SITE INFORMATION AND CORRESPONDENCE

Home Browse Search

,x Besides the low water float switch, the Baker tank was also equipped with a high level float switch which was set approximately at the mid point of the tank capacity. The high level float switch was configured to electrically shut off the excavation pump when the water level reached the half way point of the tank or when electrical power to the float switch itself failed. This fail-safe feature was incorporated to prevent the Baker tank from overflowing in.the unlikely event that power to the high water level cut-off switch was interuppted and power to the excavation pump remained intact. On Tuesday, February 26, 2003 at 9:45 AM, 'Mr. George Converse, a geologist for Western Geo-Engineers, discovered that water was overtopping the Baker tank and flowing into the gutter on the northern margin of Roselawn Avenue. Mr. Converse observed that the waste water was flowing east in the gutter and had entered the storm drain system through the grating at the northwest corner of the intersection of Roselawn and Buena Vista Avenues. Mr. Converse shut off the excavation pump that had been discharging water to the Baker tank at a rate of 4 gallons per minute. Calculation of the Volume of the Unauthorized Release WEGE was able to calculate the volume of waste water that was released to the storm drain system with the aid of the water totalizing meters that had been incorporated into the discharge system. The system included a meter that recorded the total volume of water in gallons that were pumped from the excavation into the Baker tank and a separate calibrated meter that recorded the total volume of water in gallons that were pumped from the Baker tank through the carbon cannisters and into the sanitary sewer. A WEGE technician had recorded the readings from both meters at 3:00 PM on Friday, February 21, 2003 when the water level in the Baker tank was known to be at 1.4 feet from the base of the tank. Mr. Converse also recorded both meter readings at 9:45 AM on Tuesday, February 25, 2003 when he discovered the overflow from the tank and shut off the excavation pump. To calculate the amount of the release, WEGE subtracted the number of gallons of water that were pumped to the sewer system between the two meter readings on Febraury 21 and February 25 from the total amount of water that was pumped from the excavation to the Baker tank during the same time period. ' From this difference WEGE then subtracted the unused capacity in the Baker tank of 20,181 gallons that existed on February 21, 2003 at 3:00 PM to arrive at 1,951 gallons of waste water that overtopped the Baker tank. See enclosed Table 4 for the recorded water meter readings and calculation of estimated spillagefrom the Baker tank. Calculation of the Maximum Volume of Gasoline in the Unauthorized Release The concentration of gasoline in the groundwater-that was being pumped;from the open excavation to the Baker Tank was not tested on a regular basis and most likely varied considerably with the elevation of the groundwater in the excavation. From previous ground water samples collected at the monitor wells at the site and one sample of the excavation water itself, WEGE estimates that the maximum concentrations of TPH-G in groundwater leaving the excavation are 9,000 to 10,000 ug/1 or 9-10 ppm. At this 2