Once again MSW Management is proud to pay tribute to SWANA’s Landfill Excellence Award winners.

By John Trotti

Gold Award:
Outer Loop Recycling and Disposal Facility, Louisville, KY

For approximately 35 years, the Outer Loop Recycling and Disposal Facility (Outer Loop) has served as a solid waste disposal site. Located in Jefferson County, Louisville, KY, approximately 9 miles south of the Kentucky-Indiana state border, the facility consists of seven individual and separate landfill units (designated as Units 1 through 7). The combined waste footprint is 390 acres and the total facility area is 782 acres. Outer Loop has been owned and operated by Waste Management of Kentucky LLC (WMK), a subsidiary of Waste Management Inc. (WMI), since 1984.

Units 1 through 3 and Unit 6 are filled and final-capped. Unit 4 is permitted as a construction/demolition debris landfill and is active. Units 5 and 7 are permitted as contained landfills and are active.

The site also incorporates a 455-acre wetlands mitigation and banking area, a 40,000-ton-per-year composting operation, a landfill gas-to-energy facility, a sequential batch reactor (SBR) leachate treatment plant, and a petroleum-contaminated-soil treatment area. The design, construction, and operation of this facility exceed industry standards.

The area surrounding Outer Loop is a mix of dense industrial to the north and northwest, commercial businesses to the northwest and southwest, a railroad yard to the west, residential and commercial buildings to the south, and Interstate 65 to the east. There are no known groundwater users within a 1-mile radius of the facility, or any known springs, water supply wells, or water intakes within the vicinity of the site.

Waste materials accepted at Outer Loop include municipal solid waste, construction demolition and debris, special waste, nonhazardous solidified liquid/sludge and petroleum contaminated soil. Between 600 and 700 vehicles deliver an average waste flow of 5,500 tons per day from the Louisville metropolitan area and 22 surrounding counties in Kentucky and Indiana. It is the largest operating Subtitle D landfill in Kentucky, and provides waste disposal service for residential, commercial, and industrial customers.

As of March 2005, Outer Loop has about 40.9 million cubic yards of remaining gross airspace. At an anticipated disposal rate of 1 million tons per year, the landfill has about 35 years of total remaining permitted disposal capacity. With the use of bioreactors in new cells it is thought this will expand to at least 40 years.

Daily site operations at Outer Loop are the responsibility of the landfill operator/manager, Rick Barr. He is supported by other state-licensed operators and managers including Kevin Brown, Chad Abell, Dave Dunn, and Charles Dyer. Kevin Mieczkowski is responsible for the composting facility operations.

Bioreactor Research
Outer Loop is the site of an on-going multi-year bioreactor research project conducted by WMI, in collaboration with the EPA, through a Cooperative Research and Development Agreement (CRADA), and the Kentucky Department of Environmental Protection (KDEP). The facility was selected because of several favorable characteristics, including adequate acreage and working space, average US climatic conditions, permit conditions, and the opportunity for coordination with other agencies. Filling activities in the bioreactor cells commenced in 2001.

The landfill research project is both unique and significant due to its examination of emerging technologies with testing and research variables at the field-scale level.

There are currently two bioreactor studies and one biocover study being conducted at Outer Loop. These include

• The “retrofit” Facultative Landfill Bioreactor (FLB) study—being performed within a 47.7-acre area within the western part of active landfill Unit 5. Waste in these cells is 4 to 5 years of age.
• The “as constructed” Aerobic-Anaerobic Bioreactor (AALB) study (patent number US6,283,676,B1)—being performed within active Unit 7
• The Biologically Active Landfill Cover (BALC) study—being performed in Units 5 & 7.

The FLB study evaluates the feasibility of controlling ammonia in leachate by injecting nitrate-containing leachate. This is important in that elevated ammonia requires treatment before discharge to the environment or a treatment plant. It is the only project of its kind in the US.

The FLB Study objectives are to measure under field-scale conditions (1) the effect that adding nitrate-containing leachate to existing landfill waste has on the rate and extent of waste stabilization and the nitrogen cycle, (2) the extent that denitrification occurs in the landfill environment, and (3) the impact that operating an FLB has on atmospheric emissions.

Facultative Bioreactor Test Cells
To facilitate the FLB study, Unit 5 was designed and constructed with the approval of the Kentucky Department for Environmental Protection (KYDEP) and the EPA. The design and construction of Unit 5 was uncommon when compared to the traditional Subtitle D landfill and posed unique advantages and difficulties to overcome during the FLB Study, as summarized below.

• The SBR for removing the ammonia was about 1 mile from the test cells and four easements had to be acquired prior to construction.
• The site contains asbestos, and special care had to be taken during construction and drilling.
• While the property is around 47 acres, only about 8 acres are at level ground. Much of the trenching had to be put on the slopes. Because of this, the trenches had to be very deep to prevent liquid breakouts.
• Discharge of the SBR is a batch process that happens infrequently, but over a relatively short period of time.

Six vertical gas extraction wells were constructed in the cells. The gas wells serve the dual purpose of collecting landfill gas and penetrating layers of soil cover placed during landfilling. Probes for measuring waste moisture, oxidation-reduction potential, and landfill gas were installed during gas well construction. Similar installations were made for the control cells located in Unit 7, Cell 3A, and Unit 7, Cell 3B. After treatment in the SBR, leachate is distributed into the tanks on top of Unit 5 and then by gravity into the array of trenches.

Preliminary FLB Results—To date, an average of 50,000 gpd of liquid can readily be added to the retrofit bioreactor. The site has experimented with adding as much as 100,000 gpd and is also able to take experimental commercial liquids from off the property. WMI believes this is very unique in the solid waste industry.

This bioreactor process involves specialized construction and management techniques for measuring and controlling the amounts of water and air in the landfill, as well as extensive data collection and analysis.

Innovation and Creativity
Outer Loop is one of only a handful of US landfills conducting concurrent full-scale operations and research and development. The WMI bioreactor program is recognized as setting a standard in the landfill industry and the Outer Loop site is where most of the WMI research is taking place. Just to recap, Outer Loop research and study efforts include

• Accelerating the methane generation so as to make the LFG energy from solid waste more available than would otherwise be the case with conventional LFG collection.
• Reducing uncaptured, fugitive air emissions associated with landfills through trial covers, including leaf/mulch compost.
• Achieving stable landfill conditions more quickly than conventional means, particularly prior to closure.
• Reducing global warming by beneficially using the collected methane and reducing fugitive emissions.
• Extending the lifespan of the existing landfill cells without increasing their size.

In addition, Outer Loop’s project is already delivering economic and waste recycling benefits. Several landfill cells have re-used well over a million shredded waste tires in trials as leachate collection media. Increased landfill gas generation is captured with onsite wells delivering a total of more than 1.1 trillion cubic feet of gas to GE’s Appliance Park Facility, where the LFG is used in place of conventional fuels to provide steam and heat. Landfill gas is also being sent to nearby Gohman Asphalt, which is currently using the LFG as its primary fuel.

Clearly, the most unique aspect of the site is working for the last four years with the EPA under the CRADA, as discussed previously. This cooperative approach ensures that the resultant research and data will be released to the landfill industry and be realized as a public benefit.

In addition, the progress of this research has been reported at several SWANA symposiums, and the respective SWANA technical division members (i.e., Landfill Management and Landfill Gas Management) are tracking and evaluating this progress. Not only are the Outer Loop research concepts timely, they each have the potential to make landfills more environmentally protective and operationally efficient in the future. The Outer Loop facility also provides an example for the industry on how to conduct needed research at the field-scale and demonstration-scale while operating a large landfill site.

As Kentucky and other states face the challenges associated with the cleanup and remediation of old abandoned landfills, bioreactor landfill technology like that being pioneered at Outer Loop may provide a key to promoting improved solid waste design and disposal techniques for yesterday’s and today’s landfills—offering significant environmental and economic benefits in the years to come.

Silver Award:
Hartland Landfill, Victoria, BC
Hartland landfill is owned and operated by the Capital Regional District (CRD) and is located about 14 km northwest of Victoria. It is the only solid waste disposal facility in the Capital Region, serving 340,000 people. Hartland receives about 140,000 tons of municipal solid waste per year. The operation is a multi-purpose facility providing recycling, HHW collection, a salvage area, yard and garden waste collection and processing, and controlled waste disposal and landfill service to commercial and residential customers. Since 1985, over $30 million has been invested in capital works, environmental controls, and general site improvements, and the site is now run as a state-of-the-art facility.

Hartland has two phases: Phase 1 is closed, having received 4.5 million m3 of refuse, and Phase 2, with a capacity of 10 million m3, is expected to last until 2048. Phase 1 closure took place in 1997 and consisted of an impermeable engineered cover designed to control surface water runoff while preventing further production of leachate. Phase 2 has been designed with a unique leachate management concept specific to the hydrology of the area. The bottom of the Phase 2 area is a former lake basin that acts as a sump with an inward flow of ground and surface water. Leachate is collected in the sump and drained through a microtunnel to the lower leachate lagoon. The water table surrounding the basin is naturally higher than that of the sump, forming a hydraulic trap ensuring leachate is contained within the basin area. An extensive groundwater and surface water monitoring program costing $400,000 per year is in place to ensure no leachate exits the site.

A comprehensive landfill gas collection and disposal/utilization facility manages 650 scfm of landfill gas. The system consists of a collection network, 115 horizontal and vertical wells, a ground flare, and a 2-MW utilization facility commencing operation in 2004. There is a potential recovery rate of between 1,600 scfm to 1,800 scfm in the future. Gas collection and utilization costs are in the order of $5 million.

Ongoing short- and long-term planning is essential, considering that the $12 million revenue generated from tipping fees supports the programs of the entire solid waste division. Financial modeling is used to assess the impact of waste diversion programs on the division and disposal fees are adjusted accordingly to ensure that long-term stability and appropriate levels of service are maintained. Along with financial planning, program performance indicators are tracked to ensure that the entire divisional operation is cost-effective. The CRD solid waste function is the only agency in British Columbia that has zero requisition for all solid waste activities.

A public outreach program promotes community relations with the neighbors around the landfill and educates the community at large about solid waste operational and diversion practices. This outreach program—including a good neighbor policy, site tours, and environmental education—forms part of the division’s information strategy.

Site Development
Hartland landfill has grown to be a multi-purpose facility providing service to residential and commercial customers. In addition to the landfill there are four distinct areas: (1) recycling and household hazardous waste drop off, (2) yard and garden waste disposal, (3) residential refuse bin drop off, and (4) controlled waste disposal. There are also facilities that support the administrative function of the operation such as a weigh scale, administration office, and various operations buildings.

Controlled wastes are those that, because of their inherent nature, need to be handled in a controlled manner and away from the other disposal areas. These include liquids, animal carcasses, solids, semi-solids, special waste (asbestos), and contaminated soil. Customers require an appointment and a permit to deliver these wastes, which a landfill attendant monitors. The area is constructed of clay cells on top of the landfill and receives about 3,000 tons of waste per year.

The landfill has been developed as two operational areas, Phase 1 and Phase 2. Phase 1 is now closed and Phase 2 began operating on April 30, 1997.

The Phase 1 area was the original landfill of approximately 20 hectares and had been in operation since the early 1950s. The site was not an engineered landfill and “just happened” like many dumps. Recognizing the significant impact of a site of this nature, steps were taken beginning in 1984 to put in place environmental controls.

The Phase 1 landfill was closed in 1997 with an engineered cover consisting of aggregates, compacted clay, a PVC membrane and a topsoil layer. The cover system was designed to control surface water runoff while preventing the further production of leachate.

The Phase 2 landfill is an area of about 30 hectares, partially overlapping Phase 1, with a capacity for approximately 8 million tons of refuse. Originally, Phase 2 consisted of a 2.5 hectare lake, which was drained, excavated, and prepared for landfilling. The area surrounding the basin is rugged with rock outcroppings and steep side slopes, which by its very nature promotes an inward flow of surface water toward the basin.

The overall long-term site-filling plan requires approval by the MWLAP. Approval was initially granted in 1987 and has been updated and approved subsequently to include Phase 2. The filling plan firmly establishes the site footprint and projects capacity to approximately 2048; subject to the effectiveness of the region's waste reduction programs on volumes.

A site rehabilitation plan began in 2004, which will blend the site into the surrounding forested area. The end-use will be for an open space/park which will be available after the operational uses have ended (i.e., post-closure monitoring).

A significant landfill gas collection, monitoring, and disposal/utilization program is underway at the Hartland site. LFG production at Hartland landfill (Phase 1 and Phase 2) is estimated to peak at approximately 2,200 scfm with a recovery potential of between 1,600 scfm to 1,800 scfm. A public/private partnership has been undertaken to develop a gas-to-electricity plant. This project is complete and presently being commissioned. The contractor undertook to construct and operate a landfill gas utilization facility by using the gas produced in the landfill. The contractor will pay the CRD a royalty for the energy produced. At the present time, the plant will produce 1.6 MW of electricity, which will be sold to BC Hydro. That is enough energy to supply about 1,600 homes.

Site Operations
This work is administered and designed by the CRD and its consultants, and tendered to/constructed by private contractors. The daily site operation, landfill repairs, and maintenance work are tendered to private contractors.

The landfill operation is divided into two main contracts; the contract to place and compact the municipal solid waste (MSW) received daily and the contract to haul refuse and recycling bins onsite and off-site. At present, the contract to place and compact refuse is about $650,000 per year and the roll-off bin haul contract is approximately $220,000 per year.

Standard refuse is typically landfilled using the advanced terrace method. This technique enables control of surface runoff and leachate flow, as well as control of long-term site settlement. It consists of an advancing active face with vehicular access atop the preceding day’s refuse. Alternatively, depending on site conditions, refuse will be deposited at the toe of the active face and pushed up to the desired elevation. The active face advances in four meter lifts and all refuse is covered daily with aggregate on the horizontal and sloping surfaces. A synthetic tarp serves as nightly cover on the active face.

A supervisory control and data acquisition system (SCADA) is in place to monitor the leachate management system. Leachate levels, pumping cycles, purge well levels and some groundwater levels are continuously monitored and operated.

The system is fully automated and a computer with real-time read-outs is available to office and operations staff to ensure the system is operating as designed.

Site Rehabilitation and Reforestation
A long-standing vision for Hartland landfill is to restore the land to a condition that will blend in naturally with the surrounding forest. A plan has been developed that proposes installing a growing medium over the existing cover system and planting a broad variety of native species of overstory and understory vegetation and ground cover, to provide a self-sustaining natural ecosystem.

Planting began in 2004 and includes Douglas fir, bigleaf maple, and arbutus, as well as ocean spray, Indian plum, and mock orange (all which are native to the area). Over the course of five years, the entire Phase 1 area (approximately 10 hectares) of the Hartland site will be rehabilitated. Over 1.4 meters of topsoil has been placed over the cover material and membrane to allow for root growth.

In addition to this rehabilitation, the Phase 2 area, which is under landfill construction, is being progressively closed as much as possible to enhance landfill gas collection, reduce surface water infiltration (leachate production), and to provide a higher degree of aesthetics. These programs are funded through the annual operating budget.

Bronze Award:
Cedar Hills Regional Landfill, King County, WA
The Cedar Hills Regional Landfill is located near Maple Valley, WA, approximately 25 miles east of Seattle. King County owns the landfill, which disposes of solid waste from all of King County outside of the City of Seattle. Currently, the landfill accepts approximately 3,500 tons per day of municipal solid waste. The site encompasses 940 acres, with 452 acres of interior permitted waste fill area. Waste filling began in an unlined area of the site in the 1960s. In 1985, King County constructed the first composite-lined expansion area with leachate collection. The construction of the area was well ahead of landfill lining and leachate collection requirements imposed by the RCRA Subtitle D regulations of 1991. King County Solid Waste Division (KCSWD) personnel operate the landfill and all of its environmental control systems, including the landfill gas collection system.

Cedar Hills Regional Landfill,, King County, WA

The development of the Cedar Hills Regional Landfill has been planned as a series of large expansion areas, or cells, each designed to provide several years of filling capacity. Surface water runoff is uniquely managed at the site. The layout of the landfill is designed so that surface water runoff from landfill areas that have received final or interim final covers drain to four permanent detention ponds. An additional temporary stormwater detention pond is also constructed with the development of each new cell.

Beginning in the early 1980s, environmental protection was established as a priority at the Cedar Hills Regional Landfill. King County understood the importance of taking all reasonable precautions to prevent groundwater contamination, and effective measures were taken to reduce or eliminate the impacts of past practices on groundwater quality. An example is the improvements made to the “Central Pit,” a 2.1.1-acre (final cover surface) expansion area of the Cedar Hills Regional Landfill. The improvements were designed in expectation of the requirements of WAC 173-304 promulgated in 1984 and enacted in 1986. In 1985, KCSWD constructed a composite lining system (plastic membrane underlain by low-permeability soils) in the Central Pit area. Although earlier parts of the landfill were unlined, the new area in 1985 would be closer to groundwater. Therefore, as final cover was placed over the earlier parts of the landfill, the composite lining was installed in the Central Pit. All successive expansion areas of the landfill since that time have had RCRA Subtitle-D-compliant lining.

Over the years, King County has proactively remediated a number of issues by investing in a large number of improvement projects.

Landfill Monitoring and Inspection Program
KCSWD has a trained staff of four full-time technicians who are responsible for monitoring, inspection, and operation of the environmental control systems at the landfill.

The landfill gas system technicians have implemented an aggressive, day-to-day preventive maintenance program. Inspections occur during monitoring sessions as well as during scheduled quadrant inspections.

The Cedar Hills Regional Landfill gas collection system has (at present) nearly 500 landfill gas collection and control stations. It consists of 276 horizontal gas collectors, 108 vertical gas collectors, 29 migration control vertical wells, and 84 leachate control gas connections

A network of 19 down-gradient wells and 22 up-gradient wells is used to monitor groundwater. An aggressive approach to landfill gas control has prevented lateral gas migration. KCSWD also monitors ambient air and has a complete meteorological station at the site. The Nasal Ranger program is used to monitor odor. KCSWD hired an olfactory certification consultant—Nasal Ranger Inc.—to train all supervisors and leads and landfill gas operators to recognize odors and evaluate the source and concentration levels of reported and detected odors. Design of modifications to the existing gas collection system to provide gas to the generating plant is under way.

Progressive Cover Program
KCSWD has adopted a program of placing interim cover over all areas that will not have final cover immediately installed and will not be covered with additional waste lifts during wet weather months (October through May). This program reduces water infiltration into the landfill and minimizes gas emissions and air breakthrough into the gas extraction system. Final cover is placed progressively as final fill elevations are reached in each cell.

KCSWD has recently implemented a regular Compaction Control Program for monitoring the compaction of recently placed waste in the landfill. This is done through monthly measurement of compaction densities achieved, and adjusting operating practices as necessary to ensure consistency in the resulting densities. In addition, annual evaluation of effective density is completed using aerial photogrammetric and land survey data. The tonnage placed in a defined area, as recorded at the scales and tracked to the working face, is compared to the fill volume in the defined area. The compaction results are provided to disposal equipment operators to provide feedback on performance of ongoing operating methods with a goal of optimizing landfill airspace consumption.

Up-To-Date Technology
KCSWD is an earlier adopter of new landfill technology where the new technology makes economic sense. One example is the Supervisory Control and Data Acquisition (SCADA) system that monitors processes at the landfill as well as at the county’s transfer stations and closed landfills.

ECS Engineering Inc., of Bothell, WA, was responsible for the investigation, study and master plan preparation for the new countywide SCADA system for the KCSWD. The project goal was to develop a SCADA system that would allow staff to monitor sites throughout the Cedar Hills Regional Landfill, remote landfills, and transfer stations for process and security alarm conditions.

Subsequent to the investigation, ECS Engineering worked with the County Information Technology and Communications Departments to investigate communications options to all of the sites. The plan recommended using an existing countywide fiber optic and telephone Ethernet network for most of the locations that needed to be monitored. The remainder of the sites were provided with Ethernet radios, which allowed connection of remote sites to the existing network.

The resultant system configuration recommended to the county is a programmable logic controller-based system, communication over the Ethernet network to a master SCADA computer utilizing operator interface software for data gathering, report generation, alarm generation, and graphic screens for information display. The system has new Allen-Bradley PLCs and a Graphical User Interface/Data acquisition system software. Technical Systems Inc. was the prime contractor and SCADA system hardware supplier.

To monitor all facilities from the Cedar Hills facility, the master SCADA computer communicates with the remote facilities (transfer stations and closed land fills) over a combination of the county’s existing Ethernet network, cellular telephone modem, or leased telephone line. The type of communication selected depended on the most economical (initial and life cycle) option. Specifically, at Cedar Hills all of the potable water pumps, gas flares and blowers, and monitoring sensors in the leachate, stormwater, and gas systems are monitored by a SCADA system that transmits data to the site office through a fiber optic network installed around the landfill perimeter. This network is accessible throughout King County’s Ethernet, including at offsite county offices.

MSW - September/October 2005