Innisfail Sewage Lagoon
Reclamation & Site Grading

Tagish was engaged on this multi-phased project to convert the Town’s existing wastewater lagoons and treatment facility into a new industrial subdivision. Initial phases of the project included environmental testing, decommission and remediation of the treatment facilities, and removal of wet sludge from the lagoons. The objective of the Site Grading phase of the project was to prepare the site for industrial development and obtain final approval on the site’s remediation. A few of the key outcomes on the project included major earthworks to convert the existing lagoon cells to be ready for subdivision development and the construction of a new storm pond.  

Following the removal of the wet sludge material from the lagoon cells, a remediation plan for the remaining dry material in the cells needed to be developed. A rigorous testing and monitoring program was developed that determined the remaining material in the cells could be reclassified as a clay material and did not require offsite disposal. This was a significant cost savings for the project. The grading plan for the subdivision was then prepared to incorporate this material into the site’s layout. This included leveling the site by removing the existing berms and infilling the cells. Preparing a grading plan in this brownfield setting required a strategic approach. A few of these key design considerations included identifying how subpar grading material will be utilized within the earthworks plan and specifying key grading instructions for dealing with existing stockpiled fill material.  With this defined plan it allowed construction to progress efficiently and successfully.  

As a strategy to prepare the site for the major earthworks, an allowance was established in the construction contract to have pre-grading and site preparation work completed the year before the major earthworks was to begin. This allowed the sites drainage to be improved and allowed the work to begin earlier in the season drastically improving construction timelines. With over 250,000m3 of earthworks, this significant project for the Town was completed under budget and on time.