I have a lot of practical experience in this very matter. I had a crew of mainly Indians, Pakistani's, one Egyptian, Bangladeshis, Thai, and Filipino's. I had one Indian who could barely speak English and NO professional translators. Halliburton's management were ****ing morons to put it mildly. My job was to lead this crew of "professional" drivers in a combat zone and deliver fuel from the main fuel distribution points to the local FOB bag farms. I was responsible for their safety and performance and general everyday living arrangements and pay. As even Ray Charles can see, and he's dead, that one translator at the least would be very important. I had to get by without one.
Here are some tips to deal with that situation. The very first thing I would do if I were you is go inform your management you need a competent translator to communicate with this individual. If they dont and that individual gets you or others or themselves hurt on the job they will have OHSA breathing down their necks and will take a piece of their hides if they are lucky. It IS an OHSHA requirement that ALL workers be able to communicate, and receive communication of job hazards and safety information. So make sure they are informed and make sure YOU document it. If there is an accident you will want that documented you communicated this fact to management. Now if they dont fire the person in question then get yourself a white board and markers. Your gona be doing a lot of charades and hands on work. Your going to be saying things over and over and over and over and over and over again. Get used to it. Next start learning Somali and start teaching her English. Its going to be pidgin but it will help get you by. Know that your interactions are going to be time intensive. By the way whenever I had Somali's on my crews, those sorry bastards were the some of the most stubborn people I have ever run across. I absolutely hated working with them. It got to the point I would not let them on my crews. Hopefully your Somali is the exception to the rule. By the way if they hired her for affirmative action, that dont trump safety in the eyes of OSHA. I dont know what you do and how much effort you want to put into this, but your company if they are gona do this employee right ought to be helping her learn English as well as you from a safety standpoint for yourself and your crews.