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Stanbec Work Plan for Amended Bioremediation Pilot Study BP Terminal 40T November 10, 2008 east-southeast to southeast. The B-zone potentiometric surface is typically 0.01 to 0.5 foot lower than the A-zone water levels, creating a downward vertical gradient of 0.04 to 0.12 ft/ft. BIC Aquitard A low permeability clay-silt aquitard unit separates the B-zone and underlying C-zone. The aquitard varies in thickness from four to 15 ft. Reported hydraulic conductivity for aquitard samples collected in the northern part of the study area range from 0.001 to 0.0001 ft/day (HLA, November 1991). C-zone The C-zone underlies the B/C Aquitard at approximately 45 to 50 ft bgs. The C-zone potentiometric surface is typically 0.1 to 1.5 ft lower than the A- and B-zone water levels. The C-zone hydraulic gradient is to 0.004 ft/ft toward the east to southeast. D-zone The D-zone underlies the C-zone and consists of interbedded sand, silt, and clay encountered at depths exceeding 80 ft bgs. Limited data indicates that the hydraulic gradient is 0.001 to 0.004 ft/ft with an eastward flow direction. Depth-to-water at the site varies seasonally and ranges from just below ground surface to three ft bgs in the wet season to five to eight ft bgs in the dry season. The hydraulic gradient for A- zone, B-zone, C-zone, and D-zone range from 0.001 to 0.005 ft/ft and generally flows toward the east to southeast. SULFATE INJECTION SYSTEM DESCRIPTION The site had an injection system that was used to pilot test nitrate/sulfate injection. It consisted of three 275-gallon polyethylene tanks with stands, three ball valves, and a system control panel. The three 275-gallon polyethylene tanks (poly tanks) had an open top with removable lids, and conical bottoms. They were placed on stands to allow all liquid to drain through the one-inch opening located on the bottom of the tanks. A ball valve was placed directly below each tank for emergency shut-off. Flow from each tank was controlled at the control panel by ball valves which regulated flow through the 3/8 inch tubing. The system control panel took readings from three pneumatic pumps, three pressure gauges, three pressure regulators, and three rotometers. Pressurized air was received from an on-site compressed air line through a 3/8 inch air hose. The air hose had a quick disconnect at the system control panel and at the connection to the compressed air line. A valve was placed at the connection to the system control panel to initially regulate the air flow prior to the pressure regulators. The air hose was only connected to the system during injection events. Three pressure regulators and rotometers controlled each pump. The pressure regulators were used to monitor and adjust air pressure to each pump. The rotometer measured flow and allowed the system to regulate the nitrate/sulfate solution flow rate to each well. PROPOSED SCOPE OF WORK The objective of this work plan is to outline the work required to conduct an expanded pilot study of the sulfate injection program at the site. The data collected during the previous pilot study 40T Work Plan for Amended Bioremediation Pilot Study.doc 5