Final Closure of a Paper Mill Landfill Using Water Balance Design Concepts and Pimary Clarifier Sludge as a Final Cover, 1998 Environmental Conference Proceedings

Ted A. Shreve

Mead Specialty Paper

G. David Garrett, P.G., Principal

Gregory N. Richardson, Ph.D., P.E.

G.N. Richardson & Associates

A 28-year old paper mill landfill in western Massachusetts was closed in 1997 using the mill’s own wastes as final cover materials. This final cover design differs from conventional landfill covers because the infiltration barrier on the side slopes was constructed with a soil-like paper mill primary clarifier sludge, compacted to meet the necessary permeability requirements, in lieu of using compacted clay and/or geosynthetic barriers. The permeability of the sludge varies on the order of 10 -5 to 10 -6 cm/sec when lightly compacted. Water balance concepts were used to demonstrate to the regulatory agency that these permeability values, which are higher than what is typically required for compacted clay barriers, are sufficient to limit post-closure infiltration on side slopes to acceptable values (less than 3 percent of the total precipitation, in this case), when used in conjunction with a sufficiently thick (30 cm) vegetative support layer. A conventional PVC flexible membrane and synthetic drainage media were used to limit infiltration on the flatter landfill cap, but this covers a relatively small surface area. Then, a composted blend of primary clarifier sludge, food wastes and animal manure was substituted for topsoil over the entire landfill.

The beneficial use of non hazardous paper mill wastes is gaining acceptance as an alternative to landfill disposal within the pulp and paper industry and in the regulatory community. This project turned several unique waste products into viable landfill final cover material, which has long reaching implications for closure of industrial and municipal landfills, and the pulp and paper industry as a whole. Paper mill wastes have been demonstrated to serve as a suitable soil substitute, in addition to a soil enhancement. The multitudes of public and private solid waste landfills throughout North America provide long-term opportunities for application of paper mill wastes as a soil substitute. Outsourcing to an agribusiness composting operation provides this mill with a long-term alternative to land filling, which reduces future disposal costs and creates new outlets for beneficial use of the waste. This project not only conserved both land and material resources, the project owner estimates that the water-balance final cover design saved the company over $2M in final closure costs, relative to estimates for a traditional cover.