For years, the paper mills along the Lower Fox River in Wisconsin released PCBs through some of their manufacturing processes. These PCBs then became bound up in the river sediment.
After it was designated a Superfund site, work began on restoration of the area. The first step was to extract the sediments. The company responsible for this operation built a large dewatering facility and a wastewater treatment facility. Crews then drilled out the sediment from the river bottom and pumped it to the dewatering station. “After the soils were treated, they returned all of the soils back to grade and relaid the native soil,” explains Steve Banovetz, a senior scientist with Natural Resources Consulting Inc. (now part of Stantec), in Cottage Grove, WI.
Since mid-2009, NRC has been leading the restoration of the 15-acre PCB sediment treatment facility. This restoration project followed the decommissioning of the facility that dredged and treated 784,000 cubic yards of sediment from the river. “Our role has been to remediate the whole wetland lakeshore site,” continues Banovetz. (He refers to the area as a lakeshore rather than a riverbank, because there is a widening of the river that makes it almost seem like a lake. The widened area is called the Little Lake Butte des Morts.
NRC is handling all of the vegetation remediation, installing new seed and shrubs, and handling all of the follow-up maintenance to make sure that the native plant communities thrive. The project required NRC to develop and implement an effective invasive species control plan prior to installing bioengineered shoreline stabilization measures and restoring native prairie, sedge meadow, and shrub-carr communities.
The vegetation that NRC is planting is meant to be permanent, and it consists of native plant communities, all of which are tailored to the three areas that are present at the site: an upland prairie buffer, a wetland floodplain, and a shrub-carr wetland.
One feature of particular importance was a straight-line ditch that started at a street and ran to the lake/river. “We recreated it in a natural, meandering way,” notes Banovetz. “As a result, we needed to engage in some erosion control on the soil that was disturbed.” This involved all of the soils on the new stream, as well as the soils from the remediation and blockage of the old stream/ditch.
The first step involved seeding the area. The next was to lay down erosion control products. NRC contacted Construction Fabrics and Materials Corp. (CFM), a local distributor, and explained what it wanted to accomplish. CFM recommended three different types of products to meet those needs.
One of the recommended solutions was biologs. “We installed 450 feet of 16-inch biolog protection on the lakeshore,” states Banovetz. These were Rolanka BioD-Roll coir rolls, which are manufactured from densely packed coconut fiber. The coir rolls provide initial structural stability for shorelines by resisting wave action and flow velocity. Over time, sediment is deposited around the coir rolls, creating a medium for vegetation. The rolls can last for more than five years.
The second involved wholly biodegradable double-mesh erosion blankets, made with jute fiber, to be installed on the banks. Since NRC was dealing with wetlands issues, it needed to make sure that the product was safe for native amphibians and reptiles. For this application, NRC used the Rolanka BioD-Mat-70, a semi-permanent blanket woven from machine-spun bristle coir twines. The mat is 100% biodegradable, with a field functionality of four to six years. The blanket allows reseeding before and after installation.
The third solution involved a large-pored jute material roll that was rolled out on top of the erosion blankets to hold everything down in case the water levels rise in the stream. “We wanted something with more mass on the stream channel, but that wouldn’t block the availability of sunlight to the plants that we used,” he explains.
NRC kept the new stream offline for quite a while, so that the area could be properly vegetated and then covered.
In June 2010, the NRC team partnered with the Fox Valley Technical College to arrange for foreign exchange students from the Caribbean and Central America to install native shrubs and biodegradable fiber logs along the shore of the Little Lake Butte des Morts. With guidance from NRC, the students planted native species to restore the shrub-carr wetland and to stabilize approximately 1,000 feet of the Fox River shoreline with a combination of biodegradable fiber logs and shrub plantings.
To date, says Banovetz, the whole project has been extremely successful. There have been a couple of challenges along the way, though. One has been the weather. “We are currently getting close to the tenth-greatest amount of rain for a month,” he explains. This has caused several delays in the work. Another has been working with soils that are less than optimum for what NRC is trying to accomplish. “Our solution here has been to do a lot more work by hand,” he says. “Instead of using a seed drill, we used pails and sawdust and spread it by hand.”
Assuming that the weather begins to cooperate, Banovetz hopes to have the project completed by 2012 or 2013.
Philadelphia Retail Site
Phillips & Tosco of Phillipsburg, NJ, works on a regular basis with the H&K Group, a Philadelphia-area contracting and construction company. “They call us in to do the erosion and sediment control and landscaping,” says owner Bill Phillips.
In November 2009, Phillips & Tosco began work at a new WalMart site that the H&K Group was building. The store was being built on the side of an earthen mountain. “They cut a switchback road to the top, leveled the area out, and then did a cut and fill,” explains Phillips. “A lot of material was moved.”
When Phillips & Tosco began work, the first step was to plant the vegetation behind, beside, and in front of the facility. On the banks, crews used a crown vetch seed with an annual rye mixture. “Once the crown vetch takes over an area, it is very good for slope stabilization,” he notes. “The rye mixture is meant as permanent vegetation, and it is a no-mow type of grass.”
Once the seed was down, Phillips & Tosco installed a biodegradable blanket from East Coast Erosion Blankets, ECS-1D. It has a functional longevity of 45 to 60 days, and it is made of 100% agricultural straw, degradable thread, and accelerated photodegradable polypropylene netting. “We used about one million square feet of this product over the course of the job,” reports Phillips.
The company also used three different types of East Coast’s turf reinforcement mats. One was the ECP-2, which is made of 100% green polypropylene fiber, UV-stabilized thread, and two layers of UV-stabilized polypropylene netting. Another was the ECSC-3, which is a straw/coir turf reinforcement mat, composed of 70% agricultural straw and 30% coconut fiber. The third was the ECC-3, a coir turf reinforcement mat made from 100% coconut fiber. The latter two TRMs also incorporate UV-stabilized thread and three layers of UV-stabilized polypropylene netting. “We used these products in the channels and swales, which were the areas that were subject to a lot of rainwater and flow,” Phillips explains.
Phillips & Tosco purchases products from Ferguson Waterworks in Philadelphia, a supplier of East Coast Erosion Blankets products.
The various types of mats were installed behind the WalMart, along both sides, and in front of it.
Weather was a challenge, according to Phillips. “We worked right through the winter,” he states. “The excavator was running two crews on two shifts a day moving the dirt, because the project had to be completed by August.” Phillips & Tosco followed the crews closely and quickly. “We were dealing with heavy downpours during the fall, heavy snows during the winter, and the snow melt in the spring,” he says.
The reason Phillips’s crews followed so quickly behind the excavator was to take advantage of the freshly moved earth. This was particularly important in the winter, when the ground was frozen. “When they were done with a certain area of grading, we put the matting right down,” he explains. “The ground was still semi-soft, so it could absorb the seed, and we could get the mats down and the pins in the ground. If we had waited until even the following day, the ground would have been hard again.”
Overall, it was a successful project. According to Phillips, WalMart is particularly strict regarding its erosion control products. “They are governed by federal E&S requirements,” he explains. “They have their own people who do their inspections.” In addition, the state, county, township, and municipality did their own inspections. “We had to make sure that every mat we installed overlapped to the right degree and was pinned down to the right pin applications and patterns, which is determined by the flow,” he states. “We were able to do so with no violations.”
Point Richmond Quarry
The Point Richmond Quarry near Richmond, CA, about 17 miles from San Francisco, incorporates about 26 acres of what was once a hard rock aggregate mine. It is characterized by an east-facing hillside and a relatively flat quarry floor. The floor is situated between the hillside and an elevated imported soil storage area in the southern portion of the site.
The quarry was running with few concerns until late in 2005, when a routine inspection conducted by the State Mining and Geology Board revealed numerous code violations. Among these were slope instability, active slides, and inadequate revegetation. Twenty-five of the 26 acres were deemed disturbed and required action to be taken. In sum, the site needed to undergo extensive reclamation.
The site owners had decommissioned the quarry, but they had to bring it back to a more natural state before it could be sold.
It was immediately obvious that there would be challenges. The site had long, steep (1:1) slopes, in addition to poor rocky soils that were inadequate for sustaining vegetation.
To reclaim the steep slopes and attempt to revegetate, 4 feet of soil fill was brought in. The slopes were buttressed with biaxial geogrids installed at 4-foot lift intervals. Each lift extended 12 feet horizontally into the slope side. The purpose of the geogrid was to support the 4 feet of fill material, which was a 50/50 mix of topsoil and engineered fill.
To deal with stormwater runoff from the newly built slopes, slope benches were created. Each bench contained a V-shaped drainage channel that would convey stormwater away from the steep slope face.
When the structural work was completed on the slopes, additional products were selected to combat surface erosion and to facilitate the establishment of vegetation. First, the graded fill slopes were hydraulically seeded with a tackifier included in the mixture.
This was followed by the installation of North American Green’s C125BN, a biodegradable double-net, coconut-fiber, erosion control blanket. The C125BN was selected for a number of reasons. Because it is completely biodegradable, it works well for environmentally sensitive projects. In addition, because of its strength, it can be used on steep slopes up to 1:1. The long-lasting coconut fiber also allow for extended protection during the reestablishment of vegetation. Sediment control products were also included in the design; straw wattles were installed on top of the C125BN along the contours of the steep slopes.
In addition to the erosion control blankets, high-performance turf reinforcement mats were installed along the horizontal benches and the V-ditches. North American Green’s Vmax3 P550, a heavy-duty non-degradable TRM, was installed at the bottoms of the V-ditches. The product features a permanent polypropylene three-dimensional netting structure and fibers, which works well in areas with high water volume, shear stress, and velocities. A lighter-weight TRM was installed on the rest of the V-ditches and horizontal benches. This was the Vmax3 C350, which is comprised of a permanent 3-D netting structure and coconut-fiber matrix. The C350 offers immediate protection for a 24-month grow-in period and provides the necessary permanent vegetation reinforcement.
Rod Stevenson, a former contractor and now president of Stevenson Supply in Santa Rosa, CA, had worked with the contractor, North Bay Construction, and explains how TRMs came to be chosen for the project. North Bay Construction began using TRMs in some smaller applications. The project manager also took the engineers and showed them other projects where Stevenson had used TRMs in lieu of concrete-lined ditches, rock-lined ditches, and riprap on hillsides. “The engineers liked what they saw and gave the OK to change the specifications from concrete, rock, and riprap to North American Green products,” explains Stevenson.
The Point Richmond Quarry site was on a tight schedule, and using TRMs rather than concrete, rock, and riprap helped here. “It saved time,” explains Stevenson. “For example, in another job where we worked with North Bay Construction, they were able to cut their crew from nine to five people, and the time from two weeks to one week, by using TRMs.”
The installation of the stabilization and revegetation measures began in mid-2008. Within a few months of seeding and product installation, vegetation establishment had progressed nicely, with evenly distributed growth over much of the site. In fact, several rain events during that time resulted in no visible failures or soil loss to the integrated erosion control system. As confirmation, during a site inspection in late 2008, inspectors noted no violations or necessary corrective measures.
“The area has gone through a couple of winters with no failures,” reports Stevenson. “In fact, I just talked with a former North American Green rep, who has been to the site recently. He said it now looks like a completely natural slope. The swales aren’t even visible.”
In addition, because the project used soft-armor practices rather than concrete and rock, the project incurred substantial savings in materials, time, and labor costs. The use of the vegetated TRMs alone saved the project over $100,000 compared to using rock to line the V-ditches.
Furman University Lake
Furman University Lake, also known as Swan Lake, is a campus centerpiece at Furman University in Greenville, SC. The lake was constructed in the mid-1950s. However, as with many manmade lakes, the water quality declined over the years. In addition, the streams that fed the lake deposited large quantities of sediment, leading to a shallower and warmer lake.
Since 2006, the university has implemented a variety of improvements. The goal was to make the lake into a more natural ecosystem with biological diversity and high structural complexity. The university had three main goals. One was to plant appropriate vegetation in the lake and on the surrounding landscape to absorb nutrients, slow surface runoff, and deter waterfowl that were fouling the lake. A second was to naturalize the streams that flowed into the lake so that the water, nutrients, and sediments enter the lake in a natural and regulated manner. The third was to reduce waterfowl population to decrease nutrient and bacteria concentrations.
In 2007, the landscaping and grounds crew stopped mowing within the perimeter of the walking trail that circled the lake. This led to a flush of shoreline vegetation that acted as a buffer to runoff and a deterrent to waterfowl.
In spring 2008, the university hired EarthDesign Environmental Arts & Landscape Design of Pickens, SC, to begin the first phase of the restoration project. The primary aspect of was landscaping the north shoreline to control runoff, absorb nutrients before they could enter the lake, discourage waterfowl, and increase the beauty and diversity of the area.
In part of the area, the shoreline had eroded badly, requiring a complete construction of the bank. “Wave action had undercut the bank,” explains Rick Huffman, owner of EarthDesign. EarthDesign used a series of tiers to create a stable bank. “We started 8 feet off the bank and staked Rolanka BioD-Blocks, which are coir logs,” he continues. “This was similar to building a wattle fence.” The sediment gets trapped behind the logs and begins to build up the bank naturally. “In other words, as the waves move over the logs, sediment is deposited behind them, regrowing the shoreline from the bank,” he adds.
Boulders were used to anchor the bank and add a visual feature. In addition, semi-aquatic plants such as rushes and cattails were planted to help absorb and store large amounts of runoff nutrients. “The cattails, rushes, and other marshland aquatics also helped to hold the sediment in,” states Huffman.
In another area of the lake, EarthDesign went out into the lake about 15 feet and built a series of lifts/steps with BioD-Blocks. “We went back over the top of this with soil to seal in the blocks,” he continues. “We then used Rolanka BioD-Mat 40 over top of that. We pinned these in place and planted it. We have used the mat for a lot of our other needs, too. It holds up really nice.”
EarthDesign also planted native wildflower meadows on the shore to help reduce runoff and erosion. These flowers intercept and absorb more surface runoff than turfgrass, and also add more color and diversity.
The project went relatively smoothly. “The only challenge was working around a lot of the other construction that was taking place on campus,” he states. “However, we all communicated well with each other.”