Addressing Pollutants in Stormwater Runoff

Anreeta Saseetharran enjoys learning about and exploring science and engineering. She is involved in her school’s robotics team, as well as other STEM related activities. In her free time, she also likes to create, craft, and read. Alon Lahav is involved in the robotics team and enjoys other STEM-related activities; he also sees his future in STEM. He is interested in coding and 3-D design as well as sports, including basketball. Aayush Patkar enjoys playing many sports as well as producing music. Additionally, his passion in art is what has inspired him to pursue a career in Product Design. Along with STEM-related activities in school, Aayush is also involved in FBLA. All three of them have taken the Introduction to Engineering Design and Principles of Engineering courses at Fremont High School in Sunnyvale, California.

Hello, everyone! Recently, the three of us had the chance to participate in the 2017 PLTW Engineering Design Competition, a national contest sponsored by Chevron that challenged us to create or improve upon our community's infrastructure. With this prompt in mind, we set about thinking of different problems we noticed, such as traffic congestion and crumbling roads.

The issue of pollutants entering our storm drains ended up on our list. Here in Sunnyvale, the water collected by the storm drains flows directly into the local creeks and the San Francisco Bay. The systems are designed to control flooding, and the stormwater is not actually treated. This means that oil, grease, coolants, heavy metals, fertilizers, pesticides, bacteria, soil, dirt, soaps, spilled chemicals, and anything else on the ground will end up in the creek or bay. As a result, nearby water ecosystems are left vulnerable. Polluted stormwater runoff harms fish and wildlife, destroys vegetation and animal habitats, pollutes water supplies, and ruins recreational areas. Through further research, we saw that many other cities, even those in different states, have this same flaw with their infrastructure.

Previously, we had noticed lettering above storm drains stating things like “Drains to Bay,” but we had never really considered the impacts of this too closely. Our actions, including washing our cars, using pesticides, and watering our lawns, leads to runoff and negatively impacts the environment. We chose to address this problem since it is especially relevant to us in the Bay Area and because of the resulting damage to water ecosystems. A successful solution could prevent the pollution of streams and creeks all over the country.

Applying the design process we were introduced to in our engineering classes, we were able to organize our response to this problem. We followed the steps of the process, from defining the problem to generating concepts; to developing a solution and constructing and testing a prototype; to evaluating a solution and deciding what the next steps for our design would be.

With the help of a decision matrix to decide which concept to pursue, we ultimately were able to design and prototype a storm drain filter that would be placed underneath storm drains and prevent pollutants from passing through. We researched materials that we wanted our design to use but made substitutions for materials that were harder to acquire in our physical prototype.

We were actually able to test our prototype filter with stormwater we collected as well as a dirty sample of water we prepared. We used UV-Visible Spectrophotometry, a technique some of us had used in science classes before, to ensure our filter reduced the cloudiness of the water, as well as pH tests to determine our filter’s effects on polluted samples. We designed and performed a lab experiment, fortunate to have access to our school’s science equipment. It was super cool to be able to apply knowledge from our science classes in testing our design.

In documenting the data from experiment, we discovered that our storm drain filter prototype was close to meeting our goals! In evaluating our solution, we decided that the next step would be to construct a complete prototype before again testing our storm drain filter’s effects on turbidity, pH, and chemical content of water in a lab environment. The design process is iterative, after all, and our initial testing made us believe this idea can potentially be implemented in the future.

It was amazing to be able to compete against students from all over the nation. We didn’t know what problems other teams would address when we started, especially those living in very different regions, and we are definitely interested in hearing about the improvements they proposed. We are really proud that we were able to place second with our design. We are very grateful to Project Lead The Way and Chevron for providing us with this opportunity.

PLTW’s blog is intended to serve as a forum for ideas and perspectives from across our network. The opinions expressed are those of each guest author.