Fishers Lane Treatment Facility
In 2005, the 60-year old Fishers Lane drinking water treatment facility was identified as needing substantial rehabilitation to extend its useful life. The Fishers Lane facility treated surface water drawn from the Cowlitz River. It was estimated to cost $52.6 million to fix the plant’s major issues, which included:
Mint Farm Regional Water Treatment Plant
A team of experts was hired in 2006 to explore water supply options. After nearly four years of extensive analysis and testing, the City and BHWSD decided to develop a new groundwater supply and treatment facility at the Mint Farm Industrial Park. The total cost to switch to the new source was $34 million.
The Mint Farm Regional Water Treatment Plant (MFRWTP) began serving Longview area water customers in January 2013. The new facility uses groundwater from wells and a new treatment system for the groundwater. This new treatment method is significantly different than the process at Fishers Lane, which uses the Cowlitz River as source water. Mint Farm can produce 17.5 million gallons per day (MGD) of drinking water, which allows about six MGD of capacity for new growth.
The transition from the Cowlitz River surface water source to groundwater at the Mint Farm water treatment facility has been complicated. The Mint Farm groundwater has different water chemistry and very little dissolved oxygen. The new treatment plant is also located on the opposite side of the city, which changed the flow direction in some parts of the water distribution system. These change resulted in significant dissolving of iron and manganese scale that had built up in the pipes over many years. In addition, the Mint Farm groundwater has higher levels of hardness and dissolved silica than the Cowlitz River water, resulting in mineral deposits and spotting. We have implemented some treatment modifications and increased water main flushing to improve water quality, but some issues remain.
While the new system provides water that meets all water safety and quality standards, the City and BHWSD are concerned about the high level of customer dissatisfaction with the current water quality.
The high level of customer dissatisfaction highlighted the need for a detailed examination of ways to improve our drinking water. In 2014, an independent engineering firm was hired to evaluate options to improve water quality and a Customer Advisory Committee (CAC) was convened. The CAC’s goal was to provide a recommendation for sustainable, safe and satisfactory water supply. Ultimately, the committee recommended to explore returning to the Cowlitz River as a source of water using riverbed collector wells. This recommendation was presented to the City Council and BHWSD Commissioners on August 20, 2015. (Find more information on the CAC’s process here.)
In October, 2015, the City Council approved a contract to analyze three potential sites for a new water supply along the Cowlitz River using riverbed collector wells. The findings essentially eliminated two sites from consideration due to capacity limitations. One site remained a possibility but showed elevated mineral content (iron, silica, etc.) which raised concern about long-term water quality. Due to these disappointing results from the first three sites, a fourth potential test site was identified. The results of the initial investigation were first shared with the CAC and later formally presented to the City Council and BHWSD in March, 2016.
In June, 2016, additional exploration was completed at a fourth site. Findings showed the fourth site outperformed the other three in terms of capacity but iron, manganese, hardness and silica were present at similar or higher levels than the current Mint Farm source. Additional testing would be required to find out whether these water quality issues could be improved over time by drawing surface water influence from the Cowlitz River and displacing groundwater.
On July 28, 2016 the City Council and BHWSD reviewed test results and considered the alternatives (download water quality test results and comparison, PDF 128 kb). Pursuing the possibility of a Cowlitz River source would require high volume, long-term pump testing to determine whether water quality might improve over time. The costs associated with this proposal totalled between $180,000 and $435,500. With no guarantee of improvement, City Council and BHWSD decided to cease further investigation of Cowlitz River collector wells and reconsider options to upgrade treatment at the Mint Farm.
The City and BHWSD are currently looking into additional treatment processes to improve water quality from the Mint Farm and address some of the issues that have concerned customers. Later this year, staff will recommend next steps to address taste and odor complaints and propose methods to evaluate treatment options for silica removal. Download a schedule of work.