Exhibit 11.1 CLEAN HARBORS, INC. AND SUBSIDIARIES COMPUTATION OF NET INCOME PER SHARE FOR THE SECOND QUARTER ENDED JUNE 30, 1994 (in thousands) Three Months Ended Six Months Ended June 30, June 30, ------------------ ------------------ 1994 1993 1994 1993 ------ ------ ------ ------ Net income $1,251 $1,440 $1,848 $2,275 Less preferred dividends accrued 112 100 212 150 ------ ------ ------ ------ Adjusted net income $1,139 $1,340 $1,636 $2,125 ====== ====== ====== ====== Earning per common and common equivalent share: Weighted average number of shares outstanding 9,429 9,417 9,428 9,393 Incremental shares for stock options under treasury stock method 225 792 252 797 ------ ------ ------ ------ Weighted average number of common and common equivalent shares outstanding 9,654 10,209 9,680 10,190 ====== ====== ====== ====== Net earnings per common and common equivalent share $ .12 $ .13 $ .17 $ .21 ====== ====== ====== ====== Earnings per common and common equivalent share - assuming full dilution: Weighted average number of shares outstanding 9,429 9,417 9,428 9,393 Incremental shares for stock options under treasury stock method 256 792 255 797 ------ ------ ------ ------ Weighted average number of common and common equivalent shares outstanding - assuming full dilution 9,685 10,209 9,683 10,190 ====== ====== ====== ====== Net earnings per common and common equivalent share - assuming full dilution $ .12 $ .13 $ .17 $ .21 ====== ====== ====== ======