1 At normal current speeds of 10 cm/sec, it requires about 30 



2 minutes to dilute the drilling mud that much, and the distance from the 



3 platform, given a 10 cm/sec current speed, which would be very normal 



4 for Georges Bank, that is accomplished within less that 200 meters of 



5 the platform. 



6 So, basically what these calculations imply is that dilution of 



7 the drilling mud is sufficiently rapid that even having to dilute it 



8 down to 10 ppm or less to protect all the animals out there, based on 



9 laboratory studies, would be accomplished within half an hour and within 



10 200 meters of the platform. 



11 Based on data like this, the National Academy Panel came to the 



12 conclusion that it is very unlikely that we would ever see any impacts 



13 of drilling discharges on planktonic and pelagic animals and plants, but 



14 basically the dilution is rapid and the area of potential impact is so 



15 small, that nothing would happen measurable in the water column. 



16 However, 90 percent of the drilling mud and virtually all of the 



17 cuttings upon discharge rapidly settled to the bottom. Obviously where 



18 they accumulated in significant quantities, they are more persistent and 



19 they could cause impacts where drilling fluids are accumulated. 



20 Going on to, you might say, field-validate the last graph, several 



21 years ago I took the data from several field studies in five different 



22 locations, Louisiana, New Jersey, Alaska, California, and another Alaska 



23 one, and plotted the transport time, that is the distance versus the 



24 current speed, versus the concentration of total suspended solids in the 



25 water column during actual discharges. 



26 You can see there is a logarithmic decrease in total suspended 



27 solids, which is a good measure of drilling mud concentration. These 



28 values over here are the background concentrations, and you really need 



29 to normalize against what the background suspended-solids concentration 



30 is. 



31 So, in Norton Sound over here, the study was done during a period 



32 when there were ^^ery high background concentrations. 



33 So, the decay period, you might say, for Norton Sound drilling 



34 fluids is not as steep as that for these other areas here where there 



91 



