Laserfiche WebLink
outside of the casing. The use of tunnel liners will be <br />allowed only where the installation method and soil <br />conditions ensure that voids will not be formed around the <br />outside of the liner during installation. <br />5) Auger size and spacing - The leading auger section used in <br />conjunction with a cutting head must be full -sized having an <br />outside diameter not less than the inside diameter of the casing <br />less the amount needed to provide the minimum working clearance <br />necessary. In no case shall the auger diameter be less than 1/2 <br />inch smaller than the inside casing diameter unless some other <br />positive means of restricting the movement of the cutting head as <br />previously required is assured. Less than full -sized augers that are <br />large enough to remove spoil satisfactorily will be allowed when <br />the auger is not used in conjunction with a cutting head and is to <br />remain within the casing at all times, except as follows: <br />Minimum Length <br />in Feet of Full <br />Sized Auger from <br />Crossing Conditions Leading End of <br />Casing <br />Rock 0 <br />Hard -pan, clay, hard sand- (dry) 0* <br />clay <br />(wet) 20 <br />Stable cohesive soils (dry) 0 <br />(wet) 20 <br />Loose unstable soils (dry) 20 <br />(wet) 40 <br />Crossings requiring dewatering are to be considered as wet in the <br />above table. <br />09/03 16200 -13 03- 1438.A -R <br />