GSI and Permeable Asphalt in our Site

The two main methods that we plan to use for managing stormwater in our site are:

• GSI
• Permeable Asphalt

The design of these two components was based on terrain data that we got from Google Earth, which accounted for a difference of 28 feet between left and right extrema (Figure 1, 2) of the parking lot. We intend to create a flow of water from left to right of the parking lot, which will be facilitated by these two methods. 

           

   Figure 1 Left Corner, elevation 70 feet                          Figure 2 Right corner, elevation 42 feet

GSI

This method will account for the majority of the rainwater in our site. Curb bump outs will be placed on the right part of parking lot, in which most of the water absorption will happen. Curb cuts will be placed every 12.75 - 13.00 m (Figure 3), which will allow water absorption by the soil. The total area covered by these methods , in the right part of the parking lot is around 1560 m^2 . Furthermore, the vegetation that will be used in this part of the site (Figure 4, 5,6) have moderate absorption rates, are native to US, and their dimensions match with our overall design. 

Figure 3. Curb Bump Out

Figure 4. Blackeyed Susan

Figure 5. Fountain Grass

                                       

                                                     

Figure 6. New England Aster

Table 1. Characteristics of the species used in the site

Permeable Asphalt

In order to overcome the problem of the plateau located near the railway supports, we plan to use permeable asphalt in certain areas of the parking lot. This will increase water absorption by the asphalt in the respective areas, by avoiding the creation of puddles of water during rainstorms, which not only hinder water flow, but also slowly damage the asphalt.

• How will Permeable Asphalt work in our site?

The joint material allows for water to seep in between the concrete pavement, and into either the sub base or the under drain. Theoretically, the under drain will retrieve water and deliver it to a source of water. The down pour that occurs within the parking lot will theoretically be delivered directly into Schuylkill River, preventing potential erosion and sedimentation.

[1] “Landscape Manual 2014” |Philadelphia Water Department, N.p. Web  2014, n.d. Web. 17 May 2017