This standard of review also resolves Dabbs's argument that the district court improperly based its conclusion on a secondary source, as we do not rely on that source in our de novo review. See Ball v. City of Dodge City, Kan., 67 F.3d 897, 899 (10th Cir. 1995) (explaining that, given our discretion to affirm on any ground supported by record, "we need not agree with all of the district court's reasoning").

"We review summary judgment determinations de novo, applying the same standard used by the district court under Fed.R.Civ.P. 56(c)." Ball v. City of Dodge City, 67 F.3d 897, 899 (10th Cir. 1995). Generally, the FLSA requires employers to pay employees a minimum wage for a forty-hour work week, as well as overtime for hours worked over forty per week. See 28 U.S.C. § 206, 207.

Finally, the city cites a number of Federal cases, arguing that in these cases "[S]tate collective bargaining obligations played no role and presented no hurdles" to the public employer's decision to adopt a § 207(k) work period. See Franklin v. Kettering, 246 F.3d 531, 535-536 (6th Cir. 2001); Lamon v. Shawnee, 972 F.2d 1145, 1151-1154 (10th Cir. 1992), cert. denied, 507 U.S. 972 (1993); Ball v. Dodge City, 842 F. Supp. 473, 474-475 (D. Kan. 1994), aff'd, 67 F.3d 897 (10th Cir. 1995). A Federal statute may preempt State law when it explicitly or by implication defines such an intent, or when a State statute actually conflicts with Federal law or stands as an obstacle to the accomplishment of Federal objectives.