Tillsonburg Well 1, 2 and 2A Water Treatment Upgrades

Client: 
County of Oxford
Contact: 
Paul Eybergen (519) 539-9800
Brief: 
Tillsonburg Well 1 & 2 Upgrades and Rehabilitation
Year: 
2008
Project: 

Upgrades to the wells located at the Tillsonburg water treatment plant showcase the vast number of skills and services available from Lotowater Technical Services.

Improvement to Existing Infrastructure

This project involved the upgrade of Well 1 & 2. The work required each well to be excavated several meters below grade and the casing to be cut off to facilitate the installation of a pitless adapter, and steel gravel fill tubes which could be used to replace the gravel pack as it settles. A cement cap, followed by a bentonite grout, was installed to seal the annular space. This was designed to maximize the security of the source water that the well draws from, by eliminating the potential for surface water infiltration. A new casing extension along with a vented well cap was then installed to return the casing above grade, and the area surrounding the wells were backfilled.

Well Rehabilitation

With 20 years of experience in the well industry we can confidently classify the mechanism causing well performance decline. With this knowledge we can develop the optimal method of dispersing and removing the fouling agent in question. We offer specialized rehabilitation efforts which are specific to the problems encountered during the preliminary testing and video inspections.

Both rehabilitations at Wells 1 and 2 involved the use of an acid polymer mixture. This method is chosen to dissolve mineral encrustation, as well as biological growth. This treatment in combination with air displacement surging allows deep penetration of the acid into the screened area. Following a period to allow the acid to react, it is subsequently airlifted out of the well with all the additional waste and dissolved mineral.

In addition to the acid treatment at Well 1, an Ener-Jet treatment performed as the video revealed the presence of severe mineral encrustation of the screened portion. This was completed prior to the injection of the acid. The function of this treatment is to make use of a small controlled detonation of a charge in the well. The subsequent shockwave followed by the vapour bubbles which are formed knock loose hardened scale and mineral encrustation. This treatment was very effective in removing the heavy build-up in Well 1.

Well Decommissioning

Well 2A was inspected by Lotowater in preparation for its abandonment. The screened portion of the well was identified and filled with gravel and granular bentonite to ensure the aquifer transmissivity would not be affected by bentonite infiltration. The remaining portion of the well was filled with bentonite slurry to prevent cross contamination between different geologic formations and aquifers.