Vegetation is often the BMP best suited for curbing erosion; however, not every site contains the best soil, which is crucial for quick seed germination and plant growth. Choosing the right seed can often solve such problems. Plants that tolerate salt are perfect for marshes that take ocean backflows, and drought-tolerant species work well for arid climates or spaces that won’t get frequent watering. Amending the soil can also give plants a competitive edge. Large-scale amending isn’t always possible-but some ingenious professionals have discovered that waste items can be repurposed as great fertilizers.
Testing for Mulch-Better Success
Xcel Energy’s Hayden Station, a 450-megawatt electrical generating unit in Hayden, CO, creates ash while burning coal, so the facility also contains an ash landfill. In early 2013, the landfill needed some “landscaping,” as some of the hills around the area were causing problems for the firm’s trucks. “We perform vertical expansion-large dirt berms are created at the outside of the landfill, and we fill the interior with ash,” explains environmental analyst Mark Stewart. “We had line-of-sight issues for our trucking company using the landfill; we needed to take out the hillsides.” A local contractor, Resource Logic LLC, contoured the hills in question and then needed to protect the slopes from erosion.
“We replaced the site’s marginal topsoil and prepared to seed and mulch,” Stewart says. “But first, we were approached by Organic Earth Industries about trying its Earth Essence Beta HGM2 fiber mulch. To give it a good test, Resource Logic put traditional mulch and the OEI product side by side.” The test project began in May 2013. Both plots were hydroseeded with upland seed mix from Arkansas Valley Seed.
Each material in OEI’s product was agronomically engineered to meet the immediate demands of a severely impacted area. Earth Essence Beta HGM2 was specifically selected because of its seven different organic fibers, a special blend of growth mediums, and specially formulated soil chemistry materials to improve erosion control, soil development, and immediate plant establishment while improving long-term plant and soil sustainability. Beta provided exceptional vegetation establishment shortly after snowmelt from the 2.5:1 slope with a silt-type soil, as compared to the hydraulic growth medium and wood fiber mulch that was applied. Despite being applied at a lighter application rate (2,500 pounds per acre), Beta provided very effective erosion control. For comparison, the wood fiber mulch was applied at 3,000 pounds per acre, and the hydraulic growth medium was applied at 3,500 pounds per acre.
This Colorado area not only contains marginal, clay-filled soils but also receives little summer moisture. “We usually have to add some moisture to get things to grow. We release our stormwater onto that area,” Stewart says. “However, it wasn’t long before the OEI portion of the hillsides was showing growth. OEI is a little more expensive than traditional mulches, but if I don’t need respraying, as is sometimes necessary with other products, it might be worth it. Plus they’re great guys to work with. Of course, when we see what survived over the winter and returns this spring, that will determine a full success.”
Turning Sludge Into “Black Gold”?
In addition to managing trash and its daily cover, a landfill operation also has to manage the soil on its site, whether that soil is the final landfill cover, berms that divide cells, or interior access roads. As with most erosion control projects, dealing with bare soils usually involves seeding; however, as landfills are rarely placed in areas with healthy, vibrant soils, getting seeds to sprout and grow can be problematic. In Rougemont, NC, Republic Services’ Upper Piedmont Landfill is investigating whether a landfill ingredient will encourage plant growth.
Upper Piedmont Landfill receives sewer sludge from a local wastewater treatment plant. Traditionally, this material was simply buried in the landfill in its own specific section. But the question was raised: Since the material was nutrient-rich, could it be used as fertilizer for growing soil cover? There was a precedent; sludge had been used on non-food crops for agriculture, and the Milwaukee Metropolitan Sewer District had marketed its Milorganite fertilizer for quite some time.
Landfill/division manager Greg Duhon has the experience to direct this pilot program. “I used to work for a company that managed biosolids from sewer sludge. There’s a viable business in using sludge. That company would measure nutrients-mostly nitrogen, phosphorus, and potassium-and micronutrients in sludge, so one knows what’s being applied. Then it was applied at agronomic rates on non-food farm fields, such as soybeans grown to create plastics or feed grown for animals.”
His former employer applied biosolids that were processed to a Class B standard. “That means the pathogens and organic compounds had been reduced to meet regulatory standards. Biosolids processed to a to a Class A standard can be used anywhere, even on food crop lands.” These contaminants had already been eliminated by a wastewater treatment plant. “There are strict guidelines on how many metals can be in the wastewater,” he says. “For example, considering the zinc PPM [parts per million] limits-many multivitamins, if thrown on the ground, would not meet standards.”
Upper Piedmont Landfill’s sludge is trucked in from a local wastewater treatment plant. “What it produces doesn’t meet standards, so its sludge goes to a landfill. For me to accept it, any leachate material is pumped out and sent to a water treatment plant. Then at the landfill, biosolids are kept within a controlled area.” However, because merely burying this material takes up valuable landfill space, a new solution was sought.
“Using sludge for a soil amendment is a better method for handling biosolids than putting it in a landfill,” Duhon says. “For one thing, dewatered biosolids go through polymerization, which makes them more permanent in a landfill. By spreading the biosolids over soil to be reclaimed, the radiant heat, winds, and so on dry things out, which reduces contaminants. In this method, there’s eventual uptake of material, which makes it much better than putting it in the landfill, where it would remain for a really long time.
“This is not only allowed, but also actually sort of encouraged by the way the regulations are written in North Carolina,” he continues. “Regulations allow biosolids to be placed on the landfill for soil amendment up to 6 inches thick-but that’s not a viable process, especially if you’re using a bulldozer. Sludge cracks and just sits there. I’m putting sludge down less than an inch thick, and eventually I will be adding to that, but never to 6 inches thick. However, plants will grow right up through it, even at 6 inches.”
Sludge is used where crews are planting grass and legumes to stabilize slopes, as well as on areas of closed landfill. “We want to eliminate erosion,” Duhon says. “We’re growing fescue, clover, and brown top millet, which has a good root system-they’re quick-growing plants. We don’t plant shrubs and trees, as their roots cause problems with our piping systems. The advantages of grass are twofold; first, roots hold the soil. Second, if the grass has height, its blades disperse the kinetic impact of raindrops, which helps slow erosion. This grass is mowed several times a year; we allow it to grow to the 4-to-6-inch range. We also receive a lot of “˜volunteer’ growth. Anything that’s green and doesn’t have a woody bark to it, we let it be.”
When choosing a seed mix for the project, Duhon worked with Pennington Seed of Madison, GA. “I told them what I was looking for; that’s why we have a mixture of seeds. Some seeds are for rapid cover, others are for the next season. We rarely put in single seeds, although there’s a good percentage of a perennial rye strain in there. We considered the application-repeatedly taking the soil off and adding more waste? Might as well use cheaper seeds.”
Thus far, this first-of-its-kind project, which began in late 2013, is working well. “In mid-December, we still had grass that was very green. That was probably some winter rye from the last seeding, around November first.”
Crucial to the project’s success: using the right tools. “This isn’t a job for a bulldozer. Sludge is applied by using agricultural equipment-a manure spreader. A farm tractor pulls the spreader, which has been loaded by a backhoe. Broadcast seeding follows. Portions of the area were hydroseeded. We only spread sludge when we’re not expecting rainfall, as drying adds to the desiccation and also kills fecal coliform.
“Plus, this process follows the sequence of how a landfill is filled. When you’re moving to an adjacent area, you must seed the former area. Landfills are constantly seeded and scraped off. You can’t allow the soil or the sludge to lie fallow; you’ll have items leaching through down to the liner.”
Sludge has an advantage over commercial fertilizer. “Commercial nitrogen is inorganic, which leaches through the soil. Sludge’s organic nitrogen mineralizes in the soil, stays there longer, and also improves the soil’s tilth. The sludge works. We saw significant improvement in growth.”
Duhon is optimistic that when Republic Services sees the project’s results this spring, the program will continue. “As everyone has to deal with biosolids, other Republic facilities, as well as municipal landfills, are interested in doing the same thing. We meet at seminars and they hear about it; then they want to come out and see this in operation. Municipalities are usually owners of wastewater treatment plants, so they’re very interested.”
Saving Soil Around the Whole Dam Thing
In Franklin, VA, the Blackwater River runs next to a paper plant’s aeration ponds. To protect the river, a dam had been built; however, over the years, erosion began eating away at it. Jasen Norge, who co-owns Chesapeake, VA’s Norge Landworks with his wife Frances, was called in between July and October 2013 to fix the problem. “The slopes were rebuilt by Higgerson & Buchanan Inc., then we stabilized the slopes,” he says. “The dam is more like a big berm, a mound that runs about 8,500 feet.”
Norge explains the project: “Before the clearing, we first put in the outboard silt fence to protect the river from sediment. This was a big ordeal for the first 8,500 feet. It took 13 days to put silt fences into the swampy wooded area. We usually can do 3,000 feet a day, but there we could only install 600 feet a day.”
Frances Norge chuckles at her husband’s understatement. “This job was a mess; he was literally knee-deep in the swamp. All of our men wore waders, and they found several snakes. For the first 8,000 linear feet of silt fence, we had to put mats down to get in a mini-excavator to bring in materials. As the crew moved forward, they’d pick up the mats and put them in front of the machine-the ground was just that unstable. This wasn’t just wet land, it was an actual swamp.”
Jasen Norge goes on: “After the slopes were rebuilt, we prepped the bottom for seed and installed another line of silt fence at the slope toe, which was approximately 30 feet from the first run of silt fence, in the swamp. Once we installed the silt fence at the toe, we hydroseeded between the two silt fence lines. We did this process in 1,000-linear-foot increments, then we’d fall back and apply Flexterra to the slope, along with seed, fertilizer, and lime, to complete the stabilization before moving on.”
Pennington Seed’s SlopeMaster Warm Season mixture was applied at a rate of 100 pounds per acre, with an additional 50 pounds of Landscaper’s Choice (80% tall fescue and 20% annual ryegrass) due to the late summer seeding. Because a pre-plant soil test indicated that there was less than 0.5% organic matter in the sandy soil, 80 pounds of Bio Prime and 2.5 gallons of Jump Start were also incorporated. Pennington Pro Care 25-5-15 fertilizer, with 100% UMaxx stabilized nitrogen, was added, which provided up to 16 weeks of nutrient release-more than enough time to feed establishing vegetation.
“SlopeMaster blend has a Bermuda grass base, and it includes weeping love, which is low maintenance and good for mining sites or other bad soil sites,” Norge says. “We used about 6 acres of Flexterra over the slope, and there were 8 acres between the silt fences, so we used about 14 acres of seeds in total. We placed regular mulch along the bottom.”
A temperate climate, near a river-water shouldn’t have been a problem, right? “At the beginning, the seeds had moisture. But it seems like the minute you open a bag of seed it stops raining,” Norge chuckles ruefully. “But at the end of the period we got some moisture.” He was thankful he had used Pennington Seed.
“We use it all the time-maybe eight years now. For this project, we used 100 pounds per acre of warm-season SlopeMaster, which has five or six different seeds in itself, then another 100 pounds per acre of 80% tall fescue and 20% rye grass. Lovegrass went in at 15 to 20 pounds per acre; it’s a warm-season, drought tolerant plant, which doesn’t care about pH in the soil, it’s not picky. It doesn’t require very fertile soil and loves sand, which were the soil conditions.”
Frances Norge adds, “We’ve been in business for 10 years, but my husband has more than 15 years of experience. We have fewer than five employees-only three of us are full time. We are woman owned, SWAM certified, DMBE certified, HazMat certified. And now we’re also “˜swamp-certified,'” she laughs.
Seed for Restoring Wetlands
North of San Diego, CA, near the Del Mar Fairgrounds, I-5 crosses the 460-acre San Dieguito Wetlands. A recent $90 million project expanded and restored this area, which has become a boon for wildlife; ocean fish migrate in to use deeper water as hatcheries, and the salt marsh vegetation provides nesting sites for endangered birds. Migrating birds that travel the Pacific Flyway also find San Dieguito a comfortable resting place.
During certain periods between 2010 and 2013, Hydrosprout Inc. of Escondido, CA, seeded 100 acres of the wetlands. “The general contractor, Marathon Construction Corp., did the grading, building berms around the wetland areas,” says Hydrosprout operations manager Mark Webster. “When they were finished with a section, we’d follow up by hydroseeding. Although there’s water onsite, most of the time we applied seed and hydromulch in the fall and winter months to take advantage of the rains.”
The hydroseeding mix included Profile Products’ Terramatrix SFM and a wetlands seed mix from S&S Seeds of Carpinteria, CA. “The project designers came up with the specs for the mix,” Webster explains. “Seeds had to be collected within a 25-mile radius of the project. S&S came up with the mix we needed, which we applied at 22.85 PLS pounds to the acre.”
The wetland mix included four species of saltbush (Atriplex lentiformis lentiformis, Atriplex lentiformis, Artemisia californica, Artriplex canescens); a native primrose (Camissonia cheiranthifolia); Menzies’ goldenbush, from the daisy family (Isocoma mensiesii); an evening primrose (Oenothera elata); desert broom (Baccharis sarothroides); California plantain (Plantago erecta); California buckwheat (Eriogonum fasciculatum); black sage (Salvia mellifera); coyote brush (Baccharis pilularis); heliotrope (Heliotropium curassavicum); deer weed (Lotus scoparious ssp. scoparious); and Cuman ragweed (Ambrosia psilostachya).
Hydrosprout’s work progressed with very few hitches. “A couple times during winter rains, the area got a little muddy, so we’d wait. They had water onsite for us to use with the mix, so we didn’t have to truck any in. Everything we did was truck accessible,” Webster says. “In some dredge areas, we had access up to a point, then we had to attach up to 500 feet of hose to spray the area. We had a small problem when working around the I-5 freeway. We had to go under the bridge, and our 3,000-gallon Bowie seeder wouldn’t fit. We had to bring in a 1,500-gallon hydroseeding machine to work that area.”Few re-dos were necessary. “There were some areas that might not have grown as well, so we did some touchups, and in places that were regraded we had to hydroseed again,” he says. Hydrospout, which performs jobs of all sorts, from residential to public works and Caltrans projects, has been in business since 1988, and “we’ve used S&S Seeds all that time,” Webster says.