Quebec City launches innovative in situ project for managing sediment-derived phosphorus
Type of initiative
FCM Green Municipal Fund - Plans, Studies, Pilots
Sector
Water
Project value$325,000
Project Type
Pilot Project
Sub Sector
Watershed Management
Grant amount$100,000
Program type
GMF
Municipality
Ville de Québec, QC
Status
Fully Disbursed
Population
549,459
Project timeline
2008 - 2012
Project number
10168
Description
Quebec City piloted field tests to assess the feasibility and effectiveness of two promising techniques for restoring Lac Saint-Augustin where eutrophication was a serious problem and likely to cause cyanobacteria bloom. One of the pilot tests involved precipitation of the phosphorus contained in the water near the bottom of the lake and neutralization of recovered sediment, while the other pilot test involved precipitation of phosphorus followed by sediment extraction by pumps for treatment and disposal. Testing also assessed the salting out rate for old and recent sediment for both techniques studied. A technical and socioeconomic evaluation, including a preliminary environmental impact study, compared the two techniques so the best option could be selected.
The goal of the project was to find a viable solution that would restore acceptable water quality to Lac Saint-Augustin. The phosphorus concentration in the water was 70 micrograms per litre (μg/l). The objective of a large-scale post-field-test project was to reduce the phosphorous level to 10 μg/l, which was the concentration in the lake at the turn of the century. There are not many examples in Canada of in-situ management of phosphorous in sediment and the results of this pilot project are of value for municipalities facing similar problems. This study project aimed to find an appropriate technique for restoring Lac Saint-Augustin and the water quality of this urban lake for its residents. The study results were presented at a conference organized by Quebec City in 2010, and at various other venues.
(Project description from original funding application)
Applicant
Ville de Québec, QC