Reconcile opening and closing stocks, receipts, consumption, outputs and losses. Each figure must be traceable to source records. This quantitative check is distinct from the mass balance chain of custody model.
What is a volume reconciliation?
A volume reconciliation checks whether material flow data is consistent. At its simplest, it should link the material available during a given period to production, losses, waste and changes in inventory.
In practice, the reconciliation may cover several material types, multiple production lines, transfers between warehouses, subcontracting, internal regrind and the sale of material without further processing.
Volume reconciliation and the mass balance chain of custody model
These concepts are sometimes confused. Volume reconciliation asks whether actual quantities of inputs, stocks, consumption, outputs and losses form a coherent whole. The mass balance model is a separate way of managing a specified characteristic within a chain of custody.
In RecyClass schemes concerned with physical traceability, the actual presence of recycled material and controlled blending in a known proportion are particularly important.
Which data should be prepared?
- opening and closing inventory;
- purchases and other material receipts;
- raw material consumption in production;
- quantities of products or output materials produced;
- process losses, waste and by-products;
- internal regrind and material returned to the process;
- transfers between sites and warehouses;
- subcontracted operations;
- sales of materials and products within the scope.
How does the auditor assess reliability?
The figures must be linked to source evidence. Data should come from the ERP system, warehouse documents, invoices, weighing records, production reports, recipes or other reliable records used by the organisation.
The auditor may sample periods, materials or products and check whether the figures in the reconciliation can be reproduced from the source documentation.
Discrepancies in Recycling Process
The RecyClass Q&A states that an RP balance discrepancy above 5% requires justification for flows that cannot be measured directly, such as moisture or gases. Omitting measurable streams, such as rejects or fines, is a non-conformity and cannot be resolved with a descriptive explanation alone. The 5% threshold is not general permission for traceability gaps or arbitrary losses.
Common errors
- omitting inventory changes;
- failing to separate PCR and PreCR;
- treating internal regrind as a new source of recycled material;
- omitting losses or by-products;
- using different units of measurement in source systems;
- excluding transfers between sites;
- leaving differences between production reports and sales unexplained.
How should the balance be prepared for an audit?
Start with a map of the physical material flow and then assign a data source to each stage. The spreadsheet then becomes a summary of the system actually operating at the site, rather than a separate document created only for the audit.
Key takeaway
A useful volume reconciliation shows both whether the figures agree and whether the origin of every figure and the fate of the material can be explained reliably.