MEMORANDUM

Tetra Tech, Inc.

10306 Eaton Place, Suite 340

Fairfax, VA 22030

phone 703-385-6000

fax 703-385-6007

TO: Paul Shriner and Lisa Biddle, EPA

FROM: John Sunda, Tetra Tech

DATE: June 21, 2012

SUBJECT: Review of EPA Estimates for Traveling Screen Capital Costs

This memo provides a comparison of reported capital costs for replacement of traveling 

screens against estimated costs developed with the EPA cost technology modules that are 

incorporated into the cost tool.

1

 During EPA’s 2009 visits to several power plants in 

EPA Region VII, EPA obtained reported total capital costs for the entire replacement of 

traveling screens at intakes at the Cooper nuclear power plant and the Labadie coal-fired 

power plant. Both plants withdraw water from the Missouri River, which carries a high 

amount of sand and sediment resulting in a high degree of wear and tear on the traveling 

screens. In the case of Cooper, the installation involved the conversion from single-entry

single-exit (through flow) traveling screens to double-entry single-exit (dual flow) 

traveling screens. This conversion was performed to help reduce the frequency of 

condenser backwash and cleaning maintenance that resulted from excessive debris 

carryover on the through flow traveling screens. The construction company that 

designed, built and delivered the dual flow traveling screens stated in a scope of work 

that “these screens were the first travelling screens designed to both minimize the 

owners’ downtime, and also have the ability to minimize damage to both juvenile and 

adult fish” (Rand Construction 2006). EPA did not actually visit this site and it is not 

clear to what extent these screens include Ristroph-type features but it is apparent from 

the description that some features may be included. The new traveling screens at Labadie 

did not include Ristroph features but the purchased screens were described as being 

designed to allow for an easy retrofit to incorporate Ristroph modifications.

In order to compare the costs of these projects to the EPA estimates, an estimate of the 

relative costs of conventional and modified Ristroph screens is required. A traveling 

screen vendor was contacted and reported that the increase in cost between a 

 

1 The cost tool, including all referenced cost modules, is discussed in detail in Chapter 8 of the Technical 

Development Document (TDD) (DCN 12-0003).
conventional traveling screen and a modified Ristroph traveling screen of the same 

dimensions and mesh size would be around 24% to 26% for screens where the spray

wash and debris return on the original screen are on the downstream (descending) side of 

the screen. The increase would be around 30% for a screen with the original debris return 

on the upstream (ascending) side due to the need for a taller screen (Gathright 2012). 

Approximately 30% to 45% of existing traveling screens have the debris return on the 

upstream side.

Most facilities do not account for traveling screen O&M costs separately, so data for an

O&M cost comparison is not available. Table 1 below summarizes pertinent intake 

design and cost data provided for the Labadie and Cooper facilities.

Table 1

Intake Design and Cost Data Provided by Each Facility

Plant

Design 

Flow

(gpm)

Number 

of 

Screens

Screen 

Width

(ft)

Screen Type Capital 

Cost

Labadie, MO 856,250 8 10

3/8 inch Throughflow Traveling 

Screen

$2,800,000

Cooper 

Nuclear, NE 669,444 9 10

3/8 inch Dual 

Flow Traveling 

Screen

$6,000,000

gpm – gallons per minute

ft – feet

In order to estimate comparable total capital costs using the EPA cost methodology, the 

total screen width and screen well depth must be estimated. Screen well depth was not 

provided but at two other plants visited by EPA on the Missouri River (North Omaha and 

Nebraska City), traveling screen design schematics were provided that indicated the 

screen well depths at these two plants ranged from 46 feet (ft) to 49 ft and screen widths 

were 10 ft. Thus, the 50 ft screen well depth option in EPA’s cost methodology is a good 

fit for comparable cost estimation. For the Cooper facility, 3/8 inch mesh dual flow 

traveling screens replaced existing through-flow screens, which is comparable to the 

technology in Cost Module 11. The Labadie plant reported they installed 3/8 inch 

standard through-flow traveling screens, which is comparable to the technology in Cost 

Module 1. 

As documented in the TDD for the final rule, a review of the cost data suggests that the 

proposal cost estimates for traveling screens may represent easier retrofit situations and 

that in some situations there may be additional costs such as electrical/instrumentation 

and instances where modification to the screen house and other infrastructure may be 

necessary. Based on the data provided here and best professional judgement (BPJ), EPA 

concluded that a 20% increase in the traveling screen component would provide a cost 

estimate that is more reflective of the wider range of costs represented by the example 

provided here. As described in the final TDD EPA also increased the cost estimate for the 
fish return components by 100%. Table 2 presents a comparison of the screen 

replacement costs reported by the facilities to the EPA capital cost estimates for the

proposed and final rules.

Table 2

Comparison of Reported Cost of Traveling Screen Replacement to Comparable 

EPA Cost Module Capital Cost Estimate and Cost Module Design Basis

Plant

Reported

Screen 

Replacement 

Capital 

Cost1

EPA Estimated Capital 

Cost Estimate (2009 

Dollars)

EPA Cost Estimate Basis2

Proposal Final3 Type of 

Plant

Cost 

Module

Total 

Screen 

Width (ft)

Regional 

Factor4

Labadie, MO $2,800,000 $3,300,000 $4,100,000 Nonnuclear 1 80 1.054

Cooper 

Nuclear, NE $6,000,000 $6,300,000 $7,900,000 Nuclear 11 90 0.847

1 Costs do not include fish return, added spray water pumps, or certain Ristroph features.

2

Screen well depth is assumed to be 50 ft and costs are adjusted to February 2009 

Dollars. 

3 Traveling screen upgrade capital cost estimates were increased from proposal including 

a 20% increase for the screens and a 100% increase for the fish return components. 

4 Regional cost factors that account for regional variations from the national average in 

construction and materials costs were developed from ENR data for Phase II. 

The EPA proposed rule capital cost estimates were very close in value to the reported

estimates but the EPA costs included the full suite of modified Ristroph features plus the 

fish return spray pumps piping and fish return flume. This, along with several public 

comments to the proposed rule stating that Ristroph traveling screen costs were 

underestimated, prompted a re-evaluation of traveling screen costs and the final rule 

revisions.

The EPA final rule cost estimates are 30% higher for the Cooper Nuclear plant where 

there are indications that some Ristroph features may already be present. Thus, this extra 

30% should be sufficient to cover the spray water pumps and fish return trough not 

included in the reported facility costs. 

The EPA final rule cost estimates for the Labadie plant are 46% higher than the reported

facility cost for screen replacement. Therefore, the EPA cost estimate is clearly sufficient 

to include the cost of the estimated 24% to 30% for Ristroph features plus additional

money to cover the spray water pumps and fish return flume. As indicated in the site visit 

report for Labadie, facility personnel estimated that an upgrade of the existing screens to 

modified Ristroph traveling screens would have cost $4 million which is nearly equal to 

the revised final rule estimate (DCN 10-6532).
These examples confirm that the BPJ adjustment factors of 20% for traveling screens and 

100% for fish returns used to revise the capital cost estimates for traveling screens used 

in the final rule are representative of reported facility costs.

References

Rand Construction Co. Dual Flow Conversion. Cooper Nuclear Station. Brownsville, NE. 

Scope of Work. Completed January 2006. Accessed May 24, 2012 website: 

http://www.randsc.com/industrial_dual.html#

Gathright, Trent, Ovivo. Telephone Contact Report with John Sunda, Tetra Tech. 

Regarding relative capital costs of conventional and modified Ristroph traveling screens. 

May 24, 2012. DCN 12-6653.

Site Visit Report. Labadie Power Plant. DCN 10-6532.

Site Description Report. Cooper Nuclear Power Plant. DCN 10-6522.