Wellhead Treatment
Background
The Aquifer that supplies the City’s water system has a very high Iron concentration this can cause rust colored discoloration to the water delivered to homes. The high iron level is not a health concern it is more of an aesthetic problem that can be frustrating for residents. Recently the Minnesota Department of Health has issued new health guidelines regarding Manganese levels, the City has conducted resident water sampling in the Old Village, which has shown elevated Manganese levels. The Northeast supply system is below the new manganese recommended levels.
Currently the City treats the raw water with chemicals at the well before it is released into the water distribution system. The chemical treatment is effective to a degree, but cannot remove all of the Iron content from the water at the elevated concentrations present in the aquifer. To successfully remove all of the Iron the water needs to be filtered for the particulate material.
Solutions
Staff worked with a consultant who specializes in water quality solutions, to identify solutions to the water quality issue. There are two options that have been identified which would allow the City of Dayton to control the quality of water being delivered to residents.
- Build a centralized water treatment plant. The plant would serve the Northeast and Northwest population of Dayton. This is a big project with an estimated cost for the plant of $35,000,000. There would also be substantial cost of extending water main from the Old Village to the North East location of the water treatment plant and possibly additional water main from the existing wells in the North East to the treatment facility. This treatment plant would be sized for the full build out water consumption which would not be required for many years.
- Construct a smaller well head water treatment plant, that could treat up to two wells. This facility would be built in the location of the wells and would not require the Northeast and Northwest systems to be connected to each other. This solution is scalable so facilities are only built as they are required to maintain peak water service. The project cost per facility is around $6,000,000.
Finance
Funding for the project would come from the Water Utility Fund, which is funded from Development projects and water usage billing. The improvements would be funded from residents who are served by the Municipal water system. There would be no tax increases to pay for these improvements. Staff successfully applied for Federal and State Grant Funding for the projects, and were awarded a total of $5,750.000.
Actions
The construction phase of the project has recently begun, the project is expected to be substantially complete by January of 2025. The City has also recently drilled a new Well in the Riverwalk development, which will combine with flow from the existing well 4 to feed water into the water treatment plant.
Construction Progress
04-08-2024 Well Head Treatment Plant Update
Site Activities as of 4/8/24:
- Rebar for operating slab has been installed
- Plumbing and electrical in-slab items are nearly complete
Two week look ahead (as Magney has communicated to me):
- Finish plumbing and in-slab conduit work, grounding wire and floor drains are last items to complete
- Pour operating floor slab (weather permitting)
03-11-2024 Well Head Treatment Plant Update
Site Activities:
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- Shoring system for suspended operating slab has been installed
- Below slab piping has been installed
- Rebar for operating slab is starting to be installed
- Wall form tie holes have been patched/filled
- Concrete fill has been added to the basins to slope the floor
Two Week Look Ahead:
-
- Tie rebar for operating floor slab
- Install forms for operating floor slab
- Pour operating floor slab
02-12-2024 Well Head Treatment Plant Update
Site Activities:
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- Poured concrete 2/1 for basin walls on South End
- South basin walls have been curing since the pour
- Concrete fill install has started in each basin to make the sloping floor
- General site maintenance (mud removal/cleanup, laying base rock, etc.)
Two Week Look Ahead:
-
- Pour/finish concrete fill to get floor slope
- Install shoring system for suspended operating floor slab
- Tie rebar for operating floor slab
- Install forms for operating floor slab
Magney has also continued to send in shop drawings covering a variety of equipment, and submitted a few RFI’s for clarifications on various items over the past two weeks.
01-24-2024 Well Head Treatment Plant Update
Site Activities:
-
- Base slab has been curing after 12/28/23 concrete pour
- Tying rebar for basin walls
- Concrete form installation for basin walls
- Pouring concrete 1/22 for basin walls on North End
Two Week Look Ahead:
- Keep North Basin walls blanketed and warm to cure
- Tie rebar for South basin walls
- Install forms for South basin walls
- Pour concrete for South basin walls (shooting for 1/31 or first week of Feb)
In addition to site activities, Magney has sent in the Filtration Equipment shop drawing, which is being reviewed. They have also been responding to previously returned shop drawings and sending in a bunch of others covering equipment/materials for upcoming work.
01-24-2024 Well Head Treatment Plant Update
Site Activities:
-
- Base slab has been curing after 12/28/23 concrete pour
- Tying rebar for basin walls
- Concrete form installation for basin walls
- Pouring concrete 1/22 for basin walls on North End
Two Week Look Ahead:
- Keep North Basin walls blanketed and warm to cure
- Tie rebar for South basin walls
- Install forms for South basin walls
- Pour concrete for South basin walls (shooting for 1/31 or first week of Feb)
In addition to site activities, Magney has sent in the Filtration Equipment shop drawing, which is being reviewed. They have also been responding to previously returned shop drawings and sending in a bunch of others covering equipment/materials for upcoming work.
01-10-2024 Well Head Treatment Plant Update
Site Activities:
-
- Base Slab and floor poured
- Wall Forms are set
- Wall steel (rebar) is being tyed
- Walls being poured 1/11/24
Two Week Look Ahead:
- Remove wall forms
- Start setting wall forms for South half of tank
In addition to site activities, Magney has continued to send in shop drawings and respond to our previously returned shop drawings.
12-12-2023 Well Head Treatment Plant Update
Site Activities:
-
- Earth Retention System is fully installed
- Excavation is complete down to final elevation for building base slab and footings
- All excavated material is stockpiled in park area
- Base rock is being installed and compacted
- Small amount of groundwater is seeping out of the walls, being dewatered via a rock trench to keep excavation dry
- AET tested subgrade on 12/7 and it was deemed adequate for supporting the building
Two Week Look Ahead:
- Install formwork for base slab and footings
- Install reinforcing steel for base slab and footings
- Pour base slab and footings concrete (Scheduled for 12/19 currently)
In addition to site activities, Magney has continued to send in shop drawings and respond to our previously returned shop drawings.
