CORRESPONDENCE_1999-2002 - Laserfiche WebLink

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'pPqu!!y,,.co COUN7Y OF SAN JOAQUIN THOMAS R.FLINN DEPUTY DIRECTOR y: .� DEPARTMENT LIC WORKS P.O.BOX 1810- 1810 EAST HAZELTON AVENUE MANUEL LOPEZ •' STOCKTON,CALIFORNIA 95201-1810 DEPUTY DIRECTOR 209/468-3000 STEVEN WINKLER C�C/F FAX:209/468-2999 DEPUTY DIRECTOR 0 HENRY M. HIRATA DIRECTOR January 11, 2000 MEMORANDUM TO: Robert McClellon, Lead Senior R.E.H.S. Public Health Services Environmental Health Division FROM: Wes Johnson 5 Associate Civil Engineer SUBJECT: LANDFILL GAS CONTROL SYSTEM MODIFICATIONS HARVEY LANE SANITARY LANDFILL On September 19, 1999, the Solid Waste Division submitted a work plan describing proposed modifications to the landfill gas control system at the Harney Lane Sanitary Landfill. After submittal of the work plan, further investigation revealed that a different approach to the modifications would give the County the greatest chance for success in controlling the subsurface gas migration. The following is a revised work plan describing our new approach to gas system modifications. Due to the need to control migration in a timely manner, the work plan has already been implemented. CONDITIONS PREVIOUS TO MODIFICATIONS The landfill gas system used one blower to apply vacuum to the entire site. One eight-inch High Density Polyethylene (HDPE) pipe connects the blower to the six-inch header pipes that run along the east and west sides of the landfill. There is also one condensate knockout sump between the landfill and the flare station. One blower produces approximately 15 inches (water column) of vacuum as measured at the blower inlet. Pressure drops caused by pipe elbows and distance results in about 12 inches where the pipe splits. The split cuts the vacuum to each half of the landfill to approximately six inches each. The vacuum drops even further as you move north. The collection wells farthest north on the site, on average, produced vacuum of less than one inch. The northern area of the landfill contains the most recent and highest methane producing waste, so it is logical that all of the subsurface migration of landfill gas occurs around the north half of the site.