[Code of Federal Regulations]

[Title 40, Volume 21]

[Revised as of July 1, 2006]

From the U.S. Government Printing Office via GPO Access

[CITE: 40CFR125.93]



[Page 346-349]

 

                   TITLE 40--PROTECTION OF ENVIRONMENT

 

         CHAPTER I--ENVIRONMENTAL PROTECTION AGENCY (CONTINUED)

 

PART 125_CRITERIA AND STANDARDS FOR THE NATIONAL POLLUTANT DISCHARGE 

ELIMINATION SYSTEM--Table of Contents

 

Subpart J_Requirements Applicable to Cooling Water Intake Structures for 

      Phase II Existing Facilities Under Section 316(b) of the Act

 

Sec.  125.93  What special definitions apply to this subpart?



    In addition to the definitions provided in Sec.  122.3 of this 

chapter, the following special definitions apply to this subpart:

    Adaptive management method is a type of project management method 

where a facility chooses an approach to meeting the project goal, 

monitors the effectiveness of that approach, and then based on 

monitoring and any other relevant information, makes any adjustments 

necessary to ensure continued progress toward the project's goal. This 

cycle of activity is repeated as necessary to reach the project's goal.

    Annual mean flow means the average of daily flows over a calendar 

year.

    All life stages means eggs, larvae, juveniles, and adults.

    Calculation baseline means an estimate of impingement mortality and 

entrainment that would occur at your site assuming that: the cooling 

water system has been designed as a once-through system; the opening of 

the cooling water intake structure is located at, and the face of the 

standard \3/8\-inch mesh traveling screen is oriented parallel to, the 

shoreline near the surface of the source waterbody; and the baseline 

practices, procedures, and structural configuration are those that your 

facility would maintain in



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the absence of any structural or operational controls, including flow or 

velocity reductions, implemented in whole or in part for the purposes of 

reducing impingement mortality and entrainment. You may also choose to 

use the current level of impingement mortality and entrainment as the 

calculation baseline. The calculation baseline may be estimated using: 

historical impingement mortality and entrainment data from your facility 

or from another facility with comparable design, operational, and 

environmental conditions; current biological data collected in the 

waterbody in the vicinity of your cooling water intake structure; or 

current impingement mortality and entrainment data collected at your 

facility. You may request that the calculation baseline be modified to 

be based on a location of the opening of the cooling water intake 

structure at a depth other than at or near the surface if you can 

demonstrate to the Director that the other depth would correspond to a 

higher baseline level of impingement mortality and/or entrainment.

    Capacity utilization rate means the ratio between the average annual 

net generation of power by the facility (in MWh) and the total net 

capability of the facility to generate power (in MW) multiplied by the 

number of hours during a year. In cases where a facility has more than 

one intake structure, and each intake structure provides cooling water 

exclusively to one or more generating units, the capacity utilization 

rate may be calculated separately for each intake structure, based on 

the capacity utilization of the units it services. Applicable 

requirements under this subpart would then be determined separately for 

each intake structure. The average annual net generation should be 

measured over a five year period (if available) of representative 

operating conditions, unless the facility makes a binding commitment to 

maintain capacity utilization below 15 percent for the life of the 

permit, in which case the rate may be based on this commitment. For 

purposes of this subpart, the capacity utilization rate applies to only 

that portion of the facility that generates electricity for transmission 

or sale using a thermal cycle employing the steam water system as the 

thermodynamic medium.

    Closed-cycle recirculating system means a system designed, using 

minimized make-up and blowdown flows, to withdraw water from a natural 

or other water source to support contact and/or noncontact cooling uses 

within a facility. The water is usually sent to a cooling canal or 

channel, lake, pond, or tower to allow waste heat to be dissipated to 

the atmosphere and then is returned to the system. (Some facilities 

divert the waste heat to other process operations.) New source water 

(make-up water) is added to the system to replenish losses that have 

occurred due to blowdown, drift, and evaporation.

    Cooling water means water used for contact or noncontact cooling, 

including water used for equipment cooling, evaporative cooling tower 

makeup, and dilution of effluent heat content. The intended use of the 

cooling water is to absorb waste heat rejected from the process or 

processes used, or from auxiliary operations on the facility's premises. 

Cooling water that is used in a manufacturing process either before or 

after it is used for cooling is considered process water for the 

purposes of calculating the percentage of a facility's intake flow that 

is used for cooling purposes in Sec.  125.91(a)(4).

    Cooling water intake structure means the total physical structure 

and any associated constructed waterways used to withdraw cooling water 

from waters of the U.S. The cooling water intake structure extends from 

the point at which water is withdrawn from the surface water source up 

to, and including, the intake pumps.

    Design and construction technology means any physical configuration 

of the cooling water intake structure, or a technology that is placed in 

the water body in front of the cooling water intake structure, to reduce 

impingement mortality and/or entrainment. Design and construction 

technologies include, but are not limited to, location of the intake 

structure, intake screen systems, passive intake systems, fish diversion 

and/or avoidance systems, and fish handling and return systems. 

Restoration measures



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are not design and construction technologies for purposes of this 

definition.

    Design intake flow means the value assigned (during the cooling 

water intake structure design) to the total volume of water withdrawn 

from a source waterbody over a specific time period.

    Design intake velocity means the value assigned (during the design 

of a cooling water intake structure) to the average speed at which 

intake water passes through the open area of the intake screen (or other 

device) against which organisms might be impinged or through which they 

might be entrained.

    Diel means daily and refers to variation in organism abundance and 

density over a 24-hour period due to the influence of water movement, 

physical or chemical changes, and changes in light intensity.

    Entrainment means the incorporation of any life stages of fish and 

shellfish with intake water flow entering and passing through a cooling 

water intake structure and into a cooling water system.

    Estuary means a semi-enclosed body of water that has a free 

connection with open seas and within which the seawater is measurably 

diluted with fresh water derived from land drainage. The salinity of an 

estuary exceeds 0.5 parts per thousand (by mass) but is typically less 

than 30 parts per thousand (by mass).

    Existing facility means any facility that commenced construction as 

described in 40 CFR 122.29(b)(4) on or before January 17, 2002; and any 

modification of, or any addition of a unit at such a facility that does 

not meet the definition of a new facility at Sec.  125.83.

    Freshwater river or stream means a lotic (free-flowing) system that 

does not receive significant inflows of water from oceans or bays due to 

tidal action. For the purposes of this rule, a flow-through reservoir 

with a retention time of 7 days or less will be considered a freshwater 

river or stream.

    Impingement means the entrapment of any life stages of fish and 

shellfish on the outer part of an intake structure or against a 

screening device during periods of intake water withdrawal.

    Lake or reservoir means any inland body of open water with some 

minimum surface area free of rooted vegetation and with an average 

hydraulic retention time of more than 7 days. Lakes or reservoirs might 

be natural water bodies or impounded streams, usually fresh, surrounded 

by land or by land and a man-made retainer (e.g., a dam). Lakes or 

reservoirs might be fed by rivers, streams, springs, and/or local 

precipitation.

    Moribund means dying; close to death.

    Natural thermal stratification means the naturally occurring and/or 

existing division of a waterbody into horizontal layers of differing 

densities as a result of variations in temperature at different depths.

    Ocean means marine open coastal waters with a salinity greater than 

or equal to 30 parts per thousand (by mass).

    Once-through cooling water system means a system designed to 

withdraw water from a natural or other water source, use it at the 

facility to support contact and/or noncontact cooling uses, and then 

discharge it to a waterbody without recirculation. Once-through cooling 

systems sometimes employ canals/channels, ponds, or non-recirculating 

cooling towers to dissipate waste heat from the water before it is 

discharged.

    Operational measure means a modification to any operation at a 

facility that serves to minimize impact to fish and shellfish from the 

cooling water intake structure. Examples of operational measures 

include, but are not limited to: reductions in cooling water intake flow 

through the use of variable speed pumps and seasonal flow reductions or 

shutdowns; and more frequent rotation of traveling screens.

    Phase II existing facility means any existing facility that meets 

the criteria specified in Sec.  125.91.

    Source water means the waters of the U.S. from which the cooling 

water is withdrawn.

    Supplier means an entity, other than the regulated facility, that 

owns and operates its own cooling water intake structure and directly 

withdraws water from waters of the United States. The supplier sells the 

cooling water to other facilities for their use, but may also use a 

portion of the water itself.



[[Page 349]]



An entity that provides potable water to residential populations (e.g., 

public water system) is not a supplier for purposes of this subpart.

    Thermocline means the middle layer of a thermally stratified lake or 

a reservoir. In this layer, there is a rapid change in temperatures 

between the top and bottom of the layer.

    Tidal river means the most seaward reach of a river or stream where 

the salinity is typically less than or equal to 0.5 parts per thousand 

(by mass) at a time of annual low flow and whose surface elevation 

responds to the effects of coastal lunar tides.



    Effective Date Note: At 71 FR 35040, June 16, 2006, Sec.  125.93 was 

amended by revising the definition of ``existing facility'', effective 

July 17, 2006. For the convenience of the user, the revised text is set 

forth as follows:



Sec.  125.93  What special definitions apply to this subpart?



                                * * * * *



    Existing facility means any facility that commenced construction as 

described in 40 CFR 122.29(b)(4) on or before January 17, 2002 or July 

17, 2006 for an offshore oil and gas extraction facility); and any 

modification of, or any addition of a unit at such a facility that does 

not meet the definition of a new facility at Sec.  125.83.



                                * * * * *