POWER June 2014 - 25

WATER REGULATIONS
lows an IM retrofit. (See sidebar " Schedule to Avoid Double Jeopardy? "
for the implications of a possible alternative sequence.)
The final rule also will likely offer the potential to demonstrate
that some combination of existing and newly installed technologies
and operational measures reduces IM to a " level commensurate with
closed-cycle cooling. " The level anticipated is an approximately 75%
reduction in IM relative to an unmitigated CWIS. The applicant must
demonstrate this level of reduction to the satisfaction of the NPDES
Director, likely through some combination of literature-based assessment
and monitoring in the field.
The expected final rule also allows the NPDES Director to find that
a CWIS is BTA when it impinges a de minimis quantity of fish per
year, potentially defined as equal to or less than 1,000 fish per year.
Although this would be an attractive alternative for the small number
of facilities that qualify, the benefit should be weighed against the
cost and risk of any ongoing monitoring required.
As we consider the IM BTA options, it is useful to consider several
questions relative to the facility and its CWIS:
■ Does the CWIS already match any of the technologies that confer
BTA? Unfortunately for most of the facilities covered by the now
suspended 316(b) Phase II rule, the answer to this question is likely
to be " no. "
■ Does the existing CWIS contribute meaningfully to the reduction
of impingement mortality in ways that are not defined by the BTA
technologies? For example, does it draw water from an area with
low fish densities relative to other nearby locations? If it does, can
that reduction be reliably and cost-effectively quantified as part of
the combination approach? What additional measures might be instituted
to reach the percentage reduction specified in the final rule
or de minimis thresholds?
■ What are the approximate site-specific costs and constraints on the
impingement BTA technologies? Are some technologies precluded by
cost of installation and operation (such as retrofit to closed-cycle cooling)
or by other issues (including lack of access to shoreline property
necessary to expand the CWIS and reduce through-screen velocity)?
■ When necessary, how will optimization and/or compliance monitoring
affect the cost of the measure as well as the risk to compliance?
For example, the proposed 316(b) rule of 2011 called for ongoing
demonstration that post-impingement survival for Ristroph-type
screens was, on average, higher than 88% for species of concern.
Given variations in survival rates, such a standard presented unacceptable
risks to compliance. Though the final rule's anticipated
reliance on optimization of post-impingement survival is less risky,
it would lead to additional costs and should be managed with the
agency so that minimum survival rates are not required.
■ Do the IM BTA approaches contribute substantially to reductions
in EM? We believe that facilities employing closed-cycle cooling
should be considered compliant with the EM BTA even in the rare
cases when actual intake flows exceed 125 mgd. Other measures that
contribute to reduced IM may also meaningfully reduce the rates of
EM. These include use of wedgewire screens (such as the one shown
in the photo at the top of this article) with reduced through-slot velocity
that have been shown to also reduce entrainment rates, as well
as placement of intakes in habitat that have reduced populations of
both impingeable and entrainable organisms.
■ In short, what approach or combination of approaches confers reliable
compliance at the lowest cost and lowest risk? In many cases,
there will be a clear winner when all factors point to a single BTA
approach. In others, the best approach may require compromising
one factor, for example, cost of installation and operation, in favor
of another, such as regulatory certainty. We should expect that such
factors may be difficult to compare quantitatively (for example,
June 2014 | POWER
capital cost vs. certainty of compliance) and that, in some cases,
risk analysis may be warranted.
These questions must be first addressed within the internal project
team in order to define the compliance strategy and the best approach
to BTA for IM. The answers should also be soundly and convincingly
presented to the regulatory agencies using the reports and analyses
called for by the final rule and in full consideration of the conditions
present at a site.
BTA Approach for Entrainment Mortality
All indications are that the final rule's approach to considering BTA
for EM will be appropriately dominated by site-specific factors. For
facilities explicitly captured by the EM standards in the final national
rule-expected to be those with an actual intake flow of 125 mgd or
greater-four reports will be required to help the NPDES Director
assess BTA at an affected facility:
■ The reports called for under 40 Code of Federal Regulations
(CFR)122.21(r)(9)-or report (r)(9)-will define a program for
documenting the rates of EM of fish and shellfish, including listed
species, and then implement that program to document the rates.
■ The (r)(10) report will present the technical feasibility and costs
(both facility-level and social) of technologies that could reduce
EM, including retrofit to closed-cycle cooling.
■ The Benefits Valuation Study-or (r)(11) report-evaluates the
monetized and nonmonetized benefits of EM reductions associated
with different mitigation measures.
■ The (r)(12) report-or Non-water Quality and Other Environmental
Impacts Study-must present a site-specific discussion of other
effects of EM mitigation measures such as potential increased air
emissions and water consumption.
Table 1. Site-specific factors that may affect costs
and benefits of entrainment mortality reduction measures.
" Costs " are those that occur at the facility level, both positive
and negative, while " benefits " (again both positive and negative) occur
in the environmental and social context. Source: ECT Inc.
Factor(s)
High rates of entrainment, presence
of listed species, commercial/recreational
species, potential ecosystem
level effects
Decrease in thermal impacts
Decrease in thermal refuge and winter
fishery
Increased cost of retrofit and operation
Increased
ease of retrofit
Increased performance and reliability
of technology
Reduced plant efficiency, increased
emissions/MW
Decrease in grid reliability
Increase in power prices
Increase in consumptive water use
Increase in noise and other environmental
impacts
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Report per 40
CFR 122.21(r)
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11, 12
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Costs Benefits
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POWER June 2014

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