The Fairmont Water Treatment Plant (WTP) was experiencing treatment capacity limitations as well as challenges related to aging infrastructure, including operational difficulties related to deteriorating and outdated treatment processes. Proposed drinking water regulations would likely require improvements or advanced treatment processes to be implemented in the future at the WTP.
To address these challenges, the City retained AE2S to complete a Facility Master Plan, designed to include population and water demand projections, evaluation of current and future drinking water regulations, establishment of treatment target goals, completion of a source water evaluation, a WTP condition assessment and risk analysis, a treatment technology evaluation, and development of preferred project alternatives for evaluation.
Rehabilitation of the existing facility, as well as total replacement, were evaluated. Due to the significant capital investment for renewal or replacement of the existing WTP, thorough consideration of potential reuse of in-place infrastructure was a high priority. Thus, a major component of master planning involved completion of in-depth facility and equipment condition assessment, and subsequent completion of a risk analysis. Each project option considered was evaluated with respect to capital and life cycle costs, treatment effectiveness, process redundancy, operation and maintenance requirements, and constructability. Based on these factors, decommissioning of the existing facility and construction of a new WTP was recommended.
Following completion of the Master Plan, AE2S initiated an on-site pilot treatment operation that was designed specifically to comparatively analyze the Taste and Odor (T&O) mitigation performance of Ultraviolet light (UV) and Hydrogen Peroxide (H2O2), ozone, and Granular Activated Carbon (GAC). Analysis included “spiking” pilot water with increased concentrations of T&O compounds to evaluate performance under worst case conditions.
In addition to analytical evaluation, performance of the alternative technologies was evaluated by an “Odor Panel” consisting of WTP staff, City officials, residents, and engineers. Participation not only assisted in process selection, but also improved public support for the project.
The project also arranged and facilitated an on-site pilot test for Dissolved Air Flotation (DAF) technology for improved algae removal. Ultimately, DAF was excluded from final design, as the costs outweighed the benefits.
Following a collaborative design process, construction of the new WTP began in July 2011. The WTP began operations in August 2013. The 5.4 million gallon per day (MGD) facility includes the following treatment processes: raw water aeration, conventional lime and soda ash softening, a filter press solids handling process, conventional sand filtration, GAC filtration, on-site generation of sodium hypochlorite for chlorine disinfection, and eight additional chemical feed systems. Interesting project components include demolishing an existing school to make way for the new facility location, rehabilitating and reusing the existing raw water intake station, intermediate pumping station, high service pumping station, and demolishing the existing facility and restoring the adjacent lake shoreline.