1 Site Visit Report Meramec Plant 8200 Fine Road St. Louis , MO 63 219 March 4 , 2009 1.0 Background and Objectives The Environmental Protection Agency (EPA) is in the process of developing 316(b) cooling water intake structure requirements that reflect the b est 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 manufacturers to better understand the cooling wat er intake structure (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 coolin g water use and specific issues or technologies that can affect 316(b) compliance. Meramec was selected for a site visit due to its location on a large freshwater river

. 2.0 Facility Description Meramec is located on a 264 acre site about 20 miles south of St. L ouis on the Mississippi River. The facility began operations in 1953 and employ s roughly 230 people. Meramec is owned and operated b y Ameren. The facility ’s NPDES permit ( MO0000361 ) expired May 18, 2005. 1 3.0 Electricity Generation and Transmission M eramec consists of 4 coal

- fired 2 generating units 3 and has a total generating capacity of 835 MW. The units were commissioned between 1953 and 1961 and range in size from 125 MW to 300 MW. The facility ’s capacit y utilization rate (CUR) is approximately

7 6%. Scheduled major outages at each unit occur every 6 y ears and vary in length dependin g on the tasks to be performed. The transmission sy stem is owned by Ameren but is operated by a different business unit.

1 Ameren submitted its renewal application i n a timely manner and aw aits the renewal of its permit. 2 The facility’s coal comes via rail from the Powder River Basin in Wyoming. 3 Units 1 and 2 are identical.2

4.0 Cooling Water System and Intake Structure M eramec has one CWI S that withdraws once

- through cooling water from the Mississippi River. The shoreline CWI S has a design intake flow (DIF) of 674 million gallons per day

(mgd) 4 and an average actual intake flow (AIF) of 550 mgd. The CWI S has a common tr ash rack 5 and 8 intake bay s (2 per unit), each with a single circulating pump and coarse mesh (3/8” mesh) dual flow traveling screen. 6 The screens are rotate d every 8 hours and are cleaned with a high pressure spray

wash. The screens rotate slowl y with a head differential across the screens of 18 inches and switch to a faster speed when the differential reaches three feet ; during high debris loading periods, the screens often operate continuously . The debris return is a trough in the deck of the screenho use and discharges at the downstream end (approximately 20 feet above the water line on the day of the site visit). The design intake velocity of the CWIS at Units 1 and 2 is 1.2 feet per second (fps) and 1.3 fps at Units 3 and 4. Routine maintenance inc ludes visual inspections , repair or replacement of screen parts (about once per month) , and a backwashing of sediment in the intake bay

. Meramec discharges heated effluent to the river approximately 2 00 feet downstream of the CWI S. In the 1980s, Meramec added flow straighteners inside the CWI S to improve the flow of water through the screens and into the pumps; previously , there were issues with eddies within the pump well, occasionally leading to the intake of air. 5.0 Impingement and Entrainment Informatio n Ameren conducted impingement studies at all of its Phase II facilities in 2005 and 2006. During the sampling period, Meramec conducted 24 hour impingement sampling every

other week for a ye ar for a total of 26 sampling events. Approximately

96% of th e fish collected at Meramec were shad and drum. The sampling estimated an annual impingement total of approximately 166,000 fish including moribund fish. 6.0 Cooling Tower Feasibility Meramec has not considered retrofitting to a closed

- cycle recirculating s ys tem (CCRS). Facility

representatives noted that the surrounding area has become much more developed over time, leading to potential permitting issues. They

4 The pumps for Units 1 and 2 have a capacity of 64.8 mgd each, Unit 3 a capacity of 86.4 mg d, and Unit 4 a capacity of 115.2 mgd. 5 The facility is in the process of replacing its bar rack; the new design will have additional design features to improve debris handling, much like the one installed at Labadie. The face of the trash rack will be f lat and flush with the front of the CWIS and a mechanical trash rake will also be installed. 6 Meramec replaced all of its traveling screens between 1999 and 2004; dual flow screens were selected to reduce debris carryover.3 noted the facilit y is surrounded by a steep bluff to the north, a wastewater treatment plant, th e Meramec River, as well as neighboring homes and a golf course. 7.0 Debris Handling Meramec has had significant problems with debris in the past (especially with spring and fall leaf loads) , including 5 unit shutdowns since 2000

. 7 Facility representatives noted that a major debris event ty pically leads to 4

- 5 screen panels being damaged. At the facility , the Mississippi River has an average flow of 171,400 cfs (110,779 mgd), with average and maximum silt levels in 2007/2008 of 288 mg/L total suspended soli ds (TSS) and 1,140 mg/L TSS, respectivel y. 8.0 Repowering/Future Uses Currently , Meramec has no plans for re

- powering or upgrades. 9.0 Cooling Ponds There are no cooling ponds on site. 10.0 Ownership Meramec is owned b y Ameren, an investor

- owned compan y. 11.0 316(a) Facilit y representatives stated that Meramec currently has no problems meeting its thermal discharge requirements. However, they noted any

316(b) solutions that involve flow reduction may cause an increase in the discharge temperature (in addition to th e lost generation) which could lead to exceedances in its 316(a) water qualit y limits

. 12.0 Ash Handling Fly ash is handled dry

and facility

representatives noted that virtually all of the fly ash is sold for beneficial uses. Approximately 5% of the bottom a sh is sold; the remainder is sluiced to an on

- site ash pond. A large volume of bottom ash was used in reconstructing the embankment at its Taum Sauk pumped storage facility

. Ameren has an internal team that conducts inspections of all earthen dams and si milar structures. Due to a dam failure at the Taum Sauk facility in 2005, Ameren instituted rigorous inspections at all facilities. Facility representatives

7 Unit 3 was the most frequently affected unit, despite its position in the center of the screenhouse.4 noted that Ameren’s inspections are more stringent than those conducted b y state agencies. 13.0 Air E missions Controls EPA did not collect any

information on air emissions controls. 14.0 Additional Information Facilit y representatives stated that they had begun to evaluate intake technologies for compliance with the 2004 Phase II rule. One approach was to adapt the existing dual flow screens with Ristroph buckets, dedicated fish return, and to expand the CWI S for an estimated cost of $84 million ($2004). Other options included a Ristroph screen and dedicated fish return paired with a 20% flow reduction 8 fo r an estimated cost of $73 million; bar rack barriers with 1” spacing with a reduced through screen velocit y of 0.5 fps for an estimated cost of $7.6 million; coarse mesh wedgewire screens 9 for an estimated cost of $76 million; and a fixed screen with a bar rack fitted with 1⁄2” mesh for an estimated cost of $9.2 million. Facilit y representative reiterated concerns over fine mesh screens, as well as other aspects of the rulemaking. Please refer to Section 14.0 of the site visit report for Labadie for a dis cussion of these issues. Meramec has two coal piles onsite . This second pile was intended to be dual

purpose: one, as overflow storage for Meramec’s use (or to re

- sell to other plants along the Mississippi) and two, to provide a way point for loading barg e transported coal onto trains for transport to inland facilities (or vice versa)

. However, the coal un loading dock was decommissioned in 2002; the dock for offloading coal onto a barge is still functional.

Attachments Attachment A List of Attendees Attachment B Aerial Photos Attachment C Site Visit Photos Attachment D Ameren PowerPoint Presentation (March 4, 2009)

8 A flow reduction of 20% could be achieved by throttling back generation; a bulkhead wall would be constructed in front of the existing intake and 20 w edgewire screens would be install ed. 9 A bulkhead w all would be constructed in front of the existing intake and 20 w edge wire screens would be installed.5

Attachment A -- List of Attendees Paul Shriner, EPA Headquarters Jan Matuszko, EPA Headquarters Jamie Hurley , EPA Headquarters John Dunn, EPA Region VII Mark Matthews, EPA Region VII Kelly Meadows, Tetra Tech Steve Whitworth, Ameren Mark L itzinger, Ameren Nancy Morgan, Ameren Mike Smallwood, Ameren Mike Bollinger, Ameren Kirk Schweiss, Ameren Tim L afser, Ameren Keith My ers, Ameren John Beck, Ameren6 Attachment B -- Aerial Photos7

Attachment C

— Site Visit Photos Please see attached materials. Attachment D

—

Ameren PowerPoint Presentation (March 4, 2009) Please see attached materials.