Background Report - Town of Georgina

Sutton Secondary Plan Review Study May 2008
Existing Environmental Conditions and Opportunities/Constraints Analysis
Project No. TA4468
The above constraint criteria have been combined to form a proposed approximate development limit, as
shown on Figure 4 (Natural Heritage System). Mapping of certain development setback criteria such as
floodline (plus 15 m setback), the 100-year meander belt width (plus 15 m setback) and stable top of bank
(plus 15 m setback) were not part of the mandate of this study. Depending on the results of a floodplain
analysis, fluvial geomorphological assessment of the 100-year meander belt width and a geotechnical
assessment of the stable top of bank (where applicable), additional setbacks may be required along the
Black River corridor and other watercourses. The refinement of the final limits of development should be
established through an Environmental Impact Study (EIS), at the draft plan of subdivision stage.
A proposed Natural Heritage System for the Sutton Secondary Plan Review Study is presented in
Figure 4.
In order to address the protection, enhancement and restoration of the Black River (Subcatchments 15 and
16), the following best management practices should be incorporated into future developments within the
Sutton Secondary Plan area:
• Enhanced (former Level 1) quality treatment for stormwater runoff;
• Attenuation of post-development stormwater runoff to pre-development levels for design
storms up to and including the 100 year storm event;
• 24 hr. detention of runoff from 25 mm storm event;
• Maintenance of the pre-development pattern and volume of groundwater recharge/discharge
(water balance) to maintain wetland hydrology, stream baseflow and stream thermal regime;
• Removal of barriers to fish migration;
• Rehabilitation of disturbed stream banks with native plantings (wetland, bottomland) and
other bio-engineering measures to provide shading and habitat creation;
• Storm pond outlets should be located (where feasible) in areas of existing disturbance where
rehabilitation is recommended;
• Cooling measures should be incorporated in storm pond outlet design (e.g. buried stone
gallery) to offset thermal loading within the ponds and mimic groundwater seepage zones;
• Promote environmental stewardship/education. Encourage wise use or avoidance of
commercial lawn chemicals for landscaped areas. Limit use of road salt/sand in winter;
• Naturalize buffer/setbacks to environmental protection areas with native species indicative of
the watershed and local setting. Stabilize erosion prone stream banks with thicket forming
shrubs;
• Remove invasive plant species from forest edges and wetlands; and,
LGL Limited environmental research associates Page 16