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James W. Sewall


Sewall monitors five impaired urban streams

(Old Town, Maine-17 June 2009) The City of Bangor last week launched a two-year project to monitor the flow of five local streams defined as impaired by the Maine DEP-Penjajawoc Stream, Birch Stream, Arctic Brook, Capehart Brook and Shaw Brook. The project, part of Bangor's long-term initiative to improve water quality, is a critical first step to controlling stream contamination from stormwater runoff.

To assist the City, environmental engineers at James W. Sewall Company are now tracking both continuous instream flow (velocity and volume) and precipitation levels to determine the amount of stormwater runoff that impacts stream flow. Depth and precipitation monitors, permanently deployed in the five streams at ten data collection stations, record information at 15-minute intervals, which Sewall downloads and evaluates monthly. Once correlated with data on water quality, including such stressors as chloride, dissolved oxygen, stream temperature and nutrients, this information will provide the basis for modeling water quality and developing best management practices (BMPs) for water quality control.

Sewall Senior Environmental Scientist, Chester Bigelow, PWS, explains, "Runoff from paved roads, parking lots, sidewalks, and other impervious surfaces carries heat and pollutants into streams, such as road salt, nutrients from fertilizer, oil and grease, and organic material. In an urban environment these all work together to impact water chemistry and the health of the aquatic community. If we know how much flow is coming off of the land surface and can tie this information to water quality data, we can determine ways to reduce high stream flows, to restore and maintain the balance of the system, and to moderate the impact of pollutants on our streams. These practices will become part of Bangor's larger watershed management plan to improve water quality to Maine DEP standards over the long term."

According to Wendy Warren, City of Bangor Environmental Coordinator, "This project is a result of a huge amount of citizen support of the need for more water quality information. The data collected through this program will enable the City and facilities located in watersheds of impaired streams to develop more accurate models for making better decisions as to the sizing and efficiency of certain stormwater treatment systems. The anticipated result will be a win-win situation for facilities and the environment. Accurate modeling will assist facility managers in implementing the most cost-effective systems, and stormwater discharges will receive the treatment necessary to improve the water quality of receiving streams. We are very excited to receive the funding from the Maine DEP, Maine Municipal Bond Bank and American Recovery and Reinvestment Act (ARRA) that allows us to collect this information for all five of the City's impaired streams over the next two years."

Founded in 1880, Sewall provides integrated solutions in geospatial, engineering and natural resource consulting to government and industry. Sewall environmental engineers specialize in environmental assessment, wetland delineation and functional assessment, spill response and damage assessment, field collection and statistical analysis of chemical and biological data, and state and federal environmental permitting. For information, contact: Chester Bigelow, PWS, at 207 827-4456; Email: 



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