1 Site Visit Report Walter Scott, Jr. Energy

Center 72 15 Navajo Road Council Bluffs, IA 51501 March 2 , 2009 1.0 Background and Objectives The Environmental Protection Agency (EPA) is in the process of developing 316(b) cooling water intake structure (CWI S) requirements that reflect the best technology

available (BTA) for minimizing adverse environmental impact for all existing power plants and manufacturing facilities. As part of this process, EPA staff is visiting electric generators and manufacturer s to better understand the CWI S technologies in use at facilities, including the site
- specific characteristics of each facility

and how these affect the selection and performance of CWI S technologies. EPA is also visiting facilities to better understand c ooling water use and specific issues or technologies that can affect 316(b) compliance. Walter Scott, Jr. Energy

Center (WSEC) 1 was selected for a site visit due to its location on a large freshwater river
. 2.0 Facility Description WSEC is located approximately four miles south of downtown Council Bluffs, Io wa. The facilit y began operations in 1954 . Units 1, 2, and 3 w ithdraw once through cooling water from the Missouri River , and Unit 4 withdraws closed
cycle cooling tower make
- up water from four lateral alluvial wells
. WSEC is regulated b y NPDES permit IA 0004308 (which expired February 26, 2008 2 ) and is owned by

MidAmerican Energy Company . The facility employ s approximately 220 people . T he facility and surrounding land encompasses approximately

1,195 acres
. 3 3.0 Electricity Generation and Transmission WSEC consists of four coal
- fueled generating units with a total generating capacity of 1623 MW
. 4 The facility ’s low sulfur coal comes via rail from the Powder River Basin in Wyoming; 128 car trains arrive approximately every 18 hours and the facility

uses about seven million tons of coal per ye ar. The
1 The facility has historically been referred to as the Council Bluffs Energy Center. 2 All NPDES permits for MidAmerican facilities are currently expired; renewal applications were timely submitted but await approval by the permitting authority. Neal South wa s the first MidAmerican facility to receive a renewed permit effective March 31, 2 009. 3 Facility representatives noted that approximately 304 acres of the site is in use surface impoundments. Additionally, adjacent farmland was purchased to provide a buffer from surrounding lands. 4 Unit 1 has a capacity of 45 MW and began operations in 1954; Unit 2 is 88 MW and began in 1958; Unit 3 is 690 MW and began in 1979; Unit 4 is 800 MW and began in 2007.2 facility ’s capacit y utilization rate (CUR) is approximately 80% ; all four generating units operate as baseload units. The transmission sy stem is owned by MidAmerican Energy

Company but is operated b y a different business unit. 4.0 Cooling Water System and Intake Structure WSEC has two CWI Ss that withdraw cooling water from the shoreline of the Missouri River. Units 1 and 2 share one CWI S; it has four traveling screens and four circulating water pumps. Unit 3’s CWI S has four screens and four circulating water pumps. The design intake flow (DIF) for the facility is 662 million gallons per day

(mgd) and the aver age actual intake flow (AIF) for 2009 was 470 mgd. Units 1
- 3 utilize once
- through cooling and Unit 4 uses a closed
cycle cooling s ys tem ( see Section 6.0 below ). 5 Units 1
- 3 employ

coarse mesh traveling screens. 6 Units 1 and 2 have standard debris return troughs that return fish and debris to the river; Unit 3 has a separate fish spray wash and trough that combines with the debris return before being discharged to the river. The screens automatically rotate every 15
- 20 minutes and are cleaned with a high pressure spray wash; during high debris loading periods, the screens often operate continuously
. The design through
- screen velocit y ranges from 1.7 to 1.9 feet per second (fps) at Units 1
- 2 and approximately three fps at Unit 3. Scheduled four to six wee k major maintenance outages are taken on each unit as needed (t ypically once every 4 year s ) . For Units 1
- 3, one traveling screen and circulating pump are refurbished each year. Maintenance can be scheduled during the winter, when all of the screens and pumps are not required for normal operations. 5.0 Impingement and Entrainment Information WSE C is currently

working to finalize a 2007 impingement study ; this study will also include an evaluation of intake technologies and compliance approaches. 6.0 Cooling Tower Feasibility Facility representatives stated that close
- cycle cooling was not reasonabl y feasible for WSEC Units 1
- 3 . They noted a number of potential problems: space

5 Makeup water for the towers is drawn from groundwater wells. 6 Travelling screens for Units 1, 2, and 3 are 3/8
- inch mesh.3 constraints , a loss of generating efficie ncy , high costs, 7 and icing on the transmission lines. 8 The cooling tower for Unit 4 (a 22
- cell mechanical draft tower with two back
- to back rows of 11 cells) was not designed with plume abatement 9 and ty pically cycles water 6
- 8 times before blowdown. 10 The towers use a standard mix of biocide s — 1 2.5% sodium hy pochlorite and bisulfate at the basin discharge. The sy stem loses approximate ly two percent of the circulating flow to evaporation. 7.0 Debris Handling WSEC has historically

had issues with debris in the spring, when leaves, sticks, and eroded low
- grade coal (found in the surrounding soil) are swept up in the rising waters. Because a major outage occurred on Unit 3 as a result of debris, the facility installed a 5mm Tapproge debris filter on Unit 3
. According to facility

representatives, ice is not a significant problem at WSEC
. The facility

is capable of recirculating warm water to the CWI S to address the issue. However, at the time of the site visit, Unit 1 had been taken offline due to ice blocking the intake and causing condenser vacuum problems. The condenser also experiences some scaling and calcium deposits, but this issue is manageable; a firm is hired once per ye ar to remove these deposits. 8.0 Repowering/Future Uses WSEC’s Unit 4 began operations in 2007. There are no plans for additional units at the facility at this time
. The facility

also provides steam to a neighboring ethanol manufacturing plant that recentl y began operations. WSEC provides approximately 475,000 pounds of steam per hour from Unit 3, which represents approximately 10% of the main steam flow. 9.0 Cooling Ponds There are no cooling ponds on sit e.

7 A consultant’s report estimated costs for closed
- cycle cooling at $55 million, plus $2
- 3 million per year in operations and maintenance (O&M). 8 The cooling tower for Unit 4 has exhibited problems with icing. At the time of the site visit, icing was clearly visible in the area above the basin and on the structural elements of the tower. 9 Facility representatives noted that the plume can block visibility within the plant boundaries. Additionally, depending on wind conditions, the tower plume can be drawn back into the towers, reducing the overall efficiency. 10 Water hardness (calcium and magnesium) is generally the limiting factor.4

10.0 Ownership The WSEC facility is operated by MidAmerican Energy , an investor
- owned utility
. Units 1 and 2 are 100% owned by MidAmerican Energy

Company , whereas Units 3 and 4 are jointly
- owned units. 11.0 316(a) Facility representatives stated that , under the current NPDES permit, WSEC is not subject to any

316(a) limitations
. They expect to complete a thermal plume mixing zone study

later this year. 12.0 Ash Handling Fly ash from Units 1
- 3 is ty

picall y sold for beneficial uses , but is occasionally stored in a lined monofill when market conditions are unfavorable . Bottom ash from Units 1
- 3 is wet sluiced to two onsite impoundments ; facility representatives noted that they

are researching potential markets for the sale of the bo ttom ash. Fly ash and bottom ash from Unit 4 is stored in an onsite lined monofill
. The Arm y Corps of Engineers conducts inspections of the levees surrounding the surface impoundment s and performs an y necessary maintenance. 13.0 Air Emissions Controls WSEC uses low NOx burners on all of its generating units , and overfire air is installed on Units 2
- 4
. Dry scrubber and baghouse sy stems are installed on Units 3 and 4; and a selective cataly tic reduction s ys tem and activated carbon injection sy stem is installe d on Unit 4. Materials provided by the facility

also note that Unit 4 uses a supercritical boiler, increasing efficiency and reducing carbon dioxide emissions by

approximately

15%. There are no firm plans for an y additional air emission control equipment at this time
. Attachments Attachm ent A List of Attendees Attachment B Aerial Photo Attachment C Walter Scott Energy Center Fact Sheet Attachment D Walter Scott Energy Center CWI S Information Attachment E Engineering and Flow Diagrams Attachment F Site Photos Attachment G Proposal for Information Collection5

Attachment A -- List of Attendees Paul Shriner, EPA Headquarters Jan Matuszko, EPA Headquarters Jamie Hurley , EPA Headquarters John Dunn, EPA Region VII Glenn Curtis, EPA Region VII John Bender, Nebraska Department of Environmental Quality Kelly Meadows, Tetra Tech Matt Finnegan, MidAmerican John Lusan , MidAmerican Spencer Moore , MidAmerican David O’Dell, MidAmerican Mark Podan y, MidAmerican Jeff Walters, MidAmerican6

Attachment B
–Aerial Photo Please see DCN 10
- 65 18A accompan yi ng this document Attachment C -- Walter Scott Energy Center Fact Sheet Please see DCN 10
- 6518B accompan yi ng this document Attachment D -- Walter Scott Energy Center CWIS Information Please see DCN 10
- 6518C accompan yi ng this document Attachment E -- Engineering and Flow Diagrams Please see DCN 10
- 6518D accompan yi ng this document Attachment F -- Site Photos Please se e DCN 10
- 6518E accompan yi ng this document Attachment G -- Proposal for Information Collection Please see DCN 10
- 6518F accompan yi ng this document