BioCycle September 2007, Vol. 48, No. 9, p. 17
COMPOST APPLICATION FOR LANDFILL SLOPE REMEDIATION
A research trial was conducted at Orange County (CA) Integrated Waste Management Department’s Prima Deshecha Landfill in San Juan Capistrano as part of a landslide remediation program. The test site selected had a cut-slope surface where it had been problematic to establish any type of vegetation.
Tierra Verde Industries in Irvine, California provided Prima Deshecha with a donation of 125 cubic yards of high-quality green waste compost in October 2006. The compost, processed at temperatures >140°F, was used to ensure any remnant weed content was eliminated. Crews ripped and track walked the bare soils in preparation for the application of compost. Compost was applied and integrated into that slope on October 20, 2006; on November 11, a hydroseed slurry was applied that contained native shrubs and grasses. The site was irrigated a couple times a day during the first few days of the seed establishment period, and once a week thereafter during the winter, in order to supplement low rainfall levels in 2006-2007. To minimize erosion, the entire slope was covered with straw matting (blankets) approximately one week after seeding.
The test plot was monitored on an approximately weekly basis following installation of the planting set-up. Appearance of the different species in the seed mix was recorded throughout the winter and spring seasons – in seedling, flowering, and in some cases, seed production stages. No quantitative measurements (i.e., percent cover, biodiversity, biomass, etc.) were made during the course of this preliminary study; however, a marked difference was observed in the density of native plants sprouting within the test plot compared to the slopes outside of the plot’s perimeter that also were hydroseeded with the same mix. Weed germination and growth also became pronounced in the later spring months, suggesting that poor soil quality had indeed been hindering the growth of both native and non-native plants.
The notably higher growth in the test plot was presumably because of the nutrients added by the integrated compost. Other influences may have included the modified fertilizer or irrigation, but as the slope was both hydroseeded and watered as evenly as practically possible throughout both the treated and untreated soils, this should not have been the limiting factor in the growth potential of the previously bare area. The neglible cost of the compost and its effectiveness led to a recommendation that the compost-integration program continue into the next couple years on the lands directly adjacent to last year’s test plot.
Niki Wilson is Biological Resources Monitor with the Prima Deshecha Landfill, San Juan Capistrano, Orange County, California.
ON-FARM COMPOSTING FOR TURKEY CARCASSES
G.A. Flory, R.W. Peer and C. Richmond
On March 30, 2007, routine preslaughter testing of a flock of turkeys on a Pendleton County, West Virginia farm identified the presence of the avian influenza (AI) virus H5N2. The flock did not exhibit clinical symptoms or increased mortality. Market-aged birds weighed about 40 pounds each. On April 1 and 2, the turkeys were depopulated resulting in over one million pounds of carcasses requiring disposal. Composting was selected as the disposal method, and compost piles were completed. Material would be land applied at agronomic rates as a soil amendment.
It is the U.S. Department of Agriculture’s policy to eradicate low pathogenic strains of AI with subtypes H5 and H7. Unchecked, large reservoirs of virus have the potential to mutate into highly pathogenic strains resulting in far greater economic impact and potential for human exposure. It is critical to quickly eradicate all H5/H7 positive flocks to prevent the spread to other farms. Effectiveness of composting as a method of disposal and containment was first demonstrated on the Delmarva Peninsula in 2004. It has since been successfully utilized in a number of AI incidences.
Composting the farm’s birds posed several significant challenges. First, on-farm composting had only been used as a disease control method for much smaller birds. Composting of larger birds had been tested on a demonstration scale in Virginia, but never implemented for the disposal of an entire flock of market-aged turkeys. Second, a new method of mass depopulation – fire fighting foam – had been recently approved by USDA and was used to destroy the flock. Traditionally, diseased flocks were depopulated with CO2 gas, which does not add any additional moisture to the poultry houses as does the use of fire fighting foam. Finally, successful composting requires a proper ratio of carbon material (litter) to nitrogen (carcasses). Since the poultry houses had recently been cleaned out and the turkeys were market aged, a large amount of additional carbon material needed to be transported to the site.
Windrows were constructed on a plateau above the floodplain, where drainage flows away from a stream and could be filtered through over 1,000 feet of sod. The windrows were 12-feet wide with a 12-inch base of coarse mulch. A layer of carcasses was placed on the base then capped with 12 inches of the twice-ground mulch. The birds were not crushed prior to placing them in the windrows. For the in-house composting windrows, the base was tilled to break up the caked litter resulting in a more absorbent base. The team attempted to crush the carcasses with skid loaders and tractors to enhance their decomposition. However, the moisture and surfactants in the fire fighting foam made the carcasses slick and difficult to crush. A 9-12 inch mulch base was laid down, followed by a layer of carcasses; the two windrows were capped with 12 inches of mulch or litter. Brown Bear aerators mounted on both a skid steer and a large tractor were tested to mix and aerate the windrows. The only visible evidence of carcasses in the material after aeration at three weeks was leg bones, quills and few feathers. No other bones, flesh or bird parts were visible. Windrow temperatures achieved in the first three weeks ranged from 110° F to 135°F.
At 10 weeks, the compost was evaluated and approximately 75 percent was determined to be suitable for land application as a soil amendment. Most of the remaining material was located in a slight depression and had become saturated, limiting composting activity. To ensure suitability for land application, all material was turned for a final heat and applied about 12 weeks after composting began.
Gary Flory and Robert Peer are with the Virginia Department of Environmental Quality. Christina Richmond is with the West Virginia Department of Agriculture.