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of an old 12-inch diameter clay pipeline approximately 100 years <br />~ old. The line is in need of repair: it contains several <br />leaks in excess of 20 gallons/minute. Flow in the pipeline is <br />presently disrupted a short distance north of the Dorchester #1 <br />permit area. Because of the current condition of the pipe, any <br />significant subsidence could result in increased leakage and <br />under worse case assumptions, could potentially disrupt the flow <br />when the line is in use. However, a clear delineation of the <br />probable and actual impacts to the line as a result of <br />Dorchester's operations will be complicated by the current poor <br />condition of the water line. Dorchester's subsidence monitoring <br />and mitigation plans for the water line are given in Section 3.5. <br />2.7 ologjc Imp~ict on Subsidence <br />• This section deals with the potential impact of geologic <br />conditions on mine subsidence, including vertical and horizontal <br />ground strains at the surface. In the process of assessing this <br />impact, the following information provided by Dorchester Coal has <br />been reviewed: <br />• A geologic map of the Rockvale Quadrangle (Scott and <br />Taylor, 1974). <br />• A photogeologic map prepared by Dorchester Coal Company <br />(see Exhibit 1 of the Permit Submission (3/83)). <br />• Geology description of the Dorchester No. 1 Nine, <br />prepared by Wallace S. Platt s Associates (See Section <br />2.04.6 of the permit application). <br />• <br />22 <br />