Workshop III : Site Engineering and Water Management, Fall 2019
University of Pennsylvania
Program : Rain Garden
Site Location : Richards/Goddard Plaza, Philadelphia, PA
Gross Area : 0.25 acre
Main plaza (50’x45’) and entrance plaza (90’x30’) are both paved with asphalt mixed with gravel, and the stair connecting these two plazas are made of bricks. The area surrounding the main plaza is a slope covered with grass. Surface runoff from the surrounding area of the main plaza flows along the slope and gets collected in the yard inlet(YI No.1) and the catch basin(CB No.3). Surface runoff from the entrance plaza and Hamilton Walk flows along the Hamilton Walk into the catch basin(CB No.1, 2) and trench drain(TD No.1). In the current situation, catch basins and trench drain can only manage surface runoff into some level. Due to the size of the inlets and impervious paving of the plaza, undesirable puddles could be created in situations with heavy storms.
In the proposal, the entrance plaza where people normally walk through is covered with porous paving which can infiltrate water as it falls onto the ground without creating a puddle. Also, slot drains are installed on the border of the plaza and Hamilton Walk to collect stagnant water along the border line, and in front of the stairs to prevent water flowing down the steps. Main plaza where people can stay and rest is covered with gravel that can infiltrate water, and has two rain gardens. Rain gardens can collect and retain water from the surrounding slope using plants and soil media. Collected water will slowly flow into the yard inlet on the bottom of the rain garden and move to the underground pipe. Using the landscape system to manage the surface runoff is beneficial in this area because creating a rain garden by utilizing the existing slope can maximize the use of current topography and manage surface runoff more easily. Moreover, creating a microclimate in this currently barely-used site can benefit the ecosystem as well.