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groundwater impacts as ated tti~th any of the small solution m~ng facilities active in New York in the late nineteenth and ~ tK•entieth centuries. TULLY VALLEY - A UNIQUE CASE HISTORY In caverns created by the method illustrated in Figure 2, solutioning occurs preferentially at the top of the cavern and insolubles blanket the floor, reducing the surface area of salt available for solutioning (Pullen, 1973). At many of the earliest wells in Tully Valle}•, as solutiontng proceeded awa}~ from the wellbore at the top of the cavern, the unsupported roof span would widen and eventually collapse. Wells would have to be shut down znd repaired because of tubing damage caused by this cavtng. Repeated caving and costly ~vorkovers would ultimately lead to well abandonment (Trump, 1936). Because of the blanketing effect, salt at the cavern bottom would be u~azted. Figure 3 shows the t}~pical configuration of early well completions in Tully Valley. Minimal or no cement .vas used, and tubing was suspended from the surface through a few hundred feet of open hole at the bottom of the wellbore. By 1893, Solvay Process Compan}• had drilled over 50 wells in Tull} Valley. T}•pical well spacing vas 150 to 300 feet. The associated caverns coalesced very earl}• in the field's history to form large multi-well galleries. Trump (1936) theorized that another means b}• which wells and caverns connected was by solutioning of salt mixed µith the overlying shale. Originally, the source of fresh «'ater for solutioning in Tully Valley was a series of glacial lakes located south of and upslope from the brine field. Because the lakes w•e;e at a higher elevation than the wells, a hydrostatic head existed that was Initially sufficient to force brine to the surface without pumping. This gravity-fed pipeline system, with fresh water flowing do~tinhill from the lakes to the well field, and brine flowing downhill 20 miles from the well field to the soda ash plant, was the first of many innovative techniques associated with solution mining in Tully Valley. Historical company engineering reports indicate that by 1900 it was becoming inereasinaly difficult to force brine to the surface using onl}• the pressure differentia! between the lakes and the brine field, and air lift vvas initiated. Trump (1936) attributed the problem to the hypothesized uncontrolled solution channels through the overlying shales previously described. The historical company reports, however, impute the difficulty to escape of fluids from the interconnected cavern rystem into the surrounding rocks and sediments. These reports cite a 1926 study which showed that 40 to 60% of the injected u~ater waz lost to "underground leakage" (Larkin, 1950). The cavern development methods discussed below were implemented «~ith the apparent objecti~ e of manmtzmg well life and salt recovery, while minimizing the costs azsoctated u~th workovers, air Ilfting, and the need for ever-increasing volumes of fresh water to maintain the desired output. Sore of these innovations riere successful in the short-term and, with respect to roof-padding, evolved into accepted standard industry practice. Unfortunately, long-term application of these techniques in Tully Valley resulted in widespread subsidence, sinkholes, and groundwater impacts. Cavern Development Innovations Rnojpadding.--Roof padding, the first modem technology implemented b}' the solution mining industry to control cavern shape, prevent waste of sal; at the cavern bottom, and mmimtze cavine during tie active life of the well, was invented in Tulle Valley by Edward \ Trump. This method invokes 6 ..'~'~J ~