National Response, a portfolio company of J.F. Lehman & Company, has completed its buy of OP-TECH Environmental Services. OP-TECH provides specialty environmental remediation and industrial services in the Northeast and Mid-Atlantic regions of the U.S. It will enhance the service portfolio of National Response, which provides regulatory compliance and emergency response services connected with the U.S. Oil Pollution Act of 1990. Senior debt financing was arranged by BNP Paribas Securities.