Not far from the 48-acre Dutch Wonderland amusement park in Lancaster, PA, is the Millcreek strip mall.
“Part of the property was an old golf course and some unused land that was converted into a retail outlet,” explains Andy Graybill of Rohrer Seeds, located in the heart of Pennsylvania Dutch country since 1919.
Roughly 2 to 3 acres of the strip mall property were recently reseeded, using Native Seed 181 mix from Ernst Conservation Seeds. Rohrer Seeds supplied the mix, and Graybill monitored the site during construction. He notes that the primary area seeded was quite steep, at around a 2:1 slope.
“The area at the front of the property is very visible. It does wrap around the back, and there are some ponds and other lower-lying areas that were reseeded with similar mixes,” he says.
“I know they were looking for some color. Being a steep slope, it fit with the Ernst steep slope mix. That was probably a big part of deciding what seed mix to go with. They did get the color, which looks nice. And it is a very steep bank, which, for the most part, isn’t going to be maintained or mowed. It seemed to be a good application.”
The Ernst 181 mix is composed of more than a dozen different varieties of seed. The five most prominent species, cumulatively making up nearly three-fourths of the total, are annual ryegrass, purpletop, riverbank wild rye, indian grass, and creeping red fescue.
Graybill says other than fertilizer, no soil amendments were added. “I don’t think anything was done. The ground was fairly nice, and they top-soiled it. There weren’t any problems with establishing vegetation. It’s not being actively watered because it actually gets a fair amount of water from the top, coming down over it. So it doesn’t appear to dry out too quickly.
“We did have one washout, but it was during a week in which we got a significant rainfall,” he notes. “At one end, there was a large amount of water coming off the adjacent property, which sat higher. This water just took out a section, but then it was repaired.
“The whole bank was matted with a double-net straw-coconut blanket, and that obviously helped with establishment. The one area did wash out, so the matting didn’t hold that, but other than that, there were no issues.”
The washout area was treated by adding new topsoil to it, and additional matting was added.
“What used to sit above the area we seeded was a motel with a blacktop area, but the area has changed quite a bit since. That motel has been demolished, and there has been site work there. The other interesting part is one of the banks is no longer there; they added another restaurant, and they actually cut into that bank. But half of that bank has been reseeded with the same 181 mix this past spring. It was a different contractor who did it, but nothing was done differently, with the exception that one end was single-net straw-erosion control blanket, and the other end was a different product.
“We did have a similar issue there with a washout or two. They were relatively minor, and we didn’t have to go back and fix them. Everything sort of just filled in, and vegetation really took off. It looks really nice for being less than a year old.
“There have been some weed issues, and it definitely needs to be mowed now to keep the weed pressure down, but it looks pretty good. We were shooting for one mowing a year, whether it be a dormant mowing or late spring. The weeds are definitely in there, but the other species, including the wild rye and the flowers, are there as well, and it looks like a good representation.”
Compost spread before incorporating
Graybill notes that “significant rock” was found in the seeded area, and a small spring that emerged from one area of the bank was causing a wet spot, but for the most part the project has been free of major problems.
The site still experiences occasional washouts from runoff from the adjacent property above the seeded area, according to Graybill. But he has largely controlled this with the application of bonded fiber matrix and erosion control blankets.
Challenging Landslide Restoration
On the outskirts of Los Angeles, between Santa Clarita and Gorman, a major landslide occurred several years ago, shutting down several lanes of the southbound portion of Interstate 5.
“That area is known for sliding, slumping issues because of a high water table,” says Christopher Stevenson of Caltrans (the California Department of Transportation). “The fracturing, underlying soil has a very high clay content. It swells and is a very difficult soil material.”
After the landslide, emergency repairs were needed, as Interstate 5 is one of the main arteries in and out of Los Angeles. More than a million cubic yards of material were removed. “To save the state the high cost of hauling all that material away, it was deposited in Violin Canyon below,” says Stevenson. “That was phase one, which was mainly geotech engineering work. They benched the mountainside, putting in several plateaus in what is called a “˜buttress slope,’ which holds the underlying material behind it.”
The landslide occurred on US Forest Service land, which is under a 99-year lease with Caltrans. The site includes about 1.5 acres of wetland.
“We’re on the hook for 3:1 mitigation,” he says. “This means that we had to restore impacts to the wetlands and waters of the US.
Three different methods
Generally, the first order of restoration, if possible, is to do that onsite, at the location of the impact. In this case, because of the issue of the high water table and an area with a high probability of further landslides-and the potential of water causing that-we were not able to do any onsite wetland restoration.
“What was really more the problematic issue to deal with was this soil that we exposed hadn’t seen the light of day for several million years, since we scraped off the top 80 to 90 feet of soil. We thereby exposed this very friable, fracturing soil and then had to figure out how to restore the upland portions of that area,” he says.
“In phase two of the restoration work, we had a lot of failure due to the fact that this soil was so friable and just eroded away so easily. It was expansive soil with heavy clay, so things did not grow so well. We had to figure out how we were going to get something to grow in this difficult soil.
“Two test spots were run, each about an eighth of an acre, one on a 2:1 slope, and one on a 4:1 slope. Those test plots incorporated a method called “˜compost and incorporate.’ We brought in topsoil and compost and ripped the soil to a depth of at least 18 inches to incorporate the compost material. This helped with deep saturation and percolation, so instead of water running off and eroding, it would soak and go into the soil.
“After seeing that this was quite successful, we incorporated three different types of erosion control measures and restoration planting. There was the compost and incorporate, in which we had to rip the soil down 18 inches and incorporate a 3 to 4 inch layer of compost. Another method was a compost blanket. In this case, the soil is just roughed up a little, with a layer of compost placed on top. The third method was standard hydroseeding, with no pretreatment to the soil.”
The seed mix, supplied by S&S Seeds of Carpinteria, CA, was a nonstandard seed mix, composed of all native seeds.
“It was specified because of the sensitivity of the particular location in Forest Service land,” notes Stevenson. “We worked in coordination with landscape and environmental planning biologists who came up with specific seed mixes for sensitive sites.”
There was a delay reaching this final revegetation stage. An earlier series of plantings hadn’t gone well, and two rainy seasons led to problems with erosion. Then there was roadway work, which took about two years to complete. The contractor had to remove much of the expansive soil from under the roadway because it was causing buckling and warping of the road.
So it wasn’t until spring 2012 that this latest revegetation effort was undertaken. Approximately 12 acres were involved, roughly evenly divided among the three different revegetation methods-compost and incorporate, compost blanket, and hydroseeding.
Stevenson explains that one of the many challenges on the project involved determining proper irrigation for the site.
“In the first phase, we tried drip irrigation, but that did not work well. This time the contractor chose overhead irrigation, which is still a bit of a challenge and difficult, because it’s a very hot and dry and windy location. Getting water to land where you want it to land is difficult.”
RainBird units were used initially for overhead irrigation. “They’re really made for more temporary installations,” says Stevenson, noting that the goal for any Caltrans highway restoration project is that ultimately, natural rainfall will be sufficient for irrigation needs.
“They typically plan an establishment period. On average, it’s usually only about 120 working days. In this case, because of the difficulty of the site and wanting to make sure that we get things well established before we pull the plug, this one had a two-year plant establishment timetable.”
A number of other erosion control measures were also employed.
“We used fiber rolls,” says Stevenson. “They also installed a concrete box channel on part of the slope. This unfortunately didn’t do so well. There is also a rock riprap channel to handle the flow of surface water off the roadway. We planted willow and mulefat within the rock crevices. We’re trying to get that established in hopes of meeting the requirements of the Army Corps [of Engineers] and [the California Department of Fish and Wildlife] for wetlands and water restoration and mitigation.”
The project has continued to present ongoing challenges. The site experienced a high plant mortality rate for the first year of restoration. Those areas were reseeded, relying more on hydroseeding this time and much less planted material.
“There were really only two methods for the reseeding-it was either hydroseeding or using potted plant materials, depending on the slope and the angle of the slope,” he says.
One of the original goals had been to restore the coastal sage scrub habitat. “But due to the fact that we really changed the soil profile completely, we’re just happy to see native species establishing there,” Stevenson says. “We now have a very high alkaline soil, so we’re not seeing the typical plants that were, for example, growing next door. I don’t think we’re going to see typical coastal sage habitat being restored. But we are seeing some native plants being established. Over time, Mother Nature may just come in and change this.”
Because of the difficulties encountered with this project, Stevenson stressed the importance of problem-solving utilizing a diverse group of individuals.
“When you have a site like this, you really need to have a team approach, working with people with different approaches and different insights. We’ve had an expert with experience working on restoration with difficult soils, and other experts with different viewpoints and understandings of these kind of complications. It really helps us to figure this out and get it done.”
Six Weeks to Vegetate
A new well pad was being constructed in Lycoming County, in the central part of Pennsylvania near Williamsport. Underneath a wide swath of this area lies the massive Marcellus shale plate, one of the largest known shale and natural gas reserves in the world.
Second growing season
“With the hydraulic fracturing being modernized within the last four or five years, it’s really transformed the whole industry,” says Hal Gee, vice president of energy development for Glenn O. Hawbaker Inc. “It’s amazing what’s going on with these places.
“We used to import natural gas from the Gulf of Mexico, and now the entire plumbing system of those pipelines has been reversed. Now we’re forwarding there, and from the wells to the ports of Philadelphia and Baltimore so we can export propane.”
The Lycoming County site is close to 7 acres in size, with 2.5 acres devoted to the well pad itself. To restore the site after the well pad was built, the rest of the area around the pad was seeded with a mix from Pennington Seed, together with Profile ProMatrix hydromulch.
But before any seeding could be done, the land had to be cleared of mature hemlocks, pine trees, and other hardwoods, and stumps had to be ground down to below grade. Some 92,000 cubic yards of material was moved during the project, together with 13,500 tons of rock. In addition, a 3.2-million-gallon freshwater impoundment had to be built.
“When well pads go in, they need a lot of water for the whole fracking process,” explains Jamie Van Fleet of Pennington. “The big freshwater impoundment almost looks like a giant swimming pool. It’s a big lined detention pond that stores water.”
Gee explains that there was a very tight timetable to work with. “Typically, as soon as we disturb the earth, we only have a few days, especially when we strip the topsoil off the site and the clearing and grubbing is complete. You strip the topsoil from the site, into a stockpile in a designated area. Obviously, that stockpile has to be seeded and mulched within days.
“All this has to be filed with the E&S [erosion and sedimentation control] plans, and the county conservation and district requirements. That was done immediately. All of the exposed slopes must be seeded and mulched, typically with a Flexterra-type product that was put on the slopes.”
Gee’s group had no more than about six weeks to complete the project. It began in May 2013 and had to be completed by the end of the following month.
There was another reason for the short deadline: “It’s all driven by when the drill rig will be there. Most times, the DEP in Pennsylvania will not issue a construction permit to build a well pad until they have a drill permit, or vice versa. You have to have one to get the other. So as soon as they get the drill permit approved, then they are allowed to do the construction. As soon as they get the drill permit in their hands, they want a well pad. So that’s what drives the construction timetable.”
A variety of erosion control devices were employed at the site, including rock filters, temporary basins, filter bags, and silt socks ranging from 6 inches to 24 inches. A weekly maintenance schedule has been adhered to, monitoring all the BMPs in place. More frequent monitoring takes place when heavy storms occur.
And there have been some significant 2-inch rains within the span of an hour or two. “Gullywashers, as they say up here,” says Gee. “They just really pounded the sites, when things were still very fresh. We were very impressed with how all the products we were using on the site held, especially with the amount of earth that we had exposed. That was a measure of the success of everyone’s work that it all went so well. That doesn’t always happen.”
Seeding Along the Interstate
Fort Morgan, CO, is located about 80 miles northeast of Denver, with Interstate 76 crossing directly through the community.
“They’re rebuilding both lanes of I-76; it’s a two-year project,” says Ron Ramsey, owner of Blue Mountain Seeding in Greeley, CO. “Westbound lanes are being completed first, then they’ll switch traffic to the westbound lanes and do the eastbound lanes. There are also about 13 bridges and structures being replaced as well. It’s a pretty involved project.”
About 175 acres are being revegetated in two phases, roughly 80 to 90 acres on each side of the interstate.
“We’re using a lot of Biosol on this project, and humate as a soil conditioner. It’s basically a slow-release fertilizer,” Ramsey says. Bowman Construction Supply in Denver provided the materials.
“As in much of the West, here in eastern Colorado, weather conditions dictate a lot of what is done. We use a lot of native plants, primarily because it is hot and dry. Sandy soil conditions also play a role. The sand is the most difficult issue. It is highly erodible and hard to navigate when it is soft and loose.
“I remember a previous project at the Denver International Airport, where what had been 6 or 7 feet underground became topsoil, and the pH was so high, nothing was going to grow.
“On the Fort Morgan project, it was hot and dry, although we did have some rain out there, which was a bit of a relief. Because the soil is mainly sand, that presented some difficulties. You add a little bit of water, and the dirt just flows and erodes pretty badly.”
Ramsey uses mulch and erosion control blankets to fight this erosion, as well as some soil binders. On this Fort Morgan site, he is using all native seeds.
The project is still ongoing, and Ramsey has utilized a number of temporary measures until the final stage of permanent seeding can take place. But he reports that where the final seeding has been done, primarily in the vicinity of some of the highway ramps, vegetation is coming up well.