Save Our Sperrins chair Cormac McAleer said he brought the case to court "because there has been such a lack of transparency on the earlier planning applications and how they were handled".
He told the Mail he had questioned "how the initial planning application (K/2013/0072) could have been validly approved with an explosives store located in a site known to contravene Separation Regulations", but that he was refused the information "on the grounds of 'national security'".
And he has hailed the news that a judge ruled he should be provided with that information by mid December.
In a statement, Save Our Sperrins welcomed the decision by Judge David Farrer QC at Belfast High Court in October 2016.
They said: "The case arose out of questions about the handling of Dalradian’s planning applications in 2013 and whether appropriate procedures were used by Strategic Planning Division.
"Cormac McAleer had sought information from the Health & Safety Executive NI and dissatisfaction with their responses led to a series of appeals and reviews that eventually resulted in the High Court appearance to challenge the stance of the Health & Safety Executive, the PSNI and the Information Commissioner that release of the information should be refused on the grounds that ‘disclosure of the information would adversely affect national security and public safety’.
"The judgement found that the argument of the PSNI that granting the appeal would risk ‘national security or public safety’ did not stand up as Mr McAleer’s team proved convincingly that the contested information was already in the public domain.
"Save Our Sperrins (SOS) welcomes the ruling as a victory for transparency and as a signal that the public sector should not consider themselves immune from being accountable to the people."
Cormac added: "I am hoping the information soon to be released will help cast some light on these matters."
In response the Health & Safety Executive said: "The Health and Safety Executive for Northern Ireland (HSENI) is aware of the decision in the case of Cormac McAleer –v- The Information Commissioner & The PSNI. HSENI is considering the judgement."
A spokesperson for the PSNI added: "PSNI accepts and has agreed with the decision of the Information Tribunal. During the course of the Tribunal proceedings it became clear information already in the public domain within planning documentation (paras 23 – 28 of the decision) would not endanger national security. PSNI agrees with the Tribunal decision that the Health and Safety Executive NI should now release this information to the applicant."PSNI provided evidence to the Tribunal and has welcomed the Tribunal’s decision that certain detail within the requested information should not be released. The Tribunal found to do so would endanger national security or public safety and considers that the balance of the public interest requires this information be withheld. PSNI agrees with those steps the Tribunal has ordered Health and Safety Executive now to take."