A Test of the Flow Velocity Enhancement System (FVES) for Deflecting Aquatic Vegetation from the Intake of Genoa Power Station #3, Wisconsin

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This report reviews the results of an evaluation of the Flow Velocity Enhancement System (FVES), a new technology for generating motive water in the water column to deflect downstream drifting aquatic weeds from cooling water intakes. The research was conducted at Dairyland Power’s Genoa Generating Station on the upper Mississippi River in Wisconsin and funded in part by the Electric Power Research Institute (EPRI). Technicians from Alden Laboratory in Holden, MA provided bathometry and flow mapping services.

Background

Blockage of cooling water intake structures (CWIS) by waterborne debris occurs frequently at nuclear and fossil power plants worldwide. Operational impacts include equipment damage, facility de-rates and outages, and plant safety concerns. These impacts can ultimately translate to system reliability problems and declines in plant revenue. The FVES by Natural Solutions of Helena, Montana, induces currents within water bodies to enhance debris movement near CWIS. The FVES is a venturi pump (eductor) that creates a velocity plume extending several hundred feet from the unit (depending on pump size). During initial testing in the Pacific Northwest, the FVES showed a dramatic displacement of floating riverine woody debris away from the eductor. It was theorized that a FVES placed immediately upstream of a river shoreline CWIS would divert surface debris (e.g., logs, sticks, aquatic plants, dead or moribund fish, ice) away from the shore where it would be carried downstream in mid-channel. The intake flow is expected to move under the surface FVES plume and enter the intake with much less debris to clog trash racks and traveling screens.

Objectives

To evaluate the ability of two FVES units to deflect downstream drifting mats of aquatic weeds away from a cooling water intake structure.

Approach

In late September 2012, two 12" FVES units were temporarily located 36 ft and 170 ft (11 and 52 meters) upstream of Dairyland’s Genoa Station power plant intake at depths of 6.6 ft (2 m), directed perpendicular to shore. Three-dimensional measurements of river velocities in the ~1,600 ft (~500 m) reach of river near the station were used to quantify the induced flow patterns. Global positioning system (GPS)-equipped drogues were drifted through the intake area to simulate drift tracks. The project team quantified plant material on the intake trash racks, and plant material and impinged fish on intake screens during daily 2 to 4 hour “On” and “Off” test periods to assess FVES performance. Evidence of FVES performance was also documented with a roof-mounted automatic camera taking pictures of the intake area every two minutes during the study period.

Results

The induced plumes extended an average of 66 ft (20 m) from shore, depending on the river discharge, with the farthest portions bent downstream by river flow. Three-dimensional measurements of river velocities in the ~1,600 ft (~500 m) reach of river near the station identified the induced flow patterns. The GPS-equipped drogues drifted through the intake area had most tracks deflected toward the river channel with the FVES units operating, but not when they were off. Collection of plant material on the intake trash racks, and plant material and impinged fish on intake screens, during “On” and “Off” test periods showed a reduction of chronic, low-density, dispersed vegetation to less than half (average 44%) and fish impingement to about three-quarters (average 76%) of the amounts without FVES units operating. Large, compact surface mats of aquatic vegetation, the main concern, were infrequent during the tests and diversion could only be quantified visually and in photographs. There was diversion of the infrequent mats and other surface debris away from a path to the intake, although some material (<20%) passed between the induced turbulent eddies or shoreward of the units.

Applications, Value, and Use

The research results strongly imply that the FVES unit may be an effective tool for deflecting floating aquatic debris such as aquatic weed mats, woody material, and dead fish. This was the first test of the technology, and additional testing under heavier floating debris loads and different hydraulic applications will be beneficial in ascertaining the value of the FVES in preventing intake blockages by waterborne debris.

Flow Velocity Enhancement for Guiding Fish Migration for Their Protection by Dr. Charles C. Coutant

This report was written and submitted at HydroVision International 2013 and available by contacting Natural Solutions at (406) 458-6363 or (406) 827-2128.

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