An operator which receives notification under § 725.407 shall, within 30 days of receipt, file a response indicating its intent to accept or contest its identification as a potentially liable operator. The operator's response shall also be sent to the claimant by regular mail.

If the operator contests its identification, it shall, on a form supplied by the district director, state the precise nature of its disagreement by admitting or denying each of the following assertions. In answering these assertions, the term “operator” shall include any operator for which the identified operator may be considered a successor operator pursuant to § 725.492.

That the named operator was an operator for any period after June 30, 1973;

That the operator employed the miner as a miner for a cumulative period of not less than one year;

That the miner was exposed to coal mine dust while working for the operator;

That the miner's employment with the operator included at least one working day after December 31, 1969; and

That the operator is capable of assuming liability for the payment of benefits.

An operator which receives notification under § 725.407, and which fails to file a response within the time limit provided by this section, shall not be allowed to contest its liability for the payment of benefits on any of the grounds set forth in paragraph (a)(2).

Within 90 days of the date on which it receives notification under § 725.407, an operator may submit documentary evidence in support of its position.

No documentary evidence relevant to the grounds set forth in paragraph (a)(2) may be admitted in any further proceedings unless it is submitted within the time limits set forth in this section.