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The tasks which I mostly intensively focused this semester were the design, construction, and testing of a small scale SRSF to demonstrate for the EPA Expo, and the creation of an Excel mathematical model to generate a preliminary design for a sand drain based on user inputs.
For design of the small scale SRSF I completed many of the calculations required; such as head losses, flow rate requirements, and velocity requirements. As a group we were able to construct the frame to display the small scale filter and the filtration column itself. I focused my attention on the constant head tank, where I performed calculations to determine flow rate requirements, completed fabrication work, and performed hydraulic testing. I experimented with using an LFOM in the constant head tank to control the flow rate to the filter; however I found that the LFOM size calculated was not sufficient for the prototype because of head losses throughout the system. Consequently I needed to increase the flow rate, which I accomplished by increasing the height of the overflow pipe and switching the LFOM out for a simple orifice. Simply put, I used the "hole in a bucket" approach.
As a group, one of our goals for the semester was to design a sand drain for the low flow SRSF. Unfortunately much of our time was devoted to the design and construction of the EPA small scale filter; however we still did manage to complete some sand drain design work. As a group we did calculations by hand to obtain a design for a sand drain based on various user inputs. After completion of these calculations, I created a simple excel model which allows the user to manipulate various inputs; such as drain angle, pipe length from filter column, diameter of drain, and etc. Consequently, the model performs the calculations based on the inputs and determines whether or not the design is adequate. I specified the primary criteria for adequacy of the design by specifying a vertical height at which the sand drain must be above the ground; thus allow the operator to easily use a bag to remove the sand as it exits the drain.