PIVOX Corporation served as construction contractor for soil remediation and site restoration at PG&E’s former Santa Cruz Manufactured Gas Plant (MGP) site. This project is one of 20 MGP remediation projects successfully completed by PIVOX for utility clients throughout California.
The former Santa Cruz MGP site is located within an active commercial development in busy downtown Santa Cruz. Remediation activities consisted of soil excavation using slot trenching, large-diameter augers, hand excavation, mechanical excavation to depths of up to 14 feet below ground. Slot trenching was conducted along the project boundary, adjacent to sidewalks and at the toe of an adjacent hillside. Approximately 6,000 tons of soil was excavated and disposed at off-site landfills. Following the excavation and backfilling, the parking lot, driveway, hillside retention wall, and landscaped planter areas were replaced to pre-existing conditions.
The site’s busy urban setting, tight excavation constraints, and protection of the public were the critical factors for success of this project. PIVOX’s surgical construction approach, expertise in multiple excavation methods, and emphasis on public health and safety were instrumental in completing the remediation efficiently with no impact to the public.
PIVOX developed a phased construction task sequence and workflow that maintained customer/tenant parking at the active commercial development at the site while isolating the public from construction hazards. As work progressed, PIVOX reconfigured public vehicle access, public parking, and construction vehicle access to best fit the work, maintain public access, and reduce safety risks to workers and the public. PIVOX also identified a nearby empty lot for use as a temporary equipment staging yard and soil import/disposal truck staging location. This provided an area for soil haul trucks to wait for single-truck access to the site for soil loading or delivery, preventing trucks from lining up on the busy public road and impacting traffic.
During construction, PIVOX employed extensive noise, dust, and odor control practices to protect worker health and prevent any nuisance or hazards to the public and provided full-time dedicated personnel (with no other production responsibilities) to monitor and maintain these measures during all construction activities. In addition, the close proximity of residences, businesses, and an immediately adjacent hillside required PIVOX to develop and implement strict vibration control and monitoring measures. PIVOX worked with the project engineer to develop a vibration monitoring process and developed a backfill approach that allowed PIVOX to avoid the use of vibratory compaction equipment during backfilling.