management District b. NPDES Permit from FDEP (pending approval). The project is currently on hold for lack of funding, but has no issues with regard to permitting (subject to review). 6. The project goals and objectives are to improve water quality and to reduce flooding in areas of the City. Permitted Subaqueous Outfalls outside State of Florida that discharge to Atlantic Ocean Literature search for utilities with permitted subaqueous outfalls that discharge to Atlantic Ocean showed that South Carolina s Grand Strand Communities (Beaches between Little River & Georgetown) have constructed stormwater outfalls that discharge further out and deeper into the Atlantic Ocean. 1. The location of the outfall includes Myrtle Beach in South Carolina. 2. The outfall includes 3 outfall pipelines that extend approximately 1,000 feet and discharges stormwater to a deep water location into the Atlantic Ocean. 3. The purpose of the project is to limit beach erosion and reduce localized pollution concentrations for swimmers. Reference: South Carolina 9th in Beach Water Quality Article by Natural Resources Defense Council Testing the Waters Conclusions Permitting of Subaqueous Outfalls is feasible based on feedback received from local utilities in the State of Florida. The following permits might be required for the construction and operation of a Subaqueous Outfall in the City of Naples. Environmental Resource Permit from South Florida Water Management District (SFWMD) FDEP s NPDES permit FDEP s Bureau of Beaches and Coastal Systems permits as required based on final design of the proposed outfall Coordination and approval from U.S. Coast Guard City of Naples and/or Collier County approvals related to local ordinances, if any U.S Army Corps of Engineer s permit is not required by the City as the proposed length of the potential Subaqueous Outfall is less than 1,600 feet. The construction of Subaqueous Outfalls is highly challenging due to underwater work required. Work in boats, use of divers during construction complicates the construction of Subaqueous Outfalls. The degree of difficulty, time required, and, therefore, costs increase greatly with the amount of underwater work required. AECOM Technical Services Inc. Page 5

There is an ongoing regulatory concern that

FWRJ Alternatives for Beach Stormwater Outfalls: Preliminary Assessment for City of Naples Reshma Thummadi, Ronald Cavalieri, Andy Holland, and Gregg Strakaluse There is an ongoing regulatory concern that