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3.0 Coordination of Monitorin <br />As discussed above, the overall design for LFG control involves a primary area -wide LFG control <br />system monitored by the City, and secondary LFG sub -slab venting systems at each building <br />monitored by the owner of each development block. Those systems are intended to prevent a <br />complete exposure pathway involving the migration of LFG (i.e., methane) from the dump to the <br />interior of the new buildings. The following events would need to occur for there to be a complete <br />LFG exposure pathway: <br />• Methane (the primary constituent of concern for LFG) is generated in the dump <br />The City's area -wide LFG collection system at the dump fails to intercept the methane <br />• High concentrations of methane migrate past the perimeter monitoring network towards the <br />future building areas <br />High concentrations of methane are detected in the proposed sub -slab building venting <br />system by the development block owners <br />The sub -slab venting system fails to intercept the methane <br />• The methane enters the future building interior <br />• The building's indoor air exchange system fails to reduce/remove the methane in the <br />building and so elevated concentrations of methane mixes with oxygen in the indoor air and <br />create a potential explosion risk <br />The City and the development block owners will conduct monitoring of the LFG systems, and <br />potentially conduct contingent actions, to verify that the above complete LFG exposure pathway does <br />not exist. As shown on Figures 2 and 3, there will need to be coordination between the City and <br />development block owners if the City's monitoring at or near the dump identifies concerns with LFG <br />migrating beyond the City's primary area -wide LFG collection system. There are two key schedule <br />considerations regarding the approach for responding to elevated LFG readings in the monitoring <br />networks: <br />1. The City's monitoring of the area -wide system will provide the initial indication if LFG is <br />migrating along the pathway. The initial presence of elevated LFG at the City's monitoring <br />PAMpls\23 MM62\2362489\WorkFiles\Eastern RAP 2008\LFG CAP\Revised March 2009 CAP\LFG Contingency Action Plan z <br />Revised March 2009.doc <br />