Last week, I helped to build my very first wetland! Our goal: restore the site to it’s former wetland glory in order to create wildlife habitat and improve water quality.
The project took place in Logan Lake, BC, a small mining town southwest of Kamloops. The site was historically a wetland, though within the past twenty years the area was drained for the creation of a golf course. This project was also an optional field trip for students in the Ecological Restoration program at BCIT. To cut down on costs, we tented 1km away from the work site in the Logan Lake campground which the District provided use of for free.
The project started out with a survey of the site that we would soon turn in to a wetland. Tom held lectures each evening that covered essential knowledge and his experiences in wetland restoration. During the day, construction of the wetland took place, and educational sessions were held for topics such as soil identification, animal surveying, and water quality monitoring.
Other specialists present included Heather Larratt, RP Bio, who was on site for legal purposes, as well as out of interest. She installed a piezometer for water level and quality monitoring purposes. Reptile and amphibian specialist Brent Matsuda, and small mammal specialist Doug Ransome – instructors in the BCIT Ecological Restoration program – were also present.
Tom taught us that sites with a slope of less than 6% are appropriate for wetland construction. Then we learned about the various methods of building wetlands: the groundwater technique; the surface water technique; and the liner technique.
The groundwater technique to creating a wetland involves excavating the topsoil in order to expose the water table. The sides of the dug hole(s) are then shaped into gradual slopes. Groundwater wetlands are known to improve water quality and recharge the water table. This was the method used to construct the Logan Lake wetland.
Surface water wetlands require a compactable soil that will retain surface water. Clay is important in the soil composition lest the water drain out and the wetland will dry up. A compacted clay foundation must be created under and around the site, forming a basin for water to pool in.
The liner technique to wetlands is appropriate when the water table is too deep to reach, and there is no clay in the soil. After digging a depression, layering of durable geotextile, water-proof liner, then geotextile will cause water to pool in the constructed wetland. On top of the geotextile goes sand, soil and small rocks to prevent tearing of the liner and in order to simulate a natural look and feel.
After the excavator dug and sculpted the ponds, topsoil-mulch mixture was spread over the reconstructed surfaces. Plants we saved prior to excavation were replanted, and artificial snags were erected within and around the waters. We also planted trees such as trembling aspen, and shrubs including Oregon grape and wild rose. Rushes and sedges were planted along the edges of the water, as well as sedge seeds that we collected on site. Large woody debris was added to the landscape both in and around the edges of the water in order to enhance the habitat suitability.
One afternoon, Tom held a soils activity that was particularly interesting and educational. He arranged several tubs of various soil types, then, using a classification flow chart and soil texture matrix, we determined the soil type and texture class. This involved adding small amounts of water, making balls, and flattening into ribbons. When pressed out between the thumb and forefinger, the length of the formed ribbon is a characteristic of soil types. We examined loamy soils that contain an abundance of organic matter, sands that drain water exceptionally fast, fine and smooth silts, and discussed clay soils too.
As a “final exam” to the workshop, he assigned each tub of soil to a group of two people who were instructed to plan out a design-wetland based on their soil type. This was a really fun exercise that required us to demonstrate what we had learned and apply it in both theory and practice. Tom even buried simulated water mains and power lines in the soil boxes, testing people to see if they would practice call-before-you-dig. Some of the soil tubs required liners, and some were saturated at or just below the surface. Everyone had a great time with this exercise and agreed that it was an effective learning tool.
This workshop was very educational – even for the seasoned wetland keepers that were present. Tom will be back in BC for the 2012 Wetland Institute held along the Sea to Sky corridor from Pemberton to Squamish.
Heather Toles, 2010 Wetlands Institute graduate and backyard wetland owner also blogged about the Logan Lake Wetland Project. To see her blog posting, click here!
There will be an article about the Logan Lake wetland workshop in the upcoming issue of Valley Brew.
Thank you Marge Sidney, Tom Biebighauser, the staff and students of the BCIT Ecological Restoration program, and all other friends that participated in the restoration workshop!
By Graeme Budge, Wetlands Education Program Assistant