The Legislature's Request
The 2016 Minnesota Legislature directed the Minnesota Department of Natural Resources (DNR) to request three design-build proposals to augment water levels in White Bear Lake by piping Mississippi River water from Vadnais Lake. The legislation required that the designs ensure water quality in both lakes is not diminished. This includes not allowing invasive species to spread or phosphorus levels to increase.
In October 2016, the DNR solicited proposals from qualified design-build firms. Ultimately, only one consulting/engineering firm, Short Elliott Hendrickson Design-Build, Inc. (SEH Design-Build), a consulting/engineering firm, elected to sign a contract to develop a proposal. SEH partnered with construction contractors and other experts in developing its proposal, which the DNR received on March 31, 2017.
The SEH Design-Build Proposal
SEH's Design-Build proposal includes a two stage approach:
- Stage 1 includes final design and determination of final costs, along with a water quality analysis; and
- Stage 2 includes construction and startup operations.
The SEH proposal includes a detailed water filtration design, detailed alignment layouts, a range of estimated environmental review and permitting costs, detailed construction cost estimates, and estimated operation costs. The proposal also estimates the cost implications of reducing annual pumping capacity from 2 billion to 1 billion gallons and identifies critical areas of remaining uncertainty, including the level of water treatment needed.
The estimated costs for design, construction, permits, basic water treatment, and annual operations and maintenance are summarized below. The estimates are based on projections of mid-point construction costs in 2024.
SEH Estimated Cost*
Preliminary and Final Design
$50,000 - $2,000,000
$350,000 - $2,000,000
Construction and Startup Operations
$44.366 - $47.966 million
Operation and Maintenance
$413,000 per year
*SEH's cost estimates assumed that physical screening (filtration) of the augmentation water will prohibit the transfer of zebra mussel veligers. However, the proposal does not guarantee meeting water quality goals (e.g., phosphorus levels) without further study.
SEH estimates that reducing the design capacity to 1 billion gallons annually would save $4 million, or less than 10 percent, of construction costs.
Water Quality Considerations
The SEH Design-Build team identified water quality as a key risk associated with augmenting water levels in White Bear Lake. Their proposal includes additional pre-project monitoring and analysis to inform final design and evaluate long term risks to water quality of operating an augmentation system.
In order to meet water quality standards and goals, it may be necessary to employ advanced water treatment beyond the basic filtration system included in the cost estimates above.? The higher levels of phosphorus in the Mississippi River and East Vadnais Lake relative to White Bear Lake are a particular concern.? Phosphorus is a nutrient that, in excessive concentrations, can cause algal blooms, loss of water clarity, and other adverse impacts.
A previous concept cost report by SEH estimated that more advanced water quality treatment would increase the capital costs of an augmentation project by $23-40 million, depending on the treatment technology selected. Adding this additional water quality treatment could also increase operation and maintenance costs from $900,000 to $4.1 million/year.
- project owner
- ability to meet water quality goals and requirements
- utility mapping
- soil contamination and other site conditions
- boundary surveys
- easement costs
As noted above, there are significant uncertainties that could increase or decrease the capital and annual operating cost estimates, including the level of water quality treatment needed, unknown underground conditions (e.g., soils, groundwater levels, boundaries of contamination and location of existing utilities), and the amount of water pumped each year.
Questions regarding the SEH Proposal should be directed to Jason Moeckel, DNR, at [email protected] or 651-259-5240.