Expanding its wastewater treatment plant caused the city of Enumclaw to encroach upon a small wetland area, an environmentally touchy procedure that is now playing out in a highly-visible way.
The plant expansion went to the north of the original facility and, to accommodate the work, the city covered over approximately 3.25 acres of wetland area. City Administrator Mark Bauer said both federal and state agencies allow wetlands to be destroyed, but require agencies to create new wetlands in response. The rules dictate that cities create three or four acres of new wetland area for every acre taken away.
Overseeing the wetland mitigation project is Scott Woodbury of the city’s Public Works Department. He said negotiations with the U.S. Corps of Engineers and the state Department of Ecology began early in the process, before expansion of the treatment plant began. The city, he said, had to convince the agencies that disturbing some existing wetland was unavoidable – that there was no other way to expand the plant.
The mitigation plan that was finally accepted, Woodbury said, calls for the creation of two new wetland sites. Visible to motorists on state Route 410, and even more noticeable to those using the Foothills Trail, is a stretch of wetland that covers 8.3 acres adjacent to the trail. Soon, the city’s contractor will begin work on another 5.4-acre wetland on the grounds of the treatment plant. An existing house, which the city purchased and has used as an office for the plant project, will be razed and wetlands will be created on the site.
Woodbury said creating manmade wetlands is a long, involved process that carries rather specific instructions. For example, the city was required to partially grade each of the new wetland sites to adequately capture water. Specifications call for the installation of 11,187 trees and shrubs, 12,933 emergent sedges and rushes and approximately 130 habitat logs. Those logs are the most visible part of the project, some poking straight out of the ground.
Woodbury said the project won’t be completed until nearly the end of the year, as planting cannot take place until Oct. 1.
Creating the two new wetland areas carries a price tag of nearly $386,000, Woodbury said. Through a competitive bid process, the job was awarded to Enumclaw-based McDonald and Co.
Finishing the wetland mitigation by the start of the new year doesn’t relieve the city of its obligation to the Corps of Engineers. The city will be required to submit annual reports to the Corps of Engineers for 10 years following project completion, demonstrating that all requirements are being met. Those requirements include controlling weeds and replacing plants that die.
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