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October 2000 -44- 003-2191 <br />• 500 feet to the west. In the unlikely even[ of a leachate release from the facility, the <br />potential risk of environmental impact atoff--site locations appeazs to be insignificant. <br />3.2.5(C)(2) The Alternative Design of the Barrier Layer is to GCL <br />As noted above, the barrier layer is to be 3 feet of compacted on site clay. This clay has <br />been shown to have a permeability less than the required 1 x 10'' cm/sec, A GCL will <br />be the alternate design. The natural lithology (shale) material beneath the site provides <br />additional protectionto underlying groundwater. Shale isdefined as afine-grained rock <br />formation formed by the hardening of clay. The thickness of the natwal barrier layer <br />was defined by drilling exploratory holes within the depository area and by correlating <br />the same with the geophysical logs in the surrounding azea. The minimum thickness <br />measured was 60 feet. <br />Well M3, which is at the south end of the planned pit, was cored with a full diameter <br />• core barrel to obtain cores of the barrier layer rocks. These cores were inventoried on <br />site by a registered professional engineer and were analyzed for consistency and <br />thereafter correlated to the geophysical gamma and neutron logs on the holes. <br />3.2.5(D) Leachate Collection and Leachate Removal System <br />The leachate collection system will consist of a series of temporary and then permanent <br />sumps and a series of lateral drains located directly beneath the depository and on top of <br />the 3 foot liner (see Drawing 3). The estimated leachate produced by the depository is <br />only 4.5 gallons per minute. The diameter of the drains will be 4.0 inches which is <br />considered to be more than adequate for the low flows anticipated. The slope of the <br />drains will follow the contour of the bottom of the facility at approximately 5%. The <br />required spacing of the drains is calculated using Hooghout's formula as follows: <br />• <br />wnawirsieis~dd,.r~~nooo m~ Sedalia Recycling Center and Depository <br />