
                                  MEMORANDUM

Tetra Tech, Inc.
10306 Eaton Place, Suite 340
Fairfax, VA 22030
phone	703-385-6000
fax	703-385-6007


DATE: 		July 3, 2008

TO:			Paul Shriner and Jan Matuszko, EPA
	
FROM:		Christine Wong, Kelly Meadows and Shari Goodwin, Tetra Tech

SUBJECT:	Design Intake Flow for Test Cooling Water Intake Structures

Introduction
After reviewing technology efficacy studies in the June 23, 2008 memo from Battelle for impingement mortality data, EPA and Tt identified 6 studies that best represent the efficacy of Ristroph-type coarse mesh traveling screens.  To enable the development of technology-based limits, EPA requested that Tt determine the intake flows that correspond to the study periods in these documents.  None of the studies were completely clear in describing the test conditions, including the intake flows withdrawn during testing.  As such, Tt was tasked with determining an estimate of the flow rates.  Tt reviewed the studies and other supporting documentation (including summary reports, primary studies, and information from industry surveys) to determine the design intake flow (DIF) of the cooling water intake structures (CWIS) tested.  The results of Tt's study reviews are presented in the table on the following page.

Degree of Confidence
Tt is reasonably confident that the DIFs for the Dunkirk and Huntley studies are correct, because the design capacity is explicitly stated for the study screens at each facility.  (Whether the screens operated at the DIF for the entire study period is unknown; Tt is assuming they were.)

Based on the information available, Tt used its best professional judgment to assign a CWIS-specific DIF to the Arthur Kill and Salem studies.  Tt has attempted to contact representatives at both facilities to confirm these assumptions.  At this time, communication efforts have not been successful with either facility.  If and when contact is made with the facility representatives and DIF assumptions are confirmed, Tt will amend the table as necessary.

Facility Name
Generating Units/CWISs
DIF for Test CWIS Screens
Notes
Data Source(s)
Arthur Kill
Unit 20
87 MGD
Each unit contains 4 screens; only one of the four screens was upgraded for the study.  No information provided on unit operation during study; assume that the flow through the upgraded test screen was 0.25 the maximum flow for the unit (347.9 MGD  -  provided in study), or 87 MGD.
EPRI 2007

Unit 30
85 MGD
Each unit contains 4 screens; only one of the four screens was upgraded for each study.  No information provided on unit operation during study; assume that the flow through the upgraded test screen was 0.25 the maximum flow for the unit (339.3 MGD  -  provided in study), or 85 MGD.
EPRI 2007
Dunkirk
Screenhouse #1, including Units 1 and 2
92.2 MGD
Modifications were made to one of three existing screens.  No information provided on unit operation during study; assume flow through the test screen at maximum capacity.  92.2 MGD specified as prototype study screen capacity.
Beak Consultants, Inc., 2000 (DCN 5-4327)
Huntley
Units 67 and 68
82.8 MGD
All (4 existing) screens replaced at Units 67 and 68 with 5 Ristroph-types screens.  No information provided on unit operation during study; assume flow through the test screen at maximum capacity.  82.8 MGD specified as prototype study screen capacity.
Beak Consultants, Inc., 2000 (DCN 5-4325)
Salem
Unit 1
(1995 study)
266.4 MGD


No information provided on unit operation during study; assume flow through the test screen at maximum capacity.  266.4 MGD specified as Unit 1 design flow rate; 1995 study looked only at performance of Unit 1 screens. 
Ronafalvy, Cheesman, and Matejek, 2000 (DCN 5-4333)

Units 1 and 2
(1997-1998 study)
532.8 MGD
No information provided on unit operation during study; assume flow through the test screen at maximum capacity.  266.4 MGD specified as flow rate at each unit; 1997-1998 study looked at performance of screens at both Unit 1 and Unit 2 for a total DIF of 532.8 MGD.
Ronafalvy, Cheesman, and Matejek, 2000 (DCN 5-4333)



