If marijuana use reduction is your primary concern with this population, I recommend the evidence-based SPORT Prevention Plus Wellness program. Its the only single-session evidence-based SUD prevention program, and its cheap and sustainable. 1 time manual purchase includes online training and all materials are reproducible.
I do pre/post testing with my participants and am still stunned by the outcomes.
Cost-Benefit Analysis by Washington State Institute for Public Policy: For every $1 invested, SPORT returns $223 to society.
http://www.wsipp.wa.gov/BenefitCost/Program/382
Evidence-based Practice Registry