28 



Table 3-2 



Seasonal Wave Statistics for the Period from January 1993 through May 1996 

 as Observed by NOAA Buoy 44007 





Mean 



Wave 



Height 



(m) 



Maximum 



Wave 



Height 



(m) 



Mean 

 Wave 

 Period 



(sec) 



Percent of Wave Height Observations 





>lm 



>3m 



>5m 



Winter 



1.22 



6.00 



8.16 



52.1 



4.4 



0.3 



Spring 



1.06 



7.00 



8.27 



45.0 



2.5 



0.3 



Summer 



0.68 



2.70 



7.69 



16.6 



0.0 



0.0 



Fall 



0.97 



7.30 



8.25 



38.5 



2.0 



0.2 



3.2.4 Duration of Storm Waves 



As illustrated in the time series of significant wave heights for the 3.4 years of data 

 from NOAA buoy 44007 (Figures 3-3a through 3-3d), the duration of large waves during the 

 passage of major storms is relatively brief, often persisting for only a fraction of a day. A 

 quantitative analysis of the duration of waves within specific height ranges (Table 3-3) 

 reveals that waves greater than 3 m had average durations of 6 to 8 firs; waves in this height 

 range were observed on 72 (31 + 15+26) occasions for a total of 562 hours (approximately 

 165 hrs or 7 days per year). In contrast, wave heights greater than 5 m were observed only 

 22 times, with average durations of only 1 to 3 hrs, for a total of 59 hrs. Therefore, 

 although large waves are not uncommon in the vicinity of PDS, they normally do not persist 

 for long periods of time. 



3.2.5 Meteorological Conditions during Spring of 1996 



Meteorological and wave conditions during spring of 1996 were similar to spring 

 conditions during the three prior years (see Section 3.2.3). As indicated in the time series of 

 observations from NOAA buoy 44007 during the period from March through May 1996 

 (Figure 3-4), there was a gap in the wind record from March 10 to April 1, but the available 

 wind data illustrate typical, synoptic fluctuations in wind speed on time scales of hours to a 

 few days, the latter being associated with the passage of large-scale meteorological systems. 

 Wind speeds approached 34 mph (15 m/sec) on a few occasions, but these maximum winds 

 persisted for only a few hours during the individual storms. Three-hour low pass filtered 

 wind vectors during spring of 1996 (second tier from the top in Figure 3-4) illustrate the high 

 Oceanographic Measurements at the Portland Disposal Site during Spring of 1996 



