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Creating a Santuary

by Karen Wise

The newly formed wetland 11 months after creation.

As a truck spilled out a black, soupy soil mixture onto the barren ground, the smell of rotten eggs invaded this place. Charles Frederick, environmental designer, and his coworkers watched while a bulldozer spread the liquidy mixture on the barren ground.

Despite the smell and appearance of the soil, the scientists of Davey Resource Group knew that the dark goo contained the seeds of life. Thanks to their help, and a little ingenuity, the area is beginning its conversion from sterile earth to lush wetland.

Months later, Frederick and his coworkers returned to the same spot to find it transformed. Frogs croak as geese and deer wander nearby. Turtles slip off sunny logs into the safety of the cool, deep water. The landscape is a lush, green space complete with plants and wildlife.

Relocating life
The project was part of a wetland mitigation plan created for the City of Twinsburg, Ohio. The city wanted to build a connector road that would allow emergency vehicles quick access to the northern limits of the city. But in order to do this, they would have to fill more than one acre of wetlands and build a bridge over Tinker’s Creek, the largest tributary to the Cuyahoga River.

Frederick and the staff of wetlands scientists at Davey prepared a Wetlands Mitigation and Monitoring Plan in accordance with the requirements of the US Army Corps of Engineers and Ohio EPA. It contained baseline data about the site, goals for the new wetlands, a planting plan (hydric soil transfer), construction drawings, and a long-term (5-year) maintenance and monitoring plan. Due to the amount of wetlands that was being filled and the proximity of the wetlands to Tinker’s Creek, the project had to be coordinated with both the state and federal governments.

Davey helped the city determine the impacts of the project on the wetlands and apply for and obtain two permits. The preparation of a wetlands mitigation plan was a requirement of the necessary environmental permits.

Most of the site was upland old field prior to conversion to wetlands. It was used 15-20 years ago as a crop field. Signs of the field tile were observed during construction.

The construction plans included many design detail notes pertaining to site clearing, protecting the existing wetlands that the contractor was working very closely to, stockpiling trees that were removed and would later be spread about the new wetlands to provide habitat, and finally the details of the hydric soil relocation.

The construction began in September and was completed by mid-October, 1999. CJ Natale, a local construction company from the Cleveland area, completed the work. “Their prior experience in building wetlands was minimal, but they were willing participants and really went to great lengths to create a successful project,” stated Karen Wise, Davey Project Manager.

Prior to spreading the goo of life, the site was excavated to depths varying between one and four feet. Only a small portion of the wetland was designed to hold water several feet deep; the goal was to have a portion that might allow fish to over winter, or to at least support a more diverse deep water submergent plant community. No clay was brought in, nor was a liner used. Soil borings were done prior to construction to ensure that soil permeability was at a desired level. Groundwater was filling in the deeper excavation areas before the equipment left the site.

"The need to install the check dams proves the point that these systems are not intended to be maintence free.

By relocating soil from a donor wetland only a half-mile away that was to be filled for construction of a senior apartment project, the members of Davey Resource Group breathed life into the new wetland. The process, transporting seed- and plant-laden soil from one wetland and using it to jump-start a new wetland, had never been tried before by the group.

“We knew that a nearby wetland was going to be destroyed, so we decided to try to save the soil to help the new wetland become established more quickly,” explained Wise.

The wetland from which the hydric soils were obtained was a lowland woods with a small portion of wet meadow. Within a few weeks after construction, those plants that survived were already recovering and growing in their new home. The rescued soils contained seeds from the following plant species: silver maple (Acer saccharinum); American elm (Ulmus americana); soft rush (Juncus effusus); cattail (Typha sp.); Pennsylvania smartweed (Polygonum pennsylvania); slender rush (Juncus tenuis); and blue vervain (Verbena hastata). The seed bank within the hydric soils yielded a banner spring crop.

The hydric soils were not stockpiled for longer than one day. They were moved almost immediately from their original state into the new wetlands and spread to a depth of about 8 inches.

Approximately 3 acres of existing wetlands, all contiguous, existed prior to construction. After mitigation construction, a total of 6 acres of wetlands were delineated. All meet the US Army Corps of Engineers definition. The new wetlands are immediately adjacent to the old ones.

After the site was prepared, flow from underground springs was directed into the new wetlands. The main source of hydrology is a small headwater stream that flows onto the site but originates from sandstone ledges less than 0.25 mile from the mitigation area. The water is very clean and fairly cold. This stream was the main source of hydrology for the old wetlands; it is now joined by the hillside seep and the high post construction water table as sources of hydrology for the new wetlands.

“The underground seeps primarily only affect one area of the site, and that took us by surprise. The spring of 2000, following construction, we noted the hillside seep and the plant life growing there,” said Wise.

In the winter and spring of 2000, the stream cut a new channel through the site, causing erosion in the newly created wetlands and a major water shortage in the existing wetland area. Even though most of the site was progressing nicely, about 1/3 of the proposed wetlands were suffering from downcutting, erosion, and lack of water. Four separate check dams, built to slow down and retain more water on the site, were constructed on the site in July 2000. Each check dam was constructed from clay, concrete, stone, hay bales, and wood. The materials were gathered from either on-site or within 0.25 mile. Small wetland pools and swale-like wet meadows formed behind each check dam. Plants, such as Typha sp. and Acorus calamus, were transplanted from other portions of the site into the pools behind the check dams.

A check dam of logs, clay and hay bales was built to manage water flow between an old and a newly established wetlands.

“The need to install the check dams proves the point that these systems are not intended to be maintenance free. Had we not done the follow-up monitoring, we would have never achieved our goal of 3 acres of wetlands,” explained Wise.

As part of the project, some trees had to be removed. Davey scattered the rescued trees throughout the wetland to provide habitat for wildlife. The trees are already being used by sunning turtles and wading birds, and the deeper pools are supporting seasonal populations of fish.

The end results are astonishing. “Now it looks like someone unrolled a beautiful green carpet over the land,” said Wise. “We have never had plant life spring up this quickly. It jump-started the re-vegetation process, decreased erosion and provided almost immediate habitat for wildlife.”

The quick penetration by the plants also helped to populate the wetland with wildlife. “We essentially set the table for the wildlife and just invited them to eat,” said Wise.

The mitigation wetlands were constructed next to the City of Twinsburg’s Parks and Recreation Department’s Community Gardens. There is a small parking lot and knoll overlooking the wetlands. Large sandstone blocks serve as amphitheater seats. The new wetlands provide the backdrop. The Parks and Recreation Department staff, and particularly their Naturalist, will have access to this area in the future for outdoor programs and educational events.

The process—from construction to the growing season—was completed within seven months. One year after construction, more than 50 different plant species were identified on the site.

Monitoring will continue through 2005. Two to three visits/inspections will be made per year and one annual monitoring report will be prepared and sent to the regulatory agencies. L&W

For more information, contact Karen Wise, Davey Resource Group, 1500 N. Mantua St., Kent, OH 44240, (800)445-TREE, ext 431, kwise@davey.com, www.davey.com.

©2001, 2000, 1999, 1998 Land and Water, Inc.
Monday, October 8, 2001 - http://www.landandwater.com/features/vol45no3/vol45no3_1.html