Digesters at La Crosse Provide some incredibly interesting - - PowerPoint PPT Presentation

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May 31, 2023 152 likes •494 views

Replace or Rehab Anaerobic Digesters at La Crosse Provide some incredibly interesting information describing the La Crosse wastewater treatment plant. Provide historical information related to the Citys experience with other rehab

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Replace or Rehab Anaerobic Digesters at La Crosse

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 Provide some incredibly interesting information describing the La Crosse wastewater treatment plant.  Provide historical information related to the City’s experience with other rehab projects at its WWTP.  Provide details of the existing digestion system at the WWTP and the decision-making process related to rehabilitation instead of replacement.  Look at the details and challenges of the process to rehabilitate the first digester.  Summarize costs for the first digester rehabilitation project.  What did we learn for the next project(s)?  Include LOTS of pictures!!

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 Impress anyone with an especially innovative use of PowerPoint (or any other) technology, and/or  Impress anyone with the presentation capabilities of the presenters!

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 West coast of Wisconsin; approx. City population of 52,000.  WWTP……

 20 MGD facility  Regional wastewater plant - currently receives flow from five areas

utside corporate limits; approx. population served 85,000 – 90,000.

 Anaerobic Digestion System

 Four “vintage” digesters: Newest 1953….Oldest 1936 (original)

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 2002 – Three Primary Clarifiers

 All steel  Concrete tank restoration (epoxy injection)  Handrail  Project costs:

Rehabilitation - $ 220,300
Design, Engineering & Project Management - $100,000

2004 – Four Final and Two Rectangular Primary Clarifiers

 All steel  Concrete tank restoration (epoxy injection)  Handrail  Project costs:

Rehabilitation - $ 829,000
Design, Engineering & Project Management - $100,000

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2011 – Two Gravity Thickeners

 All steel  One drive mechanism  Concrete tank restoration (epoxy injection)  Handrail  Project costs:

Rehabilitation - $ 220,100
Design, Engineering & Project Management - $100,000

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 One 74’ diameter spiral-guided cover

 Original cover installed in 1953; inspected in last five years as part of digester cleaning  Remove cover from tank  Structural and steel replacement as required  Complete sandblast and re-paint  Re-installation of cover into tank & start-up  Project costs:

Rehabilitation - $ 435,000
Design, Engineering & Project Management - $100,000

 Estimated cost to replace - $1.3 million

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 Project costs:

Rehabilitation - $ 435,000
Design, Engineering & Project Management - $100,000

 Estimated cost to replace - $1.25 million

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 Inspection is critical first step.  Capacity issues?  Philosophy, i.e., replace just because it’s old…..??  Design has to assume some surprises along the way.  On-site inspection during project!!!!!  Resulting Value – La Crosse experience has been that rehabilitation can be a very cost-effective alternative to replacement.

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 Wastewater supervisors and staff  City Engineering Department  Process Equipment Repair Services

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