Page 433 - The Engineering Guide to LEED-New Construction Sustainable Construction for Engineers

Low-Impact Development and Stormwater Issues 393

Exercises
1. You are going to pave a parking lot on 0.5 acre of land. You are required to maintain a minimum
of 10 percent of the area as landscaped or green space. You decide to incorporate bioretention cells
into three landscape areas in the parking lot.
A. Sketch an example parking lot and show the stormwater mass balances around the parking
lot.
B. Sketch one of the bioretention cells and make a box model around it showing the overall
water mass balance. Define each variable and incorporate them into Eqs. (10.2.3) and
(10.2.4). Assume that there is no overflow pipe in the bioretention cell.
2. Most bioretention cells have overflow pipes that are in the top of the gravel layer or somewhere
else in the interior. This changes the amount of the storage volume filled until there is flow out from
the cell. Using the site in Exercise 1, modify the equations to incorporate this additional outflow
option and show a sketch of the new box model.

3. You are going to develop a 1-acre site with a building, parking areas, and a drive. You opt to
use a detention pond for the site.
A. Sketch the site and depict the stormwater flows on the plan.
B. Sketch the detention pond and make a box model around it showing the overall water mass
balance. Define each variable and incorporate them into Eqs. (10.2.3) and (10.2.4).
4. You are going to develop a 1-acre site with a building, parking areas, and a drive. You opt to
use a retention pond for the site.
A. Sketch the site and depict the stormwater flows on the plan.
B. Sketch the retention pond and make a box model around it showing the overall water mass
balance. Define each variable and incorporate them into Eqs. (10.2.3) and (10.2.4).
5. You are going to develop a 1-acre site with a building, parking areas, and a drive. You opt to
use swales which will connect to an existing stormwater pipe in the street for drainage.
A. Sketch the site and depict the stormwater flows on the plan.
B. Sketch one of the swales and make a box model around it showing the overall water mass
balance. Define each variable and incorporate them into Eqs. (10.2.3) and (10.2.4).

6. You are going to develop a 1-acre site with a building, parking areas, and a drive. You opt to
use a small manmade wetland for the site.
A. Sketch the site and depict the stormwater flows on the plan.
B. Sketch the wetland and make a box model around it showing the overall water mass
balance. Define each variable and incorporate them into Eqs. (10.2.3) and (10.2.4).
7. You are asked about phosphorus removal in the wetland from Exercise 6. The reeds in the
wetland are known to uptake phosphorus. Sketch the wetland and make a box model around it
showing the overall phosphorus mass balance. Assume that the concentration of phosphorus in
the water in the wetland is completely mixed. Define each variable and incorporate them into
Eqs. (10.2.11) and (10.2.12).
8. You are asked about phosphorus removal in the bioretention cell from Exercise 2. The organic
layer in the cell has been shown to uptake phosphorus. Sketch the bioretention cell with the various
layers and make a box model around and within it showing the overall phosphorus mass balance.
Assume that the concentration of phosphorus in the water in each layer is completely mixed.
Define each variable and incorporate them into Eqs. (10.2.11) and (10.2.12). (You will probably
need a series of mass balance equations.)