Recycling Treated Municipal Wastewater for Industrial Water Use

Section 3
Inventory of Major WWTPs and Potential Industrial Reuse Demands
Flint Hills Resources is the largest non-power related industrial water user in this
watershed. Approximately 7 mgd was pumped from its well field in 2004 for its total
facility use. They are in the process of system modifications to reuse their process
water rather than add an additional well. Municipal WWTP effluent use at Flint Hills
Resources was evaluated during the facility planning stages of the Met Council’s
Empire WWTP expansion; the outfall for this plant will be moved to discharge into
the Upper Mississippi River watershed and will be within 2 miles of Flint Hills
Resources. While earlier discussions on reclaimed water from Empire were not
pursued because of water quality issues, notably high chlorides in the Empire WWTP
effluent, it is possible that potential future Flint Hills Resources expansions could
consider this source. Also, the industrial areas along the outfall could benefit from this
potential 24 mgd source of reclaimed water. More detailed investigations of this area
will be conducted in Task 2.
Factors Influencing Potential for Industrial Reuse
The majority of the Lower Mississippi River watershed has a good bedrock source
water supply that most communities rely on as their primary water source. Most of
the watershed is in Ground Water Area 3 of the state, with eastern regions in Area 2
and the northern reaches in Area 1. All three areas have a reliable and productive
bedrock aquifer.
Area 3 has extensive near-surface karst areas that result in aquifers being vulnerable
to contamination. There is wide-spread nitrate contamination in near-surface aquifers
as well occurrences of pesticides and other contaminants. The susceptibility to
contamination index places this watershed in the medium to highest range. Area 2 on
the western edge of the watershed has a more productive buried sand aquifer, but
still limited surficial sand aquifers. The northern watershed, in Area 1, has a reliable
supply for all three general aquifer levels.
Portions of the Lower Mississippi River watershed will be affected by the TMDL for
Lake Pepin. The planning process on this TMDL has established preliminary targets
of phosphorus and solids loading reductions of one-half into Lake Pepin. While
nonpoint sources are significant contributions to this load, it is likely that most point
sources will be considered for loading reductions.
Minnesota River
Industrial Water Use
With the exception of water for once through cooling of Xcel Energy’s power plant,
industrial water use in the watershed is dominated by the demands of the agricultural
processing industry. As shown in Figures 3.11a and 3.11b and Table 3.11a, over 60%
of the ground water withdrawals were for agricultural processing facilities. While the
watershed houses a diverse set of industries, most of the other industries have fairly
small demands.
3-18 Craddock Consulting Engineers
In Association with CDM & James Crook
WWReuseTM1_Sec 3_final.doc