Pump Lift Station Aids Tank Terminal Remediation Project

International-Matex Tank Terminals (IMTT) is a leading provider of bulk liquid handling services. The company operates 10 tank terminals in the United States and Canada, all located near major distribution centers. IMTT is one of many smaller tank companies operating as bulk liquid storage terminals. The tanks are available to wholesalers looking to store a variety of liquids, from alcohols to chemicals to vegetable oil.“Think of us as a public storage company,” says Gregory N. Wees, Engineering, Maintenance & Computer Systems Manager at IMTT’s Richmond, CA, tank terminal. “We offer rental space here.”

The 25-acre Richmond site, located along a deep-water tanker berth on the east shore of San Francisco Bay, includes 46 tanks ranging in size from 10,000 gallons to 100,000 barrels, with a total capacity of 670,000 barrels. The tanks meet all standards for emissions, spill control and inspection compliance.

Site Remediation

An innovative remediation project on the site uses cutting-edge techniques to ensure the site meets state and federal environmental regulations. To prevent existing in-ground contaminants from flowing into the bay, the IMTT remediation project seals the site so all groundwater can be collected and filtered. The Walnut Creek, CA, office of MWH provided engineering services to IMTT.

After considering alternatives, engineers chose a hydraulic barrier around the site, coupled with groundwater collection, pumping and filtration.

The project features a two-foot-wide slurry wall constructed by Remedial Construction Services LP (RECON). The wall reaches down into a clay layer between 5’ and 10’ below surface grade. The combination of the impervious clay base and slurry wall contains all precipitation within the tank terminal site.

The Pump Station

To capture the surface water, the entire site is sloped to a drain that flows into a pre-engineered lift station supplied by Romtec Utilities. The lift station features a 6’ diameter concrete wet well, equipped with two submersible pumps. The contaminated water draining into the wet well is pumped through valves into a holding tank and oil-water separator, where contaminants are removed before being discharged into the bay. Sonnikson & Stordahl Construction Inc. of Martinez, CA, installed the lift station and provided all related concrete and mechanical construction.

One of the options considered by IMTT was the traditional system of site lining. For this method, it would have been necessary to excavate the 25-acre site to a depth of 4 inches, and then bury a thick plastic cover at that depth. Complicating that alternative was a network of above and underground piping that makes digging difficult.

“It would have cost about a third more to install the liner than to do the slurry wall-pump station,” Wees says. “And there would have been a lot more maintenance, since the liner is prone to tearing.”

The lift station and oil-water separator system is operational. “It works better than I thought it would,” Wees says. “The lift station went in on time and works very well.”