Enhancing Legacy | Engaging Process: Phytoremediation at Gas Works Park

Abstract

This thesis proposes the use of plants to remove hazardous wastes from soil and water, a process known as phytoremediation, as a promising alternative to traditional methods of toxics clean-up. This project focuses specifically on designing phytoremediation for Gas Works Park, a beloved city park and former manufactured gas plant, located in Seattle, Washington. Today the park, a 20 acre promontory jutting 400 feet into Lake Union with 1,900 feet of lake-front shoreline, maintains many of its original structures as well as water and soil pollution generated by 50 years of coal-gas manufacture. Since its completion in 1976, maintenance and monitoring crews at the park have struggled to contain the contamination that remains beneath a soil and clay cap. Forty years of intense recreational use and heavy seasonal rain storms have degraded the soil cap, exposing contamination, and requiring intermittent re-capping efforts. Physical evidence of toxic sediments leaching into the adjacent lake and seeping up to the surface of the park soils has been documented through continuous testing and monitoring activities. Residual pollutants on site have been respectively identified as toxic, carcinogenic, and mutagenic. These contaminants present a serious health risk for park users and the sensitive lacustrine environment surrounding the park. This project utilizes the burgeoning scientific field of phytoremediation to design strategies that remove and mitigate remaining contamination at the park and simultaneously create new user experiences. Experiences created by phytoremediation strategies are intended to educate visitors about the park’s history and engage them in the future of its clean-up. This thesis aims to further awareness of phytoremediation technology as a viable design tool and spark an honest dialogue about mitigating toxicity in public space.