After 15 years of continuously supporting the cooling of campus buildings, Cornell’s Lake Source Cooling (LSC) intake pipe and screen need a cleaning. Zebra and quagga mussels have partially covered the pipe surface, lowering water flow into the plant.
Cornell has hired Makai Ocean Engineering to provide engineering support in defining the work, and specialty marine contractor Global Diving and Salvage, Inc., to carry out the cleaning, which is scheduled for Oct. 8-19, though poor weather may extend the operation.
The pipe will be cleaned mechanically, since this method is the most benign and causes no adverse environmental impacts. Three foam brushes will be pushed through by reverse-flowing water from the plant into the lake. The brushes will float to the top for retrieval.
To get the job done, a 75-by-45-foot floating platform will be anchored above the intake pipe, which is 250 feet below the lake’s surface and about a mile southeast of the Ithaca Yacht Club. The work platform will house toolboxes, a generator, air compressor, diving equipment and a crane to lift the pipe’s intake screen to the surface for cleaning.
The New York State Department of Environmental Conservation has approved the operation.
“The cleaning of the intake at Lake Source Cooling was fully investigated and planned as part of creating and permitting the project” in 1998, before LSC came online in 2000, said Lanny Joyce, Cornell’s director of utilities and energy management. “This cleaning operation is a normal part of controlling the buildup of the invasive exotic fresh water mussels that are now covering the bottoms of the Great Lakes and Finger Lakes. The cleaning will return our intake to normal pressure drop and ensure continued operation with minimum energy use for years to come.”
“Global Diving and Salvage is one of the best marine contractors worldwide and is well-equipped to perform this work,” said Joshua LaPenna, Cornell’s Central Energy Plant manager.
LSC cools Cornell and Ithaca High School buildings using the cold, deep waters of Cayuga Lake instead of refrigeration-based water chillers. Since its inception, LSC has won seven major state, national and international awards, including the 2002 New York State Department of Environmental Conservation Governor’s Award for Pollution Prevention.
“Lake Source Cooling has worked exceptionally well since 2000 and is one of our most significant investments in reducing our environmental impact,” said Joyce, noting that the project reduces total campus electricity use by more than 10 percent while cutting carbon dioxide and other greenhouse gas emissions. The electricity costs to cool Cornell and Ithaca High School have been reduced by 85 percent, he said. The start of LSC in 2000 kicked off the Energy Conservation Initiative at Cornell, which seeks to reduce climate gas emissions from energy use in a cost-effective manner.
“Since 2000 and the start of Lake Source Cooling, Cornell has invested over $43 million in additional building energy efficiency projects, creating enough savings to keep total campus energy use flat while campus indoor square footage has expanded in total by about 20 percent,” Joyce said.
In 1998, an environmental analysis of the effects of returning warmer water to the lake found impacts to be well within the natural variability of the lake. That study was followed with extensive lake monitoring and the Cayuga Lake Modeling Project. The goal of that project, which is due for completion in 2016, is to build a computational water quality model of Cayuga Lake and its watershed, providing a better understanding of where phosphorus comes from and how it affects the lake ecosystem.
The intake pipe cleaning comes after the first week of October, when boaters are starting to remove their boats from the lake for winter. The platform will be fitted with nightlights and signs.
Cornell is paying all costs for the cleaning and pays for all operations, maintenance and regulatory compliance activities related to LSC.