Agenda - 08-23-1993 - C 2 and C 3 attch

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Provisions for Draining the Pond A means of completely draining the pond must be provided (except in the instance of an excavated pond). This can be accomplished by extending a pipe from the riser into the basin with a valve or gate on the end (one designed expressly for the purpose of use in a pond) or a 1�` separate pipe through the dam with a valve on the downstream end (buried in the embankment to prevent freezing and vandalism) to drain the pond. The device should be sized to drain the pond within two to five days. Aesthetics Care should be taken in the design and construction so that the pond fits in with the surrounding development and environment. Debris should be burned (where possible) or otherwise properly disposed of instead of left in a pile. On industrial, institutional, commercial or multifamily projects other configurations of impoundments may be more desirable to fit in with the surroundings. Stabilization and landscaping of the finished pond should be planned with consideration given to the appropriateness of other uses. Sediment Storage, Removal, and Disposal It is highly recommended to.provide a sediment storage area in the forebay of the pond. The goal is to concentrate the majority of the sediment in a confined area so that it can be eventually removed. The intent is to make sediment removal more economical by confining most of the sediment in an area that is within reach of a rubber-tired backhoe sitting on the shore. This will hopefully eliminate the necessity and expense of having to drain the pond for excavation or bring in a larger tracked backhoe or dragline to remove sediment. A sediment storage area can be provided by constructing a baffle across the basin to enhance sedimentation. The recommended method is to use a rip-rap gabion (wire baskets filled with stone) to build the baffle. This is a long lasting method durable enough to withstand the impact of a backhoe excavating the accumulated sediment behind it. Sediment Disposal Area A disposal area must be provided within the project upstream of the pond for convenience and economy. This area must be designated on the site plan. Accumulated sediment must be removed when half the depth is taken up in the sediment forebay. Access Access for maintenance and periodic sediment removal must be provided. Access connected to a public right-of-way must be designated on the subdivision or site plan . The access must be cleared at least 30 feet wide during construction of the pond. A stone travelway at least 12 feet wide and 4 inches thick must be provided down the center of the access. DRAFT 9 June 1993