Control of oil spills in urban areas

The City of Toronto has experienced about 300 oil spills per year (Li 1997). Traditionally, the city recommends that businesses and industries practise pollution prevention and install on-site oil separators. Currently, the sizing criteria for these devices are not well defined and the draft code of practices for oil separators by the Canadian Petroleum Product Institute (1994) has not yet been approved by the Ministry of the Environment (Li 2000). Thus, the city is currently investigating the possibility of installing oil separators at spill prone sewer outfalls. The new application of oil separators at sewer outfalls requires that the devices be operable under high flow conditions and that their capacity should reflect the land use characteristics in the associated sewershed. This study has developed an innovative spill control device for the Humber Creek outfall and a Geographic Information System (GIS)-based analysis technique for urban oil spill management. First, a flow diversion structure was designed to capture the dry weather flow at the outfan and to transport the captured flow into an oil/water separator designed in accordance to the American Petroleum Institute's manual (1990). The designs of the flow diversion structure and the oil/water separator were evaluated by a physical model study using the National Water Research Institute's Hydraulics Laboratory at the Canada Centre for Inland Waters in Burlington, Ontario. Then, the GIS-based analysis technique was used to identify potential treatment options for spill-prone sewer outfall in the Town of Richmond Hill. It was found that (I) the spill event characteristics should be analyzed in order to develop design criteria for oil spill control systems; (2) the preliminary design of the oil spill control system at Humber Creek was different from the API's methodology; and (3) the physical model investigation confirmed the conveyance capacity of the diversion channel and the general behaviour of the tilted-plate separator. A database of oil spill records in the Greater Toronto Area from 1988 to 2000 were compiled and geo-referenced. By overlaying the spill characteristics and other GIS data layers, such as woodlots, wetlands and watercourses, spill prone areas were identified. In order to increase the accuracy of the analysis, the percentage of georeference oil spill locations should be increased.

Control of oil spills in urban areas

The City of Toronto has experienced about 300 oil spills per year (Li 1997). Traditionally, the city recommends that businesses and industries practise pollution prevention and install on-site oil separators. Currently, the sizing criteria for these devices are not well defined and the draft code of practices for oil separators by the Canadian Petroleum Product Institute (1994) has not yet been approved by the Ministry of the Environment (Li 2000). Thus, the city is currently investigating the possibility of installing oil separators at spill prone sewer outfalls. The new application of oil separators at sewer outfalls requires that the devices be operable under high flow conditions and that their capacity should reflect the land use characteristics in the associated sewershed. This study has developed an innovative spill control device for the Humber Creek outfall and a Geographic Information System (GIS)-based analysis technique for urban oil spill management. First, a flow diversion structure was designed to capture the dry weather flow at the outfan and to transport the captured flow into an oil/water separator designed in accordance to the American Petroleum Institute's manual (1990). The designs of the flow diversion structure and the oil/water separator were evaluated by a physical model study using the National Water Research Institute's Hydraulics Laboratory at the Canada Centre for Inland Waters in Burlington, Ontario. Then, the GIS-based analysis technique was used to identify potential treatment options for spill-prone sewer outfall in the Town of Richmond Hill. It was found that (I) the spill event characteristics should be analyzed in order to develop design criteria for oil spill control systems; (2) the preliminary design of the oil spill control system at Humber Creek was different from the API's methodology; and (3) the physical model investigation confirmed the conveyance capacity of the diversion channel and the general behaviour of the tilted-plate separator. A database of oil spill records in the Greater Toronto Area from 1988 to 2000 were compiled and geo-referenced. By overlaying the spill characteristics and other GIS data layers, such as woodlots, wetlands and watercourses, spill prone areas were identified. In order to increase the accuracy of the analysis, the percentage of georeference oil spill locations should be increased.

Modelling the fate of a larviciding chemical, methoprene, at drainage systems

With the recent occurance of mosquito-borne WEst Nile Virus (WNV) in Canada, the City of Toronto and the surrounding municipalities have undertaken the larviciding program to control mosquitoes during the summer months. The larviciding chemical, methoprene, can be incorporated in clay pellets or chalks which sink to the bottom of a catch basin sump. The main concern is whether or not the methorprene pellets or chalks will still be in a catch basin sump or to be flushed out during storm events. The objective of this thesis is to develop a water quality model, which is based on surface hydrology, mass balance and hydraulic characteristics of flushing at catch basin, in order to predict residual concentration of methoprene at catch basins and storm sewer outfalls. The findings of the research and all information from other contributing parties are expected to contribute to our understanding of the fate of methoprene at catch basins and storm sewer outfalls and improve the mosquito larviciding program in the Greater Toronto Area.

Modelling the fate of a larviciding chemical, methoprene, at drainage systems

With the recent occurance of mosquito-borne WEst Nile Virus (WNV) in Canada, the City of Toronto and the surrounding municipalities have undertaken the larviciding program to control mosquitoes during the summer months. The larviciding chemical, methoprene, can be incorporated in clay pellets or chalks which sink to the bottom of a catch basin sump. The main concern is whether or not the methorprene pellets or chalks will still be in a catch basin sump or to be flushed out during storm events. The objective of this thesis is to develop a water quality model, which is based on surface hydrology, mass balance and hydraulic characteristics of flushing at catch basin, in order to predict residual concentration of methoprene at catch basins and storm sewer outfalls. The findings of the research and all information from other contributing parties are expected to contribute to our understanding of the fate of methoprene at catch basins and storm sewer outfalls and improve the mosquito larviciding program in the Greater Toronto Area.

Cyclospora Cayetanensis Presence in the Environment—A Case Study in the Chicago Metropolitan Area

Cyclospora cayetanensis is an emerging foodborne protozoan pathogen. Similar to other gastrointestinal illnesses, cyclosporiasis causes prolonged diarrhea. Unlike Cryptosporidium, Cyclospora oocysts are not infective when they are shed by infected individuals. Oocysts mature in the environment for 7–10 days before sporulating. Little is known about how C. cayetanensis is transported in the environment and which factors inhibit or promote sporulation. Water and fresh produce, such as leafy greens and berries, are common sources of infection. Contact with soil has also been correlated with Cyclospora infection. In addition to acting as a vector to transport oocysts from the environment to the body, water and soil may be important reservoirs to not only allow C. cayetanensis to persist, but also transport the oocysts from one location to another. This study examined a snapshot of an urban area near Chicago where human waste sporadically enters the environment via combined sewer outfalls (CSO). A total of 61 samples were collected from three CSO discharge events. Most of the 21 positive samples were wildlife feces (n = 13), and a few were soil (n = 7). There was one positive water sample. PCR analysis of soil, water, and wildlife feces indicated the presence of C. cayetanensis in the environment, suggesting likely transport of oocysts by wildlife. Given the emerging threat of cyclosporiasis, additional studies are needed to confirm and expand this case study.

MINNESOTA NORTH SHORE AND DULUTH-SUPERIOR HARBOR SPILL RESPONSE STRATEGIES

ABSTRACT The Minnesota Lake Superior shoreline (Minnesota'S “North Shore”) is characterized by a rocky shoreline with stretches of sand, gravel and cobble as well as several stream and ditch inlets into Lake Superior. The risk of spills is from both land and water. The 150 plus mile stretch of shoreline has a very limited amount of response equipment or nearby responders. The Duluth-Superior Harbor is at the estuarine mouth of the St. Louis River and is divided by the Minnesota and Wisconsin border. The harbor includes sensitive shorelines and habitats, numerous stream, ditch and storm sewer outfalls, as well as an active shipping industry. Geographic Information System (GIS) is a great tool for conducting data analysis and planning. GIS allows users to analyze and visualize large volumes of data to make decisions quickly. While many spill response planners use GIS as a planning response tool, many responders do not have the training and equipment to make efficient use of the capabilities of GIS. This project uses GIS to gather and analyze available data and then put it into a useful “hardcopy” visual format for responders to use in the field. Maps produced from various GIS data sources outline the response strategies for sensitive areas to be protected; types and quantities of response equipment needed; access areas; and other important features. These “hardcopy” displays can be included in contingency plans. Larger laminated versions can be stored with response equipment caches. For response planners that are more familiar with GIS, the tool includes several useful features including “clickable” hyperlinks that connect to georeferenced oblique aerial photos of the Lake Superior shoreline. Also included are GIS data from U.S. EPA and NOAA, including sensitive environment, economic and cultural resources; potential spill sources; and response resources. Where available, sewer data for both sanitary and storm sewers is included, along with high resolution aerial photos; navigation charts; highway stream crossing data; and other habitat information. These various data sources are valuable tools for spill response planners to more accurately and effectively develop workable response strategies and also for use during an actual response to more effectively and efficiently direct responders and resources. This GIS product also incorporates an Access database which allows for easy report generation and information updating.

An Evaluation of the Impacts of Discharges from Surface Water Sewer Outfalls

A broad-based approach has been used to assess the impacts of discharges to rivers from 47 surface water severs, with the objective of determining whether such discharges are damaging to stream quality. In order to study as many sites as possible, sampling, laboratory and data analysis techniques were designed to be as simple and rapid as possible. This broad approach was deliberately chosen to contrast with other UK studies in which a small number of sites have been investigated in detail. Three parameters were studied, all of which could reflect the effects of intermittent pollution on stream quality during dry weather. These were the numbers and types of benthic nacroinvertebrates upstream and downstream of the outfalls, the concentrations of metals in algae upstream and downstream of the outfalls, and the concentrations of metals in sediments upstream and downstream of the outfalls. Information relating to the study catchments has been collected from local authorities and by observation at the time of sampling. This information includes catchment areas, land uses and receiving stream quality. Methods used for site selection, sampling, analysis and data interpretation are described. Results show that there is a small but significant fall in biological water quality downstreap of outfalls, but no consistent detectable impact on the concentrations of metals in sediments or algae. The biological effects are compared with the catchment characteristics to identify the factors governing the impact, and upstream water quality is found to be an important factor. Other factors influencing the impact are sewered catchment area and land use.