Lowertown Condo: Community warned City about potential for damage in 2011

In 2011, the Lowertown community warned the City of Ottawa and Council about potential issues, namely geotechnical, that could result in damage to homes adjacent to a prospective condo construction development site.  This condo development was subsequently approved and construction began.

In 2014, multiple homes located next to this condo construction site began experiencing damage including sinking floors, gaps and cracks in the walls and in one case, a collapsed ceiling. Numerous construction processes took place directly adjacent to the properties including sheet piling, dewatering as well as drilling.

Below is an excerpt from the 2011 minutes outlining the community’s position. Was the response appropriate? And was this issue later addressed at the Site Plan Control stage?

Comment:

GEOTECHNICAL

  • Dewatering impacts have not been fully addressed relative to the shoreline, the development’s foundation and foundations nearby. There are several concrete examples of how dewatering and blasting have impacted the foundations of this neighbourhood. In addition, due to the clay-based riverbed nature of the land in this area, several homes are already experiencing significant stress on their foundations as the clay continues to settle.
  • Micro-site blasting has not been fully assessed for the impacts it will have on stone and sand foundations. Any blasting that will occur must have area foundations assessed by an engineer, paid for by the developer but sourced by the homeowner to set baseline structural competencies.
  • The parking structure will be below the level of the Rideau River. What are the implications and where will infiltrating water be directed?
  • The consultant notes that “if there are more than two levels of parking” where the program states that there will be three levels of parking. All studies should be based on the assumption that there will be three levels of parking. Assessment of the foundation cannot be undertaken until the number of levels of parking are confirmed as geological strata and engineering properties vary with depth.
  • The Elevations show no parking details i.e. no elevation details below grade. Structures with windows are shown on the roof above the third storey level. Does this provide access to the roof? If roof decks are envisioned, they will be incongruous with the neighbourhood.

Staff Response:

The proposal intends to accommodate the required parking in an underground parking garage. The parking garage is proposed to accommodate 110 parking spaces (residential and visitor). With respect to the dewatering or blasting of the site, these are issues which would be addressed at the Site Plan Control stage. In addition, Rideau Valley Conservation Authority has been circulated the application and has provided the following comments regarding the proposal:

“This development is not within the 1:100 year floodplain of the Rideau River, however the city should ensure that protection is in place relating to the Stormwater and drainage system so that no storm sewer surcharging or flooding would occur as a result of the nearby Rideau River reaching 55.71 metres geodetic, the 1:100 flood elevation.”

The full version of the minutes from 2011 can be found here: http://ottawa.ca/calendar/ottawa/citycouncil/occ/2011/08-25/pec/1%20-%20ACS2011-ICS-PGM-0085%20-%20Zoning%20St%20Andrew%20Street.htm

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