Site Visit Report

	Meramec Plant

	8200 Fine Road

	St. Louis, MO 63219

March 4, 2009

Background and Objectives

The Environmental Protection Agency (EPA) is in the process of
developing 316(b) cooling water intake structure 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 manufacturers to better understand the cooling water
intake structure (CWIS) technologies in use at facilities, including the
site-specific characteristics of each facility and how these affect the
selection and performance of CWIS technologies.  EPA is also visiting
facilities to better understand cooling 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.

Facility Description

Meramec is located on a 264 acre site about 20 miles south of St. Louis
on the Mississippi River.  The facility began operations in 1953 and
employs roughly 230 people.

Meramec is owned and operated by Ameren.  The facility’s NPDES permit
(MO0000361) expired May 18, 2005.

Electricity Generation and Transmission

Meramec consists of 4 coal-fired generating units 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
capacity utilization rate (CUR) is approximately 76%.

Scheduled major outages at each unit occur every 6 years and vary in
length depending on the tasks to be performed.

The transmission system is owned by Ameren but is operated by a
different business unit.

Cooling Water System and Intake Structure

Meramec has one CWIS that withdraws once-through cooling water from the
Mississippi River.  The shoreline CWIS has a design intake flow (DIF) of
674 million gallons per day (mgd) and an average actual intake flow
(AIF) of 550 mgd.  The CWIS has a common trash rack and 8 intake bays (2
per unit), each with a single circulating pump and coarse mesh (3/8”
mesh) dual flow traveling screen.  The screens are rotated every 8 hours
and are cleaned with a high pressure spray wash.  The screens rotate
slowly 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
screenhouse 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 includes 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 200 feet
downstream of the CWIS.

In the 1980s, Meramec added flow straighteners inside the CWIS 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.

Impingement and Entrainment Information

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 year for a total of 26
sampling events.   Approximately 96% of the fish collected at Meramec
were shad and drum.  The sampling estimated an annual impingement total
of approximately 166,000 fish including moribund fish.

Cooling Tower Feasibility

Meramec has not considered retrofitting to a closed-cycle recirculating
system (CCRS).  Facility representatives noted that the surrounding area
has become much more developed over time, leading to potential
permitting issues.  They noted the facility is surrounded by a steep
bluff to the north, a wastewater treatment plant, the Meramec River, as
well as neighboring homes and a golf course.

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.
 Facility representatives noted that a major debris event typically
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 solids (TSS) and 1,140 mg/L TSS, respectively.

Repowering/Future Uses

Currently, Meramec has no plans for re-powering or upgrades.

Cooling Ponds

	

There are no cooling ponds on site.

Ownership

Meramec is owned by Ameren, an investor-owned company.

316(a)

Facility 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 the lost generation) which
could lead to exceedances in its 316(a) water quality limits.

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 ash 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 similar structures.  Due to a dam failure at the Taum Sauk
facility in 2005, Ameren instituted rigorous inspections at all
facilities.  Facility representatives noted that Ameren’s inspections
are more stringent than those conducted by state agencies.

Air Emissions Controls

EPA did not collect any information on air emissions controls.

Additional Information

Facility 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 CWIS for an estimated cost of
$84 million ($2004).  Other options included a Ristroph screen and
dedicated fish return paired with a 20% flow reduction for an estimated
cost of $73 million; bar rack barriers with 1” spacing with a reduced
through screen velocity of 0.5 fps for an estimated cost of $7.6
million; coarse mesh wedgewire screens for an estimated cost of $76
million; and a fixed screen with a bar rack fitted with ½” mesh for
an estimated cost of $9.2 million. 

Facility 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 discussion 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
waypoint for loading barge-transported coal onto trains for transport to
inland facilities (or vice versa).  However, the coal unloading 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)

		

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 Litzinger, Ameren

Nancy Morgan, Ameren

Mike Smallwood, Ameren

Mike Bollinger, Ameren

Kirk Schweiss, Ameren

Tim Lafser, Ameren

Keith Myers, Ameren

John Beck, Ameren

Attachment B--Aerial Photos



Attachment C— Site Visit Photos

Please see attached materials.

Attachment D—Ameren PowerPoint Presentation (March 4, 2009)

Please see attached materials.

 Ameren submitted its renewal application in a timely manner and awaits
the renewal of its permit.

 The facility’s coal comes via rail from the Powder River Basin in
Wyoming.

 Units 1 and 2 are identical.

 The pumps for Units 1 and 2 have a capacity of 64.8 mgd each, Unit 3 a
capacity of 86.4 mgd, and Unit 4 a capacity of 115.2 mgd.

 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 flat and flush with the front of the CWIS and a mechanical trash rake
will also be installed.

 Meramec replaced all of its traveling screens between 1999 and 2004;
dual flow screens were selected to reduce debris carryover.

 Unit 3 was the most frequently affected unit, despite its position in
the center of the screenhouse.

 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 wedgewire screens would be installed.

 A bulkhead wall would be constructed in front of the existing intake
and 20 wedgewire screens would be installed.

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