I have divided the park into four sections. I have also done calculations to know the amount of stormwater runoff produced by each section in a one inch rain event. This tells me approximately how large a storage reservoir might need to be. Calculations were made using pervious and impervious CN values and % coverage. I do not know the surface types of the park because it is yet to be designed so I used 40% impervious surface with a CN value of 98. The remaining 60% was considered greenroof with a CN value of 84. The diagram outlining the beam walls and available areas for substantial tree roots can also serve as suitable areas for under deck water storage. Later in the design process, I can determine how much runoff is available from runoff. I can also determine possible use quantities for that water according to irrigation needs for lawns or gardens.
Section I
Using this method, the first section (between Church and Broadway) is 3.56 acres and produces 3,950 cubic feet of runoff in a one inch rain event. Water is collected on the plan north end of the park in a natural streambed surrounded by grasses. The water runs to an underwater storage reservoir for possible use in irrigation. A splash pad is located nearby and could possibly use this water with the addition of a UV filter. Runoff from the skate park is also channeled into a streambed.
Section II
Section II is 2.95 acres in size and produces 3,273 cubic feet of runoff. Section II features a similar streambed planted with grasses to channel water through the site to a storage reservoir below the deck. Water is also channeled in the east plaza, and could make for a nice design element. One issue with a ephemeral stream running the length of the site is pedestrian crossing. Since it will be dry a majority of the time, crossings could be a step over a rock. Bridges would provide crossing when the stream is wet.
Section III
Section III is the largest section at 4.47 acres and creates 4960 cubic feet of runoff. Section III was designed in this version as a park for passive recreation and reflection. The structure below allows for substantial tree planting on the North and South ends, blocking the city traffic. The East end is planted as a cedar glade, which is perfect for shallow soils. Cedar glades are common in the Central Basin of Tennessee. The West end is planted as a meadow. A streambed provides natural division of the meadow and the glade. Both feature a central gathering space at the conversion of the pedestrian paths. The stream culminates with a below grade storage reservoir. Since the plantings in this section will require little water, the topography could allow for the irrigation of the lawns with Section II to the East. There are obvious issues with this design. Blocking out the city also screens the view into the park, but I wanted to put it down on paper anyways as I think it would be a special space in the city. It could be closed at night at each plaza to prevent any funny business after hours.
Section IV
Section IV is 3.36 acres in size and produces 3,728 cubic feet of runoff. Streets on the North and South sides of the park dictate the park edges (thanks again Erin). This design keeps the roads. Unlike the other decks, this deck is 75% on grade with its surrounding topography. This means that pedestrians have more entrance points into the park. Water is collected in a similar method as the other decks. The streambed is on the North end of the deck. This section is programmed for active recreation. The field of the West end of the deck has the opportunity to be leveled, making it a suitable surface for ball fields. The West section will be sloped and is suitable for a dog park.
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