Environmental Engineering Reference
In-Depth Information
varied widely over various sources, ranging from $1.5 million to $6.6 mil-
lion total cost per kilogram nitrogen removed on a daily basis (Figure 7.17).
The NEBA alternative was formulated to take advantage of this variation,
with the maximum reduction coming from sources with the least expensive
removal costs (feed lots) and none coming from the most expensive (WWTP)
to arrive at the specified 12 kg N/day TMDL (Figure 7.18). This formulation
does take into account nitrogen reduction from some of the most egregious
specific cases, even if the costs are elevated. Urban runoff falls into this cat-
egory, and although addressing the runoff is expensive, it is included in the
NEBA alternative. The result is an alternative that removes more than the
required mass of nitrogen (Figure 7.18) at less than half the cost of the classic
BPT alternative (Figure 7.19).
As is often the case, the impediment to this approach is that several enti-
ties (e.g., the municipality, the feed lot operators, and the regional wastewa-
ter authority) must work closely together and share costs. Even though it is
much more efficient than the classic alternative, under the NEBA approach
the portion of the costs incurred by one entity (e.g., feed lot operators) must
be borne by another entity (regional wastewater authority). Experience has
shown that this is a tough sell, but the objective and analytical approaches
inherent in NEBA and HEA make these tools useful in presenting the case
$7.0
$6.0
$5.0
$4.0
$3.0
$2.0
$1.0
$0.0
WWTP
Urban
storm water
Agricultural
runoff
Feed lot
Total
Nitrogen source
FIGURE 7.17
Cost of nitrogen removal per kg for sources to the Green River.
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