Petroleum Terminal

Providence, Rhode Island

Roux Associates, Inc. designed, installed and continues to monitor a constructed wetland at a major petroleum company's active petroleum terminal (and former refinery) in Providence, Rhode Island. The system was installed as part of our extensive on-going work at the terminal, which has included pilot and full scale implementation of numerous innovative and conventional remedial approaches.

The 7,000 gallon-per-day (gpd) constructed wetlands treatment project was designed to evaluate the removal of benzene, toluene, ethylbenzene and xylenes (BTEX) from groundwater discharging to surface water at the site. The system's high aesthetic, low visual impact appeal was ideal for its golf course setting. The system was designed to passively intercept and treat the contaminated groundwater in-situ. Several innovative features were designed into the system to enhance the aerobic microbial degradation of the target constituents, minimize odor and aesthetic impacts and eliminate exposure concerns to recreational users and indigenous wildlife populations. Parallel flow cells were incorporated into the design to assess the biodegradation/biotransformation processes for multiple wetland plant species.

The system was constructed in the spring of 1996, and a growth and maturation plan was developed in order to evaluate the system performance. Nutrient addition and re-planting modifications have been implemented to enhance growth. The results of performance sampling indicate BTEX removals typically exceeded 83 percent for the period of May 1998 through April 1999 and have consistently exceeded 98 percent from May 1999 to present day.