wave theory (Ippen 1966, p 29). In the above, the parameter fw is defined as the bottom 

 friction coefficient (Jonsson 1966) and C] is the Chezy coefficient . The parameter r is 

 the hydraulic bed roughness and taken to be 0. 197 ft (0.06 m), (Van De Graff and Van 

 Overeem 1979). It should be noted that the bed roughness used in these calculations are 

 due to grain size (i.e., small horizontal scale) and bed-forms such as ripples, not bottom 

 formations such as rocky outcrops which, as will be described later, exist at the PDS (these 

 formations would indicate that the bottom roughness values increase significantly in rocky 

 areas, but in general it appears that these formations are in regions of the PDS where few 

 sediment deposits exist and therefore are not accounted for here). The terms H, k, ,a and 

 T represent wave height (ft), wave number (ft"'), angular frequency (sec"') and period 

 (sec) respectively. The terms d and g represent water depth (ft) and acceleration of gravity 

 (ft sec"^) respectively. This method assumes that current and orbital velocities are oriented 

 in the same direction which is, in general, a conservative assumption which may result in 

 shear stresses being slightly higher. 



1.2 Non-Cohesive Sediment Transport Model Component 



The equations reported by Ackers and White (1973) were selected as the basis for 

 the non-cohesive sediment transport modeling component. These relationships predict 

 sediment transport primarily as a function of sediment grain size, depth, and depth 

 averaged velocity (here the depth averaged velocity is assumed to be Vwc). The equations 

 are applicable to uniformly graded noncohesive sediment with a grain diameter in the range 

 of 0.04 mm to 4.0 mm (White 1972). 



The Ackers-White transport equations relate sediment transport to three 

 dimensionless quantities. The first, a nondimensional grain size Dgr , is defined as a 

 function of the ratio of the immersed particle weight to the viscous forces acting on the 

 grain. The value is defmed as: 



D„=D 



8{s-\) 



(7) 



where: 



D = sediment diameter (i.e., Dso), ft 

 g = acceleration of gravity, ft/sec^ 

 s = sediment specific gravity 

 V = fluid kinematic viscosity, ft^/sec 



A Predictive Model for Sediment Transport at the Portland Disposal Site, Maine 



