40 



WEST REF was sampled at six randomly selected stations (STA5 falling outside the 300 m 

 sampling radius). NE REF was sampled at five randomly selected stations (STA1 falling 

 outside the 300 m sampling radius; Table 2-8). 



The random sampling protocol continued for the 1997 and 1998 field efforts with 

 NLON REF (41°16.666' N, 72° 01.971 ' W) and WEST REF (41° 16.206' N, 72° 

 05.971 ' W) each being sampled at four randomly selected stations. NE REF (41° 16.686' 

 N, 72° 03.371 'W) was sampled at five randomly selected stations. However, the center 

 coordinates and target station locations were reported in the horizontal control of NAD 83 

 (Figure 2-8; Table 2-8). 



2.3 Dissolved Oxygen Sampling 



All dissolved oxygen (DO) sampling activities were conducted 8 and 9 August 1992 

 and included CTD casts and Niskin bottle water sampling. Profiles were completed at one 

 station over the D/S mound (200 SW) and one station at each of the three reference areas 

 (Figure 2-9). In addition, surface and near-bottom water samples were collected at each 

 DO Station and subjected to Winkler titration to verify the CTD values. 



A Sea-Bird Electronics, Inc., Model SBE 19-01 CTD equipped with a centrifugal 

 pump and a SBE 13 Dissolved Oxygen Sensor was used to collect water column and near 

 bottom water quality data (temp, salinity, pressure, density, dissolved oxygen 

 concentrations). The CTD was allowed to equilibrate in ambient surface water for two 

 minutes before performing a cast. The descent rate was controlled to yield sufficient data 

 for each 1 meter horizon within the water column. As the CTD probe approached the 

 bottom, the unit was allowed to rest approximately 1 meter above the seafloor for a period 

 of one or more minutes before beginning the ascent. Upon retrieval from the water, data 

 was downloaded to a Toshiba® 3200T personal computer for analysis. 



Water samples were taken simultaneously with the CTD DO profile. A pair of 5- 

 liter Niskin bottles were tripped one meter below the air-water interface and one meter 

 above the sediment- water interface. A 300 ml subsample was taken from each Niskin 

 bottle, preserved, and titrated within twelve hours using the modified Winkler titration 

 (Strickland and Parsons 1972; Parsons et al. 1984). During routine quality assurance 

 review of the data, it was determined that the dissolved oxygen sensor on the CTD was 

 experiencing a malfunction that resulted in erroneous readings. Therefore, only the 

 Winkler titration DO determinations are presented in this report. 



The measurements obtained over two days during the August 1992 survey provide a 

 very limited, "snapshot" view of dissolved oxygen conditions within the disposal site and 



Monitoring Cruise at the New London Disposal Site, 1992 - 1998 



