One more thing you might want to read what the USA OSHA (Occupational Safety & Health Act) says about ammonia. While it is not common for things being transported over the road via tractor (trailer or tanker) to overturn they do happen- mostly around refineries & chemical plant - lived in Houston, Pasadena and been thru Beaumont, TX many times ( recall the free way shutdown when it happened) Don't think I'd want any thing like this to tip over in my neighborhood who would - raise their hand.
www dot osha dot gov/SLTC/etools/ammonia_refrigeration/emergency/index (dot.html replace dot with / and delete spaces