Mealey's (June 18, 2015, 3:07 PM EDT) -- DENTON, Texas — Two environmental groups on Dec. 4, 2014, moved in Texas court to intervene in the lawsuit brought against the City of Denton by an oil and gas trade association that contends that the city’s ban on hydraulic fracturing is unconstitutional (Texas Oil and Gas Association v. City of Denton, No. 14-08933-431, Texas Dist., 431st Jud. Dist., Denton Co.)....