The Big Sandy Mountaineer -

Town of Big Sandy Council discusses changes needed to new water system

 

February 19, 2020

The new Storm Drain Project will require a public meeting before any grant submission. The Grant is due late March. In looking at different grants and the requirements for each requires public input. They have scheduled the general meeting for March 12. Planning tools needed include revisiting the Big Sandy Growth Policy 2008 and the Capital Improvement Plans, which makes assessments of our community and helps set priorities. The Capital Improvement was done for five years from 2007 through 2012. Bear Paw Development will review and present a rough draft to the city council at their next meeting before it is given to the public.

Dan Richardson, PE, CFM, an engineer from KLJ, handed out a draft brief discussion paper on what will be required when the North Central Montana Regional Water Authority (NCMRWA) system reaches Big Sandy.

I have included a portion of that presentation here. "Big Sandy is scheduled to connect to the North Central Montana Regional Water Authority (NCMRWA) system. The NCMRWA could either supplement or replace the water produced by the Big Sandy wells. This report discusses the potential impacts on Big Sandy involved with connecting to the NCMRWA system. Within the report, we also discuss options for incorporating the existing water system with the water provided by the NCMRWA."

The report included existing conditions in Big Sandy. "Currently Big Sandy gets its water from three wells located east of the town. The total yield of the wells is 540 gallons per minute. The amount of water supplied by the wells is not adequate to provide water for fire protection. A 500,000-gallon partially buried concrete water tank located on the northwest side of the town makes up the difference between the water provided by the wells and fire flow demand."

"Water from the wells is pumped through a treatment building. Within the treatment building, a Sodium Polyphosphate and a Sodium Hypochlorite are injected into the water. According to documents on file at Montana DEQ, the town voluntarily treats its water with Sodium Polyphosphate to treat for hardness and sequester iron and manganese. Currently, hardness is not a regulated contaminant that is required to be mitigated by the Montana Department of Environmental Quality (MDEQ)." However, during the discussion, the reason it is added to the water in Big Sandy is not because of the hardness of the water, but because of the depth of the well, which does require it. "Polyphosphates can promote bacteria growth within a water system. So, whenever a polyphosphate is added to public water system, a disinfectant, such as chlorine, must also be added. The Town of Big Sandy uses a sodium hypochlorite (chlorine) product called to provide residual disinfection within the water distribution system. The chlorine is added to the system to provide residual disinfection as required/recommended when systems inject a polyphosphate."

"The water treatment building was installed in its current location in 2007. Big Sandy has a Supervisory Control and Data Acquisition (SCADA) system that is very old and no longer functions as intended. This system should be upgraded to assist operators with the maintenance of the system."

"The NCMRWA was originally going to provide water at the existing Big Sandy well house. Due to several issues and costs associated with installing a water main to the well house, NCMRWA is now planning on connecting to Big Sandy's water system at the water tank. NCMRWA is not planning on adding polyphosphate to the water that will be delivered to Big Sandy."

"NCMRWA water will be initially disinfected with chloramine instead of chlorine. The reason is the time it will take to get water to Big Sandy will be between 5 and 7 days. Chloramine is more stable than chlorine and will provide disinfection for that length of time, while chlorine would tend to degrade substantially and could be ineffective after five days."

"A new building will need to be installed next to the water tank to meter the water being used from the NCMRWA. In addition, the new building could contain a disinfection system necessary to increase the amount of disinfectant in the water before it is discharged into the Big Sandy water tank."

"Once NCMRWA is connected to Big Sandy's water tank, Big Sandy will need to decide what to do with their existing system. Fortunately, there is not a current requirement to treat the water from the Big Sandy wells. This yields several low-cost options, as well as time to seek DEQ approvals and make improvements as required."

During their analysis of the system, they offered four alternatives, "Alternative 1. Add ammonia to the current system to form chloramine. Chloramine is formed by mixing chlorine and ammonia. A new ammonia injection system could be added to the existing well house, to form chloramine. This would be intended to match the disinfection that will likely be provided by NCMRWA. The current well house has enough space that an ammonia system could be added to the treatment building without requiring modifications to the building."

"One of the significant issues with this alternative is the amount of contact time required for water that uses chloramine for disinfection requires a longer contact time than water disinfected with chlorine. The contact time required for chlorine disinfection is usually less than 10 minutes. Contact time for water disinfected with chloramine is over 4,000 minutes. However, since the Big Sandy water is being disinfected due to the addition of a polyphosphate, MDEQ may allow chloramine disinfection. The cost of adding the ammonia tank and another metering pump, would be approximately $12,000 plus the cost of engineering to obtain MDEQ approval."

"This alternative would work best if the amount of water that is being supplied by NCMRWA and Big Sandy is roughly the same quantity."

"Alternate 2. Continue to operate the system with Chlorine and Polyphosphate. This alternative would not change the current Big Sandy water system. It would place the NCMRWA system in the role of providing supplemental water to the Town of Big Sandy. Any water demands that could not be met by the current water system would be made up by the NCMRWA water. The issue with this alternative is combining water with two different disinfectants. Mixing chlorinated water with water that has chloramine may create some issues. The system would need to be closely monitored after the addition of the NCMRWA water was added to ensure that none of these effects are realized."

"This alternative would work well if the Big Sandy water system provided a substantial majority of the water. Based on the current use, the Big Sandy wells provide adequate water for the domestic and irrigation use by the town, so there would be very little NCMRWA water introduced into the system."

"It is assumed the amount of residual chloramine will be so low there would be very little impact on the system."

"A significant disadvantage is the alternative is the Big Sandy water system would have very limited potential for expansion. There could not be new users added to the system without increasing the risks of mixing the two disinfectants. This is an alternative that we would not recommend as a long-term solution."

"Alternative 3. Continue to operate the water system without adding polyphosphate and chlorine

This option is available because there is currently no requirement for Big Sandy to add polyphosphate to the system. Once polyphosphate is stopped being added to the water system, there will no longer be a need to add a disinfectant. Since it is not known how much mixing of the water will occur within the system, the effects of hardness are difficult to predict. However, usually, hardness is treated by water softeners inside of individual buildings. If, after some time, there are noticed effects, polyphosphate and chlorine could be added back at the current well house."

"This alternative would work best if the amount of water supplied by NCMRWA is significantly greater than the amount that is provided by Big Sandy."

"Alternative 4. Change the well field to irrigation and reduce the salinity in the sewer lagoons. There have been some issues with high salinity within the Big Sandy sewer lagoon, which then causes issues with the crop production when the wastewater is used for irrigation. Changes to the water distribution system could be made so water is provided to the sewer lagoon and decrease the salinity in the wastewater."

The grants for a side walk from the Recreational Trails Program (RTP) through Fish Wildlife and Parks has been completed. We will find out in April the results of that grant application.

The auditors have completed their review of Big Sandy, and the commissioners are waiting on their final report. However, they did recommend a time clock for the swimming pool.

The town's budget was reviewed and revised.

It was noted by this reporter that even though several individuals have asked that we publish the agenda of the meeting, as we did. There were no guests, no residents of Big Sandy at the councils meeting.

 
 

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