By John Hambrose

Alliance Landfill's primary property includes 742 acres on the western side of the Lackawanna Valley in a region known as the "Northern Anthracite Field" of Northeastern Pennsylvania. This includes land in three municipalities: Taylor Borough, Old Forge Borough, and Ransom Township in Lackawanna County.

Beginning in the mid-nineteenth century, the property was the site of extensive deep coal-mining activities that resulted in the clear-cutting of the mountainside for mine timbers and extensive mining-related subsurface disturbance. Early in the twentieth century, deep mining was replaced by strip-mining activities that continued for a number of decades and left the Alliance property and much of the local landscape looking like what more than one long-time resident describes as "the surface of the moon." During the 1960s, the pits left behind by strip-mining on Alliance's eventual property were used for municipal waste disposal—without the benefit of the engineered liners, caps, gas collection, and the environmental controls and monitoring employed today.

The "dump" stopped operating in the 1970s. Private development of today's modern, lined-and-capped landfill began in the mid-1980s. The property was purchased by USA Waste in 1996, which merged with Waste Management, Alliance's current operator, in 1998.

Alliance's design and construction in many ways responds to the local topography and the property's historic use. Since its development in the mid-1980s, design of the landfill's cells has been preceded by extensive review of old mine records and subsurface analysis conducted through test borings. This information is used to determine areas of the landfill's liner that require installation of Tensar bi-axial geo-grid to provide additional support in the event of a minor subsidence. Areas that offer a risk of greater subsidence are flushed to the Pennsylvania Department of Environmental Protection Bureau of Mines and Reclamation standards before liner construction begins. In areas where cell excavation encounters coal, the coal is over-excavated to a minimum of 25 feet below liner grade and the pit is then backfilled with engineered fill.

Alliance's state-of-the-art design employs a double-liner system with 100-mil HDPE geomembrane primary and secondary liners—each equipped with dual protective non-woven geotextile layers and two pipe-equipped gravel wastewater collection zones. Alliance's newest cells include a clay-and-fabric Bentofix layer under the primary liner system. The first layer of waste placed on a new liner is hand sorted. Large objects are removed to prevent the possible puncture of the primary liner.

PHOTO: WASTE MANAGEMENT

Once a disposal area is filled to capacity, it is covered with a 40-mil LLDPE cap that has a protective non-woven geo-textile layer below and a FabriNet layer above to allow stormwater and snowmelt drainage. A 2-foot layer of processed soil, with a 6-inch upper layer of soil and Grade A biosolid fertilizer, is placed on the cap and fertilized, seeded, and mulched. All of the synthetic materials used in construction of Alliance's liner and cap are manufactured and installed by GSE Lining Technology Inc.

Alliance operates 254 vertical and lateral landfill gas collection wells. The wells use perforated 6-inch PVC or HDPE pipe that, in capped areas, are sealed to the cap with an airtight boot. Each well is equipped with a regulator valve and several measuring ports that are used to monitor LFG flow and quality. A length of flex pipe is used to connect the wellhead to collector lines. The system also collects gas from the wastewater collection system and ties into Alliance's LFG system "loop." The loop allows Alliance to maintain negative pressure on all wells in the event of a blockage or localized system failure. Collector lines that are not underground are insulated or equipped with heat-trace sleeves that are operated during cold weather. This prevents the collector lines from becoming scaled with frozen condensate that can result in ineffective LFG collection and gas-related nuisances. Alliance's gas is destroyed in one 5,000 cfm John Zink flare, two 4,000 cfm LFG Specialties flares, and one 1,600 cfm LFG flare. The landfill is developing opportunities that will result in its gas being used to generate green energy off-site. Alliance's LFG system collected an average 6,973 cfm of gas through the first 28 days of March 2005.

The waste area system relies on a GPS-equipped bulldozer and an office computer equipped with Carlson Software to track ongoing disposal operations. Updating in milliseconds, the system reports the location of the bulldozer to a computer that plots the3D-construction of the landfill. This information allows site engineers to track waste compaction rates and the growth of the landfill, and assists in the design of future disposal areas. Alliance also uses a "roving" GPS unit that is employed in general construction applications, including monthly waste-compaction assessments, completion of as-builts, plotting utility locations, and profiling slopes. Data collected by both GPS systems is fed into Alliance's CAD system, which is used by a number of site engineers. The use of these systems saves Alliance between $80,000 and $100,000 in avoided surveying costs.

Alliance operates about 7,000 feet of permanent and portable line sprayers as its first line of defense against odor nuisances. This system is often operated with clean water but on occasion unscented odor neutralizers manufactured by GE Water Technologies, Benzaco Scientific Inc., and Enzymatic Odor Solutions Inc., are used to provide additional odor control. The wastewater plant uses an aerobic system to control odors. Application of treated wastewater with neutralizer at the landfill's working face, continuous application of daily cover, and the vigilant management of the gas collection system also minimize the potential for odor nuisances.

The base grade of Alliance's liner has a general correspondence to the local topography. Anchor and toe trenches are constructed to secure the liner in place and Alliance's disposal "lifts" are terraced for stormwater control and to assure stability of the completed landfill.

The character of the landfill's subsurface hydrology is dominated by the region's vast "mine pool" created when the area's labyrinth of underground mines was flooded decades ago.

Waste Management's First ISO 14001 Landfill
Alliance Landfill in November became the first of Waste Management's 289 operating landfills (and to our knowledge only the sixth in the US) to receive International Standards Organization 14001 certification for quality and environmental standards. With ISO-compliance audits conducted every six months by Lloyd's Register of Quality Assurance—the most rigorous audit schedule ISO allows—Alliance is continually reviewing and improving its environmental management system. ISO certification is an added assurance to the landfill's neighbors, employees, and regulators that its operations meet or exceed all compliance requirements and its practices and procedures are unsurpassed in the industry.

Alliance's ISO 14001 certification followed a one-year process in which landfill employees and consultants from Gannett Fleming reviewed all of Alliance's environmental control policies and procedures and rewrote those that did not meet ISO 14001 standards. At the conclusion of this review and realignment, an auditor for Lloyd's Register of Quality Assurance reviewed Alliance's new environmental management system. Alliance received its certification at the completion of this review and passed its first six-month ISO 14001 audit with high marks.

John Hambrose is the community relations coordinator for Alliance Landfill.

MSW - September/October 2005