Research and field trials show that compost works effectively in stabilizing steep slopes, preventing erosion, and fostering germination. Composted organic material stimulates the chemical, physical, and biological characteristics of soil, adding texture and structure in a manner that resists erosion. Unlike many other erosion control best practices, compost can be left in place after construction as a soil amendment.

The absorbency and runoff control benefits of compost are particularly beneficial on steep slopes where the soil is too poor and nonabsorbent for vegetation to become established. Compost can absorb as much as the first 12.7 millimeters (0.5 inches) of a rainfall. Although hydroseeding (spraying a mixture of hay, straw, fiber mulch, water, fertilizer, agricultural lime, grass seed, and tackifier) helps control runoff as well, in some settings this mixture may not be as resistant to erosion as the compost method. Silt fences and straw bales are often used in conjunction with hydroseeding; however, compost berms are as good as or superior to silt fences or straw bales in filtering soil particles from stormwater and can allow more water to absorb into the soil. The compost mixture also stimulates the seeds to germinate more quickly and grow deep roots.

Compost has also proven beneficial to water quality. The EPA has characterized non-point source pollution as the leading cause of contamination in U.S. receiving waters and highways as a major contributor. [N] In response to the issue, some DOTs have begun to pursue use of compost on highway embankments as a best practice in controlling pollutants in runoff from highways and a source of credit in meeting water quality requirements. Compost decreases pollutants by chemically binding substances, such as heavy metals and toxic organics (including hydrocarbons, pesticides, and herbicides), many of which are subsequently disposed of through bioremediation. As such, compost filters can be used to help clean stormwater discharge before it enters receiving waters. A Washington State DOT study on BMPs for stormwater runoff in confined spaces evaluated various filter media having potential for use in filtration vaults found that garden bark, peat moss, sand, and compost are the best filter media for treating stormwater runoff in vaults. These media have acceptable hydraulic properties to pass water through the filters and have good pollutant removal abilities. ( 38 )

TTI conducted Research Study 0-1352, Use of Compost and Shredded Brush on Rights-of-Way, to determine for TxDOT the potential of compost and shredded brush to serve as erosion-control materials for use in highway rights-of-way. This effort was based on literature reviews and on field performance evaluations on 1:3 slopes and with up to 5-year rain events. The high performance of various compost test plots led TxDOT to include compost on the agency's Approved Material List for Standard Specification Item 169 - Soil Retention Blanket and to conclude the cost savings were likely. TTI reported that research groups in the U.S. and around the world have effectively demonstrated the use of compost as an erosion control measure. In various tests, compost has shown to provide a physical barrier between rainfall and the surface soil, dissipating the effect of impact energy and minimizing erosive forces. To maximize water quality benefits from compost utilization, the Center for Transportation Institute-Texas Transportation Institute, (TTI) of the Texas A&M University System, makes the following observations and recommendations for practitioners: [N]

• High quality, mature compost will provide the most effective results. A low grade, immature or unstable compost can contribute to water contamination by leaching nutrients and/or heavy metals.
• Compost that is relatively dry (40 percent water content or less) effectively binds the elements and reduces leaching.
• A layer of compost can provide foot or vehicle access to slopes previously inaccessible as a result of mud created by heavy rains on clay soils. A layer of compost at the exit of a site will prevent mud from being tracked onto adjacent streets by vehicles leaving a construction site. Effective application thickness is an average of 7.6 cm.
• Application of compost with a moisture content of less than 25 percent will facilitate application and allow for better absorption of water during a storm event.
• A particle size of 19mm was most effective as an erosion control method and as a soil amendment. The larger pieces were less aesthetically acceptable for landscape purposes, and the finer grade was less effective as an erosion control method. Coarser grades are best for steeper slopes.
• Compost can be effectively used on slopes up to 70 percent (35 degrees)
• Extend compost cover for 0.61m to 0.92m above slope to reduce the velocity of flow or possibly construct a berm.
• Consider end use of area to determine which grade of compost will be best suited for the site. An area that will be landscaped may require a finer grade to avoid repeated application of finish grade compost for soil amendment.

The Federal Highway Administration's Eastern Federal Lands Highway Division (EFLHD) tested compost in a very steep environment on a landslide site along the Blue Ridge Parkway near Asheville, NC. To EFLHD's knowledge this project was the first time compost was applied to roadside terrain this steep; parts of the slope exceed a 45-degree angle and installers had to rappel down. EFLHD was operating under a number of other constraints in addition to very tight timeframe. Conventional equipment could not be used on such steep slopes and late May-early June was a sub-optimal season for establishing vegetation. Water quality and protection of artesian springs in the area were also priorities. EFLHD and the National Park Service wanted to establish a green, vegetated slope on the repaired section to prevent excessive runoff, and to prevent the introduction of noxious weeds through topsoil, straw, or hay. Partially installed compost withstood extremely heavy rainfall and shielded seeds during the following two months of drought until re-germination conditions improved. AASHTO's FP-96 Section 713.05 specifications for mature compost were modified to fit the site conditions and meet appropriate compost tests in accordance with EPA and U.S. Composting Council requirements. [N]

The New York State DOT (NYSDOT) is addressing its obligation to remove dead animals from roadways and adjacent areas in an innovative and environmentally sound fashion by composting deer carcasses. In fiscal year 2001, NYSDOT responded to almost 25,000 deer mortalities. Notably high rates of deer/vehicle accidents occur in the lower Hudson Valley, where NYSDOT Region 8 reported approximately 8,000 dead deer in fiscal year 2000, even though the Region maintains only about 12 percent of the agency's centerline miles. These disposal challenges have been accompanied by a decrease in the number of rendering companies available to collect and dispose of the carcasses. With growing developmental pressures and more stringent environmental regulations, fewer deer can simply be disposed of in wooded areas. Deer picked up during weekend hours must be kept at a yard site until transfer to a landfill or other disposal option is possible. Multiple handling of the deer carcasses causes additional hours of labor and adds to the disposal cost of deer. Moreover, deer that are stored at a yard for more than 12 hours start decomposing, making rehandling highly unpleasant for workers.

NYSDOT examined farm practices of composting of livestock mortalities with woodchips or sawdust. While decomposition is slow via a typical pit burial, total body decomposition can be achieved by composting within a few months. The compost end product, once deemed safe, has potential re-use within the highway environment. NYSDOT and the NYSDEC developed the Guidelines and basic steps to achieve optimal results and ensure human health and environmental protection. This example is noted as the Deer Carcass Composting - Practice Guidelines in the Appendix. [N]

Herbicide reduction practices and examples are included in the vegetation management section. Reduced salt and sand usage practices and accomplishments are discussed in Chapter 8.

Missouri DOT's Efforts to Reduce, Reuse, and Recycle

Missouri DOT offers the following list of areas for recycling applications in maintenance, many of which are applicable to other parts of the organization. [N]

• Office paper
• Steel drums used for other purposes after emptied
• Automotive and Ni Cad and all rechargeable Batteries
• Sealed Lead Acid Batteries used for backup power at intersection lights
• Waste tires and tire scrap found along the highways
• Telephone books
• Used motor, gear and hydraulic oil
• Used Oil Filters
• All types of acceptable paper
• Aluminum highway road signs
• Salvage sign button copy (72% cost savings)
• Solvent recovery still to recycle solvents
• Antifreeze changed to extended life, no need to recycle
• Recycle Freon
• Scrap computer paper used for note pads
• Splice broken wood and metal sign posts
• Straighten and reuse damaged guardrails
• Reuse boxes for shipping highway signs
• Reuse damaged bridge structural steel
• Used rotomillings in mixed asphalt
• Aggregate placed under asphalt storage tank to absorb spillage, then used on roads
• Reuse concrete from roadway repair for erosion control
• Petroleum contaminated soil is cleaned and reused
• Reuse obsolete guardrail panels for cribbing and erosion control
• Use damaged metal posts for equipment storage racks
• Waste paint solvents are used as blended industrial fuel
• Metal scrap found along the highway
• Aluminum cans at rest areas and in the offices
• Lead Paint chips sent to lead smelter to recover the lead (all of the material including the shipping containers are used in the process)
• Recap equipment and truck tires
• Roadway rotomillings used in roadway rehabilitation projects

• Completed statewide survey of all maintenance facilities for recycling and environmental concerns and finishing up on the remaining facilities
• Recycling all light bulbs statewide
• Abrasive recycling for sandblasting paint (waste reduction of about 80-90%)
• Switching to permanent Antifreeze
• All water based traffic paint is bought in recycled totes or in bulk, eliminating waste drums
• Bioremediate Petroleum contaminated soil instead of sending it to a landfill
• Recycle laser toner cartridges back to supplier
• Corrugated cardboard collected
• Scrap steel and aluminum from maintenance activities and roadside cleanup
• Recyclers pick up used oil
• Provide recycling information to about 5,200 Adopt-a-Highway groups
• Include a recycling tip column in the "Roadside Review" newsletter
• Purchased equipment to extend the life of nickel cadmium batteries
• Collect lead-acid batteries for resale or recycling
• Removed the word "Virgin" from non-structural plastic product specifications
• Duplexed copies
• Hazardous materials/waste survey maintained department-wide
• District pesticide inventory maintained to better distribute and use pesticides
• Steel shot and sand blast residue containing lead paint sent to lead smelter for reuse as a raw product
• Parts cleaner solvent collected by recycler or blended for industrial fuel
• Use biodegradable cleaners for parts and equipment
• Maintain a list of products with recycled materials
• Chip waste wood, tree limbs and brush for landscaping and compost
• Use biodegradable non-toxic degreaser on vehicles
• Recap loader and truck tires
• Rotomill old asphalt and use in place without removing instead of land filling
• Micro surfacing uses less material and prolongs a roadway surface
• Calcium sultanate to encapsulate lead paint on bridges
• Conducted tests on motor oil and extended the oil change time from every 2,000 miles to every 7,000 miles on most vehicles
• Use Soy Wash, a biodegradable soybean by-product and other non-hazardous biodegradable products to clean equipment
• Stripper cleaning fluid used in striping paint no longer used and switched to exclusively water based

• Purchased recycled content paper, towels, toilet paper, envelopes
• Reclaimed rubber to use in asphalt on test project
• Promotional items with recycled content such as pencils, car litter bags, Frisbees, etc.
• Department news letter "Roadside Review" is printed on recycled paper
• Sawdust to cover crack pouring asphalt
• Wet bottom boiler slag (cinders) for snow removal
• Fly ash in concrete
• Waste roofing shingle granules for snow removal
• Recycled plastic wheel stops
• Recycled paper for printing of 3.5 million highway maps, brochures and newsletters
• Re-refined oil in department automobiles
• Expanded use of recapped tires
• Expanded use of sawdust and mulch for roadside beautification
• Fly ash for fill material and pavement grouting
• Lime Kiln dust for soil stabilization
• Truck tire sidewalls used for traffic cone ballast
• Used aluminum signs refurbished and used again
• Iron mountain chat by product in asphalt and on bridge decks
• Used oil heaters to heat shops
• Wet bottom boiler slag for traction surface on bridges
• Water base striping paint (reduces volatile emissions and hazardous waste generation)
• Water base bridge paint (reduces volatile emissions)
• Use lead mine tailings in concrete and pavement, removing it from the environment

• Working with carpet producers to recycle carpet and purchase recycled carpet
• Experimenting with recycling absorbent materials used to soak up oil, including paper towels and rags. The oil is extracted and the absorbent material returned for reuse
• Use compost from city recycle centers
• Use low growing grass to reduce mowing and spraying (waste and pesticide reduction)
• Waste wood products used as absorbent material to contain spills
• Encouraging contractors to use a high pressure, low volume water blast on bridges to further reduce the waste by as much as 99%
• Testing the use of plastic pilings made from recycled materials to stabilize highway slopes and embankments
• Experimenting with the use of crumb rubber from scrap tires to fill expansion joints on concrete highways.
• Experimenting with rubberized asphalt over lays of less than 1 inch thick made up of rubber and Styrofoam
• Testing new form of rubberized asphalt on highways around the state.
• Attend national and international seminars on use of recycled materials in highways.

Mass Highway 's Pollution Prevention Program for Construction and Maintenance

For the past several years, Mass Highway has undertaken efforts to prevent pollution through conservation and reduction programs relating to construction projects as well as operation of maintenance facilities. Mass Highway maintains a number of pollution prevention initiatives relative to air, energy, water, and solid waste and toxics reduction.

• Mass Highway is continuing to identify, evaluate and implement pollution prevention initiatives. Pollution prevention opportunities and activities under current consideration include:
• Eliminating solvent parts cleaners statewide.
• Upgrading maintenance garages to include state-of-the-art automated oil dispensing and quick drain capabilities.
• Use of vegetable-based diesel fuels to reduce heavy equipment air emissions.
• Purchasing low volume high pressure washers for vehicle/equipment cleaning to reduce water use.
• Purchasing aqueous brake cleaning systems to eliminate all brake solvent use and eliminate asbestos dust hazards.
• Use of vegetable based hydraulic oil.
• Use of neutral pH, non-oil emulsifying vehicle degreasing/washing detergents to eliminate caustic detergents and improve effectiveness of oil/water separators.
• Identifying specific areas within a given project for experimental or full usage of new products comprised of solid waste materials.
• Developing specifications and special provisions for incorporating recycled materials into construction projects.
• Developing and tracking test applications of recycled products and materials to document product effectiveness relative to standards for highway performance and environmental acceptability.
• Investigating and implement economically viable opportunities to reuse and recycle solid and hazardous waste generated by routine operations such as waste oil, street sweepings, catch basin cleanings, tires, construction and demolition debris, special waste, scrap metal and wood waste.
• Active participation of the Research Needs Committee to identify potential programming and funding opportunities; provide input of needed material reuse and recycling research efforts and to keep up to date on new recycling and reuse technologies, regulations and activities successfully utilized by industry and other state transportation departments. working with state agencies and other organizations to develop training and educational workshops on the use of recycled materials.
• Actively participating with state and federal regulatory agencies on Beneficial Reuse policies.

Mass Highway also initiated a Pollution Prevention Task Force (PPTF) as part of the Environmental Management System Implementation Plan to reduce risk and improve the overall environmental quality at Department facilities through toxic use reduction. The PPTF is comprised of District HazMat Coordinators and other Environmental personnel who cooperate with District Operations personnel in leading pollution prevention efforts for maintenance facilities.

Mass Highway prepares an annual recycling report to meet the requirements of the Commonwealth of Massachusetts' 2000 Transportation Bond Bill (Chapter 235 of the Acts of 2000) and define Mass Highway's accomplishments in terms of recycling, environmentally preferable procurement, and pollution prevention; to discuss and promote ongoing projects; and to establish goals for the coming years. [N] In 2000, Mass Highway recycled more than 15,000 tons of waste and used more than 111,000 tons of recycled materials in construction projects. The agency spent nearly $27 million on recycled-content and environmentally preferable materials and products, considered an economic boon for the state. In 2000, Mass Highway attained an overall recycling rate of 76 percent by recycling more than 15,000 tons of its own waste stream, a 10 percent increase over the previous year and more than double that accomplished by municipalities. Waste materials recycled include antifreeze, construction and demolition debris, street sweepings, and tires.

The majority of MHD's waste stream is composed of materials collected from the State's highways and stored at its depots. This includes everything from street sweepings, to construction and demolition debris (C&D), to tires. After being transported to MHD's depots these materials are segregated for future reuse, disposal, or recycling. Segregation ensures greater recyclability and less processing of these materials by reducing contamination. The most prevalent (and problematic) materials collected by MHD are street sweepings, C&D debris, and catch basin cleanings. Materials such as asphalt, brick, and concrete (ABC), and scrap metal have significant value and well-developed markets and are easier to recycle. In 2000, nearly 16,000 tons of waste materials including ABC, C&D, scrap metal, street sweepings, wood, and yard wastes & leaves were collected and stored at MHD depots. Close to 15,000 tons of these materials were recycled. Over 90 percent of the over 300 tons of automotive related waste products created at MHD depots is recycled. Office wastes created by MHD's six offices are typical and include paper, paper products, and toner cartridges. Mass Highway counted 15.75 tons of paper recycled, reaping energy savings of 161 million BTU's or emissions savings of 12 tons of carbon dioxide.

Mass Highway tracks agency performance by the percentage recycled in different waste type categories: [N]