Wednesday, September 17, 2014

More Derry Dell news.....

A generic project update landed in the TVTU Members gmail box this past Monday - seems like things are happening on Derry Dell! We UPDATED YOU ON THE CULVERT WORK last month - and TVTU hopes to assist the CWS and City of Tigard with some of the restoration work on the reclaimed property noted below; hopefully that work will be both planting and potentially as a local beneficiary of some of our C4C trees! Stay tuned because as Mark Rogers - our TVTU contact for the Derry Dell effort - noted, this is big project overall!

Photo: Doug Vorwaller
September 15, 2014

Derry Dell Creek Restoration Project

Duke Tran, Engineering Project Manager
Clean Water Services

In July 2014, the contractor for the City of Tigard and Clean Water Services (CWS) began work on the Derry Dell Creek Restoration Project. Almost two years ago, the city purchased property along a section of Derry Dell Creek from Woodard Park south to Walnut Street; this purchase enabled the city and CWS to collaborate on a project that will realign and restore a section of Derry Dell Creek. They are also replacing two culverts that convey Derry Dell Creek under Walnut Street with one new culvert to facilitate fish passage and enhance water quality, while at the same time restoring an aging, undersized waterline at SW Johnson Street.

As the Derry Dell Restoration Project takes shape, CWS and the City of Tigard have collaborated on a number of measures to ensure that the area’s wildlife and natural features are protected. This winter, 90,000 native plants will be installed and much of the natural features such as natural habitats and trees removed from the area will be replaced or repurposed.

As mentioned above, when restoration is complete this fall, native fish species such as cutthroat trout, brook lamprey, Coho and winter steelhead will have an easier time navigating the newly restored Derry Dell Creek, owing to the new culvert. Fish friendly culverts such as this simulate an actual streambed, where fish and frogs, beavers, crayfish, snails and insects also thrive in the enhanced environment.

Aquatic animals aren’t the only species whose livelihood was carefully planned in the restoration process; native birds are also important in the area’s restoration and reforestation of the land. A total of 17 wood habitat structures will be constructed of local Douglas fir and Western red cedar with wedge logs and pier logs, all with root- wads intact. Several nest boxes for wood ducks will also be installed along the creek

Many of the trees (mostly black cottonwoods) felled on the property will remain onsite as large woody debris structures also known as “snags.” In forest ecology, snags are standing, dead or dying trees that provide important habitat for birds and mammals that use them for reproduction, cover and feeding.

Snags also provide a key component of in-stream habitat for fish and aquatic wildlife. Ordinarily, snags are removed because they’re too close to construction, but for this project, all logs for the wood habitats will be repurposed, having been saved from being chipped into bark or cut into firewood

Finally, deconstruction of the house on the current property this June represented quintessential Oregon recycling and sustainability values. Salvagers were brought in to recycle almost every house part to re-use in other area homes.

Duke Tran of CWS is an enthusiastic supporter of the project. "The Derry Dell project presented a unique opportunity for the City of Tigard and Clean Water Services to enhance community livability on a large scale in a fully developed urban setting. Our expert engineering and environmental team came up with a design that dedicated the entire property to a park and habitat enhancements for area residents. We created safe passage and for fish and wildlife, and the park will preserve this fantastic place for generations to come."