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<ul class="nav nav-pills"> <li role="presentation" class="active"> [[Home]]</li> <li role="presentation">[[Library]]</li> <li role="presentation">[[Applications]]</li> <li role="presentation">[[Misc]]</li></ul> Below will not work, as there is no way to include the PHP files to send, plus Mediawiki does not allow most types of html within documents. <div class="control-group"> <label class="control-label" for="inputIcon">Email address</label> <div class="controls"> <div class="input-prepend"> <span class="add-on"><i class="icon-envelope"></i></span> <input class="span2" id="inputIcon" type="text"> </div> </div></div> the mid 1970s, attempts to control runoff flow rates from urban developments wereinitiated. By the late 1980s, water quality became an additional focus and in the late1990s, approaches to mitigate accelerated stream channel erosion were introduced.Lot level stormwater management approaches have been advocated in Ontario since1995 (OMMAH, 1995), but widespread application has yet to occur. Today, withimprovements in our understanding of watershed systems and the potential impactsurbanization can have on aquatic ecosystems, stormwater management addresses abroad suite of issues including fluvial geomorphology (stream channel formingprocesses), groundwater resources and the protection of aquatic and terrestrial habitats(Figure 1.2.1).
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CVC’s recent Credit River Water Management Strategy Update concludes thatcontinued use of what are currently considered “state of the art” stormwatermanagement practices will lead to continued degradation of the watershed, jeopardizingthe health of the Credit’s world class fishery and other valued environmental resources(CVC, 2007b). To protect the health of the Credit River watershed, the updated watermanagement strategy calls for an immediate shift to more proactive and innovativestormwater management systems that include low impact development practices.TRCA’s Rouge River Watershed Plan (TRCA, 2007c), Humber River Watershed Plan(TRCA, 2008a) and Don River Watershed Plan (TRCA, 2009a) reach similarconclusions about the inability of conventional stormwater management practices toprotect the health of rivers and the need for low impact development approaches. Inaddition, the Rouge River Watershed Plan concludes that widespread implementation ofLID practices in new and existing developments could increase the resiliency of thewatershed system to some anticipated impacts of climate change on baseflow andchannel erosion (TRCA, 2007d). Recent research (Aquafor Beech Ltd., 2006) has suggested that current practices tooffset the hydrologic effects of urbanization are insufficient to prevent increased channelerosion and deterioration of aquatic habitats. In many cases, even small incrementalchanges in watershed hydrology commensurate with an increase in impermeablesurfaces of 4%, can result in changes to stream channel characteristics and aquaticcommunities. To offset these impacts, an increased emphasis on maintaining naturalwater balance and replicating the predevelopment hydrologic cycle is required (AquaforBeech Ltd., 2006). Finally the 2003 OMOE Stormwater Management Planning and Design Manual, thoughreflective of current technology is rapidly becoming dated, since much of the material itreviewed dates from 1999. In the last five years, over 30 state-of-the-sciencestormwater management manuals and guidelines have been released in locations suchas Maryland, Washington State, British Columbia, Minnesota, Pennsylvania andOregon. The objective of maintaining predevelopment water balance, use of thetreatment train approach and application of low impact development practices are allbecoming common practice in these jurisdictions. Two recent documents, one prepared by the City of Toronto and the other prepared bythe Greater Vancouver Regional District summarize how the approach to stormwatermanagement needs to change.
Rainwater should be treated as a resource to nourish and enhance theCity’s environment. Management should begin where precipitation hitsthe ground according to the priority of source, conveyance, end-of-pipeand finally, stream restoration measures (City of Toronto, 2006).There is a need for a change in the philosophy of treating runoff fromone of stormwater management to rainwater management (GVRD,2005).
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In the mid 1970s, attempts to control runoff flow rates from urban developments were initiated. By the late 1980s, water quality became an additional focus and in the late 1990s, approaches to mitigate accelerated stream channel erosion were introduced. Lot level stormwater management approaches have been advocated in Ontario since 1995 (OMMAH, 1995), but widespread application has yet to occur. Today, with improvements in our understanding of watershed systems and the potential impacts urbanization can have on aquatic ecosystems, stormwater management addresses a broad suite of issues including fluvial geomorphology (stream channel forming processes), groundwater resources and the protection of aquatic and terrestrial habitats.
Municipalities, with the support of conservation authorities, review stormwater management facilities and plans designed to address this multitude of concerns. This has led to an increasing complexity in stormwater management planning and design including:
Municipalities, with the support of conservation authorities, review stormwater
management facilities and plans designed to address this multitude of concerns. This has led to an increasing complexity in stormwater management planning and design
including:
* increasingly complex stormwater management facilities and best management practices;
* increasingly complex stormwater management facilities and best management practices;
* increased emphasis on the treatment train approach and use of multiple types of controls to address environmental issues.
* increased emphasis on the treatment train approach and use of multiple types of controls to address environmental issues.
CVC and TRCA have been extensively involved in integrated watershed-wide
CVC and TRCA have been extensively involved in integrated watershed-wide environmental monitoring for many years. The results of this monitoring have shown that the environmental health of many watersheds continue to decline as urbanization increases. This environmental deterioration has taken place despite widespread compliance with provincial and conservation authority requirements for stormwater management planning and facility design. Conventional stormwater management, which focuses on controlling peak flow rate and the concentration of suspended solids, has failed to address the widespread and cumulative hydrologic modifications in watersheds that increase the volume of stormwater, increase the runoff rate, and cause excessive erosion and degradation of stream channels. Conventional stormwater management also fails to adequately treat other pollutants of concern, such as nutrients, pathogens and metals.
environmental monitoring for many years. The results of this monitoring have shown
that the environmental health of many watersheds continue to decline as urbanization
increases. This environmental deterioration has taken place despite widespread
compliance with provincial and conservation authority requirements for stormwater
management planning and facility design. Conventional stormwater management,
which focuses on controlling peak flow rate and the concentration of suspended solids,
has failed to address the widespread and cumulative hydrologic modifications in watersheds that increase the volume of stormwater, increase the runoff rate, and cause
excessive erosion and degradation of stream channels. Conventional stormwater
management also fails to adequately treat other pollutants of concern, such as
nutrients, pathogens and metals.1
This is why CVC and TRCA commissioned the development of the 2010 stormwater management guide, to provide guidance on the kind of cutting edge practices that are needed to protect the health of the CVC and TRCA watersheds. The LID SWM Guide draws on published research, literature and local studies to provide planning and design guidance that reflects regional policies, practices and climate. It provides information
This is why CVC and TRCA commissioned the development of a stormwater
management guide to provide guidance on the kind of cutting edge practices that are
needed to protect the health of the CVC and TRCA watersheds. The LID SWM Guide
draws on published research, literature and local studies to provide planning and design
guidance that reflects regional policies, practices and climate. It provides information
and guidance on the following:
and guidance on the following:
* the kinds of environmental and performance monitoring that should be carried out.
* the kinds of environmental and performance monitoring that should be carried out.
Acknowledging that it will not always be possible to maintain the predevelopment water
Acknowledging that it will not always be possible to maintain the predevelopment water budget of a site, predicted increases in runoff from land development that cannot be
budget of a site, predicted increases in runoff from land development that cannot be
mitigated through stormwater infiltration practices should be minimized through practices that either evapotranspire (e.g., green roofs, bioretention), or harvest runoff for
mitigated through stormwater infiltration practices should be minimized through
practices that either evapotranspire (e.g., green roofs, bioretention), or harvest runoff for
non-potable uses (i.e., rainwater harvesting). In areas where development has already
non-potable uses (i.e., rainwater harvesting). In areas where development has already
taken place, LID can be used as a retrofit practice to reduce runoff volumes, pollutant
taken place, LID can be used as a retrofit practice to reduce runoff volumes, pollutant