Environmental Impact Assessment: 138 St Giles St

Environmental Impact Assessment #138 St Giles St (PID 004-564-405)

Purpose

This report is in response to a request by the Town of View Royal for an Environmental Assessment of impacts resulting from a proposed subdivision of a property located at 138 St Giles St as well as an encroachment into the 15m leavestrip along Portage Inlet. The encroachment has to do with stormwater from the proposed development as a small underground culvert will be required to move stormwater outside of the 15m leave strip into the ocean. The conduit will be for localized stormwater off the roof and impermeable surface areas resulting from the development. The development will also result in the removal of an existing structure that is currently being used as a dry dock shop and residence. Further to the above, encroachments into the 15m leavestrip is also to accommodate a sewer connection to an existing Right of Way/ROW (1.5m encroachment into leavestrip). Please refer to Attachment I for an overview map of the property, Attachment II for locations of the proposed encroachments and Attachment III for typical site photographs.

Background

At the request of Whitney Garside of 120 Sims Road in Victoria, BC, Cascadia Biological Services was retained to conduct an environmental impact assessment of proposed works associated with a two lot subdivision and the construction of two single family dwelling and related encroachments into a 15m leavestrip adjacent to Portage Inlet in the Town of View Royal. The proposed works identified above and their locations on the subject property were assessed during a field visit by Mr. Thomas Roy, R.P. Bio. of Cascadia Biological Services on August 29th and 30th of 2013. The purpose of the site visit was to examine the physical and biological attributes of the leavestrip, review proposed works, and to discuss how best to minimize or offset the environmental impacts resulting from the proposed works. Prior to the field visit, an overview search of existing environmentally significant areas was conducted.

Environmental Assessment Findings

1. Land Use – The riparian zone along the foreshore of Portage Inlet has been utilized for residential purposes for many years. Most of the native vegetation in and around the subject property has been replaced by lawns and ornamental gardens comprised primarily of introduced species.
2. Subject Property – The leavestrip within the subject property measures approximately 450 m² and has been mostly disturbed (>90%) as a result of past tree removal, ROW construction and services (sewer pipe adjacent to the property) as well as refuse from a historical dry dock facility. Existing vegetation within the previously disturbed areas consist primarily of introduced grasses and various weeds.
3. Rare Plants/Wildlife/Ecosystems – From our assessment, there are no environmentally significant polygons/attributes including rocky outcrops, wildlife trees, wildlife dens, rare plants/wildlife within the 15m leavestrip of the subject property.
4. Marine environment – Environmental sensitivities adjacent to the proposed home sites include some patchy eel grass beds within the muddy substrate extending out from the marine tidal line to the end of the assessment area (10m study area from the marine environment interface and line drawn perpendicular to the interface projected out into the ocean). An existing dock and dry dock building and associated pilings are currently the only structures affecting this area.
5. Riparian Areas Regulations (RAR) Waterbodies – There are no fresh water watercourse within 30m of the existing property lines. A RAR report is therefore not required.

Options and Recommendations

It is in my opinion that the proposed subdivision of 138 St Giles St. will not negatively impact the environment and/or the 15m leavestrip if the following recommendations are adhered to:

1. Works within the 15m leavestrip will be monitored by a Registered Professional Biologist (R.P. Bio.) during excavation and back filling of proposed works within the 15m leavestrip as well as the demolition of the existing dry dock structure and housing rental. Any contraventions will be forwarded by the on-site biologist to the appropriate agencies.
2. Sediment fencing should be installed immediately outside of the proposed disturbed area and the waterbody to prevent sediment-laden water from entering the watercourse.
3. Planting native species within the 15m leave strip is suggested once demo works and infrastructure connections are completed. One larger deciduous tree (5 gallon pot size) for each property such as Garry Oak, native willow, arbutus etc would offer great diversity to the 15m leave strip. Understory plants including Tall Oregon Grape, camas, salal etc would benefit the understory.
4. To ensure peak stormwater flows off the property do not negatively impact the marine environment, Cascadia Biological Services recommends that rock pits be used to limit peak stormwater flows to the ocean. As a result, the rock pit structures should be sized to accommodate the roof surface area and other impermeable areas on the property. Given the small lot sizes and estimated roof area of 300-400 m², rock pits measuring 2mX2mX1.25m (depth) with a volume of 5 cubic meters is required. The length by width by depth measurements above can be changed to accommodate the site as long as the volume (5 cubic meters) is maintained. The rock pits should be place outside of the 15m leave strip however, given the lot constraints, an area within the 15m leave strip may be used for such purposes as long as an equal area is replanted with native vegetation.

If you have any questions regarding this assessment, please do not hesitate to contact me by means below.

Thanks for your time.

Thomas Roy, R.P. Bio., Cascadia Biological Services www.cascadiabiological.com