Bosses of two firms have pleaded not guilty to alleged environmental offences, which could cost the parties a total of £225,000.
William Butterworth, 69, a director at Land Network (Gainsborough) Ltd, is being charged with mixing hazardous waste at a site at Sturgate Airfield, in Upton near Gainsborough.
The Wiltshire man also faces two charges of contravening the requirements of an environmental permit.
Composting business Land Network (Gainsborough) Ltd is facing the same three charges.
Prosecutors from the Environment Agency said the total maximum fines for the alleged offences could be £105,000 for the company and the same amount for Mr Butterworth.
Sheffield-based Lincoln Electric (UK) Ltd faces a charge of depositing welding rod and drawing soap waste without a permit.
It also faces two charges of handling and transferring waste without taking reasonable measures.
If found guilty, the firm could face fines totalling £15,000.
All three parties entered not guilty pleas at a Lincoln Magistrates' Court hearing on Monday, July 2.
The case has been adjourned until a two-day summary trial on October 29 and October 30.
Experts will give evidence on whether the waste materials in question were hazardous or not.