The Detention Pond 9-25-2014
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While walking along S. Zinnia Ct. and S. Youngfield Ct. you may have noticed some drainage fixtures being placed. These are forming a "detention pond".
It's important to note that this feature of the site is funded directly by Jeffco Public Schools and not the GOCO grant, PTA or public donations, so it is not technically part of the Field of Dreams. |
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The fixtures have some interesting characteristics. The fixture for water inlet, above, and the outlet below, are on similar levels. They are not forming a reservoir with a spillway at the high water mark. Also of note, the inlet to the pond is large and the outlet from the pond is smaller. This took some research and it might may well become a science project or two for the students at Foothills Elementary.
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A Google search will quickly get answers as well as the comparison between detention ponds and retention ponds. A retention pond retains water and typically always has water in it; the outlet or spillway determines the capacity. A dam forms a retention "pond". In comparison, a detention pond is engineered to slow water down so as to mitigate the flooding effect of water draining from a large area.
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So on closer inspection, the observer will see that the pond is wide and has walls much higher than the outlet fixture. This allows the pond to hold a rush of water that is more than the outlet can handle. And this is how the detention pond slows down the flow of water in extreme conditions.
"The detention pond is not intended to hold water on a permanent basis and will appear to be a grassed depression most of the time. During very heavy rains water diverted into the pond will be released in a controlled manner into the city’s storm water system." - Jeffco
This particular detention pond releases water from a bit higher than the bottom of the pond so it has an added benefit of allowing the drainage water to settle out some in the pond. The water moving out is clearer than the water entering the pond. Over time, water left in the pond below the outlet soaks into the ground or evaporates.
The engineering for the pond must be very interesting in calculating the amount of water that can collect on the entire playground and how large the pond and outlet must be to achieve the desired effect. And of course the 100 year conditions must be taken into consideration exactly like the calculations that are going on all over Colorado as the result of our recent massive flooding. Imagine a detention pond that is acres big! In fact when a river leaves its banks, the effect is like a detention pond. Sounds like a science project.
"The detention pond is not intended to hold water on a permanent basis and will appear to be a grassed depression most of the time. During very heavy rains water diverted into the pond will be released in a controlled manner into the city’s storm water system." - Jeffco
This particular detention pond releases water from a bit higher than the bottom of the pond so it has an added benefit of allowing the drainage water to settle out some in the pond. The water moving out is clearer than the water entering the pond. Over time, water left in the pond below the outlet soaks into the ground or evaporates.
The engineering for the pond must be very interesting in calculating the amount of water that can collect on the entire playground and how large the pond and outlet must be to achieve the desired effect. And of course the 100 year conditions must be taken into consideration exactly like the calculations that are going on all over Colorado as the result of our recent massive flooding. Imagine a detention pond that is acres big! In fact when a river leaves its banks, the effect is like a detention pond. Sounds like a science project.