Monday, September 29, 2014

Fourth grade field visit to Fern Hill wetlands and Clean Water Services Plant

On Friday afternoon, Joseph Gale fourth graders had a field visit to Fern Hill wetlands. This was the second step in the ongoing erosion unit partnering with Clean Water Services. The unit will consist of field visits, visits to the classrooms by experts as well as experiments with erosion models.

The first part of the orientation to the site was a tour of the Water Treatment Facility. Dave, a technician at the plant, led the tour.

The first part of the tour was the screen room; this is where large pollutants are removed from the incoming sewer water.
1) Screening-a machine rotates with a screen that separates all the solids that are removed from the water and taken to the dump.

Next was the water is pumped through large pipes to the primary treatment area or "vortex" as it is sometimes called.
2) Primary Treatment-Water is stirred in a big tank and gravity does the work. Anything that is less dense than water, like dirt, sinks and all things less dense than water, like oil, floats. Rotating arms on the top and bottom of the tank remove the contaminants are moved to digesters.

Third was a climb up the top of the platforms for a look into the secondary or "aeration" tanks. The plant was "offline" during our visit, so the tanks were not full or operating.
3) Secondary & Tertiary Treatment-Microorganisms help to clean the water by consuming dissolved organic substances, especially ammonia (NH4), through aerobic respiration and produce carbon dioxide (CO2) and water (H2O). As they do this, they convert the ammonia into nitrates (NO3-) through nitrification, which are then taken up in the microorganism during growth and then they settle out as a flock. During secondary treatment, a similar process is used to remove phosphates (tertiary: PO43-) and additional nitrates that are dissolved in the water.

The last part of the tour allowed a look at the large round storage basins that you see as you enter the site. These are where the filtered water is stored before entering the UV treatment area and finally is pumped into the storage ponds (currently under re-construction) and eventually ends up in the Tualitin River (and ultimately at our water taps).

PART TWO was a tour of Fern Hill Wetlands, a natural area created to filter, clean and store rain water as well as the filtered water from the treatment facility.
Walking along the path that runs along the storage ponds.
The storage ponds (under re-construction.) The work aims to create a more diverse habitat for a variety of native species.
A dry riverbed. These riverbeds were created to slow down and filter water coming from the treatment plant to the storage ponds.

A human made wetland "test" area. This area, just adjacent to the treatment facility was created to filter and clean rainwater as it enters the ground to become groundwater. The area was planted with specific plants species that are water-loving. Snags are the term for the dead trees that stand in the middle of the wetland. These provide shelter and habitats for birds of the area.

This marsh sits at the back of the Fern Hill area and handles the cleaning and filtering of large amounts of rainwater and runoff from nearby parking lots. It also provides habitat for plant and animal species. While there, we observed a Great Blue Heron perched on the far bank to our left.

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