USEPA / AmerenUE

Meramec Power Plant

Intake Structure Site Visit
March 4, 2009 USEPA Intake 

Structure Site Visit

Meramec Power Plant General No

 4 steam-generating 

units: ~835MW total

 Began Operation: 

1953

 Capacity Factor: 

76.3% (2008)
March 4, 2009 USEPA Intake 

Structure Site Visit

Meramec Power Plant

Mississippi River Overview

 2nd longest river in North America

 Length: 2,320 miles Drainage area: ~41% of North America

(combined Mississippi and Missouri River)

 Channelized from Alton IL to Gulf of Mexico High silt content

 288 mg/L TSS (average 2007-2008) 1,140 mg/L TSS (max, May 2007) Inlet condenser erosion led to SS tube retrofit

 Historic high flow events:

 1993: 1,070,000 cfs (USGS St. Louis gauge) 2008: 716,000 cfs (USGS St. Louis gauge)

 Average flow: 171,400 cfs

USGS St. Louis, 2000-2007
March 4, 2009 USEPA Intake 

Structure Site Visit

Meramec Power Plant

Intake Structure Design

 Shoreline intake Average 2007-2008 Mississippi wa

withdrawal ~382,000gpm (851cfs)

 Design flow = 468,400gpm (1,044 Eight intake bays/pumps
March 4, 2009 USEPA Intake 

Structure Site Visit

Meramec Power Plant

Intake Structure Drawing
March 4, 2009 USEPA Intake 

Structure Site Visit

Meramec Power Plant

Traveling Screen & Bar Rack Des

 Bar rack on 3” center (2008-2009)

 Original 8 X13 ft, 3inch spacing

 Traveling screen replacement (1999-2004)

 Original screens: 1950’s drives/technology/frame integri Dual-flow design, decreased debris carryover to conden 3/8” mesh screens

 Screen approach velocity

 1.2 fps (Units 1/2) 1.3 fps (Units 3/4)

 Screen wash discharge to flume Screen rotation

 Determined by ∆P

 “Normal” (15”) “Fast” (3ft) Screens designed for 5ft max DP
March 4, 2009 USEPA Intake 

Structure Site Visit

Meramec Power Plant

Intake Bay Drawing
March 4, 2009 USEPA Intake 

Structure Site Visit

Meramec Power Plant

Intake Structure Maintenanc

 Scheduled routine visual inspectio Replace repair damaged screens Continuous operation and monito

during severe debris loading

 Backwash bays
March 4, 2009 USEPA Intake 

Structure Site Visit

Meramec Power Plant

Intake Structure Debris Impact

 Historic debris issues Screens

 Leaves during Spring and Fall Traveling screen damage

 4-5 baskets damaged with each major debris e

 Bar rack 

 Logs and other Debris Backwash bays

 Events cause load reductions or outage
March 4, 2009 USEPA Intake 

Structure Site Visit

Production losses due to Scree

 ECR MR 2006-01 High screen differential cau

backpressure and load drop. Screen damage

 ECR MR 2003-0098 All units experiencing hig

pressure due to leaves at the caisson. Unit 3 high backpressure.

 ECR MR-2002-0094 Unit 4 tripped due to hig

condenser pressure. Failed screens caused dbe carried into condensers 

 ECR MR-2002-0099 High differential across r

screens caused cavitation of circulating water Unit trip. 

 ECR MR 2000-46 Screen failed allowing trash 

carried into plant. Unit 4 taken off
March 4, 2009 USEPA Intake 

Structure Site Visit

Meramec Power Plant

Traveling Screen Matted Debri
March 4, 2009 USEPA Intake 

Structure Site Visit

Meramec Power Plant

Intake Structure Upgrade Proje

 Bar rack replacement (2009)

 Rake to remove debris 

 Traveling screen replacement (199

2004)

 Dual-flow design Decreased debris carryover
March 4, 2009 USEPA Intake 

Structure Site Visit

Meramec Power Plant

Intake Structure Bar Rack Upgra
March 4, 2009 USEPA Intake 

Structure Site Visit

Meramec Power Plant

Intake Impingement Mortality Stu

 Conducted in 2005-2006 No T&E species ~95.8% shad & drum (2005-2006) ~95.9% shad/drum/carp (2005-2006)
March 4, 2009 USEPA Intake 

Structure Site Visit

Meramec Power Plant

Intake Draft Technology Assessm

 Conducted prior to remand of Phase II Rule Fine mesh screens not evaluated Dual-flow Ristroph screens with expanded int

 1.0fps screen velocity, 3/8” screen mesh Four new bays with pumps New fish return system $84M (2002 estimated)

 Ristroph screens with reduced intake flow

 1.0fps screen velocity, 3/8” screen mesh 20% flow reduction New fish return system 73.3M (2002 estimated)
March 4, 2009 USEPA Intake 

Structure Site Visit

Meramec Power Plant

Intake Draft Technology Assessment 

 Bar rack barrier

 1” spacing located on intake structure face 0.5fps approach velocity Trash rake system $7.6M (2002 estimated)

 Wide-slot Cylindrical Wedgewire screens

 Bulkhead mounting (19’ from intake structure face)

 0.5fps approach velocity 20 screens (each 4.5’Dx15’L) Air backwash system (no provisions for biofouling)

 $76.5M (2002 estimated)

 Fixed screen with bar rack

 1⁄2” mesh on bar rack barrier 0.5fps approach velocity Trash rake system $9.2M (2002 estimated)
March 4, 2009 USEPA Intake 

Structure Site Visit

Meramec Power Plant

Fine Mesh Screen Concerns

 Debris loading with fine mesh screens

 Large freshwater inland river Non-point source runoff Entrainment survivability with high debris

 Icing and fine mesh screens Intake expansion potential Potential reinforcement of structure and scree Unknown impacts on plant reliability

 Debris Low river elevation operation

 Viability of national standard – additional rese

needed

 Site-specificity: large freshwater river & lake
March 4, 2009 USEPA Intake 

Structure Site Visit

Meramec Power Plant

 Comments and questions