In-Pipe Stormwater Treatment Unit Best Management Practice (I-STUB)

Description (excerpt)

This application claims priority to U.S. Provisional Application No. 63/722,196, filed 19 Nov. 2024, titled “In-Pipe Stormwater Treatment Unit Best Management Practice (I-STUB)” (Navy Case #212422). FEDERALLY-SPONSORED RESEARCH AND DEVELOPMENT The United States Government has ownership rights in the invention claimed herein. Licensing and technical inquiries may be directed to the Office of Research and Technical Applications, Naval Information Warfare Center Pacific, Code 72110, San Diego, CA, 92152; voice (619) 553-5118; NIWC_Pacific_T2@us.navy.mil. Reference Navy Case Number 212422. BACKGROUND OF THE INVENTION Urbanization and industrial activities have led to increased impervious surfaces, such as roads, rooftops, and parking lots, which significantly contribute to stormwater runoff. This runoff often carries various pollutants, including sediments, heavy metals, oils, and organic matter, from these surfaces into the stormwater drainage systems. Traditional stormwater management systems are primarily designed for flood control and often lack efficient mechanisms for pollutant removal. Consequently, untreated stormwater runoff can severely impact aquatic ecosystems, water quality, and public health. The need for effective stormwater management is underscored by stringent environmental regulations and growing awareness of water pollution issues. Current solutions, such as retention ponds, bioretention cells, and end-of-pipe treatment technologies, have limitations regarding space requirements, maintenance, and effectiveness. These traditional methods can be costly and challenging to retrofit in densely populated urban areas. There is a need for an improved stormwater filter. SUMMARY Described herein is a filter for removing contaminants from stormwater comprising a plurality of individual treatment units (ITUs) and a plurality of rigid linkage arms. Each ITU includes a perforated filter body having an inlet end and an outlet end. Each ITU further includes a filter bag deployed within the perforated body and connected to the inlet end such that all stormwater entering the inlet end is channeled into the filter bag. Each rigid linkage arm is configured to connect the inlet end of one ITU to the outlet end of a different ITU so as to form a chain of ITUs and rigid linkage arms. Each linkage arm is configured to connect two given ITUs so as to limit side-to-side movement of the given ITUs with respect to each other. An embodiment of a filter for removing contaminants from stormwater in a drainage system is also described herein as comprising a perforated body, a filter bag, a first cap, a capture cone, and a linkage arm. The perforated body has an inlet end and an outlet end, each of which has a receiving post. The first cap comprises an open end and an attachment end. The first cap is configured such that when the attachment end is attached to the perforated body's inlet end the filter bag is secured to the perforated body such that stormwater entering the inlet end is routed into the filter bag. The capture cone is configured to attach to the open end of the first cap. The capture cone is made of a flexible material that is able to conform to bottom contours of the drainage system. The linkage arm is rigid and configured to attach onto either of the receiving posts such that movement of the perforated body with respect to the linkage arm perpendicular to a long axis of the linkage arm is minimal. Also disclosed herein is a method for removing contaminants from stormwater in a drainage system comprising the following steps. One step provides for positioning a first of a plurality of ITUs along a bottom surface of the drainage system. Each ITU of the plurality of ITUs includes a perforated filter body having an inlet end and an outlet end. Each ITU further includes a filter bag deployed within the perforated body and connected to the inlet end such that all stormwater entering the inlet end is channeled into the filter bag. Another step provides for attaching a first rigid linkage arm to the first ITU. The first rigid linkage arm is configured to attach to the first ITU such that movement of the first ITU's perforated body with respect to the first rigid linkage arm perpendicular to a long axis of the first rigid linkage arm is minimal. Another step provides for pushing the first ITU and the first rigid linkage arm into the drainage system. Another step provides for attaching the plurality of ITUs via a plurality of rigid linkage arms in a same manner as the first rigid linkage arm is attached to the first ITU so as to create a chain of ITUs and rigid linkage arms. Another step provides for pushing the chain of ITUs and rigid linkage arms into the drainage system one ITU or rigid linkage arm at a time as each ITU or rigid linkage arm is attached to the chain of ITUs and rigid linkage arms. Another step provides for securing an inlet end of the chain of ITUs and rigid linkage arms to an inlet of the drainage system. Another step provides for pulling the chain of ITUs and rigid linkage arms out of the inlet of the drainage system after the stormwater has passed through the chain of ITUs and rigid linkage arms.