The  Initial Objective:

“We are looking for a locally manufactured, perhaps fabricated from upcycled plastic design that is more mobile and portable in design that collects plastic in Proctor Creek (and beyond), which seeks to disrupt the existing designs. ” - Original Sponsor

Research: Prior Art

These are some of the plastics traps that were researched by the team to see what was currently used on Proctor Creek as well as what existed on the market. The only successful, small, and portable trap was the Seabin, but there were reports of it harming wildlife similar to what exists in Proctor Creek.

Research: Literature Review

(click on image to read document)



These are some reports that the team used in educating themselves on the current state of the watershed including ecological health, climate, legislation, community involvement, as well as previous and future projects.

Research: Interviews and Investigation 

Based on our interviews (and sponsor’s complete radio silence), the team concluded that our original sponsor, while important, could not be our primary stakeholder. Therefore, it would be more strategic for the team to collaborate closely with Chattahoochee Riverkeeper (CRK). To maintain inclusivity of all parties in our revised approach, we created the stakeholder map below.








Our object was rather vague, and thus the team settled on the following preliminary design criteria to better and more realistically achieve this goal.

1st Round of Prototyping

These were the 5 favorite initial conepts that the team came up with for CRK to review. But before we had them critiqued, the team shadowed CRK for the trap servicing process.


The feedback we recieved was:

1. Focus more on increasing capacity and minimize trash loss of the traps 
2. Smaller traps are also more difficult to service because of their limited access from the top.
3. There aren’t enough resources to effectively service additional traps.
4. CRK would like an easier way to access the larger traps – they currently climb over the top of them while servicing.
5. It’s a lot easier to sort the trash while still in the water instead of doing it on land.
6. Try to avoid large objects (logs, trees, etc.) from getting into the trap.
    

2nd Round of Prototyping

The feedback we recieved was:

Prevent Trash Loss / Trap Capcity 

1. Maximize height at back of trap
2. Sliding wall is first pick
3. Would like if part that slides out is able to sift trash
4. Hinges and slots are susceptible to getting jammed with trash
5. Need method to clean

Prevent Large Debris Jams

1. Logs sit much lower in the water than the trash
2. Trap needs to be self contained
3. Could funnel logs somewhere
4. Fin form factor suits log travel path
5. Large Log: 18” – 24” dia, 20 ft long
6. Branch: 2" -4” dia, 10 ft long

After the 2nd round feedback the team and Jordan from CRK agreed that prioritizing trash loss and capacity was more important and achievable in given other constraints.



I also did some initial mathematical models to define and quantify boundary conditions such as trap volume, persistant and periodic forces (drag, tree impact, trash) experienced by the trap.

Final Design Verification

Now we knew that CRK preferred the sliding mechanism for the walls. We proposed several methods of attaching the walls to the rails.

 

Both Jordan and Gillian liked the slid-in rail method (left) the most as it was the simplest to use and clean while still being secure.

We then updated our final design criteria as shown below. These would be used to verify the success of our project.




One of the ways in which we tested our final desing criteria was with FEA.  I ran some analyses in Solidworks to verify whether our final design would withstand the expected known environmental conditions.




The maximum simulated rail deformation was 9mm with a max stress of 200MPa. Both of these values are significantly below the point of failure.




The maximum simulated rail deformation was 1.8mm with a max stress of 20MPa. Both of these values are significantly below the point of failure.

To approximate the efficiency of our trap capture system we: 



Took measurements of the volume of trash that would overflow from the trap during storm surges.




This data is captured by USGS (resource mentioned earlier) during a week of heavy rains while we worked on the project. The three peak creek flow rates are shown and averaged together.




We found 24 occurrences over the last year where the flow rate of Proctor Creek went over 500ft³/s. This velocity correlates to sudden changes in creek height. In these 24 occurrences, there were 186 15 min periods where the flow rate was above this threshold.

Final Full Scale Design, Fabrication, and Installation

Additional Deliverables

(Fabrication Package and Educational Model)




I put together this fabrication package for our sponsor in case they wished to repair or recreate any of the deliverables. All Solidworks and STL files were also provided.





Here is a photo showing the set up of the educational model. It consists of a tank that with two sections that are seperated by an acrylic sheet. The bottom has a water pump that simulates th creek flow. On top of the acryllic sheet the 3d printed model floats and cut up sponges represent the trash.