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Todd Del Frate -2- <br /> INCREASE IN CORRECTIVE ACTION AND OTHER ISSUES, F ILL LANDFILL <br /> The second development we discussed is the indication that some leachate can reach the <br /> secondary containment sump below Module 1 primary leachate sump. <br /> We have been removing liquid from the secondary sump monthly since April 2009 when it was <br /> discovered that landfill condensate had been accidently pumped there. After the initial removal, <br /> the volume collected gradually decreased to between three and ten gallons, for an average <br /> collection rate of between 0.3 and 0.6 gallons per day. Prior to removal, the water level within <br /> the secondary sump is approximately 7 inches. After removal, the water level is less than <br /> 3 inches. <br /> The primary sump above the secondary containment is provided with an automatic pump which <br /> normally maintains the leachate level of between 17" and 36". However, in Mid-April, after a <br /> particularly wet March, intermittent failure of fuses prevented the normal operation of the <br /> primary sump pump. It was determined that a PG&E transformer was malfunctioning, which <br /> was immediately replaced. The leachate level within the primary sump rose to approximately <br /> 100 inches during that time. Surprisingly, a total 240 gallons was removed from the secondary <br /> sump that day. <br /> Since replacing the transformer and restoring the primary sump to normal operation, the <br /> removal of liquid from the secondary sump has returned to the normal rate. <br /> Based on this experience, we are forced to conclude that there is a small hydraulic connection <br /> between the primary and secondary sump. Unfortunately, our observations do not allow us to <br /> determine the location of this connection. The bottom of the primary sump is approximately 33 <br /> feet below the surface, under refuse and drain rock. <br /> We therefore propose to automate and make permanent the pump now installed in the <br /> secondary sump. Based on the operation of this pump to date, we will be able to maintain the <br /> water level in the secondary sump below 12 inches. Anticipated withdrawal rate is <br /> approximately 0.5 gallons per day, which would be plumbed directly into the primary sump. <br /> If you have any questions, please contact me at (209) 468-8504. <br /> Sincerely, <br /> 'e <br /> W. MICHAEL CARROLL, PE <br /> Senior Civil Engineer <br /> WMC:sc <br /> N:\1 Foothill\Groundwater Mon itoring\TDelFrate02-1 ncrCorrAct.doc <br /> Attachment <br /> c: Robert McClellon, Environmental Health Department <br /> LA 31610 <br />