KRC Questions Use of Crushed Limestone As Drainage Layer In Landfill Posted: December 8, 2005
To: Ron Gruzesky
Scott R. Smith
Dear Ron and Scott:
It has come to my attention that the drainage layer for the newly-constructed Hopkins County Regional Landfill is composed of crushed limestone. To the extent that this is accurate, I am writing to express my concern with the use of such material in a drainage layer for a mixed municipal waste landfill, due to (a) the potential for physically compromising the underlying liner due to the physical structure of the limestone, depending on the size and characteristics of the material, and (b) the significant possibility that the limestone will react in the presence of acidic leachate and will "set up" and fail to fulfill the intended function of "removing leachate from the top surface of the low permeability solid component, and conveying it to a collection point."
401 KAR 48:080 Section 6 (3) requires that the "physical and chemical properties of the granular material and pipe shall not be adversely affected by the loads or leachate generated by the operations of the landfill." The experience of the Tri-Community Landfill in northern Maine suggests that limestone aggregate is an inappropriate material for use as the drainage layer because it will be adversely affected by the interaction with leachate and will tend to set up. Within a few months of completion of the Tri-Community Landfill, according to Civil Engineering Applications of Scrap Tires: An Emerging Market, (Humphrey and Blumenthal), a drainage layer of limestone-derived sand had hardened into a concrete-like mass that failed to function to convey leachate.
To the extent that limestone aggregate has been used, it would appear that 401 KAR 48:080 Section 6 would require that the material be removed and replaced with an aggregate or other material that is physically and chemically suitable to the intended function and will remain so over time. I would request your consideration of this matter and resolution of same before renewal of the construction permit and issuance of an operational permit.