Friday, October 3, 2014

Cleaning Up: Work underway at Ridgefield’s Carty Lake and Lake River

By Diana Smith, Craig Rankine, and Joyce Mercuri, Toxics Cleanup Program

In recent weeks, Ridgefield residents and visitors have noticed a lot of activity around Carty Lake. The Port of Ridgefield is cleaning up contamination at the Pacific Wood Treating site.

The port has also begun prep work for Lake River cleanup. Dredging in the river will begin in mid-October (see below). River users will soon see pilings and debris being removed and parts of the river channel being buoyed off.

Carty Lake cleanup progress

Here are some photos of what’s been happening:

1. In August, the port’s contractors began prepping to excavate sediments at the south end of Carty Lake in the Ridgefield National Wildlife Refuge.

Sediments in Carty Lake, especially in the south end, are contaminated with pentachlorophenol (PCP), dioxins, and the toxic metals arsenic and chromium.

The wetland sediments were mostly dry when work started because it was the end of summer.

2. The port’s contractors then began building a small, temporary dam at the south end of the lake. The dam is made of the large white sandbags you see in the photo.

Keeping the sediments dry was important because it made them easier to excavate. It also meant they didn’t have to be dewatered (dried out) in a separate area before trucking to the landfill.

3. The finished dam kept lake water from leaking into the sediment removal area. It also kept stirred up sediments from moving into the rest of the lake.

Here, you can see the finished dam. The white sandbags are covered with black plastic. You can also see some of the first excavated areas.

The port pumped out and treated water that was behind the dam.

4. The port is treating water from the excavation area. After water is sampled to ensure it’s not contaminated, it flows back into the lake.

5. Throughout September, the port excavated contaminated sediments. This photo shows a pile of excavated sediments pulled up against the bulkhead at the north end of the port property.

You can see the same bulkhead from a different angle in the first photo, which was taken before excavation began.

6. Now, the port is covering the area where they removed contaminated sediments with clean sand.

This photo shows a temporary road contractors built out of sand. They are using the roads to spread one foot of clean sand and topsoil over the excavated area. The port will also build more natural, sloping banks on the south and southeast edges of Carty Lake.

After the sand is laid, the port will restore the area with wetland plants. Then they will remove the temporary dam. The planting will happen in late October.

Lake River cleanup

The port has started prep work for Lake River cleanup by closing Division Street and other work areas, moving equipment to the site, and installing a sediment dewatering and water treatment system.

The Lake River sediment cleanup area is shown in green on the map. In this area, the port will:
  • Remove pilings and debris.
  • Precision dredge and pump contaminated sediments to the sediment handling area for dewatering. The port will ship the dewatered sediments to the Cowlitz County Landfill.
  • Place clean sand over dredged areas.
  • Stabilize and restore the shoreline.

Work will continue through early spring 2015. Sediments in Lake River near the port property are contaminated with PCP, cresols, dioxins, and polycyclic aromatic hydrocarbons (PAHs).

Cleaning up PWT’s legacy of contamination

PWT treated wood products on the site from 1964 – 1993. When the company went bankrupt in 1993, it left behind contamination on and off port property. Stormwater carried pollutants into Carty Lake and Lake River.

The port is doing the current cleanup under a 2013 legal agreement with Ecology. Ecology and the port are funding the cleanup.

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