Access to site. All well sites on the refuge are reached by dredged 

 canals. Canals are typically 21 m (70 ft) wide and 2.4 m (8 ft) deep. Canal 

 development is incremental. A first canal will be dredged off a main channel 

 or pass and a well will be drilled. After the well has been drilled, a new 

 canal will begin where the first left off and proceed to a new location 0.3 to 

 0.6 km (1,000 to 2,000 ft) away. A new well will be drilled, and the canal 

 will again be extended. 



Siltation from the Mississippi River is a major problem in the access 

 canals. Maintenance dredging is often required. Spoil from dredging is often 

 placed adjacent to the channel by bucket dredges. Occasionally a hydraulic 

 dredge is used and when it is convenient, the outfall is placed in some of the 

 deeper interdistributary ponds. The sediment deposited makes these ponds 

 shallower and allows them to develop the type of vegetation usually formed 

 before subsidence caused the ponds to become too deep to support plant growth. 

 Older dredge sites sometimes had very high spoil mounds of 5 to 6 m (16 to 

 20 ft). Spoil is now kept to lower elevations so that spoil banks may occa- 

 sionally be topped by high spring flood water. 



The routes taken in the dredging are usually the most direct, and they 

 may cross ponds and lakes. On occasion, complete canal systems may be intercon- 

 nected by channels between one series of canals and another. The effects on 

 circulation in the canals is unknown. In both fields, efforts have been taken 

 to reduce the siltation problem. This included construction of bypass channels 

 and rerouting of canals into the inner marsh areas so the entrance canals made 

 sharp angles with pass channels. 



Site preparation and operation. Wellsites are prepared for floating 

 drilling rigs. A typical location site is 43 by 113 m (140 by 370 ft) and 

 2.5 m (8 ft) deep. Spoil is placed around the drill site to partition off the 

 rest of the marsh. A typical location site may require removal of 11,600 m3 

 (15,200 yd3) of sediment. 



Density of canals and wellsites on the Delta Refuge is impressive. One 

 map showing an area of marsh 2.6 by 3.2 km (1-6 by 2 mi ) had over 110 wellsites 

 on it, plus all the canals leading to the sites. The development is so exten- 

 sive that Gusey and Maturgo (1972) reported that nearly 3,645 ha (9,000 acres) 

 of the refuge's 19,764 ha (48,800 acres) have been substantially altered by 

 extensive crisscrossing of access canals and wellsites. 



Drilling operations are restricted to the time of year when migratory 

 waterfowl are not present. All equipment is contained on barges, and drilling 

 operations proceed in a manner similar to that for sites off the refuge. 



Placement and operation of production facilities. The Delta Duck opera- 

 tion has three separate tank batteries. One of these is placed on barges and 



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