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Line 258: − + + − The forebay should be separated from the main pond by an earthen berm, which should be constructed as a small dam since the downstream portion of the pond remains dry. A weir at the top of the berm will convey flows to the downstream section during storm events. To facilitate maintenance, a pipe with an upstream valve should be installed within the berm to allow the forebay to be drawn down for cleaning. The berm should also be planted with emergent vegetation to enhance filtration of water as it passes over.
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===Forebay===
===Forebay===
A sediment forebay facilitates maintenance and improves pollutant removal by trapping larger particles near the inlet of the pond. The forebay should include a deep permanent pool (> 1 metre) to minimize the potential for scour and re-suspension. The forebay sizing depends on the inlet configuration, and several methods for sizing are provided in Section 4.6.2.
[[File:Dry pond forebay.png|300px|thumb|Dry pond forebay, adapted from MOE (2003)]]
A sediment forebay facilitates maintenance and improves pollutant removal by trapping larger particles near the inlet of the pond. The forebay should be separated from the main pond by an earthen berm, which should be constructed as a small dam since the downstream portion of the pond remains dry. A weir at the top of the berm will convey flows to the downstream section during storm events. To facilitate maintenance, a pipe with an upstream valve should be installed within the berm to allow the forebay to be drawn down for cleaning. The berm should be planted with emergent vegetation to enhance filtration of water as it passes over.
===Inlet===
===Inlet===
The number of discharge points into the pond should be kept to a minimum. To reduce erosion risk, the use of environmental stone or interlocking blocks with large openings that support vegetative growth is recommended at the inlet. A flow deflector or energy dissipation blocks may also be installed to limit scour and prevent the resuspension of previously settled pollutants from the pond bottom.
The number of discharge points into the pond should be kept to a minimum. To reduce erosion risk, the use of environmental stone or interlocking blocks with large openings that support vegetative growth is recommended at the inlet. A flow deflector or energy dissipation blocks may also be installed to limit scour and prevent the resuspension of previously settled pollutants from the pond bottom.