| Abstract |
The Watkins-Johnson site is an active research and development, manufacturing, and industrial complex in Santa Cruz County, five miles north of Santa Cruz, California. The Watkins-Johnson Company has owned and operated the complex since 1963, conducting such activities as: metal machining, degreasing, metal plating, and photo laboratory activities. During these activities, a variety of organics, inorganics and metals were used. The primary contaminants of concern affecting the soil and ground water are VOCs including PCE and TCE, and metals including silver. The selected remedial action for the site includes soil vapor (vacuum) extraction with pretreatment of extracted vapors using GAC prior to ambient discharge; capping and grading contaminated soil areas to minimize the potential for mobilization of soil contaminants to the ground water; installing infiltration leachfields to prevent offsite migration of ground water contaminants in the perched zone; installing gravity drains to transfer the contaminated ground water from the perched zone to the regional aquifer zone for subsequent extraction; ground water pumping and onsite treatment to remove contamination from both the perched and regional zones using GAC adsorption with offsite regeneration of spent carbon. The estimated present worth cost for this remedial action is $2,156,243, which includes an estimated annual O and M cost of $167,820. |
