A grave 'liner' is a cover with no base that is placed over the lowered casket before the grave is filled in with earth. A burial 'vault' differs in that it is a complete and sealed unit.
With a grave liner, the only place the casket touches the earth is at its base when it is placed in the ground. The casket is lowered into the grave and the grave liner is placed over the casket at which point the liner is covered with earth and natural turf is rolled back over the grave site once it has settled to the liner. A headstone of the size and shape dictated in the cemetery bylaws may then be placed at the head of the grave site. Natural decomposition is greatly delayed when a grave liner or burial vault is employed. There's a website called Funeral Management Flash Cards that states the two main purposes of outer burial containers is to "Support earth load, and Limit the intrusion of outside elements." This is the exact opposite of what is intended with a green burial where we are choosing to return our bodies to the earth.
As with most municipal cemeteries in BC, The City of Williams Lake Cemetery Bylaws state that: A fiberglass grave liner shall be used for each interment, except in the case of cremated remains interred according to Section 29(e).
A Canadian company that makes these 'butter dishing' products describes their fiberglass grave liners as having a 100-year warranty.
The site description states that their Fiberglass liner
Non-porous – water resistant
Excellent cold weather performance
Prevents burial site from sinking
Independently tested to withstand 18,000 pounds top load pressure Computer designed and engineered
Vault base available for a 2-piece sealed unit
Lightweight and stack-able, easily installed, and have superior strength."
Why are grave liners used?
In a conventional cemetery, it is important to keep the grounds level so that grave sites are not sinking as they will naturally when a body is interred without a liner or vault. You will often see fresh natural burial sites with a big mound of earth over the grave. This is to allow for some natural sinking of the grave site and in time the natural grasses and wildflowers will make the burial almost indistinguishable from the surrounding woodlands. Grounds in a conventional cemetery have standards of uniformity and must be maintained in a manner that is acceptable to what the public expects.
Cemetery grounds are like well kept urban yards; grassy, irrigated and mowed. You don't want your mowing machine sinking when it passes over Grandpa's grave site. Weeds are eradicated and headstones are uniform as dictated by cemetery regulations.
In a Green Burial, the bodies of our beloveds are gently returned to the earth wrapped in a shroud, or in a simple pine box or willow casket, all of which decompose naturally and relatively quickly. Green Burials are usually a shallower depth than conventional burial.
With a Green Burial, there is no embalming which is another deterrent to decomposition, no metals are used in the casket and a green burial cemetery will not be fertilized, mowed or chemically managed for weeds.
Ideally, a Green Burial Cemetery will be a Conservation Burial Ground where our dead bodies are allowed to return naturally to the native woodlands they inhabit.
Q. What about inverting the outer container?
A. Called ‘butterdishing’, this method may allow the body to be closer to the earth on the bottom surface, but still impedes and puts non-biodegradable artifacts in the ground. It is not an acceptable alternative to going without.