In his ruling, Haden said, "The AOC requirement and definition undeniably allow the use of some discretion in determining whether a permit meets the standard.
"The agency must make a case-by-case determination of whether the requirement is satisfied," Haden wrote. "This does not, however, give the agency carte blanche in making the determination."
Haden noted that Arch Coal's permit application showed that the Spruce mine would raise the valley floor of Pigeonroost Hollow by as much as 300 feet, and lower the elevation of mountains by as much as 200 feet.
"Current plans for regrading will leave five level or gently rolling areas, in stark contrast to the current topography," Haden wrote. "The post-mining elevation showed one flat or approximately level area, 6,000 feet in length, that had projected final elevations of less than 50 feet."
Haden also cited the testimony of John Morgan, a mining engineer working for environmental groups, that the final permit approved by DEP does not contain cross-section diagrams that would explain what the reclaimed mine site would look like.
"This lack of information prevents a determination of whether the proposed post-mining configuration will meet AOC," Haden wrote.
Haden recited testimony from DEP officials about the agency's old 50-foot rule. Under the rule, any change in elevation of more than 50 feet would mean a mine did not qualify as meeting the AOC rule.
DEP permit supervisor Larry Alt and assistant mining chief Lewis Halstead testified that the agency no longer uses the 50-foot rule, and doesn't consider elevation when determining if a mine meets AOC.
The larger the change in elevations that mines are allowed to make and still meet AOC, the more leftover rock and earth they will dump in valley fills. If the 50-foot rule were still used, either companies would have to get AOC variances - and propose post-mining development - or they would have to rebuild more of the mountains and bury less of the streams.
In his ruling, Haden said that DEP had not shown in court that the 50-foot rule had been legally repealed.
"The evidence demonstrates a serious question as to whether DEP is failing to apply a 50-foot rule that remains applicable," Haden wrote. "Such actions may demonstrate arbitrary and capricious behavior of DEP in violating or ignoring what may be a mandatory, nondiscretionary duty.
"Moreover, the evidence demonstrates Plaintiffs have raised substantial, serious questions going to the merits of whether Defendant Miano himself breached mandatory, nondiscretionary duties in his application of the AOC requirement," the judge wrote.