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Contract #SD609AA reshaping and cleaning street swales and back lot ditches to route stormwater from the streets and yards to the canals and into the stormwater lakes/ponds for treatment. This project will convert the two borrow Pits known as Oak Lake and Lake 20 into detention facilities to hold rerouted stormwater as well as the reshaping and cleaning of the collector Canals A & B, and expanding the collector ditches along 80h Street and 80h Street to provide additional treatment. In September 1998, this project received approval for a 10 -year construction permit from DISTRICT under Permit #4-061-0163AGC-ERP for the drainage and detention pond construction. In addition to many drainage improvements to be completed by COUNTY, COUNTY proposed the construction of four laketpond systems for stormwater treatment. Two of these systems are described in this scope of work and include the construction of the Oak Lake System and the Lake 20 System with ponds A & B and associated wetlands. The Lake 20 system is proposed as a wet detention system, which will be constructed by enlarging two existing ponds to form a 10.7 -acre pond system. The system will contain approximately 60 -acre-feet of permanent pool volume with a corresponding residence time of 17 days. Approximately 535 acres of platted subdivision will be routed into the Lake 20 pond system. The Lake 20 system will discharge the treated stormwater through a control structure and pipe to Canal B. Oak Lake Area system is located south of Canal A and east of 961h Avenue. A control structure is proposed in Canal A, which serves the northern portion of the subdivision, to divert flow From [lie ditch into the Oak Lake area wet detention system. The Oak Lake wet detention system will consist of two interconnected stomhwater ponds which will be constructed by enlarging and interconnecting two existing borrow pits. The interconnected ponds will be approximately 16.5 acres in size and will contain 96 -acre-feet of permanent pool storage. The pond system will serve a drainage area of approximately 1,013 acres with a residence time of 14 days. The 1,013 -acre residential area served by the proposed pond will also receive pre-treatment in the roadside and back lot swales prior to trcahncni in the Oak Luke system. The back lot and roadside swates are designed with control structures to maximize Swale storage prior to discharge to Canal A. These swales will provide approximately 0.5 inches of runoff storage prior to discharge to the Oak Lake system and Canal A. In 1997 and 1998, COUNTY received two grant awards from DISTRICT's Local Government Cost -Share Program totaling $35,000. This money, in addition to fees collected from the Vero Lakes Estates M'STU, will be applied to the cost of constructing the ponds as well as reshaping the connecting ditches (see Budget). V. _ SCOPE OF WORK (A complete list of all tasks and their outputs): Task 1: Survey Project Site Description: COUNTY's engineering consultant will prepare a complete survey of the two lake system areas designated for development in this project. ExpecteResults: A complete survey of hake systems. Page 12 of 28