sediment compartment and variable SED(K,I)

Hello, I have been looking through and trying to understand the source code for the SEDIMENT and other associated routines. Near the begining of the main W2 program, the SEDCI variable, which is the initial sediment concentration input by the user, is assigned to the SED variable for every K and I in the waterbody. The SED variable is then used in the KINETIC_RATES routine for calculation of the first order decay of OM and is updated in the SEDIMENT routine for every K and I. The amount of OM decay is used in the DISSOLVED_OXYGEN routine as a sink for DO. From inspection of the code, it appears that the units for the SED variable should be (grams)/(cubic meters). However, the W2 user's manual lists units for the SEDCI input variable as (grams)/(square meters). Which are the correct units? The units listed in the manual would make sense if the sediment layer was assumed to be 1 meter thick. Or am I not understanding the code? thanks for any response, Alex[addsig]